Splenectomy attenuates superoxide anion release into the hepatic sinusoids after lipopolysaccharide challenge

Background/Aims: The aim of this study was to determine whether the spleen contributes to superoxide anion release into the hepatic sinusoids and subsequent damage to endothelial cells of the hepatic sinusoids after lipopolysaccharide challenge. Methods: Rats were given 2 mg/kg body weight lipopolysaccharide. Three hours after the treatment, superoxide anion release into the hepatic sinusoids was examined in a liver perfusion model using the cytochrome C method. Damage to endothelial cells of the hepatic sinusoids was assessed from the purine nucleoside phosphorylase/glutamic-pyruvic transaminase ratio in the liver perfusate. To further characterize the mechanisms behind these changes, these studies were done in rats given superoxide dismutase or an anti-TNFα antibody. To study whether the spleen plays a role in the mechanisms, experiments with splenectomized rats were performed. Results: Lipopolysaccharide challenge resulted in superoxide anion release into the hepatic sinusoids and damage to endothelial cells of the hepatic sinusoids. These changes were significantly attenuated by the treatments with superoxide dismutase or an antibody against TNFα, as well as by splenectomy. The hepatic macrophage and Kupffer cell populations after lipopolysaccharide challenge were significantly smaller in the rats given splenectomy than in those given a sham operation. There were no significant differences in the neutrophil populations between the two groups. Levels of TNFα were significantly lower in the former than the latter, whereas there were no significant differences in levels of Interleukin-8 between the two groups. Conclusions: Splenectomy reduced the superoxide anion release into the hepatic sinusoids caused by the lipopolysaccharide challenge and subsequent damage to endothelial cells of the hepatic sinusoids. This supports the view that splenectomy has a protective effect in lipopolysaccharide-induced liver injury.