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-α, RANTES, IFN-γ-inducible protein 10, TGF-β, and macrophage inflammatory protein 1α and 1β 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, FEV ₁ and respiratory resistance values. In addition, the levels of both TNF-α and TGF-β 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.