in vitro blocking of PD-L1/CD80 (B7-1) interactions
Mott, K. R., et al (2014). "Inclusion of CD80 in HSV targets the recombinant virus to PD-L1 on DCs and allows productive infection and robust immune responses" PLoS One 9(1): e87617. PubMed
CD80 plays a critical role in stimulation of T cells and subsequent control of infection. To investigate the effect of CD80 on HSV-1 infection, we constructed a recombinant HSV-1 virus that expresses two copies of the CD80 gene in place of the latency associated transcript (LAT). This mutant virus (HSV-CD80) expressed high levels of CD80 and had similar virus replication kinetics as control viruses in rabbit skin cells. In contrast to parental virus, this CD80 expressing recombinant virus replicated efficiently in immature dendritic cells (DCs). Additionally, the susceptibility of immature DCs to HSV-CD80 infection was mediated by CD80 binding to PD-L1 on DCs. This interaction also contributed to a significant increase in T cell activation. Taken together, these results suggest that inclusion of CD80 as a vaccine adjuvant may promote increased vaccine efficacy by enhancing the immune response directly and also indirectly by targeting to DC.
in vivo blocking of PD-L1/CD80 (B7-1) interactions
Paterson, A. M., et al (2011). "The programmed death-1 ligand 1:B7-1 pathway restrains diabetogenic effector T cells in vivo" J Immunol 187(3): 1097-1105. PubMed
Programmed death-1 ligand 1 (PD-L1) is a coinhibitory molecule that negatively regulates multiple tolerance checkpoints. In the NOD mouse model, PD-L1 regulates the development of diabetes. PD-L1 has two binding partners, programmed death-1 and B7-1, but the significance of the PD-L1:B7-1 interaction in regulating self-reactive T cell responses is not yet clear. To investigate this issue in NOD mice, we have compared the effects of two anti-PD-L1 Abs that have different blocking activities. Anti-PD-L1 mAb 10F.2H11 sterically and functionally blocks only PD-L1:B7-1 interactions, whereas anti-PD-L1 mAb 10F.9G2 blocks both PD-L1:B7-1 and PD-L1:programmed death-1 interactions. Both Abs had potent, yet distinct effects in accelerating diabetes in NOD mice: the single-blocker 10F.2H11 mAb was more effective at precipitating diabetes in older (13-wk-old) than in younger (6- to 7-wk-old) mice, whereas the dual-blocker 10F.9G2 mAb rapidly induced diabetes in NOD mice of both ages. Similarly, 10F.2H11 accelerated diabetes in recipients of T cells from diabetic, but not prediabetic mice, whereas 10F.9G2 was effective in both settings. Both anti-PD-L1 mAbs precipitated diabetes in adoptive transfer models of CD4(+) and CD8(+) T cell-driven diabetes. Taken together, these data demonstrate that the PD-L1:B7-1 pathway inhibits potentially pathogenic self-reactive effector CD4(+) and CD8(+) T cell responses in vivo, and suggest that the immunoinhibitory functions of this pathway may be particularly important during the later phases of diabetogenesis.
in vivo blocking of PD-L1/CD80 (B7-1) interactions
Yang, J., et al (2011). "The novel costimulatory programmed death ligand 1/B7.1 pathway is functional in inhibiting alloimmune responses in vivo" J Immunol 187(3): 1113-1119. PubMed
The programmed death ligand 1 (PDL1)/programmed death 1 (PD1) costimulatory pathway plays an important role in the inhibition of alloimmune responses as well as in the induction and maintenance of peripheral tolerance. It has been demonstrated recently that PDL1 also can bind B7.1 to inhibit T cell responses in vitro. Using the bm12 into B6 heart transplant model, we investigated the functional significance of this interaction in alloimmune responses in vivo. PD1 blockade unlike PDL1 blockade failed to accelerate bm12 allograft rejection, suggesting a role for an additional binding partner for PDL1 other than PD1 in transplant rejection. PDL1 blockade was able to accelerate allograft rejection in B7.2-deficient recipients but not B7.1-deficient recipients, indicating that PDL1 interaction with B7.1 was important in inhibiting rejection. Administration of the novel 2H11 anti-PDL1 mAb, which only blocks the PDL1-B7.1 interaction, aggravated chronic injury of bm12 allografts in B6 recipients. Aggravated chronic injury was associated with an increased frequency of alloreactive IFN-gamma-, IL-4-, and IL-6-producing splenocytes and a decreased percentage of regulatory T cells in the recipients. Using an in vitro cell culture assay, blockade of the interaction of PDL1 on dendritic cells with B7.1 on T cells increased IFN-gamma production from alloreactive CD4(+) T cells, whereas blockade of dendritic cell B7.1 interaction with T cell PDL1 did not. These data indicate that PDL1 interaction with B7.1 plays an important role in the inhibition of alloimmune responses in vivo and suggests a dominant direction for PDL1 and B7.1 interaction.
