Docosahexaenoic Acid Phospholipid Research Articles

Green biosynthesis of DHA-phospholipids in tailor-made supersaturated DHA aqueous solution and catalytic mechanism study

Docosahexaenoic acid-phospholipids (DHA-PLs) were prepared via lipase-mediated transesterification of DHA donor and phosphatidylcholine (PC) in a purely aqueous solution. Pre-existing carriers would play the role as “artificial interfaces” to adsorb water-insoluble PC and made them disperse in water. DHA donors were concentrated by a pH-responsive method and presented as supersaturated salt solutions. 153 triacylglycerol lipase structures were analyzed and screened in silico. Transesterification was carried out to further evaluate the six lipase candidates. Lipase B from Candida antarctica (CALB) was the best biocatalyst with 34.8% of DHA incorporation and 80.0% of PLs yields (involving 38.1% PC and 41.9% sn-1 lyso-PC). Toxic organic solvents were avoided. Six possible microunits of our aqueous system consisting of three PLs donors (PC, lyso-PC, sn-glycero-3-PC) and two DHA donors (DHA and DHA salts), were simulated by molecular dynamics (MD) to illustrate the enzymatic mechanism based on diffusional channels, competitive bindings, and enzymatic structures.

APOE e4 dependent deficits in brain DHA phospholipids and mfsd2a in Alzheimer’s disease patients with severe cerebral amyloid angiopathy

AbstractBackgroundThe apolipoprotein E e4 allele (APOE4) is a major risk factor, contributing to vascular pathologies in AD which include CAA, BBB dysfunction and reduced cerebral vascular integrity. The diminished capacity of APOE4 to transport docosahexaenoic acid (DHA), an essential fatty acid required for the structural and functional maintenance and vascular integrity of the brain, could also contribute to AD pathogenesis. However, it remains undetermined if changes in the brain DHA content of phospholipids (PL) and DHA transporters exist in relation to APOE4, AD diagnosis and CAA pathology.MethodWe performed liquid chromatography/mass spectrometry‐based PL analysis of the cerebrovascular and parenchymal fractions from autopsied human brain of pathologically confirmed AD cases and controls. We performed an antibody‐based examination of the major facilitator superfamily domain containing 2A (mfsd2a) protein in the cerebrovasculature from these subjects and brain homogenates from transgenic mice with human APOE (APOE‐TR) and APOE‐TR crossed with mice with five AD mutations (EFAD). We performed proteomic analyses of the cerebrovascular and parenchymal fractions of the brains from 50‐week‐old APOE‐TR.ResultIn the cerebrovasculature and parenchyma, DHA containing PL species were lower in ε4 carriers with AD compared to control ε4 carriers. We observed an ε4‐dependent decrease in mfsd2a level in the cerebrovasculature of ε4 carriers compared to non‐carriers. Stratification of DHA containing PL by CAA showed that these PL levels were reduced in ε4 positive AD patients with severe CAA. In addition, brain levels of DHA containing PC species and mfsd2a were lower in APOE4‐TR and E4FAD mice compared to other genotypes in each mouse model. Furthermore, protein levels of glucose transporter 1 (Glut1) and a metabolite transporter, monocarboxylate transporter 1 (MCT1), were lower in the cerebrovasculature of APOE4‐TR relative to APOE3‐TR and APOE2‐TR mice.ConclusionThese findings demonstrate that brain DHA deficiencies in ε4 carriers may be due to reduced mfsd2a expression and partly associated with severe CAA. Thus, targeting this transport mechanism may improve the bioavailability of DHA into the brains of ε4 carriers who are at risk of developing AD.

Lipidome Atlas of the Developing Heart Uncovers Dynamic Membrane Lipid Attributes Underlying Cardiac Structural and Metabolic Maturation

Precise metabolic rewiring during heart organogenesis underlies normal cardiac development. Herein, we utilized high-coverage, quantitative lipidomic approaches to construct lipidomic atlases of whole hearts (861 lipids; 31 classes) and mitochondria (587 lipids; 27 classes) across prenatal and postnatal developmental stages in mice. We uncovered the progressive formation of docosahexaenoyl-phospholipids and enhanced remodeling of C18:2, C20:3, and C20:4 fatty acyl moieties into cardiolipins as cardiac development progresses. A preferential flow of ceramides toward sphingomyelin biosynthesis over complex glycosphingolipid formation was also noted. Using maSigPro and GPclust algorithms, we identified a repertoire of 448 developmentally dynamic lipids and mapped their expression patterns to a library of 550 biologically relevant developmentally dynamic genes. Our combinatorial transcriptomics and lipidomics approaches identified Hadha, Lclat1 , and Lpcat3 as candidate molecular drivers governing the dynamic remodeling of cardiolipins and phospholipids, respectively, in heart development. Our analyses revealed that postnatal cardiolipin remodeling in the heart constitutes a biphasic process, which first accumulates polyunsaturated C78-cardiolipins prior to tetralinoleoyl cardiolipin forming the predominant species. Multiomics analyses supplemented with transmission electron microscopy imaging uncovered enhanced mitochondria–lipid droplet contacts mediated by perilipin-5. Our combinatorial analyses of multiomics data uncovered an association between mitochondrial-resident, docosahexaenoic acid-phospholipids and messenger RNA levels of proton-transporting adenosine triphosphate synthases on inner mitochondrial membranes, which adds credence to the membrane pacemaker theory of metabolism. The current findings offer lipid-centric biological insights potentially important to understanding the molecular basis of cardiac metabolic flexibility and disease pathology.

Colt, multicenter capre open label randomized dose-ranging phase II trial to assess efficacy/safety in patients with mild-to-high hypertriglyceridemia

Objectives: Long-chain polyunsaturated omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are known to reduce hepatic secretion of triglyceride (TG)-rich lipoproteins and plasma TG levels. This study evaluated the efficacy of CaPre®, a novel highly purified omega-3 krill oil extract with a high EPA and DHA phospholipid conjugate content, to reduce fasting plasma TG ranging between 200-877 mg/dL after 4 and 8 weeks vs. Standard-Of-Care (SOC). Additional endpoints were changes in TC, LDL-C, HDL-C, non-HDL-C, HbA1c, Apo-AI, -AII, -CII, -CIII and –E.

COLT, Multicenter CaPre Open Label Randomized Dose-Ranging Phase II Trial to Assess Efficacy/Safety in Patients with Mild-to-High Hypertriglyceridemia

Background: Long-chain polyunsaturated omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been shown to reduce hepatic secretion of TG rich lipoproteins and plasma TG levels. CaPre® is a novel highly purified omega-3 krill oil extract with a high content of EPA and DHA phospholipid conjugates. Objective/Purpose: To evaluate the efficacy of CaPre® to reduce fasting plasma TG ranging between 200-877 mg/dL after 4 and 8 weeks vs. Standard Of Care (SOC). Additional endpoints were changes in TC, LDL-C, HDL-C, non-HDL-C, and HbA1c. Methods: Total of 288 patients from 34 centers aged 18-75 were randomized to Standard of Care (SOC), or CaPre® given daily with dose doubling at week 4 for 0.5g, 1g, and 2g groups while the 4g group was dosed for 8 weeks. Standard safety assessments were performed during the trial. Statistical analysis was performed using ANOVA followed by post-hoc contrast analysis assessing % change between baseline, week 4 and 8 with CaPre® compared to SOC. Results: CaPre® SOC-compared 4-week TG % difference was -8% (p=NS), -16% (p=0.007), -13% (p=0.025) and -18% (p=0.002), for 0.5g, 1g, 2g, and 4g, respectively, while the SOC-compared 8-week TG % difference was 2% (p=NS), 16% (p=0.021), -6% (p=NS) and -14% (p=0.038), for 0.5g, 1g, 2g, and 4g, respectively. CaPre® 4g SOC-compared 8-week TC % difference was -7% (p=0.06) and while the nonHDL-C was -10% (p=0.036). Similarly to beneficial lipid effects, HbA1c was significantly lowered with CaPre® 2g (-18%, p=0.013) and 4g (-15%, p=0.039). CaPre® was safe, well-tolerated, with incidence of AEs similar to SOC. Conclusions: CaPre® at daily doses of 1g-4g was effective and safe in reducing serum triglycerides and increasing HDL-C without deleterious effects on increasing LDL-C in patients with mild-to-high hypertriglyceridemia (NCT01516151).

Corrigendum: Improved Conformational Stability of the Visual G Protein‐Coupled Receptor Rhodopsin by Specific Interaction with Docosahexaenoic Acid Phospholipid

In this paper, the units for pressure were incorrectly given, and should have been mN m−1 as they refer to surface pressure. This affects Figures 1, 2 and 3, as well as two parts of the text on page 640 (in the penultimate paragraph on the left and first paragraph on the right). The corrected figures are given below. Kinetic adsorption process for the incorporation of rhodopsin to the air/water interface at different DDHA-PC initial pressures: 1 mN m−1 (curve 4), 6.1 mN m−1 (3), 10.4 mN m−1 (2) or absence of DDHA-PC (1). DDHA-PC stock solution was prepared and added drop wise to the subphase (PBS, pH 7.4) until the desired lipid pressure was achieved. The final concentration of rhodopsin was 1.4 nM. Determination of rhodopsin MIP. Plot of the surface pressure increase (Δπ) caused by rhodopsin against lipid initial surface pressure (πi) to determine the MIP of rhodopsin with DDHA-PC monolayers, by extrapolating the curve to the x-axis. The subphase was PBS (pH 7.4), and the final concentration of rhodopsin was 1.4 nM. Plot of the equilibrium adsorption pressure (πe) of rhodopsin against initial monolayer surface pressure (πi) of DDHA-PC. The subphase was PBS, pH 7.4, and the final concentration of rhodopsin was 1.4 nM. The editorial office apologises for this error.

Improved Conformational Stability of the Visual G Protein‐Coupled Receptor Rhodopsin by Specific Interaction with Docosahexaenoic Acid Phospholipid

Rhodopsin is the photoreceptor located in the rod cells of the retina. It has seven transmembrane helices and is a prototypic member of the G protein-coupled receptor superfamily. The structures and functions of these receptors are clearly affected by the lipid composition of the cell membrane, and their study in a purified recombinant form is usually performed in detergent solution. There is a need to study these receptors in a physiologically relevant environment because the lipid environment is known to have an important effect on their function. In this work, rhodopsin reconstituted in docosahexaenoic acid (DHA) liposomes is shown to have more thermal stability than when it is solubilised with the neutral detergent dodecyl maltoside. Moreover, the specific interaction between rhodopsin and DHA was followed by means of Langmuir experiments with insertion of rhodopsin into lipid monolayers; this showed high affinity for the lipid-receptor interaction. Furthermore, fluorescence spectroscopy measurements indicate that the conformation of opsin obtained after photobleaching is preserved in DHA-containing liposomes, thereby allowing retinal to re-enter the binding pocket even long after bleaching. Overall, our results demonstrate that liposomes of this specific lipid provide a more stable environment for ground-state inactive rhodopsin in the dark, than dodecyl maltoside detergent, and that this lipid can also preserve the native correctly folded ligand-free opsin conformation obtained after illumination. This strategy will be used in further studies on mutations of rhodopsin associated with congenital retinopathies.

Endogenous Signaling by Omega-3 Docosahexaenoic Acid-derived Mediators Sustains Homeostatic Synaptic and Circuitry Integrity

The harmony and function of the complex brain circuits and synapses are sustained mainly by excitatory and inhibitory neurotransmission, neurotrophins, gene regulation, and factors, many of which are incompletely understood. A common feature of brain circuit components, such as dendrites, synaptic membranes, and other membranes of the nervous system, is that they are richly endowed in docosahexaenoic acid (DHA), the main member of the omega-3 essential fatty acid family. DHA is avidly retained and concentrated in the nervous system and known to play a role in neuroprotection, memory, and vision. Only recently has it become apparent why the surprisingly rapid increases in free (unesterified) DHA pool size take place at the onset of seizures or brain injury. This phenomenon began to be clarified by the discovery of neuroprotectin D1 (NPD1), the first-uncovered bioactive docosanoid formed from free DHA through 15-lipoxygenase-1 (15-LOX-1). NPD1 synthesis includes, as agonists, oxidative stress and neurotrophins. The evolving concept is that DHA-derived docosanoids set in motion endogenous signaling to sustain homeostatic synaptic and circuit integrity. NPD1 is anti-inflammatory, displays inflammatory resolving activities, and induces cell survival, which is in contrast to the pro-inflammatory actions of the many of omega-6 fatty acid family members. We highlight here studies relevant to the ability of DHA to sustain neuronal function and protect synapses and circuits in the context of DHA signalolipidomics. DHA signalolipidomics comprises the integration of the cellular/tissue mechanism of DHA uptake, its distribution among cellular compartments, the organization and function of membrane domains containing DHA phospholipids, and the precise cellular and molecular events revealed by the uncovering of signaling pathways regulated by docosanoids endowed with prohomeostatic and cell survival bioactivity. Therefore, this approach offers emerging targets for prevention, pharmaceutical intervention, and clinical translation involving DHA-mediated signaling.

Neuroprotective effect of docosahexaenoic acid-enriched phospholipids in experimental diabetic neuropathy.

A deficiency in essential fatty acid metabolism has been widely reported in both human and animal diabetes. Fish oil supplementations (n-3 fatty acids), containing docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), were less effective on diabetic neuropathy than (n-6) fatty acids. This partial effect of (n-3) fatty acids might be attributed to the presence of EPA, a competitor of arachidonic acid, which enhanced the diabetes-induced decrease of this fatty acid in serum and tissues. For determining whether a supplementation with DHA alone could prevent neuropathy in streptozotocin-induced diabetes, diabetic rats were given daily, by gavage, liposomes containing DHA phospholipids, at a dose of 60 mg/kg. Eight weeks of diabetes induced significant decreases in nerve conduction velocity (NCV), nerve blood flow (NBF), and sciatic nerve and erythrocyte (red blood cells [RBCs]) Na,K-ATPase activities. DHA phospholipids totally prevented the decrease in NCV and NBF observed during diabetes when compared with the nonsupplemented diabetic group. DHA phospholipids also prevented the Na,K-ATPase activity decrease in RBC but not in sciatic nerve. Moreover, DHA level in sciatic nerve membranes was correlated with NCV. These results demonstrate a protective effect of daily doses of DHA on experimental diabetic neuropathy. Thus, treatment with DHA phospholipids could be suitable for evaluation in clinical trials.

Developmental maturation of hepatic n-3 polyunsaturated fatty acid metabolism: Supply of docosahexaenoic acid to retina and brain

Docasahexaenoic acid is an essential fatty acid enriched in lipids of photoreceptor, synaptic, and nerve growth cone membranes. [ 3H]docosahexaenoic acid was intraperitoneally injected in 5-day-old and 14-day-old mouse pups, and the labeling time course was followed in liver, plasma, brain, and retina for 72 hours. The liver of 5-day-old mice displayed higher content and labeling of triacylglycerols, lower content of phospholipids, and a more avid uptake of [ 3H]docosahexaenoic acid as compared with 14-day-old mice. Maximal [ 3H]docosahexaenoic acid labeling in the liver was observed 2 hr postinjection and decreased thereafter as [ 3H]docosahexaenoic acid accumulated in brain and retina. The most efficient [ 3H]docosahexaenoic acid accumulation in retina and brain occurred with 14-day-old pups and correlated with a higher labeling and a long half-life of [ 3H]docosahexaenoic acid phospholipids in liver (35 hr for 5-day-olds and 54 hr for 14-day-olds) and plasma (42 hr for 5 day-olds and 68 hr for 14-day-olds). As a function of time, the labeling profile in plasma lipids followed that of liver. A significant amount of total plasma decosahexaenoic acid was found esterified into cholesterol esters, while decosahexaenoic acid-phospholipids accounted for 60 to 70% at both ages. Docosahexaenoic acid cholesterol ester may also be a carrier of docosahexaenoic acid to neural tissues after synthesis in the liver and/or in high density lipoproteins from a liver-derived docosahexaenoic acid-phosphatidylcholine pool. Both cholesterol and docosahexaenoic acid are needed for neural membrane biogenesis. Collectively, these data indicate that the metabolism of docosahexaenoic acid by liver and the uptake and esterification of docosahexaenoic acid into hepatic lipids and its subsequent appearance in the plasma are developmentally regulated and under control by the liver. The esterification of docosahexaenoic acid into phospholipids and the increased half-life of [ 3H]docosahexaenoic acid-phospholipids in plasma may be salient factors modulating efficient docosahexaenoic acid delivery to the central nervous system.