title: M1 Macrophages Activate Notch Signalling in Epithelial Cells: Relevance in Crohn's Disease.
abstract: BACKGROUND
  The Notch signalling pathway plays an essential role in mucosal regeneration, which constitutes a key goal of Crohn's disease (CD) treatment. Macrophages coordinate tissue repair and several phenotypes have been reported which differ in the expression of surface proteins, cytokines and hypoxia-inducible factors (HIFs). We analysed the role of HIFs in the expression of Notch ligands in macrophages and the relevance of this pathway in mucosal regeneration.
  
  
  METHODS
  Human monocytes and U937-derived macrophages were polarized towards the M1 and M2 phenotypes and the expression levels of HIF-1α, HIF-2α, Jagged 1 (Jag1) and delta-like 4 (Dll4) were evaluated. The effects of macrophages on the expression of hairy and enhancer of split-1 (HES1, the main target of Notch signalling) and intestinal alkaline phosphatase (IAP, enterocyte marker) in epithelial cells in co-culture were also analysed. Phenotype macrophage markers and Notch signalling were evaluated in the mucosa of CD patients.
  
  
  RESULTS
  M1 macrophages were associated with HIF-1-dependent induction of Jag1 and Dll4, which increased HES1 protein levels and IAP activity in co-cultured epithelial cells. In the mucosa of CD patients a high percentage of M1 macrophages expressed both HIF-1α and Jag1 while M2 macrophages mainly expressed HIF-2α and we detected a good correlation between the ratio of M1/M2 macrophages and both HES1 and IAP protein levels.
  
  
  CONCLUSIONS
  M1, but not M2, macrophages are associated with HIF-1-dependent induction of Notch ligands and activation of epithelial Notch signalling pathway. In the mucosa of chronic CD patients, the prevalence of M2 macrophages is associated with diminution of Notch signalling and impaired enterocyte differentiation.
authors.affiliation: Departamento de Medicina, Facultad de Medicina, Universidad de Valencia, Valencia, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Ortiz-Masiá
authors.affiliation: Departamento de Farmacología and CIBER, Facultad de Medicina, Universidad de Valencia, Valencia, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Cosín-Roger
authors.affiliation: Departamento de Farmacología and CIBER, Facultad de Medicina, Universidad de Valencia, Valencia, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Calatayud
authors.affiliation: FISABIO, Hospital Dr Peset, Valencia, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Hernández
authors.affiliation: Hospital de Manises, Valencia, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Alós
authors.affiliation: Hospital de Manises, Valencia, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Hinojosa
authors.affiliation: Departamento de Farmacología and CIBER, Facultad de Medicina, Universidad de Valencia, Valencia, Spain FISABIO, Hospital Dr Peset, Valencia, Spain.
authors.forename: J V
authors.initials: JV
authors.lastname: Esplugues
authors.affiliation: Departamento de Farmacología and CIBER, Facultad de Medicina, Universidad de Valencia, Valencia, Spain dolores.barrachina@uv.es.
authors.forename: M D
authors.initials: MD
authors.lastname: Barrachina
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D018938:Caco-2 Cells; D016022:Case-Control Studies; D018920:Coculture Techniques; D003106:Colon / Q000378:metabolism* / Q000473:pathology; D003424:Crohn Disease / Q000378:metabolism* / Q000473:pathology; D016207:Cytokines / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D005260:Female; D019073:HT29 Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D051880:Receptors, Notch / Q000378:metabolism*; D015398:Signal Transduction; D055815:Young Adult
chemical_list: D015415:Biomarkers; D016207:Cytokines; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D051880:Receptors, Notch
keywords: Crohn’s disease; Macrophages; Notch signalling; mucosal healing