The anti-thrombotic effects of statins

Chronic venous disease, platelet and haemostatic abnormalities contribute to the pathogenesis of pigmented purpuric dermatoses

Background

To investigate the aetiology of pigmented purpuric dermatoses (PPD).

Methods

63 patients with a provisional diagnosis of PPD were assessed. Skin biopsies were performed to confirm the clinical diagnosis. Haemostasis was assessed using platelet function analyser-100 (PFA-100), light transmission aggregometry (LTA), impedance aggregometry (Multiplate) and measurement of clotting times and clotting factors. Chronic venous disease (CVD) was assessed by duplex ultrasound. When not contraindicated, patients were advised to discontinue haemostatic-modifying drugs or supplements for 4 weeks after which the laboratory measurements were repeated and the clinical resolution of PPD was assessed. Subsequently, a cohort of patients identified with CVD underwent endovenous interventions and further resolution of PPD was assessed.

Results

CVD was found in 48 patients (76.2%) while haemostatic abnormalities were found in 36 (57.1%). 30 patients (47.6%) had concurrent CVD and haemostatic abnormalities. Modifiable risk factors such as the intake of platelet inhibitors or other drugs and supplements such as fish oil were identified in 53 patients (84.1%). These could be ceased in 35 patients of whom 28 (80.0%) achieved either complete or partial resolution of PPD. Treatment of the underlying CVD was performed in 18 patients resulting in complete or partial resolution in 17 (94.4%). In seven patients (11.1%), no CVD or haemostatic abnormalities were identified, and the risk factors included dietary factors such as excessive caffeine or soft drink consumption.

Conclusion

Haemostatic abnormalities and CVD contribute to the pathogenesis of PPD. Resolution of PPD in the vast majority of patients may be achieved by cessation of modifiable risk factors and in particular platelet-modifying drugs or supplements and treatment of the underlying venous disease.

Statins can benefit patients with primary membranous nephropathy on venous thromboembolism

Objective

The aim of this study was to investigate the role of prophylactic use of statin in venous thromboembolism (VTE) in patients with primary membranous nephropathy (PMN).

Methods

A total of 734 patients with PMN were consecutively enrolled in this retrospective study. 564 patients had received statins prescription, while 170 patients did not. Kaplan–Meier methods were used for cumulative incidence plots of thromboembolic events and Cox proportional hazards regression models were used to assess risk factors. Finally, the effects of different potency of statins were evaluated.

Results

In the cohort, 37 patients (5.0%) experienced VTE. In a univariate Cox proportional hazard model, the hazard ratio (HR) for VTE in statin users versus statin non-users was 0.5 (95% CI 0.3–0.8, p = .03). Multivariable model proportional-hazards analysis corrected for co-medications and risk factors revealed that adjusted HR was 0.4 (95% CI 0.1–0.7, p = .03). According to the type and dose, statin users were assigned into 3 groups: high-intensity group (n = 278), moderate-intensity group (n = 186), and low-intensity group (n = 49). In comparison, incidences of VTEs in the three groups were similar (2.9% vs 4.8% vs 2.0%, p = .45).

Conclusions

The prophylactic use of statins could effectively decrease the occurrence of VTE in patients with PMN, and the benefits have no difference in different potency of statins.

Spectrum of pleiotropic effects of statins in heart failure

The syndrome of heart failure is characterized by increased levels of circulating inflammatory mediators, which have been implicated in the pathogenesis of heart failure. Recently, a number of studies have suggested that statins may exert salutary effects in patients who have heart failure by virtue of their pleiotropic (non-lipid lowering) actions. This article focuses on the non-lipid lowering effects of statins, with an emphasis on the anti-inflammatory properties of these agents.

Enhanced nitric oxide and cyclic GMP formation plays a role in the anti-platelet activity of simvastatin

BACKGROUND AND PURPOSE

It has been found that 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) exert various vascular protective effects, beyond their cholesterol-lowering property, including inhibition of platelet-dependent thrombus formation. The objective of the present study was to determine whether the nitric oxide (NO)/cyclic GMP-mediated processes in platelets contribute to the anti-aggregatory activity of simvastatin.

EXPERIMENTAL APPROACH

After rabbit platelets were incubated with simvastatin for 5 min, aggregation was induced and the platelet aggregation, nitric oxide synthase activity, guanylyl cyclase activity, NO and cyclic GMP formation were measured appropriately.

KEY RESULTS

Treatment with simvastatin concentration-dependently inhibited platelet aggregation induced by collagen or arachidonic acid with an IC(50) range of 52-158 microM. We also demonstrated that simvastatin (20-80 microM) concentration-dependently further enhanced collagen-induced NO and cyclic GMP formation through increasing NOS activity (from 2.64+/-0.12 to 3.52+/-0.21-5.10+/-0.14 micromol min(-1) mg protein(-1)) and guanylyl cyclase activity (from 142.9+/-7.2 to 163.5+/-17.5-283.8+/-19.5 pmol min(-1) mg protein(-1)) in the platelets. On the contrary, inhibition of platelet aggregation by simvastatin was markedly attenuated (by about 50%) by addition of a nitric oxide synthase inhibitor, a NO scavenger or a NO-sensitive guanylyl cyclase inhibitor. The anti-aggregatory effects of simvastatin were significantly increased by addition of a selective inhibitor of cyclic GMP phosphodiesterase.

CONCLUSIONS AND IMPLICATIONS

Our findings indicate that enhancement of a NO/cyclic GMP-mediated process plays an important role in the anti-aggregatory activity of simvastatin.

Statin Therapy for Vascular Failure

There is increasing evidence that statins reduce cardiovascular events such as coronary artery disease or stroke in hypercholesterolemic patients in both primary and secondary prevention. The striking benefit achieved with statin treatments in patients with a wide range of cholesterol levels cannot be attributed to their cholesterol lowering effect alone. Substantial data has recently accumulated showing that statins exert various effects on multiple targets, namely pleiotropic effects, especially targeting the concept of 'vascular failure', including the improvement of vascular endothelial function, inhibition of vascular smooth muscle cell proliferation and migration, anti-inflammatory actions, anti-oxidative effects or stabilization of vulnerable plaques. These effects have potential in the treatments of coronary artery disease in various settings, such as prevention of its onset as well as its progression, or plaque rupture. Statin therapy should be more extensively applied even in normolipidemic patients if there are additional risk factors such as hypertension, diabetes mellitus, or others. Furthermore, statins may be used to intervene in earlier stage risk conditions such as postprandial hyperlipidemia or hyperglycemia, insulin resistant state, masked hypertension, or metabolic syndrome to further reduce mortality or morbidity of coronary artery disease and heart failure.

Preferable effect of pravastatin compared to atorvastatin on beta cell function in Japanese early-state type 2 diabetes with hypercholesterolemia

While a large numbers of clinical trials using various kinds of statins has been reported, a possible preventive effect on new onset of type 2 diabetes mellitus was shown only by the subanalysis of The West of Scotland Coronary Prevention Study (WOSCOPS) using pravastatin. The aim of this study was to investigate whether pravastatin has a preferable effect on glucose tolerance among statins. An open-label prospective cross-over trial was performed to compare the effect of pravastatin (10 mg/day) or atorvastatin (10 mg/day) in Japanese early-state type 2 diabetes mellitus with hypercholesterolemia. The analyzed study subjects were treated with pravastatin (10 mg/day, n = 12) or atorvastatin (10 mg/day, n = 12) for 12 weeks. After a 4-week-washout period, the drugs were switched and treatment was continued for another 12 weeks. Oral glucose tolerance test (OGTT) was performed to evaluate several parameters including the appropriateness of beta cell function for the individual insulin sensitivity (disposition index: product of a validated secretion parameter and sensitivity) at the end of each therapy. HbA(1c) and 2 h-glucose levels during OGTT in the pravastatin treatment were significantly lower than atorvastatin treatment. Disposition index after pravastatin treatment was significantly higher than after atorvastatin treatment. In conclusion, our study suggests that pravastatin has a favorable effect on pancreatic beta cell function compared with atorvastatin.

Acute onset and worsening of diabetes concurrent with administration of statins

We report a patient in whom the administration of HMG CoA reductase inhibitors (statins) might have triggered the onset and worsening of diabetes. The patient was a 48-year-old Japanese man who underwent annual medical examination but had never been told of hyperglycemia. Four months after the commencement of atorvastatin (10 mg/day) treatment, a diagnosis of diabetes mellitus was made from his typical symptoms of hyperglycemia, postprandial plasma glucose level of 29.8 mmol/l and HbA1c of 11.5%. After 2 months of insulin therapy and 3 months after the cessation of atorvastatin, almost complete resolution of diabetes was observed. During the subsequent 3 months, diet therapy alone was sufficient to control blood glucose level. Then, we prescribed pravastatin (20 mg/day). During the subsequent 3 months, HbA1c was gradually increased. However, after discontinuation of pravastatin, HbA1c was gradually decreased. In the general population, statin does not seem to have critical adverse effects on glucose tolerance, but it may uncommonly modify the natural course of the development of diabetes in certain patients.

Anti-oxidative effect of fluvastatin in hyperlipidemic type 2 diabetic patients

An open-label prospective cross-over trial was performed to evaluate the antioxidative effect of fluvastatin in Japanese type 2 diabetics with hyperlipidemia. The study subjects were 10 patients who were on pravastatin (10 mg/day) or simvastatin (5 mg/day). After at least 12 weeks of continuous pravastatin or simvastatin therapy, the drugs were washed out for 12 weeks and replaced with fluvastatin (30 mg/day), then the treatment was continued for another 12 weeks. Total cholesterol and LDL cholesterol were efficiently and comparably reduced by all three statin agents. There were no differences in serum parameters of oxidative stress such as malondialdehyde-modified low-density lipoprotein, thiobarbituric acid-reactive substances, and 8-iso-prostaglandin F2alpha between pravastatin/simvastatin and fluvastatin. However, fluvastatin, but not pravastatin/simvastatin, significantly reduced 3,5,7-cholestatriene in erythrocyte membrane, representing the extent of membrane cholesterol peroxidation. Our data demonstrated that fluvastatin has a unique anti-oxidative effect in patients with type 2 diabetes and hyperlipidemia, compared with other statins.

HMG CoA reductase inhibitors and the skeleton: a comprehensive review

Recent studies suggest that the mevalonate pathway plays an important role in skeletal metabolism. HMG CoA reductase inhibitors ("statins"), which inhibit a key enzyme in the mevalonate pathway, are widely used for the treatment of hyperlipidemia. In vitro and animal studies demonstrate that statins stimulate the production of BMP-2, a potent regulator of osteoblast differentiation and activity, suggesting that statins may have an anabolic effect on bone. Statin use in most, but not all observational studies is associated with a reduced risk of fracture, particularly hip fracture, even after adjustment for the confounding effects of age, weight and other medication use. This beneficial effect has not been observed in clinical trials designed to assess cardiovascular endpoints. The effects of statins on bone mass and bone turnover are controversial, but increased bone mass and reduced bone turnover have been observed in controlled studies. Further studies of the skeletal effects of statins are needed, particularly their effects on surrogate markers such as bone mass, bone turnover, and microarchitecture, to determine the optimal formulation, dosing and route of administration. Clinical trials with fracture endpoints are needed before statins can be recommended as therapeutic agents for osteoporosis.

Mechanisms of inhibitory effects of cerivastatin on rat vascular smooth muscle cell growth

The aim of this study was to clarify the mechanism(s) of an inhibitory effect of cerivastatin on cultured rat vascular smooth muscle cell (VSMC) growth. After being starved, cultured VSMCs were stimulated by 5% fetal bovine serum with either various concentrations of cerivastatin or 10-4 M of mevalonate. Cerivastatin dose-dependently decreased the values of [3H]-thymidine incorporation and cell numbers and the level of phosphorylated extracellular signal-regulated protein kinase 1/2. It also suppressed the level of proliferative cell nuclear antigen in a dose-dependent manner. These reductions were abolished by the addition of mevalonate. Similarly, the level of phosphorylated p38 was also decreased by cerivastatin. In contrast, cerivastatin dose-dependently activated the phosphorylation of both c-jun NH2-terminal protein kinase and activating transcription factor-2, and these activations were abolished by the addition of mevalonate. The levels of phosphorylated Akt and p70 S6 kinase as well as those of Bcl-2 were dose-dependently reduced by cerivastatin, and these reductions were abolished by the addition of mevalonate. Cerivastatin could dose-dependently elevate the levels of CPP32/caspase-3 activity and cytoplasmic histone-associated DNA fragments in VSMCs without causing cytotoxicity. These results indicate that cerivastatin suppresses cell survival and activates the apoptotic cellular signaling in VSMCs, suggesting that it could be effective for preventing the progression of restenosis after angioplasty.

Reversal of thrombin-induced deactivation of CD39/ATPDase in endothelial cells by HMG-CoA reductase inhibition: effects on Rho-GTPase and adenosine nucleotide metabolism

Adenosine triphosphate and diphosphate that activate platelet, leukocyte, and endothelium functions are hydrolyzed by endothelial CD39/ATPDase. Because CD39/ATPDase is downregulated in endothelial cells by inflammation and this may be affected by HMG-CoA reductase inhibitors, we examined the role of cerivastatin and simvastatin in regulation of endothelial CD39/ATPDase expression, metabolism of ATP/ADP, and function in platelets. Thrombin-stimulated endothelial cells in vitro were treated with the statins, and hydrolysis of exogenous ADP and ATP was assessed by high-performance liquid chromatography and malachite green assay. Platelet aggregation studies were performed with endothelial cell supernatants as triggers. CD39/ATPDase surface expression by endothelial cells was determined immunologically by fluorescence-activated cell sorter, mRNA expression by RT-PCR, and thrombin-induced dissociation of Rho-GTPases by Western blotting. Treatment by simvastatin or cerivastatin restored impaired metabolism of exogenous ATP and ADP in thrombin-activated endothelial cells by preventing thrombin-induced downregulation of CD39/ATPDase. In platelet aggregation studies, ATP and ADP supernatants of thrombin-activated endothelial cells were less stimulatory in the presence of statins than in their absence. Data show that statins preserve CD39/ATPDase activity in thrombin-treated endothelial cells involving alterations by statins of Rho-GTPase function and CD39/ATPDase expression. Preservation of adenine nucleotide metabolism may directly contribute to the observed anti-thrombotic and anti-inflammatory actions of statins.

Rho-GTPase-dependent platelet-neutrophil interaction affected by HMG-CoA reductase inhibition with altered adenosine nucleotide release and function

Platelet activation and aggregation is considered a crucial step in the initiation and aggravation of arterial thrombosis. ADP from activated platelets is recognized as major factor in thrombus formation and is a potent stimulator of oxygen-free radical release from neutrophils. The aim of the present investigation was to determine in vitro the direct effects of statins on ATP and ADP secretion by platelets and its impact on subsequent oxidative burst activity in neutrophils. Human neutrophils and platelets were isolated from peripheral blood. Levels of platelet-derived ATP and ADP were measured by high-performance liquid chromatography, oxygen-free radical release of neutrophils was measured fluorometrically, and chemotaxis experiments were performed. Rho-GTPases were studied by Western blot analysis. Thrombin-activated platelets primed neutrophils for enhanced oxygen-free radical release on triggering with formyl-Met-Leu-Phe, reduced by cerivastatin and simvastatin treatment of platelets. The two statins decreased the amount of adenosine-derivative release in these cells. Rho-GTPases, required for the thrombin signaling in platelets and neutrophils, were decreased after coincubation with statins. Data demonstrate that inhibition of Rho-GTPases by statins inhibit platelet ADP and ATP release and the consecutive augmentation of neutrophil oxygen-free radical release. Statins affect platelet-neutrophil interactions by altering Rho-GTPase-dependent adenosine nucleotide function.

The role of dyslipidemia and statins in venous thromboembolism

Recent studies have proposed an association between hyperlipidemia and venous thromboembolism (VTE). We review the epidemiological evidence linking dyslipidemia with VTE and examine several possible underlying mechanisms. We discuss the possible role of HMG CoA reductase inhibitors (statins) in the prevention and treatment of VTE and suggest future directions for research.

Atorvastatin upregulates type III nitric oxide synthase in thrombocytes, decreases platelet activation, and protects from cerebral ischemia in normocholesterolemic mice

BACKGROUND AND PURPOSE

Thrombosis superimposed on atherosclerosis causes approximately two thirds of all brain infarctions. We previously demonstrated that statins protect from cerebral ischemia by upregulation of endothelial type III nitric oxide synthase (eNOS), but the downstream mechanisms have not been determined. Therefore, we investigated whether antithrombotic effects contribute to stroke protection by statins.

METHODS

129/SV wild-type and eNOS knockout mice were treated with atorvastatin for 14 days (0.5, 1, and 10 mg/kg). eNOS mRNA from aortas and platelets was measured by reverse-transcriptase polymerase chain reaction. Platelet factor 4 (PF 4) and beta-thromboglobulin (beta-TG) in the plasma were quantified by ELISA. Transient cerebral ischemia was induced by filamentous occlusion of the middle cerebral artery followed by reperfusion.

RESULTS

Stroke volume after 1-hour middle cerebral artery occlusion/23-hour reperfusion was significantly reduced by 38% in atorvastatin-treated animals (10 mg/kg) compared with controls. Serum cholesterol levels were not affected by the treatment. eNOS mRNA was significantly upregulated in a dose-dependent manner in aortas and in thrombocytes of statin-treated mice compared with controls. Moreover, indices of platelet activation in vivo, ie, plasma levels of PF 4 and beta-TG, were dose-dependently downregulated in the treatment group. Surprisingly, atorvastatin-treatment did not influence PF 4 and beta-TG levels in eNOS knockout mice.

CONCLUSIONS

The synthetic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor atorvastatin upregulates eNOS in thrombocytes, decreases platelet activation in vivo, and protects from cerebral ischemia in normocholesterolemic mice. Antithrombotic and stroke-protective effects of statins are mediated in part by eNOS upregulation. Our results suggest that statins may provide a novel prophylactic treatment strategy independent of serum cholesterol levels.

New developments in the treatment of low high-density lipoprotein cholesterol

Reduced levels of high-density lipoprotein (HDL) cholesterol represent an important risk factor for the development and progression of coronary artery disease. In recent years, clinical outcome studies have verified that statin therapy may reduce the risk of initial or recurrent cardiovascular events in subjects with elevated or "normal" cholesterol levels. Subgroup analysis has also revealed that patients with low HDL benefit from this therapy. Two recently presented outcome trials using fibrate therapy also demonstrated a potential role for these medications in subjects with low HDL. The use of various HDL raising agents, singly or in combination on arteriographic progression and their potential mechanisms of action are reviewed. The latter may be an important consideration in the treatment of high-risk patients with low HDL.