Effects of free radicals on ciliary movement in the human nasal epithelial cells

Objective: There have been few reports on the effects of free oxygen radicals on ciliary mobility of nasal respiratory epithelial cells. The aim of this study was to determine the effects of free radicals and antioxidants on human nasal epithelial cells (HNECs) using video-computerized analysis. Methods: Human nasal epithelial cells were obtained from the nasal cavity of normal volunteers. Ciliary beat frequency (CBF) was calculated as the mean value of ten randomly selected cells. The proportion of the area with normal CBF (above 8 Hz) was calculated from 10 randomly selected sites per specimen. Free radicals were produced by xanthine–xanthine oxidase enzymatic system. The generation of free radicals was confirmed by chemoilluminometer. CBF and the proportion of the area with normal CBF were measured at every 5 min for 30 min after the addition of enzyme. For the evaluation of the antioxidant effects on free radical-mediated ciliary slowing in HNECs, cells were incubated in superoxide dismutase solution (300 unit/ml) for 30 min and 3-aminobenzamide (5 mM). Results: Superoxide produced by 0.4 mM xanthine and 400 miliunit/ml xanthine oxidase decreased CBF (7.71±1.91 Hz). A total of 2 min later, ciliary slowing was evident (3.87±1.10 Hz). Regarding the changes in proportion of epithelial area that showed normal CBF experimental group showed a significant decrease in percentage of epithelial area with normal CBF over time. Superoxide dismutase prevented ciliary slowing (8.76±0.99 Hz). Moreover, 3-aminobenzamide, an inhibitor of the DNA repair enzyme poly-ADP ribose polymerase, prevented inhibition of CBF (8.32±0.61 Hz). Conclusions: These results suggest that oxygen-mediated damage to DNA may be the mechanism of the deterioration effects of oxygen radicals on the ciliated respiratory nasal epithelium.