Background  Cilia plays an important role in airway defense mechanisms. However, due to limitations in the research techniques and tools for observation, in vivo animal studies on the effects of intranasal corticosteroids on ciliary motion are scarce.

  Objective  To observe and investigate the effects of intranasal corticosteroids on nasal ciliary motion in vivo and in vitro using a new method.

  Methods  Sixty rats were randomly divided into in vivo observation group and in vitro observation group. Each group was randomly divided into three subgroups: budesonide group, mometasone furoate and fluticasone propionate, and phosphate buffered saline (PBS) was used as the control for the three subgroups. Rats in the in vivo observation group were anesthetized and their nasal septal mucosae were surgically exposed immediately; while rats in the in vitro observation group were over-anesthetized, severed and executed, and their nasal septal mucosae were taken and placed in the culture medium. The ciliary motion on the nasal mucosal surface was observed under the new digital microscope system. The differences in ciliary beat frequency (CBF) between the two groups were compared before and after drug addition to the nasal mucosal surface of rats within 60 min.

  Results  The CBF of nasal mucosa of the rats in the in vivo observation group was significantly higher than that in the in vitro observation group (9.83 ± 0.94 Hz vs 6.10 ± 0.91 Hz, P<0.001). Under in vivo condition, budesonide, mometasone furoate, and fluticasone propionate had no significant effect on CBF in rats' nasal mucosa within 60 min. Under in vitro condition, budesonide caused an immediate decrease in CBF, with statistically significant differences in CBF between the two groups at all time points within 60 min (P<0.05); mometasone furoate decreased CBF continuously, and the differences in CBF between the two groups at each time point after 5 min of addition were statistically significant (P<0.05); fluticasone propionate caused a fluctuating decrease in CBF, and the differences in CBF between two groups at all time points from 0 to 5 min and from 20 to 60 min were statistically significant (P<0.05).

  Conclusion  Budesonide, mometasone furoate, and fluticasone propionate have no significant effect on ciliary motion in vivo, while they all produce varying degrees of inhibition of ciliary motion in vitro, indicating that intranasal corticosteroids have no significant ciliary toxicity, with good safety. Meanwhile, the in vivo evaluation system used in this study compensates for the great difference between in vitro observation and the real physiological environment, which can be used to objectively evaluate the safety and ciliary toxicity of nasal drugs.