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Nicosia M, Valujskikh A. Recognizing Complexity of CD8 T Cells in Transplantation. Transplantation 2024:00007890-990000000-00734. [PMID: 38637929 DOI: 10.1097/tp.0000000000005001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
The major role of CD8+ T cells in clinical and experimental transplantation is well documented and acknowledged. Nevertheless, the precise impact of CD8+ T cells on graft tissue injury is not completely understood, thus impeding the development of specific treatment strategies. The goal of this overview is to consider the biology and functions of CD8+ T cells in the context of experimental and clinical allotransplantation, with special emphasis on how this cell subset is affected by currently available and emerging therapies.
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Affiliation(s)
- Michael Nicosia
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH
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2
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Sun J(A, Adil A, Biniazan F, Haykal S. Immunogenicity and tolerance induction in vascularized composite allotransplantation. FRONTIERS IN TRANSPLANTATION 2024; 3:1350546. [PMID: 38993748 PMCID: PMC11235364 DOI: 10.3389/frtra.2024.1350546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 01/29/2024] [Indexed: 07/13/2024]
Abstract
Vascularized composite allotransplantation (VCA) is the transplantation of multiple tissues such as skin, muscle, bone, nerve, and vessels, as a functional unit (i.e., hand or face) to patients suffering from major tissue trauma and functional deficits. Though the surgical feasibility has been optimized, issues regarding graft rejection remains. VCA rejection involves a diverse population of cells but is primarily driven by both donor and recipient lymphocytes, antigen-presenting cells, macrophages, and other immune as well as donor-derived cells. In addition, it is commonly understood that different tissues within VCA, such as the skin, elicits a stronger rejection response. Currently, VCA recipients are required to follow potent and lifelong immunosuppressing regimens to maximize graft survival. This puts patients at risk for malignancies, opportunistic infections, and cancers, thereby posing a need for less perilous methods of inducing graft tolerance. This review will provide an overview of cell populations and mechanisms, specific tissue involved in VCA rejection, as well as an updated scope of current methods of tolerance induction.
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Affiliation(s)
- Jiahui (Angela) Sun
- Latner Thoracic Surgery Laboratories, University Health Network, Toronto General Hospital, University of Toronto, Toronto, ON, Canada
- Institute of Medical Science, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Aisha Adil
- Latner Thoracic Surgery Laboratories, University Health Network, Toronto General Hospital, University of Toronto, Toronto, ON, Canada
- Institute of Medical Science, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Felor Biniazan
- Latner Thoracic Surgery Laboratories, University Health Network, Toronto General Hospital, University of Toronto, Toronto, ON, Canada
| | - Siba Haykal
- Latner Thoracic Surgery Laboratories, University Health Network, Toronto General Hospital, University of Toronto, Toronto, ON, Canada
- Institute of Medical Science, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Division of Plastic & Reconstructive Surgery, Department of Surgery, University of Toronto, Toronto, ON, Canada
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3
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MacNabb BW, Kline J. MHC cross-dressing in antigen presentation. Adv Immunol 2023; 159:115-147. [PMID: 37996206 DOI: 10.1016/bs.ai.2023.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
Dendritic cells (DCs) orchestrate T cell responses by presenting antigenic peptides on major histocompatibility complex (MHC) and providing costimulation and other instructive signals. Professional antigen presenting cells (APCs), including DCs, are uniquely capable of generating and presenting peptide antigens derived from exogenous proteins. In addition to these canonical cross-presentation and MHC-II presentation pathways, APCs can also display exogenous peptide/MHC (p/MHC) acquired from neighboring cells and extracellular vesicles (EVs). This process, known as MHC cross-dressing, has been implicated in the regulation of T cell responses in a variety of in vivo contexts, including allogeneic solid organ transplantation, tumors, and viral infection. Although the occurrence of MHC cross-dressing has been clearly demonstrated, the importance of this antigen presentation mechanism continues to be elucidated. The contribution of MHC cross-dressing to overall antigen presentation has been obfuscated by the fact that DCs express the same MHC alleles as all other cells in the host, making it difficult to distinguish p/MHC generated within the DC from p/MHC acquired from another cell. As a result, much of what is known about MHC cross-dressing comes from studies using allogeneic organ transplantation and bone marrow chimeric mice, though recent development of mice bearing conditional knockout MHC and β2-microglobulin alleles should facilitate substantial progress in the coming years. In this review, we highlight recent advances in our understanding of MHC cross-dressing and its role in activating T cell responses in various contexts, as well as the experimental insights into the mechanism by which it occurs.
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Affiliation(s)
- Brendan W MacNabb
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States.
| | - Justin Kline
- Department of Medicine, Committee on Immunology, and Committee on Cancer Biology, University of Chicago, Chicago, IL, United States.
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Al-Adra DP, Thangavelu G, Lin J, Chan WF, Ellestad KK, Boon L, Anderson CC. CD8 T Cells Target Antigen Cross-Presented by Bone Marrow Derived Cells to Induce Bystander Rejection of Grafts Lacking the Cognate Peptide-MHC. Cell Transplant 2022; 31:9636897221136149. [PMID: 36367048 PMCID: PMC9659770 DOI: 10.1177/09636897221136149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
CD8 T cells play a key role in cancer immunotherapy and allograft rejection. However, it is not clear how they kill cells and tissues that do not have the agonist peptide-major histocompatibility complex (MHC) on their surface, as in the settings of MHC class I deficient tumors and indirect rejection of MHC-mismatched transplants. CD8 T cells might respond to agonist antigen cross-presented on hematopoietic cells, leading to a "bystander" rejection. Alternatively, they may recognize agonist antigen cross-presented on recipient endothelial cells and kill the tissue's vital blood supply. The latter mechanism predicts that all non-vascularized grafts, grafts dependent on in-growth of recipient blood vessels, will be susceptible to CD8 T cell mediated indirect rejection. In contrast, we show here that non-vascularized transplants, bearing the same agonist antigen, are not universally susceptible to this rejection pathway. Non-vascularized skin, but not islet or heart tissue transplants were indirectly rejected by CD8 T cells. Furthermore, CD8 T cells were able to indirectly reject skin grafts when recipient MHC class I expression was restricted to bone marrow derived cells but not when it was restricted to radioresistant cells (e.g. endothelial cells). These findings argue against a major role for endothelial cell cross-presentation in killing of tissue that does not present the agonist peptide-MHC class I. Instead, the data suggests that cross-presentation by recipient hematopoietic cells underlies the CD8 T cell mediated killing of tissue that is unable to directly present the target peptide-MHC class I.
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Affiliation(s)
- David P. Al-Adra
- Department of Surgery, University of Alberta, Edmonton, AB, Canada,Alberta Diabetes and Transplant Institutes, University of Alberta, Edmonton, AB, Canada,Division of Transplantation, Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Govindarajan Thangavelu
- Department of Surgery, University of Alberta, Edmonton, AB, Canada,Alberta Diabetes and Transplant Institutes, University of Alberta, Edmonton, AB, Canada
| | - Jiaxin Lin
- Department of Surgery, University of Alberta, Edmonton, AB, Canada,Alberta Diabetes and Transplant Institutes, University of Alberta, Edmonton, AB, Canada
| | - William F.N. Chan
- Department of Surgery, University of Alberta, Edmonton, AB, Canada,Alberta Diabetes and Transplant Institutes, University of Alberta, Edmonton, AB, Canada
| | - Kristofor K. Ellestad
- Alberta Diabetes and Transplant Institutes, University of Alberta, Edmonton, AB, Canada,Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada,Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
| | | | - Colin C. Anderson
- Department of Surgery, University of Alberta, Edmonton, AB, Canada,Alberta Diabetes and Transplant Institutes, University of Alberta, Edmonton, AB, Canada,Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada,Colin C. Anderson, Department of Surgery, University of Alberta, Edmonton, AB T6G 2E1, Canada.
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5
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Karahan GE, Claas FHJ, Heidt S. Pre-existing Alloreactive T and B Cells and Their Possible Relevance for Pre-transplant Risk Estimation in Kidney Transplant Recipients. Front Med (Lausanne) 2020; 7:340. [PMID: 32793610 PMCID: PMC7385137 DOI: 10.3389/fmed.2020.00340] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 06/08/2020] [Indexed: 12/25/2022] Open
Abstract
In allogeneic transplantation, genetic disparities between patient and donor may lead to cellular and humoral immune responses mediated by both naïve and memory alloreactive cells of the adaptive immune system. This review will focus on alloreactive T and B cells with emphasis on the memory compartment, their role in relation to kidney rejection, and in vitro assays to detect these alloreactive cells. Finally, the potential additional value of utilizing donor-specific memory T and B cell assays supplementary to current routine pre-transplant risk assessment of kidney transplant recipients will be discussed.
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Affiliation(s)
- Gonca E Karahan
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, Netherlands
| | - Frans H J Claas
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, Netherlands
| | - Sebastiaan Heidt
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, Netherlands
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Lei H, Reinke P, Volk HD, Lv Y, Wu R. Mechanisms of Immune Tolerance in Liver Transplantation-Crosstalk Between Alloreactive T Cells and Liver Cells With Therapeutic Prospects. Front Immunol 2019; 10:2667. [PMID: 31803188 PMCID: PMC6877506 DOI: 10.3389/fimmu.2019.02667] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 10/28/2019] [Indexed: 12/11/2022] Open
Abstract
Liver transplantation (LTx) is currently the most powerful treatment for end-stage liver disease. Although liver allograft is more tolerogenic compared to other solid organs, the majority of LTx recipients still require long-term immune suppression (IS) to control the undesired alloimmune responses, which can lead to severe side effects. Thus, understanding the mechanism of liver transplant tolerance and crosstalk between immune cells, especially alloreactive T cells and liver cells, can shed light on more specific tolerance induction strategies for future clinical translation. In this review, we focus on alloreactive T cell mediated immune responses and their crosstalk with liver sinusoidal endothelial cells (LSECs), hepatocytes, hepatic stellate cells (HSCs), and cholangiocytes in transplant setting. Liver cells mainly serve as antigen presenting cells (APCs) to T cells, but with low expression of co-stimulatory molecules. Crosstalk between them largely depends on the different expression of adhesion molecules and chemokine receptors. Inflammatory cytokines secreted by immune cells further elaborate this crosstalk and regulate the fate of naïve T cells differentiation within the liver graft. On the other hand, regulatory T cells (Tregs) play an essential role in inducing and keeping immune tolerance in LTx. Tregs based adoptive cell therapy provides an excellent therapeutic option for clinical transplant tolerance induction. However, many questions regarding cell therapy still need to be solved. Here we also address the current clinical trials of adoptive Tregs therapy and other tolerance induction strategies in LTx, together with future challenges for clinical translation from bench to bedside.
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Affiliation(s)
- Hong Lei
- National Local Joint Engineering Research Center for Precision Surgery and Regenerative Medicine, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.,Berlin Institute of Health Center for Regenerative Therapies, Charité University Medicine Berlin, Berlin, Germany
| | - Petra Reinke
- Berlin Institute of Health Center for Regenerative Therapies, Charité University Medicine Berlin, Berlin, Germany.,Berlin Center of Advanced Therapies, Berlin, Germany
| | - Hans-Dieter Volk
- Berlin Institute of Health Center for Regenerative Therapies, Charité University Medicine Berlin, Berlin, Germany.,Institute of Medical Immunology, Charité University Medicine Berlin, Berlin, Germany
| | - Yi Lv
- National Local Joint Engineering Research Center for Precision Surgery and Regenerative Medicine, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Rongqian Wu
- National Local Joint Engineering Research Center for Precision Surgery and Regenerative Medicine, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
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Siu JHY, Surendrakumar V, Richards JA, Pettigrew GJ. T cell Allorecognition Pathways in Solid Organ Transplantation. Front Immunol 2018; 9:2548. [PMID: 30455697 PMCID: PMC6230624 DOI: 10.3389/fimmu.2018.02548] [Citation(s) in RCA: 134] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Accepted: 10/17/2018] [Indexed: 02/02/2023] Open
Abstract
Transplantation is unusual in that T cells can recognize alloantigen by at least two distinct pathways: as intact MHC alloantigen on the surface of donor cells via the direct pathway; and as self-restricted processed alloantigen via the indirect pathway. Direct pathway responses are viewed as strong but short-lived and hence responsible for acute rejection, whereas indirect pathway responses are typically thought to be much longer lasting and mediate the progression of chronic rejection. However, this is based on surprisingly scant experimental evidence, and the recent demonstration that MHC alloantigen can be re-presented intact on recipient dendritic cells-the semi-direct pathway-suggests that the conventional view may be an oversimplification. We review recent advances in our understanding of how the different T cell allorecognition pathways are triggered, consider how this generates effector alloantibody and cytotoxic CD8 T cell alloresponses and assess how these responses contribute to early and late allograft rejection. We further discuss how this knowledge may inform development of cellular and pharmacological therapies that aim to improve transplant outcomes, with focus on the use of induced regulatory T cells with indirect allospecificity and on the development of immunometabolic strategies. KEY POINTS Acute allograft rejection is likely mediated by indirect and direct pathway CD4 T cell alloresponses.Chronic allograft rejection is largely mediated by indirect pathway CD4 T cell responses. Direct pathway recognition of cross-dressed endothelial derived MHC class II alloantigen may also contribute to chronic rejection, but the extent of this contribution is unknown.Late indirect pathway CD4 T cell responses will be composed of heterogeneous populations of allopeptide specific T helper cell subsets that recognize different alloantigens and are at various stages of effector and memory differentiation.Knowledge of the precise indirect pathway CD4 T cell responses active at late time points in a particular individual will likely inform the development of alloantigen-specific cellular therapies and will guide immunometabolic modulation.
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Abstract
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.
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Sivaganesh S, Harper SJ, Conlon TM, Callaghan CJ, Saeb-Parsy K, Negus MC, Motallebzadeh R, Bolton EM, Bradley JA, Pettigrew GJ. Copresentation of intact and processed MHC alloantigen by recipient dendritic cells enables delivery of linked help to alloreactive CD8 T cells by indirect-pathway CD4 T cells. THE JOURNAL OF IMMUNOLOGY 2013; 190:5829-38. [PMID: 23630361 DOI: 10.4049/jimmunol.1300458] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In transplantation, direct-pathway CD8 T cells that recognize alloantigen on donor cells require CD4 help for activation and cytolytic function. The ability of indirect-pathway CD4 T cells to provide this help remains unexplained, because a fundamental requirement for epitope linkage is seemingly broken. The simultaneous presentation, by host dendritic cells (DCs), of both intact MHC class I alloantigen and processed alloantigen would deliver linked help, but has not been demonstrated definitively. In this study, we report that following in vitro coculture with BALB/c DCs, small numbers (~1.5%) of C57BL/6 (B6) DCs presented acquired H-2(d) alloantigen both as processed allopeptide and as unprocessed Ag. This represented class I alloantigen provides a conformational epitope for direct-pathway allorecognition, because B6 DCs isolated from cocultures and transferred to naive B6 mice provoked cytotoxic CD8 T cell alloimmunity. Crucially, this response was dependent upon simultaneous presentation of class II-restricted allopeptide, because despite acquiring similar amounts of H-2(d) alloantigen upon coculture, MHC class II-deficient B6 DCs failed to elicit cytotoxic alloimmunity. The relevance of this pathway to solid-organ transplantation was then confirmed by the demonstration that CD8 T cell cytotoxicity was provoked in secondary recipients by transfer of DCs purified from wild-type, but not from MHC class II-deficient, C57BL/6 recipients of BALB/c heart transplants. These experiments demonstrate that representation of conformationally intact MHC alloantigen by recipient APC can induce cytotoxic alloimmunity, but simultaneous copresentation of processed allopeptide is essential, presumably because this facilitates linked recognition by indirect-pathway CD4 Th cells.
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Affiliation(s)
- Siva Sivaganesh
- Department of Surgery, University of Cambridge, Cambridge CB2 0QQ, United Kingdom
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Ying H, Fu H, Rose ML, McCormack AM, Sarathchandra P, Okkenhaug K, Marelli-Berg FM. Genetic or pharmaceutical blockade of phosphoinositide 3-kinase p110δ prevents chronic rejection of heart allografts. PLoS One 2012; 7:e32892. [PMID: 22479345 PMCID: PMC3316549 DOI: 10.1371/journal.pone.0032892] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 02/07/2012] [Indexed: 11/18/2022] Open
Abstract
Chronic rejection is the major cause of long-term heart allograft failure, characterized by tissue infiltration by recipient T cells with indirect allospecificity. Phosphoinositol-3-kinase p110δ is a key mediator of T cell receptor signaling, regulating both T cell activation and migration of primed T cells to non-lymphoid antigen-rich tissue. We investigated the effect of genetic or pharmacologic inactivation of PI3K p110δ on the development of chronic allograft rejection in a murine model in which HY-mismatched male hearts were transplanted into female recipients. We show that suppression of p110δ activity significantly attenuates the development of chronic rejection of heart grafts in the absence of any additional immunosuppressive treatment by impairing the localization of antigen-specific T cells to the grafts, while not inducing specific T cell tolerance. p110δ pharmacologic inactivation is effective when initiated after transplantation. Targeting p110δ activity might be a viable strategy for the treatment of heart chronic rejection in humans.
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Affiliation(s)
- Huijun Ying
- Department of Immunology, Division of Medicine, Imperial College London, Hammersmith Campus, London, United Kingdom
| | - Hongmei Fu
- Department of Immunology, Division of Medicine, Imperial College London, Hammersmith Campus, London, United Kingdom
| | - Marlene L. Rose
- National Heart & Lung Institute, Division of Medicine, Imperial College London, Harefield Hospital, London, United Kingdom
| | - Ann M. McCormack
- National Heart & Lung Institute, Division of Medicine, Imperial College London, Harefield Hospital, London, United Kingdom
| | - Padmini Sarathchandra
- National Heart & Lung Institute, Division of Medicine, Imperial College London, Harefield Hospital, London, United Kingdom
| | - Klaus Okkenhaug
- Laboratory of Lymphocyte Signalling and Development, Babraham Institute, Cambridge, United Kingdom
| | - Federica M. Marelli-Berg
- Department of Immunology, Division of Medicine, Imperial College London, Hammersmith Campus, London, United Kingdom
- * E-mail:
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Abstract
Solid organ transplantation is the standard treatment to improve both the quality of life and survival in patients with various end-stage organ diseases. The primary barrier against successful transplantation is recipient alloimmunity and the need to be maintained on immunosuppressive therapies with associated side effects. Despite such treatments in renal transplantation, after death with a functioning graft, chronic allograft dysfunction (CAD) is the most common cause of late allograft loss. Recipient recognition of donor histocompatibility antigens, via direct, indirect, and semidirect pathways, is critically dependent on the antigen-presenting cell (APC) and elicits effector responses dominated by recipient T cells. In allograft rejection, the engagement of recipient and donor cells results in recruitment of T-helper (Th) cells of the Th1 and Th17 lineage to the graft. In cases in which the alloresponse is dominated by regulatory T cells (Tregs), rejection can be prevented and the allograft tolerated with minimum or no immunosuppression. Here, we review the pathways of allorecognition that underlie CAD and the T-cell effector phenotypes elicited as part of the alloresponse. Future therapies including depletion of donor-reactive lymphocytes, costimulation blockade, negative vaccination using dendritic cell subtypes, and Treg therapy are inferred from an understanding of these mechanisms of allograft rejection.
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Gökmen MR, Lombardi G, Lechler RI. The importance of the indirect pathway of allorecognition in clinical transplantation. Curr Opin Immunol 2008; 20:568-74. [PMID: 18655831 DOI: 10.1016/j.coi.2008.06.009] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Accepted: 06/26/2008] [Indexed: 12/01/2022]
Abstract
The immune system mounts a response to non-self transplanted tissue through a number of mechanisms. The indirect pathway of allorecognition, in which cells of the adaptive immune system recognize MHC alloantigen-derived peptide on self-MHC molecules, has emerged as a potent inducer of allograft rejection. In particular, recent evidence convincingly connects the indirect pathway with chronic rejection, including antibody-mediated and CD8(+) T cell-mediated rejection. However, the indirect pathway can also promote the generation of regulatory T cells, which have emerged as crucial suppressors of the alloresponse, and hold much promise in the quest for clinical tolerance. An improved understanding of the indirect pathway is likely to bring important benefits to transplant recipients.
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Affiliation(s)
- M Refik Gökmen
- Immunoregulation Laboratory, King's College London, 5th Floor, Southwark Wing, Guy's Hospital, Great Maze Pond, London SE1 9RT, United Kingdom.
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Gelman AE, Okazaki M, Lai J, Kornfeld CG, Kreisel FH, Richardson SB, Sugimoto S, Tietjens JR, Patterson GA, Krupnick AS, Kreisel D. CD4+ T lymphocytes are not necessary for the acute rejection of vascularized mouse lung transplants. THE JOURNAL OF IMMUNOLOGY 2008; 180:4754-62. [PMID: 18354199 DOI: 10.4049/jimmunol.180.7.4754] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Acute rejection continues to present a major obstacle to successful lung transplantation. Although CD4(+) T lymphocytes are critical for the rejection of some solid organ grafts, the role of CD4(+) T cells in the rejection of lung allografts is largely unknown. In this study, we demonstrate in a novel model of orthotopic vascularized mouse lung transplantation that acute rejection of lung allografts is independent of CD4(+) T cell-mediated allorecognition pathways. CD4(+) T cell-independent rejection occurs in the absence of donor-derived graft-resident hematopoietic APCs. Furthermore, blockade of the CD28/B7 costimulatory pathways attenuates acute lung allograft rejection in the absence of CD4(+) T cells, but does not delay acute rejection when CD4(+) T cells are present. Our results provide new mechanistic insight into the acute rejection of lung allografts and highlight the importance of identifying differences in pathways that regulate the rejection of various organs.
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Affiliation(s)
- Andrew E Gelman
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University, St Louis, MO 63110, USA
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14
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Abstract
Donor dendritic cells are potent but short-lived stimulators of early transplant rejection, and recipient antigen presenting cells presenting donor major histocompatibility complex peptides sustain immunoreactivity and contribute to chronic rejection. We briefly consider how CD4 T cells that recognize allopeptide can provide help for effector and regulatory responses and highlight the implications for promoting graft survival.
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Bolinger B, Krebs P, Tian Y, Engeler D, Scandella E, Miller S, Palmer DC, Restifo NP, Clavien PA, Ludewig B. Immunologic ignorance of vascular endothelial cells expressing minor histocompatibility antigen. Blood 2008; 111:4588-95. [PMID: 18195091 PMCID: PMC3403502 DOI: 10.1182/blood-2007-09-114769] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Accepted: 01/05/2008] [Indexed: 12/20/2022] Open
Abstract
Endothelial cells (ECs) presenting minor histocompatibility antigen (mhAg) are major target cells for alloreactive effector CD8(+) T cells during chronic transplant rejection and graft-versus-host disease (GVHD). The contribution of ECs to T-cell activation, however, is still a controversial issue. In this study, we have assessed the antigen-presenting capacity of ECs in vivo using a transgenic mouse model with beta-galactosidase (beta-gal) expression confined to the vascular endothelium (Tie2-LacZ mice). In a GVHD-like setting with adoptive transfer of beta-gal-specific T-cell receptor-transgenic T cells, beta-gal expression by ECs was not sufficient to either activate or tolerize CD8(+) T cells. Likewise, transplantation of fully vascularized heart or liver grafts from Tie2-LacZ mice into nontransgenic recipients did not suffice to activate beta-gal-specific CD8(+) T cells, indicating that CD8(+) T-cell responses against mhAg cannot be initiated by ECs. Moreover, we could show that spontaneous activation of beta-gal-specific CD8(+) T cells in Tie2-LacZ mice was exclusively dependent on CD11c(+) dendritic cells (DCs), demonstrating that mhAgs presented by ECs remain immunologically ignored unless presentation by DCs is granted.
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Erlebacher A, Vencato D, Price KA, Zhang D, Glimcher LH. Constraints in antigen presentation severely restrict T cell recognition of the allogeneic fetus. J Clin Invest 2007; 117:1399-411. [PMID: 17446933 PMCID: PMC1849983 DOI: 10.1172/jci28214] [Citation(s) in RCA: 179] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2006] [Accepted: 02/20/2007] [Indexed: 11/17/2022] Open
Abstract
How the fetus escapes rejection by the maternal immune system remains one of the major unsolved questions in transplantation immunology. Using a system to visualize both CD4+ and CD8+ T cell responses during pregnancy in mice, we find that maternal T cells become aware of the fetal allograft exclusively through "indirect" antigen presentation, meaning that T cell engagement requires the uptake and processing of fetal/placental antigen by maternal APCs. This reliance on a relatively minor allorecognition pathway removes a major threat to fetal survival, since it avoids engaging the large number of T cells that typically drive acute transplant rejection through their ability to directly interact with foreign MHC molecules. Furthermore, CD8+ T cells that indirectly recognize fetal/placental antigen undergo clonal deletion without priming for cytotoxic effector function and cannot induce antigen-specific fetal demise even when artificially activated. Antigen presentation commenced only at mid-gestation, in association with the endovascular invasion of placental trophoblasts and the hematogenous release of placental debris. Our results suggest that limited pathways of antigen presentation, in conjunction with tandem mechanisms of immune evasion, contribute to the unique immunological status of the fetus. The pronounced degree of T cell ignorance of the fetus also has implications for the pathophysiology of immune-mediated early pregnancy loss.
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Affiliation(s)
- Adrian Erlebacher
- Department of Pathology, Experimental Pathology Program, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA.
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