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Publisher: Wiley
Date: 12-02-2021
Abstract: Malaria remains a major cause of mortality in the world and an efficient vaccine is the best chance of reducing the disease burden. Vaccination strategies for the liver stage of disease that utilise injection of live radiation‐attenuated sporozoites (RAS) confer sterile immunity, which is mediated by CD8 + memory T cells, with liver‐resident memory T cells (T RM ) being particularly important. We have previously described a TCR transgenic mouse, termed PbT‐I, where all CD8 + T cells recognize a specific peptide from Plasmodium . PbT‐I form liver T RM cells upon RAS injection and are capable of protecting mice against challenge infection. Here, we utilize this transgenic system to examine whether nonliving sporozoites, killed by heat treatment (HKS), could trigger the development of Plasmodium ‐specific liver T RM cells. We found that HKS vaccination induced the formation of memory CD8 + T cells in the spleen and liver, and importantly, liver T RM cells were fewer in number than that induced by RAS. Crucially, we showed the number of T RM cells was significantly higher when HKS were combined with the glycolipid α‐galactosylceramide as an adjuvant. In the future, this work could lead to development of an antimalaria vaccination strategy that does not require live sporozoites, providing greater utility.
Publisher: Elsevier BV
Date: 10-2020
Publisher: Cold Spring Harbor Laboratory
Date: 28-05-2020
DOI: 10.1101/2020.05.28.120808
Abstract: The full ersity of the circulating human B cell compartment is unknown. Flow cytometry analysis suggests that in addition to naïve and memory B cells, there exists a population of CD11c + , CD27 − CD21 − “atypical” B cells, that are associated with chronic or recurrent infection and autoimmunity. We used single cell RNA-seq approaches to examine the ersity of both antigen-specific B cells and total B cells in healthy subjects and in iduals naturally-exposed to recurrent malaria infections. This analysis revealed two B cell lineages: a classical lineage of activated and resting memory B cells, and an atypical-like lineage. Surprisingly, the atypical lineage was common in both malaria exposed in iduals and non-exposed healthy controls. Using barcoded antibodies in conjunction with our transcriptomic data, we found that atypical lineage cells in healthy in iduals lack many atypical B markers and thus represent an undercounted cryptic population. We further determined using antigen specific probes that atypical cells can be induced by primary vaccination in humans and can be recalled upon boosting. Collectively these data suggest that atypical cells are not necessarily pathogenic but can be a normal component of B responses to antigen.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 31-03-2017
DOI: 10.1126/SCIIMMUNOL.AAJ1996
Abstract: LFA-1 expression allows liver-resident CD8 + T cells to patrol hepatic sinusoids yet remain in the liver.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 27-01-2023
DOI: 10.1126/SCIIMMUNOL.ADE7953
Abstract: Interferon regulatory factor 4 (IRF4) is a transcription factor (TF) and key regulator of immune cell development and function. We report a recurrent heterozygous mutation in IRF4, p.T95R, causing an autosomal dominant combined immunodeficiency (CID) in seven patients from six unrelated families. The patients exhibited profound susceptibility to opportunistic infections, notably Pneumocystis jirovecii , and presented with agammaglobulinemia. Patients’ B cells showed impaired maturation, decreased immunoglobulin isotype switching, and defective plasma cell differentiation, whereas their T cells contained reduced T H 17 and T FH populations and exhibited decreased cytokine production. A knock-in mouse model of heterozygous T95R showed a severe defect in antibody production both at the steady state and after immunization with different types of antigens, consistent with the CID observed in these patients. The IRF4 T95R variant maps to the TF’s DNA binding domain, alters its canonical DNA binding specificities, and results in a simultaneous multimorphic combination of loss, gain, and new functions for IRF4. IRF4 T95R behaved as a gain-of-function hypermorph by binding to DNA with higher affinity than IRF4 WT . Despite this increased affinity for DNA, the transcriptional activity on IRF4 canonical genes was reduced, showcasing a hypomorphic activity of IRF4 T95R . Simultaneously, IRF4 T95R functions as a neomorph by binding to noncanonical DNA sites to alter the gene expression profile, including the transcription of genes exclusively induced by IRF4 T95R but not by IRF4 WT . This previously undescribed multimorphic IRF4 pathophysiology disrupts normal lymphocyte biology, causing human disease.
Publisher: American Society for Microbiology
Date: 08-2016
DOI: 10.1128/IAI.00157-16
Abstract: The development of a vaccine is essential for the elimination of malaria. However, despite many years of effort, a successful vaccine has not been achieved. Most subunit vaccine candidates tested in clinical trials have provided limited efficacy, and thus attenuated whole-parasite vaccines are now receiving close scrutiny. Here, we test chemically attenuated Plasmodium yoelii 17X and demonstrate significant protection following homologous and heterologous blood-stage challenge. Protection against blood-stage infection persisted for at least 9 months. Activation of both CD4 + and CD8 + T cells was shown after vaccination however, in vivo studies demonstrated a pivotal role for both CD4 + T cells and B cells since the absence of either cell type led to loss of vaccine-induced protection. In spite of significant activation of circulating CD8 + T cells, liver-stage immunity was not evident. Neither did vaccine-induced CD8 + T cells contribute to blood-stage protection rather, these cells contributed to pathogenesis, since all vaccinated mice depleted of both CD4 + and CD8 + T cells survived a challenge infection. This study provides critical insight into whole-parasite vaccine-induced immunity and strong support for testing whole-parasite vaccines in humans.
Publisher: Frontiers Media SA
Date: 31-01-2022
DOI: 10.3389/FBINF.2021.770448
Abstract: Malaria is a disease caused by Plasmodium parasites, resulting in over 200 million infections and 400,000 deaths every year. A critical step of malaria infection is when sporozoites, injected by mosquitoes, travel to the liver and form liver stages. Malaria vaccine candidates which induce large numbers of malaria-specific CD8 T cells in mice are able to eliminate all liver stages, preventing fulminant malaria. However, how CD8 T cells find all parasites in 48 h of the liver stage lifespan is not well understood. Using intravital microscopy of murine livers, we generated unique data on T cell search for malaria liver stages within a few hours after infection. To detect attraction of T cells to an infection site, we used the von Mises-Fisher distribution in 3D, similar to the 2D von Mises distribution previously used in ecology. Our results suggest that the vast majority (70–95%) of malaria-specific and non-specific liver-localized CD8 T cells did not display attraction towards the infection site, suggesting that the search for malaria liver stages occurs randomly. However, a small fraction (15–20%) displayed weak but detectable attraction towards parasites which already had been surrounded by several T cells. We found that speeds and turning angles correlated with attraction, suggesting that understanding mechanisms that determine the speed of T cell movement in the liver may improve the efficacy of future T cell-based vaccines. Stochastic simulations suggest that a small movement bias towards the parasite dramatically reduces the number of CD8 T cells needed to eliminate all malaria liver stages, but to detect such attraction by in idual cells requires data from long imaging experiments which are not currently feasible. Importantly, as far as we know this is the first demonstration of how activated/memory CD8 T cells might search for the pathogen in nonlymphoid tissues a few hours after infection. We have also established a framework for how attraction of in idual T cells towards a location in 3D can be rigorously evaluated.
Publisher: Springer Science and Business Media LLC
Date: 20-07-2023
Publisher: Elsevier BV
Date: 10-2016
DOI: 10.1016/J.IMMUNI.2016.08.011
Abstract: In recent years, various intervention strategies have reduced malaria morbidity and mortality, but further improvements probably depend upon development of a broadly protective vaccine. To better understand immune requirement for protection, we examined liver-stage immunity after vaccination with irradiated sporozoites, an effective though logistically difficult vaccine. We identified a population of memory CD8
Publisher: Cold Spring Harbor Laboratory
Date: 18-10-2019
DOI: 10.1101/808543
Abstract: Generating sufficient antibody to block infection is a key challenge for vaccines against malaria. Here we show that antibody titres to a key target, the repeat region of the Plasmodium falciparum circumsporozoite protein ( Pf CSP), plateaued after two immunizations in a clinical trial of the radiation-attenuated sporozoite vaccine. To understand the mechanisms limiting vaccine responsiveness, we developed Ig-knockin mice with elevated numbers of Pf CSP-binding B cells. We determined that recall responses were inhibited by antibody feedback via epitope masking of the immunodominant Pf CSP repeat region. Importantly, the amount of antibody that prevents boosting is below the amount of antibody required for protection. Finally, while antibody feedback limited responses to the Pf CSP-repeat region in vaccinated volunteers, potentially protective subdominant responses to C-terminal regions did expand with subsequent boosts. These data suggest that antibody feedback drives the ersification of immune responses and that vaccination for malaria will require the targeting of multiple antigens.
Publisher: The American Association of Immunologists
Date: 04-2021
Abstract: IKZF1 (IKAROS) is essential for normal lymphopoiesis in both humans and mice. Previous Ikzf1 mouse models have demonstrated the dual role for IKZF1 in both B and T cell development and have indicated differential requirements of each zinc finger. Furthermore, mutations in IKZF1 are known to cause common variable immunodeficiency in patients characterized by a loss of B cells and reduced Ab production. Through N-ethyl-N-nitrosourea mutagenesis, we have discovered a novel Ikzf1 mutant mouse with a missense mutation (L132P) in zinc finger 1 (ZF1) located in the DNA binding domain. Unlike other previously reported murine Ikzf1 mutations, this L132P point mutation (Ikzf1L132P) conserves overall protein expression and has a B cell–specific phenotype with no effect on T cell development, indicating that ZF1 is not required for T cells. Mice have reduced Ab responses to immunization and show a progressive loss of serum Igs compared with wild-type littermates. IKZF1L132P overexpressed in NIH3T3 or HEK293T cells failed to localize to pericentromeric heterochromatin and bind target DNA sequences. Coexpression of wild-type and mutant IKZF1, however, allows for localization to pericentromeric heterochromatin and binding to DNA indicating a haploinsufficient mechanism of action for IKZF1L132P. Furthermore, Ikzf1+/L132P mice have late onset defective Ig production, similar to what is observed in common variable immunodeficiency patients. RNA sequencing revealed a total loss of Hsf1 expression in follicular B cells, suggesting a possible functional link for the humoral immune response defects observed in Ikzf1L132P/L132P mice.
Publisher: Frontiers Media SA
Date: 12-04-2022
DOI: 10.3389/FIMMU.2022.825207
Abstract: Upon encountering cognate antigen, B cells can differentiate into short-lived plasmablasts, early memory B cells or germinal center B cells. The factors that determine this fate decision are unclear. Past studies have addressed the role of B cell receptor affinity in this process, but the interplay with other cellular compartments for fate determination is less well understood. Moreover, B cell fate decisions have primarily been studied using model antigens rather than complex pathogen systems, which potentially ignore multifaceted interactions from other cells subsets during infection. Here we address this question using a Plasmodium infection model, examining the response of B cells specific for the immunodominant circumsporozoite protein (CSP). We show that B cell fate is determined in part by the organ environment in which priming occurs, with the majority of the CSP-specific B cell response being derived from splenic plasmablasts. This plasmablast response could occur independent of T cell help, though gamma-delta T cells were required to help with the early isotype switching from IgM to IgG. Interestingly, selective ablation of CD11c + dendritic cells and macrophages significantly reduced the splenic plasmablast response in a manner independent of the presence of CD4 T cell help. Conversely, immunization approaches that targeted CSP-antigen to dendritic cells enhanced the magnitude of the plasmablast response. Altogether, these data indicate that the early CSP-specific response is predominately primed within the spleen and the plasmablast fate of CSP-specific B cells is driven by macrophages and CD11c + dendritic cells.
Publisher: Cold Spring Harbor Laboratory
Date: 15-04-2023
DOI: 10.1101/2023.04.13.536825
Abstract: Long-lived plasma cells (PCs) secrete antibodies that can provide sustained immunity against infection. It has been proposed that high affinity cells are preferentially selected into this compartment, potentiating the immune response. Here we used single cell RNA-seq to track the development of Igh g2A10 cells, specific for the Plasmodium falciparum circumsporozoite protein ( Pf CSP) within the germinal center (GC). We identified cells differentiating into memory B cells (MBC) or PCs and estimated their affinity by V(D)J sequencing. While pre-memory cells were of lower affinity than GC B cells generally, the affinity of pre-PC cells was indistinguishable. Rather, a larger proportion of cells differentiated into PCs in waning GCs. These later emigrants replaced early arrivals in the bone marrow allowing the development of a high affinity PC compartment.
Publisher: Elsevier BV
Date: 02-2021
Publisher: Elsevier BV
Date: 06-2020
Publisher: Cold Spring Harbor Laboratory
Date: 14-09-2020
DOI: 10.1101/2020.09.09.20191031
Abstract: Estimates of seroprevalence of SARS-CoV-2 antibodies have been h ered by inadequate assay sensitivity and specificity. Using an ELISA-based approach to that combines data about IgG responses to both the Nucleocapsid and Spike-receptor binding domain antigens, we show that near-optimal sensitivity and specificity can be achieved. We used this assay to assess the frequency of virus-specific antibodies in a cohort of elective surgery patients in Australia and estimated seroprevalence in Australia to be 0.28% (0 to 0.72%). These data confirm the low level of transmission of SARS-CoV-2 in Australia before July 2020 and validate the specificity of our assay.
Publisher: Cold Spring Harbor Laboratory
Date: 09-11-2021
DOI: 10.1101/2021.11.09.467964
Abstract: Effector and memory CD8+ T cells accumulate in large numbers in the liver where they play key roles in the control of liver pathogens including Plasmodium . It has also been proposed that liver may act as the main place for elimination of effector CD8+ T cells at the resolution of immune responses. Platelets and the integrin LFA-1 have been proposed to be critical for the accumulation of protective CD8+ T cells in the liver conversely, asialo-glycoprotein (ASGP) expression on the surface of CD8+ T cells has been proposed to assist in elimination of effector T cells in the liver. Here we investigated the contributions of these interactions in the accumulation of CD8+ T cells activated in vitro or in vivo by immunization with Plasmodium parasites. Using Mpl -/- mice with constitutive thrombocytopaenia and antibody-mediated platelet depletion models we found that severe reduction in platelet concentration in circulation did not strongly influence the accumulation and protective function of CD8+ T cells in the liver in these models. Surprisingly, inhibition of ASGP receptors did not inhibit the accumulation of effector cells in the liver, but instead prevented these cells from accumulating in the spleen. We further found that enforced expression of ASGP on effector CD8+ T cells using ST3GalI knockout cells lead to their loss from the spleen. These data suggest that platelets play a marginal role in CD8+ T cell function in the liver. Furthermore, ASGP-expressing effector CD8+ T cells are retained in the liver but are lost from the spleen.
Publisher: Cold Spring Harbor Laboratory
Date: 31-07-2022
DOI: 10.1101/2022.07.31.502219
Abstract: A defining feature of successful vaccination is the ability to induce long-lived antigen- specific memory cells. Follicular helper T (Tfh) cells specialize in providing help to B cells in mounting protective humoral immunity in infection and after vaccination. Memory Tfh cells that retain the CXCR5 expression can confer protection through enhancing humoral response upon antigen re-exposure but how they are maintained is poorly understood. CXCR5 + memory Tfh cells in human blood are ided into Tfh1, Tfh2 and Tfh17 cells by the expression of chemokine receptors CXCR3 and CCR6 associated with Th1 and Th17 respectively. Here, we developed a new method to induce Tfh1, Tfh2 and Tfh17-like (iTfh1, iTfh2 and iTfh17) cells in vitro . Although all three iTfh subsets efficiently support antibody responses in recipient mice with immediate immunization, iTfh17 cells are superior to iTfh1 and iTfh2 cells in supporting antibody response to a later immunization after extended resting in vivo to mimic memory maintenance. Notably, the counterpart human Tfh17 cells are selectively enriched in CCR7 + central memory Tfh (Tfh CM ) with survival and proliferative advantages. Furthermore, the analysis of multiple human cohorts that received different vaccines for HBV, influenza virus, tetanus toxin or measles revealed that vaccine-specific Tfh17 cells outcompete Tfh1 or Tfh2 cells for the persistence in memory phase. Therefore, the complementary mouse and human results showing the advantage of Tfh17 cells in maintenance and memory function supports the notion that Tfh17-induced immunization might be preferable in vaccine development to confer long-term protection.
Publisher: Cold Spring Harbor Laboratory
Date: 31-01-2021
DOI: 10.1101/2021.01.29.428877
Abstract: PAX5 is the master transcription factor controlling B cell identity. In humans, mutations in PAX5 account for 30% of B cell acute lymphoblastic leukemia (B-ALL) cases. Investigating the causal effects of PAX5 mutations has however been difficult due to the premature lethality of Pax5 −/− mice. Here we describe a novel mouse strain with a premature STOP mutation in Pax5 (Y351*) that produces a truncated protein and reduction in protein function, yet still allows for some B cell development to occur. A population of uncommitted and multipotent CD19 + B220 − B cells develops in the bone marrow of homozygous mice leading to the development of B-ALL. We show that the tumors frequently acquire secondary mutations in Jak3 , and Ptpn11 highlighting key pathways interacting with PAX5 during malignant transformation. Analysis of the PAX5 Y351* mice provide insight not only into the functional consequence of reduced PAX5 activity on B cell development and identity, but also provides an avenue in which to study PAX5-driven B-ALL in mice. Reduction in PAX5 function in mice induces the development of uncommitted B cells that have multipotent and malignant potential.
Publisher: Wiley
Date: 2021
DOI: 10.1111/ANS.16564
Publisher: Springer International Publishing
Date: 2017
Publisher: eLife Sciences Publications, Ltd
Date: 19-01-2023
DOI: 10.7554/ELIFE.82217
Abstract: A defining feature of successful vaccination is the ability to induce long-lived antigen-specific memory cells. T follicular helper (Tfh) cells specialize in providing help to B cells in mounting protective humoral immunity in infection and after vaccination. Memory Tfh cells that retain the CXCR5 expression can confer protection through enhancing humoral response upon antigen re-exposure but how they are maintained is poorly understood. CXCR5 + memory Tfh cells in human blood are ided into Tfh1, Tfh2, and Tfh17 cells by the expression of chemokine receptors CXCR3 and CCR6 associated with Th1 and Th17, respectively. Here, we developed a new method to induce Tfh1, Tfh2, and Tfh17-like (iTfh1, iTfh2, and iTfh17) mouse cells in vitro. Although all three iTfh subsets efficiently support antibody responses in recipient mice with immediate immunization, iTfh17 cells are superior to iTfh1 and iTfh2 cells in supporting antibody response to a later immunization after extended resting in vivo to mimic memory maintenance. Notably, the counterpart human Tfh17 cells are selectively enriched in CCR7 + central memory Tfh cells with survival and proliferative advantages. Furthermore, the analysis of multiple human cohorts that received different vaccines for HBV, influenza virus, tetanus toxin or measles revealed that vaccine-specific Tfh17 cells outcompete Tfh1 or Tfh2 cells for the persistence in memory phase. Therefore, the complementary mouse and human results showing the advantage of Tfh17 cells in maintenance and memory function supports the notion that Tfh17-induced immunization might be preferable in vaccine development to confer long-term protection.
Publisher: The American Association of Immunologists
Date: 03-2022
Abstract: Pathogen-specific CD8 T cells face the problem of finding rare cells that present their cognate Ag either in the lymph node or in infected tissue. Although quantitative details of T cell movement strategies in some tissues such as lymph nodes or skin have been relatively well characterized, we still lack quantitative understanding of T cell movement in many other important tissues, such as the spleen, lung, liver, and gut. We developed a protocol to generate stable numbers of liver-located CD8 T cells, used intravital microscopy to record movement patterns of CD8 T cells in livers of live mice, and analyzed these and previously published data using well-established statistical and computational methods. We show that, in most of our experiments, Plasmodium-specific liver-localized CD8 T cells perform correlated random walks characterized by transiently superdiffusive displacement with persistence times of 10–15 min that exceed those observed for T cells in lymph nodes. Liver-localized CD8 T cells typically crawl on the luminal side of liver sinusoids (i.e., are in the blood) simulating T cell movement in digital structures derived from the liver sinusoids illustrates that liver structure alone is sufficient to explain the relatively long superdiffusive displacement of T cells. In experiments when CD8 T cells in the liver poorly attach to the sinusoids (e.g., 1 wk after immunization with radiation-attenuated Plasmodium sporozoites), T cells also undergo Lévy flights: large displacements occurring due to cells detaching from the endothelium, floating with the blood flow, and reattaching at another location. Our analysis thus provides quantitative details of movement patterns of liver-localized CD8 T cells and illustrates how structural and physiological details of the tissue may impact T cell movement patterns.
Publisher: Springer Science and Business Media LLC
Date: 07-2017
DOI: 10.1038/NATURE23013
Publisher: Cold Spring Harbor Laboratory
Date: 13-01-2020
DOI: 10.1101/2020.01.12.903682
Abstract: Antibodies targeting the NANP/NVDP repeat domain of the Plasmodium falciparum circumsporozoite protein (CSP Repeat ) can confer protection against malaria. However, it has also been suggested that this repeat domain exists as a decoy that distracts the immune system from mounting protective responses targeting other domains of CSP. Here we show that B cell responses to the repeat domain are indeed ∼10 fold higher than responses to the N- and C-terminal regions of CSP after sporozoite immunization. We investigated the role of the number of CSP Repeat -specific naïve precursor B cells and high avidity binding by B cells in driving the immunodominance of the CSP Repeat . Using adoptive transfer of germline precursors specific for the CSP Repeat , we found that increasing precursor number did indeed increase the responses to the repeat region, but not to the detriment of responses to other epitopes. To investigate the role of avid binding by B cells to the CSP Repeat in driving immunodominance we generated CSP9: a truncated CSP molecule with just 9 NANP repeats. Compared to near full length CSP molecules, CSP9 induced lower BCR signalling in CSP Repeat -specific cells and induced stronger responses to non-repeat epitopes. Finally, we found mice immunized with CSP9 molecules were strongly protected against mosquito bite challenge. Collectively these data demonstrate that the CSP Repeat does function as an immunodominant decoy and that truncated CSP molecules may be a promising avenue for future malaria vaccines. Malaria kills approximately 420,000 in iduals each year(1). Our best vaccine, RTS,S/AS01 is based on the circumsporozoite protein that coasts the surface of the parasite. However, this vaccine is only partially protective. Here we show that responses to a repeat region in the circumsporozoite dominate the immune response. However, immunizing with a circumsporozoite protein with a shortened repeat region induces a more erse immune response, which could be an avenue to make better malaria vaccines.
Publisher: Cold Spring Harbor Laboratory
Date: 15-02-2017
DOI: 10.1101/108746
Abstract: The repeat region of the Plasmodium falciparum circumsporozoite protein (CSP) is a major vaccine antigen because it can be targeted by parasite neutralizing antibodies however, little is known about this interaction. We used isothermal titration calorimetry, X-ray crystallography and mutagenesis-validated modeling to analyze the binding of a murine neutralizing antibody to Plasmodium falciparum CSP. Strikingly, we found that the repeat region of CSP is bound by multiple antibodies. This repeating pattern allows multiple weak interactions of single F AB domains to accumulate and yield a complex with a dissociation constant in the low nM range. Because the CSP protein can potentially cross-link multiple B cell receptors (BCRs) we hypothesized that the B cell response might be T cell independent. However, while there was a modest response in mice deficient in T cell help, the bulk of the response was T cell dependent. By sequencing the BCRs of CSP-repeat specific B cells in inbred mice we found that these cells underwent somatic hypermutation and affinity maturation indicative of a T-dependent response. Last, we found that the BCR repertoire of responding B cells was limited suggesting that the structural simplicity of the repeat may limit the breadth of the immune response. Vaccines aim to protect by inducing the immune system to make molecules called antibodies that can recognize molecules on the surface of invading pathogens. In the case of malaria, our most advanced vaccine candidates aim to promote the production of antibodies that recognize the circumsporozoite protein (CSP) molecule on the surface of the invasive parasite stage called the sporozoite. In this report we use X-ray crystallography to determine the structure of CSP-binding antibodies at the atomic level. We use other techniques such as isothermal titration calorimetry and structural modeling to examine how this antibody interacts with the CSP molecule. Strikingly, we found that each CSP molecule could bind 6 antibodies. This finding has implications for the immune response and may explain why high titers of antibody are needed for protection. Moreover, because the structure of the CSP repeat is quite simple we determined that the number of different kinds of antibodies that could bind this molecule are quite small. However a high avidity interaction between those antibodies and CSP can result from a process called affinity maturation that allows the body to learn how to make improved antibodies specific for pathogen molecules. These data show that while it is challenging for the immune system to recognize and neutralize CSP, it should be possible to generate viable vaccines targeting this molecule.
Publisher: Frontiers Media SA
Date: 22-08-2022
DOI: 10.3389/FIMMU.2022.979060
Abstract: CD11c + T-bet + atypical B cells (ABCs) have been identified in the context of vaccination, acute and chronic infections and autoimmune disease. However, the origins and functions of ABCs remain elusive. A major obstacle in the study of ABCs, and human MBCs more generally, has been the use of different phenotypic markers in different contexts to identify what appear to be phenotypically similar cells. Advances in single-cell RNA sequencing (scRNA-seq) technology have allowed researchers to accurately identify ABCs in different immune contexts such as diseases and tissues. Notably, recent studies utilizing single cell techniques have demonstrated ABCs are a highly conserved memory B cell lineage. This analysis has also revealed that ABCs are more abundant in ostensibly healthy donors than previously thought. Nonetheless, the normal function of these cells remains elusive. In this review, we will focus on scRNA-seq studies to discuss recent advances in our understanding about the development and functions of ABCs.
Publisher: The American Association of Immunologists
Date: 15-06-2022
Abstract: Liver-resident CD8+ T cells can play critical roles in the control of pathogens, including Plasmodium and hepatitis B virus. Paradoxically, it has also been proposed that the liver may act as the main place for the elimination of CD8+ T cells at the resolution of immune responses. We hypothesized that different adhesion processes may drive residence versus elimination of T cells in the liver. Specifically, we investigated whether the expression of asialo-glycoproteins (ASGPs) drives the localization and elimination of effector CD8+ T cells in the liver, while interactions with platelets facilitate liver residence and protective function. Using murine CD8+ T cells activated in vitro, or in vivo by immunization with Plasmodium berghei sporozoites, we found that, unexpectedly, inhibition of ASGP receptors did not inhibit the accumulation of effector cells in the liver, but instead prevented these cells from accumulating in the spleen. In addition, enforced expression of ASGP on effector CD8+ T cells using St3GalI-deficient cells lead to their loss from the spleen. We also found, using different mouse models of thrombocytopenia, that severe reduction in platelet concentration in circulation did not strongly influence the residence and protective function of CD8+ T cells in the liver. These data suggest that platelets play a marginal role in CD8+ T cell function in the liver. Furthermore, ASGP-expressing effector CD8+ T cells accumulate in the spleen, not the liver, prior to their destruction.
Publisher: Springer Science and Business Media LLC
Date: 16-02-2017
DOI: 10.1038/NCOMMS14455
Abstract: Apicomplexans are obligate intracellular parasites that scavenge essential nutrients from their hosts via transporter proteins on their plasma membrane. The identities of the transporters that mediate amino acid uptake into apicomplexans are unknown. Here we demonstrate that members of an apicomplexan-specific protein family—the Novel Putative Transporters (NPTs)—play key roles in the uptake of cationic amino acids. We show that an NPT from Toxoplasma gondii ( Tg NPT1) is a selective arginine transporter that is essential for parasite survival and virulence. We also demonstrate that a homologue of Tg NPT1 from the malaria parasite Plasmodium berghei ( Pb NPT1), shown previously to be essential for the sexual gametocyte stage of the parasite, is a cationic amino acid transporter. This reveals a role for cationic amino acid scavenging in gametocyte biology. Our study demonstrates a critical role for amino acid transporters in the survival, virulence and life cycle progression of these parasites.
Publisher: Wiley
Date: 06-02-2017
Abstract: Commercial microscopy systems make use of tandem scanning i.e. either slow or fast scanning. We constructed, for the first time, an advanced control system capable of delivering a dynamic line scanning speed ranging from 2.7 kHz to 27 kHz and achieve variable frame rates from 5 Hz to 50 Hz (512 × 512). The dynamic scanning ability is digitally controlled by a new customized open-source software named PScan1.0. This permits manipulation of scanning rates either to gain higher fluorescence signal at slow frame rate without increasing laser power or increase frame rates to capture high speed events. By adjusting imaging speed from 40 Hz to 160 Hz, we capture a range of calcium waves and transient peaks from soma and dendrite of single fluorescence neuron (CAL-520AM). Motion artifacts arising from respiratory and cardiac motion in small animal imaging reduce quality of real-time images of single cells in-vivo. An image registration algorithm, integrated with PScan1.0, was shown to perform both real time and post-processed motion correction. The improvement is verified by quantification of blood flow rates. This work describes all the steps necessary to develop a high performance and flexible polygon-mirror based multiphoton microscope system for in-vivo biological imaging.
Publisher: Elsevier BV
Date: 10-2019
Publisher: Public Library of Science (PLoS)
Date: 31-07-2017
Publisher: Elsevier BV
Date: 11-2022
Abstract: Protective antibodies against Plasmodium falciparum merozoite antigens, including EBA-175, can inhibit erythrocyte invasion. New data from Musasia et al. indicate that these antibodies can also trigger antibody-dependent phagocytosis of ring-infected and uninfected erythrocytes and that this correlates with protection from malaria. This provides a new pathway for vaccine design.
Publisher: Cold Spring Harbor Laboratory
Date: 02-09-2022
DOI: 10.1101/2022.09.01.506173
Abstract: CD11c + atypical B cells (ABC) are an alternative memory B cell lineage identified both in normal immune responses as well as pathogenic responses in autoimmunity. While it is clear that ABCs have a distinct transcriptional program, the factors that direct this program have not been identified. Here, we generated a human tonsil single-cell RNA-seq dataset and identified candidate transcription factors associated with the ABC population. We selected 8 of these transcription factors for further analysis based on their conserved expression in mouse ABC bulk RNA-seq datasets. Using an optimized CRSPR-Cas9 knockdown method we found that only zinc finger E-box binding homeobox 2 ( Zeb2 ) knock-out impaired ABC formation. To assess the role of Zeb2 in ABC formation in vivo we used Zeb2 fl/fl mice crossed to a CD23 Cre line. Germinal center and plasma cell responses in these mice after Plasmodium sporozoite immunization were largely unaltered but we observed a specific defect in ABC formation. We further determined that ZEB2 haploinsufficient Mowat Wilson syndrome patients also have decreased circulating ABCs in the blood, supporting a role for this transcription factor in humans as well as mice. In sum, we identified Zeb2 as a key TF governing the formation of ABCs.
Publisher: Elsevier BV
Date: 04-2021
Publisher: Oxford University Press (OUP)
Date: 03-10-2021
Abstract: Estimates of seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies have been h ered by inadequate assay sensitivity and specificity. Using an enzyme-linked immunosorbent assay–based approach that combines data about immunoglobulin G responses to both the nucleocapsid and spike receptor binding domain antigens, we show that excellent sensitivity and specificity can be achieved. We used this assay to assess the frequency of virus-specific antibodies in a cohort of elective surgery patients in Australia and estimated seroprevalence in Australia to be 0.28% (95% Confidence Interval, 0–1.15%). These data confirm the low level of transmission of SARS-CoV-2 in Australia before July 2020 and validate the specificity of our assay.
No related organisations have been discovered for Ian Cockburn.
Start Date: 03-2015
End Date: 12-2018
Amount: $560,000.00
Summary: A novel family of amino acid transporters in Apicomplexan parasites. Apicomplexan parasites are single celled organisms that are the causative agents of major diseases in livestock and humans. However, the basic biochemistry of these intracellular parasites is poorly understood, and there are limited treatments available for the diseases these parasites cause. The project hypothesis is that a novel family of proteins that are unique to apicomplexan parasites play a key role in the uptake of esse .... A novel family of amino acid transporters in Apicomplexan parasites. Apicomplexan parasites are single celled organisms that are the causative agents of major diseases in livestock and humans. However, the basic biochemistry of these intracellular parasites is poorly understood, and there are limited treatments available for the diseases these parasites cause. The project hypothesis is that a novel family of proteins that are unique to apicomplexan parasites play a key role in the uptake of essential nutrients (amino acids) into these organisms. This project aims to use a combination of genetic, biochemical and physiological methods to understand the function of these proteins, the role(s) that they play in apicomplexan biology, and their importance for parasite survival. Read more Read less
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2022
End Date: 05-2025
Amount: $474,000.00
Summary: RNA-binding proteins rewire transcriptomes in immune cell differentiation. This project aims to combine advanced computational and experimental techniques to investigate a new layer of gene regulation by novel RNA binding proteins (RBP) which control messenger RNA length in immune cells. This project expects to demonstrate that these RBPs have a profound effect on immune cell differentiation and response to infection. Expected outcomes include the discovery of new RBPs regulating immunity, with .... RNA-binding proteins rewire transcriptomes in immune cell differentiation. This project aims to combine advanced computational and experimental techniques to investigate a new layer of gene regulation by novel RNA binding proteins (RBP) which control messenger RNA length in immune cells. This project expects to demonstrate that these RBPs have a profound effect on immune cell differentiation and response to infection. Expected outcomes include the discovery of new RBPs regulating immunity, with mechanism and function determined by novel CRISPR editing of a transgenic mouse model. The significant benefit will be a more complete understanding of RNA mechanisms of immune response, which will be critical in informing future advances in the rapidly developing areas of RNA-based biotechnologies and synthetic immunology. Read more Read less
Funder: Australian Research Council
View Funded Activity