Eicosapentaenoic acid inhibits glucose-induced membrane cholesterol crystalline domain formation through a potent antioxidant mechanism

Functional Lipids and Cardiovascular Disease Reduction: A Concise Review

Functional lipids are dietary substances that may have an impact on human health by lowering the risk of chronic illnesses and enhancing the quality of life. Numerous functional lipids have been reported to have potential health benefits in the prevention, management, and treatment of cardiovascular disease, the leading cause of death in the United States. However, there is still insufficient and contradictory information in the literature about their effectiveness and associated mechanisms of action. The objective of this review, therefore, is to evaluate available literature regarding these functional lipids and their health benefits. Various studies have been conducted to understand the links between functional lipids and the prevention and treatment of chronic diseases. Recent studies on phytosterols have reported that CLA, medium-chain triglycerides, and omega-3 and 6 fatty acids have positive effects on human health. Also, eicosanoids, which are the metabolites of these fatty acids, are produced in relation to the ratio of omega-3 to omega-6 polyunsaturated fatty acids and may modulate disease conditions. These functional lipids are available either in dietary or supplement forms and have been proven to be efficient, accessible, and inexpensive to be included in the diet. However, further research is required to properly elucidate the dosages, dietary intake, effectiveness, and their mechanisms of action in addition to the development of valid disease biomarkers and long-term effects in humans.

Bleeding Risk in Patients Receiving Omega-3 Polyunsaturated Fatty Acids: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

BACKGROUND

There is a potential concern about increased bleeding risk in patients receiving omega-3 polyunsaturated fatty acids (PUFAs). The aims of this study-level meta-analysis were to determine the risk of bleeding and to assess whether this relationship is linked to the received dose of omega-3 PUFAs or the background use of antiplatelet treatment.

METHODS AND RESULTS

Electronic databases were searched through May 2023 to identify randomized clinical trials of patients receiving omega-3 PUFAs. Overall bleeding events, including fatal and central nervous system events, were identified and compared with those of a control group. A total of 120 643 patients from 11 randomized clinical trials were included. There was no difference in the pooled meta-analytic events of bleeding among patients receiving omega-3 PUFAs and those in the control group (rate ratio [RR], 1.09 [95% CI, 0.91-1.31]; P=0.34). Likewise, the incidence of hemorrhagic stroke, intracranial bleeding, and gastrointestinal bleeding were similar. A prespecified analysis was performed in patients receiving high-dose purified eicosapentaenoic acid (EPA), which demonstrated a 50% increase in the relative risk of bleeding but only a modest increase in the absolute risk of bleeding (0.6%) when compared with placebo. Bleeding risk was associated with the dose of EPA (risk difference, 0.24 [95% CI, 0.05-0.43]; P=0.02) but not the background use of antiplatelet therapy (risk difference, -0.01 [95% CI, -0.02 to 0]; P=0.056).

CONCLUSIONS

Omega-3 PUFAs were not associated with increased bleeding risk. Patients receiving high-dose purified EPA may incur additional bleeding risk, although its clinical significance is very modest.

Do patients benefit from omega-3 fatty acids?

Omega-3 fatty acids (O3FAs) possess beneficial properties for cardiovascular (CV) health and elevated O3FA levels are associated with lower incident risk for CV disease (CVD.) Yet, treatment of at-risk patients with various O3FA formulations has produced disparate results in large, well-controlled and well-conducted clinical trials. Prescription formulations and fish oil supplements containing low-dose mixtures of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have routinely failed to prevent CV events in primary and secondary prevention settings when added to contemporary care, as shown most recently in the STRENGTH and OMEMI trials. However, as observed in JELIS, REDUCE-IT, and RESPECT-EPA, EPA-only formulations significantly reduce CVD events in high-risk patients. The CV mechanism of action of EPA, while certainly multifaceted, does not depend solely on reductions of circulating lipids, including triglycerides (TG) and LDL, and event reduction appears related to achieved EPA levels suggesting that the particular chemical and biological properties of EPA, as compared to DHA and other O3FAs, may contribute to its distinct clinical efficacy. In vitro and in vivo studies have shown different effects of EPA compared with DHA alone or EPA/DHA combination treatments, on atherosclerotic plaque morphology, LDL and membrane oxidation, cholesterol distribution, membrane lipid dynamics, glucose homeostasis, endothelial function, and downstream lipid metabolite function. These findings indicate that prescription-grade, EPA-only formulations provide greater benefit than other O3FAs formulations tested. This review summarizes the clinical findings associated with various O3FA formulations, their efficacy in treating CV disease, and their underlying mechanisms of action.

Mechanistic aspects of ameliorative effects of Eicosapentanoic acid ethyl ester on methotrexate-evoked testiculopathy in rats

Disrupted spermatogenesis and testicular injury are among the devastating outcomes of methotrexate. A major contributor to methotrexate-induced testiculopathy is oxidative damage which triggers apoptosis and altered autophagy responses. Eicosapentaenoic acid ethyl ester (EPA-E) is an antihyperlipidemic derivative of omega-3 fatty acids that exhibited affinity to peroxisome proliferator-activated receptor-γ (PPAR-γ) that possesses both antioxidant and autophagy modulating properties. This is an exploratory study aiming at assessing the effectiveness of EPA-E to alleviate testicular damage induced by methotrexate. The specific exploratory hypothesis of this experiment is: EPA-E administration for 1 week to methotrexate-treated rats reduces testicular damage compared to control rats. As a secondary outcome, we were interested in identifying the implicated mechanism that mediates the action of EPA-E. In adult male Wistar rats, testiculopathy was achieved by a single methotrexate injection (20 mg/kg, ip). Rats received vehicle, EPA-E (0.3 g/kg/day, po) alone or with selective PPAR-γ antagonist (bisphenol A diglycidyl ether, BADGE) at 30 mg/kg/day, ip for 1 week. EPA-E recuperated methotrexate-attenuated serum total testosterone while reduced testicular inflammation and oxidative stress, restoring superoxide dismutase (SOD) while reducing malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG). Methotrexate-induced testicular apoptosis (caspase-3 and p53) was suppressed upon EPA-E treatment. Besides, EPA-E curbed methotrexate-induced abnormal autophagy by downregulating LC3A/B and beclin-1. Interestingly, BADGE-coadministration reversed EPA-E beneficial actions. Collectively, our findings suggest PPAR-γ role in EPA-E-mediated mitigation of methotrexate-evoked testiculopathy via suppression of oxidative stress, apoptosis, as well as abnormal autophagy. Furthermore, EPA-E could be used as a preventive therapy for some testiculopathies mediated by oxidative stress.

Variability in the Clinical Effects of the Omega-3 Polyunsaturated Fatty Acids DHA and EPA in Cardiovascular Disease-Possible Causes and Future Considerations

Cardiovascular disease (CVD) that includes myocardial infarction and stroke, is the leading cause of mortality worldwide. Atherosclerosis, the primary underlying cause of CVD, can be controlled by pharmacological and dietary interventions, including n-3 polyunsaturated fatty acid (PUFA) supplementation. n-3 PUFA supplementation, primarily consisting of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), has shown promise in reducing atherosclerosis by modulating risk factors, including triglyceride levels and vascular inflammation. n-3 PUFAs act by replacing pro-inflammatory fatty acid types in cell membranes and plasma lipids, by regulating transcription factor activity, and by inducing epigenetic changes. EPA and DHA regulate cellular function through shared and differential molecular mechanisms. Large clinical studies on n-3 PUFAs have reported conflicting findings, causing confusion among the public and health professionals. In this review, we discuss important factors leading to these inconsistencies, in the context of atherosclerosis, including clinical study design and the differential effects of EPA and DHA on cell function. We propose steps to improve clinical and basic experimental study design in order to improve supplement composition optimization. Finally, we propose that understanding the factors underlying the poor response to n-3 PUFAs, and the development of molecular biomarkers for predicting response may help towards a more personalized treatment.

Biotechnological production of omega-3 fatty acids: current status and future perspectives

Omega-3 fatty acids, including alpha-linolenic acids (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), have shown major health benefits, but the human body's inability to synthesize them has led to the necessity of dietary intake of the products. The omega-3 fatty acid market has grown significantly, with a global market from an estimated USD 2.10 billion in 2020 to a predicted nearly USD 3.61 billion in 2028. However, obtaining a sufficient supply of high-quality and stable omega-3 fatty acids can be challenging. Currently, fish oil serves as the primary source of omega-3 fatty acids in the market, but it has several drawbacks, including high cost, inconsistent product quality, and major uncertainties in its sustainability and ecological impact. Other significant sources of omega-3 fatty acids include plants and microalgae fermentation, but they face similar challenges in reducing manufacturing costs and improving product quality and sustainability. With the advances in synthetic biology, biotechnological production of omega-3 fatty acids via engineered microbial cell factories still offers the best solution to provide a more stable, sustainable, and affordable source of omega-3 fatty acids by overcoming the major issues associated with conventional sources. This review summarizes the current status, key challenges, and future perspectives for the biotechnological production of major omega-3 fatty acids.

Role of Omega-3 Fatty Acids in Cardiovascular Disease: the Debate Continues

PURPOSE OF REVIEW

The omega-3 fatty acids (n3-FAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have recently undergone testing for their ability to reduce residual cardiovascular (CV) risk among statin-treated subjects. The outcome trials have yielded highly inconsistent results, perhaps attributable to variations in dosage, formulation, and composition. In particular, CV trials using icosapent ethyl (IPE), a highly purified ethyl ester of EPA, reproducibly reduced CV events and progression of atherosclerosis compared with mixed EPA/DHA treatments. This review summarizes the mechanistic evidence for differences among n3-FAs on the development and manifestations of atherothrombotic disease.

RECENT FINDINGS

Large randomized clinical trials with n3-FAs have produced discordant outcomes despite similar patient profiles, doses, and triglyceride (TG)-lowering effects. A large, randomized trial with IPE, a prescription EPA only formulation, showed robust reduction in CV events in statin treated patients in a manner proportional to achieved blood EPA concentrations. Multiple trials using mixed EPA/DHA formulations have not shown such benefits, despite similar TG lowering. These inconsistencies have inspired investigations into mechanistic differences among n3-FAs, as EPA and DHA have distinct membrane interactions, metabolic products, effects on cholesterol efflux, antioxidant properties, and tissue distribution. EPA maintains normal membrane cholesterol distribution, enhances endothelial function, and in combination with statins improves features implicated in plaque stability and reduces lipid content of plaques. Insights into reductions in residual CV risk have emerged from clinical trials using different formulations of n3-FAs. Among high-risk patients on contemporary care, mixed n3-FA formulations showed no reduction in CV events. The distinct benefits of IPE in multiple trials may arise from pleiotropic actions that correlate with on-treatment EPA levels beyond TG-lowering. These effects include altered platelet function, inflammation, cholesterol distribution, and endothelial dysfunction. Elucidating such mechanisms of vascular protection for EPA may lead to new interventions for atherosclerosis, a disease that continues to expand worldwide.

Cholesterol crystals and atherosclerotic plaque instability: Therapeutic potential of Eicosapentaenoic acid

Atherosclerotic plaques associated with acute coronary syndromes (ACS), i.e. culprit lesions, frequently feature a ruptured fibrous cap with thrombotic complications. On imaging, these plaques exhibit a low attenuation, lipid-rich, necrotic core containing cholesterol crystals and are inherently unstable. Indeed, cholesterol crystals are causally associated with plaque vulnerability in vivo; their formation results from spontaneous self-assembly of cholesterol molecules. Cholesterol homeostasis is a central determinant of the physicochemical conditions leading to crystal formation, which are favored by elevated membrane free cholesterol content in plaque endothelial cells, smooth muscle cells, monocyte-derived macrophages, and foam cells, and equally by lipid oxidation. Emerging evidence from imaging trials in patients with coronary heart disease has highlighted the impact of intervention involving the omega-3 fatty acid, eicosapentaenoic acid (EPA), on vulnerable, low attenuation atherosclerotic plaques. Thus, EPA decreased features associated with unstable plaque by increasing fibrous cap thickness in statin-treated patients, by reducing lipid volume and equally attenuating intraplaque inflammation. Importantly, atherosclerotic plaques rapidly incorporate EPA; indeed, a high content of EPA in plaque tissue is associated with decreased plaque inflammation and increased stability. These findings are entirely consistent with the major reduction seen in cardiovascular events in the REDUCE-IT trial, in which high dose EPA was administered as its esterified precursor, icosapent ethyl (IPE); moreover, clinical benefit was proportional to circulating EPA levels. Eicosapentaenoic acid is efficiently incorporated into phospholipids, where it modulates cholesterol-enriched domains in cell membranes through physicochemical lipid interactions and changes in rates of lipid oxidation. Indeed, biophysical analyses indicate that EPA exists in an extended conformation in membranes, thereby enhancing normal cholesterol distribution while reducing propagation of free radicals. Such effects mitigate cholesterol aggregation and crystal formation. In addition to its favorable effect on cholesterol domain structure, EPA/IPE exerts pleiotropic actions, including antithrombotic, antiplatelet, anti-inflammatory, and proresolving effects, whose plaque-stabilizing potential cannot be excluded. Docosahexaenoic acid is distinguished from EPA by a higher degree of unsaturation and longer carbon chain length; DHA is thus predisposed to changes in its conformation with ensuing increase in membrane lipid fluidity and promotion of cholesterol aggregation into discrete domains. Such distinct molecular effects between EPA and DHA are pronounced under conditions of high cellular cholesterol content and oxidative stress. This review will focus on the formation and role of cholesterol monohydrate crystals in destabilizing atherosclerotic plaques, and on the potential of EPA as a therapeutic agent to attenuate the formation of deleterious cholesterol membrane domains and of cholesterol crystals. Such a therapeutic approach may translate to enhanced plaque stability and ultimately to reduction in cardiovascular risk.

Comparative efficacy of omega-3 polyunsaturated fatty acids on major cardiovascular events: A network meta-analysis of randomized controlled trials

The role of omega-3 polyunsaturated fatty acids (PUFAs) in primary and secondary prevention on major cardiovascular events (MCE) is inconclusive due to the potential heterogeneity in study designs of formulas, dosages, and ratios of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from the findings of previous randomized controlled trials (RCTs). Here we conducted a comprehensive narrative review of pre-clinical studies and updated a network meta-analysis (NMA) to determine the comparative efficacy against MCE with different EPA/DHA dosages and formulas. We found that pure EPA was ranked the best option in the secondary prevention (hazard ratio: 0.72, 95% confidence interval: 0.65 to 0.81) from the NMA of 39 RCTs with 88,359 participants. There was no evidence of omega-3 PUFAs' efficacy in primary prevention. The mechanisms of omega-3 PUFAs' cardiovascular protection might link to the effects of anti-inflammation and stabilization of endothelial function from PUFA's derivatives including eicosanoids and the special pre-resolving mediators (SPMs).

Recent Updates in Hypertriglyceridemia Management for Cardiovascular Disease Prevention

PURPOSE OF REVIEW

Mounting evidence continues to support the causal role of triglyceride-rich lipoproteins (TRL) in the development of atherosclerotic cardiovascular disease (ASCVD). Substantial residual ASCVD risk remains among high-risk patients who have elevated triglycerides despite reduction in low-density lipoprotein cholesterol (LDL-C) with statin therapy. Ongoing research efforts have focused on evaluating triglyceride-lowering therapies among patients with hypertriglyceridemia.

RECENT FINDINGS

The REDUCE-IT trial showed that the addition of icosapent ethyl, a highly purified form of eicosapentaenoic acid (EPA), can reduce vascular events among statin-treated individuals with elevated triglycerides who have either clinical ASCVD or diabetes plus another risk factor. Although additional evidence for EPA has emerged from other trials, conflicting results have been reported by subsequent trials that tested different omega-3 fatty acid formulations. Randomized clinical trials have not demonstrated incremental ASCVD benefit of fibrates on background of statin therapy, but fibrates are used to help prevent pancreatitis in patients with severe hypertriglyceridemia. Selective inhibitors of apolipoprotein C-III (apoC3) and angiopoietin-like protein 3 (ANGPTL3), proteins that are involved in metabolism of TRLs by regulating lipoprotein lipase, have been tested in selected patient populations and showed significant reduction in triglyceride and LDL-C levels. Statin therapy continues to be the cornerstone of pharmacologic reduction of cardiovascular risk. High-dose EPA in the form of icosapent ethyl has been demonstrated to have cardiovascular benefit on top of statins in persons with elevated triglycerides at high ASCVD risk. Ongoing clinical trials are evaluating novel selective therapies such as apoC3 and ANGPTL3 inhibitors.

Killing the Culprit: Pharmacological Solutions to Get Rid of Cholesterol Crystals

Cholesterol crystals (CCs) play a key role in the pathophysiology of cardiovascular diseases (CVD) via triggering inflammation, plaque formation and subsequently plaque rupture. Although statins can stabilize plaques via calcification and alteration of the lipid composition within plaques, there is still a high residual risk of CVD events among statins users. Several studies have tried to blunt the detrimental effects of cholesterol crystals by pharmacological interventions. Cyclodexterins (CDs) and other nanoformulations, including polymers of CDs and liposomes, have the ability to dissolve CCs in vitro and in vivo. CDs were the first in their class that entered clinical trials and showed promising results, though their ototoxicity outweighed their benefits. Moreover, small molecules with structural similarity to cholesterol may also perturb cholesterol-cholesterol interactions and prevent from expansion of 2D crystalline domains to large 3D CCs. The results from ethyl eicosapentaenoic acid and ursodeoxycholic acid were encouraging and worth further consideration. In this review, the significance of CCs in pathogenesis of CVD is discussed and pharmacological agents with the ability to dissolve CCs or prevent from CCs formation are introduced.

Controversies in the Use of Omega-3 Fatty Acids to Prevent Atherosclerosis

PURPOSE OF REVIEW

We discuss current controversies in the clinical use of omega-3 fatty acids (FA), primarily eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and examine discrepancies between recent trials. Furthermore, we discuss potential side effects reported in these studies and the role of mixed omega-3 FA dietary supplements and concerns about their use.

RECENT FINDINGS

REDUCE-IT showed that addition of icosapent ethyl, a highly purified form of EPA, can reduce risk of cardiovascular events among statin-treated individuals with high triglycerides. Additional supportive evidence for EPA has come from other trials and meta-analyses of omega-3 FA therapy. In contrast, trials of mixed EPA/DHA products have consistently failed to improve cardiovascular outcomes. Discrepancies in results reported in RCTs could be explained by differences in omega-3 FA products, dosing, study populations, and study designs including the placebo control formulation. Evidence obtained from highly purified forms should not be extrapolated to other mixed formulations, including "over-the-counter" omega-3 supplements. Targeting TG-rich lipoproteins represents a new frontier for mitigating ASCVD risk. Clinical and basic research evidence suggests that the use of omega-3 FA, specifically EPA, appears to slow atherosclerosis by reducing triglyceride-rich lipoproteins and/or inflammation, therefore addressing residual risk of clinical ASCVD.

Omega-3 Polyunsaturated Fatty Acids-Vascular and Cardiac Effects on the Cellular and Molecular Level (Narrative Review)

In the prevention and treatment of cardiovascular disease, in addition to the already proven effective treatment of dyslipidemia, hypertension and diabetes mellitus, omega-3 polyunsaturated fatty acids (n-3 PUFAs) are considered as substances with additive effects on cardiovascular health. N-3 PUFAs combine their indirect effects on metabolic, inflammatory and thrombogenic parameters with direct effects on the cellular level. Eicosapentaenoic acid (EPA) seems to be more efficient than docosahexaenoic acid (DHA) in the favorable mitigation of atherothrombosis due to its specific molecular properties. The inferred mechanism is a more favorable effect on the cell membrane. In addition, the anti-fibrotic effects of n-3 PUFA were described, with potential impacts on heart failure with a preserved ejection fraction. Furthermore, n-3 PUFA can modify ion channels, with a favorable impact on arrhythmias. However, despite recent evidence in the prevention of cardiovascular disease by a relatively high dose of icosapent ethyl (EPA derivative), there is still a paucity of data describing the exact mechanisms of n-3 PUFAs, including the role of their particular metabolites. The purpose of this review is to discuss the effects of n-3 PUFAs at several levels of the cardiovascular system, including controversies.

Role of EPA in Inflammation: Mechanisms, Effects, and Clinical Relevance

Many chronic inflammatory processes are linked with the continuous release of inflammatory mediators and the activation of harmful signal-transduction pathways that are able to facilitate disease progression. In this context atherosclerosis represents the most common pathological substrate of coronary heart disease, and the characterization of the disease as a chronic low-grade inflammatory condition is now validated. The biomarkers of inflammation associated with clinical cardiovascular risk support the theory that targeted anti-inflammatory treatment appears to be a promising strategy in reducing residual cardiovascular risk. Several literature data highlight cardioprotective effects of the long-chain omega-3 polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA). This PUFA lowers plasma triglyceride levels and has potential beneficial effects on atherosclerotic plaques. Preclinical studies reported that EPA reduces both pro-inflammatory cytokines and chemokines levels. Clinical studies in patients with coronary artery disease that receive pharmacological statin therapy suggest that EPA may decrease plaque vulnerability preventing plaque progression. This review aims to provide an overview of the links between inflammation and cardiovascular risk factors, importantly focusing on the role of diet, in particular examining the proposed role of EPA as well as the success or failure of standard pharmacological therapy for cardiovascular diseases.

Icosapent Ethyl Reduces Ischemic Events in Patients With a History of Previous Coronary Artery Bypass Grafting: REDUCE-IT CABG

BACKGROUND

Despite advances in surgery and pharmacotherapy, there remains significant residual ischemic risk after coronary artery bypass grafting surgery.

METHODS

In REDUCE-IT (Reduction of Cardiovascular Events With Icosapent Ethyl-Intervention Trial), a multicenter, placebo-controlled, double-blind trial, statin-treated patients with controlled low-density lipoprotein cholesterol and mild to moderate hypertriglyceridemia were randomized to 4 g daily of icosapent ethyl or placebo. They experienced a 25% reduction in risk of a primary efficacy end point (composite of cardiovascular death, myocardial infarction, stroke, coronary revascularization, or hospitalization for unstable angina) and a 26% reduction in risk of a key secondary efficacy end point (composite of cardiovascular death, myocardial infarction, or stroke) when compared with placebo. The current analysis reports on the subgroup of patients from the trial with a history of coronary artery bypass grafting.

RESULTS

Of the 8179 patients randomized in REDUCE-IT, a total of 1837 (22.5%) had a history of coronary artery bypass grafting, with 897 patients randomized to icosapent ethyl and 940 to placebo. Baseline characteristics were similar between treatment groups. Randomization to icosapent ethyl was associated with a significant reduction in the primary end point (hazard ratio [HR], 0.76 [95% CI, 0.63-0.92]; P=0.004), in the key secondary end point (HR, 0.69 [95% CI, 0.56-0.87]; P=0.001), and in total (first plus subsequent or recurrent) ischemic events (rate ratio, 0.64 [95% CI, 0.50-0.81]; P=0.0002) compared with placebo. This yielded an absolute risk reduction of 6.2% (95% CI, 2.3%-10.2%) in first events, with a number needed to treat of 16 (95% CI, 10-44) during a median follow-up time of 4.8 years. Safety findings were similar to the overall study: beyond an increased rate of atrial fibrillation/flutter requiring hospitalization for at least 24 hours (5.0% vs 3.1%; P=0.03) and a nonsignificant increase in bleeding, occurrences of adverse events were comparable between groups.

CONCLUSIONS

In REDUCE-IT patients with a history of coronary artery bypass grafting, treatment with icosapent ethyl was associated with significant reductions in first and recurrent ischemic events. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01492361.

Improving Appropriate Use of Omega-3 Fatty Acids for Patients With Dyslipidemia: Effect of Online CME

Hypertriglyceridemia is associated with an increased risk of atherosclerotic cardiovascular (CV) disease. Clinical trials have demonstrated the effectiveness of eicosapentaenoic acid ethyl ester (EPA), an omega-3 polyunsaturated fatty acid, on triglyceride lowering and on CV risk reduction. However, many clinicians have limited understanding of the effects of EPA and limited experience using EPA to reduce the risk of CV disease. An analysis was conducted to determine whether an online continuing medical education (CME) intervention could improve knowledge and competence of primary care physicians (PCPs) and cardiologists related to the role of EPA in management of CV risk in patients with dyslipidemia. The intervention comprised 2 online video-based CME activities. The effects of education were assessed for learners who completed 4 pre- and postassessment questions for each activity, using a matched pre-/postassessment design. For all questions combined, a McNemar's χ2 test assessed differences from pre- to postassessment. Matched-learner data indicated that 34% of PCPs improved their knowledge as a result of participating in the activities, and 42% had their knowledge reinforced. Among cardiologists, 28% improved their knowledge, and 61% had their knowledge reinforced. For these learner subsets, there was a significant 17% relative increase in self-assessed confidence in appropriate use of EPA for PCPs (n = 1644, P < 0.001) and a 12% increase for cardiologists (n = 524; P < 0.001). The improvements observed in this online CME intervention demonstrate the benefits of educating the appropriate target audience base and suggest that this type of intervention can translate into improvements in clinical care.

Omega-3 and omega-6 fatty acids have distinct effects on endothelial fatty acid content and nitric oxide bioavailability

Treatment with high dose icosapent ethyl (IPE), an ethyl ester of the omega-3 fatty acid eicosapentaenoic acid (EPA), significantly reduced ischemic events in patients with either cardiovascular disease (CV) or diabetes plus other risk factors (REDUCE-IT) but the mechanism is not well understood.  We compared the effects of EPA, docosahexaenoic acid (DHA), and the omega-6 fatty acid arachidonic acid (AA) on bioavailability of nitric oxide (NO) and fatty acid composition. Human umbilical vein endothelial cells (HUVECs) were pretreated with EPA, DHA, or AA (10 µM). Cells were stimulated with calcium ionophore and NO and peroxynitrite (ONOO^-) were measured using porphyrinic nanosensors. Levels of EPA, DHA, AA and other fatty acids were measured by gas chromatography (GC). EPA treatment caused the greatest NO release (18%, p < 0.001) and reduction in ONOO^- (13%, p < 0.05) compared to control; the [NO]/[ ONOO^-] ratio increased by 35% (p < 0.001). DHA treatment increased NO levels by 12% (p < 0.01) but had no effect on ONOO^- release. AA did not affect either NO or ONOO^- release.  Fatty acid treatments increased their respective levels in endothelial cells.  EPA levels increased 10-fold to 4.59 mg/g protein (p < 0.001) with EPA treatment and the EPA/AA ratio increased by 10-fold (p < 0.001) compared to vehicle.  Only EPA increased docosapentaenoic acid (DPA, omega-3) levels by 2-fold (p < 0.001). AA alone decreased the EPA/AA ratio 4-fold (p<0.001). These findings support a preferential benefit of EPA on endothelial function and omega-3 fatty acid content.

EPA and DHA containing phospholipids have contrasting effects on membrane structure

Omega-3 FAs EPA and DHA influence membrane fluidity, lipid rafts, and signal transduction. A clinical trial, Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial, demonstrated that high-dose EPA (4 g/d icosapent ethyl) reduced composite cardiovascular events in statin-treated high-risk patients. EPA benefits correlated with on-treatment levels, but similar trials using DHA-containing formulations did not show event reduction. We hypothesized that differences in clinical efficacy of various omega-3 FA preparations could result from differential effects on membrane structure. To test this, we used small-angle X-ray diffraction to compare 1-palmitoyl-2-eicosapentaenoyl-sn-glycero-3-phosphocholine (PL-EPA), 1-palmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine (PL-DHA), and 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PL-AA) in membranes with and without 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and cholesterol. Electron density profiles (electrons/Å3 vs. Å) were used to determine membrane structure, including membrane width (d-space). PL-EPA and PL-DHA had similar membrane structures without POPC and/or cholesterol but had contrasting effects in the presence of POPC and cholesterol. PL-EPA increased membrane hydrocarbon core electron density over an area of ±0-10 Å from the center, indicating an extended orientation. PL-DHA increased electron density in the phospholipid head group region, concomitant with disordering in the hydrocarbon core and a similar d-space (58 Å). Adding equimolar amounts of PL-EPA and PL-DHA produced changes that were attenuated compared with their separate effects. PL-AA increased electron density centered ±12 Å from the membrane center. The contrasting effects of PL-EPA, PL-DHA, and PL-AA on membrane structure may contribute to differences observed in the biological activities and clinical actions of various omega-3 FAs.

Obese rats intervened with Rhizoma coptidis revealed differential gene expression and microbiota by serum metabolomics

Background

Integrating systems biology is an approach for investigating metabolic diseases in humans. However, few studies use this approach to investigate the mechanism by which Rhizoma coptidis (RC) reduces the effect of lipids and glucose on high-fat induced obesity in rats.

Methods

Twenty-four specific pathogen-free (SPF) male Sprague–Dawley rats (80 ± 10 g) were used in this study. Serum metabolomics were detected by ultra-high-performance liquid chromatography coupled with quadrupole-time-of-flight tandem mass spectrometry. Liver tissue and cecum feces were used for RNA-Seq technology and 16S rRNA gene sequencing, respectively.

Results

We identified nine potential biomarkers, which are differential metabolites in the Control, Model and RC groups, including linoleic acid, eicosapentaenoic acid, arachidonic acid, stearic acid, and L-Alloisoleucine (p < 0.01). The liver tissue gene expression profile indicated the circadian rhythm pathway was significantly affected by RC (Q ≤ 0.05). A total of 149 and 39 operational taxonomic units (OTUs), which were highly associated with biochemical indicators and potential biomarkers in the cecum samples (FDR ≤ 0.05), respectively, were identified.

Conclusion

This work provides information to better understand the mechanism of the effect of RC intervention on hyperlipidemia and hypoglycemic effects in obese rats. The present study demonstrates that integrating systems biology may be a powerful tool to reveal the complexity of metabolic diseases in rats intervened by traditional Chinese medicine.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03382-3.

EPA's pleiotropic mechanisms of action: a narrative review

Treatment with icosapent ethyl 4 g/day, a highly purified and stable ethyl ester of eicosapentaenoic acid (EPA), demonstrated a significant reduction in atherosclerotic cardiovascular disease (ASCVD) events and death in REDUCE-IT. However, analyses of REDUCE-IT and meta-analyses have suggested that this clinical benefit is greater than can be achieved by triglyceride reduction alone. EPA therefore may have additional pleiotropic effects, including anti-inflammatory and anti-aggregatory mechanisms. EPA competes with arachidonic acid for cyclooxygenase and lipoxygenase, producing anti-inflammatory and anti-aggregatory metabolites rather than the more deleterious metabolites associated with arachidonic acid. Changing the EPA:arachidonic acid ratio may shift metabolic status from pro-inflammatory/pro-aggregatory to anti-inflammatory/anti-aggregatory. EPA also has antioxidant effects and increases synthesis of nitric oxide. Incorporation of EPA into phospholipid bilayers influences membrane structure and may help to prevent cardiac arrhythmias. Clinically, this may translate into improved vascular health, including regression of atherosclerotic plaque. Overall, EPA has a range of pleiotropic effects that contribute to a reduction in ASCVD.

Cardiovascular effects of omega-3 fatty acids: Hope or hype?

Omega-3 fatty acids have emerged as a new option for controlling the residual risk for cardiovascular disease (CVD) in the statin era after a clinical trial (REDUCE-IT) reported positive results with icosapent ethyl (IPE) in patients receiving maximally tolerated statin therapy. However, another trial which used high dose eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) combination (STRENGTH) has failed. Together, these results raise clinically important questions. Are effects of omega-3 fatty acids neutral or beneficial in patients on statin therapy, or perhaps even harmful? The current contradictory results could be attributed to different types of omega-3 fatty acids (only EPA or combination of EPA + DHA), doses (higher vs. lower dose) of omega-3 fatty acids or different comparators (corn oil or mineral oil), as well as the underlying severity of the CVD risk or use of statins. Together with these issues, we will discuss different biological and clinical effects of various types of omega-3 fatty acids and then interpret different results of past and current clinical studies and propose practical suggestions, which could be applied in patient management.

The Truth About Fish (Oil) in the Treatment of Dyslipidemia

PURPOSE OF REVIEW

To discuss the effect of fish oils on dyslipidemias and associated disorders.

RECENT FINDINGS

The most important lipid effect of fish oils is reducing plasma triglycerides and the main potential protection against cardiovascular events is very probably mediated also through other mechanisms including anti-inflammatory ones. The best results are available for omega-3 fatty acids, namely, eicosapentaenoic acid. Less evidence is available for the impact of ω-3 fatty acids on liver steatosis/steatohepatitis and acute pancreatitis. In addition, particular fish oils have variable content of saturated and unsaturated fatty acids with different anti- or pro-oxidative potential, and the suboptimal ratio of these compounds could attenuate or abolish their beneficial properties. Fish products with optimal proportion of fatty acids, particularly high content of eicosapentaenoic acid, could be recommended to patients with dyslipidemias, especially to those at high risk for cardiovascular disease; less evidence is available for liver disease and acute pancreatitis.

Cardiovascular Impact of Nutritional Supplementation With Omega-3 Fatty Acids: JACC Focus Seminar

Omega-3 polyunsaturated fatty acids (PUFAs) are a key component of a heart-healthy diet. For patients without clinical atherosclerotic cardiovascular disease, 2 or more servings of fatty fish per week is recommended to obtain adequate intake of omega-3 PUFAs. If this not possible, dietary supplementation with an appropriate fish oil may be reasonable. Supplementation with omega-3 PUFA capsules serves 2 distinct but overlapping roles: treatment of hypertriglyceridemia and prevention of cardiovascular events. Marine-derived omega-3 PUFAs reduce triglycerides and have pleiotropic effects including decreasing inflammation, improving plaque composition and stability, and altering cellular membranes. Clinical trial data have shown inconsistent results with omega-3 PUFAs improving cardiovascular outcomes. In this paper, the authors provide an overview of PUFAs and a summary of key clinical trial data. Recent trial data suggest the use of prescription eicosapentaenoic acid ethyl ester for atherosclerotic cardiovascular disease event reduction in selected populations.

Do Eicosapentaenoic Acid and Docosahexaenoic Acid Have the Potential to Compete against Each Other?

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are n-3 polyunsaturated fatty acids (PUFAs) consumed in low abundance in the Western diet. Increased consumption of n-3 PUFAs may have beneficial effects for a wide range of physiological outcomes including chronic inflammation. However, considerable mechanistic gaps in knowledge exist about EPA versus DHA, which are often studied as a mixture. We suggest the novel hypothesis that EPA and DHA may compete against each other through overlapping mechanisms. First, EPA and DHA may compete for residency in membrane phospholipids and thereby differentially displace n-6 PUFAs, which are highly prevalent in the Western diet. This would influence biosynthesis of downstream metabolites of inflammation initiation and resolution. Second, EPA and DHA exert different effects on plasma membrane biophysical structure, creating an additional layer of competition between the fatty acids in controlling signaling. Third, DHA regulates membrane EPA levels by lowering its rate of conversion to EPA's elongation product n-3 docosapentaenoic acid. Collectively, we propose the critical need to investigate molecular competition between EPA and DHA in health and disease, which would ultimately impact dietary recommendations and precision nutrition trials.

The Road to Approval: a Perspective on the Role of Icosapent Ethyl in Cardiovascular Risk Reduction

PURPOSE OF REVIEW

Epidemiological studies have long suggested the cardiovascular benefits of omega-3 fatty acids (OM3FAs). However, until recently, clinical trials using OM3FAs have been largely negative with respect to their cardioprotective effects. In this review, we aim to summarize key clinical trials, examine the clinical benefits of eicosapentaenoic acid (EPA) and potential mechanisms, and review the changes in guidelines and recommendations.

RECENT FINDINGS

The Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial (REDUCE-IT) has demonstrated significant cardiovascular mortality benefits of purified EPA ethyl ester, with a 25% relative risk reduction in major cardiovascular events. As first of its class to be approved, icosapent ethyl offers a new option to further reduce cardiovascular risks in patients already treated with maximally tolerated statins.

Mechanistic insights into cardiovascular protection for omega-3 fatty acids and their bioactive lipid metabolites

Patients with well-controlled low-density lipoprotein cholesterol levels, but persistent high triglycerides, remain at increased risk for cardiovascular events as evidenced by multiple genetic and epidemiologic studies, as well as recent clinical outcome trials. While many trials of low-dose ω3-polyunsaturated fatty acids (ω3-PUFAs), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) have shown mixed results to reduce cardiovascular events, recent trials with high-dose ω3-PUFAs have reignited interest in ω3-PUFAs, particularly EPA, in cardiovascular disease (CVD). REDUCE-IT demonstrated that high-dose EPA (4 g/day icosapent-ethyl) reduced a composite of clinical events by 25% in statin-treated patients with established CVD or diabetes and other cardiovascular risk factors. Outcome trials in similar statin-treated patients using DHA-containing high-dose ω3 formulations have not yet shown the benefits of EPA alone. However, there are data to show that high-dose ω3-PUFAs in patients with acute myocardial infarction had reduced left ventricular remodelling, non-infarct myocardial fibrosis, and systemic inflammation. ω3-polyunsaturated fatty acids, along with their metabolites, such as oxylipins and other lipid mediators, have complex effects on the cardiovascular system. Together they target free fatty acid receptors and peroxisome proliferator-activated receptors in various tissues to modulate inflammation and lipid metabolism. Here, we review these multifactorial mechanisms of ω3-PUFAs in view of recent clinical findings. These findings indicate physico-chemical and biological diversity among ω3-PUFAs that influence tissue distributions as well as disparate effects on membrane organization, rates of lipid oxidation, as well as various receptor-mediated signal transduction pathways and effects on gene expression.

The Short Overview on the Relevance of Fatty Acids for Human Cardiovascular Disorders

This review presents existing evidence of the influence of saturated and unsaturated fatty acids on cardiovascular diseases (CVD). Data are discussed regarding the roles of the most relevant fatty acids, such as myristic (C14:0), palmitic (C16:0), stearic (C18:0), palmitoleic (C16:1), oleic (C18:1), linoleic (C18:2), α-linolenic (C18:3, ω-3), γ-linolenic (C18:3, ω-6), arachidonic (C20:4), eicosapentaenoic (C20:5), docosahexaenoic (C22:6), and docosapentaenoic (C22:5) acid. The accumulated knowledge has expanded the understanding of the involvement of fatty acids in metabolic processes, thereby enabling the transition from basic exploratory studies to practical issues of application of these biomolecules to CVD treatment. In the future, these findings are expected to facilitate the interpretation and prognosis of changes in metabolic lipid aberrations in CVD.

Eicosapentaenoic acid attenuates renal lipotoxicity by restoring autophagic flux

Recently, we identified a novel mechanism of lipotoxicity in the kidney proximal tubular cells (PTECs); lipid overload stimulates macroautophagy/autophagy for the renovation of plasma and organelle membranes to maintain the integrity of the PTECs. However, this autophagic activation places a burden on the lysosomal system, leading to a downstream suppression of autophagy, which manifests as phospholipid accumulation and inadequate acidification in lysosomes. Here, we investigated whether pharmacological correction by eicosapentaenoic acid (EPA) supplementation could restore autophagic flux and alleviate renal lipotoxicity. EPA supplementation to high-fat diet (HFD)-fed mice reduced several hallmarks of lipotoxicity in the PTECs, such as phospholipid accumulation in the lysosome, mitochondrial dysfunction, inflammation, and fibrosis. In addition to improving the metabolic syndrome, EPA alleviated renal lipotoxicity via several mechanisms. EPA supplementation to HFD-fed mice or the isolated PTECs cultured in palmitic acid (PA) restored lysosomal function with significant improvements in the autophagic flux. The PA-induced redistribution of phospholipids from cellular membranes into lysosomes and the HFD-induced accumulation of SQSTM1/p62 (sequestosome 1), an autophagy substrate, during the temporal and genetic ablation of autophagy were significantly reduced by EPA, indicating that EPA attenuated the HFD-mediated increases in autophagy demand. Moreover, a fatty acid pulse-chase assay revealed that EPA promoted lipid droplet (LD) formation and transfer from LDs to the mitochondria for beta-oxidation. Noteworthy, the efficacy of EPA on lipotoxicity is autophagy-dependent and cell-intrinsic. In conclusion, EPA counteracts lipotoxicity in the proximal tubule by alleviating autophagic numbness, making it potentially suitable as a novel treatment for obesity-related kidney diseases.Abbreviations: 4-HNE: 4-hydroxy-2-nonenal; ACTB: actin beta; ADGRE1/F4/80: adhesion G protein-coupled receptor E1; ATG: autophagy-related; ATP: adenosine triphosphate; BODIPY: boron-dipyrromethene; BSA: bovine serum albumin; cKO: conditional knockout; CML: N-carboxymethyllysine; COL1A1: collagen type I alpha 1 chain; COX: cytochrome c oxidase; CTRL: control; DGAT: diacylglycerol O-acyltransferase; EPA: eicosapentaenoic acid; FA: fatty acid; FFA: free fatty acid; GFP: green fluorescent protein; HFD: high-fat diet; iKO: inducible knockout; IRI: ischemia-reperfusion injury; LAMP1: lysosomal-associated membrane protein 1; LD: lipid droplet; LRP2: low density lipoprotein receptor-related protein 2; MAP1LC3: microtubule-associated protein 1 light chain 3; MTORC1: mechanistic target of rapamycin kinase complex 1; OA: oleic acid; PAS: periodic-acid Schiff; PPAR: peroxisome proliferator activated receptor; PPARGC1/PGC1: peroxisome proliferator activated receptor, gamma, coactivator 1; PTEC: proximal tubular epithelial cell; ROS: reactive oxygen species; RPS6: ribosomal protein S6; SDH: succinate dehydrogenase complex; SFC/MS/MS: supercritical fluid chromatography triple quadrupole mass spectrometry; SQSTM1/p62: sequestosome 1; TFEB: transcription factor EB; TG: triglyceride; TUNEL: terminal deoxynucleotidyl transferase dUTP nick end labeling.

Emerging Mechanisms of Cardiovascular Protection for the Omega-3 Fatty Acid Eicosapentaenoic Acid

Patients with well-controlled LDL (low-density lipoprotein) levels still have residual cardiovascular risk associated with elevated triglycerides. Epidemiological studies have shown that elevated fasting triglyceride levels associate independently with incident cardiovascular events, and abundant recent human genetic data support the causality of TGRLs (triglyceride-rich lipoproteins) in atherothrombosis. Omega-3 fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), lower blood triglyceride concentrations but likely exert additional atheroprotective properties at higher doses. Omega-3 fatty acids modulate T-cell differentiation and give rise to various prostaglandins and specialized proresolving lipid mediators that promote resolution of tissue injury and inflammation. The REDUCE-IT (Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial) with an EPA-only formulation lowered a composite of cardiovascular events by 25% in patients with established cardiovascular disease or diabetes mellitus and other cardiovascular risk factors. This clinical benefit likely arises from multiple molecular mechanisms discussed in this review. Indeed, human plaques readily incorporate EPA, which may render them less likely to trigger clinical events. EPA and DHA differ in their effects on membrane structure, rates of lipid oxidation, inflammatory biomarkers, and endothelial function as well as tissue distributions. Trials that have evaluated DHA-containing high-dose omega-3 fatty acids have thus far not shown the benefits of EPA alone demonstrated in REDUCE-IT. This review will consider the mechanistic evidence that helps to understand the potential mechanisms of benefit of EPA.

Eicosapentaenoic Acid (EPA) Modulates Glucose Metabolism by Targeting AMP-Activated Protein Kinase (AMPK) Pathway

EPA, an omega-3 polyunsaturated fatty acid, exerts beneficial effects on human health. However, the molecular mechanisms underlying EPA function are poorly understood. The object was to illuminate molecular mechanism underlying EPA's role. Here, ¹H-NMR-based metabolic analysis showed enhanced branched-chain amino acids (BCAAs) and lactate following EPA treatment in skeletal muscle cells. EPA regulated mitochondrial oxygen consumption rate. Furthermore, EPA induced calcium/calmodulin-dependent protein kinase kinase (CaMKK) through the generation of intracellular calcium. This induced the phosphorylation of AMP-activated protein kinase (AMPK) and p38 mitogen-activated protein kinase (p38 MAPK) that led to glucose uptake, and the translocation of glucose transporter type 4 (GLUT4) in muscles. In conclusion, EPA exerts benign effects on glucose through the activation of AMPK-p38 MAPK signaling pathways in skeletal muscles.

An omega-3 fatty acid plasma index ≥4% prevents progression of coronary artery plaque in patients with coronary artery disease on statin treatment

BACKGROUND AND AIMS

Higher blood levels of the omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been associated with fewer cardiovascular events and lower mortality in prospective studies. Our aim was to determine a target level of EPA and DHA to prevent progression of coronary artery plaque.

METHODS

218 subjects with stable coronary artery disease on statins were randomized to high-dose EPA and DHA (3.36 g daily) or no omega-3 for 30 months. Coronary plaque volume was measured by coronary computed tomographic angiography. Plasma phospholipid levels of EPA, DHA and total fatty acids were measured by gas chromatography mass spectrometry. The omega-3 fatty acid index was calculated as EPA+DHA/total fatty acid.

RESULTS

Mean (SD) age was 62.9 (7.8) years; mean (SD) LDL-C level 78.6 (27.3) mg/dL and median triglyceride level 122 mg/dL. Subjects assigned to EPA and DHA had increased plasma EPA and DHA levels variably from 1.85% to 13.02%. Plasma omega-3 fatty acid index ≥4% prevented progression of fibrous, noncalcified, calcified and total plaque in nondiabetic subjects whereas those in the lowest quartile (<3.43%) had significant progression of fibrous, calcified and total plaque. No difference was observed in diabetic subjects.

CONCLUSIONS

EPA and DHA added to statins prevented coronary plaque progression in nondiabetic subjects with mean LDL-C <80 mg/dL, when an omega-3 index ≥4% was achieved. Low omega-3 index <3.43% identified nondiabetic subjects at risk of coronary plaque progression despite statin therapy. These findings highlight the importance of measuring plasma levels of omega-3 fatty acids early and at trial conclusion. Targeting an omega-3 index ≥4% maximizes cardiovascular benefit.

New Insights into Mechanisms of Action for Omega-3 Fatty Acids in Atherothrombotic Cardiovascular Disease

PURPOSE OF REVIEW

Treatment of hypercholesterolemia with statins results in significant reductions in cardiovascular risk; however, individuals with well-controlled low-density lipoprotein cholesterol (LDL-C) levels, but persistent high triglycerides (TG), remain at increased risk. Genetic and epidemiologic studies have shown that elevated fasting TG levels are associated with incident cardiovascular events. At effective doses, omega-3 fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), lower TG levels but may have additional atheroprotective properties compared to other TG-lowering therapies such as niacin and fibrates. The purpose of this review is to evaluate mechanisms related to the potential benefits of omega-3 fatty acids in atherothrombotic disease.

RECENT FINDINGS

Large randomized clinical trials are currently under way to test the cardiovascular benefits of omega-3 fatty acids at a pharmacologic dosage (4 g/day). A large randomized trial with a prescription EPA-only formulation was shown to reduce a composite of cardiovascular events by 25% in statin-treated patients with established cardiovascular disease or diabetes and other CV risk factors. EPA and DHA have distinct tissue distributions as well as disparate effects on membrane structure and lipid dynamics, rates of lipid oxidation, and signal transduction pathways. Compared to other TG-lowering therapies, EPA has been found to inhibit cholesterol crystal formation, inflammation, and oxidative modification of atherogenic lipoprotein particles. The anti-inflammatory and endothelial benefits of EPA are enhanced in combination with a statin. Omega-3 fatty acids like EPA only at a pharmacologic dose reduce fasting TG and interfere with mechanisms of atherosclerosis that results in reduced cardiovascular events. Additional mechanistic trials will provide further insights into their role in reducing cardiovascular risk in subjects with well-managed LDL-C but elevated TG levels.

Role of Borage Seed Oil and Fish Oil with or without Turmeric and Alpha- Tocopherol in Prevention of Cardiovascular Disease and Fatty Liver in Rats

The aim of the present research was to Study the prevention of dyslipidemia, oxidative stress, inflammation and fatty liver as risk factors for cardiovascular disease via intervention by borage oil (B) and fish oil (F) with or without turmeric (T) and alpha-tocopherols (TC). Fatty acids were assessed in both oils while curcuminoids were determined in turmeric. Rats were divided into; first group fed on balanced diet and designated as normal control (NC), second fed on dyslipidemic and steatohepatitis (DS) inducer diet which represented the DS control group and groups 3-6 fed on DS inducer diet with daily oral administration of B, B+T+TC, F and F+T+TC; respectively for 5 weeks. Liver fat and plasma lipid profile, oxidative stress and inflammatory biomarker and liver and heart histopathology were assessed. Results showed gamma linolenic to be 21.01% in B. F contained eicosapentaenoic as 22.768% and docosahexaenoic acid as 13.574%.Total curcuminoids were 4.63 mg/g turmeric. The DS control group showed significant dyslipidemia, elevated malondialdehyde (MDA), tumor necrosis factor-alpha and liver fat with significant reduction in total antioxidant capacity (TAC) compared to NC. The different treatments produced significant improvement in all the parameters and histopathology. F was superior to B in ameliorating liver histopathological changes while B was more efficient in elevating TAC. B was more promising in improving lipid profile and liver fat compared to B + T + TC, while the latter was superior in improving MDA and liver histopathology. Fish oil was more efficient than F+TC+T except for TAC and high density lipoprotein cholesterol which were more improved on addition of TC and T. Conclusion: Borage and fish oil with or without antioxidants protect from cardiovascular and fatty liver diseases with variable degrees.

Eicosapentaenoic acid improves endothelial function and nitric oxide bioavailability in a manner that is enhanced in combination with a statin

The endothelium exerts many vasoprotective effects that are largely mediated by release of nitric oxide (NO). Endothelial dysfunction represents an early but reversible step in atherosclerosis and is characterized by a reduction in the bioavailability of NO. Previous studies have shown that eicosapentaenoic acid (EPA), an omega-3 fatty acid (O3FA), and statins individually improve endothelial cell function, but their effects in combination have not been tested. Through a series of in vitro experiments, this study evaluated the effects of a combined treatment of EPA and the active metabolite of atorvastatin (ATM) on endothelial cell function under conditions of oxidative stress. Specifically, the comparative and time-dependent effects of these agents on endothelial dysfunction were examined by measuring the levels of NO and peroxynitrite (ONOO^-) released from human umbilical vein endothelial cells (HUVECs). The data suggest that combined treatment with EPA and ATM is beneficial to endothelial function and was unique to EPA and ATM since similar improvements could not be recapitulated by substituting another O3FA docosahexaenoic acid (DHA) or other TG-lowering agents such as fenofibrate, niacin, or gemfibrozil. Comparable beneficial effects were observed when HUVECs were pretreated with EPA and ATM before exposure to oxidative stress. Interestingly, the kinetics of EPA-based protection of endothelial function in response to oxidation were found to be significantly different than those of DHA. Lastly, the beneficial effects on endothelial function generated by combined treatment of EPA and ATM were reproduced when this study was expanded to an ex vivo model utilizing rat glomerular endothelial cells. Taken together, these findings suggest that a combined treatment of EPA and ATM can inhibit endothelial dysfunction that occurs in response to conditions such as hyperglycemia, oxidative stress, and dyslipidemia.

Eicosapentaenoic acid and docosahexaenoic acid have distinct membrane locations and lipid interactions as determined by X-ray diffraction

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) differentially influence lipid oxidation, signal transduction, fluidity, and cholesterol domain formation, potentially due in part to distinct membrane interactions. We used small angle X-ray diffraction to evaluate the EPA and DHA effects on membrane structure. Membrane vesicles composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and cholesterol (C) (0.3C:POPC mole ratio) were prepared and treated with vehicle, EPA, or DHA (1:10 mol ratio to POPC). Electron density profiles generated from the diffraction data showed that EPA increased membrane hydrocarbon core electron density over a broad area, up to ± 20 Å from the membrane center, indicating an energetically favorable extended orientation for EPA likely stabilized by van der Waals interactions. By contrast, DHA increased electron density in the phospholipid head group region starting at ± 12 Å from the membrane center, presumably due to DHA-surface interactions, with coincident reduction in electron density in the membrane hydrocarbon core centered ± 7-9 Å from the membrane center. The membrane width (d-space) decreased by 5 Å in the presence of vehicle as the temperature increased from 10 °C to 30 °C due to increased acyl chain trans-gauche isomerizations, which was unaffected by addition of EPA or DHA. The influence of DHA on membrane structure was modulated by temperature changes while the interactions of EPA were unaffected. The contrasting EPA and DHA effects on membrane structure indicate distinct molecular locations and orientations that may contribute to observed differences in biological activity.

Eicosapentaenoic acid inhibits oxidation of high density lipoprotein particles in a manner distinct from docosahexaenoic acid

The omega-3 fatty acid eicosapentaenoic acid (EPA) reduces oxidation of ApoB-containing particles in vitro and in patients with hypertriglyceridemia. EPA may produce these effects through a potent antioxidant mechanism, which may facilitate LDL clearance and slow plaque progression. We hypothesize that EPA antioxidant effects may extend to ApoA-containing particles like HDL, potentially preserving certain atheroprotective functions. HDL was isolated from human plasma and incubated at 37 °C in the absence (vehicle) or presence of EPA and/or DHA; 5.0 or 10.0 μM each. Samples were then subjected to copper-induced oxidation (10 μM). HDL oxidation was inhibited similarly by EPA and DHA up to 1 h. EPA (10 μM) maintained significant HDL oxidation inhibition of 89% (0.622 ± 0.066 μM MDA; p < .001) at 4 h, with continued inhibition of 64% at 14 h, vs. vehicle (5.65 ± 0.06 to 2.01 ± 0.10 μM MDA; p < .001). Conversely, DHA (10 μM) antioxidant benefit was lost by 4 h. At a lower concentration (5 μM), EPA antioxidant activity remained at 81% (5.53 ± 0.15 to 1.03 ± 0.10 μM MDA; p < .001) at 6 h, while DHA lost all antioxidant activity by 4 h. The antioxidant activity of EPA was preserved when combined with an equimolar concentration of DHA (5 μM each). EPA pretreatment prevented HDL oxidation in a dose-dependent manner that was preserved over time. These results suggest unique lipophilic and electron stabilization properties for EPA as compared to DHA with respect to inhibition of HDL oxidation. These antioxidant effects of EPA may enhance certain atheroprotective functions for HDL.

Review of Cardiometabolic Effects of Prescription Omega-3 Fatty Acids

PURPOSE OF REVIEW

Populations with significant dietary fish intake tend to have lower cardiovascular (CV) risk and demonstrable physiologic differences including lower lipid/lipoprotein levels and other direct and indirect effects on the arterial wall and inhibiting factors that promote atherosclerosis. Treatment with high doses of pharmacologic-grade omega-3 fatty acid (n-3FA) supplements achieves significant reductions in triglycerides (TG), non-high-density lipoprotein- (non-HDL-) and TG-rich lipoprotein- (TRL-) cholesterol levels. n-3FA supplements have significant effects on markers of atherosclerosis risk including endothelial function, low-density lipoprotein (LDL) oxidation, cellular and humoral markers of inflammation, hemodynamic factors, and plaque stabilization. This review summarizes the lipid and cardiometabolic effects of prescription-grade n-3FAs and will discuss clinical trials, national/organizational guidelines, and expert opinion on the impact of supplemental n-3FAs on CV health and disease.

RECENT FINDINGS

Clinical trial evidence supports use of n-3FAs in individuals with established atherosclerotic cardiovascular disease (ASCVD), but the data either does not support or is lacking for other types of cardiometabolic risk including prevention of stroke, treatment in patients with heart failure, diabetes mellitus and prediabetes, and for primary prevention in the general population. Despite inconsistent findings to support widespread benefit, there is persistent population-wide enthusiasm for n-3FA as a dietary supplement for its cardiometabolic benefits. Fortunately, there are ongoing clinical trials to assess whether the lipid/lipoprotein benefits may be extended to other at-risk populations and whether lower-dose therapy may provide background benefit for primary prevention of ASCVD.

Eicosapentaenoic Acid Inhibits Oxidation of ApoB-containing Lipoprotein Particles of Different Size In Vitro When Administered Alone or in Combination With Atorvastatin Active Metabolite Compared With Other Triglyceride-lowering Agents

Eicosapentaenoic acid (EPA) is a triglyceride-lowering agent that reduces circulating levels of the apolipoprotein B (apoB)-containing lipoprotein particles small dense low-density lipoprotein (sdLDL), very–low-density lipoprotein (VLDL), and oxidized low-density lipoprotein (LDL). These benefits may result from the direct antioxidant effects of EPA. To investigate this potential mechanism, these particles were isolated from human plasma, preincubated with EPA in the absence or presence of atorvastatin (active) metabolite, and subjected to copper-initiated oxidation. Lipid oxidation was measured as a function of thiobarbituric acid reactive substances formation. EPA inhibited sdLDL (IC₅₀ ∼2.0 μM) and LDL oxidation (IC₅₀ ∼2.5 μM) in a dose-dependent manner. Greater antioxidant potency was observed for EPA in VLDL. EPA inhibition was enhanced when combined with atorvastatin metabolite at low equimolar concentrations. Other triglyceride-lowering agents (fenofibrate, niacin, and gemfibrozil) and vitamin E did not significantly affect sdLDL, LDL, or VLDL oxidation compared with vehicle-treated controls. Docosahexaenoic acid was also found to inhibit oxidation in these particles but over a shorter time period than EPA. These data support recent clinical findings and suggest that EPA has direct antioxidant benefits in various apoB-containing subfractions that are more pronounced than those of other triglyceride-lowering agents and docosahexaenoic acid.

Eicosapentaenoic Acid as a Potential Therapeutic Approach to Reduce Cardiovascular Risk in Patients with End-Stage Renal Disease on Hemodialysis: A Review

Background

Patients with end-stage renal disease on hemodialysis have excess cardiovascular disease (CVD) burden with substantially increased CV event rates compared with the general population.

Summary

Traditional interventions that, according to standard clinical guidelines, reduce CV risk such as antihypertensive therapy, diet, exercise, and statins are not similarly effective in the hemodialysis population. This raises the question of whether additional risk factors, such as enhanced inflammation and oxidative stress, may drive the increased CVD burden in hemodialysis patients. Eicosapentaenoic acid (EPA), an omega-3 polyunsaturated fatty acid, is incorporated into the atherosclerotic plaque as well as membrane phospholipid bilayers and produces beneficial effects on inflammatory and oxidative mechanisms involved in atherosclerotic plaque formation and progression. EPA levels and the ratio of EPA to the omega-6 polyunsaturated fatty acid arachidonic acid (AA) are reduced in hemodialysis patients. Serum EPA levels have been inversely correlated with proinflammatory cytokines, and the EPA/AA ratio has been inversely associated with CV events in hemodialysis cohorts. Three recent studies involving over 800 hemodialysis patients and follow-up of 2-3 years suggest that EPA therapy may improve clinical outcomes in this patient population as evidenced by significant reductions in cardiovascular mortality, all-cause mortality, and/or CV events.

Key Messages

Further studies with high-purity EPA are warranted in patients on hemodialysis, especially given the fact that other interventions including antihypertensives, diet, exercise, and statins have not provided meaningful benefit.

Prescription omega-3 fatty acid products containing highly purified eicosapentaenoic acid (EPA)

The omega-3 fatty acid eicosapentaenoic acid (EPA) has multiple actions potentially conferring cardiovascular benefit, including lowering serum triglyceride (TG) and non-high-density lipoprotein cholesterol (non-HDL-C) levels and potentially reducing key steps in atherogenesis. Dietary supplements are a common source of omega-3 fatty acids in the US, but virtually all contain docosahexaenoic acid (DHA) in addition to EPA, and lipid effects differ between DHA and EPA. Contrary to popular belief, no over-the-counter omega-3 products are available in the US, only prescription products and dietary supplements. Among the US prescription omega-3 products, only one contains EPA exclusively (Vascepa); another closely related prescription omega-3 product also contains highly purified EPA, but is approved only in Japan and is provided in different capsule sizes. These high-purity EPA products do not raise low-density lipoprotein cholesterol (LDL-C) levels, even in patients with TG levels >500 mg/dL, in contrast to the increase in LDL-C levels with prescription omega-3 products that also contain DHA. The Japanese prescription EPA product was shown to significantly reduce major coronary events in hypercholesterolemic patients when added to statin therapy in the Japan EPA Lipid Intervention Study (JELIS). The effects of Vascepa on cardiovascular outcomes are being investigated in statin-treated patients with high TG levels in the Reduction of Cardiovascular Events With EPA-Intervention Trial (REDUCE-IT).

Hot Water Extract of Leather Carp (Cyprinus carpio nudus) Improves Exercise Performance in Mice

The hot water extract of leather carp (Cyprinus carpio nudus) has been used as a nourishing tonic soup and as an aid for recovery from physical fatigue. In this study, we investigated the effect of leather carp extract on exercise performance in mice. Swimming endurance and forelimb grip strength were assessed following oral administration of the extract (once per day for 7 days) at a dose of 0.5 mg/10 μL/g body weight. After 7 days, mice given the leather carp extract had significantly greater swimming endurance [105±18 s (P<0.05); 52% longer than day 0] and forelimb grip strength [1.18±0.05 Newton (P<0.01); 17% greater than day 0]. The extract increased muscle mass, but had little effect on body weight. Following the swimming exercise, blood glucose, glutathione peroxidase, and superoxide dismutase levels in extract-fed mice were significantly higher (145%, 131%, and 106%, respectively) than in the saline control group. Blood levels of high-density lipoprotein cholesterol were also significantly increased (128%) in mice given the extract compared to the controls. These results suggest that leather carp extract can improve physical exercise performance and prevent oxidative stress caused by exhaustive workouts.