I'm sorry if this is a stupid question but I can't seem to find it.
I know its inhibition helps release cell-mediators, but where does it come from?
Try google. Quite a few scholarly references come up.
I will even post this which was fourth in the search list:
Two isoforms of the membrane protein COX are known: COX-1, which is constitutively expressed in most tissues, is responsible for the physiological production of prostaglandins; and COX-2, which is induced by cytokines, mitogens and endotoxins in inflammatory cells, is responsible for the elevated production of prostaglandins during inflammation.
. Explained here: Structural basis for selective inhibition of cyclooxygenase-2 by anti-inflammatory agents. - PubMed - NCBI