Lipopolysaccharide-induced E-selectin expression requires continuous presence of LPS and is inhibited by bactericidal/permeability-increasing protein.

Endothelial cells stimulated by LPS express E-selectin, which plays an important role in mediating neutrophil adhesion during inflammation. E-selectin is induced within 1-2 h, peaks at 4-6 h, and gradually returns to basal level by 24 h. rBPI21, a recombinant N-terminal fragment of human bactericidal/permeability-increasing protein (BPI), inhibited LPS-induced E-selectin expression when added at the same time as, and up to 6 h after, LPS. Delayed administration of rBPI21 also affected LPS-mediated activation of the nuclear factor, NF-kappa B. Two to 4 h following LPS addition to endothelial cells, when NF-kappa B was already activated, addition of rBPI21 resulted in marked reduction of NF-kappa B detectable at 4 or 6 h. These results indicate that endothelial activation requires continuous presence of LPS, and rBPI21 acts to reverse LPS-mediated endothelial activation by interrupting the on-going LPS signal.