Assessment of biological responses of EpiAirway 3-D cell constructs versus A549 cells for determining toxicity of ambient air pollution

Context: EpiAirway (TM) 3-D constructs are human-derived cell cultures of differentiated airway epithelial cells that may represent a more biologically relevant model of the human lung. However, limited information is available on their utility for exposures to air pollutants at the air-liquid interface (ALI). Objective: To assess the biological responses of EpiAirway (TM) cells in comparison to the responses of A549 human alveolar epithelial cells after exposure to air pollutants at ALI. Methods: Cells were exposed to filtered air, 400 ppb of ozone (O-3) or a photochemically aged Synthetic Urban Mixture (SynUrb54) consisting of hydrocarbons, nitrogen oxides, O-3 and other secondary oxidation products for 4h. Basolateral supernatants and apical washes were collected at 9 and 24h post-exposure. We assessed cytotoxicity by measuring lactate dehydrogenase (LDH) release into the culture medium and apical surface. Interleukin 6 (IL-6) and interleukin 8 (IL-8) proteins were measured in the culture medium and in the apical washes to determine the inflammatory response after exposure. Results: Both O-3 and SynUrb54 significantly increased basolateral levels of LDH and IL-8 in A549 cells. No significant changes in LDH and IL-8 levels were observed in the EpiAirway (TM) cells, however, IL-6 in the apical surface was significantly elevated at 24h after O-3 exposure. Conclusion: LDH and IL-8 are robust endpoints for assessing toxicity in A549 cells. The EpiAirway (TM) cells show minimal adverse effects after exposure suggesting that they are more toxicologically resistant compared to A549 cells. Higher concentrations or longer exposure times are needed to induce effects on EpiAirway (TM) cells.