The role of fine suspended particles of atmospheric air in the formation of eosinophilic inflammation in T2-endotype of asthma

Abstract

BACKGROUND: Allergens induce eosinophilic inflammation in the T2 endotype of asthma. However, much less is known about the role of non-specific factors (suspended particles in the atmospheric air-PM).
 AIMS: To define eosinophilic inflammation on the basis of several biomarkers in the T2 endotype of asthma exposed to PM.
 MATERIALS AND METHODS: We studied 150 patients with asthma, and 61 patients with T2 endotype of asthma (ages 1865 years) were enrolled. Group 1 included 34 patients with allergic asthma, and group 2 included 27 patients with non-allergic asthma. Moreover, 30 healthy matched controls without asthma and other allergic diseases were enrolled in the study. Clinical examination and allergy testing were performed. Additionally, serum levels of IL-33, IL-25, IL-4, IL-5, IL-13, DPP4 (multiplex assay), and periostin (ELISA) were evaluated. The analyses of the average annual concentrations (Avr) and the maximal annual concentrations (MaxAvr) of PM2.5 and PM10 in Kazan were conducted using the database of the Center for Hygiene and Epidemiology in the Republic of Tatarstan, being averaged over the period from 2014 to 2020 years in monitoring points at residential areas. Statistical analyses were performed using R version 4.0.5. The study was funded by RFBR (Project no. 19-05-50094).
 RESULTS: We detected increased blood eosinophil count and IL-5 levels in patients with asthma. High levels of total IgE (p=0.0001) that correlated with IL-4 levels were observed only in patients with allergic asthma (rS=0.38; p=0.045). Moreover, elevated IL-25 levels were found in patients with allergic asthma (p=0.009). No significant differences in IL-13 levels in patient with asthma were found. The regression analysis revealed that the PM2.5Avr increase by 1 mcg/m3 increases IL-33 and IL-25 levels, but the PM10Avr increase raises the IL-25 levels only in patients with non-allergic asthma. No significant increase in IL-25 and IL-33 levels under exposure to PM2.5Avr and PM 10Avr was detected in patients with allergic asthma.
 CONCLUSIONS: The results of this study indicate the pivotal role of fine suspended particles in the development and maintenance of eosinophilic inflammation in patients with non-allergic asthma.