Helicobacter pylori and gastric cancer

Binding of the Helicobacter pylori OipA causes apoptosis of host cells via modulation of Bax/Bcl-2 levels

The H. pylori outer inflammatory protein A (OipA) is an outer membrane protein that contributes to gastric inflammation. OipA is believed to affect intra-cellular signalling and modulate the host signalling pathways. The aim of the current study was to clarify the role of OipA in H. pylori pathogenesis and its effect on host cell signalling pathways. To this end, the oipA gene was isolated and inserted into cloning and expression vectors. The recombinant plasmid was transferred into an expression host to produce OipA, which was subsequently purified by affinity chromatography and used for antibody production. A confluent monolayer of gastric cell lines was treated with various concentrations of OipA and investigated for attachment, toxicity, and apoptosis and alterations in signalling pathways. OipA bound to gastric cell lines confirming its role in the attachment of H. pylori to host cells. The ratio of Bax/Bcl-2 and caspase3, 8, FasL in the host cells were assessed and the results showed that the Bax/Bcl-2 ratio as well as the level of cleaved-caspase 3 was elevated in OipA-treated cells. These findings suggest that OipA can bind and induce toxic events as well as triggering apoptotic cascade in host gastric cells through intrinsic pathway.

Relationship between ureB Sequence Diversity, Urease Activity and Genotypic Variations of Different Helicobacter pylori Strains in Patients with Gastric Disorders

Association of the severity of Helicobacter pylori induced diseases with virulence entity of the colonized strains was proven in some studies. Urease has been demonstrated as a potent virulence factor for H. pylori. The main aim of this study was investigation of the relationships of ureB sequence diversity, urease activity and virulence genotypes of different H. pylori strains with histopathological changes of gastric tissue in infected patients suffering from different gastric disorders. Analysis of the virulence genotypes in the isolated strains indicated significant associations between the presence of severe active gastritis and cagA+ (P = 0.039) or cagA/iceA1 genotypes (P = 0.026), and intestinal metaplasia and vacA m1 (P = 0.008) or vacA s1/m2 (P = 0.001) genotypes. Our results showed a 2.4-fold increased risk of peptic ulcer (95% CI: 0.483-11.93), compared with gastritis, in the infected patients who had dupA positive strains; however this association was not statistically significant. The results of urease activity showed a significant mean difference between the isolated strains from patients with PUD and NUD (P = 0.034). This activity was relatively higher among patients with intestinal metaplasia. Also a significant associa-tion was found between the lack of cagA and increased urease activity among the isolated strains (P = 0.036). While the greatest sequencevariation of ureB was detected in a strain from a patient with intestinal metaplasia, the sole determined amino acid change in UreB sequence (Ala201Thr, 30%), showed no influence on urease activity. In conclusion, the supposed role of H. pylori urease to form peptic ulcer and advancing of intestinal metaplasia was postulated in this study. Higher urease activity in the colonizing H. pylori strains that present specific virulence factors was indicated as a risk factor for promotion of histopathological changes of gastric tissue that advance gastric malignancy.

Association between cadherin-17 expression and pathological characteristics of gastric cancer: A meta-analysis

AIM: To construct a meta-analysis in order to examine the relationship between cadherin-17 (CDH17) and gastric cancer (GC).

METHODS: Related articles were selected by searching the following English or Chinese electronic databases: CINAHL, MEDLINE, Science Citation Index, the Chinese Journal Full-Text, and the Weipu Journal. Newcastle-Ottawa Scale (NOS) criteria were used to ensure consistency in reviewing and reporting results. Statistical analyses were conducted with Version 12.0 STATA statistical software.

RESULTS: Ultimately, 11 articles, with a total of 2,120 GC patients, were found to be eligible for study inclusion. In comparisons of GC patients by TNM stage (III-IV vs I-II: OR = 2.35, 95%CI: 1.15-4.825, P = 0.019), histologic grade (3-4 vs 1-2: OR = 3.48, 95%CI: 1.36-8.92, P = 0.009), invasion grade (T3-4 vs T1-2: OR = 2.86; 95%CI: 1.69-4.83; P = 0.000), and lymph node metastasis (positive vs negative: OR = 2.64; 95%CI: 1.33-5.27; P = 0.006), it was found that CDH17 showed more positive expressions in each of the more severe cases. Country-stratified analyses from all four experimental subgroups showed that high CDH17 expression levels may be related to GC among Chinese and Korean populations (all P < 0.05), with the exception of the invasion grade T3-4 vs T1-2 comparison, where the relation only held among the Chinese population (OR = 2.86, 95%CI: 1.69-4.83, P = 0.000).

CONCLUSION: Collectively, the data reflects the capacity of CDH17 in tumor proliferation and metastasis among GC patients.

EGF +61A/G polymorphism contributes to increased gastric cancer risk: evidence from a meta-analysis

Background

Epidermal growth factor (EGF) plays a pivotal role in cell proliferation, differentiation, and tumorigenesis of epithelial tissues. Variation of the EGF +61A/G (rs4444903) can lead to an alteration in EGF production and/or activity, which may result in individual susceptibility to gastric cancer. Studies investigating the association between EGF +61A/G polymorphism and gastric cancer risk produced inconsistent results. The aim of this study was to quantitatively summarize the evidence for such an association.

Methods

Eligible studies on the association between EGF +61A/G polymorphism and gastric cancer risk were identified by search of electronic databases including PubMed, EMBASE, Cochrane Library, and Chinese Biomedical Literature database (CBM). Data were extracted by two independent authors and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the association. Metaregression and subgroup analyses were performed to identify the source of heterogeneity.

Results

Finally, six case–control studies with 1547 gastric cancer cases and 2762 controls were eventually identified. Overall, significant increased gastric cancer risk was found when all studies were pooled in the meta-analysis (GG vs. AA: OR = 1.438, 95% CI 1.021–2.025, P = 0.038; GG + AG vs. AA: OR = 1.256, 95% CI 1.025–1.539, P = 0.028; GG vs. AG + AA: OR = 1.265, 95% CI 1.002–1.596, P = 0.048). In subgroup analysis by ethnicity, source of control, study quality, and HWE in controls, significant increased gastric cancer risk was observed in Asians, population-based studies, high quality studies, and studies consistent with HWE. In subgroup analysis according to tumor location, and histological type, significant association was observed in all subgroups.

Conclusions

This meta-analysis suggested that the EGF +61A/G polymorphism contributes to increased gastric cancer risk, especially in Asian populations. Further well-designed studies based on large sample size in diverse populations are needed to confirm this association.

Current evidences on XPC polymorphisms and gastric cancer susceptibility: a meta-analysis

Background

Reduced DNA repair capacities due to inherited polymorphisms may increase the susceptibility to cancers including gastric cancer. Previous studies investigating the association between Xeroderma Pigmentosum group C (XPC) gene polymorphisms and gastric cancer risk reported inconsistent results. We performed a meta-analysis to summarize the possible association.

Methods

All studies published up to January 2014 on the association between XPC polymorphisms and gastric cancer risk were identified by searching electronic databases PubMed, EMBASE, Cochrane library, and Chinese Biomedical Literature database (CBM). The association between XPC polymorphisms and gastric cancer risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs).

Results

Six studies with 1,355 gastric cancer cases and 2,573 controls were finally included in the meta-analysis. With respect to Lys939Gln polymorphism, we did not observe a significant association when all studies were pooled into the meta-analysis. When stratified by ethnicity, source of control, and study quality, statistical significant association was not detected in all subgroups. With respect to Ala499Val and PAT−/+polymorphisms, we also did not observe any significant association with gastric cancer risk in the pooled analysis.

Conclusions

This meta-analysis based on current evidences suggested that the XPC polymorphisms (Lys939Gln, Val499Arg, and PAT−/+) did not contribute to gastric cancer risk. Considering the limited sample size and ethnicity included in the meta-analysis, further larger scaled and well-designed studies are needed to confirm our results.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1485880312555069

Gastric biopsies: the gap between evidence-based medicine and daily practice in the management of gastric Helicobacter pylori infection

BACKGROUND

Many consider histology to be the gold standard for Helicobacter pylori detection. Because the number and distribution of H pylori organisms vary, particularly in patients taking proton pump inhibitors (PPIs), the American Gastroenterological Association recommends discontinuing PPIs two weeks before endoscopy, and taking biopsies from both the body and antrum.

OBJECTIVE

To assess the influence of clinical practice on the histopathological detection of H pylori infection.

METHODS

Electronic patient records were evaluated for the sites of gastric sampling and PPI use at endoscopy. One hundred fifty cases with biopsies taken from both antrum and body were randomly selected for pathological re-review with special stains. The gastric regions sampled, H pylori distribution and influence of clinical factors on pathological interpretation were assessed.

RESULTS

Between 2005 and 2010, 10,268 biopsies were taken to detect H pylori. Only one region was sampled in 60% of patients (antrum 47%, body 13%). Re-review of biopsies taken from both antrum and body indicated that the correct regions were sampled in only 85 (57%) patients. Of these, 54 were H pylori positive and 96 were H pylori negative. H pylori was present in the antrum in only 15% of the patients and body only in 21%. Of 96 H pylori-negative patients, two were reinterpreted as positive. Forty-seven per cent of patients were taking PPIs at endoscopy, contributing to both false-negative and false-positive diagnoses.

CONCLUSION

Despite national and international guidelines for managing H pylori infection, the American Gastroenterological Association guidelines are infrequently adhered to, with PPIs frequently contributing to false diagnosis; sampling one region only increases the likelihood of missing active infection by at least 15%.

Susceptibility genes are enriched in those of the herpes simplex virus 1/host interactome in psychiatric and neurological disorders

Herpes simplex virus 1 (HSV-1) can promote beta-amyloid deposition and tau phosphorylation, demyelination or cognitive deficits relevant to Alzheimer's disease or multiple sclerosis and to many neuropsychiatric disorders with which it has been implicated. A seroprevalence much higher than disease incidence has called into question any primary causal role. However, as also the case with risk-promoting polymorphisms (also present in control populations), any causal effects are likely to be conditional. During its life cycle, the virus binds to many proteins and modifies the expression of multiple genes creating a host/pathogen interactome involving 1347 host genes. This data set is heavily enriched in the susceptibility genes for multiple sclerosis (P = 1.3E-99) > Alzheimer's disease > schizophrenia > Parkinsonism > depression > bipolar disorder > childhood obesity > chronic fatigue > autism > and anorexia (P = 0.047) but not attention deficit hyperactivity disorder, a relationship maintained for genome-wide association study data sets in multiple sclerosis and Alzheimer's disease. Overlapping susceptibility gene/interactome data sets disrupt signalling networks relevant to each disease, suggesting that disease susceptibility genes may filter the attentions of the pathogen towards particular pathways and pathologies. In this way, the same pathogen could contribute to multiple diseases in a gene-dependent manner and condition the risk-promoting effects of the genes whose function it disrupts.

Helicobacter Pylori "Test-and-Treat" Strategy for Management of Dyspepsia: A Comprehensive Review

OBJECTIVES:

Deciding on whether the Helicobacter pylori test-and-treat strategy is an appropriate diagnostic–therapeutic approach for patients with dyspepsia invites a series of questions. The aim present article addresses the test-and-treat strategy and attempts to provide practical conclusions for the clinician who diagnoses and treats patients with dyspepsia.

METHODS:

Bibliographical searches were performed in MEDLINE using the keywords Helicobacter pylori, test-and-treat, and dyspepsia. We focused mainly on data from randomized controlled trials (RCTs), systematic reviews, meta-analyses, cost-effectiveness analyses, and decision analyses.

RESULTS:

Several prospective studies and decision analyses support the use of the test-and-treat strategy, although we must be cautious when extrapolating the results from one geographical area to another. Many factors determine whether this strategy is appropriate in each particular area. The test-and-treat strategy will cure most cases of underlying peptic ulcer disease, prevent most potential cases of gastroduodenal disease, and yield symptomatic benefit in a minority of patients with functional dyspepsia. Future studies should be able to stratify dyspeptic patients according to their likelihood of improving after treatment of infection by H. pylori.

CONCLUSIONS:

The test-and-treat strategy will cure most cases of underlying peptic ulcer disease and prevent most potential cases of gastroduodenal disease. In addition, a minority of infected patients with functional dyspepsia will gain symptomatic benefit. Several prospective studies and decision analyses support the use of the test-and-treat strategy. The test-and-treat strategy is being reinforced by the accumulating data that support the increasingly accepted idea that “the only good H. pylori is a dead H. pylori”.

Toxoplasmosis and Polygenic Disease Susceptibility Genes: Extensive Toxoplasma gondii Host/Pathogen Interactome Enrichment in Nine Psychiatric or Neurological Disorders

Toxoplasma gondii is not only implicated in schizophrenia and related disorders, but also in Alzheimer's or Parkinson's disease, cancer, cardiac myopathies, and autoimmune disorders. During its life cycle, the pathogen interacts with ~3000 host genes or proteins. Susceptibility genes for multiple sclerosis, Alzheimer's disease, schizophrenia, bipolar disorder, depression, childhood obesity, Parkinson's disease, attention deficit hyperactivity disorder (P  from  8.01E - 05  (ADHD)  to  1.22E - 71) (multiple sclerosis), and autism (P = 0.013), but not anorexia or chronic fatigue are highly enriched in the human arm of this interactome and 18 (ADHD) to 33% (MS) of the susceptibility genes relate to it. The signalling pathways involved in the susceptibility gene/interactome overlaps are relatively specific and relevant to each disease suggesting a means whereby susceptibility genes could orient the attentions of a single pathogen towards disruption of the specific pathways that together contribute (positively or negatively) to the endophenotypes of different diseases. Conditional protein knockdown, orchestrated by T. gondii proteins or antibodies binding to those of the host (pathogen derived autoimmunity) and metabolite exchange, may contribute to this disruption. Susceptibility genes may thus be related to the causes and influencers of disease, rather than (and as well as) to the disease itself.

Symptom-histopathology relation in upper GI endoscopy

OBJECTIVE

The purpose of this article is to examine the correlation between information obtained from patients before endoscopy and histopathological findings.

MATERIAL AND METHODS

One thousand, five hundred and thirty-six patients underwent upper GI endoscopy between January 2011-September 2012, without distinction of age and sex were included in the study. Patients with alarm symptoms, dyspepsia, epigastric pain, gastroesophageal reflux were recorded. Tissue samples taken for histopathological examination and H. pylori screening were evaluated by Giemsa stain. The information given by the patients and histopathological findings were comparatively evaluated.

RESULTS

Six hundred and twenty-four patients (40.6%) were male and 912 (59.4%) were female. Mean age was 45 years (18-90). H. pylori was positive in 416 patients with dyspepsia (58.8%), 172 patients with epigastric pain (54.4%), 52 patients with GER symptoms (28.3%) and 128 patients with alarm symptoms (50.8%). Four patients with dyspepsia (0.6%) and 20 patients with alarm symptoms (7.9%) were diagnosed with stomach cancer.

CONCLUSION

The main factor should be considered as the presence of at least one of the alarm symptoms when planning an upper GI endoscopy in a patient. In the presence of at least one of the alarm symptoms, an upper GI endoscopy should be performed regardless of age. Under the age of 50 and for patients without alarm symptoms, medical treatment can be tried before performing upper GI endoscopy. Patients with GER symptoms but not diagnosed as reflux esophagitis, should be treated long-term even when symptoms decline with initial treatment.

CYP2E1 RsaI/PstI polymorphism and gastric cancer susceptibility: meta-analyses based on 24 case-control studies

Background

Previous reports implicate CYP2E1 RsaI/PstI polymorphism as a possible risk factor for several cancers. Published studies on the relationship of CYP2E1 RsaI/PstI polymorphisms with the susceptibility to gastric cancer are controversial. This study aimed to determine this relationship accurately.

Methods

Meta-analyses that assessed the association of CYP2E1 RsaI/PstI variations with gastric cancer were conducted. Subgroup analyses on ethnicity, smoking status, alcohol consumption, and source of controls were also performed. Eligible studies up to Mar 2012 were identified.

Results

After rigorous searching and screening, 24 case-control studies comprising 3022 cases and 4635 controls were selected for analysis. The overall data failed to indicate the significant associations of CYP2E1 RsaI/PstI polymorphisms with the gastric cancer risk [c2 vs. c1: odds ratio (OR) = 1.06; 95% confidence interval (CI) = 0.88–1.28; c2c2 vs. c1c1: OR = 1.23; 95% CI = 0.78–1.92; c2c2+c1c2 vs. c1c1: OR = 0.93; 95% CI = 0.79–1.10]. Similar results were observed in the subgroup analyses on ethnicity, drinking status, and source of controls. However, in the subgroup analysis on smoking status, a borderline increase in cancer risk was found among long-term smokers (c2c2+c1c2 vs. c1c1: OR = 1.39; 95% CI = 1.00–1.92).

Conclusion

CYP2E1 RsaI/PstI polymorphisms may modify the susceptibility to gastric cancer among individuals who have a smoking history. Large and well-designed studies are needed to confirm this conclusion.

Prevalence of Helicobacter pylori vacA, cagA and iceA genotypes and correlation with clinical outcome

The aim of this study was to assess the genetic status of cagA, vacA subtype and iceA genotypes of Helicobacter pylori and the relationship with upper gastrointestinal diseases in Northeast China. Gastric biopsies were obtained from 378 patients with upper gastrointestinal diseases and 197 samples were used. The cagA, vacA alleles and iceA genotypes were determined by polymerase chain reaction. CagA was present in 176 (89.3%) of 197 patients. Of the 197 cases, 186 (94.4%) had vacA signal sequence s1c allele, 6 (3%) had s1a and 5 (2.5%) had s1b. The vacA s2 genotype was not detected in our study. VacA middle region sequences, m1 and m2, were found in 20 (10.2%) and 150 (76.1%), respectively. The allelic variant iceA1 (70.1%) was more prevalent than iceA2 (23.4%). The vacA allele s1am2 had a significant relationship with the presence of gastric cancer (p<0.05) and the iceA1 genotype was also associated with gastric cancer (p<0.05). These may be useful risk factors for upper gastrointestinal diseases.

Helicobacter pylori Eradication Therapy: Current Availabilities

Background. Though Helicobacter pylori (HP) infections have progressively declined throughout most of the industrialized countries, a gradual increase in failure of HP eradication treatments is observed. Aim. To critically review evidence on the efficacy of the therapeutic availabilities for HP eradication, as yet. Methods. A selection of Clinical Trials, Systematic Reviews and Meta-analyses within the time period 2010–2012, was performed through a Medline search. Previous references were included when basically supporting the first selection. Results. An increasing rise in HP resistance rates for antimicrobial agents is currently observed. Further causes of HP treatment failure include polymorphisms of the CYP 2C19, an increased body mass index (BMI), smoking, poor compliance and re-infections. Alternative recent approaches to standard triple therapy have been attempted to increase the eradication rate, including bismuth-containing quadruple therapy, non-bismuth containing quadruple therapy, sequential therapy and levofloxacin-containing regimens. Conclusions. The main current aims should be the maintenance of a high eradication rate (>85%) of HP and the prevention of any increase in antimicrobial resistance. In the next future, the perspective of a tailored therapy could optimize eradication regimens within the different countries.

MiR-135a targets JAK2 and inhibits gastric cancer cell proliferation

The role of tumor suppressors and cell cycle factors in gastric carcinogenesis are well understood; however, the post-transcriptional changes that affect gene expression in gastric cancer are poorly characterized. MiR-135a has been shown to play a role in Hodgkin lymphoma. The aim of this study was to investigate the expression and role of miR-135a in gastric cancer. Quantitative real-time PCR demonstrated that miR-135a expression is downregulated in the majority of human primary gastric cancer tissues (8/11; 73%), compared with pair-matched adjacent non-tumor tissues. Furthermore, compared with the nonmalignant gastric cell line, GES-1, miR-135a expression was substantially downregulated in gastric cancer cell lines of various degrees of differentiation. Target analysis indicated miR-135a directly regulates Janus kinase 2 (JAK2), a cytoplasmic tyrosine kinase involved in cytokine receptor signaling pathways. Overexpression of miR-135a significantly downregulated the expression of JAK2 protein and also reduced gastric cancer cell proliferation and colony formation in vitro. MiR-135a-mediated JAK2 downregulation also reduced p-STAT3 activation and cyclin D1 and Bcl-xL protein expression. This study suggests that miR-135a may function as a tumor suppressor via targeting JAK to repress p-STAT3 activation, reduce cyclin D1 and Bcl-xL expression and inhibit gastric cancer cell proliferation. These results imply that novel treatment approaches targeting miR-135a may potentially benefit patients with gastric cancer.