IL6 and obstructive sleep apnea syndrome: Several studies showed that, in OSA patients, the levels of circulating markers of inflammation, such as C-reactive protein (CRP), cytokines (interleukin 6 (IL-6), interleukin 8 (IL-8), tumor necrosis factor α (TNF-α)) and adhesion molecules are elevated, but the impact of CPAP therapy is still controversial [7,8].