Dietary polyphenols affect MUC5AC expression and ciliary movement in respiratory cells and nasal mucosa

Abstract

BACKGROUND: Dietary polyphenols have been widely consumed in food, and their anti-inflammatory and anticancer activities have been recently studied. Although the effects of dietary polyphenols on mucin hypersecretion have been studied to some extent, the effects of mucociliary movement have not been elucidated thus far. Therefore, we investigated whether dietary polyphenols inhibit MUC5AC gene expression in NCI-H292 cells, and, if so, whether they would have an effect on ciliary beat frequency (CBF) of human nasal mucosa.

METHODS: NCI-H292 cells were pretreated with four different dietary polyphenols ([6]-gingerol, epigallocatechin gallate (EGCG), curcumin, and quercetin) and were treated with IL-1beta (10 ng/mL). Proliferation of NCI-H292 cells was analyzed. The mRNA expression of MUC5AC was determined by real-time polymerase chain reaction. CBF of normal nasal mucosa, which was obtained from the ethmoid sinus and treated with the polyphenols, was assessed via inverted microscope and computerized program.

RESULTS: Minimal inhibitory concentration (MIC) of MUC5AC expression of each polyphenol was found as follows: [6]-gingerol, 1 microM; EGCG, 20 microM; quercetin, 40 microM; and curcumin, 10 microM. No polyphenol influenced cell proliferation at this MIC. CBF was not affected by [6]-gingerol, quercetin, or EGCG, but ciliary movement decreased in curcumin.

CONCLUSION: [6]-Gingerol, quercetin, and EGCG may be considered as antihypersecretory agents because they effectively inhibit mucus secretion of respiratory epithelial cells while maintaining normal nasal ciliary movement.