Relevance of Helicobacter pylori vacA 3'-end Region Polymorphism to Gastric Cancer

Helicobacter pylori cagA, vacA, iceA and babA Genotypes from Peruvian Patients with Gastric Intestinal Metaplasia

We explored the clinical-stage association of gastric intestinal metaplasia (IM) compared to cases of chronic non-atrophic gastritis (CNAG) and its relationship with virulence genotypes of Helicobacter pylori (H. pylori) clinical isolates from patients with dyspepsia in Peru. This study was cross-sectional and included 158 H. pylori clinical isolates; each isolate corresponded to a different Peruvian patient, genotyped by polymerase chain reaction to detect cagA gene and EPIYA motifs, the vacA gene (alleles s1, s2, i1, i2, d1, d2, m1, m2 and subtypes s1a, s1b and s1c), the iceA gene (alleles 1 and 2), and the babA gene (allele 2). We observed that 38.6% presented with IM and that all clinical isolates were CagA positive. The EPIYA-ABC motif was predominant (68.4%), and we observed a high frequency for the vacA gene alleles s1 (94.9%), m1 (81.7%), i1 (63.9%), and d1 (70.9%). Strains with both iceA alleles were also detected (69.6%) and 52.2% were babA2 positive. In addition, it was observed that the cagA+/vacAs1m1 (PR: 2.42, 1.14 to 5.13, p < 0.05) and cagA+/vacAs1am1 (PR: 1.67, 1.13 to 2.45, p < 0.01) genotypes were associated with IM. Our findings revealed the cagA and vacA risk genotypes predominance, and we provided clinically relevant associations between Peruvian patients with H. pylori infection and IM clinical stage.

Exploring virulence factors of Helicobacter pylori isolated from gastric biopsy

BACKGROUND

Helicobacter pylori (H. pylori) colonizes human gastric mucosa and is classified as class one carcinogenic bacteria. In this regard, this study aimed to detect major virulence factors in H. pylori strains recovered from gastric biopsy in patients referred to Aras Clinique in Ardabil, northwest of Iran (2019-2021).

MATERIALS AND METHODS

In this descriptive-cross sectional study, 287 dyspeptic patients were included. For bacterial isolation, gastric biopsy specimens (n=287) were taken from gastric antrum, then aseptically were cultured on the selective medium and incubated at 37C in microaerophilic conditions for 3-5 days.

RESULTS

25.18% of all (n = 70) patients were found to be infected with H. pylori upon endoscopy. Of them, 9 patients (12.857%) and 2 patients (2.875%) had peptic ulcer disease and gastric cancer respectively. According to the different patterns of virulence factors, 57 virutypes were identified in which oipA-vacAs1-vacAm2 (3, 4.28% n =) and oipA-vacAs1-vacAs2-vacAm2 (3, 4.28% n =) were the most common patterns. The simultaneous presence of vacAS2, vacAm2 and hopQ2 genes was observed in both patients with gastric cancer. OipA (n = 562.5%), VacAs1 (n = 6.75%), VacAs2 (n = 6.75%), and VacAm2 (n = 787.5%) were found to be the most prevalent virulence factor.

CONCLUSION

According previous studies, it is confirmed that the cagPAI gene cluster and vacA gene alleles are strongly correlated with gastritis and gastrointestinal tract adenocarcinomas. Our study indicated that 50% of the indigenous strains of H. pylori harbor these oncogenic genes and they are hypervirulent.

There Are No Insurmountable Barriers: Passage of the Helicobacter pylori VacA Toxin from Bacterial Cytoplasm to Eukaryotic Cell Organelle

The Gram-negative bacterium Helicobacter pylori is a very successful pathogen, one of the most commonly identified causes of bacterial infections in humans worldwide. H. pylori produces several virulence factors that contribute to its persistence in the hostile host habitat and to its pathogenicity. The most extensively studied are cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA). VacA is present in almost all H. pylori strains. As a secreted multifunctional toxin, it assists bacterial colonization, survival, and proliferation during long-lasting infections. To exert its effect on gastric epithelium and other cell types, VacA undergoes several modifications and crosses multiple membrane barriers. Once inside the gastric epithelial cell, VacA disrupts many cellular-signaling pathways and processes, leading mainly to changes in the efflux of various ions, the depolarization of membrane potential, and perturbations in endocytic trafficking and mitochondrial function. The most notable effect of VacA is the formation of vacuole-like structures, which may lead to apoptosis. This review focuses on the processes involved in VacA secretion, processing, and entry into host cells, with a particular emphasis on the interaction of the mature toxin with host membranes and the formation of transmembrane pores.

A Genetic and Immunohistochemical Analysis of Helicobacter pylori Phenotypes and p27 Expression in Adenocarcinoma Patients in Jordan

Stomach (gastric) cancer is one of the most prevalent and deadly cancers worldwide and most gastric cancers are adenocarcinomas. Based on prior research, there is an association between Helicobacter pylori (H. pylori) infection together with the frequency of duodenal ulcer, distal gastric adenocarcinoma, mucosa-associated lymphoid tissue (MALT) lymphoma, and antral gastritis. Helicobacter pylori virulence and toxicity factors have been identified before that significantly influence the clinical outcomes of H. pylori infection and gastric adenocarcinoma. However, it remains unclear exactly how different strains of H. pylori affect gastric adenocarcinoma. Current research suggests this involves tumor suppressor genes, like p27 but also H. pylori toxic virulence proteins. Therefore, we quantified known H. pylori genotypes within adenocarcinoma patients to establish the prevalence of known toxins that include cytotoxin-associated gene A (cagA) as well as vacuolating cytotoxin A (vacA) within patients of variable adenocarcinoma diagnosis. This analysis used gastrectomy samples validated for DNA viability. The incidence of H. pylori in adenocarcinoma patients in Jordan was established to be 54.5% positive (ureA gene positive) with cagA genotype occurrence at 57.1%, but also in this population study vacA gene ratios found to be 24.7%:22.1%:14.3%:14.3%. (vacAs1:vacAs2:vacAm1:vacAm2). Using immunohistochemistry (IHC), we confirmed with statistical significance that p27 was dysregulated and suppressed, within nearly all H. pylori vacA genotypes. In addition, within 24.6% of H. pylori samples analyzed was a different bacterial genotype, and curiously that p27 protein expression was retained in 12% of tested adenocarcinoma H. pylori samples. This is suggestive that p27 could be used as a prognostic indicator but also that an unknown genotype could be contributing to the regulatory effects of p27 protein within this bacterial and cellular environment that may include other virulence factors and unknown immune system regulatory changes.

Helicobacter pylori and Its Role in Gastric Cancer

Gastric cancer is a challenging public health concern worldwide and remains a leading cause of cancer-related mortality. The primary risk factor implicated in gastric cancer development is infection with Helicobacter pylori. H. pylori induces chronic inflammation affecting the gastric epithelium, which can lead to DNA damage and the promotion of precancerous lesions. Disease manifestations associated with H. pylori are attributed to virulence factors with multiple activities, and its capacity to subvert host immunity. One of the most significant H. pylori virulence determinants is the cagPAI gene cluster, which encodes a type IV secretion system and the CagA toxin. This secretion system allows H. pylori to inject the CagA oncoprotein into host cells, causing multiple cellular perturbations. Despite the high prevalence of H. pylori infection, only a small percentage of affected individuals develop significant clinical outcomes, while most remain asymptomatic. Therefore, understanding how H. pylori triggers carcinogenesis and its immune evasion mechanisms is critical in preventing gastric cancer and mitigating the burden of this life-threatening disease. This review aims to provide an overview of our current understanding of H. pylori infection, its association with gastric cancer and other gastric diseases, and how it subverts the host immune system to establish persistent infection.

Biomarker Characterization and Prediction of Virulence and Antibiotic Resistance from Helicobacter pylori Next Generation Sequencing Data

The Gram-negative bacterium Helicobacter pylori colonizes c.a. 50% of human stomachs worldwide and is the major risk factor for gastric adenocarcinoma. Its high genetic variability makes it difficult to identify biomarkers of early stages of infection that can reliably predict its outcome. Moreover, the increasing antibiotic resistance found in H. pylori defies therapy, constituting a major human health problem. Here, we review H. pylori virulence factors and genes involved in antibiotic resistance, as well as the technologies currently used for their detection. Furthermore, we show that next generation sequencing may lead to faster characterization of virulence factors and prediction of the antibiotic resistance profile, thus contributing to personalized treatment and management of H. pylori-associated infections. With this new approach, more and permanent data will be generated at a lower cost, opening the future to new applications for H. pylori biomarker identification and antibiotic resistance prediction.

Interplay and cooperation of Helicobacter pylori and gut microbiota in gastric carcinogenesis

Chronic Helicobacter pylori infection is a critical risk factor for gastric cancer (GC). However, only 1–3 % of people with H. pylori develop GC. In gastric carcinogenesis, non-H. pylori bacteria in the stomach might interact with H. pylori. Bacterial dysbiosis in the stomach can strengthen gastric neoplasia development via generating tumor-promoting metabolites, DNA damaging, suppressing antitumor immunity, and activating oncogenic signaling pathways. Other bacterial species may generate short-chain fatty acids like butyrate that may inhibit carcinogenesis and inflammation in the human stomach. The present article aimed at providing a comprehensive overview of the effects of gut microbiota and H. pylori on the development of GC. Next, the potential mechanisms of intestinal microbiota were discussed in gastric carcinogenesis. We also disserted the complicated interactions between H. pylori, intestinal microbiota, and host in gastric carcinogenesis, thus helping us to design new strategies for preventing, diagnosing, and treating GC.

Relationship between weight gain and survival rate in patients with metastatic lung cancer

Background: Lung cancer accounts for about 13% of all cancers and about 60% of patients with lung cancer also experience weight loss during treatment. There seems to be a clear correlation between the therapeutic outcomes of patients based on their weight changes during treatment. The aim of this study was to investigate the relationship between weight changes during and after treatment and the therapeutic outcomes of a patient with metastatic lung cancer.

Methods: This cohort study was performed on patients with the diagnosis of non-surgical metastatic lung cancer referred to Hematology and Oncology Clinic, Rasoul-e-Akram Hospital. Patients were divided into two groups with a weight gain of more than 5% and a weight gain of 5% and less. The information was entered into the SPSS version 21 software. In the descriptive analysis, mean and standard deviation (SD) were used. To compare quantitative variables, independent samples t-test, Mann-Whitney, chi-square or Fisher exact tests were used to compare qualitative variables and correlation test was used to determine the correlation between quantitative data. Survival curves were used to show differences in two groups of studies. A regression model was used to calculate the hazard ratio. The significance level was less than 0.05.

Results: Sixty patients, including 40 males (66.7%) and 20 females (33.3%) were studied. The mean age of patients was 62.22±9.00 years (43-83 years). The mean weight changes in the patients were -1.28±6.11 kg (-16 to 16kg). Forty-seven patients (78.3%) had weight gain less than 5%. There was no significant difference in overall survival (OS) and progression-free survival (PFS) according to weight gain.

Conclusion: Finally, the findings of the study showed that, despite the fact that PFS and OS in the weight gain group were greater than 5% of the original weight; the difference was not statistically significant.

Contrasting association of Helicobacter pylori oipA genotype with risk of peptic ulceration and gastric cancer

Helicobacter pylori OipA (outer inflammatory protein A) is an outer membrane protein that involves in the binding and colonization of the bacterium in the stomach. The oipA status is associated with the risk of peptic ulcerations (PUs) and gastric cancer (GC) diseases. However, the association trend with PUs compared to GC is often different and highly challenging. We therefore aimed to determine the presence of this genotype in Iranian strains and assess its association with the risk of PUs and GC in a larger number of samples. A total of 319 strains were obtained from 172 patients with non-atrophic gastritis (NAG), 52 with PUs and 95 with GC. The prevalence of the oipA⁺vs. oipA^- genotype was 67.7% (216/319). The total frequency of the oipA⁺vs. oipA^- genotypes in NAG, PUs, GC, non-peptic ulceration (including NAG and GC), and non-tumor (including NAG and PUs) groups was 121/172 (70.3%), 50/52 (96.2%), 45/95 (47.4%), 166/267 (62.2%), and 171/224 (76.3%), respectively. In multiple logistic regression analysis, the oipA⁺vs. oipA^- genotype showed a strong direct association with PUs; the OR_adj (95% CI) was 18.751 (4.421-79.531), (p = 0.00007). In contrast, it had a significant reverse association with GC; the OR_adj (95% CI) was 0.330 (0.179-0.607), (p = 0.00036). In the present study, we interestingly found a contrasting association of the H. pylori oipA genotype with the risk of PUs and GC in Iran. Therefore, the contrasting effect of this genotype may emphasize its independent role in predicting clinical outcomes.

New genotypes of Helicobacter Pylori VacA d-region identified from global strains

BACKGROUND

Pathogenesis of Helicobacter Pylori (HP) vacuolating toxin A (vacA) depends on polymorphic diversity within the signal (s), middle (m), intermediate (i), deletion (d) and c-regions. These regions show distinct allelic diversity. The s-region, m-region and the c-region (a 15 bp deletion at the 3'-end region of the p55 domain of the vacA gene) exist as 2 types (s1, s2, m1, m2, c1 and c2), while the i-region has 3 allelic types (i1, i2 and i3). The locus of d-region of the vacA gene has also been classified into 2 genotypes, namely d1 and d2. We investigated the "d-region"/"loop region" through bioinformatics, to predict its properties and relation to disease. One thousand two hundred fifty-nine strains from the NCBI nucleotide database and the dryad database with complete vacA sequences were included in the study. The sequences were aligned using BioEdit and analyzed using Lasergene and BLAST. The secondary structure and physicochemical properties of the region were predicted using PredictProtein.

RESULTS

We identified 31 highly polymorphic genotypes in the "d-region", with a mean length of 34 amino acids (9 ~ 55 amino acids). We further classified the 31 genotypes into 3 main types, namely K-type (strains starting with the KDKP motif in the "d-region"), Q-type (strains starting with the KNQT motif), and E-type (strains starting with the ESKT motif) respectively. The most common type, K-type, is more prevalent in cancer patients (80.87%) and is associated with the s1i1m1c1 genotypes (P < .01). Incidentally, a new region expressing sequence diversity (2 aa deletion) at the C-terminus of the p55 domain of vacA was identified during bioinformatics analysis.

CONCLUSIONS

Prediction of secondary structures shows that the "d-region" adopts a loop conformation and is a disordered region.

Helicobacter pylori Virulence Factors-Mechanisms of Bacterial Pathogenicity in the Gastric Microenvironment

Gastric cancer constitutes one of the most prevalent malignancies in both sexes; it is currently the fourth major cause of cancer-related deaths worldwide. The pathogenesis of gastric cancer is associated with the interaction between genetic and environmental factors, among which infection by Helicobacter pylori (H. pylori) is of major importance. The invasion, survival, colonization, and stimulation of further inflammation within the gastric mucosa are possible due to several evasive mechanisms induced by the virulence factors that are expressed by the bacterium. The knowledge concerning the mechanisms of H. pylori pathogenicity is crucial to ameliorate eradication strategies preventing the possible induction of carcinogenesis. This review highlights the current state of knowledge and the most recent findings regarding H. pylori virulence factors and their relationship with gastric premalignant lesions and further carcinogenesis.

Is there a relationship between Helicobacter pylori vacA i1 or i2 alleles and development into peptic ulcer and gastric cancer? A meta-analysis study on an Iranian population

Helicobacter pylori has several virulance factor i.e. VacA, CagA, BabA, SabA, AlpA, AlpB and etc. VacA has several polymorphic region in the nucleotide sequence such as s,m,i,d and, c. It has been suggested that each variation in these polymorphic region has been influenced the toxicity of VacA toxin. We performed a comprehensive meta-analysis to determine the main role of VacAi1/i2 in development into peptic ulcer and gastric cancer in an Iranian population.

Role of vacuolating cytotoxin A in Helicobacter pylori infection and its impact on gastric pathogenesis

Introduction Helicobacter pylori causes, via the influence of several virulence factors, persistent infection of the stomach, which leads to severe complications. Vacuolating cytotoxin A (VacA) is observed in almost all clinical strains of H. pylori; however, only some strains produce the toxigenic and pathogenic VacA, which is influenced by the gene sequence variations. VacA exerts its action by causing cell vacuolation and apoptosis. We performed a PubMed search to review the latest literatures published in English language. Areas covered Articles regarding H. pylori VacA and its genotypes, architecture, internalization, and role in gastric infection and pathogenicity are reviewed. We included the search for recently published literature until January 2020. Expert opinion H. pylori VacA plays a crucial role in severe gastric pathogenicity. In addition, VacA mediated in vivo bacterial survival leads to persistent infection and an enhanced bacterial evasion from the action of antibiotics and the innate host defense system, which leads to drug evasion. VacA as a co-stimulator for the CagA phosphorylation may exert a synergistic effect playing an important role in the CagA-mediated pathogenicity.

Helicobacter pylori-related risk predictors of gastric cancer: The latest models, challenges, and future prospects

Helicobacter pylori is known as an important determinant of preneoplastic lesions or gastric cancer (GC) risk. The bacterial genotypes may determine the clinical outcomes. However, the evidence for these associations has varied between and within continents, and the actual effect of each gene and corresponding allelic variants are still debatable. In recent years, two new models have been proposed to predict the risk of GC; the phylogeographic origin of H. pylori strains and a disrupted co-evolution between H. pylori and its human host, which potentially explain the geographic differences in the risk of H. pylori-related cancer. However, these models and earlier ones based on putative virulence factors of the bacterium may not fully justify differences in the incidence of GC, reflecting that new theories should be developed and examined. Notably, the new findings also support the role of ancestry-specific germline alteration in contributing to the ethnic/population differences in cancer risk. Moreover the high and low incidence areas of GC have shown differences in transmission ecology, largely affecting the composition of H. pylori populations. As a new hypothesis, it is proposed that any high-risk population may have its own specific risk loci (or variants) as well as new H. pylori strains with national/maybe regional gene pools that should be considered. The latter is seen in the Americas where the rapid evolution of distinct H. pylori subpopulations has been occurred. It is therefore proposed that the deep sequencing of both H. pylori and its human host is simultaneously performed in GC patients and age-sex-matched controls from high-risk areas. The expression and functional activities of the identified new determinants of GC must then be assessed and matched with human and pathogen ancestry, because some of risk loci are ancestry-specific. In addition, potential study-level covariates and moderator variables (eg physical conditions, life styles, gastric microbiome, etc) linked to causal relationships, and their impact, should be recognized and controlled.

Mechanisms of the Epithelial-Mesenchymal Transition and Tumor Microenvironment in Helicobacter pylori-Induced Gastric Cancer

Helicobacter pylori (H. pylori) is one of the most common human pathogens, affecting half of the world’s population. Approximately 20% of the infected patients develop gastric ulcers or neoplastic changes in the gastric stroma. An infection also leads to the progression of epithelial–mesenchymal transition within gastric tissue, increasing the probability of gastric cancer development. This paper aims to review the role of H. pylori and its virulence factors in epithelial–mesenchymal transition associated with malignant transformation within the gastric stroma. The reviewed factors included: CagA (cytotoxin-associated gene A) along with induction of cancer stem-cell properties and interaction with YAP (Yes-associated protein pathway), tumor necrosis factor α-inducing protein, Lpp20 lipoprotein, Afadin protein, penicillin-binding protein 1A, microRNA-29a-3p, programmed cell death protein 4, lysosomal-associated protein transmembrane 4β, cancer-associated fibroblasts, heparin-binding epidermal growth factor (HB-EGF), matrix metalloproteinase-7 (MMP-7), and cancer stem cells (CSCs). The review summarizes the most recent findings, providing insight into potential molecular targets and new treatment strategies for gastric cancer.

Precancerous Gastric Lesions with Helicobacter pylori vacA +/babA2+/oipA + Genotype Increase the Risk of Gastric Cancer

Objective

The clinical outcomes of gastric diseases such as chronic gastritis, peptic ulcer, and gastric cancer have been attributed to the interplay of virulence factors of Helicobacter pylori (H. pylori), host genetic susceptibility, and host immune responses. This study investigated the presence of cagA, vacA, iceA2, babA2, and oipA genes and their association with clinical outcomes.

Methods

Chronic gastritis, atrophic gastritis, and intestinal metaplasia specimens were obtained from patients who underwent endoscopy and surgical resection between January 2017 and December 2018; specimens from gastric cancer patients treated between January 2014 and December 2018 were also added. H. pylori), host genetic susceptibility, and host immune responses. This study investigated the presence of cagA, vacA, iceA2, babA2, and oipA genes and their association with clinical outcomes. H. pylori), host genetic susceptibility, and host immune responses. This study investigated the presence of

Results

H. pylori), host genetic susceptibility, and host immune responses. This study investigated the presence of vacA, babA2, and oipA genes and their association with clinical outcomes. vacA, babA2, and oipA genes and their association with clinical outcomes. P=0.033, OR = 2.64; 95% CI = 1.44–4.82, P=0.033, OR = 2.64; 95% CI = 1.44–4.82, P=0.033, OR = 2.64; 95% CI = 1.44–4.82, H. pylori vacA⁺/babA2, and oipA genes and their association with clinical outcomes. P=0.033, OR = 2.64; 95% CI = 1.44–4.82,

Conclusion

In this present study, we reported on the virulence genes of H. pylori infection to reveal their association with increased risk of chronic gastritis, precancerous gastric lesions, and gastric cancer. Precancerous gastric lesions with H. pylori vacA+/babA2+/oipA+ genotype increased the risk of gastric cancer.H. pylori), host genetic susceptibility, and host immune responses. This study investigated the presence of H. pylori vacA⁺/babA2, and oipA genes and their association with clinical outcomes.

Unique constellations of five polymorphic sites of Helicobacter pylori vacA and cagA status associated with risk of gastric cancer

Helicobacter pylori possesses virulence genes that are involved in the pathogenesis of the bacterium. There are little data regarding all constellations of five polymorphic sites of H. pylori vacA and cagA status. We therefore aimed to i) find any associations between H. pylori vacA alleles (s1/s2, m1/m2, i1/i2, d1/d2, and c1/c2) and cagA status and ii) determine the frequency of all five-genotype combinations of the vacA alleles with and without cagA gene, and their associations with risk of gastric cancer (GC). A total of 290 Iranian H. pylori isolates from gastrointestinal patients were obtained successfully by the cultivation of biopsies and genotyped. The patients included 144/290 with non-atrophic gastritis (NAG), 57/290 with peptic ulcer disease (PUD), and 89/290 with GC. We found that each of the vacA m1-, i1-, d1-, and c1-genotypes was significantly associated with cagA⁺ status. The odds ratio(OR) and 95% confidence interval (95% CI) was 2.316 (1.241-4.301) for cagA⁺/vacA m1, 2.764 (1.540-4.960) for cagA⁺/vacA i1, 4.288 (2.305-7.977) for cagA⁺/vacA d1, and 2.639 (1.488-4.680) for cagA⁺/vacA c1, respectively. In this study, 43 five- and six-genotype combinations were found among 224 strains. The highest frequencies were observed for vacA s1m2i2d2c2 (85/224, 37.9%), s1m2i2d2c2/cagA (48/222, 21.6%), s1m1i1d1c1 (40/224, 17.9%) and s1m1i1d1c1/cagA (35/222, 15.8%). Logistic regression analysis showed that vacA s1m1i1d1c1, s1m2i1d2c1, s1m2i2d2c1, and s1m2i2d2c1/cagA had a high prevalence in GC patients compared to non-atrophic gastritis patients (p < .05). The ORs and 95% CI were 2.433 (1.070-5.531), 11.524 (1.253-106.023), 4.200 (1.261-13.993), and 6.263 (1.494-26.256), respectively. These results were also confirmed when the controls were non-tumors (NAG/PUD). We found novel five- and six-genotype combinations associated with the risk of GC. These associations seem to be strongly dependent on the presence of c1-type of vacA. Therefore, analysis of all combined genotypes of the vacA alleles and cagA status may play a significant role in determining H. pylori-related clinical outcomes.

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.

Are Helicobacter pylori highly cytotoxic genotypes and cardia gastric adenocarcinoma linked? Lessons from Iran

BACKGROUND

Although the most extensive studies revealed the role of H. pylori VacA and CagA toxins in the development of gastric adenocarcinoma, the magnitude of this association and the correlations of vacA mosaicism and cagA status with cardia gastric adenocarcinoma (CGA) still remain controversial.

OBJECTIVE

We aimed to examine the linkage of H. pylori highly cytotoxic genotypes to CGA in Iranian populations as a model.

METHODS

A total of 601 Iranian patients were enrolled. Biopsies were cultured, genotyped, and anatomically and histologically classified.

RESULTS

The vacA c1 genotype, but not cagA status, showed a strong association with the risk of both CGA and non-cardia adenocarcinoma (NCGA), whether the controls were non-tumors, as those with either non-atrophic gastritis or peptic ulcerations, (the OR (95%CI) was 14.11 (4.91-40.52) and 9.59 (4.06-22.65), respectively) or those with NAG (the OR (95%CI) was 10.71 (3.49-32.82) and 8.11 (3.26-20.16), respectively). The vacA c1/cagA+ genotype was significantly associated with an increased risk of NCGA, whether the controls were non-tumors or those with NAG; the adjusted risk was 4.706 (1.41-15.67) and 4.85 (1.42-16.51), respectively.

CONCLUSIONS

The H. pylori vacA c1 genotype, but not cagA status, might be the first important bacterial biomarker for predicting the cardia adenocarcinoma risk in male patients aged ⩾ 55 in Iran.

Genetic populations and virulence factors of Helicobacter pylori

Helicobacter pylori is a bacterium that has infected more than half of the human population worldwide. This bacterium is closely associated with serious human diseases, such as gastric cancer, and identifying and understanding factors that predict bacterial virulence is a priority. In addition, this pathogen shows high genetic diversity and co-evolution with human hosts. H. pylori population genetics, therefore, has emerged as a tool to track human demographic history. As the number of genome sequences available is increasing, studies on the evolution and virulence of H. pylori are gaining momentum. This review article summarizes the most recent findings on H. pylori virulence factors and population genetics.

Prevalence, risk factors, and virulence genes of Helicobacter pylori among dyspeptic patients in two different gastric cancer risk regions of Thailand

Gastric cancer risk is varied among different regions of Thailand. We examined the characteristics of Helicobacter pylori infection in two regions of Thailand. The H. pylori status of 273 dyspeptic patients (136 from the South and 137 from the North; a low and high incidence of gastric cancer region, respectively) was evaluated, and virulence genotypes (cagA, vacA, hrgA and jhp0562-positive/β-(1,3)galT) were determined. The overall H. pylori infection rate was 34.1% (93/273). The prevalence was higher in the North than in the South (50.4% vs. 17.6%, P <0.001) and was significantly higher among individuals with the following characteristics: low income, birthplace in the Northeast or North regions, agricultural employment, or consumption of alcohol or unboiling water. Among these socio-demographic determinants, region was an independent risk factor for H. pylori infection (odds ratio = 6.37). Patients including both H. pylori infected and uninfected cases who lived in the North had significantly more severe histological scores than those in the South. In contrast, among H. pylori-positive cases, patients in the South had significantly more severe histological scores than those in the North. Of the 74 strains cultured, 56.8% carried Western-type cagA, with a higher proportion in the South than in the North (76.2% vs. 49.1%, P = 0.05). In disagreement with the current consensus, patients infected with the Western-type cagA strains had more severe inflammation scores in the antrum than those infected with the East Asian-type cagA strains (P = 0.027). Moreover, Western-type cagA strains induced more severe histological scores in patients from the South than those of either genotype from the North. Other virulence genes had no influence on histological scores. The incidence of gastric cancer in Thailand was different among regions and corresponded to differences in the prevalence of H. pylori infection. More careful follow-up for patients in the South will be required, even if they are infected with H. pylori carrying Western-type cagA.

Helicobacter pylori virulence genes of minor ethnic groups in North Thailand

Background

There are few studies analyzed concurrently the prevalence and genotypes of Helicobacter pylori infection with the ancestor origins from different ethnics, especially with including minority groups. We recruited a total of 289 patients in MaeSot, Thailand (154 Thai, 14 Thai-Chinese, 29 Karen and 92 Hmong ethnics). The virulence genes and genealogy of the strains were determined by PCR-based sequencing.

Results

Based on culture and histology/immunohistochemistry, the prevalence of H. pylori infection was 54.5% (158/289). Among 152 isolates cultured, the East-Asian-type cagA was predominant genotype among strains from Hmong, Thai-Chinese and Thai (96.0% [48/50], 85.7% [6/7] and 62.7% [47/75], respectively), whilst majority of strains from Karen had Western-type cagA (73.3% [11/15]). Patients infected with the East-Asian-type cagA strains had significantly higher activity and intestinal metaplasia in the antrum and activity in the corpus than those with Western-type cagA (P = 0.024, 0.006 and 0.005, respectively). The multilocus sequencing typing analysis discriminated that most strains from Hmong and Thai-Chinese belonged to hspEAsia (92.0 and 85.7%, respectively), whereas strains from Karen predominantly possessed hpAsia2 (86.7%) and strains from Thai were classified into hspEAsia (45.2%) and hpAsia2 (31.1%).

Conclusions

Helicobacter pylori genotypes were relatively different among ethnic groups in Thailand and were associated with the source of ancestor even living in a small rural town. Caution and careful check-up are required especially on Hmong ethnic associated with high prevalence of virulence genotypes of H. pylori.

Electronic supplementary material

The online version of this article (doi:10.1186/s13099-017-0205-x) contains supplementary material, which is available to authorized users.

Helicobacter pylori outer inflammatory protein A (OipA) suppresses apoptosis of AGS gastric cells in vitro

Outer inflammatory protein A (OipA) is an important virulence factor associated with gastric cancer and ulcer development; however, the results have not been well established and turned out to be controversial. This study aims to elucidate the role of OipA in Helicobacter pylori infection using clinical strains harbouring oipA "on" and "off" motifs. Proteomics analysis was performed on AGS cell pre-infection and postinfection with H. pylori oipA "on" and "off" strains, using liquid chromatography/mass spectrometry. AGS apoptosis and cell cycle assays were performed. Moreover, expression of vacuolating cytotoxin A (VacA) was screened using Western blotting. AGS proteins that have been suggested previously to play a role or associated with gastric disease were down-regulated postinfection with oipA "off" strains comparing to oipA "on" strains. Furthermore, oipA "off" and ΔoipA cause higher level of AGS cells apoptosis and G0/G1 cell-cycle arrest than oipA "on" strains. Interestingly, deletion of oipA increased bacterial VacA production. The capability of H. pylori to induce apoptosis and suppress expression of proteins having roles in human disease in the absence of oipA suggests that strains not expressing OipA may be less virulent or may even be protective against carcinogenesis compared those expressing OipA. This potentially explains the higher incidence of gastric cancer in East Asia where oipA "on" strains predominates.

Two populations of less-virulent Helicobacter pylori genotypes in Bangladesh

Bangladesh has a population with a low gastric cancer risk but high prevalence of Helicobacter pylori infection. Several studies have examined virulence genes in H. pylori from Bangladesh. We analyzed cagA and vacA subtypes and their association with severe histology phenotypes, and analyzed population types among Bangladeshi strains. We included patients who underwent endoscopy in Dhaka. Sequences of virulence genes and seven housekeeping genes were obtained by next generation sequencing and confirmed by Sanger sequencing. We isolated 56 H. pylori strains from 133 patients, of which 73.2% carried cagA, and all were considered Western-type. Patients infected with cagA-positive strains had more severe histological scores than patients infected with cagA-negative strains. Among vacA s1 and m1 genotypes, the s1a (97.8%, 43/44) and m1c (28/30, 93.3%) genotypes were predominant. All strains containing s1 and m1 (30/56, 53.6%) also had i1, d1, and c1. In contrast, all strains containing the less-virulent genotypes s2 and m2 (12/56, 21.4%) also possessed i2, d2, and c2. Multivariate analysis indicated that subjects infected with vacA m1-genotype strains only had a significantly higher risk of antrum atrophy than patients infected with m2-genotype strains. Of the two main H. pylori populations in this study, hpAsia2 strains were associated with higher activity and inflammation in the antrum compared to hpEurope strains; however, only vacA s1m1i1d1c1 strains, independent of population type, were significantly associated with inflammation in the antrum, unlike the s2m2i2d2c2 genotype. In conclusion, Bangladeshi strains were divided into two main populations of different genotypes. The low incidence of gastric cancer in Bangladesh might be attributable to the high proportion of less-virulent genotypes, which may be a better predictor of gastric cancer risk than the ancestral origin of the H. pylori strains. Finally, the vacA m region may be a better virulence marker than other regions.

Helicobacter pylori genotypes determine risk of non-cardia gastric cancer and intestinal- or diffuse-type GC in Ardabil: A very high-risk area in Northwestern Iran

Frequency of the Helicobacter pylori vacA gene polymorphism and its association with gastric cancer (GC) was assessed in Ardabil, a very high-risk area in Northwestern Iran. We determined the presence of the H. pylori 16S rDNA gene and the vacA s-, m-, i-, and d-region genotypes in DNA from fresh gastric biopsies. Patients with GC were classified based on both the anatomic site and the histopathologic type of tumor Of 135 patients, including 57 with non-atrophic gastritis (NAG) and 78 with GC, 103 were infected by H. pylori. The vacA i1 and d1 genotypes were significantly linked to an increased risk of GC, where both cardia (CGC) and non-cardia GC (NCGC) patients were entered into the analysis. The adjusted OR was 9.59 for i1 and 4.39 for d1. Furthermore, i1 was significantly linked to an increased risk of the intestinal-type adenocarcinoma (OR = 14.04) and d1 to the risk of the diffuse-type adenocarcinoma (OR = 7.71). The presence of the m1-type of vacA in combination with i1 or d1 further increased the risk of GC. When the analysis was restricted to NCGC, the adjusted OR for i1 and d1, was 37.52 and 7.17, respectively. No significant association was found between genotypes and the risk of GC in the cardia site of the stomach. It is proposed that the new types of H. pylori vacA, i1 and d1, might be important determinants of NCGC risk in Ardabil. The m1, not independently, but in combination might further define the risk of GC. i1and d1 might also predict the risk of the intestinal- and diffuse-type adenocarcinomas, respectively.

Helicobacter pylori as an oncogenic pathogen, revisited

Gastric cancer is an inflammation-associated malignancy aetiologically related to infection with the bacterium, Helicobacter pylori, which is considered a necessary but insufficient cause. Unless treated, H. pylori causes life-long acute and chronic gastric inflammation resulting in progressive gastric mucosal damage that may result in gastric cancer. The rate of progression from superficial gastritis, to an atrophic metaplastic mucosa, and ultimately to cancer relates to the virulence of the infecting H. pylori as well as host and environmental factors. H. pylori virulence is a reflection of its propensity to cause severe gastric inflammation. Both mucosal inflammation and H. pylori can cause host genomic instability, including dysregulation of DNA mismatch repair, stimulation of expression of activation-induced cytidine deaminase, abnormal DNA methylation and dysregulation of  micro RNAs, which may result in an accumulation of mutations and loss of normal regulation of cell growth. The difference in cancer risk between the most and least virulent H. pylori strain is only approximately 2-fold. Overall, none of the putative virulence factors identified to date have proved to be disease-specific. The presence, severity, extent and duration of inflammation appear to be the most important factors and current evidence suggests that any host, environmental or bacterial factor that reliably enhances the inflammatory response to the H. pylori infection increases the risk of gastric cancer.

Relationship between vacA Types and Development of Gastroduodenal Diseases

The Helicobacter pylori vacuolating cytotoxin (VacA) is a secreted pore-forming toxin and a major virulence factor in the pathogenesis of H. pylori infection. While VacA is present in almost all strains, only some forms are toxigenic and pathogenic. While vacA and its genotypes are considered as markers of H. pylori-related diseases or disorders, the pathophysiological mechanisms of VacA and its genotypes remain controversial. This review outlines key findings of publications regarding vacA with emphasis on the relationship between vacA genotypes and the development of human disease.