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Padilla CM, Valenzi E, Tabib T, Nazari B, Sembrat J, Rojas M, Fuschiotti P, Lafyatis R. Increased CD8+ tissue resident memory T cells, regulatory T cells and activated natural killer cells in systemic sclerosis lungs. Rheumatology (Oxford) 2024; 63:837-845. [PMID: 37310903 PMCID: PMC10907815 DOI: 10.1093/rheumatology/kead273] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 05/10/2023] [Accepted: 05/15/2023] [Indexed: 06/15/2023] Open
Abstract
OBJECTIVE Multiple observations indicate a role for lymphocytes in driving autoimmunity in SSc. While T and NK cells have been studied in SSc whole blood and bronchoalveolar lavage fluid, their role remains unclear, partly because no studies have analysed these cell types in SSc-interstitial lung disease (ILD) lung tissue. This research aimed to identify and analyse the lymphoid subpopulations in SSc-ILD lung explants. METHODS Lymphoid populations from 13 SSc-ILD and 6 healthy control (HC) lung explants were analysed using Seurat following single-cell RNA sequencing. Lymphoid clusters were identified by their differential gene expression. Absolute cell numbers and cell proportions in each cluster were compared between cohorts. Additional analyses were performed using pathway analysis, pseudotime and cell ligand-receptor interactions. RESULTS Activated CD16+ NK cells, CD8+ tissue resident memory T cells and Treg cells were proportionately higher in SSc-ILD compared with HC lungs. Activated CD16+ NK cells in SSc-ILD showed upregulated granzyme B, IFN-γ and CD226. Amphiregulin, highly upregulated by NK cells, was predicted to interact with epidermal growth factor receptor on several bronchial epithelial cell populations. Shifts in CD8+ T cell populations indicated a transition from resting to effector to tissue resident phenotypes in SSc-ILD. CONCLUSIONS SSc-ILD lungs show activated lymphoid populations. Activated cytotoxic NK cells suggest they may kill alveolar epithelial cells, while their expression of amphiregulin suggests they may also induce bronchial epithelial cell hyperplasia. CD8+ T cells in SSc-ILD appear to transition from resting to the tissue resident memory phenotype.
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Affiliation(s)
- Cristina M Padilla
- Division of Rheumatology and Clinical Immunology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Eleanor Valenzi
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Tracy Tabib
- Division of Rheumatology and Clinical Immunology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Banafsheh Nazari
- Division of Rheumatology and Clinical Immunology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - John Sembrat
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Mauricio Rojas
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, Ohio State University College of Medicine, Columbus, OH, USA
| | - Patrizia Fuschiotti
- Division of Rheumatology and Clinical Immunology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Robert Lafyatis
- Division of Rheumatology and Clinical Immunology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Wang NI, Ninkov M, Haeryfar SMM. Classic costimulatory interactions in MAIT cell responses: from gene expression to immune regulation. Clin Exp Immunol 2023; 213:50-66. [PMID: 37279566 PMCID: PMC10324557 DOI: 10.1093/cei/uxad061] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 05/17/2023] [Accepted: 06/01/2023] [Indexed: 06/08/2023] Open
Abstract
Mucosa-associated invariant T (MAIT) cells are evolutionarily conserved, innate-like T lymphocytes with enormous immunomodulatory potentials. Due to their strategic localization, their invariant T cell receptor (iTCR) specificity for major histocompatibility complex-related protein 1 (MR1) ligands of commensal and pathogenic bacterial origin, and their sensitivity to infection-elicited cytokines, MAIT cells are best known for their antimicrobial characteristics. However, they are thought to also play important parts in the contexts of cancer, autoimmunity, vaccine-induced immunity, and tissue repair. While cognate MR1 ligands and cytokine cues govern MAIT cell maturation, polarization, and peripheral activation, other signal transduction pathways, including those mediated by costimulatory interactions, regulate MAIT cell responses. Activated MAIT cells exhibit cytolytic activities and secrete potent inflammatory cytokines of their own, thus transregulating the biological behaviors of several other cell types, including dendritic cells, macrophages, natural killer cells, conventional T cells, and B cells, with significant implications in health and disease. Therefore, an in-depth understanding of how costimulatory pathways control MAIT cell responses may introduce new targets for optimized MR1/MAIT cell-based interventions. Herein, we compare and contrast MAIT cells and mainstream T cells for their expression of classic costimulatory molecules belonging to the immunoglobulin superfamily and the tumor necrosis factor (TNF)/TNF receptor superfamily, based not only on the available literature but also on our transcriptomic analyses. We discuss how these molecules participate in MAIT cells' development and activities. Finally, we introduce several pressing questions vis-à-vis MAIT cell costimulation and offer new directions for future research in this area.
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Affiliation(s)
- Nicole I Wang
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | - Marina Ninkov
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | - S M Mansour Haeryfar
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
- Division of Clinical Immunology and Allergy, Department of Medicine, Western University, London, Ontario, Canada
- Division of General Surgery, Department of Surgery, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
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Qu L, Yin T, Zhao Y, Lv W, Liu Z, Chen C, Liu K, Shan S, Zhou R, Li X, Dong H. Histone demethylases in the regulation of immunity and inflammation. Cell Death Discov 2023; 9:188. [PMID: 37353521 DOI: 10.1038/s41420-023-01489-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/22/2023] [Accepted: 06/15/2023] [Indexed: 06/25/2023] Open
Abstract
Pathogens or danger signals trigger the immune response. Moderate immune response activation removes pathogens and avoids excessive inflammation and tissue damage. Histone demethylases (KDMs) regulate gene expression and play essential roles in numerous physiological processes by removing methyl groups from lysine residues on target proteins. Abnormal expression of KDMs is closely associated with the pathogenesis of various inflammatory diseases such as liver fibrosis, lung injury, and autoimmune diseases. Despite becoming exciting targets for diagnosing and treating these diseases, the role of these enzymes in the regulation of immune and inflammatory response is still unclear. Here, we review the underlying mechanisms through which KDMs regulate immune-related pathways and inflammatory responses. In addition, we also discuss the future applications of KDMs inhibitors in immune and inflammatory diseases.
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Affiliation(s)
- Lihua Qu
- Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei, China
- Department of Pathogenic Biology, School of Basic Medical Sciences, Wuhan University, Wuhan, Hubei, China
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, Xianning, Hubei, China
| | - Tong Yin
- Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei, China
- Department of Pathogenic Biology, School of Basic Medical Sciences, Wuhan University, Wuhan, Hubei, China
| | - Yijin Zhao
- Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei, China
- Department of Pathogenic Biology, School of Basic Medical Sciences, Wuhan University, Wuhan, Hubei, China
| | - Wenting Lv
- Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei, China
- Department of Pathogenic Biology, School of Basic Medical Sciences, Wuhan University, Wuhan, Hubei, China
| | - Ziqi Liu
- Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei, China
- Department of Pathogenic Biology, School of Basic Medical Sciences, Wuhan University, Wuhan, Hubei, China
| | - Chao Chen
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Kejun Liu
- Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei, China
- Department of Pathogenic Biology, School of Basic Medical Sciences, Wuhan University, Wuhan, Hubei, China
| | - Shigang Shan
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, Xianning, Hubei, China
| | - Rui Zhou
- Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei, China
- Department of Pathogenic Biology, School of Basic Medical Sciences, Wuhan University, Wuhan, Hubei, China
| | - Xiaoqing Li
- Biological Targeted Therapy Key Laboratory in Hubei, Huazhong University of Science and Technology, Wuhan, Hubei, China.
- Center for Stem Cell Research and Application, Union Hospital, Tongji Medical School, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| | - Huifen Dong
- Hubei Province Key Laboratory of Allergy and Immunology, Wuhan University, Wuhan, Hubei, China.
- Department of Pathogenic Biology, School of Basic Medical Sciences, Wuhan University, Wuhan, Hubei, China.
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Labuz D, Cacioppo J, Li K, Aubé J, Leung DT. Enhancing Mucosal-Associated Invariant T Cell Function and Expansion with Human Selective Serum. Immunohorizons 2023; 7:116-124. [PMID: 36651819 PMCID: PMC10026854 DOI: 10.4049/immunohorizons.2200082] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 12/26/2022] [Indexed: 01/19/2023] Open
Abstract
Mucosal-associated invariant T (MAIT) cells are promising innate-like lymphocytes with potential for use in anti-tumor immunotherapy. Existing MAIT cell expansion protocols are associated with potentially decremental phenotypic changes, including increased frequency of CD4+ MAIT cells and higher inhibitory receptor expression. In this study, we compared the effect on expansion of human MAIT cells of a serum replacement, Physiologix XF SR (Phx), with traditional serum FBS for supplementing RPMI 1640 media. Using flow cytometry, we found that Phx supported a significantly higher proliferative capacity for MAIT cells and resulted in a lower frequency of CD4+ MAIT cells, which have been associated with reduced Th1 effector and cytolytic functions. We saw that culturing MAIT cells in Phx led to better survival of MAIT cells and lower frequency of PD-1+ MAIT cells than FBS-supplemented media. Functionally, we saw that Phx supplementation was associated with a higher frequency of IFN-γ+ MAIT cells after stimulation with Escherichia coli than FBS-supplemented RPMI. In conclusion, we show that MAIT cells cultured in Phx have higher proliferative capacity, lower expression of inhibitory receptors, and higher capacity to produce IFN-γ after E. coli stimulation than FBS-supplemented RPMI. This work shows that expanding MAIT cells with Phx compared with FBS-supplemented RPMI results in a more functionally desirable MAIT cell for future anti-tumor immunotherapy.
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Affiliation(s)
- Daniel Labuz
- Division of Infectious Disease, Department of Internal Medicine, University of Utah, Salt Lake City, UT
- Division of Microbiology & Immunology, Department of Pathology, University of Utah, Salt Lake City, UT
| | - Jackson Cacioppo
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Kelin Li
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Jeffrey Aubé
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Daniel T. Leung
- Division of Infectious Disease, Department of Internal Medicine, University of Utah, Salt Lake City, UT
- Division of Microbiology & Immunology, Department of Pathology, University of Utah, Salt Lake City, UT
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Jakob J, Kröger A, Klawonn F, Bruder D, Jänsch L. Translatome analyses by bio-orthogonal non-canonical amino acid labeling reveal that MR1-activated MAIT cells induce an M1 phenotype and antiviral programming in antigen-presenting monocytes. Front Immunol 2023; 14:1091837. [PMID: 36875139 PMCID: PMC9977998 DOI: 10.3389/fimmu.2023.1091837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 01/30/2023] [Indexed: 02/18/2023] Open
Abstract
MAIT cells are multifunctional innate-like effector cells recognizing bacterial-derived vitamin B metabolites presented by the non-polymorphic MHC class I related protein 1 (MR1). However, our understanding of MR1-mediated responses of MAIT cells upon their interaction with other immune cells is still incomplete. Here, we performed the first translatome study of primary human MAIT cells interacting with THP-1 monocytes in a bicellular system. We analyzed the interaction between MAIT and THP-1 cells in the presence of the activating 5-OP-RU or the inhibitory Ac-6-FP MR1-ligand. Using bio-orthogonal non-canonical amino acid tagging (BONCAT) we were able to enrich selectively those proteins that were newly translated during MR1-dependent cellular interaction. Subsequently, newly translated proteins were measured cell-type-specifically by ultrasensitive proteomics to decipher the coinciding immune responses in both cell types. This strategy identified over 2,000 MAIT and 3,000 THP-1 active protein translations following MR1 ligand stimulations. Translation in both cell types was found to be increased by 5-OP-RU, which correlated with their conjugation frequency and CD3 polarization at MAIT cell immunological synapses in the presence of 5-OP-RU. In contrast, Ac-6-FP only regulated a few protein translations, including GSK3B, indicating an anergic phenotype. In addition to known effector responses, 5-OP-RU-induced protein translations uncovered type I and type II Interferon-driven protein expression profiles in both MAIT and THP-1 cells. Interestingly, the translatome of THP-1 cells suggested that activated MAIT cells can impact M1/M2 polarization in these cells. Indeed, gene and surface expression of CXCL10, IL-1β, CD80, and CD206 confirmed an M1-like phenotype of macrophages being induced in the presence of 5-OP-RU-activated MAIT cells. Furthermore, we validated that the Interferon-driven translatome was accompanied by the induction of an antiviral phenotype in THP-1 cells, which were found able to suppress viral replication following conjugation with MR1-activated MAIT cells. In conclusion, BONCAT translatomics extended our knowledge of MAIT cell immune responses at the protein level and discovered that MR1-activated MAIT cells are sufficient to induce M1 polarization and an anti-viral program of macrophages.
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Affiliation(s)
- Josefine Jakob
- Cellular Proteomics, Helmholtz Centre for Infection Research, Braunschweig, Germany.,Institute of Medical Microbiology and Hospital Hygiene, Infection Immunology, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg, Magdeburg, Germany.,Immune Regulation, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Andrea Kröger
- Innate Immunity and Infection, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany.,Institute of Medical Microbiology and Hospital Hygiene, Molecular Microbiology, Health Campus Immunology, Infectiology and Inflammation, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Frank Klawonn
- Cellular Proteomics, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Dunja Bruder
- Institute of Medical Microbiology and Hospital Hygiene, Infection Immunology, Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke University Magdeburg, Magdeburg, Germany.,Immune Regulation, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Lothar Jänsch
- Cellular Proteomics, Helmholtz Centre for Infection Research, Braunschweig, Germany
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Zhang H, Hu Y, Liu D, Liu Z, Xie N, Liu S, Zhang J, Jiang Y, Li C, Wang Q, Chen X, Ye D, Sun D, Zhai Y, Yan X, Liu Y, Chen CD, Huang X, Eugene Chin Y, Shi Y, Wu B, Zhang X. The histone demethylase Kdm6b regulates the maturation and cytotoxicity of TCRαβ+CD8αα+ intestinal intraepithelial lymphocytes. Cell Death Differ 2022; 29:1349-1363. [PMID: 34999729 PMCID: PMC9287323 DOI: 10.1038/s41418-021-00921-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 11/30/2021] [Accepted: 12/02/2021] [Indexed: 12/22/2022] Open
Abstract
AbstractIntestinal intraepithelial lymphocytes (IELs) are distributed along the length of the intestine and are considered the frontline of immune surveillance. The precise molecular mechanisms, especially epigenetic regulation, of their development and function are poorly understood. The trimethylation of histone 3 at lysine 27 (H3K27Me3) is a kind of histone modifications and associated with gene repression. Kdm6b is an epigenetic enzyme responsible for the demethylation of H3K27Me3 and thus promotes gene expression. Here we identified Kdm6b as an important intracellular regulator of small intestinal IELs. Mice genetically deficient for Kdm6b showed greatly reduced numbers of TCRαβ+CD8αα+ IELs. In the absence of Kdm6b, TCRαβ+CD8αα+ IELs exhibited increased apoptosis, disturbed maturation and a compromised capability to lyse target cells. Both IL-15 and Kdm6b-mediated demethylation of histone 3 at lysine 27 are responsible for the maturation of TCRαβ+CD8αα+ IELs through upregulating the expression of Gzmb and Fasl. In addition, Kdm6b also regulates the expression of the gut-homing molecule CCR9 by controlling H3K27Me3 level at its promoter. However, Kdm6b is dispensable for the reactivity of thymic precursors of TCRαβ+CD8αα+ IELs (IELPs) to IL-15 and TGF-β. In conclusion, we showed that Kdm6b plays critical roles in the maturation and cytotoxic function of small intestinal TCRαβ+CD8αα+ IELs.
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7
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Guo L, Chen S, Ou L, Li S, Ye ZN, Liu HF. Disrupted Alpha-Ketoglutarate Homeostasis: Understanding Kidney Diseases from the View of Metabolism and Beyond. Diabetes Metab Syndr Obes 2022; 15:1961-1974. [PMID: 35783031 PMCID: PMC9248815 DOI: 10.2147/dmso.s369090] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/17/2022] [Indexed: 11/26/2022] Open
Abstract
Alpha-ketoglutarate (AKG) is a key intermediate of various metabolic pathways including tricarboxylic acid (TCA) cycle, anabolic and catabolic reactions of amino acids, and collagen biosynthesis. Meanwhile, AKG also participates in multiple signaling pathways related to cellular redox regulation, epigenetic processes, and inflammation response. Emerging evidence has shown that kidney diseases like diabetic nephropathy and renal ischemia/reperfusion injury are associated with metabolic disorders. In consistence with metabolic role of AKG, further metabolomics study demonstrated a dysregulated AKG level in kidney diseases. Intriguingly, earlier studies during the years of 1980s and 1990s indicated that AKG may benefit wound healing and surgery recovery. Recently, interests on AKG are arising again due to its protective roles on healthy ageing, which may shed light on developing novel therapeutic strategies against age-related diseases including renal diseases. This review will summarize the physiological and pathological properties of AKG, as well as the underlying molecular mechanisms, with a special emphasis on kidney diseases.
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Affiliation(s)
- Lijing Guo
- Guangdong Provincial Key Laboratory of Autophagy and Major Chronic Non-Communicable Diseases, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China
- Institute of Nephrology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China
| | - Shihua Chen
- Guangdong Provincial Key Laboratory of Autophagy and Major Chronic Non-Communicable Diseases, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China
- Institute of Nephrology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China
| | - Liping Ou
- Guangdong Provincial Key Laboratory of Autophagy and Major Chronic Non-Communicable Diseases, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China
- Institute of Nephrology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China
| | - Shangmei Li
- Guangdong Provincial Key Laboratory of Autophagy and Major Chronic Non-Communicable Diseases, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China
| | - Zhen-Nan Ye
- Guangdong Provincial Key Laboratory of Autophagy and Major Chronic Non-Communicable Diseases, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China
- Institute of Nephrology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China
- Correspondence: Zhen-Nan Ye; Hua-Feng Liu, Email ;
| | - Hua-Feng Liu
- Guangdong Provincial Key Laboratory of Autophagy and Major Chronic Non-Communicable Diseases, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China
- Institute of Nephrology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524001, People’s Republic of China
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Mak JYW, Liu L, Fairlie DP. Chemical Modulators of Mucosal Associated Invariant T Cells. Acc Chem Res 2021; 54:3462-3475. [PMID: 34415738 DOI: 10.1021/acs.accounts.1c00359] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Over the past decade, we have contributed to the chemistry of microbial natural products and synthetic ligands, related to riboflavin and uracils, that modulate immune cells called mucosal associated invariant T cells (MAIT cells). These highly abundant T lymphocytes were only discovered in 2003 and have become recognized for their importance in mammalian immunology. Unlike other T cells, MAIT cells are not activated by peptide or lipid antigens. In collaboration with immunology and structural biology research groups, we discovered that they are instead activated by unstable nitrogen-containing heterocycles synthesized by bacteria. The most potent naturally occurring activating compound (antigen) is 5-(2-oxopropylideneamino)-d-ribitylaminouracil (5-OP-RU). This compound is an imine (Schiff base) formed through condensation between an intermediate in the biosynthesis of riboflavin (vitamin B2) and a metabolic byproduct of mammalian and microbial glycolysis. Although it is very unstable in water due to intramolecular ring closure or hydrolysis, we were able to develop a non-enzymatic synthesis that yields a pure kinetically stable compound in a nonaqueous solvent. This compound has revolutionized the study of MAIT cell immunology due to its potent activation (EC50 = 2 pM) of MAIT cells and its development into immunological reagents for detecting and characterizing MAIT cells in tissues. MAIT cells are now linked to key physiological processes and disease, including antibacterial defense, tissue repair, regulation of graft-vs-host disease, gastritis, inflammatory bowel diseases, and cancer. 5-OP-RU activates MAIT cells and, like a vaccine, has been shown to protect mice from bacterial infections and cancers. Mechanistic studies on the binding of 5-OP-RU to its dual protein targets, the major histocompatibility complex class I related protein (MR1) and the MAIT cell receptor (MAIT TCR), have involved synthetic chemistry, 2D 1H NMR spectroscopy, mass spectrometry, computer modeling and molecular dynamics simulations, biochemical, cellular, and immunological assays, and protein structural biology. These combined studies have revealed structural influences for 5-OP-RU in solution on protein binding and antigen presentation and potency; informed the development of potent (EC50 = 2 nM) and water stable analogues; led to fluorescent analogues for detecting and tracking binding proteins in and on cells; and enabled discovery of drugs and drug-like molecules that bind MR1 and modulate MAIT cell function. MAIT cells offer new opportunities for chemical synthesis to enhance the stability, potency, selectivity, and bioavailability of small molecule ligands for MR1 or MAIT TCR proteins, and to contribute to the understanding of T cell immunity and the development of prospective new immunomodulating medicines.
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Affiliation(s)
- Jeffrey Y. W. Mak
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
- Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of QueenslandBrisbane, Queensland 4072, Australia
| | - Ligong Liu
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
- Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of QueenslandBrisbane, Queensland 4072, Australia
| | - David P. Fairlie
- Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
- Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of QueenslandBrisbane, Queensland 4072, Australia
- Centre for Inflammation and Disease Research, Institute for Molecular Bioscience, The University of QueenslandBrisbane, Queensland 4072, Australia
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