Association of circulating endothelial microparticles with cardiometabolic risk factors in the Framingham Heart Study

Circulating endothelial microparticles are elevated in bicuspid aortic valve disease and related to aortic dilation

BACKGROUND/OBJECTIVES

The mechanisms underlying aortic dilation in bicuspid aortic valve (BAV) disease are unknown. Circulating endothelial microparticles (EMPs) have emerged as biomarkers of endothelial damage. We sought to evaluate the relationships among EMPs, BAV disease, and aortic dilation.

METHODS

Four evaluations were used. Circulating EMPs (PECAM(+), E-selectin(+)) were compared between BAV patients and tricuspid aortic valve (TAV) control subjects. The variables related to circulating EMPs were investigated in BAV patients. Circulating EMP levels were compared between BAV and TAV patients with a dilated aorta. Finally, circulating EMPs in BAV patients were evaluated over time with respect to aortic valve surgery (AVS) or aortic surgery.

RESULTS

We observed higher levels of circulating PECAM(+) EMPs in the BAV patients than in the control subjects (3.98±0.2 vs. 2.39±0.4 per log PECAM(+) EMPs/μl, p=0.001). Aortic dilation was the most significant variable that correlated with the PECAM(+) EMP levels in the BAV patients (β=0.321, p=0.008). The BAV patients with aortic dilation exhibited higher PECAM(+)EMP levels than the TAV patients with dilated aortas, and this correlation was independent of aortic valve function. We observed a drastic decrease in the circulating PECAM(+) EMPs following AVS and aortic root replacement (4.27±0.6 and 1.75±0.3 per log PECAM(+)EMPs/μl, p=0.002).

CONCLUSION

The observed pattern of higher circulating PECAM(+) EMP levels links BAV disease to endothelial damage and aortic dilation. Circulating PECAM(+) EMPs were identified as a biological variable related to aortic dilation in patients with BAV disease.

Microparticle-Induced Coagulation Relates to Coronary Artery Atherosclerosis in Severe Aortic Valve Stenosis

Background

Circulating microparticles (MPs) derived from endothelial cells and blood cells bear procoagulant activity and promote thrombin generation. Thrombin exerts proinflammatory effects mediating the progression of atherosclerosis. Aortic valve stenosis may represent an atherosclerosis-like process involving both the aortic valve and the vascular system. The aim of this study was to investigate whether MP-induced thrombin generation is related to coronary atherosclerosis and aortic valve calcification.

Methods

In a cross-sectional study of 55 patients with severe aortic valve stenosis, we assessed the coronary calcification score (CAC) as indicator of total coronary atherosclerosis burden, and aortic valve calcification (AVC) by computed tomography. Thrombin-antithrombin complex (TATc) levels were measured as a marker for thrombin formation. Circulating MPs were characterized by flow cytometry according to the expression of established surface antigens and by measuring MP-induced thrombin generation.

Results

Patients with CAC score below the median were classified as patients with low CAC, patients with CAC Score above the median as high CAC. In patients with high CAC compared to patients with low CAC we detected higher levels of TATc, platelet-derived MPs (PMPs), endothelial-derived MPs (EMPs) and MP-induced thrombin generation. Increased level of PMPs and MP-induced thrombin generation were independent predictors for the severity of CAC. In contrast, AVC Score did not differ between patients with high and low CAC and did neither correlate with MPs levels nor with MP-induced thrombin generation.

Conclusion

In patients with severe aortic valve stenosis MP-induced thrombin generation was independently associated with the severity of CAC but not AVC indicating different pathomechanisms involved in coronary artery and aortic valve calcification.

Leptin induces the generation of procoagulant, tissue factor bearing microparticles by human peripheral blood mononuclear cells

BACKGROUND

Obesity is linked to increased thrombotic risk. Circulating leptin concentration correlates with body mass index. Microparticles are small (.05-1 μm) vesicles shed by activated and apoptotic cells, involved in numerous pathophysiologically relevant phenomena including blood coagulation and thrombosis. We tested the hypothesis that leptin induces the shedding of procoagulant, tissue factor bearing microparticles by human peripheral blood mononuclear cells, and investigated the intracellular mechanisms leading to microparticle release upon incubation with leptin.

METHODS

Peripheral blood mononuclear cells were isolated from healthy donors. Cells were incubated with leptin in the presence or in the absence of a phospholipase C inhibitor, U73122, a calmodulin inhibitor, W-7, and three inhibitors of mitogen activated protein kinases. Microparticle generation was assessed as phosphatidylserine concentration with a prothrombinase assay and by cytofluorimetric analysis. Tissue factor expression on microparticles was measured with a one-stage clotting assay. Intracellular calcium concentration was assessed by a fluorescent probe.

RESULTS

Leptin increased intracellular calcium mobilization and stimulated the generation of tissue factor-bearing MP by peripheral blood mononuclear cells, as assessed by phosphatidylserine quantification, clotting tests and flow-cytometry. U73122, PD98059 (an extracellular signal-regulated kinase1/2 inhibitor), and W-7, significantly inhibited leptin-induced MP release. SB203580 (a p38 inhibitor), and SP600125 (a c-Jun N-terminal kinase inhibitor) had no effect.

CONCLUSION

Leptin-induced generation of procoagulant microparticles might represent a link between obesity and atherothrombotic risk. Inhibition of leptin-induced microparticle generation might prove a viable strategy for the reduction of such risk in obese individuals.

Study of endothelial function response to exercise training in hypertensive individuals (SEFRET): study protocol for a randomized controlled trial

Background

Endothelial dysfunction is a hallmark of diabetes mellitus and systemic arterial hypertension (SAH) and an early maker for atherosclerosis. Aerobic exercise training is known to enhance endothelial function, but little is understood about the effects of resistance or combined exercise training on endothelial function. The aim of this study is to investigate the effect of a 12-week aerobic (AT), resistance (RT), or combined (aerobic and resistance, CT) training program on endothelial function and assess associated effects on blood pressure in individuals with SAH.

Methods/design

Eighty-one subjects with SAH aged 18 to 70 years will be selected and randomly assigned to three types of exercise training: AT, RT or CT. The study will involve the following procedures and tests: anamnesis, anthropometric assessment, echocardiography, blood pressure measurements through ambulatory blood pressure monitoring, flow-mediated dilation, ergospirometry, one repetition maximum test (1-RM), and blood collection (number of circulating endothelial progenitor cells, number of circulating endothelial microparticles, lipid profile, glucose, glycated hemoglobin, and creatinine). The AT intervention will consist of a 40-min exercise session with progressive intensities ranging from 50 to 75 % of heart rate reserve. The RT intervention will consist of a 40-minute session with four sets of six to 12 repetitions with a rest period of 60 to 90 seconds between each set and each type of exercise. Weight loads will be adjusted to 60 to 80 % of 1-RM for six types of exercise. The CT intervention will consist of a 20-min aerobic exercise session, followed by an additional 20-min resistance exercise session; each resistance exercise will have two sets less to match the total training volume.

Discussion

The study results are expected evidence of cardiovascular protective effects of different types of exercise training through the modulation of endothelial function in hypertensive individuals. Knowing the magnitude of improvement of endothelium-dependent vasodilation for the different types of exercise training can provide scientific evidence for the prescription of exercise programs for vascular protection targeting hypertensive individuals.

Trial registration

The Brazilian Clinical Trials Registry (http://www.ensaiosclinicos.gov.br/) under RBR-9ygmdn and dated 1 March 2015.

Clinical Significance of Endothelial Dysfunction in Essential Hypertension

The endothelium is recognized as a major determinant of vascular physiology and pathophysiology. Over the last few decades, a plethora of studies have implicated endothelial dysfunction in the progression of atherosclerosis and the subclinical target organ damage observed in essential hypertension. However, the clinical significance of diagnosing endothelial dysfunction in patients with essential hypertension remains under investigation. Although a number of vascular and non-vascular markers of endothelial dysfunction have been proposed, there is an ongoing quest for a marker in the clinical setting that is optimal, inexpensive, and reproducible. In addition, endothelial dysfunction emerges as a promising therapeutic target of agents that are readily available in clinical practice. In this context, a better understanding of its role in essential hypertension becomes of great importance. Here, we aim to investigate the clinical significance of endothelial dysfunction in essential hypertension by accumulating novel data on (a) early diagnosis using robust markers with prognostic value in cardiovascular risk prediction, (b) the association of endothelial dysfunction with subclinical vascular organ damage, and (c) potential therapeutic targets.

Microvesicles and exosomes: new players in metabolic and cardiovascular disease

The past decade has witnessed an exponential increase in the number of publications referring to extracellular vesicles (EVs). For many years considered to be extracellular debris, EVs are now seen as novel mediators of endocrine signalling via cell-to-cell communication. With the capability of transferring proteins and nucleic acids from one cell to another, they have become an attractive focus of research for different pathological settings and are now regarded as both mediators and biomarkers of disease including cardio-metabolic disease. They also offer therapeutic potential as signalling agents capable of targeting tissues or cells with specific peptides or miRNAs. In this review, we focus on the role that microvesicles (MVs) and exosomes, the two most studied classes of EV, have in diabetes, cardiovascular disease, endothelial dysfunction, coagulopathies, and polycystic ovary syndrome. We also provide an overview of current developments in MV/exosome isolation techniques from plasma and other fluids, comparing different available commercial and non-commercial methods. We describe different techniques for their optical/biochemical characterization and quantitation. We also review the signalling pathways that exosomes and MVs activate in target cells and provide some insight into their use as biomarkers or potential therapeutic agents. In summary, we give an updated focus on the role that these exciting novel nanoparticles offer for the endocrine community.

Extracellular Vesicle Proteins Associated with Systemic Vascular Events Correlate with Heart Failure: An Observational Study in a Dyspnoea Cohort

Background

SerpinF2, SerpinG1, CystatinC and CD14 are involved in inflammatory processes and plasma extracellular vesicle (EV) -levels of these proteins have been reported to be associated with systemic vascular events. Evidence is accumulating that inflammatory processes may play a pivotal role both in systemic vascular events and in heart failure. Therefore, we studied the association between plasma extracellular vesicle SerpinF2-, SerpinG1-, CystatinC and CD14-levels and the occurrence of acute heart failure in patients.

Methods and Result

Extracellular vesicle protein levels of SerpinG1, SerpinF2, CystatinC and CD14 were measured in an observational study of 404 subjects presenting with dysponea at the emergency department (4B-cohort). Plasma extracellular vesicles were precipitated in a total extracellular vesicles (TEX)-fraction and in separate LDL- and HDL-subfractions. Extracellular vesicle protein levels were measured with a quantitative immune assay in all 3 precipitates. Out of 404 subjects, 141 (35%) were diagnosed with acutely decompensated heart failure. After correction for confounders (including comorbidities and medications), levels of CD14 in the HDL-fraction (OR 1.53, p = 0.01), SerpinF2 in the TEX-and LDL-fraction (ORs respectively 0.71 and 0.65, p<0.05) and SerpinG1 in the TEX-fraction (OR 1.55, p = 0.004) were statistically significantly related to heart failure. Furthermore, extracellular vesicle CD14- and SerpinF2-levels were significantly higher in heart failure patients with preserved ejection fraction than in those with reduced ejection fraction.

Conclusion

Extracellular vesicle levels of CD14, SerpinG1 and SerpinF2 are associated with the occurrence of heart failure in subjects suspected for acute heart failure, suggesting common underlying pathophysiological mechanisms for heart failure and vascular events.

Pattern of circulating endothelial-derived microparticles among chronic heart failure patients with dysmetabolic comorbidities: The impact of subclinical hypothyroidism

The study aim was to evaluate the impact of dysmetabolic comorbidities including subclinical hypothyroidism (SH) on pattern of circulating endothelial-derived microparticles (EMPs) in chronic heart failure (CHF) patients.

METHODS

It was retrospectively involved a cohort of 388 patients with CHF. Fifty three CHF subjects had SH and 335 patients were free from thyroid dysfunction. Circulating levels of NT-pro brain natriuretic peptide (NT-pro-BNP), high-sensitivity C-reactive protein (hs-CRP), thyroid stimulating hormone (TSH), total and free thyroxine (T4) and triiodothyronine (T3) EMPs were measured at baseline. SH was defined per contemporary clinical guideline as state associated with elevated level of serum TSH>10 μU/L and basal normal free T3 and T4 concentration.

RESULTS

Circulating CD31+/annexin V+ EMPs were higher in SH patients compared with none SH subjects. In contrast, activated CD62E+ EMP numbers were not significantly different between both patient cohorts. Using C-statistics for Models with TSH, New York Heart Association (NYHA) class, dyslipidemia, and circulating biomarkers (hs-CRP, NT-proBNP, serum uric acid) as Continuous Variables we found that adding of NYHA class alone, NT-proBNP alone or their combination to the based model (TSH) improved the relative integrated discrimination improvement (IDI) for increased CD31+/annexin V+ to CD62E+ ratio by 4.9%; 9.2% and 9.6% respectively. NT-proBNP improves significantly predictive model based on TSH for increased CD31+/annexin V+ to CD62E+ ratio. Among patient study population for category-free net reclassification improvement (NRI), 4% of events (P=0.026) and 6% of non-events (P=0.012) were correctly reclassified by the addition of circulating NT-proBNP to the base model (TSH) for Increased CD31+/annexin V+ to CD62E+ ratio. Therefore, 4% of events (P=0.028) and 5% of non-events (P=0.014) were correctly reclassified using category-free NRI for increased CD31+/annexin V+ to CD62E+ ratio.

CONCLUSION

We found that SH state in CHF patients associates with impaired pattern of circulating EMPs with predominantly increased number of apoptotic-derived microparticles.

High correlation between 2 flow cytometry platforms in the microparticles analysis using a new calibrated beads strategy

Microparticles (MPs) are potential noninvasive biomarkers for diagnosis or prognosis in pathologic conditions. However, the lack of standardization of the preanalytical and analytical methods leads to a wide variability in MPs results. The recently developed Megamix-Plus beads, a new bead-based standardization tool optimized to specific types of flow cytometers, could help circumvent this problem. The aim of the present study was to determine whether the number of total MPs and platelet-derived MPs (PMPs) is similar using 2 different cytometer platforms calibrated with the Megamix-Plus beads. Blood samples from 65 patients with deep venous thrombosis were collected and processed to obtain platelet poor plasma (PPP). The number of total MPs and PMPs in each PPP sample was measured using 2 flow cytometers. Megamix-Plus side scatter channel beads were used to calibrate the LSRFortessa flow cytometer from Becton Dickinson, whereas Megamix-Plus forward scatter channel beads were applied to the Navios flow cytometer from Beckman Coulter. High correlation of total MPs and PMPs values between the flow cytometers was found (r = 0.908, P < 0.01 and r = 0.910, P < 0.001, respectively). However, the absolute numbers of total MPs and PMPs were significantly higher measured with the Navios flow cytometer compared with the LSRFortessa cytometer. Therefore, both platforms are valid for MPs determination in general, although a similar platform with the same calibration tool could be a better choice for multicenter studies.

The Association of Subclinical Hypothyroidism and Pattern of Circulating Endothelial-Derived Microparticles Among Chronic Heart Failure Patients

Background:

Subclinical hypothyroidism (SH) is diagnosed biochemically by the presence of normal serum free thyroxine concentration, in conjunction with an elevated serum thyroid-stimulating hormone level. Recent studies have demonstrated the frequent association between SH and cardiovascular diseases and risk factors.

Objectives:

To evaluate the impact of SH on patterns of circulating endothelial-derived microparticles, (EMPs) among chronic heart failure (CHF) patients

Patients and Methods:

This is a retrospective study involving a cohort of 388 patients with CHF. Fifty-three CHF subjects had SH and 335 patients were free from thyroid dysfunction. Circulating levels of N-terminal-pro brain natriuretic peptide (NT-proBNP), high-sensitivity C-reactive protein (hs-CRP), thyroid-stimulating hormone (TSH), total and free thyroxine (T4), and triiodothyronine (T3), and endothelial apoptotic microparticles (EMPs), were measured at baseline. SH was defined, according to contemporary clinical guidelines, as a biochemical state associated with an elevated serum TSH level of greater 10 μU/L and normal basal free T3 and T4 concentrations.

Results:

Circulating CD31+/annexin V+ EMPs were higher in patients with SH compared to those without SH. In contrast, activated CD62E+ EMP numbers were not significantly different between both patient cohorts. Using uni (bi) variate and multivariate age- and gender-adjusted regression analysis, we found several predictors that affected the increase of the CD31+/annexin V+ to CD62E+ ratio in the patient study population. The independent impact of TSH per 6.5 μU/L (odds ratio [OR] = 1.23, P = 0.001), SH (OR = 1.22, P = 0.001), NT-proBNP (OR = 1.19, P = 0.001), NYHA class (OR = 1.09, P = 0.001), hs-CRP per 4.50 mg/L (OR = 1.05, P = 0.001), dyslipidemia (OR = 1.06, P = 0.001), serum uric acid per 9.5 mmol/L (OR = 1.04, P = 0.022) on the increase in the CD31+/annexin V+ to CD62E+ ratio, was determined.

Conclusions:

We believe that the SH state in CHF patients may be associated with the impaired pattern of circulating EMPs, with the predominantly increased number of apoptotic-derived microparticles.

Impaired immune phenotype of circulating endothelial-derived microparticles in patients with metabolic syndrome and diabetes mellitus

INTRODUCTION

Type two diabetes mellitus (T2DM) remains a leading contributor to cardiovascular mortality worldwide. This study was conducted to investigate the pattern of circulating EMPs in T2DM patients in comparison with MetS subjects.

METHODS

The study retrospectively included 101 patients (54 subjects with T2DM and 47 patients with MetS) and 35 healthy volunteers. All the patients gave written informed consent for participation in the study. Biomarkers were measured at baseline of the study.

RESULTS

There is a significant difference between healthy subjects and patients regarding CD31+/annexin V+ EMPs to CD62E+ EMPs ratio, which reflects impaired phenotype of EMPs. Therefore, CD31+/annexin V+ EMPs to CD62E+ EMPs ratio was found to be higher in the T2DM patients compared to MetS patients. Using multivariate linear regression analyses, independent impact of T2DM (r = 0.40, P = 0.003), OPG (r = 0.37, P = 0.001), hs-CRP (r = 0.347, P = 0.001), and adiponectin (r = 0.33, P = 0.001) on increased CD31+/annexin V+ to CD62E+ ratio of EMPs was determined. Using C-statistics, we found that inflammatory biomarkers (hs-C-reactive protein, osteoprotegerin and adiponectin) added to the base model (T2DM) improved the relative IDI by 12.6 % for increased CD31+/annexin V+ EMPs to CD62E+ EMPs ratio.

CONCLUSION

We found that patients with T2DM and MetS may be distinguished by predominantly appearing phenotypes of circulating EMPs associated with pro-inflammatory cytokine overproduction. Elevated CD31+/annexin V+ EMPs to CD62E+ EMPs ratio is an indicator of impaired immune phenotype of EMPs, which allows determining the pattern of EMPs in dysmetabolic disorder patients.

Extracellular vesicles as new pharmacological targets to treat atherosclerosis

Extracellular vesicles released by most cell types, include apoptotic bodies (ABs), microvesicles (MVs) and exosomes. They play a crucial role in physiology and pathology, contributing to "cell-to-cell" communication by modifying the phenotype and the function of target cells. Thus, extracellular vesicles participate in the key processes of atherosclerosis from endothelial dysfunction, vascular wall inflammation to vascular remodeling. The purpose of this review is to summarize recent findings on extracellular vesicle formation, structure, release and clearance. We focus on the deleterious and beneficial effects of extracellular vesicles in the development of atherosclerosis. The potential role of extracellular vesicles as biomarkers and pharmacological targets, their innate therapeutic capacity, or their use for novel drug delivery devices in atherosclerotic cardiovascular diseases will also be discussed.

Central role of eNOS in the maintenance of endothelial homeostasis

SIGNIFICANCE

Disruption of endothelial function is considered a key event in the development and progression of atherosclerosis. Endothelial nitric oxide synthase (eNOS) is a central regulator of cellular function that is important to maintain endothelial homeostasis.

RECENT ADVANCES

Endothelial homeostasis encompasses acute responses such as adaption of flow to tissue's demand and more sustained responses to injury such as re-endothelialization and sprouting of endothelial cells (ECs) and attraction of circulating angiogenic cells (CAC), both of which support repair of damaged endothelium. The balance and the intensity of endothelial damage and repair might be reflected by changes in circulating endothelial microparticles (EMP) and CAC. Flow-mediated vasodilation (FMD) is a generally accepted clinical read-out of NO-dependent vasodilation, whereas EMP are upcoming prognostically validated markers of endothelial injury and CAC are reflective of the regenerative capacity with both expressing a functional eNOS. These markers can be integrated in a clinical endothelial phenotype, reflecting the net result between damage from risk factors and endogenous repair capacity with NO representing a central signaling molecule.

CRITICAL ISSUES

Improvements of reproducibility and observer independence of FMD measurements and definitions of relevant EMP and CAC subpopulations warrant further research.

FUTURE DIRECTIONS

Endothelial homeostasis may be a clinical therapeutic target for cardiovascular health maintenance.

Cardiac endothelium-myocyte interaction: clinical opportunities for new heart failure therapies regardless of ejection fraction

Heart failure (HF) is an important global health problem with great socioeconomic burden. Outcomes remain sub-optimal. Endothelium-cardiomyocyte interactions play essential roles in cardiovascular homeostasis, and deranged endothelium-related signalling pathways have been implicated in the pathophysiology of HF. In particular, disturbances in nitric oxide (NO)-mediated pathway and neuregulin-mediated pathway have been shown to contribute to the development of HF. These signalling pathways hold the potential as pathophysiological targets for new HF therapies, and may aid in patient selection for future HF trials.

Role of microparticles in endothelial dysfunction and arterial hypertension

Microparticles are small cell vesicles that can be released by almost all eukaryotic cells during cellular stress and cell activation. Within the last 1-2 decades it has been shown that microparticles are useful blood surrogate markers for different pathological conditions, such as vascular inflammation, coagulation and tumour diseases. Several studies have investigated the abundance of microparticles of different cellular origins in multiple cardiovascular diseases. It thereby has been shown that microparticles released by platelets, leukocytes and endothelial cells can be found in conditions of endothelial dysfunction, acute and chronic vascular inflammation and hypercoagulation. In addition to their function as surrogate markers, several studies indicate that circulating microparticles can fuse with distinct target cells, such as endothelial cells or leukocyte, and thereby deliver cellular components of their parental cells to the target cells. Hence, microparticles are a novel entity of circulating, paracrine, biological vectors which can influence the phenotype, the function and presumably even the transcriptome of their target cells.

This review article aims to give a brief overview about the microparticle biology with a focus on endothelial activation and arterial hypertension. More detailed information about the role of microparticles in pathophysiology and disease can be found in already published work.

Extracellular vesicles as therapeutic tools in cardiovascular diseases

Extracellular vesicles (EVs), including microvesicles (MVs) and exosomes, are small vesicles secreted from a wide variety of cells. Whereas MVs are particles released by the outward budding of the plasma membrane, exosomes are derived from endocytic compartments. Secretion of EVs can be enhanced by specific stimuli, and increased plasma circulating levels of EVs have been correlated with pathophysiological situations. MVs, already present in the blood of healthy individuals, are considerably elevated in several cardiovascular diseases associated with inflammation, suggesting that they can mediate deleterious effects such as endothelial dysfunction or thrombosis. Nonetheless, very recent studies also demonstrate that MVs may act as biological information vectors transferring proteins or genetic material to maintain cell homeostasis, favor cell repair, or even promote angiogenesis. Additionally, exosomes have also been shown to have pro-angiogenic and cardio-protective properties. These beneficial effects, therefore, reveal the potential therapeutical use of EVs in the field of cardiovascular medicine and regenerative therapy. In this review, we will provide an update of cellular processes modulated by EVs of specific interest in the treatment of cardiovascular pathologies. A special focus will be made on the morphogen sonic hedgehog (Shh) associated with EVs (EVs^Shh+), which have been shown to mediate many pro-angiogenic effects. In addition to offer a potential source of cardiovascular markers, therapeutical potential of EVs reveal exciting opportunities to deliver specific agents by non-immunogenic means to cardiovascular system.