Interleukin-6 and Tumor Necrosis Factor-α in Patients with Obstructive Sleep Apnea-Hypopnea Syndrome

Background: In previous studies, significantly elevated levels of vascular endothelial growth factor (VEGF) have been reported in patients with severe obstructive sleep apnea-hypopnea syndrome (OSAHS). On the other hand, plasma tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) have been significantly higher in mild sleep apneics than in normal controls. However, this study included a small number of patients and milder cases of OSAHS. Objectives and Methods: To assess the involvement of IL-6 and TNF-α in VEGF increases in patients with severe OSAHS, serum levels of IL-6 and TNF-α were determined in patients with severe OSAHS (n = 110) and compared to those of controls (n = 45) using an enzyme-linked immunosorbent assay. Results: No significant increase in IL-6 or TNF-α was detected in the present study cohort. However, the body mass index was significantly correlated with the severity of the apnea-hypopnea index. Conclusions: These data suggest that the elevation in VEGF is not directly related to IL-6 or TNF-α levels. However, the question of whether VEGF is the cause or the result of OSAHS remains to be determined. Further studies are needed to clarify the role of IL-6 and TNF-α in the pathogenesis of OSAHS, in which obesity should be entered as an independent factor.