CILIARY ACTIVITY OF BRONCHIAL EPITHELIUM UNDER EXPERIMENTAL COLD EXPOSURE IN VITRO

To date, the role of dysfunction of the bronchial ciliated epithelium (BCE) in the formation of mucociliary disorders during cold exposure has not been fully established. The aim of the study was to investigate the nature and severity of changes in the ciliary motility of the BCE under the influence of a cold stimulus in vitro. Ten volunteers with asthma underwent a bronchoscopy with biopsy of the lobar bronchus mucosa. The biopsy specimens were placed in a Hank’s balanced salt solution (HBSS) on a slide, located on the thermal stage, used to simulate the effect of various temperature on the BCE. Ciliary beat frequency (CBF, Hz) was recorded using a microscope, high-sensitivity digital camera and computer with specially developed software. The initial recording of CBF was performed at 24ºC, after which the temperature of HBSS was gradually increased to physiological level and repeated recording was made at the control points (28ºC and 36ºC). Then, the temperature of the solution was lowered and CBF was registered again at 28ºC, 21ºC and 17ºC. The initial CBF of the BCE varied from 6.74 to 3.77 Hz with average of 5.25±1.48 Hz (M±m). There was a statistically significant increase in CBF when the solution was heated: at 28ºC it was 6.33±1.36 Hz (p=0.004) and remained at this level up to 36ºC – 7.14±1.33 Hz (p=0.002). A gradual decrease in the solution temperature produced a reduction in CBF in comparison with the physiological conditions: 28ºC – 6.12±1.31 Hz (p=0.121), 21ºC – 5.27±1.32 Hz (p=0.001) and 17ºC – 3.95±1.18 Hz (p=0.0001). By the end of the experiment, CBF of the BCE decreased almost 2-fold in comparison with the physiological conditions. A mathematical model that characterizes the behavior of BCE cilia under cold stress was developed. Thus, the results of the study demonstrate a marked decrease in the motor activity of the BCE cilia under cold stress, which underlines a significant contribution of the functional disturbance of BCE to the pathophysiological mechanisms of hypersecretory disorders induced by inhalation of cold air.