RESUMO
T follicular helper (Tfh) cell is a unique T cell subset specialized in promoting humoral immunity. B-cell lymphoma 6 protein (Bcl6) has been identified as an obligatory transcription factor in Tfh cells; however, the molecular mechanism underlying Bcl6 function remains largely unknown. Here, we defined Bcl6 target genes in Tfh cells by analyzing genome-wide Bcl6 occupancy together with transcriptome profiling. With consensus sequences being different from those in Th9, B cells, and macrophages, Bcl6 binding in Tfh cell was closely associated with a decrease in 5-hydroxymethylcytosine (5hmC). Importantly, Bcl6 promoted Tfh cell differentiation through antagonizing IL-7R (CD127)/signal transducer and activator of transcription (STAT) 5 axis; deletion of the Bcl6 gene in T cells resulted in enhanced IL-7R-STAT5 signaling and substantial expansion of CD127(hi) non-Tfh cells. Thus, our study systemically examines Bcl6-controlled regulatory networks and provides important insights into Bcl6's biological functions in Tfh cells.
Assuntos
Proteínas de Ligação a DNA/genética , Redes Reguladoras de Genes/imunologia , Receptores de Interleucina-7/genética , Fator de Transcrição STAT5/genética , Linfócitos T Auxiliares-Indutores/imunologia , 5-Metilcitosina/análogos & derivados , Animais , Linfócitos B/citologia , Linfócitos B/imunologia , Sequência de Bases , Diferenciação Celular , Citosina/análogos & derivados , Citosina/imunologia , Proteínas de Ligação a DNA/imunologia , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Estudo de Associação Genômica Ampla , Centro Germinativo/citologia , Centro Germinativo/imunologia , Interleucina-4/genética , Interleucina-4/imunologia , Interleucinas/genética , Interleucinas/imunologia , Macrófagos/citologia , Macrófagos/imunologia , Camundongos , Camundongos Transgênicos , Dados de Sequência Molecular , Proteínas Proto-Oncogênicas c-bcl-6 , Receptores de Interleucina-7/imunologia , Fator de Transcrição STAT5/imunologia , Transdução de Sinais , Linfócitos T Auxiliares-Indutores/citologiaRESUMO
The interleukin-17 (IL-17) family of cytokines has emerged as a critical player in inflammatory diseases. Among them, IL-25 has been shown to be important in allergic inflammation and protection against parasitic infection. Here we have demonstrated that IL-17B, a poorly understood cytokine, functions to inhibit IL-25-driven inflammation. IL-17B and IL-25, both binding to the interleukin-17 receptor B (IL-17RB), were upregulated in their expression after acute colonic inflammation. Individual inhibition of these cytokines revealed opposing functions in colon inflammation: IL-25 was pathogenic but IL-17B was protective. Similarly opposing phenotypes were observed in Citrobacter rodentium infection and allergic asthma. Moreover, IL-25 was found to promote IL-6 production from colon epithelial cells, which was inhibited by IL-17B. Therefore, our data demonstrate that IL-17B is an anti-inflammatory cytokine in the IL-17 family.
Assuntos
Asma/imunologia , Colite/imunologia , Disbiose/imunologia , Infecções por Enterobacteriaceae/imunologia , Interleucina-17/imunologia , Interleucinas/imunologia , Mucosa Intestinal/imunologia , Animais , Antibacterianos , Asma/induzido quimicamente , Asma/genética , Asma/patologia , Linhagem Celular , Citrobacter rodentium/imunologia , Colite/induzido quimicamente , Colite/genética , Colite/patologia , Disbiose/induzido quimicamente , Disbiose/genética , Disbiose/patologia , Infecções por Enterobacteriaceae/genética , Infecções por Enterobacteriaceae/microbiologia , Infecções por Enterobacteriaceae/patologia , Células Epiteliais/imunologia , Células Epiteliais/patologia , Regulação da Expressão Gênica , Interleucina-17/deficiência , Interleucina-17/genética , Interleucina-6/genética , Interleucina-6/imunologia , Interleucinas/deficiência , Interleucinas/genética , Mucosa Intestinal/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Ovalbumina , Ligação Proteica , Receptores de Interleucina-17/genética , Receptores de Interleucina-17/imunologia , Transdução de Sinais , Dodecilsulfato de SódioRESUMO
Members of the MAPK phosphatase (MKP) protein family play critical roles in immune responses through differential regulation of MAPK activation. In this study, we show that MKP7, also known as dual-specificity phosphatase 16, was required for CD4(+) T cell responses in vivo. Mkp7(-/-) CD4(+) T cells exhibited enhanced ERK and JNK activation, and produced increased amount of IL-2 compared with Mkp7(+/+) cells upon activation. Mkp7(-/-) CD4(+) T cells were selectively defective in Th17 differentiation in vitro, which was rescued by blocking IL-2 or inhibition of ERK activation. Furthermore, mice carrying Mkp7(-/-) T cells were deficient in generation of Th17 and T follicular helper cells in vivo, and were resistant to autoimmune experimental encephalomyelitis. Our results thus demonstrate an essential role of MKP7 in effector T cell function.
Assuntos
Diferenciação Celular/genética , Fosfatases de Especificidade Dupla/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Regulação da Expressão Gênica , Interleucina-2/genética , Fosfatases da Proteína Quinase Ativada por Mitógeno/genética , Linfócitos T/citologia , Linfócitos T/metabolismo , Animais , Autoimunidade/genética , Autoimunidade/imunologia , Fosfatases de Especificidade Dupla/deficiência , Fosfatases de Especificidade Dupla/metabolismo , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/imunologia , Genes Letais , Interleucina-2/metabolismo , Ativação Linfocitária/imunologia , Camundongos , Camundongos Transgênicos , Fosfatases da Proteína Quinase Ativada por Mitógeno/deficiência , Fosfatases da Proteína Quinase Ativada por Mitógeno/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Subpopulações de Linfócitos T/citologia , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Linfócitos T/imunologia , Células Th17/citologia , Células Th17/imunologia , Células Th17/metabolismoRESUMO
In the IL-17 family of cytokines, much is known about the sources and functions of IL-17, IL-17F, and IL-25 in the host defense against infection and in inflammatory diseases; however, the physiological function of IL-17C remains poorly understood. Using mice deficient in IL-17C, we demonstrate that this cytokine is crucial for the regulation of an acute experimental colitis elicited by dextran sulfate sodium. In this model, mice lacking IL-17C exhibited exacerbated disease that was associated with increased IL-17 expression by γδ T cells and Th17 cells. Moreover, IL-17C directly regulated the expression of the tight junction molecule occludin by colonic epithelial cells. Thus, our data suggest that IL-17C plays a critical role in maintaining mucosal barrier integrity.
Assuntos
Colite/imunologia , Colite/patologia , Mediadores da Inflamação/fisiologia , Interleucina-17/fisiologia , Mucosa Intestinal/imunologia , Mucosa Intestinal/patologia , Animais , Linhagem Celular , Colite/genética , Colo/citologia , Colo/imunologia , Colo/patologia , Sulfato de Dextrana/toxicidade , Modelos Animais de Doenças , Epitélio/imunologia , Epitélio/metabolismo , Epitélio/patologia , Predisposição Genética para Doença , Mediadores da Inflamação/metabolismo , Interleucina-17/biossíntese , Interleucina-17/deficiência , Mucosa Intestinal/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos KnockoutRESUMO
Cytokines and transcription factors play key roles in dendritic cell (DC) development, yet information about regulatory interactions between these signals remains limited. Here we show that the cytokines GM-CSF and Flt3L induce the transcriptional mediators Id2 and E2-2 and control DC lineage diversification by STAT-dependent pathways. We found that STAT5 is required for tissue CD103(+) DC generation and plasmacytoid DC (pDC) suppression in steady state or response to GM-CSF. STAT5 stimulates GM-CSF-dependent expression of Id2, which controls CD103(+) DC production and pDC inhibition. By contrast, pDCs, but not CD103(+) DCs, are dependent on STAT3. Consistently, STAT3 stimulates Flt3L-responsive expression of the pDC regulator Tcf4 (E2-2). These data suggest that STATs contribute to DC development by controlling transcription factors involved in lineage differentiation.
Assuntos
Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Diferenciação Celular/genética , Células Dendríticas/fisiologia , Proteína 2 Inibidora de Diferenciação/genética , Fator de Transcrição STAT3/fisiologia , Fator de Transcrição STAT5/fisiologia , Animais , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Células Dendríticas/efeitos dos fármacos , Células Dendríticas/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacologia , Proteína 2 Inibidora de Diferenciação/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Biológicos , Regiões Promotoras Genéticas/efeitos dos fármacos , Regiões Promotoras Genéticas/genética , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo , Fator de Transcrição STAT5/genética , Fator de Transcrição STAT5/metabolismo , Fator de Transcrição 4RESUMO
BACKGROUND: Francisella tularensis is a Gram-negative facultative intracellular bacterium and the causative agent of the lethal disease tularemia. An outer membrane protein (FTT0918) of F. tularensis subsp. tularensis has been identified as a virulence factor. We generated a F. novicida (F. tularensis subsp. novicida) FTN_0444 (homolog of FTT0918) fopC mutant to study the virulence-associated mechanism(s) of FTT0918. METHODS AND FINDINGS: The ΔfopC strain phenotype was characterized using immunological and biochemical assays. Attenuated virulence via the pulmonary route in wildtype C57BL/6 and BALB/c mice, as well as in knockout (KO) mice, including MHC I, MHC II, and µmT (B cell deficient), but not in IFN-γ or IFN-γR KO mice was observed. Primary bone marrow derived macrophages (BMDM) prepared from C57BL/6 mice treated with rIFN-γ exhibited greater inhibition of intracellular ΔfopC than wildtype U112 strain replication; whereas, IFN-γR KO macrophages showed no IFN-γ-dependent inhibition of ΔfopC replication. Moreover, phosphorylation of STAT1 was downregulated by the wildtype strain, but not the fopC mutant, in rIFN-γ treated macrophages. Addition of NG-monomethyl-L-arginine, an NOS inhibitor, led to an increase of ΔfopC replication to that seen in the BMDM unstimulated with rIFN-γ. Enzymatic screening of ΔfopC revealed aberrant acid phosphatase activity and localization. Furthermore, a greater abundance of different proteins in the culture supernatants of ΔfopC than that in the wildtype U112 strain was observed. CONCLUSIONS: F. novicida FopC protein facilitates evasion of IFN-γ-mediated immune defense(s) by down-regulation of STAT1 phosphorylation and nitric oxide production, thereby promoting virulence. Additionally, the FopC protein also may play a role in maintaining outer membrane stability (integrity) facilitating the activity and localization of acid phosphatases and other F. novicida cell components.
