scholarly journals Subtractive Proteomics Analysis Revealed Lipid A-4’phosphatase (lpxF) as a Potential Candidate for Epitope-based Vaccine Design Against Helicobacter pylori Infection

2021 ◽  
Author(s):  
Pavan Gollapalli ◽  
Tamizh Selvan Gnanasekaran ◽  
Aditya SJ Rao ◽  
Manjunatha Hanumanthappa ◽  
Koigoora Srika ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Drug Targets ◽  
Lipid A ◽  
Cytotoxic T Lymphocyte ◽  
Therapeutic Drug ◽  
Potential Candidate ◽  
Proteomics Analysis ◽  
Subtractive Proteomics ◽  
H Pylori ◽  
Docking Energy

Abstract Amidst the surge in the prevalence of resistant H. pylori infections, WHO in 2017 has given a high priority to clarithromycin-resistant H. pylori for research and to develop new antibacterial agents. In this study, the Helicobacter pylori 26695 strain was investigated with extensive computational biology applications to identify novel therapeutic drug targets or vaccine candidates. During the proteomic functional annotation of an organism, it is crucial to determine the function of proteins. The pathogen-specific pathways were found to include only twelve proteins, paving the way further to determine drug or vaccine targets. Lipoprotein A-4’-phosphatase (LpxF) was found to be a novel vaccine target with the highest antigenicity. Having broad-spectrum conservancy with other H. pylori strains. Further, an immunoinformatic approach was used to predict an effective epitope-based vaccine against H. pylori. LpxF protein has been predicted to have linear and conformational B-cell epitopes and cytotoxic T-lymphocyte epitopes. Virtual screening of all the predicted 35 peptides against human TLR2 receptors resulted in identifying the top 5 peptides. Subsequent redocking with exhaustive parameters reported two peptides with docking energy of -6.9 kcal/mol with a good interaction pattern between the peptide-TLR2 complexes. Furthermore, a panel of two potent epitopes has been proposed that could be used to immunize populations against multiple H. pylori infections.

scholarly journals Identification of Potential Drug Targets in Helicobacter pylori Using In Silico Subtractive Proteomics Approaches and Their Possible Inhibition through Drug Repurposing

Pathogens ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 747 ◽  
Author(s):  
Kareem A. Ibrahim ◽  
Omneya M. Helmy ◽  
Mona T. Kashef ◽  
Tharwat R. Elkhamissy ◽  
Mohammed A. Ramadan
Keyword(s):  
Helicobacter Pylori ◽  
Drug Targets ◽  
Cellular Localization ◽  
Drug Repurposing ◽  
World Health ◽  
Potential Drug ◽  
Protein Pool ◽  
Subtractive Proteomics ◽  
H Pylori ◽  
Potential Drug Targets

The class 1 carcinogen, Helicobacter pylori, is one of the World Health Organization’s high priority pathogens for antimicrobial development. We used three subtractive proteomics approaches using protein pools retrieved from: chokepoint reactions in the BIOCYC database, the Kyoto Encyclopedia of Genes and Genomes, and the database of essential genes (DEG), to find putative drug targets and their inhibition by drug repurposing. The subtractive channels included non-homology to human proteome, essentiality analysis, sub-cellular localization prediction, conservation, lack of similarity to gut flora, druggability, and broad-spectrum activity. The minimum inhibitory concentration (MIC) of three selected ligands was determined to confirm anti-helicobacter activity. Seventeen protein targets were retrieved. They are involved in motility, cell wall biosynthesis, processing of environmental and genetic information, and synthesis and metabolism of secondary metabolites, amino acids, vitamins, and cofactors. The DEG protein pool approach was superior, as it retrieved all drug targets identified by the other two approaches. Binding ligands (n = 42) were mostly small non-antibiotic compounds. Citric, dipicolinic, and pyrophosphoric acid inhibited H. pylori at an MIC of 1.5–2.5 mg/mL. In conclusion, we identified potential drug targets in H. pylori, and repurposed their binding ligands as possible anti-helicobacter agents, saving time and effort required for the development of new antimicrobial compounds.

scholarly journals A Novel 3-Deoxy-d-manno-Octulosonic Acid (Kdo) Hydrolase That Removes the Outer Kdo Sugar of Helicobacter pylori Lipopolysaccharide

2005 ◽  
Vol 187 (10) ◽  
pp. 3374-3383 ◽  
Author(s):  
Christopher Stead ◽  
An Tran ◽  
Donald Ferguson ◽  
Sara McGrath ◽  
Robert Cotter ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Lipid A ◽  
In Vitro Assay ◽  
Spectrometric Analysis ◽  
Vitro Assay ◽  
The Core ◽  
H Pylori

ABSTRACT The lipid A domain anchors lipopolysaccharide (LPS) to the outer membrane and is typically a disaccharide of glucosamine that is both acylated and phosphorylated. The core and O-antigen carbohydrate domains are linked to the lipid A moiety through the eight-carbon sugar 3-deoxy-d-manno-octulosonic acid known as Kdo. Helicobacter pylori LPS has been characterized as having a single Kdo residue attached to lipid A, predicting in vivo a monofunctional Kdo transferase (WaaA). However, using an in vitro assay system we demonstrate that H. pylori WaaA is a bifunctional enzyme transferring two Kdo sugars to the tetra-acylated lipid A precursor lipid IVA. In the present work we report the discovery of a Kdo hydrolase in membranes of H. pylori capable of removing the outer Kdo sugar from Kdo2-lipid A. Enzymatic removal of the Kdo group was dependent upon prior removal of the 1-phosphate group from the lipid A domain, and mass spectrometric analysis of the reaction product confirmed the enzymatic removal of a single Kdo residue by the Kdo-trimming enzyme. This is the first characterization of a Kdo hydrolase involved in the modification of gram-negative bacterial LPS.

scholarly journals Mucosal FOXP3-Expressing CD4+ CD25high Regulatory T Cells in Helicobacter pylori-Infected Patients

2005 ◽  
Vol 73 (1) ◽  
pp. 523-531 ◽  
Author(s):  
Anna Lundgren ◽  
Erika Strömberg ◽  
Åsa Sjöling ◽  
Catharina Lindholm ◽  
Karin Enarsson ◽  
...  
Keyword(s):  
T Cells ◽  
Helicobacter Pylori ◽  
Regulatory T Cells ◽  
Gastric Adenocarcinoma ◽  
Cytotoxic T Lymphocyte ◽  
Duodenal Mucosa ◽  
Peptic Ulcers ◽  
Low Levels ◽  
H Pylori ◽  
And Function

ABSTRACT Helicobacter pylori chronically colonizes the stomach and duodenum and causes peptic ulcers or gastric adenocarcinoma in 10 to 20% of infected individuals. We hypothesize that the inability of patients to clear H. pylori infections is a consequence of active suppression of the immune response. Here we show that H. pylori-infected individuals have increased frequencies of CD4+ CD25high T cells in both the stomach and duodenal mucosa compared to uninfected controls. These cells have the phenotype of regulatory T cells, as they express FOXP3, a key gene for the development and function of regulatory T cells, as well as high levels of the cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) protein. In contrast, mucosal CD4+ CD25low and CD4+ CD25− cells express little FOXP3 mRNA and low levels of the CTLA-4 protein. Mucosal CD4+ CD25high T cells are present in individuals with asymptomatic H. pylori infections as well as in duodenal ulcer patients. The frequencies of CD4+ CD25high cells are also increased in the stomachs of H. pylori-infected patients with gastric adenocarcinoma, particularly in cancer-affected tissues. These findings suggest that regulatory T cells may suppress mucosal immune responses and thereby contribute to the persistence of H. pylori infections.

scholarly journals Two Distinct Antigenic Types of the Polysaccharide Chains of Helicobacter pylori Lipopolysaccharides Characterized by Reactivity with Sera from Humans with Natural Infection

2000 ◽  
Vol 68 (1) ◽  
pp. 151-159 ◽  
Author(s):  
Shin-Ichi Yokota ◽  
Ken-Ichi Amano ◽  
Yoshiko Shibata ◽  
Mizuho Nakajima ◽  
Miyuki Suzuki ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Lipid A ◽  
Inner Core ◽  
Antigenic Variation ◽  
Natural Infection ◽  
Clinical Isolates ◽  
Antigenic Epitope ◽  
Lewis Antigen ◽  
Human Sera ◽  
H Pylori

ABSTRACT We have purified lipopolysaccharides (LPS) from 10Helicobacter pylori clinical isolates which were selected on the basis of chemotype and antigenic variation. Data from immunoblotting of the purified LPS with sera from humans with H. pylori infection and from absorption of the sera with LPS indicated the presence of two distinct epitopes, termed the highly antigenic and the weakly antigenic epitopes, on the polysaccharide chains. Among 68 H. pylori clinical isolates, all smooth strains possessed either epitope; the epitopes were each carried by about 50% of the smooth strains. Thus, H. pylori strains can be classified into three types on the basis of their antigenicity in humans: those with smooth LPS carrying the highly antigenic epitope, those with smooth LPS carrying the weakly antigenic epitope, and those with rough LPS. Sera from humans with H. pylori infection could be grouped into three categories: those containing immunoglobulin G (IgG) antibodies against the highly antigenic epitope, those containing IgG against the weakly antigenic epitope, and those containing both specific IgGs; these groups made up about 50%, less than 10%, and about 40%, respectively, of all infected sera tested. In other words, IgG against the highly antigenic epitope were detected in more than 90% of H. pylori-infected individuals with high titers. IgG against the weakly antigenic epitope were detected in about 50% of the sera tested; however, the antibody titers were low. The two human epitopes existed independently from the mimic structures of Lewis antigens, which are known to be an important epitope ofH. pylori LPS. No significant relationship between the reactivities toward purified LPS of human sera and a panel of anti-Lewis antigen antibodies was found. Moreover, the reactivities of the anti-Lewis antigen antibodies, but not human sera, were sensitive to particular α-l-fucosidases. The human epitopes appeared to be located on O-polysaccharide chains containing endo-β-galactosidase-sensitive galactose residues as the backbone. Data from chemical analyses indicated that all LPS commonly contained galactose, glucosamine, glucose, and fucose (except one rough strain) as probable polysaccharide components, together with typical components of inner core and lipid A. We were not able to distinguish between the differences of antigenicity in humans by on the basis of the chemical composition of the LPS.

scholarly journals Cholesterol Enhances Helicobacter pylori Resistance to Antibiotics and LL-37

2011 ◽  
Vol 55 (6) ◽  
pp. 2897-2904 ◽  
Author(s):  
David J. McGee ◽  
Alika E. George ◽  
Elizabeth A. Trainor ◽  
Katherine E. Horton ◽  
Ellen Hildebrandt ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Lipid A ◽  
Polymyxin B ◽  
Defined Medium ◽  
Vital Role ◽  
Content Type ◽  
The Two Cultures ◽  
H Pylori ◽  
The Impact

ABSTRACTThe human gastric pathogenHelicobacter pyloristeals host cholesterol, modifies it by glycosylation, and incorporates the glycosylated cholesterol onto its surface via a cholesterol glucosyltransferase, encoded bycgt. The impact of cholesterol onH. pyloriantimicrobial resistance is unknown.H. pyloristrain 26695 was cultured in Ham's F12 chemically defined medium in the presence or absence of cholesterol. The two cultures were subjected to overnight incubations with serial 2-fold dilutions of 12 antibiotics, six antifungals, and seven antimicrobial peptides (including LL-37 cathelicidin and human alpha and beta defensins). Of 25 agents tested, cholesterol-grownH. pyloricells were substantially more resistant (over 100-fold) to nine agents than wereH. pyloricells grown without cholesterol. These nine agents included eight antibiotics and LL-37.H. pyloriwas susceptible to the antifungal drug pimaricin regardless of cholesterol presence in the culture medium. Acgtmutant retained cholesterol-dependent resistance to most antimicrobials but displayed increased susceptibility to colistin, suggesting an involvement of lipid A. Mutation oflpxE, encoding lipid A1-phosphatase, led to loss of cholesterol-dependent resistance to polymyxin B and colistin but not other antimicrobials tested. Thecgtmutant was severely attenuated in gerbils, indicating that glycosylation is essentialin vivo. These findings suggest that cholesterol plays a vital role in virulence and contributes to the intrinsic antibiotic resistance ofH. pylori.

scholarly journals In Vitro and In Vivo Antibacterial Activities of Patchouli Alcohol, a Naturally Occurring Tricyclic Sesquiterpene, against Helicobacter pylori Infection

2017 ◽  
Vol 61 (6) ◽  
Author(s):  
Y. F. Xu ◽  
D. W. Lian ◽  
Y. Q. Chen ◽  
Y. F. Cai ◽  
Y. F. Zheng ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Bacterial Resistance ◽  
Clinical Isolates ◽  
Potential Candidate ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Patchouli Alcohol ◽  
H Pylori

ABSTRACT This study further evaluated the in vitro and in vivo anti-Helicobacter pylori activities and potential underlying mechanism of patchouli alcohol (PA), a tricyclic sesquiterpene. In the in vitro assay, the capacities of PA to inhibit and kill H. pylori were tested on three standard strains at different pH values and on 12 clinical isolates. The effects of PA on H. pylori adhesion (and its alpA, alpB, and babA genes), motility (and its flaA and flaB genes), ultrastructure, and flagellation were investigated. Moreover, the H. pylori resistance to and postantibiotic effect (PAE) of PA were determined. Furthermore, the in vivo effects of PA on H. pylori eradication and gastritis were examined. Results showed that MICs of PA against three standard strains (pH 5.3 to 9) and 12 clinical isolates were 25 to 75 and 12.5 to 50 μg/ml, respectively. The killing kinetics of PA were time and concentration dependent, and its minimal bactericidal concentrations (MBCs) were 25 to 75 μg/ml. In addition, H. pylori adhesion, motility, ultrastructure, and flagellation were significantly suppressed. PA also remarkably inhibited the expression of adhesion genes (alpA and alpB) and motility genes (flaA and flaB). Furthermore, PA treatment caused a longer PAE and less bacterial resistance than clarithromycin and metronidazole. The in vivo study showed that PA can effectively eradicate H. pylori, inhibit gastritis, and suppress the expression of inflammatory mediators (COX-2, interleukin 1β, tumor necrosis factor alpha, and inducible nitric oxide synthase [iNOS]). In conclusion, PA can efficiently kill H. pylori, interfere with its infection process, and attenuate gastritis with less bacterial resistance, making it a potential candidate for new drug development.

scholarly journals Phase Variation in Helicobacter pylori Lipopolysaccharide

1998 ◽  
Vol 66 (1) ◽  
pp. 70-76 ◽  
Author(s):  
B. J. Appelmelk ◽  
B. Shiberu ◽  
C. Trinks ◽  
N. Tapsi ◽  
P. Y. Zheng ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Lipid A ◽  
Main Chain ◽  
Phase Variation ◽  
Polymeric Form ◽  
Altered Expression ◽  
Core Lipid ◽  
Parental Phenotype ◽  
H Pylori ◽  
Different Strains

Helicobacter pylori NCTC 11637 lipopolysaccharide (LPS) expresses the human blood group antigen Lewis x (Lex) in a polymeric form. Lex is β-d-galactose-(1-4)-[α-l-fucose-(1-3)]-β-d-acetylglucosamine. Schematically the LPS structure is (Lex) n -core-lipid A. In this report, we show that Lex expression is not a stable trait but that LPS displays a high frequency (0.2 to 0.5%) of phase variation, resulting in the presence of several LPS variants in one bacterial cell population. One type of phase variation implied the loss of α1,3-linked fucose, resulting in variants that expressed nonsubstituted polylactosamines (also called the i antigen), i.e., Lex minus fucose; LPS: (lactosamine) n -core-lipid A. The switch of Lex to i antigen was reversible. A second group of variants arose by loss of polymeric main chain which resulted in expression of monomeric Ley; LPS: (Ley)-core-lipid A. A third group of variants arose by acquisition of α1,2-linked fucose which hence expressed Lex plus Ley; LPS: (Ley)(Lex) n -core-lipid A. The second and third group of variants switched back to the parental phenotype [(Lex) n -core-lipid A] in lower frequencies. Part of the variation can be ascribed to altered expression levels of glycosyltransferase levels as assessed by assaying the activities of galactosyl-, fucosyl-, andN-acetylglucosaminyltransferases. Clearly phase variation increases the heterogeneity of H. pylori, and this process may be involved in generating the very closely related yet genetically slightly different strains that have been isolated from one patient.

Helicobacter pylorifrom asymptomatic hosts expressing heptoglycan but lacking Lewis O-chains: Lewis blood-group O-chains may play a role inHelicobacter pyloriinduced pathology

2001 ◽  
Vol 79 (4) ◽  
pp. 449-459 ◽  
Author(s):  
Mario A Monteiro ◽  
Frank St Michael ◽  
David A Rasko ◽  
Diane E Taylor ◽  
J Wayne Conlan ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Blood Group ◽  
Lipid A ◽  
Blood Groups ◽  
Blood Group Antigens ◽  
Chemical Structures ◽  
Lewis Blood Group ◽  
Membrane Antigens ◽  
H Pylori ◽  
Group Structures

Helicobacter pylori is a widespread Gram-negative bacterium responsible for the onset of various gastric pathologies and cancers in humans. A familiar trait of H. pylori is the production of cell-surface lipopolysaccharides (LPSs; O-chain [Formula: see text] core [Formula: see text] lipid A) with O-chain structures analogous to some mammalian histo-blood-group antigens, those being the Lewis determinants (Lea, Leb, Lex, sialyl Lex, Ley) and blood groups A and linear B. Some of these LPS antigens have been implicated as autoimmune, adhesion, and colonization components of H. pylori pathogenic mechanisms. This article describes the chemical structures of LPSs from H. pylori isolated from subjects with no overt signs of disease. Experimental data from chemical- and spectroscopic-based studies unanimously showed that these H. pylori manufactured extended heptoglycans composed of 2- and 3-linked D-glycero-α-D-manno-heptopyranose units and did not express any blood-group O-antigen chains. The fact that another H. pylori isolate with a similar LPS structure was shown to be capable of colonizing mice indicates that H. pylori histo-blood-group structures are not an absolute prerequisite for colonization in the murine model also. The absence of O-chains with histo-blood groups may cause H. pylori to become inept in exciting an immune response. Additionally, the presence of elongated heptoglycans may impede exposure of disease-causing outer-membrane antigens. These factors may render such H. pylori incapable of creating exogenous contacts essential for pathogenesis of severe gastroduodenal diseases and suggest that histo-blood groups in the LPS may indeed play a role in inducing a more severe H. pylori pathology.Key words: lipopolysaccharide, carbohydrates, glycobiology, Helicobacter pylori, histo-blood groups.

scholarly journals Helicobacter pylori treatment in the post-antibiotics era—searching for new drug targets

2020 ◽  
Vol 104 (23) ◽  
pp. 9891-9905 ◽  
Author(s):  
Paula Roszczenko-Jasińska ◽  
Marta Ilona Wojtyś ◽  
Elżbieta K. Jagusztyn-Krynicka
Keyword(s):  
Helicobacter Pylori ◽  
Drug Targets ◽  
Recent Effort ◽  
Antibiotic Resistant ◽  
New Drug ◽  
Group I ◽  
Key Points ◽  
New Antibiotics ◽  
Helicobacter Pylori Treatment ◽  
H Pylori

Abstract Helicobacter pylori, a member of Epsilonproteobacteria, is a Gram-negative microaerophilic bacterium that colonizes gastric mucosa of about 50% of the human population. Although most infections caused by H. pylori are asymptomatic, the microorganism is strongly associated with serious diseases of the upper gastrointestinal tract such as chronic gastritis, peptic ulcer, duodenal ulcer, and gastric cancer, and it is classified as a group I carcinogen. The prevalence of H. pylori infections varies worldwide. The H. pylori genotype, host gene polymorphisms, and environmental factors determine the type of induced disease. Currently, the most common therapy to treat H. pylori is the first line clarithromycin–based triple therapy or a quadruple therapy replacing clarithromycin with new antibiotics. Despite the enormous recent effort to introduce new therapeutic regimens to combat this pathogen, treatment for H. pylori still fails in more than 20% of patients, mainly due to the increased prevalence of antibiotic resistant strains. In this review we present recent progress aimed at designing new anti-H. pylori strategies to combat this pathogen. Some novel therapeutic regimens will potentially be used as an extra constituent of antibiotic therapy, and others may replace current antibiotic treatments. Key points • Attempts to improve eradication rate of H. pylori infection. • Searching for new drug targets in anti-Helicobacter therapies.

scholarly journals Differences in the Antigens ofHelicobacter pyloriStrains Influence on the Innate Immune Response in theIn VitroExperiments

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Miha Skvarc ◽  
Andreja Natasa Kopitar ◽  
Janko Kos ◽  
Natasa Obermajer ◽  
Bojan Tepes
Keyword(s):  
Immune Response ◽  
Helicobacter Pylori ◽  
Lipid A ◽  
Polymyxin B ◽  
Innate Immune ◽  
Effective Immune Response ◽  
Cathepsin X ◽  
Resistant Strains ◽  
H Pylori ◽  
Strain Dependent

The immune response toHelicobacter pyloriimportantly determines the pathogenesis of infection as well as the success of antibiotic eradication of the bacteria. Strains ofH. pyloriwere gathered from 14 patients who failed to eradicateH. pyloriinfection with antibiotics—therapy resistant strains (TRS)—or from patients who were able to eradicateH. pyloriinfection—therapy susceptible strains (TSS). The THP-1 cells were stimulated withH. pyloriantigens. Cathepsin X expression on THP-1 cells and concentration of cytokines in the supernatant of THP-1 cells were measured with a flow cytometer. TSSH. pyloriantigens increased the proportion of cathepsin X positive cells compared to TRSH. pyloriantigens. TSSH. pyloriantigens induced higher secretion of IL-12 and IL-6 compared to TRSH. pyloriantigens (P<0.001; 0.02). Polymyxin B, a lipid A inhibitor, lowered the secretion of IL-12 and IL-6 in TRS and TSS. We demonstrated aH. pyloristrain-dependent cathepsin X and cytokine expression that can be associated withH. pyloriresistance to eradication due to lack of effective immune response. Differences in lipid A ofH. pylorimight have an influence on the insufficient immune response, especially on phagocytosis.

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