• E Ulfhammer, P Larsson, L Karlsson, T Hrafnkelsdóttir, M Bokarewa, A Tarkowski, and S Jern.
• Clinical Experimental Research Laboratory, Sahlgrenska University Hospital/Ostra, Göteborg University, Göteborg, Sweden.
• J. Thromb. Haemost. 2006 Aug 1;4(8):1781-9.

BackgroundSeveral proatherothrombotic conditions are associated with enhanced levels of circulating proinflammatory cytokines, which are believed to impair endothelial fibrinolytic capacity.ObjectiveThis study aims at investigating how tumor necrosis factor (TNF)-alpha regulates endothelial gene expression of the key fibrinolytic enzyme tissue-type plasminogen activator (t-PA).MethodsCultured human umbilical vein endothelial cells were pretreated with selective inhibitors of the three major inflammatory signaling pathways activated by TNF-alpha; the nuclear factor kappa-B (NF-kappaB), the p38 mitogen-activated protein kinase (p38 MAPK), and the c-jun N-terminal kinase (JNK) pathways. Following TNF-alpha stimulation, effects on t-PA gene expression were evaluated with real-time reverse transcriptase polymerase chain reaction and interactions of nuclear proteins with potential gene regulatory elements were studied with electrophoretic mobility shift assays.ResultsApproximately 50% suppression of t-PA gene expression was observed after prolonged stimulation with TNF-alpha (> or =24 h). The repression was shown to be preferentially dependent on NF-kappaB activation, but also on p38 MAPK signaling. Further, we provide evidence for a TNF-alpha induced binding of NF-kappaB to the recently described kappaB site in the t-PA gene and of cyclic adenosine monophosphate response element binding protein (CREB) to the t-PA CRE-like site.ConclusionsWe conclude that TNF-alpha impairs fibrinolytic capacity in vascular endothelial cells by a NF-kappaB and p38 MAPK-dependent suppression of t-PA. This mechanism sheds a light on how inflammation contributes to the pathogenesis of cardiovascular diseases.

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