Expression Of Soluble Epoxide Hydrolase Research Articles

Decreased Expression of Soluble Epoxide Hydrolase Suppresses Murine Choroidal Neovascularization.

Neovascular or "wet" age-related macular degeneration (nAMD) is a leading cause of blindness among older adults. Choroidal neovascularization (CNV) is a major pathological feature of nAMD, in which abnormal new blood vessel growth from the choroid leads to irreversible vision loss. There is a critical need to develop novel therapeutic strategies to address limitations of the current anti-vascular endothelial growth factor biologics. Previously, we identified soluble epoxide hydrolase (sEH) as a possible therapeutic target for CNV through a forward chemical genetic approach. The purpose of this study was to validate sEH as a target by examining retinal expression of sEH protein and mRNA by immunohistochemistry and RNAscope in situ hybridization, respectively, and to assess the efficacy of an adeno-associated virus (AAV) vector designed to knock down the sEH gene, Ephx2, in the murine laser-induced (L-) CNV model. nAMD patient postmortem eye tissue and murine L-CNV showed overexpression of sEH in photoreceptors and retinal pigment epithelial cells. Ephx2 knockdown significantly reduced CNV and normalized mRNA expression levels of CNV-related inflammatory markers. Thus, this study further establishes sEH as a promising therapeutic target against CNV associated with nAMD.

Deletion of soluble epoxide hydrolase suppressed chronic kidney disease-related vascular calcification by restoring Sirtuin 3 expression

Vascular calcification is common in chronic kidney disease (CKD) and contributes to cardiovascular disease (CVD) without any effective therapies available up to date. The expression of soluble epoxide hydrolase (sEH) is different in patients with and without vascular calcification. The present study investigates the role of sEH as a potential mediator of vascular calcification in CKD. Both Ephx2−/− and wild-type (WT) mice fed with high adenine and phosphate (AP) diet were used to explore the vascular calcification in CKD. Compared with WT, deletion of sEH inhibited vascular calcification induced by AP. sEH deletion also abolished high phosphorus (Pi)-induced phenotypic transition of vascular smooth muscle cells (VSMCs) independent of its epoxyeicosatrienoic acids (EETs) hydrolysis. Further gene expression analysis identified the potential role of Sirtuin 3 (Sirt3) in the sEH-regulated VSMC calcification. Under high Pi treatment, sEH interacted with Sirt3, which might destabilize Sirt3 and accelerate the degradation of Sirt3. Deletion of sEH may preserve the expression of Sirt3, and thus maintain the mitochondrial adenosine triphosphate (ATP) synthesis and morphology, significantly suppressing VSMC calcification. Our data supported that sEH deletion inhibited vascular calcification and indicated a promising target of sEH inhibition in vascular calcification prevention.

Evaluating the protective effects of individual or combined ginsenoside compound K and the downregulation of soluble epoxide hydrolase expression against sodium valproate-induced liver cell damage

Sodium valproate (SVP) is one of the most commonly prescribed antiepileptic drugs. However, SVP is known to induce hepatotoxicity, which limits its clinical application for treating various neurological disorders. Previously, we found that ginsenoside compound K (G-CK) demonstrated protective effects against SVP-induced hepatotoxicity by mitigating oxidative stress and mitochondrial damage, as well as downregulating the expression of soluble epoxide hydrolase (sEH) in rats. This study aimed to assess the effect of G-CK on SVP-induced cytotoxicity in human hepatocytes (L02 cell line), as well as the effect of the downregulation of sEH expression on both the hepatotoxicity of SVP and the hepatoprotective effects of G-CK. We observed that G-CK significantly ameliorated the decrease of cell viability, elevated ALT, AST and ALP activities, significant oxidative stress, and loss of mitochondrial membrane potential induced by SVP in L02 cells. G-CK also inhibited the SVP-mediated upregulation of sEH expression. Transfection of the L02 cells with siRNA-sEH led to a partial improvement in the L02 cytotoxicity caused by SVP by mitigating cellular oxidative stress without recovering the reduced mitochondrial membrane potential. Furthermore, the combination of siRNA-sEH and G-CK had better inhibitory effects on the SVP-induced changes of all detection indices except mitochondrial membrane potential than G-CK alone. Together, our results demonstrated that the combination of siRNA-sEH and G-CK better suppressed the SVP-induced cytotoxicity in L02 cells compared to either G-CK or siRNA-sEH alone.

Maternal glyphosate exposure causes autism-like behaviors in offspring through increased expression of soluble epoxide hydrolase

Epidemiological studies suggest that exposure to herbicides during pregnancy might increase risk for autism spectrum disorder (ASD) in offspring. However, the precise mechanisms underlying the risk of ASD by herbicides such as glyphosate remain unclear. Soluble epoxide hydrolase (sEH) in the metabolism of polyunsaturated fatty acids is shown to play a key role in the development of ASD in offspring after maternal immune activation. Here, we found ASD-like behavioral abnormalities in juvenile offspring after maternal exposure to high levels of formulated glyphosate. Furthermore, we found higher levels of sEH in the prefrontal cortex (PFC), hippocampus, and striatum of juvenile offspring, and oxylipin analysis showed decreased levels of epoxy-fatty acids such as 8 (9)-EpETrE in the blood, PFC, hippocampus, and striatum of juvenile offspring after maternal glyphosate exposure, supporting increased activity of sEH in the offspring. Moreover, we found abnormal composition of gut microbiota and short-chain fatty acids in fecal samples of juvenile offspring after maternal glyphosate exposure. Interestingly, oral administration of TPPU (an sEH inhibitor) to pregnant mothers from E5 to P21 prevented ASD-like behaviors such as social interaction deficits and increased grooming time in the juvenile offspring after maternal glyphosate exposure. These findings suggest that maternal exposure to high levels of glyphosate causes ASD-like behavioral abnormalities and abnormal composition of gut microbiota in juvenile offspring, and that increased activity of sEH might play a role in ASD-like behaviors in offspring after maternal glyphosate exposure. Therefore, sEH may represent a target for ASD in offspring after maternal stress from occupational exposure to contaminants.

Increased expression of soluble epoxide hydrolase in the brain and liver from patients with major psychiatric disorders: A role of brain – liver axis

BackgroundSoluble epoxide hydrolase (sEH) in the metabolism of polyunsaturated fatty acids might play a role in the pathogenesis of major psychiatric disorders. Here we studied whether expression of sEH protein is altered in the postmortem samples (parietal cortex, and liver) from patients with major psychiatric disorders. MethodsProtein expression of sEH in the parietal cortex and liver from control, major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia (SZ) groups was measured. ResultsLevels of sEH in the parietal cortex and liver from MDD, BD, and SZ groups were significantly higher than the control group. Interestingly, there was a positive correlation between sEH protein in the parietal cortex and sEH protein the liver in all groups. LimitationsThe small number in each group may limit our interpretation. ConclusionsThis study shows that the increased expression of sEH in the brain and liver might play a role in the pathogenesis of major psychiatric disorders, suggesting a role of brain – liver axis in major psychiatric disorders.

Maternal Glyphosate Exposure Causes Autism‐like Behaviors in Offspring through Increased Expression of Soluble Epoxide Hydrolase

The number of children with autism spectrum disorder (ASD) has increased dramatically since the 1980s. Epidemiological studies suggest that exposure to pesticides (i.e., glyphosate) during pregnancy might increase the risk for ASD in offspring. Recently, we demonstrated that soluble epoxide hydrolase (sEH) in the metabolism of polyunsaturated fatty acids plays a key role in the development of ASD in offspring after maternal immune activation. In the present study, we found ASD‐like behavioral abnormalities in juvenile offspring after maternal glyphosate exposure. Furthermore, we found higher levels of sEH in the prefrontal cortex (PFC), hippocampus, and striatum of juvenile offspring after maternal glyphosate exposure. Oxylipin analysis showed decreased levels of epoxy‐fatty acids (i.e., 8(9)‐EpETrE [8,9‐epoxy‐5Z,11Z,14Z‐eicosatrienoic acid] in the blood, PFC, hippocampus, and striatum of juvenile offspring after maternal glyphosate exposure, supporting increased activity of sEH in juvenile offspring. The 16S rRNA analysis demonstrated abnormal composition of gut microbiota in fecal samples of juvenile offspring after maternal glyphosate exposure. Interestingly, oral administration of TPPU to pregnant mothers from E5 to P21 could prevent social interaction deficits, increased grooming time in the juvenile offspring after maternal glyphosate exposure. These findings suggest that maternal glyphosate exposure causes ASD‐like behavioral abnormalities and abnormal composition of gut microbiota in juvenile offspring, and that increased activity of sEH plays a key role in ASD‐like behaviors in offspring after maternal glyphosate exposure. Therefore, sEH would represent a promising prophylactic target for ASD in offspring after maternal glyphosate exposure.Support or Funding InformationThis study was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (to K.H., 17H04243), AMED (to K.H., JP19dm0107119), the National Institute of Environmental Health Sciences (NIEHS) R01 ES002710 (to B.D.H.), NIEHS Superfund Program P42 ES004699 (to B.D.H.).

Effects of diabetes-related stimuli on soluble epoxide hydrolase expression

Background and Hypothesis: Diabetic retinopathy (DR) is a frequent complication of diabetes and is a leading cause of blindness in the developed world. While the treatment of DR has progressed with the use of anti-VEGF therapies, the underlying mechanisms for DR are still unknown. Soluble epoxide hydrolase (sEH) activity has been linked to retinal neovascularization, which can lead to blindness in proliferative DR. The use of sEH inhibitors also slowed the progression of experimental DR. In particular, sEH might be expressed in the retinal pigment epithelium (RPE), which is a critical player in metabolic processing and could be influenced by diabetes-related stimuli to promote neovascularization. We hypothesize that stimuli seen in diabetes can lead to sEH overexpression in human retinal pigmented epithelial cells (ARPE-19).
 Experimental Design or Project Methods: To test our hypothesis, we examined sEH expression in ARPE-19 cells treated under hyperglycemic and hypoxic conditions similar to those of a diabetic retina. ARPE19 were treated with increasing doses of these stimuli and underwent RNA isolation, RT-PCR to study mRNA expression of sEH, and immunoblotting to study protein expression of sEH.
 Results: After hyperglycemia treatment, there was a 1.5-fold increase in protein level of sEH from the control at 10 mM glucose and a 1.2-fold increase at 20 mM glucose. However, there was also a 0.5-fold decrease in sEH protein level for the 50 mM mannitol osmolarity control. These results require further replication. The hypoxia experiment is expected to show higher levels of sEH than the normoxia control and the mRNA expression analyses are underway.
 Conclusion and Potential Impact: The results from this study suggest that hyperglycemic conditions can upregulate sEH expression in retinal pigment epithelial cells. Completion of this study will further our understanding of the underlying pathophysiology of DR.

Soluble Epoxide Hydrolase Plays a Vital Role in Angiotensin II-Induced Lung Injury in Mice.

Angiotensin II plays a vital role in the pathogenesis of acute respiratory distress syndrome (ARDS). However, its mechanism is not well defined. Angiotensin II upregulates the expression of soluble epoxide hydrolase (sEH; Ephx2). sEH is suggested as a potential pharmacologic target for ARDS. The present study investigates whether the sEH is involved in the angiotensin II-triggered pulmonary inflammation and edema using an angiotensin II-induced lung injury animal model. Lung injury was induced by angiotensin II intratracheally instillation in wild-type or Ephx2 deficient mice. sEH activities were markedly increased in wild-type mice treated with angiotensin II. Angiotensin II markedly increased the levels of tumor necrosis factor-α and interleukin-1β in bronchoalveolar lavage fluid, worsened alveolar capillary protein leak and lung histological alterations, and elevated activity of activator protein-1 and nuclear factor-κB. However, these changes were significantly improved in Ephx2 deficient mice. Moreover, Losartan, an angiotensin II receptor 1 antagonist, abolished the sEH induction and improved mortality. Angiotensin II-induced lung injury was improved in sEH gene deleted mice. The angiotensin II-triggered pulmonary inflammation is mediated, at least in part, through the sEH.

Expression of soluble epoxide hydrolase in renal tubular epithelial cells regulates macrophage infiltration and polarization in IgA nephropathy.

Tubulointerstitial inflammatory cell infiltration and activation contribute to kidney inflammation and fibrosis. Epoxyeicosatrienoic acids (EETs), which are rapidly metabolized to dihydroxyeicosatrienoic acids by the soluble epoxide hydrolase (sEH), have multiple biological functions, including vasodilation, anti-inflammatory action, and others. Inhibition of sEH has been demonstrated to attenuate inflammation in many renal disease models. However, the relationship between sEH expression and macrophage polarization in the kidney remains unknown. In this study, we investigated the relationships between the level of sEH and clinical and pathological parameters in IgA nephropathy. The level of sEH expression positively correlated with proteinuria and infiltration of macrophages. sEH-positive tubules were found to be surrounded by macrophages. Furthermore, we found that incubation of immortalized human proximal tubular HK-2 cells with total urinary protein and overexpression of sEH promoted inflammatory factor production, which was associated with M1 polarization. We also exposed RAW264.7 mouse leukemic monocytes/macrophages to different HK-2 cell culture media conditioned by incubation with various substances affecting sEH amount or activity. We found that the upregulation of sEH promoted M1 polarization. However, pharmacological inhibition of sEH and supplementation with EETs reversed the conditioning effects of urinary proteins by inhibiting M1 polarization through the NF-κB pathway and stimulating M2 polarization through the phosphatidylinositol 3-kinase pathway. These data suggest that inhibition of sEH could be a new strategy to prevent the progression of inflammation and to attenuate renal tubulointerstitial fibrosis.

Lipidomic profiling reveals soluble epoxide hydrolase as a therapeutic target of obesity-induced colonic inflammation

Obesity is associated with enhanced colonic inflammation, which is a major risk factor for colorectal cancer. Considering the obesity epidemic in Western countries, it is important to identify novel therapeutic targets for obesity-induced colonic inflammation, to develop targeted strategies for prevention. Eicosanoids are endogenous lipid signaling molecules involved in regulating inflammation and immune responses. Using an LC-MS/MS-based lipidomics approach, we find that obesity-induced colonic inflammation is associated with increased expression of soluble epoxide hydrolase (sEH) and its eicosanoid metabolites, termed fatty acid diols, in colon tissue. Furthermore, we find that pharmacological inhibition or genetic ablation of sEH reduces colonic concentrations of fatty acid diols, attenuates obesity-induced colonic inflammation, and decreases obesity-induced activation of Wnt signaling in mice. Together, these results support that sEH could be a novel therapeutic target for obesity-induced colonic inflammation and associated diseases.

Lipidomic Profiling Reveals Soluble Epoxide Hydrolase As a Therapeutic Target of Obesity‐induced Colonic Inflammation

Obesity is associated with enhanced colonic inflammation, which is a major risk factor of colorectal cancer. Considering the obesity epidemic in United States, there is an urgent need to identify novel therapeutic targets for obesity‐induced colonic inflammation. Eicosanoids are endogenous lipid signaling molecules involved in regulating inflammation and immune responses. Using a LC‐MS/MS‐based lipidomics approach, we found that obesity‐induced colonic inflammation is associated with increased expression of soluble epoxide hydrolase (sEH) and its eicosanoid metabolites, termed fatty acid diols, in colon tissue. To study the functional role of sEH, we treated mice with sEH inhibitors, TPPU or t‐TUCB, in high fat diet (HFD)‐induce obesity model, and found that pharmacological inhibition of sEH attenuated obesity‐induced colonic inflammation. Administration of sEH inhibitors diminished obesity‐induced infiltration of immune cells and expressions of pro‐inflammatory cytokines in colon tissue. Furthermore, we examined the sEH−/− mice in obesity model, and found genetic ablation of sEH reduced colonic concentrations of fatty acid diols and decreased the expressions of pro‐inflammatory cytokines. Finally, HFD treatment increased expression of phosphorylated GSK3β in colon tissue, while such effect was attenuated in sEH−/− mice, or by treatment with sEH inhibitors, suggesting that pharmacological inhibition and genetic ablation of sEH attenuated HFD‐induced activation of Wnt signaling in colon. Together, these results support that sEH could be a novel therapeutic target for obesity‐induced colonic inflammation and associated diseases.Support or Funding InformationThis work was supported by USDA NIFA grants 2016‐67017‐24423 and 2014‐67017‐21762, NIEHS grant R01 ES002710 and NIEHS Superfund Research Program P42 ES004699, and National Natural Science Foundation of China (NSFC) grants 81702832, 81672938 and 81470588.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Pharmacological inhibition or genetic ablation of soluble epoxide hydrolase attenuates obesity‐induced nonalcoholic fatty liver disease

The prevalence of nonalcoholic fatty liver disease (NAFLD) in western countries is 20–30%; it is of critical importance to identify new therapeutic target, in order to reduce the risks of NAFLD and associated diseases. Here, we report that the expression of soluble epoxide hydrolase (sEH) is increased in liver tissues of a high‐fat diet‐induced NAFLD model; in addition, pharmacological inhibition or genetic ablation of sEH attenuates high‐fat diet‐induced NAFLD, suggesting that sEH could be a novel therapeutic target of NAFLD. We find that after 8‐week dietary feeding of high‐fat diet (60%cal), the expression of sEH is dramatically increased in liver. To explore the roles of sEH in obesity‐induced NAFLD, we test whether pharmacological inhibition or genetic ablation of sEH affects the development of NAFLD. We find that oral administration of TPPU and t‐TUCB, which are two different sEH inhibitors, attenuates high‐fat diet‐induced fat accumulation in liver (assess by liver triglyceride analysis, oil red o staining and H&E histology staining), and reduces expressions of pro‐inflammatory genes in liver (Mcp‐1 and Tnf‐α). Similar results are observed in sEH knockout mice. Regarding the mechanisms, we find that pharmacological inhibition or genetic ablation of sEH suppresses the expression of Srebf1, Ppar‐γ, Cd36 and Dgat2, which play critical roles in lipid synthesis; and increases the expression of Ppar‐α, regulating fatty acid β‐oxidation. Together, these results support that sEH could be a promising therapeutic target for NAFLD, suppressing fat accumulation and inflammation in liver. This could lead to rapid human translations, because the pharmacological inhibitors of sEH are being evaluated in human clinical trials targeting multiple disorders.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

EET‐agonist Prevents and Reverses Heart Failure in Obesity Induced Diabetic Cardiomyopathy

Previously we demonstrated that an EET‐agonist has pleiotropic effects including inhibition of Soluble Epoxide Hydrolase expression and reversed cardiomyopathy by decreasing inflammatory molecules and increasing antioxidant signaling. We hypothesized that an EET agonist would increase PGC‐1α, which controls mitochondrial function and HO‐1 induction and negatively regulates the expression of the proinflammatory adipokine NOV in both cardiac and pericardial tissues. This pathway would be expected to further improve left ventricular systolic function as well as increase insulin receptor phosphorylation. The effect of an EET agonist was measured in cardiac and pericardial adipose tissues in db/db mice on oxygen consumption, fractional shortening, blood glucose levels, thermogenic and mitochondrial signaling proteins. Control db/db mice developed signs of metabolic syndrome including insulin resistance, hypertension, inflammation, LV dysfunction, and increased NOV expression in pericardial adipose tissue. EET agonist decreased pericardial adipose tissue expression of NOV, normalized FS, increased PGC‐1α, HO‐1 levels, insulin receptor phosphorylation and improved mitochondrial function. HO‐1‐ derived carbon monoxide (CO) levels, mitochondrial function (p<0.01), insulin receptor phosphorylation (p<0.05), ATP levels and VO2 (p<0.05). Deletion of PGC‐1α reversed all of the above beneficial effects, increasing the expression of NOV and inflammatory cytokines in pericardial adipose tissue. These studies demonstrate that an EET agonist increases insulin receptor phosphorylation, mitochondrial and thermogenic gene expression, decreases cardiac and pericardial tissue NOV levels, and ameliorates cardiomyopathy in an obese mouse model of the metabolic syndrome. Further, this study demonstrated that EET‐mediated inhibition of NOV is a potential therapeutic target for the prevention of heart failure and the development of metabolic syndrome.Support or Funding InformationNational Institutes of Health grant (HL34300 to NGA)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Increased epoxyeicosatrienoic acids may be part of a protective mechanism in human ulcerative colitis, with increased CYP2J2 and reduced soluble epoxide hydrolase expression

BackgroundPrevious preclinical evidence has suggested that the elevation of epoxyeicosatrienoic acids (EETs) derived from the cytochrome P450 (CYP) epoxygenases-dependent metabolism of arachidonic acid has important anti-inflammatory effects. However, the levels of EETs and their synthetic and metabolic enzymes in human ulcerative colitis has not been evaluated. MethodTo evaluate EETs and the expression of relevant CYP isoforms and the metabolizing enzyme, soluble epoxide hydrolase (sEH), tissue biopsies were collected from 16 pairs of ulcerative colitis patients’ tissues and matched with adjacent non-inflamed tissues. EETs were extracted from tissue homogenates and analyzed by liquid chromatography coupled with tandem mass spectrometry. ResultsThe concentration of EETs was higher in ulcerative colitis tissues compared with matched adjacent non-inflamed tissues (1.91 ± 0.98 ng/mg vs. 0.96 ± 0.77 ng/mg, mean ± SD, P < 0.01). As shown by immunohistochemistry, sEH was present in the cytoplasm and intestinal mucosa and showed a decline in ulcerative colitis tissues compared with matched adjacent non-inflamed tissues. Western blot analyses showed reduced sEH expression in ulcerative colitis tissues compared with matched adjacent non-inflamed tissues, whereas CYP2J2 increased in ulcerative colitis tissues (P < 0.05). However, there was no statistically significant difference observed in CYP2C8 and CYP2C9 protein expression between them (P > 0.05). ConclusionOur data suggest that the increase in EET levels may be part of a protective mechanism in ulcerative colitis. Furthermore, the concentration of EETs could be a key factor for drug therapy for ulcerative colitis.

Reduced coronary reactive hyperemia in mice was reversed by the soluble epoxide hydrolase inhibitor (t-AUCB): Role of adenosine A2A receptor and plasma oxylipins

Coronary reactive hyperemia (CRH) protects the heart against ischemia. Adenosine A2AAR–deficient (A2AAR−/−) mice have increased expression of soluble epoxide hydrolase (sEH); the enzyme responsible for breaking down the cardioprotective epoxyeicosatrienoic acids (EETs) to dihydroxyeicosatrienoic acids (DHETs). sEH–inhibition enhances CRH, increases EETs, and modulates oxylipin profiles. We investigated the changes of oxylipins and their impact on CRH in A2AAR−/− and wild type (WT) mice. We hypothesized that the attenuated CRH in A2AAR−/− mice is mediated by changes in oxylipin profiles, and that it can be reversed by either sEH- or ω-hydroxylases–inhibition. Compared to WT mice, A2AAR−/− mice had attenuated CRH and changed oxylipin profiles, which were consistent between plasma and heart perfusate samples, including decreased EET/DHET ratios, and increased hydroxyeicosatetraenoic acids (HETEs). Plasma oxylipns in A2AAR−/− mice indicated an increased proinflammatory state including increased ω-terminal HETEs, decreased epoxyoctadecaenoic/dihydroxyoctadecaenoic acids (EpOMEs/DiHOMEs) ratios, increased 9-hydroxyoctadecadienoic acid, and increased prostanoids. Inhibition of either sEH or ω-hydroxylases reversed the reduced CRH in A2AAR−/− mice. In WT and sEH−/− mice, blocking A2AAR decreased CRH. These data demonstrate that A2AAR–deletion was associated with changes in oxylipin profiles, which may contribute to the attenuated CRH. Also, inhibition of sEH and ω-hydroxylases reversed the reduction in CRH.

N-3 Polyunsaturated Fatty Acids Decrease the Protein Expression of Soluble Epoxide Hydrolase via Oxidative Stress-Induced P38 Kinase in Rat Endothelial Cells.

N-3 polyunsaturated fatty acids (PUFAs) improve endothelial function. The arachidonic acid-derived metabolites (epoxyeicosatrienoic acids (EETs)) are part of the endothelial hyperpolarization factor and are vasodilators independent of nitric oxide. However, little is known regarding the regulation of EET concentration by docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in blood vessels. Sprague-Dawley rats were fed either a control or fish oil diet for 3 weeks. Compared with the control, the fish oil diet improved acetylcholine-induced vasodilation and reduced the protein expression of soluble epoxide hydrolase (sEH), a key EET metabolic enzyme, in aortic strips. Both DHA and EPA suppressed sEH protein expression in rat aorta endothelial cells (RAECs). Furthermore, the concentration of 4-hydroxy hexenal (4-HHE), a lipid peroxidation product of n-3 PUFAs, increased in n-3 PUFA-treated RAECs. In addition, 4-HHE treatment suppressed sEH expression in RAECs, suggesting that 4-HHE (derived from n-3 PUFAs) is involved in this phenomenon. The suppression of sEH was attenuated by the p38 kinase inhibitor (SB203580) and by treatment with the antioxidant N-acetyl-L-cysteine. In conclusion, sEH expression decreased after n-3 PUFAs treatment, potentially through oxidative stress and p38 kinase. Mild oxidative stress induced by n-3 PUFAs may contribute to their cardio-protective effect.

A diet rich in omega-3 fatty acids enhances expression of soluble epoxide hydrolase in murine brain

Several studies suggest that intake of omega-3 polyunsaturated fatty acids (n3-PUFA) beneficially influences cognitive function. However, effects on the adult brain are not clear. Little is known about the impact of dietary intervention on the fatty acid profile in adult brain, the modulation in the expression of enzymes involved in fatty acid biosynthesis and metabolism as well as changes in resulting oxylipins. These questions were addressed in the present study in two independent n3-PUFA feeding experiments in mice. Supplementation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA, 1% each in the diet) for 30days to adult NMRI and C57BL/6 mice led to a distinct shift in the brain PUFA pattern. While n3-PUFAs EPA, n3 docosapentaenoic acid and DHA were elevated, many n6-PUFAs were significantly decreased (except, e.g. C20:3 n6 which was increased). This shift in PUFAs was accompanied by immense differences in concentrations of oxidative metabolites derived from enzymatic conversion of PUFAs, esp. arachidonic acid whose products were uniformly decreased, and a modulation in the activity and expression pattern of delta-5 and delta-6 desaturases. In both mouse strains a remarkable increase in the soluble epoxide hydrolase (sEH) activity (decreased epoxy-FA concentrations and epoxy-FA to dihydroxy-FA–ratios) as well as sEH expression was observed. Taking the high biological activity of epoxy-FA, e.g. on blood flow and nociceptive signaling into account, this finding might be of relevance for the effects of n3-PUFAs in neurodegenerative diseases. On any account, our study suggests a new distinct regulation of brain PUFA and oxylipin pattern by supplementation of n3-PUFAs to adult rodents.

Lipidomic Profiling Identifies Cytochrome P450 as A Therapeutic Target for Colitis‐Associated Colorectal Cancer

Eicosanoids and associated lipid mediators play central roles in regulating inflammation and carcinogenesis. While most previous studies of lipid mediators in colorectal cancer have only analyzed single or limited number of lipid mediators, few systematic studies have been carried out. Here we used a LC‐MS/MS‐based lipidomics, which can analyze &gt;100 bioactive lipid mediators produced by cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome P450 (CYP) enzymes, to profile azoxymethane (AOM)/dextran sulfate sodium (DSS)‐induced colorectal cancer in mice. Lipidomics showed that CYP‐derived fatty acid epoxides were the only lipid mediators which were increased in both plasma and colon tissues of AOM/DSS‐treated mice. RT‐PCR and western blotting validated that the expressions of CYP were increased, while the expression of soluble epoxide hydrolase (the dominant enzyme in degrading fatty acid epoxides) was reduced, in colon tissues of AOM/DSS‐treated mice. To study the functional roles of CYP enzymes, we treated mice with SKF‐525A and clotrimazole, which are two different selective inhibitors of CYP enzymes involved in biosynthesis of fatty acid epoxides, and found that CYP inhibitors significantly suppressed AOM/DSS‐induced colorectal cancer in mice. To elucidate the specific lipid mediator involved in the pro‐colorectal cancer effects of CYP, we treated mice with epoxyoctadecenoic acids (EpOMEs) which are metabolites of linoleic acid produced by CYP, and found that EpOMEs worsened DSS‐induced colitis. Together, these results suggest that the previously unappreciated CYP pathway plays critical roles in promoting progression of colorectal cancer through formation of pro‐inflammatory EpOMEs, and CYP enzymes could be novel therapeutic targets of colitis‐associated colorectal cancer.Support or Funding InformationUSDA NIFA 2016‐67017‐24423, NIEHS R01 ES002710 and Superfund Research Program P42 ES04699

Epoxyeicosatrienoic acids and glucose homeostasis in mice and men

Epoxyeicosatrienoic acids (EETs) are formed from arachidonic acid by the action of P450 epoxygenases (CYP2C and CYP2J). Effects of EETs are limited by hydrolysis by soluble epoxide hydrolase to less active dihydroxyeicosatrienoic acids. Studies in rodent models provide compelling evidence that epoxyeicosatrienoic acids exert favorable effects on glucose homeostasis, either by enhancing pancreatic islet cell function or by increasing insulin sensitivity in peripheral tissues. Specifically, the tissue expression of soluble epoxide hydrolase appears to be increased in rodent models of obesity and diabetes. Pharmacological inhibition of epoxide hydrolase or deletion of the gene encoding soluble epoxide hydrolase (Ephx2) preserves islet cells in rodent models of type 1 diabetes and enhances insulin sensitivity in models of type 2 diabetes, as does administration of epoxyeicosatrienoic acids or their stable analogues. In humans, circulating concentrations of epoxyeicosatrienoic acids correlate with insulin sensitivity, and a loss-of-function genetic polymorphism in EPHX2 is associated with insulin sensitivity.

Increased epoxyeicosatrienoic acids and reduced soluble epoxide hydrolase expression in the preeclamptic placenta.

Epoxyeicosatrienoic acids (EETs) derived from cytochrome P450 (CYP)-dependent metabolism of arachidonic acid are increased in the plasma of women with preeclampsia as compared with normal pregnancy and are significantly higher in fetal than in maternal plasma and erythrocytes. We hypothesized that differences in EET synthesis or metabolism in the feto-placental unit contributed to the observed differences in circulating EETs. To evaluate EETs, formation as well as the expression of relevant CYP isoforms and the metabolizing enzyme, soluble epoxide hydrolase (sEH), biopsies of placenta were collected from 19 normal pregnancy and 10 preeclampsia at the time of cesarean section delivery. EETs were extracted from tissue homogenates and analyzed by liquid chromatography coupled with tandem mass spectrometry. Both cis-EETs and trans-EETs were detected in the placenta. Concentration of total EETs was higher in the placenta from preeclampsia compared with normal pregnancy (2.37 ± 1.42 ng/mg vs. 1.20 ± 0.72 ng/mg, mean ± SD, P < 0.01), especially the 5,6-, 8,9- and 11,12-EETs, measured in a subgroup of tissue samples (normal pregnancy = 10, preeclampsia = 5). By immunohistochemistry, sEH, CYP2J2, CYP4A11 were present in placental villi with different pattern distribution, whereas CYP2C8 was not detectable. Neither were CYP2J2, CYP4A11, and CYP2C8 detected in the umbilical cord. Western blot analysis of placenta homogenates showed reduced expression of sEH in preeclampsia as compared with normal pregnancy. Increased EETs in the placenta and umbilical cord are associated with the presence of CYP2J2, whereas reduced expression of sEH in preeclampsia may be the key factor of increased EETs in the placenta.