Immediate Antioxidant and Antiplatelet Effect of Atorvastatin via Inhibition of Nox2

Urinary 11-dehydro-thromboxane B2 is associated with cardiovascular events and mortality in patients with atrial fibrillation

BACKGROUND

Patients with nonvalvular atrial fibrillation (AF) show high residual cardiovascular (CV) risk despite oral anticoagulants. Urinary 11-dehydro-thromboxane B2 (TxB2) is associated with an increased risk of CV events (CVEs), but its predictive value in patients with anticoagulated AF is unknown.

METHODS

A prospective single-center cohort study, including 837 patients with AF, was conducted. Mean time of follow-up was 30.0 months, yielding 2,062 person-years of observation. Urinary 11-dehydro-TxB2 was measured at baseline. The primary end point was the occurrence of a CVE including fatal/nonfatal myocardial infarction and ischemic stroke, transient ischemic attack, cardiac revascularization, and CV death.

RESULTS

Mean age of patients was 73.1 years, and 43.6% were women. Median 11-dehydro-TxB2 levels were 100 (interquartile range 50-187) ng/mg of urinary creatinine. Overall, the anticoagulation control was adequate (63.9% of mean time in therapeutic range). A CVE occurred in 99 (11.8%) patients, and 55 were CV deaths. At baseline, 11-dehydro-TxB2 levels were higher in patients with a CVE compared with those without (186 [107-400] vs 98 [52-170], P < .001). An increased rate of CVEs (log-rank test, P < .001) and CV deaths (P < .001) was observed across tertiles of 11-dehydro-TxB2. Cardiovascular events were associated with age (hazard ratios [HR] 1.72 per 1 SD, 95% CI 1.33-2.21, P < .001), diabetes mellitus (HR 1.89, 95% CI 1.20-2.96, P = .005), heart failure (HR 1.60, 95% CI 1.01-2.54, P = .044), history of stroke/transient ischemic attack (HR 1.96, 95% CI 1.25-3.06, P = .003), and 11-dehydro-TxB2 (HR 1.64 per 1 SD, 95% CI 1.42-1.89, P < .001).

CONCLUSIONS

Urinary 11-dehydro-TxB2 levels are associated with a residual risk of CVEs and CV mortality in patients with AF despite anticoagulant treatment.

Clinical Application of NOX Activity and Other Oxidative Biomarkers in Cardiovascular Disease: A Critical Review

SIGNIFICANCE

The oxidative stress theory of atherosclerosis is based on the assumption that the production of reactive oxidant species (ROS) by blood, as well as resident cells of the artery wall, elicits the formation of oxidized low-density lipoproteins (ox-LDL), which, in turn, promotes a series of inflammatory responses, ultimately leading to atherosclerotic plaque. This theory prompted the development of new laboratory methodologies that aimed at assessing the relationship between oxidative stress and clinical progression of human atherosclerosis.

CRITICAL ISSUES

Markers assessing the oxidation of phospholipid and protein components of LDL were among the first to be developed. Clinical trials included cross-sectional as well as retrospective and prospective studies that, however, provided equivocal results. Thus, clear evidence that oxidative biomarkers add more to the risk stratification by common atherosclerotic risk factors is still lacking.

RECENT ADVANCES

More recently, the analysis of oxidative stress focused on enzymatic pathways generating ROS, such as NADPH oxidase and myeloperoxidase (MPO). Experimental and clinical studies suggest that both enzymes may be implicated in promoting atherosclerotic disease. Novel laboratory methodologies have been, therefore, developed to study NADPH oxidase and MPO in patients with stable atherosclerosis as well as in patients with acute coronary and cerebro-vascular syndromes.

FUTURE DIRECTIONS

This review will analyze the strengths and weaknesses of the current methodology to study these enzymes in human atherosclerosis with particular regard to their clinical application in several settings of cardiovascular disease. Clinical methodology and results of previous studies with regard to markers of LDL oxidation have also been reviewed as a useful background for the future development of clinical trials.

Extra virgin olive oil use is associated with improved post-prandial blood glucose and LDL cholesterol in healthy subjects

OBJECTIVES

Extra virgin olive oil (EVOO) is a key component of the Mediterranean diet and seems to account for the protective effect against cardiovascular disease. However, the underlying mechanism is still elusive.

DESIGN

We tested the effect of EVOO, added to Mediterranean-type meal, on post-prandial glycemic and lipid profile.

SUBJECTS

Post-prandial glycemic and lipid profile were investigated in 25 healthy subjects who were randomly allocated in a cross-over design to a Mediterranean-type meal added with or without 10 g EVOO (first study), or Mediterranean-type meal with EVOO (10 g) or corn oil (10 g; second study). Glycemic profile, which included glucose, insulin, dipeptidyl-peptidase-4 (DPP-4) protein and activity, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), and lipid profile, which included, low-density lipoprotein (LDL) cholesterol (LDL-C), oxidized LDL (ox-LDL), triglycerides and high-density lipoprotein (HDL) cholesterol (HDL-C), were analyzed before and 2 h after the meal.

RESULTS

In the first study, 2 h after meal, subjects who assumed a meal with EVOO had significantly lower blood glucose (P<0.001), DPP-4 protein (P<0.001) and activity (P<0.001), LDL-C (P<0.001) and ox-LDL (P<0.001) and higher insulin (P<0.05), GLP-1 (P<0.001) and GIP (P<0.05) compared with those without EVOO. The second study showed that compared with corn oil, EVOO improved both glycemic and lipid profile. Thus, a significantly smaller increase of glucose (P<0.05), DPP4 protein (P<0.001) and activity (P<0.05) and higher increase of insulin (P<0.001) and GLP-1 (P<0.001) were observed. Furthermore, compared with corn oil, EVOO showed a significantly less increase of LDL-C (P<0.05) and ox-LDL (P<0.001).

CONCLUSIONS

We report for the first time that EVOO improves post-prandial glucose and LDL-C, an effect that may account for the antiatherosclerotic effect of the Mediterranean diet.

Incidence of myocardial infarction and vascular death in elderly patients with atrial fibrillation taking anticoagulants: relation to atherosclerotic risk factors

BACKGROUND

Recent findings suggest that patients with atrial fibrillation (AF), in addition being at thromboembolic risk, are at risk of myocardial infarction (MI). Our aim was to investigate predictors of MI and cardiovascular death in a cohort of patients with AF who were taking anticoagulants.

METHODS

We prospectively followed up 1,019 patients with AF for a median of 33.7 months (3,223 person-years). All patients were treated with oral vitamin K antagonists. Primary outcome was a composite end point of cardiovascular events (CVEs) including fatal/nonfatal MI, cardiac revascularization, and cardiovascular death.

RESULTS

The mean age of the patients was 73.2 years, and 43.8% were women. At follow-up, 111 CVEs (3.43%/y) had occurred: 47 fatal-nonfatal MI/revascularization and 64 cardiovascular deaths. In addition, 31 stroke/transient ischemic attacks (0.96%/y) were recorded. Patients experiencing CVEs were older (P < .001) and had a higher prevalence of metabolic syndrome (MetS) (P = .005), heart failure (P = .001), and prior cardiac (P < .001) and cerebrovascular events (P < .001). On a Cox proportional hazard analysis, age (hazard ratio [HR], 1.083; 95% CI, 1.053-1.113; P < .001), smoking (HR, 2.158; 95% CI, 1.193-3.901; P = .011), history of cerebrovascular (HR, 1.704; 95% CI, 1.119-2.597; P = .013) and cardiac (HR, 1.658; 95% CI, 1.105-2.489; P = .015) events, MetS (HR, 1.663; 95% CI, 1.107-2.499; P = .014), heart failure (HR, 1.584; 95% CI, 1.021-2.456; P = .040), and male sex (HR, 1.499; 95% CI, 1.010-2.223; P = .044) predicted CVEs.

CONCLUSIONS

Patients with AF still experience a high rate of CVEs despite receiving anticoagulant treatment. MetS is a common clinical feature in patients with AF, which increases the risk of CVEs. A holistic approach is needed to reduce the cardiovascular risk in patients with AF.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01882114; URL: www.clinicaltrials.gov.

Low dose of acetylsalicylic acid and oxidative stress-mediated endothelial dysfunction in diabetes: a short-term evaluation

Current guidelines suggest the use of low doses of acetylsalicylic acid (ASA) for patients with diabetes mellitus (DM) in primary prevention. However, the evidences demonstrating the beneficial effect of ASA in primary prevention are conflicting. In this pilot study, we evaluated in a group of diabetic patients, in primary prevention, the impact of ASA treatment on oxidative stress and vascular function. We enrolled 22 newly diagnosed diabetic patients, without any previous clinical evidence of cardiovascular disease, to receive, in primary prevention, ASA (100 mg/daily). We tested, in basal condition, after 4 weeks of ASA administration and after 4 weeks of pharmacological washout, the impact of ASA treatment on endothelial function, assessed by a semipletysmographic method, measuring the main oxidative stress parameters related to it. As expected, after 4 weeks of treatment, ASA induced a significant reduction of plasma thromboxane-A2, as a consequence of cyclooxygenase-1 inhibition. By contrast, ASA significantly increased the plasma and urine 8-iso-PGF2α, a well-known prothrombotic molecule, parallel to an increase of plasma NOX2 levels. The enhancement of this oxidative pathway is associated with a significant impairment of endothelial vasodilation, assessed by reactive hyperemia index (RHI). The pharmacological washout reverted all parameters to basal condition. Our findings suggest that ASA utilization for primary prevention in diabetic patients causes a significant increase of oxidative stress burden impairing the vascular function. Present data, if confirmed on a larger population, could permanently discourage the use of the ASA for the primary prevention in patients with DM.

Vascular injury in diabetic db/db mice is ameliorated by atorvastatin: role of Rac1/2-sensitive Nox-dependent pathways

Oxidative stress [increased bioavailability of reactive oxygen species (ROS)] plays a role in the endothelial dysfunction and vascular inflammation, which underlie vascular damage in diabetes. Statins are cholesterol-lowering drugs that are vasoprotective in diabetes through unknown mechanisms. We tested the hypothesis that atorvastatin decreases NADPH oxidase (Nox)-derived ROS generation and associated vascular injury in diabetes. Lepr(db)/Lepr(db) (db/db) mice, a model of Type 2 diabetes and control Lepr(db)/Lepr(+) (db/+) mice were administered atorvastatin (10 mg/kg per day, 2 weeks). Atorvastatin improved glucose tolerance in db/db mice. Systemic and vascular oxidative stress in db/db mice, characterized by increased plasma TBARS (thiobarbituric acid-reactive substances) levels and exaggerated vascular Nox-derived ROS generation respectively, were inhibited by atorvastatin. Cytosol-to-membrane translocation of the Nox regulatory subunit p47(phox) and the small GTPase Rac1/2 was increased in vessels from db/db mice compared with db/+ mice, an effect blunted by atorvastatin. The increase in vascular Nox1/2/4 expression and increased phosphorylation of redox-sensitive mitogen-activated protein kinases (MAPKs) was abrogated by atorvastatin in db/db mice. Pro-inflammatory signalling (decreased IκB-α and increased NF-κB p50 expression, increased NF-κB p65 phosphorylation) and associated vascular inflammation [vascular cell adhesion molecule-1 (VCAM-1) expression and vascular monocyte adhesion], which were increased in aortas of db/db mice, were blunted by atorvastatin. Impaired acetylcholine (Ach)- and insulin (INS)-induced vasorelaxation in db/db mice was normalized by atorvastatin. Our results demonstrate that, in diabetic mice, atorvastatin decreases vascular oxidative stress and inflammation and ameliorates vascular injury through processes involving decreased activation of Rac1/2 and Nox. These findings elucidate redox-sensitive and Rac1/2-dependent mechanisms whereby statins protect against vascular injury in diabetes.

Oxidative stress-related mechanisms affecting response to aspirin in diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a major cardiovascular risk factor. Persistent platelet activation plays a key role in atherothrombosis in T2DM. However, current antiplatelet treatments appear less effective in T2DM patients vs nondiabetics at similar risk. A large body of evidence supports the contention that oxidative stress, which characterizes DM, may be responsible, at least in part, for less-than-expected response to aspirin, with multiple mechanisms acting at several levels. This review discusses the pathophysiological mechanisms related to oxidative stress and contributing to suboptimal aspirin action or responsiveness. These include: (1) mechanisms counteracting the antiplatelet effect of aspirin, such as reduced platelet sensitivity to the antiaggregating effects of NO, due to high-glucose-mediated oxidative stress; (2) mechanisms interfering with COX acetylation especially at the platelet level, e.g., lipid hydroperoxide-dependent impaired acetylating effects of aspirin; (3) mechanisms favoring platelet priming (lipid hydroperoxides) or activation (F2-isoprostanes, acting as partial agonists of thromboxane receptor), or aldose-reductase pathway-mediated oxidative stress, leading to enhanced platelet thromboxane A2 generation or thromboxane receptor activation; (4) mechanisms favoring platelet recruitment, such as aspirin-induced platelet isoprostane formation; (5) modulation of megakaryocyte generation and thrombopoiesis by oxidative HO-1 inhibition; and (6) aspirin-iron interactions, eventually resulting in impaired pharmacological activity of aspirin, lipoperoxide burden, and enhanced generation of hydroxyl radicals capable of promoting protein kinase C activation and platelet aggregation. Acknowledgment of oxidative stress as a major contributor, not only of vascular complications, but also of suboptimal response to antiplatelet agents in T2DM, may open the way to designing and testing novel antithrombotic strategies, specifically targeting oxidative stress-mediated mechanisms of less-than-expected response to aspirin.

Statins improve the resolution of established murine venous thrombosis: reductions in thrombus burden and vein wall scarring

Despite anticoagulation therapy, up to one-half of patients with deep vein thrombosis (DVT) will develop the post-thrombotic syndrome (PTS). Improving the long-term outcome of DVT patients at risk for PTS will therefore require new approaches. Here we investigate the effects of statins—lipid-lowering agents with anti-thrombotic and anti-inflammatory properties—in decreasing thrombus burden and decreasing vein wall injury, mediators of PTS, in established murine stasis and non-stasis chemical-induced venous thrombosis (N = 282 mice). Treatment of mice with daily atorvastatin or rosuvastatin significantly reduced stasis venous thrombus burden by 25% without affecting lipid levels, blood coagulation parameters, or blood cell counts. Statin-driven reductions in VT burden (thrombus mass for stasis thrombi, intravital microscopy thrombus area for non-stasis thrombi) compared similarly to the therapeutic anticoagulant effects of low molecular weight heparin. Blood from statin-treated mice showed significant reductions in platelet aggregation and clot stability. Statins additionally reduced thrombus plasminogen activator inhibitor-1 (PAI-1), tissue factor, neutrophils, myeloperoxidase, neutrophil extracellular traps (NETs), and macrophages, and these effects were most notable in the earlier timepoints after DVT formation. In addition, statins reduced DVT-induced vein wall scarring by 50% durably up to day 21 in stasis VT, as shown by polarized light microscopy of picrosirius red-stained vein wall collagen. The overall results demonstrate that statins improve VT resolution via profibrinolytic, anticoagulant, antiplatelet, and anti-vein wall scarring effects. Statins may therefore offer a new pharmacotherapeutic approach to improve DVT resolution and to reduce the post-thrombotic syndrome, particularly in subjects who are ineligible for anticoagulation therapy.

Ultrastructure and composition of thrombi in coronary and peripheral artery disease: correlations with clinical and laboratory findings

INTRODUCTION

Fibrin structure and cellular composition of thrombi profoundly affect the clinical outcomes in ischemic coronary and peripheral artery disease. Our study addressed the interrelations of structural features of thrombi and routinely measured laboratory parameters.

MATERIALS AND METHODS

Thrombi removed by thromboaspiration following acute myocardial infarction (n=101) or thrombendarterectomy of peripheral arteries (n=50) were processed by scanning electron microscopy and immunostaining for fibrin and platelet antigen GPIIb/IIIa to determine fibrin fibre diameter and relative occupancy by fibrin and cells. Correlations between the structural characteristics and selected clinical parameters (age, sex, vascular localization, blood cell counts, ECG findings, antiplatelet medication, accompanying diseases, smoking) were assessed.

RESULTS

We observed significant differences in mean fibre diameter (122 vs. 135 nm), fibrin content (70.5% vs. 83.9%), fluorescent fibrin/platelet coverage ratio (0.18 vs. 1.06) between coronary and peripheral thrombi. Coronary thrombi from smokers contained more fibrin than non-smokers (78.1% vs. 62.2% mean occupancy). In the initial 24 h, fibrin content of coronary thrombi decreased with time, whereas in peripheral thrombi platelet content increased in the first 7 days. In coronaries, higher platelet content and smaller vessel diameter were associated with thinner fibrin fibres, whereas hematocrit higher than 0.35 correlated with larger intrathrombotic platelet occupancy. Smoking and dyslipidaemia strengthened the dependence of clot platelet content on systemic platelet count (the adjusted determination coefficient increased from 0.33 to 0.43 and 0.65, respectively).

CONCLUSION

Easily accessible clinical parameters could be identified as significant determinants of ultrastructure and composition of coronary and peripheral thrombi.

The efficacy and safety of statins for the treatment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease is an emerging liver disease in Western countries and the most frequent cause of incidental elevation of serum liver enzymes. Dyslipidaemia is frequently observed in patients with non-alcoholic fatty liver disease, and treatment of dyslipidaemia plays a critical role in the overall management of these patients. Moreover, coronary artery disease remains the most common cause of death. Statins are effective lipid-lowering agents, associated with a lowering the risk of cardiovascular events in several interventional randomized clinical trials. However, statins are often underused in patients with non-alcoholic fatty liver disease and many physicians are concerned about the prescription of statins to patients with unexplained persistent elevation of liver enzymes or active liver disease. Based on currently available data, statin therapy, at low-to-moderate doses, seems to be safe and has low liver toxicity. Treatment of dyslipidaemia in patients with non-alcoholic fatty liver disease is recommended and may also improve liver function tests. In these patients, the risks of not taking statins could outweigh the risks of taking the drug. Conversely, the usefulness of statins for the treatment of non-alcoholic fatty liver disease/non-alcoholic steatohepatitis is still a matter of debate and randomized clinical trials of adequate size and duration are required.

High levels of LDL-C combined with low levels of HDL-C further increase platelet activation in hypercholesterolemic patients

High levels of low-density lipoprotein cholesterol (LDL-C) enhance platelet activation, whereas high levels of high-density lipoprotein cholesterol (HDL-C) exert a cardioprotective effect. However, the effects on platelet activation of high levels of LDL-C combined with low levels of HDL-C (HLC) have not yet been reported. We aimed to evaluate the platelet activation marker of HLC patients and investigate the antiplatelet effect of atorvastatin on this population. Forty-eight patients with high levels of LDL-C were enrolled. Among these, 23 had HLC and the other 25 had high levels of LDL-C combined with normal levels of HDL-C (HNC). A total of 35 normocholesterolemic (NOMC) volunteers were included as controls. Whole blood flow cytometry and platelet aggregation measurements were performed on all participants to detect the following platelet activation markers: CD62p (P-selectin), PAC-1 (GPIIb/IIIa), and maximal platelet aggregation (MPAG). A daily dose of 20 mg atorvastatin was administered to patients with high levels of LDL-C, and the above assessments were obtained at baseline and after 1 and 2 months of treatment. The expression of platelets CD62p and PAC-1 was increased in HNC patients compared to NOMC volunteers (P<0.01 and P<0.05). Furthermore, the surface expression of platelets CD62p and PAC-1 was greater among HLC patients than among HNC patients (P<0.01 and P<0.05). Although the expression of CD62p and PAC-1 decreased significantly after atorvastatin treatment, it remained higher in the HLC group than in the HNC group (P<0.05 and P=0.116). The reduction of HDL-C further increased platelet activation in patients with high levels of LDL-C. Platelet activation remained higher among HLC patients regardless of atorvastatin treatment.

Serum NOX2 and urinary isoprostanes predict vascular events in patients with atrial fibrillation

There are limited prospective data evaluating the role of urinary F2-IsoP and NOX2 as predictive markers in atrial fibrillation (AF). The aim of this study was to analyse the role of urinary prostaglandin PGF2alpha (8-iso-PGF2α) and NOX2, markers of systemic oxidative stress, in predicting cardiovascular (CV) events and mortality in anticoagulated non-valvular AF patients. This was a prospective study including 1,002 anticoagulated AF patients, followed for a median time of 25.7 months (interquartile range: 14.8-50.9). All major CV events, CV deaths and all-cause deaths were considered as primary outcomes of the study. CV events included fatal/nonfatal ischaemic stroke, fatal/nonfatal myocardial infarction (MI), cardiac revascularisation and transient ischaemic attack (TIA). Oxidative stress biomarkers, such as urinary 8-iso-PGF2α and serum sNOX2-dp, a marker of NOX2 activation, were measured. A CV event occurred in 125 patients (12.5 %); 78 CV deaths and 31 non-CV deaths were registered. 8-iso-PGF2α and sNOX2-dp were correlated (Rs=0.765 p< 0.001). A significant increased cumulative incidence of CV events and CV deaths was observed across tertiles for 8-iso-PGF2α and sNOX2-dp. An increased rate of all-cause death was observed across tertiles of urinary 8-iso-PGF2α. In Cox or Fine and Gray models, 8-iso-PGF2α predicted CV events and CV and non-CV deaths. The addition of tertiles of 8-iso-PGF2α to CHA2DS2-VASc score improved ROC curves for each outcome and NRI for CV events (0.24 [0.06-0.53] p=0.0067). The study shows that in AF patients 8-iso-PGF2α and NOX2 levels are predictive of CV events and total mortality. F2-IsoP may complement conventional risk factors in prediction of CV events.

The antithrombotic effects of statins

Hypercholesterolemia is considered the primary risk factor for cardiovascular disease. An estimated 200 million prescriptions are issued per year for statins to treat hypercholesterolemia. Importantly, statins have additional beneficial effects independent of their effects on lipids. Recent studies have shown that statins reduce thrombosis via multiple pathways, including inhibiting platelet activation and reducing the pathologic expression of the procoagulant protein tissue factor. Many of the antithrombotic effects of statins are attributed to inhibiting prenylation of RhoA and effects on other intracellular signaling molecules such as NF-κB and KLF2. These antithrombotic activities of statins likely contribute to the ability of statins to reduce the incidence of cardiovascular death.

Pneumonia, thrombosis and vascular disease

SUMMARY

An enhanced risk of cardiovascular mortality has been observed after pneumonia. Epidemiological studies have shown that respiratory tract infections are associated with an increased risk of thrombotic-related vascular disease such as myocardial infarction, ischemic stroke and venous thrombosis. Myocardial infarction and stroke have been detected essentially in the early phase of the disease (i.e. within 48 h from hospital admission), with an incidence ranging from as low as 1% to as high as 11%. Age, previous cardiovascular events and high pneumonia severity index were independent predictors of myocardial infarction; clinical predictors of stroke were not identified. Deep venous thrombosis and pulmonary embolism may also occur after pneumonia but incidence and clinical predictors must be defined. The biological plausibility of such an association may be deduced by experimental and clinical studies, showing that lung infection is complicated by platelet aggregation and clotting system activation, as documented by up-regulation of tissue factor and down-regulation of activated protein C. The effect of antithrombotic drugs has been examined in experimental and clinical studies but results are still inconclusive.

Antioxidant effects of statins in the management of cardiometabolic disorders

Redox systems are key players in vascular health. A shift in redox homeostasis-that results in an imbalance between reactive oxygen species (ROS) generation and endogenous antioxidant defenses has the potential to create a state of oxidative stress that subsequently plays a role in the pathogenesis of a number of diseases, including those of the cardiovascular and metabolic system. Statins, which are primarily used to reduce the concentration of low-density lipoprotein cholesterol, have also been shown to reduce oxidative stress by modulating redox systems. Studies conducted both in vitro and in vivo support the role of oxidative stress in the development of atherosclerosis and cardiovascular diseases. Oxidative stress may also be responsible for various diabetic complications and the development of fatty liver. Statins reduce oxidative stress by blocking the generation of ROS and reducing the NAD+/NADH ratio. These drugs also have effects on nitric oxide synthase, lipid peroxidation and the adiponectin levels. It is possible that the antioxidant properties of statins contribute to their protective cardiovascular effects, independent of the lipid-lowering actions of these agents. However, possible adverse effects of statins on glucose homeostasis may be related to the redox system. Therefore, studies investigating the modulation of redox signaling by statins are warranted.

Platelets and their chemokines in atherosclerosis-clinical applications

The concept of platelets as important players in the process of atherogenesis has become increasingly accepted due to accumulating experimental and clinical evidence. Despite the progress in understanding the molecular details of atherosclerosis, particularly by using animal models, the inflammatory and thrombotic roles of activated platelet s especially in the human system remain difficult to dissect, as often only the complications of atherosclerosis, i.e., stroke and myocardial infarction are definable but not the plaque burden. Platelet indices including platelet count and mean platelet volume (MPV) and soluble mediators released by activated platelets are associated with atherosclerosis. The chemokine CXCL4 has multiple atherogenic activities, e.g., altering the differentiation of T cells and macrophages by inhibiting neutrophil and monocyte apoptosis and by increasing the uptake of oxLDL and synergizing with CCL5. CCL5 is released and deposited on endothelium by activated platelets thereby triggering atherogenic monocyte recruitment, which can be attenuated by blocking the corresponding chemokine receptor CCR5. Atheroprotective and plaque stabilizing properties are attributed to CXCL12, which plays an important role in regenerative processes by attracting progenitor cells. Its release from luminal attached platelets accelerates endothelial healing after injury. Platelet surface molecules GPIIb/IIIa, GP1bα, P-selectin, JAM-A and the CD40/CD40L dyade are crucially involved in the interaction with endothelial cells, leukocytes and matrix molecules affecting atherogenesis. Beyond the effects on the arterial inflammatory infiltrate, platelets affect cholesterol metabolism by binding, modifying and endocytosing LDL particles via their scavenger receptors and contribute to the formation of lipid laden macrophages. Current medical therapies for the prevention of atherosclerotic therapies enable the elucidation of mechanisms linking platelets to inflammation and atherosclerosis.

HspB8 expression in brain tissue after cerebral ischemic reperfusion and atorvastatin intervention in Sprague-Dawley rats

OBJECTIVE

The aim of this study was to evaluate the expression of HspB8 in the brain cortex of Sprague-Dawley rats after cerebral ischemic reperfusion (I/R) and atorvastatin intervention. It also aimed to determine the possible mechanism of atorvastatin intervention. A model of cerebral I/R in Sprague-Dawley rats was used.

METHODS

Fifty-two male Sprague-Dawley rats were randomly divided into four groups. The normal and sham-operated groups received no treatment. The I/R group was intragastrically administered with physiological saline, and the intervention group received atorvastatin (10 mg/kg) prepared with physiological saline according to reperfusion time (time of palinesthesia, 24 and 48 hours). All rats were killed after 72 hours of reperfusion.

RESULTS

2,3,5-Triphenyltetrazolium chloride staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling showed that atorvastatin significantly reduced the volume of cerebral infarction (%) in the brain tissue and attenuated neuronal apoptosis in the cortex of rats, respectively. HspB8 was expressed in the pallium of Sprague-Dawley rats in the normal and sham-operated groups. The expression level of HspB8 was significantly upregulated after cerebral I/R. However, the level of HspB8 expressed was lower in the intervention group than in the I/R group.

CONCLUSION

The expression of HspB8 was upregulated after cerebral I/R injury. Atorvastatin affected the precursors of the heat shock stress response, relieved stress injury due to cerebral ischemia, downregulated HspB8 expression, and inhibited nerve cell apoptosis in the brain cortex. However, HspB8 might not contribute to atorvastatin-mediated cytoprotective effects.

Does enhancement of oxidative stress markers mediate health effects of ambient air particles?

Evidence indicates that oxidative stress generation may contribute to health effects associated with particulate matter (PM) exposure. We investigated oxidative stress markers in 113 workers exposed to metal-rich PM and 61 nonexposed comparable volunteers. The plasma levels of soluble NOX2-derived peptide (sNOX2-dp) and two oxidative stress markers, urinary 8-hydroxydeoxyguanosine (8-OHdG) and 8-iso-prostaglandinF2alpha (8-iso-PGF2α), were analyzed. The plasma levels of the antioxidant alpha-tocopherol were also evaluated. The workers' average exposure to PM with an aerodynamic diameter <10 μm (PM₁₀) was much higher at the workplace than in the city, where the volunteers lived. Workers had significantly higher urinary 8-iso-PGF2α and 8-OHdG and plasma sNOX2-dp levels than nonexposed subjects. Alpha-tocopherol was much lower in workers compared with nonexposed subjects. In multivariable regression models adjusted for age, body mass index, and smoking, 8-iso-PGF2α increased in workers in association with PM10 and metal exposure; 8-OHdG and sNOX2-dp were associated only with iron. Alpha-tocopherol was inversely associated with each of the oxidative stress markers. Our observation leads to the hypothesis that the enhancement of oxidative stress markers associated with exposure to high metal-rich PM levels represents a possible step in the pathways leading from particle exposure to systemic (e.g., cardiovascular) effects.

Different degrees of NADPH oxidase 2 regulation and in vivo platelet activation: lesson from chronic granulomatous disease

Background

In vitro study showed that NADPH oxidase (NOx), the most important enzyme producing reactive oxygen species (ROS), plays a role in the process of platelet activation. However, it is unclear if changes in its activity affect platelet activation in vivo.

Methods and Results

In vivo and ex vivo experiments assessing platelet activation were investigated in healthy subjects, obese patients, and subjects with different low rates of NOx2 activity, namely X‐linked chronic granulomatous disease (X‐CGD) patients and X‐CGD carriers. We included 27 X‐CGD patients, 31 women carriers of hereditary deficiency of NOx2, 31 obese women, and 62 healthy subjects matched for sex and age. Plasma levels of soluble sCD40 L (sCD40L) and soluble P (sP)‐selectin, 2 markers of in vivo platelet activation, were reduced in X‐CGD patients (sCD40L=−55%; sP‐selectin=−51%, P<0.001) and in X‐CGD carriers (sCD40L=−41%; sP‐selectin=−57%, P<0.001) compared with respective controls. Conversely, obese women, who disclosed NOx2 upregulation, had significantly higher plasma levels of sCD40L (+47%, P<0.001) and sP‐selectin (+70%, P<0.001) compared with controls. Ex vivo study showed platelet isoprostane downexpression and enhanced platelet NO generation in both X‐CGD patients and X‐CGD carriers compared with controls; opposite findings were observed in obese patients. Correlation analysis showed that platelet NOx2 regulation was directly associated with plasma levels of sCD40L (R=0.336, P<0.001) and sP‐selectin (R=0.441; P<0.001).

Conclusions

The study provides the first evidence that in vivo platelet activation is significantly and directly associated with NOx2 activity. Platelet NOx2 may be a novel target for platelet activation inhibition.

Statin therapy is associated with reduced incidence of hypoxic hepatitis in critically ill patients

BACKGROUND & AIMS

Hypoxic hepatitis (HH) is a frequent and life-threatening complication associated with states of oxygen depletion in critically ill patients. Ischemia and reperfusion contribute to liver injury in HH. Experimental data suggest beneficial effects of statins in hepatic ischemia/reperfusion injury. This study was conducted to investigate whether statin treatment prior to intensive care unit (ICU) admission affects incidence rates and severity of HH.

METHODS

Eight hundred fifty-one patients admitted consecutively to three medical ICUs between December 2008 and December 2009 were prospectively screened for new occurrence of HH within 48 h following ICU admission. Statin treatment prior to ICU admission was assessed. 28-day-, 90-day-, and 1-year-survival as well as new-onset of complications in HH patients were prospectively documented.

RESULTS

Eighty-seven patients (10%) developed HH. Statin treatment prior to ICU admission was significantly associated with decreased incidence of HH within 48 h after ICU admission in the multivariate analysis (adjusted OR=0.42 (95% CI 0.19-0.95); p<0.05). Cardiogenic shock (p<0.001), septic shock (p<0.001) and active alcohol consumption (p<0.01) were identified as independent risk factors for development of HH. 28-day-, 90-day-, and 1-year-mortality rates in HH were 58%, 67%, and 74%, respectively. Statins were associated with improved 28-day-survival in the total study cohort (p<0.05), but did not affect 90-day- and 1-year-mortality, respectively.

CONCLUSIONS

Cardiogenic shock, septic shock, and active alcohol consumption were independent factors predisposing patients to new onset of HH. Statin treatment prior to ICU admission was the only protective factor regarding the new occurrence of HH in critically ill patients.

Dietary modulators of statin efficacy in cardiovascular disease and cognition

Cardiovascular disease remains the leading cause of morbidity and mortality in the United States and other developed countries, and is fast growing in developing countries, particularly as life expectancy in all parts of the world increases. Current recommendations for the prevention of cardiovascular disease issued jointly from the American Academy of Cardiology and American Heart Association emphasize that lifestyle modification should be incorporated into any treatment plan, including those on statin drugs. However, there is a dearth of data on the interaction between diet and statins with respect to additive, complementary or antagonistic effects. This review collates the available data on the interaction of statins and dietary patterns, cognition, genetics and individual nutrients, including vitamin D, niacin, omega-3 fatty acids, fiber, phytochemicals (polyphenols and stanols) and alcohol. Of note, although the available data is summarized, the scope is limited, conflicting and disparate. In some cases it is likely there is unrecognized synergism. Virtually no data are available describing the interactions of statins with dietary components or dietary pattern in subgroups of the population, particularly those who may benefit most were positive effects identified. Hence, it is virtually impossible to draw any firm conclusions at this time. Nevertheless, this area is important because were the effects of statins and diet additive or synergistic harnessing the effect could potentially lead to the use of a lower intensity statin or dose.

Statins as regulators of redox signaling in platelets

SIGNIFICANCE

Reactive oxidant species (ROS) are highly reactive molecules produced by several cell lines including platelets and serve as second messenger for intracellular signaling. In recent years it became evident that ROS are also implicated in the thrombotic process. Statins are lipid lowering molecules which reduce serum cholesterol and retard atherosclerotic complication and its clinical sequelae. However there is evidence that statins may exert an antiplatelet effects by interfering with redox signaling.

RECENT ADVANCES

Experimental and clinical studies provided evidence that intra-platelet ROS formation is implicated in the process of thrombosis, as impaired ROS neutralization is associated with serious thrombotic complication and eventually death. Recent studies demonstrated that statins possess antiplatelet activity via inhibition of platelet NADPH oxidase-derived ROS formation. This effect results in down-regulation of isoprostanes, which are pro-aggregating molecules, and up-regulation of nitric oxide, which is a platelet inhibitor; such changes occurred immediately after statin's administration and were independent from lipid lowering property.

CRITICAL ISSUES

Experimental and clinical studies documented that statins possess an antithrombotic effects which may account for thrombotic-related vascular outcomes. This has been evidenced in clinical settings such as percutaneous coronary intervention, myocardial infarction and venous thrombosis. It is still unclear, however, if the statin's antithrombotic effect is dose-related.

FUTURE DIRECTIONS

Future studies should be addressed to analyze if the antiplatelet effect of statins may preferentially occur at high dosage of statins. Furthermore, the antiplatelet effects of statins could turn useful in clinical settings where the clinical efficacy of aspirin and other antiplatelet drugs are still uncertain.

Platelet NOX, a novel target for anti-thrombotic treatment

There is a growing body of evidence to suggest that reactive oxidant species (ROS) including O2-, OH- or H2O2 act as second messengers to activate platelets via 1) calcium mobilisation, 2) nitric oxide (NO) inactivation, and 3) interaction with arachidonic to give formation of isoprostanes. Among the enzymes generating ROS formation NOX2, the catalytic core of NADPH oxidase (NOX), plays a prominent role as shown by the almost absent ROS production by platelets taken from patients with hereditary deficiency of NOX2. Experimental and clinical studies provided evidence that NOX2 is implicated in platelet activation. Thus, impaired platelet activation has been detected in patients with NOX2 hereditary deficiency. Similarly, normal platelets added with NOX2 specific inhibitors disclosed impaired platelet activation along with ROS down-regulation. Accordingly, animals prone to atherosclerosis treated with apocynin, a NOX inhibitor, showed reduced platelet adhesion and atherosclerotic plaque. Furthermore, a significant association between NOX2 up-regulation and platelet activation has been detected in patients at athero-thrombotic risk, but a cause-effect relationship needs to be established. These findings may represent a rationale to plan interventional trials with NOX inhibitors to establish if blocking NOX2 or other NOX isoforms may represent a novel anti-platelet approach.

Antioxidant and antiplatelet effects of atorvastatin by Nox2 inhibition

In recent years, it became evident that reactive oxygen species (ROS) are implicated in the thrombotic process. Statins are lipid-lowering agents able to lower serum cholesterol levels and retard atherosclerotic complications and their clinical sequelae. There is evidence that, among statins, atorvastatin may exert antiplatelet effects by interfering with redox signaling. Recent studies demonstrated that atorvastatin possesses antiplatelet activity via inhibition of platelet formation of NADPH oxidase-derived ROS. This effect results in down-regulation of isoprostanes, which are pro-aggregating molecules, and up-regulation of nitric oxide, which is a platelet inhibitor; such changes occurred immediately after atorvastatin administration and were independent from lipid-lowering property. Experimental and clinical studies documented that statins possess antithrombotic effects, which may account for the reduction of thrombotic-related vascular outcomes. This has been evidenced in different cardiovascular clinical settings such as percutaneous coronary intervention (PCI), myocardial infarction (MI), and venous thrombosis. Future studies should be addressed to analyze if the antiplatelet effect of atorvastatin may preferentially occur at high dosage. Interestingly, the antiplatelet effects of statins could be useful in clinical settings where the clinical efficacy of aspirin and other antiplatelet drugs is still uncertain.

Antithrombotic actions of statins involve PECAM-1 signaling

Statins are widely prescribed cholesterol-lowering drugs that are a first-line treatment of coronary artery disease and atherosclerosis, reducing the incidence of thrombotic events such as myocardial infarction and stroke. Statins have been shown to reduce platelet activation, although the mechanism(s) through which this occurs is unclear. Because several of the characteristic effects of statins on platelets are shared with those elicited by the inhibitory platelet adhesion receptor PECAM-1 (platelet endothelial cell adhesion molecule-1), we investigated a potential connection between the influence of statins on platelet function and PECAM-1 signaling. Statins were found to inhibit a range of platelet functional responses and thrombus formation in vitro and in vivo. Notably, these effects of statins on platelet function in vitro and in vivo were diminished in PECAM-1(-/-) platelets. Activation of PECAM-1 signaling results in its tyrosine phosphorylation, the recruitment and activation of tyrosine phosphatase SHP-2, the subsequent binding of phosphoinositol 3-kinase (PI3K), and diminished PI3K signaling. Statins resulted in the stimulation of these events, leading to the inhibition of Akt activation. Together, these data provide evidence for a fundamental role of PECAM-1 in the inhibitory effects of statins on platelet activation, which may explain some of the pleiotropic actions of these drugs.

The effects of atorvastatin on oxidative stress in L-NAME-treated rats

OBJECTIVES

Current evidence suggests that the beneficial vascular effects of statins are not limited to the statins' lipid-lowering properties; these drugs can also improve vascular endothelial cell function. Nω-nitro-l-arginine methyl ester (L-NAME) is a potent synthetic nitric oxide inhibitor, and long-term oral L-NAME treatment is used to induce vascular lesions in experimental animal models.

METHODS

We determined the effects of statins on protein carbonyl (PCO), lipid hydroperoxides (LHP), oxidized low-density lipoproteins (ox-LDL) and antioxidants such as paraoxonase 1 (PON1) and total thiols (T-SH) in long-term L-NAME-treated rats. Adult male Wistar rats were divided into three groups, namely, control, L-NAME-treated (1 mg/mL in drinking water for three weeks), and atorvastatin plus L-NAME-treated (4 mg/kg/day atorvastatin for 1 week during the third week of L-NAME treatment) groups.

RESULTS

In the L-NAME group, the ox-LDL, LHP and PCO were higher and the PON1 and T-SH were lower than the concentrations observed for the controls. When compared with the L-NAME group, the L-NAME plus atorvastatin group had significantly lower ox-LDL and LHP and higher PON1 activities. Additionally, the elevated total cholesterol (TC) and low-density lipoprotein-C (LDL-C) in the L-NAME group were decreased by atorvastatin administration. TC and LDL-C were positively correlated with ox-LDL and LHP and negatively correlated with PON1 in all groups. High-density lipoprotein-C (HDL-C) was negatively correlated with ox-LDL.

CONCLUSION

PON1 prevents LDL oxidation and inactivates LDL-derived oxidized phospholipids; its activity showed a pronounced decrease in the L-NAME treatment group and was increased in the atorvastatin group. Based on our findings, we concluded that the atorvastatin had HDL-related antioxidant activity as well as lipid-lowering properties.

Patients with microvascular obstruction after primary percutaneous coronary intervention show a gp91phox (NOX2) mediated persistent oxidative stress after reperfusion

BACKGROUND

Persistent oxidative stress may play a key role in microvascular obstruction (MVO). We aimed at assessing the role of platelet gp91phox (NOX2), the catalytic subunit of NADPH oxidase in MVO.

METHODS

We enrolled 40 patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention within 12 h from symptoms onset, either with angiographic MVO (n=20) or good angiographic myocardial reperfusion (MR) (n=20). Angiographic MVO was defined as a final thrombolysis in myocardial infarction (TIMI) flow ≤2 or TIMI flow of 3 with myocardial blush grade <2. NOX2 and isoprostanes (8-iso-PGF2α) levels, as assessed by enzyme-linked immunoadsorbent assay (ELISA) or by an enzyme immunoassays, respectively, were measured on admission, at 24 h and pre-discharge.

RESULTS

NOX2 levels increased from baseline to pre-discharge in patients with angiographic MVO (20.25 (15-24.75) pg/ml vs 25.50 (17-29.25) pg/ml, p=0.02), but not in MR patients (p=0.45), with a significant interaction between baseline and pre-discharge levels among the two groups (p=0.04). The levels of 8-iso-PGF2α showed a trend to increase from baseline to pre-discharge in angiographic MVO patients (295 (183.50-389.25) pmol/l vs 322 (206-370) pmol/l, p=0.06), but not in patients with MR (p=0.56), with a trend for interaction between baseline and pre-discharge levels among the two groups (p=0.09).

CONCLUSION

Patients with MVO, but not those with myocardial reperfusion, have a sustained increase of NOX2 and 8-iso-PGF2α. Therapies targeting NOX2 or high dosage antioxidants should be tested for MVO prevention and treatment.

Effect of atorvastatin on hematologic parameters in patients with hypercholesterolemia

Hematologic parameters such as mean platelet volume (MPV), red cell distribution width (RDW), and neutrophil to lymphocyte (N/L) ratio are associated with increased cardiovascular risk. We investigated the effect of atorvastatin on hematologic parameters in patients with hypercholesterolemia. A total of 79 patients with hypercholesterolemia and 47 normocholesterolemic healthy participants were included. Patients with hypercholesterolemia received 10 to 80 mg/d atorvastatin during a 24-week period. Hematologic parameters were measured at baseline and after 6 months. Atorvastatin treatment produced a significant decrease in MPV levels (9.3 ± 1.3 vs 9.1 ± 1.2 fL, P = .008) and platelet count (259 ± 61 vs 248 ± 51 10(9)/L, P = .005). The N/L ratio decreased significantly after atorvastatin treatment from 2.9 ± 1.2 to 2.6 ± 1.1, (P = .014). The RDW and platelet distribution width levels were not different among the study groups, before and after treatment. Atorvastatin may beneficially reduce MPV levels and N/L ratio. This antiplatelet and anti-inflammatory effect of atorvastatin treatment could play a role in reducing cardiovascular risk.

Rosuvastatin reduces platelet recruitment by inhibiting NADPH oxidase activation

Rosuvastatin increased vascular endothelial NO and attenuated platelet activation after ischemia-reperfusion in mice; nevertheless, the influence of rosuvastatin on the activation of human platelets and the underlying mechanism has never been investigated. In an in vitro study platelets from 8 healthy donors were incubated with scalar concentrations of rosuvastatin (1-10 μM) before activation. Platelet recruitment (PR), that mimics the propagation of platelet aggregation and is dependent upon isoprostane formation, was investigated. PR was inhibited by rosuvastatin in concentration-dependent manner concomitantly with down-regulation of platelet release of the pro-thrombotic molecule CD40L. This effect was associated with lower production of platelet reactive oxygen species (ROS), isoprostane and activation of the glycoprotein IIb/IIIa and was counteracted by exogenous addition of isoprostanes. Conversely, rosuvastatin concentration-dependently increased platelet NO. Platelet isoprostane formation mainly depends from NADPH oxidase. Rosuvastatin concentration-dependently inhibited platelet sNOX2-dp release, a specific marker of NADPH oxidase activation, PKC phosphorylation and p47(phox) translocation from cytosol to membranes. In an ex vivo study 10 hypercolesterolemic patients were randomly allocated to diet or rosuvastatin (20 mg). We observed that as early as 2h after rosuvastatin PR, platelet isoprostanes formation, platelet CD40L and sNOX2-dp decreased while platelet NO increased; no changes were detected in diet-assigned patients. This study shows that in vitro rosuvastatin impairs platelet activation via inhibition of NOX2-derived oxidative stress. This effect, which is associated ex vivo with acute inhibition of platelet activation, suggests that rosuvastatin behaves as an antiplatelet drug.