Abstract
CONTEXT: Asthma and obstructive sleep apnea (OSA) are prevalent respiratory disorders that frequently coexist. Continuous positive airway pressure (CPAP) therapy is the standard treatment for OSA. However, its effects on systemic inflammation and glucocorticoid responsiveness in OSA patients with asthma are largely unknown. AIMS: To examine the potential role of CPAP therapy in reducing systemic inflammation and improving glucocorticoid responsiveness in asthmatic patients with OSA. SETTINGS AND DESIGN: A case-control study was conducted at the respiratory and sleep clinics involving patients with OSA and patients with asthma and OSA. METHODS: The levels of inflammatory asthma biomarkers (interleukin [IL]-4, IL-17A, IL-8, IL-2, and interferon-γ [IFN-γ]), and glucocorticoid receptors (GR)-α and GR-β, were determined to compare systemic inflammation and glucocorticoid responsiveness between pre- and post-1-month CPAP treatment in both groups. STATISTICAL ANALYSIS: The Wilcoxon signed-rank test was used to compare inflammatory biomarkers before and after CPAP therapy. P < 0.05 considered statistically significant. The analysis was performed using SPSS. RESULTS: Recruited patients (n = 47), 51% (n = 24) had OSA and 49% (n = 23), had OSA with asthma. Interestingly, the blood levels of IL-17 and IL-8 were significantly decreased post-CPAP therapy in OSA patients, whereas IL-4, IL-17, and IFN-γ were significantly reduced post-CPAP treatment in OSA patients with asthma. Remarkably, CPAP therapy improved glucocorticoid responsiveness in asthmatic patients with OSA, but not in the OSA group and an increase in the GR-α/GR-β ratio was noted post-CPAP therapy. CONCLUSIONS: Continuous positive airway pressure therapy improved responsiveness to glucocorticoid treatment and demonstrated a suppressive effect on proinflammatory cytokines in asthmatics with OSA.