Associations of particulate matter-associated microbial profiles with lung and intestinal microbiomes in healthy mice

Ambient air pollution has detrimental effects on human health. We investigated exposure-related differences and microbial overlap among PM₁, lung, and gut microbiomes in mice exposed to PM₁, high-efficiency particulate air (HEPA)-filtered air, or clean air. PM₁ was characterized for soluble ions, metals, carbonaceous fractions, and oxidative potential, while gaseous pollutants data were obtained from air-quality monitoring stations. PM₁, lung, and gut microbiomes were analyzed using 16S rRNA sequencing, and short-chain fatty acids (SCFAs) were quantified by gas chromatography-mass spectrometry (GC-MS). Proteobacteria was the dominant phylum in PM₁. PM₁ contained diverse chemical constituents, including soluble ions, metals, and oxidative species. Lung microbial diversity remained largely unchanged, whereas the gut microbiome was significantly altered. Compared with control, the PM₁ group showed reduced Actinobacteriota and Bacteroidota, while Campylobacterota and Patescibacteria decreased in both HEPA and PM₁ groups. Verrucomicrobiota increased in the HEPA group, and Proteobacteria increased in the PM₁ group compared with both HEPA and control groups. Correlation analyses identified associations between lung and gut microbiomes, environmental variables, PM₁ characteristics, gaseous pollutants, and SCFAs. Eleven bacterial families and six genera overlapped among PM₁, lung, and gut microbiomes in the PM₁ group. Overall, ambient air pollution was associated with gut dysbiosis in mice.