Revisiting the regulatory roles of the TGF-β family of cytokines.

TGF-β family members are multipotent cytokines that are involved in many cellular processes, including cell differentiation, organ development, wound healing and immune regulation. TGF-β has pleiotropic effects on adaptive immunity, especially in the regulation of CD4(+) T cell and B cell responses. Furthermore, identification of CD4(+) T cell subsets that produce TGF-β3 revealed unexpected roles of TGF-β3 in the control of adaptive immunity. In contrast to TGF-β1, which induces extensive fibrosis, TGF-β3 induces non-scarring wound healing and counteracts tissue fibrosis. Recent progress in the understanding of the activation mechanism of TGF-β may enable us to develop novel biologic therapies based on advanced protein engineering.