Non-invasive evaluation of lower airway inflammation in hyper-responsive elite cross-country skiers and asthmatics

AbstractAsthma-like symptoms and bronchial hyper-responsiveness (BHR) to methacholine are prevalent in competitive cross-country skiers. Whether these symptoms (ski asthma) in these athletes are caused by asthma remains uncertain.Bronchial responsiveness to adenosine 5′-monophosphate (AMP) and nitric oxide (NO) concentration in exhaled air, both indirect markers of asthmatic airway inflammation, were investigated in two non-smoking study populations of skiers and asthmatics.Of 18 skiers with ski asthma, 15 non-steroid and 14 steroid-treated asthmatics, BHR to AMP was present in five (28%), six (40%) and 10 (71%) subjects respectively. Although the groups were not significantly different in responsiveness to methacholine, responsiveness to AMP increased in order of magnitude from ski asthma < non-steroid-treated < steroid-treated asthma. Exhaled NO in 44 (nine with ski asthma) skiers was not significantly different from 82 healthy non-atopic controls [median [interquartile range (IQR)] 6·5 (4·1–9·9) vs. 5·2 (4·2–6·5) ppb]. Exhaled NO in 29 subjects with mild intermittent asthma was three-fold greater [median (IQR) 19·2 (5·1–25·6) ppb, P<0·01] than in skiers. Exhaled NO was two- and four-fold greater in atopic than non-atopic subjects in the skier (P<0·001) and asthmatic (P<0·01) groups, respectively, and was correlated to methacholine responsiveness in atopic asthmatics (n = 22, rho = 0·55, P < 0·01).Exhaled NO was not elevated in ski asthma and may be more useful as a marker of atopic status than inflammation in the lower airway in skiers. Few skiers were hyper-responsive to AMP, indicating that pre-activated mucosal mast cells are not a predominant feature in ski asthma