Rapid interaction of Helicobacter pylori with microvilli of the polar human gastric epithelial cell line NCI-N87

HopQ impacts the integrin α5β1-independent NF-κB activation by Helicobacter pylori in CEACAM expressing cells

Helicobacter pylori infection persists in more than half of the world's population and represents a risk factor for peptic ulcer disease and gastric cancer. Virulent strains of H. pylori carry a cag pathogenicity island (cagPAI), which encodes a type IV secretion system (T4SS) with the capability to inject the effector protein cytotoxin-associated gene A (CagA) into eukaryotic cells. Colonisation of the gastric epithelium by H. pylori provokes direct activation of the proinflammatory and survival factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). We investigated the impact of host cell receptor integrin α5β1 and the bacterial adhesin HopQ on the NF-κB activation. We found that H. pylori induced early T4SS-dependent, but CagA-independent canonical NF-κB signalling in polarized, apical infected NCI-N87 cells. Integrin-dependent CagA translocation was hardly detectable, as integrin β1 was sparsely located at the apical surface of polarized NCI-N87 cells. Knockdown experiments indicated that integrin α5β1 and integrin linked kinase (ILK) were dispensable for NF-κB activation in H. pylori infection. Thus, there exists no common mechanism, which mediates integrin α5β1-dependent H. pylori-triggered CagA translocation and the activation of NF-κB. Further, we report that H. pylori adhesin HopQ, which binds to a specific subset of carcinoembryonic antigen-related cell adhesion molecules (CEACAMs), promotes canonical NF-κB activation in AGS and NCI-N87 cells, but not in HeLa cells, which are devoid of these CEACAMs. Noteworthy, these effects were not mediated by reduced adhesion, indicating additional functions of HopQ.

Anti-Helicobacter pylori Properties of the Ant-Venom Peptide Bicarinalin

The venom peptide bicarinalin, previously isolated from the ant Tetramorium bicarinatum, is an antimicrobial agent with a broad spectrum of activity. In this study, we investigate the potential of bicarinalin as a novel agent against Helicobacter pylori, which causes several gastric diseases. First, the effects of synthetic bicarinalin have been tested against Helicobacter pylori: one ATCC strain, and forty-four isolated from stomach ulcer biopsies of Peruvian patients. Then the cytoxicity of bicarinalin on human gastric cells and murine peritoneal macrophages was measured using XTT and MTT assays, respectively. Finally, the preventive effect of bicarinalin was evaluated by scanning electron microscopy using an adherence assay of H. pylori on human gastric cells treated with bicarinalin. This peptide has a potent antibacterial activity at the same magnitude as four antibiotics currently used in therapies against H. pylori. Bicarinalin also inhibited adherence of H. pylori to gastric cells with an IC50 of 0.12 μg·mL-1 and had low toxicity for human cells. Scanning electron microscopy confirmed that bicarinalin can significantly decrease the density of H. pylori on gastric cells. We conclude that Bicarinalin is a promising compound for the development of a novel and effective anti-H. pylori agent for both curative and preventive use.

Effect of Mieyou decoction on TLRs/NF-κB65 signal pathway in mice with Helicobacter pylori associated gastritis with splenogastric hygropyrexia syndrome

AIM: To detect the gastric expression of Toll-like receptor 2 (TLR2), TLR4, nuclear factor-kappa B 65 (NF-κB65), and serum levels of interleukin-6 (IL-6) and IL-8 in mice with Helicobacter pylori (H. pylori) associated gastritis with splenogastric hygropyrexia syndrome (SGHS), and to investigate the mechanism underlying the therapeutic effect of Mieyou decoction in the treatment of chronic gastritis.

METHODS: BALB/c mouse were randomly divided into five groups: a control group, a model group, a high-concentration Mieyou decoction group, a low-concentrations Mieyou decoction group, and a triple therapy group (tinidazole, clarithromycin and bismuth potassium citrate granules), with 14 rats in each group. The BALB/c model of H. pylori-associated gastritis with SGHS using a composite method (fatness food + hygropyrexia environment + H. pylori). After the success of modeling, continuous administration 14 d. Immunohistochemistry was used to detect the expression TLR2, TLR4 and NF-κB65 proteins in gastric tissue; qPCR was used to detect the expression of TLR2, TLR4 and NF-κB65 mRNAs; ELISA was used to detect the levels of IL-6 and IL-8 in serum.

RESULTS: Compared with the control group, the expression of TLR2, TLR4, NF-κB65 proteins and mRNAs, and serum levels of IL-6 and IL-8 in the model group were significantly increased. After therapy, the expression of TLR2, TLR4, NF-κB65 proteins and mRNAs, and serum levels of IL-6 and IL-8 in the high-concentration Mieyou decoction group, low-concentration Mieyou decoction group, and triple therapy group were significantly decreased compared with the model group. The expression of TLR2, TLR4, NF-κB65 proteins and mRNAs, and serum levels of IL-6 and IL-8 in the high-concentration Mieyou decoction group were higher than those in the triple therapy group, but the differences were not statistically significant.

CONCLUSION: Mieyou decoction has a role in the treatment of H. pylori-associated gastritis with SGHS possibly by intervening the TLRs/NF-κB65 signal pathway.