Circulating Microparticles and Coronary Plaque Components Assessed by Virtual Histology Intravascular Ultrasound of the Target Lesion in Patients with Stable Angina

Imbalance between the circulating endothelium-derived apoptotic microparticles and the endothelial colony-forming units of progenitor cells in patients undergoing diagnostic coronary angiography

PURPOSE

The involvement of the circulating endothelium-derived microparticles (EMPs) and the endothelial progenitor cells (EPCs) has been shown in the pathogenesis of coronary artery disease (CAD). The current study aimed to explore whether the Friesinger index is associated with the levels of the apoptotic CD144+/CD31+/annexin V+ ​EMPs and the number of endothelial colony-forming units of progenitor cells in patients undergoing coronary angiography.

PATIENTS AND METHODS

Fifty-seven patients with a median age of 62 years (range: 48-84 years) were enrolled. Quantification of the apoptotic CD144⁺/CD31⁺/annexin V⁺ EMPs was performed by flow cytometry. The number of endothelial colony-forming units defined by CFU-Hill was assessed by cell culture.

RESULTS

There was a positive correlation between the Friesinger index and the circulating levels of the apoptotic CD144⁺/CD31⁺/annexin V⁺ EMPs (rho=0.817, p<0.001), whereas a negative correlation was found with the number of CFU-Hill (rho ​= ​- 0.649, p<0.001). Multivariable logistic analysis showed that the risk of having moderate/severe CAD was five times greater among male patients (OR:5.32; 95% CI: 1.19 - 16.33; p=0.038) and almost one and a half times higher among those with a higher level of apoptotic CD144⁺/CD31⁺/annexin V⁺ EMPs (OR:1.74; 95% CI: 1.23 - 2.28; p=0.001). Finally, the circulating levels of apoptotic EMPs labelled for CD144⁺/CD31⁺/annexin V⁺ presented a good discrimination of moderate/severe CAD, with an AUC of 0.85 (95% CI ​= ​0.74 - 0.96; p< 0.001).

CONCLUSIONS

Moderate or severe CAD is associated with increased levels of apoptotic EMPs and reduced EPC colony-forming capacity, increasing the occurrence of endothelial injuries.

Endothelial dysfunction and platelet hyperactivity in type 2 diabetes mellitus: molecular insights and therapeutic strategies

The incidence and prevalence of diabetes mellitus is rapidly increasing worldwide at an alarming rate. Type 2 diabetes mellitus (T2DM) is the most prevalent form of diabetes, accounting for approximately 90-95% of the total diabetes cases worldwide. Besides affecting the ability of body to use glucose, it is associated with micro-vascular and macro-vascular complications. Augmented atherosclerosis is documented to be the key factor leading to vascular complications in T2DM patients. The metabolic milieu of T2DM, including insulin resistance, hyperglycemia and release of excess free fatty acids, along with other metabolic abnormalities affects vascular wall by a series of events including endothelial dysfunction, platelet hyperactivity, oxidative stress and low-grade inflammation. Activation of these events further enhances vasoconstriction and promotes thrombus formation, ultimately resulting in the development of atherosclerosis. All these evidences are supported by the clinical trials reporting the importance of endothelial dysfunction and platelet hyperactivity in the pathogenesis of atherosclerotic vascular complications. In this review, an attempt has been made to comprehensively compile updated information available in context of endothelial and platelet dysfunction in T2DM.

Microparticles as new markers of cardiovascular risk in diabetes and beyond

The term microparticle (MP) identifies a heterogeneous population of vesicles playing a relevant role in the pathogenesis of vascular diseases, cancer and metabolic diseases such as diabetes mellitus. MPs are released by virtually all cell types by shedding during cell growth, proliferation, activation, apoptosis or senescence processes. MPs, in particular platelet- and endothelial-derived MPs (PMPs and EMPs), are increased in a wide range of thrombotic disorders, with an interesting relationship between their levels and disease pathophysiology, activity or progression. EMP plasma levels have been associated with several cardiovascular diseases and risk factors. PMPs are also shown to be involved in the progressive formation of atherosclerotic plaque and development of arterial thrombosis, especially in diabetic patients. Indeed, diabetes is characterised by an increased procoagulant state and by a hyperreactive platelet phenotype, with enhanced adhesion, aggregation, and activation. Elevated MP levels, such as TF+ MPs, have been shown to be one of the procoagulant determinants in patients with type 2 diabetes mellitus. Atherosclerotic plaque constitutes an opulent source of sequestered MPs, called “plaque” MPs. Otherwise, circulating MPs represent a TF reservoir, named “blood-borne” TF, challenging the dogma that TF is a constitutive protein expressed in minute amounts. “Blood-borne” TF is mainly harboured by PMPs, and it can be trapped within the developing thrombus. MP detection and enumeration by polychromatic flow cytometry (PFC) have opened interesting perspectives in clinical settings, particularly for the evaluation of MP numbers and phenotypes as independent marker of cardiovascular risk, disease and outcome in diabetic patients.

Cell-derived microvesicles in cardiovascular diseases and antiplatelet therapy monitoring - A lesson for future trials? Current evidence, recent progresses and perspectives of clinical application

Circulating cell-derived microvesicles (MV) represent a subject of increasing interest in recent years as potential effectors in thrombosis, inflammation and vascular injury. Although several studies demonstrated an association between MV plasma concentrations and clinical manifestations of atherosclerosis as well as a clear effect of cardiovascular pharmacotherapy on MV formation pattern, the application of this promising biomarkers in clinical cardiology has been hindered so far due to heterogeneity of the hitherto studies employing non-standardized methodologies. Recently great progresses have been done and international initiatives were started to unify the pre-analytical and analytical procedures, improve the comparison of measurements between the laboratories and increase detector sensitivity of flow cytometry - a golden standard for MV assessment. Likewise, the concept of a "therapeutic window" of P2Y12 inhibitor therapy was introduced, as the prognostic significance of bleeding consequences is equally important with that of ischemic events, particularly with the expanding use of more potent P2Y12 inhibitors. In this review we summarize currently available studies on circulating MV in terms of cardiovascular diagnosis, risk stratification and influence of antiplatelet agents on the MV release to postulate possible future role of MV as supplementary biomarker in monitoring of individual response to antiplatelet therapy. Methodological pitfalls faced in the previous studies and obstacles that need to be addressed before further trials and translation of MV-based assays into clinical practice were defined.

Circulating cell-derived microparticles as biomarkers in cardiovascular disease

Cardiovascular diseases (CVDs) are a common cause of death, and a search for biomarkers for risk stratification is warranted. Elevated levels of cell-derived microparticles (MPs) are found in patients with CVD and in groups with risk factors for CVD. Subpopulations of MPs are promising biomarkers for improving risk prediction, as well as monitoring treatment. However, the field has been hampered by technical difficulties, and the ongoing development of sensitive standardized techniques is crucial for implementing MP analyses in the clinic. Large prospective studies are required to establish which MPs are of prognostic value in different patient groups. In this review, we discuss methodological challenges and progress in the field, as well as MP populations that are of interest for further clinical evaluation.