Indirubin alleviates bleomycin-induced pulmonary fibrosis in mice by suppressing fibroblast to myofibroblast differentiation
Qi Wang, Jun Yu, Yinan Hu, Xueying Chen, Lei Zhang, Ting Pan, Kang Miao, Yong Mou, Yongjian Xu, Weining Xiong, Yi Wang
Abstract
BACKGROUND AND OBJECTIVE: Idiopathic pulmonary fibrosis (IPF) is a chronic fibrosing interstitial lung disease with a poor prognosis. Indirubin, a compound obtained from indigo-bearing plants or mollusks of the family Muricidae, has various bioactivities, including anti-tumor activity and anti-inflammation effect. However, whether indirubin could mediate its therapeutic effects on bleomycin (BLM)-induced pulmonary fibrosis has not been addressed. METHODS: The impacts of indirubin on bleomycin (BLM)-induced pulmonary fibrosis were evaluated by pathological staining, western blot, RT-PCR and immunofluorescent staining. The effects of indirubin on fibroblast differentiation and related signaling were next investigated to demonstrate the underlying mechanisms. RESULTS: The results indicated that indirubin-treated mice exhibited a definitively improved survival rate than that of the BLM-induced mice in a dose-depend manner. Additionally, administration of indirubin significantly alleviated inflammatory cells infiltration in BLM mice. Importantly, indirubin provided protection for mice against BLM-induced pulmonary fibrosis as manifested by the attenuating expression of fibrotic hallmarks, including fibronectin, collagen I and α-smooth muscle actin (α-SMA). Subsequently, we providedin vitro evidence revealing that indirubin suppressed fibroblast to myofibroblast differentiation by repressed TGF-β/Smad signaling in a dose-dependent manner. Notably, our data showed that indirubin seemed to be safe in mice and fibroblasts. CONCLUSION: Overall, indirubin could protect the mice against BLM-induced pulmonary fibrosis by alleviated fibroblast differentiation and may be therapeutically beneficial for IPF patients.