RESUMO
Follicular helper T cells (T(FH) cells) provide critical help to B cells during humoral immune responses. Here we report that mice with T cell-specific deletion of the miR-17â¼92 family of microRNAs (miRNAs) had substantially compromised T(FH) differentiation, germinal-center formation and antibody responses and failed to control chronic viral infection. Conversely, mice with T cell-specific expression of a transgene encoding miR-17â¼92 spontaneously accumulated T(FH) cells and developed a fatal immunopathology. Mechanistically, the miR-17â¼92 family controlled the migration of CD4(+) T cells into B cell follicles by regulating signaling intensity from the inducible costimulator ICOS and kinase PI(3)K by suppressing expression of the phosphatase PHLPP2. Our findings demonstrate an essential role for the miR-17â¼92 family in T(FH) differentiation and establish PHLPP2 as an important mediator of their function in this process.
Assuntos
Linfócitos B/imunologia , Diferenciação Celular/imunologia , Centro Germinativo/imunologia , MicroRNAs/imunologia , Proteínas Nucleares/imunologia , Fosfoproteínas Fosfatases/imunologia , Linfócitos T Auxiliares-Indutores/imunologia , Animais , Citometria de Fluxo , Centro Germinativo/citologia , Imunidade Humoral/imunologia , Imuno-Histoquímica , Proteína Coestimuladora de Linfócitos T Induzíveis/imunologia , Coriomeningite Linfocítica/imunologia , Coriomeningite Linfocítica/virologia , Vírus da Coriomeningite Linfocítica/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Fosfatidilinositol 3-Quinases/imunologia , Transdução de Sinais/imunologia , Organismos Livres de Patógenos Específicos , Linfócitos T Auxiliares-Indutores/citologia , Linfócitos T Auxiliares-Indutores/enzimologiaRESUMO
Histone deacetylase 7 (HDAC7) is a T-cell receptor (TCR) signal-dependent regulator of differentiation that is highly expressed in CD4/CD8 double-positive (DP) thymocytes. Here, we examine the effect of blocking TCR-dependent nuclear export of HDAC7 during thymic selection, through expression of a signal-resistant mutant of HDAC7 (HDAC7-ΔP) in thymocytes. We find that HDAC7-ΔP transgenic thymocytes exhibit a profound block in negative thymic selection, but can still undergo positive selection, resulting in the escape of autoreactive T cells into the periphery. Gene expression profiling reveals a comprehensive suppression of the negative selection-associated gene expression programme in DP thymocytes, associated with a defect in the activation of MAP kinase pathways by TCR signals. The consequence of this block in vivo is a lethal autoimmune syndrome involving the exocrine pancreas and other abdominal organs. These experiments establish a novel molecular model of autoimmunity and cast new light on the relationship between thymic selection and immune self-tolerance.
Assuntos
Transporte Ativo do Núcleo Celular , Antígenos CD4/biossíntese , Antígenos CD8/biossíntese , Histona Desacetilases/metabolismo , Timócitos/citologia , Timo/imunologia , Animais , Autoimunidade , Proliferação de Células , Feminino , Citometria de Fluxo/métodos , Regulação da Expressão Gênica , Sistema Imunitário , Sistema de Sinalização das MAP Quinases , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação , Análise de Sequência com Séries de Oligonucleotídeos , Transdução de Sinais , Timo/metabolismoRESUMO
The Foxp3 transcription factor is the master regulator of regulatory T cell (Treg) differentiation and function. Its activity is regulated by reversible acetylation. Using mass spectrometry of immunoprecipitated proteins, we identify three novel acetylation sites in murine Foxp3 (K31, K262, and K267) and the corresponding sites in human FOXP3 proteins. Newly raised modification-specific Abs against acetylated K31 and K267 confirm acetylation of these residues in murine Tregs. Mutant Foxp3 proteins carrying arginine substitutions at the three acetylation sites (3KR) accumulate in T cells to higher levels than wild-type Foxp3 and exert better suppressive activity in coculture experiments. Acetylation and stability of wild-type, but not mutant, Foxp3 is enhanced when cells are treated with Ex-527, an inhibitor of the NAD(+)-dependent deacetylase SIRT1. Treatment with Ex-527 promotes Foxp3 expression during induced Treg differentiation, enhances Foxp3 levels in natural Tregs, and prevents loss of Foxp3 expression in adoptively transferred Tregs in mice. Our data identify SIRT1 as a negative regulator of Treg function via deacetylation of three novel target sites in Foxp3. SIRT1 inhibitors strengthen the suppressive activity of Tregs and may be useful in enhancing Treg-based therapeutic approaches to autoimmune diseases or graft rejections.
Assuntos
Fatores de Transcrição Forkhead/química , Fatores de Transcrição Forkhead/genética , Tolerância Imunológica/imunologia , Linfócitos T Reguladores/imunologia , Acetilação , Transferência Adotiva , Sequência de Aminoácidos , Animais , Western Blotting , Diferenciação Celular/imunologia , Fatores de Transcrição Forkhead/imunologia , Humanos , Imunoprecipitação , Células Jurkat , Espectrometria de Massas , Camundongos , Dados de Sequência Molecular , RNA Mensageiro/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , TransfecçãoRESUMO
OBJECTIVE: Vascular endothelial growth factor (VEGF) promotes leukocyte adhesion to endothelial cells (ECs). Angiopoietin-1 (Ang-1) inhibits this response. Nuclear receptor-77 (Nur77) is a proangiogenic nuclear receptor. In the present study, we assessed the influence of Ang-1 and VEGF on Nur77 expression in ECs, and evaluated its role in Ang-1/VEGF-mediated leukocyte adhesion. METHODS AND RESULTS: Expression of Nur77 was evaluated with real-time polymerase chain reaction and immunoblotting. Adhesion of leukocytes to ECs was monitored with inverted microscopy. Nur77 expression or activity was inhibited using adenoviruses expressing dominant-negative form of Nur77, retroviruses expressing Nur77 in the antisense direction, and small interfering RNA oligos. Both Ang-1 and VEGF induce Nur77 expression, by >5- and 30-fold, respectively. When combined, Ang-1 potentiates VEGF-induced Nur77 expression. Ang-1 induces Nur77 through the phosphoinositide 3-kinase and extracellular signal-regulated protein kinase 1/2 pathways. VEGF induces Nur77 expression through the protein kinase D/histone deacetylase 7/myocyte enhancer factor 2 and extracellular signal-regulated protein kinase 1/2 pathways. VEGF induces nuclear factor-kappaB transcription factor, vascular cell adhesion molecule-1, and E-selectin expressions, and promotes leukocyte adhesion to ECs. Ang-1 inhibits these responses. This inhibitory effect of Ang-1 disappears when Nur77 expression is disrupted, restoring the inductive effects of VEGF on adhesion molecule expression, and increased leukocyte adhesion to ECs. CONCLUSIONS: Nur77 promotes anti-inflammatory effects of Ang-1, and functions as a negative feedback inhibitor of VEGF-induced EC activation.
Assuntos
Angiopoietina-1/farmacologia , Células Endoteliais/efeitos dos fármacos , Leucócitos/efeitos dos fármacos , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/fisiologia , Fator A de Crescimento do Endotélio Vascular/farmacologia , Adesão Celular/efeitos dos fármacos , Células Cultivadas , Células Endoteliais/fisiologia , Histona Desacetilases/metabolismo , Humanos , Quinase I-kappa B/genética , Leucócitos/fisiologia , NF-kappa B/metabolismo , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/genética , Fosfatidilinositol 3-Quinases/fisiologia , Fosforilação , Proteínas Proto-Oncogênicas c-akt/fisiologia , Canais de Cátion TRPP/metabolismo , Células U937 , Molécula 1 de Adesão de Célula Vascular/genéticaRESUMO
CD4/CD8 double-positive thymocytes express the transcriptional repressor histone deacetylase (HDAC)7, a class IIa HDAC that is exported from the cell nucleus after TCR engagement. Through signal-dependent nuclear export, class IIa HDACs such as HDAC7 mediate signal-dependent changes in gene expression that are important to developmental fate decisions in multiple tissues. We report that HDAC7 is exported from the cell nucleus during positive selection in mouse thymocytes and that it regulates genes mediating the coupling between TCR engagement and downstream events that determine cell survival. Thymocytes lacking HDAC7 are inefficiently positively selected due to a severely shortened lifespan and exhibit a truncated repertoire of TCR Jα segments. The expression of multiple important mediators and modulators of the response to TCR engagement is altered in HDAC7-deficient thymocytes, resulting in increased tonic MAPK activity that contributes to the observed loss of viability. Remarkably, the activity of protein kinase D, the kinase that mediates nuclear export of HDAC7 in response to TCR signaling, is also increased in HDAC7-deficient thymocytes, suggesting that HDAC7 nuclear export governs a self-sustaining autoexcitatory loop. These experiments add to the understanding of the life/death decision in thymic T cell development, define a novel function for class IIa HDACs, and point to a novel feed-forward mechanism whereby these molecules regulate their own state and mediate stable developmental transitions.
Assuntos
Antígenos CD4/metabolismo , Antígenos CD8/metabolismo , Histona Desacetilases/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Transdução de Sinais , Timo/metabolismo , Animais , Apoptose , Western Blotting , Núcleo Celular/metabolismo , Sobrevivência Celular , Feminino , Perfilação da Expressão Gênica , Histona Desacetilases/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia de Fluorescência , Análise de Sequência com Séries de Oligonucleotídeos , Proteína Quinase C/metabolismo , Transporte Proteico , Receptores de Antígenos de Linfócitos T/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Linfócitos T/metabolismo , Timo/citologiaRESUMO
The effector function of tumor-infiltrated CD4+ T cells is readily suppressed by many types of immune regulators in the tumor microenvironment, which is one of the major mechanisms of immune tolerance against cancer. Cathelicidin-related antimicrobial peptide (CRAMP), the mouse analog of LL-37 peptide in humans, is a cationic antimicrobial peptide belonging to the cathelicidin family; however, its secretion by cancer cells and role in the tumor microenvironment (TME) remain unclear. In this study, we explored the possibility of an interaction between effector CD4+ T cells and CRAMP using in vitro-generated mouse Th17 cells. We found that CRAMP stimulates Th17 cells to express the ectonucleotidase CD73, while simultaneously inducing cell death. This finding suggested that CD73-expressing Th17 cells may function as immune suppressor cells instead of effector cells. In addition, treatment of pharmacological inhibitors of the transforming growth factor-beta (TGF-ß) signaling pathway showed that induction of CD73 expression is mediated by the p38 signaling pathway. Overall, our findings suggest that tumor-derived LL-37 likely functions as an immune suppressor that induces immune tolerance against tumors through shaping effector Th17 cells into suppressor Th17 cells, suggesting a new intervention target to improve cancer immunotherapy.
Assuntos
Antígenos de Neoplasias/metabolismo , Peptídeos Catiônicos Antimicrobianos/metabolismo , Tetraspaninas/metabolismo , Células Th17/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo , Animais , Feminino , Humanos , CamundongosRESUMO
We report that Histone Deacetylase 7 (HDAC7) controls the thymic effector programming of Natural Killer T (NKT) cells, and that interference with this function contributes to tissue-specific autoimmunity. Gain of HDAC7 function in thymocytes blocks both negative selection and NKT development, and diverts Vα14/Jα18 TCR transgenic thymocytes into a Tconv-like lineage. Conversely, HDAC7 deletion promotes thymocyte apoptosis and causes expansion of innate-effector cells. Investigating the mechanisms involved, we found that HDAC7 binds PLZF and modulates PLZF-dependent transcription. Moreover, HDAC7 and many of its transcriptional targets are human risk loci for IBD and PSC, autoimmune diseases that strikingly resemble the disease we observe in HDAC7 gain-of-function in mice. Importantly, reconstitution of iNKT cells in these mice mitigated their disease, suggesting that the combined defects in negative selection and iNKT cells due to altered HDAC7 function can cause tissue-restricted autoimmunity, a finding that may explain the association between HDAC7 and hepatobiliary autoimmunity.
Assuntos
Autoimunidade , Histona Desacetilases/metabolismo , Células T Matadoras Naturais/imunologia , Animais , Animais Geneticamente Modificados , Deleção de Genes , Expressão Gênica , Humanos , Camundongos , Proteína com Dedos de Zinco da Leucemia Promielocítica/metabolismoRESUMO
How Tregs migrate to GCs, and whether they regulate the helper activity of the T cells in GCs (GC-Th cells) remains poorly understood. We found a T cell subset in human tonsils that displays potent suppressive activities toward GC-Th cell-dependent B cell responses. These Tregs with the surface phenotype of CD4+CD25+CD69- migrate well to CCL19, a chemokine expressed in the T cell zone, but poorly to CXCL13, a chemokine expressed in the B cell zone. This migration toward the T cell-rich zone rapidly changes to trafficking toward B cell follicles upon T cell activation. This change in chemotactic behavior upon activation of T cells is consistent with their switch in the expression of the 2 chemokine receptors CXCR5 and CCR7. CD4+CD25+CD69- Tregs suppress GC-Th cells and GC-Th cell-induced B cell responses such as Ig production, survival, and expression of activation-induced cytosine deaminase. Our results have identified a subset of Tregs that is physiologically relevant to GC-Th cell-dependent B cell responses and a potential regulation mechanism for the trafficking of these Tregs to GCs.
Assuntos
Movimento Celular/fisiologia , Sistema Imunitário/fisiologia , Ativação Linfocitária , Tonsila Palatina/citologia , Subpopulações de Linfócitos T , Linfócitos T/imunologia , Antígenos CD/imunologia , Linfócitos B/imunologia , Quimiocinas/metabolismo , Humanos , Tonsila Palatina/imunologia , Receptores de Quimiocinas/metabolismo , Linfócitos T/citologia , Linfócitos T Auxiliares-Indutores/imunologiaRESUMO
CD4+ T cells differentiate into T helper cell subsets in feedforward manners with synergistic signals from the T cell receptor (TCR), cytokines, and lineage-specific transcription factors. Naive CD4+ T cells avoid spontaneous engagement of feedforward mechanisms but retain a prepared state. T cells lacking the adaptor molecule LAT demonstrate impaired TCR-induced signals yet cause a spontaneous lymphoproliferative T helper 2 (TH2) cell syndrome in mice. Thus, LAT constitutes an unexplained maintenance cue. Here, we demonstrate that tonic signals through LAT constitutively export the repressor HDAC7 from the nucleus of CD4+ T cells. Without such tonic signals, HDAC7 target genes Nur77 and Irf4 are repressed. We reveal that Nur77 suppresses CD4+ T cell proliferation and uncover a suppressive role for Irf4 in TH2 polarization; halving Irf4 gene-dosage leads to increases in GATA3+ and IL-4+ cells. Our studies reveal that naive CD4+ T cells are dynamically tuned by tonic LAT-HDAC7 signals.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Linfócitos T CD4-Positivos/metabolismo , Histona Desacetilases/metabolismo , Fatores Reguladores de Interferon/metabolismo , Proteínas de Membrana/metabolismo , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/metabolismo , Transdução de Sinais , Animais , Núcleo Celular/metabolismo , Proliferação de Células , Deleção de Genes , Regulação da Expressão Gênica , Humanos , Células Jurkat , Camundongos , Fosforilação , Células Th2/imunologiaRESUMO
Ultraviolet (UV) irradiation is a relevant environment factor to induce cellular senescence and photoaging. Both autophagy- and silent information regulator T1 (SIRT1)-dependent pathways are critical cellular processes of not only maintaining normal cellular functions, but also protecting cellular senescence in skin exposed to UV irradiation. In the present studies, we investigated whether modulation of autophagy induction using a novel synthetic SIRT1 activator, heptasodium hexacarboxymethyl dipeptide-12 (named as Aquatide), suppresses the UVB irradiation-induced skin aging. Treatment with Aquatide directly activates SIRT1 and stimulates autophagy induction in cultured human dermal fibroblasts. Next, we found that Aquatide-mediated activation of SIRT1 increases autophagy induction via deacetylation of forkhead box class O (FOXO) 1. Finally, UVB irradiation-induced cellular senescence measured by SA-ß-gal staining was significantly decreased in cells treated with Aquatide in parallel to occurring SIRT1 activation-dependent autophagy. Together, Aquatide modulates autophagy through SIRT1 activation, contributing to suppression of skin aging caused by UV irradiation.
RESUMO
Salicylate and acetylsalicylic acid are potent and widely used anti-inflammatory drugs. They are thought to exert their therapeutic effects through multiple mechanisms, including the inhibition of cyclo-oxygenases, modulation of NF-κB activity, and direct activation of AMPK. However, the full spectrum of their activities is incompletely understood. Here we show that salicylate specifically inhibits CBP and p300 lysine acetyltransferase activity in vitro by direct competition with acetyl-Coenzyme A at the catalytic site. We used a chemical structure-similarity search to identify another anti-inflammatory drug, diflunisal, that inhibits p300 more potently than salicylate. At concentrations attainable in human plasma after oral administration, both salicylate and diflunisal blocked the acetylation of lysine residues on histone and non-histone proteins in cells. Finally, we found that diflunisal suppressed the growth of p300-dependent leukemia cell lines expressing AML1-ETO fusion protein in vitro and in vivo. These results highlight a novel epigenetic regulatory mechanism of action for salicylate and derivative drugs.
Assuntos
Antineoplásicos/farmacologia , Diflunisal/farmacologia , Inibidores Enzimáticos/farmacologia , Regulação Leucêmica da Expressão Gênica , Leucemia Mieloide Aguda/tratamento farmacológico , Ácido Salicílico/farmacologia , Fatores de Transcrição de p300-CBP/antagonistas & inibidores , Acetilcoenzima A/antagonistas & inibidores , Acetilcoenzima A/metabolismo , Acetilação/efeitos dos fármacos , Animais , Antineoplásicos/química , Ligação Competitiva , Domínio Catalítico , Linhagem Celular Tumoral , Subunidade alfa 2 de Fator de Ligação ao Core/genética , Subunidade alfa 2 de Fator de Ligação ao Core/metabolismo , Diflunisal/química , Inibidores Enzimáticos/química , Células HEK293 , Humanos , Leucemia Mieloide Aguda/enzimologia , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Leucócitos/efeitos dos fármacos , Leucócitos/enzimologia , Leucócitos/patologia , Camundongos , Camundongos SCID , Proteínas de Fusão Oncogênica/genética , Proteínas de Fusão Oncogênica/metabolismo , Ligação Proteica , Proteína 1 Parceira de Translocação de RUNX1/genética , Proteína 1 Parceira de Translocação de RUNX1/metabolismo , Ácido Salicílico/química , Transdução de Sinais , Relação Estrutura-Atividade , Ensaios Antitumorais Modelo de Xenoenxerto , Fatores de Transcrição de p300-CBP/genética , Fatores de Transcrição de p300-CBP/metabolismoRESUMO
Cellular senescence permanently arrests cell proliferation, often accompanied by a multi-faceted senescence-associated secretory phenotype (SASP). Loss of mitochondrial function can drive age-related declines in the function of many post-mitotic tissues, but little is known about how mitochondrial dysfunction affects mitotic tissues. We show here that several manipulations that compromise mitochondrial function in proliferating human cells induce a senescence growth arrest with a modified SASP that lacks the IL-1-dependent inflammatory arm. Cells that underwent mitochondrial dysfunction-associated senescence (MiDAS) had lower NAD+/NADH ratios, which caused both the growth arrest and prevented the IL-1-associated SASP through AMPK-mediated p53 activation. Progeroid mice that rapidly accrue mtDNA mutations accumulated senescent cells with a MiDAS SASP in vivo, which suppressed adipogenesis and stimulated keratinocyte differentiation in cell culture. Our data identify a distinct senescence response and provide a mechanism by which mitochondrial dysfunction can drive aging phenotypes.
Assuntos
Senescência Celular , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Adenilato Quinase/metabolismo , Animais , DNA Polimerase gama , DNA Polimerase Dirigida por DNA/metabolismo , Ativação Enzimática , Camundongos , NAD/metabolismo , Fenótipo , Sirtuínas/metabolismo , Proteína Supressora de Tumor p53/metabolismoRESUMO
A population of CD4 T lymphocytes harboring latent HIV genomes can persist in patients on antiretroviral therapy, posing a barrier to HIV eradication. To examine cellular complexes controlling HIV latency, we conducted a genome-wide screen with a pooled ultracomplex shRNA library and in vitro system modeling HIV latency and identified the mTOR complex as a modulator of HIV latency. Knockdown of mTOR complex subunits or pharmacological inhibition of mTOR activity suppresses reversal of latency in various HIV-1 latency models and HIV-infected patient cells. mTOR inhibitors suppress HIV transcription both through the viral transactivator Tat and via Tat-independent mechanisms. This inhibition occurs at least in part via blocking the phosphorylation of CDK9, a p-TEFb complex member that serves as a cofactor for Tat-mediated transcription. The control of HIV latency by mTOR signaling identifies a pathway that may have significant therapeutic opportunities.
Assuntos
Infecções por HIV/virologia , HIV-1/efeitos dos fármacos , HIV-1/genética , Serina-Treonina Quinases TOR/farmacologia , Latência Viral/efeitos dos fármacos , Proteínas Adaptadoras de Transdução de Sinal/genética , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD4-Positivos/virologia , Linhagem Celular , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Quinase 9 Dependente de Ciclina/metabolismo , Regulação Viral da Expressão Gênica , Técnicas de Silenciamento de Genes , Genes Virais , HIV-1/fisiologia , Humanos , Células K562 , Fosforilação , Fator B de Elongação Transcricional Positiva/metabolismo , RNA Interferente Pequeno/genética , Transdução de Sinais , Serina-Treonina Quinases TOR/genética , Serina-Treonina Quinases TOR/metabolismo , Transcrição Gênica/efeitos dos fármacos , Homólogo LST8 da Proteína Associada a mTOR , Produtos do Gene tat do Vírus da Imunodeficiência HumanaRESUMO
BACKGROUND: The function of CD57+ CD4+ T cells, constituting a major subset of germinal center T (GC-Th) cells in human lymphoid tissues, has been unclear. There have been contradictory reports regarding the B cell helping function of CD57+ GC-Th cells in production of immunoglobulin (Ig). Furthermore, the cytokine and co-stimulation requirement for their helper activity remains largely unknown. To clarify and gain more insight into their function in helping B cells, we systematically investigated the capacity of human tonsil CD57+ GC-Th cells in inducing B cell Ig synthesis. RESULTS: We demonstrated that CD57+ GC-Th cells are highly efficient in helping B cell production of all four subsets of Ig (IgM, IgG, IgA and IgE) compared to other T-helper cells located in germinal centers or interfollicular areas. CD57+ GC-Th cells were particularly more efficient than other T cells in helping GC-B cells but not naive B cells. CD57+ GC-Th cells induced the expression of activation-induced cytosine deaminase (AID) and class switch recombination in developing B cells. IgG1-3 and IgA1 were the major Ig isotypes induced by CD57+ GC-Th cells. CD40L, but not IL-4, IL-10 and IFN-gamma, was critical in CD57+ GC-Th cell-driven B cell production of Ig. However, IL-10, when added exogenously, significantly enhanced the helper activity of CD57+ GC-Th cells, while TGF-beta1 completely and IFN-gamma partially suppressed the CD57+ GC-Th cell-driven Ig production. CONCLUSIONS: CD57+CD4+ T cells in the germinal centers of human lymphoid tissues are the major T helper cell subset for GC-B cells in Ig synthesis. Their helper activity is consistent with their capacity to induce AID and class switch recombination, and can be regulated by CD40L, IL-4, IL-10 and TGF-beta.
Assuntos
Subpopulações de Linfócitos B/imunologia , Linfócitos T CD4-Positivos/imunologia , Antígenos CD57/análise , Centro Germinativo/citologia , Switching de Imunoglobulina/fisiologia , Subpopulações de Linfócitos T/imunologia , Formação de Anticorpos/efeitos dos fármacos , Formação de Anticorpos/imunologia , Antígenos CD/análise , Antígenos de Diferenciação de Linfócitos T/análise , Centro Germinativo/imunologia , Humanos , Isotipos de Imunoglobulinas/biossíntese , Interferon gama/farmacologia , Interleucina-10/farmacologia , Interleucina-4/farmacologia , Lectinas Tipo C , Cooperação Linfocítica/efeitos dos fármacos , Tonsila Palatina/citologiaRESUMO
The balance of effector and regulatory T cell function, dependent on multiple signals and epigenetic regulators, is critical to immune self-tolerance. Dysregulation of T helper 17 (Th17) effector cells is associated with multiple autoimmune diseases, including multiple sclerosis. Here, we report that Sirtuin 1 (SIRT1), a protein deacetylase previously reported to have an antiinflammatory function, in fact promotes autoimmunity by deacetylating RORγt, the signature transcription factor of Th17 cells. SIRT1 increases RORγt transcriptional activity, enhancing Th17 cell generation and function. Both T cell-specific Sirt1 deletion and treatment with pharmacologic SIRT1 inhibitors suppress Th17 differentiation and are protective in a mouse model of multiple sclerosis. Moreover, analysis of infiltrating cell populations during disease induction in mixed hematopoietic chimeras shows a marked bias against Sirt1-deficient Th17 cells. These findings reveal an unexpected proinflammatory role of SIRT1 and, importantly, support the possible therapeutic use of SIRT1 inhibitors against autoimmunity.
Assuntos
Diferenciação Celular/imunologia , Esclerose Múltipla/imunologia , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/imunologia , Sirtuína 1/imunologia , Células Th17/imunologia , Transcrição Gênica/imunologia , Acetilação , Animais , Diferenciação Celular/genética , Modelos Animais de Doenças , Camundongos , Camundongos Knockout , Esclerose Múltipla/genética , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/genética , Sirtuína 1/genética , Células Th17/patologia , Transcrição Gênica/genéticaRESUMO
It is a question of interest whether Th17 cells express trafficking receptors unique to this Th cell lineage and migrate specifically to certain tissue sites. We found several Th17 cell subsets at different developing stages in a human secondary lymphoid organ (tonsils) and adult, but not in neonatal, blood. These Th17 cell subsets include a novel in vivo-stimulated tonsil IL17+ T cell subset detected without any artificial stimulation in vitro. We investigated in depth the trafficking receptor phenotype of the Th17 cell subsets in tonsils and adult blood. The developing Th17 cells in tonsils highly expressed both Th1- (CCR2, CXCR3, CCR5, and CXCR6) and Th2-associated (CCR4) trafficking receptors. Moreover, Th17 cells share major non-lymphoid tissue trafficking receptors, such as CCR4, CCR5, CCR6, CXCR3, and CXCR6, with FOXP3+ T regulatory cells. In addition, many Th17 cells express homeostatic chemokine receptors (CD62L, CCR6, CCR7, CXCR4, and CXCR5) implicated in T cell migration to and within lymphoid tissues. Expression of CCR6 and CCR4 by some Th17 cells is not a feature unique to Th17 cells but shared with FOXP3+ T cells. Interestingly, the IL17+IFN-gamma+ Th17 cells have the features of both IL17-IFN-gamma+ Th1 and IL17+IFN-gamma- Th17 cells in expression of trafficking receptors. Taken together, our results revealed that Th17 cells are highly heterogeneous, in terms of trafficking receptors, and programmed to share major trafficking receptors with other T cell lineages. These findings have important implications in their distribution in the human body in relation to other regulatory T cell subsets.
Assuntos
Interleucina-17/metabolismo , Subpopulações de Linfócitos T/imunologia , Linfócitos T Auxiliares-Indutores/imunologia , Linfócitos T Reguladores/imunologia , Células Cultivadas , Sangue Fetal/imunologia , Fatores de Transcrição Forkhead/análise , Humanos , Tonsila Palatina/imunologia , Receptores de Quimiocinas/análise , Receptores de Quimiocinas/metabolismoRESUMO
IL-7 plays important roles in development and homeostatic proliferation of lymphocytes. IL-7 uses a receptor composed of IL-7Ralpha (CD127) and the common gamma-chain (CD132) to transmit its signal. It has been unknown how CD127 is regulated during Th cell differentiation to the B cell-helping T cell lineage. In this study, we report that loss of CD127 defines terminally differentiated B cell-helping effector T cells in human tonsils. Although naive CD4(+) T cells uniformly express CD127, the memory/effector (non-FOXP3(+)) CD4(+) T cells are divided into CD127(+) and CD127(-) cells. The CD127(-) T cells are exclusively localized within the germinal centers where B cells become plasma and memory B cells, whereas CD127(+) T cells are found in T cell areas and the area surrounding B cell follicles. Consistently, the CD127(-) T cells highly express the B cell zone homing receptor CXCR5 with concomitant loss of CCR7. Compared with CD127(+) memory T cells, CD127(-) T cells have considerably shorter telomeres, do not proliferate in response to IL-7, and are prone to cell death. The CD127(-) T cells produce a large amount of the B cell follicle-forming chemokine CXCL13 upon stimulation with B cells and Ags. Most importantly, they are highly efficient in helping B cells produce Igs of all isotypes in a manner dependent on CD40L and ICOS and inducing activation-induced cytidine deaminase and Ig class switch recombination. The selective loss of CD127 on the B cell-helping effector T cells would have implications in regulation and termination of Ig responses.
Assuntos
Linfócitos B/imunologia , Linfócitos T CD4-Positivos/imunologia , Diferenciação Celular/imunologia , Tonsila Palatina/imunologia , Receptores de Interleucina-7/fisiologia , Linfócitos T Auxiliares-Indutores/imunologia , Adolescente , Citocinas/imunologia , Fatores de Transcrição Forkhead/metabolismo , Humanos , Imunofenotipagem , Receptores CCR7/biossíntese , Receptores CXCR5/biossínteseRESUMO
In this study, we report a novel biological function of vitamin A metabolites in conversion of naive FoxP3- CD4+ T cells into a unique FoxP3+ regulatory T cell subset (termed "retinoid-induced FoxP3+ T cells") in both human and mouse T cells. We found that the major vitamin A metabolite all-trans-retinoic acid induces histone acetylation at the FoxP3 gene promoter and expression of the FoxP3 protein in CD4+ T cells. The induction of retinoid-induced FoxP3+ T cells is mediated by the nuclear retinoic acid receptor alpha and involves T cell activation driven by mucosal dendritic cells and costimulation through CD28. Retinoic acid can promote TGF-beta1-dependent generation of FoxP3+ regulatory T cells but decrease the TGF-beta1- and IL-6-dependent generation of inflammatory Th17 cells in mouse T cells. Retinoid-induced FoxP3+ T cells can efficiently suppress target cells and, thus, have a regulatory function typical for FoxP3+ T cells. A unique cellular feature of these regulatory T cells is their high expression of gut-homing receptors that are important for migration to the mucosal tissues particularly the small intestine. Taken together, these results identify retinoids as positive regulatory factors for generation of gut-homing FoxP3+ T cells.
Assuntos
Movimento Celular/imunologia , Fatores de Transcrição Forkhead/biossíntese , Mucosa Intestinal/citologia , Mucosa Intestinal/imunologia , Linfócitos T Reguladores/citologia , Linfócitos T Reguladores/imunologia , Tretinoína/fisiologia , Vitamina A/metabolismo , Animais , Movimento Celular/genética , Células Cultivadas , Técnicas de Cocultura , Inibidores do Crescimento/metabolismo , Inibidores do Crescimento/fisiologia , Humanos , Imunofenotipagem , Interleucina-6/antagonistas & inibidores , Interleucina-6/fisiologia , Mucosa Intestinal/metabolismo , Tecido Linfoide/citologia , Tecido Linfoide/imunologia , Tecido Linfoide/metabolismo , Camundongos , Camundongos Endogâmicos AKR , Camundongos Endogâmicos BALB C , Receptores de Retorno de Linfócitos/metabolismo , Receptores de Retorno de Linfócitos/fisiologia , Receptores do Ácido Retinoico/biossíntese , Receptores do Ácido Retinoico/fisiologia , Receptor alfa de Ácido Retinoico , Linfócitos T Auxiliares-Indutores/classificação , Linfócitos T Auxiliares-Indutores/citologia , Linfócitos T Reguladores/metabolismo , Fator de Crescimento Transformador beta1/antagonistas & inibidores , Fator de Crescimento Transformador beta1/fisiologia , Tretinoína/metabolismo , Vitamina A/fisiologia , Receptor gama de Ácido RetinoicoRESUMO
BACKGROUND AND AIMS: It has been unclear which chemokine network is involved in migration of T-cell subsets to chronically inflamed lesions of the intestine. SAMP1/YP mice develop a spontaneous chronic transmural intestinal lesion specifically in the ileum. Using these mice, we investigated the gut chemokine network involved in specific migration of T-cell subsets to the inflamed lesion of the intestine. METHODS: We performed expression analyses of chemokines and their receptors, chemokine receptor blocking studies, and migration studies in vitro and in vivo to identify the gut chemokine network induced in intestinal inflammation and to determine its role in migration of conventional and FoxP3(+) suppressor T cells to the inflamed intestine. RESULTS: The expression of homeostatic chemokines was largely unchanged in the inflamed lesion of SAMP1/YP mice compared with control mice. However, an additional chemokine axis (CCL5-CCR5) was up-regulated in the inflamed intestine of SAMP1/YP mice compared with control mice. Activated T cells of SAMP1/YP mice compared with control mice were hyperresponsive to CCL5 in chemotaxis. CCR5(+) T cells preferentially migrated to the inflamed lesion, which can be blocked by a CCR5 antagonist. Importantly, the FoxP3(+) regulatory T cells of the inflamed lesion of SAMP1/YP mice highly expressed CCR5. CCR5 blockade suppressed the migration of FoxP3(+) T cells into the inflamed intestine and significantly exacerbated the intestinal inflammation. CONCLUSIONS: The CCL5-CCR5 chemokine axis is involved in preferential recruitment of FoxP3(+) regulatory T cells, which prevents further exacerbation of chronic inflammation in the intestine.