Mucosal microbiome dysbiosis in gastric carcinogenesis.

Objectives We aimed to characterise the microbial changes associated with histological stages of gastric tumourigenesis. Design We performed 16S rRNA gene analysis of gastric mucosal samples from 81 cases including superficial gastritis (SG), atrophic gastritis (AG), intestinal metaplasia (IM) and gastric cancer (GC) from Xi’an, China, to determine mucosal microbiome dysbiosis across stages of GC. We validated the results in mucosal samples of 126 cases from Inner Mongolia, China. Results We observed significant mucosa microbial dysbiosis in IM and GC subjects, with significant enrichment of 21 and depletion of 10 bacterial taxa in GC compared with SG (q Peptostreptococcus stomatis , Streptococcus anginosus , Parvimonas micra , Slackia exigua and Dialister pneumosintes had significant centralities in the GC ecological network (p Helicobacter pylori -negative samples compared with H. pylori -positive samples in SG and IM. The fold changes of selected bacteria, and strengths of their interactions were successfully validated in the Inner Mongolian cohort, in which the five bacterial markers distinguished GC from SG with an AUC of 0.81. Conclusions In addition to microbial compositional changes, we identified differences in bacterial interactions across stages of gastric carcinogenesis. The significant enrichments and network centralities suggest potentially important roles of P. stomatis , D. pneumosintes , S. exigua , P. micra and S. anginosus in GC progression.