December 12th, 2017
Airborne particulate matter (PM) is hypothesized to play a role in increases in ashtma prevalence, although a casual relationship has yet to be established. To investigate the effects of real-world PM exposure on airway reactivity (AHR) and bronchoalveolar lavage (BAL) cellularity, we exposed naive mice to a single does (0.5 mg/mouse) of ambient PM, coal fly ash, or diesel PM. We found that ambient PM exposure induced increases inARH and BAL cellularity, whereas diesel PM induced significant increases in BAL cellularity, but notARH. On the other hand, coal fly ash exposure did not elicit significant changes in either of these parameters. We further examined ambient PM-induced temporal changes inARH, BAL cells, and lung cytokine levels over a 2-week period.Ambient PM-inducedAHR was sustained over 7 d. The increase inAHR was preceded by dramatic increases in BAL eosinophils, whereas a decline inAHR was associated with increases in macrophages.A Th2 cytokine pattern (IL-5, IL-13 eotaxin) was observed early on with a shift toward a Th1 pattern (IFN-y). In additional studies, we found that the active component(s) of ambient PM are not water-soluble and that ambient PM-inducedAHR and inflammation are dose-dependent. We conclude that ambient PM can induce asthmalike parameters in naive mice, suggesting that PM exposure may be an important factor in increases in asthma prevalence. Keywords: air pollution; allergy, asthma; inflammation