Inter-relationships of indices of endothelial damage/dysfunction [circulating endothelial cells, von Willebrand factor and flow-mediated dilatation] to tissue factor and interleukin-6 in acute coronary syndromes

Identifying the Role of Flow-Mediated Dilatation Assessment in Acute Coronary Syndromes: A Systematic Review

In the context of the global burden of cardiovascular disease, the development of novel, patient-targeted diagnostic and therapeutic strategies is of paramount importance. Acute coronary syndromes (ACS) comprise a subset of cardiovascular disease, with constantly increasing prevalence requiring urgent attention. Flow-mediated dilatation (FMD), a noninvasive method for the evaluation of endothelial function, has been previously implemented in patients with ACS. A systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was conducted in order to identify all relevant studies assessing the implementation of FMD among patients with ACS. Our review reflects an effort to present all available data regarding the role of FMD to date, a valuable noninvasive and easy accessible diagnostic tool, in the prognosis of patients with ACS. FMD evaluation in patients with ACS reveals a decline in values, indicative of the presence of endothelial function among this distinct patient group. FMD has also been used to assess the response to various treatments, as well as to predict major adverse cardiovascular events. Dynamic responses to interventions highlights its potential in the evolving field of interventional cardiology.

Research progress on the molecular mechanism of coronary microvascular endothelial cell dysfunction

Coronary microvascular disease is a high-risk factor for many cardiovascular events. However, due to its high concealment and many etiologies, the current understanding of its pathophysiological mechanism is very limited, which greatly limits its clinical diagnosis and treatment. In the process of the occurrence and development of coronary microvascular disease, the damage of coronary microvascular endothelial cell (CMEC) is the core link. CMEC's stress, metabolism, inflammation and other dysfunctions have a causal relationship with coronary microvascular disease, and are also the main features of coronary microvascular disease in the early stage. This article mainly reviews the molecular mechanisms of CMEC damage.

The systemic microcirculation in dialysis populations

In a rapidly expanding population of patients with chronic kidney disease, including 2 million people requiring renal replacement therapy, cardiovascular mortality is 15 times greater than the general population. In addition to traditional cardiovascular risk factors, more poorly defined risks related to uremia and its treatments appear to contribute to this exaggerated risk. In this context, the microcirculation may play an important early role in cardiovascular disease associated with chronic kidney disease. Experimentally, the uremic environment and dialysis have been linked to multiple pathways causing microvascular dysfunction. Coronary microvascular dysfunction is reflected in remote and more easily studied vascular beds such as the skin. There is increasing evidence for a correlation between systemic microvascular dysfunction and adverse cardiovascular outcomes. Systemic microcirculatory changes have not been extensively investigated across the spectrum of chronic kidney disease. Recent advances in non-invasive techniques studying the microcirculation in vivo in man are increasing the data available particularly in patients on hemodialysis. Here, we review current knowledge of the systemic microcirculation in dialysis populations, explore whether non-invasive techniques to study its function could be used to detect early stage cardiovascular disease, address challenges faced in studying this patient cohort and identify potential future avenues for research.

Coronary Artery Disease and Endothelial Dysfunction: Novel Diagnostic and Therapeutic Approaches

Coronary artery disease is the leading cause of morbidity and mortality worldwide. The most common pathophysiologic substrate is atherosclerosis which is an inflammatory procedure that starts at childhood and develops throughout life. Endothelial dysfunction is associated with the initiation and progression of atherosclerosis and is characterized by the impaired production of nitric oxide. In general, endothelial dysfunction is linked to poor cardiovascular prognosis and different methods, both invasive and non-invasive, have been developed for its evaluation. Ultrasound evaluation of flow mediated dilatation of the branchial artery is the most commonly used method to assessed endothelial function while intracoronary administration of vasoactive agents may be also be used to test directly endothelial properties of the coronary vasculature. Endothelial dysfunction has also been the subject of therapeutic interventions. This review article summarizes the knowledge about evaluation of endothelial function in acute coronary syndromes and stable coronary artery disease and demonstrates the current therapeutic approaches against endothelial dysfunction.

Effect of interleukin-6 inhibition on coronary microvascular and endothelial function in myocardial infarction

OBJECTIVE

Interleukin-6 (IL-6) is a driver of inflammation and associated endothelial cell activation in acute coronary syndromes. We evaluated the effect of the IL-6 receptor antagonist tocilizumab on coronary microvascular function and endothelial dysfunction measured by coronary flow reserve (CFR) and markers of endothelial cell activation in patients with non-ST-elevation myocardial infarction (NSTEMI).

METHODS

This substudy was part of a two-centre, double-blind, randomised, placebo-controlled trial evaluating the effect of a single dose of tocilizumab in NSTEMI. Markers of endothelial cell activation (vascular cell adhesion molecule (VCAM)-1, intercellular adhesion molecule-1 and von Willebrand factor) were assessed in 117 patients. In 42 of these patients, 20 assigned to placebo and 22 to tocilizumab, we measured CFR. Blood samples were obtained at seven consecutive time points between day 1 and 3. CFR was measured by transthoracic echocardiography during hospitalisation and after 6 months.

RESULTS

Tocilizumab did not affect CFR during hospitalisation (tocilizumab: 3.4±0.8 vs placebo: 3.3±1.2, p=0.80). CFR improved significantly in both groups at 6 months. Patients in the tocilizumab group had significantly higher area under the curve for VCAM-1 (median 622 vs 609 ng/mL/hour, tocilizumab and placebo respectively, p=0.003). There were inverse correlations between VCAM-1 and CFR in the placebo (hospitalisation: r=-0.74, p<0.01, 6 months: r=-0.59, p<0.01), but not in the tocilizumab group (hospitalisation: r=0.20, p=0.37, 6 months r=-0.28, p=0.20).

CONCLUSIONS

Tocilizumab did not affect CFR during hospitalisation or after 6 months. Tocilizumab increased VCAM-1 levels during hospitalisation, but this was not associated with reduced CFR in these patients.

miRNA-1283 Regulates the PERK/ATF4 Pathway in Vascular Injury by Targeting ATF4

Background

In our previous study, we found significant differences in the mRNA and microRNA (miRNA) levels among hypertensive patients with different degrees of vascular endothelial cells damage. These differences were closely associated with endoplasmic reticulum stress (ERS)-related proteins. Moreover, compared to the control group, the expression of transcription factor activating factor 4 (ATF4) was also found to be significantly different in the hypertensive patients with different degrees of vascular endothelial cells damage groups. These results were confirmed using gene prediction software, which showed synergistic effects between ATF4 and miR-1283. ATF4 is a key molecule in ERS. Three ERS pathways exist:protein kinase RNA-like ER kinase (PERK), activating transcription factor 6 (ATF6) and inositol-requiring enzyme-1 (IRE-1)-induced apoptosis. The PERK pathway is the most important and also includes the phosphorylation of eukaryotic translation initiation factor 2α (eIF2α) and ATF4. In this report, we studied the regulatory effects of miR-1283 and ATF4 on the PERK-eIF2α-ATF4 signaling pathway using human umbilical vein endothelial cells (HUVECs) and mice.

Methodology/Principal Findings

We verified the relationship between miR-1283 and ATF4 using a luciferase activity assay and observed the regulatory effects of miR-1283 and ATF4 on the PERK-eIF2α-ATF4 signaling pathway in vivo and in vitro.

Conclusions/Significance

ATF4 is a target gene of miR-1283, which regulates the PERK-eIF2α-ATF4 signaling pathway by inhibiting ATF4, and it plays a critical role in inducing injury in HUVECs and mouse heart tissue.

Reproducibility of circulating endothelial cell enumeration and activation in children and adolescents

INTRODUCTION

We examined the reproducibility of circulating endothelial cells (CEC) enumeration and activation among youth.

MATERIALS AND METHODS

CECs from 151 youth were measured at baseline and 1 week follow-up. Enumeration of CEC in fresh whole blood was determined by direct assessment of buffy coat smears (CD146+ nucleated cells) and activated CEC (%VCAM-1 expression) was determined after immunomagnetic enrichment and co-staining of nuclei, plus positivity for P1H12 and VCAM-1.

RESULTS

No statistically significant difference in CEC enumeration (1.2 ± 2.5 vs 1.3 ± 2.2 CEC/milliliter of whole blood, p = 0.745) or activated CEC (57.1 ± 24.4 vs 58.0 ± 21.3 %VCAM-1, p = 0.592) between baseline and 1 week follow-up.

CONCLUSION

On a cohort basis, CEC enumeration and activation are reproducible in youth. Relatively high individual biological variability may limit its clinical utility.

Endothelial dysfunction and coronary artery disease: a state of the art review

Atherosclerotic coronary artery disease (CAD) is a major cause of morbidity and mortality in the developed world. Endothelial dysfunction plays an important role in the development of atherosclerosis and predicts cardiovascular (CV) outcomes independent of conventional CV risk factors. In recent years, there have been tremendous improvements in the pharmacological prevention and management of CAD. In this review, the pathophysiology of endothelial dysfunction in relation to CAD is discussed and various techniques of invasive and noninvasive assessments of peripheral and coronary endothelial function described. In addition, evidence for the association of endothelial dysfunction and CV outcomes has been examined and finally the role of therapeutic interventions in endothelial dysfunction has been discussed.

Circulating endothelial cells in children: role of fitness, activity, and adiposity

PURPOSE

Circulating endothelial cells (CEC) are thought to be useful biomarkers of endothelial dysfunction and overall cardiovascular health. The extent to which CEC are influenced by fitness, physical activity, and adiposity in youth remains unknown, as they have seldom been examined in the pediatric population. This study assessed resting levels of CEC in boys and girls of different chronological and biological age and explored the relationship between these cells and aerobic fitness, physical activity, and adiposity.

METHODS

Seventy-five children (39 males; median [interquartile range], age = 14.4 [5.8]) completed two study visits. During the first visit, basic anthropometric data were collected and biological age was calculated. Peak mechanical power (Wpeak) was determined using the McMaster All-Out Continuous cycling test. Participants then wore an accelerometer over a 7-d period to assess habitual levels of moderate-to-vigorous physical activity. During visit 2, percent body fat (%BF) was assessed by dual-energy x-ray absorptiometry. A fasted blood sample was also collected from which concentrations of CEC, identified as CD31CD34CD45CD133, were quantified by flow cytometry.

RESULTS

No differences were seen in CEC by sex, chronological age, or biological age. The median (interquartile range) CEC concentration was 32.3 × 10 (63.0 × 10), representing 1.3% (2.7%) of collected peripheral blood mononuclear cells. CEC concentration was associated with Wpeak normalized to lean body mass (r = 0.36, P < 0.01) and time spent in moderate-to-vigorous physical activity (r = -0.27, P = 0.02). No relationship was observed between CEC and %BF.

CONCLUSION

Healthy children demonstrate relatively low concentrations of CECs. Because CEC represent a population of mature endothelial cells shed from the intima after irreversible damage, they may be more reflective of recent physical activity levels rather than fitness or level of adiposity.

Obesity and coronary microvascular disease - implications for adipose tissue-mediated remote inflammatory response

It is believed that obesity has detrimental effects on the coronary circulation. These include immediate changes in coronary arterial vasomotor responsiveness and the development of occlusive large coronary artery disease. Despite its critical role in regulating myocardial perfusion, the altered behavior of coronary resistance arteries, which gives rise to coronary microvascular disease (CMD) is poorly understood in obesity. A chronic, low-grade vascular inflammation has been long considered as one of the main underlying pathology behind CMD. The expanded adipose tissue and the infiltrating macrophages are the major sources of pro-inflammatory mediators that have been implicated in causing inadequate myocardial perfusion and, in a long term, development of heart failure in obese patients. Much less is known the mechanisms regulating the release of these cytokines into the circulation that enable them to exert their remote effects in the coronary microcirculation. This mini review aims to examine recent studies describing alterations in the vasomotor function of coronary resistance arteries and the role of adipose tissue-derived pro-inflammatory cytokines and adipokines in contributing to CMD in obesity. We provide examples of regulatory mechanisms by which adipokines are released from adipose tissue to exert their remote inflammatory effects on coronary microvessels. We identify some of the important challenges and opportunities going forward.

Circulating endothelial cells and chronic kidney disease

Endothelial dysfunction may play a crucial role in initiation of the pathogenesis of vascular disease and atherosclerosis. The identification and quantification of circulating endothelial cells (CEC) have been developed as a novel marker of endothelial function. We describe, in great detail, mechanisms of endothelial dysfunction and CEC detachment. We also review the relationship between numbers of CEC and disease severity and response to treatment. In addition, we describe the possible clinical use of CEC in chronic kidney disease (CKD) and kidney transplantation. In summary, CEC have been developed as a novel approach to assess the endothelial damage. Measurement of the CEC level would provide an important diagnostic and prognostic value on the endothelium status and the long-term outcome of vascular dysfunction.

Endothelial dysfunction in patients with primary aldosteronism: a biomarker of target organ damage

Primary aldosteronism (PA) has been associated with increased target organ damage (TOD), most likely through mineralocorticoid receptor-dependent endothelial dysfunction, in comparison with essential hypertension (EH). The aim of this study was to evaluate the level of biomarkers of endothelial dysfunction in PA and the relationship with left ventricular hypertrophy (LVH) and microalbuminuria (MAU). A total of 50 PA patients and 51 patients with EH individually matched for age, sex, blood pressure and duration of hypertension participated in this study. Biomarkers of endothelial dysfunction, including von Willebrand factor (vWF), intercellular adhesion molecule 1 (ICAM-1) and oxidized low-density lipoprotein (ox-LDL), were measured. Plasma aldosterone concentration (PAC), MAU and echocardiography were also evaluated. In PA patients, vWF, ICAM-1, ox-LDL, LVH and MAU were all significantly higher than in EH patients (all P<0.05). Furthermore, LVH was positively correlated with PAC (P=0.002), vWF (P=0.013) and ox-LDL (P=0.020). MAU was positively correlated with PAC (P<0.001), vWF (P=0.013) and ICAM-1 (P=0.001). Multiple regression analysis indicated that vWF, ICAM-1 and PAC independently predicted MAU (all P<0.05). Likewise, PAC, vWF and ox-LDL were significant predictors of LVH (all P<0.05). Taken together, our results suggest that endothelial dysfunction may contribute to TOD in PA patients.

Cellular biomarkers of endothelial health: microparticles, endothelial progenitor cells, and circulating endothelial cells

Endothelial dysfunction, the shift from a healthy endothelium to a damaged pro-coagulative, pro-inflammatory, and pro-vasoconstrictive phenotype, is an early event in many chronic diseases that frequently precedes cardiovascular complications. Functional assessment of the endothelium can identify endothelial damage and predict cardiovascular risk; however, this assessment provides little information as to the mechanisms underlying development of endothelial dysfunction. Changes in plasma asymmetric dimethyl arginine levels, markers of lipid peroxidation, circulating levels of inflammatory mediators, indices of coagulation and cellular surrogates such as microparticles, circulating endothelial cells, and endothelial progenitor cells may reflect alterations in endothelial status and as such have been defined as "biomarkers" of endothelial function. Biomarkers may be chemical or cellular. This review examines some markers of endothelial dysfunction, with a particular focus on cellular biomarkers of endothelial dysfunction and their diagnostic potential.

Salvianolic acid A protects against vascular endothelial dysfunction in high-fat diet fed and streptozotocin-induced diabetic rats

Salvianolic acid A (SalA) is one of the main active ingredients of Salvia miltiorrhizae. The objective of this study was to evaluate the effect of SalA on the diabetic vascular endothelial dysfunction (VED). The rats were given a high-fat and high-sucrose diet for 1 month followed by intraperitoneal injection of streptozotocin (30 mg/kg). The diabetic rats were treated with SalA (1 mg/kg, 90% purity) orally for 10 weeks after modeling, and were given a high-fat diet. Contractile and relaxant responses of aorta rings as well as the serum indications were measured. Our results indicated that SalA treatment decreased the level of serum Von Willebrand factor and ameliorated acetylcholine-induced relaxation and KCl-induced contraction in aorta rings of the diabetic rats. SalA treatment also reduced the serum malondialdehyde, the content of aortic advanced glycation end products (AGEs), and the nitric oxide synthase (NOS) activity as well as the expression of endothelial NOS protein in the rat aorta. Exposure of EA.hy926 cells to AGEs decreased the cell viability and changed the cell morphology, whereas SalA had protective effect on AGEs-induced cellular vitality. Our data suggested that SalA could protect against vascular VED in diabetes, which might attribute to its suppressive effect on oxidative stress and AGEs-induced endothelial dysfunction.

N-3 Polyunsaturated fatty acid therapy improves endothelial function and affects adiponectin and resistin balance in the first month after myocardial infarction

INTRODUCTION

N-3 Polyunsaturated fatty acids (n-3 PUFA) exert clinical beneficial effects in patients after acute myocardial infarction (AMI). However, their exact mechanisms of action are not well recognized yet. Our aim was to evaluate effects of early introduced n-3 PUFA supplementation on endothelial function and serum adipokine concentrations in patients with AMI.

MATERIAL AND METHODS

Thirty-eight patients with AMI and successful coronary stent implantation were randomized to the study group (PUFA group: n = 19; standard therapy + PUFA 1 g daily) and the control group (control group: n = 19; standard therapy). The study group patients were given n-3 PUFA (Omacor 1 g daily) starting from the 3(rd) day of AMI. Ultrasound vascular indexes (flow-mediated dilatation [FMD], nitroglycerine-mediated dilation [NMD]) and serum concentrations of adiponectin and resistin (ELISA) were evaluated before and after 30 days of pharmacotherapy.

RESULTS

Comparison of the mean delta values (baseline/after 30 days of therapy) between groups revealed significant differences for delta FMD (PUFA 7.6 ±12.4% vs. control -1.7 ±10.5%, p = 0.019) and delta resistin concentrations (PUFA 1.0 ±3.8pg/ml vs. control -1.6 ±2.9pg/ml, p = 0.028). Multiple linear regression analysis for all subjects revealed the n-3 PUFA supplementation (r = 10.933, p = 0.004) and waist circumference (r = -0.467, p = 0.01) as independent factors associated with delta FMD values (R-adjusted 0.29; p = 0.002).

CONCLUSIONS

Early and short-term n-3 PUFA supplementation in AMI with successful primary PCI and optimal pharmacotherapy improves endothelial function. However, increased resistin serum levels observed after 1-month n-3 PUFA supplementation merits further investigations.

Vascular function and morphology in rheumatoid arthritis: a systematic review

OBJECTIVES

RA associates with significantly increased morbidity and mortality from cardiovascular disease (CVD). This may be due to complex interactions between traditional CVD risk factors, systemic rheumatoid inflammation and the vasculature. We reviewed the current literature to answer: (i) whether there is sufficient evidence that patients with RA have altered vascular function and morphology compared with normal controls; (ii) whether there is sufficient evidence to determine if such changes relate predominantly to systemic inflammation; and (iii) whether any changes of vascular function and morphology in RA can be modified with therapy.

METHODS

The MEDLINE database was searched to identify publications from 1974 to 1 November 2010 pertaining to vascular function and morphology in RA. The total number of articles included in the present review was 93. This included 57 cross-sectional studies, 27 longitudinal studies without randomization and 9 longitudinal studies with randomization.

RESULTS

Vascular function and morphology was impaired in RA relative to healthy controls. The majority of studies reported no associations between systemic inflammation and vascular function. Treatment with anti-inflammatory medication resulted in both transient and long-term improvements in the vasculature, but only a few studies reported associations between change in inflammation and change in vascular function and morphology.

CONCLUSION

The link between systemic inflammation and vascular function and morphology is not wholly supported by the available literature. Long-term studies examining specific predictors (including CVD risk factors) on the vasculature in RA are needed.

The effect of increased dietary fruit and vegetable consumption on endothelial activation, inflammation and oxidative stress in hypertensive volunteers

BACKGROUND AND AIMS

Public health campaigns recommend increased fruit and vegetable (FV) consumption as an effective means of cardiovascular risk reduction. During an 8 week randomised control trial among hypertensive volunteers, we noted significant improvements in endothelium-dependent vasodilatation with increasing FV consumption. Circulating indices of inflammation, endothelial activation and insulin resistance are often employed as alternative surrogates for systemic arterial health. The responses of several such biomarkers to our previously described FV intervention are reported here.

METHODS AND RESULTS

Hypertensive volunteers were recruited from medical outpatient clinics. After a common 4 week run-in period during which FV consumption was limited to 1 portion per day, participants were randomised to 1, 3 or 6 portions daily for 8 weeks. Venous blood samples for biomarker analyses were collected during the pre and post-intervention vascular assessments. A total of 117 volunteers completed the 12 week study. Intervention-related changes in circulating levels of high sensitivity C-reactive protein (hsCRP), soluble intracellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), von Willebrand factor (vWF) and plasminogen activator inhibitor-1 (PAI-1) did not differ significantly between FV groups. Similarly, there were no significant between group differences of change in homeostasis model assessment (HOMA) scores.

CONCLUSIONS

Despite mediating a significant improvement in acetylcholine induced vasodilatation, increased FV consumption did not affect a calculated measure of insulin resistance or concentrations of the circulating biomarkers measured during this study. Functional indices of arterial health such as endothelium-dependent vasomotion are likely to provide more informative cardiovascular end-points during short-term dietary intervention trials.

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.

Particulate matter induces translocation of IL-6 from the lung to the systemic circulation

The biological mechanisms responsible for an association between elevated concentrations of ambient particulate matter (PM) and increased cardiovascular morbidity and mortality remain unclear. Our laboratory showed that exposure to PM induces systemic inflammation that contributes to vascular dysfunction. This study was designed to determine whether the lung is a major source of systemic inflammatory mediators, using IL-6 as a surrogate marker. We also sought to determine the impact on vascular dysfunction after exposure to PM of less than 10 μm in diameter (PM(10)). C57BL/6 mice were intratracheally exposed to a single instillation of PM(10) (10 or 200 μg) or saline. Four hours or 24 hours after exposure, venous and arterial blood samples were simultaneously collected from the right atrium and descending aorta. Concentrations of IL-6 were measured in bronchoalveolar lavage fluid (BALF) and serum samples. Vascular functional responses to acetylcholine (ACh) and phenylephrine were measured in the abdominal aorta. Concentrations of IL-6 in BALF samples were increased at 4 and 24 hours after exposure to PM(10). At baseline, concentrations of IL-6 in venous blood were higher than those in arterial blood. Exposure to PM(10) reversed this arteriovenous gradient, 4 hours after exposure. The relaxation responses of the abdominal aorta to ACh decreased 4 hours after exposure to 200 μg PM(10). In IL-6 knockout mice, the instillation of recombinant IL-6 increased IL-6 concentrations in the blood, and exposure to PM(10) did not cause vascular dysfunction. These results support our hypothesis that exposure to PM(10) increases pulmonary inflammatory mediators that translocate to the circulation, contributing to systemic inflammation, with downstream effects such as vascular dysfunction.

The endotheliome: a new concept in vascular biology

As the importance of the endothelium is becoming increasingly recognised, additional tools are needed to assess its functions. Separate studies have looked at different aspects of vascular biology primarily focusing on the central role of the endothelium, i.e. secretion/release of molecules in the plasma, physiological action on other cells, and the presence of endothelial cells themselves in the circulation. Targeting and protecting the endothelium is a promising therapeutic strategy for modifying a number of disease processes but 'ideal' methods to monitor this treatment, like many other tools for assessing endothelial activity, remain elusive. We suggest that a broader view of the endothelium is important, and with it the concept of the assessment of overall vascular function, which fuses different aspects of endothelial activity into a unifying concept. In the present document we review the current understanding of endothelial biology and the methods of its assessment, and hypothesise that a more multifactorial approach to the endothelium will be a crucial determinant of outcomes and treatment strategies for different diseases. This we describe as the 'endotheliome'.

Flow-mediated vasodilation and endothelium function in children with postural orthostatic tachycardia syndrome

The study was designed to explore flow-mediated vasodilation (FMD) and endothelium function in children with postural orthostatic tachycardia syndrome (POTS). The patient group consisted of 46 children 12 +/- 3 years of age who were diagnosed with POTS from June 2008 to January 2009 by head-up test or head-up tilt test at Peking University First Hospital. Twenty healthy children 12 +/- 4 years of age were selected for the control group. Plasma concentrations of nitric oxide (NO) and activity of NO synthase (NOS) were determined in the patient and control groups. FMD of each participant's brachial artery was measured using color Doppler vascular ultrasound and a comparison of FMDs and plasma NO and NOS activities between the 2 groups was done using independent t test. No significant differences were found between the POTS and control groups in age, sex ratio, height, body weight, baseline blood pressure, heart rate, and baseline brachial artery diameter. Patients in the POTS group had larger FMD (10.8 +/- 4.4%) than children in the control group (5.7 +/- 2.2%), and this difference was significant (p <0.01). Plasma NO and NOS levels were significantly higher in the POTS group than in the control group (NO 74 +/- 19 micromol/L in POTS group vs 62 +/- 6 micromol/L in control group, p <0.01; NOS 21 +/- 3 U/mL in POTS group vs 15 +/- 1 U/mL in control group, p <0.01). In addition, there was a significant correlation between FMD and the NOS activity. In conclusion, augmented FMD and abnormal function of vascular endothelium may play an important role in POTS in children.

The relationship between endothelial damage and aortic augmentation index

Augmentation index (AIx), a measure of wave reflection, is regulated by a number of factors, including endothelial function and vascular smooth muscle tone. The relationship between local endothelium-derived factors and AIx is well known; however, association between endothelial damage markers and AIx has not been sufficiently studied. This study investigates whether endothelial damage markers-von Willebrand factor (vWF) soluble thrombomodulin (sTM)--are associated with wave reflections. We studied 46 (48.5 +/- 10.6, years) never-treated patients with hypertension (HT) and an age-matched control group of 40 (47 +/- 8.6, years) normotensive individuals. von Willebrand factor and sTM levels were determined in all subjects. We evaluated the aortic AIx of the study population using applanation tonometry (Sphygmocor, AtCor Medical, Sydney, Australia). The heart rate-corrected augmentation index (AIx@75) was estimated as a marker of wave reflections. Endothelial damage markers and AIx@75 were significantly higher in hypertensive patients than in controls. In the whole population, the vWF level (beta = 0.24, p = 0.01) was an independent determinant of AIx@75 in multivariate analysis. However, the sTM level was not associated with AIx@75. We found that the vWF level was an independent determinant of AIx@75. Our results suggest that increased an vWF level contributes significantly to increased wave reflections.

Impaired glucose tolerance and endothelial damage, as assessed by levels of von Willebrand factor and circulating endothelial cells, following acute myocardial infarction

BACKGROUND

Impaired glucose tolerance (IGT) following acute myocardial infarction (AMI) increases the incidence of major adverse cardiac events. We hypothesized that endothelial damage following AMI, as assessed by levels of von Willebrand factor (vWF) and circulating endothelial cells (CECs), would be more pronounced in patients with IGT compared to those with normal glucose tolerance (NGT).

METHODS

We studied non-diabetic patients with AMI (n=125; 107 (86%) male; mean age 59 years (SD 12.5)) who underwent oral glucose tolerance testing 3-5 days after admission. We measured vWF (enzyme-linked immunosorbent assay) and CECs (CD146 immunobead capture) in the fasting state and at 2 h post glucose load.

RESULTS

Base-line vWF and CEC levels were higher in IGT patients versus those with NGT and healthy controls (HC) (P<0.001). The acute increase in vWF and CECs in response to the glucose load was significantly higher in the IGT group compared to those with NGT and HC (P<0.01)-an increase on a par with that seen in newly diagnosed diabetics.

CONCLUSION

The degree of endothelial damage post AMI in patients with IGT is greater than NGT, and comparable to that seen in frank diabetes mellitus. Subjects with IGT therefore need to be as actively sought and managed.

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.

Effect of obesity on pulmonary inflammation induced by acute ozone exposure: role of interleukin-6

To determine the role of interleukin (IL)-6 in the increased ozone (O3)-induced inflammation and injury observed in obese vs. lean mice, lean wild-type and leptin-deficient obese (ob/ob) mice were injected with anti-IL-6 antibody (Ab) or isotype control Ab 24 h before exposure to either O3 (2 ppm for 3 h) or room air. Four or 24 h after O3 exposure, bronchoalveolar lavage (BAL) was performed, and the lungs were harvested for Western blotting. Anti-IL-6 Ab caused substantial reductions in O3-induced increases in BAL IL-6 in mice of both genotypes. Four hours following O3, ob/ob mice had increased BAL neutrophils compared with controls, and anti-IL-6-Ab virtually abolished this difference. At 24 h, O3-induced increases in BAL protein and BAL serum albumin were augmented in ob/ob vs. wild-type mice, and anti-IL-6 Ab ablated these obesity-related differences in epithelial barrier injury. O3 increased tyrosine phosphorylation of STAT-3 and STAT-1. There was no effect of obesity on STAT-3 phosphorylation, whereas obesity decreased STAT-1 expression, resulting in reduced STAT-1 phosphorylation. IL-6 neutralization did not alter STAT-3 or STAT-1 phosphorylation in ob/ob or wild-type mice. O3 increased BAL leukemia inhibitory factor (LIF) to a greater extent in obese than in lean mice, and LIF may account for effects on STAT phosphorylation. Our results suggest that IL-6 plays a complex role in pulmonary responses to O3, a role that differs between wild-type and ob/ob mice. Moreover, obesity-related differences in activation of STAT proteins may contribute to some of the differences in the response of obese vs. lean mice.

Non-traditional biomarkers of atherosclerosis in stable and unstable coronary artery disease, do they differ?

BACKGROUND

Biomarkers of atherosclerosis are emerging as a potential tool for assessment of coronary artery disease (CAD) patients. As acute coronary syndrome (ACS), and stable CAD are distinguished in their pathophysiology it is conceivable that they are also characterized by different biomarkers of atherosclerosis.

METHODS

We systematically reviewed the literature for clinical studies of several non-traditional biomarkers of atherosclerosis reflecting various pathophysiological processes, namely macrophage-activity, oxidative-stress, tissue remodeling, and thrombosis in ACS and stable CAD to determine whether circulating biomarkers are differently expressed/predict outcome in these two clinical conditions.

RESULTS

Macrophage-activity (monocyte chemoattractant protein-1, neopterin), tissue-remodeling (matrix metalloproteinase-9) and thrombosis (tissue-factor) related biomarkers were consistently elevated in ACS compared to stable CAD, in accordance with the pathophysiological role of these mediators in plaque rupture, characterizing ACS. Thus, these biomarkers may be applicable for diagnosis of ACS. Additionally, neopterin was consistently shown to predict outcome in both stable and ACS patients and myeloperoxidase was strongly shown to predict outcome in ACS, implying for their potential role in risk stratification of these patients.

CONCLUSIONS

As ACS and stable CAD are characterized by different pathophysiological processes, it appears that the biomarkers that are associated with them are differently expressed in these two clinical conditions

Early initiation of low-dose atorvastatin treatment after an acute ST-elevated myocardial infarction, decreases inflammatory process and prevents endothelial injury and activation

BACKGROUND

High-dose statin treatment improves clinical outcome of ST-elevated myocardial infarction (STEMI). However, the effect of low-dose atorvastatin treatment on inflammatory and pro-thrombotic molecules during the post-STEMI period is unclear. We investigated the effect of low-dose atorvastatin treatment on the kinetics of cytokine IL-6, vascular cell adhesion molecule (sVCAM-1) and endothelium-derived markers of thrombosis/fibrinolysis such as von Willebrand factor (vWF), plasminogen activator inhibitor-1 (PAI-1) and tissue plasminogen activator (tPA), post STEMI.

METHODS

Twenty-four normocholesterolemic patients with STEMI were randomised to receive atorvastatin 10mg/day or no statin treatment for 6 weeks after the event. Blood samples were obtained by their admission to the hospital as well as at weeks 1 and 6. Circulating levels of IL-6, sVCAM-1, vWF, PAI-1 and tPA were determined by ELISA.

RESULTS

Atorvastatin induced a decrease of IL-6 at 1 week, an effect which reached significance compared to baseline at 6 weeks post STEMI (p<0.05 vs baseline). Serum sVCAM-1 was increased in controls both at 1 and 6 weeks post-STEMI (p<0.05 vs baseline), an effect prevented by atorvastatin. Plasma vWF was increased 1 week post-STEMI in controls (p<0.05 vs baseline) and returned to baseline at 6 weeks, an effect prevented by atorvastatin. Plasma PAI-1, tPA and the PAI-1/tPA ratio remained unchanged in both groups.

CONCLUSION

Early initiation of low-dose atorvastatin treatment decreases the expression of IL-6 and sVCAM-1 and the release of vWF in patients with STEMI. Therefore, low-dose atorvastatin, modulates inflammatory response and decreases endothelial injury and activation in patients with recent STEMI.

Tissue factor in thrombosis and hemorrhage

The research aims of our laboratory are to provide a realistic description of biologic processes involved in protection from hemorrhage and the evolution of thrombosis. To evaluate these processes, we use 4 models of coagulation ranging from 1) studies of blood exiting from microvascular wounds in humans through 2) minimally altered whole blood induced to clot by tissue factor (TF) to 3) reconstitution of the blood coagulation proteome with purified components and to 4) mathematical descriptions of the chemical processes and dynamics that occur. The integration of these 4 models permits comprehensive analyses of the blood coagulation system and predictions of its behavior under normal and pathologic conditions. Data accumulated thus far have led to advances in our understanding of 1) the processes occurring during the initiation and propagation phases of thrombin generation, 2) the roles for individual proteins involved in blood coagulation and its regulation, 3) defects in thrombin generation and clot formation in hemophilia, 4) actions and limitations of pharmacologic agents used to control hemorrhage, thrombosis, and chronic cardiovascular disease, and 5) the relationship between genotypic and phenotypic features of an individual's plasma proteome and his/her immediate and long-term thrombotic risk.

Plasma interleukin-6 and tumor necrosis factor-alpha can predict coronary endothelial dysfunction in hypertensive patients

Coronary endothelial function is impaired in hypertension; however, the severity of this impairment varies among patients. We aimed to identify the predictors of coronary endothelial dysfunction among clinical variables related to hypertension and atherosclerosis. Twenty-seven untreated, uncomplicated essential hypertensive patients and 10 age-matched healthy controls were studied prospectively. Myocardial blood flow (MBF) was measured by using (15)O-water positron emission tomography (PET) at rest and during a cold pressor test (CPT). Coronary vascular resistance (CVR) during CPT was used as a marker of coronary endothelial function. Serum low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, triglycerides, malondialdehyde-LDL, homeostasis model assessment, high-sensitivity C-reactive protein (hs-CRP), and plasma interleukin-6 (IL-6) and tumor necrosis factor (TNF)-alpha were also measured. CVR during CPT was significantly higher in hypertensive patients than in healthy controls (114+/-26 vs. 94+/-12 mmHg/[mL/g/min]; p<0.05). By univariate analysis, CVR during CPT was correlated with LDL cholesterol (r=0.38, p<0.05), IL-6 (r=0.46, p<0.02), and TNF-alpha (r=0.39, p<0.05) in hypertensive patients. By multivariate analysis, IL-6 and TNF-alpha were significant independent predictors of CVR during CPT. Elevated plasma IL-6 and TNF-alpha levels were independent predictors of coronary endothelial dysfunction in hypertensive patients. These results suggest that plasma IL-6 and TNF-alpha might be useful for identifying the high risk subgroup of hypertensive patients with coronary endothelial dysfunction and provide an important clue to link systemic inflammation to the development of coronary atherosclerosis.

Exercise induced von Willebrand Factor release -- new model for routine endothelial testing

Endothelial dysfunction (ED) is actively involved in the mechanism of occurrence, development and progression of all the degrees of atherosclerosis. The established impact of ED on the progress and outcome of cardiovascular diseases, together with convincing indications of a possible successful therapeutic modification, necessitate the changeover of ED assessment from experimental to a routine practice. As there is no appropriate method for a clinical practice, scientists anticipate significant research efforts in the further development. Among numerous methods already available, von Willebrand Factor (vWF) stands out significantly. In accordance with the accepted leading diagnostic role of vWF baseline levels in the group of peripheral endothelial markers, and earlier scientific observations on the absence of its expected reactivation during physical exercise, we hypothesised this promising theory. We believe that a constant stronger release of vWF in endothelial cell injury leads to the exhaustion of its stores in Weibel-Palade bodies with the consequent absence of the expected rise of concentration during the exercise. Therefore, we hypothesised that ED could be exhaustible vWF endothelopathy and the exercise induced release of vWF a new, simple, safe and reliable test for the detection of ED and monitoring of the expected therapeutic effect. In order to have a final clinical usability of the proposed diagnostic model, it is necessary to test its reliability in different pathological and risk states, and establish susceptibility in therapeutic procedures. The correlation with invasive functional angiographic tests and the flow mediated dilatation test of peripheral arteries also needs to be validated. We expect the proposed test of vWF inducibility to find its place in clinical practice, i.e. in prevention, prediction and therapy of cardiovascular diseases.

Serum interleukin-6 correlates with endothelial dysfunction in healthy men independently of insulin sensitivity

OBJECTIVE

Interleukin (IL)-6 is a proinflammatory cytokine that is implicated in the pathogenesis of atherosclerosis and insulin resistance. Both endothelial dysfunction and insulin resistance are among the earliest abnormalities that can be detected in people at risk for cardiovascular events. We aimed to evaluate whether increased serum IL-6 concentrations associated with endothelial dysfunction are independent of insulin sensitivity in apparently healthy men.

RESEARCH DESIGN AND METHODS

Association studies were performed in well-characterized nondiabetic Caucasian men (n = 99) recruited for energy balance studies. Insulin sensitivity (minimal model) and brachial vascular reactivity (high-resolution external ultrasound) were assessed. Circulating IL-6 concentrations were measured by enzyme-linked immunosorbent assay.

RESULTS

Serum IL-6 was an independent contributor to the variance of endothelium-dependent vasodilatation after adjusting for age, BMI, smoking status, LDL cholesterol, systolic blood pressure, diastolic blood pressure, and insulin sensitivity (P = 0.001). In fact, circulating IL-6 was negatively associated with endothelium-dependent vasodilatation (r = -0.247, P = 0.014) and insulin sensitivity (r = -0.262, P = 0.011) and correlated positively with age (r = 0.241, P = 0.016), BMI (r = 0.240, P = 0.017), systolic blood pressure (r = 0.299, P = 0.003), diastolic blood pressure (r = 0.295, P = 0.003), and triglycerides (r = 0.212, P = 0.035). No significant associations were observed between endothelium-independent vasodilatation and serum IL-6 concentrations.

CONCLUSIONS

Circulating IL-6 is linked to endothelial dysfunction independently of insulin sensitivity in apparently healthy men.

Temporal and venepuncture-related decline in circulating endothelial cell capture from mixed venous blood

BACKGROUND

The quantification of circulating endothelial cells (CECs) in whole blood has evolved as a novel method for the assessment of endothelial function, although major methodological issues remain. We hypothesized that there is a temporal decline in CEC counts in static venesected blood and that venepuncture itself may lead to increased CEC detachment.

METHODS

CEC isolation was performed using the immunobead method. For the temporal decline experiment, we included 52 patients presenting with acute coronary syndrome (ACS). We performed CEC counts immediately and at 4 and 24 h later. For the venepuncture decline experiment, we studied 40 patients with stable cardiovascular disease (CVD). CEC counts were determined from the first 4 mL of aspirated venous blood and compared with counts obtained from a subsequent 4 mL sample of blood after at least 7.5 mL of blood had been collected.

RESULTS

Among the ACS patients there was a significant temporal decline in CEC counts in static venous blood over a 24 h period (p = 0.013). Among the patients with stable CVD, the median CEC counts obtained from the initial 4 mL of aspirated venous blood were significantly higher (by 32%) than that obtained from the later 4 mL of aspirated venous blood (p = 0.041).

CONCLUSIONS

We demonstrated a significant temporal fall in CEC numbers in static venous blood over 24 h following venesection. Furthermore, we have shown that CEC counts are higher in the initial aspirated blood compared with that aspirated from the same needle subsequently. These data would have implications for how CEC determination is undertaken by researchers in studies related to ACS or CVD.

GATA2 is associated with familial early-onset coronary artery disease

The transcription factor GATA2 plays an essential role in the establishment and maintenance of adult hematopoiesis. It is expressed in hematopoietic stem cells, as well as the cells that make up the aortic vasculature, namely aortic endothelial cells and smooth muscle cells. We have shown that GATA2 expression is predictive of location within the thoracic aorta; location is suggested to be a surrogate for disease susceptibility. The GATA2 gene maps beneath the Chromosome 3q linkage peak from our family-based sample set (GENECARD) study of early-onset coronary artery disease. Given these observations, we investigated the relationship of several known and novel polymorphisms within GATA2 to coronary artery disease. We identified five single nucleotide polymorphisms that were significantly associated with early-onset coronary artery disease in GENECARD. These results were validated by identifying significant association of two of these single nucleotide polymorphisms in an independent case-control sample set that was phenotypically similar to the GENECARD families. These observations identify GATA2 as a novel susceptibility gene for coronary artery disease and suggest that the study of this transcription factor and its downstream targets may uncover a regulatory network important for coronary artery disease inheritance.

Coronary artery disease (CAD) is the most common form of heart disease in the Western world and is one of the leading causes of death in the United States. CAD is inherited and is a complex genetic disease because it results from changes to multiple genes acting in concert with one another and the environment. The authors locate CAD susceptibility genes by convergence of techniques and identify variation within a gene of interest in an early-onset CAD population. If a specific variant is found more often in affected individuals or families than in controls, this can suggest that this gene variant is associated with disease. The authors have identified a gene, GATA2, which is located in a genomic region suspected to contain genes for CAD and displays expression patterns predictive of location of disease within human donor aortas. They have identified several GATA2 variants that segregate with CAD in a family-based early-onset CAD population and have further validated two of these associations in a separate young case-control sample affected with CAD. These data imply that the transcription factor GATA2 may play a role in CAD susceptibility and suggest that the study of GATA2 targets may uncover a set of GATA2-regulated genes important to CAD inheritance.