The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Vasilis Kosmoliaptsis - One of the best experts on this subject based on the ideXlab platform.
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germinal center Alloantibody responses mediate progression of chronic allograft injury
Frontiers in Immunology, 2019Co-Authors: Manu Chhabra, Vasilis Kosmoliaptsis, Jason M. Ali, Jawaher Alsughayyir, Saeed M Qureshi, Mekhola Mallik, Ivonne Gamper, E Moseley, Sarah Peacock, Martin GoddardAbstract:Different profiles of Alloantibody responses are observed in the clinic, with those that persist, often despite targeted treatment, associated with poorer long-term transplant outcomes. Although such responses would suggest an underlying germinal centre (GC) response, the relationship to cellular events within the allospecific B cell population is unclear. Here we examine the contribution of germinal centre (GC) humoral alloimmunity to chronic antibody mediated rejection (AMR). A murine model of chronic AMR was developed in which T cell deficient (Tcrbd−/−) C57BL/6 recipients were challenged with MHC-mismatched BALB/c heart allografts and T cell help provided by reconstituting with 103 ‘TCR75’ CD4 T cells that recognise self-restricted allopeptide derived from the H-2Kd MHC class I alloantigen. Reconstituted recipients developed Ig-switched anti-Kd Alloantibody responses that were slow to develop, but long-lived, with confocal immunofluorescence and flow cytometric characterisation of responding H-2Kd-allospecific B cells confirming persistent splenic GC activity. This was associated with T follicular helper (TFH) cell differentiation of the transferred TCR75 CD4 T cells. Heart grafts developed progressive allograft vasculopathy, and were rejected chronically (MST 50 days), with explanted allografts displaying features of humoral vascular rejection. Critically, late Alloantibody responses were abolished, and heart grafts survived indefinitely, in recipients reconstituted with Sh2d1a−/− TCR75 CD4 T cells that were genetically incapable of providing TFH cell function. The GC response was associated with affinity maturation of the anti-Kd Alloantibody response, and its contribution to progression of allograft vasculopathy related principally to secretion of Alloantibody, rather than to enhanced alloreactive T cell priming, because grafts survived long-term when B cells could present alloantigen, but not secrete Alloantibody. Similarly, sera sampled at late time points from chronically-rejecting recipients induced more vigorous donor endothelial responses in vitro than sera sampled earlier after transplantation. In summary, our results suggest that chronic AMR and progression of allograft vasculopathy is dependent upon allospecific GC activity, with critical help provided by TFH cells. Clinical strategies that target the TFH cell subset may hold therapeutic potential.
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relative frequencies of alloantigen specific helper cd4 t cells and b cells determine mode of antibody mediated allograft rejection
Frontiers in Immunology, 2019Co-Authors: Jawaher Alsughayyir, Vasilis Kosmoliaptsis, Manu Chhabra, Saeed M Qureshi, Mekhola Mallik, Ivonne Gamper, E Moseley, Sarah Peacock, Martin Goddard, Michelle A LintermanAbstract:Humoral alloimmunity is now recognised as a major determinant of transplant outcome, but the nature of the T cell alloresponse that underpins Alloantibody generation remains poorly understood. Here, we examine how the relative frequencies of alloantigen-specific B cells and helper CD4 T cells influence the humoral alloimmune response and how this relates to antibody-mediated rejection (AMR). An MHC-mismatched murine model of cardiac AMR was developed, in which T cell help for Alloantibody responses in T cell deficient (Tcrbd−/−) C57BL/6 recipients against donor H-2Kd MHC class I alloantigen was provided by adoptively transferred ‘TCR75’ CD4 T cells that recognise processed H-2Kd allopeptide via the indirect-pathway. Transfer of large numbers (5 x 105) of TCR75 CD4 T cells was associated with rapid development of robust class-switched anti-H-2Kd humoral alloimmunity and BALB/c heart grafts were rejected promptly (MST 9 days). Grafts were not rejected in T and B cell deficient Rag2-/- recipients that were reconstituted with TCR75 CD4 T cells or in control (non-reconstituted) Tcrbd−/− recipients, suggesting that the transferred TCR75 CD4 T cells were mediating graft rejection principally by providing help for effector Alloantibody responses. In support, acutely rejecting BALB/c heart grafts exhibited hallmark features of acute AMR, with widespread complement C4d deposition, whereas cellular rejection was not evident. In addition, passive transfer of immune serum from rejecting mice to Rag2−/− recipients resulted in eventual BALB/c heart allograft rejection (MST 20 days). Despite being long-lived, the Alloantibody responses observed at rejection of the BALB/c heart grafts were predominantly generated by extrafollicular foci. Rapid graft rejection still occurred when recipients were reconstituted with similar numbers of Sh2d1a−/− TCR75 CD4 T cells that are incapable of providing T follicular helper cell function for generating GC alloimmunity. Similarly, Alloantibody responses generated in Tcrbd−/− recipients reconstituted with smaller number of wild-type TCR75 CD4 T cells (10^3), although long-lasting, did not have a discernible extrafollicular component, and grafts were rejected much more slowly (MST 50 days). In summary, a relative abundance of helper CD4 T cells favours development of strong extrafollicular Alloantibody responses that mediate acute humoral rejection, without requirement for GC activity.
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Table_1_Relative Frequencies of Alloantigen-Specific Helper CD4 T Cells and B Cells Determine Mode of Antibody-Mediated Allograft Rejection.docx
2019Co-Authors: Jawaher Alsughayyir, Vasilis Kosmoliaptsis, Jason M. Ali, Manu Chhabra, Saeed M Qureshi, Mekhola Mallik, Ivonne Gamper, Sarah Peacock, Ellen L. Moseley, Martin J. GoddardAbstract:Humoral alloimmunity is now recognized as a major determinant of transplant outcome. MHC glycoprotein is considered a typical T-dependent antigen, but the nature of the T cell alloresponse that underpins Alloantibody generation remains poorly understood. Here, we examine how the relative frequencies of alloantigen-specific B cells and helper CD4 T cells influence the humoral alloimmune response and how this relates to antibody-mediated rejection (AMR). An MHC-mismatched murine model of cardiac AMR was developed, in which T cell help for Alloantibody responses in T cell deficient (Tcrbd−/−) C57BL/6 recipients against donor H-2Kd MHC class I alloantigen was provided by adoptively transferred “TCR75” CD4 T cells that recognize processed H-2Kd allopeptide via the indirect-pathway. Transfer of large numbers (5 × 105) of TCR75 CD4 T cells was associated with rapid development of robust class-switched anti-H-2Kd humoral alloimmunity and BALB/c heart grafts were rejected promptly (MST 9 days). Grafts were not rejected in T and B cell deficient Rag2−/− recipients that were reconstituted with TCR75 CD4 T cells or in control (non-reconstituted) Tcrbd−/− recipients, suggesting that the transferred TCR75 CD4 T cells were mediating graft rejection principally by providing help for effector Alloantibody responses. In support, acutely rejecting BALB/c heart grafts exhibited hallmark features of acute AMR, with widespread complement C4d deposition, whereas cellular rejection was not evident. In addition, passive transfer of immune serum from rejecting mice to Rag2−/− recipients resulted in eventual BALB/c heart allograft rejection (MST 20 days). Despite being long-lived, the Alloantibody responses observed at rejection of the BALB/c heart grafts were predominantly generated by extrafollicular foci: splenic germinal center (GC) activity had not yet developed; IgG secreting cells were confined to the splenic red pulp and bridging channels; and, most convincingly, rapid graft rejection still occurred when recipients were reconstituted with similar numbers of Sh2d1a−/− TCR75 CD4 T cells that are genetically incapable of providing T follicular helper cell function for generating GC alloimmunity. Similarly, Alloantibody responses generated in Tcrbd−/− recipients reconstituted with smaller number of wild-type TCR75 CD4 T cells (103), although long-lasting, did not have a discernible extrafollicular component, and grafts were rejected much more slowly (MST 50 days). By modeling antibody responses to Hen Egg Lysozyme protein, we confirm that a high ratio of antigen-specific helper T cells to B cells favors development of the extrafollicular response, whereas GC activity is favored by a relatively high ratio of B cells. In summary, a relative abundance of helper CD4 T cells favors development of strong extrafollicular Alloantibody responses that mediate acute humoral rejection, without requirement for GC activity.This work is composed of two parts, of which this is Part I. Please read also Part II: Chhabra et al., 2019.
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Image_2_Relative Frequencies of Alloantigen-Specific Helper CD4 T Cells and B Cells Determine Mode of Antibody-Mediated Allograft Rejection.TIFF
2019Co-Authors: Jawaher Alsughayyir, Vasilis Kosmoliaptsis, Jason M. Ali, Manu Chhabra, Saeed M Qureshi, Mekhola Mallik, Ivonne Gamper, Sarah Peacock, Ellen L. Moseley, Martin J. GoddardAbstract:Humoral alloimmunity is now recognized as a major determinant of transplant outcome. MHC glycoprotein is considered a typical T-dependent antigen, but the nature of the T cell alloresponse that underpins Alloantibody generation remains poorly understood. Here, we examine how the relative frequencies of alloantigen-specific B cells and helper CD4 T cells influence the humoral alloimmune response and how this relates to antibody-mediated rejection (AMR). An MHC-mismatched murine model of cardiac AMR was developed, in which T cell help for Alloantibody responses in T cell deficient (Tcrbd−/−) C57BL/6 recipients against donor H-2Kd MHC class I alloantigen was provided by adoptively transferred “TCR75” CD4 T cells that recognize processed H-2Kd allopeptide via the indirect-pathway. Transfer of large numbers (5 × 105) of TCR75 CD4 T cells was associated with rapid development of robust class-switched anti-H-2Kd humoral alloimmunity and BALB/c heart grafts were rejected promptly (MST 9 days). Grafts were not rejected in T and B cell deficient Rag2−/− recipients that were reconstituted with TCR75 CD4 T cells or in control (non-reconstituted) Tcrbd−/− recipients, suggesting that the transferred TCR75 CD4 T cells were mediating graft rejection principally by providing help for effector Alloantibody responses. In support, acutely rejecting BALB/c heart grafts exhibited hallmark features of acute AMR, with widespread complement C4d deposition, whereas cellular rejection was not evident. In addition, passive transfer of immune serum from rejecting mice to Rag2−/− recipients resulted in eventual BALB/c heart allograft rejection (MST 20 days). Despite being long-lived, the Alloantibody responses observed at rejection of the BALB/c heart grafts were predominantly generated by extrafollicular foci: splenic germinal center (GC) activity had not yet developed; IgG secreting cells were confined to the splenic red pulp and bridging channels; and, most convincingly, rapid graft rejection still occurred when recipients were reconstituted with similar numbers of Sh2d1a−/− TCR75 CD4 T cells that are genetically incapable of providing T follicular helper cell function for generating GC alloimmunity. Similarly, Alloantibody responses generated in Tcrbd−/− recipients reconstituted with smaller number of wild-type TCR75 CD4 T cells (103), although long-lasting, did not have a discernible extrafollicular component, and grafts were rejected much more slowly (MST 50 days). By modeling antibody responses to Hen Egg Lysozyme protein, we confirm that a high ratio of antigen-specific helper T cells to B cells favors development of the extrafollicular response, whereas GC activity is favored by a relatively high ratio of B cells. In summary, a relative abundance of helper CD4 T cells favors development of strong extrafollicular Alloantibody responses that mediate acute humoral rejection, without requirement for GC activity.This work is composed of two parts, of which this is Part I. Please read also Part II: Chhabra et al., 2019.
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Relative Frequencies of Alloantigen-Specific Helper CD4 T Cells and B Cells Determine Mode of Antibody-Mediated Allograft Rejection
Frontiers Media S.A., 2019Co-Authors: Jawaher Alsughayyir, Vasilis Kosmoliaptsis, Jason M. Ali, Manu Chhabra, Saeed M Qureshi, Mekhola Mallik, Ivonne Gamper, Sarah Peacock, Ellen L. Moseley, Martin J. GoddardAbstract:Humoral alloimmunity is now recognized as a major determinant of transplant outcome. MHC glycoprotein is considered a typical T-dependent antigen, but the nature of the T cell alloresponse that underpins Alloantibody generation remains poorly understood. Here, we examine how the relative frequencies of alloantigen-specific B cells and helper CD4 T cells influence the humoral alloimmune response and how this relates to antibody-mediated rejection (AMR). An MHC-mismatched murine model of cardiac AMR was developed, in which T cell help for Alloantibody responses in T cell deficient (Tcrbd−/−) C57BL/6 recipients against donor H-2Kd MHC class I alloantigen was provided by adoptively transferred “TCR75” CD4 T cells that recognize processed H-2Kd allopeptide via the indirect-pathway. Transfer of large numbers (5 × 105) of TCR75 CD4 T cells was associated with rapid development of robust class-switched anti-H-2Kd humoral alloimmunity and BALB/c heart grafts were rejected promptly (MST 9 days). Grafts were not rejected in T and B cell deficient Rag2−/− recipients that were reconstituted with TCR75 CD4 T cells or in control (non-reconstituted) Tcrbd−/− recipients, suggesting that the transferred TCR75 CD4 T cells were mediating graft rejection principally by providing help for effector Alloantibody responses. In support, acutely rejecting BALB/c heart grafts exhibited hallmark features of acute AMR, with widespread complement C4d deposition, whereas cellular rejection was not evident. In addition, passive transfer of immune serum from rejecting mice to Rag2−/− recipients resulted in eventual BALB/c heart allograft rejection (MST 20 days). Despite being long-lived, the Alloantibody responses observed at rejection of the BALB/c heart grafts were predominantly generated by extrafollicular foci: splenic germinal center (GC) activity had not yet developed; IgG secreting cells were confined to the splenic red pulp and bridging channels; and, most convincingly, rapid graft rejection still occurred when recipients were reconstituted with similar numbers of Sh2d1a−/− TCR75 CD4 T cells that are genetically incapable of providing T follicular helper cell function for generating GC alloimmunity. Similarly, Alloantibody responses generated in Tcrbd−/− recipients reconstituted with smaller number of wild-type TCR75 CD4 T cells (103), although long-lasting, did not have a discernible extrafollicular component, and grafts were rejected much more slowly (MST 50 days). By modeling antibody responses to Hen Egg Lysozyme protein, we confirm that a high ratio of antigen-specific helper T cells to B cells favors development of the extrafollicular response, whereas GC activity is favored by a relatively high ratio of B cells. In summary, a relative abundance of helper CD4 T cells favors development of strong extrafollicular Alloantibody responses that mediate acute humoral rejection, without requirement for GC activity.This work is composed of two parts, of which this is Part I. Please read also Part II: Chhabra et al., 2019
Andrew J Bradley - One of the best experts on this subject based on the ideXlab platform.
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predicting humoral alloimmunity from differences in donor and recipient hla surface electrostatic potential
Journal of Immunology, 2018Co-Authors: Craig J Taylor, Andrew J Bradley, Dermot Mallon, Christiane Kling, Matthew Robb, Eva Ellinghaus, Dieter Kabelitz, Vasilis KosmoliaptsisAbstract:In transplantation, development of humoral alloimmunity against donor HLA is a major cause of organ transplant failure, but our ability to assess the immunological risk associated with a potential donor–recipient HLA combination is limited. We hypothesized that the capacity of donor HLA to induce a specific Alloantibody response depends on their structural and physicochemical dissimilarity compared with recipient HLA. To test this hypothesis, we first developed a novel computational scoring system that enables quantitative assessment of surface electrostatic potential differences between donor and recipient HLA molecules at the tertiary structure level [three-dimensional electrostatic mismatch score (EMS-3D)]. We then examined humoral alloimmune responses in healthy females subjected to a standardized injection of donor lymphocytes from their male partner. This analysis showed a strong association between the EMS-3D of donor HLA and donor-specific Alloantibody development; this relationship was strongest for HLA-DQ alloantigens. In the clinical transplantation setting, the immunogenic potential of HLA-DRB1 and -DQ mismatches expressed on donor kidneys, as assessed by their EMS-3D, was an independent predictor of development of donor-specific Alloantibody after graft failure. Collectively, these findings demonstrate the translational potential of our approach to improve immunological risk assessment and to decrease the burden of humoral alloimmunity in organ transplantation.
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predicting humoral alloimmunity from differences in donor recipient hla surface electrostatic potential
bioRxiv, 2018Co-Authors: Dermot Mallon, Craig J Taylor, Andrew J Bradley, Christiane Kling, Matthew Robb, Eva Ellinghaus, Dieter Kabelitz, Vasilis KosmoliaptsisAbstract:In transplantation, development of humoral alloimmunity against donor HLA is a major cause of organ transplant failure but our ability to assess the immunological risk associated with a potential donor-recipient HLA combination is limited. We hypothesised that the capacity of donor HLA to induce a specific Alloantibody response depends on their structural and physicochemical dissimilarity compared to recipient HLA. To test this hypothesis, we first developed a novel computational scoring system that enables quantitative assessment of surface electrostatic potential differences between donor and recipient HLA molecules at the tertiary structure level (electrostatic mismatch score-three dimensional; EMS-3D). We then examined humoral alloimmune responses in healthy females subjected to a standardised injection of donor lymphocytes from their male partner. This analysis showed a strong association between the EMS-3D of donor HLA and donor-specific Alloantibody development; this relationship was strongest for HLA-DQ alloantigens. In the clinical transplantation setting, the immunogenic potential of HLA-DRB1 and -DQ mismatches expressed on donor kidneys, as assessed by their EMS-3D, was an independent predictor of development of donor-specific Alloantibody after graft failure. Collectively, these findings demonstrate the translational potential of our approach to improve immunological risk assessment and to decrease the burden of humoral alloimmunity in organ transplantation.
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recipient natural killer cell allorecognition of passenger donor lymphocytes and its effect on adaptive alloimmunity after transplantation
The Lancet, 2015Co-Authors: I Harper, Eleanor M Bolton, Andrew J Bradley, G J PettigrewAbstract:Abstract Background Memory T cells are known to reside in peripheral non-lymphoid tissue, but how their presence within solid organ allografts affects transplant outcomes is not known. We have previously described how graft-versus-host (GVH) allorecognition by passenger CD4 T cells within MHC class II-mismatched bm12 heart grafts provokes antinuclear humoral autoimmunity in C57BL/6 recipient mice. Here we aimed to examine how such GVH recognition affects the alloresponse to allografts with greater mismatching. Methods A MHC class I and II mismatched murine model of cardiac transplantation was developed (bm12.Kd.IE to C57BL/6). After transplantation, cellular and humoral responses against mismatched antigens were measured with ELISPOT and ELISA, and the effect of GVH recognition assessed by depletion of donor CD4 T cells before graft procurement. Antinuclear autoantibody development was assessedwith HeP-2 indirect immunofluorescence. The role of recipient natural killer (NK) cells was examined by depletion with anti-NK1.1 antibody. Findings Bm12.Kd.IE heart grafts provoked strong germinal centre Alloantibody and autoantibody responses in C57BL/6 recipients and developed allograft vasculopathy. By contrast, heart grafts from CD4 T-cell-depleted donors developed only minimal vasculopathy, and the Alloantibody responses were weaker, without observable autoantibody. Bm12.Kd.IE CD4 T cells survived long term when transferred to RAG hosts suggesting that avoidance of killing by host NK cells might be essential for autoantibody development. In support, in a model of Alloantibody-mediated vasculopathy, depletion of NK cells from a C57BL/6 recipient of a BALB/c heart graft resulted in the development of autoantibody, amplification of the Alloantibody response, and rapid allograft rejection. This amplification was abrogated by depletion of donor CD4 T cells. Interpretation Although host adaptive immunity is expected to bring about destruction of passenger lymphocytes within heart allografts, this process occurs too slowly to prevent GVH-mediated augmentation of the alloresponse to the graft. Rather, rapid killing of donor lymphocytes by host alloreactive NK cells is essential. Passenger CD4 lymphocytes might therefore contribute to chronic rejection in recipients receiving an allograft that does not prompt innate NK cell recognition. Funding Wellcome Trust Clinical Research Training Fellowship.
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three dimensional structural modelling and calculation of electrostatic potentials of hla bw4 and bw6 epitopes to explain the molecular basis for Alloantibody binding toward predicting hla antigenicity and immunogenicity
Transplantation, 2015Co-Authors: Dermot Mallon, Andrew J Bradley, Craig J Taylor, Peter J Winn, Vasilis KosmoliaptsisAbstract:BackgroundWe have previously shown that qualitative assessment of surface electrostatic potential of HLA class I molecules helps explain serological patterns of Alloantibody binding. We have now used a novel computational approach to quantitate differences in surface electrostatic potential of HLA B
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allorecognition pathways in transplant rejection and tolerance
Transplantation, 2013Co-Authors: Eleanor M Bolton, Andrew J Bradley, Gavin J. PettigrewAbstract:With the advent of cellular therapies, it has become clear that the success of future therapies in prolonging allograft survival will require an intimate understanding of the allorecognition pathways and effector mechanisms that are responsible for chronic rejection and late graft loss. Here, we consider current understanding of T-cell allorecognition pathways and discuss the most likely mechanisms by which these pathways collaborate with other effector mechanisms to cause allograft rejection. We also consider how this knowledge may inform development of future strategies to prevent allograft rejection. Although both direct and indirect pathway CD4 T cells appear active immediately after transplantation, it has emerged that indirect pathway CD4 T cells are likely to be the dominant alloreactive T-cell population late after transplantation. Their ability to provide help for generating long-lived Alloantibody is likely one of the main mechanisms responsible for the progression of allograft vasculopathy and chronic rejection. Recent work has suggested that regulatory T cells may be an effective cellular therapy in transplantation. Given the above, adoptive therapy with CD4 regulatory T cells with indirect allospecificity is a rational first choice in attempting to attenuate the development and progression of chronic rejection; those with additional properties that enable inhibition of germinal center Alloantibody responses hold particular appeal.
Ginny L. Bumgardner - One of the best experts on this subject based on the ideXlab platform.
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antibody suppressor cd8 t cells require cxcr5
Transplantation, 2019Co-Authors: Jason M Zimmerer, Bryce A Ringwald, Steven M Elzein, Christina L Avila, Robert T Warren, Mahmoud Abdelrasoul, Ginny L. BumgardnerAbstract:BACKGROUND We previously reported the novel activity of alloprimed CD8 T cells that suppress posttransplant Alloantibody production. The purpose of the study is to investigate the expression and role of CXCR5 on antibody-suppressor CD8 T-cell function. METHODS C57BL/6 mice were transplanted with FVB/N hepatocytes. Alloprimed CD8 T cells were retrieved on day 7 from hepatocyte transplant recipients. Unsorted or flow-sorted (CXCR5CXCR3 and CXCR3CXCR5) alloprimed CD8 T-cell subsets were analyzed for in vitro cytotoxicity and capacity to inhibit in vivo Alloantibody production following adoptive transfer into C57BL/6 or high Alloantibody-producing CD8 knock out (KO) hepatocyte transplant recipients. Alloantibody titer was assessed in CD8 KO mice reconstituted with naive CD8 T cells retrieved from C57BL/6, CXCR5 KO, or CXCR3 KO mice. Antibody suppression by ovalbumin (OVA)-primed monoclonal OVA-specific t-cell receptor transgenic CD8+ T cells (OT-I) CXCR5 or CXCR3 CD8 T-cell subsets was also investigated. RESULTS Alloprimed CXCR5CXCR3CD8 T cells mediated in vitro cytotoxicity of alloprimed "self" B cells, while CXCR3CXCR5CD8 T cells did not. Only flow-sorted alloprimed CXCR5CXCR3CD8 T cells (not flow-sorted alloprimed CXCR3CXCR5CD8 T cells) suppressed Alloantibody production and enhanced graft survival when transferred into transplant recipients. Unlike CD8 T cells from wild-type or CXCR3 KO mice, CD8 T cells from CXCR5 KO mice do not develop Alloantibody-suppressor function. Similarly, only flow-sorted CXCR5CXCR3 (and not CXCR3CXCR5) OVA-primed OT-I CD8 T cells mediated in vivo suppression of anti-OVA antibody production. CONCLUSIONS These data support the conclusion that expression of CXCR5 by antigen-primed CD8 T cells is critical for the function of antibody-suppressor CD8 T cells.
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antibody suppressor cd8 t cells require cxcr5
Transplantation, 2019Co-Authors: Jason M Zimmerer, Bryce A Ringwald, Steven M Elzein, Christina L Avila, Robert T Warren, Mahmoud Abdelrasoul, Ginny L. BumgardnerAbstract:BACKGROUND We previously reported the novel activity of alloprimed CD8 T cells that suppress posttransplant Alloantibody production. The purpose of the study is to investigate the expression and role of CXCR5 on antibody-suppressor CD8 T-cell function. METHODS C57BL/6 mice were transplanted with FVB/N hepatocytes. Alloprimed CD8 T cells were retrieved on day 7 from hepatocyte transplant recipients. Unsorted or flow-sorted (CXCR5CXCR3 and CXCR3CXCR5) alloprimed CD8 T-cell subsets were analyzed for in vitro cytotoxicity and capacity to inhibit in vivo Alloantibody production following adoptive transfer into C57BL/6 or high Alloantibody-producing CD8 knock out (KO) hepatocyte transplant recipients. Alloantibody titer was assessed in CD8 KO mice reconstituted with naive CD8 T cells retrieved from C57BL/6, CXCR5 KO, or CXCR3 KO mice. Antibody suppression by ovalbumin (OVA)-primed monoclonal OVA-specific t-cell receptor transgenic CD8+ T cells (OT-I) CXCR5 or CXCR3 CD8 T-cell subsets was also investigated. RESULTS Alloprimed CXCR5CXCR3CD8 T cells mediated in vitro cytotoxicity of alloprimed "self" B cells, while CXCR3CXCR5CD8 T cells did not. Only flow-sorted alloprimed CXCR5CXCR3CD8 T cells (not flow-sorted alloprimed CXCR3CXCR5CD8 T cells) suppressed Alloantibody production and enhanced graft survival when transferred into transplant recipients. Unlike CD8 T cells from wild-type or CXCR3 KO mice, CD8 T cells from CXCR5 KO mice do not develop Alloantibody-suppressor function. Similarly, only flow-sorted CXCR5CXCR3 (and not CXCR3CXCR5) OVA-primed OT-I CD8 T cells mediated in vivo suppression of anti-OVA antibody production. CONCLUSIONS These data support the conclusion that expression of CXCR5 by antigen-primed CD8 T cells is critical for the function of antibody-suppressor CD8 T cells.
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critical role of nkt cells in posttransplant Alloantibody production
PMC, 2014Co-Authors: Jason M Zimmerer, Steven M Elzein, Mahmoud Abdelrasoul, P Swamy, P B Sanghavi, C L Wright, Randy R Brutkiewicz, Ginny L. BumgardnerAbstract:We previously reported that posttransplant Alloantibody production in CD8-deficient hosts is IL-4+CD4+ T cell–dependent and IgG1 isotype-dominant. The current studies investigated the hypothesis that IL-4-producing natural killer T cells (NKT cells) contribute to maximal Alloantibody production. To investigate this, Alloantibody levels were examined in CD8-deficient WT, CD1d KO and Jα18 KO transplant recipients. We found that the magnitude of IgG1 Alloantibody production was critically dependent on the presence of type I NKT cells, which are activated by day 1 posttransplant. Unexpectedly, type I NKT cell contribution to enhanced IgG1 Alloantibody levels was interferon-γ-dependent and IL-4-independent. Cognate interactions between type I NKT and B cells alone do not stimulate Alloantibody production. Instead, NKT cells appear to enhance maturation of IL-4+CD4+ T cells. To our knowledge, this is the first report to substantiate a critical role for type I NKT cells in enhancing in vivo antibody production in response to endogenous antigenic stimuli.
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alloprimed cd8 t cells regulate Alloantibody and eliminate alloprimed b cells through perforin and fasl dependent mechanisms
American Journal of Transplantation, 2014Co-Authors: Jason M Zimmerer, Steven M Elzein, P B Sanghavi, C L Wright, T A Pham, K J Tobin, V M Sanders, Ginny L. BumgardnerAbstract:While it is well known that CD4+ T cells and B cells collaborate for antibody production, our group previously reported that CD8+ T cells down-regulate Alloantibody responses following transplantation. However, the exact mechanism involved in CD8+ T cell–mediated down-regulation of Alloantibody remains unclear. We also reported that Alloantibody production is enhanced when either perforin or FasL is deficient in transplant recipients. Here, we report that CD8+ T cell–deficient transplant recipient mice (high Alloantibody producers) exhibit an increased number of primed B cells compared to WT transplant recipients. Furthermore, CD8+ T cells require FasL, perforin and allospecificity to down-regulate posttransplant Alloantibody production. In vivo CD8-mediated clearance of alloprimed B cells was also FasL- and perforin-dependent. In vitro data demonstrated that recipient CD8+ T cells directly induce apoptosis of alloprimed IgG1+ B cells in co-culture in an allospecific and MHC class I-dependent fashion. Altogether these data are consistent with the interpretation that CD8+ T cells down-regulate posttransplant Alloantibody production by FasL- and perforin-dependent direct elimination of alloprimed IgG1+ B cells.
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cd8 t cells negatively regulate il 4 dependent igg1 dominant posttransplant Alloantibody production
Journal of Immunology, 2010Co-Authors: Jason M Zimmerer, Thomas A Pham, Virginia M Sanders, Ginny L. BumgardnerAbstract:We have previously reported that CD8(+) T cells significantly influence Ab production based on the observation that posttransplant Alloantibody levels in CD8-deficient murine hepatocyte transplant recipients are markedly enhanced. However, the precise mechanisms contributing to enhanced Alloantibody production in the absence of CD8(+) T cells is not understood. We hypothesized that alloactivated CD8(+) T cells inhibit Ab production by skewing toward a proinflammatory cytokine profile, whereas when these cells are absent, an anti-inflammatory cytokine profile shifts the alloimmune response toward Alloantibody production. To investigate this possibility, Alloantibody isotype profiles were examined in CD8-deficient and wild-type hepatocyte recipients. We found that IgG1 (IL-4-dependent isotype) was the dominant Alloantibody isotype in wild-type recipients as well as in CD8-deficient recipients, although the amount of Alloantibody in the latter group was substantially higher. Utilizing real-time PCR we found that CD4(+) T cells from wild-type recipients significantly upregulated IFN-γ but not IL-4 mRNA. In contrast, in the absence of CD8(+) T cells, CD4(+) T cells switched to significantly upregulate IL-4 mRNA, while IFN-γ was downregulated. IL-4 knockout mice do not produce any posttransplant Alloantibody. However, adoptive transfer of wild-type CD4(+) T cells into CD8-depleted IL-4 knockout mice restores high Alloantibody levels observed in CD8-depleted wild-type recipients. This suggests that IL-4-producing CD4(+) T cells are critical for posttransplant Alloantibody production. Additionally, this CD8-mediated regulation of posttransplant Alloantibody production is IFN-γ-dependent. Further elucidation of the mechanisms by which CD8(+) T cells influence Ab production will significantly contribute to development of therapies to manipulate humoral responses to Ag.
Dermot Mallon - One of the best experts on this subject based on the ideXlab platform.
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predicting humoral alloimmunity from differences in donor and recipient hla surface electrostatic potential
Journal of Immunology, 2018Co-Authors: Craig J Taylor, Andrew J Bradley, Dermot Mallon, Christiane Kling, Matthew Robb, Eva Ellinghaus, Dieter Kabelitz, Vasilis KosmoliaptsisAbstract:In transplantation, development of humoral alloimmunity against donor HLA is a major cause of organ transplant failure, but our ability to assess the immunological risk associated with a potential donor–recipient HLA combination is limited. We hypothesized that the capacity of donor HLA to induce a specific Alloantibody response depends on their structural and physicochemical dissimilarity compared with recipient HLA. To test this hypothesis, we first developed a novel computational scoring system that enables quantitative assessment of surface electrostatic potential differences between donor and recipient HLA molecules at the tertiary structure level [three-dimensional electrostatic mismatch score (EMS-3D)]. We then examined humoral alloimmune responses in healthy females subjected to a standardized injection of donor lymphocytes from their male partner. This analysis showed a strong association between the EMS-3D of donor HLA and donor-specific Alloantibody development; this relationship was strongest for HLA-DQ alloantigens. In the clinical transplantation setting, the immunogenic potential of HLA-DRB1 and -DQ mismatches expressed on donor kidneys, as assessed by their EMS-3D, was an independent predictor of development of donor-specific Alloantibody after graft failure. Collectively, these findings demonstrate the translational potential of our approach to improve immunological risk assessment and to decrease the burden of humoral alloimmunity in organ transplantation.
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predicting humoral alloimmunity from differences in donor recipient hla surface electrostatic potential
bioRxiv, 2018Co-Authors: Dermot Mallon, Craig J Taylor, Andrew J Bradley, Christiane Kling, Matthew Robb, Eva Ellinghaus, Dieter Kabelitz, Vasilis KosmoliaptsisAbstract:In transplantation, development of humoral alloimmunity against donor HLA is a major cause of organ transplant failure but our ability to assess the immunological risk associated with a potential donor-recipient HLA combination is limited. We hypothesised that the capacity of donor HLA to induce a specific Alloantibody response depends on their structural and physicochemical dissimilarity compared to recipient HLA. To test this hypothesis, we first developed a novel computational scoring system that enables quantitative assessment of surface electrostatic potential differences between donor and recipient HLA molecules at the tertiary structure level (electrostatic mismatch score-three dimensional; EMS-3D). We then examined humoral alloimmune responses in healthy females subjected to a standardised injection of donor lymphocytes from their male partner. This analysis showed a strong association between the EMS-3D of donor HLA and donor-specific Alloantibody development; this relationship was strongest for HLA-DQ alloantigens. In the clinical transplantation setting, the immunogenic potential of HLA-DRB1 and -DQ mismatches expressed on donor kidneys, as assessed by their EMS-3D, was an independent predictor of development of donor-specific Alloantibody after graft failure. Collectively, these findings demonstrate the translational potential of our approach to improve immunological risk assessment and to decrease the burden of humoral alloimmunity in organ transplantation.
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three dimensional structural modelling and calculation of electrostatic potentials of hla bw4 and bw6 epitopes to explain the molecular basis for Alloantibody binding toward predicting hla antigenicity and immunogenicity
Transplantation, 2015Co-Authors: Dermot Mallon, Andrew J Bradley, Craig J Taylor, Peter J Winn, Vasilis KosmoliaptsisAbstract:BackgroundWe have previously shown that qualitative assessment of surface electrostatic potential of HLA class I molecules helps explain serological patterns of Alloantibody binding. We have now used a novel computational approach to quantitate differences in surface electrostatic potential of HLA B
Craig J Taylor - One of the best experts on this subject based on the ideXlab platform.
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predicting humoral alloimmunity from differences in donor and recipient hla surface electrostatic potential
Journal of Immunology, 2018Co-Authors: Craig J Taylor, Andrew J Bradley, Dermot Mallon, Christiane Kling, Matthew Robb, Eva Ellinghaus, Dieter Kabelitz, Vasilis KosmoliaptsisAbstract:In transplantation, development of humoral alloimmunity against donor HLA is a major cause of organ transplant failure, but our ability to assess the immunological risk associated with a potential donor–recipient HLA combination is limited. We hypothesized that the capacity of donor HLA to induce a specific Alloantibody response depends on their structural and physicochemical dissimilarity compared with recipient HLA. To test this hypothesis, we first developed a novel computational scoring system that enables quantitative assessment of surface electrostatic potential differences between donor and recipient HLA molecules at the tertiary structure level [three-dimensional electrostatic mismatch score (EMS-3D)]. We then examined humoral alloimmune responses in healthy females subjected to a standardized injection of donor lymphocytes from their male partner. This analysis showed a strong association between the EMS-3D of donor HLA and donor-specific Alloantibody development; this relationship was strongest for HLA-DQ alloantigens. In the clinical transplantation setting, the immunogenic potential of HLA-DRB1 and -DQ mismatches expressed on donor kidneys, as assessed by their EMS-3D, was an independent predictor of development of donor-specific Alloantibody after graft failure. Collectively, these findings demonstrate the translational potential of our approach to improve immunological risk assessment and to decrease the burden of humoral alloimmunity in organ transplantation.
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predicting humoral alloimmunity from differences in donor recipient hla surface electrostatic potential
bioRxiv, 2018Co-Authors: Dermot Mallon, Craig J Taylor, Andrew J Bradley, Christiane Kling, Matthew Robb, Eva Ellinghaus, Dieter Kabelitz, Vasilis KosmoliaptsisAbstract:In transplantation, development of humoral alloimmunity against donor HLA is a major cause of organ transplant failure but our ability to assess the immunological risk associated with a potential donor-recipient HLA combination is limited. We hypothesised that the capacity of donor HLA to induce a specific Alloantibody response depends on their structural and physicochemical dissimilarity compared to recipient HLA. To test this hypothesis, we first developed a novel computational scoring system that enables quantitative assessment of surface electrostatic potential differences between donor and recipient HLA molecules at the tertiary structure level (electrostatic mismatch score-three dimensional; EMS-3D). We then examined humoral alloimmune responses in healthy females subjected to a standardised injection of donor lymphocytes from their male partner. This analysis showed a strong association between the EMS-3D of donor HLA and donor-specific Alloantibody development; this relationship was strongest for HLA-DQ alloantigens. In the clinical transplantation setting, the immunogenic potential of HLA-DRB1 and -DQ mismatches expressed on donor kidneys, as assessed by their EMS-3D, was an independent predictor of development of donor-specific Alloantibody after graft failure. Collectively, these findings demonstrate the translational potential of our approach to improve immunological risk assessment and to decrease the burden of humoral alloimmunity in organ transplantation.
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three dimensional structural modelling and calculation of electrostatic potentials of hla bw4 and bw6 epitopes to explain the molecular basis for Alloantibody binding toward predicting hla antigenicity and immunogenicity
Transplantation, 2015Co-Authors: Dermot Mallon, Andrew J Bradley, Craig J Taylor, Peter J Winn, Vasilis KosmoliaptsisAbstract:BackgroundWe have previously shown that qualitative assessment of surface electrostatic potential of HLA class I molecules helps explain serological patterns of Alloantibody binding. We have now used a novel computational approach to quantitate differences in surface electrostatic potential of HLA B
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predicting hla class ii alloantigen immunogenicity from the number and physiochemical properties of amino acid polymorphisms
Transplantation, 2009Co-Authors: Vasilis Kosmoliaptsis, Afzal N Chaudhry, David J. Halsall, Timothy R. Dafforn, Andrew J Bradley, Linda D Sharples, Craig J TaylorAbstract:Background. We have shown previously that human leukocyte antigen (HLA) class I immunogenicity can be predicted by the number, position, and physiochemical differences of polymorphic amino acids (AAs). We have now modeled the structural and physiochemical polymorphisms of HLA class II alloantigens and correlated these with humoral alloimmunity in sensitized patients awaiting kidney transplantation. Methods. Sera obtained from 30 patients with high levels of IgG HLA-specific antibodies were screened using single-antigen HLA antibody detection beads. A computer program was developed to determine the number of AA mismatches (after interlocus and intralocus subtraction) and their hydrophobicity and electrostatic mismatch score for each mismatched HLA-DR and -DQ specificity. Regression methods were used to compare these variables with the occurrence and magnitude of Alloantibody responses. Results. HLA-specific antibody was detected against 879 (55%) of 1604 mismatched HLA specificities evaluated. There was a strong correlation between increasing number of AA mismatches and the occurrence (P<0.001, odds ratio 3.85 per AA) and magnitude of Alloantibody responses (P<0.001); only 6% of alloantigens with 0 to 2 mismatched AA-induced Alloantibody (median fluorescence intensity 37) compared with 82% of alloantigens with more than or equal to 20 mismatched AAs (median fluorescence intensity 9969). Hydrophobicity and electrostatic mismatch scores also correlated closely with Alloantibody response (P<0.001), but neither variable had independent predictive value over the number of AA mismatches alone. Conclusion. Differences in the number of polymorphic AA mismatches and their physiochemical properties for a given recipient HLA type are strong predictors of class II alloantigen immunogenicity and Alloantibody response before kidney transplantation.