We have previously shown a relationship between plasma endotoxin levels and severity of alcoholic liver injury in the intragastric feeding rat model. We attempted to reduce both circulating endotoxin and liver injury in this model by administering a lactobacillus strain (species GG) which survives for prolonged periods in the gastrointestinal tract. Male Wistar rats were fed ethanol and liquid diet containing corn oil (CO+E). Another group of animals (CO+E+L) received the diet containing ethanol plus a daily bolus of lactobacilli GG concentrate (10(10) CFU). All animals were sacrificed after one month. All animals had plasma endotoxin measurements and evaluation of severity of pathologic changes in the liver. The weight gain and blood alcohol levels were similar in both groups. The mean +/- SE of the pathology score was significantly higher (3.4 +/- 0.85) in the CO+E group compared to the CO+E+L group (0.5 +/- 0.3, P < 0.01). The virtual absence of pathologic changes in the latter group was accompanied by significantly lower endotoxin levels (8.4 +/- 2.9 pg/ml in CO+E+L group vs 48.3 +/- 7.8 pg/ml in CO+E group, P < 0.01). Feeding of strains of lactobacilli that survive in the gastrointestinal tract reduces endotoxemia and alcohol-induced liver injury in the rat. Lactobacillus species GG provides a potential nontoxic form of therapy for both endotoxemia and alcoholic liver disease.

Induction of NF-kappaB-mediated gene expression has been implicated in the pathogenesis of alcoholic liver disease (ALD). Curcumin, a phenolic antioxidant, inhibits the activation of NF-kappaB. We determined whether treatment with curcumin would prevent experimental ALD and elucidated the underlying mechanism. Four groups of rats (6 rats/group) were treated by intragastric infusion for 4 wk. One group received fish oil plus ethanol (FE); a second group received fish oil plus dextrose (FD). The third and fourth groups received FE or FD supplemented with 75 mg. kg(-1). day(-1) of curcumin. Liver samples were analyzed for histopathology, lipid peroxidation, NF-kappaB binding, TNF-alpha, IL-12, monocyte chemotactic protein-1, macrophage inflammatory protein-2, cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and nitrotyrosine. Rats fed FE developed fatty liver, necrosis, and inflammation, which was accompanied by activation of NF-kappaB and the induction of cytokines, chemokines, COX-2, iNOS, and nitrotyrosine formation. Treatment with curcumin prevented both the pathological and biochemical changes induced by alcohol. Because endotoxin and the Kupffer cell are implicated in the pathogenesis of ALD, we investigated whether curcumin suppressed the stimulatory effects of endotoxin in isolated Kupffer cells. Curcumin blocked endotoxin-mediated activation of NF-kappaB and suppressed the expression of cytokines, chemokines, COX-2, and iNOS in Kupffer cells. Thus curcumin prevents experimental ALD, in part by suppressing induction of NF-kappaB-dependent genes.

Increased hepatic oxidative stress with ethanol administration is hypothesized to be caused either by enhanced pro-oxidant production or decreased levels of antioxidants or both. We used the intragastric feeding rat model to assess the relationship between hepatic antioxidant enzymes and pathological liver injury in animals fed different dietary fats. Male Wistar rats (5 per group) were fed ethanol with either medium-chain triglycerides (MCTE), palm oil (PE), corn oil (CE), or fish oil (FE). Control animals were fed isocaloric amounts of dextrose instead of ethanol with the same diets. The following were evaluated in each group: liver pathology, lipid peroxidation, manganese superoxide dismutase (MnSOD) levels, copper-zinc SOD (CuZnSOD) levels, glutathione peroxidase (GPX) levels, and catalase (CAT) levels. All enzymes were evaluated using activity assays and immunoblots. Rats fed FE showed the most severe pathology (fatty liver, necrosis, and inflammation), those fed CE showed moderate changes, those fed PE showed fatty liver only, and those fed MCTE were normal. Parameters indicative of lipid peroxidation (conjugated dienes and thiobarbituric acid-reactive substances) were also greater in rat livers from animals fed the diets high in polyunsaturated fatty acids (CE and FE). CuZnSOD, GPX, and CAT activities showed an inverse correlation (r ‫؍‬ ؊.92, P F .01) with severity of pathological injury, with the lowest levels for both enzymes found in FE-fed rats. Decreased enzyme activity in CE-and FE-fed rats was accompanied by similar decreases in immunoreactive protein. Ethanol administration did not cause significant decreases in enzyme activity in groups that showed no necroinflammatory changes (MCTE and PE). MnSOD activity showed no significant change in any ethanol-fed group. Our results show that decreases in CuZnSOD, GPX, and CAT occur in rats showing pathological liver injury and also having the highest levels of lipid peroxidation. These results suggest that feeding dietary substrates that enhance lipid peroxidation can exacerbate both ethanol-induced oxidative damage as well as necroinflammatory changes. The decrease in activity of antioxidant enzymes observed in animals fed diets high in polyunsaturated fatty acids and ethanol could possibly increase the susceptibility to oxidative damage and further contribute to ethanol-induced liver injury. (HEPATOLOGY 1998;27:1317-1323.)

No abstract