AbstractIntroductionCompetitive cross-country skiers and swimmers present characteristics of airway inflammation and remodeling of the extracellular matrix similar to what is observed in mild asthma. We aimed to compare serum and sputum MMP-9/TIMP-1, reflecting the balance between airway fibrogenesis and inflammation process, in swimmers and winter sport athletes, during the annual period of training resumption, and to observe its seasonal variations in winter sports athletes.MethodsCompetitive winter sports athletes (n=41), swimmers (n=25) and healthy nonathletes (n=8) had blood sampling, lung function measurement, skin prick tests, eucapnic voluntary hyperpnea challenge, methacholine inhalation test (MIT), and induced sputum analysis. Twelve winter sport athletes performed the test during both summer and winter. Serum and sputum MMP-9 and TIMP-1 were measured by ELISA.ResultsNo significant difference in baseline serum or sputum MMP-9/TIMP-1 ratio was observed between the three groups, and no relationship was observed with airway function or responsiveness. Serum MMP-9/TIMP-1 ratio was however significantly higher during the summer in winter sport athletes compared with winter season (median [Interquartile range]: 1.27 [0.97-1.62] during the winter and 3.65 [2.47-4.03] during the summer, p=0.005). Sputum MMP-9 correlated with Methacholine PC20 and serum CC16/SP-D ratio. No significant correlation was observed between serum values and lung function or responsiveness.ConclusionOur results suggest that although MMP-9/TIMP-1 ratio in sputum or serum was similar in our three groups of subjects, it may fluctuate according to the training season while sputum MMP-9 correlated with Methacholine PC20 and serum CC16/SP-D ratio, suggesting a link between airway responsiveness, epithelial damage and MMP-9 in the airways.