TNFα Affects Ciliary Beat Response to Increased Viscosity in Human Pediatric Airway Epithelium

In airway epithelium, mucociliary clearance (MCC) velocity depends on the ciliary beat frequency (CBF), and it is affected by mucus viscoelastic properties. Local inflammation induces secretion of cytokines (TNFα) that can alter mucus viscosity; however airway ciliated cells have an autoregulatory mechanism to prevent the collapse of CBF in response to increase in mucus viscosity, mechanism that is associated with an increment in intracellular Ca+2 level ([Ca2+]i). We studied the effect of TNFα on the autoregulatory mechanism that regulates CBF in response to increased viscosity using dextran solutions, in ciliated cells cultured from human pediatric epithelial adenoid tissue. Cultures were treated with TNFα, before and after the viscous load was changed. TNFα treatment produced a significantly larger decrease in CBF in cultures exposed to dextran. Furthermore, an increment in [Ca2+]i was observed, which was significantly larger after TNFα treatment. In conclusion, although TNFα has deleterious effects on ciliated cells in response to maintaining CBF after increasing viscous loading, it has a positive effect, since increasing [Ca2+]i may prevent the MCC collapse. These findings suggest that augmented levels of TNFα associated with an inflammatory response of the nasopharyngeal epithelium may have dual effects that contribute to maintaining the effectiveness of MCC in the upper airways.