Effect of Angiotensin-converting Enzyme Inhibition on Experimental Hepatic Fibrogenesis

The renin-angiotensin system is suggested to be important in liver fibrogenesis. It induces hepatic stellate cell proliferation and up-regulates transforming growth factor beta-1 (TGF-β1) expression. Matrix metalloproteinase-2 (MMP-2) is involved in extracellular matrix remodelling. Fibrosis, a consequence of most chronic liver diseases, may be the result of a disturbed balance between fibrogenesis and fibrolysis. The aim of this study was to investigate the effect of enalapril on liver fibrogenesis induced in rats by bile-duct ligation. Forty-seven rats were divided into two groups: bile-duct ligated (BDL) (n = 24) and BDL + enalapril (n = 23). Fibrosis was evaluated by the Knodell scoring system, and TGF-β1 and MMP-2 were assessed with immunohistochemistry at the second, fourth and sixth weeks after bile-duct ligation. In the BDL group, TGF-β1 increased by the second week and this increase continued through weeks 4 and 6. In the BDL + enalapril group, TGF-β1 was significantly lower than the other group (P < 0.05). MMP-2 progressively decreased after week 2 in the BDL group. In the BDL + enalapril group, MMP-2 was significantly higher than the BDL group at the fourth and sixth weeks. These results suggest that enalapril reduces the liver tissue TGF-β1 and has an ameliorating effect on the fibrosis markers TGF-β1 and MMP-2.