Pancreatic islets engineered with a FasL protein induce systemic tolerance at the induction phase that evolves into long-term graft-localized immune privilege

Abstract

We have previously shown that pancreatic islets engineered to transiently display a modified form of FasL protein (SA‐FasL) on their surface survive indefinitely in allogeneic recipients without a need for chronic immunosuppression. Mechanisms that confer long‐term protection to allograft are yet to be elucidated. We herein demonstrated that immune protection evolves in two distinct phases; induction and maintenance. SA‐FasL‐engineered allogeneic islets survived indefinitely and conferred protection to a second set of donor‐matched, but not third‐party, unmanipulated islet grafts simultaneously transplanted under the contralateral kidney capsule. Protection at the induction phase involved a reduction in the frequency of proliferating alloreactive T cells in the graft‐draining lymph nodes, and required phagocytes and TGF‐β. At the maintenance phase, immune protection evolved into graft site‐restricted immune privilege as the destruction of long‐surviving SA‐FasL‐islet grafts by streptozotocin followed by the transplantation of a second set of unmanipulated islet grafts into the same site from the donor, but not third party, resulted in indefinite survival. The induced immune privilege required both CD4+CD25+Foxp3+ Treg cells and persistent presence of donor antigens. Engineering cell and tissue surfaces with SA‐FasL protein provides a practical, efficient, and safe means of localized immunomodulation with important implications for autoimmunity and transplantation.

Immune checkpoint CD47 molecule engineered islets mitigate instant blood-mediated inflammatory reaction and show improved engraftment following intraportal transplantation

“…Importantly, the engineering of islets with SA‐CD47 did not negatively impact their viability, metabolic activity, or insulin secretion. These findings are consistent with our published studies transiently displaying the SA‐FasL protein on the surface of islets for the regulation of alloreactive immune responses 35,55 . In an in vitro xenogeneic system, SA‐CD47‐engineered rat cells overcame phagocytosis by mouse macrophages.…”

“…These findings are consistent with our published studies transiently displaying the SA-FasL protein on the surface of islets for the regulation of alloreactive immune responses. 35,55 In an in vitro xenogeneic system, SA-CD47-engineered rat cells overcame phagocytosis by mouse macrophages. This observation is consistent with studies F I G U R E 4 SA-CD47 engineering protects islets from destruction by IBMIR in an in vitro loop assay.…”

“…71 The blockade of CD47/SIRPα pathway in this model resulted in the rejection of long-term tolerant kidney grafts, which was associated with the overexpression of MCP-1 and inflammatory macrophage signature. However, it remains to be investigated whether the transient display of SA-CD47 on allogeneic islets or cellular grafts is sufficient as a single agent or in combination with a modulator of adaptive immunity, such as SA-FasL, 35,39,55,72 is effective in inducing tolerance. In conclusion, rapid and transient display of SA-CD47 protein on the surface of tissues and cells to mitigate IBMIR provides a facile and clinically applicable platform with significant translational potential for transplantation of various tissue and cellular grafts.…”

Adenovirus-Mediated FasL Minigene Transfer Endows Transduced Cells with Killer Potential

“…Due to the inherent affinity for the liver, this system has been previously used in a study of lipid metabolism, the liver being the major source of plasma apolipoproteins [ 27 , 28 ]. Although under some pathological conditions the liver may be susceptible to apoptosis triggered by the Fas/FasL interaction [ 26 ], numerous studies have shown that therapeutic use of FasL in vivo does not cause liver toxicity [ 29 , 30 ]. Human CAR homologs are prevalently expressed in various species, including mice, rats, and pigs [ 31 , 32 ]; therefore, we chose a line of endothelial cells that are inherently resistant to FasL-induced apoptosis [ 33 ].…”

A novel prevascularized tissue-engineered chamber as a site for allogeneic and xenogeneic islet transplantation to establish a bioartificial pancreas

“…In theory, islets derived from animals (porcine islets) can solve the problem of organ shortage, but problems associated with strong rejection need to be solved in the future [ 43 ]. The mechanism of rejection following xenogeneic transplantation is extraordinarily complicated, as shown by the small number of reports of successful induction of xenografts [ 44 , 45 ]. In the present study, euglycemia was maintained in the TEC by an effective dual antibody treatment (anti-CD45RB plus anti-MR-1) after xenotransplantation from rats to C57 mice.…”