Charles Persoz

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 TNFalpha (1 ng/mL) sensitization. 24h 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 < or =50 microg/m(3). After TNFalpha 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.

Inflammatory response modulation of airway epithelial cells exposed to formaldehyde

The two main difficulties when assessing the role and action mechanism of environmental pollutant exposure on the respiratory tract using in vitro methodology are firstly to create exposure conditions that closely mimic the human situation, and secondly to choose an experimental model that accurately represents lung compartment complexity, with different types of cell interaction. The aim of this study was to resolve these two challenges. The first of our difficulties was to find the closest experimental conditions to mimic respiratory environmental pollutant exposure. We compared the effects of formaldehyde (FA) on two cellular models, alveolar and bronchial cell lines, respectively A549 and BEAS-2B. The cells were exposed for 30 min to an environmental dose of gaseous FA (50 μg/m³) at the air-liquid interface. In order to mimic macrophage-epithelial cell cooperation, sensitizations (with TNFα or with conditioned medium from macrophages--CM) prior to gas exposure were applied. After toxicity evaluation, local inflammation was assessed by IL-8 and MCP-1 production 24h after exposure. In our experimental conditions FA had no effects on alveolar and bronchial epithelial cells without any sensitization. FA exposure after TNFα sensitization alone induced a moderate increase of IL-8 by A549 cells. After sensitization with CM, FA exposure induced a strong increase of IL-8 production by A549 cells in comparison to air, whereas a decrease of MCP-1 production was observed on BEAS-2B cells. It appears that the response of alveolar and bronchial epithelial cells to FA was moderate and that complex sensitization refines the inflammatory response to environmental stresses. When sensitized with CM, these cell lines responded differently to FA exposure. Finally by interacting with the respiratory epithelium, FA could exacerbate the inflammation of airways that occurs in severe asthma, and even synergize the effects of other air pollutants such as allergens. Evaluation of nasal cell inflammatory response could shed further light on the effects of FA on respiratory epithelium.

Sequential air–liquid exposure of human respiratory cells to chemical and biological pollutants

Although indoor air has wide ranging effects on human health, the effects of environmental, chemical, and biological pollutants on the respiratory system are not fully understood. In order to clarify the health effects of airborne pollutant exposure, it would appear that toxicological evidence is needed to complement epidemiological observations to support by providing biological plausibility. The aim of this study is to manage air-liquid successive exposures to different pollutants such as a chemical pollutant (formaldehyde--FA), and a biological contaminant (Aspergillus fumigatus--Asp) using our in vitro model. Human alveolar cells (A549) were exposed at the air-liquid interface in an exposure module, firstly to an environmental level of FA (50 μg/m³) (or air) for 30 min, and 14 h later to Asp (7×10⁸ spores/m³) (or air) for 30 min. After 10 h post-incubation, cellular viability was assessed. Inflammation biomarkers (IL-8, MCP-1) were assayed by ELISA and by RT-PCR. Whatever the conditions, no cytotoxic effect was observed. FA followed by air exposure did not induce modification of production and expression of cytokines, confirming results with a unique FA exposure. Air followed by Asp exposure tended to induce IL-8 expression whereas IL-8 production tended to increase after FA and Asp exposure compared to FA and air exposure. The reaction of cells to sequential exposure to FA and Asp was moderate. These results show the feasibility of our model for sequential exposures to different types of environmental pollutants, allowing using it for preliminary assessment of cellular activity modification induced by airborne contaminants.