Mechanisms involved in Helicobacter pylori-induced interleukin-8 production by a gastric cancer cell line, MKN45

Abstract

Accumulating evidence suggests an important role of interleukin-8 (IL-8) in Helicobacter pylori infectionassociated chronic atrophic gastritis and peptic ulcer. We observed in this study that a gastric cancer-derived cell line, MKN45, produced a massive amount of IL-8 upon coculture with live H. pylori but not with killed H. pylori, H. pylori culture supernatants, or live H. pylori separated by a permeable membrane, indicating that IL-8 production requires a direct contact between the cells and live bacteria. Moreover, the tyrosine kinase inhibitor herbimycin but neither a protein kinase C inhibitor (staurosporine) nor a protein kinase A inhibitor (H89) inhibited IL-8 production by MKN45 cells cocultured with live bacteria, suggesting the involvement of a tyrosine kinase(s) in H. pylori-induced IL-8 production. In addition, coculture of H. pylori induced IL-8 mRNA expression in MKN45 cells and an increase in luciferase activity in cells which were transfected with a luciferase expression vector linked with a 5-flanking region of the IL-8 gene (bp ؊133 to ؉44), indicating that the induction of IL-8 production occurred at the transcriptional level. This region contain three cis elements important for induction of IL-8 gene expression: AP-1 (؊126 to ؊120 bp), NF-IL6 (؊94 to ؊81 bp), and NF-B (؊80 to ؊70 bp) binding sites. Mutation of the NF-B binding site abrogated completely the induction of luciferase activity, whereas that of the AP-1 site partially reduced the induction. However, mutation of the NF-IL6 binding site resulted in no decrease in the induction of luciferase activity. Moreover, specific NF-B complexes were detected in the nuclear proteins extracted from MKN45 cells which were infected with H. pylori. Collectively, these results suggest that H. pylori induced the activation of NF-B as well as AP-1, leading to IL-8 gene transcription.

Differential modulation of Helicobacter pylori lipopolysaccharide‐mediated TLR2 signaling by individual Pellino proteins

“…[58][59][60] Moreover, it has been shown that activation of both AP-1 and NF-ĸB is involved in the regulation of Il8 gene expression in MKN45 cells in response to H. pylori infection. 61 Additionally, overexpression of Pellino2 has been demonstrated to activate the ERK and JNK MAPK pathways, 44 and inhibition of Pellino2 expression attenuates TLR4-mediated activation of these kinases and the induction of proinflammatory cytokine genes. 62 As such, it is possible that Pellino2 regulates chemokine expression through pathways involving the MAPK axis of the TLR2-mediated response.…”

Helicobacter pyloriouter membrane protein HopQ identified as a novel T4SS-associated virulence factor

“…Both MAPK and NF-κB pathways culminate in the activation of several pro-inflammatory target genes, including the IL-8 gene (Aihara et al, 1997). Hence, we determined the potential of P12ΔhopQ to stimulate IL-8 secretion in AGS cells compared with P12 wild type and P12ΔcagPAI.…”

“…Also the T4SS itself induces host cell responses in gastric epithelial cells such as the activation of the transcription factor NF-κB (Glocker et al, 1998). Together with the transcription factor AP-1 (activator protein 1), NF-κB regulates the expression of interleukin 8 (IL-8) (Aihara et al, 1997;Sharma et al, 1998) and is involved in cellular apoptotic, proliferative and immune responses (Hoffmann and Baltimore, 2006).…”

H. pylori and cagA: Relationships with Gastric Cancer, Duodenal Ulcer, and Reflux Esophagitis and Its Complications

“…The mechanism by which the CPI enhances IL-8 secretion is unknown, but attachment to the mucosa appears critical [39,40]. For example, when a membrane is placed between H. pylori and the target cells, the pro-inflammatory activity was [40]. Whether internalization is also critical has not been addressed [40,41].…”

“…For example, when a membrane is placed between H. pylori and the target cells, the pro-inflammatory activity was [40]. Whether internalization is also critical has not been addressed [40,41].…”