Gypenosides Ameliorate Carbon Tetrachloride-Induced Liver Fibrosis by Inhibiting the Differentiation of Hepatic Progenitor Cells into Myofibroblasts

Gypenosides (GPs), the predominant components of Gynostemma pentaphyllum, exert antifibrotic effects; however, the mechanisms underlying their ability to ameliorate liver fibrosis are unclear. Liver fibrosis was induced in C57BL/6 mice via subcutaneous injection of 10% carbon tetrachloride (CCl4 three times a week for two weeks. Then, CCl4 was administered in conjunction with intragastric GPs for another three weeks. For in vitro analyses, WB-F344, hepatatic progenitor cells (HPCs) were treated with transforming growth factor beta 1 (TGF-beta 1) with or without GPs for 48 h. The results showed that alanine aminotransferase (ALT) and aspartate transaminase (AST) activity, deposition of collagen, hydroxyproline content, and expression of alpha-smooth muscle actin (alpha-SMA) and collagen type I (Col I) were significantly decreased after treatment with GPs (p < 0: 01, p < 0: 05, p < 0: 05, p < 0: 05). In the 5M CCl4 group, the expression of HPC markers, Sox9 and cytokeratin 19 (CK19), was significantly increased compared with the normal or GPs-treated group (p < 0: 05, p < 0: 01). Immunostaining showed that the number of Sox9 and alpha-SMA double-positive cells was higher in the 5M CCl4 group than in the normal group, but the addition of GPs caused this cell number to decrease. In WB-F344 cells, the expression of alpha-SMA and Col I was significantly increased after treatment with TGF-beta 1, whereas in the GPs treatment group, expression was markedly decreased (p < 0: 05). The levels of TGF-beta 1 and TGF-beta R1 were markedly reduced after GPs treatment both in vivo and in vitro. In conclusion, GPs ameliorated CCl4-induced liver fibrosis via the inhibition of TGF-beta signaling, consequently inhibiting the differentiation of HPCs into myofibroblasts.