title: Helicobacter pylori VacA activates NF-kappaB in T cells via the classical but not alternative pathway.
abstract: BACKGROUND
  Helicobacter pylori secretes vacuolating cytotoxin (VacA) that damages the gastric epithelium by erosion and loosening of tight junctions. VacA has also immunosuppressive effects, inhibiting interleukin (IL)-2 secretion by interference with the T cell receptor/IL-2 signaling pathway. This study investigated the effect of VacA on gene expression of T cells.
  
  
  METHODS
  Gene expression profile of a T cell line, Jurkat, was analyzed by the cDNA microarray technique after VacA challenge. The expression of specific mRNAs was assessed by reverse transcription-polymerase chain reaction. Interleukin (IL)-8 concentrations in culture supernatants and cell surface expression of CD69 were measured by enzyme-linked immunosorbent assay and flow cytometry, respectively. We evaluated nuclear factor-kappaB (NF-kappaB) activation in Jurkat cells challenged with VacA by luciferase assay, electrophoretic mobility shift assay, and Western blot analysis.
  
  
  RESULTS
  VacA produced two or greater fold up-regulation of expression of 60 genes. Most of these genes were associated with signal transduction, regulation of gene expression, apoptosis, and inflammation. Up-regulation of four genes (IL8, IL2RA, ICAM1, and CD69) was confirmed. The supernatants of cells incubated with VacA showed significantly higher secretion levels of IL-8 than those incubated without VacA. VacA also induced the cell surface expression of CD69. Since microarray analysis indicated NF-kappaB was involved in the transcriptional activation of the above genes, we examined NF-kappaB signaling pathway. VacA activated NF-kappaB via classical but not alternative pathway.
  
  
  CONCLUSIONS
  VacA has two paradoxical effects on T cells, immunosuppression, and proinflammatory effects. The latter is mediated by NF-kappaB activation.
authors.affiliation: Division of Molecular Virology and Oncology, Graduate School of Medicine, University of the Ryukyus, Nishihara, Okinawa, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Takeshima
authors.forename: Koh
authors.initials: K
authors.lastname: Tomimori
authors.forename: Reika
authors.initials: R
authors.lastname: Takamatsu
authors.forename: Chie
authors.initials: C
authors.lastname: Ishikawa
authors.forename: Fukunori
authors.initials: F
authors.lastname: Kinjo
authors.forename: Toshiya
authors.initials: T
authors.lastname: Hirayama
authors.forename: Jiro
authors.initials: J
authors.lastname: Fujita
authors.forename: Naoki
authors.initials: N
authors.lastname: Mori
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology*; D002460:Cell Line; D020869:Gene Expression Profiling; D016481:Helicobacter Infections / Q000235:genetics* / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D016480:Helicobacter pylori / Q000235:genetics / Q000276:immunology*; D006801:Humans; D016328:NF-kappa B / Q000235:genetics* / Q000276:immunology; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D016328:NF-kappa B; C074689:VacA protein, Helicobacter pylori