The Effects Of Polyunsaturated Fatty Acid Metabolites In Atherogensis And Atherosclerotic Progression

Aims:Atherosclerosis results from a maladaptive inflammatory response initiated by the intramural retention of low density lipoprotein cholesterol in susceptible areas of the arterial vasculature.Cells involved in the disease process mainly include the endothelial cells,the middle membrane smooth muscle cells and monocytes.However,the treatment of atherosclerosis is limited,mainly utilizing the statins to accelerate the clearance of LDL-C.If remain uncontrolled,fatty streaks will deteriorate into the vulnerable plaque,which may greatly increase the risk of myocardial infarction and induce cardiovascular events.The polyunsaturated fatty acids are rich in our dairy diet,mainly divided intoω-6andω-3 PUFA.As the main component ofω-6 PUFA,arachidonic acid can be metabolized by cyclooxygenase pathway,lipoxygenase pathway,or cytochrome P450pathway to produce small molecular active substances.Studies have shown that the EETs metabolized from P450 pathway,have anti-inflammatory and cardiovascular protective effects.However,the EETs can be hydrolyzed to non protective DHETs by soluble epoxide hydrolase.So inhibiting the activity of sEH may be a new target for the treatment of atherosclerosis.Similarlyω-3 PUFA has a wide range of cardiovascular protective effects,andω-3 PUFA can also produce small bioactive molecular through the three metabolic pathways ofω-6 PUFA.But the mechanism of these metabolites in the progression of atherosclerosis has not been elucidated,which may also be the target of atherosclerosis.Methods and results:In the first part,LDLR^-/-and LDLR^-/--sEH^-/-mice were selected as model,the control group was fed with the chow diet while the experimental group was fed with WTD.One of the LDLR^-/-mice group was fed with WTD along with sEH inhibitor tTUCB for 6 weeks.We found that gene knockout or drug inhibition of sEH activity significantly reduced the area of the lesion,the number of macrophage infiltration and the LDL-C level.The concentration of EET and DHET in plasma was analysed by UPLC-MS/MS.We found that the ratio of EET/DHET was increased after sEH activity decreased.To further investigate the effect of EETs on macrophages,we transplanted bone marrow cells from LDLR^-/-and LDLR^-/--sEH^-/-mice to LDLR^-/-mice.After 6 weeks of WTD feeding,we found the mice transplanted with LDLR^-/--sEH^-/-bone marrow cells,had less lesion area,and the proportion of Ly6C^hii monocytes in plaque was significantly reduced.Finally,we found that gene knockout or drug inhibition of sEH activity in monocytes increased the intracellular EET/DHET ratio,reduced the PSGL1 level at transcriptional levels,and reduced the adhesion of monocytes to P selectin or activated endothelial cells.In the second part,we determined the development of atherosclerosis in LDLR^-/-fed a WTD plusω-3 and LDLR^-/-and fat-1 transgenic(LDLR^-/--fat-1^tg)mice fed a WTD.The profiles ofω-3 PUFA in plasma were unbiased screened by UPLS-MS/MS.The content of 18-HEPE and 17,18-EEQ,from the cytochrome P450 pathway of EPA,was significantly higher in plasma from bothω-3 PUFA added and LDLR^-/--fat-1^tgg mice,compared with LDLR^-/-mice in WTD.We also studied the effect of metabolites of EPA on endothelial activation in vitro.18-HEPE and 17,18-EEQ were able to decrease inflammatory gene expression induced by TNFαvia NF-κB signaling,and inhibited monocyte adhesion to endothelial cells.Conclusion:Gene knockout or drug inhibition of sEH activity increased the EETs level in LDLR^-/-mice,reduced the adhesion to endothelial cells by reducing the PSGL1 gene expression in monocytes,and further alleviated the progression of atherosclerosis.Meanwhile,EPA protected against the development of atherosclerosis in atheroprone mice via the metabolites 18-HEPE and/or 17,18-EEQ,which reduced endothelial activation.These compounds may have therapeutic implications in atherosclerosis.