We investigated whether gene transfer of insulin-like growth factor I (IGF-I) to the hepatic tissue was able to improve liver histology and function in established liver cirrhosis. Rats with liver cirrhosis induced by carbon tetrachloride (CCl4) given orally for 8 weeks were injected through the hepatic artery with saline or with Simian virus 40 vectors encoding IGF-I (SVIGF-I), or luciferase (SVLuc). Animals were sacrificed 8 weeks after vector injection. In cirrhotic rats we observed that, whereas IGF-I was synthesized by hepatocytes, IGF-I receptor was predominantly expressed by nonparenchymal cells, mainly in fibrous septa surrounding hepatic nodules. Rats treated with SVIGF-I showed increased hepatic levels of IGF-I, improved liver function tests, and reduced fibrosis in association with diminished ¿-smooth muscle actin expression, up-regulation of matrix metalloproteases (MMPs) and decreased expression of the tissue inhibitors of MMPs TIM-1 and TIM-2. SVIGF-I therapy induced down-regulation of the profibrogenic molecules transforming growth factor beta (TGFß), amphiregulin, platelet-derived growth factor (PDGF), connective tissue growth factor (CTGF), and vascular endothelium growth factor (VEGF) and induction of the antifibrogenic and cytoprotective hepatocyte growth factor (HGF). Furthermore, SVIGF-I-treated animals showed decreased expression of Wilms tumor-1 (WT-1; a nuclear factor involved in hepatocyte dedifferentiation) and up-regulation of hepatocyte nuclear factor 4 alpha (HNF4¿) (which stimulates hepatocellular differentiation). The therapeutic potential of SVIGF-I was also tested in rats with thioacetamide-induced liver cirrhosis. Also in this model, SVIGF-I improved liver function and reduced liver fibrosis in association with up-regulation of HGF and MMPs and down-regulation of tissue inhibitor of metalloproteinase 1 (TIMP-1). Conclusion: IGF-I gene transfer to cirrhotic livers induces MMPs and hepatoprotective factors leading to reversion of fibrosis and improvement of liver function. IGF-I gene therapy may be a useful alternative therapy for patients with advanced cirrhosis without timely access to liver transplantation.

Background: Inflammation and fibrogenesis are directly related to chronic liver disease progression, including hepatocellular carcinoma (HCC) development. Currently there are few therapeutic options available to inhibit liver fibrosis. We have evaluated the hepatoprotective and anti-fibrotic potential of orally-administered 59-methylthioadenosine (MTA) in Mdr2(-/-) mice, a clinically relevant model of sclerosing cholangitis and spontaneous biliary fibrosis, followed at later stages by HCC development. Methodology: MTA was administered daily by gavage to wild type and Mdr2(-/-) mice for three weeks. MTA anti-inflammatory and anti-fibrotic effects and potential mechanisms of action were examined in the liver of Mdr2(-/-) mice with ongoing fibrogenesis and in cultured liver fibrogenic cells (myofibroblasts). Principal Findings: MTA treatment reduced hepatomegaly and liver injury. alpha-Smooth muscle actin immunoreactivity and collagen deposition were also significantly decreased. Inflammatory infiltrate, the expression of the cytokines IL6 and Mcp-1, pro-fibrogenic factors like TGF beta 2 and tenascin-C, as well as pro-fibrogenic intracellular signalling pathways were reduced by MTA in vivo. MTA inhibited the activation and proliferation of isolated myofibroblasts and down-regulated cyclin D1 gene expression at the transcriptional level. The expression of JunD, a key transcription factor in liver fibrogenesis, was also reduced by MTA in activated myofibroblasts. Conclusions/Significance: Oral MTA administration was well tolerated and proved its efficacy in reducing liver inflammation and fibrosis. MTA may have multiple molecular and cellular targets. These include the inhibition of inflammatory and profibrogenic cytokines, as well as the attenuation of myofibroblast activation and proliferation. Downregulation of JunD and cyclin D1 expression in myofibroblasts may be important regarding the mechanism of action of MTA. This compound could be a good candidate to be tested for the treatment of (biliary) liver fibrosis.