1
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Wither MJ, White WL, Pendyala S, Leanza PJ, Fowler DM, Kueh HY. Antigen perception in T cells by long-term Erk and NFAT signaling dynamics. Proc Natl Acad Sci U S A 2023; 120:e2308366120. [PMID: 38113261 PMCID: PMC10756264 DOI: 10.1073/pnas.2308366120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 10/20/2023] [Indexed: 12/21/2023] Open
Abstract
Immune system threat detection hinges on T cells' ability to perceive varying peptide-major histocompatibility complex (pMHC) antigens. As the Erk and NFAT pathways link T cell receptor engagement to gene regulation, their signaling dynamics may convey information about pMHC inputs. To test this idea, we developed a dual reporter mouse strain and a quantitative imaging assay that, together, enable simultaneous monitoring of Erk and NFAT dynamics in live T cells over day-long timescales as they respond to varying pMHC inputs. Both pathways initially activate uniformly across various pMHC inputs but diverge only over longer (9+ h) timescales, enabling independent encoding of pMHC affinity and dose. These late signaling dynamics are decoded via multiple temporal and combinatorial mechanisms to generate pMHC-specific transcriptional responses. Our findings underscore the importance of long timescale signaling dynamics in antigen perception and establish a framework for understanding T cell responses under diverse contexts.
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Affiliation(s)
- Matthew J. Wither
- University of Washington, Department of Bioengineering, Seattle, WA98195
| | - William L. White
- University of Washington, Department of Bioengineering, Seattle, WA98195
| | - Sriram Pendyala
- University of Washington, Department of Genome Sciences, Seattle, WA98195
| | - Paul J. Leanza
- University of Washington, Department of Bioengineering, Seattle, WA98195
| | - Douglas M. Fowler
- University of Washington, Department of Genome Sciences, Seattle, WA98195
| | - Hao Yuan Kueh
- University of Washington, Department of Bioengineering, Seattle, WA98195
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA98109
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2
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Wither MJ, White WL, Pendyala S, Leanza PJ, Fowler D, Kueh HY. Antigen perception in T cells by long-term Erk and NFAT signaling dynamics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.01.543260. [PMID: 37333368 PMCID: PMC10274683 DOI: 10.1101/2023.06.01.543260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Immune system threat detection hinges on T cells' ability to perceive varying peptide major-histocompatibility complex (pMHC) antigens. As the Erk and NFAT pathways link T cell receptor engagement to gene regulation, their signaling dynamics may convey information about pMHC inputs. To test this idea, we developed a dual reporter mouse strain and a quantitative imaging assay that, together, enable simultaneous monitoring of Erk and NFAT dynamics in live T cells over day-long timescales as they respond to varying pMHC inputs. Both pathways initially activate uniformly across various pMHC inputs, but diverge only over longer (9+ hrs) timescales, enabling independent encoding of pMHC affinity and dose. These late signaling dynamics are decoded via multiple temporal and combinatorial mechanisms to generate pMHC-specific transcriptional responses. Our findings underscore the importance of long timescale signaling dynamics in antigen perception, and establish a framework for understanding T cell responses under diverse contexts. SIGNIFICANCE STATEMENT To counter diverse pathogens, T cells mount distinct responses to varying peptide-major histocompatibility complex ligands (pMHCs). They perceive the affinity of pMHCs for the T cell receptor (TCR), which reflects its foreignness, as well as pMHC abundance. By tracking signaling responses in single living cells to different pMHCs, we find that T cells can independently perceive pMHC affinity vs dose, and encode this information through the dynamics of Erk and NFAT signaling pathways downstream of the TCR. These dynamics are jointly decoded by gene regulatory mechanisms to produce pMHC-specific activation responses. Our work reveals how T cells can elicit tailored functional responses to diverse threats and how dysregulation of these responses may lead to immune pathologies.
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3
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Kirby D, Zilman A. Proofreading does not result in more reliable ligand discrimination in receptor signaling due to its inherent stochasticity. Proc Natl Acad Sci U S A 2023; 120:e2212795120. [PMID: 37192165 PMCID: PMC10214210 DOI: 10.1073/pnas.2212795120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 04/05/2023] [Indexed: 05/18/2023] Open
Abstract
Kinetic proofreading (KPR) has been used as a paradigmatic explanation for the high specificity of ligand discrimination by cellular receptors. KPR enhances the difference in the mean receptor occupancy between different ligands compared to a nonproofread receptor, thus potentially enabling better discrimination. On the other hand, proofreading also attenuates the signal and introduces additional stochastic receptor transitions relative to a nonproofreading receptor. This increases the relative magnitude of noise in the downstream signal, which can interfere with reliable ligand discrimination. To understand the effect of noise on ligand discrimination beyond the comparison of the mean signals, we formulate the task of ligand discrimination as a problem of statistical estimation of the receptor affinity of ligands based on the molecular signaling output. Our analysis reveals that proofreading typically worsens ligand resolution compared to a nonproofread receptor. Furthermore, the resolution decreases further with more proofreading steps under most commonly biologically considered conditions. This contrasts with the usual notion that KPR universally improves ligand discrimination with additional proofreading steps. Our results are consistent across a variety of different proofreading schemes and metrics of performance, suggesting that they are inherent to the KPR mechanism itself rather than any particular model of molecular noise. Based on our results, we suggest alternative roles for KPR schemes such as multiplexing and combinatorial encoding in multi-ligand/multi-output pathways.
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Affiliation(s)
- Duncan Kirby
- Department of Physics, University of Toronto, 60 St George St, Toronto, ONM5S 1A7, Canada
| | - Anton Zilman
- Department of Physics, University of Toronto, 60 St George St, Toronto, ONM5S 1A7, Canada
- Institute for Biomedical Engineering, University of Toronto, 164 college St, Toronto, ONM5S 1A7, Canada
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4
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Majumdar S, Lin Y, Bettini ML. Host-microbiota interactions shaping T-cell response and tolerance in type 1 diabetes. Front Immunol 2022; 13:974178. [PMID: 36059452 PMCID: PMC9434376 DOI: 10.3389/fimmu.2022.974178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 07/25/2022] [Indexed: 11/29/2022] Open
Abstract
Type-1 Diabetes (T1D) is a complex polygenic autoimmune disorder involving T-cell driven beta-cell destruction leading to hyperglycemia. There is no cure for T1D and patients rely on exogenous insulin administration for disease management. T1D is associated with specific disease susceptible alleles. However, the predisposition to disease development is not solely predicted by them. This is best exemplified by the observation that a monozygotic twin has just a 35% chance of developing T1D after their twin's diagnosis. This makes a strong case for environmental triggers playing an important role in T1D incidence. Multiple studies indicate that commensal gut microbiota and environmental factors that alter their composition might exacerbate or protect against T1D onset. In this review, we discuss recent literature highlighting microbial species associated with T1D. We explore mechanistic studies which propose how some of these microbial species can modulate adaptive immune responses in T1D, with an emphasis on T-cell responses. We cover topics ranging from gut-thymus and gut-pancreas communication, microbial regulation of peripheral tolerance, to molecular mimicry of islet antigens by microbial peptides. In light of the accumulating evidence on commensal influences in neonatal thymocyte development, we also speculate on the link between molecular mimicry and thymic selection in the context of T1D pathogenesis. Finally, we explore how these observations could inform future therapeutic approaches in this disease.
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Affiliation(s)
- Shubhabrata Majumdar
- Immunology Graduate Program, Baylor College of Medicine, Houston, TX, United States
- Department of Pathology, University of Utah, Salt Lake City, UT, United States
| | - Yong Lin
- Immunology Graduate Program, Baylor College of Medicine, Houston, TX, United States
- Department of Pathology, University of Utah, Salt Lake City, UT, United States
| | - Matthew L. Bettini
- Department of Pathology, University of Utah, Salt Lake City, UT, United States
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5
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Frazer GL, Gawden-Bone CM, Dieckmann NMG, Asano Y, Griffiths GM. Signal strength controls the rate of polarization within CTLs during killing. J Cell Biol 2021; 220:212498. [PMID: 34292303 PMCID: PMC8302442 DOI: 10.1083/jcb.202104093] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/03/2021] [Accepted: 06/30/2021] [Indexed: 01/19/2023] Open
Abstract
Cytotoxic T lymphocytes (CTLs) are key effector cells in the immune response against viruses and cancers, killing targets with high precision. Target cell recognition by CTL triggers rapid polarization of intracellular organelles toward the synapse formed with the target cell, delivering cytolytic granules to the immune synapse. Single amino acid changes within peptides binding MHC class I (pMHCs) are sufficient to modulate the degree of killing, but exactly how this impacts the choreography of centrosome polarization and granule delivery to the target cell remains poorly characterized. Here we use 4D imaging and find that the pathways orchestrating killing within CTL are conserved irrespective of the signal strength. However, the rate of initiation along these pathways varies with signal strength. We find that increased strength of signal leads to an increased proportion of CTLs with prolonged dwell times, initial Ca2+ fluxes, centrosome docking, and granule polarization. Hence, TCR signal strength modulates the rate but not organization of effector CTL responses.
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Affiliation(s)
- Gordon L Frazer
- Cambridge Institute for Medical Research, Biomedical Campus, Cambridge, UK
| | | | - Nele M G Dieckmann
- Cambridge Institute for Medical Research, Biomedical Campus, Cambridge, UK
| | - Yukako Asano
- Cambridge Institute for Medical Research, Biomedical Campus, Cambridge, UK
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6
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Pettmann J, Huhn A, Abu Shah E, Kutuzov MA, Wilson DB, Dustin ML, Davis SJ, van der Merwe PA, Dushek O. The discriminatory power of the T cell receptor. eLife 2021; 10:e67092. [PMID: 34030769 PMCID: PMC8219380 DOI: 10.7554/elife.67092] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 05/15/2021] [Indexed: 12/20/2022] Open
Abstract
T cells use their T cell receptors (TCRs) to discriminate between lower-affinity self and higher-affinity non-self peptides presented on major histocompatibility complex (pMHC) antigens. Although the discriminatory power of the TCR is widely believed to be near-perfect, technical difficulties have hampered efforts to precisely quantify it. Here, we describe a method for measuring very low TCR/pMHC affinities and use it to measure the discriminatory power of the TCR and the factors affecting it. We find that TCR discrimination, although enhanced compared with conventional cell-surface receptors, is imperfect: primary human T cells can respond to pMHC with affinities as low as KD ∼ 1 mM. The kinetic proofreading mechanism fit our data, providing the first estimates of both the time delay (2.8 s) and number of biochemical steps (2.67) that are consistent with the extraordinary sensitivity of antigen recognition. Our findings explain why self pMHC frequently induce autoimmune diseases and anti-tumour responses, and suggest ways to modify TCR discrimination.
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Affiliation(s)
- Johannes Pettmann
- Sir William Dunn School of Pathology, University of OxfordOxfordUnited Kingdom
- Radcliffe Department of Medicine, Medical Research Council Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of OxfordOxfordUnited Kingdom
| | - Anna Huhn
- Sir William Dunn School of Pathology, University of OxfordOxfordUnited Kingdom
| | - Enas Abu Shah
- Sir William Dunn School of Pathology, University of OxfordOxfordUnited Kingdom
- Kennedy Institute of Rheumatology, University of OxfordOxfordUnited Kingdom
| | - Mikhail A Kutuzov
- Sir William Dunn School of Pathology, University of OxfordOxfordUnited Kingdom
| | - Daniel B Wilson
- Sir William Dunn School of Pathology, University of OxfordOxfordUnited Kingdom
- Boston University, Department of Mathematics and StatisticsBostonUnited States
| | - Michael L Dustin
- Kennedy Institute of Rheumatology, University of OxfordOxfordUnited Kingdom
| | - Simon J Davis
- Radcliffe Department of Medicine, Medical Research Council Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of OxfordOxfordUnited Kingdom
| | | | - Omer Dushek
- Sir William Dunn School of Pathology, University of OxfordOxfordUnited Kingdom
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7
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Shen L, Matloubian M, Kadlecek TA, Weiss A. A disease-associated mutation that weakens ZAP70 autoinhibition enhances responses to weak and self-ligands. Sci Signal 2021; 14:14/668/eabc4479. [PMID: 33531381 DOI: 10.1126/scisignal.abc4479] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The cytoplasmic kinase ZAP70 is critical for T cell antigen receptor (TCR) signaling. The R360P mutation in ZAP70 is responsible for an early-onset familial autoimmune syndrome. The structural location and biochemical signaling effects of the R360P mutation are consistent with weakening of the autoinhibitory conformation of ZAP70. Mice with a ZAP70 R360P mutation and polyclonal TCR repertoires exhibited relatively normal T cell development but showed evidence of increased signaling. In addition, the R360P mutation resulted in enhanced follicular helper T cell expansion after LCMV infection. To eliminate the possibility of a TCR repertoire shift, the OTI transgenic TCR was introduced into R360P mice, which resulted in enhanced T cell responses to weaker stimuli, including weak agonists and a self-peptide. These observations suggest that disruption of ZAP70 autoinhibition by the R360P mutation enables increased mature T cell sensitivity to self-antigens that would normally be ignored by wild-type T cells, a mechanism that may contribute to the break of tolerance in human patients with R360P mutation.
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Affiliation(s)
- Lin Shen
- Rosalind Russell and Ephraim P. Engleman Rheumatology Research Center, Division of Rheumatology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Mehrdad Matloubian
- Rosalind Russell and Ephraim P. Engleman Rheumatology Research Center, Division of Rheumatology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Theresa A Kadlecek
- Rosalind Russell and Ephraim P. Engleman Rheumatology Research Center, Division of Rheumatology, University of California, San Francisco, San Francisco, CA 94143, USA.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Arthur Weiss
- Rosalind Russell and Ephraim P. Engleman Rheumatology Research Center, Division of Rheumatology, University of California, San Francisco, San Francisco, CA 94143, USA. .,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94143, USA
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8
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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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9
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Rushdi M, Li K, Yuan Z, Travaglino S, Grakoui A, Zhu C. Mechanotransduction in T Cell Development, Differentiation and Function. Cells 2020; 9:E364. [PMID: 32033255 PMCID: PMC7072571 DOI: 10.3390/cells9020364] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 01/16/2020] [Accepted: 01/17/2020] [Indexed: 02/07/2023] Open
Abstract
Cells in the body are actively engaging with their environments that include both biochemical and biophysical aspects. The process by which cells convert mechanical stimuli from their environment to intracellular biochemical signals is known as mechanotransduction. Exemplifying the reliance on mechanotransduction for their development, differentiation and function are T cells, which are central to adaptive immune responses. T cell mechanoimmunology is an emerging field that studies how T cells sense, respond and adapt to the mechanical cues that they encounter throughout their life cycle. Here we review different stages of the T cell's life cycle where existing studies have shown important effects of mechanical force or matrix stiffness on a T cell as sensed through its surface molecules, including modulating receptor-ligand interactions, inducing protein conformational changes, triggering signal transduction, amplifying antigen discrimination and ensuring directed targeted cell killing. We suggest that including mechanical considerations in the immunological studies of T cells would inform a more holistic understanding of their development, differentiation and function.
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Affiliation(s)
- Muaz Rushdi
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; (M.R.); (K.L.); (S.T.)
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA;
| | - Kaitao Li
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; (M.R.); (K.L.); (S.T.)
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA;
| | - Zhou Yuan
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA;
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30313, USA
| | - Stefano Travaglino
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; (M.R.); (K.L.); (S.T.)
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA;
| | - Arash Grakoui
- Emory Vaccine Center, Division of Microbiology and Immunology, Yerkes Research Primate Center, Emory University School of Medicine, Atlanta, GA 30329, USA;
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Cheng Zhu
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; (M.R.); (K.L.); (S.T.)
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA;
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30313, USA
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10
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Kondo K, Ohigashi I, Takahama Y. Thymus machinery for T-cell selection. Int Immunol 2020; 31:119-125. [PMID: 30476234 DOI: 10.1093/intimm/dxy081] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 11/20/2018] [Indexed: 01/01/2023] Open
Abstract
An immunocompetent and self-tolerant pool of naive T cells is formed in the thymus through the process of repertoire selection. T cells that are potentially capable of responding to foreign antigens are positively selected in the thymic cortex and are further selected in the thymic medulla to help prevent self-reactivity. The affinity between T-cell antigen receptors expressed by newly generated T cells and self-peptide-major histocompatibility complexes displayed in the thymic microenvironments plays a key role in determining the fate of developing T cells during thymic selection. Recent advances in our knowledge of the biology of thymic epithelial cells have revealed unique machinery that contributes to positive and negative selection in the thymus. In this article, we summarize recent findings on thymic T-cell selection, focusing on the machinery unique to thymic epithelial cells.
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Affiliation(s)
- Kenta Kondo
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.,Division of Experimental Immunology, Institute of Advanced Medical Sciences, University of Tokushima, Kuramoto, Tokushima, Japan
| | - Izumi Ohigashi
- Division of Experimental Immunology, Institute of Advanced Medical Sciences, University of Tokushima, Kuramoto, Tokushima, Japan
| | - Yousuke Takahama
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.,Division of Experimental Immunology, Institute of Advanced Medical Sciences, University of Tokushima, Kuramoto, Tokushima, Japan
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11
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Abstract
Thymocyte selection involves the positive and negative selection of the repertoire of T cell receptors (TCRs) such that the organism does not suffer autoimmunity, yet has the benefit of the ability to recognize any invading pathogen. The signal transduced through the TCR is translated into a number of different signaling cascades that result in transcription factor activity in the nucleus and changes to the cytoskeleton and motility. Negative selection involves inducing apoptosis in thymocytes that express strongly self-reactive TCRs, whereas positive selection must induce survival and differentiation programs in cells that are more weakly self-reactive. The TCR recognition event is analog by nature, but the outcome of signaling is not. A large number of molecules regulate the strength of the TCR-derived signal at various points in the cascades. This review discusses the various factors that can regulate the strength of the TCR signal during thymocyte development.
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Affiliation(s)
- Nicholas R J Gascoigne
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, and Immunology Program, National University of Singapore, Singapore 11759;
| | - Vasily Rybakin
- Laboratory of Immunobiology, REGA Institute, Department of Microbiology and Immunology, KU Leuven, Leuven 3000, Belgium
| | - Oreste Acuto
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Joanna Brzostek
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, and Immunology Program, National University of Singapore, Singapore 11759;
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12
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Schmitt TM, Aggen DH, Ishida-Tsubota K, Ochsenreither S, Kranz DM, Greenberg PD. Generation of higher affinity T cell receptors by antigen-driven differentiation of progenitor T cells in vitro. Nat Biotechnol 2017; 35:1188-1195. [PMID: 29106410 PMCID: PMC5722674 DOI: 10.1038/nbt.4004] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 10/13/2017] [Indexed: 01/19/2023]
Abstract
Many promising targets for T-cell-based cancer immunotherapies are self-antigens. During thymic selection, T cells bearing T cell receptors (TCRs) with high affinity for self-antigen are eliminated. The affinity of the remaining low-avidity TCRs can be improved to increase their antitumor efficacy, but conventional saturation mutagenesis approaches are labor intensive, and the resulting TCRs may be cross-reactive. Here we describe the in vitro maturation and selection of mouse and human T cells on antigen-expressing feeder cells to develop higher-affinity TCRs. The approach takes advantage of natural Tcrb gene rearrangement to generate diversity in the length and composition of CDR3β. In vitro differentiation of progenitors transduced with a known Tcra gene in the presence of antigen drives differentiation of cells with a distinct agonist-selected phenotype. We purified these cells to generate TCRβ chain libraries pre-enriched for target antigen specificity. Several TCRβ chains paired with a transgenic TCRα chain to produce a TCR with higher affinity than the parental TCR for target antigen, without evidence of cross-reactivity.
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Affiliation(s)
- Thomas M Schmitt
- Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - David H Aggen
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | | | - Sebastian Ochsenreither
- Department of Hematology, Oncology, and Tumor Immunology, Charité Campus Benjamin Franklin, Berlin, Germany
| | - David M Kranz
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Philip D Greenberg
- Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
- Departments of Immunology and Medicine, University of Washington, Seattle, Washington, USA
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13
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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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14
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Hoyne GF, Elliott H, Mutsaers SE, Prêle CM. Idiopathic pulmonary fibrosis and a role for autoimmunity. Immunol Cell Biol 2017; 95:577-583. [DOI: 10.1038/icb.2017.22] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 02/28/2017] [Accepted: 03/01/2017] [Indexed: 12/11/2022]
Affiliation(s)
- Gerard F Hoyne
- School of Health Sciences, University of Notre Dame Australia Fremantle Western Australia Australia
- Institute of Health Research, University of Notre Dame Fremantle Western Australia Australia
- Centre for Cell Therapy and Regenerative Medicine, School of Medicine and Pharmacology, Harry Perkins Institute of Medical Research, University of Western Australia Nedlands Western Australia Australia
| | - Hannah Elliott
- School of Health Sciences, University of Notre Dame Australia Fremantle Western Australia Australia
- Centre for Cell Therapy and Regenerative Medicine, School of Medicine and Pharmacology, Harry Perkins Institute of Medical Research, University of Western Australia Nedlands Western Australia Australia
| | - Steven E Mutsaers
- Centre for Cell Therapy and Regenerative Medicine, School of Medicine and Pharmacology, Harry Perkins Institute of Medical Research, University of Western Australia Nedlands Western Australia Australia
- Institute for Respiratory Health, Centre for Respiratory Health, School of Medicine and Pharmacology, University of Western Australia Nedlands Western Australia Australia
| | - Cecilia M Prêle
- Centre for Cell Therapy and Regenerative Medicine, School of Medicine and Pharmacology, Harry Perkins Institute of Medical Research, University of Western Australia Nedlands Western Australia Australia
- Institute for Respiratory Health, Centre for Respiratory Health, School of Medicine and Pharmacology, University of Western Australia Nedlands Western Australia Australia
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15
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Kincaid EZ, Murata S, Tanaka K, Rock KL. Specialized proteasome subunits have an essential role in the thymic selection of CD8(+) T cells. Nat Immunol 2016; 17:938-45. [PMID: 27294792 PMCID: PMC4955723 DOI: 10.1038/ni.3480] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 05/02/2016] [Indexed: 12/11/2022]
Abstract
The cells that stimulate positive selection express specialized proteasome β-subunits different from those expressed by all other cells, including those involved in negative selection. Mice that lack all four specialized proteasome β-subunits, and therefore express only constitutive proteasomes in all cells, had a profound defect in the generation of CD8(+) T cells. While a defect in positive selection would reflect an inability to generate the appropriate positively selecting peptides, a block at negative selection would point to the potential need to switch peptides between positive selection and negative selection to avoid the two processes' often cancelling each other out. We found that the block in T cell development occurred around the checkpoints of positive selection and, unexpectedly, negative selection as well.
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Affiliation(s)
- Eleanor Z. Kincaid
- Department of Pathology, University of Massachusetts Medical School, Worcester, MA, U.S.A
| | - Shigeo Murata
- Laboratory of Protein Metabolism, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Keiji Tanaka
- Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Kenneth L. Rock
- Department of Pathology, University of Massachusetts Medical School, Worcester, MA, U.S.A
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16
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The Role of Alternative Splicing in the Control of Immune Homeostasis and Cellular Differentiation. Int J Mol Sci 2015; 17:ijms17010003. [PMID: 26703587 PMCID: PMC4730250 DOI: 10.3390/ijms17010003] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 12/11/2015] [Accepted: 12/15/2015] [Indexed: 12/21/2022] Open
Abstract
Alternative splicing of pre-mRNA helps to enhance the genetic diversity within mammalian cells by increasing the number of protein isoforms that can be generated from one gene product. This provides a great deal of flexibility to the host cell to alter protein function, but when dysregulation in splicing occurs this can have important impact on health and disease. Alternative splicing is widely used in the mammalian immune system to control the development and function of antigen specific lymphocytes. In this review we will examine the splicing of pre-mRNAs yielding key proteins in the immune system that regulate apoptosis, lymphocyte differentiation, activation and homeostasis, and discuss how defects in splicing can contribute to diseases. We will describe how disruption to trans-acting factors, such as heterogeneous nuclear ribonucleoproteins (hnRNPs), can impact on cell survival and differentiation in the immune system.
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17
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Gascoigne NRJ, Acuto O. THEMIS: a critical TCR signal regulator for ligand discrimination. Curr Opin Immunol 2015; 33:86-92. [PMID: 25700024 DOI: 10.1016/j.coi.2015.01.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 01/27/2015] [Accepted: 01/30/2015] [Indexed: 10/24/2022]
Abstract
Genetic approaches identified THEMIS as a critical element driving positive selection of CD4(+)CD8(+) thymocytes towards maturation. THEMIS is expressed only in the T-cell lineage, and is recruited to the proximity of signaling T-cell antigen receptors (TCR) by association with the membrane scaffold LAT. However, its molecular role remained an enigma until recently. Conventionally positively-selected T-cells are lacking in THEMIS-deficient mice, leading to the initial hypothesis that THEMIS positively regulates TCR signaling. Recent data show that THEMIS deficiency increases rather than decreases TCR signaling, leading to augmented apoptosis. The finding that THEMIS is constitutively bound to the tyrosine phosphatases SHP1 or SHP2, provides a mechanism for THEMIS action. When recruited onto LAT, THEMIS-SHP promotes immediate dephosphorylation of TCR-proximal signaling components. This negative feedback is central in setting sharp signaling thresholds and helps explain the exquisite ligand discrimination by the TCR, particularly during thymocyte selection.
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Affiliation(s)
- Nicholas R J Gascoigne
- Department of Microbiology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, 5 Science Drive 2, Singapore 117597, Singapore.
| | - Oreste Acuto
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
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18
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Smith TRF, Verdeil G, Marquardt K, Sherman LA. Contribution of TCR signaling strength to CD8+ T cell peripheral tolerance mechanisms. THE JOURNAL OF IMMUNOLOGY 2014; 193:3409-16. [PMID: 25156361 DOI: 10.4049/jimmunol.1401194] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Peripheral tolerance mechanisms are in place to prevent T cells from mediating aberrant immune responses directed against self and environmental Ags. Mechanisms involved in the induction of peripheral tolerance include T cell-intrinsic pathways, such as anergy or deletion, or exogenous tolerance mediated by regulatory T cells. We have previously shown that the density of peptide-MHC class I recognized by the TCR determines whether CD8(+) T cells undergo anergy or deletion. Specifically, using a TCR-transgenic CD8(+) T cell model, we demonstrated that persistent peripheral exposure to low- or high-dose peptides in the absence of inflammatory signals resulted in clonal deletion or anergy of the T cell, respectively. In this study, by altering the affinity of the peptide-MHC tolerogen for TCR, we have confirmed that this mechanism is dependent on the level of TCR signaling that the CD8(+) T cell receives. Using altered peptide ligands (APLs) displaying high TCR affinities, we show that increasing the TCR signaling favors anergy induction. Conversely, using APLs displaying a decreased TCR affinity tilted our system in the direction of deletional tolerance. We demonstrate how differential peripheral CD8(+) T cell tolerance mechanisms are controlled by both the potency and density of MHC class I-peptide tolerogen.
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Affiliation(s)
- Trevor R F Smith
- Department of Immunology and Microbial Sciences, The Scripps Research Institute, La Jolla, CA 92037
| | - Gregory Verdeil
- Department of Immunology and Microbial Sciences, The Scripps Research Institute, La Jolla, CA 92037
| | - Kristi Marquardt
- Department of Immunology and Microbial Sciences, The Scripps Research Institute, La Jolla, CA 92037
| | - Linda A Sherman
- Department of Immunology and Microbial Sciences, The Scripps Research Institute, La Jolla, CA 92037
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19
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Fu G, Casas J, Rigaud S, Rybakin V, Lambolez F, Brzostek J, Hoerter JAH, Paster W, Acuto O, Cheroutre H, Sauer K, Gascoigne NRJ. Themis sets the signal threshold for positive and negative selection in T-cell development. Nature 2013; 504:441-5. [PMID: 24226767 PMCID: PMC3977001 DOI: 10.1038/nature12718] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 09/26/2013] [Indexed: 12/31/2022]
Abstract
Development of a self-tolerant T-cell receptor (TCR) repertoire with the potential to recognize the universe of infectious agents depends on proper regulation of TCR signalling. The repertoire is whittled down during T-cell development in the thymus by the ability of quasi-randomly generated TCRs to interact with self-peptides presented by major histocompatibility complex (MHC) proteins. Low-affinity TCR interactions with self-MHC proteins generate weak signals that initiate 'positive selection', causing maturation of CD4- or CD8αβ-expressing 'single-positive' thymocytes from CD4(+)CD8αβ(+) 'double-positive' precursors. These develop into mature naive T cells of the secondary lymphoid organs. TCR interaction with high-affinity agonist self-ligands results in 'negative selection' by activation-induced apoptosis or 'agonist selection' of functionally differentiated self-antigen-experienced T cells. Here we show that positive selection is enabled by the ability of the T-cell-specific protein Themis to specifically attenuate TCR signal strength via SHP1 recruitment and activation in response to low- but not high-affinity TCR engagement. Themis acts as an analog-to-digital converter translating graded TCR affinity into clear-cut selection outcome. By dampening mild TCR signals Themis increases the affinity threshold for activation, enabling positive selection of T cells with a naive phenotype in response to low-affinity self-antigens.
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Affiliation(s)
- Guo Fu
- Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Javier Casas
- 1] Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA [2] Department of Microbiology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, 5 Science Drive 2, Singapore 117545 [3]
| | - Stephanie Rigaud
- 1] Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA [2]
| | - Vasily Rybakin
- 1] Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA [2] Department of Microbiology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, 5 Science Drive 2, Singapore 117545 [3]
| | - Florence Lambolez
- Developmental Immunology, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, California 92037, USA
| | - Joanna Brzostek
- 1] Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA [2] Department of Microbiology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, 5 Science Drive 2, Singapore 117545
| | - John A H Hoerter
- Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Wolfgang Paster
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Oreste Acuto
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Hilde Cheroutre
- Developmental Immunology, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, California 92037, USA
| | - Karsten Sauer
- 1] Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA [2] Department of Cell and Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Nicholas R J Gascoigne
- 1] Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA [2] Department of Microbiology, Yong Loo Lin School of Medicine and Immunology Programme, National University of Singapore, 5 Science Drive 2, Singapore 117545
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20
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Abstract
Abstract
The primary consequence of positive selection is to render thymocytes responsive to cytokines and chemokines expressed in the thymic medulla. In the present study, our main objective was to discover which cytokines could support the differentiation of positively selected thymocytes. To this end, we have developed an in vitro model suitable for high-throughput analyses of positive selection and CD8 T-cell differentiation. The model involves coculture of TCRhiCD5intCD69− double-positive (DP) thymocytes with peptide-pulsed OP9 cells and γc-cytokines. We report that IL-4, IL-7, and IL-21 have nonredundant effects on positively selected DP thymocytes. IL-7 signaling phosphorylates STAT5 and ERK; induces Foxo1, Klf2, and S1pr1; and supports the differentiation of classic CD8 T cells. IL-4 activates STAT6 and ERK and supports the differentiation of CD8intPD-L1hiCD44hiEOMES+ innate CD8 T cells. IL-21 is produced by thymic epithelial cells and the IL-21 receptor-α is strongly induced on DP thymocytes undergoing positive selection. IL-21 signaling phosphorylates STAT3 and STAT5, but not ERK, and does not support CD8 T-cell differentiation. However, IL-21 has a unique ability to up-regulate BCL-6, expand DP thymocytes undergoing positive selection, and increase the production of mature T cells. Our data suggest that injection of recombinant IL-21 might enhance thymic output in subjects with age- or disease-related thymic atrophy.
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21
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Abstract
Understanding the thymic processes that support the generation of functionally competent and self-tolerant lymphocytes requires dissection of the T-cell receptor (TCR) response to ligands of different affinities. In spatially segregated regions of the thymus, with unique expression of proteases and cytokines, TCR affinity guides a number of cell fate decisions. Yet affinity alone does not explain the selection paradox. Increasing evidence suggests that the 'altered peptide' model of the 1980s together with the affinity model might best explain how the thymus supports conventional and regulatory T-cell development. Development of new tools to study the strength of TCR signals perceived by T cells, novel regulatory T-cell transgenic mice, and tetramer enrichment strategies have provided an insight into the nature of TCR signals perceived during thymocyte development. These topics are discussed and support for the prevailing hypotheses is presented.
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Affiliation(s)
- Amy E Moran
- Center for Immunology, University of Minnesota, Minneapolis, MN 55414, USA
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22
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How the TCR balances sensitivity and specificity for the recognition of self and pathogens. Nat Immunol 2012; 13:121-8. [PMID: 22261968 DOI: 10.1038/ni.2190] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The T cell repertoire is generated during thymic development in preparation for the response to antigens from pathogens. The T cell repertoire is shaped by positive selection, which requires recognition by the T cell antigen receptor (TCR) of complexes of self peptide and major histocompatibility complex proteins (self-pMHC) with low affinity, and negative selection, which eliminates T cells with TCRs that recognize self-pMHC with high affinity. This generates a repertoire with low affinity for self-pMHC but high affinity for foreign antigens. The TCR must successfully engage both of these ligands for development, homeostasis and immune responses. This review discusses mechanisms underlying the interaction of the TCR with peptide-major histocompatibility complex ligands of varying affinity and highlights signaling mechanisms that enable the TCR to generate different responses to very distinct ligands.
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23
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Denton AE, Wesselingh R, Gras S, Guillonneau C, Olson MR, Mintern JD, Zeng W, Jackson DC, Rossjohn J, Hodgkin PD, Doherty PC, Turner SJ. Affinity thresholds for naive CD8+ CTL activation by peptides and engineered influenza A viruses. THE JOURNAL OF IMMUNOLOGY 2011; 187:5733-44. [PMID: 22039305 DOI: 10.4049/jimmunol.1003937] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
High-avidity interactions between TCRs and peptide + class I MHC (pMHCI) epitopes drive CTL activation and expansion. Intriguing questions remain concerning the constraints determining optimal TCR/pMHCI binding. The present analysis uses the TCR transgenic OT-I model to assess how varying profiles of TCR/pMHCI avidity influence naive CTL proliferation and the acquisition of effector function following exposure to the cognate H-2K(b)/OVA(257-264) (SIINFEKL) epitope and to mutants provided as peptide or in engineered influenza A viruses. Stimulating naive OT-I CD8(+) T cells in vitro with SIINFEKL induced full CTL proliferation and differentiation that was largely independent of any need for costimulation. By contrast, in vitro activation with the low-affinity EIINFEKL or SIIGFEKL ligands depended on the provision of IL-2 and other costimulatory signals. Importantly, although they did generate potent endogenous responses, infection of mice with influenza A viruses expressing these same OVA(257) variants failed to induce the activation of adoptively transferred naive OT-I CTLps, an effect that was only partially overcome by priming with a lipopeptide vaccine. Subsequent structural and biophysical analysis of H2-K(b)OVA(257), H2-K(b)E1, and H2-K(b)G4 established that these variations introduce small changes at the pMHCI interface and decrease epitope stability in ways that would likely impact cell surface presentation and recognition. Overall, it seems that there is an activation threshold for naive CTLps, that minimal alterations in peptide sequence can have profound effects, and that the antigenic requirements for the in vitro and in vivo induction of CTL proliferation and effector function differ substantially.
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Affiliation(s)
- Alice E Denton
- Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria 3010, Australia
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24
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Gascoigne NRJ, Palmer E. Signaling in thymic selection. Curr Opin Immunol 2011; 23:207-12. [PMID: 21242076 DOI: 10.1016/j.coi.2010.12.017] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 12/26/2010] [Indexed: 01/22/2023]
Abstract
T cell receptor signaling allows the developing thymocyte to undergo positive or negative selection, which is required for the formation of a useful mature T cell repertoire. Recent developments include the finding that much of the Lck kinase (required to initiate T cell signaling) is already in an active configuration before signaling. The analog strength of antigen binding to the T cell receptor binding may be translated into a digital signal by the amount of time the TCR is paired with a co-receptor carrying Lck. Downstream, the cellular localization of MAP kinase signaling is determined by the strength of the signal and in turn predicts positive or negative selection. A novel protein, Themis, is important in crossing the positive selection developmental checkpoint, but its mode of action is still uncertain. Commitment to the CD4 or CD8 lineage is influenced by the amount of ZAP-70 signaling and also by closely regulated responsiveness to intrathymic cytokines such as IL7.
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Affiliation(s)
- Nicholas R J Gascoigne
- Department of Immunology and Microbial Science, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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25
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Juang J, Ebert PJR, Feng D, Garcia KC, Krogsgaard M, Davis MM. Peptide-MHC heterodimers show that thymic positive selection requires a more restricted set of self-peptides than negative selection. ACTA ACUST UNITED AC 2010; 207:1223-34. [PMID: 20457759 PMCID: PMC2882826 DOI: 10.1084/jem.20092170] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
T cell selection and maturation in the thymus depends on the interactions between T cell receptors (TCRs) and different self-peptide-major histocompatibility complex (pMHC) molecules. We show that the affinity of the OT-I TCR for its endogenous positively selecting ligands, Catnb-H-2Kb and Cappa1-H-2Kb, is significantly lower than for previously reported positively selecting altered peptide ligands. To understand how these extremely weak endogenous ligands produce signals in maturing thymocytes, we generated soluble monomeric and dimeric peptide-H-2Kb ligands. Soluble monomeric ovalbumin (OVA)-Kb molecules elicited no detectable signaling in OT-I thymocytes, whereas heterodimers of OVA-Kb paired with positively selecting or nonselecting endogenous peptides, but not an engineered null peptide, induced deletion. In contrast, dimer-induced positive selection was much more sensitive to the identity of the partner peptide. Catnb-Kb-Catnb-Kb homodimers, but not heterodimers of Catnb-Kb paired with a nonselecting peptide-Kb, induced positive selection, even though both ligands bind the OT-I TCR with detectable affinity. Thus, both positive and negative selection can be driven by dimeric but not monomeric ligands. In addition, positive selection has much more stringent requirements for the partner self-pMHC.
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Affiliation(s)
- Jeremy Juang
- The Department of Microbiology and Immunology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
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26
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Ebert PJR, Li QJ, Huppa JB, Davis MM. Functional development of the T cell receptor for antigen. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2010; 92:65-100. [PMID: 20800817 PMCID: PMC4887107 DOI: 10.1016/s1877-1173(10)92004-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
For over three decades now, the T cell receptor (TCR) for antigen has not ceased to challenge the imaginations of cellular and molecular immunologists alike. T cell antigen recognition transcends every aspect of adaptive immunity: it shapes the T cell repertoire in the thymus and directs T cell-mediated effector functions in the periphery, where it is also central to the induction of peripheral tolerance. Yet, despite its central position, there remain many questions unresolved: how can one TCR be specific for one particular peptide-major histocompatibility complex (pMHC) ligand while also binding other pMHC ligands with an immunologically relevant affinity? And how can a T cell's extreme specificity (alterations of single methyl groups in their ligand can abrogate a response) and sensitivity (single agonist ligands on a cell surface are sufficient to trigger a measurable response) emerge from TCR-ligand interactions that are so low in affinity? Solving these questions is intimately tied to a fundamental understanding of molecular recognition dynamics within the many different contexts of various T cell-antigen presenting cell (APC) contacts: from the thymic APCs that shape the TCR repertoire and guide functional differentiation of developing T cells to the peripheral APCs that support homeostasis and provoke antigen responses in naïve, effector, memory, and regulatory T cells. Here, we discuss our recent findings relating to T cell antigen recognition and how this leads to the thymic development of foreign-antigen-responsive alphabetaT cells.
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Affiliation(s)
- Peter J R Ebert
- The Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
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27
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Abstract
The healthy immune system makes use of a variety of surveillance mechanisms at different stages of lymphoid development to prevent the occurrence and expansion of potentially harmful autoreactive T cell clones. Disruption of these mechanisms may lead to inappropriate activation of T cells and the development of autoimmune and lymphoproliferative diseases [such as multiple sclerosis, rheumatoid arthritis, lupus erythematosus, diabetes and autoimmune lymphoproliferative syndrome (ALPS)]. Clonal deletion of T cells with high affinities for self-peptide-MHC via programmed cell death (apoptosis) is an essential mechanism leading to self-tolerance. Referred to as negative selection, central tolerance in the thymus serves as the first checkpoint for the developing T cell repertoire and involves the apoptotic elimination of potentially autoreactive T cells clones bearing high affinity T cell receptors (TCR) that recognize autoantigens presented by thymic epithelial cells. Autoreactive T cells that escape negative selection are held in check in the periphery by either functional inactivation ("anergy") or extrathymic clonal deletion, both of which are dependent on the strength and frequency of the TCR signal and the costimulatory context, or by regulatory T cells. This review provides an overview of the different molecular executioners of cell death programs that are vital to intrathymic or extrathymic clonal deletion of T cells. Further, the potential involvement of various apoptotic signaling paradigms are discussed with respect to the genesis and pathophysiology of autoimmune disease.
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Affiliation(s)
- Martina Gatzka
- Department of Molecular Biology and Biochemistry, Center for Immunology, University of California, Irvine, CA, USA.
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28
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Palmer E, Naeher D. Affinity threshold for thymic selection through a T-cell receptor–co-receptor zipper. Nat Rev Immunol 2009; 9:207-13. [DOI: 10.1038/nri2469] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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29
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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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30
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Usharauli D, Kamala T. Brief antigenic stimulation generates effector CD8 T cells with low cytotoxic activity and high IL-2 production. THE JOURNAL OF IMMUNOLOGY 2008; 180:4507-13. [PMID: 18354172 DOI: 10.4049/jimmunol.180.7.4507] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
It is currently believed that a brief antigenic stimulation is sufficient to induce CD8 T cells to complete their differentiation program, become effector T cells, and subsequently generate memory. Because this concept was derived from studies in which only a single effector function was analyzed (either IFN-gamma production or target cell lysis), we wondered whether monitoring for multiple effector functions might reveal novel characteristics of effector CD8 T cells elicited by brief or prolonged Ag exposure. Using an in vitro system to generate effector T cells and an in vivo adoptive transfer model to track donor CD8 T cells, we found that the differentiation programs acquired by CD8 T cells after brief or prolonged antigenic stimulation were different. Although the frequencies of IFN-gamma and TNF-alpha producers were comparable for both effector CD8 T cell populations, there were major differences in cytotoxic potential and IL-2 production. Whereas prolonged (>24 h) Ag exposure stimulated effector CD8 T cells with high cytotoxic activity and low IL-2 production, brief (<24 h) stimulation generated effector CD8 T cells with low cytotoxic activity and high IL-2 production. The latter effector T cells rapidly converted into central memory-like CD8 T cells, exhibited long-term survival in adoptively transferred hosts, and gave robust recall responses upon Ag challenge. These data suggest that not all functions of effector CD8 T cells are equally inherited after brief or prolonged antigenic stimulation.
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Affiliation(s)
- David Usharauli
- T Cell Tolerance and Memory Section (Ghost Lab), Laboratory of Cellular and Molecular Immunology, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892, USA.
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31
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Yachi PP, Ampudia J, Zal T, Gascoigne NRJ. Altered Peptide Ligands Induce Delayed CD8-T Cell Receptor Interaction—a Role for CD8 in Distinguishing Antigen Quality. Immunity 2006; 25:203-11. [PMID: 16872849 DOI: 10.1016/j.immuni.2006.05.015] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Revised: 04/21/2006] [Accepted: 05/11/2006] [Indexed: 10/24/2022]
Abstract
How T cells translate T cell receptor (TCR) recognition of almost identical pMHC ligands into distinct biological responses has remained enigmatic. Although differences in affinity or off rate are important, they offer at best an incomplete explanation. By using Förster resonance energy transfer (FRET), we have visualized the ligand-induced interaction between OT-I TCR and CD8. We found that both recruitment of TCR to the immunological synapse and the TCR-CD8 interaction induced by weak agonists (positive-selecting ligands) was delayed but not necessarily weaker than strong agonists (negative selectors). A delayed and perhaps longer lasting CD8-TCR interaction results in delayed phospho-ERK recruitment to the synapse. The kinetics of the TCR-CD8 interaction can reconcile previously anomalous data, where biological activity did not correlate with TCR-pMHC binding kinetics for certain ligands. Our findings indicate that the T cell translates antigen recognition into T cell responses by differential recruitment of CD8 to the TCR.
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Affiliation(s)
- Pia P Yachi
- Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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32
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Holst J, Vignali KM, Burton AR, Vignali DAA. Rapid analysis of T-cell selection in vivo using T cell-receptor retrogenic mice. Nat Methods 2006; 3:191-7. [PMID: 16489336 DOI: 10.1038/nmeth858] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2005] [Accepted: 01/20/2006] [Indexed: 01/09/2023]
Abstract
Although T-cell receptor (TCR) transgenic as well as knockout and knockin mice have had a large impact on our understanding of T-cell development, signal transduction and function, the need to cross these mice delays experiments considerably. Here we provide a methodology for the rapid expression of TCRs in mice using 2A peptide-linked multicistronic retroviral vectors to transduce stem cells of any background before adoptive transfer into RAG-1(-/-) mice. For simplicity, we refer to these as retrogenic mice. We demonstrate that these retrogenic mice are comparable to transgenic mice expressing three commonly used TCRs (OT-I, OT-II [corrected] and AND). We also show that retrogenic mice expressing male antigen-specific TCRs (HY, MataHari and Marilyn) facilitated the analysis of positive and negative selection in female and male mice, respectively. We examined various tolerance mechanisms in epitope-coupled TCR retrogenic mice. This powerful resource could expedite the identification of proteins involved in T-cell development and function.
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Affiliation(s)
- Jeff Holst
- Department of Immunology, St. Jude Children's Research Hospital, 332 N. Lauderdale, Memphis, Tennessee 38105, USA
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33
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Vukmanović S, Santori FR. Self-peptide/MHC and TCR antagonism: physiological role and therapeutic potential. Cell Immunol 2005; 233:75-84. [PMID: 15950208 DOI: 10.1016/j.cellimm.2005.04.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Accepted: 04/21/2005] [Indexed: 10/25/2022]
Abstract
TCR antagonists are peptides that bind MHC molecules and can specifically inhibit T cell activation induced by antigens. Studying TCR antagonism has taken an important place in immunology for both theoretical and practical reasons. Deciphering the mechanism(s) of action of TCR antagonists can yield important information about interactions of the TCR with ligands, T cell development, and TCR signaling. Moreover, microorganisms may employ TCR antagonism to elude the attention of the immune system. Finally, specificity of inhibition makes TCR antagonists an ideal tool to seek antigen-specific immunomodulation. Present state of knowledge on these topics is reviewed.
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Affiliation(s)
- Stanislav Vukmanović
- Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010-2970, USA.
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34
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Bagchi AK, Sinha AK. Phosphotidylinositol-3 kinase-mediated signals in mice immunized with the 57 kDa major antigenic outer-membrane protein of Shigella dysenteriae type 1. J Med Microbiol 2005; 54:631-637. [PMID: 15947427 DOI: 10.1099/jmm.0.46014-0] [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] [Indexed: 11/18/2022] Open
Abstract
Antigen-specific T-cell signalling via T-cell antigen receptor stimulation was carried out in BALB/c mice immunized with the 57 kDa major antigenic component of Shigella dysenteriae 1 outer-membrane proteins. In presence of anti-CD3, the 57 kDa antigen was found to increase the level of IL-2 significantly instead of IL-4. IL-2 production in T cells was consistent with an increase in intracellular free Ca(2+) [(Ca(2+))i] concentration. The antigen-specific modulation was observed during T-cell signalling, with enhanced release of [(Ca(2+))i]. IL-2-receptor stimulation via IL-2 did not significantly induce the release of IL-2 with consistent intracellular Ca(2+) production. Furthermore, the protein tyrosine kinase was activated during anti-CD3 stimulation, which up-regulated the phosphatidylinositol kinase of p85-mediated serine kinase protein kinase-C of p70. Phosphoinositide-specific kinases are regulated by the phosphorylation of tyrosine kinase through the activation of the T-cell antigen receptor. The above findings indicate that phosphotidylinositol-3 kinase-mediated signals are up-regulated through [(Ca(2+))i], which is essential for Th1-type responses.
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Affiliation(s)
- A K Bagchi
- Division of Immunology and Vaccine Development, National Institute of Cholera & Enteric Diseases, P-33, CIT Road, Scheme: XM, Kolkata 700010, India
| | - A K Sinha
- Division of Immunology and Vaccine Development, National Institute of Cholera & Enteric Diseases, P-33, CIT Road, Scheme: XM, Kolkata 700010, India
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35
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Rubin RL, Hermanson TM. Plasticity in the positive selection of T cells: affinity of the selecting antigen and IL-7 affect T cell responsiveness. Int Immunol 2005; 17:959-71. [PMID: 15994177 DOI: 10.1093/intimm/dxh277] [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: 01/16/2023] Open
Abstract
The current study examines how responsiveness of T cells is affected by the avidity of the peptide/MHC engaged during positive selection of their thymocyte precursors. We used a thymus reaggregate culture system in which CD4(+)CD8(+) thymocytes from AND TCR transgenic mice were induced to undergo positive selection by pigeon cytochrome c (PCC) peptide or its analogs presented by I-E(k) class II MHC on a thymic epithelial cell line. When low-affinity peptide analogs drove positive selection, up to 100 microM was needed to produce >50% CD4(+) T cells, and these cells were highly responsive to PCC. In contrast, <0.2 microM high-affinity peptides was required to achieve similar selection efficiency, but the resultant cells failed to respond to PCC. However, these cells were not dead based on dye exclusion and capacity to respond to phorbal ester and to agonist if IL-2 was also present, supporting the view that non-responsiveness of cells selected on high-affinity peptides is a form of central T cell tolerance distinct from deletion. Cells selected on intermediate-affinity peptides showed variable responsiveness which was suppressed 5- to 10-fold by addition during reaggregate culture of antibody to the IL-7R. Similarly, supplementary IL-7 in the reaggregate culture produced CD4(+) T cells that were promiscuously responsive. Overall, this study demonstrates that the responsiveness of T cells is not rigidly controlled and that the presence of IL-7 during T cell development has the potential to negate central T cell tolerance and produce autoreactive T cells.
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Affiliation(s)
- Robert L Rubin
- Department of Molecular Genetics and Microbiology, MSC08 4660, 1 University of New Mexico Medical School, Albuquerque, NM 87131, USA.
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36
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Kao H, Allen PM. An antagonist peptide mediates positive selection and CD4 lineage commitment of MHC class II-restricted T cells in the absence of CD4. ACTA ACUST UNITED AC 2005; 201:149-58. [PMID: 15630142 PMCID: PMC2212763 DOI: 10.1084/jem.20041574] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The CD4 coreceptor works together with the T cell receptor (TCR) to deliver signals to the developing thymocyte, yet its specific contribution to positive selection and CD4 lineage commitment remains unclear. To resolve this, we used N3.L2 TCR transgenic, RAG-, and CD4-deficient mice, which are severely impaired in positive selection, and asked whether altered peptide ligands can replace CD4 function in vivo. Remarkably, in the presence of antagonist ligands that normally deleted CD4+ T cells in wild-type mice, we induced positive selection of functional CD4 lineage T cells in mice deficient in CD4. We show that the kinetic threshold for positive and negative selection was lowered in the absence of CD4, with no evident skewing toward the CD8 lineage with weaker ligands. These results suggest that CD4 is dispensable as long as the affinity threshold for positive selection is sustained, and strongly argue that CD4 does not deliver a unique instructional signal for lineage commitment.
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Affiliation(s)
- Henry Kao
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
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37
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Risueño RM, Gil D, Fernández E, Sánchez-Madrid F, Alarcón B. Ligand-induced conformational change in the T-cell receptor associated with productive immune synapses. Blood 2005; 106:601-8. [PMID: 15790785 DOI: 10.1182/blood-2004-12-4763] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Triggering of the T-cell receptor (TCR) can produce very different responses, depending on the nature of the major histocompatibility complex/antigen peptide (MHCp) ligand. The molecular mechanisms that permit such fine discrimination are still unknown. We show here that an epitope in the cytoplasmic tail of the TCR CD3epsilon subunit, recognized by antibody APA1/1, is only detected when the TCR is fully activated. Exposure of the APA1/1 epitope is shown to be fast and independent of tyrosine kinase activity and that it takes place even when T cells are stimulated at 0 degrees C. These results suggest that APA1/1 detects a conformational change in the TCR. APA1/1 staining concentrates in a restricted area of the immunologic synapse. Most important, we show that full agonist, but not partial agonist, peptides induce exposure of the APA1/1 epitope, indicating a correlation between the induction of the conformational change in the TCR and full T-cell activation. Finally, the conformational change is shown to occur in T cells that are being stimulated by antigen in vivo. Therefore, these results demonstrate that the TCR undergoes a conformational change on MHCp binding in vitro and in vivo, and they establish a molecular correlate for productive TCR engagement.
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Affiliation(s)
- Ruth M Risueño
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco Madrid 28049, Spain
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38
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Baldwin TA, Hogquist KA, Jameson SC. The fourth way? Harnessing aggressive tendencies in the thymus. THE JOURNAL OF IMMUNOLOGY 2005; 173:6515-20. [PMID: 15557139 DOI: 10.4049/jimmunol.173.11.6515] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
During late stages of thymic development, T cells must chose between different fates, dictated by their TCR specificity. Typically, this is thought of as a choice between three alternatives (being positive selection for useful T cells vs negative selection or neglect for harmful or useless T cells). However, there is growing evidence for a fourth alternative, in which T cells are positively selected by agonist ligands, which would normally be expected to induce T cell deletion. In this review, we will discuss where and when agonist selection is induced and whether this should be considered as a novel form of thymic selection or as an alternative differentiation state for Ag-exposed T cells.
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Affiliation(s)
- Troy A Baldwin
- Center for Immunology, Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA
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39
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Santori FR, Holmberg K, Ostrov D, Gascoigne NRJ, Vukmanović S. Distinct footprints of TCR engagement with highly homologous ligands. THE JOURNAL OF IMMUNOLOGY 2004; 172:7466-75. [PMID: 15187125 DOI: 10.4049/jimmunol.172.12.7466] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
T cell receptor engagement promotes proliferation, differentiation, survival, or death of T lymphocytes. The affinity/avidity of the TCR ligand and the maturational stage of the T cell are thought to be principal determinants of the outcome of TCR engagement. We demonstrate in this study that the same mouse TCR preferentially uses distinct residues of homologous peptides presented by the MHC molecules to promote specific cellular responses. The preference for distinct TCR contacts depends on neither the affinity/avidity of TCR engagement (except in the most extreme ranges), nor the maturity of engaged T cells. Thus, different portions of the TCR ligand appear capable of biasing T cells toward specific biological responses. These findings explain differences in functional versatility of TCR ligands, as well as anomalies in the relationship between affinity/avidity of the TCR for the peptide/MHC and cellular responses of T cells.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigen Presentation
- Epitope Mapping
- Epitopes, T-Lymphocyte/chemistry
- Epitopes, T-Lymphocyte/physiology
- Ligands
- Mice
- Mice, Transgenic
- Models, Molecular
- Peptides/chemical synthesis
- Peptides/immunology
- Protein Binding
- Protein Footprinting
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell/physiology
- Structure-Activity Relationship
- T-Lymphocyte Subsets
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Affiliation(s)
- Fabio R Santori
- Michael Heidelberger Division of Immunology, Department of Pathology and New York University Cancer Center, New York University School of Medicine, New York, NY 10016, USA
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40
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Walsh CM, Luhrs KA, Arechiga AF. The "fuzzy logic" of the death-inducing signaling complex in lymphocytes. J Clin Immunol 2004; 23:333-53. [PMID: 14601642 DOI: 10.1023/a:1025313415487] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Receptors belonging to the tumor necrosis factor receptor family have long been thought to play an important role in the regulation of immunity. Although this family is composed of a large number of surface receptors that potentiate myriad functions in vivo, a subset is known to directly convey apoptotic signals. One such molecule belonging to this subset is CD95. Ligation of CD95 instigates the formation of a complex known as the "death-inducing signaling complex" or DISC, which is composed of molecules including FADD (Fas associated with death domain) and RIP (receptor-interacting kinase), as well as procaspases-8 and -10, and a caspase-8-like molecule that lacks proteolytic activity called c-FLIP. Although the DISC was initially thought to serve an exclusively proapoptotic role, humans and mice with defects in various components of this complex demonstrate a variety of developmental and hematopoietic defects that are not apparently due to aberrant apoptosis. These findings paint a far more complex picture of the numerous components of the DISC, and provide evidence that these complexes serve nonapoptotic functions. Herein, we summarize the experimental evidence challenging the notion that the DISC imparts an exclusively apoptotic function and provide hypotheses to account for these alternative roles. Rather than operating as a binary system, we propose that the DISCs formed around various DRs transduce signals leading to a variety of cellular fates.
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Affiliation(s)
- Craig M Walsh
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, USA.
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41
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Yamagata T, Mathis D, Benoist C. Self-reactivity in thymic double-positive cells commits cells to a CD8αα lineage with characteristics of innate immune cells. Nat Immunol 2004; 5:597-605. [PMID: 15133507 DOI: 10.1038/ni1070] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2003] [Accepted: 03/15/2004] [Indexed: 12/22/2022]
Abstract
Thymocytes displaying self-reactive T cell receptors usually undergo negative selection in the thymus. Here we demonstrate that agonist peptides can promote positive selection of immature double-positive thymocytes into distinct lineages, varying with the agonist concentration and the animal's age. Microarray gene expression analyses showed broad transcriptional alterations in a set of transcripts associated with the innate immune system, as well as silencing of CD8 beta expression. The resulting CD8 alpha alpha T cells showed a rapid effector cytokine response. Hence, T cells displaying self-reactive receptors can have the gene expression profile and phenotypic characteristics of innate immune cells.
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Affiliation(s)
- Tetsuya Yamagata
- Section on Immunology and Immunogenetics, Joslin Diabetes Center; Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, One Joslin Place, Boston, Massachusetts 02215, USA
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42
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Cohn M. An alternative to current thinking about positive selection, negative selection and activation of T cells. Immunology 2004; 111:375-80. [PMID: 15056372 PMCID: PMC1782432 DOI: 10.1111/j.0019-2805.2004.01830.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Given that recognition by the T-cell receptor (TCR) of allele-specific determinants on major histocompatibility complex (MHC)-encoded restricting elements (Rs) is germline encoded, whereas recognition of peptide (P) is somatically encoded, two combining site repertoires, anti-R and anti-P, are implied. As a consequence, the three pathways of T cells, positive selection, negative selection and activation, must be signalled by qualitatively distinct interactions engaging the TCR. These are spelled out as they provide an alternative to the current thinking that these pathways depend on affinity-based quantitatively distinguishable interactions.
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Affiliation(s)
- Melvin Cohn
- The Salk Institute for Biological Studies, Conceptual Immunology Group, La Jolla, CA 92037-1099, USA.
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43
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Holman PO, Walsh ER, Hogquist KA. The central tolerance response to male antigen in normal mice is deletion and not receptor editing. THE JOURNAL OF IMMUNOLOGY 2004; 171:4048-53. [PMID: 14530325 DOI: 10.4049/jimmunol.171.8.4048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
It is widely accepted that developing T cells can undergo clonal deletion in the thymus in response to a high affinity self-Ag. This is largely based on studies of TCR transgenics. However, encounter with high affinity self-Ag can also result in receptor editing in TCR transgenic models. Because all TCR transgenics display ectopic receptor expression, the tolerance mechanism that predominates in normal mice remains an open question. When self-Ag drives receptor editing during T cell development, one expects to find in-frame, self-reactive TCRalpha joins on TCR excision circles (TRECs), which are the products of secondary V/J recombination in the TCRalpha locus. Such joins are not expected if clonal deletion occurs, because the progenitor cell would be eliminated by apoptosis. To test the relative utilization of receptor editing vs clonal deletion, we determined the frequency of in-frame, male-specific joins on TRECs in male and female HYbeta transgenic mice. In comparison with female HYbeta transgenic mice, our analysis showed a lower frequency of TRECs with male-reactive V17J57 joins in male mice. Thus, it would appear that receptor editing is not a predominant tolerance mechanism for this self-Ag.
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MESH Headings
- Animals
- Clonal Deletion/genetics
- Female
- Gene Rearrangement, alpha-Chain T-Cell Antigen Receptor
- Gene Rearrangement, beta-Chain T-Cell Antigen Receptor
- H-Y Antigen/genetics
- H-Y Antigen/immunology
- Immune Tolerance/genetics
- Lymph Nodes/cytology
- Lymph Nodes/immunology
- Lymph Nodes/metabolism
- Male
- Mice
- Mice, Knockout
- Mice, Transgenic
- RNA Editing/immunology
- Receptors, Antigen, T-Cell, alpha-beta/biosynthesis
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Transgenes/immunology
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Affiliation(s)
- Philmore O Holman
- Department of Laboratory Medicine and Pathology and Center for Immunology, University of Minnesota, Minneapolis, MN 55455, USA
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44
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Mintern JD, Maurice MM, Ploegh HL, Schott E. Thymic Selection and Peripheral Activation of CD8 T Cells by the Same Class I MHC/Peptide Complex. THE JOURNAL OF IMMUNOLOGY 2003; 172:699-708. [PMID: 14688383 DOI: 10.4049/jimmunol.172.1.699] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Thymic selection is controlled by the interaction between TCR and MHC/peptide. Strength and quality of the signal determine whether thymocytes are selected or deleted. The factors that contribute to this signal remain poorly defined. Here we show that fetal thymic organ cultures (FTOCs) derived from OT-I transgenic mice (the OT-I TCR is restricted by K(b)-SIINFEKL) on a K(b)D(b-/-) background support positive selection, but only when provided with soluble H-2K(b)-SIINFEKL complexes. Selection of CD8 T cells is independent of the valency of the ligand or its capability to coengage CD8 molecules. Both CD8alphaalpha and CD8alphabeta T cells are selected by H-2K(b)-SIINFEKL, but only CD8alphabeta cells are capable of releasing IFN-gamma in response to the same ligand. The alpha(4)beta(7) integrin is up-regulated on postselection thymocytes from FTOCs. After adoptive transfer, FTOC-derived OT-I CD8 T cells divide in response to the agonist peptide SIINFEKL. These results establish that CD8 T cells responsive to their nominal peptide-Ag can be generated in FTOC supplemented with soluble MHC class I molecules equipped with the same peptide.
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Affiliation(s)
- Justine D Mintern
- Department of Pathology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115
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45
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Abstract
A functional immune system requires the selection of T lymphocytes expressing receptors that are major histocompatibility complex restricted but tolerant to self-antigens. This selection occurs predominantly in the thymus, where lymphocyte precursors first assemble a surface receptor. In this review we summarize the current state of the field regarding the natural ligands and molecular factors required for positive and negative selection and discuss a model for how these disparate outcomes can be signaled via the same receptor. We also discuss emerging data on the selection of regulatory T cells. Such cells require a high-affinity interaction with self-antigens, yet differentiate into regulatory cells instead of being eliminated.
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Affiliation(s)
- Timothy K Starr
- Center for Immunology and the Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis 55455, USA.
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46
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Abstract
Dead cells are a prominent feature of the thymic landscape as only 5% of developing thymocytes are exported as mature T cells. The remaining thymocytes die by one of two mechanisms; most thymocytes die because they are not positively selected and do not receive a survival signal, whereas a minority of thymocytes undergo T-cell receptor (TCR)-mediated apoptosis, a process known as negative selection. Negative selection is extremely important for establishing a functional immune system, as it provides an efficient mechanism for ridding the T-cell repertoire of self-reactive and potentially autoimmune lymphocytes. This review discusses several cellular and molecular aspects of negative selection.
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Affiliation(s)
- Ed Palmer
- Laboratory of Transplantation Immunology and Nephrology, University Hospital Basel, Hebelstrasse 20, CH-4031 Basel, Switzerland.
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47
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Werlen G, Hausmann B, Naeher D, Palmer E. Signaling life and death in the thymus: timing is everything. Science 2003; 299:1859-63. [PMID: 12649474 DOI: 10.1126/science.1067833] [Citation(s) in RCA: 200] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
T lymphocytes are generated in the thymus, where developing thymocytes must accept one of two fates: They either differentiate or they die. These fates are chiefly determined by signals that originate from the T cell receptor (TCR), a single receptor complex with a remarkable capacity to decide between distinct cell fates. This review explores TCR signaling in thymocytes and focuses on the kinetic aspects of ligand binding, coreceptor involvement, protein phosphorylation, and mitogen-activated protein kinase (MAPK) activation. Understanding the logic of TCR signaling may eventually explain how thymocytes and T cells distinguish self from nonself, a phenomenon that has fascinated immunologists for 50 years.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Antigens/immunology
- Antigens, CD/immunology
- Antigens, CD/metabolism
- Apoptosis
- Carrier Proteins/metabolism
- Cell Differentiation
- Cell Division
- Enzyme Activation
- Humans
- Ligands
- MAP Kinase Signaling System
- Major Histocompatibility Complex/immunology
- Membrane Proteins
- Mitogen-Activated Protein Kinases/metabolism
- Phosphoproteins/metabolism
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Receptors, Antigen, T-Cell, alpha-beta/physiology
- Selection, Genetic
- Self Tolerance
- Signal Transduction
- T-Lymphocytes/immunology
- T-Lymphocytes/physiology
- Thymus Gland/cytology
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Affiliation(s)
- Guy Werlen
- Laboratory of Transplantation Immunology and Nephrology, Department of Research, University Hospital-Basel, CH-4031 Basel, Switzerland.
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48
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Hori Y, Raychaudhuri S, Chakraborty AK. Analysis of pattern formation and phase separation in the immunological synapse. J Chem Phys 2002. [DOI: 10.1063/1.1512642] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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49
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Lee SJE, Hori Y, Groves JT, Dustin ML, Chakraborty AK. Correlation of a dynamic model for immunological synapse formation with effector functions: two pathways to synapse formation. Trends Immunol 2002; 23:492-9. [PMID: 12297421 DOI: 10.1016/s1471-4906(02)02285-8] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
During antigen recognition by T cells different receptors and ligands form a pattern in the intercellular junction called the immunological synapse, which might be involved in T-cell activation. Recently, a synapse assembly model has been proposed, which enables the calculation of the propensity for synapse assembly driven by membrane-constrained protein binding interactions. We bring together model predictions of mature synapse assembly with data on the dependence of T-cell responses on T-cell receptor (TCR)-MHC-peptide (pMHC) binding kinetics. Predictions of mature synapse assembly, based on TCR-pMHC binding kinetics, correlate well with observed cytokine responses by T cells bearing the relevant TCR but not with cytotoxic T lymphocyte-mediated killing. We discuss the suggested different role for the synapse in pre- and post-nuclear activation events in T cells. The view of immunological synapse assembly given here emphasizes the importance of both the on and off rates for the TCR-pMHC interaction and in this context recent data on a positive role for analogs of self-peptides in synapse assembly is considered.
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Affiliation(s)
- Sung-Joo E Lee
- Biophysics Graduate Group, Dept of Chemistry, University of California, Berkeley, CA, USA
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Wang B, Sharma A, Maile R, Saad M, Collins EJ, Frelinger JA. Peptidic termini play a significant role in TCR recognition. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:3137-45. [PMID: 12218131 DOI: 10.4049/jimmunol.169.6.3137] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
TCR recognition of class I MHC is dependent on the composition of the antigenic peptide and the MHC. Single amino acid substitutions in either the MHC or the peptide may dramatically alter recognition. While the major interactions between TCR and the peptide/MHC complex appear to be focused on the complementarity-determining region (CDR)3, it is also clear from the cocrystal structure of class I MHC and TCR that the amino and carboxyl ends of the peptide may play a role through interactions with the CDR1. In this work we show that gp33 variants substituted at the peptidic termini at the putative CDR1 contact regions show improved recognition in B6 mice. The rank order of recognition is different using the P14 transgenic T cells, suggesting that one reason for improved recognition is a change in the TCR repertoire that recognizes the peptide. However, the affinity of the TCR by some of the peptide/MHC complex with increased recognition is improved, as shown by increased tetramer binding to P14 T cells. These substitutions at the termini of the peptide-binding cleft cause localized conformational changes as seen by changes in mAb binding and crystallographic structures. The different peptide structures also show different conformations in the center of the peptide, but these are shown to be energetically similar and thus most likely have no significance with respect to TCR recognition. Therefore, small conformational changes, localized to the CDR1 contact regions, may play a significant role in TCR recognition.
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MESH Headings
- Amino Acid Substitution/genetics
- Amino Acid Substitution/immunology
- Animals
- Antigens, Viral/immunology
- Antigens, Viral/metabolism
- CD8-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/metabolism
- Cells, Cultured
- Cytotoxicity Tests, Immunologic
- Glycoproteins/immunology
- Glycoproteins/metabolism
- H-2 Antigens/immunology
- H-2 Antigens/metabolism
- Histocompatibility Antigen H-2D
- Lymphocytic choriomeningitis virus/immunology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Oligopeptides/immunology
- Oligopeptides/metabolism
- Oligopeptides/physiology
- Peptide Fragments/immunology
- Peptide Fragments/metabolism
- Protein Binding/immunology
- Protein Conformation
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/metabolism
- Viral Proteins/immunology
- Viral Proteins/metabolism
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Affiliation(s)
- Bo Wang
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599, USA
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