Chlorhexidine effects on membrane lipid domains of human buccal epithelial cells

The effect of chlorhexidine gluconate on the adherence of Candida albicans to human buccal epithelial cells (BEC) and drug-induced alterations in BEC membrane-lipid packing order were examined. Treatment of BEC with attached yeasts with 0.1 and 0.2% chlorhexidine resulted in significant yeast detachment after 90 and 60 min, respectively. Following pre-treatment of BEC with greater than 0.1% chlorhexidine, yeast adherence was inhibited by greater than 80%. In parallel experiments, the fluorescence anisotropy of BEC labeled with fluorescent membrane probes--diphenylhexatriene (DPH) and trimethylammonium DPH--was assessed following exposure to chlorhexidine. The fluorescence anisotropy decreased with increasing concentrations of chlorhexidine, which indicated that the drug decreased epithelial-cell membrane-lipid packing order. Chlorhexidine concentrations that altered epithelial-cell membrane-lipid packing order, particularly in superficial regions, were similar to those drug concentrations required for detachment of adherent yeasts. Similar results were obtained with a second antifungal, nystatin A. While the effects of chlorhexidine on the buccal-cell membrane-lipid packing order were not reversed by multiple washings, the opposite situation occurred with nystatin A. The results suggest that chlorhexidine-induced alterations of BEC membrane-lipid order may be involved in the antifungal actions of the drug.