Cytochromes P450 2A6, 2E1, and 3A and production of protein-aldehyde adducts in the liver of patients with alcoholic and non-alcoholic liver diseases.

BACKGROUND/AIMS: Interaction between CYP2E1, ethanol metabolites, and enhanced lipid peroxidation is linked to the pathogenesis of alcoholic liver disease. This study was conducted to compare the expression of various cytochrome enzymes and the appearance of aldehyde adducts in humans. METHODS: Acetaldehyde- and lipid peroxidation-derived protein adducts and CYP2A6, 2E1, and 3A4/5 were examined immunohistochemically from liver specimens of 12 alcohol abusers with either mild (n=7) or severe (n=5) liver disease, and from nine non-drinking patients with non-alcoholic steatosis (n=4), or hepatitis (n=5). RESULTS: Ethanol-inducible CYP2E1 was present in all alcoholic livers. While CYP2A6 in zone 3 hepatocytes was also abundant in the alcoholic patients with various degrees of liver disease, CYP3A415 was most prominent in alcoholic cirrhosis. The sites of CYP2E1 and CYP2A6 immunoreactivity co-localized with fatty deposits, and with the sites of acetaldehyde and lipid peroxidation-derived protein adducts. The CYP enzymes were also abundant in the centrilobular hepatocytes of patients with fatty liver due to obesity or diabetes. CONCLUSIONS: Alcohol-induced liver damage is associated with a generalized induction of CYP2A6, CYP2E1 and CYP3A4 and generation of acetaldehyde and lipid peroxidation-derived protein-aldehyde adducts. However, CYP induction also occurred in patients with non-alcoholic steatosis.

Autoimmune responses against oxidant stress and acetaldehyde-derived epitopes in human alcohol consumers.

BACKGROUND: Studies in experimental animals have indicated that chronic ethanol ingestion triggers the formation of antibodies directed against proteins modified with reactive metabolites of ethanol and products of lipid peroxidation. However, the nature and prevalence of such antibodies have not been compared previously in alcoholic patients. METHODS: Autoantibodies against adducts with acetaldehyde- (AA), malondialdehyde- (MDA), and oxidized epitopes (Ox) were examined from sera of 54 alcohol consumers with (n = 28) or without (n = 26) liver disease, and from 20 nondrinking controls. RESULTS: Anti-AA-adduct IgA and IgG antibodies were elevated in 64% and 31% of patients with biopsy-proven alcoholic liver disease (ALD, n = 28), respectively. The IgA titers were significantly higher than those from nondrinking controls (p < 0.001), or heavy drinkers without significant liver disease (p < 0.001). Anti-MDA adduct titers (IgG) were elevated in 70% of the ALD patients. These titers were significantly higher (p < 0.001) than those from nondrinking controls, or heavy drinkers without liver disease. Antibodies (IgG) against Ox epitopes occurred in 43% of ALD patients, and the titers also were significantly higher (p < 0.05) than those from nondrinking controls. The anti-AA and anti-MDA adduct titers in ALD patients correlated significantly with the combined clinical and laboratory index (CCLI) of liver disease severity (r(s) = 0.449, p < 0.05; r(s) = 0.566, p < 0.01, respectively), the highest prevalences of anti-AA-adducts (73%) and anti-MDA-adducts (76%) occurring in ALD patients with cirrhosis. CONCLUSIONS: The present results indicated that autoantibodies against several distinct types of protein modifications are generated in ALD patients showing an association with the severity of liver disease.

Serum IgA, IgG, and IgM antibodies directed against acetaldehyde-derived epitopes: relationship to liver disease severity and alcohol consumption.

Chronic ethanol ingestion has been suggested to trigger the formation of antibodies that recognize acetaldehyde-protein condensates. In this study, assays for immunoglobulin (Ig) A, IgG, and IgM antibodies to acetaldehyde-derived adducts were performed on sera of 140 alcohol consumers, 19 patients with nonalcoholic liver disease (NALD), 35 healthy nondrinking controls, and 10 nondrinking patients with IgA or IgG myeloma. Anti-acetaldehyde (Ach)-adduct antibodies of each Ig isotype were found from the alcohol abusers. In alcoholic liver disease (ALD, n = 86) IgA titers were elevated in 69% of the patients. These titers were significantly higher than those from patients with NALD (P < .001), nondrinking controls (P < .001), or heavy drinkers (n = 54) without any clinical and biochemical signs of liver disease (P < .001). In contrast, anti-adduct IgG titers were significantly elevated both in ALD and in heavy drinkers as compared with patients with NALD (P < .001) or nondrinking controls (P < .01 and P < .05, respectively). The anti-adduct immunoglobulin (Ig)A, IgG, and IgM titers in patients with alcoholic liver disease (ALD) correlated with the combined clinical and laboratory index of liver disease severity (r(s) = .497, P < .001; r(s) = .361, P < .01; and r(s) = .322, P < .01). Anti-adduct IgA titers also correlated with serum bilirubin (r = .768, P < .001) and interleukin 6 (r = .504, P < .001). Anti-adduct IgG titers were, in turn, found to correlate with the presence of inflammation (P < .01) and necrosis (P < .01). During follow-up studies of individual patients, parallel changes were observed in the anti-adduct IgG titers, disease severity, and serum markers of fibrogenesis. The present results provide evidence that antibodies representing distinct Ig classes directed against acetaldehyde (Ach)-derived adducts of proteins are formed in alcoholic patients showing an association with the severity of liver disease. The follow-up data also support an association between such immune responses and the aggravation of liver disease.

Induction of avidin messenger ribonucleic acid in the chick oviduct by progesterone and other steroids.

Avidin gene expression was analyzed using an avidin immunoassay and RNA hybridization analysis. To ascertain whether the induction of the avidin gene by progesterone remains specific also during secondary restimulation with diethylstilbestrol, chicks were given different steroid hormones or hormone combinations. Progesterone-specific induction of avidin protein and messenger RNA (mRNA) was 15- to 30-fold over the control even after secondary restimulation with diethylstilbestrol. A functional difference between the progesterone response element and glucocorticoid response element was suggested, since dexamethasone alone did not induce avidin in vivo. In spite of progesterone specificity, a combination of progesterone with other steroids nevertheless generated a synergistic increase in the amount of avidin mRNA. This may indicate that binding of progesterone receptor to the progesterone response element may be important to alter the functional activity of other hormone response elements present on the avidin gene. The time response curve of the avidin mRNA induction by progesterone was also determined. Avidin mRNA was detectable 8 h after progesterone induction, and its amount was maximal after 16-24 h. This would indicate that the avidin gene belongs in the so-called late responder genes, which also include chicken ovalbumin, ovomucoid, and lysozyme genes.