Patients with cystic fibrosis (CF) have a lesion in a gene which encodes a cAMP-regulated chloride channel, CFTR. This error is associated with abnormal regulation of other ion channels, abnormal glycosylation of secreted and cell surface molecules, and vulnerability to bacterial infection and inflammation in the lung. Lung infection and inflammation relentlessly progress to take the patients' lives. The exact mechanism(s) by which mutation in CFTR leads to lung infection and inflammation is not established, though this is critical in devising therapeutic strategies directed at the basic defect. Several hypotheses, not normally exclusive, which invoke different mechanisms, have been advanced to explain the connection. Studies using our human airway epithelial cell lines transfected with the R domain of CFTR and with mutant forms of CFTR support the hypothesis that the commonest infecting bacteria in CF, Pseudomonas aeruginosa, adhere to a greater extent to airway epithelial cells without functional CFTR than they do to normal cells because CF phenotype cells have increased surface asialo GM1, a receptor for Pseudomonas pili. Adherence of pili stimulates release of IL-8, a chemoattractant. However, we also found that the inflammatory response to pseudomonas delivered to the lung encased in agar beads (bypassing adherence and defensin killing) is excessive and lethal in CF mice. Thus, there must be a mechanism by which the CF host response becomes exaggerate din addition to a defect which allows a pristine CF lung to retain bacteria. In this proposal, we will investigate the inflammatory response of CF and non-CF mice, to pseudomonas encased in agar beads, including the contribution of CF genotype, pseudomonas adherence, and specific inflammatory cascades to the ultimate outcome. We will also investigate, at the cellular level, in human airway epithelial cells of normal and CF phenotype, the spectrum of inflammatory responses of the epithelial cell itself to pseudomonas and its products, including cytokines, eicosanoids, and the ability to support neutrophil migration. These studies should elucidate the relation of the CF genotype to the excessive inflammatory response and identify potential therapeutic targets in the inflammatory cascade. In addition. this project will supply samples to Dr. Berger's project and Dr. Prince project for studies of IL-10 and NF-kappaB respectively.
Showing the most recent 10 out of 18 publications
