ORCID Profile
0000-0001-6771-8891
Current Organisation
Yonsei University College of Medicine
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Biochemistry and Cell Biology | Receptors and Membrane Biology | Cellular Immunology | Protein Trafficking | Proteomics and Intermolecular Interactions (excl. Medical Proteomics) | Innate Immunity | Biological And Medical Chemistry | Biochemistry and Cell Biology not elsewhere classified | Infectious Agents | Enzymes | Nanomedicine | Medical Biochemistry: Proteins And Peptides | Immunology | Nanotechnology | Organic Chemistry not elsewhere classified | Enzymes | Humoural Immunology and Immunochemistry | Medical Infection Agents (incl. Prions) | Nanobiotechnology
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Biological Sciences | Expanding Knowledge in the Chemical Sciences | Immune System and Allergy | Infectious Diseases | Wheat | Biological sciences | Expanding Knowledge in Technology | Diagnostics | Treatments (e.g. chemicals, antibiotics) |
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Publications
Differential expression of pathogen-recognition molecules between dendritic cell subsets revealed by plasma membrane proteomic analysis
Publisher: Elsevier BV
Date: 05-2010
DOI: 10.1016/J.MOLIMM.2010.02.028
Abstract: Dendritic cells (DC) are comprised of several subsets with distinct functions, differing in their capacity to respond to pathogen products. To gain novel insights into their pathogen specificity, we compared the protein composition of the plasma membrane of CD8+ and CD8- DC, directly isolated from mouse spleens. Differences in protein expression were determined using semi-quantitative high-resolution mass spectrometry of label-free plasma membrane-enriched fractions. Our comparative proteomic analysis detected over 1500 proteins, revealing broad differences in expression of pathogen receptors, adhesion molecules and T-cell regulatory molecules. Many of these findings were validated using flow cytometry and Western Blot analysis of integral and luminal surface-associated membrane proteins. This analysis provides major advantages over genomic approaches as it directly measures protein expression at a particular location. Our study highlights the ersity of surface protein expression amongst components of the DC network.
No driving without a license
Publisher: Springer Science and Business Media LLC
Date: 02-2005
DOI: 10.1038/NI0205-125
Differential use of autophagy by primary dendritic cells specialized in cross-presentation
Publisher: Informa UK Limited
Date: 07-05-2015
Differential antigenic requirements by diverse MR1‐restricted T cells
Publisher: Wiley
Date: 13-01-2022
DOI: 10.1111/IMCB.12519
Abstract: MHC‐related protein 1 (MR1) presents microbial riboflavin metabolites to mucosal‐associated invariant T (MAIT) cells for surveillance of microbial presence. MAIT cells express a semi‐invariant T‐cell receptor (TCR), which recognizes MR1–antigen complexes in a pattern‐recognition‐like manner. Recently, erse populations of MR1‐restricted T cells have been described that exhibit broad recognition of tumor cells and appear to recognize MR1 in association with tumor‐derived self‐antigens, though the identity of these antigens remains unclear. Here, we have used TCR gene transfer and engineered MR1‐expressing antigen‐presenting cells to probe the MR1 restriction and antigen reactivity of a range of MR1‐restricted TCRs, including model tumor‐reactive TCRs. We confirm MR1 reactivity by these TCRs, show differential dependence on lysine at position 43 of MR1 (K43) and demonstrate competitive inhibition by the MR1 ligand 6‐formylpterin. TCR‐expressing reporter lines, however, failed to recapitulate the robust tumor specificity previously reported, suggesting an importance of accessory molecules for MR1‐dependent tumor reactivity. Finally, MR1‐mutant cell lines showed that distinct residues on the α1/α2 helices were required for TCR binding by different MR1‐restricted T cells and suggested central but distinct docking modes by the broad family of MR1‐restricted αβ TCRs. Collectively, these data are consistent with recognition of distinct antigens by erse MR1‐restricted T cells.
Putative IKDCs are functionally and developmentally similar to natural killer cells, but not to dendritic cells
Publisher: Rockefeller University Press
Date: 08-10-2007
DOI: 10.1084/JEM.20071351
Abstract: Interferon-producing killer dendritic cells (IKDCs) have been described as possessing the lytic potential of NK cells and the antigen-presenting capacity of dendritic cells (DCs). In this study, we examine the lytic function and antigen-presenting capacity of mouse spleen IKDCs, including those found in DC preparations. IKDCs efficiently killed NK cell targets, without requiring additional activation stimuli. However, in our hands, when exposed to protein antigen or to MHC class II peptide, IKDCs induced little or no T cell proliferation relative to conventional DCs or plasmacytoid DCs, either before or after activation with CpG, or in several disease models. Certain developmental features indicated that IKDCs resembled NK cells more than DCs. IKDCs, like NK cells, did not express the transcription factor PU.1 and were absent from recombinase activating gene-2–null, common γ-chain–null (Rag2−/−Il2rg−/−) mice. When cultured with IL-15 and -18, IKDCs proliferated extensively, like NK cells. Under these conditions, a proportion of expanded IKDCs and NK cells expressed high levels of surface MHC class II. However, even such MHC class II+ IKDCs and NK cells induced poor T cell proliferative responses compared with DCs. Thus, IKDCs resemble NK cells functionally, and neither cell type could be induced to be effective antigen-presenting cells.
MHC Class II Expression Is Regulated in Dendritic Cells Independently of Invariant Chain Degradation
Publisher: Elsevier BV
Date: 06-2001
DOI: 10.1016/S1074-7613(01)00148-0
Abstract: We have investigated the mechanisms that control MHC class II (MHC II) expression in immature and activated dendritic cells (DC) grown from spleen and bone marrow precursors. Degradation of the MHC II chaperone invariant chain (Ii), acquisition of peptide cargo by MHC II, and delivery of MHC II-peptide complexes to the cell surface proceeded similarly in both immature and activated DC. However, immature DC reendocytosed and then degraded the MHC II-peptide complexes much faster than the activated DC. MHC II expression in DC is therefore not controlled by the activity of the protease(s) that degrade Ii, but by the rate of endocytosis of peptide-loaded MHC II. Late after activation, DC downregulated MHC II synthesis both in vitro and in vivo.
Migratory Dendritic Cells Transfer Antigen to a Lymph Node-Resident Dendritic Cell Population for Efficient CTL Priming
Publisher: Elsevier BV
Date: 07-2006
DOI: 10.1016/J.IMMUNI.2006.04.017
Abstract: Skin dendritic cells (DCs) are thought to act as key initiators of local T cell immunity. Here we show that after skin infection with herpes simplex virus (HSV), cytotoxic T lymphocyte (CTL) activation required MHC class I-restricted presentation by nonmigratory CD8(+) DCs rather than skin-derived DCs. Despite a lack of direct presentation by migratory DCs, blocking their egress from infected skin substantially inhibited class I-restricted presentation and HSV-specific CTL responses. These results support the argument for initial transport of antigen by migrating DCs, followed by its transfer to the lymphoid-resident DCs for presentation and CTL priming. Given that relatively robust CTL responses were seen with small numbers of skin-emigrant DCs, we propose that this inter-DC antigen transfer functions to lify presentation across a larger network of lymphoid-resident DCs for efficient T cell activation.
Dendritic Cell Migration and Antigen Presentation Are Coordinated by the Opposing Functions of the Tetraspanins CD82 and CD37
Publisher: The American Association of Immunologists
Date: 02-2016
Abstract: This study supports a new concept where the opposing functions of the tetraspanins CD37 and CD82 may coordinate changes in migration and Ag presentation during dendritic cell (DC) activation. We have previously published that CD37 is downregulated upon monocyte-derived DC activation, promotes migration of both skin and bone marrow–derived dendritic cells (BMDCs), and restrains Ag presentation in splenic and BMDCs. In this article, we show that CD82, the closest phylogenetic relative to CD37, appears to have opposing functions. CD82 is upregulated upon activation of BMDCs and monocyte-derived DCs, restrains migration of skin and BMDCs, supports MHC class II maturation, and promotes stable interactions between T cells and splenic DCs or BMDCs. The underlying mechanism involves the rearrangement of the cytoskeleton via a differential activation of small GTPases. Both CD37−/− and CD82−/− BMDCs lack cellular projections, but where CD37−/− BMDCs spread poorly on fibronectin, CD82−/− BMDCs are large and spread to a greater extent than wild-type BMDCs. At the molecular level, CD82 is a negative regulator of RhoA, whereas CD37 promotes activation of Rac-1 both tetraspanins negatively regulate Cdc42. Thus, this study identifies a key aspect of DC biology: an unactivated BMDC is CD37hiCD82lo, resulting in a highly motile cell with a limited ability to activate naive T cells. By contrast, a late activated BMDC is CD37loCD82hi, and thus has modified its migratory, cytoskeletal, and Ag presentation machinery to become a cell superbly adapted to activating naive T cells.
Downregulation of MHC class I expression by influenza A and B viruses
Publisher: Frontiers Media SA
Date: 29-05-2019
Resident and Monocyte-Derived Dendritic Cells Become Dominant IL-12 Producers under Different Conditions and Signaling Pathways
Publisher: The American Association of Immunologists
Date: 15-08-2010
Abstract: IL-12 is such a pivotal cytokine that it has been called the third signal for T cell activation, TCR engagement being the first and costimulation being the second. It has been generally viewed that the resident CD8+ dendritic cell (DC) subset is the predominant IL-12–producing cell type. In this study, we found, although this is so under steady state conditions, under inflammatory conditions monocyte-derived DC (mDC) became a major cell type producing IL-12. Depletion of either type of DC resulted in reduced production of IL-12 in vivo. For CD8+ DC, IL-12 production could be stimulated by various pathways viz. signaling through MyD88, Trif, or nucleotide-binding oligomerization domain (Nod)-like receptors. In contrast, for mDC, IL-12 production was mainly dependent on MyD88 signaling. Thus, conventional DCs and mDCs use different pathways to regulate IL-12 production.
The Molecular Signature of Tissue Resident Memory CD8 T Cells Isolated from the Brain
Publisher: The American Association of Immunologists
Date: 10-2012
Abstract: Tissue resident memory (Trm) CD8 T cells represent a newly described memory T cell population. We have previously characterized a population of Trm cells that persists within the brain after acute virus infection. Although capable of providing marked protection against a subsequent local challenge, brain Trm cells do not undergo recall expansion after dissociation from the tissue. Furthermore, these Trm cells do not depend on the same survival factors as the circulating memory T cell pool as assessed either in vivo or in vitro. To gain greater insight into this population of cells, we compared the gene expression profiles of Trm cells isolated from the brain with those of circulating memory T cells isolated from the spleen after an acute virus infection. Trm cells displayed altered expression of genes involved in chemotaxis, expressed a distinct set of transcription factors, and overexpressed several inhibitory receptors. Cumulatively, these data indicate that Trm cells are a distinct memory T cell population disconnected from the circulating memory T cell pool and display a unique molecular signature that likely results in optimal survival and function within their local environment.
Transfusion-Related Renal Dysfunction After Cardiac Surgery
Publisher: Elsevier BV
Date: 07-2022
MHC Class II Ubiquitination Regulates Dendritic Cell Function and Immunity
Publisher: The American Association of Immunologists
Date: 11-2021
Abstract: MHC class II (MHC II) Ag presentation by dendritic cells (DCs) is critical for CD4+ T cell immunity. Cell surface levels of MHC II loaded with peptide is controlled by ubiquitination. In this study, we have examined how MHC II ubiquitination impacts immunity using MHC IIKRKI/KI mice expressing mutant MHC II molecules that are unable to be ubiquitinated. Numbers of conventional DC (cDC) 1, cDC2 and plasmacytoid DCs were significantly reduced in MHC IIKRKI/KI spleen, with the remaining MHC IIKRKI/KI DCs expressing an altered surface phenotype. Whereas Ag uptake, endosomal pH, and cathepsin protease activity were unaltered, MHC IIKRKI/KI cDC1 produced increased inflammatory cytokines and possessed defects in Ag proteolysis. Immunization of MHC IIKRKI/KI mice identified impairments in MHC II and MHC class I presentation of soluble, cell-associated and/or DC-targeted OVA via mAb specific for DC surface receptor Clec9A (anti-Clec9A-OVA mAb). Reduced T cell responses and impaired CTL killing was observed in MHC IIKRKI/KI mice following immunization with cell-associated and anti-Clec9A-OVA. Immunization of MHC IIKRKI/KI mice failed to elicit follicular Th cell responses and generated barely detectable Ab to anti-Clec9A mAb-targeted Ag. In summary, MHC II ubiquitination in DCs impacts the homeostasis, phenotype, cytokine production, and Ag proteolysis by DCs with consequences for Ag presentation and T cell and Ab-mediated immunity.
MR1: a multi-faceted metabolite sensor for T cell activation
Publisher: Elsevier BV
Date: 06-2020
DOI: 10.1016/J.COI.2020.05.006
Abstract: The major histocompatibility complex class I-related molecule MR1 captures and presents small metabolites to MR1-restricted T cells including Mucosal Associated Invariant T (MAIT) cells. The first MR1 ligands discovered were intermediates of microbial riboflavin synthesis, antigens presented to alert inflammatory MAIT cells to bacterial infection. Recent advances have expanded the range of MR1 ligands to include extracellular metabolites released by the commensal microbiome, and yet undefined antigens presented by cancer cells to mediate MR1-dependent anti-tumor activity. MR1 thus exhibits a multifaceted ability to display a erse range of ligands for immune surveillance in a variety of contexts. The mechanisms of antigen presentation by MR1 are of central importance to understanding metabolite-mediated immune homeostasis, immunity to infection and tumor surveillance.
Absence of mucosal-associated invariant T cells in a person with a homozygous point mutation in MR1
Publisher: American Association for the Advancement of Science (AAAS)
Date: 03-07-2020
DOI: 10.1126/SCIIMMUNOL.ABC9492
Abstract: A rare human allele renders MR1 unable to present microbially derived antigen, resulting in a selective loss of MAIT cells.
Reply to: “Differential expression of serpins may selectively license distinct granzyme B functions including antigen cross-presentation”
Publisher: Elsevier BV
Date: 07-2017
Alveolar macrophages are epigenetically altered after inflammation, leading to long-term lung immunoparalysis
Publisher: Springer Science and Business Media LLC
Date: 18-05-2020
DOI: 10.1038/S41590-020-0673-X
Abstract: Sepsis and trauma cause inflammation and elevated susceptibility to hospital-acquired pneumonia. As phagocytosis by macrophages plays a critical role in the control of bacteria, we investigated the phagocytic activity of macrophages after resolution of inflammation. After resolution of primary pneumonia, murine alveolar macrophages (AMs) exhibited poor phagocytic capacity for several weeks. These paralyzed AMs developed from resident AMs that underwent an epigenetic program of tolerogenic training. Such adaptation was not induced by direct encounter of the pathogen but by secondary immunosuppressive signals established locally upon resolution of primary infection. Signal-regulatory protein α (SIRPα) played a critical role in the establishment of the microenvironment that induced tolerogenic training. In humans with systemic inflammation, AMs and also circulating monocytes still displayed alterations consistent with reprogramming six months after resolution of inflammation. Antibody blockade of SIRPα restored phagocytosis in monocytes of critically ill patients in vitro, which suggests a potential strategy to prevent hospital-acquired pneumonia.
A Natural Peptide Antigen within the Plasmodium Ribosomal Protein RPL6 Confers Liver TRM Cell-Mediated Immunity against Malaria in Mice
Publisher: Elsevier BV
Date: 06-2020
Blood-stage Plasmodium infection induces CD8+ T lymphocytes to parasite-expressed antigens, largely regulated by CD8α+ dendritic cells
Publisher: Proceedings of the National Academy of Sciences
Date: 23-09-2008
Abstract: Although CD8 + T cells do not contribute to protection against the blood stage of Plasmodium infection, there is mounting evidence that they are principal mediators of murine experimental cerebral malaria (ECM). At present, there is no direct evidence that the CD8 + T cells mediating ECM are parasite-specific or, for that matter, whether parasite-specific CD8 + T cells are generated in response to blood-stage infection. To resolve this and to define the cellular requirements for such priming, we generated transgenic P. berghei parasites expressing model T cell epitopes. This approach was necessary as MHC class I-restricted antigens to blood-stage infection have not been defined. Here, we show that blood-stage infection leads to parasite-specific CD8 + and CD4 + T cell responses. Furthermore, we show that P. berghei -expressed antigens are cross-presented by the CD8α + subset of dendritic cells (DC), and that this induces pathogen-specific cytotoxic T lymphocytes (CTL) capable of lysing cells presenting antigens expressed by blood-stage parasites. Finally, using three different experimental approaches, we provide evidence that CTL specific for parasite-expressed antigens contribute to ECM.
Cognate CD4+ T cell licensing of dendritic cells in CD8+ T cell immunity
Publisher: Springer Science and Business Media LLC
Date: 10-10-2004
DOI: 10.1038/NI1129
Abstract: Several studies have indicated that CD8(+) T cells require CD4(+) T cell help for memory formation. Evidence suggests that such help can be antigen independent, challenging whether the 'licensing' of dendritic cells (DCs) by CD4(+) T cells is ever required for cytotoxic T lymphocyte (CTL) responses. We show here that help is essential for the generation of CTL immunity to herpes simplex virus 1 and that CD4(+) T cells mediate help in a cognate, antigen-specific way. We provide direct in vivo evidence for DC licensing by helper T cells and show that licensing is rapid and essential for the formation of effector and memory CTLs. In situations in which DCs are poorly licensed by pathogen-derived signals, our findings suggest that CTL immunity may be heavily dependent on cognate DC licensing.
Ubiquitin ligase MARCH 8 cooperates with CD83 to control surface MHC II expression in thymic epithelium and CD4 T cell selection
Publisher: Rockefeller University Press
Date: 08-08-2016
DOI: 10.1084/JEM.20160312
Abstract: Major histocompatibility complex class II (MHC II) expression is tightly regulated, being subjected to cell type–specific mechanisms that closely control its levels at the cell surface. Ubiquitination by the E3 ubiquitin ligase MARCH 1 regulates MHC II expression in dendritic cells and B cells. In this study, we demonstrate that the related ligase MARCH 8 is responsible for regulating surface MHC II in thymic epithelial cells (TECs). March8−/− mice have elevated MHC II at the surface of cortical TECs and autoimmune regulator (AIRE)− medullary TECs (mTECs), but not AIRE+ mTECs. Despite this, thymic and splenic CD4+ T cell numbers and repertoires remained unaltered in March8−/− mice. Notably, the ubiquitination of MHC II by MARCH 8 is controlled by CD83. Mice expressing a mutated form of CD83 (Cd83anu/anu mice) have impaired CD4+ T cell selection, but deleting March8 in Cd83anu/anu mice restored CD4+ T cell selection to normal levels. Therefore, orchestrated regulation of MHC II surface expression in TECs by MARCH 8 and CD83 plays a major role in CD4+ T cell selection. Our results also highlight the specialized use of ubiquitinating machinery in distinct antigen-presenting cell types, with important functional consequences and implications for therapeutic manipulation.
The dominant role of CD8+dendritic cells in cross-presentation is not dictated by antigen capture
Publisher: Proceedings of the National Academy of Sciences
Date: 11-07-2006
Abstract: Mouse spleens contain three populations of conventional (CD11c high ) dendritic cells (DCs) that play distinct functions. The CD8 + DC are unique in that they can present exogenous antigens on their MHC class I molecules, a process known as cross-presentation. It is unclear whether this special ability is because only the CD8 + DC can capture the antigens used in cross-presentation assays, or because this is the only DC population that possesses specialized machinery for cross-presentation. To solve this important question we examined the splenic DC subsets for their ability to both present via MHC class II molecules and cross-present via MHC class I using four different forms of the model antigen ovalbumin (OVA). These forms include a cell-associated form, a soluble form, OVA expressed in bacteria, or OVA bound to latex beads. With the exception of bacterial antigen, which was poorly cross-presented by all DC, all antigenic forms were cross-presented much more efficiently by the CD8 + DC. This pattern could not be attributed simply to a difference in antigen capture because all DC subsets presented the antigen via MHC class II. Indeed, direct assessments of endocytosis showed that CD8 + and CD8 − DC captured comparable amounts of soluble and bead-associated antigen, yet only the CD8 + DC cross-presented these antigenic forms. Our results indicate that cross-presentation requires specialized machinery that is expressed by CD8 + DC but largely absent from CD8 − DC. This conclusion has important implications for the design of vaccination strategies based on antigen targeting to DC.
Local Modulation of Antigen-Presenting Cell Development after Resolution of Pneumonia Induces Long-Term Susceptibility to Secondary Infections
Publisher: Elsevier BV
Date: 07-2017
DOI: 10.1016/J.IMMUNI.2017.06.021
Abstract: Lung infections cause prolonged immune alterations and elevated susceptibility to secondary pneumonia. We found that, after resolution of primary viral or bacterial pneumonia, dendritic cells (DC), and macrophages exhibited poor antigen-presentation capacity and secretion of immunogenic cytokines. Development of these "paralyzed" DCs and macrophages depended on the immunosuppressive microenvironment established upon resolution of primary infection, which involved regulatory T (Treg) cells and the cytokine TGF-β. Paralyzed DCs secreted TGF-β and induced local Treg cell accumulation. They also expressed lower amounts of IRF4, a transcription factor associated with increased antigen-presentation capacity, and higher amounts of Blimp1, a transcription factor associated with tolerogenic functions, than DCs present during primary infection. Blimp1 expression in DC of humans suffering sepsis or trauma correlated with severity and complicated outcomes. Our findings describe mechanisms underlying sepsis- and trauma-induced immunosuppression, reveal prognostic markers of susceptibility to secondary infections and identify potential targets for therapeutic intervention.
MARCH1-mediated ubiquitination of MHC II impacts the MHC I antigen presentation pathway
Publisher: Public Library of Science (PLoS)
Date: 12-07-2018
Life cycle, migration and antigen presenting functions of spleen and lymph node dendritic cells: Limitations of the Langerhans cells paradigm
Publisher: Elsevier BV
Date: 08-2005
DOI: 10.1016/J.SMIM.2005.05.015
Abstract: The phenotypic and functional studies carried out in recent years on dendritic cells (DC) purified from spleen and lymph nodes has revealed the existence of heterogeneous populations with distinct life cycles, migratory properties and antigen presenting functions. A major sub ision can be made between "tissue derived" DC that migrate to the lymph nodes from peripheral tissues, both in the steady state and in the course of infections, and "blood-derived" DC, which reside in the spleen and lymph nodes throughout their life cycle. These two groups of DC can be sub ided into smaller subsets. The tissue-derived and the blood-derived DC also show fundamental differences in maturational status and antigen presenting capabilities. In this review, we summarize the roles played by the different DC types in the steady state and during pathogen infections, relating those roles to maintenance of peripheral tolerance and the induction of immunity. We point out the caveats of assuming that the DC that collect antigens are the ones involved in their presentation, emphasizing the phenomenon of antigen transfer as an important component of the immune response.
Most lymphoid organ dendritic cell types are phenotypically and functionally immature
Publisher: American Society of Hematology
Date: 15-09-2003
DOI: 10.1182/BLOOD-2003-02-0513
Abstract: Dendritic cells (DCs) have been thought to follow a life history, typified by Langerhans cells (LCs), with 2 major developmental stages: an immature stage that captures antigens in the periphery and a mature stage that presents those antigens in the lymphoid organs. However, a systematic assessment of the maturity of lymphoid organ DCs has been lacking. We have analyzed the maturity of the DC types found in the steady state in the spleen, lymph nodes (LNs), and thymus. The DCs that migrate into the iliac, mesenteric, mediastinal, or subcutaneous LNs from peripheral tissues were mature and therefore could not process and present newly encountered antigens. However, all the other DC types were phenotypically and functionally immature: they expressed low levels of surface major histocompatibility complex class II (MHC II) and CD86, accumulated MHC II in their endosomes, and could present newly encountered antigens. These immature DCs could be induced to mature by culture in vitro or by inoculation of inflammatory stimuli in vivo. Therefore, the lymphoid organs contain a large cohort of immature DCs, most likely for the maintenance of peripheral tolerance, which can respond to infections reaching those organs and mature in situ.
Ubiquitin Ligase MARCH8 attenuates Graft versus Host Disease via Regulation of Gut Epithelial Cell Surface MHC II Expression.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2018
Membrane-associated RING-CH (MARCH) proteins down-regulate cell surface expression of the interleukin-6 receptor alpha chain (IL6Rα)
Publisher: Portland Press Ltd.
Date: 11-10-2019
DOI: 10.1042/BCJ20190577
Abstract: Interleukin 6 (IL6) is a cytokine that regulates a number of important immune and inflammatory pathways. We used the ability of IL6 to inhibit the clonal proliferation of the mouse M1 myeloid leukemia cell line in agar to positively screen a cDNA expression library for proteins that inhibited IL6 activity. We found three clones completely resistant to IL6 that contained the cDNA for the Membrane-Associated RING-CH E3 ubiquitin ligase MARCH2. MARCH2 is a member of a family of membrane-bound E3 ubiquitin ligases that target cell surface receptors for degradation. MARCH2 overexpressing M1 clones retained responsiveness to the related cytokines leukemia inhibitory factor and oncostatin M and we showed that its inhibitory effect was a result of selective down-regulation of the IL6 receptor alpha chain and not the shared receptor subunit, gp130 or other signalling molecules. This activity of MARCH2 was also shared with related proteins MARCH4, MARCH9 and an isoform of MARCH3. The transmembrane domains and C-terminal domains, as well as a functional RING domain, of MARCH proteins were all required for substrate recognition and down-regulation. Genetic deletion of in idual MARCH proteins in mice had no or little effect on IL6Rα levels but combined deletions of MARCH2,3 and 4 displayed elevated steady-state levels of IL6Rα in selected haemopoietic cell subsets including CD8+ and CD4+ T cells. These studies extend the potential immunosuppressive roles of MARCH proteins to include down-regulation of IL6 inflammatory responses.
A molecular basis underpinning the T cell receptor heterogeneity of mucosal-associated invariant T cells
Publisher: Rockefeller University Press
Date: 21-07-2014
DOI: 10.1084/JEM.20140484
Abstract: Mucosal-associated invariant T (MAIT) cells express an invariant T cell receptor (TCR) α-chain (TRAV1-2 joined to TRAJ33, TRAJ20, or TRAJ12 in humans), which pairs with an array of TCR β-chains. MAIT TCRs can bind folate- and riboflavin-based metabolites restricted by the major histocompatibility complex (MHC)-related class I−like molecule, MR1. However, the impact of MAIT TCR and MR1-ligand heterogeneity on MAIT cell biology is unclear. We show how a previously uncharacterized MR1 ligand, acetyl-6-formylpterin (Ac-6-FP), markedly stabilized MR1, potently up-regulated MR1 cell surface expression, and inhibited MAIT cell activation. These enhanced properties of Ac-6-FP were attributable to structural alterations in MR1 that subsequently affected MAIT TCR recognition via conformational changes within the complementarity-determining region (CDR) 3β loop. Analysis of seven TRBV6-1+ MAIT TCRs demonstrated how CDR3β hypervariability impacted on MAIT TCR recognition by altering TCR flexibility and contacts with MR1 and the Ag itself. Ternary structures of TRBV6-1, TRBV6-4, and TRBV20+ MAIT TCRs in complex with MR1 bound to a potent riboflavin-based antigen (Ag) showed how variations in TRBV gene usage exclusively impacted on MR1 contacts within a consensus MAIT TCR-MR1 footprint. Moreover, differential TRAJ gene usage was readily accommodated within a conserved MAIT TCR-MR1-Ag docking mode. Collectively, MAIT TCR heterogeneity can fine-tune MR1 recognition in an Ag-dependent manner, thereby modulating MAIT cell recognition.
Characterization of an Immediate Splenic Precursor of CD8+ Dendritic Cells Capable of Inducing Antiviral T Cell Responses
Publisher: The American Association of Immunologists
Date: 04-2009
Abstract: Mouse spleens contain three major dendritic cell (DC) populations: plasmacytoid DC, conventional CD8+CD24+ DC (CD8+ DC), and conventional CD8−CD24− DC (CD8− DC). We have previously shown that CD8+ DC are the major cross-presenting subtype in vivo and are the main inducers of antiviral cytotoxic T lymphocyte responses. Here we show that after depletion of CD8+ DC, the only DC capable of viral Ag presentation was a small subset that expresses CD24 but not CD8. This CD8−CD24+ DC population is greatly expanded in mice treated with the DC growth factor FMS-like tyrosine kinase 3 ligand. The CD8−CD24+ DC represent an immediate precursor of CD8+ DC, as demonstrated by their expression pattern of characteristic markers of CD8+ DC, their capacity to cross-present in vitro, and their conversion into CD8+ DC upon adoptive transfer into recipient mice. Accordingly, the lifespan of transferred CD8−CD24+ DC in vivo was greatly enhanced as compared with terminally differentiated CD8+ DC. Moreover, in a vaccination protocol, CD8−CD24+ DC induced stronger T cell responses and accelerated viral clearance of HSV-1 compared with CD8+ DC. Our results demonstrate that the ability to cross-present first appears in an immediate precursor population of CD8+ DC that does not yet express CD8. The enhanced capacity of CD8−CD24+ DC to induce immune responses upon adoptive transfer makes them an attractive novel tool for DC-based immunotherapies.
Normal proportion and expression of maturation markers in migratory dendritic cells in the absence of germs or Toll‐like receptor signaling
Publisher: Wiley
Date: 20-11-2007
Abstract: Dendritic cells (DCs) play major roles in immunosurveillance. In peripheral tissues, 'immature' DCs are dedicated to capturing antigens. Detection of pathogens through Toll-like receptors (TLRs) triggers DC migration to the lymph nodes (LNs), where they acquire a 'mature' phenotype specialized at presenting antigens. However, DCs migrate from tissues and mature even in the absence of overt infections. This has been attributed to detection of commensal flora in the skin, the gut or other peripheral tissues in the steady state. To test this assumption, we have analyzed the DCs contained in the lymphoid organs of germ-free mice and of mice lacking the TLR adapter molecules, MyD88 and TRIF. We show that the proportion and expression of maturation markers in DC immigrants in the LNs of these mice are similar to those in normal mice. These results suggest that DC migration from tissues, followed by their phenotypic maturation, is regulated in the steady state by an inherent program of DC differentiation or by the release of low levels of inflammatory signals from normal tissues.
Physiological Substrates and Ontogeny-Specific Expression of the Ubiquitin Ligases MARCH1 and MARCH8
Publisher: Cold Spring Harbor Laboratory
Date: 15-04-2021
DOI: 10.1101/2021.04.15.439921
Abstract: MARCH1 and MARCH8 are ubiquitin ligases that control the expression and trafficking of critical immunoreceptors. Understanding of their function is h ered by three major knowledge gaps: (i) it is unclear which cell types utilize these ligases (ii) their level of redundancy is unknown and (iii) most of their putative substrates have been described in cell lines, often overexpressing MARCH1 or MARCH8, and it is unclear which substrates are regulated by either ligase in vivo . Here we address these questions by systematically analyzing the immune cell repertoire of MARCH1- or MARCH8-deficient mice, and applying unbiased proteomic profiling of the plasma membrane of primary cells to identify MARCH1 and MARCH8 substrates. Only CD86 and MHC II were unequivocally identified as immunoreceptors regulated by MARCH1 and MARCH8, but each ligase carried out its function in different tissues. MARCH1 regulated MHC II and CD86 in professional and “atypical” antigen presenting cells of hematopoietic origin, whereas MARCH8 only operated in non-hematopoietic cells. Our results reveal that the range of cells constitutively endowed with antigen-presentation capacity is wider than generally appreciated. They also establish MARCH1 and MARCH8 as specialized regulators of CD4+ T cell immunity in two ontogenically distinct cellular compartments.
Serpinb9 is a marker of antigen cross-presenting dendritic cells
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.MOLIMM.2016.12.011
Abstract: Serpinb9 (Sb9, also called Spi6) is an intracellular inhibitor of granzyme B (grB) that protects cytotoxic lymphocytes from grB-mediated death. In addition, Sb9 is also expressed in accessory immune cells, including dendritic cells (DCs), although its role is debated. Recently, we have demonstrated that Sb9 plays a grB-independent role in cross-presentation of antigens by CD8
Different cross-presentation pathways in steady-state and inflammatory dendritic cells
Publisher: Proceedings of the National Academy of Sciences
Date: 12-2009
Abstract: Presentation of exogenous antigens on MHC class I molecules, termed cross-presentation, is essential for the induction of CD8 T-cell responses and is carried out by specialized dendritic cell (DC) subsets. The mechanisms involved remain unclear. It has been proposed that antigens could be transported by endocytic receptors, such as the mannose receptor (MR) in the case of soluble ovalbumin, into early endosomes in which the cross-presentation machinery would be recruited. In these endosomal compartments, peptides would be trimmed by the aminopeptidase IRAP before loading onto MHC class I molecules. Here, we have investigated the contribution of this pathway to cross-presentation by steady-state CD8 + DC and inflammatory monocyte-derived DC (moDC) generated in vivo. We demonstrate that IRAP and MR are dispensable for cross-presentation by CD8 + DC and for cross-priming. Moreover, we could not find any evidence for ersion of endocytosed antigen into IRAP-containing endosomes in these cells. However, cross-presentation was impaired in moDC deficient in IRAP or MR, confirming the role of these two molecules in inflammatory DC. These results demonstrate that the mechanisms responsible for cross-priming by steady-state and inflammatory DC are different, which has important implications for vaccine design.
Antibody-mediated targeting of antigen to C-type lectin-like receptors Clec9A and Clec12A elicits different vaccination outcomes
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.MOLIMM.2016.12.010
Abstract: Targeting antigen (Ag) to dendritic cell (DC) surface receptors is a potential new mode of vaccination. C-type lectin-like receptors Clec9A and Clec12A are attractive receptor targets however their targeting in vivo elicits significantly different outcomes for unknown reasons. To gain insight into the mechanisms responsible, we have examined the intrinsic capacity of Clec9A and Clec12A to elicit MHC I and MHC II Ag presentation following ex vivo targeting with primary murine DC. Both receptors exhibited high rates of internalization by CD8
Target Density, Not Affinity or Avidity of Antigen Recognition, Determines Adoptive T Cell Therapy Outcomes in a Mouse Lymphoma Model
Publisher: The American Association of Immunologists
Date: 05-2016
Abstract: Adoptive T cell therapy (ACT) with antitumor CTL is a promising and tailored treatment against cancer. We investigated the role played by the affinity and avidity of the interaction between the tumor and the CTL on the outcome of ACT against a mouse non-Hodgkin B cell lymphoma that expresses OVA as a model neoantigen. ACT was assessed under conditions where antitumor CTL expressed TCR of varying affinity for OVA. We also assessed conditions where the avidity of Ag recognition varied because the lymphoma cells expressed high or low levels of OVA. Efficient eradication of small tumor burdens was achieved by high- or low-affinity CTL. Tumors expressing low levels of OVA could also be eliminated. However, ACT against large tumor burdens was unsuccessful, accompanied by CTL deletion and functional impairment. This negative outcome was not prevented by lowering the affinity of the CTL or the expression of OVA in the lymphoma. Thus, tumor burden, rather than CTL affinity or avidity, appears to be the main determinant of ACT outcomes in our lymphoma model. Insofar as our results can be extrapolated to the clinical setting, they imply that the range of CTL and tumor-associated Ag combinations that may be effectively harnessed in ACT against lymphoma may be wider than generally assumed. CTL expressing low-affinity TCR may be effective against lymphoma, and lowly expressed tumor-associated Ag should be considered as potential targets, but tumor reduction should always be implemented before infusion of the CTL.
GM-CSF increases cross-presentation and CD103 expression by mouse CD8+ spleen dendritic cells
Publisher: Wiley
Date: 04-08-2011
Abstract: Resident CD8(+) DCs perform several functions, including cross-presenting antigen and rapidly engulfing the Gram-positive intracellular pathogen Listeria monocytogenes. Little is known about how these functions of CD8(+) DCs are modulated. Here, we show that granulocyte-macrophage CSF (GM-CSF), a cytokine that exists at low levels at steady state but is elevated during infection and inflammation, enhances cross-presentation and rapid uptake of L. monocytogenes by resident CD8(+) DCs. This previously unrecognized functional enhancement of CD8(+) DCs by GM-CSF was independent of promoting DC survival in vitro. Enhancement of these functions by GM-CSF was also marked by CD103 expression on CD8(+) DCs that was strongly regulated by GM-CSF. Our findings not only identify GM-CSF as a key molecule regulating CD8(+) DC function, but also as a factor responsible for functional heterogeneity of CD8(+) DCs that is at least substantially demarcated by CD103 expression.
MR1 antigen presentation to MAIT cells: new ligands, diverse pathways?
Publisher: Elsevier BV
Date: 06-2018
DOI: 10.1016/J.COI.2018.04.022
Abstract: The major histocompatibility complex class I-related molecule MR1 is the only antigen (Ag) presenting molecule that captures and displays vitamin B-derived metabolites that are unique to a wide array of microbes. Presentation of these metabolite Ag at the cell surface activates mucosal-associated invariant T (MAIT) cells, a highly abundant innate-like T cell population, and represents a recently-described mechanism used by the mammalian immune system to sense pathogenic or commensal microbes. Our understanding of the cell biology of how MR1 accomplishes this unique task is still evolving, but recent advances are allowing a general picture to emerge. Further, the list of metabolites presented by MR1 is expanding both by identification of natural metabolites and the design of synthetic ligands. Here we review the latest studies contributing to our growing understanding of this rapidly expanding field.
The Protease Inhibitor Cystatin C Is Differentially Expressed among Dendritic Cell Populations, but Does Not Control Antigen Presentation
Publisher: The American Association of Immunologists
Date: 15-11-2003
DOI: 10.4049/JIMMUNOL.171.10.5003
Abstract: Dendritic cells (DC) undergo complex developmental changes during maturation. The MHC class II (MHC II) molecules of immature DC accumulate in intracellular compartments, but are expressed at high levels on the plasma membrane upon DC maturation. It has been proposed that the cysteine protease inhibitor cystatin C (CyC) plays a pivotal role in the control of this process by regulating the activity of cathepsin S, a protease involved in removal of the MHC II chaperone Ii, and hence in the formation of MHC II-peptide complexes. We show that CyC is differentially expressed by mouse DC populations. CD8+ DC, but not CD4+ or CD4−CD8− DC, synthesize CyC, which accumulates in MHC II+L + compartments. However, Ii processing and MHC II peptide loading proceeded similarly in all three DC populations. We then analyzed MHC II localization and Ag presentation in CD8+ DC, bone marrow-derived DC, and spleen-derived DC lines, from CyC-deficient mice. The absence of CyC did not affect the expression, the subcellular distribution, or the formation of peptide-loaded MHC II complexes in any of these DC types, nor the efficiency of presentation of exogenous Ags. Therefore, CyC is neither necessary nor sufficient to control MHC II expression and Ag presentation in DC. Our results also show that CyC expression can differ markedly between closely related cell types, suggesting the existence of hitherto unrecognized mechanisms of control of CyC expression.
Modulation of antigen presentation by intracellular trafficking
Publisher: Elsevier BV
Date: 06-2015
DOI: 10.1016/J.COI.2014.12.006
Abstract: Processing and loading of antigen into major histocompatibility complex molecules (MHC) occurs in specific intracellular compartments. Accessing MHC loading compartments requires trafficking via specific pathways, some of which have yet to be fully characterized. For MHC I, cross-presentation involves antigen trafficking to a specialised compartment. We review the features of this compartment and how it is accessed by different mechanisms of antigen capture and internalization. We also summarize advances in understanding how antigen efficiently accesses the MHC II loading compartment, with particular focus on the role of autophagy. Understanding the mechanisms that control how antigen is trafficked to specific compartments for loading and presentation is crucial if these pathways are to be manipulated more effectively in settings of vaccination.
Factors determining the spontaneous activation of splenic dendritic cells in culture
Publisher: SAGE Publications
Date: 25-05-2010
Abstract: Dendritic cells (DCs) serve as a link between the innate and adaptive immune systems. The activation state of DCs is crucial in this role. However, when DCs are isolated from lymphoid tissues, purified and placed in culture they undergo ‘spontaneous’ activation. The basis of this was explored, using up-regulation of DC surface MHC II, CD40, CD80 and CD86 as indicators of DC activation. No evidence was found for DC damage during isolation or for microbial products causing the activation. The culture activation of spleen DCs differed from that of Langerhans cells when released from E-cadherin-mediated adhesions, since E-cadherin was not detected and activation still occurred with β-catenin null DCs. Much of the activation could be attributed to DC—DC interactions. Although increases in surface MHC II levels occurred under all culture conditions tested, the increase in expression of CD40, CD80 and CD86 was much less under culture conditions where such interactions were minimised. DC-to-DC contact under the artificial conditions of high DC concentration in culture induced the production of soluble factors and these, in turn, induced the up-regulation of co-stimulatory molecules on the DC surface.
Respiratory DC Use IFITM3 to Avoid Direct Viral Infection and Safeguard Virus-Specific CD8+ T Cell Priming
Publisher: Public Library of Science (PLoS)
Date: 23-11-2015
Selecting cells with different Alzheimer's disease γ‐secretase activity using FACS
Publisher: Wiley
Date: 13-01-2003
DOI: 10.1046/J.1432-1033.2003.03405.X
Abstract: The ultimate step in Alzheimer's disease Abeta generation involves gamma-secretase, which releases Abeta from its membrane-bound precursor. A similar presenilin-dependent proteolytic activity is implicated in the release of the Notch intracellular domain. We have developed a novel assay for gamma-secretase activity based on green fluorescent protein detection. This involves cotransfection of a substrate-activator based on the amyloid precursor protein or the Notch sequence and a fluorescent reporter gene. Stable fluorescent cell populations were selected by fluorescent activated cell sorting and characterized. This assay enabled the identification and sorting of populations, which differ in their levels of gamma-secretase activity, with high fluorescent cells producing more Abeta than low fluorescent cells. Specific gamma-secretase inhibitors, L-685,458 and MW167, reduced cell fluorescence in a dose-dependent manner that paralleled inhibition of Abeta secretion. Overexpression of presenilin 1 increased the cell fluorescence. Cells expressing presenilin with different aspartate mutations (D257A, D385A and D257A/D385A) or exon 9 deletion mutation showed reduced fluorescence. The single aspartate mutations showed a concomitant reduction in Abeta secretion, whereas the D257A/D385A and DeltaE9 mutations had no effect on Abeta secretion.
Dendritic cell Flt3 – regulation, roles and repercussions for immunotherapy
Publisher: Wiley
Date: 02-07-2021
DOI: 10.1111/IMCB.12484
Abstract: Dendritic cells (DCs) are essential for initiating immune responses. Depending on the environment, the type of DC and the way in which they interact with T cells, these immune responses can be beneficial or detrimental. DCs can be exploited as cellular vectors for vaccines against infection and cancer. The development and maintenance of DCs is dependent on the FMS‐like tyrosine kinase 3 (Flt3)/Flt3 ligand (Flt3L) signaling cascade. Flt3 is also one of the most commonly mutated genes in acute myeloid leukemia and as such represents an attractive drug target. In this review, Flt3 is discussed with a particular focus on DCs. We detail the lifecycle of Flt3, from transcription to degradation, and interrogate recent studies as to how this pathway can be manipulated for immunotherapy, vaccination and treatment of autoimmune disease.
MR1 presentation of vitamin B-based metabolite ligands
Publisher: Elsevier BV
Date: 06-2015
DOI: 10.1016/J.COI.2014.12.004
Abstract: The major histocompatibility complex class I-related molecule MR1 can bind a novel class of antigens, namely a family of related small organic vitamin B metabolites. When bound to MR1 these metabolites are presented to a population of innate-like T cells, mucosal-associated invariant T (MAIT) cells that express a semi-invariant T cell receptor (TCR). Several non-activating and activating MR1-restricted ligands have been described, which are the degradation products of, or intermediates of, vitamin B9 (folic acid) or vitamin B2 (riboflavin), respectively. The MAIT-activating intermediates of the riboflavin synthesis pathway are unique to a wide range of microbes, and accordingly represent a molecular signature of microbial infection. Recently insights into the binding of these vitamin B metabolites to MR1, and subsequent recognition by the MAIT TCR, have been gleaned, illustrating a novel antigen presentation system.
Author Correction: Alveolar macrophages are epigenetically altered after inflammation, leading to long-term lung immunoparalysis
Publisher: Springer Science and Business Media LLC
Date: 24-06-2020
Targeting antigen to bone marrow stromal cell‐2 expressed by conventional and plasmacytoid dendritic cells elicits efficient antigen presentation
Publisher: Wiley
Date: 06-02-2013
Abstract: Bone marrow stromal cell-2 (BST-2) has major roles in viral tethering and modulation of interferon production. Here we investigate BST-2 as a receptor for the delivery of antigen to dendritic cells (DCs). We show that BST-2 is expressed by a panel of mouse and human DC subsets, particularly under inflammatory conditions. The outcome of delivering antigen to BST-2 expressed by steady state and activated plasmacytoid DC (pDC) or conventional CD8(+) and CD8(-) DCs was determined. T-cell responses were measured for both MHC class I (MHCI) and MHC class II (MHCII) antigen presentation pathways in vitro. Delivering antigen via BST-2 was compared with that via receptors DEC205 or Siglec-H. We show that despite a higher antigen load and faster receptor internalisation, when antigen is delivered to steady state or activated pDC via BST-2, BST-2-targeted activated conventional DCs present antigen more efficiently. Relative to DEC205, BST-2 was inferior in its capacity to deliver antigen to the MHCI cross-presentation pathway. In contrast, BST-2 was superior to Siglec-H at initiating either MHCI or MHCII antigen presentation. In summary, BST-2 is a useful receptor to target with antigen, given its broad expression pattern and ability to access both MHCI and MHCII presentation pathways with relative efficiency.
Ubiquitination of MHC Class II Is Required for Development of Regulatory but Not Conventional CD4+ T Cells
Publisher: The American Association of Immunologists
Date: 09-2020
Abstract: MHC class II (MHC II) displays peptides at the cell surface, a process critical for CD4+ T cell development and priming. Ubiquitination is a mechanism that dictates surface MHC II with the attachment of a polyubiquitin chain to peptide-loaded MHC II, promoting its traffic away from the plasma membrane. In this study, we have examined how MHC II ubiquitination impacts the composition and function of both conventional CD4+ T cell and regulatory T cell (Treg) compartments. Responses were examined in two models of altered MHC II ubiquitination: MHCIIKRKI/KI mice that express a mutant MHC II unable to be ubiquitinated or mice that lack membrane-associated RING-CH 8 (MARCH8), the E3 ubiquitin ligase responsible for MHC II ubiquitination specifically in thymic epithelial cells. Conventional CD4+ T cell populations in thymus, blood, and spleen of MHCIIKRKI/KI and March8−/− mice were largely unaltered. In MLRs, March8−/−, but not MHCIIKRKI/KI, CD4+ T cells had reduced reactivity to both self– and allogeneic MHC II. Thymic Treg were significantly reduced in MHCIIKRKI/KI mice, but not March8−/− mice, whereas splenic Treg were unaffected. Neither scenario provoked autoimmunity, with no evidence of immunohistopathology and normal levels of autoantibody. In summary, MHC II ubiquitination in specific APC types does not have a major impact on the conventional CD4+ T cell compartment but is important for Treg development.
Endogenous Murine BST-2/Tetherin Is Not a Major Restriction Factor of Influenza A Virus Infection
Publisher: Public Library of Science (PLoS)
Date: 13-11-2015
Butyrophilin 2A1 is essential for phosphoantigen reactivity by gd T cells
Publisher: American Association for the Advancement of Science (AAAS)
Date: 07-02-2020
Abstract: In contrast to the well-studied αβ T cells, which recognize peptide antigens presented by major histocompatibility complex (MHC) and MHC-like molecules, how γδ T cells recognize antigens remains largely a mystery. One major class of γδ T cells, designated Vγ9Vδ2 + , is activated by small, phosphorylated nonpeptide antigens, or phosphoantigens, produced by microbes and cancer cells. Rigau et al. found that these cells needed the combination of two immunoglobulin superfamily members, butyrophilin 2A1 (BTN2A1) and BTN3A1, on their cell surface to recognize these phosphoantigens. BTN2A1 directly binds the Vγ9 + domain of the T cell receptor (TCR), whereas a second ligand, potentially BTN3A1, binds the Vδ2 and γ-chain regions on the opposite side of the TCR. A better understanding of this unexpected form of T cell antigen recognition should inform and enhance future γδ T cell–mediated immunotherapies. Science , this issue p. eaay5516
Cutting Edge: Generation of Splenic CD8+ and CD8− Dendritic Cell Equivalents in Fms-Like Tyrosine Kinase 3 Ligand Bone Marrow Cultures
Publisher: The American Association of Immunologists
Date: 06-2005
DOI: 10.4049/JIMMUNOL.174.11.6592
Abstract: We demonstrate that functional and phenotypic equivalents of mouse splenic CD8+ and CD8− conventional dendritic cell (cDC) subsets can be generated in vitro when bone marrow is cultured with fms-like tyrosine kinase 3 (flt3) ligand. In addition to CD45RAhigh plasmacytoid DC, two distinct CD24high and CD11bhigh cDC subsets were present, and these subsets showed equivalent properties to splenic CD8+ and CD8− cDC, respectively, in the following: 1) surface expression of CD11b, CD24, and signal regulatory protein-α 2) developmental dependence on, and mRNA expression of, IFN regulatory factor-8 3) mRNA expression of TLRs and chemokine receptors 4) production of IL-12 p40/70, IFN-α, MIP-1α, and RANTES in response to TLR ligands 5) expression of cystatin C and 6) cross-presentation of exogenous Ag to CD8 T cells. Furthermore, despite lacking surface CD8 expression, the CD24high subset contained CD8 mRNA and up-regulated surface expression when transferred into mice. This culture system allows access to bona fide counterparts of the splenic DC subsets.
How MR1 Presents a Pathogen Metabolic Signature to Mucosal-Associated Invariant T (MAIT) Cells
Publisher: Elsevier BV
Date: 09-2017
Abstract: Mucosal-associated invariant T (MAIT) cells are innate-like lymphocytes restricted by the antigen (Ag)-presenting molecule MHC class I (MHC I)-related protein 1 (MR1). The Ags presented by MR1 are vitamin B-related Ags (VitBAgs), 'building-block' metabolites of riboflavin that are synthesized by a range of microbes. MR1 presentation is thus a unique mechanism for the immune detection of a pathogen metabolic signature. While the full picture of how MR1 accomplishes this remains incomplete, recent data show that, unlike other MHC molecules, MR1 operates by a presentation-on-demand mechanism. In the absence of metabolite ligands MR1 is mostly stored in the endoplasmic reticulum (ER). Ligand binding leads to the formation of a Schiff-base bond between MR1 and its ligand, triggering a 'molecular switch' in MR1 that allows trafficking of the complexes to the cell surface. The complexes are subsequently internalized and mostly degraded irrespective of the affinity of the interaction between MR1 and its ligands. Here we review past and recent studies that have contributed to defining this pathway and propose new directions for a full understanding of the role and mechanisms of MR1 Ag presentation.
Antibody-targeted vaccination to lung dendritic cells generates tissue-resident memory CD8 T cells that are highly protective against influenza virus infection
Publisher: Elsevier BV
Date: 09-2015
DOI: 10.1038/MI.2014.133
Abstract: Influenza virus gains entry into the body by inhalation and initiates its replication cycle within the lung. The early stage of infection, while the virus is confined to the lung mucosa, provides the ideal window of opportunity for an effective immune response to control the infection. Tissue-resident memory (Trm) CD8 T cells, located in a variety of tissues including the lung, are ideally situated to act during this window and stall the infection. The factors involved in the differentiation of lung Trm cells remain poorly defined. We demonstrate that recognition of antigen presented locally by dendritic cells (DCs) and transforming growth factor-β (TGFβ) signaling are both required. We exploited this knowledge to develop an antibody-targeted vaccination approach to generate lung Trm cells. Delivering antigen exclusively to respiratory DCs results in the development of lung CD8 Trm cells that are highly protective against lethal influenza challenge. Our results describe an effective vaccination strategy that protects against influenza virus infection.
Type 1 conventional dendritic cell fate and function are controlled by DC-SCRIPT
Publisher: American Association for the Advancement of Science (AAAS)
Date: 02-04-2021
DOI: 10.1126/SCIIMMUNOL.ABF4432
Abstract: DC-SCRIPT is a key transcription factor controlling type 1 conventional dendritic cell fate and function.
Targeting the Gut Vascular Endothelium Induces Gut Effector CD8 T Cell Responses Via Cross-Presentation by Dendritic Cells
Publisher: The American Association of Immunologists
Date: 11-2007
DOI: 10.4049/JIMMUNOL.179.9.5678
Abstract: Systemic delivery of Ag usually induces poor mucosal immunity. To improve the CD8 T cell response at mucosal sites, we targeted the Ag to MAdCAM-1, a mucosal addressin cell adhesion molecule expressed mainly by high endothelial venules (HEV) in mesenteric lymph nodes (MLN) and Peyer’s patches of gut-associated lymphoid tissue. When chemical conjugates of anti-MAdCAM-1 Ab and model Ag OVA were injected i.v., a greatly enhanced proliferative response of Ag-specific OT-I CD8 T cells was detected in MLN. This was preceded by prolonged accumulation, up to 2 wk, of the anti-MAdCAM OVA conjugate on HEV of Peyer’s patches and MLN. In contrast, nontargeted OVA conjugate was very inefficient in inducing OT-I CD8 T cell proliferation in MLN and required at least 20-fold more Ag to induce a comparable response. In addition, MAdCAM targeting elicits an endogenous OVA-specific CD8 T cell response, evident by IFN-γ production and target killing. Induced response offers protection against an OVA-expressing B cell lymphoma. We propose that the augmentation of gut CD8 T cell responses by MAdCAM targeting is due to both accumulation of Ag in the HEV and conversion of a soluble Ag to a cell-associated one, allowing cross-presentation by DCs.
MARCH ligases in immunity
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.COI.2019.03.001
Abstract: Membrane associated RING-CH (MARCH) ubiquitin ligases control the stability, trafficking and function of important immunoreceptors, including MHC molecules and costimulatory molecule CD86. Regulation of the critical antigen presenting molecule MHC II by MARCH1 and the control of MARCH1 expression by inflammatory stimuli is a key step in the function of antigen presenting cells. MHC II ubiquitination by MARCH8 and CD83 plays a critical role in T cell thymic selection. Recent studies reveal new immune functions of MARCH ligases in innate immunity, regulation of FcγR expression and T
Cognate CD4+ Help Elicited by Resting Dendritic Cells Does Not Impair the Induction of Peripheral Tolerance in CD8+ T Cells
Publisher: The American Association of Immunologists
Date: 15-02-2007
DOI: 10.4049/JIMMUNOL.178.4.2094
Abstract: Peripheral tolerance is required to prevent autoimmune tissue destruction by self-reactive T cells that escape negative selection in the thymus. One mechanism of peripheral tolerance in CD8+ T cells is their activation by resting dendritic cells (DC). In contrast, DC can be “licensed” by CD4+ T cells to induce cytotoxic function in CD8+ T cells. The question that then arises, whether CD4+ T cell help could impair peripheral tolerance induction in self-reactive CD8+ T cells, has not been addressed. In this study we show that CD4+ T cell activation by resting DC results in helper function that transiently promotes the expansion and differentiation of cognate CD8+ T cells. However, both the CD4+ and CD8+ T cell populations ultimately undergo partial deletion and acquire Ag unresponsiveness, disabling their ability to destroy OVA-expressing pancreatic β cells and cause diabetes. Thus, effective peripheral tolerance can be induced by resting DC in the presence of CD4+ and CD8+ T cells with specificity for the same Ag.
Blood‐stage Plasmodium berghei infection leads to short‐lived parasite‐associated antigen presentation by dendritic cells
Publisher: Wiley
Date: 06-2010
Abstract: Despite extensive evidence that Plasmodium species are capable of stimulating the immune system, the association of malaria with a higher incidence of other infectious diseases and reduced responses to vaccination against unrelated pathogens suggests the existence of immune suppression. Recently, we provided evidence that blood-stage Plasmodium berghei infection leads to suppression of MHC class I-restricted immunity to third party (non-malarial) antigens as a consequence of systemic DC activation. This earlier study did not, however, determine whether reactivity was also impaired to MHC class II-restricted third party antigens or to Plasmodium antigens themselves. Here, we show that while P. berghei-expressed antigens were presented early in infection, there was a rapid decline in presentation within 4 days, paralleling impairment in MHC class I- and II-restricted presentation of third party antigens. This provides important evidence that P. berghei not only causes immunosuppression to subsequently encountered third party antigens, but also rapidly limits the capacity to generate effective parasite-specific immunity.
Switching from a restricted to an effective CD4 T cell response by activating CD8+ murine dendritic cells with a Toll-like receptor 9 ligand
Publisher: Wiley
Date: 11-2005
Abstract: Freshly isolated quiescent splenic dendritic cell (DC) subtypes differ in their capacity to activate naive CD4 T cells in culture. The CD8+ DC showed a reduced capacity to stimulate T cell proliferation compared to either of the CD8- DC subsets, regardless of antigen and DC dose. In contrast to CD8- DC, the quiescent CD8+ DC did not induce IFN-gamma production from CD4 T cells. The difference between the DC subtypes appeared to be at the level of initial surface molecule interactions, but could not be attributed to differences in expression of MHC class II or B7 family molecules, or to the expression of Fas ligand on DC. However, when activated by inclusion of the Toll-like receptor 9 ligand CpG in culture, CD8+ DC became potent stimulators of both CD4 T cell proliferation and IFN-gamma production. In contrast, similar activation of CD8- DC produced a more modest increase in capacity to stimulate CD4 T cell proliferation and no increase in capacity to stimulate IFN-gamma production. The difference between a quiescent and an activated state is therefore more extreme for CD8+ than for CD8- DC. The especially tight regulation of the activity of CD8+ DC may be essential for the maintenance of self tolerance.
DNA-based probes for flow cytometry analysis of endocytosis and recycling
Publisher: Wiley
Date: 07-02-2017
DOI: 10.1111/TRA.12466
Abstract: The internalization of proteins plays a key role in cell development, cell signaling and immunity. We have previously developed a specific hybridization internalization probe (SHIP) to quantitate the internalization of proteins and particles into cells. Herein, we extend the utility of SHIP to examine both the endocytosis and recycling of surface receptors using flow cytometry. SHIP was used to monitor endocytosis of membrane-bound transferrin receptor (TFR) and its soluble ligand transferrin (TF). SHIP enabled measurements of the proportion of surface molecules internalized, the internalization kinetics and the proportion and rate of internalized molecules that recycle to the cell surface with time. Using this method, we have demonstrated the internalization and recycling of holo-TF and an antibody against the TFR behave differently. This assay therefore highlights the implications of receptor internalization and recycling, where the internalization of the receptor-antibody complex behaves differently to the receptor-ligand complex. In addition, we observe distinct internalization patterns for these molecules expressed by different subpopulations of primary cells. SHIP provides a convenient and high throughput technique for analysis of trafficking parameters for both cell surface receptors and their ligands.
A multi-scale model for hair follicles reveals heterogeneous domains driving rapid spatiotemporal hair growth patterning
Publisher: eLife Sciences Publications, Ltd
Date: 11-07-2017
DOI: 10.7554/ELIFE.22772
Abstract: The control principles behind robust cyclic regeneration of hair follicles (HFs) remain unclear. Using multi-scale modeling, we show that coupling inhibitors and activators with physical growth of HFs is sufficient to drive periodicity and excitability of hair regeneration. Model simulations and experimental data reveal that mouse skin behaves as a heterogeneous regenerative field, composed of anatomical domains where HFs have distinct cycling dynamics. Interactions between fast-cycling chin and ventral HFs and slow-cycling dorsal HFs produce bilaterally symmetric patterns. Ear skin behaves as a hyper-refractory domain with HFs in extended rest phase. Such hyper-refractivity relates to high levels of BMP ligands and WNT antagonists, in part expressed by ear-specific cartilage and muscle. Hair growth stops at the boundaries with hyper-refractory ears and anatomically discontinuous eyelids, generating wave-breaking effects. We posit that similar mechanisms for coupled regeneration with dominant activator, hyper-refractory, and wave-breaker regions can operate in other actively renewing organs.
Differential antigen requirements by diverse MR1‐restricted T cells
Publisher: Wiley
Date: 15-02-2022
DOI: 10.1111/IMCB.12535
Marginal zone B cells acquire dendritic cell functions by trogocytosis
Publisher: American Association for the Advancement of Science (AAAS)
Date: 11-02-2022
Abstract: Marginal zone (MZ) B cells produce broad-spectrum antibodies that protect against infection early in life. In some instances, antibody production requires MZ B cells to display pathogen antigens bound to major histocompatibility complex class II (MHC II) molecules to T cells. We describe the trogocytic acquisition of these molecules from conventional dendritic cells (cDCs). Complement component 3 (C3) binds to murine and human MHC II on cDCs. MZ B cells recognize C3 with complement receptor 2 (CR2) and trogocytose the MHC II–C3 complexes, which become exposed on their cell surface. The ubiquitin ligase MARCH1 limits the number of MHC II–C3 complexes displayed on cDCs to prevent their elimination through excessive trogocytosis. Capture of C3 by MHC II thus enables the transfer of cDC-like properties to MZ B cells.
Virus-Mediated Suppression of the Antigen Presentation Molecule MR1
Publisher: Elsevier BV
Date: 03-2020
Differential MHC class II synthesis and ubiquitination confers distinct antigen-presenting properties on conventional and plasmacytoid dendritic cells
Publisher: Springer Science and Business Media LLC
Date: 12-10-2008
DOI: 10.1038/NI.1665
Abstract: The importance of conventional dendritic cells (cDCs) in the processing and presentation of antigen is well established, but the contribution of plasmacytoid dendritic cells (pDCs) to these processes, and hence to T cell immunity, remains unclear. Here we showed that unlike cDCs, pDCs continued to synthesize major histocompatibility complex (MHC) class II molecules and the MHC class II ubiquitin ligase MARCH1 long after activation. Sustained MHC class II-peptide complex formation, ubiquitination and turnover rendered pDCs inefficient in the presentation of exogenous antigens but enabled pDCs to continuously present endogenous viral antigens in their activated state. As the antigen-presenting abilities of cDCs and pDCs are fundamentally distinct, these two cell types may activate largely nonoverlapping repertoires of CD4(+) T cells.
Reply to Burgdorf et al.: The mannose receptor is not involved in antigen cross-presentation by steady-state dendritic cells
Publisher: Proceedings of the National Academy of Sciences
Date: 22-03-2010
Cross‐presentation, dendritic cell subsets, and the generation of immunity to cellular antigens
Publisher: Wiley
Date: 05-05-2004
Suppression of MR1 by human cytomegalovirus inhibits MAIT cell activation
Publisher: Frontiers Media SA
Date: 10-02-2023
DOI: 10.3389/FIMMU.2023.1107497
Abstract: The antigen presentation molecule MHC class I related protein-1 (MR1) is best characterized by its ability to present bacterially derived metabolites of vitamin B2 biosynthesis to mucosal-associated invariant T-cells (MAIT cells). Through in vitro human cytomegalovirus (HCMV) infection in the presence of MR1 ligand we investigate the modulation of MR1 expression. Using coimmunoprecipitation, mass spectrometry, expression by recombinant adenovirus and HCMV deletion mutants we investigate HCMV gpUS9 and its family members as potential regulators of MR1 expression. The functional consequences of MR1 modulation by HCMV infection are explored in coculture activation assays with either Jurkat cells engineered to express the MAIT cell TCR or primary MAIT cells. MR1 dependence in these activation assays is established by addition of MR1 neutralizing antibody and CRISPR/Cas-9 mediated MR1 knockout. Here we demonstrate that HCMV infection efficiently suppresses MR1 surface expression and reduces total MR1 protein levels. Expression of the viral glycoprotein gpUS9 in isolation could reduce both cell surface and total MR1 levels, with analysis of a specific US9 HCMV deletion mutant suggesting that the virus can target MR1 using multiple mechanisms. Functional assays with primary MAIT cells demonstrated the ability of HCMV infection to inhibit bacterially driven, MR1-dependent activation using both neutralizing antibodies and engineered MR1 knockout cells. This study identifies a strategy encoded by HCMV to disrupt the MR1:MAIT cell axis. This immune axis is less well characterized in the context of viral infection. HCMV encodes hundreds of proteins, some of which regulate the expression of antigen presentation molecules. However the ability of this virus to regulate the MR1:MAIT TCR axis has not been studied in detail.
A specialized tyrosine-based endocytosis signal in MR1 controls antigen presentation to MAIT cells
Publisher: Rockefeller University Press
Date: 21-09-2022
Abstract: MR1 is a highly conserved microbial immune-detection system in mammals. It captures vitamin B–related metabolite antigens from erse microbes and presents them at the cell surface to stimulate MR1-restricted lymphocytes including mucosal-associated invariant T (MAIT) cells. MR1 presentation and MAIT cell recognition mediate homeostasis through host defense and tissue repair. The cellular mechanisms regulating MR1 cell surface expression are critical to its function and MAIT cell recognition, yet they are poorly defined. Here, we report that human MR1 is equipped with a tyrosine-based motif in its cytoplasmic domain that mediates low affinity binding with the endocytic adaptor protein 2 (AP2) complex. This interaction controls the kinetics of MR1 internalization from the cell surface and minimizes recycling. We propose MR1 uses AP2 endocytosis to define the duration of antigen presentation to MAIT cells and the detection of a microbial metabolic signature by the immune system.
Antibody responses initiated by Clec9A-bearing dendritic cells in normal and Batf3−/− mice
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.MOLIMM.2011.11.008
Abstract: Injection of antigens coupled to antibodies against the dendritic cell (DC) surface molecule Clec9A has been shown to produce strongly enhanced antibody responses even without co-administration of adjuvants, via antigen presentation by DC on MHC class II and consequent production of follicular helper T cells. A series of mutant mice were tested to determine the DC subtypes responsible for this MHC II presentation of targeted antigen, compared to presentation of antigen on MHC I. A new clec9A null mouse was developed these mice did not give enhanced antibody production, confirming the response was dependent on Clec9A-expressing DC. However targeting of antigen to Clec9A in batf3 null mice produced enhanced antibody responses despite the marked reduction in CD8(+) DC, the major Clec9A-expressing DC subtype. This was shown to be dependent on efficient MHC II presentation by minor Clec9A-expressing DC subtypes in the environment of the Batf3(-/-) mice, namely early cells of the CD8 DC lineage and the plasmacytoid-related CD8(+) DC subset, but not by plasmacytoid cells themselves. However in normal mice most MHC II presentation of the Clec9A-targeted antigen was by the major CD8(+) DC population, the DC also responsible for presentation on MHC I.
IL-10 Controls Cystatin C Synthesis and Blood Concentration in Response to Inflammation through Regulation of IFN Regulatory Factor 8 Expression
Publisher: The American Association of Immunologists
Date: 15-03-2011
Abstract: Cystatin C (CstC) is a cysteine protease inhibitor of major clinical importance. Low concentration of serum CstC is linked to atherosclerosis. CstC can prevent formation of amyloid β associated with Alzheimer’s disease and can itself form toxic aggregates. CstC regulates NO secretion by macrophages and is a TGF-β antagonist. Finally, the serum concentration of CstC is an indicator of kidney function. Yet, little is known about the regulation of CstC expression in vivo. In this study, we demonstrate that the transcription factor IFN regulatory factor 8 (IRF-8) is critical for CstC expression in primary dendritic cells. Only those cells with IRF-8 bound to the CstC gene promoter expressed high levels of the inhibitor. Secretion of IL-10 in response to inflammatory stimuli downregulated IRF-8 expression and consequently CstC synthesis in vivo. Furthermore, the serum concentration of CstC decreased in an IL-10–dependent manner in mice treated with the TLR9 agonist CpG. CstC synthesis is therefore more tightly regulated than hitherto recognized. The mechanisms involved in this regulation might be targeted to alter CstC production, with potential therapeutic value. Our results also indicate that caution should be exerted when using the concentration of serum CstC as an indicator of kidney function in conditions in which inflammation may alter CstC production.
Monocyte Signature Associated with Herpes Simplex Virus Reactivation and Neurological Recovery after Brain Injury
Publisher: American Thoracic Society
Date: 08-2022
Cytotoxic T Lymphocytes from Cathepsin B-deficient Mice Survive Normally in Vitro and in Vivo after Encountering and Killing Target Cells
Publisher: Elsevier BV
Date: 10-2006
MR1 antigen presentation to MAIT cells and other MR1-restricted T cells
Publisher: Springer Science and Business Media LLC
Date: 29-09-2023
Induction of antigen‐specific effector‐phase tolerance following vaccination against a previously ignored B‐cell lymphoma
Publisher: Wiley
Date: 16-11-2010
DOI: 10.1038/ICB.2010.131
Abstract: The mechanisms of immune evasion during haematological malignancies are poorly understood. As lymphomas grow in lymphoid organs, it would be expected that if these lymphomas express neo-antigens they should be readily detected by the immune system. To test this assumption, we generated a new non-Hodgkin B-cell lymphoma model expressing the model tumour neo-antigen Ovalbumin (OVA), and analysed the endogenous antigen-specific CD8(+) T-cell response that it elicited in recipient mice. The OVA+ lymphoma cells were eliminated by cytotoxic T lymphocytes (CTL) in mice that had been previously vaccinated against OVA. In contrast, the immune system of naïve mice ignored the malignant cells even though these continuously expressed and presented OVA on their MHC class I molecules. This state of ignorance could be overcome by therapeutic vaccination, which led to the expansion of endogenous anti-OVA-specific CD8(+) T cells. However, the cytotoxic and interferon-γ secretion capacity of these T cells were impaired. The tumour model that we describe thus reproduces several key aspects of human lymphoma tumor ignorance can be broken by vaccination but the ensuing immune response remains ineffective. This model can be exploited to further understand the mechanisms of lymphoma immunoevasion and devise effective immunotherapy.
Systemic activation of dendritic cells by Toll-like receptor ligands or malaria infection impairs cross-presentation and antiviral immunity
Publisher: Springer Science and Business Media LLC
Date: 15-01-2006
DOI: 10.1038/NI1300
Abstract: The mechanisms responsible for the immunosuppression associated with sepsis or some chronic blood infections remain poorly understood. Here we show that infection with a malaria parasite (Plasmodium berghei) or simple systemic exposure to bacterial or viral Toll-like receptor ligands inhibited cross-priming. Reduced cross-priming was a consequence of downregulation of cross-presentation by activated dendritic cells due to systemic activation that did not otherwise globally inhibit T cell proliferation. Although activated dendritic cells retained their capacity to present viral antigens via the endogenous major histocompatibility complex class I processing pathway, antiviral responses were greatly impaired in mice exposed to Toll-like receptor ligands. This is consistent with a key function for cross-presentation in antiviral immunity and helps explain the immunosuppressive effects of systemic infection. Moreover, inhibition of cross-presentation was overcome by injection of dendritic cells bearing antigen, which provides a new strategy for generating immunity during immunosuppressive blood infections.
Tumor antigen processing and presentation depend critically on dendritic cell type and the mode of antigen delivery
Publisher: American Society of Hematology
Date: 15-03-2005
DOI: 10.1182/BLOOD-2004-08-3105
Abstract: Dendritic cells (DCs) are being evaluated for cancer immunotherapy due to their unique ability to induce tumor-directed T-cell responses. Here we report that the type of human DC, the mode of activation, and the strategy for delivery of antigen are 3 critical factors for efficient stimulation of tumor-specific CD8+ and CD4+ T cells. Only CD1c+ blood DCs and monocyte-derived DCs (MoDCs) were capable of presenting epitopes of the full-length tumor antigen NY-ESO-1 on both major histocompatibility complex (MHC) class I (cross-presentation) and MHC II, whereas plasmacytoid DCs were limited to MHC II presentation. Cross-presentation was inefficient for soluble protein, but highly efficient for antigen-antibody immune complexes (NY-ESO-1/IC) and for protein formulated with ISCOMATRIX adjuvant (NY-ESO-1/IMX). DC activation with CD40L further enhanced cross-presentation efficiency. The mode of antigen delivery was found to be a determining factor for cytosolic proteolysis by DCs. Immune complexes (ICs) targeted a slow, proteasome-dependent cross-presentation pathway, whereas ISCOMATRIX (IMX) targeted a fast, proteasome-independent pathway. Both cross-presentation pathways resulted in a long-lived, T-cell stimulatory capacity, which was maintained for several days longer than for DCs pulsed with peptide. This may provide DCs with le opportunities for sensitizing tumor-specific T cells against a broad array of tumor antigen epitopes in lymph nodes.
Endolysosomal proteases and their inhibitors in immunity
Publisher: Springer Science and Business Media LLC
Date: 12-2009
DOI: 10.1038/NRI2671
Abstract: The cellular endolysosomal compartment is dynamic, complex and incompletely understood. Its organelles and constituents vary between different cell types, but endolysosomal proteases are key components of this compartment in all cells. In immune cells, these proteases function in pathogen recognition and elimination, signal processing and cell homeostasis, and they are regulated by dedicated inhibitors. Pathogens can produce analogous proteases to subvert the host immune response. The balance in activity between a protease and its inhibitor can tune the immune response or cause damage as a result of mislocalized proteolysis. In this Review, we highlight recent developments in this area and emphasize the importance of studying the role of endolysosomal proteases, and their natural inhibitors, in the initiation and regulation of immune responses.
Rapid Deletion and Inactivation of CTLs upon Recognition of a Number of Target Cells over a Critical Threshold
Publisher: The American Association of Immunologists
Date: 10-2013
Abstract: Initiation of CTL responses against foreign pathogens also primes anti-self CTLs. Mechanisms of CTL inactivation inhibit anti-self CTLs to prevent tissue damage. These mechanisms are exploited by pathogens and tumors to evade the immune response, and present a major hurdle to adoptive CTL therapies. It is unclear whether CTL inactivation is Ag specific and, if so, which APCs are involved. Potential candidates include the target cells themselves, dendritic cells, myeloid-derived suppressor cells, and macrophages. In this study, we show that lymphoma-specific CTLs are rapidly deleted in an Ag-specific manner after adoptive transfer into lymphoma-bearing mice, and the surviving CTLs are functionally impaired. The only APCs responsible were the target cells directly presenting Ag, notwithstanding the presence of myeloid-derived suppressor cells, and CD8+ dendritic cells cross-presenting tumor Ag. The capacity to inactivate CTLs critically depended on the number of tumor/target cells small numbers of targets were readily killed, but a large number caused quick deletion and functional inactivation of the CTLs. Application of mild, noninflammatory, and nonlymphoablative chemotherapy to specifically reduce tumor burden before CTL injection prevented CTL deletion and inactivation and allowed eradication of tumor. Our results advocate the use of adoptive CTL therapy soon after mild chemotherapy. They also suggest a simple mechanism for Ag-specific impairment of anti-self CTLs in the face of an active anti-foreign CTL response.
Endoplasmic reticulum chaperones stabilize ligand-receptive MR1 molecules for efficient presentation of metabolite antigens
Publisher: Proceedings of the National Academy of Sciences
Date: 21-09-2020
Abstract: A newly discovered system for immunological detection of erse bacterial and fungal pathogens involves the MHC-like host protein called MR1. This molecule scavenges metabolites from the biosynthesis of riboflavin by microbes. MR1 presents these compounds on the surface of antigen-presenting cells, where they interact with T cells known as mucosal-associated invariant T cells and stimulate immunity. Critical aspects of the cell biology of metabolite presentation by MR1 are unknown. Here we generated a fluorescent antigen analog and use it to show that MR1 captures its metabolites within the endoplasmic reticulum. We describe proteins that maintain MR1 ready for metabolite binding in the endoplasmic reticulum to promote efficient pathogen detection. MR1 thus monitors extracellular microbial metabolites from within the cell.
Hepatitis B virus-like particles access major histocompatibility class I and II antigen presentation pathways in primary dendritic cells
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.VACCINE.2013.02.042
Abstract: Virus-like particles (VLPs) represent high density displays of viral proteins that efficiently trigger immunity. VLPs composed of the small hepatitis B virus envelope protein (HBsAgS) are useful vaccine platforms that induce humoral and cellular immune responses. Notably, however, some studies suggest HBsAgS VLPs impair dendritic cell (DC) function. Here we investigated HBsAgS VLP interaction with DC subsets and antigen access to major histocompatibility complex (MHC) class I and II antigen presentation pathways in primary DCs. HBsAgS VLPs impaired plasmacytoid DC (pDC) interferon alpha (IFNα) production in response to CpG in vitro, but did not alter conventional DC (cDC) or pDC phenotype when administered in vivo. To assess cellular immune responses, HBsAgS VLPs were generated containing the ovalbumin (OVA) model epitopes OVA(257-264) and OVA(323-339) to access MHCI and MHCII antigen presentation pathways, respectively both in vitro and following immunisation in vivo. HBsAgS VLP-OVA(257-264) elicited CTL responses in vivo that were not enhanced by inclusion of an additional MHCII helper epitope. HBsAgS VLP-OVA(257-264) administered in vivo was cross-presented by CD8(+) DCs, but not CD8(-) DCs. Therefore, HBsAgS VLPs can deliver antigen to both MHCI and MHCII antigen presentation pathways in primary DCs and promote cytotoxic and helper T cell priming despite their suppressive effect on pDCs.
Physiological substrates and ontogeny-specific expression of the ubiquitin ligases MARCH1 and MARCH8
Publisher: Elsevier BV
Date: 2021
RNF41 regulates the damage recognition receptor Clec9A and antigen cross-presentation in mouse dendritic cells
Publisher: eLife Sciences Publications, Ltd
Date: 02-12-2020
DOI: 10.7554/ELIFE.63452
Abstract: The dendritic cell receptor Clec9A facilitates processing of dead cell-derived antigens for cross-presentation and the induction of effective CD8 + T cell immune responses. Here, we show that this process is regulated by E3 ubiquitin ligase RNF41 and define a new ubiquitin-mediated mechanism for regulation of Clec9A, reflecting the unique properties of Clec9A as a receptor specialized for delivery of antigens for cross-presentation. We reveal RNF41 is a negative regulator of Clec9A and the cross-presentation of dead cell-derived antigens by mouse dendritic cells. Intriguingly, RNF41 regulates the downstream fate of Clec9A by directly binding and ubiquitinating the extracellular domains of Clec9A. At steady-state, RNF41 ubiquitination of Clec9A facilitates interactions with ER-associated proteins and degradation machinery to control Clec9A levels. However, Clec9A interactions are altered following dead cell uptake to favor antigen presentation. These findings provide important insights into antigen cross-presentation and have implications for development of approaches to modulate immune responses.
Dendritic cell preactivation impairs MHC class II presentation of vaccines and endogenous viral antigens.
Publisher: Proceedings of the National Academy of Sciences
Date: 06-11-2007
Abstract: When dendritic cells (DCs) encounter signals associated with infection or inflammation, they become activated and undergo maturation. Mature DCs are very efficient at presenting antigens captured in association with their activating signal but fail to present subsequently encountered antigens, at least in vitro . Such impairment of MHC class II (MHC II) antigen presentation has generally been thought to be a consequence of down-regulation of endocytosis, so it might be expected that antigens synthesized by the DCs themselves (for instance, viral antigens) would still be presented by mature DCs. Here, we show that DCs matured in vivo could still capture and process soluble antigens, but were unable to present peptides derived from these antigens. Furthermore, presentation of viral antigens synthesized by the DCs themselves was also severely impaired. Indeed, i.v. injection of pathogen mimics, which caused systemic DC activation in vivo , impaired the induction of CD4 T cell responses against subsequently encountered protein antigens. This immunosuppressed state could be reversed by adoptive transfer of DCs loaded exogenously with antigens, demonstrating that impairment of CD4 T cell responses was due to lack of antigen presentation rather than to overt suppression of T cell activation. The biochemical mechanism underlying this phenomenon was the down-regulation of MHC II–peptide complex formation that accompanied DC maturation. These observations have important implications for the design of prophylactic and therapeutic DC vaccines and contribute to the understanding of the mechanisms causing immunosuppression during systemic blood infections.
Ubiquitin-like protein 3 (UBL3) is required for MARCH ubiquitination of major histocompatibility complex class II and CD86
Publisher: Springer Science and Business Media LLC
Date: 11-04-2022
DOI: 10.1038/S41467-022-29524-W
Abstract: The MARCH E3 ubiquitin (Ub) ligase MARCH1 regulates trafficking of major histocompatibility complex class II (MHC II) and CD86, molecules of critical importance to immunity. Here we show, using a genome-wide CRISPR knockout screen, that ubiquitin-like protein 3 (UBL3) is a necessary component of ubiquitination-mediated trafficking of these molecules in mice and in humans. Ubl3 -deficient mice have elevated MHC II and CD86 expression on the surface of professional and atypical antigen presenting cells. UBL3 also regulates MHC II and CD86 in human dendritic cells (DCs) and macrophages. UBL3 impacts ubiquitination of MARCH1 substrates, a mechanism that requires UBL3 plasma membrane anchoring via prenylation. Loss of UBL3 alters adaptive immunity with impaired development of thymic regulatory T cells, loss of conventional type 1 DCs, increased number of trogocytic marginal zone B cells, and defective in vivo MHC II and MHC I antigen presentation. In summary, we identify UBL3 as a conserved, critical factor in MARCH1-mediated ubiquitination with important roles in immune responses.
The cell biology of cross‐presentation and the role of dendritic cell subsets
Publisher: Wiley
Date: 12-02-2008
DOI: 10.1038/ICB.2008.3
Abstract: The cell biology of cross-presentation is reviewed regarding exogenous antigen uptake, antigen degradation and entry into the major histocompatibility complex class I pathway. Whereas cross-presentation is not associated with enhanced phagocytic ability, certain receptors may favour uptake for cross-presentation for ex le mannose receptor for soluble glycoproteins. Perhaps, the defining property of the cross-presenting cell is some specialization in host machinery for handling and transport of antigen across organelles. Both cytosolic and vacuolar pathways are discussed. Which dendritic cell (DC) subset is the cross-presenting cell is explored. Cross-presentation is found within the CD8(+) subset resident in lymphoid organs. The role of other DC subsets (especially the migratory CD8(-) DC) and the route of antigen delivery are also discussed. Further consideration is given to antigen transfer between DC subsets and differential presentation to naive vs memory T cells.
Enhanced survival of lung tissue-resident memory CD8+ T cells during infection with influenza virus due to selective expression of IFITM3
Publisher: Springer Science and Business Media LLC
Date: 27-01-2013
DOI: 10.1038/NI.2525
Abstract: Infection with influenza virus results in the deposition of anti-influenza CD8(+) resident memory T cells (T(RM) cells) in the lung. As a consequence of their location in the lung mucosal tissue, these cells are exposed to cytopathic pathogens over the life of the organism and may themselves be susceptible to infection. Here we found that lung T(RM) cells selectively maintained expression of the interferon-induced transmembrane protein IFITM3, a protein that confers broad resistance to viral infection. Lung T(RM) cells that lacked IFITM3 expression were more susceptible to infection than were their normal counterparts and were selectively lost during a secondary bout of infection. Thus, lung T(RM) cells were programmed to retain IFITM3 expression, which facilitated their survival and protection from viral infection during subsequent exposures.
Unlocking autofluorescence in the era of full spectrum analysis: Implications for immunophenotype discovery projects
Publisher: Wiley
Date: 12-04-2022
DOI: 10.1002/CYTO.A.24555
Abstract: Understanding the complex elements affecting signal resolution in cytometry is key for quality experimental design and data. In this study, we incorporate autofluorescence as a contributing factor to our understanding of resolution in cytometry and corroborate its impact in fluorescence signal detection through mathematical predictions supported by empirical evidence. Our findings illustrate the critical importance of autofluorescence extraction via full spectrum unmixing in unmasking dim signals and delineating the expression and subset distribution of low abundance markers in discovery projects. We apply our findings to the precise definition of the tissue and cellular distribution of a weakly expressed fluorescent protein that reports on a low‐abundance immunological gene. Exploiting the full spectrum coverage enabled by Aurora 5L, we describe a novel approach to the isolation of pure cell subset‐specific autofluorescence profiles based on high dimensionality reduction algorithms. This method can also be used to unveil differences in the autofluorescent fingerprints of tissues in homeostasis and after immunological challenges.
The intracellular pathway for the presentation of vitamin B–related antigens by the antigen-presenting molecule MR1
Publisher: Springer Science and Business Media LLC
Date: 04-04-2016
DOI: 10.1038/NI.3416
Abstract: The antigen-presenting molecule MR1 presents vitamin B-related antigens (VitB antigens) to mucosal-associated invariant T (MAIT) cells through an uncharacterized pathway. We show that MR1, unlike other antigen-presenting molecules, does not constitutively present self-ligands. In the steady state it accumulates in a ligand-receptive conformation within the endoplasmic reticulum. VitB antigens reach this location and form a Schiff base with MR1, triggering a 'molecular switch' that allows MR1-VitB antigen complexes to traffic to the plasma membrane. These complexes are endocytosed with kinetics independent of the affinity of the MR1-ligand interaction and are degraded intracellularly, although some MR1 molecules acquire new ligands during passage through endosomes and recycle back to the surface. MR1 antigen presentation is characterized by a rapid 'off-on-off' mechanism that is strictly dependent on antigen availability.
Organ-specific isoform selection of fatty acid–binding proteins in tissue-resident lymphocytes
Publisher: American Association for the Advancement of Science (AAAS)
Date: 03-04-2020
DOI: 10.1126/SCIIMMUNOL.AAY9283
Abstract: Tissue-resident cells exhibit tissue-specific overlays to the T RM cell residency program that includes flexible FABP isoform selection tailored to the tissue of lodgment.
MAIT cells accumulate in ovarian cancer-elicited ascites where they retain their capacity to respond to MR1 ligands and cytokine cues
Publisher: Springer Science and Business Media LLC
Date: 02-12-2021
DOI: 10.1007/S00262-021-03118-9
Abstract: The low mutational burden of epithelial ovarian cancer (EOC) is an impediment to immunotherapies that rely on conventional MHC-restricted, neoantigen-reactive T lymphocytes. Mucosa-associated invariant T (MAIT) cells are MR1-restricted T cells with remarkable immunomodulatory properties. We sought to characterize intratumoral and ascitic MAIT cells in EOC. Single-cell RNA sequencing of six primary human tumor specimens demonstrated that MAIT cells were present at low frequencies within several tumors. When detectable, these cells highly expressed CD69 and VSIR, but otherwise exhibited a transcriptomic signature inconsistent with overt cellular activation and/or exhaustion. Unlike mainstream CD8
Outside looking in: the inner workings of the crosspresentation pathway within dendritic cells
Publisher: Elsevier BV
Date: 02-2007
Abstract: The entry of exogenous antigen into the MHC class I-restricted cross-presentation pathway can contribute to CD8(+) T cell tolerance and immunity, in particular to peripheral self-antigens or selected viruses and bacteria showing restricted tissue tropism. Dendritic cells are the key cross-presenting cells and, as such, they are thought to carry specialized machinery dedicated to this purpose. Two recent papers describe intracellular components tailored to the dendritic cell cross-presentation pathway.
CD36 family members are TCR-independent ligands for CD1 antigen presenting molecules
Publisher: American Association for the Advancement of Science (AAAS)
Date: 15-06-2021
DOI: 10.1126/SCIIMMUNOL.ABG4176
Abstract: CD1 molecules bind CD36 family members, and blocking this interaction facilitates staining and study of CD1-restricted T cells.
CD69 Does Not Affect the Extent of T Cell Priming
Publisher: Public Library of Science (PLoS)
Date: 30-10-2012
Selective suicide of cross-presenting CD8 + dendritic cells by cytochrome c injection shows functional heterogeneity within this subse
Publisher: Proceedings of the National Academy of Sciences
Date: 26-02-2008
Abstract: Cross-presentation as a fundamental pathway of activating CD8 + T cells has been well established. So far the application of this concept in vivo is limited, and the mechanisms that specialize CD8 + dendritic cells (DCs) for this task are not fully understood. Here we take advantage of the specific cytosolic export feature of cross-presenting DCs together with the property of cytosolic cytochrome c (cyt c ) in initiating Apaf-1-dependent apoptosis selectively in cross-presenting DCs. A single i.v. injection of cyt c in B6 mice produced a 2- to 3-fold reduction in splenic CD8 + DCs but not in Apaf-1-deficient mice. Functional studies both in vivo and in vitro showed that cyt c profoundly abrogated OVA-specific CD8 + T cell proliferation through its apoptosis-inducing effect on cross-presenting DCs. More importantly, in vivo injection of cyt c abolished the induction of cytotoxic T lymphocytes to exogenous antigen and reduced subsequent immunity to tumor challenge. In addition, only a proportion of CD8 + DCs that express abundant IL-12 and Toll-like receptor 3 were efficient cross-presenters. Our data support the hypothesis that cross-presentation in vivo requires cytosolic ersion of endocytosed proteins, conferring cross-presentation specialization to a proportion of CD8 + DCs. We propose that DCs incapable of such transfer, even within the CD8 + DC subset, are unable to cross-present. Our model opens an avenue to specifically target cross-presenting DCs in vivo for manipulating cytotoxic T lymphocyte responses toward infections, tumors, and transplants.
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