Cyclooxygenase 2 is induced in colonic epithelial cells in inflammatory bowel disease.
OBJECTIVE
Prostaglandins are synthesized by cyclooxygenases (COX)-1 and -2. The expression and cellular localization of COX-1 and COX-2 in normal human colon and inflammatory bowel disease (IBD) surgical resections were studied.


METHODS
COX-1 and COX-2 protein expression and cellular localization were assessed by Western blotting and immunohistochemistry.


RESULTS
COX-1 protein was expressed at equal levels in normal, Crohn's disease, and ulcerative colitis colonic epithelial cells. COX-2 protein was not detected in normal epithelial cells but was detected in Crohn's disease and ulcerative colitis epithelial cells. Immunohistochemistry of normal, Crohn's colitis, and ulcerative colitis tissue showed equivalent COX-1 expression in epithelial cells in the lower half of the colonic crypts. COX-2 expression was absent from normal colon, whereas in Crohn's colitis and ulcerative colitis, COX-2 was observed in apical epithelial cells and in lamina propria mononuclear cells. In Crohn's ileitis, COX-2 was present in the villus epithelial cells. In ulcerative colitis, colonic epithelial cells expressing COX-2 also expressed inducible nitric oxide synthase.


CONCLUSIONS
COX-1 was localized in the crypt epithelium of the normal ileum and colon, and its expression was unchanged in IBD. COX-2 was undetectable in normal ileum or colon, but it was induced in apical epithelial cells of inflamed foci in IBD.
Singer
I I
II
Department of Inflammation Research, Merck Research Laboratories, Rahway, New Jersey, USA.
Kawka
D W
DW
Schloemann
S
S
Tessner
T
T
Riehl
T
T
Stenson
W F
WF
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003092:Colitis / Q000201:enzymology; D003093:Colitis, Ulcerative / Q000201:enzymology; D003106:Colon / Q000201:enzymology*; D003424:Crohn Disease / Q000201:enzymology; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D004790:Enzyme Induction / Q000502:physiology; D005260:Female; D006801:Humans; D007079:Ileitis / Q000201:enzymology; D015212:Inflammatory Bowel Diseases / Q000201:enzymology* / Q000601:surgery; D007413:Intestinal Mucosa / Q000201:enzymology*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012016:Reference Values
D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases