829. Preferential Transfection of Tissue Macrophages Following Intravenous Administration of sec-R Targeted hCFTR DNA Enhances Survival of CF Mice Inoculated with Pseudomonas aeruginosa Agar Beads

Abstract

Previously, we have shown that modification of Poly K compacted DNA complexes with a peptide ligand (C105Y) that binds the serpin enzyme complex receptor (sec-R) targets them to lung, liver and spleen after intravenous (IV) administration and to airway epithelial cells after intranasal (IN) administration in CF mice. Predominantly, tissue macrophages were transfected following IV dosing. Since both epithelial cells and macrophages express CFTR, we took advantage of these predilection to test whether CFTR delivery to macrophages or to epithelial cells protected against the consequences of Pseudomonas aeruginosa infection. We tested the effect of different routes of administration of sec-R targeted hCFTR, IN versus IV, on alleviating the consequence of the inoculation of CF mice with Pseudomonas aeruginosa laden agar beads. This method of infection induces inflammation in CF mice that models advanced disease in CF patients. Three groups of S489X/FABP-hCFTR mice (n=14 per group) housed in sterile micro-isolator cages were studied. Group 1 received a 50 μl bolus of a 1.0 M NaCl solution containing 10 μg of sec-R targeted compacted hCFTR plasmid (codes for human CFTR driven by the elongation factor 1 promoter) via the tail vein injection and 50 μl 1.0 M NaCl alone IN. Group 2 received 50 μl sec-R targeted hCFTR IN and 50 μl 1.0 M NaCl alone IV. Control group animals received 50 μl 1.0 M NaCl IV and IN. One day following dosing the mice were inoculated with 5 × 104 cfu P. aeruginosa embedded in agar beads, and their weights recoded. We monitored the mice for 10 days following infection. Ten of fourteen mice that received IV administration of sec-R targeted hCFTR survived the course of the experiment, while 6/14 survived for the IN dosed group and 3/14 survived for the control group (p=0.03, ANOVA). Weight loss that occurs following infection was reversed one day earlier on day 4 for groups 1 and 2 versus day 5 for control animals. These results were reproduced in 2 other experiments. In a fourth experiment, analysis of bronchoalveolar lavage (BAL) from animals similarly dosed and infected, but sacrificed on day 3 following infection revealed no significant differences in cell counts or production of TNF-α, IL-1β, IL-6, or mip-2/KC (mouse IL-8 homologs). Based on previous observations, these data suggest that delivery of hCFTR to tissue macrophages rather than airway epithelial cells allows for better protection against and/or recovery from infection in CF mice. Subtle decreases in cytokine production may be sufficient for this, although other event involved in infection and inflammation not assayed for by us may have been impacted more significantly by hCFTR gene transfer to tissue macrophages.