Comparative Study of EPA-enriched Phosphatidylcholine and EPA-enriched Phosphatidylserine on Lipid Metabolism in Mice

Dietary Eicosapentaenoic Acid Containing Phosphoethanolamine Plasmalogens Remodels the Lipidome of White Adipose Tissue and Suppresses High-Fat Diet Induced Obesity in Mice

SCOPE

Dietary supplementation of docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) can alter the lipidome profiles of adipocytes, thereby counteract obesity. DHA/EPA in the form of phospholipids demonstrates higher bioavailability than triglyceride or ethyl ester (EE), but their effects on the lipidome and metabolic changes during obesity are still unknown.

METHODS AND RESULTS

High-fat diet-induced obese mice are treated with different molecular forms of EPA, and EPA supplemented as phosphoethanolamine plasmalogens (PlsEtn) has a superior effect on reducing fat mass accumulation than phosphatidylcholine (PC) or EE. The lipidomics analysis indicates that EPA in form of PlsEtn but not PC or EE significantly decreases total PC and sphingomyelin content in white adipose tissue (WAT). Some specific polyunsaturated fatty acid -containing PCs and ether phospholipids are increased in EPA-PlsEtn-fed mice, which may attribute to the upregulation of unsaturated fatty acid biosynthesis and fatty acid elongation reactions in WAT. In addition, the expression of genes related to fatty acid catabolism is also promoted by EPA-PlsEtn supplementation, which may cause the decreased content of saturated and monounsaturated fatty acid-containing PCs.

CONCLUSIONS

EPA-PlsEtn supplementation is demonstrated to remodel lipidome and regulate the fatty acid metabolic process in WAT, indicating it may serve as a new strategy for obesity treatment in the future.

A Comparative Study about the Neuroprotective Effects of DHA-Enriched Phosphatidylserine and EPA-Enriched Phosphatidylserine against Oxidative Damage in Primary Hippocampal Neurons

Nerve damage caused by accumulated oxidative stress is one of the characteristics and main mechanisms of Alzheimer's disease (AD). Previous studies have shown that phosphatidylserine (PS) rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) plays a significant role in preventing and mitigating the progression of AD. However, whether DHA-PS and EPA-PS can directly protect primary hippocampal neurons against oxidative damage has not been studied. Here, the neuroprotective functions of DHA-PS and EPA-PS against H₂O₂/t-BHP-induced oxidative damage and the possible mechanisms were evaluated in primary hippocampal neurons. It was found that DHA-PS and EPA-PS could significantly improve cell morphology and promote the restoration of neural network structure. Further studies showed that both of them significantly alleviated oxidative stress-mediated mitochondrial dysfunction. EPA-PS significantly inhibited the phosphorylation of ERK, thus playing an anti-apoptotic role, and EPA-PS significantly increased the protein expressions of p-TrkB and p-CREB, thus playing a neuroprotective role. In addition, EPA-PS, rather than DHA-PS could enhance synaptic plasticity by increasing the expression of SYN, and both could significantly reduce the expression levels of p-GSK3β and p-Tau. These results provide a scientific basis for the use of DHA/EPA-enriched phospholipids in the treatment of neurodegenerative diseases, and also provide a reference for the development of related functional foods.

Targeted Lipidomics Reveal the Effects of Different Phospholipids on the Phospholipid Profiles of Hepatic Mitochondria and Endoplasmic Reticulum in High-Fat/High-Fructose-Diet-Induced Nonalcoholic Fatty Liver Disease Mice

The lipid alternation in mitochondria and endoplasmic reticulum (ER) might be indicative of their abnormal morphology and function, which contribute to development of nonalcoholic fatty liver disease (NAFLD). However, the influence of dietary phospholipids (PLs) on the PL composition of the organellar membrane is largely unknown. High-fat/high-fructose (HFHF)-diet-induced NAFLD mice were administrated with different PLs (2%, w/w) with specific fatty acids and headgroups, including eicosapentaenoic acid (EPA)-phosphatidylcholine (PC)/phosphatidylethanolamine (PE)/phosphatidylserine (PS), docosahexaenoic acid (DHA)-PC/PE/PS, egg-PC/PE/PS, and soy-PC/PE/PS. After 8 weeks of feeding, PLs dramatically decreased hepatic lipid accumulation, in which EPA/DHA-PS had the best efficiency. Furthermore, lipidomic analysis revealed that the HFHF diet narrowed the difference in PL composition between mitochondria and ER, significantly reduced the PC/PE ratio, and changed the unsaturation of cardiolipin in mitochondria. Dietary PLs reversed these alterations. Heatmap analysis indicated that dietary PL groups containing the same fatty acids clustered together. Moreover, dietary PLs significantly increased the ratio of PC/PE in both hepatic mitochondria and ER, especially EPA-PE. This study showed that fatty acid composition of PLs might represent greater impact on the PL composition of the organellar membrane than headgroups.

Omega-3 phospholipids and obesity-associated NAFLD: Potential mechanisms and therapeutic perspectives

Prevalence of non-alcoholic fatty liver disease (NAFLD) increases in line with obesity and type 2 diabetes, and there is no approved drug therapy. Polyunsaturated fatty acids of n-3 series (omega-3) are known for their hypolipidaemic and anti-inflammatory effects. Existing clinical trials suggest varying effectiveness of triacylglycerol- or ethyl ester-bound omega-3 in the treatment of NAFLD, without affecting advanced stages such as non-alcoholic steatohepatitis. Preclinical studies suggest that the lipid class used to supplement omega-3 may determine the extent and nature of their effects on metabolism. Phospholipids of marine origin represent an alternative source of omega-3. The aim of this review is to summarise the available evidence on the use of omega-3 phospholipids, primarily in obesity-related NAFLD, and to outline perspectives of their use in the prevention/treatment of NAFLD. A PubMed literature search was conducted in May 2021. In total, 1088 articles were identified, but based on selection criteria, 38 original papers were included in the review. Selected articles describing the potential mechanisms of action of omega-3 phospholipids have also been included. Preclinical evidence clearly indicates that omega-3 phospholipids have strong antisteatotic effects in the liver, which are stronger compared to omega-3 administered as triacylglycerols. Multiple mechanisms are likely involved in the overall antisteatotic effects, involving not only the liver but also adipose tissue and the gut. Robust preclinical evidence for strong antisteatotic effects of omega-3 phospholipids in the liver should be confirmed in clinical trials. Further research is needed on the possible effects of omega-3 phospholipids on advanced NAFLD.

EPA-Enriched Phospholipids Alleviate Renal Interstitial Fibrosis in Spontaneously Hypertensive Rats by Regulating TGF-β Signaling Pathways

Hypertensive nephropathy is a chronic kidney disease caused by hypertension. Eicosapentaenoic acid (EPA) has been reported to possess an antihypertensive effect, and our previous study suggested that EPA-enriched phospholipid (EPA-PL) had more significant bioactivities compared with traditional EPA. However, the effect of dietary EPA-PL on hypertensive nephropathy has not been studied. The current study was designed to examine the protection of EPA-PL against kidney damage in spontaneously hypertensive rats (SHRs). Treatment with EPA-PL for three weeks significantly reduced blood pressure through regulating the renin–angiotensin system in SHRs. Moreover, dietary EPA-PL distinctly alleviated kidney dysfunction in SHRs, evidenced by reduced plasma creatinine, blood urea nitrogen, and 24 h proteinuria. Histology results revealed that treatment of SHRs with EPA-PL alleviated renal injury and reduced tubulointerstitial fibrosis. Further mechanistic studies indicated that dietary EPA-PL remarkably inhibited the activation of TGF-β and Smad 3, elevated the phosphorylation level of PI3K/AKT, suppressed the activation of NF-κB, reduced the expression of pro-inflammatory cytokines, including IL-1β and IL-6, and repressed the oxidative stress and the mitochondria-mediated apoptotic signaling pathway in the kidney. These results indicate that EPA-PL has potential value in the prevention and alleviation of hypertensive nephropathy.

Comparative Study of DHA with Different Molecular Forms for Ameliorating Osteoporosis by Promoting Chondrocyte-to-Osteoblast Transdifferentiation in the Growth Plate of Ovariectomized Mice

Osteoblasts play a key role in bone remodeling. Recent studies have reported that some hypertrophic chondrocytes co-expressing collagen I(Col I) and collagen X (ColX) could directly transdifferentiate into osteoblasts during endochondral ossification. However, whether nutrition intervention is beneficial to this transformation to improve osteoporosis (OP) remains unknown. In this study, ovariectomy (OVX)-induced OP mice were orally administered with docosahexaenoic acid (DHA) in different molecular forms for 13 weeks. The results showed that both DHA-triglyceride (DHA-TG) and DHA-phosphatidylcholine (DHA-PC) increased the bone mineral density and bone mineral apposition rate in ovariectomized mice, while DHA-ethyl esters (DHA-EE) had little effect. Interestingly, we found that both DHA-PC and DHA-TG increased the height of the growth plate, mainly increasing the number of hypertrophic chondrocytes. Further investigation by simultaneously labeling ColX and ColI indicated that DHA-PC and DHA-TG promoted the number of chondrocyte-transdifferentiated osteoblasts in the growth plate close to the diaphysis, in which DHA-PC performed better than DHA-TG. Apoptosis was not the only fate of hypertrophic chondrocytes. Western blot results showed that both DHA-TG and DHA-PC downregulated the Bax and cleaved-caspase3 expression and upregulated Bcl-2 expression in the growth plate, suggesting that chondrocyte apoptosis is inhibited. Runx2, the key regulator of chondrocyte-to-osteoblast transdifferentiation, was significantly increased by DHA-TG and DHA-PC, while DHA-EE had no effect on the above indicators. To our best knowledge, this is the first report that both DHA-PC and DHA-TG enhanced bone formation via promoting the chondrocyte-to-osteoblast transdifferentiation in the growth plate, contributing to the amelioration of OP. These activities depend on the molecular forms of DHA and their bioavailabilities. Our results provide guidance for the application of fish oil for bone health.

Dietary Sterols and Sterol Oxidation Products on Atherosclerosis: An Insight Provided by Liver Proteomic and Lipidomic

SCOPE

The development of atherosclerosis is closely associated with disorder of lipid metabolism. Dietary sterols and their oxidation products play a role in the pathogenesis of atherosclerosis. However, their effects on liver lipid metabolism during the atherosclerosis remain unknown.

METHODS AND RESULTS

Here, we apply lipidomic and proteomic analysis on liver of ApoE^-/- mice feed with phytosterols, cholesterol oxidation products (COPs), or phytosterol oxidation products (POPs) to profile lipid species and reveal the underlying mechanism. Dietary exposure of phytosterols, COPs, and POPs all reduce the accumulation of liver triglyceride (TG), but COPs and POPs accelerate the fibrosis of liver. Lipidomic analysis reveals that phytosterols mainly decrease the levels of phosphatidylinositol (PI), while COPs and POPs both increase the level of digalactosyldiacylglycerol (DGDG) and reduce TG with long-chain polyunsaturated fatty acids. Besides, COPs up-regulated levels of lipids associate with atherosclerosis risk, such as phosphatidylcholines (PC), phosphatidylethanolamine (PE) and ceramides (Cer). POPs down-regulate the level of acyl carnitine (AcCa). Furthermore, proteomic analysis shows that COPs promote oxidative phosphorylation and POPs inhibit the beta oxidation of fatty acids.

CONCLUSIONS

This study reveals that phytosterols, COPs, and POPs differently change the composition and metabolism of glycerophospholipids, sphingolipids, and glycerolipids in liver of ApoE^-/- mice.

A comparative study of the effects of phosphatidylserine rich in DHA and EPA on Aβ-induced Alzheimer's disease using cell models

Alzheimer's disease (AD) is an age-dependent, irreversible neurodegenerative disease, and one of the pathological features is amyloid-β (Aβ) deposition. Previous studies have shown that phosphatidylserine (PS) enriched with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) exhibited significant effects in preventing and alleviating the progress of AD. However, no studies have focused on the differences in the preventive effects on AD between EPA-PS and DHA-PS. Here, the effects of EPA-PS and DHA-PS on Aβ production, Aβ-induced neurotoxicity and Aβ clearance have been studied. The results show that DHA-PS significantly reduced Aβ production in CHO-APP/PS1 cells compared to EPA-PS. Moreover, both EPA-PS and DHA-PS significantly protected the primary hippocampal neurons against Aβ-induced toxicity by inhibiting the mitochondrial-dependent apoptotic pathway and phosphorylation of JNK and p38. Compared to DHA-PS, EPA-PS administration significantly improved the Aβ phagocytic capacity of BV2 cells. In addition, EPA-PS and DHA-PS significantly promoted the neurite outgrowth of primary hippocampal neurons. These findings might provide dietary guidance for the prevention of AD as well as a reference for the development of related functional foods.

Effect of big eye tuna (Thunnus obesus) head soup with different colloidal particle size on TG and TC deposition in FFA-exposed HepG2 cells

Micro/nanocolloidal is confirmed as a self-assembly structure in big eye tuna (Thunnus obesus) head soup, and lipids enriched with docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are the major component. In this study, the effect of big eye tuna head soup (BETHS) with different particle size micro/nanocolloidal on lipid accumulation was initially evaluated. The original soup and microfiltration soup (with or without ginger; OGS/OGSG and MFS/MFSG) were prepared firstly. A free fatty acid-exposed (FFA-exposed) HepG2 cell model was built using sodium oleic acid (OA) and sodium palmitic acid (PA) (2:1). The triglyceride (TG) and total cholesterol (TC) in the FFA-exposed HepG2 cells were 8.6 ng/104 cells and 0.6 nM/104 cells, respectively, which were significantly different with control (p < .05). Both OGS and OGSG could significantly decline the TG deposition of FFA-exposed HepG2 cells with 31% and 40% (p < .05), and in MFS and MFSG were 23% and 26% (p ≥ .05). Meanwhile, OGS inhibited the deposition of TG mainly in 18-24 hr, and OGSG mainly in 12-18 hr. All the BETHS samples showed no inhibition effect on TC deposition (p ≥ .05). This research might help to understand the improving activity of natural or traditional food products on metabolic syndrome.

Advances in the Study of Marine Products with Lipid-Lowering Properties

With twice the number of cancer's deaths, cardiovascular diseases have become the leading cause of death worldwide. Atherosclerosis, in particular, is a progressive, chronic inflammatory cardiovascular disease caused by persistent damage to blood vessels due to elevated cholesterol levels and hyperlipidemia. This condition is characterized by an increase in serum cholesterol, triglycerides, and low-density lipoprotein, and a decrease in high-density lipoprotein. Although existing therapies with hypolipidemic effects can improve the living standards of patients with cardiovascular diseases, the drugs currently used in clinical practice have certain side effects, which insists on the need for the development of new types of drugs with lipid-lowering effects. Some marine-derived substances have proven hypolipidemic activities with fewer side effects and stand as a good alternative for drug development. Recently, there have been thousands of studies on substances with lipid-lowering properties of marine origin, and some are already implemented in clinical practice. Here, we summarize the active components of marine-derived products having a hypolipidemic effect. These active constituents according to their source are divided into algal, animal, plant and microbial and contribute to the development and utilization of marine medicinal products with hypolipidemic effects.

Effect of fish paste products "Hanpen" intake in Sprague-Dawley rats

Fish paste product, "Hanpen," is a traditional type of Japanese food made from minced fish as well as imitation crab and kamaboko, and a marshmallow-like soft texture is characteristic of hanpen. Hanpen is known as a high-protein and low-fat food. However, there is a lack of evidence on its health benefits. The aim of this study was to investigate the effects of hanpen intake on organ weight and biomarker levels in Sprague-Dawley rats with diets consisting of hanpen for 84 days as an initial study. Male, 6-week-old Sprague-Dawley rats were divided into two groups: group I, fed normal diets, and group II, fed normal diets with 5% dried hanpen. Throughout the 84-day treatment period, we checked body weight and food intake, and after 84 days, we performed organ weight and blood biochemical analyses. No significant differences were seen in body weight, food intake, organ weight, and most biochemical parameters between group I and group II. Interestingly, total cholesterol (T-CHO) and high-density lipoprotein cholesterol (HDL-C) levels of group II were significantly higher than those of group I after administration for 84 days. Moreover, lactate dehydrogenase (LDH) level of group II was marked lower than that of group I, and other liver function parameters of group II tended to be lower than those of group I. As conclusion, "Hanpen," a Japanese traditional food, could be effective as a functional food for human health management worldwide.

A pilot study on the effects of DHA/EPA-enriched phospholipids on aerobic and anaerobic exercises in mice

DHA/EPA-PL andl-carnitine had significant effects on aerobic exercise, while astaxanthin improved anaerobic exercise. The possible mechanism involved carbohydrate and lipid metabolism, mitochondrial respiratory chain and tricarboxylic acid cycle.

Comparative studies of DHA-enriched phosphatidylcholine and recombination of DHA-ethyl ester with egg phosphatidylcholine on ameliorating memory and cognitive deficiency in SAMP8 mice

DHA-PLs (DHA-PC) could not be substituted by recombination of commercial fish oil with DHA-free PC in alleviating age-related memory loss and cognitive deficiency in SAMP8 mice.

Synergistic effect of eicosapentaenoic acid-enriched phospholipids and sea cucumber saponin on orotic acid-induced non-alcoholic fatty liver disease in rats

Non-alcoholic fatty liver disease (NAFLD) is becoming an increasingly prevalent chronic liver disease all over the world. The present study was undertaken to explore the synergistic effects of sea cucumber saponins (SCS) and eicosapentaenoic acid-enriched phospholipids (EPA-PL) at ratios of 0.5 : 0.5 and 1 : 1 on NAFLD and demonstrate possible protective mechanisms. It was found that the combination of EPA-PL and SCS at half dose exhibited better effects than EPA-PL or SCS alone and the combination of EPA-PL and SCS at full dose in alleviating orotic acid (OA)-induced symptoms including growth parameters, serum parameters and liver function. Further evaluation of the mechanism illustrated that EPA-PL and SCS combination at the ratio of 0.5 : 0.5 could markedly reduce the mRNA expressions of fatty acid synthase, acetyl-CoA carboxylase, glucose-6-phosphate dehydrogenase and malic enzyme genes and significantly increase expression of genes relevant to fatty acid β-oxidation including peroxisome proliferator-activated receptor and its target genes (CPT1, CPT2 and ACOX1), suggesting that the protection of the EPA-PL and SCS combination at the ratio of 0.5 : 0.5 against OA-induced NAFLD might be mainly via lipogenesis inhibition and β-oxidation enhancement in the liver. The synergistic effects of EPA-PL and SCS make it possible to reduce the doses of EPA-PL or SCS to avoid side effects, which is of value for the development of dietary supplements or functional foods for preventing or treating NAFLD.

Mechanisms of DHA-enriched phospholipids in improving cognitive deficits in aged SAMP8 mice with high-fat diet

Recent studies have shown that a high-fat diet (HFD) is involved in both metabolic dysfunction and cognitive deficiency and that docosahexaenoic-acid-enriched phospholipids (DHA-PLs) have beneficial effects on obesity and cognitive impairment. However, there are only a few studies comparing differences between DHA-PC and DHA-PS in HFD-induced Alzheimer's disease (AD) models. After 8 weeks feeding with HFD, 10-month-old SAMP8 mice were fed with 1% (w/w) DHA-PC or 1% DHA-PS (biosynthesized from DHA-PC) for 8 weeks; we then tested the behavioral performances in the Barnes maze test and Morris maze test. The changes of the generation and accumulation of Aβ, oxidative stress, apoptosis, neuroinflammation and neurotrophic factors were also measured. The results indicated that both DHA-PC and DHA-PS significantly improved the metabolic disorders and cognitive deficits. Both DHA-PC and DHA-PS could ameliorate oxidative stress, and DHA-PS presented more notable benefits than DHA-PC on Aβ pathology, mitochondrial damage, neuroinflammation and neurotrophic factors; DHA-PS was for the first time found to increase the production of insoluble Aβ (less pathogenic) in this AD model. These data suggest that DHA-PLs can significantly improve cognitive deficiency, and the molecular mechanisms for this closely relate to the phospholipid polar groups.