Age-dependent changes in nervonic acid-containing sphingolipids in mouse hippocampus

Discovering Novel Plasma Biomarkers for Ischemic Stroke: Lipidomic and Metabolomic Analyses in an Aged Mouse Model

Ischemic stroke remains a leading cause of mortality and long-term disability worldwide, necessitating efforts to identify biomarkers for diagnosis, prognosis, and treatment monitoring. The present study aimed to identify novel plasma biomarkers of neurodegeneration and inflammation in a mouse model of stroke induced by distal middle cerebral artery (MCA) occlusion. Using targeted lipidomic and global untargeted metabolomic profiling of plasma collected from aged male mice 24 hours after stroke and weekly thereafter for 7 weeks, we discovered distinct acute and chronic signatures. In the acute phase, we observed elevations in myelin-associated lipids, including sphingomyelin (SM) and hexosylceramide (HCER) lipid species, indicating brain lipid catabolism. In the chronic phase, we identified 12-hydroxyeicosatetraenoic acid (12-HETE) as a putative biomarker of prolonged inflammation, consistent with our previous observation of a biphasic pro-inflammatory response to ischemia in the mouse brain. These results provide insight into the metabolic alterations detectable in the plasma after stroke and highlight the potential of myelin degradation products and arachidonic acid derivatives as biomarkers of neurodegeneration and inflammation, respectively. These discoveries lay the groundwork for further validation in human studies and may improve stroke management strategies.

Serotonin Signaling through Lipid Membranes

Serotonin (5-HT) is a vital modulatory neurotransmitter responsible for regulating most behaviors in the brain. An inefficient 5-HT synaptic function is often linked to various mental disorders. Primarily, membrane proteins controlling the expression and activity of 5-HT synthesis, storage, release, receptor activation, and inactivation are critical to 5-HT signaling in synaptic and extra-synaptic sites. Moreover, these signals represent information transmission across membranes. Although the lipid membrane environment is often viewed as fairly stable, emerging research suggests significant functional lipid-protein interactions with many synaptic 5-HT proteins. These protein-lipid interactions extend to almost all the primary lipid classes that form the plasma membrane. Collectively, these lipid classes and lipid-protein interactions affect 5-HT synaptic efficacy at the synapse. The highly dynamic lipid composition of synaptic membranes suggests that these lipids and their interactions with proteins may contribute to the plasticity of the 5-HT synapse. Therefore, this broader protein-lipid model of the 5-HT synapse necessitates a reconsideration of 5-HT's role in various associated mental disorders.

UPLC-Q-TOF/MS based serum and urine metabolomics strategy to analyze the mechanism of nervonic acid in treating Alzheimer's disease

Nervonic acid is a natural component of breast milk and is frequently used as a food additive due to its excellent neuroprotective effects. Although it has been reported that nervonic acid may play a role in the recovery of human cognitive impairment, its specific mechanism of action is still unclear. In this study, the results of serum biochemical indexes showed that nervonic acid improved inflammation and reduced amyloid β peptide (Aβ) deposition and tau protein phosphorylation in Alzheimer's disease (AD) rats. Subsequently, we further used a metabolomics approach to investigate the potential mechanism of action of nervonic acid in the treatment of AD. The results of serum and urine metabolomics study showed that the intervention of nervonic acid significantly reversed the metabolic profile disorder in AD rats. A total of 52 metabolites were identified. They mainly involved linoleic acid metabolism, alpha-linolenic acid metabolism, phenylalanine metabolism and arachidonic acid metabolism, and all these metabolic pathways were associated with the emergence of inflammation in vivo. It suggests that the therapeutic effect of nervonic acid on AD is likely to be produced by ameliorating inflammation. The results obtained in this study provide new insights into the mechanism of nervonic acid treatment of AD and lay a foundation for the clinical application of nervonic acid in the treatment of Alzheimer's disease.

Brain areas lipidomics in female transgenic mouse model of Alzheimer's disease

Lipids are the major component of the brain with important structural and functional properties. Lipid disruption could play a relevant role in Alzheimer's disease (AD). Some brain lipidomic studies showed significant differences compared to controls, but few studies have focused on different brain areas related to AD. Furthermore, AD is more prevalent in females, but there is a lack of studies focusing on this sex. This work aims to perform a lipidomic study in selected brain areas (cerebellum, amygdala, hippocampus, entire cortex) from wild-type (WT, n = 10) and APPswe/PS1dE9 transgenic (TG, n = 10) female mice of 5 months of age, as a model of early AD, to identify alterations in lipid composition. A lipidomic mass spectrometry-based method was optimized and applied to brain tissue. As result, some lipids showed statistically significant differences between mice groups in cerebellum (n = 68), amygdala (n = 49), hippocampus (n = 48), and the cortex (n = 22). In addition, some lipids (n = 15) from the glycerolipid, phospholipid, and sphingolipid families were statistically significant in several brain areas simultaneously between WT and TG. A selection of lipid variables was made to develop a multivariate approach to assess their discriminant potential, showing high diagnostic indexes, especially in cerebellum and amygdala (sensitivity 70-100%, sensibility 80-100%).

De novo synthesis of nervonic acid and optimization of metabolic regulation by Yarrowia lipolytica

Nervonic acid, a natural fatty acid compound and also a core component of nerve fibers and nerve cells, has been widely used to prevent and treat related diseases of the brain nervous system. At present, fatty acids and their derivatives are mainly obtained by natural extraction or chemical synthesis which are limited by natural resources and production costs. In this study, the de novo synthetic pathway of nervonic acid was constructed in Yarrowia lipolytica by means of synthetic biology, and the yield of nervonic acid was further improved by metabolic engineering and fermentation optimization. Specially, heterologous elongases and desaturases derived from different organism were successfully expressed and evaluated for their potential for the production of nervonic acid in Y. lipolytica. Meanwhile, we overexpressed the genes involved in the lipid metabolism to increase the nervonic acid titer to 111.6 mg/L. In addition, the potential of adding oil as auxiliary carbon sources for nervonic acid production by the engineered Y. lipolytica was analyzed. The results indicated that supplementation with colleseed oil as an auxiliary carbon source can be beneficial for the nervonic acid productivity, which led to the highest concentration of 185.0 mg/L in this work. To summarize, this study describes that the Y. lipolytica can be used as a promising platform for the production of nervonic acid and other very long-chain fatty acids.

Nervonic acid reduces the cognitive and neurological disturbances induced by combined doses of D-galactose/AlCl3 in mice

Nervonic acid (NA) is a kind of ultra-long-chain monounsaturated fatty acid, which can repair nerve cell damage caused by oxidative stress. Alzheimer's disease (AD) is a nervous system disease and often accompanied by the decline of learning and memory capacity. In this study, the combined dose of D-galactose/AlCl3 was used to establish a mouse model of AD. Meanwhile, the mice were treated with different doses of NA (10.95 and 43.93 mg/kg). The results showed that NA delayed the decline of locomotion and learning ability caused by D-galactose/AlCl3, increased the activity of total superoxide dismutase, catalase, glutathione peroxidase, and reduced the content of malondialdehyde in vivo. Besides, NA reduced the levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), aspartate aminotransferase, alanine aminotransferase, increased the levels of 5-hydroxytryptamine, dopamine, γ-aminobutyric acid, alleviated the cell morphology damage induced by D-galactose/AlCl3 in hippocampus and liver tissue. Furthermore, the intervention of NA upregulated the expression levels of PI3K, AKT, and mTOR genes and downregulated the expression levels of TNF-α, IL-6, and IL-1β genes. Therefore, we speculate the intervention of NA could be an effective way in improving cognitive impairment through the activation of PI3K signaling pathway. These results suggest that NA has the potential to be developed as antioxidant drug for the prevention and early therapy of AD.

The major TMEM106B dementia risk allele affects TMEM106B protein levels, fibril formation, and myelin lipid homeostasis in the ageing human hippocampus

BACKGROUND

The risk for dementia increases exponentially from the seventh decade of life. Identifying and understanding the biochemical changes that sensitize the ageing brain to neurodegeneration will provide new opportunities for dementia prevention and treatment. This study aimed to determine how ageing and major genetic risk factors for dementia affect the hippocampal proteome and lipidome of neurologically-normal humans over the age of 65. The hippocampus was chosen as it is highly susceptible to atrophy with ageing and in several neurodegenerative diseases.

METHODS

Mass spectrometry-based proteomic and lipidomic analysis of CA1 hippocampus samples from 74 neurologically normal human donors, aged 66-104, was used in combination with multiple regression models and gene set enrichment analysis to identify age-dependent changes in the proteome and lipidome. ANOVA was used to test the effect of major dementia risk alleles in the TMEM106B and APOE genes on the hippocampal proteome and lipidome, adjusting for age, gender, and post-mortem interval. Fibrillar C-terminal TMEM106B fragments were isolated using sarkosyl fractionation and quantified by immunoblotting.

RESULTS

Forty proteins were associated with age at false discovery rate-corrected P < 0.05, including proteins that regulate cell adhesion, the cytoskeleton, amino acid and lipid metabolism, and ribosomal subunits. TMEM106B, a regulator of lysosomal and oligodendrocyte function, was regulated with greatest effect size. The increase in TMEM106B levels with ageing was specific to carriers of the rs1990622-A allele in the TMEM106B gene that increases risk for frontotemporal dementia, Alzheimer's disease, Parkinson's disease, and hippocampal sclerosis with ageing. Rs1990622-A was also associated with higher TMEM106B fibril content. Hippocampal lipids were not significantly affected by APOE genotype, however levels of myelin-enriched sulfatides and hexosylceramides were significantly lower, and polyunsaturated phospholipids were higher, in rs1990622-A carriers after controlling for APOE genotype.

CONCLUSIONS

Our study demonstrates that TMEM106B protein abundance is increased with brain ageing in humans, establishes that dementia risk allele rs1990622-A predisposes to TMEM106B fibril formation in the hippocampus, and provides the first evidence that rs1990622-A affects brain lipid homeostasis, particularly myelin lipids. Our data suggests that TMEM106B is one of a growing list of major dementia risk genes that affect glial lipid metabolism.

Combining orthogonal plant and non-plant fatty acid biosynthesis pathways for efficient production of microbial oil enriched in nervonic acid in Yarrowia lipolytica

Nervonic acid has proven efficacy in brain development and the prevention of neurodegenerative diseases. Here, an alternative and sustainable strategy for nervonic acid-enriched plant oil production was established. Different β-ketoacyl-CoA synthases and heterologous Δ15 desaturase were co-expressed, combined with the deletion of the β-oxidation pathway to construct orthogonal plant and non-plant nervonic acid biosynthesis pathways in Yarrowia lipolytica. A "block-pull-restrain" strategy was further applied to improve the supply of stearic acid as the precursor of the non-plant pathway. Then, lysophosphatidic acid acyltransferase from Malania oleifera (MoLpaat) was identified, which showed specificity for nervonic acid. Endogenous LPAAT was exchanged by MoLPAAT resulted in 17.10 % nervonic acid accumulation. Finally, lipid metabolism was engineered and cofactor supply was increased to boost the lipid accumulation in a stable null-hyphal strain. The final strain produced 57.84 g/L oils with 23.44 % nervonic acid in fed-batch fermentation, which has the potential to substitute nervonic acid-enriched plant oil.

Nervonic acid improves liver inflammation in a mouse model of Parkinson's disease by inhibiting proinflammatory signaling pathways and regulating metabolic pathways

BACKGROUND

Nervonic acid (NA) - a type of bioactive fatty acid that is found in natural sources - can inhibit inflammatory reactions and regulate immune system balance. Therefore, the use of NA for the treatment of neurodegenerative diseases has received considerable attention. Our previous study found that NA inhibited inflammatory responses in the brain of Parkinson's disease (PD) mouse models. In addition to the brain, PD is also associated with visceral organ dysfunction, especially impaired liver function. Thus, studying the role of NA in PD-mediated inflammation of the liver is particularly important.

METHODS

A combined transcriptome and metabolomic approach was utilized to investigate the anti-inflammatory effects of NA on the liver of PD mice. Inflammatory signaling molecules and metabolic pathway-related genes were examined in the liver using real-time PCR and western blotting.

RESULTS

Liver transcriptome analysis revealed that NA exerted anti-inflammatory effects by controlling several pro-inflammatory signaling pathways, such as the down-regulation of the tumor necrosis factor and nuclear factor kappa B signaling pathways, both of which were essential in the development of inflammatory disease. In addition, liver metabolomic results revealed that metabolites related to steroid hormone biosynthesis, arachidonic acid metabolism, and linoleic acid metabolism were up-regulated and those related to valine, leucine, and isoleucine degradation pathways were down-regulated in NA treatment groups compared with the PD model. The integration of metabolomic and transcriptomic results showed NA significantly exerted its anti-inflammatory function by regulating the transcription and metabolic pathways of multiple genes. Particularly, linoleic acid metabolism, arachidonic acid metabolism, and steroid hormone biosynthesis were the crucial pathways of the anti-inflammatory action of NA. Key genes in these metabolic pathways and key molecules in inflammatory signaling pathways were also verified, which were consistent with transcriptomic results.

CONCLUSION

These findings provide novel insights into the liver protective effects of NA against PD mice. This study also showed that NA could be a useful dietary element for improving and treating PD-induced liver inflammation.

Nervonic acid and its sphingolipids: Biological functions and potential food applications

Nervonic acid, a 24-carbon fatty acid with only one double bond at the 9th carbon (C24:1n-9), is abundant in the human brain, liver, and kidney. It not only functions in free form but also serves as a critical component of sphingolipids which participate in many biological processes such as cell membrane formation, apoptosis, and neurotransmission. Recent studies show that nervonic acid supplementation is not only beneficial to human health but also can improve the many medical conditions such as neurological diseases, cancers, diabetes, obesity, and their complications. Nervonic acid and its sphingomyelins serve as a special material for myelination in infants and remyelination patients with multiple sclerosis. Besides, the administration of nervonic acid is reported to reduce motor disorder in mice with Parkinson's disease and limit weight gain. Perturbations of nervonic acid and its sphingolipids might lead to the pathogenesis of many diseases and understanding these mechanisms is critical for investigating potential therapeutic approaches for such diseases. However, available studies about this aspect are limited. In this review, relevant findings about functional mechanisms of nervonic acid have been comprehensively and systematically described, focusing on four interconnected functions: cellular structure, signaling, anti-inflammation, lipid mobilization, and their related diseases.

Integrated metabolomics and transcriptomics reveal the neuroprotective effect of nervonic acid on LPS-induced AD model mice

Nervonic acid (NA) is one of the long-chain fatty acids with significant biological activity that has been widely studied in recent years. It is believed that NA may play a crucial role in the recovery of human cognitive disorders. Although many literatures have shown that NA has some neuroprotective effect in experimental animal models, the detailed neuroprotective mechanism of NA is still poorly understood. In this study, we applied behavioral, transcriptomic and metabolomic approaches to analyze the neuroprotective effect of NA and its molecular mechanism in AD (Alzheimer's disease) model mice. We demonstrated that NA improved motor skills and learning and memory abilities of mice at the behavioral level. To further understand the specific pathways involved in this protective effect, we applied the metabolomics and transcriptomics profilings and focused on the expression patterns of genes that NA might alter, particularly those related to the accumulation of metabolites in the brain. According to the results, pathways related to neuroinflammation were significantly increased in LPS (lipopolysaccharide)-induced AD mice compared with the normal control, and pathways related to neuronal growth and synaptic plasticity were significantly downregulated. When NA was used for protection, these signaling pathways induced by LPS were partially reversed. At the same time, compared with the AD model group, upregulation of arachidonic acid metabolism, purine metabolism, and primary bile acid biosynthesis and downregulation of amino acid metabolic pathways were particularly pronounced in the NA treatment group. We also verified the enzymes of some metabolic pathways were consistent with transcriptome result. In summary, our results show that NA can significantly ameliorate LPS-induced neuroinflammation and deterioration of learning and memory, and exerts a neuroprotective function through regulation of multiple gene transcription and metabolism pathways. In particular, the arachidonic acid metabolism which related to inflammation and the amino acids metabolism which related to the synthesis of neurotransmitters were most significant response to NA treatment. Our results provided the first preliminary evidences for molecular mechanism investigation of NA from a combined transcriptome and metabolome perspective.

The major TMEM106B dementia risk allele affects TMEM106B protein levels and myelin lipid homeostasis in the ageing human hippocampus

Background The risk for dementia increases exponentially from the seventh decade of life. Identifying and understanding the biochemical changes that sensitize the ageing brain to neurodegeneration will provide new opportunities for dementia prevention and treatment. This study aimed to determine how ageing and major genetic risk factors for dementia affect the hippocampal proteome and lipidome of neurologically-normal humans over the age of 65. The hippocampus was chosen as it is highly susceptible to atrophy with ageing and in several neurodegenerative diseases. Methods Mass spectrometry-based proteomic and lipidomic analysis of CA1 hippocampus samples from 74 neurologically normal human donors, aged 66-104, was used in combination with multiple regression models and gene set enrichment analysis to identify age-dependent changes in the proteome and lipidome. ANOVA was used to test the effect of major dementia risk alleles in the TMEM106B and APOE genes on the hippocampal proteome and lipidome, adjusting for age, gender, and post-mortem interval. Results Forty proteins were associated with age at false discovery rate-corrected P < 0.05, including proteins that regulate cell adhesion, the cytoskeleton, amino acid and lipid metabolism, and ribosomal subunits. Transmembrane protein 106B (TMEM106B), a regulator of lysosomal and oligodendrocyte function, was regulated with greatest effect size. The increase in TMEM106B levels with age was specific to carriers of the rs1990622-A allele in the TMEM106B gene that is associated with increased risk for frontotemporal dementia, Alzheimer's disease, Parkinson's disease, and hippocampal sclerosis with ageing. Hippocampal lipids were not significantly affected by APOE genotype, however levels of myelin-enriched sulfatides and hexosylceramides were significantly lower, and polyunsaturated phospholipids were higher, in rs1990622-A carriers after controlling for APOE genotype. Conclusions Our study provides the first evidence that TMEM106B protein abundance is increased with brain ageing in humans, and the first evidence that the major TMEM106B dementia risk allele affects brain lipid homeostasis, with a clear effect on myelin lipid content. Our data implies that TMEM106B is one of a growing list of major dementia risk genes that affect glial lipid metabolism.

Natural fish oil improves the differentiation and maturation of oligodendrocyte precursor cells to oligodendrocytes in vitro after interaction with the blood–brain barrier

The blood–brain barrier (BBB) tightly controls the microenvironment of the central nervous system (CNS) to allow neurons to function properly. Additionally, emerging studies point to the beneficial effect of natural oils affecting a wide variety of physiological and pathological processes in the human body. In this study, using an in vitro model of the BBB, we tested the influence of natural fish oil mixture (FOM) vs. borage oil (BO), both rich in long-chain polyunsaturated fatty acids (LC-PUFAs) and monounsaturated fatty acids (MUFAs) such as oleic acid (C18:1n9c) or nervonic acid (NA), on human oligodendrocyte precursor cells (hOPCs) during their maturation to oligodendrocytes (OLs) regarding their ability to synthesize myelin peptides and NA. We demonstrated that FOM, opposite to BO, supplemented endothelial cells (ECs) and astrocytes forming the BBB, affecting the function of hOPCs during their maturation. This resulted in improved synthesis of myelin basic protein (MBP), myelin oligodendrocyte glycoprotein (MOG), proteolipid protein (PLP), and NA in mature OLs. This effect is probably the result of BBB cell and hOPC stimulation via free fatty acid receptors (FFARs), which increases insulin growth factor-1 (IGF-1), ciliary neurotrophic factor (CNTF), and brain-derived neurotrophic factor (BDNF) and inhibits fibroblast growth factor 2 (FGF-2) synthesis. The unique formula of fish oil, characterized by much more varied components compared to those of BOs, also improved the enhancement of the tight junction by increasing the expression of claudin-5 and VE-cadherin on ECs. The obtained data justify consideration of naturally derived fish oil intake in human diet as affecting during remyelination.

Germplasm resources of three wood plant species enriched with nervonic acid

Nervonic acid (NA) is a very-long-chain monounsaturated fatty acid with pharmaceutical and nutraceutical functions that plays an important role in treating several neurological disorders. One major source of NA is plant seed oil. Here we report fatty acid profiles of seeds and germplasm diversity of six plant species, including three woody plants with high amounts of NA-enriched seed oil, Malania oleifera, Macaranga adenantha, and M. indica. M. oleifera had the largest seed (average 7.40 g single seed), highest oil content (58.71%), and highest NA level (42.22%). The germplasm diversity of M. oleifera is associated with its habitat but not elevation. Seeds of M. adenantha contained higher NA levels (28.41%) than M. indica (21.77%), but M. indica contained a significantly higher oil content (29.22%) and seed yield. M. adenantha germplasm varied among populations, with one population having seeds with high oil content (22.63%) and NA level (37.78%).Although M. indica grow naturally at a range of elevations, no significant differences were detected between M. indica populations. These results suggest that M. indica and M. oleifera have greater potential as a source of NA, which will contribute to constructing a germplasm resource nursery and establishing a selection and breeding program to improve the development of NA-enriched plants.

Perspectives of nervonic acid production by Yarrowia lipolytica

Nervonic acid (cis-15-tetracosenoic acid, 24:1Δ15) is a long chain monounsaturated fatty acid, mainly exists in white matt er of the human brains. It plays an important role in the development of nervous system and curing neurological diseases. The limited natural sources and high price are considered limiting factors for the extensive application of nervonic acid. Yarrowia lipolytica is a high lipid producing yeast and engineered strain which can produce nervonic acid. The biosynthesis of nervonic acid has yet to be investigated, although the metabolism has been examined for couple of years. Normally, oleic acid is considered the origin of nervonic acid synthesis through fatty acid prolongation, where malonyl-CoA and acyl-CoA are initially concise by 3-ketoacyl-CoA synthase (KCS). To meet the high requirement of industrial production, the optimization of fermentation and bioreactors configurations are necessary tools to be carried out. This review article summarizes the research literature on advancements and recent trends about the production, synthesis and properties of nervonic acid.

Effects of Sex, Age, and Apolipoprotein E Genotype on Brain Ceramides and Sphingosine-1-Phosphate in Alzheimer's Disease and Control Mice

Apolipoprotein ε4 (APOE)4 is a strong risk factor for the development of Alzheimer’s disease (AD) and aberrant sphingolipid levels have been implicated in AD. We tested the hypothesis that the APOE4 genotype affects brain sphingolipid levels in AD. Seven ceramides and sphingosine-1-phosphate (S1P) were quantified by LC-MSMS in hippocampus, cortex, cerebellum, and plasma of <3 months and >5 months old human APOE3 and APOE4-targeted replacement mice with or without the familial AD (FAD) background of both sexes (145 animals). APOE4 mice had higher Cer(d18:1/24:0) levels in the cortex (1.7-fold, p = 0.002) than APOE3 mice. Mice with AD background showed higher levels of Cer(d18:1/24:1) in the cortex than mice without (1.4-fold, p = 0.003). S1P levels were higher in all three brain regions of older mice than of young mice (1.7-1.8-fold, all p ≤ 0.001). In female mice, S1P levels in hippocampus (r = −0.54 [−0.70, −0.35], p < 0.001) and in cortex correlated with those in plasma (r = −0.53 [−0.71, −0.32], p < 0.001). Ceramide levels were lower in the hippocampus (3.7–10.7-fold, all p < 0.001), but higher in the cortex (2.3–12.8-fold, p < 0.001) of female than male mice. In cerebellum and plasma, sex effects on individual ceramides depended on acyl chain length (9.5-fold lower to 11.5-fold higher, p ≤ 0.001). In conclusion, sex is a stronger determinant of brain ceramide levels in mice than APOE genotype, AD background, or age. Whether these differences impact AD neuropathology in men and women remains to be investigated.

Grape seed flour (GSF) extends longevity by improving multi-organ dysfunction and age-associated oxidative stress and inflammation in healthy rat

According to the free radical theory of aging, accumulation of reactive oxygen species (ROS) within mitochondria throughout lifespan leads to impairment of the main biological macromolecules as DNA, lipids and proteins, which might be at the basis of premature aging. One way to test experimentally such a hypothesis consists in intervention studies using antioxidant nutrients aimed at limiting or inhibiting ROS production that should be able to reduce the aging rate and disease pathogenesis. Grape seed flour (GSF) contains high level of phytochemicals among which bioactive polyphenols exhibit numerous biological properties and beneficial health effects as antioxidant, anti-inflammatory, anti-carcinogenic, multi-organ (heart, liver, kidney, and brain among others) protective. The present study aimed at testing the ability of high dosing GSF (4 g/kg bw) used as a nutritional supplement to slow down aging and prolong lifespan of Wistar rats when administered from early life (one month-old animals) till their natural death. Data clearly show that high dose GSF extends organism longevity and healthspan by improving multi-organ damages, systemic fuelling metabolism declines, and alleviated oxidative stress and inflammation in aging rats. Our data support the extending longevity effect of grape polyphenols especially when used as high dosing nutritional supplement or as natural medicine whose appropriate galenic form as solid lipid nanoformulation, is currently under investigation.

Fatty acids and beyond: Age and Alzheimer's disease related changes in lipids reveal the neuro-nutraceutical potential of lipids in cognition

Lipids are essential in maintaining brain function, and lipid profiles have been reported to be altered in aged and Alzheimer's disease (AD) brains as compared to healthy mature brains. Both age and AD share common metabolic hallmarks such as increased oxidative stress and perturbed metabolic function, and age remains the most strongly correlated risk factor for AD, a neurodegenerative disease. A major accompanying pathological symptom of these conditions is cognitive impairment, which is linked with changes in lipid metabolism. Thus, nutraceuticals that affect brain lipid metabolism or lipid levels as a whole have the potential to ameliorate cognitive decline. Lipid analyses and lipidomic studies reveal changes in specific lipid types with aging and AD, which can identify potential lipid-based nutraceuticals to restore the brain to a healthy lipid phenotype. The brain lipid profile can be influenced directly with dietary administration of lipids themselves, although because of synergistic effects of nutrients it may be more useful to consider a multi-component diet rather than single nutrient supplementation. Gut microbiota also serve as a source of beneficial lipids, and the value of treatments that manipulate the composition of gut microbiome should not be ignored. Lastly, instead of direct supplementation, compounds that affect pathways involved with lipid metabolism should also be considered as a way of manipulating lipid levels to improve cognition. In this review, we briefly discuss the role of lipids in the brain, the changing lipid profile in AD, current research on lipid-based nutraceuticals and their therapeutic potential to combat cognitive impairment.

A Review of Nervonic Acid Production in Plants: Prospects for the Genetic Engineering of High Nervonic Acid Cultivars Plants

Nervonic acid (NA) is a very-long-chain monounsaturated fatty acid that plays crucial roles in brain development and has attracted widespread research interest. The markets encouraged the development of a refined, NA-enriched plant oil as feedstocks for the needed further studies of NA biological functions to the end commercial application. Plant seed oils offer a renewable and environmentally friendly source of NA, but their industrial production is presently hindered by various factors. This review focuses on the NA biosynthesis and assembly, NA resources from plants, and the genetic engineering of NA biosynthesis in oil crops, discusses the factors that affect NA production in genetically engineered oil crops, and provides prospects for the application of NA and prospective trends in the engineering of NA. This review emphasizes the progress made toward various NA-related topics and explores the limitations and trends, thereby providing integrated and comprehensive insight into the nature of NA production mechanisms during genetic engineering. Furthermore, this report supports further work involving the manipulation of NA production through transgenic technologies and molecular breeding for the enhancement of crop nutritional quality or creation of plant biochemical factories to produce NA for use in nutraceutical, pharmaceutical, and chemical industries.

Nervonic acid amends motor disorder in a mouse model of Parkinson's disease

OBJECTIVES

Parkinson's disease (PD) is a kind of common neurodegenerative disease in the world. Previous studies have proved that nervonic acid (NA), extracted from Xanthoceras sorbifolia Bunge, has the potentials of neuroprotection. However, the effect of NA on the PD remained unknown. This study was designed to investigate the NA's potential function and relative mechanism on motor disorder.

METHODS

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was used for producing parkinsonism motor disorder on male C57BL/6 mice. Toxicity experiments and behavioral assay were performed to evaluate the effect of NA. Besides, the expression levels of tyrosine hydroxylase and α-synuclein, as well as striatal dopamine (DA), serotonin, and their metabolites were explored through immunoblotting and chromatography after NA treatment in vivo.

RESULTS

We found that NA could alleviate the MPTP-induced behavioral deficits dose-dependently. Moreover, NA has no toxic effects on the mouse liver and kidney. Of note, we found that NA significantly reduced the impact of MPTP impairment and striatal DA, serotonin, and metabolites were remained unaffected. In addition, tyrosine hydroxylase was upregulated while α-synuclein being downregulated and the oxidative stress was partially repressed evidenced by the upregulation of superoxide dismutase and glutathione activity after NA treatment.

CONCLUSION

Our findings unveil NA's potential for protecting motor system against motor disorder in the PD mouse model without any side effects, indicating NA as an alternative strategy for PD symptom remission.

Effect of mixed culture of yeast and microalgae on acetyl-CoA carboxylase and Glycerol-3-phosphate acyltransferase expression

In recent years, some studies have reported that co-culturing green algae and yeast improve lipid and biomass concentration. In this study, a co-culture of the oleaginous yeast Rhodotorula glutinis and the microalgae Chlorella vulgaris was consequently conducted with inoculation of microalga and yeast in growth and stationary phases, respectively. For the first time, the expression of two pivotal enzymes in fatty acids synthetic pathway, acetyl-CoA carboxylase and Glycerol-3-phosphate acyltransferase, was evaluated. To evaluate the synergistic impacts of the mixed culture on the enzymes expression, several co-culture models were designed, including the use of different ratio of microalgae to yeast or the use of residual cell-free medium of yeast; a positive impact on enzymes overexpression was shown in the case of the co-culture of the two microorganisms, and when the remaining cell-free medium of yeast was added to the microalgal culture. The results of in vitro co-culture demonstrated increased 6- and 5-fold of nervonic acid (C24:1) and behenic acid (C22:0) concentrations, respectively, in 2:1 microalgae to yeast co-culture as compared to the monoculture batches. Addition of yeast residual cell-free medium in the 2:1 ratio to the microalgal culture enhanced 9 and 6 times nervonic acid (C24:1) and behenic acid (C22:0) amounts, respectively.

Protective effect of (Xenical+GSF) against I/R-induced blood brain barrier disruption, ionic edema, lipid deregulation and neuroinflammation

Ischemic stroke is a leading cause of mortality worldwide that occurs following the reduction or interruption of blood brain supply, characterized by a cascade of early events as oxidative stress and ensuing neuro-inflammation, energy failure and the burst of intracellular Ca++ resulting in activation of phospholipases and large increase in FFA including arachidonic acid, ultimately leading to nervous cell death. Grape Seed Flour (GSF) is a complex polyphenolic mixture harboring antioxidant, anti-inflammatory and neuroprotective properties. Orlistat (Xenical ™,Xe) is a gastro-intestinal lipase inhibitor and an anti-obesity agent. In an earlier study we reported the higher efficiency in neuroprotection against HFD-induced brain lipotoxicity when combining the two drugs (GSF + Xe). As a result repurposing Xe as an adjunct to GSF therapy against stroke appeared relevant and worthy of investigation. I/R insult disrupted the blood brain barrier (BBB) as assessed by EB dye extravasation, increased water and Na⁺ within the brain. Ultrastructurally I/R altered the brain blood capillaries at the vicinity of hippocampus dentate gyrus area as assessed by transmission and scanning electron microscopy. I/R altered lipid metabolism as revealed by LDL/HDL ratio, lipase activity, and FFA profiles. Moreover, I/R induced neuro-inflammation as assessed by down-regulation of anti-inflammatory CD 56 and up-regulation of pro-inflammatory CD 68 antigen. Importantly almost all I/R-induced disturbances were retrieved partially upon Xe or GSF on their own, and optimally when combining the two drugs. Xe per se is protective against I/R injury and the best neuroprotection was obtained when associating low dosage Xe with high dosage GSF, enabling neuroprevention and cell survival within hippocampus dentate gyrus area as revealed by increased staining of Ki 67 proliferation biomarker.

Genome-Wide Screen of the Hippocampus in Aged Rats Identifies Mitochondria, Metabolism and Aging Processes Implicated in Sevoflurane Anesthesia

Previous studies have shown multiple mechanisms and pathophysiological changes after anesthesia, and genome-wide studies have been implemented in the studies of brain aging and neurodegenerative diseases. However, the genome-wide gene expression patterns and modulation networks after general anesthesia remains to be elucidated. Therefore, whole transcriptome microarray analysis was used to explore the coding gene expression patterns in the hippocampus of aged rats after sevoflurane anesthesia. Six hundred and thirty one upregulated and 183 downregulated genes were screened out, then 44 enriched terms of biological process, 16 of molecular function and 18 of the cellular components were identified by Gene Ontology (GO) and KEGG analysis. Among them, oxidative stress, metabolism, aging, and neurodegeneration were the most enriched biological processes and changed functions. Thus, involved genes of these processes were selected for qPCR verification and a good consistency was confirmed. The potential signaling pathways were further constructed including mitochondrion and oxidative stress-related Hifs-Prkcd-Akt-Nfe2l2-Sod1 signaling, multiple metabolism signaling (Scd2, Scap-Hmgcs2, Aldh18a1-Glul and Igf1r), as well as aging and neurodegeneration related signaling (Spidr-Ercc4-Cdkn1a-Pmaip1 and Map1lc3b). These results provide potential therapeutic gene targets for brain function modulation and memory formation process after inhaled anesthesia in the elderly, which could be valuable for preventing postoperative brain disorders and diseases, such as perioperative neurocognitive disorders (PND), from the genetic level in the future.

Elevated plasma ceramide levels in post-menopausal women: a cross-sectional study

Circulating ceramide levels are abnormally elevated in age-dependent pathologies such as cardiovascular diseases, obesity and Alzheimer's disease. Nevertheless, the potential impact of age on plasma ceramide levels has not yet been systematically examined. In the present study, we quantified a focused panel of plasma ceramides and dihydroceramides in a cohort of 164 subjects (84 women) 19 to 80 years of age. After adjusting for potential confounders, multivariable linear regression analysis revealed a positive association between age and ceramide (d18:1/24:0) (β (SE) = 5.67 (2.38); p = .0198) and ceramide (d18:1/24:1) (β (SE) = 2.88 (.61); p < .0001) in women, and between age and ceramide (d18:1/24:1) in men (β (SE) = 1.86 (.77); p = .0179). In women of all ages, but not men, plasma ceramide (d18:1/24:1) was negatively correlated with plasma estradiol (r = -0.294; p = .007). Finally, in vitro experiments in human cancer cells expressing estrogen receptors showed that incubation with estradiol (10 nM, 24 h) significantly decreased ceramide accumulation. Together, the results suggest that aging is associated with an increase in circulating ceramide levels, which in post-menopausal women is at least partially associated with lower estradiol levels.

Inhibition of nSMase2 Reduces the Transfer of Oligomeric α-Synuclein Irrespective of Hypoxia

Recently, extracellular vesicles (EVs), such as exosomes, have been proposed to play an influential role in the cell-to-cell spread of neurodegenerative diseases, including the intercellular transmission of α-synuclein (α-syn). However, the regulation of EV biogenesis and its relation to Parkinson’s disease (PD) is only partially understood. The generation of EVs through the ESCRT-independent pathway depends on the hydrolysis of sphingomyelin by neutral sphingomyelinase 2 (nSMase2) to produce ceramide, which causes the membrane of endosomal multivesicular bodies to bud inward. nSMase2 is sensitive to oxidative stress, a common process in PD brains; however, little is known about the role of sphingomyelin metabolism in the pathogenesis of PD. This is the first study to show that inhibiting nSMase2 decreases the transfer of oligomeric aggregates of α-syn between neuron-like cells. Furthermore, it reduced the accumulation and aggregation of high-molecular-weight α-syn. Hypoxia, as a model of oxidative stress, reduced the levels of nSMase2, but not its enzymatic activity, and significantly altered the lipid composition of cells without affecting EV abundance or the transfer of α-syn. These data show that altering sphingolipids can mitigate the spread of α-syn, even under hypoxic conditions, potentially suppressing PD progression.

A mini review of nervonic acid: Source, production, and biological functions

Nervonic acid (NA) has attracted considerable attention because of its close relationship with brain development. Sources of NA include oil crop seeds, oil-producing microalgae, and other microorganisms. Transgenic technology has also been applied to improve the sources and production of NA. NA can be separated and purified by urea adduction fractionation, molecular distillation, and crystallization. Studies on NA functionality involved treatments for demyelinating diseases and acquired immunodeficiency syndrome, as well as prediction of mortality due to cardiovascular diseases and chronic kidney disease. This mini review focuses on the sources, production, and biological functions of NA and provides prospective trends in the investigation of NA.

Age-Dependent Changes to Sphingolipid Balance in the Human Hippocampus are Gender-Specific and May Sensitize to Neurodegeneration

The greatest risk factor for developing Alzheimer's disease (AD) is aging. The major genetic risk factor for AD is the ɛ4 allele of the APOE gene, encoding the brain's major lipid transport protein, apolipoprotein E (ApoE). The research community is yet to decipher why the ApoE4 variant pre-disposes to AD, and how aging causes the disease. Studies have shown deregulated levels of sphingolipids, including decreased levels of the neuroprotective signaling lipid sphingosine 1-phosphate (S1P), and increased ceramide content, in brain tissue and serum of people with pre-clinical or very early AD. In this study we investigated whether sphingolipid levels are affected as a function of age or APOE genotype, in the hippocampus of neurologically normal subjects over the age of 65. Lipids were quantified in 80 postmortem tissue samples using liquid chromatography tandem mass spectrometry (LC-MS/MS). Sphingolipid levels were not significantly affected by the presence of one ɛ4 or ɛ2 allele. However, ceramide, sphingomyelin, and sulfatide content was very significantly correlated with age in the hippocampus of males. On the other hand, S1P, normalized to its non-phosphorylated precursor sphingosine, was inversely correlated with age in females. Our results therefore establish gender-specific differences in sphingolipid metabolism in the aging human brain. Ceramide is a pro-apoptotic lipid, and heavily implicated as a driver of insulin resistance in metabolic tissues. S1P is a neuroprotective lipid that supports glutamatergic neurotransmission. Increasing ceramide and decreasing S1P levels may contribute significantly to a pro-neurodegenerative phenotype in the aging brain.

The Cross-Talk Between Sphingolipids and Insulin-Like Growth Factor Signaling: Significance for Aging and Neurodegeneration

Bioactive sphingolipids: sphingosine, sphingosine-1-phosphate (S1P), ceramide, and ceramide-1-phosphate (C1P) are increasingly implicated in cell survival, proliferation, differentiation, and in multiple aspects of stress response in the nervous system. The opposite roles of closely related sphingolipid species in cell survival/death signaling is reflected in the concept of tightly controlled sphingolipid rheostat. Aging has a complex influence on sphingolipid metabolism, disturbing signaling pathways and the properties of lipid membranes. A metabolic signature of stress resistance-associated sphingolipids correlates with longevity in humans. Moreover, accumulating evidence suggests extensive links between sphingolipid signaling and the insulin-like growth factor I (IGF-I)-Akt-mTOR pathway (IIS), which is involved in the modulation of aging process and longevity. IIS integrates a wide array of metabolic signals, cross-talks with p53, nuclear factor κB (NF-κB), or reactive oxygen species (ROS) and influences gene expression to shape the cellular metabolic profile and stress resistance. The multiple connections between sphingolipids and IIS signaling suggest possible engagement of these compounds in the aging process itself, which creates a vulnerable background for the majority of neurodegenerative disorders.

Biosynthesis of nervonic acid and perspectives for its production by microalgae and other microorganisms

Nervonic acid (NA) is a major very long-chain monounsaturated fatty acid found in the white matter of mammalian brains, which plays a critical role in the treatment of psychotic disorders and neurological development. In the nature, NA has been synthesized by a handful plants, fungi, and microalgae. Although the metabolism of fatty acid has been studied for decades, the biosynthesis of NA has yet to be illustrated. Generally, the biosynthesis of NA is considered starting from oleic acid through fatty acid elongation, in which malonyl-CoA and long-chain acyl-CoA are firstly condensed by a rate-limiting enzyme 3-ketoacyl-CoA synthase (KCS). Heterologous expression of kcs gene from high NA producing species in plants and yeast has led to synthesis of NA. Nevertheless, it has also been reported that desaturases in a few plants can catalyze very long-chain saturated fatty acid into NA. This review highlights recent advances in the biosynthesis, the sources, and the biotechnological aspects of NA.