Delivery of IkappaB superrepressor gene with adenovirus reduces early alcohol-induced liver injury in rats

Chronic alcohol administration increases gut-derived endotoxin in the portal blood, which activates Kupffer cells through nuclear factor kappaB (NF-kappaB) to produce toxic mediators such as proinflammatory cytokines, leading to liver injury. Therefore, a long-term intragastric ethanol feeding protocol was used here to test the hypothesis that NF-kappaB inhibition would prevent early alcohol-induced liver injury. Adenoviral vectors encoding either the transgene for IkappaB superrepressor (AdIkappaB-SR) or the bacterial beta-galactosidase reporter gene (AdlacZ) were administered intravenously to Wistar rats. Animals were fed a high-fat liquid diet with either ethanol or isocaloric maltose-dextrin (control) for 3 weeks. There was no significant difference in mean urine alcohol concentrations between the groups fed ethanol. IkappaB-SR expression was increased for up to 2 weeks after injection, but was undetectable at 3 weeks. NF-kappaB activation was increased by ethanol and associated with up-regulation of tumor necrosis factor alpha (TNF-alpha). These increases were blunted significantly up to 2 weeks by AdIkappaB-SR. Dietary alcohol significantly increased liver to body weight ratios and serum alanine transaminase (ALT) levels in AdlacZ-treated animals, effects that were blunted significantly in AdIkappaB-SR-treated rats. Ethanol caused severe steatosis, inflammation, and focal necrosis in AdlacZ-treated animals. These pathologic changes were significantly decreased by AdIkappaB-SR. The protective effects of IkappaB-SR were significant 2 weeks after injection, but were lost at 3 weeks when IkappaB-SR was no longer expressed. Ethanol increased 4-hydroxynonenal as a maker of oxidative stress in both AdlacZ and AdIkappaB groups. These data support the hypothesis that NF-kappaB inhibition prevents early alcohol-induced liver injury even in the presence of oxidative stress.