Ceramide and Toll-Like Receptor 4 Are Mobilized into Membrane Rafts in Response to Helicobacter pylori Infection in Gastric Epithelial Cells

ABSTRACTHelicobacter pyloriinfection is thought to be involved in the development of several gastric diseases. TwoH. pylorivirulence factors (vacuolating cytotoxin A and cytotoxin-associated gene A) reportedly interact with lipid rafts in gastric epithelial cells. The role of Toll-like receptor (TLR)-mediated signaling in response toH. pyloriinfection has been investigated extensively in host cells. However, the receptor molecules in lipid rafts that are involved inH. pylori-induced innate sensing have not been well characterized. This study investigated whether lipid rafts play a role inH. pylori-induced ceramide secretion and TLR4 expression and thereby contribute to inflammation in gastric epithelial cells. We observed that both TLR4 and MD-2 mRNA and protein levels were significantly higher inH. pylori-infected AGS cells than in mock-infected cells. Moreover, significantly more TLR4 protein was detected in detergent-resistant membranes extracted fromH. pylori-infected AGS cells than in those extracted from mock-infected cells. However, this effect was attenuated by the treatment of cells with cholesterol-usurping agents, suggesting thatH. pylori-induced TLR4 signaling is dependent on cholesterol-rich microdomains. Similarly, the level of cellular ceramide was elevated and ceramide was translocated into lipid rafts afterH. pyloriinfection, leading to interleukin-8 (IL-8) production. Using the sphingomyelinase inhibitor imipramine, we observed thatH. pylori-induced TLR4 expression was ceramide dependent. These results indicate the mobilization of ceramide and TLR4 into lipid rafts byH. pyloriinfection in response to inflammation in gastric epithelial cells.

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Epigenetic Regulation of Tumor Suppressors by Helicobacter pylori Enhances EBV-Induced Proliferation of Gastric Epithelial Cells

mBio ◽

10.1128/mbio.00649-18 ◽

2018 ◽

Vol 9 (2) ◽

Cited By ~ 8

Author(s):

Saurabh Pandey ◽

Hem Chandra Jha ◽

Sanket Kumar Shukla ◽

Meghan K. Shirley ◽

Erle S. Robertson

Keyword(s):

Helicobacter Pylori ◽

Tumor Suppressor ◽

Epithelial Cells ◽

Molecular Mechanism ◽

Tumor Suppressor Genes ◽

Model System ◽

Gastric Epithelial Cells ◽

Content Type ◽

Infected Cells ◽

H Pylori

ABSTRACT Helicobacter pylori and Epstein-Barr virus (EBV) are two well-known contributors to cancer and can establish lifelong persistent infection in the host. This leads to chronic inflammation, which also contributes to development of cancer. Association with H. pylori increases the risk of gastric carcinoma, and coexistence with EBV enhances proliferation of infected cells. Further, H. pylori -EBV coinfection causes chronic inflammation in pediatric patients. We have established an H. pylori -EBV coinfection model system using human gastric epithelial cells. We showed that H. pylori infection can increase the oncogenic phenotype of EBV-infected cells and that the cytotoxin-associated gene (CagA) protein encoded by H. pylori stimulated EBV-mediated cell proliferation in this coinfection model system. This led to increased expression of DNA methyl transferases (DNMTs), which reprogrammed cellular transcriptional profiles, including those of tumor suppressor genes (TSGs), through hypermethylation. These findings provide new insights into a molecular mechanism whereby cooperativity between two oncogenic agents leads to enhanced oncogenic activity of gastric cancer cells. IMPORTANCE We have studied the cooperativity between H. pylori and EBV, two known oncogenic agents. This led to an enhanced oncogenic phenotype in gastric epithelial cells. We now demonstrate that EBV-driven epigenetic modifications are enhanced in the presence of H. pylori , more specifically, in the presence of its CagA secretory antigen. This results in increased proliferation of the infected gastric cells. Our findings now elucidate a molecular mechanism whereby expression of cellular DNA methyl transferases is induced influencing infection by EBV. Hypermethylation of the regulatory genomic regions of tumor suppressor genes results in their silencing. This drastically affects the expression of cell cycle, apoptosis, and DNA repair genes, which dysregulates their associated processes, and promotion of the oncogenic phenotype.

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Effects ofHelicobacter pyloriand Heat Shock Protein 70 on the Proliferation of Human Gastric Epithelial Cells

Gastroenterology Research and Practice ◽

10.1155/2014/794342 ◽

2014 ◽

Vol 2014 ◽

pp. 1-5 ◽

Cited By ~ 2

Author(s):

Liping Tao ◽

Hai Zou ◽

Zhimin Huang

Keyword(s):

Helicobacter Pylori ◽

Heat Shock ◽

Epithelial Cells ◽

Heat Shock Protein ◽

Mtt Assay ◽

Heat Shock Protein 70 ◽

Hsp70 Expression ◽

Gastric Epithelial Cells ◽

Ags Cells ◽

H Pylori

Infection ofHelicobacter pylori (H. pylori)changed the proliferation of gastric epithelial cells and decreased the expression of heat shock protein 70 (HSP70). However, the effects ofH. pylorion the proliferation of gastric epithelial cells and the roles of HSP70 during the progress need further investigation.Objective.To investigate the effects ofHelicobacter pylori (H. pylori)and heat shock protein 70 (HSP70) on the proliferation of human gastric epithelial cells.Methods. H. pyloriand a human gastric epithelial cell line (AGS) were cocultured. The proliferation of AGS cells was quantitated by an MTT assay, and the expression of HSP70 in AGS cells was detected by Western blotting. HSP70 expression in AGS cells was silenced by small interfering RNA (siRNA) to investigate the role of HSP70. ThesiRNA-treated AGS cells were cocultured withH. pyloriand cell proliferation was measured by an MTT assay.Results.The proliferation of AGS cells was accelerated by coculturing withH. pylorifor 4 and 8 h, but was suppressed at 24 and 48 h. HSP70 expression was decreased in AGS cells infected byH. pylorifor 48 h. The proliferation in HSP70-silenced AGS cells was inhibited after coculturing withH. pylorifor 24 and 48 h compared with the control group.Conclusions.Coculture ofH. pylorialtered the proliferation of gastric epithelial cells and decreased HSP70 expression. HSP70 knockdown supplemented the inhibitory effect ofH. pylorion proliferation of epithelial cells. These results indicate that the effects ofH. pylorion the proliferation of gastric epithelial cells at least partially depend on the decreased expression of HSP70 induced by the bacterium.

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Helicobacter pylori Induces Gastric Epithelial Cell Apoptosis in Association with Increased Fas Receptor Expression

Infection and Immunity ◽

10.1128/iai.67.8.4237-4242.1999 ◽

1999 ◽

Vol 67 (8) ◽

pp. 4237-4242 ◽

Cited By ~ 106

Author(s):

Nicola L. Jones ◽

Andrew S. Day ◽

Hilary A. Jennings ◽

Philip M. Sherman

Keyword(s):

Cell Death ◽

Helicobacter Pylori ◽

Epithelial Cells ◽

Receptor Expression ◽

Gastric Epithelial Cells ◽

Ags Cells ◽

Fas Receptor ◽

Epithelial Cell Apoptosis ◽

H Pylori

ABSTRACT The mechanisms involved in mediating the enhanced gastric epithelial cell apoptosis observed during infection withHelicobacter pylori in vivo are unknown. To determine whether H. pylori directly induces apoptosis of gastric epithelial cells in vitro and to define the role of the Fas-Fas ligand signal transduction cascade, human gastric epithelial cells were infected with H. pylori for up to 72 h under microaerophilic conditions. As assessed by both transmission electron microscopy and fluorescence microscopy, incubation with acagA-positive, cagE-positive, VacA-positive clinical H. pylori isolate stimulated an increase in apoptosis compared to the apoptosis of untreated AGS cells (16.0% ± 2.8% versus 5.9% ± 1.4%, P < 0.05) after 72 h. In contrast, apoptosis was not detected following infection withcagA-negative, cagE-negative, VacA-negative clinical isolates or a Campylobacter jejuni strain. In addition to stimulating apoptosis, infection with H. pylorienhanced Fas receptor expression in AGS cells to a degree comparable to that of treatment with a positive control, gamma interferon (12.5 ng/ml) (148% ± 24% and 167% ± 24% of control, respectively). The enhanced Fas receptor expression was associated with increased sensitivity to Fas-mediated cell death. Ligation of the Fas receptor with an agonistic monoclonal antibody resulted in an increase in apoptosis compared to the apoptosis of cells infected with the bacterium alone (38.5% ± 7.1% versus 16.0% ± 2.8%,P < 0.05). Incubation with neutralizing anti-Fas antibody did not prevent apoptosis of H. pylori-infected cells. Taken together, these findings demonstrate that the gastric pathogen H. pylori stimulates apoptosis of gastric epithelial cells in vitro in association with the enhanced expression of the Fas receptor. These data indicate a role for Fas-mediated signaling in the programmed cell death that occurs in response toH. pylori infection.

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Lactobacillus fermentum UCO-979C beneficially modulates the innate immune response triggered by Helicobacter pylori infection in vitro

Beneficial Microbes ◽

10.3920/bm2018.0019 ◽

2018 ◽

Vol 9 (5) ◽

pp. 829-841 ◽

Cited By ~ 7

Author(s):

V. Garcia-Castillo ◽

H. Zelaya ◽

A. Ilabaca ◽

M. Espinoza-Monje ◽

R. Komatsu ◽

...

Keyword(s):

Immune Response ◽

Helicobacter Pylori ◽

Epithelial Cells ◽

Morphological Changes ◽

Helicobacter Pylori Infection ◽

Lactobacillus Fermentum ◽

Gastric Tissue ◽

Gastric Epithelial Cells ◽

Ags Cells ◽

H Pylori

Helicobacter pylori infection is associated with important gastric pathologies. An aggressive proinflammatory immune response is generated in the gastric tissue infected with H. pylori, resulting in gastritis and a series of morphological changes that increase the susceptibility to cancer development. Probiotics could present an alternative solution to prevent or decrease H. pylori infection. Among them, the use of immunomodulatory lactic acid bacteria represents a promising option to reduce the severity of chronic inflammatory-mediated tissue damage and to improve protective immunity against H. pylori. We previously isolated Lactobacillus fermentum UCO-979C from human gastric tissue and demonstrated its capacity to reduce adhesion of H. pylori to human gastric epithelial cells (AGS cells). In this work, the ability of L. fermentum UCO-979C to modulate immune response in AGS cells and PMA phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 (human monocytic leukaemia) macrophages in response to H. pylori infection was evaluated. We demonstrated that the UCO-979C strain is able to differentially modulate the cytokine response of gastric epithelial cells and macrophages after H. pylori infection. Of note, L. fermentum UCO-979C was able to significantly reduce the production of inflammatory cytokines and chemokines in AGS and THP-1 cells as well as increase the levels of immunoregulatory cytokines, indicating a remarkable anti-inflammatory effect. These findings strongly support the probiotic potential of L. fermentum UCO-979C and provide evidence of its beneficial effects against the inflammatory damage induced by H. pylori infection. Although our findings should be proven in appropriate experiments in vivo, in both H. pylori infection animal models and human trials, the results of the present work provide a scientific rationale for the use of L. fermentum UCO-979C to prevent or reduce H. pylori-induced gastric inflammation in humans.

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Helicobacter pylori induces intracellular galectin-8 aggregation around damaged lysosomes within gastric epithelial cells in a host O-glycan-dependent manner

Glycobiology ◽

10.1093/glycob/cwy095 ◽

2018 ◽

Vol 29 (2) ◽

pp. 151-162 ◽

Cited By ~ 6

Author(s):

Fang-Yen Li ◽

I-Chun Weng ◽

Chun-Hung Lin ◽

Mou-Chieh Kao ◽

Ming-Shiang Wu ◽

...

Keyword(s):

Helicobacter Pylori ◽

Epithelial Cells ◽

Rhesus Macaques ◽

Dependent Manner ◽

Gastric Epithelial Cells ◽

Vacuolating Cytotoxin ◽

Infected Cells ◽

H Pylori ◽

Autophagy Activity ◽

Binding Lectin

Abstract Galectin-8, a beta-galactoside-binding lectin, is upregulated in the gastric tissues of rhesus macaques infected with Helicobacter pylori. In this study, we found that H. pylori infection triggers intracellular galectin-8 aggregation in human-derived AGS gastric epithelial cells, and that these aggregates colocalize with lysosomes. Notably, this aggregation is markedly reduced following the attenuation of host O-glycan processing. This indicates that H. pylori infection induces lysosomal damage, which in turn results in the accumulation of cytosolic galectin-8 around damaged lysosomes through the recognition of exposed vacuolar host O-glycans. H. pylori-induced galectin-8 aggregates also colocalize with autophagosomes, and galectin-8 ablation reduces the activation of autophagy by H. pylori. This suggests that galectin-8 aggregates may enhance autophagy activity in infected cells. We also observed that both autophagy and NDP52, an autophagy adapter, contribute to the augmentation of galectin-8 aggregation by H. pylori. Additionally, vacuolating cytotoxin A, a secreted H. pylori cytotoxin, may contribute to the increased galectin-8 aggregation and elevated autophagy response in infected cells. Collectively, these results suggest that H. pylori promotes intracellular galectin-8 aggregation, and that galectin-8 aggregation and autophagy may reciprocally regulate each other during infection.

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Inhibitory Effect of β-Carotene on Helicobacter pylori-Induced TRAF Expression and Hyper-Proliferation in Gastric Epithelial Cells

Antioxidants ◽

10.3390/antiox8120637 ◽

2019 ◽

Vol 8 (12) ◽

pp. 637 ◽

Cited By ~ 2

Author(s):

Yongchae Park ◽

Hanbit Lee ◽

Joo Weon Lim ◽

Hyeyoung Kim

Keyword(s):

Gene Expression ◽

Gastric Cancer ◽

Helicobacter Pylori ◽

Epithelial Cells ◽

Nadph Oxidase ◽

Gastric Epithelial Cells ◽

Gastric Cancer Cells ◽

Ags Cells ◽

H Pylori ◽

Β Carotene

Helicobacter pylori infection causes the hyper-proliferation of gastric epithelial cells that leads to the development of gastric cancer. Overexpression of tumor necrosis factor receptor associated factor (TRAF) is shown in gastric cancer cells. The dietary antioxidant β-carotene has been shown to counter hyper-proliferation in H. pylori-infected gastric epithelial cells. The present study was carried out to examine the β-carotene mechanism of action. We first showed that H. pylori infection decreases cellular IκBα levels while increasing cell viability, NADPH oxidase activity, reactive oxygen species production, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation, and TRAF1 and TRAF2 gene expression, as well as protein–protein interaction in gastric epithelial AGS cells. We then demonstrated that pretreatment of cells with β-carotene significantly attenuates these effects. Our findings support the proposal that β-carotene has anti-cancer activity by reducing NADPH oxidase-mediated production of ROS, NF-κB activation and NF-κB-regulated TRAF1 and TRAF2 gene expression, and hyper-proliferation in AGS cells. We suggest that the consumption of β-carotene-enriched foods could decrease the incidence of H. pylori-associated gastric disorders.

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α-Lipoic Acid Inhibits IL-8 Expression by Activating Nrf2 Signaling in Helicobacter pylori-infected Gastric Epithelial Cells

Nutrients ◽

10.3390/nu11102524 ◽

2019 ◽

Vol 11 (10) ◽

pp. 2524 ◽

Cited By ~ 3

Author(s):

Seoyeon Kyung ◽

Joo Weon Lim ◽

Hyeyoung Kim

Keyword(s):

Oxidative Stress ◽

Helicobacter Pylori ◽

Epithelial Cells ◽

Lipoic Acid ◽

Heme Oxygenase 1 ◽

Related Factor ◽

Gastric Epithelial Cells ◽

Gastric Diseases ◽

Ags Cells ◽

H Pylori

Helicobacter pylori (H. pylori) causes gastritis and gastric cancers. Oxidative stress is involved in the pathological mechanism of H. pylori-induced gastritis and gastric cancer induction. Therefore, reducing oxidative stress may be beneficial for preventing the development of H. pylori-associated gastric diseases. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a crucial regulator for the expression of antioxidant enzyme heme oxygenase-1 (HO-1), which protects cells from oxidative injury. α-Lipoic acid (α-LA), a naturally occurring dithiol, shows antioxidant and anti-inflammatory effects in various cells. In the present study, we examined the mechanism by which α-LA activates the Nrf2/HO-1 pathway, suppresses the production of pro-inflammatory cytokine interleukine-8 (IL-8), and reduces reactive oxygen species (ROS) in H. pylori-infected AGS cells. α-LA increased the level of phosphorylated and nuclear-translocated Nrf2 by decreasing the amount of Nrf2 sequestered in the cytoplasm by complex formation with Kelch-like ECH1-associated protein 1 (KEAP 1). By using exogenous inhibitors targeting Nrf2 and HO-1, we showed that up-regulation of activated Nrf2 and of HO-1 results in the α-LA-induced suppression of interleukin 8 (IL-8) and ROS. Consumption of α-LA-rich foods may prevent the development of H. pylori-associated gastric diseases by decreasing ROS-mediated IL-8 expression in gastric epithelial cells.

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Phylogeographic Origin of Helicobacter pylori Determines Host-Adaptive Responses upon Coculture with Gastric Epithelial Cells

Infection and Immunity ◽

10.1128/iai.01182-12 ◽

2013 ◽

Vol 81 (7) ◽

pp. 2468-2477 ◽

Cited By ~ 16

Author(s):

Alexander Sheh ◽

Rupesh Chaturvedi ◽

D. Scott Merrell ◽

Pelayo Correa ◽

Keith T. Wilson ◽

...

Keyword(s):

Gene Expression ◽

Gastric Cancer ◽

Helicobacter Pylori ◽

Epithelial Cells ◽

Gastric Disease ◽

Gastric Epithelial Cells ◽

Gastric Cancer Risk ◽

Content Type ◽

H Pylori ◽

Induced Apoptosis

ABSTRACTWhileHelicobacter pyloriinfects over 50% of the world's population, the mechanisms involved in the development of gastric disease are not fully understood. Bacterial, host, and environmental factors play a role in disease outcome. To investigate the role of bacterial factors inH. pyloripathogenesis, global gene expression of sixH. pyloriisolates was analyzed during coculture with gastric epithelial cells. Clustering analysis of six Colombian clinical isolates from a region with low gastric cancer risk and a region with high gastric cancer risk segregated strains based on their phylogeographic origin. One hundred forty-six genes had increased expression in European strains, while 350 genes had increased expression in African strains. Differential expression was observed in genes associated with motility, pathogenicity, and other adaptations to the host environment. European strains had greater expression of the virulence factorscagA,vacA, andbabBand were associated with increased gastric histologic lesions in patients. In AGS cells, European strains promoted significantly higher interleukin-8 (IL-8) expression than did African strains. African strains significantly induced apoptosis, whereas only one European strain significantly induced apoptosis. Our data suggest that gene expression profiles of clinical isolates can discriminate strains by phylogeographic origin and that these profiles are associated with changes in expression of the proinflammatory and protumorigenic cytokine IL-8 and levels of apoptosis in host epithelial cells. These findings support the hypothesis that bacterial factors determined by the phylogeographic origin ofH. pyloristrains may promote increased gastric disease.

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Anti-Inflammatory Mechanism of Polyunsaturated Fatty Acids inHelicobacter pylori-Infected Gastric Epithelial Cells

Mediators of Inflammation ◽

10.1155/2014/128919 ◽

2014 ◽

Vol 2014 ◽

pp. 1-12 ◽

Cited By ~ 16

Author(s):

Sun Eun Lee ◽

Joo Weon Lim ◽

Jung Mogg Kim ◽

Hyeyoung Kim

Keyword(s):

Fatty Acids ◽

Epithelial Cells ◽

Polyunsaturated Fatty Acids ◽

Growth Factor Receptor ◽

Inhibitory Effect ◽

Gastric Epithelial Cells ◽

Alpha Linolenic Acid ◽

Ags Cells ◽

Infected Cells ◽

H Pylori

Helicobacter pyloriis an important risk factor for gastric inflammation, which is mediated by multiple signaling pathways. The aim of this study was to investigate the effects of polyunsaturated fatty acids (PUFAs), such as linoleic acid (LA), alpha-linolenic acid (ALA), and docosahexaenoic acid (DHA), on the expression of the proinflammatory chemokine interleukin-8 (IL-8) inH. pylori-infected gastric epithelial AGS cells. To investigate whether PUFAs modulateH. pylori-induced inflammatory signaling, we determined the activation of epidermal growth factor receptor (EGFR), protein kinase C-δ(PKCδ), mitogen-activated protein kinases (MAPKs), nuclear factor-kappa B (NF-κB), and activator protein-1 (AP-1) as well as IL-8 expression inH. pylori-infected gastric epithelial cells that had been treated with or without PUFAs. We found that PUFAs inhibited IL-8 mRNA and protein expression inH. pylori-infected cells.ω-3 fatty acids (ALA, and DHA) suppressed the activation of EGFR, PKCδ, MAPK, NF-κB, and AP-1 in these infected cells. LA did not prevent EGFR transactivation and exhibited a less potent inhibitory effect on IL-8 expression than did ALA and DHA. In conclusion, PUFAs may be beneficial for prevention ofH. pylori-associated gastric inflammation by inhibiting proinflammatory IL-8 expression.

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Chemokines and Antimicrobial Peptides Have acag-Dependent Early Response to Helicobacter pylori Infection in Primary Human Gastric Epithelial Cells

Infection and Immunity ◽

10.1128/iai.01517-13 ◽

2014 ◽

Vol 82 (7) ◽

pp. 2881-2889 ◽

Cited By ~ 19

Author(s):

Pascale Mustapha ◽

Isabelle Paris ◽

Magali Garcia ◽

Cong Tri Tran ◽

Julie Cremniter ◽

...

Keyword(s):

Helicobacter Pylori ◽

Epithelial Cells ◽

Inflammatory Response ◽

Antimicrobial Peptides ◽

Virulence Factors ◽

Inflammatory Mediator ◽

Host Cells ◽

Gastric Epithelial Cells ◽

Content Type ◽

H Pylori

ABSTRACTHelicobacter pyloriinfection systematically causes chronic gastric inflammation that can persist asymptomatically or evolve toward more severe gastroduodenal pathologies, such as ulcer, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric cancer. Thecagpathogenicity island (cagPAI) ofH. pyloriallows translocation of the virulence protein CagA and fragments of peptidoglycan into host cells, thereby inducing production of chemokines, cytokines, and antimicrobial peptides. In order to characterize the inflammatory response toH. pylori, a new experimental protocol for isolating and culturing primary human gastric epithelial cells was established using pieces of stomach from patients who had undergone sleeve gastrectomy. Isolated cells expressed markers indicating that they were mucin-secreting epithelial cells. Challenge of primary epithelial cells withH. pyloriB128 underscored early dose-dependent induction of expression of mRNAs of the inflammatory mediators CXCL1 to -3, CXCL5, CXCL8, CCL20, BD2, and tumor necrosis factor alpha (TNF-α). In AGS cells, significant expression of only CXCL5 and CXCL8 was observed following infection, suggesting that these cells were less reactive than primary epithelial cells. Infection of both cellular models withH. pyloriB128ΔcagM, acagPAI mutant, resulted in weak inflammatory-mediator mRNA induction. At 24 h after infection of primary epithelial cells withH. pylori, inflammatory-mediator production was largely due tocagPAI substrate-independent virulence factors. Thus,H. pyloricagPAI substrate appears to be involved in eliciting an epithelial response during the early phases of infection. Afterwards, other virulence factors of the bacterium take over in development of the inflammatory response. Using a relevant cellular model, this study provides new information on the modulation of inflammation duringH. pyloriinfection.

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