Salvianolic acid B reverses the epithelial-to-mesenchymal transition of HK-2 cells that is induced by transforming growth factor-β

Salvianolic acid B (Sal B) is the most abundant bioactive molecule from Radix Salviae Miltiorrhizae , and has recently been used for treating renal fibrosis in traditional Chinese medicine. Here we investigated the ability reversal of Sal B to reverse the transdifferentiation of human kidney proximal tubular epithelial cells that was induced by transforming growth factor-beta 1 (TGF-β1). The effects of Sal B on HK-2 cell morphology were observed by phase contrast microscopy, while alpha smooth muscle actin and E-cadherin were studied by immunocytochemistry and real-time reverse transcription polymerase chain reaction, respectively. Exposure of HK-2 cells to TGF-β1 for 72 h induced a complete conversion of the epithelial cells to myofibroblasts. When HK-2 cells were co-incubated with Sal B and TGF-β1 for a further 72 h, the morphology of myofibroblasts returned to that of proximal tubular epithelial cells, whereas the myofibroblast phenotype was maintained after exposure of cells to TGF-β1 for 144 h. Sal B reduced alpha smooth muscle actin levels and increased E-cadherin levels compared with their epithelial-to-mesenchymal transition controls. The reversal effect of Sal B was dose-dependent. That Sal B reverses the epithelial-to-mesenchymal transition in vitro suggests that it could possibly facilitate the repair of tubular epithelial structures and the regression of renal fibrosis in injured kidneys.