Helicobacter pylori pathogen inhibits cellular responses to oncogenic stress and apoptosis.
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ABSTRACT:
SUBMITTER: Palrasu M
PROVIDER: S-EPMC9242521 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Vacuolating cytotoxin A (VacA) is one of the important virulence factors produced by H. pylori. VacA induces apoptotic cell death, which is potentiated by ammonia. VacA also causes cell death by mitochondrial damage, via signaling pathways that are not fully defined. Our aim was to determine whether endoplasmic reticulum (ER) stress is associated with VacA-induced mitochondrial dysfunction and apoptosis. We found that C/EBP homologous protein (CHOP), a key signaling protein of ER stress-induced apoptosis, was transcriptionally up-regulated following incubation of gastric epithelial cells with VacA. The effect of VacA on CHOP induction was significantly enhanced by co-incubation with ammonium chloride. Phosphorylation of eukaryotic initiation factor 2 (eIF2)-alpha, which is known to occur downstream of the ER stress sensor PKR-like ER-localized eIF2-alpha kinase (PERK) and to regulate CHOP expression, was also observed following incubation with VacA in the presence of ammonium chloride. Knockdown of CHOP by siRNA resulted in inhibition of VacA-induced apoptosis. Further studies showed that silencing of the PERK gene with siRNA attenuated VacA-mediated phosphorylation of eIF2-alpha, CHOP induction, expression of BH3-only protein Bim and Bax activation, and cell death induced by VacA with ammonium chloride, indicating that ER stress may lead to mitochondrial dysfunction during VacA-induced toxicity. Activation of ER stress and up-regulation of BH3-only proteins were also observed in human H. pylori-infected gastric mucosa. Collectively, this study reveals a possible association between VacA-induced apoptosis in gastric epithelial cells, and activation of ER stress in H. pylori-positive gastric mucosa.
| S-EPMC3862672 | biostudies-literature
Project description:Helicobacter pylori (H. pylori) classified as a class I carcinogen by the World Health Organization (WHO) plays an important role in the progression of chronic gastritis and the development of gastric cancer. A major bioactive component of Evodia rutaecarpa, evodiamine, has been known for its anti-bacterial effect and anti-cancer effects. However, the inhibitory effect of evodiamine against H. pylori is not yet known and the inhibitory mechanisms of evodiamine against gastric cancer cells are yet to be elucidated concretely. In this study, therefore, anti-bacterial effect of evodiamine on H. pylori growth and its inhibitory mechanisms as well as anti-inflammatory effects and its mechanisms of evodiamine on H. pylori-induced inflammation were investigated in vitr. Results of this study showed the growth of the H. pylori reference strains and clinical isolates were inhibited by evodiamine. It was considered one of the inhibitory mechanisms that evodiamine downregulated both gene expressions of replication and transcription machineries of H. pylori. Treatment of evodiamine also induced downregulation of urease and diminished translocation of cytotoxin-associated antigen A (CagA) and vacuolating cytotoxin A (VacA) proteins into gastric adenocarcinoma (AGS) cells. This may be resulted from the reduction of CagA and VacA expressions as well as the type IV secretion system (T4SS) components and secretion system subunit protein A (SecA) protein which are involved in translocation of CagA and VacA into host cells, respectively. In particular, evodiamine inhibited the activation of signaling proteins such as the nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) and the mitogen-activated protein kinase (MAPK) pathway induced by H. pylori infection. It consequently might contribute to reduction of interleukin (IL)-8 production in AGS cells. Collectively, these results suggest anti-bacterial and anti-inflammatory effects of evodiamine against H. pylori.
| S-EPMC8036659 | biostudies-literature
Project description:Helicobacter pylori (H. pylori) is the strongest known risk for gastric cancer. The H. pylori cag type IV secretion system is an oncogenic locus that translocates peptidoglycan into host cells, where it is recognized by NOD1, an innate immune receptor. Beyond this, the role of NOD1 in H. pylori-induced cancer remains undefined. To address this knowledge gap, we infected two genetic models of Nod1 deficiency with the H. pylori cag + strain PMSS1: C57BL/6 mice, which rarely develop cancer, and INS-GAS FVB/N mice, which commonly develop cancer. Infected C57BL/6 Nod1-/- and INS-GAS Nod1-/- mice acutely developed more severe gastritis, and INS-GAS Nod1-/- mice developed gastric dysplasia more frequently compared with Nod1+/+ mice. Because Nod1 genotype status did not alter microbial phenotypes of in vivo-adapted H. pylori, we investigated host immunologic responses. H. pylori infection of Nod1-/- mice led to significantly increased gastric mucosal levels of Th1, Th17, and Th2 cytokines compared with Nod1 wild-type (WT) mice. To define the role of specific innate immune cells, we quantified cytokine secretion from H. pylori-infected primary gastric organoids generated from WT or Nod1-/- mice that were cocultured with or without WT or Nod1-/- macrophages. Infection increased cytokine production from gastric epithelial cells and macrophages and elevations were significantly increased with Nod1 deficiency. Furthermore, H. pylori infection altered the polarization status of Nod1-/- macrophages compared with Nod1+/+ macrophages. Collectively, these studies demonstrate that loss of Nod1 augments inflammatory and injury responses to H. pylori. Nod1 may exert its restrictive role by altering macrophage polarization, leading to immune evasion and microbial persistence. SIGNIFICANCE: These findings suggest that manipulation of NOD1 may represent a novel strategy to prevent or treat pathologic outcomes induced by H. pylori infection.
| S-EPMC6445772 | biostudies-literature
Project description:The mitogen-activated protein kinase (MAPK) signaling pathway regulates various cellular functions, including those induced by Helicobacter pylori. TAK1 is an upstream MAPK kinase kinase (MAP3K) required for H. pylori-induced MAPK and NF-κB activation, but it remains unclear whether other MAP3Ks are involved in H. pylori-induced cellular responses. In this study, we focused on the MAP3K ASK1, which plays a critical role in gastric tumorigenesis. In gastric epithelial cells, H. pylori activates ASK1 in a reactive oxygen species (ROS)- and cag pathogenicity island-dependent manner, and ASK1 regulates sustained JNK activation and apoptosis induced by H. pylori. In contrast, TAK1 regulates H. pylori-mediated early JNK activation and cytokine production. We also found reciprocal regulation between ASK1 and TAK1 in H. pylori-related responses, whereby inhibition of TAK1 or downstream p38 MAPK activates ASK1 through ROS production, and ASK1 suppresses TAK1 and downstream NF-κB activation. We identified ROS/ASK1/JNK as a new signaling pathway induced by H. pylori, which regulates apoptotic cell death. The balance of ASK1-induced apoptosis and TAK1-induced antiapoptotic or inflammatory responses may determine the fate of epithelial cells infected with H. pylori and thus be involved in the pathogenesis of gastritis and gastric cancer.
| S-EPMC3837986 | biostudies-literature
Project description:Helicobacter pylori (H. pylori) produces urease in order to improve its settlement and growth in the human gastric epithelium. Urease inhibitors likely represent potentially powerful therapeutics for treating H. pylori; however, their instability and toxicity have proven problematic in human clinical trials. In this study, we investigate the ability of a natural compound extracted from Zingiber zerumbet Smith, zerumbone, to inhibit the urease activity of H. pylori by formation of urease dimers, trimers, or tetramers. As an oxygen atom possesses stronger electronegativity than the first carbon atom bonded to it, in the zerumbone structure, the neighboring second carbon atom shows a relatively negative charge (δ-) and the next carbon atom shows a positive charge (δ+), sequentially. Due to this electrical gradient, it is possible that H. pylori urease with its negative charges (such as thiol radicals) might bind to the β-position carbon of zerumbone. Our results show that zerumbone dimerized, trimerized, or tetramerized with both H. pylori urease A and urease B molecules, and that this formation of complex inhibited H. pylori urease activity. Although zerumbone did not affect either gene transcription or the protein expression of urease A and urease B, our study demonstrated that zerumbone could effectively dimerize with both urease molecules and caused significant functional inhibition of urease activity. In short, our findings suggest that zerumbone may be an effective H. pylori urease inhibitor that may be suitable for therapeutic use in humans.
| S-EPMC8124612 | biostudies-literature
Project description:The purpose of this study was to examine macrophage proteomic changes induced by Helicobacter pylori. Macrophages utilized were the RAW 264.7 murine cell line. Macrophages were treated with H. pylori for 24 hours. The experimental design was a 4-plex isobaric tags for relative and absolute quantification (iTRAQ). In addition to uninfected control and H. pylori infected, the additional two conditions included an inhibitor of deoxyhypusine synthase (N1-guanyl-1,7-diamine-heptane, 1-(7-ammonioheptyl)guanidinium sulfate; GC7) an enzyme involved in the hypusination translation pathway, and the inhibitor plus H. pylori.
2020-05-26 | PXD010082 | Pride
Project description:Helicobacter pylori is designated as a class I carcinogen of human gastric cancer following long-term infection. During this process, H. pylori bacteria persist in proliferation and death, and release bacterial components that come into contact with gastric epithelial cells and regulate host cell function. However, the impact of long-term exposure to H. pylori lysate on the pathological changes of gastric cells is not clear. In this study, we aimed to investigate the regulation and mechanisms involved in gastric cell dysfunction following continuous exposure to H. pylori lysate. We co-cultured gastric cell lines GES-1 and MKN-45 with H. pylori lysate for 30 generations, and we found that sustained exposure to H. pylori lysate inhibited GES-1 cell invasion, migration, autophagy, and apoptosis, while it did not inhibit MKN-45 cell invasion or migration. Furthermore, Mongolian gerbils infected with H. pylori ATCC 43504 strains for 90 weeks confirmed the in vitro results. The clinical and in vitro data indicated that sustained exposure to H. pylori lysate inhibited cell apoptosis and autophagy through the Nod1-NF-κB/MAPK-ERK/FOXO4 signaling pathway. In conclusion, sustained exposure to H. pylori lysate promoted proliferation of gastric epithelial cells and inhibited autophagy and apoptosis via Nod1-NF-κB/MAPK-ERK/FOXO4 signaling pathway. In the process of H. pylori-induced gastric lesions, H. pylori lysate plays as an "accomplice" to carcinogenesis.
| S-EPMC7658535 | biostudies-literature
Project description:The genome of Helicobacter pylori is remarkable for its large number of restriction-modification (R-M) systems, and strain-specific diversity in R-M systems has been suggested to limit natural transformation, the major driving force of genetic diversification in H. pylori. We have determined the comprehensive methylomes of two H. pylori strains at single base resolution, using Single Molecule Real-Time (SMRT®) sequencing. For strains 26695 and J99-R3, 17 and 22 methylated sequence motifs were identified, respectively. For most motifs, almost all sites occurring in the genome were detected as methylated. Twelve novel methylation patterns corresponding to nine recognition sequences were detected (26695, 3; J99-R3, 6). Functional inactivation, correction of frameshifts as well as cloning and expression of candidate methyltransferases (MTases) permitted not only the functional characterization of multiple, yet undescribed, MTases, but also revealed novel features of both Type I and Type II R-M systems, including frameshift-mediated changes of sequence specificity and the interaction of one MTase with two alternative specificity subunits resulting in different methylation patterns. The methylomes of these well-characterized H. pylori strains will provide a valuable resource for future studies investigating the role of H. pylori R-M systems in limiting transformation as well as in gene regulation and host interaction.
| S-EPMC3936762 | biostudies-literature
Project description:BackgroundHelicobacter pylori is a human stomach pathogen, naturally-competent for DNA uptake, and prone to homologous recombination. Extensive homoplasy (i.e., phylogenetically-unlinked identical variations) observed in H. pylori genes is considered a hallmark of such recombination. However, H. pylori also exhibits a high mutation rate. The relative adaptive role of homologous recombination and mutation in species diversity is a highly-debated issue in biology. Recombination results in homoplasy. While convergent mutation can also account for homoplasy, its contribution is thought to be minor. We demonstrate here that, contrary to dogma, convergent mutation is a key contributor to Helicobacter pylori homoplasy, potentially driven by adaptive evolution of proteins.ResultsOur present genome-wide analysis shows that homoplastic nonsynonymous (amino acid replacement) changes are not typically accompanied by homoplastic synonymous (silent) variations. Moreover, the majority of the codon positions with homoplastic nonsynonymous changes also contain different (i.e. non-homoplastic) nonsynonymous changes arising from mutation only. This indicates that, to a considerable extent, nonsynonymous homoplasy is due to convergent mutations. High mutation rate or limited availability of evolvable sites cannot explain this excessive convergence, as suggested by our simulation studies. Rather, the genes with convergent mutations are overrepresented in distinct functional categories, suggesting possible selective responses to conditions such as distinct micro-niches in single hosts, and to differences in host genotype, physiology, habitat and diet.ConclusionsWe propose that mutational convergence is a key player in H. pylori's adaptation and extraordinary persistence in human hosts. High frequency of mutational convergence could be due to saturation of evolvable sites capable of responding to selection pressures, while the number of mutable residues is far from saturation. We anticipate a similar scenario of mutational vs. recombinational genome dynamics or plasticity for other naturally competent microbes where strong positive selection could favor frequent convergent mutations in adaptive protein evolution.
| S-EPMC6249973 | biostudies-literature
Project description:Helicobacter pylori (H. pylori), discovered in 1982, is a microaerophilic, spiral-shaped gram-negative bacterium that is able to colonize the human stomach. Nearly half of the world's population is infected by this pathogen. Its ability to induce gastritis, peptic ulcers, gastric cancer and mucosa-associated lymphoid tissue lymphoma has been confirmed. The susceptibility of an individual to these clinical outcomes is multifactorial and depends on H. pylori virulence, environmental factors, the genetic susceptibility of the host and the reactivity of the host immune system. Despite the host immune response, H. pylori infection can be difficult to eradicate. H. pylori is categorized as a group I carcinogen since this bacterium is responsible for the highest rate of cancer-related deaths worldwide. Early detection of cancer can be lifesaving. The 5-year survival rate for gastric cancer patients diagnosed in the early stages is nearly 90%. Gastric cancer is asymptomatic in the early stages but always progresses over time and begins to cause symptoms when untreated. In 97% of stomach cancer cases, cancer cells metastasize to other organs. H. pylori infection is responsible for nearly 60% of the intestinal-type gastric cancer cases but also influences the development of diffuse gastric cancer. The host genetic susceptibility depends on polymorphisms of genes involved in H. pylori-related inflammation and the cytokine response of gastric epithelial and immune cells. H. pylori strains differ in their ability to induce a deleterious inflammatory response. H. pylori-driven cytokines accelerate the inflammatory response and promote malignancy. Chronic H. pylori infection induces genetic instability in gastric epithelial cells and affects the DNA damage repair systems. Therefore, H. pylori infection should always be considered a pro-cancerous factor.
| S-EPMC5340805 | biostudies-literature