Expression of cyclooxygenase-2 mRNA in active inflammatory bowel disease

In inflammatory bowel disease (IBD), increased amounts of prostaglandins correlate to disease activity. Prostaglandins are produced via the cyclooxygenase (COX) pathway and exhibit both pro- and anti-inflammatory effects. Whereas COX-1 is a constitutive enzyme present at all times and is thought to produce the cytoprotective prostaglandins, COX-2 represents the inducible form of cyclooxygenase leading to production of proinflammatory prostaglandins. In inflammatory bowel disease it is yet unclear whether COX-2 plays a role in the inflammatory response. The purpose of this study was to evaluate the role of COX-2 in inflammatory bowel disease.

Of the 44 individuals included in the study, 22 had ulcerative colitis, 11 had Crohn's disease, and 11 were healthy controls. Standard rigid rectoscopy was performed. The degree of inflammation was assessed using a semiquantitative scale. A biopsy was taken from the most affected area. mRNAs for COX-1 and COX-2 were detected using reverse transcription-polymerase chain reaction.

The fraction of patients demonstrating COX-2 mRNA significantly increased with increasing disease activity (p < 0.005), whereas the fraction of patients demonstrating COX-1 mRNA remained unchanged (p > 0.05).

This study demonstrates a clear relationship between endoscopic activity and relative presence of mRNA for COX-2. In contrast mRNA for COX-1 is detected equally often. This indicates that COX-2 is involved in the acute inflammatory response of chronic inflammatory bowel disease.