Tiaoshen Tongluo Attenuates Fibrosis by Modulating the TGF-β1/Smad Pathway in Endometrial Stromal Cells and a Rat Model of Intrauterine Adhesion

Intrauterine adhesion (IUA) is a serious complication caused by excessive fibrosis resulting from endometrial repair after trauma. The traditional Chinese medicine Tiaoshen Tongluo recipe (TTR) contains ingredients associated with the alleviation of fibrosis. The transforming growth factor-β1 (TGF-β1)/Smad pathway is thought to mediate fibrosis in IUA. In this study, we evaluated the influence of TTR on endometrial fibrosis in a rat model of IUA and in TGF-β1-stimulated endometrial stromal cells (ESCs). TTR was found to alleviate the level of endometrial fibrosis in a rat model of IUA. A higher number of collagen fibers and greater damage were observed in the endometrial tissue of untreated rats compared to those treated with TTR. The expression of TGF-β1, Smad2, Smad3, and Smad4 was upregulated following IUA, whereas Smad7 expression was downregulated. TTR lowers the expression of TGF-β1, Smad2, Smad3, and Smad4 but increases the expression of Smad7 in vivo, indicating that TTR can modulate the expression of the TGF-β1/Smad pathway to mediate fibrosis. In ESCs, the phosphorylation of Smad2 and Smad3 and upregulation of Smad4 were induced by TGF-β1 whereas the expression of Smad7 was inhibited. Administration of TTR reduces the phosphorylation of Smad2 and Smad3, increases Smad4 expression induced by TGF-β1, and promotes the expression of Smad7. TTR modulates the TGF-β1/Smad pathway to alleviate the generation of fibrotic tissue in response to IUA.