High Levels of TSP1+/CD142+ Platelet-derived Microparticles Characterise Young Patients with High Cardiovascular Risk and Subclinical Atherosclerosis

Circulating microparticles (cMPs) play important roles in cellular crosstalk and are messengers of cell activation. We have previously reported that platelet-released microparticles (pMPs) stimulate thrombosis and that lipid-lowering treatment as per guidelines in patients with familial hypercholesterolaemia (FH) is not sufficiently effective in reducing pro-inflammatory cell activation and, consequently, CD45+/CD3+-lymphocyte-derived cMP shedding. FH patients, due to life-long vascular exposure to high LDL-cholesterol levels, are at high cardiovascular risk (HCVR) and develop premature coronary artery disease. Our objectives were to investigate a) whether patients with HCVR have cMPs with a prothrombotic phenotype, and b) whether patients with magnetic resonance imaging (MRI) evidence of lipid-rich atherosclerotic lesions have a specific cMP profile regarding prothrombotic protein cargos. cMPs were isolated from HCVR-patients and from age/gender/treatment-matched control patients. cMP phenotype was characterised by triple-labelling flow cytometry. HCVR--patients have higher numbers of pMPs derived from activated platelets as well as of tissue factor-rich microparticles (TF+-cMPs) than controls (P< 0.0001). TF+-cMPs showed procoagulant activity, which associate with atherosclerotic plaque burden, indicating that TF in the cMPs is functional. In HCVR-patients, overall TF+-cMPs (monocyte-derived [CD142+/CD14+] and platelet-derived [CD142+/TSP1+]) and activated pMPs directly correlate with MRI-detected lipid-rich atherosclerotic plaques while inversely correlate with MRI-detected calcified plaques. C-statistics analysis showed that prothrombotic cMPs add significant prognostic value to a risk factor model for the prediction of lipid-rich plaques. In conclusion, the activation status of blood cells in HCVR-patients differed markedly from controls as shown by higher circulating levels of prothrombotic and TF+-cMPs. Prothrombotic cMP numbers identify subclinical atherosclerotic plaque burden.