Microparticles in stable and exacerbated COPD patients

Introduction: the influence of COPD on the endothelium and on the circulating microparticulum numbers is not completely understood. Microparticles (MP) are cell membrane-derived vesicles in the circulation originating from apoptotic or activated cells with 0,1-1,0µm size. Their outer membrane layer are rich in phosphatidylserine (PS) and phosphatidylethanolamine (PE). The origin of MPs is detectable, as these vesicles inherit the surface protein characteristics of their host cells (eg. white blood cells, platelets, red blood cells and endothelial cells). Objective: we aimed to compare MP numbers with different cellular origine in stable COPD patients and during exacerbation, associated with and without cardiovascular disease. Methods: we measured the MP numbers in 40 stable COPD patients, (20 with and 20 without cardiovascular disease) and in 20 patients with exacerbation compared to 20 healthy volunteers. MPs were defined as Annexin V-positive events in a size gate between 0,5-1,0 um and measured by Beckman-Coulter FC 500 flow cytomter. The cellular origine of MPs was detected by fluorochrome labelled antibodies: platelet (CD41, CD61, CD42a, PAC1), endothelial (CD31, CD62E) white blood cell (CD45,CD13) monocyte (CD14) and red blood cell (GlyA). Results: the total MP number in COPD patients were significantly higher then in healthy volunteers. CD42a+ (platelet origin), CD62E+ (endothelial origin) and CD14+ (monocyte origin) MP numbers were significantly higher in patients with exacerbated COPD than in the stable COPD patients. Conclusions: endothelial damage, mainly in pulmonary capillaries occurs during exacerbation. The role of platelet and monocyte origin MPs in COPD patients is not clear yet.