Insulin-regulated serine and lipid metabolism drive peripheral neuropathy.

Diabetes represents a spectrum of disease in which metabolic dysfunction damages multiple organ systems including liver, kidneys and peripheral nerves1,2. Although the onset and progression of these co-morbidities are linked with insulin resistance, hyperglycaemia and dyslipidaemia3-7, aberrant non-essential amino acid (NEAA) metabolism also contributes to the pathogenesis of diabetes8-10. Serine and glycine are closely related NEAAs whose levels are consistently reduced in patients with metabolic syndrome10-14, but the mechanistic drivers and downstream consequences of this metabotype remain unclear. Low systemic serine and glycine are also emerging as a hallmark of macular and peripheral nerve disorders, correlating with impaired visual acuity and peripheral neuropathy15,16. Here we demonstrate that aberrant serine homeostasis drives serine and glycine deficiencies in diabetic mice, which can be diagnosed with a serine tolerance test that quantifies serine uptake and disposal. Mimicking these metabolic alterations in young mice by dietary serine or glycine restriction together with high fat intake markedly accelerates the onset of small fibre neuropathy while reducing adiposity. Normalization of serine by dietary supplementation and mitigation of dyslipidaemia with myriocin both alleviate neuropathy in diabetic mice, linking serine-associated peripheral neuropathy to sphingolipid metabolism. These findings identify systemic serine deficiency and dyslipidaemia as novel risk factors for peripheral neuropathy that may be exploited therapeutically.

[Mechanism of Jiaotai Pills in treatment of depression based on quantitative proteomics].

This study aimed to investigate the effect of Jiaotai Pills on protein expression in the hippocampus of the rat model of chronic unpredictable mild stress(CUMS)-induced depression by quantitative proteomics and explore the anti-depression mechanism of Jiaotai Pills. The SD rats were randomized into control, model, Jiaotai Pills, and fluoxetine groups(n=8). Other groups except the control group were subjected to CUMS modeling for 4 weeks. After 4 weeks of continuous administration, the changes of behavior and pathological morphology of the hippocampal tissue were observed. Proteins were extracted from the hippocampal tissue, and bioinformatics analysis was performed for the differentially expressed proteins(DEPs) identified by quantitative proteomics. Western blot was employed to verify the key DEPs. The results showed that Jiaotai Pills significantly alleviated the depression behaviors and hippocampal histopathological changes in the rat model of CUMS-induced depression. A total of 5 412 proteins were identified in the hippocampus of rats, including 65 DEPs between the control group and the model group and 35 DEPs between the Jiaotai Pills group and the model group. There were 16 DEPs with the same trend in the Jiaotai Pills group and the control group, which were mainly involved in sphingolipid, AMPK, and dopaminergic synapse signaling pathways. The Western blot results of Ppp2r2b, Cers1, and Ndufv3 in the hippocampus were consistent with the results of proteomics. In conclusion, Jiaotai Pills may play an anti-depression role by modulating the levels of Ppp2r2b, Cers1, Ndufv3 and other proteins and regulating sphingolipid, AMPK, and dopaminergic synapse signaling pathways.

LC-MS-based metabolomics reveals the in vivo effect of Shegan Mahuang Decoction in an OVA-induced rat model of airway hyperresponsiveness.

The traditional Chinese medicine (TCM) formula Shegan Mahuang Decoction (SMD) has been used for treating asthma with significant clinical efficacy, but its mechanism of action has not been well investigated. This study aimed to investigate the anti-asthma effects of SMD on ovalbumin (OVA)-induced airway hyperresponsiveness (AHR) in rats and its potential mechanisms using liquid chromatography-mass spectrometry (LC-MS)-based metabolomics combined with Gene Expression Omnibus (GEO) data mining. The results showed that the administration of SMD significantly attenuated OVA-induced lung histopathological changes. OVA-induced elevation of the immunoglobulin (IgE) and interleukin-4 (IL-4) levels was also inhibited by SMD. A total of 28 significantly changed metabolites in plasma were selected from metabolomics analysis. After treatment with SMD, 24 of them were negatively regulated and the related metabolisms were involved in multiple metabolic pathways such as sphingolipid metabolism and arachidonic acid metabolism. The differentially expressed genes (DEGs) were obtained by GEO data mining. The integrated pathway analysis highlighted 11 signaling pathways that were associated with the anti-asthma effect of SMD. Among them, the metabolite-gene-pathway network showed that the peroxisome proliferator-activated receptors (PPAR) signaling pathway might be the most significant one. This study revealed that SMD exerted an anti-asthma effect against OVA-induced AHR via comprehensively modulating the sphingolipid metabolism, arachidonic acid metabolism, and PPAR signaling, which indicated the synergistic effect of multi-component, multi-target, and multi-pathway of TCM in the treatment of the disease. This study expands our understanding of SMD in the treatment of asthma from a metabolomics perspective.

Vagus nerve stimulated by microbiota-derived hydrogen sulfide mediates the regulation of berberine on microglia in transient middle cerebral artery occlusion rats.

Amelioration of neuroinflammation via modulating microglia is a promising approach for cerebral ischemia therapy. The aim of the present study was to explore gut-brain axis signals in berberine-modulating microglia polarization following cerebral ischemia. The potential pathway was determined through analyzing the activation of the vagus nerve, hydrogen sulfide (H2 S) metabolism, and cysteine persulfides of transient receptor potential vanilloid 1 (TRPV1) receptor. The cerebral microenvironment feature was explored with a metabolomics assay. The data indicated that berberine ameliorated behavioral deficiency in transient middle cerebral artery occlusion rats through modulating microglia polarization and neuroinflammation depending on microbiota. Enhanced vagus nerve activity following berberine treatment was blocked by antibiotic cocktails, capsazepine, or sodium molybdate, respectively. Berberine-induced H2 S production was responsible for vagus nerve stimulation achieved through assimilatory and dissimilatory sulfate reduction with increased synthetic enzymes. Sulfation of the TRPV1 receptor resulted in vagus nerve activation and promoted the c-fos and ChAT in the nucleus tractus solitaries with berberine. Sphingolipid metabolism is the primary metabolic characteristic with berberine in the cerebral cortex, hippocampus, and cerebral spinal fluid disrupted by antibiotics. Berberine, in conclusion, modulates microglia polarization in a microbiota-dependent manner. H2 S stimulates the vagus nerve through TRPV1 is responsible for the berberine-induced gut-brain axis signal transmission. Sphingolipid metabolism might mediate the neuroinflammation amelioration following vagus afferent fiber activation.

Alterations in sphingolipid composition and mitochondrial bioenergetics represent synergistic therapeutic vulnerabilities linked to multidrug resistance in leukemia.

Modifications in sphingolipid (SL) metabolism and mitochondrial bioenergetics are key factors implicated in cancer cell response to chemotherapy, including chemotherapy resistance. In the present work, we utilized acute myeloid leukemia (AML) cell lines, selected to be refractory to various chemotherapeutics, to explore the interplay between SL metabolism and mitochondrial biology supportive of multidrug resistance (MDR). In agreement with previous findings in cytarabine or daunorubicin resistant AML cells, relative to chemosensitive wildtype controls, HL-60 cells refractory to vincristine (HL60/VCR) presented with alterations in SL enzyme expression and lipidome composition. Such changes were typified by upregulated expression of various ceramide detoxifying enzymes, as well as corresponding shifts in ceramide, glucosylceramide, and sphingomyelin (SM) molecular species. With respect to mitochondria, despite consistent increases in both basal respiration and maximal respiratory capacity, direct interrogation of the oxidative phosphorylation (OXPHOS) system revealed intrinsic deficiencies in HL60/VCR, as well as across multiple MDR model systems. Based on the apparent requirement for augmented SL and mitochondrial flux to support the MDR phenotype, we explored a combinatorial therapeutic paradigm designed to target each pathway. Remarkably, despite minimal cytotoxicity in peripheral blood mononuclear cells (PBMC), co-targeting SL metabolism, and respiratory complex I (CI) induced synergistic cytotoxicity consistently across multiple MDR leukemia models. Together, these data underscore the intimate connection between cellular sphingolipids and mitochondrial metabolism and suggest that pharmacological intervention across both pathways may represent a novel treatment strategy against MDR.

Antioxidants Supplementation Reduces Ceramide Synthesis Improving the Cardiac Insulin Transduction Pathway in a Rodent Model of Obesity.

Obesity-related disruption in lipid metabolism contributes to cardiovascular dysfunction. Despite numerous studies on lipid metabolism in the left ventricle, there is no data describing the influence of n-acetylcysteine (NAC) and α-lipoic acid (ALA), as glutathione precursors, on sphingolipid metabolism, and insulin resistance (IR) occurrence. The aim of our experiment was to evaluate the influence of chronic antioxidants administration on myocardial sphingolipid state and intracellular insulin signaling as a potential therapeutic strategy for obesity-related cardiovascular IR. The experiment was conducted on male Wistar rats fed a standard rodent chow or a high-fat diet with intragastric administration of NAC or ALA for eight weeks. Cardiac and plasma sphingolipid species were assessed by high-performance liquid chromatography (HPLC). The proteins expressed from sphingolipid and insulin signaling pathways were determined by Western blot. Antioxidant supplementation markedly reduced ceramide accumulation by lowering the expression of selected proteins from the sphingolipid pathway and simultaneously increased the myocardial sphingosine-1-phosphate level. Moreover, NAC and ALA augmented the expression of GLUT4 and the phosphorylation state of Akt (Ser473) and GSK3ß (Ser9), which improved the intracellular insulin transduction pathway. Based on our results, we may postulate that NAC and ALA have a beneficial influence on the cardiac ceramidose under IR conditions.

Sphingolipid metabolism governs Purkinje cell patterned degeneration in Atxn1[82Q]/+ mice.

Patterned degeneration of Purkinje cells (PCs) can be observed in a wide range of neuropathologies, but mechanisms behind nonrandom cerebellar neurodegeneration remain unclear. Sphingolipid metabolism dyshomeostasis typically leads to PC neurodegeneration; hence, we questioned whether local sphingolipid balance underlies regional sensitivity to pathological insults. Here, we investigated the regional compartmentalization of sphingolipids and their related enzymes in the cerebellar cortex in healthy and pathological conditions. Analysis in wild-type animals revealed higher sphingosine kinase 1 (Sphk1) levels in the flocculonodular cerebellum, while sphingosine-1-phosphate (S1P) levels were higher in the anterior cerebellum. Next, we investigated a model for spinocerebellar ataxia type 1 (SCA1) driven by the transgenic expression of the expanded Ataxin 1 protein with 82 glutamine (82Q), exhibiting severe PC degeneration in the anterior cerebellum while the flocculonodular region is preserved. In Atxn1[82Q]/+ mice, we found that levels of Sphk1 and Sphk2 were region-specific decreased and S1P levels increased, particularly in the anterior cerebellum. To determine if there is a causal link between sphingolipid levels and neurodegeneration, we deleted the Sphk1 gene in Atxn1[82Q]/+ mice. Analysis of Atxn1[82Q]/+; Sphk1-/- mice confirmed a neuroprotective effect, rescuing a subset of PCs in the anterior cerebellum, in domains reminiscent of the modules defined by AldolaseC expression. Finally, we showed that Sphk1 deletion acts on the ATXN1[82Q] protein expression and prevents PC degeneration. Taken together, our results demonstrate that there are regional differences in sphingolipid metabolism and that this metabolism is directly involved in PC degeneration in Atxn1[82Q]/+ mice.

Ceramide synthase 6 mediates sex-specific metabolic response to dietary folic acid in mice.

Folic acid-fortified foods and multi-vitamin supplements containing folic acid (FA) are widely used around the world, but the exact mechanisms/metabolic effects of FA are not precisely identified. We have demonstrated that Ceramide Synthase 6 (CerS6) and C16:0-ceramide mediate response to folate stress in cultured cells. Here we investigated the dietary FA effects on mouse liver metabolome, with a specific focus on sphingolipids, CerS6 and C16:0-ceramide. Wild-type and CerS6-/- mice were fed FA-deficient, control, or FA over-supplemented diets for 4 weeks. After dietary treatment, liver concentrations of ceramides, sphingomyelins and hexosylceramides were measured by LC-MS/MS and complemented by untargeted metabolomic characterization of mouse livers. Our study shows that alterations in dietary FA elicit multiple sphingolipid responses mediated by CerS6 in mouse livers. Folic acid-deficient diet elevated C14:0-, C18:0- and C20:0- but not C16:0-ceramide in WT male and female mice. Additionally, FA over-supplementation increased multiple sphingomyelin species, including total sphingomyelins, in both sexes. Of note, concentrations of C14:0- and C16:0-ceramides and hexosylceramides were significantly higher in female livers than in male. The latter were increased by FD diet, with no difference between sexes in total pools of these sphingolipid classes. Untargeted liver metabolomic analysis concurred with the targeted measurements and showed broad effects of dietary FA and CerS6 status on multiple lipid classes including sex-specific effects on phosphatidylethanolamines and diacylglycerols. Our study demonstrates that both dietary FA and CerS6 status exhibit pleiotropic and sex-dependent effects on liver metabolism, including hepatic sphingolipids, diacylglycerols, long chain fatty acids, and phospholipids.

Metabolomics and integrated network pharmacology analysis reveal Tricin as the active anti-cancer component of Weijing decoction by suppression of PRKCA and sphingolipid signaling.

Currently, conventional methods of treating non-small cell lung cancer (NSCLC) have many disadvantages. An alternative effective therapy with minimal adverse reactions is urgently needed. Weijing decoction (WJD), which is a classic ancient Chinese herbal prescription, has been used successfully to treat pulmonary system diseases containing lung cancer in the clinic. However, the key active component and target of Weijing decoction are still unexplored. Therefore, for the first time, our study aims to investigate the pharmacological treatment mechanism of Weijing decoction in treating NSCLC via an integrated model of network pharmacology, metabolomics and biological methods. Network pharmacology results conjectured that Tricin is a main bioactive component in this formula which targets PRKCA to suppress cancer cell growth. Metabolomics analysis demonstrated that sphingosine-1-phosphate, which is regulated by sphingosine kinase 1 and sphingosine kinase 2, is a differential metabolite in plasma between the WJD-treated group and the control group, participating in the sphingolipid signaling. In vitro experiments demonstrated that Tricin had vital effects on the proliferation, pro-apoptosis, migration and colony formation of Lewis lung carcinoma cells. Through a series of validation assays, Tricin inhibited the tumor growth mainly by suppressing PRKCA/SPHK/S1P signaling and antiapoptotic signaling. On the other hand, Weijing formula could inhibit the tumor growth and prolong the survival time. A high dosage of Tricin was much more potent in animal experiments. In conclusion, we confirmed that Weijing formula and its primary active compound Tricin are promising alternative treatments for NSCLC patients.

Regulatory role of mammalian target of rapamycin signaling in exosome secretion and osteogenic changes in smooth muscle cells lacking acid ceramidase gene.

Acid ceramidase (murine gene code: Asah1) (50 kDa) belongs to N-terminal nucleophile hydrolase family. This enzyme is located in the lysosome, which mediates conversion of ceramide (CER) into sphingosine and free fatty acids at acidic pH. CER plays an important role in intracellular sphingolipid metabolism and its increase causes inflammation. The mammalian target of rapamycin complex 1 (mTORC1) signaling on late endosomes (LEs)/lysosomes may control cargo selection, membrane biogenesis, and exosome secretion, which may be fine controlled by lysosomal sphingolipids such as CER. This lysosomal-CER-mTOR signaling may be a crucial molecular mechanism responsible for development of arterial medial calcification (AMC). Torin-1 (5 mg/kg/day), an mTOR inhibitor, significantly decreased aortic medial calcification accompanied with decreased expression of osteogenic markers like osteopontin (OSP) and runt-related transcription factor 2 (RUNX2) and upregulation of smooth muscle 22α (SM22-α) in mice receiving high dose of Vitamin D (500 000 IU/kg/day). Asah1fl/fl /SMCre mice had markedly increased co-localization of mTORC1 with lysosome-associated membrane protein-1 (Lamp-1) (lysosome marker) and decreased co-localization of vacuolar protein sorting-associated protein 16 (VPS16) (a multivesicular bodies [MVBs] marker) with Lamp-1, suggesting mTOR activation caused reduced MVBs interaction with lysosomes. Torin-1 significantly reduced the co-localization of mTOR vs Lamp-1, increased lysosome-MVB interaction which was associated with reduced accumulation of CD63 and annexin 2 (exosome markers) in the coronary arterial wall of mice. Using coronary artery smooth muscle cells (CASMCs), Pi -stimulation significantly increased p-mTOR expression in Asah1fl/fl /SMCre CASMCs as compared to WT/WT cells associated with increased calcium deposition and mineralization. Torin-1 blocked Pi -induced calcium deposition and mineralization. siRNA mTOR and Torin-1 significantly reduce co-localization of mTORC1 with Lamp-1, increased VPS16 vs Lamp-1 co-localization in Pi -stimulated CASMCs, associated with decreased exosome release. Functionally, Torin-1 significantly reduces arterial stiffening as shown by restoration from increased pulse wave velocity and decreased elastin breaks. These results suggest that lysosomal CER-mTOR signaling may play a critical role for the control of lysosome-MVB interaction, exosome secretion and arterial stiffening during AMC.

Chemical and genetic rescue of in vivo progranulin-deficient lysosomal and autophagic defects.

In 2006, GRN mutations were first linked to frontotemporal dementia (FTD), the leading cause of non-Alzheimer dementias. While much research has been dedicated to understanding the genetic causes of the disease, our understanding of the mechanistic impacts of GRN deficiency has only recently begun to take shape. With no known cure or treatment available for GRN-related FTD, there is a growing need to rapidly advance genetic and/or small-molecule therapeutics for this disease. This issue is complicated by the fact that, while lysosomal dysfunction seems to be a key driver of pathology, the mechanisms linking a loss of GRN to a pathogenic state remain unclear. In our attempt to address these key issues, we have turned to the nematode, Caenorhabditis elegans, to model, study, and find potential therapies for GRN-deficient FTD. First, we show that the loss of the nematode GRN ortholog, pgrn-1, results in several behavioral and molecular defects, including lysosomal dysfunction and defects in autophagic flux. Our investigations implicate the sphingolipid metabolic pathway in the regulation of many of the in vivo defects associated with pgrn-1 loss. Finally, we utilized these nematodes as an in vivo tool for high-throughput drug screening and identified two small molecules with potential therapeutic applications against GRN/pgrn-1 deficiency. These compounds reverse the biochemical, cellular, and functional phenotypes of GRN deficiency. Together, our results open avenues for mechanistic and therapeutic research into the outcomes of GRN-related neurodegeneration, both genetic and molecular.

The Role of Fatty Acids in Ceramide Pathways and Their Influence on Hypothalamic Regulation of Energy Balance: A Systematic Review.

Obesity is a global health issue for which no major effective treatments have been well established. High-fat diet consumption is closely related to the development of obesity because it negatively modulates the hypothalamic control of food intake due to metaflammation and lipotoxicity. The use of animal models, such as rodents, in conjunction with in vitro models of hypothalamic cells, can enhance the understanding of hypothalamic functions related to the control of energy balance, thereby providing knowledge about the impact of diet on the hypothalamus, in addition to targets for the development of new drugs that can be used in humans to decrease body weight. Recently, sphingolipids were described as having a lipotoxic effect in peripheral tissues and the central nervous system. Specifically, lipid overload, mainly from long-chain saturated fatty acids, such as palmitate, leads to excessive ceramide levels that can be sensed by the hypothalamus, triggering the dysregulation of energy balance control. However, no systematic review has been undertaken regarding studies of sphingolipids, particularly ceramide and sphingosine-1-phosphate (S1P), the hypothalamus, and obesity. This review confirms that ceramides are associated with hypothalamic dysfunction in response to metaflammation, endoplasmic reticulum (ER) stress, and lipotoxicity, leading to insulin/leptin resistance. However, in contrast to ceramide, S1P appears to be a central satiety factor in the hypothalamus. Thus, our work describes current evidence related to sphingolipids and their role in hypothalamic energy balance control. Hypothetically, the manipulation of sphingolipid levels could be useful in enabling clinicians to treat obesity, particularly by decreasing ceramide levels and the inflammation/endoplasmic reticulum stress induced in response to overfeeding with saturated fatty acids.

The microbiome affects liver sphingolipids and plasma fatty acids in a murine model of the Western diet based on soybean oil.

Studies in mice using germfree animals as controls for microbial colonization have shown that the gut microbiome mediates diet-induced obesity. Such studies use diets rich in saturated fat, however, Western diets in the United States America are enriched in soybean oil, composed of unsaturated fatty acids, either linoleic or oleic acid. Here, we addressed whether the microbiome is a variable in fat metabolism in mice on a soybean oil diet. We used conventionally-raised, low-germ, and germfree mice fed for 10 weeks diets either high or low in high-linoleic-acid soybean oil as the sole source of fat. Conventional and germfree mice gained relative fat weight and all mice consumed more calories on the high fat vs. low fat soybean oil diet. Plasma fatty acid levels were generally dependent on diet, with microbial colonization status affecting iso-C18:0, C20:3n-6, C14:0, and C15:0 levels. Colonization status, but not diet, impacted levels of liver sphingolipids including ceramides, sphingomyelins, and sphinganine. Our results confirm that absorbed fatty acids are mainly a reflection of the diet and that microbial colonization influences liver sphingolipid pools regardless of diet.

Characterization of brain-derived extracellular vesicle lipids in Alzheimer's disease.

Lipid dyshomeostasis is associated with the most common form of dementia, Alzheimer's disease (AD). Substantial progress has been made in identifying positron emission tomography and cerebrospinal fluid biomarkers for AD, but they have limited use as front-line diagnostic tools. Extracellular vesicles (EVs) are released by all cells and contain a subset of their parental cell composition, including lipids. EVs are released from the brain into the periphery, providing a potential source of tissue and disease specific lipid biomarkers. However, the EV lipidome of the central nervous system is currently unknown and the potential of brain-derived EVs (BDEVs) to inform on lipid dyshomeostasis in AD remains unclear. The aim of this study was to reveal the lipid composition of BDEVs in human frontal cortex, and to determine whether BDEVs have an altered lipid profile in AD. Using semi-quantitative mass spectrometry, we describe the BDEV lipidome, covering four lipid categories, 17 lipid classes and 692 lipid molecules. BDEVs were enriched in glycerophosphoserine (PS) lipids, a characteristic of small EVs. Here we further report that BDEVs are enriched in ether-containing PS lipids, a finding that further establishes ether lipids as a feature of EVs. BDEVs in the AD frontal cortex offered improved detection of dysregulated lipids in AD over global lipid profiling of this brain region.  AD BDEVs had significantly altered glycerophospholipid and sphingolipid levels, specifically increased plasmalogen glycerophosphoethanolamine and decreased polyunsaturated fatty acyl containing lipids, and altered amide-linked acyl chain content in sphingomyelin and ceramide lipids relative to CTL. The most prominent alteration was a two-fold decrease in lipid species containing anti-inflammatory/pro-resolving docosahexaenoic acid. The in-depth lipidome analysis provided in this study highlights the advantage of EVs over more complex tissues for improved detection of dysregulated lipids that may serve as potential biomarkers in the periphery.

Serum Metabolomics Reveals Underlying Mechanisms of Cholesterol-Lowering Effects of Oat Consumption: A Randomized Controlled Trial in a Mildly Hypercholesterolemic Population.

INTRODUCTION: The purpose of this study is to examine the effects of oat supplementation on serum lipid in a population of adults with mild hypercholesterolemia and reveal the underlying mechanisms with serum untargeted metabolomics. METHODS AND RESULTS: In this placebo-controlled trial, 62 participants from Nanjing, China, with mild elevations in cholesterol are randomly assigned to receive 80 g oats (containing 3 g beta-glucan) or rice daily for 45 days. Fasting blood samples are collected at the beginning, middle, and end of the trial. Compared with the rice group, oat consumption significantly decreases serum total cholesterol (TC) (-8.41%, p = 0.005), low-density lipoprotein cholesterol (LDL-c) (-13.93%, p = 0.001), and non high-density lipoprotein cholesterol (non-HDL-c) (-10.93%, p = 0.017) levels. There are no significant between-group differences in serum triglyceride (TG), apolipoprotein B (Apo B), glycated albumin, or fasting blood glucose levels. An orthogonal partial least squares discriminant analysis (OPLS-DA) suggests a clear separation in metabolic profiles between the groups after the intervention. Twenty-one metabolites in the oat group are significantly different from those in the rice group, among which 14 metabolites show a decreased trend. In comparison, seven metabolites show an increased trend. Correlations analysis from both groups indicate that most metabolites [e.g., sphinganine and phosphatidylcholine (PC)(20:5(5Z,8Z,11Z,14Z,17Z)/20:1(11Z))] have positive correlations with serum cholesterol levels. Kyoto Encyclopedia of Gene and Genomes pathway analysis suggests that oat consumption regulated glycerophospholipid, alanine, aspartate and glutamate, sphingolipid, and retinol metabolism. CONCLUSION: Oat consumption has beneficial effects on serum lipids profiles. The underlying mechanisms involve glycerophospholipid, alanine, aspartate and glutamate, sphingolipid, and retinol metabolism in adults.

Structure-dependent absorption of atypical sphingoid long-chain bases from digestive tract into lymph.

BACKGROUND: Dietary sphingolipids have various biofunctions, including skin barrier improvement and anti-inflammatory and anti-carcinoma properties. Long-chain bases (LCBs), the essential backbones of sphingolipids, are expected to be important for these bioactivities, and they vary structurally between species. Given these findings, however, the absorption dynamics of each LCB remain unclear. METHODS: In this study, five structurally different LCBs were prepared from glucosylceramides (GlcCers) with LCB 18:2(4E,8Z);2OH and LCB 18:2(4E,8E);2OH moieties derived from konjac tuber (Amorphophallus konjac), from GlcCers with an LCB 18(9Me):2(4E,8E);2OH moiety derived from Tamogi mushroom (Pleurotus cornucopiae var. citrinopileatus), and from ceramide 2-aminoethyphosphonate with LCB 18:3(4E,8E,10E);2OH moiety and LCB 18(9Me):3(4E,8E,10E);2OH moiety derived from giant scallop (Mizuhopecten yessoensis), and their absorption percentages and metabolite levels were analyzed using a lymph-duct-cannulated rat model via liquid chromatography tandem mass spectrometry (LC/MS/MS) with a multistage fragmentation method. RESULTS: The five orally administered LCBs were absorbed and detected in chyle (lipid-containing lymph) as LCBs and several metabolites including ceramides, hexosylceramides, and sphingomyelins. The absorption percentages of LCBs were 0.10-1.17%, depending on their structure. The absorption percentage of LCB 18:2(4E,8Z);2OH was the highest (1.17%), whereas that of LCB 18:3(4E,8E,10E);2OH was the lowest (0.10%). The amount of sphingomyelin with an LCB 18:2(4E,8Z);2OH moiety in chyle was particularly higher than sphingomyelins with other LCB moieties. CONCLUSIONS: Structural differences among LCBs, particularly geometric isomerism at the C8-C9 position, significantly affected the absorption percentages and ratio of metabolites. This is the first report to elucidate that the absorption and metabolism of sphingolipids are dependent on their LCB structure. These results could be used to develop functional foods that are more readily absorbed.

Ex vivo assay to evaluate the efficacy of drugs targeting sphingolipids in preventing SARS-CoV-2 infection of nasal epithelial cells.

This protocol enables the testing of drugs against infection of epithelial cells with SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2), using pseudo-typed replication deficient vesicular stomatitis virus particles (pp-VSV) presenting the SARS-CoV-2 spike protein. After treating human volunteers with amitriptyline, an approved antidepressant and inhibitor of the acid sphingomyelinase, freshly isolated nasal epithelial cells were infected ex vivo and infection levels were quantified. This protocol offers the possibility to rapidly test the efficacy of potential drugs in the fight against COVID-19. For complete details on the use and execution of this protocol, please refer to Carpinteiro et al. (2020).

Correlation analysis between extracts and endogenous metabolites to characterise the influence of salt-processing on compatibility mechanism of 'Psoraleae Fructus & Foeniculi Fructus'.

ETHNOPHARMACOLOGICAL RELEVANCE: 'Salt-processed Psoraleae Fructus & salt-processed Foeniculi Fructus' (sPF&sFF) is a common Chinese medicinal combination for treating diarrhoea. However, it is not clear how sPF and sFF work together, and why salt-processing is necessary. AIM OF THE STUDY: To investigate the compatibility mechanism of sPF&sFF and the influence of salt-processing on it. MATERIALS AND METHODS: Firstly, the metabolomics approach was appliedto screen the differential components between four (s)PF&(s)FF extracts, i.e., sPF&sFF, sPF&FF, PF&sFF, and PF&FF extracts. Then, an in vivo metabolomics study was carried out to filter critical metabolites reflecting the curative effects of (s)PF&(s)FF, and construct a metabolic network. Finally, a correlation analysis between chemical components in extracts and critical metabolites in vivo was performed to find out the synergistic and/or antagonistic effects between herbs as well as the influence of salt-processing. RESULTS: Salt-processing had a direct influence on the contents of chemical components in sPF and sFF extracts, and there existed positive/negative correlations between the content change of chemical components and the effects of critical metabolites. Therefore, salt-processing indirectly affected on these correlations and was (i) conducive to the positive effects of sPF and sFF on bile acids, making sFF play a synergistic role, thereby, sPF&sFF could perform better than sPF and other three combinations and effectively relieve the symptoms of fatty diarrhoea, osmotic diuresis, malnutrition, and weight loss; (ii) conducive to the positive effects of sPF on triacylglycerol, 12(S)-hydroxyeicosatetraenoic acid, cholesterol, and arachidonic acid, and adverse to that of sFF, making sFF play an antagonistic role, thereby, sPF&sFF could prevent a series of side effects caused by over-regulation and suitably relieve the symptoms of osmotic diuresis, polyuria, malnutrition, and weight loss; and (iii) adverse to the positive effects of sPF and sFF on thromboxane A2, sphinganine and sphingosine, making sFF play a synergistic role, thereby, sPF&sFF could prevent a series of side effects and moderately relieve the symptoms of metabolic diarrhoea and polyuria. CONCLUSIONS: Salt-processing indirectly affected on the correlations between chemical components in extracts and critical metabolites in vivo, and exhibited both conducive and adverse effects on the efficacy, making sPF and sFF cooperate with each other to moderately repair the metabolic disorders. Thereby, sPF&sFF could suitably relieve the diarrhoea and polyuria symptoms in the model and exert the most appropriate efficacy. Moreover, this novel strategy provided a feasible approach for further studying the compatibility mechanism of herbs.

An overview of ongoing clinical trials assessing pharmacological therapeutic strategies to manage chemotherapy-induced peripheral neuropathy, based on preclinical studies in rodent models.

Chemotherapy-induced peripheral neuropathy (CIPN) is a major dose-limiting side effect induced by a variety of chemotherapeutic agents. Symptoms are mainly sensory: pain, tingling, numbness, and temperature sensitivity. They may require the tapering of chemotherapy regimens or even their cessation; thus, the prevention/treatment of CIPN is critical to increase effectiveness of cancer treatment. However, CIPN management is mainly based on conventional neuropathic pain treatments, with poor clinical efficacy. Therefore, significant effort is made to identify new pharmacological targets to prevent/treat CIPN. Animal modeling is a key component in predicting human response to drugs and in understanding the pathophysiological mechanisms underlying CIPN. In fact, studies performed in rodents highlighted several pharmacological targets to treat/prevent CIPN. This review provides updated information about ongoing clinical trials testing drugs for the management of CIPN and presents some of their proof-of-concept studies conducted in rodent models. The presented drugs target oxidative stress, renin-angiotensin system, glutamatergic neurotransmission, sphingolipid metabolism, neuronal uptake transporters, nicotinamide adenine dinucleotide metabolism, endocannabinoid system, transient receptor potential channels, and serotoninergic receptors. As some clinical trials focus on the effect of the drugs on pain, others evaluate their efficacy by assessing general neuropathy. Moreover, based on studies conducted in rodent models, it remains unclear if some of the tested drugs act in an antinociceptive fashion or have neuroprotective properties. Thus, further investigations are needed to understand their mechanism of action, as well as a global standardization of the methods used to assess efficacy of new therapeutic strategies in the treatment of CIPN.

Omega 3 Improves Both apoB100-containing Lipoprotein Turnover and their Sphingolipid Profile in Hypertriglyceridemia.

CONTEXT: Evidence for an association between sphingolipids and metabolic disorders is increasingly reported. Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs) improve apolipoprotein B100 (apoB100)-containing lipoprotein metabolism, but their effects on the sphingolipid content in lipoproteins remain unknown. OBJECTIVES: In subjects with hypertriglyceridemia, we analyzed the effect of n-3 LC-PUFAs on the turnover apoB100-containing lipoproteins and on their sphingolipid content and looked for the possible association between these lipid levels and apoB100-containing lipoprotein turnover parameters. METHODS: Six subjects underwent a kinetic study before and after n-3 supplementation for 2 months with 1 g of fish oil 3 times day containing 360 mg of eicosapentaenoic acid (EPA) and 240 mg of docosahexaenoic acid (DHA) in the form of triglycerides. We examined apoB100-containing lipoprotein turnover by primed perfusion labeled [5,5,5-2H3]-leucine and determined kinetic parameters using a multicompartmental model. We quantified sphingolipid species content in lipoproteins using mass spectrometry. RESULTS: Supplementation decreased very low-density lipoprotein (VLDL), triglyceride, and apoB100 concentrations. The VLDL neutral and polar lipids showed increased n-3 LC-PUFA and decreased n-6 LC-PUFA content. The conversion rate of VLDL1 to VLDL2 and of VLDL2 to LDL was increased. We measured a decrease in total apoB100 production and VLDL1 production. Supplementation reduced the total ceramide concentration in VLDL while the sphingomyelin content in LDL was increased. We found positive correlations between plasma palmitic acid and VLDL ceramide and between VLDL triglyceride and VLDL ceramide, and inverse correlations between VLDL n-3 LC-PUFA and VLDL production. CONCLUSION: Based on these results, we hypothesize that the improvement in apoB100 metabolism during n-3 LC-PUFA supplementation is contributed to by changes in sphingolipids.