Inflammatory metabolites in exhaled breath condensate characterize the obese respiratory phenotype

In humans, obesity plays a critical role in pulmonary inflammation, and is an important risk factor for the development of several inflammatory respiratory diseases. Therefore, understanding the mechanisms that generate mediators in the setting of obesity may help to recognize the link between obesity and chronic respiratory diseases, like the increased incidence and severity of asthma in obese individuals. NMR spectroscopy of exhaled breath condensate (EBC, a non-invasive matrix to access the lung epithelial lining fluid) can unambiguously identify biomarkers characterizing different pulmonary physiopathological states. In this study we aimed at verifying if NMR-based metabolomics of EBC, combined with orthogonal projections to latent structures-discriminant analysis, could possibly recognize specific biomarkers to map the obese metabolic respiratory phenotype. Obese and lean control subjects could be distinguished in a statistical model presenting high quality parameters (R2 = 0.904 and Q2 = 0.871). Identified airway metabolites linked to the inflammation processes demonstrate that obesity constitutes a specific inflammatory metabolic phenotype (metabotype). It is concluded that the noninvasive EBC matrix is suitable to selectively investigate the obesity-related lung inflammation.