Plasma ghrelin and pro-inflammatory markers in patients with obstructive sleep apnea and stable coronary heart disease

BACKGROUND Inflammation is associated with obstructive sleep apnea (OSA) and coronary heart disease (CHD). Ghrelin, a multifunctional hormone, may play a key role in patients with OSA and/or CHD. The aim of this study was to investigate plasma ghrelin and pro-inflammatory cytokines in patients with OSA and /or CHD and assess the association of these cytokines with ghrelin. MATERIAL AND METHODS Plasma ghrelin, interleukin-6(IL-6) and tumor necrosis factor alpha (TNF-á) were measured in 75 patients and in 25 age-, sex-, and BMI-matched healthy control subjects. These patients were further classified into 3 groups (25 with OSA, 25 with OSA and CHD, and 25 with CHD), matched for age, sex, body mass index, and the severity of OSA or CHD. RESULTS Plasma ghrelin levels were increased, and TNF-á and IL-6 were decreased in OSA patients with and without CHD, when compared with controls with similar CHD clinical characteristics (both P<0.05). Further, OSA patients with CHD tended to have higher plasma levels of TNF-á and IL-6, and lower plasma levels of ghrelin than OSA controls (P>0.05). Notably, plasma ghrelin levels were independently negatively correlated with plasma TNF-á and IL-6 (P<0.05). CONCLUSIONS Increased plasma ghrelin levels might constitute an independent determinant of decreased TNF-á and IL-6, suggesting that higher ghrelin level may in part represent a compensatory mechanism to overcome the pro-inflammatory effects of OSA. Further large-scale and prospective studies are needed to confirm these effects.