Co-Exposure to Cigarette Smoke and Alcohol Decreases Airway Epithelial Cell Cilia Beating in a Protein Kinase Cε-Dependent Manner

Abstract

Alcohol use disorders are associated with increased lung infections and exacerbations of chronic lung diseases. Whereas the effects of cigarette smoke are well recognized, the interplay of smoke and alcohol in modulating lung diseases is not clear. Because innate lung defense is mechanically maintained by airway cilia action and protein kinase C (PKC)-activating agents slow ciliary beat frequency (CBF), we hypothesized that the combination of smoke and alcohol would decrease CBF in a PKC-dependent manner. Primary ciliated bronchial epithelial cells were exposed to 5% cigarette smoke extract plus100 mmol/L ethanol for up to 24 hours and assayed for CBF and PKCε. Smoke and alcohol co-exposure activated PKCε by 1 hour and decreased both CBF and total number of beating cilia by 6 hours. A specific activator of PKCε, DCP-LA, slowed CBF after maximal PKCε activation. Interestingly, activation of PKCε by smoke and alcohol was only observed in ciliated cells, not basal bronchial epithelium. In precision-cut mouse lung slices treated with smoke and alcohol, PKCε activation preceded CBF slowing. Correspondingly, increased PKCε activity and cilia slowing were only observed in mice co-exposed to smoke and alcohol, regardless of the sequence of the combination exposure. No decreases in CBF were observed in PKCε knockout mice co-exposed to smoke and alcohol. These data identify PKCε as a key regulator of cilia slowing in response to combined smoke and alcohol-induced lung injury.