Helicobacter pylori enhances tumor necrosis factor-related apoptosis-inducing ligand-mediated apoptosis in human gastric epithelial cells.
OBJECTIVE
To investigate the relations between tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and Helicobacter pylori (H pylori) infection in apoptosis of gastric epithelial cells and to assess the expression of TRAIL on the surface of infiltrating T-cells in H pylori-infected gastric mucosa.


METHODS
Human gastric epithelial cell lines and primary gastric epithelial cells were co-cultured with H pylori in vitro, then recombinant TRAIL proteins were added to the culture. Apoptosis of gastric epithelial cells was determined by a specific ELISA for cell death. Infiltrating lymphocytes were isolated from H pylori-infected gastric mucosa, and expression of TRAIL in T cells was analyzed by flow cytometry.


RESULTS
The apoptosis of gastric epithelial cell lines and primary human gastric epithelial cells was mildly increased by interaction with either TRAIL or H pylori alone. Interestingly, the apoptotic indices were markedly elevated when gastric epithelial cells were incubated with both TRAIL and H pylori (Control vs TRAIL and H pylori: 0.51+/-0.06 vs 2.29+/-0.27, P = 0.018). A soluble TRAIL receptor (DR4-Fc) could specifically block the TRAIL-mediated apoptosis. Further studies demonstrated that infiltrating T-cells in gastric mucosa expressed TRAIL on their surfaces, and the induction of TRAIL sensitivity by H pylori was dependent upon direct cell contact of viable bacteria, but not CagA and VacA of H pylori.


CONCLUSIONS
H pylori can sensitize human gastric epithelial cells and enhance susceptibility to TRAIL-mediated apoptosis. Modulation of host cell sensitivity to apoptosis by bacterial interaction adds a new dimension to the immunopathogenesis of H pylori infection.
Graduate Institute of Immunology, College of Medicine, National Taiwan University, No. 1, Sec. 1, Jen-Ai Road, Taipei, Taiwan, China.
Yi-Ying
YY
Wu
Hwei-Fang
HF
Tsai
We-Cheng
WC
Lin
Ai-Hsiang
AH
Chou
Hui-Ting
HT
Chen
Jyh-Chin
JC
Yang
Ping-I
PI
Hsu
Ping-Ning
PN
Hsu
D000942:Antigens, Bacterial / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D001426:Bacterial Proteins / Q000494:pharmacology; D002460:Cell Line; D002478:Cells, Cultured; D018920:Coculture Techniques; D017931:DNA Primers; D005753:Gastric Mucosa / Q000166:cytology / Q000382:microbiology / Q000473:pathology*; D016481:Helicobacter Infections / Q000473:pathology*; D016480:Helicobacter pylori; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000502:physiology; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000378:metabolism; D013601:T-Lymphocytes / Q000382:microbiology / Q000473:pathology; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000502:physiology
D000942:Antigens, Bacterial; D051017:Apoptosis Regulatory Proteins; D001426:Bacterial Proteins; D017931:DNA Primers; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori