Ethanol-induced alterations in the expression of endothelial-derived fibrinolytic components

Mechanism by which Alcohol and Wine Polyphenols Affect Coronary Heart Disease Risk

The reduction in coronary heart disease (CHD) from moderate alcohol intake may be mediated, in part, by increased fibrinolysis; endothelial cell (EC)-mediated fibrinolysis should decrease acute atherothrombotic consequences (eg, plaque rupture) of myocardial infarction (MI). We have shown that alcohol and individual polyphenols modulate EC fibrinolytic protein (t-PA, u-PA, PAI-1, u-PAR and Annexin-II) expression at the cellular, molecular, and gene levels to sustain increased fibrinolytic activity. Herein we describe the sequence of molecular events by which EC t-PA expression is increased through common activation of p38 MAPK signaling. Up-regulation of t-PA gene transcription, through specific alcohol and polyphenol transcription factor binding sites in the t-PA promoter, results in increased in vitro fibrinolysis and in vivo clot lytic activity (using real-time fluorescence [Fl] imaging of Cy5.5-labeled fibrin clot lysis in a mouse model). Fl-labeled fibrin clots injected into untreated C56Bl/6 wild-type control mice are lysed in approximately 2 hours and clot lytic rates significantly increased in mice treated with either alcohol, catechins, or quercetin (4-6 weeks). Fl-labeled clot lysis in ApoE knock-out mice (atherosclerosis model) showed impaired in vivo clot lysis that was "normalized" to wild-type control levels by treatment with alcohol, catechin, or quercetin for 6 to 8 weeks.

In vitro induction of endothelial cell fibrinolytic alterations by Nigella sativa

The effect of Nigella sativa (NS) L. oil (blackseed oil) on the fibrinolytic system of the human umbilical vein (HUV) and human uterine arterial (HUA) endothelial cells (ECs) in culture was studied. Both of them showed a concentration-dependent increase in tissue-type plasminogen activator (t-PA). A maximum effect was achieved with 50 microg oil/ml conditioned medium (CM) (1.3+/-0.15ng/10(4) cells/24h vs. control 0.7+/-0.06ng/10(4) cells/24h, and 0.38+/-0.04ng/10(4) cells/24h vs. control 0.24+/-0.02ng/10(4) cells/24h, for HUVEC and HUA-EC, respectively). At 100 microg/ml, there was a significant change in the amount of t-PA antigen produced by either HUVEC or HUA-EC (1.0+/-0.1 ng/10(4) cells/24 h or 0.28+/-0.02 ng/10(4) cells/24 h) as compared to control CM from cells grown under control conditions, but still less than that recorded at 50 microg oil/ml. Plasminogen activator inhibitor-type 1 increased the CM significantly and concentration-dependently in both cells. For HUVEC, the maximum effect was achieved at a concentration of 100 microg/ml (257.7+/-8.0 ng/10(4) cells/24 h vs. control 72.7+/-3.8 ng/10(4) cells/24 h). HUA-EC showed the maximum effect at a concentration of 100 microg/ml (171.6+/-4.4 ng/10(4) cells/24 h vs, control 53.8+/-3.7 ng/10(4) cells/24 h). This study suggests a role for NS oil in modulating the balance of fibrinolysis/thrombus formation by modulating the fibrinolytic potential of endothelial cells.

Ethanol downregulates transcription of the PAI-1 gene in cultured human endothelial cells

Human endothelial cells are a major site of synthesis for plasminogen activator inhibitor type-1. Elevated plasminogen activator inhibitor type-1 levels in young survivors of myocardial infarction [1] suggest that plasminogen activator inhibitor type-1 may have an important pathologic role in the development of coronary artery disease. Epidemiological studies indicate that moderate alcohol consumption (1-2 drinks/day) reduces the risk for cardiovascular mortality. This cardioprotective benefit has been attributed in part to an increase in fibrinolysis, which decreases fibrin-based thrombosis. The studies described herein were performed to determine whether moderate levels of ethanol affect plasminogen activator inhibitor type-1 gene expression. Cultured human endothelial cells were exposed to 0.1% v/v ethanol for 1 hour. Following incubation in the absence of ethanol plasminogen activator inhibitor type-1, mRNA levels were decreased in a time- and dose-dependent manner, reaching a maximum decrease of 3- to 4-fold at 2 to 4 hours following ethanol challenge. This decline in mRNA occurs at the transcription level; therefore, nuclear transcription run-on assays were performed. A 2.5- to 5-fold decrease in the rate of plasminogen activator inhibitor type-1 gene transcription was measured at 2 and 4 hours following ethanol challenge. Next, a 3.4- and a 1.1-kb fragment from the plasminogen activator inhibitor type-1 promoter region were linked to a luciferase reporter gene, and these constructs were transfected into human endothelial cells. Treatment of these transiently transfected human endothelial cells with ethanol showed a 2- to 3.5-fold decrease in promoter activity, respectively. These results indicate that low doses of ethanol downregulate transcription of the plasminogen activator inhibitor type-1 gene in cultured human endothelial cells. However, the mechanism(s) for this transcriptional decrease is currently unknown.

Endothelial cell fibrinolysis: transcriptional regulation of fibrinolytic protein gene expression (t-PA, u-PA, and PAI-1) by low alcohol

Epidemiological studies have associated moderate alcohol consumption with a reduced risk for coronary artery disease (CAD) and myocardial infarction (MI). This cardioprotection may be attributed to alcohol-induced changes in a variety of cellular functions, including increased fibrinolysis. Fibrinolysis is important in regulating normal hemostasis. Endothelial cells (ECs) synthesize fibrinolytic proteins, t-PA, u-PA, and PAs inhibitor, PAI-1. Systemic factors, i.e., alcohol, that affect one or more of these components, resulting in increased EC fibrinolysis, will reduce the risk for thrombosis, CAD, and MI and afford cardioprotection. These studies will identify/define the effects of low ethanol (< 0.1%, v/v) on the expression of PAs, PAI-1, and surface-localized fibrinolytic activity in cultured ECs. Low ethanol exerted a short-term time- and dose-dependent increase (approximately 5- to 8-fold) in activity at approximately 20 min and 0.05% ethanol, which was sustained for approximately 1 hr. On the other hand, a single brief exposure to low ethanol (< 0.1%, < 120 min), followed by 4-24 hr incubation in the absence of ethanol, showed a time- and dose-dependent increase (approximately 2- to 3-fold) in PAs antigen/mRNA and a concomitant approximately 2- to 3-fold sustained increase (approximately 24 hr) in fibrinolytic activity. Further nuclear transcription run-on assays and transient transfection experiments, using pPAs/luc and pPAI-1/luc promoter constructs, demonstrated that low ethanol transcriptionally upregulates t-PA and u-PA gene expression and downregulates PAI-1 gene expression. These combined studies have described a feasible molecular mechanism by which low ethanol can induce and sustain increased surface-localized EC fibrinolysis that may underlie and contribute, in part, to the cardioprotective benefit associated with moderate alcohol consumption.