Chelerythrine, a selective protein kinase C inhibitor, counteracts pyrogen-induced expression of tissue factor without effect on thrombomodulin down-regulation in endothelial cells.

Endotoxin, interleukin 1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF-alpha) dose-dependently increased the expression of tissue factor and at the same time induced thrombomodulin down-regulation on the surface of cultured bovine aortic endothelial cells. Chelerythrine, a selective protein kinase C inhibitor, strongly reduced endotoxin-, IL1 beta- and TNF alpha-induced tissue factor expression but remained without effect with regard to thrombomodulin down-regulation measured in parallel. On the contrary, staurosporine, a highly potent, non-selective PKC inhibitor, simultaneously abolished tissue factor expression and thrombomodulin down-regulation induced by endotoxin, IL1 beta and TNF alpha. These results show that protein kinase C is deeply involved in the process leading to pyrogen-induced tissue factor expression and suggest that thrombomodulin down-regulation is regulated by a different pathway.