Dataset Information

Metagenomic Evaluation of the Gut Microbiome in Patients With Lynch Syndrome and Other Hereditary Colonic Polyposis Syndromes

ABSTRACT: The purpose of this study is to understand the role bacteria that normally live in the colon may play in colorectal cancer risk, in addition to the hereditary risk to colorectal cancer. The investigators will collect stool specimens as well as additional colon biopsy specimens during the patient’s scheduled colonoscopy procedure. The investigators will also collect a questionnaire about diet and lifestyle. The samples will be used to study the impact of diet on naturally-occurring oral and gut bacteria and their influences on human health including risk of cancer.

DISEASE(S): Lynch Syndrome,Colorectal Neoplasms,Nasopharyngeal Neoplasms,Colorectal Neoplasms, Hereditary Nonpolyposis,Hereditary Colonic Polyposis Syndromes

PROVIDER: 2184420 | ecrin-mdr-crc |

REPOSITORIES: ECRIN MDR

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Project description:Colorectal cancer risk is associated with diets high in red meat. Heme, the pigment of red meat, induces cytotoxicity of colonic contents and elicits epithelial damage and compensatory hyperproliferation, leading to hyperplasia. Here we explore the possible causal role of the gut microbiota in heme-induced hyperproliferation. To this end, mice were fed a purified control or heme diet (0.5 μmol/g heme) with or without broad-spectrum antibiotics for 14 d. Heme-induced hyperproliferation was shown to depend on the presence of the gut microbiota, because hyperproliferation was completely eliminated by antibiotics, although heme-induced luminal cytotoxicity was sustained in these mice. Colon mucosa transcriptomics revealed that antibiotics block heme-induced differential expression of oncogenes, tumor suppressors, and cell turnover genes, implying that antibiotic treatment prevented the heme-dependent cytotoxic micelles to reach the epithelium. Our results indicate that this occurs because antibiotics reinforce the mucus barrier by eliminating sulfide-producing bacteria and mucin-degrading bacteria (e.g., Akkermansia). Sulfide potently reduces disulfide bonds and can drive mucin denaturation and microbial access to the mucus layer. This reduction results in formation of trisulfides that can be detected in vitro and in vivo. Therefore, trisulfides can serve as a novel marker of colonic mucolysis and thus as a proxy for mucus barrier reduction. In feces, antibiotics drastically decreased trisulfides but increased mucin polymers that can be lysed by sulfide. We conclude that the gut microbiota is required for heme-induced epithelial hyperproliferation and hyperplasia because of the capacity to reduce mucus barrier function. Mice were fed a Westernized high fat control diet, or the same diet supplemented with 0.5 µmol heme/g diet. One group of control and one group of heme mice received a mixture of broad spectrum Antibiotics (Abx) (ampicilin, neomycin and metronidazole) in their drinking water. After 14 days of intervention, mice were killed and gene expression was profiled in colon.

Dataset Information

Metagenomic Evaluation of the Gut Microbiome in Patients With Lynch Syndrome and Other Hereditary Colonic Polyposis Syndromes

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