Exposure to hog barn dust alters airway epithelial ciliary beating

Swine confinement workers are at increased risk of airway diseases, including mucus membrane irritation syndrome, chronic rhinosinusitis and chronic bronchitis. Dust extracts from swine confinement facilities stimulate the production of pro-inflammatory cytokines in bronchial epithelial cells, including interleukin (IL)-8. As IL-8 is capable of blocking beta-agonist-stimulated increases in cilia beating, which impacts on mucociliary clearance, it was hypothesised that hog barn-dust exposure might alter cilia responses to stimulation. To test this hypothesis, ciliated bovine bronchial epithelial cell cultures were exposed to hog barn-dust extract (HDE) and ciliary beat frequency (CBF) was assayed. An elevation in baseline CBF was observed. This effect appeared to be independent of endotoxin but dependent upon nitric oxide. HDE also stimulated nitric oxide production in bronchial epithelial cells; however, stimulation of cilia beating by a beta-agonist did not occur in cells pre-exposed to HDE. These data demonstrate that hog barn dust can alter normal stimulation of cilia, suggesting a mechanism for the abrogation of stimulated increases in mucociliary clearance in response to inhaled dust exposure.