Limits...
Manipulating IL-2 availability amid presentation of donor MHC antigens suppresses murine alloimmune responses by inducing regulatory T cells.

Zhang S, Dai H, Wan N, Moore Y, Dai Z - PLoS ONE (2010)

Bottom Line: Importantly, MHCII + IL-2 induced FoxP3+ Treg cells in both spleens and grafts and suppressed graft-infiltrating CD4+ cell proliferation, whereas MHCI + IL-2/anti-IL-2 mainly inhibited graft-infiltrating CD8+ cell proliferation and donor-specific CTL activity.The combined protocol plus rapamycin treatment further reduced both CD4+ and CD8+ T cell proliferation as well as donor-specific CTL activity but spared FoxP3+ Treg cells.Depleting CD25+ Treg cells or adoptive transfer of pre-sensitized CD8+ T cells abolished this long-term allograft survival.

View Article: PubMed Central - PubMed

Affiliation: Center for Biomedical Research, University of Texas Health Science Center, Tyler, Texas, United States of America.

ABSTRACT

Background: Major histocompatibility complex (MHC) antigens are important for alloimmune responses as well as immune tolerance. Previous studies have shown that presentation of donor MHC antigens by donor-specific transfusion prior to or upon transplantation promotes transplant tolerance induced by other agents. However, it is unclear whether presentation of donor MHC antigens by DNA vaccination induces long-term allograft survival.

Methodology/principal findings: We investigated whether presentation of MHC class-II and/or class-I donor antigens by DNA vaccination suppresses alloimmune responses and promotes long-term allograft acceptance. We initially found that presentation of both MHC donor antigens by DNA vaccination itself prior to transplantation fails to significantly prolong islet allograft survival in otherwise untreated mice. However, islet allograft survival was significantly prolonged when MHC class-II DNA vaccination was accompanied with IL-2 administration (MHCII + IL-2) while MHC class-I DNA vaccination was followed by IL-2 and subsequent neutralizing anti-IL-2 treatments (MHCI + IL-2/anti-IL-2). Especially, this protocol promoted long-term allograft survival in the majority of recipients (57%) when combined with low doses of rapamycin post-transplantation. Importantly, MHCII + IL-2 induced FoxP3+ Treg cells in both spleens and grafts and suppressed graft-infiltrating CD4+ cell proliferation, whereas MHCI + IL-2/anti-IL-2 mainly inhibited graft-infiltrating CD8+ cell proliferation and donor-specific CTL activity. The combined protocol plus rapamycin treatment further reduced both CD4+ and CD8+ T cell proliferation as well as donor-specific CTL activity but spared FoxP3+ Treg cells. Depleting CD25+ Treg cells or adoptive transfer of pre-sensitized CD8+ T cells abolished this long-term allograft survival.

Conclusions/significance: Manipulating IL-2 availability during presentation of MHC class-II and class-I donor antigens by DNA vaccination pre-transplantation induces Treg cells, suppresses alloimmune responses and promotes long-term allograft survival.

Show MeSH

Related in: MedlinePlus

The absolute number of FoxP3-positive Treg cells in allografts.Prior to transplantation, B6 mice were immunized with donor MHC DNA vaccines and/or treated with IL-2 regimen as described in Figure 1. One and two weeks after receiving Balb/C islets under the kidney capsule, recipient mice were sacrificed and graft-infiltrating cells were isolated and stained for FoxP3 to quantify FoxP3+ Treg cells by FACS. FoxP3+ cell numbers were calculated by the formula that total cell numbers per kidney time the percentage of FoxP3+ cells (%). Results are shown as mean ± SEM from four independent experiments (*P<0.05, #P>0.05, and &P>0.05).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2807454&req=5

pone-0008756-g004: The absolute number of FoxP3-positive Treg cells in allografts.Prior to transplantation, B6 mice were immunized with donor MHC DNA vaccines and/or treated with IL-2 regimen as described in Figure 1. One and two weeks after receiving Balb/C islets under the kidney capsule, recipient mice were sacrificed and graft-infiltrating cells were isolated and stained for FoxP3 to quantify FoxP3+ Treg cells by FACS. FoxP3+ cell numbers were calculated by the formula that total cell numbers per kidney time the percentage of FoxP3+ cells (%). Results are shown as mean ± SEM from four independent experiments (*P<0.05, #P>0.05, and &P>0.05).

Mentions: To further quantify Treg cells in grafts after transplantation, mice that were immunized and/or treated with IL-2/anti-IL-2 were sacrificed one and two weeks after islet transplantation, and graft-infiltrating cells were isolated and analyzed to determine the absolute numbers of FoxP3+ Treg cells per kidney. As shown in Figure 4, treatments with IL-2, anti-IL-2, or together with MHC I DNA vaccination prior to transplantation did not alter the numbers of Treg cells in grafts one week after islet transplantation. Neither did the vector control (data not shown in the figure). However, MHC II DNA vaccination significantly increased Treg cell numbers compared to control group (7.8±1.1 vs. 5.0±0.5, P<0.05) while Treg numbers were further increased in MHC II + IL-2 group compared to MHC II alone (14.6±1.9 vs. 7.8±1.1, P<0.05) one week after transplantation. Administration of rapamycin alone post-transplantation slightly but not significantly increased the numbers of Tregs in the grafts compared to the control (6.3±1.2 vs. 5.0±0.5, P>0.05). Rapamycin also did not significantly alter Treg numbers when combined with MHC II + MHC I plus IL-2 regimen (A+ B+ Rapa vs. A+ B: 16.2±2.3 vs. 15.1±2.1, P>0.05). The similar results were obtained two weeks after transplantation (Figure 4). Taken together, MHC II DNA vaccination alone or together with administration of IL-2 prior to transplantation dramatically increased the number of Treg cells in both spleens and grafts of recipients while addition of rapamycin after transplantation did not significantly alter the numbers of Treg cells in grafts. These findings suggest that donor MHC class-II, but not MHC class-I, DNA vaccination induces Treg cells and is more efficient when additional IL-2 is available.


Manipulating IL-2 availability amid presentation of donor MHC antigens suppresses murine alloimmune responses by inducing regulatory T cells.

Zhang S, Dai H, Wan N, Moore Y, Dai Z - PLoS ONE (2010)

The absolute number of FoxP3-positive Treg cells in allografts.Prior to transplantation, B6 mice were immunized with donor MHC DNA vaccines and/or treated with IL-2 regimen as described in Figure 1. One and two weeks after receiving Balb/C islets under the kidney capsule, recipient mice were sacrificed and graft-infiltrating cells were isolated and stained for FoxP3 to quantify FoxP3+ Treg cells by FACS. FoxP3+ cell numbers were calculated by the formula that total cell numbers per kidney time the percentage of FoxP3+ cells (%). Results are shown as mean ± SEM from four independent experiments (*P<0.05, #P>0.05, and &P>0.05).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2807454&req=5

pone-0008756-g004: The absolute number of FoxP3-positive Treg cells in allografts.Prior to transplantation, B6 mice were immunized with donor MHC DNA vaccines and/or treated with IL-2 regimen as described in Figure 1. One and two weeks after receiving Balb/C islets under the kidney capsule, recipient mice were sacrificed and graft-infiltrating cells were isolated and stained for FoxP3 to quantify FoxP3+ Treg cells by FACS. FoxP3+ cell numbers were calculated by the formula that total cell numbers per kidney time the percentage of FoxP3+ cells (%). Results are shown as mean ± SEM from four independent experiments (*P<0.05, #P>0.05, and &P>0.05).
Mentions: To further quantify Treg cells in grafts after transplantation, mice that were immunized and/or treated with IL-2/anti-IL-2 were sacrificed one and two weeks after islet transplantation, and graft-infiltrating cells were isolated and analyzed to determine the absolute numbers of FoxP3+ Treg cells per kidney. As shown in Figure 4, treatments with IL-2, anti-IL-2, or together with MHC I DNA vaccination prior to transplantation did not alter the numbers of Treg cells in grafts one week after islet transplantation. Neither did the vector control (data not shown in the figure). However, MHC II DNA vaccination significantly increased Treg cell numbers compared to control group (7.8±1.1 vs. 5.0±0.5, P<0.05) while Treg numbers were further increased in MHC II + IL-2 group compared to MHC II alone (14.6±1.9 vs. 7.8±1.1, P<0.05) one week after transplantation. Administration of rapamycin alone post-transplantation slightly but not significantly increased the numbers of Tregs in the grafts compared to the control (6.3±1.2 vs. 5.0±0.5, P>0.05). Rapamycin also did not significantly alter Treg numbers when combined with MHC II + MHC I plus IL-2 regimen (A+ B+ Rapa vs. A+ B: 16.2±2.3 vs. 15.1±2.1, P>0.05). The similar results were obtained two weeks after transplantation (Figure 4). Taken together, MHC II DNA vaccination alone or together with administration of IL-2 prior to transplantation dramatically increased the number of Treg cells in both spleens and grafts of recipients while addition of rapamycin after transplantation did not significantly alter the numbers of Treg cells in grafts. These findings suggest that donor MHC class-II, but not MHC class-I, DNA vaccination induces Treg cells and is more efficient when additional IL-2 is available.

Bottom Line: Importantly, MHCII + IL-2 induced FoxP3+ Treg cells in both spleens and grafts and suppressed graft-infiltrating CD4+ cell proliferation, whereas MHCI + IL-2/anti-IL-2 mainly inhibited graft-infiltrating CD8+ cell proliferation and donor-specific CTL activity.The combined protocol plus rapamycin treatment further reduced both CD4+ and CD8+ T cell proliferation as well as donor-specific CTL activity but spared FoxP3+ Treg cells.Depleting CD25+ Treg cells or adoptive transfer of pre-sensitized CD8+ T cells abolished this long-term allograft survival.

View Article: PubMed Central - PubMed

Affiliation: Center for Biomedical Research, University of Texas Health Science Center, Tyler, Texas, United States of America.

ABSTRACT

Background: Major histocompatibility complex (MHC) antigens are important for alloimmune responses as well as immune tolerance. Previous studies have shown that presentation of donor MHC antigens by donor-specific transfusion prior to or upon transplantation promotes transplant tolerance induced by other agents. However, it is unclear whether presentation of donor MHC antigens by DNA vaccination induces long-term allograft survival.

Methodology/principal findings: We investigated whether presentation of MHC class-II and/or class-I donor antigens by DNA vaccination suppresses alloimmune responses and promotes long-term allograft acceptance. We initially found that presentation of both MHC donor antigens by DNA vaccination itself prior to transplantation fails to significantly prolong islet allograft survival in otherwise untreated mice. However, islet allograft survival was significantly prolonged when MHC class-II DNA vaccination was accompanied with IL-2 administration (MHCII + IL-2) while MHC class-I DNA vaccination was followed by IL-2 and subsequent neutralizing anti-IL-2 treatments (MHCI + IL-2/anti-IL-2). Especially, this protocol promoted long-term allograft survival in the majority of recipients (57%) when combined with low doses of rapamycin post-transplantation. Importantly, MHCII + IL-2 induced FoxP3+ Treg cells in both spleens and grafts and suppressed graft-infiltrating CD4+ cell proliferation, whereas MHCI + IL-2/anti-IL-2 mainly inhibited graft-infiltrating CD8+ cell proliferation and donor-specific CTL activity. The combined protocol plus rapamycin treatment further reduced both CD4+ and CD8+ T cell proliferation as well as donor-specific CTL activity but spared FoxP3+ Treg cells. Depleting CD25+ Treg cells or adoptive transfer of pre-sensitized CD8+ T cells abolished this long-term allograft survival.

Conclusions/significance: Manipulating IL-2 availability during presentation of MHC class-II and class-I donor antigens by DNA vaccination pre-transplantation induces Treg cells, suppresses alloimmune responses and promotes long-term allograft survival.

Show MeSH
Related in: MedlinePlus