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A potential new pathway for PD-L1 costimulation of the CD8-T cell response to Listeria monocytogenes infection.

Xu D, Fu HH, Obar JJ, Park JJ, Tamada K, Yagita H, Lefrançois L - PLoS ONE (2013)

Bottom Line: However, PD-L1 can also act as a positive costimulator, but the relevant counterreceptor is not known.Simultaneous CD4-T cell depletion and anti-PD-L1 blockade revealed that PD-L1 provided costimulation even in the absence of CD4-T cells.Most importantly, specific blockade of PD-L1 binding to CD80 or to PD-1 did not recapitulate PDL-1 blockade.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, University of Connecticut Health Center, Farmington, Connecticut, United States of America.

ABSTRACT
Programmed death ligand-1 (PD-L1) is an important negative regulator of T cell immune responses via interactions with PD-1 and CD80. However, PD-L1 can also act as a positive costimulator, but the relevant counterreceptor is not known. We analyzed the role of PD-L1 in CD8-T cell responses to infection with Listeria monocytogenes (LM) or vesicular stomatitis virus (VSV). PD-L1 blockade impaired antigen-specific CD8 effector T cell expansion in response to LM, but not to VSV infection, particularly limiting short-lived effector cell differentiation. Simultaneous CD4-T cell depletion and anti-PD-L1 blockade revealed that PD-L1 provided costimulation even in the absence of CD4-T cells. Most importantly, specific blockade of PD-L1 binding to CD80 or to PD-1 did not recapitulate PDL-1 blockade. The results suggested that PD-L1 plays an important costimulatory role for antigen-specific CD8 T cells during LM infection perhaps through a distinct receptor or interaction epitope.

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PD-L1 enhances multifunctional effector CD8 T cell generation.Mice were infected i.v. with 1000 cfu LM-OVA and treated with anti-PD-L1 or control IgG. Eight days later splenocytes were stimulated in vitro with SIINFEKL peptide for 5 hours in the presence of brefeldin A. Production of IL-2, IFNγ and TNF was measured by intracellular staining and flow cytometry. A. The frequency of IFNγ+TNF+IL-2+ antigen-specific CD8+ T cells. B–D. Comparison of the mean fluorescent intensity (MFI) of staining for each cytokine. Values are means +/− standard error. Data are representative of three independent experiments with five mice per group. Data were analyzed by student t test. (*p<0.05, ns, not significant).
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pone-0056539-g003: PD-L1 enhances multifunctional effector CD8 T cell generation.Mice were infected i.v. with 1000 cfu LM-OVA and treated with anti-PD-L1 or control IgG. Eight days later splenocytes were stimulated in vitro with SIINFEKL peptide for 5 hours in the presence of brefeldin A. Production of IL-2, IFNγ and TNF was measured by intracellular staining and flow cytometry. A. The frequency of IFNγ+TNF+IL-2+ antigen-specific CD8+ T cells. B–D. Comparison of the mean fluorescent intensity (MFI) of staining for each cytokine. Values are means +/− standard error. Data are representative of three independent experiments with five mice per group. Data were analyzed by student t test. (*p<0.05, ns, not significant).

Mentions: To test the potential role of the PD-1 axis in the antigen-specific CD8 T cell response, we treated mice with anti-PD-L1 (10F.9G2), anti-PD-L2 (TY25), or anti-PD-1 (RMP1-14) blocking mAb throughout the infection. The pMHCI tetramer-OVA257–264/Kb was used to identify antigen-specific CD8 T cells on day 8 post LM-ova or day 7 post-VSV-ova infections, near the peak of the responses. The VSV-specific CD8 T cell response was not affected by either anti-PD-L1, –PD-L2, or -PD-1 mAbs (Fig. 2A and data not shown). In contrast, blocking PD-L1 resulted in an ∼80% inhibition of the anti-LM CD8 T cell response, while PD-L2 or PD-1 blockade had no effect (Fig. 2B). Interestingly, the LLO190–201/I-Ab-specific CD4-T cell response was not diminished by PD-L1 blockade (Fig. 2C), indicating that a loss of CD4 T cell help could not explain the inhibition of the CD8 T cell response. We also examined the production of cytokines after PD-L1 blockade. While the overall number of cytokine producing cells decreased after PD-L1 blockade, as expected based on the loss of tetramer+ cells, the cells that produced IFNγ, TNF, or IL-2 did so at levels comparable to their normal counterparts (Fig. 3B–D). However, the percentage of polyfunctional antigen-specific CD8 T cells, i.e. those that produced all three cytokines, was reduced by PD-L1 blockade (Fig. 3A). Thus, PD-L1 controlled both the magnitude and the functionality of the CD8 T cell response to LM infection.


A potential new pathway for PD-L1 costimulation of the CD8-T cell response to Listeria monocytogenes infection.

Xu D, Fu HH, Obar JJ, Park JJ, Tamada K, Yagita H, Lefrançois L - PLoS ONE (2013)

PD-L1 enhances multifunctional effector CD8 T cell generation.Mice were infected i.v. with 1000 cfu LM-OVA and treated with anti-PD-L1 or control IgG. Eight days later splenocytes were stimulated in vitro with SIINFEKL peptide for 5 hours in the presence of brefeldin A. Production of IL-2, IFNγ and TNF was measured by intracellular staining and flow cytometry. A. The frequency of IFNγ+TNF+IL-2+ antigen-specific CD8+ T cells. B–D. Comparison of the mean fluorescent intensity (MFI) of staining for each cytokine. Values are means +/− standard error. Data are representative of three independent experiments with five mice per group. Data were analyzed by student t test. (*p<0.05, ns, not significant).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3569435&req=5

pone-0056539-g003: PD-L1 enhances multifunctional effector CD8 T cell generation.Mice were infected i.v. with 1000 cfu LM-OVA and treated with anti-PD-L1 or control IgG. Eight days later splenocytes were stimulated in vitro with SIINFEKL peptide for 5 hours in the presence of brefeldin A. Production of IL-2, IFNγ and TNF was measured by intracellular staining and flow cytometry. A. The frequency of IFNγ+TNF+IL-2+ antigen-specific CD8+ T cells. B–D. Comparison of the mean fluorescent intensity (MFI) of staining for each cytokine. Values are means +/− standard error. Data are representative of three independent experiments with five mice per group. Data were analyzed by student t test. (*p<0.05, ns, not significant).
Mentions: To test the potential role of the PD-1 axis in the antigen-specific CD8 T cell response, we treated mice with anti-PD-L1 (10F.9G2), anti-PD-L2 (TY25), or anti-PD-1 (RMP1-14) blocking mAb throughout the infection. The pMHCI tetramer-OVA257–264/Kb was used to identify antigen-specific CD8 T cells on day 8 post LM-ova or day 7 post-VSV-ova infections, near the peak of the responses. The VSV-specific CD8 T cell response was not affected by either anti-PD-L1, –PD-L2, or -PD-1 mAbs (Fig. 2A and data not shown). In contrast, blocking PD-L1 resulted in an ∼80% inhibition of the anti-LM CD8 T cell response, while PD-L2 or PD-1 blockade had no effect (Fig. 2B). Interestingly, the LLO190–201/I-Ab-specific CD4-T cell response was not diminished by PD-L1 blockade (Fig. 2C), indicating that a loss of CD4 T cell help could not explain the inhibition of the CD8 T cell response. We also examined the production of cytokines after PD-L1 blockade. While the overall number of cytokine producing cells decreased after PD-L1 blockade, as expected based on the loss of tetramer+ cells, the cells that produced IFNγ, TNF, or IL-2 did so at levels comparable to their normal counterparts (Fig. 3B–D). However, the percentage of polyfunctional antigen-specific CD8 T cells, i.e. those that produced all three cytokines, was reduced by PD-L1 blockade (Fig. 3A). Thus, PD-L1 controlled both the magnitude and the functionality of the CD8 T cell response to LM infection.

Bottom Line: However, PD-L1 can also act as a positive costimulator, but the relevant counterreceptor is not known.Simultaneous CD4-T cell depletion and anti-PD-L1 blockade revealed that PD-L1 provided costimulation even in the absence of CD4-T cells.Most importantly, specific blockade of PD-L1 binding to CD80 or to PD-1 did not recapitulate PDL-1 blockade.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, University of Connecticut Health Center, Farmington, Connecticut, United States of America.

ABSTRACT
Programmed death ligand-1 (PD-L1) is an important negative regulator of T cell immune responses via interactions with PD-1 and CD80. However, PD-L1 can also act as a positive costimulator, but the relevant counterreceptor is not known. We analyzed the role of PD-L1 in CD8-T cell responses to infection with Listeria monocytogenes (LM) or vesicular stomatitis virus (VSV). PD-L1 blockade impaired antigen-specific CD8 effector T cell expansion in response to LM, but not to VSV infection, particularly limiting short-lived effector cell differentiation. Simultaneous CD4-T cell depletion and anti-PD-L1 blockade revealed that PD-L1 provided costimulation even in the absence of CD4-T cells. Most importantly, specific blockade of PD-L1 binding to CD80 or to PD-1 did not recapitulate PDL-1 blockade. The results suggested that PD-L1 plays an important costimulatory role for antigen-specific CD8 T cells during LM infection perhaps through a distinct receptor or interaction epitope.

Show MeSH
Related in: MedlinePlus