RESUMO
The Major Histocompatibility Complex (MHC) locus encodes classical MHC class I and MHC class II molecules and nonclassical MHC-I molecules. The architecture of these molecules is ideally suited to capture and present an array of peptide antigens (Ags). In addition, the CD1 family members and MR1 are MHC class I-like molecules that bind lipid-based Ags and vitamin B precursors, respectively. These Ag-bound molecules are subsequently recognized by T cell antigen receptors (TCRs) expressed on the surface of T lymphocytes. Structural and associated functional studies have been highly informative in providing insight into these interactions, which are crucial to immunity, and how they can lead to aberrant T cell reactivity. Investigators have determined over thirty unique TCR-peptide-MHC-I complex structures and twenty unique TCR-peptide-MHC-II complex structures. These investigations have shown a broad consensus in docking geometry and provided insight into MHC restriction. Structural studies on TCR-mediated recognition of lipid and metabolite Ags have been mostly confined to TCRs from innate-like natural killer T cells and mucosal-associated invariant T cells, respectively. These studies revealed clear differences between TCR-lipid-CD1, TCR-metabolite-MR1, and TCR-peptide-MHC recognition. Accordingly, TCRs show remarkable structural and biological versatility in engaging different classes of Ag that are presented by polymorphic and monomorphic Ag-presenting molecules of the immune system.
Assuntos
Apresentação de Antígeno , Antígenos/imunologia , Antígenos/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Animais , Antígenos/química , Reações Cruzadas/imunologia , Antígenos de Histocompatibilidade Classe I/química , Antígenos de Histocompatibilidade Classe I/genética , Antígenos de Histocompatibilidade Classe I/metabolismo , Antígenos de Histocompatibilidade Classe II/química , Antígenos de Histocompatibilidade Classe II/genética , Antígenos de Histocompatibilidade Classe II/imunologia , Humanos , Lipídeos/imunologia , Ligação Proteica/imunologia , Receptores de Antígenos de Linfócitos T/químicaRESUMO
Butyrophilin (BTN) molecules are emerging as key regulators of T cell immunity; however, how they trigger cell-mediated responses is poorly understood. Here, the crystal structure of a gamma-delta T cell antigen receptor (γδTCR) in complex with BTN2A1 revealed that BTN2A1 engages the side of the γδTCR, leaving the apical TCR surface bioavailable. We reveal that a second γδTCR ligand co-engages γδTCR via binding to this accessible apical surface in a BTN3A1-dependent manner. BTN2A1 and BTN3A1 also directly interact with each other in cis, and structural analysis revealed formation of W-shaped heteromeric multimers. This BTN2A1-BTN3A1 interaction involved the same epitopes that BTN2A1 and BTN3A1 each use to mediate the γδTCR interaction; indeed, locking BTN2A1 and BTN3A1 together abrogated their interaction with γδTCR, supporting a model wherein the two γδTCR ligand-binding sites depend on accessibility to cryptic BTN epitopes. Our findings reveal a new paradigm in immune activation, whereby γδTCRs sense dual epitopes on BTN complexes.
Assuntos
Butirofilinas , Receptores de Antígenos de Linfócitos T gama-delta , Butirofilinas/metabolismo , Butirofilinas/imunologia , Butirofilinas/química , Receptores de Antígenos de Linfócitos T gama-delta/imunologia , Receptores de Antígenos de Linfócitos T gama-delta/metabolismo , Humanos , Ligação Proteica , Multimerização Proteica , Antígenos CD/metabolismo , Antígenos CD/imunologia , Antígenos CD/química , Linfócitos T/imunologia , Linfócitos T/metabolismo , Cristalografia por Raios X , Ativação Linfocitária/imunologia , Modelos Moleculares , Linfócitos Intraepiteliais/imunologia , Linfócitos Intraepiteliais/metabolismoRESUMO
CD8+ T cells provide robust antiviral immunity, but how epitope-specific T cells evolve across the human lifespan is unclear. Here we defined CD8+ T cell immunity directed at the prominent influenza epitope HLA-A*02:01-M158-66 (A2/M158) across four age groups at phenotypic, transcriptomic, clonal and functional levels. We identify a linear differentiation trajectory from newborns to children then adults, followed by divergence and a clonal reset in older adults. Gene profiles in older adults closely resemble those of newborns and children, despite being clonally distinct. Only child-derived and adult-derived A2/M158+CD8+ T cells had the potential to differentiate into highly cytotoxic epitope-specific CD8+ T cells, which was linked to highly functional public T cell receptor (TCR)αß signatures. Suboptimal TCRαß signatures in older adults led to less proliferation, polyfunctionality, avidity and recognition of peptide mutants, although displayed no signs of exhaustion. These data suggest that priming T cells at different stages of life might greatly affect CD8+ T cell responses toward viral infections.
Assuntos
Linfócitos T CD8-Positivos , Longevidade , Recém-Nascido , Humanos , Idoso , Epitopos de Linfócito T/genética , Linfócitos T Citotóxicos , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Receptores de Antígenos de Linfócitos T/genéticaRESUMO
In recent years, a population of unconventional T cells called 'mucosal-associated invariant T cells' (MAIT cells) has captured the attention of immunologists and clinicians due to their abundance in humans, their involvement in a broad range of infectious and non-infectious diseases and their unusual specificity for microbial riboflavin-derivative antigens presented by the major histocompatibility complex (MHC) class I-like protein MR1. MAIT cells use a limited T cell antigen receptor (TCR) repertoire with public antigen specificities that are conserved across species. They can be activated by TCR-dependent and TCR-independent mechanisms and exhibit rapid, innate-like effector responses. Here we review evidence showing that MAIT cells are a key component of the immune system and discuss their basic biology, development, role in disease and immunotherapeutic potential.
Assuntos
Apresentação de Antígeno/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Antígenos de Histocompatibilidade Menor/imunologia , Células T Invariantes Associadas à Mucosa/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Animais , Antígenos/imunologia , Suscetibilidade a Doenças/imunologia , Humanos , Ativação Linfocitária/imunologia , Camundongos , Neoplasias/imunologiaRESUMO
In the version of this article initially published, three authors (Hui-Fern Kuoy, Adam P. Uldrich and Dale. I. Godfrey) and their affiliations, acknowledgments and contributions were not included. The correct information is as follows:Ayano C. Kohlgruber1,2, Shani T. Gal-Oz3, Nelson M. LaMarche1,2, Moto Shimazaki1, Danielle Duquette4, Hui-Fern Koay5,6, Hung N. Nguyen1, Amir I. Mina4, Tyler Paras1, Ali Tavakkoli7, Ulrich von Andrian2,8, Adam P. Uldrich5,6, Dale I. Godfrey5,6, Alexander S. Banks4, Tal Shay3, Michael B. Brenner1,10* and Lydia Lynch1,4,9,10*1Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA, USA. 2Division of Medical Sciences, Harvard Medical School, Boston, MA, USA. 3Department of Life Sciences, Ben-Gurion University of the Negev, Beersheba, Israel. 4Division of Endocrinology, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA. 5Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Australia. 6ARC Centre of Excellence in Advanced Molecular Imaging, University of Melbourne, Parkville, Australia. 7Department of General and Gastrointestinal Surgery, Brigham and Women's Hospital, Boston, MA, USA. 8Department of Microbiology and Immunology, Harvard Medical School, Boston, MA, USA. 9School of Biochemistry and Immunology, Trinity College, Dublin, Ireland. 10These authors jointly supervised this work: Michael B. Brenner, Lydia Lynch. *e-mail: mbrenner@research.bwh.harvard.edu; llynch@bwh.harvard.eduAcknowledgementsWe thank A.T. Chicoine, flow cytometry core manager at the Human Immunology Center at BWH, for flow cytometry sorting. We thank D. Sant'Angelo (Rutgers Cancer Institute) for providing Zbtb16-/- mice and R. O'Brien (National Jewish Health) for providing Vg4/6-/- mice. Supported by NIH grant R01 AI11304603 (to M.B.B.), ERC Starting Grant 679173 (to L.L.), the National Health and Medical Research Council of Australia (1013667), an Australian Research Council Future Fellowship (FT140100278 for A.P.U.) and a National Health and Medical Research Council of Australia Senior Principal Research Fellowship (1117766 for D.I.G.).Author contributionsA.C.K., L.L., and M.B.B. conceived and designed the experiments, and wrote the manuscript. A.C.K., N.M.L., L.L., H.N.N., M.S., T.P., and D.D. performed the experiments. S.T.G.-O. and T.S. performed the RNA-seq analysis. A.S.B. and A.I.M. provided advice and performed the CLAMS experiments. A.T. provided human bariatric patient samples. Parabiosis experiments were performed in the laboratory of U.v.A. H.-F.K., A.P.U. and D.I.G provided critical insight into the TCR chain usage of PLZF+ γδ T cells. M.B.B., N.M.L., and L.L. critically reviewed the manuscript.The errors have been corrected in the HTML and PDF version of the article.Correction to: Nature Immunology doi:10.1038/s41590-018-0094-2 (2018), published online 18 April 2018.
RESUMO
γδ T cells are situated at barrier sites and guard the body from infection and damage. However, little is known about their roles outside of host defense in nonbarrier tissues. Here, we characterize a highly enriched tissue-resident population of γδ T cells in adipose tissue that regulate age-dependent regulatory T cell (Treg) expansion and control core body temperature in response to environmental fluctuations. Mechanistically, innate PLZF+ γδ T cells produced tumor necrosis factor and interleukin (IL) 17 A and determined PDGFRα+ and Pdpn+ stromal-cell production of IL-33 in adipose tissue. Mice lacking γδ T cells or IL-17A exhibited decreases in both ST2+ Treg cells and IL-33 abundance in visceral adipose tissue. Remarkably, these mice also lacked the ability to regulate core body temperature at thermoneutrality and after cold challenge. Together, these findings uncover important physiological roles for resident γδ T cells in adipose tissue immune homeostasis and body-temperature control.
Assuntos
Tecido Adiposo/citologia , Homeostase/fisiologia , Interleucina-17/metabolismo , Linfócitos T Reguladores/fisiologia , Termogênese/fisiologia , Tecido Adiposo/fisiologia , Animais , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores de Antígenos de Linfócitos T gama-delta , Subpopulações de Linfócitos T/fisiologiaRESUMO
The hallmark function of αß T cell antigen receptors (TCRs) involves the highly specific co-recognition of a major histocompatibility complex molecule and its carried peptide. However, the molecular basis of the interactions of TCRs with the lipid antigen-presenting molecule CD1c is unknown. We identified frequent staining of human T cells with CD1c tetramers across numerous subjects. Whereas TCRs typically show high specificity for antigen, both tetramer binding and autoreactivity occurred with CD1c in complex with numerous, chemically diverse self lipids. Such extreme polyspecificity was attributable to binding of the TCR over the closed surface of CD1c, with the TCR covering the portal where lipids normally protrude. The TCR essentially failed to contact lipids because they were fully seated within CD1c. These data demonstrate the sequestration of lipids within CD1c as a mechanism of autoreactivity and point to small lipid size as a determinant of autoreactive T cell responses.
Assuntos
Antígenos CD1/imunologia , Autoantígenos/imunologia , Autoimunidade/imunologia , Glicoproteínas/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Linfócitos T/imunologia , Apresentação de Antígeno/imunologia , Humanos , Lipídeos/imunologia , Ativação Linfocitária/imunologiaRESUMO
The major-histocompatibility-complex-(MHC)-class-I-related molecule MR1 can present activating and non-activating vitamin-B-based ligands to mucosal-associated invariant T cells (MAIT cells). Whether MR1 binds other ligands is unknown. Here we identified a range of small organic molecules, drugs, drug metabolites and drug-like molecules, including salicylates and diclofenac, as MR1-binding ligands. Some of these ligands inhibited MAIT cells ex vivo and in vivo, while others, including diclofenac metabolites, were agonists. Crystal structures of a T cell antigen receptor (TCR) from a MAIT cell in complex with MR1 bound to the non-stimulatory and stimulatory compounds showed distinct ligand orientations and contacts within MR1, which highlighted the versatility of the MR1 binding pocket. The findings demonstrated that MR1 was able to capture chemically diverse structures, spanning mono- and bicyclic compounds, that either inhibited or activated MAIT cells. This indicated that drugs and drug-like molecules can modulate MAIT cell function in mammals.
Assuntos
Antígenos de Histocompatibilidade Classe I/metabolismo , Antígenos de Histocompatibilidade Menor/metabolismo , Células T Invariantes Associadas à Mucosa/efeitos dos fármacos , Células T Invariantes Associadas à Mucosa/metabolismo , Sítios de Ligação , Linhagem Celular , Cristalografia por Raios X , Descoberta de Drogas , Antígenos de Histocompatibilidade Classe I/química , Humanos , Ligação de Hidrogênio , Ligantes , Ativação Linfocitária/efeitos dos fármacos , Ativação Linfocitária/imunologia , Antígenos de Histocompatibilidade Menor/química , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , Células T Invariantes Associadas à Mucosa/imunologia , Ligação Proteica , Receptores de Antígenos de Linfócitos T/química , Receptores de Antígenos de Linfócitos T/metabolismo , Relação Estrutura-AtividadeRESUMO
Mucosal-associated invariant T cells (MAIT cells) detect microbial vitamin B2 derivatives presented by the antigen-presenting molecule MR1. Here we defined three developmental stages and checkpoints for the MAIT cell lineage in humans and mice. Stage 1 and stage 2 MAIT cells predominated in thymus, while stage 3 cells progressively increased in abundance extrathymically. Transition through each checkpoint was regulated by MR1, whereas the final checkpoint that generated mature functional MAIT cells was controlled by multiple factors, including the transcription factor PLZF and microbial colonization. Furthermore, stage 3 MAIT cell populations were expanded in mice deficient in the antigen-presenting molecule CD1d, suggestive of a niche shared by MAIT cells and natural killer T cells (NKT cells). Accordingly, this study maps the developmental pathway and checkpoints that control the generation of functional MAIT cells.
Assuntos
Diferenciação Celular/imunologia , Células T Invariantes Associadas à Mucosa/citologia , Células T Invariantes Associadas à Mucosa/fisiologia , Timo/imunologia , Timo/metabolismo , Animais , Antígenos CD1d/genética , Biomarcadores , Diferenciação Celular/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Humanos , Imunofenotipagem , Células Progenitoras Linfoides/imunologia , Células Progenitoras Linfoides/metabolismo , Masculino , Camundongos , Camundongos Knockout , MicroRNAs/genéticaRESUMO
While most studies of T lymphocytes have focused on T cells reactive to complexes of peptide and major histocompatibility complex (MHC) proteins, many other types of T cells do not fit this paradigm. These include CD1-restricted T cells, MR1-restricted mucosal associated invariant T cells (MAIT cells), MHC class Ib-reactive T cells, and γδ T cells. Collectively, these T cells are considered 'unconventional', in part because they can recognize lipids, small-molecule metabolites and specially modified peptides. Unlike MHC-reactive T cells, these apparently disparate T cell types generally show simplified patterns of T cell antigen receptor (TCR) expression, rapid effector responses and 'public' antigen specificities. Here we review evidence showing that unconventional T cells are an abundant component of the human immune system and discuss the immunotherapeutic potential of these cells and their antigenic targets.
Assuntos
Subpopulações de Linfócitos T/imunologia , Animais , Apresentação de Antígeno , Antígenos CD1/química , Antígenos CD1/metabolismo , Antígenos de Histocompatibilidade Classe I/química , Antígenos de Histocompatibilidade Classe I/metabolismo , Humanos , Camundongos , Modelos Imunológicos , Estrutura Molecular , Células T Matadoras Naturais/imunologia , Receptores de Antígenos de Linfócitos T/metabolismoRESUMO
Invariant natural killer T cells (iNKT cells) are lipid-sensing innate T cells that are restricted by the antigen-presenting molecule CD1d and express the transcription factor PLZF. iNKT cells accumulate in adipose tissue, where they are anti-inflammatory, but the factors that contribute to their anti-inflammatory nature, as well as their targets in adipose tissue, are unknown. Here we found that iNKT cells in adipose tissue had a unique transcriptional program and produced interleukin 2 (IL-2) and IL-10. Unlike other iNKT cells, they lacked PLZF but expressed the transcription factor E4BP4, which controlled their IL-10 production. The adipose iNKT cells were a tissue-resident population that induced an anti-inflammatory phenotype in macrophages and, through the production of IL-2, controlled the number, proliferation and suppressor function of regulatory T cells (Treg cells) in adipose tissue. Thus, iNKT cells in adipose tissue are unique regulators of immunological homeostasis in this tissue.
Assuntos
Tecido Adiposo/imunologia , Fatores de Transcrição Kruppel-Like/biossíntese , Macrófagos/imunologia , Células T Matadoras Naturais/metabolismo , Linfócitos T Reguladores/metabolismo , Tecido Adiposo/citologia , Animais , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/imunologia , Processos de Crescimento Celular/imunologia , Feminino , Citometria de Fluxo , Regulação da Expressão Gênica , Homeostase/imunologia , Interleucina-10/genética , Interleucina-10/imunologia , Interleucina-2/genética , Interleucina-2/imunologia , Fatores de Transcrição Kruppel-Like/deficiência , Fatores de Transcrição Kruppel-Like/genética , Fatores de Transcrição Kruppel-Like/imunologia , Macrófagos/citologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Células T Matadoras Naturais/citologia , Células T Matadoras Naturais/imunologia , Proteína com Dedos de Zinco da Leucemia Promielocítica , Organismos Livres de Patógenos Específicos , Linfócitos T Reguladores/citologia , Linfócitos T Reguladores/imunologiaRESUMO
A central paradigm in αß T cell-mediated immunity is the simultaneous co-recognition of antigens and antigen-presenting molecules by the αß T cell antigen receptor (TCR). CD1a presents a broad repertoire of lipid-based antigens. We found that a prototypical autoreactive TCR bound CD1a when it was presenting a series of permissive endogenous ligands, while other lipid ligands were nonpermissive to TCR binding. The structures of two TCR-CD1a-lipid complexes showed that the TCR docked over the A' roof of CD1a in a manner that precluded direct contact with permissive ligands. Nonpermissive ligands indirectly inhibited TCR binding by disrupting the TCR-CD1a contact zone. The exclusive recognition of CD1a by the TCR represents a previously unknown mechanism whereby αß T cells indirectly sense self antigens that are bound to an antigen-presenting molecule.
Assuntos
Apresentação de Antígeno/imunologia , Antígenos CD1/imunologia , Autoantígenos/imunologia , Lipídeos/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Linfócitos T/imunologia , Linhagem Celular , Linhagem Celular Tumoral , Células HEK293 , Humanos , Células Jurkat , Ligantes , Ligação ProteicaRESUMO
Central to adaptive immunity is the interaction between the αß T cell receptor (TCR) and peptide presented by the major histocompatibility complex (MHC) molecule. Presumably reflecting TCR-MHC bias and T cell signaling constraints, the TCR universally adopts a canonical polarity atop the MHC. We report the structures of two TCRs, derived from human induced T regulatory (iT(reg)) cells, complexed to an MHC class II molecule presenting a proinsulin-derived peptide. The ternary complexes revealed a 180° polarity reversal compared to all other TCR-peptide-MHC complex structures. Namely, the iT(reg) TCR α-chain and ß-chain are overlaid with the α-chain and ß-chain of MHC class II, respectively. Nevertheless, this TCR interaction elicited a peptide-reactive, MHC-restricted T cell signal. Thus TCRs are not 'hardwired' to interact with MHC molecules in a stereotypic manner to elicit a T cell signal, a finding that fundamentally challenges our understanding of TCR recognition.
Assuntos
Autoantígenos/metabolismo , Complexo Principal de Histocompatibilidade/imunologia , Receptores de Antígenos de Linfócitos T/metabolismo , Imunidade Adaptativa , Apresentação de Antígeno , Autoantígenos/química , Autoantígenos/genética , Células Cultivadas , Antígeno HLA-DR4/química , Antígeno HLA-DR4/genética , Antígeno HLA-DR4/metabolismo , Antígenos de Histocompatibilidade Classe II/química , Antígenos de Histocompatibilidade Classe II/genética , Antígenos de Histocompatibilidade Classe II/metabolismo , Humanos , Complexo Principal de Histocompatibilidade/genética , Modelos Moleculares , Mutagênese Sítio-Dirigida , Proinsulina/química , Proinsulina/genética , Proinsulina/imunologia , Domínios e Motivos de Interação entre Proteínas , Receptores de Antígenos de Linfócitos T/química , Receptores de Antígenos de Linfócitos T/genética , Linfócitos T Reguladores/imunologiaRESUMO
Most studies on the immunotherapeutic potential of T cells have focused on CD8 and CD4 T cells that recognize peptide antigens (Ag) presented by polymorphic major histocompatibility complex (MHC) class I and MHC class II molecules, respectively. However, unconventional T cells, which interact with MHC class Ib and MHC-I like molecules, are also implicated in tumor immunity, although their role therein is unclear. These include unconventional T cells targeting MHC class Ib molecules such as HLA-E and its murine ortholog Qa-1b, natural killer T (NKT) cells, mucosal associated invariant T (MAIT) cells, and γδ T cells. Here, we review the current understanding of the roles of these unconventional T cells in tumor immunity and discuss why further studies into the immunotherapeutic potential of these cells is warranted.
Assuntos
Imunoterapia , Terapia de Alvo Molecular , Neoplasias/imunologia , Neoplasias/terapia , Linfócitos T/imunologia , Linfócitos T/metabolismo , Animais , Biomarcadores , Estudos Clínicos como Assunto , Terapia Combinada , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Antígenos de Histocompatibilidade/imunologia , Antígenos de Histocompatibilidade/metabolismo , Humanos , Imunomodulação/efeitos dos fármacos , Neoplasias/metabolismo , Transdução de Sinais/efeitos dos fármacos , Subpopulações de Linfócitos T/efeitos dos fármacos , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Linfócitos T/efeitos dos fármacos , Resultado do TratamentoRESUMO
To broadly measure the spectrum of cellular self-antigens for natural killer T cells (NKT), we developed a sensitive lipidomics system to analyze lipids trapped between CD1d and NKT T cell receptors (TCRs). We captured diverse antigen complexes formed in cells from natural endogenous lipids, with or without inducing endoplasmic reticulum (ER) stress. After separating protein complexes with no, low, or high CD1d-TCR interaction, we eluted lipids to establish the spectrum of self-lipids that facilitate this interaction. Although this unbiased approach identified fifteen molecules, they clustered into only two related groups: previously known phospholipid antigens and unexpected neutral lipid antigens. Mass spectrometry studies identified the neutral lipids as ceramides, deoxyceramides, and diacylglycerols, which can be considered headless lipids because they lack polar headgroups that usually form the TCR epitope. The crystal structure of the TCR-ceramide-CD1d complex showed how the missing headgroup allowed the TCR to predominantly contact CD1d, supporting a model of CD1d autoreactivity. Ceramide and related headless antigens mediated physiological TCR binding affinity, weak NKT cell responses, and tetramer binding to polyclonal human and mouse NKT cells. Ceramide and sphingomyelin are oppositely regulated components of the "sphingomyelin cycle" that are altered during apoptosis, transformation, and ER stress. Thus, the unique molecular link of ceramide to NKT cell response, along with the recent identification of sphingomyelin blockers of NKT cell activation, provide two mutually reinforcing links for NKT cell response to sterile cellular stress conditions.
Assuntos
Antígenos CD1d , Lipidômica , Células T Matadoras Naturais , Receptores de Antígenos de Linfócitos T , Células T Matadoras Naturais/imunologia , Células T Matadoras Naturais/metabolismo , Antígenos CD1d/imunologia , Antígenos CD1d/metabolismo , Animais , Receptores de Antígenos de Linfócitos T/imunologia , Receptores de Antígenos de Linfócitos T/metabolismo , Camundongos , Lipidômica/métodos , Humanos , Autoantígenos/imunologia , Autoantígenos/metabolismo , Ceramidas/metabolismo , Ceramidas/imunologia , Lipídeos/química , Lipídeos/imunologia , Estresse do Retículo Endoplasmático/imunologiaAssuntos
COVID-19 , Células T Matadoras Naturais , Citocinas , Citometria de Fluxo , Humanos , SARS-CoV-2RESUMO
The T cell repertoire comprises αß and γδ T cell lineages. Although it is established how αß T cell antigen receptors (TCRs) interact with antigen presented by antigen-presenting molecules, this is unknown for γδ TCRs. We describe a population of human Vδ1(+) γδ T cells that exhibit autoreactivity to CD1d and provide a molecular basis for how a γδ TCR binds CD1d-α-galactosylceramide (α-GalCer). The γδ TCR docked orthogonally, over the A' pocket of CD1d, in which the Vδ1-chain, and in particular the germ line-encoded CDR1δ loop, dominated interactions with CD1d. The TCR γ-chain sat peripherally to the interface, with the CDR3γ loop representing the principal determinant for α-GalCer specificity. Accordingly, we provide insight into how a γδ TCR binds specifically to a lipid-loaded antigen-presenting molecule.
Assuntos
Antígenos CD1d/química , Galactosilceramidas/química , Simulação de Acoplamento Molecular , Receptores de Antígenos de Linfócitos T gama-delta/química , Subpopulações de Linfócitos T/imunologia , Sequência de Aminoácidos , Antígenos CD1d/imunologia , Sítios de Ligação , Bases de Dados de Proteínas , Galactosilceramidas/imunologia , Humanos , Dados de Sequência Molecular , Ligação Proteica , Estrutura Terciária de Proteína , Receptores de Antígenos de Linfócitos T gama-delta/imunologia , Subpopulações de Linfócitos T/citologiaRESUMO
Human T cell antigen receptors (TCRs) pair in millions of combinations to create complex and unique T cell repertoires for each person. Through the use of tetramers to analyze TCRs reactive to the antigen-presenting molecule CD1b, we detected T cells with highly stereotyped TCR α-chains present among genetically unrelated patients with tuberculosis. The germline-encoded, mycolyl lipid-reactive (GEM) TCRs had an α-chain bearing the variable (V) region TRAV1-2 rearranged to the joining (J) region TRAJ9 with few nontemplated (N)-region additions. Analysis of TCRs by high-throughput sequencing, binding and crystallography showed linkage of TCRα sequence motifs to high-affinity recognition of antigen. Thus, the CD1-reactive TCR repertoire is composed of at least two compartments: high-affinity GEM TCRs, and more-diverse TCRs with low affinity for CD1b-lipid complexes. We found high interdonor conservation of TCRs that probably resulted from selection by a nonpolymorphic antigen-presenting molecule and an immunodominant antigen.
Assuntos
Antígenos CD1/imunologia , Infecções por Mycobacterium/imunologia , Mycobacterium/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Subpopulações de Linfócitos T/imunologia , Linfócitos T/imunologia , Sequência de Aminoácidos , Sequência de Bases , Células Clonais , Cristalografia por Raios X , Citometria de Fluxo , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Infecções por Mycobacterium/microbiologia , RNA/química , RNA/genética , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNA , Subpopulações de Linfócitos T/citologia , Linfócitos T/citologiaRESUMO
A characteristic of mucosal-associated invariant T (MAIT) cells is the expression of TRAV1-2(+) T cell receptors (TCRs) that are activated by riboflavin metabolite-based antigens (Ag) presented by the MHC-I related molecule, MR1. Whether the MR1-restricted T cell repertoire and associated Ag responsiveness extends beyond these cells remains unclear. Here, we describe MR1 autoreactivity and folate-derivative reactivity in a discrete subset of TRAV1-2(+) MAIT cells. This recognition was attributable to CDR3ß loop-mediated effects within a consensus TRAV1-2(+) TCR-MR1-Ag footprint. Furthermore, we have demonstrated differential folate- and riboflavin-derivative reactivity by a diverse population of "atypical" TRAV1-2(-) MR1-restricted T cells. We have shown that TRAV1-2(-) T cells are phenotypically heterogeneous and largely distinct from TRAV1-2(+) MAIT cells. A TRAV1-2(-) TCR docks more centrally on MR1, thereby adopting a markedly different molecular footprint to the TRAV1-2(+) TCR. Accordingly, diversity within the MR1-restricted T cell repertoire leads to differing MR1-restricted Ag specificity.
Assuntos
Apresentação de Antígeno/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Ativação Linfocitária/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Subpopulações de Linfócitos T/imunologia , Linfócitos T/imunologia , Autoimunidade/imunologia , Cristalografia por Raios X , Citometria de Fluxo , Antígenos de Histocompatibilidade Classe I/química , Humanos , Imunidade nas Mucosas/imunologia , Células Jurkat , Antígenos de Histocompatibilidade Menor , Receptores de Antígenos de Linfócitos T/química , Ressonância de Plasmônio de SuperfícieRESUMO
In recent years, various intervention strategies have reduced malaria morbidity and mortality, but further improvements probably depend upon development of a broadly protective vaccine. To better understand immune requirement for protection, we examined liver-stage immunity after vaccination with irradiated sporozoites, an effective though logistically difficult vaccine. We identified a population of memory CD8+ T cells that expressed the gene signature of tissue-resident memory T (Trm) cells and remained permanently within the liver, where they patrolled the sinusoids. Exploring the requirements for liver Trm cell induction, we showed that by combining dendritic cell-targeted priming with liver inflammation and antigen recognition on hepatocytes, high frequencies of Trm cells could be induced and these cells were essential for protection against malaria sporozoite challenge. Our study highlights the immune potential of liver Trm cells and provides approaches for their selective transfer, expansion, or depletion, which may be harnessed to control liver infections or autoimmunity.