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Cholesteryl α-D-glucoside 6-acyltransferase enhances the adhesion of Helicobacter pylori to gastric epithelium.

ABSTRACT: Helicobacter pylori, the most common etiologic agent of gastric diseases including gastric cancer, is auxotrophic for cholesterol and has to hijack it from gastric epithelia. Upon uptake, the bacteria convert cholesterol to cholesteryl 6'-O-acyl-α-D-glucopyranoside (CAG) to promote lipid raft clustering in the host cell membranes. However, how CAG appears in the host to exert the pathogenesis still remains ambiguous. Herein we identified hp0499 to be the gene of cholesteryl α-D-glucopyranoside acyltransferase (CGAT). Together with cholesteryl glucosyltransferase (catalyzing the prior step), CGAT is secreted via outer membrane vesicles to the host cells for direct synthesis of CAG. This significantly enhances lipid rafts clustering, gathers adhesion molecules (including Lewis antigens and integrins α5, β1), and promotes more bacterial adhesion. Furthermore, the clinically used drug amiodarone was shown as a potent inhibitor of CGAT to effectively reduce the bacterial adhesion, indicating that CGAT is a potential target of therapeutic intervention.

SUBMITTER: Jan HM

PROVIDER: S-EPMC7069968 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Cholesteryl α-D-glucoside 6-acyltransferase enhances the adhesion of Helicobacter pylori to gastric epithelium

Project description:Cellular locations of (Cholesteryl α-D-glucoside 6-acyltransferase) CGAT To study the cellular location of CGAT, based on our pervious experiments, the CGAT activity was observed in the outer membrane vesicles (OMVs), rather than in the culture medium, suggesting that CGAT resided in the outer membrane can be enclosed in the OMVs and secreted to the extracellular space. We then performed proteomic analysis for OMVs. Based on proteomic analysis, we found CGAT was present in the OMVs isolated from the strains of H. pylori 26695 and ΔCGT-knock-out, instead of ΔCGAT-knock-out strain.

2020-03-19 | PXD017518 | Pride

Helicobacter pylori infection induces interleukin-8 receptor expression in the human gastric epithelium.

Project description:The gastric pathogen Helicobacter pylori is known to activate multiple proinflammatory signaling pathways in epithelial cells. In this study, we addressed the question of whether expression of the interleukin-8 receptors IL-8RA (CXCR1) and IL-8RB (CXCR2) is upregulated in H. pylori-infected human gastric biopsy samples. Biopsy samples from patients infected with H. pylori strains harboring the cag pathogenicity island (PAI) expressed larger amounts of both receptors. In addition, IL-8RB expression was induced in the gastric epithelial cell line AGS upon infection with a clinical isolate containing the cag PAI, while a strain lacking the cag PAI did not. Our finding suggests that gastric epithelial cells express IL-8R in response to H. pylori infection.

| S-EPMC155779 | biostudies-literature

Helicobacter pylori cholesteryl α-glucosides contribute to its pathogenicity and immune response by natural killer T cells.

Project description:Approximately 10-15% of individuals infected with Helicobacter pylori will develop ulcer disease (gastric or duodenal ulcer), while most people infected with H. pylori will be asymptomatic. The majority of infected individuals remain asymptomatic partly due to the inhibition of synthesis of cholesteryl α-glucosides in H. pylori cell wall by α1,4-GlcNAc-capped mucin O-glycans, which are expressed in the deeper portion of gastric mucosa. However, it has not been determined how cholesteryl α-glucosyltransferase (αCgT), which forms cholesteryl α-glucosides, functions in the pathogenesis of H. pylori infection. Here, we show that the activity of αCgT from H. pylori clinical isolates is highly correlated with the degree of gastric atrophy. We investigated the role of cholesteryl α-glucosides in various aspects of the immune response. Phagocytosis and activation of dendritic cells were observed at similar degrees in the presence of wild-type H. pylori or variants harboring mutant forms of αCgT showing a range of enzymatic activity. However, cholesteryl α-glucosides were recognized by invariant natural killer T (iNKT) cells, eliciting an immune response in vitro and in vivo. Following inoculation of H. pylori harboring highly active αCgT into iNKT cell-deficient (Jα18(-/-)) or wild-type mice, bacterial recovery significantly increased in Jα18(-/-) compared to wild-type mice. Moreover, cytokine production characteristic of Th1 and Th2 cells dramatically decreased in Jα18(-/-) compared to wild-type mice. These findings demonstrate that cholesteryl α-glucosides play critical roles in H. pylori-mediated gastric inflammation and precancerous atrophic gastritis.

| S-EPMC3846475 | biostudies-literature

Transient receptor potential vanilloid 4 (TRPV4) silencing in Helicobacter pylori-infected human gastric epithelium.

Project description:Helicobacter pylori (HP) infection induces methylation silencing of specific genes in gastric epithelium. Various stimuli activate the nonselective cation channel TRPV4, which is expressed in gastric epithelium where it detects mechanical stimuli and promotes ATP release. As CpG islands in TRPV4 are methylated in HP-infected gastric epithelium, we evaluated HP infection-dependent changes in TRPV4 expression in gastric epithelium. Human gastric biopsy samples, a human gastric cancer cell line (AGS), and a normal gastric epithelial cell line (GES-1) were used to detect TRPV4 mRNA and protein expression by RT-PCR and Western blotting, respectively. Ca2+ imaging was used to evaluate TRPV4 ion channel activity. TRPV4 methylation status was assessed by methylation-specific PCR (MSP). ATP release was measured by a luciferin-luciferase assay. TRPV4 mRNA and protein were detected in human gastric biopsy samples and in GES-1 cells. MSP and demethylation assays showed TRPV4 methylation silencing in AGS cells. HP coculture directly induced methylation silencing of TRPV4 in GES-1 cells. In human samples, HP infection was associated with TRPV4 methylation silencing that recovered after HP eradication in a time-dependent manner. HP infection-dependent DNA methylation suppressed TRPV4 expression in human gastric epithelia, suggesting that TRPV4 methylation may be involved in HP-associated dyspepsia.

| S-EPMC5363345 | biostudies-literature

Helicobacter pylori in gastric carcinogenesis.

Project description:Gastric cancer still is a major concern as the third most common cancer worldwide, despite declining rates of incidence in many Western countries. Helicobacter pylori (H. pylori) is the major cause of gastric carcinogenesis, and its infection insults gastric mucosa leading to the occurrence of atrophic gastritis which progress to intestinal metaplasia, dysplasia, early gastric cancer, and advanced gastric cancer consequently. This review focuses on multiple factors including microbial virulence factors, host genetic factors, and environmental factors, which can heighten the chance of occurrence of gastric adenocarcinoma due to H. pylori infection. Bacterial virulence factors are key components in controlling the immune response associated with the induction of carcinogenesis, and cagA and vacA are the most well-known pathogenic factors. Host genetic polymorphisms contribute to regulating the inflammatory response to H. pylori and will become increasingly important with advancing techniques. Environmental factors such as high salt and smoking may also play a role in gastric carcinogenesis. It is important to understand the virulence factors, host genetic factors, and environmental factors interacting in the multistep process of gastric carcinogenesis. To conclude, prevention via H. pylori eradication and controlling environmental factors such as diet, smoking, and alcohol is an important strategy to avoid H. pylori-associated gastric carcinogenesis.

| S-EPMC4678392 | biostudies-literature

Vacuolating Cytotoxin A Triggers Mitophagy in <i>Helicobacter pylori</i>-Infected Human Gastric Epithelium Cells.

Project description:Helicobacter pylori (H. pylori)-derived vacuolating cytotoxin A (VacA) causes damage to various organelles, including mitochondria, and induces autophagy and cell death. However, it is unknown whether VacA-induced mitochondrial damage can develop into mitophagy. In this study, we found that H. pylori, H. pylori culture filtrate (HPCF), and VacA could activate autophagy in a gastric epithelial cell line (GES-1). VacA-caused mitochondrial depolarization retards the import of PINK1 into the damaged mitochondria and evokes mitophagy. And, among mass spectrometry (LC-MS/MS) identified 25 mitochondrial proteins bound with VacA, Tom20, Tom40, and Tom70, TOM complexes responsible for PINK1 import, were further identified as having the ability to bind VacA in vitro using pull-down assay, co-immunoprecipitation, and protein-protein docking. Additionally, we found that the cell membrane protein STOM and the mitochondrial inner membrane protein PGAM5 also interacted with VacA. These findings suggest that VacA captured by STOM forms endosomes to enter cells and target mitochondria. Then, VacA is transported into the mitochondrial membrane space through the TOM complexes, and PGAM5 aids in inserting VacA into the inner mitochondrial membrane to destroy the membrane potential, which promotes PINK1 accumulation and Parkin recruitment to induce mitophagy. This study helps us understand VacA entering mitochondria to induce the mitophagy process.

| S-EPMC9329568 | biostudies-literature

Helicobacter pylori Colonization Drives Urokinase Receptor (uPAR) Expression in Murine Gastric Epithelium During Early Pathogenesis.

Project description:(1) Background: Persistent Helicobacter pylori infection is the most important risk factor for gastric cancer. The urokinase receptor (uPAR) is upregulated in lesions harboring cancer invasion and inflammation. Circumstantial evidence tends to correlate H. pylori colonization with increased uPAR expression in the human gastric epithelium, but a direct causative link has not yet been established in vivo; (2) Methods: In a mouse model of H. pylori-induced gastritis, we investigated the temporal emergence of uPAR protein expression in the gastric mucosa in response to H. pylori (SS1 strain) infection; (3) Results: We observed intense uPAR immunoreactivity in foveolar epithelial cells of the gastric corpus due to de novo synthesis, compared to non-infected animals. This uPAR induction represents a very early response, but it increases progressively over time as do infiltrating immune cells. Eradication of H. pylori infection by antimicrobial therapy causes a regression of uPAR expression to its physiological baseline levels. Suppression of the inflammatory response by prostaglandin E2 treatment attenuates uPAR expression. Notwithstanding this relationship, H. pylori does induce uPAR expression in vitro in co-cultures with gastric cancer cell lines; (4) Conclusions: We showed that persistent H. pylori colonization is a necessary event for the emergence of a relatively high uPAR protein expression in murine gastric epithelial cells.

| S-EPMC7409347 | biostudies-literature

Helicobacter pylori infection dysregulates gastric proteome

Project description:The purpose of the study was to define gastric cell-specific proteomic changes, induced by H. pylori oncogenic strains, that are critical for initiation of the gastric carcinogenic cascade. Gastric cell scrapings were harvested from H. pylori-infected and uninfected animals for quantitative proteomic analyses using isobaric tags for relative and absolute quantitation (iTRAQ). Canonical and disease pathway mapping using Ingenuity Pathway Analysis (IPA) identified significantly altered inflammatory and cancer-signaling pathways that included Rab/Ras signaling proteins.

2018-11-23 | PXD009583 | Pride

Essential role of Helicobacter pylori apolipoprotein N-acyltransferase (Lnt) in stomach colonization

Project description:Deleting lnt changes the number of acyl chains on lipoproteins and the number of acyl chains on lipoproteins impacts the innate immune response through TLR2 signaling. We treated primary human gastric epithelial cells with a purified lipoprotein from wild-type or lnt mutant H. pylori and performed RNAseq. Differential gene expression analysis indicated lipoprotein from the lnt mutant induced a more robust TLR2 response.

2023-10-17 | GSE241938 | GEO

Genomic landscape of epithelium with low-grade atypia on gastric cancer after Helicobacter pylori eradiation therapy.

Project description:BACKGROUND:Gastric cancer may develop after successful eradication of Helicobacter pylori, although the incidence is lower than in non-eradicated individuals. We previously reported the appearance of characteristic epithelium with low-grade atypia (ELA) on the surface of gastric cancer after H. pylori eradication. However, whether ELA originates from cancer after re-differentiation or from the non-cancerous surrounding mucosa is unknown. METHODS:We isolated ELA regions from 10 early gastric cancer patients and analyzed the nucleotide sequences for 90 oncogenes and 35 fusion oncogenes, comparing them with counterpart cancer tissue, normal gastric mucosa, and blood cell-derived DNA. Somatic mutations in each tissue were identified by comparing them with the sequences from whole blood-derived DNA. RESULT:Gene alterations were observed in nine of the ten patients, and up to 42 and 70 somatic mutations were seen in cancer and ELA samples, respectively. Common mutations shared between cancer and ELA tissues were found in eight of these nine patients. In contrast, common mutations between non-cancer mucosa and ELA were only detected in one patient, who also had common mutation between cancer and ELA. ELA-specific nucleotide substitutions were seen in seven patients. In contrast, cancer-specific substitutions were only found in two patients. 18 out of 19 amino acid substitutions present in cancer tissue were also identified in ELA. These results suggest that ELA originated from cancer tissue and accumulated further nucleotide substitutions. CONCLUSIONS:Differential diagnosis of ELA and normal mucosa should be carefully performed to prevent misdiagnosis of ELA as normal mucosa with atypia.

| S-EPMC6759680 | biostudies-literature

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