Is Asthma in Athletes A New Asthma Phenotype?

Abstract

RATIONALE: High prevalence of asthma has been detected in athletes compared with non-athletes asthmatic subjects (NAAS). Elite athletes presented more airway hyperresponsiveness to methacholine than NAAS. However, underlying mechanisms are unknown. Our objectives were to evaluate differences in immunological and cellular mechanisms and to study functional characteristics in these patients. METHODS: Athletes with physician-diagnosed asthma were classified in two groups: athletes with positive indirect methods (APIM; manitol and/or eucapnic voluntary hyperventilation; n=16) and athletes with negative indirect methods (ANIM) but positive methacholine (n=8). Moreover, NAAS (n=23) and healthy control subjects (HCS, n=13) were recruited. Induced sputum was done in all patients and cell analysis of this sample was performed by flow cytometry. RESULTS: All asthmatic subjects showed eosinophilia respect to HCS. Also, APIM showed lower eosinophil percentage than NAAS (P<0.001). Basophils percentage was higher in APIM than NAAS and HCS (P<0.01). Similar result was observed in lymphocytes percentage. It was more elevated in APIM than NAAS (P<0.0001), although this value was very similar to percentage observed in HCS. Neutrophils were increased in APIM as compared with other groups. No differences were observed when cell count was compared before and after the bronchial challenge in athletes. CONCLUSIONS: Inflammatory infiltrate from APIM is different from observed in NAAS. Athletes with asthma presented a lower eosinophilila than NAAS, but an increased basophils and lymphocytes percentage. These results could implicate a different mechanism underlying to physical athlete condition, with own phenotypic characteristics.