Helicobacter pylori water soluble surface proteins prime human neutrophils for enhanced production of reactive oxygen species and stimulate chemokine production

Abstract

Backgrounds/aims: Chronic gastritis induced by Helicobacter pylori is characterised by considerable neutrophil infiltration into the gastric mucosa without mucosal invasion of bacteria. Bacteria have different characteristics with respect to their ability to stimulate human neutrophils to produce reactive oxygen species and chemokines. The aim of this study was to examine the effects of H pylori water extracts on the oxidative burst and chemokine production of human neutrophils.

Methods: Helicobacter pylori cells were extracted by harvesting into distilled water and centrifugation. Neutrophils were incubated with H pylori water extracts and the production of reactive oxygen species was measured using luminol dependent chemiluminescence (LmCL). In addition, the concentrations of chemokines (interleukin 8 (IL-8), macrophage inflammatory protein 1-alpha (MIP1-alpha), and MIP1-beta) were measured by enzyme linked immunosorbent assay. Neutrophils were also stimulated by opsonised zymosan (OZ) after preincubation with H pylori water extracts.

Results: Helicobacter pylori water extracts alone induced only a weak oxidative burst but preincubation of neutrophils with water extracts dose dependently enhanced the LmCL response stimulated by OZ. Helicobacter pylori water extracts also stimulated neutrophil IL-8 production, although MIP-1beta production was only stimulated weakly, and MIP-1alpha was not stimulated at all.

Conclusions: Helicobacter pylori products in water extracts may have a role in the activation and migration of neutrophils, which results in enhanced oxidative damage to gastric mucosa. These findings may explain the pathology of H pylori induced gastritis, in which there is little invasion of bacteria into the gastric mucosa.

Figure 1

Luminol dependent chemiluminescence (LmCL) response pattern stimulated by Helicobacter pylori water extracts and H pylori cells. Stimulation of the production of neutrophil reactive oxygen species by H pylori cells depended on the concentration of the preincubation H pylori water extracts.

Figure 2

The peak value of the luminol dependent chemiluminescence (LmCL) response of neutrophils stimulated by Helicobacter pylori after 30 minutes of preincubation with H pylori water extracts. The highest LmCL response significantly correlated with the concentration of the water extracts (r = 0.770; p < 0.001). Data are the average of the results of two different experiments run in at least duplicate, and the bars represent SD.

Figure 3

Interleukin 8 (IL-8) production by neutrophils stimulated with Helicobacter pylori or zymosan. Data are presented as mean (SE). *The IL-8 concentration is significantly higher compared with neutrophils not stimulated by H pylori water extracts (p < 0.01). Data are the average of the results of two different experiments run in at least duplicate, and the bars represent SD.