scholarly journals Pyridodiazepine Amines Are Selective Therapeutic Agents for Helicobacter pylori by Suppressing Growth through Inhibition of Glutamate Racemase but Are Predicted To Require Continuous Elevated Levels in Plasma To Achieve Clinical Efficacy

2015 ◽  
Vol 59 (4) ◽  
pp. 2337-2342 ◽  
Author(s):  
Boudewijn L. M. de Jonge ◽  
Amy Kutschke ◽  
Joseph V. Newman ◽  
Michael T. Rooney ◽  
Wei Yang ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Therapeutic Agents ◽  
Infection Model ◽  
Content Type ◽  
Peptidoglycan Biosynthesis ◽  
Glutamate Racemase ◽  
Mouse Infection Model ◽  
Exposure Levels ◽  
H Pylori ◽  
Extended Exposure

ABSTRACTA pyridodiazepine amine inhibitor ofHelicobacter pyloriglutamate racemase (MurI) was characterized. The compound was selectively active againstH. pylori, and growth suppression was shown to be mediated through the inhibition of MurI by several methods. In killing kinetics experiments, the compound showed concentration-independent activity, with about a 2-log loss of viability in 24 h. A demonstration of efficacy in a mouse infection model was attempted but not achieved, and this was attributed to the failure to attain extended exposure levels above the MIC for >95% of the time. This index and magnitude were derived from pharmacokinetic-pharmacodynamic (PK-PD) studies with amoxicillin, another inhibitor of peptidoglycan biosynthesis that showed slow killing kinetics similar to those of the pyridodiazepine amines. These studies indicate that MurI and other enzymes involved in peptidoglycan biosynthesis may be less desirable targets for monotherapy directed againstH. pyloriif once-a-day dosing is required.

scholarly journals Peptidoglycan Deacetylation in Helicobacter pylori Contributes to Bacterial Survival by Mitigating Host Immune Responses

2010 ◽  
Vol 78 (11) ◽  
pp. 4660-4666 ◽  
Author(s):  
Ge Wang ◽  
Susan E. Maier ◽  
Leja F. Lo ◽  
George Maier ◽  
Shruti Dosi ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Helicobacter Pylori ◽  
Immune Responses ◽  
Bacterial Load ◽  
Host Cells ◽  
Infection Model ◽  
Wild Type ◽  
Mouse Infection Model ◽  
Mouse Infection ◽  
H Pylori

ABSTRACT An oxidative stress-induced enzyme, peptidoglycan deacetylase (PgdA), in the human gastric pathogen Helicobacter pylori was previously identified and characterized. In this study, we constructed H. pylori pgdA mutants in two mouse-adapted strains, X47 and B128, to investigate the role of PgdA in vivo (to determine the mutants’ abilities to colonize mice and to induce an immune response). H. pylori pgdA mutant cells showed increased sensitivity to lysozyme compared to the sensitivities of the parent strains. We demonstrated that the expression of PgdA was significantly induced (3.5-fold) when H. pylori cells were in contact with macrophages, similar to the effect observed with oxidative stress as the environmental inducer. Using a mouse infection model, we first examined the mouse colonization ability of an H. pylori pgdA mutant in X47, a strain deficient in the major pathway (cag pathogenicity island [PAI] encoded) for delivery of peptidoglycan into host cells. No animal colonization difference between the wild type and the mutant was observed 3 weeks after inoculation. However, the pgdA mutant showed a significantly attenuated ability to colonize mouse stomachs (9-fold-lower bacterial load) at 9 weeks postinoculation. With the cag PAI-positive strain B128, a significant colonization difference between the wild type and the pgdA mutant was observed at 3 weeks postinoculation (1.32 × 104 versus 1.85 × 103 CFU/gram of stomach). To monitor the immune responses elicited by H. pylori in the mouse infection model, we determined the concentrations of cytokines present in mouse sera. In the mice infected with the pgdA mutant strain, we observed a highly significant increase in the level of MIP-2. In addition, significant increases in interleukin-10 and tumor necrosis factor alpha in the pgdA mutant-infected mice compared to the levels in the wild-type H. pylori-infected mice were also observed. These results indicated that H. pylori peptidoglycan deacetylation is an important mechanism for mitigating host immune detection; this likely contributes to pathogen persistence.

scholarly journals Anti-Helicobacter pylori Potential of Artemisinin and Its Derivatives

2012 ◽  
Vol 56 (9) ◽  
pp. 4594-4607 ◽  
Author(s):  
Suchandra Goswami ◽  
Rajendra S. Bhakuni ◽  
Annalakshmi Chinniah ◽  
Anirban Pal ◽  
Sudip K. Kar ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Artemisia Annua ◽  
Infection Model ◽  
Strong Activity ◽  
Content Type ◽  
Content Development ◽  
Candidate Drug ◽  
Resistant Strains ◽  
H Pylori

ABSTRACTThe antimalarial drug artemisinin fromArtemisia annuademonstrated remarkably strong activity againstHelicobacter pylori, the pathogen responsible for peptic ulcer diseases. In an effort to develop a novel antimicrobial chemotherapeutic agent containing such a sesquiterpene lactone endoperoxide, a series of analogues (2 natural and 15 semisynthetic molecules), including eight newly synthesized compounds, were investigated against clinical and standard strains ofH. pylori. The antimicrobial spectrum against 10H. pyloristrains and a few other bacterial and fungal strains indicated specificity against the ulcer causing organism. Of five promising molecules, a newly synthesized ether derivative β-artecyclopropylmether was found to be the most potent compound, which exhibited MIC range, MIC90, and minimum bactericidal concentration range values of 0.25 to 1.0 μg/ml, 1.0 μg/ml, and 1 to 16 μg/ml, respectively, against both resistant and sensitive strains ofH. pylori. The molecule demonstrated strong bactericidal kinetics with extensive morphological degeneration, retained functional efficacy at stomach acidic pH unlike clarithromycin, did not elicit drug resistance unlike metronidazole, and imparted sensitivity to resistant strains. It is not cytotoxic and exhibitsin vivopotentiality to reduce theH. pyloriburden in a chronic infection model. Thus, β-artecyclopropylmether could be a lead candidate for anti-H. pyloritherapeutics. Since the recurrence of gastroduodenal ulcers is believed to be mainly due to antibiotic resistance of the commensal organismH. pylori, development of a candidate drug from this finding is warranted.

scholarly journals Pyrazolopyrimidinediones Are Selective Agents for Helicobacter pylori That Suppress Growth through Inhibition of Glutamate Racemase (MurI)

2009 ◽  
Vol 53 (8) ◽  
pp. 3331-3336 ◽  
Author(s):  
B. L. M. de Jonge ◽  
A. Kutschke ◽  
M. Uria-Nickelsen ◽  
H. D. Kamp ◽  
S. D. Mills
Keyword(s):  
Helicobacter Pylori ◽  
Peptidoglycan Biosynthesis ◽  
Glutamate Racemase ◽  
Selective Agents ◽  
Essential Enzyme ◽  
H Pylori ◽  
Selective Therapy ◽  
High Degree

ABSTRACT Pyrazolopyrimidinediones are a novel series of compounds that inhibit growth of Helicobacter pylori specifically. Using a variety of methods, advanced analogues were shown to suppress the growth of H. pylori through the inhibition of glutamate racemase, an essential enzyme in peptidoglycan biosynthesis. The high degree of selectivity of the series for H. pylori makes these compounds attractive candidates for novel H. pylori-selective therapy.

scholarly journals Identification of Helicobacter pylori Genes That Contribute to Stomach Colonization

2006 ◽  
Vol 75 (2) ◽  
pp. 1005-1016 ◽  
Author(s):  
David N. Baldwin ◽  
Benjamin Shepherd ◽  
Petra Kraemer ◽  
Michael K. Hall ◽  
Laura K. Sycuro ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Pathogenic Bacteria ◽  
Null Alleles ◽  
Infection Model ◽  
Genetic Loci ◽  
Pathogenic Potential ◽  
Mouse Infection Model ◽  
Urease Enzyme ◽  
Transposon Mutants ◽  
H Pylori

ABSTRACT Chronic infection of the human stomach by Helicobacter pylori leads to a variety of pathological sequelae, including peptic ulcer and gastric cancer, resulting in significant human morbidity and mortality. Several genes have been implicated in disease related to H. pylori infection, including the vacuolating cytotoxin and the cag pathogenicity island. Other factors important for the establishment and maintenance of infection include urease enzyme production, motility, iron uptake, and stress response. We utilized a C57BL/6 mouse infection model to query a collection of 2,400 transposon mutants in two different bacterial strain backgrounds for H. pylori genetic loci contributing to colonization of the stomach. Microarray-based tracking of transposon mutants allowed us to monitor the behavior of transposon insertions in 758 different gene loci. Of the loci measured, 223 (29%) had a predicted colonization defect. These included previously described H. pylori virulence genes, genes implicated in virulence in other pathogenic bacteria, and 81 hypothetical proteins. We have retested 10 previously uncharacterized candidate colonization gene loci by making independent null alleles and have confirmed their colonization phenotypes by using competition experiments and by determining the dose required for 50% infection. Of the genetic loci retested, 60% have strain-specific colonization defects, while 40% have phenotypes in both strain backgrounds for infection, highlighting the profound effect of H. pylori strain variation on the pathogenic potential of this organism.

scholarly journals A RecB-Like Helicase in Helicobacter pylori Is Important for DNA Repair and Host Colonization

2008 ◽  
Vol 77 (1) ◽  
pp. 286-291 ◽  
Author(s):  
Ge Wang ◽  
Robert J. Maier
Keyword(s):  
Dna Damage ◽  
Helicobacter Pylori ◽  
Mutant Strain ◽  
Dna Recombination ◽  
Acid Stress ◽  
Infection Model ◽  
Mouse Infection Model ◽  
Genes Encoding ◽  
H Pylori ◽  
High Degree

ABSTRACT The human gastric pathogen Helicobacter pylori encounters frequent oxidative and acid stress in its specific niche, and this causes bacterial DNA damage. H. pylori exhibits a very high degree of DNA recombination, which is required for repairing both DNA double-stranded (ds) breaks and blocked replication forks. Nevertheless, few genes encoding components of DNA recombinational repair processes have been identified in H. pylori. An H. pylori mutant defective in a putative helicase gene (HP1553) was constructed and characterized herein. The HP1553 mutant strain was much more sensitive to mitomycin C than the WT strain, indicating that HP1553 is required for repair of DNA ds breaks. Disruption of HP1553 resulted in a significant decrease in the DNA recombination frequency, suggesting that HP1553 is involved in DNA recombination processes, probably functioning as a RecB-like helicase. HP1553 was shown to be important for H. pylori protection against oxidative stress-induced DNA damage, as the exposure of the HP1553 mutant cells to air for 6 h caused significant fragmentation of genomic DNA and led to cell death. In a mouse infection model, the HP1553 mutant strain displayed a greatly reduced ability to colonize the host stomachs, indicating that HP1553 plays a significant role in H. pylori survival/colonization in the host.

scholarly journals Two-Component Systems of Helicobacter pylori Contribute to Virulence in a Mouse Infection Model

2003 ◽  
Vol 71 (9) ◽  
pp. 5381-5385 ◽  
Author(s):  
Klaus Panthel ◽  
Patricia Dietz ◽  
Rainer Haas ◽  
Dagmar Beier
Keyword(s):  
Helicobacter Pylori ◽  
Transcriptional Control ◽  
Response Regulator ◽  
Infection Model ◽  
Histidine Kinases ◽  
Reading Frame ◽  
Mouse Infection Model ◽  
Regulatory Systems ◽  
Two Component ◽  
H Pylori

ABSTRACT Helicobacter pylori encodes three histidine kinases and five response regulators belonging to the family of two-component regulatory systems which are involved in transcriptional control. Here we demonstrate that isogenic mutants of H. pylori P76 with deletions of the response regulator open reading frame (ORF) HP1365 and ORFs HP244, HP165, and HP1364 encoding histidine kinases are unable to colonize the stomachs of BALB/c mice, suggesting an essential role of these systems in the regulation of important virulence properties of H. pylori. Furthermore, we demonstrate that the genes under the control of the PHP1408 and PHP119 promoters which are regulated by the two-component system HP166-HP165 are not essential for single mutant colonization of mice but are required under competitive colonization conditions.

scholarly journals Role of Energy Sensor TlpD of Helicobacter pylori in Gerbil Colonization and Genome Analyses after Adaptation in the Gerbil

2013 ◽  
Vol 81 (10) ◽  
pp. 3534-3551 ◽  
Author(s):  
Wiebke Behrens ◽  
Tobias Schweinitzer ◽  
Joena Bal ◽  
Martina Dorsch ◽  
André Bleich ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Human Isolate ◽  
Infection Model ◽  
Energy Yield ◽  
Content Type ◽  
Full Characterization ◽  
H Pylori ◽  
The Impact

ABSTRACTHelicobacter pylorimaintains colonization in its human host using a limited set of taxis sensors. TlpD is a proposed energy taxis sensor ofH. pyloriand dominant under environmental conditions of low bacterial energy yield. We studied the impact ofH. pyloriTlpD on colonizationin vivousing a gerbil infection model which closely mimics the gastric physiology of humans. A gerbil-adaptedH. pyloristrain, HP87 P7, showed energy-dependent behavior, while its isogenictlpDmutant lost it. A TlpD-complemented strain regained the wild-type phenotype. Infection of gerbils with the complemented strain demonstrated that TlpD is important for persistent infection in the antrum and corpus and suggested a role of TlpD in horizontal navigation and persistent corpus colonization. As a part of the full characterization of the model and to gain insight into the genetic basis ofH. pyloriadaptation to the gerbil, we determined the complete genome sequences of the gerbil-adapted strain HP87 P7, two HP87 P7tlpDmutants before and after gerbil passage, and the original human isolate, HP87. The integrity of the genome, including that of a functionalcagpathogenicity island, was maintained after gerbil adaptation. Genetic and phenotypic differences between the strains were observed. Major differences between the gerbil-adapted strain and the human isolate emerged, including evidence of recent recombination. Passage of thetlpDmutant through the gerbil selected for gain-of-function variation in a fucosyltransferase gene,futC(HP0093). In conclusion, a gerbil-adaptedH. pyloristrain with a stable genome has helped to establish that TlpD has important functions for persistent colonization in the stomach.

scholarly journals Agent-Based Modeling Demonstrates How Local Chemotactic Behavior Can Shape Biofilm Architecture

mSphere ◽  
2019 ◽  
Vol 4 (3) ◽  
Author(s):  
Emily G. Sweeney ◽  
Andrew Nishida ◽  
Alexandra Weston ◽  
Maria S. Bañuelos ◽  
Kristin Potter ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Three Dimensional ◽  
Structural Features ◽  
Agent Based Modeling ◽  
Emergent Properties ◽  
Cellular Interactions ◽  
Biofilm Growth ◽  
Content Type ◽  
Agent Based ◽  
H Pylori

ABSTRACTBacteria are often found living in aggregated multicellular communities known as biofilms. Biofilms are three-dimensional structures that confer distinct physical and biological properties to the collective of cells living within them. We used agent-based modeling to explore whether local cellular interactions were sufficient to give rise to global structural features of biofilms. Specifically, we asked whether chemorepulsion from a self-produced quorum-sensing molecule, autoinducer-2 (AI-2), was sufficient to recapitulate biofilm growth and cellular organization observed for biofilms ofHelicobacter pylori, a common bacterial resident of human stomachs. To carry out this modeling, we modified an existing platform, Individual-based Dynamics of Microbial Communities Simulator (iDynoMiCS), to incorporate three-dimensional chemotaxis, planktonic cells that could join or leave the biofilm structure, and cellular production of AI-2. We simulated biofilm growth of previously characterizedH. pyloristrains with various AI-2 production and sensing capacities. Using biologically plausible parameters, we were able to recapitulate both the variation in biofilm mass and cellular distributions observed with these strains. Specifically, the strains that were competent to chemotax away from AI-2 produced smaller and more heterogeneously spaced biofilms, whereas the AI-2 chemotaxis-defective strains produced larger and more homogeneously spaced biofilms. The model also provided new insights into the cellular demographics contributing to the biofilm patterning of each strain. Our analysis supports the idea that cellular interactions at small spatial and temporal scales are sufficient to give rise to larger-scale emergent properties of biofilms.IMPORTANCEMost bacteria exist in aggregated, three-dimensional structures called biofilms. Although biofilms play important ecological roles in natural and engineered settings, they can also pose societal problems, for example, when they grow in plumbing systems or on medical implants. Understanding the processes that promote the growth and disassembly of biofilms could lead to better strategies to manage these structures. We had previously shown thatHelicobacter pyloribacteria are repulsed by high concentrations of a self-produced molecule, AI-2, and thatH. pylorimutants deficient in AI-2 sensing form larger and more homogeneously spaced biofilms. Here, we used computer simulations of biofilm formation to show that localH. pyloribehavior of repulsion from high AI-2 could explain the overall architecture ofH. pyloribiofilms. Our findings demonstrate that it is possible to change global biofilm organization by manipulating local cell behaviors, which suggests that simple strategies targeting cells at local scales could be useful for controlling biofilms in industrial and medical settings.

scholarly journals A Novel Line Immunoassay Based on Recombinant Virulence Factors Enables Highly Specific and Sensitive Serologic Diagnosis of Helicobacter pylori Infection

2013 ◽  
Vol 20 (11) ◽  
pp. 1703-1710 ◽  
Author(s):  
Luca Formichella ◽  
Laura Romberg ◽  
Christian Bolz ◽  
Michael Vieth ◽  
Michael Geppert ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Immune Responses ◽  
Virulence Factors ◽  
Gastrointestinal Disease ◽  
Individual Risk ◽  
Enzyme Linked Immunosorbent Assay ◽  
Type I ◽  
Serologic Test ◽  
Content Type ◽  
H Pylori

ABSTRACTHelicobacter pyloricolonizes half of the world's population, and infection can lead to ulcers, gastric cancer, and mucosa-associated lymphoid tissue (MALT) lymphoma. Serology is the only test applicable for large-scale, population-based screening, but current tests are hampered by a lack of sensitivity and/or specificity. Also, no serologic test allows the differentiation of type I and type II strains, which is important for predicting the clinical outcome.H. pylorivirulence factors have been associated with disease, but direct assessment of virulence factors requires invasive methods to obtain gastric biopsy specimens. Our work aimed at the development of a highly sensitive and specific, noninvasive serologic test to detect immune responses to importantH. pylorivirulence factors. This line immunoassay system (recomLine) is based on recombinant proteins. For this assay, six highly immunogenic virulence factors (CagA, VacA, GroEL, gGT, HcpC, and UreA) were expressed inEscherichia coli, purified, and immobilized to nitrocellulose membranes to detect serological immune responses in patient's sera. For the validation of the line assay, a cohort of 500 patients was screened, of which 290 (58.0%) wereH. pylorinegative and 210 (42.0%) were positive by histology. The assay showed sensitivity and specificity of 97.6% and 96.2%, respectively, compared to histology. In direct comparison to lysate blotting and enzyme-linked immunosorbent assay (ELISA), therecomLine assay had increased discriminatory power. For the assessment of individual risk for gastrointestinal disease, the test must be validated in a larger and defined patient cohort. Taking the data together, therecomLine assay provides a valuable tool for the diagnosis ofH. pyloriinfection.

scholarly journals Basal Body Structures Differentially Affect Transcription of RpoN- and FliA-Dependent Flagellar Genes in Helicobacter pylori

2015 ◽  
Vol 197 (11) ◽  
pp. 1921-1930 ◽  
Author(s):  
Jennifer Tsang ◽  
Timothy R. Hoover
Keyword(s):  
Helicobacter Pylori ◽  
Basal Body ◽  
Protein Interactions ◽  
Transcript Levels ◽  
Content Type ◽  
Genes Encoding ◽  
H Pylori ◽  
Flagellar Biogenesis ◽  
Flagellar Genes

ABSTRACTFlagellar biogenesis inHelicobacter pyloriis regulated by a transcriptional hierarchy governed by three sigma factors, RpoD (σ80), RpoN (σ54), and FliA (σ28), that temporally coordinates gene expression with the assembly of the flagellum. Previous studies showed that loss of flagellar protein export apparatus components inhibits transcription of flagellar genes. The FlgS/FlgR two-component system activates transcription of RpoN-dependent genes though an unknown mechanism. To understand better the extent to which flagellar gene regulation is coupled to flagellar assembly, we disrupted flagellar biogenesis at various points and determined how these mutations affected transcription of RpoN-dependent (flaBandflgE) and FliA-dependent (flaA) genes. The MS ring (encoded byfliF) is one of the earliest flagellar structures assembled. Deletion offliFresulted in the elimination of RpoN-dependent transcripts and an ∼4-fold decrease inflaAtranscript levels. FliH is a cytoplasmic protein that functions with the C ring protein FliN to shuttle substrates to the export apparatus. Deletions offliHand genes encoding C ring components (fliMandfliY) decreased transcript levels offlaBandflgEbut had little or no effect on transcript levels offlaA. Transcript levels offlaBandflgEwere elevated in mutants where genes encoding rod proteins (fliEandflgBC) were deleted, while transcript levels offlaAwas reduced ∼2-fold in both mutants. We propose that FlgS responds to an assembly checkpoint associated with the export apparatus and that FliH and one or more C ring component assist FlgS in engaging this flagellar structure.IMPORTANCEThe mechanisms used by bacteria to couple transcription of flagellar genes with assembly of the flagellum are poorly understood. The results from this study identified components of theH. pyloriflagellar basal body that either positively or negatively affect expression of RpoN-dependent flagellar genes. Some of these basal body proteins may interact directly with regulatory proteins that control transcription of theH. pyloriRpoN regulon, a hypothesis that can be tested by examining protein-protein interactionsin vitro.

Sign in / Sign up

Export Citation Format

Share Document