Meta-analysis of the relationship between cagA seropositivity and gastric cancer

Helicobacter pylori Immunoproteomic Profiles in Gastric Cancer

Chronic Helicobacter pylori infection is the major risk factor for gastric cancer (GC). However, only some infected individuals develop this neoplasia. Previous H. pylori serology studies have been limited by investigating small numbers of candidate antigens. Therefore, we evaluated humoral responses to a nearly complete H. pylori immunoproteome (1527 proteins) among 50 GC cases and 50 controls using Nucleic Acid Programmable Protein Array (NAPPA). Seropositivity was defined as median normalized intensity ≥2 on NAPPA, and 53 anti-H. pylori antibodies had >10% seroprevalence. Anti-GroEL exhibited the greatest seroprevalence (77% overall), which agreed well with ELISA using whole-cell lysates of H. pylori cells. After an initial screen by H. pylori-NAPPA, we discovered and verified that 12 antibodies by ELISA in controls had ≥15% of samples with an optical reading value exceeding the 95th percentile of the GC group. ELISA-verified antibodies were validated blindly in an independent set of 100 case-control pairs. As expected, anti-CagA seropositivity was positively associated with GC (odds ratio, OR = 5.5; p < 0.05). After validation, six anti-H. pylori antibodies showed lower seropositivity in GC, with ORs ranging from 0.44 to 0.12 (p < 0.05): anti-HP1118/Ggt, anti-HP0516/HsIU, anti-HP0243/NapA, anti-HP1293/RpoA, anti-HP0371/FabE, and anti-HP0875/KatA. Among all combinations, a model with anti-Ggt, anti-HslU, anti-NapA, and anti-CagA had an area under the curve of 0.73 for discriminating GC vs. controls. This study represents the first comprehensive assessment of anti-H. pylori humoral profiles in GC. Decreased responses to multiple proteins in GC may reflect mucosal damage and decreased bacterial burden. The higher prevalence of specific anti-H. pylori antibodies in controls may suggest immune protection against GC development.

The ALPK1/TIFA/NF-κB axis links a bacterial carcinogen to R-loop-induced replication stress

Exposure of gastric epithelial cells to the bacterial carcinogen Helicobacter pylori causes DNA double strand breaks. Here, we show that H. pylori-induced DNA damage occurs co-transcriptionally in S-phase cells that activate NF-κB signaling upon innate immune recognition of the lipopolysaccharide biosynthetic intermediate β-ADP-heptose by the ALPK1/TIFA signaling pathway. DNA damage depends on the bi-functional RfaE enzyme and the Cag pathogenicity island of H. pylori, is accompanied by replication fork stalling and can be observed also in primary cells derived from gastric organoids. Importantly, H. pylori-induced replication stress and DNA damage depend on the presence of co-transcriptional RNA/DNA hybrids (R-loops) that form in infected cells during S-phase as a consequence of β-ADP-heptose/ ALPK1/TIFA/NF-κB signaling. H. pylori resides in close proximity to S-phase cells in the gastric mucosa of gastritis patients. Taken together, our results link bacterial infection and NF-κB-driven innate immune responses to R-loop-dependent replication stress and DNA damage.

The bacterial pathogen Helicobacter pylori is known for its ability to induce DNA double-strand breaks in the genome of its target cells. Here, we show that H. pylori-induced DNA damage and replication stress occurs in S-phase cells as a result of R-loop-mediated transcription/replication conflicts that are triggered by activation of the ALPK1/TIFA/NF-κB signaling axis.

Development of Helicobacter pylori Whole-Proteome Arrays and Identification of Serologic Biomarkers for Noncardia Gastric Cancer in the MCC-Spain Study

BACKGROUND

Helicobacter pylori (H. pylori) is a bacterial carcinogen and the leading risk factor for noncardia gastric cancer (NCGC). Detecting antibodies against specific H. pylori proteins in peripheral blood can be applied to characterize infection and determine disease associations. Most studies analyzing the association between H. pylori infection and gastric cancer have focused on previously identified antigens, predominantly the virulence factor cytotoxin-associated gene A (CagA). Selecting antigens in an unbiased approach may, however, allow the identification of novel biomarkers.

METHODS

Using a combination of multiple spotting technique and cell-free, on-chip protein expression, we displayed the H. pylori genome (strain 26695) on high-density microarrays. Immunogenic proteins were identified by serum pool incubations and henceforth analyzed in individual samples. To test its applicability, we used sera from a multicase-control (MCC)-Spain study. Serologic responses between NCGC cases and controls were assessed by conditional logistic regression estimating ORs and 95% confidence intervals.

RESULTS

We successfully expressed 93% of the 1,440 H. pylori open reading frames in situ. Of these, 231 (17%) were found to be immunogenic. By comparing 58 NCGC cases with 58 matched controls, we confirmed a higher seroprevalence of CagA among cases (66%) than controls (31%). We further identified a potential novel marker, the Helicobacter outer membrane protein A (HopA).

CONCLUSIONS

In this study, we provide evidence that our H. pylori whole-proteome microarray offers a platform for unbiased de novo identification of serologic biomarkers.

IMPACT

Given its versatile workflow, antibody responses against other H. pylori strains and possible associations with diverse H. pylori-related outcomes can be systematically analyzed.

Racial Differences in Helicobacter pylori CagA Sero-prevalence in a Consortium of Adult Cohorts in the United States

BACKGROUND

Prevalence of Helicobacter pylori (H. pylori) infection, the main risk factor for gastric cancer, has been decreasing in the United States; however, there remains a substantial racial disparity. Moreover, the time-trends for prevalence of CagA-positive H. pylori infection, the most virulent form, are unknown in the U.S.

POPULATION

We sought to assess prevalence of CagA-positive H. pylori infection over time by race in the United States.

METHODS

We utilized multiplex serology to quantify antibody responses to H. pylori antigens in 4,476 participants across five cohorts that sampled adults from 1985 to 2009. Using log-binomial regression models, we calculated prevalence ratios and 95% confidence intervals for the association between H. pylori-CagA sero-prevalence and birth year by race.

RESULTS

African Americans were three times more likely to be H. pylori-CagA sero-positive than Whites. After adjustment, H. pylori-CagA sero-prevalence was lower with increasing birth year among Whites (P trend = 0.001), but remained stable for African Americans. When stratified by sex and education separately, the decline in H. pylori-CagA sero-positivity among Whites remained only for females (P trend < 0.001) and was independent of educational attainment. Among African Americans, there was no difference by sex; furthermore, sero-prevalence increased with increasing birth year among those with a high school education or less (P = 0.006).

CONCLUSIONS

Among individuals in the United States born from the 1920s to 1960s, H. pylori-CagA sero-prevalence has declined among Whites, but not among African Americans.

IMPACT

Our findings suggest a widening racial disparity in the prevalence of the most virulent form of H. pylori, the main cause of gastric cancer.

Regional variations in Helicobacter pylori infection, gastric atrophy and gastric cancer risk: The ENIGMA study in Chile

BACKGROUND

Regional variations in gastric cancer incidence are not explained by prevalence of Helicobacter pylori, the main cause of the disease, with several areas presenting high H. pylori prevalence but low gastric cancer incidence. The IARC worldwide H. pylori prevalence surveys (ENIGMA) aim at systematically describing age and sex-specific prevalence of H. pylori infection around the world and generating hypotheses to explain regional variations in gastric cancer risk.

METHODS

We selected age- and sex-stratified population samples in two areas with different gastric cancer incidence and mortality in Chile: Antofagasta (lower rate) and Valdivia (higher rate). Participants were 1-69 years old and provided interviews and blood for anti-H. pylori antibodies (IgG, VacA, CagA, others) and atrophy biomarkers (pepsinogens).

RESULTS

H. pylori seroprevalence (Age-standardized to world population) and antibodies against CagA and VacA were similar in both sites. H. pylori seroprevalence was 20% among children <10 years old, 40% among 10-19 year olds, 60% in the 20-29 year olds and close to or above 80% in those 30+ years. The comparison of the prevalence of known and potential H. pylori cofactors in gastric carcinogenesis between the high and the low risk area showed that consumption of chili products was significantly higher in Valdivia and daily non-green vegetable consumption was more common in Antofagasta. Pepsinogen levels suggestive of gastric atrophy were significantly more common and occurred at earlier ages in Valdivia, the higher risk area. In a multivariate model combining both study sites, age, chili consumption and CagA were the main risk factors for gastric atrophy.

CONCLUSIONS

The prevalence of H. pylori infection and its virulence factors was similar in the high and the low risk area, but atrophy was more common and occurred at younger ages in the higher risk area. Dietary factors could partly explain higher rates of atrophy and gastric cancer in Valdivia.

IMPACT

The ENIGMA study in Chile contributes to better understanding regional variations in gastric cancer incidence and provides essential information for public health interventions.

Microbiome dysbiosis in cancer: Exploring therapeutic strategies to counter the disease

Cancer being a multiplex disease which involves many genomic and physiological alterations that occur consistently in the cancerous tissue, making the treatment and management of the disease even more complicated. The human gut microbiota (GM) harbors collective genomes of microbes comprising of trillions of bacteria along with fungi, archaea, and viruses that have the tendency to affect the development and progression of cancer. Moreover, inter-microbial interactions, diversity and distinct differences among the GM populations could influence the course of disease, making the microbiome an ideal target or to be modulated in such a way so as to improve cancer therapeutics with better efficacy and reduced toxicity. Current review focuses upon exploring the association of gut microbiota with the progression of cancer for which a structured search of bibliographic databases for peer-reviewed research literature has been carried out using focused review questions and inclusion/exclusion criteria. Through this review one could envisage a wide-spectrum role of microbiota in maintaining host metabolism, immune homeostasis paving the way for an anticancer diagnostic and therapeutic solution that has the potential to counter the menace of anti-cancer drug resistance as well.

Helicobacter pylori-induced inflammation masks the underlying presence of low-grade dysplasia on gastric lesions

BACKGROUND

Helicobacter pylori (H. pylori) infection has been associated with a long-term risk of precancerous gastric conditions (PGC) even after H. pylori eradication.

AIM

To investigate the efficacy of High-Resolution White-Light Endoscopy with Narrow-Band Imaging in detecting PGC, before/after H. pylori eradication.

METHODS

We studied 85 consecutive patients with H. pylori-related gastritis with/without PGC before and 6 mo after proven H. pylori eradication. Kimura-Takemoto modified and endoscopic grading of gastric intestinal metaplasia classifications, were applied to assess the endoscopic extension of atrophy and intestinal metaplasia. The histological result was considered to be the gold standard. The Sydney System, the Operative-Link on Gastritis-Assessment, and the Operative-Link on Gastric-Intestinal Metaplasia were used for defining histological gastritis, atrophy and intestinal metaplasia, whereas dysplasia was graded according to World Health Organization classification. Serum anti-parietal cell antibody and anti-intrinsic factor were measured when autoimmune atrophic gastritis was suspected.

RESULTS

After H. pylori eradication histological signs of mononuclear/polymorphonuclear cell infiltration and Mucosal Associated Lymphoid Tissue-hyperplasia, disappeared or decreased in 100% and 96.5% of patients respectively, whereas the Operative-Link on Gastritis-Assessment and Operative-Link on Gastric-Intestinal Metaplasia stages did not change. Low-Grade Dysplasia prevalence was similar on random biopsies before and after H. pylori eradication (17.6% vs 10.6%, P = 0.19), but increased in patients with visible lesions (0% vs 22.4%, P < 0.0001). At a multivariate analysis, the probability for detecting dysplasia after resolution of H. pylori-related active inflammation was higher in patients with regression or reduction of Mucosal Associated Lymphoid Tissue hyperplasia, greater alcohol consumption, and anti-parietal cell antibody and/or anti-intrinsic factor positivity [odds ratio (OR) = 3.88, 95% confidence interval (CI): 1.31-11.49, P = 0.01; OR = 3.10, 95%CI: 1.05-9.12, P = 0.04 and OR = 5.47, 95%CI: 1.33-22.39, P < 0.04, respectively].

CONCLUSION

High-Resolution White-Light Endoscopy with Narrow-Band Imaging allows an accurate diagnosis of Low-Grade Dysplasia on visible lesions after regression of H. pylori-induced chronic gastritis. Patients with an overlap between autoimmune/H. pylori-induced gastritis may require more extensive gastric mapping.

Helicobacter pylori patient isolates from South Africa and Nigeria differ in virulence factor pathogenicity profile and associated gastric disease outcome

Helicobacter pylori is a gram-negative, spiral-shaped bacterial pathogen and the causative agent for gastritis, peptic ulcer disease and classified as a WHO class I carcinogen. While the prevalence of H. pylori infections in Africa is among the highest in the world, the incidence of gastric cancer is comparably low. Little is known about other symptoms related to the H. pylori infection in Africa and the association with certain phenotypes of bacterial virulence. We established a network of study sites in Nigeria (NG) and South Africa (ZA) to gain an overview on the epidemiological situation. In total 220 isolates from 114 patients were analyzed and 118 different patient isolates examined for the presence of the virulence factors cagA, vacA, dupA, their phylogenetic origin and their resistance against the commonly used antibiotics amoxicillin, clarithromycin, metronidazole and tetracycline. We report that H. pylori isolates from Nigeria and South Africa differ significantly in their phylogenetic profiles and in their expression of virulence factors. VacA mosaicism is intensive, resulting in m1-m2 vacA chimeras and frequent s1m1 and s1m2 vacA subtypes in hpAfrica2 strains. Gastric lesions were diagnosed more frequent in Nigerian versus South African patients and H. pylori isolates that are resistant against one or multiple antibiotics occur frequently in both countries.

Guidelines for endoscopic diagnosis of early gastric cancer

The Japan Gastroenterological Endoscopy Society developed the Guideline for Endoscopic Diagnosis of Early Gastric Cancer based on scientific methods. Endoscopy for the diagnosis of early gastric cancer has been acknowledged as a useful and highly precise examination, and its use has become increasingly more common in recent years. However, the level of evidence in this field is low, and it is often necessary to determine recommendations based on expert consensus only. This clinical practice guideline consists of the following sections to provide the current guideline: [I] Risk stratification of gastric cancer before endoscopic examination, [II] Detection of early gastric cancer, [III] Qualitative diagnosis of early gastric cancer, [IV] Diagnosis to choose the therapeutic strategy for gastric cancer, [V] Risk stratification after endoscopic examination, and [VI] Surveillance of early gastric cancer.

Differential Metabolic Alterations and Biomarkers Between Gastric Cancer and Colorectal Cancer: A Systematic Review and Meta-Analysis

Purpose

Numerous metabolomics studies have been conducted to detect the metabolic mechanisms and biomarkers related to gastric cancer and colorectal cancer. Because of the common metabolic features between gastric cancer and colorectal cancer, a differential diagnosis is difficult. Here, we performed a systematic review and meta-analysis to identify differential metabolic biomarkers between these two types of cancers.

Materials and Methods

PubMed, Embase, and ScienceDirect were searched to identify all metabolomics studies of gastric cancer and colorectal cancer published up to September 2018. Differential metabolites or altered pathways were extracted. The intersections and differences for these metabolites and pathways between gastric cancer and colorectal cancer were compared. Candidate biomarker sets for diagnosis were proposed from biofluid or feces by comparing them with tumor tissues.

Results

Totally, 24 and 65 studies were included in gastric cancer and colorectal cancer, and 223 and 472 differential metabolites were extracted, respectively. Eight pathways were reproducibly enriched in blood, tissue and urine in gastric cancer, while, 11 pathways were reproducibly enriched in blood, urine, feces and tissue in colorectal cancer. Candidate metabolic biomarker sets in blood, urine, or feces for these two cancers were proposed. We found 27 pathways (categorized into eight classifications) common to both cancers, five pathways involving 35 metabolites enriched only in gastric cancer, and eight pathways involving 54 metabolites enriched only in colorectal cancer.

Conclusion

The altered metabolic pathways showed signatures of abnormal metabolism in gastric cancer and colorectal cancer; the potential metabolic biomarkers proposed in this study have important implications for the prospective validation of gastric cancer and colorectal cancer.

Helicobacter pylori seroprevalence in six different ethnic groups living in Amsterdam: The HELIUS study

BACKGROUND

Helicobacter pylori prevalence varies greatly worldwide. We explored the prevalence of H. pylori and CagA seropositivity among adults aged 18-44 years living in the Netherlands by ethnicity and migration status (first vs second generation).

MATERIALS AND METHODS

Participants from six different ethnic groups were selected from the population-based multi-ethnic HELIUS study in Amsterdam, the Netherlands. Serum samples were tested for H. pylori antigens using a validated Luminex-based multiplex serology assay. Prevalence ratios were estimated using Poisson regression analysis.

RESULTS

A total of 4683 participants aged 18-44 years were randomly selected based on sex, ethnicity, and age. H. pylori seroprevalence was highest in the Ghanaian group (84%), followed by Moroccan (81%), Turkish (66%), African Surinamese (51%), South-Asian Surinamese (48%), and Dutch (17%) participants. All ethnic minority groups had a significantly higher risk of being H. pylori seropositive compared to the Dutch group. This association was strongest among participants born outside the Netherlands (first generation), but was still significant and apparent among second-generation participants. Among first-generation participants, all groups, except the Moroccans, had a significantly higher proportion of individuals with a cagA + H. pylori strain compared to the Dutch participants.

CONCLUSION

Helicobacter pylori seroprevalence among first-generation migrants is high in the Netherlands and remains elevated among second-generation migrants (ie, those born in the Netherlands). High exposure to H. pylori, and especially to the more virulent cagA+ strain, highlights the need for tailored prevention of gastric diseases (notably peptic ulcers and cancers) among migrants.

[General and particular issues of etiopathogenesis of peptic ulcer and gastric cancer: current status of the problem]

The development of peptic ulcer (PU) and gastric cancer (GC) is the result of the interaction of various internal and external factors. Moreover, if the role ofHelicobacter pylori(H. pylori) in the development of diseases of the stomach is fully established, the significance of many other factors continues to be discussed. Serious controversy is caused by the participation of various strains ofH. pyloriin the development of PU and GC. First of all, these are Vac- and Cag-positive strains ofH. pylori. The role of genetic human polymorphism in the development of this pathology is debatable. Especially the interleukin genes and necrotizing tumor factor alpha. The role of environmental factors in the formation of PU and GC is not fully understood. So, the role of alcohol, occupational hazards and drugs in the development of these diseases continues to be discussed. Further study of risk factors for various diseases of the stomach will optimize their prevention and treatment. The review presents a modern view of individual issues in the pathogenesis of PU and GC.

Effects of Helicobacter pylori on the glutathione-related pathway in gastric epithelial cells

Virulence factors of Helicobacter pylori (H. pylori) are diverse, so various biological responses happen in a host infected with H. pylori. The aim of this study is to conduct the metabolomics-based evaluation on H. pylori infection. AGS human gastric carcinoma cells were infected with H. pylori strain 26695, and then the altered metabolite pathways in the infected AGS cells were analyzed by metabolomics. Metabolites related to the glutathione (GSH) cycle were downregulated by H. pylori infection. Next, we evaluated the effects of H. pylori on the GSH-related pathway in AGS cells infected with H. pylori isolated from patients with atrophic gastritis (AG), duodenal ulcer (DU) and gastric cancer (GC). We found that the declined degree of GSH levels and oxidative stress were greater in AGS cells infected with GC strains than DU and AG-derived strains. There were no significant differences in almost mRNA expressions of GSH-related factors among different clinical strains, but the protein expression of glutathione synthetase was lower in AGS cells infected with GC-derived strains than DU and AG-derived strains. Our data demonstrates that GC-derived H. pylori-induced oxidative stress in a host is stronger and GC-derived strains may have suppressive influences on the host's GSH-related defense systems.

Gastric mucosal microbiota in a Mongolian population with gastric cancer and precursor conditions

BACKGROUND

Incidence and mortality of gastric cancer (GC) are high in Mongolia despite Helicobacter pylori in the Mongolian population being less virulent.

AIM

To evaluate gastric bacterial microbiota profiles in patients with GC and its precursor histological conditions.

METHODS

We conducted a case-control study among 48 GC and 120 noncancer patients (20 normal gastric mucosa [control], 20 gastritis, 40 with atrophy and 40 intestinal metaplasia [IM]). We performed 16S rRNA gene amplicon sequencing and compared taxonomic and functional prediction profiles based on the diagnosis group and H pylori infection status.

RESULTS

The highest overall bacterial alpha diversity metrics were observed in the control group, followed by the IM and cancer groups. The gastritis and atrophy groups had the least diversity. Lactobacilli and Enterococci were the dominant genus in several cancer patients especially in the absence of H pylori. In addition, Carnobacterium, Glutamicibacter, Paeniglutamicibacter, Fusobacterium and Parvimonas were associated with GC regardless of H pylori infection. Firmicutes were decreased in the gastritis and atrophy groups and increased in the IM and cancer groups. The functional metabolic activity of the Embden-Meyerhof-Parnas pathway and the utilization of sugar, were significantly increased in cancer group compared with the noncancer group.

CONCLUSION

Microbial factors other than H pylori may play a role in Mongolian GC. We identified novel associations between GC and the genera Enterococcus, Lactobacillus, Carnobacterium, Glutamicibacter, Paeniglutamicibacter, Fusobacterium, and Parvimonas.

Gastric cancer: genome damaged by bugs

Gastric cancer (GC) is one of the leading causes of cancer-related death worldwide. The role of the microorganisms in gastric tumorigenesis attracts much attention in recent years. These microorganisms include bacteria, virus, and fungi. Among them, Helicobacter pylori (H. pylori) infection is by far the most important risk factor for GC development, with special reference to the early-onset cases. H. pylori targets multiple cellular components by utilizing various virulence factors to modulate the host proliferation, apoptosis, migration, and inflammatory response. Epstein–Barr virus (EBV) serves as another major risk factor in gastric carcinogenesis. The virus protein, EBER noncoding RNA, and EBV miRNAs contribute to the tumorigenesis by modulating host genome methylation and gene expression. In this review, we summarized the related reports about the colonized microorganism in the stomach and discussed their specific roles in gastric tumorigenesis. Meanwhile, we highlighted the therapeutic significance of eradicating the microorganisms in GC treatment.

Hellenic consensus on Helicobacter pylori infection

The Hellenic Society of Gastroenterology recently organized the "Hellenic consensus on Helicobacter pylori (H. pylori) infection". The aim of this publication is to report the guidelines in order to aid the national gastroenterology community in the management of H. pylori infection. Forty-one delegates from all Greek regions, including gastroenterologists, pathologists, clinical microbiologists, epidemiologists and basic scientists, were invited to this meeting. The participants were allocated to 1 of the 4 main topics of the meeting: i.e., H. pylori diagnosis and association with diseases; H. pylori and gastric cancer; H. pylori and extragastric associated disorders; and H. pylori treatment. The results of each subgroup were submitted to a final consensus vote that included all participants. Relevant data based on international and Greek publications were presented, and the quality of evidence, strength of recommendation, and level of consensus were graded. The cutoff level of 70% was considered as acceptance for the final statement. It is hoped that the recommendations and conclusions of this report will guide Greek doctors in their daily practice concerning the management of H. pylori infection.

Molecular anatomy and pathogenic actions of Helicobacter pylori CagA that underpin gastric carcinogenesis

Chronic infection with Helicobacter pylori cagA-positive strains is the strongest risk factor for gastric cancer. The cagA gene product, CagA, is delivered into gastric epithelial cells via the bacterial type IV secretion system. Delivered CagA then undergoes tyrosine phosphorylation at the Glu-Pro-Ile-Tyr-Ala (EPIYA) motifs in its C-terminal region and acts as an oncogenic scaffold protein that physically interacts with multiple host signaling proteins in both tyrosine phosphorylation-dependent and -independent manners. Analysis of CagA using in vitro cultured gastric epithelial cells has indicated that the nonphysiological scaffolding actions of CagA cell-autonomously promote the malignant transformation of the cells by endowing the cells with multiple phenotypic cancer hallmarks: sustained proliferation, evasion of growth suppressors, invasiveness, resistance to cell death, and genomic instability. Transgenic expression of CagA in mice leads to in vivo oncogenic action of CagA without any overt inflammation. The in vivo oncogenic activity of CagA is further potentiated in the presence of chronic inflammation. Since Helicobacter pylori infection triggers a proinflammatory response in host cells, a feedforward stimulation loop that augments the oncogenic actions of CagA and inflammation is created in CagA-injected gastric mucosa. Given that Helicobacter pylori is no longer colonized in established gastric cancer lesions, the multistep nature of gastric cancer development should include a “hit-and-run” process of CagA action. Thus, acquisition of genetic and epigenetic alterations that compensate for CagA-directed cancer hallmarks may be required for completion of the “hit-and-run” process of gastric carcinogenesis.

Helicobacter pylori virulence genes

Helicobacter pylori (H. pylori) is one of the most important human pathogens, infecting approximately half of the global population. Despite its high prevalence, only a subset of H. pylori infected individuals develop serious gastroduodenal pathology. The pathogenesis of H. pylori infection and disease outcome is thus thought to be mediated by an intricate interplay between host, environmental and bacterial virulence factors. H. pylori has adapted to the harsh milieu of the human stomach through possession of various virulence genes that enable survival of the bacteria in the acidic environment, movement towards the gastric epithelium, and attachment to gastric epithelial cells. These virulence factors enable successful colonization of the gastric mucosa and sustain persistent H. pylori infection, causing chronic inflammation and tissue damage, which may eventually lead to the development of peptic ulcers and gastric cancer. Numerous studies have focused on the prevalence and role of putative H. pylori virulence genes in disease pathogenesis. While several virulence factors with various functions have been identified, disease associations appear to be less evident, especially among different study populations. This review presents key findings on the most important H. pylori virulence genes, including several bacterial adhesins and toxins, in children and adults, and focuses on their prevalence, clinical significance and potential relationships.

Prevalence of Helicobacter pylori Infection, Its Virulent Genotypes, and Epstein-Barr Virus in Peruvian Patients With Chronic Gastritis and Gastric Cancer

PURPOSE

Helicobacter pylori (HP) and Epstein Barr virus (EBV) infections induce chronic gastritis (CG) and are accepted carcinogenics of gastric cancer (GC). Our objective for this study was to determine the prevalence of these agents and clinicopathological features of GC and CG associated with the infection.

PATIENTS AND METHODS

A single-center cohort of 375 Peruvian patients with GC and 165 control subjects with CG were analyzed. Evaluation of HP and EBV genes was performed through quantitative polymerase chain reaction.

RESULTS

Prevalence of HP was 62.9% in the whole population and 60.8% in the GC subset. The cagA gene was detected in 79.9%; vacAs1 and vacAm1 alleles in 41.6% and 60.7%, respectively; and concurrent expression of vacAs1 and vacAm1 in 30.4% of infected patients in the whole series. The prevalence of EBV was 14.1% in the whole population and was higher in GC (P < .001). Coinfection of HP and EBV was found in 7.8% and was also higher in GC in univariate (P < .001) and multivariate (P = .011) analyses. Infection rates of HP and EBV were not associated with a geographic location in the whole series. Few clinicopathological features have been associated with infectious status.

CONCLUSION

Prevalence of HP infection and virulent strains are high in the Peruvian population. Infection by EBV was more frequent in patients with GC.

Gastric MALT lymphoma refractory to Helicobacter pylori antibiotic therapy

Gastric mucosa-associated lymphoid tissue lymphoma is a rare clonal B-cell neoplasm that is usually associated with Helicobacter pylori infection. The presence of H. pylori should be confirmed via special stains and/or immunohistochemistry of gastric biopsies from multiple anatomic sites of the stomach. Mucosa-associated lymphoid tissue lymphoma is diagnosed with histopathologic examination and positive immunohistochemical staining for certain B-cell markers. Ancillary testing should be performed to determine any genetic abnormalities in H. pylori that increases its virulence. We report the case of a 49-year-old woman with recurrent epigastric pain and vomiting found to have chronic H. pylori gastritis despite appropriate rounds of treatment with first-line therapy. She was diagnosed with mucosa-associated lymphoid tissue lymphoma via histopathologic examination. She ultimately required oncological treatment due to H. pylori infection refractory to antibiotic treatment.

Prevalence of human papillomavirus and Helicobacter pylori in esophageal and gastroesophageal junction cancer biopsies from a case-control study in Ethiopia

BACKGROUND

Ethiopia lies in the high-risk corridor of esophageal squamous cell carcinoma in East Africa, where individuals with this malignancy often do not report established risk factors, suggesting unidentified etiologies. Here, we report the prevalence of mucosal human papillomavirus (HPV) and of Helicobacter pylori (H. pylori) detection in endoscopy-obtained esophageal and gastroesophageal junction biopsies and in oral cell specimens taken at the time of esophageal cancer diagnosis in a case-control study in Addis Ababa, Ethiopia.

METHODS

DNA extraction was performed from fresh frozen tissue and oral cell pellets obtained with saline solution gargling subsequently fixed with ethanol. Mucosal HPV and H. pylori DNA was detected using highly sensitive assays that combine multiplex polymerase chain reaction and bead-based Luminex technology. The proportions of specimens testing positive were expressed as percentages, with binomial 95% confidence intervals. Agreement of results between tissue biopsy and oral cell specimens was estimated using the kappa statistic. Comparison of study participants' characteristics by test results was done using the Pearson chi-square test.

RESULTS

HPV DNA was detected in 1 of 62 tumor specimens (2, 95% confidence interval (CI): 0-9%), corresponding to HPV16 type. HPV DNA was detected in the oral cavity of 7 cases (11, 95% CI: 5-22%) and 4 of 56 matched healthy controls (7, 95% CI: 2-17%), with multiple HPV types detected. Detection of H. pylori DNA was 55% (95% CI: 42-68%), and 20 of 34 H. pylori-positive specimens (59, 95% CI: 41-75%) were positive for the cagA gene. Agreement of detection rates between tissue and oral cells in cases was poor for HPV and for H. pylori.

CONCLUSIONS

The prevalence of mucosal-type HPV was very low, whereas H. pylori was more commonly detected, with a high proportion testing positive for the pro-inflammatory gene cagA. These novel findings remain to be replicated in larger studies and with the addition of serological determinations to better understand their biological significance in the context of esophageal and gastroesophageal junction cancers.

Inverse association of Helicobacter pylori cagPAI genotypes with risk of cardia and non-cardia gastric adenocarcinoma

Iran is a high-risk country for cardia gastric adenocarcinoma (CGA) in Central Asia, with an incidence rate five times the average global rate, and shows a high infection rate for Helicobacter pylori (69%). The aim was to examine the associations of multiple H. pylori cagPAI genotypes (ie cagH, cagL, cagG, and orf17) with the risk of CGA, non-CGA, and different histological types of GA in Iran. A large number of H. pylori strains (N = 336) were successfully cultured and genotyped. Histopathological evaluations were performed. The analysis showed an inverse association between the cagH+ genotype and the risk of CGA and intestinal-type gastric adenocarcinoma (IGA) (adjusted ORs; 0.312 and 0.283, respectively), where the controls were nontumors. The orf17+ genotype decreased the risk of non-CGA and diffuse-type gastric adenocarcinoma (DGA)(adjusted ORs; 0.310 and 0.356, respectively). When the controls were those with nonatrophic gastritis, the cagG+ genotype was negatively associated with the risk of CGA, non-CGA, IGA, and DGA (adjusted ORs; 0.324, 0.366, 0.306, and 0.303, respectively). We did not find such a significant association for the cagL+ genotype in multiple logistic regression analysis. Combination of the vacA c2 and cagPAI genotypes further decreased the risk estimates for GAs. This study showed the reverse association of H. pylori cagPAI genotypes-cagH+ and cagG+ -with the risk of CGA in male patients aged ≥ 55 in Iran. Presence of the vacA c2 genotype in combination with cagPAI genotypes showed strong inverse associations with the risk of CGA and non-CGA. These findings may reveal a coordinated relationship between the vacA c2 and cagPAI genotypes.

Human Lung Microbiome on the Way to Cancer

Recent research on cancer-associated microbial communities led to the accumulation of data on the interplay between bacteria, immune and tumor cells, the pathways of bacterial induction of carcinogenesis, and its meaningfulness for medicine. Microbial communities that have any kind of impact on tumor progression and microorganisms associated with tumors have been defined as oncobiome. Over the last decades, a number of studies were dedicated to Helicobacter pylori and its role in the progression of stomach tumors, so this correlation can be regarded as proven. Involvement of bacteria in the induction of lung cancer has been largely ignored for a long time, though some correlations between this type of cancer and lung microbiome were established. Despite the fact that in the present the microbial impact on lung cancer progression has many confirmations, the underlying mechanisms are poorly understood. Microorganisms can contribute to tumor initiation and progression through production of bacteriotoxins and other proinflammatory factors. The purpose of this review is to organize the available data on lung cancer microbiome and its role in malignant tumor progression.

Differences in Helicobacter pylori and CagA antibody changes after eradication between subjects developing and not developing gastric cancer

We evaluated serological Helicobacter pylori and cytotoxin-associated gene A (CagA) antibodies and endoscopic atrophy after eradication to identify factors predicting post-eradication gastric cancer development. Thirty-five patients with successful eradiation were divided into the post-eradication gastric cancer (13 cases) and non-gastric cancer (22 cases) groups. Serum Helicobacter pylori and CagA antibody titers and endoscopic atrophy before and six years after eradication were examined. Median Helicobacter pylori antibody titers had decreased significantly from baseline at 0.5–2 years after eradication in both groups (gastric cancer group, from 39.0 to 11.0 U/ml, p = 0.011; non-gastric cancer group, from 29.6 to 4.97 U/ml, p<0.001), but were significantly higher in the gastric cancer than in the non-gastric cancer group (p = 0.029). Median serum CagA antibody titers had also decreased significantly at 0.5–2 years after eradication (gastric cancer group, from 6.35 to 3.23 U/ml, p = 0.028; non-gastric cancer group, from 9.88 to 1.21 U/ml, p = 0.0045). Serum CagA in each group showed no significance. Endoscopic atrophy improved significantly after eradication in the non-gastric cancer, but not the gastric cancer, group (p = 0.0007). In conclusion, changes in Helicobacter pylori and CagA antibody titers and endoscopic atrophy after eradication might be useful as predictive factors for post-eradication gastric cancer.

Western-Type Helicobacter pylori CagA are the Most Frequent Type in Mongolian Patients

Helicobacter pylori infection possessing East-Asian-type CagA is associated with carcinogenesis. Mongolia has the highest mortality rate from gastric cancer. Therefore, we evaluated the CagA status in the Mongolian population. High risk and gastric cancer patients were determined using endoscopy and histological examination. H. pylori strains were isolated from different locations in Mongolia. The CagA subtypes (East-Asian-type or Western-type, based on sequencing of Glu-Pro-Ile-Tyr-Ala (EPIYA) segments) and vacA genotypes (s and m regions) were determined using PCR-based sequencing and PCR, respectively. In total, 368 patients were examined (341 gastritis, 10 peptic ulcer, and 17 gastric cancer). Sixty-two (16.8%) strains were cagA-negative and 306 (83.1%) were cagA-positive (293 Western-type, 12 East-Asian-type, and one hybrid type). All cagA-negative strains were isolated from gastritis patients. In the gastritis group, 78.6% (268/341) had Western-type CagA, 2.9% (10/341) had East-Asian-type, and 18.2% (61/341) were cagA-negative. However, all H. pylori from gastric cancer patients possessed Western-type CagA. Histological analyses showed that East-Asian-type CagA was the most virulent strains, followed by Western-type and cagA-negative strains. This finding agreed with the current consensus. CagA-positive strains were the most virulent type. However, the fact that different CagA types can explain the high incidence of gastric cancer might be inapplicable in Mongolia.

Role of a Stem-Loop Structure in Helicobacter pylori cagA Transcript Stability

Helicobacter pylori CagA is a secreted effector protein that contributes to gastric carcinogenesis. Previous studies showed that there is variation among H. pylori strains in the steady-state levels of CagA and that a strain-specific motif downstream of the cagA transcriptional start site (the +59 motif) is associated with both high levels of CagA and premalignant gastric histology. The cagA 5' untranslated region contains a predicted stem-loop-forming structure adjacent to the +59 motif. In the current study, we investigated the effect of the +59 motif and the adjacent stem-loop on cagA transcript levels and cagA mRNA stability. Using site-directed mutagenesis, we found that mutations predicted to disrupt the stem-loop structure resulted in decreased steady-state levels of both the cagA transcript and the CagA protein. Additionally, these mutations resulted in a decreased cagA mRNA half-life. Mutagenesis of the +59 motif without altering the stem-loop structure resulted in reduced steady-state cagA transcript and CagA protein levels but did not affect cagA transcript stability. cagA transcript stability was not affected by increased sodium chloride concentrations, an environmental factor known to augment cagA transcript levels and CagA protein levels. These results indicate that both a predicted stem-loop structure and a strain-specific +59 motif in the cagA 5' untranslated region influence the levels of cagA expression.

VacA promotes CagA accumulation in gastric epithelial cells during Helicobacter pylori infection

Helicobacter pylori (H. pylori) is the causative agent of gastric cancer, making it the only bacterium to be recognized as a Class I carcinogen by the World Health Organization. The virulence factor cytotoxin associated gene A (CagA) is a known oncoprotein that contributes to the development of gastric cancer. The other major virulence factor vacuolating cytotoxin A (VacA), disrupts endolysosomal vesicular trafficking and impairs the autophagy pathway. Studies indicate that there is a functional interplay between these virulence factors by unknown mechanisms. We show that in the absence of VacA, both host-cell autophagy and the proteasome degrade CagA during infection with H. pylori. In the presence of VacA, CagA accumulates in gastric epithelial cells. However, VacA does not affect proteasome function during infection with H. pylori suggesting that VacA−disrupted autophagy is the predominant means by which CagA accumulates. Our studies support a model where in the presence of VacA, CagA accumulates in dysfunctional autophagosomes providing a possible explanation for the functional interplay of VacA and CagA.

Genetic Polymorphisms in Inflammatory and Other Regulators in Gastric Cancer: Risks and Clinical Consequences

Helicobacter pylori infection is associated with the development of a chronic inflammatory response, which may induce peptic ulcers, gastric cancer (GC), and mucosa-associated lymphoid tissue (MALT) lymphoma. Chronic H. pylori infection promotes the genetic instability of gastric epithelial cells and interferes with the DNA repair systems in host cells. Colonization of the stomach with H. pylori is an important cause of non-cardia GC and gastric MALT lymphoma. The reduction of GC development in patients who underwent anti-H. pylori eradication schemes has also been well described. Individual susceptibility to GC development depends on the host's genetic predisposition, H. pylori virulence factors, environmental conditions, and geographical determinants. Biological determinants are urgently sought to predict the clinical course of infection in individuals with confirmed H. pylori infection. Possible candidates for such biomarkers include genetic aberrations such as single-nucleotide polymorphisms (SNPs) found in various cytokines/growth factors (e.g., IL-1β, IL-2, IL-6, IL-8, IL-10, IL-13, IL-17A/B, IFN-γ, TNF, TGF-β) and their receptors (IL-RN, TGFR), innate immunity receptors (TLR2, TLR4, CD14, NOD1, NOD2), enzymes involved in signal transduction cascades (PLCE1, PKLR, PRKAA1) as well as glycoproteins (MUC1, PSCA), and DNA repair enzymes (ERCC2, XRCC1, XRCC3). Bacterial determinants related to GC development include infection with CagA-positive (particularly with a high number of EPIYA-C phosphorylation motifs) and VacA-positive isolates (in particular s1/m1 allele strains). The combined genotyping of bacterial and host determinants suggests that the accumulation of polymorphisms favoring host and bacterial features increases the risk for precancerous and cancerous lesions in patients.

Diagnostic methods for Helicobacter pylori infection: ideals, options, and limitations

Helicobacter pylori (H. pylori) resides in the stomach, colonizes gastric epithelium, and causes several digestive system diseases. Several diagnostic methods utilizing invasive or non-invasive techniques with varying levels of sensitivity and specificity are developed to detect H. pylori infection. Selection of one or more diagnostic tests will depend on the clinical conditions, the experience of the clinician, cost, sensitivity, and specificity. Invasive methods require endoscopy with biopsies of gastric tissues for the histology, culture, and rapid urease test. Among non-invasive tests, urea breath test and fecal antigen tests are a quick diagnostic procedure with comparable accuracy to biopsy-based techniques and are methods of choice in the test and treatment setting. Other techniques such as serological methods to detect immunoglobulin G antibodies to H. pylori can show high accuracy as other non-invasive and invasive biopsies, but do not differentiate between current or past H. pylori infections. Polymerase chain reaction (PCR) is an emerging option that can be categorized as invasive and non-invasive tests. PCR method is beneficial to detect H. pylori from gastric biopsies without the need for the cultures. There is no other chronic gastrointestinal infection such as H. pylori with a set of comparable diagnostic methodologies. Despite the availability of multiple diagnostic methods, it remains unclear on the choice of any one method as the gold standard for detecting H. pylori infection, especially in epidemiological studies. In this work, we review the principal diagnostic methods used to detect H. pylori infection and their advantages and disadvantages, and applications in clinical practice.

Epidemiology of gastric cancer and risk factors

Gastric cancer is, still nowadays, an important healthcare problem worldwide. In Italy, it represents the fifth tumour by frequency in both men and women over 70 years old. A crucial point is represented by the percentage of early gastric cancers usually found, which is actually very low, and it carries to a worse morbidity and mortality. The most important focus in this oncological disease, is to perform an effective detection of the most common precancerous lesion linked with this neoplasia, chronic atrophic gastritis, in order to avoid the future outcome of gastric cancer itself.

CagA increases DNA methylation and decreases PTEN expression in human gastric cancer

Gastric cancer is one of the leading causes of cancer-associated mortality worldwide. Cytotoxin-associated gene A (CagA) has been reported to be associated with gastric diseases. Phosphatase and tensin homolog (PTEN) and tet methylcytosine dioxygenase 1 (Tet1) are important tumor-suppressor genes. The present study aimed to investigate the underlying functions of CagA in human gastric cancer, and to explore the associations between CagA, PTEN and Tet1 in gastric cancer. For that purpose, CagA overexpression and Tet1 interference recombinant lentiviral plasmids were constructed. Quantitative polymerase chain reaction (qPCR) was utilized to screen gene expression in HGC-27 human gastric cancer cells overexpressing CagA. qPCR and western blotting were used to detect gene and protein expression, respectively. In addition, the methylation status of PTEN was detected by methylation-specific PCR. The expression levels of PTEN, Tet1, apolipoprotein B mRNA editing enzyme catalytic subunit (APOBEC)3A, APOBEC3C and APOBEC3F were significantly decreased in the CagA overexpression group compared with in the negative control group in HGC-27 cells. Compared with in the negative control group, the mRNA and protein expression levels of PTEN were markedly decreased in cells with Tet1 interference. The decreased expression of PTEN was associated with increased methylation levels in the cells. In addition, the protein expression levels of PTEN were significantly decreased in HGC-27 cells when CagA was overexpressed. The expression levels of PTEN and Tet1 were also markedly decreased in CagA⁺ gastric cancer tissues compared with in non-cancerous tissues. The decreased expression of PTEN in CagA⁺ gastric cancer tissues was associated with increased methylation levels. In conclusion, overexpression of CagA significantly decreased the expression of PTEN, Tet1, APOBEC3A, APOBEC3C and APOBEC3F in human gastric cancer. In addition, CagA increased DNA methylation and decreased PTEN expression, which was reversed by Tet1 overexpression. The present study may facilitate future therapeutic approaches targeting human gastric cancer.

Helicobacter pylori outer membrane vesicles involvement in the infection development and Helicobacter pylori-related diseases

Helicobacter pylori - (H. pylori) play a role in the pathogenesis of gastritis, gastric and duodenal ulcers as well as gastric cancer. A possible involvement of outer membrane vesicles (OMVs) produced by H. pylori in the distribution of bacterial antigens through the gastric epithelial barrier and their role in the development of local and systemic host inflammatory and immune responses has been suggested. OMVs contain various biologically active compounds, which internalize into host cells affecting signaling pathways and promoting apoptosis of gastric epithelial and immunocompetent cells. OMVs-associated H. pylori virulence factors may strengthen or downregulate the immune responses leading to disease development. This review describes the biological importance of H. pylori OMVs and their role in the course of H. pylori infections, as well as H. pylori related local and systemic effects.

When Is Enough, Enough? When Are More Observational Epidemiologic Studies Needed to Resolve a Research Question: Illustrations Using Biomarker-Cancer Associations

BACKGROUND

Research reproducibility is vital for translation of epidemiologic findings. However, repeated studies of the same question may be undertaken without enhancing existing knowledge. To identify settings in which additional research is or is not warranted, we adapted research synthesis metrics to determine number of additional observational studies needed to change the inference from an existing meta-analysis.

METHODS

The fail-safe number (FSN) estimates number of additional studies of average weight and null effect needed to drive a statistically significant meta-analysis to null (P ≥ 0.05). We used conditional power to determine number of additional studies of average weight and equivalent heterogeneity to achieve 80% power in an updated meta-analysis to detect the observed summary estimate as statistically significant. We applied these metrics to a curated set of 98 meta-analyses on biomarkers and cancer risk.

RESULTS

Both metrics were influenced by number of studies, heterogeneity, and summary estimate size in the existing meta-analysis. For the meta-analysis on Helicobacter pylori and gastric cancer with 15 studies [OR = 2.29; 95% confidence interval (CI), 1.71-3.05], FSN was 805 studies, supporting futility of further study. For the meta-analysis on dehydroepiandrosterone sulfate and prostate cancer with 7 studies (OR = 1.29; 95% CI, 0.99-1.69), 5 more studies would be needed for 80% power, suggesting further study could change inferences.

CONCLUSIONS

Along with traditional assessments, these metrics could be used by stakeholders to decide whether additional studies addressing the same question are needed.

IMPACT

Systematic application of these metrics could lead to more judicious use of resources and acceleration from discovery to population-health impact.

Zinc Oxide Tetrapods Based Biohybrid Interface for Voltammetric Sensing of Helicobacter pylori

Helicobacter pylori is a Gram-negative, spiral shaped, microaerophilic bacteria that colonizes human gastric mucosa and causes various gastric diseases. In this work, the utilization of ion irradiated zinc oxide tetrapods (ZnO-T) based biohybrid interface accentuates the development of an electrochemical immunosensor for the fast and sensitive detection of H. pylori. After coating of (ZnO-T) over the surface of screen printed electrode (SP-AuE) through electrodeposition, the ZnO-T/SP-AuE was irradiated with N₂⁺ ion of energy 100 keV. The ion irradiation significantly enhances the conductivity of ZnO-T coated SP-AuE. The revamped SP-AuE is further used for establishing an immunosensor interface based upon immobilization of the CagA antigen on ZnO-T electrodeposited over the surface of SP-AuE. The sensing interface demonstrated good linearity (0.2 ng/mL to 50 ng/mL) and limit of detection (0.2 ng/mL). The ion beam irradiated ZnO-T based immunosensor showed significantly high conductivity and enhanced the analytical properties of the working electrode in terms of the sensitivity, detection limit, and response time. A study on the comparison of irradiated and pristine electrode is performed for amperometric sensing of H. pylori. In addition, the significance of work conducted on ion irradiated ZnO-T based interfaces provides a basis of further development of electrochemical immunosensors.

The impacts of H. pylori virulence factors on the development of gastroduodenal diseases

Although most H. pylori infectors are asymptomatic, some may develop serious disease, such as gastric adenocarcinoma, gastric high-grade B cell lymphoma and peptic ulcer disease. Epidemiological and basic studies have provided evidence that infection with H. pylori carrying specific virulence factors can lead to more severe outcome. The virulence factors that are associated with gastric adenocarcinoma development include the presence, expression intensity and types of cytotoxin-associated gene A (CagA, especially EPIYA-D type and multiple copies of EPIYA-C) and type IV secretion system (CagL polymorphism) responsible for its translocation into the host cells, the genotypes of vacuolating cytotoxin A (vacA, s1/i1/m1 type), and expression intensity of blood group antigen binding adhesin (BabA, low-producer or chimeric with BabB). The presence of CagA is also related to gastric high-grade B cell lymphoma occurrence. Peptic ulcer disease is closely associated with cagA-genopositive, vacA s1/m1 genotype, babA2-genopositive (encodes BabA protein), presence of duodenal ulcer promoting gene cluster (dupA cluster) and induced by contact with epithelium gene A1 (iceA1), and expression status of outer inflammatory protein (OipA). The prevalence of these virulence factors is diverse among H. pylori isolated from different geographic areas and ethnic groups, which may explain the differences in disease incidences. For example, in East Asia where gastric cancer incidence is highest worldwide, almost all H. pylori isolates were cagA genopositive, vacA s1/i1/m1 and BabA-expressing. Therefore, selection of appropriate virulence markers and testing methods are important when using them to determine risk of diseases. This review summarizes the evidences of H. pylori virulence factors in relation with gastroduodenal diseases and discusses the geographic differences and appropriate methods of analyzing these virulence markers.

Long-term outcome of group D patients with negative serum anti-Helicobacter pylori antibody and positive serum pepsinogen test in healthy Koreans

OBJECTIVE

The aim of this study was to assess the clinical characteristics and long-term outcomes of group D patients (negative H. pylori antibodies and positive pepsinogen level).

METHODS

Group D patients were divided into two groups, that is, the limited endoscopic atrophic gastritis (EAG) group with EAG confined to the antrum and angle (C1 and C2) and the advanced EAG group with gastric body-involved EAG (C3 to O3). We compared the progression of precursor lesions and the occurrence of gastric neoplasms between the two groups.

RESULTS

Among 107 group D patients, the advanced EAG group (n = 60) was elder and had a lower pepsinogen I level and a lower pepsinogen I to II ratio (PGI/II) than the limited EAG group (n = 47). Among the 52 patients who underwent a follow-up endoscopy, three gastric neoplasms were detected (one in the limited and two in the advanced EAG groups). During a median follow-up of 44 months, 10 (43.5%) patients in the limited and 13 (52.0%) in the advanced EAG groups showed EAG progression or newly occurred intestinal metaplasia. A family history of GC (odds ratio [OR] 44.974, 95% confidence interval [CI] 1.360-1487.087), a lower PGI/II (OR 0.247, 95% CI 0.085-0.717) and a longer follow-up duration (OR 1.832, 95% CI 1.200-2.796) increased the risk of progression.

CONCLUSION

A family history of GC and low baseline PGI/II were independently associated with an increased risk of progression of precursor lesions of GC.

Exploring Spatial Trends and Influencing Factors for Gastric Cancer Based on Bayesian Statistics: A Case Study of Shanxi, China

Gastric cancer (GC) is the fourth most common type of cancer and the second leading cause of cancer-related deaths worldwide. To detect the spatial trends of GC risk based on hospital-diagnosed patients, this study presented a selection probability model and integrated it into the Bayesian spatial statistical model. Then, the spatial pattern of GC risk in Shanxi Province in north central China was estimated. In addition, factors influencing GC were investigated mainly using the Bayesian Lasso model. The spatial variability of GC risk in Shanxi has the conspicuous feature of being 'high in the south and low in the north'. The highest GC relative risk was 1.291 (95% highest posterior density: 0.789⁻4.002). The univariable analysis and Bayesian Lasso regression results showed that a diverse dietary structure and increased consumption of beef and cow milk were significantly (p ≤ 0.08) and in high probability (greater than 68%) negatively associated with GC risk. Pork production per capita has a positive correlation with GC risk. Moreover, four geographic factors, namely, temperature, terrain, vegetation cover, and precipitation, showed significant (p < 0.05) associations with GC risk based on univariable analysis, and associated with GC risks in high probability (greater than 60%) inferred from Bayesian Lasso regression model.

Global estimate of gastric cancer in Helicobacter pylori-infected population: A systematic review and meta-analysis

There is information regarding the rates of gastric cancer (GC) in different populations and the important role of Helicobacter pylori in GC development; however, no comprehensive study has yet been performed to investigate the prevalence of GC in H. pylori-infected patients. PubMed, Embase, and Cochrane Library through January 1, 2000 were searched without language restrictions. Quality of included studies was assessed with a critical appraisal checklist recommended by the Joanna Briggs Institute. All of the analyses were conducted using Comprehensive Meta-Analysis Software Version 2.0 and Stata 14.0. Forty-four studies from 17 countries were included. The pooled frequency of GC was 17.4% (95% confidence interval: 16.4-18.5) in H. pylori-infected population. The frequency of GC among H. pylori-infected population varied markedly across countries. The highest rate of GC was observed in H. pylori-infected individuals from Asian countries. The frequency of GC was relatively high in H. pylori-infected population in the world. However, the eradication of H. pylori might be a promising strategy for GC prevention, especially in high-risk populations such as Asian countries.

Helicobacter pylori associated factors in the development of gastric cancer with special reference to the early-onset subtype

Nowadays, gastric cancer is one of the most common neoplasms and the fourth cause of cancer-related death on the world. Regarding the age at the diagnosis it is divided into early-onset gastric carcinoma (45 years or younger) and conventional gastric cancer (older than 45). Gastric carcinomas are rarely observed in young population and rely mostly on genetic factors, therefore provide the unique model to study genetic and environmental alternations. The latest research on early-onset gastric cancer are trying to explain molecular and genetic basis, because young patients are less exposed to environmental factors predisposing to cancer. In the general population, Helicobacter pylori, has been particularly associated with intestinal subtype of gastric cancers. The significant association of Helicobacter pylori infection in young patients with gastric cancers suggests that the bacterium has an etiologic role in both diffuse and intestinal subtypes of early-onset gastric cancers. In this paper we would like to ascertain the possible role of Helicobacter pylori infection in the development of gastric carcinoma in young patients. The review summarizes recent literature on early-onset gastric cancers with special reference to Helicobacter pylori infection.

Prevalence of Helicobacter pylori and its CagA subtypes in gastric cancer and duodenal ulcer at an Austrian tertiary referral center over 25 years

Background and aims

The prevalence of Helicobacter pylori (H. pylori) tends to be lower in Western countries such as central Europe compared with Asia. The virulence of H. pylori is influenced by its subtype composition, most importantly by the presence or absence of different types of cytotoxin-associated gene A(CagA). This study aimed to assess the prevalence of H. pylori and its respective CagA phenotype in a large retrospective cohort of patients with gastric cancer or duodenal ulcer at a Western tertiary referral institution.

Methods

H. pylori positive gastric biopsy samples from patients diagnosed with the afore mentioned diseases within the past 25 years were re-evaluated by histology for H. pylori and status of gastritis. Confirmed H. pylori positive cases were processed for immunohistochemistry (IHC) for H. pylori,CagA, and EastAsiantype CagA.

Results

The prevalence of H. pylori positive gastric biopsy samples decreased from 20.7% to 2.3% within the study period. Among the gastric cancer patients, the H. pylori positive rate was 16.6%, and didn’t show significant changes over time (p = 0.38). Contrary, the H. pylori positive rate of duodenal ulcer decreased significantlyfrom 40% to 5% (p = 0.01). Within H. pylori positive groups ofboth diseases, CagA was highly detected at IHC (86% and 78%, respectively). Except for a few patients originating from East Asian countries, all CagA detected in this study were of Western type.

Conclusion

In this first Western investigation on the chronological prevalence of H. pylori and its most relevant subtypes, Western type of CagA was highly detected in two important index diseases of the pathogen. This raises further questions about the virulence of this subtype.