Adenovirus-mediated transfer of siRNA against PAI-1 mRNA ameliorates hepatic fibrosis in rats

Background/Aims Plasminogen activator inhibitor-1 (PAI-1) is a potential profibrotic molecule. The aim of this study was to evaluate the therapeutic effect of PAI-1 small interfering RNA (siRNA) on experimental hepatic fibrosis and investigate the intrinsic mechanisms. Methods Hepatic fibrosis in rats was induced by dimethylnitrosamine (DMN) administration or bile duct ligation (BDL). An adenovirus carrying PAI-1 shRNA (AdshPAI) was generated and administered via tail vein injection. The expression of PAI-1 was confirmed by real-time RT-PCR and immunohistochemistry. The effect of AdshPAI on fibrosis was evaluated by histological and immunohistochemical examination. Results We found that PAI-1 was downregulated after AdshPAI administration. Liver fibrosis was significantly improved after AdshPAI administration in both DMN and BDL models. AdshPAI treatment facilitated matrix degradation by correcting the levels of matrix metalloproteinases (MMPs) and its inhibitors (TIMPs) through upregulation of MMP9, MMP13 and downregulation of TIMP-1. Moreover, AdshPAI treatment stimulated hepatocellular proliferation and inhibited cellular apoptosis. Conclusions This study suggests that AdshPAI treatment has a protective effect on hepatocytes and ameliorates liver fibrogenesis. Inhibiting the upregulation of PAI-1 during liver fibrosis may be an antifibrotic pathway worth exploiting. Plasminogen activator inhibitor-1 (PAI-1) is a potential profibrotic molecule. The aim of this study was to evaluate the therapeutic effect of PAI-1 small interfering RNA (siRNA) on experimental hepatic fibrosis and investigate the intrinsic mechanisms. Hepatic fibrosis in rats was induced by dimethylnitrosamine (DMN) administration or bile duct ligation (BDL). An adenovirus carrying PAI-1 shRNA (AdshPAI) was generated and administered via tail vein injection. The expression of PAI-1 was confirmed by real-time RT-PCR and immunohistochemistry. The effect of AdshPAI on fibrosis was evaluated by histological and immunohistochemical examination. We found that PAI-1 was downregulated after AdshPAI administration. Liver fibrosis was significantly improved after AdshPAI administration in both DMN and BDL models. AdshPAI treatment facilitated matrix degradation by correcting the levels of matrix metalloproteinases (MMPs) and its inhibitors (TIMPs) through upregulation of MMP9, MMP13 and downregulation of TIMP-1. Moreover, AdshPAI treatment stimulated hepatocellular proliferation and inhibited cellular apoptosis. This study suggests that AdshPAI treatment has a protective effect on hepatocytes and ameliorates liver fibrogenesis. Inhibiting the upregulation of PAI-1 during liver fibrosis may be an antifibrotic pathway worth exploiting.