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Carbone F, Russo C, Colamatteo A, La Rocca C, Fusco C, Matarese A, Procaccini C, Matarese G. Cellular and molecular signaling towards T cell immunological self-tolerance. J Biol Chem 2024; 300:107134. [PMID: 38432631 PMCID: PMC10981134 DOI: 10.1016/j.jbc.2024.107134] [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] [Received: 11/15/2023] [Revised: 02/21/2024] [Accepted: 02/26/2024] [Indexed: 03/05/2024] Open
Abstract
The binding of a cognate antigen to T cell receptor (TCR) complex triggers a series of intracellular events controlling T cell activation, proliferation, and differentiation. Upon TCR engagement, different negative regulatory feedback mechanisms are rapidly activated to counterbalance T cell activation, thus preventing excessive signal propagation and promoting the induction of immunological self-tolerance. Both positive and negative regulatory processes are tightly controlled to ensure the effective elimination of foreign antigens while limiting surrounding tissue damage and autoimmunity. In this context, signals deriving from co-stimulatory molecules (i.e., CD80, CD86), co-inhibitory receptors (PD-1, CTLA-4), the tyrosine phosphatase CD45 and cytokines such as IL-2 synergize with TCR-derived signals to guide T cell fate and differentiation. The balance of these mechanisms is also crucial for the generation of CD4+ Foxp3+ regulatory T cells, a cellular subset involved in the control of immunological self-tolerance. This review provides an overview of the most relevant pathways induced by TCR activation combined with those derived from co-stimulatory and co-inhibitory molecules implicated in the cell-intrinsic modulation of T cell activation. In addition to the latter, we dissected mechanisms responsible for T cell-mediated suppression of immune cell activation through regulatory T cell generation, homeostasis, and effector functions. We also discuss how imbalanced signaling derived from TCR and accessory molecules can contribute to autoimmune disease pathogenesis.
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Affiliation(s)
- Fortunata Carbone
- Laboratorio di Immunologia, Istituto per l'Endocrinologia e l'Oncologia Sperimentale "G. Salvatore", Consiglio Nazionale delle Ricerche (IEOS-CNR), Napoli, Italy; Unità di Neuroimmunologia, IRCCS-Fondazione Santa Lucia, Roma, Italy
| | - Claudia Russo
- D.A.I. Medicina di Laboratorio e Trasfusionale, Azienda Ospedaliera Universitaria "Federico II", Napoli, Italy
| | - Alessandra Colamatteo
- Treg Cell Lab, Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli "Federico II", Napoli, Italy
| | - Claudia La Rocca
- Laboratorio di Immunologia, Istituto per l'Endocrinologia e l'Oncologia Sperimentale "G. Salvatore", Consiglio Nazionale delle Ricerche (IEOS-CNR), Napoli, Italy
| | - Clorinda Fusco
- Treg Cell Lab, Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli "Federico II", Napoli, Italy
| | - Alessandro Matarese
- Dipartimento di Medicina Clinica e Chirurgia, Università degli Studi di Napoli "Federico II", Naples, Italy
| | - Claudio Procaccini
- Laboratorio di Immunologia, Istituto per l'Endocrinologia e l'Oncologia Sperimentale "G. Salvatore", Consiglio Nazionale delle Ricerche (IEOS-CNR), Napoli, Italy; Unità di Neuroimmunologia, IRCCS-Fondazione Santa Lucia, Roma, Italy.
| | - Giuseppe Matarese
- Laboratorio di Immunologia, Istituto per l'Endocrinologia e l'Oncologia Sperimentale "G. Salvatore", Consiglio Nazionale delle Ricerche (IEOS-CNR), Napoli, Italy; Treg Cell Lab, Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli "Federico II", Napoli, Italy.
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2
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Santambrogio L, Franco A. The yin/yang balance of the MHC-self -immunopeptidome. Front Immunol 2022; 13:1035363. [PMID: 36405763 PMCID: PMC9666884 DOI: 10.3389/fimmu.2022.1035363] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 10/07/2022] [Indexed: 07/22/2023] Open
Abstract
The MHC-self immunopeptidome of professional antigen presenting cells is a cognate ligand for the TCRs expressed on both conventional and thymic-derived natural regulatory T cells. In regulatory T cells, the TCR signaling associated with MHC-peptide recognition induces antigen specific as well as bystander immunosuppression. On the other hand, TCR activation of conventional T cells is associated with protective immunity. As such the peripheral T cell repertoire is populated by a number of T cells with different phenotypes and different TCRs, which can recognize the same MHC-self-peptide complex, resulting in opposite immunological outcomes. This article summarizes what is known about regulatory and conventional T cell recognition of the MHC-self-immunopeptidome at steady state and in inflammatory conditions associated with increased T and B cell self-reactivity, discussing how changes in the MHC-ligandome including epitope copy number and post-translational modifications can tilt the balance toward the expansion of pro-inflammatory or regulatory T cells.
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Affiliation(s)
- Laura Santambrogio
- Department of Radiation Oncology, Physiology and Biophysics, Englander Institute of Precision Medicine, Weill Cornell Medicine, New York, NY, United States
| | - Alessandra Franco
- University of California San Diego School of Medicine, Department of Pediatrics, La Jolla, CA, United States
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3
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Wang C, Daley SR. How Thymocyte Deletion in the Cortex May Curtail Antigen-Specific T-Regulatory Cell Development in the Medulla. Front Immunol 2022; 13:892498. [PMID: 35693793 PMCID: PMC9176388 DOI: 10.3389/fimmu.2022.892498] [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] [Received: 03/09/2022] [Accepted: 04/26/2022] [Indexed: 11/13/2022] Open
Abstract
CD4+ T cell responses to self-antigens are pivotal for immunological self-tolerance. Activation of Foxp3– T-conventional (T-conv) cells can precipitate autoimmune disease, whereas activation of Foxp3+ T-regulatory (T-reg) cells is essential to prevent autoimmune disease. This distinction indicates the importance of the thymus in controlling the differentiation of self-reactive CD4+ T cells. Thymocytes and thymic antigen-presenting cells (APC) depend on each other for normal maturation and differentiation. In this Hypothesis and Theory article, we propose this mutual dependence dictates which self-antigens induce T-reg cell development in the thymic medulla. We postulate self-reactive CD4+ CD8– thymocytes deliver signals that stabilize and amplify the presentation of their cognate self-antigen by APC in the thymic medulla, thereby seeding a niche for the development of T-reg cells specific for the same self-antigen. By limiting the number of antigen-specific CD4+ thymocytes in the medulla, thymocyte deletion in the cortex may impede the formation of medullary T-reg niches containing certain self-antigens. Susceptibility to autoimmune disease may arise from cortical deletion creating a “hole” in the self-antigen repertoire recognized by T-reg cells.
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Affiliation(s)
- Chenglong Wang
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD, Australia
| | - Stephen R Daley
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, QLD, Australia
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4
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Yang K. Regulation of Treg Cell Metabolism and Function in Non-Lymphoid Tissues. Front Immunol 2022; 13:909705. [PMID: 35720275 PMCID: PMC9200993 DOI: 10.3389/fimmu.2022.909705] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 05/06/2022] [Indexed: 12/12/2022] Open
Abstract
Regulator T cells (Tregs) play pivotal roles in maintaining immune tolerance and regulating immune responses against pathogens and tumors. Reprogramming of cellular metabolism has been determined as a crucial process that connects microenvironmental cues and signaling networks to influence homeostasis and function of tissue Tregs. In adaptation to a variety of non-lymphoid tissues, Tregs coordinate local immune signals and signaling networks to rewire cellular metabolic programs to sustain their suppressive function. Altered Treg metabolism in turn shapes Treg activation and function. In light of the advanced understanding of immunometabolism, manipulation of systemic metabolites has been emerging as an attractive strategy aiming to modulate metabolism and function of tissue Tregs and improve the treatment of immune-related diseases. In this review, we summarize key immune signals and metabolic programs involved in the regulation of tissue Tregs, review the mechanisms underlying the differentiation and function of Tregs in various non-lymphoid tissues, and discuss therapeutic intervention of metabolic modulators of tissue Tregs for the treatment of autoimmune diseases and cancer.
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Affiliation(s)
- Kai Yang
- Department of Pediatrics and the Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, United States
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5
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Chen JW, Schickel JN, Tsakiris N, Sng J, Arbogast F, Bouis D, Parisi D, Gera R, Boeckers JM, Delmotte FR, Veselits M, Schuetz C, Jacobsen EM, Posovszky C, Schulz AS, Schwarz K, Clark MR, Menard L, Meffre E. Positive and negative selection shape the human naïve B cell repertoire. J Clin Invest 2021; 132:150985. [PMID: 34813502 PMCID: PMC8759783 DOI: 10.1172/jci150985] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 11/17/2021] [Indexed: 11/21/2022] Open
Abstract
Although negative selection of developing B cells in the periphery is well described, yet poorly understood, evidence of naive B cell positive selection remains elusive. Using 2 humanized mouse models, we demonstrate that there was strong skewing of the expressed immunoglobulin repertoire upon transit into the peripheral naive B cell pool. This positive selection of expanded naive B cells in humanized mice resembled that observed in healthy human donors and was independent of autologous thymic tissue. In contrast, negative selection of autoreactive B cells required thymus-derived Tregs and MHC class II–restricted self-antigen presentation by B cells. Indeed, both defective MHC class II expression on B cells of patients with rare bare lymphocyte syndrome and prevention of self-antigen presentation via HLA-DM inhibition in humanized mice resulted in the production of autoreactive naive B cells. These latter observations suggest that Tregs repressed autoreactive naive B cells continuously produced by the bone marrow. Thus, a model emerged, in which both positive and negative selection shaped the human naive B cell repertoire and that each process was mediated by fundamentally different molecular and cellular mechanisms.
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Affiliation(s)
- Jeff W Chen
- Department of Immunobiology, Yale University, New Haven, United States of America
| | | | - Nikolaos Tsakiris
- Department of Immunobiology, Yale University, New Haven, United States of America
| | - Joel Sng
- Department of Immunobiology, Yale University, New Haven, United States of America
| | - Florent Arbogast
- Department of Immunobiology, Yale University, New Haven, United States of America
| | - Delphine Bouis
- Department of Immunobiology, Yale University, New Haven, United States of America
| | - Daniele Parisi
- Department of Immunobiology, Yale University, New Haven, United States of America
| | - Ruchi Gera
- Department of Immunobiology, Yale University, New Haven, United States of America
| | - Joshua M Boeckers
- Department of Immunobiology, Yale University, New Haven, United States of America
| | - Fabien R Delmotte
- Department of Immunobiology, Yale University, New Haven, United States of America
| | - Margaret Veselits
- Department of Medicine, University of Chicago, Chicago, United States of America
| | - Catharina Schuetz
- Department of Pediatrics and Adolescent Medicine, Ulm University, Ulm, Germany
| | - Eva-Maria Jacobsen
- Department of Pediatrics and Adolescent Medicine, Ulm University, Ulm, Germany
| | - Carsten Posovszky
- Department of Pediatrics and Adolescent Medicine, Ulm University, Ulm, Germany
| | - Ansgar S Schulz
- Department of Pediatrics and Adolescent Medicine, Ulm University, Ulm, Germany
| | - Klaus Schwarz
- Department of Pediatrics and Adolescent Medicine, Ulm University, Ulm, Germany
| | - Marcus R Clark
- Department of Medicine, University of Chicago, Chicago, United States of America
| | - Laurence Menard
- Department of Immunobiology, Yale University, New Haven, United States of America
| | - Eric Meffre
- Department of Immunobiology, Yale University, New Haven, United States of America
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6
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Fulford TS, Grumont R, Wirasinha RC, Ellis D, Barugahare A, Turner SJ, Naeem H, Powell D, Lyons PA, Smith KGC, Scheer S, Zaph C, Klein U, Daley SR, Gerondakis S. c-Rel employs multiple mechanisms to promote the thymic development and peripheral function of regulatory T cells in mice. Eur J Immunol 2021; 51:2006-2026. [PMID: 33960413 DOI: 10.1002/eji.202048900] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 03/12/2021] [Accepted: 05/05/2021] [Indexed: 01/03/2023]
Abstract
The NF-κB transcription factor c-Rel is a critical regulator of Treg ontogeny, controlling multiple points of the stepwise developmental pathway. Here, we found that the thymic Treg defect in c-Rel-deficient (cRel-/- ) mice is quantitative, not qualitative, based on analyses of TCR repertoire and TCR signaling strength. However, these parameters are altered in the thymic Treg-precursor population, which is also markedly diminished in cRel-/- mice. Moreover, c-Rel governs the transcriptional programme of both thymic and peripheral Tregs, controlling a core of genes involved with immune signaling, and separately in the periphery, cell cycle progression. Last, the immune suppressive function of peripheral cRel-/- tTregs is diminished in a lymphopenic model of T cell proliferation and is associated with decreased stability of Foxp3 expression. Collectively, we show that c-Rel is a transcriptional regulator that controls multiple aspects of Treg development, differentiation, and function via distinct mechanisms.
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Affiliation(s)
- Thomas S Fulford
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Raelene Grumont
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Rushika C Wirasinha
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Darcy Ellis
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Adele Barugahare
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia.,Monash Bioinformatics Platform, School of Biomedical Sciences, Monash University, Melbourne, Australia
| | - Stephen J Turner
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia.,Department of Microbiology, Monash University, Melbourne, Australia
| | - Haroon Naeem
- Monash Bioinformatics Platform, School of Biomedical Sciences, Monash University, Melbourne, Australia
| | - David Powell
- Monash Bioinformatics Platform, School of Biomedical Sciences, Monash University, Melbourne, Australia
| | - Paul A Lyons
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge, England, UK.,Department of Medicine, University of Cambridge, University of Cambridge School of Clinical Medicine, Cambridge, England, UK
| | - Kenneth G C Smith
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge, England, UK.,Department of Medicine, University of Cambridge, University of Cambridge School of Clinical Medicine, Cambridge, England, UK
| | - Sebastian Scheer
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Colby Zaph
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Ulf Klein
- Division of Haematology & Immunology, Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, LS2 7TF
| | - Stephen R Daley
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
| | - Steve Gerondakis
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
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7
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Usharauli D, Kamala T. Could cross-reactivity rescue Foxp3+ regulatory T cell precursors from thymic deletion? Scand J Immunol 2020; 93:e12940. [PMID: 32776320 DOI: 10.1111/sji.12940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 07/06/2020] [Accepted: 07/17/2020] [Indexed: 11/28/2022]
Abstract
Thymocytes that bind with high affinity to peptides displayed by MHC class II (pMHC-II) are deleted while low-affinity binders differentiate into naive CD4+ T cells. However, Foxp3+ regulatory T cells (Tregs) seem to defy this binary choice as their precursors require high-affinity interaction with pMHC-II for maturation in the thymus. Here, we rely on the antigen-specific interpretive framework, SPIRAL (Specific ImmunoRegulatory Algorithm), to propose that Tregs escape thymic deletion by forming dyads with IL-2-producing T cells via antigen cross-reactivity. This interpretation reconciles contradictions related to Treg ontogeny in the thymus and their role in modulating antigen-specific immune responses.
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8
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Sng J, Ayoglu B, Chen JW, Schickel JN, Ferre EMN, Glauzy S, Romberg N, Hoenig M, Cunningham-Rundles C, Utz PJ, Lionakis MS, Meffre E. AIRE expression controls the peripheral selection of autoreactive B cells. Sci Immunol 2019; 4:eaav6778. [PMID: 30979797 PMCID: PMC7257641 DOI: 10.1126/sciimmunol.aav6778] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 03/04/2019] [Indexed: 12/13/2022]
Abstract
Autoimmune regulator (AIRE) mutations result in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) syndrome characterized by defective central T cell tolerance and the production of many autoantibodies targeting tissue-specific antigens and cytokines. By studying CD3- and AIRE-deficient patients, we found that lack of either T cells or AIRE function resulted in the peripheral accumulation of autoreactive mature naïve B cells. Proteomic arrays and Biacore affinity measurements revealed that unmutated antibodies expressed by these autoreactive naïve B cells recognized soluble molecules and cytokines including insulin, IL-17A, and IL-17F, which are AIRE-dependent thymic peripheral tissue antigens targeted by autoimmune responses in APECED. AIRE-deficient patients also displayed decreased frequencies of regulatory T cells (Tregs) that lacked common TCRβ clones found instead in their conventional T cell compartment, thereby suggesting holes in the Treg TCR repertoire of these patients. Hence, AIRE-mediated T cell/Treg selection normally prevents the expansion of autoreactive naïve B cells recognizing peripheral self-antigens.
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Affiliation(s)
- Joel Sng
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06511, USA
| | - Burcu Ayoglu
- School of Medicine, Division of Immunology and Rheumatology, Stanford University, Stanford, CA 94305, USA
| | - Jeff W Chen
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06511, USA
| | - Jean-Nicolas Schickel
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06511, USA
| | - Elise M N Ferre
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD USA
| | - Salomé Glauzy
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06511, USA
| | - Neil Romberg
- Division of Immunology and Allergy, Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Manfred Hoenig
- Department of Pediatrics, University Medical Centre Ulm, Ulm, Germany
| | - Charlotte Cunningham-Rundles
- Division of Allergy and Immunology, Department of Medicine, Icahn School of Medicine, Mount Sinai, New York, NY 10029, USA
| | - Paul J Utz
- School of Medicine, Division of Immunology and Rheumatology, Stanford University, Stanford, CA 94305, USA
- Institute for Immunity, Transplantation, and Infection (ITI), Stanford University, Stanford, CA 94305, USA
| | - Michail S Lionakis
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD USA
| | - Eric Meffre
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06511, USA.
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9
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Revealing the specificity of regulatory T cells in murine autoimmune diabetes. Proc Natl Acad Sci U S A 2018; 115:5265-5270. [PMID: 29712852 DOI: 10.1073/pnas.1715590115] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Regulatory T cells (Tregs) control organ-specific autoimmunity in a tissue antigen-specific manner, yet little is known about their specificity in a natural repertoire. In this study, we used the nonobese diabetic (NOD) mouse model of autoimmune diabetes to investigate the antigen specificity of Tregs present in the inflamed tissue, the islets of Langerhans. Compared with Tregs present in spleen and lymph node, Tregs in the islets showed evidence of antigen stimulation that correlated with higher proliferation and expression of activation markers CD103, ICOS, and TIGIT. T cell receptor (TCR) repertoire profiling demonstrated that islet Treg clonotypes are expanded in the islets, suggesting localized antigen-driven expansion in inflamed islets. To determine their specificity, we captured TCRαβ pairs from islet Tregs using single-cell TCR sequencing and found direct evidence that some of these TCRs were specific for islet-derived antigens including insulin B:9-23 and proinsulin. Consistently, insulin B:9-23 tetramers readily detected insulin-specific Tregs in the islets of NOD mice. Lastly, islet Tregs from prediabetic NOD mice were effective at preventing diabetes in Treg-deficient NOD.CD28-/- recipients. These results provide a glimpse into the specificities of Tregs in a natural repertoire that are crucial for opposing the progression of autoimmune diabetes.
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10
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Yen B, Fortson KT, Rothman NJ, Arpaia N, Reiner SL. Clonal Bifurcation of Foxp3 Expression Visualized in Thymocytes and T Cells. Immunohorizons 2018; 2:119-128. [PMID: 29707696 PMCID: PMC5922779 DOI: 10.4049/immunohorizons.1700064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Regulatory T cells (Tregs) are crucial for suppressing autoimmunity and inflammation mediated by conventional T cells. To be useful, some Tregs should have overlapping specificity with relevant self-reactive or pathogen-specific clones. Whether matching recognition between Tregs and non-Tregs might arise through stochastic or deterministic mechanisms has not been addressed. We tested the hypothesis that some Tregs that arise in the thymus or that are induced during Ag-driven expansion of conventional CD4+ T cells might be clonally related to non-Tregs by virtue of asymmetric Foxp3 induction during cell division. We isolated mouse CD4+ thymocytes dividing in vivo, wherein sibling cells exhibited discordant expression of Foxp3 and CD25. Under in vitro conditions that stimulate induced Tregs from conventional mouse CD4+ T cells, we found a requirement for cell cycle progression to achieve Foxp3 induction. Moreover, a substantial fraction of sibling cell pairs arising from induced Treg stimulation also contained discordant expression of Foxp3. Division-linked yet asymmetric induction of Treg fate offers potential mechanisms to anticipate peripheral self-reactivity during thymic selection as well as produce precise, de novo counterregulation during CD4+ T cell–mediated immune responses.
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Affiliation(s)
- Bonnie Yen
- Department of Microbiology and Immunology, College of Physicians and Surgeons of Columbia University, New York, NY 10032.,Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, NY 10032
| | - Katherine T Fortson
- Department of Microbiology and Immunology, College of Physicians and Surgeons of Columbia University, New York, NY 10032
| | - Nyanza J Rothman
- Department of Microbiology and Immunology, College of Physicians and Surgeons of Columbia University, New York, NY 10032.,Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, NY 10032
| | - Nicholas Arpaia
- Department of Microbiology and Immunology, College of Physicians and Surgeons of Columbia University, New York, NY 10032
| | - Steven L Reiner
- Department of Microbiology and Immunology, College of Physicians and Surgeons of Columbia University, New York, NY 10032.,Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, NY 10032
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11
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Hu DY, Wirasinha RC, Goodnow CC, Daley SR. IL-2 prevents deletion of developing T-regulatory cells in the thymus. Cell Death Differ 2017; 24:1007-1016. [PMID: 28362433 DOI: 10.1038/cdd.2017.38] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 02/21/2017] [Accepted: 02/27/2017] [Indexed: 12/12/2022] Open
Abstract
In the thymus, strongly self-reactive T cells may undergo apoptotic deletion or differentiate into Foxp3+ T-regulatory (T-reg) cells. Mechanisms that partition T cells into these two fates are unclear. Here, we show that IL-2 signalling is required to prevent deletion of CD4+ CD8- CCR7+ Helios+ thymocytes poised to upregulate Foxp3. The deletion prevented by IL-2 signalling is Foxp3 independent and occurs later in thymocyte development than the deletion that is prevented by Card11 signalling. Our results distinguish two bottlenecks at which strongly self-reactive thymocytes undergo deletion or progress to the next stage of T-reg differentiation; Card11 regulates the first bottleneck and IL-2 regulates the second.
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Affiliation(s)
- Daniel Y Hu
- Immunology Department, The John Curtin School of Medical Research, The Australian National University, Canberra 0200, Australia
| | - Rushika C Wirasinha
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC 3800, Australia
| | - Christopher C Goodnow
- Immunology Department, The John Curtin School of Medical Research, The Australian National University, Canberra 0200, Australia.,Immunology Division, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Stephen R Daley
- Immunology Department, The John Curtin School of Medical Research, The Australian National University, Canberra 0200, Australia.,Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC 3800, Australia
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12
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Daley SR, Teh C, Hu DY, Strasser A, Gray DH. Cell death and thymic tolerance. Immunol Rev 2017; 277:9-20. [DOI: 10.1111/imr.12532] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Stephen R. Daley
- Infection and Immunity Program; Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology; Monash University; Melbourne VIC Australia
| | - Charis Teh
- The Walter and Eliza Hall Institute of Medical Research; Melbourne VIC Australia
- Department of Medical Biology; The University of Melbourne; Parkville VIC Australia
| | | | - Andreas Strasser
- The Walter and Eliza Hall Institute of Medical Research; Melbourne VIC Australia
- Department of Medical Biology; The University of Melbourne; Parkville VIC Australia
| | - Daniel H.D. Gray
- The Walter and Eliza Hall Institute of Medical Research; Melbourne VIC Australia
- Department of Medical Biology; The University of Melbourne; Parkville VIC Australia
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13
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Abstract
Genetic and cellular studies of type 1 diabetes in patients and in the nonobese diabetic mouse model of type 1 diabetes point to an imbalance between effector T cells and regulatory T cells (Tregs) as a driver of the disease. The imbalance may arise as a consequence of genetically encoded defects in thymic deletion of islet antigen-specific T cells, induction of islet antigen-specific thymic Tregs, unfavorable tissue environment for peripheral Treg induction, and failure of islet antigen-specific Tregs to survive in the inflamed islets secondary to insufficient IL-2 signals. These understandings are the foundation for rationalized design of new therapeutic interventions to restore the balance by selectively targeting effector T cells and boosting Tregs.
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Affiliation(s)
- Allyson Spence
- Department of Surgery and UCSF Diabetes Center, University of California, 513 Parnassus HSE-520, Box 0780, San Francisco, CA, 94143, USA
| | - Qizhi Tang
- Department of Surgery and UCSF Diabetes Center, University of California, 513 Parnassus HSE-520, Box 0780, San Francisco, CA, 94143, USA.
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14
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T cell receptor signalling in the control of regulatory T cell differentiation and function. Nat Rev Immunol 2016; 16:220-33. [PMID: 27026074 DOI: 10.1038/nri.2016.26] [Citation(s) in RCA: 346] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Regulatory T cells (TReg cells), a specialized T cell lineage, have a pivotal function in the control of self tolerance and inflammatory responses. Recent studies have revealed a discrete mode of T cell receptor (TCR) signalling that regulates TReg cell differentiation, maintenance and function and that affects gene expression, metabolism, cell adhesion and migration of these cells. Here, we discuss the emerging understanding of TCR-guided differentiation of TReg cells in the context of their function in health and disease.
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15
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Nuclear transfer nTreg model reveals fate-determining TCR-β and novel peripheral nTreg precursors. Proc Natl Acad Sci U S A 2016; 113:E2316-25. [PMID: 27044095 DOI: 10.1073/pnas.1523664113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
To study the development and function of "natural-arising" T regulatory (nTreg) cells, we developed a novel nTreg model on pure nonobese diabetic background using epigenetic reprogramming via somatic cell nuclear transfer. On RAG1-deficient background, we found that monoclonal FoxP3(+)CD4(+)Treg cells developed in the thymus in the absence of other T cells. Adoptive transfer experiments revealed that the thymic niche is not a limiting factor in nTreg development. In addition, we showed that the T-cell receptor (TCR) β-chain of our nTreg model was not only sufficient to bias T-cell development toward the CD4 lineage, but we also demonstrated that this TCR β-chain was able to provide stronger TCR signals. This TCR-β-driven mechanism would thus unify former per se contradicting hypotheses of TCR-dependent and -independent nTreg development. Strikingly, peripheral FoxP3(-)CD4(+)T cells expressing the same TCR as this somatic cell nuclear transfer nTreg model had a reduced capability to differentiate into Th1 cells but were poised to differentiate better into induced nTreg cells, both in vitro and in vivo, representing a novel peripheral precursor subset of nTreg cells to which we refer to as pre-nTreg cells.
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16
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A timeline demarcating two waves of clonal deletion and Foxp3 upregulation during thymocyte development. Immunol Cell Biol 2015; 94:357-66. [DOI: 10.1038/icb.2015.95] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 10/06/2015] [Accepted: 10/11/2015] [Indexed: 12/12/2022]
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17
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Weissler KA, Garcia V, Kropf E, Aitken M, Bedoya F, Wolf AI, Erikson J, Caton AJ. Distinct modes of antigen presentation promote the formation, differentiation, and activity of foxp3+ regulatory T cells in vivo. THE JOURNAL OF IMMUNOLOGY 2015; 194:3784-97. [PMID: 25780041 DOI: 10.4049/jimmunol.1402960] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 02/12/2015] [Indexed: 11/19/2022]
Abstract
How the formation and activity of CD4(+)Foxp3(+) regulatory T cells (Tregs) are shaped by TCR recognition of the diverse array of peptide:MHC complexes that can be generated from self-antigens and/or foreign Ags in vivo remains poorly understood. We show that a self-peptide with low (but not high) stimulatory potency promotes thymic Treg formation and can induce conventional CD4(+) T cells in the periphery to become Tregs that express different levels of the transcription factor Helios according to anatomical location. When Tregs generated in response to this self-peptide subsequently encountered the same peptide derived instead from influenza virus in the lung-draining lymph nodes of infected mice, they proliferated, acquired a T-bet(+)CXCR3(+) phenotype, and suppressed the antiviral effector T cell response in the lungs. However, these self-antigen-selected Tregs were unable to suppress the antiviral immune response based on recognition of the peptide as a self-antigen rather than a viral Ag. Notably, when expressed in a more immunostimulatory form, the self-peptide inhibited the formation of T-bet(+)CXCR3(+) Tregs in response to viral Ag, and Ag-expressing B cells from these mice induced Treg division without upregulation of CXCR3. These studies show that a weakly immunostimulatory self-peptide can induce thymic and peripheral Foxp3(+) Treg formation but is unable to activate self-antigen-selected Tregs to modulate an antiviral immune response. Moreover, a strongly immunostimulatory self-peptide expressed by B cells induced Tregs to proliferate without acquiring an effector phenotype that allows trafficking from the draining lymph node to the lungs and, thereby, prevented the Tregs from suppressing the antiviral immune response.
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Affiliation(s)
| | | | | | | | | | | | - Jan Erikson
- The Wistar Institute, Philadelphia, PA 19104
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18
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Huang W, August A. The signaling symphony: T cell receptor tunes cytokine-mediated T cell differentiation. J Leukoc Biol 2015; 97:477-85. [PMID: 25525115 PMCID: PMC4338847 DOI: 10.1189/jlb.1ri0614-293r] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 11/03/2014] [Accepted: 11/13/2014] [Indexed: 01/07/2023] Open
Abstract
T cell development, differentiation, and maintenance are orchestrated by 2 key signaling axes: the antigen-specific TCR and cytokine-mediated signals. The TCR signals the recognition of self- and foreign antigens to control T cell homeostasis for immune tolerance and immunity, which is regulated by a variety of cytokines to determine T cell subset homeostasis and differentiation. TCR signaling can synergize with or antagonize cytokine-mediated signaling to fine tune T cell fate; however, the latter is less investigated. Murine models with attenuated TCR signaling strength have revealed that TCR signaling can function as regulatory feedback machinery for T cell homeostasis and differentiation in differential cytokine milieus, such as IL-2-mediated Treg development; IL-7-mediated, naïve CD8(+) T cell homeostasis; and IL-4-induced innate memory CD8(+) T cell development. In this review, we discuss the symphonic cross-talk between TCR and cytokine-mediated responses that differentially control T cell behavior, with a focus on the negative tuning by TCR activation on the cytokine effects.
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Affiliation(s)
- Weishan Huang
- Department of Microbiology and Immunology, Cornell University, Ithaca, New York, USA
| | - Avery August
- Department of Microbiology and Immunology, Cornell University, Ithaca, New York, USA
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19
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Abstract
Induction of specific immune tolerance to grafts remains the sought-after standard following transplantation. Defined by expression of the Foxp3 (forkhead box protein 3) transcription factor, the regulatory T-cell (Treg) lineage has been noted to exert potent immunoregulatory functions that contribute to specific graft tolerance. In this review, we discuss the known signals and pathways which govern Treg development, both in the thymus and in peripheral sites, as well as lineage maintenance and homeostasis. In particular, we highlight the roles of T-cell receptor signaling, CD28 costimulation, and signals through phosphatidyl inositol 3-kinase (PI3K) and related metabolic pathways in multiple aspects of Treg biology.
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Affiliation(s)
- Alexandria Huynh
- Division of Medical Sciences, Harvard Medical School, Boston, MA, USA; Transplantation Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
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20
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Weissler KA, Caton AJ. The role of T-cell receptor recognition of peptide:MHC complexes in the formation and activity of Foxp3⁺ regulatory T cells. Immunol Rev 2014; 259:11-22. [PMID: 24712456 DOI: 10.1111/imr.12177] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Foxp3(+) regulatory T (Treg) cells are required to prevent the immune system from spontaneously mounting a severe autoaggressive lymphoproliferative disease and can modulate immune responses in a variety of settings, including infections. In this review, we describe studies that use transgenic mice to determine how signals through the T-cell receptor (TCR) contribute to the development, differentiation, and activity of Treg cells in in vivo settings. By varying the amount and quality of the self-peptide recognized by an autoreactive TCR, we have shown that the interplay between autoreactive thymocyte deletion and Treg cell formation leads to a Treg cell repertoire that is biased toward low abundance agonist self-peptides. In an autoimmune disease setting, we have demonstrated that diverse TCR specificities can be required in order for Treg cells to prevent disease in a mouse model of autoimmune inflammatory arthritis. Lastly, we have shown that Treg cells initially selected based on specificity for a self-peptide can be activated by TCR recognition of a viral peptide, and that they can acquire a specialized phenotype and suppress antiviral effector cell activity at the site of infection. These studies provide insights into the pivotal role that TCR specificity plays in the formation and activity of Treg cells.
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21
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Meyer zu Hörste G, Cordes S, Mausberg AK, Zozulya AL, Wessig C, Sparwasser T, Mathys C, Wiendl H, Hartung HP, Kieseier BC. FoxP3+ regulatory T cells determine disease severity in rodent models of inflammatory neuropathies. PLoS One 2014; 9:e108756. [PMID: 25286182 PMCID: PMC4186754 DOI: 10.1371/journal.pone.0108756] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 08/25/2014] [Indexed: 01/17/2023] Open
Abstract
Inflammatory neuropathies represent disabling human autoimmune disorders with considerable disease variability. Animal models provide insights into defined aspects of their disease pathogenesis. Forkhead box P3 (FoxP3)+ regulatory T lymphocytes (Treg) are anti-inflammatory cells that maintain immune tolerance and counteract tissue damage in a variety of immune-mediated disorders. Dysfunction or a reduced frequency of Tregs have been associated with different human autoimmune disorders. We here analyzed the functional relevance of Tregs in determining disease manifestation and severity in murine models of autoimmune neuropathies. We took advantage of the DEREG mouse system allowing depletion of Treg with high specificity as well as anti-CD25 directed antibodies to deplete Tregs in mice in actively induced experimental autoimmune neuritis (EAN). Furthermore antibody-depletion was performed in an adoptive transfer model of chronic neuritis. Early Treg depletion increased clinical EAN severity both in active and adoptive transfer chronic neuritis. This was accompanied by increased proliferation of myelin specific T cells and histological signs of peripheral nerve inflammation. Late stage Treg depletion after initial disease manifestation however did not exacerbate inflammatory neuropathy symptoms further. We conclude that Tregs determine disease severity in experimental autoimmune neuropathies during the initial priming phase, but have no major disease modifying function after disease manifestation. Potential future therapeutic approaches targeting Tregs should thus be performed early in inflammatory neuropathies.
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Affiliation(s)
- Gerd Meyer zu Hörste
- Department of Neurology, Heinrich-Heine-University, Medical Faculty, Düsseldorf, Germany
- * E-mail:
| | - Steffen Cordes
- Department of Neurology, Heinrich-Heine-University, Medical Faculty, Düsseldorf, Germany
| | - Anne K. Mausberg
- Department of Neurology, Heinrich-Heine-University, Medical Faculty, Düsseldorf, Germany
| | - Alla L. Zozulya
- Department of Neurology, Julius-Maximilians-University, Würzburg, Germany
| | - Carsten Wessig
- Department of Neurology, Julius-Maximilians-University, Würzburg, Germany
| | - Tim Sparwasser
- Institute for Infection Immunology, TWINCORE, Center for Experimental and Clinical Infection Research, Hannover, Germany
| | - Christian Mathys
- Department of Diagnostic and Interventional Radiology, Heinrich-Heine-University, Medical Faculty, Düsseldorf, Germany
| | - Heinz Wiendl
- Department of Neurology, University of Münster, Münster, Germany
| | - Hans-Peter Hartung
- Department of Neurology, Heinrich-Heine-University, Medical Faculty, Düsseldorf, Germany
| | - Bernd C. Kieseier
- Department of Neurology, Heinrich-Heine-University, Medical Faculty, Düsseldorf, Germany
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22
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Abstract
The peripheral T cell repertoire is sculpted from prototypic T cells in the thymus bearing randomly generated T cell receptors (TCR) and by a series of developmental and selection steps that remove cells that are unresponsive or overly reactive to self-peptide–MHC complexes. The challenge of understanding how the kinetics of T cell development and the statistics of the selection processes combine to provide a diverse but self-tolerant T cell repertoire has invited quantitative modeling approaches, which are reviewed here.
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Affiliation(s)
- Andrew J Yates
- Departments of Systems and Computational Biology, Microbiology and Immunology, Albert Einstein College of Medicine , New York, NY , USA
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23
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Delacher M, Schreiber L, Richards DM, Farah C, Feuerer M, Huehn J. Transcriptional control of regulatory T cells. Curr Top Microbiol Immunol 2014; 381:83-124. [PMID: 24831347 DOI: 10.1007/82_2014_373] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Regulatory T cells (Tregs) constitute unique T cell lineage that plays a key role for immunological tolerance. Tregs are characterized by the expression of the forkhead box transcription factor Foxp3, which acts as a lineage-specifying factor by determining the unique suppression profile of these immune cells. Here, we summarize the recent progress in understanding how Foxp3 expression itself is epigenetically and transcriptionally controlled, how the Treg-specific signature is achieved and how unique properties of Treg subsets are defined by other transcription factors. Finally, we will discuss recent studies focusing on the molecular targeting of Tregs to utilize the specific properties of this unique cell type in therapeutic settings.
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Affiliation(s)
- Michael Delacher
- Immune Tolerance, Tumor Immunology Program, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
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24
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Caton AJ, Kropf E, Simons DM, Aitken M, Weissler KA, Jordan MS. Strength of TCR signal from self-peptide modulates autoreactive thymocyte deletion and Foxp3(+) Treg-cell formation. Eur J Immunol 2013; 44:785-93. [PMID: 24307208 DOI: 10.1002/eji.201343767] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 10/09/2013] [Accepted: 11/26/2013] [Indexed: 11/11/2022]
Abstract
Autoreactive CD4(+) CD8(-) (CD4SP) thymocytes can be subjected to deletion when they encounter self-peptide during their development, but they can also undergo selection to become CD4SPFoxp3(+) Treg cells. We have analyzed the relationship between these distinct developmental fates using mice in which signals transmitted by the TCR have been attenuated by mutation of a critical tyrosine residue of the adapter protein SLP-76. In mice containing polyclonal TCR repertoires, the mutation caused increased frequencies of CD4SPFoxp3(+) thymocytes. CD4SP thymocytes expressing TCR Vβ-chains that are subjected to deletion by endogenous retroviral superantigens were also present at increased frequencies, particularly among Foxp3(+) thymocytes. In transgenic mice in which CD4SP thymocytes expressing an autoreactive TCR undergo both deletion and Treg-cell formation in response to a defined self-peptide, SLP-76 mutation abrogated deletion of autoreactive CD4SP thymocytes. Notably, Foxp3(+) Treg-cell formation still occurred, albeit with a reduced efficiency, and the mutation was also associated with decreased Nur77 expression by the autoreactive CD4SP thymocytes. These studies provide evidence that the strength of the TCR signal can play a direct role in directing the extent of both thymocyte deletion and Treg-cell differentiation, and suggest that distinct TCR signaling thresholds and/or pathways can promote CD4SP thymocyte deletion versus Treg-cell formation.
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25
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Bains I, van Santen HM, Seddon B, Yates AJ. Models of self-peptide sampling by developing T cells identify candidate mechanisms of thymic selection. PLoS Comput Biol 2013; 9:e1003102. [PMID: 23935465 PMCID: PMC3723501 DOI: 10.1371/journal.pcbi.1003102] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 05/01/2013] [Indexed: 11/18/2022] Open
Abstract
Conventional and regulatory T cells develop in the thymus where they are exposed to samples of self-peptide MHC (pMHC) ligands. This probabilistic process selects for cells within a range of responsiveness that allows the detection of foreign antigen without excessive responses to self. Regulatory T cells are thought to lie at the higher end of the spectrum of acceptable self-reactivity and play a crucial role in the control of autoimmunity and tolerance to innocuous antigens. While many studies have elucidated key elements influencing lineage commitment, we still lack a full understanding of how thymocytes integrate signals obtained by sampling self-peptides to make fate decisions. To address this problem, we apply stochastic models of signal integration by T cells to data from a study quantifying the development of the two lineages using controllable levels of agonist peptide in the thymus. We find two models are able to explain the observations; one in which T cells continually re-assess fate decisions on the basis of multiple summed proximal signals from TCR-pMHC interactions; and another in which TCR sensitivity is modulated over time, such that contact with the same pMHC ligand may lead to divergent outcomes at different stages of development. Neither model requires that T(conv) and T(reg) are differentially susceptible to deletion or that the two lineages need qualitatively different signals for development, as have been proposed. We find additional support for the variable-sensitivity model, which is able to explain apparently paradoxical observations regarding the effect of partial and strong agonists on T(conv) and T(reg) development.
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Affiliation(s)
- Iren Bains
- Immune Cell Biology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, New York, New York, United States of America
| | - Hisse M. van Santen
- Centro Biologia Molecular Severo Ochoa, CSIC/Universidad Autonoma de Madrid, Madrid, Spain
| | - Benedict Seddon
- Immune Cell Biology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom
| | - Andrew J. Yates
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, New York, New York, United States of America
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, New York, United States of America
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26
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Bailey M, Christoforidou Z, Lewis M. Evolution of immune systems: Specificity and autoreactivity. Autoimmun Rev 2013. [DOI: 10.1016/j.autrev.2012.10.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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27
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Daley SR, Hu DY, Goodnow CC. Helios marks strongly autoreactive CD4+ T cells in two major waves of thymic deletion distinguished by induction of PD-1 or NF-κB. ACTA ACUST UNITED AC 2013; 210:269-85. [PMID: 23337809 PMCID: PMC3570102 DOI: 10.1084/jem.20121458] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Expression of the transcription factor Helios identifies thymocyte divergence during positive and negative selection. Acquisition of self-tolerance in the thymus requires T cells to discriminate strong versus weak T cell receptor binding by self-peptide–MHC complexes. We find this discrimination is reported by expression of the transcription factor Helios, which is induced during negative selection but decreases during positive selection. Helios and the proapoptotic protein Bim were coinduced in 55% of nascent CCR7− CD4+ CD69+ thymocytes. These were short-lived cells that up-regulated PD-1 and down-regulated CD4 and CD8 during Bim-dependent apoptosis. Helios and Bim were also coinduced at the subsequent CCR7+ CD4+ CD69+ CD8− stage, and this second wave of Bim-dependent negative selection involved 20% of nascent cells. Unlike CCR7− counterparts, Helios+ CCR7+ CD4+ cells mount a concurrent Card11- and c-Rel–dependent activation response that opposes Bim-mediated apoptosis. This “hollow” activation response consists of many NF-κB target genes but lacks key growth mediators like IL-2 and Myc, and the thymocytes were not induced to proliferate. These findings identify Helios as the first marker known to diverge during positive and negative selection of thymocytes and reveal the extent, stage, and molecular nature of two distinct waves of clonal deletion in the normal thymus.
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Affiliation(s)
- Stephen R Daley
- Department of Immunology, The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory 0200, Australia
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28
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Regulatory T cells are strong promoters of acute ischemic stroke in mice by inducing dysfunction of the cerebral microvasculature. Blood 2012; 121:679-91. [PMID: 23160472 DOI: 10.1182/blood-2012-04-426734] [Citation(s) in RCA: 269] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We have recently identified T cells as important mediators of ischemic brain damage, but the contribution of the different T-cell subsets is unclear. Forkhead box P3 (FoxP3)-positive regulatory T cells (Tregs) are generally regarded as prototypic anti-inflammatory cells that maintain immune tolerance and counteract tissue damage in a variety of immune-mediated disorders. In the present study, we examined the role of Tregs after experimental brain ischemia/reperfusion injury. Selective depletion of Tregs in the DEREG mouse model dramatically reduced infarct size and improved neurologic function 24 hours after stroke and this protective effect was preserved at later stages of infarct development. The specificity of this detrimental Treg effect was confirmed by adoptive transfer experiments in wild-type mice and in Rag1(-/-) mice lacking lymphocytes. Mechanistically, Tregs induced microvascular dysfunction in vivo by increased interaction with the ischemic brain endothelium via the LFA-1/ICAM-1 pathway and platelets and these findings were confirmed in vitro. Ablation of Tregs reduced microvascular thrombus formation and improved cerebral reperfusion on stroke, as revealed by ultra-high-field magnetic resonance imaging at 17.6 Tesla. In contrast, established immunoregulatory characteristics of Tregs had no functional relevance. We define herein a novel and unexpected role of Tregs in a primary nonimmunologic disease state.
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29
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Abstract
Regulatory T cells expressing the FoxP3 transcription factor have a profound and nonredundant role in several aspects of immunological tolerance. We will review here the specification of this lineage, its population dynamics, and the diversity of subphenotypes that correlate with their diverse roles in controlling inflammation in a variety of settings.
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Affiliation(s)
- Christophe Benoist
- Division of Immunology, Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
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30
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Abstract
PURPOSE OF REVIEW Only recently has it been realized that immune mechanisms contribute to the pathophysiology of ischemic stroke, which for many years was regarded mainly as a vascular disease. These immunologic processes are present during all stages of stroke and involve both the innate and adaptive immune systems. This review highlights the latest findings related to the 'immunology of stroke'. RECENT FINDINGS During the early phase of an ischemic insult, 'danger signals' such as ATP are released from dying tissue to subsequently attract inflammatory cells. Unexpectedly, T cells have been identified as prominent mediators of stroke-induced tissue damage. Whereas during the acute stage of infarction T cells act independently from antigen-specific stimuli but rather interact with thrombotic pathways, antigen-dependent T-cell activation might be relevant at later stages. Moreover, certain T-cell subsets like γδ T cells or regulatory T cells are able to influence stroke outcome either in a detrimental or beneficial way. Finally, proof-of-principle studies using FTY720 or VLA-4 blockers have demonstrated that the concept of 'immunomodulation in stroke' is feasible. SUMMARY The insight that ischemic stroke at least in part is an immune-mediated disease may open new avenues for the treatment of this devastating neurologic condition.
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31
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Lee HM, Bautista JL, Scott-Browne J, Mohan JF, Hsieh CS. A broad range of self-reactivity drives thymic regulatory T cell selection to limit responses to self. Immunity 2012; 37:475-86. [PMID: 22921379 DOI: 10.1016/j.immuni.2012.07.009] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Revised: 05/18/2012] [Accepted: 07/10/2012] [Indexed: 12/28/2022]
Abstract
The degree of T cell self-reactivity considered dangerous by the immune system, thereby requiring thymic selection processes to prevent autoimmunity, is unknown. Here, we analyzed a panel of T cell receptors (TCRs) with a broad range of reactivity to ovalbumin (OVA(323-339)) in the rat insulin promoter (RIP)-mOVA self-antigen model for their ability to trigger thymic self-tolerance mechanisms. Thymic regulatory T (Treg) cell generation in vivo was directly correlated with in vitro TCR reactivity to OVA-peptide in a broad ~1,000-fold range. Interestingly, higher TCR affinity was associated with a larger Treg cell developmental "niche" size, even though the amount of antigen should remain constant. The TCR-reactivity threshold to elicit thymic negative selection and peripheral T cell responses was ~100-fold higher than that of Treg cell differentiation. Thus, these data suggest that the broad range of self-reactivity that elicits thymic Treg cell generation is tuned to secure peripheral tolerance to self.
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Affiliation(s)
- Hyang-Mi Lee
- Department of Internal Medicine, Division of Rheumatology, Washington University School of Medicine, St. Louis, MO 63110, USA
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32
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Abstract
The generation of regulatory T (T(Reg)) cells in the thymus is crucial for immune homeostasis and self-tolerance. Recent discoveries have revealed the cellular and molecular mechanisms that govern the differentiation of a subset of developing thymocytes into natural T(Reg) cells. Several models, centred on the self-reactivity of the T cell receptor (TCR), have been proposed to explain the generation of a T(Reg) cell population that is cognizant of self. Several molecular pathways link TCR and cytokine signalling with the expression of the T(Reg) cell-associated transcription factor forkhead box P3 (FOXP3). Moreover, interplay between thymocytes and thymic antigen-presenting cells is also involved in T(Reg) cell generation.
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33
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Distinct influences of peptide-MHC quality and quantity on in vivo T-cell responses. Proc Natl Acad Sci U S A 2012; 109:881-6. [PMID: 22223661 DOI: 10.1073/pnas.1119763109] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The strength of T-cell receptor (TCR) stimulation and subsequent T-cell response depend on a combination of peptide-major histocompatibility complex (pMHC) density and potency. By comparing two different pMHC at doses yielding similar proliferation in vivo, we have highlighted unexpected differences in the qualitative and quantitative effects of TCR ligand. Measurements of cytokine sensitivity and two-photon imaging of T cell-dendritic cell (T-DC) interactions reveal discrimination between comparably weak stimuli resulting from either decreased pMHC potency or pMHC density. In addition, TCR-induced genes in broad gene expression profiles segregate into two groups: one that responds to cumulative TCR signal and another that responds to pMHC quality, independent of quantity. These observations suggest that models of TCR ligand discrimination must account for disparate sensitivity of downstream responses to specific influences of pMHC potency.
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