The selective reduction of soluble and cellular immune response factors only in those OSAS patients who exhibited good compliance to CPAP therapy provides further evidence for an ongoing systemic immune process in OSAS.
Background. Obstructive Sleep Apnea Syndrome (OSAS) is associated with inflammation, but obesity may be a confounding factor. Thus, the aim of this study was to explore differences in serum levels of inflammation markers between obese individuals with or without OSAS. Methods. Healthy individuals (n = 61) from an outpatient obesity clinic were examined by polysomnography and blood analysis, for measurement of TNF-α, IL-6, CRP, and fibrinogen levels. According to Apnea-Hypopnea Index (AHI), participants were divided into two BMI-matched groups: controls (AHI < 15/h, n = 23) and OSAS patients (AHI ≥ 15/h, n = 38). Results. OSAS patients had significantly higher TNF-α levels (P < .001) while no other difference in the examined inflammation markers was recorded between groups. Overall, TNF-α levels were correlated with neck circumference (P < .001), AHI (P = .002), and Oxygen Desaturation Index (P = .002). Conclusions. Obese OSAS patients have elevated TNF-α levels compared to BMI-matched controls, suggesting a role of OSAS in promoting inflammation, possibly mediated by TNF-a.
Weight loss has been recognized as a feature of advanced emphysema and a factor of poor prognosis, but its mechanisms remain obscure. Studies have demonstrated high serum concentrations of TNF-a (cachexin) in chronic obstructive pulmonary disease (COPD) patients with emphysema. Pink puffers (PP) COPD patients have worse tissue oxygenation when compared with blue bloaters (BB) COPD patients. Consequently, PP patients would become cachectic, whereas BB patients with better tissue oxygenation would not. The aim of this study is to test the hypothesis that malnutrition in emphysema is a cytokine-mediated marker of chronic progressive tissue hypoxia. Thirty male COPD patients, without clinical or laboratory evidence of infection and severe air way obstruction (FEV1 < 1.5 l) were allocated: 16 as pink puffers (PP) and 14 as blue bloaters (BB). Lung function measurements included FEV1, FVC, RV, TLC, DLCO and arterial blood gases on room air. TNF-a serum levels were measured by immunoenzymic method (ELISA). Tissue oxygenation was assessed from oxygen delivery (DO2), PvO2 and oxygen extraction ratio (O2ER) obtained after right heart catheterization with Swan Ganz catheter. PP patients demonstrated lower DLCO and higher TLC, FRC and PaO2 from BB. We found that oxygen delivery was better in our BB than in PP patients (CI 2.9 +/- 0.2 vs 2.5 +/- 0.4 l/min/m2--P < 0.01, DO2 16.1 +/- 2.1 vs 13.1 +/- 0.2 ml/min/kg--P < 0.001) and the same was found for tissue oxygenation (PvO2 34.6 +/- 2.9 vs 31.2 +/- 3.8 mmHg--P < 0.01, O2ER 0.27 +/- 0.02 vs 0.34 +/- 0.06%--P < 0.001). The TNF-a values were higher in PP (31.3 +/- 26 pg/ml vs 15.2 +/- 9.9 pg/ml--P < 0.05) and their percent fat-free mass (%FFM) was 49.6 +/- 11.5 vs 42 +/- 8%--P < 0.001. We found that COPD patients with lower DO2 had increased TNF-a levels; but the correlations between TNF-a serum levels and PvO2 or O2ER were not statistically significant. TNF-a levels were elevated in PP patients with tissue hypoxia and may be a factor contributing to the weight loss of these patients.
Background: Obstructive sleep apnea syndrome (OSAS) is associated with impaired glucose metabolism and insulin resistance. Retinol-binding protein-4 (RBP-4) is an adipokine, hypothesized to induce insulin resistance. Objectives: The aim of the study was to explore the association between serum RBP-4 levels and OSAS severity in nondiabetic, adherent to therapy OSAS patients and to investigate the role of continuous positive airway pressure (CPAP) in the alteration of RBP-4 levels. Methods: OSAS patients (n = 62) without comorbidities or medication use were included. Fasting RBP-4, glucose and insulin levels, HbA1c, homeostatic model assessment of insulin resistance index and lipid profile were measured at baseline and after 6 months of CPAP use. Patients were divided into group A (with fasting glucose levels <110 mg/dl, n = 47), and group B (with impaired fasting glucose (IFG), i.e. fasting glucose levels ≧110 mg/dl, n = 15). Results: RBP-4 levels were not associated with apnea-related indices, anthropometric characteristics or markers of glycemic control, insulin resistance or lipid profile. In group A (but not in group B), a significant reduction was observed in RBP-4 (p = 0.046), HbA1c (p = 0.005), LDL cholesterol (p = 0.034), and high-sensitivity C-reactive protein (hs-CRP, p = 0.033) levels after 6 months of CPAP use. Conclusions: RBP-4 levels were not correlated with sleep, anthropometric characteristics, markers of glycemic control and insulin sensitivity. OSAS patients without IFG respond well to CPAP use as evidenced by the significant reduction in RBP-4, HbA1c and, additionally, hs-CRP and LDL- cholesterol levels. This treatment effect is not observed in patients with IFG.
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