Interleukin-8 response of gastric epithelial cell lines to Helicobacter pylori stimulation in vitro

Abstract

Gastric infection with Helicobacter pylori activates a mucosal inflammatory response by mononuclear cells and neutrophils that includes expression of cytokines interleukin-1␤ (IL-1␤), IL-6, tumor necrosis factor alpha, and IL-8. In this study, we analyzed the IL-8 response of human gastric cancer cell lines (Kato III, AGS, and MKN28) to H. pylori infection in vitro. IL-8 mRNA expression was detected by reverse transcription-PCR amplification of RNA extracted from epithelial cells after incubation with different H. pylori wild-type and mutant strains, and IL-8 secretion was measured by an enzyme-linked immunosorbent assay. Exposure to viable H. pylori induced IL-8 mRNA and protein synthesis in all three gastric cell lines but not in nongastric epithelial cell lines. Heat-killed H. pylori and a crude cytotoxin preparation did not induce significant IL-8 secretion. IL-8 mRNA peaked between 2 and 4 h postinfection, and IL-8 protein production was maximal 24 h postinfection. Exposure of gastric carcinoma cells to other gastrointestinal bacteria, such as Pseudomonas aeruginosa, Campylobacter jejuni, and Escherichia coli, but not Campylobacter fetus, induced IL-8 synthesis. Wild-type strains that expressed the vacuolating cytotoxin (Tox ؉) and a cytotoxin-associated gene (cagA) product (CagA ؉) induced significantly more IL-8 than did CagA ؊ Tox ؊ strains. However, there was no decrease in IL-8 induction by isogenic mutants of CagA ؊ , Tox ؊ , or Cag ؊ Tox ؊ strains or by a mutant lacking the urease subunits. These results indicate that exposure to H. pylori and other gram-negative organisms that do not colonize the gastric mucosa induces IL-8 production by gastric carcinoma cells in vitro. Although the CagA ؉ Tox ؉ phenotype of H. pylori is associated with enhanced IL-8 production by gastric cell lines, other bacterial constituents are clearly essential.

Reduced activation of inflammatory responses in host cells by mouse-adapted Helicobacter pylori isolates

“…Although these findings might seem contradictory, it is known that multiple transcription factors synergistically activate the transcription of genes encoding pro-inflammatory cytokines, such as IL-8, depending upon the cell type (Matsusaka et al, 1993;Mastronarde et al, 1996). In the AGS cell line used here, H. pylori-induced production of IL-8 was shown to be regulated by NF-kB, as well as by two other transcription factors, activator protein 1 (AP-1) and nuclear factor-IL-6 (NF-IL-6) (Sharma et al, 1995;Naumann et al, 1999). Also, the ability of H. pylori strains to mediate DNA binding of NF-kB and AP-1 in AGS cells has been reported to be dependent upon the presence of a Cag PAI (Sharma et al, 1995;Naumann et al, 1999); in contrast, NF-IL-6 binding occurs independently of the Cag PAI phenotype of the strain (Sharma et al, 1995).…”

Circulating antibodies to the 60-kD heat shock protein (hsp) family in patients with Helicobacter pylori infection

“…CagA-positive strains have greater pathogenic potential than CagA-negative strains because of their ability to increase mucosal cytokine expression [21][22][23][24] and association with increased polymorphonuclear cell infiltration [9,25]. Both polymorph infiltration as well as VacA-mediated epithelial damage may contribute to enhanced epithelial permeability, whilst increased chemokine expression may lead to B lymphocyte activation and hence raised anti-hsp60 levels.…”

TheHelicobacter pyloriplasticity region locusjhp0947–jhp0949is associated with duodenal ulcer disease and interleukin-12 production in monocyte cells

“…The cytotoxin-associated gene (cag) pathogenicity island (PAI) was the first H. pylori factor for which a role in host cell cytokine production was demonstrated [7]. The cag PAI is present in 50-70% of H. pylori isolates from Western populations, and in 90% or more of the strains in Eastern populations [1].…”

“…The cag PAI is present in 50-70% of H. pylori isolates from Western populations, and in 90% or more of the strains in Eastern populations [1]. It plays an important role in the induction of IL-8 production in gastric epithelial cells [7]. Although IL-8 is an important factor of the innate host immune response during initial H. pylori colonization, it is not required for development of the pro-inflammatory T helper 1 (Th1) immune response.…”