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Background & Aims: Circulating auto-antibodies targeting conformational antigens on cytochrome P4502E1 (CYP2E1) are detectable in patients with chronic hepatitis C (CHC) and are associated with more severe necro-inflammation. This study investigated the antigen specificity and the possible origin of these auto-antibodies., Methods: CYP2E1 site-directed mutagenesis and molecular simulation were used to characterize the epitope specificity of CHC-associated anti-CYP2E1 auto-antibodies., Results: Immunoprecipitation experiments using differently mutated human CYP2E1s revealed that conformational anti-CYP2E1 antibodies targeted two epitopes located on the molecule surface in an area between Lys(324)-Glu(346) at J-K'' helices overlapping. Such epitopes were not recognized by the sera targeting linear CYP2E1 antigens. The CYP2E1(324-346) peptide showed good homology with two sequences (NS5b(438-449) and NS5b(456-465)) within the NS5b protein of hepatitis C virus (HCV). Consistently, conformational anti-CYP2E1 IgG bind to GST-conjugated NS5b(438-449) and NS5b(456-465) more efficiently than those recognizing CYP2E1 linear antigens. Competition experiments confirmed the cross-reactivity of conformational anti-CYP2E1 IgG with both NS5b(438-449) and NS5b(456-465). Moreover, mice immunized with GST-conjugated NS5b(438-449) or NS5b(456-465) peptides developed antibodies recognizing human CYP2E1., Conclusions: In CHC patients cross-reactivity between CYP2E1 and specific sequences in HCV-NS5b protein can promote the development of auto-antibodies targeting conformational epitopes on the CYP2E1 surface that might contribute to hepatic injury., (Copyright 2010 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

Background/aims: The contribution of oxidative stress to the pathogenesis of chronic hepatitis C (CHC) is still poorly elucidated. This study investigated the relationship between oxidative stress, insulin resistance, steatosis and fibrosis in CHC., Methods: IgG against malondialdehyde-albumin adducts and HOMA-IR were measured as markers of oxidative stress and insulin resistance, respectively, in 107 consecutive CHC patients., Results: Oxidative stress was present in 61% of the patients, irrespective of age, gender, viral load, BMI, aminotransferase level, histology activity index (HAI) and HCV genotype. Insulin resistance and steatosis were evident in 80% and 70% of the patients, respectively. In the patients infected by HCV genotype non-3, but not in those with genotype 3 infection HOMA-IR (p<0.03), steatosis (p=0.02) and fibrosis (p<0.05) were higher in the subjects with oxidative stress than in those without. Multiple regression analysis revealed that, HOMA-IR (p<0.01), fibrosis (p<0.01) and oxidative stress (p<0.05) were independently associated with steatosis, whereas steatosis was independently associated with oxidative stress (p<0.03) and HOMA-IR (p<0.02). Steatosis (p<0.02) and HAI (p=0.007) were also independent predictors of fibrosis., Conclusions: In patients infected by HCV genotype non-3, oxidative stress and insulin resistance contribute to steatosis, which in turn exacerbates both insulin resistance and oxidative stress and accelerates the progression of fibrosis.

Background/aims: Chronic hepatitis C (CHC) is often associated with auto-immune reactions. In the light of the role of alcohol in promoting CHC progression, we have investigated the possible presence of auto-reactivity against the ethanol-inducible cytochrome P4502E1 (CYP2E1) in CHC patients with and without alcohol consumption., Methods: The IgG reactivity against recombinant human CYP2E1 was evaluated by solid-phase immunoassays in 102 CHC patients with different alcohol consumption and 59 HCV-free controls., Results: Auto-antibodies against CYP2E1 were significantly (p<0.0001) increased in CHC patients as compared to controls. Anti-CYP2E1 IgG above the 97th percentile in the controls were evident in 41 (40%) CHC patients. Competition experiments revealed that CYP2E1 recognition was not due to the cross-reactivity with CYP2D6. The detection of anti-CYP2E1 IgG was unrelated to alcohol consumption and no difference in gender, age, aminotransferase levels and virus genotype was evident among the patients with or without anti-CYP2E1 auto-antibodies. However, anti-CYP2E1 auto-reactivity was significantly (p=0.025) associated with the severity of periportal/periseptal interface hepatitis. Moreover, confocal microscopy demonstrated that anti-CYP2E1 IgG associated with CHC recognized CYP2E1 exposed on the outer side of hepatocyte plasma membranes., Conclusions: HCV infection favours the breaking of self-tolerance against CYP2E1 that might contribute to hepatocyte injury.

Background/aims: Circulating anti-phospholipid antibodies (aPL) are often present in patients with alcoholic liver disease (ALD). The observations that defects in the disposal of apoptotic corpses leads to the development of aPL prompted us to investigate whether ALD-associated aPL might recognize antigens in apoptotic cells., Methods: Apoptosis was induced in HuT-78 human T-lymphoma and HepG2 hepatoma cells by, respectively, FAS ligation with CH11 monoclonal antibodies or the incubation with ethanol (400 mmol/L)., Results: Flow cytometry revealed that IgG from ALD patients with high aPL titers selectively bind to the surface of apoptotic, but not to viable cells. No binding was instead evident using either control or aPL-negative ALD sera. ELISA assays using different oxidized phospholipids as antigens showed that anti-phospholipid reactivity of ALD sera was mainly directed towards oxidized cardiolipin and phosphatidylserine. The pre-adsorption of aPL-positive sera with oxidized phosphatidylserine, but not with oxidized cardiolipin, lowered aPL binding to apoptotic HuT-78 cells by about 50%. No effect was instead observed by pre-adsorption with oxidation-protected phospholipids or with human serum albumin adducted with different lipid peroxidation products., Conclusions: aPL associated with ALD target apoptotic cells by specifically recognizing oxidized phosphatidylserine, suggesting a possible link between hepatocyte apoptosis and anti-phospholipid auto-reactivity in ALD.