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Resolution of Gastric Cancer-Promoting Inflammation: A Novel Strategy for Anti-cancer Therapy.
Piazuelo MB, Riechelmann RP, Wilson KT, Algood HMS
(2019) Curr Top Microbiol Immunol 421: 319-359
MeSH Terms: Cytokines, Gastric Mucosa, Helicobacter Infections, Helicobacter pylori, Humans, Inflammation, Stomach Neoplasms, Tumor Microenvironment
Show Abstract · Added June 6, 2019
The connection between inflammation and cancer was initially recognized by Rudolf Virchow in the nineteenth century. During the last decades, a large body of evidence has provided support to his hypothesis, and now inflammation is recognized as one of the hallmarks of cancer, both in etiopathogenesis and ongoing tumor growth. Infection with the pathogen Helicobacter pylori is the primary causal factor in 90% of gastric cancer (GC) cases. As we increase our understanding of how chronic inflammation develops in the stomach and contributes to carcinogenesis, there is increasing interest in targeting cancer-promoting inflammation as a strategy to treat GC. Moreover, once cancer develops and anti-cancer immune responses are suppressed, there is evidence of a substantial shift in the microenvironment and new targets for immune therapy emerge. In this chapter, we provide insight into inflammation-related factors, including T lymphocytes, macrophages, pro-inflammatory chemokines, and cytokines, which promote H. pylori-associated GC initiation and growth. While intervening with chronic inflammation is not a new practice in rheumatology or gastroenterology, this approach has not been fully explored for its potential to prevent carcinogenesis or to contribute to the treatment of GC. This review highlights current and possible strategies for therapeutic intervention including (i) targeting pro-inflammatory mediators, (ii) targeting growth factors and pathways involved in angiogenesis in the gastric tumor microenvironment, and (iii) enhancing anti-tumor immunity. In addition, we highlight a significant number of clinical trials and discuss the importance of individual tumor characterization toward offering personalized immune-related therapy.
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8 MeSH Terms
VacA Targets Myeloid Cells in the Gastric Lamina Propria To Promote Peripherally Induced Regulatory T-Cell Differentiation and Persistent Infection.
Altobelli A, Bauer M, Velez K, Cover TL, Müller A
(2019) MBio 10:
MeSH Terms: Animals, Bacterial Proteins, Cell Differentiation, Dendritic Cells, Disease Models, Animal, Gastric Mucosa, Helicobacter Infections, Helicobacter pylori, Immune Evasion, Interleukin-10, Interleukin-23, Lung, Macrophages, Mice, Mucous Membrane, Myeloid Cells, T-Lymphocytes, Regulatory, Transforming Growth Factor beta
Show Abstract · Added April 11, 2019
The gastric bacterium causes a persistent infection that is directly responsible for gastric ulcers and gastric cancer in some patients and protective against allergic and other immunological disorders in others. The two outcomes of the -host interaction can be modeled in mice that are infected as immunocompetent adults and as neonates, respectively. Here, we have investigated the contribution of the immunomodulator VacA to -specific local and systemic immune responses in both models. We found that neonatally infected mice are colonized at higher levels than mice infected as adults and fail to generate effector T-cell responses to the bacteria; rather, T-cell responses in neonatally infected mice are skewed toward Foxp3-positive (Foxp3) regulatory T cells that are neuropilin negative and express RORγt. We found these peripherally induced regulatory T cells (pTregs) to be enriched, in a VacA-dependent manner, not only in the gastric mucosa but also in the lungs of infected mice. Pulmonary pTreg accumulation was observed in mice that have been infected neonatally with wild-type but not in mice that have been infected as adults or mice infected with a VacA null mutant. Finally, we traced VacA to gastric lamina propria myeloid cells and show that it suppressed interleukin-23 (IL-23) expression by dendritic cells and induced IL-10 and TGF-β expression in macrophages. Taken together, the results are consistent with the idea that creates a tolerogenic environment through its immunomodulator VacA, which skews T-cell responses toward Tregs, favors persistence, and affects immunity at distant sites. has coexisted with humans for at least 60.000 years and has evolved persistence strategies that allow it to evade host immunity and colonize its host for life. The VacA protein is expressed by all strains and is required for high-level persistent infection in experimental mouse models. Here, we show that VacA targets myeloid cells in the gastric mucosa to create a tolerogenic environment that facilitates regulatory T-cell differentiation, while suppressing effector T-cell priming and functionality. Tregs that are induced in the periphery during infection can be found not only in the stomach but also in the lungs of infected mice, where they are likely to affect immune responses to allergens.
Copyright © 2019 Altobelli et al.
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18 MeSH Terms
Intracellular Degradation of Helicobacter pylori VacA Toxin as a Determinant of Gastric Epithelial Cell Viability.
Foegeding NJ, Raghunathan K, Campbell AM, Kim SW, Lau KS, Kenworthy AK, Cover TL, Ohi MD
(2019) Infect Immun 87:
MeSH Terms: Autophagy, Bacterial Proteins, Cell Line, Cell Survival, Epithelial Cells, Gastric Mucosa, Helicobacter Infections, Helicobacter pylori, Humans, Hydrogen-Ion Concentration, Muramidase, Protein Stability, Protein Transport, Proteolysis
Show Abstract · Added February 7, 2019
VacA is a secreted pore-forming toxin that induces cell vacuolation and contributes to the pathogenesis of gastric cancer and peptic ulcer disease. We observed that purified VacA has relatively little effect on the viability of AGS gastric epithelial cells, but the presence of exogenous weak bases such as ammonium chloride (NHCl) enhances the susceptibility of these cells to VacA-induced vacuolation and cell death. Therefore, we tested the hypothesis that NHCl augments VacA toxicity by altering the intracellular trafficking of VacA or inhibiting intracellular VacA degradation. We observed VacA colocalization with LAMP1- and LC3-positive vesicles in both the presence and absence of NHCl, indicating that NHCl does not alter VacA trafficking to lysosomes or autophagosomes. Conversely, we found that supplemental NHCl significantly increases the intracellular stability of VacA. By conducting experiments using chemical inhibitors, stable ATG5 knockdown cell lines, and ATG16L1 knockout cells (generated using CRISPR/Cas9), we show that VacA degradation is independent of autophagy and proteasome activity but dependent on lysosomal acidification. We conclude that weak bases like ammonia, potentially generated during infection by urease and other enzymes, enhance VacA toxicity by inhibiting toxin degradation.
Copyright © 2019 American Society for Microbiology.
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14 MeSH Terms
Role of a Stem-Loop Structure in Transcript Stability.
Loh JT, Lin AS, Beckett AC, McClain MS, Cover TL
(2019) Infect Immun 87:
MeSH Terms: Antigens, Bacterial, Bacterial Proteins, DNA, Bacterial, Helicobacter Infections, Helicobacter pylori, Humans, Mutagenesis, Site-Directed, RNA Stability, RNA, Messenger
Show Abstract · Added February 7, 2019
CagA is a secreted effector protein that contributes to gastric carcinogenesis. Previous studies showed that there is variation among strains in the steady-state levels of CagA and that a strain-specific motif downstream of the transcriptional start site (the +59 motif) is associated with both high levels of CagA and premalignant gastric histology. The 5' untranslated region contains a predicted stem-loop-forming structure adjacent to the +59 motif. In the current study, we investigated the effect of the +59 motif and the adjacent stem-loop on transcript levels and mRNA stability. Using site-directed mutagenesis, we found that mutations predicted to disrupt the stem-loop structure resulted in decreased steady-state levels of both the transcript and the CagA protein. Additionally, these mutations resulted in a decreased mRNA half-life. Mutagenesis of the +59 motif without altering the stem-loop structure resulted in reduced steady-state transcript and CagA protein levels but did not affect transcript stability. transcript stability was not affected by increased sodium chloride concentrations, an environmental factor known to augment transcript levels and CagA protein levels. These results indicate that both a predicted stem-loop structure and a strain-specific +59 motif in the 5' untranslated region influence the levels of expression.
Copyright © 2019 American Society for Microbiology.
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9 MeSH Terms
MEK Inhibitor Reverses Metaplasia and Allows Re-Emergence of Normal Lineages in Helicobacter pylori-Infected Gerbils.
Yang Q, Yasuda T, Choi E, Toyoda T, Roland JT, Uchida E, Yoshida H, Seto Y, Goldenring JR, Nomura S
(2019) Gastroenterology 156: 577-581.e4
MeSH Terms: Acrylonitrile, Aniline Compounds, Animals, Benzimidazoles, Biopsy, Needle, Disease Models, Animal, Gastric Mucosa, Gerbillinae, Helicobacter Infections, Helicobacter pylori, Immunohistochemistry, Male, Metaplasia, Random Allocation, Reference Values, Treatment Outcome
Added November 14, 2018
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16 MeSH Terms
Serologic Response to Helicobacter pylori Proteins Associated With Risk of Colorectal Cancer Among Diverse Populations in the United States.
Butt J, Varga MG, Blot WJ, Teras L, Visvanathan K, Le Marchand L, Haiman C, Chen Y, Bao Y, Sesso HD, Wassertheil-Smoller S, Ho GYF, Tinker LE, Peek RM, Potter JD, Cover TL, Hendrix LH, Huang LC, Hyslop T, Um C, Grodstein F, Song M, Zeleniuch-Jacquotte A, Berndt S, Hildesheim A, Waterboer T, Pawlita M, Epplein M
(2019) Gastroenterology 156: 175-186.e2
MeSH Terms: Adolescent, Adult, Aged, Aged, 80 and over, Antibodies, Bacterial, Bacterial Proteins, Biomarkers, Case-Control Studies, Colorectal Neoplasms, Female, Helicobacter Infections, Helicobacter pylori, Host-Pathogen Interactions, Humans, Incidence, Male, Middle Aged, Prospective Studies, Risk Factors, Seroepidemiologic Studies, United States, Virulence, Young Adult
Show Abstract · Added February 7, 2019
BACKGROUND & AIMS - Previous studies reported an association of the bacteria Helicobacter pylori, the primary cause of gastric cancer, and risk of colorectal cancer (CRC). However, these findings have been inconsistent, appear to vary with population characteristics, and may be specific for virulence factor VacA. To more thoroughly evaluate the potential association of H pylori antibodies with CRC risk, we assembled a large consortium of cohorts representing diverse populations in the United States.
METHODS - We used H pylori multiplex serologic assays to analyze serum samples from 4063 incident cases of CRC, collected before diagnosis, and 4063 matched individuals without CRC (controls) from 10 prospective cohorts for antibody responses to 13 H pylori proteins, including virulence factors VacA and CagA. The association of seropositivity to H pylori proteins, as well as protein-specific antibody level, with odds of CRC was determined by conditional logistic regression.
RESULTS - Overall, 40% of controls and 41% of cases were H pylori-seropositive (odds ratio [OR], 1.09; 95% CI, 0.99-1.20). H pylori VacA-specific seropositivity was associated with an 11% increased odds of CRC (OR, 1.11; 95% CI, 1.01-1.22), and this association was particularly strong among African Americans (OR, 1.45; 95% CI, 1.08-1.95). Additionally, odds of CRC increased with level of VacA antibody in the overall cohort (P = .008) and specifically among African Americans (P = .007).
CONCLUSIONS - In an analysis of a large consortium of cohorts representing diverse populations, we found serologic responses to H pylori VacA to associate with increased risk of CRC risk, particularly for African Americans. Future studies should seek to understand whether this marker is related to virulent H pylori strains carried in these populations.
Copyright © 2019 AGA Institute. Published by Elsevier Inc. All rights reserved.
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MeSH Terms
Helicobacter: Inflammation, immunology, and vaccines.
Blosse A, Lehours P, Wilson KT, Gobert AP
(2018) Helicobacter 23 Suppl 1: e12517
MeSH Terms: Animals, Bacterial Vaccines, Epithelial Cells, Helicobacter Infections, Helicobacter pylori, Humans, Inflammation, Myeloid Cells
Show Abstract · Added December 16, 2018
Helicobacter pylori infection induces a chronic gastric inflammation which can lead to gastric ulcers and cancer. The mucosal immune response to H. pylori is first initiated by the activation of gastric epithelial cells that respond to numerous bacterial factors, such as the cytotoxin-associated gene A or the lipopolysaccharide intermediate heptose-1,7-bisphosphate. The response of these cells is orchestrated by different receptors including the intracellular nucleotide-binding oligomerization domain-containing protein 1 or the extracellular epidermal growth factor receptor. This nonspecific response leads to recruitment and activation of various myeloid (macrophages and dendritic cells) and T cells (T helper-17 and mucosal-associated invariant T cells), which magnify and maintain inflammation. In this review, we summarize the major advances made in the past year regarding the induction, the regulation, and the role of the innate and adaptive immune responses to H. pylori infection. We also recapitulate efforts that have been made to develop efficient vaccine strategies.
© 2018 John Wiley & Sons Ltd.
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8 MeSH Terms
Helicobacter pylori pathogen regulates p14ARF tumor suppressor and autophagy in gastric epithelial cells.
Horvat A, Noto JM, Ramatchandirin B, Zaika E, Palrasu M, Wei J, Schneider BG, El-Rifai W, Peek RM, Zaika AI
(2018) Oncogene 37: 5054-5065
MeSH Terms: Antigens, Bacterial, Autophagy, Bacterial Proteins, Cell Line, Tumor, Down-Regulation, Epithelial Cells, Gastric Mucosa, HCT116 Cells, Helicobacter Infections, Helicobacter pylori, Humans, Signal Transduction, Stomach, Stomach Neoplasms, Tumor Suppressor Protein p14ARF, Tumor Suppressor Protein p53, Ubiquitin-Protein Ligases, Up-Regulation, Virulence Factors
Show Abstract · Added September 25, 2018
Infection with Helicobacter pylori is one of the strongest risk factors for development of gastric cancer. Although these bacteria infect approximately half of the world's population, only a small fraction of infected individuals develops gastric malignancies. Interactions between host and bacterial virulence factors are complex and interrelated, making it difficult to elucidate specific processes associated with H. pylori-induced tumorigenesis. In this study, we found that H. pylori inhibits p14ARF tumor suppressor by inducing its degradation. This effect was found to be strain-specific. Downregulation of p14ARF induced by H. pylori leads to inhibition of autophagy in a p53-independent manner in infected cells. We identified TRIP12 protein as E3 ubiquitin ligase that is upregulated by H. pylori, inducing ubiquitination and subsequent degradation of p14ARF protein. Using isogenic H. pylori mutants, we found that induction of TRIP12 is mediated by bacterial virulence factor CagA. Increased expression of TRIP12 protein was found in infected gastric epithelial cells in vitro and human gastric mucosa of H. pylori-infected individuals. In conclusion, our data demonstrate a new mechanism of ARF inhibition that may affect host-bacteria interactions and facilitate tumorigenic transformation in the stomach.
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19 MeSH Terms
High-Salt Conditions Alter Transcription of Helicobacter pylori Genes Encoding Outer Membrane Proteins.
Loh JT, Beckett AC, Scholz MB, Cover TL
(2018) Infect Immun 86:
MeSH Terms: Bacterial Outer Membrane Proteins, Gene Expression Regulation, Bacterial, Helicobacter Infections, Helicobacter pylori, Humans, Operon, Sodium Chloride, Transcription, Genetic, Up-Regulation
Show Abstract · Added July 29, 2018
infection and high dietary salt intake are risk factors for the development of gastric adenocarcinoma. One possible mechanism by which a high-salt diet could influence gastric cancer risk is by modulating gene expression. In this study, we utilized transcriptome sequencing (RNA-seq) methodology to compare the transcriptional profiles of grown in media containing different concentrations of sodium chloride. We identified 118 differentially expressed genes (65 upregulated and 53 downregulated in response to high-salt conditions), including multiple members of 14 operons. Twenty-nine of the differentially expressed genes encode proteins previously shown to undergo salt-responsive changes in abundance, based on proteomic analyses. Real-time reverse transcription (RT)-PCR analyses validated differential expression of multiple genes encoding outer membrane proteins, including adhesins (SabA and HopQ) and proteins involved in iron acquisition (FecA2 and FecA3). Transcript levels of , , and are increased under high-salt conditions, whereas transcript levels of and are decreased under high-salt conditions. Transcription of , , , and is derepressed in an mutant strain, but salt-responsive transcription of these genes is not mediated by the ArsRS two-component system, and the CrdRS and FlgRS two-component systems do not have any detectable effects on transcription of these genes. In summary, these data provide a comprehensive view of transcriptional alterations that occur in response to high-salt environmental conditions.
Copyright © 2018 American Society for Microbiology.
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9 MeSH Terms
Selective killing of with pH-responsive helix-coil conformation transitionable antimicrobial polypeptides.
Xiong M, Bao Y, Xu X, Wang H, Han Z, Wang Z, Liu Y, Huang S, Song Z, Chen J, Peek RM, Yin L, Chen LF, Cheng J
(2017) Proc Natl Acad Sci U S A 114: 12675-12680
MeSH Terms: Amines, Animals, Anti-Bacterial Agents, Antimicrobial Cationic Peptides, Disease Models, Animal, Female, Glutamic Acid, Helicobacter Infections, Helicobacter pylori, Hydrogen-Ion Concentration, Mice, Mice, Inbred C57BL, Mice, Inbred ICR, Organ Specificity, Protein Conformation, alpha-Helical, Static Electricity, Stomach
Show Abstract · Added March 14, 2018
Current clinical treatment of infection, the main etiological factor in the development of gastritis, gastric ulcers, and gastric carcinoma, requires a combination of at least two antibiotics and one proton pump inhibitor. However, such triple therapy suffers from progressively decreased therapeutic efficacy due to the drug resistance and undesired killing of the commensal bacteria due to poor selectivity. Here, we report the development of antimicrobial polypeptide-based monotherapy, which can specifically kill under acidic pH in the stomach while inducing minimal toxicity to commensal bacteria under physiological pH. Specifically, we designed a class of pH-sensitive, helix-coil conformation transitionable antimicrobial polypeptides (HCT-AMPs) (PGA)--(PHLG-MHH), bearing randomly distributed negatively charged glutamic acid and positively charged poly(γ-6--(methyldihexylammonium)hexyl-l-glutamate) (PHLG-MHH) residues. The HCT-AMPs showed unappreciable toxicity at physiological pH when they adopted random coiled conformation. Under acidic condition in the stomach, they transformed to the helical structure and exhibited potent antibacterial activity against , including clinically isolated drug-resistant strains. After oral gavage, the HCT-AMPs afforded comparable killing efficacy to the triple-therapy approach while inducing minimal toxicity against normal tissues and commensal bacteria, in comparison with the remarkable killing of commensal bacteria by 65% and 86% in the ileal contents and feces, respectively, following triple therapy. This strategy renders an effective approach to specifically target and kill in the stomach while not harming the commensal bacteria/normal tissues.
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17 MeSH Terms