A COX-2 inhibitor (right) increases the expression of tissue factor (red) in heart vessels (arrows).
COX-2 is produced during infection and injury by the endothelial cells that line blood vessels. The enzyme converts a cellular lipid known as arachidonic acid into lipids that instigate fever, pain, and other uncomfortable hallmarks of inflammation.
COX-2 inhibitors such as Vioxx were popular antiinflammatory drugs until some users began to suffer serious side effects such as heart attack and stroke.
Ghosh et al. now find that the normally cardioprotective effect of COX-2 stems from its metabolic conversion not of arachidonic acid, but of other substrates: the endocannabinoids. Byproducts of these lipids, they found, activated a nuclear receptor and transcription factor,...
