RESUMO
Activins and inhibins are members of the transforming growth factor-ß superfamily that have been considered crucial regulators of cell processes, such as differentiation, proliferation and apoptosis, in different cell types. Initial studies about the function of activin A in the immune system focused on the regulation of hematopoiesis in the bone marrow under homeostatic and inflammatory conditions. Recent data provide a more comprehensive understanding about the role of activins/inhibins in the immune system. Novel findings included in this review point out the important requirement of activin/inhibin signaling to maintain the balance between homeostatic and inflammatory signals that are required for the optimal development and function of immune cells. The purpose of this review is to highlight the versatile nature of activins/inhibins as key regulators of both the innate and adaptive immune responses.
Assuntos
Ativinas/imunologia , Imunidade Adaptativa , Imunidade Inata , Inibinas/imunologia , Transdução de Sinais/fisiologia , Ativinas/metabolismo , Animais , Medula Óssea/metabolismo , Hematopoese/fisiologia , Humanos , Inibinas/metabolismo , Leucócitos/imunologia , Camundongos , Fagócitos/imunologia , Fator de Crescimento Transformador beta/metabolismoRESUMO
Members of the transforming growth factor beta (TGF-beta) superfamily are soluble factors that regulate a variety of functional responses including proliferation, differentiation, apoptosis and cell cycle, among others, depending not only on the cell type and its differentiation state, but also on the milieu of cytokines present. All three members of this superfamily: TGF-betas, bone morphogenetic proteins (BMPs) and Activins, have been shown to be expressed in the thymus suggesting their potential role as regulators of the T lymphocyte differentiation process. Although initial reports described the role of TGF-beta in controlling specific checkpoints during thymocyte development, recent data has provided new evidence on the role of BMPs and Activins in this process. This review provides new insights on the function of members of the TGF-beta superfamily at different stages of thymocyte development.