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Antov A, Yang L, Vig M, Baltimore D, Van Parijs L. Essential role for STAT5 signaling in CD25+CD4+ regulatory T cell homeostasis and the maintenance of self-tolerance. THE JOURNAL OF IMMUNOLOGY 2004; 171:3435-41. [PMID: 14500638 DOI: 10.4049/jimmunol.171.7.3435] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A population of CD25(+)CD4(+) regulatory T cells (T regs) functions to maintain immunological self tolerance by inhibiting autoreactive T cell responses. CD25(+)CD4(+) T regs are present in low, but steady, numbers in the peripheral lymphoid tissues of healthy mice. Recent studies have shown that IL-2 is an essential growth factor for these cells. How this cytokine functions to regulate CD25(+)CD4(+) T reg homeostasis and prevent autoimmune disease remains unknown. In conventional CD4(+) T cells, IL-2 triggers signaling pathways that promote proliferation and survival by activating the STAT5 transcription factor and by increasing the expression of the antiapoptotic protein, Bcl-2. We show here that bcl-2 deficiency does not affect CD25(+)CD4(+) T reg homeostasis, and that ectopic expression of this molecule fails to rescue CD25(+)CD4(+) T reg numbers or to prevent the development of autoimmunity in IL-2-deficient mice. Furthermore, transient activation of STAT5 is sufficient to increase CD25(+)CD4(+) T reg numbers in IL-2-deficient mice. Our study uncovers an essential role for STAT5 in maintaining CD25(+)CD4(+) T reg homeostasis and self-tolerance.
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Affiliation(s)
- Andrey Antov
- Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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102
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Tsaknaridis L, Spencer L, Culbertson N, Hicks K, LaTocha D, Chou YK, Whitham RH, Bakke A, Jones RE, Offner H, Bourdette DN, Vandenbark AA. Functional assay for human CD4+CD25+ Treg cells reveals an age-dependent loss of suppressive activity. J Neurosci Res 2003; 74:296-308. [PMID: 14515359 DOI: 10.1002/jnr.10766] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
CD4+CD25+ regulatory T cells (Treg cells) prevent T cell-mediated autoimmune diseases in rodents. To develop a functional Treg assay for human blood cells, we used FACS- or bead-sorted CD4+CD25+ T cells from healthy donors to inhibit anti-CD3/CD28 activation of CD4+CD25- indicator T cells. The data clearly demonstrated classical Treg suppression of CD4+CD25- indicator cells by both CD4+CD25(+high) and CD4+CD25(+low) T cells obtained by FACS or magnetic bead sorting. Suppressive activity was found in either CD45RO- (naive) or CD45RO+ (memory) subpopulations, was independent of the TCR signal strength, required cell-cell contact, and was reversible by interleukin-2 (IL-2). Of general interest is that a wider sampling of 27 healthy donors revealed an age- but not gender-dependent loss of suppressive activity in the CD4+CD25+ population. The presence or absence of suppressive activity in CD4+CD25+ T cells from a given donor could be demonstrated consistently over time, and lack of suppression was not due to method of sorting, strength of signal, or sensitivity of indicator cells. Phenotypic markers did not differ on CD4+CD25+ T cells tested ex vivo from suppressive vs. nonsuppressive donors, although, upon activation in vitro, suppressive CD4+CD25+ T cells had significantly higher expression of both CTLA-4 and GITR than CD4+CD25- T cells from the same donors. Moreover, antibody neutralization of CTLA-4, GITR, IL-10, or IL-17 completely reversed Treg-induced suppression. Our results are highly consistent with those reported for murine Treg cells and are the first to demonstrate that suppressive activity of human CD4+CD25+ T cells declines with age.
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Affiliation(s)
- Laura Tsaknaridis
- Neuroimmunology Research and Tykeson MS Research Laboratory, Veterans Affairs Medical Center and Oregon Health and Science University, Portland, Oregon 97239, USA
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103
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Fisson S, Darrasse-Jèze G, Litvinova E, Septier F, Klatzmann D, Liblau R, Salomon BL. Continuous activation of autoreactive CD4+ CD25+ regulatory T cells in the steady state. J Exp Med 2003; 198:737-46. [PMID: 12939344 PMCID: PMC2194185 DOI: 10.1084/jem.20030686] [Citation(s) in RCA: 408] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Despite a growing interest in CD4+ CD25+ regulatory T cells (Treg) that play a major role in self-tolerance and immunoregulation, fundamental parameters of the biology and homeostasis of these cells are poorly known. Here, we show that this population is composed of two Treg subsets that have distinct phenotypes and homeostasis in normal unmanipulated mice. In the steady state, some Treg remain quiescent and have a long lifespan, in the order of months, whereas the other Treg are dividing extensively and express multiple activation markers. After adoptive transfer, tissue-specific Treg rapidly divide and expand preferentially in lymph nodes draining their target self-antigens. These results reveal the existence of a cycling Treg subset composed of autoreactive Treg that are continuously activated by tissue self-antigens.
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Affiliation(s)
- Sylvain Fisson
- CNRS UMR 7087, Batiment CERVI, Hôpital de la Pitié-Salpêtrière, 83 Boulevard de l'Hôpital, 75013 Paris, France
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104
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Leitner WW, Thalhamer J. DNA vaccines for non-infectious diseases: new treatments for tumour and allergy. Expert Opin Biol Ther 2003; 3:627-38. [PMID: 12831367 DOI: 10.1517/14712598.3.4.627] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The last decade of DNA vaccine research was characterised by a pioneer spirit and enormous enthusiasm, with a large number of publications demonstrating the usefulness of this approach. Unfortunately, DNA vaccines have not necessarily met the high clinical expectations and a number of complications need to be overcome. In the case of cancer and allergy, the requirements for achieving the objectives are very different. Vaccines against allergies need to suppress or alter an unwanted immune response, while a cancer DNA vaccine has to overcome tolerance and/or immune suppression and initiate a powerful immune response. This review addresses currently used general optimisation strategies for DNA vaccines such as modification of immunisation regimens, improving the delivery systems and using molecular adjuvants. In addition, cancer-specific approaches, such as the stimulation of innate and adaptive immunity with replicase-based DNA vaccines, and targeting non-tumour-associated antigens (TAAs) are discussed. Specifically for the optimisation of DNA vaccination against allergies, procedures such as allergen gene recoding, T helper (Th)1 modulation, and the creation of safe DNA vaccines by gene fragmentation, ubiquitination or using artificial hypoallergens are being analysed. These strategies, individually or in combination, hold the potential of making DNA vaccines useful for application in the clinic.
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Affiliation(s)
- Wolfgang W Leitner
- Immunology Group, Institute of Chemistry and Biochemistry, University of Salzburg, Salzburg, Austria
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105
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Taams L, Vukmanovic-Stejic M, Salmon M, Akbar A. Immune regulation by CD4+CD25+ regulatory T cells: implications for transplantation tolerance. Transpl Immunol 2003; 11:277-85. [PMID: 12967781 DOI: 10.1016/s0966-3274(03)00047-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In transplantation research, the achievement of life-long tolerance for the graft without the need for immunosuppressive drugs, is a major goal. In the immune system various mechanisms are in place that help to prevent unwanted immunity. These mechanisms of peripheral tolerance include deletion, anergy, ignorance and suppression. In the last decade it has been demonstrated convincingly that a naturally occurring subset of CD4+ T cells, the so-called CD4+CD25+ regulatory T cells, play a key role in the suppression/regulation of immune responses. These cells have been shown to exist in mice, rats and humans, and can be found in thymus, peripheral blood, lymphoid organs and at sites of inflammation. CD4+CD25+ regulatory T cells can down-regulate the immune response by affecting T cell responses, antibody production, cytokine secretion and antigen-presenting cells. CD4+CD25+ regulatory T cells are generated in the thymus, but importantly recent evidence suggests that they can also be generated in the periphery. This latter finding is of particular importance for transplantation immunology, since it suggests that specific manipulation or induction of these cells is achievable in vivo. Here we review the recent developments on the CD4+CD25+ regulatory T cells and we discuss the potential use of these cells in transplantation immunology.
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Affiliation(s)
- Leonie Taams
- Infection and Immunity Research Group, Franklin-Wilkins Building, 150 Stamford Street, King's College London, London SE1 9NN, UK
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106
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Game DS, Hernandez-Fuentes MP, Chaudhry AN, Lechler RI. CD4+CD25+ regulatory T cells do not significantly contribute to direct pathway hyporesponsiveness in stable renal transplant patients. J Am Soc Nephrol 2003; 14:1652-61. [PMID: 12761268 DOI: 10.1097/01.asn.0000067411.03024.a9] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
CD4(+)CD25(+) regulatory T cells have been shown to regulate a variety of autoimmune and allogeneic responses in mice and humans. The role of CD4(+)CD25(+) cells in regulating alloresponses in human transplant recipients remains uncertain. Previous research has demonstrated a reduced frequency of direct pathway donor-specific T cells in renal transplant recipients when compared with the frequency of T cells reactive to an HLA-matched third party. A number of mechanisms have been proposed to account for this finding; the purpose of this study was to determine whether CD4(+)CD25(+) cells play a significant role. Twelve stable renal transplant patients were investigated using limiting dilution assay (LDA) and ELISPOT for interferon-gamma to determine the effect of depleting CD4(+)CD25(+) cells on the direct pathway alloresponse. The percentage of CD4(+)CD25(+) cells in the peripheral blood of the study patients was equivalent to that of healthy controls. Furthermore, in no case did depletion of CD4(+)CD25(+) cells significantly increase the frequency of donor-specific T cells detected by LDA. This was also found with ELISPOT in all except one patient, in whom depletion revealed an increased frequency of alloreactive T cell to both donor and third party. Finally, kinetic analysis of the LDA data did not indicate regulation against donor when compared with third party. It is concluded that the action of CD4(+)CD25(+) regulatory cells is not the main mechanism of donor-specific hyporesponsiveness in the direct pathway of allorecognition.
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Affiliation(s)
- David S Game
- Department of Immunology, Imperial College Faculty of Medicine, Hammersmith Hospital, London, UK
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107
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Abstract
Interleukin-10 (IL-10) is a cytokine that has been tested in different clinical trials based on its ability to down regulate T helper 1-type responses, namely IFN-gamma secretion and activation of monocytes/macrophages. There is also evidence in different animal models, that IL-10 could be useful in controlling Th2-mediated inflammatory processes. However, IL-10 also displays immunostimulatory properties especially on B cells and activated CD8(+)T cells. These seemingly divergent effects may explain the apparent lack of activity or adverse effects observed after IL-10 treatment in several animal models or clinical trials. Nevertheless, the ability of IL-10 to induce the differentiation of a subset of regulatory CD4(+)T cells (Tr1) and the importance of IL-10 for the in vivo function of regulatory T cells tends to support the view of IL-10 as a crucial cytokine in the control of immune responses. In different in vivo models, these cells were shown to inhibit Th1 and Th2-type inflammatory responses through the secretion of IL-10. These Tr1 cells may thus be used in specific cellular therapy in order to deliver IL-10 precisely at the site of inflammation.
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Affiliation(s)
- Hervé Groux
- INSERM U343 Hopital de l'Archet, Route de Saint Antoine de Ginestière, Nice 06200, France.
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108
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Abstract
The induction of tolerance is essential for the maintenance of immune homeostasis, for the prevention of autoimmune diseases, and to achieve transplantation tolerance. To induce tolerance, the immune system uses several mechanisms, including the deletion of autoreactive T cells, the induction of anergy, and active suppression of autoimmune responses. The mechanisms of thymic deletion and anergy of autoreactive T cells are well characterized, whereas active suppression by T-regulatory (Tr) cells, which has recently emerged as an essential component of the immune response to induce peripheral tolerance, is less well understood. Results from seminal studies by a number of laboratories have renewed interest in CD4+ T cells with regulatory properties. Although many aspects of the mechanisms by which these cells exert their effects have still to be elucidated, it is well established that T-regulatory cells suppress immune responses by means of cell-to-cell interactions or the production of interleukin (IL)-10, transforming growth factor (TGF)-beta, or both. Type-1 Tr (Tr1) cells are defined by their ability to produce high levels of IL-10 and TGF-beta. Tr1 cells specific for a variety of antigens arise in vivo but may also differentiate from naive CD4+ T cells in the presence of IL-10 in vitro. Tr1 cells have a low proliferative capacity. Tr1 cells suppress naive and memory T-helper type 1 or 2 responses by means of production of IL-10 and TGF-beta. Further characterization of Tr1 cells at the molecular level will define their mechanisms of action and clarify their relationship with other subsets of Tr cells. The use of Tr1 cells to identify novel targets for the development of new therapeutic agents, and as a cellular therapy to modulate peripheral tolerance, can be foreseen.
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Affiliation(s)
- Hervé Groux
- Institut National de la Sante Et de la Recherche Medicale Unite 576, Hôpital de l'Archet, route de Saint-Antoine de Ginestière, 06200 Nice, France
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109
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Morgan ME, Sutmuller RPM, Witteveen HJ, van Duivenvoorde LM, Zanelli E, Melief CJM, Snijders A, Offringa R, de Vries RRP, Toes REM. CD25+ cell depletion hastens the onset of severe disease in collagen-induced arthritis. ARTHRITIS AND RHEUMATISM 2003; 48:1452-60. [PMID: 12746920 DOI: 10.1002/art.11063] [Citation(s) in RCA: 236] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVE CD4+,CD25+ T regulatory cells may offer opportunities to intervene in the course of autoimmune disease. We wished to evaluate their potential for influencing systemic and chronic joint inflammation by investigating their involvement in collagen-induced arthritis (CIA). METHODS We depleted DBA/1 mice of CD25+ regulatory cells by injection of a depleting monoclonal antibody specific for CD25 14 days before a single immunization with type II collagen (CII) in Freund's complete adjuvant. CD4+,CD25+ T cells were adoptively transferred to some groups of mice during immunization. Mice were then scored for signs of arthritis, and blood was taken periodically to measure the amounts of CII-specific antibodies. Splenocytes of treated mice were examined in vitro to determine the effects of depletion on proliferation to CII and control antigens. RESULTS CD25+ cell-depleted DBA/1 mice had significantly more severe disease than control mice following collagen immunization. The magnified severity was also accompanied by higher antibody titers against collagen, and in vitro tests showed increased proliferation of collagen-specific T cells. Adoptively transferring CD4+,CD25+ T cells into depleted mice was shown to reverse the heightened severity. Control mice, which were depleted and immunized with the neoantigen keyhole limpet hemocyanin (KLH), had neither an increased antibody response toward KLH nor an augmented proliferative response, indicating that CD25+ cell depletion preferentially affects immunity against self antigen. CONCLUSION These results establish a link between CD4+,CD25+ regulatory cells and CIA and provide a rationale for investigating CD4+,CD25+ T regulatory cells in the treatment and prevention of arthritis.
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Affiliation(s)
- Mary E Morgan
- Leiden University Medical Center, Leiden, The Netherlands.
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110
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Setiady YY, Samy ET, Tung KSK. Maternal autoantibody triggers de novo T cell-mediated neonatal autoimmune disease. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:4656-64. [PMID: 12707344 DOI: 10.4049/jimmunol.170.9.4656] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Although human maternal autoantibodies may transfer transient manifestation of autoimmune disease to their progeny, some neonatal autoimmune diseases can progress, leading to the loss of tissue structure and function. In this study we document that murine maternal autoantibody transmitted to progeny can trigger de novo neonatal pathogenic autoreactive T cell response and T cell-mediated organ-specific autoimmune disease. Autoantibody to a zona pellucida 3 (ZP3) epitope was found to induce autoimmune ovarian disease (AOD) and premature ovarian failure in neonatal, but not adult, mice. Neonatal AOD did not occur in T cell-deficient pups, and the ovarian pathology was transferable by CD4(+) T cells from diseased donors. Interestingly, neonatal AOD occurred only in pups exposed to ZP3 autoantibody from neonatal days 1-5, but not from day 7 or day 9. The disease susceptibility neonatal time window was not related to a propensity of neonatal ovaries to autoimmune inflammation, and it was not affected by infusion of functional adult CD4(+)CD25(+) T cells. However, resistance to neonatal AOD in 9-day-old mice was abrogated by CD4(+)CD25(+) T cell depletion. Finally, neonatal AOD was blocked by Ab to IgG-FcR, and interestingly, the disease was not elicited by autoantibody to a second, independent native ZP3 B cell epitope. Therefore, a new mechanism of neonatal autoimmunity is presented in which epitope-specific autoantibody stimulates de novo autoimmune pathogenic CD4(+) T cell response.
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MESH Headings
- Administration, Oral
- Adoptive Transfer
- Aging/immunology
- Amino Acid Sequence
- Animals
- Animals, Newborn/immunology
- Autoantibodies/administration & dosage
- Autoantibodies/physiology
- Autoantigens/immunology
- Autoimmune Diseases/immunology
- Autoimmune Diseases/pathology
- Autoimmune Diseases/prevention & control
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- CD4-Positive T-Lymphocytes/transplantation
- Disease Progression
- Disease Susceptibility/immunology
- Dose-Response Relationship, Immunologic
- Egg Proteins/immunology
- Epitopes, B-Lymphocyte/administration & dosage
- Epitopes, B-Lymphocyte/immunology
- Female
- Immunity, Innate
- Immunohistochemistry
- Immunophenotyping
- Lymphocyte Depletion
- Male
- Maternal-Fetal Exchange/immunology
- Membrane Glycoproteins/immunology
- Mice
- Mice, Inbred A
- Mice, Inbred C57BL
- Milk/immunology
- Molecular Sequence Data
- Organ Specificity/immunology
- Ovarian Diseases/immunology
- Ovarian Diseases/pathology
- Ovarian Diseases/prevention & control
- Peptide Fragments/immunology
- Pregnancy
- Receptors, Cell Surface
- Receptors, IgG/physiology
- Receptors, Interleukin-2/biosynthesis
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- T-Lymphocyte Subsets/transplantation
- Zona Pellucida/immunology
- Zona Pellucida Glycoproteins
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Affiliation(s)
- Yulius Y Setiady
- Department of Pathology, University of Virginia, Charlottesville, VA 22908, USA
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111
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Caramalho I, Lopes-Carvalho T, Ostler D, Zelenay S, Haury M, Demengeot J. Regulatory T cells selectively express toll-like receptors and are activated by lipopolysaccharide. J Exp Med 2003; 197:403-11. [PMID: 12591899 PMCID: PMC2193858 DOI: 10.1084/jem.20021633] [Citation(s) in RCA: 761] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Regulatory CD4 T cells (Treg) control inflammatory reactions to commensal bacteria and opportunist pathogens. Activation of Treg functions during these processes might be mediated by host-derived proinflammatory molecules or directly by bacterial products. We tested the hypothesis that engagement of germline-encoded receptors expressed by Treg participate in the triggering of their function. We report that the subset of CD4 cells known to exert regulatory functions in vivo (CD45RB(low) CD25(+)) selectively express Toll-like receptors (TLR)-4, -5, -7, and -8. Exposure of CD4(+) CD25(+) cells to the TLR-4 ligand lipopolysaccharide (LPS) induces up-regulation of several activation markers and enhances their survival/proliferation. This proliferative response does not require antigen-presenting cells and is augmented by T cell receptor triggering and interleukin 2 stimulation. Most importantly, LPS treatment increases CD4(+) CD25(+) cell suppressor efficiency by 10-fold and reveals suppressive activity in the CD4(+) CD45RB(low) CD25(-) subset that when tested ex-vivo, scores negative. Moreover, LPS-activated Treg efficiently control naive CD4 T cell-dependent wasting disease. These findings provide the first evidence that Treg respond directly to proinflammatory bacterial products, a mechanism that likely contributes to the control of inflammatory responses.
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Affiliation(s)
- Iris Caramalho
- Instituto Gulbenkian de Ciência, 2781-901 Oeiras, Portugal
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112
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Hudrisier D, Feau S, Bonnet V, Romagnoli P, Van Meerwijk JPM. In vivo maintenance of T-lymphocyte unresponsiveness induced by thymic medullary epithelium requires antigen presentation by radioresistant cells. Immunology 2003; 108:24-31. [PMID: 12519299 PMCID: PMC1782865 DOI: 10.1046/j.1365-2567.2003.01546.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The T-cell repertoire developing in the thymus is rid of autospecific cells by the process of thymic negative selection. Recognition of major histocompatibility complex (MHC)/self-peptide complexes expressed by thymic antigen-presenting cells (APC) of bone marrow origin leads to induction of apoptotic death of autospecific thymocytes. Induction of tolerance to self-antigens not presented by thymic APC is mediated by medullary thymic epithelial cells (mTEC) which express a very wide range of proteins, e.g. inducible and tissue-specific proteins. The main type of tolerance induced by mTEC is non-deletional and the issue of how it is maintained outside the thymus is therefore of crucial interest. We have previously shown that the non-T-cell receptor (TCR) -transgenic T-cell repertoire developing in conditions in which tolerance to self-MHC/peptide ligands is exclusively induced by mTEC is tolerant to syngeneic targets in vivo but lyses such targets in vitro. Here we report that this non-deletional in vivo self-tolerance is not due to active tolerance assured by known naturally occurring regulatory or immune-modulating T lymphocytes. Importantly, we show that in vivo maintenance of this therefore probably anergic state requires continued interaction of autospecific T cells with self-MHC/peptide ligands expressed by radioresistant cells while APC are incapable of maintaining the tolerant state. Therefore, maintenance of non-deletional T-lymphocyte tolerance to the wide range of self-antigens expressed by mTEC depends on continued interaction with radioresistant cells that very probably express a much more limited repertoire of antigens. Our data may therefore have important consequences for tolerance to tissue-specific and inducible self-antigens.
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Affiliation(s)
- Denis Hudrisier
- Institut National de la Santé et de la Recherche Médicale (INSERM) Centre de Physiopathologie de Toulouse-Purpan, Institut Claude de Preval, Toulouse, France
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113
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Abstract
There has recently been an explosion of renewed interest in regulatory T cells, particularly those within the CD4(+)CD25(+) population. It is becoming increasingly apparent that these cells exist not only as naturally occurring cells that may contribute to the maintenance of self-tolerance, but they also have the potential to prevent rejection of allografts in experimental models. Such cells have now been identified in humans as well as in rodents.
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Affiliation(s)
- Mahzuz Karim
- Nuffield Department of Surgery, University of Oxford, John Radcliffe Hospital, Headington, OX3 9DU, UK.
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114
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Abstract
Autoreactive cells that escape from thymic negative selection are either anergized or counter-regulated in the peripheral lymphoid organs by regulatory T (Treg) cells. Most investigated Treg cells are CD4pos cells expressing the alpha chain of the IL-2 receptor (CD25). Absence of this particular population leads to the development of a wide range of autoimmune disorders, suggesting a critical role for CD4pos CD25pos cells in the maintenance of normal immune homeostasis. Numerous studies have aimed at unraveling the mechanisms of regulation, focusing mainly on naturally occurring Treg cells (generated in naive animals) and regulation of CD4pos autoreactive cells. In contrast, generation following antigenic priming of CD4pos CD25pos Treg cells with non-self (viral) antigen specificity and regulation of virus-activated CD4pos and CD8pos cells remain to be investigated. In this review, we describe the data collected over the past few years of intense focus on CD4pos CD25pos Treg cells and present our approach to investigate the generation of antigen-specific Treg cells during the course of an anti-viral immune response.
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Affiliation(s)
- C Asseman
- La Jolla Institute for Allergy and Immunology, 10335 Science Center Drive, San Diego, CA 92122, USA
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115
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Dieckmann D, Bruett CH, Ploettner H, Lutz MB, Schuler G. Human CD4(+)CD25(+) regulatory, contact-dependent T cells induce interleukin 10-producing, contact-independent type 1-like regulatory T cells [corrected]. J Exp Med 2002; 196:247-53. [PMID: 12119349 PMCID: PMC2193931 DOI: 10.1084/jem.20020642] [Citation(s) in RCA: 363] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
It has been recently demonstrated that regulatory CD4(+)CD25(+) CD45RO(+) T cells are present in the peripheral blood of healthy adults and exert regulatory function similar to their rodent counterparts. It remains difficult to understand how the small fraction of these T cells that regulate via direct cell-to-cell contact and not via secretion of immunosuppressive cytokines could mediate strong immune suppression. Here we show that human CD4(+)CD25(+) T cells induce long-lasting anergy and production of interleukin (IL)-10 in CD4(+)CD25(-) T cells. These anergized CD4(+)CD25(-) T cells then suppress proliferation of syngenic CD4(+) T cells via IL-10 but independent of direct cell contact, similar to the so-called type 1 regulatory T (Tr1) cells. This 'catalytic' function of CD4(+)CD25(+) T cells to induce Tr1-like cells helps to explain their central role for the maintenance of immune homeostasis.
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Affiliation(s)
- Detlef Dieckmann
- Department of Dermatology, University Hospital of Erlangen, 91052 Erlangen, Germany
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