High levels of circulating endothelial microparticles in patients with acute coronary syndromes

Background

Endothelial injury plays a critical role in coronary artery disease (CAD), but the assessment of this injury has been problematical. Recently, it has been shown in vitro that endothelial cells (ECs) release endothelial microparticles (EMPs) on activation or apoptosis and that an assay of EMPs can provide useful information on EC status in patients with thrombotic disorders. This study is aimed at assessing possible correlations between EMPs, which are markers of endothelial injury, and clinical subgroups of patients with CAD.

Methods

A prospective, case-controlled study was conducted on 84 patients with CAD and 42 control subjects to investigate EMP profiles. Included were 64 patients with acute coronary syndromes ([ACS], 38 with myocardial infarction [MI] and 26 with unstable angina [UA]) and 20 patients with stable angina (SA). EMPs in platelet-poor plasma were measured flow cytometrically with combinations of fluorescent antibodies (anti-CD31, -51, -42), allowing distinction of EMPs from platelet microparticles (PMPs). Clinical subgroups of patients were correlated with EMP and PMP levels in blood.

Results

Two species of EMPs (CD31+ and CD51+) were evaluated. Both were significantly higher in patients with CAD than in control subjects. CD31+ EMP was higher in ACS than SA. Among patients with first MI, CD31+ EMP was higher in patients with MI than in patients with UA and was significantly higher than in patients with recurring MI. CD51+ EMP did not discriminate ACS from SA. A simultaneous assay of PMP showed correlation between EMPs and PMPs. However, PMPs did not discriminate patients with SA from control subjects.

Conclusions

EMP assay appears promising for assessing EC injury in CAD.     

Endothelial microparticles and platelet and leukocyte activation in patients with the metabolic syndrome

Accumulating evidence has shown a strong association between the metabolic syndrome (MS) and a chronic inflammatory state predisposing to atherosclerosis. We investigated leukocyte, platelet, and endothelial activation markers and cellular interactions in 33 patients with the MS and 25 healthy controls. Using flow cytometry, we measured: (1)P-selectin expression in platelets; (2) platelet microparticles identified by CD31 expression; (3) endothelial microparticles (EMPs) identified by expression of CD31 (EMP(31)), CD62E (EMP(62E)), and CD51 (EMP(51)); (4) conjugates of leukocytes with platelet microparticles/platelets and with EMPs identified by CD54 (EMP(54)); and (5) CD11b expression in leukocytes. Patients with the MS had markedly elevated EMP(31), although EMP(62E) levels were normal, suggesting that EMP(31) levels were increased because of endothelial cell apoptosis, rather than activation. EMP(51), EMP(54)-lymphocyte conjugates, platelet expression of P-selectin, CD11b expression in leukocytes, and platelet-lymphocyte conjugates were also increased in patients with the MS. Platelet-leukocyte conjugates correlated with leukocyte activation, suggesting that platelet binding to leukocytes regulates leukocyte activation in vivo. In conclusion, our data demonstrate endothelial cell microparticle release, platelet and leukocyte activation, and increased binding of EMPs and platelets to leukocytes in patients with the MS.     

肿瘤坏死因子促进内皮细胞微颗粒释放的实验研究

目的研究肿瘤坏死因子损伤人脐静脉内皮细胞促进内皮细胞微颗粒释放,提出内皮细胞微颗粒是反映内皮损伤和功能障碍的新指标。方法应用肿瘤坏死因子-α刺激人脐静脉内皮细胞,扫描电镜观察细胞表面形态及内皮细胞微颗粒的生成,应用流式细胞仪检测细胞培养液中血小板细胞黏附分子(CD31+)和玻连蛋白(CD51+)微颗粒的水平。结果扫描电镜观察到静息状态下内皮细胞生成的微颗粒较少,经肿瘤坏死因子-α刺激24h后内皮细胞表面呈“出疹样”改变,小泡数目明显增多,直径大小约1.0μm。流式细胞仪检测证实细胞培养液中肿瘤坏死因子-α刺激组较正常对照组内皮细胞微颗粒水平明显增高[CD31+内皮细胞微颗粒,(164±63)/1000内皮细胞比(42±10)/1000内皮细胞,P<0.05;CD51+内皮细胞微颗粒,(260±108)/1000内皮细胞比(19±4)/1000内皮细胞,P<0.05]。结论肿瘤坏死因子损伤内皮细胞导致内皮细胞微颗粒释放增多,内皮细胞微颗粒有望成为评估内皮损伤替代指标之一。     

C-Reactive protein-induced endothelial microparticle generation in HUVECs is related to BH4-dependent NO formation

BACKGROUND: C-reactive protein (CRP) has been proven to facilitate endothelial injury via reduced NO production. Endothelial microparticles (EMPs) have emerged as a novel marker of endothelial injury. METHODS: In vitro cultured human umbilical vein endothelial cells (HUVECs) were incubated with CRP (20 mg/l) for 24 h. The numbers of EMPs with CD31- and CD51-positive staining were assessed flow-cytometrically, and NO production was measured using the Griess reaction in the presence or absence of tetrahydrobiopterin (BH(4)), respectively. RESULTS: The number of EMPs was significantly increased in HUVECs stimulated by CRP compared with the control group and, in parallel, NO production was decreased (p < 0.05). In the presence of CRP, pretreatment with BH(4) decreased EMP counts and restored NO production to baseline levels (p < 0.05) while pretreatment with 2,4-diamino-6-hydroxypyrimidine (DAHP), a BH(4) synthesis inhibitor, further prompted EMP formation and decreased NO production (p < 0.05). However, adding exogenous BH(4) after pretreatment with DAHP suppressed EMP formation and restored NO production (p < 0.05). CONCLUSIONS: This study demonstrates that CRP induces EMP generation in HUVECs and this effect is, at least in part, related to impaired BH(4)-dependent NO production. Augmented EMP generation in HUVECs is suggested as a novel potential mechanism contributing to the pathogenesis of vascular injury related to CRP.     

Elevated endothelial microparticles in thrombotic thrombocytopenic purpura: findings from brain and renal microvascular cell culture and patients with active disease

Endothelial injury is believed to be a key initiating event in the pathogenesis of thrombotic thrombocytopenic purpura (TTP), leading to platelet activation and formation of platelet-rich thrombi in microvasculature. However, the nature of endothelial injury in TTP is poorly defined and clinical assays to rapidly and reliably monitor endothelial damage are not readily available. Using flow cytometry, we measured endothelial microparticles (EMPs) generated from cultured renal and brain microvascular endothelial cells (MVECs) during activation and apoptosis, and evaluated the effect of TTP plasma on them. EMPs were measured using positivity for monoclonal antibodies (mAbs) CD31 and CD51, and their procoagulant activity was assessed using a Russell viper venom assay. Both cell lines generated procoagulant EMPs when cultured with inducers of activation (tumour necrosis factor alpha; TNF-alpha) or apoptosis (mitomycin C). TTP plasma induced a five- to sixfold increase of EMP generation and a two- to threefold increase of procoagulant activity in cultured brain and renal MVECs. TTP plasma induced a threefold and 13-fold increase of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression, respectively, on renal MVECs. Procoagulant activity tended to parallel EMP numbers. The effect of TTP plasma on cell viability was similar to that of TNF-alpha, implying that it induced activation rather than apoptosis. Control plasma and idiopathic thrombocytopenic purpura (ITP) plasma had little effect. In the clinical study, EMP assay of blood from acute TTP patients showed levels markedly elevated compared with normal controls, but values returned to normal in remission. In conclusion, TTP plasma activated and induced injury to MVECs in culture, judged by production of EMP and expression of activation markers. Released procoagulant EMP may play a role in the pathogenesis of TTP. Assay of EMP may be a useful marker of disease activity and endothelial injury in TTP and possibly other thrombotic disorders.     

内皮微粒与急性心肌梗死严重程度和预后的相关性

目的 探讨内皮微粒（EMP）与急性心肌梗死（AMI）严重程度及预后之间的相关性。 方法 入组AMI患者90例，根据Gensini积分分为2组:轻度病变组（n = 48）和严重病变组（n = 42）。对AMI患者随访一年，根据预后情况分为2组:预后良好组（n=23）和预后不良组（发生不良心血管事件者，n = 67）。流式微球技术检测血浆EMP，分析EMP与冠脉病变严重程度及预后的相关性。 结果 冠脉病变程度不同的两组间EMP、左室射血分数（LVEF）、无复流发生比例均有显著差别；EMP、无复流、LVEF是与冠脉病变严重程度相关的独立因素；对AMI患者随访1年左右，发现预后不良组LVEF值更低、EMP值更高、Genesini积分更高、3支病变及无复流现象更常见，3支病变、EMP、Gensini积分、LVEF、无复流是AMI预后不良的独立相关因素。 结论 EMP在评价AMI冠脉严重程度、冠脉血流恢复情况及预测患者预后方面具有一定的临床意义。     

急性冠脉综合征患者D31阳性CD42阴性内皮微粒的检测及其临床意义

目的 研究血浆CD31阳性CD42阴性的细胞微粒（CD-31 CD-42EMP）能否作为急性冠状动脉综合征患者危险程度的标志物.方法 收集62例急性冠脉综合征和62例稳定型冠心病患者及62例健康志愿者的血浆,用流式细胞术测定CD＋31 CD-42EMP水平,同时测定血浆超敏C-反应蛋白的水平.结果 与健康志愿者组比较,稳定型冠心病组患者CD＋31 CD-42EMP水平和超敏C-反应蛋白的水平明显升高,差异有显著性;与稳定型冠心病组患者及健康志愿者组比较,急性冠脉综合征组患者的CD＋31 CD-42EMP水平和超敏C-反应蛋白的水平明显升高,差异具有显著性.结论 CD＋31 CD-42EMP水平能作为急性冠脉综合征危险程度的标志物,且与超敏C-反应蛋白的水平有明显相关性.     

Digoxin use is associated with increased platelet and endothelial cell activation in patients with nonvalvular atrial fibrillation.

OBJECTIVES: The purpose of this study was to determine whether digoxin use is associated with increased flow cytometric markers of endothelial cell and platelet activation in patients with nonvalvular atrial fibrillation (AF). BACKGROUND: Increased intracellular calcium is a key event in platelet activation, and several studies have demonstrated that digitalis activates platelets in vitro. Intracellular calcium also is a key regulator of endothelial cell function, and endogenous digitalis-like substances have been shown to affect biologic processes in endothelial cells. METHODS: We studied 30 patients with nonvalvular AF. We measured the levels of (1) platelet expression of P-selectin (CD62P), (2) platelet microparticles (PMP); and (3) endothelial microparticles (EMP) identified by anti-CD31 (EMP31) and by anti-E-selectin antibodies (EMP62E). RESULTS: Patients who were taking digoxin (n = 16; mean digoxin level = 0.93 ng/dL) did not demonstrate any significant differences in clinical or echocardiographic characteristics compared with patients not taking digoxin (n = 14). Patients taking digoxin had significantly increased levels of CD62P expression in platelets and platelet-leukocyte conjugates and markedly increased markers of endothelial activation: EMP62E and EMP31. After adjusting for potential confounders (including age, congestive heart failure, coronary artery disease, ejection fraction, antiplatelet, beta-blocker, and calcium channel blocker use), the differences persisted. CONCLUSIONS: Digoxin use in patients with AF is associated with increased levels of endothelial and platelet activation. If digitalis activates endothelial cells and platelets at pharmacologic doses, use of digitalis in conditions such as AF could predispose to thrombosis and vascular events.     

Endothelial and platelet microparticles in vasculitis of the young

OBJECTIVE: Microparticles are released from endothelial cells in response to a variety of injurious stimuli and recently have been shown to be increased in a number of diseases associated with endothelial dysfunction. This study examined endothelial microparticle (EMP) and platelet microparticle (PMP) profiles in children with systemic vasculitis to test the hypothesis that EMPs may provide a noninvasive means of examining endothelial activation or injury. METHODS: The study cohort comprised 39 children with systemic vasculitis at various stages of disease activity, 24 control children with febrile disease, and a control group of 43 healthy subjects. Plasma was ultracentrifuged at 17,000g for 60 minutes, and the microparticle pellets were examined using flow cytometry. RESULTS: Plasma from patients with active systemic vasculitis contained significantly higher numbers of E-selectin-positive EMPs compared with that from patients in remission, healthy controls, or febrile disease controls (P = 0.000 for each). A similar result was obtained for the numbers of EMPs expressing the marker CD105. There was also a significant increase in PMPs expressing CD42a in the active vasculitis group as compared with the other groups, but this difference was not significant for PMPs expressing P-selectin. The EMP counts correlated with the Birmingham Vasculitis Activity Score and the acute-phase reactant levels in the patients with systemic vasculitis, but there was a poor correlation overall between EMP counts and the acute-phase reactant levels in the febrile disease controls. CONCLUSION: EMPs may provide a window to the activated endothelium and could provide important pathophysiologic insights into the vascular injury associated with vasculitis of the young.     

Imbalance between endothelial injury and repair in patients with polymyalgia rheumatica: improvement with corticosteroid treatment

Abstract. Pirro M, Bocci EB, Di Filippo F, Schillaci G, Mannarino MR, Bagaglia F, Gerli R, Mannarino E (From the Unit of Internal Medicine, Angiology and Arteriosclerosis, Department of Clinical and Experimental Medicine; Division of Rheumatology, Department of Clinical and Experimental Medicine, University of Perugia, Perugia, Italy). Imbalance between endothelial injury and repair in patients with polymyalgia rheumatica: improvement with corticosteroid treatment. J Intern Med 2012; 272 : 177–184. Objectives. Polymyalgia rheumatica (PMR) is a rheumatic disease that is characterized by intense activation of systemic inflammation. Systemic inflammation has been associated with an imbalance between endothelial injury and repair, defined by an increased number of circulating endothelial microparticles (EMPs) and a reduced number of endothelial progenitor cells (EPCs). We investigated the association between inflammation and endothelial injury and repair in patients with PMR and evaluated the effects of corticosteroid therapy on EMP and EPC levels. Design, setting and subjects. We conducted a case–control study in 34 patients with never‐treated active PMR and 34 healthy age‐ and sex‐matched controls. Patients with PMR participated in a 1‐month intervention open‐label study with corticosteroid therapy. Circulating EMPs (CD31+/CD42?) and EPCs (CD34+/KDR+) were quantified by fluorescence‐activated cell sorting analysis. Results. Patients with PMR had an increased EMP/EPC ratio compared with controls [median (IQR): 6.5 (3.0–11.5) vs. 1.1 (0.7–1.5), P < 0.001], because of both increased EMP and reduced EPC levels. Levels of C‐reactive protein (CRP) were associated with an increased EMP/EPC ratio (β = 0.48, P = 0.001), irrespective of traditional cardiovascular risk factors. Corticosteroid therapy led to a significant CRP reduction [from 3.9 (1.5–6.7) to 0.6 (0.2–1.2) mg dL^?1, P < 0.05], paralleled by a consistent 81% decline in the EMP/EPC ratio. CRP and EMP/EPC ratio reductions were significantly correlated (rho = 0.37, P = 0.04). Conclusions. Polymyalgia rheumatica is associated with a significant imbalance between endothelial injury and repair, which is dependent on the degree of systemic inflammation. Attenuation of inflammation by short‐term corticosteroid therapy might have a role in limiting endothelial fragmentation and promote endothelial repair.     

内皮微粒与冠心病相关性研究

目的:探讨血浆内皮微粒(EMP)与冠心病的相关性。方法:冠心病组367例,其中稳定型心绞痛(SA)119例,急性冠状动脉综合征(ACS)248例,后者含不稳定型心绞痛(UA)158例,急性心肌梗死(AMI)90例。非冠心病组166例。ELISA法测定血浆ET-1,流式微球技术检测血浆EMP。结果:冠心病组ET-1、EMP水平升高,呈正相关(r=0.233,P=0.001)。ACS组EMP(547.405)显著高于非冠心病组(148.185)及SA组(429.890),亚组分析中UA组EMP(551.660)升高最为显著;冠心病冠状动脉病变支数与EMP无明显相关;AMI患者EMP与BNP、TnT、TnI间无明显相关;EMP与ACS患者短期预后相关(r=0.280,P<0.01)。结论:血浆EMP水平可反映冠心病内皮功能障碍,与冠心病的发生、冠状动脉斑块的不稳定性有关。     

急性冠状动脉综合征患者外周血CD31~(bright)/Annexin V~+内皮微粒水平增高

目的 观察急性冠状动脉综合征患者与非冠心病患者外周血内皮微粒水平,探讨CD31bright/AnnexinV+内皮微粒与心血管危险因素的相关性.方法 急性冠状动脉综合征患者56例,非冠心病患者26例,采用流式细胞仪检测外周血CD31bright/Annexin V+内皮微粒水平.结果 与非冠心病患者比较,急性冠状动脉综合征患者外周血CD31bright/Annexin V+内皮微粒显著增加(P<0.01),而急性心肌梗死与不稳定型心绞痛亚组之间外周血CD31bright/Annexin V+内皮微粒水平无显著性差异(P>0.05).所有入选患者中,2型糖尿病患者外周血CD31bright/Annexin V+内皮微粒水平较非糖尿病患者显著升高(P<0.05);多因素回归分析显示,血清甘油三酯水平与外周血CD31bright/Annexin V+内皮微粒数量独立正相关(r=0.28,P<0.05).急性冠状动脉综合征组血清高敏C反应蛋白水平与外周血CD31bright/Annexin V+内皮微粒数量呈正相关(r=0.31,P<0.05).结论 急性冠状动脉综合征患者和糖尿病患者外周血CD31bright/Annexin V+内皮微粒增多,提示急性冠状动脉综合征患者和2型糖尿病患者内皮损伤严重.CD31bright/Annexin V+内皮微粒水平增高可能与血清甘油三酯和血清高敏C反应蛋白水平增高有关.     

Association between plasma endothelial microparticles and contrast-induced nephropathy in patients underwent coronary angiography

We aim to investigate the association between plasma endothelial microparticles (EMPs) and contrast-induced nephropathy of patients underwent coronary angiography.The patients were divided into normal renal function group and renal dysfunction group based on the estimated glomerular filtration rate (eGFR). Among the 180 cases, 117 received determination of EMP and serum creatinine after percutaneous coronary intervention (PCI) and/or coronary angiography. The patients were divided into contrast-induced-nephropathy (CIN) group and non-CIN group. EMPs collection and determination were performed, together with biochemical analysis and digital subtraction angiography (DSA) analysis.Spearman correlation showed that the expression of EMP was negatively correlated with eGFR (r = –0.201, P < .01). The serum hypersensitive C-reactive protein (hs-CRP), cystatin C (Cys-C), uric acid (UA) were significantly higher in CIN group than that in the non CIN group. Spearman correlation showed that the expression of EMP was positively correlated with serum interleukin-6 (IL-6, r = 0.393, P < .01). The expression of EMP was positively correlated with serum hs-CRP (r = 0.360, P < .01). Logistic regression analysis showed that the levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), eGFR, UA, and Cys-C were correlated with the incidence of contrast induced nephropathy.In patients with contrast-induced-nephropathy, the plasma EMPs were significantly increased after coronary angiography. The expression of plasma EMPs may play a role in the occurrence of contrast-induced-nephropathy.     

Effects of pioglitazone versus metformin on circulating endothelial microparticles and progenitor cells in patients with newly diagnosed type 2 diabetes--a randomized controlled trial

Aim: Endothelial microparticles (EMPs) and endothelial progenitor cells (EPCs) are markers of endothelial injury and repair. We compared the effects of pioglitazone versus metformin on the circulating numbers of EMPs and EPCs in patients with newly diagnosed type 2 diabetes. Methods: This was a randomized, double‐blind, comparator‐controlled, 24‐week single‐centre trial conducted in a Teaching Hospital in Naples, Italy. One hundred and ten people with newly diagnosed type 2 diabetes who were never treated with antihyperglycaemic drugs and had haemoglobin A1c (HbA1c) levels between 7 and 10% were given pioglitazone hydrochloride (15–45 mg/day) (n = 55) or metformin (1000–2000 mg/day) (n = 55) as an active comparator. Absolute change from baseline to final visit in circulating EMPs and EPCs and their ratio were the main outcomes. Results: Baseline characteristics did not differ between the study groups. The decrease in circulating EMPs CD31+ [intergroup difference, ?32 counts/µl (95% CI ?51 to ?9)] and the increase in EPCs CD34+/KDR+ [intergroup difference, 33 cells/10⁶ events (95% CI 13 to 55)] were greater with pioglitazone versus metformin. EMPs/EPCs ratio was reduced with pioglitazone and unchanged with metformin [difference, ?1.5 (95% CI ?2.6 to ?0.5), p < 0.001]. Participants assigned to pioglitazone gained more weight and experienced greater improvements in some coronary risk measures [high‐density lipoprotein (HDL)‐cholesterol, triglycerides, adiponectin and C‐reactive protein (CRP)] than did those assigned to metformin. Conclusion: Compared with metformin, pioglitazone treatment improved the imbalance between endothelial damage and repair capacity and led to more favourable changes in coronary risk factors in patients with newly diagnosed type 2 diabetes.     

Circulating endothelial microparticles involved in lung function decline in a rat exposed in cigarette smoke maybe from apoptotic pulmonary capillary endothelial cells

Background

Plasma levels of endothelial microparticles (EMPs), small membrane vesicles, shed from activated or apoptotic endothelial cells are elevated in patients with COPD and in smokers with normal lung function. Whether plasma EMPs levels are elevated in a rat exposed in cigarette smoke, whether the elevated EMPs derived from pulmonary endothelial cell apoptosis, and the relationship between EMP and lung function are obscure.

Methods

All 60 wister rats were divided into six groups, three groups of ten rats were exposed to cigarette smoke of ten non-filter cigarettes per day, 5 days a week, using a standard smoking machine (Beijing BeiLanBo Company, China) for a period of 2, 4 and 6 months (n=10, respectively). Age-matched three control groups were sham-smoked. Pulmonary function parameters, including the ratio of forced expiratory volume in 0.3 second over forced vital capacity (FEV0.3/FVC) and dynamic compliance (Cdyn), were tested at the end of each period (2, 4, 6 months). Blood samples were collected and platelet-free plasma was isolated. Then CD42b–/CD31+ EMPs were analysed by flow cytometry. In parallel, lungs were removed and Colocalization with terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL), Hoeschts and CD31 was performed to evaluate pulmonary capillaries-specific apoptosis and identify the origins of the EMPs.

Results

At 2, 4 and 6 months, in comparison with control groups, rats in cigarette smoke exposed groups had a significant increase in CD42b–/CD31+ EMPs (P<0.001, P<0.001, P<0.001, respectively), and Pulmonary function indicated that FEV0.3/FVC (P<0.05, P<0.01, P<0.01, respectively) and Cdyn (P<0.01, P<0.001, P<0.001 respectively) decreased. At the same time, CD42b–/CD31+ EMP counts were negatively correlated with Cdyn (P<0.05). Moreover, in vivo, TUNEL-positive cells co-localized with CD31 in whole lung tissue demonstrated a sequence of apoptosis signal in the cigarette smoke exposed groups.

Conclusions

CD42b–/CD31+ EMPs may be a potential biomarker for indicating the severity of impairment of pulmonary function in the rats exposed cigarette smoke. The increased EMPs may derive from pulmonary capillaries-specific apoptosis.     

Correlation between apoptotic endothelial microparticles and serum interleukin-6 and C-reactive protein in healthy men

Inflammation has been associated with increased cardiovascular risk, and endothelial cell (EC) apoptosis has been implicated in atherogenesis. The correlation between circulating concentrations of interleukin-6 (IL-6), C-reactive protein (CRP), and endothelial microparticles (EMPs) expressing an apoptotic (EMP31) or activation (EMP62E) phenotype in 20 middle-aged healthy men was investigated. IL-6 was significantly correlated with EMP31 (r = 0.6, p = 0.004), which persisted after adjusting for body mass index and CRP. CRP was significantly correlated with body mass index (r = 0.49, p = 0.02) but not with EMP31 or EMP62E. EC apoptosis is associated with IL-6 levels in men and might be partially responsible for the increased cardiovascular risk associated with subclinical inflammation.     

Circulating endothelial microparticles in children with Henoch�CSch?nlein purpura; preliminary results

The aim of this study was to investigate the levels of circulating endothelial microparticles (EMPs) in children with HSP and to determine whether there was a difference between patients with nephritis and those without nephritis. Twenty patients with HSP aged between 2.5 and 15 and 10 age-and sex-matched healthy controls were enrolled in the study. The HSP group was divided into two groups, including patients with nephritis (n = 9) and those without nephritis (n = 11). In all groups, circulating EMPs were enumerated by flow cytometry, after staining platelet-free plasma with PE-conjugated anti-CD144. At the same time, human umbilical vein endothelial cells (HUVEC) were incubated with the platelet-free plasma of patients with HSP and that of the control group. Then, circulating EMPs were counted in HUVEC supernatant incubated with the platelet-free plasma of patients and control groups, after staining the supernatant with PE-conjugated anti-CD146. Circulating EMPs were significantly higher in both the active and the remission period of the patient groups compared with the control subjects. In the patient group, there were no statistically significant differences in the level of circulating EMPs between patients with nephritis and those without nephritis. Both CD144 and 146+EMP in patients with HSP nephritis in the active period were substantially higher than in those remissions. CD144+EMP in the active period were substantially higher than in the remission period in patients without nephritis. We detected that circulating EMPs increased in patients with HSP in both active and remission periods. Although clinical and laboratory findings return to normal in the remission period, the increased circulating EMPs may show that the subclinical inflammatory process is continuous. We think that circulating EMPs could be used as a surrogate marker for subclinical inflammation in HSP.     

Elevated levels of VE-cadherin-positive endothelial microparticles in patients with type 2 diabetes mellitus and coronary artery disease

OBJECTIVES: The purpose of this study was to examine whether CD144-EMP (endothelium-derived microparticles) is useful as a specific marker of endothelial cell (EC) dysfunction and to determine whether plasma levels of circulating CD144-EMP predicted coronary artery disease (CAD) in patients with type 2 diabetes mellitus (DM). BACKGROUND: Endothelial cell dysfunction is involved in atherogenesis; however, the quantitative assessment of EC dysfunction has yet to be established clinically. Endothelium-derived microparticles are small, membrane-shed vesicles that are generated from the EC surface in response to cellular dysfunction and/or injury. Diabetes mellitus is known to be associated with EC dysfunction and accelerated atherosclerosis. METHODS: We characterized EMP using anti-CD144 (VE-Cadherin) antibody in various atherosclerosis-related cells and investigated the association between the levels of CD144-positive microparticles and hydrogen-peroxide-induced EC injury and acetylcholine-induced coronary vasomotion. Furthermore, we evaluated plasma CD144-EMP levels in patients with and without DM. RESULTS: We demonstrated that CD144-positive microparticles were derived selectively from human EC. The levels of CD144-EMP reflected the degree of in vitro hydrogen-peroxide-induced EC injury and impairment of in vivo endothelium-dependent coronary vasodilation (p < 0.01). Plasma CD144-EMP levels were increased significantly in DM patients compared with patients without DM (p < 0.001). In DM patients, the elevated levels of CD144-EMP were the most significant risk factor for CAD relative to all other traditional risk factors (odds ratio [OR] 3.5, 95% confidence interval [CI] 1.8 to 6.9, p < 0.001). Notably, plasma CD144-EMP identified a subpopulation of established CAD patients in DM subjects without typical anginal symptoms (OR 10.6, 95% CI 3.9 to 29.5, p < 0.001). CONCLUSIONS: The CD144-positive EMP exist in human plasma, and plasma CD144-EMP levels can be a clinically specific and quantitative marker of EC dysfunction and/or injury. Measurement of CD144-EMP, by providing a quantitative assessment of EC dysfunction, may be useful for identifying DM patients with increased risk of CAD.     

Endothelial microparticles correlate with endothelial dysfunction in obese women

CONTEXT: Cell-derived microparticles are supposed to be involved in atherogenesis. OBJECTIVE: This study aimed to evaluate circulating microparticles in obese women and their relation with anthropometric measures and endothelial dysfunction. DESIGN, SETTING, AND PARTICIPANTS: Forty-one obese [body mass index (BMI) > 30 kg/m(2)] women and 40 normal weight (BMI < 25 kg/m(2)) age-matched women were studied. Flow cytometry was used to assess microparticles by quantification of circulating endothelial microparticles (EMP, CD31+/CD42b-) and platelet microparticles (PMP, CD31+/CD42b+) in peripheral blood; endothelium-dependent flow-mediated vasodilation (FMD) was evaluated in the right brachial artery after reactive hyperemia. RESULTS: Compared with lean women, obese women presented significantly higher numbers of EMP and PMP, and reduced FMD. BMI did not correlate with either EMP (r = 0.02, P = 0.9) or PMP (r = -0.07, P = 0.645), whereas waist-to-hip ratio (WHR) showed significant correlation with both microparticles (r = 0.699, P < 0.001; r = 0.373, P = 0.016, respectively). Both EMP and PMP counts positively correlated with impairment of FMD in obese women. Multivariate analysis correcting for age, anthropometric indices, lipid parameters, and PMP identified EMP as the only independent predictor for impaired endothelial-dependent vasodilation (P = 0.003). CONCLUSIONS: EMP are elevated in obese women and independently involved in the pathogenesis of endothelial dysfunction. WHR is the anthropometric measure more closely related to EMP and endothelial dysfunction.     

Interaction of endothelial microparticles with monocytic cells in vitro induces tissue factor-dependent procoagulant activity

In the present study we investigated whether endothelial microparticles (EMPs) can bind to monocytic THP-1 cells and modulate their procoagulant properties. Using flow cytometry, we demonstrated that EMPs express adhesive receptors similar to those expressed by activated endothelial cells. Expression of endothelial antigens by THP-1 cells incubated with EMP was shown by immunoperoxidase staining and flow cytometry using antibodies directed against E-selectin, VCAM-1, and endoglin. EMP binding to THP-1 cells was time- and concentration- dependent, reached a plateau at 15 minutes, and had an EMP-to-monocyte ratio of 50:1. EMP binding was not affected by low temperature and was not followed by the restoration of phosphatidylserine asymmetry, suggesting that adhesion was not followed by fusion. A 4-hour incubation of THP-1 cells with EMP led to an increase in procoagulant activity as measured by clotting assay. Concomitantly, THP-1 exhibited increased levels of tissue factor (TF) antigen and TF mRNA compared to control cells. The ability of EMP to induce THP-1 procoagulant activity was significantly reduced when THP-1 cells were incubated with EMP in the presence of blocking antibodies against ICAM-1 and beta2 integrins. These results demonstrate that EMPs interact with THP-1 cells in vitro and stimulate TF-mediated procoagulant activity that is partially dependent on the interaction of ICAM-1 on EMP and its counterreceptor, beta2 integrins, on THP-1 cells. Induction of procoagulant activity was also demonstrated using human monocytes, suggesting a novel mechanism by which EMP may participate in the dissemination and amplification of procoagulant cellular responses.