Cold air alters MUC5AC and MUC5B expression in the airways of asthma patients

Background: Cold airway hyperresponsiveness (CAH) is common in asthma. However, it is not clear, if any changes in the expression of particular mucins are induced by cold air inhalation in vivo. Objectives: The aim of the study was to investigate MUC5AC and MUC5B expression in nasal epithelium of asthma patients under cold temperature. Methods: The study enrolled 33 patients with mild-to-moderate asthma and mean age 37.9±1.89. Isocapnic (5% CO2) cold air (-20°C) hyperventilation was performed through the nose and the mouth during 3-min. Nasal epithelium was obtained by superficial scrape biopsy before and after the hyperventilation. Expression of mucins was evaluated by qRT-PCR and 2-ΔΔCT method. Results: Basal expression of MUC5AC in nasal epithelium was 3-times higher in patients with CAH when compared to patients without the hyperresponsiveness. After the cold air hyperventilation MUC5AC expression in CAH patients remained increased up to 2.3-fold. Generally, cold air produced 1.6-fold increase in MUC5AC expression with slightly higher response in patients without CAH (1.7-fold) and lower – in patients with CAH (1.4-fold). At the same time, CAH was associated with down-regulation of MUC5B before (0.8-fold) and after (0.05-fold) the challenge. Interestingly, cold air inhalation resulted in decrease of MUC5B expression (0.2-fold) in patients with CAH, while in patients without CAH it increased (3.4-fold). Conclusions: The obtained results suggest that cold air may produce differential response in terms of mucins expression. Cold airway hyperresponsiveness is associated with increased MUC5AC and decreased MUC5B expression, what is typical for asthma. This study was supported by RFBR (project 17-54-53162).