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

Efficacy and Safety of Omega-3 Fatty Acids in the Prevention of Cardiovascular Disease: A Systematic Review and Meta-analysis

BACKGROUND

It is widely accepted that omega-3 fatty acids are beneficial in the prevention of cardiovascular disease, but many large randomized controlled trial studies and meta-analyses have come to different conclusions. The evidence for omega-3 fatty acids supplementation to prevent cardiovascular disease remains insufficient. We conducted a systematic review and meta-analysis to evaluate the efficacy and safety of several types of omega-3 fatty acids supplements.

METHODS

We comprehensively searched the online database and found 15 RCTs. The primary efficacy outcomes included major cardiovascular events, myocardial infarction, heart failure, atrial fibrillation, stroke, cardiovascular death, and all-cause death. The safety endpoints included gastrointestinal problems, bleeding-related disorders, and cancer. Subgroup analysis was conducted according to the main characteristics of the population, and the dose-response relationship of omega-3 fatty acids was evaluated by meta-regression. All results were calculated by the random effect model. Statistical heterogeneity was assessed using chi-square tests and quantified using I-square statistics.

RESULTS

The incidence of major cardiovascular events (RR 0.95, 95%CI 0.91 to 0.99, P = 0.026), myocardial infarction (RR 0.90, 95%CI 0.83 to 0.98; P = 0.021), and cardiovascular death (RR 0.94, 95%CI 0.88 to 0.99; P = 0.028) was reduced in the omega-3 fatty acid group compared with the control group. An increased risk of atrial fibrillation (RR 1.25, 95%CI 1.10 to 1.41; P = 0.000) was observed in patients in the omega-3 fatty acid group. No statistical differences were observed between the two groups in heart failure, stroke, and all-cause death. For safety endpoints, there were no statistically significant differences between the two groups in gastrointestinal problems, bleeding-related disorders, and cancer. Subgroup analysis showed that the cardiovascular benefit of omega-3 fatty acids was primarily attributable to the prescription of EPA ethyl ester. Omega-3 fatty acids may reduce the risk of major cardiovascular events in patients with cardiovascular disease or risk factors, and reduce the risk of myocardial infarction in patients without cardiovascular disease; however, they may increase the risk of stroke in patients with myocardial infarction. In addition, prescription omega-3 acid ethyl ester has a good safety profile, and prescription EPA ethyl ester has a high risk of bleeding.

CONCLUSION

Moderate evidence showed that the use of omega-3 fatty acids may reduce the risk of major cardiovascular events, myocardial infarction, and cardiovascular death. Compared to other types of omega-3 fatty acids supplements, we support the use of prescription EPA ethyl ester formulations for the prevention of cardiovascular disease, but the potential risk of atrial fibrillation and bleeding cannot be ignored. It is important to note that omega-3 fatty acids should be applied with caution in patients with previous myocardial infarction, which may increase the risk of stroke. Finally, omega-3 fatty acids are relatively safe and in general do not increase gastrointestinal problems, bleeding-related disorders, or cancer, but attention needs to be paid to the risk of bleeding with prescription EPA ethyl ester formulations.

Eicosapentaenoic Acid Improves Endothelial Nitric Oxide Bioavailability Via Changes in Protein Expression During Inflammation

BACKGROUND

Endothelial cell (EC) dysfunction involves reduced nitric oxide (NO) bioavailability due to NO synthase uncoupling linked to increased oxidation and reduced cofactor availability. Loss of endothelial function and NO bioavailability are associated with inflammation, including leukocyte activation. Eicosapentaenoic acid (EPA) administered as icosapent ethyl reduced cardiovascular events in REDUCE-IT (Reduction of Cardiovascular Events With Icosapent Ethyl-Intervention Trial) in relation to on-treatment EPA blood levels. The mechanisms of cardiovascular protection for EPA remain incompletely elucidated but likely involve direct effects on the endothelium.

METHODS AND RESULTS

In this study, human ECs were treated with EPA and challenged with the cytokine IL-6 (interleukin-6). Proinflammatory responses in the ECs were confirmed by ELISA capture of sICAM-1 (soluble intercellular adhesion molecule-1) and TNF-α (tumor necrosis factor-α). Global protein expression was determined using liquid chromatography-mass spectrometry tandem mass tag. Release kinetics of NO and peroxynitrite were monitored using porphyrinic nanosensors. IL-6 challenge induced proinflammatory responses from the ECs as evidenced by increased release of sICAM-1 and TNF-α, which correlated with a loss of NO bioavailability. ECs pretreated with EPA modulated expression of 327 proteins by >1-fold (P<0.05), compared with IL-6 alone. EPA augmented expression of proteins involved in NO production, including heme oxygenase-1 and dimethylarginine dimethylaminohydrolase-1, and 34 proteins annotated as associated with neutrophil degranulation. EPA reversed the endothelial NO synthase uncoupling induced by IL-6 as evidenced by an increased [NO]/[peroxynitrite] release ratio (P<0.05).

CONCLUSIONS

These direct actions of EPA on EC functions during inflammation may contribute to its distinct cardiovascular benefits.

Impact of dietary n-6/n-3 fatty acid ratio of atherosclerosis risk: A review

Atherosclerosis is a causative factor associated with cardiovascular disease (CVD). Over the past few decades, extensive research has been carried out on the relationship between the n-6/n-3 fatty acid ratio of ingested lipids and the progression of atherosclerosis. However, there are still many uncertainties regarding the precise nature of this relationship, which has led to challenges in providing sound dietary advice to the general public. There is therefore a pressing need to review our current understanding of the relationship between the dietary n-6/n-3 fatty acid ratio and atherosclerosis, and to summarize the underlying factors contributing to the current uncertainties. Initially, this article reviews the association between the n-6/n-3 fatty acid ratio and CVDs in different countries. A summary of the current understanding of the molecular mechanisms of n-6/n-3 fatty acid ratio on atherosclerosis is then given, including inflammatory responses, lipid metabolism, low-density lipoprotein cholesterol oxidation, and vascular function. Possible reasons behind the current controversies on the relationship between the n-6/n-3 fatty acid ratio and atherosclerosis are then provided, including the precise molecular structures of the fatty acids, diet-gene interactions, the role of fat-soluble phytochemicals, and the impact of other nutritional factors. An important objective of this article is to highlight areas where further research is needed to clarify the role of n-6/n-3 fatty acid ratio on atherosclerosis.

Omega-3 fatty acids for cardiovascular event lowering

Low-density lipoprotein cholesterol (LDL-C) is the main target for therapeutics aimed at reducing the risk of atherosclerotic cardiovascular disease (ASCVD) and downstream cardiovascular (CV) events. However, multiple studies have demonstrated that high-risk patient populations harbour residual risk despite effective LDL-C lowering. While data support the causal relationship between triglycerides and ASCVD risk, triglyceride-lowering therapies such as omega-3 fatty acids have shown mixed results in CV outcomes trials. Notably, icosapent ethyl, a purified formulation of eicosapentaenoic acid (EPA), has garnered compelling evidence in lowering residual CV risk in patients with hypertriglyceridaemia and treated with statins. In this review, we summarize studies that have investigated omega-3-fatty acids for CV event lowering and discuss the clinical implementation of these agents based on trial data and guidelines.

Omega-3 fatty acids in primary and secondary prevention of cardiovascular diseases

Even with substantial progress in primary and secondary prevention, cardiovascular disease (CVD) persists as a major cause of mortality and morbidity globally. Omega-3 polyunsaturated fatty acids (Ω-3 PUFAs) have gained considerable attention for their ability to improve CV health and prognosis. Metanalyses of randomized controlled trials have demonstrated Ω-3 PUFAs' positive impact on CVD outcomes for both primary and secondary prevention endpoints. Marine Ω-3 PUFAs also improve CVD risk factors including blood pressure, lipids, and inflammation; however, many physicians do not recommend Ω-3 PUFAs, largely due to inconsistent results in randomized trials. In this comprehensive review article, we evaluate both historic and current data concerning primary and secondary prevention of CVD with use of Ω-3 PUFAs, delve into the potential causes for the varied results, and examine the most current recommendations on the usage of Ω-3 PUFAs.

5,6-diHETE lactone (EPA-L) mediates hypertensive microvascular dilation by activating the endothelial GPR-PLC-IP3 signaling pathway

Endothelial microvascular dysfunction affects multi-organ pathologic processes that contribute to increased vascular tone and is at the base of impaired metabolic and cardiovascular diseases. The vascular dilation impaired by nitric oxide (NO) deficiency in such dysfunctional endothelium is often balanced by endothelial-derived hyperpolarizing factors (EDHFs), which play a critical role in managing vascular tone. Our latest research has uncovered a new group of lactone oxylipins produced in the polyunsaturated fatty acids (PUFAs) CYP450 epoxygenase pathway, significantly affecting vascular dilation. The lactone oxylipin, derived from arachidonic acid (5,6-diHET lactone, AA-L), has been previously shown to facilitate vasodilation dependent on the endothelium in isolated human microvessels. The administration of the lactone oxylipin derived from eicosapentaenoic acid (5,6-diHETE lactone, EPA-L) to hypertensive rats demonstrated a significant decrease in blood pressure and improvement in the relaxation of microvessels. However, the molecular signaling processes that underlie these observations were not fully understood. The current study delineates the molecular pathways through which EPA-L promotes endothelium-dependent vascular dilation. In microvessels from hypertensive individuals, it was found that EPA-L mediates endothelium-dependent vasodilation while the signaling pathway was not dependent on NO. In vitro studies on human endothelial cells showed that the hyperpolarization mediated by EPA-L relies on G-protein-coupled receptor (GPR)-phospholipase C (PLC)-IP3 signaling that further activates calcium-dependent potassium flux. The pathway was confirmed using a range of inhibitors and cells overexpressing GPR40, where a specific antagonist reduced the calcium levels and outward currents induced by EPA-L. The downstream AKT and endothelial NO synthase (eNOS) phosphorylations were non-significant. These findings show that the GPR-PLC-IP3 pathway is a key mediator in the EPA-L-triggered vasodilation of arterioles. Therefore, EPA-L is identified as a significant lactone-based PUFA metabolite that contributes to endothelial and vascular health.

Associations of Plasma Omega-3 Fatty Acids With Progression and Survival in Pulmonary Fibrosis

BACKGROUND

Preclinical experiments suggest protective effects of omega-3 fatty acids and their metabolites in lung injury and fibrosis. Whether higher intake of omega-3 fatty acids is associated with disease progression and survival in humans with pulmonary fibrosis is unknown.

RESEARCH QUESTION

What are the associations of plasma omega-3 fatty acid levels (a validated marker of omega-3 nutritional intake) with disease progression and transplant-free survival in pulmonary fibrosis?

STUDY DESIGN AND METHODS

Omega-3 fatty acid levels were measured from plasma samples of patients with clinically diagnosed pulmonary fibrosis from the Pulmonary Fibrosis Foundation Patient Registry (n = 150), University of Virginia (n = 58), and University of Chicago (n = 101) cohorts. The N-3 index (docosahexaenoic acid + eicosapentaenoic acid) was the primary exposure variable of interest. Linear-mixed effects models with random intercept and slope were used to examine associations of plasma omega-3 fatty acid levels with changes in FVC and diffusing capacity for carbon monoxide over a period of 12 months. Cox proportional hazards models were used to examine transplant-free survival. Stratified analyses by telomere length were performed in the University of Chicago cohort.

RESULTS

Most of the cohort were patients with idiopathic pulmonary fibrosis (88%) and male patients (74%). One-unit increment in log-transformed N-3 index plasma level was associated with a change in diffusing capacity for carbon monoxide of 1.43 mL/min/mm Hg per 12 months (95% CI, 0.46-2.41) and a hazard ratio for transplant-free survival of 0.44 (95% CI, 0.24-0.83). Cardiovascular disease history, smoking, and antifibrotic usage did not significantly modify associations. Omega-3 fatty acid levels were not significantly associated with changes in FVC. Higher eicosapentaenoic acid plasma levels were associated with longer transplant-free survival among University of Chicago participants with shorter telomere length (P value for interaction = .02).

INTERPRETATION

Further research is needed to investigate underlying biological mechanisms and whether omega-3 fatty acids are a potential disease-modifying therapy.

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.

Relationship of phytochemicals and antioxidant activities in Gymnema inodorum leaf extracts

Gynmena inodorum (GI) is a green leafy vegetable used in the Northern Thai cuisine which has antioxidant activities and may be applicable for preventing oxidative stress and aging-related disease. However, understanding the relationship between GI phytonutrients and their antioxidant properties has been unclear. The aims of this study were to identify the GI leaf phytochemicals and to study their antioxidant activities. A chromatogram of LC-ESI-MS/QTOF-MS showed that the GI leaves were potentially composed of phenolics, quinic acids, flavonoids, and triterpenoid saponins. This study was able to authenticate quercetin, kaempferol, and triterpenoid GIA1 in the samples. The GI materials with high contents of phenolics, flavonoids, quercetin, and kaempferol showed significant relation to antioxidation and protection in endothelial cell death suppressed by reactive nitrogen species. Meanwhile, triterpenoids had a low antioxidant impact. Ultimately, GI leaves with high phenolic compounds are a promising raw material to develop as an antioxidant functional food.

Study of the spread of medicinal herbs use among patients suffering from chronic diseases in Iraq

OBJECTIVE

Aim: To assess the prevalence of medicinal plants, use among Iraqi patients with chronic disease and compare it with another study in same or different countries.

PATIENTS AND METHODS

Materials and Methods: A randomized Internet and social media questionnaire was used. In this cross-sectional study, peoples with chronic diseases from different age group were recruited. Participants had an internet questionnaire to answer. This questionnaire embraced age, gender, occupation, marital status, education level and some lifestyle details as demographic data, a large proportion of the questionnaire was related to herbs, both prescribed and OTC ones.

RESULTS

Results: Gender distribution: about 70% of patients were female and 30% male. Education level: uneducated - 35%, primary school - 30%, secondary school - 25%, academic - 10%. Place of residence: 30% lived in urban and 70% in rural areas. Diseases distribution: 30% hypertension, 20% diabetes, 10% asthma, 10% migraine, 15% hyperlipidemia and 15% rheumatoid arthritis. Medicinal plants: 10% green tea, 5%fish oil, 15% anise 25% castor oil and 15% spirulina.

CONCLUSION

Conclusions: The study reported a high prevalence of medicinal herbs use among patients with chronic disease in Iraq. Several factors (rural residence, education, age, multiple chronic conditions and low quality of life) associated with medicinal herbs use. This knowledge will help policy makers and health care providers for decision making on the safe use of herbal medicine.

Icosapent ethyl (VASCEPA®) as treatment for post-acute sequelae of SARS CoV-2 (PASC) vaccine induced injury and infection

OBJECTIVES

As the COVID-19 pandemic continues, a prolonged post-infectious syndrome or "long COVID" has been reported. This is a multi-organ post viral syndrome that persists well after infection. Currently, there is no available treatment. Emerging evidence credits this "long COVID" syndrome to ongoing inflammatory response following resolution of symptoms during infection. An omega-three fatty acid derivative used in the treatment of hypertriglyceridemia, Icosapent Ethyl (IPE, VASCEPA®/Epadel®), was previously shown to reduce cardiovascular risk, likely via immunomodulatory effects. This study aims to evaluate the effectiveness of Icosapent Ethyl.

METHODS

Following previous publications in treatment of severe acute COVID-19, we analyze two case studies of adults treated with Icosapent Ethyl.

RESULTS

After experiencing the symptoms of Long Covid, both individuals analyzed across two case studies experiences a resolution of symptoms after treatment with Icosapent Ethyl.

CONCLUSION

After review and analysis we conclude that Icosapent Ethyl may have been a determining factor in Long COVID symptom resolution and should be studied further.

The Effects of Omega 3 and Omega 6 Fatty Acids on Glucose Metabolism: An Updated Review

Massive changes have occurred in our diet. A growing consumption of vegetal oils rich in omega-6 (ω-6) and a depletion of omega-3 (ω-3) fatty acids (FAs) in our food has led to an imbalance between ω-3 and ω-6. In particular, eicosapentaenoic (EPA)/arachidonic acid (AA) ratio seems to be an indicator of this derangement, whose reduction is associated to the development of metabolic diseases, such as diabetes mellitus. Our aim was therefore to investigate the literature on the effects of ω-3 and ω-6 FAs on glucose metabolism. We discussed emerging evidence from pre-clinical studies and from clinical trials. Notably, conflicting results emerged. Source of ω-3, sample size, ethnicity, study duration and food cooking method may be responsible for the lack of univocal results. High EPA/AA ratio seems to be a promising indicator of better glycemic control and reduced inflammation. On the other hand, linoleic acid (LA) appears to be also associated to a minor incidence of type 2 diabetes mellitus, although it is still not clear if the outcome is related to a reduced production of AA or to its intrinsic effect. More data derived from multicenter, prospective randomized clinical trials are needed.

Eicosapentaenoic acid (EPA) reduces pulmonary endothelial dysfunction and inflammation due to changes in protein expression during exposure to particulate matter air pollution

AIMS

Inhalation of air pollution small particle matter (PM) is a leading cause of cardiovascular (CV) disease. Exposure to PMs causes endothelial cell (EC) dysfunction as evidenced by nitric oxide (NO) synthase uncoupling, vasoconstriction and inflammation. Eicosapentaenoic acid (EPA) has been shown to mitigate PM-induced adverse cardiac changes in patients receiving omega-3 fatty acid supplementation. We set out to determine the pro-inflammatory effects of multiple PMs (urban and fine) on pulmonary EC NO bioavailability and protein expression, and whether EPA restores EC function under these conditions.

METHODS AND RESULTS

We pretreated pulmonary ECs with EPA and then exposed them to urban or fine air pollution PMs. LC/MS-based proteomic analysis to assess relative expression levels. Expression of adhesion molecules was measured by immunochemistry. The ratio of NO to peroxynitrite (ONOO-) release, an indication of eNOS coupling, was measured using porphyrinic nanosensors following calcium stimulation. Urban/fine PMs also modulated 9/12 and 13/36 proteins, respectively, linked to platelet and neutrophil degranulation pathways and caused > 50% (p < 0.001) decrease in the stimulated NO/ONOO- release ratio. EPA treatment altered expression of proteins involved in these inflammatory pathways, including a decrease in peroxiredoxin-5 and an increase in superoxide dismutase-1. EPA also increased expression of heme oxygenase-1 (HMOX1), a cytoprotective protein, by 2.1-fold (p = 0.024). EPA reduced elevations in sICAM-1 levels by 22% (p < 0.01) and improved the NO/ONOO- release ratio by > 35% (p < 0.05).

CONCLUSION

These cellular changes may contribute to anti-inflammatory, cytoprotective and lipid changes associated with EPA treatment during air pollution exposure.

Growth State-Dependent Activation of eNOS in Response to DHA: Involvement of p38 MAPK

Our laboratory previously reported that docosahexaenoic acid (DHA) differentially activates p38 mitogen-activated protein kinase (MAPK) in growing and quiescent human endothelial cells, which represent the dysfunctional and healthy states in vivo, respectively. Since endothelial nitric oxide synthase (eNOS) activity differs between healthy and dysfunctional endothelial cells, and p38 MAPK reportedly regulates both the activity and expression of eNOS, we hypothesized that the beneficial actions of DHA on endothelial cells are due to eNOS activation by p38 MAPK. The contribution of mitogen- and stress-activated protein kinase (MSK), a p38 MAPK substrate, was also investigated. Growing and quiescent EA.hy926 cells, prepared on Matrigel^®-coated plates, were incubated with inhibitors of p38MAPK or MSK before adding DHA. eNOS phosphorylation and levels were quantified by Western blotting. Treatment with 20 µM DHA activated eNOS in both growth states whereas 125 µM DHA suppressed eNOS activation in growing cells. Quiescent cells had higher basal levels of eNOS than growing cells, while 125 µM DHA decreased eNOS levels in both growth states. p38 MAPK inhibition enhanced eNOS activation in quiescent cells but suppressed it in growing cells. Interestingly, 125 µM DHA counteracted these effects of p38 MAPK inhibition in both growth states. MSK was required for eNOS activation in both growth states, but it only mediated eNOS activation by DHA in quiescent cells. MSK thus affects eNOS via a pathway independent of p38MAPK. Quiescent cells were also more resistant to the apoptosis-inducing effect of 125 µM DHA compared to growing cells. The growth state-dependent regulation of p38MAPK and eNOS by DHA provides novel insight into the molecular mechanisms by which DHA influences endothelial cell function.

Fish oil supplementation protects against protein undernutrition-induced testicular and ovarian biochemical alterations in rats

Proteins are required for biological functions and their inadequacy might impair the growth and development of the reproductive system. The study investigated the effects of fish oil (FO) supplementation on low-protein diet-induced alterations in male and female reproductive organs. Male and female rats were assigned randomly to four groups respectively. The NPD rats had five rats per group and were given 16% casein diet while the LPD rats had eight rats per group and received 5% casein diet. After the 8th week, FO was administered for 3 weeks via oral gavage at a concentration of 400mg Kg^-1 after which the rats were sacrificed and testes and ovaries were excised. LPD-fed rats showed lower body weights for both genders. In LPD-fed rats, NO was significantly increased while GSH, vitamins C and E levels, the activities of CAT (except in ovaries), and GST were significantly reduced in both tissues. The activities of SOD and GPx were only reduced in the testes including sperm count, motility, and increase deformed sperm cells. Testosterone and progesterone levels were also reduced and lipid homeostasis was disrupted in the plasma of LPD-fed rats. FO supplementation reduces the NO, CHOL, TG, LDL (in females), and VLDL but significantly improves HDL (in females), testosterone, and progesterone levels, sperm count, motility, and morphology. The antioxidant status of both tissues also increased significantly in LPD-fed rats. Conclusively, FO might be effective in improving testicular and ovarian functions and for the maintenance of plasma lipid homeostasis in LPD-fed rats.

Effects of Combining Docosahexaenoic Acid and Eicosapentaenoic Acid with Sesame Lignan on Vascular Endothelial Function

Vascular endothelial cells produce vasoactive substances, such as nitric oxide (NO), to regulate vascular relaxation and contraction. Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) enhance NO production in endothelial cells, and sesamin, a sesame lignan contained in sesame seeds, also promotes NO production. This study examined DHA, EPA, and sesamin's combined effects since it was expected that combining them would further enhance NO production in endothelial cells. Using a human umbilical vein endothelial cell (HUVEC), the NO amount secreted in the culture supernatant was analyzed. Sesamin metabolite (SC1) was used in the experiments because it is a major metabolite in human blood after sesamin absorption. When cells were treated with DHA or EPA alone, they increased NO production in a concentration-dependent manner, whereas no change in NO production was observed for SC1. NO production increased when DHA and EPA were treated in combination with SC1, although the low DHA and EPA concentrations showed no difference in NO production. In the concentrations in which the combined effect was observed, SC1 activated eNOS via calcium signaling, whereas DHA and EPA activated eNOS via alterations in the membrane lipid environment. The combined effect of the two pathways was considered to have enhanced the eNOS activity. These results suggested that combining DHA, EPA, and sesamin might improve vascular endothelial function.

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.

Potential Mechanisms by Which Hydroxyeicosapentaenoic Acids Regulate Glucose Homeostasis in Obesity

Dysregulation of glucose metabolism in response to diet-induced obesity contributes toward numerous complications, such as insulin resistance and hepatic steatosis. Therefore, there is a need to develop effective strategies to improve glucose homeostasis. In this review, we first discuss emerging evidence from epidemiological studies and rodent experiments that increased consumption of EPA (either as oily fish, or dietary/pharmacological supplements) may have a role in preventing impairments in insulin and glucose homeostasis. We then review the current evidence on how EPA-derived metabolites known as hydroxyeicosapentaenoic acids (HEPEs) may be a major mode of action by which EPA exerts its beneficial effects on glucose and lipid metabolism. Notably, cell culture and rodent studies show that HEPEs prevent fat accumulation in metabolic tissues through peroxisome proliferator activated receptor (PPAR)-mediated mechanisms. In addition, activation of the resolvin E1 pathway, either by administration of EPA in the diet or via intraperitoneal administration of resolvin E1, improves hyperglycemia, hyperinsulinemia, and liver steatosis through multiple mechanisms. These mechanisms include shifting immune cell phenotypes toward resolution of inflammation and preventing dysbiosis of the gut microbiome. Finally, we present the next steps for this line of research that will drive future precision randomized clinical trials with EPA and its downstream metabolites. These include dissecting the variables that drive heterogeneity in the response to EPA, such as the baseline microbiome profile and fatty acid status, circadian rhythm, genetic variation, sex, and age. In addition, there is a critical need to further investigate mechanisms of action for HEPEs and to establish the concentration of HEPEs in differing tissues, particularly in response to consumption of oily fish and EPA-enriched supplements.

Short-Term Omega-3 Supplementation Modulates Novel Neurovascular and Fatty Acid Metabolic Proteome Changes in the Retina and Ophthalmic Artery of Mice with Targeted Cyp2c44 Gene Deletion

Cytochrome P450 (CYP) gene mutations are a common predisposition associated with glaucoma. Although the molecular mechanisms are largely unknown, omega-3 polyunsaturated fatty acids (ω-3 PUFA) and their CYP-derived bioactive mediators play crucial roles in the ocular system. Here, we elucidated the proteome and cell-signalling alterations attributed to the main human CYP2C gene deficiency using a homologous murine model (Cyp2c44^−/−), and unravelled the effects of acute ω-3 PUFA supplementation in two ocular vascular beds comprising the retrobulbar ophthalmic artery (OA) and retina (R). Male Cyp2c44^−/− mice (KO) and their floxed littermates (WT) were gavaged daily for 7 days with 0.01 mL/g of ω-3 PUFA composed of menhaden fish oil. Another group in respective strains served as vehicle-treated controls. OA and R were isolated at day 8 post-treatment (n = 9/group) and subjected to mass spectrometry (MS)-based proteomics and in silico bioinformatics analyses. Cyp2c44^−/− resulted in significant detrimental proteome changes associated with compromised vascular integrity and degeneration in the OA and R, respectively. However, notable changes in the OA after ω-3 PUFA intake were associated with the maintenance of intercellular junctional and endothelial cell functions, as well as activation of the fatty acid metabolic pathway in the KO mice. Conversely, ω-3 PUFA supplementation profoundly influenced the regulation of a large majority of retinal proteins involved in the preservation of neuronal and phototransduction activities in WT mice, namely synaptophysin, phosducin and guanylate cyclase-1, while significantly abrogating degenerative processes in the KO mice via the regulation of, namely, synaptotagmin-1 and beta-crystallin B2. In gist, this study demonstrated that dietary supplementation with ω-3 PUFA for a short period of seven days regulated specific neuro-vasculoprotective mechanisms to preserve the functionality of the OA and R in the absence of Cyp2c44. The potential adjunct use of ω-3 PUFA for glaucoma therapy needs further investigation.

Clinical significance of polyunsaturated fatty acids in the prevention of cardiovascular diseases

Cardiovascular diseases are one of the most important problems of modern medicine. They are associated with a large number of health care visits, hospitalizations and mortality. Prevention of atherosclerosis is one of the most effective strategies and should start as early as possible. Correction of lipid metabolism disorders is associated with definite clinical successes, both in primary prevention and in the prevention of complications of many cardiovascular diseases. A growing body of evidence suggests a multifaceted role for polyunsaturated fatty acids. They demonstrate a variety of functions in inflammation, both participating directly in a number of cellular processes and acting as a precursor for subsequent biosynthesis of lipid mediators. Extensive clinical data also support the importance of polyunsaturated fatty acids, but all questions have not been answered to date, indicating the need for further research.

Immune Function of Endothelial Cells: Evolutionary Aspects, Molecular Biology and Role in Atherogenesis

Atherosclerosis is one of the key problems of modern medicine, which is due to the high prevalence of atherosclerotic cardiovascular diseases and their significant share in the structure of morbidity and mortality in many countries. Atherogenesis is a complex chain of events that proceeds over many years in the vascular wall with the participation of various cells. Endothelial cells are key participants in vascular function. They demonstrate involvement in the regulation of vascular hemodynamics, metabolism, and innate immunity, which act as leading links in the pathogenesis of atherosclerosis. These endothelial functions have close connections and deep evolutionary roots, a better understanding of which will improve the prospects of early diagnosis and effective treatment.

Vegan nutrition: a preliminary guide for health professionals

Since the beginning of the 21st century, interest in vegan diets has been rapidly increasing in most countries. Misconceptions about vegan diets are widespread among the general population and health professionals. Vegan diets can be health-promoting and may offer certain important advantages compared to typical Western (and other mainstream) eating patterns. However, adequate dietary sources/supplements of nutrients of focus specific to vegan diets should be identified and communicated. Without supplements/fortified foods, severe vitamin B12 deficiency may occur. Other potential nutrients of focus are calcium, vitamin D, iodine, omega-3 fatty acids, iron, zinc, selenium, vitamin A, and protein. Ensuring adequate nutrient status is particularly important during pregnancy, lactation, infancy, and childhood. Health professionals are often expected to be able to provide advice on the topic of vegan nutrition, but a precise and practical vegan nutrition guide for health professionals is lacking. Consequently, it is important and urgent to provide such a set of dietary recommendations. It is the aim of this article to provide vegan nutrition guidelines, based on current evidence, which can easily be communicated to vegan patients/clients, with the goal of ensuring adequate nutrient status in vegans.

Potential effects of icosapent ethyl on cardiovascular outcomes in cigarette smokers: REDUCE-IT smoking

AIMS

Cigarette smoking is among the most well-established risk factors for adverse cardiovascular outcomes. We sought to determine whether icosapent ethyl (IPE), a highly purified form of eicosapentaenoic acid with antiatherothrombotic properties, may reduce the excessive risk of cardiovascular disease (CVD) attributable to smoking.

METHODS AND RESULTS

Reduction of Cardiovascular Events with Icosapent Ethyl Trial (REDUCE-IT) was a multinational, double-blind trial that randomized 8179 statin-treated patients with elevated triglycerides and CV risk to IPE or placebo, with a median follow-up period of 4.9 years. Icosapent ethyl reduced the primary composite endpoint [CV death, non-fatal myocardial infarction (MI), non-fatal stroke, coronary revascularization, or hospitalization for unstable angina] by 25% (P < 0.0001). In the current analyses, the effect of IPE was evaluated in REDUCE-IT using post hoc analyses based on smoking history. Groups were classified as current smokers (n = 1241), former smokers (n = 3672), and never smokers (n = 3264). Compared with placebo, IPE use in combined current and former smokers (n = 4913) was associated with significant reductions in time to the primary composite endpoint {hazard ratio: 0.77 [95% confidence interval (CI): 0.68-0.87]; P < 0.0001} and in total events [rate ratio: 0.71 (95% CI: 0.61-0.82); P < 0.0001]. These benefits remained significant when subdivided into current and former smokers (P = 0.04, P = 0.005), with reductions in the key secondary composite endpoint (P < 0.0001) and in the individual components of CV death or non-fatal MI (P = 0.04, P = 0.01) and fatal or non-fatal MI (P = 0.009, P = 0.01), respectively. Benefits were consistent and significant in non-smokers as well. Overall, there were similar estimated rates of first occurrences of primary CVD endpoints in current smokers (23.8%) and former smokers (23.0%) assigned to IPE compared with never smokers on placebo (25.7%).

CONCLUSION

In REDUCE-IT, IPE treatment was associated with a reduced risk of CV events in current and former smokers to levels observed in never smokers. While smoking cessation should always be recommended, these data raise the possibility that IPE treatment may attenuate CV hazards attributable to smoking.

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.

Omega-3-fatty acids: Do they prevent cardiovascular disease?

Despite cardiovascular disease (CVD) reductions with high-intensity statins, there remains residual risk among patients with metabolic disorders. Alongside low-density lipoproteins (LDL-C), elevated triglycerides (TG) are associated with incident CVD events. Omega-3 fatty acids (n3-FAs), specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), lower TG levels, but their ability to reduce CV risk has been highly inconsistent. Trials using icosapent ethyl (IPE), a purified EPA ethyl ester, produced reductions in CVD events and atherosclerotic plaque regression compared with mixed EPA/DHA formulations despite similar TG-reductions. The separate effects of EPA and DHA on tissue distribution, oxidative stress, inflammation, membrane structure and endothelial function may contribute to these discordant outcomes. Additional mechanistic trials will provide further insights into the role of n3-FAs in reducing CVD risk beyond TG lowering.

Prevention of Cardiovascular Events and Mortality With Icosapent Ethyl in Patients With Prior Myocardial Infarction

BACKGROUND

REDUCE-IT was a double-blind trial that randomized 8,179 statin-treated patients with controlled low-density lipoprotein cholesterol and moderately elevated triglycerides to icosapent ethyl (IPE) or placebo. There was a significant reduction in the primary endpoint, including death from cardiovascular (CV) causes. The specific impact of IPE among patients with prior myocardial infarction (MI) was unknown.

OBJECTIVES

Our goal was to examine the benefit of IPE on ischemic events among patients with prior MI in REDUCE-IT.

METHODS

We performed post hoc analyses of patients with prior MI. The primary endpoint was CV death, MI, stroke, coronary revascularization, or hospitalization for unstable angina. The key secondary endpoint was CV death, MI, or stroke.

RESULTS

A total of 3,693 patients had a history of prior MI. The primary endpoint was reduced from 26.1% to 20.2% with IPE vs placebo; HR: 0.74 (95% CI: 0.65-0.85; P = 0.00001). The key secondary endpoint was reduced from 18.0% to 13.3%; HR: 0.71 (95% CI: 0.61-0.84; P = 0.00006). There was also a significant 35% relative risk reduction in total ischemic events (P = 0.0000001), a 34% reduction in MI (P = 0.00009), a 30% reduction in CV death (P = 0.01), and a 20% lower rate of all-cause mortality (P = 0.054), although there was a slight increase in atrial fibrillation. Sudden cardiac death and cardiac arrest were also significantly reduced by 40% and 56%, respectively.

CONCLUSIONS

Patients with a history of prior MI in REDUCE-IT treated with IPE demonstrated large and significant relative and absolute risk reductions in ischemic events, including CV death. (A Study of AMR101 to Evaluate Its Ability to Reduce Cardiovascular Events in High Risk Patients With Hypertriglyceridemia and on Statin. The Primary Objective is to Evaluate the Effect of 4 g/Day AMR101 for Preventing the Occurrence of a First Major Cardiovascular Event. [REDUCE-IT]; NCT01492361).

Differentiating EPA from EPA/DHA in cardiovascular risk reduction

None of the clinical trials of omega-3 fatty acids using combinations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were able to show any effect on cardiovascular outcomes, despite reductions in triglyceride levels. In contrast, the Reduction of Cardiovascular Events With Icosapent Ethyl-Intervention Trial (REDUCE-IT), which employed high-dose (4 g) purified EPA, demonstrated a 25% reduction in atherosclerotic cardiovascular disease-related events compared with placebo (hazard ratio 0.75; 95% confidence interval 0.68-0.83; P < 0.001). Moreover, REDUCE-IT is the first clinical trial using a lipid-lowering agent as adjuvant therapy to a statin to show a significant reduction in cardiovascular mortality. Significant reductions in stroke, need for revascularization, and myocardial infarction were also observed. The pharmacology of EPA is distinct from that of DHA, with a differential effect on membrane structure, lipoprotein oxidation, and the production of downstream metabolites that promote the resolution of inflammation. Attained plasma levels of EPA may be an important determinant of efficacy, with a substudy of REDUCE-IT suggesting that the threshold for clinical benefit of EPA is approximately 100 μg/mL, a level achieved in only a minority of patients in other studies. No similar clinical trials of DHA monotherapy have been conducted, so no such threshold has been established. The results of the REDUCE-IT and the Japan EPA Lipid Intervention Study (JELIS) together affirm the efficacy of EPA therapy for cardiovascular disease risk reduction in certain patient populations.

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.

Treatment With Icosapent Ethyl to Reduce Ischemic Events in Patients With Prior Percutaneous Coronary Intervention: Insights From REDUCE-IT PCI

Background

Patients who undergo percutaneous coronary intervention (PCI) are at increased risk for recurrent cardiovascular events despite aggressive medical therapy.

Methods and Results

This post hoc analysis focused on the subset of patients with prior PCI enrolled in REDUCE‐IT (Reduction of Cardiovascular Events With Icosapent Ethyl–Intervention Trial), a multicenter, randomized, double‐blind, placebo‐controlled trial of icosapent ethyl versus placebo. Icosapent ethyl was added to statins in patients with low‐density lipoprotein cholesterol <100 mg/dL and fasting triglycerides 135–499 mg/dL. The primary end point was a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, coronary revascularization, or unstable angina requiring hospitalization. There were 8179 patients randomized in REDUCE‐IT followed for a median of 4.9 years, and 3408 (41.7%) of them had a prior PCI with a median follow‐up of 4.8 years. These patients were randomized a median of 2.9 years (11 days to 30.7 years) after PCI. Among patients treated with icosapent ethyl versus placebo, there was a 34% reduction in the primary composite end point (hazard ratio [HR], 0.66; 95% CI, 0.58–0.76; P<0.001; number needed to treat^{4.8 years}=12) and a 34% reduction in the key secondary composite end point of cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke (HR, 0.66; 95% CI, 0.56–0.79; P<0.001; NNT^{4.8 years}=19) versus placebo. Similarly, large reductions occurred in total coronary revascularizations and revascularization subtypes. There was also a 39% reduction in total events (rate ratio, 0.61; 95% CI, 0.52–0.72; P<0.001).

Conclusions

Among patients treated with statins with elevated triglycerides and a history of prior PCI, icosapent ethyl substantially reduced the risk of recurrent events during an average of ~5 years of follow‐up with a number needed to treat of only 12.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01492361.

Involvement of Fatty Acids and Their Metabolites in the Development of Inflammation in Atherosclerosis

Despite all the advances of modern medicine, atherosclerosis continues to be one of the most important medical and social problems. Atherosclerosis is the cause of several cardiovascular diseases, which are associated with high rates of disability and mortality. The development of atherosclerosis is associated with the accumulation of lipids in the arterial intima and the disruption of mechanisms that maintain the balance between the development and resolution of inflammation. Fatty acids are involved in many mechanisms of inflammation development and maintenance. Endothelial cells demonstrate multiple cross-linkages between lipid metabolism and innate immunity. In addition, these processes are linked to hemodynamics and the function of other cells in the vascular wall, highlighting the central role of the endothelium in vascular biology.