Exhaled TGF-1 levels before and after an exercise challenge in asthmatic and healthy children, and during exacerbation

Background: There is conflicting data regarding the role of transforming growth factor-beta 1 (TGF-beta 1) in the pathogenesis of airway hyper-reactivity and asthma exacerbation. Objective: To investigate the role of exhaled-TGF-beta 1 in exercise-induced bronchospasm (EIB) in asthmatic and nonasthmatic healthy children, and in asthma exacerbation and asthma control. Methods: The exhaled-TGF-beta 1 levels of 56 stable asthmatic children and 15 nonasthmatic healthy children were evaluated before and 30 min after an exercise challenge. The exhaled-TGF-beta 1 levels of 20 additional children with asthma exacerbation were evaluated. Results: While no significant difference in the exhaled-TGF-beta 1 levels was found at the baseline, exhaled-TGF-beta 1 levels after the exercise challenge were significantly higher in the non-EIB (n = 31) asthmatics when compared to the asthmatic children with EIB (n = 25) (p = 0.04). Although there was a statistically significant increase in the concentration of the exhaled-TGF-beta 1 after the exercise challenge in the non-EIB asthmatics (p = 0.008), the concentration of the TGF-beta 1 was not increased after the exercise challenge in EIB + asthmatics. The exhaled-TGF-beta 1 was significantly correlated with the ACT score (p = 0.01, r = 0.49) and the baseline FEV1 level (p = 0.02, r = 0.35). The exhaled-TGF-beta 1 levels were significantly higher in the stable asthmatic children when compared to the nonasthmatic children (p < 0.0001). There was no significant difference in exhaled-TGF-beta 1 levels after the exercise challenge in the nonasthmatics. The exhaled-TGF-beta 1 levels were significantly lower in those children with asthma exacerbation when compared to the stable asthmatic children (p = 0.0003). Conclusion: Our results suggest that TGF-beta 1 may play a role in suppressing airway reactivity and its deficiency is associated with asthma exacerbation.