Among the distinctive features of Covid-19, numerous reports have stressed the importance of vascular damages associated with coagulopathy onset. Microparticles (MPs) shed by apoptotic/stimulated cells are reliable markers of vascular damage released upon pro-inflammatory conditions and behave as active participants in the early steps of clot formation. In addition, MPs carry ACE1 and ACE2, the cell-entry receptor for SARS-Cov2 in the vasculature and up-regulate ACE1 expression in neighbouring endothelial cells. This may contribute to unopposed angiotensin II accumulation which further exacerbate tissue injury and promote both inflammation and thrombosis. The aim of the study is to evaluate the impact of circulating MPs on ACE2 expression, the cell-entry receptor for SARS-Cov2 on endothelial cells.

Circulating MPs will be isolated from Covid-19 patients with lupus anticoagulant, from coronary artery diseases patients and from healthy volunteers without cardiovascular risk factors. Quantification of MPs will be realized by prothrombinase assay. Primary endothelial cells (ECs) from porcine coronary artery or porcine pulmonary artery will be isolated and cultured. ECs will be exposed to circulating MPs. Phenotypical changes (ACE2 expression, cytoadhesins, cytokines, tissue factor expression) of ECs will be examined. Susceptibility of ECs to SARS-COV-2 infection will be determined.

Inclusion Criteria:

• COVID-19 patients: age > 18 yr
• SARS-COV-2 infection within 12 months and positive lupus anticoagulant
• Patients with cardiovascular risk factors: at least among
• Hypertension, Dyslipidemia, Diabetes mellitus, obesity, smoker, Healthy volunteers

Exclusion Criteria:

• Significant comorbidities (active cancer, auto-immune diseases…)

• Covid-19 patients
• patients with coronary artery disease
• healthy volunteers