Exposure to Pseudomonas aeruginosa and purified LPS alter CFTR-dependent ion conductance in cultured 2WT2 epithelial cells in a time and dose dependent fashion.

摘要

The most common heritable genetic disease in America, cystic fibrosis (CF), is caused by mutations in the CF transmembrane conductance regulator (CFTR), a chloride channel that interacts with and regulates a number of other proteins. Pseudomonas aeruginosa infects 80% of patients. It is not known how mutations in the chloride channel allow for colonization of the majority of patients by a single pathogen. The hypothesis that CFTR interacts with toll-like receptor 4 (TLR4) to phagocytise bacteria was tested. A competitive antagonist of TLR4 did not alter the rate of phagocytosis of P. aeruginosa by cultured epithelia; however, bacteria formed antibiotic resistant microcolonies in these experiments meaning the actual rate of phagocytosis was not measured. Cultured epithelia treated with P. aeruginosa had increased CFTR channel activity. Lipopolysaccharide (LPS) purified from P. aeruginosa also increased CFTR channel activity in a dose dependent manner; however, shorter exposure to LPS resulted in reduced CFTR channel activity. This data is consistent with a model in which CFTR is removed from the plasma membrane during phagocytosis of P. aeruginosa followed by recruitment of the channel to the membrane to replace channels removed during phagocytosis. More studies are needed to confirm this model, but this is the first report of a bacterial product causing a biphasic time-dependent and a dose-dependent alteration of CFTR channel activity.