The airway epithelium works as a physical barrier between the external environment and
internal structures, which represent the lung's first defense against inhaled microorganisms.
The barrier function of airway epithelium is accomplished by (1) mucociliary transport, which
traps and removes inhaled foreign particles in the airways 1;(2) secreted antimicrobial
molecules that kill inhaled pathogens 2; and (3) cell-cell connections that regulate epithelial
paracellular permeability. 3 The integrity of the airway epithelium in individuals with cystic …