Interplay between microRNAs and TGF-β signaling in T cells: implications for Th9 differentiation and immune pathogenesis

Since the discovery of microRNAs (miRNAs) in 1993, they have been established as key post-transcriptional regulators of immune cell function. In particular, miRNAs have emerged as key modulators of CD4+ T cell activation and differentiation. Accumulating evidence indicates that miRNAs influence CD4+ T cell fate through modulating transforming growth factor β (TGF-β) signaling, which negatively regulates T helper (Th) 1 and Th2 cell differentiation, while promoting the generation of regulatory T (Treg) cells, Th17 as well as Th9 cells. Despite these advances, our understanding of specific roles of miRNAs and their target molecules in CD4+ T cells remains limited, particularly in Th9 cells. In this review, we discuss the regulatory networks of miRNAs targeting the TGF-β signaling pathway in CD4+ T cells, with a special focus on their roles in Th9 cell differentiation and function.