Helicobacter pylori infection and gastric cancer: systematic review of the epidemiological studies

Prognostic impact of deprivation on esophagogastroduodenoscopy outcome

Background and study aims Socioeconomic deprivation has long been associated with many gastrointestinal diseases, yet its influence on esophagogastroduodenoscopy (EGD) diagnosis has not been evaluated. The aim of this study was to investigate the influence of deprivation on outcomes of EGD irrespective of referral reason. Patients and methods Two thousand consecutive patients presenting to four Health Boards in Wales beginning in June 2019 were studied retrospectively with deprivation scores calculated using the Wales Indices of Multiple Deprivation (WIMD). Patients were subclassified into quintiles for analysis (Q1 most, Q5 least deprived). Results Inhabitants of the most deprived areas were more likely to be diagnosed with peptic ulcer (Q1 7.9%, Q5 4.7%; odds ratio [OR] 0.498, P =0.018), severe esophagitis (LA4, Q1 2.7% v Q5 0%, OR 0.089, P 0.002), Helicobacter pylori infection (Q1 5.4%, Q5 1.7%; OR 0.284, P =0.002), but less likely to be diagnosed with Barrett's esophagus (Q1 6.3% v Q5 12.3%, OR 2.146, P =0.004) than those from the least deprived areas. New cancer diagnoses numbered 53 and were proportionately higher after presentation for urgent suspected cancer (USC, n=35, 4.6%) than for routine referrals (n=3, 0.6%, P < 0.001). Deprivation was associated with more advanced stage cancer (stage III Q1 16.7% v Q5 5.6%, OR 0.997, P =0.006: stage IV Q1 16.7% v Q2 38.9% v Q5 22.2%, OR 0.998, P =0.049). Conclusions Deprivation was associated with two-fold more peptic ulcer disease, three-fold more H. pylori infection, and 12-fold more severe esophagitis, and more advanced cancer stage.

CCR6+ T helper cells and regulatory T cells in the blood and gastric mucosa during Helicobacter pylori infection

BACKGROUND

Helicobacter pylori (H. pylori) can evade the host's immune response and persist for a long time on the gastric mucosa. T helper (Th) cells appear to be involved in the control of H. pylori bacteria but promote mucosal inflammation. In contrast, regulatory T cells (Tregs) may reduce inflammation but promote H. pylori persistence. CC motif chemokine receptor 6 (CCR6) is involved in the migration of various cells into inflamed gastric mucosa. In this study, we examined CCR6+ Th cells and CCR6+ Tregs during H. pylori infection in humans.

MATERIALS AND METHODS

Isolation of cells from blood and mucosal biopsies, magnetic separation of В cells, CD4+ and CD4+CCR6+CD45RO+ T cells, antigen-specific activation, B cell response in vitro, flow cytometry, determination of CD4+CD25hiFoxP3+ Tregs and various groups of Th cells.

RESULTS

CD4+CCR6+ blood lymphocytes from healthy donors included Th cells and Tregs. These CCR6+ Th cells produced proinflammatory cytokines and also stimulated plasma cell maturation and antibody production in vitro. H. pylori gastritis and peptic ulcer disease were associated with an increase in the number of circulate CD4+CCR6+CD45RO+ cells and the percentage of Th1, Th17 and Th1/17 cells in this lymphocyte subgroup. In H. pylori-positive patients, circulating CD4+CCR6+ cells contained a higher proportion of H. pylori-specific cells compared with their CD4+CCR6- counterparts. H. pylori infection strongly increased the content of CD4+ lymphocytes in the inflamed gastric mucosa, with the majority of these CD4+ lymphocytes expressing CCR6. CD4+CCR6+ lymphocytes from H. pylori-infected stomach included Tregs and in vivo activated T cells, some of which produced interferon-γ without ex vivo stimulation.

CONCLUSION

H. pylori infection causes an increase in the number of mature CD4+CCR6+ lymphocytes in the blood, with a pro-inflammatory shift in their composition and enrichment of the gastric mucosa with CD4+CCR6+ lymphocytes, including CCR6+ Th1 cells and Tregs.

In Vitro Synergistic Antibacterial and Anti-Inflammatory Effects of Nisin and Lactic Acid in Yogurt against Helicobacter pylori and Human Gastric Cells

Helicobacter pylori is a bacterium that naturally thrives in acidic environments and has the potential to induce various gastrointestinal disorders in humans. The antibiotic therapy utilized for treating H. pylori can lead to undesired side effects, such as dysbiosis in the gut microbiota. The objective of our study was to explore the potential antibacterial effects of nisin and lactic acid (LA) in yogurt against H. pylori. Additionally, we investigated the anti-inflammatory effects of nisin and LA in human gastric (AGS) cells infected with H. pylori. Nisin and LA combination showed the strongest inhibitory activity, with confirmed synergy at 0.375 fractional inhibitory concentration index. Also, post-fermented yogurt with incorporation of nisin exhibited antibacterial effect against H. pylori. The combination of nisin and LA resulted in a significant reduction of mRNA levels of bacterial toxins of H. pylori and pro-inflammatory cytokines in AGS cells infected with H. pylori. Furthermore, this also increased bacterial membrane damage, which led to DNA and protein leakage in H. pylori. Overall, the combination of nisin and LA shows promise as an alternative therapy for H. pylori infection. Additionally, the incorporation of nisin into foods containing LA presents a potential application. Further studies, including animal research, are needed to validate these findings and explore clinical applications.

The global prevalence of gastric cancer in Helicobacter pylori-infected individuals: a systematic review and meta-analysis

BACKGROUND

Helicobacter pylori is a gastrointestinal pathogen that infects around half of the world's population. H. pylori infection is the most severe known risk factor for gastric cancer (GC), which is the second highest cause of cancer-related deaths globally. We conducted a systematic review and meta-analysis to assess the global prevalence of GC in H. pylori-infected individuals.

METHODS

We performed a systematic search of the PubMed, Web of Science, and Embase databases for studies of the prevalence of GC in H. pylori-infected individuals published from 1 January 2011 to 20 April 2021. Metaprop package were used to calculate the pooled prevalence with 95% confidence interval. Random-effects model was applied to estimate the pooled prevalence. We also quantified it with the I2 index. Based on the Higgins classification approach, I2 values above 0.7 were determined as high heterogeneity.

RESULTS

Among 17,438 reports screened, we assessed 1053 full-text articles for eligibility; 149 were included in the final analysis, comprising data from 32 countries. The highest and lowest prevalence was observed in America (pooled prevalence: 18.06%; 95% CI: 16.48 - 19.63; I2: 98.84%) and Africa (pooled prevalence: 9.52%; 95% CI: 5.92 - 13.12; I2: 88.39%). Among individual countries, Japan had the highest pooled prevalence of GC in H. pylori positive patients (Prevalence: 90.90%:95% CI: 83.61-95.14), whereas Sweden had the lowest prevalence (Prevalence: 0.07%; 95% CI: 0.06-0.09). The highest and lowest prevalence was observed in prospective case series (pooled prevalence: 23.13%; 95% CI: 20.41 - 25.85; I2: 97.70%) and retrospective cohort (pooled prevalence: 1.17%; 95% CI: 0.55 - 1.78; I 2: 0.10%).

CONCLUSIONS

H. pylori infection in GC patients varied between regions in this systematic review and meta-analysis. We observed that large amounts of GCs in developed countries are associated with H. pylori. Using these data, regional initiatives can be taken to prevent and eradicate H. pylori worldwide, thus reducing its complications.

TAS2R38 gene in relation to Helicobacter pylori infection and blood groups in different age groups

Of the factors predisposing to gastric cancer is Helicobacter pylori infection affecting more than 50% of the general population. Genetic variation is an established player in certain diseases susceptibility. TAS2R38 gene polymorphisms have been found to influence bitter taste ability to chemicals with malicious characteristics and consequently affect metabolism and disease development. This study aimed to investigate the correlation between TAS2R38 gene polymorphisms and H. pylori seropositivity. The study involved 105 apparently healthy individuals. They were grouped into four groups according to their age and gender; young male, young female, middle-aged male and middle-aged female. All groups were tested for H. pylori serum antibody using screening rapid test. Participants were also tested for tasting PTC for TAS2R38 gene detection by using Bartovation PTC test paper and grouped accordingly into: homozygote (highly bitter taste), heterozygote (slight to moderate bitter taste), or negative gene carrier (no taste at all). ABO and Rhesus- blood grouping was determined by standard serological analysis. Of the 105 patients, 22.85% were tested homozygotes for TAS2R38 gene, 40.95% were heterozygotes and 36.19% were nontasters, no significant difference (p &gt; 0.9). H. pylori seropositivity was encountered in 16.19% of the whole participants, 11.5% of the male participants and 20.75% of the female participants (p &gt; 0.9). No significant difference in seropositivity was monitored among the four age groups (p &gt; 0.3) and the ABO/Rh blood groups (p &gt; 0.9). A lack of significant correlation (r = 0.046) between H. pylori antibody test positivity and tasting PTC (TAS2R38 gene) was reported. Similarly, no association was found between PTC tasting and participants’ ABO blood grouping, age or gender (r = 0.086, 0.083 and 0.029, respectively). Yet, weak negative (reverse) relationship (r = -0.29, p-value = 0.002) was gained between PTC and Rh grouping. No correlation was revealed between TAS2R38 polymorphism and the studied variable; age, gender and blood group indicating the absence of an apparent role of the gene in vulnerability to H. pylori infection. Further studies involving a larger sample size is required to confirm the obtained result.

Risk Factors Analysis and Prediction Model Establishment of Intestinal Metaplasia or Dysplasia in Patients With Chronic Atrophic Gastritis: A Multi-Center Retrospective Study

Objective

To investigate the risk factors and construct a prediction model of chronic atrophic gastritis (CAG) patients with intestinal metaplasia or dysplasia.

Method

The clinical data of 450 patients with CAG who were diagnosed and treated in the Department of Gastroenterology of the Second Affiliated Hospital of Anhui University of Traditional Chinese Medicine from June 2016 to February 2022 were collected. Single and multiple factors logistic regression analysis were used to explore the risk factors of intestinal metaplasia or dysplasia in patients of training cohort. Then, we constructed a model to predict the onset of intestinal metaplasia or dysplasia based on the data of training cohort, following which we tested the model in an external validation cohort of 193 patients from a local university teaching hospital. The ROC curve, calibration curve, and decision curve analysis were used to evaluate the accuracy of the prediction model.

Result

Helicobacter pylori (H. pylori, HP) infection, pepsinogen I, gastrin-17, and the number of lesions were found to be independent rick factors of the model. The liner prediction model showed excellent predictive value in both training cohort and validation cohort.

Conclusion

HP infection, pepsinogen I, gastrin-17, and the number of lesions are independent risk factors for intestinal metaplasia or dysplasia in patients with CAG. The prediction model constructed based on these factors has a high accuracy and excellent calibration, which can provide a great basis for condition assessment and individualized treatment of the patients.

Effectiveness of a surveillance program of upper endoscopy for upper gastrointestinal cancers in Lynch syndrome patients

BACKGROUND AND AIMS

Lynch syndrome (LS) is the most common cause of hereditary colorectal cancer and is associated with an increased lifetime risk of gastric and duodenal cancers of 8-16% and 7%, respectively; therefore, we aim to describe an esophagogastroduodenoscopy (EGD) surveillance program for upper gastrointestinal (GI) precursor lesions and cancer in LS patients.

METHODS

Patients who either had positive genetic testing or met clinical criteria for LS who had a surveillance EGD at our institution from 1996 to 2017 were identified. Patients were included if they had at least two EGDs or an upper GI cancer detected on the first surveillance EGD. EGD and pathology reports were extracted manually.

RESULTS

Our cohort included 247 patients with a mean age of 47.1 years (SD 12.6) at first EGD. Patients had a mean of 3.5 EGDs (range 1-16). Mean duration of follow-up was 5.7 years. Average interval between EGDs was 2.3 years. Surveillance EGD detected precursor lesions in 8 (3.2%) patients, two (0.8%) gastric cancers and two (0.8%) duodenal cancers. Two interval cancers were diagnosed: a duodenal adenocarcinoma was detected 2 years, 8 months after prior EGD and a jejunal adenocarcinoma was detected 1 year, 9 months after prior EGD.

CONCLUSIONS

Our data suggest that surveillance EGD is a useful tool to help detect precancerous and cancerous upper GI lesions in LS patients. To our knowledge, this is the first study to examine a program of surveillance EGDs in LS patients. More data are needed to determine the appropriate surveillance interval.

A Case Control Study of the Seroprevalence of Helicobacter pylori Proteins and Their Association with Pancreatic Cancer Risk

Background: The association between Helicobacter pylori (H. pylori) infection and pancreatic cancer (PC) risk remains inconclusive. We examined the association between H. pylori antibodies and PC risk in a case-control study at a comprehensive cancer center.

Methods: Multiplex serology using a glutathione S-transferase capture immunosorbent assay in conjunction with fluorescent bead technology was used to measure antibodies to 15 H. pylori proteins in serum or plasma from 131 incident cases with PC or a PC precursor and 131 healthy controls. Reactivity to ≥4 H. pylori proteins was defined as the overall seroprevalence. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), with adjustment for age at diagnosis/interview, gender, and race.

Results: The majority of the sample was 50 years or older, and from the white race group. Half of the sample were women. Seroprevalence ≥4 of H. pylori proteins was 11.1%. Overall, H. pylori seroprevalence was not associated with PC risk (OR: 0.59; 95% CI: 0.25–1.40). The prevalence of several H. pylori-specific proteins HP537 (OR: 1.78; 95% CI: 0.30–10.51), HP305 (OR: 1.38; 95% CI: 0.61–3.16), and HP410 (OR: 1.31; 95% CI: 0.44–3.96) increased the odds of PC. Similarly, H. pylori-specific proteins HP522 (OR: 0.25; 95% CI: 0.04–1.66), HyuA (OR: 0.49; 95% CI: 0.21–1.14), and HP1564 (OR: 0.63; 95% CI: 0.27–1.51) decreased the odds of PC. However, these findings were not statistically significant at α = 0.05.

Conclusions: Our findings do not support an association between H. pylori and PC risk. Further evaluation of this lack of association is recommended.

Cytokine Profile of CCR6+ T-Helpers Isolated from the Blood of Patients with Peptic Ulcer Associated with Helicobacter pylori Infection

We previously found that the number of CCR6⁺ T-helpers with the phenotype of effector/effector memory T cells increases in the blood of patients with H. pylori-associated peptic ulcer. The mature phenotype and the expression of the chemokine receptor CCR6, which is involved in migration of lymphocytes to the inflamed mucous membrane of the gastrointestinal tract, suggests that these cells are involved in the immune response observed in this clinical condition. To better understand the pathogenetic role of these cells, it is necessary to study their functional activity, specifically, the production of pro-inflammatory cytokines involved in the pathogenesis of the disease.

The aim of the study was to evaluate changes in the blood level of pro-inflammatory types of mature CCR6⁺ T-helpers in H. pylori-associated peptic ulcer disease.

A global and physical mechanism of gastric cancer formation and progression

Gastric cancer is regarded as a major health issue for human being nowadays. The Helicobacter pylori (H. pylori) infection has been found to accelerate the development of gastritis and gastric cancer. Significant efforts have been made towards the understanding of the biology of gastric cancer on both genetic and epigenetic levels. However the physical mechanism behind the gastric cancer formation is still elusive. In this study, we constructed a model for investigating gastric cancer formation by explored the gastric cancer landscape and the flow flux. We uncovered three stable state attractors on the landscape: normal, gastritis and gastric cancer. The definition of each attractor is based on the biological function and gene expression levels. The global stabilities and the switching processes were quantified through the barrier heights and dominant kinetic paths. To investigate the underlying mechanism of the process from normal through the gastritis to the gastric cancer caused by genetic or epigenetic factors, we simulate the oncogenesis of gastric cancer through changes of several gene regulation strengths and H. pylori infection. The simulated results can illustrate the developmental and metastasis process of gastric cancer. Different H. pylori infection degrees accelerating the process from gastritis to gastric cancer can be quantified. Then we applied global sensitivity analysis, one key gene and four key regulations were found. These results are consist with the experimental results and can be used to design the polygenic anti-cancer agents through multiple key genes or regulations. The landscape approach provides a physical and simple strategy for analyzing gastric cancer in a systematic and quantitative way. It also offers new insight into treatment strategy for gastric cancer by adjusting relevant polygenic genes and regulations.

Helicobacter pylori: Commensal, symbiont or pathogen?

This review considers the data on Helicobacter pylori (H. pylori), which have been accumulated over 40 years since its description as an etiological factor in gastrointestinal diseases. The majority of modern publications are devoted to the study of the pathogenic properties of the microorganism in the development of chronic gastritis, peptic ulcer disease, and gastric cancer, as well as methods for its eradication. However, in recent years, there have been more and more studies which have suggested that H. pylori has a beneficial, or potentially positive, effect on the human body. The authors have attempted to objectively analyze the information accumulated in the literature on H. pylori. Some studies consider it as one of the recently identified human bacterial pathogens, and special attention is paid to the evidence suggesting that it is probably part of the composition of the human microbiome as a commensal (commensal from French to English is a table companion) or even a symbiont. The presented data discussing the presence or absence of the effect of H. pylori on human health suggest that there is an apparent ambiguity of the problem. The re-assessment of the data available on H. pylori infection is important in order to answer the question of whether it is necessary to create a program of mass H. pylori eradication or to apply a more personalized approach to treating patients with H. pylori-associated gastrointestinal diseases and to perform eradication therapy.

H. pylori infection alters repair of DNA double-strand breaks via SNHG17

Chronic infections can lead to carcinogenesis through inflammation-related mechanisms. Chronic infection of the human gastric mucosa with Helicobacter pylori is a well-known risk factor for gastric cancer. However, the mechanisms underlying H. pylori-induced gastric carcinogenesis are incompletely defined. We aimed to screen and clarify the functions of long noncoding RNAs (lncRNAs) that are differentially expressed in H. pylori-related gastric cancer. We found that lncRNA SNHG17 was upregulated by H. pylori infection and markedly increased the levels of double-strand breaks (DSBs). SNHG17 overexpression correlated with poor overall survival in patients with gastric cancer. The recruitment of NONO by overabundant nuclear SNHG17, along with the role of cytoplasmic SNHG17 as a decoy for miR-3909, which regulates Rad51 expression, shifted the DSB repair balance from homologous recombination toward nonhomologous end joining. Notably, during chronic H. pylori infection, SNHG17 knockdown inhibited chromosomal aberrations. Our findings suggest that spatially independent deregulation of the SNHG17/NONO and SNHG17/miR-3909/RING1/Rad51 pathways upon H. pylori infection promotes tumorigenesis in gastric cancer by altering the DNA repair system, which is critical for the maintenance of genomic stability. Upregulation of SNHG17 by H. pylori infection might be an undefined link between cancer and inflammation.

Epigenetic silencing of microRNA-204 by Helicobacter pylori augments the NF-κB signaling pathway in gastric cancer development and progression

Helicobacter pylori infection induces gastric cancer (GC) development through a progressive cascade; however, the roles of the microRNAs that are involved in the cascade and the underlying mechanisms are still unclear. Here, we found that microRNA-204 was suppressed in gastric mucosal cells in response to H.pylori infection and downregulated in GC tissues due to aberrant methylation of the promoter of its host gene, TRPM3. Helicobacter pylori induced a progressive downregulation of microRNA-204 from superficial gastritis to intestinal metaplasia, with an accompanying increment of the methylated levels of CpG sites in the TRPM3 promoter. With the GC cellular models of AGS, MGC-803 or BGC-823, we found that microRNA-204 suppressed the tumor necrosis factor (TNF)-α-induced activation of NF-κB signaling pathways and, in animal models, inhibited tumor growth and metastasis. The conditional supernatant of microRNA-204 overexpression GC cells led to reduced tube formation of human umbilical vein endothelial cells. A target gene for microRNA-204 was BIRC2, and in GC cells, BIRC2 knockdown recapitulated the biological phenotype of microRNA-204 overexpression. BIRC2 overexpression promoted the metastasis of GC cells and rescued the inhibition activities of microRNA-204 on cell migration and the NF-κB signaling pathway. Moreover, lower microRNA-204 and higher BIRC2 expression levels were associated with a poorer prognosis of GC patients. These results demonstrate that epigenetic silencing of microRNA-204 induced by H.pylori infection augments the NF-κB signaling pathway in H.pylori-induced gastritis and GC, potentially providing novel intervention targets for these diseases. MicroRNA-204 was epigenetically down-regulated by H. pylori infection in gastric mucosal cells. It led to enhanced BIRC2 expression level and BIRC2/TNF-a/NF-kB signaling pathway activities, which promoted angiogenesis and metastasis of gastric cancer cells.

Phosphorylated STAT3 expression linked to SOCS3 methylation is associated with proliferative ability of gastric mucosa in patients with early gastric cancer

Gastric cancers (GCs) may develop in the gastric mucosa after elimination of Helicobacter pylori (H. pylori) using eradication therapy. Cytokine signaling is a key mechanism underlying GC development and progression, and STAT3 signaling may serve a central role in gastritis-associated tumorigenesis. In the present study, suppressor of cytokine signaling 3 (SOCS3) methylation was examined, as an activator of phosphorylated (p-)STAT3 expression in the non-neoplastic gastric mucosa (non-NGM) of patients with early GC. The methylation status of the SOCS3 gene promoter was analyzed using methylation-specific PCR in the non-NGM of patients with or without early GC. Expression levels of p-STAT3 and Ki67 were investigated immunohistochemically in non-NGM with early GC before and after H. pylori eradication. In non-NGM, SOCS3 promoter methylation was detected in 17/51 patients (33.3%) with early GC. In those patients, the non-NGM labeling indices of both Ki67 and p-STAT3 were significantly higher compared with that in patients with early GC without SOCS3 methylation. A significant correlation between Ki67 and p-STAT3 expression levels was demonstrated in the non-NGM of patients with early GC. In patients with early GC without SOCS3 methylation, the labeling indices of both Ki67 and p-STAT3 in non-NGM were significantly reduced after H. pylori eradication, whereas no such change was observed in patients with early GC with SOCS3 methylation. SOCS3 methylation is associated with continuous p-STAT3 overexpression and enhanced epithelial cell proliferation in non-NGM of patients with early GC.

Incidence and treatment of metachronous gastric cancer after proximal gastrectomy

BACKGROUND AND PURPOSE

Proximal gastrectomy (PG) is a widely accepted function-preserving surgical procedure; however, the incidence and treatment of metachronous gastric cancer (MGC) after PG have been the subject of a number of reports.

METHODS

We collected data from 1576 consecutive patients who underwent gastrectomy for gastric cancer between January, 2003 and December, 2010, and analyzed the outcomes of 671 patients treated with PG or distal gastrectomy (DG) for cT1N0 disease. We also discuss the treatments for MGC.

RESULTS

MGC was diagnosed within a median follow-up of 52.8 months after PG and DG in six (6.6%) and nine (1.8%) patients, respectively. The cumulative prevalence of MGC after PG was significantly higher than that after DG; P = 0.005. Univariate and multivariate analysis revealed male sex and PG as significant risk factors for MGC (P = 0.014 and P = 0.026, respectively). Five of the six patients who underwent PG were treated by endoscopic submucosal dissection.

CONCLUSIONS

The incidence of MGC after PG was significantly higher than that after DG. However, most of the MGCs that developed after PG could be treated by endoscopic submucosal dissection.

Common Variable Immunodeficiency and Gastric Malignancies

Common variable immunodeficiency (CVID) is an immunodeficiency disorder with a high incidence of gastrointestinal manifestations and an increased risk of gastric carcinoma and lymphoma. This review discusses the latest advancements into the immunological, clinical and diagnostic aspects of gastric malignancies in patients with CVID. The exact molecular pathways underlying the relationships between CVID and gastric malignancies remain poorly understood. These include genetics, immune dysregulation and chronic infections by Helicobacter pylori. Further studies are needed to better stratify the risk for cancer in these patients, to elaborate surveillance programs aimed at preventing these complications, and to develop new and more effective therapeutic approaches.

Serum pepsinogen 1 and anti-Helicobacter pylori IgG antibodies as predictors of gastric cancer risk in Finnish males

BACKGROUND

Serum pepsinogen 1 (SPG1) and anti-Helicobacter pylori serology have been used for gastric risk stratification in Asia.

AIM

To assess utility of these markers in a Western population.

METHODS

SPG1 measurements were available for 21 895 Finnish male smokers in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. We used Cox proportional hazards models adjusted for potential confounders to estimate gastric cancer hazard ratios (HR) and 95% confidence intervals (95% CI) for low SPG1 (<25 μg/L). In a subset (n = 3555) with anti-H. pylori serology, these markers jointly defined the following: Group A (H. pylori[-], SPG1[normal]; reference group), Group B (H. pylori[+], SPG1[normal]), Group C (H. pylori[+], SPG1[low]) and Group D (H. pylori[-], SPG1[low]). Odds ratios (ORs) and 95% CI were calculated using multivariate logistic regression.

RESULTS

There were 329 gastric cancers diagnosed an average of 13.9 years after baseline. Pre-diagnostic low SPG1 was significantly associated with increased gastric cancer risk (HR 2.68, 95% CI 1.99-3.61). Among subjects with both SPG1 and H. pylori serology, groups B, C and D had increased gastric cancer ORs (95% CI) of 1.79 (1.21-2.64), 3.85 (2.36-6.28) and 6.35 (2.20-18.34), respectively. CagA seropositives had significantly higher ORs than CagA seronegatives within group B (P_{heterogeneity}  = 0.01). For groups B and C, repeat SPG1 level at 3 years did not further stratify gastric cancer risk.

CONCLUSIONS

Low SPG1 was associated with increased gastric cancer risk in our large Finnish cohort. A single measurement of SPG1 along with H. pylori whole cell and CagA serology provides potentially useful prediction of gastric cancer risk.

Helicobacter pylori-induced gastric pathology: insights from in vivo and ex vivo models

Gastric colonization with Helicobacter pylori induces diverse human pathological conditions, including superficial gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric adenocarcinoma and its precursors. The treatment of these conditions often relies on the eradication of H. pylori, an intervention that is increasingly difficult to achieve and that does not prevent disease progression in some contexts. There is, therefore, a pressing need to develop new experimental models of H. pylori-associated gastric pathology to support novel drug development in this field. Here, we review the current status of in vivo and ex vivo models of gastric H. pylori colonization, and of Helicobacter-induced gastric pathology, focusing on models of gastric pathology induced by H. pylori, Helicobacter felis and Helicobacter suis in rodents and large animals. We also discuss the more recent development of gastric organoid cultures from murine and human gastric tissue, as well as from human pluripotent stem cells, and the outcomes of H. pylori infection in these systems.

Epidemiology and pathophysiology of malignancy in common variable immunodeficiency?

Common variable immunodeficiency (CVID) is a diagnostic category of primary immunodeficiency (PID) which may present with heterogeneous disorders including recurrent infections, autoimmunity, granulomatous diseases, lymphoid and other types of malignancies. Generally, the incidence of malignancy in CVID patients is around 1.5-20.7% and usually occurs during the 4th-6th decade of life. Non-Hodgkin lymphoma is the most frequent malignancy, followed by epithelial tumours of stomach, breast, bladder and cervix. The exact pathological mechanisms for cancer development in CVID are not fully determined; however, several mechanisms including impaired genetic stability, genetic predisposition, immune dysregulation, impaired clearance of oncogenic viruses and bacterial infections, and iatrogenic causes have been proposed to contribute to the high susceptibility of these patients to malignancies.

Risk of gastric cancer in Helicobacter pylori infection in a 15-year follow-up

OBJECTIVE

We investigated the risk of gastric cancer among men with Helicobacter pylori (H. pylori) infection or atrophic gastritis (AG) in a 15-year follow-up.

MATERIALS AND METHODS

Study population consists of 12,016 men aged 50-65 years at the beginning of the follow-up in 1994-1996. Serum levels of pepsinogen I (SPGI) and antibodies (IgG) to H. pylori (HpAb) were assayed from serums collected in 1994-1996. Incidence of gastric cancer in the study population was assessed in follow-up from 1994 to 2011 by data from the nationwide cancer registry. Based on SPGI and HpAb values, standardized incidence ratios (SIRs) of gastric cancer were calculated in three subgroups, that is, in those with a healthy stomach, those with H. pylori infection but without AG and those with AG. Risk ratios (RR) of gastric cancer were calculated using SIR of subgroups.

RESULTS

During 15 years, seven gastric cancers appeared per 79,928 person years among men with healthy stomachs, 50 cancers per 92,533 person years in men with H. pylori infection but without AG, and 8 per 8658 person years in men with AG. Risk ratio (RR) of stomach cancer in men with H. pylori infection was 5.8 (95%CI: 2.7-15.3) compared to men with healthy stomachs, and 9.1 (95%CI: 2.9-30.0) in men with AG. There were no differences in cancer risk between cardia and distal stomach.

CONCLUSIONS

Risk of gastric cancer is low in men with healthy stomachs. It is significantly increased in those with H. pylori infection and more in those with AG.

Systems-wide analyses of mucosal immune responses to Helicobacter pylori at the interface between pathogenicity and symbiosis

Helicobacter pylori is the dominant member of the gastric microbiota in over half of the human population of which 5-15% develop gastritis or gastric malignancies. Immune responses to H. pylori are characterized by mixed T helper cell, cytotoxic T cell and NK cell responses. The presence of Tregs is essential for the control of gastritis and together with regulatory CX3CR1+ mononuclear phagocytes and immune-evasion strategies they enable life-long persistence of H. pylori. This H. pylori-induced regulatory environment might contribute to its cross-protective effect in inflammatory bowel disease and obesity. Here we review host-microbe interactions, the development of pro- and anti-inflammatory immune responses and how the latter contribute to H. pylori's role as beneficial member of the gut microbiota. Furthermore, we present the integration of existing and new data into a computational/mathematical model and its use for the investigation of immunological mechanisms underlying initiation, progression and outcomes of H. pylori infection.

Training in early gastric cancer diagnosis improves the detection rate of early gastric cancer: an observational study in China

Few studies have analyzed the training of endoscopists in the diagnosis of early gastric cancer (EGC). This study assessed whether specific training of endoscopists improves the detection rate of EGC. The rates of detection of EGC by endoscopists at the Digestive Endoscopy Center of the Affiliated Nanfang Hospital of China Southern Medical University between January 2013 and May 2014 were retrospectively analyzed. Because some endoscopists received training in the diagnosis of EGC, beginning in September 2013, the study was divided into 3 time periods: January to September 2013 (period 1), September 2013 to January 2014 (period 2), and January to May 2014 (period 3). The rates of EGC detection during these 3 periods were analyzed. From January 2013 to May 2014, a total of 25,314 gastroscopy examinations were performed at our center, with 48 of these examinations (0.2%) detecting EGCs, accounting for 12.1% (48/396) of the total number of gastric cancers detected. The EGC detection rates by trained endoscopists during periods 1, 2, and 3 were 0.3%, 0.6%, and 1.5%, respectively, accounting for 22.0%, 39.0%, and 60.0%, respectively, of the gastric cancers detected during these time periods. In comparison, the EGC detection rates by untrained endoscopists during periods 1, 2, and 3 were 0.05%, 0.08%, and 0.10%, respectively, accounting for 3.1%, 6.0%, and 5.7%, respectively, of the gastric cancers detected during these times. After training, the detection rate by some trained endoscopists markedly increased from 0.2% during period 1 to 2.3% during period 3. Further, the use of magnifying endoscopy with narrow-band imaging (M-NBI) (odds ratio = 3.1, 95% confidence interval 2.4-4.1, P < 0.001) contributed to the diagnosis of EGC. In conclusion, specific training could improve the endoscopic detection rate of EGC. M-NBI contributed to the diagnosis of EGC.

Helicobacter pylori infection, gastrin and cyclooxygenase-2 in gastric carcinogenesis

Gastric cancer is one of the most frequent neoplasms and a main cause of death worldwide, especially in China and Japan. Numerous epidemiological, animal and experimental studies support a positive association between chronic Helicobacter pylori (H. pylori) infection and the development of gastric cancer. However, the exact mechanism whereby H. pylori causes gastric carcinogenesis remains unclear. It has been demonstrated that expression of cyclooxygenase-2 (COX-2) is elevated in gastric carcinomas and in their precursor lesions. In this review, we present the latest clinical and experimental evidence showing the role of gastrin and COX-2 in H. pylori-infected patients and their possible association with gastric cancer risk.

Tumor-based case-control studies of infection and cancer: muddling the when and where of molecular epidemiology

We describe the "tumor-based case-control" study as a type of epidemiologic study used to evaluate associations between infectious agents and cancer. These studies assess exposure using diseased tissues from affected individuals (i.e., evaluating tumor tissue for cancer cases), but they must utilize nondiseased tissues to assess control subjects, who do not have the disease of interest. This approach can lead to exposure misclassification in two ways. First, concerning the "when" of exposure assessment, retrospective assessment of tissues may not accurately measure exposure at the key earlier time point (i.e., during the etiologic window). Second, concerning the "where" of exposure assessment, use of different tissues in cases and controls can have different accuracy for detecting the exposure (i.e., differential exposure misclassification). We present an example concerning the association of human papillomavirus with various cancers, where tumor-based case-control studies likely overestimate risk associated with infection. In another example, we illustrate how tumor-based case-control studies of Helicobacter pylori and gastric cancer underestimate risk. Tumor-based case-control studies can demonstrate infection within tumor cells, providing qualitative information about disease etiology. However, measures of association calculated in tumor-based case-control studies are prone to over- or underestimating the relationship between infections and subsequent cancer risk.

Novel insights on the role of CD8+ T cells and cytotoxic responses during Helicobacter pylori infection

Helicobacter pylori chronically persists in 50% of the human population and causes serious gastric and duodenal pathologies in 15% of infected people. Research on the immune response to the infection has mainly focused on the induction of CD4+ T cell responses. Human studies emphasize the potential clinical relevance of CD8+ cytotoxic T lymphocytes, however this cell type has barely been reported in studies employing mouse or gerbil models. Traditionally characterized as an extracellular bacterium, H. pylori has been identified inside epithelial and immune cells. Similarly to other intracellular bacteria, H. pylori infection of macrophages can alter autophagy and phagosome processing. A novel animal model of H. pylori infection demonstrates for the first time the induction of cytotoxic CD8+ T cell responses in pigs and localization of intracellular H. pylori within lymphoid aggregates. Here, we discuss novel mechanisms of host-H. pylori interactions that could lead to the induction of cytotoxic responses.

Helicobacter pylori CagA and VacA genotypes and gastric phenotype: a meta-analysis

BACKGROUND

CagA+ and vacuolizing cytotoxin (VacA)-specific strains of Helicobacter pylori have been associated with different risks for developing gastric lesions. We aim to summarize a possible association between these genotypes and the risk for developing different gastric phenotypes.

MATERIALS AND METHODS

A MEDLINE database (PubMed) search was performed and a meta-analysis conducted.

RESULTS

Forty-four studies were retrieved, all with either a case-control (n=13) or cross-sectional (n=31) design, including 17 374 patients. CagA positivity was associated with an increased risk for gastric cancer [odds ratio (OR) 2.09 (95% confidence interval (CI), 1.48-2.94)] compared with that in individuals without gastric lesions [OR 2.44 (95% CI 1.27-4.70)] and in those with previously identified gastritis. In addition, there was an increased risk for peptic ulcer disease [OR 1.69 (95% CI 1.12-2.55)]. Individuals harboring the H. pylori strains VacA s1 (vs. s2), m1 (vs. m2), s1m1 (vs. s1m2), and s1m1 (vs. s2m2) had an increased risk for development of cancer [OR of 5.32 (95% CI 2.76-10.26), 2.50 (95% CI 1.67-3.750), 2.58 (95% CI 1.24-5.38), and 4.36 (95% CI 2.08-9.10), respectively]. s1m1 strains (vs. s2m2) were also associated with peptic ulcer disease [OR 2.04 (1.01-4.13)].

CONCLUSION

Our results indicate that individuals infected with CagA+ H. pylori strains and those infected with VacA s1 and m1 strains have an increased risk for gastric cancer. Cohort studies are welcome to integrate this information in the management of at-risk individuals such as those with precancerous cancer conditions and/or a family history of gastric cancer.

Gastric cancer chemoprevention: the current evidence

Chemoprevention may form the cornerstone in the management of gastric adenocarcinoma of the future. Helicobacter pylori eradication and aspirin and/or nonsteroidal anti-inflammatory drug therapy have emerged as front-runner chemotherapeutic agents due to the putative pathogenic mechanisms that they address. Before a population-based chemopreventive strategy can be recommended on a large scale, randomized controlled trials with follow-up of more than 10 years of these 2 agents in populations at high gastric adenocarcinoma risk is urgently awaited.

Overview of methodological quality of systematic reviews about gastric cancer risk and protective factors

BACKGROUND AND OBJECTIVE

A comprehensive overall review of gastric cancer (GC) risk and protective factors is a high priority, so we conducted the present study.

METHODS

Systematic searches in common medical electronic databases along with reference tracking were conducted to include all kinds of systematic reviews (SRs) about GC risk and protective factors. Two authors independently selected studies, extracted data, and evaluated the methodological qualities and the quality of evidence using R-AMSTAR and GRADE approaches.

RESULTS

Beta- carotene below 20 mg/day, fruit, vegetables, non-fermented soy-foods, whole-grain, and dairy product were GC protective factors, while beta-carotene 20 mg/day or above, pickled vegetables, fermented soy-foods, processed meat 30 g/d or above, or salty foods, exposure to alcohol or smoking, occupational exposure to Pb, overweight and obesity, helicobacter pylori infection were GC risk factors. So we suggested screening and treating H. pylori infection, limiting the amount of food containing risk factors (processed meat consumption, beta-carotene, pickled vegetables, fermented soy-foods, salty foods, alcohol), stopping smoking, avoiding excessive weight gain, avoidance of Pb, and increasing the quantity of food containing protective components (fresh fruit and vegetables, non-fermented soy-foods, whole-grain, dairy products).

CONCLUSIONS

The conclusions and recommendations of our study were limited by including SRs with poor methodological bases and low quality of evidence, so that more research applying checklists about assessing the methodological qualities and reporting are needed for the future.

Endoscopy in screening for digestive cancer

The aim of this study is to describe the role of endoscopy in detection and treatment of neoplastic lesions of the digestive mucosa in asymptomatic persons. Esophageal squamous cell cancer occurs in relation to nutritional deficiency and alcohol or tobacco consumption. Esophageal adenocarcinoma develops in Barrett's esophagus, and stomach cancer in chronic gastric atrophy with Helicobacter pylori infection. Colorectal cancer is favoured by a high intake in calories, excess weight, low physical activity. In opportunistic or individual screening endoscopy is the primary detection procedure offered to an asymptomatic individual. In organized or mass screening proposed by National Health Authorities to a population, endoscopy is performed only in persons found positive to a filter selection test. The indications of primary upper gastrointestinal endoscopy and colonoscopy in opportunistic screening are increasingly developing over the world. Organized screening trials are proposed in some regions of China at high risk for esophageal cancer; the selection test is cytology of a balloon or sponge scrapping; they are proposed in Japan for stomach cancer with photofluorography as a selection test; and in Europe, America and Japan; for colorectal cancer with the fecal occult blood test as a selection test. Organized screening trials in a country require an evaluation: the benefit of the intervention assessed by its impact on incidence and on the 5 year survival for the concerned tumor site; in addition a number of bias interfering with the evaluation have to be controlled. Drawbacks of screening are in the morbidity of the diagnostic and treatment procedures and in overdetection of none clinically relevant lesions. The strategy of endoscopic screening applies to early cancer and to benign adenomatous precursors of adenocarcinoma. Diagnostic endoscopy is conducted in 2 steps: at first detection of an abnormal area through changes in relief, in color or in the course of superficial capillaries; then characterization of the morphology of the lesion according to the Paris classification and prediction of the risk of malignancy and depth of invasion, with the help of chromoscopy, magnification and image processing with neutrophil bactericidal index or FICE. Then treatment decision offers 3 options according to histologic prediction: abstention, endoscopic resection, surgery. The rigorous quality control of endoscopy will reduce the miss rate of lesions and the occurrence of interval cancer.

Helicobacter pylori colonization ameliorates glucose homeostasis in mice through a PPAR γ-dependent mechanism

Background

There is an inverse secular trend between the incidence of obesity and gastric colonization with Helicobacter pylori, a bacterium that can affect the secretion of gastric hormones that relate to energy homeostasis. H. pylori strains that carry the cag pathogenicity island (PAI) interact more intimately with gastric epithelial cells and trigger more extensive host responses than cag⁻ strains. We hypothesized that gastric colonization with H. pylori strains differing in cag PAI status exert distinct effects on metabolic and inflammatory phenotypes.

Methodology/Principal Findings

To test this hypothesis, we examined metabolic and inflammatory markers in db/db mice and mice with diet-induced obesity experimentally infected with isogenic forms of H. pylori strain 26695: the cag PAI wild-type and its cag PAI mutant strain 99–305. H. pylori colonization decreased fasting blood glucose levels, increased levels of leptin, improved glucose tolerance, and suppressed weight gain. A response found in both wild-type and mutant H. pylori strain-infected mice included decreased white adipose tissue macrophages (ATM) and increased adipose tissue regulatory T cells (Treg) cells. Gene expression analyses demonstrated upregulation of gastric PPAR γ-responsive genes (i.e., CD36 and FABP4) in H. pylori-infected mice. The loss of PPAR γ in immune and epithelial cells in mice impaired the ability of H. pylori to favorably modulate glucose homeostasis and ATM infiltration during high fat feeding.

Conclusions/Significance

Gastric infection with some commensal strains of H. pylori ameliorates glucose homeostasis in mice through a PPAR γ-dependent mechanism and modulates macrophage and Treg cell infiltration into the abdominal white adipose tissue.

Chemoprevention for gastric cancer

Gastric cancer remains the fourth commonest cancer, and the second commonest cause of cancer death, globally. Chemopreventive strategies to reduce the incidence of gastric cancer are required, particularly as the number of deaths per year is likely to rise for the foreseeable future. There is some evidence that population screening and treatment for Helicobacter pylori in high-risk populations may reduce incidence of gastric cancer. Trials studying the effect of anti-oxidants and selenium are conflicting. A recent meta-analysis demonstrated that aspirin use led to a reduced risk of gastric cancer after 10-20 years of follow-up. There is little convincing evidence that statins have any effect on risk of gastric cancer. More trials on chemoprevention for gastric cancer are therefore urgently required.

Review of gastric cancer risk factors in patients with common variable immunodeficiency disorders, resulting in a proposal for a surveillance programme

Common variable immunodeficiency disorders (CVIDs) are the most frequent symptomatic primary immunodeficiencies in adults. They comprise a heterogeneous group of pathologies, with frequent non-infectious complications in addition to the bacterial infections that usually characterize their presentation. Complications include a high risk of malignancy, especially lymphoma and gastric cancer. Helicobacter pylori infection and pernicious anaemia are risk predictors for gastric cancer in the general population and probably in patients with CVIDs. Screening for gastric cancer in a high-risk population appears to improve survival. Given the increased risk of gastric cancer in patients with CVIDs and prompted by a case of advanced gastric malignancy in a patient with a CVID and concomitant pernicious anaemia, we performed a review of the literature for gastric cancer and conducted a cohort study of gastric pathology in 116 patients with CVIDs under long-term follow-up in Oxford. Regardless of the presence of pernicious anaemia or H. pylori infection, patients with CVIDs have a 10-fold increased risk of gastric cancer and are therefore a high-risk population. Although endoscopic screening of all patients with CVIDs could be considered, a more selective approach is appropriate and we propose a surveillance protocol that should reduce modifiable risk factors such as H. pylori, in order to improve the management of patients with CVIDs at risk of gastric malignancy.

Combined effect of miR-146a rs2910164 G/C polymorphism and Toll-like receptor 4 +3725 G/C polymorphism on the risk of severe gastric atrophy in Japanese

BACKGROUND

A G/C polymorphism in miRNA-146a (rs2910164) was shown to be associated with the risk of hepatocellular carcinoma.

OBJECTIVE

This study aimed to examine the associations of the miR-146a G/C (rs2910164) and TLR4 +3725 G/C (rs11536889) polymorphisms with the risk of Helicobacter pylori (H. pylori) infection, gastric atrophy, and gastric cancer in a Japanese population.

METHODS

Subjects for this study were 583 histologically diagnosed gastric cancer patients and age- and sex-frequency-matched 1,742 control outpatients (1,637 subjects were eligible for the analyses), who visited Aichi Cancer Center Hospital from the year 2001 to 2005. Serum pepsinogens were measured to evaluate gastric atrophy.

RESULTS

When H. pylori-seropositive subjects or subjects with gastric atrophy were defined as H. pylori-infected subjects, the age- and sex-adjusted odds ratio (aOR) of severe gastric atrophy among the H. pylori infected was 1.44 (95% confidence interval [95% CI]=0.89-2.34, p=0.133) in G/G genotype of miR-146a polymorphism. When combined with TLR4 G/C polymorphism, the OR in those with miR-146a G/G and TLR4 G/C+C/C genotypes was significantly increased relative to those with miR-146a C/C+G/C and TLR4 G/G among the H. pylori-infected subjects: aOR=2.04 (95% CI=1.10-3.82, p=0.025).

CONCLUSIONS

This study revealed the combined effect of miR-146a rs2910164 G/G and TLR4 +3725 C allele on the increased risk of severe gastric atrophy among the H. pylori-infected Japanese subjects.

Gastric juice prostaglandins and peptide growth factors as potential markers of chronic atrophic gastritis, intestinal metaplasia and gastric cancer: their potential clinical implications based on this pilot study

BACKGROUND

Gastric secretion can provide valuable information especially when Helicobacter pylori (Hp) infection results in chronic atrophic gastritis (CAG) and intestinal metaplasia (IM) preceding adenocarcinoma (AdCa).

AIMS

Looking for a potential biomarker of malignant transformation in the setting of chronic inflammation we studied the levels of prostaglandin E2 (PGE(2)), as well as peptide growth factors [epidermal growth factor (EGF) and transforming growth factor α (TGFα)], harbingers of injury and repair, in gastric juice aspirated at endoscopy from patients with CAG, CAG/IM, AdCa, and controls.

METHODS

The PGE(2), EGF and TGFα concentrations in the gastric juice were measured using radioimmunoassays (RIAs).

RESULTS

In patients with AdCa gastric juice PGE(2) increased fivefold versus controls (P < 0.01) and almost threefold versus patients with CAG (P < 0.05). The EGF levels in patients with AdCa were fourfold higher versus controls (P < 0.001) and almost threefold higher versus CAG (P < 0.05). In patients with CAG/IM the EGF levels were also almost 3 times higher versus controls. The TGFα levels in patients with AdCa were half the value of controls and CAG (P < 0.05). In patients with CAG/IM the levels were as low as 1/5 of controls or CAG (P < 0.05).

CONCLUSIONS

Testing the gastric juice for PGE(2), EGF, and TGFα in patients with endoscopy and biopsy proven CAG, may be helpful in follow up of patients who may potentially progress to IM and ultimately AdCa. This could be considered as an adjunct to histologic assessment especially that even the best surveillance biopsy specimen regimens are inherited with sampling errors.

Epidemiological review of gastric cancer in India

Stomach cancer is the one of the leading cause of cancer in southern region of India. Its incidence is decreasing worldwide yet on global scale stomach cancer remains one of the most common causes of cancer death. Etiology of gastric cancer includes Helicobacter pylori infection, diet and lifestyle, tobacco, alcohol and genetic susceptibility. In this review, we tried to find the contribution of Indian scientist in understanding the descriptive and observational epidemiology of stomach cancer. PubMed was used as a search platform using key words such as "stomach cancer, treatment, clinical characteristics, stomach cancer outcome, epidemiology, etiological factor and their corresponding Mesh terms were used in combination with Boolean operators OR, AND". Most of the reported studies on gastric cancer from India are case report or case series and few are case-control studies. Indian studies on this topic are limited and have observed H. pylori infection, salted tea, pickled food, rice intake, spicy food, soda (additive of food), tobacco and alcohol as risk factors for gastric cancer. More research is required to understand the etiology, develop suitable screening test, to demarcate high-risk population and to develop and evaluate the effect of primary prevention programs.

TLR-2-activated B cells suppress Helicobacter-induced preneoplastic gastric immunopathology by inducing T regulatory-1 cells

B cells regulate autoimmune pathologies and chronic inflammatory conditions such as autoimmune encephalomyelitis and inflammatory bowel disease. The potential counterregulatory role of B cells in balancing pathogen-specific immune responses and the associated immunopathology is less well understood owing to the lack of appropriate persistent infection models. In this paper, we show that B cells have the ability to negatively regulate adaptive immune responses to bacterial pathogens. Using mouse models of infection with Helicobacter felis, a close relative of the human gastrointestinal pathogen H. pylori, we found that B cells activated by Helicobacter TLR-2 ligands induce IL-10-producing CD4(+)CD25(+) T regulatory-1 (Tr-1)-like cells in vitro and in vivo. Tr-1 conversion depends on TCR signaling and a direct T-/B-interaction through CD40/CD40L and CD80/CD28. B cell-induced Tr-1 cells acquire suppressive activity in vitro and suppress excessive gastric Helicobacter-associated immunopathology in vivo. Adoptive cotransfer of MyD88-proficient B cells and Tr-1 cells restores a normal gastric mucosal architecture in MyD88(-/-) and IL-10(-/-) mice in a manner that depends on T cellular, but not B cellular, IL-10 production. Our findings describe a novel mechanism of B cell-dependent Tr-1 cell generation and function in a clinically relevant disease model. In conclusion, we demonstrate that the B cell/Tr-1 cell axis is essential for balancing the control of Helicobacter infection with the prevention of excessive Th1-driven gastric immunopathology, promoting gastric mucosal homeostasis on the one hand and facilitating Helicobacter persistence on the other.

Genetic predisposition to Helicobacter pylori-induced gastric precancerous conditions

Gastric cancer is the most common malignancy of the gastrointestinal tract in East Asian populations and the second most frequent cause of cancer-related mortality in the world. While previous studies have investigated the genetic factors involved in gastric carcinogenesis, there still exist relatively few studies that have investigated the genetic traits associated with the risk of gastric precancerous conditions. In this paper we will review the biology and genetic polymorphisms involved in the genesis of gastric precancerous conditions reported to date and discuss the future prospects of this field of study. The associations of gastric precancerous conditions with polymorphisms in the cytotoxin-associated gene A-related genes (e.g. PTPN11 G/A at intron 3, rs2301756), those in the genes involved in host immunity against Helicobacter pylori (H. pylori) infection (e.g. TLR4 +3725G/C, rs11536889) or polymorphisms of the genes essential for the development/ differentiation of the gastric epithelial cells (e.g. RUNX3 T/A polymorphism at intron 3, rs760805) have been reported to date. Genetic epidemiological studies of the associations between H. pylori-induced gastric precancerous conditions and other gene polymorphisms in these pathways as well as polymorphisms of the genes involved in other pathways like oxidative DNA damage repair pathways would provide useful evidence for the individualized prevention of these H. pylori-induced gastric precancerous conditions.

Recent knowledge of the relationship between Helicobacter pylori and gastric cancer and recent progress of gastroendoscopic diagnosis and treatment for gastric cancer

Gastric cancer is a multi-step process and multi-factorial disease. However, Helicobacter pylori plays the most important role in gastric carcinogenesis because most gastric cancers including both intestinal type and diffuse type arise from mucosa infected by H. pylori. The relationship between H. pylori infection and gastric cancer has been proved in epidemiological studies, animal experiments with Mongolian gerbils, and clinical prospective studies. Significant preventive effect of H. pylori eradication was reported in Japanese randomized study for secondary gastric cancer after endoscopic resection of primary gastric cancer and meta-analysis of randomized studies. The Japanese Society for Helicobacter Research has published a guideline recommending that H. pylori infection should be treated by eradication therapy to suppress the incidence of gastric cancer. The development of endoscopic technology has advanced the diagnosis and treatment of gastric cancer. In the diagnosis of gastric cancer, image enhancement endoscopy including magnifying observation with narrow-band imaging system and microscopic magnifying observation opens the possibility of optical biopsy. Endoscopic resection for early stage of gastric cancer has been established as proper treatment of early gastric cancer. Recently endoscopic submucosal dissection had made en bloc resection possible for mucosal cancers >2 cm in diameter. Because of endoscopic submucosal dissection, endoscopic resection is indicated in a greater number of cases. Although the use of endoscopic treatment for gastric cancer has been increasing steadily, long-term outcome data is necessary.

Epidemiological aspects of gastric adenocarcinoma: are predictive diagnostics and targeted preventive measures possible?

The incidence of gastric cancer has witnessed major changes over the past decades. Until recently, gastric cancer was a common malignancy in most countries. A striking decline in incidence in most Western populations has occurred since the 1970s, and elucidating the detailed causes for this trend can potentially be of great value for targeted preventive measures. Furthermore, it can add to the understanding of malignant disease and prevention in general. Moreover, the absolute number of cases worldwide is predicted to increase during many years to come. Gastric cancer is typically diagnosed at an advanced stage in symptomatic patients, and there are often no effective curative or palliative or therapeutic options. This fact highlights the need for research aiming to increase our understanding of the etiology of this cancer, facilitating the design of successful targeted preventive strategies for different populations. The future outlook in terms of decreasing gastric cancer deaths would be to identify such intelligent diagnostic tools. In this article, we present a summary of the epidemiology of gastric cancer, with special focus on its etiology.

Prostaglandin E2 prevents Helicobacter-induced gastric preneoplasia and facilitates persistent infection in a mouse model

BACKGROUND & AIMS

Persistent infection with the human pathogen Helicobacter pylori increases the risk of gastric cancer. In this study, we investigated the role of cyclooxygenase-2 (COX-2) and its main product, prostaglandin E(2) (PGE(2)), in the development of Helicobacter-induced gastritis and gastric cancer precursor lesions.

METHODS

We utilized mouse models of Helicobacter-induced gastric preneoplasia and vaccine-induced protection to study the effects of COX-2 inhibition and PGE(2) treatment on the induction of Helicobacter-specific immune responses and gastric premalignant immunopathology.

RESULTS

COX-2 and PGE(2) are up-regulated upon Helicobacter infection in cultured epithelial cells and in the gastric mucosa of infected mice. Inhibition of COX-2 activity with celecoxib significantly accelerated early preneoplasia; conversely, systemic administration of synthetic PGE(2) prevented development of premalignant pathology and completely reversed preexisting lesions by suppressing interferon-gamma production in the infected stomachs. The protective effect of PGE(2) was accompanied by increased Helicobacter colonization in all models. All in vivo effects were attributed to immunosuppressive effects of PGE(2) on CD4(+) T-helper 1 cells, which fail to migrate, proliferate, and secrete cytokines when exposed to PGE(2) in vitro and in vivo. T-cell inhibition was found to be due to silencing of interleukin-2 gene transcription, and could be overcome by supplementation with recombinant interleukin-2 in vitro and in vivo.

CONCLUSIONS

COX-2-dependent production of PGE(2) has an important immunomodulatory role during Helicobacter infection, preventing excessive local immune responses and the associated immunopathology by inhibiting the effector functions of pathogenic T-helper 1 cells.

Significant association of RUNX3 T/A polymorphism at intron 3 (rs760805) with the risk of gastric atrophy in Helicobacter pylori seropositive Japanese

BACKGROUND

This study aimed to examine the associations of a RUNX3 T/A polymorphism at exon 1 (Asn18Ile) (rs6672420) and another RUNX3 intronic T/A polymorphism (rs760805) with the risk of gastric cancer together with the risk of H. pylori seropositivity and gastric atrophy in Japanese people.

METHODS

Study subjects were 583 histologically diagnosed gastric cancer patients and age- and sex-frequency-matched 1,742 control outpatients (among whom 1,637 subjects were eligible for the analyses), who visited Aichi Cancer Center Hospital from 2001 to 2005. Serum pepsinogens were measured to evaluate gastric atrophy.

RESULTS

There was no significant association between the RUNX3 polymorphisms and the seropositivity. Among H. pylori seropositive subjects, we found a significant association between RUNX3 rs760805 polymorphism and the risk of gastric atrophy with the age- and sex-adjusted OR of 1.51 (95% CI 1.11-2.05, P = 0.008) in T/A, 1.59 (95% CI 1.08-2.33, P = 0.019) in A/A, and 1.53 (95% CI 1.14-2.05, P = 0.004) in T/A + A/A, compared with T/T genotype. We found no statistically significant associations between RUNX3 rs6672420 polymorphism and risk of gastric atrophy, nor between these two RUNX3 polymorphisms and the risk of gastric cancer relative to the subjects with gastric atrophy.

CONCLUSIONS

Our study results revealed that the RUNX3 intronic T/A polymorphism (rs760805) might modulate the risk of gastric atrophy among H. pylori seropositive subjects, and the RUNX3 T/A polymorphism at exon 1 (rs6672420) had little influence on the risks of H. pylori infection, gastric atrophy or gastric cancer in Japanese people. Further investigation is required to verify our findings.

Differential oncogenic potential of geographically distinct Helicobacter pylori CagA isoforms in mice

Infection with cagA-positive Helicobacter pylori is associated with gastric carcinoma. The cagA-encoded CagA protein is delivered into gastric epithelial cells and, upon tyrosine phosphorylation at the C-terminal EPIYA segments, binds and deregulates SHP-2 oncoprotein. On the basis of the differential alignment of the EPIYA segments, CagA can be subdivided into Western CagA, which is produced by H. pylori isolated in Western countries, and East Asian CagA, which is produced by H. pylori circulating in East Asian countries. Western CagA contains EPIYA-A, EPIYA-B and variable numbers of EPIYA-C segments, whereas East Asian CagA contains EPIYA-A, EPIYA-B and variable numbers of EPIYA-D segments. Upon tyrosine phosphorylation, EPIYA-C and EPIYA-D, respectively, serve as low-affinity and high-affinity SHP-2-binding sites. We previously reported that systemic expression of East Asian CagA (CagA-ABDD) induces gastrointestinal and hematopoietic malignancies in mice. In this study, we generated transgenic mice that systemically express Western CagA (CagA-ABCCC), the levels of which are comparable to those in mice expressing East Asian CagA. The mice developed gastric epithelial hypertrophy and gastrointestinal tumors and also showed lymphoid abnormality but not myeloid abnormalities such as granulocytosis and myeloid leukemia found in mice carrying East Asian CagA. The incidence of tumors in mice expressing Western CagA was significantly lower than that in mice expressing East Asian CagA. Our results indicate that Western CagA is qualitatively less oncogenic than East Asian CagA. Differential oncogenic potential of geographically distinct CagA isoforms may contribute to the differential prevalence of gastric carcinoma between East Asian countries and Western countries.