Immune Evasion

Helicobacter pylori, which infects roughly half of the world population, can cause chronic and persistent infections of the stomach that can eventually lead to chronic gastritis, gastric and duodenal ulceration, and even malignancies. Gebert et al. now show how H. pylori can suppress the activation and proliferation of T lymphocytes. Vacuolating cytotoxin (VacA) is secreted by the bacteria and targets the T cell receptor signaling pathway. VacA interferes with the Ca2+-dependent phosphatase calcineurin, which blocks nuclear translocation of the transcription factor NFAT. NFAT coordinates the expression of genes involved in inducing inflammation and controlling an efficient immune response. This strategy of immune suppression in the virulence of H. pylori could have implications for other chronically persisting bacterial pathogens as well. B. Gebert, W. Fischer, E. Weiss, R. Hoffmann, R. Haas, Helicobacter pylori vacuolating cytotoxin inhibits T lymphocyte activation, Science 301, 1099-1102 (2003). [Abstract] [Full Text]