Effects of 10 days of modest intermittent hypoxia on circulating measures of inflammation in healthy humans

Obstructive sleep apnea (OSA) is a common disease which is associated with elevated inflammatory markers and adhesion molecules, possibly due to nightly intermittent hypoxia (IH). The purpose of this study was to test the hypothesis that IH would increase systemic inflammatory markers in healthy human males. Healthy, young male subjects (n = 9; 24 ± 2 years) were exposed to a single daily isocapnic hypoxia exposure (oxyhemoglobin saturation = 80%, 1 h/day) for 10 consecutive days. Serum granulocyte macrophage colony-stimulating factor, interferon-γ, interleukin-1β, interleukin-6, interleukin-8, leptin, monocyte chemotactic protein-1, vascular endothelial growth factor, intracellular adhesion molecule-1, and vascular cell adhesion molecule-1 were measured before and following the 10 days of IH using Luminex. Nine subjects completed the study (24 ± 2 years; 24 ± 2 kg/m2). The mean oxyhemoglobin saturation was 80.8 ± 1.6% during the hypoxia exposures. There was no significant change in any of the markers of inflammation (paired t test, P > 0.2 all cytokines). These findings suggest that (1) a more substantial or a different pattern of hypoxemia might be necessary to activate systemic inflammation, (2) the system may need to be primed before hypoxic exposure, or (3) increases in inflammatory markers in patients with OSA may be more related to other factors such as obesity or nocturnal arousal.