Helicobacter pylori VacA Induces Programmed Necrosis in Gastric Epithelial Cells

• Published in: Infection and Immunity Vol. 79; no. 7; pp. 2535 - 2543
• Main Authors: Radin, Jana N, González-Rivera, Christian, Ivie, Susan E, McClain, Mark S, Cover, Timothy L
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.07.2011
• Subjects: adenosine triphosphate; Adenosine Triphosphate - metabolism; Bacterial Proteins - genetics; Bacterial Proteins - physiology; Bacterial Toxins - metabolism; Bacteriology; Biological and medical sciences; Blotting, Western; Caspases - metabolism; Cell Death; Cell Line; Cell Line, Tumor; death; epithelial cells; Epithelial Cells - microbiology; Epithelial Cells - pathology; Fundamental and applied biological sciences. Psychology; Gastric Mucosa - microbiology; Gastric Mucosa - pathology; Gastritis - microbiology; Gram-negative bacteria; Helicobacter pylori; Helicobacter pylori - metabolism; Helicobacter pylori - pathogenicity; HMGB1 Protein - metabolism; Humans; inflammation; Ion Channels; L-Lactate Dehydrogenase - metabolism; lactate dehydrogenase; Microbiology; Miscellaneous; Molecular Pathogenesis; mutants; Necrosis; pathogenesis; Peptic Ulcer - microbiology; peptic ulcers; Poly(ADP-ribose) Polymerases - metabolism; proteins; stomach; stomach neoplasms; Stomach Neoplasms - microbiology; toxins; virulence; Virulence Factors - physiology; Spirillaceae; Bacteria; Epithelial cell; Spirillales; Helicobacter pylori; Immunity
• ISSN: 0019-9567; 1098-5522
• DOI: 10.1128/iai.01370-10

Helicobacter pylori is a Gram-negative bacterium that colonizes the human stomach and contributes to the development of peptic ulcer disease and gastric cancer. The secreted pore-forming toxin VacA is one of the major virulence factors of H. pylori. In the current study, we show that AZ-521 human gastric epithelial cells are highly susceptible to VacA-induced cell death. Wild-type VacA causes death of these cells, whereas mutant VacA proteins defective in membrane channel formation do not. Incubation of AZ-521 cells with wild-type VacA results in cell swelling, poly(ADP-ribose) polymerase (PARP) activation, decreased intracellular ATP concentration, and lactate dehydrogenase (LDH) release. VacA-induced death of these cells is a caspase-independent process that results in cellular release of histone-binding protein high mobility group box 1 (HMGB1), a proinflammatory protein. These features are consistent with the occurrence of cell death through a programmed necrosis pathway and suggest that VacA can be included among the growing number of bacterial pore-forming toxins that induce cell death through programmed necrosis. We propose that VacA augments H. pylori-induced mucosal inflammation in the human stomach by causing programmed necrosis of gastric epithelial cells and subsequent release of proinflammatory proteins and may thereby contribute to the pathogenesis of gastric cancer and peptic ulceration.