Hepatitis C Virus E2 Protein Induce Reactive Oxygen Species (ROS)-Related Fibrogenesis in the HSC-T6 Hepatic Stellate Cell Line

Chronic infection of hepatitis C virus (HCV) leads to hepatic fibrosis and subsequently cirrhosis, although the underlying mechanisms have not been established. Previous studies have indicated that the binding of HCV E2 protein and CD81 on the surface of hepatic stellate cells (HSCs) lead to the increased protein level and activity of matrix metallopeptidase (MMP) 2, indicating that E2 may involve in the HCV-induced fibrosis. This study was designed to investigate the involvement of HCV E2 protein in the hepatic fibrogenesis. Results showed that E2 protein may promote the expression levels of alpha-smooth muscle actin (alpha-SMA) and collagen alpha(I). Furthermore, several pro-fibrosis or pro-inflammatory cytokines, including transforming growth factor (TGF)-beta 1, connective tissue growth factor (CTGF), interleukin (IL)-6 and IL-1 beta, were significantly increased in E2 transfected-HSC cell lines, while the expression of MMP-2 are also considerably increased. Moreover, the significant increases of CTGF and TGF-beta 1 in a stable E2-expressing Huh7 cell line were also observed the same results. Further molecular studies indicated that the impact of E2 protein on collagen production related to higher production of ROS and activated Janus kinase (JAK) 1, JAK2 and also enhance the activation of ERK1/2 and p38, while catalase and inhibitors specific for JAK, ERK1/2, and p38 abolish E2-enhanced expression of collagen alpha(I). Taken together, this study indicated that E2 protein involve in the pathogenesis of HCV-mediated fibrosis via an up-regulation of collagen alpha(I) and oxidative stress, which is JAK pathway related. J. Cell. Biochem. 112: 233-243, 2011. (C) 2010 Wiley-Liss, Inc.