scholarly journals Effect of Helicobacter pylori on Polymorphonuclear Leukocyte Migration across Polarized T84 Epithelial Cell Monolayers: Role of Vacuolating Toxin VacA and cagPathogenicity Island

2000 ◽  
Vol 68 (9) ◽  
pp. 5225-5233 ◽  
Author(s):  
Véronique Hofman ◽  
Vittorio Ricci ◽  
Antoine Galmiche ◽  
Patrick Brest ◽  
Patrick Auberger ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Polymorphonuclear Leukocyte ◽  
Broth Culture ◽  
Intestinal Cell ◽  
T84 Cells ◽  
Vacuolating Cytotoxin ◽  
Intestinal Cell Line ◽  
H Pylori

ABSTRACT Helicobacter pylori infection can induce polymorphonuclear leukocyte (PMNL) infiltration of the gastric mucosa, which characterizes acute chronic gastritis. The mechanisms underlying this process are poorly documented. The lack of an in vitro model has considerably impaired the study of transepithelial migration of PMNL induced by H. pylori. In the present work, we used confluent polarized monolayers of the human intestinal cell line T84 grown on permeable filters to analyze the epithelial PMNL response induced by broth culture filtrates (BCFs) and bacterial suspensions from different strains of H. pylori. We have evaluated the role of the vacuolating cytotoxin VacA and of the cagpathogenicity island (PAI) of H. pylori in PMNL migration via their effects on T84 epithelial cells. We noted no difference in the rates of PMNL transepithelial migration after epithelial preincubation with bacterial suspensions or with BCFs of VacA-negative or VacA-positive H. pylori strains. In contrast, PMNL transepithelial migration was induced after incubation of the T84 cells with cag PAI-positive and cagE-positiveH. pylori strains. Finally, PMNL migration was correlated with a basolateral secretion of interleukin-8 by T84 cells, thus creating a subepithelial chemotactic gradient for PMNL. These data provide evidence that the vacuolating cytotoxin VacA is not involved in PMNL transepithelial migration and that the cag PAI, with a pivotal role for the cagE gene, provokes a transcellular signal across T84 monolayers, inducing a subepithelial PMNL response.

scholarly journals Heterogeneity in Levels of Vacuolating Cytotoxin Gene (vacA) Transcription among Helicobacter pylori Strains

1998 ◽  
Vol 66 (7) ◽  
pp. 3088-3094 ◽  
Author(s):  
M. H. Forsyth ◽  
J. C. Atherton ◽  
M. J. Blaser ◽  
T. L. Cover
Keyword(s):  
Helicobacter Pylori ◽  
Broth Culture ◽  
Promoter Strength ◽  
Vacuolating Cytotoxin ◽  
H Pylori ◽  
Culture Supernatants ◽  
Different Levels ◽  
Transcriptional Fusions ◽  
Cytotoxin Gene

ABSTRACT Broth culture supernatants from Tox+ Helicobacter pylori strains induce vacuolation of HeLa cells in vitro and contain VacA in concentrations that are higher than those found in supernatants from Tox− H. pyloristrains. To investigate the basis for this phenomenon, we analyzed the transcription of the vacuolating cytotoxin gene (vacA) in eight Tox+ strains (each with a type s1/m1 vacA genotype) and nine Tox− strains (each with a type s2/m2 vacA genotype). Most of the Tox+ and Tox− strains tested used the samevacA transcriptional start point, but Tox+strains yielded significantly stronger primer extension signal intensities than did Tox− strains (mean densitometry values of 15.8 ± 1.9 versus 8.9 ± 1.7, P = 0.0016). Correspondingly, when we introducedvacA::xylE transcriptional fusions into the chromosomes of a Tox+ strain (60190) and a Tox− strain (86-313), the level of XylE activity in 60190vacA::xylE was about 30-fold higher than that in 86-313 vacA::xylE. Sequence analysis and promoter exchange experiments indicated that the different levels of vacA transcription in these two strains cannot be explained solely by a difference in promoter strength. These data indicate that Tox+ and Tox− H. pylori strains typically differ not only in the VacA amino acid sequence but also in the level of vacA transcription.

scholarly journals Colonization and Inflammation Deficiencies in Mongolian Gerbils Infected by Helicobacter pylori Chemotaxis Mutants

2005 ◽  
Vol 73 (3) ◽  
pp. 1820-1827 ◽  
Author(s):  
David J. McGee ◽  
Melanie L. Langford ◽  
Emily L. Watson ◽  
J. Elliot Carter ◽  
Yu-Ting Chen ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Immune Cell ◽  
Response Regulator ◽  
Critical Role ◽  
Mongolian Gerbils ◽  
Wild Type ◽  
In The Wild ◽  
H Pylori

ABSTRACT Helicobacter pylori causes disease in the human stomach and in mouse and gerbil stomach models. Previous results have shown that motility is critical for H. pylori to colonize mice, gerbils, and other animal models. The role of chemotaxis, however, in colonization and disease is less well understood. Two genes in the H. pylori chemotaxis pathway, cheY and tlpB, which encode the chemotaxis response regulator and a methyl-accepting chemoreceptor, respectively, were disrupted. The cheY mutation was complemented with a wild-type copy of cheY inserted into the chromosomal rdxA gene. The cheY mutant lost chemotaxis but retained motility, while all other strains were motile and chemotactic in vitro. These strains were inoculated into gerbils either alone or in combination with the wild-type strain, and colonization and inflammation were assessed. While the cheY mutant completely failed to colonize gerbil stomachs, the tlpB mutant colonized at levels similar to those of the wild type. With the tlpB mutant, there was a substantial decrease in inflammation in the gerbil stomach compared to that with the wild type. Furthermore, there were differences in the numbers of each immune cell in the tlpB-mutant-infected stomach: the ratio of lymphocytes to neutrophils was about 8 to 1 in the wild type but only about 1 to 1 in the mutant. These results suggest that the TlpB chemoreceptor plays an important role in the inflammatory response while the CheY chemotaxis regulator plays a critical role in initial colonization. Chemotaxis mutants may provide new insights into the steps involved in H. pylori pathogenesis.

scholarly journals Essential Role of Ferritin Pfr in Helicobacter pylori Iron Metabolism and Gastric Colonization

2002 ◽  
Vol 70 (7) ◽  
pp. 3923-3929 ◽  
Author(s):  
Barbara Waidner ◽  
Stefan Greiner ◽  
Stefan Odenbreit ◽  
Holger Kavermann ◽  
Jyoti Velayudhan ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Iron Metabolism ◽  
Essential Element ◽  
Iron Starvation ◽  
Iron Storage ◽  
Gastric Colonization ◽  
H Pylori ◽  
Iron Pool

ABSTRACT The reactivity of the essential element iron necessitates a concerted expression of ferritins, which mediate iron storage in a nonreactive state. Here we have further established the role of the Helicobacter pylori ferritin Pfr in iron metabolism and gastric colonization. Iron stored in Pfr enabled H. pylori to multiply under severe iron starvation and protected the bacteria from acid-amplified iron toxicity, as inactivation of the pfr gene restricted growth of H. pylori under these conditions. The lowered total iron content in the pfr mutant, which is probably caused by decreased iron uptake rates, was also reflected by an increased resistance to superoxide stress. Iron induction of Pfr synthesis was clearly diminished in an H. pylori feoB mutant, which lacked high-affinity ferrous iron transport, confirming that Pfr expression is mediated by changes in the cytoplasmic iron pool and not by extracellular iron. This is well in agreement with the recent discovery that iron induces Pfr synthesis by abolishing Fur-mediated repression of pfr transcription, which was further confirmed here by the observation that iron inhibited the in vitro binding of recombinant H. pylori Fur to the pfr promoter region. The functions of H. pylori Pfr in iron metabolism are essential for survival in the gastric mucosa, as the pfr mutant was unable to colonize in a Mongolian gerbil-based animal model. In summary, the pfr phenotypes observed give new insights into prokaryotic ferritin functions and indicate that iron storage and homeostasis are of extraordinary importance for H. pylori to survive in its hostile natural environment.

scholarly journals Role of the rdxA and frxA genes in oxygen-dependent metronidazole resistance of Helicobacter pylori

2004 ◽  
Vol 53 (11) ◽  
pp. 1123-1128 ◽  
Author(s):  
Monique M Gerrits ◽  
Egbert-Jan van der Wouden ◽  
Dorine A Bax ◽  
Anton A van Zwet ◽  
Arnoud HM van Vliet ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Cell Viability ◽  
Protein Synthesis Inhibitor ◽  
Low Oxygen ◽  
Anaerobic Conditions ◽  
Metronidazole Resistance ◽  
Oxygen Conditions ◽  
H Pylori

Almost 50 % of all Helicobacter pylori isolates are resistant to metronidazole, which reduces the efficacy of metronidazole-containing regimens, but does not make them completely ineffective. This discrepancy between in vitro metronidazole resistance and treatment outcome may partially be explained by changes in oxygen pressure in the gastric environment, as metronidazole-resistant (MtzR) H. pylori isolates become metronidazole-susceptible (MtzS) under low oxygen conditions in vitro. In H. pylori the rdxA and frxA genes encode reductases which are required for the activation of metronidazole, and inactivation of these genes results in metronidazole resistance. Here the role of inactivating mutations in these genes on the reversibility of metronidazole resistance under low oxygen conditions is established. Clinical H. pylori isolates containing mutations resulting in a truncated RdxA and/or FrxA protein were selected and incubated under anaerobic conditions, and the effect of these conditions on the MICs of metronidazole, amoxycillin, clarithromycin and tetracycline, and cell viability were determined. While anaerobiosis had no effect on amoxycillin, clarithromycin and tetracycline resistance, all isolates lost their metronidazole resistance when cultured under anaerobic conditions. This loss of metronidazole resistance also occurred in the presence of the protein synthesis inhibitor chloramphenicol. Thus, factor(s) that activate metronidazole under low oxygen tension are not specifically induced by low oxygen conditions, but are already present under microaerophilic conditions. As there were no significant differences in cell viability between the clinical isolates, it is likely that neither the rdxA nor the frxA gene participates in the reversibility of metronidazole resistance.

scholarly journals Helicobacter pylori Alters Exogenous Antigen Absorption and Processing in a Digestive Tract Epithelial Cell Line Model

1998 ◽  
Vol 66 (12) ◽  
pp. 5785-5791 ◽  
Author(s):  
Tamara Matysiak-Budnik ◽  
Kathleen Terpend ◽  
Sophie Alain ◽  
Marie-José Sanson le Pors ◽  
Jehan-Francois Desjeux ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Intercellular Junctions ◽  
Paracellular Pathway ◽  
Broth Culture ◽  
Epithelial Cell Line ◽  
Epithelial Barrier Function ◽  
Ussing Chambers ◽  
H Pylori ◽  
Culture Supernatants

ABSTRACT To study the influence of Helicobacter pylori on epithelial barrier function, bacteria, bacterial sonicates, or broth culture supernatants were incubated for 24 h with HT29-19A intestinal cells grown as monolayers. Subsequently, the monolayers were mounted in Ussing chambers, and electrical resistance (R), fluxes of 22Na (JNa) and14C-mannitol (JMan) (markers of the paracellular pathway), and fluxes of horseradish peroxidase (HRP) in total (J3H-HRP), intact (JHRPi), and degraded forms were measured. H. pylori did not induce any modification of the paracellular pathway (R = 148 ± 10 versus 174 ± 16 Ω · cm2; JNa = 4.16 ± 0.44 versus 3.51 ± 0.41 μEq/h · cm2; JMan = 0.081 ± 0.01 versus 0.058 ± 0.009 μmol/h · cm2), nor did it modify J3H-HRP (2,201 ± 255 versus 2,110 ± 210 ng/h · cm2 forH. pylori-infected and control cells, respectively). However, in the presence of H. pylori, we observed a significant increase in JHRPi (520 ± 146 versus 171 ± 88 ng/h · cm2). This effect was not dependent of thecag status of the strain and was not reproduced by the sonicates or the culture supernatants. It was related to the presence of urease, since a urease-negative mutant of H. pylori did not induce this effect. Ammonia and bafilomycin A1, two agents known to increase the endolysosomal pH, reproduced the increase in JHRPi. In conclusion, H. pylori does not affect directly the integrity of intercellular junctions of epithelial cells in vitro, but it increases the passage of intact HRP, probably by inhibition of the intralysosomal degradation due to the release of ammonia. The increased transport of intact macromolecules may contribute to the induction and maintenance of gastric inflammation by H. pylori.

The Role of E-cadherin in Helicobacter pylori-Related Gastric Diseases

2019 ◽  
Vol 20 (1) ◽  
pp. 23-28
Author(s):  
Yunzhan Zhang ◽  
Danyan Li ◽  
Yunkai Dai ◽  
Ruliu Li ◽  
Yong Gao ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Gastric Mucosa ◽  
Precancerous Lesions ◽  
Research Literature ◽  
Gastric Diseases ◽  
H Pylori ◽  
The Relationship ◽  
E Cadherin

Background: Helicobacter pylori (H. pylori)-related gastric diseases are a series of gastric mucosal disorders associated with H. pylori infection. Gastric cancer (GC) is widely believed to evolve from gastritis and gastric ulcer. As an important adhesion molecule of epithelial cells, E-cadherin plays a key role in the development of gastric diseases. In this review, we aim to seek the characteristic of E-cadherin expression at different stages of gastric diseases. Methods: We searched plenty of databases for research literature about E-cadherin expression in H. pylori-related gastric diseases, and reviewed the relationship of E-cadherin and H. pylori, and the role of E-cadherin at different stages of gastric diseases. Results: H. pylori was shown to decrease E-cadherin expression by various ways in vitro, while most of clinical studies have not found the relationship between H. pylori and E-cadherin expression. It is defined that poor outcome of GC is related to loss expression of E-cadherin, but it is still unclear when qualitative change of E-cadherin expression in gastric mucosa emerges. Conclusion: Expression level of E-cadherin in gastric cells may be a consequence of injury factors and body’s selfrepairing ability. More studies on E-cadherin expression in gastric mucosa with precancerous lesions need to be performed, which may be potential and useful for early detection, prevention and treatment of GC.

scholarly journals Paired cysteine residues are required for high levels of the Helicobacter pylori autotransporter VacA

Microbiology ◽  
2006 ◽  
Vol 152 (5) ◽  
pp. 1319-1325 ◽  
Author(s):  
Darren P. Letley ◽  
Joanne L. Rhead ◽  
Keith Bishop ◽  
John C. Atherton
Keyword(s):  
Helicobacter Pylori ◽  
Bond Formation ◽  
Cysteine Residues ◽  
Single Pair ◽  
Passenger Domain ◽  
Vacuolating Cytotoxin ◽  
C Terminus ◽  
Disulphide Bond Formation ◽  
H Pylori

The Helicobacter pylori vacuolating cytotoxin VacA shares homology in its C-terminal domain with many autotransporter proteins, suggesting a similar mechanism of secretion. Like most autotransporters, VacA contains a single pair of cysteine residues located near the C-terminus of the passenger domain. This study aimed to investigate the role of these conserved cysteine residues. This involved changing each cysteine in the VacA passenger domain to serine, quantifying the effect on VacA levels and assessing toxin activity in H. pylori. It was shown that both cysteine residues were required for high VacA levels, although mutation of each cysteine reduced toxin amounts to differing extents, implying that their importance was not simply for intramolecular disulphide bond formation. Although less VacA was observed for the cysteine mutants, vacuolating activity was detected, showing that the cysteines were not required for VacA function.

scholarly journals Effect of Cold Starvation, Acid Stress, and Nutrients on Metabolic Activity of Helicobacter pylori

2002 ◽  
Vol 68 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Hans-Olof Nilsson ◽  
Jens Blom ◽  
Waleed Abu Al-Soud ◽  
Åsa Ljungh ◽  
Leif P. Andersen ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Reverse Transcription ◽  
Disease Transmission ◽  
Broth Culture ◽  
Total Rna ◽  
Reverse Transcription Pcr ◽  
Metabolic Activities ◽  
H Pylori ◽  
Polyphosphate Granules

ABSTRACT Helicobacter pylori can transform, in vivo as well as in vitro, from dividing spiral-shaped forms into nonculturable coccoids, with intermediate forms called U forms. The importance of nonculturable coccoid forms of H. pylori in disease transmission and antibiotic treatment failures is unclear. Metabolic activities of actively growing as well as nonculturable H. pylori were investigated by comparing the concentrations of cellular ATP and total RNA, gene expression, presence of cytoplasmic polyphosphate granules and iron inclusions, and cellular morphology during extended broth culture and nutritional cold starvation. In addition, the effect of exposing broth-cultured or cold-starved cells to a nutrient-rich or acidic environment on the metabolic activities was investigated. ATP was detectable up to 14 days and for at least 25 days after transformation from the spiral form to the coccoid form or U form in broth-cultured and cold-starved cells, respectively. mRNAs of VacA, a 26-kDa protein, and urease A were detected by using reverse transcription-PCR in cells cultured for 2 months in broth or cold starved for at least 28 months. The ATP concentration was not affected during exposure to fresh or acidified broth, while 4- to 12-h exposures of nonculturable cells to lysed human erythrocytes increased cellular ATP 12- to 150-fold. Incubation of nonculturable cold-starved cells with an erythrocyte lysate increased total RNA expression and ureA mRNA transcription as measured by quantitative real-time reverse transcription-PCR. Furthermore, the number of structurally intact starved coccoids containing polyphosphate granules increased almost fourfold (P = 0.0022) under the same conditions. In conclusion, a specific environmental stimulus can induce ATP, polyphosphate, and RNA metabolism in nonculturable H. pylori, indicating viability of such morphological forms.

scholarly journals Helicobacter pylori Stimulates Dendritic Cells To Induce Interleukin-17 Expression from CD4+ T Lymphocytes

2009 ◽  
Vol 78 (2) ◽  
pp. 845-853 ◽  
Author(s):  
Wafa Khamri ◽  
Marjorie M. Walker ◽  
Peter Clark ◽  
John C. Atherton ◽  
Mark R. Thursz ◽  
...  
Keyword(s):  
T Cells ◽  
Helicobacter Pylori ◽  
Dendritic Cells ◽  
Virulence Factors ◽  
Human Monocyte ◽  
Interleukin 17 ◽  
Th17 Response ◽  
H Pylori

ABSTRACT Helicobacter pylori is a human gastroduodenal pathogen that leads to active chronic inflammation characterized by T-cell responses biased toward a Th1 phenotype. It has been accepted that H. pylori infection induces a Th17 response. At mucosal sites, dendritic cells (DCs) have the capacity to induce effector T cells. Here, we evaluate the role of DCs in the H. pylori-induced interleukin-17 (IL-17) response. Immunohistochemistry and immunofluorescence were performed on human gastric mucosal biopsy samples and showed that myeloid DCs in H. pylori-infected patients colocalized with IL-23- and that IL-17-producing lymphocytes were present in H. pylori-infected antral biopsy samples. In parallel, human monocyte-derived DCs stimulated in vitro with live H. pylori cells produced significant levels of IL-23 in the absence of IL-12 release. The subsequent incubation of H. pylori-infected DCs with autologous CD4+ T cells led to gamma interferon (IFN-γ) and IL-17 expression. The inhibition of IL-1 and, to a lesser extent, IL-23 inhibited IL-17 production by T cells. Finally, isogenic H. pylori mutant strains not expressing major virulence factors were less effective in inducing IL-1 and IL-23 release by DCs and IL-17 release by T cells than parental strains. Altogether, we can conclude that DCs are potent inducers of IL-23/IL-17 expression following H. pylori stimulation. IL-1/IL-23 as well as H. pylori virulence factors seem to play an important role in mediating this response.

scholarly journals NF-κB Activation during Acute Helicobacter pylori Infection in Mice

2007 ◽  
Vol 76 (2) ◽  
pp. 551-561 ◽  
Author(s):  
Richard L. Ferrero ◽  
Patrick Avé ◽  
Delphine Ndiaye ◽  
Jean-Christophe Bambou ◽  
Michel R. Huerre ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Transgenic Mice ◽  
Nuclear Factor Κb ◽  
Helicobacter Felis ◽  
Cell Responses ◽  
Mucosal Cells ◽  
H Pylori ◽  
First Time

ABSTRACT Nuclear factor κB (NF-κB) plays a key regulatory role in host cell responses to Helicobacter pylori infection in humans. Although mice are routinely used as a model to study H. pylori pathogenesis, the role of NF-κB in murine cell responses to helicobacters has not been studied in detail. We thus investigated the abilities of different Helicobacter isolates to induce NF-κB-dependent responses in murine gastric epithelial cells (GECs) and in transgenic mice harboring an NF-κB-responsive lacZ reporter gene. H. pylori and Helicobacter felis strains up-regulated the synthesis in mouse GECs of the NF-κB-dependent chemokines KC (CXCL1) and MIP-2 (CXCL2). These responses were cag pathogenicity island (cagPAI) independent and could be abolished by pretreatment with a pharmacological inhibitor of NF-κB. Consistent with the in vitro data, experimental Helicobacter infection of transgenic mice resulted in increased numbers of GECs with nuclear β-galactosidase activity, which is indicative of specific NF-κB activation. The numbers of β-galactosidase-positive cells in mice were significantly increased at day 1 postinoculation with wild-type H. pylori strains harboring or not harboring a functional cagPAI, compared to naive animals (P = 0.007 and P = 0.04, respectively). Strikingly, however, no differences were observed in the levels of gastric NF-κB activation at day 1 postinoculation with H. felis or at day 30 or 135 postinoculation with H. pylori. This work demonstrates for the first time the induction of NF-κB activation within gastric mucosal cells during acute H. pylori infection. Furthermore, the data suggest that helicobacters may be able to regulate NF-κB signaling during chronic infection.

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