Immediate Effects of Fluvastain on Circulating Soluble Endothelial Protein C and Free Tissue Factor Pathway Inhibitor in Acute Coronary Syndromes

Statins and Hemostasis: Therapeutic Potential Based on Clinical Evidence

Hemostasis preserves blood fluidity and prevents its loss after vessel injury. The maintenance of blood fluidity requires a delicate balance between pro-coagulant and fibrinolytic status. Endothelial cells (ECs) in the inner face of blood vessels maintain hemostasis through balancing anti-thrombotic and pro-fibrinolytic activities. Dyslipidemias are linked to hemostatic alterations. Thus, it is necessary a better understanding of the underlying mechanisms linking hemostasis with dyslipidemia. Statins are drugs that decrease cholesterol levels in the blood and are the gold standard for treating hyperlipidemias. Statins can be classified into natural and synthetic molecules, approved for the treatment of hypercholesterolemia. The classical mechanism of action of statins is by competitive inhibition of a key enzyme in the synthesis pathway of cholesterol, the HMG-CoA reductase. Statins are frequently administrated by oral ingestion and its interaction with other drugs and food supplements is associated with altered bioavailability. In this review we deeply discuss the actions of statins beyond the control of dyslipidemias, focusing on the actions in thrombotic modulation, vascular and cardiovascular-related diseases, metabolic diseases including metabolic syndrome, diabetes, hyperlipidemia, and hypertension, and chronic diseases such as cancer, chronic obstructive pulmonary disease, and chronic kidney disease. Furthermore, we were prompted to delved deeper in the molecular mechanisms by means statins regulate coagulation acting on liver, platelets, and endothelium. Clinical evidence show that statins are effective regulators of dyslipidemia with a high impact in hemostasis regulation and its deleterious consequences. However, studies are required to elucidate its underlying molecular mechanism and improving their therapeutical actions.

The effect and molecular mechanism of statins on the expression of human anti-coagulation genes

Statins are potent lipid-lowering drugs. Large prospective clinical trials have shown the anti-thrombotic effect of statins, e.g., preventing deep vein thrombosis. However, the mechanism underlying the beneficial effect of statins in reducing thrombus formation remains to be established. We, thus, conduct this study to investigate the potential molecular mechanisms. The cultured human hepatoma cells (HepG2) were used as the in vitro model. The human protein C gene promoter was cloned into the luciferase reporter to study the transcriptional regulation of human protein C gene. Wistar rats fed with simvastatin (5 mg/kg day) were used as the in vivo model. We found that simvastatin increased the expression of protein C in hepatocytes (361 ± 64% and 313 ± 59% after 2 h and 6 h of stimulation, respectively, both p < 0.01). In the animal study, the serum protein C levels were increased in the simvastatin-treated group (7 ± 2.2 unit/ml vs 23.4 ± 19.3 unit/ml and 23.4 ± 18.2 unit/ml and 1 and 2 weeks of treatment, respectively, both p < 0.05). Regarding the possible molecular mechanism, we found that the level of hepatocyte nuclear factor 1α (HNF1α) was also increased in both the in vivo and in vitro models. We found that the protein C promoter activity was increased by simvastatin, and this effect was inhibited by HNF1α knockdown and constitutively active Rac1. Therefore, stains may modulate protein C expression through small GTPase Rac 1 and HNF1α.

Anti-Thrombotic Effects of Statins in Acute Coronary Syndromes: At the Intersection of Thrombosis, Inflammation, and Platelet-Leukocyte Interactions

HMG CoA reductase inhibitors, or statins, are standard of care for preventing cardiovascular disease in at-risk populations. Statins are a well-established therapy proven to reduce long-term cardiovascular mortality and morbidity for prevention of secondary cardiovascular events and have become guideline-recommended therapy following acute myocardial infarction. Emerging data from clinical trials over the last decade indicates that statin therapy may provide broad beneficial effects beyond their primary lipid lowering mechanisms. In coronary heart disease, statins have demonstrated a unique ability to target several cellular pathways, which appear to play an underappreciated role in acute inflammation and subsequent thrombosis. Herein, we review the potential mechanisms where statins may act as antithrombotic agents in the setting of acute coronary syndromes and discuss the clinical implications of these findings.

Fluvastatin Upregulates the Expression of Tissue Factor Pathway Inhibitor in Human Umbilical Vein Endothelial Cells

AIM

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) are cholesterol-lowering drugs with a variety of pleiotropic effects including antithrombotic properties. Tissue factor pathway inhibitor (TFPI), which is produced predominantly in endothelial cells and platelets, inhibits the initiating phase of clot formation. We investigated the effect of fluvastatin on TFPI expression in cultured endothelial cells.

METHODS

Human umbilical vein endothelial cells (HUVECs) were treated with fluvastatin (0-10μM). The expression of TFPI mRNA and antigen were detected by RT-PCR and western blotting, respectively. The effects of mevalonate intermediates, small GTP-binding inhibitors, and signal transduction inhibitors were also evaluated to identify which pathway was involved. A luciferase reporter assay was performed to evaluate the effect of fluvastatin on TFPI transcription. The stability of TFPI mRNA was estimated by quantitating its levels after actinomycin D treatment.

RESULTS

Fluvastatin increased TFPI mRNA expression and antigen in HUVECs. Fluvastatin-induced TFPI expression was reversed by co-treatment with mevalonate or geranylgeranylpyrophosphate (GGPP). NSC23766 and Y-27632 had no effect on TFPI expression. SB203580, GF109203, and LY294002 reduced fluvastatin-induced TFPI upregulation. Moreover, fluvastatin did not significantly affect TFPI promoter activity. TFPI mRNA degradation in the presence of actinomycin D was delayed by fluvastatin treatment.

CONCLUSIONS

Fluvastatin increases endothelial TFPI expression through inhibition of mevalonate-, GGPP-, and Cdc42-dependent signaling pathways, and activation of the p38 MAPK, PI3K, and PKC pathways. This study revealed unknown mechanisms of the anticoagulant effect of statins and gave a new insight to its therapeutic potential for the prevention of thrombotic diseases.