Comprehensive metabonomic analysis of heart tissue from isoproterenol-induced myocardial infarction rat based on reversed-phase and hydrophilic interaction chromatography coupled to mass spectrometry

Involvement of GAT2/Slc6a13 in hypotaurine uptake at fetal-facing plasma membrane of syncytiotrophoblasts at mid-to-late gestation in rats and mice

INTRODUCTION

Hypotaurine, a precursor to taurine, is known for its antioxidant properties and is prominently present in fetal plasma and the placenta. Our previous research revealed that ezrin-knockout mice experience fetal growth retardation, coinciding with reduced hypotaurine levels in fetal plasma. This study aims to elucidate the expression and role of hypotaurine transporters within the placenta.

METHODS

We employed quantitative RT-PCR to measure mRNA expression of GAT transporter family members in the placenta during mid-to-late gestation. LC/MS/MS was used to analyze the distribution of hypotaurine in different placental subregions. Immunohistochemistry was utilized to examine the localization of GAT2 in mice. Placental hypotaurine uptake from fetal circulation was studied via umbilical perfusion in rats.

RESULTS

Among hypotaurine transporters, GAT2 exhibited increased mRNA and protein expression in murine placenta during mid-to-late gestation. Notably, GAT2/Slc6a13 mRNA and hypotaurine were most concentrated in the labyrinth of murine placenta. In contrast, enzymes responsible for hypotaurine synthesis, such as cysteine dioxygenase, cysteine sulfinic acid decarboxylase, and 2-aminoethanethiol dioxygenase, showed minimal expression in the labyrinth. These findings suggest that GAT2 is a key determinant of hypotaurine levels in the placental labyrinth. Immunohistochemical examination unveiled that GAT2 was predominantly localized on the fetal-facing plasma membrane within syncytiotrophoblasts, which co-localized with ezrin. In rat umbilical perfusion experiments, the GAT2/3 and TauT inhibitor, SNAP-5114, significantly reduced hypotaurine extraction from fetal circulation to the placenta.

DISCUSSION

The results suggest that GAT2 plays a pivotal role in the concentrative uptake of hypotaurine from fetal plasma within syncytiotrophoblasts of the placenta.

Cardioprotective and hypotensive mechanistic insights of hydroethanolic extract of Cucumis melo L. kernels in isoprenaline-induced cardiotoxicity based on metabolomics and in silico electrophysiological models

Background: Cardiovascular diseases (CVD) continue to threaten health worldwide, and account for a significant portion of deaths and illnesses. In both developing and industrialized nations, they challenge their health systems. There are several traditional uses of Cucurbitaceae seeds in Pakistan, India, Iran, and China, including treating cardiovascular, neurological, and urogenital diseases. Methods: In the present work, integrated techniques of metabolomics profiling and computational cardiomyocyte stimulation were used to investigate possible mechanisms of C. melo in isoprenaline (ISO)-induced myocardial infarction. In vitro, vasoconstrictions, paired atria, and in vivo invasive blood pressure measurement models were performed to explore the mechanism of action of C. melo hydroethanolic seed extract (Cm-EtOH). Results: Results showed that Cm-EtOH demonstrates NO-based endothelium-derived relaxing factor (EDRF) vasorelaxant response, negative chronotropic and inotropic response in the atrium, and hypotensive effects in normotensive rats. Results also revealed that Cm-EtOH decreases cardiomyocyte hypertrophy and reverts the altered gene expressions, biochemical, and metabolites in ISO-induced myocardial infarction (MI) rats. The extract additionally reversed ISO-induced MI-induced oxidative stress, energy consumption, and amino acid metabolism. Moreover, C. melo seeds increased EDRF function, energy production, and antioxidant capacity to treat myocardial and vascular disorders. In computational cardiomyocyte simulation, gallic acid reduced action potential duration, upstroke velocity (dV/dtmax), and effective refractory period. Conclusion: This study highlights the therapeutic potential of C. melo seeds to treat cardiovascular diseases and provides mechanistic insight into its antihypertensive and cardioprotective activities.

Integration of metabolomics and network pharmacology to reveal the protective mechanism underlying Wogonoside in acute myocardial ischemia rats

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional medicine, both Scutellaria baicalensis Georgi (SBG) and the traditional formulas composed of it have been used to treat a wide range of diseases, including cancer and cardiovascular. Wogonoside (Wog) is the biologically active flavonoid compound extracted from the root of SBG, with potential cardiovascular protective effects. However, the mechanisms underlying the protective effect of Wog on acute myocardial ischemia (AMI) have not yet been clearly elucidated.

AIM OF THE STUDY

To explore the protective mechanism of Wog on AMI rats by comprehensively integrating traditional pharmacodynamics, metabolomics, and network pharmacology.

METHODS

The rat was pretreatment with Wog at a dose of 20 mg/kg/d and 40 mg/kg/d once daily for 10 days and then ligated the left anterior descending coronary artery of rats to establish the AMI rat model. Electrocardiogram (ECG), cardiac enzyme levels, heart weight index (HWI), Triphenyltetrazolium chloride (TTC) staining, and histopathological analyses were adopted to evaluate the protective effect of Wog on AMI rats. Moreover, a serum metabolomic-based UHPLC-Q-Orbitrap MS approach was performed to find metabolic biomarkers and metabolic pathways, and network pharmacology analysis was applied to predict targets and pathways of Wog in treating AMI. Then, the network pharmacology and metabolomic results were integrated to elucidate the mechanism of Wog in treating AMI. Finally, RT- PCR was used to detect the mRNA expression levels of PTGS1, PTGS2, ALOX5, and ALOX15 to validate the result of integrated metabolomics and network analysis.

RESULTS

Pharmacodynamic studies suggest that Wog could effectively prevent the ST-segment of electrocardiogram elevation, reduce the myocardial infarct size, heart weight index, and cardiac enzyme levels, and alleviate cardiac histological damage in AMI rats. Metabolomics analysis showed that the disturbances of metabolic profile in AMI rats were partly corrected by Wog and the cardio-protection effects on AMI rats involved 32 differential metabolic biomarkers and 4 metabolic pathways. In addition, the integrated analysis of network pharmacology and metabolomics showed that 7 metabolic biomarkers, 6 targets, and 6 crucial pathways were the main mechanism for the therapeutic application of Wog for AMI. Moreover, the results of RT-PCR showed that PTGS1, PTGS2, ALOX5, and ALOX15 mRNA expression levels were reduced after treatment with Wog.

CONCLUSION

Wog exerts cardio-protection effects on AMI rats via the regulation of multiple metabolic biomarkers, multiple targets, and multiple pathways, our current study will provide strong scientific evidence supporting the therapeutic application of Wog for AMI.

Modified Taohong Siwu decoction improves cardiac function after myocardial ischaemia and reperfusion in rats by promoting endogenous stem cell mobilization and regulating metabolites

CONTEXT

Taohong Siwu decoction (THSWD) has been shown to promote heart repair in myocardial infarction.

OBJECTIVE

To determine the effects of modified THSWD (THSWD plus four ingredients) on myocardial ischaemia and reperfusion (I/R) injury.

MATERIALS AND METHODS

Sixty Sprague-Dawley rats were randomly divided into the I/R group and three different modified THSWD dose groups (gavage administration, 1.215, 2.43, and 4.86 g, respectively). 2,3,5-Triphenyltetrazolium chloride and Evans blue staining were used to detect the infarct area at 24 h after treatment. The serum biochemical indexes and cell apoptosis were examined to determine myocardial injury. The number of endogenous stem cells, expression of stromal dell derived factor-1 (SDF-1) and stem cell factor (SCF), and cardiac function were measured at 4 weeks. The serum was collected for metabolomic analysis.

RESULTS

The high-dose modified THSWD group presented a reduced infarction area (decreased by 21.3%), decreased levels of lactate dehydrogenase and creatinine kinase, attenuated cell apoptosis, and enhanced superoxide dismutase activity in early stage I/R compared with other groups. The serum SCF and SDF-1 levels were higher in the high-dose group than in the I/R group. At 4 weeks, the infarct size and collagen content were the lowest, and the ejection fraction and fractional shortening values were the highest in the high-dose group. Moreover, high-dose modified THSWD affected the metabolism of phosphonate and phosphonate, taurine, and hypotaurine.

CONCLUSIONS

Endogenous stem cell mobilization and metabolic regulation were related to the cardioprotection of modified THSWD. We provided a new strategy and direction for the treatment of cardiovascular diseases with traditional Chinese medicine.

Impact of a long-term high-fructose diet on systemic metabolic profiles of mice

Evidence is mounting that chronic high-fructose diets (HFrD) can lead to metabolic abnormalities and cause a variety of diseases. However, the underlying mechanism by which long-term high fructose intake influencing systemic metabolism remains unclarified. This study, therefore, attempted to investigate the impact of a high-fructose diet on metabolic profile. Four-week-old male C57BL/6 mice were fed with 15% fructose solution as their only source of water for 8 weeks. Afterward, gas chromatography-mass spectrometry (GC-MS) was employed to investigate the comprehensive metabolic profile of serum, muscle, liver, heart, white adipose, brain, and kidney tissues, and multivariate analyses including principal component analysis (PCA) and orthogonal partial least squared-discriminant analysis (OPLS-DA) were applied to screen for differential metabolite expression between the HFrD and control groups. Furthermore, the MetaboAnalyst 5.0 (http://www.metaboanalyst.ca) and Kyoto Encyclopedia of Genes and Genomes database (KEGG; http://www.kegg.jp) were employed to portray a detailed metabolic network. This study identified 62 metabolites related to HFrD and 10 disturbed metabolic pathways. The results indicated that high fructose intake mainly influenced amino acid metabolism and biosynthesis (glycine, serine, and threonine metabolism; aspartate, and glutamate metabolism; phenylalanine, tyrosine, and tryptophan biosynthesis, and arginine biosynthesis pathways), glutathione metabolism, sphingolipid metabolism, and glyoxylate and dicarboxylate metabolism in serum, whereas these pathways were suppressed in the brain. Starch and sucrose metabolism in muscle was also disrupted. These results elucidate the effects of long-term high fructose consumption on the metabolic profiles of various tissues and provide new insight for the identification of potential metabolic biomarkers and pathways disrupted by high fructose.

Untargeted Metabolomics Studies of H9c2 Cardiac Cells Submitted to Oxidative Stress, β-Adrenergic Stimulation and Doxorubicin Treatment: Investigation of Cardiac Biomarkers

One of the biggest challenges in the search for more effective treatments for diseases is understanding their etiology. Cardiovascular diseases (CVD) are an important example of this, given the high number of deaths annually. Oxidative stress (the imbalance between oxidant and antioxidant species in biological system) is one of the factors responsible for CVD occurrence, demanding extensive investigation. Excess of reactive oxygen species (ROS) are primarily responsible for this condition, and clinical and scientific literature have reported a significant increase in ROS when therapeutic drugs, such as doxorubicin and isoproterenol, are administered. In this context, the aim of this study is the investigation of potential biomarkers that might be associated with oxidative stress in cardiomyocytes. For this purpose, H9c2 cardiomyocytes were submitted to oxidative stress conditions by treatment with doxorubicin (DOX), isoproterenol (ISO) and hydrogen peroxide (PER). Metabolomics analyses of the cell extract and the supernatant obtained from the culture medium were then evaluated by CE-ESI(+)-TOF-MS. Following signal processing, statistical analyses, and molecular features annotations, the results indicate changes in the aspartate, serine, pantothenic acid, glycerophosphocholine and glutathione metabolism in the cell extract.

Metabolomics based mechanistic insights to vasorelaxant and cardioprotective effect of ethanolic extract of Citrullus lanatus (Thunb.) Matsum. & Nakai. seeds in isoproterenol induced myocardial infraction

BACKGROUND

Cardiovascular diseases (CVDs) are a significant cause of morbidity and death in the current world, posing a challenge to both developing and industrialized nation's health systems. Citrullus lanatus (Thunb.) Matsum. & Nakai. seeds have long been utilized to supplement and enhance health and treat cardiovascular illnesses. However, its treatments for CVDs are still unknown. More research is required to fully comprehend the impact of C. lanatus seeds on vasorelaxation and myocardial infractions.

PURPOSE

Therefore, an integrated metabolomics profiling technique was used to investigate possible pathways of C. lanatus in isoproterenol (ISO)-induced myocardial infarction (MI). Isoproterenol causes long-term cardiac hypertrophy by causing cardiomyocyte compensatory loss, eventually leading to heart failure.

METHODS

In vitro models of vasoconstriction, atrium, and in vivo models of invasive blood pressure measurement and isoproterenol (ISO) induced cardiac hypertrophy in rats were used to understand underlying mechanistic by LC-MS/MS based dynamic metabolomics analysis of the serum and heart samples to be investigated the effect of ethanolic extract of C. lanatus (Cl.EtOH).

RESULTS

Cl.EtOH exhibited vasorelaxant, negative chronotropic, and inotropic effects in in-vitro models whereas, a potent hypotensive effect was observed in normotensive rats. The Cl.EtOH protected the animals from ISO-induced myocardial infarction (MI) with therapeutic interventions in left ventricular thickness, cardiomyocyte hypertrophy, mRNA gene expression, biochemical assays, and metabolomic profiling of serum and heart tissues.

CONCLUSIONS

For the first time, our study confirmed that C. lanatus seeds (Cl.EtOH) possess significant antihypertensive and prevent ISO-induced myocardial infarction. These findings comprehensively demonstrated mechanistic insights of Cl.EtOH in vasorelaxation and myocardial infarction. The current study provides evidence for further mechanistic studies and the development of C. lanatus seeds as a potential therapeutic intervention for patients with cardiovascular disorders.

Metabolomics analysis delineates the therapeutic effects of hydroethanolic extract of Cucumis sativus L. seeds on hypertension and isoproterenol-induced myocardial infarction

Cucumis sativus L., widely cultivated as an edible vegetable. Its seeds are well reputed for cardiovascular preventive properties. However, the mechanisms underlying for cardiovascular protection of C. sativus are still unidentified. Therefore, this study utilized a metabolomics approach to investigate putative mechanisms of C. sativus seeds in myocardial infarction (MI) and in vitro models of vasoconstriction, atrium, and invasive blood pressure measurement. Results showed that Cu.EtOH extract showed a vasorelaxant response with potent hypotensive effect in normotensive rats and L-NAME induced hypertension. Cu.EtOH caused a negative inotropic and positive chronotropic effect on the atrium. Cu.EtOH protected the animals from ISO-induced myocardial infarction (MI) interventions in left ventricular thickness, cardiomyocyte hypertrophy, mRNA gene expression, and biochemical assays. The metabolomics data suggested that Cu.EtOH mainly affected amino acid metabolism, BCAA degradation, ketone bodies degradation, and oxidative stress. Our study showed that Cu.EtOH suppressed inflammation with a strong anti-myocardial infarction impact. Additionally, our findings indicated Cu.EtOH reverted the amino acid metabolism, BCAA, and ketone bodies degradation. The findings show the antihypertensive mechanism of Cu.EtOH may include the modulation of endothelium-derived relaxing factor (EDRF) produced from nitric oxide (NO) and is connected with vascular endothelial function. C. sativus seeds, in particular, played a pivotal role in the treatment of myocardial and vascular disorders by enhancing the EDRF mechanism, energy generation, and antioxidant capacity. In summary, our findings showed the mechanistic insights on the therapeutic potential of C. sativus seeds for cardiovascular disorders.

Comprehensive analysis of metabolic changes in rats exposed to acrylamide

Acrylamide (ACR) is a widely used environmentally hazardous compound that is known to be neurotoxic, genotoxic, carcinogenic, and reproductive toxicity. It is widely present in soil, water, agents used in chemical industries, and food. It can be distributed to all organs and tissues, and can cause damage to various human systems and those of other animals. Previous metabolomics studies have mainly focused on metabolites in serum and urine, but have lacked comprehensive analysis of major organs and tissues. In the current study, a gas chromatography-massspectrometry method was used to investigate mechanisms underlying organ toxicity, in an effort to identify potentially sensitive biomarkers in the main target tissues of rats after ACR exposure. Male Sprague-Dawley rats were assigned to two groups; a control group and a group treated with 20 mg kg^-1 ACR intragastrically for 6 weeks. Metabolite changes in the two groups were statistically analyzed. The respective numbers of altered metabolites in the hippocampus, cortex, kidney, serum, heart, liver, and kidney fat were 21, 21, 17, 5, 15, 14, and 6. There were 14 metabolic pathways related to amino acid, fatty acid, purine, and energy metabolism, revealing that the toxic mechanism of ACR may involve oxidative stress, inflammation, and amino acid metabolism and energy disorders.

Dihydrosphingosine driven enrichment of sphingolipids attenuates TGFβ induced collagen synthesis in cardiac fibroblasts

The sphingolipid de novo synthesis pathway, encompassing the sphingolipids, the enzymes and the cell membrane receptors, are being investigated for their role in diseases and as potential therapeutic targets. The intermediate sphingolipids such as dihydrosphingosine (dhSph) and sphingosine (Sph) have not been investigated due to them being thought of as precursors to other more active lipids such as ceramide (Cer) and sphingosine 1 phosphate (S1P). Here we investigated their effects in terms of collagen synthesis in primary rat neonatal cardiac fibroblasts (NCFs). Our results in NCFs showed that both dhSph and Sph did not induce collagen synthesis, whilst dhSph reduced collagen synthesis induced by transforming growth factor β (TGFβ). The mechanisms of these inhibitory effects were associated with the increased activation of the de novo synthesis pathway that led to increased dihydrosphingosine 1 phosphate (dhS1P). Subsequently, through a negative feedback mechanism that may involve substrate-enzyme receptor interactions, S1P receptor 1 expression (S1PR1) was reduced.

Sphingolipid Signature of Human Feto-Placental Vasculature in Preeclampsia

Bioactive sphingolipids are emerging as key regulators of vascular function and homeostasis. While most of the clinical studies have been devoted to profile circulating sphingolipids in maternal plasma, little is known about the role of the sphingolipid at the feto-placental vasculature, which is in direct contact with the offspring circulation. Our study aims to compare the sphingolipid profile of normal with preeclamptic (PE) placental chorionic arteries and isolated endothelial cells, with the goal of unveiling potential underlying pathomechanisms in the vasculature. Dihydrosphingosine and sphingomyelin (SM) concentrations (C16:0-, C18:0-, and C24:0- sphingomyelin) were significantly increased in chorionic arteries of preeclamptic placentas, whereas total ceramide, although showing a downward trend, were not statistically different. Moreover, RNA and immunofluorescence analysis showed impaired sphingosine-1-phosphate (S1P) synthesis and signaling in PE vessels. Our data reveal that the exposure to a deranged maternal intrauterine environment during PE alters the sphingolipid signature and gene expression on the fetal side of the placental vasculature. This pathological remodeling consists in increased serine palmitoyltransferase (SPT) activity and SM accrual in PE chorionic arteries, with concomitance impairment endothelial S1P signaling in the endothelium of these vessels. The increase of endothelial S1P phosphatase, lyase and S1PR2, and blunted S1PR1 expression support the onset of the pathological phenotype in chorionic arteries.

A wide-targeted urinary and serum metabolomics strategy reveals the effective substance of the Wu-tou decoction

As an important Chinese medicine decoction, Wu-tou decoction has been used to treat rheumatic arthritis for more than a thousand years. We previously reported that the Wu-tou decoction could change the urinary and serum metabolites in adjuvant-induced arthritis rats significantly. The purpose of this research was to confirm the potential biomarkers obtained by previous non-targeted metabolomics study through quantitative analysis by liqui chromatography with tandem mass spectrometry, in the meantime, to further study the effective material basis of Wu-tou decoction. Firstly, the important compounds in the tryptophan metabolism pathway, the arginine and proline metabolism pathway, the amino acid metabolism pathway, the tricarboxylic acid cycle, the vitamin B₆ metabolism pathway, and the phenylalanine metabolism pathway, which were identified as potential biomarkers in previous study, were selected for quantitative analysis. Then the linearity, limit of detection, limit of quantification, selectivity, accuracy, precision, stability, recovery, and matrix effect of the quantitative method were examined. Finally, ten and eighteen metabolites were quantitatively analyzed in the serum and urine, respectively. The results showed that seven out of ten serum potential biomarkers and ten out of eighteen urine potential biomarkers were confirmed as real biomarkers. This research provides a powerful reference for the study on effective material basis of Wu-tou decoction.

The role of dihydrosphingolipids in disease

Dihydrosphingolipids refer to sphingolipids early in the biosynthetic pathway that do not contain a C4-trans-double bond in the sphingoid backbone: 3-ketosphinganine (3-ketoSph), dihydrosphingosine (dhSph), dihydrosphingosine-1-phosphate (dhS1P) and dihydroceramide (dhCer). Recent advances in research related to sphingolipid biochemistry have shed light on the importance of sphingolipids in terms of cellular signalling in health and disease. However, dihydrosphingolipids have received less attention and research is lacking especially in terms of their molecular mechanisms of action. This is despite studies implicating them in the pathophysiology of disease, for example dhCer in predicting type 2 diabetes in obese individuals, dhS1P in cardiovascular diseases and dhSph in hepato-renal toxicity. This review gives a comprehensive summary of research in the last 10-15 years on the dihydrosphingolipids, 3-ketoSph, dhSph, dhS1P and dhCer, and their relevant roles in different diseases. It also highlights gaps in research that could be of future interest.

Development of a rapid profiling method for the analysis of polar analytes in urine using HILIC-MS and ion mobility enabled HILIC-MS

INTRODUCTION

As large scale metabolic phenotyping is increasingly employed in preclinical studies and in the investigation of human health and disease the current LC-MS/MS profiling methodologies adopted for large sample sets can result in lengthy analysis times, putting strain on available resources. As a result of these pressures rapid methods of untargeted analysis may have value where large numbers of samples require screening.

OBJECTIVES

To develop, characterise and evaluate a rapid UHP-HILIC-MS-based method for the analysis of polar metabolites in rat urine and then extend the capabilities of this approach by the addition of IMS to the system.

METHODS

A rapid untargeted HILIC LC-MS/MS profiling method for the analysis of small polar molecules has been developed. The 3.3 min separation used a Waters BEH amide (1 mm ID) analytical column on a Waters Synapt G2-Si Q-Tof enabled with ion mobility spectrometry (IMS). The methodology, was applied to the metabolic profiling of a series of rodent urine samples from vehicle-treated control rats and animals administered tienilic acid. The same separation was subsequently linked to IMS and MS to evaluate the benefits that IMS might provide for metabolome characterisation.

RESULTS

The rapid HILIC-MS method was successfully applied to rapid analysis of rat urine and found, based on the data generated from the data acquired for the pooled quality control samples analysed at regular intervals throughout the analysis, to be robust. Peak area and retention times for the compounds detected in these samples showed good reproducibility across the batch. When used to profile the urine samples obtained from vehicle-dosed control and those administered tienilic acid the HILIC-MS method detected 3007 mass/retention time features. Analysis of the same samples using HILIC-IMS-MS enabled the detection of 6711 features. Provisional metabolite identification for a number of compounds was performed using the high collision energy MS/MS information compared against the Metlin MS/MS database and, in addition, both calculated and measured CCS values from an experimentally derived CCS database.

CONCLUSION

A rapid metabolic profiling method for the analysis of polar metabolites has been developed. The method has the advantages of speed and both reducing sample and solvent consumption compared to conventional profiling methods. The addition of IMS added an additional dimension for feature detection and the identification of metabolites.

Getting to the heart of the sphingolipid riddle

Obesity, Type 2 Diabetes, and Metabolic Syndrome induce dyslipidemia resulting in inundation of peripheral organs with fatty acids. These not only serve as substrates for energy production, but also contribute to aberrant production of bioactive lipids. Moreover, lipid metabolism is affected in many cardiac disorders including heart failure, ischemia reperfusion injury, and others. While lipids serve crucial homeostatic roles, perturbing biosynthesis of lipid mediators leads to aberrant cell signaling, which contributes to maladaptive cardiovascular programs. Bioactive sphingolipids, in particular, have been implicated in pathophysiology in the heart and vasculature by a variety of studies in cells, animal models, and humans. Because of the burgeoning interest in sphingolipid-driven biology in the cardiovascular system, it is necessary to discuss the experimental considerations for studying sphingolipid metabolism and signaling, emphasizing the caveats to some widely available experimental tools and approaches. Additionally, there is a growing appreciation for the diversity of ceramide structures generated via specific enzymes and bearing disparate cellular functions. While targeting these individual species and enzymes constitutes a major advance, studies show that sphingolipid synthesis readily adapts to compensate for experimental targeting of any individual pathway, thereby convoluting data interpretation. Furthermore, though some molecular mechanisms of sphingolipid action are known, signaling pathways impacted by sphingolipids remain incompletely understood. In this review, we discuss these issues and highlight recent studies as well as future directions that may extend our understanding of the metabolism and signaling actions of these enigmatic lipids in the cardiovascular context.