Porcine Islets Engineered with SA-FasL Protein Induces Robust Tolerance in Mice through CD4+CD25+FoxP3+ Treg Cells.

Porcine Islets Engineered with SA-FasL Protein Induces Robust Tolerance in Mice through CD4⁺CD25⁺FoxP3⁺ Treg Cells.

K. Woodward,¹ H. Zhao,¹ H. Shirwan,¹ F. Wang,¹ M. Graham,² B. Hering,² E. Yolcu.¹

¹Institute for Cellular Therapeutics and Department of Microbiology and Immunology, University of Louisville, Louisville, KY
²Schulze Diabetes Institute and Department of Surgery, University of Minnesota, Minneapolis, MN.

Meeting: 2016 American Transplant Congress

Abstract number: B43

Keywords: Engraftment, Fas ligand, Immunosuppression, Xenotransplantation

Session Information

Session Name: Poster Session B: Allograft Rejection, Tolerance, and Xenotransplantation

Session Type: Poster Session

Date: Sunday, June 12, 2016

Session Time: 6:00pm-7:00pm

Presentation Time: 6:00pm-7:00pm

Location: Halls C&D

Introduction: We have shown that porcine islets engineered to transiently display SA-FasL protein on their surface establish tolerance in mice following transplantation under the kidney capsule or intraportally. This study was designed to elucidate the mechanistic basis of the observed tolerance.

Methods: Islet grafts, graft-draining LNs, and spleen were collected from C57BL/6.FoxP3^DTR/GFP recipients of SA-FasL-engineered porcine islets in a time course study (n=6/time point) on days 3, 6, 12 post-transplantation and at experimental end-points (>200 days). Lymphocytes were stained with antibodies to various cell surface markers to identify T effector, T effector memory, T central memory, induced and natural Treg cells, and various innate immune cells using flow cytometry. Lymphocytes were also analyzed for intracellular cytokines following ionomycin and PMA stimulation. Treg cells were depleted early or late post-transplantation using diphtheria toxin. Long-term mice also challenged with BALB/c allogeneic skin to test the immune competency and islet-specific tolerance.

Results: Long-term (>200 days) recipients of porcine islets rejected BALB/ skin grafts in an acute fashion (MST=11.3±1.0) without any detrimental effect on the survival of porcine islets, demonstrating immune competency and antigen-specificity of tolerance. Extensive lymphocyte phenotyping and intracellular cytokines established the increased ratio of Treg/T effectors and induced/natural Treg cells within graft draining LNs of long-term survivors as the correlate of tolerance for both intraportal and subrenal islet transplantation sites. Depletion of Treg cells early (15 days) or late (60 days) post-transplantation resulted in prompt graft rejection in both settings.

Conclusion: Immunomodulation with SA-FasL-engineered porcine islet grafts serves as an effective means of tolerance induction in a xenograft model. Tolerance appears to be localized to the graft and Treg cells are prerequisite for tolerance induction.

CITATION INFORMATION: Woodward K, Zhao H, Shirwan H, Wang F, Graham M, Hering B, Yolcu E. Porcine Islets Engineered with SA-FasL Protein Induces Robust Tolerance in Mice through CD4⁺CD25⁺FoxP3⁺ Treg Cells. Am J Transplant. 2016;16 (suppl 3).

To cite this abstract in AMA style:

Woodward K, Zhao H, Shirwan H, Wang F, Graham M, Hering B, Yolcu E. Porcine Islets Engineered with SA-FasL Protein Induces Robust Tolerance in Mice through CD4⁺CD25⁺FoxP3⁺ Treg Cells. [abstract]. Am J Transplant. 2016; 16 (suppl 3). https://atcmeetingabstracts.com/abstract/porcine-islets-engineered-with-sa-fasl-protein-induces-robust-tolerance-in-mice-through-cd4cd25foxp3-treg-cells/. Accessed May 9, 2025.

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