Abstract:

Objective · To observe the changes of lung tissue and lung microbiome in mice after inhalation of vehicle exhaust, and to assess the impact of
air pollution caused by vehicle exhaust on the respiratory system of the population. Methods · Ten C57BL/6 mice were divided into experimental group
and control group randomly. Experimental group was inflicted with continuous exposure to automobile exhaust for 5 d (1 h/d), while the control group was
exposed to clean air. After a 5-day of environmental exposure, the lung microbial composition was analyzed by 16S rRNA pyrosequencing and the structure
of the lung tissue was assessed by histological analysis. Results · There was no significant difference in pathological changes of lung tissue between the
experimental group and the control group. However, there were significant differences in the composition and abundance of bacteria in the experimental
and control groups. At the phylum level, comparing with the control group the Firmicutes was significantly increased in the experimental group, while the
Bacteroidetes and Proteobacteria were significantly reduced. At the genus level, the increase of the Firmicutes was mainly related to the increase of the
Coprococcus. The reduction of the Bacteroidetes was related to the reduction of Cytophaga while the reduction of the Proteobacteria was related to three main strains namely Ochrobactrum, Methylobacterium and Acinetobacter. Amycolatopsis was also reduced significantly. Conclusion · Short-term exposure to vehicle exhaust conditions changes the species composition and abundance of lung microbiome in mice, but no lung tissue lesions were observed.

Key words:  lung microbiome, particulate matter, vehicle exhaust, 16S rRNA