Gastrointestinal Microbiota Changes in Patients With Gastric Precancerous Lesions

Background: Gastric microbiota may be involved in gastric cancer (GC). The relationship between gastrointestinal microbes and the risk of GC is unclear. This study aimed to explore the gastric and intestinal bacteria associated with gastritis and precancerous lesions of gastric cancer (PLGC). Methods: We conducted a case-control study by performing 16S rRNA gene analysis of gastric biopsies, juices, and stool samples from 148 cases with gastritis or gastric precancerous lesions from Anhui and neighboring provinces, China. Findings: Analysis of microbial sequences revealed decreased bacterial alpha diversity metrics in gastric bacteria during the progression of gastritis. Helicobacter pylori was the main contributor to the decreased microbial composition and diversity in the gastric mucosa and had little influence on gastric juice and fecal microbiota. Aquabacterium was enriched, while Aquibacter, Veillonella, Escherichia, Stomatobaculum, and Rhizobium were depleted in the gastric mucosa of subjects with PLGC whether or not Helicobacter -positive cases were excluded. The changes in gastric juice and gastric mucosal bacteria during the progression of gastritis were not consistent. Aquabacterium was mainly associated with the intraepithelial neoplasia group. Bifidobacterium and Escherichia were enriched in the stomach with superficial gastritis, whereas Bifidobacterium was enriched in the intestinal metaplasia and intraepithelial neoplasia groups in the intestine. Interpretation: This study identified associations between gastric precancerous lesions and gastric microbiota, and corresponding changes in the intestinal microbiota. Funding: Science and Technology project of Anhui, China. Conflict of Interest: No potential conflicts of interest were declared. Ethical Approval: This study was approved by the Ethics Committee of the First Affiliated Hospital of University of science and technology of China (2019-ky064, Anhui, China), and informed consent was obtained from all participants before they enrolled in the study.