Autoantibodies against cytochromes P-4502E1 and P-4503A in alcoholics

Autoantibodies against soluble liver enzymes have been reported among alcoh olics, but the targets of self-reactivity toward membrane proteins of the l iver have not been characterized. Previously, among alcoholics, we found an tibodies against ethanol-derived radical protein adducts that are dependent on cytochrome P-4502E1 (CYP2E1) for their formation. To further investigat e autoantibodies against cytochrome P-450s during alcohol abuse, sera of ra ts chronically treated with ethanol in the total enteral nutrition model an d sera from alcoholics with or without alcohol liver disease and from contr ol subjects were analyzed by enzyme-linked immunosorbent assay and Western blotting for the presence of IgG against rat and human CYP2E1, rat CYP3A1, and human CYP3A4. A time-dependent appearance of IgG against rat CYP3A1 and CYP2E1 was evident during chronic ethanol feeding of rats. Anti-CYP2E1 rea ctivity showed positive correlation with the levels of hepatic CYP2E1 and w as inhibited by the CYP2E1 transcriptional inhibitor chlormethiazole. Scree ning of the human sera by enzyme-linked immunosorbent assay revealed reacti vity against CYP3A4 and CYP2E1 in about 20 to 30% and 10 to 20% of the alco holic sera, respectively. No difference were noted between sera from alcoho lics with or without hepatitis C virus infection, and only very little reac tivity was seen in sera from control subjects. Western blotting analysis re vealed anti-human CYP2E1 reactivity in 8 of 85 alcoholic sera and 3 of 58 c ontrol sera, whereas anti-CYP3A4 reactivity was detected in 18 of 85 alcoho lic sera and 4 of 58 control sera, which were different from the sera react ive with CYP2E1. Immunoblot reactivity of CYP3A4-positive alcoholic sera wa s found against glutathione-S-transferase fusion proteins containing trunca ted forms of CYP3A4, and such sera were also able to immunoprecipitate in v itro translated CYP3A4. Seven of eight sera showed reactivity toward domain s C-terminal of position Ser281, and 1 of 8 sera recognized autoepitopes wi thin the region Thr207-Ser281, These findings indicate that alcoholics deve lop autoantibodies against CYP2EI and CYP3A4 that the CYP3A4 C-terminal dom ain is a target for the autoantibody reactions among a subset of alcoholics . The novel finding of CYP3A4 autoantibodies and their significant expressi on among alcoholics warrants further investigation. Attention should be giv en to immune toxicity associated with CYP3A4 autoantibodies and cases of al cohol abuse that are accompanied by exposure to drugs and substances that a re CYP3A substrates.