Effects of α-toxin of Staphylococcus aureus on the ciliary activity and ultrastructure of human nasal ciliated epithelial cells

Abstract

Objective: The in vitro effects of staphylococcal α-toxin on ciliary activity were investigated at different concentrations and exposure times. Study Design: Ciliated epithelial cells of the sphenoid sinus were taken from patients operated on for pituitary tumors. Video-computerized analysis technique and transmission electron microscopy were used to analyze the effects of the toxin on ciliary activity. Methods: Ciliary beat frequency (CBF) was measured in four different concentrations of α-toxin including 0.1, 1, 10, and 50 μg/mL. CBF was measured at 2, 4, 6, 12, 24, and 48 hours after administration of the toxin. To observe reversibility of the reduced ciliary activity, after 24-hour incubation in the media containing 10 μg/mL of α-toxin, the media were replaced with α-toxin-free media. The tissues were also processed for transmission electron microscopy to observe ultrastructural changes of the epithelial cells. Results: CBF increased significantly at 2-hour incubation and then decreased significantly after 12- hour incubation in 10 μg/mL of α-toxin (P< .05, repeated-measures ANOVA). The transmission electron microscopic findings showed mitochondrial swelling and a slight protrusion of the plasma membrane of the cilia. In toxin-free media, loss of ciliary activity was not recovered. Conclusions: CBF increased at first, but with increasing incubation time ciliary movements decreased gradually and stopped eventually. This loss of CBF may be an irreversible change associated with ultrastructural changes in the mitochondria and the plasma membrane of the cilia.