Partial inhibition of nitric oxide synthase primes the stimulated pathway of vWF-secretion in man

Impact of von Willebrand factor on coronary plaque burden in coronary artery disease patients treated with statins

High von Willebrand factor (VWF) levels have been reported to be associated with an increased risk of cardiovascular events. However, the relationship between VWF levels and coronary atherosclerosis in patients with coronary artery disease (CAD) who have already received stain treatment is still unclear. We examined the association between VWF levels and coronary plaque as assessed by intravascular ultrasound (IVUS) in CAD patients treated with statins. Ninety-one CAD patients who underwent percutaneous coronary intervention under IVUS guidance, and who were already receiving statin treatment based on Japanese guidelines, were included. An IVUS examination was performed for the culprit lesion, and plasma VWF antigen levels were measured using enzyme-linked immuno sorbent assay. In all of the patients, the low-density lipoprotein cholesterol levels just before the IVUS examination were low (86 ± 26 mg/dL). The VWF levels were positively correlated with the plaque burden expressed as percent atheroma volume (PAV) (r = 0.39, P = .001), while there was no significant association between VWF and plaque composition. Multivariate stepwise regression analysis showed that higher VWF levels were independently associated with increased PAV (β=0.26, P = .01). In CAD patients who had already been treated with statins, higher VWF levels were associated with a higher coronary plaque burden, suggesting that a high VWF level may be a marker of the residual cardiovascular risk after statin treatment.

Von Willebrand factor and the right ventricle (the MESA-Right Ventricle Study)

Elevation in plasma activity of von Willebrand factor (vWF) reflects endothelial dysfunction and predicts death in pulmonary arterial hypertension. Higher vWF activity is also associated with a lower right ventricular (RV) ejection fraction in pulmonary arterial hypertension. Little is known about the relation between vWF and RV structure and function in adults without cardiovascular disease. The present investigation included 1,976 participants with magnetic resonance imaging assessment of RV structure and function and measurement of vWF activity from the Multi-Ethnic Study of Atherosclerosis. Multivariable linear regression was used to estimate the associations between vWF activity and measures of RV structure and function after adjusting for demographics, anthropometrics, smoking, diabetes mellitus, hypertension, and the corresponding left ventricular parameter. The average vWF activity was 140.7 ± 57.2%. Elevated vWF activity was independently associated with lower RV mass, RV end-diastolic volume, and RV stroke volume in models with and without adjustment for the corresponding left ventricular parameter (all p values <0.05). There was no association observed between vWF activity and the RV ejection fraction. In conclusion, higher vWF activity is associated with lower RV mass, RV end-diastolic volume, and RV stroke volume. These associations are independent of common cardiovascular risk factors and left ventricular morphologic changes.

von Willebrand factor inhibition improves endothelial function in patients with stable angina

ALX-0081 is a novel nano-antibody inhibiting von Willebrand factor (vWF). We evaluated whether direct inhibition of vWF by ALX-0081 improves endothelial function. Stable patients (pts, n = 55) with single vessel disease undergoing percutaneous coronary intervention (PCI) were randomized to ALX-0081 (n = 38) or placebo (n = 17). vWF inhibition was assessed by vWF antigen level (vWF:Ag) and activity by ristocetin test (vWF:RiCo). Endothelial function was assessed before (BL), 6 h and 24 h after PCI by: (a) endothelial peripheral arterial tonometry (Endoscore); (b) endothelial microparticles (EMPs) by flow cytometry. vWF:Ag and vWF:RiCo decreased within 1 h from ALX-0081. In the placebo group, no significant Endoscore changes occurred from BL to 24 h. In ALX-0081 group, Endoscore increased from BL to 24 h (p = 0.014). A decrease in EMPs was observed after ALX-0081 (p < 0.01), while no changes occurred in placebo pts. An inhibition of vWF with ALX-0081 significantly improves peripheral endothelial function.

Von Willebrand factor and oxidative stress parameters in acute coronary syndromes

Considering the role of von Willebrand factor (vWf) in hemostasis, and the role of oxidative stress in the development of endothelial dysfunction and atherosclerotic disease, the aim of our study was to investigate the relationship between vWf, parameters of oxidative stress and different types of acute coronary syndromes (ACS). Levels of vWf activity (vWfAct), vWf antigen (vWfAg), nitric oxide (estimated through nitrites–NO₂  ⁻), superoxide anion radical (O₂  ⁻), hydrogen peroxide (H₂O₂), index of lipid peroxidation (estimated through thiobarbituric acid reactive substances–TBARS), superoxide dismutase (SOD) and catalase (CAT) activity of 115 patients were compared with those of 40 healthy controls. ACS patients had significantly higher vWfAct and vWfAg levels, as well as TBARS levels, while their levels of NO₂  ⁻, H₂O₂, SOD and CAT activities were lower than controls'. vWfAg showed high specificity and sensitivity as a test to reveal healthy or diseased subjects. Multivariant logistic regression marked only vWfAg and TBARS as parameters that were under independent effect of ACS type. The results of our study support the implementation of vWf in clinical rutine and into therapeutic targets, and suggest that ACS patients are in need of antioxidant supplementation to improve their impaired antioxidant defence.

Neutrophil-Lymphocyte Ratio Predicts Medium-Term Survival Following Elective Major Vascular Surgery: A Cross-Sectional Study

Background: The systemic nature of atherosclerosis compromises medium-term survival following major vascular surgery. Neutrophil—lymphocyte ratio (NLR) is a simple index of systemic inflammatory burden which correlates with survival following percutaneous coronary intervention. Methods: Patients undergoing elective major vascular surgery in 2 tertiary vascular units were identified from prospectively maintained databases. Factors associated with 2-year mortality were assessed by univariate and multivariate analyses. Results: Over a 4-year period, 1021 patients underwent elective major vascular surgery (carotid endarterectomy, abdominal aortic aneurysm repair, lower limb revascularization). Two-year mortality was 11.2%. In multivariate analysis, preoperative NLR > 5 was independently associated with 2-year mortality (multivariate odds ratio [OR] 2.21; 95% confidence interval [CI] 1.22-4.01). Conclusion: Preoperative NLR identifies patients at increased risk of death within 2 years of major vascular surgery. This simple index may facilitate targeted preventive measures for high-risk patients.

Increased endothelial exocytosis and generation of endothelin-1 contributes to constriction of aged arteries

RATIONALE

Circulating levels of endothelin (ET)-1 and endogenous ET(A)-mediated constriction are increased in human aging. The mechanisms responsible are not known.

OBJECTIVE

Investigate the storage, release, and activity of ET-1 system in arteries from young and aged Fischer-344 rats.

METHODS AND RESULTS

After NO synthase inhibition (L-NAME), thrombin contracted aged arteries, which was inhibited by endothelial denudation, ET(A) receptor antagonism (BQ123), and ECE inhibition (phosphoramidon, SM19712) or by inhibiting exocytosis (TAT-NSF, N-ethylmaleimide-sensitive factor inhibitor). Thrombin did not cause endothelium-dependent contraction of young arteries. In aged but not young arteries, thrombin rapidly increased ET-1 release, which was abolished by endothelium denudation or TAT-NSF. L-NAME did not affect ET-1 release. ET-1 immunofluorescent staining was punctate and distinct from von Willebrand factor (VWF). VWF and ET-1 immunofluorescent intensity was similar in young and aged quiescent arteries. Thrombin rapidly increased ET-1 staining and decreased VWF staining in aged but had no effect in young aortas. After L-NAME, thrombin decreased VWF staining in young aortas. NO donor DEA-NONOate (1 to 100 nmol/L) reversed thrombin-induced exocytosis in young (VWF) but not aged L-NAME-treated aortas (VWF, ET-1). Expression of preproET-1 mRNA and ECE-1 mRNA were increased in aged compared to young endothelium. BigET-1 levels and contraction to exogenous BigET-1 (but not ET-1) were also increased in aged compared to young arteries.

CONCLUSIONS

The stimulated exocytotic release of ET-1 is dramatically increased in aged endothelium. This reflects increased reactivity of exocytosis, increased expression and storage of ET-1 precursor peptides, and increased expression of ECE-1. Altered endothelial exocytosis of ET-1 and other mediators may contribute to cardiovascular pathology in aging.

Pronounced platelet hyperfunction in patients with cardiac arrest achieving restoration of spontaneous circulation

OBJECTIVE

Markers of platelet activation are increased in patients undergoing cardiopulmonary resuscitation. Hyperfunctional platelets may contribute to impairment of microcirculatory function and overall poor outcome despite restoration of spontaneous circulation (ROSC). Patients with myocardial infarction have hyperfunctional platelets, which predict the degree of myocardial necrosis. Thus, we hypothesized that platelets may be even more activated in patients whose myocardial infarction leads to cardiac arrest and compared them with patients whose cardiac arrest was due to a noncardiac origin.

DESIGN

Prospective observational study.

SETTING

Emergency department of a tertiary care hospital.

PATIENTS

One hundred four patients with witnessed cardiac arrest who achieved ROSC.

INTERVENTIONS

Blood sampling.

MEASUREMENTS AND MAIN RESULTS

We assessed collagen adenosine diphosphate closure time with the platelet function analyzer-100, and measured plasma levels of von Willebrand factor: ristocetin cofactor activity levels by turbidometry. Independent physicians diagnosed the origin of cardiac arrest. The majority of cardiac arrests were caused by myocardial ischemia. Invariably, collagen adenosine diphosphate closure time values (55 seconds; 95% confidence interval: 52-58 seconds) were much shorter in these patients compared with patients with other causes of cardiac arrest (110 seconds; 95% confidence interval: 84-135 seconds, p < 0.001). von Willebrand factor: ristocetin cofactor activity plasma levels were more than three-fold above normal values in both groups.

CONCLUSIONS

Patients with myocardial ischemia-triggered cardiac arrest had the highest degree of platelet hyperfunction under high shear rates, which was not solely due to increased von Willebrand factor. Future trials are necessary to clarify whether rapid, more aggressive antiplatelet therapy improves outcome after cardiac arrest.

von Willebrand factor in cardiovascular disease: focus on acute coronary syndromes

von Willebrand factor (VWF) plays a pivotal role in platelet adhesion and aggregation at sites of high shear rates (eg, in coronary arteries that have stenotic or ruptured atherosclerotic plaque lesions). Numerous studies have investigated the relationship between VWF plasma levels and thromboembolic cardiovascular events. In contrast to the rather weak association in the general population, in patients with preexisting vascular disease, VWF is significantly predictive for adverse cardiac events, including death. Likewise, VWF typically rises during the course of acute coronary syndrome, and the extent of this VWF release is an independent predictor of adverse clinical outcome in these patients. Various lines of evidence indicate that VWF is not only a marker but also actually an important effector in the pathogenesis of myocardial infarction. This central role of VWF in thrombogenesis has made it a promising target for research into new antiplatelet therapies that specifically inhibit VWF. This review focuses on the role of VWF in acute coronary syndrome and further outlines the relevance of therapeutic interventions targeting VWF for acute coronary syndrome patients.

Neuropeptide Y-induced acceleration of postangioplasty occlusion of rat carotid artery

OBJECTIVE

Attempts to restore blood flow through atherosclerotic vessels by angioplasty often result in restenosis. Because the role of nerves in this process is unclear, we investigated whether neuropeptide Y (NPY), a sympathetic cotransmitter with vascular mitogenic activities, contributes to postangioplasty restenosis.

METHODS AND RESULTS

Carotid artery balloon angioplasty upregulated vascular expression of NPY and its processing enzyme (DPPIV/cd26) and receptors (Y1, Y2, Y5 mRNA and protein) within 6 to 24 hours and stimulated neointima formation and accumulation of NPY in platelets after 14 days. NPY pellets (1 to 10 microg/pellet for 14 days) inserted next to the injured artery elevated platelet and vascular NPY immunoreactivity to stress-like levels and dose-dependently augmented angioplasty-induced neointima. Strikingly, 10 microg NPY for 14 days led to vessel occlusion with an atherosclerotic-like lesion, with thrombus and neointima containing neovessels, macrophages, matrix, and lipids. Y1 or Y5 receptor antagonist completely prevented the effect of NPY and reduced angioplasty-induced neointima by 50%.

CONCLUSIONS

Angioplasty upregulates platelet and vascular NPY systems, which then contribute to neointima formation via Y1 and Y5 receptor activation. Increasing NPY to high stress levels triggers formation of a thrombotic atherosclerotic-like lesion and vessel occlusion. Thus, NPY may be a risk factor for accelerated atherosclerosis, and NPY receptor antagonists may be a possible new treatment for restenosis.

Pharmacological characteristics of solid-phase von Willebrand factor in human platelets

1. The pharmacological characteristics of solid-phase von Willebrand factor (svWF), a novel platelet agonist, were studied. 2. Washed platelet suspensions were obtained from human blood and the effects of svWF on platelets were measured using aggregometry, phase-contrast microscopy, flow cytometry and zymography. 3. Incubation of platelets with svWF (0.2 - 1.2 microg ml(-1)) resulted in their adhesion to the ligand, while co-incubations of svWF with subthreshold concentrations of ADP, collagen and thrombin resulted in aggregation. 4. 6B4 inhibitory anti-glycoprotein (GP)Ib antibodies abolished platelet adhesion stimulated by svWF, while aggregation was reduced in the presence of 6B4 and N-Acetyl-Pen-Arg-Gly-Asp-Cys, an antagonist of GPIIb/IIIa. 5. Platelet adhesion stimulated with svWF was associated with a concentration-dependent increase in expression of GPIb, but not of GPIIb/IIIa. 6. In contrast, collagen (0.5 - 10.0 microg ml(-1)) caused down-regulation of GPIb and up-regulation of GPIIb/IIIa in platelets. 7. Solid-phase vWF (1.2 microg ml(-1)) resulted in the release of MMP-2 from platelets. 8. Inhibition of MMP-2 with phenanthroline (10 microM), but not with aspirin or apyrase, inhibited platelet adhesion stimulated with svWF. 9. In contrast, human recombinant MMP-2 potentiated both the effects of svWF on adhesion and up-regulation of GPIb. 10. Platelet adhesion and aggregation stimulated with svWF were reduced by S-nitroso-n-acetyl-penicillamine, an NO donor, and prostacyclin. 11. Thus, stimulation of human platelets with svWF leads to adhesion and aggregation that are mediated via activation of GPIb and GPIIb/IIIa, respectively. 12. Mechanisms of activation of GPIb by svWF involve the release of MMP-2, and are regulated by NO and prostacyclin.

Estrogen and cerebrovascular physiology and pathophysiology

Numerous studies have uncovered a wide variety of estrogen effects with apparent cardiovascular benefits, the most recognized ones being vasodilation, anti-atherogenesis, diminished post-ischemic inflammation and anti-oxidant effects. This article provides an overview of the influence of estrogen on the cerebral vasculature, under physiologic and pathophysiologic conditions, and covers both acute and chronic effects. The discussion is primarily focused on the vasodilatory and anti-inflammatory actions of estrogen, since those particular estrogen influences have received the greatest attention in studies published to date. With respect to vasodilation, although some consideration is given to the role of other vasodilating mechanisms and factors, the emphasis is mostly placed on the endothelial isoform of nitric oxide synthase, eNOS, which has emerged as a clear target of estrogen. Some consideration is given to recent findings that suggest that estrogen can stimulate eNOS activity by decreasing the expression of the eNOS inhibitor caveolin-1. With regard to the ability of estrogen to counteract inflammation, potential mechanisms by which estrogen limits the post-ischemic leukocyte adhesion, and the expression of the inducible NOS, are discussed.