Antifibrotic effects of tetrandrine on hepatic stellate cells and rats with liver fibrosis

Anti-inflammation strategies are one of the proposed therapeutic approaches to hepatic fibrosis. Tetrandrine (C38H42O8N2, molecular weight: 622; Tet), an alkaloid isolated from the Chinese medicinal herb Stephania tetrandra, has been shown to exert anti-inflammatory activity in pulmonary diseases. The purpose of the present study was to investigate the in vitro and in vivo effects of Tet on hepatic fibrosis. A cell line of rat hepatic stellate cells (HSC-T6) was stimulated with transforming growth factor-beta 1 (TGF-beta 1) or tumor necrosis factor-alpha (TNF-alpha). The inhibitory effects of Tet on the nuclear factor kappa B (NF kappa B) signaling cascade and molecular markers including intercellular adhesion molecule-1 (ICAM-1) and alpha-smooth muscle actin (alpha-SMA) secretion were assessed. Fibrosis was induced by dimethylnitrosamine (DMN) administration in rats for 4 weeks. Fibrotic rats were randomly assigned to one of the four groups: vehicle (0.7% carboxyl methyl cellulose, CMC), Tet (1 mg/kg), Tet (5 mg/kg), or silymarin (50 mg/kg), each given by gavage twice daily for 3 weeks starting after 1 week of DMN administration. At the end of the study, liver tissues were scored for fibrosis and analyzed for molecular markers of fibrosis. Tetrandrine (0.5-5.0 mu mol/L) concentration-dependently inhibited NF kappa B transcriptional activity induced by TNF-alpha, including I kappa B alpha phosphorylation and mRNA expressions of ICAM-1 in HSC-T6 cells. In addition, Tet also inhibited TGF-beta 1-induced alpha-SMA secretion and collagen deposition in HSC-T6 cells. Fibrosis scores of livers from DMN-treated rats with high-dose Tet (1.3 +/- 0.3) were significantly reduced in comparison with DMN-treated rats receiving saline (2.0 +/- 0.2). Hepatic collagen content of DMN rats was significantly reduced by either Tet or silymarin treatment. Double-staining results showed that alpha-SMA- and NF kappa B-positive cells were decreased in the fibrotic livers by Tet and silymarin treatment. In addition, mRNA expression of ICAM-1, alpha-SMA, and TGF-beta 1 was attenuated by Tet treatment. Moreover, levels of plasma aspartate aminotransferase and alanine aminotransferase activities were reduced by Tet and silymarin treatment. Tetrandrine exerts antifibrotic effects in both HSC-T6 cells and in rats with DMN-induced fibrosis.