Adenoviral expression of a transforming growth factor-β1 antisense mRNA is effective in preventing liver fibrosis in bile-duct ligated rats

BACKGROUND: Transforming growth factor-beta (TGF-beta) is a key mediator in establishing liver fibrosis. Therefore, TGF-beta as a causative agent may serve as a primary target for antifibrotic gene therapy approaches. We have previously shown that the adenoviral delivery of a transgene constitutively expressing a TGF-beta1 antisense mRNA blocks TGF-beta synthesis in culture-activated hepatic stellate cells and effectively abolishes ongoing fibrogenesis in vitro. METHODS: Ligature of the common bile duct was used to induce liver fibrosis in rats. The effect of the TGF-beta1 antisense on fibrogenesis was analyzed in this model of liver injury. RESULTS: In the present study, we demonstrate that the adenoviral vector directs the synthesis of mRNA quantities that are approximately 8000-fold more abundant than endogenous TGF-beta1 mRNA. In experimentally injured rat livers induced by ligature of the common bile duct, a model for persistent fibrogenesis and cirrhosis, administration of the adenoviral vector abrogates TGF-beta-enhanced production of collagen and alpha-smooth muscle actin. Furthermore, the number of cells positive for alpha-smooth muscle actin resulting from active recruitment of activated hepatic stellate cells around the bile ductular structures was significantly reduced in animals after application of Ad5-CMV-AS-TGF-beta1. However, the observed elevated serum levels of aspartate aminotransferase, alanine aminotransferase, and bilirubin induced in this obstructive liver injury model were not significantly altered in the presence of the TGF-beta antagonist. CONCLUSION: Taken together, our data provides in vivo evidence that the delivery of TGF-beta1 antisense mRNA specifically abolishes the diverse effects of direct TGF-beta function in ongoing liver fibrogenesis. Therefore, we conclude that the expressed transgene is therapeutically useful for inhibition of TGF-beta effects in diverse applications, ranging from clarification of TGF-beta function in the course of liver injury to the development of novel gene therapeutic approaches.