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ObjectiveHelicobacter pyloriinfection is the most prevalent bacterial infection worldwide. Besides being the most important risk factor for gastric cancer development, epidemiological data show that infected individuals harbour a nearly twofold increased risk to develop colorectal cancer (CRC). However, a direct causal and functional connection betweenH. pyloriinfection and colon cancer is lacking.DesignWe infected twoApc-mutant mouse models and C57BL/6 mice withH. pyloriand conducted a comprehensive analysis ofH. pylori-induced changes in intestinal immune responses and epithelial signatures via flow cytometry, chip cytometry, immunohistochemistry and single cell RNA sequencing. Microbial signatures were characterised and evaluated in germ-free mice and via stool transfer experiments.ResultsH. pyloriinfection accelerated tumour development inApc-mutant mice. We identified a uniqueH. pylori-driven immune alteration signature characterised by a reduction in regulatory T cells and pro-inflammatory T cells. Furthermore, in the intestinal and colonic epithelium,H. pyloriinduced pro-carcinogenic STAT3 signalling and a loss of goblet cells, changes that have been shown to contribute—in combination with pro-inflammatory and mucus degrading microbial signatures—to tumour development. Similar immune and epithelial alterations were found in human colon biopsies fromH. pylori-infected patients. Housing ofApc-mutant mice under germ-free conditions ameliorated, and early antibiotic eradication ofH. pyloriinfection normalised the tumour incidence to the level of uninfected controls.ConclusionsOur studies provide evidence thatH. pyloriinfection is a strong causal promoter of colorectal carcinogenesis. Therefore, implementation ofH. pyloristatus into preventive measures of CRC should be considered.

The gastric pathogen Helicobacter pylori infects half of the world’s population and is a major risk factor for gastric cancer development. In order to attach to human gastric epithelial cells and inject the oncoprotein CagA into host cells, H. pylori utilizes the outer membrane protein HopQ that binds to the cell surface protein CEACAM, which can be expressed on the gastric mucosa. Once bound, H. pylori activates a number of signaling pathways, including canonical and non-canonical NF-κB. We investigated whether HopQ–CEACAM interaction is involved in activating the non-canonical NF-κB signaling pathway. Different gastric cancer cells were infected with the H. pylori wild type, or HopQ mutant strains, and the activation of non-canonical NF-κB was related to CEACAM expression levels. The correlation between CEACAM levels and the activation of non-canonical NF-κB was confirmed in human gastric tissue samples. Taken together, our findings show that the HopQ–CEACAM interaction is important for activation of the non-canonical NF-κB pathway in gastric epithelial cells.

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.