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Local expression of indoleamine 2,3 dioxygenase in syngeneic fibroblasts significantly prolongs survival of an engineered three-dimensional islet allograft.

Jalili RB, Forouzandeh F, Rezakhanlou AM, Hartwell R, Medina A, Warnock GL, Larijani B, Ghahary A - Diabetes (2010)

Bottom Line: Local expression of IDO suppressed effector T-cells at the graft site, induced a Th2 immune response shift, generated an anti-inflammatory cytokine profile, delayed alloantibody production, and increased number of regulatory T-cells in draining lymph nodes, which resulted in antigen-specific impairment of T-cell priming.Local IDO expression prevents cellular and humoral alloimmune responses against islets and significantly prolongs islet allograft survival without systemic antirejection treatments.This promising finding proves the potent local immunosuppressive activity of IDO in islet allografts and sets the stage for development of a long-lasting nonrejectable islet allograft using stable IDO induction in bystander fibroblasts.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.

ABSTRACT

Objective: The requirement of systemic immunosuppression after islet transplantation is of significant concern and a major drawback to clinical islet transplantation. Here, we introduce a novel composite three-dimensional islet graft equipped with a local immunosuppressive system that prevents islet allograft rejection without systemic antirejection agents. In this composite graft, expression of indoleamine 2,3 dioxygenase (IDO), a tryptophan-degrading enzyme, in syngeneic fibroblasts provides a low-tryptophan microenvironment within which T-cells cannot proliferate and infiltrate islets.

Research design and methods: Composite three-dimensional islet grafts were engineered by embedding allogeneic mouse islets and adenoviral-transduced IDO-expressing syngeneic fibroblasts within collagen gel matrix. These grafts were then transplanted into renal subcapsular space of streptozotocin diabetic immunocompetent mice. The viability, function, and criteria for graft take were then determined in the graft recipient mice.

Results: IDO-expressing grafts survived significantly longer than controls (41.2 +/- 1.64 vs. 12.9 +/- 0.73 days; P < 0.001) without administration of systemic immunesuppressive agents. Local expression of IDO suppressed effector T-cells at the graft site, induced a Th2 immune response shift, generated an anti-inflammatory cytokine profile, delayed alloantibody production, and increased number of regulatory T-cells in draining lymph nodes, which resulted in antigen-specific impairment of T-cell priming.

Conclusions: Local IDO expression prevents cellular and humoral alloimmune responses against islets and significantly prolongs islet allograft survival without systemic antirejection treatments. This promising finding proves the potent local immunosuppressive activity of IDO in islet allografts and sets the stage for development of a long-lasting nonrejectable islet allograft using stable IDO induction in bystander fibroblasts.

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CD3+ and FOXP3+ cells infiltrating into composite islet grafts and in draining lymph nodes. Graft-recipient mice were killed at indicated time points posttransplantation. Composite islet grafts were then retrieved and subjected to double immunofluorescence staining for CD3 and insulin or FOXP3. A: Composite grafts in untreated, mock vector–infected, and IDO-expressing fibroblast graft at 2 weeks posttransplantation and IDO graft after 5 weeks posttransplantation. The lower panels show high magnification of the indicated area of the upper panels. Note that in the IDO-expressing graft, CD3+ cells accumulated in the border of the graft and kidney tissue but did not infiltrate the graft. Scale bars in the low- and high-magnification panels equal 100 and 20 μm, respectively. B and C: FOXP3 immunofluorescence staining of composite grafts (B) and graft draining lymph nodes (C). Untreated, mock vector, and IDO grafts at 2 weeks posttransplantation and IDO grafts after 5 weeks posttransplantation. Scale bar: 50 μm. (A high-quality digital representation of this figure is available in the online issue.)
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Figure 3: CD3+ and FOXP3+ cells infiltrating into composite islet grafts and in draining lymph nodes. Graft-recipient mice were killed at indicated time points posttransplantation. Composite islet grafts were then retrieved and subjected to double immunofluorescence staining for CD3 and insulin or FOXP3. A: Composite grafts in untreated, mock vector–infected, and IDO-expressing fibroblast graft at 2 weeks posttransplantation and IDO graft after 5 weeks posttransplantation. The lower panels show high magnification of the indicated area of the upper panels. Note that in the IDO-expressing graft, CD3+ cells accumulated in the border of the graft and kidney tissue but did not infiltrate the graft. Scale bars in the low- and high-magnification panels equal 100 and 20 μm, respectively. B and C: FOXP3 immunofluorescence staining of composite grafts (B) and graft draining lymph nodes (C). Untreated, mock vector, and IDO grafts at 2 weeks posttransplantation and IDO grafts after 5 weeks posttransplantation. Scale bar: 50 μm. (A high-quality digital representation of this figure is available in the online issue.)

Mentions: Double staining of grafts for CD3 and insulin showed very few insulin-producing cells and dense T-cell infiltration in both untreated and mock vector–infected controls at the end of the second week posttransplantation (Fig. 3A). In contrast, islets in IDO-expressing grafts were strongly stained for insulin and maintained their normal architecture with minimal infiltration of T-cells at the same time point (two weeks posttransplant; Fig. 3A). A remarkable finding was that T-cells densely accumulated at the interface between IDO-expressing graft and kidney tissue but did not penetrate into the composite graft (IDO 2 weeks posttransplant [Figs. 2I and 3A]). However, T-cells started to infiltrate IDO vector–infected grafts by the end of the fifth week posttransplant (Fig. 3A). While FOXP3 immunostaining revealed very few intragraft FOXP3+ cells in all experimental groups (Fig. 3B), more FOXP3+ cells were present in graft-draining lymph nodes of IDO-expressing recipients at week two but not week five posttransplant (Fig. 3C).


Local expression of indoleamine 2,3 dioxygenase in syngeneic fibroblasts significantly prolongs survival of an engineered three-dimensional islet allograft.

Jalili RB, Forouzandeh F, Rezakhanlou AM, Hartwell R, Medina A, Warnock GL, Larijani B, Ghahary A - Diabetes (2010)

CD3+ and FOXP3+ cells infiltrating into composite islet grafts and in draining lymph nodes. Graft-recipient mice were killed at indicated time points posttransplantation. Composite islet grafts were then retrieved and subjected to double immunofluorescence staining for CD3 and insulin or FOXP3. A: Composite grafts in untreated, mock vector–infected, and IDO-expressing fibroblast graft at 2 weeks posttransplantation and IDO graft after 5 weeks posttransplantation. The lower panels show high magnification of the indicated area of the upper panels. Note that in the IDO-expressing graft, CD3+ cells accumulated in the border of the graft and kidney tissue but did not infiltrate the graft. Scale bars in the low- and high-magnification panels equal 100 and 20 μm, respectively. B and C: FOXP3 immunofluorescence staining of composite grafts (B) and graft draining lymph nodes (C). Untreated, mock vector, and IDO grafts at 2 weeks posttransplantation and IDO grafts after 5 weeks posttransplantation. Scale bar: 50 μm. (A high-quality digital representation of this figure is available in the online issue.)
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2927944&req=5

Figure 3: CD3+ and FOXP3+ cells infiltrating into composite islet grafts and in draining lymph nodes. Graft-recipient mice were killed at indicated time points posttransplantation. Composite islet grafts were then retrieved and subjected to double immunofluorescence staining for CD3 and insulin or FOXP3. A: Composite grafts in untreated, mock vector–infected, and IDO-expressing fibroblast graft at 2 weeks posttransplantation and IDO graft after 5 weeks posttransplantation. The lower panels show high magnification of the indicated area of the upper panels. Note that in the IDO-expressing graft, CD3+ cells accumulated in the border of the graft and kidney tissue but did not infiltrate the graft. Scale bars in the low- and high-magnification panels equal 100 and 20 μm, respectively. B and C: FOXP3 immunofluorescence staining of composite grafts (B) and graft draining lymph nodes (C). Untreated, mock vector, and IDO grafts at 2 weeks posttransplantation and IDO grafts after 5 weeks posttransplantation. Scale bar: 50 μm. (A high-quality digital representation of this figure is available in the online issue.)
Mentions: Double staining of grafts for CD3 and insulin showed very few insulin-producing cells and dense T-cell infiltration in both untreated and mock vector–infected controls at the end of the second week posttransplantation (Fig. 3A). In contrast, islets in IDO-expressing grafts were strongly stained for insulin and maintained their normal architecture with minimal infiltration of T-cells at the same time point (two weeks posttransplant; Fig. 3A). A remarkable finding was that T-cells densely accumulated at the interface between IDO-expressing graft and kidney tissue but did not penetrate into the composite graft (IDO 2 weeks posttransplant [Figs. 2I and 3A]). However, T-cells started to infiltrate IDO vector–infected grafts by the end of the fifth week posttransplant (Fig. 3A). While FOXP3 immunostaining revealed very few intragraft FOXP3+ cells in all experimental groups (Fig. 3B), more FOXP3+ cells were present in graft-draining lymph nodes of IDO-expressing recipients at week two but not week five posttransplant (Fig. 3C).

Bottom Line: Local expression of IDO suppressed effector T-cells at the graft site, induced a Th2 immune response shift, generated an anti-inflammatory cytokine profile, delayed alloantibody production, and increased number of regulatory T-cells in draining lymph nodes, which resulted in antigen-specific impairment of T-cell priming.Local IDO expression prevents cellular and humoral alloimmune responses against islets and significantly prolongs islet allograft survival without systemic antirejection treatments.This promising finding proves the potent local immunosuppressive activity of IDO in islet allografts and sets the stage for development of a long-lasting nonrejectable islet allograft using stable IDO induction in bystander fibroblasts.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.

ABSTRACT

Objective: The requirement of systemic immunosuppression after islet transplantation is of significant concern and a major drawback to clinical islet transplantation. Here, we introduce a novel composite three-dimensional islet graft equipped with a local immunosuppressive system that prevents islet allograft rejection without systemic antirejection agents. In this composite graft, expression of indoleamine 2,3 dioxygenase (IDO), a tryptophan-degrading enzyme, in syngeneic fibroblasts provides a low-tryptophan microenvironment within which T-cells cannot proliferate and infiltrate islets.

Research design and methods: Composite three-dimensional islet grafts were engineered by embedding allogeneic mouse islets and adenoviral-transduced IDO-expressing syngeneic fibroblasts within collagen gel matrix. These grafts were then transplanted into renal subcapsular space of streptozotocin diabetic immunocompetent mice. The viability, function, and criteria for graft take were then determined in the graft recipient mice.

Results: IDO-expressing grafts survived significantly longer than controls (41.2 +/- 1.64 vs. 12.9 +/- 0.73 days; P < 0.001) without administration of systemic immunesuppressive agents. Local expression of IDO suppressed effector T-cells at the graft site, induced a Th2 immune response shift, generated an anti-inflammatory cytokine profile, delayed alloantibody production, and increased number of regulatory T-cells in draining lymph nodes, which resulted in antigen-specific impairment of T-cell priming.

Conclusions: Local IDO expression prevents cellular and humoral alloimmune responses against islets and significantly prolongs islet allograft survival without systemic antirejection treatments. This promising finding proves the potent local immunosuppressive activity of IDO in islet allografts and sets the stage for development of a long-lasting nonrejectable islet allograft using stable IDO induction in bystander fibroblasts.

Show MeSH
Related in: MedlinePlus