Targeting soluble epoxide hydrolase for inflammation and pain - an overview of pharmacology and the inhibitors.

Chronic inflammation is an important contributing factor to a variety of human diseases including rheumatoid arthritis, inflammatory bowel disease, psoriasis and atherosclerosis. Epoxidation of arachidonic acid by cytochrome P450 enzymes during inflammation yields epoxyeicosatrienoic acids (EETs). EETs have a variety of biological effects including modulation of inflammation, vascular smooth muscle migration and platelet aggregation. The EETs levels are regulated by soluble epoxide hydrolase (sEH), the major enzyme responsible for their degradation and conversion to inactive dihydroxyeicosatrienoic acids (DHETs); thereby limiting many of the biological actions of EETs. The molecular and pharmacological inhibition of sEH has been studied extensively for benefits on the cardiovascular system. More recent studies suggest the importance of EETs and sEH in pain and inflammation. This review will discuss the current status and emerging evidence on the role of sEH and sEH inhibitors in chronic inflammatory conditions such as atherosclerosis, colitis and arthritis. Although steroids and non-steroidal anti-inflammatory drugs are effective, their chronic use is limited by the metabolic and cardiovascular side effects. Currently there are no small molecule drugs for treatment of chronic inflammation and associated pain and sEH inhibitors with their intrinsic cardiovascular protective effects can potentially fill this void.