UPLC-MS based lipidomics analysis on optimization of soybean phosphatidylethanolamine extraction

Soybean-derived phosphatidylethanolamine (PE) is a valuable phospholipid component yet its high-purity form is costly and its molecular structure is poorly understood. The present study combined solvent extraction and cryopurification to purify PE. The optimal extraction conditions were as follows: material-liquid ratio 1:15 (g/mL), ethanol base concentration 100:4 (Vanhydrous ethanol /V25% ammonia), extraction temperature 40 °C, time 60 min, extraction twice. The cryopurification conditions were: material-liquid ratio 1:60, ethanol base concentration 100:6 (Vanhydrous ethanol/V25% ammonia), freezing temperature - 20 °C, time 20 h. UPLC-QTOF-MS/MS analysis revealed phospholipid composition of raw material, crude product, and purified product. The results showed that the purity of PE in the purified products was 76.74%, and the yield was 72.43% under optimal conditions. 181 phospholipid molecules were quantified. The study successfully explored high-purity PE preparation method and the composition of PE product. It provides a basis for the subsequent exploration of its biofunction and potential applications.

Promising Strategies to Reduce the SARS-CoV-2 Amyloid Deposition in the Brain and Prevent COVID-19-Exacerbated Dementia and Alzheimer's Disease

The COVID-19 pandemic, caused by infection with the SARS-CoV-2 virus, is associated with cognitive impairment and Alzheimer's disease (AD) progression. Once it enters the brain, the SARS-CoV-2 virus stimulates accumulation of amyloids in the brain that are highly toxic to neural cells. These amyloids may trigger neurological symptoms in COVID-19. The meningeal lymphatic vessels (MLVs) play an important role in removal of toxins and mediate viral drainage from the brain. MLVs are considered a promising target to prevent COVID-19-exacerbated dementia. However, there are limited methods for augmentation of MLV function. This review highlights new discoveries in the field of COVID-19-mediated amyloid accumulation in the brain associated with the neurological symptoms and the development of promising strategies to stimulate clearance of amyloids from the brain through lymphatic and other pathways. These strategies are based on innovative methods of treating brain dysfunction induced by COVID-19 infection, including the use of photobiomodulation, plasmalogens, and medicinal herbs, which offer hope for addressing the challenges posed by the SARS-CoV-2 virus.

Lipidomic Comparisons of Whole Cream Buttermilk Whey and Cheese Whey Cream Buttermilk of Caprine Milk

Buttermilk is a potential material for the production of a milk fat globule membrane (MFGM) and can be mainly classified into two types: whole cream buttermilk and cheese whey cream buttermilk (WCB). Due to the high casein micelle content of whole cream buttermilk, the removal of casein micelles to improve the purity of MFGM materials is always required. This study investigated the effects of rennet and acid coagulation on the lipid profile of buttermilk rennet-coagulated whey (BRW) and buttermilk acid-coagulated whey (BAW) and compared them with WCB. BRW has significantly higher phospholipids (PLs) and ganglioside contents than BAW and WCB. The abundance of arachidonic acid (ARA)- and eicosapentaenoic acid (EPA)-structured PLs was higher in WCB, while docosahexaenoic acid (DHA)-structured PLs were higher in BRW, indicating that BRW and WCB intake might have a greater effect on improving cardiovascular conditions and neurodevelopment. WCB and BRW had a higher abundance of plasmanyl PL and plasmalogen PL, respectively. Phosphatidylcholine (PC) (28:1), LPE (20:5), and PC (26:0) are characteristic lipids among BRW, BAW, and WCB, and they can be used to distinguish MFGM-enriched whey from different sources.

Lipid metabolism and oxidative stress in patients with Alzheimer's disease and amnestic mild cognitive impairment

Lipid metabolism and oxidative stress are key mechanisms in Alzheimer's disease (AD). The link between plasma lipid metabolites and oxidative stress in AD patients is poorly understood. This study was to identify markers that distinguish AD and amnestic mild cognitive impairment (aMCI) from NC, and to reveal potential links between lipid metabolites and oxidative stress. We performed non-targeted lipid metabolism analysis of plasma from patients with AD, aMCI, and NC using LC-MS/MS. The plasma malondialdehyde (MDA), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) levels were assessed. We found significant differences in lipid metabolism between patients with AD and aMCI compared to those in NC. AD severity is associated with lipid metabolites, especially TG (18:0_16:0_18:0) + NH4, TG (18:0_16:0_16:0) + NH4, LPC(16:1e)-CH3, and PE (20:0_20:4)-H. SPH (d16:0) + H, SPH (d18:1) + H, and SPH (d18:0) + H were high-performance markers to distinguish AD and aMCI from NC. The AUC of three SPHs combined to predict AD was 0.990, with specificity and sensitivity as 0.949 and 1, respectively; the AUC of three SPHs combined to predict aMCI was 0.934, with specificity and sensitivity as 0.900, 0.981, respectively. Plasma MDA concentrations were higher in the AD group than in the NC group (p = 0.003), whereas plasma SOD levels were lower in the AD (p < 0.001) and aMCI (p = 0.045) groups than in NC, and GSH-Px activity were higher in the AD group than in the aMCI group (p = 0.007). In addition, lipid metabolites and oxidative stress are widely associated. In conclusion, this study distinguished serum lipid metabolism in AD, aMCI, and NC subjects, highlighting that the three SPHs can distinguish AD and aMCI from NC. Additionally, AD patients showed elevated oxidative stress, and there are complex interactions between lipid metabolites and oxidative stress.

Neuroprotective Profile of Triazole Grandisin Analogue against Amyloid-Beta Oligomer-Induced Cognitive Impairment

Alzheimer's disease (AD) is a neurodegenerative disorder caused by accumulation of amyloid-β oligomers (AβO) in the brain, neuroinflammation, oxidative stress, and cognitive decline. Grandisin, a tetrahydrofuran neolignan, exhibits relevant anti-inflammatory and antioxidant properties. Interestingly, grandisin-based compounds were shown to prevent AβO-induced neuronal death in vitro. However, no study has assessed the effect of these compounds on the AD animal model. This study focuses on a triazole grandisin analogue (TGA) synthesized using simplification and bioisosteric drug design, which resulted in improved potency and solubility compared with the parent compound. This study aimed to investigate the possible in vivo effects of TGA against AβO-induced AD. Male C57/Bl6 mice underwent stereotaxic intracerebroventricular AβO (90 μM) or vehicle injections. 24 h after surgery, animals received intraperitoneal treatment with TGA (1 mg/kg) or vehicle, administered on a 14 day schedule. One day after treatment completion, a novel object recognition task (NORT) was performed. Memantine (10 mg/kg) was administered as a positive control. NORT retention sessions were performed on days 8 and 16 after AβO injection. Immediately after retention sessions, animals were euthanized for cortex and hippocampus collection. Specimens were subjected to oxidative stress and cytokine analyses. TGA reduced the level of cortex/hippocampus lipoperoxidation and prevented cognitive impairment in AβO-injected mice. Additionally, TGA reduced tumor necrosis factor (TNF) and interferon-γ (IFN-γ) levels in the hippocampus. By contrast, memantine failed to prevent cortex/hippocampus lipid peroxidation, recognition memory decline, and AβO-induced increases in TNF and IFN-γ levels in the hippocampus. Thus, memantine was unable to avoid the AβO-induced persistent cognitive impairment. The results showed that TGA may prevent memory impairment by exerting antioxidant and anti-inflammatory effects in AβO-injected mice. Moreover, TGA exhibited a persistent neuroprotective effect compared to memantine, reflecting an innovative profile of this promising agent against neurodegenerative diseases, such as AD.

Quantitative benefit and risk assessment of arsenic and nutrient levels in tilapia products sold on Chinese e-commerce platforms

E-commerce platforms have become a significant sales channel for processed tilapia products such as frozen tilapia fillets, pickled tilapia, and canned tilapia in China. As food safety issues are worldwide concerned, the imbalance between the nutritional benefits of fish and the risk of contamination has become a major constraint on fish consumption. Therefore, it is necessary to assess the safety of tilapia products sold on e-commerce platforms. We conducted a quantitative benefit-risk assessment of arsenic and nutrient levels for tilapia products sold on Chinese e-commerce platforms using the hazard quotient (HQ). A total of 147 tilapia products were collected from the central Chinese e-commerce platforms Tmall, Taobao, and Jingdong for arsenic determination. Arsenic concentrations in tilapia products ranged from 0.004 to 0.820 mg·kg-1. The inorganic arsenic content of tilapia products was lower than the national limit (0.1 mg·kg-1). One-way analysis of variance revealed that there was no significant difference in arsenic levels in tilapia products among different regions (p > 0.05), while there was a significant difference in product form, with canned tilapia containing significantly higher arsenic levels than frozen tilapia fillets and pickled tilapia fillets (p < 0.05). We conducted an aquaculture experiment to analyze the nutrient levels of tilapia. The mean value of EPA + DHA content of tilapia was 20.634 mg·100 g-1. The HQ values of tilapia products ranged from 0.004 to 0.736. In a word, the nutritional benefits of consuming tilapia products exceed the risk of arsenic exposure. These data can help demonstrate that tilapia products are low-risk, high-yield nutritious food and provide relevant safety recommendations for consumers purchasing processed tilapia products online.

Marine Plasmalogens: A Gift from the Sea with Benefits for Age-Associated Diseases

Aging increases oxidative and inflammatory stress caused by a reduction in metabolism and clearance, thus leading to the development of age-associated diseases. The quality of our daily diet and exercise is important for the prevention of these diseases. Marine resources contain various valuable nutrients, and unique glycerophospholipid plasmalogens are found abundantly in some marine invertebrates, including ascidians. One of the major classes, the ethanolamine class (PlsEtn), exists in a high ratio to phospholipids in the brain and blood, while decreased levels have been reported in patients with age-associated diseases, including Alzheimer's disease. Animal studies have shown that the administration of marine PlsEtn prepared from marine invertebrates improved PlsEtn levels in the body and alleviated inflammation. Animal and human studies have reported that marine PlsEtn ameliorates cognitive impairment. In this review, we highlight the biological significance, relationships with age-associated diseases, food functions, and healthcare materials of plasmalogens based on recent knowledge and discuss the contribution of marine plasmalogens to health maintenance in aging.

Phosphatidylethanolamine homeostasis under conditions of impaired CDP-ethanolamine pathway or phosphatidylserine decarboxylation

Phosphatidylethanolamine is the major inner-membrane lipid in the plasma and mitochondrial membranes. It is synthesized in the endoplasmic reticulum from ethanolamine and diacylglycerol (DAG) by the CDP-ethanolamine pathway and from phosphatidylserine by decarboxylation in the mitochondria. Recently, multiple genetic disorders that impact these pathways have been identified, including hereditary spastic paraplegia 81 and 82, Liberfarb syndrome, and a new type of childhood-onset neurodegeneration-CONATOC. Individuals with these diseases suffer from multisystem disorders mainly affecting neuronal function. This indicates the importance of maintaining proper phospholipid homeostasis when major biosynthetic pathways are impaired. This study summarizes the current knowledge of phosphatidylethanolamine metabolism in order to identify areas of future research that might lead to the development of treatment options.

Plasmalogen in the brain: Effects on cognitive functions and behaviors attributable to its properties

Ether phospholipid compositions are altered in the plasma or brain of patients with brain disorders, such as Alzheimer and Parkinson's disease, including those with psychiatric disorders like schizophrenia and bipolar disorders. Notably, plasmenyl ethanolamine has a unique chemical structure, i.e., a vinyl-ether bond at the sn-1 position, which mainly links with polyunsaturated fatty acids (PUFAs) at the sn-2 position. Those characteristic moieties give plasmalogen molecules unique biophysical and chemical properties that modulate membrane trafficking, lipid rafts, intramolecular PUFA moieties, and oxidative states. Previous reports suggested that a deficiency in plasmenyl ethanolamine leads to disturbances of the myelin structure, synaptic neurotransmission and intracellular signaling, apoptosis of neurons, and neuroinflammation, accompanied by cognitive disturbances and aberrant behaviors like hyperactivity in mice. Therefore, this review summarizes the relationship between the biological functions of plasmalogen. We also proposed biophysical properties that alter brain phospholipid compositions related to aberrant behaviors and cognitive dysfunction. Finally, a brief review of possible remedial plasmalogen replacement therapies for neurological, psychiatric, and developmental disorders attributable to disturbed plasmalogen compositions in the organs and cells was conducted.

Regulation of plasmalogen metabolism and traffic in mammals: The fog begins to lift

Due to their unique chemical structure, plasmalogens do not only exhibit distinct biophysical and biochemical features, but require specialized pathways of biosynthesis and metabolization. Recently, major advances have been made in our understanding of these processes, for example by the attribution of the gene encoding the enzyme, which catalyzes the final desaturation step in plasmalogen biosynthesis, or by the identification of cytochrome C as plasmalogenase, which allows for the degradation of plasmalogens. Also, models have been presented that plausibly explain the maintenance of adequate cellular levels of plasmalogens. However, despite the progress, many aspects around the questions of how plasmalogen metabolism is regulated and how plasmalogens are distributed among organs and tissues in more complex organisms like mammals, remain unresolved. Here, we summarize and interpret current evidence on the regulation of the enzymes involved in plasmalogen biosynthesis and degradation as well as the turnover of plasmalogens. Finally, we focus on plasmalogen traffic across the mammalian body - a topic of major importance, when considering plasmalogen replacement therapies in human disorders, where deficiencies in these lipids have been reported. These involve not only inborn errors in plasmalogen metabolism, but also more common diseases including Alzheimer's disease and neurodevelopmental disorders.

Polyrhachis vicina Roger Alleviates Memory Impairment in a Rat Model of Alzheimer's Disease Through the EGR1/BACE1/APP Axis

Memory deficits and loss are the earliest and most prominent features of Alzheimer's disease (AD). This study was aimed to clarify the mechanistic basis of an active fraction of Polyrhachis vicina Roger (AFPR) on the memory abilities of AD rat models, which involves early growth response 1 (EGR1) expression and β-secretase 1 (BACE1)-mediated deposition of amyloid β peptide (Aβ). An AD rat model was developed by Aβ25-35, which was further treated with AFPR alone or in combination with lentiviral EGR1. The Morris water maze test and HE and Fluoro-Jade C staining were adopted to observe the memory behaviors, hippocampus neuron morphology, and Aβ deposition. Aβ25-35-induced SK-N-SH and HT22 neurons were subjected to AFPR for in vitro experiments on neuronal viability and apoptosis. AFPR improved the impaired memory function, preserved the neuron structure, and suppressed Aβ deposition in AD rat models. Further, the expression of APP pathway-related proteins was downregulated by AFPR in both rat and cellular models. Moreover, AFPR inhibited the Aβ25-35-induced neuronal apoptosis. AFPR suppressed the expression of EGR1, downregulated the BACE1 expression via impeding the binding of EGR1 to the BACE1 promoter, and thus blocked the activation of the APP signaling, ultimately protecting neurons. Notably, the aforementioned effects of AFPR were in a concentration-dependent manner; among three doses, 3.65, 15.6, and 30 mg/(kg·d), high-dose AFPR exhibited the most appreciable effects. In conclusion, AFPR inhibited the BACE1 expression by repressing the binding of EGR1 to the promoter of BACE1, thereby suppressing the Aβ deposition and improving the memory function of AD rats.

In-depth investigation of the mechanisms of Echinacea purpurea polysaccharide mitigating alcoholic liver injury in mice via gut microbiota informatics and liver metabolomics

Accumulating evidence suggests that the pathogenesis of alcoholic liver disease (ALD) is strongly correlated with abnormalities of the gut-liver axis. Echinacea purpurea polysaccharide (EPP) is a homogeneous polysaccharide, which has been shown to mitigate ALD. However, the effects of EPP on gut microbiome and consequently on hepatic metabolism have yet to be explored. In this study, the microbiome and metabolomics were combined to explore the effects of EPP on gut microbiota and hepatic metabolism, and the relationship between both was further revealed by Spearman correlation analysis. Results exhibited EPP reversed alcohol-induced disturbances in gut microbiota, evidenced by increased abundance of Muribaculaceae, Lactobacillus, and Bacteroides and decreased abundance of Escherichia_Shigella and Enterococcus. Besides, EPP promoted the production of n-butyric acid, a short-chain fatty acid that maintains the integrity of the intestinal barrier. Moreover, EPP improved alterations in hepatic metabolites, and characteristic metabolites such as Berberine and Ponasterone as well as key metabolic pathways, particularly Nitrogen metabolism, were identified. Furthermore, correlation analysis suggested significant associations between gut microbes and hepatic metabolites, which in turn confirmed EPP alleviated ALD via the gut-liver axis. Therefore, these findings elucidated in-depth mechanisms of EPP against ALD and provided a new target for intervention in alcohol-related diseases.

Clinical and Pathological Benefits of Scallop-Derived Plasmalogen in a Novel Mouse Model of Alzheimer’s Disease with Chronic Cerebral Hypoperfusion

Background: The oral ingestion of scallop-derived plasmalogen (sPlas) significantly improved cognitive function in Alzheimer’s disease (AD) patients. Objective: However, the effects and mechanisms of sPlas on AD with chronic cerebral hypoperfusion (CCH), a class of mixed dementia contributing to 20–30% among the dementia society, were still elusive. Methods: In the present study, we applied a novel mouse model of AD with CCH to investigate the potential effects of sPlas on AD with CCH. Results: The present study demonstrated that sPlas significantly recovered cerebral blood flow, improved motor and cognitive deficits, reduced amyloid-β pathology, regulated neuroinflammation, ameliorated neural oxidative stress, and inhibited neuronal loss in AD with CCH mice at 12 M. Conclusion: These findings suggest that sPlas possesses clinical and pathological benefits for AD with CCH in the novel model mice. Furthermore, sPlas could have promising prevention and therapeutic effects on patients of AD with CCH.

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.

Plasmalogens improve swimming performance by modulating the expression of genes involved in amino acid and lipid metabolism, oxidative stress, and ferroptosis in an Alzheimer's disease zebrafish model

Plasmalogens (PLs) are critical to human health. Studies have reported a link between the downregulation of PLs levels and cognitive impairments in patients with Alzheimer's disease (AD). However, the underlying mechanisms remain to be clarified. In the present study, an AlCl₃-induced AD zebrafish model was established, and the model was used to elucidate the neuroprotective effects of PLs on AD by analysing the transcriptional profiles of zebrafish in the control, AD model, AD_PL, and PL groups. Chronic AlCl₃ exposure caused swimming performance impairments in the zebrafish, yet PLs supplementation could improve the dyskinesia recovery rate in the AD zebrafish model. Through transcriptional profiling, a total of 5413 statistically significant differentially expressed genes (DEGs) were identified among the groups. In addition to the DEGs involved in amino acid metabolism, we found that the genes related to iron homeostasis, lipid peroxidation, and oxidative stress, all of which contribute to ferroptosis, were dramatically altered among different groups. These results suggest that seafood-derived PLs, in addition to their role in eliminating oxidative stress, can improve the swimming performance in AlCl₃-exposed zebrafish partly by suppressing neuronal ferroptosis and accelerating synaptic transmission at the transcriptional level. This study provides evidence for PLs to be developed as a functional food supplement to relieve AD symptoms.

Dietary Ethanolamine Plasmalogen Alleviates DSS-Induced Colitis by Enhancing Colon Mucosa Integrity, Antioxidative Stress, and Anti-inflammatory Responses via Increased Ethanolamine Plasmalogen Molecular Species: Protective Role of Vinyl Ether Linkages

Dietary ethanolamine plasmalogen (PlsEtn) has been reported to have several health benefits; however, its functional role during colon pathophysiology remains elusive. The present study investigated the anticolitis effect of dietary ethanolamine glycerophospholipids (EtnGpls) with high PlsEtn from ascidian muscle (86.2 mol %) and low PlsEtn from porcine liver (7.7 mol %) in dextran sulfate sodium (DSS)-induced colitis in mice. Dietary EtnGpls lowered myeloperoxidase activity, thiobarbituric acid-reactive substances, proinflammatory cytokines and proapoptosis-related protein levels in colon mucosa after 16 days of DSS treatment, with ascidian muscle (0.1% EtnGpl in diet) showing higher suppression than porcine liver (0.1% EtnGpl in diet). Moreover, dietary EtnGpls suppressed DSS symptoms after 38 days of DSS treatment as evidenced by increased body weight, colon length, and ameliorated colon mucosa integrity. Additionally, dietary EtnGpls elevated short-chain fatty acid production in DSS-treated mice. Altogether, these results indicate the potential of utilizing diets with abundant PlsEtn for the prevention of colon inflammation-related disorders.

Plasmalogen Replacement Therapy

Plasmalogens, a subclass of glycerophospholipids containing a vinyl-ether bond, are one of the major components of biological membranes. Changes in plasmalogen content and molecular species have been reported in a variety of pathological conditions ranging from inherited to metabolic and degenerative diseases. Most of these diseases have no treatment, and attempts to develop a therapy have been focusing primarily on protein/nucleic acid molecular targets. However, recent studies have shifted attention to lipids as the basis of a therapeutic strategy. In these pathological conditions, the use of plasmalogen replacement therapy (PRT) has been shown to be a successful way to restore plasmalogen levels as well as to ameliorate the disease phenotype in different clinical settings. Here, the current state of PRT will be reviewed as well as a discussion of future perspectives in PRT. It is proposed that the use of PRT provides a modern and innovative molecular medicine approach aiming at improving health outcomes in different conditions with clinically unmet needs.

Short-term supplementation of DHA-enriched phospholipids attenuates the nephrotoxicity of cisplatin without compromising its antitumor activity in mice

Cisplatin is one of the most effective chemotherapeutic agents used for the treatment of a wide variety of cancers. However, cisplatin has been associated with nephrotoxicity, which limits its application in clinical treatment. Various studies have indicated the protective effect of phospholipids against acute kidney injury. However, no study has focused on the different effects of phospholipids with different fatty acids on cisplatin-induced nephrotoxicity and on the combined effects of phospholipids and cisplatin in tumour-bearing mice. In the present study, the potential renoprotective effects of phospholipids with different fatty acids against cisplatin-induced nephrotoxicity were investigated by determining the serum biochemical index, renal histopathological changes, protein expression level and oxidative stress. The results showed that docosahexaenoic acid-enriched phospholipids (DHA-PL) and eicosapentaenoic acid-enriched phospholipids (EPA-PL) could alleviate cisplatin-induced nephrotoxicity by regulating the caspase signaling pathway, the SIRT1/PGC1α pathway, and the MAPK (mitogen-activated protein kinase) signaling pathway and by inhibiting oxidative stress. In particular, DHA-PL exhibited a better inhibitory effect on oxidative stress and apoptosis compared to EPA-PL. Furthermore, DHA-PL exhibited an additional effect with cisplatin on the survival of ascitic tumor-bearing mice. These findings suggested that DHA-PL are one kind of promising supplement for the alleviation of cisplatin-induced nephrotoxicity without compromising its antitumor activity.

Serum Phosphatidylethanolamine and Lysophosphatidylethanolamine Levels Differentiate Alzheimer's Disease from Controls and Predict Progression from Mild Cognitive Impairment

BACKGROUND

There is intense interest in the development of blood-based biomarkers, not only that can differentiate Alzheimer's disease (AD) from controls, but that can also predict conversion from mild cognitive impairment (MCI) to AD. Serum biomarkers carry the potential advantage over imaging or spinal fluid markers both in terms of cost and invasiveness.

OBJECTIVE

Our objective was to measure the potential for serum lipid markers to differentiate AD from age-matched healthy controls as well as to predict conversion from MCI to AD.

METHODS

Using a publicly-available dataset, we examined the relationship between baseline serum levels of 349 known lipids from 16 classes of lipids to differentiate disease state as well as to predict the conversion from MCI to AD.

RESULTS

We observed that several classes of lipids (cholesteroyl ester, phosphatidylethanolamine, lysophosphatidylethanolamine, and acylcarnitine) differentiated AD from normal controls. Among these, only two classes, phosphatidylethanolamine (PE) and lysophosphatidylethanolamine (lyso-PE), predicted time to conversion from MCI to AD. Low levels of PE and high levels of lyso-PE result in two-fold faster median time to progression from MCI to AD, with hazard ratios 0.62 and 1.34, respectively.

CONCLUSION

These data suggest that serum PE and lyso-PE may be useful biomarkers for predicting MCI to AD conversion. In addition, since PE is converted to lyso-PE by phospholipase A2, an important inflammatory mediator that is dysregulated in AD, these data suggest that the disrupted serum lipid profile here may be related to an abnormal inflammatory response early in the AD pathologic cascade.

Structural changes of ethanolamine plasmalogen during intestinal absorption

Considerable attention has been paid to the absorption mechanisms of plasmalogen (Pls) because its intake has been expected to have preventive effects on brain-related diseases. Possible structural changes of Pls during absorption (i.e., preferential arachidonic acid re-esterification at the sn-2 position and base conversion of ethanolamine Pls (PE-Pls) into choline Pls (PC-Pls)) have previously been proposed. Since the physiological functions of Pls differ according to its structure, further elucidation of such structural changes during absorption is important to understand how Pls exerts its physiological effects in vivo. Hence, the absorption mechanism of Pls was investigated using the lymph-cannulation method and the everted jejunal sac model, with a focus on Pls molecular species. In the lymph-cannulation method, relatively high amounts of PE-Pls 18:0/20:4 and PC-Pls 18:0/20:4 were detected from the lymph even though these species were minor in the administered emulsion. Moreover, a significant increase of PE-Pls 18:0/20:4 and PC-Pls 18:0/20:4 in the intestinal mucosa was also confirmed by the everted jejunal sac model. Therefore, structural changes of PE-Pls in the intestinal mucosa were strongly suggested. The results of this study may provide an understanding of the relationship between intestinal absorption of Pls and exertion of its physiological functions in vivo.

Phospholipidomics quality evaluation of swimming crabs (Portunus trituberculatus) cultured with formulated feed, frozen trash fish, and mixed feed, a non-target approach by HILIC-MS

Swimming crab, Portunus trituberculatus, is popularly consumed because of its flavor and nutritional value. Herein, the crabs cultivated with formulated feed, frozen trash fish, and mixed feed were lipidomically analyzed by non-target HILIC-QTRAP/MS. The results showed that there were four phospholipid classes comprising 81 molecular species with plenty of polyunsaturated fatty acyl chains observed. The formulated feed group owned the highest content of phospholipids (332.91 μg·mg^-1), followed by the frozen trash fish group (294.74 μg·mg^-1) and mixed feed group (279.74 μg·mg^-1). The effect of feeding modes was compared statistically, and the most contributing variables of m/z 802 (PC 34:2), m/z 846 (ether PC o-38:1), m/z 792 (PE 40:5), etc. were screened out and verified. The phospholipidomics results indicated that the formulated feed could replace frozen trash fish for the cultivation of P. trituberculatus.

Kefir metabolites in a fly model for Alzheimer's disease

Alzheimer's Disease (AD) is the most common cause of dementia among elderly individuals worldwide, leading to a strong motor-cognitive decline and consequent emotional distress and codependence. It is traditionally characterized by amyloidogenic pathway formation of senile plaques, and recent studies indicate that dysbiosis is also an important factor in AD's pathology. To overcome dysbiosis, probiotics-as kefir-have shown to be a great therapeutic alternative for Alzheimer's disease. In this present work, we explored kefir as a probiotic and a metabolite source as a modulator of microbiome and amyloidogenic pathway, using a Drosophila melanogaster model for AD (AD-like flies). Kefir microbiota composition was determined through 16S rRNA sequencing, and the metabolome of each fraction (hexane, dichloromethane, ethyl acetate, and n-butanol) was investigated. After treatment, flies had their survival, climbing ability, and vacuolar lesions accessed. Kefir and fraction treated flies improved their climbing ability survival rate and neurodegeneration index. In conclusion, we show that kefir in natura, as well as its fractions may be promising therapeutic source against AD, modulating amyloidogenic related pathways.

Neuroprotective effects of Scallop-derived plasmalogen in a mouse model of ischemic stroke

Scallop-derived plasmalogen (sPlas) has both anti-oxidative and anti-inflammation activities, but its efficacy has not been investigated in ischemic stroke models where oxidative stress, inflammation, and neurovascular unit (NVU) damage accelerates pathophysiological progression. Therefore, in the present study, we aimed to assess the neuroprotective effects of sPlas in ischemic stroke by using a transient middle cerebral artery occlusion (tMCAO) mouse model. After the pretreatment of vehicle or sPlas (10 mg/kg/day) for 14 days, adult male mice were subjected to tMCAO for 60 min, then continuously treated with vehicle or sPlas during reperfusion and for an additional 5 days. The administration of sPlas significantly improved motor deficits (corner and rotarod tests, *p < 0.05 vs vehicle), enhanced serum antioxidative activity (OXY-adsorbent and d-ROMs tests, *p < 0.05 vs vehicle), reduced infarction volume (*p < 0.05 vs vehicle), decreased the expression of two oxidative stress markers, 4-HNE (*p < 0.05 vs vehicle) and 8-OHdG (*p < 0.05 vs vehicle), decreased the expression of pro-inflammatory markers Iba-1 (**p < 0.01 vs vehicle), IL-1β (**p < 0.01 vs vehicle), and TNF-α (**p < 0.01 vs vehicle), and alleviated NVU damage (collagen IV, MMP9, and GFAP/collagen IV, *p < 0.05 vs vehicle). Our present findings are the first to demonstrate the neuroprotective effects of sPlas on acute ischemic stroke mice at 5 d after tMCAO via anti-oxidative stress, anti-inflammation, and improvement of NVU damage, suggesting the potential of sPlas in preventing and treating ischemic stroke.

Plasmalogen attenuates the development of hepatic steatosis and cognitive deficit through mechanism involving p75NTR inhibition

Emerging evidence suggests that the reduction of ethanolamine plasmalogen (PlsEtn) is associated with in Alzheimer's disease and metabolic diseases. However, the mechanistic bases for PlsEtn on the these diseases are not well understood. Plasmalogens are primarily synthesized in the liver and enriched in brain. To this end, the present study sought to investigate the potential role of PlsEtn on steatohepatitis and memory impairments and its underlying mechanism. Here we show that peroxisome dysfunction and impairment of PlsEtn synthesis pathway occurs in both of hippocampus and liver, resulting in the decrease of PlsEtn level in APP/PS1 mice and HFD-fed mice. shGNPAT induced PlsEtn deficiency in hepatocytes induces p75NTR enhancement leading to decreased lipolysis activity, thereby exacerbating steatosis. Moreover, in the brain, PlsEtn administration appears to not only improve steatosis but also prevent Alzheimer's disease through restoration of TrkA/p75NTR balance. Together, our findings reveal a molecular mechanistic insight into the preventive role of plasmalogen modulation against steatosis and memory impairments via p75NTR inhibition.

•

Peroxisome dysfunction and impairment of plasmalogen synthesis pathway resulted in the decrease of plasmalogen level.

•

Plasmalogen deficiency in hepatocytes induces p75NTR enhancement leading to decreased lipolysis activity.

•

Ethanolamine plasmalogen administration improves memory impairments by restoration of TrkA/p75NTR balance.

•

Ethanolamine plasmalogen administration attenuates neurodegeneration and neuronal death, and mitigates oxidative stress.

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.

Differences in oxidative susceptibilities between glycerophosphocholine and glycerophosphoethanolamine in dried scallop (Argopecten irradians) adductor muscle during storage: an oxidation kinetic assessment

BACKGROUND

Phospholipids, the main lipid component in marine shellfish, mainly comprise glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE). GPC and GPE in marine shellfish, especially scallop, carry n-3 long-chain polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), although different types of glycerophospholipids (GP) have different health benefits on human health. Moreover, different GP subclasses such as GPC and GPE have different oxidative susceptibilities in complex food systems. The present study compared the oxidative susceptibilities of GPC and GPE in dried scallop during storage by high-performance liquid chromatography-tandem mass spectrometry and kinetic models, and also investigated the effects of natural phenolic antioxidant on their susceptibilities.

RESULTS

The results showed that GPC and GPE molecular species (carrying EPA or DHA) contents in samples continuously reduced during storage at two different temperatures. The first-order kinetic model better reflected the changes of GPC and GPE molecular species (carrying EPA or DHA) in samples than the zero-order kinetic model during storage. According to the oxidation rate (k) obtained from first-order kinetic models, GPE possessed a greater oxidation rate than GPC during storage. Moreover, the results showed that antioxidants of bamboo leaves (AOB, polar polyphenolic antioxidants) significantly decreased the oxidation rates of GPC and GPE molecular species (carrying EPA or DHA) in samples during storage, and GPC could be more effectively protected by AOB compared to GPE.

CONCLUSION

The present study provides a practical method for accurately evaluating the oxidative susceptibility of different phospholipid classes in complex food systems. © 2020 Society of Chemical Industry.

Reduced gonadotroph stimulation by ethanolamine plasmalogens in old bovine brains

Ethanolamine plasmalogens (EPls), unique alkenylacyl-glycerophospholipids, are the only known ligands of G-protein-coupled receptor 61—a novel receptor co-localised with gonadotropin-releasing hormone receptors on anterior pituitary gonadotrophs. Brain EPl decreases with age. Commercial EPl—extracted from the cattle brain (unidentified age)—can independently stimulate FSH secretion from gonadotrophs. We hypothesised that there exists an age-related difference in the quality, quantity, and ability of bovine brain EPls to stimulate bovine gonadotrophs. We compared the brains of young (about 26 month old heifers) and old (about 90 month old cows) Japanese Black bovines, including EPls obtained from both groups. Additionally, mRNA expressions of the EPl biosynthesis enzymes, glyceronephosphate O-acyltransferase, alkylglycerone phosphate synthase, and fatty acyl-CoA reductase 1 (FAR1) were evaluated in young and old hypothalami. The old-brain EPl did not stimulate FSH secretion from gonadotrophs, unlike the young-brain EPl. Molecular species of EPl were compared using two-dimensional liquid chromatography-mass spectrometry. We identified 20 EPl molecular species of which three and three exhibited lower (P < 0.05) and higher (P < 0.05) ratios, respectively, in old compared to young brains. In addition, quantitative reverse transcription-polymerase chain reaction detected higher FAR1 levels in the POA, but not in the ARC&ME tissues, of old cows than that of fertile young heifers. Therefore, old-brain EPl may be associated with age-related infertility.

Plasmalogen-Based Liquid Crystalline Multiphase Structures Involving Docosapentaenoyl Derivatives Inspired by Biological Cubic Membranes

Structural properties of plasmenyl-glycerophospholipids (plasmalogens) have been scarcely studied for plasmalogens with long polyunsaturated fatty acid (PUFA) chains, despite of their significance for the organization and functions of the cellular membranes. Elaboration of supramolecular assemblies involving PUFA-chain plasmalogens in nanostructured mixtures with lyotropic lipids may accelerate the development of nanomedicines for certain severe pathologies (e.g., peroxisomal disorders, cardiometabolic impairments, and neurodegenerative Alzheimer's and Parkinson's diseases). Here, we investigate the spontaneous self-assembly of bioinspired, custom-produced docosapentaenoyl (DPA) plasmenyl (ether) and ester phospholipids in aqueous environment (pH 7) by synchrotron small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM). A coexistence of a liquid crystalline primitive cubic Im3m phase and an inverted hexagonal (H_II) phase is observed for the DPA-ethanolamine plasmalogen (C16:1p-22:5n6 PE) derivative. A double-diamond cubic Pn3m phase is formed in mixed assemblies of the phosphoethanolamine plasmalogen (C16:1p-22:5n6 PE) and monoolein (MO), whereas a coexistence of cubic and lamellar liquid crystalline phases is established for the DPA-plasmenyl phosphocholine (C16:1p-22:5n6 PC)/MO mixture at ambient temperature. The DPA-diacyl phosphoinositol (22:5n6-22:5n6 PI) ester lipid displays a propensity for a lamellar phase formation. Double membrane vesicles and multilamellar onion topologies with inhomogeneous distribution of interfacial curvature are formed upon incorporation of the phosphoethanolamine plasmalogen (C16:1p-22:5n6 PE) into dioleoylphosphocholine (DOPC) bilayers. Nanoparticulate formulations of plasmalogen-loaded cubosomes, hexosomes, and various multiphase cubosome- and hexosome-derived architectures and mixed type nano-objects (e.g., oil droplet-embedding vesicles or core-shell particles with soft corona) are produced with PUFA-chain phospholipids and lipophilic antioxidant-containing membrane compositions that are characterized by synchrotron SAXS and cryo-TEM imaging. The obtained multiphase nanostructures reflect the changes in the membrane curvature induced by the inclusion of DPA-based PE and PC plasmalogens, as well as DPA-PI ester derivative, and open new opportunities for exploration of these bioinspired nanoassemblies.

The Potential for Phospholipids in the Treatment of Airway Inflammation: An Unexplored Solution

Asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF) are major inflammatory respiratory diseases. Current mainstay therapy for asthma, and chronic obstructive pulmonary disease are corticosteroids, which have well-established side effect profiles. Phospholipids (PLs) are ubiquitous, diverse compounds with varying functions such as their structural role incell membrane, energy storage, and cell signaling.Recent advances in understanding PLs role as inflammatory mediators in the body as well as their widespread long-standing use as carrier molecules in drug delivery demonstrate the potential application of phospholipids in modulating inflammatory conditions. This review briefly explains the main mechanisms of inflammation in chronic respiratory diseases, currentanti-inflammatory treatments and areas of unmet need. The structural features, roles of endogenous and exogenous phospholipids, including their use as pharmaceutical excipients are reviewed. Current research on the immunomodulatory properties of PLs and their potentialapplication in inflammatory diseasesis the major section of this review. Considering the roles of PLs as inflammatory mediators and their safety profile established in pharmaceutical formulations, these small molecules demonstrate great potential as candidates in respiratory inflammation. Future studies need to focus on the immunomodulatory properties and the underlying mechanisms of phospholipids in respiratory inflammatory diseases.

Short-term supplementation of DHA as phospholipids rather than triglycerides improve cognitive deficits induced by maternal omega-3 PUFA deficiency during the late postnatal stage

Cognitive deficiencies, which are caused by maternal omega-3 PUFA deficiency (O-3 Def), are likely to be more rapidly and easily reversed at younger ages with quicker DHA reversal. This study aims to compare the efficiency of short-term supplementation of DHA in the form of phospholipids (PL) and triglycerides (TG) and improve cognitive deficiency in the O-3 Def model during different periods of brain development (3-week and 7-week old). The animal's spatial task performance, brain PUFA concentration, histopathology, and expression of synapse-associated proteins in the hippocampus were then analyzed. We demonstrate here that DHA-PL shows improved efficiency in improving cognitive deficiency compared to DHA-TG, particularly for adult O-3 Def offspring. The superiority of DHA-PL also correlates with the specific elevation of synapse-associated proteins, including BDNF, DCX, GAP-43, Syn, and PSD95, except to higher brain DHA accretion. This work highlights the DHA-PL as a better DHA supplement for inferior brain development caused by maternal O-3 Def, especially regarding those who missed the optimal time window of neurodevelopment.

Ethanolamine: A Potential Promoiety with Additional Effects in the Brain

Ethanolamine is a bioactive molecule found in several cells, including those in the central nervous system (CNS). In the brain, ethanolamine and ethanolamine-related molecules have emerged as prodrug moieties that can promote drug movement across the blood-brain barrier. This improvement in the ability to target drugs to the brain may also mean that in the process ethanolamine concentrations in the brain are increased enough for ethanolamine to exert its own neurological ac-tions. Ethanolamine and its associated products have various positive functions ranging from cell signaling to molecular storage, and alterations in their levels have been linked to neurodegenerative conditions such as Alzheimer's disease. This mini-review focuses on the effects of ethanolamine in the CNS and highlights the possible implications of these effects for drug design.

APOE Genotype Differentially Modulates Plasma Lipids in Healthy Older Individuals, with Relevance to Brain Health

Apolipoprotein E (APOE) genotype is an established genetic risk factor for sporadic Alzheimer's disease (AD) but the extent to which APOE genotype influences the plasma lipidome is unknown, even though lipids are potential diagnostic or prognostic biomarkers for AD. We quantified plasma lipids using untargeted liquid chromatography coupled mass spectrometry in a total of 152 non-demented participants aged 65-100 years carrying at least one ɛ2 or ɛ4 allele (ɛ2/ɛ2 or ɛ2/ɛ3, n = 38: ɛ4/ɛ3 or ɛ4/ɛ4, n = 38), who were roughly matched to an ɛ3/ɛ3 control by age, sex, and lipid-lowering medication (n = 76). Low density lipoprotein cholesterol levels were genotype dependent (ɛ4/ɛ4> ɛ4/ɛ3> ɛ3/ɛ3> ɛ2/ɛ3> ɛ2/ɛ2). The greatest variation in lipids was related to the ɛ2 isoform, where various lysophosphatidylcholines and all phosphatidylethanolamine (PE) subclasses were elevated relative to ɛ3/ɛ3 and ɛ4 carriers. APOEɛ4 carriers had reduced phosphatidylinositol relative to ɛ3/ɛ3 and ɛ2 carriers. Logistic regression revealed that ɛ2 carriers were at least 4 times higher odds of being in the highest tertile of PE lipid level relative to ɛ3/ɛ3. The elevation in PE and other phospholipids in ɛ2 carriers may indicate the protective effect of ɛ2 is linked to these phospholipids. Additionally, high baseline PE in cognitively normal participants predicted protection against cognitive decline six years later. Our data suggest substantial modulation of plasma lipids by APOE genotype and therefore indicates possible lipid targets and pathomechanisms involved in AD risk.

Plasmalogens, platelet-activating factor and beyond - Ether lipids in signaling and neurodegeneration

Glycerol-based ether lipids including ether phospholipids form a specialized branch of lipids that in mammals require peroxisomes for their biosynthesis. They are major components of biological membranes and one particular subgroup, the plasmalogens, is widely regarded as a cellular antioxidant. Their vast potential to influence signal transduction pathways is less well known. Here, we summarize the literature showing associations with essential signaling cascades for a wide variety of ether lipids, including platelet-activating factor, alkylglycerols, ether-linked lysophosphatidic acid and plasmalogen-derived polyunsaturated fatty acids. The available experimental evidence demonstrates links to several common players like protein kinase C, peroxisome proliferator-activated receptors or mitogen-activated protein kinases. Furthermore, ether lipid levels have repeatedly been connected to some of the most abundant neurological diseases, particularly Alzheimer's disease and more recently also neurodevelopmental disorders like autism. Thus, we critically discuss the potential role of these compounds in the etiology and pathophysiology of these diseases with an emphasis on signaling processes. Finally, we review the emerging interest in plasmalogens as treatment target in neurological diseases, assessing available data and highlighting future perspectives. Although many aspects of ether lipid involvement in cellular signaling identified in vitro still have to be confirmed in vivo, the compiled data show many intriguing properties and contributions of these lipids to health and disease that will trigger further research.

Dietary PlsEtn Ameliorates Colon Mucosa Inflammatory Stress and ACF in DMH-Induced Colon Carcinogenesis Mice: Protective Role of Vinyl Ether Linkage

Ethanolamine plasmalogen (PlsEtn), a sub-class of ethanolamine glycerophospholipids (EtnGpl), is a universal phospholipid in mammalian membranes. Several researchers are interested in the relationship between colon carcinogenesis and colon PlsEtn levels. Here, we evaluated the functional role of dietary purified EtnGpl from the ascidian muscle (87.3 mol% PlsEtn in EtnGpl) and porcine liver (7.2 mol% PlsEtn in EtnGpl) in 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) in vivo, and elucidated the possible underlying mechanisms behind it. Dietary EtnGpl-suppressed DMH-induced aberrant crypt with one foci (AC1) and total ACF formation (P < 0.05). ACF suppression by dietary ascidian muscle EtnGpl was higher compared with dietary porcine liver EtnGpl. Additionally, dietary EtnGpl decreased DMH-induced oxidative damage, overproduction of TNF-α, and expression of apoptosis-related proteins in the colon mucosa. The effect of dietary ascidian muscle EtnGpl showed superiority compared with dietary porcine liver EtnGpl. Our results demonstrate the mechanisms by which dietary PlsEtn suppress ACF formation and apoptosis. Dietary PlsEtn attained this suppression by reducing colon inflammation and oxidative stress hence a reduction in DMH-induced intestinal impairment. These findings provide new insights about the functional role of dietary PlsEtn during colon carcinogenesis.

Quantitative and comparative study of plasmalogen molecular species in six edible shellfishes by hydrophilic interaction chromatography mass spectrometry

Shellfishes contain plasmalogens correlating to the functions of brain, heart, etc. Herein, a mild acid hydrolysis and hydrophilic interaction chromatography (HILIC) tandem mass spectrometry method was developed for analyzing plasmalogens in six shellfish species. A total of 19 plasmalogen molecular species were successfully identified, including nine phosphatidylcholine plasmalogen (plasPC), seven phosphatidylethanolamine plasmalogen (plasPE), and three phosphatidylserine plasmalogen (plasPS). The quantitative results indicated that mussel (32 μg·mg^-1) possessed the highest content of plasmalogens, followed by oyster (21 μg·mg^-1) and razor clam (15 μg·mg^-1). The statistic models showed that the plasPE P-18:0/20:5 (m/z 748), plasPE P-16:0/22:2 & P-18:0/20:2 (m/z 754) and plasPS were the most contributing difference between shellfishes. The results indicated that this method was sensitive and precise to determine plasmalogens in shellfish, and mussel was demonstrated to be a good choice for the large-scale preparation of plasmalogens.

The exogenous natural phospholipids, EPA-PC and EPA-PE, contribute to ameliorate inflammation and promote macrophage polarization

Dietary intake of sea cucumber phospholipids, a rich source of eicosapentaenoic acid in the form of phospholipids (EPA-PLs), has been shown to improve obesity and related disorders. However, whether dietary eicosapentaenoic acid in the form of phosphatidylcholine and phosphatidylethanolamine (EPA-PC and EPA-PE, respectively) shows anti-inflammatory efficacy and its underlying mechanism has scarcely been investigated to date. Thus, the purpose of this study was to determine if EPA-PC and EPA-PE improve chronic inflammation and alter the interaction between macrophages and adipocytes. We found that EPA-PC and EPA-PE reduced the elevated levels of serum TNF-α, IL-6 and MCP1 and attenuated macrophage infiltration in the liver and iWAT of an HFSD-induced inflammatory model. Importantly, EPA-PC and EPA-PE promoted macrophage polarization in white adipose tissue. Furthermore, this effect on macrophage polarization was also observed in a 3T3L1 and Raw 264.7 Transwell co-culture system, which suggests that EPA-PC and EPA-PE attenuate chronic inflammation by promoting the M2-dominant polarization of macrophages in vitro. Our experiments in vitro illustrated that EPA-PC and EPA-PE attenuated the phosphorylation of p65 NFκB in Raw264.7 macrophages and increased PPARγ expression in 3T3-L1 adipocytes during the co-culture, which may contribute to the improvement in adipose inflammation. Thus, dietary eicosapentaenoic acid in the form of phosphatidylcholine and phosphatidylethanolamine may be a therapeutic strategy for chronic inflammation in obese adipose tissue.

Roles of endogenous ether lipids and associated PUFAs in the regulation of ion channels and their relevance for disease

Ether lipids (ELs) are lipids characterized by the presence of either an ether linkage (alkyl lipids) or a vinyl ether linkage [i.e., plasmalogens (Pls)] at the sn1 position of the glycerol backbone, and they are enriched in PUFAs at the sn2 position. In this review, we highlight that ELs have various biological functions, act as a reservoir for second messengers (such as PUFAs) and have roles in many diseases. Some of the biological effects of ELs may be associated with their ability to regulate ion channels that control excitation-contraction/secretion/mobility coupling and therefore cell physiology. These channels are embedded in lipid membranes, and lipids can regulate their activities directly or indirectly as second messengers or by incorporating into membranes. Interestingly, ELs and EL-derived PUFAs have been reported to play a key role in several pathologies, including neurological disorders, cardiovascular diseases, and cancers. Investigations leading to a better understanding of their mechanisms of action in pathologies have opened a new field in cancer research. In summary, newly identified lipid regulators of ion channels, such as ELs and PUFAs, may represent valuable targets to improve disease diagnosis and advance the development of new therapeutic strategies for managing a range of diseases and conditions.

EPA-enriched ethanolamine plasmalogen and EPA-enriched phosphatidylethanolamine enhance BDNF/TrkB/CREB signaling and inhibit neuronal apoptosis in vitro and in vivo

Our previous study showed that EPA-enriched ethanolamine plasmalogen (EPA-pPE) exerted more significant effects than EPA-enriched phosphatidylethanolamine (EPA-PE) in improving learning and memory deficit. However, the results of the mechanism study were not consistent with the improved cognitive function, which suggested that other signaling pathways might be involved. In the present study, primary cultured hippocampal neurons and cognitive deficiency rats were used to compare the effects of EPA-pPE and EPA-PE on brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB)/cAMP response element-binding protein (CREB) signaling and neuronal apoptosis. The in vitro experiment showed that both EPA-pPE and EPA-PE could relieve cell death and improve the cellular morphology of neurons via upregulating anti-apoptotic proteins and downregulating pro-apoptotic proteins. The in vivo experiment showed that EPA-pPE exerted more significant effects than EPA-PE in improving the number of neuronal Nissl bodies, increasing the branching of dendrites and dendritic spine density in cortical neurons, as well as improving the expression of synaptic vesicle-related proteins synaptophysin (SYN) and PSD95 via BDNF/TrkB/CREB signaling. These results indicated that EPA-pPE exerted neuroprotection at least partly through inhibiting neuronal apoptosis and enhancing the BDNF/TrkB/CREB pathway, which suggests that EPA-enriched plasmalogen can be explored as a potential therapeutic agent in long-term Alzheimer's disease therapy.

Oral administration of a synthetic vinyl-ether plasmalogen normalizes open field activity in a mouse model of rhizomelic chondrodysplasia punctata

Rhizomelic chondrodysplasia punctata (RCDP) is a rare genetic disorder caused by mutations in peroxisomal genes essential for plasmalogen biosynthesis. Plasmalogens are a class of membrane glycerophospholipids containing a vinyl-ether-linked fatty alcohol at the sn-1 position that affect functions including vesicular transport, membrane protein function and free radical scavenging. A logical rationale for the treatment of RCDP is therefore the therapeutic augmentation of plasmalogens. The objective of this work was to provide a preliminary characterization of a novel vinyl-ether synthetic plasmalogen, PPI-1040, in support of its potential utility as an oral therapeutic option for RCDP. First, wild-type mice were treated with ¹³C₆-labeled PPI-1040, which showed that the sn-1 vinyl-ether and the sn-3 phosphoethanolamine groups remained intact during digestion and absorption. Next, a 4-week treatment of adult plasmalogen-deficient Pex7^hypo/null mice with PPI-1040 showed normalization of plasmalogen levels in plasma, and variable increases in plasmalogen levels in erythrocytes and peripheral tissues (liver, small intestine, skeletal muscle and heart). Augmentation was not observed in brain, lung and kidney. Functionally, PPI-1040 treatment normalized the hyperactive behavior observed in the Pex7^hypo/null mice as determined by open field test, with a significant inverse correlation between activity and plasma plasmalogen levels. Parallel treatment with an equal amount of ether plasmalogen precursor, PPI-1011, did not effectively augment plasmalogen levels or reduce hyperactivity. Our findings show, for the first time, that a synthetic vinyl-ether plasmalogen is orally bioavailable and can improve plasmalogen levels in an RCDP mouse model. Further exploration of its clinical utility is warranted.

This article has an associated First Person interview with the joint first authors of the paper.

Summary: This article shows, for the first time, that a synthetic vinyl-ether plasmalogen is orally bioavailable and bioactive in vivo following administration in animals.

Eicosapentaenoic Acid-Enriched Phosphatidylcholine Mitigated Aβ1-42-Induced Neurotoxicity via Autophagy-Inflammasome Pathway

Recent studies indicated that neuroinflammation contributes to the exacerbation of Alzheimer's disease (AD) and plays an important role in AD. The NOD-like receptor protein 3 (NLRP3) inflammasome, which is an important component of innate immune system, is associated with a wide range of human central nervous system disorders, including AD. Most of the studies focus on the protective effects of docosahexaenoic acid (DHA) in AD, but eicosapentaenoic acid (EPA) has rarely been involved. Here, we investigate the effects of EPA in the forms of phosphatidylcholine (EPA-PC) and ethyl esters (EPA-EE) in improving Aβ1-42-induced neurotoxicity. The spatial memory ability and the biochemical changes in the hippocampus were measured, including glial cell activation, tumor necrosis factor α production, NLRP3 inflammasome activation, and autophagic flux. The present results showed that the AD rats were significantly protected from spatial memory loss by the supplementation (EPA + DHA = 60 mg/kg, i.g., 20 days) of EPA-PC, while EPA-EE showed no significant benefit. Further mechanism studies suggested that EPA-PC could inhibit Aβ-induced neurotoxicity by alleviating NLRP3 inflammasome activation and enhancing autophagy. These findings indicate that EPA could improve cognitive deficiency in Aβ1-42-induced AD rats via autophagic inflammasomal pathway and the bioactivity differs in its molecular form.

Marine omega-3 (n-3) phospholipids: A comprehensive review of their properties, sources, bioavailability, and relation to brain health

For several decades, there has been considerable interest in marine-derived long chain n-3 fatty acids (n-3 LCPUFAs) due to their outstanding health benefits. n-3 LCPUFAs can be found in nature either in triglycerides (TAGs) or in phospholipid (PL) form. From brain health point of view, PL n-3 is more bioavailable and potent compared to n-3 in TAG form, as only PL n-3 is able to cross the blood-brain barrier and can be involved in brain biochemical reactions. However, PL n-3 has been ignored in the fish oil industry and frequently removed as an impurity during degumming processes. As a result, PL products derived from marine sources are very limited compared to TAG products. Commercially, PLs are being used in pharmaceutical industries as drug carriers, in food manufacturing as emulsifiers and in cosmetic industries as skin care agents, but most of the PLs used in these applications are produced from vegetable sources that contain less (without EPA, DPA, and DHA) or sometimes no n-3 LCPUFAs. This review provides a comprehensive account of the properties, structures, and major sources of marine PLs, and provides focussed discussion of their relationship to brain health. Epidemiological, laboratory, and clinical studies on n-3 LCPUFAs enriched PLs using different model systems in relation to brain and mental health that have been published over the past few years are discussed in detail.

Digestion, Absorption, and Metabolism Characteristics of EPA-Enriched Phosphoethanolamine Plasmalogens Based on Gastrointestinal Functions in Healthy Mice

EPA-enriched phosphoethanolamine plasmalogens (EPA-pPE), widely present in marine creatures, is a unique glycerophospholipid with EPA at the sn-2 position of the glycerol backbone. EPA-pPE has been reported to exhibit numerous distinctive bioactivities. However, the digestion, absorption, and metabolism characteristics of EPA-pPE in vivo are not clear, which restrict the molecular mechanism analysis related to its distinctive activities. The aim of the present study was to illustrate the digestion, absorption, and metabolism characteristics of EPA-pPE by lipid analysis in serum, intestinal wall, and content after oral administration of EPA-pPE emulsion. Results showed the EPA percentage of total fatty acids in serum was increasing over time, with two peaks at 5 and 10 h by 1.89 ± 0.2 and 2.58 ± 0.27, respectively, and then fell from 1.89 ± 0.17 at 10 h to 1.35 ± 0.16 at 16 h. In small intestinal content, EPA-pPE was hydrolyzed to lyso-phospholipids and EPA by phospholipases A2 and the vinyl ether bond was retained at the sn-1 position. The released EPA could be quickly taken up into the enterocytes and enter circulation. The comparison of simulated digestion in vitro showed that the distinct digestion and absorption process of EPA-pPE was a unique phenomenon. EPA could be retained in serum at a high level for a substantial period of time, which suggested that EPA-pPE was not just a short-lived circulating molecule.