The activin-follistatin system: Key regulator of kidney development, regeneration, inflammation, and fibrosis.

Activins, multifunctional cytokines of the transforming growth factor-beta superfamily, play critical roles in the regulation of growth and differentiation in multiple biological systems. Activin activity is finely regulated by the endogenous antagonist follistatin. Early studies reported that activins are involved in renal organogenesis, but subsequent research demonstrated that activins also play a significant role in kidney regeneration following injury. The results of more recent studies suggest activins play roles in both inflammatory kidney diseases and renal fibrosis, conditions that often culminate in end-stage renal disease. Given these findings, the inhibition of activin activity represents a promising therapeutic approach for treating a range of kidney disorders. This review discusses the latest discoveries concerning the role of the activin-follistatin system in renal development and pathophysiology and explores the potential therapeutic implications of targeting this system in the management of kidney diseases.