Inhibition of T-cell-mediated immune response via the PD-1/ PD-L1 axis in cholangiocarcinoma cells

Eur J Pharmacol. 2021 Apr 15:897:173960. doi: 10.1016/j.ejphar.2021.173960. Epub 2021 Feb 19.

Abstract

Cholangiocarcinoma (CCA) is a malignant biliary tract epithelium tumor. The programmed death-1 (PD-1)/programmed receptor-ligand 1 (PD-L1) signaling pathway has been implicated as an immune escape mechanism in several cancers. The present study aimed to assess the expression of PD-L1 on human CCA cell lines and its potential role in suppressing CD8+ T- cell function. A panel of intrahepatic CCA cell lines was evaluated for immune regulatory checkpoint ligands and inflammation markers. Effects of pro-inflammatory cytokine, interferon gamma (IFN-γ), on the expression of immune regulatory checkpoint ligands and inflammation markers were determined. The PD-L1 function was measured by co-culturing CCA cells with lymphocytes. Most of the selected Thai CCA cell lines, including HuCCA-1, RMCCA-1, KKU-100, and KKU-213, expressed higher PD-L1 than normal cholangiocyte MMNK-1 and ANK-1 cells. Both PD-L1 and cyclooxygenase-2 (COX-2) expressions were highest in HuCCA-1 cells. A 48 h treatment with IFN-γ increased the expression of PD-L1 and COX-2 in CCA cells. The expression of CTLA-4 ligands, including H7-1 and H7-2, did not change after IFN-γ treatment. Rofecoxib, a specific COX-2 inhibitor, mitigated IFN-γ-induced PD-L1 expression. After 48 h co-incubation, CD8+ T-cell apoptosis was increased as compared to the control group. Pretreatment of CCA cells with IFN-γ further increased CD8+ T-cell apoptosis. Pembrolizumab, an anti-PD-1 antibody, mitigated CCA cell escape phenomenon. The inhibition of T-cell-mediated immune response via the PD-L1/PD-1 axis are evidenced in intrahepatic CCA. Immunotherapy with checkpoint inhibitor offers a potentially therapeutic strategy for CCA patients; however, further in vivo and clinical studies are required.

Keywords: COX-2; Cholangiocarcinoma; Immune checkpoint; PD-1; PD-L1; Pembrolizumab.

MeSH terms

  • Adult
  • Aged
  • Antibodies, Monoclonal, Humanized / pharmacology*
  • Apoptosis / drug effects
  • B7-H1 Antigen / metabolism*
  • Bile Duct Neoplasms / drug therapy*
  • Bile Duct Neoplasms / immunology
  • Bile Duct Neoplasms / metabolism
  • Bile Duct Neoplasms / pathology
  • CD8-Positive T-Lymphocytes / drug effects*
  • CD8-Positive T-Lymphocytes / immunology
  • CD8-Positive T-Lymphocytes / metabolism
  • Cell Line, Tumor
  • Child
  • Cholangiocarcinoma / drug therapy*
  • Cholangiocarcinoma / immunology
  • Cholangiocarcinoma / metabolism
  • Cholangiocarcinoma / pathology
  • Cyclooxygenase 2 / metabolism
  • Cyclooxygenase 2 Inhibitors / pharmacology
  • Female
  • Humans
  • Immune Checkpoint Inhibitors / pharmacology*
  • Lymphocytes, Tumor-Infiltrating / drug effects*
  • Lymphocytes, Tumor-Infiltrating / immunology
  • Lymphocytes, Tumor-Infiltrating / metabolism
  • Male
  • Middle Aged
  • Programmed Cell Death 1 Receptor / antagonists & inhibitors*
  • Programmed Cell Death 1 Receptor / metabolism
  • Signal Transduction
  • Tumor Escape / drug effects
  • Tumor Microenvironment

Substances

  • Antibodies, Monoclonal, Humanized
  • B7-H1 Antigen
  • CD274 protein, human
  • Cyclooxygenase 2 Inhibitors
  • Immune Checkpoint Inhibitors
  • PDCD1 protein, human
  • Programmed Cell Death 1 Receptor
  • pembrolizumab
  • Cyclooxygenase 2
  • PTGS2 protein, human