Introduction: The correlations between the levels of cytokines, apnea, and obesity are not well understood. The aim of this study was to investigate the relationship between sleep apnea, body mass index (BMI) and plasma levels of leptin, ghrelin, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α).
Materials and methods: Levels of leptin, ghrelin, IL-6, and TNF-α were compared in 20 obese (BMI > 30 kg/m²) and 6 non-obese patients (BMI < 27 kg/m²) with Obstructive Sleep Apnea Syndrome (OSAS), and in 13 obese and 11 non-obese control subjects without OSAS. All patients were investigated with Polysomnography (PSG) and ENT examination with flexible endoscopy and Müller's maneuver. Twelve patients were treated with continuous positive airway pressure (CPAP) and 14 with surgery. Fasting leptin, ghrelin and cytokine levels were measured at baseline, 2 days and 6 months after initiation of CPAP treatment, and 6 months after surgery.
Results: Leptin, ghrelin and cytokine levels did not change significantly from baseline after 2 days of CPAP. After 6 months of CPAP or surgery, leptin, IL-6, and TNF-α levels were decreased in all OSAS patients. No difference in ghrelin levels was observed.
Discussion: Elevated leptin levels are not determined by obesity alone, since they decreased with Apnea Hypopnea Index reduction. Higher pro-inflammatory cytokine basal levels observed in patients with OSAS were not correlated with BMI.