Helicobacter pylori infection upregulates endothelial nitric oxide synthase expression and induces angiogenesis in gastric mucosa of dyspeptic patients

Helicobacter pylori infection induces abnormal expression of pro-angiogenic gene ANGPT2 and miR-203a in AGS gastric cell line

Helicobacter pylori colonizes the stomach and induces an inflammatory response that can develop into gastric pathologies including cancer. The infection can alter the gastric vasculature by the deregulation of angiogenic factors and microRNAs. In this study, we investigate the expression level of pro-angiogenic genes (ANGPT2, ANGPT1, receptor TEK), and microRNAs (miR-135a, miR-200a, miR-203a) predicted to regulate those genes, using H. pylori co-cultures with gastric cancer cell lines. In vitro infections of different gastric cancer cell lines with H. pylori strains were performed, and the expression of ANGPT1, ANGPT2, and TEK genes, and miR-135a, miR-200a, and miR-203a, was quantified after 24 h of infection (h.p.i.). We performed a time course experiment of H. pylori 26695 infections in AGS cells at 6 different time points (3, 6, 12, 28, 24, and 36 h.p.i.). The angiogenic response induced by supernatants of non-infected and infected cells at 24 h.p.i. was evaluated in vivo, using the chicken chorioallantoic membrane (CAM) assay. In response to infection, ANGPT2 mRNA was upregulated at 24 h.p.i, and miR-203a was downregulated in AGS cells co-cultured with different H. pylori strains. The time course of H. pylori 26695 infection in AGS cells showed a gradual decrease of miR-203a expression concomitant with an increase of ANGPT2 mRNA and protein expression. Expression of ANGPT1 and TEK mRNA or protein could not be detected in any of the infected or non-infected cells. CAM assays showed that the supernatants of AGS-infected cells with 26695 strain induced a significantly higher angiogenic and inflammatory response. Our results suggest that H. pylori could contribute to the process of carcinogenesis by downregulating miR-203a, which further promotes angiogenesis in gastric mucosa by increasing ANGPT2 expression. Further investigation is needed to elucidate the underlying molecular mechanisms.

Helicobacter pylori infection induces gastric precancerous lesions and persistent expression of Angpt2, Vegf-A and Tnf-A in a mouse model

Introduction

Helicobacter pylori colonizes the gastric mucosa and induces chronic inflammation.

Methods

Using a mouse model of H. pylori-induced gastritis, we evaluated the mRNA and protein expression levels of proinflammatory and proangiogenic factors, as well as the histopathological changes in gastric mucosa in response to infection. Five- to six-week-old female C57BL/6N mice were challenged with H. pylori SS1 strain. Animals were euthanized after 5-, 10-, 20-, 30-, 40- and 50-weeks post infection. mRNA and protein expression of Angpt1, Angpt2, VegfA, Tnf-α, bacterial colonization, inflammatory response and gastric lesions were evaluated.

Results

A robust bacterial colonization was observed in 30 to 50 weeks-infected mice, which was accompanied by immune cell infiltration in the gastric mucosa. Compared to non-infected animals, H. pylori-colonized animals showed an upregulation in the expression of Tnf-A, Angpt2 and VegfA at the mRNA and protein levels. In contrast, Angpt1 mRNA and protein expression was downregulated in H. pylori-colonized mice.

Conclusion

Our data show that H. pylori infection induces the expression of Angpt2, Tnf-A and Vegf-A in murine gastric epithelium. This may contribute to the pathogenesis of H. pylori-associated gastritis, however the significance of this should be further addressed.

Helicobacter pylori Infection in Geriatric Patients: Current Situation and Treatment Regimens

Helicobacter pylori (H. pylori) has so far infected more than half the global population. It is the most important and controllable risk factor for gastric cancer. The elderly, who are at a higher incidence of the infection, are also commonly found to develop antibiotic resistance. The symptoms, diagnosis, clinical features (of gastric or extra-digestive diseases), and treatment of H. pylori infection in the elderly, are different from that in the non-elderly. Health conditions, including comorbidities and combined medication have limited the use of regular therapies in elderly patients. However, they can still benefit from eradication therapy, thus preventing gastric mucosal lesions and gastric cancer. In addition, new approaches, such as dual therapy and complementary therapy, have the potential to treat older patients with H. pylori infection.

Helicobacter pylori urease induces pro-inflammatory effects and differentiation of human endothelial cells: Cellular and molecular mechanism

BACKGROUND

Helicobacter pylori urease (HPU) is a key virulence factor that enables bacteria to colonize and survive in the stomach. We early demonstrated that HPU, independent of its catalytic activity, induced inflammatory and angiogenic responses in vivo and directly activated human neutrophils to produce reactive oxygen species (ROS). We have investigated the effects of HPU on endothelial cells, focusing on the signaling mechanism involved.

METHODS

Monolayers of human microvascular endothelial cells (HMEC-1) were stimulated with HPU (up to 10 nmol/L): Paracellular permeability was accessed through dextran-FITC passage. NO and ROS production was evaluated using intracellular probes. Proteins or mRNA expressions were detected by Western blotting and fluorescence microscopy or qPCR assays, respectively.

RESULTS

Treatment with HPU enhanced paracellular permeability of HMEC-1, preceded by VE-cadherin phosphorylation and its dissociation from cell-cell junctions. This caused profound alterations in actin cytoskeleton dynamics and focal adhesion kinase (FAK) phosphorylation. HPU triggered ROS and nitric oxide (NO) production by endothelial cells. Increased intracellular ROS resulted in nuclear factor kappa B (NF-κB) activation and upregulated expression of cyclooxygenase-2 (COX-2), hemeoxygenase-1 (HO-1), interleukin-1β (IL-1β), and intercellular adhesion molecule-1 (ICAM-1). Higher ICAM-1 and E-selectin expression was associated with increased neutrophil adhesion on HPU-stimulated HMEC monolayers. The effects of HPU on endothelial cells were dependent on ROS production and lipoxygenase pathway activation, being inhibited by esculetin. Additionally, HPU improved vascular endothelial growth factor receptor 2 (VEGFR-2) expression.

CONCLUSION

The data suggest that the pro-inflammatory properties of HPU drive endothelial cell to a ROS-dependent program of differentiation that contributes to the progression of H pylori infection.

Interaction of Helicobacter pylori infection and nonsteroidal anti-inflammatory drugs in gastric and duodenal ulcers

BACKGROUND

Gastric (GU) and duodenal ulcers (DU) are in most instances either induced by Helicobacter pylori infection or by nonsteroidal anti-inflammatory drugs (NSAIDs). Whether eradication of H. pylori is beneficial in NSAID users for preventing NSAID induced GU and DU has been the focus of different studies.

MATERIALS AND METHODS

Mechanisms shared by both H. pylori and NSAIDs for the induction of GU and DU were reviewed and randomized controlled trials on H. pylori eradication for prevention and healing of GU and DU in patients requiring NSAID therapy were identified by a PubMed search.

RESULTS

Key factors in the induction of GU and DU for both H. pylori and NSAIDs are a decrease in pH, imbalance between apoptosis and proliferation, reduction in mucosal blood flow, and recruitment of polymorphonucleates in distinct compartments. For primary ulcer prevention, H. pylori eradication before starting an NSAID therapy reduces the risk of NSAID induced GU and virtually abolishes the risk of DU. H. pylori eradication alone is not sufficient for secondary prevention of NSAID induced GU and DU. H. pylori infection appears to further increase the protective effects of proton-pump inhibitors (PPI) to reduce the risk of ulcer relapse. H. pylori eradication does not influence the healing of both GU and DU if NSAID intake is discontinued.

CONCLUSIONS

Duodenal ulcer is more closely related to H. pylori infection than GU in NSAID users. H. pylori eradication is recommended for primary prevention of GU and DU in patients requiring NSAID therapy. PPI therapy is mandatory for secondary prevention of gastroduodenal ulcers, and appears to further reduce the risk of ulcer relapse in the presence of H. pylori.

Endothelial nitric oxide synthase (eNOS) is not upregulated in gastric mucosa of Helicobacter pylori (H. pylori)-positive patients with type 2 diabetes mellitus

AIM

To evaluate the expression of eNOS and CD34 in gastric mucosa of Helicobacter pylori (H. pylori) positive diabetic patients, in correlation with glycaemic control and diabetic autonomic neuropathy (DAN).

METHODS

We prospectively studied 49 diabetic type 2 patients (29 women, mean age 65.32+/-8.56 years) and 30 control subjects (15 women, mean age 58.47+/-12.40) that underwent endoscopy. Biopsies from the body and antrum were evaluated for H. pylori-gastritis, eNOS and angiogenic marker CD34 expression. Statistical analysis in correlation with mean glycosylated haemoglobin (HbA1c) of the last 3 years, and DAN was performed.

RESULTS

The two groups were matched for age (p=0.144), sex (p=0.335), H. pylori-infection (p=0.617) and degree of gastritis (p=0.78). eNOS and CD34 attenuated expression correlated with diabetes mellitus (DM) in the corpus (p=0.009 and 0.02, respectively). eNOS and CD34 expression was upregulated in H. pylori-positive controls but not in H. pylori-positive diabetic patients (p=0.010 and 0.007 for the corpus and p=0.036 and 0.047 for the antrum, respectively). eNOS expression correlated with good glycaemic control (GGC) in the gastric corpus (p<0.001) and antrum (p=0.0037) and with absence of DAN (p=0.009 and 0.036, respectively for the corpus and antrum).

CONCLUSION

Chronic glycaemic control affects eNOS expression and angiogenesis in the gastric mucosa of patients with type 2 DM. eNOS expression is not upregulated in H. pylori-positive diabetic patients.