Intestinal Microbiota Is Altered in Patients with Gastric Cancer from Shanxi Province, China

Research trends on the relationship between Microbiota and Gastric Cancer: A Bibliometric Analysis from 2000 to 2019

Background: Hundreds of studies have found that the microbiota contributes to the development of gastric cancer in the past two decades. This study aimed to access the research trends of microbiota and gastric cancer.

Materials and Methods: Publications from January 1, 2000 to December 31, 2019 were retrieved from the Web of Science Core Collection database and screened according to inclusion criteria. Different kinds of software, SPSS21.0, HistCite, VOSviewer, CiteSpace, and the online bibliometric analysis platform were used to evaluate and visualize the results.

Results: A total of 196 publications were finally identified, and the annual number of publications showed an increasing trend. These publications were from 44 countries and the USA showed its dominant position in publication outputs, H-index, total citations, and international collaborations. The journal of Helicobacter was the most productive journal. Correa P and Peek RM published the most papers, and the most productive institution was Vanderbilt University. The keyword of “Helicobacter pylori” ranked first in research frontiers and appeared earlier, and the keyword of “microbiota” began to appear in the past 3 to 5 years.

Conclusion: The annual number of publications would continue to grow. Besides the traditional Helicobacter pylori related researches, future research hotspots will focus on microbiota and its mechanism of action.

Nitrate ameliorates dextran sodium sulfate-induced colitis by regulating the homeostasis of the intestinal microbiota

Inflammatory bowel disease (IBD) involves chronic inflammation, loss of epithelial integrity, and gastrointestinal microbiota dysbiosis. Effective therapies for IBD have not been established. Accordingly, in this study, we evaluated the effects of inorganic nitrate, a potent nitric oxide (NO) donor and microbiota regulator, in a mouse model of dextran sodium sulfate (DSS)-induced colitis. Mice were pretreated with NaNO₃ (2 mM) in their drinking water for 5 days, and NaCl was used as a control. Feces were collected for microbiota analyses. The results showed that oral administration of dietary nitrate could maintained colon consistency, improved colon length, maintained body weight, decreased apoptosis in colon epithelial cells, and ameliorated inflammatory cell infiltration in both the colon and peripheral blood. Microbiota profiling revealed that nitrate regulated dysbiosis. Analysis of the top bacteria at the genus level showed that Bacteroidales_S24-7_group_unidentified, Lactobacillus, Bacteroides, and Prevotellaceae_UCG-001 decreased in the DSS group compared with that in the normal group, whereas Lactobacillus, Ruminococcaceae_UCG-014, and Prevotellaceae_UCG-001 were increased in the DSS + NaNO₃ group compared with that in the DSS group. The enriched bacteria in the nitrate group included Gordonibacter, Ureaplasama, and Lachnospiraceae_UCG-006. Moreover, microbiota analysis revealed that nitrate could partially decrease the enriched metabolic pathways (p53 signaling pathway and colorectal cancer pathway) compared with that in the DSS and DSS + NaCl groups. Overall, these findings indicated that nitrate could ameliorate DSS-induced colitis by decreasing inflammation, reducing apoptosis, and regulating the microbiota by activation of the NO₃^-/NO₂^-/NO pathway. Nitrate might be a potential treatment for colitis patients in the future clinical application.

Rewiring of Microbiota Networks in Erosive Inflammation of the Stomach and Small Bowel

The development of non-invasive, inexpensive, and effective early diagnosis tests for gastric and small-bowel lesions is an urgent requirement. The introduction of magnetically guided capsule endoscopy (MGCE) has aided examination of the small bowel for diagnoses. However, the distribution of the fecal microbiome in abnormal erosions of the stomach and small bowel remains unclear. Herein, alternations in the fecal microbiome in three groups [normal, small-bowel inflammation, and chronic gastritis (CG)] were analyzed by metagenomics and our well-developed method [individual-specific edge-network analysis (iENA)]. In addition to the dominant microbiota identified by the conventional differential analysis, iENA could recognize novel network biomarkers of microbiome communities, such as the genus Bacteroide in CG and small-bowel inflammation. Combined with differential network analysis, the network-hub microbiota within rewired microbiota networks revealed high-ranked iENA microbiota markers, which were disease specific and had particular pathogenic functions. Our findings illuminate the components of the fecal microbiome and the importance of specific bacteria in CG and small-bowel erosions, and could be employed to develop preventive and non-invasive therapeutic strategies.

Phytochemicals for the Prevention and Treatment of Gastric Cancer: Effects and Mechanisms

Gastric cancer is the fifth most common cancer, and the third most prevalent cause of cancer-related deaths in the world. Voluminous evidence has demonstrated that phytochemicals play a critical role in the prevention and management of gastric cancer. Most epidemiological investigations indicate that the increased intake of phytochemicals could reduce the risk of gastric cancer. Experimental studies have elucidated the mechanisms of action, including inhibiting cancer cell proliferation, inducing apoptosis and autophagy, and suppressing angiogenesis as well as cancer cell metastasis. These mechanisms have also been related to the inhibition of Helicobacter pylori and the modulation of gut microbiota. In addition, the intake of phytochemicals could enhance the efficacy of anticancer chemotherapeutics. Moreover, clinical studies have illustrated that phytochemicals have the potential for the prevention and the management of gastric cancer in humans. To provide an updated understanding of relationships between phytochemicals and gastric cancer, this review summarizes the effects of phytochemicals on gastric cancer, highlighting the underlying mechanisms. This review could be helpful for guiding the public in preventing gastric cancer through phytochemicals, as well as in developing functional food and drugs for the prevention and treatment of gastric cancer.

Review: Gastric malignancies: Basic aspects

Gastric cancer is the third deadliest cancer in the world, and the absolute number of cases is increasing every year due to aging and growing of high-risk populations. This disease is a consequence of the complex interaction of microbial agents, with environmental and host factors, resulting in the dysregulation of multiple oncogenic and tumor-suppressing signaling pathways. Despite the advances in our understanding of carcinogenesis, there are still reduced therapeutic options for patients with gastric cancer. In recent years, genomic analyses of gastric tumors have emphasized their molecular heterogeneity. The distinction of gastric cancer molecular subtypes may be a key to identify novel therapeutic targets, to predict patient outcome and response to therapy, and to guide early diagnosis strategies. In this review, we summarize the most recent updates on the relationship between microbial agents and gastric cancer, in particular, Helicobacter pylori, the non-H pylori microbiome, and Epstein-Barr virus. We also highlight the main advances made in the past year regarding the molecular characterization of gastric cancer, especially the signatures with potential clinical utility.