Effects of prostacyclin analogues on human endothelial cell tissue factor expression.

Abstract

Prostacyclin analogues have been reported to inhibit the expression of tissue factor procoagulant activity in human monocytes, primarily by elevating intracellular levels of adenosine 3',5'-cyclic monophosphate (cAMP). The present studies have investigated whether prostacyclins can also inhibit tissue factor expression in endothelial cells. Iloprost, carbacyclin, and ciprostene had no effect on human umbilical vein endothelial tissue factor activity induced by lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF-alpha), or interleukin-1 beta (IL-1 beta). Iloprost failed to elevate intracellular levels of cAMP, even when combined with a phosphodiesterase inhibitor. In contrast, forskolin increased endothelial cAMP and inhibited tissue factor expression. Conditioned medium from LPS-challenged monocytic THP-1 cells, which contained both TNF-alpha and IL-1 beta, induced endothelial cell procoagulant activity to levels 20-fold higher than those achieved in response to LPS alone. Iloprost abolished LPS-induced TNF-alpha secretion by THP-1 cells and inhibited IL-1 beta secretion by 45%. In keeping with this, iloprost reduced levels of TNF-alpha and IL-1 beta mRNA in LPS-challenged cells. Treatment of THP-1 cells with iloprost strongly inhibited the ability of conditioned medium to induce endothelial tissue factor expression, an effect that was mimicked by treating the medium with blocking antibodies to the cytokines. We conclude that although prostacyclin analogues do not directly suppress endothelial tissue factor expression due to their failure to elevate cAMP, they may do so indirectly by inhibiting the amplification produced by monocyte-derived cytokines.

Elevated Cyclic AMP Inhibits NF-κB-mediated Transcription in Human Monocytic Cells and Endothelial Cells

“…In addition, agents such as dibutyryl cAMP (Bt 2 cAMP), forskolin, and isobutylmethylxanthine, which increase cAMP levels by independent mechanisms, all inhibit induction of TF expression (29,30). In endothelial cells, elevation of cAMP and activation of PKA inhibit cytokine induction of E-selectin, VCAM-1, and TF expression (21,22,31). Studies using both monocytes and endothelial cells indicate that cAMP inhibits transcription of this distinct set of genes (21,23,25,30).…”

Endothelial dysfunction and activation as an expression of disease: role of prostacyclin analogs

“…PGI2 analogs are able to regulate TNF-alpha synthesis in leukocytes and in macrophages [254][255][256], are potent stimulators of ICAM-1 and VCAM-1 expression on EC, indirectly regulating the expression of these adhesion molecules. PGI2 analogs also downregulate mitogen-activated protein kinases of macrophages [257] and decrease the tissue factor expression in monocytes and EC, via elevation of intracellular levels of cyclic AMP [258,259].…”

Human Umbilical Vein Smooth Muscle Cells as a Model to Study Thrombin Generation and Function: Effect of Thrombin Inhibitors

“…The procoagulant activity was assessed on the surface of intact monolayers as previously described (36). HUVSMC were grown to confluence in 12-well gelatin-coated plates.…”