1
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Wilhelm KB, Vissa A, Groves JT. Differential roles of kinetic on- and off-rates in T-cell receptor signal integration revealed with a modified Fab'-DNA ligand. Proc Natl Acad Sci U S A 2024; 121:e2406680121. [PMID: 39298491 PMCID: PMC11441509 DOI: 10.1073/pnas.2406680121] [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: 04/02/2024] [Accepted: 08/05/2024] [Indexed: 09/21/2024] Open
Abstract
Antibody-derived T-cell receptor (TCR) agonists are commonly used to activate T cells. While antibodies can trigger TCRs regardless of clonotype, they bypass native T cell signal integration mechanisms that rely on monovalent, membrane-associated, and relatively weakly binding ligand in the context of cellular adhesion. Commonly used antibodies and their derivatives bind much more strongly than native peptide major histocompatibility complex (pMHC) ligands bind their cognate TCRs. Because ligand dwell time is a critical parameter that tightly correlates with physiological function of the TCR signaling system, there is a general need, both in research and therapeutics, for universal TCR ligands with controlled kinetic binding parameters. To this end, we have introduced point mutations into recombinantly expressed α-TCRβ H57 Fab to modulate the dwell time of monovalent Fab binding to TCR. When tethered to a supported lipid bilayer via DNA complementation, these monovalent Fab'-DNA ligands activate T cells with potencies well-correlated with their TCR binding dwell time. Single-molecule tracking studies in live T cells reveal that individual binding events between Fab'-DNA ligands and TCRs elicit local signaling responses closely resembling native pMHC. The unique combination of high on- and off-rates of the H57 R97L mutant enables direct observations of cooperative interplay between ligand binding and TCR-proximal condensation of the linker for activation of T cells, which is not readily visualized with pMHC. This work provides insights into how T cells integrate kinetic information from TCR ligands and introduces a method to develop affinity panels for polyclonal T cells, such as cells from a human patient.
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MESH Headings
- Humans
- Kinetics
- Ligands
- Signal Transduction
- Immunoglobulin Fab Fragments/metabolism
- Immunoglobulin Fab Fragments/immunology
- Immunoglobulin Fab Fragments/chemistry
- Immunoglobulin Fab Fragments/genetics
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- DNA/metabolism
- Receptors, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell/immunology
- Protein Binding
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Lymphocyte Activation
- Point Mutation
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Affiliation(s)
- Kiera B. Wilhelm
- Department of Chemistry, University of California-Berkeley, Berkeley, CA94720
| | - Anand Vissa
- Department of Chemistry, University of California-Berkeley, Berkeley, CA94720
| | - Jay T. Groves
- Department of Chemistry, University of California-Berkeley, Berkeley, CA94720
- Division of Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA94720
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2
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Zhang Y, Liang J, Zhu XH, Lü JL, Jing XJ, Jiang SL, Shen Y, Wang WF, Kuang HX, Xia YG. Reversible ON- and OFF-switch receptors Clec4G and Rab1A reveal the hormetic effects of a pectin polysaccharide in Aralia elata (Miq.) Seem. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2024; 132:155792. [PMID: 39059090 DOI: 10.1016/j.phymed.2024.155792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 05/04/2024] [Accepted: 05/29/2024] [Indexed: 07/28/2024]
Abstract
BACKGROUND Numerous studies indicate that natural polysaccharides have immune-enhancing effects as a host defense potentiator. Few reports are available on hormetic effects of natural polysaccharides, and the underlying mechanisms remain unclear. PURPOSE AELP-B6 (arabinose- and galactose-rich pectin polysaccharide) from Aralia elata (Miq.) Seem was taken as a case study to clarify the potential mechanism of hormetic effects of natural polysaccharides. METHODS The pharmacodynamic effect of AELP-B6 was verified by constructing the CTX-immunosuppressive mouse model. The hormetic effects were explored by TMT-labeled proteomics, energy metabolism analysis, flow cytometry and western blot. The core-affinity target of AELP-B6 was determined by pull down, nanoLC-nanoESI+-MS, CETSA, immunoblot and SPR assay. The RAW264.7Clec4G-RFP and RAW264.7Rab1A-RFP cell lines were simultaneously constructed to determine the affinity difference between AELP-B6 and targets by confocal laser scanning live-cell imaging. Antibody blocking assays were further used to verify the mechanism of hormetic effects. RESULTS AELP-B6 at low and medium doses may maintain the structural integrity of thymus and spleen, increase the concentrations of TNF-α, IFN-γ, IL-3 and IL-8, and alleviate CTX-induced reduction of immune cell viability in vivo. Proteomics and energy metabolism analysis revealed that AELP-B6 regulate HIF-1α-mediated metabolic programming, causing Warburg effects in macrophages. AELP-B6 at low and medium doses promoted the release of intracellular immune factors, and driving M1-like polarization of macrophages. As a contrast, AELP-B6 at high dose enhanced the expression levels of apoptosis related proteins, indicating activation of the intrinsic apoptotic cascade. Two highly expressed transmembrane proteins in macrophages, Clec4G and Rab1A, were identified as the primary binding targets of AELP-B6 which co-localized with the cell membrane and directly impacted with immune cell activation and apoptosis. AELP-B6 exhibits affinity differences with Clec4G and Rab1A, which is the key to the hormetic effects. CONCLUSION We observed hormesis of natural polysaccharide (AELP-B6) for the first time, and AELP-B6 mediates the hormetic effects through two dose-related targets. Low dose of AELP-B6 targets Clec4G, thereby driving the M1-like polarization via regulating NF-κB signaling pathway and HIF-1α-mediated metabolic programming, whereas high dose of AELP-B6 targets Rab1A, leading to mitochondria-dependent apoptosis.
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Affiliation(s)
- Yi Zhang
- Key Laboratory of Basic and Application Research of Beiyao (Heilongjiang University of Chinese Medicine), Ministry of Education, 24 Heping Road, Harbin 150040, PR China
| | - Jun Liang
- Key Laboratory of Basic and Application Research of Beiyao (Heilongjiang University of Chinese Medicine), Ministry of Education, 24 Heping Road, Harbin 150040, PR China
| | - Xin-Hua Zhu
- Key Laboratory of Basic and Application Research of Beiyao (Heilongjiang University of Chinese Medicine), Ministry of Education, 24 Heping Road, Harbin 150040, PR China
| | - Jia-Lu Lü
- Key Laboratory of Basic and Application Research of Beiyao (Heilongjiang University of Chinese Medicine), Ministry of Education, 24 Heping Road, Harbin 150040, PR China
| | - Xiao-Jie Jing
- Key Laboratory of Basic and Application Research of Beiyao (Heilongjiang University of Chinese Medicine), Ministry of Education, 24 Heping Road, Harbin 150040, PR China
| | - Si-Liang Jiang
- Key Laboratory of Basic and Application Research of Beiyao (Heilongjiang University of Chinese Medicine), Ministry of Education, 24 Heping Road, Harbin 150040, PR China
| | - Yu Shen
- College of Pharmacy, Jiamusi University, 258 Xuefu Street, Jiamusi 154007, PR China
| | - Wen-Fei Wang
- Bio-pharmaceutical Lab, College of Life Sciences, Northeast Agricultural University, Harbin 150030, PR China
| | - Hai-Xue Kuang
- Key Laboratory of Basic and Application Research of Beiyao (Heilongjiang University of Chinese Medicine), Ministry of Education, 24 Heping Road, Harbin 150040, PR China
| | - Yong-Gang Xia
- Key Laboratory of Basic and Application Research of Beiyao (Heilongjiang University of Chinese Medicine), Ministry of Education, 24 Heping Road, Harbin 150040, PR China.
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3
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Hiratsuka H, Akahori Y, Maeta S, Egashira Y, Shiku H. Fast on-rates of chimeric antigen receptors enhance the sensitivity to peptide MHC via antigen rebinding. J Biol Chem 2024; 300:107651. [PMID: 39122001 PMCID: PMC11407991 DOI: 10.1016/j.jbc.2024.107651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2024] [Accepted: 07/30/2024] [Indexed: 08/12/2024] Open
Abstract
Chimeric antigen receptor (CAR) is a synthetic receptor that induces T cell-mediated lysis of abnormal cells. As cancer driver proteins are present at low levels on the cell surface, they can cause weak CAR reactivity, resulting in antigen sensitivity defects and consequently limited therapeutic efficacy. Although affinity maturation enhances the efficacy of CAR-T cell therapy, it causes off-target cross-reactions resulting in adverse effects. Preferentially expressed antigen in melanoma (PRAME) is an intracellular oncoprotein that is overexpressed in various tumors and restricted in normal tissues, except the testis. Therefore, PRAME could be an ideal target for cancer immunotherapy. In this study, we developed an experimental CAR system comprising six single-chain variable fragments that specifically recognizes the PRAMEp301/HLA-A∗24:02 complex. Cell-mediated cytotoxicity was demonstrated using a panel of CARs with a wide range of affinities (KD = 10-10-10-7 M) and affinity modulation. CAR-T cells with fast on-rates enhance antigen sensitivity by accelerating the killing rates of these cells. Alanine scanning data demonstrated the potential of genetically engineered CARs to reduce the risk of cross-reactivity, even among CARs with high affinities. Given the correlation between on-rates and dwell time that occurs in rebinding and cell-mediated cytotoxicity, it is proposed that CAR-binding characteristics, including on-rate, play a pivotal role in the lytic capacity of peptide-major histocompatibility complex-targeting CAR-T cells, thus facilitating the development of strategies whereby genetically engineered CARs target intracellular antigens in cancer cells to lyse the cells.
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Affiliation(s)
- Hiroyuki Hiratsuka
- Department of Personalized Cancer Immunotherapy, Graduate School of Medicine, Mie University, Tsu, Mie, Japan.
| | - Yasushi Akahori
- Department of Personalized Cancer Immunotherapy, Graduate School of Medicine, Mie University, Tsu, Mie, Japan.
| | - Shingo Maeta
- Bio-Diagnostic Reagent Technology Center, Sysmex Corporation, Kobe, Hyogo, Japan
| | - Yuriko Egashira
- Bio-Diagnostic Reagent Technology Center, Sysmex Corporation, Kobe, Hyogo, Japan
| | - Hiroshi Shiku
- Department of Personalized Cancer Immunotherapy, Graduate School of Medicine, Mie University, Tsu, Mie, Japan; Center for Comprehensive Cancer Immunotherapy, Mie University, Tsu, Mie, Japan
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4
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Schrangl L, Mühlgrabner V, Platzer R, Kellner F, Wieland J, Obst R, Toca-Herrera JL, Huppa JB, Schütz GJ, Göhring J. Advanced Quantification of Receptor-Ligand Interaction Lifetimes via Single-Molecule FRET Microscopy. Biomolecules 2024; 14:1001. [PMID: 39199389 PMCID: PMC11352576 DOI: 10.3390/biom14081001] [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: 06/28/2024] [Revised: 08/05/2024] [Accepted: 08/07/2024] [Indexed: 09/01/2024] Open
Abstract
Receptor-ligand interactions at cell interfaces initiate signaling cascades essential for cellular communication and effector functions. Specifically, T cell receptor (TCR) interactions with pathogen-derived peptides presented by the major histocompatibility complex (pMHC) molecules on antigen-presenting cells are crucial for T cell activation. The binding duration, or dwell time, of TCR-pMHC interactions correlates with downstream signaling efficacy, with strong agonists exhibiting longer lifetimes compared to weak agonists. Traditional surface plasmon resonance (SPR) methods quantify 3D affinity but lack cellular context and fail to account for factors like membrane fluctuations. In the recent years, single-molecule Förster resonance energy transfer (smFRET) has been applied to measure 2D binding kinetics of TCR-pMHC interactions in a cellular context. Here, we introduce a rigorous mathematical model based on survival analysis to determine exponentially distributed receptor-ligand interaction lifetimes, verified through simulated data. Additionally, we developed a comprehensive analysis pipeline to extract interaction lifetimes from raw microscopy images, demonstrating the model's accuracy and robustness across multiple TCR-pMHC pairs. Our new software suite automates data processing to enhance throughput and reduce bias. This methodology provides a refined tool for investigating T cell activation mechanisms, offering insights into immune response modulation.
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Affiliation(s)
- Lukas Schrangl
- Institute of Biophysics, Department of Bionanosciences, University of Natural Resources and Life Sciences, Muthgasse 11, 1190 Vienna, Austria; (L.S.)
- Institute of Applied Physics, TU Wien, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria
| | - Vanessa Mühlgrabner
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, 1090 Vienna, Austria
| | - René Platzer
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, 1090 Vienna, Austria
| | - Florian Kellner
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, 1090 Vienna, Austria
| | - Josephine Wieland
- Institute for Immunology, Biomedical Center, Medical Faculty, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany
| | - Reinhard Obst
- Institute for Immunology, Biomedical Center, Medical Faculty, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany
| | - José L. Toca-Herrera
- Institute of Biophysics, Department of Bionanosciences, University of Natural Resources and Life Sciences, Muthgasse 11, 1190 Vienna, Austria; (L.S.)
| | - Johannes B. Huppa
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, 1090 Vienna, Austria
| | - Gerhard J. Schütz
- Institute of Applied Physics, TU Wien, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria
| | - Janett Göhring
- Institute for Hygiene and Applied Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Lazarettgasse 19, 1090 Vienna, Austria
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5
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Rogers J, Bajur AT, Salaita K, Spillane KM. Mechanical control of antigen detection and discrimination by T and B cell receptors. Biophys J 2024; 123:2234-2255. [PMID: 38794795 PMCID: PMC11331051 DOI: 10.1016/j.bpj.2024.05.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 05/10/2024] [Accepted: 05/21/2024] [Indexed: 05/26/2024] Open
Abstract
The adaptive immune response is orchestrated by just two cell types, T cells and B cells. Both cells possess the remarkable ability to recognize virtually any antigen through their respective antigen receptors-the T cell receptor (TCR) and B cell receptor (BCR). Despite extensive investigations into the biochemical signaling events triggered by antigen recognition in these cells, our ability to predict or control the outcome of T and B cell activation remains elusive. This challenge is compounded by the sensitivity of T and B cells to the biophysical properties of antigens and the cells presenting them-a phenomenon we are just beginning to understand. Recent insights underscore the central role of mechanical forces in this process, governing the conformation, signaling activity, and spatial organization of TCRs and BCRs within the cell membrane, ultimately eliciting distinct cellular responses. Traditionally, T cells and B cells have been studied independently, with researchers working in parallel to decipher the mechanisms of activation. While these investigations have unveiled many overlaps in how these cell types sense and respond to antigens, notable differences exist. To fully grasp their biology and harness it for therapeutic purposes, these distinctions must be considered. This review compares and contrasts the TCR and BCR, placing emphasis on the role of mechanical force in regulating the activity of both receptors to shape cellular and humoral adaptive immune responses.
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Affiliation(s)
- Jhordan Rogers
- Department of Chemistry, Emory University, Atlanta, Georgia
| | - Anna T Bajur
- Department of Physics, King's College London, London, United Kingdom; Randall Centre for Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Khalid Salaita
- Department of Chemistry, Emory University, Atlanta, Georgia; Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia.
| | - Katelyn M Spillane
- Department of Physics, King's College London, London, United Kingdom; Randall Centre for Cell and Molecular Biophysics, King's College London, London, United Kingdom; Department of Life Sciences, Imperial College London, London, United Kingdom.
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6
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Shi J, Yin W, Chen W. Mathematical models of TCR initial triggering. Front Immunol 2024; 15:1411614. [PMID: 39091495 PMCID: PMC11291225 DOI: 10.3389/fimmu.2024.1411614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 07/05/2024] [Indexed: 08/04/2024] Open
Abstract
T cell receptors (TCRs) play crucial roles in regulating T cell response by rapidly and accurately recognizing foreign and non-self antigens. The process involves multiple molecules and regulatory mechanisms, forming a complex network to achieve effective antigen recognition. Mathematical modeling techniques can help unravel the intricate network of TCR signaling and identify key regulators that govern it. In this review, we introduce and briefly discuss relevant mathematical models of TCR initial triggering, with a focus on kinetic proofreading (KPR) models with different modified structures. We compare the topology structures, biological hypotheses, parameter choices, and simulation performance of each model, and summarize the advantages and limitations of them. Further studies on TCR modeling design, aiming for an optimized balance of specificity and sensitivity, are expected to contribute to the development of new therapeutic strategies.
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Affiliation(s)
- Jiawei Shi
- Department of Cardiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- Key Laboratory for Biomedical Engineering of the Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China
| | - Weiwei Yin
- Department of Cardiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China
| | - Wei Chen
- Department of Cardiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- Key Laboratory for Biomedical Engineering of the Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China
- Department of Cell Biology, School of Medicine, Zhejiang University, Hangzhou, China
- Liangzhu Laboratory, Zhejiang University, Hangzhou, China
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7
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Wilhelm KB, Vissa A, Groves JT. Differential Roles of Kinetic On- and Off-Rates in T-Cell Receptor Signal Integration Revealed with a Modified Fab'-DNA Ligand. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.01.587588. [PMID: 38617215 PMCID: PMC11014569 DOI: 10.1101/2024.04.01.587588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Antibody-derived T-cell receptor (TCR) agonists are commonly used to activate T cells. While antibodies can trigger TCRs regardless of clonotype, they bypass native T cell signal integration mechanisms that rely on monovalent, membrane-associated, and relatively weakly-binding ligand in the context of cellular adhesion. Commonly used antibodies and their derivatives bind much more strongly than native peptide-MHC (pMHC) ligands bind their cognate TCRs. Because ligand dwell time is a critical parameter that tightly correlates with physiological function of the TCR signaling system, there is a general need, both in research and therapeutics, for universal TCR ligands with controlled kinetic binding parameters. To this end, we have introduced point mutations into recombinantly expressed α-TCRβ H57 Fab to modulate the dwell time of monovalent Fab binding to TCR. When tethered to a supported lipid bilayer via DNA complementation, these monovalent Fab'-DNA ligands activate T cells with potencies well-correlated with their TCR binding dwell time. Single-molecule tracking studies in live T cells reveal that individual binding events between Fab'-DNA ligands and TCRs elicit local signaling responses closely resembling native pMHC. The unique combination of high on- and off-rate of the H57 R97L mutant enables direct observations of cooperative interplay between ligand binding and TCR-proximal condensation of the linker for activation of T cells (LAT), which is not readily visualized with pMHC. This work provides insights into how T cells integrate kinetic information from synthetic ligands and introduces a method to develop affinity panels for polyclonal T cells, such as cells from a human patient.
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Affiliation(s)
- Kiera B Wilhelm
- Department of Chemistry, University of California-Berkeley, Berkeley, CA, 93720
| | - Anand Vissa
- Department of Chemistry, University of California-Berkeley, Berkeley, CA, 93720
| | - Jay T Groves
- Department of Chemistry, University of California-Berkeley, Berkeley, CA, 93720
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8
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Rogers J, Ma R, Foote A, Hu Y, Salaita K. Force-Induced Site-Specific Enzymatic Cleavage Probes Reveal That Serial Mechanical Engagement Boosts T Cell Activation. J Am Chem Soc 2024; 146:7233-7242. [PMID: 38451498 PMCID: PMC10958510 DOI: 10.1021/jacs.3c08137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 03/08/2024]
Abstract
The T cell membrane is studded with >104 T cell receptors (TCRs) that are used to scan target cells to identify short peptide fragments associated with viral infection or cancerous mutation. These peptides are presented as peptide-major-histocompatibility complexes (pMHCs) on the surface of virtually all nucleated cells. The TCR-pMHC complex forms at cell-cell junctions, is highly transient, and experiences mechanical forces. An important question in this area pertains to the role of the force duration in immune activation. Herein, we report the development of force probes that autonomously terminate tension within a time window following mechanical triggering. Force-induced site-specific enzymatic cleavage (FUSE) probes tune the tension duration by controlling the rate of a force-triggered endonuclease hydrolysis reaction. This new capability provides a method to study how the accumulated force duration contributes to T cell activation. We screened DNA sequences and identified FUSE probes that disrupt mechanical interactions with F > 7.1 piconewtons (pN) between TCRs and pMHCs. This rate of disruption, or force lifetime (τF), is tunable from tens of minutes down to 1.9 min. T cells challenged with FUSE probes with F > 7.1 pN presenting cognate antigens showed up to a 23% decrease in markers of early activation. FUSE probes with F > 17.0 pN showed weaker influence on T cell triggering further showing that TCR-pMHC with F > 17.0 pN are less frequent compared to F > 7.1 pN. Taken together, FUSE probes allow a new strategy to investigate the role of force dynamics in mechanotransduction broadly and specifically suggest a model of serial mechanical engagement boosting TCR activation.
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Affiliation(s)
- Jhordan Rogers
- Department
of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - Rong Ma
- Department
of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - Alexander Foote
- Department
of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - Yuesong Hu
- Department
of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
| | - Khalid Salaita
- Department
of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States
- Wallace
H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332, United States
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9
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Acuto O. T-cell virtuosity in ''knowing thyself". Front Immunol 2024; 15:1343575. [PMID: 38415261 PMCID: PMC10896960 DOI: 10.3389/fimmu.2024.1343575] [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: 11/23/2023] [Accepted: 01/17/2024] [Indexed: 02/29/2024] Open
Abstract
Major Histocompatibility Complex (MHC) I and II and the αβ T-cell antigen receptor (TCRαβ) govern fundamental traits of adaptive immunity. They form a membrane-borne ligand-receptor system weighing host proteome integrity to detect contamination by nonself proteins. MHC-I and -II exhibit the "MHC-fold", which is able to bind a large assortment of short peptides as proxies for self and nonself proteins. The ensuing varying surfaces are mandatory ligands for Ig-like TCRαβ highly mutable binding sites. Conserved molecular signatures guide TCRαβ ligand binding sites to focus on the MHC-fold (MHC-restriction) while leaving many opportunities for its most hypervariable determinants to contact the peptide. This riveting molecular strategy affords many options for binding energy compatible with specific recognition and signalling aimed to eradicated microbial pathogens and cancer cells. While the molecular foundations of αβ T-cell adaptive immunity are largely understood, uncertainty persists on how peptide-MHC binding induces the TCRαβ signals that instruct cell-fate decisions. Solving this mystery is another milestone for understanding αβ T-cells' self/nonself discrimination. Recent developments revealing the innermost links between TCRαβ structural dynamics and signalling modality should help dissipate this long-sought-after enigma.
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Affiliation(s)
- Oreste Acuto
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
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10
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Borowska MT, Boughter CT, Bunker JJ, Guthmiller JJ, Wilson PC, Roux B, Bendelac A, Adams EJ. Biochemical and biophysical characterization of natural polyreactivity in antibodies. Cell Rep 2023; 42:113190. [PMID: 37804505 PMCID: PMC10858392 DOI: 10.1016/j.celrep.2023.113190] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 08/25/2023] [Accepted: 09/14/2023] [Indexed: 10/09/2023] Open
Abstract
To become specialized binders, antibodies undergo a process called affinity maturation to maximize their binding affinity. Despite this process, some antibodies retain low-affinity binding to diverse epitopes in a phenomenon called polyreactivity. Here we seek to understand the molecular basis of this polyreactivity in antibodies. Our results highlight that polyreactive antigen-binding fragments (Fabs) bind their targets with low affinities, comparable to T cell receptor recognition of autologous classical major histocompatibility complex. Extensive mutagenic studies find no singular amino acid residue or biochemical property responsible for polyreactive interaction, suggesting that polyreactive antibodies use multiple strategies for engagement. Finally, our crystal structures and all-atom molecular dynamics simulations of polyreactive Fabs show increased rigidity compared to their monoreactive relatives, forming a neutral and accessible platform for diverse antigens to bind. Together, these data support a cooperative strategy of rigid neutrality in establishing the polyreactive status of an antibody molecule.
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Affiliation(s)
- Marta T Borowska
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | | | - Jeffrey J Bunker
- Committee on Immunology, University of Chicago, Chicago, IL 60637, USA; Department of Pathology, University of Chicago, Chicago, IL 60637, USA
| | - Jenna J Guthmiller
- Department of Medicine, Section of Rheumatology, University of Chicago, Chicago, IL 60637, USA
| | - Patrick C Wilson
- Committee on Immunology, University of Chicago, Chicago, IL 60637, USA; Department of Medicine, Section of Rheumatology, University of Chicago, Chicago, IL 60637, USA
| | - Benoit Roux
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Albert Bendelac
- Committee on Immunology, University of Chicago, Chicago, IL 60637, USA; Department of Pathology, University of Chicago, Chicago, IL 60637, USA
| | - Erin J Adams
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA; Committee on Immunology, University of Chicago, Chicago, IL 60637, USA.
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11
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Rogers J, Ma R, Hu Y, Salaita K. Force-induced site-specific enzymatic cleavage probes reveal that serial mechanical engagement boosts T cell activation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.07.552310. [PMID: 37609308 PMCID: PMC10441320 DOI: 10.1101/2023.08.07.552310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
The surface of T cells is studded with T cell receptors (TCRs) that are used to scan target cells to identify peptide-major histocompatibility complexes (pMHCs) signatures of viral infection or cancerous mutation. It is now established that the TCR-pMHC complex is highly transient and experiences mechanical forces that augment the fidelity of T cell activation. An important question in this area pertains to the role of force duration in immune activation. Herein, we report the development of force probes that autonomously terminate tension within a time window following mechanical triggering. Force-induced site-specific enzymatic cleavage (FUSE) probes tune tension duration by controlling the rate of a force-triggered endonuclease hydrolysis reaction. This new capability provides a method to study how accumulated force duration contributes to T cell activation. We screened DNA sequences and identified FUSE probes that disrupt mechanical interactions with F >7.1 piconewtons (pN) between TCRs and pMHCs. Force lifetimes (τF) are tunable from tens of min down to 1.9 min. T cells challenged with FUSE probes presenting cognate antigens with τF of 1.9 min demonstrated dampened markers of early activation, thus demonstrating that repeated mechanical sampling boosts TCR activation. Repeated mechanical sampling F >7.1 pN was found to be particularly critical at lower pMHC antigen densities, wherein the T cell activation declined by 23% with τF of 1.9 min. FUSE probes with F >17.0 pN response showed weaker influence on T cell triggering further showing that TCR-pMHC with F >17.0 pN are less frequent compared to F >7.1 pN. Taken together, FUSE probes allow a new strategy to investigate the role of force dynamics in mechanotransduction broadly and specifically suggest a model of serial mechanical engagement in antigen recognition.
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Affiliation(s)
- Jhordan Rogers
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia, 30322, USA
| | - Rong Ma
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia, 30322, USA
| | - Yuesong Hu
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia, 30322, USA
| | - Khalid Salaita
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia, 30322, USA
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, 30332, USA
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12
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Morgan J, Lindsay AE. Modulation of antigen discrimination by duration of immune contacts in a kinetic proofreading model of T cell activation with extreme statistics. PLoS Comput Biol 2023; 19:e1011216. [PMID: 37647345 PMCID: PMC10497171 DOI: 10.1371/journal.pcbi.1011216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 09/12/2023] [Accepted: 08/05/2023] [Indexed: 09/01/2023] Open
Abstract
T cells form transient cell-to-cell contacts with antigen presenting cells (APCs) to facilitate surface interrogation by membrane bound T cell receptors (TCRs). Upon recognition of molecular signatures (antigen) of pathogen, T cells may initiate an adaptive immune response. The duration of the T cell/APC contact is observed to vary widely, yet it is unclear what constructive role, if any, such variations might play in immune signaling. Modeling efforts describing antigen discrimination often focus on steady-state approximations and do not account for the transient nature of cellular contacts. Within the framework of a kinetic proofreading (KP) mechanism, we develop a stochastic First Receptor Activation Model (FRAM) describing the likelihood that a productive immune signal is produced before the expiry of the contact. Through the use of extreme statistics, we characterize the probability that the first TCR triggering is induced by a rare agonist antigen and not by that of an abundant self-antigen. We show that defining positive immune outcomes as resilience to extreme statistics and sensitivity to rare events mitigates classic tradeoffs associated with KP. By choosing a sufficient number of KP steps, our model is able to yield single agonist sensitivity whilst remaining non-reactive to large populations of self antigen, even when self and agonist antigen are similar in dissociation rate to the TCR but differ largely in expression. Additionally, our model achieves high levels of accuracy even when agonist positive APCs encounters are rare. Finally, we discuss potential biological costs associated with high classification accuracy, particularly in challenging T cell environments.
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Affiliation(s)
- Jonathan Morgan
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, South Bend, Indiana, United States of America
- Biophysics Graduate Program, University of Notre Dame, South Bend, Indiana, United States of America
| | - Alan E. Lindsay
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, South Bend, Indiana, United States of America
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13
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Abstract
Specialized subpopulations of CD4+ T cells survey major histocompatibility complex class II-peptide complexes to control phagosomal infections, help B cells, regulate tissue homeostasis and repair or perform immune regulation. Memory CD4+ T cells are positioned throughout the body and not only protect the tissues from reinfection and cancer, but also participate in allergy, autoimmunity, graft rejection and chronic inflammation. Here we provide updates on our understanding of the longevity, functional heterogeneity, differentiation, plasticity, migration and human immunodeficiency virus reservoirs as well as key technological advances that are facilitating the characterization of memory CD4+ T cell biology.
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Affiliation(s)
- Marco Künzli
- Center for Immunology, Department of Microbiology and Immunology, University of Minnesota, Minneapolis, MN, USA
| | - David Masopust
- Center for Immunology, Department of Microbiology and Immunology, University of Minnesota, Minneapolis, MN, USA.
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14
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Pettmann J, Awada L, Różycki B, Huhn A, Faour S, Kutuzov M, Limozin L, Weikl TR, van der Merwe PA, Robert P, Dushek O. Mechanical forces impair antigen discrimination by reducing differences in T-cell receptor/peptide-MHC off-rates. EMBO J 2023; 42:e111841. [PMID: 36484367 PMCID: PMC10068313 DOI: 10.15252/embj.2022111841] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 11/08/2022] [Accepted: 11/16/2022] [Indexed: 12/13/2022] Open
Abstract
T cells use their T-cell receptors (TCRs) to discriminate between lower-affinity self and higher-affinity foreign peptide major-histocompatibility-complexes (pMHCs) based on the TCR/pMHC off-rate. It is now appreciated that T cells generate mechanical forces during this process but how force impacts the TCR/pMHC off-rate remains debated. Here, we measured the effect of mechanical force on the off-rate of multiple TCR/pMHC interactions. Unexpectedly, we found that lower-affinity TCR/pMHCs with faster solution off-rates were more resistant to mechanical force (weak slip or catch bonds) than higher-affinity interactions (strong slip bonds). This was confirmed by molecular dynamics simulations. Consistent with these findings, we show that the best-characterized catch bond, involving the OT-I TCR, has a low affinity and an exceptionally fast solution off-rate. Our findings imply that reducing forces on the TCR/pMHC interaction improves antigen discrimination, and we suggest a role for the adhesion receptors CD2 and LFA-1 in force-shielding the TCR/pMHC interaction.
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Affiliation(s)
| | - Lama Awada
- Laboratoire Adhesion et InflammationAix Marseille University UM 61, INSERM UMRS 1067, CNRS UMR 7333MarseilleFrance
| | | | - Anna Huhn
- Sir William Dunn School of PathologyUniversity of OxfordOxfordUK
| | - Sara Faour
- Laboratoire Adhesion et InflammationAix Marseille University UM 61, INSERM UMRS 1067, CNRS UMR 7333MarseilleFrance
| | - Mikhail Kutuzov
- Sir William Dunn School of PathologyUniversity of OxfordOxfordUK
| | - Laurent Limozin
- Laboratoire Adhesion et InflammationAix Marseille University UM 61, INSERM UMRS 1067, CNRS UMR 7333MarseilleFrance
| | - Thomas R Weikl
- Max Planck Institute of Colloids and InterfacesPotsdamGermany
| | | | - Philippe Robert
- Laboratoire Adhesion et InflammationAix Marseille University UM 61, INSERM UMRS 1067, CNRS UMR 7333MarseilleFrance
- Assistance Publique‐Hôpitaux de MarseilleMarseilleFrance
| | - Omer Dushek
- Sir William Dunn School of PathologyUniversity of OxfordOxfordUK
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15
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Stadinski BD, Cleveland SB, Brehm MA, Greiner DL, Huseby PG, Huseby ES. I-A g7 β56/57 polymorphisms regulate non-cognate negative selection to CD4 + T cell orchestrators of type 1 diabetes. Nat Immunol 2023; 24:652-663. [PMID: 36807641 PMCID: PMC10623581 DOI: 10.1038/s41590-023-01441-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 01/20/2023] [Indexed: 02/22/2023]
Abstract
Genetic susceptibility to type 1 diabetes is associated with homozygous expression of major histocompatibility complex class II alleles that carry specific beta chain polymorphisms. Why heterozygous expression of these major histocompatibility complex class II alleles does not confer a similar predisposition is unresolved. Using a nonobese diabetic mouse model, here we show that heterozygous expression of the type 1 diabetes-protective allele I-Ag7 β56P/57D induces negative selection to the I-Ag7-restricted T cell repertoire, including beta-islet-specific CD4+ T cells. Surprisingly, negative selection occurs despite I-Ag7 β56P/57D having a reduced ability to present beta-islet antigens to CD4+ T cells. Peripheral manifestations of non-cognate negative selection include a near complete loss of beta-islet-specific CXCR6+ CD4+ T cells, an inability to cross-prime islet-specific glucose-6-phosphatase catalytic subunit-related protein and insulin-specific CD8+ T cells and disease arrest at the insulitis stage. These data reveal that negative selection on non-cognate self-antigens in the thymus can promote T cell tolerance and protection from autoimmunity.
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Affiliation(s)
- Brian D Stadinski
- Department of Pathology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Sarah B Cleveland
- Department of Pathology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Michael A Brehm
- Department of Molecular Medicine, Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, MA, USA
| | - Dale L Greiner
- Department of Molecular Medicine, Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, MA, USA
| | - Priya G Huseby
- Department of Pathology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Eric S Huseby
- Department of Pathology, University of Massachusetts Medical School, Worcester, MA, USA.
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16
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Shevyrev DV, Tereshchenko VP, Sennikov SV. The Enigmatic Nature of the TCR-pMHC Interaction: Implications for CAR-T and TCR-T Engineering. Int J Mol Sci 2022; 23:ijms232314728. [PMID: 36499057 PMCID: PMC9740949 DOI: 10.3390/ijms232314728] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/11/2022] [Accepted: 11/21/2022] [Indexed: 11/29/2022] Open
Abstract
The interaction of the T-cell receptor (TCR) with a peptide in the major histocompatibility complex (pMHC) plays a central role in the adaptive immunity of higher chordates. Due to the high specificity and sensitivity of this process, the immune system quickly recognizes and efficiently responds to the appearance of foreign and altered self-antigens. This is important for ensuring anti-infectious and antitumor immunity, in addition to maintaining self-tolerance. The most common parameter used for assessing the specificity of TCR-pMHC interaction is affinity. This thermodynamic characteristic is widely used not only in various theoretical aspects, but also in practice, for example, in the engineering of various T-cell products with a chimeric (CAR-T) or artificial (TCR-engineered T-cell) antigen receptor. However, increasing data reveal the fact that, in addition to the thermodynamic component, the specificity of antigen recognition is based on the kinetics and mechanics of the process, having even greater influence on the selectivity of the process and T lymphocyte activation than affinity. Therefore, the kinetic and mechanical aspects of antigen recognition should be taken into account when designing artificial antigen receptors, especially those that recognize antigens in the MHC complex. This review describes the current understanding of the nature of the TCR-pMHC interaction, in addition to the thermodynamic, kinetic, and mechanical principles underlying the specificity and high sensitivity of this interaction.
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Affiliation(s)
- D. V. Shevyrev
- Laboratory of molecular Immunology, Research Institute for Fundamental and Clinical Immunology, 630099 Novosibirsk, Russia
- Center for Cell Technology and Immunology, Sirius University of Science and Technology, 354340 Sochi, Russia
- Correspondence: ; Tel.: +7-9231345505
| | - V. P. Tereshchenko
- Laboratory of molecular Immunology, Research Institute for Fundamental and Clinical Immunology, 630099 Novosibirsk, Russia
- Center for Cell Technology and Immunology, Sirius University of Science and Technology, 354340 Sochi, Russia
| | - S. V. Sennikov
- Laboratory of molecular Immunology, Research Institute for Fundamental and Clinical Immunology, 630099 Novosibirsk, Russia
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17
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Morgan J, Pettmann J, Dushek O, Lindsay AE. T cell microvilli simulations show operation near packing limit and impact on antigen recognition. Biophys J 2022; 121:4128-4136. [PMID: 36181267 PMCID: PMC9675027 DOI: 10.1016/j.bpj.2022.09.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 07/11/2022] [Accepted: 09/26/2022] [Indexed: 11/02/2022] Open
Abstract
T cells are immune cells that continuously scan for foreign-derived antigens on the surfaces of nearly all cells, termed antigen-presenting cells (APCs). They do this by dynamically extending numerous protrusions called microvilli (MVs) that contain T cell receptors toward the APC surface in order to scan for antigens. The number, size, and dynamics of these MVs, and the complex multiscale topography that results, play a yet unknown role in antigen recognition. We develop an anatomically informed model that confines antigen recognition to small areas representing MVs that can dynamically form and dissolve and use the model to study how MV dynamics impact antigen sensitivity and discrimination. We find that MV surveillance reduces antigen sensitivity compared with a completely flat interface, unless MV are stabilized in an antigen-dependent manner, and observe that MVs have only a modest impact on antigen discrimination. The model highlights that MV contacts optimize the competing demands of fast scanning speeds of the APC surface with antigen sensitivity. Our model predicts an interface packing fraction that corresponds closely to those observed experimentally, indicating that T cells operate their MVs near the limits imposed by anatomical and geometric constraints. Finally, we find that observed MV contact lifetimes can be largely influenced by conditions in the T cell/APC interface, with these lifetimes often being longer than the simulation or experimental observation period. This work highlights the role of MVs in antigen recognition.
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Affiliation(s)
- Jonathan Morgan
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, Indiana; Biophysics Graduate Program, University of Notre Dame, Notre Dame, Indiana
| | - Johannes Pettmann
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Omer Dushek
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Alan E Lindsay
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, Indiana.
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18
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Mao R, Kong W, He Y. The affinity of antigen-binding domain on the antitumor efficacy of CAR T cells: Moderate is better. Front Immunol 2022; 13:1032403. [PMID: 36325345 PMCID: PMC9618871 DOI: 10.3389/fimmu.2022.1032403] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 09/21/2022] [Indexed: 11/16/2022] Open
Abstract
The overall efficacy of chimeric antigen receptor modified T cells (CARTs) remain limited in solid tumors despite intensive studies that aim at targeting multiple antigens, enhancing migration, reducing tonic signaling, and improving tumor microenvironment. On the other hand, how the affinity and engaging kinetics of antigen-binding domain (ABD) affects the CART's efficacy has not been carefully investigated. In this article, we first analyzed 38 published solid tumor CART trials and correlated the response rate to their ABD affinity. Not surprisingly, majority (25 trials) of the CARTs utilized high-affinity ABDs, but generated merely 5.7% response rate. In contrast, 35% of the patients treated with the CARTs built from moderate-affinity ABDs had clinical responses. Thus, CARTs with moderate-affinity ABDs not only have less off-target toxicity, but also are more effective. We then reviewed the effects of ABD affinity on the biology and function of CARTs, providing further evidence that moderate-affinity ABDs may be better in CART development. In the end, we propose that a fast-on/fast-off (high Kon and Koff ) kinetics of CART-target engagement in solid tumor allow CARTs to generate sufficient signaling to kill tumor cells without being driven to exhaustion. We believe that studying the ABD affinity and the kinetics of CART-tumor interaction may hold a key to designing effective CARTs for solid tumors.
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Affiliation(s)
- Rui Mao
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Wanqing Kong
- South Carolina Governors School for Science and Math, Hartsville, SC, United States
| | - Yukai He
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, United States
- Department of Medicine, Medical College of Georgia, Augusta University, Augusta, GA, United States
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19
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Covalent TCR-peptide-MHC interactions induce T cell activation and redirect T cell fate in the thymus. Nat Commun 2022; 13:4951. [PMID: 35999236 PMCID: PMC9399087 DOI: 10.1038/s41467-022-32692-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 08/10/2022] [Indexed: 11/24/2022] Open
Abstract
Interactions between a T cell receptor (TCR) and a peptide-major histocompatibility complex (pMHC) ligand are typically mediated by noncovalent bonds. By studying T cells expressing natural or engineered TCRs, here we describe covalent TCR-pMHC interactions that involve a cysteine-cysteine disulfide bond between the TCR and the peptide. By introducing cysteines into a known TCR-pMHC combination, we demonstrate that disulfide bond formation does not require structural rearrangement of the TCR or the peptide. We further show these disulfide bonds still form even when the initial affinity of the TCR-pMHC interaction is low. Accordingly, TCR-peptide disulfide bonds facilitate T cell activation by pMHC ligands with a wide spectrum of affinities for the TCR. Physiologically, this mechanism induces strong Zap70-dependent TCR signaling, which triggers T cell deletion or agonist selection in the thymus cortex. Covalent TCR-pMHC interactions may thus underlie a physiological T cell activation mechanism that has applications in basic immunology and potentially in immunotherapy. Differentiation and activation of T cells are normally modulated by non-covalent interactions between T cell receptor (TCR) and antigenic peptides. Here the authors use step-wise mutations, biochemical characterization and structural insights to describe the contributions of natural covalent bonds between TCR and antigenic peptides during these processes.
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20
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Egan JR, Abu-Shah E, Dushek O, Elliott T, MacArthur BD. Fluctuations in T cell receptor and pMHC interactions regulate T cell activation. J R Soc Interface 2022; 19:20210589. [PMID: 35135295 PMCID: PMC8833104 DOI: 10.1098/rsif.2021.0589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Adaptive immune responses depend on interactions between T cell receptors (TCRs) and peptide major histocompatibility complex (pMHC) ligands located on the surface of T cells and antigen presenting cells (APCs), respectively. As TCRs and pMHCs are often only present at low copy numbers their interactions are inherently stochastic, yet the role of stochastic fluctuations on T cell function is unclear. Here, we introduce a minimal stochastic model of T cell activation that accounts for serial TCR-pMHC engagement, reversible TCR conformational change and TCR aggregation. Analysis of this model indicates that it is not the strength of binding between the T cell and the APC cell per se that elicits an immune response, but rather the information imparted to the T cell from the encounter, as assessed by the entropy rate of the TCR-pMHC binding dynamics. This view provides an information-theoretic interpretation of T cell activation that explains a range of experimental observations. Based on this analysis, we propose that effective T cell therapeutics may be enhanced by optimizing the inherent stochasticity of TCR-pMHC binding dynamics.
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Affiliation(s)
- Joseph R Egan
- Mathematical Sciences, Stem Cells and Regeneration, University of Southampton, Southampton SO17 1BJ, UK.,Institute for Life Sciences, Stem Cells and Regeneration, University of Southampton, Southampton SO17 1BJ, UK.,Centre for Cancer Immunology, University Hospital Southampton, Southampton SO16 6YD, UK.,Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Enas Abu-Shah
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK.,Kennedy Institute of Rheumatology, University of Oxford, Oxford OX3 7FY, UK
| | - Omer Dushek
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Tim Elliott
- Institute for Life Sciences, Stem Cells and Regeneration, University of Southampton, Southampton SO17 1BJ, UK.,Centre for Cancer Immunology, University Hospital Southampton, Southampton SO16 6YD, UK.,Nuffield Department of Medicine, University of Oxford, Oxford OX3 7BN, UK
| | - Ben D MacArthur
- Mathematical Sciences, Stem Cells and Regeneration, University of Southampton, Southampton SO17 1BJ, UK.,Institute for Life Sciences, Stem Cells and Regeneration, University of Southampton, Southampton SO17 1BJ, UK.,Centre for Human Development, Stem Cells and Regeneration, University of Southampton, Southampton SO17 1BJ, UK.,Alan Turing Institute, London NW1 2DB, UK
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21
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Vander Mause ER, Atanackovic D, Lim CS, Luetkens T. Roadmap to affinity-tuned antibodies for enhanced chimeric antigen receptor T cell function and selectivity. Trends Biotechnol 2022; 40:875-890. [DOI: 10.1016/j.tibtech.2021.12.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 12/29/2022]
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22
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Pack AD, Schwartzhoff PV, Zacharias ZR, Fernandez-Ruiz D, Heath WR, Gurung P, Legge KL, Janse CJ, Butler NS. Hemozoin-mediated inflammasome activation limits long-lived anti-malarial immunity. Cell Rep 2021; 36:109586. [PMID: 34433049 PMCID: PMC8432597 DOI: 10.1016/j.celrep.2021.109586] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 05/21/2021] [Accepted: 07/30/2021] [Indexed: 12/04/2022] Open
Abstract
During acute malaria, most individuals mount robust inflammatory responses that limit parasite burden. However, long-lived sterilizing anti-malarial memory responses are not efficiently induced, even following repeated Plasmodium exposures. Using multiple Plasmodium species, genetically modified parasites, and combinations of host genetic and pharmacologic approaches, we find that the deposition of the malarial pigment hemozoin directly limits the abundance and capacity of conventional type 1 dendritic cells to prime helper T cell responses. Hemozoin-induced dendritic cell dysfunction results in aberrant Plasmodium-specific CD4 T follicular helper cell differentiation, which constrains memory B cell and long-lived plasma cell formation. Mechanistically, we identify that dendritic cell-intrinsic NLRP3 inflammasome activation reduces conventional type 1 dendritic cell abundance, phagocytosis, and T cell priming functions in vivo. These data identify biological consequences of hemozoin deposition during malaria and highlight the capacity of the malarial pigment to program immune evasion during the earliest events following an initial Plasmodium exposure.
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Affiliation(s)
- Angela D Pack
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, USA
| | | | - Zeb R Zacharias
- Department of Pathology, University of Iowa, Iowa City, IA, USA
| | - Daniel Fernandez-Ruiz
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, VIC 3000, Australia
| | - William R Heath
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, VIC 3000, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of Melbourne, Parkville, VIC 3010, Australia
| | - Prajwal Gurung
- Department of Internal Medicine, University of Iowa, Iowa City, IA, USA; Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA, USA
| | - Kevin L Legge
- Department of Pathology, University of Iowa, Iowa City, IA, USA; Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA, USA
| | - Chris J Janse
- Leiden Malaria Research Group, Centre of Infectious Diseases, Leiden University Medical Centre, Leiden 233 ZA, the Netherlands
| | - Noah S Butler
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, USA; Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA, USA.
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23
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Dileepan T, Malhotra D, Kotov DI, Kolawole EM, Krueger PD, Evavold BD, Jenkins MK. MHC class II tetramers engineered for enhanced binding to CD4 improve detection of antigen-specific T cells. Nat Biotechnol 2021; 39:943-948. [PMID: 33941928 PMCID: PMC10666075 DOI: 10.1038/s41587-021-00893-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 03/12/2021] [Indexed: 12/15/2022]
Abstract
The ability to identify T cells that recognize specific peptide antigens bound to major histocompatibility complex (MHC) molecules has enabled enumeration and molecular characterization of the lymphocytes responsible for cell-mediated immunity. Fluorophore-labeled peptide:MHC class I (p:MHCI) tetramers are well-established reagents for identifying antigen-specific CD8+ T cells by flow cytometry, but efforts to extend the approach to CD4+ T cells have been less successful, perhaps owing to lower binding strength between CD4 and MHC class II (MHCII) molecules. Here we show that p:MHCII tetramers engineered by directed evolution for enhanced CD4 binding outperform conventional tetramers for the detection of cognate T cells. Using the engineered tetramers, we identified about twice as many antigen-specific CD4+ T cells in mice immunized against multiple peptides than when using traditional tetramers. CD4 affinity-enhanced p:MHCII tetramers, therefore, allow direct sampling of antigen-specific CD4+ T cells that cannot be accessed with conventional p:MHCII tetramer technology. These new reagents could provide a deeper understanding of the T cell repertoire.
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Affiliation(s)
- Thamotharampillai Dileepan
- Department of Microbiology and Immunology, Center for Immunology, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Deepali Malhotra
- Department of Microbiology and Immunology, Center for Immunology, University of Minnesota Medical School, Minneapolis, MN, USA
- AstraZeneca, Gaithersburg, MD, USA
| | - Dmitri I Kotov
- Department of Microbiology and Immunology, Center for Immunology, University of Minnesota Medical School, Minneapolis, MN, USA
- University of California, Berkeley, Berkeley, CA, USA
| | - Elizabeth M Kolawole
- Department of Pathology, Microbiology and Immunology, University of Utah, Salt Lake City, UT, USA
| | - Peter D Krueger
- Department of Microbiology and Immunology, Center for Immunology, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Brian D Evavold
- Department of Pathology, Microbiology and Immunology, University of Utah, Salt Lake City, UT, USA
| | - Marc K Jenkins
- Department of Microbiology and Immunology, Center for Immunology, University of Minnesota Medical School, Minneapolis, MN, USA.
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24
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Abstract
T cell activation is a critical event in the adaptive immune response, indispensable for cell-mediated and humoral immunity as well as for immune regulation. Recent years have witnessed an emerging trend emphasizing the essential role that physical force and mechanical properties play at the T cell interface. In this review, we integrate current knowledge of T cell antigen recognition and the different models of T cell activation from the perspective of mechanobiology, focusing on the interaction between the T cell receptor (TCR) and the peptide-major histocompatibility complex (pMHC) antigen. We address the shortcomings of TCR affinity alone in explaining T cell functional outcomes and the rising status of force-regulated TCR bond lifetimes, most notably the TCR catch bond. Ultimately, T cell activation and the ensuing physiological responses result from mechanical interaction between TCRs and the pMHC. Expected final online publication date for the Annual Review of Cell and Developmental Biology, Volume 37 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Baoyu Liu
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA; , ,
| | - Elizabeth M Kolawole
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA; , ,
| | - Brian D Evavold
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA; , ,
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25
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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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26
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Cross-TCR Antagonism Revealed by Optogenetically Tuning the Half-Life of the TCR Ligand Binding. Int J Mol Sci 2021; 22:ijms22094920. [PMID: 34066527 PMCID: PMC8124730 DOI: 10.3390/ijms22094920] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/20/2021] [Accepted: 04/23/2021] [Indexed: 12/27/2022] Open
Abstract
Activation of T cells by agonistic peptide-MHC can be inhibited by antagonistic ones. However, the exact mechanism remains elusive. We used Jurkat cells expressing two different TCRs and tested whether stimulation of the endogenous TCR by agonistic anti-Vβ8 antibodies can be modulated by ligand-binding to the second, optogenetic TCR. The latter TCR uses phytochrome B tetramers (PhyBt) as ligand, the binding half-life of which can be altered by light. We show that this half-life determined whether the PhyBt acted as a second agonist (long half-life), an antagonist (short half-life) or did not have any influence (very short half-life) on calcium influx. A mathematical model of this cross-antagonism shows that a mechanism based on an inhibitory signal generated by early recruitment of a phosphatase and an activating signal by later recruitment of a kinase explains the data.
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27
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Kervevan J, Chakrabarti LA. Role of CD4+ T Cells in the Control of Viral Infections: Recent Advances and Open Questions. Int J Mol Sci 2021; 22:E523. [PMID: 33430234 PMCID: PMC7825705 DOI: 10.3390/ijms22020523] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/23/2020] [Accepted: 12/30/2020] [Indexed: 12/26/2022] Open
Abstract
CD4+ T cells orchestrate adaptive immune responses through their capacity to recruit and provide help to multiple immune effectors, in addition to exerting direct effector functions. CD4+ T cells are increasingly recognized as playing an essential role in the control of chronic viral infections. In this review, we present recent advances in understanding the nature of CD4+ T cell help provided to antiviral effectors. Drawing from our studies of natural human immunodeficiency virus (HIV) control, we then focus on the role of high-affinity T cell receptor (TCR) clonotypes in mediating antiviral CD4+ T cell responses. Last, we discuss the role of TCR affinity in determining CD4+ T cell differentiation, reviewing the at times divergent studies associating TCR signal strength to the choice of a T helper 1 (Th1) or a T follicular helper (Tfh) cell fate.
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Affiliation(s)
- Jérôme Kervevan
- Control of Chronic Viral Infections Group (CIVIC), Virus and Immunity Unit, Institut Pasteur, 75724 Paris, France;
- CNRS UMR, 3569 Paris, France
| | - Lisa A. Chakrabarti
- Control of Chronic Viral Infections Group (CIVIC), Virus and Immunity Unit, Institut Pasteur, 75724 Paris, France;
- CNRS UMR, 3569 Paris, France
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28
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TCR Recognition of Peptide-MHC-I: Rule Makers and Breakers. Int J Mol Sci 2020; 22:ijms22010068. [PMID: 33374673 PMCID: PMC7793522 DOI: 10.3390/ijms22010068] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 12/16/2020] [Accepted: 12/21/2020] [Indexed: 12/15/2022] Open
Abstract
T cells are a critical part of the adaptive immune system that are able to distinguish between healthy and unhealthy cells. Upon recognition of protein fragments (peptides), activated T cells will contribute to the immune response and help clear infection. The major histocompatibility complex (MHC) molecules, or human leukocyte antigens (HLA) in humans, bind these peptides to present them to T cells that recognise them with their surface T cell receptors (TCR). This recognition event is the first step that leads to T cell activation, and in turn can dictate disease outcomes. The visualisation of TCR interaction with pMHC using structural biology has been crucial in understanding this key event, unravelling the parameters that drive this interaction and their impact on the immune response. The last five years has been the most productive within the field, wherein half of current unique TCR-pMHC-I structures to date were determined within this time. Here, we review the new insights learned from these recent TCR-pMHC-I structures and their impact on T cell activation.
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29
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Kolawole EM, Lamb TJ, Evavold BD. Relationship of 2D Affinity to T Cell Functional Outcomes. Int J Mol Sci 2020; 21:E7969. [PMID: 33120989 PMCID: PMC7662510 DOI: 10.3390/ijms21217969] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/14/2020] [Accepted: 10/23/2020] [Indexed: 12/11/2022] Open
Abstract
T cells are critical for a functioning adaptive immune response and a strong correlation exists between T cell responses and T cell receptor (TCR): peptide-loaded MHC (pMHC) binding. Studies that utilize pMHC tetramer, multimers, and assays of three-dimensional (3D) affinity have provided advancements in our understanding of T cell responses across different diseases. However, these technologies focus on higher affinity and avidity T cells while missing the lower affinity responders. Lower affinity TCRs in expanded polyclonal populations almost always constitute a significant proportion of the response with cells mediating different effector functions associated with variation in the proportion of high and low affinity T cells. Since lower affinity T cells expand and are functional, a fully inclusive view of T cell responses is required to accurately interpret the role of affinity for adaptive T cell immunity. For example, low affinity T cells are capable of inducing autoimmune disease and T cells with an intermediate affinity have been shown to exhibit an optimal anti-tumor response. Here, we focus on how affinity of the TCR may relate to T cell phenotype and provide examples where 2D affinity influences functional outcomes.
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Affiliation(s)
| | | | - Brian D. Evavold
- Department of Pathology, University of Utah, 15 N Medical Drive, Salt Lake City, UT 84112, USA; (E.M.K.); (T.J.L.)
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30
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Strength of tonic T cell receptor signaling instructs T follicular helper cell-fate decisions. Nat Immunol 2020; 21:1384-1396. [PMID: 32989327 PMCID: PMC7578106 DOI: 10.1038/s41590-020-0781-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 08/11/2020] [Indexed: 12/17/2022]
Abstract
T follicular helper (TFH) cells are critical in adaptive immune responses to pathogens and vaccines; however, what drives the initiation of their developmental program remains unclear. Studies suggest that a T cell antigen receptor (TCR)-dependent mechanism may be responsible for the earliest TFH cell-fate decision, but a critical aspect of the TCR has been overlooked: tonic TCR signaling. We hypothesized that tonic signaling influences early TFH cell development. Here, two murine TCR-transgenic CD4+ T cells, LLO56 and LLO118, which recognize the same antigenic peptide presented on major histocompatibility complex molecules but experience disparate strengths of tonic signaling, revealed low tonic signaling promotes TFH cell differentiation. Polyclonal T cells paralleled these findings, with naive Nur77 expression distinguishing TFH cell potential. Two mouse lines were also generated to both increase and decrease tonic signaling strength, directly establishing an inverse relationship between tonic signaling strength and TFH cell development. Our findings elucidate a central role for tonic TCR signaling in early TFH cell-lineage decisions.
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31
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Céspedes PF, Beckers D, Dustin ML, Sezgin E. Model membrane systems to reconstitute immune cell signaling. FEBS J 2020; 288:1070-1090. [DOI: 10.1111/febs.15488] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/26/2020] [Accepted: 07/14/2020] [Indexed: 12/26/2022]
Affiliation(s)
- Pablo F. Céspedes
- Kennedy Institute of Rheumatology Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences University of Oxford UK
| | - Daniel Beckers
- MRC Human Immunology Unit MRC Weatherall Institute of Molecular Medicine University of Oxford UK
| | - Michael L. Dustin
- Kennedy Institute of Rheumatology Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences University of Oxford UK
| | - Erdinc Sezgin
- MRC Human Immunology Unit MRC Weatherall Institute of Molecular Medicine University of Oxford UK
- Science for Life Laboratory Department of Women's and Children's Health Karolinska Institutet Stockholm Sweden
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32
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Teimouri H, Kolomeisky AB. Relaxation Times of Ligand-Receptor Complex Formation Control T Cell Activation. Biophys J 2020; 119:182-189. [PMID: 32562619 DOI: 10.1016/j.bpj.2020.06.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 05/20/2020] [Accepted: 06/01/2020] [Indexed: 11/18/2022] Open
Abstract
One of the most important functions of immune T cells is to recognize the presence of the pathogen-derived ligands and to quickly respond to them while at the same time not responding to its own ligands. This is known as absolute discrimination, and it is one of the most challenging phenomena to explain. The effectiveness of pathogen detection by T cell receptor is limited by chemical similarity of foreign and self-peptides and very low concentrations of foreign ligands. We propose a new mechanism of how absolute discrimination by T cells might function. It is suggested that the decision to activate or not to activate the immune response is controlled by the time to reach the stationary concentration of the T-cell-receptor-ligand-activated complex, which transfers the signal to downstream cellular biochemical networks. Our theoretical method models T cell receptor phosphorylation events as a sequence of stochastic transitions between discrete biochemical states, and this allows us to explicitly describe the dynamical properties of the system. It is found that the proposed criterion on the relaxation times is able to explain available experimental observations. In addition, we suggest that the level of stochastic noise might be an additional factor in the activation mechanisms. Furthermore, our theoretical approach explicitly analyzes the relationships between speed, sensitivity, and specificity of T cell functioning, which are the main characteristics of the process. Thus, it clarifies the molecular picture of T cell activation in immune response.
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Affiliation(s)
- Hamid Teimouri
- Department of Chemistry, Rice University, Houston, Texas; Center for Theoretical Biological Physics, Rice University, Houston, Texas
| | - Anatoly B Kolomeisky
- Department of Chemistry, Rice University, Houston, Texas; Center for Theoretical Biological Physics, Rice University, Houston, Texas; Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas; Department of Physics and Astronomy, Rice University, Houston, Texas.
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33
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Bhattacharyya ND, Feng CG. Regulation of T Helper Cell Fate by TCR Signal Strength. Front Immunol 2020; 11:624. [PMID: 32508803 PMCID: PMC7248325 DOI: 10.3389/fimmu.2020.00624] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/19/2020] [Indexed: 12/16/2022] Open
Abstract
T cells are critical in orchestrating protective immune responses to cancer and an array of pathogens. The interaction between a peptide MHC (pMHC) complex on antigen presenting cells (APCs) and T cell receptors (TCRs) on T cells initiates T cell activation, division, and clonal expansion in secondary lymphoid organs. T cells must also integrate multiple T cell-intrinsic and extrinsic signals to acquire the effector functions essential for the defense against invading microbes. In the case of T helper cell differentiation, while innate cytokines have been demonstrated to shape effector CD4+ T lymphocyte function, the contribution of TCR signaling strength to T helper cell differentiation is less understood. In this review, we summarize the signaling cascades regulated by the strength of TCR stimulation. Various mechanisms in which TCR signal strength controls T helper cell expansion and differentiation are also discussed.
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Affiliation(s)
- Nayan D Bhattacharyya
- Immunology and Host Defense Group, Discipline of Infectious Diseases and Immunology, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Tuberculosis Research Program, Centenary Institute, The University of Sydney, Sydney, NSW, Australia
| | - Carl G Feng
- Immunology and Host Defense Group, Discipline of Infectious Diseases and Immunology, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.,Tuberculosis Research Program, Centenary Institute, The University of Sydney, Sydney, NSW, Australia
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34
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Affiliation(s)
- Pirooz Zareie
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Carine Farenc
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Nicole L. La Gruta
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Australia
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35
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Xu X, Li H, Xu C. Structural understanding of T cell receptor triggering. Cell Mol Immunol 2020; 17:193-202. [PMID: 32047259 PMCID: PMC7052162 DOI: 10.1038/s41423-020-0367-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/08/2020] [Indexed: 11/09/2022] Open
Abstract
The T cell receptor (TCR) is one of the most complicated receptors in mammalian cells, and its triggering mechanism remains mysterious. As an octamer complex, TCR comprises an antigen-binding subunit (TCRαβ) and three CD3 signaling subunits (CD3ζζ, CD3δε, and CD3γε). Engagement of TCRαβ with an antigen peptide presented on the MHC leads to tyrosine phosphorylation of the immunoreceptor tyrosine-based activation motif (ITAM) in CD3 cytoplasmic domains (CDs), thus translating extracellular binding kinetics to intracellular signaling events. Whether conformational change plays an important role in the transmembrane signal transduction of TCR is under debate. Attracted by the complexity and functional importance of TCR, many groups have been studying TCR structure and triggering for decades using diverse biochemical and biophysical tools. Here, we synthesize these structural studies and discuss the relevance of the conformational change model in TCR triggering.
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Affiliation(s)
- Xinyi Xu
- State Key Laboratory of Molecular Biology, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, 320 Yueyang Road, 200031, Shanghai, China
| | - Hua Li
- State Key Laboratory of Molecular Biology, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, 320 Yueyang Road, 200031, Shanghai, China
| | - Chenqi Xu
- State Key Laboratory of Molecular Biology, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, 320 Yueyang Road, 200031, Shanghai, China.
- School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, 201210, Shanghai, China.
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36
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Schamel WW, Alarcon B, Minguet S. The TCR is an allosterically regulated macromolecular machinery changing its conformation while working. Immunol Rev 2020; 291:8-25. [PMID: 31402501 DOI: 10.1111/imr.12788] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 05/30/2019] [Indexed: 12/13/2022]
Abstract
The αβ T-cell receptor (TCR) is a multiprotein complex controlling the activation of T cells. Although the structure of the complete TCR is not known, cumulative evidence supports that the TCR cycles between different conformational states that are promoted either by thermal motion or by force. These structural transitions determine whether the TCR engages intracellular effectors or not, regulating TCR phosphorylation and signaling. As for other membrane receptors, ligand binding selects and stabilizes the TCR in active conformations, and/or switches the TCR to activating states that were not visited before ligand engagement. Here we review the main models of TCR allostery, that is, ligand binding at TCRαβ changes the structure at CD3 and ζ. (a) The ITAM and proline-rich sequence exposure model, in which the TCR's cytoplasmic tails shield each other and ligand binding exposes them for phosphorylation. (b) The membrane-ITAM model, in which the CD3ε and ζ tails are sequestered inside the membrane and again ligand binding exposes them. (c) The mechanosensor model in which ligand binding exerts force on the TCR, inducing structural changes that allow signaling. Since these models are complementary rather than competing, we propose a unified model that aims to incorporate all existing data.
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Affiliation(s)
- Wolfgang W Schamel
- Department of Immunology, Faculty of Biology, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Center of Chronic Immunodeficiency CCI, University Clinics and Medical Faculty, Freiburg, Germany
| | - Balbino Alarcon
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | - Susana Minguet
- Department of Immunology, Faculty of Biology, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Center of Chronic Immunodeficiency CCI, University Clinics and Medical Faculty, Freiburg, Germany
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37
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François P, Zilman A. Physical approaches to receptor sensing and ligand discrimination. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.coisb.2019.10.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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38
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Andreotti AH, Joseph RE, Conley JM, Iwasa J, Berg LJ. Multidomain Control Over TEC Kinase Activation State Tunes the T Cell Response. Annu Rev Immunol 2019; 36:549-578. [PMID: 29677469 DOI: 10.1146/annurev-immunol-042617-053344] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Signaling through the T cell antigen receptor (TCR) activates a series of tyrosine kinases. Directly associated with the TCR, the SRC family kinase LCK and the SYK family kinase ZAP-70 are essential for all downstream responses to TCR stimulation. In contrast, the TEC family kinase ITK is not an obligate component of the TCR cascade. Instead, ITK functions as a tuning dial, to translate variations in TCR signal strength into differential programs of gene expression. Recent insights into TEC kinase structure have provided a view into the molecular mechanisms that generate different states of kinase activation. In resting lymphocytes, TEC kinases are autoinhibited, and multiple interactions between the regulatory and kinase domains maintain low activity. Following TCR stimulation, newly generated signaling modules compete with the autoinhibited core and shift the conformational ensemble to the fully active kinase. This multidomain control over kinase activation state provides a structural mechanism to account for ITK's ability to tune the TCR signal.
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Affiliation(s)
- Amy H Andreotti
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA; ,
| | - Raji E Joseph
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA; ,
| | - James M Conley
- Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA; ,
| | - Janet Iwasa
- Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112, USA;
| | - Leslie J Berg
- Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA; ,
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39
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Fernandes RA, Ganzinger KA, Tzou JC, Jönsson P, Lee SF, Palayret M, Santos AM, Carr AR, Ponjavic A, Chang VT, Macleod C, Lagerholm BC, Lindsay AE, Dushek O, Tilevik A, Davis SJ, Klenerman D. A cell topography-based mechanism for ligand discrimination by the T cell receptor. Proc Natl Acad Sci U S A 2019; 116:14002-14010. [PMID: 31221762 PMCID: PMC6628812 DOI: 10.1073/pnas.1817255116] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The T cell receptor (TCR) initiates the elimination of pathogens and tumors by T cells. To avoid damage to the host, the receptor must be capable of discriminating between wild-type and mutated self and nonself peptide ligands presented by host cells. Exactly how the TCR does this is unknown. In resting T cells, the TCR is largely unphosphorylated due to the dominance of phosphatases over the kinases expressed at the cell surface. However, when agonist peptides are presented to the TCR by major histocompatibility complex proteins expressed by antigen-presenting cells (APCs), very fast receptor triggering, i.e., TCR phosphorylation, occurs. Recent work suggests that this depends on the local exclusion of the phosphatases from regions of contact of the T cells with the APCs. Here, we developed and tested a quantitative treatment of receptor triggering reliant only on TCR dwell time in phosphatase-depleted cell contacts constrained in area by cell topography. Using the model and experimentally derived parameters, we found that ligand discrimination likely depends crucially on individual contacts being ∼200 nm in radius, matching the dimensions of the surface protrusions used by T cells to interrogate their targets. The model not only correctly predicted the relative signaling potencies of known agonists and nonagonists but also achieved this in the absence of kinetic proofreading. Our work provides a simple, quantitative, and predictive molecular framework for understanding why TCR triggering is so selective and fast and reveals that, for some receptors, cell topography likely influences signaling outcomes.
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Affiliation(s)
- Ricardo A Fernandes
- Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, OX3 9DS Oxford, United Kingdom
- Medical Research Council Human Immunology Unit, John Radcliffe Hospital, University of Oxford, OX3 9DS Oxford, United Kingdom
| | - Kristina A Ganzinger
- Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - Justin C Tzou
- Department of Applied & Computational Mathematics & Statistics, University of Notre Dame, Notre Dame, IN 46556
| | - Peter Jönsson
- Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - Steven F Lee
- Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - Matthieu Palayret
- Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - Ana Mafalda Santos
- Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, OX3 9DS Oxford, United Kingdom
- Medical Research Council Human Immunology Unit, John Radcliffe Hospital, University of Oxford, OX3 9DS Oxford, United Kingdom
| | - Alexander R Carr
- Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - Aleks Ponjavic
- Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - Veronica T Chang
- Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, OX3 9DS Oxford, United Kingdom
- Medical Research Council Human Immunology Unit, John Radcliffe Hospital, University of Oxford, OX3 9DS Oxford, United Kingdom
| | - Charlotte Macleod
- Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - B Christoffer Lagerholm
- Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, OX3 9DS Oxford, United Kingdom
| | - Alan E Lindsay
- Mathematics Department, University of British Columbia, Vancouver, BC V6T 1Z2, Canada
| | - Omer Dushek
- Sir William Dunn School of Pathology, University of Oxford, OX1 3RE Oxford, United Kingdom
- Wolfson Centre for Mathematical Biology, University of Oxford, OX1 3RE Oxford, United Kingdom
| | - Andreas Tilevik
- School of Bioscience, University of Skövde, 541 28 Skövde, Sweden
| | - Simon J Davis
- Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, OX3 9DS Oxford, United Kingdom;
- Medical Research Council Human Immunology Unit, John Radcliffe Hospital, University of Oxford, OX3 9DS Oxford, United Kingdom
| | - David Klenerman
- Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom;
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40
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Abstract
T cells initiate and regulate adaptive immune responses that can clear infections. To do this, they use their T cell receptors (TCRs) to continually scan the surfaces of other cells for cognate peptide antigens presented on major histocompatibility complexes (pMHCs). Experimental work has established that as few 1-10 pMHCs are sufficient to activate T cells. This sensitivity is remarkable in light of a number of factors, including the observation that the TCR and pMHC are short molecules relative to highly abundant long surface molecules, such as CD45, that can hinder initial binding, and moreover, the TCR/pMHC interaction is of weak affinity with solution lifetimes of approximately 1 second. Here, we review experimental and mathematical work that has contributed to uncovering molecular mechanisms of T cell sensitivity. We organize the mechanisms by where they act in the pathway to activate T cells, namely mechanisms that (a) promote TCR/pMHC binding, (b) induce rapid TCR signaling, and (c) amplify TCR signaling. We discuss work showing that high sensitivity reduces antigen specificity unless molecular feedbacks are invoked. We conclude by summarizing a number of open questions.
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Affiliation(s)
| | - Omer Dushek
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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41
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A temporal thymic selection switch and ligand binding kinetics constrain neonatal Foxp3 + T reg cell development. Nat Immunol 2019; 20:1046-1058. [PMID: 31209405 DOI: 10.1038/s41590-019-0414-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 04/29/2019] [Indexed: 12/21/2022]
Abstract
The neonatal thymus generates Foxp3+ regulatory T (tTreg) cells that are critical in controlling immune homeostasis and preventing multiorgan autoimmunity. The role of antigen specificity on neonatal tTreg cell selection is unresolved. Here we identify 17 self-peptides recognized by neonatal tTreg cells, and reveal ligand specificity patterns that include self-antigens presented in an age- and inflammation-dependent manner. Fate-mapping studies of neonatal peptidyl arginine deiminase type IV (Padi4)-specific thymocytes reveal disparate fate choices. Neonatal thymocytes expressing T cell receptors that engage IAb-Padi4 with moderate dwell times within a conventional docking orientation are exported as tTreg cells. In contrast, Padi4-specific T cell receptors with short dwell times are expressed on CD4+ T cells, while long dwell times induce negative selection. Temporally, Padi4-specific thymocytes are subject to a developmental stage-specific change in negative selection, which precludes tTreg cell development. Thus, a temporal switch in negative selection and ligand binding kinetics constrains the neonatal tTreg selection window.
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42
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Tischer DK, Weiner OD. Light-based tuning of ligand half-life supports kinetic proofreading model of T cell signaling. eLife 2019; 8:42498. [PMID: 30947808 PMCID: PMC6488292 DOI: 10.7554/elife.42498] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 04/03/2019] [Indexed: 11/30/2022] Open
Abstract
T cells are thought to discriminate self from foreign peptides by converting small differences in ligand binding half-life into large changes in cell signaling. Such a kinetic proofreading model has been difficult to test directly, as existing methods of altering ligand binding half-life also change other potentially important biophysical parameters, most notably the mechanical stability of the receptor-ligand interaction. Here we develop an optogenetic approach to specifically tune the binding half-life of a chimeric antigen receptor without changing other binding parameters and provide direct evidence of kinetic proofreading in T cell signaling. This half-life discrimination is executed in the proximal signaling pathway, downstream of ZAP70 recruitment and upstream of diacylglycerol accumulation. Our methods represent a general tool for temporal and spatial control of T cell signaling and extend the reach of optogenetics to probe pathways where the individual molecular kinetics, rather than the ensemble average, gates downstream signaling.
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Affiliation(s)
- Doug K Tischer
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Orion David Weiner
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
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43
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Yousefi OS, Günther M, Hörner M, Chalupsky J, Wess M, Brandl SM, Smith RW, Fleck C, Kunkel T, Zurbriggen MD, Höfer T, Weber W, Schamel WW. Optogenetic control shows that kinetic proofreading regulates the activity of the T cell receptor. eLife 2019; 8:42475. [PMID: 30947807 PMCID: PMC6488296 DOI: 10.7554/elife.42475] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 03/05/2019] [Indexed: 12/18/2022] Open
Abstract
The immune system distinguishes between self and foreign antigens. The kinetic proofreading (KPR) model proposes that T cells discriminate self from foreign ligands by the different ligand binding half-lives to the T cell receptor (TCR). It is challenging to test KPR as the available experimental systems fall short of only altering the binding half-lives and keeping other parameters of the interaction unchanged. We engineered an optogenetic system using the plant photoreceptor phytochrome B (PhyB) as a ligand to selectively control the dynamics of ligand binding to the TCR by light. This opto-ligand-TCR system was combined with the unique property of PhyB to continuously cycle between the binding and non-binding states under red light, with the light intensity determining the cycling rate and thus the binding duration. Mathematical modeling of our experimental datasets showed that indeed the ligand-TCR interaction half-life is the decisive factor for activating downstream TCR signaling, substantiating KPR.
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Affiliation(s)
- O Sascha Yousefi
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Matthias Günther
- Division of Theoretical Systems Biology, German Cancer Research Center, Heidelberg, Germany.,BioQuant Center, University of Heidelberg, Heidelberg, Germany
| | - Maximilian Hörner
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Julia Chalupsky
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany.,Center for Chronic Immunodeficiency, Medical Center Freiburg and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Maximilian Wess
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Simon M Brandl
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Robert W Smith
- Laboratory of Systems and Synthetic Biology, Wageningen University and Research, Wageningen, Netherlands
| | - Christian Fleck
- Laboratory of Systems and Synthetic Biology, Wageningen University and Research, Wageningen, Netherlands
| | - Tim Kunkel
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Matias D Zurbriggen
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany.,Institute of Synthetic Biology and Cluster of Excellence on Plant Sciences, University of Düsseldorf, Düsseldorf, Germany
| | - Thomas Höfer
- Division of Theoretical Systems Biology, German Cancer Research Center, Heidelberg, Germany.,BioQuant Center, University of Heidelberg, Heidelberg, Germany
| | - Wilfried Weber
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Wolfgang Wa Schamel
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany.,Laboratory of Systems and Synthetic Biology, Wageningen University and Research, Wageningen, Netherlands
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44
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Gálvez J, Gálvez JJ, García-Peñarrubia P. Is TCR/pMHC Affinity a Good Estimate of the T-cell Response? An Answer Based on Predictions From 12 Phenotypic Models. Front Immunol 2019; 10:349. [PMID: 30886616 PMCID: PMC6410681 DOI: 10.3389/fimmu.2019.00349] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 02/11/2019] [Indexed: 11/13/2022] Open
Abstract
On the T-cell surface the TCR is the only molecule that senses antigen, and the engagement of TCR with its specific antigenic peptide (agonist)/MHC complex (pMHC) is determined by the biochemical parameters of the TCR-pMHC interaction. This interaction is the keystone of the adaptive immune response by triggering intracellular signaling pathways that induce the expression of genes required for T cell-mediated effector functions, such as T cell proliferation, cytokine secretion and cytotoxicity. To study the TCR-pMHC interaction one of its properties most extensively analyzed has been TCR-pMHC affinity. However, and despite of intensive experimental research, the results obtained are far from conclusive. Here, to determine if TCR-pMHC affinity is a reliable parameter to characterize T-cell responses, a systematic study has been performed based on the predictions of 12 phenotypic models. This approach has the advantage that allow us to study the response of a given system as a function of only those parameters in which we are interested while other system parameters remain constant. A little surprising, only the simple occupancy model predicts a direct relationship between affinity and response so that an increase in affinity always leads to larger responses. Conversely, in the others more elaborate models this clear situation does not occur, i.e., that a general positive correlation between affinity and immune response does not exist. This is mainly because affinity values are given by the quotient k on/k off where k on and k off are the rate constants of the binding process (i.e., affinity is in fact the quotient of two parameters), so that different sets of these rate constants can give the same value of affinity. However, except in the occupancy model, the predicted T-cell responses depend on the individual values of k on and k off rather than on their quotient k on/k off. This allows: a) that systems with the same affinity can show quite different responses; and b) that systems with low affinity may exhibit larger responses than systems with higher affinities. This would make affinity a poor estimate of T-cell responses and, as a result, data correlations between affinity and immune response should be interpreted and used with caution.
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Affiliation(s)
- Jesús Gálvez
- Department of Physical Chemistry, Faculty of Chemistry, University of Murcia, Murcia, Spain
| | - Juan J Gálvez
- Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Pilar García-Peñarrubia
- Department of Biochemistry and Molecular Biology B and Immunology, School of Medicine, University of Murcia, Murcia, Spain
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45
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Baral S, Raja R, Sen P, Dixit NM. Towards multiscale modeling of the CD8 + T cell response to viral infections. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2019; 11:e1446. [PMID: 30811096 PMCID: PMC6614031 DOI: 10.1002/wsbm.1446] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 01/23/2019] [Accepted: 01/28/2019] [Indexed: 12/22/2022]
Abstract
The CD8+ T cell response is critical to the control of viral infections. Yet, defining the CD8+ T cell response to viral infections quantitatively has been a challenge. Following antigen recognition, which triggers an intracellular signaling cascade, CD8+ T cells can differentiate into effector cells, which proliferate rapidly and destroy infected cells. When the infection is cleared, they leave behind memory cells for quick recall following a second challenge. If the infection persists, the cells may become exhausted, retaining minimal control of the infection while preventing severe immunopathology. These activation, proliferation and differentiation processes as well as the mounting of the effector response are intrinsically multiscale and collective phenomena. Remarkable experimental advances in the recent years, especially at the single cell level, have enabled a quantitative characterization of several underlying processes. Simultaneously, sophisticated mathematical models have begun to be constructed that describe these multiscale phenomena, bringing us closer to a comprehensive description of the CD8+ T cell response to viral infections. Here, we review the advances made and summarize the challenges and opportunities ahead. This article is categorized under: Analytical and Computational Methods > Computational Methods Biological Mechanisms > Cell Fates Biological Mechanisms > Cell Signaling Models of Systems Properties and Processes > Mechanistic Models.
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Affiliation(s)
- Subhasish Baral
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, India
| | - Rubesh Raja
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, India
| | - Pramita Sen
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, India
| | - Narendra M Dixit
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, India.,Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore, India
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46
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Goyette J, Nieves DJ, Ma Y, Gaus K. How does T cell receptor clustering impact on signal transduction? J Cell Sci 2019; 132:132/4/jcs226423. [DOI: 10.1242/jcs.226423] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
ABSTRACT
The essential function of the T cell receptor (TCR) is to translate the engagement of peptides on the major histocompatibility complex (pMHC) into appropriate intracellular signals through the associated cluster of differentiation 3 (CD3) complex. The spatial organization of the TCR–CD3 complex in the membrane is thought to be a key regulatory element of signal transduction, raising the question of how receptor clustering impacts on TCR triggering. How signal transduction at the TCR–CD3 complex encodes the quality and quantity of pMHC molecules is not fully understood. This question can be approached by reconstituting T cell signaling in model and cell membranes and addressed by single-molecule imaging of endogenous proteins in T cells. We highlight such methods and further discuss how TCR clustering could affect pMHC rebinding rates, the local balance between kinase and phosphatase activity and/or the lipid environment to regulate the signal efficiency of the TCR–CD3 complex. We also examine whether clustering could affect the conformation of cytoplasmic CD3 tails through a biophysical mechanism. Taken together, we highlight how the spatial organization of the TCR–CD3 complex – addressed by reconstitution approaches – has emerged as a key regulatory element in signal transduction of this archetypal immune receptor.
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Affiliation(s)
- Jesse Goyette
- EMBL Australia Node in Single Molecule Science, University of New South Wales, Sydney 2052, Australia
- ARC Centre of Excellence in Advanced Molecular imaging, University of New South Wales, Sydney 2052, Australia
| | - Daniel J. Nieves
- EMBL Australia Node in Single Molecule Science, University of New South Wales, Sydney 2052, Australia
- ARC Centre of Excellence in Advanced Molecular imaging, University of New South Wales, Sydney 2052, Australia
| | - Yuanqing Ma
- EMBL Australia Node in Single Molecule Science, University of New South Wales, Sydney 2052, Australia
- ARC Centre of Excellence in Advanced Molecular imaging, University of New South Wales, Sydney 2052, Australia
| | - Katharina Gaus
- EMBL Australia Node in Single Molecule Science, University of New South Wales, Sydney 2052, Australia
- ARC Centre of Excellence in Advanced Molecular imaging, University of New South Wales, Sydney 2052, Australia
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47
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Lin JJY, Low-Nam ST, Alfieri KN, McAffee DB, Fay NC, Groves JT. Mapping the stochastic sequence of individual ligand-receptor binding events to cellular activation: T cells act on the rare events. Sci Signal 2019; 12:12/564/eaat8715. [PMID: 30647147 DOI: 10.1126/scisignal.aat8715] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
T cell receptor (TCR) binding to agonist peptide major histocompatibility complex (pMHC) triggers signaling events that initiate T cell responses. This system is remarkably sensitive, requiring only a few binding events to successfully activate a cellular response. On average, activating pMHC ligands exhibit mean dwell times of at least a few seconds when bound to the TCR. However, a T cell accumulates pMHC-TCR interactions as a stochastic series of discrete, single-molecule binding events whose individual dwell times are broadly distributed. With activation occurring in response to only a handful of such binding events, individual cells are unlikely to experience the average binding time. Here, we mapped the ensemble of pMHC-TCR binding events in space and time while simultaneously monitoring cellular activation. Our findings revealed that T cell activation hinges on rare, long-dwell time binding events that are an order of magnitude longer than the average agonist pMHC-TCR dwell time. Furthermore, we observed that short pMHC-TCR binding events that were spatially correlated and temporally sequential led to cellular activation. These observations indicate that T cell antigen discrimination likely occurs by sensing the tail end of the pMHC-TCR binding dwell time distribution rather than its average properties.
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Affiliation(s)
- Jenny J Y Lin
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Shalini T Low-Nam
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Katherine N Alfieri
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Darren B McAffee
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Nicole C Fay
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jay T Groves
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA.
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48
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Kotov DI, Pengo T, Mitchell JS, Gastinger MJ, Jenkins MK. Chrysalis: A New Method for High-Throughput Histo-Cytometry Analysis of Images and Movies. THE JOURNAL OF IMMUNOLOGY 2018; 202:300-308. [PMID: 30510065 DOI: 10.4049/jimmunol.1801202] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/02/2018] [Indexed: 12/17/2022]
Abstract
Advances in imaging have led to the development of powerful multispectral, quantitative imaging techniques, like histo-cytometry. The utility of this approach is limited, however, by the need for time consuming manual image analysis. We therefore developed the software Chrysalis and a group of Imaris Xtensions to automate this process. The resulting automation allowed for high-throughput histo-cytometry analysis of three-dimensional confocal microscopy and two-photon time-lapse images of T cell-dendritic cell interactions in mouse spleens. It was also applied to epi-fluorescence images to quantify T cell localization within splenic tissue by using a "signal absorption" strategy that avoids computationally intensive distance measurements. In summary, this image processing and analysis software makes histo-cytometry more useful for immunology applications by automating image analysis.
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Affiliation(s)
- Dmitri I Kotov
- Center for Immunology, University of Minnesota, Minneapolis, MN 55455; .,Department of Microbiology and Immunology, University of Minnesota, Minneapolis, MN 55455
| | - Thomas Pengo
- University of Minnesota Informatics Institute, University of Minnesota Twin Cities, Minneapolis, MN 55455
| | - Jason S Mitchell
- Center for Immunology, University of Minnesota, Minneapolis, MN 55455.,University Imaging Centers, University of Minnesota, Minneapolis, MN 55455.,Department of Medicine, University of Minnesota, Minneapolis, MN 55455; and
| | | | - Marc K Jenkins
- Center for Immunology, University of Minnesota, Minneapolis, MN 55455.,Department of Microbiology and Immunology, University of Minnesota, Minneapolis, MN 55455
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49
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Crooks JE, Boughter CT, Scott LR, Adams EJ. The Hypervariable Loops of Free TCRs Sample Multiple Distinct Metastable Conformations in Solution. Front Mol Biosci 2018; 5:95. [PMID: 30483515 PMCID: PMC6243104 DOI: 10.3389/fmolb.2018.00095] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 10/22/2018] [Indexed: 01/12/2023] Open
Abstract
CD4+ and CD8+ αβ T cell antigen recognition is determined by the interaction between the TCR Complementarity Determining Region (CDR) loops and the peptide-presenting MHC complex. These T cells are known for their ability to recognize multiple pMHC complexes, and for a necessary promiscuity that is required for their selection and function in the periphery. Crystallographic studies have previously elucidated the role of structural interactions in TCR engagement, but our understanding of the dynamic process that occurs during TCR binding is limited. To better understand the dynamic states that exist for TCR CDR loops in solution, and how this relates to their states when in complex with pMHC, we simulated the 2C T cell receptor in solution using all-atom molecular dynamics in explicit water and constructed a Markov State Model for each of the CDR3α and CDR3β loops. These models reveal multiple metastable states for the CDR3 loops in solution. Simulation data and metastable states reproduce known CDR3β crystal conformations, and reveal several novel conformations suggesting that CDR3β bound states are the result of search processes from nearby pre-existing equilibrium conformational states. Similar simulations of the invariant, Type I Natural Killer T cell receptor NKT15, which engages the monomorphic, MHC-like CD1d ligand, demonstrate that iNKT TCRs also have distinct states, but comparatively restricted degrees of motion.
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Affiliation(s)
- James E Crooks
- Graduate Program in Biophysical Sciences, University of Chicago, Chicago, IL, United States
| | - Christopher T Boughter
- Graduate Program in Biophysical Sciences, University of Chicago, Chicago, IL, United States
| | - L Ridgway Scott
- Department of Computer Science, University of Chicago, Chicago, IL, United States
| | - Erin J Adams
- Committee on Immunology University of Chicago, Chicago, IL, United States
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50
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Sibener LV, Fernandes RA, Kolawole EM, Carbone CB, Liu F, McAffee D, Birnbaum ME, Yang X, Su LF, Yu W, Dong S, Gee MH, Jude KM, Davis MM, Groves JT, Goddard WA, Heath JR, Evavold BD, Vale RD, Garcia KC. Isolation of a Structural Mechanism for Uncoupling T Cell Receptor Signaling from Peptide-MHC Binding. Cell 2018; 174:672-687.e27. [PMID: 30053426 PMCID: PMC6140336 DOI: 10.1016/j.cell.2018.06.017] [Citation(s) in RCA: 194] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 03/13/2018] [Accepted: 06/07/2018] [Indexed: 12/21/2022]
Abstract
TCR-signaling strength generally correlates with peptide-MHC binding affinity; however, exceptions exist. We find high-affinity, yet non-stimulatory, interactions occur with high frequency in the human T cell repertoire. Here, we studied human TCRs that are refractory to activation by pMHC ligands despite robust binding. Analysis of 3D affinity, 2D dwell time, and crystal structures of stimulatory versus non-stimulatory TCR-pMHC interactions failed to account for their different signaling outcomes. Using yeast pMHC display, we identified peptide agonists of a formerly non-responsive TCR. Single-molecule force measurements demonstrated the emergence of catch bonds in the activating TCR-pMHC interactions, correlating with exclusion of CD45 from the TCR-APC contact site. Molecular dynamics simulations of TCR-pMHC disengagement distinguished agonist from non-agonist ligands based on the acquisition of catch bonds within the TCR-pMHC interface. The isolation of catch bonds as a parameter mediating the coupling of TCR binding and signaling has important implications for TCR and antigen engineering for immunotherapy.
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Affiliation(s)
- Leah V Sibener
- Departments of Molecular and Cellular Physiology and Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Immunology Graduate Program, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Ricardo A Fernandes
- Departments of Molecular and Cellular Physiology and Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Elizabeth M Kolawole
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Catherine B Carbone
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Fan Liu
- Department of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Materials and Process Simulation Center, California Institute of Technology, Pasadena, CA 91125, USA; Institute for Systems Biology, Seattle, WA 98109, USA
| | - Darren McAffee
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Michael E Birnbaum
- Departments of Molecular and Cellular Physiology and Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Immunology Graduate Program, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Xinbo Yang
- Departments of Molecular and Cellular Physiology and Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Laura F Su
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Wong Yu
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Shen Dong
- Departments of Molecular and Cellular Physiology and Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Marvin H Gee
- Departments of Molecular and Cellular Physiology and Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Immunology Graduate Program, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Kevin M Jude
- Departments of Molecular and Cellular Physiology and Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Mark M Davis
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jay T Groves
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - William A Goddard
- Department of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Materials and Process Simulation Center, California Institute of Technology, Pasadena, CA 91125, USA
| | - James R Heath
- Institute for Systems Biology, Seattle, WA 98109, USA
| | - Brian D Evavold
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Ronald D Vale
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA; Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94143, USA
| | - K Christopher Garcia
- Departments of Molecular and Cellular Physiology and Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA.
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