Non-typeable Haemophilus influenzae decreases cilia beating via protein kinase C epsilon

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 (PKC epsilon) activity in bronchial epithelial cells. The subsequent auto-downregulation of PKC epsilon or the direct inhibition of PKC epsilon 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 PKC epsilon 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 PKC epsilon activity revealed a dose-dependent activation of PKC epsilon in response to NTHi supernatant exposure. Both CBF and PKC epsilon 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 PKC epsilon. Ciliated cell detachment is associated with PKC epsilon autodownregulation.