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

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.

Dietary Fish Hydrolysate Improves Memory Performance Through Microglial Signature Remodeling During Aging

Brain aging is characterized by a chronic low-grade inflammation, which significantly impairs cognitive function. Microglial cells, the immunocompetent cells of the brain, present a different phenotype, switching from a homeostatic signature (M0) to a more reactive phenotype called “MGnD” (microglial neurodegenerative phenotype), leading to a high production of pro-inflammatory cytokines. Furthermore, microglial cells can be activated by age-induced gut dysbiosis through the vagus nerve or the modulation of the peripheral immune system. Nutrients, in particular n-3 long chain polyunsaturated fatty acids (LC-PUFAs) and low molecular weight peptides, display powerful immunomodulatory properties, and can thus prevent age-related cognitive decline. The objective of this study was to investigate the effects of n-3 LC-PUFAs and low molecular weight peptides contained in a marine by-product-derived hydrolysate on microglial phenotypes and intestinal permeability and their consequences on cognition in mice. We demonstrated that the hydrolysate supplementation for 8 weeks prevented short- and long-term memory decline during aging. These observations were linked to the modulation of microglial signature. Indeed, the hydrolysate supplementation promoted homeostatic microglial phenotype by increasing TGF-β1 expression and stimulated phagocytosis by increasing Clec7a expression. Moreover, the hydrolysate supplementation promoted anti-inflammatory intestinal pathway and tended to prevent intestinal permeability alteration occurring during aging. Therefore, the fish hydrolysate appears as an interesting candidate to prevent cognitive decline during aging.

Dietary omega-3 polyunsaturated fatty acids and fish intake and risk of age-related macular degeneration

BACKGROUND & AIMS

Epidemiologic studies are inconsistent regarding the association of dietary omega-3 polyunsaturated fatty acids (PUFA) and/or fish intake with risk of age-related macular degeneration (AMD) incidence and progression. The objective was to determine these associations by conducting a meta-analysis of available studies.

METHODS

Three electronic databases were searched for studies that quantified dietary omega-3 PUFA and/or fish intake from inception to December 2020 without language restriction. Three investigators independently assessed for inclusion and extracted data. Study-specific risk estimates were combined using random-effects model. Potential dose-response associations were explored with the use of generalized least-squares trend estimation.

RESULTS

21 studies were included in the meta-analysis. Higher dietary intakes of omega-3 PUFA was significantly associated with 14% (relative risk [RR]: 0.86, 95% confidence interval [CI]: 0.77, 0.96) and 29% (RR: 0.71, 95% CI: 0.55, 0.91) lower risk of early and late AMD, respectively. The dose-response analysis showed a 6% and 22% decrease in the risk of early and late AMD for each additional 1  g/d omega-3 PUFA intake. For individual omega-3 PUFA, the intake of eicosapentaenoic acid and docosahexaenoic acid was inversely associated with lower AMD risk, whereas no association was found for the alpha-linolenic acid. Consistent inverse associations were also found between fish intake and AMD. The pooled RRs comparing extreme categories of fish intake were 0.79 (95% CI: 0.70, 0.90) and 0.71 (95% CI: 0.60, 0.85) for early and late AMD risk, respectively. Every 15 g/d of fish consumption was associated with 13% and 14% lower early and late AMD. In addition, fish intake was associated with a significantly reduced risk of AMD progression (RR: 0.73, 95% CI: 0.53, 1.00).

CONCLUSIONS

A high intake of dietary omega-3 PUFA or fish was associated with a reduced risk of developing of AMD, which further supports that consumption of omega-3 PUFA-rich foods may be a new avenue nutritional approach to preventing AMD.

Process optimization and characterization of arachidonic acid oil degumming using ultrasound-assisted enzymatic method

Ultrasound assisted enzymatic method was applied to the degumming of arachidonic acid (ARA) oil produced by Mortierella alpina. The conditions of degumming process were optimized by response surface methodology with Box- Behnken design. A dephosphorization rate of 98.82% was achieved under optimum conditions of a 500 U/kg of Phospholipase A₁ (PLA₁) dosage, 2.8 mL/100 g of water volume, 120 min of ultrasonic time, and 135 W of ultrasonic power. The phosphorus content of ultrasonic assisted enzymatic degumming oil (UAEDO) was 4.79 mg/kg, which was significantly lower than that of enzymatic degumming oil (EDO, 17.98 mg/kg). Crude Oil (CO), EDO and UAEDO revealed the similar fatty acid compositions, and ARA was dominated (50.97 ~ 52.40%). The oxidation stability of UAEDO was equivalent to EDO and weaker than CO, while UAEDO presented the strongest thermal stability, followed by EDO and CO. Furthermore, aldehydes, acids and alcohols were identified the main volatile flavor components for the three oils. The proportions of major contributing components such as hexanal, nonanal, (E)-2-nonanal, (E, E)-2,4-decadienal, (E)-2-nonenal and aldehydes in UAEDO and EDO were all lower than CO. Overall, Ultrasound assisted enzymatic degumming proved to be an efficient and superior method for degumming of ARA oil.

The effect of omega-3 fatty acids on a biomarker of head trauma in NCAA football athletes: a multi-site, non-randomized study

Background

American-style football (ASF) athletes are at risk for cardiovascular disease (CVD) and exhibit elevated levels of serum neurofilament light (Nf-L), a biomarker of axonal injury that is associated with repetitive head impact exposure over the course of a season of competition. Supplementation with the w-3 fatty acid (FA) docosahexaenoic acid (DHA) attenuates serum Nf-L elevations and improves aspects of CVD, such as the omega-3 index (O3I). However, the effect of combining the w-3 FA eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA) with DHA on, specifically, serum Nf-L in ASF athletes is unknown. Therefore, this study assessed the effect of supplemental w-3 FA (EPA+DPA+DHA) on serum Nf-L, plasma w-3 FAs, the O3I, and surrogate markers of inflammation over the course of a season.

Methods

A multi-site, non-randomized design, utilizing two American football teams was employed. One team (n = 3 1) received supplementation with a highly bioavailablew-3 FA formulation (2000mg DHA, 560mg EPA, 320mg DPA, Mindset®, Struct Nutrition, Missoula, MT) during pre-season and throughout the regular season, while the second team served as the control (n = 35) and did not undergo supplementation. Blood was sampled at specific times throughout pre- and regular season coincident w ith changes in intensity, physical contact, and changes in the incidence and severity of head impacts. Group differences were determined via a mixed-model between-within subjects ANOVA. Effect sizes were calculated using Cohen’s dfor all between-group differences. Significance was set a priori at p< .05.

Results

Compared to the control group, ASF athletes in the treatment group experienced large increases in plasma EPA (p < .001, d = 1.71) and DHA (p < .001, d = 2.10) which contributed to increases in the O3I (p < .001, d = 2.16) and the EPA:AA ratio (p = .001, d = 0.83) and a reduction in the w-6: w-3 ratio (p < .001, d = 1.80). w-3 FA supplementation attenuated elevations in Nf-L (p = .024). The control group experienced a significant increase in Nf-L compared to baseline at several measurement time points (T2, T3, and T4 [p range < .001 – .005, drange = 0.59-0.85]).

Conclusions

These findings suggest a cardio- and neuroprotective effect of combined EPA+DPA+DHA w-3 FA supplementation in American-style football athletes.

Trial registration

This trial was registered with the ISRCTN registry (ISRCTN90306741).

Bioactive Lipids and Their Derivatives in Biomedical Applications

Lipids, which along with carbohydrates and proteins are among the most important nutrients for the living organism, have a variety of biological functions that can be applied widely in biomedicine. A fatty acid, the most fundamental biological lipid, may be classified by length of its aliphatic chain, and the short-, medium-, and long-chain fatty acids and each have distinct biological activities with therapeutic relevance. For example, short-chain fatty acids have immune regulatory activities and could be useful against autoimmune disease; medium-chain fatty acids generate ketogenic metabolites and may be used to control seizure; and some metabolites oxidized from long-chain fatty acids could be used to treat metabolic disorders. Glycerolipids play important roles in pathological environments, such as those of cancers or metabolic disorders, and thus are regarded as a potential therapeutic target. Phospholipids represent the main building unit of the plasma membrane of cells, and play key roles in cellular signaling. Due to their physical properties, glycerophospholipids are frequently used as pharmaceutical ingredients, in addition to being potential novel drug targets for treating disease. Sphingolipids, which comprise another component of the plasma membrane, have their own distinct biological functions and have been investigated in nanotechnological applications such as drug delivery systems. Saccharolipids, which are derived from bacteria, have endotoxin effects that stimulate the immune system. Chemically modified saccharolipids might be useful for cancer immunotherapy or as vaccine adjuvants. This review will address the important biological function of several key lipids and offer critical insights into their potential therapeutic applications.

Vascepa protects against high-fat diet-induced glucose intolerance, insulin resistance, and impaired β-cell function

Omega-3 fatty acid prescription drugs, Vascepa (≥96% eicosapentaenoic acid [EPA] ethyl ester) and Lovaza (46.5% EPA and 37.5% docosahexaenoic acid ethyl ester) are known therapeutic regimens to treat hypertriglyceridemia. However, their impact on glucose homeostasis, progression to type 2 diabetes, and pancreatic beta cell function are not well understood. In the present study, mice were treated with Vascepa or Lovaza for one week prior to six weeks of high-fat diet feeding. Vascepa but not Lovaza led to reduced insulin resistance, reduced fasting insulin and glucose, and improved glucose intolerance. Vascepa improved beta cell function, reduced liver triglycerides with enhanced expression of hepatic fatty acid oxidation genes, and altered microbiota composition. Vascepa has protective effects on diet-induced insulin resistance and glucose intolerance in mice.

Differential and shared effects of eicosapentaenoic acid and docosahexaenoic acid on serum metabolome in subjects with chronic inflammation

The omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) affect cell function and metabolism, but the differential effects of EPA and DHA are not known. In a randomized, controlled, double-blind, crossover study, we assessed the effects of 10-week supplementation with EPA-only and DHA-only (3 g/d), relative to a 4-week lead-in phase of high oleic acid sunflower oil (3 g/day, defined as baseline), on fasting serum metabolites in 21 subjects (9 men and 12 post-menopausal women) with chronic inflammation and some characteristics of metabolic syndrome. Relative to baseline, EPA significantly lowered the tricarboxylic acid (TCA) cycle intermediates fumarate and α-ketoglutarate and increased glucuronate, UDP-glucuronate, and non-esterified DHA. DHA significantly lowered the TCA cycle intermediates pyruvate, citrate, isocitrate, fumarate, α-ketoglutarate, and malate, and increased succinate and glucuronate. Pathway analysis showed that both EPA and DHA significantly affected the TCA cycle, the interconversion of pentose and glucuronate, and alanine, and aspartate and glutamate pathways (FDR < 0.05) and that DHA had a significantly greater effect on the TCA cycle than EPA. Our results indicate that EPA and DHA exhibit both common and differential effects on cell metabolism in subjects with chronic inflammation and some key aspects of metabolic syndrome.

Effect of omega-3 fatty acids on cardiovascular outcomes: A systematic review and meta-analysis

BACKGROUND

The effects of omega-3 fatty acids (FAs), such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, on cardiovascular outcomes are uncertain. We aimed to determine the effectiveness of omega-3 FAs on fatal and non-fatal cardiovascular outcomes and examine the potential variability in EPA vs. EPA+DHA treatment effects.

METHODS

We searched EMBASE, PubMed, ClinicalTrials.gov, and Cochrane library databases through June 7, 2021. We performed a meta-analysis of 38 randomized controlled trials of omega-3 FAs, stratified by EPA monotherapy and EPA+DHA therapy. We estimated random-effects rate ratios (RRs) with (95% confidence intervals) and rated the certainty of evidence using GRADE. The key outcomes of interest were cardiovascular mortality, non-fatal cardiovascular outcomes, bleeding, and atrial fibrillation (AF). The protocol was registered in PROSPERO (CRD42021227580).

FINDINGS

In 149,051 participants, omega-3 FA was associated with reducing cardiovascular mortality (RR, 0.93 [0.88-0.98]; p = 0.01), non-fatal myocardial infarction (MI) (RR, 0.87 [0.81-0.93]; p = 0.0001), coronary heart disease events (CHD) (RR, 0.91 [0.87-0.96]; p = 0.0002), major adverse cardiovascular events (MACE) (RR, 0.95 [0.92-0.98]; p = 0.002), and revascularization (RR, 0.91 [0.87-0.95]; p = 0.0001). The meta-analysis showed higher RR reductions with EPA monotherapy (0.82 [0.68-0.99]) than with EPA + DHA (0.94 [0.89-0.99]) for cardiovascular mortality, non-fatal MI (EPA: 0.72 [0.62-0.84]; EPA+DHA: 0.92 [0.85-1.00]), CHD events (EPA: 0.73 [0.62-0.85]; EPA+DHA: 0.94 [0.89-0.99]), as well for MACE and revascularization. Omega-3 FA increased incident AF (RR, 1.26 [1.08-1.48]). EPA monotherapy vs. control was associated with a higher risk of total bleeding (RR: 1.49 [1.20-1.84]) and AF (RR, 1.35 [1.10-1.66]).

INTERPRETATION

Omega-3 FAs reduced cardiovascular mortality and improved cardiovascular outcomes. The cardiovascular risk reduction was more prominent with EPA monotherapy than with EPA+DHA.

FUNDING

None.

Sexual dimorphism of monocyte transcriptome in individuals with chronic low-grade inflammation

Sexual dimorphism in the immune system is evidenced by a higher prevalence of autoimmune diseases in women and higher susceptibility to infectious diseases in men. However, the molecular basis of these sex-based differences is not fully understood. We have characterized the transcriptome profiles of peripheral blood monocytes from males and postmenopausal females with chronic low-grade inflammation. We identified 41 sexually differentially expressed genes [adjusted p value (FDR) < 0.1], including genes involved in immune cell activation (e.g., CEACAM1, FCGR2B, and SLAMF7) and antigen presentation (e.g., AIM2, CD1E, and UBA1) with a higher expression in females than males. Moreover, signaling pathways of immune or inflammatory responses, including interferon (IFN) signaling [z-score = 2.45, -log(p) = 3.88], were found to be more upregulated in female versus male monocytes, based on a set of genes exhibiting sex-biased expression (p < 0.03). The contribution of IFN signaling to the sexual transcriptional differences was further confirmed by direct comparisons of the monocyte sex-biased genes with IFN signature genes (ISGs) that were previously curated in mouse macrophages. ISGs showed a greater overlap with female-biased genes than male-biased genes and a higher overall expression in female than male monocytes, particularly for the genes of antiviral and inflammatory responses to IFN. Given the role of IFN in immune defense and autoimmunity, our results suggest that sexual dimorphism in immune functions may be associated with more priming of innate immune pathways in female than male monocytes. These findings highlight the role of sex on the human immune transcriptome.

Effect of lipopolysaccharide on peripheral tissue and hypothalamic expression of metabolic and inflammatory markers in mice fed high-fat diets with distinct 18-carbon fatty acid composition

Physiological and metabolic effects of fatty acids are determined by their degree of saturation and chain length. Effects of 18-carbon fatty acids with various degrees of saturation on inflammatory, oxidative, and neuropeptide gene transcription, especially in the hypothalamus, in response to LPS-induced acute inflammation have not been well studied. We conducted this study to test whether diets with distinct 18-carbon fatty acid differentially affect inflammatory and metabolic response to LPS exposure in the hypothalamus, liver, and muscle tissues. Four experimental diets were fed for 4 weeks to male C57BL/6J mice, and a terminal 4-h lipopolysaccharide (LPS) injection was administered. Diets included a control diet (CON) containing 5.6% kcal fat from lard and 4.4% kcal fat from soybean oil, and three high-fat diets (HFD) containing 25% kcal fat from lard and 20% kcal fat from either shea butter (SHB; saturated fatty acid-rich fat), olive oil (OLO; monounsaturated fatty acid-rich oil), or soybean oil (SBO; polyunsaturated fatty acid-rich fat). Compared to CON, HFD-fed mice had higher weight gain and body fat accumulation. The SBO group had lowest Cpt1b expression in the liver, and OLO group had the lowest Pomc and the highest Lepr expression in the hypothalamus. LPS challenge increased pro-inflammatory cytokine mRNA expression in the brain and peripheral tissues. However, the diets did not exert distinguishable effects on LPS-induced inflammatory responses. Therefore, saturation degree of 18-carbon fatty acids may not play a critical role in their effects on inflammatory and metabolic indicators in response to acute inflammation induced by LPS.

Antioxidant balance in plasma of patients on home parenteral nutrition: A pilot study comparing three different lipid emulsions

BACKGROUND & AIMS

Parenteral nutrition (PN) can supply all essential nutrients to a patient with gastrointestinal insufficiency. However, the sensitivity to lipid peroxidation might increase in those receiving PN, especially home parenteral nutrition (HPN). This study aimed to investigate whether PN affects the antioxidant balance of plasma of HPN patients without comorbidities and whether this balance is influenced by comorbidities and according to the type of lipid emulsion included in the PN.

METHODS

Adult patients on HPN (n = 86) received one of three types of lipid emulsion (based on 1) soyabean oil, 2) olive and soyabean oil or 3) soyabean, coconut, olive and fish oil) in all-in-one mixtures; in addition healthy controls (n = 66) were studied as comparators. HPN patients were classified to the following subgroups: 1) patients without (n = 58) or with (n = 28) comorbidities 2) patients on Intralipid (G_INTRA, n = 53), ClinOleic (G_CLIN, n = 17) or SMOFlipid (G_SMOFn = 16). The activities of total glutathione peroxidase (GSH-Px), selenium dependent glutathione peroxidase (Se-GSHPx) and glutathione S-transferase (GST) in plasma were determined spectrophotometrically. The antioxidant potential of plasma was determined using oxygen radical absorbance capacity (ORAC). The lipid peroxidation marker malondialdehyde (MDA) was analyzed with high performance liquid chromatography.

RESULTS

MDA concentration was the highest in G_INTRA and the lowest in G_SMOF (p < 0.05). G_SMOF also had the highest activity of GSH-Px. No differences in Se-GSHPx, GST and ORAC were observed among G_INTRA, G_CLIN and G_SMOF. Comparing with healthy controls, significantly lower GST (p = 0.0293) and ORAC (p < 0.0001) were observed in the HPN patients. Among all measured parameters only the concentration of MDA was significantly higher in patients with comorbidities compared to those without them. Comorbidities did not influence MDA level in G_INTRA and G_SMOF being still the lowest in G_SMOF (p = 0.0033). In contrast, significantly higher MDA level was observed for G_CLIN in those with vs. without comorbidities (p = 0.0262).

CONCLUSIONS

Patients on HPN have lower antioxidant defenses than healthy controls. The type of lipid emulsion used in HPN affects lipid peroxidation (even after taking into account comorbidities which often involve oxidative stress) being the highest in G_INTRA and the lowest in G_SMOF. Thus, to minimize the risk of oxidative stress, SMOFlipid can be considered in patients in HPN especially for those with comorbidities. ClinOleic can be considered in HPN patients without comorbidities. The observation should be confirmed in larger studies.

The ratio of eicosapentaenoic acid to docosahexaenoic acid as a modulator for the cardio-metabolic effects of omega-3 supplements: A meta-regression of randomized clinical trials

BACKGROUND

A large number of studies have demonstrated the effects of omega- 3 supplements containing mixtures of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), known to favorably affect many modifiable risk factors of coronary heart disease (CHD). These studies have used diverse ratios and doses of EPA and DHA. However, it is not known whether the ratio of EPA to DHA in omega-3 supplements affect their efficacy as modulators for cardiovascular risk factors. This meta-regression aimed to investigate the effect of different ratios of EPA to DHA on risk factors associated with CHD including lipid profile, blood pressure, heart rate, and inflammation.

METHOD

A regression analysis was carried out on 92 clinical trials with acceptable quality (Jadad score ≥ 3) that were previously identified from two databases (PubMed and Cochrane Library).

RESULTS

Data from studies that met the inclusion criteria for this analysis showed that the ratio of EPA to DHA was not associated with lipid profile, diastolic blood pressure, or heart rate. With all studies, the ratio of EPA to DHA was associated with C-reactive protein (CRP) (β = -1.3121 (95 % CI: -1.6610 to -0.9543), that is, the higher the EPA to DHA ratio, the greater the reduction. Using only studies that supplied EPA and DHA in the range of 2 g-6 g, the ratio of EPA to DHA was also associated with CRP (β = -2.10429 and 95 % CI: -3.89963 to -0.30895); that is, an even more pronounced reduction in CRP with a higher EPA to DHA ratio. Systolic blood pressure was only associated with an increasing EPA to DHA ratio in the 2 g-6 g range (β = 5.47129 and 95 % CI: 0.40677-10.53580), that is, a higher EPA to DHA ratio within this dose range, the greater the increase in SBP.

CONCLUSION

Current data suggest that the EPA to DHA ratio only correlates to the modulation of CRP by omega-3 supplementation of EPA and DHA, and SBP in studies that supplemented EPA and DHA in the range of 2 g-6 g, shedding light on potential differential effects of EPA vs. DHA on inflammation and systolic blood pressure.