Non-typeable Haemophilus influenzae decreases cilia beating via protein kinase C epsilon
1 VA Nebraska-Western Iowa Health Care System Research Service, Department of Veterans Affairs Medical Center, 4101 Woolworth Avenue, Omaha, NE, 68105, USA
2 Department of Environmental, Agricultural, and Occupational Health, College of Public Health, University of Nebraska Medical Center, Omaha, NE, 68198-5910, USA
3 Pulmonary, Critical Care, Sleep & Allergy Division, Department of Internal Medicine, 985300 Nebraska Medical Center, Omaha, NE, 68198-5300, USA
4 Department of Epidemiology, College of Public Health, University of Nebraska Medical Center, Omaha, NE, 68198-5910, USA
Respiratory Research 2012, 13:49 doi:10.1186/1465-9921-13-49Published: 19 June 2012
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.
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.
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.