Levels Of Microparticles Research Articles

Changes in circulating microparticles in mice with ventilator-induced lung injury

To investigate the changes in serum level of microparticles (EMPs) in mice with ventilator-induced lung injury (VILI), and explore its significance in VILI. Forty-eight grade SPF male C57BL/6J mice were randomly divided into two groups, with 24 mice in each group: the mice in mechanical ventilation (MV) group were given high tidal volume (VT 30 mL/kg) MV for 4 hours after tracheal intubation, and those in spontaneous breathing group were spontaneously breathed for 4 hours. The apical blood of 12 mice in each group were collected, and serum levels of interleukins (IL-1β, IL-6) and tumor necrosis factor-α (TNF-α) were determined by enzyme linked immunosorbent assay (ELISA), and serum EMPs levels were determined by flow cytometer. The correlations between EMPs and IL-1β, IL-6, and TNF-α were analyzed by linear regression analysis. The lung tissues of other 12 mice in each group were harvested, and wet/dry weight (W/D) ratio was assessed. After hematoxylin-eosin (HE) staining, the morphological changes in lung tissue were observed under light microscope. After double staining of uranium acetate and lead citrate, the ultrastructural changes in lung tissue were observed with electron microscope. Compared with spontaneous breathing group, the levels of lung W/D ratio in MV group was significantly increased (5.47±0.14 vs. 4.34±0.11), the levels of IL-1β, IL-6, TNF-α and EMPs were also significantly increased [IL-1β (ng/L): 42.4±4.4 vs. 7.7±3.6, IL-6 (ng/L): 1 239.5±66.3 vs. 21.7±4.6, TNF-α (ng/L): 237.6±25.8 vs. 37.1±19.1, EMPs (cells/μL): 28.6±1.8 vs. 5.9±1.8, all P < 0.01]. It was shown by correlation analysis that EMPs were positively related with IL-1β, IL-6, and TNF-α (r value was 0.968, 0.932, 0.945, respectively, all P = 0.000). It was shown by fitting linear regression analysis that when EMPs increased by 1 cell/μL, IL-1β increased by 2.4 ng/L [95% confidence interval (95%CI) = 1.9-2.8, P < 0.001], IL-6 increased by 34.5 ng/L (95%CI = 25.1-44.0, P < 0.001), and TNF-α increased by 13.6 ng/L (95%CI = 10.3-16.9,P < 0.001). It was shown by light microscope that the structure of lung tissue and alveolar of mice in spontaneous breathing group appeared normal, while the shrinks of alveolar and disappearance of alveolar architecture were found in MV group. It was shown by electron microscopy that alveolar wall edema and thickening and broken alveolar septa were found in MV group, by contrast, the structure of alveolar was normal in spontaneous breathing group. 30 mL/kg VT ventilation for 4 hours could induce VILI with increase in EMPs, suggesting EMPs closely related to VILI, and EMPs level may be putative biomarker of VILI.

Plasma microparticles in Alzheimer's disease: The role of vascular dysfunction.

Cerebrovascular lesions, a potent stimulus for endothelial cell activation, trigger cognitive and degenerative changes and contribute to pathology of Alzheimer's disease (AD). Circulating microparticles (MPs) are actively involved in the pathogenesis of AD and cerebrovascular diseases, which share common vascular risk factors. We examined the plasma changes of endothelial MPs (EMPs) and platelet MPs (PMPs) in AD patients with vascular risk factors. The plasma Annexin V+ CD 41a- CD144+ EMPs and Annexin V+ CD41a+ CD144- PMPs of 37 patients with AD, with or without vascular risk factors (hypertension, diabetes, dyslipidemia, stroke, coronary artery disease, and smoking), and 10 age-matched controls were quantified by flow cytometry. Pearson correlation analysis used to evaluate the linear relationship between variables. Significantly higher plasma levels of EMPs were observed in AD patients with vascular risk factors as compared to the patients without vascular risk factors [Mean Difference (MD): 2587.80, 95% confidence interval (CI) 770.30-4404.80], and control subjects (MD: 4990.60, 95% CI, 3054.40-6926.79). Significant correlations were found between circulating EMPs, total MPs, and PMPs. There were no significant correlations between plasma levels of EMPs/ PMPs, and cognitive decline indices. Circulating EMP levels are influenced by AD disease status, and plasma levels of MPs and PMPs are associated with vascular risk factors in patients with AD. EMP phenotyping, as cellular biomarkers of vascular injury/dysfunction, and their effects on cerebral perfusion, and cognitive decline should be further investigated. Graphical abstract Vascular endothelial cell activation results in release of endothelial-derived microparticles (EMPs), which contributing to vascular dysfunction and cognitive decline.

Endothelial Microparticles are Associated to Pathogenesis of Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by obliteration of alveolar architecture, resulting in declining lung function and ultimately death. Pathogenic mechanisms remain unclear but involve a concomitant accumulation of scar tissue together with myofibroblasts activation. Microparticles (MPs) have been investigated in several human lung diseases as possible pathogenic elements, prognosis markers and therapeutic targets. We postulated that levels and cellular origins of circulating MPs might serve as biomarkers in IPF patients and/or as active players of fibrogenesis. Flow cytometry analysis showed a higher level of Annexin-V positive endothelial and platelet MPs in 41 IPF patients compared to 22 healthy volunteers. Moreover, in IPF patients with a low diffusing capacity of the lung for carbon monoxide (DLCO<40%), endothelial MPs (EMPs) were found significantly higher compared to those with DLCO>40% (p = 0.02). We then used EMPs isolated from endothelial progenitor cells (ECFCs) extracted from IPF patients or controls to modulate normal human lung fibroblast (NHLF) properties. We showed that EMPs did not modify proliferation, collagen deposition and myofibroblast transdifferentiation. However, EMPs from IPF patients stimulated migration capacity of NHLF. We hypothesized that this effect could result from EMPs fibrinolytic properties and found indeed higher plasminogen activation potential in total circulating MPs and ECFCs derived MPs issued from IPF patients compared to those isolated from healthy controls MPs. Our study showed that IPF is associated with an increased level of EMPs in the most severe patients, highlighting an active process of endothelial activation in the latter. Endothelial microparticles might contribute to the lung fibroblast invasion mediated, at least in part, by a fibrinolytic activity.

Acute effects of moderate altitude on biomarkers of cardiovascular inflammation and endothelial function and their differential modulation by dual endothelin receptor blockade.

Endothelial dysfunction is accompanied by the release of microparticles (MP). We sought to investigate the effect of moderate hypoxia on circulatory levels of microparticles, biomarkers of cardiovascular function and inflammation and on echocardiographic parameters in healthy volunteers staying at an altitude of 2978 m. Eighteen healthy volunteers were subjected to moderate hypoxia by staying at 2978 m above sea level for three days. Blood samples were evaluated for MP using flow cytometry. ELISA analysis was performed for sST2, H-FABP, suPAR and GDF-15. Moreover, the effect of dual endothelin-receptor blockade was investigated. Oxygen saturation decreased to 93%. A significant decrease of endothelial and platelet MP levels was found. These results were corroborated by a similar response in sST2 and suPAR plasma concentration. Endothelin-receptor blockade by macitentan only had a marginal influence on MP, sST2, H-FABP, suPAR and GDF-15 levels, though it led to a significant amelioration of echocardiographic parameters of right heart function. These experimental results show that moderate hypoxia due to altitude exposition led to a reduction in parameters of endothelial dysfunction as shown by a decrease in endothelial and platelet MP, sST2 and suPAR levels. A slight increase in pulmonary pressure at moderate altitude was decreased by dual endothelin receptor blockade.

Systemic Toxicity of Smokeless Tobacco Products in Mice.

Smokeless tobacco products such as snuff and snus are used worldwide. However, little is known about the systemic and cardiovascular toxicity of smokeless tobacco exposure. Biomarkers of endothelial activation and injury, immune functions, platelet activation and insulin resistance were measured in 8-week old male C57BL/6 mice exposed to commercial snuff, CRP-2 reference snuff, commercial snus, CRP-1 reference snus, and nicotine in drinking water (100 µg/mL) for 4, 12, and 24 weeks. Twenty-four weeks of exposure to smokeless tobacco products or nicotine significantly decreased the levels of circulating Flk+/Sca+ endothelial progenitor cells. Twelve and 24 weeks of exposure to all the smokeless tobacco products and nicotine significantly decreased the levels of circulating CD19+ B cells, CD4+ T cells, CD8+ T cells, and CD11b+ monocytes, whereas 4 weeks of exposure to Camel snus and Copenhagen snuff significantly depleted the levels of peripheral blood CD19+ B cells and CD11b+ monocytes. Twenty-four weeks of exposure to smokeless tobacco products or nicotine significantly decreased plasma IFNγ levels. However, plasma TNFα levels were significantly increased in mice exposed to Copenhagen snuff or nicotine for 24 weeks. This was accompanied by a five to sevenfold increase in the hepatic expression of TNFα. Neither smokeless products nor nicotine affected plasma lipoproteins, platelet activation, or systemic insulin sensitivity. Chronic exposure to snuff and snus suppresses circulating levels of EPCs, endothelial microparticles and immune cells, but increases plasma TNF-α levels. These effects of smokeless tobacco products are attributable, at least in part, to nicotine. Exposure to smokeless tobacco products results in the depletion of endothelial progenitor cells, which may impair the endothelium repair. Suppression of the circulating levels of immune cells upon exposure to smokeless tobacco products may increase the susceptibility to secondary infection. Increased formation of proinflammatory cytokines such as TNFα by nicotine or Copenhagen snuff may lead to vascular inflammation and thereby exacerbate atherogenesis.

Brain-Derived Microparticles in Patients with Severe Isolated TBI

ABSTRACTPrimary Objective: to investigate the presence of circulating microparticles (MPs) of brain tissue origin in the systemic and cerebrovenous blood of patients with severe traumatic brain injury (TBI).Research Design: Prospective observational study in 15 consecutive patients with severe isolated TBI.Methods and Procedures: We repeatedly measured concentrations of MPs expressing glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE) and aquaporin-4 (AQP4), in arterial and cerebrovenous blood at admittance to hospital and up to 72 hours after the injury.Main Outcomes and Results: Concentrations of MPs expressing GFAP and AQP4 were significantly higher in the TBI group compared with healthy controls: GFAP 2.0 [1.1–7.9] vs. 1.3 [1–2.1] × 106/mL, p < 0.001; AQP4 0.1 [0.07–0.22] vs. 0.08 [0.06–0.11] × 106/mL, p < 0.001 (median, range). No transcranial gradients were found. Levels of NSE-expressing MPs were also higher in the TBI group compared with healthy controls: 0.4 [0.25–2.1] vs. 0.26 [0.13–0.98] × 106/mL, p < 0.05; however, regarding NSE-positive non-platelet MPs, there were no differences between patients and controls.Conclusions: Patients with TBI have higher numbers of brain-derived MPs. Further studies are needed, however, to identify specific and sensitive MP markers of brain injury.

GW28-e0041 The Comparison of the level of Erythrocyte Microparticles between Acute Coronary Syndrome and Stable Angina Pectoris Patients

GW28-e0041 The Comparison of the level of Erythrocyte Microparticles between Acute Coronary Syndrome and Stable Angina Pectoris Patients

Circulating endothelial cells and microparticles for prediction of tumor progression and outcomes in advanced non-small cell lung cancer.

Circulating endothelial cells (CECs) and microparticles (MPs) are proposed as useful biosensors for angiogenesis and membrane damage in cancer. We investigated their predictive value for progression disease (PD) and clinical outcomes in advanced non-small cell lung cancer (NSCLC) patients treated with cytotoxic chemotherapy. Peripheral blood samples were obtained from 60 patients. Immunomagnetic separation (IMS) and flow cytometry techniques were used to quantify CECs and MPs, respectively. Receiver operating characteristics (ROC) analysis was used to determine the optimal cutoff values for CECs and MPs counts according to their levels in patients with an objective response (OR) and non-responders after treatment. Baseline serum biomarkers levels and their kinetics after chemotherapy were correlated with tumor response and outcomes in advanced NSCLC patients. Forty-seven patients presented an OR after chemotherapy. Of these, 28 patients progressed within three months. Through an increase in their levels during or after chemotherapy, CECs and MPs correctly predicted PD in 57% and 61% of these patients, respectively. Regarding tumor stage, NSCLC patients with stage IV had significantly higher pretreatment CECs and MPs levels than stage III patients (p= 0.037 and 0.018, respectively). Moreover, progression-free survival (PFS) was significantly longer in patients with high baseline CECs levels than those with low pretreatment CECs values (p= 0.05). Moreover, patients with high percentage change in CECs count after chemotherapy had significantly longer time to progression (TTP) duration (p= 0.018). Our findings suggest the increase in CECs and MPs number during or after chemotherapy as predictive biomarkers of tumor progression in advanced NSCLC patients. An association of basal CECs and MPs values with tumor stage was also shown in advanced NSCLC patients. However, baseline CECs levels and their kinetics after chemotherapy seem to be prognostic factors in advanced NSCLC.

Immune status of patients with haemophilia A before exposure to factor VIII: first results from the HEMFIL study.

Previous cross-sectional studies showed that some patients with haemophilia A (HA) without inhibitor presented a pro-inflammatory profile during factor VIII (FVIII) replacement therapy. Furthermore, an anti-inflammatory/regulatory state was described in HA patients after inhibitor development. However, no study investigated the levels of these biomarkers before exposure to exogenous FVIII. This study investigated the immunological profile of previously untreated patients (PUPs) with HA in comparison with non-haemophiliac boys. A panel of chemokines and cytokines was evaluated in the plasma of 40 PUPs with HA and 47 healthy controls. The presence of microparticles was assessed in the plasma of 32 PUPs with HA and 47 healthy controls. PUPs with HA presented higher levels of CXCL8 (IL8), IL6, IL4, IL10, IL2, IL17A (IL17), and lower levels of CXCL10 (IP-10) and CCL2 (MCP-1) than the age-matched healthy controls (P<0·05). We also observed higher levels of microparticles derived from endothelium, erythrocytes, platelets, leucocytes, neutrophils, and T lymphocytes in patients in comparison with controls (P<0·05). Compared with controls, PUPs with HA presented a distinct immunological profile, characterized by a prominent pro-inflammatory status that appears to be regulated by IL4 and IL10.

Metformin reduces total microparticles and microparticles-expressing tissue factor in women with polycystic ovary syndrome.

The objective of this study was to evaluate the levels of total microparticles (MPs) and microparticles-expressing tissue factor (TFMPs) in women with polycystic ovarian syndrome (PCOS) who use metformin comparing to those who do not take metformin. We quantified total MPs and TFMPs in the plasma of 50 patients with PCOS-13 of these women used metformin (850mg 2×/day during at least 6months) and the other 37 did not. For this purpose, the microparticles (MPs) were purified by differential centrifugation of the plasma and, subsequently, by flow cytometry, using annexin-V and CD142 as markers. Total MPs levels were lower in treated patients (59.58±28.43MPs/µL) when compared to untreated group (97.32±59.42; p=0.033). Plasma levels of TFMPs were also significantly lower in the group of patients who used metformin (1.10±0.94MPs/µL) when compared to untreated patients (2.20±1.42MPs/µL) (p=0.003). Considering that metformin reduced the levels of total MPs and TFMPs, our results suggest that this mechanism could be involved in the antithrombotic metformin effect, corroborating with the indication of this drug in the PCOS treatment.

Elevated plasma levels of procoagulant microparticles are a novel risk factor for thrombosis in patients with myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs), including polycythemia vera and essential thrombocythemia, are frequently associated with thrombotic complications. Prevention of thrombotic events is thus a primary aim of the current treatment for these disorders. Although it is known that microparticles (MPs), which are small vesicles released from cell membranes and circulate in the blood, directly contribute to thrombosis via their procoagulant activity, potential associations between plasma levels of MPs and the risk of thrombotic events in MPNs have not been reported. In the present study, we characterized plasma levels of MPs and assessed their potential association with the occurrence of thrombotic events in 59 patients with MPNs. Plasma levels of procoagulant MPs expressing tissue factor (TF+ MPs) were significantly higher in patients suffering thrombotic events than in patients without such events (median/μl plasma: 33.8 vs 47.2, p=0.02). Among patients who developed thrombotic events, irrespective of patients' blood counts, TF+ MP were significantly higher in patients without cytoreductive therapy than in those receiving cytoreductive therapy (101.2 vs. 42.5, p<0.001). These results suggest that elevated levels of TF+ MP may be considered as a novel surrogate marker for thrombotic events in MPN patients. Further studies are needed to clarify the mechanism involved.

Microparticles from stored red blood cells enhance procoagulant and proinflammatory activity.

The pathomechanisms of morbidity due to blood transfusions are not yet entirely understood. Elevated levels of red blood cell-derived microparticles (RMPs) are found in coagulation-related pathologies and also in stored blood. Previous research has shown that RMPs mediate transfusion-related complications by the intrinsic pathway. We hypothesized that RMPs might play a role in post-transfusion thrombotic complications by enhancing procoagulant activity also through the extrinsic pathway of coagulation. In this laboratory study, blood from 18 healthy volunteers was stimulated with microparticles from expired stored red blood cells. Various clotting parameters were recorded. Flow cytometry, enzyme-linked immunosorbent assays, and real-time polymerase chain reaction were used to investigate possible mediating mechanisms. The addition of RMPs shortened the clotting time from 194 to 161 seconds (p < 0.001). After incubation with RMPs, there was increased expression of tissue factor (TF) on monocytes and in plasma. TF messenger RNA expression increased in a time-dependent and concentration-dependent manner. There was a significant induction of interleukin-1β and interleukin-6. After stimulation with RMPs, there was a significant increase in the number of activated platelets, an increased percentage of PAC-1/CD62P (procaspase activating compound-1/platelet surface P-selectin) double-positive platelets, and an increased number of platelet-neutrophil duplets and platelet-monocyte duplets, indicating enhanced interaction of platelets with neutrophils and monocytes. Levels of CXCL-8 (C-X-C motif chemokine ligand 1) and interleukin-6 were significantly higher after treatment with RMPs. Our results suggest that RMPs trigger coagulation through TF signaling, induce the secretion of proinflammatory cytokines, and induce cell-cell interaction between platelets and neutrophils. Thus, under certain conditions, RMPs could play a role in post-transfusion complications through these mechanisms.

Platelet function and microparticle levels in atrial fibrillation: Changes during the acute episode

BackgroundThrombotic risk constitutes a major complication of atrial fibrillation (AF). Platelets and microparticles (MPs) are important for hemostasis and thrombosis, however their participation during AF is not well known. The aim of this study was to characterize platelet function and MPs procoagulant and fibrinolytic activity in AF patients and to determine the effects of an acute-AF episode. MethodsBlood was collected from paroxysmal (21) and persistent (16) AF patients referred for AF catheter ablation. Ten patients in sinus rhythm for 10days were induced in AF allowing comparisons of left atrium samples before and after induction. Platelet aggregation with ADP, TRAP, collagen, and ristocetin was studied. Platelet surface expression of PAR-1, αIIbβ3, GPIb and P-selectin were evaluated by flow cytometry, and MPs-associated procoagulant and fibrinolytic activity levels were determined by functional assays. ResultsA specific reduction in platelet aggregation to TRAP, activating the thrombin receptor PAR-1, was found in all AF patients. No differences in platelet receptor expression were found. Yet, after acute-induced AF, the platelet response was improved. Furthermore, a significant decrease of left atrium tissue factor-dependent procoagulant activity of MPs was observed. ConclusionAcute episodes of AF results in a decrease in MPs-associated tissue factor activity, possibly corresponding to consumption, which in turn favors coagulation and the local production of thrombin. A decreased platelet basal aggregation to TRAP may result from PAR1 desensitization, whereas the improved response after an induced episode of AF suggests activation of coagulation and PAR1 re-sensitization.

Mitochondrial DNA-enriched microparticles promote acute-on-chronic alcoholic neutrophilia and hepatotoxicity.

Over the last several years, one of the major advances in the field of alcoholic liver disease research was the discovery that binge alcohol consumption induced neutrophilia and hepatic neutrophil infiltration in chronically ethanol-fed mice and human subjects with excessive alcohol use (EAU); however, the underlying mechanisms remain obscure. Here, we demonstrated that chronic EAU patients with a history of recent excessive drinking (EAU + RD) had higher serum levels of mitochondrial DNA (mtDNA)-enriched microparticles (MPs) than EAU without recent drinking (EAU - RD) and healthy controls, which correlated positively with circulating neutrophils. Similarly, mice with chronic-plus-binge (E10d + 1B) ethanol feeding also had markedly elevated serum levels of mtDNA-enriched MPs, with activation of hepatic ER stress and inflammatory responses. Inhibition of ER stress by gene KO or inhibitors attenuated ethanol-induced elevation of mtDNA-enriched MPs, neutrophilia, and liver injury. The data from the study of hepatocyte-specific deletion of the protein kinase RNA-like ER kinase (Perk) gene in mice and of cultured hepatocytes demonstrated that hepatocytes were the main source of mtDNA-enriched MPs after ethanol feeding. Finally, administration of mtDNA-enriched MPs isolated from E10d+1B-fed mice caused neutrophilia in mice. In conclusion, E10d + 1B ethanol consumption activates hepatic ER stress-dependent mtDNA-enriched MP release, leading to neutrophilia and liver injury.

Flow rate calibration to determine cell-derived microparticles and homogeneity of blood components

BackgroundCell-derived microparticles (MPs) are currently of great interest to screening transfusion donors and blood components. However, the current approach to counting MPs is not affordable for routine laboratory use due to its high cost. AimThe current study aimed to investigate the potential use of flow-rate calibration for counting MPs in whole blood, packed red blood cells (PRBCs), and platelet concentrates (PCs). MethodsThe accuracy of flow-rate calibration was investigated by comparing the platelet counts of an automated counter and a flow-rate calibrator. The concentration of MPs and their origins in whole blood (n=100), PRBCs (n=100), and PCs (n=92) were determined using a FACSCalibur. The MPs’ fold-changes were calculated to assess the homogeneity of the blood components. ResultsComparing the platelet counts conducted by automated counting and flow-rate calibration showed an r2 of 0.6 (y=0.69x+97,620). The CVs of the within-run and between-run variations of flow-rate calibration were 8.2% and 12.1%, respectively. The Bland–Altman plot showed a mean bias of −31,142platelets/μl. MP enumeration revealed both the difference in MP levels and their origins in whole blood, PRBCs, and PCs. Screening the blood components demonstrated high heterogeneity of the MP levels in PCs when compared to whole blood and PRBCs. ConclusionsThe results of the present study suggest the accuracy and precision of flow-rate calibration for enumerating MPs. This flow-rate approach is affordable for assessing the homogeneity of MPs in blood components in routine laboratory practice.

Clinical significance of circulating microparticles in Ph- myeloproliferative neoplasms.

Microparticles (MPs) are small membrane vesicles that are classified into subcategories based on their origin, such as platelet-derived MPs (PMPs), endothelial MPs (EMPs), red blood cell MPs (RMPs) and tissue factor MPs (TF + MPs). Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-MPN) are disorders characterized by abnormal haematopoiesis, thrombosis and the JAK2V617F mutation. MPs are biomarkers for procoagulant state in cancer patients, but their relevance in patients with Ph-MPN was unclear. The present study aimed to measure MP variation in MPN patients and evaluate association with the JAK2V617F mutation and with thrombosis and splenomegaly. In total, 92 patients with MPN were enrolled in the present study, including 60 with essential thrombocythaemia (ET), 20 with polycythaemia vera (PV), and 12 with primary myelofibrosis (PMF). RMPs, PMPs, TF + MPs and EMPs were measured by flow cytometry. The levels of RMPs, PMPs, EMPs and TF + MPs in patients with Ph-MPN were all found to be significantly increased compared with controls (P<0.05). Additionally, the levels of all four types of MPs in the PMF group were significantly increased compared with the PV group (P<0.05), and the level of RMPs in the PMF group was significantly increased compared with the ET group (P<0.05). MP levels were increased in the Ph-MPN patients with thrombosis compared with patients without thrombosis (P<0.05). MP levels were increased in Ph-MPN patients with splenomegaly compared with patients without splenomegaly (P<0.05). The level of PMPs in patients with the JAK2V617F mutation was increased compared with patients without the mutation (P<0.05). In conclusion, the present study showed that MPs are associated with Ph-MPN pathogenesis, and may promote thrombosis.

Microparticles in acute coronary syndrome

BackgroundEmerging evidence supports the role of cell-derived microparticles (MPs) in the pathophysiology of acute coronary syndrome (ACS). ObjectivesTo explore the relationship between coronary and systemic MP levels, investigate the correlation between MPs, inflammatory markers and Troponin T in patients with ACS. MethodsThirty seven patients with ACS scheduled for percutaneous coronary interventions (PCI) were studied. Eleven patients with stable angina (SA) were included as a control group. AnnexinV+MPs (AnV+MPs) and activated platelet-monocyte aggregates (PMA) from right atrium (RA) and culprit coronary artery (CO) distal to culprit lesion were measured using flow cytometry. High sensitivity C-reactive protein (CRP), Interleukin - 6 (IL-6), tumour necrosis factor – α (TNF-α), serum amyloid A (SAA) and Troponin T were assayed. ResultsTotal and cell specific AnV+MP expression were higher in the ACS group in both the CO and RA, with greater levels detected in the CO. Platelet activation showed positive correlation with Troponin-T and platelet MP in both CO and RA of the ACS group (r=0.4 for both; p=0.04 & p=0.03 respectively). Inflammatory markers levels did not differ between the ACS and SA patients. ConclusionsElevated coronary and systemic MP levels and positive correlation of platelet activation with Troponin-T and platelet MPs suggest a pathogenic role for MPs in ACS.

Platelet-derived microparticles regulates thrombin generation via phophatidylserine in abdominal sepsis.

Sepsis is associated with dysfunctional coagulation. Recent data suggest that platelets play a role in sepsis by promoting neutrophil accumulation. Herein, we show that cecal ligation and puncture (CLP) triggered systemic inflammation, which is characterized by formation of IL-6 and CXC chemokines as well as neutrophil accumulation in the lung. Platelet depletion decreased neutrophil accumulation, IL-6, and CXC chemokines formation in septic lungs. Depletion of platelets increased peak thrombin formation and total thrombin generation (TG) in plasma from septic animals. CLP elevated circulating levels of platelet-derived microparticles (PMPs). In vitro generated PMPs were a potent inducer of TG. Interestingly, in vitro wild-type recombinant annexin V abolished PMP-induced thrombin formation whereas a mutant annexin V protein, which does not bind to phosphatidylserine (PS), had no effect. Administration of wild-type, but not mutant annexin V, significantly inhibited thrombin formation in septic animals. Moreover, CLP-induced formation of thrombin-antithrombin complexes were reduced in platelet-depleted mice and in animals pretreated with annexin V. PMP-induced TG attenuated in FXII- and FVII-deficient plasma. These findings suggest that sepsis-induced TG is dependent on platelets. Moreover, PMPs formed in sepsis are a potent inducer of TG via PS exposure, and activation of both the intrinsic and extrinsic pathway of coagulation. In conclusion, these observations suggest that PMPs and PS play an important role in dysfunctional coagulation in abdominal sepsis.

Circulating microparticle levels are reduced in patients with ARDS

BackgroundIt is unclear how to identify which patients at risk for acute respiratory distress syndrome (ARDS) will develop this condition during critical illness. Elevated microparticle (MP) concentrations in the airspace during ARDS are associated with activation of coagulation and in vitro studies have demonstrated that MPs contribute to acute lung injury, but the significance of MPs in the circulation during ARDS has not been well studied. The goal of the present study was to test the hypothesis that elevated levels of circulating MPs could prospectively identify critically ill patients who will develop ARDS and that elevated circulating MPs are associated with poor clinical outcomes.MethodsA total of 280 patients with platelet-poor plasma samples from the prospective Validating Acute Lung Injury biomarkers for Diagnosis (VALID) cohort study were selected for this analysis. Demographics and clinical data were obtained by chart review. MP concentrations in plasma were measured at study enrollment on intensive care unit (ICU) day 2 and on ICU day 4 by MP capture assay. Activation of coagulation was measured by plasma recalcification (clot) times.ResultsARDS developed in 90 of 280 patients (32%) in the study. Elevated plasma MP concentrations were associated with reduced risk of developing ARDS (odds ratio (OR) 0.70 per 10 μM increase in MP concentration, 95% CI 0.50–0.98, p = 0.042), but had no significant effect on hospital mortality. MP concentration was greatest in patients with sepsis, pneumonia, or aspiration as compared with those with trauma or receiving multiple blood transfusions. MP levels did not significantly change over time. The inverse association of MP levels with ARDS development was most striking in patients with sepsis. After controlling for age, presence of sepsis, and severity of illness, higher MP concentrations were independently associated with a reduced risk of developing ARDS (OR 0.69, 95% CI 0.49–0.98, p = 0.038). MP concentration was associated with reduced plasma recalcification time.ConclusionsElevated levels of circulating MPs are independently associated with a reduced risk of ARDS in critically ill patients. Whether this is due to MP effects on systemic coagulation warrants further investigation.

Differences of microparticle patterns between sickle cell anemia and hemoglobin SC patients.

Sickle cell anemia (SCA) and hemoglobin SC (HbSC) disease are the two most common forms of sickle cell disease (SCD), a frequent hemoglobinopathy which exhibits a highly variable clinical course. Although high levels of microparticles (MPs) have been consistently reported in SCA and evidence of their harmful impact on the SCA complication occurrences have been provided, no data on MP pattern in HbSC patients has been reported so far. In this study, we determined and compared the MP patterns of 84 HbSC and 96 SCA children, all at steady-state, using flow cytometry. Most of circulating MPs were derived from platelets (PLTs) and red blood cells (RBCs) in the two SCD syndromes. Moreover, we showed that HbSC patients exhibited lower blood concentration of total MPs compared to SCA patients, resulting mainly from a decrease of MP levels originated from RBCs and to a lesser extent from PLTs. We did not detect any association between blood MP concentrations and the occurrence of painful vaso-occlusive crises, acute chest syndrome and pulmonary hypertension in both patient groups. We also demonstrated for the first time, that whatever the considered genotype, RBC-derived MPs exhibited higher externalized phosphatidylserine level and were larger than PLT-derived MPs.