Background/Aims: Obstructive sleep apnea hypoxia syndrome (OSAHS) is an independent risk factor for coronary artery disease (CAD). Treatment of OSAHS improves clinical outcome in some CAD patients, but the relationship between OSAHS and CAD is complex. Microparticles (MPs) are shed by the plasma membrane by either physiologic or pathologic stimulation. In the current study, we investigated the role of MPs in the context of OSAHS. Methods and Results: 54 patients with both suspected coronary artery stenosis and OSAHS were recruited and underwent both coronary arteriography and polysomnography. Circulating MPs were isolated and analyzed by flow cytometry. CAD+OSAHS patients exhibited greater levels of total MPs (Annexin V+), erythrocyte-derived MPs (CD235(+) Annexin V+), platelet-derived MPs (CD41(+) Annexin V+), and leukocyte-derived MPs (CD45(+) Annexin V+) compared to CAD alone patients or control. CAD+OSAHS patients expressed the greatest level of endothelial-derived MPs of all cellular origin types (CD144(+) Annexin V (+)). Treatment of human aortic endothelial cells (HAECs) with MPs isolated from CAD+OSAHS patients markedly increased HAEC permeability (as detected by FITC-dextran), and significantly upregulated mRNA levels of ICAM-1, VCAM-1, and MCP-1. Conclusion: OSAHS+CAD patients harbor increased levels of MPs, particularly the endothelial cell- derived subtype. When administered to HAECs, OSAHS+CAD patients MPs increase endothelial cell permeability and dysfunction. (C) 2017 The Author(s) Published by S. Karger AG, Basel