ZONATED EXPRESSION OF CYTOKINES IN RAT-LIVER - EFFECT OF CHRONIC ETHANOL AND THE CYTOCHROME-P450 2E1 INHIBITOR, CHLORMETHIAZOLE

The release of proinflammatory cytokines by endotoxins and during oxid ative stress is considered to be an early key step in the pathogenesis of alcoholic liver disease (ALD). Ethanol-inducible cytochrome P450 2 E1 (CYP2E1) has potentially pro-oxidative and toxicological properties , and its expression is restricted to the perivenous region of liver, We investigated zonal differences of cytokine expression in rat liver and how these are affected by alcohol exposure and by chlormethiazole (CMZ), a transcriptional and posttranslational inhibitor of hepatic CY P2E1. Periportal and perivenous cell lysates were obtained by the digi tonin pulse technique from livers of rats treated with ethanol and CMZ for 38 days. Cytokine expression on the mRNA and protein levels was q uantified using competitive polymerase chain reaction (PCR) and Wester n blot, respectively. Chronic ethanol treatment significantly increase d the expression of CYP2E1, microsomal p-nitrophenol hydroxylase activ ity (indicative for CYP2E1 enzyme activity), and the expression of tra nsforming growth factor beta(1) (TGF-beta(1)), tumor necrosis factor a lpha (TNF-alpha), and interleukin (IL)-1 beta (1,4- to 4.6-fold). In c ontrast, ethanol caused a decrease in IL-4 expression and had no influ ence on IL-6 expression. CMZ treatment caused a reduction in hepatic C YP2E1 expression and in the ethanol-induced cytokine expression by 40% to 60%. Expression of IL-6, IL-2, and IL-4 mRNA occurred preferential ly in the periportal region, whereas ethanol caused a pronounced incre ase in the perivenous expression of TGF-beta(1), which was inhibited b y CMZ as monitored both on the mRNA and protein levels. These results show the zonated expression of several cytokines and the counteraction of CMZ on all effects of ethanol on cytokine expression. The data fur ther strengthen a link between increased CYP2E1 expression and enhance d cytokine expression as important events in the development of ALD.