RESUMO
Dynamic tuning of cellular responsiveness as a result of repeated stimuli improves the ability of cells to distinguish physiologically meaningful signals from each other and from noise. In particular, lymphocyte activation thresholds are subject to tuning, which contributes to maintaining tolerance to self-antigens and persisting foreign antigens, averting autoimmunity and immune pathogenesis, but allowing responses to strong, structured perturbations that are typically associated with acute infection. Such tuning is also implicated in conferring flexibility to positive selection in the thymus, in controlling the magnitude of the immune response, and in generating memory cells. Additional functional properties are dynamically and differentially tuned in parallel via subthreshold contact interactions between developing or mature lymphocytes and self-antigen-presenting cells. These interactions facilitate and regulate lymphocyte viability, maintain their functional integrity, and influence their responses to foreign antigens and accessory signals, qualitatively and quantitatively. Bidirectional tuning of T cells and antigen-presenting cells leads to the definition of homeostatic set points, thus maximizing clonal diversity.
Assuntos
Linfócitos/imunologia , Linfócitos/metabolismo , Animais , Sobrevivência Celular/imunologia , Homeostase , Humanos , Memória Imunológica , Infecções/imunologia , Infecções/metabolismo , Ativação Linfocitária/genética , Ativação Linfocitária/imunologia , Linfócitos/citologia , Fenótipo , Subpopulações de Linfócitos T/citologia , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Timócitos/citologia , Timócitos/imunologia , Timócitos/metabolismoRESUMO
Mucosal-associated invariant T cells (MAIT cells) recognize the microbial metabolite 5-(2-oxopropylideneamino)-6-D-ribitylaminouracil (5-OP-RU) presented by the MHC class Ib molecule, MR1. MAIT cells acquire effector functions during thymic development, but the mechanisms involved are unclear. Here we used single-cell RNA-sequencing to characterize the developmental path of 5-OP-RU-specific thymocytes. In addition to the known MAIT1 and MAIT17 effector subsets selected on bone-marrow-derived hematopoietic cells, we identified 5-OP-RU-specific thymocytes that were selected on thymic epithelial cells and differentiated into CD44- naive T cells. MAIT cell positive selection required signaling through the adapter, SAP, that controlled the expression of the transcription factor, ZBTB16. Pseudotemporal ordering of single cells revealed transcriptional trajectories of 5-OP-RU-specific thymocytes selected on either thymic epithelial cells or hematopoietic cells. The resulting model illustrates T cell lineage decisions.
Assuntos
Linhagem da Célula/imunologia , Células T Invariantes Associadas à Mucosa/citologia , Células T Invariantes Associadas à Mucosa/imunologia , Ribitol/análogos & derivados , Timócitos/citologia , Timócitos/imunologia , Uracila/análogos & derivados , Animais , Sequência de Bases , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismo , Receptores de Hialuronatos/metabolismo , Ativação Linfocitária/imunologia , Camundongos , Camundongos Knockout , Antígenos de Histocompatibilidade Menor/metabolismo , Proteína com Dedos de Zinco da Leucemia Promielocítica/biossíntese , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Ribitol/imunologia , Análise de Sequência de RNA , Família de Moléculas de Sinalização da Ativação Linfocitária/metabolismo , Timo/citologia , Timo/imunologia , Uracila/imunologiaRESUMO
The acquisition of a protective vertebrate immune system hinges on the efficient generation of a diverse but self-tolerant repertoire of T cells by the thymus through mechanisms that remain incompletely resolved. Here we identified the endosomal-sorting-complex-required-for-transport (ESCRT) protein CHMP5, known to be required for the formation of multivesicular bodies, as a key sensor of thresholds for signaling via the T cell antigen receptor (TCR) that was essential for T cell development. CHMP5 enabled positive selection by promoting post-selection thymocyte survival in part through stabilization of the pro-survival protein Bcl-2. Accordingly, loss of CHMP5 in thymocyte precursor cells abolished T cell development, a phenotype that was 'rescued' by genetic deletion of the pro-apoptotic protein Bim or transgenic expression of Bcl-2. Mechanistically, positive selection resulted in the stabilization of CHMP5 by inducing its interaction with the deubiquitinase USP8. Our results thus identify CHMP5 as an essential component of the post-translational machinery required for T cell development.
Assuntos
Diferenciação Celular/imunologia , Complexos Endossomais de Distribuição Requeridos para Transporte/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Linfócitos T/imunologia , Timócitos/imunologia , Animais , Proteína 11 Semelhante a Bcl-2/imunologia , Endopeptidases/imunologia , Immunoblotting , Imunoprecipitação , Camundongos , Microscopia Eletrônica de Transmissão , Microscopia de Fluorescência , Processamento de Proteína Pós-Traducional , Proteínas Proto-Oncogênicas c-bcl-2/imunologia , Reação em Cadeia da Polimerase em Tempo Real , Transdução de Sinais/imunologia , Linfócitos T/citologia , Timócitos/citologia , Ubiquitina Tiolesterase/imunologiaRESUMO
TCRαß+CD4-CD8α+CD8ß- intestinal intraepithelial lymphocytes (CD8αα IELs) are an abundant population of thymus-derived T cells that protect the gut barrier surface. We sought to better define the thymic IEL precursor (IELp) through analysis of its maturation, localization and emigration. We defined two precursor populations among TCRß+CD4-CD8- thymocytes by dependence on the kinase TAK1 and rigorous lineage-exclusion criteria. Those IELp populations included a nascent PD-1+ population and a T-bet+ population that accumulated with age. Both gave rise to intestinal CD8αα IELs after adoptive transfer. The PD-1+ IELp population included more strongly self-reactive clones and was largely restricted by classical major histocompatibility complex (MHC) molecules. Those cells localized to the cortex and efficiently emigrated in a manner dependent on the receptor S1PR1. The T-bet+ IELp population localized to the medulla, included cells restricted by non-classical MHC molecules and expressed the receptor NK1.1, the integrin CD103 and the chemokine receptor CXCR3. The two IELp populations further differed in their use of the T cell antigen receptor (TCR) α-chain variable region (Vα) and ß-chain variable region (Vß). These data provide a foundation for understanding the biology of CD8αα IELs.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Mucosa Intestinal/imunologia , Células Precursoras de Linfócitos T/imunologia , Timócitos/imunologia , Imunidade Adaptativa/imunologia , Transferência Adotiva , Animais , Antígenos CD , Antígenos Ly/imunologia , Antígenos CD8/imunologia , Linhagem da Célula , Movimento Celular/imunologia , Citometria de Fluxo , Imunofluorescência , Antígenos de Histocompatibilidade/imunologia , Imunidade nas Mucosas/imunologia , Cadeias alfa de Integrinas , Mucosa Intestinal/citologia , Linfócitos , Camundongos , Subfamília B de Receptores Semelhantes a Lectina de Células NK/imunologia , Fenótipo , Receptor de Morte Celular Programada 1/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Receptores CXCR3 , Receptores de Lisoesfingolipídeo/imunologia , Receptores de Esfingosina-1-Fosfato , Proteínas com Domínio T/imunologia , Timócitos/citologia , Timo/citologiaRESUMO
THEMIS, a T cell-specific protein with high expression in CD4+CD8+ thymocytes, has a crucial role in positive selection and T cell development. THEMIS lacks defined catalytic domains but contains two tandem repeats of a distinctive module of unknown function (CABIT). Here we found that THEMIS directly regulated the catalytic activity of the tyrosine phosphatase SHP-1. This action was mediated by the CABIT modules, which bound to the phosphatase domain of SHP-1 and promoted or stabilized oxidation of SHP-1's catalytic cysteine residue, which inhibited the tyrosine-phosphatase activity of SHP-1. Deletion of SHP-1 alleviated the developmental block in Themis-/- thymocytes. Thus, THEMIS facilitates thymocyte positive selection by enhancing the T cell antigen receptor signaling response to low-affinity ligands.
Assuntos
Seleção Clonal Mediada por Antígeno/imunologia , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 6/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Transdução de Sinais , Linfócitos T/imunologia , Linfócitos T/metabolismo , Animais , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Linhagem Celular , Deleção de Genes , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Camundongos , Camundongos Knockout , Oxirredução , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteína Tirosina Fosfatase não Receptora Tipo 6/antagonistas & inibidores , Proteína Tirosina Fosfatase não Receptora Tipo 6/química , Proteína Tirosina Fosfatase não Receptora Tipo 6/genética , Espécies Reativas de Oxigênio/metabolismo , Linfócitos T/citologia , Timócitos/citologia , Timócitos/imunologia , Timócitos/metabolismoRESUMO
The transcription factor RORγt regulates differentiation of the TH17 subset of helper T cells, thymic T cell development and lymph-node genesis. Although elimination of RORγt prevents TH17 cell-mediated experimental autoimmune encephalomyelitis (EAE), it also disrupts thymocyte development, which could lead to lethal thymic lymphoma. Here we identified a two-amino-acid substitution in RORγt (RORγtM) that 'preferentially' disrupted TH17 differentiation but not thymocyte development. Mice expressing RORγtM were resistant to EAE associated with defective TH17 differentiation but maintained normal thymocyte development and normal lymph-node genesis, except for Peyer's patches. RORγtM showed less ubiquitination at Lys69 that was selectively required for TH17 differentiation but not T cell development. This study will inform the development of treatments that selectively target TH17 cell-mediated autoimmunity but do not affect thymocyte development or induce lymphoma.
Assuntos
Substituição de Aminoácidos , Diferenciação Celular/genética , Mutação , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/genética , Células Th17/citologia , Células Th17/metabolismo , Timócitos/citologia , Timócitos/metabolismo , Animais , Biomarcadores , Diferenciação Celular/imunologia , Análise por Conglomerados , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/imunologia , Encefalomielite Autoimune Experimental/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Imunofenotipagem , Linfonodos/imunologia , Linfonodos/metabolismo , Camundongos , Camundongos Knockout , Nódulos Linfáticos Agregados/imunologia , Nódulos Linfáticos Agregados/metabolismo , Subpopulações de Linfócitos T/citologia , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Células Th17/imunologia , Timócitos/imunologia , UbiquitinaçãoRESUMO
During postnatal life, thymopoiesis depends on the continuous colonization of the thymus by bone-marrow-derived hematopoietic progenitors that migrate through the bloodstream. The current understanding of the nature of thymic immigrants is largely based on data from pre-clinical models. Here, we employed single-cell RNA sequencing (scRNA-seq) to examine the immature postnatal thymocyte population in humans. Integration of bone marrow and peripheral blood precursor datasets identified two putative thymus seeding progenitors that varied in expression of CD7; CD10; and the homing receptors CCR7, CCR9, and ITGB7. Whereas both precursors supported T cell development, only one contributed to intrathymic dendritic cell (DC) differentiation, predominantly of plasmacytoid dendritic cells. Trajectory inference delineated the transcriptional dynamics underlying early human T lineage development, enabling prediction of transcription factor (TF) modules that drive stage-specific steps of human T cell development. This comprehensive dataset defines the expression signature of immature human thymocytes and provides a resource for the further study of human thymopoiesis.
Assuntos
Diferenciação Celular , Regulação da Expressão Gênica no Desenvolvimento , Células Progenitoras Linfoides/citologia , Células Progenitoras Linfoides/metabolismo , RNA Citoplasmático Pequeno/genética , Timócitos/citologia , Timócitos/metabolismo , Biomarcadores , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Linhagem da Célula/genética , Perfilação da Expressão Gênica , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Imunofenotipagem , Análise de Célula Única , Timócitos/imunologia , TranscriptomaRESUMO
The challenges in recapitulating in vivo human T cell development in laboratory models have posed a barrier to understanding human thymopoiesis. Here, we used single-cell RNA sequencing (sRNA-seq) to interrogate the rare CD34+ progenitor and the more differentiated CD34- fractions in the human postnatal thymus. CD34+ thymic progenitors were comprised of a spectrum of specification and commitment states characterized by multilineage priming followed by gradual T cell commitment. The earliest progenitors in the differentiation trajectory were CD7- and expressed a stem-cell-like transcriptional profile, but had also initiated T cell priming. Clustering analysis identified a CD34+ subpopulation primed for the plasmacytoid dendritic lineage, suggesting an intrathymic dendritic specification pathway. CD2 expression defined T cell commitment stages where loss of B cell potential preceded that of myeloid potential. These datasets delineate gene expression profiles spanning key differentiation events in human thymopoiesis and provide a resource for the further study of human T cell development.
Assuntos
Diferenciação Celular/genética , Linhagem da Célula/genética , Linfopoese/genética , Linfócitos T/metabolismo , Timócitos/metabolismo , Animais , Biomarcadores , Biologia Computacional , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , Imunofenotipagem , Camundongos , Análise de Célula Única , Linfócitos T/citologia , Timócitos/citologia , TranscriptomaRESUMO
In the thymus, high-affinity, self-reactive thymocytes are eliminated from the pool of developing T cells, generating central tolerance. Here, we investigate how developing T cells measure self-antigen affinity. We show that very few CD4 or CD8 coreceptor molecules are coupled with the signal-initiating kinase, Lck. To initiate signaling, an antigen-engaged T cell receptor (TCR) scans multiple coreceptor molecules to find one that is coupled to Lck; this is the first and rate-limiting step in a kinetic proofreading chain of events that eventually leads to TCR triggering and negative selection. MHCII-restricted TCRs require a shorter antigen dwell time (0.2 s) to initiate negative selection compared to MHCI-restricted TCRs (0.9 s) because more CD4 coreceptors are Lck-loaded compared to CD8. We generated a model (Lck come&stay/signal duration) that accurately predicts the observed differences in antigen dwell-time thresholds used by MHCI- and MHCII-restricted thymocytes to initiate negative selection and generate self-tolerance.
Assuntos
Autoantígenos/imunologia , Tolerância Imunológica , Receptores de Antígenos de Linfócitos T/imunologia , Animais , Antígenos de Histocompatibilidade Classe I/imunologia , Antígenos de Histocompatibilidade Classe II/imunologia , Cinética , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/metabolismo , Cadeias de Markov , Camundongos Endogâmicos C57BL , Receptores de Antígenos de Linfócitos T/metabolismo , Timócitos/citologia , Timócitos/imunologiaRESUMO
Programming T cells to distinguish self from non-self is a vital, multi-step process that occurs in the thymus1-4. Signalling through the pre-T cell receptor (preTCR), a CD3-associated heterodimer comprising an invariant pTα chain and a clone-specific ß chain, is a critical early checkpoint in thymocyte development within the αß T cell lineage5,6. PreTCRs arrayed on CD4-CD8- double-negative thymocytes ligate peptides bound to major histocompatibility complex molecules (pMHC) on thymic stroma, similar to αß T cell receptors that appear on CD4+CD8+ double-positive thymocytes, but via a different molecular docking strategy7-10. Here we show the consequences of these distinct interactions for thymocyte progression using synchronized fetal thymic progenitor cultures that differ in the presence or absence of pMHC on support stroma, and single-cell transcriptomes at key thymocyte developmental transitions. Although major histocompatibility complex (MHC)-negative stroma fosters αß T cell differentiation, the absence of preTCR-pMHC interactions leads to deviant thymocyte transcriptional programming associated with dedifferentiation. Highly proliferative double-negative and double-positive thymocyte subsets emerge, with antecedent characteristics of T cell lymphoblastic and myeloid malignancies. Compensatory upregulation of diverse MHC class Ib proteins in B2m/H2-Ab1 MHC-knockout mice partially safeguards in vivo thymocyte progression, although disseminated double-positive thymic tumours may develop with ageing. Thus, as well as promoting ß chain repertoire broadening for subsequent αß T cell receptor utilization, preTCR-pMHC interactions limit cellular plasticity to facilitate normal thymocyte differentiation and proliferation that, if absent, introduce developmental vulnerabilities.
Assuntos
Desdiferenciação Celular , Antígenos de Histocompatibilidade Classe I , Receptores de Antígenos de Linfócitos T , Timócitos , Animais , Camundongos , Camundongos Knockout , Simulação de Acoplamento Molecular , Peptídeos/imunologia , Peptídeos/metabolismo , Timócitos/citologia , Timócitos/imunologia , Timo/citologia , Timo/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Receptores de Antígenos de Linfócitos T/metabolismo , Antígenos de Histocompatibilidade Classe I/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismoRESUMO
NF-κB (nuclear factor κB) signaling is considered critical for single positive (SP) thymocyte development because loss of upstream activators of NF-κB, such as the IKK complex, arrests their development. We found that the compound ablation of RelA, cRel, and p50, required for canonical NF-κB transcription, had no impact upon thymocyte development. While IKK-deficient thymocytes were acutely sensitive to tumor necrosis factor (TNF)-induced cell death, Rel-deficient cells remained resistant, calling into question the importance of NF-κB as the IKK target required for thymocyte survival. Instead, we found that IKK controlled thymocyte survival by repressing cell-death-inducing activity of the serine/threonine kinase RIPK1. We observed that RIPK1 expression was induced during development of SP thymocytes and that IKK was required to prevent RIPK1-kinase-dependent death of SPs in vivo. Finally, we showed that IKK was required to protect Rel-deficient thymocytes from RIPK1-dependent cell death, underscoring the NF-κB-independent function of IKK during thymic development.
Assuntos
Quinase I-kappa B/metabolismo , NF-kappa B/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Timócitos/metabolismo , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Células Cultivadas , Regulação da Expressão Gênica/efeitos dos fármacos , Quinase I-kappa B/genética , Camundongos Endogâmicos C57BL , Camundongos Knockout , NF-kappa B/genética , Proteína Serina-Treonina Quinases de Interação com Receptores/genética , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Timócitos/citologia , Timócitos/efeitos dos fármacos , Fator de Transcrição RelA/genética , Fator de Transcrição RelA/metabolismo , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
Signaling via the pre-T cell antigen receptor (pre-TCR) and the receptor Notch1 induces transient self-renewal (ß-selection) of TCRß(+) CD4(-)CD8(-) double-negative stage 3 (DN3) and DN4 progenitor cells that differentiate into CD4(+)CD8(+) double-positive (DP) thymocytes, which then rearrange the locus encoding the TCR α-chain (Tcra). Interleukin 7 (IL-7) promotes the survival of TCRß(-) DN thymocytes by inducing expression of the pro-survival molecule Bcl-2, but the functions of IL-7 during ß-selection have remained unclear. Here we found that IL-7 signaled TCRß(+) DN3 and DN4 thymocytes to upregulate genes encoding molecules involved in cell growth and repressed the gene encoding the transcriptional repressor Bcl-6. Accordingly, IL-7-deficient DN4 cells lacked trophic receptors and did not proliferate but rearranged Tcra prematurely and differentiated rapidly. Deletion of Bcl6 partially restored the self-renewal of DN4 cells in the absence of IL-7, but overexpression of BCL2 did not. Thus, IL-7 critically acts cooperatively with signaling via the pre-TCR and Notch1 to coordinate proliferation, differentiation and Tcra recombination during ß-selection.
Assuntos
Interleucina-7/genética , Receptor Notch1/genética , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Timócitos/metabolismo , Animais , Antígenos CD4/genética , Antígenos CD4/imunologia , Antígenos CD8/genética , Antígenos CD8/imunologia , Diferenciação Celular , Proliferação de Células , Sobrevivência Celular , Regulação da Expressão Gênica , Interleucina-7/deficiência , Interleucina-7/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/imunologia , Proteínas Proto-Oncogênicas c-bcl-6/deficiência , Proteínas Proto-Oncogênicas c-bcl-6/genética , Proteínas Proto-Oncogênicas c-bcl-6/imunologia , Receptor Notch1/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Recombinação Genética , Transdução de Sinais , Timócitos/citologia , Timócitos/imunologia , Timo/citologia , Timo/imunologia , Timo/metabolismoRESUMO
The NF-κB signal transduction pathway is best known as a major regulator of innate and adaptive immune responses, yet there is a growing appreciation of its importance in immune cell development, particularly of T lineage cells. In this Review, we discuss how the temporal regulation of NF-κB controls the stepwise differentiation and antigen-dependent selection of conventional and specialized subsets of T cells in response to T cell receptor and costimulatory, cytokine and growth factor signals.
Assuntos
NF-kappa B/imunologia , Transdução de Sinais/imunologia , Linfócitos T/imunologia , Timócitos/imunologia , Linhagem da Célula/imunologia , Humanos , Modelos Imunológicos , NF-kappa B/metabolismo , Receptores de Antígenos de Linfócitos T/imunologia , Receptores de Antígenos de Linfócitos T/metabolismo , Linfócitos T/citologia , Linfócitos T/metabolismo , Timócitos/citologia , Timócitos/metabolismoRESUMO
The generation of T cells depends on the migration of hematopoietic progenitor cells to the thymus throughout life. The identity of the thymus-settling progenitor cells has been a matter of considerable debate. Here we found that thymopoiesis was initiated by a first wave of T cell lineage-restricted progenitor cells with limited capacity for population expansion but accelerated differentiation into mature T cells. They gave rise to αß and γδ T cells that constituted Vγ3(+) dendritic epithelial T cells. Thymopoiesis was subsequently maintained by less-differentiated progenitor cells that retained the potential to develop into B cells and myeloid cells. In that second wave, which started before birth, progenitor cells had high proliferative capacity but delayed differentiation capacity and no longer gave rise to embryonic γδ T cells. Our work reconciles conflicting hypotheses on the nature of thymus-settling progenitor cells.
Assuntos
Diferenciação Celular/genética , Células-Tronco Hematopoéticas/metabolismo , Linfócitos T/metabolismo , Timo/metabolismo , Animais , Animais Recém-Nascidos , Linhagem Celular , Linhagem da Célula/genética , Células Cultivadas , Citometria de Fluxo , Regulação da Expressão Gênica no Desenvolvimento , Células-Tronco Hematopoéticas/citologia , Subunidade alfa de Receptor de Interleucina-7/genética , Subunidade alfa de Receptor de Interleucina-7/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Análise de Sequência com Séries de Oligonucleotídeos , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Receptores de Antígenos de Linfócitos T alfa-beta/metabolismo , Receptores de Antígenos de Linfócitos T gama-delta/genética , Receptores de Antígenos de Linfócitos T gama-delta/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Linfócitos T/citologia , Timócitos/citologia , Timócitos/metabolismo , Timo/citologia , Timo/embriologia , Fatores de Tempo , Transcriptoma , Tirosina Quinase 3 Semelhante a fms/genética , Tirosina Quinase 3 Semelhante a fms/metabolismoRESUMO
Innate and adaptive lymphoid development is orchestrated by the activities of E proteins and their antagonist Id proteins, but how these factors regulate early T cell progenitor (ETP) and innate lymphoid cell (ILC) development remains unclear. Using multiple genetic strategies, we demonstrated that E proteins E2A and HEB acted in synergy in the thymus to establish T cell identity and to suppress the aberrant development of ILCs, including ILC2s and lymphoid-tissue-inducer-like cells. E2A and HEB orchestrated T cell fate and suppressed the ILC transcription signature by activating the expression of genes associated with Notch receptors, T cell receptor (TCR) assembly, and TCR-mediated signaling. E2A and HEB acted in ETPs to establish and maintain a T-cell-lineage-specific enhancer repertoire, including regulatory elements associated with the Notch1, Rag1, and Rag2 loci. On the basis of these and previous observations, we propose that the E-Id protein axis specifies innate and adaptive lymphoid cell fate.
Assuntos
Imunidade Adaptativa , Imunidade Inata , Imunomodulação , Subpopulações de Linfócitos/imunologia , Timócitos/imunologia , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Diferenciação Celular/imunologia , Análise por Conglomerados , Expressão Gênica , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Redes Reguladoras de Genes , Imunofenotipagem , Proteína 2 Inibidora de Diferenciação/genética , Proteína 2 Inibidora de Diferenciação/metabolismo , Ativação Linfocitária/genética , Ativação Linfocitária/imunologia , Subpopulações de Linfócitos/citologia , Subpopulações de Linfócitos/metabolismo , Células Progenitoras Linfoides/metabolismo , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Fenótipo , Especificidade do Receptor de Antígeno de Linfócitos T/imunologia , Timócitos/citologia , Timócitos/metabolismo , TranscriptomaRESUMO
Interleukin 7 (IL-7) has a critical role in the development of early CD4(-)CD8(-) double-negative (DN) thymocytes. Although the transcription factor STAT5 is an important component of IL-7 signaling, differences in the phenotypes of mice deficient in STAT5, IL-7, IL-7 receptor alpha (IL-7rα) or the kinase Jak3 suggest the existence of STAT5-independent IL-7 signaling. Here we found that IL-7-Jak3 signals activated the transcription factor NFATc1 in DN thymocytes by phosphorylating Tyr371 in the regulatory region of NFATc1. This NFAT-activation pathway was critical for the survival and development of DN thymocytes, as deficiency in NFATc1 blocked thymocyte development at the DN1 stage, leading to T cell lymphopenia. In addition, our results demonstrated a cooperative function for NFATc1 and STAT5 in guiding thymocyte development in response to IL-7 signals.
Assuntos
Interleucina-7/genética , Fatores de Transcrição NFATC/genética , Fator de Transcrição STAT5/genética , Transdução de Sinais/imunologia , Timócitos/citologia , Animais , Antígenos CD4/genética , Antígenos CD4/imunologia , Antígenos CD8/genética , Antígenos CD8/imunologia , Diferenciação Celular , Regulação da Expressão Gênica , Interleucina-7/imunologia , Janus Quinase 3/genética , Janus Quinase 3/imunologia , Linfopenia/imunologia , Linfopenia/patologia , Camundongos , Camundongos Transgênicos , Fatores de Transcrição NFATC/deficiência , Fosforilação , Regiões Promotoras Genéticas , Receptores de Interleucina-7/genética , Receptores de Interleucina-7/imunologia , Fator de Transcrição STAT5/imunologia , Timócitos/imunologia , Transcrição GênicaRESUMO
The differentiation of αßT cells from thymic precursors is a complex process essential for adaptive immunity. Here we exploited the breadth of expression data sets from the Immunological Genome Project to analyze how the differentiation of thymic precursors gives rise to mature T cell transcriptomes. We found that early T cell commitment was driven by unexpectedly gradual changes. In contrast, transit through the CD4(+)CD8(+) stage involved a global shutdown of housekeeping genes that is rare among cells of the immune system and correlated tightly with expression of the transcription factor c-Myc. Selection driven by major histocompatibility complex (MHC) molecules promoted a large-scale transcriptional reactivation. We identified distinct signatures that marked cells destined for positive selection versus apoptotic deletion. Differences in the expression of unexpectedly few genes accompanied commitment to the CD4(+) or CD8(+) lineage, a similarity that carried through to peripheral T cells and their activation, demonstrated by mass cytometry phosphoproteomics. The transcripts newly identified as encoding candidate mediators of key transitions help define the 'known unknowns' of thymocyte differentiation.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Diferenciação Celular/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Animais , Antígenos CD/imunologia , Antígenos CD/metabolismo , Antígenos de Diferenciação de Linfócitos T/imunologia , Antígenos de Diferenciação de Linfócitos T/metabolismo , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD8-Positivos/metabolismo , Diferenciação Celular/genética , Linhagem da Célula/genética , Linhagem da Célula/imunologia , Proliferação de Células , Células Cultivadas , Análise por Conglomerados , Citometria de Fluxo , Antígenos de Histocompatibilidade/genética , Antígenos de Histocompatibilidade/imunologia , Antígenos de Histocompatibilidade/metabolismo , Lectinas Tipo C/imunologia , Lectinas Tipo C/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Análise de Sequência com Séries de Oligonucleotídeos , Fosforilação/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Receptores de Antígenos de Linfócitos T alfa-beta/metabolismo , Timócitos/citologia , Timócitos/imunologia , Timócitos/metabolismo , Transcriptoma/genética , Transcriptoma/imunologiaRESUMO
Cytotoxic T cells are essential mediators of protective immunity to viral infection and malignant tumours and are a key target of immunotherapy approaches. However, prolonged exposure to cognate antigens often attenuates the effector capacity of T cells and limits their therapeutic potential1-4. This process, known as T cell exhaustion or dysfunction1, is manifested by epigenetically enforced changes in gene regulation that reduce the expression of cytokines and effector molecules and upregulate the expression of inhibitory receptors such as programmed cell-death 1 (PD-1)5-8. The underlying molecular mechanisms that induce and stabilize the phenotypic and functional features of exhausted T cells remain poorly understood9-12. Here we report that the development and maintenance of populations of exhausted T cells in mice requires the thymocyte selection-associated high mobility group box (TOX) protein13-15. TOX is induced by high antigen stimulation of the T cell receptor and correlates with the presence of an exhausted phenotype during chronic infections with lymphocytic choriomeningitis virus in mice and hepatitis C virus in humans. Removal of its DNA-binding domain reduces the expression of PD-1 at the mRNA and protein level, augments the production of cytokines and results in a more polyfunctional T cell phenotype. T cells with this deletion initially mediate increased effector function and cause more severe immunopathology, but ultimately undergo a massive decline in their quantity, notably among the subset of TCF-1+ self-renewing T cells. Altogether, we show that TOX is a critical factor for the normal progression of T cell dysfunction and the maintenance of exhausted T cells during chronic infection, and provide a link between the suppression of effector function intrinsic to CD8 T cells and protection against immunopathology.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/patologia , Hepatite C Crônica/imunologia , Hepatite C Crônica/virologia , Proteínas de Grupo de Alta Mobilidade/metabolismo , Proteínas de Homeodomínio/metabolismo , Coriomeningite Linfocítica/imunologia , Coriomeningite Linfocítica/virologia , Animais , Proliferação de Células , Doença Crônica , Citocinas/imunologia , Citocinas/metabolismo , Epigênese Genética , Feminino , Regulação da Expressão Gênica/imunologia , Hepacivirus/imunologia , Fator 1-alfa Nuclear de Hepatócito/metabolismo , Humanos , Memória Imunológica , Vírus da Coriomeningite Linfocítica/imunologia , Masculino , Camundongos , Fenótipo , Timócitos/citologia , Timócitos/imunologia , Transcrição GênicaRESUMO
Clonal deletion of autoreactive thymocytes is important for self-tolerance, but the intrathymic signals that induce clonal deletion have not been clearly identified. We now report that clonal deletion during negative selection required CD28-mediated costimulation of autoreactive thymocytes at the CD4(+)CD8(lo) intermediate stage of differentiation. Autoreactive thymocytes were prevented from undergoing clonal deletion by either a lack of CD28 costimulation or transgenic overexpression of the antiapoptotic factors Bcl-2 or Mcl-1, with surviving thymocytes differentiating into anergic CD4(-)CD8(-) double-negative thymocytes positive for the T cell antigen receptor αß subtype (TCRαß) that 'preferentially' migrated to the intestine, where they re-expressed CD8α and were sequestered as CD8αα(+) intraepithelial lymphocytes (IELs). Our study identifies costimulation by CD28 as the intrathymic signal required for clonal deletion and identifies CD8αα(+) IELs as the developmental fate of autoreactive thymocytes that survive negative selection.
Assuntos
Diferenciação Celular/imunologia , Deleção Clonal/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Timócitos/imunologia , Timo/imunologia , Animais , Antígenos CD28/imunologia , Antígenos CD4/imunologia , Antígenos CD8/imunologia , Citometria de Fluxo , Tolerância Imunológica/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Transdução de Sinais/imunologia , Timócitos/citologia , Timo/citologiaRESUMO
The development and maturation of semi-invariant natural killer T cells (iNKT cells) rely on the recognition of self antigens presented by CD1d restriction molecules in thymus. The nature of the stimulatory thymic self lipids remains elusive. We isolated lipids from thymocytes and found that ether-bonded mono-alkyl glycerophosphates and the precursors and degradation products of plasmalogens stimulated iNKT cells. Synthetic analogs showed high potency in activating thymic and peripheral iNKT cells. Mice deficient in the peroxisomal enzyme glyceronephosphate O-acyltransferase (GNPAT), essential for the synthesis of ether lipids, had significant alteration of the thymic maturation of iNKT cells and fewer iNKT cells in both thymus and peripheral organs, which confirmed the role of ether-bonded lipids as iNKT cell antigens. Thus, peroxisome-derived lipids are nonredundant self antigens required for the generation of a full iNKT cell repertoire.