Involvement of Kupffer cells in the interaction between neutrophils and sinusoidal endothelial cells in rats

During endotoxic liver injury, large numbers of neutrophils infiltrate the liver, and serum levels of tumor necrosis factor-alpha (TNF-alpha) become elevated. The object of this study was to assess the roles of TNF-alpha secreted by Kupffer cells in the interaction between neutrophils and sinusoidal endothelial cells (SECs). Rat neutrophils were perfused onto SECs that were stimulated with either TNF-alpha or supernatant from lipopolysaccharide (LPS)-stimulated Kupffer cells using an in vitro flow system. Numbers of adhered or migrated neutrophils were counted, and the effect of an antibody against intercellular adhesion molecule-1 (ICAM-1) was studied. Compared with controls (200 +/- 21 cells/mm(2)), neutrophil adhesion to SECs was significantly increased by both TNF-alpha (342 +/- 26 cells/mm(2); P < 0.05) and LPS-stimulated Kupffer cell supernatant (331 +/- 29 cells/mm(2); P < 0.05). Anti-ICAM-1 significantly inhibited neutrophil adhesion (139 +/- 10 cells/mm(2); P < 0.05) and decreased the migration rate of neutrophils on SECs treated with LPS-stimulated Kupffer cell supernatant (P < 0.05). LPS-stimulated Kupffer cells secreted TNF-alpha in an LIDS dose-dependent manner, and they significantly enhanced ICAM-1 expression on SECs (P < 0.05 vs. control). In addition, dexamethasone suppressed TNF-α production by LIPS-stimulated Kupffer cells and decreased ICAM-1 expression and neutrophil adhesion on SECs. These findings suggest that Kupffer cells are involved in neutrophil adhesion and migration in hepatic sinusoids via TNF-α production and induction of ICAM-1 expression on SECs during liver injury associated with endotoxemia.