Spatial and Temporal Distribution Characteristics and Cytotoxicity of Atmospheric PM2.5 in the Main Urban Area of Lanzhou City.

Abstract

PM_2.5, as one of the most harmful pollutant in the atmospheric environment and population health, has received much attention. We monitored PM_2.5 levels at five sampling sites in the Lanzhou City and collected PM_2.5 particles from two representative sites for cytotoxicity experiment. The cytotoxicity of PM_2.5 samples on A549 cells and migration ability of the cells were respectively detected by Cell Counting kit-8 (CCK-8) assay and scratch assay. We detected the levels of cellular inflammatory factors and oxidative damage-related biochemical indexes. RT-qPCR was used to detect the mRNA levels of NF-κB and epithelial-mesenchymal transition (EMT)-related genes. We found that the Lanlian Hotel station had the highest PM_2.5 annual average concentration. The annual average concentration change curve of PM_2.5 showed a roughly "U"-shaped distribution during the whole sampling period. The cytotoxicity experiment showed the viability of A549 cells decreased and the scratch healing rate increased in the 200 and 400 μg/mL PM_2.5-treated groups. We also found 400 μg/mL PM_2.5 induced changes in the mRNA levels of NF-κB and EMT-related genes, the mRNA levels of IKK-α, NIK, and NF-κB in the 400 μg/mL PM_2.5 group were higher than those in the control group. The mRNA levels of E-cadherin decreased and α-SMA increased in the 400 μg/mL PM_2.5 groups, and the mRNA levels of Fibronectin increased in the 400 μg/mL PM_2.5 groups. Moreover, we found hydroxyl radical scavenging ability and T-AOC levels were lower, and LPO levels were higher in the 200 and 400 μg/mL PM_2.5 groups, and the SOD activity of cells in the 400 µg/mL PM_2.5 group decreased. And compared with the control group, the levels of TNF-α were higher in the 200 and 400 μg/mL PM_2.5 groups and the levels of IL-1 were higher in the 400 μg/mL PM_2.5 group. The results indicated that the cytotoxicity of atmospheric PM_2.5 was related to oxidative damage, inflammatory response, NF-κB activity and EMT.