Diesel exhaust particles potentiate allergic Th2/Th17 recall responses (HYP7P.301)

Abstract

Abstract Diesel exhaust particles (DEP) are a major component of traffic related air pollution and have been implicated in asthma exacerbations. In mice intra-tracheally exposed 9 times over the course of 3 weeks to either saline, DEP, house dust mite (HDM) or HDM and DEP, we assessed the rate of DEP clearance from the lung and examined its impacts on HDM recall responses. DEP alone did not induce the classic hallmarks of asthma but promoted a Th17 response resulting in long lasting chronic neutrophilia. DEP was still observed in a majority of alveolar macrophages 6 weeks after exposure. Coexposures to HDM and DEP generated a mixed Th2/Th17 response with a more severe asthma phenotype that completely resolved within 4 weeks. However, upon in vitro restimulation with HDM, Th2/Th17 responses were significantly enhanced in lung and draining lymph node cell cultures of HDM+DEP exposed mice compared to mice exposed to HDM alone. In conclusion, the prolonged presence of DEP in the lungs is associated with chronic neutrophilia. DEP-mediated exacerbation of allergen-induced asthma promotes long-term expansion of effector/memory Th17 and Th2 populations.