Antimicrobial peptides in the real world: implications for cystic fibrosis.

T he continuous cycle of respiratory infections and lung inflammation is a hallmark of cystic fibrosis (CF) lung disease and plays a central role in respiratory failure that develops in end-stage disease. Effective mucociliary clearance is an essential mechanism in host defence against infection and requires a functional ‘‘two-layer’’ mucus clearance system composed of a periciliary liquid layer and an overlying mucus layer in which inhaled substances are trapped [1]. Together these two separate layers constitute airway surface liquid (ASL). Adequate hydration is essential for an optimal function of the mucociliary clearance system. Dehydration of the mucosal surface in CF may not only hamper effective mucus clearance but also causes adhesion of mucus to the epithelial surface. This results in airway flow obstruction, inflammation and favouring infections.