Gastric microbes associated with gastric inflammation, atrophy and intestinal metaplasia 1 year after Helicobacter pylori eradication

Salivary Microbiota for Gastric Cancer Prediction: An Exploratory Study

To characterize the salivary microbiota in patients at different progressive histological stages of gastric carcinogenesis and identify microbial markers for detecting gastric cancer, two hundred and ninety-three patients were grouped into superficial gastritis (SG; n = 101), atrophic gastritis (AG; n = 93), and gastric cancer (GC; n = 99) according to their histology. 16S rRNA gene sequencing was used to access the salivary microbiota profile. A random forest model was constructed to classify gastric histological types based on the salivary microbiota compositions. A distinct salivary microbiota was observed in patients with GC when comparing with SG and AG, which was featured by an enrichment of putative proinflammatory taxa including Corynebacterium and Streptococcus. Among the significantly decreased oral bacteria in GC patients including Haemophilus, Neisseria, Parvimonas, Peptostreptococcus, Porphyromonas, and Prevotella, Haemophilus, and Neisseria are known to reduce nitrite, which may consequently result in an accumulation of carcinogenic N-nitroso compounds. We found that GC can be distinguished accurately from patients with AG and SG (AUC = 0.91) by the random forest model based on the salivary microbiota profiles, and taxa belonging to unclassified Streptophyta and Streptococcus have potential as diagnostic biomarkers for GC. Remarkable changes in the salivary microbiota functions were also detected across three histological types, and the upregulation in the isoleucine and valine is in line with a higher level of these amino acids in the gastric tumor tissues that reported by other independent studies. Conclusively, bacteria in the oral cavity may contribute gastric cancer and become new diagnostic biomarkers for GC, but further evaluation against independent clinical cohorts is required. The potential mechanisms of salivary microbiota in participating the pathogenesis of GC may include an accumulation of proinflammatory bacteria and a decline in those reducing carcinogenic N-nitroso compounds.

The influence of the gastric microbiota in gastric cancer development

Colonization of the stomach by Helicobacter pylori is the trigger for a series of gastric mucosal changes that culminate in gastric cancer. Infection with this bacterium is considered the major risk factor for this malignancy. The introduction of high-throughput sequencing technologies coupled to advanced computational pipelines offered an improved understanding of the microbiome, and it is now currently accepted that, besides H. pylori, the stomach harbours a complex microbial community. While it is well established that H. pylori plays a central role in gastric carcinogenesis, the significance of the non-H. pylori microbiota is yet to be clarified. This review will address the state of the art on the relationship between the gastric microbiota and gastric cancer development, and identify areas where additional research is needed before translating microbiome research into preventive and therapeutic strategies to reduce gastric cancer burden.

Changes in Gastric Corpus Microbiota With Age and After Helicobacter pylori Eradication: A Long-Term Follow-Up Study

Helicobacter pylori infection changes gastric microbiota profiles. However, it is not clear whether H. pylori eradication can restore the healthy gastric microbiota. Moreover, there has been no study regarding the changes in gastric microbiota with aging. The objective of this study was to investigate the changes in gastric corpus microbiota with age and following H. pylori eradication. Changes in corpus mucosa-associated microbiota were evaluated in 43 individuals with endoscopic follow-up > 1 year, including 8 H. pylori-uninfected and 15 H. pylori-infected subjects with no atrophy/metaplasia by histology and pepsinogen I/II ratio > 4.0; 17 H. pylori-infected subjects with atrophy/metaplasia and pepsinogen I/II ratio < 2.5; and 3 subjects with atrophy/metaplasia, no evidence of active H. pylori infection, negative for anti-H. pylori immunoglobulin G (IgG) antibody testing, and no previous history of H. pylori eradication. Successful H. pylori eradication was achieved in 21 patients. The gastric microbiota was characterized using an Illumina MiSeq platform targeting 16S ribosomal DNA (rDNA). The mean follow-up duration was 57.4 months (range, 12-145 months), and median follow-up visit was 1 (range, 1-3). Relative abundance of Lactobacillales and Streptococcus was increased with atrophy/metaplasia. In H. pylori-uninfected subjects (n = 8), an increase in Proteobacteria (Enhydrobacter, Comamonadaceae, Sphingobium); a decrease in Firmicutes (Streptococcus, Veillonella), Fusobacteria (Fusobacterium), Nocardioidaceae, Rothia, and Prevotella; and a decrease in microbial diversity were observed during the follow-up (p trend < 0.05). In 10 of 21 subjects (47.6%), H. pylori eradication induced restoration of microbial diversity; however, a predominance of Acinetobacter with a decrease in microbial diversity occurred in 11 subjects (52.3%). The presence of atrophy/metaplasia at baseline and higher neutrophil infiltration in the corpus were associated with the restoration of gastric microbiota after successful eradication, whereas a higher relative abundance of Acinetobacter at baseline was associated with the predominance of Acinetobacter after H. pylori eradication (p < 0.05). To conclude, in H. pylori-uninfected stomach, relative abundance of Proteobacteria increases, relative abundance of Firmicutes and Fusobacteria decreases, and microbial diversity decreases with aging. H. pylori eradication does not always restore gastric microbiota; in some individuals, gastric colonization by Acinetobacter species occurs after anti-Helicobacter treatment.

Modulation of gastrointestinal bacterial in chronic atrophic gastritis model rats by Chinese and west medicine intervention

Chronic atrophic gastritis (CAG) is well-known related with multiple pathogenic factors and normally therapies comprised by western or Chinese medicines. The present study was designed to identify the bacterial community characterized by 16S rRNA amplicon sequencing and determine the modulate affection of bacterial composition response western and Chinese medicine Qinghuayin (QHY) as well as antibiotic on model rats. The result shown the overall structure alteration of bacterial appeared under medicine intervened, antibiotic caused a marked depletion in bacterial diversity and richness. The enrichments of Firmicutes (85.1-90.7%) in antibiotic-free converts into Bacteroidetes (30.7-34.6%) in antibiotic-added model rat were demonstrated. Firmicutes as the most dominant phylum in antibiotic-free treatments and significantly decreased till 21.9-68.5% in antibiotic-added treatments. Especially QHY-treated rats showed highest RA of Firmicutes (90.7%) and the amelioration of CAG using QHY attributed by beneficial bacterial enrichment, especially Ruminococcus, Lactobacillus and Bifidobacterium. In addition, alpha and beta diversity analysis also demonstrated the clear dispersion and aggregation that revealed the alteration and steady of bacterial community structures. In summary, QHY has potential application value in the treatment of CAG, which attributed to close relation with the modulatory of internal bacterial communities.

Microbiota alteration at different stages in gastric lesion progression: a population-based study in Linqu, China

In addition to Helicobacter pylori (H.pylori), gastric microbiota may be involved in carcinogenesis process. However, the longitudinal study to assess changes in the gastric microbiota associated with the development of gastric carcinogenesis is still limited. The aim of this study is to explore dynamic microbial alterations in gastric cancer (GC) development based on a 4-year endoscopic follow-up cohort in Linqu County, China. Microbial alterations were investigated by deep sequencing of the microbial 16S ribosomal RNA gene in 179 subjects with various gastric lesions, and validated in paired gastric biopsies prospectively collected before and after lesion progression and in non-progression controls. Significant differences were found in microbial diversity and community structure across various gastric lesions, with 62 candidate differential taxa between at least two lesion groups. Further validations identified Helicobacter, Bacillus, Capnocytophaga and Prevotella to be associated with lesion progression-to-dysplasia (DYS)/GC (all P < 0.05), especially for subjects progressing from intestinal metaplasia (IM) to DYS/GC. The combination of the four genera in a microbial dysbiosis index showed a significant difference after lesion progression-to-DYS/GC compared to controls (P = 0.027). The panel including the four genera identified subjects after progression-to-DYS/GC with an area under the receiver-operating curve (AUC) of 0.941. Predictive significance was found before lesion progression-to-DYS/GC with an AUC = 0.776 and an even better AUC (0.927) for subjects progressing from IM to DYS/GC. Microbiota may play different roles at different stages in gastric carcinogenesis. A panel of bacterial genera associated with gastric lesions may help to assess gastric microbial dysbiosis and show potential predictive values for lesion progression. Our findings provide new clues for the microbial mechanism of H.pylori-associated carcinogenesis.

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 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.

Management of Helicobacter pylori

PURPOSE OF REVIEW

Gastroenterologists and many general internists and primary care physicians confront questions regarding the management of Helicobacter pylori on a daily basis. The subject remains of global interest and continue to generate debate and research. Using the search terms 'pylori and treatment' or 'pylori and management' we identified over 1000 relevant articles in PubMed published over the time period 1 January 2019 to 30 April 2020. We have selected the most highly clinically relevant of these to review here.

RECENT FINDINGS

Clinical evidence grows regarding the benefits of H. pylori eradication on gastric cancer prevention. High rates of resistance to clarithromycin and levofloxacin, correlating with treatment failure in regimens utilizing these drugs, has stimulated interest in alternative regimens as well as the need for susceptibility testing of individual patients and populations. Although many aspects of H. pylori management are well established, implementation of appropriate testing and treatment pathways remains suboptimal throughout healthcare settings.

SUMMARY

Increased emphasis on measuring H. pylori-related clinical outcomes in practice is needed to identify implementation gaps, and to suggest means to best apply the knowledge gained on H. pylori for the prevention of gastric symptoms and disease.