Transforming growth factor-β (TGF-β) has been implicated in the process of hepatic fibrosis, and stimulates production of extracellular matrix in hepatic stellate cells, which play a major role in the process. It has been recently reported that blockage of TGF-β signaling prevents hepatic fibrosis. We evaluated a strategy for anti-TGF-β gene therapy for hepatic fibrosis by transfecting plasmids expressing an entire extracellular domain of human TGF-β type II [soluble type II TGF-β receptor (sTGF-βIIR)] into skeletal muscle in a rat experimental model of dimethylnitrosamine- (DMN-) induced fibrosis. sTGF-βIIR treatment decreased significantly the occurrence of DMN-induced hepatic fibrosis, evaluated by computed image analysis and by measurement of hydroxyproline content of the liver, and reduced the expression of collagen and α-smooth muscle actin. The treatment also caused a significant decrease in hepatic levels of interleukin- (IL-) 12 (Th1 cytokine) and an increase in those of IL-10 (Th2 cytokine), indicating a change in the Th1/Th2 cytokine balance in the liver. In conclusion, blockade of TGF-β after intramuscular transfer of the soluble type II TGF-β receptor gene suppressed hepatic fibrosis, suggesting that this strategy may be useful for gene therapy of hepatic fibrosis.

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