Role of diesel exhaust particles in the induction of allergic asthma to low doses of soybean

• Published in: Environmental research Vol. 196; p. 110337
• Main Authors: de Homdedeu, M., Cruz, M.J., Sánchez-Díez, S., Gómez-Ollés, S., Ojanguren, I., Ma, D., Muñoz, X.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01-05-2021
• Subjects: Air Pollutants - toxicity; Air pollution; Allergens; Animals; Asthma - chemically induced; Dendritic cells; Glycine max; Hydrogen Peroxide; Mice; Mice, Inbred BALB C; Oxidative stress; Particle deposition; Specific-IgE; Vehicle Emissions - toxicity; Particle deposition; Oxidative stress; Air pollution; Dendritic cells; Specific-IgE
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2020.110337

Exposure to environmental pollutants such as diesel exhaust particles (DEP) increases the risk of asthma and asthma exacerbation. However, the exact mechanisms inducing asthma to low doses of allergens remain poorly understood. The present study aimed to analyse the immunomodulatory effect of the inhalation of DEP in a mouse model exposed to non-asthmagenic doses of soybean hull extract (SHE).
BALB/c ByJ mice were randomly divided into four experimental groups. Two groups received nasal instillations of saline and the other two groups received 3 mg ml−1 SHE during 5 days per week for 3 weeks. One group in each pair also received 150 μg of DEP in the same instillations 3 days per week. SHE-specific IgE levels, oxidative stress, leukocyte pattern and optical projection tomography (OPT) imaging studies were assessed.
Inhalation of SHE and/or DEP increased levels of H2O2 in BAL, while coexposure to SHE and DEP increased SHE-specific IgE levels in serum. Inhalation of SHE alone increased eosinophils, B cells, total and resident monocytes and decreased levels of NK cells, while inhalation of DEP increased neutrophils and decreased total monocytes. Regarding dendritic cells (DC), the inhalation of SHE and/or DEP increased the total population, while the inhalation of SHE alone increased Th2-related DCs (CD11b + Ly6C-) and decreased tolerogenic DCs (CD11b-Ly6C-). However, coexposure to SHE and DEP increased oxidative stress-sensitive DCs (CD11b-Ly6C+) and decreased Th1-related DCs (CD11b + Ly6C+). As regards macrophages, inhalation of SHE and DEP decreased total and alveolar populations. DEP deposition in lung tissue did not differ between groups.
Coexposure to DEP activates the asthmatic response to low doses of soy by triggering the immune response and oxidative stress.
•Diesel exhaust particles coexposure induces asthma to soybean when the dose is too low to generate a response by itself.•It does so by increasing SHE-specific IgE and H2O2 levels and by altering lung leukocyte homeostasis.•Visualizing DEP deposition, the study determined that these particles reached the more distal airways to the same extent in both groups.