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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

Efficacy of selective CD28 blockade in controlling donor-reactive CD8+ T cell expansion is independent of its ability to inhibit ICOS expression.Naïve B6 animals were adoptively transferred with 106 congenically labeled ICOSrg Thy1.1+ OT-I T cells (or pMY Thy1.1+ OT-I controls) along with 106 Thy1.1+ CD4+ WT OT-II T cells and then challenged with an OVA-expressing skin graft. Groups of animals were left untreated or treated with anti-CD28 dAb. Animals were sacrificed at day 10 post transplant, and graft-draining LN T cells were analyzed for the expression of the magnitude of the CD8+ Thy1.1+ response. A, Representative flow cytometry plots depicting frequencies of CD44hi Thy1.1+ CD8+ T cells in the treatment groups indicated. B, Summary data of the frequencies of CD44hi Thy1.1+ CD8+ T cells (three independent experiments with a total of n = 6–9 animals/group). C, Summary data of the absolute numbers of CD44hi Thy1.1+ CD8+ T cells (three independent experiments with a total of n = 6–9 animals/group). D, Summary data of the frequencies of CD44hi Thy1.1+ CD4+ T cells (three independent experiments with a total of n = 6–9 animals/group). C, Summary data of the absolute numbers of CD44hi Thy1.1+ CD4+ T cells (three independent experiments with a total of n = 6–9 animals/group). *p<0.05, **p<0.01.
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pone.0130490.g003: Efficacy of selective CD28 blockade in controlling donor-reactive CD8+ T cell expansion is independent of its ability to inhibit ICOS expression.Naïve B6 animals were adoptively transferred with 106 congenically labeled ICOSrg Thy1.1+ OT-I T cells (or pMY Thy1.1+ OT-I controls) along with 106 Thy1.1+ CD4+ WT OT-II T cells and then challenged with an OVA-expressing skin graft. Groups of animals were left untreated or treated with anti-CD28 dAb. Animals were sacrificed at day 10 post transplant, and graft-draining LN T cells were analyzed for the expression of the magnitude of the CD8+ Thy1.1+ response. A, Representative flow cytometry plots depicting frequencies of CD44hi Thy1.1+ CD8+ T cells in the treatment groups indicated. B, Summary data of the frequencies of CD44hi Thy1.1+ CD8+ T cells (three independent experiments with a total of n = 6–9 animals/group). C, Summary data of the absolute numbers of CD44hi Thy1.1+ CD8+ T cells (three independent experiments with a total of n = 6–9 animals/group). D, Summary data of the frequencies of CD44hi Thy1.1+ CD4+ T cells (three independent experiments with a total of n = 6–9 animals/group). C, Summary data of the absolute numbers of CD44hi Thy1.1+ CD4+ T cells (three independent experiments with a total of n = 6–9 animals/group). *p<0.05, **p<0.01.

Mentions: To determine the impact of constitutive ICOS expression on the efficacy of selective CD28 blockade, groups of animals were left untreated or treated with anti-CD28 dAb. Animals were sacrificed at day 10 post transplant, and splenic and graft-draining LN T cells were analyzed for the expression of the magnitude of the CD8+ Thy1.1+ response. Results revealed a detectable population of CD44hi Thy1.1+ CD8+ T cells in recipients of pMY cells (Fig 3A). Interestingly, constitutive ICOS overexpression did not impact the magnitude of donor-reactive CD8+ T cell expansion in the absence of immune modulation (Fig 3B and 3C). As expected, anti-CD28 dAb treatment of recipients of pMY OT-I T cells resulted in a marked inhibition of the antigen-specific CD8+ T cell response (Fig 3A–3C). Strikingly, however, ICOSrg graft-specific CD8+ T cells were similarly profoundly inhibited following selective CD28 blockade. The constitutive overexpression of ICOS on donor-reactive CD8+ T cells also did not alter the donor-reactive CD4+ T cell response, either in the presence or absence of selective CD28 blockade (Fig 3D and 3E). Overall, these results indicate that reduced ICOS expression is not the mechanism by which selective CD28 blockade more potently inhibits the expansion of donor-reactive CD8+ T cells following transplantation.


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)

Efficacy of selective CD28 blockade in controlling donor-reactive CD8+ T cell expansion is independent of its ability to inhibit ICOS expression.Naïve B6 animals were adoptively transferred with 106 congenically labeled ICOSrg Thy1.1+ OT-I T cells (or pMY Thy1.1+ OT-I controls) along with 106 Thy1.1+ CD4+ WT OT-II T cells and then challenged with an OVA-expressing skin graft. Groups of animals were left untreated or treated with anti-CD28 dAb. Animals were sacrificed at day 10 post transplant, and graft-draining LN T cells were analyzed for the expression of the magnitude of the CD8+ Thy1.1+ response. A, Representative flow cytometry plots depicting frequencies of CD44hi Thy1.1+ CD8+ T cells in the treatment groups indicated. B, Summary data of the frequencies of CD44hi Thy1.1+ CD8+ T cells (three independent experiments with a total of n = 6–9 animals/group). C, Summary data of the absolute numbers of CD44hi Thy1.1+ CD8+ T cells (three independent experiments with a total of n = 6–9 animals/group). D, Summary data of the frequencies of CD44hi Thy1.1+ CD4+ T cells (three independent experiments with a total of n = 6–9 animals/group). C, Summary data of the absolute numbers of CD44hi Thy1.1+ CD4+ T cells (three independent experiments with a total of n = 6–9 animals/group). *p<0.05, **p<0.01.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4476729&req=5

pone.0130490.g003: Efficacy of selective CD28 blockade in controlling donor-reactive CD8+ T cell expansion is independent of its ability to inhibit ICOS expression.Naïve B6 animals were adoptively transferred with 106 congenically labeled ICOSrg Thy1.1+ OT-I T cells (or pMY Thy1.1+ OT-I controls) along with 106 Thy1.1+ CD4+ WT OT-II T cells and then challenged with an OVA-expressing skin graft. Groups of animals were left untreated or treated with anti-CD28 dAb. Animals were sacrificed at day 10 post transplant, and graft-draining LN T cells were analyzed for the expression of the magnitude of the CD8+ Thy1.1+ response. A, Representative flow cytometry plots depicting frequencies of CD44hi Thy1.1+ CD8+ T cells in the treatment groups indicated. B, Summary data of the frequencies of CD44hi Thy1.1+ CD8+ T cells (three independent experiments with a total of n = 6–9 animals/group). C, Summary data of the absolute numbers of CD44hi Thy1.1+ CD8+ T cells (three independent experiments with a total of n = 6–9 animals/group). D, Summary data of the frequencies of CD44hi Thy1.1+ CD4+ T cells (three independent experiments with a total of n = 6–9 animals/group). C, Summary data of the absolute numbers of CD44hi Thy1.1+ CD4+ T cells (three independent experiments with a total of n = 6–9 animals/group). *p<0.05, **p<0.01.
Mentions: To determine the impact of constitutive ICOS expression on the efficacy of selective CD28 blockade, groups of animals were left untreated or treated with anti-CD28 dAb. Animals were sacrificed at day 10 post transplant, and splenic and graft-draining LN T cells were analyzed for the expression of the magnitude of the CD8+ Thy1.1+ response. Results revealed a detectable population of CD44hi Thy1.1+ CD8+ T cells in recipients of pMY cells (Fig 3A). Interestingly, constitutive ICOS overexpression did not impact the magnitude of donor-reactive CD8+ T cell expansion in the absence of immune modulation (Fig 3B and 3C). As expected, anti-CD28 dAb treatment of recipients of pMY OT-I T cells resulted in a marked inhibition of the antigen-specific CD8+ T cell response (Fig 3A–3C). Strikingly, however, ICOSrg graft-specific CD8+ T cells were similarly profoundly inhibited following selective CD28 blockade. The constitutive overexpression of ICOS on donor-reactive CD8+ T cells also did not alter the donor-reactive CD4+ T cell response, either in the presence or absence of selective CD28 blockade (Fig 3D and 3E). Overall, these results indicate that reduced ICOS expression is not the mechanism by which selective CD28 blockade more potently inhibits the expansion of donor-reactive CD8+ T cells following transplantation.

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