Increased P-selectin gene expression in the liver vasculature and its role in the pathophysiology of neutrophil-induced liver injury in murine endotoxin shock

We studied the role of P-selectin, an adhesion molecule known to be important for neutrophil localization to sites of inflammation, in a model of inflammatory liver injury. Male C3Heb/FeJ (ET-sensitive) mice treated with 700 mg/kg galactosamine and 100 mu g/kg Salmonella abortus equi endotoxin (Gal/ET), murine tumor necrosis factor alpha (TNF-alpha, 15 mu g/kg), or interleukin-1 (IL-1, 13-23 mu g/kg), showed increased P-selectin mRNA levels in the liver. In contrast, C3H/HeJ (ET-resistant) mice responded only to cytokines with P-selectin mRNA formation. Whereas no P-selectin expression was detectable in control livers, there was temporary staining of endothelium in large blood vessels but not in sinusoids between 3 and 5 h after ET, TNF-alpha, or IL-1 treatment. Severe liver injury induced by Gal/ET at 7 h was not inhibited by an anti-P-selectin antibody in C3Heb/FeJ mice or in P-selectin-deficient animals. Sequestration of neutrophils in sinusoids, i.e. those neutrophils that have been identified as critical for the injury, was not affected by the antibody or in P-selectin-deficient mice, However, the temporary margination in portal and post-sinusoidal venules was reduced by 75% in anti-P-selectin antibody-treated animals and by 51% in P-selectin-deficient mice. We conclude that hepatic P-selectin gene transcription in vivo involves cytokines. However, blocking P-selectin neither attenuated sinusoidal neutrophil sequestration nor prevented neutrophil-induced liver injury during endotoxin shock but attenuated neutrophil margination in larger vessels. Thus, our data demonstrate similarities and fundamental differences in the requirement for adhesion molecules to localize neutrophils in the liver vasculature compared to other organs during an inflammatory response.