Source-apportioned coarse particulate matter exacerbates allergic airway responses in mice

Abstract

Exposure to coarse particulate matter (PM) is associated with lung inflammation and exacerbation of respiratory symptoms in sensitive populations, but the degree to which specific emission sources contribute to these effects is unclear. We examined whether coarse PM samples enriched with diverse sources differentially exacerbate allergic airway responses. Coarse PM was collected weekly (7/2009–6/2010) from urban (G.T. Craig [GTC]) and rural (Chippewa Lake Monitor [CLM]) sites in the Cleveland, Ohio area. Source apportionment results were used to pool GTC filter PM extracts into five samples dominated by traffic, coal, steel (two samples), or road salt sources. Five CLM samples were prepared from corresponding weeks. Control non-allergic and house dust mite (HDM)-allergic Balb/cJ mice were exposed by oropharyngeal aspiration to 100 μg coarse GTC or CLM, control filter extract, or saline only, and responses were examined 2 d after PM exposures. In allergic mice, CLM traffic, CLM road salt and all GTC samples except steel-1 significantly increased airway responsiveness to methacholine (MCh) compared with control treatments. In non-allergic mice, CLM traffic, CLM steel-2 and all GTC samples except coal significantly increased bronchoalveolar lavage fluid (BALF) neutrophils, while only CLM traffic PM increased eosinophils in allergic mice. In non-allergic mice, CLM coal PM increased BALF interleukin (IL)-13 and GTC steel-1 PM increased TNF-α levels. These results demonstrate that equal masses of GTC and CLM coarse PM enriched with a variety of sources exacerbate allergic airway disease. Greater PM concentrations at the urban GTC site signify a greater potential for human health effects.