A20 as an immune tolerance factor can determine islet transplant outcomes

Zammit, Nathan W.; Walters, Stacey N.; Seeberger, Karen; O’Connell, Philip J.; Korbutt, Gregory S.; Grey, Shane T.

doi:10.1172/jci.insight.131028

Cited by 29 publications

(33 citation statements)

References 79 publications

(112 reference statements)

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“…Endothelial cells taken from single A20‐engineered animals showed resistance to TNF‐induced apoptosis and reduced pro‐inflammatory responses, 65 consistent with the cytoprotective role of endogenous A20 in endothelial cells 66,67 . Forced expression of A20 in syngeneic rodent islet grafts reduced the islet mass needed for successful restoration of euglycemia, 36 whereas forced A20 expression in islet allografts promoted Treg‐dependent tolerance and long‐term allograft survival 32 . Mechanistically, forced A20‐expression in rodent islet grafts suppressed NF‐κB signaling and provided anti‐inflammatory, anti‐apoptotic, and pro‐tolerance promoting functions 32,34,36 .…”

Section: Discussionmentioning

confidence: 69%

“…NPIs treated with human TNF showed high expression of Tnfaip3 mRNA suggesting that as for rodent and human islets, 34,35 Tnfaip3 is a part of the natural physiological response to inflammatory stress (Figure 1A‐C). This suggested that as for human and mouse islet grafts, 32,36 forced expression of A20 might be cytoprotective for NPI grafts. Transduction of NPIs with a recombinant adenoviral vector encoding GFP under the cytomegalovirus (CMV) promoter (rAd.GFP) at a multiplicity of infection (MOI) of 20 resulted in ~80% GFP + cells, demonstrating that vectors derived from Ad5 could be used to deliver therapeutic payload to NPIs (Figure 1D).…”

Section: Resultsmentioning

confidence: 99%

“…In this respect, the cytoplasmic ubiquitin‐editing enzyme A20, 29 encoded by the TNFAIP3 gene, may represent a potential gene therapy candidate for ameliorating the xenogeneic inflammatory response 31 . A20 is an essential regulator of islet inflammatory homeostasis 32,33 by virtue of its function to negatively regulate NF‐κB activation and apoptosis induction in islets 34 and suppress islet inflammation 32 . A20 is induced in islets as part of their natural physiologic response to inflammatory stress, 35 and forced expression of A20 in mouse or human islets does not impair glucose sensing or insulin secretion, 32,36 suggesting A20 would present a safe candidate for islet engineering 31 .…”

Section: Introductionmentioning

confidence: 99%

“…A20 is an essential regulator of islet inflammatory homeostasis 32,33 by virtue of its function to negatively regulate NF‐κB activation and apoptosis induction in islets 34 and suppress islet inflammation 32 . A20 is induced in islets as part of their natural physiologic response to inflammatory stress, 35 and forced expression of A20 in mouse or human islets does not impair glucose sensing or insulin secretion, 32,36 suggesting A20 would present a safe candidate for islet engineering 31 . Mouse islet transplant studies have demonstrated that forced expression of A20 can reduce the size of the islet graft mass needed to achieve metabolic control 36 and that A20 expression can promote islet allograft tolerance by engendering Tregs at the graft site 32 …”

Section: Introductionmentioning

confidence: 99%

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Selection of a novel AAV2/TNFAIP3 vector for local suppression of islet xenograft inflammation

Zammit

Seeberger

Zamerli

et al. 2020

Xenotransplantation

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Background Neonatal porcine islets (NPIs) can restore glucose control in mice, pigs, and non‐human primates, representing a potential abundant alternative islet supply for clinical beta cell replacement therapy. However, NPIs are vulnerable to inflammatory insults that could be overcome with genetic modifications. Here, we demonstrate in a series of proof‐of‐concept experiments the potential of the cytoplasmic ubiquitin‐editing protein A20, encoded by the TNFAIP3 gene, as an NPI cytoprotective gene. Methods We forced A20 expression in NPI grafts using a recombinant adenovirus 5 (Ad5) vector and looked for impact on TNF‐stimulated NF‐κB activation and NPI graft function. As adeno‐associated vectors (AAV) are clinically preferred vectors but exhibit poor transduction efficacy in NPIs, we next screened a series of AAV serotypes under different transduction protocols for their ability achieve high transduction efficiency and suppress NPI inflammation without impacting NPI maturation. Results Forcing the expression of A20 in NPI with Ad5 vector blocked NF‐κB activation by inhibiting IκBα phosphorylation and degradation, and reduced the induction of pro‐inflammatory genes Cxcl10 and Icam1. A20‐expressing NPIs also exhibited superior functional capacity when transplanted into diabetic immunodeficient recipient mice, evidenced by a more rapid return to euglycemia and improved GTT compared to unmodified NPI grafts. We found AAV2 combined with a 14‐day culture period maximized NPI transduction efficiency (>70% transduction rate), and suppressed NF‐κB‐dependent gene expression without adverse impact upon NPI maturation. Conclusion We report a new protocol that allows for high‐efficiency genetic modification of NPIs, which can be utilized to introduce candidate genes without the need for germline engineering. This approach would be suitable for preclinical and clinical testing of beneficial molecules. We also report for the first time that A20 is cytoprotective for NPI, such that A20 gene therapy could aid the clinical development of NPIs for beta cell replacement.

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Section: Discussionmentioning

confidence: 69%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Selection of a novel AAV2/TNFAIP3 vector for local suppression of islet xenograft inflammation

Zammit

Seeberger

Zamerli

et al. 2020

Xenotransplantation

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“…www.nature.com/scientificreports/ how a series of A20 coding variants that cause a decrease in phosphorylation at Ser381 also decrease A20's NF-κB inhibitory activity in a graded manner, with a corresponding reduction in the ability of A20 to control inflammatory homeostasis in vivo. Such coding variants can have medical relevance, they may be beneficial by increasing protective immunity to pathogens 13 , however increased tissue inflammation may also be detrimental in situations including autoimmune disease 7 and organ transplantation 46 .…”

Section: 3%mentioning

confidence: 99%

A zebrafish functional genomics model to investigate the role of human A20 variants in vivo

Cultrone

Zammit

Self

et al. 2020

Sci Rep

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Germline loss-of-function variation in TNFAIP3, encoding A20, has been implicated in a wide variety of autoinflammatory and autoimmune conditions, with acquired somatic missense mutations linked to cancer progression. Furthermore, human sequence data reveals that the A20 locus contains ~ 400 non-synonymous coding variants, which are largely uncharacterised. The growing number of A20 coding variants with unknown function, but potential clinical impact, poses a challenge to traditional mouse-based approaches. Here we report the development of a novel functional genomics approach that utilizes a new A20-deficient zebrafish (Danio rerio) model to investigate the impact of TNFAIP3 genetic variants in vivo. A20-deficient zebrafish are hyper-responsive to microbial immune activation and exhibit spontaneous early lethality. Ectopic addition of human A20 rescued A20-null zebrafish from lethality, while missense mutations at two conserved A20 residues, S381A and C243Y, reversed this protective effect. Ser381 represents a phosphorylation site important for enhancing A20 activity that is abrogated by its mutation to alanine, or by a causal C243Y mutation that triggers human autoimmune disease. These data reveal an evolutionarily conserved role for TNFAIP3 in limiting inflammation in the vertebrate linage and show how this function is controlled by phosphorylation. They also demonstrate how a zebrafish functional genomics pipeline can be utilized to investigate the in vivo significance of medically relevant human TNFAIP3 gene variants.

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Local Immunomodulatory Strategies to Prevent Allo‐Rejection in Transplantation of Insulin‐Producing Cells

et al. 2021

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Islet transplantation has shown promise as a curative therapy for type 1 diabetes (T1D). However, the side effects of systemic immunosuppression and limited long-term viability of engrafted islets, together with the scarcity of donor organs, highlight an urgent need for the development of new, improved, and safer cell-replacement strategies. Induction of local immunotolerance to prevent allo-rejection against islets and stem cell derived cells has the potential to improve graft function and broaden the applicability of cellular therapy while minimizing adverse effects of systemic immunosuppression. In this mini review, recent developments in non-encapsulation, local immunomodulatory approaches for T1D cell replacement therapies, including islet/ cell modification, immunomodulatory biomaterial platforms, and co-transplantation of immunomodulatory cells are discussed. Key advantages and remaining challenges in translating such technologies to clinical settings are identified. Although many of the studies discussed are preliminary, the growing interest in the field has led to the exploration of new combinatorial strategies involving cellular engineering, immunotherapy, and novel biomaterials. Such interdisciplinary research will undoubtedly accelerate the development of therapies that can benefit the whole T1D population.

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A20 as an immune tolerance factor can determine islet transplant outcomes

Cited by 29 publications

References 79 publications

Selection of a novel AAV2/TNFAIP3 vector for local suppression of islet xenograft inflammation

Selection of a novel AAV2/TNFAIP3 vector for local suppression of islet xenograft inflammation

A zebrafish functional genomics model to investigate the role of human A20 variants in vivo

Local Immunomodulatory Strategies to Prevent Allo‐Rejection in Transplantation of Insulin‐Producing Cells

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