Resistin and Oxidative Stress as Markers of Atherosclerosis in Obstructive Sleep Apnea

Introduction: Cardiovascular (CV) morbidity is increased in patients with obstructive sleep apnea (OSA). Oxidative stress and adipose tissue dysfunction are thought to be important factors for the accelerated atherosclerosis in OSA. The role of the various adipokines is however debated. Aim: The aim of the study was to check whether resitin may be a link between oxidative stress, adiposity and atherosclerosis in OSA patients. Methods: The common carotid artery (CCA) intima-media thickness (IMT), was measured by ultrasonography in 34 nondiabetic, non-hypertensive patients with untreated OSA. Oxidative stress (urinary 8-isoprostane levels) was measured by mass spectrometry (Cayman Chemical, USA). Insulin resistance was assessed by the homeostasis model assessment for insulin resistance (HOMA-IR). Resistin plasma levels were determined by an ELISA kit. Results: Urinary 8-isoprostanes, but not resistin were associated with the IMT after adjustment for CV risk factors, including HOMA-IR. Resistin levels increased with the degree of OSA severity, but did not correlate to markers of insulin resistance (HOMA-IR) or atherosclerosis. They were, however, associated with the time of sleep at SaO2<90% but not with the urinary 8-isoprostane levels. Conclusion: In non-diabetic, non-hypertensive OSA patients, resistin plasma levels do not correlate to markers of adiposity, insulin resistance or oxidative stress. IMT was associated only with the levels of oxidative stress (8-urinary isoprostanes).