Role of peroxidases in the formation of an osmo-dependent reaction of airways in patients with asthma

<b>Background:</b> The involvement of cellular and extracellular peroxidases (PO) in the formation of osmo-dependent airway responsiveness in asthma is little known. We aimed to assess the dynamics of peroxidases in response to a hyposmolar stimulus in patients with asthma. <b>Methods:</b> In 62 patients with mild-to-moderate persistent asthma, the level of control was assessed using the Asthma Control Test (ACT, points). Lung function (FEV1), and airway response (ΔFEV1, %) to 3-min. inhalation of ultrasonically nebulized distilled water (UNDW) were measured by spirometry. The reaction products for PO in the granulocytes of induced sputum were determined by optical density calculating the average cytochemical coefficient (in pixels). The PO concentration (ng/mL) in the blood serum was determined by immunoassay. <b>Results:</b> The patients were divided into two groups according to the level of ACT: group 1 included 32 patients with ACT less than 20 points (14.4±0.57 points), group 2 – 30 patients with ACT more than 20 points (22.1±0.33 points). The groups did not differ in the age of patients, FEV1, ΔFEV1. The concentration of PO in sputum was 134.2±12.2 vs. 102.6±10.1 pixels (p=0.054). The concentration of blood PO after the UNDW test in both groups decreased, to a greater extent in group 1 from 145 (67.0; 329.0) to 47.5 (32.1; 177.0) ng/mL (p=0.013). In group 1, a correlation was found between the baseline blood PO and ACT (Rs=-0.40; p=0.045), in group 2 – between PO in induced sputum and ΔFEV1 (-0.52; p=0.023). <b>Conclusion:</b> The decrease of PO after exposure to a hyposmolar stimulus&nbsp;suggest increased enzyme&nbsp;utilization in the reactions of oxidative and halogenated stress in the respiratory tract.