The Journal of Immunology, 2003, 171: 469-476.
Copyright © 2003 by The American Association of Immunologists
More Stringent Conditions of Plasmid DNA Vaccination Are Required to Protect Grafted Versus Endogenous Islets in Nonobese Diabetic Mice 1
Christian Seifarth2,3,*,
Shannon Pop2,
,
Bo Liu*,
Carmen P. Wong* and
Roland Tisch4,*,
,
* Department of Microbiology and Immunology, School of Medicine,
Curriculum in Oral Biology, and
Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
Recurrent autoimmune destruction of the insulin-producing
cells is a key factor limiting successful islet graft transplantation in type I diabetic patients. In this study, we investigated the feasibility of using an Ag-specific plasmid DNA (pDNA)-based strategy to protect pro-islets that had developed from a neonatal pancreas implanted under the kidney capsule of nonobese diabetic (NOD) mice. NOD recipient mice immunized with pDNA encoding a glutamic acid decarboxylase 65 (GAD65)-IgFc fusion protein (JwGAD65), IL-4 (JwIL4), and IL-10 (pIL10) exhibited an increased number of intact pro-islets expressing high levels of insulin 15 wk posttransplant, relative to NOD recipient mice immunized with pDNA encoding a hen egg lysozyme (HEL)-IgFc fusion protein (JwHEL)+JwIL4 and pIL10 or left untreated. Notably, the majority of grafted pro-islets detected in JwGAD65+JwIL4- plus pIL10-treated recipients was free of insulitis. In addition, administration of JwGAD65+JwIL4+pIL10 provided optimal protection for engrafted islets compared with recipient NOD mice treated with JwGAD65+JwIL4 or JwGAD65+pIL10, despite effective protection of endogenous islets mediated by the respective pDNA treatments. Efficient protection of pro-islet grafts correlated with a marked reduction in GAD65-specific IFN-
reactivity and an increase in IL-10-secreting T cells. These results demonstrate that pDNA vaccination can be an effective strategy to mediate long-term protection of pro-islet grafts in an Ag-specific manner and that conditions are more stringent to suppress autoimmune destruction of grafted vs endogenous islets.
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