Opposite effects of gene deficiency and pharmacological inhibition of soluble epoxide hydrolase on cardiac fibrosis. Li Lijuan,Li Nan,Pang Wei,Zhang Xu,Hammock Bruce D,Ai Ding,Zhu Yi PloS one Arachidonic acid-derived epoxyeicosatrienoic acids (EETs) are important regulators of cardiac remodeling; manipulation of their levels is a potentially useful pharmacological strategy. EETs are hydrolyzed by soluble epoxide hydrolase (sEH) to form the corresponding diols, thus altering and reducing the activity of these oxylipins. To better understand the phenotypic impact of sEH disruption, we compared the effect of EPHX2 gene knockout (EPHX2-/-) and sEH inhibition in mouse models. Measurement of plasma oxylipin profiles confirmed that the ratio of EETs/DHETs was increased in EPHX2-/- and sEH-inhibited mice. However, plasma concentrations of 9, 11, 15, 19-HETE were elevated in EPHX2-/- but not sEH-inhibited mice. Next, we investigated the role of this difference in cardiac dysfunction induced by Angiotensin II (AngII). Both EPHX2 gene deletion and inhibition protected against AngII-induced cardiac hypertrophy. Interestingly, cardiac dysfunction was attenuated by sEH inhibition rather than gene deletion. Histochemical staining revealed that compared with pharmacological inhibition, EPHX2 deletion aggravated AngII-induced myocardial fibrosis; the mRNA levels of fibrotic-related genes were increased. Furthermore, cardiac inflammatory response was greater in EPHX2-/- than sEH-inhibited mice with AngII treatment, as evidenced by increased macrophage infiltration and expression of MCP-1 and IL-6. In vitro, AngII-upregulated MCP-1 and IL-6 expression was significantly attenuated by sEH inhibition but promoted by EPHX2 deletion in cardiofibroblasts. Thus, compared with pharmacological inhibition of sEH, EPHX2 deletion caused the shift in arachidonic acid metabolism, which may led to pathological cardiac remodeling, especially cardiac fibrosis. 10.1371/journal.pone.0094092

Epoxide hydrolase 1 (EPHX1) hydrolyzes epoxyeicosanoids and impairs cardiac recovery after ischemia. Edin Matthew L,Hamedani Behin Gholipour,Gruzdev Artiom,Graves Joan P,Lih Fred B,Arbes Samuel J,Singh Rohanit,Orjuela Leon Anette C,Bradbury J Alyce,DeGraff Laura M,Hoopes Samantha L,Arand Michael,Zeldin Darryl C The Journal of biological chemistry Stimuli such as inflammation or hypoxia induce cytochrome P450 epoxygenase-mediated production of arachidonic acid-derived epoxyeicosatrienoic acids (EETs). EETs have cardioprotective, vasodilatory, angiogenic, anti-inflammatory, and analgesic effects, which are diminished by EET hydrolysis yielding biologically less active dihydroxyeicosatrienoic acids (DHETs). Previous assays have suggested that epoxide hydrolase 2 (EPHX2) is responsible for nearly all EET hydrolysis. EPHX1, which exhibits slow EET hydrolysis , is thought to contribute only marginally to EET hydrolysis. Using , , and mice, we show here that EPHX1 significantly contributes to EET hydrolysis Disruption of and/or genes did not induce compensatory changes in expression of other genes or family epoxygenases. Plasma levels of 8,9-, 11,12-, and 14,15-DHET were reduced by 38, 44, and 67% in mice compared with wildtype (WT) mice, respectively; however, plasma from mice exhibited significantly greater reduction (100, 99, and 96%) of those respective DHETs. Kinetic assays and FRET experiments indicated that EPHX1 is a slow EET scavenger, but hydrolyzes EETs in a coupled reaction with cytochrome P450 to limit basal EET levels. Moreover, we also found that EPHX1 activities are biologically relevant, as hearts had significantly better postischemic functional recovery (71%) than both WT (31%) and (51%) hearts. These findings indicate that mice are a valuable model for assessing EET-mediated effects, uncover a new paradigm for EET metabolism, and suggest that dual EPHX1 and EPHX2 inhibition may represent a therapeutic approach to manage human pathologies such as myocardial infarction. 10.1074/jbc.RA117.000298

Altered soluble epoxide hydrolase gene expression and function and vascular disease risk in the stroke-prone spontaneously hypertensive rat. Corenblum Mandi J,Wise Vance E,Georgi Katrin,Hammock Bruce D,Doris Peter A,Fornage Myriam Hypertension (Dallas, Tex. : 1979) Soluble epoxide hydrolase (sEH) metabolizes epoxyeicosatrienoic acids and represents a novel therapeutic target in cardiovascular disease treatment. We investigated the relationship among sequence variation in the sEH gene (Ephx2), sEH function, and risk of end-organ injury in strains of spontaneously hypertensive rat (SHRs) differing in their susceptibility to develop brain vascular disease. Brain Ephx2 expression was significantly lower in stroke-prone (SHR/A3) than in stroke-resistant (SHR/N) SHRs (5-fold; P<0.0001). Resequencing of the Ephx2 promoter in the 2 strains identified 3 polymorphisms that significantly influenced promoter transcriptional activity in vitro. Measurements of brain sEH enzyme activity and plasma levels of arachidonate and linoleate metabolites of sEH further suggested significant differences between the 2 strains. Ratios of epoxyoctadecenoic acids to dihydroxyoctadecenoic acids were significantly higher, indicating a lower sEH activity in SHR/A3 than in SHR/N (P<0.0001). Plasma dihydroxyeicosatrienoic acid levels were lower in SHR/A3 than in SHR/N (P<0.0001), but plasma epoxyeicosatrienoic acids levels were similar in the 2 strains. Association analysis of Ephx2 polymorphism in the F2 progeny of an SHR/A3xSHR/N cross showed that animals carrying the SHR/A3 allele of Ephx2 had a greater risk of stroke and associated urinary proteinuria than animals that do not. Investigation of patterns of allelic similarities and differences among multiple stroke-prone and stroke-resistant SHR substrains showed that Ephx2 belongs to a haplotype block shared among all of the stroke-prone but no stroke-resistant substrains. These data support a role for Ephx2 polymorphism on sEH gene expression and function and risk of end-organ injury in the stroke-prone SHR. 10.1161/HYPERTENSIONAHA.107.102160

Vascular Lipidomic Profiling of Potential Endogenous Fatty Acid PPAR Ligands Reveals the Coronary Artery as Major Producer of CYP450-Derived Epoxy Fatty Acids. Cells A number of oxylipins have been described as endogenous PPAR ligands. The very short biological half-lives of oxylipins suggest roles as autocrine or paracrine signaling molecules. While coronary arterial atherosclerosis is the root of myocardial infarction, aortic atherosclerotic plaque formation is a common readout of in vivo atherosclerosis studies in mice. Improved understanding of the compartmentalized sources of oxylipin PPAR ligands will increase our knowledge of the roles of PPAR signaling in diverse vascular tissues. Here, we performed a targeted lipidomic analysis of ex vivo-generated oxylipins from porcine aorta, coronary artery, pulmonary artery and perivascular adipose. Cyclooxygenase (COX)-derived prostanoids were the most abundant detectable oxylipin from all tissues. By contrast, the coronary artery produced significantly higher levels of oxylipins from CYP450 pathways than other tissues. The TLR4 ligand LPS induced prostanoid formation in all vascular tissue tested. The 11-HETE, 15-HETE, and 9-HODE were also induced by LPS from the aorta and pulmonary artery but not coronary artery. Epoxy fatty acid (EpFA) formation was largely unaffected by LPS. The pig CYP2J homologue CYP2J34 was expressed in porcine vascular tissue and primary coronary artery smooth muscle cells (pCASMCs) in culture. Treatment of pCASMCs with LPS induced a robust profile of pro-inflammatory target genes: and . The soluble epoxide hydrolase inhibitor TPPU, which prevents the breakdown of endogenous CYP-derived EpFAs, significantly suppressed LPS-induced inflammatory target genes. In conclusion, PPAR-activating oxylipins are produced and regulated in a vascular site-specific manner. The CYP450 pathway is highly active in the coronary artery and capable of providing anti-inflammatory oxylipins that prevent processes of inflammatory vascular disease progression. 10.3390/cells9051096

Inhibition of soluble epoxide hydrolase attenuates renal tubular mitochondrial dysfunction and ER stress by restoring autophagic flux in diabetic nephropathy. Jiang Xu-Shun,Xiang Xing-Yang,Chen Xue-Mei,He Jun-Ling,Liu Ting,Gan Hua,Du Xiao-Gang Cell death & disease Diabetic nephropathy (DN) is the leading cause of end-stage renal disease (ESRD), and renal tubular cell dysfunction contributes to the pathogenesis of DN. Soluble epoxide hydrolase (sEH) is an enzyme that can hydrolyze epoxyeicosatrienoic acids (EETs) and other epoxy fatty acids (EpFAs) into the less biologically active metabolites. Inhibition of sEH has multiple beneficial effects on renal function, however, the exact role of sEH in hyperglycemia-induced dysfunction of tubular cells is still not fully elucidated. In the present study, we showed that human proximal tubular epithelial (HK-2) cells revealed an upregulation of sEH expression accompanied by the impairment of autophagic flux, mitochondrial dysfunction, ubiquitinated protein accumulation and enhanced endoplasmic reticulum (ER) stress after high glucose (HG) treatment. Furthermore, dysfunctional mitochondria accumulated in the cytoplasm, which resulted in excessive reactive oxygen species (ROS) generation, Bax translocation, cytochrome c release, and apoptosis. However, t-AUCB, an inhibitor of sEH, partially reversed these negative outcomes. Moreover, we also observed increased sEH expression, impaired autophagy flux, mitochondrial dysfunction and enhanced ER stress in the renal proximal tubular cells of db/db diabetic mice. Notably, inhibition of sEH by treatment with t-AUCB attenuated renal injury and partially restored autophagic flux, improved mitochondrial function, and reduced ROS generation and ER stress in the kidneys of db/db mice. Taken together, these results suggest that inhibition of sEH by t-AUCB plays a protective role in hyperglycemia-induced proximal tubular injury and that the potential mechanism of t-AUCB-mediated protective autophagy is involved in modulating mitochondrial function and ER stress. Thus, we provide new evidence linking sEH to the autophagic response during proximal tubular injury in the pathogenesis of DN and suggest that inhibition of sEH can be considered a potential therapeutic strategy for the amelioration of DN. 10.1038/s41419-020-2594-x