New research from Cincinnati Children’s sheds light on why exposure to diesel exhaust particles from traffic pollution leads to increased asthma severity in children. The particles increase blood levels of IL-17A, a protein associated with several chronic inflammatory diseases.

The study, published online in the Journal of Allergy and Clinical Immunology, also shows that neutralizing IL-17A prevented airway inflammation in mice and humans.

Neutralization of IL-17A “may be a useful potential therapeutic strategy to counteract the asthma-promoting effects of traffic-related air pollution, especially in highly exposed, severe allergic asthmatics,” says Gurjit Khurana Hershey, MD, PhD, director of asthma research at Cincinnati Children’s and senior author of the study.

Hershey and colleagues studied 235 children and teens with asthma.  The researchers plotted each person’s primary address and estimated their diesel exposure based on where they lived.  The researchers also studied mice exposed to diesel particles and dust mites, a common household allergen.

In children with asthma, diesel exposure was associated with more frequent asthma symptoms and increased IL-17A blood levels.  Similarly, exposure to both diesel and dust mites resulted in more severe asthma in mice compared to dust mite exposure alone.  When IL-17A was neutralized in mice, it alleviated airway inflammation induced by diesel exposure.