Increased programmed death-ligand-1 expression in human gastric epithelial cells in Helicobacter pylori infection

B7‐H1 [programmed death‐ligand‐1 (PD‐L1)] is a B7‐family member that binds to programmed death‐1 (PD‐1). Recently, deficiency of PD‐L1 has been demonstrated to result in accelerated gastric epithelial cell damage in gastritis, and PD‐L1 is suggested to play a critical role in regulating T cell homeostasis. Here, we aimed to gain more insight into gastric PD‐L1 expression, regulation and function during Helicobacter pylori infection. PD‐L1 expression in human gastric epithelial cells was analysed using Western blotting, quantitative polymerase chain reaction and fluorescence activated cell sorter analysis. Furthermore, co‐culture experiments of human gastric epithelial cells with primary human T cells or Jurkat T cells were conducted. PD‐L1 expression in primary human gastric epithelial cells was strongly enhanced by H. pylori infection and activated T cells, and augmented markedly by further stimulation with interferon‐γ or tumour necrosis factor‐α. Moreover, PD‐L1 expression in gastric epithelial cells significantly induced apoptosis of T cells. Our results indicate that a novel bidirectional interaction between human gastric epithelial cells and lymphocytes modulates PD‐L1 expression in human gastric epithelial cells, contributing to the unique immunological properties of the stomach.