RESUMO
Interleukin 27 (IL-27) has been identified as a potent cytokine in the differentiation of type 1 regulatory T (Tr1) cells through interactions with several key elements, including transcription factors such as aryl hydrocarbon receptor and IL-21. Autocrine production of IL-21 is known to be important for maintaining IL-10 expression by Tr1 cells. Although previous studies have shown that the phosphoinositide 3-kinase (PI3K) -Akt axis contributes to the differentiation of helper T-cell subsets, the role of the PI3K pathway on Tr1 cell differentiation remains to be elucidated. Here, we demonstrate that suppression of the PI3K-Akt pathway results in impairment of IL-27-induced Tr1 (IL-27-Tr1) cell differentiation in vitro and in vivo. Furthermore, this suppression down-regulates IL-21 receptor expression by Tr1 cells, followed by suppression of IL-10 expression by IL-27-Tr1 cells. These results suggest that the PI3K pathway enhances IL-10 expression by IL-27-Tr1 cells through up-regulation of IL-21 receptors.
Assuntos
Diferenciação Celular/efeitos dos fármacos , Interleucina-27/farmacologia , Fosfatidilinositol 3-Quinase/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/efeitos dos fármacos , Linfócitos T Reguladores/efeitos dos fármacos , Animais , Células Cultivadas , Feminino , Proteína Forkhead Box O1/imunologia , Proteína Forkhead Box O1/metabolismo , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Genótipo , Interleucina-10/genética , Interleucina-10/metabolismo , Subunidade alfa de Receptor de Interleucina-21/imunologia , Subunidade alfa de Receptor de Interleucina-21/metabolismo , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fenótipo , Inibidores de Fosfoinositídeo-3 Quinase , Fosforilação , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-akt/genética , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismoRESUMO
Transforming growth factor-ß (TGF-ß) is a pivotal cytokine in the differentiation of regulatory T cells, and Foxo transcription factors positively regulate this process. On the other hand, the function of Foxo transcription factors is negatively regulated by PI3K/Akt signaling, which is activated by TGF-ß in many types of cells; yet the role of TGF-ß in Akt activity and its downstream substrates in CD4+ T cells, including Foxo transcription factors, remains to be determined. Herein, we demonstrate that TGF-ß selectively induces Akt phosphorylation at Ser473 but not at Thr308 in a class IA PI3K-dependent manner in CD4+ T cells, resulting in the phosphorylation and inhibition of Foxo transcription factors and negatively regulating the differentiation of induced regulatory T cells (iTregs). These observations reveal a novel negative regulatory mechanism involving Akt and Foxo transcription factors induced by TGF-ß in the iTreg differentiation process.