Activation of nuclear factor kappaB in colonic mucosa from patients with collagenous and ulcerative colitis.
OBJECTIVE
Expression of inducible nitric oxide synthase (iNOS) is greatly upregulated in the colonic mucosa of patients with collagenous and ulcerative colitis. As the transcription factor nuclear factor kappaB (NFkappaB) is a major inducer of iNOS gene expression, we compared activation and transcriptional activity of NFkappaB in colonic mucosal biopsies from these patients.


METHODS
Eight patients with collagenous colitis, six with relapsing ulcerative colitis, and eight with uninflamed bowel were studied.


METHODS
NFkappaB DNA binding activity was assessed by electrophoretic mobility shift assay and inhibitor of NFkappaB (IkappaB) kinase (IKK) activity by immunocomplex kinase assay. In vivo recruitment of NFkappaB to the iNOS promoter was determined by chromatin immunoprecipitation analysis and transcriptional activity by NFkappaB gene expression profiling arrays. Cells showing NFkappaB activation were identified by immunohistochemistry.


RESULTS
In collagenous and ulcerative colitis, as opposed to uninflamed bowel, IKKbeta activity and strong NFkappaB DNA binding gave rise to activation of identical NFkappaB subunits and recruitment of transcriptionally active p65 to the iNOS promoter. In collagenous colitis, activated NFkappaB was observed only in epithelial cells while up to 10% of lamina propria macrophages showed activation in ulcerative colitis.


CONCLUSIONS
In collagenous and ulcerative colitis, colonic mucosal NFkappaB is activated and recruited to the iNOS promoter in vivo via an IKKbeta mediated pathway. As collagenous colitis is not associated with tissue injury, these data challenge the prevailing view that activation of NFkappaB per se mediates tissue injury. Our results suggest that downstream inflammatory reactions leading to tissue damage originate in lamina propria immune cells, as increased NFkappaB activity in collagenous colitis was localised solely in epithelial cells, but present also in macrophages in ulcerative colitis.
Andresen
L
L
Department of Gastroenterology C-112, Herlev Hospital, Herlev Ringvej 75, DK-2730 Herlev, Denmark.
Jørgensen
V L
VL
Perner
A
A
Hansen
A
A
Eugen-Olsen
J
J
Rask-Madsen
J
J
D046729:Colitis, Collagenous / Q000378:metabolism*; D003093:Colitis, Ulcerative / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D020869:Gene Expression Profiling / Q000379:methods; D006801:Humans; D051550:I-kappa B Kinase; D007413:Intestinal Mucosa / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D014158:Transcription, Genetic; D014178:Translocation, Genetic
D004268:DNA-Binding Proteins; D016328:NF-kappa B; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human