Corresponding author Songmin Ying, MD, PhD, of Zhejiang University School of Medicine, and colleagues noted that asthma is a leading cause of pediatric emergency room (ED) visits and that childhood asthma rates have increased. One suspected reason for the increase is air pollution, which the authors say is linked to socioeconomic factors.
“Particulate matter is one of the major components of air pollutants, which mainly consists of coal combustion, car exhaust, construction site dust and smoke from combustion,” Ying and colleagues wrote.
Previous research has pointed to particulate matter as a worsening factor in asthma, and studies have also suggested that patients living in areas with high particulate matter are more likely to experience exacerbations from exposure to dust mites.
The authors wanted to better understand the relationship between particulate matter concentration and asthma, as well as the effects of short-term exposure to particulate matter on airway inflammation. They used data from 16,779,739 asthma visits from patients aged 0 to 14 years at the university hospital and evaluated those data against local particulate matter concentration data from the same area.
They found that the concentrations of PM2.5 and PM10 (named for the micrometer diameter of the particulate matter) showed a moderate positive correlation with emergency room visits and with the proportion of asthmatics among the total number of outpatient and emergency room visits, noting that other research has suggested that age may influence the effect of particulate matter, especially PM2.5. They therefore decided to divide their cohort into patients younger than 6 years and patients 6 years or older.
“The results confirmed that in children younger than 6 years of age, the correlation between PM concentration and asthma worsening was more pronounced than in older children,” they said.
The researchers expanded their study by developing a house dust mite-induced allergic airway inflammation model with mice exposed to particulate matter and a house dust mite challenge. This study showed that particulate matter-induced airway inflammation was exacerbated by house dust mites, but also that IL-33 neutralizing antibody could play a protective role against such inflammation.
“We confirmed that IL-33 neutralizing antibody could alleviate the exacerbated airway inflammation caused by PM exposure in asthmatic mice,” they wrote.
Still, Ying and colleagues cautioned that the effect was protective, meaning its value came when it preceded the allergy challenge. IL-33 antibody did not provide significant relief from airway inflammation in mice after the dust mite-induced inflammation had already occurred, “which could be because the airway inflammation caused by [house dust mites] was essentially formed when the IL-33 antibody was administered.”
The researchers said their study provides important new insights into possible ways to prevent asthma exacerbations in children or to protect children already affected by high concentrations of particulate matter.
Yang X, Zhang Y, Zhan X, et al. Exposure to particulate matter is strongly correlated with exacerbation of childhood asthma. Aging (Albany NY). Published online July 13, 2021. doi:10.18632/aging.203281