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Abstract
Involvement of T lymphocytes in kidney transplantation is a well-developed topic; however, most of the scientific interest focused on the different type of CD4+ lymphocyte subpopulations. Few authors, instead, investigated the role of CD8+ T cells in renal transplantation and how deleterious they can be to long-term allograft survival. Recently, there has been a renewed interest in the CD8+ T cells involvement in the transplantation field with the aim to investigate the immunological mechanisms underlying the infiltration of CD8+ T cells and their biological functions in human kidney allografts. The purpose of the present review is to highlight the role of allo-reactive cytotoxic T lymphocytes (CTLs) CD8+ subset in allograft kidney recipients and their related clinical complications.
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2
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Pfeil J, Simonetti M, Lauer U, Volkmer R, von Thülen B, Durek P, Krähmer R, Leenders F, Hamann A, Hoffmann U. Tolerogenic Immunomodulation by PEGylated Antigenic Peptides. Front Immunol 2020; 11:529035. [PMID: 33162973 PMCID: PMC7581722 DOI: 10.3389/fimmu.2020.529035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 09/22/2020] [Indexed: 01/29/2023] Open
Abstract
Current treatments for autoimmune disorders rely on non-specific immunomodulatory and global immunosuppressive drugs, which show a variable degree of efficiency and are often accompanied by side effects. In contrast, strategies aiming at inducing antigen-specific tolerance promise an exclusive specificity of the immunomodulation. However, although successful in experimental models, peptide-based tolerogenic "inverse" vaccines have largely failed to show efficacy in clinical trials. Recent studies showed that repetitive T cell epitopes, coupling of peptides to autologous cells, or peptides coupled to nanoparticles can improve the tolerogenic efficacy of peptides, suggesting that size and biophysical properties of antigen constructs affect the induction of tolerance. As these materials bear hurdles with respect to preparation or regulatory aspects, we wondered whether conjugation of peptides to the well-established and clinically proven synthetic material polyethylene glycol (PEG) might also work. We here coupled the T cell epitope OVA323-339 to polyethylene glycols of different size and structure and tested the impact of these nano-sized constructs on regulatory (Treg) and effector T cells in the DO11.10 adoptive transfer mouse model. Systemic vaccination with PEGylated peptides resulted in highly increased frequencies of Foxp3+ Tregs and reduced frequencies of antigen-specific T cells producing pro-inflammatory TNF compared to vaccination with the native peptide. PEGylation was found to extend the bioavailability of the model peptide. Both tolerogenicity and bioavailability were dependent on PEG size and structure. In conclusion, PEGylation of antigenic peptides is an effective and feasible strategy to improve Treg-inducing, peptide-based vaccines with potential use for the treatment of autoimmune diseases, allergies, and transplant rejection.
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Affiliation(s)
- Jennifer Pfeil
- Experimental Rheumatology, Deutsches Rheuma-Forschungszentrum, a Leibniz Institute (DRFZ), Berlin, Germany
- Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin, Berlin, Germany
| | - Mario Simonetti
- Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin, Berlin, Germany
| | - Uta Lauer
- Experimental Rheumatology, Deutsches Rheuma-Forschungszentrum, a Leibniz Institute (DRFZ), Berlin, Germany
- Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin, Berlin, Germany
| | - Rudolf Volkmer
- Institute for Medical Immunology, Charité Universitätsmedizin, Berlin, Germany
| | | | - Pawel Durek
- Experimental Rheumatology, Deutsches Rheuma-Forschungszentrum, a Leibniz Institute (DRFZ), Berlin, Germany
| | | | | | - Alf Hamann
- Experimental Rheumatology, Deutsches Rheuma-Forschungszentrum, a Leibniz Institute (DRFZ), Berlin, Germany
- Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin, Berlin, Germany
| | - Ute Hoffmann
- Experimental Rheumatology, Deutsches Rheuma-Forschungszentrum, a Leibniz Institute (DRFZ), Berlin, Germany
- Department of Rheumatology and Clinical Immunology, Charité Universitätsmedizin, Berlin, Germany
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3
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Abstract
As a common procedure in dentistry for replacing a missing tooth, allogenic tooth transplantation has encountered many difficulties in the clinical application because of immunological rejection. It is hypothesized that immature dendritic cell injection might be a potential alternative method to avoid or alleviate immunological rejection in allogenic tooth transplantation. To test this hypothesis, a mouse model of allogenic and autogeneic tooth transplantation was to established test the immunosuppressive effect of immature dendritic cells (imDCs) derived from donor bone marrows on transplant rejection in allogenic tooth transplantation. 2 × 10(6) imDCs generated with 50 U/ml GM-CSF were injected to each recipient mouse by two ways: tail vein injection 7 days before transplantation or regional dermal injection at day 0 and day 3 after transplantation. Groups of autogeneic tooth transplantation and allogenic tooth transplantation without any treatment were set as control groups. The effects were evaluated with histopathology and immunohistochemistry. We found there was no obvious rejection in autogeneic tooth transplantation group; tail intravenous injection group showed obviously alleviated rejection while local injection group and none-treatment allogenic tooth transplantation group both showed severe rejection. Our results suggested that the rejection of allogenic tooth transplantation could be alleviated by tail vein injection of donor bone marrow-derived imDCs though it could not be completely eliminated. The clinical application of imDCs in allogenic tooth transplantation still needs further deep research.
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4
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Khalifian S, Raimondi G, Lee WA, Brandacher G. Taming inflammation by targeting cytokine signaling: new perspectives in the induction of transplantation tolerance. Immunotherapy 2015; 6:637-53. [PMID: 24896631 DOI: 10.2217/imt.14.25] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Transplantation tolerance remains an elusive goal, partly due to limitations in our understanding of the interplay between inflammatory mediators and their role in the activation and regulation of T lymphocytes. Although multiple mechanisms acting both centrally and peripherally are responsible for tolerance induction, the signaling pathways leading to activation or regulation of adaptive immunity are often complex, branched, redundant and modulated by the microenvironment's inflammatory milieu. Accumulating evidence clearly indicates that inflammatory cytokines limit the tolerogenic potential of immunomodulatory protocols by supporting priming of the immune system and counteracting regulatory mechanisms, ultimately promoting rejection. In this review, we summarize recent progress in the development of novel therapeutics to manipulate this inflammatory environment and achievements in targeted inhibition of inflammatory cytokine signaling. Ultimately, robust transplant tolerance induction will probably require a multifaceted, holistic approach that integrates the various mechanisms of tolerance induction, incorporates the dynamic alterations in costimulatory requirements of alloreactive T cells, while maintaining endogenous mechanisms of immune regulation.
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Affiliation(s)
- Saami Khalifian
- Department of Plastic and Reconstructive Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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5
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Hurford A, Day T. Immune evasion and the evolution of molecular mimicry in parasites. Evolution 2013; 67:2889-904. [PMID: 24094341 DOI: 10.1111/evo.12171] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 05/08/2013] [Indexed: 12/26/2022]
Abstract
Parasites that are molecular mimics express proteins which resemble host proteins. This resemblance facilitates immune evasion because the immune molecules with the specificity to react with the parasite also cross-react with the host's own proteins, and these lymphocytes are rare. Given this advantage, why are not most parasites molecular mimics? Here we explore potential factors that can select against molecular mimicry in parasites and thereby limit its occurrence. We consider two hypotheses: (1) molecular mimics are more likely to induce autoimmunity in their hosts, and hosts with autoimmunity generate fewer new infections (the "costly autoimmunity hypothesis"); and (2) molecular mimicry compromises protein functioning, lowering the within-host replication rate and leading to fewer new infections (the "mimicry trade-off hypothesis"). Our analysis shows that although both hypotheses may select against molecular mimicry in parasites, unique hallmarks of protein expression identify whether selection is due to the costly autoimmunity hypothesis or the mimicry trade-off hypothesis. We show that understanding the relevant selective forces is necessary to predict how different medical interventions will affect the proportion of hosts that experience the different infection types, and that if parasite evolution is ignored, interventions aimed at reducing infection-induced autoimmunity may ultimately fail.
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Affiliation(s)
- Amy Hurford
- Department of Mathematics and Statistics, Queen's University, Kingston, Ontario, Canada; Department of Biology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada; Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada.
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6
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Priyadharshini B, Greiner DL, Brehm MA. T-cell activation and transplantation tolerance. Transplant Rev (Orlando) 2012; 26:212-22. [PMID: 22074786 PMCID: PMC3294261 DOI: 10.1016/j.trre.2011.09.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 08/16/2011] [Accepted: 09/02/2011] [Indexed: 12/28/2022]
Abstract
Transplantation of allogeneic or "nonself" tissues stimulates a robust immune response leading to graft rejection, and therefore, most recipients of allogeneic organ transplants require the lifelong use of immune suppressive agents. Excellent outcomes notwithstanding, contemporary immunosuppressive medications are toxic, are often not taken by patients, and pose long-term risks of infection and malignancy. The ultimate goal in transplantation is to develop new treatments that will supplant the need for general immunosuppression. Here, we will describe the development and application of costimulation blockade to induce transplantation tolerance and discuss how the diverse array of signals that act on T cells will determine the balance between graft survival and rejection.
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Affiliation(s)
- Bhavana Priyadharshini
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Biotech 2, Worcester, MA 01605
| | - Dale L. Greiner
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Biotech 2, Worcester, MA 01605
| | - Michael A. Brehm
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Biotech 2, Worcester, MA 01605
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7
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Immunogenicity of biologically-derived therapeutics: assessment and interpretation of nonclinical safety studies. Regul Toxicol Pharmacol 2009; 54:164-82. [PMID: 19345250 DOI: 10.1016/j.yrtph.2009.03.012] [Citation(s) in RCA: 172] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 03/24/2009] [Accepted: 03/25/2009] [Indexed: 11/20/2022]
Abstract
An evaluation of potential antibody formation to biologic therapeutics during the course of nonclinical safety studies and its impact on the toxicity profile is expected under current regulatory guidance and is accepted standard practice. However, approaches for incorporating this information in the interpretation of nonclinical safety studies are not clearly established. Described here are the immunological basis of anti-drug antibody formation to biopharmaceuticals (immunogenicity) in laboratory animals, and approaches for generating and interpreting immunogenicity data from nonclinical safety studies of biotechnology-derived therapeutics to support their progression to clinical evaluation. We subscribe that immunogenicity testing strategies should be adapted to the specific needs of each therapeutic development program, and data generated from such analyses should be integrated with available clinical and anatomic pathology, pharmacokinetic, and pharmacodynamic data to properly interpret nonclinical studies.
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8
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Abstract
Tyrosine phosphorylation and dephosphorylation of proteins play a critical role for many T-cell functions. The opposing actions of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs) determine the level of tyrosine phosphorylation at any time. It is well accepted that PTKs are essential during T-cell signaling; however, the role and importance of PTPs are much less known and appreciated. Both transmembrane and cytoplasmic tyrosine phosphatases have been identified in T cells and shown to regulate T-cell responses. This review focuses on the roles of the two cytoplasmic PTPs, the Src-homology 2 domain (SH2)-containing SHP-1 and SHP-2, in T-cell signaling, development, differentiation, and function.
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Affiliation(s)
- Ulrike Lorenz
- Department of Microbiology and The Beirne Carter Center for Immunology Research, University of Virginia, Charlottesville, VA 22908-0734, USA.
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9
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Huang Y, Sui Y, Zhang X, Si S, Ge W, Hu P, Li X, Ma B. Response of T cells in vivo induced by repeated superantigen treatments at different time intervals. Acta Biochim Biophys Sin (Shanghai) 2007; 39:467-74. [PMID: 17622466 DOI: 10.1111/j.1745-7270.2007.00308.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
We have investigated the response of T cells to staphylococcal enterotoxin A (SEA) injections in vivo. We found that a single injection of SEA with an optimal dose of 10 microg increased the expression of both CD4 and CD8 significantly. There was expansion of SEA-reactive T cells in vivo after SEA re-injection and the time interval between injections strongly influenced the responsiveness of CD4+ and CD8+ T cells. Anergy of T cells was observed after three SEA treatments. The time interval between injections mainly affected the unresponsiveness of CD4+ T cells, not CD8+ T cells. Marked deletion followed by anergy of CD4+ T cells was induced at short intervals, and anergy without obvious deletion of CD4+ T cells was induced at long intervals. We also found that the anergic state was reversible in vivo. Repeated SEA stimulation led to down-regulation of interleukin (IL)-2, and high levels of IL-10. This study showed that both CD4+ and CD8+ SEA-primed T cells were responsive to SEA rechallenge in vivo, and a third injection was needed to induce the anergy of T cells.
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Affiliation(s)
- Yang Huang
- State Key Laboratory of Cancer Biology, Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
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10
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Coppage M, Belanger T, Zauderer M, Sahasrabudhe D. In vitro generation of tumor specific T cells that recognize a shared antigen of AML: molecular characterization of TCR genes. Leuk Res 2006; 31:195-202. [PMID: 16750565 DOI: 10.1016/j.leukres.2006.04.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Revised: 03/23/2006] [Accepted: 04/07/2006] [Indexed: 10/24/2022]
Abstract
The identification of immunologically relevant tumor antigens is hampered by the difficulty of generating tumor-specific cytotoxic T cells (CTL). We present data demonstrating in vitro induction of autologous acute myelogenous leukemia (AML)-specific CTL. The specific T cell receptor has been identified and cloned. The CTL demonstrated specific lysis to autologous tumor blasts, but not to autologous BLCL or the NK-sensitive target K562. The clone secreted GM-CSF, TNFa, and IFNg when stimulated with AML blasts from 3 of 11 patients or cell lines tested, but not with K562 or autologous B-LCL. These three AML samples share a single HLA Class I antigen, HLA-A24. The T cell receptor genes identified by molecular methods are Vbeta7.9-J2.3-Cbeta2 and Valpha17-J49-Calpha.
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Affiliation(s)
- Myra Coppage
- University of Rochester Department of Pathology and Laboratory Medicine, 601 Elmwood Avenue, Rochester, NY 14642, United States.
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11
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Opdenakker G, Dillen C, Fiten P, Martens E, Van Aelst I, Van den Steen PE, Nelissen I, Starckx S, Descamps FJ, Hu J, Piccard H, Van Damme J, Wormald MR, Rudd PM, Dwek RA. Remnant epitopes, autoimmunity and glycosylation. Biochim Biophys Acta Gen Subj 2006; 1760:610-5. [PMID: 16439062 DOI: 10.1016/j.bbagen.2005.12.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Revised: 12/12/2005] [Accepted: 12/12/2005] [Indexed: 10/25/2022]
Abstract
The role of extracellular proteolysis in innate and adaptive immunity and the interplay between cytokines, chemokines and proteinases are gradually becoming recognized as critical factors in autoimmune processes. Many of the involved proteinases, including those of the plasminogen activator and matrix metalloproteinase cascades, and also several cytokines and chemokines, are glycoproteins. The stability, interactions with inhibitors or receptors, and activities of these molecules are fine-controlled by glycosylation. We studied gelatinase B or matrix metalloproteinase-9 (MMP-9) as a glycosylated enzyme involved in autoimmunity. In the joints of rheumatoid arthritis patients, CXC chemokines, such as interleukin-8/CXCL8, recruit and activate neutrophils to secrete prestored neutrophil collagenase/MMP-8 and gelatinase B/MMP-9. Gelatinase B potentiates interleukin-8 at least tenfold and thus enhances neutrophil and lymphocyte influxes to the joints. When cartilage collagen type II is cleaved at a unique site by one of several collagenases (MMP-1, MMP-8 or MMP-13), it becomes a substrate of gelatinase B. Human gelatinase B cleaves the resulting two large collagen fragments into at least 33 peptides of which two have been shown to be immunodominant, i.e., to elicit activation and proliferation of autoimmune T cells. One of these two remnant epitopes contains a glycan which is important for its immunoreactivity. In addition to the role of gelatinase B as a regulator in adaptive immune processes, we have also demonstrated that it destroys interferon-beta, a typical innate immunity effector molecule and therapeutic cytokine in multiple sclerosis. Furthermore, glycosylated interferon-beta, expressed in Chinese hamster ovary cells, was more resistant to this proteolysis than recombinant interferon-beta from bacteria. These data not only prove that glycosylation of proteins is mechanistically important in the pathogenesis of autoimmune diseases, but also show that targeting of glycosylated proteinases or the use of glycosylated cytokines seems also critical for the treatment of autoimmune diseases.
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Affiliation(s)
- Ghislain Opdenakker
- Rega Institute for Medical Research, Laboratory of Immunobiology, University of Leuven, Belgium.
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12
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Zhang Z, Li S, Zhang L, Li Y, Lu Y, Wei B, Bu H. The characteristics of tolerogenic plasmacytoid dendritic cells stimulated with interleukin-3. Transplant Proc 2005; 37:7-9. [PMID: 15808528 DOI: 10.1016/j.transproceed.2004.12.266] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This study focused on whether bone marrow would differentiate tolerogenic dendritic cells (DCs) by comparing interleukin-3 (IL-3) DCs (induced by IL-3+IL-4) with GM-CSF DCs (induced by GM-CSF+IL-4, generating myeloid DCs). Mouse bone marrow progenitors were induced in vitro to differentiate into DCs by exposure to IL-3. The morphology and yields of IL-3 DCs and GM-CSF DCs were compared by scanning electron microscopy and laser scanning confocal microscopy. Immunohistochemistry and flow cytometer (FCM) were used to identify immune phenotypes. The results showed that IL-3 DCs and GM-CSF DCs both expressed the specific marker DEC-205 with about 80% and 70% purity, respectively. IL-3 DCs had similar morphology as plasma cells, but a different immune phenotype, namely, CD80(-), CD86(-), CD14(-), and MHC class II(+). IL-3 DCs remained in the costimulatory molecule-deficient state when TNF-alpha was supplemented into the culture. We therefore propose that IL-3 induces a high purity and yield of DCs from bone marrow. Since IL-3 DCs possess a tolerogenic phenotype (MHC class II(+), B7(-)), they may induce alloantigen-specific hyporesponsiveness in vitro.
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Affiliation(s)
- Z Zhang
- Key Laboratory of Transplant Engineering and Immunology, Ministry of Health, West China Hospital, Sichuan University, P.R. China
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13
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Thorsby E, Lie BA. HLA associated genetic predisposition to autoimmune diseases: Genes involved and possible mechanisms. Transpl Immunol 2005; 14:175-82. [PMID: 15982560 DOI: 10.1016/j.trim.2005.03.021] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2005] [Indexed: 01/03/2023]
Abstract
Autoimmune diseases are the result of an interplay between predisposing genes and triggering environmental factors, leading to loss of self-tolerance and an immune-mediated destruction of autologous cells and/or tissues. Genes in the HLA complex are among the strongest predisposing genetic factors. The HLA complex genes primarily involved are most often those encoding the peptide-presenting HLA class I or II molecules. A probable mechanism is preferential presentation by the disease-associated HLA molecules of peptides from autoantigens to T cells. Recent studies have shown, however, that other genes in the HLA complex also contribute. Taken together, available evidence suggests that the HLA complex harbour both disease predisposing genes which are quite specific for some autoimmune diseases (e.g. HLA-B27 for ankylosing spondylitis) and others which may be more common for several diseases. This will be briefly reviewed in the following.
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Affiliation(s)
- Erik Thorsby
- Institute of Immunology, Rikshospitalet University Hospital and University of Oslo, Rikshospitalet, Oslo, Norway.
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14
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Rodriguez-Lecompte JC, Kruth S, Gyorffy S, Wan YH, Gauldie J. Cell-based cancer gene therapy: breaking tolerance or inducing autoimmunity? Anim Health Res Rev 2005; 5:227-34. [PMID: 15984329 DOI: 10.1079/ahr200473] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
This review examines the mechanisms involved in anti-tumor immunity and how peptides present in many tumor types (tumor-associated antigens) are recognized by T cells from tumor-bearing cancer patients. Tumor-associated antigens are derived from proteins that are also expressed in normal cells. It is predicted that immune responses to such peptides will be compromised by self-tolerance or that stimulation of effective immune responses will be accompanied by autoimmunity. We also consider that the immunity induced against two autoantigens, which are highly conserved in vertebrates, involve qualitatively different mechanisms, such as the production of antibodies and cell-mediated immune responses. However, both pathways lead to tumor immunity and identical phenotypic manifestations of autoimmunity. Appropriate selection of the optimal tumor antigen is critical for the induction of an anti-tumor immune response. Thus, we stress that the methods for antigen presentation using dendritic cells play a critical role in the development of tumor vaccines, to break immune tolerance and induce a strong immune response against them. The viability and feasibility of expansion of canine dendritic cells from bone marrow and peripheral blood ex vivo for the treatment of spontaneous cancers in dogs is also discussed.
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15
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Carter JD, Calabrese GM, Naganuma M, Lorenz U. Deficiency of the Src homology region 2 domain-containing phosphatase 1 (SHP-1) causes enrichment of CD4+CD25+ regulatory T cells. THE JOURNAL OF IMMUNOLOGY 2005; 174:6627-38. [PMID: 15905501 DOI: 10.4049/jimmunol.174.11.6627] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A subpopulation of T cells, named regulatory T cells (T(reg) cells), has been shown to play a key role in tolerance and the prevention of autoimmunity. It is not known how changes in TCR signal strength during thymic T cell development affect the generation of a T(reg) population. In this study, we took two different strategies to modulate the TCR signal strength: an intrinsic approach, where signaling was enhanced by the loss of a negative regulator, and an extrinsic approach, where signaling strength was altered through variations in the concentrations of the selecting peptide. The tyrosine phosphatase Src homology region 2 domain-containing phosphatase 1 (SHP-1) is a known negative regulator of TCR-mediated signaling. motheaten mice, lacking expression of SHP-1, showed a 2- to 3-fold increase in the percentage of CD4(+)CD25(+) T(reg) cells within the CD4(+) T cells. Similarly, the percentage of T(reg) cells was heightened in fetal thymic organ cultures (FTOCs) derived from motheaten mice compared with wild-type FTOCs, thus establishing the thymic origin of these T(reg) cells. Using FTOCs derived from DO11.10 TCR transgenic mice, we demonstrated that exposure to increasing concentrations of the cognate OVA peptide favored the appearance of T(reg) cells. Our data suggest that the development of CD4(+)CD25(+) T(reg) cells is intrinsically different from non-T(reg) cells and that T(reg) cells are selectively enriched under conditions of enhanced negative selection. Our data also reveal a key role for the SHP-1-mediated regulation of TCR signal strength in influencing the ratio of T(reg) vs non-T(reg) cells.
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MESH Headings
- Animals
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- Cell Proliferation
- Coculture Techniques
- Intracellular Signaling Peptides and Proteins
- Mice
- Mice, Inbred BALB C
- Mice, Mutant Strains
- Mice, Transgenic
- Organ Culture Techniques
- Ovalbumin/immunology
- Protein Phosphatase 1
- Protein Tyrosine Phosphatase, Non-Receptor Type 6
- Protein Tyrosine Phosphatases/deficiency
- Protein Tyrosine Phosphatases/genetics
- Protein Tyrosine Phosphatases/physiology
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/physiology
- Receptors, Interleukin-2/biosynthesis
- Receptors, Interleukin-2/physiology
- Signal Transduction/genetics
- Signal Transduction/immunology
- Spleen/cytology
- Spleen/enzymology
- Spleen/immunology
- T-Lymphocytes, Regulatory/cytology
- T-Lymphocytes, Regulatory/enzymology
- T-Lymphocytes, Regulatory/immunology
- Thymus Gland/cytology
- Thymus Gland/enzymology
- Thymus Gland/immunology
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Affiliation(s)
- Jennifer D Carter
- Department of Microbiology and The Beirne Carter Center for Immunology Research, Charlottesville, VA 22908, USA
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16
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Thorsby E, Pfeffer P, Leivestad T. Role of hla molecules in the induction of alloimmune responses: clinical significance in the cyclosporine era. Transplant Proc 2004; 36:16S-21S. [PMID: 15041301 DOI: 10.1016/j.transproceed.2004.01.058] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
HLA molecules are peptide-presenting molecules for T cells. T-cell receptors (TCR) recognize antigen-derived peptides bound to HLA molecules in cell membranes, namely, peptide-HLA (pHLA) complexes. An allograft will be recognized as foreign by recipient T cells via two slightly different mechanisms--direct and indirect allorecognition. In direct allorecognition, recipient T cells directly recognize foreign pHLA complexes on donor cells, in particular on donor dendritic cells (DC). In indirect allorecognition, recipient T cells recognize foreign peptides from the graft presented by self-HLA molecules on recipient DC. Cyclosporine (CsA) inhibits some activation signals in T cells as the result of allorecognition. Notwithstanding the strong immunosuppressive effects of CsA, reducing the degree of allorecognition through HLA matching is still of clinical significance. Data from our own transplant center and results from others demonstrate that the introduction of CsA as a main immunosuppressive drug does not nullify the significant beneficial effects of HLA matching on the frequency and strength of rejection episodes as well as on graft survival after allotransplantation. In cadaveric donor transplantation we observe significant effects of matching just for a limited number of (broad) HLA-DR molecules. We conclude that one should take advantage both of the strong immunosuppressive effects of CsA and other modern immunosuppressants as well as the beneficial effects of optimal HLA matching in clinical transplantation.
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Affiliation(s)
- E Thorsby
- Institute of Immunology, Rikshospitalet University Hospital, Oslo, Norway
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17
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Fehérvári Z, Sakaguchi S. A paragon of self-tolerance: CD25+CD4+ regulatory T cells and the control of immune responses. Arthritis Res Ther 2003; 6:19-25. [PMID: 14979928 PMCID: PMC400424 DOI: 10.1186/ar1037] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2003] [Accepted: 12/03/2003] [Indexed: 01/07/2023] Open
Abstract
The interest in naturally arising regulatory T (TR) cells as a paradigm for maintaining immunological self-tolerance has undergone an explosive re-emergence in recent years. This renaissance was triggered by several key experimental observations and the identification of specific molecular markers that have enabled the isolation and experimental manipulation of these cells. Although their existence was once controversial, a large body of evidence now highlights the critical roles of TR cells in maintaining immunological self-tolerance. Furthermore, abnormality of natural TR cells can be a primary cause of autoimmune and other inflammatory diseases in humans.
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Affiliation(s)
- Zoltán Fehérvári
- Department of Experimental Pathology, Kyoto University, Kyoto, Japan.
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