Evaluation of circulating markers of hepatic apoptosis and inflammation in obese children with and without obstructive sleep apnea.

Objective: Hepatocyte apoptosis and macrophage activation contribute to the disease progression of nonalcoholic fatty liver disease (NAFLD). Obstructive sleep apnea (OSA) in obese children is associated with the severity of NAFLD. The aim of this study was to evaluate plasma levels of soluble Fas (sFas), soluble Fas ligand (sFasL), cytokeratin 18 (CK18) (markers of apoptosis), and soluble CD163 (sCD163) (marker of macrophage activation) in obese children with and without OSA.

Methods: Consecutive obese children who were evaluated for OSA were recruited. The diagnosis of OSA was made using overnight polysomnography (PSG). Fasting blood samples were used to determine plasma CK18, sFas, sFasL, and sCD163 levels using specific sandwich enzyme-linked immunosorbent assay (ELISA).

Results: Fifty-eight subjects were included in the analysis with a mean age of 8.9 ± 3.2 years and a mean body mass index (BMI) z-score of 2.4 ± 0.49. Circulating sFas and sFasL levels were significantly lower in subjects with mild and severe OSA compared with those without OSA (p < 0.005 for both). In addition, sCD163 levels increased with an increasing severity of OSA (no OSA = 1.6 ± 0.25 mg/L, mild OSA = 2.3 ± 0.45, and severe OSA = 3.0 ± 0.52; p < 0.001), and they correlated with the apnea-hypopnea index (AHI) [rho (95% confidence interval, CI) of 0.71 (0.41, 1.00), p-value <0.001]. In six patients with severe OSA from whom samples were taken before and after tonsillectomy, the sCD163 level decreased significantly after treatment, and there was a trend toward an increase in sFasL.

Conclusion: Markers of apoptosis and macrophage activation are altered in obese children with OSA, indicating increased apoptotic and inflammatory pressures.