Effect of Helicobacter pylori on gastrointestinal microbiota: a population-based study in Linqu, a high-risk area of gastric cancer

Intracellular Presence of Helicobacter pylori and Its Virulence-Associated Genotypes within the Vaginal Yeast of Term Pregnant Women

BACKGROUND

Helicobacter pylori transmission routes are not entirely elucidated. Since yeasts are postulated to transmit this pathogen, this study aimed to detect and genotype intracellular H. pylori harbored within vaginal yeast cells.

METHODS

A questionnaire was used to determine risk factors of H. pylori infection. Samples were seeded on Sabouraud Dextrose Agar and horse blood-supplemented Columbia agar. Isolated yeasts were identified using and observed by optical microscopy searching for intra-yeast H. pylori. Total yeast DNA, from one random sample, was extracted to search for H. pylori virulence genes by PCR and bacterial identification by sequencing.

RESULTS

43% of samples contained yeasts, mainly Candida albicans (91%). Microscopy detected bacteria such as bodies and anti-H. pylori antibodies binding particles in 50% of the isolated yeasts. Total DNA extracted showed that 50% of the isolated yeasts were positive for H. pylori 16S rDNA and the sequence showed 99.8% similarity with H. pylori. In total, 32% of H. pylori DNA positive samples were cagA+ vacAs1a vacAm1 dupA-. No relationship was observed between possible H. pylori infection risk factors and vaginal yeasts harboring this bacterium.

CONCLUSION

H. pylori having virulent genotypes were detected within vaginal yeasts constituting a risk for vertical transmission of this pathogen.

Comparison of clinicopathological parameters, prognosis, micro-ecological environment and metabolic function of Gastric Cancer with or without Fusobacterium sp. Infection

Background: Fusobacterium sp. plays a crucial role in the tumorigenesis and development of gastrointestinal tumors. Our research group previously disclosed that Fusobacterium sp. was more abundant in gastric cancer (GC) tissues than adjacent non-cancerous (NC) tissues. However, Fusobacterium sp. did not exist in all GC tissues and the differentiated features of GC with or without Fusobacterium sp. infection is not clear.

Methods: The expression data of 61 GC tissues came from 16S rRNA gene sequencing. Comparison groups were defined based on sOTU at the genus level of Fusobacterium sp., which was performed by the Qiime2 microbiome bioinformatics platform. We used Chi-square and Fisher's exact test to compare clinicopathological parameters, and used Kaplan-Meier analysis, Cox univariate and multivariate analysis to compare prognosis. Micro-ecological environment comparison was characterized by 16S rRNA gene sequencing, and the metabolic function prediction was applied by PICRUSt2. Results of microbial diversity, differential enrichment genus and metabolic function in GC with or without Fusobacterium sp. infection was validated with 229 GC tissues downloaded from an independent cohort in ENA database (PRJNA428883).

Results: The infection rate of Fusobacterium sp. in 61 GC tissues was 52.46% and elderly GC patients were more prone to Fusobacterium sp. infection. GC patients infected with Fusobacterium sp. were more likely to have tumor-infiltrating lymphocytes and p53 expression. The microbial diversity and microbial structure showed significant differences between two GC tissue groups with 42 differential enrichment genera. The metabolic function of Fusobacterium sp.-positive GC tissues was related to the biosynthesis of lysine, peptidoglycan, and tRNA. The differences in microbial structure, the existence of some differential enrichment genera and the metabolic function of Fusobacterium sp.-positive GC tissues, were then validated by 229 GC tissues of an independent cohort.

Conclusions: Fusobacterium sp. infection can affect the phenotypic characteristics, micro-ecological environment, and metabolic functions of GC, which may provide a basis for further exploring the relationship between Fusobacterium sp. infection and carcinogenesis of GC.

Long-term persistence of gastric dysbiosis after eradication of Helicobacter pylori in patients who underwent endoscopic submucosal dissection for early gastric cancer

BACKGROUND

Gastric microbiome, other than Helicobacter pylori, plays a role in the tumorigenesis of gastric cancer (GC). Patients who undergo endoscopic submucosal dissection for early GC have a high risk of developing metachronous GC even after successful eradication of H. pylori. Thus, we investigated the microbial profiles and associated changes in such patients after the eradication of H. pylori.

METHODS

A total of 19 H. pylori-infected patients with early GC who were or to be treated by endoscopic resection, with paired biopsy samples at pre- and post-eradication therapy, were retrospectively enrolled. Ten H. pylori-negative patients were enrolled as controls. Biopsy samples were analyzed using 16S rRNA sequencing.

RESULTS

H. pylori-positive patients exhibited low richness and evenness of bacteria with the deletion of several genera, including Blautia, Ralstonia, Faecalibacterium, Methylobacterium, and Megamonas. H. pylori eradication partially restored microbial diversity, as assessed during a median follow-up at 13 months after eradication therapy. However, post-eradication patients had less diversity than that in the controls and possessed a lower abundance of the five genera mentioned above. The eradication of H. pylori also altered the bacterial composition, but not to the same extent as that in controls. The microbial communities could be clustered into three separate groups: H. pylori-negative, pre-eradication, and post-eradication.

CONCLUSION

Changes in dysbiosis may persist long after the eradication of H. pylori in patients with a history of GC. Dysbiosis may be involved in the development of both primary and metachronous GC after the eradication of H. pylori in such patients.

The interplay between Helicobacter pylori and gastrointestinal microbiota

The complex population of microbes in the human gastrointestinal (GI) tract interacts with itself and with the host, exerting a deep influence on health and disease development. The development of modern sequencing technology has enabled us to gain insight into GI microbes. Helicobacter pylori colonization significantly affects the gastric microenvironment, which in turn affects gastric microbiota and may be correlated with colonic microbiota changes. Crosstalk between H. pylori and GI commensal flora may play a role in H. pylori-related carcinogenicity and extragastric manifestations. We review current knowledge on how H. pylori shapes GI microbiota with a specific focus on its impact on the stomach and colon. We also review current evidence on colonic microbiota changes attributed to eradication therapy based on the clinical studies performed to date.

Helicobacter pylori eradication therapy to prevent gastric cancer: systematic review and meta-analysis

OBJECTIVES

Gastric cancer is strongly associated with Helicobacter pylori (H. pylori). We conducted a previous systematic review and meta-analysis that suggested eradication therapy reduced future incidence of gastric cancer, but effect size was uncertain, and there was no reduction in gastric cancer-related mortality. We updated this meta-analysis, as more data has accumulated. We also evaluated impact of eradication therapy on future risk of gastric cancer in patients having endoscopic mucosal resection for gastric neoplasia.

DESIGN

We searched the medical literature through February 2020 to identify randomised controlled trials (RCTs) examining effect of eradication therapy on subsequent occurrence of gastric cancer in healthy H. pylori-positive adults, and in H. pylori-positive patients with gastric neoplasia undergoing endoscopic mucosal resection. The control arm received placebo or no treatment. Follow-up was for ≥2 years. We estimated the relative risk (RR) number needed to treat (NNT), and evaluated the disability-adjusted life-years (DALYs) gained from screening from the meta-analysis.

RESULTS

We identified 10 RCTs, seven recruited 8323 healthy individuals, and three randomised 1841 patients with gastric neoplasia. In healthy individuals, eradication therapy reduced incidence of gastric cancer (RR=0.54; 95% CI 0.40 to 0.72, NNT=72), and reduced mortality from gastric cancer (RR=0.61; 95% CI 0.40 to 0.92, NNT=135), but did not affect all-cause mortality. These data suggest that 8 743 815 DALYs (95% CI 5 646 173 to 11 847 456) would be gained if population screening and treatment was implemented globally. In patients with gastric neoplasia, eradication therapy also reduced incidence of future gastric cancer (RR=0.49; 95% CI 0.34 to 0.70, NNT=21). Adverse events were incompletely reported.

CONCLUSION

There is moderate evidence to suggest that H. pylori eradication therapy reduces the incidence of gastric cancer in healthy individuals and patients with gastric neoplasia in East Asian countries. There also appears to be a reduction in gastric cancer-related mortality.

Screening and eradication of Helicobacter pylori for gastric cancer prevention: the Taipei global consensus

OBJECTIVE

A global consensus meeting was held to review current evidence and knowledge gaps and propose collaborative studies on population-wide screening and eradication of Helicobacter pylori for prevention of gastric cancer (GC).

METHODS

28 experts from 11 countries reviewed the evidence and modified the statements using the Delphi method, with consensus level predefined as ≥80% of agreement on each statement. The Grading of Recommendation Assessment, Development and Evaluation (GRADE) approach was followed.

RESULTS

Consensus was reached in 26 statements. At an individual level, eradication of H. pylori reduces the risk of GC in asymptomatic subjects and is recommended unless there are competing considerations. In cohorts of vulnerable subjects (eg, first-degree relatives of patients with GC), a screen-and-treat strategy is also beneficial. H. pylori eradication in patients with early GC after curative endoscopic resection reduces the risk of metachronous cancer and calls for a re-examination on the hypothesis of 'the point of no return'. At the general population level, the strategy of screen-and-treat for H. pylori infection is most cost-effective in young adults in regions with a high incidence of GC and is recommended preferably before the development of atrophic gastritis and intestinal metaplasia. However, such a strategy may still be effective in people aged over 50, and may be integrated or included into national healthcare priorities, such as colorectal cancer screening programmes, to optimise the resources. Reliable locally effective regimens based on the principles of antibiotic stewardship are recommended. Subjects at higher risk of GC, such as those with advanced gastric atrophy or intestinal metaplasia, should receive surveillance endoscopy after eradication of H. pylori.

CONCLUSION

Evidence supports the proposal that eradication therapy should be offered to all individuals infected with H. pylori. Vulnerable subjects should be tested, and treated if the test is positive. Mass screening and eradication of H. pylori should be considered in populations at higher risk of GC.

Helicobacter pylori infection and eradication: Exploring their impacts on the gastrointestinal microbiota

The rapid development of microbiota research has remolded our view of human physiological and pathological processes. Among all the gastrointestinal microorganisms, Helicobacter pylori (H pylori) is probably the most notorious constituent. Although half of the adults worldwide are infected with H pylori, their clinical manifestations vary widely, suggesting other microorganisms beyond H pylori may play a role in determining clinical outcomes. Recently, many studies have put effort into elucidating the crosstalk within the human microbiota, some of which specifically explored the interplay between H pylori and other gastrointestinal microbial members. In this work, we reviewed these potential interactions. Meanwhile, the impacts of H pylori eradication therapy on gastrointestinal microbial homeostasis were summarized in terms of diversity, composition, functional capacity, and antibiotic resistance.

Efficacy of quadruple regimen with polaprezinc for gastric Helicobacter pylori infection eradication: protocol for a single-centre, single-blind, non-inferiority, randomised clinical trial

INTRODUCTION

Helicobacter pylori (H. pylori) is the most well-known risk factor for gastric cancer. At present, H. pylori shows varying levels of resistance to different treatments, leading to a lower rate of H. pylori eradication. The aim of this study is to evaluate the efficacy of polaprezinc-containing quadruple therapy (PQT) for the eradication of H. pylori infection and, thus, to provide more evidence to inform the clinical treatment of H. pylori infection in China.

METHODS AND ANALYSIS

This is a single-centre, single-blind, non-inferiority, randomised controlled trial, enrolling 158 patients with H. pylori infection. Patients are randomised (1:1) to the two groups for a 14-day therapy. Treatment group: PQT (esomeprazole 20 mg, amoxicillin 1 g, clarithromycin 500 mg, polaprezinc 75 mg) two times per day; control group: bismuth-containing quadruple therapy (esomeprazole 20 mg, amoxicillin 1 g, clarithromycin 500 mg, bismuth potassium citrate 220 mg) two times per day. The primary outcome is the rate of H. pylori eradication. Secondary outcomes are the incidence of adverse events and the gastrointestinal microbiota distribution. The 16S ribosomal RNA (16S rRNA) next-generation sequencing (NGS) is used to evaluate the effect of two different therapies on the distribution of the gastrointestinal microbiota.

ETHICS AND DISSEMINATION

This study was approved by the Ethics Committee of Sichuan Cancer Center & Hospital (No. SCCHEC-02-2019-015). Any amendment to the research protocol will be submitted for ethical approval. All participants must provide informed consent. On completion, the results of the study will be published in the appropriate peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ChiCTR1900025800; preresults.

MALDI-TOF MS and 16S RNA Identification of Culturable Gastric Microbiota: Variability Associated with the Presence of Helicobacter pylori

Helicobacter pylori is the main bacteria associated with gastroduodenal diseases. Recent studies have reported that gastric microbiota might be modified by the H. pylori colonization, favoring gastric lesions′ development. In Chile, the region of La Araucanía concentrates a high risk of gastric cancer associated with Helicobacter pylori colonization, rurality, poverty, and Mapuche ethnicity. Hence, we aimed to identify the culturable gastric microbiota and characterize its variability at different stages of epithelial injury, based on its H. pylori colonization in dyspeptic patients from this Chilean region. Microaerophilic bacteria strains were isolated from antrum biopsies of 155 dyspeptic patients′ biopsies and identified using MALDI-TOF MS or 16sRNA gene sequencing for non-pylori species identification, and UreC gene amplification for H. pylori confirmation. We found 48 species from 18 families, mainly belonging to Neisseriaceae (21.3%), Streptococcaceae (20.0%), Actynomicetaceae (9.0%), Enterobacteriaceae, and Lactobacillaceae (4.5%); however, Streptococcaceae and Actinomycetaceae families showed a significant reduction in samples infected with H. pylori, along with a considerably lower diversity of species. Our results revealed a microbiota modification due to H. pylori colonization associated with the gastric epithelial state, suggesting a potential microbiota role for developing and progressing gastric diseases.

Association of Combined Sero-Positivity to Helicobacter pylori and Streptococcus gallolyticus with Risk of Colorectal Cancer

Previously, we found that risk of colorectal cancer (CRC) is increased in individuals with serum antibody response to both Helicobacter pylori (HP) Vacuolating Cytotoxin (VacA) toxin or Streptococcus gallolyticus (SGG) pilus protein Gallo2178. In the present analysis, we tested the hypothesis that combined seropositivity to both antigens is a better indicator of CRC risk than seropositivity to single antigens. We used multiplex serologic assays to analyze pre-diagnostic serum for antibody responses from 4063 incident CRC cases and 4063 matched controls from 10 US cohorts. To examine whether combined SGG Gallo2178 and HP VacA sero-status was associated with CRC risk, we used conditional logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Compared to dual sero-negative individuals, there was no increased risk for individuals sero-positive to SGG Gallo2178 only (OR: 0.93; 95% CI: 0.66–1.31) or to HP VacA only (OR: 1.08; 95% CI: 0.98–1.19). However, dual sero-positive individuals had a >50% increased odds of developing CRC (OR: 1.54; 95% CI: 1.16–2.04), suggesting an interaction between antibody responses to these two pathogens and CRC risk (p_interaction = 0.06). In conclusion, this study suggests that dual sero-positivity to HP VacA and SGG Gallo2178 is an indicator of increased risk of CRC.

Pathways of Gastric Carcinogenesis, Helicobacter pylori Virulence and Interactions with Antioxidant Systems, Vitamin C and Phytochemicals

Helicobacter pylori is a class one carcinogen which causes chronic atrophic gastritis, gastric intestinal metaplasia, dysplasia and adenocarcinoma. The mechanisms by which H. pylori interacts with other risk and protective factors, particularly vitamin C in gastric carcinogenesis are complex. Gastric carcinogenesis includes metabolic, environmental, epigenetic, genomic, infective, inflammatory and oncogenic pathways. The molecular classification of gastric cancer subtypes has revolutionized the understanding of gastric carcinogenesis. This includes the tumour microenvironment, germline mutations, and the role of Helicobacter pylori bacteria, Epstein Barr virus and epigenetics in somatic mutations. There is evidence that ascorbic acid, phytochemicals and endogenous antioxidant systems can modify the risk of gastric cancer. Gastric juice ascorbate levels depend on dietary intake of ascorbic acid but can also be decreased by H. pylori infection, H. pylori CagA secretion, tobacco smoking, achlorhydria and chronic atrophic gastritis. Ascorbic acid may be protective against gastric cancer by its antioxidant effect in gastric cytoprotection, regenerating active vitamin E and glutathione, inhibiting endogenous N-nitrosation, reducing toxic effects of ingested nitrosodimethylamines and heterocyclic amines, and preventing H. pylori infection. The effectiveness of such cytoprotection is related to H. pylori strain virulence, particularly CagA expression. The role of vitamin C in epigenetic reprogramming in gastric cancer is still evolving. Other factors in conjunction with vitamin C also play a role in gastric carcinogenesis. Eradication of H. pylori may lead to recovery of vitamin C secretion by gastric epithelium and enable regression of premalignant gastric lesions, thereby interrupting the Correa cascade of gastric carcinogenesis.

Systems Biology of Gastric Cancer: Perspectives on the Omics-Based Diagnosis and Treatment

Gastric cancer is the fifth most diagnosed cancer in the world, affecting more than a million people and causing nearly 783,000 deaths each year. The prognosis of advanced gastric cancer remains extremely poor despite the use of surgery and adjuvant therapy. Therefore, understanding the mechanism of gastric cancer development, and the discovery of novel diagnostic biomarkers and therapeutics are major goals in gastric cancer research. Here, we review recent progress in application of omics technologies in gastric cancer research, with special focus on the utilization of systems biology approaches to integrate multi-omics data. In addition, the association between gastrointestinal microbiota and gastric cancer are discussed, which may offer insights in exploring the novel microbiota-targeted therapeutics. Finally, the application of data-driven systems biology and machine learning approaches could provide a predictive understanding of gastric cancer, and pave the way to the development of novel biomarkers and rational design of cancer therapeutics.

Relationship between time-varying status of reflux esophagitis and Helicobacter pylori and progression to long-segment Barrett's esophagus: time-dependent Cox proportional-hazards analysis

Background

Reflux esophagitis (RE) and absence of Helicobacter pylori (non-H. pylori) are considered to be associated with the progression to long-segment Barrett’s esophagus (LSBE). However, it is difficult to assess this association because RE and H. pylori status can change during follow-up. Additionally, the association between H. pylori eradication and LSBE remains unclear.

Methods

A total of 11,493 asymptomatic Japanese subjects who underwent medical check-ups and were endoscopically diagnosed with short-segment Barrett’s esophagus (SSBE) between May 2006 and December 2015 were enrolled. The hazards of progression to LSBE were compared between time-varying RE and H. pylori infection/eradication by time-dependent multivariable Cox proportional hazards models.

Results

A total of 7637 subjects who underwent additional medical check-ups after being diagnosed with endoscopic SSBE were analyzed. Subjects with RE and without current/past H. pylori infection were strongly associated with a higher rate of progression to LSBE (adjusted hazard ratio [HR]: 7.17, 95% confidence interval [CI]: 2.48–20.73, p < 0.001 for RE and non-H. pylori vs. non-RE and H. pylori groups). Subjects with H. pylori had a lower rate of progression to LSBE (adjusted HR: 0.48, 95% CI: 0.22–1.07, p = 0.07 for H. pylori vs. non-H. pylori). Hazards of progression to LSBE were still lower in the H. pylori eradication group than that of the non-H. pylori group (adjusted HR: 0.51, 95% CI: 0.18–1.46, p = 0.21).

Conclusions

RE and non-H. pylori were associated with the progression to LSBE, considering the changes in exposures. H. pylori infection was associated with the prevention of the development of LSBE irrespective of RE. The environment preventive of the development of LSBE persists for at least a few years after H. pylori eradication.

Changes in the human gut microbiota composition caused by Helicobacter pylori eradication therapy: A systematic review and meta-analysis

BACKGROUND

The short-term and long-term effect of Helicobacter pylori (H pylori) eradication on the gut microbiota is controversial; hence, this study aimed to clarify changes in the gut microbiome and microbial diversity after H pylori eradication.

MATERIALS AND METHODS

Articles published in PubMed, MEDLINE, and EMBASE were searched up to March 20, 2020, with English-language restriction. The outcomes including gut microbiota and alpha diversity were extracted to analysis. And then, Review Manager 5.3 software was used to conduct the data analysis.

RESULTS

At phylum level, next-generation sequencing was performed. Meta-analysis results showed that Actinobacteria decreased compared with baseline throughout the follow-up period. Proteobacteria increased during short-term follow-up and then returned to normal. In addition, Bacteroidetes decreased and Firmicutes increased only during long-term follow-up. At family or genus level, conventional microbiological culturing was performed. Enterobacteriaceae and Enterococcus both increased during the short-term and interim follow-up. In addition, Lactobacillus only showed a decreasing trend during short-term follow-up, but it appeared statistical decreasing during interim follow-up. Moreover, relatively sufficient evidence showed that alpha diversity decreased during short-term follow-up, and no reliable data were obtained to confirm the change of alpha diversity during interim and long-term follow-up.

CONCLUSION

In different follow-up periods after H pylori eradication, changes in gut microbiota were inconsistent. Microbial diversity decreased in the short-term follow-up, while there was no data to confirm subsequent alterations. The results provided a basis for the rational selection of probiotics in the eradication process. However, further studies are needed to obtain more clues.

Neonatal intestinal dysbiosis

The initial colonization of the neonatal intestinal tract is influenced by delivery mode, feeding, the maternal microbiota, and a host of environmental factors. After birth, the composition of the infant's microbiota undergoes a series of significant changes particularly in the first weeks and months of life ultimately developing into a more stable and diverse adult-like population in childhood. Intestinal dysbiosis is an alteration in the intestinal microbiota associated with disease and appears to be common in neonates. The consequences of intestinal dysbiosis are uncertain, but strong circumstantial evidence and limited confirmations of causality suggest that dysbiosis early in life can influence the health of the infant acutely, as well as contribute to disease susceptibility later in life.

Gastric cancer: Epidemiology, risk factors and prevention strategies

Gastric cancer (GC) is a global health problem, with more than 1 million people newly diagnosed with GC worldwide each year. GC is more prevalent in less developed countries than in more developed countries. About half of all GC cases worldwide occur in East Asia, notably China. Globally, overall incidence rates of GC are declining, which is potentially attributed to a decrease in Helicobacter pylori (H. pylori) infection and the use of refrigeration to preserve foods rather than salt. GC is a multifactorial disease, and its occurrence and development were impacted by environmental and genetic factors. H. pylori infection is the primary risk factor for GC, especially for non-cardia. The prognosis of GC is poor due to stages at the first diagnosis. The 5-year survival rate is less than 10% when patients are diagnosed at an advanced stage, but the rate is as high as 85% if patients are detected at an earlier stage. Endoscopic screening can potentially prevent GC by early diagnosis and early treatment and has been widely adopted in screening programs in East Asian countries, such as Japan and Korea. This review summarizes updated epidemiological aspects, risk factors, and prevention strategies of GC in recent years to help researchers determine the most effective intervention strategies for reducing risk of GC.