Specific and high-affinity binding of tetramerized PD-L1 extracellular domain to PD-1-expressing cells: possible application to enhance T cell function

Abstract

The negative co-stimulatory receptor, programmed cell death 1 (PD-1), is induced on activated T cells and delivers inhibitory signals upon engagement with its ligands PD-L1 and PD-L2, which are expressed on various somatic cells and certain cancers. Accumulating evidence suggests that interfering with the PD-1-PD-L1 interaction may result in the restoration of defective T cell functions in cancer and chronic viral infection. Herein, we established procedures to produce large amounts of renatured recombinant extracellular domain proteins of mouse PD-1 (mPD-1) and PD-L1. While monomeric mPD-1 and mouse PD-L1 (mPD-L1) only marginally interacted with the cells expressing their counterpart proteins, their tetramerization markedly enhanced the affinity with the K(d) of mPD-L1 tetramer being nearly 100-fold lower than that of the corresponding monomer. The affinity of mPD-L1 tetramer was even higher than a high-affinity anti-PD-1 mAb, and it efficiently inhibited the binding of mPD-L1/Fc-chimeric protein to mPD-1(+) cells. Functionally, mPD-L1 tetramer significantly enhanced the proliferative responses as well as the cytotoxic activity of T cells against specific target cells in vitro. The results suggest that oligomeric PD-L1 extracellular domains may provide a potential means to restore T cell functions in cancer and viral infection in humans.

Magneto-nanosensor platform for probing low-affinity protein–protein interactions and identification of a low-affinity PD-L1/PD-L2 interaction

“…3 ). Under similar conditions, baseline shifts or stepwise changes would be easily observed in SPR signals 14 31 . Importantly, when the same concentrations of protein A-coated MNPs were flowed into two identical channels where murine IgG isotypes were immobilized, the binding curves from the channels were highly reproducible ( Supplementary Fig.…”

Expression and function of PD‐1 in human γδ T cells that recognize phosphoantigens

“…Since a high level of PD‐L1/PD‐L2 expression was observed on malignant tumors in patients 34, strong signaling via PD‐1/PD‐L1 engagement could negatively modulate the γδ TCR‐mediated signaling. Even if this is the case, the abrogation of PD‐1/PD‐Ls engagement by specific mAbs or recombinant proteins 29 may lead to the promotion of anti‐tumor activity because PD‐1 on highly activated γδ T cells is functional.…”

“…PD‐1 ligands are expressed on DC as well as various tissue cells, and as such the PD‐1/PD‐Ls system plays a crucial role in the maintenance of self‐tolerance and prevention of potential autoimmunity 25–27. Moreover, we and others have previously reported that the specific cytotoxic activity of αβ T cells against tumor cells expressing PD‐L1 was attenuated in several murine model systems 28–30. Accumulating evidence indicates that significant proportions of human tumor cells of various types express PD‐Ls 31–33; more recently, we have reported that the expression of PD‐L1 in ovarian tumors is a predictive factor for poor prognosis among human ovarian cancer patients 34.…”

LncRNA SNHG1 regulates immune escape of renal cell carcinoma by targeting miR‐129‐3p to activate STAT3 and PD‐L1

“…Immune escape is a process wherein tumour cells can evade the immune system through different mechanisms to promote their migration and proliferation (Jiang et al, 2019). Programmed death 1 (PD‐1) and its ligand PD‐L1 play important roles in the maintenance of immune homeostasis (Terawaki et al, 2007). Overexpressed PD‐L1 on the surface of tumour cells interacts with overexpressed PD‐1 in T cells and can prohibit the activation, proliferation, and secretion of cytokines by T lymphocytes (Ni et al, 2001).…”