PROTEIN-KINASE-C INHIBITORS BLOCK THE ENHANCED EXPRESSION OF INTERCELLULAR-ADHESION MOLECULE-1 ON ENDOTHELIAL-CELLS ACTIVATED BY INTERLEUKIN-1, LIPOPOLYSACCHARIDE AND TUMOR-NECROSIS-FACTOR

Interleukin 1 (IL-1), bacterial lipopolysaccharide (LPS) and tumor necrosis factor (TNFα) enhance the adherence properties of endothelial cells (EC) for neutrophils (PMN). This is mediated in part by the up-regulation of Intercellular Adhesion Molecule 1 (ICAM-1) on EC. Phorbol esters, which activate protein kinase c (PKC) and enhance the adherence properties of EC for PMN also up-regulate the ICAM-1 expression on EC. We investigated the effect of PKC inhibitors on ICAM-1 expression of human umbilical vein EC (HUVEC). Staurosporine (STS) and 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7) prevented inflammatory mediator-dependent stimulation of both ICAM-1 expression and PMN adherence by HUVEC (ID50 for STS = 2.7-2.9 μM; for H-7 = 7.6-8.8 μM). Inhibition was dose and time-dependent and was not due to HUVEC toxicity. The STS analog K252a and the H-7 analog W-7 were less potent inhibitors of ICAM-1 up-regulation and adherence promotion. Prolonged exposure of HUVEC to phorbol myristate acetate down-regulated PKC activity and inhibited subsequent ICAM-1 up-regulation by this agent and by IL-1. We conclude that inflammatory mediator induced stimulation of HUVEC expression of ICAM-1 and promotion of adherence properties are mediated in part by activation of PKC. © 1990.