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

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.

Rosmarinic acid attenuates hepatic fibrogenesis via suppression of hepatic stellate cell activation/proliferation and induction of apoptosis

Objective:To investigate the antifibrotic role of rosmarinic acid(RA),a natural polyphenolic compound,on HSCs activation/proliferation and apoptosis in vitro and in vivo. Methods:The impact of RA on stellate cell line(HSC-T6) proliferation,activation and apoptosis was assessed along with its safety on primary hepatocytes. In vivo,rats were divided into:(i) normal;(ii) thioacetamide(TAA)-intoxicated rats for 12 weeks;(iii) TAA+silymarin or(iv) TAA+RA. At the end of experiment,liver functions,oxidative stress,inflammatory and profibrogenic markers,tissue inhibitor metalloproteinases type-1(TIMP-1) and hydroxyproline(HP) levels were evaluated. Additionally,liver histopathology and immunohistochemical examinations of alpha-smooth muscle actin(α-SMA),caspase-3 and proliferation cellular nuclear antigen(PCNA) were determined. Results:RA exhibited anti-proliferative effects on cultured HSCs in a time and concentration dependent manner showing an IC50 of 276 μg/mL and 171 μg/mL for 24 h and 48 h,respectively,with morphological reversion of activated stellate cell morphology to quiescent form. It significantly improved ALT,AST,oxidative stress markers and reduced TIMP-1,HP levels,inflammatory markers and fibrosis score(S1 vs S4). Furthermore,reduction in α-SMA plus elevation in caspase-3 expressions of HSCs in vitro and in vivo associated with an inhibition in proliferation of damaged hepatocytes were recorded. Conclusions:RA impeded the progression of liver fibrosis through inhibition of HSCs activation/proliferation and induction of apoptosis with preservation of hepatic architecture.