Among systems being developed for delivering and expressing the normal CFTR genes in the airways of CF patients, recombinant adenovirus (Ad) vectors are the farthest along in clinical trials in the United States. Chronic endobronchial inflammation associated with mucoid Pseudomonas infection afflicts most CF patients. However, the effects of this inflammatory airway environment in CF on gene delivery and expression by Ad vectors or other systems have not been carefully examined. Our major goals are to determine the effects of preexisting chronic airway inflammation on Ad-mediated gene delivery and expression in the lung, to identify mechanisms that mediate these effects, and to determine whether anti-inflammatory therapies can counter adverse effects of this inflammation on Ad-mediated gene transfer and expression. We hypothesize 1) that preexisting airway inflammation, as in CF, reduces Ad-mediated gene transfer and duration of transgene expression in the airways; 2) that this occurs directly by interference with Ad binding to epithelial cells, 3) that this also occurs indirectly by enhancement of specific immune responses that interfere with Ad-mediated gene delivery and expression; and 4) that anti-inflammatory therapies can counter adverse effects of inflammation on Ad-mediated gene delivery and expression.
Our specific aims are to: (1) Infect mice in the agarose bead model of chronic Pseudomonas lung infection, then determine if Ad-mediated gene transfer and duration of transgene expression in the airways are impaired. Cultural human airway epithelial cells in vitro will serve as a complementary method to examine the effects of CF sputum sol extracts or BAL fluid on Ad-mediated gene transfer (2) We will determine if CF secretions or their components interfere directly with Ad binding to epithelial cells and if this occurs by actions on the virus or the epithelial cells or both; (3) We will determine if chronically infected mice exhibit exaggerated Ad- specific humoral or cellular immune or inflammatory responses that reduce the extent or duration of transgene expression, and we will identify underlying mechanisms (.e.g. cytokine production or antigen presentation) whose enhancement may account for these exaggerated responses; 94) We will determine if treatment effective in reducing lung inflammation in chronically infected mice (i.e. antibodies to neutrophil and endothelial adhesion molecules or oral ibuprofen) will counter the adverse effects on inflammation on Ad-mediated gene transfer.
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