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Jarzab M, Skorko-Glonek J. There Are No Insurmountable Barriers: Passage of the Helicobacter pylori VacA Toxin from Bacterial Cytoplasm to Eukaryotic Cell Organelle. MEMBRANES 2023; 14:11. [PMID: 38248700 PMCID: PMC10821523 DOI: 10.3390/membranes14010011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 12/20/2023] [Accepted: 12/23/2023] [Indexed: 01/23/2024]
Abstract
The Gram-negative bacterium Helicobacter pylori is a very successful pathogen, one of the most commonly identified causes of bacterial infections in humans worldwide. H. pylori produces several virulence factors that contribute to its persistence in the hostile host habitat and to its pathogenicity. The most extensively studied are cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA). VacA is present in almost all H. pylori strains. As a secreted multifunctional toxin, it assists bacterial colonization, survival, and proliferation during long-lasting infections. To exert its effect on gastric epithelium and other cell types, VacA undergoes several modifications and crosses multiple membrane barriers. Once inside the gastric epithelial cell, VacA disrupts many cellular-signaling pathways and processes, leading mainly to changes in the efflux of various ions, the depolarization of membrane potential, and perturbations in endocytic trafficking and mitochondrial function. The most notable effect of VacA is the formation of vacuole-like structures, which may lead to apoptosis. This review focuses on the processes involved in VacA secretion, processing, and entry into host cells, with a particular emphasis on the interaction of the mature toxin with host membranes and the formation of transmembrane pores.
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Affiliation(s)
| | - Joanna Skorko-Glonek
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland;
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Zhang J, Ning J, Fu W, Shi Y, Zhang J, Ding S. CMTM3 protects the gastric epithelial cells from apoptosis and promotes IL-8 by stabilizing NEMO during Helicobacter pylori infection. Gut Pathog 2023; 15:6. [PMID: 36782312 PMCID: PMC9924195 DOI: 10.1186/s13099-023-00533-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 02/06/2023] [Indexed: 02/15/2023] Open
Abstract
BACKGROUND CKLF-like MARVEL transmembrane domain containing 3 (CMTM3) plays an important role in cancer development. Although Helicobacter pylori (H. pylori) infection is a main cause of gastric cancer, the function of CMTM3 during H. pylori infection remains unclear. CMTM3 expression levels in tissues from H. pylori-infected patients and cells co-cultured with H. pylori were analyzed. qRT-PCR and ELISA were used to investigate the effects of CMTM3 on interleukin 8 (IL-8) expression. Annexin V/propidium iodide staining was performed to evaluate the function of CMTM3 in the apoptosis of gastric epithelial cells. Proteomic analysis was performed to explore the underlying mechanism of CMTM3 during H. pylori infection. The interaction between CMTM3 and NEMO was determined via co-immunoprecipitation, HA-ubiquitin pull-down assay, and immunofluorescence. RESULTS H. pylori induced a significant increase in CMTM3 expression. CMTM3 inhibited gastric mucosal epithelial cells from apoptosis and increased the expression level of IL-8 during H. pylori infection. KEGG pathway enrichment analysis revealed that differentially expressed proteins were involved in epithelial cell signaling in H. pylori infection. CMTM3 directly interacted with NEMO, which promoted protein stabilization by down-regulation of its ubiquitylation. CONCLUSIONS CMTM3 reduces apoptosis and promotes IL-8 expression in the gastric epithelial cells by stabilizing NEMO during H. pylori infection. These findings characterize a new role for CMTM3 in host-pathogen interactions and provide novel insight into the molecular regulation of NEMO.
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Affiliation(s)
- Jing Zhang
- grid.411642.40000 0004 0605 3760Department of Gastroenterology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191 People’s Republic of China
| | - Jing Ning
- grid.411642.40000 0004 0605 3760Department of Gastroenterology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191 People’s Republic of China
| | - Weiwei Fu
- grid.411642.40000 0004 0605 3760Department of Gastroenterology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191 People’s Republic of China
| | - Yanyan Shi
- grid.411642.40000 0004 0605 3760Research Center of Clinical Epidemiology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191 People’s Republic of China
| | - Jing Zhang
- grid.411642.40000 0004 0605 3760Department of Gastroenterology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191 People’s Republic of China
| | - Shigang Ding
- Department of Gastroenterology, Peking University Third Hospital, 49 Huayuan North Road, Haidian District, Beijing, 100191, People's Republic of China.
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Keikha M, Ali-Hassanzadeh M, Karbalaei M. Association of Helicobacter pylori vacA genotypes and peptic ulcer in Iranian population: a systematic review and meta-analysis. BMC Gastroenterol 2020; 20:266. [PMID: 32795257 PMCID: PMC7427722 DOI: 10.1186/s12876-020-01406-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 07/29/2020] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Helicobacter pylori is accounted as the most etiologic agent for digestive disorders, in particular, the most important of them i.e. peptic ulcer and gastric cancer. In the recent years, association of vacA genotypes and gastrointestinal disorders has attracted a lot of attention. In present study, we assessed the correlation between vacA genotypes (s1, s2, m1, m2, s1m1, s1m2, s2m1 and s2m2) and development to peptic ulcer in Iranian population. METHODS In our study, first, 24 original articles containing of information of 3328 patients were evaluated. Statistical analysis was done by Comprehensive Meta-Analysis version 2.0 software (Biostat, Englewood, NJ, USA). In this regards, we used from fixed-effects model for analysis of data with low heterogeneity, while for analysis of data with high heterogeneity (I2 statistic index > 25%, Cochrane Q statistic p value < 0.05), random-effects model was used. RESULTS Abundance of each of s1, s2, m1, m2, s1m1, s1m2, s2m1, and s2m2 was estimated 36.24, 28.32, 42.90 29.86, 27.88, 32.34, 15.70, and 25.94%, respectively. According to the results, the m1, s1, and s1m2 genotypes were among the most prevalent genotypes among the Iranian patients, whereas, s2m1 genotype had the lowest frequency. CONCLUSIONS Overall, 24 articles (total participants = 3328) were included in this comprehensive analysis. H. pylori infection rate were 90.26% in these cases, so that 33.65% of whom had peptic ulcer. Moreover, the abundance of each vacA genotypes including s1, s2, m1, m2, s1m1, s1m2, s2m1, and s2m2 was estimated as 36.24, 28.32, 42.90 29.86, 27.88, 32.34, 15.70, and 25.94% respectively. We demonstrated that there is a significant relationship between infection of stomach with m1, s1m1, and s2m1 genotypes and development to peptic ulcer disease.
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Affiliation(s)
- Masoud Keikha
- Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
- Department of Microbiology and Virology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
- Student Research Committee, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mohammad Ali-Hassanzadeh
- Department of Immunology, School of Medicine, Jiroft University of Medical Sciences, Jiroft, Iran
| | - Mohsen Karbalaei
- Department of Microbiology and Virology, School of Medicine, Jiroft University of Medical Sciences, Jiroft, Iran.
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Papaefthymiou A, Doulberis M, Katsinelos P, Liatsos C, Polyzos SA, Kotronis G, Papanikolaou K, Kountouras J. Impact of nitric oxide's bidirectional role on glaucoma: focus onHelicobacter pylori–related nitrosative stress. Ann N Y Acad Sci 2020; 1465:10-28. [DOI: 10.1111/nyas.14253] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 09/07/2019] [Accepted: 09/17/2019] [Indexed: 12/12/2022]
Affiliation(s)
| | - Michael Doulberis
- Department of Gastroenterology and HepatologyUniversity of Zurich Zurich Switzerland
- Department of Internal Medicine, Second Medical Clinic, Ippokration HospitalAristotle University of Thessaloniki Thessaloniki Macedonia Greece
| | - Panagiotis Katsinelos
- Department of Internal Medicine, Second Medical Clinic, Ippokration HospitalAristotle University of Thessaloniki Thessaloniki Macedonia Greece
| | - Christos Liatsos
- Department of Gastroenterology401 General Military Hospital of Athens Athens Greece
| | - Stergios A. Polyzos
- Department of Internal Medicine, Second Medical Clinic, Ippokration HospitalAristotle University of Thessaloniki Thessaloniki Macedonia Greece
- First Department of Pharmacology, School of MedicineAristotle University of Thessaloniki Thessaloniki Macedonia Greece
| | - Georgios Kotronis
- Department of Internal MedicineAgios Pavlos General Hospital Thessaloniki Macedonia Greece
| | - Katerina Papanikolaou
- Department of Internal Medicine, Second Medical Clinic, Ippokration HospitalAristotle University of Thessaloniki Thessaloniki Macedonia Greece
| | - Jannis Kountouras
- Department of Internal Medicine, Second Medical Clinic, Ippokration HospitalAristotle University of Thessaloniki Thessaloniki Macedonia Greece
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Lee MH, Yang JY, Cho Y, Woo HJ, Kwon HJ, Kim DH, Park M, Moon C, Yeon MJ, Kim HW, Seo WD, Kim SH, Kim JB. Inhibitory Effects of Menadione on Helicobacter pylori Growth and Helicobacter pylori-Induced Inflammation via NF-κB Inhibition. Int J Mol Sci 2019; 20:ijms20051169. [PMID: 30866458 PMCID: PMC6429389 DOI: 10.3390/ijms20051169] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/01/2019] [Accepted: 03/04/2019] [Indexed: 12/19/2022] Open
Abstract
H. pylori is classified as a group I carcinogen by WHO because of its involvement in gastric cancer development. Several reports have suggested anti-bacterial effects of menadione, although the effect of menadione on major virulence factors of H. pylori and H. pylori-induced inflammation is yet to be elucidated. In this study, therefore, we demonstrated that menadione has anti-H. pylori and anti-inflammatory effects. Menadione inhibited growth of H. pylori reference strains and clinical isolates. Menadione reduced expression of vacA in H. pylori, and translocation of VacA protein into AGS (gastric adenocarcinoma cell) was also decreased by menadione treatment. This result was concordant with decreased apoptosis in AGS cells infected with H. pylori. Moreover, cytotoxin-associated protein A (CagA) translocation into H. pylori-infected AGS cells was also decreased by menadione. Menadione inhibited expression of several type IV secretion system (T4SS) components, including virB2, virB7, virB8, and virB10, that are responsible for translocation of CagA into host cells. In particular, menadione inhibited nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) activation and thereby reduced expression of the proinflammatory cytokines such as IL-1β, IL-6, IL-8, and TNF-α in AGS as well as in THP-1 (monocytic leukemia cell) cell lines. Collectively, these results suggest the anti-bacterial and anti-inflammatory effects of menadione against H. pylori.
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Affiliation(s)
- Min Ho Lee
- Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, Wonju 26493, Korea.
- Forensic DNA Division, National Forensic Service, Wonju 26460, Korea.
| | - Ji Yeong Yang
- Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, Wonju 26493, Korea.
| | - Yoonjung Cho
- Forensic DNA Division, National Forensic Service, Wonju 26460, Korea.
| | - Hyun Jun Woo
- Department of Clinical Laboratory Science, College of Medical Sciences, Daegu Haany University, Gyeongsan 38610, Korea.
| | - Hye Jin Kwon
- Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, Wonju 26493, Korea.
| | - Do Hyun Kim
- Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, Wonju 26493, Korea.
| | - Min Park
- Department of Biomedical Laboratory Science, Daekyeung University, Gyeongsan 38547, Korea.
| | - Cheol Moon
- Department of Clinical Laboratory Science, Semyung University, Jecheon 27136, Korea.
| | - Min Ji Yeon
- Natural Products Research Center, Korea Institute of Science and Technology (KIST) Gangneung 25451, Korea.
| | - Hyun Woo Kim
- Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, Wonju 26493, Korea.
| | - Woo-Duck Seo
- National Institute of Crop Science (NICS), Rural Development Administration (RDA), Wanju-Gun 55365, Korea.
| | - Sa-Hyun Kim
- Department of Clinical Laboratory Science, Semyung University, Jecheon 27136, Korea.
| | - Jong-Bae Kim
- Department of Biomedical Laboratory Science, College of Health Sciences, Yonsei University, Wonju 26493, Korea.
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Chauhan N, Tay ACY, Marshall BJ, Jain U. Helicobacter pylori VacA, a distinct toxin exerts diverse functionalities in numerous cells: An overview. Helicobacter 2019; 24:e12544. [PMID: 30324717 DOI: 10.1111/hel.12544] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/21/2018] [Accepted: 09/06/2018] [Indexed: 02/06/2023]
Abstract
BACKGROUND Helicobacter pylori, gastric cancer-causing bacteria, survive in their gastric environment of more than 50% of the world population. The presence of H. pylori in the gastric vicinity promotes the development of various diseases including peptic ulcer and gastric carcinoma. H. pylori produce and secret Vacuolating cytotoxin A (VacA), a major toxin facilitating the bacteria against the host defense system. The toxin causes multiple effects in epithelial cells and immune cells, especially T cells, B cells, and Macrophages. METHODS This review describes the diverse functionalities of protein toxin VacA. The specific objective of this review is to address the overall structure, mechanism, and functions of VacA in various cell types. The recent advancements are summarized and discussed and thus conclusion is drawn based on the overall reported evidences. RESULTS The searched articles on H. pylori VacA were evaluated and limited up to 66 articles for this review. The articles were divided into four major categories including articles on vacA gene, VacA toxin, distinct effects of VacA toxin, and their effects on various cells. Based on these studies, the review article was prepared. CONCLUSIONS This review describes an overview of how VacA is secreted by H. pylori and contributes to colonization and virulence in multiple ways by affecting epithelial cells, T cells, Dendritic cells, B cells, and Macrophages. The reported evidence suggests that the comprehensive outlook need to be developed for understanding distinctive functionalities of VacA.
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Affiliation(s)
- Nidhi Chauhan
- Amity Institute of Nanotechnology, Amity University, Noida, Uttar Pradesh, India
| | - Alfred Chin Yen Tay
- The Marshall Centre for Infectious Diseases Research and Training, The University of Western Australia, Nedlands, Western Australia, Australia.,Shenzhen Dapeng New District Kuichong People Hospital, Shenzhen, Guangdong, China
| | - Barry J Marshall
- The Marshall Centre for Infectious Diseases Research and Training, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Utkarsh Jain
- Amity Institute of Nanotechnology, Amity University, Noida, Uttar Pradesh, India
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Portugal L, Muñóz-Garay C, Martínez de Castro DL, Soberón M, Bravo A. Toxicity of Cry1A toxins from Bacillus thuringiensis to CF1 cells does not involve activation of adenylate cyclase/PKA signaling pathway. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2017; 80:21-31. [PMID: 27867074 DOI: 10.1016/j.ibmb.2016.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 11/12/2016] [Accepted: 11/16/2016] [Indexed: 06/06/2023]
Abstract
Bacillus thuringiensis (Bt) bacteria produce Cry toxins that are able to kill insect pests. Different models explaining the mode of action of these toxins have been proposed. The pore formation model proposes that the toxin creates pores in the membrane of the larval midgut cells after interaction with different receptors such as cadherin, aminopeptidase N and alkaline phosphatase and that this pore formation activity is responsible for the toxicity of these proteins. The alternative model proposes that interaction with cadherin receptor triggers an intracellular cascade response involving protein G, adenylate cyclase (AC) and protein kinase A (PKA). In addition, it was shown that Cry toxins induce a defense response in the larvae involving the activation of mitogen-activated kinases such as MAPK p38 in different insect orders. Here we analyzed the mechanism of action of Cry1Ab and Cry1Ac toxins and a collection of mutants from these toxins in the insect cell line CF1 from Choristoneura fumiferana, that is naturally sensitive to these toxins. Our results show that both toxins induced permeability of K+ ions into the cells. The initial response after intoxication with Cry1Ab and Cry1Ac toxins involves the activation of a defense response that involves the phosphorylation of MAPK p38. Analysis of activation of PKA and AC activities indicated that the signal transduction involving PKA, AC and cAMP was not activated during Cry1Ab or Cry1Ac intoxication. In contrast we show that Cry1Ab and Cry1Ac activate apoptosis. These data indicate that Cry toxins can induce an apoptotic death response not related with AC/PKA activation. Since Cry1Ab and Cry1Ac toxins affected K+ ion permeability into the cells, and that mutant toxins affected in pore formation are not toxic to CF1, we propose that pore formation activity of the toxins is responsible of triggering cell death response in CF1cells.
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Affiliation(s)
- Leivi Portugal
- Departamento de Microbiología, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250 Morelos, Mexico
| | - Carlos Muñóz-Garay
- Departamento de Microbiología, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250 Morelos, Mexico
| | - Diana L Martínez de Castro
- Departamento de Microbiología, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250 Morelos, Mexico
| | - Mario Soberón
- Departamento de Microbiología, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250 Morelos, Mexico
| | - Alejandra Bravo
- Departamento de Microbiología, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250 Morelos, Mexico.
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Abstract
Mitochondria are the "power house" of a cell continuously generating ATP to ensure its proper functioning. The constant production of ATP via oxidative phosphorylation demands a large electrochemical force that drives protons across the highly selective and low-permeable mitochondrial inner membrane. Besides the conventional role of generating ATP, mitochondria also play an active role in calcium signaling, generation of reactive oxygen species (ROS), stress responses, and regulation of cell-death pathways. Deficiencies in these functions result in several pathological disorders like aging, cancer, diabetes, neurodegenerative and cardiovascular diseases. A plethora of ion channels and transporters are present in the mitochondrial inner and outer membranes which work in concert to preserve the ionic equilibrium of a cell for the maintenance of cell integrity, in physiological as well as pathophysiological conditions. For, e.g., mitochondrial cation channels KATP and BKCa play a significant role in cardioprotection from ischemia-reperfusion injury. In addition to the cation channels, mitochondrial anion channels are equally essential, as they aid in maintaining electro-neutrality by regulating the cell volume and pH. This chapter focusses on the information on molecular identity, structure, function, and physiological relevance of mitochondrial chloride channels such as voltage dependent anion channels (VDACs), uncharacterized mitochondrial inner membrane anion channels (IMACs), chloride intracellular channels (CLIC) and the aspects of forthcoming chloride channels.
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Affiliation(s)
- Devasena Ponnalagu
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, Room 8154, Mail Stop 488, Philadelphia, PA, 19102-1192, USA
| | - Harpreet Singh
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, Room 8154, Mail Stop 488, Philadelphia, PA, 19102-1192, USA.
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Zaidi SF. Helicobacter pylori associated Asian enigma: Does diet deserve distinction? World J Gastrointest Oncol 2016; 8:341-350. [PMID: 27096029 PMCID: PMC4824712 DOI: 10.4251/wjgo.v8.i4.341] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 11/23/2015] [Accepted: 01/22/2016] [Indexed: 02/05/2023] Open
Abstract
Helicobacter pylori (H. pylori) is one of the most widespread infections in humans worldwide that chronically infects up to 50% of the world’s population. The infection is involved in the pathogenesis of chronic active gastritis, peptic ulcer, mucosa-associated lymphoid tissue lymphoma and gastric cancer, therefore, it has been classified as class I definite carcinogen by the World Health Organization. Despite the established etiological role of H. pylori, its actual distribution and association with related diseases is controversial and there is a large intercountry variation especially among Asian countries. H. pylori infection is more frequent in developing countries like India, Pakistan, and Bangladesh as compared to developed Asian countries like Japan, China and South Korea. However, the frequency of gastric cancer is comparatively lower in India, Pakistan, and Bangladesh with that of Japan, China and South Korea. Such phenomenon of clinical diversity, defined as enigma, is judged by genetic variability of the infecting H. pylori strains, differences in the host genetic background in various ethnic groups, and environmental factors such as dietary habits. Most of the studies have so far focused on the bacterial factor while environmental issues, including dietary components, were not given due attention as one of the factors related with H. pylori associated gastric carcinogenesis. The dietary factor has been suggested to play an important role in H. pylori related carcinogenesis, and in this respect several studies have corroborated the intake of various dietary components as modulatory factors for gastric cancer risk. In this review, such studies, from in vitro experiments to clinical trials, are being focused in detail with respect to enigma associated with H. pylori. It may be conceivably concluded from the available evidence that dietary factor can be a game changer in the scenario of Asian enigma, particularly in high risk population infected with virulent H. pylori strains, however further affirmation studies are desperately needed to achieve conclusive outcomes.
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Khalil AAK, Park WS, Kim HJ, Akter KM, Ahn MJ. Anti-Helicobacter pyloriCompounds fromPolygonum cuspidatum. ACTA ACUST UNITED AC 2016. [DOI: 10.20307/nps.2016.22.3.220] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Atif Ali Khan Khalil
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University, Jinju 52828, Korea
| | - Woo Sung Park
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University, Jinju 52828, Korea
| | - Hye Jin Kim
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University, Jinju 52828, Korea
| | - Kazi Marjahan Akter
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University, Jinju 52828, Korea
| | - Mi-Jeong Ahn
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University, Jinju 52828, Korea
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Cortactin Mediates Apoptosis of Gastric Epithelial Cells Induced by VacA Protein of Helicobacter pylori. Dig Dis Sci 2016; 61:80-90. [PMID: 26289258 DOI: 10.1007/s10620-015-3836-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 07/30/2015] [Indexed: 12/11/2022]
Abstract
BACKGROUND Vacuolating cytotoxin antigen (VacA) is one of the major virulence factors in Helicobacter pylori (H. pylori), which is responsible for cell vacuolar degeneration and apoptotic cell death. A candidate host factor which mediates this process is cortactin, a protein associated with the processes of colonization and adhesion of H. pylori in gastric epithelium. AIM To investigate the role of cortactin in VacA-induced apoptosis of gastric epithelial cells. METHODS Cortactin expression and shRNA lentiviral constructs were developed and transduced into the human gastric cancer cell line, AGS. VacA protein was purified from H. pylori cultures, acid-activated, and co-incubated with the transduced cell populations. Apoptosis was detected by flow cytometry, and the levels of the pro- and anti-apoptotic proteins Bax and Bcl-2 were determined by Western blot. RESULTS Acid-activated purified VacA induced apoptosis in the parental AGS cells. Increased expression of cortactin (AGS/cortactin) led to a greater percentage of cells undergoing apoptosis. In contrast, knockdown of cortactin with shRNA (AGS/cortactin-shRNA) decreased the percentage of apoptotic cells. The protein levels of pro- and anti-apoptotic proteins Bax and Bcl-2 were increased and decreased in AGS/cortactin cells relative to the parental AGS cells. In the AGS/cortactin-shRNA cells, Bax protein levels were decreased, while Bcl-2 protein was increased. CONCLUSIONS The results indicate that cortactin is involved in the regulation of apoptosis induced by VacA in gastric cells.
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Abstract
The connection between Helicobacter pylori (Hp) infection and eye diseases has been increasingly reported in the literature and in active research. The implication of this bacterium in chronic eye diseases, such as blepharitis, glaucoma, central serous chorioretinopathy and others, has been hypothesized. Although the mechanisms by which this association occurs are currently unknown, this review describes shared pathogenetic mechanisms in an attempt to identify a lowest common denominator between eye diseases and Hp infection. The aim of this review is to assess whether different studies could be compared and to establish whether or not Hp infection and Eye diseases share common pathogenetic aspects. In particular, it has been focused on oxidative damage as a possible link between these pathologies. Text word search in Medline from 1998 to July 2014. 152 studies were included in our review. Were taken into considerations only studies that related eye diseases more frequent and/or known. Likely oxidative stress plays a key role. All of the diseases studied seem to follow a common pattern that implicates a cellular response correlated with a sublethal dose of oxidative stress. These alterations seem to be shared by both Hp infections and ocular diseases and include the following: decline in mitochondrial function, increases in the rate of reactive oxygen species production, accumulation of mitochondrial DNA mutations, increases in the levels of oxidative damage to DNA, proteins and lipids, and decreases in the capacity to degrade oxidatively damaged proteins and other macromolecules. This cascade of events appears to repeat itself in different diseases, regardless of the identity of the affected tissue. The trabecular meshwork, conjunctiva, and retina can each show how oxidative stress may acts as a common disease effector as the Helicobacter infection spreads, supported by the increased oxidative damage and other inflammation.
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Affiliation(s)
- Sergio Claudio Saccà
- From the IRCCS Azienda Ospedaliera Universitaria San Martino - IST Department of Head/Neck Pathologies, St Martino Hospital, Ophthalmology Unit, 16132 Genoa, Italy (SCS); Department of Neurosciences, Ophthalmology and Genetics, University of Genoa, Eye Clinic, 16132 Genoa, Italy (AV); Department of Health Sciences, University of Genoa, 16132 Genoa, Italy (AP, AI); Mutagenesis Unit, IRCCS Azienda Ospedaliera Universitaria San Martino - IST, National Institute for Cancer Research, 16132 Genoa, Italy (AI)
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Vale FF, Oleastro M. Overview of the phytomedicine approaches against Helicobacter pylori. World J Gastroenterol 2014; 20:5594-5609. [PMID: 24914319 PMCID: PMC4024768 DOI: 10.3748/wjg.v20.i19.5594] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 12/18/2013] [Accepted: 03/06/2014] [Indexed: 02/06/2023] Open
Abstract
Helicobacter pylori (H. pylori) successfully colonizes the human stomach of the majority of the human population. This infection always causes chronic gastritis, but may evolve to serious outcomes, such as peptic ulcer, gastric carcinoma or mucosa-associated lymphoid tissue lymphoma. H. pylori first line therapy recommended by the Maastricht-4 Consensus Report comprises the use of two antibiotics and a proton-pomp inhibitor, but in some regions failure associated with this treatment is already undesirable high. Indeed, treatment failure is one of the major problems associated with H. pylori infection and is mainly associated with bacterial antibiotic resistance. In order to counteract this situation, some effort has been allocated during the last years in the investigation of therapeutic alternatives beyond antibiotics. These include vaccines, probiotics, photodynamic inactivation and phage therapy, which are briefly revisited in this review. A particular focus on phytomedicine, also described as herbal therapy and botanical therapy, which consists in the use of plant extracts for medicinal purposes, is specifically addressed, namely considering its history, category of performed studies, tested compounds, active principle and mode of action. The herbs already experienced are highly diverse and usually selected from products with a long history of employment against diseases associated with H. pylori infection from each country own folk medicine. The studies demonstrated that many phytomedicine products have an anti-H. pylori activity and gastroprotective action. Although the mechanism of action is far from being completely understood, current knowledge correlates the beneficial action of herbs with inhibition of essential H. pylori enzymes, modulation of the host immune system and with attenuation of inflammation.
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Akazawa Y, Isomoto H, Matsushima K, Kanda T, Minami H, Yamaghchi N, Taura N, Shiozawa K, Ohnita K, Takeshima F, Nakano M, Moss J, Hirayama T, Nakao K. Endoplasmic reticulum stress contributes to Helicobacter pylori VacA-induced apoptosis. PLoS One 2013; 8:e82322. [PMID: 24349255 PMCID: PMC3862672 DOI: 10.1371/journal.pone.0082322] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Accepted: 10/31/2013] [Indexed: 12/17/2022] Open
Abstract
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.
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Affiliation(s)
- Yuko Akazawa
- Department of Gastroenterology and Hepatology, Nagasaki University Hospital, Nagasaki, Japan
- * E-mail:
| | - Hajime Isomoto
- Department of Gastroenterology and Hepatology, Nagasaki University Hospital, Nagasaki, Japan
| | - Kayoko Matsushima
- Department of Gastroenterology and Hepatology, Nagasaki University Hospital, Nagasaki, Japan
| | - Tsutomu Kanda
- Department of Gastroenterology and Hepatology, Nagasaki University Hospital, Nagasaki, Japan
| | - Hitomi Minami
- Department of Gastroenterology and Hepatology, Nagasaki University Hospital, Nagasaki, Japan
| | - Naoyuki Yamaghchi
- Department of Gastroenterology and Hepatology, Nagasaki University Hospital, Nagasaki, Japan
| | - Naota Taura
- Department of Gastroenterology and Hepatology, Nagasaki University Hospital, Nagasaki, Japan
| | - Ken Shiozawa
- Department of Gastroenterology and Hepatology, Nagasaki University Hospital, Nagasaki, Japan
| | - Ken Ohnita
- Department of Gastroenterology and Hepatology, Nagasaki University Hospital, Nagasaki, Japan
| | - Fuminao Takeshima
- Department of Gastroenterology and Hepatology, Nagasaki University Hospital, Nagasaki, Japan
| | - Masayuki Nakano
- Department of Bacteriology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Joel Moss
- Cardiovascular and Pulmonary Branch, NHLBI, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Toshiya Hirayama
- Department of Bacteriology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Kazuhiko Nakao
- Department of Gastroenterology and Hepatology, Nagasaki University Hospital, Nagasaki, Japan
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Kim IJ, Blanke SR. Remodeling the host environment: modulation of the gastric epithelium by the Helicobacter pylori vacuolating toxin (VacA). Front Cell Infect Microbiol 2012; 2:37. [PMID: 22919629 PMCID: PMC3417592 DOI: 10.3389/fcimb.2012.00037] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Accepted: 03/05/2012] [Indexed: 12/13/2022] Open
Abstract
Virulence mechanisms underlying Helicobacter pylori persistence and disease remain poorly understood, in part, because the factors underlying disease risk are multifactorial and complex. Among the bacterial factors that contribute to the cumulative pathophysiology associated with H. pylori infections, the vacuolating cytotoxin (VacA) is one of the most important. Analogous to a number of H. pylori genes, the vacA gene exhibits allelic mosaicism, and human epidemiological studies have revealed that several families of toxin alleles are predictive of more severe disease. Animal model studies suggest that VacA may contribute to pathogenesis in several ways. VacA functions as an intracellular-acting protein exotoxin. However, VacA does not fit the current prototype of AB intracellular-acting bacterial toxins, which elaborate modulatory effects through the action of an enzymatic domain translocated inside host cells. Rather, VacA may represent an alternative prototype for AB intracellular acting toxins that modulate cellular homeostasis by forming ion-conducting intracellular membrane channels. Although VacA seems to form channels in several different membranes, one of the most important target sites is the mitochondrial inner membrane. VacA apparently take advantage of an unusual intracellular trafficking pathway to mitochondria, where the toxin is imported and depolarizes the inner membrane to disrupt mitochondrial dynamics and cellular energy homeostasis as a mechanism for engaging the apoptotic machinery within host cells. VacA remodeling of the gastric environment appears to be fine-tuned through the action of the Type IV effector protein CagA which, in part, limits the cytotoxic effects of VacA in cells colonized by H. pylori.
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Affiliation(s)
- Ik-Jung Kim
- Department of Microbiology, Institute for Genomic Biology, University of Illinois, Urbana IL, USA
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16
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Role of Abl and Src family kinases in actin-cytoskeletal rearrangements induced by the Helicobacter pylori CagA protein. Eur J Cell Biol 2011; 90:880-90. [DOI: 10.1016/j.ejcb.2010.11.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 11/12/2010] [Accepted: 11/15/2010] [Indexed: 12/17/2022] Open
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Rassow J. Helicobacter pylori vacuolating toxin A and apoptosis. Cell Commun Signal 2011; 9:26. [PMID: 22044628 PMCID: PMC3266207 DOI: 10.1186/1478-811x-9-26] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 11/01/2011] [Indexed: 12/16/2022] Open
Abstract
VacA, the vacuolating cytotoxin A of Helicobacter pylori, induces apoptosis in epithelial cells of the gastic mucosa and in leukocytes. VacA is released by the bacteria as a protein of 88 kDa. At the outer surface of host cells, it binds to the sphingomyelin of lipid rafts. At least partially, binding to the cells is facilitated by different receptor proteins. VacA is internalized by a clathrin-independent mechanism and initially accumulates in GPI-anchored proteins-enriched early endosomal compartments. Together with early endosomes, VacA is distributed inside the cells. Most of the VacA is eventually contained in the membranes of vacuoles. VacA assembles in hexameric oligomers forming an anion channel of low conductivity with a preference for chloride ions. In parallel, a significant fraction of VacA can be transferred from endosomes to mitochondria in a process involving direct endosome-mitochondria juxtaposition. Inside the mitochondria, VacA accumulates in the mitochondrial inner membrane, probably forming similar chloride channels as observed in the vacuoles. Import into mitochondria is mediated by the hydrophobic N-terminus of VacA. Apoptosis is triggered by loss of the mitochondrial membrane potential, recruitment of Bax and Bak, and release of cytochrome c.
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Affiliation(s)
- Joachim Rassow
- Ruhr-Universität Bochum, Institut für Physiologische Chemie, Medizinische Fakultät, Gebäude MA3, D-44780 Bochum, Germany.
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Basmarke-Wehelie R, Sjölinder H, Jurkowski W, Elofsson A, Arnqvist A, Engstrand L, Hagner M, Wallin E, Guan N, Kuranasekera H, Aro H, Jonsson AB. The complement regulator CD46 is bactericidal to Helicobacter pylori and blocks urease activity. Gastroenterology 2011; 141:918-28. [PMID: 21699774 DOI: 10.1053/j.gastro.2011.05.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 04/28/2011] [Accepted: 05/06/2011] [Indexed: 12/28/2022]
Abstract
BACKGROUND & AIMS CD46 is a C3b/C4b binding complement regulator and a receptor for several human pathogens. We examined the interaction between CD46 and Helicobacter pylori (a bacterium that colonizes the human gastric mucosa and causes gastritis), peptic ulcers, and cancer. METHODS Using gastric epithelial cells, we analyzed a set of H pylori strains and mutants for their ability to interact with CD46 and/or influence CD46 expression. Bacterial interaction with full-length CD46 and small CD46 peptides was evaluated by flow cytometry, fluorescence microscopy, enzyme-linked immunosorbent assay, and bacterial survival analyses. RESULTS H pylori infection caused shedding of CD46 into the extracellular environment. A soluble form of CD46 bound to H pylori and inhibited growth, in a dose- and time-dependent manner, by interacting with urease and alkyl hydroperoxide reductase, which are essential bacterial pathogenicity-associated factors. Binding of CD46 or CD46-derived synthetic peptides blocked the urease activity and ability of bacteria to survive in acidic environments. Oral administration of one CD46 peptide eradicated H pylori from infected mice. CONCLUSIONS CD46 is an antimicrobial agent that can eradicate H pylori. CD46 peptides might be developed to treat H pylori infection.
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Affiliation(s)
- Rahma Basmarke-Wehelie
- Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden
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Inhibition of Helicobacter pylori adhesion to Kato III cells by intact and low molecular weight acharan sulfate. Glycoconj J 2011; 28:411-8. [DOI: 10.1007/s10719-011-9340-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Revised: 06/14/2011] [Accepted: 06/15/2011] [Indexed: 01/24/2023]
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20
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Helicobacter pylori VacA induces programmed necrosis in gastric epithelial cells. Infect Immun 2011; 79:2535-43. [PMID: 21482684 DOI: 10.1128/iai.01370-10] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Helicobacter pylori is a Gram-negative bacterium that colonizes the human stomach and contributes to the development of peptic ulcer disease and gastric cancer. The secreted pore-forming toxin VacA is one of the major virulence factors of H. pylori. In the current study, we show that AZ-521 human gastric epithelial cells are highly susceptible to VacA-induced cell death. Wild-type VacA causes death of these cells, whereas mutant VacA proteins defective in membrane channel formation do not. Incubation of AZ-521 cells with wild-type VacA results in cell swelling, poly(ADP-ribose) polymerase (PARP) activation, decreased intracellular ATP concentration, and lactate dehydrogenase (LDH) release. VacA-induced death of these cells is a caspase-independent process that results in cellular release of histone-binding protein high mobility group box 1 (HMGB1), a proinflammatory protein. These features are consistent with the occurrence of cell death through a programmed necrosis pathway and suggest that VacA can be included among the growing number of bacterial pore-forming toxins that induce cell death through programmed necrosis. We propose that VacA augments H. pylori-induced mucosal inflammation in the human stomach by causing programmed necrosis of gastric epithelial cells and subsequent release of proinflammatory proteins and may thereby contribute to the pathogenesis of gastric cancer and peptic ulceration.
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Ricci V, Romano M, Boquet P. Molecular cross-talk between Helicobacter pylori and human gastric mucosa. World J Gastroenterol 2011; 17:1383-99. [PMID: 21472096 PMCID: PMC3070011 DOI: 10.3748/wjg.v17.i11.1383] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 12/19/2010] [Accepted: 12/26/2010] [Indexed: 02/06/2023] Open
Abstract
Helicobacter pylori (H. pylori) has co-evolved with humans to be transmitted from person to person and to colonize the stomach persistently. A well-choreographed equilibrium between the bacterial effectors and host responses permits microbial persistence and health of the host, but confers a risk for serious diseases including gastric cancer. During its long coexistence with humans, H. pylori has developed complex strategies to limit the degree and extent of gastric mucosal damage and inflammation, as well as immune effector activity. The present editorial thus aims to introduce and comment on major advances in the rapidly developing area of H. pylori/human gastric mucosa interaction (and its pathological sequelae), which is the result of millennia of co-evolution of, and thus of reciprocal knowledge between, the pathogen and its human host.
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Namba T, Hoshino T, Suemasu S, Takarada-Iemata M, Hori O, Nakagata N, Yanaka A, Mizushima T. Suppression of expression of endoplasmic reticulum chaperones by Helicobacter pylori and its role in exacerbation of non-steroidal anti-inflammatory drug-induced gastric lesions. J Biol Chem 2010; 285:37302-13. [PMID: 20861013 DOI: 10.1074/jbc.m110.148882] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Both the use of non-steroidal anti-inflammatory drugs (NSAIDs), such as indomethacin, and infection with Helicobacter pylori are major causes of gastric ulcers. Although some clinical studies suggest that infection with H. pylori increases the risk of developing NSAID-induced gastric lesions, the molecular mechanism governing this effect is unknown. We recently found that in cultured gastric cells, expression of endoplasmic reticulum (ER) chaperones (such as 150-kDa oxygen-regulated protein (ORP150) and glucose-regulated protein 78 (GRP78)) is induced by NSAIDs and confers protection against NSAID-induced apoptosis, which is important in the development of NSAID-induced gastric lesions. In this study we have found that co-culture of gastric cells with H. pylori suppresses the expression of ER chaperones. This suppression was regulated at the level of transcription and accompanied by a reduction in the level of activating transcription factor 6 (ATF6), one of the transcription factors for ER chaperone genes. In vivo, inoculation of mice with H. pylori suppressed the expression of ER chaperones at gastric mucosa both with and without administration of indomethacin. Inoculation with H. pylori also stimulated formation of indomethacin-induced gastric lesions and mucosal cell death. In addition, we found that heterozygous ORP150-deficient mice are sensitive to the development of indomethacin-induced gastric lesions and mucosal cell death. The results of this study suggest that H. pylori exacerbates NSAID-induced gastric lesions through suppression of expression of ER chaperones, which stimulates NSAID-induced mucosal cell death.
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Affiliation(s)
- Takushi Namba
- Graduate School of Medical and Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973, USA
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Abstract
Several bacterial pathogens inject virulence proteins into host target cells that are substrates of eukaryotic tyrosine kinases. One of the key examples is the Helicobacter pylori CagA effector protein which is translocated by a type-IV secretion system. Injected CagA becomes tyrosine-phosphorylated on EPIYA sequence motifs by Src and Abl family kinases. CagA then binds to and activates/inactivates multiple signaling proteins in a phosphorylation-dependent and phosphorylation-independent manner. A recent proteomic screen systematically identified eukaryotic binding partners of the EPIYA phosphorylation sites of CagA and similar sites in other bacterial effectors by high-resolution mass spectrometry. Individual phosphorylation sites recruited a surprisingly high number of interaction partners suggesting that each phosphorylation site can interfere with many downstream pathways. We now count 20 reported cellular binding partners of CagA, which represents the highest quantitiy among all yet known virulence-associated effector proteins in the microbial world. This complexity generates a highly remarkable and puzzling scenario. In addition, the first crystal structure of CagA provided us with new information on the function of this important virulence determinant. Here we review the recent advances in characterizing the multiple binding signaling activities of CagA. Injected CagA can act as a 'master key' that evolved the ability to highjack multiple host cell signalling cascades, which include the induction of membrane dynamics, actin-cytoskeletal rearrangements and the disruption of cell-to-cell junctions as well as proliferative, pro-inflammatory and anti-apoptotic nuclear responses. The discovery that different pathogens use this common strategy to subvert host cell functions suggests that more examples will emerge soon.
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Calore F, Genisset C, Casellato A, Rossato M, Codolo G, Esposti MD, Scorrano L, de Bernard M. Endosome-mitochondria juxtaposition during apoptosis induced by H. pylori VacA. Cell Death Differ 2010; 17:1707-16. [PMID: 20431599 DOI: 10.1038/cdd.2010.42] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The vacuolating cytotoxin (VacA) is an important virulence factor of Helicobacter pylori with pleiotropic effects on mammalian cells, including the ability to trigger mitochondria-dependent apoptosis. However, the mechanism by which VacA exerts its apoptotic function is unclear. Using a genetic approach, in this study we show that killing by VacA requires the proapoptotic Bcl-2 family members BAX and BAK at the mitochondrial level, but not adequate endoplasmic reticulum Ca²(+) levels, similarly controlled by BAX and BAK. A combination of subcellular fractionation and imaging shows that wild-type VacA, but not mutants in its channel-forming region, induces the accumulation of BAX on endosomes and endosome-mitochondria juxtaposition that precedes the retrieval of active BAX on mitochondria. It is noteworthy that in Bax- and Bak-deficient cells, VacA is unable to cause endosome-mitochondria juxtaposition and is not retrieved in mitochondria. Thus, VacA causes BAX/BAK-dependent juxtaposition of endosomes and mitochondria early in the process of cell death, revealing a new function for these proapoptotic proteins in the regulation of relative position of organelles.
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Affiliation(s)
- F Calore
- Venetian Institute of Molecular Medicine, Padova, Italy
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25
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Domańska G, Motz C, Meinecke M, Harsman A, Papatheodorou P, Reljic B, Dian-Lothrop EA, Galmiche A, Kepp O, Becker L, Günnewig K, Wagner R, Rassow J. Helicobacter pylori VacA toxin/subunit p34: targeting of an anion channel to the inner mitochondrial membrane. PLoS Pathog 2010; 6:e1000878. [PMID: 20442789 PMCID: PMC2861713 DOI: 10.1371/journal.ppat.1000878] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Accepted: 03/25/2010] [Indexed: 12/13/2022] Open
Abstract
The vacuolating toxin VacA, released by Helicobacter pylori, is an important virulence factor in the pathogenesis of gastritis and gastroduodenal ulcers. VacA contains two subunits: The p58 subunit mediates entry into target cells, and the p34 subunit mediates targeting to mitochondria and is essential for toxicity. In this study we found that targeting to mitochondria is dependent on a unique signal sequence of 32 uncharged amino acid residues at the p34 N-terminus. Mitochondrial import of p34 is mediated by the import receptor Tom20 and the import channel of the outer membrane TOM complex, leading to insertion of p34 into the mitochondrial inner membrane. p34 assembles in homo-hexamers of extraordinary high stability. CD spectra of the purified protein indicate a content of >40% beta-strands, similar to pore-forming beta-barrel proteins. p34 forms an anion channel with a conductivity of about 12 pS in 1.5 M KCl buffer. Oligomerization and channel formation are independent both of the 32 uncharged N-terminal residues and of the p58 subunit of the toxin. The conductivity is efficiently blocked by 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), a reagent known to inhibit VacA-mediated apoptosis. We conclude that p34 essentially acts as a small pore-forming toxin, targeted to the mitochondrial inner membrane by a special hydrophobic N-terminal signal.
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Affiliation(s)
- Grażyna Domańska
- Institut für Physiologische Chemie, Ruhr-Universität Bochum, Bochum, Germany
| | - Christian Motz
- Institut für Physiologische Chemie, Ruhr-Universität Bochum, Bochum, Germany
| | - Michael Meinecke
- Institut für Biophysik, Universität Osnabrück, Osnabrück, Germany
| | - Anke Harsman
- Institut für Biophysik, Universität Osnabrück, Osnabrück, Germany
| | | | - Boris Reljic
- Institut für Physiologische Chemie, Ruhr-Universität Bochum, Bochum, Germany
| | | | - Antoine Galmiche
- Laboratoire de Biochimie, INSERM ERI12, Hopital Nord, CHU Amiens Picardie, Amiens, France
| | - Oliver Kepp
- INSERM U848, Institute Gustave Roussy, Université Paris Sud, Villejuif, France
| | - Lars Becker
- Institut für Biophysik, Universität Osnabrück, Osnabrück, Germany
| | - Kathrin Günnewig
- Institut für Physiologische Chemie, Ruhr-Universität Bochum, Bochum, Germany
| | - Richard Wagner
- Institut für Biophysik, Universität Osnabrück, Osnabrück, Germany
| | - Joachim Rassow
- Institut für Physiologische Chemie, Ruhr-Universität Bochum, Bochum, Germany
- * E-mail:
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Lan CH, Sheng JQ, Fang DC, Meng QZ, Fan LL, Huang ZR. Involvement of VDAC1 and Bcl-2 family of proteins in VacA-induced cytochrome c release and apoptosis of gastric epithelial carcinoma cells. J Dig Dis 2010; 11:43-9. [PMID: 20132430 DOI: 10.1111/j.1751-2980.2009.00412.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE It is known that the vacuolating cytotoxin (VacA) could induce apoptosis. However, the mechanism remained to be elucidated. The aim of this study is to investigate the role of Bcl family of proteins (Bcl-2 and Bax) and the mitochondrial voltage-dependent anion channel (VDAC) in VacA-induced apoptosis of AGS cells. METHODS Plasmid pGBKT7-VacA p58 was constructed and transfected into the AGS cells. RT-PCR and Western blotting were used to determine the expressions of cytochrome c, caspase-3, Bax, Bcl-2 and VDAC1 mRNA and proteins. RESULTS VacA p58 can induce cytochrome c release and activate caspase-3 in AGS cells. It up-regulated the expressions of Bax and VDAC1 mRNA and proteins, and decreased the expression of Bcl-2 in AGS cells. CONCLUSION VacA p58 induces apoptosis in AGS cells. This apoptotic process is associated with the up-regulation of Bax/VDAC1 and downregulation of Bcl-2. These findings suggest that the release of cytochrome c by VacA p58 is mainly through VDAC-dependent and Bcl-2 family-dependent pathways.
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Affiliation(s)
- Chun Hui Lan
- Department of Gastroenterology, Daping Hospital, Third Military Medical College, Chongqing, China.
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Backert S, Tegtmeyer N. the versatility of the Helicobacter pylori vacuolating cytotoxin vacA in signal transduction and molecular crosstalk. Toxins (Basel) 2010; 2:69-92. [PMID: 22069547 PMCID: PMC3206623 DOI: 10.3390/toxins2010069] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 12/31/2009] [Accepted: 01/14/2010] [Indexed: 12/13/2022] Open
Abstract
By modulating important properties of eukaryotic cells, many bacterial protein toxins highjack host signalling pathways to create a suitable niche for the pathogen to colonize and persist. Helicobacter pylori VacA is paradigm of pore-forming toxins which contributes to the pathogenesis of peptic ulceration. Several cellular receptors have been described for VacA, which exert different effects on epithelial and immune cells. The crystal structure of VacA p55 subunit might be important for elucidating details of receptor interaction and pore formation. Here we discuss the multiple signalling activities of this important toxin and the molecular crosstalk between VacA and other virulence factors.
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Affiliation(s)
- Steffen Backert
- Ardmore House, School of Biomolecular and Biomedical Sciences, Belfield Campus, University College Dublin, Dublin-4, Ireland.
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28
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Effects of Helicobacter pylori infection on the expressions of Bax and Bcl-2 in patients with chronic gastritis and gastric cancer. Dig Dis Sci 2010; 55:111-6. [PMID: 19160045 DOI: 10.1007/s10620-008-0699-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 12/30/2008] [Indexed: 12/21/2022]
Abstract
The aim of the present study is to evaluate the influence of Helicobacter pylori on Bax and Bcl-2 mRNA and protein levels in patients with chronic gastritis and gastric cancer. The study included 217 patients, of which 26 were uninfected; 127 had chronic gastritis and were H. pylori-positive, and 64 had gastric cancer. Bacterial genotypes were evaluated by PCR, and the expression values were determined by quantitative real-time PCR and immunohistochemistry. Our data showed that the up-regulationary effects of H. pylori infection on the pro-apoptotic gene, Bax, were stronger than its induction of Bcl-2; this effect may increase apoptosis in patients with chronic gastritis. In patients with gastric cancer, the up-regulation of the anti-apoptotic gene, Bcl-2, counteracted the pro-apoptotic effects of Bax, leading to a deregulation of apoptosis-associated gene expression, favoring cell proliferation. Thus, the disturbance in Bax and Bcl-2 balance, induced by H. pylori, might be important in gastric cancer development.
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Galmiche A, Rassow J. Targeting of Helicobacter pylori VacA to mitochondria. Gut Microbes 2010; 1:392-5. [PMID: 21468222 PMCID: PMC3056105 DOI: 10.4161/gmic.1.6.13894] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 10/04/2010] [Accepted: 10/08/2010] [Indexed: 02/03/2023] Open
Abstract
One of the major virulence factors of Helicobacter pylori is the vacuolating toxin vaca. It has been known for a long time that the toxin enters host cells by endocytosis. On the other hand there is ample evidence that vaca is able to trigger apoptosis and this effect has been attributed in part to interactions with mitochondria. However, for 10 years it was difficult to reconcile the obvious accumulation of vaca in endosomes with mitochondrial targeting. The accessibility of the mitochondria to the toxin was enigmatic. In our new study, we investigated the activities of p34, the toxic subunit of vaca, in more detail. We found that the p34 N-terminus carries a unique targeting sequence for import into mitochondria and for insertion into the mitochondrial inner membrane. By forming an anion channel in this membrane, the toxin has the ability to interfere directly with mitochondrial functions. Taking into account additional results from independent studies, we discuss the implications of our findings with respect to intracellular traffic, the remarkable possibility of a direct transfer of VacA from endosomes to mitochondria and vaca-dependent cell death.
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Affiliation(s)
- Antoine Galmiche
- Laboratoire de Biochimie Inserm ERI12; Hopital Nord; CHU Amiens Picardie; Amiens Cedex 1, France
| | - Joachim Rassow
- Institut für Physiologische Chemie; Ruhr-Universität Bochum; Bochum, Germany
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Helicobacter pylori counteracts the apoptotic action of its VacA toxin by injecting the CagA protein into gastric epithelial cells. PLoS Pathog 2009; 5:e1000603. [PMID: 19798427 PMCID: PMC2745580 DOI: 10.1371/journal.ppat.1000603] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Accepted: 09/04/2009] [Indexed: 12/14/2022] Open
Abstract
Infection with Helicobacter pylori is responsible for gastritis and gastroduodenal ulcers but is also a high risk factor for the development of gastric adenocarcinoma and lymphoma. The most pathogenic H. pylori strains (i.e., the so-called type I strains) associate the CagA virulence protein with an active VacA cytotoxin but the rationale for this association is unknown. CagA, directly injected by the bacterium into colonized epithelium via a type IV secretion system, leads to cellular morphological, anti-apoptotic and proinflammatory effects responsible in the long-term (years or decades) for ulcer and cancer. VacA, via pinocytosis and intracellular trafficking, induces epithelial cell apoptosis and vacuolation. Using human gastric epithelial cells in culture transfected with cDNA encoding for either the wild-type 38 kDa C-terminal signaling domain of CagA or its non-tyrosine-phosphorylatable mutant form, we found that, depending on tyrosine-phosphorylation by host kinases, CagA inhibited VacA-induced apoptosis by two complementary mechanisms. Tyrosine-phosphorylated CagA prevented pinocytosed VacA to reach its target intracellular compartments. Unphosphorylated CagA triggered an anti-apoptotic activity blocking VacA-induced apoptosis at the mitochondrial level without affecting the intracellular trafficking of the toxin. Assaying the level of apoptosis of gastric epithelial cells infected with wild-type CagA+/VacA+H. pylori or isogenic mutants lacking of either CagA or VacA, we confirmed the results obtained in cells transfected with the CagA C-ter constructions showing that CagA antagonizes VacA-induced apoptosis. VacA toxin plays a role during H. pylori stomach colonization. However, once bacteria have colonized the gastric niche, the apoptotic action of VacA might be detrimental for the survival of H. pylori adherent to the mucosa. CagA association with VacA is thus a novel, highly ingenious microbial strategy to locally protect its ecological niche against a bacterial virulence factor, with however detrimental consequences for the human host. The gram-negative bacterium Helicobacter pylori is the main causative agent of peptic ulcer and gastric cancer in humans. Our work sheds light on a new molecular mechanism by which H. pylori would exert its highly efficient colonization strategy of the human host. In this paper, we show that the H. pylori CagA protein counteracts, by two distinct non-overlapping mechanisms, the apoptotic activity of the H. pylori VacA toxin on human gastric epithelial cells so as to allow a protection of the bacterium niche against VacA, giving a rationale for the association of these two virulence factors in the most pathogenic H. pylori strains. This is a new, highly ingenious mechanism by which a bacterium locally protects its ecological niche against the action of one of its own virulence factors. However, while exerting a beneficial role for survival and growth of the bacterium by counteracting VacA toxin, CagA injection in the gastric epithelial cells triggers proinflammatory and anti-apoptotic responses which are detrimental for the human host in the long-term and favor the development of ulcer and cancer.
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31
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Varon C, Mosnier JF, Lehours P, Matysiak-Budnik T, Mégraud F. Gastric carcinogenesis and Helicobacter pylori infection. Methods Mol Biol 2009; 511:237-65. [PMID: 19347300 DOI: 10.1007/978-1-59745-447-6_10] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Helicobacter pylori is the most frequent cause of infection-induced cancer worldwide. Gastric carcino-genesis is the consequence of the important and life-long inflammation induced by H. pylori in the stomach. Gastric carcinogenesis, can be studied in many ways. In this chapter, we focus on some aspects concerning the bacteria, and others concerning the host. On the bacterial side, the methods exploring the presence of the cag pathogenicity island including cagA and the consequences on epithelial cells are presented. On the host side, tissue microarray, immunohistochemistry and chromogenic in situ hybridization (CISH) are described.
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Bergsbaken T, Cookson BT. Macrophage activation redirects yersinia-infected host cell death from apoptosis to caspase-1-dependent pyroptosis. PLoS Pathog 2008; 3:e161. [PMID: 17983266 PMCID: PMC2048529 DOI: 10.1371/journal.ppat.0030161] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Accepted: 09/17/2007] [Indexed: 02/07/2023] Open
Abstract
Infection of macrophages by Yersinia species results in YopJ-dependent apoptosis, and naïve macrophages are highly susceptible to this form of cell death. Previous studies have demonstrated that macrophages activated with lipopolysaccharide (LPS) prior to infection are resistant to YopJ-dependent cell death; we found this simultaneously renders macrophages susceptible to killing by YopJ−Yersinia pseudotuberculosis (Yptb). YopJ−Yptb-induced macrophage death was dependent on caspase-1 activation, resulting in rapid permeability to small molecules, followed by membrane breakdown and DNA damage, and accompanied by cleavage and release of proinflammatory interleukin-18. Induction of caspase-1-dependent death, or pyroptosis, required the bacterial type III translocon but none of its known translocated proteins. Wild-type Yptb infection also triggered pyroptosis: YopJ-dependent activation of proapoptotic caspase-3 was significantly delayed in activated macrophages and resulted in caspase-1-dependent pyroptosis. The transition to susceptibility was not limited to LPS activation; it was also seen in macrophages activated with other Toll-like receptor (TLR) ligands and intact nonviable bacteria. Yptb infection triggered macrophage activation and activation of caspase-1 in vivo. Y. pestis infection of activated macrophages also stimulated caspase-1 activation. These results indicate that host signaling triggered by TLR and other activating ligands during the course of Yersinia infection redirects both the mechanism of host cell death and the downstream consequences of death by shifting from noninflammatory apoptosis to inflammatory pyroptosis. Pathogenic Yersinia are bacteria capable of interacting with host immune cells and inhibiting their function. Macrophages are potent antimicrobial immune cells that eliminate invading microbes, and represent a major target for Yersinia during infection. Yersinia triggers death of resting macrophages by apoptosis, a process thought to be advantageous for Yersinia growth during early stages of infection because important host cells are eliminated without perturbing the surrounding tissue. However, activated macrophages with enhanced antimicrobial activity play a crucial role in controlling Yersinia infection. To elucidate the mechanisms involved in successful defense against infection, the authors investigated the response of activated macrophages to Yersinia, which revealed induction of a proinflammatory cell death pathway termed pyroptosis. Unlike apoptosis, pyroptosis unleashes inflammatory mediators capable of enhancing immune responses and clearing bacteria. Macrophage activation and pyroptosis was observed in infected host tissue. Thus, regulating the mechanism of cell death is important for effective responses to Yersinia infection: activated macrophages resisting apoptosis are redirected to utilize pyroptosis, an inflammatory process facilitating host resistance.
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Affiliation(s)
- Tessa Bergsbaken
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Brad T Cookson
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
- Department of Laboratory Medicine, University of Washington, Seattle, Washington, United States of America
- * To whom correspondence should be addressed. E-mail:
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Mimuro H, Suzuki T, Nagai S, Rieder G, Suzuki M, Nagai T, Fujita Y, Nagamatsu K, Ishijima N, Koyasu S, Haas R, Sasakawa C. Helicobacter pylori dampens gut epithelial self-renewal by inhibiting apoptosis, a bacterial strategy to enhance colonization of the stomach. Cell Host Microbe 2007; 2:250-63. [PMID: 18005743 DOI: 10.1016/j.chom.2007.09.005] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Revised: 08/11/2007] [Accepted: 09/14/2007] [Indexed: 02/06/2023]
Abstract
Colonization of the gastric pits in the stomach by Helicobacter pylori (Hp) is a major risk factor for gastritis, gastric ulcers, and cancer. Normally, rapid self-renewal of gut epithelia, which occurs by a balance of progenitor proliferation and pit cell apoptosis, serves as a host defense mechanism to limit bacterial colonization. To investigate how Hp overcomes this host defense, we use the Mongolian gerbil model of Hp infection. Apoptotic loss of pit cells induced by a proapoptotic agent is suppressed by Hp. The ability of Hp to suppress apoptosis contributed to pit hyperplasia and persistent bacterial colonization of the stomach. Infection with WT Hp but not with a mutant in the virulence effector cagA increased levels of the prosurvival factor phospho-ERK and antiapoptotic protein MCL1 in the gastric pits. Thus, CagA activates host cell survival and antiapoptotic pathways to overcome self-renewal of the gastric epithelium and help sustain Hp infection.
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Affiliation(s)
- Hitomi Mimuro
- Department of Microbiology and Immunology, Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
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34
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Owen RJ, Xerry J. Geographical conservation of short inserts in the signal and middle regions of the Helicobacter pylori vacuolating cytotoxin gene. MICROBIOLOGY-SGM 2007; 153:1176-1186. [PMID: 17379727 DOI: 10.1099/mic.0.2006/002923-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Short nucleotide sequence inserts within the signal (s) and mid (m) regions of the vacuolating cytotoxin gene (vacA) of Helicobacter pylori provide the basis for defining the allelic forms widely used for strain typing and as markers for toxin functionality and severity of interactions with host gastric epithelial cells. Here 484 signal region and 411 mid-region sequences (new and from public databases) from 32 countries were analysed to determine the effect of geographical location on insert diversity, which is currently undefined. Short (27 bp) inserts of 52 mol% G+C from 201 sequences (98 %) of the s2 allelic family encoded a highly conserved nine amino acid sequence irrespective of geographical origin. The longer (75 bp) mid-region insert of 38 mol% G+C in 255 sequences of the m2 allelic family was more diverse and represented by 23 peptide variants, with one predominant sequence (MRI type 4) representing 62 % of inserts. Mid-region inserts were widespread throughout European/North American (Western) sequences in the dataset whereas a lower insert frequency was a geographical feature of East Asian sequences. Each insert was preceded by an associated conserved motif that provided a marker of the insertion sites within vacA, and facilitated identification of the Chinese m2b genotype. It is concluded that the observed sequence conservation supports the continued global use of vacA genotyping, and that inserts could have a functional significance in the mature protein, particularly the s2 form of the toxin, as the same combination of signal and mid-region insert type and preinsert motif was highly conserved.
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Affiliation(s)
- Robert J Owen
- Campylobacter and Helicobacter Research/Reference Unit, Laboratory of Enteric Pathogens, Centre for Infections, Health Protection Agency, 61 Colindale Avenue, London NW9 5HT, UK
| | - Jacqueline Xerry
- Campylobacter and Helicobacter Research/Reference Unit, Laboratory of Enteric Pathogens, Centre for Infections, Health Protection Agency, 61 Colindale Avenue, London NW9 5HT, UK
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35
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Laux MT, Aregullin M, Rodriguez E. Inhibition of Helicobacter pylori and Gastric Cancer Cells by Lipid Aldehydes from Viburnum opulus (Adoxaceae). Nat Prod Commun 2007. [DOI: 10.1177/1934578x0700201009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
A unique group of bioactive, naturally occurring lipid aldehydes were isolated from the fruits of Viburnum opulus, (family Adoxaceae). The natural occurrences of these fatty acid derived aldehydes are reported here for the first time. Helicobacter pylori is a prevalent gastroduodenal pathogen, a causal agent of chronic gastritis and peptic ulcers and an important co-factor in gastric cancer development. We investigated the chemistry and bioactivity of these active constituents by evaluating their ability to inhibit the growth of H. pylori and to induce apoptosis in a gastric cancer cell line (CRL-5971) in vitro.
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Affiliation(s)
- Maria Teresa Laux
- College of Veterinary Medicine, Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Manuel Aregullin
- College of Agriculture and Life Science, Department of Molecular Biology & Genetics, Ithaca, NY 14853, USA
| | - Eloy Rodriguez
- Department of Plant Biology, Cornell University, Ithaca, NY 14853, USA
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36
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Gauthier NC, Monzo P, Gonzalez T, Doye A, Oldani A, Gounon P, Ricci V, Cormont M, Boquet P. Early endosomes associated with dynamic F-actin structures are required for late trafficking of H. pylori VacA toxin. ACTA ACUST UNITED AC 2007; 177:343-54. [PMID: 17438076 PMCID: PMC2064141 DOI: 10.1083/jcb.200609061] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Glycosylphosphatidylinositol-anchored proteins (GPI-APs) are endocytosed by a clathrin- independent pathway into vesicles named GPI-AP–enriched early endosomal compartments (GEECs). We recently showed that the vacuolating toxin VacA secreted by Helicobacter pylori is endocytosed into the GEECs (Gauthier, N.C., P. Monzo, V. Kaddai, A. Doye, V. Ricci, and P. Boquet. 2005. Mol. Biol. Cell. 16:4852–4866). Unlike GPI-APs that are mostly recycled back to the plasma membrane, VacA reaches early endosomes (EEs) and then late endosomes (LEs), where vacuolation occurs. In this study, we used VacA to study the trafficking pathway between GEECs and LEs. We found that VacA routing from GEECs to LEs required polymerized actin. During this trafficking, VacA was transferred from GEECs to EEs associated with polymerized actin structures. The CD2-associated protein (CD2AP), a docking protein implicated in intracellular trafficking, bridged the filamentous actin (F-actin) structures with EEs containing VacA. CD2AP regulated those F-actin structures and was required to transfer VacA from GEECs to LEs. These results demonstrate that sorting from GEECs to LEs requires dynamic F-actin structures on EEs.
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Affiliation(s)
- Nils C Gauthier
- Unité 627 and 2Unité 568, Institut National de la Santé et de la Recherche Medicale, Faculty of Medicine, 06107 Nice, Cedex 02, France
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37
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Matarrese P, Falzano L, Fabbri A, Gambardella L, Frank C, Geny B, Popoff MR, Malorni W, Fiorentini C. Clostridium difficile toxin B causes apoptosis in epithelial cells by thrilling mitochondria. Involvement of ATP-sensitive mitochondrial potassium channels. J Biol Chem 2007; 282:9029-41. [PMID: 17220295 DOI: 10.1074/jbc.m607614200] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Targeting to mitochondria is emerging as a common strategy that bacteria utilize to interact with these central executioners of apoptosis. Several lines of evidence have in fact indicated mitochondria as specific targets for bacterial protein toxins, regarded as the principal virulence factors of pathogenic bacteria. This work shows, for the first time, the ability of the Clostridium difficile toxin B (TcdB), a glucosyltransferase that inhibits the Rho GTPases, to impact mitochondria. In living cells, TcdB provokes an early hyperpolarization of mitochondria that follows a calcium-associated signaling pathway and precedes the final execution step of apoptosis (i.e. mitochondria depolarization). Importantly, in isolated mitochondria, the toxin can induce a calcium-dependent mitochondrial swelling, accompanied by the release of the proapoptogenic factor cytochrome c. This is consistent with a mitochondrial targeting that does not require the Rho-inhibiting activity of the toxin. Of interest, the mitochondrial ATP-sensitive potassium channels are also involved in the apoptotic response to TcdB and appear to be crucial for the cell death execution phase, as demonstrated by using specific modulators of these channels. To our knowledge, the involvement of these mitochondrial channels in the ability of a bacterial toxin to control cell fate is a hitherto unreported finding.
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Affiliation(s)
- Paola Matarrese
- Department of Drug Research and Evaluation, Istituto Superiore di Sanita', Viale Regina Elena 299, 00161 Rome, Italy
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Brest P, Hofman V, Lassalle S, Césaro A, Ricci V, Selva E, Auberger P, Hofman P. Human polymorphonuclear leukocytes are sensitive in vitro to Helicobacter pylori vaca toxin. Helicobacter 2006; 11:544-55. [PMID: 17083376 DOI: 10.1111/j.1523-5378.2006.00457.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Interactions between bacterial components and polymorphonuclear leukocytes (PMNL) play a major pathogenic role in Helicobacter pylori-associated diseases. Activation of PMNL can be induced by contact with whole bacteria or by different H. pylori products released in the extracellular space either by active secretion or by bacterial autolysis. Among these products, H. pylori VacA is a secreted toxin inducing vacuolation and apoptosis of epithelial cells. METHODS AND RESULTS We found that non-opsonic human PMNL were sensitive to the vacuolating effect of VacA+ broth culture filtrate (BCF) and of purified VacA toxin. PMNL incubated with VacA+ BCF showed Rab7-positive large intracytoplasmic vacuoles. PMNL preincubation with H. pylori BCF of different phenotypes dramatically potentialized the oxidative burst induced by zymosan, increased phagocytosis of opsonized fluorescent beads, and up-regulated CD11b cell surface expression, but independently of the BCF VacA phenotype. Moreover, by using purified VacA toxin we showed that vacuolation induced in PMNL did not modify the rate of spontaneous PMNL apoptosis measured by caspase 3 activity. CONCLUSIONS Taken together, these data showed that human PMNL is a sensitive cell population to H. pylori VacA toxin. However, activation of PMNL (i.e., oxidative burst, phagocytosis, CD11b up-regulation) and PMNL apoptosis are not affected by VacA, raising question about the role of VacA toxin on PMNL in vivo.
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Affiliation(s)
- Patrick Brest
- INSERM ERI-21, Pasteur'Hospital and Faculty of Medicine, University of Nice, Nice, France
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39
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Romano M, Ricci V, Zarrilli R. Mechanisms of Disease: Helicobacter pylori-related gastric carcinogenesis—implications for chemoprevention. ACTA ACUST UNITED AC 2006; 3:622-32. [PMID: 17068500 DOI: 10.1038/ncpgasthep0634] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2006] [Accepted: 08/04/2006] [Indexed: 02/06/2023]
Abstract
Gastric adenocarcinoma is the second most common cause of cancer-related mortality worldwide. Infection with Helicobacter pylori is the single most common cause of adenocarcinoma of the distal stomach. Cancer risk is believed to be related to differences among H. pylori strains and inflammatory responses governed by host genetics. In particular, specific interactions between host factors that modulate the response to the infection, and bacterial virulence factors that can directly cause tissue damage seem to have a major pathogenic role in the development of gastric cancer. In addition, environmental factors can modify key growth signaling pathways within the gastric mucosa, which leads to the alteration of epithelial cell growth. Preventive strategies represent the most promising means of decreasing cancer risk, and must be aimed at the control of H. pylori infection, improvement of environmental conditions, and the identification of subjects who are genetically predisposed to the development of cancer in response to H. pylori infection. Understanding the intracellular signaling pathways that are specifically affected by H. pylori and that promote phenotypic and genotypic changes that might ultimately progress to malignant transformation could enable physicians to focus eradication therapy appropriately and design interventions targeted at the molecular level to prevent the development of gastric cancer.
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Affiliation(s)
- Marco Romano
- Dipartimento di Internistica Clinica e Sperimentale A Lanzara e F Magrassi--Gastroenterologia e CIRANAD, Seconda Università di Napoli, II Policlinico, Ed 3, Secondo piano, Via Pansini 5, 80131 Napoli, Italy.
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Nakayama M, Hisatsune J, Yamasaki E, Nishi Y, Wada A, Kurazono H, Sap J, Yahiro K, Moss J, Hirayama T. Clustering of Helicobacter pylori VacA in lipid rafts, mediated by its receptor, receptor-like protein tyrosine phosphatase beta, is required for intoxication in AZ-521 Cells. Infect Immun 2006; 74:6571-80. [PMID: 17030583 PMCID: PMC1698068 DOI: 10.1128/iai.00356-06] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Helicobacter pylori vacuolating cytotoxin, VacA, induces multiple effects on epithelial cells through different cellular events: one involves pore formation, leading to vacuolation, mitochondrial damage, and apoptosis, and the second involves cell signaling, resulting in stimulation of proinflammatory responses and cell detachment. Our recent data demonstrated that VacA uses receptor-like protein tyrosine phosphatase beta (RPTPbeta) as a receptor, of which five residues (QTTQP) at positions 747 to 751 are involved in binding. In AZ-521 cells, which mainly express RPTPbeta, VacA, after binding to RPTPbeta in non-lipid raft microdomains on the cell surface, is localized with RPTPbeta in lipid rafts in a temperature- and VacA concentration-dependent process. Methyl-beta-cyclodextrin (MCD) did not block binding to RPTPbeta but inhibited translocation of VacA with RPTPbeta to lipid rafts and all subsequent events. On the other hand, 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), which disrupts anion channels, did not inhibit translocation of VacA to lipid rafts or VacA-induced activation of p38 mitogen-activated protein (MAP) kinase, but inhibited VacA internalization followed by vacuolation. Thus, p38 MAP kinase activation did not appear to be required for internalization. In contrast, phosphatidylinositol-specific phospholipase C (PI-PLC) inhibited translocation, as well as p38 MAP kinase/ATF-2 activation, internalization, and VacA-induced vacuolation. Neither NPPB nor PI-PLC affected VacA binding to cells and to its receptor, RPTPbeta. Thus, receptor-dependent translocation of VacA to lipid rafts is critical for signaling pathways leading to p38 MAP kinase/ATF-2 activation and vacuolation.
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Affiliation(s)
- Masaaki Nakayama
- Department of Bacteriology, Institute of Tropical Medicine, Nagasaki University, Nagasaki 8528523, Japan
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41
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Yamasaki E, Wada A, Kumatori A, Nakagawa I, Funao J, Nakayama M, Hisatsune J, Kimura M, Moss J, Hirayama T. Helicobacter pylori vacuolating cytotoxin induces activation of the proapoptotic proteins Bax and Bak, leading to cytochrome c release and cell death, independent of vacuolation. J Biol Chem 2006; 281:11250-9. [PMID: 16436379 DOI: 10.1074/jbc.m509404200] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Helicobacter pylori vacuolating cytotoxin, VacA, which causes vacuolation of gastric epithelial cells and other types of cultured cells, is known to stimulate apoptosis via a mitochondria-dependent pathway. In the present study, we examined the mechanisms of VacA-induced mitochondrial damage. Intracellular VacA localization was monitored by immunostaining and confocal microscopy; in AZ-521 cells in which cytochrome c release was stimulated, most of VacA was localized to vacuoles rather than mitochondria. VacA reduced the membrane potential of isolated mitochondria without inducing cytochrome c release, suggesting that it did not act directly to induce cytochrome c release from mitochondria and that in intact cells, VacA-induced cytochrome c release involved apoptosis-related factor(s), such as a proapoptotic Bcl-2 family protein. In agreement, flow cyto-metric analyses using antibodies specific for activated Bax revealed that intracellular Bax was activated by VacA in a concentration- and time-dependent manner. Using active form-specific antibodies, we also observed that the Bcl-2 family protein, Bak, was activated. By confocal microscopy, Bax and Bak were activated in AZ-521 cells in which cyto-chrome c release was induced by VacA. In addition, small interfering RNA-induced silencing of the bax gene resulted in reduction of VacA-stimulated cytochrome c release, consistent with a contribution of VacA-induced Bax activation to cytochrome c release. NH4Cl enhanced both VacA-induced vacuolation and Bax activation, whereas Bax activation was not inhibited by bafilomycin A1, which inhibited vacuolation caused by VacA. These results suggest that VacA acts through different signaling pathways to induce apoptosis via Bax activation, independent of vacuolation.
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Affiliation(s)
- Eiki Yamasaki
- PRESTO, Japan Science and Technology Corporation, Saitama 332-0012, Japan
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42
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Tuccillo C, Cuomo A, Rocco A, Martinelli E, Staibano S, Mascolo M, Gravina AG, Nardone G, Ricci V, Ciardiello F, Del Vecchio Blanco C, Romano M. Vascular endothelial growth factor and neo-angiogenesis in H. pylori gastritis in humans. J Pathol 2005; 207:277-84. [PMID: 16184519 DOI: 10.1002/path.1844] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Host response plays a major role in the pathogenesis of Helicobacter pylori-induced gastroduodenal disease including adenocarcinoma of the distal stomach. Vascular endothelial growth factor (VEGF) is an important modulator of gastric mucosal repair and is overexpressed in gastric cancer. The present study sought to evaluate the expression of VEGF in the gastric mucosa of H. pylori-infected and H. pylori-non-infected dyspeptic patients. Fifteen H. pylori-infected and 15 H. pylori-non-infected dyspeptic patients were studied. Diagnosis of H. pylori infection was based on rapid urease test and histology. VEGF protein expression was assessed by western blotting. VEGF mRNA expression was assessed by RT-PCR. VEGF localization in the gastric mucosa and neo-angiogenesis were determined by immunohistochemistry. VEGF protein and mRNA expression was significantly greater in H. pylori-infected than in non-infected patients. Immunohistochemistry showed that VEGF expression was more intense in the gastric gland compartment of H. pylori-infected mucosa than in the non-infected mucosa. The increase in VEGF expression was associated with a significant increase in neo-angiogenesis as assessed by determination of CD34-positive micro-vessels. H. pylori gastritis is therefore associated with up-regulation of VEGF expression, which parallels the increased formation of blood vessels in the gastric mucosa. It is postulated that increased VEGF expression and neo-angiogenesis may contribute to H. pylori-related gastric carcinogenesis.
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Affiliation(s)
- Concetta Tuccillo
- Dipartimento di Internistica Clinica e Sperimentale-Cattedra di Gastroenterologia, Seconda Università di Napoli, Napoli, Italy
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43
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Ricci V, Chiozzi V, Necchi V, Oldani A, Romano M, Solcia E, Ventura U. Free-soluble and outer membrane vesicle-associated VacA from Helicobacter pylori: Two forms of release, a different activity. Biochem Biophys Res Commun 2005; 337:173-8. [PMID: 16182250 DOI: 10.1016/j.bbrc.2005.09.035] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2005] [Accepted: 09/07/2005] [Indexed: 11/29/2022]
Abstract
Helicobacter pylori releases VacA both as free-soluble and as outer membrane vesicle (OMV)-associated toxin. In this study, we investigated the amount of VacA released in each of the two forms and the role of each form in VacA-induced cell vacuolation in vitro. We found that: (1) free-soluble toxin accounted for about 75% of released VacA, while the remaining 25% was OMV-associated; (2) although OMV-associated VacA caused a statistically significant vacuolation, virtually all the vacuolating activity of a H. pylori broth culture filtrate was due to free-soluble VacA. While it is widely accepted that OMVs may represent an important vehicle for delivering virulence factors to the gastric mucosa, our results suggest that OMV-associated VacA could play a pathobiological role different from that of free-soluble toxin. This conclusion fits with mounting evidence that VacA exerts a large pattern of pathobiological effects among which cell vacuolation might not be the main one.
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Affiliation(s)
- Vittorio Ricci
- Department of Experimental Medicine, Human Physiology Section, Pavia University, Pavia, Italy.
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44
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Gauthier NC, Monzo P, Kaddai V, Doye A, Ricci V, Boquet P. Helicobacter pylori VacA cytotoxin: a probe for a clathrin-independent and Cdc42-dependent pinocytic pathway routed to late endosomes. Mol Biol Cell 2005; 16:4852-66. [PMID: 16055501 PMCID: PMC1237088 DOI: 10.1091/mbc.e05-05-0398] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The vacuolating cytotoxin VacA is a major virulence factor of Helicobacter pylori, a bacterium responsible for gastroduodenal ulcers and cancer. VacA associates with lipid rafts, is endocytosed, and reaches the late endocytic compartment where it induces vacuolation. We have investigated the endocytic and intracellular trafficking pathways used by VacA, in HeLa and gastric AGS cells. We report here that VacA was first bound to plasma-membrane domains localized above F-actin structures that were controlled by the Rac1 GTPase. VacA was subsequently pinocytosed by a clathrin-independent mechanism into cell peripheral early endocytic compartments lacking caveolin 1, the Rab5 effector early endosomes antigen-1 (EEA1) and transferrin. These compartments took up fluid-phase (as evidenced by the accumulation of fluorescent dextran) and glycosylphosphatidylinositol-anchored proteins (GPI-APs). VacA pinocytosis was controlled by Cdc42 and did not require cellular tyrosine kinases, dynamin 2, ADP-ribosylating factor 6, or RhoA GTPase activities. VacA was subsequently routed to EEA1-sorting endosomes and then sorted to late endosomes. During all these different endocytic steps, VacA was continuously associated with detergent resistant membrane domains. From these results we propose that VacA might be a valuable probe to study raft-associated molecules, pinocytosed by a clathrin-independent mechanism, and routed to the degradative compartment.
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Affiliation(s)
- Nils C Gauthier
- INSERM U 627, IFR 50, Faculté de Médecine, 06107 Nice, France
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45
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Hennig EE, Godlewski MM, Butruk E, Ostrowski J. Helicobacter pyloriVacA cytotoxin interacts with fibronectin and alters HeLa cell adhesion and cytoskeletal organization in vitro. ACTA ACUST UNITED AC 2005; 44:143-50. [PMID: 15866208 DOI: 10.1016/j.femsim.2004.10.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2004] [Revised: 10/25/2004] [Accepted: 10/27/2004] [Indexed: 11/17/2022]
Abstract
Helicobacter pylori vacuolating cytotoxin VacA causes multiple effects on epithelial cell function and morphology, but the effects of VacA on signal transduction pathways and the cytoskeleton have not been investigated in detail. In this study, we analyzed the effects of native VacA on HeLa and AGS cell adhesion to fibronectin and laminin under serum-free conditions. Confocal microscopic examination revealed increased number of cells with rounded morphology and inhibition of actin fiber formation, in the presence of VacA. VacA binds to fibronectin in vitro in a dose-dependent manner. This interaction was partly inhibited by a peptide containing an arginine-glycine-aspartic acid motif. The adhesion of HeLa cells to fibronectin, but not to laminin, was decreased in the presence of VacA. Thus, VacA may interact with fibronectin and influence integrin receptor-induced cell signaling and cytoskeleton-dependent cell functions.
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Affiliation(s)
- Ewa E Hennig
- Department of Gastroenterology, Medical Center for Postgraduate Education at the Maria Sklodowska-Curie Memorial Cancer Center, Institute of Oncology, Roentgena 5 str., 02-781 Warsaw, Poland.
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46
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Abstract
Eukaryotic cell viability is largely regulated at the level of mitochondria, with cell death executed by endogenous proteins that act to increase the permeability of the inner and/or outer membranes of these organelles. The gastric pathogen, Helicobacter pylori, can mimic this mechanism by producing the pro-apoptotic toxin, VacA, which was recently demonstrated to (i) localize to mitochondria within epithelial cells, (ii) rapidly transport into mitochondria in vitro, and (iii) induce changes consistent with permeabilization of mitochondrial membranes by a mechanism dependent on cellular entry and toxin membrane channel activity. The targeting of mitochondrial membranes is emerging as a strategy used by pathogenic microbes to control cell viability while circumventing upstream pathways and checkpoints of cell death.
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Affiliation(s)
- Steven R Blanke
- Department of Microbiology and Molecular Genetics, University of Illinois, 302 Burrill Hall, Urbana-Champaign, IL 61801, USA.
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Henderson IR, Navarro-Garcia F, Desvaux M, Fernandez RC, Ala'Aldeen D. Type V protein secretion pathway: the autotransporter story. Microbiol Mol Biol Rev 2004; 68:692-744. [PMID: 15590781 PMCID: PMC539010 DOI: 10.1128/mmbr.68.4.692-744.2004] [Citation(s) in RCA: 635] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Gram-negative bacteria possess an outer membrane layer which constrains uptake and secretion of solutes and polypeptides. To overcome this barrier, bacteria have developed several systems for protein secretion. The type V secretion pathway encompasses the autotransporter proteins, the two-partner secretion system, and the recently described type Vc or AT-2 family of proteins. Since its discovery in the late 1980s, this family of secreted proteins has expanded continuously, due largely to the advent of the genomic age, to become the largest group of secreted proteins in gram-negative bacteria. Several of these proteins play essential roles in the pathogenesis of bacterial infections and have been characterized in detail, demonstrating a diverse array of function including the ability to condense host cell actin and to modulate apoptosis. However, most of the autotransporter proteins remain to be characterized. In light of new discoveries and controversies in this research field, this review considers the autotransporter secretion process in the context of the more general field of bacterial protein translocation and exoprotein function.
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Affiliation(s)
- Ian R Henderson
- Division of Immunity and Infection, University of Birmingham, Birmingham B15 2TT, UK.
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Willhite DC, Blanke SR. Helicobacter pylori vacuolating cytotoxin enters cells, localizes to the mitochondria, and induces mitochondrial membrane permeability changes correlated to toxin channel activity. Cell Microbiol 2004; 6:143-54. [PMID: 14706100 DOI: 10.1046/j.1462-5822.2003.00347.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The Helicobacter pylori vacuolating cytotoxin (VacA) intoxicates mammalian cells resulting in reduction of mitochondrial transmembrane potential (Delta Psi m reduction) and cytochrome c release, two events consistent with the modulation of mitochondrial membrane permeability. We now demonstrate that the entry of VacA into cells and the capacity of VacA to form anion-selective channels are both essential for Delta Psi m reduction and cytochrome c release. Subsequent to cell entry, a substantial fraction of VacA localizes to the mitochondria. Neither Delta Psi m reduction nor cytochrome c release within VacA-intoxicated cells requires cellular caspase activity. Moreover, VacA cellular activity is not sensitive to cyclosporin A, suggesting that VacA does not induce the mitochondrial permeability transition as a mechanism for Delta Psi m reduction and cytochrome c release. Time-course and dose-response studies indicate that Delta Psi m reduction occurs substantially before and at lower concentrations of VacA than cytochrome c release. Collectively, these results support a model that VacA enters mammalian cells, localizes to the mitochondria, and modulates mitochondrial membrane permeability by a mechanism dependent on toxin channel activity ultimately resulting in cytochrome c release. This model represents a novel mechanism for regulation of a mitochondrial-dependent apoptosis pathway by a bacterial toxin.
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Affiliation(s)
- David C Willhite
- Department of Biology and Biochemistry, University of Houston, 369 Science and Research Building II, Houston, TX 77204-5001, USA
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Gauthier NC, Ricci V, Gounon P, Doye A, Tauc M, Poujeol P, Boquet P. Glycosylphosphatidylinositol-anchored Proteins and Actin Cytoskeleton Modulate Chloride Transport by Channels Formed by the Helicobacter pylori Vacuolating Cytotoxin VacA in HeLa Cells. J Biol Chem 2004; 279:9481-9. [PMID: 14676190 DOI: 10.1074/jbc.m312040200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The vacuolating cytotoxin VacA is an important virulence factor of Helicobacter pylori. Removing glycosylphosphatidylinositol-anchored proteins (GPI-Ps) from the cell surface by phosphatidylinositol-phospholipase C or disrupting the cell actin cytoskeleton by cytochalasin D reduced VacA-induced vacuolation of cells. Using the fluorescent dye 6-methoxy-N-ethylquinolinium chloride, an indicator for cytosolic chloride, we have investigated the role of either GPI-Ps or actin cytoskeleton in the activity of the selective anionic channel formed by VacA at the plasma membrane level. Removal of GPI-Ps from HeLa cell surfaces did not impair VacA localization into lipid rafts but strongly reduced VacA channel-mediated cell influx and efflux of chloride. Disruption of the actin cytoskeleton of HeLa cells by cytochalasin D did not affect VacA localization in lipid rafts but blocked VacA cell internalization and inhibited cell vacuolation while increasing the overall chloride transport by the toxin channel at the cell surface. Specific enlargement of Rab7-positive compartments induced by VacA could be mimicked by the weak base chloroquine alone, and the vacuolating activities of either chloroquine alone or VacA were blocked with the same potency by the anion channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoic acid shown to inhibit VacA channel activity. We suggest that formation of functional VacA channels at the cell surface required GPI-Ps and that endocytosis of these channels by an actin-dependent process increases the chloride content of late endosomes that accumulate weak bases, provoking their enlargement by osmotic swelling.
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Affiliation(s)
- Nils C Gauthier
- INSERM U 452, IFR 50, Faculté de Médecine 28 Avenue de Valombrose, 06107 Nice, France
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50
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Abstract
Helicobacter pylori is a global pathogen that causes severe gastrointestinal diseases leading to a significant morbidity and mortality. There is an effective treatment for peptic ulcer disease, however, this is being compromised by an increase in the prevalence of antibiotic resistance. Although alternative rescue regimens have been advocated, the best strategy would be to prevent disease, especially in the case of gastric cancer for which there is still no treatment. One approach is to inhibit the first step in the pathogenic process - adhesion of the organism to the host tissue. Another and probably a better approach is vaccination, but clinical trials have so far been unsuccessful. There is still a large uncertainty in relation to how H. pylori causes disease. Knowledge from genomics, proteomics, and the relationship between polymorphism of the bacterium and the host, as well as the continuing investigation of the role played by important virulence factors in the outcome of the disease, will help both in understanding pathogenesis of disease and in the design of the best vaccine.
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Affiliation(s)
- Rachel O'Mahony
- Centre for Infectious Diseases & International Health, RF&UCL Medical School, UK
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