Gene therapy for cystic fibrosis (CF) has great appeal, but initial results with viral vectors and lipid-mediated gene transfer has been disappointing, so alternative strategies will be necessary. Molecular conjugates directed at the serpin-enzyme complex receptor (SEC-R) have been effectively used to correct the Cl transport defect found in the nasal epithelium of CF mice. The molecular conjugates are comprised of a peptide ligand for the SEC-R covalently bound to polylysine. This complex binds to DNA through charge interactions, and the complete conjugate is ultimately condensed under high salt conditions. Correction of the ion transport defect is not observed when the DNA is condensed with polylysine without ligand or if the ligand complex is conjugated with the lac Z gene. The conditions for transfer to the nasal epithelium will be optimized and assessment of the Cl ion transport defect will be carried out with respect to its relationship to the increased Na absorption and the reduced expression of nitric oxide synthetase-2 (NOS-2) also associated with the mutation in mouse CFTR. In addition, the conditions for gene delivery to the trachea will also be determined in the context of a correction in the Cl transport defect. The impact of the correction in Cl transport in the lower airways will be correlated with any increases in NOS-2, IL-10 expression and a reduction in the hyper-inflammatory response associated with Pseudomonas challenge in the CF animals. Toxicity and the effects of repeated dosing will also be assessed. Finally, the SEC-R complexes will be intravenously injected and applied directly to measure gene transfer into alveolar macrophages and the airway luminal epithelium, respectively. Delivery of CFTR into the airways and the alveolar macrophages will be analyzed in terms of protection against the inflammatory response to Pseudomonas. This analysis will determine whether the CF epithelium or the macrophages are responsible for the excessive inflammatory response. If the project is successful a new gene transfer strategy for CF and other airway diseases will be developed and the role of CFTR delivery to the epithelium in mediating the secondary phenotypic consequences of CF.
