The cellular effects of PM2.5 collected in Chinese Taiyuan and Guangzhou and their associations with polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs and hydroxy-PAHs

Numerous studies have demonstrated adverse effects on human health after exposure to fine particulate matter (PM2.5). However, it is still not clear how the toxicological effects and the health risks vary among PM samples of different compositions and concentrations. In this study, we examined effects of region- and season-dependent differences of PM2.5 on cytotoxicity, and the contributions of PAHs, nitro-PAHs (N-PAHs) and hydroxy-PAHs (OH-PAHs) to PM2.5 toxicity by determining different toxicological indicators in three lung cell lines. The results illustrated significant differences in components concentrations and biological responses elicited by PM2.5 collected in different cities and seasons. The concentrations of most PAHs, N-PAHs and OH-PAHs were much higher in Taiyuan than in Guangzhou. PM2.5 from Taiyuan exhibited lower cell viability and higher reactive oxygen species (ROS) and interleukin-6 (IL-6) release on lung cells than those from Guangzhou. Specifically, PM2.5 collected in summer from Taiyuan caused higher levels of pro-inflammatory responses and oxidative potential than those collected in winter. The correlation analysis between 19 PAHs, 17 N-PAHs and 12 OH-PAHs and the measured indicators demonstrated that PAHs were more related to PM2.5-induced CCK-8 cytotoxicity and IL-6 release in Taiyuan while N-PAHs and OH-PAHs were more related to PM2.5-induced CCK-8 cytotoxicity and dithiothreitol (DTT)-based redox activity in Guangzhou, suggesting that the toxicity of PM2.5 from Taiyuan was mostly correlated with PAHs while the toxicity of PM2.5 from Guangzhou was closely associated with N-PAHs and OH-PAHs. These results revealed that composition differences in PM2.5 from different regions and seasons significantly accounted for the differences of their toxicological effects.