Limits...
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.

Show MeSH

Related in: MedlinePlus

PD-L1-mediated costimulation occurs independently of known CD80 or PD-1 interactions.Representative dot-plots (A) and total cell numbers (B) of the OVA257–264/Kb-specific splenic CD8 T cell response eight days after LM infection from mice treated with IgG isotype control, anti-PD-L1 (10F.9G2), or with an mAb that blocks PD-L1 interaction with CD80 (43H12), or with anti-PD-1 (RMP1-14). C, Total numbers of OVA257–264/Kb-specific splenic CD8 T cells eight days after LM infection from mice treated with IgG isotype control, anti-PD-1 (RMP1-14), anti-PD-L1 (10F.9G2), both anti-PD-L1(10F.9G2) and PD1(RMP1-14), both anti PD-1(RMP1-14) and 43H12 or both anti-PD-1(RMP1-14) and anti-CD80 (1G10). Data are representative of three independent experiments with five mice per group. Data were analyzed by two-way ANOVA, (*p<0.05, **p<0.01, ***p<0.001, n.s., not significant).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3569435&req=5

pone-0056539-g008: PD-L1-mediated costimulation occurs independently of known CD80 or PD-1 interactions.Representative dot-plots (A) and total cell numbers (B) of the OVA257–264/Kb-specific splenic CD8 T cell response eight days after LM infection from mice treated with IgG isotype control, anti-PD-L1 (10F.9G2), or with an mAb that blocks PD-L1 interaction with CD80 (43H12), or with anti-PD-1 (RMP1-14). C, Total numbers of OVA257–264/Kb-specific splenic CD8 T cells eight days after LM infection from mice treated with IgG isotype control, anti-PD-1 (RMP1-14), anti-PD-L1 (10F.9G2), both anti-PD-L1(10F.9G2) and PD1(RMP1-14), both anti PD-1(RMP1-14) and 43H12 or both anti-PD-1(RMP1-14) and anti-CD80 (1G10). Data are representative of three independent experiments with five mice per group. Data were analyzed by two-way ANOVA, (*p<0.05, **p<0.01, ***p<0.001, n.s., not significant).

Mentions: The two known counter-receptors of PD-L1 are PD-1 and CD80, both of which are well documented to transduce negative regulatory signals during T cell activation [4], [7]. To scrutinize through which ligand PD-L1 mediated costimulation, we took advantage of mAbs that specifically block PD-L1 binding to PD-1 (RMP1-14; [16]) or to CD80 (43H12); [7]) and compared their ability to block the CD8 T cell response during LM infection with the general inhibition of PD-L1 by 10F.9G2. Surprisingly, treatment with either RMP1-14 or 43H12 failed to inhibit the response unlike 10F.9G2 treatment (Fig. 8A,B,C). As an important positive control, we confirmed the blocking efficiency of 43H12 in a previously described T cell tolerance model [7]. Treatment with 43H12 greatly enhanced the CD8 T cell response in this model (data not shown). In addition, the consistent increase in the CD4 T cell response (data not shown) and enhanced LM clearance (Fig. 5) with RMP1-14 treatment, indicated that this mAb was also operating. To insure that the lack of inhibition of the CD8 T cell response by PD-L1-CD80 blockade (43H12) or PD-1 blockade (RMP1-14) was not due to compensation through CD80 or PD-1, we blocked both interactions simultaneously, and found no inhibition (Fig. 8B). This result was also confirmed by blocking CD80 with 1G10 (Fig. 8B), which has been shown to block CD80:PD-1 interaction in vitro[8]. In this experiment, anti-PD-1 treatment resulted in an increase in antigen-specific CD8 T cells (Fig. 8B), but this was not a consistent finding. Further, to exclude the possibility that the reduced antigen-specific CD8 T cell response was caused by a potentiated inhibitory effect via enhancing PD-L1:PD-1 interaction due to 10F.9G2 mAb treatment, we blocked PD-1 in conjunction with 10F.9G2 treatment which again demonstrated that 10F.9G2 blockade of PD-L1 reduced the antigen-specific CD8 T cell response (Fig. 8B). Taken together, these data suggested that PD-L1 costimulation was mediated either by binding to an epitope on CD80 or PD-1 that was not blocked by the available mAbs or by interaction with a third unknown binding partner.


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-mediated costimulation occurs independently of known CD80 or PD-1 interactions.Representative dot-plots (A) and total cell numbers (B) of the OVA257–264/Kb-specific splenic CD8 T cell response eight days after LM infection from mice treated with IgG isotype control, anti-PD-L1 (10F.9G2), or with an mAb that blocks PD-L1 interaction with CD80 (43H12), or with anti-PD-1 (RMP1-14). C, Total numbers of OVA257–264/Kb-specific splenic CD8 T cells eight days after LM infection from mice treated with IgG isotype control, anti-PD-1 (RMP1-14), anti-PD-L1 (10F.9G2), both anti-PD-L1(10F.9G2) and PD1(RMP1-14), both anti PD-1(RMP1-14) and 43H12 or both anti-PD-1(RMP1-14) and anti-CD80 (1G10). Data are representative of three independent experiments with five mice per group. Data were analyzed by two-way ANOVA, (*p<0.05, **p<0.01, ***p<0.001, n.s., not significant).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3569435&req=5

pone-0056539-g008: PD-L1-mediated costimulation occurs independently of known CD80 or PD-1 interactions.Representative dot-plots (A) and total cell numbers (B) of the OVA257–264/Kb-specific splenic CD8 T cell response eight days after LM infection from mice treated with IgG isotype control, anti-PD-L1 (10F.9G2), or with an mAb that blocks PD-L1 interaction with CD80 (43H12), or with anti-PD-1 (RMP1-14). C, Total numbers of OVA257–264/Kb-specific splenic CD8 T cells eight days after LM infection from mice treated with IgG isotype control, anti-PD-1 (RMP1-14), anti-PD-L1 (10F.9G2), both anti-PD-L1(10F.9G2) and PD1(RMP1-14), both anti PD-1(RMP1-14) and 43H12 or both anti-PD-1(RMP1-14) and anti-CD80 (1G10). Data are representative of three independent experiments with five mice per group. Data were analyzed by two-way ANOVA, (*p<0.05, **p<0.01, ***p<0.001, n.s., not significant).
Mentions: The two known counter-receptors of PD-L1 are PD-1 and CD80, both of which are well documented to transduce negative regulatory signals during T cell activation [4], [7]. To scrutinize through which ligand PD-L1 mediated costimulation, we took advantage of mAbs that specifically block PD-L1 binding to PD-1 (RMP1-14; [16]) or to CD80 (43H12); [7]) and compared their ability to block the CD8 T cell response during LM infection with the general inhibition of PD-L1 by 10F.9G2. Surprisingly, treatment with either RMP1-14 or 43H12 failed to inhibit the response unlike 10F.9G2 treatment (Fig. 8A,B,C). As an important positive control, we confirmed the blocking efficiency of 43H12 in a previously described T cell tolerance model [7]. Treatment with 43H12 greatly enhanced the CD8 T cell response in this model (data not shown). In addition, the consistent increase in the CD4 T cell response (data not shown) and enhanced LM clearance (Fig. 5) with RMP1-14 treatment, indicated that this mAb was also operating. To insure that the lack of inhibition of the CD8 T cell response by PD-L1-CD80 blockade (43H12) or PD-1 blockade (RMP1-14) was not due to compensation through CD80 or PD-1, we blocked both interactions simultaneously, and found no inhibition (Fig. 8B). This result was also confirmed by blocking CD80 with 1G10 (Fig. 8B), which has been shown to block CD80:PD-1 interaction in vitro[8]. In this experiment, anti-PD-1 treatment resulted in an increase in antigen-specific CD8 T cells (Fig. 8B), but this was not a consistent finding. Further, to exclude the possibility that the reduced antigen-specific CD8 T cell response was caused by a potentiated inhibitory effect via enhancing PD-L1:PD-1 interaction due to 10F.9G2 mAb treatment, we blocked PD-1 in conjunction with 10F.9G2 treatment which again demonstrated that 10F.9G2 blockade of PD-L1 reduced the antigen-specific CD8 T cell response (Fig. 8B). Taken together, these data suggested that PD-L1 costimulation was mediated either by binding to an epitope on CD80 or PD-1 that was not blocked by the available mAbs or by interaction with a third unknown binding partner.

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