11,12-Epoxyeicosatrienoic Acid Attenuates Adipose Inflammation in Diet-Induced Obese Mice

Epoxyeicosatrienoic acids (EETs), the epoxidation products of arachidonic acid, were shown to have vasodilation and anti-inflammatory activity in many tissues. In the present study, the roles and mechanisms of EETs in the development of inflammation in adipose tissue were investigated in obese mice. Diet-induced obesity models were established on male C57BL/6 mice, and randomly divided into three groups: OB group (saline), EET group (11,12-EET), or EEZE group (14,15-epoxyeicosa-5(Z)-enoicacid). The levels of cytochrome P450 (CYP) 2J6, hypoxia inducible factor (HIF)-1α, 11,12-EET, interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α were determined. Angiogenesis was evaluated with platelet endothelial cell adhesion molecule-1 (CD31); Insulin resistance was evaluated with homeostasis model assessment of insulin resistance (HOMA-IR). In diet-induced obese mice, CYP2J6 expression in both mRNA and protein levels was downregulated and 11,12-EET level was reduced, levels of IL-6, IL-1β, TNF-α, and HIF-1α were increased in epididymal adipose tissue and in serum compared with non-obese controls. These changes were attenuated by exogenous 11,12-EET, whereas but aggravated by 14,15-EEZE, an EET antagonist. CD31-positive cells in the epididymal adipose tissue of obese mice were markedly reduced, which was significantly improved by 11,12-EET. HOMA-IR was increased but markedly attenuated by 11,12-EET in obese mice. These findings indicate that dysregulation of the CYP epoxygenases/EETs pathway may contribute to adipose inflammation in diet-induced obese mice. Exogenous EETs may attenuate adipose inflammation through modulation of adipose angiogenesis and hypoxia, which may have a favorable effect on systemic insulin resistance.