Investigating allergen-induced acute lung inflammation in asthmatic individuals using breath biopsies

Lung inflammation releases volatile organic compounds (VOCs) and occurs in several illnesses, and as a response to pollution and other irritants. VOCs in breath could be a tool to non-invasively detect and monitor inflammation. Breath (via Breath Biopsy) is used as such to discover and monitor biomarkers of exposure, metabolism, and disease. We investigated VOCs in exhaled breath associated with lung inflammation induced by an allergen challenge, the hypothesis being that exposure to a mild allergen induces inflammation of epithelial lung tissue and this will result in the production of specific VOCs in exhaled breath. Eleven asthmatic individuals participated in a randomized, controlled, double-blind, crossover study including 2 challenge sessions using a GC-MS approach to analyse samples from 7 timepoints. Breath samples were compared to blanks to assess VOCs on breath relative to those present in ambient air. Analysis involved an untargeted method and targeted analysis of 30 compounds. VOCs in exhaled breath showed statistically significant differences between pre- and post-challenge samples (8 from targeted panel, p-value <0.05). Moreover, several VOCs in exhaled breath showed significant correlation with blood and sputum inflammatory markers, indicating that VOCs relate to inflammation in lungs. In conclusion, we show that VOC profiles can be detected in breath from individuals exposed to inflammation triggers, suggesting that VOCs in exhaled breath could provide a means to detect acute airway inflammation. This study adds to the evidence that breath can be used to measure VOCs associated with different phenotypes, in this case healthy vs asthma.