Lipid peroxides, superoxide dismutase and circulating IL-8 and GCP-2 in patients with severe obstructive sleep apnea: a pilot study

Abstract

Obstructive sleep apnea (OSA) is associated with cardiovascular morbidity and mortality and many other physiological and immunological disorders. An increase in hypoxia due to OSA may cause generation of reactive oxygen species (ROS). ROS are toxic to biomembranes and may lead to peroxidation of lipids. An increase in systemic biomarkers of inflammation and oxidative stress has been found in patients with OSA. The first aim of this study was to test the hypothesis that OSA is linked to increased oxidative stress (lipid peroxidation) and decreased antioxidant defense [superoxide dismutase (SOD)]. The second aim was to measure the serum levels of neutrophil chemokines [interleukin-8 (IL-8)], and granulocyte chemotactic protein-2 (GCP-2) in OSA patients. Twenty five patients with severe OSA and 17 healthy subjects were recruited. IL-8 and GCP-2 were measured in the serum by a specific enzyme immunoassay kit. Oxidative stress level was quantitated by measurement of thiobarbituric acid reactive substances. SOD enzymatic activity was measured by purely chemical system based on NAD(P)H oxidation. Mean SOD and lipid peroxidation concentrations of patients were not significantly different from those of control subjects (0.29+/-0.015 vs 0.31+/-0.01 U/ml and 4.64+/-0.57 vs 4.62+/-0.54 mmol/ml, respectively). Higher concentrations of IL-8 and GCP-2 were found in OSA patients (198.8+/-4.76 vs 180.83+/-3.38 and 383.34+/-46.19 vs 218+/-13.16 pg/ml, respectively, p<0.005). The present study does not support the hypothesis that OSA is linked to increased oxidative stress and decreased antioxidant defense. On the other hand, it suggests that systemic inflammation characterizes OSA patients.

Increased arterial stiffness in obstructive sleep apnea: a systematic review

“…72 Various studies have also found that C-reactive protein, tumor necrosis factor-a, interleukin-6 (IL-6), IL-8 and cell adhesion molecules such as intercellular adhesion molecule-1 are increased in the circulation in OSA patients independent of obesity. 10,15,73,74 Increased inflammation may have a role in the pathogenesis of OSA, increasing arterial stiffness and contributing to the early atherosclerosis found in OSA patients. 3 Furthermore, it also appears that endothelial dysfunction in OSA is partially mediated through apoptotic dysregulation; circulating apoptotic endothelial cells were found to be associated with AHI (r¼0.56, P¼0.004).…”

Sleep apnea: A proinflammatory disorder that coaggregates with obesity

“…29 Malondialdehyde levels also have been reported to be elevated in the intercostal muscles of individuals with sleep apnea, with elevations persisting even after long-term sleep apnea treatment. 30 Inconsistent associations with sleep apnea have been reported when oxidative stress was quantified by using measures of thiobarbituric acid reactive substances, [31][32][33] oxidized low-density lipoprotein, 33,34 and circulating free nitrotyrosine. 35 However, many of these measures are difficult to quantify accurately, and most studies have had small sample sizes.…”

Oxidative stress and oxidant signaling in obstructive sleep apnea and associated cardiovascular diseases

“…It should be noted that whether oxidative stress occurs in OSA patients is still controversial since some of more recent studies failed to demonstrate increased lipid peroxidation in OSA patients [32,33]. Svatikova et al [32] suggested that conflicting results may be explained by the presence of comorbidities and/or medications in OSA patients, the absence of control subjects matched closely for body mass index (BMI) and obesity, the presence of undiagnosed OSA in control populations, and the timing of oxidative stress measurements.…”