DNA and Chromosome Damage in BEAS-2B Cells Following Air-Liquid Interface Exposure to Whole Gasoline Engine Exhaust

Whole-component gasoline engine exhaust (GEE) has been classified as possibly carcinogenic to humans, where DNA and chromosome damage may play a key role. This study evaluated DNA and chromosome damage induced by GEE in human bronchial epithelial BEAS-2B cells using an air-liquid interface (ALI) exposure system. Following exposure to GEE at different dilution ratios, the cell relative viability (CRV), the percentage of DNA in the comet tail (TailDNA%), γ-H2AX protein expression, and chromosome damage for BEAS-2B cells were assessed using the Cell Counting Kit-8 (CCK-8) assay, the alkaline comet assay, Western Blotting, and cytokinesis-block micronucleus (CBMN) assay, respectively. Results showed that the relative survival rate of BEAS-2B cells decreased progressively with increasing GEE concentration (decreasing dilution ratios); specifically, a significant reduction was observed from the 1:10 dilution group onwards. TailDNA% increased significantly in all GEE-exposure groups compared to the clean air control, with a significant difference were observed starting from the 1:10 dilution group. γ-H2AX protein expression exhibited a nonsignificant trend of initial increase followed by a decrease. The cell nuclear division index (NDI) decreased significantly from the 1:5 dilution group onwards. The rates of micronuclei (MN), nucleoplasmic bridges (NPBs), and nuclear buds (NBUDs) increased significantly starting from the 1:10 dilution group, nondiluted GEE group, and 1:20 GEE group, respectively. These findings indicate that GEE exposure induces DNA and chromosome damage in BEAS-2B cells, and γ-H2AX may play a crucial role in DNA repair processes, although the specific mechanisms still require further investigation.