ORCID Profile
0000-0001-5296-6155
Current Organisations
Garvan Institute of Medical Research
,
Cellular Genomic Futures Institute, UNSW Sydney
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Publisher: Springer Science and Business Media LLC
Date: 07-1995
DOI: 10.1038/376181A0
Abstract: The recessive mouse mutations lpr and gld create deficiencies in an interacting pair of cell surface molecules, CD95 (Fas/APO-1) and Fas-ligand (FasL), respectively, resulting in autoantibody production resembling human systemic lupus erythematosus. The mechanisms of self-tolerance affected by deficiency in either molecule are not established, but CD95 deficiency both in B cells and in CD4+ T cells recognizing major histocompatibility complex (MHC) class II molecules is required for autoimmunity in lpr mice. Here we track the outcome of in vivo interactions between B cells and CD4+ T cells that recognize a transgene-encoded autoantigen, hen egg lysozyme (HEL), using cells from mice transgenic for immunoglobulin and T-cell receptor (TCR) genes. B cells that had not previously encountered HEL autoantigen (naive cells) were triggered into proliferation and antibody production upon interaction with antigen and HEL-specific CD4+ T cells. By contrast, B cells that had been chronically exposed to HEL during their development and carried desensitized surface immunoglobulin (sIg) antigen receptors (anergic cells) did not produce antibody but instead were eliminated in the presence of HEL-specific CD4+ T cells. CD95-deficient anergic B cells, however, were not eliminated by CD4+ T cells and were triggered to proliferate. These findings identify a novel regulatory step for eliminating autoreactive B cells that seems unique in its dependence on CD95.
Publisher: Wiley
Date: 04-06-2018
Abstract: Cancer cells seem to exploit mechanisms that evolve as part of physiological tolerance, which is a complementary and often beneficial form of defense. The study of physiological systems of tolerance can therefore provide insights into the development of a state of host tolerance of cancer, and how to break it. Analysis of these models has the potential to improve our understanding of existing immunological therapeutic targets, and help to identify future targets and rational therapeutic combinations. The treatment of cancer with immune checkpoint inhibitors aims to reverse the progression to tolerance of cancer, and achieve an immunogenic, rather than tolerogenic, homeostasis. Broadening the efficacy and durability of checkpoint inhibitors focuses on reversing tolerance and stimulating immunogenicity in the cancer, host, and environment. Two ex les of important physiological states of tolerance that may inform tolerance of cancer are microbial infection and placental reproduction. These states of tolerance result from bilateral shaping of host and non-self, akin to immunoediting in cancer, and offer reliable models to study the immune tolerance paradigm.
Publisher: Elsevier BV
Date: 05-1999
DOI: 10.1016/S0167-5699(98)01440-6
Abstract: B-cell development differs significantly from T-cell development in that negative selection of autoreactive B cells can occur in the same microenvironment in which productive immune responses begin. Here, Sarah Townsend and colleagues discuss how this 'growing up on the streets' might provide a mechanism that fills holes in the B-cell repertoire, much as major histocompatibility complex polymorphism fills holes in the T-cell repertoire.
Publisher: Cold Spring Harbor Laboratory
Date: 02-07-2021
DOI: 10.1101/2021.07.01.450650
Abstract: CD21 low age-associated or atypical memory B cells, enriched for autoantibodies and poised for plasma cell differentiation, accumulate in large numbers in chronic infections, autoimmune disease and immunodeficiency, posing the question of what checkpoints normally oppose their excessive accumulation. Here, we reveal a critical role for the calcium-NFAT-regulated transcription factors EGR2 and EGR3. In the absence of EGR2 and EGR3 within B cells, CD21 low and B1 B cells accumulate and circulate in young mice in numbers 10-20 times greater than normal, over-express a large set of EGR2 ChIP-seq target genes including known drivers of plasma cell differentiation and under-express drivers of follicular germinal centers. Most follicular B cells constitutively express Egr2 proportionally to surface IgM down-regulation by self-antigens, and EGR2/3 deficiency abolishes this characteristic anergy response. These results define a key transcriptional checkpoint repressing CD21 low B cell formation and inform how NFATC1 or EGR2 mutations promote B1 cell-derived chronic lymphocytic leukemias.
Publisher: Springer Science and Business Media LLC
Date: 06-2007
DOI: 10.1038/NATURE05875
Abstract: Accumulation of DNA damage leading to adult stem cell exhaustion has been proposed to be a principal mechanism of ageing. Here we address this question by taking advantage of the highly specific role of DNA ligase IV in the repair of DNA double-strand breaks by non-homologous end-joining, and by the discovery of a unique mouse strain with a hypomorphic Lig4(Y288C) mutation. The Lig4(Y288C) mouse, identified by means of a mutagenesis screening programme, is a mouse model for human LIG4 syndrome, showing immunodeficiency and growth retardation. Diminished DNA double-strand break repair in the Lig4(Y288C) strain causes a progressive loss of haematopoietic stem cells and bone marrow cellularity during ageing, and severely impairs stem cell function in tissue culture and transplantation. The sensitivity of haematopoietic stem cells to non-homologous end-joining deficiency is therefore a key determinant of their ability to maintain themselves against physiological stress over time and to withstand culture and transplantation.
Publisher: American Society of Hematology
Date: 18-08-2011
DOI: 10.1182/BLOOD-2011-04-346056
Abstract: Foxp3+ regulatory T cells play a pivotal role in maintaining self-tolerance and immune homeostasis. In the absence of regulatory T cells, generalized immune activation and multiorgan T cell–driven pathology occurs. Although the phenomenon of immunologic control by Foxp3+ regulatory T cells is well recognized, the comparative effect over different arms of the immune system has not been thoroughly investigated. Here, we generated a cohort of mice with a continuum of regulatory T-cell frequencies ranging from physiologic levels to complete deficiency. This titration of regulatory T-cell depletion was used to determine how different effector subsets are controlled. We found that in vivo Foxp3+ regulatory T-cell frequency had a proportionate relationship with generalized T-cell activation and Th1 magnitude, but it had a surprising disproportionate relationship with Th2 magnitude. The asymmetric regulation was associated with efficient suppression of Th2 cells through additional regulations on the apoptosis rate in Th2 cells and not Th1 cells and could be replicated by CTLA4-Ig or anti–IL-2 Ab. These results indicate that the Th2 arm of the immune system is under tighter control by regulatory T cells than the Th1 arm, suggesting that Th2-driven diseases may be more responsive to regulatory T-cell manipulation.
Publisher: American Society of Hematology
Date: 19-09-2013
DOI: 10.1182/BLOOD-2013-02-482331
Abstract: The development and survival of mature NKT cells are impaired in DOCK8-deficient mice. DOCK8 is required for antigen-induced NKT cell proliferation and cytokine production.
Publisher: Elsevier BV
Date: 12-2007
Publisher: Proceedings of the National Academy of Sciences
Date: 27-08-2020
Abstract: Conformational ersity of foreign antigens and cross-reactivity with self are implicated in the failure to generate effective antibody responses against many challenging pathogens, but few studies directly address how these two factors affect antibody formation. Here we address this question from biophysical, structural, and immunological perspectives using structurally related lysozyme proteins. The results show germinal centers have remarkable ability to select antibody producing cells along novel hypermutation trajectories, transmuting an antibody with no capacity to differentiate foreign from self into highly foreign-specific antibody derivatives, exploiting conformational flexibility in antigen and antibody. These findings address a central issue for developing vaccines against HIV and other chronic infections and represent a prime ex le of stepwise, evolutionary adaptation of protein–protein interfaces.
Publisher: Springer Science and Business Media LLC
Date: 03-05-2022
DOI: 10.1186/S13058-022-01525-Z
Abstract: The interferon response can influence the primary and metastatic activity of breast cancers and can interact with checkpoint immunotherapy to modulate its effects. Using N -ethyl- N -nitrosourea mutagenesis, we found a mouse with an activating mutation in oligoadenylate synthetase 2 ( Oas2 ), a sensor of viral double stranded RNA, that resulted in an interferon response and prevented lactation in otherwise healthy mice. To determine if sole activation of Oas2 could alter the course of mammary cancer, we combined the Oas2 mutation with the MMTV-PyMT oncogene model of breast cancer and examined disease progression and the effects of checkpoint immunotherapy using Kaplan–Meier survival analysis with immunohistochemistry and flow cytometry. Oas2 mutation prevented pregnancy from increasing metastases to lung. Checkpoint immunotherapy with antibodies against programmed death-ligand 1 was more effective when the Oas2 mutation was present. These data establish OAS2 as a therapeutic target for agents designed to reduce metastases and increase the effectiveness of checkpoint immunotherapy.
Publisher: Wiley
Date: 08-1991
Publisher: Springer Science and Business Media LLC
Date: 02-2008
DOI: 10.1038/NATURE06729
Publisher: AMPCo
Date: 12-1998
Publisher: Wiley
Date: 16-03-2005
DOI: 10.1111/J.0105-2896.2005.00253.X
Abstract: The cause of common organ-specific autoimmune diseases is poorly understood because of genetic and cellular complexity in humans and animals. Recent advances in the understanding of the mechanisms of the defects underlying autoimmune disease in autoimmune polyendocrinopathy syndrome type 1 and non-obese diabetic mice suggest that failures in central tolerance play a key role in predisposition towards organ-specific autoimmunity. The lessons from such rare monogenic autoimmune disorders and well-characterized polygenic traits demonstrate how subtle quantitative trait loci can result in large changes in the susceptibility to autoimmunity. These data allow us to propose a model relating efficiency of thymic deletion to T-cell tolerance and susceptibility to autoimmunity.
Publisher: The American Association of Immunologists
Date: 07-2010
Abstract: CD45 is the most abundant protein tyrosine phosphatase in the plasma membrane of T cells and serves a critical role in TCR signaling. Different CD45 isoforms are made by alternative mRNA splicing depending on the stage of T cell development and activation, yet their role remains unclear. Expression of CD45RA and RC isoforms is increased 20- to 200-fold on T cells from thunder mice with a loss-of-function mutation in the RNA-binding protein, heterogeneous nuclear ribonucleoprotein L-like (hnRNPLL), although total CD45 expression is unaltered. In this study, we test the hypothesis that this shift in CD45 isoform expression alters TCR signaling, thymic selection, and accumulation of peripheral T cells. There was no discernable effect of the change in CD45 isoform expression upon Lck phosphorylation or T cell positive and negative selection, whereas these indices were strongly affected by a decrease in the overall amount of CD45 in Ptprc mutant animals. The one exception to this conclusion was in thymocytes from Ptprcloc/loc animals with 4% of normal CD45 protein levels, where Lck505 phosphorylation was increased 25% in Hnrpll mutant cells, suggesting that high m.w. CD45 isoforms had lower Lck505 phosphatase activity in this context. In T cells with no CD45 protein, hnRNPLL mutation still diminished peripheral T cell accumulation, demonstrating that hnRNPLL regulates T cell longevity independently from its effects on CD45 splicing.
Publisher: Wiley
Date: 09-2008
DOI: 10.1111/J.1445-5994.2008.01719.X
Abstract: Several important physiological and maturational changes occur in sleep development during the paediatric age range, particularly during infancy and in early childhood. As the pathology of sleep apnoea is superimposed onto a developing and often plastic physiological system, children often show a different pathophysiology to their adult counterparts. These factors need to be incorporated into the evaluation of a child's sleep problems. Particular attention should be paid to the developmental stage of the child. Investigation, interpretation and subsequent management provide further unique challenges and during successive reviews predicted normal changes must also be taken into account. This review article discusses the important physiological and maturational changes that occur in sleep during childhood, some common paediatric sleep conditions and their presentation and the appropriate evaluation and management of these conditions. In the course of the discussion, we have stressed important differences between paediatric and adult sleep medicine.
Publisher: Public Library of Science (PLoS)
Date: 2007
Publisher: Proceedings of the National Academy of Sciences
Date: 28-07-2010
Abstract: Autoimmune polyendocrinopathy syndrome type 1 (APS1) results from homozygous Aire mutations that cripple thymic deletion of organ-specific T cells. The clinical course in man and mouse is characterized by high variability both in the latent period before onset of autoimmune disease and in the specific organs affected, but the reasons for this are unknown. Here we test the hypothesis that the latent period reflects the failsafe action of discrete postthymic mechanisms for imposing self-tolerance in peripheral T cells. Aire -deficient mice were crossed with mice of a uniform major histocompatibility complex (MHC) haplotype and genetic background carrying specific genetic defects in one of four distinct peripheral tolerance mechanisms: activation-induced cell death ( Fasl gld/gld ), anergy and requirement for CD28 costimulation ( Cblb −/− ), inhibition of ICOS and T FH cells ( Rc3h1 san/san ), or decreased numbers of Foxp3 + T regulatory cells ( Card11 unm/unm ). Cblb -deficiency was unique among these four in precipitating rapid clinical autoimmune disease when combined with Aire -deficiency, resulting in autoimmune exocrine pancreatitis with median age of survival of only 25 d. Massive lymphocytic infiltration selectively destroyed most of the exocrine acinar cells of the pancreas and submandibular salivary gland, and CD4 + and CD8 + subsets were necessary and sufficient to transfer the disease. Intrinsic regulation of peripheral T cells by CBL-B thus serves a uniquely critical role as a failsafe against clinical onset of autoimmune disease in AIRE deficiency, and multiple peripheral tolerance mechanisms may need to fail before onset of clinical autoimmunity to many organs.
Publisher: Annual Reviews
Date: 04-1992
DOI: 10.1146/ANNUREV.IY.10.040192.002421
Abstract: Understanding the mechanism of immunological tolerance to self-antigens remains a fundamental problem in immunology. Transgenic mice carrying rearranged antigen-receptor genes have provided a window into the events involved in this process, by allowing the development and fate of antigen-specific lymphocytes to be followed in vivo. In the B-cell lineage, as in T cells, self-reactive cells have been found to undergo several distinct fates in vivo: they can be physically eliminated, functionally inactivated, or they can persist unchanged or become activated. As discussed in this review, direct visualization of the fate of self-reactive cells resolves one of the key issues in tolerance. Achieving a precise understanding of the cellular and molecular events leading to lymphocyte deletion, anergy, or activation nevertheless remains a challenge for the future.
Publisher: Springer US
Date: 2007
Publisher: Wiley
Date: 03-08-2018
DOI: 10.1002/ART.40539
Abstract: Rheumatoid factors (RFs) are associated with systemic disease in primary Sjögren's syndrome (SS) and may be pathogenic as mixed cryoglobulins. Current detection methods cannot resolve RFs at a molecular level. This study was undertaken to perform the first proteomic and transcriptomic analysis of secreted and membrane-bound IgM-RF in primary SS and identify unique heavy-chain peptide signatures for RF clonotype tracking. Purified heavy chains of serum RFs from 15 patients with primary SS were subjected to de novo mass spectrometric sequencing. The circulating B cell Ig repertoire was determined by massively parallel sequencing of IGH RNA from matched peripheral blood mononuclear cells (n = 7). RF-specific heavy-chain third complementarity-determining region (CDR3) peptides were identified by searching RF heavy-chain peptide sequences against the corresponding IGH RNA sequence libraries. Heavy-chain CDR3 peptides were used as biomarkers to track serum RF clonotypes using quantitative multiple reaction monitoring. Serum RFs were clonally restricted and composed of shared sets of IgM heavy-chain variable region (Ig V Cryoprecipitable RF clonotypes linked to vasculitis in primary SS have different molecular profiles than nonprecipitating RFs, suggesting different underlying mechanisms of production. The combined omics workflow presented herein provides molecular biomarkers for tracking and removal of pathogenic RF clones.
Publisher: Oxford University Press (OUP)
Date: 30-05-2006
Abstract: The MRL-lpr/lpr mouse strain is a commonly used model of the human autoimmune disease systemic lupus erythematosus (SLE). Although much is known about the contribution of the lpr Fas mutation to B cell tolerance breakdown, the role of the genetic background of the MRL strain itself is less well explored. In this study, we use the MD4 anti-hen egg lysozyme Ig (IgHEL) transgenic system to explore B cell function in MRL+/+ and non-autoimmune mice. We demonstrate that MRL IgHEL B cells show spontaneous hyperactivity in the absence of self-antigen, which is associated with low total B cell numbers but an expansion of the marginal zone B cell population. However, B cell anergy is normal in the presence of soluble lysozyme [soluble hen egg lysozyme (sHEL)], and MRL IgHEL B cells undergo normal elimination in the presence of sHEL when competing with a polyclonal C57BL/6 B cell repertoire. We conclude that B cell hyperactivity may contribute to the autoimmune phenotype of MRL+/+ and MRL-lpr/lpr strains when it initiates antibody responses to rare or sequestered antigens that are below the threshold for tolerance induction, but that there is no B cell intrinsic defect in anergy in MRL mice.
Publisher: The American Association of Immunologists
Date: 15-10-2006
DOI: 10.4049/JIMMUNOL.177.8.5155
Abstract: Coligation of CD21 with BCR on the surface of B cells provides a costimulatory signal essential for efficient Ab responses to T-dependent Ags. To achieve this, Ag must be directly linked to C3 fragments, but how this occurs in vivo is not fully understood. Using BCR transgenic mice, we demonstrated that C3 was deposited on the surface of B cells following both high- and moderate-affinity Ag binding. This was dependent on the specific binding of IgM to the BCR-bound Ag and can occur independently of soluble immune complex formation. Based on these data, we propose a novel model in which immune complexes can form directly on the surface of the B cell following Ag binding. This model has implications for our understanding of B lymphocyte activation.
Publisher: Oxford University Press (OUP)
Date: 12-2005
Abstract: Many of the proteins and their encoding genes involved in spermatogenesis are unknown, making the specific diagnosis and treatment of infertility in males difficult and highlighting the importance of identifying new genes that are involved in spermatogenesis. Through genome-wide chemical mutagenesis using N-ethyl-N-nitrosourea (ENU) and a three-generation breeding scheme to isolate recessive mutations, we have identified mouse lines with a range of abnormalities relevant to human male fertility. Abnormal phenotypes included hypospermatogenesis, Sertoli cell-only (SCO) seminiferous tubules, germ-cell arrest and abnormal spermiogenesis and were accompanied, in some, with abnormal serum levels of reproductive hormones. In total, from 65 mouse lines, 14 showed a reproductive phenotype consistent with a recessive mutation. This study shows that it is feasible to use ENU mutagenesis as an effective and rapid means of generating mouse models relevant to furthering our understanding of human male infertility. Spermatozoa and genomic DNA from all mouse lines, including those with abnormal reproductive tract parameters, have been cryopreserved for the regeneration of lines as required. This repository will form a valuable resource for the identification and analysis of key regulators of multiple aspects of male fertility.
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.IMMUNI.2013.01.011
Abstract: Accumulation of T follicular helper (Tfh) cells and proinflammatory cytokines drive autoantibody-mediated diseases. The RNA-binding protein Roquin-1 (Rc3h1) represses the inducible costimulator ICOS and interferon-γ (IFN-γ) in T cells to prevent Tfh cell accumulation. Unlike Rc3h1(san) mice with a mutation in the ROQ domain of Roquin-1, mice lacking the protein, paradoxically do not display increased Tfh cells. Here we have analyzed mice with mutations that eliminate the RING domain from Roquin-1 or its paralog, Roquin-2 (Rc3h2). RING or ROQ mutations both disrupted Icos mRNA regulation by Roquin-1, but, unlike the ROQ mutant that still occupied mRNA-regulating stress granules, RING-deficient Roquin-1 failed to localize to stress granules and allowed Roquin-2 to compensate in the repression of ICOS and Tfh cells. These paralogs also targeted tumor necrosis factor (TNF) in nonlymphoid cells, ameliorating autoantibody-induced arthritis. The Roquin family emerges as a posttranscriptional brake in the adaptive and innate phases of antibody responses.
Publisher: Public Library of Science (PLoS)
Date: 04-11-2011
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1016/J.CELL.2015.07.055
Abstract: Dynamic interactions between B and T cells underpin the development of adaptive humoral immune responses to infections and vaccines. Recent advances in the molecular and spatiotemporal control of these interactions during primary responses have contributed greatly to elucidating the molecular pathogenesis of numerous immunodeficiency and autoimmune diseases. The next challenge is to determine how and where memory B and T cells interact during secondary responses to facilitate the rapid and robust response that characterizes anamnestic immunity.
Publisher: Rockefeller University Press
Date: 17-08-1998
Abstract: Peripheral tolerance mechanisms normally prevent delivery of T cell help to anergic self-reactive B cells that accumulate in the T zones of spleen and lymph nodes. Chronic exposure to self-antigens desensitizes B cell antigen receptor (BCR) signaling on anergic B cells so that they are not stimulated into clonal expansion by CD4+ T cells but instead are eliminated by Fas (CD95)-induced apoptosis. Because a range of BCR-induced signals and responses are repressed in anergic B cells, it is not known which of these are critical to regulate for Fas-mediated peripheral tolerance. Display of the costimulatory molecule, B7.2 (CD86), represents a potentially important early response to acute BCR engagement that is poorly induced by antigen on anergic B cells. We show here that restoring B7.2 expression on tolerant B cells using a constitutively expressed B7.2 transgene is sufficient to prevent Fas-mediated deletion and to trigger extensive T cell–dependent clonal expansion and autoantibody secretion in the presence of specific T cells. Dysregulated expression of B7.2 on tolerant B cells caused a more extreme reversal of peripheral tolerance than that caused by defects in Fas or Fas ligand, and resulted in T cell–dependent clonal expansion and antibody secretion comparable in magnitude to that made by foreign antigen-specific B cells. These findings demonstrate that repression of B7.2 is critical to eliminate autoreactive B cells by Fas in B cell–T cell interactions. The possible role of B7.2 dysregulation in systemic autoimmune diseases is discussed.
Publisher: Proceedings of the National Academy of Sciences
Date: 19-03-1996
Abstract: Immunological self-tolerance is ensured by eliminating or inhibiting self-reactive lymphocyte clones, creating physical or functional holes in the B- and T-lymphocyte antigen receptor repertoires. The nature and size of these gaps in our immune defenses must be balanced against the necessity of mounting rapid immune responses to an everchanging array of foreign pathogens. To achieve this balance, only a fraction of particularly hazardous self-reactive clones appears to be physically eliminated from the repertoire in a manner that fully prevents their recruitment into an antimicrobial immune response. Many self-reactive cells are retained with a variety of conditional and potentially flexible restraints: (i) their ability to be triggered by antigen is diminished by mechanisms that tune down signaling by their antigen receptors, (ii) their ability to carry out inflammatory effector functions can be inhibited, and (iii) their capacity to migrate and persist is constrained. This balance between tolerance and immunity can be shifted, altering susceptibility to autoimmune disease and to infection by genetic or environmental differences either in the way antigens are presented, in the tuning molecules that adjust triggering set points for lymphocyte responses to antigen, or in the effector molecules that eliminate, retain, or expand particular clones.
Publisher: Elsevier
Date: 1995
Publisher: Cold Spring Harbor Laboratory
Date: 1999
Publisher: Elsevier BV
Date: 03-2015
DOI: 10.1016/J.AUTREV.2014.10.021
Abstract: Whole exome sequencing (WES) is a widely used strategy for detection of protein coding and splicing variants associated with inherited diseases. Many studies have shown that the strategy has been broad and proficient due to its ability in detecting a high proportion of disease causing variants, using only a small portion of the genome. In this review we outline the main steps involved in WES, the comprehensive analysis of the massive data obtained including the genomic capture, lification, sequencing, alignment, curating, filtering and genetic analysis to determine the presence of candidate variants with potential pathogenic/functional effect. Further, we propose that the multiple autoimmune syndrome, an extreme phenotype of autoimmune disorders, is a very well suited trait to tackle genomic variants of major effect underpinning the lost of self-tolerance.
Publisher: Springer Science and Business Media LLC
Date: 05-2005
DOI: 10.1038/NATURE03555
Abstract: Despite the sequencing of the human and mouse genomes, few genetic mechanisms for protecting against autoimmune disease are currently known. Here we systematically screen the mouse genome for autoimmune regulators to isolate a mouse strain, sanroque, with severe autoimmune disease resulting from a single recessive defect in a previously unknown mechanism for repressing antibody responses to self. The sanroque mutation acts within mature T cells to cause formation of excessive numbers of follicular helper T cells and germinal centres. The mutation disrupts a repressor of ICOS, an essential co-stimulatory receptor for follicular T cells, and results in excessive production of the cytokine interleukin-21. sanroque mice fail to repress diabetes-causing T cells, and develop high titres of autoantibodies and a pattern of pathology consistent with lupus. The causative mutation is in a gene of previously unknown function, roquin (Rc3h1), which encodes a highly conserved member of the RING-type ubiquitin ligase protein family. The Roquin protein is distinguished by the presence of a CCCH zinc-finger found in RNA-binding proteins, and localization to cytosolic RNA granules implicated in regulating messenger RNA translation and stability.
Publisher: Public Library of Science (PLoS)
Date: 24-05-2012
Publisher: Elsevier BV
Date: 09-2016
Publisher: Proceedings of the National Academy of Sciences
Date: 20-08-2021
Abstract: The experiments here advance understanding of the function of the SAMD9L gene and protein in innate immune mechanisms in resisting virus infection and in the pathogenesis of inflammatory, hematological, and neurological disorders. The clinical syndrome defined in two children with de novo truncating SAMD9L mutations expands the phenotypes in this newly recognized autoinflammatory disorder. Analysis of cells expressing normal or mutant SAMD9L reveals the protein represses protein translation, with the truncating mutations greatly exaggerating this activity. The experiments find equally potent gain of function caused by the truncating mutations or a recurrent missense mutation associated with clinically milder ataxia and pancytopenia syndromes, demonstrating that erse clinical manifestations can arise from mutations that appear cell-biologically equivalent.
Publisher: Springer Science and Business Media LLC
Date: 05-10-2008
DOI: 10.1038/NI.1662
Publisher: Cold Spring Harbor Laboratory
Date: 20-10-2022
DOI: 10.1101/2022.10.19.512954
Abstract: Emerging variants of concern (VOCs) are threatening to limit the effectiveness of SARS-CoV-2 monoclonal antibodies and vaccines currently used in clinical practice broadly neutralizing antibodies and strategies for their identification are therefore urgently required. Here we demonstrate that broadly neutralizing antibodies can be isolated from peripheral blood mononuclear cells (PBMCs) of convalescent patients using SARS-CoV-2 receptor binding domains (RBDs) carrying epitope-specific mutations. This is exemplified by two human antibodies, GAR05, binding to epitope class 1, and GAR12, binding to a new epitope class 6 (located between class 3 and class 5). Both antibodies broadly neutralize VOCs, exceeding the potency of the clinical monoclonal sotrovimab (mAb S309) by orders of magnitude. They also provide potent prophylactic and therapeutic in vivo protection of hACE2 mice against viral challenge. Our results indicate that exposure to Wuhan SARS-CoV-2 induces antibodies that maintain potent and broad neutralization against emerging VOCs using two unique strategies: either by targeting the ergent class 1 epitope in a manner resistant to VOCs (ACE2 mimicry, as illustrated by GAR05 and mAbs P2C-1F11/S2K14) or alternatively, by targeting rare and highly conserved epitopes, such as the new class 6 epitope identified here (as illustrated by GAR12). Our results provide guidance for next generation monoclonal antibody development and vaccine design.
Publisher: Rockefeller University Press
Date: 16-03-1998
Abstract: Engagement of antigen receptors on mature B lymphocytes is known to block cell entry into lymphoid follicles and promote accumulation in T cell zones, yet the molecular basis for this change in cell distribution is not understood. Previous studies have shown that follicular exclusion requires a threshold level of antigen receptor engagement combined with occupancy of follicles by B cells without equivalent receptor engagement. The possibility has been raised that follicular composition affects B cell positioning by altering the amount of available antigen and the degree of receptor occupancy. Here we show that follicular composition affects migration of mature B cells under conditions that are independent of antigen receptor occupancy. B cells deficient in the negative regulatory protein tyrosine phosphatase, SHP1, which have elevated intracellular signaling by the B cell receptor, are shown to accumulate in the T zone in the absence of their specific antigen. Follicular exclusion of SHP1–deficient B cells was found to be conditional on the presence of excess B cells that lack elevated intracellular signaling, and was not due to a failure of SHP-1–deficient cells to mature and express the follicle-homing chemokine receptor Burkitt's lymphoma receptor 1. These findings strongly suggest that signals that are negatively regulated by SHP1 promote B cell localization in T cell zones by reducing competitiveness for follicular entry, and provide further evidence that follicular composition influences the positioning of antigen-engaged B cells.
Publisher: Elsevier BV
Date: 08-1997
DOI: 10.1016/S1074-7613(00)80528-2
Abstract: T cell receptor (TCR) transgenic mice specific for hen egg lysozyme (HEL) were crossed with mice expressing HEL on the thyroid epithelium, on pancreatic islet beta cells, or systemically. Depending on the pattern of HEL expression, deletion of double-positive thymocytes ranged from minimal to complete, and peripheral CD4 cells exhibited graded reduction in TCR expression, in vitro responsiveness, and in vivo helper ability. CD4 cells were least tolerant in TCR/thyroid-HEL and TCR/islet-HEL mice, which developed an extensive lymphocytic thyroiditis or insulitis that nevertheless did not eliminate HEL-expressing endocrine cells. Autoreactive CD4 clones thus escape the thymus under a range of circumstances, retain sufficient function to initiate subclinical autoimmune inflammation when self-antigens are concentrated in the thyroid or pancreas, and may regulate progression of subclinical inflammation to destructive autoimmune disease.
Publisher: Wiley
Date: 08-2005
DOI: 10.1111/J.1440-1711.2005.01353.X
Abstract: A plethora of genes involved in murine B and T cell development have been identified, and developmental pathways within the primary lymphoid tissues have been well delineated. The generation of a functional, but non-self reacting lymphocyte repertoire results from the completion of several checkpoints during lymphocyte development and competition for survival factors in the periphery. Improved knowledge of these developmental checkpoints and homeostatic mechanisms is critical for understanding human immunodeficiency, leukaemia/lymphoma and autoimmunity, which are conditions where checkpoints and homeostasis are likely to be deregulated.
Publisher: Elsevier BV
Date: 04-2000
DOI: 10.1016/S0952-7915(99)00076-X
Abstract: Immunologists are already comfortable with the need for monitoring many different gene products simultaneously. It is a common challenge to remember what CD-one-hundred-and-something is, and an ever-increasing number of colours are required for identification on the flow cytometer. Gene expression arrays now offer the possibility of extending this approach beyond the cell surface and expanding it dramatically to survey the entire catalogue of gene transcripts in a lymphoid cell.
Publisher: Springer Berlin Heidelberg
Date: 1989
Publisher: Proceedings of the National Academy of Sciences
Date: 12-06-2017
Abstract: T cells are required for control of many intracellular infections, and a critical component of T cell immunity is the proliferative expansion of effector T cells upon stimulation. Using a forward-based genetic screen, we identify the mouse Etaa1 gene as critically important for T cell proliferative expansion after vaccination and during infection. Consistent with recent findings that ETAA1 prevents DNA damage during proliferation, our data demonstrate elevated DNA damage within Etaa1 -deficient effector T cells, which likely leads to cell death. This phenotype is restricted to effector T cell proliferation, with T cell development and other immune parameters remaining normal. Thus, ETAA1 may represent a novel drug target to selectively suppress pathological T cell responses in transplantation or autoimmunity.
Publisher: American Association for Cancer Research (AACR)
Date: 07-2018
DOI: 10.1158/1538-7445.AM2018-LB-121
Abstract: Responses to immune checkpoint inhibitors (CPI) may vary between in iduals because of differences in somatic mutations in the tumour and/or germ-line differences in immunological tolerance. To explore the latter, this ongoing study evaluates patients with metastatic non-small cell lung cancer treated with single agent PD-1 or PD-L1 inhibitors from an active treatment pool of over 200 patients. Rare and common germ-line DNA variants are analysed in exceptional responders and non-responders by whole genome sequencing (Illumina HiSeq X Ten). Exceptional responders are defined as in iduals with sustained partial (& months) or complete response per RECIST criteria with concurrent autoimmune toxicity, implying systemic immune activation. In these in iduals, the cumulative burden of rare and common variants in a curated list of immune tolerance genes is analysed and compared to the Medical Genome Reference Bank, comprising whole genome sequences of 1146 well-elderly in iduals. Comparisons are made with Fisher Exact test. Recurrent rare variants (Exome Aggregation Consortium (ExAC) frequency & %) were found within responders sequenced to date (n=10), including variant A, a frameshift mutation in a protein associated with autoimmunity, not present in ExAC with Genome Aggregation Database (GnomAD) frequency 0.0002% (P & 0.0001). Multiple common variants (ExAC & %) are more frequent within this cohort compared with population standard, for ex le variant B, a missense mutation within a DNA-repair protein that has ExAC allelic frequency of 2.5% and is present in 30% of our cohort (P = .013). Polygenic risk scores for diseases of impaired immune tolerance within exceptional responders are distinct from control groups. Further analyses of immune-related variants within anti-PD-1/PD-L1 responders and control groups will be presented. Preliminary findings suggest in iduals harbouring damaging variants in genes promoting immune tolerance are more responsive to PD-1/PD-L1 inhibitors because basal immune activation is higher, requiring greater reliance on inhibitory checkpoints to maintain homeostasis. Ordinarily, this would be clinically undetectable, however the addition of a pharmacological CPI may more effectively break immune tolerance in this primed environment. Citation Format: Megan B. Barnet, Katherine J. Jackson, Bo Gao, Adnan M. Nagrial, Michael J. Boyer, Wendy A. Cooper, Rina Hui, Anthony Linton, Martin H. Tattersall, Greg Gibson, Jonathan Cebon, Georgina V. Long, Alexander M. Menzies, Richard A. Scolyer, Paul Lacaze, Robert Brink, Timothy Peters, Mark Cowley, Velimir Gayevskiy, David M. Thomas, Mark Pinese, Prunella Blinman, Steven Kao, Christopher C. Goodnow. Exploring the germ-line contribution to exceptional response to PD-1/PD-L1 inhibition in patients with metastatic non-small-cell lung cancer by whole genome sequencing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018 2018 Apr 14-18 Chicago, IL. Philadelphia (PA): AACR Cancer Res 2018 (13 Suppl):Abstract nr LB-121.
Publisher: Springer Science and Business Media LLC
Date: 08-1988
DOI: 10.1038/334676A0
Abstract: Immunological tolerance has been demonstrated in double-transgenic mice expressing the genes for a neo-self antigen, hen egg lysozyme, and a high affinity anti-lysozyme antibody. The majority of anti-lysozyme B-cells did not undergo clonal deletion, but were no longer able to secrete anti-lysozyme antibody and displayed markedly reduced levels of surface IgM while continuing to express high levels of surface IgD. These findings indicate that self tolerance may result from mechanisms other than clonal deletion, and are consistent with the hypothesis that IgD may have a unique role in B-cell tolerance.
Publisher: Springer Science and Business Media LLC
Date: 15-02-2001
DOI: 10.1038/35057020
Abstract: The outstanding problems facing immunology are whole system issues: curing allergic and autoimmune disease and developing vaccines to stimulate stronger immune responses against pathogenic organisms and cancer. We hope that the human genome sequence will reveal the molecular checks and balances that ensure both an effective immunogenic response against pathogenic microorganisms and a suitably tolerogenic response to self antigens and innocuous environmental antigens. Three synergistic approaches--sequence homology searches, messenger RNA expression profiling on microarrays, and mutagenesis in mice--provide the best opportunities to reveal, in the genome sequence, key proteins and pathways for targeting by new immunomodulatory treatments.
Publisher: Oxford University Press (OUP)
Date: 1992
Abstract: To analyse mechanisms of immunological self-tolerance, a detailed comparison of the development and fate of lysozyme-specific B lymphocytes was carried out in transgenic mice expressing rearranged anti-lysozyme IgM/IgD Ig transgenes in the absence or presence of an additional transgene encoding lysozyme itself. In the absence of lysozyme, B cell development, localization, and differential expression of transgene-encoded IgM and IgD occurred in the normal sequence in Ig transgenic mice, establishing that these animals provide a physiological model for studies of B cell selection in vivo. By contrast, in lysozyme-expressing double-transgenic mice, tolerant lysozyme-reactive B cells persisted within the follicular mantle zones in the spleen, lymph nodes, and Peyer's patches, but were eliminated from the splenic marginal zones. It could be shown that lysozyme-binding and induction of tolerance occurred as soon as surface Ig was expressed on immature B cells in the bone marrow of the double-transgenic mice although this did not prevent maturation, emigration from the bone marrow, and localization in peripheral lymphoid follicles. These findings, together with recent ex les of aborted maturation of self-reactive B cells, indicate two functionally distinct antigen receptor signalling events in immature B cells and suggest a unique role for the follicular microenvironment.
Publisher: Elsevier BV
Date: 12-2004
DOI: 10.1016/J.IMMUNI.2004.10.014
Abstract: The cause of common polygenic autoimmune diseases is not understood because of genetic and cellular complexity. Here, we pinpoint the action of a subset of autoimmune susceptibility loci in the NOD mouse strain linked to D1mit181, D2mit490, D7mit101, and D15mit229, which cause a generalized resistance to thymic deletion in vivo that applies equally to Aire-induced organ-specific gene products in the thymic medulla and to systemic antigens expressed at high levels throughout the thymus and affects CD4(+), CD4(+)8(+), and CD4(+)25(+) thymocytes. Resistance to thymic deletion does not reflect a general deficit in TCR signaling to calcineurin- or ERK-induced genes, imbalance in constitutive regulators of apoptosis, nor excessive signaling to prosurvival genes but is distinguished by failure to induce the proapoptotic gene and protein, Bim, during in vivo encounter with high-avidity autoantigen. These findings establish defects in thymic deletion and Bim induction as a key mechanism in the pathogenesis of autoimmunity.
Publisher: Rockefeller University Press
Date: 17-04-2000
Abstract: Signal transduction through the B cell antigen receptor (BCR) is altered in B cells that express a receptor that recognizes self-antigen. To understand the molecular basis for the change in signaling in autoreactive B cells, a transgenic model was used to isolate a homogeneous population of tolerant B lymphocytes. These cells were compared with a similar population of naive B lymphocytes. We show that the BCR from naive B cells enters a detergent-insoluble domain of the cell within 6 s after antigen binding, before a detectable increase in BCR phosphorylation. This fraction appears to be important for signaling because it is enriched for lyn kinase but lacks CD45 tyrosine phosphatase and because the BCR that moves into this domain becomes more highly phosphorylated. Partitioning of the BCR into this fraction is unaffected by src family kinase inhibition. Tolerant B cells do not efficiently partition the BCR into the detergent-insoluble domain, providing an explanation for their reduced tyrosine kinase activation and calcium flux in response to antigen. These results identify an early, regulated step in antigen receptor signaling and self-tolerance.
Publisher: Rockefeller University Press
Date: 16-12-2019
DOI: 10.1084/JEM.20191336
Abstract: Antibody-mediated autoimmune diseases are a major health burden. However, our understanding of how self-reactive B cells escape self-tolerance checkpoints to secrete pathogenic autoantibodies remains incomplete. Here, we demonstrate that patients with monogenic immune dysregulation caused by gain-of-function mutations in PIK3CD, encoding the p110δ catalytic subunit of phosphoinositide 3-kinase (PI3K), have highly penetrant secretion of autoreactive IgM antibodies. In mice with the corresponding heterozygous Pik3cd activating mutation, self-reactive B cells exhibit a cell-autonomous subversion of their response to self-antigen: instead of becoming tolerized and repressed from secreting autoantibody, Pik3cd gain-of-function B cells are activated by self-antigen to form plasmablasts that secrete high titers of germline-encoded IgM autoantibody and hypermutating germinal center B cells. However, within the germinal center, peripheral tolerance was still enforced, and there was selection against B cells with high affinity for self-antigen. These data show that the strength of PI3K signaling is a key regulator of pregerminal center B cell self-tolerance and thus represents a druggable pathway to treat antibody-mediated autoimmunity.
Publisher: Proceedings of the National Academy of Sciences
Date: 15-02-2000
Abstract: Antigen receptors (BCRs) on developing B lymphocytes play two opposing roles—promoting survival of cells that may later bind a foreign antigen and inhibiting survival of cells that bind too strongly to self-antigens. It is not known how these opposing outcomes are signaled by BCRs on immature B cells. Here we analyze the effect of a null mutation in the Syk tyrosine kinase on maturing B cells displaying a transgene-encoded BCR that binds hen egg lysozyme (HEL). In the absence of HEL antigen, HEL-specific BCRs are expressed normally on the surface of Syk-deficient immature B-lineage cells, but this fails to promote maturation beyond the earliest stages of B-lineage commitment. Binding of HEL antigen, nevertheless, triggers phosphorylation of CD79α/β BCR subunits and modulation of receptors from the surface in Syk-deficient cells, but it cannot induce an intracellular calcium response. Continuous binding of low- or high-avidity forms of HEL, expressed as self-antigens, fails to restore the signal needed for maturation. Compared with the effects in the same system of null mutations in other BCR signaling elements, such as CD45 and Lyn kinase, these results indicate that Syk is essential for transmitting a signal that initiates the program of B-lymphocyte maturation.
Publisher: Springer Science and Business Media LLC
Date: 04-1997
DOI: 10.1038/386855A0
Abstract: An increase in the intracellular calcium ion concentration ([Ca2+]i) controls a erse range of cell functions, including adhesion, motility, gene expression and proliferation. Calcium signalling patterns can occur as single transients, repetitive oscillations or sustained plateaux, but it is not known whether these patterns are responsible for encoding the specificity of cellular responses. We report here that the litude and duration of calcium signals in B lymphocytes controls differential activation of the pro-inflammatory transcriptional regulators NF-kappaB, c-Jun N-terminal kinase (JNK) and NFAT. NF-kappaB and JNK are selectively activated by a large transient [Ca2+]i rise, whereas NFAT is activated by a low, sustained Ca2+ plateau. Differential activation results from differences in the Ca2+ sensitivities and kinetic behaviour of the three pathways. Our results show how downstream effectors can decode information contained in the litude and duration of Ca2+ signals, revealing a mechanism by which a multifunctional second messenger such as Ca2+ can achieve specificity in signalling to the nucleus.
Publisher: Elsevier BV
Date: 05-2011
Publisher: Springer Science and Business Media LLC
Date: 16-09-2015
DOI: 10.1038/NATURE15541
Abstract: Intracellular lipopolysaccharide from Gram-negative bacteria including Escherichia coli, Salmonella typhimurium, Shigella flexneri, and Burkholderia thailandensis activates mouse caspase-11, causing pyroptotic cell death, interleukin-1β processing, and lethal septic shock. How caspase-11 executes these downstream signalling events is largely unknown. Here we show that gasdermin D is essential for caspase-11-dependent pyroptosis and interleukin-1β maturation. A forward genetic screen with ethyl-N-nitrosourea-mutagenized mice links Gsdmd to the intracellular lipopolysaccharide response. Macrophages from Gsdmd(-/-) mice generated by gene targeting also exhibit defective pyroptosis and interleukin-1β secretion induced by cytoplasmic lipopolysaccharide or Gram-negative bacteria. In addition, Gsdmd(-/-) mice are protected from a lethal dose of lipopolysaccharide. Mechanistically, caspase-11 cleaves gasdermin D, and the resulting amino-terminal fragment promotes both pyroptosis and NLRP3-dependent activation of caspase-1 in a cell-intrinsic manner. Our data identify gasdermin D as a critical target of caspase-11 and a key mediator of the host response against Gram-negative bacteria.
Publisher: Wiley
Date: 04-2002
DOI: 10.1046/J.1440-1711.2002.01074.X
Abstract: Genes outside the MHC create a general susceptibility to autoimmunity in non-obese diabetic (NOD) mice. In this study, we describe marked differences in dendritic cell generation, in vitro, caused by non-MHC NOD genes. Bone marrow cells from NOD.H-2k mice cultured in vitro with GM-CSF and IL-4 generated a reduced yield of dendritic cells when compared to bone marrow cells from B10.H-2k mice. This was due to failure to pass through successive rounds of cell ision and elevated levels of apoptosis in NOD.H-2k precursor cells. This aberrant response to GM-CSF and IL-4 was unique to the NOD.H-2k background when compared to bone marrow cells from other H-2k congenic strains, and coculture experiments showed that it was cell-autonomous. Overall, the results described in this study demonstrate a striking effect of non-MHC NOD genes on dendritic cell generation from myeloid precursors derived from the NOD.H-2k strain. These results identify a useful genetic model to explore the regulation of dendritic cell formation. Conceivably, the dysregulation of the dendritic cell system described here may contribute to the generalized defects in self-tolerance in the NOD strain.
Publisher: Wiley
Date: 24-11-2016
DOI: 10.1038/ICB.2015.95
Abstract: Thymocytes that bind strongly to self-antigens are prevented from becoming naive T cells by several mechanisms. They undergo clonal deletion at two stages of development wave 1 in immature thymocytes lacking the medulla-homing chemokine receptor, CCR7, or wave 2 in more mature CCR7(+) thymocytes. Alternatively, self-reactive thymocytes upregulate Foxp3 to become T-regulatory cells. Here, we describe the differential timing of the two waves of deletion and Foxp3 upregulation relative to the immature proliferating stage. Proliferating thymocytes were pulse-labeled in normal C57BL/6 mice with 5-ethynyl-2'-deoxyuridine (EdU). Thymocytes progressed into wave 1 (CCR7(-)) and wave 2 (CCR7(+)) of clonal deletion ~2 and 5 days after proliferation, respectively. Foxp3 upregulation occurred between 4 and 8 days after proliferation, predominantly in thymocytes with a Helios(+) CCR7(+) phenotype. These findings establish a timeline that suggests that wave 1 of clonal deletion occurs in the thymic cortex, whereas wave 2 and Foxp3 upregulation both occur in the thymic medulla.
Publisher: Elsevier BV
Date: 04-1998
DOI: 10.1016/S1074-7613(00)80554-3
Abstract: A B lymphocyte hyperactivity syndrome resembling systemic lupus erythematosus characterizes mice lacking the src-family kinase Lyn. Lyn is not required to initiate B cell antigen receptor (BCR) signaling but is an essential inhibitory component. lyn-/- B cells have a delayed but increased calcium flux and exaggerated negative selection responses in the presence of antigen and spontaneous hyperactivity in the absence of antigen. As in invertebrates, genetic effects of loci with only one functional allele can be used to analyze signaling networks in mice, demonstrating that negative regulation of the BCR is a complex quantitative trait in which Lyn, the coreceptor CD22, and the tyrosine phosphatase SHP-1 are each limiting elements. The biochemical basis of this complex trait involves a pathway requiring Lyn to phosphorylate CD22 and recruit SHP-1 to the CD22/BCR complex.
Publisher: Rockefeller University Press
Date: 17-02-2014
DOI: 10.1084/JEM.20131424
Abstract: MYD88L265P has recently been discovered as an extraordinarily frequent somatic mutation in benign monoclonal IgM gammopathy, Waldenström’s macroglobulinemia, and diffuse large B cell lymphoma. In this study, we analyze the consequences for antigen-activated primary B cells of acquiring MYD88L265P. The mutation induced rapid B cell ision in the absence of exogenous TLR ligands and was inhibited by Unc93b13d mutation and chloroquine or TLR9 deficiency, indicating continued dependence on upstream TLR9 activation. Proliferation and NF-κB activation induced by MYD88L265P were nevertheless rapidly countered by the induction of TNFAIP3, an NF-κB inhibitor frequently inactivated in MYD88L265P–bearing lymphomas, and extinguished by Bim-dependent apoptosis. MYD88L265P caused self-reactive B cells to accumulate in vivo only when apoptosis was opposed by Bcl2 overexpression. These results reveal checkpoints that fortify TLR responses against aberrant B cell proliferation in response to ubiquitous TLR and BCR self-ligands and suggest that tolerance failure requires the accumulation of multiple somatic mutations.
Publisher: Elsevier BV
Date: 04-1999
Publisher: Springer Science and Business Media LLC
Date: 18-09-2019
DOI: 10.1038/S41590-019-0492-0
Abstract: Resisting and tolerating microbes are alternative strategies to survive infection, but little is known about the evolutionary mechanisms controlling this balance. Here genomic analyses of anatomically modern humans, extinct Denisovan hominins and mice revealed a TNFAIP3 allelic series with alterations in the encoded immune response inhibitor A20. Each TNFAIP3 allele encoded substitutions at non-catalytic residues of the ubiquitin protease OTU domain that diminished IκB kinase-dependent phosphorylation and activation of A20. Two TNFAIP3 alleles encoding A20 proteins with partial phosphorylation deficits seemed to be beneficial by increasing immunity without causing spontaneous inflammatory disease: A20 T108A I207L, originating in Denisovans and introgressed in modern humans throughout Oceania, and A20 I325N, from an N-ethyl-N-nitrosourea (ENU)-mutagenized mouse strain. By contrast, a rare human TNFAIP3 allele encoding an A20 protein with 95% loss of phosphorylation, C243Y, caused spontaneous inflammatory disease in humans and mice. Analysis of the partial-phosphorylation A20 I325N allele in mice revealed diminished tolerance of bacterial lipopolysaccharide and poxvirus inoculation as tradeoffs for enhanced immunity.
Publisher: The American Association of Immunologists
Date: 15-02-2011
Abstract: The E3 ubiquitin ligase Cbl-b regulates T cell activation thresholds and has been associated with protecting against type 1 diabetes, but its in vivo role in the process of self-tolerance has not been examined at the level of potentially autoaggressive CD4+ T cells. In this study, we visualize the consequences of Cbl-b deficiency on self-tolerance to lysozyme Ag expressed in transgenic mice under control of the insulin promoter (insHEL). By tracing the fate of pancreatic islet-reactive CD4+ T cells in prediabetic 3A9-TCR × insHEL double-transgenic mice, we find that Cbl-b deficiency contrasts with AIRE or IL-2 deficiency, because it does not affect thymic negative selection of islet-reactive CD4+ cells or the numbers of islet-specific CD4+ or CD4+Foxp3+ T cells in the periphery, although it decreased differentiation of inducible regulatory T cells from TGF-β–treated 3A9-TCR cells in vitro. When removed from regulatory T cells and placed in culture, Cblb-deficient islet-reactive CD4+ cells reveal a capacity to proliferate to HEL Ag that is repressed in wild-type cells. This latent failure of T cell anergy is, nevertheless, controlled in vivo in prediabetic mice so that islet-reactive CD4+ cells in the spleen and the pancreatic lymph node of Cblb-deficient mice show no evidence of increased activation or proliferation in situ. Cblb deficiency subsequently precipitated diabetes in most TCR:insHEL animals by 15 wk of age. These results reveal a role for peripheral T cell anergy in organ-specific self-tolerance and illuminate the interplay between Cblb-dependent anergy and other mechanisms for preventing organ-specific autoimmunity.
Publisher: Elsevier BV
Date: 10-2006
DOI: 10.1016/J.COI.2006.07.011
Abstract: In random chemical mutagenesis, gene discovery is driven by phenotypes rather than by hypotheses. A standard dose of N-ethyl-N-nitrosourea results in approximately 30 coding mutations in male G1 mice, of which approximately 4 can be propagated to homozygosity in 3 generations. In recent years, large-scale screens of such G3 mice for phenotypes of interest to immunologists have revealed clues to the number of genes responsible for key immune responses, such as innate recognition of pathogens and autoantibody production. More than 20 of the phenotypes that exhibit a simple (Mendelian) pattern of inheritance have been mapped. Novel alleles have revealed new pathways of host defense, allergy and autoimmunity.
Publisher: Springer Science and Business Media LLC
Date: 10-2000
DOI: 10.1038/35036673
Publisher: Elsevier BV
Date: 02-1993
DOI: 10.1016/0092-8674(93)90111-3
Abstract: In transgenic mice, self-reactive B lymphocytes are eliminated if they encounter membrane-bound self antigens during their development within the bone marrow. We show here that two separate and sequential events, arrested development and cell death, bring about B cell elimination. Developmental arrest is an early outcome of antigen binding in immature B cells, blocks acquisition of adhesion molecules and receptors important for B cell migration and activation, and is rapidly reversible by removal of antigen. Death of the arrested B cells occurs within 1 to 3 days and can be delayed by expression of a bcl-2 transgene, which results in escape of large numbers of self-reactive B cells from the bone marrow but fails to override the developmental arrest. These findings define a novel pathway for B cell elimination, involving an initial stage vulnerable to breakdown in autoimmune disease.
Publisher: Elsevier BV
Date: 05-1997
DOI: 10.1016/S1074-7613(00)80339-8
Abstract: Extramedullary disease (EMD) is an aggressive form of multiple myeloma (MM). Confirming the presence of plasma cells outside the bone marrow makes the diagnosis of EMD. There is no clear consensus on the management of EMD in MM, and this entity continues to remain an unmet need. Rapidly controlling EMD to prevent end-organ damage is a priority. Retrospectively, we reviewed our database for patients with EMD that received treatment with bortezomib, dexamethasone, cisplatin, doxorubicin, cyclophosphamide, etoposide (VDPACE) plus an immune modulator (IMiD) regimen. We identified 21 patients with a median age of 61 years. Ten patients received a VDPACE based regimen as a bridge to autologus stem cell transplant (ASCT). After a median follow-up of 51.4 months, the median overall survival (OS) and progression-free survival were 14.9 months (95% CI: 7.8-NA) and 5.5 months (95% CI: 3.9-NA), respectively. The overall response rate was 76%, with a manageable safety profile. Interestingly, these results were similar regardless of the presence of high-risk cytogenetics. The safety profile was acceptable. In conclusion, a salvage VDPACE-based regimen plus an IMiD remains an effective and safe bridging therapy to future ASCT and immunotherapy in relapsed/refractory multiple myeloma patients with EMD.
Publisher: Wiley
Date: 27-02-2018
DOI: 10.1111/IMM.12904
Publisher: Elsevier BV
Date: 11-1995
Publisher: Springer Science and Business Media LLC
Date: 09-12-2015
DOI: 10.1038/NATURE16165
Abstract: Inactivation of the TNFAIP3 gene, encoding the A20 protein, is associated with critical inflammatory diseases including multiple sclerosis, rheumatoid arthritis and Crohn's disease. However, the role of A20 in attenuating inflammatory signalling is unclear owing to paradoxical in vitro and in vivo findings. Here we utilize genetically engineered mice bearing mutations in the A20 ovarian tumour (OTU)-type deubiquitinase domain or in the zinc finger-4 (ZnF4) ubiquitin-binding motif to investigate these discrepancies. We find that phosphorylation of A20 promotes cleavage of Lys63-linked polyubiquitin chains by the OTU domain and enhances ZnF4-mediated substrate ubiquitination. Additionally, levels of linear ubiquitination dictate whether A20-deficient cells die in response to tumour necrosis factor. Mechanistically, linear ubiquitin chains preserve the architecture of the TNFR1 signalling complex by blocking A20-mediated disassembly of Lys63-linked polyubiquitin scaffolds. Collectively, our studies reveal molecular mechanisms whereby A20 deubiquitinase activity and ubiquitin binding, linear ubiquitination, and cellular kinases cooperate to regulate inflammation and cell death.
Publisher: Elsevier BV
Date: 10-1996
DOI: 10.1016/S0092-8674(00)81349-5
Abstract: Signals from CD4+ T cells induce two opposite fates in B cells: clonal proliferation of B cells that bind specifically to foreign antigens and clonal deletion of equivalent B cells that bind self-antigens. This B cell fate decision is determined by the concerted action of two surface proteins on activated T cells, CD40-and Fas-ligands (CD40L and FasL), whose effects are switched by signals from the B cell antigen receptor (BCR). Foreign antigens that stimulate the BCR acutely cause CD40L and FasL to promote clonal proliferation. CD40L and FasL trigger deletion, however, when the BCRs become desensitized by chronic stimulation with self-antigens or when BCRs have not bound an antigen. The need for both Fas and CD40L to correctly regulate self-reactive B cell fate may explain the severe autoantibody disorders in Fas- or CD40L-deficient children.
Publisher: Proceedings of the National Academy of Sciences
Date: 12-05-2014
Abstract: Antibodies are selected to bind microbial but not self-antigens, because binding to self would compete with binding microbes, shorten antibody half-life, and cause autoimmunity. Self-tolerance is actively acquired in part by discarding self-binding antibodies before the body is exposed to a microbe or vaccine. The experiments here provide evidence of an opposite mechanism, allowing antibodies that initially bind both foreign and self-antigens to acquire self/non-self discrimination during the course of an immune response through somatic hypermutation away from self-reactivity. In addition to selection for lower-affinity binding to self, antibody variants were selected with fewer binding sites available to bind self-antigen because most were occupied by N-linked carbohydrate, possibly explaining the frequent occurrence of N-linked glycosylation of antibody variable domains.
Publisher: Wiley
Date: 11-03-2014
DOI: 10.1111/IMM.12220
Publisher: Wiley
Date: 31-01-2021
DOI: 10.1111/IMCB.12433
Publisher: Oxford University Press (OUP)
Date: 06-2002
Abstract: Genes outside the MHC create a general susceptibility to autoimmunity in non-obese diabetic (NOD) mice. Here we describe marked differences in dendritic cell generation in vivo, caused by non-MHC NOD genes. Analyses of splenic dendritic cells from the autoimmunity-prone NOD.H-2(k) mice revealed a relative over-representation of the CD8 alpha(-) subsets, in contrast to the level of these subsets observed in the autoimmunity-resistant B10.H-2(k) congenic strain or other H-2(k) strains. The imbalance towards CD8 alpha(-) dendritic cells was selectively manifested by NOD.H-2(k)-derived cells in radiation chimeras reconstituted with equal mixtures of NOD.H-2(k) and B10.H-2(k) bone marrow cells. In addition to the cell-intrinsic imbalance in dendritic cell subsets, the myeloid lineage overall was intrinsically altered by NOD genes, as this lineage was disproportionately derived from the NOD.H-2(k) donor in mixed chimeras. These results identify a striking effect of non-MHC NOD genes upon the balance of dendritic cell subsets that may contribute to the generalized defects in self-tolerance in the NOD strain.
Publisher: The American Association of Immunologists
Date: 04-2021
Abstract: IKZF1 (IKAROS) is essential for normal lymphopoiesis in both humans and mice. Previous Ikzf1 mouse models have demonstrated the dual role for IKZF1 in both B and T cell development and have indicated differential requirements of each zinc finger. Furthermore, mutations in IKZF1 are known to cause common variable immunodeficiency in patients characterized by a loss of B cells and reduced Ab production. Through N-ethyl-N-nitrosourea mutagenesis, we have discovered a novel Ikzf1 mutant mouse with a missense mutation (L132P) in zinc finger 1 (ZF1) located in the DNA binding domain. Unlike other previously reported murine Ikzf1 mutations, this L132P point mutation (Ikzf1L132P) conserves overall protein expression and has a B cell–specific phenotype with no effect on T cell development, indicating that ZF1 is not required for T cells. Mice have reduced Ab responses to immunization and show a progressive loss of serum Igs compared with wild-type littermates. IKZF1L132P overexpressed in NIH3T3 or HEK293T cells failed to localize to pericentromeric heterochromatin and bind target DNA sequences. Coexpression of wild-type and mutant IKZF1, however, allows for localization to pericentromeric heterochromatin and binding to DNA indicating a haploinsufficient mechanism of action for IKZF1L132P. Furthermore, Ikzf1+/L132P mice have late onset defective Ig production, similar to what is observed in common variable immunodeficiency patients. RNA sequencing revealed a total loss of Hsf1 expression in follicular B cells, suggesting a possible functional link for the humoral immune response defects observed in Ikzf1L132P/L132P mice.
Publisher: Wiley
Date: 12-2005
Abstract: B cell fate is determined by the strength of signals from the antigen receptor and from co-receptors that adjust the activation threshold and tune the B cell to its environment. These co-receptors have been broadly classified into inhibitory and enhancing groups, yet some, such as CD22, may have dual effects. CD22 recruits a variety of signal enhancers at the same time as Lyn-dependent phosphorylation leads to the binding of the inhibitory phosphatase SHP-1. To assess the relative importance of Lyn- and CD22-dependent and -independent pathways, we generated Lyn and CD22 single-deficient mice and Lyn/CD22 double-deficient mice expressing the MD4 immunoglobulin transgene against hen egg lysozyme (IgHEL). This genetic approach has enabled us to compare the contributions of Lyn and CD22 to B cell development in vivo, independent of BCR specificity and in the presence and absence of self-antigen. Our results show that although the effects of Lyn are dominant in negative regulation of B cell hyperactivity, Lyn and CD22 have independent and additive effects on B cell survival. These findings emphasize the subtle nature of regulation at the BCR and the usefulness of genetic complementation to dissect common and parallel pathways.
Publisher: Proceedings of the National Academy of Sciences
Date: 10-03-2014
Abstract: Mammalian B lymphocytes make antibodies of five different heavy chain isotypes, IgM, IgD, IgG, IgE, and IgA. The different isotypes are produced at discrete stages in B-cell development from a single immunoglobulin heavy chain ( Igh ) gene, either by irreversible rearrangement of the gene to make IgG, IgE, or IgA or by alternative splicing of the RNA transcribed from the Igh gene to coexpress IgM and IgD. Developmentally regulated trans-acting factors have been hypothesized to control IgM and IgD expression from large Igh RNAs, but these factors have remained elusive for several decades. Here, using a genome-wide mutation screen in mice, we identify an obscure gene, Zfp318 , as encoding a specific and essential factor promoting IgD expression in mature B cells.
Publisher: Proceedings of the National Academy of Sciences
Date: 02-04-1996
Abstract: The mechanism by which tolerance is induced via systemic administration of high doses of aqueous antigen has been analyzed by using mice transgenic for a T-cell receptor specific for the influenza virus hemagglutinin (HA) peptide comprising amino acids 126-138. After intravenous injection of 750 (but not 75) micrograms of HA peptide, a state of hyporesponsiveness was rapidly induced. In the thymus, in situ apoptosis in the cortex and at the corticomedullary junction was responsible for a synchronous and massive deletion of CD4+ CD8+ thymocytes. In secondary lymphoid organs, HA-reactive T cells were initially activated but were hyporesponsive at the single cell level. After 3 days, however, those cells were rapidly deleted, at least partially, through an apoptotic process. Therefore, both thymic and peripheral apoptosis, in addition to T-cell receptor desensitization, contribute to high-dose tolerance.
Publisher: Wiley
Date: 12-2002
DOI: 10.1111/J.1749-6632.2002.TB05939.X
Abstract: DNA microarray analysis of B cell subsets has identified comprehensive programs of gene expression that distinguish B cells at discrete stages of differentiation. The next task is to identify key genetic signals within these complex programs that regulate the dynamic cellular events during B cell activation in vivo. After stimulation with antigen, naïve B cells proliferate and differentiate, and then produce antibodies. Crucial qualitative differences in antibody responses are observed depending on whether or not B cells receive T cell help during activation. Proteins, lipopolysaccharides, and polysaccharides stimulate T-dependent (TD), T-independent type 1 (TI-1), and type 2 (TI-2) antibody responses, respectively. Only TD responses generate somatically mutated antibody-forming (plasma) cells and memory B cells, which produce high affinity anamnestic responses to subsequent antigen challenge. Somatic mutation of immunoglobulin genes occurs during B cell proliferation in germinal centres (GC), which are typical in TD responses but rare in TI responses. However, we have described a model, which is exceptional because numerous large GC form in response to a model TI-2 antigen, (4-hydoxy-3-nitrophenyl) acetyl (NP)-Ficoll. Significantly, these GC undergo involution before memory B cells are generated. This model provides an opportunity to investigate the genetic signals that drive memory cell formation, and we have compared global gene expression in TI and TD GC to identify a relatively small number of genes that are differentially expressed between the two prototypic B cell responses. This model demonstrates how genome-scale technology can be adapted to investigate specific aspects of B cell biology.
Publisher: Springer Science and Business Media LLC
Date: 14-01-2002
DOI: 10.1038/NI752
Publisher: IEEE
Date: 08-2014
Publisher: Rockefeller University Press
Date: 24-12-2013
DOI: 10.1084/JEM.20121076
Abstract: Druggable proteins required for B lymphocyte survival and immune responses are an emerging source of new treatments for autoimmunity and lymphoid malignancy. In this study, we show that mice with an inactivating mutation in the intramembrane protease signal peptide peptidase–like 2A (SPPL2A) unexpectedly exhibit profound humoral immunodeficiency and lack mature B cell subsets, mirroring deficiency of the cytokine B cell–activating factor (BAFF). Accumulation of Sppl2a-deficient B cells was rescued by overexpression of the BAFF-induced survival protein B cell lymphoma 2 (BCL2) but not BAFF and was distinguished by low surface BAFF receptor and IgM and IgD B cell receptors. CD8-negative dendritic cells were also greatly decreased. SPPL2A deficiency blocked the proteolytic processing of CD74 MHC II invariant chain in both cell types, causing dramatic build-up of the p8 product of Cathepsin S and interfering with earlier steps in CD74 endosomal retention and processing. The findings illuminate an important role for the final step in the CD74–MHC II pathway and a new target for protease inhibitor treatment of B cell diseases.
Publisher: Wiley
Date: 2010
DOI: 10.1002/ART.25032
Abstract: In the sanroque mouse model of lupus, pathologic germinal centers (GCs) arise due to increased numbers of follicular helper T (Tfh) cells, resulting in high-affinity anti-double-stranded DNA antibodies that cause end-organ inflammation, such as glomerulonephritis. The purpose of this study was to examine the hypothesis that this pathway could account for a subset of patients with systemic lupus erythematosus (SLE). An expansion of Tfh cells is a causal, and therefore consistent, component of the sanroque mouse phenotype. We validated the enumeration of circulating T cells resembling Tfh cells as a biomarker of this expansion in sanroque mice, and we performed a comprehensive comparison of the surface phenotype of circulating and tonsillar Tfh cells in humans. This circulating biomarker was enumerated in SLE patients (n = 46), Sjögren's syndrome patients (n = 17), and healthy controls (n = 48) and was correlated with disease activity and end-organ involvement. In sanroque mice, circulating Tfh cells increased in proportion to their GC counterparts, making circulating Tfh cells a feasible human biomarker of this novel mechanism of breakdown in GC tolerance. In a subset of SLE patients (14 of 46), but in none of the controls, the levels of circulating Tfh cells (defined as circulating CXCR5+CD4+ cells with high expression of Tfh-associated molecules, such as inducible T cell costimulator or programmed death 1) were increased. This cellular phenotype did not vary with time, disease activity, or treatment, but it did correlate with the ersity and titers of autoantibodies and with the severity of end-organ involvement. These findings in SLE patients are consistent with the autoimmune mechanism in sanroque mice and identify Tfh effector molecules as possible therapeutic targets in a recognizable subset of patients with SLE.
Publisher: Proceedings of the National Academy of Sciences
Date: 17-02-2009
Abstract: A mouse neurological mutant, lister , was identified through a genome-wide N -ethyl- N -nitrosourea (ENU) mutagenesis screen. Homozygous lister mice exhibit profound early-onset and progressive neurological and motor dysfunction. lister encodes a RING finger protein, LISTERIN, which functions as an E3 ubiquitin ligase in vitro. Although lister is widely expressed in all tissues, motor and sensory neurons and neuronal processes in the brainstem and spinal cord are primarily affected in the mutant. Pathological signs include gliosis, dystrophic neurites, vacuolated mitochondria, and accumulation of soluble hyperphosphorylated tau. Analysis with a different lister allele generated through targeted gene trap insertion reveals LISTERIN is required for embryonic development and confirms that direct perturbation of a LISTERIN-regulated process causes neurodegeneration. The lister mouse uncovers a pathway involved in neurodegeneration and may serves as a model for understanding the molecular mechanisms underlying human neurodegenerative disorders.
Publisher: Springer Science and Business Media LLC
Date: 08-11-2007
DOI: 10.1038/NATURE06253
Abstract: Immune responses are normally targeted against microbial pathogens and not self-antigens by mechanisms that are only partly understood. Here we define a newly discovered pathway that prevents autoimmunity by limiting the levels on T lymphocytes of aco-stimulatory receptor, the inducible T-cell co-stimulator(ICOS). In sanroque mice homozygous for an M199R mutation in the ROQ domain of Roquin (also known as Rc3h1), increased Icos expression on T cells causes the accumulation of lymphocytes that is associated with a lupus-like autoimmune syndrome. Roquin normally limits Icos expression by promoting the degradation of Icos messenger RNA.A conserved segment in the unusually long ICOS 3' untranslated mRNA is essential for regulation by Roquin. This segment comprises a 47-base-pair minimal region complementary to T-cell-expressed microRNAs including miR-101, the repressive activity of which is disrupted by base-pair inversions predicted to abrogate miR-101 binding. These findings illuminate a critical post-transcriptional pathway within T cells that regulates lymphocyte accumulation and autoimmunity, and highlights the therapeutic potential of partially antagonising the ICOS pathway.
Publisher: Rockefeller University Press
Date: 27-10-2020
DOI: 10.1084/JEM.20200476
Abstract: NF-κB2 100 (p100) is an inhibitor of κB (IκB) protein that is partially degraded to produce the NF-κB2 52 (p52) transcription factor. Heterozygous NFKB2 mutations cause a human syndrome of immunodeficiency and autoimmunity, but whether autoimmunity arises from insufficiency of p52 or IκB function of mutated p100 is unclear. Here, we studied mice bearing mutations in the p100 degron, a domain that harbors most of the clinically recognized mutations and is required for signal-dependent p100 degradation. Distinct mutations caused graded increases in p100-degradation resistance. Severe p100-degradation resistance, due to inheritance of one highly degradation-resistant allele or two subclinical alleles, caused thymic medullary hypoplasia and autoimmune disease, whereas the absence of p100 and p52 did not. We inferred a similar mechanism occurs in humans, as the T cell receptor repertoires of affected humans and mice contained a hydrophobic signature of increased self-reactivity. Autoimmunity in autosomal dominant NFKB2 syndrome arises largely from defects in nonhematopoietic cells caused by the IκB function of degradation-resistant p100.
Publisher: Proceedings of the National Academy of Sciences
Date: 12-08-2015
Abstract: Computational tools applied to any human genome sequence identify hundreds of genetic variants predicted to disrupt the function of in idual proteins as the result of a single codon change. These tools have been trained on disease mutations and common polymorphisms but have yet to be tested against an unbiased spectrum of random mutations arising de novo. Here we perform such a test comparing the predicted and actual effects of de novo mutations in 23 genes with essential functions for normal immunity and all possible mutations in the TP53 tumor suppressor gene. These results highlight an important gap in our ability to relate genotype to phenotype in clinical genome sequencing: the inability to differentiate immediately clinically relevant mutations from nearly neutral mutations.
Publisher: Springer Science and Business Media LLC
Date: 17-02-2019
DOI: 10.1038/S41467-019-11049-4
Abstract: High-throughput single-cell RNA sequencing is a powerful technique but only generates short reads from one end of a cDNA template, limiting the reconstruction of highly erse sequences such as antigen receptors. To overcome this limitation, we combined targeted capture and long-read sequencing of T-cell-receptor (TCR) and B-cell-receptor (BCR) mRNA transcripts with short-read transcriptome profiling of barcoded single-cell libraries generated by droplet-based partitioning. We show that Repertoire and Gene Expression by Sequencing (RAGE-Seq) can generate accurate full-length antigen receptor sequences at nucleotide resolution, infer B-cell clonal evolution and identify alternatively spliced BCR transcripts. We apply RAGE-Seq to 7138 cells s led from the primary tumor and draining lymph node of a breast cancer patient to track transcriptome profiles of expanded lymphocyte clones across tissues. Our results demonstrate that RAGE-Seq is a powerful method for tracking the clonal evolution from large numbers of lymphocytes applicable to the study of immunity, autoimmunity and cancer.
Publisher: Rockefeller University Press
Date: 06-10-2009
DOI: 10.1084/JEM.20090525
Abstract: During a screen for ethylnitrosourea-induced mutations in mice affecting blood natural killer (NK) cells, we identified a strain, designated Duane, in which NK cells were reduced in blood and spleen but increased in lymph nodes (LNs) and bone marrow (BM). The accumulation of NK cells in LNs reflected a decreased ability to exit into lymph. This strain carries a point mutation within Tbx21 (T-bet), which generates a defective protein. Duane NK cells have a 30-fold deficiency in sphingosine-1-phosphate receptor 5 (S1P5) transcript levels, and S1P5-deficient mice exhibit an egress defect similar to Duane. Chromatin immunoprecipitation confirms binding of T-bet to the S1pr5 locus. S1P-deficient mice exhibit a more severe NK cell egress block, and the FTY720-sensitive S1P1 also plays a role in NK cell egress from LNs. S1P5 is not inhibited by CD69, a property that may facilitate trafficking of activated NK cells to effector sites. Finally, the accumulation of NK cells within BM of S1P-deficient mice was associated with reduced numbers in BM sinusoids, suggesting a role for S1P in BM egress. In summary, these findings identify S1P5 as a T-bet–induced gene that is required for NK cell egress from LNs and BM.
Publisher: Elsevier BV
Date: 12-1995
DOI: 10.1016/0952-7915(95)80052-2
Abstract: Self-reactive B cells are eliminated in a series of checkpoints that are triggered by antigen binding. Recent reports have shown that in addition to the processes of elimination at the immature B-cell stage, B-cell anergy and regulation of T-cell help, self-reactive cells are also controlled by follicular competition, Fas-mediated elimination by T cells and censoring in the germinal centres. Each checkpoint operates at a threshold that reflects the need to maintain immune ersity at the same time as suppressing autoimmune disease. Analysis of the motheaten mutation has given a direct demonstration of how such thresholds can be modulated by genetic effects.
Publisher: Wiley
Date: 13-07-2022
DOI: 10.1111/IMCB.12566
Abstract: Special AT‐binding protein 1 (SATB1) is a chromatin‐binding protein that has been shown to be a key regulator of T‐cell development and CD4 + T‐cell fate decisions and function. The underlying function for SATB1 in peripheral CD8 + T‐cell differentiation processes is largely unknown. To address this, we examined SATB1‐binding patterns in naïve and effector CD8 + T cells demonstrating that SATB1 binds to noncoding regulatory elements linked to T‐cell lineage–specific gene programs, particularly in naïve CD8 + T cells. We then assessed SATB1 function using N ‐ethyl‐ N ‐nitrosourea‐mutant mice that exhibit a point mutation in the SATB1 DNA‐binding domain (termed Satb1 m1Anu/m1Anu ). Satb1 m1Anu/m1Anu mice exhibit diminished SATB1‐binding, naïve, Satb1 m1Anu/m1Anu CD8 + T cells exhibiting transcriptional and phenotypic characteristics reminiscent of effector T cells. Upon activation, the transcriptional signatures of Satb1 m1Anu/m1Anu and wild‐type effector CD8 + T cells converged. While there were no overt differences, primary respiratory infection of Satb1 m1Anu/m1Anu mice with influenza A virus (IAV) resulted in a decreased proportion and number of IAV‐specific CD8 + effector T cells recruited to the infected lung when compared with wild‐type mice. Together, these data suggest that SATB1 has a major role in an appropriate transcriptional state within naïve CD8 + T cells and ensures appropriate CD8 + T‐cell effector gene expression upon activation.
Publisher: Oxford University Press (OUP)
Date: 1994
Abstract: Regulation of B lymphocyte development by the mu-membrane (mu m) and delta-membrane (delta m) heavy chains of Ig was examined in an Ig transgenic mouse model. Mice were bred on a common C57BL/6 (B6) background, and expressed rearranged and hypermutated heavy and light chain transgenes encoding high-affinity receptors for the foreign antigen hen egg lysozyme (HEL). At no stage were they exposed to HEL. Variation of the Ig heavy chain construct yielded four different types of Ig transgenic mice in which developing B lineage cells either expressed mu m and delta m in the normal physiological sequence (mu m then mu m + delta m), or produced mu m alone, delta m alone or mu m + delta m from the onset of heavy chain expression in the bone marrow. Immature B220low, HSAhigh and mature B220high, HSAlow B cells were produced in all mice regardless of their developmental pattern of mu m and delta m expression. However, production of immature B cells was most efficient when mu m heavy chain was expressed alone during early B cell development. Thus expression of delta m during this period either in the presence or absence of mu m resulted in a 2- to 3-fold reduction in the numbers of immature B cells in the spleen as well as altered levels of surface B220 and HSA on these cells in spleen and bone marrow respectively. By contrast, normal maturationally regulated expression of delta m led to the presence of increased numbers of mature B cells in the spleen and lengthened the average lifespan of these cells as determined by in vivo incorporation of 5-bromo-2'-deoxyuridine. These results pointed to selective effects of mu m and delta m heavy chains on regulation of the early and late stages of B cell development respectively, and provided a rational basis for co-expression of mu m and delta m as well as the delayed expression of delta m during normal B cell development.
Publisher: Elsevier BV
Date: 03-2013
Abstract: The recent development of human exome sequencing technology has revealed that our immune system is riddled with more genetic defects than anyone imagined. As a legacy of the recent human population explosion, we each inherit hundreds of rare mutations that alter the sequence of proteins. This mutation load is ten times higher than that induced by experimental treatment of mice by ethylnitrosourea a high fraction of which has substantial effects on immune function. This mutation burden is likely to be a major factor in the incidence of many human immune disorders, but understanding this at the level of in idual patients will require new bioinformatics and experimental strategies to assess the impact of in idual and combined mutations on immune response pathways.
Publisher: Elsevier BV
Date: 06-2003
DOI: 10.1016/S1074-7613(03)00141-9
Abstract: In a genome-wide ENU mouse mutagenesis screen a recessive mouse mutation, unmodulated, was isolated with profound defects in humoral immune responses, selective deficits in B cell activation by antigen receptors and T cell costimulation by CD28, and gradual development of atopic dermatitis with hyper-IgE. Mutant B cells are specifically defective in forming connections between antigen receptors and two key signaling pathways for immunogenic responses, NF-kappaB and JNK, but signal normally to calcium, NFAT, and ERK. The mutation alters a conserved leucine in the coiled-coil domain of CARMA-1/CARD11, a member of the MAGUK protein family implicated in organizing multimolecular signaling complexes. These results define Carma-1 as a key regulator of the plasticity in antigen receptor signaling that underpins opposing mechanisms of immunity and tolerance.
Publisher: Wiley
Date: 25-07-2017
DOI: 10.1038/ICB.2017.50
Publisher: Wiley
Date: 11-2003
Abstract: The final common pathway in diabetes development is beta cell apoptosis. We herein describe a novel diabetes model based on transgenic NOD.k iHEL mice, wherein male mice develop diabetes due to nonimmune-mediated beta cell death. Histology and electron microscopy confirm endoplasmic reticulum (ER) abnormalities that are consistent with endoplasmic stress caused by the HEL transgene. The NOD.k iHEL model may be particularly useful for studying mechanisms of beta cell death secondary to ER stress and also for testing potential therapies designed to protect beta cells from stress-induced apoptosis. The observation that only male NOD.k iHEL mice develop diabetes and exhibit ER abnormalities is intriguing and suggests these mice may be useful in deciphering the link between hyperandrogenism, insulin resistance, and diabetes.
Publisher: Research Square Platform LLC
Date: 28-08-2020
DOI: 10.21203/RS.3.RS-62714/V1
Abstract: Plasma membrane rupture (PMR) is the final cataclysmic event in lytic cell death. PMR releases intracellular molecules termed damage-associated molecular patterns (DAMPs) that propagate the inflammatory response. The underlying mechanism for PMR, however, is unknown. Here we show that the ill-characterized nerve injury-induced protein 1 (NINJ1) — a cell surface protein with two transmembrane regions — plays an essential role in the induction of PMR. A forward-genetic screen of randomly mutagenized mice linked NINJ1 to PMR. Ninj1–/– macrophages exhibited impaired PMR in response to erse inducers of pyroptotic, necrotic and apoptotic cell death, and failed to release numerous intracellular proteins including High Mobility Group Box 1 (HMGB1, a known DAMP) and Lactate Dehydrogenase (LDH, a standard measure of PMR). Ninj1–/– macrophages died, but with a distinctive and persistent ballooned morphology, attributable to defective disintegration of bubble-like herniations. Ninj1–/– mice were more susceptible than wild-type mice to Citrobacter rodentium, suggesting a role for PMR in anti-bacterial host defense. Mechanistically, NINJ1 utilized an evolutionarily conserved extracellular α-helical domain for oligomerization and subsequent PMR. The discovery of NINJ1 as a mediator of PMR overturns the long-held dogma that cell death-related PMR is a passive event. Pyroptosis is a potent inflammatory mode of lytic cell death triggered by erse infectious and sterile insults1-3. It is driven by the pore-forming fragment of gasdermin D (GSDMD)4-7 and releases two exemplar proteins: interleukin-1β (IL-1β), a pro-inflammatory cytokine, and LDH, a standard marker of PMR and lytic cell death. An early landmark study8 predicted two sequential steps for pyroptosis: (1) initial formation of a small plasma membrane pore causing IL-1β release and non-selective ionic fluxes, and (2) subsequent PMR attributable to oncotic cell swelling. PMR releases LDH (140 kDa) and large DAMPs. While the predicted size of gasdermin pores (~18 nm inner diameter9) is large enough to release IL-1β (17 kDa, ~4.5 nm diameter), the underlying mechanism for subsequent PMR has been considered a passive osmotic lysis event.
Publisher: Rockefeller University Press
Date: 15-12-1997
Abstract: Graves' Disease results from the production of autoantibodies against receptors for thyroid stimulating hormone (TSH) on thyroid epithelial cells, and represents the prototype for numerous autoimmune diseases caused by autoantibodies that bind to organ-specific cell membrane antigens. To study how humoral tolerance is normally maintained to organ-specific membrane antigens, transgenic mice were generated selectively expressing membrane-bound hen egg lysozyme (mHEL) on the thyroid epithelium. In contrast to the deletion of autoreactive B cells triggered by systemic mHEL (Hartley, S.B., J. Crosbie, R. Brink, A.B. Kantor, A. Basten, and C.C. Goodnow. 1991. Nature. 353:765–769), selective expression of mHEL autoantigen on thyroid cells did not trigger elimination or inactivation of circulating HEL-reactive B cells. These results provide evidence that tolerance is not actively acquired to organ-specific antigens in the preimmune B cell repertoire, underscoring the importance of maintaining tolerance to such antigens by other mechanisms. The role of an intact endothelial barrier in sequestering organ-specific antigens from circulating preimmune B cells is discussed.
Publisher: Proceedings of the National Academy of Sciences
Date: 24-07-2007
Abstract: Condensins are ubiquitously expressed multiprotein complexes that are important for chromosome condensation and epigenetic regulation of gene transcription, but whose specific roles in vertebrates are poorly understood. We describe a mouse strain, nessy, isolated during an ethylnitrosourea screen for recessive immunological mutations. The nessy mouse has a defect in T lymphocyte development that decreases circulating T cell numbers, increases their expression of the activation/memory marker CD44, and dramatically decreases the numbers of CD4 + CD8 + thymocytes and their immediate DN4 precursors. A missense mutation in an unusual alternatively spliced first exon of the kleisin β gene, a member of the condensin II complex, was shown to be responsible and act in a T cell-autonomous manner. Despite the ubiquitous expression and role of condensins, kleisin β nes/nes mice were viable, fertile, and showed no defects even in the parallel pathway of B cell lymphocyte differentiation. These data define a unique lineage-specific requirement for kleisin β in mammalian T cell differentiation.
Publisher: Springer Science and Business Media LLC
Date: 10-02-2000
DOI: 10.1038/35001102
Abstract: Therapy for transplant rejection, autoimmune disease and allergy must target mature lymphocytes that have escaped censoring during their development. FK506 and cyclosporin are immunosuppressants which block three antigen-receptor signalling pathways (NFAT, NFkappaB and JNK), through inhibition of calcineurin, and inhibit mature lymphocyte proliferation to antigen. Neither drug induces long-lived tolerance in vivo, however, necessitating chronic use with adverse side effects. Physiological mechanisms of peripheral tolerance to self-antigens provide an opportunity to emulate these processes pharmacologically. Here we use gene-expression arrays to provide a molecular explanation for the loss of mitogenic response in peripheral B-cell anergy, one aspect of immunological tolerance. Self-antigen induces a set of genes that includes negative regulators of signalling and transcription but not genes that promote proliferation. FK506 interferes with calcium-dependent components of the tolerance response and blocks an unexpectedly small fraction of the activation response. Many genes that were not previously connected to self-tolerance are revealed, and our findings provide a molecular fingerprint for the development of improved immunosuppressants that prevent lymphocyte activation without blocking peripheral tolerance.
Publisher: Elsevier BV
Date: 1990
Publisher: Elsevier BV
Date: 12-1992
DOI: 10.1016/0952-7915(92)90049-K
Abstract: Discrimination between self and non-self in humoral immunity is mediated in part by elimination or inactivation of self-reactive B-cell clones. This type of repertoire censoring requires that self-reactive B cells make a choice between these and alternative cellular fates. The details of this developmental decision-making and the steps where it is prone to go awry in autoimmunity have yet to be untangled, but genetic analysis appears likely to lead the way.
Publisher: Public Library of Science (PLoS)
Date: 25-07-2013
Publisher: Elsevier BV
Date: 06-2001
DOI: 10.1016/S0140-6736(00)05185-0
Abstract: Antigen delivers both immunogenic and tolerogenic signals to lymphocytes. The outcome of antigen exposure represents a complex integration of the timing of antigen binding with signals from many other immunogenic and tolerogenic costimulatory pathways. A road map of these signalling pathways is only beginning to be charted, revealing the mechansim of action and limitations of current immunotherapeutic agents and the points of attack for new agents. Ciclosporin and tacrolimus interfere with tolerogenic signals from antigen in addition to blocking immunogenic signals, thus preventing active establishment of tolerance. Corticosteroids inhibit a key immunogenic pathway, NFkappaB, and more specific inhibitors of this pathway may allow tolerance to be actively established while immune responses are blocked. New experimental therapies aim to mimic tolerogenic antigen signals by chronically stimulating antigen receptors with antigen or antibodies to the receptor, or aim to block costimulatory pathways involving CD40 ligand, B7, or interleukin 2. Obtaining the desired response with these strategies is unpredictable because many of these signals have both tolerogenic and immunogenic roles. The cause of autoimune diseases has been determined for several rare monogenic disorders, revealing inherited deficiencies in tolerogenic costimulatory pathways such as FAS. Common autoimmune disorders may have a biochemically related pathogenesis.
Publisher: Proceedings of the National Academy of Sciences
Date: 08-07-2022
Abstract: Humans lack the capacity to produce the Galα1–3Galβ1–4GlcNAc (α-gal) glycan, and produce anti-α-gal antibodies upon exposure to the carbohydrate on a erse set of immunogens, including commensal gut bacteria, malaria parasites, cetuximab, and tick proteins. Here we use X-ray crystallographic analysis of antibodies from α-gal knockout mice and humans in complex with the glycan to reveal a common binding motif, centered on a germline-encoded tryptophan residue at Kabat position 33 (W33) of the complementarity-determining region of the variable heavy chain (CDRH1). Immunoglobulin sequencing of anti-α-gal B cells in healthy humans and tick-induced mammalian meat anaphylaxis patients revealed preferential use of heavy chain germline IGHV3-7, encoding W33, among an otherwise highly polyclonal antibody response. Antigen binding was critically dependent on the presence of the germline-encoded W33 residue for all of the analyzed antibodies moreover, introduction of the W33 motif into naive IGHV3-23 antibody phage libraries enabled the rapid selection of α-gal binders. Our results outline structural and genetic factors that shape the human anti-α-galactosyl antibody response, and provide a framework for future therapeutics development.
Publisher: The American Association of Immunologists
Date: 12-2012
Abstract: CD1d-dependent NKT cells represent a heterogeneous family of effector T cells including CD4+CD8− and CD4−CD8− subsets that respond to glycolipid Ags with rapid and potent cytokine production. NKT cell development is regulated by a unique combination of factors, however very little is known about factors that control the development of NKT subsets. In this study, we analyze a novel mouse strain (helpless) with a mis-sense mutation in the BTB-POZ domain of ZBTB7B and demonstrate that this mutation has dramatic, intrinsic effects on development of NKT cell subsets. Although NKT cell numbers are similar in Zbtb7b mutant mice, these cells are hyperproliferative and most lack CD4 and instead express CD8. Moreover, the majority of ZBTB7B mutant NKT cells in the thymus are retinoic acid–related orphan receptor γt positive, and a high frequency produce IL-17 while very few produce IFN-γ or other cytokines, sharply contrasting the profile of normal NKT cells. Mice heterozygous for the helpless mutation also have reduced numbers of CD4+ NKT cells and increased production of IL-17 without an increase in CD8+ cells, suggesting that ZBTB7B acts at multiple stages of NKT cell development. These results reveal ZBTB7B as a critical factor genetically predetermining the balance of effector subsets within the NKT cell population.
Publisher: The Royal Society
Date: 05-2012
DOI: 10.1098/RSOB.120061
Abstract: Accurate identification of sparse heterozygous single-nucleotide variants (SNVs) is a critical challenge for identifying the causative mutations in mouse genetic screens, human genetic diseases and cancer. When seeking to identify causal DNA variants that occur at such low rates, they are overwhelmed by false-positive calls that arise from a range of technical and biological sources. We describe a strategy using whole-exome capture, massively parallel DNA sequencing and computational analysis, which identifies with a low false-positive rate the majority of heterozygous and homozygous SNVs arising de novo with a frequency of one nucleotide substitution per megabase in progeny of N -ethyl- N -nitrosourea (ENU)-mutated C57BL/6j mice. We found that by applying a strategy of filtering raw SNV calls against known and platform-specific variants we could call true SNVs with a false-positive rate of 19.4 per cent and an estimated false-negative rate of 21.3 per cent. These error rates are small enough to enable calling a causative mutation from both homozygous and heterozygous candidate mutation lists with little or no further experimental validation. The efficacy of this approach is demonstrated by identifying the causative mutation in the Ptprc gene in a lymphocyte-deficient strain and in 11 other strains with immune disorders or obesity, without the need for meiotic mapping. Exome sequencing of first-generation mutant mice revealed hundreds of unphenotyped protein-changing mutations, 52 per cent of which are predicted to be deleterious, which now become available for breeding and experimental analysis. We show that exome sequencing data alone are sufficient to identify induced mutations. This approach transforms genetic screens in mice, establishes a general strategy for analysing rare DNA variants and opens up a large new source for experimental models of human disease.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 15-06-1990
Abstract: The immune system normally avoids producing antibodies that react with autologous ("self") antigens by censoring self-reactive T and B cells. Unlike the T cell repertoire, antibody ersity is generated within the B cell repertoire in two phases the first occurs by gene rearrangement in primary lymphoid organs, and the second phase involves antigen-driven hypermutation in peripheral lymphoid organs. The possibility that distinct cellular mechanisms may impose self tolerance at these two different phases of B cell ersification may explain recent findings in transgenic mouse models, in which self-reactive B cells appear to be silenced both by functional inactivation and by physical elimination.
Publisher: The American Association of Immunologists
Date: 15-03-2015
Abstract: Defining the minimal thresholds for effective antiviral T cell immunity is important for clinical decisions in immunodeficient patients. TCR signaling is critical for T cell development, activation, and effector functions. In this article, we analyzed which of these TCR-mediated processes is limiting for antiviral immunity in a mouse strain with reduced expression of SLP-76 (twp mice). Despite severe T cell activation defects in vitro, twp mice generated a normal proportion of antiviral effector T cells postinfection with lymphocytic choriomeningitis virus (LCMV). Twp CD8+ T cells showed impaired polyfunctional cytokine production, whereas cytotoxicity as the crucial antiviral effector function for LCMV control was normal. The main limiting factor in the antiviral response of twp mice was impaired T cell proliferation and survival, leading to a 5- to 10-fold reduction of antiviral T cells at the peak of the immune response. This was still sufficient to control infection with the LCMV Armstrong strain, but the more rapidly replicating LCMV-WE induced T cell exhaustion and viral persistence. Thus, under conditions of impaired TCR signaling, reduced T cell expansion was the limiting factor in antiviral immunity. These findings have implications for understanding antiviral immunity in patients with T cell deficiencies.
Publisher: Springer Science and Business Media LLC
Date: 20-07-2010
DOI: 10.1038/NI.1900
Abstract: This paper synthesizes recent progress toward understanding the integrated control systems and fail-safes that guide the quality and quantity of antibody produced by B cells. We focus on four key decisions: (1) the choice between proliferation or death in perifollicular B cells in the first 3 days after antigen encounter (2) differentiation of proliferating perifollicular B cells into extrafollicular plasma cells or germinal center B cells (3) positive selection of B cell antigen receptor (BCR) affinity for foreign antigen versus negative selection of BCR affinity for self antigen in germinal center B cells and (4) survival versus death of antibody-secreting plasma cells. Understanding the engineering of these control systems represents a challenging future step for treating disorders of antibody production in autoimmunity, allergy and immunodeficiency.
Publisher: The American Association of Immunologists
Date: 15-03-2015
Abstract: Gene variants that disrupt TCR signaling can cause severe immune deficiency, yet less disruptive variants are sometimes associated with immune pathology. Null mutations of the gene encoding the scaffold protein Src homology 2 domain–containing leukocyte protein of 76 kDa (SLP-76), for ex le, cause an arrest of T cell positive selection, whereas a synthetic membrane-targeted allele allows limited positive selection but is associated with proinflammatory cytokine production and autoantibodies. Whether these and other enigmatic outcomes are due to a biochemical uncoupling of tolerogenic signaling, or simply a quantitative reduction of protein activity, remains to be determined. In this study we describe a splice variant of Lcp2 that reduced the amount of wild-type SLP-76 protein by ∼90%, disrupting immunogenic and tolerogenic pathways to different degrees. Mutant mice produced excessive amounts of proinflammatory cytokines, autoantibodies, and IgE, revealing that simple quantitative reductions of SLP-76 were sufficient to trigger immune dysregulation. This allele reveals a dose-sensitive threshold for SLP-76 in the balance of immunity and immune dysregulation, a common disturbance of atypical clinical immune deficiencies.
Publisher: Rockefeller University Press
Date: 10-1992
Abstract: A series of immunoglobulin (Ig)-transgenic mice were generated to study the functional capabilities of the IgM and IgD classes of B lymphocyte antigen receptor in regulating both cellular development and responses to specific antigen. B cells from Ig-transgenic mice expressing either hen-egg lysozyme (HEL)-specific IgM or IgD alone were compared with B cells from mice that coexpressed IgM and IgD of the same anti-HEL specificity. In all three types of Ig-transgenic mice, conventional B cells specific for HEL exhibited exclusion of endogenous Ig expression and matured to populate the usual microenvironments in peripheral lymphoid tissues. These peripheral B cells could be stimulated by HEL through either IgM or IgD antigen receptors to generate T cell dependent antibody production in vivo or to enhance T cell independent proliferative responses to lipopolysaccharide in vitro. Conversely, when HEL was encountered in vivo as a self-antigen, B cells expressing HEL-specific IgM or IgD alone were both rendered tolerant. In each case this occurred by clonal anergy in response to soluble autologous HEL, and clonal deletion when HEL was recognized as a membrane-bound self-antigen. Taken together, these findings indicate that IgM and IgD antigen receptors expressed alone on conventional B cells can support normal differentiation, antigen-dependent activation, and induction of self-tolerance, the only overt difference lying in a greater degree of receptor downregulation for IgM relative to IgD after induction of clonal anergy by soluble HEL.
Publisher: Elsevier BV
Date: 04-1997
DOI: 10.1016/S0960-9822(06)00105-9
Abstract: The recent discovery of a receptor needed for lymphocyte migration into lymphoid follicles indicates that multiple chemoattractive gradients allow lymphocytes to navigate to specialized niches in lymphoid organs.
Publisher: Annual Reviews
Date: 04-1998
DOI: 10.1146/ANNUREV.IMMUNOL.16.1.645
Abstract: ▪ Abstract Antigen receptors on lymphocytes play a central role in immune regulation by transmitting signals that positively or negatively regulate lymphocyte survival, migration, growth, and differentiation. This review focuses on how opposing positive or negative cellular responses are brought about by antigen receptor signaling. Four types of extracellular inputs shape the response to antigen: (a) the concentration of antigen (b) the avidity with which antigen is bound (c) the timing and duration of antigen encounter and (d) the association of antigen with costimuli from pathogens, the innate immune system, or other lymphocytes. Intracellular signaling by antigen receptors is not an all-or-none event, and these external variables alter both the quantity and quality of signaling. Recent findings in B lymphocytes have clearly illustrated that these external inputs affect the magnitude and duration of the intracellular calcium response, which in turn contributes to differential triggering of the transcriptional regulators NFκB, JNK, NFAT, and ERK. The regulation of calcium responses involves a network of tyrosine kinases (e.g. lyn, syk), tyrosine or lipid phosphatases (CD45, SHP-1, SHIP), and accessory molecules (CD21/CD19, CD22, FcRγ2b). Understanding the biochemistry and logic behind these integrative processes will allow development of more selective and efficient pharmaceuticals that suppress, modify, or augment immune responses in autoimmunity, transplantation, allergy, vaccines, and cancer.
Publisher: Rockefeller University Press
Date: 02-1994
Abstract: The specificity of antibody (Ab) responses depends on focusing helper T (Th) lymphocyte signals to suitable B lymphocytes capable of binding foreign antigens (Ags), and away from nonspecific or self-reactive B cells. To investigate the molecular mechanisms that prevent the activation of self-reactive B lymphocytes, the activation requirements of B cells specific for the Ag hen egg lysozyme (HEL) obtained from immunoglobulin (Ig)-transgenic mice were compared with those of functionally tolerant B cells isolated from Ig-transgenic mice which also express soluble HEL. To eliminate the need for surface (s)Ig-mediated Ag uptake and presentation and allow the effects of sIg signaling to be studied in isolation, we assessed the ability of allogeneic T cells from bm12 strain mice to provide in vivo help to C57BL/6 strain-transgenic B cells. Interestingly, non-tolerant Ig-transgenic B cells required both allogeneic Th cells and binding of soluble HEL for efficient activation and Ab production. By contrast, tolerant self-reactive B cells from Ig/HEL double transgenic mice responded poorly to the same combination of allogeneic T cells and soluble HEL. The tolerant B cells were nevertheless normally responsive to stimulation with interleukin 4 and anti-CD40 Abs in vitro, suggesting that they retained the capacity to respond to mediators of T cell help. However, the tolerant B cells exhibited a proximal block in the sIg signaling pathway which prevented activation of receptor-associated tyrosine kinases in response to the binding of soluble HEL. The functional significance of this sIg signaling defect was confirmed by using a more potent membrane-bound form of HEL capable of triggering sIg signaling in tolerant B cells, which markedly restored their ability to collaborate with allogeneic Th cells and produce Ab. These findings indicate that Ag-specific B cells require two signals for mounting a T cell-dependent Ab response and identify regulation of sIg signaling as a mechanism for controlling self-reactive B cells.
Publisher: Elsevier BV
Date: 03-2001
DOI: 10.1016/S0022-1759(00)00352-5
Abstract: Here we describe a method for detecting ultralow frequency target cells from within a high background of irrelevant cells by a novel method, single epitope multiple staining (SEMS). S les of murine splenocytes were seeded with a low number of splenocytes from mice transgenic for a hen eggwhite lysozyme (HEL)-specific immunoglobulin (Ig). These s les were stained with two reagents specific for the same epitope expressed by the transgenic B cells, which had been conjugated to two different detectable labels (FITC and biotin). This dual staining of a single epitope allowed us to reduce the background due both to non-specific binding of reagents and to probabilistic distribution of the cells. We also were able to detect the cells based on knowing only one thing about them, namely, their antigen specificity. The SEMS method allowed us to reproducibly detect transgenic cells at frequencies below one cell in one million cells. SEMS could be used to increase the sensitivity of numerous fluorescence-based applications in addition to the detection and isolation of antigen-specific lymphocytes, including the detection and highly specific isolation of genetically modified cells, transformed cells, stem cells, fetal cells, or infectious organisms.
Publisher: Informa UK Limited
Date: 12-1988
Abstract: To examine the influences responsible for shaping the T-cell repertoire in vivo, we have introduced T-cell receptors of defined specificity into mice. In this report, we analyze transgenic mice carrying a T-cell receptor alpha-chain gene from a pigeon cytochrome c-reactive T-cell line. A variant of this construct, which has the immunoglobulin heavy-chain enhancer inserted into the JC intron, was also introduced into mice. Addition of the enhancer increased the steady-state level of transgene-encoded mRNA three- to fivefold in cultured T cells, leading to a two- to threefold increase in surface expression. In vivo, the difference between these two constructs was even more significant, increasing the number of transgene-positive cells from approximately 5 to 70% and the T-cell receptor surface density two- to threefold. Surprisingly, while surface expression of either type of transgene was limited to T cells, we found little tissue specificity with respect to transcription. In T cells expressing the alpha chain from the enhancer-containing construct, immunoprecipitation with a 2B4 alpha-specific monoclonal antibody revealed the expected disulfide-linked dimer. Costaining of these T cells with the 2B4 alpha-specific monoclonal antibody versus anti-CD3 indicated that expression of the transgene-encoded alpha chain precludes expression of endogenous alpha chains on the majority of cells in contrast, 2B4 alpha-chain expression from the construct lacking the enhancer is inefficient at suppressing endogenous alpha-chain expression. In mice of the enhancer lineage, Southern blot analysis indicated suppression of endogenous alpha-chain rearrangements in T-cell populations, consistent with the observed allelic exclusion at the cellular level. Interestingly, newborn, but not adult, mice of this lineage also showed an increase in retention of unrearranged delta-chain loci in thymocyte DNA, presumably resulting from the suppression of alpha-chain rearrangements. This observation indicates that at least a fraction of alpha:beta-positive T cells have never attempted to produce functional delta rearrangements, thus suggesting that alpha:beta and gamma:delta T cells may be derived from different T-cell compartments (at least during the early phases of T-cell differentiation).
Publisher: Springer Science and Business Media LLC
Date: 2014
Publisher: Rockefeller University Press
Date: 26-06-2006
DOI: 10.1084/JEM.20060552
Abstract: Divergent hypotheses exist to explain how signaling by the B cell receptor (BCR) is initiated after antigen binding and how it is qualitatively altered in anergic B cells to selectively uncouple from nuclear factor κB and c-Jun N-terminal kinase pathways while continuing to activate extracellular signal–regulated kinase and calcium–nuclear factor of activated T cell pathways. Here we find that BCRs on anergic cells are endocytosed at a very enhanced rate upon binding antigen, resulting in a large steady-state pool of intracellularly sequestered receptors that appear to be continuously cycling between surface and intracellular compartments. This endocytic mechanism is exquisitely sensitive to the lowering of plasma membrane cholesterol by methyl-β-cyclodextrin, and, when blocked in this way, the sequestered BCRs return to the cell surface and RelA nuclear accumulation is stimulated. In contrast, when plasma membrane cholesterol is lowered and GM1 sphingolipid markers of membrane rafts are depleted in naive B cells, this does not diminish BCR signaling to calcium or RelA. These results provide a possible explanation for the signaling changes in clonal anergy and indicate that a chief function of membrane cholesterol in B cells is not to initiate BCR signaling, but instead to terminate a subset of signals by rapid receptor internalization.
Publisher: Springer Science and Business Media LLC
Date: 08-02-2023
DOI: 10.1038/S41467-023-36295-5
Abstract: Emerging variants of concern (VOCs) are threatening to limit the effectiveness of SARS-CoV-2 monoclonal antibodies and vaccines currently used in clinical practice broadly neutralizing antibodies and strategies for their identification are therefore urgently required. Here we demonstrate that broadly neutralizing antibodies can be isolated from peripheral blood mononuclear cells of convalescent patients using SARS-CoV-2 receptor binding domains carrying epitope-specific mutations. This is exemplified by two human antibodies, GAR05, binding to epitope class 1, and GAR12, binding to a new epitope class 6 (located between class 3 and 5). Both antibodies broadly neutralize VOCs, exceeding the potency of the clinical monoclonal sotrovimab (S309) by orders of magnitude. They also provide prophylactic and therapeutic in vivo protection of female hACE2 mice against viral challenge. Our results indicate that exposure to SARS-CoV-2 induces antibodies that maintain broad neutralization against emerging VOCs using two unique strategies: either by targeting the ergent class 1 epitope in a manner resistant to VOCs (ACE2 mimicry, as illustrated by GAR05 and mAbs P2C-1F11/S2K14) or alternatively, by targeting rare and highly conserved epitopes, such as the new class 6 epitope identified here (as illustrated by GAR12). Our results provide guidance for next generation monoclonal antibody development and vaccine design.
Publisher: Springer Science and Business Media LLC
Date: 09-1994
DOI: 10.1038/371389A0
Abstract: Two different approaches to follow clones of B lymphocytes in a erse preimmune repertoire reveal a new process for eliminating self-reactive cells in the periphery which depends on competition between cells with different specificities. A key feature of this censoring mechanism is the selective exclusion of self-antigen-binding B cells from the normal migration route into lymphoid follicles, resulting in their premature death. This is a striking ex le of homeostasis by cellular competition for limiting niches and may explain the paradoxical association between immunodeficiency and autoimmunity.
Publisher: Elsevier BV
Date: 06-2004
Publisher: Bentham Science Publishers Ltd.
Date: 05-2006
DOI: 10.2174/156652406776894563
Abstract: It is now widely accepted that lymphomagenesis is a multistep transformation process. A number of genetic changes and environmental and infectious factors contributing to the development and malignant progression of B-cell lymphoproliferative disorders are well documented. Reciprocal chromosomal translocations involving the immunoglobulin loci are a hallmark of most mature B cell lymphomas and lead to dysregulated expression of proto-oncogenes (c-myc) important for cell proliferation or genes involved in cell cycle progression (cyclin D1), differentiation block (bcl-6, PAX5) and cell survival (bcl-2, NF-kappaB). In addition, genetic alterations that inactivate tumor suppressor genes (p53, p16) have been frequently detected in some lymphoma tissues. Many of these genes are normally regulated by signals from the B cell antigen receptor. The high prevalence of bacterial and viral infection in lymphoma patients supports the hypothesis that infectious agents may play a contributory role in the development and evolution of B cell lymphoproliferative disorders by either directly inducing polyclonal B cell hyperactivation (EBV, HCV), or providing a chronic antigenic stimulus (EBV, HCV, HBV, H. pylori), or mimicking B cell antigen receptor signaling (EBV, HCV, HHV8), although whether these are causative factors or they are secondary to genetic changes in lymphomagenesis remains to be defined. Stimulatory signals from reactive T cells, local cytokines and growth factors can also contribute, to some extent, to the progression of transformation. Modulation of B cell antigen receptor signaling therefore emerges as a potentially powerful strategy for controlling the growth of certain B cell lymphomas.
Publisher: Elsevier BV
Date: 11-2011
DOI: 10.1016/J.LEUKRES.2011.07.024
Abstract: To understand the interactions between Notch1 and Ikaros in the evolution of T cell acute lymphoblastic leukemia (T-ALL), we traced the evolution of T-ALL in mice with an inherited Ikaros mutation, Ikzf1(Plstc) which inactivates DNA binding. DNA-binding Ikaros repressed Notch1 response in transfected cell lines and in CD4(+)8(+) (DP) thymocytes from young pre-leukemic Ikzf1(Plstc) heterozygous mice. In DP thymocytes, a 50-1000 fold escalation in mRNA for Notch1 target genes Hes1 and Dtx1 preceded thymic lymphoma or leukemia and was closely correlated with the first detectable differentiation abnormalities, loss of heterozygosity (LOH) eliminating wild-type Ikzf1, and multiple missense and truncating Notch1 mutations. These findings illuminate the early stages of leukemogenesis by demonstrating progressive exaggeration of Notch1 responsiveness at the DP thymocyte stage brought about by multiple mutations acting in concert upon the Notch1 pathway.
Publisher: Elsevier BV
Date: 04-1986
DOI: 10.1016/0008-8749(86)90211-X
Abstract: Recent progress in the serology, biochemistry, and now the molecular genetics of T-cell receptor molecules has brought within reach the prospect of solving some of the most basic questions about the nature of T-cell recognition. These include the exact nature of the receptor-major histocompatibility complex (MHC)-antigen recognition event and the sequential expression of T-cell receptor molecules in the thymus.
Publisher: Elsevier BV
Date: 04-1998
Publisher: Annual Reviews
Date: 12-2005
DOI: 10.1146/ANNUREV.GENET.39.110304.095817
Abstract: The human and mouse genome sequences bring closer the goal of understanding how characteristics of adult mammalian physiology and pathology are encoded by DNA. Here we review the challenge of understanding how genes specify mammalian traits, with particular focus on the cells and behavior of the immune system. Summarized is the emerging experience, advantages, and limitations of using ethylnitrosourea (ENU) to modify the mouse genome and select informative variants by phenotypic screens, yielding two main conclusions. First, ENU-induced variation provides an eminently feasible route to understanding how the genome encodes important mammalian processes without any prior assumptions about genes, their chromosomal locations, or expression patterns. Second, ENU alleles match those arising by natural variation. By changing in idual protein domains or splice products, these alleles reveal separate gene functions specified through protein combinations.
Publisher: Rockefeller University Press
Date: 08-1995
Abstract: The normal migration route of B cells into follicular areas of spleen and lymph nodes is altered in the case of autoreactive cells that have bound self-antigen. To begin characterizing the molecular requirements for B cell migration into follicles, cells were treated with pertussis toxin (PTX), an inhibitor of signaling by many G protein-coupled chemokine receptors. Lymphocyte accumulation in the spleen is not inhibited by PTX and, therefore, the distribution of transferred cells was examined in this tissue. In contrast to untreated cells that localized predominantly in follicular areas within white pulp cords, PTX-treated B cells failed to enter white pulp areas altogether and accumulated in the splenic red pulp. T cells were also excluded from white pulp cords and in the case of both cell types, the adenosine diphosphate-ribosylating subunit of the toxin was required to block white pulp entry. These findings implicate a G protein-coupled receptor in lymphocyte migration into splenic white pulp cords. Exclusion of PTX-treated cells from all organized areas of secondary lymphoid tissues raises the possibility that the association observed between PTX treatment and predisposition to autoimmune disease results from inhibition of tolerance mechanisms that normally operate within secondary lymphoid tissues.
Publisher: Wiley
Date: 09-04-2008
DOI: 10.1111/J.1365-2141.2008.07065.X
Abstract: The human beta globin locus consists of an upstream LCR and functional genes arranged sequentially in the order of their expression during development: 5'-HBE1, HBG2, HBG1, HBD, HBB-3'. Haemoglobin switching entails the successive recruitment of these genes into an active chromatin hub (ACH). Here we show that the transcription factor Ikaros plays a major role in the formation of the beta-globin ACH, and in haemoglobin switching. In Plastic mice, where the DNA-binding region of Ikaros is disrupted by a point mutation, there is concomitant marked down-regulation of HBB, and up-regulation of HBG expression. We show for the first time Ikaros and its family member Eos, bind to critical cis elements implicated in haemoglobin switching and deletional hereditary persistence of fetal haemoglobin (HPFH). Chromatin conformation capture (3C) data demonstrated that Ikaros facilitates long-distance DNA looping between the LCR and a region upstream of HBD. This study provides new insights into the mechanism of stage-specific assembly of the beta-globin ACH, and HPFH.
Publisher: Oxford University Press (OUP)
Date: 08-03-2015
DOI: 10.1093/BIOINFORMATICS/BTV135
Abstract: Motivation: Increasingly, cost-effective high-throughput DNA sequencing technologies are being utilized to sequence human pedigrees to elucidate the genetic cause of a wide variety of human diseases. While numerous tools exist for variant prioritization within a single genome, the ability to concurrently analyze variants within pedigrees remains a challenge, especially should there be no prior indication of the underlying genetic cause of the disease. Here, we present a tool, variant analysis of sequenced pedigrees (VASP), a flexible data integration environment capable of producing a summary of pedigree variation, providing relevant information such as compound heterozygosity, genome phasing and disease inheritance patterns. Designed to aggregate data across a sequenced pedigree, VASP allows both powerful filtering and custom prioritization of both single nucleotide variants (SNVs) and small indels. Hence, clinical and research users with prior knowledge of a disease are able to dramatically reduce the variant search space based on a wide variety of custom prioritization criteria. Availability and implementation: Source code available for academic non-commercial research purposes at attmattmattmatt/VASP. Contact: matt.field@anu.edu.au Supplementary information: Supplementary data are available at Bioinformatics online.
Publisher: Proceedings of the National Academy of Sciences
Date: 31-10-2006
Abstract: An N -ethyl- N -nitrosourea mutagenesis screen in mice was performed to isolate regulators of circulating platelet number. We report here recessive thrombocytopenia and kidney disease in plt1 mice, which is the result of a severe but partial loss-of-function mutation in the gene encoding glycoprotein- N -acetylgalactosamine-3-β-galactosyltransferase (C1GalT1), an enzyme essential for the synthesis of extended mucin-type O-glycans. Platelet half-life and basic hemostatic parameters were unaffected in plt1 lt1 mice, and the thrombocytopenia and kidney disease were not attenuated on a lymphocyte-deficient rag1 -null background. gpIbα and podocalyxin were found to be major underglycosylated proteins in plt1 lt1 platelets and the kidney, respectively, implying that these are key targets for C1GalT1, appropriate glycosylation of which is essential for platelet production and kidney function. Compromised C1GalT1 activity has been associated with immune-mediated diseases in humans, most notably Tn syndrome and IgA nephropathy. The disease in plt1 lt1 mice suggests that, in addition to immune-mediated effects, intrinsic C1Gal-T1 deficiency in megakaryocytes and the kidney may contribute to pathology.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 04-07-0004
DOI: 10.1126/SCIIMMUNOL.ABQ3277
Abstract: High-level expression of the transcription factor T-bet characterizes a phenotypically distinct murine B cell population known as “age-associated B cells” (ABCs). T-bet–deficient mice have reduced ABCs and impaired humoral immunity. We describe a patient with inherited T-bet deficiency and largely normal humoral immunity including intact somatic hypermutation, affinity maturation and memory B cell formation in vivo, and B cell differentiation into Ig-producing plasmablasts in vitro. Nevertheless, the patient exhibited skewed class switching to IgG1, IgG4, and IgE, along with reduced IgG2, both in vivo and in vitro. Moreover, T-bet was required for the in vivo and in vitro development of a distinct subset of human B cells characterized by reduced expression of CD21 and the concomitantly high expression of CD19, CD20, CD11c, FCRL5, and T-bet, a phenotype that shares many features with murine ABCs. Mechanistically, human T-bet governed CD21 lo CD11c hi B cell differentiation by controlling the chromatin accessibility of lineage-defining genes in these cells: FAS , IL21R , SEC61B , DUSP4 , DAPP1 , SOX5 , CD79B , and CXCR4 . Thus, human T-bet is largely redundant for long-lived protective humoral immunity but is essential for the development of a distinct subset of human CD11c hi CD21 lo B cells.
Publisher: Proceedings of the National Academy of Sciences
Date: 08-1990
Abstract: In double-transgenic mice expressing a gene construct encoding hen egg lysozyme as well as rearranged anti-lysozyme antibody genes, large numbers of anti-lysozyme B cells are present in peripheral lymphoid tissues but are profoundly tolerant. The cellular basis for this form of non-deletional self-tolerance was explored. The tolerant anti-lysozyme B cells from double-transgenic mice were found to produce much less antibody than nontransgenic controls in T-cell-dependent antigen-specific responses, in adoptive transfer in vivo, and in hanging-drop cultures in vitro, as well as in response to stimulation with the nonspecific mitogen lipopolysaccharide. The diminished responsiveness of the tolerant B cells was not due to a reduction in the number of responding B-cell precursors per se nor were suppressor cells detected in titration, depletion, or mixing experiments. Nondeletional tolerance in this model, therefore, appears to result from an intrinsic functional change in the self-reactive B cells themselves.
Publisher: Elsevier BV
Date: 07-2007
DOI: 10.1016/J.CELL.2007.06.033
Abstract: In the immune system, many tolerance checkpoints exist to prevent self-antigens from stimulating the relentless growth of self-reactive B and T lymphocytes. The genes and molecular pathways underpinning these checkpoints overlap with those involved in tumor suppression. As with an inherited predisposition to cancer, inherited defects in self-tolerance genes typically precipitate autoimmune disease stochastically after a latent phase. Multiple mutations, inherited and somatic, may be needed before a self-reactive clone bypasses sequential tolerance checkpoints resulting in the emergence of autoimmune disease.
Publisher: eLife Sciences Publications, Ltd
Date: 23-10-2015
DOI: 10.7554/ELIFE.08698
Abstract: T follicular helper cells (Tfh) are critical for the longevity and quality of antibody-mediated protection against infection. Yet few signaling pathways have been identified to be unique solely to Tfh development. ROQUIN is a post-transcriptional repressor of T cells, acting through its ROQ domain to destabilize mRNA targets important for Th1, Th17, and Tfh biology. Here, we report that ROQUIN has a paradoxical function on Tfh differentiation mediated by its RING domain: mice with a T cell-specific deletion of the ROQUIN RING domain have unchanged Th1, Th2, Th17, and Tregs during a T-dependent response but show a profoundly defective antigen-specific Tfh compartment. ROQUIN RING signaling directly antagonized the catalytic α1 subunit of adenosine monophosphate-activated protein kinase (AMPK), a central stress-responsive regulator of cellular metabolism and mTOR signaling, which is known to facilitate T-dependent humoral immunity. We therefore unexpectedly uncover a ROQUIN–AMPK metabolic signaling nexus essential for selectively promoting Tfh responses.
Publisher: Wiley
Date: 28-09-2007
DOI: 10.1002/9780470515525.CH10
Abstract: Lymphocyte antigen receptors, such as the B cell antigen receptor (BCR), have the ability to promote or inhibit immune responses. This functional plasticity is exemplified by BCR-induced mitosis in naïve but not tolerant B cells and is correlated with biochemical differences in the signals triggered by foreign and self antigens. Acute stimulation of naïve B cells with foreign antigen induces a biphasic Ca2+ flux, and activates nuclear signalling through NF-AT, NF-kappa B, JNK and ERK. In tolerant B lymphocytes, by contrast, self antigen triggers only a low Ca2+ plateau, NF-AT and ERK. After removal from self antigen, the BCRs on tolerant B cells reacquire the ability to stimulate a biphasic Ca2+ flux and to promote proliferation. The differences in nuclear signalling between naïve and tolerant cells is brought about in part by differences in the magnitude of the Ca2+ signal. A low, sustained Ca2+ signal, such as that seen in tolerant B cells, activates NF-AT, whereas, a high but transient Ca2+ spike, which resembles that triggered in naïve B cells, activates NF-kappa B and JNK. These findings demonstrate that the quantitative differences in Ca2+ signalling between naïve and tolerant B cells are reversible and contribute to the differential triggering of nuclear signals. The activation of selected transcription factors may in turn account for the different functional responses triggered in naïve and tolerant lymphocytes.
Publisher: Rockefeller University Press
Date: 12-1997
Abstract: The CD19 cell surface molecule regulates signal transduction events critical for B lymphocyte development and humoral immunity. Increasing the density of CD19 expression renders B lymphocytes hyper-responsive to transmembrane signals, and transgenic mice that overexpress CD19 have increased levels of autoantibodies. The role of CD19 in tolerance regulation and autoantibody generation was therefore examined by crossing mice that overexpress a human CD19 transgene with transgenic mice expressing a model autoantigen (soluble hen egg lysozyme, sHEL) and high-affinity HEL-specific IgMa and IgDa (IgHEL) antigen receptors. In this model of peripheral tolerance, B cells in sHEL/IgHEL double-transgenic mice are functionally anergic and do not produce autoantibodies. However, it was found that overexpression of CD19 in sHEL/IgHEL double-transgenic mice resulted in a breakdown of peripheral tolerance and the production of anti-HEL antibodies at levels similar to those observed in IgHEL mice lacking the sHEL autoantigen. Therefore, altered signaling thresholds due to CD19 overexpression resulted in the breakdown of peripheral tolerance. Thus, CD19 overexpression shifts the balance between tolerance and immunity to autoimmunity by augmenting antigen receptor signaling.
Publisher: Wiley
Date: 05-1995
Abstract: CD38 is a 42-kDa membrane associated enzyme which converts NAD into cyclic ADP-ribose (cADPR), a Ca(2+)-mobilizing second messenger, and ADP-ribose (ADPR). Agonistic antibodies to murine CD38 deliver a potent growth co-stimulus to mature splenic B lymphocytes. In this report we demonstrate a striking relationship between CD38-mediated mitogenesis and the ability of surface IgM to promote B cell proliferation. Tolerized B lymphocytes obtained from a double-transgenic mouse model of B cell tolerance do not proliferate in response to antigen stimulation through the Ig receptor or to agonistic anti-CD38 antibodies. Similarly, B-1 cells isolated from the peritoneal cavity of normal mice, and splenic B cells isolated from newborn mice were also unresponsive to both anti-IgM and anti-CD38 stimulation. All of these CD38-unresponsive B cells expressed normal levels of cell surface CD38 and responded to numerous other stimuli. CD38 immunoprecipitated from these B cell populations was normal in size and effectively hydrolyzed NAD, suggesting that the defect in CD38 signaling likely occurs downstream of CD38 itself. Signaling through CD38 and IgM does not always have identical effects on B cells since anti-CD38 cannot deliver inhibitory growth or differentiation signals to normal B cells or immature B cell lines. Nevertheless, the correlative data with these multiple B cell models of unresponsiveness suggests that the signaling pathway utilized by CD38 and IgM intersect, possibly sharing at least one of the crucial components of the Ig receptor signaling cascade.
Publisher: eLife Sciences Publications, Ltd
Date: 12-12-2013
DOI: 10.7554/ELIFE.01020
Abstract: Missense variants are a major source of human genetic variation. Here we analyze a new mouse missense variant, Rasgrp1Anaef, with an ENU-mutated EF hand in the Rasgrp1 Ras guanine nucleotide exchange factor. Rasgrp1Anaef mice exhibit anti-nuclear autoantibodies and gradually accumulate a CD44hi Helios+ PD-1+ CD4+ T cell population that is dependent on B cells. Despite reduced Rasgrp1-Ras-ERK activation in vitro, thymocyte selection in Rasgrp1Anaef is mostly normal in vivo, although CD44 is overexpressed on naïve thymocytes and T cells in a T-cell-autonomous manner. We identify CD44 expression as a sensitive reporter of tonic mTOR-S6 kinase signaling through a novel mouse strain, chino, with a reduction-of-function mutation in Mtor. Elevated tonic mTOR-S6 signaling occurs in Rasgrp1Anaef naïve CD4+ T cells. CD44 expression, CD4+ T cell subset ratios and serum autoantibodies all returned to normal in Rasgrp1AnaefMtorchino double-mutant mice, demonstrating that increased mTOR activity is essential for the Rasgrp1Anaef T cell dysregulation.
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.JACI.2016.07.016
Abstract: Dedicator of cytokinesis 8 (DOCK8) deficiency is a combined immunodeficiency caused by autosomal recessive loss-of-function mutations in DOCK8. This disorder is characterized by recurrent cutaneous infections, increased serum IgE levels, and severe atopic disease, including food-induced anaphylaxis. However, the contribution of defects in CD4 We sought to investigate the phenotype and function of DOCK8-deficient CD4 We performed in-depth analysis of the CD4 DOCK8-deficient memory CD4 Investigations into the DOCK8-deficient CD4
Publisher: Elsevier BV
Date: 1989
DOI: 10.1016/0952-7915(89)90192-1
Abstract: The neurotransmitter acetylcholine is an important modulator of cognitive functions including attention, learning, and memory. The actions of acetylcholine are mediated by five distinct muscarinic acetylcholine receptor subtypes (M(1)-M(5)). The lack of drugs with a high degree of selectivity for these subtypes has impeded the determination of which subtypes mediate which components of cholinergic neurotransmission relevant to cognitive abilities. The present study examined the behavioral functions of the M(2) muscarinic receptor subtype by utilizing congenic C57BL/6 mice possessing a null-mutation in the M(2) muscarinic receptor gene (M(2)(-/-) mice). Comprehensive assessment of general health and the neurological function found no major differences between M(2)(-/-) and wild-type (M(2)(+/+)) mice. In the tests of learning and memory, M(2)(-/-) mice were impaired in the acquisition (trials to criterion), but not the retention (72h) of a passive avoidance task. In a novel open field, M(2)(-/-) mice were impaired in between-sessions, but not within-session habituation. In a holeboard test of spatial memory, M(2)(-/-) mice committed more errors in working memory than M(2)(+/+) mice. Reference memory did not differ between the genotypes. M(2)(-/-) mice showed no impairments in either cued or contextual fear conditioning. These findings replicate and extend earlier findings in a hybrid strain and solidify the interpretation that the M(2) receptor plays a critical role in specific components of cognitive abilities.
Publisher: Rockefeller University Press
Date: 22-06-2015
DOI: 10.1084/JEM.20142110
Abstract: Studies on the biology of mucosal-associated invariant T cells (MAIT cells) in mice have been h ered by a lack of specific reagents. Using MR1-antigen (Ag) tetramers that specifically bind to the MR1-restricted MAIT T cell receptors (TCRs), we demonstrate that MAIT cells are detectable in a broad range of tissues in C57BL/6 and BALB/c mice. These cells include CD4−CD8−, CD4−CD8+, and CD4+CD8− subsets, and their frequency varies in a tissue- and strain-specific manner. Mouse MAIT cells have a CD44hiCD62Llo memory phenotype and produce high levels of IL-17A, whereas other cytokines, including IFN-γ, IL-4, IL-10, IL-13, and GM-CSF, are produced at low to moderate levels. Consistent with high IL-17A production, most MAIT cells express high levels of retinoic acid–related orphan receptor γt (RORγt), whereas RORγtlo MAIT cells predominantly express T-bet and produce IFN-γ. Most MAIT cells express the promyelocytic leukemia zinc finger (PLZF) transcription factor, and their development is largely PLZF dependent. These observations contrast with previous reports that MAIT cells from Vα19 TCR transgenic mice are PLZF− and express a naive CD44lo phenotype. Accordingly, MAIT cells from normal mice more closely resemble human MAIT cells than previously appreciated, and this provides the foundation for further investigations of these cells in health and disease.
Publisher: Springer Science and Business Media LLC
Date: 20-01-2021
DOI: 10.1038/S41586-021-03218-7
Abstract: Plasma membrane rupture (PMR) is the final cataclysmic event in lytic cell death. PMR releases intracellular molecules known as damage-associated molecular patterns (DAMPs) that propagate the inflammatory response
Publisher: Springer Science and Business Media LLC
Date: 14-11-2016
DOI: 10.1038/NCOMMS13373
Abstract: Continuous contact with self-major histocompatibility complex (MHC) ligands is essential for survival of naïve T cells but not memory cells. This surprising finding implies that T cell subsets may vary in their relative T-cell receptor (TCR) sensitivity. Here we show that in CD8 + T cells TCR sensitivity correlates inversely with levels of CD5, a marker for strong self-MHC reactivity. We also show that TCR sensitivity is lower in memory CD8 + T cells than naïve cells. In both situations, TCR hypo-responsiveness applies only to short-term TCR signalling events and not to proliferation, and correlates directly with increased expression of a phosphatase, CD45 and reciprocal decreased expression of activated LCK. Inhibition by high CD45 on CD8 + T cells may protect against overt TCR auto-MHC reactivity, while enhanced sensitivity to cytokines ensures strong responses to foreign antigens.
Publisher: Elsevier BV
Date: 04-1997
DOI: 10.1016/S1074-7613(00)80285-X
Abstract: It is not known how immunogenic versus tolerogenic cellular responses are signaled by receptors such as the B cell antigen receptor (BCR). Here we compare BCR signaling in naive cells that respond positively to foreign antigen and self-tolerant cells that respond negatively to self-antigen. In naive cells, foreign antigen triggered a large biphasic calcium response and activated nuclear signals through NF-AT, NF-kappa B, JNK, and ERK p90rsk. In tolerant B cells, self-antigen stimulated low calcium oscillations and activated NF-AT and ERK p90rsk but not NF-kappa B or JNK. Self-reactive B cells lacking the phosphatase CD45 did not exhibit calcium oscillations or ERK p90rsk activation, nor did they repond negatively to self-antigen. These data reveal striking biochemical differences in BCR signaling to the nucleus during positive selection by foreign antigens and negative selection by self-antigens.
Publisher: Elsevier BV
Date: 11-1998
DOI: 10.1016/S1074-7613(00)80669-X
Abstract: The role of complement in the maintenance of self-tolerance has been examined in two models: an immunoglobulin transgenic model of peripheral tolerance and a lupus-like murine model of CD95 (Fas) deficiency. We find that self-reactive B lymphocytes deficient in complement receptors CD21/CD35 or transferred into mice deficient in the complement protein C4 are not anergized by soluble self-antigen. In the second model, deficiency in CD21/CD35 or C4 combined with CD95 deficiency results in high titers of anti-nuclear antibodies leading to severe lupus-like disease. These findings suggest a novel role for the complement system in B cell tolerance and provide insight into the genetic association of complement deficiency with susceptibility to systemic lupus erythematosus.
Publisher: The American Association of Immunologists
Date: 11-2007
Publisher: Elsevier BV
Date: 07-1998
DOI: 10.1016/S1074-7613(00)80586-5
Abstract: Self-reactive B cells Tg for both a bcl-xL death inhibitory gene and an Ig receptor recognizing hen egg lysozyme (HEL-Ig) efficiently escaped developmental arrest and deletion in mice expressing membrane-bound self-antigen (mHEL). In response to the same antigen, Tg HEL-Ig B cells not expressing bcl-xL were deleted, while cells expressing bcl-2 were arrested at the immature B stage. Bcl-xL Tg B cells escaping negative selection were anergic in both in vitro and in vivo assays and showed some evidence for receptor editing. These studies suggest that Bcl-x may have a distinct role in controlling survival at the immature stage of B cell development and demonstrate that tolerance is preserved when self-reactive B cells escape central deletion.
Publisher: Springer Science and Business Media LLC
Date: 20-03-2011
DOI: 10.1038/NI.2011
Publisher: Elsevier BV
Date: 10-2018
Publisher: American Diabetes Association
Date: 18-07-2011
DOI: 10.2337/DB10-1344
Abstract: To define cellular mechanisms by which B cells promote type 1 diabetes. The study measured islet-specific CD4 T cell regulation in T-cell receptor transgenic mice with elevated frequencies of CD4 T cells recognizing hen egg lysozyme (HEL) autoantigen expressed in islet β-cells and thymic epithelium under control of the insulin-gene promoter. The effects of a mutation in Roquin that dysregulates T follicular helper (Tfh) cells to promote B-cell activation and anti-islet autoantibodies were studied, as were the effects of HEL antigen–presenting B cells and passively transferred or maternally transmitted anti-islet HEL antibodies. Mouse anti-islet IgG antibodies—either formed as a consequence of excessive Tfh activity, maternally transmitted, or passively transferred—caused a breakdown of tolerance in islet-reactive CD4+ cells and fast progression to diabetes. Progression to diabetes was ameliorated in the absence of B cells or when the B cells could not secrete islet-specific IgG. Anti-islet antibodies increased the survival of proliferating islet-reactive CD4+ T cells. FcγR blockade delayed and reduced the incidence of autoimmune diabetes. B cells can promote type 1 diabetes by secreting anti-islet autoantibodies that act in an FcγR-mediated manner to enhance the expansion of islet-reactive CD4 T cells and cooperate with inherited defects in thymic and peripheral CD4 T–cell tolerance. Cooperation between inherited variants affecting CD4 T–cell tolerance and anti-islet autoantibodies should be examined in epidemiological studies and in studies examining the efficacy of B-cell depletion.
Publisher: Springer Science and Business Media LLC
Date: 04-2002
DOI: 10.1038/416595A
Publisher: American Society for Clinical Investigation
Date: 06-09-2016
DOI: 10.1172/JCI85774
Publisher: Springer Science and Business Media LLC
Date: 29-10-2003
DOI: 10.1038/NI1001
Publisher: Wiley
Date: 06-02-2014
DOI: 10.1002/PATH.4308
Abstract: The study of mutations causing the steroid‐resistant nephrotic syndrome in children has greatly advanced our understanding of the kidney filtration barrier. In particular, these genetic variants have illuminated the roles of the podocyte, glomerular basement membrane and endothelial cell in glomerular filtration. However, in a significant number of familial and early onset cases, an underlying mutation cannot be identified, indicating that there are likely to be multiple unknown genes with roles in glomerular permeability. We now show how the combination of N ‐ethyl‐ N ‐nitrosourea mutagenesis and next‐generation sequencing could be used to identify the range of mutations affecting these pathways. Using this approach, we isolated a novel mouse strain with a viable nephrotic phenotype and used whole‐genome sequencing to isolate a causative hypomorphic mutation in Lamb2 . This discovery generated a model for one part of the spectrum of human Pierson's syndrome and provides a powerful proof of principle for accelerating gene discovery and improving our understanding of inherited forms of renal disease. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd
Publisher: Cold Spring Harbor Laboratory
Date: 24-09-2018
DOI: 10.1101/424945
Abstract: High-throughput single-cell RNA-Sequencing is a powerful technique for gene expression profiling of complex and heterogeneous cellular populations such as the immune system. However, these methods only provide short-read sequence from one end of a cDNA template, making them poorly suited to the investigation of gene-regulatory events such as mRNA splicing, adaptive immune responses or somatic genome evolution. To address this challenge, we have developed a method that combines targeted long-read sequencing with short-read based transcriptome profiling of barcoded single cell libraries generated by droplet-based partitioning. We use Repertoire And Gene Expression sequencing (RAGE-seq) to accurately characterize full-length T cell (TCR) and B cell (BCR) receptor sequences and transcriptional profiles of more than 7,138 lymphocytes s led from the primary tumour and draining lymph node of a breast cancer patient. With this method we show that somatic mutation, alternate splicing and clonal evolution of T and B lymphocytes can be tracked across these tissue compartments. Our results demonstrate that RAGE-Seq is an accessible and cost-effective method for high-throughput deep single cell profiling, applicable to a wide range of biological challenges.
Publisher: Rockefeller University Press
Date: 21-10-2002
DOI: 10.1084/JEM.20020959
Abstract: The number of circulating follicular B lymphocytes is normally kept within a precise range despite their dispersion through the body and daily overproduction of precursors in the bone marrow. By establishing a genome wide recessive mutation screen in C57BL/6 mice to identify critical components of immune system regulation, we identified a mutant strain with selective deficiency in recirculating B cells but not immature or peritoneal B1 cells. Analysis of mixed bone marrow chimeras established that the mutation affects a cell autonomous process within B cells that is required for their accumulation after emigrating to peripheral lymphoid organs. The defect is caused by a point mutation in the gene encoding transcription factor nuclear factor (NF)-κB2, terminating the encoded protein within the DNA-binding domain. These findings establish the feasibility of analyzing immune regulation by genome wide mutant screens and demonstrates an intrinsic requirement for NF-κB2 in regulating circulating follicular B cell numbers.
Publisher: eLife Sciences Publications, Ltd
Date: 24-10-2014
DOI: 10.7554/ELIFE.03549
Abstract: The generation of naïve T lymphocytes is critical for immune function yet the mechanisms governing their maturation remain incompletely understood. We have identified a mouse mutant, bloto, that harbors a hypomorphic mutation in the zinc finger protein Zfp335. Zfp335bloto/bloto mice exhibit a naïve T cell deficiency due to an intrinsic developmental defect that begins to manifest in the thymus and continues into the periphery, affecting T cells that have recently undergone thymic egress. The effects of Zfp335bloto are multigenic and cannot be attributed to altered thymic selection, proliferation or Bcl2-dependent survival. Zfp335 binds to promoter regions via a consensus motif, and its target genes are enriched in categories related to protein metabolism, mitochondrial function, and transcriptional regulation. Restoring the expression of one target, Ankle2, partially rescues T cell maturation. These findings identify Zfp335 as a transcription factor and essential regulator of late-stage intrathymic and post-thymic T cell maturation.
Publisher: Wiley
Date: 25-11-2014
DOI: 10.1002/ART.38824
Abstract: Objective. Systemic lupus erythematosus (SLE) isa chronic and heterogeneous autoimmune disease. Both twin and sibling studies indicate a strong genetic contribution to lupus, but in the majority of cases the pathogenic variant remains to be identified. The genetic contribution to disease is likely to be greatest in cases with early onset and severe phenotypes. Whole-exome sequencing now offers the possibility of identifying rare alleles responsible for disease in such cases. This study was undertaken to identify genetic causes of SLE using whole-exome sequencing.Methods. We performed whole-exome sequencing in a 4-year-old girl with early-onset SLE and conducted biochemical analysis of the putative defect.Results. Whole-exome sequencing in a 4-year-old girl with cerebral lupus identified a rare, homozygous mutation in the three prime repair exonuclease 1 gene(TREX1) that was predicted to be highly deleterious.The TREX1 R97H mutant protein had a 20-fold reduction in exonuclease activity and was associated with an elevated interferon-alpha signature in the patient.The discovery and characterization of a pathogenic TREX1 variant in our proband has therapeutic implications.The patient is now a candidate for therapy. Conclusion. Our study is the first to demonstrate that whole-exome sequencing can be used to identify rare or novel deleterious variants as genetic causes of SLE and, through a personalized approach, improve therapeutic options.
Publisher: American Society of Hematology
Date: 12-2006
DOI: 10.1182/BLOOD-2006-02-004531
Abstract: Despite the importance of thymic stromal cells to T-cell development, relatively little is known about their biology. Here, we use single-cell analysis of stromal cells to analyze extensive changes in the number and composition of thymic stroma throughout life, revealing a surprisingly dynamic population. Phenotypic progression of thymic epithelial subsets was assessed at high resolution in young mice to provide a developmental framework. The cellular and molecular requirements of adult epithelium were studied, using various mutant mice to demonstrate new cross talk checkpoints dependent on RelB in the cortex and CD40 in the medulla. With the use of Ki67 and BrdU labeling, the turnover of thymic epithelium was found to be rapid, but then diminished on thymic involution. The various defects in stromal turnover and composition that accompanied involution were rapidly reversed following sex steroid ablation. Unexpectedly, mature cortical and medullary epithelium showed a potent capacity to stimulate naive T cells, comparable to that of thymic dendritic cells. Overall, these studies show that the thymic stroma is a surprisingly dynamic population and may have a more direct role in negative selection than previously thought.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 21-05-2019
DOI: 10.1126/SCISIGNAL.AAX4917
Abstract: Pyroptosis requires the induction of gasdermin D expression by the transcription factor IRF2.
Publisher: Proceedings of the National Academy of Sciences
Date: 05-1987
Abstract: To produce sufficient quantities of soluble T-cell receptor protein for detailed biochemical and biophysical analyses we have explored the use of immunoglobulin--T-cell receptor gene fusions. In this report we describe a chimeric gene construct containing a T-cell receptor alpha-chain variable (V) domain and the constant (C) region coding sequences of an immunoglobulin gamma 2a molecule. Cells transfected with the chimeric gene synthesize a stable protein product that expresses immunoglobulin and T-cell receptor antigenic determinants as well as protein A binding sites. We show that the determinant recognized by the anticlonotypic antibody A2B4.2 resides on the V alpha domain of the T-cell receptor. The chimeric protein associates with a normal lambda light chain to form an apparently normal tetrameric (H2L2, where H = heavy and L = light) immunoglobulin molecule that is secreted. Also of potential significance is the fact that a T-cell receptor V beta gene in the same construct is neither assembled nor secreted with the lambda light chain, and when expressed with a C kappa region it does not assemble with the chimeric V alpha C gamma 2a protein mentioned above. This indicates that not all T-cell receptor V regions are similar enough to immunoglobulin V regions for them to be completely interchangeable.
Publisher: American Society of Hematology
Date: 06-11-2014
DOI: 10.1182/BLOOD-2014-06-578542
Abstract: A novel NFKB2 mutation confers a severe B-cell deficiency, but antibody production is partially preserved. Unprocessed p100 results in an IκB-like action on the canonical nuclear factor-κB pathway.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 19-01-1996
DOI: 10.1126/SCIENCE.271.5247.348
Abstract: An optimal immune response should differentiate between harmful and innocuous antigens. Primitive systems of innate immunity, such as the complement system, may play a role in this distinction. When activated, the C3 component of complement attaches to potential antigens on microorganisms. To determine whether this alters acquired immune recognition, mice were immunized with a recombinant model antigen, hen egg lysozyme (HEL), fused to murine C3d. HEL bearing two and three copies of C3d was 1000- and 10,000-fold more immunogenic, respectively, than HEL alone. Thus, C3d is a molecular adjuvant of innate immunity that profoundly influences an acquired immune response.
Publisher: Elsevier BV
Date: 1995
DOI: 10.1016/1074-7613(95)90075-6
Abstract: Motheaten viable (mev) mice are deficient in the cytosolic protein tyrosine phosphatase, PTP1C, and exhibit severe B cell immunodeficiency and autoantibody production. The role of PTP1C in B cell selection and function was analyzed by breeding immunoglobulin transgenes specific for a defined antigen, hen egg lysozyme, into mev mice. Antigen triggered a greater and more rapid elevation of intracellular calcium in PTP1C-deficient B cells, indicating that this phosphatase negatively regulates immunoglobulin signaling. Elimination of self-reactive B cells carrying this signal-enhancing mutation was triggered during their development by binding a lower valency form of self-antigen than is normally required. These findings establish that activation of distinct repertoire-censoring mechanisms depends on quantitative differences in antigen receptor signaling, whose thresholds are determined by negative regulation through PTP1C.
Publisher: Rockefeller University Press
Date: 20-03-2000
Abstract: Conserved differences between the transmembrane and cytoplasmic domains of membrane immunoglobulin (Ig)M and IgG may alter the function of antigen receptors on naive versus memory B cells. Here, we compare the ability of these domains to signal B cell allelic exclusion and maturation in transgenic mice. A lysozyme-binding antibody was expressed in parallel sets of mice as IgM, IgG1, or a chimeric receptor with IgM extracellular domains and transmembrane/cytoplasmic domains of IgG1. Like IgM, the IgG1 or chimeric IgM/G receptors triggered heavy chain allelic exclusion and supported development of mature CD21+ B cells. Many of the IgG or IgM/G B cells became CD21high and downregulated their IgG and IgM/G receptors spontaneously, resembling memory B cells and B cells with mutations that exaggerate B cell antigen receptor signaling. Unlike IgM-transgenic mice, “edited” B cells that carry non–hen egg lysozyme binding receptors preferentially accumulated in IgG and IgM/G mice. This was most extreme in lines with the highest transgene copy number and diminished in variant offspring with fewer copies. The sensitivity of B cell maturation to transgene copy number conferred by the IgG transmembrane and cytoplasmic domains may explain the erse phenotypes found in other IgG-transgenic mouse strains and may reflect exaggerated signaling.
Publisher: Proceedings of the National Academy of Sciences
Date: 15-04-1991
Abstract: An in vitro model was used to investigate the potential for different structural forms of endogenous antigen to be processed and presented by major histocompatibility complex class II molecules. For this purpose the class II-restricted presentation of an immunodominant epitope of hen egg lysozyme [HEL-(46-61)] was studied in class II-positive B-lymphoma cells (M12.C3) transfected with genes encoding HEL molecules either (i) secreted in high (hi) or low (lo) amounts as soluble antigen [sHEL(hi/lo)], (ii) localized within the endoplasmic reticulum (ER)/salvage compartment (ER-HEL), or (iii) anchored on the cell surface as an integral membrane protein (mHEL). The corresponding sHEL, ER-HEL, and mHEL gene products were expressed as predicted except that HEL determinants accumulated in the culture supernatant as well as on the cell membrane of mHEL-transfected cells. Class II-positive cells endogenously expressing all three forms of HEL antigen constitutively presented the immunodominant HEL-(46-61) determinant with differential efficiency (mHEL, sHEL greater than ERHEL) to a class II-restricted T hybridoma. A second T hybridoma recognized endogenous HEL-(46-61) determinants constitutively presented on sHEL(hi) and mHEL transfectants but not on sHEL(lo) or ERHEL transfectants. The formation of HEL-(46-61)/I-Ak complexes in the ERHEL and sHEL(lo) transfectants was therefore limiting. Mixing experiments with different antigen-presenting cells indicated that the HEL-(46-61) determinant was derived from endogenous antigen rather than by reuptake of shed or secreted HEL determinants. We conclude that MHC class II molecules can present some antigenic determinants derived from endogenous proteins that are sequestered in the ER/salvage compartment as well as distally transported in the form of secretory or membrane antigens.
Publisher: Wiley
Date: 16-10-2008
Abstract: Selection of B cells subjected to hypermutation in germinal centres (GC) during T cell-dependent (TD) antibody responses yields memory cells and long-lived plasma cells that produce high affinity antibodies biased to foreign antigens rather than self-antigens. GC also form in T-independent (TI) responses to polysaccharide antigens but failed selection results in GC involution and memory cells are not generated. To date there are no markers that allow phenotypic distinction of T-dependent and TI germinal centre B cells. We compared the global gene expression of GC B cells purified from mice immunized with either TD or TI antigens and identified eighty genes that are differentially expressed in TD GC. Significantly, the largest cluster comprises genes involved in growth and guidance of neuron axons such as Plexin B2, Basp1, Nelf, Shh, Sc4mol and Sult4alpha. This is consistent with formation of long neurite (axon and dendrite)-like structures by mouse and human GC B cells, which may facilitate T:B cell interactions within GC, affinity maturation and B cell memory formation. Expression of BASP1 and PLEXIN B2 protein is very low or undetectable in resting and TI GC B cells, but markedly upregulated in GC B cells induced in the presence of T cell help. Finally we show some of the axon growth genes upregulated in TD-GC B cells including Basp1, Shh, Sult4alpha, Sc4mol are also preferentially expressed in post-GC B cell neoplasms.
Publisher: Rockefeller University Press
Date: 07-1986
Abstract: We have analyzed a series of mutants derived from a KLH-specific, I-E-restricted T hybridoma (FN1-18) which have lost antigen-reactivity while retaining both T cell receptor idiotypic determinants and the ability to respond to Con A. The variants have not gained any detectable alloreactivity, nor is there an obvious lesion in the mutants' beta chain DNA containing the utilized beta chain genes. This loss of antigen reactivity is due to a failure of stable production of the specific V beta-containing mRNA. Our results indicate that in FN1-18, the T cell receptor antigenic determinants are most likely carried by the alpha chain alone or by a complementation product of the V alpha FN1-18 with the V beta of BW5147. V beta FN1-18 represents a previously undescribed T cell receptor V region.
Publisher: Elsevier BV
Date: 03-2007
Publisher: American Society of Hematology
Date: 19-02-2009
DOI: 10.1182/BLOOD-2007-11-120402
Abstract: Hereditary forms of iron-deficiency anemia, including animal models, have taught us much about the normal physiologic control of iron metabolism. However, the discovery of new informative mutants is limited by the natural mutation frequency. To address this limitation, we have developed a screen for heritable abnormalities of red blood cell morphology in mice with single-nucleotide changes induced by the chemical mutagen ethylnitrosourea (ENU). We now describe the first strain, fragile-red, with hypochromic microcytic anemia resulting from a Y228H sub-stitution in the ferrireductase Steap3 (Steap3Y288H). Analysis of the Steap3Y288H mutant identifies a conserved motif required for targeting Steap3 to internal compartments and highlights how phenotypic screens linked to mutagenesis can identify new functional variants in erythropoiesis and ascribe function to previously unidentified motifs.
Publisher: Springer Science and Business Media LLC
Date: 02-2008
DOI: 10.1038/NATURE06547
Abstract: Somatic hypermutation introduces point mutations into immunoglobulin genes in germinal centre B cells during an immune response. The reaction is initiated by cytosine deamination by the activation-induced deaminase (AID) and completed by error-prone processing of the resulting uracils by mismatch and base excision repair factors. Somatic hypermutation represents a threat to genome integrity and it is not known how the B cell genome is protected from the mutagenic effects of somatic hypermutation nor how often these protective mechanisms fail. Here we show, by extensive sequencing of murine B cell genes, that the genome is protected by two distinct mechanisms: selective targeting of AID and gene-specific, high-fidelity repair of AID-generated uracils. Numerous genes linked to B cell tumorigenesis, including Myc, Pim1, Pax5, Ocab (also called Pou2af1), H2afx, Rhoh and Ebf1, are deaminated by AID but escape acquisition of most mutations through the combined action of mismatch and base excision repair. However, approximately 25% of expressed genes analysed were not fully protected by either mechanism and accumulated mutations in germinal centre B cells. Our results demonstrate that AID acts broadly on the genome, with the ultimate distribution of mutations determined by a balance between high-fidelity and error-prone DNA repair.
Publisher: Springer Science and Business Media LLC
Date: 12-05-2017
DOI: 10.1038/CDD.2017.38
Publisher: American Society of Hematology
Date: 09-2011
DOI: 10.1182/BLOOD-2010-06-286393
Abstract: To investigate the role of Aire in thymic selection, we examined the cellular requirements for generation of ovalbumin (OVA)–specific CD4 and CD8 T cells in mice expressing OVA under the control of the rat insulin promoter. Aire deficiency reduced the number of mature single-positive OVA-specific CD4+ or CD8+ T cells in the thymus, independent of OVA expression. Importantly, it also contributed in 2 ways to OVA-dependent negative selection depending on the T-cell type. Aire-dependent negative selection of OVA-specific CD8 T cells correlated with Aire-regulated expression of OVA. By contrast, for OVA-specific CD4 T cells, Aire affected tolerance induction by a mechanism that operated independent of the level of OVA expression, controlling access of antigen presenting cells to medullary thymic epithelial cell (mTEC)–expressed OVA. This study supports the view that one mechanism by which Aire controls thymic negative selection is by regulating the indirect presentation of mTEC-derived antigens by thymic dendritic cells. It also indicates that mTECs can mediate tolerance by direct presentation of Aire-regulated antigens to both CD4 and CD8 T cells.
Publisher: Wiley
Date: 23-11-2020
DOI: 10.1111/IMCB.12419
Publisher: Rockefeller University Press
Date: 13-06-2016
DOI: 10.1084/JEM.20151978
Abstract: Clonal anergy is an enigmatic self-tolerance mechanism because no apparent purpose is served by retaining functionally silenced B cells bearing autoantibodies. Human autoantibodies with IGHV4-34*01 heavy chains bind to poly-N-acetyllactosamine carbohydrates (I/i antigen) on erythrocytes and B lymphocytes, cause cold agglutinin disease, and are carried by 5% of naive B cells that are anergic. We analyzed the specificity of three IGHV4-34*01 IgG antibodies isolated from healthy donors immunized against foreign rhesus D alloantigen or vaccinia virus. Each IgG was expressed and analyzed either in a hypermutated immune state or after reverting each antibody to its unmutated preimmune ancestor. In each case, the preimmune ancestor IgG bound intensely to normal human B cells bearing I/i antigen. Self-reactivity was removed by a single somatic mutation that paradoxically decreased binding to the foreign immunogen, whereas other mutations conferred increased foreign binding. These data demonstrate the existence of a mechanism for mutation away from self-reactivity in humans. Because 2.5% of switched memory B cells use IGHV4-34*01 and & % of these have mutations that remove I/i binding, clonal redemption of anergic cells appears efficient during physiological human antibody responses.
Publisher: Springer Science and Business Media LLC
Date: 09-2000
DOI: 10.1038/35030187
Publisher: Rockefeller University Press
Date: 05-1994
Abstract: Successful antibody production in vivo depends on a number of cellular events, one of the most important of these being cognate B cell-T cell interaction. To examine this phenomenon in vitro, homogeneous populations of hen egg lysozyme (HEL)-specific small resting B cells and naive CD4+ HEL-specific T cells (derived from immunoglobulin [Ig] and T cell receptor transgenic mice, respectively) were cultured together. On addition of intact HEL protein. HEL-specific B cells increase their expression of activation molecules, including a B7-related protein and CD44, and enlarge into blast cells. Within the same cultures, HEL-specific CD4+ T cells also increase expression of the activation markers CD69 and CD44, enlarge, secrete lymphokines, and proliferate. This response is radiation sensitive, supporting the conclusion that HEL-specific B cells present antigen to and activate the naive T cells. By contrast, when a synthetic peptide fragment of HEL is used to bypass B cell antigen-receptor engagement, the naive T cells enlarge and display activation antigens, but fail to produce lymphokines, proliferate, or promote B cell blastogenesis. Presentation of HEL by tolerant B cells, which are no longer able to signal effectively through their antigen receptors, results in an identical pattern of incomplete T cell activation. Addition of a stimulating anti-CD28 antibody and blocking of CD28 signals with CTLA4/Ig fusion protein both show that complete activation of naive CD4+ T cells depends on the initial induction of B7 and related costimulatory molecules after HEL binding to nontolerant HEL-specific B cells. Thus, in the absence of adequate constimulation from the B cell, naive CD4+ T cells undergo a form of "partial activation" in which they upregulate surface expression of certain T cell activation antigens, but fail to efficiently produce lymphokine and proliferate. This may explain the different conclusions that have been reached regarding the consequences of B cell antigen presentation to T cells, in that the ability of B cells to activate naive CD4+ T cells depends both on their specificity and their activation state.
Publisher: Springer Science and Business Media LLC
Date: 26-09-2016
DOI: 10.1038/NI.3565
Abstract: Mucosal-associated invariant T cells (MAIT cells) detect microbial vitamin B2 derivatives presented by the antigen-presenting molecule MR1. Here we defined three developmental stages and checkpoints for the MAIT cell lineage in humans and mice. Stage 1 and stage 2 MAIT cells predominated in thymus, while stage 3 cells progressively increased in abundance extrathymically. Transition through each checkpoint was regulated by MR1, whereas the final checkpoint that generated mature functional MAIT cells was controlled by multiple factors, including the transcription factor PLZF and microbial colonization. Furthermore, stage 3 MAIT cell populations were expanded in mice deficient in the antigen-presenting molecule CD1d, suggestive of a niche shared by MAIT cells and natural killer T cells (NKT cells). Accordingly, this study maps the developmental pathway and checkpoints that control the generation of functional MAIT cells.
Publisher: Springer Science and Business Media LLC
Date: 04-04-2013
DOI: 10.1038/GENE.2013.11
Publisher: Springer Science and Business Media LLC
Date: 08-11-2009
DOI: 10.1038/NI.1820
Publisher: Public Library of Science (PLoS)
Date: 08-11-2017
Publisher: Wiley
Date: 09-2014
DOI: 10.1111/JMWH.12249
Publisher: Elsevier BV
Date: 05-1996
DOI: 10.1016/S0960-9822(02)00531-6
Abstract: Recent results show that immune responses can be induced in neonatal mice. Do they really refute the traditional view that the ability to discriminate between 'self' and 'non-self' is a fundamental property of the immune system?
Publisher: American Association for the Advancement of Science (AAAS)
Date: 13-04-2018
Abstract: Antibodies distinguish foreign epitopes from closely related self-antigens by poorly understood mechanisms. In mice, Burnett et al. found that a proportion of B cells could cross-react with similar foreign and self-antigens (see the Perspective by Kara and Nussenzweig). Challenge with self-antigen resulted in anergy (i.e., a lack of immune response), which was reversed by exposure to high-density foreign antigen. Mutations that decreased self-affinity were rapidly selected for, whereas selection for epistatic mutations that enhanced foreign reactivity took longer. Self-reactivity, rather than being an impediment to immunization, resulted in higher affinities against a foreign immunogen. Science , this issue p. 223 see also p. 152
Publisher: Public Library of Science (PLoS)
Date: 04-10-2012
Publisher: Cold Spring Harbor Laboratory
Date: 03-08-2023
DOI: 10.1101/2023.08.02.551154
Abstract: The expanding number of rare immunodeficiency syndromes offers an opportunity to understand key genes that support immune defence against infectious diseases. However, patients with these diseases are by definition rare. In addition, any analysis is complicated by treatments and co-morbid infections requiring the use of mouse models for detailed investigations. Here we develop a mouse model of DOCK2 immunodeficiency and demonstrate that these mice have delayed clearance of herpes simplex virus type 1 (HSV-1) infections. Further, we found that they have a critical, cell intrinsic role of DOCK2 in the clonal expansion of anti-viral CD8 + T cells despite normal early activation of these cells. Finally, while the major deficiency is in clonal expansion, the ability of primed and expanded DOCK2-deficient CD8 + T cells to protect against HSV-1-infection is also compromised. These results provide a contributing cause for the frequent and devastating viral infections seen in DOCK2-deficient patients and improve our understanding of anti-viral CD8 + T cell immunity.
Publisher: Springer Science and Business Media LLC
Date: 2007
Publisher: Wiley
Date: 05-09-2008
Publisher: Elsevier BV
Date: 2022
DOI: 10.1016/J.CELREP.2021.110259
Abstract: CD21
Publisher: Wiley
Date: 19-04-2010
DOI: 10.1111/J.1742-4658.2010.07628.X
Abstract: Roquin is an E3 ubiquitin ligase with a poorly understood but essential role in preventing T-cell-mediated autoimmune disease and in microRNA-mediated repression of inducible costimulator (Icos) mRNA. Roquin and its mammalian paralogue membrane-associated nucleic acid binding protein (MNAB) define a protein family distinguished by an approximately 200 amino acid domain of unknown function, ROQ, that is highly conserved from mammals to invertebrates and is flanked by a RING-1 zinc finger and a CCCH zinc finger. Here we show that human, Drosophila and Caenorhabditis elegans Roquin and human MNAB localize to the cytoplasm and upon stress are concentrated in stress granules, where stalled mRNA translation complexes are stored. The ROQ domain is necessary and sufficient for localization to arsenite-induced stress granules and to induce these structures upon overexpression, and is required to trigger Icos mRNA decay. Gel-shift, SPR and footprinting studies show that an N-terminal fragment centred on the ROQ domain binds RNA from the Icos 3'-untranslated region comprising the minimal sequence for Roquin-mediated repression, adjacent to the miR-101 sequence complementarity. These findings identify Roquin as an RNA-binding protein and establish a specific function for the ROQ protein domain in mRNA homeostasis. Structured digital abstract * MINT-7711163: TIA-1 (uniprotkb:P31483) and Roquin (uniprotkb:Q4VGL6) colocalize (MI:0403) by fluorescence microscopy (MI:0416) * MINT-7711475: RLE-1 (uniprotkb:O45962) and TIA-1 (uniprotkb:P31483) colocalize (MI:0403) by fluorescence microscopy (MI:0416) * MINT-7711487: DmRoquin (uniprotkb:Q9VV48) and TIA-1 (uniprotkb:P31483) colocalize (MI:0403) by fluorescence microscopy (MI:0416) * MINT-7711447, MINT-7711460: MNAB (uniprotkb:Q9HBD1) and TIA-1 (uniprotkb:P31483) colocalize (MI:0403) by fluorescence microscopy (MI:0416) * MINT-7711176: eIF3 (uniprotkb:P55884) and Roquin (uniprotkb:Q4VGL6) colocalize (MI:0403) by fluorescence microscopy (MI:0416) * MINT-7711192: DCP1A (uniprotkb:Q9NPI6) and TIA-1 (uniprotkb:P31483) colocalize (MI:0403) by fluorescence microscopy (MI:0416).
Publisher: Elsevier BV
Date: 09-2001
DOI: 10.1016/S1074-7613(01)00199-6
Abstract: A complete list of molecular components for immune system function is now available with the completion of the human and mouse genome sequences. However, identification and functional annotation of genes involved in immunological processes require a discovery methodology that can efficiently and broadly analyze the complex interplay of these components in vivo. Our recent experience indicates that genome-wide chemical mutagenesis in the mouse is an extremely powerful methodology for the identification of genes required for complex immunological processes.
Publisher: Public Library of Science (PLoS)
Date: 04-03-2008
Publisher: American Association for the Advancement of Science (AAAS)
Date: 16-06-2006
Publisher: Springer Science and Business Media LLC
Date: 13-05-2021
DOI: 10.1038/S41467-021-23044-9
Abstract: Chronic stimulation of CD8 + T cells triggers exhaustion, a distinct differentiation state with diminished effector function. Exhausted cells exist in multiple differentiation states, from stem-like progenitors that are the key mediators of the response to checkpoint blockade, through to terminally exhausted cells. Due to its clinical relevance, there is substantial interest in defining the pathways that control differentiation and maintenance of these subsets. Here, we show that chronic antigen induces the anergy-associated transcription factor EGR2 selectively within progenitor exhausted cells in both chronic LCMV and tumours. EGR2 enables terminal exhaustion and stabilizes the exhausted transcriptional state by both direct EGR2-dependent control of key exhaustion-associated genes, and indirect maintenance of the exhausted epigenetic state. We show that EGR2 is a regulator of exhaustion that epigenetically and transcriptionally maintains the differentiation competency of progenitor exhausted cells.
Publisher: Springer Science and Business Media LLC
Date: 25-12-2010
DOI: 10.1007/S00335-010-9312-4
Abstract: This issue of Mammalian Genome explores the genetic approach to infectious disease susceptibility as it has been applied in mammals. Although no single issue of any journal could give comprehensive treatment to a field so extensive and rapidly growing as this one, these texts describe key discoveries that provided new understanding of immune responses. Classical genetic studies opened and continue to pave the way to deep understanding of many issues in immunology.
Publisher: Elsevier BV
Date: 04-2002
DOI: 10.1016/S0952-7915(02)00331-X
Abstract: The draft sequence of the human and mouse genomes provides an unparalleled opportunity for understanding the genetic control of immune-cell development. Strategies can begin with a gene sequence and pursue a putative immune-system function by employing mRNA-expression profiling or creating gene knockouts in embryonic stem cells. The latter can be produced by utilising the Cre/Lox system, a tetracycline operon, a gene-trap method or chemical mutagenesis. Alternatively, mutant phenotypes (derived using the mutagen ethylnitrosourea) can be traced back to gene sequences.
Publisher: Elsevier BV
Date: 12-1995
DOI: 10.1016/1074-7613(95)90059-4
Abstract: Anergic self-reactive B cells competing within a polyclonal B cell repertoire fail to migrate into primary follicles and die after 1-3 days residence in T cell zones. Transfer of anergic HEL-specific B cells to recipients lacking HEL autoantigen and continuous bromodeoxyuridine labeling in mixed bone marrow chimeras confirms that follicular exclusion and cell death in 1-3 days is not an intrinsic characteristic of anergic cells but results from competition with B cells bearing other specificities together with continued binding of autoantigen. When naive (nontolerant) HEL-specific B cells were transferred into mice expressing HEL autoantigen, they were also excluded from follicles and their lifespan was dramatically shortened, although they became activated to express CD86 (B7-2/B70). In the presence of helper T cells, activated B cells but not anergic B cells were rescued from death and formed large extrafollicular foci to autoantibody-secreting cells. Antigen-induced exclusion from follicles is therefore an independent process from anergy that prevents self-reactive B cells from recirculating in the long-lived repertoire and may foster interactions with T cells during immune responses. By contrast, anergy prevents self-reactive B cells from collaborating with helper T cells and secreting autoantibody while trapped in the T zone.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Springer Science and Business Media LLC
Date: 06-2005
DOI: 10.1038/NATURE03724
Abstract: The mammalian immune system has an extraordinary potential for making receptors that sense and neutralize any chemical entity entering the body. Inevitably, some of these receptors recognize components of our own body, and so cellular mechanisms have evolved to control the activity of these 'forbidden' receptors and achieve immunological self tolerance. Many of the genes and proteins involved are conserved between humans and other mammals. This provides the bridge between clinical studies and mechanisms defined in experimental animals to understand how sets of gene products coordinate self-tolerance mechanisms and how defects in these controls lead to autoimmune disease.
Publisher: The American Association of Immunologists
Date: 15-10-2006
DOI: 10.4049/JIMMUNOL.177.8.5337
Abstract: Differentiation of B cells into plasma cells represents a critical immunoregulatory checkpoint where neutralizing Abs against infectious agents must be selected whereas self-reactive Abs are suppressed. Bacterial LPS is a uniquely potent bacterial immunogen that can bypass self-tolerance within the T cell repertoire. We show here that during LPS-induced plasma cell differentiation, the ERK intracellular signaling pathway serves as a pivotal switch integrating opposing inputs from Ag via BCR and from the two best characterized B cell differentiation factors made by T cells, IL-2 and IL-5. Continuous Ag receptor signaling through the RAS/MEK/ERK pathway, as occurs in self-reactive B cells, inhibits LPS induction of Blimp-1 and the plasma cell differentiation program. Differentiation resumes after a transient pulse of Ag-ERK signaling, or upon inactivation of ERK by IL-2 and IL-5 through induction of dual-specificity phosphatase 5 (Dusp5). The architecture of this molecular switch provides a framework for understanding the specificity of antibacterial Ab responses and resistance to bacterially induced autoimmune diseases such as Guillain-Barré syndrome.
Publisher: American Society of Hematology
Date: 22-09-2016
DOI: 10.1182/BLOOD-2016-03-708065
Abstract: Inhibiting endosomal TLRs suppresses MYD88L265P B-cell proliferation in vitro. Inhibition of endosomal TLRs paradoxically enhances accumulation of MYD88L265P B cells as plasmablasts in vivo.
Publisher: Wiley
Date: 19-08-2010
Publisher: Proceedings of the National Academy of Sciences
Date: 13-01-2014
Abstract: Advances in organ transplantation and treatment of allergy and autoimmune disease hinge upon harnessing a physiological switch that allows T cells to decide between proliferating extensively or actively becoming tolerant. The experiments presented here illuminate a critical element of this natural switch, Ndfip1 (neural precursor cell expressed, developmentally down-regulated protein 4 family-interacting protein 1), a partner protein of ubiquitin ligases induced during the first several isions after T cells encounter antigen. They define the cellular action of Ndfip1 in vivo, acting within iding helper T cells that have responded to innocuous foreign or self-antigen that should normally be tolerated, to force their exit from cell cycle before they have ided so many times that they acquire tissue-damaging effector functions.
Publisher: Elsevier BV
Date: 2010
Publisher: American Association for the Advancement of Science (AAAS)
Date: 31-03-2017
DOI: 10.1126/SCIIMMUNOL.AAJ1996
Abstract: LFA-1 expression allows liver-resident CD8 + T cells to patrol hepatic sinusoids yet remain in the liver.
Publisher: Wiley
Date: 10-1998
DOI: 10.1046/J.1440-1711.1998.00774.X
Abstract: The expression of CD95 (Fas/APO-1) on B cells has been shown to play a direct role in their fate. B cells that chronically bind antigen due to prolonged antigen exposure, such as self-reactive B cells, are induced to express CD95 by CD40 ligand (CD40L) and are subsequently eliminated by CD95 ligand (CD95L) when they present antigen to CD4+ T cells. B cells that bind antigen acutely due to sudden antigen encounter, such as foreign antigen reactive B cells, up-regulate CD95, but are normally protected from CD95L-mediated apoptosis. Here, however, it is shown in vivo that foreign antigen-specific B cells fail to be protected from CD95-dependent elimination in a host that is CD95 deficient, regardless of antigenic challenge. These data indicate that B cell antigen receptor (BCR)-induced protection against CD95L-mediated apoptosis is not absolute but depends upon other micro-environmental factors in vivo. The normal balance between T cell-dependent humoral immunity and tolerance is thus regulated intrinsically by CD95 expression on responding B cells, and extrinsically by CD95-mediated control of CD95L or other molecules in the lymphoid micro-environment.
Publisher: Wiley
Date: 28-09-2007
DOI: 10.1002/9780470515525.CH3
Abstract: The quantity and quality of signals from the B cell antigen receptor (BCR) drives the positive and negative selection of B lymphocytes and establishes the balance of tolerance and immunity. Experiments using immunoglobulin transgenic mice and mutations in key BCR signalling components have given insight into how the antigen receptor is tuned and how thresholds for qualitatively different outcomes are established and maintained. This research also describes how genetic variants can shift the balance between autoimmunity and tolerance.
Publisher: Wiley
Date: 26-09-2019
DOI: 10.1111/IMR.12808
Abstract: The adaptive immune system is tasked with producing antibodies that recognize a wide scope of potential pathogens, including those never before encountered, and concurrently avoiding formation of antibodies binding host tissues. The erse repertoire of antibodies produced by V(D)J recombination inevitably includes autoantibodies that bind to self-antigens, estimated to be as much as 70% of nascent antibodies on immature B cells. Early theoretical models of tolerance hypothesized that such self-reactive clones could not possibly be allowed to survive and mature. However from the first direct view of the fate of nascent B cells carrying a self-binding antibody it was clear that many "forbidden clones" circulate to secondary lymphoid tissues, where they adopt an IgM
Publisher: American Association for the Advancement of Science (AAAS)
Date: 08-03-1991
Abstract: Self-tolerance to a transgene-encoded protein, hen egg lysozyme, was examined in the T and B cell repertoires of a series of lines of transgenic mice that expressed different serum concentrations of soluble lysozyme. T cells were tolerant in all lines in which lysozyme was expressed irrespective of the antigen concentration, whereas B cell tolerance did not occur when the serum lysozyme concentration was less than 1.5 nanograms per milliliter (0.1 nM). Induction of elevated transgene expression could restore B cell tolerance. These findings support the hypothesis that autoimmune disease may in some instances arise through a bypass of T cell tolerance.
Publisher: Wiley
Date: 04-1997
Publisher: Rockefeller University Press
Date: 10-2012
DOI: 10.1084/JEM.20112744
Abstract: Self-tolerance and immunity are actively acquired in parallel through a poorly understood ability of antigen receptors to switch between signaling death or proliferation of antigen-binding lymphocytes in different contexts. It is not known whether this tolerance-immunity switch requires global rewiring of the signaling apparatus or if it can arise from a single molecular change. By introducing in idual CARD11 mutations found in human lymphomas into antigen-activated mature B lymphocytes in mice, we find here that lymphoma-derived CARD11 mutations switch the effect of self-antigen from inducing B cell death into T cell–independent proliferation, Blimp1-mediated plasmablast differentiation, and autoantibody secretion. Our findings demonstrate that regulation of CARD11 signaling is a critical switch governing the decision between death and proliferation in antigen-stimulated mature B cells and that mutations in this switch represent a powerful initiator for aberrant B cell responses in vivo.
Publisher: Springer Science and Business Media LLC
Date: 12-1992
DOI: 10.1007/BF00586279
Publisher: Springer Science and Business Media LLC
Date: 05-1996
DOI: 10.1038/381325A0
Abstract: Elimination of self-reactive B cells must be balanced against the need for B-cell ersity for antibody responses to pathogens. To analyse factors that determine the extent of B-cell negative selection, we crossed CD45-deficient mice with mice carrying immunoglobulin transgenes specific for hen egg lysozyme (HEL). CD45 positively regulates antigen-receptor signalling and CD45-deficient HEL-specific B cells gave diminished signalling in response to HEL. Significantly, few mature CD45-/- B cells accumulated, despite normal immature B-cell production. Circulating HEL autoantigen mediates negative selection of mature CD45+/+ HEL-binding B cells but, in striking contrast, the autoantigen positively selected CD45-/- HEL-binding B cells, promoting their accumulation as long-lived IgD(hi) cells. These findings are consistent with a signal-threshold model for B-cell selection and demonstrate that changes in antigen receptor signalling can cause high-affinity self-reactive B cells to be actively retained instead of eliminated, thus revealing a potential mechanism for inherited susceptibility to autoimmune disease.
Publisher: Rockefeller University Press
Date: 21-01-2013
DOI: 10.1084/JEM.20121458
Abstract: Acquisition of self-tolerance in the thymus requires T cells to discriminate strong versus weak T cell receptor binding by self-peptide–MHC complexes. We find this discrimination is reported by expression of the transcription factor Helios, which is induced during negative selection but decreases during positive selection. Helios and the proapoptotic protein Bim were coinduced in 55% of nascent CCR7− CD4+ CD69+ thymocytes. These were short-lived cells that up-regulated PD-1 and down-regulated CD4 and CD8 during Bim-dependent apoptosis. Helios and Bim were also coinduced at the subsequent CCR7+ CD4+ CD69+ CD8− stage, and this second wave of Bim-dependent negative selection involved 20% of nascent cells. Unlike CCR7− counterparts, Helios+ CCR7+ CD4+ cells mount a concurrent Card11- and c-Rel–dependent activation response that opposes Bim-mediated apoptosis. This “hollow” activation response consists of many NF-κB target genes but lacks key growth mediators like IL-2 and Myc, and the thymocytes were not induced to proliferate. These findings identify Helios as the first marker known to erge during positive and negative selection of thymocytes and reveal the extent, stage, and molecular nature of two distinct waves of clonal deletion in the normal thymus.
Publisher: Springer Science and Business Media LLC
Date: 21-03-2016
DOI: 10.1038/NG.3531
Publisher: Springer Science and Business Media LLC
Date: 24-10-1991
DOI: 10.1038/353765A0
Abstract: The long-standing hypothesis that tolerance to self antigens is mediated by either elimination or functional inactivation (anergy) or self-reactive lymphocytes is now accepted, but little is known about the factors responsible for initiating one process rather than the other. In the B-cell lineage, tolerant self-reactive cells persist in the peripheral lymphoid organs of transgenic mice expressing lysozyme and anti-lysozyme immunoglobulin genes, but are eliminated in similar transgenic mice expressing anti-major histocompatibility complex immunoglobulin genes. By modifying the structure of the lysozyme transgene and the isotype of the anti-lysozyme immunoglobulin genes, we demonstrate here that induction of anergy or deletion is not due to differences in antibody affinity or isotype, but to recognition of monomeric or oligomeric soluble antigen versus highly multivalent membrane-bound antigen. Our findings indicate that the degree of receptor crosslinking can have qualitatively distinct signalling consequences for lymphocyte development.
Publisher: Springer Science and Business Media LLC
Date: 02-06-2015
Publisher: Elsevier BV
Date: 03-1997
DOI: 10.1016/S1074-7613(00)80335-0
Abstract: Transgenic mice were generated to explore the effects on lymphoid development and immune function of constitutive expression of murine B7.2 on B and T cells. The number of B lymphocytes in primary and secondary lymphoid tissues is normal in B7.2 transgenic lines expressing low levels of B7.2 on B cells, but markedly reduced in transgenic lines expressing moderate to high levels of the transgene on B cells. This reduction is not due to an intrinsic abnormality of the transgenic B cells, but is rather the consequence of an elimination by an immune mechanism requiring the engagement of CD28 on T cells. Interestingly, during cognate antigen-specific interaction with T cells in vivo, B7.2 transgenic B cells are not eliminated, but proliferate and differentiate normally. Our findings suggest that, in the absence of high affinity ligand for the TCR, the CD28-B7.2 system participates in the regulation of B cell homeostasis.
Publisher: Wiley
Date: 08-2000
DOI: 10.1034/J.1600-065X.2000.00614.X
Abstract: Self-tolerance is achieved by deleting or regulating self-reactive lymphocytes at a series of cellular checkpoints placed at many points along the developmental pathways to plasma cells and effector T cells. At each checkpoint, what are the molecular pathways that determine whether a lymphocyte remains quiescent, begins iding, differentiates or dies? In splenic B cells, the decision between quiescence, tolerance by anergy, and activation provides a tractable setting to explore these issues by global gene expression profiling on DNA microarrays. Here we discuss the application of microarrays to illuminate a set of cell fate decisions that appear to be determined by summation of numerous small changes in expression of stimulatory and inhibitory genes. Many genes with known or predicted inhibitory functions are highly expressed in naive, quiescent B cells, notably the signal inhibitor SLAP and DNA-binding proteins of the Kruppel family (LKLF, BKLF, GKLF), Tsc-22, GILZ, Id-3, and GADD45. Activation of naive B cells, triggered by acute binding of antigen to the B-cell receptor, involves a rapid decrease in expression of these inhibitory genes. Promitotic genes are induced in parallel, including c myc, LSIRF/IRF4, cyclin D2, Egr-1 and Egr-2, as are the anti-apoptotic gene A1 and genes for the T-cell-attracting chemokines MIP-1alpha and beta. B-cell tolerance through the process of anergy, induced by chronic binding of self antigen, maintains expression of the inhibitory genes found in quiescent B cells and induces an additional set of inhibitory genes. The latter include inhibitors of signaling - CD72, neurogranin, pcp4 - and additional inhibitors of gene expression such as SATB1, MEF2C, TGIF and Nab-2. The effects of tolerance, the immunosuppressive drug FK506 and other modulators of calcium or MAPK signaling allow in idual gene responses to be linked to different signal transduction pathways. The global molecular profiles obtained illustrate how quiescence and anergy are actively maintained in circulating B cells, how these states are switched to clonal expansion and how they could be better emulated by pro-tolerogenic drugs.
Publisher: Wiley
Date: 07-1995
Abstract: The expression and function of IgM and IgD antigen receptors were studied in a series of anti-hen egg lysozymes (HEL) immunoglobulin (Ig)-transgenic mice expressing either IgM alone, IgD alone, or both IgM and IgD. B cell surface expression of IgD was found to be more efficient than that of IgM. Thus antigen receptor density on IgD+, IgM- B cells was twofold higher than on IgM+, IgD- B cells despite the presence of sevenfold lower levels of membrane heavy chain mRNA, and coexpression of IgD with IgM led to almost complete inhibition of surface IgM. In addition, less extensive down-regulation of IgD occurred following exposure to antigen in vitro. When regulation of CD80/CD86 co-stimulatory molecules by surface Ig was examined, up-regulation of the former was initiated at lower antigen concentrations on IgM-, IgD+ compared to IgM+, IgD- B cells. On correcting for antigen receptor density, however, induction of CD80/CD86 by IgM and IgD was comparable. Taken together, these results reinforced the functional similarity of IgM and IgD antigen receptors while at the same time revealing differences in expression which may explain their simultaneous presence on mature B cells.
Publisher: Springer Science and Business Media LLC
Date: 05-1995
DOI: 10.1038/375334A0
Abstract: During an immune response, hypermutation of immunoglobulin genes in B cells proliferating within germinal centres (GCs) generates variant antibodies that react with higher affinity against either foreign or self antigens. Several experiments suggest that self-reactive B cells may be censored at this stage of the immune response, but the rarity of these cells and the dynamic nature of GC reactions have prevented direct analysis. We have developed a new approach to visualize the fate of antigen-specific B cells during GC reactions by seeding an ongoing immune response with lysozyme-specific B cells from immunoglobulin-gene transgenic animals. Administration of soluble antigen at the peak of the GC response rapidly eliminates lysozyme-specific GC B cells in two waves of apoptosis, one within the GC and a second in cells that have redistributed to lymphoid zones that are rich in T cells. Elimination of these cells is inhibited by constitutive expression of the follicular lymphoma proto-oncogene bcl-2. These findings reveal censoring steps that may normally prevent affinity maturation of autoantibodies to systemic autoantigens, and might be used by pathogenic microorganisms or in clinical strategies to interfere with antibody responses.
Publisher: Springer Science and Business Media LLC
Date: 13-07-2009
DOI: 10.1038/NI.1769
Publisher: Public Library of Science (PLoS)
Date: 21-10-2013
Publisher: Springer Science and Business Media LLC
Date: 03-03-2003
DOI: 10.1038/NI906
Publisher: Wiley
Date: 17-03-2015
DOI: 10.1038/ICB.2015.32
Publisher: Wiley
Date: 04-1997
DOI: 10.1111/J.1600-065X.1997.TB00954.X
Abstract: The recent global pandemic was a spillover from the SARS-CoV-2 virus. Viral entry involves the receptor binding domain (RBD) of the viral spike protein interacting with the protease domain (PD) of the cellular receptor, ACE2. We hereby present a comprehensive mutational landscape of the effects of ACE2-PD point mutations on RBD-ACE2 binding using a saturation mutagenesis approach based on microarray-based oligo synthesis and a single-cell screening assay. We observed that changes in glycosylation sites and directly interacting sites of ACE2-PD significantly influenced ACE2-RBD binding. We further engineered an ACE2 decoy receptor with critical point mutations, D30I, L79W, T92N, N322V, and K475F, named C4-1. C4-1 shows a 200-fold increase in neutralization for the SARS-CoV-2 D614G pseudotyped virus compared to wild-type soluble ACE2 and a sevenfold increase in binding affinity to wild-type spike compared to the C-terminal Ig-Fc fused wild-type soluble ACE2. Moreover, C4-1 efficiently neutralized prevalent variants, especially the omicron variant (EC
Publisher: Wiley
Date: 20-03-2007
Abstract: Genetic variants of interleukin 2 (IL-2) and its receptor are associated with murine and human susceptibility to Type 1 diabetes, yet the role of IL-2 in controlling pancreatic islet-reactive T cells is unknown. Here, we develop a model where IL-2 deficiency precipitates a breakdown of self-tolerance and progression to diabetes, and its action upon diabetogenic islet-specific CD4 T cells can be tracked. We find that IL-2 is not required for Aire-dependent thymic clonal deletion of high-avidity diabetogenic clones, but is essential for thymic formation of islet-specific Foxp3-expressing CD4 T cells. The absence of IL-2 results in the expansion of low-avidity Foxp3(-) islet-reactive CD4 T cells. The mechanism by which IL-2 prevents diabetes is therefore through the establishment of a repertoire of islet-reactive Foxp3(+) T cells within the thymus, and limitation of the peripheral activation of low-avidity islet-reactive T cells that normally escape thymic negative selection.
Publisher: Oxford University Press (OUP)
Date: 12-2010
DOI: 10.1534/GENETICS.110.121160
Abstract: Phenovariance may be obscured when genetic mapping is performed using highly ergent strains, and closely similar strains are preferred if adequate marker density can be established. We sequenced the C57BL/10J mouse genome using the Applied Biosystems SOLiD platform and here describe a genome-wide panel of informative markers that permits the mapping of mutations induced on the closely related C57BL/6J background by outcrossing to C57BL/10J, and backcrossing or intercrossing. The panel consists of 127 single nucleotide polymorphisms validated by capillary sequencing: 124 spaced at ∼20-Mb intervals across the 19 autosomes, and three markers on the X chromosome. We determined the genetic relationship between four C57BL-derived substrains and used the panel to map two N-ethyl-N-nitrosourea (ENU)-induced mutations responsible for visible phenotypes in C57BL/6J mice through bulk segregation analysis. Capillary sequencing, with computation of relative chromatogram peak heights, was used to determine the proportion of alleles from each strain at each marker.
Publisher: Oxford University Press (OUP)
Date: 1994
Abstract: Transgenic mice carrying a rearranged Ig gene encoding the H chain of a lysozyme-specific antibody were used to examine the effect of antigen binding affinity on elimination of self-reactive B cells. In H chain transgenic mice, B cells expressed surface IgM and IgD composed of lysozyme-specific H chains and many different possible L chains from endogenous L chain genes. Immunofluorescent staining and flow cytometry revealed a distinct subset comprising approximately 1% of spleen B cells that bound lysozyme with a high affinity comparable with the original lysozyme-specific antibody. Additional subsets accounting for a total of 5-6% of spleen B cells bound lysozyme more weakly, with the weakest requiring 10,000-fold higher concentrations of monomeric hen egg lysozyme to attain 50% receptor saturation. When the various B cell subpopulations were allowed to develop in animals expressing lysozyme as a membrane-bound antigen on autologous cells, both low and high affinity lysozyme-binding B cells were undetectable in peripheral lymphoid organs. These findings demonstrate the efficacy with which low affinity self-reactive B cells can be eliminated in vivo, consistent with the notion that this cellular mechanism accounts for the absence of natural IgM antibodies against self antigens on the surface of blood cells. The data also illustrate the potential use of Ig transgenic mice for analyzing and selecting novel receptor-ligand interactions.
Publisher: Public Library of Science (PLoS)
Date: 23-10-2015
Publisher: Elsevier BV
Date: 07-2003
DOI: 10.1016/S1074-7613(03)00168-7
Abstract: A central issue in understanding the hematolymphoid system is the generation of appropriate mutant alleles in mice to reveal the function of regulatory genes. Here we describe a mouse strain, Plastic, with a point mutation in a zinc finger of Ikaros that disrupts DNA binding but preserves efficient assembly of the full-length protein into higher order complexes. Ikaros(Plastic) homozygosity is embryonically lethal with severe defects in terminal erythrocyte and granulocyte differentiation, excessive macrophage formation, and blocked lymphopoiesis, while heterozygotes display a partial block in lymphocyte differentiation. The contrast with more circumscribed effects of Ikaros alleles that ablate the full-length protein highlights the importance in mammals of generating recessive niche-filling alleles that inactivate function without creating a void in multimolecular assemblies.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 11-2019
DOI: 10.1126/SCIIMMUNOL.AAY6039
Abstract: Characterizing MAIT cell development led to the identification of key regulators that specify MAIT cell fate in the thymus.
Publisher: Wiley
Date: 28-09-2007
DOI: 10.1002/9780470515280.CH13
Abstract: The need to maintain self-tolerance is at odds with the need to draw upon antibody and T cell receptor ersity to fight infection. Advances in genetic manipulation of the mouse have at last brought into view the clonal selection mechanisms that underpin self-tolerance, confirming in general terms the notion of clonal deletion and clonal anergy put forward by Burnet and Nossal. The image that has emerged, however, is much more sophisticated than could have been imagined, revealing that self-reactive clones are deleted or held back in a remarkable series of culling checkpoints placed at many steps along the pathway to antibody production. These checkpoints act in concert to balance the nature and size of the holes in the repertoire generated by self-tolerance against the need to draw upon as many clones as possible for immunity to infection. Spontaneous and induced mutations in the mouse, such as Fas, PTP1C and CD45 mutations, have just begun to yield a few glimpses into the molecular circuitry underpinning these cellular checkpoints. Much more extensive genetic analysis, made possible by the genome project, will be needed to illuminate the details of those circuits and the factors that lead them to fail in autoimmune disease.
Publisher: Springer US
Date: 2001
Publisher: Wiley
Date: 03-05-2018
DOI: 10.1111/IMCB.12047
Abstract: The thymus plays a crucial role in immune tolerance by exposing developing T cells (thymocytes) to a myriad of self-antigens. Strong T-cell receptor (TCR) engagement induces tolerance in self-reactive thymocytes by stimulating apoptosis or selection into specialized T-cell lineages, including intestinal TCRαβ
Publisher: Elsevier BV
Date: 07-1998
DOI: 10.1016/S0960-9822(07)00365-X
Abstract: Lymphocytes are more likely to make an immune response if costimulatory and antigen receptors coincidently signal the way the signals are integrated illustrates how a lymphocyte learns to distinguish self from foreign antigens, and provides a model for coincident signaling through more than one receptor.
Publisher: Rockefeller University Press
Date: 17-10-2011
DOI: 10.1084/JEM.20110345
Abstract: In humans, DOCK8 immunodeficiency syndrome is characterized by severe cutaneous viral infections. Thus, CD8 T cell function may be compromised in the absence of DOCK8. In this study, by analyzing mutant mice and humans, we demonstrate a critical, intrinsic role for DOCK8 in peripheral CD8 T cell survival and function. DOCK8 mutation selectively diminished the abundance of circulating naive CD8 T cells in both species, and in DOCK8-deficient humans, most CD8 T cells displayed an exhausted CD45RA+CCR7− phenotype. Analyses in mice revealed the CD8 T cell abnormalities to be cell autonomous and primarily postthymic. DOCK8 mutant naive CD8 T cells had a shorter lifespan and, upon encounter with antigen on dendritic cells, exhibited poor LFA-1 synaptic polarization and a delay in the first cell ision. Although DOCK8 mutant T cells underwent near-normal primary clonal expansion after primary infection with recombinant influenza virus in vivo, they showed greatly reduced memory cell persistence and recall. These findings highlight a key role for DOCK8 in the survival and function of human and mouse CD8 T cells.
Publisher: Rockefeller University Press
Date: 12-07-2017
DOI: 10.1084/JEM.20161454
Abstract: CD79B and MYD88 mutations are frequently and simultaneously detected in B cell malignancies. It is not known if these mutations cooperate or how crosstalk occurs. Here we analyze the consequences of CD79B and MYD88L265P mutations in idually and combined in normal activated mouse B lymphocytes. CD79B mutations alone increased surface IgM but did not enhance B cell survival, proliferation, or altered NF-κB responsive markers. Conversely, B cells expressing MYD88L265P decreased surface IgM coupled with accumulation of endoglycosidase H–sensitive IgM intracellularly, resembling the trafficking block in anergic B cells repeatedly stimulated by self-antigen. Mutation or overexpression of CD79B counteracted the effect of MYD88L265P. In B cells chronically stimulated by self-antigen, CD79B and MYD88L265P mutations in combination, but not in idually, blocked peripheral deletion and triggered differentiation into autoantibody secreting plasmablasts. These results reveal that CD79B and surface IgM constitute a rate-limiting checkpoint against B cell dysregulation by MYD88L265P and provide an explanation for the co-occurrence of MYD88 and CD79B mutations in lymphomas.
Publisher: Wiley
Date: 09-2009
DOI: 10.1038/ICB.2009.61
Abstract: We report two new mouse strains: Jasmine (C57BL/6J/Apb-Tap2jas/Apb), with a point mutation in the transporter associated with antigen processing (TAP)2 and Rose, (C57BL/6J/Apb-Tap1rose/Apb), with a point mutation in TAP1. These strains were detected as the result of ethyl nitroso urea (ENU) screens for recessive point mutations affecting the immune system. As expected in cases of defective TAP expression, the mice have very low major histocompatibility complex (MHC)-I cell-surface expression, and few CD8(+) T cells. The Rose strain has an A to T substitution in exon 10 of TAP1, resulting in an asparagine to valine substitution at position 643. Jasmine has an A to C transversion in exon 5 of TAP2, resulting in a threonine to proline substitution at position 293 of the protein. The mutation does not affect mRNA levels, but results in a very severe reduction in TAP2 protein. TAP1 protein levels are also decreased in Jasmine mice, demonstrating a new role for mouse TAP2 in stabilizing TAP1 protein expression. Jasmine is the first strain available with defective TAP2. The two mouse strains provide additional animal models for the human condition Bare Lymphocyte syndrome type 1, and identify new residues important for TAP function.
Publisher: Wiley
Date: 2021
DOI: 10.1002/CTI2.1236
Publisher: Springer Science and Business Media LLC
Date: 11-1989
DOI: 10.1038/342385A0
Abstract: In transgenic mice, mature peripheral B lymphocytes in lymphoid follicles, like immature B cells, are rendered tolerant by encounter with self-antigen, provided receptor occupancy by self-antigen exceeds a critical threshold. The tolerant state of the B cell is closely correlated with down-regulation of membrane IgM but not IgD antigen-receptors. Identical changes in antigen-receptor expression occur in a subset of follicular B cells in nontransgenic mice, suggesting that clonally silenced self-reactive cells are common in the peripheral B-cell repertoire.
Publisher: Springer Science and Business Media LLC
Date: 23-02-2018
DOI: 10.1038/S41598-018-21389-8
Abstract: A subset of human follicular helper T cells (TFH) cells expresses CD57 for which no distinct function has been identified. We show that CD57+ TFH cells are universally PD-1 hi , but compared to their CD57− PD-1 hi counterparts, express little IL-21 or IL-10 among others. Instead, CD57 expression on TFH cells marks cytotoxicity transcriptional signatures that translate into only a weak cytotoxic phenotype. Similarly, circulating PD-1+ CD57+ CD4+ T cells make less cytokine than their CD57− PD-1+ counterparts, but have a prominent cytotoxic phenotype. By analysis of responses to STAT3-dependent cytokines and cells from patients with gain- or loss-of-function STAT3 mutations, we show that CD4+ T cell cytotoxicity is STAT3-dependent. TFH formation also requires STAT3, but paradoxically, once formed, PD-1 hi cells become unresponsive to STAT3. These findings suggest that changes in blood and germinal center cytotoxicity might be affected by changes in STAT3 signaling, or modulation of PD-1 by therapy.
Publisher: Rockefeller University Press
Date: 09-04-2007
DOI: 10.1084/JEM.20061923
Abstract: Immunological memory is characterized by heightened immunoglobulin (Ig) G antibody production caused in part by enhanced plasma cell formation conferred by conserved transmembrane and cytoplasmic segments in isotype-switched IgG B cell receptors. We tested the hypothesis that the IgG tail enhances intracellular B cell antigen receptor (BCR) signaling responses to antigen by analyzing B cells from Ig transgenic mice with IgM receptors or chimeric IgMG receptors containing the IgG tail segment. The IgG tail segment enhanced intracellular calcium responses but not tyrosine or extracellular signal–related kinase (ERK) phosphorylation. Biochemical analysis and crosses to CD22-deficient mice established that IgG tail enhancement of calcium and antibody responses, as well as marginal zone B cell formation, was not due to diminished CD22 phosphorylation or inhibitory function. Microarray profiling showed no evidence for enhanced signaling by the IgG tail for calcium/calcineurin, ERK, or nuclear factor κB response genes and little evidence for any enhanced gene induction. Instead, almost half of the antigen-induced gene response in IgM B cells was diminished 50–90% by the IgG tail segment. These findings suggest a novel “less-is-more” hypothesis to explain how switching to IgG enhances B cell memory responses, whereby decreased BCR signaling to genes that oppose marginal zone and plasma cell differentiation enhances the formation of these key cell types.
Publisher: American Society for Clinical Investigation
Date: 06-2009
DOI: 10.1172/JCI32743
Publisher: Public Library of Science (PLoS)
Date: 17-03-2015
Publisher: Rockefeller University Press
Date: 18-10-2004
DOI: 10.1084/JEM.20040581
Abstract: Inactivation of the autoimmune regulator (Aire) gene causes a rare recessive disorder, autoimmune polyendocrine syndrome 1 (APS1), but it is not known if Aire-dependent tolerance mechanisms are susceptible to the quantitative genetic changes thought to underlie more common autoimmune diseases. In mice with a targeted mutation, complete loss of Aire abolished expression of an insulin promoter transgene in thymic epithelium, but had no effect in pancreatic islets or the testes. Loss of one copy of Aire diminished thymic expression of the endogenous insulin gene and the transgene, resulting in a 300% increase in islet-reactive CD4 T cells escaping thymic deletion in T cell receptor transgenic mice, and dramatically increased progression to diabetes. Thymic deletion induced by antigen under control of the thyroglobulin promoter was abolished in Aire homozygotes and less efficient in heterozygotes, providing an explanation for thyroid autoimmunity in APS1. In contrast, Aire deficiency had no effect on thymic deletion to antigen controlled by a systemic H-2K promoter. The sensitivity of Aire-dependent thymic deletion to small reductions in function makes this pathway a prime candidate for more subtle autoimmune quantitative trait loci, and suggests that methods to increase Aire activity would be a potent strategy to lower the incidence of organ-specific autoimmunity.
Publisher: Elsevier BV
Date: 07-2018
Publisher: Elsevier BV
Date: 12-2022
DOI: 10.1016/J.IMMUNI.2022.11.001
Abstract: The association between cancer and autoimmune disease is unexplained, exemplified by T cell large granular lymphocytic leukemia (T-LGL) where gain-of-function (GOF) somatic STAT3 mutations correlate with co-existing autoimmunity. To investigate whether these mutations are the cause or consequence of CD8
Publisher: Elsevier BV
Date: 04-2006
DOI: 10.1016/J.BBRC.2006.02.032
Abstract: The biochemical differences between simple steatosis, a benign liver disease, and non-alcoholic steatohepatitis, which leads to cirrhosis, are unclear. Fat aussie is an obese mouse strain with a truncating mutation (foz) in the Alms1 gene. Chow-fed female foz/foz mice develop obesity, diabetes, and simple steatosis. We fed foz/foz and wildtype mice a high-fat diet. Foz/foz mice developed serum ALT elevation and severe steatohepatitis with hepatocyte ballooning, inflammation, and fibrosis wildtype mice showed simple steatosis. Biochemical pathways favoring hepatocellular lipid accumulation (fatty acid uptake lipogenesis) and lipid disposal (fatty acid beta-oxidation triglyceride egress) were both induced by high-fat feeding in wildtype but not foz/foz mice. The resulting extremely high hepatic triglyceride levels were associated with induction of mitochondrial uncoupling protein-2 and adipocyte-specific fatty acid binding protein-2, but not cytochrome P4502e1 or lipid peroxidation. In this model of metabolic syndrome, transition of steatosis to steatohepatitis was associated with hypoadiponectinemia, a mediator of hepatic fatty acid disposal pathways.
Publisher: The American Association of Immunologists
Date: 06-2012
Abstract: Activated Th cells influence other T cells via positive feedback circuits that expand and polarize particular types of response, but little is known about how they may also initiate negative feedback against immunopathological reactions. In this study, we demonstrate the emergence, during chronic inflammation, of GATA-3+ Th2 inhibitory (Th2i) cells that express high levels of inhibitory proteins including IL-10, CTLA-4, and granzyme B, but do so independently of Foxp3. Whereas other Th2 effectors promote proliferation and IL-4 production by naive T cells, Th2i cells suppress proliferation and IL-4 production. We show that Th2i cells develop directly from Th2 effectors, in a manner that can be promoted by effector cytokines including IL-2, IL-10, and IL-21 ex vivo and that requires T cell activation through CD28, Card11, and IL-2 in vivo. Formation of Th2i cells may act as an inbuilt activation-induced feedback inhibition mechanism against excessive or chronic Th2 responses.
Publisher: Rockefeller University Press
Date: 28-10-2002
DOI: 10.1084/JEM.20020735
Abstract: Type 1 diabetes and other organ-specific autoimmune diseases often cluster together in human families and in congenic strains of NOD (nonobese diabetic) mice, but the inherited immunoregulatory defects responsible for these diseases are unknown. Here we track the fate of high avidity CD4 T cells recognizing a self-antigen expressed in pancreatic islet β cells using a transgenic mouse model. T cells of identical specificity, recognizing a dominant peptide from the same islet antigen and major histocompatibility complex (MHC)-presenting molecule, were followed on autoimmune susceptible and resistant genetic backgrounds. We show that non-MHC genes from the NOD strain cause a failure to delete these high avidity autoreactive T cells during their development in the thymus, with subsequent spontaneous breakdown of CD4 cell tolerance to the islet antigen, formation of intra-islet germinal centers, and high titre immunoglobulin G1 autoantibody production. In mixed bone marrow chimeric animals, defective thymic deletion was intrinsic to T cells carrying diabetes susceptibility genes. These results demonstrate a primary failure to censor forbidden clones of self-reactive T cells in inherited susceptibility to organ-specific autoimmune disease, and highlight the importance of thymic mechanisms of tolerance in organ-specific tolerance.
Publisher: Elsevier BV
Date: 12-2008
Publisher: Public Library of Science (PLoS)
Date: 31-01-2013
Publisher: Springer Berlin Heidelberg
Date: 1999
Publisher: Wiley
Date: 02-1994
DOI: 10.1002/J.1460-2075.1994.TB06324.X
Abstract: To explore the biochemical basis for maintaining immunological tolerance by functional inactivation of self-reactive B lymphocytes, transgenic mice carrying rearranged anti-lysozyme immunoglobulin transgenes and a lysozyme transgene were used as a source of large numbers of tolerant self-reactive B cells. Antigen receptors of the IgD isotype were expressed at normal levels on tolerant B cells, contained the heterodimeric MB1/B29 signalling component of the receptor complex and were structurally indistinguishable from IgD on nontolerant B cells. In contrast, cell surface expression of IgM receptor complexes on tolerant B cells was greatly reduced, despite normal expression of mRNA encoding the receptor components. Three-fold fewer immunoreactive mu heavy chains were detectable after a short period of biosynthetic labelling and the immunoreactive mu chains produced were paired with kappa light chains and assembled normally into intact receptor complexes containing the MB1/B29 heterodimer. Nascent IgM receptor complexes nevertheless failed to be processed into an endoglycosidase H-resistant form in the tolerant B cells and thus appeared to be selectively blocked in their transport from the endoplasmic reticulum to the medial Golgi. These findings demonstrate that intracellular trafficking of antigen receptor complexes is regulated by exposure to receptor stimuli at the cell surface causing a long-lasting decrease in surface receptor expression on tolerant B cells.
Publisher: Wiley
Date: 28-03-2006
DOI: 10.1111/J.0105-2896.2006.00363.X
Abstract: T-cell development is perhaps one of the best understood processes of mammalian cell differentiation, as many of the genes and pathways have been identified. By contrast, relatively little is known about the genes and pathways involved in immunological tolerance to self-antigens. Here, we describe the challenges associated with a genomewide screen designed at identifying new immune regulatory genes that uses a model of organ-specific autoimmunity leading to type 1 diabetes. The successful propagation and identification of the new gene variants will shed light on the various developmental checkpoints in lymphocyte development that are crucial for establishing tolerance to self-antigens.
Publisher: Elsevier BV
Date: 07-2007
Publisher: Public Library of Science (PLoS)
Date: 23-11-2015
Publisher: Wiley
Date: 05-04-2016
DOI: 10.1038/ICB.2016.27
Abstract: Linkage analysis studies for autoimmune diabetes have revealed multiple non-major histocompatibility complex (MHC) chromosomal regions linked to disease susceptibility. To date, more than 20 insulin-dependent diabetes (Idd) loci linked to diabetes susceptibility have been identified in NOD mice and validated via congenic breeding. Importantly, evidence suggests that Idd loci may regulate at least two pathological steps during autoimmune diabetes development, namely the onset of insulitis and the transition from insulitis to overt diabetes. Here we assess the role of various non-MHC Idd diabetes-resistance loci, which have been validated in the non-transgenic setting, on autoimmune diabetes progression in the transgenic setting. Specifically, we generated multiple Idd congenic strains in the 3A9-TCR:insHEL NOD.H2(k) transgenic model and monitored their diabetes incidence. We show that 3A9-TCR:insHEL NOD.H2(k) mice congenic for Idd3 or Idd5 display a reduction in diabetes development, whereas mice congenic for Idd9 or Idd13 exhibit an increase, in comparison with 3A9-TCR:insHEL NOD.H2(k) mice. These results suggest that the presence of the 3A9-TCR and hen egg lysosyme transgenes can offset the regulatory function of certain diabetes-resistance genetic variants contained within the Idd loci, including Idd9 and Idd13. We propose the antigen-specific 3A9-TCR:insHEL transgenic model as a useful tool for the study of the genetics of autoimmune diabetes development.
Publisher: Springer Science and Business Media LLC
Date: 08-1991
DOI: 10.1038/352532A0
Abstract: Production of autoantibodies, which characterizes most autoimmune diseases, is normally avoided by active elimination or functional inactivation (anergy) of B and T lymphocytes bearing receptors for self antigens. The mechanisms leading to the escape of self-reactive clones from these normal tolerance mechanisms in autoimmune diseases nevertheless remain obscure. Here, we demonstrate that clonal anergy in B lymphocytes is a reversible process, and that silenced self-reactive B cells can be reactivated under particular conditions to give rise to vigorous antibody responses. Reactivation of anergic lymphocytes may explain many ex les of transient autoimmune reactions in normal in iduals, and may under pathological conditions be important in the development of chronic autoimmune disease.
Publisher: American Society of Hematology
Date: 10-2015
DOI: 10.1182/BLOOD-2015-03-631374
Abstract: Functional reversion of a germline CARD11 mutation in T cells is associated with the development of Omenn syndrome. Defective thymic T-cell development and peripheral lymphopenia are no prerequisite for the development of Omenn syndrome.
Publisher: Springer Science and Business Media LLC
Date: 10-1985
DOI: 10.1038/317430A0
Abstract: The immune system of higher organisms is composed largely of two distinct cell types, B lymphocytes and T lymphocytes, each of which is independently capable of recognizing an enormous number of distinct entities through their antigen receptors surface immunoglobulin in the case of the former, and the T-cell receptor (TCR) in the case of the latter. In both cell types, the genes encoding the antigen receptors consist of multiple gene segments which recombine during maturation to produce many possible peptides. One striking difference between B- and T-cell recognition that has not yet been resolved by the structural data is the fact that T cells generally require a major histocompatibility determinant together with an antigen whereas, in most cases, antibodies recognize antigen alone. Recently, we and others have found that a series of TCR V beta gene sequences show conservation of many of the same residues that are conserved between heavy- and light-chain immunoglobulin V regions, and these V beta sequences are predicted to have an immunoglobulin-like secondary structure. To extend these studies, we have isolated and sequenced eight additional alpha-chain complementary cDNA clones and compared them with published sequences. Analyses of these sequences, reported here, indicate that V alpha regions have many of the characteristics of V beta gene segments but differ in that they almost always occur as cross-hybridizing gene families. We conclude that there may be very different selective pressures operating on V alpha and V beta sequences and that the V alpha repertoire may be considerably larger than that of V beta.
Publisher: Rockefeller University Press
Date: 03-09-2001
Publisher: American Association for the Advancement of Science (AAAS)
Date: 24-04-1998
DOI: 10.1126/SCIENCE.280.5363.582
Abstract: Affinity-driven selection of B lymphocytes within germinal centers is critical for the development of high-affinity memory cells and host protection. To investigate the role of the CD21/CD35 coreceptor in B cell competition for follicular retention and survival within the germinal center, either Cr2 + or Cr2 null lysozyme-specific transgenic B cells were adoptively transferred into normal mice immunized with duck (DEL) or turkey (TEL) lysozyme, which bind with different affinities. In mice injected with high-affinity turkey lysozyme, Cr2 null B cells responded by follicular retention however, they could not survive within germinal centers. This suggests that CD21 provides a signal independent of antigen that is required for survival of B cells in the germinal center.
Publisher: Rockefeller University Press
Date: 18-05-1998
Abstract: Antigen-specific B cells are implicated as antigen-presenting cells in memory and tolerance responses because they capture antigens efficiently and localize to T cell zones after antigen capture. It has not been possible, however, to visualize the effect of specific B cells on specific CD4+ helper T cells under physiological conditions. We demonstrate here that rare T cells are activated in vivo by minute quantities of antigen captured by antigen-specific B cells. Antigen-activated B cells are helped under these conditions, whereas antigen-tolerant B cells are killed. The T cells proliferate and then disappear regardless of whether the B cells are activated or tolerant. We show genetically that T cell activation, proliferation, and disappearance can be mediated either by transfer of antigen from antigen-specific B cells to endogenous antigen-presenting cells or by direct B–T cell interactions. These results identify a novel antigen presentation route, and demonstrate that B cell presentation of antigen has profound effects on T cell fate that could not be predicted from in vitro studies.
Publisher: Elsevier BV
Date: 03-2010
Publisher: Springer Science and Business Media LLC
Date: 10-11-2016
DOI: 10.1038/NCOMMS13381
Abstract: Self-tolerance by clonal anergy of B cells is marked by an increase in IgD and decrease in IgM antigen receptor surface expression, yet the function of IgD on anergic cells is obscure. Here we define the RNA landscape of the in vivo anergy response, comprising 220 induced sequences including a core set of 97. Failure to co-express IgD with IgM decreases overall expression of receptors for self-antigen, but paradoxically increases the core anergy response, exemplified by increased Sdc1 encoding the cell surface marker syndecan-1. IgD expressed on its own is nevertheless competent to induce calcium signalling and the core anergy mRNA response. Syndecan-1 induction correlates with reduction of surface IgM and is exaggerated without surface IgD in many transitional and mature B cells. These results show that IgD attenuates the response to self-antigen in anergic cells and promotes their accumulation. In this way, IgD minimizes tolerance-induced holes in the pre-immune antibody repertoire.
Publisher: Springer Science and Business Media LLC
Date: 07-1997
DOI: 10.1038/40912
Publisher: Springer Science and Business Media LLC
Date: 11-05-2003
DOI: 10.1038/NI924
No related grants have been discovered for Christopher Goodnow.