TNF-α-induced down-regulation of CDX2 suppresses MEP1A expression in colitis.
OBJECTIVE
High levels of pro-inflammatory cytokines are linked to inflammatory bowel disease (IBD). The transcription factor Caudal-related homeobox transcription factor 2 (CDX2) plays a crucial role in differentiation of intestinal epithelium and regulates IBD-susceptibility genes, including meprin 1A (MEP1A). The aim was to investigate the expression of CDX2 and MEP1A in colitis; to assess if they are regulated by tumor necrosis factor-α (TNF-α), and finally to reveal if CDX2 is involved in a TNF-α-induced down-regulation of MEP1A.


METHODS
Expression of CDX2 and MEP1A was investigated in colonic biopsies of ulcerative colitis (UC) patients and in dextran sodium sulfate (DSS)-induced colitis. CDX2 protein expression was investigated by immunoblotting and immunohistochemical procedures. CDX2 and MEP1A regulation was examined in TNF-α-treated Caco-2 cells by reverse transcription-polymerase chain reaction and with reporter gene assays, and the effect of anti-TNF-α treatment was assessed using infliximab. Finally, in vivo CDX2-DNA interactions were investigated by chromatin immunoprecipitation.


RESULTS
The CDX2 and MEP1A mRNA expression was significantly decreased in active UC patients and in DSS-colitis. Colonic biopsy specimens from active UC showed markedly decreased CDX2 staining. TNF-α treatment diminished the CDX2 and MEP1A mRNA levels, a decrease which, was counteracted by infliximab treatment. Reporter gene assays showed significantly reduced CDX2 and MEP1A activity upon TNF-α stimulation. Finally, TNF-α impaired the ability of CDX2 to interact and activate its own, as well as the MEP1A expression.


CONCLUSIONS
The present results indicate that a TNF-α-mediated down-regulation of CDX2 can be related to suppressed expression of MEP1A during intestinal inflammation.
Department of Gastroenterology, Medical Section, Herlev Hospital, University of Copenhagen, Herlev, Denmark. mehmet.coskun@regionh.dk
Mehmet
M
Coskun
Anders Krüger
AK
Olsen
Thomas Lindebo
TL
Holm
Peter Helding
PH
Kvist
Ole Haagen
OH
Nielsen
Lene Buhl
LB
Riis
Jørgen
J
Olsen
Jesper Thorvald
JT
Troelsen
D000328:Adult; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000071616:CDX2 Transcription Factor; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D003093:Colitis, Ulcerative / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016264:Dextran Sulfate; D005260:Female; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000069285:Infliximab; D007413:Intestinal Mucosa / Q000378:metabolism; D008297:Male; D008666:Metalloendopeptidases / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D000071616:CDX2 Transcription Factor; C491270:CDX2 protein, human; D018398:Homeodomain Proteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D016264:Dextran Sulfate; D000069285:Infliximab; D008666:Metalloendopeptidases; C053833:meprin A