UNIVERSITY OF MINNESOTA
Suppression of Pancreas Autoimmunity Using Endogenously Expanded Regulatory T Cells
Ehren Rudolph1, Sajjad Soltani1, Erik Finger1.
1Transplant Surgery, University of Minnesota, Minneapolis, MN, United States
Background: Treatment with regulatory T cells (Tregs) has shown efficacy in preventing autoimmunity in animal models of type 1 diabetes. Tregs are currently being tested to prevent allograft rejection for kidney transplant. Clinically, isolation and ex vivo expansion of Tregs is difficult as well as consuming of both time and materials. Endogenously expanded Tregs have recently been described using an antibody against tumor necrosis factor super family receptor 25 (clone 4C12). This causes a robust expansion of Tregs to nearly 35 percent of CD4+ cells, and treatment with 4C12 was able to mildly prolong allograft survival in a fully mismatched model (1). The effect of endogenously expanded Tregs on autoimmunity has not been reported. Given the aggressive autoimmune response to panceas or islet grafts following transplant in diabetic recipients, we investigated the effect of endogenously expanded Tregs at preventing autoimmune islet destruction in animal models.
Methods: Using the cyclophosphamide model of accelerated diabetes, young male nonobese diabetic (NOD) mice were injected with cyclophosphamide. 24 hours later, mice were treated with or without 4C12 antibody and diabetes incidence was monitored. For the adoptive transfer study, lymphocytes were isolated from the spleen of spontaneously diabetic female NOD mice. 20 million lymphocytes were injected via IP injection into young NOD scid gamma (NSG) mice. 24 hours after adoptive lymphocyte transfer, recipient mice were injected with 4C12 antibody. Recipient mice were monitored for diabetes development. To assess the effect of endogenously expanded Tregs at preventing islet graft loss following transplant in both the alloimmune and autoimmune settings, chemically diabetic B6 mice were transplanted with 550 islets under the kidney capsule using Balbc donor islets. Spontaneously diabetic female NOD mice were transplanted using NSG donor islets. Recipients were treated with or without 4C12 four days prior to transplant. Mice were monitored for disease recurrence.
Results: Treatment with 4C12 expanded Tregs to greater than 35% of CD4 T cells. Tregs decreased over time to pretreatment levels. Repeated dosing of 4C12 was not able to prolong the elevation in Treg number. In the cyclophosphamide model, expansion of Tregs using 4C12 caused a significant delay and overall prevention of disease (disease-free mean survival time = 11.5 days in untreated mice versus undefined in 4C12 treatment (P = 0.03) (Fig 1). In the adoptive transfer model using lymphocytes from diabetic NOD mice into NSG mice, transfer of disease was significantly delayed by 4C12 treatment in the recipient mice. Disease-free mean survival time = 29 days in untreated mice versus 41 days with 4C12 treatment (P = 0.05) (Fig 2). Preliminary data suggest a prolongation of graft survival following islet transplant with 4C12 treatment in B6 mice but this has not reached significance given low numbers.
Conclusion: Our results suggest endogenously expanded Tregs show efficacy in preventing autoimmune pancreatic destruction in multiple models. These findings support further investigation of endogenously expanded Tregs for preventing graft loss following islet transplant as well as in preventing primary diabetes. Endogenous Treg expansion did not fully protect from diabetes development in any model, suggesting that strategies to increase expanded Treg longevity or improve antigen specificity may be required for full protection.
 Wolf D, et al. Transplantation. 2012 Sep 27;94(6):569-74.
11:00 - 12:30
|Islet Immunity and Tolerance||Suppression of Pancreas Autoimmunity Using Endogenously Expanded Regulatory T Cells||Plenary Room 1|