18-HEPE, an n-3 fatty acid metabolite released by macrophages, prevents pressure overload-induced maladaptive cardiac remodeling

One-Year Effects of High-Intensity Statin on Bioactive Lipids: Findings From the JUPITER Trial

BACKGROUND

Statin effects extend beyond low-density lipoprotein cholesterol reduction, potentially modulating the metabolism of bioactive lipids (BALs), crucial for biological signaling and inflammation. These bioactive metabolites may serve as metabolic footprints, helping uncover underlying processes linked to pleiotropic effects of statins and yielding a better understanding of their cardioprotective properties. This study aimed to investigate the impact of high-intensity statin therapy versus placebo on plasma BALs in the JUPITER trial (Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin; NCT00239681), a randomized primary prevention trial involving individuals with low-density lipoprotein cholesterol <130 mg/dL and high-sensitivity C-reactive protein ≥2 mg/L.

METHODS

Using a nontargeted mass spectrometry approach, over 11 000 lipid features were assayed from baseline and 1-year plasma samples from cardiovascular disease noncases from 2 nonoverlapping nested substudies: JUPITERdiscovery (n=589) and JUPITERvalidation (n=409). The effect of randomized allocation of rosuvastatin 20 mg versus placebo on BALs was examined by fitting a linear regression with delta values (∆=year 1-baseline) adjusted for age and baseline levels of each feature. Significant associations in discovery were analyzed in the validation cohort. Multiple comparisons were adjusted using 2-stage overall false discovery rate.

RESULTS

We identified 610 lipid features associated with statin randomization with significant replication (overall false discovery rate, <0.05), including 26 with annotations. Statin therapy significantly increased levels of 276 features, including BALs with anti-inflammatory activity and arterial vasodilation properties. Concurrently, 334 features were significantly lowered by statin therapy, including arachidonic acid and proinflammatory and proplatelet aggregation BALs. By contrast, statin therapy reduced an eicosapentaenoic acid-derived hydroxyeicosapentaenoic acid metabolite, which may be related to impaired glucose metabolism. Additionally, we observed sex-related differences in 6 lipid metabolites and 6 unknown features.

CONCLUSIONS

Statin allocation was significantly associated with upregulation of BALs with anti-inflammatory, antiplatelet aggregation and antioxidant properties and downregulation of BALs with proinflammatory and proplatelet aggregation activity, supporting the pleiotropic effects of statins beyond low-density lipoprotein cholesterol reduction.

Is Lipid Metabolism of Value in Cancer Research and Treatment? Part II: Role of Specialized Pro-Resolving Mediators in Inflammation, Infections, and Cancer

Acute inflammation is the body's first defense in response to pathogens or injury that is partially governed by a novel genus of endogenous lipid mediators that orchestrate the resolution of inflammation, coined specialized pro-resolving mediators (SPMs). SPMs, derived from omega-3-polyunstaturated fatty acids (PUFAs), include the eicosapentaenoic acid-derived and docosahexaenoic acid-derived Resolvins, Protectins, and Maresins. Herein, we review their biosynthesis, structural characteristics, and therapeutic effectiveness in various diseases such as ischemia, viral infections, periodontitis, neuroinflammatory diseases, cystic fibrosis, lung inflammation, herpes virus, and cancer, especially focusing on therapeutic effectiveness in respiratory inflammation and ischemia-related injuries. Resolvins are sub-nanomolar potent agonists that accelerate the resolution of inflammation by reducing excessive neutrophil infiltration, stimulating macrophage functions including phagocytosis, efferocytosis, and tissue repair. In addition to regulating neutrophils and macrophages, Resolvins control dendritic cell migration and T cell responses, and they also reduce the pro-inflammatory cytokines, proliferation, and metastasis of cancer cells. Importantly, several lines of evidence have demonstrated that Resolvins reduce tumor progression in melanoma, oral squamous cell carcinoma, lung cancer, and liver cancer. In addition, Resolvins enhance tumor cell debris clearance by macrophages in the tumor's microenvironment. Resolvins, with their unique stereochemical structure, receptors, and biosynthetic pathways, provide a novel therapeutical approach to activating resolution mechanisms during cancer progression.

Myricanol improves metabolic profiles in dexamethasone induced lipid and protein metabolism disorders in mice

Myricanol (MY) is one of the main active components from bark of Myrica Rubra. It is demonstrated that MY rescues dexamethasone (DEX)-induced muscle dysfunction via activating silent information regulator 1 (SIRT1) and increasing adenosine 5'-monophosphate-activated protein kinase (AMPK) phosphorylation. Since SIRT1 and AMPK are widely involved in the metabolism of nutrients, we speculated that MY may exert beneficial effects on DEX-induced metabolic disorders. This study for the first time applied widely targeted metabolomics to investigate the beneficial effects of MY on glucose, lipids, and protein metabolism in DEX-induced metabolic abnormality in mice. The results showed that MY significantly reversed DEX-induced soleus and gastrocnemius muscle weight loss, muscle fiber damage, and muscle strength loss. MY alleviated DEX-induced metabolic disorders by increasing SIRT1 and glucose transporter type 4 (GLUT4) expressions. Additionally, myricanol prevented muscle cell apoptosis and atrophy by inhibiting caspase 3 cleavages and muscle ring-finger protein-1 (MuRF1) expression. Metabolomics showed that MY treatment reversed the serum content of carnitine ph-C1, palmitoleic acid, PS (16:0_17:0), PC (14:0_20:5), PE (P-18:1_16:1), Cer (t18:2/38:1(2OH)), four amino acids and their metabolites, and 16 glycerolipids in DEX mice. Kyoto encyclopedia of genes and genomes (KEGG) and metabolic set enrichment analysis (MSEA) analysis revealed that MY mainly affected metabolic pathways, glycerolipid metabolism, lipolysis, fat digestion and absorption, lipid and atherosclerosis, and cholesterol metabolism pathways through regulation of metabolites involved in glutathione, butanoate, vitamin B6, glycine, serine and threonine, arachidonic acid, and riboflavin metabolism. Collectively, MY can be used as an attractive therapeutic agent for DEX-induced metabolic abnormalities.

Synbiotic Bacillus megaterium DSM 32963 and n-3 PUFA Salt Composition Elevates Pro-Resolving Lipid Mediator Levels in Healthy Subjects: A Randomized Controlled Study

Beneficial health effects of omega-3 polyunsaturated fatty acids (n-3 PUFA) are partly attributed to specialized pro-resolving mediators (SPMs), which promote inflammation resolution. Strategies to improve n-3 PUFA conversion to SPMs may, therefore, be useful to treat or prevent chronic inflammatory disorders. Here, we explored a synbiotic strategy to increase circulating SPM precursor levels. Healthy participants (n = 72) received either SynΩ3 (250 mg eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) lysine salts; two billion CFU Bacillus megaterium; n = 23), placebo (n = 24), or fish oil (300 mg EPA plus DHA; N = 25) capsules daily for 28 days in a randomized, double-blind placebo-controlled parallel 3-group design. Biomarkers were assessed at baseline and after 2 and 28 days of intervention. The primary analysis involved the comparison between SynΩ3 and placebo. In addition, SynΩ3 was compared to fish oil. The synbiotic SynΩ3 comprising Bacillus megaterium DSM 32963 and n-3 PUFA salts significantly increased circulating SPM precursor levels, including 18-hydroxy-eicosapentaenoic acid (18-HEPE) plus 5-HEPE, which was not achieved to this extent by fish oil with a similar n-3 PUFA content. Omega-3 indices were increased slightly by both SynΩ3 and fish oil. These findings suggest reconsidering conventional n-3 PUFA supplementation and testing the effectiveness of SynΩ3 particularly in conditions related to inflammation.

Serum albumin levels and risk of atrial fibrillation: a Mendelian randomization study

Objective

Although several observational studies have linked serum albumin to cardiovascular disease and considered it as an important biomarker, little is known about whether increasing or maintaining serum albumin levels can effectively improve the prognosis of patients with atrial fibrillation. Therefore, this study aims to further explore the causal relationship between serum albumin and atrial fibrillation and its potential mechanism.

Method

Using data from large-scale genome-wide association studies, we conducted a two-sample Mendelian randomization (MR) analysis and a mediation MR analysis, using serum albumin as the exposure variable and atrial fibrillation as the outcome variable. We included 486 serum metabolites as potential mediating factors. To increase the robustness of the analysis, we applied five statistical methods, including inverse variance weighted, weighted median, MR-Egger, simple mode, and weighted mode. Validate the MR results using Bayesian weighted Mendelian randomization method.

Result

The results of the MR analysis indicate a significant inverse association between genetically predicted serum albumin concentration (g/L) and the risk of atrial fibrillation (Beta = -0.172, OR = 0.842, 95% CI: 0.753-0.941, p = 0.002). Further mediation MR analysis revealed that serum albumin may mediate the causal relationship with atrial fibrillation by affecting two serum metabolites, docosatrienoate and oleate/vaccenate, and the mediating effect was significant. In addition, all our instrumental variables showed no heterogeneity and level-multiplicity in the MR analysis. To verify the stability of the results, we also conducted a sensitivity analysis using the leave-one-out method, and the results further confirmed that our findings were robust and reliable. Finally, we conducted a validation using the Bayesian weighted Mendelian randomization method, which demonstrated the reliability of our causal inference results.

Conclusion

This study strongly demonstrates the causal relationship between serum albumin and reduced risk of atrial fibrillation through genetic methods, and reveals the key mediating role of two serum metabolites in this relationship. These findings not only provide a new perspective for our understanding of the role of serum albumin in atrial fibrillation, but also provide new ideas for the prevention and treatment strategies of atrial fibrillation.

Emerging mechanisms of obesity-associated immune dysfunction

Obesity is associated with a wide range of complications, including type 2 diabetes mellitus, cardiovascular disease, hypertension and nonalcoholic fatty liver disease. Obesity also increases the incidence and progression of cancers, autoimmunity and infections, as well as lowering vaccine responsiveness. A unifying concept across these differing diseases is dysregulated immunity, particularly inflammation, in response to metabolic overload. Herein, we review emerging mechanisms by which obesity drives inflammation and autoimmunity, as well as impairing tumour immunosurveillance and the response to infections. Among these mechanisms are obesity-associated changes in the hormones that regulate immune cell metabolism and function and drive inflammation. The cargo of extracellular vesicles derived from adipose tissue, which controls cytokine secretion from immune cells, is also dysregulated in obesity, in addition to impairments in fatty acid metabolism related to inflammation. Furthermore, an imbalance exists in obesity in the biosynthesis and levels of polyunsaturated fatty acid-derived oxylipins, which control a range of outcomes related to inflammation, such as immune cell chemotaxis and cytokine production. Finally, there is a need to investigate how obesity influences immunity using innovative model systems that account for the heterogeneous nature of obesity in the human population.

Lipid metabolism reprogramming in cardiac fibrosis

Cardiac fibrosis is a critical pathophysiological process that occurs with diverse types of cardiac injury. Lipids are the most important bioenergy substrates for maintaining optimal heart performance and act as second messengers to transduce signals within cardiac cells. However, lipid metabolism reprogramming is a double-edged sword in the regulation of cardiomyocyte homeostasis and heart function. Moreover, lipids can exert diverse effects on cardiac fibrosis through different signaling pathways. In this review, we provide a brief overview of aberrant cardiac lipid metabolism and recent progress in pharmacological research targeting lipid metabolism alterations in cardiac fibrosis.

Specialized pro-resolving mediators in vascular inflammation and atherosclerotic cardiovascular disease

Timely resolution of the acute inflammatory response (or inflammation resolution) is an active, highly coordinated process that is essential to optimal health. Inflammation resolution is regulated by specific endogenous signalling molecules that function as 'stop signals' to terminate the inflammatory response when it is no longer needed; to actively promote healing, regeneration and tissue repair; and to limit pain. Specialized pro-resolving mediators are a superfamily of signalling molecules that initiate anti-inflammatory and pro-resolving actions. Without an effective and timely resolution response, inflammation can become chronic, a pathological state that is associated with many widely occurring human diseases, including atherosclerotic cardiovascular disease. Uncovering the mechanisms of inflammation resolution failure in cardiovascular diseases and identifying useful biomarkers for non-resolving inflammation are unmet needs. In this Review, we discuss the accumulating evidence that supports the role of non-resolving inflammation in atherosclerosis and the use of specialized pro-resolving mediators as therapeutic tools for the treatment of atherosclerotic cardiovascular disease. We highlight open questions about therapeutic strategies and mechanisms of disease to provide a framework for future studies on the prevention and treatment of atherosclerosis.

Enhanced Production of EPA-Derived Anti-Inflammatory Metabolites after Oral Administration of a Novel Self-Emulsifying Highly Purified EPA Ethyl Ester Formulation (MND-2119)

AIMS

MND-2119 is a novel once-daily dose self-emulsifying formulation of highly purified eicosapentaenoic acid ethyl ester (EPA-E) and is approved as an antihyperlipidemia agent in Japan. It has improved absorption and achieves higher plasma EPA concentrations at Cmax than conventional EPA-E. In the JELIS trial, concomitant use of EPA-E with statin therapy significantly reduced atherosclerotic cardiovascular disease (ASCVD) risks. As a potential mechanism of action of EPA, endogenous formation of EPA-derived anti-inflammatory metabolites is receiving greater attention. This study aims to investigate the endogenous formation of EPA-derived anti-inflammatory metabolites following single and multiple administrations of MND-2119.

METHODS

Healthy adult male subjects were randomly assigned to a nonintervention (control) group, MND-2119 2-g/day group, MND-2119 4-g/day group, or EPA-E 1.8-g/day group for 7 days (N=8 per group). Plasma fatty acids and EPA-derived metabolites were evaluated. Peripheral blood neutrophils were isolated, and the production of EPA-derived metabolites from in vitro stimulated neutrophils was evaluated.

RESULTS

After single and multiple administrations of MND-2119 2 g/day, there were significant increases in plasma EPA concentration, 18-hydroxyeicosapentaenoic acid (18-HEPE), and 17,18-epoxyeicosatetraenoic acid compared with those of EPA-E 1.8 g/day. They were further increased with MND-2119 4 g/day administration. In neutrophils, the EPA concentration in the MND-2119 2-g/day group was significantly higher compared with that in the EPA-E 1.8-g/day group after multiple administration, and 18-HEPE production was positively correlated with EPA concentration. No safety issues were noted.

CONCLUSIONS

These results demonstrate that MND-2119 increases the plasma and cellular concentrations of EPA and EPA-derived metabolites to a greater extent than conventional EPA-E formulations.

Infectious neutrophil deployment is regulated by resolvin D4

Neutrophils reside in the bone marrow (BM), ready for deployment to sites of injury/infection, initiating inflammation and its resolution. Here, we report that distal infections signal to the BM via resolvins to regulate granulopoiesis and BM neutrophil deployment. Emergency granulopoiesis during peritonitis evoked changes in BM resolvin D1 (RvD1) and BM RvD4. We found that leukotriene B4 stimulates neutrophil deployment. RvD1 and RvD4 each limited neutrophilic infiltration to infections, and differently regulated BM myeloid populations: RvD1 increased reparative monocytes, and RvD4 regulated granulocytes. RvD4 disengaged emergency granulopoiesis, prevented excess BM neutrophil deployment, and acted on granulocyte progenitors. RvD4 also stimulated exudate neutrophil, monocyte, and macrophage phagocytosis, and enhanced bacterial clearance. This mediator accelerated both neutrophil apoptosis and clearance by macrophages, thus expediting the resolution phase of inflammation. RvD4 stimulated phosphorylation of ERK1/2 and STAT3 in human BM-aspirate-derived granulocytes. RvD4 in the 1 to 100 nM range stimulated whole-blood neutrophil phagocytosis of Escherichia coli. RvD4 increased BM macrophage efferocytosis of neutrophils. Together, these results demonstrate the novel functions of resolvins in granulopoiesis and neutrophil deployment, contributing to the resolution of infectious inflammation.

Humanization of the Reaction Specificity of Mouse Alox15b Inversely Modified the Susceptibility of Corresponding Knock-In Mice in Two Different Animal Inflammation Models

Mammalian arachidonic acid lipoxygenases (ALOXs) have been implicated in the pathogenesis of inflammatory diseases, and its pro- and anti-inflammatory effects have been reported for different ALOX-isoforms. Human ALOX15B oxygenates arachidonic acid to its 15-hydroperoxy derivative, whereas the corresponding 8-hydroperoxide is formed by mouse Alox15b (Alox8). This functional difference impacts the biosynthetic capacity of the two enzymes for creating pro- and anti-inflammatory eicosanoids. To explore the functional consequences of the humanization of the reaction specificity of mouse Alox15b in vivo, we tested Alox15b knock-in mice that express the arachidonic acid 15-lipoxygenating Tyr603Asp and His604Val double mutant of Alox15b, instead of the arachidonic acid 8-lipoxygenating wildtype enzyme, in two different animal inflammation models. In the dextran sodium sulfate-induced colitis model, female Alox15b-KI mice lost significantly more bodyweight during the acute phase of inflammation and recovered less rapidly during the resolution phase. Although we observed significant differences in the colonic levels of selected pro- and anti-inflammatory eicosanoids during the time-course of inflammation, there were no differences between the two genotypes at any time-point of the disease. In Freund's complete adjuvant-induced paw edema model, Alox15b-KI mice were less susceptible than outbred wildtype controls, though we did not observe significant differences in pain perception (Hargreaves-test, von Frey-test) when the two genotypes were compared. our data indicate that humanization of the reaction specificity of mouse Alox15b (Alox8) sensitizes mice for dextran sodium sulfate-induced experimental colitis, but partly protects the animals in the complete Freund's adjuvant-induced paw edema model.

FFAR4 regulates cardiac oxylipin balance to promote inflammation resolution in HFpEF secondary to metabolic syndrome

Heart failure with preserved ejection fraction (HFpEF) is a complex clinical syndrome, but a predominant subset of HFpEF patients has metabolic syndrome (MetS). Mechanistically, systemic, nonresolving inflammation associated with MetS might drive HFpEF remodeling. Free fatty acid receptor 4 (Ffar4) is a GPCR for long-chain fatty acids that attenuates metabolic dysfunction and resolves inflammation. Therefore, we hypothesized that Ffar4 would attenuate remodeling in HFpEF secondary to MetS (HFpEF-MetS). To test this hypothesis, mice with systemic deletion of Ffar4 (Ffar4KO) were fed a high-fat/high-sucrose diet with L-NAME in their water to induce HFpEF-MetS. In male Ffar4KO mice, this HFpEF-MetS diet induced similar metabolic deficits but worsened diastolic function and microvascular rarefaction relative to WT mice. Conversely, in female Ffar4KO mice, the diet produced greater obesity but no worsened ventricular remodeling relative to WT mice. In Ffar4KO males, MetS altered the balance of inflammatory oxylipins systemically in HDL and in the heart, decreasing the eicosapentaenoic acid-derived, proresolving oxylipin 18-hydroxyeicosapentaenoic acid (18-HEPE), while increasing the arachidonic acid-derived, proinflammatory oxylipin 12-hydroxyeicosatetraenoic acid (12-HETE). This increased 12-HETE/18-HEPE ratio reflected a more proinflammatory state both systemically and in the heart in male Ffar4KO mice and was associated with increased macrophage numbers in the heart, which in turn correlated with worsened ventricular remodeling. In summary, our data suggest that Ffar4 controls the proinflammatory/proresolving oxylipin balance systemically and in the heart to resolve inflammation and attenuate HFpEF remodeling.

Pathophysiological Involvement of Mast Cells and the Lipid Mediators in Pulmonary Vascular Remodeling

Mast cells are responsible for IgE-dependent allergic responses, but they also produce various bioactive mediators and contribute to the pathogenesis of various cardiovascular diseases, including pulmonary hypertension (PH). The importance of lipid mediators in the pathogenesis of PH has become evident in recent years, as exemplified by prostaglandin I2, the most central therapeutic target in pulmonary arterial hypertension. New bioactive lipids other than eicosanoids have also been identified that are associated with the pathogenesis of PH. However, it remains largely unknown how mast cell-derived lipid mediators are involved in pulmonary vascular remodeling. Recently, it has been demonstrated that mast cells produce epoxidized n-3 fatty acid (n-3 epoxides) in a degranulation-independent manner, and that n-3 epoxides produced by mast cells regulate the abnormal activation of pulmonary fibroblasts and suppress the progression of pulmonary vascular remodeling. This review summarizes the role of mast cells and bioactive lipids in the pathogenesis of PH. In addition, we introduce the pathophysiological role and therapeutic potential of n-3 epoxides, a mast cell-derived novel lipid mediator, in the pulmonary vascular remodeling in PH. Further knowledge of mast cells and lipid mediators is expected to lead to the development of innovative therapies targeting pulmonary vascular remodeling.

Over-the-counter fish oil supplementation and pro-resolving and pro-inflammatory lipid mediators in rheumatoid arthritis

OBJECTIVE

Little is known about the effects of over-the-counter fish oil (FO) supplements on circulating omega-3 polyunsaturated fatty acid (n-3 PUFA)-derived specialized pro-resolving mediators (SPMs), nor about whether having a chronic inflammatory disease such as rheumatoid arthritis (RA) influences SPM levels. We investigated associations between over-the-counter n-3 PUFA FO supplementation and circulating SPMs among patients with vs. without RA.

METHODS

We studied 104 participants: 26 with RA taking FO matched by age and sex to 26 with RA not taking FO, 26 without RA taking FO, and 26 without RA not taking FO. Targeted-liquid chromatography-tandem mass spectroscopy was performed on patient plasma to identify and quantify 27 lipid mediators (including eicosanoids and SPMs). We performed t-tests and then multivariable linear regression analyses to assess whether having RA or taking FO supplements was associated with circulating lipid mediator concentrations, adjusting for age, race, sex, smoking, body mass index, and current medication use (statins, prednisone and immunomodulators among RA cases only). We tested for interactions between FO supplementation and RA status. We also conducted Spearman's correlations between EPA, DHA, and ARA and their downstream metabolites.

RESULTS

Among patients who were taking FO compared to those who were not, in multivariable- adjusted analyses, SPM substrates EPA and DHA were both elevated as were several of their pro-resolving bioactive products, including 15- and 18-HEPE from EPA, and 14- and 17-HDHA from DHA, which are substrates for specific SPMs. While E-series and D-series resolvins were present and identified, we did not find statistical elevations of other SPMs. Results were similar among patients with RA and patients without RA, taking vs. not taking FO supplementation (no formal statistical interaction observed). There was a strong positive correlation between EPA and DHA and their immediate downstream SPM precursors (18-HEPE and15-HEPE from EPA; 17-HDHA and 14-HDHA from DHA) among all patients.

CONCLUSION

Patients taking FO supplements, regardless of RA status, not only had higher blood levels of EPA and DHA, but also of their enzymatic products 18-HEPE (E-series resolvin precursors), 15-HEPE and 17-HDHA (D-series resolvin and protectin precursors). Patients with RA, an inflammatory autoimmune disease, may be able to augment some SPM precursor reserves, similarly to matched controls without RA, by taking oral FO supplements.

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.

Clostridium butyricum-induced ω-3 fatty acid 18-HEPE elicits anti-influenza virus pneumonia effects through interferon-λ upregulation

The precise mechanism by which butyrate-producing bacteria in the gut contribute to resistance to respiratory viral infections remains to be elucidated. Here, we describe a gut-lung axis mechanism and report that orally administered Clostridium butyricum (CB) enhances influenza virus infection resistance through upregulation of interferon (IFN)-λ in lung epithelial cells. Gut microbiome-induced ω-3 fatty acid 18-hydroxy eicosapentaenoic acid (18-HEPE) promotes IFN-λ production through the G protein-coupled receptor (GPR)120 and IFN regulatory factor (IRF)-1/-7 activations. CB promotes 18-HEPE production in the gut and enhances ω-3 fatty acid sensitivity in the lungs by promoting GPR120 expression. This study finds a gut-lung axis mechanism and provides insights into the treatments and prophylaxis for viral respiratory infections.

Lipolysis-derived linoleic acid drives beige fat progenitor cell proliferation

De novo beige adipocyte biogenesis involves the proliferation of progenitor cells in white adipose tissue (WAT); however, what regulates this process remains unclear. Here, we report that in mouse models but also in human tissues, WAT lipolysis-derived linoleic acid triggers beige progenitor cell proliferation following cold acclimation, β3-adrenoceptor activation, and burn injury. A subset of adipocyte progenitors, as marked by cell surface markers PDGFRα or Sca1 and CD81, harbored cristae-rich mitochondria and actively imported linoleic acid via a fatty acid transporter CD36. Linoleic acid not only was oxidized as fuel in the mitochondria but also was utilized for the synthesis of arachidonic acid-derived signaling entities such as prostaglandin D2. Oral supplementation of linoleic acid was sufficient to stimulate beige progenitor cell proliferation, even under thermoneutral conditions, in a CD36-dependent manner. Together, this study provides mechanistic insights into how diverse pathophysiological stimuli, such as cold and burn injury, promote de novo beige fat biogenesis.

Genetic deletion of Cyp4f18 disrupts the omega-3 epoxidation pathway and results in psoriasis-like dermatitis

Cyp4f18 catalyzes the conversion of n-3 polyunsaturated fatty acids (PUFAs) into omega-3 epoxides, such as 17,18-epoxyeicosatetraenoic acid (17,18-EpETE) and 19,20-epoxydocosapentaenoic acid (19,20-EpDPE) from eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), respectively. Cyp4f18-deficient mice spontaneously develop psoriasis-like dermatitis. A significant increase in the number of IL-17A-positive gamma delta (γδ) T cells in the skin and enlargement of draining lymph nodes was observed. These symptoms were drastically suppressed by antibiotic treatment. Cyp4f18 is highly expressed in dendritic cells (DCs), and Cyp4f18-deficient bone marrow-derived dendritic cells (BMDCs) show markedly increased expression levels of cytokines such as IL-23 and IL-1β in response to lipopolysaccharide (LPS) stimulation. Lipidomic analysis of lymph nodes and BMDCs revealed a significant decrease in a series of omega-3 epoxidized metabolites. Among them, 17,18-dihydroxyeicosatetraenoic acid (17,18-diHETE), a vicinal diol derived from EPA omega-3 epoxidation suppressed IL-23 production in LPS-stimulated BMDCs in Cyp4f18-deficient mice. These results demonstrate that Cyp4f18 endogenously produces omega-3-epoxidized metabolites in the draining lymph nodes, and these metabolites contribute to skin homeostasis by suppressing the excessive activation of the IL-23/IL-17 axis initiated by DCs.

Targeting NRF2-KEAP1 axis by Omega-3 fatty acids and their derivatives: Emerging opportunities against aging and diseases

The transcription factor NRF2 and its endogenous inhibitor KEAP1 play a crucial role in the maintenance of cellular redox homeostasis by regulating the gene expression of diverse networks of antioxidant, anti-inflammatory, and detoxification enzymes. Therefore, activation of NRF2 provides cytoprotection against numerous pathologies, including age-related diseases. An age-associated loss of NRF2 function may be a key driving force behind the aging phenotype. Recently, numerous NRF2 inducers have been identified and some of them are promising candidates to restore NRF2 transcriptional activity during aging. Emerging evidence indicates that omega-3 (n-3) polyunsaturated fatty acids (PUFAs) and their electrophilic derivatives may trigger a protective response via NRF2 activation, rescuing or maintaining cellular redox homeostasis. In this review, we provide an overview of the NRF2-KEAP1 system and its dysregulation in aging cells. We also summarize current studies on the modulatory role of n-3 PUFAs as potential agents to prevent multiple chronic diseases and restore the age-related impairment of NRF2 function.

Fish oil supplementation in patients with and without systemic lupus erythematosus: targeting pro-inflammatory and pro-resolving lipid mediators

Background:

Omega-3 fatty acid-derived “specialized pro-resolving mediators” are lipid mediators (LM) central to inflammation resolution. We investigated whether fish oil (FO) supplementation was associated with pro-inflammatory and pro-resolving LM levels in SLE patients compared to matched non-SLE controls.

Methods:

16 SLE patients taking FO were matched (age, sex, race) to 16 non-SLE controls taking FO. Another 16 SLE patients not taking FO were matched to 16 non-SLE patients not taking FO. Demographic/clinical data were obtained by medical record review. Targeted liquid chromatography-tandem spectrometry was performed with plasma to quantify 27 LM. Multivariable linear analyses examined how SLE, FO, and their interaction were associated with LM levels, adjusting for potential confounders including inflammatory markers and SLE disease activity for SLE cases only.

Results:

Higher levels of pro-inflammatory LMs were found in patients with SLE not on FO, compared to controls not on FO, particularly TXB₂ (p=0.03). Lower levels of many SPMs were observed among patients with SLE taking FO compared to controls taking FO, including LXB₄ (p<0.01) and 18-HEPE (p=0.04). In case-only analyses, taking FO was associated with higher 17-HDHA levels (p=0.05). There were no multiplicative interactions between FO effect and SLE status, and after adjustment for multiple comparisons, few of the associations persisted.

Conclusion:

In this cross-sectional exploratory study, higher levels of inflammatory LM and lower levels of SPMs were found in SLE patients than controls, among those taking and not taking FO. Further studies investigating the potentially beneficial biologic effects of FO preparations and doses in SLE are needed.

Trans-myocardial omega-3 fatty acid gradient in coronary microvascular dysfunction

Background

Cardiac remodeling is a process mediated, in part, by 18-hydroxyeicosapentaenoic acid (HEPE), a metabolite of the omega-3 polyunsaturated fatty acid, eicosapentaenoic acid (EPA). We hypothesized that trans-myocardial levels of 18-HEPE could inform the pathophysiologic processes involved in heart failure with preserved ejection fraction (HFpEF).

Methods

We measured the concentration of 18-HEPE and EPA in trans-myocardial plasma samples from 10 subjects enrolled in The Women's Ischemia Syndrome Evaluation [WISE] Mechanisms of Coronary Microvascular Dysfunction Leading to Pre-HFpEF project.

Results

Concentrations of 18-HEPE were significantly lower in coronary venous compared to the aortic plasma (270.5 pg/mL [212.8-480.8] vs. 430.5 pg/mL [299.5-655.8], p = 0.0039). There was a significant correlation between the concentrations of coronary venous EPA and aortic 18-HEPE (r = 0.94, p = 0.0002), and aortic EPA and aortic 18-HEPE (r = 0.82, p = 0.0058).

Conclusions

Results of this small pilot study support the suggestion that 18-HEPE is synthesized outside the heart and utilized within the myocardial bed.

Lipid profiling reveals the presence of unique lipid mediators in human milk from healthy and mastitic subjects

Milk lipids are an important energy source for infants, but the composition of milk lipids has not yet been clarified in detail. In this study, we analyzed free fatty acids and their metabolites in milk from humans and cows. In comparison to cow milk, human milk showed a higher content of free fatty acids including polyunsaturated fatty acids, especially ω-3 fatty acids and their metabolites. Polyunsaturated fatty acids were enriched at an early period of lactation, while saturated fatty acids did not change significantly over the period. Moreover, human milk contained high levels of ω-3 fatty acid metabolites, particularly 18-hydroxyeicosapentaenoic acid, an eicosapentaenoic acid-derived metabolite with anti-inflammatory activity. In comparison with human normal milk, thromboxane B₂ and protectin D1 levels were significantly elevated in milk from individuals with mastitis, suggesting that these lipid mediators could be potential biomarkers of obstructive mastitis. Overall, the unique lipid profile of human milk supports the efficacy of breast-feeding for supply of more nutritional and bioactive lipids in comparison to artificial or cow milk to infants, in whom digestive and absorptive functions are still immature.

A Review of Oxylipins in Alzheimer's Disease and Related Dementias (ADRD): Potential Therapeutic Targets for the Modulation of Vascular Tone and Inflammation

There is now a convincing body of evidence from observational studies that the majority of modifiable Alzheimer's disease and related dementia (ADRD) risk factors are vascular in nature. In addition, the co-existence of cerebrovascular disease with AD is more common than AD alone, and conditions resulting in brain ischemia likely promote detrimental effects of AD pathology. Oxylipins are a class of bioactive lipid mediators derived from the oxidation of long-chain polyunsaturated fatty acids (PUFAs) which act as modulators of both vascular tone and inflammation. In vascular cognitive impairment (VCI), there is emerging evidence that oxylipins may have both protective and detrimental effects on brain structure, cognitive performance, and disease progression. In this review, we focus on oxylipin relationships with vascular and inflammatory risk factors in human studies and animal models pertinent to ADRD. In addition, we discuss future research directions with the potential to impact the trajectory of ADRD risk and disease progression.

Dirty Jobs: Macrophages at the Heart of Cardiovascular Disease

Cardiovascular disease (CVD) is one of the greatest public health concerns and is the leading cause of morbidity and mortality in the United States and worldwide. CVD is a broad yet complex term referring to numerous heart and vascular conditions, all with varying pathologies. Macrophages are one of the key factors in the development of these conditions. Macrophages play diverse roles in the maintenance of cardiovascular homeostasis, and an imbalance of these mechanisms contributes to the development of CVD. In the current review, we provide an in-depth analysis of the diversity of macrophages, their roles in maintaining tissue homeostasis within the heart and vasculature, and the mechanisms through which imbalances in homeostasis may lead to CVD. Through this review, we aim to highlight the potential importance of macrophages in the identification of preventative, diagnostic, and therapeutic strategies for patients with CVD.

Hemodialysis and biotransformation of erythrocyte epoxy fatty acids in peripheral tissue

Cardiovascular disease is the leading cause of mortality in patients with renal failure. Red blood cells (RBCs) are potential reservoirs for epoxy fatty acids (oxylipins) that regulate cardiovascular function. Hemoglobin exhibits pseudo-lipoxygenase activity in vitro. We previously assessed the impact of single hemodialysis (HD) treatment on RBC epoxy fatty acids status in circulating arterial blood and found that eicosanoids in oxygenated RBCs could be particularly vulnerable in chronic kidney disease and hemodialysis. The purpose of the present study was to evaluate the differences of RBC epoxy fatty acids profiles in arterial and venous blood in vivo (AV differences) from patients treated by HD treatment. We collected arterial and venous blood samples in upper limbs from 12 end-stage renal disease (ESRD) patients (age 72±12 years) before and after HD treatment. We measured oxylipins derived from cytochrome P450 (CYP) monooxygenase and lipoxygenase (LOX)/CYP ω/(ω-1)-hydroxylase pathways in RBCs by LC-MS/MS tandem mass spectrometry. Our data demonstrate arteriovenous differences in LOX pathway metabolites in RBCs after dialysis, including numerous hydroxyeicosatetraenoic acids (HETEs), hydroxydocosahexaenoic acids (HDHAs) and hydroxyeicosapentaenoic acids (HEPEs). We detected more pronounced changes in free metabolites in RBCs after HD, as compared with the total RBC compartment. Hemodialysis treatment did not affect the majority of CYP and CYP ω/(ω-1)-hydroxylase products in RBCs. Our data indicate that erythro-metabolites of the LOX pathway are influenced by renal-replacement therapies, which could have deleterious effects in the circulation.

Omega-3 fatty acid epoxides produced by PAF-AH2 in mast cells regulate pulmonary vascular remodeling

Pulmonary hypertension is a fatal rare disease that causes right heart failure by elevated pulmonary arterial resistance. There is an unmet medical need for the development of therapeutics focusing on the pulmonary vascular remodeling. Bioactive lipids produced by perivascular inflammatory cells might modulate the vascular remodeling. Here, we show that ω-3 fatty acid-derived epoxides (ω-3 epoxides) released from mast cells by PAF-AH2, an oxidized phospholipid-selective phospholipase A2, negatively regulate pulmonary hypertension. Genetic deletion of Pafah2 in mice accelerate vascular remodeling, resulting in exacerbation of hypoxic pulmonary hypertension. Treatment with ω-3 epoxides suppresses the lung fibroblast activation by inhibiting TGF-β signaling. In vivo ω-3 epoxides supplementation attenuates the progression of pulmonary hypertension in several animal models. Furthermore, whole-exome sequencing for patients with pulmonary arterial hypertension identifies two candidate pathogenic variants of Pafah2. Our findings support that the PAF-AH2-ω-3 epoxide production axis could be a promising therapeutic target for pulmonary hypertension.

Pulmonary hypertension is a fatal disease that causes right heart failure due to pulmonary artery stenosis. Here, the authors find that ω-3 epoxides produced by the phospholipase PAF-AH2 in mast cells regulate pulmonary vascular remodeling.

Synbiotic Compositions of Bacillus megaterium and Polyunsaturated Fatty Acid Salt Enable Self-Sufficient Production of Specialized Pro-Resolving Mediators

Specialized pro-resolving mediators (SPM) have emerged as crucial lipid mediators that confer the inflammation-resolving effects of omega-3 polyunsaturated fatty acids (n-3 PUFA). Importantly, SPM biosynthesis is dysfunctional in various conditions, which may explain the inconclusive efficacy data from n-3 PUFA interventions. To overcome the limitations of conventional n-3 PUFA supplementation strategies, we devised a composition enabling the self-sufficient production of SPM in vivo. Bacillus megaterium strains were fed highly bioavailable n-3 PUFA, followed by metabololipidomics analysis and bioinformatic assessment of the microbial genomes. All 48 tested Bacillus megaterium strains fed with the n-3 PUFA formulation produced a broad range of SPM and precursors thereof in a strain-specific manner, which may be explained by the CYP102A1 gene polymorphisms that we detected. A pilot study was performed to test if a synbiotic Bacillus megaterium/n-3 PUFA formulation increases SPM levels in vivo. Supplementation with a synbiotic capsule product led to significantly increased plasma levels of hydroxy-eicosapentaenoic acids (5-HEPE, 15-HEPE, 18-HEPE) and hydroxy-docosahexaenoic acids (4-HDHA, 7-HDHA) as well as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in healthy humans. To the best of our knowledge, we report here for the first time the development and in vivo application of a self-sufficient SPM-producing formulation. Further investigations are warranted to confirm and expand these findings, which may create a new class of n-3 PUFA interventions targeting inflammation resolution.

Inflammation and resolution signaling in cardiac repair and heart failure

Unresolved inflammation is a key mediator of advanced heart failure. Especially, damage, pathogen, and lifestyle-associated molecular patterns are the major factors in initiating baseline inflammatory diseases, particularly in cardiac pathology. After a significant cardiac injury like a heart attack, splenic and circulating leukocytes begin a highly optimized sequence of immune cell recruitment (neutrophils and monocytes) to coordinate effective tissue repair. An injured cardiac tissue repair and homeostasis are dependent on clearance of cellular debris where the recruited leukocytes transition from a pro-inflammatory to a reparative program through resolution process. After a cardiac injury, macrophages play a decisive role in cardiac repair through the biosynthesis of endogenous lipid mediators that ensure a timely tissue repair while avoiding chronic inflammation and impaired cardiac repair. However, dysregulation of resolution of inflammation processes due to cardiometabolic defects (obesity, hypertension, and diabetes), aging, or co-medication(s) lead to impaired cardiac repair. Hence, the presented review demonstrates the fundamental role of leukocytes, in particular macrophages orchestrate the inflammation and resolution biology, focusing on the biosynthesis of specialized lipid mediators in cardiac repair and heart failure. This work was supported by research funds from National Institutes of Health (AT006704, HL132989, and HL144788) to G.V.H. The authors acknowledges the use of Servier Medical Art image bank and Biorender that is used to create schematic Figures 1–3.

Synergistic anti-inflammatory effects of graphene oxide quantum dots and trans-10-hydroxy-2-decenoic acid on LPS-stimulated RAW 264.7 macrophage cells

Graphene oxide quantum dots (GOQDs) have attracted substantial attention in numerous fields due to their unique physicochemical properties. However, their nanotoxicity and potential for use in biomedicine still require further study. In this work, the effects of GOQD and trans- 10-hydroxy-2-decenoic acid (10-HDA) cotreatment on the immune function of macrophages (RAW264.7 cells) were investigated. In particular, LC/MS-based metabolomics was performed to evaluate the effects of GOQDs on the metabolism of LPS-stimulated macrophages. Herein, we fabricated GOQDs with good dispersibility and a uniform size distribution of approximately 7 nm using a polyimide-pyrolyzed carbon film as the working electrode, a high-voltage graphite electrode as the cathode, and H₂O₂ as the oxidant. The GOQDs entered the macrophages and emitted green fluorescence under UV irradiation. Cotreatment with GOQDs and 10-HDA induced RAW 264.7 cell proliferation. GOQDs promoted the anti-inflammatory effect of 10-HDA on LPS-stimulated RAW264.7 cells and attenuated the secretion of TNF-α, IL-6, and IL-1β. The metabolites in RAW264.7 cells treated with GOQDs were significantly different from those in RAW264.7 cells treated with LPS. The enrichment analysis showed that treatment with GOQDs interfered with amino acid metabolism, and lipid metabolism. Our results demonstrate the role of GOQDs in macrophages and provide a basis for their further application in biomedical fields.

Free fatty acid receptor 4 responds to endogenous fatty acids to protect the heart from pressure overload

AIMS

Free fatty acid receptor 4 (Ffar4) is a G-protein-coupled receptor for endogenous medium-/long-chain fatty acids that attenuates metabolic disease and inflammation. However, the function of Ffar4 in the heart is unclear. Given its putative beneficial role, we hypothesized that Ffar4 would protect the heart from pathologic stress.

METHODS AND RESULTS

In mice lacking Ffar4 (Ffar4KO), we found that Ffar4 is required for an adaptive response to pressure overload induced by transverse aortic constriction (TAC), identifying a novel cardioprotective function for Ffar4. Following TAC, remodelling was worsened in Ffar4KO hearts, with greater hypertrophy and contractile dysfunction. Transcriptome analysis 3-day post-TAC identified transcriptional deficits in genes associated with cytoplasmic phospholipase A2α signalling and oxylipin synthesis and the reduction of oxidative stress in Ffar4KO myocytes. In cultured adult cardiac myocytes, Ffar4 induced the production of the eicosapentaenoic acid (EPA)-derived, pro-resolving oxylipin 18-hydroxyeicosapentaenoic acid (18-HEPE). Furthermore, the activation of Ffar4 attenuated cardiac myocyte death from oxidative stress, while 18-HEPE rescued Ffar4KO myocytes. Systemically, Ffar4 maintained pro-resolving oxylipins and attenuated autoxidation basally, and increased pro-inflammatory and pro-resolving oxylipins, including 18-HEPE, in high-density lipoproteins post-TAC. In humans, Ffar4 expression decreased in heart failure, while the signalling-deficient Ffar4 R270H polymorphism correlated with eccentric remodelling in a large clinical cohort paralleling changes observed in Ffar4KO mice post-TAC.

CONCLUSION

Our data indicate that Ffar4 in cardiac myocytes responds to endogenous fatty acids, reducing oxidative injury, and protecting the heart from pathologic stress, with significant translational implications for targeting Ffar4 in cardiovascular disease.

Qualitative and Quantitative Effects of Fatty Acids Involved in Heart Diseases

Fatty acids (FAs) have structural and functional diversity. FAs in the heart are closely associated with cardiac function, and their qualitative or quantitative abnormalities lead to the onset and progression of cardiac disease. FAs are important as an energy substrate for the heart, but when in excess, they exhibit cardio-lipotoxicity that causes cardiac dysfunction or heart failure with preserved ejection fraction. FAs also play a role as part of phospholipids that compose cell membranes, and the changes in mitochondrial phospholipid cardiolipin and the FA composition of plasma membrane phospholipids affect cardiomyocyte survival. In addition, FA metabolites exert a wide variety of bioactivities in the heart as lipid mediators. Recent advances in measurement using mass spectrometry have identified trace amounts of n-3 polyunsaturated fatty acids (PUFAs)-derived bioactive metabolites associated with heart disease. n-3 PUFAs have a variety of cardioprotective effects and have been shown in clinical trials to be effective in cardiovascular diseases, including heart failure. This review outlines the contributions of FAs to cardiac function and pathogenesis of heart diseases from the perspective of three major roles and proposes therapeutic applications and new medical perspectives of FAs represented by n-3 PUFAs.

Cardioprotective Effects of n-3 Polyunsaturated Fatty Acids: Orchestration of mRNA Expression, Protein Phosphorylation, and Lipid Metabolism in Pressure Overload Hearts

Background: Pressure overload can result in dilated cardiomyopathy. The beneficial effects of n-3 polyunsaturated fatty acids (n-3 PUFAs) on heart disorders have been widely recognized. However, the molecular mechanisms underlying their protective effects against cardiomyopathy remain unclear. Methods: Pressure overload in mice induced by 8 weeks of transverse aortic constriction was used to induce dilated cardiomyopathy. A transgenic fat-1 mouse model carrying the n-3 fatty acid desaturase gene fat-1 gene from Caenorhabditis elegans was used to evaluate the mechanism of n-3 PUFAs in this disease. Echocardiography, transmission electron microscopy, and histopathological analyses were used to evaluate the structural integrity and function in pressure overloaded fat-1 hearts. mRNA sequencing, label-free phosphoprotein quantification, lipidomics, Western blotting, RT-qPCR, and ATP detection were performed to examine the effects of n-3 PUFAs in the heart. Results: Compared with wild-type hearts, left ventricular ejection fraction was significantly improved (C57BL/6J [32%] vs. fat-1 [53%]), while the internal diameters of the left ventricle at systole and diastole were reduced in the fat-1 pressure overload hearts. mRNA expression, protein phosphorylation and lipid metabolism were remodeled by pressure overload in wild-type and fat-1 hearts. Specifically, elevation of endogenous n-3 PUFAs maintained the phosphorylation states of proteins in the subcellular compartments of sarcomeres, cytoplasm, membranes, sarcoplasmic reticulum, and mitochondria. Moreover, transcriptomic analysis predicted that endogenous n-3 PUFAs restored mitochondrial respiratory chain function that was lost in the dilated hearts, and this was supported by reductions in detrimental oxylipins and protection of mitochondrial structure, oxidative phosphorylation, and ATP production. Conclusions: Endogenous n-3 PUFAs prevents dilated cardiomyopathy via orchestrating gene expression, protein phosphorylation, and lipid metabolism. This is the first study provides mechanistic insights into the cardioprotective effects of n-3 PUFAs in dilated cardiomyopathy through integrated multi-omics data analysis.

Deranged Myocardial Fatty Acid Metabolism in Heart Failure

The heart requires fatty acids to maintain its activity. Various mechanisms regulate myocardial fatty acid metabolism, such as energy production using fatty acids as fuel, for which it is known that coordinated control of fatty acid uptake, β-oxidation, and mitochondrial oxidative phosphorylation steps are important for efficient adenosine triphosphate (ATP) production without unwanted side effects. The fatty acids taken up by cardiomyocytes are not only used as substrates for energy production but also for the synthesis of triglycerides and the replacement reaction of fatty acid chains in cell membrane phospholipids. Alterations in fatty acid metabolism affect the structure and function of the heart. Recently, breakthrough studies have focused on the key transcription factors that regulate fatty acid metabolism in cardiomyocytes and the signaling systems that modify their functions. In this article, we reviewed the latest research on the role of fatty acid metabolism in the pathogenesis of heart failure and provide an outlook on future challenges.

Specialized Proresolving Mediators in Symptomatic Women With Coronary Microvascular Dysfunction (from the Women's Ischemia Trial to Reduce Events in Nonobstructive CAD [WARRIOR] Trial)

Resolvins and maresins, members of the specialized proresolving mediator (SPM) family, are omega-3 fatty acid-derived lipid mediators that attenuate inflammation. We hypothesized that they play a role in the pathophysiology of coronary microvascular dysfunction (CMD) in women with ischemia and no obstructive coronary disease. In a pilot study, we measured the D-series resolvins (D1, D2, D3, and D5), resolvin E1, maresin 1, docosahexaenoic acid, eicosapentaenoic acid (precursor of resolvin E1), and 18-hydroxyeicosapentaenoic acid by mass spectrometry in the peripheral blood of 31 women enrolled in the Women's Ischemia Trial to Reduce Events in Nonobstructive CAD (WARRIOR) trial who had confirmed CMD assessed by coronary flow reserve. We compared SPM levels with 12 gender and age-matched reference subjects. Compared with the reference subject group, those with CMD had significantly lower plasma concentrations of resolvin D1 and maresin 1 and significantly higher levels of docosahexaenoic acid and 18-hydroxyeicosapentaenoic acid. In conclusion, insufficient or ineffective SPM production may play a role in the pathophysiology of CMD. If our results are validated in a larger cohort, omega-3 fatty acid supplementation could be tested as a novel treatment for these patients.

E-series resolvin metabolome, biosynthesis and critical role of stereochemistry of specialized pro-resolving mediators (SPMs) in inflammation-resolution: Preparing SPMs for long COVID-19, human clinical trials, and targeted precision nutrition

The COVID-19 pandemic has raised international awareness of the importance of rigorous scientific evidence and the havoc caused by uncontrolled excessive inflammation. Here we consider the evidence on whether the specialized pro-resolving mediators (SPMs) are ready to meet this challenge as well as targeted metabololipidomics of the resolution-inflammation metabolomes. Specific stereochemical mechanisms in the biosynthesis of SPMs from omega-3 essential fatty acids give rise to unique local-acting lipid mediators. SPMs possess stereochemically defined potent bioactive structures that are high-affinity ligands for cognate G protein-coupled surface receptors that evoke the cellular responses required for efficient resolution of acute inflammation. The SPMs biosynthesized from the major omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are coined Resolvins (resolution phase interaction products; E series and D-series), Protectins and Maresins (macrophage mediators in resolving inflammation). Their biosynthesis and stereochemical assignments are established and confirmed (>1,441 resolvin publications in PubMed.gov) as well as their functional roles on innate immune cells and adaptive immune cells (both lymphocyte T-cell subsets and B-cells). The resolution of a protective acute inflammatory response is governed mainly by phagocytes that actively clear apoptotic cells, debris, blood clots and pathogens. These resolution phase functions of the acute inflammatory response are enhanced by SPMs, which together prepare the inflammatory loci for homeostasis and stimulate tissue regeneration via activating stem cells and the biosynthesis of novel cys-SPMs (e.g. MCTRs, PCTRs and RCTRs). These cys-SPMs also activate regeneration, are organ protective and stimulate resolution of local inflammation. Herein, we review the biosynthesis and functions of the E-series resolvins, namely resolvin E1 (the first n-3 resolvin identified), resolvin E2, resolvin E3 and resolvin E4 biosynthesized from their precursor eicosapentaenoic acid (EPA), and the critical role of total organic synthesis in confirming SPM complete stereochemistry, establishing their potent functions in resolution of inflammation, and novel structures. The physical properties of each biologically derived SPM, i.e., ultra-violet (UV) absorbance, chromatographic behavior, and tandem mass spectrometry (MS2) fragmentation, were matched to SPMs biosynthesized and prepared by stereospecific total organic synthesis. We briefly review this approach, also used with the endogenous D-series resolvins, protectins and maresins confirming their potent functions in resolution of inflammation, that paves the way for their rigorous evaluation in human tissues and clinical trials. The assignment of complete stereochemistry for each of the E and D series Resolvins, Protectins and Maresins was a critical and required step that enabled human clinical studies as in SPM profiling in COVID-19 infections and experimental animal disease models that also opened the promise of resolution physiology, resolution pharmacology and targeted precision nutrition as new areas for monitoring health and disease mechanisms.

Feeding mice a diet high in oxidized linoleic acid metabolites does not alter liver oxylipin concentrations

The oxidation of dietary linoleic acid (LA) produces oxidized LA metabolites (OXLAMs) known to regulate multiple signaling pathways in vivo. Recently, we reported that feeding OXLAMs to mice resulted in liver inflammation and apoptosis. However, it is not known whether this is due to a direct effect of OXLAMs accumulating in the liver, or to their degradation into bioactive shorter chain molecules (e.g. aldehydes) that can provoke inflammation and related cascades. To address this question, mice were fed a low or high LA diet low in OXLAMs, or a low LA diet supplemented with OXLAMs from heated corn oil (high OXLAM diet). Unesterified oxidized fatty acids (i.e. oxylipins), including OXLAMs, were measured in liver after 8 weeks of dietary intervention using ultra-high pressure liquid chromatography coupled to tandem mass-spectrometry. The high OXLAM diet did not alter liver oxylipin concentrations compared to the low LA diet low in OXLAMs. Significant increases in several omega-6 derived oxylipins and reductions in omega-3 derived oxylipins were observed in the high LA dietary group compared to the low LA group. Our findings suggest that dietary OXLAMs do not accumulate in liver, and likely exert pro-inflammatory and pro-apoptotic effects via downstream secondary metabolites.

Imeglimin prevents heart failure with preserved ejection fraction by recovering the impaired unfolded protein response in mice subjected to cardiometabolic stress

The pathogenesis of heart failure with preserved ejection fraction (HFpEF) in obese diabetic patients has been implicated in metainflammation. Increased expression of inducible nitric oxide synthase (iNOS) and dysfunction of the unfolded protein response (UPR), especially inositol-requiring enzyme 1α-X-box binding protein 1 (IRE1α-Xbp1s) signaling in the heart, have been associated with HFpEF. We investigated the effect of imeglimin, a potential new treatment for type 2 diabetes, on the pathogenesis of HFpEF. We induced obesity, impaired glucose tolerance, and cardiac hypertrophy with fibrosis, fat accumulation, and diastolic dysfunction in wild-type mice with a high-fat diet (HFD) and the nitric oxide synthase (NOS) inhibitor l-NAME for 16 weeks. Treatment with imeglimin starting at 10 weeks not only improved their abnormal systemic glucose metabolism and visceral obesity but also their cardiac abnormalities. We found that imeglimin suppressed the upregulation of iNOS, and restored the expression of Xbp1s and the expression of the E3 ubiquitin ligase STIP1 homology and U-box-containing protein 1 (STUB1), which is responsible for the degradation of Forkhead box protein O1 (FoxO1), a direct transcriptional target of Xbp1s. It also suppressed the excessive transcriptional activity of FoxO1, which is located downstream of Xbp1s and is involved in the form development of HFpEF and cardiac adipogenesis. Imeglimin also restored the expression of Glutathione peroxidase 4 (GPX4), which protects cells against excess lipid peroxidation and governs a novel form of programmed cell death, called ferroptosis.

Quantitative analysis of n-3 polyunsaturated fatty acids and their metabolites by chemical isotope labeling coupled with liquid chromatography - mass spectrometry

n-3 polyunsaturated fatty acids (PUFAs) and their metabolites play the crucial role in a wide range of physiologic and pathologic processes, including cardiovascular, neurodegenerative diseases, and inflammation-associated disorders. However, the quantitative analysis of n-3 PUFAs and their metabolites, oxylipins, is obstructed by high structural similarity, poor ionization efficiency and low abundance. In this study, a sensitive method was developed to quantify 28 n-3 PUFAs/oxylipins using chemical isotope labeling coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Standards labeled with cholamine-d₉ were used as one-to-one internal standards to achieve accurate quantification. The cholamine-d₀-derivatized biological samples were mixed with cholamine d₉-labeled standards for LC-MS/MS with multiple reaction monitoring. After cholamine derivatization, both MS sensitivity and chromatographic performance of n-3 PUFAs/oxylipins were substantially improved. Furthermore, the relationship between retention time and substituent position of regioisomers, and their fragmentation patterns were investigated, which may facilitate the identification of unknown oxylipins. Additionally, the developed method was applied to quantify the target n-3 PUFAs/oxylipins in serum and brain tissue from fish oil-supplemented mice, which exhibited its great potential and practicability. Collectively, this sensitive and reliable method may facilitate the elucidation of the roles of n-3 PUFAs/oxylipins in the physiological and pathological processes.

Deletion of Alox15 improves kidney dysfunction and inhibits fibrosis by increased PGD2 in the kidney

BACKGROUND

Lipid-metabolizing enzymes and their metabolites affect inflammation and fibrosis, but their roles in chronic kidney disease (CKD) have not been completely understood.

METHODS

To clarify their role in CKD, we measured the mRNA levels of major lipid-metabolizing enzymes in 5/6 nephrectomized (Nx) kidneys of C57BL/6 J mice. Mediator lipidomics was performed to reveal lipid profiles of CKD kidneys.

RESULTS

In 5/6 Nx kidneys, both mRNA and protein levels of Alox15 were higher when compared with those in sham kidneys. With respect to in situ hybridization, the mRNA level of Alox15 was higher in renal tubules of 5/6 Nx kidneys. To examine the role of Alox15 in CKD pathogenesis, we performed 5/6 Nx on Alox15-/- mice. Alox15-/- CKD mice exhibited better renal functions than wild-type mice. Interstitial fibrosis was also inhibited in Alox15-/- CKD mice. Mediator lipidomics revealed that Alox15-/- CKD mouse kidneys had significantly higher levels of PGD2 than the control. To investigate the effects of PGD2 on renal fibrosis, we administered PGD2 to TGF-β1-stimulated NRK-52E cells and HK-2 cells, which lead to a dose-dependent suppression of type I collagen and αSMA in both cell lines.

CONCLUSION

Increased PGD2 in Alox15-/- CKD mouse kidneys could inhibit fibrosis, thereby resulting in CKD improvement. Thus, Alox15 inhibition and PGD2 administration may be novel therapeutic targets for CKD.

Endogenous conversion of n-6 to n-3 polyunsaturated fatty acids facilitates the repair of cardiotoxin-induced skeletal muscle injury in fat-1 mice

In this study, we investigated the beneficial effects of high endogenous levels of n-3 polyunsaturated fatty acids (PUFAs) on skeletal muscle repair and regeneration using a mouse cardiotoxin (CTX, 20 μM/200 μL) -induced gastrocnemius muscle injury model. Transgenic fat-1 mice expressing the Caenorhabditis elegans fat-1 gene, encoding n-3 fatty acid desaturase, showed higher n-3 PUFA levels and lower n-6/n-3 PUFA ratios in gastrocnemius muscle tissues. Hematoxylin and eosin and Masson’s trichrome staining of gastrocnemius sections revealed increased muscle fiber size and reduced fibrosis in fat-1 mice on days 7 and 14 after CTX injections. Gastrocnemius muscle tissues from fat-1 mice showed reduced inflammatory responses and increased muscle fiber regeneration reflecting enhanced activation of satellite cells on day 3 after cardiotoxin injections. Gastrocnemius muscle tissues from cardiotoxin-treated fat-1 mice showed reduced levels of pro-apoptotic proteins (Caspase 3 and Bax) and increased levels of anti-apoptotic proteins (Bcl-2 and Survivin). Moreover, eicosapentaenoic acid (EPA) reduced the incidence of apoptosis among cardiotoxin-treated C2C12 mouse myoblasts. These findings demonstrate that higher endogenous n-3 PUFA levels in fat-1 mice enhances skeletal muscle repair and regeneration following cardiotoxin-induced injury.

A New E-Series Resolvin: RvE4 Stereochemistry and Function in Efferocytosis of Inflammation-Resolution

The resolution of the acute inflammatory response is governed by phagocytes actively clearing apoptotic cells and pathogens. Biosynthesis of the specialized pro-resolving mediators (SPMs) is pivotal in the resolution of inflammation via their roles in innate immune cells. Resolvin E4 (RvE4: 5S,15S-dihydroxy-eicosapentaenoic acid) is a newly uncovered member of the E-series resolvins biosynthesized from eicosapentaenoic acid (EPA) recently elucidated in physiologic hypoxia. This new resolvin was termed RvE4 given its ability to increase efferocytosis of apoptotic cells by macrophages. Herein, we report on the total organic synthesis of RvE4 confirming its unique structure, complete stereochemistry assignment and function. This synthetic RvE4 matched the physical properties of biogenic RvE4 material, i.e. ultra-violet (UV) absorbance, chromatographic behavior, and tandem mass spectrometry (MS²) fragmentation, as well as bioactivity. We confirmed RvE4 potent responses with human M2 macrophage efferocytosis of human apoptotic neutrophils and senescent red blood cells. Together, these results provide direct evidence for the assignment of the complete stereochemistry of RvE4 as 5S,15S-dihydroxy-6E,8Z,11Z,13E,17Z-eicosapentaenoic acid and its bioactions in human phagocyte response.

High Plasma Docosahexaenoic Acid Associated to Better Prognoses of Patients with Acute Decompensated Heart Failure with Preserved Ejection Fraction

The clinical relevance of polyunsaturated fatty acids (PUFAs) in heart failure remains unclear. The aim of this study was to investigate the association between PUFA levels and the prognosis of patients with heart failure with preserved ejection fraction (HFpEF). This retrospective study included 140 hospitalized patients with acute decompensated HFpEF (median age 84.0 years, 42.9% men). The patients' nutritional status was assessed, using the geriatric nutritional risk index (GNRI), and their plasma levels of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA), and dihomo-gamma-linolenic acid (DGLA) were measured before discharge. The primary outcome was all-cause mortality. During a median follow-up of 23.3 months, the primary outcome occurred in 37 patients (26.4%). A Kaplan-Meier analysis showed that lower DHA and DGLA levels, but not EPA or AA levels, were significantly associated with an increase in all-cause death (log-rank; p < 0.001 and p = 0.040, respectively). A multivariate Cox regression analysis also revealed that DHA levels were significantly associated with the incidence of all-cause death (HR: 0.16, 95% CI: 0.06-0.44, p = 0.001), independent of the GNRI. Our results suggest that low plasma DHA levels may be a useful predictor of all-cause mortality and potential therapeutic target in patients with acute decompensated HFpEF.

Role of polyunsaturated fatty acids in ischemic stroke - A perspective of specialized pro-resolving mediators

Polyunsaturated fatty acids (PUFAs) have been proposed as beneficial for cardiovascular health. However, results from both epidemiological studies and clinical trials have been inconsistent, whereas most of the animal studies showed promising benefits of PUFAs in the prevention and treatment of ischemic stroke. In recent years, it has become clear that PUFAs are metabolized into various types of bioactive derivatives, including the specialized pro-resolving mediators (SPMs). SPMs exert multiple biofunctions, such as to limit excessive inflammatory responses, regulate lipid metabolism and immune cell functions, decrease production of pro-inflammatory factors, increase anti-inflammatory mediators, as well as to promote tissue repair and homeostasis. Inflammation has been recognised as a key contributor to the pathophysiology of acute ischemic stroke. Owing to their potent pro-resolving actions, SPMs are potential for development of novel anti-stroke therapy. In this review, we will summarize current knowledge of epidemiological studies, basic research and clinical trials concerning PUFAs in stroke prevention and treatment, with special attention to SPMs as the unsung heroes behind PUFAs.

Exploiting oxidized lipids and the lipid-binding GPCRs against cardiometabolic diseases

Lipids govern vital cellular processes and drive physiological changes in response to different pathological or environmental cues. Lipid species can be roughly divided into structural and signalling lipids. The former is essential for membrane composition, while the latter are usually oxidized lipids. These mediators provide beneficial effects against cardiometabolic diseases (CMDs), including fatty-liver diseases, atherosclerosis, thrombosis, obesity, and Type 2 diabetes. For instance, several oxylipins were recently found to improve glucose homeostasis, increase insulin secretion, and inhibit platelet aggregation, while specialized pro-resolving mediators (SPMs) are able to ameliorate CMD by shaping the immune system. These lipids act mainly by stimulating GPCRs. In this review, we provide an updated and comprehensive overview of the current state of the literature on signalling lipids in the context of CMD. We also highlight the network encompassing the lipid-modifying enzymes and the lipid-binding GPCRs, as well as their interactions in health and disease.

EPA and DHA differentially modulate monocyte inflammatory response in subjects with chronic inflammation in part via plasma specialized pro-resolving lipid mediators: A randomized, double-blind, crossover study

BACKGROUND AND AIMS

The independent effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on chronic inflammation through their downstream lipid mediators, including the specialized pro-resolving lipid mediators (SPM), remain unstudied. Therefore, we compared the effects of EPA and DHA supplementation on monocyte inflammatory response and plasma polyunsaturated fatty acids (PUFA) SPM lipidome.

METHODS

After a 4-week lead-in phase (baseline), 9 men and 12 postmenopausal women (50-75 years) with chronic inflammation received two phases of 10-week supplementation with 3 g/day EPA and DHA in a random order, separated by a 10-week washout.

RESULTS

Compared with baseline, EPA and DHA supplementation differently modulated LPS-stimulated monocyte cytokine expression. EPA lowered TNFA (p < 0.001) whereas DHA reduced TNFA (p < 0.001), IL6 (p < 0.02), MCP1 (p < 0.03), and IL10 (p < 0.01). DHA lowered IL10 expression relative to EPA (p = 0.03). Relative to baseline, EPA, but not DHA, decreased the ratios of TNFA/IL10 and MCP1/IL10 (both p < 0.01). EPA and DHA also significantly changed plasma PUFA SPM lipidome by replacing n-6 AA derivatives with their respective derivatives including 18-hydroxy-EPA (+5 fold by EPA) and 17- and 14-hydroxy-DHA (+3 folds by DHA). However, DHA showed a wider effect than EPA by also significantly increasing EPA derivatives and DPA-derived SPM at a greater expense of AA derivatives. Different groups of PUFA derivatives mediated the differential effects of EPA and DHA on monocyte cytokine expression.

CONCLUSIONS

EPA and DHA had distinct effects on monocyte inflammatory response with a broader effect of DHA in attenuating pro-inflammatory cytokines. These differential effects were potentially mediated by different groups of PUFA derivatives, suggesting immunomodulatory activities of SPM and their intermediates.

Acute injection of a DHA triglyceride emulsion after hypoxic-ischemic brain injury in mice increases both DHA and EPA levels in blood and brain✰

We recently reported that acute injection of docosahexaenoic acid (DHA) triglyceride emulsions (tri-DHA) conferred neuroprotection after hypoxic-ischemic (HI) injury in a neonatal mouse stroke model. We showed that exogenous DHA increased concentrations of DHA in brain mitochondria as well as DHA-derived specialized pro-resolving mediator (SPM) levels in the brain. The objective of the present study was to investigate the distribution of emulsion particles and changes in plasma lipid profiles after tri-DHA injection in naïve mice and in animals subjected to HI injury. We also examined whether tri-DHA injection would change DHA- and eicosapentaenoic acid (EPA)-derived SPM levels in the brain. To address this, neonatal (10-day-old) naïve and HI mice were injected with radiolabeled tri-DHA emulsion (0.375 g tri-DHA/kg bw), and blood clearance and tissue distribution were analyzed. Among all the organs assayed, the lowest uptake of emulsion particles was in the brain (<0.4% recovered dose) in both naïve and HI mice, while the liver had the highest uptake. Tri-DHA administration increased DHA concentrations in plasma lysophosphatidylcholine and non-esterified fatty acids. Additionally, treatment with tri-DHA after HI injury significantly elevated the levels of DHA-derived SPMs and monohydroxy-containing DHA-derived products in the brain. Further, tri-DHA administration increased resolvin E2 (RvE2, 5S,18R-dihydroxy-eicosa-6E,8Z,11Z,14Z,16E-pentaenoic acid) and monohydroxy-containing EPA-derived products in the brain. These results suggest that the transfer of DHA through plasma lipid pools plays an important role in DHA brain transport in neonatal mice subjected to HI injury. Furthermore, increases in EPA and EPA-derived SPMs following tri-DHA injection demonstrate interlinked metabolism of these two fatty acids. Hence, changes in both EPA and DHA profile patterns need to be considered when studying the protective effects of DHA after HI brain injury. Our results highlight the need for further investigation to differentiate the effects of DHA from EPA on neuroprotective pathways following HI damage. Such information could contribute to the development of specific DHA-EPA formulations to improve clinical endpoints and modulate potential biomarkers in ischemic brain injury.

Effect of dietary EPA and DHA on murine blood and liver fatty acid profile and liver oxylipin pattern depending on high and low dietary n6-PUFA

The intake of long-chain n3-polyunsaturated fatty acids (PUFA), which are associated with beneficial health effects, is low in the Western diet, while the portion of dietary n6-PUFA and hence the n6/n3-PUFA ratio is high. Strategies to improve the n3-PUFA status are n3-PUFA supplementation and/or lowering n6-PUFA intake. In the present study, mice were fed with two different sunflower oil-based control diets rich in linoleic (n6-high) or oleic acid (n6-low), either with low n3-PUFA content (∼0.02%) as control or with ∼0.6% eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA). The n6-low diet had only little or no effect on levels of arachidonic acid (ARA) and its free oxylipins in liver tissue. Supplementation with EPA or DHA lowered ARA levels with an effect size of n6-high < n6-low. Blood cell %EPA + DHA reached >8% and >11% in n6-high and n6-low groups, respectively. Elevation of EPA levels and EPA derived oxylipins was most pronounced in n6-low groups in liver tissue, while levels of DHA and DHA derived oxylipins were generally unaffected by the background diet. While the n6-low diet alone had no effect on blood and liver tissue ARA levels or n3-PUFA status, a supplementation of EPA or DHA was more effective in combination with an n6-low diet. Thus, supplementation of long-chain n3-PUFA combined with a reduction of dietary n6-PUFA is the most effective way to improve the endogenous n3-PUFA status.

Quantitative Profiling of Oxylipins in Acute Experimental Intracerebral Hemorrhage

Oxylipins are a series of bioactive lipid metabolites derived from polyunsaturated fatty acids that are involved in cerebral homeostasis and the development of intracerebral hemorrhage (ICH). However, comprehensive quantification of the oxylipin profile in ICH remains unknown. Therefore, an ICH mouse model was constructed and liquid chromatography tandem mass spectrometry was then performed to quantify the change in oxylipins in ICH. The expression of the oxylipin relative enzymes was also reanalyzed based on RNA-seq data from our constructed ICH dataset. A total of 58 oxylipins were quantifiable and the levels of 17 oxylipins increased while none decreased significantly in the first 3 days following ICH. The most commonly increased oxylipins in ICH were derived from AA (10/17) and EPA (4/17) followed by LA (2/17) and DHA (1/17). 18-HEPE from EPA was the only oxylipin that remained significantly increased from 0.5 to 3 days following ICH. Furthermore, 14 of the increased oxylipins reached a peak level on the first day of ICH, and soon decreased while five oxylipins (PGJ2, 15-oxo-ETE, 12-HEPE, 18-HEPE, and 5-oxo-ETE) had increased 3 days after ICH suggesting that the profile shifted with the progression of ICH. In our constructed RNA-seq dataset based on ICH rats, 90 oxylipin relative molecules were detected except for COX. Among these, Cyp4f18, Cyp1b1, Cyp2d3, Cyp2e1, Cyp1a1, ALOX5AP, and PLA2g4a were found up-regulated and Cyp26b1 was found to decrease in ICH. In addition, there was no significant change in sEH in ICH. This study provides fundamental data on the profile of oxylipins and their enzymes in ICH. We found that the profile shifted as the progression of ICH and the metabolism of arachidonic acid and eicosapentaenoic acid was highly affected in ICH, which will help further studies explore the functions of oxylipins in ICH.

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.