Cholestasis-induced fibrosis is reduced by interferon α-2a and is associated with elevated liver metalloprotease activity

Background/Aim: Several drugs have been tested for the treatment of hepatic cirrhosis induced by various etiologic agents. Although interferon (IFN)α-2a has mostly been used to treat viral hepatitis, its antifibrogenic properties remain to be established. Methods: An experimental model of cholestasis-induced cirrhosis was used to test the effect of IFNα-2a. Cirrhosis was induced in rats via ligation of the common bile duct. IFNα-2a (100 000 IU/rat, s.c.) was administered daily throughout the experiment. Collagens and TIMP-1 mRNA transcripts were determined by semi-quantitative reverse transcriptase-polymerase chain reaction in liver tissue samples. Activity of metalloproteases (MMPs) was measured using gelatin (denatured collagen) as substrate and the specific size of the enzymes was estimated by zymograms. Histology was performed using Sirius red as a specific stain for collagenous material, and computerassisted morphometric analyses were carried out. A polyclonal mouse anti-plasminogen activator inhibitor (PAI-1) antibody was used to evaluate the distribution during treatment with IFNα-2a. Results/Conclusions: MMP-activity was up-regulated in bile duct ligated rats treated with IFNα-2a. MMP-activity in homogenates of total liver was minimal as compared with activity in non-parenchymal cells isolated from the same parental perfused liver, indicating a cryptic MMP activity which was completely abolished by EDTA and 1,10 phenanthroline. Three bands of gelatin degradation were detected by zymography, corresponding to 95, 75 and 65 kDa. IFNα-2a decreased PAI-1 immunoreactivity in liver tissue slices as well as biochemical activity in non-parenchymal cell extracts (3.3±0.08 vs 7.4±1.1 U/mg protein). Procollagen α1 (III) and α1 (IV) genes expression were also down-regulated 1.5 and 4-fold, respectively. Interestingly, TIMP-1 gene expression did not change. Functional hepatic tests: alanine aminotransferase, aspartate aminotransferase, bilirubins and alkaline phosphatase were significantly lower in IFNα-2a treated animals. Analysis of histology demonstrated that IFNα-2a promoted resolution of fibrosis and decreased bile duct proliferation.