Microbiome and function alterations in the gastric mucosa of asymptomatic patients with Helicobacter pylori infection

Most patients with Helicobacter pylori (H. pylori) infection have no clinical symptoms, numerous studies reported the gastric microbiome in H. pylori-infected patients, but asymptomatic patients have not been distinguished. How the microbiome and function changes in asymptomatic patients with H. pylori infection remains poorly understood.

A total of 29 patients were divided into H. pylori-infected asymptomatic group (10 patients), H. pylori-infected symptomatic group (11 patients) and H. pylori-uninfected group (8 patients). Gastric mucosa specimens were taken for histopathological examination, special staining, and 16 S rDNA sequencing. High-throughput results were evaluated by community composition analysis, indicator species analysis, alpha diversity analysis, beta diversity analysis, and function prediction.

The gastric microbiota composition at phylum and genus level of H. pylori-infected asymptomatic patients were similar with H. pylori-infected symptomatic group, but different from H. pylori-uninfected patients. The diversity and richness of gastric microbial community declined significantly in H. pylori-infected asymptomatic group comparing with H. pylori-uninfected group. Sphingomonas may be an indicator between symptomatic and asymptomatic patients with H. pylori infection, the AUC value of Sphingomonas is 0.79. Interactions between species increased and altered notably after H. pylori infection. More genera were affected by Helicobacter in H. pylori-infected asymptomatic patients. The function condition changed significantly in asymptomatic patients with H. pylori infection, there was no difference comparing with symptomatic ones. Amino acid metabolism and lipid metabolism strengthened but carbohydrate metabolism remained constant after H. pylori infection. The metabolism of fatty acid and bile acid was disturbed after infection with H. pylori.

The gastric microbiota composition and function mode changed significantly after H. pylori infection regardless of the presence of clinical symptoms, there was no difference between H. pylori-infected asymptomatic and symptomatic patients. The difference in gastric microbiota composition and interactions between species might be responsible for presence of digestive symptoms.