An in vitro model to evaluate the inflammatory response after gaseous formaldehyde exposure of lung epithelial cells

Asthma is a public health problem worldwide, and indoor air pollution considered to be a potential etiology. New tools need to be developed to study the effects of air pollutants in vitro and modelize inhalation exposure. This study was thus set up to design an in vitro model, using a direct exposure device to study the cellular effects of air pollutants at environmental doses on lung epithelial cells, and apply this to gaseous formaldehyde (FA). A549 cells were exposed using the direct exposure device (air/liquid interface) to FA without, after and before TNFα (1 ng/mL) sensitization. 24 h after exposure, cellular viability (XTT) and inflammation (IL-6, IL-8 and MCP-1) were assessed. No effects on cellular viability were observed for concentrations ≤50 μg/m3. After TNFα sensitization, FA-exposure induced a significant increase in IL-8 (p < 0.001), which could lead to the initiation or pathogenesis of non-specific respiratory inflammation. The results of this study demonstrate the feasibility and sensitivity of the exposure system for testing inflammatory cellular effects of indoor gaseous compounds at environmental doses directly on human respiratory cells.