Levels Of Endothelial Microparticles Research Articles

Effects of tirofiban on platelet activation and endothelial function in patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention.

This pilot study examined, for the first time, the effect of intracoronary administration of tirofiban, an inhibitor of platelet aggregation, on platelet activation and endothelial dysfunction in patients with ST-segment-elevated myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI). A total of 119 STEMI patients were randomized into either tirofiban group (n = 72, intracoronary injection of 10 μg/kg tirofiban prior to PCI, followed by intravenous infusion at 0.15 μg/kg min) or a control group (n = 47), which did not receive tirofiban. Periprocedural administration of tirofiban was associated with significantly reduced levels of platelet activation (lower levels of CD62P and PAC-1) and endothelial dysfunction (reduced levels of endothelial microparticles, VCAM-1, and ICAM-1) 48 h after PCI. At 10 days after PCI, patients in the tirofiban group had a higher incidence of complete STR (78.7 vs. 65.0%) and higher left ventricular ejection fractions (47.8 vs. 44.2) compared to those in the control group. The clinical outcomes between two groups did not differ significantly two weeks after treatment. The results demonstrated that periprocedural administration of tirofiban is associated with significantly attenuated platelet activation and endothelial dysfunction in STEMI patients undergoing PCI. This may have contributed to the improved myocardial reperfusion and preservation of left ventricular systolic function in these patients.

Flow cytometric assessment of endothelial and platelet microparticles in preeclampsia and their relation to disease severity and Doppler parameters

ObjectivePlatelet (P) and endothelial (E) microparticle (MP) levels increase in preeclampsia. However, their relation to the severity of the disease needs to be clarified. The objectives of this study were to compare the levels of EMP and PMP in severe and mild preeclampsia to healthy gravidas to find possible correlations to severity of the disease, Doppler changes, and complications.MethodsA comparative prospective clinical trial (Canadian Task Force II-1) was conducted on 135 pregnant women divided into three groups: 35 women with severe preeclampsia (group 1), 40 with mild preeclampsia (group 2), and 60 healthy gravids (group 3). Assessment of EMP and PMP was done by flow cytometry using anti-CD31 and anti-CD42b antibodies.ResultsExpression of CD31 and CD42b (EMPs) was higher in group 1 compared to groups 2 and 3 with P < 0.001, while expression of CD42b alone (PMPs) did not show a statistically significant difference (P = 0.957). EMPs were correlated positively to umbilical and middle cerebral artery resistance index. There was a significant negative correlation between platelet count and EMPs. Also, EMPs were correlated positively to aspartate transferase and bilirubin levels and were significantly higher with neonatal death.DiscussionThe present study revealed a significant association between plasma levels of EMPs and severity of preeclampsia together with poor neonatal outcome as regards birth weight and percent of neonatal death. So, EMPs assay could be a good predictor of maternal and fetal outcomes and in cases with preeclampsia.

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

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. 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. 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. 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.

SAT0030 Circulating Endothelial Microparticles and Endothelial Progenitors Cells in Primary SjÖGren's Syndrome: New Markers of Chronic Endothelial Damage?

BackgroundSubclinical atherosclerosis can be considered a form of systemic involvement in patients with chronic inflammatory joint and connective tissue diseases. Multiple factors, including inflammatory and immune-mediated mechanisms, have been identified...

Effects of moderate aerobic exercise training on vascular health and blood pressure in African Americans.

As healthcare progresses toward individualized medicine, understanding how different racial groups respond to lifestyle interventions is valuable. It is established that African Americans have disproportionate levels of cardiovascular disease and impaired vascular health, and clinical practice guidelines suggest lifestyle interventions as the first line of treatment. Recently, the authors reported that 6months of aerobic exercise improved inflammatory markers, flow-mediated dilation (FMD), and levels of circulating endothelial microparticles (EMPs) in African American adults. This study is a subgroup analysis of the aerobic exercise-induced changes in vascular health and blood pressure (BP) measures, including carotid artery intima-media thickness (IMT), nitroglycerin-mediated dilation (NMD), ambulatory BP, and office BP. Sedentary African American adults (53.4±6.2years; 21 women and 5 men) showed improved vascular health but no change in BP. Carotid artery IMT decreased 6.4%, plasma nitric oxide levels increased 76.6%, plasma EMP levels decreased, percentage of FMD increased 59.6%, and FMD/NMD ratio increased 36.2% (P<.05 for all). Six months of aerobic exercise training is sufficient to elicit improvements in vascular structure and function in African Americans, even without improvements in BP measures or NMD (ie, smooth muscle function). To our knowledge, this is the first study to report such findings in African Americans.

Effects of high intensity training and high volume training on endothelial microparticles and angiogenic growth factors.

AimsEndothelial microparticles (EMP) are complex vesicular structures shed from activated or apoptotic endothelial cells. As endurance exercise affects the endothelium, the objective of the study was to examine levels of EMP and angiogenic growth factors following different endurance exercise protocols.Methods12 subjects performed 3 different endurance exercise protocols: 1. High volume training (HVT; 130 min at 55% peak power output (PPO); 2. 4×4 min at 95% PPO; 3. 4×30 sec all-out. EMPs were quantified using flow cytometry after staining platelet-poor-plasma. Events positive for Annexin-V and CD31, and negative for CD42b, were classified as EMPs. Vascular endothelial growth factor (VEGF), migratory inhibiting factor (MIF) and hepatocyte growth factor (HGF) were determined by ELISA technique. For all these measurements venous blood samples were taken pre, 0′, 30′, 60′ and 180′ after each intervention. Furthermore, in vitro experiments were performed to explore the effect of collected sera on target endothelial functions and MP uptake capacities.ResultsVEGF and HGF significantly increased after HIT interventions. All three interventions caused a significant decrease in EMP levels post exercise compared to pre values. The sera taken after exercise increased the uptake of EMP in target endothelial cells compared to sera taken under resting conditions, which was shown to be phosphatidylserin-dependent. Increased EMP uptake was associated with an improved protection of target cells against apoptosis. Sera taken prior and after exercise promoted target endothelial cell migration, which was abrogated after inhibition of VEGF.ConclusionPhysical exercise leads to decreased EMP levels and promotes a phosphatidylserin-dependent uptake of EMP into target endothelial cells, which is associated with a protection of target cells against apoptosis.

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

To examine the relation of endothelial microparticles (EMPs) with cardiometabolic risk in the community. Circulating EMPs are small membrane vesicles released after endothelial cell injury. Endothelial microparticles are reportedly increased among individuals with a high burden of cardiovascular risk factors. However, prior investigations have been limited to small, highly selected samples. We studied 844 individuals without a history of cardiovascular disease in the Framingham Offspring cohort (mean age 66 ± 9 years, 57% women). We used standardized flow cytometry methods to identify and quantify circulating CD144+ and CD31+/CD41- EMPs. We then used multivariable regression analyses to investigate the relations of EMP phenotypes with cardiovascular and metabolic risk factors. In multivariable analyses, the following cardiovascular risk factors were associated with one or more of the circulating EMP populations: hypertension (P = 0.025 for CD144+,), elevated triglycerides (P = 0.002 for CD144+, P < 0.0001 for CD31+/CD41-), and metabolic syndrome (P < 0.0001 for CD144+,). Overall, each tertile increase in the Framingham risk score corresponded to a 9% increase in log-CD31+/CD41- EMPs (P = 0.022). Furthermore, the presence of hypertriglyceridaemic waist status was associated with 38% higher levels of CD144+ EMPs (P < 0.0001) and 46% higher levels of CD31+/CD41- EMPs (P < 0.0001). In a large community-based sample, circulating EMP levels were associated with the presence of cardiometabolic risk factors, particularly dyslipidaemia. These data underscore the potential influence of high-risk metabolic profiles on endothelial integrity.

Circulating microparticles in migraine with aura: Cause or consequence, a link to stroke

Over the past three decades, epidemiological studies have firmly established migraine with aura as an important risk factor for ischemic stroke, particularly in young women (1), and those without conventional cardiovascular risk profiles (2). The discovery of migraine’s association with a number of other vascular conditions such as Raynaud’s phenomenon (3), variant angina (4), pre-eclampsia (5), and livedo reticularis (6), has fueled speculation for a pivotal role of the endothelium in migraine pathogenesis and in migraineassociated stroke (7). The endothelium is an active endocrine organ, producing substances to maintain vascular and neural homeostasis (e.g. prostacyclin, endothelin-1, angiotensin II, and nitric oxide), while inactivating other vasoactive substances (e.g. serotonin and bradykinin). Endothelial dysfunction (ED) is characterized by impaired vascular reactivity and by endothelial activation. In migraine, reactivity studies have mostly focused on the peripheral vasculature, and findings are conflicting (8). Evidence of increased arterial stiffness, however, has been more uniform (9–12). Findings of a pro-inflammatory and procoagulatory milieu in migraine have been offered as indirect evidence of endothelial activation (13). Newer lines of investigation include the quantification of circulating endothelial progenitor cells, and each of three studies has demonstrated significant differences (either increased or decreased) between migraineurs and the control group (14–16). This has been interpreted as being related to increased need for endothelial repair. In their article ‘‘Circulating endothelial microparticles in female migraineurs with aura,’’ Liman and coauthors report a case-control study of a novel surrogate marker for endothelial activation in a small cohort of premenopausal women, the subgroup at highest risk of stroke (17). Microparticles (MPs) is the term for the submicron membrane vesicles released from different cell populations into the circulation in response to various stimuli (18). Although initially referred to as ‘‘cellular debris,’’ it is now recognized that the quality and quantity of circulating MPs carry a wealth of biological information (18,19). The specific protein and oxidized phospholipid composition of the MPs reveals both the cellular origin (e.g. platelets, monocytes, endothelial cells) as well as the underlying stimulus producing them (e.g. activation, injury, apoptosis). It is estimated that at least 70% of circulating MPs are derived from platelets with only 5% to 15% from endothelial cells (19). The quantity of MPs in the circulation increases across the spectrum from health to disease. The main finding from the study by Liman et al. (17) is that levels of endothelial MPs (EMPs) related to endothelial activation are elevated in young women with migraine with aura. Furthermore, the activated EMP levels positively correlate with the finger tonometry-derived augmentation index, a marker of arterial stiffness. Lastly, the authors report that levels of MPs from platelets (PMPs) and monocytes (MMPs) are also elevated in migraine, indicating a pro-inflammatory and hypercoagulable state. The implications of these findings as they pertain to migraine pathogenesis and stroke risk are best understood in the context of the literature. Cell culture studies demonstrate that EMPs are shed on exposure to inflammatory cytokines, such as interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF) alpha (18,19). Levels of these and other cytokines are elevated in the plasma of migraineurs between attacks (compared to healthy controls), and rise during attacks (compared to their interictal levels) (20–24). Interictal cytokine levels have been reported to correlate with migraine

Circulating endothelial microparticles in female migraineurs with aura

Endothelial microparticles (EMPs) are vesicles that are released from activated endothelial cells and serve as a surrogate for endothelial dysfunction (ED). ED may be involved in migraine pathophysiology and contribute to the increased risk of ischemic stroke, particularly in female migraineurs with aura (MA). We sought to determine whether EMPs are elevated in women with MA. In this case-control study, EMPs were detected by analysing surface markers using fluorescence-activated cell sorting (FACS). Surface markers were measured covering the main cell lines relevant in cardiovascular disease like endothelial cells, platelets, monocytes and leucocytes. Microparticles (MPs) were identified in correlation to calibration by 1 -µm calibrator beads (Beckman Coulter). Arterial stiffness was assessed using fingertip tonometry and the heart rate-adjusted augmentation index (AI). We included 29 patients with MA and 29 matched controls. MA patients had significantly higher EMPs (CD62E(+)AnnexinV(+): 5142/µl vs 1535/µl; p < 0.001; CD144(+)AnnexinV(+): 6683/µl vs 3107/µl; p < 0.001), monocytic (CD14(+)AnnexinV(+) 6378 vs 3161; p < 0.001), and platelet MPs (CD62P(+)CD42b(+)AnnexinV(+) 5450 vs 3204; p < 0.001). Activated EMPs (CD62E(+)AnnexinV(+)) correlated with heart-rate adjusted AI (r = 0.46; p < 001). EMP levels are significantly elevated in women with MA and correlated with increased AI. Our findings suggest that endothelial activation is present in women with MA. This might contribute to higher stroke risk in MA.

Angiotensin II receptor type 1 autoantibodies promote endothelial microparticles formation through activating p38 MAPK pathway

Endothelial microparticles (EMPs) are small vesicular structures that serve as a marker of endothelial function. Angiotensin II receptor type 1 autoantibody (AT1-AA) can cause endothelial dysfunction. However, whether AT1-AA promotes EMPs formation and the mechanism remains obscure. The titres of sera AT1-AA of 126 hypertensive patients and 30 normotensive individuals were evaluated by ELISA. EMPs in the sera and the supernatants of human umbilical vein endothelial cells (HUVECs) were measured by flow cytometry. The phosphorylation levels of mitogen-activated protein kinase (MAPK) pathways in HUVECs treated by AT1-AA were assessed and their correlation with microparticle formation was also analysed. Furthermore, the production of intracellular reactive oxygen species (ROS) and nitric oxide in HUVECs was examined after incubation with 'injured' endothelial microparticle (iEMPs) (EMPs derived from AT1-AA treated HUVECs). The positive rate of AT1-AA in 126 hypertensive patients was 21.4% (27/126), and higher than that in normotensive individuals [3.3% (1/30), P < 0.01]. Circulating EMP (CD31+/CD42b-) levels were corresponding to the AT1-AA titres in hypertensive group (r(2) = 0.3661, P < 0.01). AT1-AA promoted EMPs generation from HUVECs in a time and dose-dependent manner than the vehicle or nonspecific IgG. Meanwhile, AT1-AA significantly elevated phosphorylation level of P38 and ERK in HUVECs. Lorsartan and P38 inhibitor could suppress the AT1-AA's stimulation effect on EMPs generation. Moreover, the iEMP greatly increased ROS production and reduced nitric oxide synthesis in HUVECs. Our findings showed that circulating EMPs levels positively correlate to the serum AT1-AA titres in essential hypertension patients. The AT1-AA could promote EMPs generation in HUVECs through activation of P38 MAPK signalling pathway, and this effect could be effectively inhibited by losartan or p38 inhibitor. Angiotensin receptor blockers (ARBs) may be more suitable for AT1-AA(+) hypertensive patients on account of suppressing the AT1-AA's stimulation effect on EMPs generation.

Annual FEV1 changes and numbers of circulating endothelial microparticles in patients with COPD: a prospective study

ObjectiveGrowing evidence suggests that endothelial injury is involved in the pathophysiology of chronic obstructive pulmonary disease (COPD). Circulating endothelial microparticles (EMPs) increase in patients with COPD because of the presence...

The Effects of Smoking on Levels of Endothelial Progenitor Cells and Microparticles in the Blood of Healthy Volunteers

BackgroundCigarette smoking, both active and passive, is one of the leading causes of morbidity and mortality in cardiovascular disease. To assess the impact of brief smoking on the vasculature, we determined levels of circulating endothelial progenitor cells (EPCs) and circulating microparticles (MPs) following the smoking of one cigarette by young, healthy intermittent smokers.Materials and Methods12 healthy volunteers were randomized to either smoking or not smoking in a crossover fashion. Blood sampling was performed at baseline, 1, 4 and 24 hours following smoking/not smoking. The numbers of EPCs and MPs were determined by flow cytometry. MPs were measured from platelets, leukocytes and endothelial cells. Moreover, MPs were also labelled with anti-HMGB1 and SYTO 13 to assess the content of nuclear molecules.ResultsActive smoking of one cigarette caused an immediate and significant increase in the numbers of circulating EPCs and MPs of platelet-, endothelial- and leukocyte origin. Levels of MPs containing nuclear molecules were increased, of which the majority were positive for CD41 and CD45 (platelet- and leukocyte origin). CD144 (VE-cadherin) or HMGB1 release did not significantly change during active smoking.ConclusionBrief active smoking of one cigarette generated an acute release of EPC and MPs, of which the latter contained nuclear matter. Together, these results demonstrate acute effects of cigarette smoke on endothelial, platelet and leukocyte function as well as injury to the vascular wall.

Circulating microparticles in carriers of prothrombin G20210A mutation.

Factor V Leiden (FVL) and prothrombin gene mutation G20210A (PTM) are the two most common genetic polymorphisms known to predispose carriers to venous thromboembolism (VTE). A recent study in FVL carriers showed that circulating levels of microparticles (MP) may contribute to their thrombogenic profile. To further elucidate the prothrombotic state linked to genetic thrombophilia, we extended this study to carriers of PTM. The plasma level of annexin V-MP, endothelial-MP (EMP), platelet-MP (PMP), tissue factor-bearing MP (TF+) and the MP procoagulant activity (PPL) was measured in 124 carriers of PTM (105 heterozygous and 19 homozygous) and in 120 age- and gender-matched healthy individuals. Heterozygous and homozygous carriers of PTM showed significantly increased levels of annexin V-MP (2930 [1440-4646] MP/µl and 3064 [2412-4906] MP/µl, respectively) and significantly shorter PPL clotting time (54 [46-67] sec and 55 [46-64] sec) compared to controls (1728 [782-2122] MP/µl and 71 [61-75] sec, respectively; p<0.01). Similarly, heterozygous and homozygous subjects presented with significantly higher levels of EMP, PMP and TF+ than controls (p<0.05). PTM carriers with a VTE history had significantly higher MP numbers and activity than controls. No significant difference was seen between carriers with and without a VTE history. We conclude that the higher levels of circulating MP found in PTM carriers may play a role in the development of VTE possibly by increasing thrombin generation. Further studies are needed to better define the role of MP as triggering factors for the thrombotic complications characterizing mild genetic thrombophilic defects.

Correlation between brachial artery flow-mediated dilation and endothelial microparticle levels for identifying endothelial dysfunction in children with Kawasaki disease

We investigated vascular endothelial dysfunction by sonographic features of flow-mediated dilation (FMD) and circulating endothelial microparticles (EMPs) in Kawasaki disease (KD). Twenty-eight patients with KD were prospectively grouped according to stage of disease: acute, subacute, and convalescent. In addition, 28 healthy children and 28 febrile children were selected as controls. And cases in the convalescent phase were divided into two subgroups: coronary artery lesion (CAL) and no coronary lesion (NCAL). CD144(+)/CD42b(-), CD62E(+), and CD105(+) EMPs were measured by flow cytometry; FMD was obtained by sonography. There were significant differences in FMD among the five groups. When compared with healthy controls, there were significantly greater numbers of CD144(+)/CD42b(-), CD62E(+), and CD105(+) EMPs and a higher proportion of CD62E(+) EMPs in KD patients. The proportions and numbers of CD144(+)/CD42b(-), CD62E(+), and CD105(+) EMPs in KD patients were not statistically different than in febrile controls. There were no significant differences in FMD and EMPs between the CAL and NCAL subgroups. There were significantly negative correlations between the values of FMD and EMPs in the three phases of KD. The increased levels of EMPs have significant correlation with decreased values of FMD, both of which may reflect endothelial dysfunction in child KD.

Dietary flavanol intervention lowers the levels of endothelial microparticles in coronary artery disease patients

Current evidence suggests that regenerative v. degenerative endothelial responses can be integrated in a clinical endothelial phenotype, reflecting the net result between damage from risk factors and endogenous repair capacity. We have previously shown that a cocoa flavanol (CF) intervention can improve endothelial function and increase the regenerative capacity of the endothelium by mobilising circulating angiogenic cells in patients with coronary artery disease (CAD). The aim of the present study was to investigate whether CF can lower the levels of circulating endothelial microparticles (EMP), markers of endothelial integrity, along with improvements in endothelial function. The levels of EMP in the frozen plasma samples of CAD patients were measured along with endothelial function (flow-mediated vasodilation, FMD); n 16, FMD data published previously), and these data were compared with those of young (n 12) and age-matched (n 12) healthy control subjects. The CAD patients exhibited significantly increased levels of EMP along with impaired FMD when compared with the healthy control subjects. The levels of CD144⁺ and CD31⁺/41⁻ EMP were inversely correlated with FMD (r -0.67, P=0.01 and r -0.59, P=0.01, respectively). In these CAD patients, the levels of EMP were measured after they had consumed a drink containing 375 mg of CF (high-CF intervention, HiFI) or 9 mg of CF (macro- and micronutrient-matched low-CF control, LoFl) twice daily over a 30-d period in a randomised, double-blind, cross-over study. After 1 month of HiFI, the levels of CD31⁺/41⁻ and CD144⁺ EMP decreased (-25 and -23%, respectively), but not after LoFl. Our data show that flavanols lower the levels of EMP along with higher endothelial function, lending evidence to the novel concept that flavanols may improve endothelial integrity.

CD144+ endothelial microparticles as a marker of endothelial injury in neonatal ABO blood group incompatibility.

ABO antigens are expressed on the surfaces of red blood cells and the vascular endothelium. We studied circulating endothelial microparticles (EMP) in ABO haemolytic disease of the newborn (ABO HDN) as a marker of endothelial activation to test a hypothesis of possible endothelial injury in neonates with ABO HDN, and its relation with the occurrence and severity of haemolysis. Forty-five neonates with ABO HDN were compared with 20 neonates with Rhesus incompatibility (Rh HDN; haemolytic controls) and 20 healthy neonates with matched mother and infant blood groups (healthy controls). Laboratory investigations were done for markers of haemolysis and von Willebrand factor antigen (vWF Ag). EMP (CD144(+)) levels were measured before and after therapy (exchange transfusion and/or phototherapy). vWF Ag and pre-therapy EMP levels were higher in infants with ABO HDN or Rh HDN than in healthy controls, and were significantly higher in babies with ABO HDN than in those with Rh HDN (p<0.05). In ABO HDN, pre-therapy EMP levels were higher in patients with severe hyperbilirubinaemia than in those with mild and moderate disease or those with Rh HDN (p<0.001). Post-therapy EMP levels were lower than pre-therapy levels in both the ABO HDN and Rh HDN groups; however, the decline in EMP levels was particularly evident after exchange transfusion in ABO neonates with severe hyperbilirubinaemia (p<0.001). Multiple regression analysis revealed that the concentrations of haemoglobin, lactate dehydrogenase and indirect bilirubin were independently correlated with pre-therapy EMP levels in ABO HDN. Elevated EMP levels in ABO HDN may reflect an IgG-mediated endothelial injury parallel to the IgG-mediated erythrocyte destruction and could serve as a surrogate marker of vascular dysfunction and disease severity in neonates with this condition.

Quantification of Endothelial Microparticles on Modified Cytometric Bead Assay and Prognosis in Chest Pain Patients

Endothelial microparticles (EMPs) are vehicles released from activated or apoptotic endothelium. The aim of this study was to establish a new cytometric bead assay for EMPs and investigate the prognostic value of EMPs in chest pain patients. We invented and verified the cytometric bead assay to quantify EMP level in vitro. A total of 80 healthy volunteers and 350 chest pain patients were recruited and the EMPs measured. The major adverse cardiovascular events (MACE) of documented coronary artery disease patients were recorded in the follow-up period. The level of EMPs statistically correlated with those of endothelin-1 (ET-1) and intercellular adhesion molecule-1 (ICAM-1) in vitro. The EMP level in healthy subjects was <300.10. The patients had a remarkably higher EMP level than healthy subjects. Diabetes mellitus, EMP, and ET-1 levels were significantly associated with future cardiovascular events in chest pain patients. There was a significantly higher event incidence in the top tertile EMP level than in the lower tertile in the acute coronary syndrome (ACS) patient group. A novel EMP quantification assay has been successfully established. The EMPs in vitro and in patients were significantly correlated with ET-1 and ICAM-1 level. The patients with a higher EMP level had a higher risk of MACE. EMP level is a predictor for MACE in ACS patients.

Complement Activation Associated with ADAMTS13 Deficiency in Human and Murine Thrombotic Microangiopathy

This study addressed the contribution of ADAMTS13 deficiency to complement activation in thrombotic thrombocytopenic purpura (TTP). Renal tissue and blood samples were available from 12 TTP patients. C3 and C5b-9 deposition were demonstrated in the renal cortex of two TTP patients, by immunofluorescence and immunohistochemistry, respectively. C3 was also demonstrated in the glomeruli of Shiga toxin-2-treated Adamts13(-/-) mice (n = 6 of 7), but less in mice that were not Shiga toxin-2 treated (n = 1 of 8, p < 0.05) or wild-type mice (n = 0 of 7). TTP patient plasma (n = 9) contained significantly higher levels of complement-coated endothelial microparticles than control plasma (n = 13), as detected by flow cytometry. Exposure of histamine-stimulated primary glomerular endothelial cells to platelet-rich plasma from patients, or patient platelet-poor plasma combined with normal platelets, in a perfusion system, under shear, induced C3 deposition on von Willebrand factor-platelet strings (on both von Willebrand factor and platelets) and on endothelial cells. Complement activation occurred via the alternative pathway. No C3 was detected when cells were exposed to TTP plasma that was preincubated with EDTA or heat-inactivated, or to control plasma. In the perfusion system, patient plasma induced more release of C3- and C9-coated endothelial microparticles compared with control plasma. The results indicate that the microvascular process induced by ADAMTS13 deficiency triggers complement activation on platelets and the endothelium, which may contribute to formation of thrombotic microangiopathy.

Increased Circulating Endothelial Apoptotic Microparticle to Endothelial Progenitor Cell Ratio Is Associated with Subsequent Decline in Glomerular Filtration Rate in Hypertensive Patients

BackgroundRecent research indicates hypertensive patients with microalbuminuria have decreased endothelial progenitor cells (EPCs) and increased levels of endothelial apoptotic microparticles (EMP). However, whether these changes are related to a subsequent decline in glomerular filtration rate (GFR) remains unclear.Methods and ResultsWe enrolled totally 100 hypertensive out-patients with eGFR ≥30 mL/min/1.73 m2. The mean annual rate of GFR decline (△GFR/y) was −1.49±3.26 mL/min/1.73 m2 per year during the follow-up period (34±6 months). Flow cytometry was used to assess circulating EPC (CD34+/KDR+) and EMP levels (CD31+/annexin V+) in peripheral blood. The △GFR/y was correlated with the EMP to EPC ratio (r = −0.465, p<0.001), microalbuminuria (r = −0.329, p = 0.001), and the Framingham risk score (r = −0.245, p = 0.013). When we divided the patients into 4 groups according to the EMP to EPC ratio, there was an association between the EMP to EPC ratio and the ΔGFR/y (mean ΔGFR/y: 0.08±3.04 vs. −0.50±2.84 vs. −1.25±2.49 vs. −4.42±2.82, p<0.001). Multivariate analysis indicated that increased EMP to EPC ratio is an independent predictor of ΔeGFR/y.ConclusionsAn increased circulating EMP to EPC ratio is associated with subsequent decline in GFR in hypertensive patients, which suggests endothelial damage with reduced vascular repair capacity may contribute to further deterioration of renal function in patients with hypertension.

Unexplained pregnancy loss: a marker of basal endothelial dysfunction?

To compare the microparticle levels of women referred for unexplained pregnancy loss with those of parous controls. Incident case-control study. University medical center. 124 women consecutively referred for unexplained pregnancy losses (two or more losses at or before 21 weeks of gestational age, or at least one later loss), and 273 parous women without pregnancy loss. Numeration of circulating microparticles by flow cytometry after differentiation of subpopulations according to the expression of membrane-specific antigens (CD51, CD144, or CD146 for endothelial, CD41 for platelet, CD45 and CD66b for leukocyte and neutrophil microparticles). Plasma levels of microparticles. A relative hypercoagulable state assessed by thrombin generation test had been previously reported in such cases, so we hypothesized that this could be explained by an excess of procoagulant microparticles. The study women displayed statistically significantly lower platelet and higher endothelial microparticle levels than the controls. The parameters of the thrombin generation test were only correlated with the level of endothelial microparticles, with a low coefficient of Speerman's correlation (r=0.15). The difference in microparticle levels between the patients and controls does not clearly explain the hypercoagulable state reported in the patients but could reflect chronic endothelium damage.