Circulating CD45+/CD3+ lymphocyte-derived microparticles map lipid-rich atherosclerotic plaques in familial hypercholesterolaemia patients

Circulating microparticles (cMPs) seem to play important roles in vascular function. Beyond markers of activated cells, cMPs may have potential paracrine functions and influence atherosclerosis. Here, our objective was to characterise a) the abundance and phenotype of cMPs in stable statin-treated heterozygous familial hypercholesterolaemia (FH) patients exposed to life-long hypercholesterolaemia and b) the principal phenotype associated to lipid-rich atherosclerotic plaques in hFH-patients with significant atherosclerotic plaque burden. An age/gender/treatment-matched group of adult-onset non-FH hypercholesterolaemic patients (n=37/group) was comparatively analysed. cMPs were characterised by flow cytometry using annexin-V and cell surface-specific antibodies. Our study shows that LLT-FH patients had higher overall cMP-numbers (p<0.005) than LLT-non-FH patients. Endothelial cell-shed cMPs were also significantly higherin FH (p<0.0005). Within the leukocyte-derived cMP-subpopulations, FH-patients had significantly higher lymphocyte- and monocyte-derived cMP-numbers as well as cMPs carrying leukocyte-activation markers. Normalisation of cMPs by LDL levels did not affect cMP number or phenotype, indicating that the proinflammatory effect was derived from chronic vascular damage. Levels of AV+-total, CD45+-pan-leukocyte and CD45+/CD3+-lymphocyte-derived cMPs were significantly higher in FH-patients with subclinical lipid-rich atherosclerotic plaques than fibrous plaques. Levels of CD45+/CD3+-lymphocyte-MPs above 20,000/ml could differentiate between FH-patients with lipidic or non-lipidic plaques (area under the ROC curve of 0.803, 95%CI: 0.641-0.965, p=0.008). In summary, in this snapshot cross-sectional study cMP concentration and phenotype in FH differed markedly from non-FH hypercholesterolaemia. Patients with life-long high LDL exposure have higher endothelial activation and higher proinflammatory profile, even under current state-of-the-art LLT. cMPs carrying lymphocyte-epitopes appear as markers of lipid-rich atherosclerotic plaques in FH.

Detection of circulating microparticles by flow cytometry: influence of centrifugation, filtration of buffer, and freezing

The clinical importance of microparticles resulting from vesiculation of platelets and other blood cells is increasingly recognized, although no standardized method exists for their measurement. Only a few studies have examined the analytical and preanalytical steps and variables affecting microparticle detection. We focused our analysis on microparticle detection by flow cytometry. The goal of our study was to analyze the effects of different centrifugation protocols looking at different durations of high and low centrifugation speeds. We also analyzed the effect of filtration of buffer and long-term freezing on microparticle quantification, as well as the role of Annexin V in the detection of microparticles. Absolute and platelet-derived microparticles were 10- to 15-fold higher using initial lower centrifugation speeds at 1500 × g compared with protocols using centrifugation speeds at 5000 × g (P < 0.01). A clear separation between true events and background noise was only achieved using higher centrifugation speeds. Filtration of buffer with a 0.2 μm filter reduced a significant amount of background noise. Storing samples for microparticle detection at -80°C decreased microparticle levels at days 28, 42, and 56 (P < 0.05 for all comparisons with fresh samples). We believe that staining with Annexin V is necessary to distinguish true events from cell debris or precipitates. Buffers should be filtered and fresh samples should be analyzed, or storage periods will have to be standardized. Higher centrifugation speeds should be used to minimize contamination by smaller size platelets.

Epidemiology and pathogenesis of diffuse obstructive coronary artery disease: the role of arterial stiffness, shear stress, monocyte subsets and circulating microparticles

Despite falling age-adjusted mortality rates coronary artery disease (CAD) remains the leading cause of death worldwide. Advanced diffuse CAD is becoming an important entity of modern cardiology as more patients with historical revascularisation no longer have suitable anatomy for additional procedures. Advances in the treatment of diffuse obstructive CAD are hampered by a poor understanding of its development. Although the likelihood of developing clinically significant (obstructive) CAD is linked to traditional risk factors, the morphology of obstructive CAD among individuals is highly variable - some patients have diffuse stenotic disease, while others have a focal stenosis. This is challenging to explain in mechanistic terms as vascular endothelium is equally exposed to injury stimulants. Patients with diffuse disease are at high risk of adverse outcomes, particularly if unsuitable for revascularisation. We searched multiple electronic databases (MEDLINE, EMBASE and the Cochrane Database) and reviewed the epidemiology, pathogenesis and prognosis relating to advanced diffuse CAD with particular focus on the role of endothelial shear stress, large artery stiffness, monocyte subsets and circulating microparticles. Key messages Although traditional CAD risk factors correlate strongly with disease severity, significant individual variation in disease morphology exists. Advanced, diffuse CAD is difficult to treat effectively and can significantly impair quality of life and increases mortality. The pathophysiology associated with the progression of CAD is the result of complex maladaptive interaction between the endothelium, cells of the immune system and patterns of blood flow.

Circulating microparticles in patients after ischemic stroke: a systematic review and meta-analysis

Microparticles (MPs), a class of cell products with biological activities, have been found to participate in a series of vascular activities. The aim of this article is to investigate the changes in the concentrations of MPs after ischemic stroke by meta-analysis. According to pre-established criteria, a strict screening of articles was performed through the Medline and Embase databases. Subsequently, the included studies were subjected to quality assessment and data extraction. Finally, a meta-analysis was performed on seven major outcomes from 985 noncerebrovascular disease controls and 988 ischemic stroke patients. The pooled concentrations of total MPs (TMPs), endotheliocyte-derived MPs (EMPs), platelet-derived MPs (PMPs), erythrocyte-derived MPs (RMPs), leukocyte-derived MPs (LMPs), and monocyte-derived MPs (MMPs) were significantly increased in the ischemic stroke patients compared to the noncerebrovascular disease controls, with the results as follows: TMPs [standardized mean difference (SMD), 1.12; 95% confidence interval (CI), 0.26-1.97; p=0.01], EMPs (SMD, 0.90; 95% CI, 0.67-1.13; p<0.00001), PMPs (SMD, 1.15; 95% CI, 0.69-1.60; p<0.00001), RMPs (SMD, 1.14; 95% CI, 0.57-1.71; p<0.0001), LMPs (SMD, 1.42; 95% CI, 0.74-2.10; p<0.0001), and MMPs (SMD, 1.09; 95% CI, 0.59-1.60; p<0.0001). However, the pooled concentration of lymphocyte-derived MPs (LyMPs) demonstrated no significant difference between the patients and the controls (SMD, 0.22; 95% CI, -0.19 to 0.63; p=0.29). The available data indicated that the circulating MPs, except for LyMPs, play an important role in the development and prognosis of ischemic stroke.

Circulating microparticle subpopulation in metabolic syndrome: relation to oxidative stress and coagulation markers

BACKGROUND

Circulating microparticles (MPs) contribute to the pathogenesis of atherothrombotic disorders and are raised in cardiovascular diseases. Herein, we aimed to investigate the effect of moderate metabolic abnormalities in an early stage of metabolic syndrome (MetS) on the level of MP subpopulations and to study relationships between MP subpopulations and both oxidative stress and coagulation markers.

METHODS

Flow cytometry used to evaluate circulating MPs subpopulations in 40 patients with an early stage MetS and 30 healthy controls. ELISA was used to quantify plasminogen activator inhibitor type 1/tissue plasminogen activator (PAI-1/TPA) while plasma glutathione peroxidase (GPx) activity was measured spectrophotometrically.

RESULTS

Total MPs were significantly elevated in MetS (P<0.001). Glutathione peroxidase and PAI1/TPA activity was significantly increased in subjects with MetS (P<0.001). Waist circumference, diastolic blood pressure, and total cholesterol positively influenced levels of total MPs, platelet-derived microparticles, and endothelium-derived microparticles. Fasting blood glucose, cholesterol, triglycerides, and low-density lipoprotein positively influenced the coagulation factors (TPA, PAI1). However, high-density lipoprotein negatively influenced platelet-derived MPs and factors associated with fibrinolysis (TPA, PAI1).

CONCLUSION

Elevated circulating MPs are associated with MetS abnormalities, oxidative stress and coagulation factors and may act as early predictor of metabolic syndrome with risk of cardiovascular disease.

Vascular damage effect of circulating microparticles in patients with ACS is aggravated by type 2 diabetes

As a common factor of both type 2 diabetes mellitus (T2DM) and acute coronary syndrome (ACS), circulating microparticles (MPs) may provide a link between these two diseases. The present study compared the content and function of MPs from patients with ACS with or without T2DM. MPs from healthy subjects (n=20), patients with ACS (n=24), patients with T2DM (n=20) and patients with combined ACS and T2DM (n=24) were obtained. After incubating rat thoracic tissue with MPs, the effect of MPs on endothelial‑dependent vasodilatation, expression of caveolin‑1 and endothelial nitric oxide synthase (eNOS), phosphorylation of eNOS at the S1177 and T495 sites and its association with heat shock protein 90 (Hsp90), and the generation of NO and superoxide anion (O_2˙‑) were determined. MP concentrations were higher in patients with T2DM and patients with ACS with or without T2DM than in healthy subjects. Moreover, MPs from patients with T2DM or ACS led to impairment in endothelial‑dependent vasodilatation, decreased expression of NO, as well as eNOS and its phosphorylation at Ser1177 and association with Hsp90, but increased eNOS phosphorylation at T495, caveolin‑1 expression and O_2˙‑ generation. These effects were strengthened by MPs from patients with ACS combined with T2DM. T2DM not only increased MP content but also resulted in greater vascular impairment effects in ACS. These results may provide novel insight into the treatment of patients with ACS and T2DM.

The signature of circulating microparticles in heart failure patients with metabolic syndrome

The role of pattern of circulating endothelial cell-derived microparticles, platelet-derived microparticles (PMPs), and monocyte-derived microparticles (MMPs) in metabolic syndrome (MetS) patients with chronic heart failure (CHF) is not still understood. The aim of the study was to investigate a pattern of circulating microparticles (MPs) in MetS patients with CHF in relation to neurohumoral and inflammatory activation. The study retrospectively involved 101 patients with MetS and 35 healthy volunteers. Biomarkers were measured at baseline of the study. The results of the study have shown that numerous circulating PMPs- and MMPs in subjects with MetS (with or without CHF) insufficiently distinguished from level obtained in healthy volunteers. We found elevated level of CD31+/annexin V+ MPs in association with lower level of CD62E+ MPs. Therefore, we found that biomarkers of biomechanical stress serum N-terminal brain natriuretic peptide and inflammation (high-sensitive C-reactive protein ,osteoprotegerin) remain statistically significant predictors for decreased CD62E+ to CD31+/annexin V+ ratio in MetS patients with CHF. In conclusion, decreased CD62E+ to CD31+/annexin V+ ratio reflected that impaired immune phenotype of MPs may be discussed as a surrogate marker of CHF development in MetS population.

New insights into the functions of intersectin-1s

Intersectin-1s (ITSN) is a ubiquitously expressed multifunctional protein known as a scaffold and regulator of the general endocytic machinery as well as a critical integrator of cellular signaling pathways. We showed recently that ITSN deficiency triggers a transforming growth factor β (TGFβ)/Alk5 signaling switch, from the canonical Smad 2/3 to the Erk1/2 MAPK pathway; moreover, endocytic impairment induced by ITSN deficiency enhances Alk5 ubiquitination and degradation and elicits TGFβ-paracrine effects mediated by circulating microparticles, leading to endothelial cell survival and increased proliferation. The studies expand our understanding of how ITSN facilitates cross-regulation of signaling pathways and provide insights into the involvement of ITSN deficiency in human disease.

Circulating microparticles enhanced rat vascular wall remodeling following endothelial denudation

This study tested the hypothesis that circulating microparticles (MPs) exacerbated vascular wall (VW) remodeling after endothelial denudation by 0.014 wire in a rat model. Adult male Sprague Dawley rats (n = 40) were equally categorized into group 1 [sham-control (SC); 3.0 mL saline intravenous injection], group 2 [SC + intravenous MPs (1.0 × 10⁷) derived from patients with carotid artery stenosis (CAS)], group 3 [femoral arterial endothelial denudation (FAED)], group 4 (FAED + MPs derived from healthy subjects), and group 5 (FAED + CAS-derived MPs). Animals were euthanized by day 28 after FAED procedure. The results demonstrated that neointimal area (NIA) (mm²), medial area, and number of infiltrated cells in medial layer were highest in group 5 and lowest in groups 1 and 2, and significantly higher in group 4 than those in group 3 (all P<0.0001), but no differences were noted between groups 1 and 2. However, the ratio of luminal area to VW area showed an opposite pattern compared to that of NIA among five groups (P<0.0001). Immunofluorescent study showed an identical pattern of changes in the numbers of inflammatory (F4/80, CD14, CD40, IL-β) and proliferative (Ki-67, Cx43) cells in VW compared to that of NIA among the five groups (all P<0.00). The mNRA expressions of inflammatory (MMP-9, NF-κB, TNF-α, IL-1β, iNOS, PDGF) and cell activation (c-Fos, c-Myc, osteopontin, PCNA) biomarkers showed an identical pattern compared to that of NIA among all groups (all P<0.001). Take altogether, CAS-derived MPs further aggravated MP-mediated VW remodeling after endothelial damage compared to that observed after administration of MPS derived from healthy subjects.

A multisite study to develop and validate first trimester, circulating microparticle biomarkers for tiered risk stratification of spontaneous preterm birth in nulliparas

BACKGROUND

Despite much research, advances in early prediction of spontaneous preterm birth (sPTB) has been slow. The evolving field of circulating microparticle (CMP) biology may identify novel blood-based, and clinically useful, biomarkers.

OBJECTIVE

To test the ability of a previously identified, 7-marker set of CMP-derived proteins from the first trimester of pregnancy, in the form of an in vitro diagnostic multivariate index assay (IVDMIA), to stratify pregnant patients according to their risk for sPTB.

STUDY DESIGN

We employed a previously validated set of CMP protein biomarkers, utilizing mass spectrometry assays and a nested case-control design in a subset of participants from the Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be (nuMoM2b). We evaluated these biomarkers in the form of an IVDMIA to predict risk for sPTB at different gestational ages. Plasma samples collected at 9- to 13-weeks' gestation were analyzed. The IVDMIA assigned subjects to 1 of 3 sPTB risk categories: low risk (LR), moderate risk (MR), or high risk (HR). Independent validation on a set-aside set confirmed the IVDMIA's performance in risk stratification.

RESULTS

Samples from 400 participants from the nuMoM2b cohort were used for the study; of these, 160 delivered<37 weeks and 240 delivered at term. Through Monte Carlo simulation in which the validation results were adjusted based on actual weekly sPTB incidence rates in the nuMoM2b cohort, the IVDMIA stratifications demonstrated statistically significant differences among the risk groups in time-to-event (birth) analysis (P<.0001). The incidence-rate adjusted cumulative risks of sPTB at ≤32 weeks' gestation were 0.4%, 1.6%, and 7.5%, respectively for the LR, MR, and HR groups, respectively. Compared to the LR group, the corresponding risk ratios of the IVDMIA assigned MR and HR group were 4.25 (95% confidence interval [CI] 2.2-7.9) and 19.92 (95% CI 10.4-37.4), respectively.

CONCLUSION

A first trimester CMP protein biomarker panel can be used to stratify risk for sPTB at different gestational ages. Such a multitiered stratification tool could be used to assess risk early in pregnancy to enable timely clinical management and interventions, and, ultimately, to enable the development of tailored care pathways for sPTB prevention.

Impact of Continuous Estroprogestin Treatment on Circulating Microparticle Levels in Deep Endometriosis Patients

There has been increasing interest in the study of new pathogenic mechanisms in endometriosis (END), including the coagulation/fibrinolysis system and its link with inflammation and tissue remodeling. It has been suggested that END patients, especially with deep-infiltrating (DE) forms, could present a hypercoagulable state revealing higher levels of proinflammatory and procoagulant markers, such as total circulating microparticles (cMPs) and cMP-TF (tissue factor), released by cells in response to damage, activation, or apoptosis. However, no previous study has assessed the effect of END hormonal treatments on cMP and cMP-TF levels. Therefore, the aim of this study was to evaluate the impact of these treatments on cMP and cMP-TF levels in DE patients. Three groups were compared: DE patients receiving a continuous combined oral contraceptive regimen (CCOCR) (n = 41), DE patients without CCOCR (n = 45), and a control group (n = 43). cMP and cMP-TF levels were evaluated in platelet-free plasma. A significant decrease in the total cMP levels was found in the DE group with CCOCR versus the group without CCOCR, reflecting a higher chronic inflammatory status in DE patients that decreased with the treatment. cMP-TF levels were higher in DE patients receiving CCOCR versus those not receiving CCOCR, suggesting that treatments containing estrogens play a predominant role in suppressing the inhibitory pathway of TF.