Human A2-CAR T cells reject HLA-A2+ human islets transplanted into mice without inducing graft versus host disease

Abstract

Background: Type 1 diabetes (T1D) is an autoimmune disease characterised by T cell mediated destruction of pancreatic beta-cells. Islet transplantation is an effective therapy, but its success is limited by islet quality and availability along with the need for immunosuppression. New approaches include use of stem cell-derived insulin-producing cells and immunomodulatory therapies, but a limitation is the paucity of reproducible animal models in which interactions between human immune cells and insulin-producing cells can be studied without the complication of xenogeneic graft-versus-host disease (xGVHD). Methods: We expressed an HLA-A2-specific chimeric antigen receptor (A2-CAR) in human CD4+ and CD8+ T cells and tested their ability to reject HLA-A2+ islets transplanted under the kidney capsule or anterior chamber of the eye of immunodeficient mice. T cell engraftment, islet function and xGVHD were assessed longitudinally. Results: The speed and consistency of A2-CAR T cells-mediated islet rejection varied depending on the number of A2-CAR T cells and the absence/presence of co-injected peripheral blood mononuclear cells (PBMCs). When <3 million A2-CAR T cells were injected, co-injection of PBMCs accelerated islet rejection but also induced xGVHD. In the absence of PBMCs, injection of 3 million A2-CAR T cells caused synchronous rejection of A2+ human islets within 1 week and without xGVHD for 12 weeks. Conclusions: Injection of A2-CAR T cells can be used to study rejection of human insulin-producing cells without the complication of xGVHD. The rapidity and synchrony of rejection will facilitate in vivo screening of new therapies designed to improve the success of islet-replacement therapies.

CAR-T Cells: A New Tool for Monitoring T-cell Alloreactivity?

“…In conclusion, the promising observations reported in this study by Ellis et al 8 on improving humanized mouse models helps us to better understand the biology of the T-cell–mediated rejection processes. This is of essential importance to further improve the success of transplantation, including islet-replacement therapies.…”

“…In this edition of Transplantation , Ellis et al 8 propose a new model: human A2-CAR T cells as a tool to study T-cell–mediated rejection of human islets transplanted into mice without the complication of xGVHD. CARs are genetically engineered receptors that provide specific properties to immune cells including T cells, Treg, B cells, and natural killer cells.…”

“…Engineered autologous Treg are given to transplant recipients to dampen the allogeneic immune response or even to induce transplant tolerance, 6,7 whereas CAR T cells therapy is successful in cancer treatment. 10 Ellis et al 8 show that human T cells engineered with HLA-specific CARs can also be used as a “human” preclinical model to study the process of allograft rejection in humanized immunodeficient mice without the complication of xGVHD. 8 This newly developed method has clear advantages over currently used preclinical animal models.…”

“…10 Ellis et al 8 show that human T cells engineered with HLA-specific CARs can also be used as a “human” preclinical model to study the process of allograft rejection in humanized immunodeficient mice without the complication of xGVHD. 8 This newly developed method has clear advantages over currently used preclinical animal models. It provides the option for functional testing of human immune cell interactions in small animals while simultaneously eliminating some of the hurdles of animal studies by creating a “human” environment.…”

CAR Tregs mediate linked suppression and infectious tolerance in islet transplantation

“…50-150 HLA-A2 + NOD islets were handpicked from pre-diabetic, 6-11 week old mice, transplanted into the left anterior chamber of the eye (ACE) of NSG mice, and allowed to engraft for at least 2 weeks. The ACE is a validated location to study islet-directed auto-and alloimmunity (30)(31)(32)(33)(34): in NOD mice, ACE islet transplants are subject to autoimmune attack at the same rate as islets in the native pancreas (30).…”