Changes in the lung microbiota in mice exposed to air pollutants

Background: Environmental microbes are associated with both protective and adverse lung effects in chronic lung disease. Although the role of the gut microbiome in human health has been relatively well studied, the role of the respiratory microbiome in the response to inhaled pollutants is largely unknown. Objective: Our aim was to characterize the bacterial microbiome in lung samples collected in mice exposed to nanoparticles. Method: Mice were exposed to TiO2 nanoparticles using an ultrasonic nebulizer. We determined the composition of the microbial communities present in lung samples by amplifying and sequencing regions of the 16S rRNA gene from bacteria. Results: Airway inflammation and responsiveness were correlated with the lung microbiota. Relative to the controls, mice exposed to TiO2 nanoparticles exhibited increased hyper-responsiveness and number of inflammatory cells. The abundances of Pseudomonas, Acinetobacter, Brucella, Mesorhizobium, Enhydrobacter, Methylobacterium, Rhizobium, Chryseobacterium, Brevundimonas, Deinococcus, and Micrococcus differed between mice exposed to TiO2 nanoparticles and controls. Deinococcus abundance was significantly increased in TiO2 nanoparticle-exposed mice compared with control mice. The number of airway inflammatory cells was correlated with Deinococcus abundance. Conclusion: Nanoparticles altered the composition of lung microbial taxa, suggesting that exposure to air pollutants causes lung inflammation via alterations in the lung microbiota.