Paediatric respiratory reviews
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Defective expression and function of the cystic fibrosis transmembrane conductance regulator (CFTR) in cystic fibrosis (CF) airway epithelial cells are associated with airway mucus hypersecretion, inflammation and infection that begin early in life and lead, at an advanced stage of the disease, to severe airway obstruction with hyperviscous and adhesive airway mucus. Whether the abnormalities of airway mucus are already present at birth before infection is debatable. In CF, the impaired Cl(-) and HCO(3)(-) secretion associated with increased epithelial Na(+) absorption results in dehydration of airway mucus, decreased antimicrobial functions and impaired mucociliary clearance. ⋯ Alterations in mucin and lipid composition induce an increased viscosity and adhesiveness to the airways that can affect the mucociliary and cough transport. The increased content of pro-inflammation cytokines such as interleukin-8 (IL-8) suggest that, before infection, airway inflammation occurs very early in CF. The development of non-invasive techniques and humanised animal models (xenografts) represents a major opportunity to identify early abnormalities in CF airway mucus.