PROFILE OF BRONCHIAL INFLAMMATION AND CLINICAL FEATURES OF MILD BRONCHIAL ASTHMA

Abstract

Heterogeneity of respiratory tract inflammation determines the clinical course and control of mild asthma. The aim of the research was to study the relationship between clinical and functional parameters and the form of bronchial inflammation in patients with mild persistent asthma against the background of standard basic anti-inflammatory therapy. In 198 patients with mild asthma (the mean age was 41.5±0.7 years old) against the background of maintenance therapy with low doses of inhaled glucocorticosteroids (ICS at a dose ≤500 mcg/day by beclomethasone dipropionate), there were determined the level of asthma control according to the questionnaire Asthma Control Test (ACT), lung function, airway reaction to 3-minute isocapnic hyperventilation with cold (-20ºC) air; there was done the collection of induced sputum (IS). The content of cells in cytograms of IS was assessed. The activity of myeloperoxidase (MPO) (in pixels) was measured by cytochemical method in neutrophilic and eosinophilic granulocytes. Group 1 (n=43; 22%) included patients with the eosinophilic pattern of bronchial inflammation, group 2 (n=155; 78%) included patients with mixed pattern of inflammation. In group 2, unlike the patients of group 1, in the inflammatory profile of infiltrate against the background of high neutrophil content (34.6±1.1 and 10.8±0.5%, respectively; p=0.000001), there was found an increased level of eosinophils (17.0±1.1 vs. 21.2±1.8%, respectively; p=0.048), and there was revealed a higher intragranular deposition of MPO (85.8±3.5 vs. 77.0±3.2 pixels, respectively; p=0.057). The mixed type of inflammation with the dominant neutrophil component and the greatest activity of MPO was associated with more pronounced clinical symptoms of the disease and low level of asthma control (16.0±0.7 vs. 18.7±0.4 ACT points, respectively; p=0.004), lung function decrease (FEV1 was 89.4±1.4 vs. 97.9±2.2%, respectively; p=0.005) and degree of FEV1 drop in response to bronchial provocation by cold air (-10.1±1.1 vs. -3.4±1.1%, respectively; p=0.002), due to insufficient anti-inflammatory effect of the used controller therapy. A discriminant equation is proposed, which can serve as an additional criterion for the effectiveness of anti-inflammatory therapy.