438. Development of a Myeloid Cell-Binding Adenovirus for the Potential Gene Therapy of Alpha-1 Anti-Trypsin Deficiency

Abstract

Alpha-1 anti-trypsin (A1AT) deficiency lung disease represents an ideal candidate for definitive gene therapy treatment. As the liver is the major locale for A1AT synthesis, the majority of gene therapy approaches have been directed towards induction of functional wild type A1AT within hepatocytes. Despite the diverse range of gene therapy strategies applied, the levels of serum A1AT achieved have not been sufficient to correct the elastase/anti-elastase balance within the lung. To this end, we hypothesized that in vivo gene delivery to pulmonary endothelium could provide A1AT augmentation of Epithelial Lining Fluid (ELF) more effectively than liver-based transduction methods. To re-target the expression of transgene in the lung, the knob domain of Ad5 has been successfully modified genetically in our lab. We have identified a novel peptide sequence called myeloid binding peptide (MBP) which increases the lung targeting. Based on this we created a recombinant adenovirus expressing A1AT with MBP in the fiber protein (AdMBPA1AT). When we injected this Ad systemically in mice we saw a high expression of the transgene in the serum in comparison to the control Ad expressing A1AT without MBP in the fiber protein. In order to confirm that the AdMBPA1AT localizes to the lung, we analyzed viral copy number using total DNA extracted from the organs of mice by qPCR and the expression of the protein in serum and ELF. Our strategy will test the hypothesis that A1AT deriving from the pulmonary endothelium can augment more effectively ELF A1AT to provide a corrective anti-elastase screen.