Helicobacter pylori vacuolating cytotoxin inhibits T lymphocyte activation

摘要

Helicobacter pylori (Hp) vacuolating cytotoxin VacA induces cellular vacuolation in epithelial cells. We found that VacA could efficiently block proliferation of T cells by inducing a G(1)/S cell cycle arrest. It interfered with the T cell receptor/interleukin-2 (IL-2) signaling pathway at the level of the Ca2+-calmodulin-dependent phosphatase calcineurin. Nuclear translocation of nuclear factor of activated T cells (NFAT), a transcription factor acting as a global regulator of immune response genes, was abrogated, resulting in downregulation of IL-2 transcription. VacA partially mimicked the activity of the immunosuppressive drug FK506 by possibly inducing a local immune suppression, explaining the extraordinary chronicity of Hp infections. [References: 25]