Brain uptake and utilization of fatty acids, lipids and lipoproteins: application to neurological disorders

Identification of lipid metabolism-related gene markers and construction of a diagnostic model for multiple sclerosis: An integrated analysis by bioinformatics and machine learning

BACKGROUND

Multiple sclerosis (MS) is an autoimmune inflammatory disorder that causes neurological disability. Dysregulated lipid metabolism contributes to the pathogenesis of MS. This study aimed to identify lipid metabolism-related gene markers and construct a diagnostic model for MS.

METHODS

Gene expression profiles for MS were obtained from the Gene Expression Omnibus database. Differentially expressed lipid metabolism-related genes (LMRGs) were identified and performed functional enrichment analysis. Least absolute shrinkage and selection operator (LASSO), random forest (RF), and protein-protein interaction (PPI) analysis were employed to screen hub genes. The predictive power of hub genes was evaluated using receiver operating characteristic (ROC) curves. We developed an artificial neural network (ANN) model and validated its performance in three test sets. Immune cell infiltration analysis, Gene set enrichment analysis, and ceRNA network construction were performed to explore the role of lipid metabolism in the pathogenesis of MS. Drugs prediction and molecular docking were utilized to identify potential therapeutic drugs.

RESULTS

We identified 40 differentially expressed LMRGs, with significant enrichment in Arachidonic acid metabolism, Steroid hormone biosynthesis, Fatty acid elongation, and Sphingolipid metabolism. AKR1C3, NFKB1, and ABCA1 were identified as gene markers for MS, and their expression was upregulated in the MS group. The areas under the ROC curve (AUCs) for AKR1C3, NFKB1, and ABCA1 in the training set were 0.779, 0.703, and 0.726, respectively. The ANN model exhibited good discriminative ability in both the training and test sets, achieving an AUC of 0.826 on the training set and AUC values of 0.822, 0.890, and 0.833 on the test sets. Gamma.delta.T.cell, Natural.killer.T.cell, Plasmacytoid.dendritic.cell, Regulatory.T.cell, and Type.1.T.helper.cell were highly expressed in the MS group. A ceRNA network showed a complex regulatory interplay involving hub genes. Luteolin, isoflavone, and thalidomide had good binding affinities to the hub genes.

CONCLUSION

Our study emphasized the crucial role of lipid metabolism in MS, identifing AKR1C3, NFKB1, and ABCA1 as gene markers. The ANN model exhibited good performance on both the training and testing sets. These findings offer valuable insights into the molecular mechanisms underlying MS, and establish a scientific foundation for future research.

ACSL3 is a promising therapeutic target for alleviating anxiety and depression in Alzheimer's disease

Alzheimer's disease (AD), the leading cause of dementia, affects over 55 million people worldwide and is often accompanied by depression and anxiety. Both significantly impact patients' quality of life and impose substantial societal and economic burdens on healthcare systems. Identifying the complex regulatory mechanisms that contribute to the psychological and emotional deficits in AD will provide promising therapeutic targets. Biosynthesis of omega-3 (ω3) and omega-6 fatty acids (ω6-FA) through long-chain acyl-CoA synthetases (ACSL) is crucial for cell function and survival. This is due to ω3/6-FA's imperative role in modulating the plasma membrane, energy production, and inflammation. While ACSL dysfunction is known to cause heart, liver, and kidney diseases, the role of ACSL in pathological conditions in the central nervous system (e.g., depression and anxiety) remains largely unexplored. The impact of ACSLs on AD-related depression and anxiety was investigated in a mouse model of Alzheimer's disease (3xTg-AD). ACSL3 levels were significantly reduced in the hippocampus of aged 3xTg-AD mice (via capillary-based immunoassay). This reduction in ACAL3 was closely associated with increased depression and anxiety-like behavior (via forced swim, tail suspension, elevated plus maze, and sucrose preference test). Upregulation of ACSL3 via adenovirus in aged 3xTg-AD mice led to increased protein levels of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor C (VEGF-C) (via brain histology, capillary-based immunoassay), resulting in alleviation of depression and anxiety symptoms. The present study highlights a novel neuroprotective role of ACSL3 in the brain. Targeting ACSL3 will offer an innovative approach for treating AD-related depression and anxiety.

Non-pharmacological therapeutic paradigms in stress-induced depression: from novel therapeutic perspective with focus on cell-based strategies

Major depressive disorder (MDD) is considered a psychiatric disorder and have a relationship with stressful events. Although the common therapeutic approaches against MDD are diverse, a large number of patients do not present an adequate response to antidepressant treatments. On the other hand, effective non-pharmacological treatments for MDD and their tolerability are addressed. Several affective treatments for MDD are used but non-pharmacological strategies for decreasing the common depression-related drugs side effects have been focused recently. However, the potential of extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs), microRNAs (miRNAs) as cell-based therapeutic paradigms, besides other non-pharmacological strategies including mitochondrial transfer, plasma, transcranial direct current stimulation (tDCS), transcranial magnetic stimulation (TMS), and exercise therapy needs to further study. This review explores the therapeutic potential of cell-based therapeutic non-pharmacological paradigms for MDD treatment. In addition, plasma therapy, mitotherapy, and exercise therapy in several in vitro and in vivo conditions in experimental disease models along with tDCS and TMS will be discussed as novel non-pharmacological promising therapeutic approaches.

Xingnao Jiutan tablets modulate gut microbiota and gut microbiota metabolism to alleviate cerebral ischemia/reperfusion injury

Introduction

Xingnao Jiutan tablets (XNJT), a compound Chinese medicine, have been applied to the treatment of the sequelae of cerebral thrombosis or cerebral hemorrhage, transient cerebral ischemia, and central retinal vein obstruction, etc., but the underlying mechanisms are not yet clear. This research focused on examining the impact of XNJT for cerebral ischemia/reperfusion (MCAO/R) injury, utilizing gut microbiota and metabolomic studies.

Methods

The primary components of XNJT were identified through the application of the HPLC technique. We established a MCAO/ R model in mice and conducted behavioral evaluations, cerebral blood flow measurements, and TTC staining. We used ELISA, high-throughput 16S rDNA gene sequencing, and metabolomics techniques to detect inflammatory factors, microbial populations, and metabolites, respectively. Finally, we performed Spearman correlation analysis to investigate the relationships among gut microbiota and metabolites, comprehensively exploring the mechanisms of XNJT to alleviate cerebral ischemia-reperfusion injury.

Results

We discovered that XNJT effectively enhanced neurological performance, alleviated cerebral infarction, diminished neuronal cell death, and increased cerebral blood flow. Moreover, XNJT downregulated the secretion of pro-inflammatory cytokines like TNF, IL-6, and IL-1b. Additionally, XNJT improved gut microbiota levels in MCAO/R mice, particularly Bacteroides, Firmicutes, Escherichia-Shigella, and Ligilactobacillus. Furthermore, XNJT primarily modulated differential metabolites in the gut through Glycerophospholipid, Linoleic acid, and Sphingolipid metabolism pathways. Spearman correlation analysis revealed significant associations among intestinal microbiota and various metabolites.

Discussion

In summary, our findings suggest that XNJT can improve cerebral ischemia/reperfusion injury outcomes, reduce inflammatory responses, and regulate gut microbiota and differential metabolites. It's possible that the potential mechanisms are connected to controlling gut microbiota and metabolism.

Neuronal Plasma Membranes as Supramolecular Assemblies for Biological Memory

Biological memory is the ability to develop, retain, and retrieve information over time. Currently, it is widely accepted that memories are stored in synapses (i.e., connections between brain cells throughout the brain) through a process known as synaptic plasticity, which leads to either long-term potentiation (LTP) or long-term depression (LTD). However, the strengthening (LTP) and weakening (LTD) of synapses involve post-translational modifications to neural networks requiring de novo gene expression, a lengthy and energetically expensive process. Recently, we observed that lipid bilayers in the absence of peptides/proteins are capable of LTP, not unlike what has been observed in mammals and birds. As such, this finding has prompted us to postulate that the lipid bilayer provides a good model for understanding the molecular basis of biological memory. In this article, we discuss the status, challenges, and opportunities of neuronal plasma membranes as structures for biological memory and learning, therapeutic targets for various brain disorders, and platforms for neural network developments.

Elevation of ganglioside degradation pathway drives GM2 and GM3 within amyloid plaques in a transgenic mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease that accounts for two-thirds of all dementia cases, and age is the strongest risk factor. In addition to the amyloid hypothesis, lipid dysregulation is now recognized as a core component of AD pathology. Gangliosides are a class of membrane lipids of the glycosphingolipid family and are enriched in the central nervous system (CNS). Ganglioside dysregulation has been implicated in various neurodegenerative diseases, including AD, but the spatial distribution of ganglioside dysregulation with respect to amyloid-beta (Aβ) deposition is not well understood. To address this gap, matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) was employed to investigate the age-dependent expression profiles of the A-series ganglioside species GD1a, GM1, GM2, and GM3 in the APP/PS1 transgenic mouse model of AD in which age-dependent amyloid-beta (Aβ) plaques develop. This study utilized a dual-resolution approach in combination with whole-brain imaging for comprehensive detection of ganglioside expression across neuroanatomical regions via high-resolution imaging of the cerebral cortex and hippocampus to investigate plaque-associated ganglioside alterations. The results revealed age-dependent changes in the complex gangliosides GM1 and GD1a across white and gray matter regions in both wildtype and APP/PS1 mice. Significantly greater levels of simple gangliosides GM2 and GM3 were observed in the cortex and dentate gyrus of the hippocampus in transgenic mice at 12 and 18 m than in age-matched controls. The accumulation of GM3 colocalized with Aβ plaques in aged APP/PS1 mice and correlated with Hexa gene expression, suggesting that ganglioside degradation is a mechanism for the accumulation of GM3. This work is the first to demonstrate that age-related ganglioside dysregulation is spatiotemporally associated with Aβ plaques using sophisticated MSI and reveals novel mechanistic insights into lipid regulation in AD.

Lipidome disruption in Alzheimer's disease brain: detection, pathological mechanisms, and therapeutic implications

Alzheimer's disease (AD) is among the most devastating neurodegenerative disorders with limited treatment options. Emerging evidence points to the involvement of lipid dysregulation in the development of AD. Nevertheless, the precise lipidomic landscape and the mechanistic roles of lipids in disease pathology remain poorly understood. This review aims to highlight the significance of lipidomics and lipid-targeting approaches in the diagnosis and treatment of AD. We summarized the connection between lipid dysregulation in the human brain and AD at both genetic and lipid species levels. We briefly introduced lipidomics technologies and discussed potential challenges and areas of future advancements in the lipidomics field for AD research. To elucidate the central role of lipids in converging multiple pathological aspects of AD, we reviewed the current knowledge on the interplay between lipids and major AD features, including amyloid beta, tau, and neuroinflammation. Finally, we assessed the progresses and obstacles in lipid-based therapeutics and proposed potential strategies for leveraging lipidomics in the treatment of AD.

Creation of a novel zebrafish model with low DHA status to study the role of maternal nutrition during neurodevelopment

Docosahexaenoic acid (DHA), a dietary omega-3 fatty acid, is a major building block of brain cell membranes. Offspring rely on maternal DHA transfer to meet their neurodevelopmental needs, but DHA sources are lacking in the American diet. Low DHA status is linked to altered immune responses, white matter defects, impaired vision, and an increased risk of psychiatric disorders during development. However, the underlying cellular mechanisms involved are largely unknown, and advancements in the field have been limited by the existing tools and animal models. Zebrafish are an excellent model for studying neurodevelopmental mechanisms. Embryos undergo rapid external development and are optically transparent, enabling direct observation of individual cells and dynamic cell-cell interactions in a way that is not possible in rodents. Here, we create a novel DHA-deficient zebrafish model by 1) disrupting elovl2, a key gene in the DHA biosynthesis pathway, via CRISPR/Cas9 genome editing, and 2) feeding mothers a DHA-deficient diet. We show that low DHA status during development is associated with an abnormal eye phenotype and demonstrate that even morphologically normal siblings exhibit dysregulated vision and stress response gene pathways. Future work using our zebrafish model could reveal the cellular and molecular mechanisms by which low DHA status leads to neurodevelopmental abnormalities, and provide insight into maternal nutritional strategies that optimize infant brain health.

The Role of Cardiolipin in Brain Bioenergetics, Neuroinflammation, and Neurodegeneration

Cardiolipin (CL) is an essential phospholipid that supports the functions of mitochondrial membrane transporters and oxidative phosphorylation complexes. Due to the high level of fatty acyl chain unsaturation, CL is prone to peroxidation during aging, neurodegenerative disease, stroke, and traumatic brain or spinal cord injury. Therefore, effective therapies that stabilize and preserve CL levels or enhance healthy CL fatty acyl chain remodeling are needed. In the last few years, great strides have been made in determining the mechanisms through which precursors for CL biosynthesis, such as phosphatidic acid (PA), are transferred from the ER to the outer mitochondrial membrane (OMM) and then to the inner mitochondrial membrane (IMM) where CL biosynthesis takes place. Many neurodegenerative disorders show dysfunctional mitochondrial ER contact sites that may perturb PA transport and CL biosynthesis. However, little is currently known on how neuronal mitochondria regulate the synthesis, remodeling, and degradation of CL. This review will focus on recent developments on the role of CL in neurological disorders. Importantly, due to CL species in the brain being more unsaturated and diverse than in other tissues, this review will also identify areas where more research is needed to determine a complete picture of brain and spinal cord CL function so that effective therapeutics can be developed to restore the rates of CL synthesis and remodeling in neurological disorders.

Differential Lipid Signatures of Lumbar and Cisternal Cerebrospinal Fluid

BACKGROUND

The molecular composition of cerebrospinal fluid (CSF) is often used as a key indicator of biochemical alterations within distinct brain and spinal cord fluid compartments. The CSF protein content in lumbar CSF samples is widely employed as a biomarker matrix for diagnosing brain-related pathological conditions. CSF lipid profiles may serve as promising complementary diagnostics, but it remains unresolved if the lipid distribution is consistent along the neuroaxis.

METHODS

The lipid composition was determined with liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) in cisternal CSF obtained from healthy subjects undergoing preventive surgery of an unruptured aneurism (n = 11) and lumbar CSF obtained from individuals referred for the clinical evaluation of cognitive dysfunction but subsequently cleared and deemed healthy (n = 19).

RESULTS

We reveal discernible variations in lipid composition along the neuroaxis, with a higher overall lipid concentration in cisternal CSF, although with different relative distributions of the various lipid classes in the two compartments. The cisternal CSF contained elevated levels of most lipid classes, e.g., sphingomyelins, lysophosphatidylcholines, plasmenylphosphatidylcholines, phosphatidic acids, and triacylglycerols, whereas a few select lipids from the classes of fatty acids, phosphatidylcholines, amides and plasmenylphosphatidylethanolamines were, oppositely, elevated in the lumbar CSF pool.

CONCLUSIONS

The distinct lipid distribution along the neuroaxis illustrates that the molecular constituents in these two CSF compartments are not uniform. These findings emphasize the necessity of establishing a lumbar lipid index for the accurate interpretation of the cranial CSF lipid profile.

Benzopyrene represses mitochondrial fission factors and PINK1/Parkin-mediated mitophagy in primary astrocytes

Mitochondria are essential for various physiological functions in astrocytes in the brain, such as maintaining ion and pH homeostasis, regulating neurotransmission, and modulating neuroinflammation. Mitophagy, a form of autophagy specific to mitochondria, is essential for ensuring mitochondrial quality and function. Benzo[a]pyrene (BaP) accumulates in the brain, and exposure to it is recognized as an environmental risk factor for neurodegenerative diseases. However, while the toxic mechanisms of BaP have been investigated in neurons, their effects on astrocytes-the most prevalent glial cells in the brain-are not clearly understood. Therefore, this study aims to investigate the toxic effects of exposure to BaP on mitochondria in primary astrocytes. Fluorescent probes and genetically encoded indicators were utilized to visualize mitochondrial morphology and physiology, and regulatory factors involved in mitochondrial morphology and mitophagy were assessed. Additionally, the mitochondrial respiration rate was measured in BaP-exposed astrocytes. BaP exposure resulted in mitochondrial enlargement owing to the suppression of mitochondrial fission factors. Furthermore, BaP-exposed astrocytes demonstrated reduced mitophagy and exhibited aberrant mitochondrial function and physiology, such as altered mitochondrial respiration rates, increased mitochondrial superoxide, disrupted mitochondrial membrane potential, and dysregulated mitochondrial Ca2+. These findings offer insights into the underlying toxic mechanisms of BaP exposure in neurodegenerative diseases by inducing aberrant mitophagy and mitochondrial dysfunction in astrocytes.

Chemical characterization, neuroprotective effect, and in-silico evaluation of the petroleum ether extract of three palm tree species against glutamate-induced excitotoxicity in rats

The burden of neurological disorders is growing substantially with limited therapeutic options, urging the consideration and assessment of alternative strategies. In this regard, we aimed to elucidate the phytochemical profile of the petroleum ether extract (PEE) of three palm tree species: Aiphanes eggersii Burret, Carpoxylon macrospermum H. Wendl. & Drude, and Jubaeopsis caffra Becc. (Family Arecaceae), and to evaluate their neuroprotective effect in monosodium glutamate (MSG)-induced excitotoxicity model for the first time. We identified a total of 48, 18, and 45 compounds in A. eggersii, C. macrospermum, and J. caffra, constituting 79.41 %, 60.45 %, and 76.35 % of the total detected compounds, respectively. A. eggersii extract was rich in the methyl esters of fatty acids (65.08 %) especially methyl dodecanoate (17.72 %). C. macrospermum was exclusively prolific by the triterpene 3β-methoxy-d:c-friedo-b':a'-neogammacer-9(11)-ene (40.36 %), while J. caffra was noticeable by hydrocarbons (30.14 %) and lupeol derivatives (19.79 %). The biochemical and histopathological analysis showed that the tested extracts significantly reduced the oxidative stress, especially at the highest tested dose (1000 mg/kg). The extracts also reduced the activity of induced nitric oxide synthetase, Ca+2 level, and NR2B subunit expression and attenuated apoptosis and DNA damage. The docking results show that most active natural compounds bind to SOD-1 and NR2B-NMDARs, verifying the credibility of the biological findings. To sum up, the PEE of the three investigated palm tree species possessed a unique blend of lipophilic bioactive constituents that exert promising neuroprotective potential against MSG-induced excitoneurotoxicity. However, further preclinical investigation and pharmaceutical formulation are needed.

Olive Oil Industry By-Products as a Novel Source of Biophenols with a Promising Role in Alzheimer Disease Prevention

This review explores the potential health benefits and applications of phenolic secoiridoids derived from olive oil by-products in the prevention of Alzheimer's disease (AD). As reviewed herein, polyphenols, such as epigallocatechin-3-gallate, epicatechin, and resveratrol, show in vitro and in vivo antioxidant, anti-inflammatory, and neuroprotective properties, and are particularly relevant in the context of AD, a leading cause of dementia globally. The olive oil industry, particularly in the Mediterranean region, produces significant amounts of waste, including leaves, pomace, and wastewater, which pose environmental challenges but also offer an untapped source of bioactive compounds. Despite promising in vitro and in vivo studies indicating that olive-derived polyphenols, such as oleuropein and hydroxytyrosol, may mitigate AD pathology, human clinical trials remain limited. The variability in extraction methods and the complex nature of AD further complicate research. Future studies should focus on standardizing the protocols and conducting robust clinical trials to fully assess the therapeutic potential of these compounds. This approach not only supports the development of new treatments for AD but also promotes environmental sustainability by valorizing olive oil industry waste.

Proposed Physiological Mechanisms Underlying the Association between Adverse Childhood Experiences and Mental Health Conditions: A Narrative Review

Adverse childhood experiences (ACEs; e.g., physical abuse) can impact lifelong mental health both directly and intergenerationally, with effects transmitted from the parent to the child. Several physiological mechanisms have been proposed to explain the impacts of ACEs on mental health. The purpose of this narrative review was to synthesize and critique the peer-reviewed literature on physiological mechanisms proposed to underlie the impacts of ACEs on mental health, specifically: (1) hypothalamic-pituitary-adrenal axis functioning, (2) inflammation, (3) genetic inheritance and differential susceptibility, (4) epigenetics, (5) brain structure and function, (6) oxidative stress, and (7) metabolic profiles. We searched Google Scholar using variations of the terms "adverse childhood experiences", "mechanisms", and "mental health" to locate relevant peer-reviewed literature. We also mined citations of the identified literature to find additional important sources. The role of inflammation in the etiology of mental health conditions among those exposed to ACEs appeared promising, followed by hypothalamic-pituitary-adrenal axis functioning, brain structure and function, genetics, epigenetics, metabolism, and lastly, oxidative stress. Replication studies that examine the associations among ACEs, genetic inheritance and differential susceptibility, epigenetics, oxidative stress, and metabolism are required to better define links with mental health.

GEGA (Gallus Enriched Gene Annotation): an online tool providing genomics and functional information across 47 tissues for a chicken gene-enriched atlas gathering Ensembl and Refseq genome annotations

GEGA is a user-friendly tool designed to navigate through various genomic and functional information related to an enriched gene atlas in chicken that integrates the gene catalogues from the two reference databases, NCBI-RefSeq and EMBL-Ensembl/GENCODE, along with four additional rich resources such as FAANG and NONCODE. Using the latest GRCg7b genome assembly, GEGA encompasses a total of 78 323 genes, including 24 102 protein-coding genes (PCGs) and 44 428 long non-coding RNAs (lncRNAs), significantly increasing the number of genes provided by each resource independently. However, GEGA is more than just a gene database. It offers a range of features that allow us to go deeper into the functional aspects of these genes. Users can explore gene expression and co-expression profiles across 47 tissues from 36 datasets and 1400 samples, discover tissue-specific variations and their expression as a function of sex or age and extract orthologous genes or their genomic configuration relative to the closest gene. For the communities interested in a specific gene, a list of genes or a quantitative trait locus region in chicken, GEGA's user-friendly interface facilitates efficient gene analysis, easy downloading of results and a multitude of graphical representations, from genomic information to detailed visualization of expression levels.

Lipids and α-Synuclein: adding further variables to the equation

Aggregation of alpha-Synuclein (αSyn) has been connected to several neurodegenerative diseases, such as Parkinson's disease (PD), dementia with Lewy Bodies (DLB), and multiple system atrophy (MSA), that are collected under the umbrella term synucleinopathies. The membrane binding abilities of αSyn to negatively charged phospholipids have been well described and are connected to putative physiological functions of αSyn. Consequently, αSyn-related neurodegeneration has been increasingly connected to changes in lipid metabolism and membrane lipid composition. Indeed, αSyn aggregation has been shown to be triggered by the presence of membranes in vitro, and some genetic risk factors for PD and DLB are associated with genes coding for proteins directly involved in lipid metabolism. At the same time, αSyn aggregation itself can cause alterations of cellular lipid composition and brain samples of patients also show altered lipid compositions. Thus, it is likely that there is a reciprocal influence between cellular lipid composition and αSyn aggregation, which can be further affected by environmental or genetic factors and ageing. Little is known about lipid changes during physiological ageing and regional differences of the lipid composition of the aged brain. In this review, we aim to summarise our current understanding of lipid changes in connection to αSyn and discuss open questions that need to be answered to further our knowledge of αSyn related neurodegeneration.

Creation of a novel zebrafish model with low DHA status to study the role of maternal nutrition during neurodevelopment

Docosahexaenoic acid (DHA), a dietary omega-3 fatty acid, is a major building block of brain cell membranes. Offspring rely on maternal DHA transfer to meet their neurodevelopmental needs, but DHA sources are lacking in the American diet. Low DHA status is linked to altered immune responses, white matter defects, impaired vision, and an increased risk of psychiatric disorders during development. However, the underlying cellular mechanisms involved are largely unknown, and advancements in the field have been limited by the existing tools and animal models. Zebrafish are an excellent model for studying neurodevelopmental mechanisms. Embryos undergo rapid external development and are optically transparent, enabling direct observation of individual cells and dynamic cell-cell interactions in a way that is not possible in rodents. Here, we create a novel DHA-deficient zebrafish model by 1) disrupting elovl2, a key gene in the DHA biosynthesis pathway, via CRISPR-Cas9 genome editing, and 2) feeding mothers a DHA-deficient diet. We show that low DHA status during development is associated with a small eye morphological phenotype and demonstrate that even the morphologically normal siblings exhibit dysregulated gene pathways related to vision and stress response. Future work using our zebrafish model could reveal the cellular and molecular mechanisms by which low DHA status leads to neurodevelopmental abnormalities and provide insight into maternal nutritional strategies that optimize infant brain health.

The protective effect of biotin supplementation and swimming training on cognitive impairment and mental symptoms in a rat model of Alzheimer's disease: A behavioral, biochemical, and histological study

Vitamin B (Vit B) plays a regulatory role in cognitive memory and learning. We examined the biochemical and behavioral effects of biotin supplementation (BS) and swimming training (ST) on Alzheimer's disease (AD), the most common type of dementia, in male rats. Sixty rats were randomly assigned to six groups: control, sham (receiving phosphate-buffered saline), AD (receiving a single injection of Aβ into the lateral ventricle), ST (for 28 days and before Aβ injection), and BS (receiving BS through oral gavage for 28 days before Aβ injection). The treatments were continued until the end of the behavioral tests. Learning and memory functions were investigated through the Morris water maze (MWM) and depression and anxiety-like behaviors were tested by elevated plus-maze (EPM) and forced swimming tests. In addition, oxidative stress biomarkers, such as total thiol groups (TTG) and malondialdehyde (MDA) in serum were assessed and histological studies were performed using brain tissues. In the AD group, Aβ increased the distance traveled and escape latency in the MWM, but co-administration of BS and ST attenuated the results of the MWM, EPM, and FST tests. Furthermore, BS decreased the litigious biochemical effects of Aβ by enhancing the levels of TTG, in addition to reducing serum MDA levels. The use of BS as a potent antioxidant improved Aβ-induced memory impairment. It attenuated oxidative stress biomarkers in the brain (number of Aβ plaques) and serum of AD rats. We provide evidence for the use of BS in neurodegenerative disorders, such as AD, to elucidate the possible mechanisms.

Aging, sex, metabolic and life experience factors: Contributions to neuro-inflammaging in Alzheimer's disease research

Alzheimer's disease (AD) is prevalent around the world, yet our understanding of the disease is still very limited. Recent work suggests that the cornerstone of AD may include the inflammation that accompanies it. Failure of a normal pro-inflammatory immune response to resolve may lead to persistent central inflammation that contributes to unsuccessful clearance of amyloid-beta plaques as they form, neuronal death, and ultimately cognitive decline. Individual metabolic, and dietary (lipid) profiles can differentially regulate this inflammatory process with aging, obesity, poor diet, early life stress and other inflammatory factors contributing to a greater risk of developing AD. Here, we integrate evidence for the interface between these factors, and how they contribute to a pro-inflammatory brain milieu. In particular, we discuss the importance of appropriate polyunsaturated fatty acids (PUFA) in the diet for the metabolism of specialised pro-resolving mediators (SPMs); raising the possibility for dietary strategies to improve AD outlook.

Mass spectrometry imaging of N-linked glycans: Fundamentals and recent advances

With implications in several medical conditions, N-linked glycosylation is one of the most important posttranslation modifications present in all living organisms. Due to their nontemplate synthesis, glycan structures are extraordinarily complex and require multiple analytical techniques for complete structural elucidation. Mass spectrometry is the most common way to investigate N-linked glycans; however, with techniques such as liquid-chromatography mass spectrometry, there is complete loss of spatial information. Mass spectrometry imaging is a transformative analytical technique that can visualize the spatial distribution of ions within a biological sample and has been shown to be a powerful tool to investigate N-linked glycosylation. This review covers the fundamentals of mass spectrometry imaging and N-linked glycosylation and highlights important findings of recent key studies aimed at expanding and improving the glycomics imaging field.

In the Brain, It Is Not All about Sugar

The maintenance of energetic homeostasis relies on a tight balance between glycolysis and mitochondrial oxidative phosphorylation. The case of the brain is a peculiar one, as although entailing a constant demand for energy, it is believed to rely mostly on glucose, particularly at the level of neurons. Nonetheless, this has been challenged by studies that show that alternatives such as lactate, ketone bodies, and glutamate can be used as fuels to sustain neuronal activity. The importance of fatty acid (FA) metabolism to this extent is still unclear, albeit sustaining a significant energetic output when compared to glucose. While several authors postulate a possible role of FA for the energetic homeostasis of the brain, several others point out the intrinsic features of this pathway that make its contribution difficult to explain in the context of neuronal bioenergetics. Moreover, fueling preference at the synapse level is yet to be uncovered. In this review, we discuss in detail the arguments for and against the brain usage of FA. Furthermore, we postulate that the importance of this fuel may be greater at the synapse, where local mitochondria possess a set of features that enable a more effective usage of this fuel source.

Multiomics analysis to explore blood metabolite biomarkers in an Alzheimer's Disease Neuroimaging Initiative cohort

Alzheimer's disease (AD) is a neurodegenerative disease that commonly causes dementia. Identifying biomarkers for the early detection of AD is an emerging need, as brain dysfunction begins two decades before the onset of clinical symptoms. To this end, we reanalyzed untargeted metabolomic mass spectrometry data from 905 patients enrolled in the AD Neuroimaging Initiative (ADNI) cohort using MS-DIAL, with 1,304,633 spectra of 39,108 unique biomolecules. Metabolic profiles of 93 hydrophilic metabolites were determined. Additionally, we integrated targeted lipidomic data (4873 samples from 1524 patients) to explore candidate biomarkers for predicting progressive mild cognitive impairment (pMCI) in patients diagnosed with AD within two years using the baseline metabolome. Patients with lower ergothioneine levels had a 12% higher rate of AD progression with the significance of P = 0.012 (Wald test). Furthermore, an increase in ganglioside (GM3) and decrease in plasmalogen lipids, many of which are associated with apolipoprotein E polymorphism, were confirmed in AD patients, and the higher levels of lysophosphatidylcholine (18:1) and GM3 d18:1/20:0 showed 19% and 17% higher rates of AD progression, respectively (Wald test: P = 3.9 × 10-8 and 4.3 × 10-7). Palmitoleamide, oleamide, diacylglycerols, and ether lipids were also identified as significantly altered metabolites at baseline in patients with pMCI. The integrated analysis of metabolites and genomics data showed that combining information on metabolites and genotypes enhances the predictive performance of AD progression, suggesting that metabolomics is essential to complement genomic data. In conclusion, the reanalysis of multiomics data provides new insights to detect early development of AD pathology and to partially understand metabolic changes in age-related onset of AD.

Integrative brain omics approach reveals key role for sn-1 lysophosphatidylethanolamine in Alzheimer's dementia

The biology of individual lipid species and their relevance in Alzheimer's disease (AD) remains incompletely understood. We utilized non-targeted mass spectrometry to examine brain lipids variations across 316 post-mortem brains from participants in the Religious Orders Study (ROS) or Rush Memory and Aging Project (MAP) cohorts classified as either control, asymptomatic AD (AAD), or symptomatic AD (SAD) and integrated the lipidomics data with untargeted proteomic characterization on the same individuals. Lipid enrichment analysis and analysis of variance identified significantly lower abundance of lysophosphatidylethanolamine (LPE) and lysophosphatidylcholine (LPC) species in SAD than controls or AAD. Lipid-protein co-expression network analyses revealed that lipid modules consisting of LPE and LPC exhibited a significant association to protein modules associated with MAPK/metabolism, post-synaptic density, and Cell-ECM interaction pathways and were associated with better antemortem cognition and with neuropathological changes seen in AD. Particularly, LPE 22:6 [sn-1] levels are significantly decreased across AD cases (SAD) and show the most influence on protein changes compared to other lysophospholipid species. LPE 22:6 may be a lipid signature for AD and could be leveraged as potential therapeutic or dietary targets for AD.

Cord blood lipid correlation network profiles are associated with subsequent attention-deficit/hyperactivity disorder and autism spectrum disorder symptoms at 2 years: a prospective birth cohort study

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are neurodevelopmental conditions with early life origins. Alterations in blood lipids have been linked to ADHD and ASD; however, prospective early life data are limited. This study examined (i) associations between the cord blood lipidome and ADHD/ASD symptoms at 2 years of age, (ii) associations between prenatal and perinatal predictors of ADHD/ASD symptoms and cord blood lipidome, and (iii) mediation by the cord blood lipidome.

METHODS

From the Barwon Infant Study cohort (1074 mother-child pairs, 52.3% male children), child circulating lipid levels at birth were analysed using ultra-high-performance liquid chromatography-tandem mass spectrometry. These were clustered into lipid network modules via Weighted Gene Correlation Network Analysis. Associations between lipid modules and ADHD/ASD symptoms at 2 years, assessed with the Child Behavior Checklist, were explored via linear regression analyses. Mediation analysis identified indirect effects of prenatal and perinatal risk factors on ADHD/ASD symptoms through lipid modules.

FINDINGS

The acylcarnitine lipid module is associated with both ADHD and ASD symptoms at 2 years of age. Risk factors of these outcomes such as low income, Apgar score, and maternal inflammation were partly mediated by higher birth acylcarnitine levels. Other cord blood lipid profiles were also associated with ADHD and ASD symptoms.

INTERPRETATION

This study highlights that elevated cord blood birth acylcarnitine levels, either directly or as a possible marker of disrupted cell energy metabolism, are on the causal pathway of prenatal and perinatal risk factors for ADHD and ASD symptoms in early life.

FUNDING

The foundational work and infrastructure for the BIS was sponsored by the Murdoch Children's Research Institute, Deakin University, and Barwon Health. Subsequent funding was secured from the Minderoo Foundation, the European Union's Horizon 2020 research and innovation programme (ENDpoiNTs: No 825759), National Health and Medical Research Council of Australia (NHMRC) and Agency for Science, Technology and Research Singapore [APP1149047], The William and Vera Ellen Houston Memorial Trust Fund (via HOMER Hack), The Shepherd Foundation, The Jack Brockhoff Foundation, the Scobie & Claire McKinnon Trust, the Shane O'Brien Memorial Asthma Foundation, the Our Women Our Children's Fund Raising Committee Barwon Health, the Rotary Club of Geelong, the Ilhan Food Allergy Foundation, Geelong Medical and Hospital Benefits Association, Vanguard Investments Australia Ltd, the Percy Baxter Charitable Trust, and Perpetual Trustees.

Choline metabolism in regulating inflammatory bowel disease-linked anxiety disorders: A multi-omics exploration of the gut-brain axis

Anxiety and depression caused by inflammatory bowel disease (IBD) negatively affect the mental health of patients. Emerging studies have demonstrated that the gut-brain axis (GBA) mediates IBD-induced mood disorders, but the underlying mechanisms of these findings remain unknown. Therefore, it's vital to conduct comprehensive research on the GBA in IBD. Multi-omics studies can provide an understanding of the pathological mechanisms of the GBA in the development of IBD, helping to uncover the mechanisms underlying the onset and progression of the disease. Thus, we analyzed the prefrontal cortex (PFC) of Dextran Sulfate Sodium Salt (DSS)-induced IBD mice using transcriptomics and metabolomics. We observed increased mRNA related to acetylcholine synthesis and secretion, along with decreased phosphatidylcholine (PC) levels in the PFC of DSS group compared to the control group. Fecal metagenomics also revealed abnormalities in the microbiome and lipid metabolism in the DSS group. Since both acetylcholine and PC are choline metabolites, we posited that the DSS group may experience choline deficiency and choline metabolism disorders. Subsequently, when we supplemented CDP-choline, IBD mice exhibited improvements, including decreased anxiety-like behaviors, reduced PC degradation, and increased acetylcholine synthesis in the PFC. In addition, administration of CDP-choline can restore imbalances in the gut microbiome and disruptions in lipid metabolism caused by DSS treatment. This study provides compelling evidence to suggest that choline metabolism plays a crucial role in the development and treatment of mood disorders in IBD. Choline and its metabolites appear to have a significant role in maintaining the stability of the GBA.

Comparing Brain and Blood Lipidome Changes following Single and Repetitive Mild Traumatic Brain Injury in Rats

Traumatic brain injury (TBI) is a major health concern in the United States and globally, contributing to disability and long-term neurological problems. Lipid dysregulation after TBI is underexplored, and a better understanding of lipid turnover and degradation could point to novel biomarker candidates and therapeutic targets. Here, we investigated overlapping lipidome changes in the brain and blood using a data-driven discovery approach to understand lipid alterations in the brain and serum compartments acutely following mild TBI (mTBI) and the potential efflux of brain lipids to peripheral blood. The cortices and sera from male and female Sprague-Dawley rats were analyzed via ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) in both positive and negative ion modes following single and repetitive closed head impacts. The overlapping lipids in the data sets were identified with an in-house data dictionary for investigating lipid class changes. MS-based lipid profiling revealed overall increased changes in the serum compartment, while the brain lipids primarily showed decreased changes. Interestingly, there were prominent alterations in the sphingolipid class in the brain and blood compartments after single and repetitive injury, which may suggest efflux of brain sphingolipids into the blood after TBI. Genetic algorithms were used for predictive panel selection to classify injured and control samples with high sensitivity and specificity. These overlapping lipid panels primarily mapped to the glycerophospholipid metabolism pathway with Benjamini-Hochberg adjusted q-values less than 0.05. Collectively, these results detail overlapping lipidome changes following mTBI in the brain and blood compartments, increasing our understanding of TBI-related lipid dysregulation while identifying novel biomarker candidates.

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%).

Large-Scale Population-Based Studies of Blood Metabolome and Brain Health

Metabolomics technologies enable the quantification of multiple metabolomic measures simultaneously, which provides novel insights into molecular aspects of human health and disease. In large-scale, population-based studies, blood is often the preferred biospecimen. Circulating metabolome may relate to brain health either by affecting or reflecting brain metabolism. Peripheral metabolites may act at or cross the blood-brain barrier and, subsequently, influence brain metabolism, or they may reflect brain metabolism if similar pathways are engaged. Peripheral metabolites may also include those penetrating the circulation from the brain, indicating, for example, brain damage. Most brain health-related metabolomics studies have been conducted in the context of neurodegenerative disorders and cognition, but some studies have also focused on neuroimaging markers of these disorders. Moreover, several metabolomics studies of neurodevelopmental disorders have been performed. Here, we provide a brief background on the types of blood metabolites commonly assessed, and we review the literature describing the relationships between human blood metabolome (n > 50 metabolites) and brain health reported in large-scale studies (n > 500 individuals).

Quantitative and Qualitative Analysis of Neurotransmitter and Neurosteroid Production in Cerebral Organoids during Differentiation

In the human brain, neurophysiological activity is modulated by the movement of neurotransmitters and neurosteroids. To date, the similarity between cerebral organoids and actual human brains has been evaluated using comprehensive multiomics approaches. However, a systematic analysis of both neurotransmitters and neurosteroids from cerebral organoids has not yet been reported. Here, we performed quantitative and qualitative assessments of neurotransmitters and neurosteroids over the course of cerebral organoid differentiation. Our multiomics approaches revealed that the expression levels of neurotransmitter-related proteins and RNA, including neurosteroids, increase as cerebral organoids mature. We also found that the electrophysiological activity of human cerebral organoids increases in tandem with the expression levels of both neurotransmitters and neurosteroids. Our study demonstrates that the expression levels of neurotransmitters and neurosteroids can serve as key factors in evaluating the maturity and functionality of human cerebral organoids.

Lipids in major depressive disorder: new kids on the block or old friends revisited?

Major depressive disorder (MDD) is a psychiatric mood disorder that results in substantial functional impairment and is characterized by symptoms such as depressed mood, diminished interest, impaired cognitive function, and vegetative symptoms such as disturbed sleep. Although the exact etiology of MDD is unclear, several underlying mechanisms (disturbances in immune response and/or stress response) have been associated with its development, with no single mechanism able to account for all aspects of the disorder. Currently, about 1 in 3 patients are resistant to current antidepressant therapies. Providing an alternative perspective on MDD could therefore pave the way for new, unexplored diagnostic and therapeutic solutions. The central nervous system harbors an enormous pool of lipids and lipid intermediates that have been linked to a plethora of its physiological functions. The aim of this review is therefore to provide an overview of the implications of lipids in MDD and highlight certain MDD-related underlying mechanisms that involve lipids and/or their intermediates. Furthermore, we will also focus on the bidirectional relationship between MDD and the lipid-related disorders obesity and type 2 diabetes.

Apolipoprotein E in lipid metabolism and neurodegenerative disease

Dysregulation of lipid metabolism has emerged as a central component of many neurodegenerative diseases. Variants of the lipid transport protein, apolipoprotein E (APOE), modulate risk and resilience in several neurodegenerative diseases including late-onset Alzheimer's disease (LOAD). Allelic variants of the gene, APOE, alter the lipid metabolism of cells and tissues and have been broadly associated with several other cellular and systemic phenotypes. Targeting APOE-associated metabolic pathways may offer opportunities to alter disease-related phenotypes and consequently, attenuate disease risk and impart resilience to multiple neurodegenerative diseases. We review the molecular, cellular, and tissue-level alterations to lipid metabolism that arise from different APOE isoforms. These changes in lipid metabolism could help to elucidate disease mechanisms and tune neurodegenerative disease risk and resilience.

Enhanced Detection of Charged N-Glycans in the Brain by Infrared Matrix-Assisted Laser Desorption Electrospray Ionization Mass Spectrometric Imaging

N-linked glycosylation represents a structurally diverse, complex, co- and posttranslational protein modification that bridges metabolism and cellular signaling. Consequently, aberrant protein glycosylation is a hallmark of most pathological scenarios. Due to their complex nature and non-template-driven synthesis, the analysis of glycans is faced with several challenges, underlining the need for new and improved analytical technologies. Spatial profiling of N-glycans through direct imaging on tissue sections reveals the regio-specific and/or disease pathology correlating tissue N-glycans that serve as a disease glycoprint for diagnosis. Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is a soft hybrid ionization technique that has been used for diverse mass spectrometry imaging (MSI) applications. Here, we report the first spatial analysis of the brain N-linked glycans by IR-MALDESI MSI, leading to a significant increase in the detection of the brain N-sialoglycans. A formalin-fixed paraffin-embedded mouse brain tissue was analyzed in negative ionization mode after tissue washing, antigen retrieval, and pneumatic application of PNGase F for enzymatic digestion of N-linked glycans. We report a comparative analysis of section thickness on the N-glycan detection using IR-MALDESI. One hundred thirty-six unique N-linked glycans were confidently identified in the brain tissue (with an additional 132 unique N-glycans, not reported in GlyConnect), where more than 50% contained sialic acid residues, which is approximately 3-fold higher than the previous reports. This work demonstrates the first application of IR-MALDESI in N-linked glycan imaging of the brain tissue, leading to a 2.5-fold increase in the in situ total brain N-glycan detection compared to the current gold standard of positive-mode matrix-assisted laser desorption/ionization mass spectrometry imaging. This is also the first report of the application of the MSI toward the identification of sulfoglycans in the rodent brain. Overall, IR-MALDESI-MSI presents a sensitive glycan detection platform to identify tissue-specific and/or disease-specific glycosignature in the brain while preserving the sialoglycans without any chemical derivatization.

Screening autism-associated environmental factors in differentiating human neural progenitors with fractional factorial design-based transcriptomics

Research continues to identify genetic variation, environmental exposures, and their mixtures underlying different diseases and conditions. There is a need for screening methods to understand the molecular outcomes of such factors. Here, we investigate a highly efficient and multiplexable, fractional factorial experimental design (FFED) to study six environmental factors (lead, valproic acid, bisphenol A, ethanol, fluoxetine hydrochloride and zinc deficiency) and four human induced pluripotent stem cell line derived differentiating human neural progenitors. We showcase the FFED coupled with RNA-sequencing to identify the effects of low-grade exposures to these environmental factors and analyse the results in the context of autism spectrum disorder (ASD). We performed this after 5-day exposures on differentiating human neural progenitors accompanied by a layered analytical approach and detected several convergent and divergent, gene and pathway level responses. We revealed significant upregulation of pathways related to synaptic function and lipid metabolism following lead and fluoxetine exposure, respectively. Moreover, fluoxetine exposure elevated several fatty acids when validated using mass spectrometry-based metabolomics. Our study demonstrates that the FFED can be used for multiplexed transcriptomic analyses to detect relevant pathway-level changes in human neural development caused by low-grade environmental risk factors. Future studies will require multiple cell lines with different genetic backgrounds for characterising the effects of environmental exposures in ASD.

Modulation of Dietary Choline Uptake in a Mouse Model of Acid Sphingomyelinase Deficiency

Acid sphingomyelinase deficiency (ASMD) is a lysosomal storage disorder caused by mutations in the gene-encoding acid sphingomyelinase (ASM). ASMD impacts peripheral organs in all patients, including the liver and spleen. The infantile and chronic neurovisceral forms of the disease also lead to neuroinflammation and neurodegeneration for which there is no effective treatment. Cellular accumulation of sphingomyelin (SM) is a pathological hallmark in all tissues. SM is the only sphingolipid comprised of a phosphocholine group linked to ceramide. Choline is an essential nutrient that must be obtained from the diet and its deficiency promotes fatty liver disease in a process dependent on ASM activity. We thus hypothesized that choline deprivation could reduce SM production and have beneficial effects in ASMD. Using acid sphingomyelinase knock-out (ASMko) mice, which mimic neurovisceral ASMD, we have assessed the safety of a choline-free diet and its effects on liver and brain pathological features such as altered sphingolipid and glycerophospholipid composition, inflammation and neurodegeneration. We found that the choline-free diet was safe in our experimental conditions and reduced activation of macrophages and microglia in the liver and brain, respectively. However, there was no significant impact on sphingolipid levels and neurodegeneration was not prevented, arguing against the potential of this nutritional strategy to assist in the management of neurovisceral ASMD patients.

Feasibility of transient nuclear Overhauser effect imaging in brain at 7 T

PURPOSE

The nuclear Overhauser effect (NOE) quantification from the steady-state NOE imaging suffers from multiple confounding non-NOE-specific sources, including direct saturation, magnetization transfer, and relevant chemical exchange species, and is affected by B₀ and B₁ ⁺ inhomogeneities. The B₀ -dependent and B₁ ⁺ -dependent data needed for deconvolving these confounding effects would increase the scan time substantially, leading to other issues such as patient tolerability. Here, we demonstrate the feasibility of brain lipid mapping using an easily implementable transient NOE (tNOE) approach.

METHODS

This 7T study used a frequency-selective inversion pulse at a range of frequency offsets between 1.0 and 5.0 parts per million (ppm) and -5.0 and -1.0 ppm relative to bulk water peak. This was followed by a fixed/variable mixing time and then a single-shot 2D turbo FLASH readout. The feasibility of tNOE measurements is demonstrated on bovine serum albumin phantoms and healthy human brains.

RESULTS

The tNOE measurements from bovine serum albumin phantoms were found to be independent of physiological pH variations. Both bovine serum albumin phantoms and human brains showed broad tNOE contributions centered at approximately -3.5 ppm relative to water peak, with presumably aliphatic moieties in lipids and proteins being the dominant contributors. Less prominent tNOE contributions of approximately +2.5 ppm relative to water, presumably from aromatic moieties, were also detected. These aromatic signals were free from any CEST signals.

CONCLUSION

In this study, we have demonstrated the feasibility of tNOE in human brain at 7 T. This method is more scan-time efficient than steady-state NOE and provides NOE measurement with minimal confounders.

Untargeted metabolomics profiling in pediatric patients and adult populations indicates a connection between lipid imbalance and epilepsy

Introduction

Epilepsy is a common central nervous system disorder characterized by abnormal brain electrical activity. We aimed to compare the metabolic profiles of plasma from patients with epilepsy across different etiologies, seizure frequency, seizure type, and patient age to try to identify common disrupted pathways.

Material and methods

We used data from three separate cohorts. The first cohort (PED-C) consisted of 31 pediatric patients with suspicion of a genetic disorder with unclear etiology; the second cohort (AD-C) consisted of 250 adults from the Estonian Biobank (EstBB), and the third cohort consisted of 583 adults ≥ 69 years of age from the EstBB (ELD-C). We compared untargeted metabolomics and lipidomics data between individuals with and without epilepsy in each cohort.

Results

In the PED-C, significant alterations (p-value <0.05) were detected in sixteen different glycerophosphatidylcholines (GPC), dimethylglycine and eicosanedioate (C20-DC). In the AD-C, nine significantly altered metabolites were found, mainly triacylglycerides (TAG), which are also precursors in the GPC synthesis pathway. In the ELD-C, significant changes in twenty metabolites including multiple TAGs were observed in the metabolic profile of participants with previously diagnosed epilepsy. Pathway analysis revealed that among the metabolites that differ significantly between epilepsy-positive and epilepsy-negative patients in the PED-C, the lipid superpathway (p = 3.2*10-4) and phosphatidylcholine (p = 9.3*10-8) and lysophospholipid (p = 5.9*10-3) subpathways are statistically overrepresented. Analogously, in the AD-C, the triacylglyceride subclass turned out to be statistically overrepresented (p = 8.5*10-5) with the lipid superpathway (p = 1.4*10-2). The presented p-values are FDR-corrected.

Conclusion

Our results suggest that cell membrane fluidity may have a significant role in the mechanism of epilepsy, and changes in lipid balance may indicate epilepsy. However, further studies are needed to evaluate whether untargeted metabolomics analysis could prove helpful in diagnosing epilepsy earlier.

CPT1A in AgRP neurons is required for sex-dependent regulation of feeding and thirst

BACKGROUND

Fatty acid metabolism in the hypothalamus has an important role in food intake, but its specific role in AgRP neurons is poorly understood. Here, we examined whether carnitinea palmitoyltransferase 1A (CPT1A), a key enzyme in mitochondrial fatty acid oxidation, affects energy balance.

METHODS

To obtain Cpt1aKO mice and their control littermates, Cpt1a(flox/flox) mice were crossed with tamoxifen-inducible AgRPCreERT2 mice. Food intake and body weight were analyzed weekly in both males and females. At 12 weeks of age, metabolic flexibility was determined by ghrelin-induced food intake and fasting-refeeding satiety tests. Energy expenditure was analyzed by calorimetric system and thermogenic activity of brown adipose tissue. To study fluid balance the analysis of urine and water intake volumes; osmolality of urine and plasma; as well as serum levels of angiotensin and components of RAAS (renin-angiotensin-aldosterone system) were measured. At the central level, changes in AgRP neurons were determined by: (1) analyzing specific AgRP gene expression in RiboTag-Cpt1aKO mice obtained by crossing Cpt1aKO mice with RiboTag mice; (2) measuring presynaptic terminal formation in the AgRP neurons with the injection of the AAV1-EF1a-DIO-synaptophysin-GFP in the arcuate nucleus of the hypothalamus; (3) analyzing AgRP neuronal viability and spine formations by the injection AAV9-EF1a-DIO-mCherry in the arcuate nucleus of the hypothalamus; (4) analyzing in situ the specific AgRP mitochondria in the ZsGreen-Cpt1aKO obtained by breeding ZsGreen mice with Cpt1aKO mice. Two-way ANOVA analyses were performed to determine the contributions of the effect of lack of CPT1A in AgRP neurons in the sex.

RESULTS

Changes in food intake were just seen in male Cpt1aKO mice while only female Cpt1aKO mice increased energy expenditure. The lack of Cpt1a in the AgRP neurons enhanced brown adipose tissue activity, mainly in females, and induced a substantial reduction in fat deposits and body weight. Strikingly, both male and female Cpt1aKO mice showed polydipsia and polyuria, with more reduced serum vasopressin levels in females and without osmolality alterations, indicating a direct involvement of Cpt1a in AgRP neurons in fluid balance. AgRP neurons from Cpt1aKO mice showed a sex-dependent gene expression pattern, reduced mitochondria and decreased presynaptic innervation to the paraventricular nucleus, without neuronal viability alterations.

CONCLUSIONS

Our results highlight that fatty acid metabolism and CPT1A in AgRP neurons show marked sex differences and play a relevant role in the neuronal processes necessary for the maintenance of whole-body fluid and energy balance.

Brain fatty acid and transcriptome profiles of pig fed diets with different levels of soybean oil

BACKGROUND

The high similarity in anatomical and neurophysiological processes between pigs and humans make pigs an excellent model for metabolic diseases and neurological disorders. Lipids are essential for brain structure and function, and the polyunsaturated fatty acids (PUFA) have anti-inflammatory and positive effects against cognitive dysfunction in neurodegenerative diseases. Nutrigenomics studies involving pigs and fatty acids (FA) may help us in better understanding important biological processes. In this study, the main goal was to evaluate the effect of different levels of dietary soybean oil on the lipid profile and transcriptome in pigs' brain tissue.

RESULTS

Thirty-six male Large White pigs were used in a 98-day study using two experimental diets corn-soybean meal diet containing 1.5% soybean oil (SOY1.5) and corn-soybean meal diet containing 3.0% soybean oil (SOY3.0). No differences were found for the brain total lipid content and FA profile between the different levels of soybean oil. For differential expression analysis, using the DESeq2 statistical package, a total of 34 differentially expressed genes (DEG, FDR-corrected p-value < 0.05) were identified. Of these 34 DEG, 25 are known-genes, of which 11 were up-regulated (log2 fold change ranging from + 0.25 to + 2.93) and 14 were down-regulated (log2 fold change ranging from - 3.43 to -0.36) for the SOY1.5 group compared to SOY3.0. For the functional enrichment analysis performed using MetaCore with the 34 DEG, four pathway maps were identified (p-value < 0.05), related to the ALOX15B (log2 fold change - 1.489), CALB1 (log2 fold change - 3.431) and CAST (log2 fold change + 0.421) genes. A "calcium transport" network (p-value = 2.303e-2), related to the CAST and CALB1 genes, was also identified.

CONCLUSION

The results found in this study contribute to understanding the pathways and networks associated with processes involved in intracellular calcium, lipid metabolism, and oxidative processes in the brain tissue. Moreover, these results may help a better comprehension of the modulating effects of soybean oil and its FA composition on processes and diseases affecting the brain tissue.

S1P Released by SGPL1-Deficient Astrocytes Enhances Astrocytic ATP Production via S1PR2,4, Thus Keeping Autophagy in Check: Potential Consequences for Brain Health

Astrocytes are critical players in brain health and disease. Sphingosine-1-phosphate (S1P), a bioactive signaling lipid, is involved in several vital processes, including cellular proliferation, survival, and migration. It was shown to be crucial for brain development. Its absence is embryonically lethal, affecting, inter alia, the anterior neural tube closure. However, an excess of S1P due to mutations in S1P-lyase (SGPL1), the enzyme responsible for its constitutive removal, is also harmful. Of note, the gene SGPL1 maps to a region prone to mutations in several human cancers and also in S1P-lyase insufficiency syndrome (SPLIS) characterized by several symptoms, including peripheral and central neurological defects. Here, we investigated the impact of S1P on astrocytes in a mouse model with the neural-targeted ablation of SGPL1. We found that SGPL1 deficiency, and hence the accumulation of its substrate, S1P, causes the elevated expression of glycolytic enzymes and preferentially directs pyruvate into the tricarboxylic acid (TCA) cycle through its receptors (S1PR_2,4). In addition, the activity of TCA regulatory enzymes was increased, and consequently, so was the cellular ATP content. The high energy load activates the mammalian target of rapamycin (mTOR), thus keeping astrocytic autophagy in check. Possible consequences for the viability of neurons are discussed.

The roles and mechanisms of gut microbiome and metabolome in patients with cerebral infarction

As the most common type of stroke, ischemic stroke, also known as cerebral infarction (CI), with its high mortality and disability rate, has placed a huge burden on social economy and public health. Treatment methods for CI mainly include thrombectomy, thrombolysis, drug therapy, and so on. However, these treatments have certain timeliness and different side effects. In recent years, the gut-brain axis has become a hot topic, and its role in nervous system diseases has been confirmed by increasing evidences. The intestinal microbiota, as an important part of the gut-brain axis, has a non-negligible impact on the progression of CI through mechanisms such as inflammatory response and damage-associated molecular patterns, and changes in the composition of intestinal microbiota can also serve as the basis for predicting CI. At the same time, the diagnosis of CI requires more high-throughput techniques, and the analysis method of metabolomics just fits this demand. This paper reviewed the changes of intestinal microbiota in patients within CI and the effects of the intestinal microbiota on the course of CI, and summarized the therapeutic methods of the intervention with the intestinal microbiota. Furthermore, metabolic changes of CI patients were also discussed to reveal the molecular characteristics of CI and to elucidate the potential pathologic pathway of its interference.

Urine 3-Nitrotyrosine and Serum HDL as Potential Biomarkers of Depression

Depression (MDD) is a leading psychiatric entity worldwide, with a high impact on individual life and public health. In recent years, efforts have been made to elucidate its biological underpinnings. MDD biomarker research provides promise for a better understanding of the biochemical processes involved in its pathogenesis. Oxidative and nitrosative stress (O&NS) and lipid disturbances are reported as major factors favoring the occurrence of depression. A total of 29 patients with MDD and 30 healthy volunteers were examined using the Hamilton Depression Scale (HAM-D), the Hamilton Anxiety Scale (HAM-A), and the Beck Depression Inventory (BDI). Blood and urine were collected to search for potential MDD biomarkers. O&NS parameters and β-amyloid were assessed in the urine, while cholesterol fractions were assessed in the blood. The group of depressed patients was characterized by higher concentrations of urine superoxide dismutase (SOD), 3-nitrotyrosine (3-NT), catalase (CAT), reduced glutathione (GSH), tryptophan (TRY), and serum triglycerides (TGA), along with lower levels of serum high-density lipoprotein (HDL). Elevated urine 3-NT and decreased serum HDL, considered together, were found to have the greatest potential as markers of depression. The study supports the importance of oxidative stress and cholesterol disturbances in MDD. Further research is required to assess their clinical usefulness as markers.

Neurobiological Basis of Aversion-Resistant Ethanol Seeking in C. elegans

Persistent alcohol seeking despite the risk of aversive consequences is a crucial characteristic of alcohol use disorders (AUDs). Therefore, an improved understanding of the molecular basis of alcohol seeking despite aversive stimuli or punishment in animal models is an important strategy to understand the mechanism that underpins the pathology of AUDs. Aversion-resistant seeking (ARS) is characterized by disruption in control of alcohol use featured by an imbalance between the urge for alcohol and the mediation of aversive stimuli. We exploited C. elegans, a genetically tractable invertebrate, as a model to elucidate genetic components related to this behavior. We assessed the seb-3 neuropeptide system and its transcriptional regulation to progress aversion-resistant ethanol seeking at the system level. Our functional genomic approach preferentially selected molecular components thought to be involved in cholesterol metabolism, and an orthogonal test defined functional roles in ARS through behavioral elucidation. Our findings suggest that fmo-2 (flavin-containing monooxygenase-2) plays a role in the progression of aversion-resistant ethanol seeking in C. elegans.

MicroRNA: A Linking between Astrocyte Dysfunction, Mild Cognitive Impairment, and Neurodegenerative Diseases

Simple Summary

Neurodegenerative diseases are complex neurological disorders with a high incidence worldwide in older people, increasing hospital visits and requiring expensive treatments. As a precursor phase of neurodegenerative diseases, cognitive impairment needs to be studied to understand the factors that influence its development and improve patients’ quality of life. The present review compiles possible factors and biomarkers for diagnosing mild cognitive impairment based on the most recent studies involving miRNAs. These molecules can direct the gene expression in multiple cells, affecting their behavior under certain conditions, such as stressing factors. This review encourages further research into biomarkers that identify cognitive impairment in cellular models such as astrocytes, which are brain cells capable of maintaining the optimal conditions for the central nervous system functioning.

Abstract

The importance of miRNAs in cellular processes and their dysregulation has taken significant importance in understanding different pathologies. Due to the constant increase in the prevalence of neurodegenerative diseases (ND) worldwide and their economic impact, mild cognitive impairment (MCI), considered a prodromal phase, is a logical starting point to study this public health problem. Multiple studies have established the importance of miRNAs in MCI, including astrocyte regulation during stressful conditions. Additionally, the protection mechanisms exerted by astrocytes against some damage in the central nervous system (CNS) lead to astrocytic reactivation, in which a differential expression of miRNAs has been shown. Nevertheless, excessive reactivation can cause neurodegeneration, and a clear pattern defining the equilibrium point between a neuroprotective or detrimental astrocytic phenotype is unknown. Therefore, the miRNA expression has gained significant attention to understand the maintenance of brain balance and improve the diagnosis and treatment at earlier stages in the ND. Here, we provide a comprehensive review of the emerging role of miRNAs in cellular processes that contribute to the loss of cognitive function, including lipotoxicity, which can induce chronic inflammation, also considering the fundamental role of astrocytes in brain homeostasis.

Distinct brain lipid signatures in response to low-level PM2.5 exposure in a 3xTg-Alzheimer's disease mouse inhalation model

Fine particulate matter (PM2.5) poses a significant risk to human health. The molecular mechanisms underlying low-level PM2.5-induced neurotoxicity in the central nervous system remain unclear. In addition, changes in lipids in response to PM2.5 exposure have not yet been fully elucidated. In this study, 3xTg-Alzheimer's disease (AD) mice experienced continuous whole-body exposure to non-concentrated PM2.5 for three consecutive months, while control mice inhaled particulate matter-filtered air over the same time span. A liquid chromatography-mass spectrometry-based lipidomic platform was used to determine the distinct lipid profiles of various brain regions. The average PM2.5 concentration during the exposure was 11.38 μg/m3, which was close to the regulation limits of USA and Taiwan. The partial least squares discriminant analysis model showed distinct lipid profiles in the cortex, hippocampus, and olfactory bulb, but not the cerebellum, of mice in the exposure group. Increased levels of fatty acyls, glycerolipids, and sterol lipids, as well as the decreased levels of glycerophospholipids and sphingolipids in PM2.5-exposed mouse brains may be responsible for the increased energy demand, membrane conformation, neuronal loss, antioxidation, myelin function, and cellular signaling pathways associated with AD development. Our research suggests that subchronic exposure to low levels of PM2.5 may cause neurotoxicity by changing the lipid profiles in a susceptible model. Lipidomics is a powerful tool to study the early effects of PM2.5-induced AD toxicity.

Associations of the Lipidome with Ageing, Cognitive Decline and Exercise Behaviours

One of the most recognisable features of ageing is a decline in brain health and cognitive dysfunction, which is associated with perturbations to regular lipid homeostasis. Although ageing is the largest risk factor for several neurodegenerative diseases such as dementia, a loss in cognitive function is commonly observed in adults over the age of 65. Despite the prevalence of normal age-related cognitive decline, there is a lack of effective methods to improve the health of the ageing brain. In light of this, exercise has shown promise for positively influencing neurocognitive health and associated lipid profiles. This review summarises age-related changes in several lipid classes that are found in the brain, including fatty acyls, glycerolipids, phospholipids, sphingolipids and sterols, and explores the consequences of age-associated pathological cognitive decline on these lipid classes. Evidence of the positive effects of exercise on the affected lipid profiles are also discussed to highlight the potential for exercise to be used therapeutically to mitigate age-related changes to lipid metabolism and prevent cognitive decline in later life.

MeHg exposure impairs both the catecholaminergic and cholinergic systems resulting in motor and non-motor behavioral changes in Drosophila melanogaster

Human exposure to the natural environmental contaminant methylmercury (MeHg) has been associated to adverse health effects. Importantly, the mechanisms by which this organomercurial exerts its neurotoxicity have yet to be fully clarified. Therefore, the aim of this study was to evaluate whether exposure to MeHg alters dopamine (DA) and octopamine (OA) levels, acetylcholinesterase (AChE) activity and impacts both motor and non-motor behaviours. We studied the effect of MeHg by feeding 1-2 d old flies (male and females) with 25 and 50 μM MeHg for 4 d and determined effects on survival, motor and non-motor behaviours, oxidative stress, AChE and tyrosine hydroxylase (TH) activities, as well as DA and OA levels. We found that Drosophila melanogaster (D. melanogaster) exposed to MeHg showed a reduction in survival rate, associated with the inhibition of AChE and TH activities in head of flies and decreased DA and OA levels. These changes were accompanied by behavioural alterations, such as locomotor deficit and increased grooming behaviour, in addition to an increase in oxidative stress markers both in head and in body of flies, and an increase in glutathione-S-transferase (GST) activity in head of flies. Collectively, our data support the hypothesis that MeHg neurotoxicity is associated with altered OA and DA levels, AChE inhibition, which may serve, at least in part, as the underpinnings of both motor and non-motor behavioural changes.

Fenretinide in Cancer and Neurological Disease: A Two-Face Janus Molecule

Recently, several chemotherapeutic drugs have been repositioned in neurological diseases, based on common biological backgrounds and the inverse comorbidity between cancer and neurodegenerative diseases. Fenretinide (all-trans-N-(4-hydroxyphenyl) retinamide, 4-HPR) is a synthetic derivative of all-trans-retinoic acid initially proposed in anticancer therapy for its antitumor effects combined with limited toxicity. Subsequently, fenretinide has been proposed for other diseases, for which it was not intentionally designed for, due to its ability to influence different biological pathways, providing a broad spectrum of pharmacological effects. Here, we review the most relevant preclinical and clinical findings from fenretinide and discuss its therapeutic role towards cancer and neurological diseases, highlighting the hormetic behavior of this pleiotropic molecule.

Mass Spectrometry-Based Analysis of Lipid Involvement in Alzheimer’s Disease Pathology—A Review

Irregularities in lipid metabolism have been linked to numerous neurodegenerative diseases. The roles of abnormal brain, plasma, and cerebrospinal fluid (CSF) lipid levels in Alzheimer’s disease (AD) onset and progression specifically have been described to a great extent in the literature. Apparent hallmarks of AD include, but are not limited to, genetic predisposition involving the APOE Ɛ4 allele, oxidative stress, and inflammation. A common culprit tied to many of these hallmarks is disruption in brain lipid homeostasis. Therefore, it is important to understand the roles of lipids, under normal and abnormal conditions, in each process. Lipid influences in processes such as inflammation and blood–brain barrier (BBB) disturbance have been primarily studied via biochemical-based methods. There is a need, however, for studies focused on uncovering the relationship between lipid irregularities and AD by molecular-based quantitative analysis in transgenic animal models and human samples alike. In this review, mass spectrometry as it has been used as an analytical tool to address the convoluted relationships mentioned above is discussed. Additionally, molecular-based mass spectrometry strategies that should be used going forward to further relate structure and function relationships of lipid irregularities and hallmark AD pathology are outlined.

Effects of Familial Alzheimer's Disease Mutations on the Assembly of a β-Hairpin Peptide Derived from Aβ16-36

Familial Alzheimer's disease (FAD) is associated with mutations in the β-amyloid peptide (Aβ) or the amyloid precursor protein (APP). FAD mutations of Aβ were incorporated into a macrocyclic peptide that mimics a β-hairpin to study FAD point mutations K16N, A21G, E22Δ, E22G, E22Q, E22K, and L34V and their effect on assembly, membrane destabilization, and cytotoxicity. The X-ray crystallographic structures of the four E22 mutant peptides reveal that the peptides assemble to form the same compact hexamer. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) experiments reveal that the mutant FAD peptides assemble as trimers or hexamers, with peptides that have greater positive charge assembling as more stable hexamers. Mutations that increase the positive charge also increase the cytotoxicity of the peptides and their propensity to destabilize lipid membranes.