The Effects Of Cytochrome P450 Epoxygenase-EETs Pathway In Adipose Tissue Inflammation And The Development Of Obesity-induced Insulin Resistance

Diabetes mellitus(DM)is one of the most important non-communicable diseases that threaten global human health.The prevalence of diabetes in China has increased significantly,and the incidence is younger.Insulin resistance(IR)and islet dysfunction are the pathological basis of metabolic diseases such as type 2 diabetes.However,the exact etiology and pathogenesis of IR has not been fully elucidated.In recent years,epoxyeicosatrienoic acids(EETs)is a metabolite of arachidonic acid(AA)cytochrome P450 oxidase(CYP450)pathway,with a wide range of biological effects,especially for pathology such as inflammation and angiogenesis.Physiological processes have important regulatory roles.Some searches have found that the expression level of CYP in obese patients with insulin resistance is lower than normal.As a consequence,is obesity-induced diabetes insulin resistance associated with abnormalities in the CYP450-EETs metabolic pathway?Aim:To investigate the effects of Cytochrome P450 epoxygenase pathway on diabetic insulin resistance,and to explore the possible mechanisms underlyingMethods:Obesity models were constructed on C57BL/6 mice,then,obese mice were randomly divided into 3 groups,including saline,11,12-EET and EET inhibitor for treatment,normal C57BL/6 mice were treated with saline as control.mRNA and protein expression of epoxygenase were detected by RT-PCR and western blotting,respectively;expression of HIF-1a were measured by western blotting;Vascular-like structures was detected by immunofluorescence;the levels of tumor necrosis factor(TNF-α),interleukin(IL)-1β,IL-6 and MCP-1 were measured by enzyme-linked immuno-sorbent assay(ELISA).Results:1.Compared to control mice,HOMA-IR levels were significantly increased in obese mice(P<0.05,respectively).11,12-EET significantly accelerated IR as compared with vehicle-treated obese mice.(P<0.05,respectively).2.Compared to control mice,CYP2J2 expression levels in adipose tissue were significantly decreased in obese mice compared with control mice(P<0.05,respectively).3.Compared to control mice,HIF-1a expression levels in adipose tissue were significantly increased in obese mice(P<0.05,respectively).11,12-EET significantly improved anoxic conditions in adipose tissue as compared with vehicle-treated in obese mice.4.At day 7 after drugs treatment,the levels of IL-1β,IL-6 and TNF-α in the serum of obese mice were far higher than normal C57BL/6 mice.11,12-EET treatment significantly reduced the levels of these pro-inflammatory compared to vehicle-treated obese mice(P<0.05).5.At day 7 after drugs treatment,immunohistochemistry of adipose tissue from vehicle-treated obese mice showed a striking decrease in vascular-like structures(CD31-positive)compared with normal C57BL/6 control mice(P<0.05).EET treatment significantly increased the newly formed vascular-like structures in obese mice when copmpared with vehicle-treated obese mice(P<0.05).6.Compared to control mice,p-AKT/AKT expression levels in muscle tissue were significantly decreased in obese mice(P<0.05,respectively).11,12-EET significantly improved p-AKT/AKT expression levels in obese mice muscle tissue as compared with vehicle-treated in obese mice.Conclusions:1.Treatment with EETs can improve insulin resistance in obese mice.2.The protein expression levels of CYP2J2 in adipose tissue in obese mice were significantly reduced compared to normal C57BL/6 mice.3.Treatment with EETs can improve the anoxic conditions in adipose tissue of obese mice.4.Administration of exogenous EETs resulted in reduced production of inflammatory cytokines in obese mice serum.5.EETs increased angiogenesis in the adipose tissue in obese mice.6.EETs increased the phosphorylation level of p-AKT in muscle tissue of obese mice.Taken together,these findings indicated that low expression of CYP is an important cause of obesity-induced insulin resistance.Supplementation of exogenous EET can effectively improve the degree of insulin resistance induced by obesity.Its mechanism of action may be related to the anti-inflammatory and prophylactic effects of EET.Significance:In this study,we demonstrated CYP450-EETs metabolic pathway is one of the important factors affecting insulin resistance induced by obesity;further reveals the pathophysiological mechanism of obesity-induced insulin resistance.Increasing the expression of the CYP450-EETs pathway,or exogenous application of EET,may serve as a potential therapeutic target for obesity-induced insulin resistance.