Antibodies to tumor necrosis factor alfa attenuate hepatic necrosis and inflammation caused by chronic exposure to ethanol in the rat

Abstract

Tumor necrosis factor (TNF)α, a pivotal cytokine involved in inflammation, is produced primarily by Kupffer cells in the liver. It has been shown that inactivation of Kupffer cells prevents alcohol-induced liver injury; therefore, the purpose of this study was to determine if neutralizing anti-TNF-α antibody is also effective. Male Wistar rats were exposed to ethanol (11 to 12 g · kg-1 · d-1) continuously for up to 4 weeks via intragastric feeding using an enteral feeding model. Before ethanol exposure, polyclonal anti-mouse TNF-α rabbit serum was injected (2.0 mg/kg intravenously). There were no significant differences in body weight, mean ethanol concentration, or cyclic patterns of ethanol in urine when ethanol-and ethanol plus antibody-treated groups were compared. Expression of TNF- α and macrophage inflammatory protein 2 (MIP-2) messenger RNA (mRNA), determined using reverse transcription-polymerase chain reaction, was three- to four-fold higher in livers of ethanol-treated rats than in those of rats fed an ethanol-free, high-fat control diet. In addition, MIP-2 levels were also elevated when detected by Northern blot analysis. Anti-TNF-α antibody did not affect expression of mRNA for interleukin (IL) 1α, IL-6, transforming growth factor β1, or TNF-α. However, MIP-2 mRNA expression, which is regulated by TNF-α, was decreased significantly by anti-TNF-α antibody treatment. Serum aspartate transaminase levels were elevated in ethanol-treated rats to 136 ± 12 IU/L after 4 weeks but only reached 90 ± 5 IU/L (P < .05) in rats treated with anti-TNF-α antibody. The hepatic inflammation and necrosis observed in ethanol-fed rats were attenuated significantly by antibody treatment, and steatosis was not. These results support the hypothesis that TNF-α plays an important role in inflammation and necrosis in alcohol-induced liver injury and that treatment with anti-TNF-α antibody may be therapeutically useful in this disease.