How does CFTR affect the lungs?
In the lungs, inactive or inefficient functioning CFTR results in impaired chloride transport and enhanced sodium absorption across airway epithelial cells (Boucher, 2007; Donaldson & Boucher, 2007). This leads to a net increase in water absorption (Boucher, 2007). The volume of the liquid that sits on the airway surface is reduced and the mucus in the airways becomes more viscid (sticky). In healthy lungs the cilia (small hairs on the surface of the airways) beat in a coordinated fashion so that they continually move mucus up and out of the lungs. This cleansing action of the cilia is impaired in CF because of the presence of very sticky mucus and dry airways (figures 2 & 3) which provide a favourable environment for bacterial infection. Structural changes in the CFTR protein have also been linked to defective phagocytosis (ingestion and destruction of bacteria by the white blood cells) of bacteria such as Pseudomonas aeruginosa and to reduced clearance of infection (Di et al, 2006; P
