The immunomodulatory and inflammatory effects of the inhalation of diesel particles in a murine model of healthy mice

Abstract

Introduction: Exposure to environmental pollutants such as diesel exhaust particles (DEP) increases the risk of respiratory diseases exacerbation. However, the effects that DEP can produce by itself in healthy people remain poorly understood. The present study aimed to assess the immunomodulatory and inflammatory effects of the inhalation of DEP in a murine model of healthy mice.

Material and methods: BALB/c ByJ mice were randomly divided into five experimental groups. Control group received 3 nasal instillations of saline during 8 days while the other four groups received nasal instillations of 150 µg of DEP 3 days per week during 8,17,26 and 53 days. Lung function assessment and flow citometry were performed.

Results: Inhalation of DEP decreased total monocytes (p<0.015 in all groups). Furthermore inflammatory monocytes were reduced after 26 days (p=0.001); however, resident monocytes increased as of 26 days (p=0.000). Eosinophils and neutrophils decreased at 26 (p=0.017 and p=0.041, repectively). Regarding dendritic cells (DC) the inhalation of DEP increased the total population at 26 and 53 days (p=0.017 and p=0.022, respectively). As regards macrophages, inhalation of DEP decreased total and alveolar populations (p<0.003 for all groups compared to control), while interstitial macrophages populations increased during the whole timeline (p=0.000 for all groups compared to control).

Conclusion: This mouse model provides evidence of the capacity of DEPs to increase DCs, interstitial macrophages and resident monocytes. Continuous exposure to DEP has an immunomodulatory and inflammatory effect.

Study funded by PI18/00344