Metabolomics applied to exhaled breath condensate in childhood asthma

RATIONALE: Metabolomic analysis provides biochemical profiles of low-molecular-weight endogenous metabolites in biological fluids. OBJECTIVES: The aim of this study was to assess the feasibility of nuclear magnetic resonance (NMR)-based metabolomic analysis applied to exhaled breath condensate ("breathomics"). Information coming from NMR spectra was analyzed with a view to establish the NMR variables that best discriminate between children with asthma and healthy children. METHODS: Twenty-five children with asthma (17 with persistent asthma treated with inhaled corticosteroids, 8 with intermittent asthma inhaled corticosteroid naive; age, 7-15 yr) and 11 healthy age-matched control subjects were enrolled. Every child performed exhaled nitric oxide measurement, spirometry, and condensate collection. Condensate samples were analyzed by means of NMR spectroscopy. Linear and partial least squares discriminant analyses were applied to data obtained from the NMR spectra. MEASUREMENTS AND MAIN RESULTS: The combination of exhaled nitric oxide and FEV(1) discriminates children with asthma and healthy children with a success rate of approximately 81%, whereas selected signals from NMR spectra offer a slightly better discrimination (approximately 86%). The selected NMR variables derive from the region of 3.2 to 3.4 ppm, indicative of oxidized compounds, and from the region of 1.7 to 2.2 ppm, indicative of acetylated compounds. CONCLUSIONS: Metabolomics can be applied to exhaled breath condensate, leading to the characterization of airway biochemical fingerprints. The presence of acetylated compounds suggests new metabolic pathways that may have a role in asthma pathophysiology.