Pathophysiologic Importance of E– and L–Selectin for Neutrophil–Induced Liver Injury During Endotoxemia in Mice

Abstract

Neutrophils can cause parenchymal cell injury in the liver during ischemia–reperfusion and endotoxemia. Neutrophils relevant for the injury accumulate in sinusoids, transmigrate, and adhere to hepatocytes. To investigate the role of E– and L–selectin in this process, C3Heb/FeJ mice were treated with 700 mg/kg galactosamine and 100 μg/kg endotoxin (Gal/ET). Immunogold labeling verified the expression of E–selectin on sinusoidal endothelial cells 4 hours after Gal/ET injection. In addition, Gal/ET caused up–regulation of Mac–1 (CD11b/CD18) and shedding of L–selectin from circulating neutrophils. Gal/ET induced hepatic neutrophil accumulation (422 ± 32 polymorphonuclear leukocytes [PMN]/50 high power fields [HPF]) and severe liver injury (plasma alanine transaminase [ALT] activities: 4,120 ± 960 U/L; necrosis: 44 ± 3%) at 7 hours. Treatment with an anti-E–selectin antibody (3 mg/kg, intravenously) at the time of Gal/ET administration did not significantly affect hepatic neutrophil accumulation and localization. However, the anti-E–selectin antibody significantly attenuated liver injury as indicated by reduced ALT levels (-84%) and 43% less necrotic hepatocytes. In contrast, animals treated with an anti-L–selectin antibody or L–selectin gene knock out mice were not protected against Gal/ET–induced liver injury. However, E–, L–, and P–selectin triple knock out mice showed significantly reduced liver injury after Gal/ET treatment as indicated by lower ALT levels (-65%) and reduced necrosis (-68%). Previous studies showed that circulating neutrophils of E–selectin-overexpressing mice are primed and activated similar to neutrophils adhering to E–selectin in vitro. Therefore, we conclude that blocking E–selectin or eliminating this gene may have protected against Gal/ET–induced liver injury in vivo by inhibiting the full activation of neutrophils during the transmigration process.