Abstract
BACKGROUND: Haemophilus influenzae infection of the nasal epithelium has long been associated with observations of decreased nasal ciliary beat frequency (CBF) and injury to the ciliated epithelium. Previously, we have reported that several agents that slow CBF also have the effect of activating protein kinase C epsilon (PKCε) activity in bronchial epithelial cells. The subsequent auto-downregulation of PKCε or the direct inhibition of PKCε leads to the specific detachment of the ciliated cells. METHODS: Primary cultures of ciliated bovine bronchial epithelial cells were exposed to filtered conditioned media supernatants from non-typeable H. influenzae (NTHi) cultures. CBF and motile points were measured and PKCε activity assayed. RESULTS: NTHi supernatant exposure significantly and rapidly decreased CBF in a dose-dependent manner within 10 minutes of exposure. After 3 hours of exposure, the number of motile ciliated cells significantly decreased. Direct measurement of PKCε activity revealed a dose-dependent activation of PKCε in response to NTHi supernatant exposure. Both CBF and PKCε activity changes were only observed in fresh NTHi culture supernatant and not observed in exposures to heat-inactivated or frozen supernatants. CONCLUSIONS: Our results suggest that CBF slowing observed in response to NTHi is consistent with the stimulated activation of PKCε. Ciliated cell detachment is associated with PKCε autodownregulation.