Sinusoidal endothelial cell injury by superoxide anion and iron in the Propionibacterium acnes-pretreated and lipopolysaccharide-stimulated rat liver

Aims/Background: We attempted to measure the generation of superoxide anion , examine its site of release and determine its pathological role in Propio nibacterium acnes-lipopolysaccharide-induced liver injury in the rat. Metho ds: The P. acnes-pretreated (16 mg/kg i.v.) rat liver was perfused with buf fer containing lipopolysaccharide (2.5 mug/ml). Chemiluminescence enhanced with Cypridina luciferin analog, MCLA, and reduction of nitro blue tetrazol ium were used for detecting superoxide anion. Leakage of enzymes and releas e of cytokines into the perfusate, and histological specimens were also exa mined. Results: Superoxide dismutase-inhibitable chemiluminescence peaked a t 30 min of lipopolysaccharide infusion and blue formazan precipitate was h istochemically deposited mainly on hepatic macrophages. Purine nucleoside p hosphorylase (PNP) activity in the perfusate, as a marker of sinusoidal end othelial cell injury, reached its maximum at 50 min and aspartate aminotran sferase (AST) activity, as a marker of hepatocyte injury, reached a plateau at 90 min. Simultaneous treatment with superoxide dismutase and deferoxami ne mesylate significantly suppressed the leakage of PNP and AST Release of tumor necrosis factor-alpha and growth-related oncogene/cytokine-induced ne utrophil chemoattractant-1 lagged behind PNP leakage. Light microscopy show ed destruction of the sinusoids followed by hepatocyte necrosis. Electron m icroscopy revealed adherence of hepatic macrophages to sinusoidal endotheli al cells. Conclusion: These results indicate that superoxide anion released from hepatic macrophages may induce sinusoidal endothelial cell injury via interaction with iron in the P. acnes-lipopolysaccharide-treated liver.