20-HETE Levels Research Articles

Chronic exposure to cadmium is associated with a marked reduction in glomerular filtration rate.

BackgroundUrinary 20-hydroxyeicosatetraenoic acid (20-HETE) has been associated with hypertension in women with elevated urinary cadmium (Cd) excretion rates. The present study investigates the urinary Cd and 20-HETE levels in relation to the estimated glomerular filtration rate (eGFR) and albumin excretion in men and women. MethodsA population-based, cross-sectional study, which included 225 women and 84 men aged 33–55 years, was conducted in a rural area known to be polluted with Cd.ResultsIn all subjects, lower eGFR values were associated with higher urinary Cd excretion (P = 0.030), and tubulopathy markers N-acetyl-β-d-glucosaminidase (P < 0.001) and β2-microglobulin (β2-MG) (P < 0.001). On average, the hypertensive subjects with the highest quartile of urinary Cd had eGFR values of 12 and 17 mL/min/1.73 m2 lower than that in the hypertensive (P = 0.009) and normotensive subjects (P < 0.001) with the lowest quartile of urinary Cd, respectively. In men, urinary albumin was inversely associated with 20-HETE (β = −0.384, P < 0.001), while showing a moderately positive association with systolic blood pressure (SBP) (β = 0.302, P = 0.037). In women, urinary albumin was not associated with 20-HETE (P = 0.776), but was associated with tubulopathy, reflected by elevated urinary excretion of β2-MG (β = 0.231, P = 0.002).ConclusionsTubulopathy is a determinant of albumin excretion in women, while 20-HETE and SBP are determinants of urinary albumin excretion in men. Associations of chronic exposure to Cd with marked eGFR decline and renal tubular injury seen in both Cd-exposed men and women add to mounting research data that links Cd to the risk of developing chronic kidney disease.

High-fat diet-induced obesity and insulin resistance in CYP4a14-/- mice is mediated by 20-HETE.

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.

Elevated lipoxygenase and cytochrome P450 products predict progression of chronic kidney disease.

The clinical relevance of arachidonic acid (AA) metabolites in chronic kidney disease (CKD) progression is poorly understood. We aimed to compare the concentrations of 85 enzymatic pathway products of AA metabolism in patients with CKD who progressed to end-stage kidney disease (ESKD) versus patients who did not in a subcohort of Chronic Renal Insufficiency Cohort (CRIC) and to estimate the risk of CKD progression and major cardiovascular events by levels of AA metabolites and their link to enzymatic metabolic pathways. A total 123 patients in the CRIC study who progressed to ESKD were frequency matched with 177 nonprogressors and serum eicosanoids were quantified by mass spectrometry. We applied serum collected at patients' Year 1 visit and outcome of progression to ESKD was ascertained over the next 10 years. We used logistic regression models for risk estimation. Baseline 15-hydroxyeicosatetraenoate (HETE) and 20-HETE levels were significantly elevated in progressors (false discovery rate Q ≤ 0.026). The median 20-HETE level was 7.6 pmol/mL [interquartile range (IQR) 4.2-14.5] in progressors and 5.4 pmol/mL (IQR 2.8-9.4) in nonprogressors (P < 0.001). In an adjusted model, only 20-HETE independently predicted CKD progression. Each 1 standard deviation increase in 20-HETE was independently associated with 1.45-fold higher odds of progression (95% confidence interval 1.07-1.95; P = 0.017). Principal components of lipoxygenase (LOX) and cytochrome P450 (CYP450) pathways were independently associated with CKD progression. We found higher odds of CKD progression associated with higher 20-HETE, LOX and CYP450 metabolic pathways. These alterations precede CKD progression and may serve as targets for interventions aimed at halting progression.

20-HETE in the regulation of vascular and cardiac function.

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.

Partial loss of Ca2+‐Activated K+ channel (KCa) in Rat Cerebral Arterial Muscle in Insulin‐dependent diabetes mellitus

Cerebral arteries depolarize and constrict upon pressurization. This is one of the intrinsic mechanisms underlying autoregulation of cerebral blood flow (CBF). The Ca2+‐activated K+ channel (KCa) channel in arterial muscle is an important target through which cerebral arterial response to changes in endogenous or environmental stimulatory factors are sensed. The level of open state probability (NPo) of KCa channels determines the degree of myogenic tone and cytosolic Ca2+ concentration. In the present study we report impaired pressure‐dependent constriction of cerebral arteries and diminished density and NPo of KCa channel currents associated with reduced expression of KCa channel α‐ and β‐subunit proteins in cerebral arteries of genetically insulin‐dependent diabetic rats. In this study we also found that the expression of the CYP 4A ω‐hydroxylase protein and the production of 20‐HETE was significantly increased in the type 1 diabetic cerebral arteries compared to that in the non‐diabetic cerebral arteries. The observed changes in KCa channel function and expression of CYP 4A ω‐hydroxylase and production level of 20‐HETE could represent an important pathologic mechanisms that could underlie abnormalities in cerebral arterial reactivity in insulin‐dependent diabetes mellitus. It is concluded that the diminished KCa channel function, increased production of 20‐HETE and altered pressure‐dependent cerebral arterial constriction in insulin‐dependent diabetes mellitus may lead to impaired autoregulation of CBF that could contribute to increased risk of stroke in this disease condition.Support or Funding InformationNIH RO1 HL0338833This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Is renal tubular cadmium toxicity clinically relevant?

ABSTRACTBackgroundExposure to cadmium (Cd) has been associated with the development of hypertension, especially in women, but the mechanism of such an association is not understood. We hypothesize that Cd exposure alters renal production of 20-hydroxyeicosatetraenoic acid (20-HETE), which plays an indispensable role in renal salt balance and blood pressure control.MethodsWe examined long-term Cd exposure in relation to urinary 20-HETE excretion levels, tubular dysfunction and blood pressure measures, using data from a population-based, cross-sectional study that included 115 normotensive and 110 hypertensive women, 33–55 years of age, who lived in Cd contamination areas in Thailand.ResultsThe mean [standard deviation (SD)] blood Cd level of the study subjects was 3.57 (3.3) µg/L, while the mean (SD) urinary Cd and urinary 20-HETE levels were 0.58 (0.47) µg/g creatinine and 1651 (4793) pg/mL, respectively. Elevated 20-HETE levels were associated with a 90% increase in prevalence odds of hypertension (P = 0.029), four times greater odds of having higher urinary Cd levels (P = 0.030) and a 53% increase in odds of having higher levels of tubular dysfunction (P = 0.049), evident from an increase in urinary excretion of β2-microglobulin. In normotensive subjects, an increase in urinary 20-HETE levels from tertile 1 to tertile 3 was associated with a systolic blood pressure increase of 6 mmHg (95% confidence interval 0.3–12, P = 0.040).ConclusionsThis is the first report that links urinary 20-HETE levels to blood pressure increases in Cd-exposed women, thereby providing a plausible mechanism for associated development of hypertension.

Effect of 20-HETE inhibition on L-NAME-induced hypertension in rats

ABSTRACT20-Hydroxyeicosatetraenoicacid (20-HETE) is an important mediator that regulates vascular tone and blood pressure (BP). Although various experimental animal hypertension models demonstrated that 20-HETE contributes to increased vascular resistance and BP, these effects have not been studied in Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME)-induced hypertension model. In this study, we investigated the effects of 20-HETE on the vascular responsiveness and BP in an L-NAME-induced hypertension.Wistar Albino rats were used in this study. Hypertension was induced by the addition of L-NAME to drinking water for 5 weeks. The study was performed in three stages: first, BP changes were monitored in real time in the presence of 20-HETE enzymatic inhibitor, N-hydroxy-N´-(4-butly-2-methylphenyl)-formamidine (HET-0016) for 1 h. Second, vascular responses of the conduit and resistance arteries were investigated in the presence or absence of HET-0016 in the organ bath. Third, BP was monitored weekly in some hypertensive animals treated with HET-0016 and vascular responses were investigated at the end of the experiment.We demonstrated an increase in 20-HETE levels in the resistance arteries of hypertensive animals. 20-HETE inhibition by HET-0016 significantly decreased BP in L-NAME-induced hypertension model. In addition, HET-0016 treatment caused significant improvement in vascular dilator and constrictor responses in the conduit and resistance arteries.This study demonstrates an important role of 20-HETE in increasing BP and altering vascular responsiveness in L-NAME-induced hypertension model, which suggests a possible involvement of 20-HETE in essential hypertension development in humans.

Selective inhibition of 20-hydroxyeicosatetraenoic acid lowers blood pressure in a rat model of preeclampsia

Little is currently known of the role(s) of the vasoconstrictor 20-hydroxyeicosatetraenoic acid (20-HETE) in hypertensive pregnancies. We hypothesized that specific inhibition of 20-HETE would attenuate increases in blood pressure in the reduced uterine perfusion pressure (RUPP) rat model of preeclampsia. Specific 20-HETE synthesis inhibitor HET0016 (1mg/kg) was administered daily to RUPP rats from gestational days 14–18. Blood pressure (BP) increased in RUPP rats and was decreased with HET0016 administration. BP was unchanged in NP+HET0016 rats. Fetal death greatly increased in RUPP rats and was reduced in RUPP+HET0016 rats. 20-HETE levels increased modestly in RUPP rats compared to NP and was reduced in both NP+HET0016 and RUPP+HET0016 rats. Furthermore, circulating levels of HETEs, EET, and DHETE were significantly altered between groups. HET0016 shifted CYP metabolism toward EETs, as indicated by a decrease in plasma 20-HETE:EETs in RUPP+HET0016 rats compared to RUPP. In conclusion, 20-HETE inhibition in RUPP rats reduces BP and fetal death, and is associated with an increase in EET/20-HETE ratio.

Abstract P211: Intra-abdominal Lipectomy Normalizes Arterial Stiffness and Blood Pressure via Reduction in 20-HETE

Increased intra-abdominal (visceral) adipose tissue is a key feature of the metabolic syndrome affecting over 30% of the U.S. population. Expansion of visceral adipose tissue is linked to the development of hypertension and is a risk factor for cardiovascular disease that can ultimately lead to end-organ damage. While reduction in visceral adipose tissue volume offers cardioprotective effects, the cardiovascular mechanisms behind these beneficial effects remain unclear. In this study, we removed ~90% of visceral adipose tissue (=~5% body weight) by intra-abdominal lipectomy and assessed large arterial stiffness, large artery structural matrix components, and blood pressure in a metabolic syndrome rat model (JCR:LA-cp, JCR). Large artery stiffness was significantly elevated in JCR vs. normal (Sprague Dawley, SD) rats (75±2% JCR vs. SD (carotid)) with a concomitant significant increase in MMP12-dependent elastin degradation (3-6 fold vs. SD). Intra-abdominal lipectomy normalized large artery stiffness, blocked MMP12 activation and reduced elastin degradation in JCR animals (~75% (carotid) vs. untreated JCR). Likewise, hypertension in JCR animals was significantly attenuated by intra-abdominal lipectomy (MABP=156±3 mmHg JCR vs. 90±6 mmHg SD vs. 132±4 mmHg JCR+lipectomy). 20-hydroxyeicosatetraeonic acid (20-HETE), an arachidonic acid metabolite known to be a potent vasoconstrictor in resistance arteries, was significantly elevated in the visceral adipose tissue of JCR rats (~6 fold vs. SD). Intra-abdominal lipectomy normalized 20-HETE levels in JCR rats. Like intra-abdominal lipectomy, 20-HETE antagonists restored large artery elasticity, blocked MMP12 activation and elastin degradation, and significantly decreased blood pressure (125±3 mmHg JCR+20-HETE antagonists) in JCR rats. Thus, 20-HETE may be an important adipokine that mediates the adverse effects of expanded visceral fat volume in the metabolic syndrome and its inhibition may provide a pharmacological approach for the management of central obesity-driven large artery stiffness and hypertension.

Abstract P426: Suppression of Intrarenal Ras With a 20-hydroxyeicosatetraenoic Acid Antagonist Attenuates Ang II-dependent Malignant Hypertension and Reverses Established Ang-II-dependent Hypertension in Cyp1a1-ren-2 Transgenic Rats

Rationale and Objective: Interplay of 20-HETE and ANG II might be a factor in pathophysiology of many forms of experimental hypertension. We hypothesized that intrarenal 20-HETE potentiates prohypertensive actions of ANG II in Cyp1a1-Ren-2 transgenic rats (TGR), a model of ANG II-dependent malignant hypertension. Therefore, we evaluated the antihypertensive effectiveness of a new, orally active 20-HETE antagonist (SOLA) in this model. Methods: Treatment with SOLA (10 mg.kg -1 .day - 1 in drinking water) was started either simultaneously with induction of hypertension (early treatment) by indol-3-carbinol or 10 days later, during established hypertension (late treatment). Systolic blood pressure (SBP, measured by radiotelemetry) was monitored continuously and indices of renal and cardiac injury, and kidney 20-HETE and ANG II levels were determined at the end of experiments. Results: In TGR with induced hypertension, early SOLA treatment reduced SBP elevation (to 161±3 vs. 199±3 mmHg in induced TGR, p&lt;0.001), reduced albuminuria (16±2 vs. 35±3 mg/24 h, p&lt;0.002), glomerulosclerosis index (0.12±0.01 vs. 0.32±0.02, p&lt;0.001) and cardiac hypertrophy (left ventricle weight (mg)/tibial length ratio: 16.9±0.4 vs 20.6±0.5, p&lt;0.02). TGR with induced hypertension exhibited elevated intrarenal 20-HETE levels (15.2±0.03 vs. 9.2±0.02 μg/g in noninduced rats, p&lt;0.01); however, the elevation was not altered by SOLA treatment. Hypertensive TGR showed also augmented kidney ANG II levels (405±30 vs. 51±2 fmol/g in noninduced rats, p&lt;0.001). SOLA treatment significantly lowered kidney ANG II (95±19). Remarkably, in TGR with established hypertension, late SOLA treatment also decreased SBP (from 187±4 to 158±4 mmHg, p&lt;0.002) and exhibited cardio- and renoprotective effects in addition to a marked suppression of kidney ANG II levels (72±12 fmol/g). Conclusion: In hypertensive TGR the new orally active 20-HETE antagonist attenuated the development and largely reversed the established ANG II-dependent experimental malignant hypertension, likely via suppression of intrarenal ANG II levels. This suggests that intrarenal RAS activation by 20-HETE is important in pathophysiology of this hypertension form

Role of 20-Hydroxyeicosatetraenoic Acid (20-HETE) in Androgen-Mediated Cell Viability in Prostate Cancer Cells.

20-Hydroxyeicosatetraenoic acid (20-HETE) is generated intracellularly through the ω-hydroxylation of arachidonic acid by the cytochrome P450 (in humans, CYP4A11 and CYP4F2). 20-HETE induces mitogenic responses in different cancer cells. The aim of this study was to analyze how 20-HETE impacts cell survival, proliferation, and apoptosis in prostate cancer cells. Incubation of the human androgen-sensitive cells (LNCaP) with 1-10μM HET0016 (a selective inhibitor of 20-HETE synthesis) reduced cell viability by 49*-64%* (*p<0.05 vs. control). This was explained by a reduction in cell proliferation (vehicle, 46±3%; 1μM, 23±3%*; 10μM, 28±3%*) and by an increase in apoptosis (vehicle, 2.1±0%; 1μM, 16±4%*; 10μM, 31±3%*). Furthermore, the increase in LNCaP cell viability induced by dihydrotestosterone (DHT, 0.1nM) was abrogated by 30*-42%* by 1-10μM HET0016. Incubation with 20-HETE (5-1000nM) increased LNCaP cell viability up to 50%*, together with a 70%* reduction in apoptosis. PC-3 (androgen-insensitive) cell viability was not affected by either HET0016 or 20-HETE. In LNCaP cells, HET0016 (10μM) diminished the expression of androgen receptors (AR): messenger RNA (mRNA) (40%*) and protein (50%*). DHT (10nM) augmented CYP4F2 protein expression (1.9-fold*) and 20-HETE levels (50%*). Oppositely, enzalutamide (AR antagonist) reduced CYP4F2 mRNA and protein expressions by 30 and 25%, respectively. Thus, intracellular availability of 20-HETE is necessary to sustain LNCaP cell viability. 20-HETE may act as a signaling molecule in the pathways involved in LNCaP cell viability upon stimulation of the AR. This effect may be partially attributed to its role on securing normal AR expression levels that in turn contribute to maintain intracellular levels of 20-HETE.

Shexiang Baoxin pills promotes angiogenesis in myocardial infarction rats via up-regulation of 20-HETE-mediated endothelial progenitor cells mobilization

Background and aimsTherapeutic angiogenesis is a pivotal strategy for ischemic heart disease. The aim of the present study was to determine the effect and molecular mechanism of Shexiang Baoxin pills, a widely-used traditional Chinese medicine for ischemic heart disease, on angiogenesis in a rat model of myocardial infarction (MI). MethodsWe used the occlusion of left anterior descending coronary artery of Sprague-Dawley rats as a model of MI. The MI rats were treated with distilled water, Shexiang Baoxin pills, or Shexiang Baoxin pills + HET0016 (a selective blocker of the biosynthesis of 20-hydroxyeicosatetraenoic acid (20-HETE) at 10 mg/kg/day), respectively. Sham-operated rats were used as controls. ResultsTreatment with Shexiang Baoxin pills increases the level of serum 20-HETE in MI rats, which can be suppressed by HET0016 treatment. Shexiang Baoxin pills shows cardio-protective effects on MI rats, including improving cardiac function, decreasing infarction area, and promoting angiogenesis in peri-infarct area. The protective effects of Shexiang Baoxin pills are partly inhibited by HET0016. Furthermore, Shexiang Baoxin pills enhances the number of circulating endothelial progenitor cells (EPCs) and the expression of the vascular endothelial growth factor (VEGF), based on immunohistochemical analysis, in peri-infarct area of MI rats, which is partly suppressed by HET0016. ConclusionsShexiang Baoxin pills may partially participate in angiogenesis in MI rats. The protective mechanism of Shexiang Baoxin pills may be mediated via up-regulation of 20-HETE, which promotes EPCs mobilization and VEGF expression.

In This Issue

HomeCirculation ResearchVol. 120, No. 11In This Issue Free AccessIn BriefPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessIn BriefPDF/EPUBIn This Issue Ruth Williams Ruth WilliamsRuth Williams Search for more papers by this author Originally published26 May 2017https://doi.org/10.1161/RES.0000000000000156Circulation Research. 2017;120:1687Therapeutic Potential of Synthetic Stem Cells (p 1768)Download figureDownload PowerPointLuo et al generate synthetic stem cells for cardiac therapies.Evidence indicates that the administration of stem cells, such as mesenchymal stem cells (MSCs), to patients with damaged hearts can improve myocardial function. It is currently believed that such reparative effects of MSCs are largely due to secreted factors. However, treating patients directly with such factors has been unsuccessful—possibly because the effects of the factors could not be sustained. Luo and colleagues reasoned that if such factors were enclosed in protective packaging, they might prove more effective. To find out, the team loaded MSC secretome proteins onto particles of poly(lactic-co-glycolic acid)—a biocompatible polymer that protects cytokines from degradation—and coated these particles with MSC membranes. Like regular MSCs, the repackaged synthetic MSCs (synMSCs), when cocultured with neonatal rat cardiac myocytes, synMSCs induced proliferation and contractility. And when given to mice with myocardial infarction, the reduced infarct size increased ventricle wall thickness and increased blood vessel density. Given these similar results, unpackaging and repackaging MSCs may seem unnecessary, but the defined composition of the synMSCs should provide a more uniform and predictable medication than cell-based approaches. Furthermore, the synMSCs exhibited superior stability to MSCs—suggesting synMSCs may be useful as an off-the-shelf treatment option.20-HETE–GPR75 Pairing and Hypertension (p 1776)Download figureDownload PowerPointGarcia et al identify a receptor for the potent inducer of hypertension 20-HETE.Hypertension is the leading cause of stroke and cardiovascular diseases, but because many different environmental and genetic factors contribute to the disorder, the underlying pathology is difficult to define. The complex etiology of hypertension could explain why, despite a range of treatment options, many patients have uncontrolled blood pressure (resistant hypertension). Among several hypertension-inducing factors is 20-hydroxyeicosatetraenoic acid (20-HETE)—a lipid produced by arachidonic acid hydrolysis. 20-HETE promotes vascular dysfunction—including inflammation and remodeling—and elevated blood levels of 20-HETE have been linked with hypertension, stroke, myocardial infarction, and vascular disease. To shed light on the mode of action of 20-HETE, Garcia and colleagues have now identified a 20-HETE receptor on endothelial and smooth muscle cells called G-protein receptor 75 (GPR75), which associates with G-protein–coupled receptor kinase interactor 1 (GIT1). The team showed that both GPR75 and GIT1 are required for 20-HETE-induced signaling activity. Moreover, genetic knockdown of GPR75 in mice prevented 20-HETE-dependent vascular dysfunction and hypertension. These findings open potential new avenues for developing treatments for resistant hypertension.Monocyte Patrolling in Arteries (p 1789)Download figureDownload PowerPointQuintar et al investigate monocyte patrolling behavior in arteries.Unlike classical inflammatory monocytes, nonclassical monocytes patrol blood vessel endothelium scavenging dead cells and debris. These patrolling cells were discovered in the microcirculation, and all subsequent studies have focused on these vessels. As a result, with the exception of monocyte recruitment to atherosclerotic plaques in arteries, little is known about monocyte-endothelial interactions in large vessels. Using a recently developed imaging technology, called intravital live cell triggered imaging system (ILTIS), Quintar and colleagues have now been able to monitor nonclassical monocytes in the arteries of healthy, hyperlipidemic, and atherosclerotic mice. They found that monocytes patrol healthy arteries—with each patrolling session lasting 5 to 10 minutes. In 2 different mouse models of hyperlipidemia, the patrolling behavior of these cells was increased by 8- to 9-fold. In atherogenic mice, patrolling increased by 22-fold, with each patrol lasting longer and proceeding more slowly. The number of patrolling cells directly correlated with the extent of endothelial damage, and mice with deficient patrolling monocytes exhibited greater atherosclerotic lesions. Together, the results suggest that the patrolling cells have a protective role in arteries and raise the possibility that therapeutically increasing monocyte patrolling behavior could help in reducing atherogenesis. Previous Back to top Next FiguresReferencesRelatedDetails May 26, 2017Vol 120, Issue 11 Advertisement Article InformationMetrics © 2017 American Heart Association, Inc.https://doi.org/10.1161/RES.0000000000000156 Originally publishedMay 26, 2017 PDF download Advertisement

20-HETE Signals Through G-Protein-Coupled Receptor GPR75 (Gq) to Affect Vascular Function and Trigger Hypertension.

20-Hydroxyeicosatetraenoic acid (20-HETE), one of the principle cytochrome P450 eicosanoids, is a potent vasoactive lipid whose vascular effects include stimulation of smooth muscle contractility, migration, and proliferation, as well as endothelial cell dysfunction and inflammation. Increased levels of 20-HETE in experimental animals and in humans are associated with hypertension, stroke, myocardial infarction, and vascular diseases. To date, a receptor/binding site for 20-HETE has been implicated based on the use of specific agonists and antagonists. The present study was undertaken to identify a receptor to which 20-HETE binds and through which it activates a signaling cascade that culminates in many of the functional outcomes attributed to 20-HETE in vitro and in vivo. Using crosslinking analogs, click chemistry, binding assays, and functional assays, we identified G-protein receptor 75 (GPR75), currently an orphan G-protein-coupled receptor (GPCR), as a specific target of 20-HETE. In cultured human endothelial cells, 20-HETE binding to GPR75 stimulated Gαq/11 protein dissociation and increased inositol phosphate accumulation and GPCR-kinase interacting protein-1-GPR75 binding, which further facilitated the c-Src-mediated transactivation of epidermal growth factor receptor. This results in downstream signaling pathways that induce angiotensin-converting enzyme expression and endothelial dysfunction. Knockdown of GPR75 or GPCR-kinase interacting protein-1 prevented 20-HETE-mediated endothelial growth factor receptor phosphorylation and angiotensin-converting enzyme induction. In vascular smooth muscle cells, GPR75-20-HETE pairing is associated with Gαq/11- and GPCR-kinase interacting protein-1-mediated protein kinase C-stimulated phosphorylation of MaxiKβ, linking GPR75 activation to 20-HETE-mediated vasoconstriction. GPR75 knockdown in a mouse model of 20-HETE-dependent hypertension prevented blood pressure elevation and 20-HETE-mediated increases in angiotensin-converting enzyme expression, endothelial dysfunction, smooth muscle contractility, and vascular remodeling. This is the first report to identify a GPCR target for an eicosanoid of this class. The discovery of 20-HETE-GPR75 pairing presented here provides the molecular basis for the signaling and pathophysiological functions mediated by 20-HETE in hypertension and cardiovascular diseases.

Upregulation of 20-HETE Synthetic Cytochrome P450 Isoforms by Oxygen-Glucose Deprivation in Cortical Neurons.

20-Hydroxyeicosatetraenoic acid (20-HETE), a potent vasoconstrictor, is a cytochrome P450 (CYP) 4A/4F-derived metabolite of arachidonic acid. Inhibition of 20-HETE synthesis protects brain from ischemic injury. However, that protection is not associated with changes in cerebral blood flow. The present study examined whether CYP4A isoforms are expressed in neurons, whether they produce 20-HETE in neurons, and whether neuronally derived 20-HETE exerts direct neurotoxicity after oxygen-glucose deprivation (OGD). The expression of Cyp4a10 and Cyp4a12a mRNA in cultured mouse cortical neurons increased significantly at 1 and 3h after exposure to 1h of OGD. Reoxygenation also markedly augmented the expression of CYP4A protein in neurons and increased 20-HETE levels in the culture medium. Cell viability after OGD increased after treatment with a 20-HETE synthesis inhibitor or an antagonist. That effect was reversed by co-administration of a 20-HETE agonist. These results indicate that neurons express Cyp4a10 and 4a12a, that expression of these isoforms is upregulated by OGD stress, and that neuronally derived 20-HETE directly contributes to neuronal death after reoxygenation.

Elevated 20-HETE impairs coronary collateral growth in metabolic syndrome via endothelial dysfunction.

Coronary collateral growth (CCG) is impaired in metabolic syndrome (MetS). microRNA-145 (miR-145-Adv) delivery to our rat model of MetS (JCR) completely restored and neutrophil depletion significantly improved CCG. We determined whether low endogenous levels of miR-145 in MetS allowed for elevated production of 20-hydroxyeicosatetraenoic acid (20-HETE), which, in turn, resulted in excessive neutrophil accumulation and endothelial dysfunction leading to impaired CCG. Rats underwent 0-9 days of repetitive ischemia (RI). RI-induced cardiac CYP4F (neutrophil-specific 20-HETE synthase) expression and 20-HETE levels were increased (4-fold) in JCR vs. normal rats. miR-145-Adv and 20-HETE antagonists abolished and neutrophil depletion (blocking antibodies) reduced (~60%) RI-induced increases in CYP4F expression and 20-HETE production in JCR rats. Impaired CCG in JCR rats (collateral-dependent blood flow using microspheres) was completely restored by 20-HETE antagonists [collateral-dependent zone (CZ)/normal zone (NZ) flow ratio was 0.76 ± 0.07 in JCR + 20-SOLA, 0.84 ± 0.05 in JCR + 20-HEDGE vs. 0.11 ± 0.02 in JCR vs. 0.84 ± 0.03 in normal rats]. In JCR rats, elevated 20-HETE was associated with excessive expression of endothelial adhesion molecules and neutrophil infiltration, which were reversed by miR-145-Adv. Endothelium-dependent vasodilation of coronary arteries, endothelial nitric oxide synthase (eNOS) Ser1179 phosphorylation, eNOS-dependent NO·- production and endothelial cell survival were compromised in JCR rats. These parameters of endothelial dysfunction were completely reversed by 20-HETE antagonism or miR-145-Adv delivery, whereas neutrophil depletion resulted in partial reversal (~70%). We conclude that low miR-145 in MetS allows for increased 20-HETE, mainly from neutrophils, which compromises endothelial cell survival and function leading to impaired CCG. 20-HETE antagonists could provide viable therapy for restoration of CCG in MetS.NEW & NOTEWORTHY Elevated 20-hydroxyeicosatetraenoic acid (20-HETE) impairs coronary collateral growth (CCG) in metabolic syndrome by eliciting endothelial dysfunction and apoptosis via excessive neutrophil infiltration. 20-HETE antagonists completely restore coronary collateral growth in metabolic syndrome. microRNA-145 (miR-145) is an upstream regulator of 20-HETE production in metabolic syndrome; low expression of miR-145 in metabolic syndrome promotes elevated production of 20-HETE.

CYP Genetic Variants, CYP Metabolite Levels, and Neurologic Deterioration in Acute Ischemic Stroke in Chinese Population

The mechanisms of neurologic deterioration (ND) are not fully understood. The aim of the present study was to evaluate the relationship between CYP genetic variants and CYP metabolite levels with ND in acute ischemic stroke patients. Eleven single nucleotide polymorphisms (SNPs) of seven CYP genes were genotyped in 396 patients with acute ischemic stroke. The CYP plasma metabolite levels (20-hydroxyeicosatetraenoic acid [HETE], total epoxyeicosatrienoic acids [EETs], and dihydroxyeicosatrienoic acids [DiHETEs]) were also assessed. The primary outcome was ND within 10 days on admission. ND was defined as an increase of two or more points in the National Institutes of Health Stroke Scale score. Among 396 patients, 101 patients (25.5%) experienced ND. The plasma levels of 20-HETE and DiHETEs were significantly higher and the EET levels were significantly lower in patients with ND compared to patients without ND. Univariate analyses revealed that old age, diabetes mellitus (DM), higher fasting glucose, and higher hemoglobin A1c (HbA1c) were associated with ND. CYP2C8 rs17110453 CC, EPHX2 rs751141 GG, and CYP4A11 rs9333025 GG were independently associated with ND after adjusting age, DM, fasting glucose, and HbA1c (odds ratio [OR]: 1.60, 95% confidence interval [CI]: 1.02-3.72; OR: 3.01, 95% CI: 1.29-7.13; OR: 2.75, 95% CI: 1.17-6.24, respectively). Also, these polymorphisms were associated with CYP metabolite levels in patients with ND. ND is fairly common in acute ischemic stroke. Specific CYP gene SNPs are associated with CYP plasma metabolite levels, which may explain their associations with ND. Further studies are needed to validate our findings.

20-Hydroxyeicosatetraenoic Acid as a Predictor of Neurological Deterioration in Acute Minor Ischemic Stroke.

The relationship between high plasma 20-hydroxyeicosatetraenoic acid (20-HETE) levels and neurological deterioration (ND) has not been investigated in patients with acute minor ischemic stroke. We conducted a prospective, multicenter observational study in patients with acute minor ischemic stroke. Plasma levels of 20-HETE were measured at admission in all patients. The primary end point of the study was ND within 10 days after admission. The degree of disability was assessed using modified Rankin scale at 3 months after admission. A total of 322 patients were enrolled, of which 85 patients (26.4%) developed ND. Mean 20-HETE level was 1687±158 pmol/L. On multivariate analyses, high level (>1675 pmol/L) of 20-HETE was an independent predictor of ND (third and fourth quartiles). Neurological deterioration was associated with a higher risk of poor outcome (modified Rankin scale scores 3-6) at 3 months. ND is fairly common in acute minor ischemic stroke and is associated with poor prognosis. Elevated plasma level of 20-HETE may be a predictor for ND in acute minor ischemic stroke.

Abstract P186: Proximal Tubular-Specific Overexpression of the Cyp4a12-20-Hete Synthase Promotes Hypertension

20-Hydroxyeicosatetraenoic acid (20-HETE) is a cytochrome P450 (CYP)-derived arachidonic acid metabolite linked to regulation of blood pressure via actions on the renal microvasculature and tubules. In renal microvessels, 20-HETE promotes vasoconstriction, vascular remodeling, and vascular injury; all of which contribute to hypertension, whereas in tubular structures 20-HETE has been linked to inhibition of sodium transport and lowering of blood pressure. Induction or global overexpression of Cyp4a12-20-HETE synthase, the primary 20-HETE producing enzyme in mice, results in hypertension. Since these mice display global overproduction of 20-HETE, it is difficult to dissect the exact contribution of vascular versus tubular 20-HETE to the hypertension. To begin addressing this issue, the current study was undertaken to define the blood pressure phenotype of novel transgenic mice with proximal tubule-specific overexpression of the Cyp4a12-20-HETE synthase (PEPCK-cyp4a12 mice). These mice generated by crossing the Cyp4a12 fl/fl with PEPCK (phosphoenolpyruvate carboxykinase promoter)-Cre mice, showed increased Cyp4a12 mRNA expression (2.6±0.9 fold increase; p&lt;0.05) and 20-HETE production in the renal cortex (138±32 pg/mg vs. 80±6 pg/mg). Most importantly, the systolic blood pressure was markedly elevated in the PEPCK-Cyp4a12 mice as compared to WT littermates (142±2 vs. 111±3 mmHg; p&lt;0.05). Interestingly, the PEPCK-Cyp4a12 mice exhibited significantly higher levels of urinary 20-HETE as compared to WT littermates (205±50 vs 83±5 pg/ml; p&lt;0.05) whereas plasma 20-HETE levels remained unchanged (231±32 vs 190±25 pg/ml). Moreover, in PEPCK-Cyp4a12 (n=4) urinary volume was lower (2.15±0.05 vs 3.17±0.20 ml/day, p=0.003) and UNaV appeared lower (181±7 vs 194±25 μmol/day, p=0.35) as compared to WT littermates. These results are in line with the possibility that 20-HETE overproduction at the level of the proximal tubule promotes rather than opposes hypertension. The exact mechanisms need to be further examined.

Abstract P221: Vascular Smooth Muscle-Specific Overexpression of Cyp4a12-20-HETE Synthase Causes Hypertension and Vascular Remodeling

20-Hydroxyeicosatetraenoic acid (20-HETE) is a potent vasoactive eicosanoid of the microcirculation exhibiting effects on vascular smooth muscle (VSM) function that include stimulation of contractility, migration and growth. We have previously demonstrated in mice which globally overexpress 20-HETE that hypertension as well as vascular remodeling is not fully prevented by pharmacological normalization of blood pressure. However, both hypertension and vascular remodeling are prevented by antagonism of 20-HETE, suggesting that 20-HETE exerts vascular effects independent of hypertension. To examine the contribution of VSM-derived 20-HETE to hypertension and vascular remodeling, we have developed a transgenic mouse model that overexpresses the primary mouse 20-HETE synthase, Cyp4a12, specifically in VSM by crossbreeding floxed Cyp4a12 with Myh11-Cre mice. All mice carry the floxed Cyp4a12 gene and express a GFP protein under control of a modified CMV promoter. Cre-recombination excises the GFP cDNA and inserts the Cyp4a12 cDNA. Three to four month old male Cyp4a12-floxed mice carrying the Myh11-Cre gene (Cyp4a12 fl/fl Myh11 Cre+/- ) exhibited higher systolic blood pressure than control mice Cyp4a12 fl/fl Myh11 Cr-/- (WT) mice (135 vs. 115 mmHg, n=4, *p&lt;0.05). 20-HETE production in Cyp4a12 fl/fl Myh11 Cre+/- mice were higher than in WT in mesenteric (3333±891 vs. 545± 196 ng/mg/h) and renal interlobar arteries (RIA; 1859±376 vs. 242±62 ng/mg/h). Plasma levels of 20-HETE were also elevated (324±61 vs. 185±34 pg/mL) while urinary levels were not significantly different (146±26 vs. 117±29 pg/mL). We also observed increased medial thickness and decreased lumen area of blood vessels by Myh11 immunofluorescence in heart and kidney sections. RIA from male Myh11-Cyp4a12 mice displayed higher constrictor sensitivity to phenylephrine and impaired relaxation to acetylcholine compared to WT. Taken together, these data suggest that this model displays hypertension and pathological hypertrophic vascular remodeling. We therefore conclude that the Cyp4a12 fl/fl Myh11 Cre/- is a promising and unique transgenic mouse model to examine the contribution of smooth muscle-derived 20-HETE to hypertension and hypertrophic vascular remodeling.