Figure 1.

Overview of the study design

Bacterial DNA and human gastric mRNA samples were obtained from the biopsy and surgery cohorts. The biopsy cohort consisted of asymptomatic volunteers and patients with gastric cancer who were scheduled for upper gastrointestinal endoscopy. In this cohort, we compared the microbial composition and human gene expression patterns between disease groups (i.e., post-HP eradication, HP-associated gastritis, and gastric cancer) and the healthy stomach group. The surgery cohort consisted of patients with gastric cancer who underwent gastrectomy. In the surgery cohort, gastric cancer and adjacent severe gastritis tissues were obtained from each patient. Microbial composition and gene expression patterns were compared between the gastric cancer and adjacent severe gastritis groups. The association between the microbiome and transcriptome was analyzed using canonical correlation analysis. In addition, the immune cell composition of the tumor microenvironment was investigated through a gene signature-based inference algorithm. Immune cell compositions, and their links to the gastric microbiome, were compared between groups. HP, Helicobacter pylori.