Ceramide Levels Research Articles

TMET-29. TARGETING IDH1-MUTATED OLIGODENDROGLIOMA WITH ACID CERAMIDASE INHIBITORS

Abstract BACKGROUND Currently, an estimated 14,950 people lives with oligodendroglioma in the United States. Oligodendroglioma is genetically defined as a tumor harboring isocitrate dehydrogenase 1 or 2 mutations (IDH1mut/IDH2mut). Previously, we reported that in IDH1mut gliomas, D-2HG, the product of IDH1 mutant enzyme produces an increase in monounsaturated fatty acid levels that are incorporated into ceramides, tilting the S1P-to-ceramide rheostat toward apoptosis. Herein, we exploited this imbalance to further induce and IDHmut-specific glioma cell death. METHODS TCGA and CCGA data were used to explore the association between acid ceramidase (AC) gene expression and patient survival. CCK8 viability assays were carried out to measure the sensitivity of glioma cell lines to acid ceramidase inhibitors. Western blot and liquid chromatography-mass spectrometry analyses were performed for studying the mechanism of action of acid ceramidase inhibitors. The in vivo efficacy of the SABRAC drug, an irreversible inhibitor of AC, was evaluated in an orthotopic oligodendroglioma xenograft mice model using TS603 patient-derived oligodendroglioma cells. RESULTS. We report for the first time that the inhibition of acid ceramidase (AC) induces apoptosis and increases the survival of mice with IDH1mut oligodendroglioma. We demonstrated an IDH1mut-specific cytotoxicity of SABRAC, in patient-derived oligodendroglioma cells. Exploring the mechanism of action of this drug, we found that SABRAC activates both extrinsic and intrinsic apoptosis in an ER stress-independent manner, pointing to a direct action of AC-related ceramides in mitochondria permeability. The activation of apoptosis detected under SABRAC treatment was associated with up to a 30-fold increase in some ceramide levels and its derivatives from the salvage pathway. CONCLUSIONS We propose AC as a novel therapeutic target in oligodendroglioma with IDH1mut and we are conducting additional preclinical testing.

Efficacy of Pseudo-Ceramide Absorption Into the Stratum Corneum and Effects on Transepidermal Water Loss and the Ceramide Profile: A Randomized Controlled Trial.

Changes in the level or profile of ceramides are associated with decreased stratum corneum (SC) barrier function. Topical application of a pseudo-ceramide (pCer)-containing moisturizer can improve barrier function. Additionally, pCer that absorbs into the SC may improve ceramide profiles. We investigated the relationship between pCer absorption into the SC and SC properties and determined the efficacyof a pCer-containing spray compared with that of a commercial spray without pCer. Patients with self-perceived dry and sensitive skin and decreased barrier function (transepidermal water loss [TEWL] > 10 g/m2h) were randomized into two groups to topically apply a pCer-containing spray (test group; N = 33) or commercial spray without pCer (control group; N = 19) twice daily as a single-blind study. SC function and ceramide properties were investigated before and after 4 weeks of application. In the test group, the ceramide (NP)/(NS) ratio proportionally increased with the pCer application level after 4 weeks of pCer-containing spray application. In the control group, there were no changes in SC function after topical application of the commercially available spray without pCer; however, the SC water content, TEWL, SC cell area, and scaling score improved in the test group. Furthermore, the changes in TEWL in the test group were significantly negatively correlated with the pCer application level. The efficacy of pCer-containing sprays for those who have sensitive skin with impaired barrier function was demonstrated. Furthermore, the improvement in SC barrier function induced by pCer may contribute to normalizing the SC ceramide profile.

Ion Mobility QTOF-MS Untargeted Lipidomics of Human Serum Reveals a Metabolic Fingerprint for GNE Myopathy

GNE myopathy, also known as hereditary inclusion body myopathy (HIBM), is a rare genetic muscle disorder marked by a gradual onset of muscle weakness in young adults. GNE myopathy (GNEM) is caused by bi-allelic variants in the UDP-N-acetylglucosamine 2-epimerase (UDP-GlcNAc 2-epimerase)/N-acetylmannosamine kinase (ManNAc kinase) gene (GNE), clinically resulting in the loss of ambulation within 10–20 years from the onset of the initial symptoms. The disease’s mechanism is poorly understood and non-invasive biomarkers are lacking, hindering effective therapy development. Based on the available evidence, we employed a lipidomic approach to study the serum lipid profile of GNE patients. The multivariate statistical analysis revealed a downregulation of carnitines, as well as of lysophosphatidylcholines, in sera samples derived from GNEM patients. Furthermore, we identified lower levels of sphingomyelins and, concomitantly, high levels of ceramides in serum samples from GNEM patients when compared to control samples derived from healthy donors. Moreover, the GNEM serum samples showed the upregulation of Krebs cycle intermediates, in addition to a decrease in oxaloacetic acid. The correlated data gathered in this study can offer a promising diagnostic panel of complex lipids and polar metabolites that can be used in clinic for GNEM in terms of a metabolic fingerprint measurable in a minimally invasive manner.

Association between the plasma ceramide and coronary microvascular resistance

BackgroundPlasma ceramide plays a potentially significant role in the pathogenesis of coronary microvascular dysfunction. However, the relationship between plasma ceramide and coronary microvascular resistance in patients remains unclear. This study aimed to evaluate the association between plasma ceramide levels, as well as their distinct ratios, and coronary microvascular resistance.MethodsThis single-center observational study retrospectively enrolled patients who underwent both ceramide measurement and coronary angiography during hospitalization. The microvascular resistance of the coronary arteries was assessed in all patients using the angiography-derived index of microcirculatory resistance (Angio-IMR). The cumulative coronary microvascular resistance was calculated by summing the microvascular resistance of the three main coronary arteries. Multiple linear and logistic regression analyses were employed to evaluate the relationship between plasma ceramide and cumulative coronary microvascular resistance. Restricted cubic spline (RCS) analysis was conducted to investigate the association between plasma ceramide levels and cumulative coronary microvascular resistance. Receiver operating characteristic (ROC) curves were employed to evaluate the predictive value of plasma ceramide for coronary microvascular resistance. Additionally, subgroup analyses and interaction tests were performed.ResultsA total of 225 patients were included in this study, with a median cumulative coronary microvascular resistance of 48.04 (40.32–56.73). After adjusting for potential confounding factors, both plasma 16:0 ceramide and the 16:0/24:0 ceramide ratio were positively associated with cumulative coronary microvascular resistance [standardized β ± standard error: 75.05 ± 8.46 (P < 0.001) and 91.72 ± 20.41 (P < 0.001), respectively]. Similar independent associations were observed in predicting high cumulative microvascular resistance [β = 8.03 ± 1.91 (P < 0.001) and 9.98 ± 3.88 (P = 0.010), respectively]. Additionally, a significant nonlinear relationship was observed between plasma 16:0 ceramide, the 16:0/24:0 ceramide ratio, and cumulative coronary microvascular resistance (P for nonlinear < 0.05). The ROC analysis revealed that the optimal cut-off for plasma 16:0 ceramide is 0.178 µmol/L, with a specificity of 57.1% and a sensitivity of 91.2%. For the 16:0/24:0 ceramide ratio, the optimal cut-off is 0.072, yielding a specificity of 73.2% and a sensitivity of 54.9%. Subgroup analysis indicated that the association between plasma ceramide and coronary microvascular resistance was trending toward non-significance in patients with acute coronary syndrome (ACS).ConclusionsA significant nonlinear relationship exists between plasma ceramide and coronary microvascular resistance, which holds important clinical implications for the risk stratification of coronary microvascular disease. New insights into the potential effects of ceramides enhance our understanding of the complex mechanisms underlying coronary microvascular disease and warrant further investigation in a broader population.Graphical abstract

High-coverage targeted lipidomics revealed novel profile of serum lipid dysregulation in adult growth hormone deficiency

Purpose: Patients with adult growth hormone deficiency (AGHD) are at increased risk of metabolic syndrome. Despite extensive research efforts in recent decades, the lipid metabolism pattern of AGHD has yet to be thoroughly characterized. Methods: In this study, we used lipidomics analysis of fasting serum samples from 30 AGHD patients due to intracranial germ cell tumors (iGCTs) and 30 age-, gender-, and body mass index (BMI)-matched healthy controls to investigate the serum lipidomic pattern of AGHD patients due to iGCTs. We meticulously quantified 534 serum lipids from 29 classes using high-coverage targeted lipidomics technology in conjunction with a robust bioinformatics pipeline. Results: Our results revealed an AGHD-specific dynamic change in serum lipidomic profile, manifested by higher overall levels of many lipid subclasses, including triacylglycerols (TAGs), diacylglycerols (DAGs), phosphatidylglycerols, phosphatidylethanolamines (PE), phosphatidylcholines (PC), phosphatidylinositols, ceramides, and bis(monoacylglycerol)phosphates than in healthy controls, and a distinct lowering level in alkyl PE (PE-O) and alkyl PC (PC-O). AGHD individuals with non-alcoholic fatty liver disease showed specific changes in higher TAG and DAG subclass levels. Alterations in lipid profiles may contribute to metabolic dysregulation in AGHD patients. TAGs, PCs, and PE-fatty acids positively correlated with BMI, fasting insulin, insulin resistance index, and adverse lipid parameters. In contrast, ether-linked PE-O, PC-O, and LysoPE-O showed a negative correlation. Conclusions: This study has significantly expanded the current understanding of lipid dysregulation in AGHD patients due to iGCT. These findings can potentially guide future research and the development of monitoring and intervention strategies.

Preclinical Multi-Omic Assessment of Pioglitazone in Skeletal Muscles of Mice Implanted with Human HER2/neu Overexpressing Breast Cancer Xenografts

Background/Objectives: Breast cancer (BC) is the second most commonly diagnosed cancer worldwide and is accompanied by fatigue during both active disease and remission in the majority of cases. Our lab has measured fatigue in isolated muscles from treatment-naive BC patient-derived orthotopic xenograft (BC-PDOX) mice. Here, we conducted a preclinical trial of pioglitazone in BC-PDOX mice to determine its efficacy in ameliorating BC-induced muscle fatigue, as well as its effects on transcriptomic, metabolomic, and lipidomic profiles in skeletal muscle. Methods: The pioglitazone and vehicle groups were treated orally for 4 weeks upon reaching a tumor volume of 600 mm3. Whole-animal indirect calorimetry was used to evaluate systemic metabolic states. The transcriptome was profiled using short-read bulk RNA sequencing (RNA-seq). Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to profile the metabolome and lipidome. Fast and slow skeletal muscle function were evaluated using isolated ex vivo testing. Results: Pioglitazone was associated with a 16.634% lower average O2 consumption (mL∙h−1, p = 0.035), 16.309% lower average CO2 production (mL∙h−1, p = 0.022), and 16.4% lower cumulative energy expenditure (EE) (kcal∙h−1, p = 0.035), with no changes in substrate utilization. RNA-seq supported the downstream effects of pioglitazone on target genes and displayed considerable upregulation of mitochondrial bioenergetic pathways. K-means cluster 5 showed enrichment of the PPAR signaling pathway (adj. p &lt; 0.05, Log2FC = 2.58). Skeletal muscle metabolomic and lipidomic profiles exhibited dysregulation in response to BC, which was partially restored in pioglitazone-treated mice compared to vehicle-treated BC-PDOX mice. In particular, the overall abundance of total ceramide levels was significantly lower in the PioTx group (−46.327%, p = 0.048). Despite molecular support for pioglitazone’s efficacy, isolated muscle function was not affected by pioglitazone treatment. No significant difference in the area under the fatigue curve (AUC) was found between the pioglitazone and vehicle groups (p = 0.596). Conclusions: BC induces multi-omic dysregulation in skeletal muscle, which pioglitazone partially ameliorates. Future research should focus on profiling systemic metabolic dysfunction, identifying molecular biomarkers of fatigue, and testing alternative pioglitazone treatment regimens.

Inhibition of ceramide de novo synthesis mitigates atherosclerosis

Abstract Background Atherosclerosis is the primary underlying cause of cardiovascular disease. Plasma ceramides are positively correlated with an increased risk of major adverse cardiovascular events and serve as an alternative biomarker for cardiovascular disease. Importantly, ceramide levels are notably higher within atherosclerotic plaques. Therefore, inhibiting the ceramide de novo synthesis pathway in the plaques may serve as a potential therapeutic intervention for atherosclerosis. Purpose We aim to assess the therapeutic efficacy of a nano-formulation of myriocin, a targeted inhibitor of serine-palmitoyl transferase, the key enzyme in ceramide de novo synthesis, in treating atherosclerosis. Methods Myriocin was encapsulated within the hydrophobic core of lipid-based nanoparticles specifically designed for this study. Male and female ApoE-/- mice, subjected to an 8-week high-fat diet regimen, received either myriocin nanoparticles (treatment group) or empty nanoparticles (control group) intravenously once a week for 4 weeks at a dose of 1.3 mg/kg body weight while still on the high-fat diet. At the study endpoint, whole aortas were harvested and subjected to Oil Red O staining to quantify the total lesion area. Histological staining was performed on serial sections of the aortic root to analyze the cellular composition within the plaques. Plasma samples were collected for total cholesterol measurement and lipidomic analysis. Results Upon intravenous administration, myriocin nanoparticles exhibited preferential accumulation in atherosclerotic plaques. Compared to control mice, those treated with myriocin nanoparticles exhibited a 58.7% reduction in total lesion area in male ApoE-/- mice and a 64.6% reduction in female ApoE-/- mice (p&amp;lt;0.0001). Consistently, the lesion areas in the aortic root were also reduced in the treated mice. Notably, myriocin nanoparticles enhanced collagen and alpha-smooth muscle content, while reducing macrophages and neutral lipids within the plaques, leading to a reduced plaque vulnerability index and preventing rupture events. TUNEL staining revealed reduced cellular apoptosis in the atherosclerotic plaques, resulting in a smaller necrotic area in the treated mice. In vitro experiments demonstrated that myriocin nanoparticles effectively inhibited lipopolysaccharide-induced inflammatory response and oxidative stress in bone marrow-derived macrophages. Furthermore, myriocin nanoparticles restored the gene expression of enzymes involved in the fatty acid beta-oxidation pathway, such as ACOX1 and CPT1A, in foam cells. Conclusion Using myriocin nanoparticles to inhibit excessive ceramide production due to inflammation reduces inflammation, and ROS production, while restoring fatty acid beta-oxidation in macrophages. This approach emerges as an effective strategy for targeting ceramide de novo synthesis within atherosclerotic plaques, thereby mitigating atherosclerosis progression and improving plaque stability.

Lipidomic profiling of serum and liver tissue reveals hepatoprotective mechanism of taxifolin in rats with CCl4-induced subacute hepatic injury based on LC-MS/MS

Currently, the hepatoprotective activity of taxifolin, a flavonoid isolated from Pseudotsuga taxifolia, has been reported in many animal models. However, whether the protective effect of taxifolin on the liver is related to its effect on lipidomics is unclear. Based on the significant therapeutic effect of taxifolin on CCl4 induced subacute hepatic injury, we observed the intervention of taxifolin by lipidomics. The results demonstrate that taxifolin can effectively reverse the damage caused by CCl4, which including hepatocyte vacuolization and necrosis. Lipomic profiling based on liquid chromatography-mass spectrometry showed that taxifolin was able to restore lipidomic changes caused by CCl4, including the levels of lysophosphatidylserine (LPS), phosphatidylcholine (PC), coenzyme (Co), phosphatidylglyceride (PG), phosphatidylserine (PS), dimethylphosphatidylethanolamine (dMePE), ceramide (Cer), sphingosine (So), triglycerides (TG), and monogalactosyl diacylglycerol (MGDG) in the rat liver, and phosphatidylcarbinol (PMe) and phosphatidylethanolamine (PE), plant sphingosine (phSM), glucose ceramide (CerG1), TG, and diglycerides (DG) in serum. Spearman's correlation analysis showed that CerG1, phSM, PE, and PMe in serum, and Cer, dMePE, PG, PS, So, TG, and MGDG in liver were positively correlated with serum levels of aspartate transaminase, alanine transaminase, and liver index; while TG, DG in serum, and Co, LPS, PC in liver were negatively correlated with the parameters. In total, 43 and 34 lipid molecules were altered by taxifolin treatment in the liver and serum, respectively, mainly including glycerophosphoglycerols, glycerophosphocholines, glycerophosphoethanolamines, and linoleic acids and derivatives. Our findings help to provide novel insights into the mechanism of the hepatoprotective effect of taxifolin from a lipidomics approach.

Plasma sphingomyelin levels were negatively correlated with ferritin levels in splenectomized thalassemia patients

Abstract Beta thalassemia results from decreased production of beta chains due to either mutations or deletions in the beta-globin gene, leading to impaired production of hemoglobin A. Thalassemia patients take frequent blood transfusions to compensate for hemolytic anemia and iron overload. Iron overload is monitored by serum ferritin levels in these patients. Extra-medullary hematopoiesis in beta thalassemia major leads to hypersplenism which often necessitates splenectomy to increase red cell life span and decrease transfusion need. Sphingomyelin is the second most abundant phospholipid in human plasma after phosphatidylcholine. In contrast to the well-defined roles of sphingolipids in cell membranes, their possible physiological role in lipoprotein metabolism has recently gained attention. Increased circulating levels of sphingomyelins and ceramides were observed in obesity, diabetes, and cardiovascular diseases. Although lipid abnormalities such as hypocholesterolemia and relatively increased triglycerides were reported in beta-thalassemia patients, there is no study investigating sphingolipid levels in thalassemia. Therefore, we investigate certain long chain and very long chain sphingomyelins and ceramides in beta-thalassemia patients who are under routine follow-up in our hospital. Thalassemia major patients who applied to the hospital for regular blood transfusion and gave consent were included in the study. Blood samples were obtained before transfusion. Plasma sphingomyelin (C16, C18 and C24) and ceramide (C16, C18, C20, C22, C24) species were measured by triple quadruple LC-ESI-MS/MS (Shimadzu, Japan). D-erythrosphingosine-D9 (Matreya) was used as an internal standard, all other lipid standards were from Avanti. Body iron stores of the patients were monitored by serum ferritin levels. A total of thirty patients were included in the study. All patients typically received regular erythrocyte suspension transfusions every three weeks and continuous oral iron chelation therapy. Twenty of the patients had a previous splenectomy. The mean age was 34.5 ±8.1 years in the splenectomy group and 32.8 ±8 years in the group without splenectomy. Mean ferritin levels were not different between the groups, being 1073.2±563.5 µg/L in splenectomy and 1709 ±1660.4 µg/L in non-splenectomy groups. All measured sphingolipid levels were similar between splenectomy and non-splenectomy groups. When correlation analysis was performed between measured sphingolipid and ferritin levels, significant negative correlations were found between sphingomyelin C16 (r= -0.591 p&amp;lt;0.006) and C18 (r= -0.594 p&amp;lt;0.006) with ferritin levels in the splenectomy group. However, this negative correlation was absent in the non-splenectomy group. In conclusion, we found that iron overload is associated with lower plasma sphingomyelin levels in splenectomized thalassemia patients. We have been working on the lipidomic analysis of the plasma and erythrocytes of thalassemia patients and other hemolytic anemias. The results may further help to get a better picture of lipid metabolism in thalassemia.

A sphingolipid rheostat controls apoptosis versus apical cell extrusion as alternative tumour-suppressive mechanisms

Evasion of cell death is a hallmark of cancer, and consequently the induction of cell death is a common strategy in cancer treatment. However, the molecular mechanisms regulating different types of cell death are poorly understood. We have formerly shown that in the epidermis of hypomorphic zebrafish hai1a mutant embryos, pre-neoplastic transformations of keratinocytes caused by unrestrained activity of the type II transmembrane serine protease Matriptase-1 heal spontaneously. This healing is driven by Matriptase-dependent increased sphingosine kinase (SphK) activity and sphingosine-1-phosphate (S1P)-mediated keratinocyte loss via apical cell extrusion. In contrast, amorphic hai1afr26 mutants with even higher Matriptase-1 and SphK activity die within a few days. Here we show that this lethality is not due to epidermal carcinogenesis, but to aberrant tp53-independent apoptosis of keratinocytes caused by increased levels of pro-apoptotic C16 ceramides, sphingolipid counterparts to S1P within the sphingolipid rheostat, which severely compromises the epidermal barrier. Mathematical modelling of sphingolipid rheostat homeostasis, combined with in vivo manipulations of components of the rheostat or the ceramide de novo synthesis pathway, indicate that this unexpected overproduction of ceramides is caused by a negative feedback loop sensing ceramide levels and controlling ceramide replenishment via de novo synthesis. Therefore, despite their initial decrease due to increased conversion to S1P, ceramides eventually reach cell death-inducing levels, making transformed pre-neoplastic keratinocytes die even before they are extruded, thereby abrogating the normally barrier-preserving mode of apical live cell extrusion. Our results offer an in vivo perspective of the dynamics of sphingolipid homeostasis and its relevance for epithelial cell survival versus cell death, linking apical cell extrusion and apoptosis. Implications for human carcinomas and their treatments are discussed.

Glycerophospholipid remodeling is critical for orthoflavivirus infection.

Flavivirus infection is tightly connected to host lipid metabolism. Here, we performed shotgun lipidomics of cells infected with neurotropic Zika, West Nile, and tick-borne encephalitis virus, as well as dengue and yellow fever virus. Early in infection specific lipids accumulate, e.g., neutral lipids in Zika and some lysophospholipids in all infections. Ceramide levels increase following infection with viruses that cause a cytopathic effect. In addition, fatty acid desaturation as well as glycerophospholipid metabolism are significantly altered. Importantly, depletion of enzymes involved in phosphatidylserine metabolism as well as phosphatidylinositol biosynthesis reduce orthoflavivirus titers and cytopathic effects while inhibition of fatty acid monounsaturation only rescues from virus-induced cell death. Interestingly, interfering with ceramide synthesis has opposing effects on virus replication and cytotoxicity depending on the targeted enzyme. Thus, lipid remodeling by orthoflaviviruses includes distinct changes but also common patterns shared by several viruses that are needed for efficient infection and replication.

Exploratory Analysis of the Association Between Plasma Ceramide Alterations and Cognitive Dysfunction in Parkinson's Disease.

Prior research has underscored the importance of sphingolipid metabolism in Parkinson's disease (PD) pathogenesis. Our objective was to explore the associations between plasma ceramide levels and PD patients with cognitive dysfunction (PD-CD). We enrolled two study populations from Eastern China and the Parkinson's Progression Markers Initiative (PPMI), comprising 290 (100 HCs, 160 PDs, and 30 MSAs) and 429 (125 HCs and 304 PDs) participants, respectively. The plasma levels of ceramides (Cer 16:0, Cer 18:0, Cer 24:0, and Cer 24:1) were tested via HPLC-MS/MS analysis. Compared with those in the HC group, the plasma levels of Cer 18:0, Cer 24:1, Cer 16:0/Cer 24:0, Cer 18:0/Cer 24:0, and Cer 24:1/Cer 24:0 were higher in both the PD and MSA groups. Significant differences in the plasma levels of Cer 16:0/Cer 24:0, Cer 18:0/Cer 24:0, and Cer 24:1/Cer 24:0 were observed among the PD-NC (PD with normal cognition), PD-MCI (PD with mild cognitive impairment), and PDD (PD dementia) groups, with the PDD group exhibiting the highest levels. PD patients with higher baseline levels of plasma ceramides (specifically, Cer 18:0, Cer 16:0/Cer 24:0, Cer 18:0/Cer 24:0, and Cer 24:1/Cer 24:0) demonstrated accelerated cognitive decline compared with individuals who had lower baseline plasma ceramide levels during the 5-year follow-up period. A biomarker panel including Cer 18:0/Cer 24:0 and Cer 24:1/Cer 24:0 could effectively differentiate PD-CD from PD-NC with notable diagnostic accuracy. Our results indicate that plasma ceramide levels could potentially be used as diagnostic biomarkers for PD-CD.

Age-dependent changes in visceral adiposity are associated with decreased plasma levels of DHEA-S in sigma-1 receptor knockout male mice

The sigma-1 receptor (S1R) is involved in intracellular lipid synthesis and transport. Recent studies have shown that its genetic inactivation impairs adipogenic differentiation in vitro. This study investigated the role of S1R in adipose tissue physiology and metabolic health using adult and old WT and S1R KO mice.Visceral fat mass was increased in adult, but not old S1R-KO male mice compared to that of WT mice, despite having similar body weights, food intake, and energy expenditure. The average adipocyte size was 64 % larger in adult KO mice than in adult WT mice. Adult S1R-KO mice showed reduced plasma dehydroepiandrosterone sulfate (DHEA-S) and elevated fasting plasma leptin concentrations. Lipidomic analysis revealed alterations in plasma metabolite concentrations, particularly reduced levels of sphingomyelins, ceramides, phosphatidylcholines, lysophosphatidylcholines, and cholesteryl esters in adult mice. Decreased expression of Pparγ, Adipoq, and Atgl was detected in visceral white adipose tissue (vWAT) isolated from adult KO mice. Additionally, Fabp4 and Adipoq expression levels were significantly lower in KO adipose-derived stromal cells than in WT adipose-derived stromal cells. A fivefold increase in the mitochondrial fatty acid oxidation rate and a 43 % increase in electron transfer coupling capacity were detected in adult S1R-KO vWAT.In summary, our investigation revealed an age-dependent association between increased visceral adiposity and decreased plasma levels of DHEA-S in S1R-deficient male mice. These findings underscore the potential role of S1R in regulating metabolic processes in adipose tissue and suggest that DHEA-S is a potential mediator of adiposity changes in the absence of S1R.

Impact of reduced hepatic ceramide levels in high-fat diet mice on glucose metabolism

Dysregulation of insulin action in hepatocytes, common in obesity, significantly contributes to insulin resistance, type 2 diabetes, and metabolic syndrome. Previous research highlights ceramides' role in these conditions. This study explores the impact of ceramides by silencing the serine palmitoyltransferase (Sptlc2) gene, crucial for the initial ceramide biosynthesis, using hydrodynamic gene delivery. Male C57BL/6 mice were randomly divided into three groups: one on a low-fat diet (LFD) receiving scrambled shRNA plasmids, another on a high-fat diet (HFD) with scrambled shRNA plasmids, and a third on HFD with a plasmid targeting Sptlc2. Analyses included RT-PCR for gene expression, western blot for protein levels, and UHPLC/MS/MS for lipid profiling. Glucose metabolism was evaluated via oral glucose tolerance tests, homeostatic model assessment of insulin resistance, and glucose-6-phosphate analysis. Results showed that HFD induces insulin resistance by inhibiting insulin signaling and increasing active lipid levels in hepatocytes. Sptlc2 silencing reduced ceramide accumulation, improving insulin signaling and glucose metabolism. Notably, ceramide synthesis inhibition did not significantly affect other lipid levels, highlighting ceramide's critical role in hepatic insulin resistance.

Oxidised phosphatidylcholine induces sarcolemmal ceramide accumulation and insulin resistance in skeletal muscle.

Intracellular ceramide accumulation in specific cellular compartments is a potential mechanism explaining muscle insulin resistance in the pathogenesis of type 2 diabetes. Muscle sarcolemmal ceramide accumulation negatively impacts insulin sensitivity in humans, but the mechanism explaining this localised accumulation is unknown. Previous reports revealed that circulating oxidised LDL is elevated in serum of individuals with obesity and type 2 diabetes. Oxidised phosphatidylcholine, which is present in oxidised LDL, has previously been linked to ceramide pathway activation, and could contribute to localised ceramide accumulation in skeletal muscle. We hypothesised that oxidised phosphatidylcholine inversely correlates with insulin sensitivity in serum, and induces sarcolemmal ceramide accumulation and decreases insulin sensitivity in muscle. We used LC-MS/MS to quantify specific oxidised phosphatidylcholine species in serum from a cross-sectional study of 58 well-characterised individuals spanning the physiological range of insulin sensitivity. We also performed in vitro experiments in rat L6 myotubes interrogating the role of specific oxidised phosphatidylcholine species in promoting sarcolemmal ceramide accumulation, inflammation and insulin resistance in skeletal muscle cells. Human serum oxidised phosphatidylcholine levels are elevated in individuals with obesity and type 2 diabetes, inversely correlated with insulin sensitivity, and positively correlated with sarcolemmal C18:0 ceramide levels in skeletal muscle. Specific oxidised phosphatidylcholine species, particularly 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine (POVPC), increase total ceramide and dihydroceramide and decrease total sphingomyelin in the sarcolemma of L6 myotubes by de novo ceramide synthesis and sphingomyelinase activation. POVPC also increases inflammatory signalling and causes insulin resistance in L6 myotubes. These data suggest that circulating oxidised phosphatidylcholine species promote ceramide accumulation and decrease insulin sensitivity in muscle, help explain localised sphingolipid accumulation and muscle inflammatory response, and highlight oxidised phosphatidylcholine species as potential targets to combat insulin resistance.

Ceramide As A Potential Tumor Marker For Diagnosis Of Prostate Cancer And Its Association With Lipid Profile

Background: Prostate cancer (PCa) is the second most frequent type of malignancy cancer among men worldwide. Ceramides are fatty acid derivatives of sphingoid bases, and formed not only through the de novo biosynthetic pathway, but also from the degradation of glycosphingolipids (GSLs) and ceramide-1-phosphate. Dyslipidaemia is part of metabolic syndrome, characterized by an alteration of the plasma lipid profile, including Cholesterol, HDL, and triglyceride levels. Objective Evaluate serum ceramide as tumer marker of prostate cancer and its association with lipid profile. Method This case- control study was carried out at Department of Biochemistry, College of Medicine, University of Baghdad and at Urology department, Ghazi Al-Hariri Hospital for surgical speciality during the period from March 2022 to May 2023. It included 120 men patients, 60 men patients who newly diagnosed to have primary prostate cancer (PCa), and 60 men were apparently healthy men. Investigations included serum measurements of ceramide by using enzyme linked immunosorbent assay(ELISA) and also measurement of lipid profile by using semi-auto biochemistry analyzer.Results The results of the present study showed that there was a significant differences in ceramide in prostate cancer patients as compared with the control group The results also showed that the S.Cholesterol, and S.Triglyceride were higher in the patients group compared to the controls group with significant statistical difference. Conclusion. According to the results obtained we can suggest that higher levels of ceramide, Cholesterol and Triglyceride may be associated with risk of prostate cancer.

Lipidomics Analysis of Human HMC3 Microglial Cells in an In Vitro Model of Metabolic Syndrome.

Metabolic endotoxemia (ME) is associated with bacterial lipopolysaccharide (LPS, endotoxin) and increased levels of saturated fatty acids (SFAs) in the bloodstream, causing systemic inflammation. ME usually accompanies obesity and a diet rich in fats, especially SFAs. Numerous studies confirm the effect of ME-related endotoxin on microglial activation. Our study aimed to assess lipid metabolism and immune response in microglia pre-stimulated with TNFα (Tumor Necrosis Factor α) and then with endotoxin and palmitic acid (PA). Using ELISA, we determined cytokines IL-1β, IL-10, IL-13 (interleukin-1β, -10, -13, and TGFβ (Transforming Growth Factor β) in the culture medium from microglial cells stimulated for 24 h with TNFα and then treated with LPS (10 ng/mL) and PA (200 µM) for 24 h. HMC3 (Human Microglial Cells clone 3) cells produced negligible amounts of IL-1β, IL-10, and IL-13 after stimulation but secreted moderate levels of TGFβ. Changes in lipid metabolism accompanied changes in TREM2 (Triggering Receptor Expressed on Myeloid Cells 2) expression. HMC3 stimulation with endotoxin increased TREM2 expression, while PA treatment decreased it. Endotoxin increased ceramide levels, while PA increased triglyceride levels. These results indicated that pre-stimulation of microglia with TNFα significantly affects its interactions with LPS and PA and modulates lipid metabolism, which may lead to microglial activation silencing and neurodegeneration.

Plasma Ceramide C24:0/C16:0 Ratio is Associated with Improved Survival in Patients with Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) has a high fatality rate, with surgery as the only curative treatment. Identification of new biomarkers related to survival may help guide discovery of new pathophysiologic pathways and potential therapeutic targets. As long-chain ceramides have been linked to tumor proliferation, we sought to determine if ceramide levels were prognostic in PDAC. Patients from two phase I studies of PDAC were followed for all-cause mortality. Ceramide levels (C24:0, C22:0, and C16:0) were quantified before treatment and at study intervals. Multivariable Cox regression models assessed the association of ceramide levels and mortality after adjusting for other univariable predictors, including time-dependent tumor resection. The ability of repeated ceramide measures to discriminate patients at risk for mortality was also assessed using multivariable modeling and the c-statistic. Higher plasma C16:0 concentration was associated with higher all-cause mortality in univariable and multivariable analysis (adjusted hazard ratio [aHR] 1.41, 95% confidence interval [CI] 1.09-1.82; p<0.01). In contrast, a higher plasma C24:0/C16:0 ratio was associated with lower all-cause mortality in multivariable analysis (aHR 0.69, 95% CI 0.49-0.97; p=0.032). Discrimination of mortality was significantly improved with the addition of either plasma C16:0 or C24:0/C16:0 levels, with optimal discrimination occurring using repeated measures of the C24:0/C16:0 ratio (c-statistic 0.73 vs. c-statistic 0.66; p<0.001). Higher plasma C16:0 and lower C24:0/C16:0 ratios are independently associated with mortality in PDAC and show an ability to improve discrimination of mortality in this deadly disease. Further studies are needed to confirm this association and evaluate this novel pathway for potential therapeutic targets.

A specific serum lipid signature characterizes patients with glycogen storage disease type Ia

Glycogen storage disease type Ia (GSDIa) is a rare, inherited glucose-6-phosphatase-α (G6Pase-α) deficiency-induced carbohydrate metabolism disorder. Although hyperlipidemia is a hallmark of GSDI, the extent of lipid metabolism disruption remains incompletely understood. Lipidomic analysis was performed to characterize the serum lipidome in patients with GSDIa, by including age- and sex-matched healthy controls and age-matched hypercholesterolemic controls. Metabolic control and dietary information biochemical markers were obtained from patients with GSDIa. Patients with GSDIa showed higher total serum lysophosphatidylcholine (Fold Change, (FC) 2.2, P < 0.0001), acyl-acyl-phosphatidylcholine (FC 2.1, P < 0.0001), and ceramide (FC 2.4, P < 0.0001) levels and bile acid (FC 0.7, P < 0.001), acylcarnitines (FC 0.7, P < 0.001), and cholesterol esters (FC 1.0, P < 0.001) than those of healthy controls, and higher di- (FC 1.1, P < 0.0001; FC 0.9, P < 0.01) and triacylglycerol (FC 6.3, P < 0.0001; FC 3.9, P < 0.01) levels than those of healthy controls and hypercholesterolemic subjects. Both total cholesterol and triglyceride values correlated with Cer (d16:1/22:0), Cer (d18:1/20:0), Cer (d18:1/20:0(OH)), Cer (d18:1/22:0), Cer (d18:1/23:0), Cer (d18:1/24:1), Cer (d18:2/22:0), Cer (d18:2/24:1). Total cholesterol also correlated with Cer (d18:1/24:0), Cer (d18:2/20:0), HexCer (d16:1/22:0), HexCer (d18:1/18:0), and Hex2Cer (d18:1/20:0). Triglyceridelevels correlated with Cer (d18:0/24:1). Alanine aminotransferase values correlated with Cer (d18:0/22:0), insulin with Cer (d18:1/22:1) and Cer (d18:1/24:1), and HDL with hexosylceramide (HexCer) (d18:2/23:0). These results expand on the currently known involvement of lipid metabolism in GSDIa. Circulating Cer may allow for refined dietary assessment compared with traditional biomarkers. Because specific lipid species are relatively easy to assess, they represent potential novel biomarkers of GSDIa.

The relationship between sphingomyelin and ceramide levels and soft neurological signs in ADHD.

Attention deficit hyperactivity disorder (ADHD), characterized by attention deficit, hyperactivity, and impulsivity, has recently been associated with lipid metabolism. In particular, the roles of sphingomyelin, ceramide, andgalactosylceramidase in the pathophysiology of ADHD are being investigated. This study aims to explore the relationship between sphingolipid metabolism markers and soft neurological signs (SNS) in children diagnosed with ADHD who are not undergoing medication treatment. A cross-sectional analysis was conducted on 41 children and adolescents aged 7-12 years diagnosed with ADHD and 39 neurotypically developing controls. Plasma levels of ceramide, sphingomyelin, and galactosylceramidase were measuredusing Enzyme-Linked Immunosorbent Assay (ELISA). SNS were assessed using the Physical and Neurological Examination for Soft Signs (PANESS). Statistical analyses included Student's t-tests, Mann-Whitney U tests, and Multivariate Analysis ofCovariance (MANCOVA), along with logistic regression analysis. Plasma levels of ceramide and sphingomyelin in children with ADHD showed significant differences compared to the neurotypically developing control group; however, there were no significant differences in galactosylceramidase levels between the two groups. Positive correlations were found between plasma levels of ceramide and sphingomyelin and the PANESS subscales F1 (Total Gait and Station) and F3 (Total Dysrhythmia). Additionally, logistic regression analysis indicated that high ceramide levels were positively associated with ADHD. This study underscores a significant association between alterations in sphingolipid metabolism (specifically increased levels of ceramide and sphingomyelin) and the presence of SNS in children with ADHD. These findings elucidate the potential role of sphingolipid metabolism in the pathophysiology of ADHD and provide suggestions for future therapeutic research targeting sphingolipid metabolism in the treatment of ADHD.