Inhibition of the type IV secretion system from antibiotic-resistant Helicobacter pylori clinical isolates supports the potential of Cagα as an anti-virulence target.

Helicobacter pylori resistance to antibiotics is a growing problem and it increasingly leads to treatment failure. While the bacterium is present worldwide, the severity of clinical outcomes is highly dependent on the geographical origin and genetic characteristics of the strains. One of the major virulence factors identified in H. pylori is the cag pathogenicity island (cagPAI), which encodes a type IV secretion system (T4SS) used to translocate effectors into human cells. Here, we investigated the genetic variability of the cagPAI among 13 antibiotic-resistant H. pylori strains that were isolated from patient biopsies in Québec. Seven of the clinical strains carried the cagPAI, but only four could be readily cultivated under laboratory conditions. We observed variability of the sequences of CagA and CagL proteins that are encoded by the cagPAI. All clinical isolates induce interleukin-8 secretion and morphological changes upon co-incubation with gastric cancer cells and two of them produce extracellular T4SS pili. Finally, we demonstrate that molecule 1G2, a small molecule inhibitor of the Cagα protein from the model strain H. pylori 26695, reduces interleukin-8 secretion in one of the clinical isolates. Co-incubation with 1G2 also inhibits the assembly of T4SS pili, suggesting a mechanism for its action on T4SS function.

Impact of Helicobacter pylori Virulence Factors on the Host Immune Response and Gastric Pathology.

Helicobacter pylori chronically infects nearly half the world's population, yet most of those infected remain asymptomatic throughout their lifetime. The outcome of infection-peptic ulcer disease or gastric cancer versus asymptomatic colonization-is a product of host genetics, environmental influences, and differences in bacterial virulence factors. Here, we review the current understanding of the cag pathogenicity island (cagPAI), the vacuolating cytotoxin (VacA), and a large family of outer membrane proteins (OMPs), which are among the best understood H. pylori virulence determinants that contribute to disease. Each of these virulence factors is characterized by allelic and phenotypic diversity that is apparent within and across individuals, as well as over time, and modulates inflammation. From the bacterial perspective, inflammation is probably a necessary evil because it promotes nutrient acquisition, but at the cost of reduction in bacterial load and therefore decreases the chance of transmission to a new host. The general picture that emerges is one of a chronic bacterial infection that is dependent on both inducing and carefully regulating the host inflammatory response. A better understanding of these regulatory mechanisms may have implications for the control of chronic inflammatory diseases that are increasingly common causes of human morbidity and mortality.

Role of NOD1 and ALPK1/TIFA Signalling in Innate Immunity Against Helicobacter pylori Infection.

The human pathogen Helicobacter pylori interacts intimately with gastric epithelial cells to induce inflammatory responses that are a hallmark of the infection. This inflammation is a critical precursor to the development of peptic ulcer disease and gastric cancer. A major driver of this inflammation is a type IV secretion system (T4SS) encoded by the cag pathogenicity island (cagPAI), present in a subpopulation of more virulent H. pylori strains. The cagPAI T4SS specifically activates signalling pathways in gastric epithelial cells that converge on the transcription factor, nuclear factor-κB (NF-κB), which in turn upregulates key immune and inflammatory genes, resulting in various host responses. It is now clear that H. pylori possesses several mechanisms to activate NF-κB in gastric epithelial cells and, moreover, that multiple signalling pathways are involved in these responses. Two of the dominant signalling pathways implicated in NF-κB-dependent responses in epithelial cells are nucleotide-binding oligomerisation domain 1 (NOD1) and a newly described pathway involving alpha-kinase 1 (ALPK1) and tumour necrosis factor (TNF) receptor-associated factor (TRAF)-interacting protein with forkhead-associated domain (TIFA). Although the relative roles of these two pathways in regulating NF-κB-dependent responses still need to be clearly defined, it is likely that they work cooperatively and non-redundantly. This chapter will give an overview of the various mechanisms and pathways involved in H. pylori induction of NF-κB-dependent responses in gastric epithelial cells, including a 'state-of-the-art' review on the respective roles of NOD1 and ALPK1/TIFA pathways in these responses.

TLR2, TLR4 and TLR10 Shape the Cytokine and Chemokine Release of H. pylori-Infected Human DCs.

Helicobacter pylori (H. pylori) is a stomach pathogen that persistently colonizes the gastric mucosa, often leading to chronic inflammation and gastric pathologies. Although infection with H. pylori is the primary risk factor for gastric cancer, the underlying mechanisms of pathogen persistence and consequential chronic inflammation are still not well understood. Conventional dendritic cells (cDCs), which are among the first immune cells to encounter H. pylori in the gastric lining, and the cytokines and chemokines they secrete, contribute to both acute and chronic inflammation. Therefore, this study aimed to unravel the contributions of specific signaling pathways within human CD1c+ cDCs (cDC2s) to the composition of secreted cytokines and chemokines in H. pylori infection. Here, we show that the type IV secretion system (T4SS) plays only a minor role in H. pylori-induced activation of cDC2s. In contrast, Toll-like receptor 4 (TLR4) signaling drives the secretion of inflammatory mediators, including IL-12 and IL-18, while signaling via TLR10 attenuates the release of IL-1ß and other inflammatory cytokines upon H. pylori infection. The TLR2 pathway significantly blocks the release of CXCL1 and CXCL8, while it promotes the secretion of TNFα and GM-CSF. Taken together, these results highlight how specific TLR-signaling pathways in human cDC2s shape the H. pylori-induced cytokine and chemokine milieu, which plays a pivotal role in the onset of an effective immune response.

Biochemical characterization of the Helicobacter pylori Cag Type 4 Secretion System protein CagN and its interaction partner CagM.

Highly virulent Helicobacter pylori strains contain the cag pathogenicity island (cagPAI). It codes for about 30 proteins forming a type IV secretion system (T4SS) which translocates the pro-inflammatory protein CagA into epithelial host cells. While CagA and various other Cag proteins have been extensively studied, several cagPAI proteins are poorly characterized or of unknown function. CagN (HP0538) is of unknown function but highly conserved in the cagPAI suggesting an important role. cagM (HP0537) is the first gene of the cagMN operon and its product is part of the CagT4SS core complex. Both proteins do not have detectable homologs in other type IV secretion systems. We have characterized the biochemical and structural properties of CagN and CagM and their interaction. We demonstrate by circular dichroism, Multi-Angle Light Scattering (MALS) and small angle X-ray scattering (SAXS) that CagN is a folded, predominantly monomeric protein with an elongated shape in solution. CagM is folded and forms predominantly dimers that are also elongated in solution. We found by various in vivo and in vitro methods that CagN and CagM directly interact with each other. CagM self-interacts stably with a low nanomolar KD and can form stable multimers. Finally, in vivo experiments show that deletion of CagM reduces the amounts of CagN and other outer CagPAI proteins in H. pylori cells.

Macrophages recognize the Helicobacter pylori type IV secretion system in the absence of toll-like receptor signalling.

Helicobacter pylori strains carrying the cag pathogenicity island (cagPAI) provoke an increased inflammatory response, conferring an increased risk of ulcer formation and carcinogenesis. How the immune system recognizes the presence of cagPAI positive strains is yet unclear. By comparing the transcriptional response of wild type and MyD88/Trif(-/-) bone marrow macrophages to infection with H. pylori, we found that the majority of regulated genes were dependent on toll-like receptor (TLR) signalling. To determine the role of TLR-independent responses, we analysed the transcriptome of MyD88/Trif(-/-) bone marrow macrophages at different time points after infection with cagPAI positive versus negative strains. We identified a group of genes that exhibited different kinetic behaviour depending on whether cagPAI was present. Analysis of their gene expression kinetics demonstrated that this responsiveness to cagPAI was observed only in MyD88/Trif(-/-) macrophages. This group of cagPAI-sensing genes was enriched for AU-rich element containing early response genes involved in immune regulation, including interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α). Recognition of cagPAI positive strains was found to be mediated by the type IV secretion system (cagT4SS), rather than its effector protein CagA. We hypothesize that anergic macrophages of the gastric mucosa initiate an innate immune response following detection of the T4SS of H. pylori.

Gastric lymphoma: association with Helicobacter pylori outer membrane protein Q (HopQ) and cytotoxic-pathogenicity activity island (CPAI) genes.

B-cell non-Hodgkin lymphoma (B-cell NHL) is the second commonest malignancy in the stomach. We determined the distribution of Helicobacter pylori outer membrane protein Q (HopQ) allelic type, cytotoxin-associated gene (cag)-pathogenicity activity island (cag-PAI) and vacuolation activating cytotoxin A (vacA) genes, respectively, in patients with B-cell NHL. We also compared them with their distribution in non-ulcer dyspepsia (NUD). H. pylori was cultured from gastric biopsy tissue obtained at endoscopy. Polymerase chain reaction was performed. Of 170 patients enrolled, 114 (63%) had NUD and 56 (37%) had B-cell NHL. HopQ type 1 was positive in 66 (58%) in NUD compared with 46 (82%) (P = 0·002) in B-cell NHL; HopQ type 2 was positive in 93 (82%) with NUD compared with 56 (100%) (P < 0·001) in B-cell NHL. Multiple HopQ types were present in 46 (40%) in NUD compared with 46 (82%) (P < 0·001) in B-cell NHL. CagA was positive in 48 (42%) in NUD vs. 50 (89%) (P < 0·001) in B-cell NHL; cagT was positive in 35 (31%) in NUD vs. 45 (80%) (P < 0·001) in B-cell NHL; left end of the cagA gene (LEC)1 was positive in 23 (20%) in NUD vs. 43 (77%) (P < 0·001) in B-cell NHL. VacAs1am1 positive in B-cell NHL in 48 (86%) (P < 0·001) vs. 50 (44%) in NUD, while s1am2 was positive in 20 (17%) in NUD vs. 46 (82%) (P < 0·001) in B-cell NHL. H. pylori strains with multiple HopQ allelic types, truncated cag-PAI evidenced by expression of cagA, cagT and cag LEC with virulent vacAs1 alleles are associated with B-cell NHL development.

Association of heterogenicity of Helicobacter pylori cag pathogenicity island with peptic ulcer diseases and gastric cancer.

OBJECTIVE: To investigate the frequency and integrity of certain cag pathogenicity island genes (cagPAI) in Helicobacter pylori strains and their association with peptic ulcer disease (PUD) and gastric cancer. MATERIAL AND METHODS: We enrolled 240 adult patients [120 with functional dyspepsia (FD), 50 with PUD and 70 with gastric cancer] undergoing upper gastrointestinal endoscopy. H. pylori infection was diagnosed when either culture or any two of the three tests (rapid urease test, histopathology and specific ureA PCR) were positive. DNA extracted from H. pylori isolates and positive gastric tissues were tested by PCR for the presence of different genes of cagPAI using specific primers. RESULTS: A total of 122 (51%) patients were H. pylori positive. Frequencies of cagPAI genes cagA, cagE, cagT and cagM in H. pylori strains from different groups of patients were as follows: functional dyspepsia 73, 83, 76 and 60%, PUD 70, 94, 91, 70% and gastric cancer 75, 95, 90 and 70%, respectively. Risk associated for the presence of PUD and gastric cancer with cagPAI genes cagE, cagT and cagM was 5.0-, 4.6- and 4.1- and 3.0-, 2.8- and 2.5-folds, respectively. Prevalence of intact cagPAI was significantly higher in PUD and gastric cancer compared to functional dyspepsia (PUD vs. functional dyspepsia, 71% vs. 38%, P = 0.01; gastric cancer vs. functional dyspepsia, 75% vs. 38%, P < 0.01). Intact cagPAI was associated with increased risk for the presence of PUD (odds ratio 5.2, 95% CI 2.4-11.3) and for the presence of gastric cancer (odds ratio 4.5, 95% CI 2.3-7.1). CONCLUSIONS: cagPAI integrity and its different genes are linked to different forms of gastric disease and so may have a role in pathogenesis, diagnosis and management.

Systematic analysis of phosphotyrosine antibodies recognizing single phosphorylated EPIYA-motifs in CagA of East Asian-type Helicobacter pylori strains.

BACKGROUND: Highly virulent strains of the gastric pathogen Helicobacter pylori encode a type IV secretion system (T4SS) that delivers the effector protein CagA into gastric epithelial cells. Translocated CagA undergoes tyrosine phosphorylation by members of the oncogenic c-Src and c-Abl host kinases at EPIYA-sequence motifs A, B and D in East Asian-type strains. These phosphorylated EPIYA-motifs serve as recognition sites for various SH2-domains containing human proteins, mediating interactions of CagA with host signaling factors to manipulate signal transduction pathways. Recognition of phospho-CagA is mainly based on the use of commercial pan-phosphotyrosine antibodies that were originally designed to detect phosphotyrosines in mammalian proteins. Specific anti-phospho-EPIYA antibodies for each of the three sites in CagA are not forthcoming. RESULTS: This study was designed to systematically analyze the detection preferences of each phosphorylated East Asian CagA EPIYA-motif by pan-phosphotyrosine antibodies and to determine a minimal recognition sequence. We synthesized phospho- and non-phosphopeptides derived from each predominant EPIYA-site, and determined the recognition patterns by seven different pan-phosphotyrosine antibodies using Western blotting, and also investigated representative East Asian H. pylori isolates during infection. The results indicate that a total of only 9-11 amino acids containing the phosphorylated East Asian EPIYA-types are required and sufficient to detect the phosphopeptides with high specificity. However, the sequence recognition by the different antibodies was found to bear high variability. From the seven antibodies used, only four recognized all three phosphorylated EPIYA-motifs A, B and D similarly well. Two of the phosphotyrosine antibodies preferentially bound primarily to the phosphorylated motif A and D, while the seventh antibody failed to react with any of the phosphorylated EPIYA-motifs. Control experiments confirmed that none of the antibodies reacted with non-phospho-CagA peptides and in accordance were able to recognize phosphotyrosine proteins in human cells. CONCLUSIONS: The results of this study disclose the various binding preferences of commercial anti-phosphotyrosine antibodies for phospho-EPIYA-motifs, and are valuable in the application for further characterization of CagA phosphorylation events during infection with H. pylori and risk prediction for gastric disease development.

CagA-mediated pathogenesis of Helicobacter pylori.

Helicobacter pylori has been described as the main etiologic agent of gastric cancer, causing a considerable rate of mortality and morbidity in human population across the world. Although the infection mainly begins asymptomatically, but simply develops to peptic ulcer, chronic gastritis, lymphoma of the gastric mucosa and eventually adenocarcinoma. The major pathological feature of H. pylori infection is due to the activity of the cytotoxin-associated gene A (CagA), a 125-140 kDa protein encoded by the cag pathogenicity island (cagPAI). CagA is also known as the first bacterial onco-protein, ranking the H. pylori-mediated adenocarcinoma as the second most deadly cancer type worldwide. Upon cytoplasmic translocation CagA undergoes interacting with numerous proteins in phosphorylation dependent and independent manners within the gastric epithelial cells. The profound effect of CagA on multiple intracellular pathways causes major consequences such as perturbation of intracellular actin trafficking, stimulation of inflammatory responses and disruption of cellular tight junctions. Such activities of CagA further participate in development of the hummingbird phenotype and gastric cancer. This review is sought to provide a structural and functional analysis of the CagA protein with focus on demonstrating the molecular basis of the mechanism of CagA intracellular translocation and its interaction with intracellular targets.

MEKK3 and TAK1 synergize to activate IKK complex in Helicobacter pylori infection.

Helicobacter pylori colonises the gastric epithelial cells of half of the world's population and represents a risk factor for gastric adenocarcinoma. In gastric epithelial cells H. pylori induces the immediate early response transcription factor nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-κB) and the innate immune response. We show that H. pylori induces in a type IV secretion system-dependent (T4SS) and cytotoxin associated gene A protein (CagA)-independent manner a transient activation of the inhibitor of NF-κB (IκBα) kinase (IKK)-complex. IKKα and IKKß expression stabilises the regulatory IKK complex subunit NF-κB essential modulator (NEMO). We provide evidence for an intimate mutual control of the IKK complex by mitogen-activated protein kinase kinase kinase 3 (MEKK3) and transforming growth factor ß activated kinase 1 (TAK1). TAK1 interacts transiently with the E3 ubiquitin ligase tumor necrosis factor receptor-associated factor 6 (TRAF6). Protein modifications in the TAK1 molecule, e.g. TAK1 autophosphorylation and K63-linked ubiquitinylation, administer NF-κB signalling including transient recruitment of the IKK-complex. Overall, our data uncover H. pylori-induced interactions and protein modifications of the IKK complex, and its upstream regulatory factors involved in NF-κB activation.

Association of CagPAI integrity with severeness of Helicobacter pylori infection in patients with gastritis.

BACKGROUND AND AIM: The Helicobacter pylori cag pathogenicity island (cagPAI) is involved in delivery of CagA effector protein and peptidoglycan into host cells and also in IL-8 induction in the human gastric tissue. Diversity of cagPAI may affect disease status and clinical outcome of the infected patients. Our study was aimed to investigate diversity of this island and its intactness in Iranian patients to investigate possible associations between cagPAI integrity and pathological changes of the infected tissue. MATERIAL/PATIENTS AND METHODS: Out of the 75 patients, H. pylori strains were obtained from 30 patients with severe active gastritis (SAG) (n=11), moderate chronic gastritis (CG) (n=14) and intestinal metaplasia/dysplasia (IM) (n=5). Intactness of the cagPAI was determined using 12 sets of primer pairs specific for functionally important loci of cagPAI by polymerase chain reaction (PCR). RESULTS: The cagPAI positive strains were significantly observed in patients with SAG (52.4%) in comparison to those presenting CG (33.3%) and IM (14.3%). In addition, the presence of intact cagPAI was 87.5% in H. pylori strains isolated from patients with SAG, which was higher than those obtained from patients with CG (12.5%) or IM (0%). A significant increase in the frequency of cagα-cagY and cagW-cagT segments, as exterior proteins of the CagPAI, was illustrated in strains from SAG patients compared with those from patients with CG. CONCLUSIONS: Overall, these results strongly proposed an association between the severity of histopathological changes and intactness of cagPAI in the gastric tissue of patients infected with H. pylori.

Roles of the components of the cag-pathogenicity island encoded type IV secretion system in Helicobacter pylori.

The Helicobacter pylori (H. pylori) cytotoxin-associated gene pathogenicity island (cagPAI) encodes 31 genes that assemble the cag type IV secretion system (T4SS) apparatus, which includes structures such as the outer membrane core complex, periplasmic ring, inner membrane complex and bacterial hairs. These proteins interact with each other to inject CagA into the host gastric epithelium. There are also individual unique functions that help H. pylori interfere with host cellular pathways, modulate the immune response and colonize the host for a long time. However, the functions of some of the proteins remain unclear. This review summarizes what is known about the structure and function of these auxiliary components and discusses their role in H. pylori pathogenesis.

[Box: see text].

Helicobacter pylori induces type 4 secretion system-dependent, but CagA-independent activation of IκBs and NF-κB/RelA at early time points.

Colonization of the gastric epithelium by Helicobacter pylori induces the transcription factor nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-κB) and the innate immune response. Virulent strains of H. pylori carry a cag pathogenicity island (cagPAI), which encodes a type IV secretion system (T4SS). Recent publications have shown controversial data regarding the role of the T4SS and the effector protein cytotoxin associated gene A (CagA), which becomes translocated by the T4SS into the eukaryotic epithelial cell, in H. pylori-induced NF-κB activation. Thus, this study analyses by using three different H. pylori strains (P1, B128 and G27) whether CagA is required to initiate activation of different molecules of inhibitors of kappa B (IκB) and the NF-κB transcription factor RelA. We provide experimental evidence that H. pylori induces phosphorylation of NF-κB inhibitors IκBα, IκBß and IκBɛ, and degradation of IκBα. Further, H. pylori stimulates phosphorylation of RelA at amino acids S536, S468 and S276, promotes DNA binding of RelA, and interleukin 8 (IL-8) gene expression in a T4SS-, but CagA-independent manner at early time points.

Hp0521 inhibited the virulence of H. pylori 26,695 strain via regulating CagA expression.

Hp0521 is the number of cag pathogenicity island (cagPAI) family in Helicobacter pylori (H. pylori, Hp), which encoded Cag2 protein. The aim of this study was to investigate the role of hp0521 on the H. pylori 26,695 strain. We constructed the recombinant prokaryotic expression plasmid pET-32a-hp0521 and pET-32a-hpc0521. Then, we co-cultured the H. pylori wild strain 26,695 and Δhp0521 strain with GES-1 cells to detect CagA protein transport and IL-8 secretion. We found that Δhp0521 mutation increased the expression of cagA, rpoB and promoted the transportation of CagA protein in GES-1 cells. In addition, we also observed that Δhp0521 mutation had no effect on other cagPAI protein stability and the expression of IL-8. Our findings suggested that hp0521 may down-regulated the expression of cagA, rpoB and inhibited the transportation of CagA protein in GES-1 cells and had no effect on growth.

Presence of cagPAI genes and characterization of vacA s, i and m regions in Helicobacter pylori isolated from Alaskans and their association with clinical pathologies.

Introduction. Gastric cancer is a health disparity in the Alaska Native people. The incidence of Helicobacter pylori infection, a risk factor for non-cardia gastric adenocarcinoma, is also high. Gastric cancer is partially associated with the virulence of the infecting strain.Aim. To genotype the vacA s, m and i and cag pathogenicity island (cagPAI) genes in H. pylori from Alaskans and investigate associations with gastropathy.Methodology. We enrolled patients with gastritis, peptic ulcer disease (PUD) and intestinal metaplasia (IM) in 1998-2005 and patients with gastric cancer in 2011-2013. Gastric biopsies were collected and cultured and PCR was performed to detect the presence of the right and left ends of the cagPAI, the cagA, cagE, cagT and virD4 genes and to genotype the vacA s, m and i regions.Results. We recruited 263 people; 22 (8 %) had no/mild gastritis, 121 (46 %) had moderate gastritis, 40 (15%) had severe gastritis, 38 (14 %) had PUD, 30 (11 %) had IM and 12 (5 %) had gastric cancer. H. pylori isolates from 150 (57%) people had an intact cagPAI; those were associated with a more severe gastropathy (P≤0.02 for all comparisons). H. pylori isolates from 77 % of people had either the vacA s1/i1/m1 (40 %; 94/234) or s2/i2/m2 (37 %; 86/234) genotype. vacA s1/i1/m1 was associated with a more severe gastropathy (P≤0.03 for all comparisons).Conclusions. In this population with high rates of gastric cancer, we found that just over half of the H. pylori contained an intact cagPAI and 40 % had the vacA s1/i1/m1 genotype. Infection with these strains was associated with a more severe gastropathy.

Genetic diversity and virulence characteristics of Helicobacter pylori isolates in different human ethnic groups.

Helicobacter pylori is the most predominant bacterium in almost 50% of the world's population and colonization causes a persistent inflammatory response leading to chronic gastritis. It shows high genetic diversity and individuals generally harbour a distinct bacterial population. With the advancement of whole-genome sequencing technology, new H. pylori subpopulations have been identified that show admixture between various H. pylori strains. Genotypic variation of H. pylori may be related to the presence of virulence factors among strains and is associated with different outcomes of infection in different individuals. This review summarizes the genetic diversity in H. pylori strain populations and its virulence characteristics responsible for variable outcomes in different ethnic groups.

The heterogeneic distribution of Helicobacter pylori cag pathogenicity island reflects different pathologies in multiracial Malaysian population.

BACKGROUND: Helicobacter pylori harbouring cag-pathogenicity island (cagPAI) which encodes type IV secretion system (T4SS) and cagA virulence gene are involved in inflammation of the gastric mucosa. We examined all the 27 cagPAI genes in 88 H. pylori isolates from patients of different ethnicities and examined the association of the intactness of cagPAI region with histopathological scores of the gastric mucosa. RESULTS: 96.6% (n=85) of H. pylori isolates were cagPAI-positive with 22.4% (19/85) having an intact cagPAI, whereas 77.6% (66/85) had a partial/rearranged cagPAI. The frequency of cag2 and cag14 were found to be significantly higher in H. pylori isolated from Malays, whereas cag4 was predominantly found in Chinese isolates. The cag24 was significantly found in higher proportions in Malay and Indian isolates than in Chinese isolates. The intactness of cagPAI region showed an association with histopathological scores of the gastric mucosa. Significant association was observed between H. pylori harbouring partial cagPAI with higher density of bacteria and neutrophil activity, whereas strains lacking cagPAI were associated with higher inflammatory score. CONCLUSIONS: The genotypes of H. pylori strains with various cagPAI rearrangement associated with patients' ethnicities and histopathological scores might contribute to the pathogenesis of H. pylori infection in a multi-ethnic population.

Helicobacter pylori cagE, cagG, and cagM can be a prognostic marker for intestinal and diffuse gastric cancer.

It is known that Helicobacter pylori is the main cause of peptic ulceration and gastric cancer. However, there is a lack of information on whether H. pylori strains may differ in gastric cancer histological subtypes. This study aimed to investigate different H. pylori strains considering six cag Pathogenicity Island - cagPAI genes (cagA, cagE, cagG, cagM, cagT, and virb11), and vacuolating cytotoxin - vacA alleles, and their relation to gastric cancer histologic subtypes. For this purpose, tumor samples from 285 patients with gastric carcinoma were used. H. pylori infection and genotypes were determined by polymerase chain reaction (PCR). H. pylori was detected in 93.9% of gastric tumors. For comparative analyzes between histopathological subtypes considering H. pylori cagPAI genes the strains were grouped according to the vacA s1/s2 alleles. In the vacAs1 group, the strains cagA(-)cagE(+), cagA(+)cagE(+)cagG(+), cagA(+)cagM(+), or only cagE(+) strains were more frequent in the intestinal subtype (P = .009; P = .024; P = .046, respectively). In contrast, cagM(+)cagG(+)cagA(-) and cagE(-) were associated with diffuse tumors (P = .036), highlighting the presence of cagE in the development of intestinal tumors, and the presence of cagG and absence of cagE in diffuse tumors. Furthermore, WEKA software and Decision Tree (CART) analyses confirmed these findings, in which cagE presence was associated with intestinal tumors, and cagE absence and cagG(+) with diffuse tumors. In conclusion our results showed that vacAs1 (cagG + cagM) strains, mainly cagG positive with cagE absence, were relevant in the studied population for the diffuse outcome, while the presence of cagE was relevant for the intestinal outcome. These findings suggest the relevance of these H. pylori genes as potential markers for gastric cancer histological outcomes.

Which genotype of Helicobacter pylori-cagA or cagE-Is better associated with gastric Cancer risk? Lessons from an extremely high-risk area in Iran.

The association of the H. pylori cagA- /cagE-positive genotypes with the risk of gastric cancer (GC) in Ardabil-a high-risk area in North-West Iran-was assessed. Genotyping was performed in DNA from fresh gastric biopsies (N = 218). Occurrence of H. pylori infection was 85.32% (186/218). The total frequency of the cagA+vs. cagA-, cagE+vs. cagE-, cagA+/cagE-vs. AGCs (all genotype combinations), cagA-/cagE+vs. AGCs, cagA-/cagE-vs. AGCs, cagA+/cagE+vs. AGCs, cagA+/cagE-vs. cagA-/cagE+, and cagA+/cagE+vs. cagA-/cagE- genotypes was 102/186 (54.8%), 89/186 (47.8%), 38/186 (20.4%), 25/186 (13.4), 59/186 (31.7%), 64/186 (34.4%), 38/63 (38.63%), and 64/123 (52.0%), respectively. The cagE+vs. cagE- (59.6% (65/109) in GC vs. 31.2% (24/77) in non-atrophic gastritis, NAG) and the cagA+/cagE+vs. cagA-/cagE- genotypes (66.7% (40/60) in GC vs. 38.1% (24/63) in NAG) showed an increased association with the risk of GC in Ardabil (odds ratio [OR] = 3.262, 95% confidence interval [CI]: 1.763-6.038, p = .0001 and OR = 3.250; 95% CI: 1.552-6.808, p = .002, respectively). We propose that the H. pylori cagE+ but not cagA+ genotype significantly increased the risk of GC in this extremely high-risk population. Therefore, it may play a significant role in determining H. pylori-related clinical outcome.