Correlation of bronchial inflammation pattern and airway response to cold stimulus in patients with uncontrolled asthma

Background: Features of bronchial inflammation that contribute to the development of cold airway hyperresponsiveness in patients with asthma have been poorly studied. We aimed to investigate the correlation between the neutrophils and airway response to cold stimulus. Methods: In 116 patients with uncontrolled asthma (mean age 43.2±0.8 years), the lung function (FEV1,%), airway response to 3-minute isocapnic hyperventilation with cold air (IHCA), the cell composition of induced sputum (IS, %), the activity of myeloperoxidase (MPO, in pixels), and the degree of structural integrity of cells using the destruction index (DI, relative units) were studied. Asthma control was assessed by ACT questionnaire. Results: The patients were divided into 2 groups based on the number of neutrophils in IS: group 1 (n=52) less than 40%, and group 2 (n=64) more than 40%. The number of eosinophils in IS was 21.2±1.4 vs. 14.3±1.4%, respectively (p=0.001). The baseline FEV1 was 87.3±1.7 and 84.3±2.6% (p>0.05); the FEV1 drop in response to IHCA was -10.9±1.3 and -10.9±1.6%. The level of ACT in group 1 was higher (13.7±0.33 vs. 12.4±0.44 points, p=0.026), the MPO content of granulocytes was lower (81.7±3.6 vs. 135.9±12.1 pixels, p=0.00001), as well as neutrophil DI (0.47±0.02 vs. 0.56±0.04, p=0.047) and DI of the bronchial epithelium (0.52±0.02 vs. 0.63±0.06, p=0.05). The correlation was found between the content of neutrophils in IS and the airway response to IHCA (r=-0.18, p=0.047). Conclusion: An increase in the number of neutrophils with an escalation of their functional activity in patients with uncontrolled asthma is related to the severity of the airway response to the IHCA.