Background The eradication of Helicobacter pylori (H pylori) has been suggested to reduce the risk of gastric cancer, but its impact on the gut microbiota has attracted public attention. This study aimed to investigate the short‐term and long‐term effects of bismuth quadruple therapy on both gastric and fecal microbiota. Methods Ten asymptomatic young adults with H pylori‐related gastritis were treated with bismuth quadruple therapy for 14 days, and 7 age‐matched adults without H pylori infection were enrolled as healthy controls. Both fecal and gastric mucosa samples were collected from H pylori‐positive patients at weeks 0, 6, and 26, while fecal samples were collected from healthy controls. The gastric and gut microbiota were analyzed by 16S rRNA gene sequencing. Results The structure of the gastric microbiota was significantly changed after the eradication of H pylori with increased alpha diversity over time. The relative abundance of H pylori sharply decreased from more than 70% to nearly 0% after treatment, while some beneficial bacteria, such as Lactobacillus and Bifidobacterium, were increased. The microbial diversity of gut microbiota was higher in H pylori‐infected patients than in healthy controls, which tended to decrease after eradication. The potentially beneficial gut bacteria Blautia and Lachnoclostridium were enriched at week 26 compared to week 0, while the pathogenic Alistipes were depleted to a level close to that of the healthy controls. Conclusions Bismuth quadruple therapy for H pylori eradication can restore the diversity of gastric microbiota with enrichment of beneficial bacteria. The composition of gut microbiota after H pylori eradication trends toward healthy status instead of becoming dysbiotic.

BackgroundHelicobacter pylori (H. pylori) delivers oncoprotein CagA into gastric epithelial cells via the T4SS and drives activation of multiple oncogenic signalling pathways. YAP, a core effector of the Hippo tumour suppressor pathway, is frequently overexpressed in human cancers, suggesting its potential tumor-promoting role. Although CagA is a casual factor in H. pylori induced gastric carcinogenesis, the link between CagA and YAP pathway has not been identified. In this work, we investigated the regulation of oncogenic YAP pathway by H. pylori CagA.MethodsExpression of YAP and E-cadherin protein in human gastric biopsies were assessed by immunohistochemistry. H. pylori PMSS1 cagA− isogenic mutant strains were generated. Gastric epithelial cells were co-cultured with H. pylori wild-type cagA+ strains or isogenic mutants and were also treated by recombinant CagA expression. Immunofluorescence was performed for YAP localization. Immunoblot and quantitative PCR were performed for examining levels of YAP, downstream effectors and markers of epithelial-mesenchymal transition. Verteporfin and siRNA silencing were used to inhibit YAP activity.ResultsYAP is significantly upregulated in human gastric carcinogenesis. We generated PMSS1 CagA isogenic mutant strains with chloramphenicol resistance successfully. Our analysis indicated that H. pylori infection induced YAP and downstream effectors in gastric epithelial cells. Importantly, knockout of CagA in 7.13 and PMSS1 strains reduced the expression of YAP by H. pylori infection. Moreover, Inhibition of YAP suppressed H. pylori infection-induced Epithelial-mesenchymal transition (EMT).ConclusionOur results indicated that H. pylori CagA as a pathogenic protein promotes oncogenic YAP pathway, which contributes to EMT and gastric tumorigenesis. This study provided a novel mechanistic insight into why cagA+ H. pylori infection is associated with a higher risk for the development of gastric cancer.Electronic supplementary materialThe online version of this article (10.1186/s13046-018-0962-5) contains supplementary material, which is available to authorized users.

Gastrointestinal (GI) cancers, especially gastric cancer and colorectal cancer (CRC), represent a major global health burden. A large population of microorganisms residing in the GI tract regulate physiological processes, such as the immune response, metabolic balance, and homeostasis. Accumulating evidence has revealed the alteration of microbial communities in GI tumorigenesis. Experimental studies in cell lines and animal models showed the functional roles and molecular mechanisms of several bacteria in GI cancers, including Helicobacter pylori in gastric cancer as well as Fusobacterium nucleatum, Escherichia coli, Peptostreptococcus anaerobius, and Bacteroides fragilis in CRC. The transcriptional factor NF-κB plays a crucial role in the host response to microbial infection through orchestrating innate and adaptive immune functions. Moreover, NF-κB activity is linked to GI cancer initiation and development through its induction of chronic inflammation, cellular transformation and proliferation. Here, we provide an overview and discussion of modulation of the NF-κB signaling pathway by microbiota, especially infectious bacteria, in GI tumorigenesis, with a major focus on gastric cancer and CRC.

Background Vonoprazan‐amoxicillin (VA) dual therapy has been shown to achieve acceptable cure rates for treatment of Helicobacter pylori(H. pylori) in Japan. Its effectiveness in other regions is unknown. We aimed to explore the efficacy of VA dual therapy as first‐line treatment for H. pyloriinfection in China. Methods This was a single center, prospective, randomized clinical pilot study conducted in China. Treatment naive H. pyloriinfected patients were randomized to receive either low‐ or high‐dose amoxicillin‐vonoprazan consisting of amoxicillin 1 g either b.i.d. or t.i.d plus VPZ 20 mg b.i.d for 7 or 10 days. 13C‐urea breath tests were used to access the cure rate at least 4 weeks after treatment. Results Three hundred and twenty‐three patients were assessed, and 119 subjects were randomized. The eradication rates of b.i.d. amoxicillin for 7 and 10 days, t.i.d. amoxicillin for 7 and 10 days were 66.7% (16/24), 89.2% (33/37), 81.0% (17/21), and 81.1% (30/37) (p = .191) by intention‐to‐treat analysis, respectively, and 72.7% (16/22), 89.2% (33/37), 81.0% (17/21), and 81.1% (30/37) (p = .454) by per‐protocol analysis, respectively. Conclusion Neither 7‐ or 10‐day VA dual therapy with b.i.d. or t.i.d. amoxicillin provides satisfied efficacy as the first‐line treatment for H. pyloriinfection in China. Further optimization is needed.