Modification of gut and airway microbiota on ozone-induced airway inflammation

Ground-level ozone (O₃) has been shown to induce airway inflammation, the underlying mechanisms remain unclear. The aim of this study was to determine whether gut and airway microbiota dysbiosis, and airway metabolic alterations were associated with O₃-induced airway inflammation. Thirty-six 8-week-old male C57BL/6 N mice were divided into 2 groups: sterile water group and broad-spectrum antibiotics group (Abx). Each group was further divided into two subgroups, filtered air group (Air) and O₃ group (O₃), with 9 mice in each subgroup. Mice in the Air and O₃ groups were exposed to filtered air or 1 ppm O₃, 4 h/d for 5 consecutive days, respectively. Mice in Abx + Air and Abx + O₃ groups were exposed to filtered air or O₃, respectively, after drinking broad-spectrum Abx. 24 h after the final O₃ exposure, mouse feces and bronchoalveolar lavage fluids (BALF) were collected and subjected to measurements of airway oxidative stress and inflammation biomarkers, 16S rRNA sequencing and metabolite profiling. Hematoxylin-eosin staining of lung tissues was applied to examine the pathological changes of lung tissue. The results showed that O₃ exposure resulted in airway oxidative stress and inflammation, as well as gut and airway microbiota dysbiosis, and airway metabolism alteration. Abx pre-treatment markedly changed gut and airway microbiota and promoted O₃-induced metabolic disorder and airway inflammation. Spearman correlation analyses indicated that inter-related gut and airway microbiota dysbiosis and airway metabolic disorder were associated with O₃-induced airway inflammation. Together, inhaled O₃ causes airway inflammation, which may implicate gut and airway microbiota dysbiosis and airway metabolic alterations.