Airway Inflammation in Exercise-Induced Bronchospasm Occurring in Athletes Without Asthma

Exercise-induced bronchospasm (EIB) occurs in athletes with and without asthma. Studies have suggested an inflammatory basis for EIB in asthmatics; however whether inflammation plays a similar role in EIB in athletes without asthma remains unclear. Our objective was to determine whether there is evidence of an inflammatory basis for exercise-induced bronchospasm occurring in non-asthmatic athletes. Ninety-six athletes without asthma from varsity college teams underwent eucapnic voluntary hyperventilation testing. Sputum was induced from subjects with hypertonic saline inhalation post-eucapnic voluntary hyperventilation testing and was analyzed with enzyme-linked immunosorbent assays for IL-5, IL-8, IL-13, cysteinyl-leukotrienes, prostaglandin E2, histamine, leukotriene B4, and thromboxane B2. In addition, inflammatory (neutrophils, lymphocytes, eosinophils, and macrophages) and epithelial cell counts in sputum were recorded. Multivariate regression modeling showed a significant correlation between concentrations of select inflammatory mediators after eucapnic voluntary hyperventilation testing and severity of EIB. Means of the log-transformed concentrations of inflammatory mediators in EIB-positive athletes were significantly higher post-eucapnic voluntary hyperventilation than in EIB-negative athletes. Similar findings were not demonstrated with inflammatory cells. Concentrations of inflammatory mediators are higher in EIB-positive athletes than in EIB-negative athletes without asthma after eucapnic voluntary hyperventilation testing. The severity of EIB in our cohort also is significantly correlated with increased concentrations of select inflammatory mediators suggesting a potential inflammatory basis for EIB in athletes without asthma.