20-Hydroxyeicosatetraenoic acid (20-HETE) is a bioactive lipid generated from the ω-hydroxylation of arachidonic acid (AA) by enzymes of the cytochrome P450 (CYP) family, primarily the CYP4A and ...CYP4F subfamilies. 20-HETE is most notably identified as a modulator of vascular tone, regulator of renal function, and a contributor to the onset and development of hypertension and cardiovascular disease. 20-HETE-mediated signaling promotes hypertension by sensitizing the vasculature to constrictor stimuli, inducing endothelial dysfunction, and potentiating vascular inflammation. These bioactions are driven by the activation of the G-protein coupled receptor 75 (GPR75), a 20-HETE receptor (20HR). Given the capacity of 20-HETE signaling to drive pro-hypertensive mechanisms, the CYP/20-HETE/GPR75 axis has the potential to be a significant therapeutic target for the treatment of hypertension and cardiovascular diseases associated with increases in blood pressure. In this chapter, we review 20-HETE-mediated cellular mechanisms that promote hypertension, highlight important data in humans such as genetic variants in the CYP genes that potentiate 20-HETE production and describe recent findings in humans with 20HR/GPR75 mutations. Special emphasis is given to the 20HR and respective receptor blockers that have the potential to pave a path to translational and clinical studies for the treatment of 20-HETE-driven hypertension, and obesity/metabolic syndrome.
20-Hydroxyeicosatetraenoic acid (20-HETE) has been shown to positively correlate with body mass index, hyperglycemia, and plasma insulin levels. This study seeks to identify a causal relationship ...between 20-HETE and obesity-driven insulin resistance. Cyp4a14
male mice, a model of 20-HETE overproduction, were fed a regular or high-fat diet (HFD) for 15 wk. 20-SOLA 2,5,8,11,14,17-hexaoxanonadecan-19-yl 20-hydroxyeicosa-6( Z),15( Z)-dienoate, a 20-HETE antagonist, was administered from week 0 or week 7 of HFD. HFD-fed mice gained significant weight (16.7 ± 3.2 vs. 3.8 ± 0.35 g, P < 0.05) and developed hyperglycemia (157 ± 3 vs. 121 ± 7 mg/dl, P < 0.05) and hyperinsulinemia (2.3 ± 0.4 vs. 0.5 ± 0.1 ng/ml, P < 0.05) compared with regular diet-fed mice. 20-SOLA attenuated HFD-induced weight gain (9.4 ± 1 vs. 16.7 ± 3 g, P < 0.05) and normalized the hyperglycemia (157 ± 7 vs. 102 ± 5 mg/dl, P < 0.05) and hyperinsulinemia (1.1 ± 0.1 vs. 2.3 ± 0.4 ng/ml, P < 0.05). The impaired glucose homeostasis and insulin resistance in HFD-fed mice evidenced by reduced insulin and glucose tolerance were also ameliorated by 20-SOLA. Circulatory and adipose tissue 20-HETE levels significantly increased in HFD-fed mice correlating with impaired insulin signaling, including reduction in insulin receptor tyrosine (Y972) phosphorylation and increased serine (S307) phosphorylation of the insulin receptor substrate-1 (IRS-1). 20-SOLA treatments prevented changes in insulin signaling. These findings indicate that 20-HETE contributes to HFD-induced obesity, insulin resistance, and impaired insulin signaling.
The surface of the eye actively suppresses inflammation while maintaining a remarkable capacity for epithelial wound repair. Our understanding of mechanisms that balance inflammatory/reparative ...responses to provide effective host defense while preserving tissue function is limited, in particular, in the cornea. Lipoxin A4 (LXA4) and docosahexaenoic acid-derived neuroprotectin D1 (NPD1) are lipid autacoids formed by 12/15-lipoxygenase (LOX) pathways that exhibit anti-inflammatory and neuroprotective properties. Here, we demonstrate that mouse corneas generate endogenous LXA4 and NPD1. 12/15-LOX (Alox15) and LXA4 receptor mRNA expression as well as LXA4 formation were abrogated by epithelial removal and restored during wound healing. Amplification of these pathways by topical treatment with LXA4 or NPD1 (1 μg) increased the rate of re-epithelialization (65–90%, n = 6–10, p < 0.03) and attenuated the sequelae of thermal injury. In contrast, the proinflammatory eicosanoids, LTB4 and 12R-hydroxyeicosatrienoic acid, had no impact on corneal re-epithelialization. Epithelial removal induced a temporally defined influx of neutrophils into the stroma as well as formation of the proinflammatory chemokine KC. Topical treatment with LXA4 and NPD1 significantly increased PMNs in the cornea while abrogating KC formation by 60%. More importantly, Alox15-deficient mice exhibited a defect in both corneal re-epithelialization and neutrophil recruitment that correlated with a 43% reduction in endogenous LXA4 formation. Collectively, these results identify a novel action for the mouse 12/15-LOX (Alox15) and its products, LXA4 and NPD1, in wound healing that is distinct from their well established anti-inflammatory properties.
20-HETE, the ω-hydroxylation product of arachidonic acid catalyzed by enzymes of the cytochrome P450 (CYP) 4A and 4F gene families, is a bioactive lipid mediator with potent effects on the ...vasculature including stimulation of smooth muscle cell contractility, migration and proliferation as well as activation of endothelial cell dysfunction and inflammation. Clinical studies have shown elevated levels of plasma and urinary 20-HETE in human diseases and conditions such as hypertension, obesity and metabolic syndrome, myocardial infarction, stroke, and chronic kidney diseases. Studies of polymorphic associations also suggest an important role for 20-HETE in hypertension, stroke and myocardial infarction. Animal models of increased 20-HETE production are hypertensive and are more susceptible to cardiovascular injury. The current review summarizes recent findings that focus on the role of 20-HETE in the regulation of vascular and cardiac function and its contribution to the pathology of vascular and cardiac diseases.
20-Hydroxyeicosatetraenoic acid (20-HETE) has been linked to blood pressure (BP) regulation via actions on the renal microvasculature and tubules. We assessed the tubular 20-HETE contribution to ...hypertension by generating transgenic mice overexpressing the CYP4A12-20-HETE synthase (PT-4a12 mice) under the control of the proximal tubule (PT)-specific promoter phosphoenolpyruvate carboxykinase (PEPCK). 20-HETE levels in the kidney cortex of male (967 ± 210 vs. 249 ± 69 pg/mg protein) but not female (121 ± 15 vs. 92 ± 11 pg/mg protein) PT-4a12 mice showed a 2.5-fold increase compared with wild type (WT). Renal cortical Cyp4a12 mRNA and CYP4A12 protein in male but not female PT-4a12 mice increased by two- to threefold compared with WT. Male PT-4a12 mice displayed elevated BP (142 ± 1 vs. 111 ± 4 mmHg, P < 0.0001), whereas BP in female PT-4a12 mice was not significantly different from WT (118 ± 2 vs. 117 ± 2 mmHg; P = 0.98). In male PT-4a12 mice, BP decreased when mice were transitioned from a control-salt (0.4%) to a low-salt diet (0.075%) from 135 ± 4 to 120 ± 6 mmHg ( P < 0.01) and increased to 153 ± 5 mmHg ( P < 0.05) when mice were placed on a high-salt diet (4%). Female PT-4a12 mice did not show changes in BP on either low- or high-salt diet. In conclusion, the expression of Cyp4a12 driven by the PEPCK promoter is sex specific, probably because of its X-linkage. The salt-sensitive hypertension seen in PT-4a12 male mice suggests a potential antinatriuretic activity of 20-HETE that needs to be further explored.
Metabolic disorders such as obesity, insulin resistance and type 2 diabetes mellitus (DM2) are all linked to diabetic cardiomyopathy that lead to heart failure. Cardiomyopathy is initially ...characterized by cardiomyocyte hypertrophy, followed by mitochondrial dysfunction and fibrosis, both of which are aggravated by angiotensin. Caloric restriction (CR) is cardioprotective in animal models of heart disease through its catabolic activity and activation of the expression of adaptive genes. We hypothesized that in the diabetic heart; this effect involves antioxidant defenses and is mediated by SIRT1 and the transcriptional coactivator PGC-1α (Peroxisome proliferator-activated receptor-γ coactivator).
Obese Leptin resistant (db/db) mice characterized by DM2 were treated with angiotensin II (AT) for 4 weeks to enhance the development of cardiomyopathy. Mice were concomitantly either on a CR diet or fed ad libitum. Cardiomyocytes were exposed to high levels of glucose and were treated with EX-527 (SIRT1 inhibitor). Cardiac structure and function, gene and protein expression and oxidative stress parameters were analyzed.
AT treated db/db mice developed cardiomyopathy manifested by elevated levels of serum glucose, cholesterol and cardiac hypertrophy. Leukocyte infiltration, fibrosis and an increase in an inflammatory marker (TNFα) and natriuretic peptides (ANP, BNP) gene expression were also observed. Oxidative stress was manifested by low SOD and PGC-1α levels and an increase in ROS and MDA. DM2 resulted in ERK1/2 activation. CR attenuated all these deleterious perturbations and prevented the development of cardiomyopathy. ERK1/2 phosphorylation was reduced in CR mice (p = 0.008). Concomitantly CR prevented the reduction in SIRT activity and PGC-1α (p < 0.04). Inhibition of SIRT1 activity in cardiomyocytes led to a marked reduction in both SIRT1 and PGC-1α. ROS levels were significantly (p < 0.03) increased by glucose and SIRT1 inhibition.
In the current study we present evidence of the cardioprotective effects of CR operating through SIRT1 and PGC-1 α, thereby decreasing oxidative stress, fibrosis and inflammation. Our results suggest that increasing SIRT1 and PGC-1α levels offer new therapeutic approaches for the protection of the diabetic heart.
This study was aimed at obtaining a profile of lipids and proteins with a paracrine function in normal and diabetic vitreous and exploring whether the profile correlates with retinal pathology.
...Vitreous was recovered from 47 individuals undergoing vitreoretinal surgery: 16 had nonproliferative diabetic retinopathy (NPDR), 15 had proliferative diabetic retinopathy, 7 had retinal detachments, and 9 had epiretinal membranes. Protein and lipid autacoid profiles were determined by protein arrays and mass spectrometry-based lipidomics.
Vitreous lipids included lipoxygenase (LO)- and cytochrome P450 epoxygenase (CYP)-derived eicosanoids. The most prominent LO-derived eicosanoid was 5-hydroxyeicosate traenoic acid (HETE), which demonstrated a diabetes-specific increase (P = 0.027) with the highest increase in NPDR vitreous. Vitreous also contained CYP-derived epoxyeicosatrienoic acids; their levels were higher in nondiabetic than diabetic vitreous (P < 0.05). Among inflammatory, angiogenic, and angiostatic cytokines and chemokines, only vascular endothelial growth factor (VEGF) showed a significant diabetes-specific profile (P < 0.05), although a similar trend was noted for tumor necrosis factor (TNF)-alpha. Soluble VEGF receptors R1 and R2 were detected in all samples with lowest VEGF-R2 levels (P < 0.05) and higher ratio of VEGF to its receptors in NPDR and PDR vitreous.
This study is the first to demonstrate diabetes-specific changes in vitreous lipid autacoids including arachidonate and docosahexanoate-derived metabolites indicating an increase in inflammatory versus anti-inflammatory lipid mediators that correlated with increased levels of inflammatory and angiogenic proteins, further supporting the notion that inflammation plays a role the pathogenesis of this disease.
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19-Hydroxyeicosatetraenoic acid (19-HETE, 1), a metabolically and chemically labile cytochrome P450 eicosanoid, has diverse biological activities including antagonism of the ...vasoconstrictor 20-hydroxyeicosatetraenoic acid (20-HETE, 2). A SAR study was conducted to develop robust analogs of 1 with improved in vitro and in vivo efficacy. Analogs were screened in vitro for inhibition of 20-HETE-induced sensitization of rat renal preglomerular microvessels toward phenylephrine and demonstrated to normalize the blood pressure of male Cyp4a14(-/-) mice that display androgen-driven, 20-HETE-dependent hypertension.
OBJECTIVE—20-hydroxyeicosatetraenoic acid (20-HETE) promotes endothelial dysfunction by uncoupling endothelial NO synthase, stimulating O2 production, and reducing NO bioavailability. Moreover, ...20-HETE–dependent vascular dysfunction and hypertension are associated with upregulation of the renin–angiotensin system This study was undertaken to examine the contribution of renin–angiotensin system to 20-HETE actions in the vascular endothelium.
METHODS AND RESULTS—In endothelial cells, 20-HETE induced angiotensin-converting enzyme (ACE) mRNA levels and increased ACE protein and activity by 2- to 3-fold; these effects were negated with addition of the 20-HETE antagonist, 20-hydroxyeicosa-6(Z),15(Z)-dienoic acid (20 HEDE). 20-HETE induced ACE expression was protein kinase C independent and epidermal growth factor receptor tyrosine kinase and IκB kinase β dependent. ACE short interfering RNA abolished 20-HETE–mediated inhibition of NO production and stimulation of O2 generation, whereas angiotensin II type 1 receptor short interfering RNA attenuated these effects by 40%. 20-HETE–stimulated O2 production was negated by 20-HEDE and was attenuated by lisinopril and losartan. Importantly, 20-HETE–mediated impairment of acetylcholine-induced relaxation in rat renal interlobar arteries was also attenuated by lisinopril and losartan.
CONCLUSION—These results indicate that ACE and angiotensin II type 1 receptor activation contribute to 20-HETE–mediated endothelial cell and vascular dysfunction and further enforce the notion that excessive production of 20-HETE within the vasculature leads to hypertension via mechanisms that include the induction of endothelial ACE, thus, perpetuating an increase in vascular angiotensin which, together with 20-HETE, promotes vascular dysfunction.
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