A new coculture-system of bronchial epithelial and endothelial cells as a model for studying ozone effects on airway tissue.

In order to study the inflammatory potential of ozone on the airway tissue, we developed an in vitro model system in which human bronchial epithelial cells (BEAS 2B) and human umbilical vein endothelial cells (ECV304) were able to communicate with each other. The BEAS 2B cells were grown on filter supports which were inserted into six-well culture dishes. Endothelial cells were cultivated on the bottom of the basolateral compartment. The upper epithelial cells were exposed to 0.15 ppm ozone for 90 min. Supernatants were collected after 1, 4 and 24 h and were quantified for IL-6 and IL-8 secretion. At the same time points we measured the expression of ICAM-1 on the umbilical vein endothelial cells. Exposure of the coculture-system to air or ozone induced the production of IL-6 as well as IL-8 that exceeded the sum of the amounts produced by the two cell types when exposed separately. At 24 h after ozone exposure the IL-6 and IL-8 levels were significantly elevated compared with the air treated cells. Concerning the ICAM-1 expression on ECV304 cells we found elevated ICAM-1 levels on cells which had been cocultured with BEAS 2B cells compared with cells cultured alone. This might be a hint for the secretion of a soluble factor that acts as a mediator in amplifying the response of epithelial cells.