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Caruso B, Moran AE. Thymic expression of immune checkpoint molecules and their implication for response to immunotherapies. Trends Cancer 2023:S2405-8033(23)00063-8. [PMID: 37173189 DOI: 10.1016/j.trecan.2023.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 04/07/2023] [Accepted: 04/14/2023] [Indexed: 05/15/2023]
Abstract
The thymus is responsible for generating a diverse T cell repertoire that is tolerant to self, but capable of responding to various immunologic insults, including cancer. Checkpoint blockade has changed the face of cancer treatment by targeting inhibitory molecules, which are known to regulate peripheral T cell responses. However, these inhibitory molecules and their ligands are expressed during T cell development in the thymus. In this review, we describe the underappreciated role of checkpoint molecule expression during the formation of the T cell repertoire and detail the importance of inhibitory molecules in regulating T cell lineage commitment. Understanding how these molecules function in the thymus may inform therapeutic strategies for better patient outcomes.
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Affiliation(s)
- Breanna Caruso
- Cell, Developmental and Cancer Biology, Oregon Health and Science University, Portland, OR, USA
| | - Amy E Moran
- Cell, Developmental and Cancer Biology, Oregon Health and Science University, Portland, OR, USA; Knight Cancer Institute, Oregon Health and Science University, Portland, OR, USA.
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2
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Sukegawa K, Shitaoka K, Hamana H, Kobayashi E, Miyahara Y, Fujii K, Tsuda K, Saeki S, Nagata T, Ozawa T, Saito S, Fujii T, Muraguchi A, Shiku H, Kishi H. Relationship between T cell receptor clonotype and PD‐1 expression of tumor‐infiltrating lymphocytes in colorectal cancer. Eur J Immunol 2020; 50:1580-1590. [DOI: 10.1002/eji.201948399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 04/15/2020] [Accepted: 05/19/2020] [Indexed: 01/04/2023]
Affiliation(s)
- Kenta Sukegawa
- Department of Immunology, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
- Department of Surgery and Science, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
| | - Kiyomi Shitaoka
- Department of Immunology, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
| | - Hiroshi Hamana
- Department of Immunology, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
| | - Eiji Kobayashi
- Department of Immunology, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
| | - Yoshihiro Miyahara
- Department of Personalized Cancer Immunotherapy Mie University Graduate School of Medicine Mie Japan
| | - Keisuke Fujii
- Department of Immuno‐Gene Therapy Mie University Graduate School of Medicine Mie Japan
| | - Kei Tsuda
- Department of Immunology, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
- Department of Obstetrics and Gynecology, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
| | - Shiori Saeki
- Department of Immunology, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
- Department of Surgery and Science, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
| | - Takuya Nagata
- Department of Surgery and Science, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
| | - Tatsuhiko Ozawa
- Department of Immunology, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
| | - Shigeru Saito
- Department of Obstetrics and Gynecology, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
| | - Tsutomu Fujii
- Department of Surgery and Science, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
| | - Atsushi Muraguchi
- Department of Immunology, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
| | - Hiroshi Shiku
- Department of Personalized Cancer Immunotherapy Mie University Graduate School of Medicine Mie Japan
| | - Hiroyuki Kishi
- Department of Immunology, Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
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3
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Neier SC, Ferrer A, Wilton KM, Smith SEP, Kelcher AMH, Pavelko KD, Canfield JM, Davis TR, Stiles RJ, Chen Z, McCluskey J, Burrows SR, Rossjohn J, Hebrink DM, Carmona EM, Limper AH, Kappes DJ, Wettstein PJ, Johnson AJ, Pease LR, Daniels MA, Neuhauser C, Gil D, Schrum AG. The early proximal αβ TCR signalosome specifies thymic selection outcome through a quantitative protein interaction network. Sci Immunol 2020; 4:4/32/eaal2201. [PMID: 30770409 DOI: 10.1126/sciimmunol.aal2201] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 01/17/2019] [Indexed: 12/18/2022]
Abstract
During αβ T cell development, T cell antigen receptor (TCR) engagement transduces biochemical signals through a protein-protein interaction (PPI) network that dictates dichotomous cell fate decisions. It remains unclear how signal specificity is communicated, instructing either positive selection to advance cell differentiation or death by negative selection. Early signal discrimination might occur by PPI signatures differing qualitatively (customized, unique PPI combinations for each signal), quantitatively (graded amounts of a single PPI series), or kinetically (speed of PPI pathway progression). Using a novel PPI network analysis, we found that early TCR-proximal signals distinguishing positive from negative selection appeared to be primarily quantitative in nature. Furthermore, the signal intensity of this PPI network was used to find an antigen dose that caused a classic negative selection ligand to induce positive selection of conventional αβ T cells, suggesting that the quantity of TCR triggering was sufficient to program selection outcome. Because previous work had suggested that positive selection might involve a qualitatively unique signal through CD3δ, we reexamined the block in positive selection observed in CD3δ0 mice. We found that CD3δ0 thymocytes were inhibited but capable of signaling positive selection, generating low numbers of MHC-dependent αβ T cells that expressed diverse TCR repertoires and participated in immune responses against infection. We conclude that the major role for CD3δ in positive selection is to quantitatively boost the signal for maximal generation of αβ T cells. Together, these data indicate that a quantitative network signaling mechanism through the early proximal TCR signalosome determines thymic selection outcome.
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Affiliation(s)
- Steven C Neier
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN, USA.,Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Alejandro Ferrer
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Katelynn M Wilton
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN, USA.,Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, MN, USA.,Medical Scientist Training Program, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Stephen E P Smith
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - April M H Kelcher
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN, USA.,Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, MN, USA.,Department of Neurology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Kevin D Pavelko
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Jenna M Canfield
- Molecular Pathogenesis and Therapeutics PhD Graduate Program, University of Missouri, Columbia, MO, USA
| | - Tessa R Davis
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Robert J Stiles
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Zhenjun Chen
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Victoria 3010, Australia
| | - James McCluskey
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Scott R Burrows
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland 4006, Australia.,School of Medicine, University of Queensland, Brisbane, Queensland 4006, Australia
| | - Jamie Rossjohn
- Infection and Immunity Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia.,Institute of Infection and Immunity, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| | - Deanne M Hebrink
- Thoracic Diseases Research Unit, Division of Pulmonary Critical Care and Internal Medicine, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Eva M Carmona
- Thoracic Diseases Research Unit, Division of Pulmonary Critical Care and Internal Medicine, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Andrew H Limper
- Thoracic Diseases Research Unit, Division of Pulmonary Critical Care and Internal Medicine, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Dietmar J Kappes
- Blood Cell Development and Cancer Keystone, Immune Cell Development and Host Defense Program, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Peter J Wettstein
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN, USA.,Department of Surgery, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Aaron J Johnson
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN, USA.,Department of Neurology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Larry R Pease
- Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Mark A Daniels
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO, USA.,Department of Surgery, School of Medicine, University of Missouri, Columbia, MO, USA
| | | | - Diana Gil
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO, USA. .,Department of Surgery, School of Medicine, University of Missouri, Columbia, MO, USA.,Department of Bioengineering, College of Engineering, University of Missouri, Columbia, MO, USA
| | - Adam G Schrum
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO, USA. .,Department of Surgery, School of Medicine, University of Missouri, Columbia, MO, USA.,Department of Bioengineering, College of Engineering, University of Missouri, Columbia, MO, USA
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4
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Kumbhari A, Kim PS, Lee PP. Optimisation of anti-cancer peptide vaccines to preferentially elicit high-avidity T cells. J Theor Biol 2020; 486:110067. [DOI: 10.1016/j.jtbi.2019.110067] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 09/24/2019] [Accepted: 11/01/2019] [Indexed: 10/25/2022]
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5
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Bekeschus S, Clemen R, Metelmann HR. Potentiating anti-tumor immunity with physical plasma. CLINICAL PLASMA MEDICINE 2018. [DOI: 10.1016/j.cpme.2018.10.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Takada K, Kondo K, Takahama Y. Generation of Peptides That Promote Positive Selection in the Thymus. THE JOURNAL OF IMMUNOLOGY 2017; 198:2215-2222. [PMID: 28264997 DOI: 10.4049/jimmunol.1601862] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 11/29/2016] [Indexed: 11/19/2022]
Abstract
To establish an immunocompetent TCR repertoire that is useful yet harmless to the body, a de novo thymocyte repertoire generated through the rearrangement of genes that encode TCR is shaped in the thymus through positive and negative selection. The affinity between TCRs and self-peptides associated with MHC molecules determines the fate of developing thymocytes. Low-affinity TCR engagement with self-peptide-MHC complexes mediates positive selection, a process that primarily occurs in the thymic cortex. Massive efforts exerted by many laboratories have led to the characterization of peptides that can induce positive selection. Moreover, it is now evident that protein degradation machineries unique to cortical thymic epithelial cells play a crucial role in the production of MHC-associated self-peptides for inducing positive selection. This review summarizes current knowledge on positive selection-inducing self-peptides and Ag processing machineries in cortical thymic epithelial cells. Recent studies on the role of positive selection in the functional tuning of T cells are also discussed.
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Affiliation(s)
- Kensuke Takada
- Division of Experimental Immunology, Institute of Advanced Medical Sciences, University of Tokushima, Tokushima 770-8503, Japan
| | - Kenta Kondo
- Division of Experimental Immunology, Institute of Advanced Medical Sciences, University of Tokushima, Tokushima 770-8503, Japan
| | - Yousuke Takahama
- Division of Experimental Immunology, Institute of Advanced Medical Sciences, University of Tokushima, Tokushima 770-8503, Japan
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7
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Seledtsov VI, Goncharov AG, Seledtsova GV. Clinically feasible approaches to potentiating cancer cell-based immunotherapies. Hum Vaccin Immunother 2016; 11:851-69. [PMID: 25933181 DOI: 10.1080/21645515.2015.1009814] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The immune system exerts both tumor-destructive and tumor-protective functions. Mature dendritic cells (DCs), classically activated macrophages (M1), granulocytes, B lymphocytes, aβ and ɣδ T lymphocytes, natural killer T (NKT) cells, and natural killer (NK) cells may be implicated in antitumor immunoprotection. Conversely, tolerogenic DCs, alternatively activated macrophages (M2), myeloid-derived suppressor cells (MDSCs), and regulatory T (Tregs) and B cells (Bregs) are capable of suppressing antitumor immune responses. Anti-cancer vaccination is a useful strategy to elicit antitumor immune responses, while overcoming immunosuppressive mechanisms. Whole tumor cells or lysates derived thereof hold more promise as cancer vaccines than individual tumor-associated antigens (TAAs), because vaccinal cells can elicit immune responses to multiple TAAs. Cancer cell-based vaccines can be autologous, allogeneic or xenogeneic. Clinical use of xenogeneic vaccines is advantageous in that they can be most effective in breaking the preexisting immune tolerance to TAAs. To potentiate immunotherapy, vaccinations can be combined with other modalities that target different immune pathways. These modalities include 1) genetic or chemical modification of cell-based vaccines; 2) cross-priming TAAs to T cells by engaging dendritic cells; 3) T-cell adoptive therapy; 4) stimulation of cytotoxic inflammation by non-specific immunomodulators, toll-like receptor (TLR) agonists, cytokines, chemokines or hormones; 5) reduction of immunosuppression and/or stimulation of antitumor effector cells using antibodies, small molecules; and 6) various cytoreductive modalities. The authors envisage that combined immunotherapeutic strategies will allow for substantial improvements in clinical outcomes in the near future.
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Key Words
- ADCC, antibody-dependent cell cytotoxicity
- APC, antigen-presenting cell
- Ab, antibodies
- BCG, Bacillus Calmette-Guérin
- Breg, regulatory B cell
- CAR, chimeric antigen receptor
- COX, cyclooxygenase
- CTA, cancer/testis antigen
- CTL, cytotoxic T lymphocyte
- CTLA-4, cytotoxic T lymphocyte antigen-4
- DC, dendritic cell
- DTH, delayed-type hypersensitivity
- GITR, glucocorticoid-induced tumor necrosis factor receptor
- GM-CSF, granulocyte-macrophage colony stimulating factor
- HIFU, high-intensity focused ultrasound
- IDO, indoleamine-2, 3-dioxygenase
- IFN, interferon
- IL, interleukin
- LAK, lymphokine-activated killer
- M, macrophage
- M1, classically activated macrophage
- M2, alternatively activated macrophage, MDSC, myeloid-derived suppressor cell
- MHC, major histocompatibility complex
- NK, natural killer (cell)
- PD-1, programmed death-1
- PGE2, prostaglandin E2
- RFA, radiofrequency ablation
- RNS, reactive nitrogen species
- ROS
- TAA, tumor-associated antigen
- TGF, transforming growth factor
- TLR, toll-like receptor
- TNF, tumor necrosis factor
- Th, T-helper cell
- Treg, regulatory T cell
- VEGF, vascular endothelial growth factor
- antitumor immunoprotection
- cancer cell-based vaccines
- combined immunotherapy
- immunosuppression
- reactive oxygen species
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Affiliation(s)
- V I Seledtsov
- a lmmanuel Kant Baltic Federal University ; Kaliningrad , Russia
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8
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Lymphocyte repertoire selection and intracellular self/non-self-discrimination: historical overview. Immunol Cell Biol 2014; 93:297-304. [PMID: 25385066 DOI: 10.1038/icb.2014.96] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/19/2014] [Accepted: 10/15/2014] [Indexed: 02/07/2023]
Abstract
Immunological self/non-self-discrimination is conventionally seen as an extracellular event, involving interactions been receptors on T cells pre-educated to discriminate and peptides bound to major histocompatibility complex proteins (pMHCs). Mechanisms by which non-self peptides might first be sorted intracellularly to distinguish them from the vast excess of self-peptides have long been called for. Recent demonstrations of endogenous peptide-specific clustering of pMHCs on membrane rafts are indicative of intracellular enrichment before surface display. The clustering could follow the specific aggregation of a foreign protein that exceeded its solubility limit in the crowded intracellular environment. Predominantly entropy-driven, this homoaggregation would colocalize identical peptides, thus facilitating their collective presentation. Concentrations of self-proteins are fine-tuned over evolutionary time to avoid this. Disparate observations, such as pyrexia and female susceptibility to autoimmune disease, can be explained in terms of the need to cosegregate cognate pMHC complexes internally before extracellular display.
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Cocco E, Meloni A, Murru MR, Corongiu D, Tranquilli S, Fadda E, Murru R, Schirru L, Secci MA, Costa G, Asunis I, Cuccu S, Fenu G, Lorefice L, Carboni N, Mura G, Rosatelli MC, Marrosu MG. Vitamin D responsive elements within the HLA-DRB1 promoter region in Sardinian multiple sclerosis associated alleles. PLoS One 2012; 7:e41678. [PMID: 22848563 PMCID: PMC3404969 DOI: 10.1371/journal.pone.0041678] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 06/24/2012] [Indexed: 12/22/2022] Open
Abstract
Vitamin D response elements (VDREs) have been found in the promoter region of the MS-associated allele HLA-DRB1*15:01, suggesting that with low vitamin D availability VDREs are incapable of inducing *15:01 expression allowing in early life autoreactive T-cells to escape central thymic deletion. The Italian island of Sardinia exhibits a very high frequency of MS and high solar radiation exposure. We test the contribution of VDREs analysing the promoter region of the MS-associated DRB1 *04:05, *03:01, *13:01 and *15:01 and non-MS-associated *16:01, *01, *11, *07:01 alleles in a cohort of Sardinians (44 MS patients and 112 healthy subjects). Sequencing of the DRB1 promoter region revealed a homozygous canonical VDRE in all *15:01, *16:01, *11 and in 45/73 *03:01 and in heterozygous state in 28/73 *03:01 and all *01 alleles. A new mutated homozygous VDRE was found in all *13:03, *04:05 and *07:01 alleles. Functionality of mutated and canonical VDREs was assessed for its potential to modulate levels of DRB1 gene expression using an in vitro transactivation assay after stimulation with active vitamin D metabolite. Vitamin D failed to increase promoter activity of the *04:05 and *03:01 alleles carrying the new mutated VDRE, while the *16:01 and *03:01 alleles carrying the canonical VDRE sequence showed significantly increased transcriptional activity. The ability of VDR to bind the mutant VDRE in the DRB1 promoter was evaluated by EMSA. Efficient binding of VDR to the VDRE sequence found in the *16:01 and in the *15:01 allele reduced electrophoretic mobility when either an anti-VDR or an anti-RXR monoclonal antibody was added. Conversely, the Sardinian mutated VDRE sample showed very low affinity for the RXR/VDR heterodimer. These data seem to exclude a role of VDREs in the promoter region of the DRB1 gene in susceptibility to MS carried by DRB1* alleles in Sardinian patients.
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Affiliation(s)
- Eleonora Cocco
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Alessandra Meloni
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche (CNR), Cagliari, Italy
| | - Maria Rita Murru
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Daniela Corongiu
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Stefania Tranquilli
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Elisabetta Fadda
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Raffaele Murru
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Lucia Schirru
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Maria Antonietta Secci
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Gianna Costa
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Isadora Asunis
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche (CNR), Cagliari, Italy
| | - Stefania Cuccu
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Giuseppe Fenu
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Lorena Lorefice
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Nicola Carboni
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Gioia Mura
- Centro di Psichiatria e Psicosomatica Azienda Ospedaliera Universitaria, Cagliari, Italy
| | - Maria Cristina Rosatelli
- Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
| | - Maria Giovanna Marrosu
- Centro Sclerosi Multipla, Dipartimento di Sanità pubblica, Medicina clinica e molecolare, University of Cagliari, Cagliari, Italy
- * E-mail:
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10
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Anikeeva N, Sykulev Y. Mechanisms controlling granule-mediated cytolytic activity of cytotoxic T lymphocytes. Immunol Res 2012; 51:183-94. [PMID: 22058021 DOI: 10.1007/s12026-011-8252-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Cytotoxic T lymphocytes (CTL) play a critical role in immunity against viruses and cancer. The antigen receptor or T-cell receptor (TCR) on CTL determines the specificity toward target cells. The CD8 co-receptor functions in concert with the TCR to enhance TCR-mediated signaling, accounting for the remarkable sensitivity and swift signaling kinetics of the CTL response. The latter ensures efficient delivery and release of lytic granules, resulting in sensitive and rapid destruction of target cells.
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Affiliation(s)
- Nadia Anikeeva
- Department of Microbiology and Immunology, Kimmel Cancer Center and Jefferson Vaccine Center, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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11
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Seledtsov V, Seledtsova G. A balance between tissue-destructive and tissue-protective immunities: A role of toll-like receptors in regulation of adaptive immunity. Immunobiology 2012; 217:430-5. [PMID: 22099351 DOI: 10.1016/j.imbio.2011.10.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 10/21/2011] [Accepted: 10/21/2011] [Indexed: 12/12/2022]
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12
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Liu B, Fu Y, Wang Z, Zhou S, Sun Y, Wu Y, Xu A. HLA-DRB1 may be antagonistically regulated by the coordinately evolved promoter and 3'-UTR under stabilizing selection. PLoS One 2011; 6:e25794. [PMID: 22028790 PMCID: PMC3196528 DOI: 10.1371/journal.pone.0025794] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 09/11/2011] [Indexed: 11/18/2022] Open
Abstract
HLA-DRB1 is the most polymorphic MHC (major histocompatibility complex) class II gene in human, and plays a crucial role in the development and function of the immune system. Extensive polymorphisms exist in the promoter and 3'-UTR of HLA-DRB1, especially a LTR (Long terminal repeat) element in the promoter, which may be involved in the expression regulation. However, it remains unknown how the polymorphisms in the whole promoter region and 3'-UTR to regulate the gene expression. In this study, we investigated the extensive polymorphisms in the HLA-DRB1 promoter and 3'-UTR, and how these polymorphisms affect the gene expression in both independent and jointly manners. It was observed that most of the haplotypes in the DRB1 promoter and 3'-UTR were clustered into 4 conserved lineages (H1, H2, H3 and H4), and showed high linkage disequilibrium. Compared with H1 and H2 lineage, a LTR element in the promoter of H3 and H4 lineage significantly suppressed the promoter activity, whereas the activity of the linked 3'-UTR increased, leading to no apparent difference in the final expression product between H1/H2 and H3/H4 lineage. Nevertheless, compared with the plasmid with a promoter and 3'-UTR from the same lineage, the recombinant plasmid with a promoter from H2 and a 3'-UTR from H3 showed about double fold increased luciferase activity, Conversely, the recombinant plasmid with a promoter from H3 and a 3'-UTR from H2 resulted in about 2-fold decreased luciferase activity. These results indicate that the promoter and 3'-UTR of HLA-DRB1 may antagonistically regulate the gene expression, which may be subjected to stabilizing selection. These findings may provide a novel insight into the mechanisms of the diseases associated with HLA-DRB1 genes.
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Affiliation(s)
- Benrong Liu
- State Key Laboratory of Biocontrol, Guangdong Province Key Laboratory of Pharmaceutic Functional Genes, Department of Biochemistry, College of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou, People's Republic of China
| | - Yonggui Fu
- State Key Laboratory of Biocontrol, Guangdong Province Key Laboratory of Pharmaceutic Functional Genes, Department of Biochemistry, College of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou, People's Republic of China
| | - Zhifen Wang
- State Key Laboratory of Biocontrol, Guangdong Province Key Laboratory of Pharmaceutic Functional Genes, Department of Biochemistry, College of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou, People's Republic of China
| | - Sisi Zhou
- State Key Laboratory of Biocontrol, Guangdong Province Key Laboratory of Pharmaceutic Functional Genes, Department of Biochemistry, College of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou, People's Republic of China
| | - Yu Sun
- State Key Laboratory of Biocontrol, Guangdong Province Key Laboratory of Pharmaceutic Functional Genes, Department of Biochemistry, College of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou, People's Republic of China
| | - Yuping Wu
- State Key Laboratory of Biocontrol, Guangdong Province Key Laboratory of Pharmaceutic Functional Genes, Department of Biochemistry, College of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou, People's Republic of China
| | - Anlong Xu
- State Key Laboratory of Biocontrol, Guangdong Province Key Laboratory of Pharmaceutic Functional Genes, Department of Biochemistry, College of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou, People's Republic of China
- * E-mail:
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13
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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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14
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Abstract
T cell factor-1 (TCF1) critically regulates T cell development. However, signals that control TCF1 function in developing and mature T cells remain unknown. TCF1 along with beta-catenin activates gene transcription and in cooperation with Groucho family of proteins mediates gene repression. It has been established that the beta-catenin-dependent gene expression is often downstream of the canonical Wnt signaling pathway. We have genetically manipulated the beta-catenin gene and generated mutant mice that have shown an essential role for beta-catenin and TCF1 during pre-T cell receptor (TCR) and TCR-dependent stages of T cell development. We have also demonstrated a function for TCF1 and beta-catenin downstream of TCR signaling in the differentiation of mature CD4 T cells into T helper lineages.
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15
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Csorba TR, Lyon AW, Hollenberg MD. Autoimmunity and the pathogenesis of type 1 diabetes. Crit Rev Clin Lab Sci 2010; 47:51-71. [DOI: 10.3109/10408361003787171] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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16
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Varga I, Jablonska V, Cingel V, Kubikova E, Dorko F, Polak S. The first histological and immunohistochemical examination of thymus in a case of fetus in fetu. Ann Anat 2010; 192:232-6. [PMID: 20634048 DOI: 10.1016/j.aanat.2010.05.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 05/22/2010] [Accepted: 05/24/2010] [Indexed: 02/03/2023]
Abstract
Fetus in fetu (FIF) is a rare condition with less than 150 cases reported in the world to the best of our knowledge. It is a malformed monozygotic twin ("non-dominant twin"), which is found inside the body of a living child or sometimes in an adult ("dominant twin"). Different organs can be seen in these fetuses; vertebral column limbs, central nervous system, gastrointestinal tract, vessels, and genitourinary tract. In the literature, we found only two cases of fetus in fetu with the present thymic tissue. In this paper, the thymus of non-dominant twin exteriorized from the mediastini of dominant twin, was analyzed by histological and imunohistochemical methods. Even though the majority of organs did not develop normally in the mentioned case, thymic tissue was proved to be present in many body parts of the non-dominant twin. In spite of the fact that the cortex and the medulla were not so distinguishable as in the normal thymuses, presence of many basic cell populations was demonstrated: thymic epithelial cells (AE1/AE3 positive cells), T (CD45RO positive) and B (CD20 positive) cells, macrophages (CD68 positive cells), dendritic cells (S100 positive cells) and myoid cells (desmin positive). The Hassall's bodies were localized mostly in the medulla, however in sporadic cases they occurred in the area close to the connective tissue septa. The superficial epithelial cells of the Hassall's corpuscules as well as their internal contents, were markedly stained by alcian blue, and the cystic formations, found inside the Hassall's bodies, contained PAS-positive substance, similar to Hassall's bodies of normal thymuses. This fact indicates that although development of the parasitic twin is incomplete, all three germ layers participate on its development.
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Affiliation(s)
- Ivan Varga
- Department of Histology and Embryology, Comenius University in Bratislava, Slovakia.
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17
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Grb2 functions at the top of the T-cell antigen receptor-induced tyrosine kinase cascade to control thymic selection. Proc Natl Acad Sci U S A 2010; 107:10620-5. [PMID: 20498059 DOI: 10.1073/pnas.0905039107] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Grb2 is an adaptor molecule that mediates Ras-MAPK activation induced by various receptors. Here we show that conditional ablation of Grb2 in thymocytes severely impairs both thymic positive and negative selections. Strikingly, the mutation attenuates T-cell antigen receptor (TCR) proximal signaling, including tyrosine phosphorylation of multiple signaling proteins and Ca(2+) influx. The defective TCR signaling can be attributed to a marked impairment in Lck activation. Ectopic expression of a mutant Grb2 composed of the central SH2 and the C-terminal SH3 domains in Grb2(-/-) thymocytes fully restores thymocyte development. Thus, Grb2 plays a pivotal role in both thymic positive and negative selection. It amplifies TCR signaling at the top end of the tyrosine phosphorylation cascade via a scaffolding function.
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18
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Atibalentja DF, Byersdorfer CA, Unanue ER. Thymus-blood protein interactions are highly effective in negative selection and regulatory T cell induction. THE JOURNAL OF IMMUNOLOGY 2010; 183:7909-18. [PMID: 19933868 DOI: 10.4049/jimmunol.0902632] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Using hen egg-white lysozyme, the effect of blood proteins on CD4 thymic cells was examined. A small fraction of i.v. injected hen egg-white lysozyme rapidly entered the thymus into the medulla. There it was captured and presented by dendritic cells (DCs) to thymocytes from two TCR transgenic mice, one directed to a dominant peptide and a second to a poorly displayed peptide, both presented by MHC class II molecules I-A(k). Presentation by DC led to negative selection and induction of regulatory T cells, independent of epithelial cells. Presentation took place at very low levels, less than 100 peptide-MHC complexes per DC. Such low levels could induce negative selection, but even lower levels could induce regulatory T cells. The anatomy of the thymus-blood barrier, the highly efficient presentation by DC, together with the high sensitivity of thymic T cells to peptide-MHC complexes, results in blood protein Ags having a profound effect on thymic T cells.
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Affiliation(s)
- Danielle F Atibalentja
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110, USA
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19
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Crites TJ, Varma R. On the issue of peptide recognition in T cell development. SELF/NONSELF 2010; 1:55-61. [PMID: 21559177 PMCID: PMC3091603 DOI: 10.4161/self.1.1.10962] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 12/16/2009] [Accepted: 12/17/2009] [Indexed: 11/19/2022]
Abstract
CD4-CD8 double positive (DP) thymocytes undergo a differentiation process in the thymus where they are selected based on their ability to recognize peptide antigens presented on self major histocompatibility complex (MHC) molecules. The first stage of this process is positive selection, a quality-control mechanism which ensures that the T cell receptors (TCR) presented on developing thymocytes can transmit signals via peptides presented on either MHC class I (MHC1) or MHC class II (MHC2) molecules. Work over the past decade has revealed that the peptides that drive positive selection of both CD4 and CD8 lineage cells deliver only weak TCR signals. In line with these observations, specialized protein degradation machineries have been discovered in the thymic cortex that presumably generate specialized low-affinity peptide repertoires for presentation on MHC1 and MHC2 molecules. TCR signals transduced through these weak-affinity ligands in the early stages of positive selection alter the kinetics of expression of CD4 and CD8 molecules and play a crucial role in commitment of thymocytes to either the CD4 or CD8 lineages. In this work, we review the experiments that explore the peptide repertoires that are presented to developing thymocytes during positive selection, the observed signaling patterns that lead to CD4 versus CD8 lineage commitment, and speculate about how specialized organization of the signaling machinery in DP thymocytes may allow for efficient transduction of weak signals during the course of positive selection.
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Affiliation(s)
- Travis J Crites
- Laboratory of Cellular and Molecular Immunology; National Institute of Allergy and Infectious Diseases; National Institutes of Health; Bethesda, MD USA
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20
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Tian J, Dang H, von Boehmer H, Jaeckel E, Kaufman DL. Transgenically induced GAD tolerance curtails the development of early beta-cell autoreactivities but causes the subsequent development of supernormal autoreactivities to other beta-cell antigens. Diabetes 2009; 58:2843-50. [PMID: 19741165 PMCID: PMC2780885 DOI: 10.2337/db08-0851] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To study how tolerance to GAD65 affects the development of autoimmunity to other beta-cell autoantigens (beta-CAAs) in GAD65-transgenic (GAD-tg) NOD mice. RESEARCH DESIGN AND METHODS We used ELISPOT to characterize the frequency and functional phenotype of T-cell responses to GAD65 and other beta-CAAs at different ages in GAD-tg mice and their NOD mouse littermates. RESULTS In young GAD-tg mice, Th1 responses to GAD65's dominant determinants were 13-18% of those in young NOD mice. This coincided with a great reduction in Th1 responses to other beta-CAAs. Evidently, GAD65-reactive T-cells are important for activating and/or expanding early autoreactivities in NOD mice. As GAD-tg mice aged, their T-cell responses to GAD65 remained low, but they developed supernormal splenic and pancreatic lymph node T-cell autoimmunity to other beta-CAAs. Apparently, the elimination/impairment of many GAD65-reactive T-cells allowed other beta-CAA-reactive T-cells to eventually expand to a greater extent, perhaps by reducing competition for antigen-presenting cells, or homeostatic proliferation in the target tissue, which may explain the GAD-tg mouse's usual disease incidence. CONCLUSIONS Transgenically induced reduction of GAD65 autoreactivity curtailed the development of early T-cell responses to other beta-CAAs. However, later in life, beta-CAA-reactive T-cells expanded to supernormal levels. These data suggest that early beta-cell autoreactivities are mutually dependent for support to activate and expand, while later in the disease process, autoantigen-specific T-cell pools can expand autonomously. These findings have implications for understanding type 1 diabetes immunopathogenesis and for designing antigen-based immunotherapeutics.
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Affiliation(s)
- Jide Tian
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California
| | - Hoa Dang
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California
| | - Harald von Boehmer
- Laboratory of Lymphocyte Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts
| | - Elmar Jaeckel
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Daniel L. Kaufman
- Department of Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, California
- Corresponding author: Daniel L. Kaufman,
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21
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Brodeur JF, Li S, Damlaj O, Dave VP. Expression of fully assembled TCR-CD3 complex on double positive thymocytes: synergistic role for the PRS and ER retention motifs in the intra-cytoplasmic tail of CD3epsilon. Int Immunol 2009; 21:1317-27. [PMID: 19819936 DOI: 10.1093/intimm/dxp098] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
TCR expression on double-positive (DP) thymocytes is a prerequisite for thymic selection that results in the generation of mature CD4(+) and CD8(+) single-positive T cells. TCR is expressed at very low level on preselection DP thymocytes and is dramatically up-regulated on positively selected thymocytes. However, mechanism governing TCR expression on developing thymocytes is not understood. In the present report, we demonstrate that the intra-cytoplasmic (IC) domain of CD3epsilon plays a critical role in regulating TCR expression on DP thymocytes. We provide genetic and biochemical evidence to show that the CD3epsilon IC domain mutations result in elevated expression of fully assembled TCR on DP thymocytes. We also demonstrate that TCR up-regulation on DP thymocytes in these transgenic mice occurs in a ligand-independent manner. Further, we show that the proline-rich sequence and endoplasmic reticulum (ER) retention motifs in the IC domain of CD3epsilon play synergistic role in regulating TCR surface expression on DP thymocytes.
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Affiliation(s)
- Jean-Francois Brodeur
- Lymphocyte Development Laboratory, Institut de Recherches Cliniques de Montreal, Montreal, Quebec, Canada H2W 1R7
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22
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Wakimoto T, Tomisaka R, Nishikawa Y, Sato H, Yoshino T, Takahashi K. Identification and characterization of human thymic cortical dendritic macrophages that may act as professional scavengers of apoptotic thymocytes. Immunobiology 2008; 213:837-47. [PMID: 18926298 DOI: 10.1016/j.imbio.2008.07.032] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Accepted: 07/23/2008] [Indexed: 11/29/2022]
Abstract
We identify and characterize a special type of macrophage in the human thymic cortex that may act as professional scavengers of apoptotic thymocytes. These are large cells with clear cytoplasm, evenly distributed exclusively in the thymic cortex, and usually contain degraded nuclei in their cytoplasm. They are distinct from ordinary macrophages (OM) in the thymic cortex in expressing fascin, an actin-bundling protein specific for dendritic cells (DC), and in lacking lysozyme (LZM) and CD68. They are also different from DC in lacking major histocompatibility complex (MHC)-class II molecules. To distinguish them from OM and DC, we called them thymic cortical dendritic macrophages (TCDM). Both TCDM and OM are positive for DC-SIGN (CD209) and HAM56, whereas fascin(hi) MHC-class II(hi) medullary DC (mDC) are negative for these antigens. TCDM exhibit either dendritic or plump feature depending on cases examined. Plump TCDM usually contain several degraded nuclei, while dendritic TCDM contain one or two. These degraded nuclei are positive for active caspase-3 (aCasp-3), indicating that they are apoptotic thymocytes. In contrast to TCDM, LZM(hi) CD68(hi) OM are smaller round cells, distributed unevenly throughout the thymus, and do not contain apoptotic thymocytes at all. TCDM tend to adhere to capillaries with their dendrites or they make extensive contacts covering a large portion of the capillaries. Electron microscopic analysis confirmed the extensive contact between TCDM and capillaries and indicated that TCDM possess extremely electron-lucent, abundant cytoplasm with numerous tubulovesicular structures and secondary lysosomes. The finding of numerous condensed nuclei in most of the TCDM indicates that these cells represent a special type of fixed macrophages in the human thymic cortex, and that they play a central role in the clearance of apoptotic thymocytes.
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Affiliation(s)
- Taku Wakimoto
- Faculty of Health Science, Postgraduate School of Okayama University, Shikata-cho 2-5-1, Okayama-city 700-8558, Japan
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23
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Riddle DS, Miller PJ, Vincent BG, Kepler TB, Maile R, Frelinger JA, Collins EJ. Rescue of cytotoxic function in the CD8alpha knockout mouse by removal of MHC class II. Eur J Immunol 2008; 38:1511-21. [PMID: 18465769 DOI: 10.1002/eji.200737710] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
CD8 plays an important role in the activity of cytolytic T cells (CTL). However, whether or not CD8 is required for the development of CTL has not been clearly determined. Cytotoxic activity in the CD8alpha knockout mouse is difficult to induce, and has only been demonstrated against allogenic MHC targets. The lack of cytotoxicity may result from impaired lineage commitment of CTL in the absence of CD8, or diminished competitiveness during selection against (unimpaired) development of CD4(+) T cells on MHC class II (MHC II). To differentiate between these possibilities, we have generated a double-knockout mouse (MHC II(-/-)CD8alpha(-/-)). In MHC II(-/-)CD8alpha(-/-) mice, developing MHC class I (MHC I)-reactive thymocytes cannot rely upon CD8 for selection, but they also cannot be overwhelmed by efficient selection of MHC II-reactive thymocytes. In this mouse, a large, heterogeneous population of peripheral coreceptor double-negative (DN) and CD4(+) T cells develops. Peripheral DN T cells are fully functional CTL. They display cytolytic activity against allogeneic MHC, and against syngeneic MHC following lymphocytic choriomeningitis virus (LCMV) infection. Cells from LCMV-infected mice bind more MHC I tetramer at lower concentrations than their wild-type CTL counterparts. These results demonstrate unequivocally that CD8 is not required for commitment of thymocytes to the CTL lineage.
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Affiliation(s)
- David S Riddle
- University of North Carolina at Chapel Hill, Department of Microbiology and Immunology, Chapel Hill, NC 27599-7290, USA
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24
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Chidgey AR, Boyd RL. Thymic stromal cells and positive selection. APMIS 2008. [DOI: 10.1111/j.1600-0463.2001.907801.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Van Wijmeersch B, Sprangers B, Dubois B, Waer M, Billiau AD. Autologous and allogeneic hematopoietic stem cell transplantation for Multiple Sclerosis: perspective on mechanisms of action. J Neuroimmunol 2008; 197:89-98. [PMID: 18541311 DOI: 10.1016/j.jneuroim.2008.04.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 04/24/2008] [Accepted: 04/25/2008] [Indexed: 12/29/2022]
Abstract
Multiple Sclerosis (MS) is a frequent demyelinating immune-mediated disease of the central nervous system (CNS) that affects principally young adults and leads to severe physical and cognitive impairment. The current standard treatment makes use of the immune modulators beta-interferon, glatiramer acetate and natalizumab, or immunosuppressants such as mitoxantrone. However, these agents are only partially effective and in a number of patients fail to achieve satisfactory disease control. Autologous hematopoietic stem cell transplantation (HSCT) is being explored in the treatment of severe MS as a means of delivering high-dose immunosuppression followed by 'rescue' of the immuno-hematopoietic system with autologous HSC. The potential therapeutic benefit is based on the concept of so-called 'resetting' the immune system. The use of allogeneic HSCT as a possible therapeutic approach for severe MS is inspired by case reports of MS patients that underwent allogeneic HSCT for a concomitant hematological malignancy, and subsequently is supported by data from rodent models of MS. Allogeneic HSCT may offer specific therapeutic effects, such as the replacement of the autoreactive immune compartment by healthy allogeneic cells and the development of a graft-versus-autoimmunity (GVA) effect. Here, we review the currently available experimental and clinical evidence to support the role of autologous and allogeneic HSCT in MS.
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26
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Okumura M, Fujii Y, Shiono H, Inoue M, Minami M, Utsumi T, Kadota Y, Sawa Y. Immunological function of thymoma and pathogenesis of paraneoplastic myasthenia gravis. Gen Thorac Cardiovasc Surg 2008; 56:143-50. [PMID: 18401674 DOI: 10.1007/s11748-007-0185-8] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Indexed: 11/26/2022]
Abstract
Thymoma and thymic carcinoma are the representative tumors arising from the thymic epithelium. Thymoma is well known for association with autoimmune diseases including myasthenia gravis, suggesting its biological activity. Herein, recent progress in research of thymoma is reviewed with reference to its immunological function. Myasthenia gravis is frequently associated with WHO type B1 and B2 thymomas. These types of thymomas hold a significant number of CD4(+)CD8(+) double-positive T cells, and at the same time, the neoplastic epithelial cells express HLA-DR molecules at a slightly reduced level compared with the normal thymus. The impaired expression of HLA-DR molecules in neoplastic epithelial cells of thymomas possibly affects positive selection of CD4(+)CD8(-) single-positive T cells and may result in alteration of its repertoire. The function of thymoma neoplastic cells as the cortical epithelium of the thymus and the morphological resemblance of thymomas to the cortex suggest that thymoma is of cortical epithelial origin; this might imply that thymoma lacks the functional medulla where professional antigen-presenting cells are engaged in negative selection. These findings suggest that thymoma generates autoreactive T cells causing autoimmunity. Further investigation on immunological function of thymoma is supposed to elucidate the pathogenesis of thymoma-related autoimmunity and the high affinity of thymoma with myasthenia gravis. In addition, studying the biology of thymoma is also expected to contribute to further understanding of T-cell development and immunological tolerance in the human, because thymoma can be considered an acquired thymus.
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Affiliation(s)
- Meinoshin Okumura
- Department of General Thoracic Surgery (L5), Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka, 565-0871, Japan.
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27
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Kiss I, Rühl R, Szegezdi E, Fritzsche B, Tóth B, Pongrácz J, Perlmann T, Fésüs L, Szondy Z. Retinoid receptor-activating ligands are produced within the mouse thymus during postnatal development. Eur J Immunol 2008; 38:147-55. [PMID: 18085670 DOI: 10.1002/eji.200737342] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Vitamin A deficiency is known to be accompanied with immune deficiency and susceptibility to a wide range of infectious diseases. Experimental evidence suggests that the active metabolites of vitamin A that mediate its effects on the immune system are the retinoic acids (RA), which are ligands for the nuclear RA receptor (RAR) family. RA were previously shown both to promote proliferation and to regulate apoptosis of thymocytes. In this study we detected the age-dependent mRNA expression of retinaldehyde dehydrogenases (RALDH1 and 2), cellular RA binding protein-II and CYP26A, proteins responsible for the synthesis, nuclear transport and degradation of RA in the postnatally developing thymus. RALDH1 was located in thymic epithelial cells. However, the amount of all-trans RA in thymic homogenates was close to the detection limit, suggesting that in this tissue all-trans RA is not the main RAR-regulating product of retinol metabolism. At the same time, by measuring the induction of a RAR-responsive transgene in two independent transgenic mouse strains, we demonstrated the production of an RAR-activating ligand, which was age and RALDH dependent. Our data provide evidence for the existence of endogenous retinoid synthesis in the thymus and suggest that retinoids similar to glucocorticoids might indeed be involved in the regulation of thymic proliferation and selection processes by being present in the thymus in functionally effective amounts.
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Affiliation(s)
- Ildikó Kiss
- Department of Biochemistry and Molecular Biology, Signaling and Apoptosis Research Group, Hungarian Academy of Sciences, Research Center of Molecular Medicine, University of Debrecen, Debrecen, Hungary
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28
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Cohn M. The Tritope Model for restrictive recognition of antigen by T-cells II. Implications for ontogeny, evolution and physiology. Mol Immunol 2008; 45:632-52. [PMID: 17889366 PMCID: PMC2104471 DOI: 10.1016/j.molimm.2006.02.033] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2005] [Accepted: 02/01/2006] [Indexed: 12/19/2022]
Abstract
Based on the Tritope Model of the TCR [Cohn, M., 2005c. The Tritope Model for restrictive recognition of antigen by T-cells. I. What assumptions about structure are needed to explain function? Mol. Immunol. 42, 1419-1443], a set of functional and evolutionary problems surrounding restrictive recognition of antigen are discussed. These include the origin of allele-specific recognition, the selection pressures for polygeneism and polymorphism, the TCR signaling interactions, the centrality of effector T-helper (eTh)-dependence for activation, the role of haplotype exclusion, "nonclassical" MHC-elements, alloreactivity versus xenoreactivity, etc. Further, a set of observations believed to support the Standard Model are reinterpreted.
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Affiliation(s)
- Melvin Cohn
- Conceptual Immunology Group, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, United States.
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29
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Sommer N, Tackenberg B, Hohlfeld R. The immunopathogenesis of myasthenia gravis. HANDBOOK OF CLINICAL NEUROLOGY 2008; 91:169-212. [PMID: 18631843 DOI: 10.1016/s0072-9752(07)01505-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- Norbert Sommer
- Clinical Neuroimmunology Group, Philipps-University, Marburg, Germany
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30
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Nitta T, Murata S, Ueno T, Tanaka K, Takahama Y. Thymic microenvironments for T-cell repertoire formation. Adv Immunol 2008; 99:59-94. [PMID: 19117532 DOI: 10.1016/s0065-2776(08)00603-2] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Functionally competent immune system includes a functionally competent T-cell repertoire that is reactive to foreign antigens but is tolerant to self-antigens. The repertoire of T cells is primarily formed in the thymus through positive and negative selection of developing thymocytes. Immature thymocytes that undergo V(D)J recombination of T-cell antigen receptor (TCR) genes and that express the virgin repertoire of TCRs are generated in thymic cortex. The recent discovery of thymoproteasomes, a molecular complex specifically expressed in cortical thymic epithelial cells (cTEC), has revealed a unique role of cTEC in cuing the further development of immature thymocytes in thymic cortex, possibly by displaying unique self-peptides that induce positive selection. Cortical thymocytes that receive TCR-mediated positive selection signals are destined to survive for further differentiation and are induced to express CCR7, a chemokine receptor. Being attracted to CCR7 ligands expressed by medullary thymic epithelial cells (mTEC), CCR7-expressing positively selected thymocytes relocate to thymic medulla. The medullary microenvironment displays another set of unique self-peptides for trimming positively selected T-cell repertoire to establish self-tolerance, via promiscuous expression of tissue-specific antigens by mTEC and efficient antigen presentation by dendritic cells. Recent results demonstrate that tumor necrosis factor (TNF) superfamily ligands, including receptor activating NF-kappaB ligand (RANKL), CD40L, and lymphotoxin, are produced by positively selected thymocytes and pivotally regulate mTEC development and thymic medulla formation.
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Affiliation(s)
- Takeshi Nitta
- Division of Experimental Immunology, Institute for Genome Research, University of Tokushima, Tokushima 770-8503, Japan
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31
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van den Berg HA, Wooldridge L, Laugel B, Sewell AK. Coreceptor CD8-driven modulation of T cell antigen receptor specificity. J Theor Biol 2007; 249:395-408. [PMID: 17869274 PMCID: PMC6485485 DOI: 10.1016/j.jtbi.2007.08.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Revised: 07/25/2007] [Accepted: 08/01/2007] [Indexed: 11/22/2022]
Abstract
The CD8 coreceptor modulates the interaction between the T cell antigen receptor (TCR) and peptide-major histocompatibility class I (pMHCI). We present evidence that CD8 not only modifies the affinity of cognate TCR/pMHCI binding by altering both the association rate and the dissociation rate of the TCR/pMHCI interaction, but modulates the sensitivity (triggering threshold) of the TCR as well, by recruiting TCR/pMHCI complexes to membrane microdomains at a rate which depends on the affinity of MHCI/CD8 binding. Mathematical analysis of these modulatory effects indicates that a T cell can alter its functional avidity for its agonists by regulating CD8 expression, and can rearrange the relative potencies of each of its potential agonists. Thus we propose that a T cell can specifically increase its functional avidity for one agonist, while decreasing its functional avidity for other potential ligands. This focussing mechanism means that TCR degeneracy is inherently dynamic, allowing each TCR clonotype to have a wide range of agonists while avoiding autorecognition. The functional diversity of the TCR repertoire would therefore be greatly augmented by coreceptor-mediated ligand focussing.
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Affiliation(s)
- Hugo A van den Berg
- Warwick Systems Biology Centre, Coventry House, University of Warwick, Coventry CV4 7AL, UK.
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32
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Developmentally regulated promoter-switch transcriptionally controls Runx1 function during embryonic hematopoiesis. BMC DEVELOPMENTAL BIOLOGY 2007; 7:84. [PMID: 17626615 PMCID: PMC1941738 DOI: 10.1186/1471-213x-7-84] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Accepted: 07/12/2007] [Indexed: 12/31/2022]
Abstract
Background Alternative promoters usage is an important paradigm in transcriptional control of mammalian gene expression. However, despite the growing interest in alternative promoters and their role in genome diversification, very little is known about how and on what occasions those promoters are differentially regulated. Runx1 transcription factor is a key regulator of early hematopoiesis and a frequent target of chromosomal translocations in acute leukemias. Mice deficient in Runx1 lack definitive hematopoiesis and die in mid-gestation. Expression of Runx1 is regulated by two functionally distinct promoters designated P1 and P2. Differential usage of these two promoters creates diversity in distribution and protein-coding potential of the mRNA transcripts. While the alternative usage of P1 and P2 likely plays an important role in Runx1 biology, very little is known about the function of the P1/P2 switch in mediating tissue and stage specific expression of Runx1 during development. Results We employed mice bearing a hypomorphic Runx1 allele, with a largely diminished P2 activity, to investigate the biological role of alternative P1/P2 usage. Mice homozygous for the hypomorphic allele developed to term, but died within a few days after birth. During embryogenesis the P1/P2 activity is spatially and temporally modulated. P2 activity is required in early hematopoiesis and when attenuated, development of liver hematopoietic progenitor cells (HPC) was impaired. Early thymus development and thymopoiesis were also abrogated as reflected by thymic hypocellularity and loss of corticomedullary demarcation. Differentiation of CD4/CD8 thymocytes was impaired and their apoptosis was enhanced due to altered expression of T-cell receptors. Conclusion The data delineate the activity of P1 and P2 in embryogenesis and describe previously unknown functions of Runx1. The findings show unequivocally that the role of P1/P2 during development is non redundant and underscore the significance of alternative promoter usage in Runx1 biology.
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Abstract
We review recent advances toward a comprehensive mathematical theory of T-cell immunity. A key insight is that the efficacy of the T-cell response is best analyzed in terms of T-cell receptor (TCR) avidity and the distribution of this avidity across the TCR repertoire (the 'avidity spectrum'). Modification of this avidity spectrum by a wide range of tuning and tolerance mechanisms allows the system to adapt cross-reactivity and specificity to the challenge at hand while avoiding inappropriate responses against non-pathogenic cells and tissues. Theoretical models relate molecular kinetic parameters and cellular properties to systemic level statistics such as avidity spectra. Such bridge equations are crucial for rational clinical manipulation of T cells at the molecular level.
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Affiliation(s)
- Hugo A van den Berg
- Warwick Systems Biology Centre, Mathematics Institute, University of Warwick, Coventry, UK.
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Van Wijmeersch B, Sprangers B, Rutgeerts O, Lenaerts C, Landuyt W, Waer M, Billiau AD, Dubois B. Allogeneic bone marrow transplantation in models of experimental autoimmune encephalomyelitis: evidence for a graft-versus-autoimmunity effect. Biol Blood Marrow Transplant 2007; 13:627-37. [PMID: 17531772 DOI: 10.1016/j.bbmt.2007.03.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Accepted: 03/05/2007] [Indexed: 12/29/2022]
Abstract
Autologous hematopoietic stem cell transplantation (HSCT) is being explored in the treatment of severe multiple sclerosis (MS), and is based on the concept of "resetting" the immune system. The use of allogeneic HSCT may offer additional advantages, such as the replacement of the autoreactive immune compartment by healthy allogeneic cells and development of a graft-versus-autoimmunity (GVA) effect. However, in clinical practice, the genetic susceptibility to MS of allogeneic stem cell donors is generally unknown, and GVA may therefore be an important mechanism of action. Experimental autoimmune encephalomyelitis (EAE)-susceptible and -resistant mouse strains were used to determine the roles of genetic susceptibility, level of donor-chimerism, and alloreactivity in the therapeutic potential of syngeneic versus allogeneic bone marrow transplant (BMT) for EAE. After transplantation and EAE induction, animals were evaluated for clinical EAE and ex vivo myelin oligodendrocyte glycoprotein-specific proliferation. Early after BMT, both syngeneic and allogeneic chimeras were protected from EAE development. On the longer term, allogeneic but not syngeneic BMT conferred protection, but this required high-level donor-chimerism from EAE-resistant donors. Importantly, when EAE-susceptible donors were used, robust protection from EAE was obtained when active alloreactivity, induced by donor lymphocyte infusions, was provided. Our findings indicate the requirement of a sufficient level of donor-chimerism from a nonsusceptible donor in the therapeutic effect of allogeneic BMT. Importantly, the data indicate that, independently of genetic susceptibility, active alloreactivity is associated with a GVA effect, thereby providing new evidence to support the potential role of allogeneic BMT in the treatment of MS.
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Affiliation(s)
- Bart Van Wijmeersch
- Laboratory of Experimental Transplantation, University of Leuven, Leuven, Belgium
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35
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Abstract
Eph kinases are the largest family of receptor tyrosine kinases, and their ligands, ephrins (EFNs), are also cell surface molecules. In this study, we investigated the role of EFNB1 and the Ephs it interacts with (collectively called EFNB1 receptors) in mouse T-cell development. In the thymus, CD8 single positive (SP) and CD4CD8 double positive (DP) cells expressed high levels of EFNB1 and EFNB1 receptors, whereas CD4 SP cells had moderate expression of both. Soluble EFNB1-Fc in fetal thymus organ culture caused significant subpopulation ratio skew, with increased CD4 SP and CD8 SP and decreased DP percentage, while the cellularity of the thymus remained constant. Moreover, in EFNB1-treated fetal thymus organ culture, CD117(+), CD25(+), DP, CD4 SP, and CD8 SP cells all had significantly enhanced proliferation history, according to bromodeoxyuridine uptake. In vitro culture of isolated thymocytes revealed that EFNB1-Fc on solid-phase protected thymocytes from anti-CD3-induced apoptosis, with concomitant augmentation of several antiapoptotic factors, particularly in CD4 SP and CD8 SP cells; on the other hand, soluble EFNB1-Fc promoted anti-CD3-induced apoptosis, as was the case in vivo. This study reveals that EFNB1 and EFNB1 receptors are critical in thymocyte development.
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Affiliation(s)
- Guang Yu
- Laboratory of Immunology, Centre Hospitalier de l'Université de Montréal, Montréal, Quebec H2L 4M1, Canada
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36
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Muraro PA, Douek DC. Renewing the T cell repertoire to arrest autoimmune aggression. Trends Immunol 2006; 27:61-7. [PMID: 16406806 DOI: 10.1016/j.it.2005.12.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Revised: 11/21/2005] [Accepted: 12/08/2005] [Indexed: 01/16/2023]
Abstract
There is now evidence that high-dose immune ablation and autologous hematopoietic stem cell transplantation in humans triggers a reconstitution program that leads to the comprehensive renewal of the T cell repertoire. We argue here that several features of this program help to explain how autologous hematopoietic stem cell transplantation can induce long-term clinical remission from organ-specific-, as well as systemic, autoimmune diseases. We propose a model envisioning a coordinated sequence of events, rebuilding an immune system that is competent against infection but that is substantially reconfigured in a way that is less likely to redevelop autoimmunity.
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Affiliation(s)
- Paolo A Muraro
- Neuroimmunology Branch, NINDS/NIH, Bldg. 10, Room 5B16, 10 Center Drive, MSC1400, Bethesda, MD 20892-1400, USA.
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37
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Olcott AP, Tian J, Walker V, Dang H, Middleton B, Adorini L, Washburn L, Kaufman DL. Antigen-based therapies using ignored determinants of beta cell antigens can more effectively inhibit late-stage autoimmune disease in diabetes-prone mice. THE JOURNAL OF IMMUNOLOGY 2005; 175:1991-9. [PMID: 16034144 DOI: 10.4049/jimmunol.175.3.1991] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
As organ-specific autoimmune diseases do not become manifest until well-advanced, interventive therapies must inhibit late-stage disease processes. Using a panel of immunogenic peptides from various beta cell Ags, we evaluated the factors influencing the efficacy of Ag-based therapies in diabetes-prone NOD mice with advanced disease. The ability of the major beta cell autoantigen target determinants (TDs) to prime Th2 responses declined sharply between 6 and 12 wk of age, whereas the ability of immunogenic ignored determinants (IDs) of beta cell Ags to prime Th2 responses was unaffected by the disease process. The different patterns of TD and ID immunogenicity (even from the same beta cell Ag) may be due to the exhaustion of uncommitted TD-reactive, but not ID-reactive, T cell pools by recruitment into the autoimmune cascade. Therapeutic efficacy was associated with a peptide's immunogenicity and ability to promote Th2 spreading late in the disease process but not its affinity for I-Ag7 or its expression pattern (beta cell specific/nonspecific or rare/abundant). Characterization of some IDs revealed them to be "absolute" cryptic determinants. Such determinants have little impact on T cell selection, leaving large precursor T cell pools available for priming by synthetic peptides. Traditional Ag-based therapeutics using whole autoantigens or their TDs cannot prime responses to such determinants. These findings suggest a new strategy for designing more efficacious Ag-based therapeutics for late-stage autoimmune diseases.
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Affiliation(s)
- Angelica P Olcott
- Department of Molecular and Medical Pharmacology, University of California, School of Medicine, Los Angeles, CA 90095-1735, USA
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38
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Quast S, Zhang W, Shive C, Kovalovski D, Ott PA, Herzog BA, Boehm BO, Tary-Lehmann M, Karulin AY, Lehmann PV. IL-2 absorption affects IFN-γ and IL-5, but not IL-4 producing memory T cells in double color cytokine ELISPOT assays. Cell Immunol 2005; 237:28-36. [PMID: 16256965 DOI: 10.1016/j.cellimm.2005.09.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2005] [Revised: 09/06/2005] [Accepted: 09/08/2005] [Indexed: 01/31/2023]
Abstract
Cytokine assays are gaining increasing importance for human immune monitoring because they reliably detect antigen-specific T cells in primary PBMC, even at low clonal sizes. Double color ELISPOT assays permit the simultaneous visualization of cells producing two different cytokines. Permitting the simultaneous assessment of type 1 and 2 immunity and due to the limited numbers of PBMC available from human study subjects, double color assays should be particularly attractive for clinical trials. Since the performance of double color assays has not yet been validated, we set out to compare them to single color measurements. Testing the recall antigen-induced cytokine response of PBMC, we found that double color assays regularly provided lower numbers of IFN-gamma and IL-5 spots than single color measurements when IL-2 detection was part of the double color assay. We showed that the inhibitory effect resulted from IL-2 absorption and could be overcome by either antibody free preactivation cultures or by inclusion of anti-CD28 antibody. In contrast, the simultaneous detection of IL-2 did not affect the numbers of IL-4 spots. Therefore, unlike IL-2/IL-4 and IFN-gamma/IL-5 assays, IL-2/IFN-gamma, and IL-2/IL-5 assays require compensation for the IL-2 capture to provide accurate numbers for the frequencies of cytokine producing memory T cells.
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Affiliation(s)
- Stefan Quast
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA, and University Hospital of Ulm, Section of Endocrinology, Germany
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39
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Forsdyke DR. “Altered-self” or “near-self” in the positive selection of lymphocyte repertoires? Immunol Lett 2005; 100:103-6. [PMID: 15894383 DOI: 10.1016/j.imlet.2005.03.018] [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] [Received: 03/23/2005] [Accepted: 03/30/2005] [Indexed: 10/25/2022]
Abstract
Positive selection of lymphocyte repertoires is now recognized as applying to both B and T cells. However, much of the early literature on positive selection focussed on cell-mediated immunity (T cells), which biased consideration of its general biological role. The term "altered-self," which initially captured the idea of self (i.e. MHC) altered by the addition of what was later found to be a peptide fragment, has not proven robust and may now be clouding our understanding. It is recommended that the term "near-self" be reintroduced since it captures the essence of the probable underlying adaptive process-sub-threshold self-reactivity to countermand rapid pathogen mutation.
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Affiliation(s)
- Donald R Forsdyke
- Department of Biochemistry, Queen's University, Botterall Hall, Stuart Street, Kingston, Ontario, Canada K7L 3N6.
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40
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Kattman SJ, Lukin KR, Oh JZ, Berg RE, Staerz UD. Maturational stage-dependent thymocyte responses to TCR engagement. Eur J Immunol 2005; 35:2051-60. [PMID: 15915541 DOI: 10.1002/eji.200425293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Thymocyte positive and negative selection are dependent on avidity-driven TCR-mediated recognition events in the thymus. High-avidity recognition events result in negative selection, while low-avidity recognition events result in positive selection. However, it has not been established how thymocytes maturation stages affect their responses to TCR signals of different avidities. We gained insight into this question when we reduced thymocyte selection to an in vitro system, in which full maturation of developmentally synchronized immature double-positive thymocytes was induced on a cloned line of thymic epithelial cells. Our analysis of the kinetics of thymocyte development supports a multi-phasic model of thymic selection. In it, thymocyte maturation stages as well as interaction avidity control the outcome TCR stimulation. Positive selection is initiated during a primary recognition event that proceeds independently of the TCR avidity. During a secondary recognition event the final fate of thymocyte, full maturation versus negative selection, is determined by TCR avidity.
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Affiliation(s)
- Steven J Kattman
- Integrated Department of Immunology, National Jewish Medical and Research Center, Denver, CO, USA
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41
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Abstract
Our understanding of the classical MHC class I molecules (MHC class Ia molecules) has long focused on their extreme polymorphism. These molecules present peptides to T cells and are central to discrimination between self and non-self. By contrast, the functions of the non-polymorphic MHC class I molecules (MHC class Ib molecules) have been elusive, but emerging evidence reveals that, in addition to antigen presentation, MHC class Ib molecules are involved in immunoregulation. As we discuss here, the subset of MHC class Ib molecules that presents peptides to T cells bridges innate and acquired immunity, and this provides insights into the origins of acquired immunity.
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Affiliation(s)
- John R Rodgers
- Department of Immunology, Baylor College of Medicine, Houston, Texas 77030, USA.
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42
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Goldman KP, Park CS, Kim M, Matzinger P, Anderson CC. Thymic cortical epithelium induces self tolerance. Eur J Immunol 2005; 35:709-17. [PMID: 15719367 DOI: 10.1002/eji.200425675] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Because of its role in positive selection, the ability of cortical epithelium to induce tolerance is controversial. On the one hand, experiments with transplanted thymuses showed that the recipients were functionally tolerant of all the antigens expressed by the cells of those thymuses, including cells of the cortical epithelium. On the other, the keratin 14 (K14) transgenic mouse strain, which expresses MHC class II on cortical epithelium under the control of the K14 promoter, does not seem to be tolerant of the transgenic MHC molecule. Here we tested whether the lack of tolerance in the K14 mouse might be more apparent than real. We found that K14 mice are indeed completely tolerant of K14 cortical thymic epithelium, whereas they remain reactive to tissues that express the same MHC allele under normal genetic control. These results establish the ability of cortical epithelium to induce central tolerance, and impinge on several of the models concerning positive selection of newly developing T cells.
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43
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Hofstetter HH, Targoni OS, Karulin AY, Forsthuber TG, Tary-Lehmann M, Lehmann PV. Does the Frequency and Avidity Spectrum of the Neuroantigen-Specific T Cells in the Blood Mirror the Autoimmune Process in the Central Nervous System of Mice Undergoing Experimental Allergic Encephalomyelitis? THE JOURNAL OF IMMUNOLOGY 2005; 174:4598-605. [PMID: 15814682 DOI: 10.4049/jimmunol.174.8.4598] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In humans, studies of autoreactive T cells that mediate multiple sclerosis have been largely confined to testing peripheral blood lymphocytes. Little is known how such measurements reflect the disease-mediating autoreactive T cells in the CNS. This information is also not available for murine experimental allergic encephalomyelitis (EAE); the low number of T cells that can be obtained from the blood or the brain of mice prevented such comparisons. We used single-cell resolution IFN-gamma ELISPOT assays to measure the frequencies and functional avidities of myelin basic protein (MBP:87-99)-specific CD4 cells in SJL mice immunized with this peptide. Functional MBP:87-99-specific IFN-gamma-producing cells were present in the CNS during clinical signs of EAE, but not during phases of recovery. In contrast, MBP:87-99-specific T cells persisted in the blood during all stages of the disease, and were also present in mice that did not develop EAE. Therefore, the increased frequency of MBP:87-99-reactive T cells in the blood reliably reflected the primed state, but not the inflammatory activity of these cells in the brain. The functional avidity of the MBP:87-99-reactive T cells was identical in the brain and blood and did not change over 2 mo as the mice progressed from acute to chronic EAE. Therefore, high-affinity T cells did not become selectively enriched in the target organ, and avidity maturation of the MBP:87-99-specific T cell repertoire did not occur in the observation period. The data may help the interpretation of measurements made with peripheral blood lymphocytes of multiple sclerosis patients.
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Affiliation(s)
- Harald H Hofstetter
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4943, USA
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44
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Barkholt L, Löfberg R. Resetting the immune system in refractory Crohn's disease: is autologous hematopoietic stem cell transplantation the way forward? Gastroenterology 2005; 128:786-9. [PMID: 15765415 DOI: 10.1053/j.gastro.2005.01.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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45
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Mengel J, Fávaro P, Meyer A, Motta V, de Alencar R, Postól E, Cardillo F. Potentiation of immunological tolerance induction in adult mice by co-administration of pooled normal IgG and oral tolerogens: a potential therapeutic approach for autoimmune diseases. Med Hypotheses 2005; 64:978-85. [PMID: 15780495 DOI: 10.1016/j.mehy.2004.10.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2004] [Accepted: 10/26/2004] [Indexed: 10/26/2022]
Abstract
Oral tolerance can be defined as the inability of an adult animal to produce specific antibodies or cellular immune responses upon conventional immunization, after oral antigenic administration. Recently, the oral administration of antigens has gained renewed interest because of the possibility of inducing tolerance in nonimmunized adult animals and, consequently, opening up the theoretical possibility of preventing or treating diseases caused by malfunction of the immune system. This strategy has been proven to be useful in the prevention of allergic and autoimmune diseases in rodents, as well as in the amelioration of certain autoimmune diseases in humans. Although there is experimental and clinical evidence for the usefulness of oral tolerance in medical practice, the mechanisms responsible for this phenomenon are still poorly understood, and the results obtained are not always satisfactory. Herein, we show that the thymus is required for the induction and maintenance of oral tolerance, providing evidence that it is not a pure form of clonal deletion-based peripheral tolerance. Oral tolerance could therefore depend on the formation and release to the periphery of regulatory T cells, such as gammadelta or alphabeta T cells, by the thymus. This finding may have profound implications for the treatment of autoimmune diseases, since most of them are associated with thymic hypofunction. On the other hand, due to so far unknown mechanisms, the intraperitoneal co-administration of normal IgG to mice orally treated with tolerogen leads to a sustained and intense immunological tolerance, both in euthymic and thymectomized mice, including those of the lupus erythematosus-prone NZB x NZW lineage. This approach for inducing and maintaining tolerance in thymus-deficient conditions is discussed and put forth herein as a new evidence-based proposition for the therapy of autoimmune diseases.
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Affiliation(s)
- José Mengel
- Department of Immunology, Institute for Biomedical Sciences IV, University of São Paulo, Av. Prof. Lineu Prestes 1730, CEP 05508-900, São Paulo.
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46
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Esashi E, Ito H, Ishihara K, Hirano T, Koyasu S, Miyajima A. Development of CD4+Macrophages from Intrathymic T Cell Progenitors Is Induced by Thymic Epithelial Cells. THE JOURNAL OF IMMUNOLOGY 2004; 173:4360-7. [PMID: 15383565 DOI: 10.4049/jimmunol.173.7.4360] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
It was recently demonstrated that there are CD4(+) macrophages, which exhibit strong phagocytic activity, in the thymus. They are suggested to play an important role for the elimination of apoptotic thymocytes. However, the origin and nature of CD4(+) macrophages in the thymus remain unexplored. In this study, we describe that the most immature intrathymic progenitors (CD25(-)/CD44(+)/FcR(+)) give rise to CD4(+) macrophages by oncostatin M-responsive thymic epithelial cells (ORTEC) in an IL-7-dependent manner. Neither conditioned medium of ORTEC nor a mixture of cytokines induced CD4(+) macrophages, and oncostatin M receptor was not expressed in thymocytes, suggesting that the development of CD4(+) macrophages from the immature thymocytes requires a direct interaction with ORTEC. These results collectively suggest that the development of CD4(+) macrophages from the intrathymic T cell progenitors is induced by thymic epithelial cells.
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Affiliation(s)
- Eiji Esashi
- Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo, Japan
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47
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Scherer A, Noest A, de Boer RJ. Activation-threshold tuning in an affinity model for the T-cell repertoire. Proc Biol Sci 2004; 271:609-16. [PMID: 15156919 PMCID: PMC1691638 DOI: 10.1098/rspb.2003.2653] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Naive T cells respond to peptides from foreign proteins and remain tolerant to self peptides from endogenous proteins. It has been suggested that self tolerance comes about by a 'tuning' mechanism, i.e. by increasing the T-cell activation threshold upon interaction with self peptides. Here, we explore how such an adaptive mechanism of T-cell tolerance would influence the reactivity of the T-cell repertoire to foreign peptides. We develop a computer simulation model in which T cells are tolerized by increasing their activation-threshold dependent on the affinity with which they see self peptides presented in the thymus. Thus, different T cells acquire different activation thresholds (i.e. different cross-reactivities). In previous mathematical models, T-cell tolerance was deletional and based on a fixed cross-reactivity parameter, which was assumed to have evolved to an optimal value. Comparing these two different tolerance-induction mechanisms, we found that the tuning model performs somewhat better than an optimized deletion model in terms of the reactivity to foreign antigens. Thus, evolutionary optimization of clonal cross-reactivity is not required. A straightforward extension of the tuning model is to delete T-cell clones that obtain a too high activation threshold, and to replace these by new clones. The reactivity of the immune repertoires of such a replacement model is enchanced compared with the basic tuning model. These results demonstrate that activation-threshold tuning is a functional mechanism for self tolerance induction.
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Affiliation(s)
- Almut Scherer
- Theoretical Biology/Bioinformatics, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
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48
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van den Berg HA, Rand DA. Dynamics of T cell activation threshold tuning. J Theor Biol 2004; 228:397-416. [PMID: 15135038 DOI: 10.1016/j.jtbi.2004.02.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Revised: 01/23/2004] [Accepted: 02/04/2004] [Indexed: 11/27/2022]
Abstract
T lymphocytes are believed to alter their sensitivity to TCR stimulation by means of a tunable cellular activation threshold. We present two modelling examples which show that the concept of a tunable threshold can be made mechanistically plausible. The tunable threshold is treated as an emergent property of the dynamics of the T cell's signalling machinery. In addition, we discuss how the dynamic properties of activation threshold tuning can be determined experimentally with the aid of these two models. We propose a novel 'avidity selection' mechanism for the initial stages of the immune response, based on the properties of the T cell activation threshold tuning mechanism we propose for the commitment to differentiation. Our main finding is that activation threshold tuning allows T cells to respond to relevant ligands with a detection threshold that is (i) uniform across both the T cell repertoire and the secondary lymphoid tissues, while (ii) retaining tolerance to autostimulation. Our analysis indicates that central tolerance enhances the efficiency of peripheral tolerance, casting new light on the role of negative selection in the thymus.
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Affiliation(s)
- Hugo A van den Berg
- Interdisciplinary Programme for Cellular Regulation Mathematics Institute, University of Warwick, Coventry CV4 7AL, UK.
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49
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Schrum AG, Turka LA, Palmer E. Surface T-cell antigen receptor expression and availability for long-term antigenic signaling. Immunol Rev 2003; 196:7-24. [PMID: 14617194 DOI: 10.1046/j.1600-065x.2003.00083.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
It is important to understand how T-cell antigen receptor (TCR) engagement and signaling are regulated throughout an immune response. This review examines the dynamics of surface TCR expression and signaling capacity during thymic and effector T-cell development. Although the TCR can undergo vast changes in surface expression, T cells remain capable of sustaining TCR engagement for long periods of time. This may be achieved by a combination of mechanisms that involve (a) controlling the quantity of surface TCR available for ligand interaction and (b) controlling the quality of surface TCR expression during T-cell activation. TCR signaling itself appears to be one of the main quantitative modulators of surface TCR expression, and it can cause both downregulation and upregulation at different times of T-cell activation. Recent studies indicate that the degree of upregulation is tunable by the strength of antigenic stimulation. There is evidence that qualitatively distinct forms of the TCR exist, and their potential role in sustained antigenic signaling is also discussed. A goal of future studies will be to better characterize these modulations in surface TCR expression and to clarify their impact on the regulation of immune responses.
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Affiliation(s)
- Adam G Schrum
- Laboratory of Transplantation Immunology and Nephrology, Department of Research, University Hospital-Basel, Hebelstrasse 20, CH-4031 Basel, Switzerland.
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Domínguez-Gerpe L, Rey-Méndez M. Evolution of the thymus size in response to physiological and random events throughout life. Microsc Res Tech 2003; 62:464-76. [PMID: 14635139 DOI: 10.1002/jemt.10408] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
During embryogenesis and in the early stages of life, the thymus is a crucial organ for the generation of the T cell repertoire. T cells are generated from hematopoietic stem cells already differentiated to precursor T cells in the bone marrow. These cells enter the thymus guided by chemotactic factors secreted by this organ. The complex maturation process takes place that ensures self-tolerance and homeostasis. Thymocytes that show autoreactivity do not leave the thymus, but rather die by apoptosis. The final percentage of mature T cells that survive to migrate from the thymus to the periphery is very low: at most 5%, under optimal conditions. The highest migration occurs in childhood and adulthood, at least in mice and humans; however, it declines throughout life and is minimal in the elderly. Under normal circumstances, the thymus commences involution soon after birth, and this involution correlates with the capacity to export mature T cells to the periphery. Hormones, cytokines, and neurotransmitters all play a role in this age-associated process, but the reasons for and mechanisms of this involution remain unknown. Apart from physiological conditions that change throughout life and govern age-related thymus evolution, random states and events provoked by intrinsic or extrinsic factors can induce either thymus involution, as in reversible transient thymic hypoplasias, or thymic hyperplasias. The age-associated involution, unlike transient involutions, follows a regular pattern for all individuals, though there are clear differences between the sexes. Nevertheless, even the age-associated involution seems to be reversible, raising the possibility of therapeutic strategies aimed at enhancing thymus function in the elderly.
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Affiliation(s)
- Lourdes Domínguez-Gerpe
- Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universidad de Santiago de Compostela, 15706 Santiago de Compostela, La Coruña, Spain.
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