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Des Soye BJ, Melani RD, Hollas MAR, Duan J, Patrie SM, Fisher TD, Mattamana BB, Daud A, Pinelli DF, Ladner DP, Kelleher NL, Forte E. Characterization of the Antibody Response to SARS-CoV-2 Infection in COVID-19 Transplant versus Nontransplant Recipients by Ig-MS. J Proteome Res 2024; 23:3944-3957. [PMID: 39146476 DOI: 10.1021/acs.jproteome.4c00285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
Solid organ transplant recipients with immunosuppressant regimens to prevent rejection are less able to mount effective immune responses to pathogenic infection. Here, we apply a recently reported mass spectrometry-based serological approach known as Ig-MS to characterize immune responses against infection with SARS-CoV-2 in cohorts of transplant recipients and immunocompetent controls, both at a single early time point following COVID-19 diagnosis as well as over the course of one-month postdiagnosis. We found that the antibody repertoires generated by transplant recipients against SARS-CoV-2 do not differ significantly compared to immunocompetent individuals with regard to repertoire titer, clonality, or glycan composition. Importantly, our study is the first to characterize the evolution of antibody glycan profiles in transplant recipients with COVID-19 disease, presenting evidence that the evolution of glycan composition in these immunocompromised individuals is similar to that in immunocompetent people.
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Tambur AR, Bestard O, Campbell P, Chong AS, Barrio MC, Ford ML, Gebel HM, Heidt S, Hickey M, Jackson A, Kosmoliaptsis V, Lefaucheur C, Louis K, Mannon RB, Mengel M, Morris A, Pinelli DF, Reed EF, Schinstock C, Taupin JL, Valenzuela N, Wiebe C, Nickerson P. Sensitization in transplantation: Assessment of Risk 2022 Working Group Meeting Report. Am J Transplant 2023; 23:133-149. [PMID: 36695615 DOI: 10.1016/j.ajt.2022.11.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/20/2022] [Accepted: 11/02/2022] [Indexed: 01/13/2023]
Abstract
The Sensitization in Transplantation: Assessment of Risk workgroup is a collaborative effort of the American Society of Transplantation and the American Society of Histocompatibility and Immunogenetics that aims at providing recommendations for clinical testing, highlights gaps in current knowledge, and proposes areas for further research to enhance histocompatibility testing in support of solid organ transplantation. This report provides updates on topics discussed by the previous Sensitization in Transplantation: Assessment of Risk working groups and introduces 2 areas of exploration: non-human leukocyte antigen antibodies and utilization of human leukocyte antigen antibody testing measurement to evaluate the efficacy of antibody-removal therapies.
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Garcia-Sanchez C, Casillas-Abundis MA, Pinelli DF, Tambur AR, Hod-Dvorai R. Impact of SIRPα polymorphism on transplant outcomes in HLA-identical living donor kidney transplantation. Clin Transplant 2021; 35:e14406. [PMID: 34180101 DOI: 10.1111/ctr.14406] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 06/09/2021] [Accepted: 06/21/2021] [Indexed: 12/12/2022]
Abstract
Signal-regulatory protein α (SIRPα), a polymorphic inhibitory membrane-bound receptor, and its ligand CD47 have recently been implicated in the modulation of innate immune allorecognition in murine models. Here, we investigate the potential impact of SIRPα donor-recipient mismatches on graft outcomes in human kidney transplantation. To eliminate the specific role of HLA-matching in alloresponse, we genotyped the two most common variants of SIRPα in a cohort of 55 HLA-identical, biologically-related, donor-recipient pairs. 69% of pairs were SIRPα identical. No significant differences were found between donor-recipient SIRPα-mismatch status and T cell-mediated rejection/borderline changes (25.8% vs. 25%) or slow graft function (15.8% vs. 17.6%). A trend towards more graft failure (GF) (23.5% vs. 5.3%, P = .06), interstitial inflammation (50% vs. 23%, P = .06) and significant changes in peritubular capillaritis (ptc) (25% vs. 0%, P = .02) were observed in the SIRPα-mismatched group. Unexpectedly, graft-versus-host (GVH) SIRPα-mismatched pairs exhibited higher rates of GF and tubulitis (38% vs. 5%, P = .031 and .61 ± .88 vs. 0, P = .019; respectively). Whether the higher prevalence of ptc in SIRPα-mismatched recipients and the higher rates of GF in GVH SIRPα-mismatched pairs represent a potential role for SIRPα in linking innate immunity and alloimmune rejection requires further investigation in larger cohorts.
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Jackson AM, Pinelli DF. Understanding the impact of HLA molecular mismatch in solid organ transplantation: Are we there yet? Am J Transplant 2021; 21:9-10. [PMID: 33107168 DOI: 10.1111/ajt.16376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 09/30/2020] [Accepted: 10/13/2020] [Indexed: 01/25/2023]
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Morris AB, Pinelli DF, Liu D, Wagener M, Ford ML. Memory T cell-mediated rejection is mitigated by FcγRIIB expression on CD8 + T cells. Am J Transplant 2020; 20:2206-2215. [PMID: 32154641 PMCID: PMC7395896 DOI: 10.1111/ajt.15837] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 01/19/2020] [Accepted: 02/08/2020] [Indexed: 01/25/2023]
Abstract
Donor-reactive memory T cells generated via heterologous immunity represent a potent barrier to long-term graft survival following transplantation because of their increased precursor frequency, rapid effector function, altered trafficking patterns, and reduced reliance on costimulation signals for activation. Thus, the identification of pathways that control memory T cell survival and secondary recall potential may provide new opportunities for therapeutic intervention. Here, we discovered that donor-specific effector/memory CD8+ T cell populations generated via exposure to acute vs latent vs chronic infections contain differential frequencies of CD8+ T cells expressing the inhibitory Fc receptor FcγRIIB. Results indicated that frequencies of FcγRIIB-expressing CD8+ donor-reactive memory T cells inversely correlated with allograft rejection. Furthermore, adoptive T cell transfer of Fcgr2b-/- CD8+ T cells resulted in an accumulation of donor-specific CD8+ memory T cells and enhanced recall responses, indicating that FcγRIIB functions intrinsically to limit T cell CD8+ survival in vivo. Lastly, we show that deletion of FcγRIIB on donor-specific CD8+ memory T cells precipitated costimulation blockade-resistant rejection. These data therefore identify a novel cell-intrinsic inhibitory pathway that functions to limit the risk of memory T cell-mediated rejection following transplantation and suggest that therapeutic manipulation of this pathway could improve outcomes in sensitized patients.
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Pinelli DF, Tambur AR. Virtual crossmatching for deceased donor transplantation: one size does not fit all. Kidney Int 2020; 97:659-662. [DOI: 10.1016/j.kint.2020.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 01/08/2020] [Accepted: 02/06/2020] [Indexed: 10/24/2022]
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Morris AB, Farley CR, Pinelli DF, Adams LE, Cragg MS, Boss JM, Scharer CD, Fribourg M, Cravedi P, Heeger PS, Ford ML. Signaling through the Inhibitory Fc Receptor FcγRIIB Induces CD8 + T Cell Apoptosis to Limit T Cell Immunity. Immunity 2020; 52:136-150.e6. [PMID: 31940267 PMCID: PMC7326381 DOI: 10.1016/j.immuni.2019.12.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 09/20/2019] [Accepted: 12/12/2019] [Indexed: 12/11/2022]
Abstract
Effector CD8+ T cells are important mediators of adaptive immunity, and receptor-ligand interactions that regulate their survival may have therapeutic potential. Here, we identified a subset of effector CD8+ T cells that expressed the inhibitory fragment crystallizable (Fc) receptor FcγRIIB following activation and multiple rounds of division. CD8+ T cell-intrinsic genetic deletion of Fcgr2b increased CD8+ effector T cell accumulation, resulting in accelerated graft rejection and decreased tumor volume in mouse models. Immunoglobulin G (IgG) antibody was not required for FcγRIIB-mediated control of CD8+ T cell immunity, and instead, the immunosuppressive cytokine fibrinogen-like 2 (Fgl2) was a functional ligand for FcγRIIB on CD8+ T cells. Fgl2 induced caspase-3/7-mediated apoptosis in Fcgr2b+, but not Fcgr2b-/-, CD8+ T cells. Increased expression of FcγRIIB correlated with freedom from rejection following withdrawal from immunosuppression in a clinical trial of kidney transplant recipients. Together, these findings demonstrate a cell-intrinsic coinhibitory function of FcγRIIB in regulating CD8+ T cell immunity.
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Tambur AR, McDowell H, Hod-Dvorai R, Abundis MAC, Pinelli DF. The quest to decipher HLA immunogenicity: Telling friend from foe. Am J Transplant 2019; 19:2910-2925. [PMID: 31165546 DOI: 10.1111/ajt.15489] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 05/14/2019] [Accepted: 05/15/2019] [Indexed: 01/25/2023]
Abstract
Molecular mismatch load analysis was recently introduced as a means for performing risk stratification following organ transplantation. However, although good correlation was demonstrated between molecular mismatch load and generation of de novo donor-specific HLA antibody (DSA), quite a few exceptions exist, and the underlying factors that define HLA immunogenicity remain unclear. Herein, we present a new paradigm to interrogate differences between molecular mismatches that lead to the generation of de novo DSA and those that do not (the 2MM1DSA cohort). Specifically, patients transplanted across 2 HLA-DQ mismatches, who formed de novo DSA only to one mismatch (foe) but not the other (friend), provide a unique environment in which patient-specific factors that affect the immune response other than immunogenicity, such as infection and immunosuppression, can be controlled for. It further permits focusing on mismatches uniquely exhibited by the de novo DSA allele, rather than mismatches shared by both DSA and non-DSA alleles. This concept paper illustrates several examples, highlights the need for center-specific or population-specific cutoff values for posttransplant risk stratification, and mostly argues that if there is no direct correlation between molecular mismatch load and immunogenicity, then molecular mismatch load must not be adopted as an approach for equitable organ allocation.
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Pinelli DF, Zachary AA, Friedewald JJ, Gjertson DW, Evans MA, Chatroop EN, Leffell MS, Vo AA, Jordan SC, Montgomery RA, Tambur AR. Prognostic tools to assess candidacy for and efficacy of antibody-removal therapy. Am J Transplant 2019; 19:381-390. [PMID: 29981209 DOI: 10.1111/ajt.15007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 06/20/2018] [Accepted: 07/01/2018] [Indexed: 01/25/2023]
Abstract
Currently, the ability to predict or monitor the efficacy of HLA antibody-removal therapies is deficient. We previously reported that titration studies are a consistent and accurate means of assessing antibody strength. To test whether titration studies can also predict which patients are better candidates for desensitization, we studied 38 patients from 3 centers (29 receiving plasmapheresis/low-dose intravenous immunoglobulin [IVIg]; 9 patients receiving high-dose IVIg). For patients undergoing plasmapheresis/low-dose IVIg, antibody titer reduction correlated with number of treatment cycles for both class I and II antibodies but only up to approximately 4 cycles. Reduction in titer slowed with additional cycles, suggesting a limit to the efficacy of this approach. Furthermore, initial titer (predesensitization) can guide the selection of candidates for successful antibody-removal treatment. In our experience, patients with antibodies at an initial titer >1:512 could not be reduced to the goal of a negative lymphocyte crossmatch, corresponding to a 1:16 titer, despite a significant increase in the number of treatment cycles. Change in mean fluorescence intensity (MFI) value did not correlate with success of treatment if initial MFI values were >10 000, likely due to single antigen bead saturation. Overall, we present a potential prognostic tool to predict candidacy and a monitoring tool to assess efficacy of desensitization treatment.
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Pinelli DF, Patel N, Tambur AR. P085 Improving hla laboratory workflow management and “Going paperless”. Hum Immunol 2018. [DOI: 10.1016/j.humimm.2018.07.144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Pinelli DF, Friedewald JJ, Haarberg KMK, Radhakrishnan SL, Zitzner JR, Hanshew WE, Tambur AR. Assessing the potential of angiotensin II type 1 receptor and donor specific anti-endothelial cell antibodies to predict long-term kidney graft outcome. Hum Immunol 2017; 78:421-427. [PMID: 28372986 DOI: 10.1016/j.humimm.2017.03.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 03/27/2017] [Accepted: 03/28/2017] [Indexed: 12/14/2022]
Abstract
Endothelial cell antigens have been reported as potential targets for antibodies in the context of organ transplantation, leading to increased risk for graft failure. Serum samples from 142 consecutive living donor kidney recipients were tested for the presence of antibodies to angiotensin II - type 1 receptor (AT1R), donor endothelial cells, and donor HLA. Graft survival was monitored for five years post-transplant, and secondary outcomes, including biopsy-proven rejection, proteinuria, biopsy-proven vasculopathy, and renal function based on serum creatinine were also assessed for the first two to three years. AT1R antibody levels were positive (>17U/mL) in 11.3%, 18.8% and 8.1% of patients pre-transplant, post-transplant and at time of indication biopsy, respectively. XM-ONE assay was positive in 17.6% of patients pre-transplant (7 IgG+; 15 IgM+; 3 IgG+/IgM+). Overall, 4 patients experienced antibody-mediated rejection (AMR), 31 borderline cellular rejection (BCR), 19 cellular rejection (CR) and 3 mixed AMR and CR within the first 24months. While pre-existing and de novo donor-specific HLA antibodies were associated with graft failure and many secondary outcomes, no statistical association was found for either anti-endothelial or anti-AT1R antibodies, indicating that these tests may not be the best predictors of graft outcome in living donor renal transplantation.
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Shorter SK, Schnell FJ, McMaster SR, Pinelli DF, Andargachew R, Evavold BD. Viral Escape Mutant Epitope Maintains TCR Affinity for Antigen yet Curtails CD8 T Cell Responses. PLoS One 2016; 11:e0149582. [PMID: 26915099 PMCID: PMC4767940 DOI: 10.1371/journal.pone.0149582] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 02/01/2016] [Indexed: 12/03/2022] Open
Abstract
T cells have the remarkable ability to recognize antigen with great specificity and in turn mount an appropriate and robust immune response. Critical to this process is the initial T cell antigen recognition and subsequent signal transduction events. This antigen recognition can be modulated at the site of TCR interaction with peptide:major histocompatibility (pMHC) or peptide interaction with the MHC molecule. Both events could have a range of effects on T cell fate. Though responses to antigens that bind sub-optimally to TCR, known as altered peptide ligands (APL), have been studied extensively, the impact of disrupting antigen binding to MHC has been highlighted to a lesser extent and is usually considered to result in complete loss of epitope recognition. Here we present a model of viral evasion from CD8 T cell immuno-surveillance by a lymphocytic choriomeningitis virus (LCMV) escape mutant with an epitope for which TCR affinity for pMHC remains high but where the antigenic peptide binds sub optimally to MHC. Despite high TCR affinity for variant epitope, levels of interferon regulatory factor-4 (IRF4) are not sustained in response to the variant indicating differences in perceived TCR signal strength. The CD8+ T cell response to the variant epitope is characterized by early proliferation and up-regulation of activation markers. Interestingly, this response is not maintained and is characterized by a lack in IL-2 and IFNγ production, increased apoptosis and an abrogated glycolytic response. We show that disrupting the stability of peptide in MHC can effectively disrupt TCR signal strength despite unchanged affinity for TCR and can significantly impact the CD8+ T cell response to a viral escape mutant.
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Dvorai RH, Pinelli DF, Tambur AR. HLA Epitopes - Are We Ready for Clinical Prime Time? Historic Perspective and Future Needs. CLINICAL TRANSPLANTS 2016; 32:63-71. [PMID: 28564523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A significant barrier to long-term transplant success is the development of de novo donor-specific human leukocyte antigen (HLA) antibodies. The best approach to minimize the risk of developing such antibodies is an HLA identical transplant, but the likelihood of finding such an organ is very low. The alternative is to identify "permissible mismatches" - HLA antigen mismatches that are less likely to induce an immune response. In the past few years, it has become clear that matching at the "epitope level" is the likely solution; however, we are still struggling with how to define HLA epitopes. Herein, we provide a short review of the development of the epitope concept within the HLA field, with the hope that it sheds light on present knowledge. We follow with our personal opinion on where the future is leading us.
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Pinelli DF, Wakeman BS, Wagener ME, Speck SH, Ford ML. Rapamycin ameliorates the CTLA4-Ig-mediated defect in CD8(+) T cell immunity during gammaherpesvirus infection. Am J Transplant 2015; 15:2576-87. [PMID: 25989700 PMCID: PMC5389899 DOI: 10.1111/ajt.13326] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 03/20/2015] [Accepted: 03/25/2015] [Indexed: 01/25/2023]
Abstract
Latent viral infections are a major concern among immunosuppressed transplant patients. During clinical trials with belatacept, a CTLA4-Ig fusion protein, patients showed an increased risk of Epstein-Barr virus-associated posttransplant lymphoproliferative disorder, thought to be due to a deficient primary CD8(+) T cell response to the virus. Using a murine model of latent viral infection, we observed that rapamycin treatment alone led to a significant increase in virus-specific CD8(+) T cells, as well as increased functionality of these cells, including the ability to make multiple cytokines, while CTLA4-Ig treatment alone significantly dampened the response and inhibited the generation of polyfunctional antigen-specific CD8(+) T cells. However, the addition of rapamycin to the CTLA4-Ig regimen was able to quantitatively and qualitatively restore the antigen-specific CD8(+) T cell response to the virus. This improvement was physiologically relevant, in that CTLA4-Ig treated animals exhibited a greater viral burden following infection that was reduced to levels observed in untreated immunocompetent animals by the addition of rapamycin. These results reveal that modulation of T cell differentiation though inhibition of mTOR signaling can restore virus-specific immune competence even in the absence of CD28 costimulation, and have implications for improving protective immunity in transplant recipients.
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Pinelli DF, Ford ML. Novel insights into anti-CD40/CD154 immunotherapy in transplant tolerance. Immunotherapy 2015; 7:399-410. [PMID: 25917630 PMCID: PMC5441999 DOI: 10.2217/imt.15.1] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Since the discovery of the CD40-CD154 costimulatory pathway and its critical role in the adaptive immune response, there has been considerable interest in therapeutically targeting this interaction with monoclonal antibodies in transplantation. Unfortunately, initial promise in animal models gave way to disappointment in clinical trials following a number of thromboembolic complications. However, recent mechanistic studies have identified the mechanism of these adverse events, as well as detailed a myriad of interactions between CD40 and CD154 on a wide variety of immune cell types and the critical role of this pathway in generating both humoral and cell-mediated alloreactive responses. This has led to resurgence in interest and the potential resurrection of anti-CD154 and anti-CD40 antibodies as clinically viable therapeutic options.
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Pinelli DF, Wagener ME, Liu D, Yamniuk A, Tamura J, Grant S, Larsen CP, Suri A, Nadler SG, Ford ML. An anti-CD154 domain antibody prolongs graft survival and induces Foxp3(+) iTreg in the absence and presence of CTLA-4 Ig. Am J Transplant 2013; 13:3021-30. [PMID: 24007441 PMCID: PMC4287239 DOI: 10.1111/ajt.12417] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 06/14/2013] [Accepted: 07/01/2013] [Indexed: 01/25/2023]
Abstract
The use of monoclonal antibodies targeting the CD154 molecule remains one of the most effective means of promoting graft tolerance in animal models, but thromboembolic complications during early clinical trials have precluded their use in humans. Furthermore, the role of Fc-mediated deletion of CD154-expressing cells in the observed efficacy of these reagents remains controversial. Therefore, determining the requirements for anti-CD154-induced tolerance will instruct the development of safer but equally efficacious treatments. To investigate the mechanisms of action of anti-CD154 therapy, two alternative means of targeting the CD40-CD154 pathway were used: a nonagonistic anti-CD40 antibody and an Fc-silent anti-CD154 domain antibody. We compared these therapies to an Fc-intact anti-CD154 antibody in both a fully allogeneic model and a surrogate minor antigen model in which the fate of alloreactive cells could be tracked. Results indicated that anti-CD40 mAbs as well as Fc-silent anti-CD154 domain antibodies were equivalent to Fc-intact anti-CD154 mAbs in their ability to inhibit alloreactive T cell expansion, attenuate cytokine production of antigen-specific T cells and promote the conversion of Foxp3(+) iTreg. Importantly, iTreg conversion observed with Fc-silent anti-CD154 domain antibodies was preserved in the presence of CTLA4-Ig, suggesting that this therapy is a promising candidate for translation to clinical use.
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Ferrer IR, Liu D, Pinelli DF, Koehn BH, Stempora LL, Ford ML. CD40/CD154 blockade inhibits dendritic cell expression of inflammatory cytokines but not costimulatory molecules. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2012; 189:4387-95. [PMID: 23002440 PMCID: PMC3478479 DOI: 10.4049/jimmunol.1201757] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Blockade of the CD40/CD154 pathway remains one of the most effective means of promoting graft survival following transplantation. However, the effects of CD40/CD154 antagonism on dendritic cell (DC) phenotype and functionality following transplantation remain incompletely understood. To dissect the effects of CD154/CD40 blockade on DC activation in vivo, we generated hematopoietic chimeras in mice that expressed a surrogate minor Ag (OVA). Adoptive transfer of OVA-specific CD4(+) and CD8(+) T cells led to chimerism rejection, which was inhibited by treatment with CD154 blockade. Surprisingly, CD154 antagonism did not alter the expression of MHC and costimulatory molecules on CD11c(+) DCs compared with untreated controls. However, DCs isolated from anti-CD154-treated animals exhibited a significant reduction in inflammatory cytokine secretion. Combined blockade of inflammatory cytokines IL-6 and IL-12p40 attenuated the expansion of Ag-specific CD4(+) and CD8(+) T cells and transiently inhibited the rejection of OVA-expressing cells. These results suggest that a major effect of CD154 antagonism in vivo is an impairment in the provision of signal three during donor-reactive T cell programming, as opposed to an impact on the provision of signal two. We conclude that therapies designed to target inflammatory cytokines during donor-reactive T cell activation may be beneficial in attenuating these responses and prolonging graft survival.
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