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COMPARISON OF ON AND OFF ROAD DIESEL EXHAUST SOURCES ON THE SUSCEPTIBILITY TO AN INFLUENZA INFECTION.
Citation:
GOWDY, K., J. CIENCEWICKI, I. JASPERS, E. BOYKIN, AND M. I. GILMOUR. COMPARISON OF ON AND OFF ROAD DIESEL EXHAUST SOURCES ON THE SUSCEPTIBILITY TO AN INFLUENZA INFECTION. . Presented at Society of Toxicology Annual Meeting, Charlotte, NC, March 25 - 29, 2007.
Description:
Diesel exhaust (DE), a major component of urban air pollution, and its modulatory role in human susceptibility to respiratory infections is of great concern. The purpose of this study was to evaluate the effects of on- and off-road sources of DE exposure on the severity of an acute influenza infection in vivo. BALB/c mice were exposed 4 hrs/day to air or 0.5 mg/m3 of DE from an engine powering an air compressor or a diesel truck for 5 days. One hour after the final diesel exposure, mice were intratracheally instilled with 10 HA units of influenza A/Bangkok/1/79 virus. 18 hours later animals were sacrificed and lung tissue and bronchoalveolar lavage (BAL) fluid were collected. HA RNA, a marker of viral levels, IFN-ß, IL-6, surfactant protein A and D (SP-A and SP-D) mRNA levels were determined by real-time RT-PCR. Lung injury was assessed by differential cell counts, and the production of LDH (U/l), microalbumin (¿g/ml), and protein (¿g/ml) in the BAL. Exposure to 0.5 mg/m3 DE from either source increased influenza-induced lung injury, as indicated by enhanced levels of protein, neutrophil recruitment and total cell counts in the BAL. Both sources of DE had a significant enhancement of IFN-ß. However, mice exposed to the compressor had significantly higher viral HA RNA, suggesting greater viral proliferation, which was not seen with mice exposed to the diesel truck. Exposure to compressor DE decreased the production of SP-A and SP-D in both the influenza and control exposed animals. The decrease of surfactant protein production was not seen in the mice exposed to the diesel truck which correlated with a lack of enhancement of viral levels. We conclude that exposure to moderate levels of DE (0.5 mg/m3) from an off road source decreases the production of SP-A and SP-D in association with increased influenza levels and lung injury. (Funded by EPA CT829470. This abstract does not reflect EPA policy).