Research On The Cellular Toxicity Of BEAS-2B Cells After In Vitro Air-liquid Interface Exposure To Air Pollution Mimics:Sulfate-loaded Aerosol Particles

With carrying various toxic pollutants,particulate matter（PM）in the atmosphere could cause adverse effects from human inhalation exposure through respiratory system.However,it is not easy to clearly define the toxicity contribution of individual pollution component from the complex mixture of air pollution.Silica is one of the major components in atmosphere particle matter and bisulfite is the main component as derivatives of sulfur dioxide.In this context,we simulated atmospheric particulate component by using the sulfate-loaded silica to clarify the compound toxicity.In this study,we used silica particles loaded with bisulfite ions to simulate the sulphate components contained in atmospheric particulates.We studied the effects of aerosol exposure under conditions close to atmospheric real exposure conditions,and explored its possiblemechanism of compound toxicity.The silica particles formed an aerosol for 3 h to simulate the actual exposure conditions of air pollution.The acute toxicity of aerosols to cells was assessed by measuring cell viability and cell integrity 3 h after ALI exposure;aerosol live-cell mortality and cell production were assessed after 3 h of ALI exposure and 5 h of culture under conventional immersion conditions.The aim of this study is to generate aerosol and evaluate the potential adverse effects of sulfate-loaded silica nanoparticles（NPs）by the air-liquid interface（ALI）cell exposure assay.BEAS-2B cells were exposed to either nano-SioO2 or bisulfite aerosol alone,or sulfate-loaded silica for 3 h by a commercialized exposure chamber（CULTEX（?）Radial Flow System Compact）with the purpose to simulating the realistic exposure scenario of atmospheric pollution components.The cell viability was assessed after 3 h’s ALI exposure for evaluating the direct acute toxicity.Oxidative stress levels,ATP content,cell apoptosis ratesendoplasmic and endoplasmicreticulum stress level were evaluated at 8 h after ALI exposure.After ALI exposure for 3 h and cultured at submerge conditions for 9 h,proteins were collected and detected the expression about cell apoptosis by Western blotting.With the cell exposure experiments,the particle size and the particle number concentration of aerosols were detected in real time via instruments SMPS（Scanning Mobility Particle Sizer）and CPC 3007（Condensation Particle Counters 3007）.The toxicities of different NMs were thoroughly compared based on the deposited dosages of aerosol on surface of cells.The ALI exposure of SiO₂ NPs alone produced less cytotoxicity in the BEAS-2B cells,but the sulfate-loaded silica exposure significantly decreased the cell viability and enhanced the cellular reactive oxygen species（ROS）and induced apoptosis of the endoplasmic reticulum and the mitochondrial pathway,and havea certain dose-effect relationship with the concentration of HSO₃.ALI exposure has a high possibility toreflect the realistic physiological exposure conditions of the human respiratory system.The present study indicates that the sulfate,the derivative of sulfur dioxide component in the air pollution,exacerbates the toxic effects of the inhalable PMs.These evidences of toxicity contributions from these components illustrate that much more attention should be paid on the strict control of emissions of sulfur dioxide.Further,more researches on the chronic exposure are needed to reveal further insight into the fate of sulfate-loading silica after cellular deposition and interactions with the cell.