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/METHODS: Plasma ghrelin, interleukin-6(IL-6) and tumor necrosis factor alpha (TNF-α) 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-α 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-α 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-α and IL-6 (P<0.05). CONCLUSIONS: Increased plasma ghrelin levels might constitute an independent determinant of decreased TNF-α 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.