The effect of fine suspended particles in the atmospheric air on the formation and course of the T2 endotype of bronchial asthma: a case-control study

Abstract

The aim of the study was to investigate the effect of fine suspended particles in the atmospheric air on the formation and course of allergic and non-allergic phenotypes of the T2 endotype of bronchial asthma (BA) using the case-control study. Materials and methods. BA patients were selected in the course of seeking medical help. The groups were formed on the base of matching criteria (gender, age, body mass index, level of education), supplemented by the collection of information about potential cofounders. Based on the data on monitoring the content of fine suspended particles in the atmospheric air of Kazan, the average annual and maximum concentrations of PM2.5 and PM10 fractions were determined in the residential areas. The group of “cases” included forty patients with an allergic phenotype and 42 patients with an eosinophilic non-allergic phenotype of bronchial asthma, the control group included forty eight people. Additionally, sampling of atmospheric air was carried out using an 8-stage impactor to assess the content of bacterial endotoxin, and elemental composition. Results. Higher levels of pollution with fine suspended particles were demonstrated in the areas of residence of BA patients, comparing to the control group. An increase in the average annual concentration of the PM2.5 by 10 µg/m3 increases the odds of the eosinophilic non-allergic BA phenotype in adults by 4.76 times. The odds of the allergic phenotype of bronchial asthma increases in the presence of bacterial endotoxin - 1.32 times per 0.01 EU/m3 of endotoxin in the 3.2-18 µm size fraction. A more severe course of the eosinophilic non-allergic BA phenotype was noted at higher average annual concentrations of the PM2.5. The control of allergic asthma depends on the bacterial contamination of the aerosol. Limitations of the study are related to the use of geospatial approach to assess personalized average annual and maximum annual concentrations. Conclusion. The role of fine suspended particles in the atmospheric air in the development of bronchial asthma in adults has been shown. Various mechanisms were established to be involved in the formation of the clinical picture of the eosinophilic non-allergic and allergic phenotypes of bronchial asthma.