PYRROLIDINE DITHIOCARBAMATE ABROGATES TISSUE FACTOR (TF) EXPRESSION BY ENDOTHELIAL-CELLS - EVIDENCE IMPLICATING NUCLEAR FACTOR-KAPPA-B IN TP INDUCTION BY DIVERSE AGONISTS

Tissue factor (TF), a 46-kD glycoprotein receptor for coagulation factors VII and VIIa, is expressed on the surface of endothelial cells in response to a variety of agonists and is thought to play an important role in initiating the thrombosis associated with inflammation during infection, sepsis, and organ transplant rejection. The induction of TF activity by lipopolysaccharide (LPS) is regulated, at least partially, at a transcriptional level and an LPS response element containing two activator protein-1 sites and a nuclear factor-kappa B (NF kappa B)-like site has been localized to the 5' flanking region of the TF gene by transfection studies of TF promoter/reporter gene constructs. We have examined the effect of pyrrolidine dithiocarbamate (PDTC), a specific inhibitor of the NF kappa B pathway on the expression of the endogenous TF gene in human umbilical vein endothelial cells (HUVEC). Preincubation of HUVEC for 60 minutes with PDTC inhibited LPS induction of TF activity on the cell surface in a dose-dependent manner, with 50% inhibition occurring at 10 mu mol/L PDTC and 100% inhibition at higher concentrations (greater than or equal to 100 mu mol/L), Furthermore, PDTC inhibited TF expression in response to tumor necrosis factor-alpha, interleukin-1 beta, and phorbol 12-myristate 13-acetate, The effect of PDTC was at the mRNA level, as seen by the complete abrogation of the large increase in TF mRNA observed in LPS-treated HUVEC. These results suggest that endothelial cell activation by diverse agonists initiates intracellular signaling events that converge upon a common pathway involving NF kappa B and, furthermore, that NF kappa B activation is an obligatory step in induction of TF. (C) 1995 by The American Society of Hematology.