Effect of the selective Cyclooxygenase-2 Inhibition by HNHA [ N-hydroxy-7-(2-naphthylthio) heptanomide]on liver fibrosis in the bile duct ligated rat

Abstract

[한글]

[영문]Cholestasis provides the initial step to trigger the fibrogenic process in biliary fibrosis. COX-2 has been known to be upregulated in various chronic liver diseases such as virus or toxin-induced injury. Here, I report a new synthetic small molecule, N-hydroxy-7-(2-naphthylthio) heptanomide (HNHA), as a COX-2 inhibitor with anti-hepatic damage in vivo. I hypothesized that selective COX-2 inhibition by HNHA and SAHA (Suberoylanilide hydroxamic acid) could suppress COX-2 associated hepatic inflammation and fibrogenesis in the cholestatic liver. Ninety Sprague-Dawley rats were assigned into five groups, received experimental treatments. Group A (n=10) were sham-operated rats. Group B (n=20) received bile duct ligation (BDL). Group C (n=20) received BDL and daily injection of selective COX-2 inhibitor (meloxicam, 1.6mg/kg/day). Group D (n=20) received BDL and daily injection of selective COX-2 inhibitor (HNHA 0.8mM/kg/day). Group E (n=20) received BDL and daily injection of selective COX-2 inhibitor (SAHA 0.8 mM/kg/day). Expressions of α-SMA, TGF-β1, COX-2 and collagen were evaluated by immunohistochemical staining. Western blot analysis was used to determine the expression of TGF-β1, COX-2, MMP-2 enzyme linked immunosorbent assay (ELISA) for TGF-β1 was also performed. After BDL for 3 weeks, COX-2 expression was strongly confined to bile duct epithelium and less in hepatocytes. Non-parenchymal cell did not express COX-2. TGF-β1 was stained mainly around the proliferating bile ductules and zone 1 hepatocytes. Quantitative analysis of the liver fibrotic lesions showed that HNHA suppressed liver fibrosis stronger than meloxicam. Liver from group C, D and E showed weak or no staining of α-SMA, TGF-β1, COX-2 and collagen. Western blot analysis and ELISA showed that HNHA suppresses the expression of hepatic COX-2, MMP-9 and TGF-β1. In conclusion, BDL induces COX-2 expression and HNHA selectively suppresses COX-2 expression, suggesting that it could be a potential agent for treating hepatic fibrosis in cholestasis.