The principal goal of this proposal is to identify the intracellular signaling pathways in the lung that mediate the chronic processes of inflammation and infection associated with cystic fibrosis (CF). Preliminary data indicate that airway epithelial cell lines derived from CF trachea secrete massive levels of pro-inflammatory IL8. Consistently, gene therapy with CFTR, or drug therapy with CPX, suppresses baseline levels of IL8 secretion, while still allowing physiological IL8 secretion in response to the presence of bacteria. In normal epithelial cells, IL8 secretion is mediated by activation of the NFkB pathway, and pharmacogenomic studies indicate that a subset of NFkB pathway genes parallel the secretion of IL8 as a function of CFTR, CPX and exposure to P. aeruginosa. We have therefore hypothesized that the mechanism by which CFTR suppresses IL8 secretion from CF epithelial cells is by direct action on a pro-inflammatory intracellular signaling pathway. We wish to identify and study this pathway, and propose the following Specific Aims.
Aim #1 : To determine the signaling pathways by which CFTR and CPX suppress IL8 secretion from CF epithelial cells. We will use cDNA microarrays to identify genes whose expression is altered by CFTR, or by the presence of CPX.
Aim #2 : To identify the molecular mechanisms by which CFTR or CPX permit CF epithelial cells to respond physiologically to the presence of Pseudomonas aeruginosa. We will identify cis-acting elements within the IL8 promoter which mediate activation or suppression by CFTR, CPX and P. aeruginosa.
Aim #3 : To identify subdomains in CFTR that suppress IL8 secretion from CF epithelial cells. We will prepare viral vector constructs expressing CFTR from which different subdomains have been deleted, and identify the CFTR domain(s) required for suppression of IL8 secretion. Expectations, Innovation and Impact: Our expectations are that this research will generate valuable new knowledge that will be useful for the development of novel therapies for CF. The proposed hypothesis-driven research is innovative because biochemistry and hypothesis-driven pharmacogenomics have not previously been used in this way to investigate a single gene disease such as cystic fibrosis. The impact of this research will be to identify novel pathways by which CFTR affects the ability of lung epithelial cells to respond to bacterial assault.
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