Bioactive Lipid Research Articles

Direct Binding Methods to Measure Receptor-Ligand Interactions.

G-protein-coupled receptors (GPCRs) contribute to numerous physiological processes via complex network mechanisms. While indirect signaling assays (Ca2+ mobilization, cAMP production, and GTPγS binding) have been useful in identifying and characterizing downstream signaling mechanisms of GPCRs, these methods lack measurements of direct binding affinities, kinetics, binding specificity, and selectivity that are important parameters in GPCR drug discovery. In comparison to existing direct methods that use radio- or fluorescent labels, label-free techniques can closely emulate the native interactions around binding partners. Surface plasmon resonance (SPR) is a label-free technique that utilizes the refractive index (RI) property and is applied widely in quantitative GPCR-ligand binding kinetics measurement including small molecules screening. However, purified GPCRs are further embedded in a synthetic lipid environment which is immobilized through different tags to the SPR sensor surface, resulting in a non-native environment. Here, we introduced a methodology that also uses the RI property to measure binding interactions in a label-free, immobilization-free arrangement. The free-solution technique is successfully applied in quantifying the interaction of bioactive lipids to cognate lipid GPCRs, which is not purified but rather present in near-native conditions, i.e., in milieu of other cytoplasmic lipids and proteins. To further consider the wide applicability of these free-solution approaches in biomolecular interaction research, additional applications on a variety of receptor-ligand pairs are imperative.

Understanding the modulations of glycero-lysophospholipids in an elastase-induced murine emphysema model

BackgroundIncreasing evidence indicates that bioactive lipid mediators are involved in chronic obstructive pulmonary disease (COPD) pathogenesis. Recently, glycero-lysophospholipids, such as lysophosphatidic acid (LysoPA) and lysophosphatidylserine (LysoPS), have been recognized as significant inflammation-related lipid mediators. However, their association with COPD remains unclear. MethodsWe used an elastase-induced murine emphysema model to analyze the levels of lysophospholipids and diacyl-phospholipids in the lungs. Additionally, we assessed the expression of LysoPS-related genes and published data on smokers. ResultsIn the early phase of an elastase-induced murine emphysema model, the levels of LysoPS and its precursor (phosphatidylserine [PS]) were significantly reduced, without significant modulations in other glycero-lysophospholipids. Additionally, there was an upregulation in the expression of lysoPS receptors, specifically GPR34, observed in the lungs of a cigarette smoke-exposed mouse model and the alveolar macrophages of human smokers. Elastase stimulation induces GPR34 expression in a human macrophage cell line in vitro. ConclusionsElastase-induced lung emphysema affects the LysoPS/PS-GPR34 axis, and cigarette smoking or elastase upregulates GPR34 expression in alveolar macrophages. This novel association may serve as a potential pharmacological target for COPD treatment.

Wide-scope targeted analysis of bioactive lipids in human plasma by LC/MS/MS

Quantitative information on blood metabolites can be used in developing advanced medical strategies such as early detection and prevention of disease. Monitoring bioactive lipids such as steroids, bile acids, and PUFA metabolites could be a valuable indicator of health status. However, a method for simultaneously measuring these bioactive lipids has not yet been developed. Here, we report a LC/MS/MS method that can simultaneously measure 144 bioactive lipids, including steroids, bile acids, and PUFA metabolites, from human plasma, and a sample preparation method for these targets. Protein removal by methanol precipitation and purification of bioactive lipids by solid-phase extraction improved the recovery of the targeted compounds in human plasma samples, demonstrating the importance of sample preparation methods for a wide range of bioactive lipid analyses. Using the developed method, we studied the plasma from healthy human volunteers and confirmed the presence of bioactive lipid molecules associated with sex differences and circadian rhythms. The developed method of bioactive lipid analysis can be applied to health monitoring and disease biomarker discovery in precision medicine.

Novel bioactive lipids enhanced HDL-mediated cholesterol efflux from macrophages through the ABCA1 receptor pathway

High-density lipoprotein (HDL) has traditionally been acknowledged as "good cholesterol" owing to its significant association with a decreased risk of atherosclerosis. This association is primarily attributed to HDL's direct involvement in cholesterol efflux capacity, which plays a pivotal role in reverse cholesterol transport. A novel active compound from Nannochloropsis microalgae termed lyso-DGTS, a lipid that contains EPA fatty acids, was previously isolated and found to increase paraoxonase 1 activity and enhance HDL-mediated cholesterol efflux and HDL-induced endothelial nitric oxide release. Here, the effect of different lyso-DGTS derivatives and analogs on HDL-mediated cholesterol efflux from macrophages was examined, and the mechanism was explored. Structure–activity relationships were established to characterize the essential lipid moieties responsible for HDL-mediated cholesterol efflux from macrophages. Lyso-DGTS, 1-carboxy-N-N-N-trimethyl-3-oleamidopropan-1-aminium, and lyso-platelet-activating factor increased HDL-mediated cholesterol efflux from macrophages dose-dependently, mainly via the ABCA1-mediated cholesterol efflux pathway. The effect of lyso-DGTS derivatives and analogs on the surface polarity of HDL was examined using the Laurdan generalized polarization (GP) assay. A reverse Pearson linear regression was obtained between Laurdan GP values and HDL-mediated cholesterol efflux. Because the incorporation of bioactive lipids into the surface phospholipid layer of HDL leads to a decrease in Laurdan GP, these bioactive lipids may induce lower phospholipid ordering and greater free space on the HDL particle surface, thereby enhancing apolipoprotein A1 binding to the ABCA1 receptor and improving ABCA1 cholesterol-mediated efflux. Our findings suggest a beneficial effect of lyso-DGTS and its bioactive lipid derivatives on increasing HDL-mediated cholesterol efflux activity from macrophages, which may impact atherosclerosis attenuation.

14,15-Dihydroxyeicosatrienoic acid, a soluble epoxide hydrolase metabolite in blood, is a predictor of anthracycline-induced cardiotoxicity – a hypothesis generating study

BackgroundEarly identification of patients susceptible to chemotherapy-induced cardiotoxicity could lead to targeted treatment to reduce cardiac dysfunction. Rats treated with doxorubicin (DOX), a chemotherapeutic agent, have increased cardiac expression of 14,15-dihydroxyeicosatrienoic acid (14,15-DHET), a bioactive lipid implicated in hypertension and coronary artery disease. However, the utility of 14,15-DHET as plasma biomarkers was not defined. The aim of this study is to investigate if levels of 14,15-DHET are an early blood biomarker to predict the subsequent occurrence of cardiotoxicity in cancer patients after chemotherapy.MethodsH9c2 rat cardiomyocytes were treated with DOX (1 μM) for 2 h and levels of 14,15-DHET in cell media was quantified at 2, 6 or 24 h in media after DOX treatment. Similarly, female Sprague–Dawley rats were treated with DOX for two weeks and levels of 14,15-DHET was assessed in plasma at 48 h and 2 weeks after DOX treatment. Changes in brain natriuretic peptide (BNP) mRNA, an early cardiac hypertrophy process, were determined in the H9c2 cells and rat cardiac tissue. Results were confirmed in human subjects by assessment of levels of 14,15-DHET in plasma of breast cancer patients before and after DOX treatment and left ventricular ejection fraction (LVEF), a clinical marker of cardiotoxicity.ResultsLevels of 14,15-DHET in cell media and rat plasma increased ~ 3-fold and was accompanied with increase in BNP mRNA in H9c2 cells and rat cardiac tissue after DOX treatment. In matched plasma samples from breast cancer patients, levels of 14,15-DHET were increased in patients that developed cardiotoxicity at 3 months before occurrence of LVEF decrease.ConclusionsTogether, these results indicate that levels of 14,15-DHET are elevated prior to major changes in cardiac structure and function after exposure to anthracyclines. Increased levels of 14,15-DHET in plasma may be an important clinical biomarker for early detection of anthracycline-induced cardiotoxicity in cancer patients.

Responses of the maize rhizosphere soil environment to drought-flood abrupt alternation stress.

Changes in the soil environment in the root zone will affect the growth, development and resistance of plants. The mechanism underlying the effect of drought and flood stress on rhizosphere bacterial diversity, soil metabolites and soil enzyme activity is not clear and needs further study. To analyze the dynamic changes in bacteria, metabolites and enzyme activities in the rhizosphere soil of maize under different drought-flood abrupt alternation (DFAA) stresses, the barrel test method was used to set up the 'sporadic light rain' to flooding (referring to trace rainfall to heavy rain) (DFAA1) group, 'continuous drought' to flooding (DFAA2) group and normal irrigation (CK) group from the jointing to the tassel flowering stage of maize. The results showed that Actinobacteria was the most dominant phylum in the two DFAA groups during the drought period and the rewatering period, and Proteobacteria was the most dominant phylum during the flooding period and the harvest period. The alpha diversity index of rhizosphere bacteria in the DFAA2 group during the flooding period was significantly lower than that in other stages, and the relative abundance of Chloroflexi was higher. The correlation analysis between the differential genera and soil metabolites of the two DFAA groups showed that the relative abundance of Paenibacillus in the DFAA1 group was higher during the drought period, and it was significantly positively correlated with the bioactive lipid metabolites. The differential SJA-15 bacterium was enriched in the DFAA2 group during the flooding period and were strongly correlated with biogenic amine metabolites. The relative abundances of Arthrobacter, Alphaproteobacteria and Brevibacillus in the DFAA2 group were higher compared with DFAA1 group from rewatering to harvest and were significantly positively correlated with hydrocarbon compounds and steroid hormone metabolites. The acid phosphatase activity of the DFAA1 group was significantly higher than that of the DFAA2 group during the flooding period. The study suggests that there is a yield compensation phenomenon in the conversion of 'continuous drought' to flooding compared with 'sporadic light rain', which is related to the improvement in the flooding tolerance of maize by the dominant bacteria Chloroflexi, bacterium SJA-15 and biogenic amine metabolites. These rhizosphere bacteria and soil metabolites may have the potential function of helping plants adapt to the DFAA environment. The study revealed the response of the maize rhizosphere soil environment to DFAA stress and provided new ideas for exploring the potential mechanism of crop yield compensation under DFAA.

Hepatic oxylipin profiles in mouse models of Wilson disease: New insights into early hepatic manifestations

Hepatic inflammation is commonly identified in Wilson disease (WD), a genetic disease of hepatic and brain copper accumulation. Copper accumulation is associated with increased oxidative stress and reactive oxygen species generation which may result in non-enzymatic oxidation of membrane-bound polyunsaturated fatty acids (PUFA). PUFA can be oxidized enzymatically via lipoxygenases (LOX), cyclooxygenases (COX), and cytochrome P450 monooxygenases (CYP). Products of PUFA oxidation are collectively known as oxylipins (OXL) and are bioactive lipids that modulate hepatic inflammation. We examined hepatic OXL profiles at early stages of WD in two mouse models, the toxic milk mouse from The Jackson Laboratory (tx-j) and the Atp7b knockout on a C57Bl/6 background (Atp7b−/−B6). Targeted lipidomic analysis performed by ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry showed that in both tx-j and Atp7b−/−B6 mice, hepatic OXL profiles were altered with higher thromboxane and prostaglandins levels. The levels of oxidative stress marker, 9-HETE were increased more markedly in tx-j mice. However, both genotypes showed upregulated transcript levels of many genes related to oxidative stress and inflammation. Both genotypes showed higher prostaglandins, thromboxin along with higher PUFA-derived alcohols, diols, and ketones with altered epoxides; the expression of Alox5 was upregulated and many CYP-related genes were dysregulated. Pathway analyses show dysregulation in arachidonic acid and linoleic acid metabolism characterizes mice with WD. Our findings indicate alterations in hepatic PUFA metabolism in early-stage WD and suggest the upregulation of both, non-enzymatic ROS-dependent and enzymatic PUFA oxidation, which could have implications for hepatic manifestations in WD and represent potential targets for future therapies.

Senescence-associated 13-HODE production promotes age-related liver steatosis by directly inhibiting catalase activity

Aging is a major risk factor for metabolic disorders. Polyunsaturated fatty acid-derived bioactive lipids play critical roles as signaling molecules in metabolic processes. Nonetheless, their effects on age-related liver steatosis remain unknown. Here we show that senescent liver cells induce liver steatosis in a paracrine manner. Linoleic acid-derived 9-hydroxy-octadecadienoic acid (9-HODE) and 13-HODE increase in middle-aged (12-month-old) and aged (20-month-old) male mouse livers and conditioned medium from senescent hepatocytes and macrophages. Arachidonate 15-lipoxygenase, an enzyme for 13-HODE and 9-HODE production, is upregulated in senescent cells. A 9-HODE and 13-HODE mixture induces liver steatosis and activates SREBP1. Furthermore, catalase (CAT) is a direct target of 13-HODE, and its activity is decreased by 13-HODE. CAT overexpression reduces 13-HODE-induced liver steatosis and protects male mice against age-related liver steatosis. Therefore, 13-HODE produced by senescent hepatocytes and macrophages activates SREBP1 by directly inhibiting CAT activity and promotes liver steatosis.

Emerging mechanisms by which endocannabinoids and their derivatives modulate bacterial populations within the gut microbiome.

Bioactive lipids such as endocannabinoids serve as important modulators of host health and disease through their effects on various host functions including central metabolism, gut physiology, and immunity. Furthermore, changes to the gut microbiome caused by external factors such as diet or by disease development have been associated with altered endocannabinoid tone and disease outcomes. These observations suggest the existence of reciprocal relationships between host lipid signaling networks and bacterial populations that reside within the gut. Indeed, endocannabinoids and their congeners such as N-acylethanolamides have been recently shown to alter bacterial growth, functions, physiology, and behaviors, therefore introducing putative mechanisms by which these bioactive lipids directly modulate the gut microbiome. Moreover, these potential interactions add another layer of complexity to the regulation of host health and disease pathogenesis that may be mediated by endocannabinoids and their derivatives. This mini review will summarize recent literature that exemplifies how N-acylethanolamides and monoacylglycerols including endocannabinoids can impact bacterial populations in vitro and within the gut microbiome. We also highlight exciting preclinical studies that have engineered gut bacteria to synthesize host N-acylethanolamides or their precursors as potential strategies to treat diseases that are in part driven by aberrant lipid signaling, including obesity and inflammatory bowel diseases.

Crosstalk between neutrophil extracellular traps and immune regulation: insights into pathobiology and therapeutic implications of transfusion-related acute lung injury.

Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-associated death, occurring during or within 6 hours after transfusion. Reports indicate that TRALI can be categorized as having or lacking acute respiratory distress syndrome (ARDS) risk factors. There are two types of TRALI in terms of its pathogenesis: antibody-mediated and non-antibody-mediated. The key initiation steps involve the priming and activation of neutrophils, with neutrophil extracellular traps (NETs) being established as effector molecules formed by activated neutrophils in response to various stimuli. These NETs contribute to the production and release of reactive oxygen species (ROS) and participate in the destruction of pulmonary vascular endothelial cells. The significant role of NETs in TRALI is well recognized, offering a potential pathway for TRALI treatment. Moreover, platelets, macrophages, endothelial cells, and complements have been identified as promoters of NET formation. Concurrently, studies have demonstrated that the storage of platelets and concentrated red blood cells (RBC) can induce TRALI through bioactive lipids. In this article, recent clinical and pre-clinical studies on the pathophysiology and pathogenesis of TRALI are reviewed to further illuminate the mechanism through which NETs induce TRALI. This review aims to propose new therapeutic strategies for TRALI, with the hope of effectively improving its poor prognosis.

The accumulation of sphingosine kinase 2 disrupts the DNA damage response and promotes resistance to genotoxic agents

There is a known correlation between cancer and changes in sphingolipids, specifically the production of sphingosine-1-phosphate (S1P) by sphingosine kinases 1 and 2 (SPHK1/SPHK2). However, a potential relationship between bioactive lipid molecules, SPHK, and the response to DNA damage is unknown. We aimed to evaluate the response of oral keratinocytes and head and neck cancer cell lines with SPHK2/S1P alterations to DNA damage. This assessment is intended to establish a link between these alterations and tumorigenesis as well as resistance to therapy. SPHK2 overexpression in oral squamous cells promoted evasion of apoptosis and cell cycle control, which increased the resistance to genotoxic agents (chemical and physical). Cells that have SPHK2 overexpression are more prone to DNA damage, which allows those damaged cells to survive and multiply. This is associated with a decrease in overall DNA methylation. These discoveries help to clarify the connection between SPHK2 and the response to DNA damage, as well as its capacity to aid in the resistance against genotoxic agents, including those used in cancer treatment.

Therapeutic potential and pharmacological significance of extracellular vesicles derived from traditional medicinal plants.

Medicinal plants are the primary sources for the discovery of novel medicines and the basis of ethnopharmacological research. While existing studies mainly focus on the chemical compounds, there is little research about the functions of other contents in medicinal plants. Extracellular vesicles (EVs) are functionally active, nanoscale, membrane-bound vesicles secreted by almost all eukaryotic cells. Intriguingly, plant-derived extracellular vesicles (PDEVs) also have been implicated to play an important role in therapeutic application. PDEVs were reported to have physical and chemical properties similar to mammalian EVs, which are rich in lipids, proteins, nucleic acids, and pharmacologically active compounds. Besides these properties, PDEVs also exhibit unique advantages, especially intrinsic bioactivity, high stability, and easy absorption. PDEVs were found to be transferred into recipient cells and significantly affect their biological process involved in many diseases, such as inflammation and tumors. PDEVs also could offer unique morphological and compositional characteristics as natural nanocarriers by innately shuttling bioactive lipids, RNA, proteins, and other pharmacologically active substances. In addition, PDEVs could effectively encapsulate hydrophobic and hydrophilic chemicals, remain stable, and cross stringent biological barriers. Thus, this study focuses on the pharmacological action and mechanisms of PDEVs in therapeutic applications. We also systemically deal with facets of PDEVs, ranging from their isolation to composition, biological functions, and biotherapeutic roles. Efforts are also made to elucidate recent advances in re-engineering PDEVs applied as stable, effective, and non-immunogenic therapeutic applications to meet the ever-stringent demands. Considering its unique advantages, these studies not only provide relevant scientific evidence on therapeutic applications but could also replenish and inherit precious cultural heritage.

Oxysterols in Infectious Diseases.

Oxysterols have emerged as important bioactive lipids in the immune response to infectious diseases. This chapter discusses our current knowledge of oxysterols and their receptors in bacterial and viral infections of the respiratory and gastrointestinal tracts. Oxysterols are produced in response to infections and have multiple roles including chemotaxis of immune cells to the site of infection and regulation of inflammation. Some oxysterols have been shown to possess antiviral or antibacterial activity.Lastly, we delve into the emerging mechanisms of action of oxysterols. Oxysterols can enhance host cell resistance via reduction of membrane accessible cholesterol, modulate membrane immune signalling, and impact inflammasome activation and efferocytosis.

Boosting the therapeutic potential of cell secretome against osteoarthritis: Comparison of cytokine-based priming strategies

The secretome, or conditioned medium (CM), from Mesenchymal Stem/stromal Cells (MSCs) has recently emerged as a promising cell-free therapeutic against osteoarthritis (OA), capable of promoting cartilage regeneration and immunoregulation. Priming MSCs with 10 ng/ml tumor necrosis factor α (TNFα) and/or 10 ng/ml interleukin 1β (IL-1β) aims at mimicking the pathological milieu of OA joints in order to target their secretion towards a pathology-tailored phenotype. Here we compare the composition of the CM obtained after 24 or 72 h from untreated and cytokine-treated adipose-derived MSCs (ASCs). The 72-hour double-primed CM presents a higher total protein yield, a larger number of extracellular vesicles, and a greater concentration of bioactive lipids, in particular sphingolipids, fatty acids, and eicosanoids. Moreover, the levels of several factors involved in immunomodulation and regeneration, such as TGF-β1, PGE2, and CCL-2, are strongly upregulated. Additionally, the differential profiling of 80 bioactive molecules indicates that primed CM is enriched in immune cell chemotaxis and migration factors. Our results indicate that pre-conditioning ASCs with inflammatory cytokines can modulate the composition of their CM, promoting the release of factors with recognized anti-inflammatory, chondroprotective, and immunoregulatory properties.

Biological Role of Extracellular Vesicles in Myeloid Neoplasms: A Systematic Review of the Current Literature

Background and aim: Extracellular vesicles (EVs) are lipid-bilayer membrane vesicles secreted by a variety of cells that carry bioactive molecules like proteins, lipids and nucleic acids. They are of increasing interest as they play an important biological role in cancer by a multitude of cell-extrinsic and cell-intrinsic mechanisms. However, the investigations of their biology in myeloid malignancies has not been systematically reviewed so far. Therefore, the aim of this review was to summarize the currently published literature in the field and provide an overview of their potential clinical applications. Method: We performed a systematic literature research with defined search strings in the Embase, Medline and PubMed Central databases and used a standardized data-extraction form to collect all relevant information. Results: 63 of 1529 studies met the inclusion/exclusion criteria and could be assigned to seven main investigational categories ( A). They comprised studies on their effect on i) prothrombotic activity (n=13), ii) tumor-microenvironment (n=14), iii) malignant transformation (n=5), iv) tumor progression (n=4), v) chemotherapy-resistance (n=5) as well as their use as vi) biomarkers (n=14) and vii) pharmacotherapeutic carriers (n=3) ( B). The most relevant biological mechanism is the transfer of microRNA (miRNA) by EVs from different clonal and non-clonal cells, which target the microenvironment, vascular system, as well as immune cells. All mechanisms identified in our review were assigned to one of the seven main categories and the most relevant are summarized in C: i) Prothrombotic activity: Leukaemic cells shed prothrombotic EVs containing tissue-factor (TF) and anionic phosphatidylserine (PS), which facilitate the recruitment of coagulation factors and a pro-coagulant state ( Zannoni, 2019). Reduction of EVs from platelets and leucocytes after chemotherapy attenuates this pro-coagulant state ( Van Aalderen, 2011). ii) Tumor microenvironment: EVs derived from MDS cells can disrupt the osteolineage differentiation of bone marrow mesenchymal stromal cells (BM-MSCs) and impair hematopoiesis ( Hayashi, 2022). iii) Malignant transformation: EVs containing BCR-ABL1 mRNA are integrated into BM-MSCs, which induce BCR-ABL1 expression and secretion of TGF-β1 leading to enhanced proliferation of BM-MSCs ( Fu, 2017). iv) Tumor progression: EVs derived from leukemic cells promote tumor progression by reducing apoptosis and tumor immune-surveillance. v) Chemotherapy resistance: AML-cells expel PEGylated liposomal doxorubicin (PLD) through EVs thus increasing their resistance ( Hekmatirad, 2021). vi) Disease biomarkers: AML patients at diagnosis have a higher number of EVs carrying the myeloblast markers CD34, CD117, CD33 and HLA-DR than AML patients in remission or healthy controls ( Tzoran, 2015). Based on differential abundancy and the content of proteins, lipids and nucleid acids EVs may be suitable as biomarkers for diagnosis, prognosis, and disease monitoring. vii) Pharmacotherapeutic role: Cytotoxic T-lymphocytes are more effective in killing the parental leukaemic cells after being exposed to their cell-derived EVs. The mechanism is related to leukemia antigen presentation on EVs to dendritic cells (DCs) using ICAM1 and Hsp70 ( Shen C, 2011). Finally, EVs can be used as carriers for bioactive compounds and may expand their potential use for cell-type specific delivery of drugs. Conclusions: EVs open the window for the future investigation of novel pathophysiological mechanisms that will improve our understanding of their role in the biology of myeloid malignancies, Moreover, they hold promise as potential biomarkers and drug carriers for cell-type specific treatment

Loss of 12-Lipoxygenase Improves the Post-Transfusion Function of Stored Platelets

Objective Platelets for transfusion are stored for 5-7 days. During storage, platelets undergo numerous detrimental functional changes. Previous studies have shown that HETE levels in the storage bag negatively correlate with platelet performance in vivo suggesting that the dysregulation of bioactive lipid mediators may contribute to the storage lesion. In the current study, we sought to understand how genetic deletion and pharmacologic inhibition of 12-lipoxygenase (12-LOX) affects platelets during storage and after transfusion. Approach and Results Platelets from12-LOX+/+ (wild-type [WT]) and 12-LOX-/- mice were stored for 24 and 48 hours and profiled using LC-MS/MS-MRM. Polyunsaturated fatty acids increased significantly in stored platelets from 12-LOX-/- mice, while oxylipin concentrations were significantly higher in WT platelets. Baseline αIIbβ 3 integrin activation was significantly lower before and after 24 hours of storage in 12-LOX-/- platelets than in WT platelets. Surprisingly, after transfusion to thrombocytopenic mice, we observed significantly more baseline αIIbβ3 integrin activation in 12-LOX-/- platelets than in WT platelets. Stored platelets from 12-LOX-/- mice occluded vessels significantly faster than stored WT platelets in thrombocytopenic recipients challenged with a FeCl 3-induced carotid artery injury. In hemostasis models, significantly more stored 12-LOX-/- than WT platelets accumulated at the site of venous injury leading to reduced blood loss. Inhibition of cyclooxygenase-1 (COX-1) with acetylsalicylic acid abrogated both increased integrin activation and thromboxane generation in stored 12-LOX-/- platelets, highlighting a critical role of this pathway for improved post-transfusion function. Consistent with our mouse studies, human platelets stored with the 12-LOX inhibitor, VLX-1005, showed increased integrin activation compared to vehicle-treated platelets upon transfusion in NOD/SCID mice. Conclusion Deleting 12-LOX improves the post-transfusion function of stored murine and human platelets by increasing thromboxane generation through a COX-1-dependent mechanism. Future studies should determine the feasibility and safety of 12-LOX-inhibited platelets transfused to humans.

Development of a functional dairy snack containing oleoylethanolamide that reduces food intake in normal-weight and obese minipigs

Oleoylethanolamide (OEA) is a safe bioactive lipid that demonstrated strong anorexigenic properties in preclinical and clinical models. In order to evaluate the importance of OEA delivery kinetic on its anorectic properties, we developed OEA-containing dairy snacks with either a liquid or a semi-solid form. The OEA+ liquid snack, but not the semi-solid one, reduced by 14 and 18 % the amount of feed eaten by normal-weight and obese minipigs, respectively, in an eating behavior test performed 4 h after snack ingestion. In vitro digestion experiments revealed that OEA release in intestinal digesta was greatly enhanced when the snack was liquid compared to the semi-solid structure. Kinetic investigations of several plasma parameters after liquid snack ingestion points towards different potential mechanism depending upon the minipig weight status, with an effect of the OEA+ liquid snack likely on endocannabinoid and other related N-acylethanolamine metabolism in normal-weight minipigs and on ketogenesis in obese ones.

Leukotriene A4 hydrolase inhibition improves age-related cognitive decline via modulation of synaptic function.

Leukotrienes, a class of inflammatory bioactive lipids, are well studied in the periphery, but less is known of their importance in the brain. We identified that the enzyme leukotriene A4 hydrolase (LTA4H) is expressed in healthy mouse neurons, and inhibition of LTA4H in aged mice improves hippocampal dependent memory. Single-cell nuclear RNA sequencing of hippocampal neurons after inhibition reveals major changes to genes important for synaptic organization, structure, and activity. We propose that LTA4H inhibition may act to improve cognition by directly inhibiting the enzymatic activity in neurons, leading to improved synaptic function. In addition, LTA4H plasma levels are increased in both aging and Alzheimer's disease and correlated with cognitive impairment. These results identify a role for LTA4H in the brain, and we propose that LTA4H inhibition may be a promising therapeutic strategy to treat cognitive decline in aging related diseases.

Brain-derived extracellular vesicles: Potential diagnostic biomarkers for central nervous system diseases.

Extracellular vesicles (EVs) are membrane-enclosed nanovesicles secreted by cells into the extracellular space and contain functional biomolecules, e.g. signaling receptors, bioactive lipids, nucleic acids, and proteins, which can serve as biomarkers. Neurons and glial cells secrete EVs, contributing to various physiological and pathological aspects of brain diseases. EVs confer their role in the bidirectional crosstalk between the central nervous system (CNS) and the periphery owing to their distinctive ability to cross the unique blood-brain barrier (BBB). Thus, EVs in the blood, cerebrospinal fluid (CSF), and urine can be intriguing biomarkers, enabling the minimally invasive diagnosis of CNS diseases. Although there has been an enormous interest in evaluating EVs as promising biomarkers, the lack of ultra-sensitive approaches for isolating and detecting brain-derived EVs (BDEVs) has hindered the development of efficient biomarkers. This review presents the recent salient findings of exosomal biomarkers, focusing on brain disorders. We summarize highly sensitive sensors for EV detection and state-of-the-art methods for single EV detection. Finally, the prospect of developing advanced EV analysis approaches for the non-invasive diagnosis of brain diseases is presented.

Reducing Dietary Polyunsaturated to Saturated Fatty Acids Ratio Improves Lipid and Glucose Metabolism in Obese Zucker Rats.

We investigated the influence of varying dietary polyunsaturated fatty acid (PUFA)/saturated fatty acids (SFA) ratios on insulin resistance (IR), fatty acid metabolism, N-acylethanolamine (NAE) bioactive metabolite levels, and mitochondrial function in lean and obese Zucker rats in a model designed to study obesity and IR from overnutrition. We provided diets with 7% fat (w/w), with either a low PUFA/SFA ratio of 0.48, predominantly comprising palmitic acid (PA), (diet-PA), or the standard AIN-93G diet with a high PUFA/SFA ratio of 3.66 (control, diet-C) over eight weeks. In obese rats on diet-PA versus diet-C, there were reductions in plasma triglycerides, cholesterol, glucose, insulin concentrations and improved muscle mitochondrial function, inflammatory markers and increased muscle N-oleoylethanolamine (OEA), a bioactive lipid that modulates lipid metabolism and metabolic flexibility. Elevated palmitic acid levels were found exclusively in obese rats, regardless of their diet, implying an endogenous production through de novo lipogenesis rather than from a dietary origin. In conclusion, a reduced dietary PUFA/SFA ratio positively influenced glucose and lipid metabolism without affecting long-term PA tissue concentrations. This likely occurs due to an increase in OEA biosynthesis, improving metabolic flexibility in obese rats. Our results hint at a pivotal role for balanced dietary PA in countering the effects of overnutrition-induced obesity.