Airway cytokine expression measured by means of protein array in exhaled breath condensate: Correlation with physiologic properties in asthmatic patients

Background: Simultaneous monitoring of airway inflammation and physiology might be useful for asthma management. Objective: We examined the upregulated molecules in asthmatic airways. Furthermore, we investigated the relationship between these molecules and the airway physiologic properties of asthma. Methods: Ten nonsmoking healthy subjects and 16 steroid-naive asthmatic patients were enrolled. Exhaled breath condensate (EBC) sampling, spirometry, and methacholine inhalation challenge were performed on one occasion in this cross-sectional study. Peak expiratory flow was also measured for 4 weeks. Airway cytokine-chemokine-growth factor production was analyzed with a protein array. Results: The expressions of IL-4, IL-8, IL-17, TNF-alpha, RANTES, IFN-gamma-inducible protein 10, TGF-beta, and macrophage inflammatory protein la and 10 were significantly upregulated in asthmatic airways compared with those of nonsmoking healthy subjects. Among the upregulated molecules; RANTES expression was significantly correlated with the parameters that represent airway caliber, FEV1 and respiratory resistance values. In addition, the levels of both TNF-a and TGF-beta were significantly correlated with the methacholine threshold and peak expiratory flow variability for the week. Conclusion: Inflammatory molecule analysis with EBC appeared to be useful for monitoring the asthmatic airway condition. Clinical implications: Measurements of cytokine levels in EBC might be a promising approach to assess the efficacy of pharmacologic interventions and to investigate the pathophysiology of asthma.