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Lo WL, Huseby ES. The partitioning of TCR repertoires by thymic selection. J Exp Med 2024; 221:e20230897. [PMID: 39167074 PMCID: PMC11338286 DOI: 10.1084/jem.20230897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 05/22/2024] [Accepted: 07/09/2024] [Indexed: 08/23/2024] Open
Abstract
αβ T cells are critical components of the adaptive immune system; they maintain tissue and immune homeostasis during health, provide sterilizing immunity after pathogen infection, and are capable of eliminating transformed tumor cells. Fundamental to these distinct functions is the ligand specificity of the unique antigen receptor expressed on each mature T cell (TCR), which endows lymphocytes with the ability to behave in a cell-autonomous, disease context-specific manner. Clone-specific behavioral properties are initially established during T cell development when thymocytes use TCR recognition of major histocompatibility complex (MHC) and MHC-like ligands to instruct survival versus death and to differentiate into a plethora of inflammatory and regulatory T cell lineages. Here, we review the ligand specificity of the preselection thymocyte repertoire and argue that developmental stage-specific alterations in TCR signaling control cross-reactivity and foreign versus self-specificity of T cell sublineages.
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Affiliation(s)
- Wan-Lin Lo
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Eric S Huseby
- Department of Pathology, University of Massachusetts Chan Medical School, Worcester, MA, USA
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2
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Pircher H, Pinschewer DD, Boehm T. MHC I tetramer staining tends to overestimate the number of functionally relevant self-reactive CD8 T cells in the preimmune repertoire. Eur J Immunol 2023; 53:e2350402. [PMID: 37179469 DOI: 10.1002/eji.202350402] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 04/19/2023] [Accepted: 05/09/2023] [Indexed: 05/15/2023]
Abstract
Previous studies that used peptide-MHC (pMHC) tetramers (tet) to identify self-specific T cells have questioned the effectiveness of thymic-negative selection. Here, we used pMHCI tet to enumerate CD8 T cells specific for the immunodominant gp33 epitope of lymphocytic choriomeningitis virus glycoprotein (GP) in mice transgenically engineered to express high levels of GP as a self-antigen in the thymus. In GP-transgenic mice (GP+ ), monoclonal P14 TCR+ CD8 T cells that express a GP-specific TCR could not be detected by gp33/Db -tet staining, indicative of their complete intrathymic deletion. By contrast, in the same GP+ mice, substantial numbers of polyclonal CD8 T cells identifiable by gp33/Db -tet were present. The gp33-tet staining profiles of polyclonal T cells from GP+ and GP-negative (GP- ) mice were overlapping, but mean fluorescence intensities were ∼15% lower in cells from GP+ mice. Remarkably, the gp33-tet+ T cells in GP+ mice failed to clonally expand after lymphocytic choriomeningitis virus infection, whereas those of GP- mice did so. In Nur77GFP -reporter mice, dose-dependent responses to gp33 peptide-induced TCR stimulation revealed that gp33-tet+ T cells with high ligand sensitivity are lacking in GP+ mice. Hence, pMHCI tet staining identifies self-specific CD8 T cells but tends to overestimate the number of truly self-reactive cells.
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Affiliation(s)
- Hanspeter Pircher
- Department of Developmental Immunology, Max Planck Institute of Immunobiology and Epigenetics, Freiburg im Breisgau, Germany
| | - Daniel D Pinschewer
- Division of Experimental Virology, Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Thomas Boehm
- Department of Developmental Immunology, Max Planck Institute of Immunobiology and Epigenetics, Freiburg im Breisgau, Germany
- Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
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3
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Stadinski BD, Cleveland SB, Brehm MA, Greiner DL, Huseby PG, Huseby ES. I-A g7 β56/57 polymorphisms regulate non-cognate negative selection to CD4 + T cell orchestrators of type 1 diabetes. Nat Immunol 2023; 24:652-663. [PMID: 36807641 PMCID: PMC10623581 DOI: 10.1038/s41590-023-01441-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 01/20/2023] [Indexed: 02/22/2023]
Abstract
Genetic susceptibility to type 1 diabetes is associated with homozygous expression of major histocompatibility complex class II alleles that carry specific beta chain polymorphisms. Why heterozygous expression of these major histocompatibility complex class II alleles does not confer a similar predisposition is unresolved. Using a nonobese diabetic mouse model, here we show that heterozygous expression of the type 1 diabetes-protective allele I-Ag7 β56P/57D induces negative selection to the I-Ag7-restricted T cell repertoire, including beta-islet-specific CD4+ T cells. Surprisingly, negative selection occurs despite I-Ag7 β56P/57D having a reduced ability to present beta-islet antigens to CD4+ T cells. Peripheral manifestations of non-cognate negative selection include a near complete loss of beta-islet-specific CXCR6+ CD4+ T cells, an inability to cross-prime islet-specific glucose-6-phosphatase catalytic subunit-related protein and insulin-specific CD8+ T cells and disease arrest at the insulitis stage. These data reveal that negative selection on non-cognate self-antigens in the thymus can promote T cell tolerance and protection from autoimmunity.
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Affiliation(s)
- Brian D Stadinski
- Department of Pathology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Sarah B Cleveland
- Department of Pathology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Michael A Brehm
- Department of Molecular Medicine, Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, MA, USA
| | - Dale L Greiner
- Department of Molecular Medicine, Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, MA, USA
| | - Priya G Huseby
- Department of Pathology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Eric S Huseby
- Department of Pathology, University of Massachusetts Medical School, Worcester, MA, USA.
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4
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Tamaru T, Hattori M, Ninomiya Y, Kawamura G, Varès G, Honda K, Mishra DP, Wang B, Benjamin I, Sassone-Corsi P, Ozawa T, Takamatsu K. ROS stress resets circadian clocks to coordinate pro-survival signals. PLoS One 2013; 8:e82006. [PMID: 24312621 PMCID: PMC3846904 DOI: 10.1371/journal.pone.0082006] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 10/20/2013] [Indexed: 01/04/2023] Open
Abstract
Dysfunction of circadian clocks exacerbates various diseases, in part likely due to impaired stress resistance. It is unclear how circadian clock system responds toward critical stresses, to evoke life-protective adaptation. We identified a reactive oxygen species (ROS), H2O2 -responsive circadian pathway in mammals. Near-lethal doses of ROS-induced critical oxidative stress (cOS) at the branch point of life and death resets circadian clocks, synergistically evoking protective responses for cell survival. The cOS-triggered clock resetting and pro-survival responses are mediated by transcription factor, central clock-regulatory BMAL1 and heat shock stress-responsive (HSR) HSF1. Casein kinase II (CK2) –mediated phosphorylation regulates dimerization and function of BMAL1 and HSF1 to control the cOS-evoked responses. The core cOS-responsive transcriptome includes CK2-regulated crosstalk between the circadian, HSR, NF-kappa-B-mediated anti-apoptotic, and Nrf2-mediated anti-oxidant pathways. This novel circadian-adaptive signaling system likely plays fundamental protective roles in various ROS-inducible disorders, diseases, and death.
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Affiliation(s)
- Teruya Tamaru
- Department of Physiology & Advanced Research Center for Medical Science, Toho University School of Medicine, Tokyo, Japan
- * E-mail: (TT); (TO)
| | - Mitsuru Hattori
- Department of Chemistry, School of Science, The University of Tokyo, Tokyo, Japan
| | - Yasuharu Ninomiya
- Research Center for Radiation Protection, National Institute of Radiological Science, Chiba, Japan
| | - Genki Kawamura
- Department of Chemistry, School of Science, The University of Tokyo, Tokyo, Japan
| | - Guillaume Varès
- Research Center for Radiation Protection, National Institute of Radiological Science, Chiba, Japan
| | - Kousuke Honda
- Department of Chemistry, School of Science, The University of Tokyo, Tokyo, Japan
| | - Durga Prasad Mishra
- Cell Death Research Laboratory, Endocrinology Division, CSIR-Central Drug Research Institute, Lucknow, India
| | - Bing Wang
- Research Center for Radiation Protection, National Institute of Radiological Science, Chiba, Japan
| | - Ivor Benjamin
- Division of Cardiology, Internal Medicine, School of Medicine, University of Utah, Salt Lake City, Utah, United States of America
| | - Paolo Sassone-Corsi
- Center for Epigenetics and Metabolism, School of Medicine, University of California Irvine, Irvine, California, United States of America
| | - Takeaki Ozawa
- Department of Chemistry, School of Science, The University of Tokyo, Tokyo, Japan
- * E-mail: (TT); (TO)
| | - Ken Takamatsu
- Department of Physiology & Advanced Research Center for Medical Science, Toho University School of Medicine, Tokyo, Japan
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5
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Enouz S, Carrié L, Merkler D, Bevan MJ, Zehn D. Autoreactive T cells bypass negative selection and respond to self-antigen stimulation during infection. ACTA ACUST UNITED AC 2012; 209:1769-79. [PMID: 22987800 PMCID: PMC3457731 DOI: 10.1084/jem.20120905] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Autoimmunity occurs because central and peripheral tolerance mechanisms fail to tolerize T cells with weak self-reactivity to tissue-restricted antigen. Central and peripheral tolerance prevent autoimmunity by deleting the most aggressive CD8+ T cells but they spare cells that react weakly to tissue-restricted antigen (TRA). To reveal the functional characteristics of these spared cells, we generated a transgenic mouse expressing the TCR of a TRA-specific T cell that had escaped negative selection. Interestingly, the isolated TCR matches the affinity/avidity threshold for negatively selecting T cells, and when developing transgenic cells are exposed to their TRA in the thymus, only a fraction of them are eliminated but significant numbers enter the periphery. In contrast to high avidity cells, low avidity T cells persist in the antigen-positive periphery with no signs of anergy, unresponsiveness, or prior activation. Upon activation during an infection they cause autoimmunity and form memory cells. Unexpectedly, peptide ligands that are weaker in stimulating the transgenic T cells than the thymic threshold ligand also induce profound activation in the periphery. Thus, the peripheral T cell activation threshold during an infection is below that of negative selection for TRA. These results demonstrate the existence of a level of self-reactivity to TRA to which the thymus confers no protection and illustrate that organ damage can occur without genetic predisposition to autoimmunity.
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Affiliation(s)
- Sarah Enouz
- Swiss Vaccine Research Institute and Division of Immunology and Allergy, Department of Medicine, Lausanne University Hospital (CHUV), 1011 Lausanne, Switzerland
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6
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O'Sullivan JA, Zloza A, Kohlhapp FJ, Moore TV, Lacek AT, Dulin NO, Guevara-Patiño JA. Priming with very low-affinity peptide ligands gives rise to CD8(+) T-cell effectors with enhanced function but with greater susceptibility to transforming growth factor (TGF)β-mediated suppression. Cancer Immunol Immunother 2011; 60:1543-51. [PMID: 21681376 DOI: 10.1007/s00262-011-1043-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Accepted: 05/19/2011] [Indexed: 12/31/2022]
Abstract
While the effects of TCR affinity and TGFβ on CD8(+) T-cell function have been studied individually, the manner in which TCR affinity dictates susceptibility to TGFβ-mediated suppression remains unknown. To address this issue, we utilized OVA altered peptide ligands (APLs) of different affinities in the OT-I model. We demonstrate that while decreased TCR ligand affinity initially results in weakened responses, such interactions prime the resultant effector cells to respond more strongly to cognate antigen upon secondary exposure. Despite this, responses by CD8(+) T cells primed with lower-affinity TCR ligands are more effectively regulated by TGFβ. Susceptibility to TGFβ-mediated suppression is associated with downregulation of RGS3, a recently recognized negative regulator of TGFβ signaling, but not expression of TGFβ receptors I/II. These results suggest a novel tolerance mechanism whereby CD8(+) T cells are discriminately regulated by TGFβ according to the affinity of the ligand on which they were initially primed. In addition, because of the major role played by TGFβ in tumor-induced immune suppression, these results identify the affinity of the priming ligand as a primary concern in CD8(+) T-cell-mediated cancer immunotherapeutic strategies.
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Affiliation(s)
- Jeremy A O'Sullivan
- Department of Surgery, Committee on Immunology, The University of Chicago, Surgery Brain Research Building, IL 60637, USA
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7
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TCR affinity for self-ligands influences the development and function of encephalitogenic T cells. PLoS One 2011; 6:e17702. [PMID: 21437282 PMCID: PMC3060088 DOI: 10.1371/journal.pone.0017702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 02/08/2011] [Indexed: 11/25/2022] Open
Abstract
The specificity and affinity of self-reactive T cells is likely to impact the development of autoimmune-disease causing T cells in the thymus as well as their function in the periphery. We identified a naturally occurring, low affinity variant of an MBP Ac1-11/I-Au specific TCR that is known to induce EAE. Thymocytes in mice carrying the transgenes for this low affinity TCR were poorly positively selected, as compared to their high affinity TCR expressing counterparts. Nonetheless, CD4 T cells bearing the low affinity TCR accumulated in the periphery of the mice. Unlike mice expressing the high affinity TCR, these mice very rarely developed disease. However, if endogenous TCR expression was eliminated by breeding to RAG1 deficient mice, 100% of the mice carrying either the high or the low affinity versions of the TCR developed EAE. Intriguingly, while the incidence of EAE increased, the age of onset of disease in both mice was identical. These data suggest disease onset occurs during a short window of mouse development.
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Abstract
The thymus serves as the central organ of immunologic self-nonself discrimination. Thymocytes undergo both positive and negative selection, resulting in T cells with a broad range of reactivity to foreign antigens but with a lack of reactivity to self-antigens. The thymus is also the source of a subset of regulatory T cells that inhibit autoreactivity of T-cell clones that may escape negative selection. As a result of these functions, the thymus has been shown to be essential for the induction of tolerance in many rodent and large animal models. Proper donor antigen presentation in the thymus after bone marrow, dendritic cell, or solid organ transplantation has been shown to induce tolerance to allografts. The molecular mechanisms of positive and negative selection and regulatory T-cell development must be understood if a tolerance-inducing therapeutic intervention is to be designed effectively. In this brief and selective review, we present some of the known information on T-cell development and on the role of the thymus in experimental models of transplant tolerance. We also cite some clinical attempts to induce tolerance to allografts using pharmacologic or biologic interventions.
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Papapetrou EP, Kovalovsky D, Beloeil L, Sant'angelo D, Sadelain M. Harnessing endogenous miR-181a to segregate transgenic antigen receptor expression in developing versus post-thymic T cells in murine hematopoietic chimeras. J Clin Invest 2008; 119:157-68. [PMID: 19033646 DOI: 10.1172/jci37216] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Accepted: 10/15/2008] [Indexed: 12/19/2022] Open
Abstract
MicroRNAs (miRNAs) are small, noncoding RNAs that regulate gene expression by targeting complementary sequences, referred to as miRNA recognition elements (MREs), typically located in the 3' untranslated region of mRNAs. miR-181a is highly expressed in developing thymocytes and markedly downregulated in post-thymic T cells. We investigated whether endogenous miR-181a can be harnessed to segregate expression of chimeric antigen receptors (CARs) and TCRs between developing and mature T cells. Lentiviral-encoded antigen receptors were tagged with a miR-181a-specific MRE and transduced into mouse BM cells that were used to generate hematopoietic chimeras. Expression of a CAR specific for human CD19 (hCD19) was selectively suppressed in late double-negative and double-positive thymocytes, coinciding with the peak in endogenous miR-181a expression. Receptor expression was fully restored in post-thymic resting and activated T cells, affording protection against a subsequent challenge with hCD19+ tumors. Hematopoietic mouse chimeras engrafted with a conalbumin-specific TCR prone to thymic clonal deletion acquired peptide-specific T cell responsiveness only when the vector-encoded TCR transcript was similarly engineered to be subject to regulation by miR-181a. These results demonstrate the potential of miRNA-regulated transgene expression in stem cell-based therapies, including cancer immunotherapy.
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Affiliation(s)
- Eirini P Papapetrou
- Center for Cell Engineering, Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center (MSKCC), New York, NY 10065, USA
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10
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Fallas JL, Yi W, Draghi NA, O'Rourke HM, Denzin LK. Expression Patterns of H2-O in Mouse B Cells and Dendritic Cells Correlate with Cell Function. THE JOURNAL OF IMMUNOLOGY 2007; 178:1488-97. [PMID: 17237397 DOI: 10.4049/jimmunol.178.3.1488] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In the endosomes of APCs, the MHC class II-like molecule H2-M catalyzes the exchange of class II-associated invariant chain peptides (CLIP) for antigenic peptides. H2-O is another class II-like molecule that modulates the peptide exchange activity of H2-M. Although the expression pattern of H2-O in mice has not been fully evaluated, H2-O is expressed by thymic epithelial cells, B cells, and dendritic cells (DCs). In this study, we investigated H2-O, H2-M, and I-A(b)-CLIP expression patterns in B cell subsets during B cell development and activation. H2-O was first detected in the transitional 1 B cell subset and high levels were maintained in marginal zone and follicular B cells. H2-O levels were down-regulated specifically in germinal center B cells. Unexpectedly, we found that mouse B cells may have a pool of H2-O that is not associated with H2-M. Additionally, we further evaluate H2-O and H2-M interactions in mouse DCs, as well as H2-O expression in bone marrow-derived DCs. We also evaluated H2-O, H2-M, I-A(b), and I-A(b)-CLIP expression in splenic DC subsets, in which H2-O expression levels varied among the splenic DC subsets. Although it has previously been shown that H2-O modifies the peptide repertoire, H2-O expression did not alter DC presentation of a number of endogenous and exogenous Ags. Our further characterization of H2-O expression in DCs, as well as the identification of a potential free pool of H2-O in mouse splenic B cells, suggest that H2-O may have a yet to be elucidated role in immune responses.
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Affiliation(s)
- Jennifer L Fallas
- Cell Biology and Genetics Program, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10021, USA
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11
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Zehn D, Bevan MJ. T cells with low avidity for a tissue-restricted antigen routinely evade central and peripheral tolerance and cause autoimmunity. Immunity 2006; 25:261-70. [PMID: 16879996 PMCID: PMC2774714 DOI: 10.1016/j.immuni.2006.06.009] [Citation(s) in RCA: 214] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Revised: 06/12/2006] [Accepted: 06/15/2006] [Indexed: 10/24/2022]
Abstract
T cells causing autoimmunity must escape tolerance. We observed that CD8(+) T cells with high avidity for an antigen expressed in the pancreas, kidney, and thymic medulla were efficiently removed from a polyclonal repertoire by central and peripheral tolerance mechanisms. However, both mechanisms spared low-avidity T cells from elimination. Neither the introduction of activated, self-antigen-specific CD4(+) helper T cells nor a global inflammatory stimulus were sufficient to activate the low-avidity CD8(+) T cells and did not break tolerance. In contrast, challenge with a recombinant bacterium expressing the self antigen primed the low-avidity T cells, and the animals rapidly developed autoimmune diabetes. We suggest that whereas thymic and peripheral tolerance mechanisms remove cells that can be primed by endogenous amounts of self antigen, they do not guard against tissue destruction by low-avidity effector T cells, which have been primed by higher amounts of self antigen or by crossreactive antigens.
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Affiliation(s)
- Dietmar Zehn
- Department of Immunology, Howard Hughes Medical Institute, University of Washington Seattle, Washington 98195
| | - Michael J. Bevan
- Department of Immunology, Howard Hughes Medical Institute, University of Washington Seattle, Washington 98195
- Correspondence:
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12
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Hogquist KA, Baldwin TA, Jameson SC. Central tolerance: learning self-control in the thymus. Nat Rev Immunol 2005; 5:772-82. [PMID: 16200080 DOI: 10.1038/nri1707] [Citation(s) in RCA: 430] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In the past few years, there has been a flurry of discoveries and advancements in our understanding of how the thymus prepares T cells to exist at peace in normal healthy tissue: that is, to be self-tolerant. In the thymus, one of the main mechanisms of T-cell central tolerance is clonal deletion, although the selection of regulatory T cells is also important and is gaining enormous interest. In this Review, we discuss the emerging consensus about which models of clonal deletion are most physiological, and we review recent data that define the molecular mechanisms of central tolerance.
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Affiliation(s)
- Kristin A Hogquist
- Center for Immunology, Department of Laboratory Medicine and Pathology, University of Minnesota, 312 Church Street South East, Minneapolis, Minnesota 55455, USA.
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13
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Fallas JL, Tobin HM, Lou O, Guo D, Sant'Angelo DB, Denzin LK. Ectopic expression of HLA-DO in mouse dendritic cells diminishes MHC class II antigen presentation. THE JOURNAL OF IMMUNOLOGY 2004; 173:1549-60. [PMID: 15265882 DOI: 10.4049/jimmunol.173.3.1549] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The MHC class II-like molecule HLA-DM (DM) (H-2M in mice) catalyzes the exchange of CLIP for antigenic peptides in the endosomes of APCs. HLA-DO (DO) (H-2O in mice) is another class II-like molecule that is expressed in B cells, but not in other APCs. Studies have shown that DO impairs or modifies the peptide exchange activity of DM. To further evaluate the role of DO in Ag processing and presentation, we generated transgenic mice that expressed the human HLA-DOA and HLA-DOB genes under the control of a dendritic cell (DC)-specific promoter. Our analyses of DCs from these mice showed that as DO levels increased, cell surface levels of A(b)-CLIP also increased while class II-peptide levels decreased. The presentation of some, but not all, exogenous Ags to T cells or T hybridomas was significantly inhibited by DO. Surprisingly, H-2M accumulated in DO-expressing DCs and B cells, suggesting that H-2O/DO prolongs the half-life of H-2M. Overall, our studies showed that DO expression impaired H-2M function, resulting in Ag-specific down-modulation of class II Ag processing and presentation.
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Affiliation(s)
- Jennifer L Fallas
- Cell Biology and Genetics Program, Weill Graduate School of Medical Sciences, Cornell University, New York, NY 10021, USA
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14
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Mayerova D, Hogquist KA. Central tolerance to self-antigen expressed by cortical epithelial cells. THE JOURNAL OF IMMUNOLOGY 2004; 172:851-6. [PMID: 14707055 DOI: 10.4049/jimmunol.172.2.851] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The exposure of developing thymocytes to high-affinity self-Ag results in T cell tolerance. A predominant mechanism for this is clonal deletion; though receptor editing, anergy induction, and positive selection of regulatory T cells have also been described. It is unclear what signals are involved in determining different tolerance mechanisms. In particular, OT-I mice displayed receptor editing when the high-affinity self-Ag was expressed in cortical epithelial cells (cEC) using the human keratin 14 promoter. To test the hypothesis that receptor editing is a consequence of a unique instruction given by cEC presenting self-Ag, we created mice expressing the 2C and HY ligands under control of the keratin 14 promoter. Alternatively, we studied the fate of developing T cells in OT-I mice where Ag was presented by all thymic APC. Surprisingly, we found that the tolerance mechanism was not influenced by the APC subset involved in presentation. Clonal deletion was observed in 2C and HY models even when Ag was presented only by cEC; and receptor editing was observed in OT-I mice even when Ag was presented by all thymic APC. These results suggest that different TCRs show intrinsic differences in thymic tolerance mechanism.
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Affiliation(s)
- Dita Mayerova
- Center for Immunology, Department of Laboratory Medicine and Pathology, University of Minnesota, 312 Church Street SE, Minneapolis, MN 55455, USA
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15
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Nakken B, Davis KE, Pan ZJ, Bachmann M, Farris AD. T-helper cell tolerance to ubiquitous nuclear antigens. Scand J Immunol 2003; 58:478-92. [PMID: 14629620 PMCID: PMC2579760 DOI: 10.1046/j.1365-3083.2003.01323.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Systemic autoimmune diseases are characterized by the development of antinuclear autoantibodies. In order to understand the immunologic events leading to the development of such antibodies, knowledge of mechanisms of immune tolerance to nuclear antigens is required. By utilizing adoptive T-cell transfer strategies with transgenic mouse models expressing nuclear neo-self antigens, T-cell tolerance to the lupus-related nuclear antigens human La and nRNP A has been demonstrated. These findings also indicate the existence in normal animals of autoreactive B cells continuously presenting nuclear antigen, suggesting that nuclear antigens are not sequestered from the immune system. Investigations of CD4+ T-cell tolerance to non-nuclear antigens have revealed a number of mechanisms that protect the host from autoreactivity, including autoreactive T-cell deletion, regulatory T-cell development and anergy induction. Recent studies using T-cell receptor and neo-self nuclear antigen transgenic mice are revealing the importance of such mechanisms in maintaining tolerance to nuclear antigens. Mechanisms of tolerogenic antigen presentation, identification of tolerogenic antigen source(s) and the pathways leading to loss of tolerance to nuclear antigens in systemic autoimmune disease states are currently being sought.
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Affiliation(s)
- B Nakken
- Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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Abstract
A functional immune system requires the selection of T lymphocytes expressing receptors that are major histocompatibility complex restricted but tolerant to self-antigens. This selection occurs predominantly in the thymus, where lymphocyte precursors first assemble a surface receptor. In this review we summarize the current state of the field regarding the natural ligands and molecular factors required for positive and negative selection and discuss a model for how these disparate outcomes can be signaled via the same receptor. We also discuss emerging data on the selection of regulatory T cells. Such cells require a high-affinity interaction with self-antigens, yet differentiate into regulatory cells instead of being eliminated.
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Affiliation(s)
- Timothy K Starr
- Center for Immunology and the Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis 55455, USA.
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17
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Cho HJ, Edmondson SG, Miller AD, Sellars M, Alexander ST, Somersan S, Punt JA. Cutting edge: identification of the targets of clonal deletion in an unmanipulated thymus. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:10-3. [PMID: 12496375 DOI: 10.4049/jimmunol.170.1.10] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Autoreactive thymocytes can be eliminated by clonal deletion during their development in the thymus. The precise developmental stage(s) at which clonal deletion occurs in a normal thymus has been difficult to assess, in large part because of the absence of a specific marker for TCR-mediated apoptosis. In this report, we reveal that Nur77 expression can be used as a specific marker of clonal deletion in an unmanipulated thymus and directly identify TCRintCD4+CD8+ and semimature CD4+CD8- thymocytes as the principal targets of deletion. These data indicate that clonal deletion normally occurs at a relatively late stage of development, as cells mature from CD4+CD8+ thymocytes to single-positive T cells.
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Affiliation(s)
- Hyung J Cho
- Department of Biology, Haverford College, Haverford, PA 19041, USA
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18
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Dao T, Blander JM, Sant'Angelo DB. Recognition of a specific self-peptide: self-MHC class II complex is critical for positive selection of thymocytes expressing the D10 TCR. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:48-54. [PMID: 12496382 DOI: 10.4049/jimmunol.170.1.48] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We examined the specificity of positive and negative selection by using transgenic mice carrying a variant of the D10 TCR. We demonstrate that a point mutation at position 51 within the CDR2alpha segment significantly reduces the avidity of this TCR for its cognate ligand, but does not impact recognition of nonself MHC class II molecules. Although structural studies have suggested that this TCR site interacts with the MHC class II beta-chain, the avidity of this TCR for its ligand and the function of the T cell can be reconstituted by a point mutation in the bound antigenic peptide. These data demonstrate that the bound peptide can indirectly alter TCR interactions by influencing MHC structure. Remarkably, reducing the avidity of this TCR for a specific antigenic peptide-MHC ligand has a dramatic impact on thymic selection. Positive selection of thymocytes expressing this TCR is nearly completely blocked, whereas negative selection on allogenic MHC class II molecules remains intact. Therefore, the recognition of self that promotes positive selection of the D10 TCR is highly peptide-specific.
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MESH Headings
- Alleles
- Animals
- Arginine/genetics
- Autoantigens/metabolism
- Cell Differentiation/immunology
- Cell Line
- Complementarity Determining Regions/genetics
- Complementarity Determining Regions/physiology
- Conalbumin/metabolism
- Down-Regulation/genetics
- Down-Regulation/immunology
- Epitopes, T-Lymphocyte/biosynthesis
- Epitopes, T-Lymphocyte/genetics
- Glycine/genetics
- Histocompatibility Antigens Class II/genetics
- Histocompatibility Antigens Class II/metabolism
- Histocompatibility Antigens Class II/physiology
- Leucine/genetics
- Lymphocyte Count
- Mice
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Peptides/immunology
- Peptides/metabolism
- Point Mutation
- Receptors, Antigen, T-Cell, alpha-beta/antagonists & inhibitors
- Receptors, Antigen, T-Cell, alpha-beta/biosynthesis
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Serine/genetics
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Thymus Gland/cytology
- Thymus Gland/immunology
- Thymus Gland/metabolism
- Transgenes/immunology
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Affiliation(s)
- Tao Dao
- Laboratory of T Cell Immunobiology, Immunology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
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19
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Mommaas B, Kamp J, Drijfhout JW, Beekman N, Ossendorp F, Van Veelen P, Den Haan J, Goulmy E, Mutis T. Identification of a novel HLA-B60-restricted T cell epitope of the minor histocompatibility antigen HA-1 locus. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:3131-6. [PMID: 12218130 DOI: 10.4049/jimmunol.169.6.3131] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The polymorphic minor histocompatibility Ag HA-1 locus encodes two peptides, HA-1(H) and HA-1(R), with a single amino acid difference. Whereas the immunogenicity of the HA-1(R) allele has not yet been shown, the nonameric HA-1(H) peptide induces HLA-A2-restricted cytotoxic T cells in vivo and in vitro. It is not known whether the mHag HA-1(H) or HA-1(R) associates with other HLA class I molecules. Therefore, the polymorphic regions of both HA-1 alleles were analyzed to identify HLA class I binding peptides that are properly processed by proteasomal degradation. Peptide binding analyses were performed for all nonameric HA-1(H/R) peptides for binding to nine HLA class I molecules with >10% prevalence in the Caucasian population and for seven nonameric/decameric HA-1(H/R) peptides predicted to bind to HLA-A3, -B14, and -B60. Only the nonameric KECVL(H)/(R)DDL and decameric KECVL(H)/(R)DDLL peptides showed strong and stable binding to HLA-B60. In vitro digestion of 29-aa-long HA-1 peptides by purified 20S proteasomes revealed proper cleavage at the COOH termini of both HLA-B60 binding HA-1(H) and HA-1(R) peptides. In subsequent analyses, dendritic cells pulsed with the nonameric HA-1(R) peptide did not induce CTLs that recognize the natural HLA-B60/HA-1(R) ligand. In contrast, dendritic cells pulsed with the nonameric HA-1(H) peptide induced IFN-gamma-secreting T cells specific for the natural HLA-B60/HA-1(H) ligand in three HLA-B60(+) HA-1(RR) individuals, demonstrating the immunogenicity of the HLA-B60/HA-1(H) ligand. In conclusion, this study shows a novel HLA-B60-restricted T cell epitope of the minor histocompatibility Ag HA-1 locus.
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Affiliation(s)
- Bregje Mommaas
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands
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