[The utility of exhaled breath condensate analysis for asthma management]

Asthma is a chronic inflammatory disorder of the airways; therefore, establishing a simple monitoring system of airway inflammation would be useful for asthma management. Exhaled breath condensate (EBC), which is formed by breathing with a cooling system, is a non-invasive biomarker for airway inflammation. We have shown that nine kinds of molecules; namely, IL-4, IL-8, IL-17, TNF-alpha, RANTES, IP-10, TGF-beta, MIP-1alpha, and MIP-1beta, are over-expressed in asthmatic airways compared with those of healthy subjects using EBC analysis. In addition, the levels of some over-expressed molecules and lung physiologic indices are correlated. RANTES expression was significantly correlated with the degree of airflow limitation. Further, both TNF-alpha and TGF-beta values were significantly correlated with the degree of airway responsiveness and variability of peak expiratory flow. Additionally, the comparison of molecular properties between EBC and saliva indicated that saliva contamination is not a dominant contributor to the assessment of inflammatory molecules in EBC. Analysis of inflammatory molecules using EBC should be useful for monitoring the asthmatic airway condition, and might be a promising approach to assess the efficacy of pharmacologic interventions and to investigate the pathophysiology of asthma.