title: Characterization of the novel ST2/IL-33 system in patients with inflammatory bowel disease.
abstract: BACKGROUND
  ST2 has been proposed to be a regulator of inflammation and Th1/Th2 balance. ST2L is the IL-33 membrane receptor and belongs to the IL-1R family. The soluble variant, ST2s, is identical to the extracellular region of ST2L and competes for IL-33 binding, inhibiting receptor signaling. Although ST2s has been associated with inflammatory processes in patients with sepsis, trauma, asthma, and autoimmunity, until now there are no reported studies showing the role of ST2/IL-33 in inflammatory bowel disease (IBD).
  
  
  METHODS
  Expression of ST2 and IL-33 was determined in serum and colonic biopsies from IBD patients. ST2 transcript and protein was determined by reverse-transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA)/immunoblot, respectively, and IL-33 protein by ELISA. Intestinal mucosa localization of ST2 and IL-33 was conducted by immunofluorescence.
  
  
  RESULTS
  ST2s transcript in the colonic mucosa was mainly expressed in UC patients rather than Crohn's disease or control; however, ST2L mRNA remained constant in all samples. Total ST2 protein was significantly higher in mucosa samples from patients with active UC, with a predominant induction of ST2s that strongly correlates with serum ST2 levels. Mucosa IL-33 levels were higher in UC patients and serum levels were barely detected in all patient groups. ST2 and IL-33 are both abundantly expressed in the cytoplasm of epithelial cells of control subjects; however, in ulcerative colitis patients ST2 decreases and IL-33 showed cytoplasm-nuclear redistribution.
  
  
  CONCLUSIONS
  The novel association between the ST2/IL-33 system and IBD seems to identify that variations in this axis might regulate the inflammatory process in these diseases.
authors.affiliation: Disciplinary Program of Immunology, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago, Chile.
authors.forename: Caroll J
authors.initials: CJ
authors.lastname: Beltrán
authors.forename: Lucía E
authors.initials: LE
authors.lastname: Núñez
authors.forename: David
authors.initials: D
authors.lastname: Díaz-Jiménez
authors.forename: Nancy
authors.initials: N
authors.lastname: Farfan
authors.forename: Enzo
authors.initials: E
authors.lastname: Candia
authors.forename: Claudio
authors.initials: C
authors.lastname: Heine
authors.forename: Francisco
authors.initials: F
authors.lastname: López
authors.forename: María Julieta
authors.initials: MJ
authors.lastname: González
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Quera
authors.forename: Marcela A
authors.initials: MA
authors.lastname: Hermoso
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015153:Blotting, Western; D016022:Case-Control Studies; D003093:Colitis, Ulcerative / Q000235:genetics / Q000378:metabolism*; D003424:Crohn Disease / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D000072179:Interleukin-1 Receptor-Like 1 Protein; D000067596:Interleukin-33; D007378:Interleukins / Q000235:genetics / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055815:Young Adult
chemical_list: C079241:IL1RL1 protein, human; C506536:IL33 protein, human; D000072179:Interleukin-1 Receptor-Like 1 Protein; D000067596:Interleukin-33; D007378:Interleukins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface