Evaluation of gastric microbiome and metagenomic function in patients with intestinal metaplasia using 16S rRNA gene sequencing.
Park CH, Lee AR, Lee YR, Eun CS, Lee SK, Han DS
Helicobacter. Feb 2019. doi: 10.1111/hel.12547
COMMENT: In this study the authors try to find the influence of the gastric microbiome in the development of gastric cancers independently of Helicobacter pylori. To do so they analyze the gastric microbiome by means of 16S sequencing analysis in 6 groups of patients: H. pylori positive and negative patients with chronic superficial gastritis, instestinal metaplasia and cancer.
Despite recent advances in studies on the gastric microbiome, the role of the non-Helicobacter pylori gastric microbiome in gastric carcinogenesis remains unclear. We evaluated the characteristics of the gastric microbiome and metagenomic functions in patients with IM (Intestinal Metaplasia)
Among the 138 included patients, 48, 9, 23, 14, 12, and 32 were classified into the H. pylori‐negative CSG, H. pylori‐negative IM, H. pylori‐negative cancer, H. pylori‐positive CSG, H. pylori‐positive IM, and H. pylori‐positive cancer groups, respectively. Cyanobacteria were predominant in the H. pylori‐negative CSG group compared to in the H. pylori‐negative IM and H. pylori‐negative cancer groups (H. pylori‐negative CSG vs H. pylori‐negative IM vs H. pylori‐negative cancer: 14.0% vs 4.2% vs 0.04%, P < 0.001). In contrast, Rhizobiales were commonly observed in the H. pylori‐negative IM group (H. pylori‐negative CSG vs H. pylori‐negative IM vs H. pylori‐ negative cancer: 1.9% vs 15.4% vs 2.8%, P < 0.001). The relative abundance of Rhizobiales increased as H. pylori‐infected stomachs progressed from gastritis to IM. In the H. pylori‐negative IM group, genes encoding T4SS were prevalent among the metagenome. Additionally, after H. pylori‐ eradication therapy, the gastric microbiome was similar to the microbiome observed after spontaneous clearance of H. pylori
The relative abundance of Rhizobiales was higher in patients with H. pylori‐negative IM than in those with H. pylori‐negative CSG or cancer. Additionally, T4SS genes were highly observed in the metagenome of patients with IM. Highly abundant T4SS proteins in these patients may promote gastric carcinogenesis