Helicobacter pylori induction of eosinophil migration is mediated by the cag pathogenicity island via microbial-epithelial interactions

Abstract

The host immune response directed against Helicobacter pylori is ineffective in eliminating the organism and strains harboring the cag pathogenicity island augment disease risk. Because eosinophils are a prominent component of H. pylori-induced gastritis, we investigated microbial and host mechanisms through which H. pylori regulates eosinophil migration. Our results indicate that H. pylori increases production of the chemokines CCL2, CCL5, and granulocyte-macrophage colony-stimulating factor by gastric epithelial cells and that these molecules induce eosinophil migration. These events are mediated by the cag pathogenicity island and by mitogen-activated protein kinases, suggesting that eosinophil migration orchestrated by H. pylori is regulated by a virulence-related locus.

Figure 1

Co-culture of H. pylori with gastric epithelial cells induces eosinophil migration and chemokine production. A: Eosinophil migration toward supernatants harvested from MKN28 cells cultured alone or in the presence of wild-type H. pylori strain 60190. Bars represent the mean ± SEM of 7 experiments. *P < 0.003 vs control. B: Eosinophil migration toward supernatants harvested from MKN28 cells cultured alone (control) or in the presence of wild-type H. pylori strain 60190, isogenic cagA⁻, cagL⁻, slt⁻, or vacA⁻ mutants, or heat-killed H. pylori. Bars represent the mean ± SEM of 5 experiments. *P < 0.05 versus 60190.

Figure 2

Chemokines induced by H. pylori infection of gastric epithelial cells mediate eosinophil migration. A: Chemokine concentrations in the supernatants of MKN28 cells cultured alone or in the presence of H. pylori strain 60190. Bars represent the mean ± SEM of 5 experiments. *P = 0.013, 0.047, 0.0002, and 0.021 for CCL2, CCL3, CCL5, and GM-CSF, respectively, versus uninfected controls. B: Chemokine concentrations in the supernatants of MKN28 cells cultured alone or in the presence of H. pylori wild-type strain 60190 or isogenic cagA⁻, cagL⁻, slt⁻, or vacA⁻ mutants. Bars represent the mean ± SEM of 5 experiments. *P < 0.05 vs CCL2 control. **P < 0.05 vs CCL5 control. ***P < 0.05 vs GM-CSF control. C: Eosinophil migration toward media alone or increasing concentrations of the chemokines CCL11 (positive control), GM-CSF, CCL5, CCL2, or CCL3.

Figure 3

Effect of MAPK inhibition on H. pylori–induced eosinophil migration and gastric epithelial cell chemokine expression. A: Eosinophil migration toward supernatants harvested from MKN28 cells cultured alone or in the presence of wild-type H. pylori strain 60190 with or without SB203580 (p38i), PD98059 (ERKi), or JNK inhibitor II (JNKi). Bars represent the mean ± SEM of 5 experiments. *P < 0.05 versus 60190 in the presence of vehicle (dimethyl sulfoxide) alone. B: Chemokine expression in cell lysates harvested from MKN28 cells cultured alone or in the presence of H. pylori strain 60190 with or without SB203580 (p38i) and PD98059 (ERKi) as assessed by real-time RT-PCR. Bars represent the mean ± SEM of 5 experiments. *P = 0.0109 versus 60190 in the presence of vehicle (dimethyl sulfoxide) alone.