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.