American Society of Gene Therapy, 12th Annual Meeting, May 27-30, San Diego, CA. Abstract #950039, "Durable Multicomponent Vaccine Suppression of Diabetes., B. Denes, I. Fodor and W. Langridge, Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Loma Linda, CA. 92350. ( 5/2009 )
In this study, fusion genes encoding the diabetes autoantigen glutamic acid decarboxylase (GAD), linked to the immunostimulatory cholera toxin B subunit (CTB-GAD) were delivered alone and in combination with the anti-inflammatory cytokine IL-10 by vaccinia virus infection of juvenile NOD mice. The mice were assessed for long term protection against diabetes progression by measurement of blood glucose levels from 11 to 63 wk of age. Approximately 80% of the mice inoculated with PBS, empty plasmid DNA or parental vaccinia developed hyperglycemia by 33 weeks of age. However, only 55% of the mice inoculated with VV-CTB::GAD and only 20% of mice co-inoculated with VV-CTB::GAD + VV-IL10 developed hyperglycemia over this time period. No further increase in blood glucose levels or diabetes incidence occurred in all immunized animal groups from 33 to 64 wk of age suggesting re-establishment of immunological homeostasis and permanent protection against further diabetes development. Histological analysis of pancreatic tissues isolated from mice inoculated with PBS, empty plasmid or vaccinia virus alone showed almost 100% peri-islet and intra-islet inflammation (insulitis). However, mice inoculated with virus containing the CTB-GAD fusion gene showed an approximate 50% reduction in insulitis. Further, mice co-inoculated with vaccinia virus containing the CTB-GAD and IL-10 genes showed an approximate 75% reduction in pancreatic inflammation. In contrast to un-inoculated mice, splenocytes isolated from 64 wk old mice co-vaccinated with rVV-CTB::GAD and rVV-IL-10 showed a significant reduction in inflammatory IFN-( cytokine secretion and increased secretion of the anti-inflammatory cytokine IL-10. In contrast to individual diabetes immunosuppression therapies, we demonstrate here that combinatorial vaccination strategies relying on vaccinia virus co-delivery of immuno-enhanced autoantigen and anti-inflammatory cytokine DNAs restore effective and durable immunologic homeostasis in NOD mice through suppression of diabetes hyperglycemia to normal blood glucose levels throughout the majority of the lifetime of the prediabetic animal. This effective and inexpensive multifactorial diabetes therapy can now be advanced for clinical confirmation in patients afflicted with or likely to develop Type 1 diabetes.