Role of Cftr genotype in the response to chronic Pseudomonas aeruginosa lung infection in mice

Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106 Submitted 12 November 2003 ; accepted in final form 2 July 2004 Patients with cystic fibrosis have a lesion in the cystic fibrosis transmembrane conductance regulator gene (CFTR), which 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 usually leading to the death of these patients. The exact mechanism(s) by which mutation in CFTR leads to lung infection and inflammation is not clear. Mice bearing different mutations in the murine homolog to CFTR ( Cftr ) (R117H, S489X, Y122X, and F508, all backcrossed to the C57BL/6J background) were compared with respect to growth and in their ability to respond to lung infection elicited with Pseudomonas aeruginosa -laden agarose beads. Body weights of mice bearing mutations in Cftr were significantly smaller than wild-type mice at most ages. The inflammatory responses to P. aeruginosa -laden agarose beads were comparable in mice of all four Cftr mutant genotypes with respect to absolute and relative cell counts in bronchoalveolar lavage fluid, and cytokine levels (TNF- , IL-1 , IL-6, macrophage inflammatory protein-2, and keratinocyte chemoattractant) and eicosanoid levels (PGE 2 and LTB 4 ) in epithelial lining fluid: the few small differences observed occurred only between cystic fibrosis mice bearing the S489X mutation and those bearing the knockout mutation Y122X. Thus we cannot implicate either misprocessing of CFTR or failure of CFTR to reach the plasma membrane in the genesis of the excess inflammatory response of CF mice. Therefore, it appears that any functional defect in CFTR produces comparable inflammatory responses to lung infections with P. aeruginosa . cystic fibrosis transmembrane conductance regulator gene; agarose beads; mutation; inflammation Address for reprint requests and other correspondence: A. M. van Heeckeren, Case Western Reserve Univ. School of Medicine, Div. of Pediatric Pulmonology, Biomedical Research Bldg. 827, 2109 Adelbert Rd., Cleveland, OH 44106-4948 (E-mail: anna.vanheeckeren{at}case.edu )