Background: Systemic sclerosis (SSc) is a connective tissue fibrotic disease for which there is no effective treatment. Traditional Chinese Medicine (TCM), such as the Yiqihuoxue formula used in Shanghai TCM-integrated Hospital, has shown the efficacy of anti-fibrosis in clinical applications. This study was aiming to dissect the anti-fibrotic mechanism of Yiqihuoxue treatment for SSc.
Methods: Bleomycin-induced mice and SSc dermal fibroblasts were treated with Yiqihuoxue decoction; NIH-3T3 fibroblasts were exposed to exogenous TGF-β1, and then cultured with or without Yiqihuoxue decoction. Luciferase reporter gene assay was used to determine the activity of Smad binding element (SBE). Quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to examine the mRNA levels of extracellular matrix (ECM) genes. The protein levels of type I collagen, Smad3 and phosphorylated-Smad3 (p-Smad3) were detected by western blotting. Student's t-tests were used to determine the significance of the results.
Results: Bleomycin-induced mice, SSc dermal fibroblasts and TGF-β1-induced NIH/3T3 fibroblasts showed higher levels of ECM gene transcriptions and collagen production. In addition, the phosphorylation level of Smad3 and activity of SBE were significantly increased after exogenous TGF-β1 induction. Whereas, Yiqihuoxue treatment could obviously attenuate fibrosis in bleomycin-induced mice, down regulate ECM gene expressions and collagen production in SSc dermal fibroblasts and TGF-β1-induced NIH/3T3 fibroblasts. Furthermore, the aberrantly high phosphorylation level of Smad3 and activity of SBE in the TGF-β1-induced NIH/3T3 fibroblasts were also dramatically decreased by Yiqihuoxue treatment.
Conclusions: Yiqihuoxue treatment could effectively reduce collagen production via down-regulating the phosphorylation of Smad3 and then the activity of SBE, which are involved in the TGF-β pathway and constitutively activated in the progression of SSc.