Assessing the Adverse Impacts of PM2.5 on Olfactory System Using an Air-liquid Interface Culture Model of Primary Olfactory Epithelial Cells

The air-liquid interface(ALI) culture is a kind of recently developed system, which has proved its availability in simulating the biology of respiratory tract epithelial tissues. In this study, an ALI-based mouse primary olfactory epithelial cell(OEC) model was established to perform the exposure of PM2.5 (PM=particulate matter) collected from Dianshan Lake(Shanghai) and Wangdu(Hebei). The results showed that PM2.5 in both regions caused a decrease in cell viability in a dose-dependent manner. The 0.5 and 5 µg/cm2(around ambient concentrations) of PM2.5 disrupted OEC membrane integrity and produced oxidative stress with elevated indicators of malondialdehyde(MDA) and reactive oxygen species(ROS). In transcriptomic sequencing, the terms concerning inflammatory cytokines and second messenger cyclic adenosine-3′,5′-monophoshate(cAMP) were enriched in two treatments. The cytokine array showed the levels of some cytokines were altered, although inflammatory responses may not remarkably occur. Meanwhile, PM2.5 disturbed cAMP contents and key genes in the cAMP signaling pathway. The effects of PM2.5 of both regions were largely consistent, while Wangdu samples caused more ROS and Dianshan Lake samples tended to induce inflammatory injury. Thus, with the application of a novel ALI-based in vitro OEC model, our study demonstrated that ambient PM2.5 has the ability to threaten the physiologies and functions of the olfactory system.