We previously demonstrated that intraperitoneal delivery of adeno-associated virus serotype 8 (AAV8) stably transduces the pancreas, including the β cells in the pancreatic islets. We further demonstrated the ability to deliver and express target genes specifically in β cells for at least 6 months using a murine insulin promoter in a double-stranded, self-complementary AAV vector. Recombinant interleukin (IL)-2 has been shown to induce CD4+ CD25+ regulatory T cells (Tregs) in several mouse models of autoimmune disease. Here we evaluated the effects of double-stranded adeno-associated virus serotype 8-mouse insulin promoter (dsAAV8-mIP)-mediated delivery of2 to pancreatic β cells in non-obese diabetic (NOD) mice. AAV8-mIP-mediated gene expression of IL-2 to pancreatic β cells of 10-week-old NOD mice prevented the onset of hyperglycemia in NOD mice more in a dose-dependent manner with the lower dose of virus being more effective than a higher dose of AAV-mIP-IL-2 and IL-4. Moreover, the local β-cell expression of IL-2 increased the number of CD4+CD25 + FoxP3+ cells in the pancreatic lymph node (PLN) and SPL in both NOD and C57BL/6 mice. Taken together, these results demonstrate that local, low expression of mIL-2 in islets prevents progress of diabetes through the regulation of Tregs.
Bibliographical noteFunding Information:
Dr Robbins’ work has been funded by the NIH and the JDRF. This work was supported by grants AG024827, AG03307 and AR051456 from the National Institutes of Health and a program grant from the Juvenile Diabetes Research Foundation (JDRF) to PDR and RRF was supported by a T32 grant from NIH on Autoimmunity and Immunopathology. We thank Roland Tisch (University of North Carolina) for providing the AAV-mIP-IL-2 plasmid and Dewayne Faulkner (University of Pittsburgh) for his assistance with flow cytometry and Joan Nash (University of Pittsburgh) for her administrative support. We also thank Jing Zhao (The Scripps Research Institute, FL, USA) for her critical review of the manuscript.