ObjectiveGabexate mesilate, a synthetic protease inhibitor, has been shown to reduce endotoxin-induced pulmonary vascular injury in an animal model of sepsis by inhibiting leukocyte activation. We examined whether gabexate mesilate inhibits tumor necrosis factor-&agr;-induced expression of leukocyte adhesion molecules in cultured endothelial cells.DesignProspective, randomized, controlled study.SettingResearch laboratory at a university medical centerSubjectsCultured human umbilical vein endothelial cell (HUVECs).InterventionsHUVECs were stimulated with tumor necrosis factor-&agr; or lipopolysaccharide in the presence or absence of gabexate mesilate. Expression of E-selectin and intercellular adhesion molecule-1 was measured by cellular enzyme-linked immunosorbent assay. Messenger RNA levels of E-selectin and intercellular adhesion molecule-1 were determined by reverse transcription-polymerase chain reaction. DNA-binding activity of p65 in the nuclear extracts was evaluated by enzyme-linked immunosorbent assay. Nuclear translocation of nuclear factor-&kgr;B induced by tumor necrosis factor-&agr; was evaluated by immunocytostaining and Western blot analysis. Degradation and phosphorylation of inhibitor of nuclear factor-&kgr;B (I&kgr;B) induced by tumor necrosis factor-&agr; were evaluated by Western blot analysis.Measurements and Main ResultsGabexate mesilate inhibited the tumor necrosis factor-&agr;-induced increases in the endothelial expression of E-selectin and intercellular adhesion molecule-1 by inhibiting the transcription. Tumor necrosis factor-&agr;-induced increase in DNA binding of p65 was inhibited by gabexate mesilate through inhibition of the nuclear translocation of p65. Gabexate mesilate inhibited the tumor necrosis factor-&agr;-induced degradation of I&kgr;B&agr;, an inhibitor of nuclear factor-&kgr;B, by inhibiting phosphorylation of I&kgr;B&agr; in HUVECs.ConclusionsGabexate mesilate inhibited the expression of leukocyte adhesion molecules by inhibiting the nuclear factor-&kgr;B-mediated transcription in HUVECs. Inhibition of nuclear factor-&kgr;B activation by gabexate mesilate could be explained by inhibition of degradation of I&kgr;B. Gabexate mesilate might reduce lipopolysaccharide-induced pulmonary vascular injury not only by inhibiting monocytic tumor necrosis factor-&agr; production but by inhibiting the expression of endothelial leukocyte adhesion molecules.