GENE-TRANSFER INTO THE AIRWAY EPITHELIUM OF ANIMALS BY TARGETING THE POLYMERIC IMMUNOGLOBULIN RECEPTOR

Genes of interest can be targeted specifically to respiratory epitheli al cells in intact animals with high efficiency by exploiting the rece ptor-mediated endocytosis of the polymeric immunoglobulin receptor. A DNA carrier, consisting of the Fab portion of polyclonal antibodies ra ised against rat secretory component covalently linked to poly-L-lysin e, was used to introduce plasmids containing different reporter genes into airway epithelial cells in vivo. We observed significant levels o f luciferase enzyme activity in protein extracts from the liver and lu ng, achieving maximum values of 13,795+/-4,431 and 346,954+/-199,120 i ntegrated light units (ILU) per milligram of protein extract, respecti vely. No luciferase activity was detected in spleen or heart, which do not express the receptor. Transfections using complexes consisting of an irrelevant plasmid (pCMV lacZ) bound to the bona fide carrier or t he expression plasmid (pGEMluc) bound to a carrier based on an irrelev ant Fab fragment resulted in background levels of luciferase activity in all tissues examined. Thus, only tissues that contain cells bearing the polymeric immunoglobulin receptor are transfected, and transfecti on cannot be attributed to the nonspecific uptake of an irrelevant car rier-DNA complex. Specific mRNA from the luciferase gene was also dete cted in the lungs of transfected animals. To determine which cells in the lung are transfected by this method, DNA complexes were prepared c ontaining expression plasmids with genes encoding the bacterial beta-g alactosidase or the human interleukin 2 receptor. Expression of these genes was localized to the surface epithelium of the airways and the s ubmucosal glands, and not the bronchioles and alveoli. Receptor-mediat ed endocytosis can be used to introduce functional genes into the resp iratory epithelium of rats, and may be a useful technique for gene the rapy targeting the lung.