**2. Material and methods**

The research aim was to study the effect of fine particles in the ambient air on the formation, course, and underlying mechanisms of atopic allergic and eosinophilic non-allergic phenotypes of the T2-endotype of bronchial asthma in adults (18–65 years old).

The study included the following parts: (1) a case-control study, (2) a biomarker study as a part of the case-control study, (3) an epidemiological study of ecological type based on geoinformatics approach with a retrospective analysis of data on environmental pollution and population health.

For the case-control study, patients with bronchial asthma were selected while seeking medical help ("cases"), and the comparison group was selected from among those who did not suffer from bronchial asthma ("controls"). The groups were formed based on inclusion/exclusion criteria and comparison criteria, supplemented by the collection of information about potential confounders. The probable T2-endotype of bronchial asthma was determined by the absolute number of eosinophils in the blood (≥150 cells/μl). A total of 156 patients with bronchial asthma were examined, of which 82 patients were selected in the "cases" group (40 patients with an allergic phenotype, 42 patients with an eosinophilic non-allergic phenotype of bronchial asthma). The inclusion criteria for the "cases" group were: (1) age from 18 to 65 years; (2) an established clinical diagnosis of an allergic or non-allergic phenotype of the T2-endotype of bronchial asthma; (3) informed consent to participate in the study. The exclusion criterion for the group of "cases" was the allergen-specific immunotherapy or biological therapy at the time of examination, or information in the medical records about the use of such therapy earlier. The comparison group (48 people) was selected according to the following comparison criteria: (1) compliance of the distribution of "controls" with the distribution of "cases" by sex, age (in the range up to 10 years), body mass index (up to 23.9; 24–29.9; 30 and more kg/m2 ), level of education (secondary; college; high); (2) exclusion of the diagnosis of bronchial asthma and other chronic respiratory diseases; (3) informed consent to participate in the study. For individuals included in the study, the average and maximal annual concentrations of PM2.5 and PM10 fractions averaged over the period 2014–2020 were determined, considering measurements at monitoring points closest to the areas of residence. For measurements, the DustTrak™ II Aerosol Monitor 8530 (TSI Inc., USA) was used. Additionally, in the areas of residence, ambient air sampling was carried out by the 8-stage impactor MOUDI 100NR (TSI, USA) to study the elemental composition of the aerosol (SEM, energy dispersive spectroscopy) and the contamination by bacterial endotoxin (kinetic LAL test). Besides, air samples were taken for microbiological examination by classical cultural methods and using MALDI-TOF spectrometry. Using the multiple logistic regression, adjusted odds ratios were calculated with 95% confidence intervals for allergic and eosinophilic non-allergic phenotypes of bronchial asthma in comparison with the comparison group, depending on the levels of exposure variables characterizing air pollution with particulate matter.

For the biomarker study, as a part of the case-control study, 61 patients with T2-endotype of BA were examined (34 patients with an allergic phenotype, 27 patients with a non-allergic phenotype of the disease). The comparison group consisted of 30 people without symptoms of asthma and other allergic diseases who were matched by gender, age, body mass index (BMI), profession (position). All patients with BA and persons from the comparison group underwent blood sampling to determine biological markers of various types of inflammation: alarmins (TSLP, IL-33, IL-25), T2-cytokines (IL-4, IL-5, IL-13), DPP4, and also—in order to clarify the involvement of non-T2-mechanisms—IL-6, TGF-beta1, IL-17A, IL-1beta; multiplex analysis using xMAP Luminex technology was applied. The blood serum level of periostin was determined by ELISA. The study design was supplemented by whole blood sampling from the same study participants and subsequent analysis of the expression of genes encoding certain cytokines: IL-4, IL-5, IL-6, TGF-beta1, IL-17A, IL-1beta, IL-25, IL-33. In the biomarker study, the calculated masses of aerosol particles deposited in different parts of the lungs were used as additional exposure characteristics. To estimate the masses of aerosol particles deposited in the lungs, an original method to reconstruct the aerosol particle size distribution function using actual PM2.5 and

#### *Fine Particles in the Ambient Air as a Risk Factor of Bronchial Asthma in Adults DOI: http://dx.doi.org/10.5772/intechopen.112419*

PM10 concentrations under the assumption of a lognormal distribution characteristic of atmospheric aerosols was developed. To assess the relationship between serum levels of cytokines and concentrations of PM2.5 and PM10 fractions, multiple linear regression was used, gender, age, body mass index (BMI) being included as confounders in the regression models. In addition, a data aggregation method based on the principal component analysis was applied.

To study the relationship between ambient air pollution with particulate matter and bronchial asthma in adults (18–65 years old), a retrospective analysis of the incidence of bronchial asthma (ICD-10 codes J45.0, J45.1, J45.8) for 2014–2020 was carried out. BA incidence was determined for the population of Kazan in and for persons living in the areas at up to 1 km from the monitoring points as well. The database of social and hygienic monitoring and the regional medical information system "Electronic Health of the Republic of Tatarstan" were used. The absolute risks of bronchial asthma in adults (18–65 years old), as well as the absolute risks of BA phenotypes, were calculated. Using linear mixed models based on the Poisson or the negative binomial distribution, the dependences of the absolute risks of BA phenotypes on the PM fraction concentrations were studied.

### **3. Results and discussions**
