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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.

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Depleting CD25+ Treg cells or adoptive transfer of pre-sensitized CD8+ T cells abrogates long-term islet allograft survival.B6 mice were treated with MHC I + IL-2/anti-IL-2 and subsequent MHC II + IL-2 prior to transplantation, transplanted with Balb/C islets, and treated with low doses of rapamycin post-transplantation (A + B + Rapa). They were also treated with either depleting anti-CD25 Ab (A + B + Rapa + Anti-CD25) (□, n = 6) or control IgG (A + B + Rapa + Control IgG) (ν, n = 7), or received upon transplantation syngeneic CD8+CD25− (A + B + Rapa + CD8) (○, n = 7) or CD4+CD25− T cells (A + B + Rapa + CD4) (▵, n = 6) that were isolated from B6 mice pre-sensitized i.p. with irradiated Balb/C splenocytes two weeks earlier. Depleting CD25+ Treg cells or adoptive transfer of pre-sensitized CD8+, but not CD4+, T cells reversed long-term islet allograft survival induced by treatments with donor MHC DNA vaccination and IL-2 regimen prior to transplantation plus rapamycin treatment post-transplantation.
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pone-0008756-g007: Depleting CD25+ Treg cells or adoptive transfer of pre-sensitized CD8+ T cells abrogates long-term islet allograft survival.B6 mice were treated with MHC I + IL-2/anti-IL-2 and subsequent MHC II + IL-2 prior to transplantation, transplanted with Balb/C islets, and treated with low doses of rapamycin post-transplantation (A + B + Rapa). They were also treated with either depleting anti-CD25 Ab (A + B + Rapa + Anti-CD25) (□, n = 6) or control IgG (A + B + Rapa + Control IgG) (ν, n = 7), or received upon transplantation syngeneic CD8+CD25− (A + B + Rapa + CD8) (○, n = 7) or CD4+CD25− T cells (A + B + Rapa + CD4) (▵, n = 6) that were isolated from B6 mice pre-sensitized i.p. with irradiated Balb/C splenocytes two weeks earlier. Depleting CD25+ Treg cells or adoptive transfer of pre-sensitized CD8+, but not CD4+, T cells reversed long-term islet allograft survival induced by treatments with donor MHC DNA vaccination and IL-2 regimen prior to transplantation plus rapamycin treatment post-transplantation.

Mentions: Since donor MHC DNA vaccination and IL-2 regimen prior to transplantation induced Treg cells and promoted long-term allograft survival, we then asked whether this long-term allograft survival is dependent on Treg cells. The immunized B6 mice that also received IL-2 regimen prior to transplantation, as described in Methods section, were transplanted with Balb/C islets and treated with low dose of rapamycin as well as depleting anti-CD25 Ab or isotype control. As shown in Figure 7, we found that depleting CD25+ Treg cells abrogated the long-term islet allograft survival induced by MHC DNA vaccination plus IL-2 regimen pre-transplantation and the rapamycin treatment post-transplantation (MST = 25 days). Moreover, this long-term allograft survival could not be achieved at all in IL-2-deficient mice that lack CD25+ T cells (data not shown). On the other hand, the long-term allograft survival induced by this protocol was also reversed by the adoptive transfer of CD8+CD25− T cells that were isolated from mice that were sensitized i.p. with Balb/C splenocytes two weeks prior to the cell transfer (MST = 31 days). However, transfer of pre-sensitized CD4+CD25− counterparts did not significantly shorten allograft survival (MST = 92 vs. 102 days, P>0.05). These findings suggest that long-term allograft survival, induced by rapamycin post-transplantation and donor MHC DNA vaccination plus IL-2 regimen pre-transplantation, is dependent on CD25+ Treg cells and that adoptive transfer of allo-sensitized CD8+, but not CD4+, T cells prevents this long-term allograft survival.


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)

Depleting CD25+ Treg cells or adoptive transfer of pre-sensitized CD8+ T cells abrogates long-term islet allograft survival.B6 mice were treated with MHC I + IL-2/anti-IL-2 and subsequent MHC II + IL-2 prior to transplantation, transplanted with Balb/C islets, and treated with low doses of rapamycin post-transplantation (A + B + Rapa). They were also treated with either depleting anti-CD25 Ab (A + B + Rapa + Anti-CD25) (□, n = 6) or control IgG (A + B + Rapa + Control IgG) (ν, n = 7), or received upon transplantation syngeneic CD8+CD25− (A + B + Rapa + CD8) (○, n = 7) or CD4+CD25− T cells (A + B + Rapa + CD4) (▵, n = 6) that were isolated from B6 mice pre-sensitized i.p. with irradiated Balb/C splenocytes two weeks earlier. Depleting CD25+ Treg cells or adoptive transfer of pre-sensitized CD8+, but not CD4+, T cells reversed long-term islet allograft survival induced by treatments with donor MHC DNA vaccination and IL-2 regimen prior to transplantation plus rapamycin treatment post-transplantation.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0008756-g007: Depleting CD25+ Treg cells or adoptive transfer of pre-sensitized CD8+ T cells abrogates long-term islet allograft survival.B6 mice were treated with MHC I + IL-2/anti-IL-2 and subsequent MHC II + IL-2 prior to transplantation, transplanted with Balb/C islets, and treated with low doses of rapamycin post-transplantation (A + B + Rapa). They were also treated with either depleting anti-CD25 Ab (A + B + Rapa + Anti-CD25) (□, n = 6) or control IgG (A + B + Rapa + Control IgG) (ν, n = 7), or received upon transplantation syngeneic CD8+CD25− (A + B + Rapa + CD8) (○, n = 7) or CD4+CD25− T cells (A + B + Rapa + CD4) (▵, n = 6) that were isolated from B6 mice pre-sensitized i.p. with irradiated Balb/C splenocytes two weeks earlier. Depleting CD25+ Treg cells or adoptive transfer of pre-sensitized CD8+, but not CD4+, T cells reversed long-term islet allograft survival induced by treatments with donor MHC DNA vaccination and IL-2 regimen prior to transplantation plus rapamycin treatment post-transplantation.
Mentions: Since donor MHC DNA vaccination and IL-2 regimen prior to transplantation induced Treg cells and promoted long-term allograft survival, we then asked whether this long-term allograft survival is dependent on Treg cells. The immunized B6 mice that also received IL-2 regimen prior to transplantation, as described in Methods section, were transplanted with Balb/C islets and treated with low dose of rapamycin as well as depleting anti-CD25 Ab or isotype control. As shown in Figure 7, we found that depleting CD25+ Treg cells abrogated the long-term islet allograft survival induced by MHC DNA vaccination plus IL-2 regimen pre-transplantation and the rapamycin treatment post-transplantation (MST = 25 days). Moreover, this long-term allograft survival could not be achieved at all in IL-2-deficient mice that lack CD25+ T cells (data not shown). On the other hand, the long-term allograft survival induced by this protocol was also reversed by the adoptive transfer of CD8+CD25− T cells that were isolated from mice that were sensitized i.p. with Balb/C splenocytes two weeks prior to the cell transfer (MST = 31 days). However, transfer of pre-sensitized CD4+CD25− counterparts did not significantly shorten allograft survival (MST = 92 vs. 102 days, P>0.05). These findings suggest that long-term allograft survival, induced by rapamycin post-transplantation and donor MHC DNA vaccination plus IL-2 regimen pre-transplantation, is dependent on CD25+ Treg cells and that adoptive transfer of allo-sensitized CD8+, but not CD4+, T cells prevents this long-term allograft survival.

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