title: Helicobacter pylori environmental interactions: effect of acidic conditions on H. pylori-induced gastric mucosal interleukin-8 production.
abstract: To explore the interactions between the host, environment and bacterium responsible for the different manifestations of Helicobacter pylori infection, we examined the effect of acidic conditions on H. pylori-induced interleukin (IL)-8 expression. AGS gastric epithelial cells were exposed to acidic pH and infected with H. pylori[wild-type strain, its isogenic cag pathogenicity island (PAI) mutant or its oipA mutant]. Exposure of AGS cells to acidic pH alone did not enhance IL-8 production. However, following exposure to acidic conditions, H. pylori infection resulted in marked enhancement of IL-8 production which was independent of the presence of the cag PAI and OipA, indicating that H. pylori and acidic conditions act synergistically to induce gastric mucosal IL-8 production. In neutral pH environments H. pylori-induced IL-8 induction involved the NF-kappaB pathways, the extracellular signal-regulated kinase (ERK)-->c-Fos/c-Jun-->activating protein (AP-1) pathways, JNK-->c-Jun-->AP-1 pathways and the p38 pathways. At acidic pH H. pylori-induced augmentation of IL-8 production involved markedly upregulated the NF-kappaB pathways and the ERK-->c-Fos-->AP-1 pathways. In contrast, activation of the JNK-->c-Jun-->AP-1 pathways and p38 pathways were pH independent. These results might explain the clinical studies in which patients with duodenal ulcers had higher levels of IL-8 in the antral gastric mucosa than patients with simple H. pylori gastritis.
authors.affiliation: Department of Medicine-Gastroenterology, Michael E. DeBakey Veterans Affairs Medical Center and Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Il Ju
authors.initials: IJ
authors.lastname: Choi
authors.forename: Saori
authors.initials: S
authors.lastname: Fujimoto
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Yamauchi
authors.forename: David Y
authors.initials: DY
authors.lastname: Graham
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamaoka
mesh_terms: D002460:Cell Line; D004381:Duodenal Ulcer / Q000378:metabolism / Q000382:microbiology; D004847:Epithelial Cells / Q000378:metabolism / Q000382:microbiology; D005753:Gastric Mucosa / Q000378:metabolism / Q000382:microbiology*; D005756:Gastritis / Q000378:metabolism / Q000382:microbiology; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000502:physiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016209:Interleukin-8 / Q000096:biosynthesis*; D015398:Signal Transduction
chemical_list: D016209:Interleukin-8