Elsevier

Science of The Total Environment

Volume 533, 15 November 2015, Pages 275-282
Science of The Total Environment

Geogenic PM10 exposure exacerbates responses to influenza infection

https://doi.org/10.1016/j.scitotenv.2015.07.001Get rights and content

Highlights

  • Geogenic PM10 exposure exacerbates the response to a respiratory viral infection.

  • This exposure increases inflammation and viral load, and impairs lung function.

  • Iron content in the particles may be a driver of these responses.

  • This has important implications for lung health in communities in arid environments.

Abstract

Particulate matter (PM) exposure has been linked epidemiologically to exacerbations of lung disease, including respiratory infections. We investigated the effects of geogenic (earth-derived) PM10 (PM < 10 μm diameter) on the response to a respiratory viral infection.

Geogenic dust was sampled from four communities in arid environments in Western Australia. Adult female BALB/c mice were intranasally exposed to chronic doses of PM10 (10 μg/day for 10 days), and/or infected with influenza (A/Mem/1/71) virus. Inflammation (cells, IL-6, IFN-γ) was measured in bronchoalveolar lavage. Lung mechanics were measured using the forced oscillation technique.

Geogenic PM10 induced lung inflammation (neutrophils, macrophages) with additive effects in mice also infected with influenza. PM10 also modified the influenza-induced IL-6 and IFN-γ responses. Geogenic PM10 increased airway resistance, and increased hysteresivity in those exposed to both insults. Viral titres were significantly higher after PM10 exposure. Iron concentration was inversely associated with IFN-γ and positively associated with viral titre and hysteresivity.

Geogenic PM10 exposure increases inflammation, impairs lung function and increases viral load, exacerbating the response to respiratory viral infection. Iron in the particles may be a driver of these responses. This has important implications for respiratory health in communities exposed to high geogenic PM10, such as those in arid environments.

Section snippets

Background

Particulate matter (PM) continues to be the aspect of air pollution that is most reliably associated with human disease; particularly PM with an aerodynamic diameter of < 10 μm (PM10) (Harrison and Yin, 2000). Ambient PM10 concentrations have been associated epidemiologically with increased hospitalisations for respiratory diseases, including lower respiratory tract infections (Lin et al., 2005, Xu et al., 2013).

Most research has concentrated on the effects of urban PM which contains high levels

Animals

Eight week old female BALB/c mice (Animal Resource Centre, Murdoch, WA, Australia) were housed in a pathogen-free environment with a 12 h:12 h light dark cycle, and provided with food and water ad libitum. All studies were approved by the Telethon Kids Institute Animal Ethics Committee and adhere to the guidelines of the National Health and Medical Research Council of Australia.

Sample collection

The top 2 cm of a 1 m2 area of surface soil was collected from four remote towns in arid environments across Western

Particle characterisation

All elements measured were detectable in all geogenic PM10 samples. Three elements dominated (Si, Fe and Al), with the remaining elements comprising < 0.1% of the metal content of the samples. Si was the most abundant element in all samples. Fe was the next abundant metal in Newman, Kalgoorlie and Tom Price, while Al was the second most abundant element in Karratha (Table 1). Endotoxin levels ranged from 93.2 to 614.1 EU/50 μL (equivalent to 0.5–15.8 ng/50 μL).

Body weight

Exposure to geogenic PM10 had no effect

Discussion

Exposure to geogenic PM has been linked to exacerbations of respiratory infections (Lin et al., 2005), including influenza (Xu et al., 2013). These studies have, however, been mostly restricted to cross-sectional epidemiological studies or anecdotal observations, and the specific effects of this prevalent environmental exposure have not yet been fully elucidated. The present study suggests for the first time that repeated exposure to geogenic PM, depending on the composition of the particles,

Conclusions

This study demonstrates long-standing implications for communities located in arid regions who are exposed chronically to geogenic PM10. These results build on our previous work showing the effects of acute exposure, and reflect more real-world chronic exposures. Our data suggests that geogenic PM10 is likely to exacerbate the response to respiratory viral infection and it therefore should be given more consideration as an environmental factor with significant impacts on community respiratory

Conflict of interest

The authors declare that they have no conflicts of interest.

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