Baicalin protects against renal interstitial fibrosis in mice by inhibiting the TGF-β/Smad signalling pathway

CONTEXT: Baicalin, a flavonoid extracted from radix scutellariae, possesses various pharmacological effects, including protective effects on renal interstitial fibrosis (RIF), but its possible role and mechanisms have not been fully elucidated. OBJECTIVE: This study explores the protective effects and mechanisms of baicalin on RIF. MATERIALS AND METHODS: C57BL/6 male mice were divided into six groups: sham, model, low baicalin, middle baicalin, high baicalin and positive drug groups. The unilateral ureteral obstruction (UUO) model of RIF was constructed and treated with baicalin doses (10, 20 and 40 mg/kg) and a positive control drug (valsartan, 8 mg/kg). H&E staining was used to observe the pathological changes in renal tissues, Masson staining was performed to evaluate collagen deposition in renal tissues, and immunohistochemical examination was adopted to determine α-SMA and extracellular matrix (ECM) expression. Primary mouse fibroblasts were isolated, extracted and treated with baicalin and/or TGF-β. qRT-PCR and enzyme-linked immunosorbent assay (ELISA) were applied to detect the inflammatory responses. Moreover, ECM and TGF-β/Smad expression levels were evaluated by western blot assay. RESULTS: Baicalin ameliorated RIF in UUO mice by inhibiting fibrosis and inflammatory responses. The TGF-β/Smad pathway was significantly suppressed in the UUO mouse model. Additionally, baicalin significantly inhibited ECM expression and inflammatory factors in fibroblasts treated with TGF-β. TGF-β/Smad pathway activation was significantly decreased in fibroblasts. DISCUSSION AND CONCLUSIONS: These findings support the use of baicalin as a potential therapeutic option for the treatment of RIF by possibly inhibiting the TGF-β/Smad signalling pathway.