The potential role of IL‐33/ST2 signaling in fibrotic diseases

Review on the biological characteristics of IL‐33 and the role of the IL‐33/ST2 signaling pathway in various fibrotic diseases. IL‐33, a new member of the IL‐1F, is widely expressed throughout the body and can be up‐regulated by stimulation with proinflammatory factors. It has been identified as a functional ligand for the plasma membrane receptor complex that is a heterodimer consisting of membrane‐bound ST2L, which is a member of the IL‐1R family, and IL‐1RAcP. IL‐33 is crucial for the induction of Th2 immune responses. Additionally, under other circumstances, it can also act as an endogenous danger signal. Recently, many studies have demonstrated that IL‐33 may be related to the development and progression of fibrotic diseases. It has proinflammatory effects in some fibrotic diseases but has anti‐inflammatory effects in others. In this review, the biologic characteristics of IL‐33 and the role of the IL‐33/ST2 signaling pathway in various fibrotic diseases will be discussed. We hope this overview will provide new insights for the treatment of these diseases.