Airway epithelial cell inflammatory signalling in cystic fibrosis

Abstract

Cystic fibrosis (CF) is the most common lethal monogenic disorder in Caucasians, estimated to affect one out of 2500–4000 new-borns. In patients with CF, lack of CF transmembrane conductance regulator (CFTR) Cl− channel function leads to progressive pulmonary damage and ultimately to death. Severe and persistent polymorphonuclear neutrophil-dominated endobronchial inflammation and chronic bacterial infection are characteristic hallmarks of CF lung disease. Whether CFTR dysfunction results directly in an increased predisposition to infection and whether inflammation arises independent of infection remains to be established. The loss of functional CFTR in airway epithelial cells promotes depletion and increased oxidation of the airway surface liquid. Activated neutrophils present in airways produce large amounts of proteases and reactive oxygen species (ROS). Together these changes are associated with diminished mucociliary clearance of bacteria, activation of epithelial cell signalling through multiple pathways, and subsequent hyperinflammatory responses in CF airways. The NF-κB pathway and Ca2+ mobilization in airway epithelial cells are believed to be of key importance for control of lung inflammation through regulated production of mediators such as interleukin-8 that participate in recruitment and activation of neutrophils, modulation of apoptosis, and control of epithelial barrier integrity. In this review, the current understanding of the molecular mechanisms by which airway epithelial cells contribute to abnormal lung inflammation in CF, as well as the anti-inflammatory strategies that can be proposed are discussed.