Role of cytochrome P4502E1-dependent formation of hydroxyethyl free radical in the development of liver damage in rats intragastrically fed with ethanol

Abstract

In recent years the possible involvement of free radicreased the trapping of hydroxyethyl free radicals in cal mediated oxidative injury in the pathogenesis of liver microsomes incubated in vitro with ethanol. Fur-alcohol-induced liver diseases has received increasing thermore, these inhibitors also greatly reduced the pro-attention.1 Clinical studies have shown that products duction of hydroxyethyl radical-derived epitopes detect-of lipid peroxidation can be detected in the liver and associated with an increase of lipid peroxidation, which Rats fed intragastrically with ethanol developed antiwas detectable both in vitro and in vivo. 6,7 Moreover, bodies reacting with hydroxyethyl radicals-modified proteins and the formation of these antibodies was the treatment of rats with diallyl sulfide (DAS) or phegreatly reduced by DAS and PIC. Taken together these nylethyl isothiocyanate (PIC), which inhibited CYP2E1 results suggest that CYP2E1 plays an important role in expression, strongly decreased lipid peroxidation meathe generation of hydroxyethyl radicals during chronic sured in vitro in liver microsomes as well as in vivo in the plasma of alcohol-fed animals. 10 Interestingly, among these animals a positive correlation was evident Abbreviations: CYP2E1, cytochrome P450 2E1; DAS, diallyl sulfide; PIC, between the histological evidence of liver injury (i.e., phenylethyl isothiocyanate; KLH, keyhole limpet hemocyanin; RSA, rat serum steatosis, inflammation, and necrosis) and the liver albumin; Ig, immunoglobulin; 4-POBN, 4-pyridyl-1-oxide-t-butyl nitrone; CYP2E1 content. bind to microsomal proteins 13 and that these adducts Received April 12, 1995; accepted August 17, 1995. have immunologic properties leading to the production

Production of a cytochrome P450 2E1 transgenic mouse and initial evaluation of alcoholic liver damage

“…Antibodies against hydroxyethyl-CYP2E1 adducts are found in the serum of humans and in animals after administration of ethanol. [3][4][5] The highest concentration of CYP2E1 is found in perivenular hepatocytes, the first area of the liver to be damaged by alcohol. 6,7 Hepatic CYP2E1 enzyme activity is significantly higher in alcoholic patients with liver disease than in alcoholic patients without signs of liver disease.…”

Detection of circulating antibodies against malondialdehyde-acetaldehyde adducts in patients with alcohol-induced liver disease

“…[5][6][7][8][9][10]12,28,29 Although the individual levels of anti-MAA IgG positively correlated with those of IgG recognizing acetaldehyde, and MDA-derived adducts, competition experiments show that the reactivity with MAAderived epitopes is largely independent from that directed against acetaldehyde and MDA-derived antigens. This latter observation is of particular interest, because protein derivatization with high concentrations of MDA leads to the formation of substantial amounts of cyclic MAA adducts.…”

“…11 Circulating antibodies recognizing liver proteins alkylated by hydroxyethyl-free radicals have also been detected in rats chronically fed ethanol as well as in patients with alcohol-induced cirrhosis. 12,13 These antibodies might be relevant for the development of liver damage, because they are specific for ALD 13 and able to trigger immune-mediated cell killing by recognizing specific epitopes on ethanol-treated hepatocytes. 14 Recent studies from our laboratory have shown that malonildialdehyde (MDA), a product of ethanol-induced lipid peroxidation, and acetaldehyde react together with proteins to form mixed malonildialdehyde-acetaldehyde (MAA) adducts.…”

CYP2E1 and oxidative liver injury by alcohol

“…Experimentally, a decrease in CYP2E1 induction was found to be associated with a reduction in alcohol-induced liver injury (121,122). CYP2E1 inhibitors such as diallyl sulfide (DAS) (123), phenethyl isothiocyanate (PIC) (124,125) and chlormethiazole (126), blocked the lipid peroxidation and ameliorated the pathologic changes in ethanol-fed rats. Polyenylphosphatidylcholine (PPC), another compound exerting anti-CYP2E1 properties (127) was effective in opposing alcohol-induced oxidative stress (40).…”