Structural and functional roles of ether lipids

Alterations in ether phospholipids metabolism activate the conserved UPR-Xbp1- PDIA3/ERp60 signaling to maintain intestinal homeostasis

Intestinal epithelium regeneration and homeostasis must be tightly regulated. Alteration of epithelial homeostasis is a major contributing factor to diseases such as colorectal cancer and inflammatory bowel diseases. Many pathways involved in epithelial regeneration have been identified, but more regulators remain undiscovered. Metabolism has emerged as an overlooked regulator of intestinal epithelium homeostasis. Using the model organism Drosophila melanogaster, we found that ether lipids metabolism is required to maintain intestinal epithelial homeostasis. Its dysregulation in intestinal progenitors causes the activation of the unfolded protein response of the endoplasmic reticulum (UPR) that triggers Xbp1 and upregulates the conserved disulfide isomerase PDIA3/ERp60. Activation of the Xbp1-ERp60 signaling causes Jak/Stat-mediated increase in progenitor cells, compromising epithelial barrier function and survival in males but not females. This study identified ether lipids-PDIA3/ERp60 as a key regulator of intestinal progenitor homeostasis in health that, if altered, causes pathological conditions in the intestinal epithelium.

Association of PM2.5-bound multiple metals co-exposure with early cardiovascular damage: A panel study in young adults combining metabolomics

The association of individual metals in PM2.5 with cardiovascular damage has been established in previous studies, but there are fewer studies on co-exposure to multiple metals and potential metabolic alterations in cardiovascular damage. To investigate the early cardiovascular effects of multiple metals and the mediating effects of metabolites, we conducted a panel study on young adults from 2017 Winter to 2018 Autumn in Caofeidian, China. A total of 180 serum samples were analyzed for metabolomic profiles using liquid chromatography-mass spectrometry. The associations between personal metal exposure, metabolite levels, and indicators of cardiovascular injury were analyzed by linear mixed-effects modeling (LME) and Bayesian kernel machine regression (BKMR). Metabolomic analyses showed 79 metabolites in the serum of healthy adults changed significantly between seasons and all metabolites were strongly associated with toxic metals. Additionally, differential metabolites were enriched in seven metabolic pathways and activated by metal exposure, such as Butanoate metabolism and Linoleic acid metabolism. BKMR model interpreted that the overall effect of metals mixture was negatively associated with Capryloyl glycine and Sphinganine and Sb mainly contributed to the effect. The results of mediation analysis revealed that the association between V and VEGF was mediated by Diethylhexyl with a partial proportion of 13.4%. Furthermore, the result also found the association between CerP(d18:1/26:1(17Z)) and ET-1 was mediated by TGFβ1 with a proportion of 53.4%. Our findings suggested that multiple metal exposure was associated with metabolomic changes of cardiovascular damage in young adults, and may simultaneously affect the metabolomic changes by inducing oxidative stress and inflammation.

Hippo pathway activation causes multiple lipid derangements in a murine model of cardiomyopathy

Metabolic reprogramming occurs in cardiomyopathy and heart failure contributing to progression of the disease. Activation of cardiac Hippo pathway signaling has been implicated in mediating mitochondrial dysfunction and metabolic reprogramming in cardiomyopathy, albeit influence of Hippo pathway on lipid profile is unclear. Using a dual-omics approach, we determined alterations of cardiac lipids in a mouse model of cardiomyopathy due to enhanced Hippo signaling and explored molecular mechanisms. Lipidomic profiling discovered multiple alterations in lipid classes, notably reduction of triacylglycerol, diacylglycerol, phospholipids and ether lipids, and elevation of sphingolipids and lysophosphatidylcholine. Mechanistically, we found downregulated expression of PPARα and PGC-1α at mRNA and protein levels, and downregulated expression of PPARα-target genes, indicating attenuated transcriptional activity of PPARα/PGC-1α. Lipidomics-guided transcriptomic analysis revealed dysregulated expression of gene sets that were responsible for enhanced biosynthesis of ceramides, suppression of TG biosynthesis, storage, hydrolysis and mitochondrial fatty acid oxidation, and reduction of peroxisome-localized biosynthesis of ether lipids. Collectively, Hippo pathway activation with attenuated PPARα/PGC-1α signaling is the underlying mechanism for alterations in cardiac lipids in cardiomyopathy and failing heart.

Impaired lipid homeostasis and elevated lipid oxidation of erythrocyte membrane in adolescent depression

Adolescent depression is a globally concerned mental health issue, the pathophysiological mechanisms of which remain elusive. Membrane lipids play a crucial role in brain development and function, potentially serving as a crossroad for the abnormalities in neurotransmitters, neuroendocrine, inflammation, oxidative stress, and energy metabolism observed in depressed adolescents. The primary aim of this study was to investigate the erythrocyte membrane lipid profile in adolescent depression. A total of 2838 erythrocyte membrane lipids were detected and quantified in 81 adolescents with depression and 67 matched healthy adolescents using ultra-high performance liquid chromatography-mass spectrometry. Depressed adolescents exhibited significantly different membrane lipid characteristics compared to healthy controls. Specifically, the levels of cholesterol, sphingomyelins, and ceramides were increased, while ether lipids were decreased in patients. Moreover, the patients showed reduced polyunsaturated fatty acids and elevated lipophilic index in membrane, suggesting diminished membrane fluidity. The higher oxidized membrane lipids and plasma malondialdehyde were observed in adolescent depression, indicating the presence of oxidative stress. Importantly, membrane lipid damage was associated with more severe depressive symptoms and worse cognitive function in patients. In addition, reduced polyunsaturated fatty acids and membrane fluidity may be partly responsible for the blunted niacin skin flushing response found in depressed adolescents. In conclusion, our results reveal impaired erythrocyte membrane lipid homeostasis in adolescents with depression, which may implicate membrane dysfunction in the brain. These findings offer new insights into the underlying molecular mechanisms of adolescent depression, highlighting the potential of counteracting membrane damage as a promising avenue for future therapeutic interventions.

Plasma lipidomic analysis reveals disruption of ether phosphatidylcholine biosynthesis and facilitates early detection of hepatitis B-related hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is the third deadliest malignant tumor worldwide. Most patients are initially diagnosed as HCC at advanced stages and are too late for radical treatment by surgery, resulting in poor prognosis. Over 50% of the HCC patients are caused by hepatitis B virus (HBV) infection. Therefore, effective early identification of HCC in the high-risk population with HBV infection is crucial for early intervention of HCC.

METHODS

We employed plasma lipidomics to identify critical lipid classes associated with tumorigenesis in the high-risk population with HBV infection. Potential regulatory mechanisms are validated at multi-omic levels. A machine learning algorithm is used for feature selection and diagnostic modelling, and performance of the models is evaluated by ROC curves.

RESULTS

We unveiled varied profiles of plasma lipid metabolites in a cohort of 57 HBV-related HCC subjects, 57 HBV-related liver cirrhosis (LC) subjects and 61 chronic hepatitis B (CHB) subjects with matched age, sex and HBV status. We identified a correlation of the ether phosphatidylcholine (PC) synthesis with hepatocarcinogenesis in patients with HBV-related liver diseases. The diagnostic models achieved an area under ROC curve (AUC) of 0.849 for discriminating HCC from CHB and an AUC of 0.829 for discriminating HCC from LC.

CONCLUSIONS

We illustrate the role of ether PC in hepatocarcinogenesis upon HBV infection and provide novel effective markers for early detection of HCC in a cohort with HBV infection.

Distinctive lipidomic responses induced by polystyrene micro- and nano-plastics in zebrafish liver cells

Despite growing awareness of the size-dependent toxicity caused by micro- and nano-plastics (MNPs) in fish, the modulation of the liver lipidome as a function of particle size has not been thoroughly investigated. This study explores the subcellular and molecular responses induced by polystyrene microplastics (MPs, 1 µm) and nano-plastics (NPs, 52 nm) in zebrafish liver (ZFL) cells, with a focus on the modulation of the cell's lipidome and gene expression profiles. Both particle sizes are readily internalized by ZFL cells; however, NPs had a more pronounced impact compared to MPs. Lipidomic analysis revealed that MPs decreased polyunsaturated phospholipids, while NPs increased ether-linked phosphatidylcholines (PC-Ps/PCOs). Gene expression analysis showed that high concentrations of MPs down-regulated the expression of fatty acid synthesis related genes, and significantly downregulated the microsomal triglyceride transfer protein (mtp) gene, indicating a perturbation in lipid storage metabolism, which was not observed for NP exposure. In contrast, NPs induced a dose-dependent accumulation of lipids, suggesting increased lipid droplet formation and an activation of ceramide-mediated apoptosis pathway. These findings provide new insights into the molecular mechanisms of MNP toxicity and emphasize the importance of considering particle size when assessing environmental and health risks. Furthermore, this study highlights the potential of lipidomics for elucidating the mechanisms underlying MNP toxicity, prompting further research into of the long-term consequences of exposure.

Alkylglycerol enhances myogenesis and regulates ether-phospholipid metabolism in C2C12 myoblasts

1-O-Alkylglycerol (AKG), a lipid characteristic of marine organisms, possesses an ether-linked alkyl chain on its glycerol backbone. AKG exhibits various biological activities, including anti-cancer effects, promoting sperm motility, and stimulating immune response. Metabolically, AKG is converted into alkyl- and alkenyl-phospholipids (PLs), which are key components of the cell membrane and play essential roles in maintaining membrane homeostasis and cellular functions. However, the influence of AKG on myogenesis and ether-type PL metabolism in muscle cells remains unknown. This study evaluated the effects of AKG on myogenic differentiation and ether-PL metabolism in mouse C2C12 myoblasts. During differentiation, cells were treated with 10-20 μM 1-O-octadecyl-glycerol (batyl alcohol) and 1-O-hexadecyl-glycerol (chimyl alcohol). By day 7 of differentiation, myotube size had increased in cells treated with AKGs. Comparative tests using compounds with similar or partial structures, including monoacylglycerol and alkenylglycerol, demonstrated that this activity was linked to the structural features of AKG. Conversely, myotube growth was insufficient after treatment with 1-O-dodecyl-glycerol, which contains a shorter alkyl chain. Additionally, batyl alcohol treatment elevated the levels of ether-phosphatidylcholine (PC) molecular species, including e-PC38:4 and e-PC38:5, those are presumed to bind polyunsaturated fatty acids. Chimyl alcohol treatment also increased ether-PC species, including e-PC36:4 and e-PC36:5 while monoacylglycerol did not alter ether-PC levels. These findings suggest that AKG plays a crucial role in membrane dynamics during myogenesis through metabolic conversion to ether-PLs, providing novel insights into muscle homeostasis to contribute to developing nutritional strategies and preventing and treating muscle diseases.

Effect of extraction solvents on the lipid profiles and volatile compounds of fish roe phospholipids

This study aimed to elucidate the effect of extraction solvents on the lipid profiles and volatile compounds in large yellow croaker roe phospholipids (LYPLs) with chloroform/methanol (CM), ethanol/ethanol (EE), and ethanol/hexane (EH). The results demonstrated that CM-extracted LYPLs exhibited the lowest oxidation levels, while EE-extracted LYPLs contained the highest polyunsaturated fatty acids (PUFAs) content. EH extraction was more effective for monounsaturated fatty acids (MUFAs) in LYPLs but was less effective for polar lipids. Across solvents, 410 lipids were identified, with phosphatidylcholine (PC) predominating in all LYPLs groups. The study detected 97 volatiles, with CM-extracted LYPLs showing notably high in pyrazines and benzenes. A total of 65 lipids and 47 volatiles distinguished the three LYPLs groups. Correlation analysis revealed a synergistic effect between PUFAs and lysophosphatidylcholine (LPC), increasing the production of volatile compounds associated with oxidation. These results offered new insights for optimizing future solvent extraction of marine phospholipids.

Reference Intervals of Serum Metabolites and Lipids of a Healthy Chinese Population Determined by Liquid Chromatography-Mass Spectrometry

Background: Metabolomics serves as a very useful tool for elucidating disease mechanisms and identifying biomarkers. Establishing reference intervals (RIs) of metabolites in a healthy population is crucial to the application of metabolomics in life sciences and clinics. Methods: We enrolled 615 healthy Chinese adults aged between 21 and 85 years. Their health status was ascertained through clinical examinations, biochemical parameters, and medical history. Targeted metabolomics and lipidomics analyses were applied to quantify 705 metabolites and lipids in the serum, establishing RIs and investigating the effect of sex and age on the metabolome and lipidome. Results: This study is the first large-scale effort in China to establish RIs for metabolites in the apparently healthy population. We found that most of the sex-related metabolites, including amino acids, acyl-carnitines and triacylglycerols, had higher concentrations in males, while the other sex-related lipids showed higher concentrations in females. Most of the age-related metabolites increased with age, including those associated with protein synthesis, nitric oxide synthesis, energy metabolism, and lipid metabolism. Conclusions: This study gives the reference intervals of the healthy Chinese metabolome and lipidome and their relationship with sex and age, which facilitates life sciences and precision medicine, especially for disease research and biomarker discovery.

Direct Current Stimulation (DCS) Modulates Lipid Metabolism and Intercellular Vesicular Trafficking in SHSY-5Y Cell Line: Implications for Parkinson's Disease

The modulation of the brain's electrical activity for therapeutic purposes has recently gained attention, supported by the promising results obtained through the non-invasive application of transcranial direct current stimulation (tDCS) in the treatment of neurodegenerative and neurological diseases. To optimize therapeutic efficacy, it is crucial to investigate the cellular and molecular effects of tDCS. This will help to identify important biomarkers, predict patient's response and develop personalized treatments. In this study, we applied direct current stimulation (DCS) to a neural cell line, using mild currents over short periods of time (0.5 mA, 20 min), with 24-h intervals. We observed that DCS induced changes in the cellular lipidome, with transient effects observed after a single stimulation (lasting 24 h) and more significant, long-lasting effects (up to 72 h) after repeated stimulation cycles. In neural cells, multiple DCS treatment modulated structural membrane lipids (PE, PS, PI), downregulated glycerol lipids with ether-linked fatty acids and pro-inflammatory lipids (ceramides and lyso-glycerophospholipids) (p ≤ 0.005). Multiple DCS sessions altered transcriptional activity by decreasing the expression of inflammatory cytokines (TNF-α, p ≤ 0.05; IL-1β, p ≤ 0.01), while increasing the expression of neuroprotective factors such as heme oxygenase-1 (p ≤ 0.0001) and brain-derived neurotrophic factor (p ≤ 0.05), as well as proteins involved in vesicular transport (SNARE, sorting nexins and seipin and α-synuclein; p ≤ 0.05). In addition, DCS enhanced the release of extracellular vesicles, with repeated stimulations significantly increasing the release of exosomes threefold. In conclusion, while a single electrical stimulation induces transient metabolic changes with limited phenotypic effects, repeated applications induce a broader and deeper modulation of lipid species. This may lead to a neuroprotective and neuroplasticity-focussed transcriptional profile, potentially supporting the therapeutic effects of tDCS at the cellular and molecular level in patients..

Integrating lipidomics and metabolomics to reveal biomarkers of fat deposition in chicken meat

Local chicken breeds in China are highly regarded for their superior meat flavor. This study utilized lipidomics and non-targeted metabolomics to identify biomarkers influencing intramuscular fat (IMF) deposition in the breast muscle of 42- and 180-day-old Jingyuan chickens. Results revealed that IMF content was higher in the breast muscle of 180-day-old Jingyuan chickens compared to 42-day-old chickens (P < 0.01). We identified 248 differentially expressed lipids (DELs) and 1042 differentially expressed metabolites (DEMs). The breast muscle of 180-day-old chickens contained higher levels of TG, fatty acid (FA) and cholesteryl ester (CE), with C16:1 and C18:1 being particularly abundant. Integration of non-targeted metabolomic analyses emphasized glycerolipid metabolism and vitamin digestion and absorption as the main pathways distinguishing between 42- and 180-day-old chickens. Additionally, the differential metabolites LysoPS 18:1, LysoPC 20:3, LysoPC 18:2, LysoPI 20:3, and Pantothenic acid contributed to enhanced meat flavor in Jingyuan chickens.

msiFlow: automated workflows for reproducible and scalable multimodal mass spectrometry imaging and microscopy data analysis

Multimodal imaging by matrix-assisted laser desorption ionisation mass spectrometry imaging (MALDI MSI) and microscopy holds potential for understanding pathological mechanisms by mapping molecular signatures from the tissue microenvironment to specific cell populations. However, existing software solutions for MALDI MSI data analysis are incomplete, require programming skills and contain laborious manual steps, hindering broadly applicable, reproducible, and high-throughput analysis to generate impactful biological discoveries. Here, we present msiFlow, an accessible open-source, platform-independent and vendor-neutral software for end-to-end, high-throughput, transparent and reproducible analysis of multimodal imaging data. msiFlow integrates all necessary steps from raw data import to analytical visualisation along with state-of-the-art and self-developed algorithms into automated workflows. Using msiFlow, we unravel the molecular heterogeneity of leukocytes in infected tissues by spatial regulation of ether-linked phospholipids containing arachidonic acid. We anticipate that msiFlow will facilitate the broad applicability of MSI in multimodal imaging to uncover context-dependent cellular regulations in disease states.

Consuming a modified Mediterranean ketogenic diet reverses the peripheral lipid signature of Alzheimer's disease in humans

BACKGROUND

Alzheimer's disease (AD) is a major neurodegenerative disorder with significant environmental factors, including diet and lifestyle, influencing its onset and progression. Although previous studies have suggested that certain diets may reduce the incidence of AD, the underlying mechanisms remain unclear.

METHOD

In this post-hoc analysis of a randomized crossover study of 20 elderly adults, we investigated the effects of a modified Mediterranean ketogenic diet (MMKD) on the plasma lipidome in the context of AD biomarkers, analyzing 784 lipid species across 47 classes using a targeted lipidomics platform.

RESULTS

Here we identified substantial changes in response to MMKD intervention, aside from metabolic changes associated with a ketogenic diet, we identified a a global elevation across all plasmanyl and plasmenyl ether lipid species, with many changes linked to clinical and biochemical markers of AD. We further validated our findings by leveraging our prior clinical studies into lipid related changeswith AD (n = 1912), and found that the lipidomic signature with MMKD was inversely associated with the lipidomic signature of prevalent and incident AD.

CONCLUSIONS

Intervention with a MMKD was able to alter the plasma lipidome in ways that contrast with AD-associated patterns. Given its low risk and cost, MMKD could be a promising approach for prevention or early symptomatic treatment of AD.

Glial peroxisome dysfunction induces axonal swelling and neuroinflammation in Drosophila

Glial cells are known to influence neuronal functions through glia-neuron communication. The present study aims to elucidate the mechanism behind peroxisome-mediated glia-neuron communication using Drosophila neuromuscular junction (NMJ) as a model system. We observe a high abundance of peroxisomes in the abdominal NMJ of adult Drosophila. Interestingly, glia-specific knockdown of peroxisome import receptor protein, Pex5, significantly increases axonal area and volume and leads to axon swelling. The enlarged axonal structure is likely deleterious, as the flies with glia-specific knockdown of Pex5 exhibit age-dependent locomotion defects. In addition, impaired peroxisomal ether lipid biosynthesis in glial cells also induces axon swelling. Consistent with our previous work, defective peroxisomal import function upregulates pro-inflammatory cytokine upd3 in glial cells, while glia-specific overexpression of upd3 induces axonal swelling. Furthermore, motor neuron-specific activation of the JAK-STAT pathway through hop overexpression results in axon swelling. Our findings demonstrated that impairment of glial peroxisomes alters axonal morphology, neuroinflammation, and motor neuron function.

Peroxisome inter-organelle cooperation in Drosophila

Many cellular functions are compartmentalized within the optimized environments of organelles. However, processing or storage of metabolites from the same pathway can occur in multiple organelles. Thus, spatially separated organelles need to cooperate functionally. Coordination between organelles in different specialized cells is also needed, with shared metabolites passed via circulation. Peroxisomes are membrane-bounded organelles responsible for cellular redox and lipid metabolism in eukaryotic cells. Peroxisomes coordinate with other organelles including mitochondria, endoplasmic reticulum, lysosomes, and lipid droplets. This functional coordination requires, or is at least enhanced by, direct contact between peroxisomes and other organelles. Peroxisome dysfunction in humans leads to multiorgan effects including neurological, metabolic, developmental, and age-related diseases. Thus, increased understanding of peroxisome coordination with other organelles, especially cells in various organs is essential. Drosophila melanogaster (fruit fly) has emerged recently as an effective animal model for understanding peroxisomes. Here we review current knowledge of pathways regulating coordination between peroxisomes with other organelles in flies, speculating about analogous roles for conserved Drosophila genes encoding proteins with known organelle coordinating roles in other species.

Enhanced protection for interfacial lipid ozonolysis by sulfur-containing amino acids

Sulfur-containing amino acids have been proposed as drugs for lipid oxidation associated with diseases for a long time, but the molecular-level mechanism on the effectiveness of sulfur-containing amino acids against lipid oxidation remains elusive. In this work, with the interfacial sensitivity mass spectrometry method, oxidation of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol (POPG), a widely used model lipid, was significantly inhibited on hung droplet surface in presence of sulfur-containing amino acids, such as cysteine (Cys) and methionine (Met). Both the Cys and Met showed a self-sacrificing protection. The amino acids with -S-R tails (R referring to methyl or t-butyl group) showed more effective against POPG oxidation than those with -SH tails, and this process was not related to the conformations of amino acids. The low effectiveness of Cys during the interfacial chemistry was proved to arise from the formation of disulfide bond. This study extends the current understanding of chemistry of sulfur-containing amino acids and provides insights to aid the sulfur-containing amino acids against cell oxidation.

Can chick meconium serve as a source of biomarkers linked to hatchling quality and the age of parent stock?

One possible approach to selecting chicks based on quality involves identifying biomarkers in biological samples. Concurrently, understanding the metabolic profile of chicks from different-aged breeders is essential for developing strategies to mitigate the age-related effects on hatchability. This study investigated whether chick quality and breeder age influence the metabolic profile of layer chick meconium. A total of 143 chicks from laying breeder hens, categorized as young, middle-aged or old, were visually assessed for quality, and meconium samples were collected for metabolomic analysis. Sixteen metabolites were found to be associated with good-quality chicks across all breeder ages, with an overall accuracy of 81.94 %. Using metabolite profiles, the accuracy for predicting young-hen-chick quality was 93.2 %, with high sensitivity (92.30 %) and specificity (93.75 %). Four metabolites were associated with poor-quality chicks with an overall accuracy of 77.53 %. Partial least squares discriminant analysis (PLS-DA) revealed enhanced metabolite separation in good-quality chicks, with five metabolites exhibiting high area under the curve (AUC) values (>90 %) in chicks from young hens compared to chicks from hens of other ages, including metabolites related to energy metabolism, hormonal activity, vitamin D synthesis and peptide constitution. Disregarding maternal age, five metabolites varied between good- and poor-quality chicks, but with a low accuracy of 61.26 % for quality discrimination. Chicks from young, middle-aged, and old hens exhibited 12, 11, and 2 metabolites that varied the expression between good and poor qualities, with accuracies for predicting good-quality chicks of 74.46 %, 70.83 %, and 51.06 %, respectively. Certain metabolites with 70 < AUC < 80 % have emerged as potential biomarkers for distinguishing between good- and poor-quality layer chicks. These include metabolites related to energy and growth metabolism, tryptophan and methionine metabolism, antioxidants and some with no known function in embryos. This work identified potential metabolites that can be investigated to mitigate the effects of hen age on hatchability. Additionally, several metabolites have emerged as potential biomarkers for distinguishing between good- and poor-quality chicks, depending on the breeder's age.

The Rice Online Expression Profiles Array Database Version 2 (ROADv2): An Interactive Atlas for Rice Functional Genomics

The Rice Online expression profiles Array Database version 2 (ROADv2; https://roadv2.khu.ac.kr ), an enhanced database for rice gene expression analysis, transitions from the previous microarray platforms to RNA-Seq data for improved accuracy. It encompasses 328 datasets from diverse experimental series, including anatomy, abiotic and biotic stress, hormone response, and nutrient starvation. Key updates include gene annotation (upgraded to RGAP version 7) and functional enrichment data (utilizing recent Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) versions). ROADv2 debuts protein-protein interaction (PPI) network analysis and broadens interactive visualization across all features. Gene expression data are segmented into anatomy, biotic, abiotic, nutrient, and hormone categories, with user-interactive heatmaps displaying normalized log2 expression and log2 fold change data. Coexpression correlation analysis identifies genes with similar patterns, visualized through interactive network graphs. Functional enrichment tools display GO and KEGG analyses with significant terms emphasized in various formats. PPI network analysis integrates coexpression data to enhance prediction accuracy. Validation studies affirm the database's reliability, demonstrating reproducible tissue/organ-specific expression patterns. ROADv2 provides a comprehensive resource for rice functional genomics studies.

White matter lipidome alterations in the schizophrenia brain

Numerous brain imaging studies have reported white matter alterations in schizophrenia, but the lipidome analysis of the corresponding tissue remains incomplete. In this study, we investigated the lipidome composition of six subcortical white matter regions corresponding to major axonal tracks in both control subjects and schizophrenia patients. All six regions exhibited a consistent pattern of quantitative lipidome alterations in schizophrenia, involving myelin-forming and mitochondria associated lipid classes. While alteration levels of myelin-forming lipids, particularly sphingolipids, aligned with the extent of the myelin changes reported in structural brain imaging studies, a significant decrease of mitochondria in the white matter, indicated by the lipidome alterations, was not previously investigated. To verify this effect, we performed lipidome analysis in a larger set of individuals and in the mitochondria-enriched membrane fraction, as well as directly quantified mitochondrial content. Our results suggest a substantial reduction of the mitochondrial quotient accompanied by the imbalance in myelin lipids in schizophrenia white matter.

FAF2 is a bifunctional regulator of peroxisomal homeostasis and saturated lipid responses

Exposure to saturated fatty acids (SFAs), such as palmitic acid, can lead to cellular metabolic dysfunction known as lipotoxicity. Although canonical adaptive metabolic processes like lipid storage or desaturation are known cellular responses to saturated fat exposure, the link between SFA metabolism and organellar biology remains an area of active inquiry. We performed a genome-wide CRISPR knockout screen in human epithelial cells to identify modulators of SFA toxicity. The screen revealed peroxisomal proteins, especially those that impact ether lipid synthesis, as important regulators of lipotoxicity. We identified Fas-associated factor family member 2 (FAF2) as a critical bifunctional co-regulator of peroxisomal and fatty acid biology. We further uncovered a new biological function for the ubiquitin-regulatory X (UBX) and UAS thioredoxin-like domains of FAF2, demonstrating their requirement for peroxisomal protein abundance and SFA-induced cellular stress. Our work highlights the role of FAF2 in regulating peroxisomal abundance and function, and the peroxisome as a key organelle in the cellular response to SFAs.

"Head-to-Toe" Lipid Properties Govern the Binding and Cargo Transfer of High-Density Lipoprotein

The viscoelastic properties of biological membranes are crucial in controlling cellular functions and are determined primarily by the lipids' composition and structure. This work studies these properties by varying the structure of the constituting lipids in order to influence their interaction with high-density lipoprotein (HDL) particles. Various fluorescence-based techniques were applied to study lipid domains, membrane order, and the overall lateral as well as the molecule-internal glycerol region mobility in HDL-membrane interactions (i.e., binding and/or cargo transfer). The analysis of interactions with HDL particles and various lipid phases revealed that both fully fluid and some gel-phase lipids preferentially interact with HDL particles, although differences were observed in protein binding and cargo exchange. Both interactions were reduced with ordered lipid mixtures containing cholesterol. To investigate the mechanism, membranes were prepared from single-lipid components, enabling step-by-step modification of the lipid building blocks. On a biophysical level, the different mixtures displayed varying stiffness, fluidity, and hydrogen bond network changes. Increased glycerol mobility and a strengthened hydrogen bond network enhanced anchoring interactions, while fluid membranes with a reduced water network facilitated cargo transfer. In summary, the data indicate that different lipid classes are involved depending on the type of interaction, whether anchoring or cargo transfer.

Female-age-dependent changes in the lipid fingerprint of the mammalian oocytes

STUDY QUESTION

Can oocyte functionality be assessed by observing changes in their intracytoplasmic lipid droplets (LDs) profiles?

SUMMARY ANSWER

Lipid profile changes can reliably be detected in human oocytes; lipid changes are linked with maternal age and impaired developmental competence in a mouse model.

WHAT IS KNOWN ALREADY

In all cellular components, lipid damage is the earliest manifestation of oxidative stress (OS), which leads to a cascade of negative consequences for organelles and DNA. Lipid damage is marked by the accumulation of LDs. We hypothesized that impaired oocyte functionality resulting from aging and associated OS could be assessed by changes in LDs profile, hereafter called lipid fingerprint (LF).

STUDY DESIGN, SIZE, DURATION

To investigate if it is possible to detect differences in oocyte LF, we subjected human GV-stage oocytes to spectroscopic examinations. For this, a total of 48 oocytes derived from 26 young healthy women (under 33 years of age) with no history of infertility, enrolled in an oocyte donation program, were analyzed. Furthermore, 30 GV human oocytes from 12 women were analyzed by transmission electron microscopy (TEM). To evaluate the effect of oocytes' lipid profile changes on embryo development, a total of 52 C57BL/6 wild-type mice and 125 Gnpat+/- mice were also used.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Human oocytes were assessed by label-free cell imaging via coherent anti-Stokes Raman spectroscopy (CARS). Further confirmation of LF changes was conducted using spontaneous Raman followed by Fourier transform infrared (FTIR) spectroscopies and TEM. Additionally, to evaluate whether LF changes are associated with developmental competence, mouse oocytes and blastocysts were evaluated using TEM and the lipid dyes BODIPY and Nile Red. Mouse embryonic exosomes were evaluated using flow cytometry, FTIR and FT-Raman spectroscopies.

MAIN RESULTS AND THE ROLE OF CHANCE

Here we demonstrated progressive changes in the LF of oocytes associated with the woman's age consisting of increased LDs size, area, and number. LF variations in oocytes were detectable also within individual donors. This finding makes LF assessment a promising tool to grade oocytes of the same patient, based on their quality. We next demonstrated age-associated changes in oocytes reflected by lipid peroxidation and composition changes; the accumulation of carotenoids; and alterations of structural properties of lipid bilayers. Finally, using a mouse model, we showed that LF changes in oocytes are negatively associated with the secretion of embryonic exosomes prior to implantation. Deficient exosome secretion disrupts communication between the embryo and the uterus and thus may explain recurrent implantation failures in advanced-age patients.

LIMITATIONS, REASONS FOR CAUTION

Due to differences in lipid content between different species' oocytes, the developmental impact of lipid oxidation and consequent LF changes may differ across mammalian oocytes.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings open the possibility to develop an innovative tool for oocyte assessment and highlight likely functional connections between oocyte LDs and embryonic exosome secretion. By recognizing the role of oocyte LF in shaping the embryo's ability to implant, our original work points to future directions of research relevant to developmental biology and reproductive medicine.

STUDY FUNDING/COMPETING INTEREST(S)

This research was funded by National Science Centre of Poland, Grants: 2021/41/B/NZ3/03507 and 2019/35/B/NZ4/03547 (to G.E.P.); 2022/44/C/NZ4/00076 (to M.F.H.) and 2019/35/N/NZ3/03213 (to Ł.G.). M.F.H. is a National Agency for Academic Exchange (NAWA) fellow (GA ULM/2019/1/00097/U/00001). K.F. is a Diamond Grant fellow (Ministry of Education and Science GA 0175/DIA/2019/28). The open-access publication of this article was funded by the Priority Research Area BioS under the program "Excellence Initiative - Research University" at the Jagiellonian University in Krakow. The authors declare no competing interest.

TRIAL REGISTRATION NUMBER

N/A.

Ferroptosis: A Key Driver in Atherosclerosis Progression and Arterial Disease

Atherosclerosis (AS) is a growing global health epidemic and is the leading cause of cardiovascular health problems, including ischemic stroke, coronary artery disease, and peripheral vascular disease. Despite extensive research on the underlying mechanisms of AS, iron remains an under-investigated mediator in the atherosclerotic process. Iron's involvement in AS is primarily linked to the iron-induced programmed cell death process known as ferroptosis. Ferroptosis is initiated in endothelial cells when iron overload triggers the Fenton reaction, resulting in the production of reactive oxygen species (ROS) and lipid peroxides. This oxidative stress damages cellular components, ultimately leading to cell death. The review examines the role of iron overload and ferroptosis in the progression and instability of atherosclerotic plaques. Additionally, we explore the potential therapeutic roles of iron chelators and ROS scavengers in mitigating the adverse effects of ferroptosis. The findings indicate that ferroptosis contributes significantly to the progression and instability of atherosclerotic plaques by promoting oxidative damage and cellular dysfunction. Iron chelators and ROS scavengers have shown promise in reducing ferroptosis-induced damage in endothelial cells. These therapeutic agents can potentially stabilize atherosclerotic plaques and prevent the progression of AS. Ferroptosis is a critical yet under-explored pathway in the development and progression of atherosclerosis. Targeting iron-induced oxidative stress through iron chelation and ROS scavenging presents a promising therapeutic strategy for mitigating the adverse effects of ferroptosis on atherosclerotic plaque stability. Further research is needed to validate these therapeutic approaches and better understand the molecular mechanisms underlying ferroptosis in atherosclerosis.

A novel exosome-like nanovesicles from Cordyceps militaris potentiate immunomodulatory and anti-tumor effect by reprogramming macrophages

AIMS

Fungi-derived exosome-like nanovesicles (ENs) are emerging as a highly promising class of nanoparticles, particularly noted for their cost-effective production. However, their impact on immune regulation and their potential as anti-tumor agents need further exploration. Our study specifically focused on the investigation of the immunomodulatory and anti-tumor properties of ENs derived from Cordyceps militaris, an edible fungus that had achieved large-scale commercial production, referred to as CMDENs.

MAIN METHODS

The ENs of C. militaris were collected through ultra-high-speed centrifugation, followed by characterization of their physicochemical properties and contents. Subsequently, the biological distribution of these vesicles was investigated using in vivo fluorescence imaging experiments. Finally, the immune activation and polarization of macrophages were examined through both in vitro and in vivo experiments.

KEY FINDINGS

Herein, we presented the discovery of CMDENs that were rich in proteins, lipids, flavonoids and alkaloids. Immunomodulatory experiments conducted in vivo demonstrated that CMDENs exhibited protective effects against cyclophosphamide-induced immunosuppression in mice by significantly enhancing macrophage phagocytosis and peripheral blood immune cell counts. Moreover, CMDENs effectively induced the polarization of M0- and M2-like macrophages toward M1-like phenotype by activating MAPKs signaling pathway. Notably, CMDENs exhibited remarkable capabilities in inhibiting tumor growth by reprogramming tumor-associated macrophages and activating tumor-infiltrating T lymphocytes, without any observed toxicity in mice bearing tumors.

SIGNIFICANCE

Our research suggested that CMDENs possessed the potential to be explored as a nano-immunomodulatory agent for cancer.

Radical-directed dissociation mass spectrometry for differentiation and relative quantitation of isomeric ether-linked phosphatidylcholines

BACKGROUND

Ether-linked phosphatidylcholines (PCs) include both plasmanyl and plasmenyl PCs, which contain an ether or a vinyl ether bond at the sn-1 linkage position, respectively. Profiling and quantifying ether PCs with accurate structural information is challenging because of the common presence of isomeric and isobaric species in a lipidome.

RESULTS

In the present study, radical directed dissociation (RDD) from collision-induced dissociation (CID) of the bicarbonate anion adduct of ether PCs has been investigated to differentiate and relatively quantify ether PCs. Alkyl- and alkenyl- PCs give diagnostic characteristic fragment patterns that enable their confident identification and isomer differentiation. Additionally, the sn-position specific product ions have proven effective for relative quantitation among isomers in ether PCs and their isobaric PC species. Using this methodology, we successfully identified a total of 30 PC-O species, 21 PC-P species at the chain composition level, and 22 species of isobaric PC at the sn-position level in the human plasma lipid extract. The quantitative analysis revealed that ether PCs with a 20:4 fatty acyl chain are relatively more abundant in human plasma. Finally, the profile of ether PCs in type 2 diabetic (T2D) groups compared to normal control groups revealed a significant decrease in PC-O 18:1/20:5. We also found it is the PC species containing a 17-carbon fatty acyl chain, rather than their isobaric ether PCs, that shows a decreasing trend in the T2D groups.

SIGNIFICANCE

ether-linked PCs are firstly investigated by RDD mass spectrometry.

Identification of the Active EPA/AA-Binding Ether-Type Phosphatidylcholine Derived from the Starfish Patiria pectinifera for C2C12 Myotube Growth

Concerns about nutritional approaches for promoting skeletal muscle mass and function have increased. This study assessed the effects of starfish-derived glycerophospholipids (PLs) (SPL), characterized by unique ether-linked subclasses, alkylacyl (Alk)- and alkenylacyl (Pls)-PL, on skeletal muscle function, focusing on myotube formation in C2C12 myoblasts. SPL was prepared via chloroform/methanol extraction from Patiria pectinifera, followed by silica gel chromatography fractionation. Myoblasts were induced to differentiate with or without SPL treatment. On day 7 of differentiation, 50 μg/mL of SPL treatment increased myotube diameter. The phosphatidylcholine (PC) fraction (SPC) also enhanced myotube growth at 30 μg/mL. LC-MS/MS analysis indicated the most abundant PC molecular species in SPC were Alk- and Pls-PC with eicosapentaenoic acid and arachidonic acid. Treatment with 1-O-hexadecyl-2-arachidonoyl-PC, 1-1(Z)-hexadecenyl-2-arachidonoyl-PC or 1-O-hexadecyl-2-eicosapentaenoyl-PC increased myotube diameter and myokine Il-15 mRNA expression. These results demonstrate a novel functionality of SPC and highlight the role of ether-type PC molecules in muscle function.

Tandem Mass Spectrometry in Untargeted Lipidomics: A Case Study of Peripheral Blood Mononuclear Cells

Peripheral blood mononuclear cells (PBMCs), including lymphocytes, are important components of the human immune system. These cells contain a diverse array of lipids, primarily glycerophospholipids (GPs) and sphingolipids (SPs), which play essential roles in cellular structure, signaling, and programmed cell death. This study presents a detailed analysis of GP and SP profiles in human PBMC samples using tandem mass spectrometry (MS/MS). Hydrophilic interaction liquid chromatography (HILIC) and electrospray ionization (ESI) coupled with linear ion-trap MS/MS were employed to investigate the diagnostic fragmentation patterns that aided in determining regiochemistry in complex lipid extracts. Specifically, the study explored the fragmentation patterns of various lipid species, including phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), their plasmalogen and lyso forms, phosphatidylserines (PSs), phosphatidylinositols (PIs), phosphatidylglycerols (PGs), sphingomyelins (SMs), and dihexosylceramides (Hex2Cer). Our comprehensive analysis led to the characterization of over 200 distinct lipid species, significantly expanding our understanding of PBMC lipidome complexity. A freely available spreadsheet tool for simulating MS/MS spectra of GPs is provided, enhancing the accessibility and reproducibility of this research. This study advances our knowledge of PBMC lipidomes and establishes a robust analytical framework for future investigations in lipidomics.

Apo E protein and related markers show the prognosis of stress urinary incontinence rats treated with modified Buzhong Yiqi Decoction

Stress urinary incontinence (SUI) is a common disease that seriously affects the quality of life of patients. In recent years, studies have shown that apolipoprotein E (ApoE) plays a role in neuroprotection and repair, but its specific role in SUI remains unclear. The aim of this study was to investigate the effect of macromolecular protein ApoE related markers on the prognosis of rats with SUI treated by modified Buzhong Yiqi Decoction (MBZYQD), in order to provide a new target for the treatment of SUI. Healthy rats were selected to establish a SUI model and divided into groups. The levels of ApoE related metabolites in blood of rats were detected by Metabolomics analysis and Lipidomics analysis. The urine leakage point pressure (LPP) were compared in each group, and the therapeutic effect of MBZYQD was evaluated. Compared with the model group, the LPP of rats in MBZYQD supplemented group was significantly higher. Compared with the control group, the LPP of MBZYQD was not statistically significant before and after treatment. The macromolecular protein ApoE may plays a key role in the treatment of SUI by MBZYQD, which can improve symptoms by regulating lipid metabolism repair.

B cell expression of the enzyme PexRAP, an intermediary in ether lipid biosynthesis, promotes antibody responses and germinal center size

The qualities of antibody (Ab) responses provided by B lymphocytes and their plasma cell (PC) descendants are crucial facets of responses to vaccines and microbes. Metabolic processes and products regulate aspects of B cell proliferation and differentiation into germinal center (GC) and PC states as well as Ab diversification. However, there is little information about lymphoid cell-intrinsic functions of enzymes that mediate ether lipid biosynthesis, including a major class of membrane phospholipids. Imaging mass spectrometry (IMS) results had indicated that concentrations of a number of these phospholipids were substantially enhanced in GC compared to the background average in spleens. However, it was not clear if biosynthesis in B cells was a basis for this finding, or whether such cell-intrinsic biosynthesis contributes to B cell physiology or Ab responses. Ether lipid biosynthesis can involve the enzyme PexRAP, the product of the Dhrs7b gene. Using combinations of IMS and immunization experiments in mouse models with inducible Dhrs7b loss-of-function, we now show that B lineage-intrinsic expression of PexRAP promotes the magnitude and affinity maturation of a serological response. Moreover, the data revealed a Dhrs7b -dependent increase in ether phospholipids in primary follicles with a more prominent increase in GC. Mechanistically, PexRAP impacted B cell proliferation via enhanced survival associated with controlling levels of ROS and membrane peroxidation. These findings reveal a vital role of this peroxisomal enzyme in B cell homeostasis and the physiology of humoral immunity.

Uncovering lipid dynamics in Staphylococcus aureus osteomyelitis using multimodal imaging mass spectrometry

Osteomyelitis occurs when Staphylococcus aureus invades the bone microenvironment, resulting in a bone marrow abscess with a spatially defined architecture of cells and biomolecules. Imaging mass spectrometry and microscopy are tools that can be employed to interrogate the lipidome of S. aureus-infected murine femurs and reveal metabolic and signaling consequences of infection. Here, nearly 250 lipids were spatially mapped to healthy and infection-associated morphological features throughout the femur, establishing composition profiles for tissue types. Ether lipids and arachidonoyl lipids were altered between cells and tissue structures in abscesses, suggesting their roles in abscess formation and inflammatory signaling. Sterols, triglycerides, bis(monoacylglycero)phosphates, and gangliosides possessed ring-like distributions throughout the abscess, suggesting a hypothesized dysregulation of lipid metabolism in a population of cells that cannot be discerned with traditional microscopy. These data provide insight into the signaling function and metabolism of cells in the fibrotic border of abscesses, likely characteristic of lipid-laden macrophages.

Mass spectrometry unveils heat-induced changes in yolk oxylipins and key lipid molecules during home cooking

INTRODUCTION

Oxylipins, as a widespread class of metabolic markers following oxidative stress, and several studies have reported dietary regulation of lipid metabolism. However, there is a lack of investigation of dietary oxylipins, especially cooking-induced changes in food lipid oxidation.

OBJECTIVES

Investigated the effects of cooking methods and lipid profiles on polyunsaturated fatty acids derived oxylipins generation within egg yolks.

METHODS

The lipid profile of egg yolk was determined by UPLC-QTOF-MS/MS, oxylipins were detected by HPLC-QTRAP-MS/MS, while the total fatty acid content was quantified by GC-FID. Random Forest (RF) and Partial Least Squares (PLS) regression models were employed to explore the association between oxidized lipids and key lipid species.

RESULTS

Heating reduced egg yolk docosahexaenoic acid (DHA) content, and no consistent trends for arachidonic acid (AA), linoleic acid (LA), and linolenic acid (ALA). Yolk lipid composition affected triacylglycerol (TG), phosphatidylethanolamine (PE), and LA-monoepoxide contents after cooking. 9- and 13-HODE (hydroxyoctadecadienoic acid), 9,10,13-TriHOME (trihydroxyoctadecenoic acid), 9,10- and 12,13-EpOME (epoxyoctadecenoic acid), 9,10- and 12,13-DiHOME (dihydroxyoctadecenoic acid), 5-HETE (hydroxyeicosatetraenoic acid), and 4-HDHA (hydroxydocosahexaenoic acid) were the prevalent oxylipins with high concentrations, accounting for 1.08 %-29.58 % of the total content of 29 oxylipins. Steaming resulted in a 1.9-fold increase in oxylipin concentrations in yolks compared to raw yolks, and boiling with or without shells (poaching) resulted in a 1.30- to 1.76-fold increase in oxylipin concentrations. In contrast, pan-fried yolks exhibited the lowest and least variable levels of total oxylipins, while still retaining some epoxides, including epoxyeicosatrienoic acid (EET) and EpOME. Utilizing big data analysis, we mapped the oxylipin network in both ordinary and DHA-enriched egg yolks, revealing a strong correlation between cooking-induced oxylipin production and variations in 24 lipid species.

CONCLUSION

Revealed the potential mechanisms and key lipid molecules for heating-induced oxylipin production of yolk through lipidomics and big data analysis.

Longitudinal lipidomic profiles of left ventricular mass and left ventricular hypertrophy in American Indians

BACKGROUNDLeft ventricular hypertrophy (LVH) and dyslipidemia are strong, independent predictors for cardiovascular disease, but their relationship is less well studied. A longitudinal lipidomic profiling of left ventricular mass (LVM) and LVH is still lacking.METHODSUsing liquid chromatography-mass spectrometry (LC-MS), we repeatedly measured 1,542 lipids from 1,755 unique American Indians attending 2 exams (mean, 5 years apart). Cross-sectional associations of individual lipid species with LVM index (LVMI) were examined by generalized estimating equation (GEE), followed by replication in an independent biracial cohort (65% White, 35% Black). Baseline plasma lipids associated with LVH risk beyond traditional risk factors were identified by logistic GEE model in American Indians. Longitudinal associations between changes in lipids and changes in LVMI were examined by GEE, adjusting for baseline lipids, baseline LVMI, and covariates.RESULTSMultiple lipid species were significantly associated with LVMI or the risk of LVH in American Indians. Some lipids were confirmed in Black and White individuals. Moreover, some LVH-related lipids were inversely associated with risk of coronary heart disease (CHD). Longitudinal changes in several lipid species were significantly associated with changes in LVMI.CONCLUSIONAltered fasting plasma lipidome and its longitudinal change over time were significantly associated with LVMI and risk for LVH in American Indians. Our results offer insight into the role of individual lipid species in LV remodeling and risk of LVH, independent of known risk factors.FUNDINGThis study was supported by the NIH grant (R01DK107532). The Strong Heart Study has been funded in whole or in part with federal funds from the National Heart, Lung, and Blood Institute, NIH, Department of Health and Human Services, under contract nos. 75N92019D00027, 75N92019D00028, 75N92019D00029, and 75N92019D00030.

Effects of Perfluorinated Alkyl Substances (PFAS) on Amphibian Body and Liver Conditions: Is Lipid Metabolism Being Perturbed throughout Metamorphosis?

Per- and polyfluoroalkyl substances (PFAS) may interact with peroxisome proliferator activated receptors (PPARs) and alter lipid homeostasis. Using Xenopus laevis, we investigated the effect of PFAS on (a) lipid homeostasis and whether this correlated to changes in body and hepatic condition; (b) the expression of hepatic genes regulated by PPAR; and (c) the hepatic lipidome. We chronically exposed tadpoles to 0.5 µg/L of either PFOS, PFHxS, PFOA, PFHxA, a binary mixture of PFOS and PFHxS (0.5 µg/L of each), or a control, from NF stage 52 through metamorphic climax. Growth, development, and survival were not affected, but we detected a sex-specific decrease in body condition at NF 66 (6.8%) and in hepatic condition (16.6%) across metamorphic climax for male tadpoles exposed to PFOS. We observed weak evidence for the transient downregulation of apolipoprotein-V (apoa5) at NF 62 in tadpoles exposed to PFHxA. Acyl-CoA oxidase 1 (acox1) was downregulated only in males exposed to PFHxS (Ln(Fold Change) = -0.54). We detected PFAS-specific downregulation of structural glycerophospholipids, while semi-quantitative profiling detected the upregulation in numerous glycerophospholipids, sphingomyelins, and diglycerides. Overall, our findings indicate that PFAS can induce sex-specific effects that change across larval development and metamorphosis. We demonstrate that PFAS alter lipid metabolism at environmentally relevant concentrations through divergent mechanisms that may not be related to PPARs, with an absence of effects on body condition, demonstrating the need for more molecular studies to elucidate mechanisms of PFAS-induced lipid dysregulation in amphibians and in other taxa.

Role and Function of Peroxisomes in Neuroinflammation

Peroxisomes are organelles involved in many cellular metabolic functions, including the degradation of very-long-chain fatty acids (VLCFAs; C ≥ 22), the initiation of ether-phospholipid synthesis, and the metabolism of reactive oxygen species. All of these processes are essential for the maintenance of cellular lipid and redox homeostasis, and their perturbation can trigger inflammatory response in immune cells, including in the central nervous system (CNS) resident microglia and astrocytes. Consistently, peroxisomal disorders, a group of congenital diseases caused by a block in peroxisomal biogenesis or the impairment of one of the peroxisomal enzymes, are associated with neuroinflammation. Peroxisomal function is also dysregulated in many neurodegenerative diseases and during brain aging, both of which are associated with neuroinflammation. This suggests that deciphering the role of peroxisomes in neuroinflammation may be important for understanding both congenital and age-related brain dysfunction. In this review, we discuss the current advances in understanding the role and function of peroxisomes in neuroinflammation.

Peroxisomal homeostasis in metabolic diseases and its implication in ferroptosis

Peroxisomes are dynamic organelles involved in various cellular processes, including lipid metabolism, redox homeostasis, and intracellular metabolite transfer. Accumulating evidence suggests that peroxisomal homeostasis plays a crucial role in human health and disease, particularly in metabolic disorders and ferroptosis. The abundance and function of peroxisomes are regulated by a complex interplay between biogenesis and degradation pathways, involving peroxins, membrane proteins, and pexophagy. Peroxisome-dependent lipid metabolism, especially the synthesis of ether-linked phospholipids, has been implicated in modulating cellular susceptibility to ferroptosis, a newly discovered form of iron-dependent cell death. This review discusses the current understanding of peroxisome homeostasis, its roles in redox regulation and lipid metabolism, and its implications in human diseases. We also summarize the main mechanisms of ferroptosis and highlight recent discoveries on how peroxisome-dependent metabolism and signaling influence ferroptosis sensitivity. A better understanding of the interplay between peroxisomal homeostasis and ferroptosis may provide new insights into disease pathogenesis and reveal novel therapeutic strategies for peroxisome-related metabolic disorders and ferroptosis-associated diseases.

Interorganelle phospholipid communication, a house not so divided

The presence of membrane-bound organelles with specific functions is one of the main hallmarks of eukaryotic cells. Organelle membranes are composed of specific lipids that govern their function and interorganelle communication. Discoveries in cell biology using imaging and omic technologies have revealed the mechanisms that drive membrane remodeling, organelle contact sites, and metabolite exchange. The interplay between multiple organelles and their interdependence is emerging as the next frontier for discovery using 3D reconstruction of volume electron microscopy (vEM) datasets. We discuss recent findings on the links between organelles that underlie common functions and cellular pathways. Specifically, we focus on the metabolism of ether glycerophospholipids that mediate organelle dynamics and their communication with each other, and the new imaging techniques that are powering these discoveries.

Redox system and ROS-related disorders in peroxisomes

Peroxisomes are essential organelles that help mitigate the oxidative damage caused by reactive oxygen species (ROS) through their antioxidant systems. They perform functions such as α-oxidation, β-oxidation, and the synthesis of cholesterol and ether phospholipids. During the breakdown of specific metabolites, peroxisomes generate ROS as byproducts, which can either be neutralized or contribute to oxidative stress. The relationship between peroxisomal metabolism and ROS-related disorders, including neurodegenerative diseases and cancers, has been studied for decades; however, the exact mechanisms remain unclear. Our review will provide recent insights into the peroxisomal redox system and its association with oxidative stress-related diseases.

Synthesis of Plasmalogen Derivatives with Unnatural Fatty Acids as Substrates for Ferroptosis Induction

Lipid peroxidation, the key step in the ferroptosis process, requires the oxidation of the double bonds of phospholipids in cellular membrane structures. Current research on ferroptosis mechanisms and new drug development has focused on naturally occurring phospholipids with internal double bonds. However, whether unnatural terminal double bonds can be involved in ferroptosis remains to be elucidated. In this study, we introduced terminal double bonds at the sn-2 position of phospholipids (Terminal Olefin Fatty Acids, TOFA) and discovered that these artificial phospholipids can kill cells alone, without ferroptosis inducers, and can be inhibited only by some ferroptosis inhibitors, such as ferrostatin-1, liproxstatin-1, alpha-tocopherol, but not deferoxamine mesylate. Our results reveal that phospholipids with terminal double bonds can participate in ferroptosis through an atypical mechanism. Moreover, further mechanistic studies could confirm that controlling the double bond position could be useful to maneuver ferroptosis and develop new drugs.

Neuronal lipid droplets play a conserved and sex-biased role in maintaining whole-body energy homeostasis

Lipids are essential for neuron development and physiology. Yet, the central hubs that coordinate lipid supply and demand in neurons remain unclear. Here, we combine invertebrate and vertebrate models to establish the presence and functional significance of neuronal lipid droplets (LD) in vivo. We find that LD are normally present in neurons in a non-uniform distribution across the brain, and demonstrate triglyceride metabolism enzymes and lipid droplet-associated proteins control neuronal LD formation through both canonical and recently-discovered pathways. Appropriate LD regulation in neurons has conserved and male-biased effects on whole-body energy homeostasis across flies and mice, specifically neurons that couple environmental cues with energy homeostasis. Mechanistically, LD-derived lipids support neuron function by providing phospholipids to sustain mitochondrial and endoplasmic reticulum homeostasis. Together, our work identifies a conserved role for LD as the organelle that coordinates lipid management in neurons, with implications for our understanding of mechanisms that preserve neuronal lipid homeostasis and function in health and disease.

Edible insects as a novel source of lecithin: Extraction and lipid characterization of black soldier fly larvae and yellow mealworm

Edible insects with high fat and phosphorus content are a potential novel source of lecithin, however, studies on their minor lipids are limited. In this study, lecithin was extracted from black soldier fly larvae and yellow mealworm. Herein, the effects of lecithin extraction method, matrix and ultrasound pretreatment were explored based on the fatty acid composition and phospholipid profile with soy lecithin as a reference. The use of a wet matrix and ultrasound pretreatment increased the extraction efficiency of total PLs from both insects. Insect lecithin contained a considerable amount of sphingomyelin compared to soy lecithin. In insect lecithin, a total of 47 glycerophospholipid and sphingomyelin molecular species, as well as four molecular species of fatty acyl esters of hydroxy fatty acid, were detected. This study is the first comprehensive investigation of insects as a new source of lecithin with applications in food, cosmetics and in the pharmaceutical industry.

Mendelian randomization analysis reveals causal effects of blood lipidome on gestational diabetes mellitus

BACKGROUND

Observational studies have revealed associations between maternal lipid metabolites and gestational diabetes mellitus (GDM). However, whether these associations are causal remain uncertain.

OBJECTIVE

To evaluate the causal relationship between lipid metabolites and GDM.

METHODS

A two-sample Mendelian randomization (MR) analysis was performed based on summary statistics. Sensitivity analyses, validation analyses and reverse MR analyses were conducted to assess the robustness of the MR results. Additionally, a phenome-wide MR (Phe-MR) analysis was performed to evaluate potential side effects of the targeted lipid metabolites.

RESULTS

A total of 295 lipid metabolites were included in this study, 29 of them had three or more instrumental variables (IVs) suitable for sensitivity analyses. The ratio of triglycerides to phosphoglycerides (TG_by_PG) was identified as a potential causal biomarker for GDM (inverse variance weighted (IVW) estimate: odds ratio (OR) = 2.147, 95% confidential interval (95% CI) 1.415-3.257, P = 3.26e-4), which was confirmed by validation and reverse MR results. Two other lipid metabolites, palmitoyl sphingomyelin (d18:1/16:0) (PSM(d18:1/16:0)) (IVW estimate: OR = 0.747, 95% CI 0.583-0.956, P = 0.021) and triglycerides in very small very low-density lipoprotein (XS_VLDL_TG) (IVW estimate: OR = 2.948, 95% CI 1.197-5.215, P = 0.015), were identified as suggestive potential biomarkers for GDM using a conventional cut-off P-value of 0.05. Phe-MR results indicated that lowering TG_by_PG had detrimental effects on two diseases but advantageous effects on the other 13 diseases.

CONCLUSION

Genetically predicted elevated TG_by_PG are causally associated with an increased risk of GDM. Side-effect profiles indicate that TG_by_PG might be a target for GDM prevention, though caution is advised due to potential adverse effects on other conditions.

Environmental Temperature Variation Affects Brain Lipid Composition in Adult Zebrafish (Danio rerio)

This study delves deeper into the impact of environmental temperature variations on the nervous system in teleost fish. Previous research has demonstrated that exposing adult zebrafish (Danio rerio) to 18 °C and 34 °C for 4 or 21 days induces behavioural changes compared to fish kept at a control temperature of 26 °C, suggesting alterations in the nervous system. Subsequent studies revealed that these temperature conditions also modify brain protein expression, indicating potential neurotoxic effects. The primary aim of this work was to investigate the effects of prolonged exposure (21 days) to 18 °C or 34 °C on the brain lipidomes of adult zebrafish compared to a control temperature. Analysis of the brain lipidome highlighted significant alteration in the relative abundances of specific lipid molecules at 18 °C and 34 °C, confirming distinct effects induced by both tested temperatures. Exposure to 18 °C resulted in an increase in levels of phospholipids, such as phosphatidylethanolamine, alongside a general reduction in levels of sphingolipids, including sphingomyelin. Conversely, exposure to 34 °C produced more pronounced effects, with increases in levels of phosphatidylethanolamine and those of various sphingolipids such as ceramide, gangliosides, and sphingomyelin, alongside a reduction in levels of ether phospholipids, including lysophosphatidylethanolamine ether, phosphatidylethanolamine ether, and phosphatidylglycerol ether, as well as levels of glycolipids like monogalactosyldiacylglycerol. These results, when integrated with existing proteomic and behavioural data, offer new insights into the effects of thermal variations on the nervous system in teleost fish. Specifically, our proteomic and lipidomic findings suggest that elevated temperatures may disrupt mitochondrial function, increase neuronal susceptibility to oxidative stress and cytotoxicity, alter axonal myelination, impair nerve impulse transmission, hinder synapse function and neurotransmitter release, and potentially lead to increased neuronal death. These findings are particularly relevant in the fields of cell biology, neurobiology, and ecotoxicology, especially in the context of global warming.

Essential trace element and phosphatidylcholine remodeling: Implications for body composition and insulin resistance

BACKGROUND

Recent studies indicated that bioactive lipids of phosphatidylcholines (PCs) and lysophosphatidylcholines (LysoPCs) predict unhealthy metabolic phenotypes, but results remain inconsistent. To fill this knowledge gap, we investigated whether essential trace elements affect PC-Lyso PC remodeling pathways and the risk of insulin resistance (IR).

METHODS

Anthropometric and blood biochemical data (glucose, insulin, and lipoprotein-associated phospholipase A2 (Lp-PLA2)) were obtained from 99 adults. Blood essential/probably essential trace elements and lipid metabolites were respectively measured by inductively coupled plasma mass spectrometry (ICP-MS), and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS).

RESULT AND CONCLUSION

Except for LysoPC (O-18:0/0:0), an inverse V shape was observed between body weight and PC and LysoPC species. A Pearson correlation analysis showed that essential/probably-essential metals (Se, Cu, and Ni: r=-0.4∼-0.7) were negatively correlated with PC metabolites but positively correlated with LysoPC (O-18:0/0:0) (Se, Cu, and Ni: r=0.85-0.64). Quantile-g computation showed that one quantile increase in essential metals was associated with a 2.16-fold increase in serum Lp-PLA2 (β=2.16 (95 % confidence interval (CI): 0.34, 3.98), p=0.023), which are key enzymes involved in PC/Lyso PC metabolism. An interactive analysis showed that compared to those with the lowest levels (reference), individuals with the highest levels of serum PCs (pooled, M2) and the lowest essential/probably essential metals (M1) were associated with a healthier body composition and had a 76 % decreased risk of IR (odds ratio (OR)=0.24 (95 % CI: 0.06, 0.90), p<0.05). In contrast, increased exposure to LysoPC(O-18:0/0:0) (M2) and essential metals (M2) exhibited an 8.22-times highest risk of IR (OR= 8.22 (2.07, 32.57), p<0.05) as well as an altered body composition. In conclusion, overexposure to essential/probably essential trace elements may promote an unhealthy body weight and IR through modulating PC/LysoPC remodeling pathways.

Alterations to sphingolipid metabolism from antipsychotic administration in healthy volunteers are restored following the use of cannabidiol

Randomized clinical trials substantiate cannabidiol (CBD) as a next-generation antipsychotic, effective in alleviating positive and negative symptoms associated with psychosis, while minimising the adverse effects seen with established treatments. Although the mechanisms remain debated, CBD is known to induce drug-responsive changes in lipid-based retrograde neurotransmitters. Lipid aberrations are also frequently observed with antipsychotics, which may contribute to their efficacy or increase the risk of undesirables, including metabolic dysfunction, obesity and dyslipidaemia. Our study investigated CBD's impact following lipid responses triggered by interaction with second-generation antipsychotics (SGA) in a randomized phase I safety study. Untargeted mass spectrometry assessed the lipidomic profiles of human sera, collected from 38 healthy volunteers. Serum samples were obtained prior to commencement of any medication (t = 0), 3 days after consecutive administration of one of the five, placebo-controlled, treatment arms designed to achieve steady-state concentrations of each SGA (amisulpride, 150 mg/day; quetiapine, 300 mg/day; olanzapine 10 mg/day; risperidone, 3 mg/day), and after six successive days of SGA treatment combined with CBD (800 mg/day). Receiver operating characteristics (ROC) refined 3712 features to a putative list of 15 lipids significantly altered (AUC > 0.7), classified into sphingolipids (53 %), glycerolipids (27 %) and glycerophospholipids (20 %). Targeted mass spectrometry confirmed reduced sphingomyelin and ceramide levels with antipsychotics, which mapped along their catabolic pathway and were restored by CBD. These sphingolipids inversely correlated with body weight after olanzapine, quetiapine, and risperidone treatment, where CBD appears to have arrested or attenuated these effects. Herein, we propose CBD may alleviate aberrant sphingolipid metabolism and that further investigation into sphingolipids as markers for monitoring side effects of SGAs and efficacy of CBD is warranted.

A comparative lipid profile of four fish species: From muscle to industrial by-products based on RPLC-Q-TOF-MS/MS

Fish are crucial for the fishing industry and essential nutrient provision, including lipids. This study employed a high-throughput lipidomic approach to evaluate and contrast the lipid profiles of three marine fish species (P. crocea, S. fuscens, and C. saira) and one freshwater species (H. molitrix) across head, muscle, and viscera. Over 1000 molecular lipid species across 17 subclasses were identified. Notably, acylated monogalactosyldiacylglycerol (acMGDG) was detected for the first time in these species, with a high prevalence of saturated fatty acids (44.7 %-87.7 %). Glycerolipids (67.7 - 86.3 %) and PLs (10.7 - 31.8 %) were identified as the dominant lipid classes. Marine fish muscles displayed higher PL content than freshwater species, and P. crocea viscera contained over 30 % PLs of total lipids. In particular, ether phosphatidyl ethanolamine incorporated more DHA than ether phosphatidylcholine. The viscera of four fish species also exhibited a significant abundance of diacylglycerol (DG), indicating their potential as functional lipid sources. Multivariate analysis identified triglyceride (TG) (59:13), DG (16:1/22:5), and MGDG (16:0/18:2) as potential biomarkers for differentiating among fish anatomical parts. This study deepens the understanding of the nutritional values of these fish, providing guidance for consumer dietary choices and paving the way for transforming previously underutilized by-products into resources with high-value potential.

The lipid-metabolism enzyme ECI2 reduces neutrophil extracellular traps formation for colorectal cancer suppression

Abnormalities in ether lipid metabolism as well as the formation of neutrophil extracellular traps have recently been recognized as detrimental factors affecting tumorigenesis and progression. However, the role of abnormal ether lipid metabolism in colorectal cancer (CRC) evolution has not been reported. Here we show that the lipid metabolism-related gene enoyl-CoA δ-isomerase 2 (ECI2) plays a tumor-suppressor role in CRC and is negatively associated with poor prognosis in CRC patients. We mechanistically demonstrate that ECI2 reduces ether lipid-mediated Interleukin 8 (IL-8) expression leading to decreased neutrophil recruitment and neutrophil extracellular traps formation for colorectal cancer suppression. In particular, ECI2 inhibits ether lipid production in CRC cells by inhibiting the peroxisomal localization of alkylglycerone phosphate synthase (AGPS), the rate-limiting enzyme for ether lipid synthesis. These findings not only deepen our understanding of the role of metabolic reprogramming and neutrophil interactions in the progression of CRC, but also provide ideas for identifying potential diagnostic markers and therapeutic targets for CRC.

High-Fat Feeding Alters Circulating Triglyceride Composition: Roles of FFA Desaturation and ω-3 Fatty Acid Availability

Hypertriglyceridemia is a risk factor for type 2 diabetes and cardiovascular disease (CVD). Plasma triglycerides (TGs) are a key factor for assessing the risk of diabetes or CVD. However, previous lipidomics studies have demonstrated that not all TG molecules behave the same way. Individual TGs with different fatty acid compositions are regulated differentially under various conditions. In addition, distinct groups of TGs were identified to be associated with increased diabetes risk (TGs with lower carbon number [C#] and double-bond number [DB#]), or with decreased risk (TGs with higher C# and DB#). In this study, we examined the effects of high-fat feeding in rats on plasma lipid profiles with special attention to TG profiles. Wistar rats were maintained on either a low-fat (control) or high-fat diet (HFD) for 2 weeks. Plasma samples were obtained before and 2.5 h after a meal (n = 10 each) and subjected to lipidomics analyses. High-fat feeding significantly impacted circulating lipid profiles, with the most significant effects observed on TG profile. The effects of an HFD on individual TG species depended on DB# in their fatty acid chains; an HFD increased TGs with low DB#, associated with increased diabetes risk, but decreased TGs with high DB#, associated with decreased risk. These changes in TGs with an HFD were associated with decreased indices of hepatic stearoyl-CoA desaturase (SCD) activity, assessed from hepatic fatty acid profiles. Decreased SCD activity would reduce the conversion of saturated to monounsaturated fatty acids, contributing to the increases in saturated TGs or TGs with low DB#. In addition, an HFD selectively depleted ω-3 polyunsaturated fatty acids (PUFAs), contributing to the decreases in TGs with high DB#. Thus, an HFD had profound impacts on circulating TG profiles. Some of these changes were at least partly explained by decreased hepatic SCD activity and depleted ω-3 PUFA.

Tumor Lipid Signatures Are Descriptive of Acquisition of Therapy Resistance in an Endocrine-Related Breast Cancer Mouse Model

The lipid metabolism adaptations of estrogen and progesterone receptor-positive breast cancer tumors from a mouse syngeneic model are investigated in relation to differences across the transition from hormone-dependent (HD) to hormone-independent (HI) tumor growth and the acquisition of endocrine therapy (ET) resistance (HIR tumors). Results are articulated with reported polar metabolome results to complete a metabolic picture of the above transitions and suggest markers of tumor progression and aggressiveness. Untargeted nuclear magnetic resonance metabolomics was used to analyze tumor and mammary tissue lipid extracts. Tumor progression (HD-HI-HIR) was accompanied by increased nonesterified cholesterol forms and phospholipids (phosphatidylcholine, phosphatidylethanolamine, sphingomyelins, and plasmalogens) and decreased relative contents of triglycerides and fatty acids. Predominating fatty acids became shorter and more saturated on average. These results were consistent with gradually more activated cholesterol synthesis, β-oxidation, and phospholipid biosynthesis to sustain tumor growth, as well as an increase in cholesterol (possibly oxysterol) forms. Particular compound levels and ratios were identified as potential endocrine tumor HD-HI-HIR progression markers, supporting new hypotheses to explain acquired ET resistance.

Lipidomics Profiling Reveals Differential Alterations after FAS Inhibition in 3D Colon Cancer Cell Culture Models

Cancerous cells synthesize most of their lipids de novo to keep up with their rapid growth and proliferation. Fatty acid synthase (FAS) is a key enzyme in the lipogenesis pathway that is upregulated in many cancers and has gained popularity as a druggable target of interest for cancer treatment. The first FAS inhibitor discovered, cerulenin, initially showed promise for chemotherapeutic purposes until it was observed that it had adverse side effects in mice. TVB-2640 (Denifanstat) is part of the newer generation of inhibitors. With multiple generations of FAS inhibitors being developed, it is vital to understand their distinct molecular downstream effects to elucidate potential interactions in the clinic. Here, we profile the lipidome of two different colorectal cancer (CRC) spheroids treated with a generation 1 inhibitor (cerulenin) or a generation 2 inhibitor (TVB-2640). We observe that the cerulenin causes drastic changes to the spheroid morphology as well as alterations to the lipid droplets found within CRC spheroids. TVB-2640 causes higher abundances of polyunsaturated fatty acids (PUFAs) whereas cerulenin causes a decreased abundance of PUFAs. The increase in PUFAs in TVB-2640 exposed spheroids indicates it is causing cells to die via a ferroptotic mechanism rather than a conventional apoptotic or necrotic mechanism.

Membrane vectorial lipidomic features of coral host cells' plasma membrane and lipid profiles of their endosymbionts Cladocopium

The symbiotic relationships between coral animal host and autotrophic dinoflagellates are based on the mutual exchange and tight control of nutritional inputs supporting successful growth. The corals Sinularia heterospiculata and Acropora aspera were cultivated using a flow-through circulation system supplying seawater during cold and warm seasons of the year, then sorted into host cells and symbionts and subjected to phylogenetic, morphological, and advanced lipid analyses. Here we show, that the lipidomes of the dinoflagellates Cladocopium C1/C3 and acroporide-specific Cladocopium hosted by the corals, are determined by lipidomic features of different thermosensitivity and unique betaine- and phospholipid molecular species. Phosphatidylserines and ceramiaminoethylphosphonates are not detected in the symbionts and predominantly localized on the inner leaflet of the S. heterospiculata host plasma membrane. The transmembrane distribution of phosphatidylethanolamines of S. heterospiculata host changes during different seasons of the year, possibly contributing to mutualistic nutritional exchange across this membrane complex to provide the host with a secure adaptive mechanism and ecological benefits.