Study of endothelial dysfunction and vascular inflammation in sleep apnea, obesity and aged humans

ABSTRACT

Obstructive sleep apnea [OSA] has been associated with cardiovascular complications. The overnight repetitive hypoxia represents a form of oxidative stress in the vasculature which may activate the oxidant-sensitive, proinflammatory transcription factor nuclear factor kjB [NF-kjB], affecting endothelial function and atherosclerosis. We investigated whether the endothelial alterations attributed to OSA rather than to other confounding factors. Also, the production of inflammatory cytokine nuclear factor-kappa beta [NFKbeta] was investigated as the molecular mechanism involved in vascular endothelial dysfunction with OSA. Sixty subjects underwent attended nocturnal polysomnography were grouped by apnea hypopnea index control [AHI<5/h] and OSA cases [AHI>5/h] the cases were further classified according to age and BMI into subgroup IIA OSA, non-obese, middle age [35-52 y], subgroup IIB OSA, non-obese, older age group [55-68 y], subgroup IIIA OSA, obese, middle age group [35-52 y] and subgroup IIIB OSA, obese, older age group [55-68 y]. A morning venous blood sample was obtained. Neutrophils were isolated, and NF-kjB activity was determined. Plasma sVCAM-1 was assayed by enzyme-linked immunosorbent assay and flow-mediated dilation [FMD] was performed. NF-jB activation and plasma level of sVCAM-1 were significantly increased in OSA patients as compared to the control group and there was no significant difference between the obese and non-obese cases also no significant difference between the middle and old age cases. The degree of NF-kjB activation was positively correlated with indices of apnea severity[r = 0.938; p< 0.001]. FMD was significantly decreased in OSA patients as compared to the control group. These findings suggested that OSA is an independent risk factor for cardiovascular morbidity also that OSA leads to NF-kjB activation, which may constitute an important pathway linking OSA with systemic inflammation and cardiovascular disease