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Inhibition of Donor-Reactive CD8+ T Cell Responses by Selective CD28 Blockade Is Independent of Reduced ICOS Expression.

Liu D, Suchard SJ, Nadler SG, Ford ML - PLoS ONE (2015)

Bottom Line: We previously showed that selective CD28 blockade with novel domain antibodies that leave CTLA-4-mediated coinhibitory signaling intact resulted in more profound attenuation of donor-reactive T cell responses and improved graft survival in a murine transplant model.Selective CD28 blockade was also associated with decreased ICOS expression on donor-reactive CD8+ T cell responses as compared to CTLA-4 Ig, but the functional importance of this reduced ICOS expression was not known.In this study, we created retrogenic donor-reactive CD8+ T cells that overexpress ICOS in order to determine whether reduced ICOS expression mechanistically underlies the increased efficacy of selective CD28 blockade in controlling graft-specific T cell responses as compared to conventional costimulation blockade with CTLA-4 Ig.

View Article: PubMed Central - PubMed

Affiliation: Emory Transplant Center and Department of Surgery, Emory University, Atlanta, GA 30322, United States of America.

ABSTRACT
Programmed T cell differentiation is critically influenced by the complement of costimulatory and coinhibitory signals transmitted during initial antigen encounter. We previously showed that selective CD28 blockade with novel domain antibodies that leave CTLA-4-mediated coinhibitory signaling intact resulted in more profound attenuation of donor-reactive T cell responses and improved graft survival in a murine transplant model. Selective CD28 blockade was also associated with decreased ICOS expression on donor-reactive CD8+ T cell responses as compared to CTLA-4 Ig, but the functional importance of this reduced ICOS expression was not known. In this study, we created retrogenic donor-reactive CD8+ T cells that overexpress ICOS in order to determine whether reduced ICOS expression mechanistically underlies the increased efficacy of selective CD28 blockade in controlling graft-specific T cell responses as compared to conventional costimulation blockade with CTLA-4 Ig. Results indicated that the ability of selective CD28 blockade to blunt donor-reactive CD8+ T cell expansion following transplantation was independent of its ability to inhibit ICOS expression. Furthermore, we have previously published that 2B4 coinhibitory signals are functionally important for controlling graft-specific CD8+ T cell responses in mice treated with CD28 blockade. Here we used a co-adoptive transfer approach to determine that 2B4 coinhibitory signals on antigen-specific CD8+ T cells function in a cell-intrinsic manner to limit ICOS expression in the setting of selective CD28 blockade.

No MeSH data available.


Related in: MedlinePlus

Reduced ICOS expression following selective CD28 blockade is CTLA-4 dependent.Naïve B6 animals were adoptively transferred with 106 congenically labeled Thy1.1+ CD8+ OT-I T cells and 106 Thy1.1+ CD4+ OT-II T cells and then challenged with an OVA-expressing skin graft. Mice remained untreated or were treated with CTLA-4 Ig, anti-CD28 dAb, or anti-CD28 dAb + anti-CTLA-4. Animals were sacrificed on day 10 post-transplant and draining LN cells were analyzed by flow cytometry. A, ICOS expression on antigen-specific Thy1.1+ CD4+ and CD8+ T cells on day 10 post-transplant. B, Summary data from multiple animals n = 5-8/group. C, Antigen-specific Thy1.1+ CD8+ T cells analyzed on day 10 post-transplant were gated on ICOS+ vs. ICOS- cells, and results show CD44 expression (MFI) in these two subsets in the indicated treatment groups (n = 5-8/group). *p<0.05.
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pone.0130490.g001: Reduced ICOS expression following selective CD28 blockade is CTLA-4 dependent.Naïve B6 animals were adoptively transferred with 106 congenically labeled Thy1.1+ CD8+ OT-I T cells and 106 Thy1.1+ CD4+ OT-II T cells and then challenged with an OVA-expressing skin graft. Mice remained untreated or were treated with CTLA-4 Ig, anti-CD28 dAb, or anti-CD28 dAb + anti-CTLA-4. Animals were sacrificed on day 10 post-transplant and draining LN cells were analyzed by flow cytometry. A, ICOS expression on antigen-specific Thy1.1+ CD4+ and CD8+ T cells on day 10 post-transplant. B, Summary data from multiple animals n = 5-8/group. C, Antigen-specific Thy1.1+ CD8+ T cells analyzed on day 10 post-transplant were gated on ICOS+ vs. ICOS- cells, and results show CD44 expression (MFI) in these two subsets in the indicated treatment groups (n = 5-8/group). *p<0.05.

Mentions: In order to determine the mechanisms underlying the observed reduced ICOS expression following selective CD28 blockade as compared to CTLA-4 Ig [15], we interrogated the requirement for preserved CTLA-4 coinhibitory signals in mediating this effect. Naïve B6 animals were adoptively transferred with 106 congenically labeled Thy1.1+ CD8+ OT-I T cells and 106 Thy1.1+ CD4+ OT-II T cells and then challenged with an OVA-expressing skin graft. Mice remained untreated or were treated with CTLA-4 Ig, anti-CD28 dAb, or anti-CD28 dAb + anti-CTLA-4 as described in the materials and methods. Animals were sacrificed on day 10 post-transplant and draining LN cells were analyzed by flow cytometry. Results showed that, as expected, ICOS was upregulated on the majority of antigen-specific CD4+ and CD8+ T cells by day 10 post-transplant (Fig 1A). As we reported previously, treatment with CTLA-4 Ig resulted in decreased ICOS expression on antigen-specific cells in both the CD4+ and CD8+ T cell compartments, but animals treated with anti-CD28 dAb experienced an even more profound reduction in ICOS expression (Fig 1B). Within each treatment group, antigen-specific CD8+ cells that were ICOS+ exhibited increased CD44 expression as compared to those that were ICOS-, indicating that under all conditions decreased ICOS expression correlated with reduced activation (Fig 1C).


Inhibition of Donor-Reactive CD8+ T Cell Responses by Selective CD28 Blockade Is Independent of Reduced ICOS Expression.

Liu D, Suchard SJ, Nadler SG, Ford ML - PLoS ONE (2015)

Reduced ICOS expression following selective CD28 blockade is CTLA-4 dependent.Naïve B6 animals were adoptively transferred with 106 congenically labeled Thy1.1+ CD8+ OT-I T cells and 106 Thy1.1+ CD4+ OT-II T cells and then challenged with an OVA-expressing skin graft. Mice remained untreated or were treated with CTLA-4 Ig, anti-CD28 dAb, or anti-CD28 dAb + anti-CTLA-4. Animals were sacrificed on day 10 post-transplant and draining LN cells were analyzed by flow cytometry. A, ICOS expression on antigen-specific Thy1.1+ CD4+ and CD8+ T cells on day 10 post-transplant. B, Summary data from multiple animals n = 5-8/group. C, Antigen-specific Thy1.1+ CD8+ T cells analyzed on day 10 post-transplant were gated on ICOS+ vs. ICOS- cells, and results show CD44 expression (MFI) in these two subsets in the indicated treatment groups (n = 5-8/group). *p<0.05.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4476729&req=5

pone.0130490.g001: Reduced ICOS expression following selective CD28 blockade is CTLA-4 dependent.Naïve B6 animals were adoptively transferred with 106 congenically labeled Thy1.1+ CD8+ OT-I T cells and 106 Thy1.1+ CD4+ OT-II T cells and then challenged with an OVA-expressing skin graft. Mice remained untreated or were treated with CTLA-4 Ig, anti-CD28 dAb, or anti-CD28 dAb + anti-CTLA-4. Animals were sacrificed on day 10 post-transplant and draining LN cells were analyzed by flow cytometry. A, ICOS expression on antigen-specific Thy1.1+ CD4+ and CD8+ T cells on day 10 post-transplant. B, Summary data from multiple animals n = 5-8/group. C, Antigen-specific Thy1.1+ CD8+ T cells analyzed on day 10 post-transplant were gated on ICOS+ vs. ICOS- cells, and results show CD44 expression (MFI) in these two subsets in the indicated treatment groups (n = 5-8/group). *p<0.05.
Mentions: In order to determine the mechanisms underlying the observed reduced ICOS expression following selective CD28 blockade as compared to CTLA-4 Ig [15], we interrogated the requirement for preserved CTLA-4 coinhibitory signals in mediating this effect. Naïve B6 animals were adoptively transferred with 106 congenically labeled Thy1.1+ CD8+ OT-I T cells and 106 Thy1.1+ CD4+ OT-II T cells and then challenged with an OVA-expressing skin graft. Mice remained untreated or were treated with CTLA-4 Ig, anti-CD28 dAb, or anti-CD28 dAb + anti-CTLA-4 as described in the materials and methods. Animals were sacrificed on day 10 post-transplant and draining LN cells were analyzed by flow cytometry. Results showed that, as expected, ICOS was upregulated on the majority of antigen-specific CD4+ and CD8+ T cells by day 10 post-transplant (Fig 1A). As we reported previously, treatment with CTLA-4 Ig resulted in decreased ICOS expression on antigen-specific cells in both the CD4+ and CD8+ T cell compartments, but animals treated with anti-CD28 dAb experienced an even more profound reduction in ICOS expression (Fig 1B). Within each treatment group, antigen-specific CD8+ cells that were ICOS+ exhibited increased CD44 expression as compared to those that were ICOS-, indicating that under all conditions decreased ICOS expression correlated with reduced activation (Fig 1C).

Bottom Line: We previously showed that selective CD28 blockade with novel domain antibodies that leave CTLA-4-mediated coinhibitory signaling intact resulted in more profound attenuation of donor-reactive T cell responses and improved graft survival in a murine transplant model.Selective CD28 blockade was also associated with decreased ICOS expression on donor-reactive CD8+ T cell responses as compared to CTLA-4 Ig, but the functional importance of this reduced ICOS expression was not known.In this study, we created retrogenic donor-reactive CD8+ T cells that overexpress ICOS in order to determine whether reduced ICOS expression mechanistically underlies the increased efficacy of selective CD28 blockade in controlling graft-specific T cell responses as compared to conventional costimulation blockade with CTLA-4 Ig.

View Article: PubMed Central - PubMed

Affiliation: Emory Transplant Center and Department of Surgery, Emory University, Atlanta, GA 30322, United States of America.

ABSTRACT
Programmed T cell differentiation is critically influenced by the complement of costimulatory and coinhibitory signals transmitted during initial antigen encounter. We previously showed that selective CD28 blockade with novel domain antibodies that leave CTLA-4-mediated coinhibitory signaling intact resulted in more profound attenuation of donor-reactive T cell responses and improved graft survival in a murine transplant model. Selective CD28 blockade was also associated with decreased ICOS expression on donor-reactive CD8+ T cell responses as compared to CTLA-4 Ig, but the functional importance of this reduced ICOS expression was not known. In this study, we created retrogenic donor-reactive CD8+ T cells that overexpress ICOS in order to determine whether reduced ICOS expression mechanistically underlies the increased efficacy of selective CD28 blockade in controlling graft-specific T cell responses as compared to conventional costimulation blockade with CTLA-4 Ig. Results indicated that the ability of selective CD28 blockade to blunt donor-reactive CD8+ T cell expansion following transplantation was independent of its ability to inhibit ICOS expression. Furthermore, we have previously published that 2B4 coinhibitory signals are functionally important for controlling graft-specific CD8+ T cell responses in mice treated with CD28 blockade. Here we used a co-adoptive transfer approach to determine that 2B4 coinhibitory signals on antigen-specific CD8+ T cells function in a cell-intrinsic manner to limit ICOS expression in the setting of selective CD28 blockade.

No MeSH data available.


Related in: MedlinePlus