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Analysis of the relationship between invasive capability of Helicobacter pylori and gastroduodenal diseases
Xiaoyan Zhang1, Jie Zhang1, Yunbin Lin1
1Key Laboratory of Ministry of Education for Gastrointestinal Cancer, School of Basic Medical Sciences, Fujian Medical University, Fuzhou 350108, PR China.
Abstract:
Helicobacter pylori (H. pylori) may enter into host cells, maybe as a facultative intracellular pathogen. This study aims to reveal the roles of internalized H. pylori in the bacterial pathopoiesis. Transmission electron microscopy was used to observe the invasion of H. pylori. Invasion rates of H. pylori (two standard strains and 43 clinical strains) were examined by gentamicin invasion assay. The cagA, cagE and vacA genes of H. pylori were detected by PCR. The cagA 3'region (cagA-EPIYA) of each strain was sequenced. The secretion of IL-8 from AGS cells and activity of NF-κB induced by intracellular H. pylori were tested by ELISA and the dual-luciferase reporter assay system, respectively. It was found that H. pylori could adhere to and invade AGS cells, then continue to survive and multiply in the cytoplasm. The average invasion rate of H. pylori gastric cancer plants and that of ulcer plants were both higher than that of gastritis plants (P ≈ 0.0001). In the clinical strains, cagA, vacA and cagE were all positive; cagA-EPIYA genotypes included ABD 90.7% (39/43) and ABBD 9.3% (4/43), all without comparability. Notably, the average invasion rate of H. pylori vacA s1c-i1-m1b plants was higher than that of vacA s1c-i1-m2 plants (P=0.0445). In addition, the intracellular H. pylori all could induce IL-8 secretion, which was decreased after cells were pretreated with anti-β1-integrin antibody or SN-50 (an NF-κB inhibitor). The intracellular H. pylori all activated NF-κB, which would be inhibited after cells were pretreated with anti-β1-integrin antibody. These results demonstrate that H. pylori invasive ability and disease severity have a positive correlation, and this intension of invasive ability is associated with the vacA mid-region, not with cagA, cagA-EPIYA or cagE. It is possible that cagA and cagE are essential for the bacterial invasion. Internalized H. pylori can activate NF-κB signal pathway and induce IL-8 secretion, which suggests that H. pylori invasion may be an important strategy to play a role in the development of H. pylori associated diseases.
Insights
Helicobacter pylori can invade host cells, correlating with disease severity. This invasion activates the NF-κB pathway and induces IL-8 secretion, suggesting a key role in H. pylori-associated diseases.
Area of Science:
- Microbiology
- Cell Biology
- Pathogenesis
Background:
- Helicobacter pylori (H. pylori) is a pathogen implicated in various gastrointestinal diseases.
- The intracellular behavior of H. pylori and its role in disease development are not fully understood.
Purpose of the Study:
- To investigate the intracellular roles of H. pylori in bacterial pathogenesis.
- To determine the correlation between H. pylori invasion ability and disease severity.
- To elucidate the signaling pathways activated by intracellular H. pylori.
Main Methods:
- Transmission electron microscopy to visualize bacterial invasion.
- Gentamicin invasion assay to quantify invasion rates.
- Polymerase chain reaction (PCR) to detect virulence genes (cagA, cagE, vacA).
- DNA sequencing of the cagA 3' region (cagA-EPIYA).
- ELISA for IL-8 secretion and dual-luciferase reporter assay for NF-κB activity.
Main Results:
- H. pylori successfully invaded, survived, and multiplied within AGS cells.
- Higher invasion rates were observed in strains from gastric cancer and ulcer patients compared to gastritis patients (P ≈ 0.0001).
- Invasion ability correlated positively with H. pylori vacA mid-region genotype (s1c-i1-m1b vs. s1c-i1-m2; P=0.0445).
- Intracellular H. pylori induced IL-8 secretion and activated the NF-κB pathway, which was inhibited by anti-β1-integrin antibody or an NF-κB inhibitor (SN-50).
Conclusions:
- H. pylori invasive ability is positively correlated with disease severity and associated with the vacA mid-region.
- Internalized H. pylori activates the NF-κB signaling pathway, leading to IL-8 secretion.
- Bacterial invasion represents a significant strategy in the pathogenesis of H. pylori-associated diseases.
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