CFTR and airway hyperresponsiveness: Overall, the results of this study indicated that PM2.5 exposure inhibited the transepithelial anion Isc by downregulating P2Y2R/CFTR pathway and P2Y2/calcium-dependent chloride channel, and this process may participate in aggravating the airway hyperresponsiveness, airway inflammatory, collagen deposition and hyperplasia of goblet cells.