Circulating cell-derived microparticles in patients with minimally symptomatic obstructive sleep apnoea.

Moderate-severe obstructive sleep apnoea (OSA) has been associated with several pro-atherogenic mechanisms and increased cardiovascular risk, but it is not known if minimally symptomatic OSA has similar effects. Circulating cell-derived microparticles have been shown to have pro-inflammatory, pro-coagulant and endothelial function-impairing effects, as well as to predict subclinical atherosclerosis and cardiovascular risk. In 57 patients with minimally symptomatic OSA, and 15 closely matched control subjects without OSA, AnnexinV-positive, platelet-, leukocyte- and endothelial cell-derived microparticles were measured by flow cytometry. In patients with OSA, median (interquartile range) levels of AnnexinV-positive microparticles were significantly elevated compared with control subjects: 2,586 (1,566-3,964) microL(-1) versus 1,206 (474-2,501) microL(-1), respectively. Levels of platelet-derived and leukocyte-derived microparticles were also significantly higher in patients with OSA (2,267 (1,102-3,592) microL(-1) and 20 (14-31) microL(-1), respectively) compared with control subjects (925 (328-2,068) microL(-1) and 15 (5-23) microL(-1), respectively). Endothelial cell-derived microparticle levels were similar in patients with OSA compared with control subjects (13 (8-25) microL(-1) versus 11 (6-17) microL(-1)). In patients with minimally symptomatic obstructive sleep apnoea, levels of AnnexinV-positive, platelet- and leukocyte-derived microparticles are elevated when compared with closely matched control subjects without obstructive sleep apnoea. These findings suggest that these patients may be at increased cardiovascular risk, despite being minimally symptomatic.