A Comprehensive Sequence and Disease Correlation Analyses for the C-Terminal Region of CagA Protein of Helicobacter pylori

Chronic Helicobacter pylori infection is known to be associated with the development of peptic ulcer, gastric cancer and gastric lymphoma. Currently, the bacterial factors of H. pylori are reported to be important in the development of gastroduodenal diseases. CagA protein, encoded by the cagA, is the best studied virulence factor of H. pylori. The pathogenic CagA protein contains a highly polymorphic Glu-Pro-Ile-Tyr-Ala (EPIYA) repeat region in the C-terminal. This repeat region is reported to be involved in the pathogenesis of gastroduodenal diseases. The segments containing EPIYA motifs have been designated as segments A, B, C, and D; however the classification and disease relation are still unclear. This study used 560 unique CagA sequences containing 1,796 EPIYA motifs collected from public resources, including 274 Western and 286 East Asian strains with clinical data obtained from 433 entries. Fifteen types of EPIYA or EPIYA-like sequences are defined. In addition to four previously reported major segment types, several minor segment types (e.g., segment B′, B′′) and more than 30 sequence types (e.g., ABC, ABD) were defined using our classification method. We confirm that the sequences from Western and East Asian strains contain segment C and D, respectively. We also confirm that strains with two EPIYA segment C have a greater chance of developing gastric cancer than those with one segment C. Our results shed light on the relationships between the types of CagAs, the country of origin of each sequence type, and the frequency of gastric disease.     

A Specific A/T Polymorphism in Western Tyrosine Phosphorylation B-Motifs Regulates Helicobacter pylori CagA Epithelial Cell Interactions

Helicobacter pylori persistently colonizes the human stomach, with mixed roles in human health. The CagA protein, a key host-interaction factor, is translocated by a type IV secretion system into host epithelial cells, where its EPIYA tyrosine phosphorylation motifs (TPMs) are recognized by host cell kinases, leading to multiple host cell signaling cascades. The CagA TPMs have been described as type A, B, C or D, each with a specific conserved amino acid sequence surrounding EPIYA. Database searching revealed strong non-random distribution of the B-motifs (including EPIYA and EPIYT) in Western H. pylori isolates. In silico analysis of Western H. pylori CagA sequences provided evidence that the EPIYT B-TPMs are significantly less associated with gastric cancer than the EPIYA B-TPMs. By generating and using a phosphorylated CagA B-TPM-specific antibody, we demonstrated the phosphorylated state of the CagA B-TPM EPIYT during H. pylori co-culture with host cells. We also showed that within host cells, CagA interaction with phosphoinositol 3-kinase (PI3-kinase) was B-TPM tyrosine-phosphorylation-dependent, and the recombinant CagA with EPIYT B-TPM had higher affinity to PI3-kinase and enhanced induction of AKT than the isogenic CagA with EPIYA B-TPM. Structural modeling of the CagA B-TPM motif bound to PI3-kinase indicated that the threonine residue at the pY+1 position forms a side-chain hydrogen bond to N-417 of PI3-kinase, which cannot be formed by alanine. During co-culture with AGS cells, an H. pylori strain with a CagA EPIYT B-TPM had significantly attenuated induction of interleukin-8 and hummingbird phenotype, compared to the isogenic strain with B-TPM EPIYA. These results suggest that the A/T polymorphisms could regulate CagA activity through interfering with host signaling pathways related to carcinogenesis, thus influencing cancer risk.     

CagA phosphorylation-dependent MMP-9 expression in gastric epithelial cells

Background: Infection of cagA‐positive Helicobacter pylori is associated with increased expression of MMPs in gastric epithelial cells. The role of phosphorylated CagA in the induction of MMP‐9, a protease‐degrading basement membrane, in gastric epithelial cells has not been clearly defined yet. The aim of this study is to analyze whether the presence of CagA and its phosphorylation status play a role in increased expression of MMP‐9 in gastric epithelial cells. Materials and Methods: Induction of MMP‐9 secretion was analyzed in gastric epithelial AGS cells harboring CagA with or without EPIYA motif, which is injected by H. pylori or ectopically expressed. In addition, signaling pathways involved in the CagA‐dependent MMP‐9 production have been studied. Results: The 147C strain of H. pylori expressing tyrosine‐phosphorylated CagA (EPIYA present) induced higher MMP‐9 secretion by AGS cells than the 147A strain expressing non‐tyrosine‐phosphorylated CagA (EPIYA absent). In addition, in bacteria‐free CagA‐inducible AGS cells, expression of wild‐type CagA induced more MMP‐9 secretion than phosphorylation‐resistant CagA. Inhibition of CagA phosphorylation by the Src family kinase inhibitor PP1 downregulated CagA‐mediated MMP‐9 secretion. Knockdown of SHP‐2 phosphatase dramatically reduced MMP‐9 secretion. ERK inhibitors, PD98059 and U0126, and NF‐κB pathway inhibitors, sulfasalazine and N‐acetyl‐l ‐cysteine, also inhibited MMP‐9 expression. Conclusion: These results support a model whereby the EPIYA motif of CagA is phosphorylated by Src family kinases in gastric epithelial cells, which initiates activation of SHP‐2. In addition, they suggest that the resultant activation of ERK pathway along with CagA‐dependent NF‐κB activation is critical for the induction of MMP‐9 secretion.     

Helicobacter pylori from Gastric Cancer and Duodenal Ulcer Show Same Phylogeographic Origin in the Andean Region in Colombia

Background

A recent report has shown that the phylogenetic origin of Helicobacter pylori based on multi-locus sequence typing (MLST) was significantly associated with the severity of gastritis in Colombia. However, the potential relationship between phylogenetic origin and clinical outcomes was not examined in that study. If the phylogenetic origin rather than virulence factors were truly associated with clinical outcomes, identifying a population at high risk for gastric cancer in Colombia would be relatively straightforward. In this study, we examined the phylogenetic origins of strains from gastric cancer and duodenal ulcer patients living in Bogota, Colombia.

Methods

We included 35 gastric cancer patients and 31 duodenal ulcer patients, which are considered the variant outcomes. The genotypes of cagA and vacA were determined by polymerase chain reaction. The genealogy of these Colombian strains was analyzed by MLST. Bacterial population structure was analyzed using STRUCTURE software.

Results

H. pylori strains from gastric cancer and duodenal ulcer patients were scattered in the phylogenetic tree; thus, we did not detect any difference in phylogenetic distribution between gastric cancer and duodenal ulcer strains in the hpEurope group in Colombia. Sixty-six strains, with one exception, were classified as hpEurope irrespective of the cagA and vacA genotypes, and type of disease. STRUCTURE analysis revealed that Colombian hpEurope strains have a phylogenetic connection to Spanish strains.

Conclusions

Our study showed that a phylogeographic origin determined by MLST was insufficient for distinguishing between gastric cancer and duodenal ulcer risk among hpEurope strains in the Andean region in Colombia. Our analysis also suggests that hpEurope strains in Colombia were primarily introduced by Spanish immigrants.     

H. pylori predictors and outcomes among adults undergoing upper endoscopy at a Jamaican teaching hospital: A cross-sectional study

Background

Recent data on the prevalence of H. pylori infection in Jamaica are lacking. It is postulated that there has been a decline in the prevalence of H. pylori infection and its associated complications. We determined sociodemographic characteristics, prevalence of H. pylori infection and clinical outcomes among adults undergoing esophagogastroduodenoscopy (EGD) and histology at the University Hospital of the West Indies (UHWI) between May 2018 and December 2020.

Materials and methods

A cross-sectional study of patients (≥18 years old), who underwent EGD and histological evaluation for H. pylori infection, was conducted. Associations of H. pylori positivity and gastric cancer with sociodemographic/clinical variables and endoscopic findings were determined by stepwise logistic regression using backward selection. Unadjusted and adjusted odds ratios with related 95% confidence intervals (Cis) were calculated for H. pylori positivity and gastric cancer status.

Results

There were 323 participants (mean age 58.6 ± 17.8 years, 54.2% females). H. pylori prevalence was 22.2% (n = 70 of 315), 5.6% had gastric neoplasia (GN), 15.5% gastric atrophy, 11.4% intestinal metaplasia and 3.7% dysplasia on histology. Mucositis (64.5%), gastric ulcer (14.9%), and duodenal ulcer (13.9%) were the most common endoscopic findings. Participants with peptic ulcer disease (PUD) (unOR = 4.0; p = .017), gastric cancer (unOR = 9.5; p = .003), gastric atrophy (unOR = 12.8; p < .001), and intestinal metaplasia (unOR = 5.0; p < .001) had a significantly higher odds of being H. pylori positive, but after multivariable analyses only gastric atrophy remained significant (aOR = 27.3; p < .001). Participants with mucositis had a significantly lower odds of gastric cancer (unOR 0.1; p = .035) while participants with dysplasia had significantly higher odds (unOR 8.0; p = .042), but these were no longer significant after multivariable analyses (aOR = 0.2; p = .156 and aOR = 18.9; p = .070, respectively).

Conclusions

Histology based prevalence of H. pylori infection is lower than previously reported in Jamaica. Gastric atrophy is a significant predictor of H. pylori positivity.     

Dynamics of the Cag‐type IV secretion system of Helicobacter pylori as studied by bacterial co‐infections

Many pathogenic Gram‐negative bacteria possess type IV secretion systems (T4SS) to inject effector proteins directly into host cells to modulate cellular processes to their benefit. The human bacterial pathogen Helicobacter pylori, a major aetiological agent in the development of chronic gastritis, duodenal ulcer and gastric carcinoma, harbours the cag‐T4SS to inject the cytotoxin associated Antigen (CagA) into gastric epithelial cells. This results in deregulation of major signalling cascades, actin‐cytoskeletal rearrangements and eventually gastric cancer. We show here that a pre‐infection with live H. pylori has a dose‐dependent negative effect on the CagA translocation efficiency of a later infecting strain. This effect of the ‘first’ strain was independent of any of its T4SS, the vacuolating cytotoxin (VacA) or flagella. Other bacterial pathogens, e.g. pathogenic Escherichia coli, Campylobacter jejuni, Staphylococcus aureus, or commensal bacteria, such as lactobacilli, were unable to interfere with H. pylori's CagA translocation capacity in the same way. This interference was independent of the β1 integrin receptor availability for H. pylori, but certain H. pylori outer membrane proteins, such as HopI, HopQ or AlpAB, were essential for the effect. We suggest that the specific interference mechanism induced by H. pylori represents a cellularresponse to restrict and control CagA translocation into a host cell to control the cellular damage.     

A Potential Association between Helicobacter pylori CagA EPIYA and Multimerization Motifs with Cytokeratin 18 Cleavage Rate during Early Apoptosis

Background and Aims: Helicobacter pylori is a highly diverse pathogen, which encounters epithelial cells as the initial defense barrier during its lifelong infection. The structure of epithelial cells can be disrupted through cleavage of microfilaments. Cytokeratin 18 (CK18) is an intermediate filament, the cleavage of which is considered an early event during apoptosis following activation of effector caspases. Methods: Helicobacter pylori strains were isolated from 76 dyspeptic patients. cagA 3’ variable region and CagA protein status were analyzed by PCR and western blotting, respectively. Eight hours post‐co‐culture of AGS cells with different H. pylori strains, flow cytometric analysis was performed using M30 monoclonal antibody specific to CK18 cleavage‐induced neo‐epitope. Results: Higher rates of CK18 cleavage were detected during co‐culture of AGS cells with H. pylori strains bearing greater numbers of cagA EPIYA‐C and multimerization (CM) motifs. On the other hand, H. pylori strains with greater numbers of EPIYA‐B relative to EPIYA‐C demonstrated a decrease in CK18 cleavage rate. Thus, H. pylori‐mediated cleavage of CK18 appeared proportional to the number of CagA EPIYA‐C and CM motifs, which seemed to be downplayed in the presence of EPIYA‐B motifs. Conclusions: Our observation associating the heterogeneity of cagA variants with the potential of H. pylori strains in the induction of CK18 cleavage as an early indication of apoptosis in gastric epithelial cells supports the fact that apoptosis may be a type‐specific trait. However, additional cagA‐targeted experiments are required to clearly identify the role of EPIYA and CM motifs in apoptosis and/or the responsible effector molecules.     

Helicobacter pylori Infection in Thailand: A Nationwide Study of the CagA Phenotype

Background

The risk to develop gastric cancer in Thailand is relatively low among Asian countries. In addition, the age-standardized incidence rate (ASR) of gastric cancer in Thailand varies with geographical distribution; the ASR in the North region is 3.5 times higher than that in the South region. We hypothesized that the prevalence of H. pylori infection and diversity of CagA phenotype contributes to the variety of gastric cancer risk in various regions of Thailand.

Methods

We conducted a nationwide survey within Thailand. We determined H. pylori infection prevalence by detecting H. pylori, using histochemical and immunohistochemical methods. The anti-CagA antibody and anti-East-Asian type CagA antibody (α-EAS Ab), which showed high accuracy in several East Asian countries, were used to determine CagA phenotype.

Results

Among 1,546 patients from four regions, including 17 provinces, the overall prevalence of H. pylori infection was 45.9% (710/1,546). Mirroring the prevalence of H. pylori infection, histological scores were the lowest in the South region. Of the 710 H. pylori-positive patients, 93.2% (662) were immunoreactive with the anti-CagA antibody. CagA-negative strain prevalence in the South region was significantly higher than that in other regions (17.9%; 5/28; p < 0.05). Overall, only 77 patients (11.6%) were immunoreactive with the α-EAS Ab. There were no differences in the α-EAS Ab immunoreactive rate across geographical regions.

Conclusions

This is the first study using immunohistochemistry to confirm H. pylori infections across different regions in Thailand. The prevalence of East-Asian type CagA H. pylori in Thailand was low. The low incidence of gastric cancer in Thailand may be attributed to the low prevalence of precancerous lesions. The low incidence of gastric cancer in the South region might be associated with the lower prevalence of H. pylori infection, precancerous lesions, and CagA-positive H. pylori strains, compared with that in the other regions.     

p27(kip1) upregulated by hnRNPC1/2 antagonizes CagA (a virulence factor of Helicobacter pylori)-mediated pathogenesis

Background and Aims: Infection by Helicobacter pylori is one of the major contributing factors of chronic active gastritis and peptic ulcer and is closely associated with the occurrence and progression of gastric cancer. CagA protein is a major virulence factor of H. pylori that interacts with SHP‐2, a true oncogene, to interfere with cellular signaling pathways; CagA also plays a crucial role in promoting the carcinogenesis of gastric epithelial cells. However, currently, the molecular mechanisms of gastric epithelial cells that antagonize CagA pathogenesis remain inconclusive. Methods: We showed that AGS gastric cancer cells transfected with CagA exhibited the inhibition of proliferation and increased activity of caspase 3/7 using two‐dimensional gel electrophoresis and secondary mass spectrometry (MS/MS). Results: It was found that the AGS gastric cancer cells stably expressing CagA displayed significantly increased the expression of 16 proteins, including hnRNPC1/2. Further analysis revealed that hnRNPC1/2 significantly boosted the expression of the p27^kip1 protein. Conclusion: Our data suggested that hnRNPC1/2 upregulates p27^kip1 expression and the subsequent suppression of cell proliferation and induction of apoptosis, thereby providing an important mechanism whereby gastric epithelial cells antagonize CagA‐mediated pathogenesis.     

Analysis of a β-helical region in the p55 domain of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> vacuolating toxin

Background  

Helicobacter pylori is a gram-negative bacterium that colonizes the human stomach and contributes to the development of gastric cancer and peptic ulcer disease. VacA, a toxin secreted by H. pylori, is comprised of two domains, designated p33 and p55. Analysis of the crystal structure of the p55 domain indicated that its structure is predominantly a right-handed parallel β-helix, which is a characteristic of autotransporter passenger domains. Substitution mutations of specific amino acids within the p33 domain abrogate VacA activity, but thus far, it has been difficult to identify small inactivating mutations within the p55 domain. Therefore, we hypothesized that large portions of the p55 domain might be non-essential for vacuolating toxin activity. To test this hypothesis, we introduced eight deletion mutations (each corresponding to a single coil within a β-helical segment spanning VacA amino acids 433-628) into the H. pylori chromosomal vacA gene.     

Geographic distribution of methyltransferases of Helicobacter pylori: evidence of human host population isolation and migration

Background  

Helicobacter pylori colonizes the human stomach and is associated with gastritis, peptic ulcer, and gastric cancer. This ubiquitous association between H. pylori and humans is thought to be present since the origin of modern humans. The H. pylori genome encodes for an exceptional number of restriction and modifications (R-M) systems. To evaluate if R-M systems are an adequate tool to determine the geographic distribution of H. pylori strains, we typed 221 strains from Africa, America, Asia, and Europe, and evaluated the expression of different 29 methyltransferases.     

Early detection of gastric cancer after Helicobacter pylori eradication due to endoscopic surveillance

Background

Helicobacter pylori eradication therapy is commonly performed to reduce the incidence of gastric cancer. However, gastric cancer is occasionally discovered even after successful eradication therapy. Therefore, we examined the prognosis of gastric cancer patients, diagnosed after successful H. pylori eradication therapy.

Materials and Methods

All‐cause death rates and gastric cancer‐specific death rates in gastric cancer patients who received successful H. pylori eradication treatment was tracked and compared to rates in patients who did not receive successful eradication therapy.

Results

In total, 160 gastric cancer patients were followed‐up for up to 11.7 years (mean 3.5 years). Among them, 53 gastric cancer patients received successful H. pylori eradication therapy prior to gastric cancer diagnosis. During the follow‐up period, 11 all‐cause deaths occurred. In the successful eradication group, the proportion of patients with cancer stage I was higher. The proportions of patients who received curative endoscopic therapy and endoscopic examination in the 2 years prior to gastric cancer diagnosis were also higher in the successful eradication group. Kaplan–Meier analysis of all‐cause death and gastric cancer‐specific death revealed a lower death rate in patients in the successful eradication group (P = .0139, and P = .0396, respectively, log‐rank test). The multivariate analysis showed that endoscopy within 2 years before cancer diagnosis is associated with stage I cancer.

Conclusions

Possible early discovery of gastric cancer after H. pylori eradication due to regular endoscopic surveillance may contribute to better prognosis of patients with gastric cancer.     

The association of garlic with Helicobacter pylori infection and gastric cancer risk: A systematic review and meta‐analysis

Background

Garlic may be protective against Helicobacter pylori infection and gastric cancer development. We conducted this study to quantitatively update evidence on garlic intake and gastric cancer with the inclusion of most recent cohort studies and qualitatively summarize epidemiological studies of garlic consumption and Helicobacter pylori infection.

Materials and Methods

PubMed, Embase, MEDLINE, and Cochrane Library were searched on April 2018. We conducted a meta‐analysis to determine whether garlic intake reduced gastric cancer risk using random‐effect models and a systematic review to summarize evidence on the association between garlic consumption and Helicobacter pylori infection. Risk of bias was assessed using tools of Cochrane risk of bias and Robins‐I for randomized and nonrandomized studies, respectively.

Results

Meta‐analysis of 18 studies (142 921 subjects) demonstrated high garlic consumption (as comparing the highest category to the lowest) was associated with a reduced gastric cancer risk (OR = 0.51, 95% CI = 0.44‐0.57). This association became nonsignificant if only derived from the prospective studies (OR = 0.95, 95% CI = 0.66‐1.24). Thirteen studies (4889 participants) were included in the systematic review for garlic consumption and Helicobacter pylori infection; ten of which found no significant results. The majority of these studies were poor in quality given the small sample size and high risk of bias.

Conclusions

Pooled evidence, mainly from case‐control studies, suggested a significant inverse association of garlic intake with gastric cancer risk. Given the limitations of included studies, current epidemiological evidence is not sufficient to reach any definite conclusion regarding the association of garlic with Helicobacter pylori infection.     

The HP0256 gene product is involved in motility and cell envelope architecture of <Emphasis Type="Italic">Helicobacter pylori</Emphasis>

Background  

Helicobacter pylori is the causative agent for gastritis, and peptic and duodenal ulcers. The bacterium displays 5-6 polar sheathed flagella that are essential for colonisation and persistence in the gastric mucosa. The biochemistry and genetics of flagellar biogenesis in H. pylori has not been fully elucidated. Bioinformatics analysis suggested that the gene HP0256, annotated as hypothetical, was a FliJ homologue. In Salmonella, FliJ is a chaperone escort protein for FlgN and FliT, two proteins that themselves display chaperone activity for components of the hook, the rod and the filament.     

Helicobacter Pylori infection of the gallbladder and the risk of chronic cholecystitis and cholelithiasis: A systematic review and meta‐analysis

Background

Helicobacter pylori is coexisted with various diseases, including chronic gastritis, ulcer, and gastric cancer. Besides, chronic cholecystitis and cholelithiasis are extremely widespread over the world, which are considered as high health‐care cost burdens of digestive diseases. Epidemiologic evidence on Helicobacter pylori infection in gallbladder increasing the risk of biliary diseases has been contradictory.

Aim

Conduct a meta‐analysis of overall studies and investigate an association between Helicobacter pylori infection of the gallbladder with chronic cholecystitis/cholelithiasis.

Methods

We used PubMed, EMBASE, and Cochrane library databases to identify all published studies before August 2017. Pooled odds ratios (OR) and corresponding 95% confidence intervals (CIs) were obtained using the random effects model. Heterogeneity, sensitivity, and stratified analyses were also performed.

Results

Eighteen studies involving 1544 participants and 1061 biliary cases with chronic cholecystitis/cholelithiasis were included. Helicobacter pylori infection of the gallbladder was significantly associated with an increased risk of chronic cholecystitis and cholecystitis (OR = 3.022; 95% CI, 1.897‐4.815; I² = 20.1%). In addition, country‐based subgroup analysis also showed a positive association between Helicobacter pylori positivity and chronic cholecystitis/cholelithiasis risk. The ORs (95% CIs) for Asian and non‐Asian region studies were 3.75 (1.83‐7.71) and 2.25 (1.29‐3.89), respectively.

Conclusion

This meta‐analysis suggests that infection of the gallbladder with Helicobacter pylori is closely related to an increased risk of chronic cholecystitis and cholelithiasis.     

Normalization of phospholipids concentration of the gastric mucosa was observed in patients with peptic ulcer after eradication of Helicobacter pylori

Background. Phospholipids concentration in the gastric mucosa decreased in patients with Helicobacter pylori infection. The aim of this study is to examine the effects of eradication of H. pylori on decreasing the phospholipids concentration in the gastric mucosa in patients with gastric or duodenal ulcer. Materials and Methods. Phospholipids (phosphatidylcholine, phosphatidylethanolamine, and sphingonomyeline) were measured in biopsy specimens from the antrum and corpus using thin‐layer chromatography. In H. pylori positive patients with gastric ulcer (n = 26) and duodenal ulcer (n = 13), and H. pylori negative controls (n = 20), the biopsy specimens were obtained before and 3 months after eradication. Eradication was performed using lansoprazole, amoxycillin, and clarithromycin. Results. Compared with the H. pylori negative control group, the concentrations of phosphatidylcholine and phosphatidylethanolamine decreased significantly in the gastric ulcer group in both antrum and corpus mucosa, and in the duodenal ulcer group in antrum mucosa. This decrease returned to the control level after eradication. Conclusions. This study demonstrates that the eradication of H. pylori in patients with peptic ulcer normalized the decrease of phosphatidylcholine and phosphatidylethanolamine in the gastric mucosa.     

Analysis of key genes and signaling pathways involved in Helicobacter pylori‐associated gastric cancer based on The Cancer Genome Atlas database and RNA sequencing data

Background

Helicobacter pylori (H. pylori) infection is associated with the development of gastric cancer, although the mechanism is unclear. Herein, this study aimed to clarify the key genes and signaling pathways involved in H. pylori pathogenesis based on The Cancer Genome Atlas (TCGA) database and RNA sequencing analysis.

Materials and Methods

Forty‐nine gastric cancer samples (16 with H. pylori and 33 without H. pylori) and 35 cancer‐adjacent normal samples from TCGA database were analyzed by bioinformatics. The differentially expressed genes between H. pylori‐positive and H. pylori‐negative patients were verified in 18 gastric cancer (GC) samples (9 with H. pylori and 9 without H. pylori), which were analyzed using RNA sequencing. Survival analysis was carried out to explore associations between the differentially expressed genes and prognosis. Bioinformatics analysis was performed to determine the signaling pathways associated with H. pylori.

Results

The baseline level of clinical features from TCGA database and RNA sequencing showed no differences between the H. pylori‐positive and H. pylori‐negative GC groups (P > 0.05). TP53 was shown to be upregulated in the H. pylori‐positive group in both TCGA database and RNA sequencing data, which also showed higher expression in the GC tissues than in adjacent normal tissues (P < 0.05). CCDC151, CHRNB2, GMPR2, HDGFRP2, and VSTM2L were shown to be downregulated in the H. pylori‐positive group by both TCGA database and RNA sequencing, which also showed lower expression in the GC tissues than in adjacent normal tissues (P < 0.05). GC patients with low expression levels of HDGFRP2 had a poor prognosis (P < 0.05). Thirty‐three signaling pathways and 10 biological processes were found to be positively associated with H. pylori infection (P < 0.05, FDR < 0.05).

Conclusions

These results indicate that some genes (TP53, CCDC151, CHRNB2, GMPR2, HDGFRP2, VSTM2L) and previously unidentified signaling pathways (eg, the Hippo signaling pathway) might play an important role in H. pylori‐associated GC.     

Helicobacter pylori CagA containing ITAM-like sequences localized to lipid rafts negatively regulates VacA-induced signaling in vivo

Background. Helicobacter pylori CagA is injected into the host cell and tyrosine‐phosphorylated. We examined tyrosine‐phosphorylation sites of CagA, as well as the function of CagA proteins in vivo and in vitro. Methods. After proteolytic digestion of CagA with lysyl endopeptidase, CagA tyrosine‐phosphorylation sites were determined using quadropolar time‐of‐flight (Q‐TOF) mass spectrometry analysis. Specific anti‐pY CagA polyclonal and anti‐CagA monoclonal antibodies were used to examine gastric mucosal biopsy specimens from H. pylori infected patients. Results. Mass spectrometry identified five crucial tyrosine‐phosphorylation sites of CagA at Tyr893, Tyr912, Tyr965, Tyr999, and Tyr1033 within the five repeated EPIYA sequences of H. pylori (NCTC11637)‐infected AGS cells. CagA protein also had an immuno‐receptor tyrosine‐based activation motif (ITAM)‐like amino acid sequences in the 3′ region of the cagA, E PIY ATI x₂₇EIY ATI , which closely resembled the ITAM. CagA proteins: (i) were localized to the 1% TritonX‐100 resistant membrane fraction (lipid rafts); (ii) formed a cluster of phosphorylated CagA protein complexes; (iii) associated with tyrosine‐phosphorylated GIT1/Cat1 (G protein‐coupled receptor kinase‐interactor 1/Cool‐associated tyrosine‐phosphorylated 1), substrate molecules of receptor type protein‐tyrosine phosphatase (RPTPζ/β), which is the receptor of VacA; and (iv) were involved in a delay and negative regulation of VacA‐induced signal. Furthermore, immunohistochemical staining of gastric mucosal biopsy specimens provided strong evidence that tyrosine‐phosphorylated CagA is found together with CagA at the luminal surface of gastric foveola in vivo. Conclusion. These findings suggest an important role for CagA containing ITAM‐like sequences in the pathogenesis of H. pylori‐related disease.     

Fifth Chinese National Consensus Report on the management of Helicobacter pylori infection

Background

Since the ‘Fourth Chinese National Consensus Report on the management of H. pylori infection’ was published in 2012, three important consensuses (Kyoto global consensus report on H. pylori gastritis, The Toronto Consensus for the Treatment of H. pylori Infection in Adults and Management of H. pylori infection—the Maastricht V/Florence Consensus Report) have been published regarding the management of H. pylori infection.

Materials and Methods

A Delphi method was adopted to develop the consensus of relevant ‘statements’. First, the established ‘statements’ were sent to experts via email. Second, after undergoing two rounds of consultation, the initial statements were discussed face to face and revised in the conference item by item on 16 December 2016. Finally, 21 core members of conferees participated in the final vote of statements. Voting for each statement was performed using an electronic system with levels of agreements shown on the screen in real time.

Results

Consensus contents contained a total of 48 “statements” and related 6 parts, including indications for H. pylori eradication, diagnosis, treatment, H. pylori and gastric cancer, H. pylori infection in special populations, H. pylori and gastrointestinal microbiota.

Conclusions

Recommendations are provided on the basis of the best available evidence.