title: Gut microbiota facilitates dietary heme-induced epithelial hyperproliferation by opening the mucus barrier in colon.
abstract: 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.
authors.affiliation: Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands; Nutrition, Metabolism & Genomics Group, Division of Human Nutrition, Wageningen University, 6703 HD, Wageningen, The Netherlands; Department of Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, 3508 AB, Utrecht, The Netherlands; n.ijssennagger@umcutrecht.nl.
authors.forename: Noortje
authors.initials: N
authors.lastname: Ijssennagger
authors.affiliation: Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands; Laboratory of Microbiology, Wageningen University, 6703 HB, Wageningen, The Netherlands;
authors.forename: Clara
authors.initials: C
authors.lastname: Belzer
authors.affiliation: Nutrition, Metabolism & Genomics Group, Division of Human Nutrition, Wageningen University, 6703 HD, Wageningen, The Netherlands;
authors.forename: Guido J
authors.identifier: http://orcid.org/0000-0003-1954-3542
authors.initials: GJ
authors.lastname: Hooiveld
authors.affiliation: Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands; Host Microbe Interactomics Group, Animal Science Department, 6700 AH, Wageningen, The Netherlands;
authors.forename: Jan
authors.initials: J
authors.lastname: Dekker
authors.affiliation: Department of Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, 3508 AB, Utrecht, The Netherlands;
authors.forename: Saskia W C
authors.initials: SW
authors.lastname: van Mil
authors.affiliation: Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands; Nutrition, Metabolism & Genomics Group, Division of Human Nutrition, Wageningen University, 6703 HD, Wageningen, The Netherlands;
authors.forename: Michael
authors.initials: M
authors.lastname: Müller
authors.affiliation: Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands; Host Microbe Interactomics Group, Animal Science Department, 6700 AH, Wageningen, The Netherlands; Health Department, NIZO Food Research, 6710 BA, Ede, The Netherlands.
authors.forename: Michiel
authors.initials: M
authors.lastname: Kleerebezem
authors.affiliation: Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands; Nutrition, Metabolism & Genomics Group, Division of Human Nutrition, Wageningen University, 6703 HD, Wageningen, The Netherlands;
authors.forename: Roelof
authors.initials: R
authors.lastname: van der Meer
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D015415:Biomarkers / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D016923:Cell Death / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003106:Colon / Q000187:drug effects / Q000382:microbiology* / Q000473:pathology*; D015169:Colony Count, Microbial; D004032:Diet; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D005243:Feces / Q000382:microbiology; D006418:Heme / Q000494:pharmacology*; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000187:drug effects / Q000382:microbiology / Q000473:pathology; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D008810:Mice, Inbred C57BL; D064307:Microbiota / Q000187:drug effects*; D008954:Models, Biological; D009093:Mucus / Q000187:drug effects / Q000378:metabolism*; D013440:Sulfides / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D000975:Antioxidants; D015415:Biomarkers; D019394:Ki-67 Antigen; D013440:Sulfides; D006418:Heme
keywords: (tri)sulfides; colorectal cancer; mucolysis; mucus barrier; red meat