Nrf2 and Snail-1 in the prevention of experimental liver fibrosis by caffeine

摘要

AIM:To determine the molecular mechanisms involved in experimental hepatic fibrosis prevention by caffeine(CFA).METHODS:Liver fibrosis was induced in Wistar rats by intraperitoneal thioacetamide or bile duct ligation and they were concomitantly treated with CFA(15 mg/kg per day).Fibrosis and inflammatory cell infiltrate were evaluated and classified by Knodell index.Inflammatory infiltrate was quantified by immunohistochemistry(anti-CD11b).Gene expression was analyzed by quantitative reverse transcription-polymerase chain reaction for collagenⅠ?(Col-1),connective tissue growth factor(CTGF),transforming growth factorβ1(TGF-β1),tumor necrosis factor alpha(TNF-α),interleukin-1(IL-1),IL-6,superoxide dismutase(SOD)and catalase(CAT).Activation of Nrf2 and Snail-1 was analyzed by Westernblot.TNF-αexpression was proved by enzyme-linked immunosorbant assay,CAT activity was performed by zymography.RESULTS:CFA treatment diminished fibrosis index in treated animals.The Knodell index showed both lower fibrosis and necroinflammation.Expression of profibrogenic genes CTGF,Col-1 and TGF-β1 and proinflammatory genes TNF-α,IL-6 and IL-1 was substantially diminished with CFA treatment with less CD11b positive areas.Significantly lower values of transcriptional factor Snail-1 were detected in CFA treated rats compared with cirrhotic rats without treatment;in contrast Nrf2was increased in the presence of CFA.Expression of SOD and CAT was greater in animals treated with CFA showing a strong correlation between mRNA expression and enzyme activity.CONCLUSION:Our results suggest that CFA inhibits the transcriptional factor Snail-1,down-regulating profibrogenic genes,and activates Nrf2 inducing antioxidant enzymes system,preventing inflammation and fibrosis.