title: Diet-induced hypoxia responsive element demethylation increases CEACAM6 expression, favouring Crohn's disease-associated Escherichia coli colonisation.
abstract: OBJECTIVE
  Adherent-invasive Escherichia coli (AIEC) are abnormally predominant on Crohn's disease (CD) ileal mucosa. AIEC strains adhere to enterocytes via interaction between type 1 pili and CEACAM6 receptors abnormally expressed on CD ileal mucosa, leading to gut inflammation. We analysed whether epigenetic mechanisms are involved in the upregulation of CEACAM6 expression in intestinal epithelial cells (IECs).
  
  
  METHODS
  Methylation of CEACAM6 promoter was analysed using bisulfite sequencing and site-specific methylation by SnapShot. pCpGfree reporter system was used to analyse CEACAM6 promoter activity. Transgenic mice expressing human CEACAM6 fed either standard food or a low-methyl diet (LMD) were orally challenged with 10(9) AIEC LF82. After 3 days, gut-associated AIEC and proinflammatory cytokines were quantified.
  
  
  RESULTS
  Analysis of CEACAM6 gene promoter revealed potentially methylated dinucleotide CpGs within HIF-1-responsive elements (HREs). Methylation levels of CpG within CEACAM6 promoter were inversely correlated with CEACAM6 expression in IEC expressing various levels of CEACAM6. We show the critical role of HRE methylation and transcription factor HIF-1 in the regulation of CEACAM6 gene in IEC. This was confirmed in transgenic mice expressing human CEACAM6 fed a LMD. LMD-dependent HRE demethylation led to abnormal gut expression of CEACAM6, favouring AIEC colonisation and subsequent inflammation.
  
  
  CONCLUSIONS
  HRE hypomethylation in CEACAM6 promoter correlates with high expression in IEC. Our findings suggest that abnormal DNA methylation leading to CEACAM6 increased expression and AIEC-mediated gut inflammation can be related to changes in nutritional habits, such as low intake in methyl donor molecules, leading to abnormal epigenetic marks in mouse model mimicking CD susceptibility.
authors.affiliation: Clermont Université, M2iSH, UMR 1071 INSERM/Université d'Auvergne, Clermont-Ferrand, France Unité Sous Contrat 2018 Institut National de la Recherche Agronomique, Clermont-Ferrand, France.
authors.forename: Jérémy
authors.initials: J
authors.lastname: Denizot
authors.affiliation: Departments of Oncogenetics and Breast Oncology, Centre Jean Perrin, Clermont-Ferrand, France.
authors.forename: Alexis
authors.initials: A
authors.lastname: Desrichard
authors.affiliation: Clermont Université, M2iSH, UMR 1071 INSERM/Université d'Auvergne, Clermont-Ferrand, France Unité Sous Contrat 2018 Institut National de la Recherche Agronomique, Clermont-Ferrand, France.
authors.forename: Allison
authors.initials: A
authors.lastname: Agus
authors.affiliation: Departments of Oncogenetics and Breast Oncology, Centre Jean Perrin, Clermont-Ferrand, France.
authors.forename: Nancy
authors.initials: N
authors.lastname: Uhrhammer
authors.affiliation: Clermont Université, M2iSH, UMR 1071 INSERM/Université d'Auvergne, Clermont-Ferrand, France Unité Sous Contrat 2018 Institut National de la Recherche Agronomique, Clermont-Ferrand, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Dreux
authors.affiliation: Institute for Research on Cancer and aging (IRCAN), Nice, France University of Nice-Sophia Antipolis, Nice, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Vouret-Craviari
authors.affiliation: Institute for Research on Cancer and aging (IRCAN), Nice, France University of Nice-Sophia Antipolis, Nice, France Laboratory of Clinical and Experimental Pathology and Human Biobank, Pasteur Hospital, Nice, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Hofman
authors.affiliation: Clermont Université, M2iSH, UMR 1071 INSERM/Université d'Auvergne, Clermont-Ferrand, France Unité Sous Contrat 2018 Institut National de la Recherche Agronomique, Clermont-Ferrand, France Institut Universitaire de Technologie, Génie Biologique, Aubière, France Centre Hospitalier Universitaire Clermont-Ferrand, France.
authors.forename: Arlette
authors.initials: A
authors.lastname: Darfeuille-Michaud
authors.affiliation: Clermont Université, M2iSH, UMR 1071 INSERM/Université d'Auvergne, Clermont-Ferrand, France Unité Sous Contrat 2018 Institut National de la Recherche Agronomique, Clermont-Ferrand, France Institut Universitaire de Technologie, Génie Biologique, Aubière, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Barnich
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism* / Q000502:physiology; D018938:Caco-2 Cells; D015815:Cell Adhesion Molecules / Q000378:metabolism* / Q000502:physiology; D003424:Crohn Disease / Q000209:etiology* / Q000378:metabolism / Q000382:microbiology; D019175:DNA Methylation; D004032:Diet / Q000009:adverse effects*; D044127:Epigenesis, Genetic; D004927:Escherichia coli Infections / Q000150:complications* / Q000378:metabolism; D058851:GPI-Linked Proteins / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism* / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic
chemical_list: D015703:Antigens, CD; C504117:CEACAM6 protein, human; D015815:Cell Adhesion Molecules; D058851:GPI-Linked Proteins; C575659:Gm5893 protein, mouse; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit
keywords: BACTERIAL INTERACTIONS; DIETARY FACTORS; FOLIC ACID; GENE REGULATION; IBD BASIC RESEARCH