Adenovirus-Mediated Transduction of Intestinal CellsIn Vivo

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Abstract
The intestinal tract has many features that make it an attractive target for therapeutic gene transfer. In this study, replication-defective adenoviral vectors were used to explore parameters that may be important in administering gene therapy vectors to the intestine. After surgically accessing the intestine, an E1-, E3-deleted adenoviral vector encoding β-galactosidase (β-Gal) was directly injected into various regions of the small and large intestine of rats and rabbits. Significant transduction of the tissue was observed and histochemical staining was used to identify enterocytes as the primary targets of gene transfer. Expression of β-Gal did not differ substantially when the virus was administered to the duodenum, ileum, or colon. When the vector was directly administered to segments of the distal ileum containing a Peyer's patch, transgene expression was ~ 10-fold higher than in segments lacking a Peyer's patch. In the Peyer's patches, a high level of expression was localized to epithelial cells, potentially M cells, overlying the lymphoid follicle domes. Transduction of these cells could have application in DNA-mediated oral vaccination. Administration of an adenoviral vector encoding a secreted alkaline phosphatase to the lumen resulted in expression and secretion of this gene product into the circulation. This finding demonstrates the potential of enterocytes to serve as heterotopic sites for the synthesis of heterologous gene products that would be secreted into the lumen of the intestinal tract or into the bloodstream. Replication-defective adenoviral vectors were used to investigate the feasibility and usefulness of administering gene therapy vectors to transduce cells in the intestinal tract. By directly injecting recombinant adenovirus to the lumen of the intestine in rats and rabbits, we have shown that enterocytes in the duodenum, ileum, and colon are transduced, and that these cells do not differ substantially in their susceptibility to adenovirus-mediated transduction. Furthermore, we have demonstrated that administration of a vector encoding a secretory gene product to the lumen leads to expression and secretion of the gene product into the circulation. Finally, we have shown that transgene expression is markedly elevated in epithelial cells overlying Peyer's patches in the distal ileum. The studies reported in this paper further the notion that gene transfer to the intestinal tract shows therapeutic promise.