Oxidative stress and systemic inflammation in patients with sleep apnea: Role of obesity

Oxidative stress and systemic inflammation resulting from repeated hypoxia/reoxygenation cycles in obstructive sleep apnea-hypopnea syndrome (OSAHS) play a role in atherogenesis. It is unclear, however, if this association is independent of obesity. The aims of the present study were to compare markers of oxidative stress and systemic inflammation between patients with and without OSAHS independent of obesity, and to examine their interrelations. In experiment 1, 20 OSAHS patients, age 42.1 +/- 10.0 years, body mass index 26.3 +/- 2.7 kg/m(2), and apnea-hypopnea index 28.8 +/- 10.8 events/h, were individually matched with 20 control subjects, age 41.5 +/- 11.1 years, body mass index 26.0 +/- 2.9, and apnea-hypopnea index 6.5 +/- 2.4 events/h. In experiment 2, 15 OSAHS patients with body mass index > 27 were individually matched with 15 OSAHS patients having the same age and similar apnea severity with body mass index < 27. In both experiments, blood was drawn at the end of the sleep study for determination of lipid peroxidation markers, thiobarbituric-acid-reactive substances (TBARS) and peroxides and the antioxidant enzyme paraoxonase-1, and the systemic inflammatory markers C-reactive protein (CRP), ceruloplasmin and haptoglobin. OSAHS patients had significantly higher concentrations of TBARS (P < 0.0002) and peroxides (P < 0.03) and lower paraoxonase-1 (P < 0.02) than controls. No differences were found for the inflammatory markers but only in OSAHS patients there were significant correlations between the lipid peroxidation and inflammatory markers. There were no differences in lipid peroxidation between obese and non-obese patients, but CRP was higher (P < 0.03) in the obese patients. We conclude that sleep apnea is primarily associated with increased oxidative stress. Possibly, OSAHS influences systemic inflammatory pathways indirectly through oxidative stress.