Helicobacter pylori promotes colorectal carcinogenesis by deregulating intestinal immunity and inducing a mucus-degrading microbiota signature

ABSTRACT OBJECTIVE H. pylori infection is the most prevalent bacterial infection worldwide. Besides being the most important risk factor for gastric cancer development, epidemiological data show that infected individuals harbor a nearly two-fold increased risk to develop colorectal cancer (CRC). However, a direct causal and functional connection between H. pylori infection and colon cancer is lacking. DESIGN We infected two Apc -mutant mouse models and C57BL/6 mice with H. pylori and conducted a comprehensive analysis of H. pylori -induced changes in intestinal immune responses and epithelial signatures via flow cytometry, chip cytometry, immunohistochemistry and single cell RNA sequencing. Microbial signatures were characterized and evaluated in germ-free mice and via stool transfer experiments. RESULTS H. pylori infection accelerated tumor development in Apc -mutant mice. We identified a unique H. pylori -driven immune alteration signature characterized by a reduction in regulatory T-cells and proinflammatory T-cells. Furthermore, in the intestinal and colonic epithelium, H. pylori induced pro-carcinogenic STAT3 signaling and a loss of goblet cells, changes that have been shown to contribute - in combination with pro-inflammatory and mucus degrading microbial signatures - to tumor development. Similar immune and epithelial alterations were found in human colon biopsies from H. pylori -infected patients. Housing of Apc -mutant mice under germ-free conditions ameliorated, and early antibiotic eradication of H. pylori infection normalized the tumor incidence to the level of uninfected controls. CONCLUSIONS Our studies provide evidence that H. pylori infection is a strong causal promoter of colorectal carcinogenesis. Therefore, implementation of H. pylori status into preventive measures of CRC should be considered.