Ozone exposed epithelial cells modify cocultured natural killer cells

Muller L, Brighton LE, Jaspers I. Ozone exposed epithelial cells modify cocultured natural killer cells. Am J Physiol Lung Cell Mol Physiol 304: L332-L341, 2013. First published December 14, 2012; doi:10.1152/ajplung.00256.2012.-Ozone (O-3) causes significant adverse health effects worldwide. Nasal epithelial cells (NECs) are among the first sites within the respiratory system to be exposed to inhaled air pollutants. They recruit, activate, and interact with immune cells via soluble mediators and direct cell-cell contacts. Based on our recent observation demonstrating the presence of natural killer (NK) cells in nasal lavages, the goal of this study was to establish a coculture model of NECs and NK cells and examine how exposure to O-3 modifies this interaction. Flow cytometry analysis was used to assess immunophenotypes of NK cells cocultured with either air- or O-3-exposed NECs. Our data show that coculturing NK cells with O-3-exposed NECs decreased intracellular interferon-gamma (IFN-gamma), enhanced, albeit not statistically significant, IL-4, and increased CD16 expression on NK cells compared with air controls. Additionally, the cytotoxicity potential of NK cells was reduced after coculturing with O-3-exposed NECs. To determine whether soluble mediators released by O-3-exposed NECs caused this shift, apical and basolateral supernatants of air- and O-3-exposed NECs were used to stimulate NK cells. While the conditioned media of O-3-exposed NECs alone did not reduce intracellular IFN-gamma, O-3 enhanced the expression of NK cell ligands ULBP3 and MICA/B on NECs. Blocking ULBP3 and MICA/B reversed the effects of O-3-exposed NECs on IFN-gamma production in NK cells. Taken together, these data showed that interactions between NECs and NK cells in the context of O-3 exposure changes NK cell activity via direct cell-cell interactions and is dependent on ULBP3/MICA/B expressed on NECs.