Helicobacter pylori Vacuolating Toxin
Steven R. Blanke and Timothy L. Cover
from: Helicobacter pylori: Molecular Genetics and Cellular Biology (Edited by: Yoshio Yamaoka). Caister Academic Press, U.K. (2008)
Helicobacter pylori VacA is a protein toxin that is secreted into the extracellular space by a Type V autotransporter mechanism. Specific allelic variants of vacA exhibit different levels of toxin activity in vitro and are associated with different risks of gastroduodenal disease in H. pylori-infected humans. The structural features and the cell-modulating activities of VacA are distinct from those of any other known bacterial toxin. VacA can exert a wide array of effects on gastric epithelial cells, including alteration of endocytic compartments, alteration of mitochondrial membrane permeability, and activation of signal transduction pathways. Moreover, VacA inhibits activation and proliferation of T cells and can have effects on several other types of immune cells. VacA contributes to the ability of H. pylori to colonize the stomach and also contributes to the pathogenesis of H. pylori-associated peptic ulcer disease and gastric cancer. VacA displays both immunosuppressive as well as pro-inflammatory activities in vitro, underscoring the potentially complex role of this toxin in vivo read more ...