Ceramide Research Articles

OR03-05 Novel Lipidome Signature in Active Cushing Syndrome Revealed by UHPLC-MS Metabolomics

Background: Alterations in circulating amino acids, polyamines and acylcarnitines have been reported in patients with endogenous chronic hypercortisolism. However, lipid metabolites profiling and its interplay with the serum metabolome and degree of hypercortisolism in patients with active Cushing syndrome (CS) has not been previously assessed. Objective: To identify new metabolomic biomarkers associated with active CS. Methodology: Multiple UHPLC-MS platforms were used to analyze the metabolome of serum samples obtained from 25 patients with active endogenous CS and 25 controls subjects matched by propensity score (sex, BMI, T2D, DLP, HBP). Results: Metabolome of CS patients was deeply disrupted with 122 (27%) of the assessed metabolites significantly altered (p adj. <0.05) out of which 5 bile acids resulted with the highest perturbation (> 2-fold decrease). From the altered metabolites, 3 amino acids (AA), 2 acylcarnitines (ACs), 2 ceramides (CER) and 5 glycerophospholipids showed direction of effect independently associated with 24-h urinary free cortisol (MS) levels. A highly discriminant (AUC 96%) metabolome signature (n=59) characterized by lower levels of AA, ACs, polyunsaturated fatty acids (PUFA) and monoglycerophosphocolines (MGPC) together with increased levels of triacyclglycerols (TG), CER, diacylglycerophosphocholines (DGPC) and cholesteryl esters was identified and cross-validated (R2Y= 0.92, Q2Y= 0.68) using PLS-DA VIP scores >1.5. PUFA omega-6, and alanine, aspartate and glutamate metabolism resulted the most impacted canonical pathways (q-stat 19.7, 10.8 (p<0.001). Finally, topological network analysis detected 158 pairwise differential correlations (p <0.005, 10,000-fold permutation) between 141 metabolites due to CS where the acylPC (P-18:1/0:0) resulted a key metabolite in the network (betweenness =0.117 & closeness centrality =0.467). Conclusion: Active Cushing syndrome leads to a global proatherogenic shift in the circulating ceramides, glycerophospholipids and sphingolipids metabolites which are independently associated to the levels of urinary free cortisol being potential biomarkers of patients’ cardiovascular risk.

SUN-582 Effect of the Combination of Conjugated Estrogens and Bazedoxifene on Muscle and Serum Lipidome in Obese Postmenopausal Women: A Placebo-Controlled Randomized Pilot Trial

Background and Objectives: Menopause is characterized by estrogen deficiency and predisposes women to weight gain and metabolic disturbances including lipid abnormalities. Orally-administered estrogens increase high-density lipoprotein (HDL) and triglycerides (TG) cholesterol and decreases low-density lipoprotein (LDL) cholesterol levels. The increase in serum TGs is not well understood. The objective of this study was to assess the effect of CE/BZA on serum and skeletal muscle lipid species in obese postmenopausal women. Methods: Randomized double-blind crossover pilot trial in 8 obese postmenopausal women (53± 3 years, BMI 35.7±3.2 kg/m2) assigned to 8 weeks of CE/BZA or placebo with 8 weeks washout in between. At the end of each 8-week treatment period, intrahepatic and skeletal muscle lipids were measured by proton magnetic resonance spectroscopy (1H-MRS) while serum and skeletal muscle lipidomics were assayed by ultrahigh performance liquid chromatography/mass spectrometry (UHPLC/MS). Results: No treatment differences were observed in intrahepatic lipid, soleus intramyocellular lipid (IMCL) or extramyocellular lipid (EMCL) as well as tibialis anterior IMCL or EMCL.The serum metabolome and lipidome comprised a total of 2002 biochemicals. Treatment with CE/BZA was associated with higher levels of diacylglycerols (DAGs) and triacylglycerols (TAGs) composed of long-chain saturated fatty acids (SFA, palmitic C16:0 and arachidic C20:0), monounsaturated FAs (MUFA, palmitoleic C16:1, oleic C18:1 and ecosenoic C20:1), and polyunsaturated FAs (PUFA, linoleic C18:2, arachidonic C20:4, eicosapentaenoic C20:5, and docosahexaenoic C22:6) compared to placebo (all p<0.05). Treatment with CE/BZA was also associated with lower levels of several acylcarnitine species, which are markers of FA oxidation, including long-chain SFA (C14, C16 and C18), MUFA (C18:1 and C24:1) and PUFA (C18:2, C20:2 and C20:4). In addition, treatment with CE/BZA was associated with higher levels of phosphatidylcholines (PCs), phosphatidylinositols (PIs), phosphatidylethanolamines (PEs), sphingomyelins (SMs), and ceramides (CER), as well as lower levels of lysophophatidylcholines (LPCs). There were no treatment differences in carnitine or ketones levels. The skeletal muscle analysis comprised a total of 652 biochemicals, but unlike in serum, no significant treatment differences were observed in the skeletal muscle lipidome. Conclusions: Our lipidomic analysis supports a model in which CE/BZA (and likely all oral estrogens) increases hepatic de novo FA synthesis and esterification into TAGs for export into TAG-rich very low-density lipoproteins, as well as decreased FA oxidation, respectively. Although CE/BZA treatment inhibits FA oxidation, it is not associated with hepatic lipid accumulation as measured by MRS, or skeletal muscle lipid accumulation measured by MRS and lipidomics.

Experimental Activation of Endocannabinoid System Reveals Antilipotoxic Effects on Cardiac Myocytes.

Hypertension coincides with myocardial alternations in lipid (including sphingolipids) and glucose metabolism. The latest data indicate that accumulation of metabolically active lipids, especially ceramide (CER) and diacylglycerol (DAG) significantly influences intracellular signaling pathways along with inducing insulin resistance. Since, it was demonstrated that the endocannabinoid system (ECS) affects myocardial metabolism it seems to be a relevant tool in alleviating metabolic disturbances within the cardiac muscle due to hypertension. All designed experiments were conducted on the animal model of primary hypertension, i.e., spontaneously hypertensive rat (SHR) with chronic ECS activation by injections of fatty acid amide hydrolase (FAAH) inhibitor—URB597. Lipid analyses were performed using chromatography techniques (gas liquid, thin layer, and high performance liquid chromatography). Colorimetric and immunoenzymatic testes were applied in order to determine plasma concentrations of insulin and glucose. Total myocardial expression of selected proteins was measured by Western blotting and/or immunohistochemistry methods. SHRs exhibited significantly intensified myocardial de novo pathway of CER synthesis as well as DAG accumulation compared to the control Wistar Kyoto rats. Besides, intramyocardial level of potentially cardioprotective sphingolipid, i.e., sphingosine-1-phosphate was considerably decreased in SHRs, whereas URB597 treatment restored the level of this derivative. Unexpectedly, ECS upregulation protected overloaded cardiac muscle against CER and DAG accumulation. Moreover, chronic URB597 treatment improved intramyocardial insulin signaling pathways in both normotensive and hypertensive conditions. It seems that the enhanced ECS triggers protective mechanisms in the heart due to decreasing the level of lipid mediators of insulin resistance.

Interaction between nitric oxide and storage temperature on sphingolipid metabolism of postharvest peach fruit

Both nitric oxide (NO) and cold storage have positive effects on the maintenance of fruit quality during storage. However, the roles of NO and storage temperatures in regulating the responses of sphingolipids metabolism to chilling injury of peach fruit during storage remain unknown. Peaches were treated by immersion in distilled water and 15 μmol L−1 NO solution, then stored at 25 °C and 0 °C, respectively. The effects of NO-treatment and storage temperature on the activities of enzymes in sphingolipid metabolism and the contents of sphingolipids in peach fruits were studied. NO maintained higher activities of acid phosphatase (AP) and alkaline phosphatase (ALP) in peach fruits at 25 °C, but promoted the decrease in the activities of AP and ALP at 0 °C, suggesting the regulation by NO on AP and ALP could be modulated by temperature. Compared with the storage at 25 °C, cold storage at 0 °C decreased the activities of phospholipase A (PLA), alkaline phosphatase (ALP), 3-ketodihydrosphingosine reductase (KDSR), sphingosine kinase (SPHK), ceramide synthase (CERS), ceramide kinase (CERK), and the contents of sphingosine (SPH), ceramide (CER), sphingosine-1-phosphate (S1P), ceramide-1-phosphate (C1P), sphingomyelin (SM), and increased the activities of phospholipase C (PLC), phospholipase D (PLD), sphingomyelin synthase (SMS). NO significantly increased the contents of sphingolipid metabolites, and the activities of PLA, KDSR, SPHK, CERS, CERK, but decreased the activities of PLC, PLD, SMS of peaches. The results suggested that NO could maintain sphingolipid metabolism to relieve the response of the postharvest fruit to low temperature.

Multiscale study on the enhancing effect and mechanism of borneolum on transdermal permeation of drugs with different log P values and molecular sizes.

D-borneolum is commonly used as a permeation enhancer in Traditional Chinese Medicine (TCM) formulas for transdermal application. Additionally, two other sources of borneolums were recorded in the 2015 edition of the Chinese Pharmacopoeia (ChP), including L-borneolum and borneolum syntheticum. To guide the selection and application of borneolum, the safety and enhancing effect of three sources of borneolums were investigated on transdermal permeation of compounds with different octanol-water partition coefficient (log P) values and molecular weights (MWs). Both the results of cellular cytotoxicity and in vitro transdermal permeation experiments showed that all three sources of borneolums could be applied in TDDS as permeation enhancers. Moreover, all three sources of borneolums achieved optimal permeation-enhancing performances on transdermal drugs with lower log P values as well as higher MWs. Further study was carried out to elucidate the potential molecular mechanism of borneolum enhancing transdermal drug delivery via transmission electron microscope (TEM) and coarse-grained molecular dynamic (CG-MD) simulation. Borneolum significantly promoted transdermal delivery of drugs via changing the dense morphology of the stratum corneum (SC), disturbing the ordered arrangement of ceramide (CER) and free fatty acid (FFA) molecules in lipid layers, and further increasing the diffusion rate of drugs in the lipid layers.

Development of an in vitro submerged culture system to synthesize epidermal ceramides in canine keratinocytes

Ceramides (CERs) in the stratum corneum (SC) are known to play a crucial role in determining skin barrier function in dogs. We aimed to develop an in vitro culture system that synthesized epidermal CER classes to better understand the synthesis of CER classes in canine SC–. Canine keratinocyte cells (MSCEK) at appropriate confluency were incubated with high Ca2+ (1.8 mM CaCl2) supplemented serum-free medium. Eight days post Ca2+ application, the surface of cultured MSCEK was broadly stained with anti-loricrin antibody implying that the keratinocytes had stratified into stratum granulosum. MSCEK cells synthesized heterogenous epidermal CERs, similar to those seen during the stratification of canine keratinocytes. CER fractions obtained from MSCEK cells were comparable to those from canine SC, including CER[EOS] (combination of ω-hydroxy fatty acids and sphingosines), CER[NP] (combination of non-hydroxy fatty acids and phytosphingosines), and CER[EOP] (combination of ω-hydroxy fatty acids and phytosphingosines), all of which are lowered in the SC during canine atopic dermatitis. Thus, the present study provides a simple culture system as a tool for in-depth analysis of CER production in canine keratinocytes.

Acid sphingomyelinase deficiency exacerbates LPS‐induced experimental periodontitis

Mutation of the gene for acid sphingomyelinase (ASMase) causes Niemann-Pick disease. However, the effect of ASMase deficiency on periodontal health is unknown. Periodontal disease is a disease resulting from infection and inflammation of periodontal tissue and alveolar bone that support the teeth. The goal of this study was to determine the role of ASMase deficiency in periodontal inflammation and alveolar bone loss. We induced periodontitis in wild-type and ASMase-deficient (ASMase-/- ) mice with periodontal lipopolysaccharide (LPS) injection and compared the alveolar bone loss and periodontal inflammation between these mice. Results showed that ASMase deficiency did not significantly change metabolic parameters, but exacerbated LPS-induced alveolar bone loss, osteoclastogenesis, and periodontal tissue inflammation. To understand the mechanisms by which ASMase deficiency aggravates LPS-induced periodontitis, we analyzed sphingolipids in periodontal tissues. Results showed that ASMase deficiency led to increases in not only sphingomyelin, but also ceramide (CER), a bioactive sphingolipid known to promote inflammation. Results further showed that ASMase deficiency increased CER de novo synthesis. ASMase deficiency exacerbated LPS-induced alveolar bone loss and periodontal inflammation. ASMase deficiency leads to an unexpected CER increase by stimulating de novo synthesis CER, which is likely to be involved in the ASMase deficiency-exacerbated periodontitis.

Cannabinoid Receptor Agonist WIN55, 212-2 Adjusts Lipid Metabolism in a Rat Model of Cardiac Arrest.

The objective of this study was to investigate the effects of pharmacologically induced hypothermia with WIN55, 212-2 (WIN)on postresuscitation myocardial function, microcirculation, and metabolism-specific lipids in a rat cardiac arrest (CA) model. Ventricular fibrillation was electrically induced and untreated for 6 minutes in 24 Sprague-Dawley rats weighing 450-550 g. Cardiopulmonary resuscitation including chest compression and mechanical ventilation was then initiated and continued for 8 minutes, followed by defibrillation. At 5 minutes after restoration of spontaneous circulation (ROSC), animals were randomized into four groups: (1) normothermia with vehicle (NT); (2) physical hypothermia with vehicle (PH); (3) WIN55, 212-2 with normothermia (WN); and (4) WIN55, 212-2 with hypothermia (WH). For groups of WN and WH, WIN was administered by continuous intravenous infusion with a syringe pump for 4 hours. PH started at 5 minutes after resuscitation. NT maintained core temperature at 37°C ± 0.2°C with the aid of a heating blanket. Hypothermia groups maintained temperature at 33°C ± 0.5°C for 4 hours after ROSC. There was a significant improvement in myocardial function as measured by ejection fraction, cardiac output, and myocardial performance index in animals treated with WH and PH beginning at 1 hour after start of infusion. In the WH and PH groups, buccal microcirculation was significantly improved compared with NT and WN. Plasma at pre-CA and ROSC 4 hours was harvested for lipid metabolism. The WH group appeared to be closer to baseline than the other groups in lipid metabolism. lysophosphatidylcholine (LPC) 18:2, free fatty acid (FFA) 22:6, and ceramide (CER) (24:0) changed significantly among the lipidomic data compared with NT (p < 0.05). Postresuscitation hypothermia improved myocardial function and microcirculation. WH-mediated lipid metabolism had the best metabolic outcome to bring back the animals to normal metabolism, which may be protective to improve outcomes of CA. LPC 18:2, FFA 22:6, and CER (24:0) may be important predictors of outcomes of CA.

Release of Ceramide Molecules from Ceramide-Containing UV-curable Acrylic Adhesive Gel Sheet Affixed to Human Skin

Ceramide, an intercellular lipid of the stratum corneum, plays an essential role in making the skin barrier. One problem with the use of medical adhesive tape or sheets for skin is that their repeated attachment and detachment may cause some damage to the skin. An attempt has been made to eliminate this problem by mixing ceramide into the adhesive of sheets, and has delivered excellent clinical results. This study aimed to investigate whether ceramide is transferred from the adhesive with added ceramide to the skin. An adhesive sheet was prepared by adding synthetic ceramide (CER) to UV-curable acrylic adhesive gel. After affixing the adhesive sheet to human skin for a certain period, it was peeled off and cut perpendicular to the adhesive surface. Synchrotron micro-infrared spectroscopy of the sectioned samples showed that the ceramide concentration in the gel sheet decreases as the application time to human skin increases. This is thought to be due to the release of CER from the gel sheet.

Molecular mechanism of the skin permeation enhancing effect of ethanol: a molecular dynamics study

Ethanol is widely used in various pharmaceutical and cosmetic formulations in order to enhance skin penetration of active ingredients. While it is well known that ethanol partitions into the skin and enhances the permeation of both polar and nonpolar molecules, the exact mechanisms by which it enhances skin permeability are not fully understood. Several mechanisms have been proposed including lipid extraction from the stratum corneum (SC), fluidisation of SC lipid bilayer, alteration of SC protein conformation and enhancement of the drug solubility in the SC lipids. In this study, we performed molecular dynamics (MD) simulations of SC lipid bilayers comprised of an equimolar mixture of ceramides, cholesterol and free fatty acid in the presence of aqueous mixtures of ethanol. Various unrestrained MD simulations were performed in the presence of aqueous ethanol solution at molar ratios (x) ranging from x = 0 to x = 1. It was found that ethanol enhances bilayer permeability by dual actions (a) extraction of the skin lipids and (b) enhancing the mobility of lipid chains. Ethanol's permeation enhancing effect arises from its superior ability to form hydrogen bonds with headgroup atoms of skin lipids. Further, the free energy of extraction of ceramides (CER) and fatty acids (FFA) from the lipid bilayer was studied using umbrella sampling simulations. The free energy of extraction of CER was found to be much higher compared to FFA for all ethanol concentrations which shows that CER are difficult to extract as compared to FFA. Finally, the permeation of benzoic acid drug molecules through the skin lipid bilayer is shown in presence of ethanol molecules. It was found that ethanol selectively targets the FFA of the skin lipid bilayer and extracts it out of the lipid bilayer within few microseconds. Further, ethanol penetrates inside the lipid layer and creates the channels from which drug molecules can easily cross the lipid layer. Our observations (both in unrestrained and umbrella sampling simulations) are consistent with the experimental findings reported in the literature. The simulation methodology could be used for design and testing of permeation enhancers (acting on skin SC lipid lamella) for topical and transdermal drug delivery applications.

Engineering water-induced ceramide/lecithin oleogels: understanding the influence of water added upon pre- and post-nucleation.

A mixture of ceramide (CER) and lecithin (LEC) at specific ratios was capable of forming oleogels in sunflower oil triggered by adding a trace amount of water. It was noted that the addition of water at different temperatures (TW) resulted in different gelation behaviors and microstructures. To better illuminate the assembly mechanism at different TW, samples with water added at different TW (20 °C, 45 °C, 70 °C and 95 °C) were prepared. The viscoelastic properties, microstructures, and the crystal packing of these samples were investigated. It was observed that all samples prepared at TW of 20 °C and 95 °C formed gels, while most samples prepared at TW of 45 °C and 70 °C were too weak to form gels. Gels prepared at 95 °C were stronger but more fragile in texture compared to gels produced at 20 °C. The crystal morphology of gels drastically changed with TW. Spindle-shaped crystals were observed in gels prepared at low TW (20 °C), while gels prepared at high TW (95 °C) exhibited a network with packed oil droplets stabilized by lamellar shells together with fibrillar crystals in the bulk phase. X-ray diffractograms showed a different reflection peak (d-spacing of 14.5 Å) in gel prepared at 20 °C, compared to the d-spacing in oleogels with a single gelator (13.14 Å and 15.33 Å, respectively, for CER and LEC). Gel prepared at 95 °C showed two long-spacing characteristic peaks, which correspond to the characteristic peaks of CER gel (∼13 Å) and LEC gel (∼12 Å). Fourier transform infrared spectroscopy results indicated that the different gelation behaviors at different TW were mainly caused by vibrational changes in the amide bond of CER. Our hypothesized assembly mechanism can be concluded as: increasing TW resulted in the conversion of CER and LEC crystallization from co-assembly (TW = 20 °C) to self-sorting by individual gelators (TW = 95 °C). In this study, novel water-induced oleogels were produced by manipulating TW, and such information further assists the rational design of lipid-based healthy fat products.

Lack of glutathione peroxidase-8 in the ER impacts on lipid composition of HeLa cells microsomal membranes

GPx8 is a glutathione peroxidase homolog inserted in the membranes of endoplasmic reticulum (ER), where it seemingly plays a role in controlling redox status by preventing the spill of H2O2. We addressed the impact of GPx8 silencing on the lipidome of microsomal membranes, using stably GPx8-silenced HeLa cells. The two cell lines were clearly separated by Principal Component Analysis (PCA) and Partial Least Square Discriminant analysis (PLS-DA) of lipidome. Considering in detail the individual lipid classes, we observed that unsaturated glycerophospholipids (GPL) decreased, while only in phosphatidylinositols (PI) a substitution of monounsaturated fatty acids (MUFA) for polyunsaturated fatty acids (PUFA) was observed. Among sphingolipids (SL), ceramides (CER) decreased while sphingomyelins (SM) and neutral glycophingolipids (nGSL) increased. Here, in addition, longer chains than in controls in the amide fatty acid were present. The increase up to four folds of the CER (d18:1; c24:0) containing three hexose units, was the most remarkable species increasing in the differential lipidome of siGPx8 cells.Quantitative RT-PCR complied with lipidomic analysis specifically showing an increased expression of: i) acyl-CoA synthetase 5 (ACSL5); ii) CER synthase 2 and 4; iii) CER transporter (CERT); iv) UDP-glucosyl transferase (UDP-GlcT), associated to a decreased expression of UDP-galactosyl transferase (UDP-GalT). A role of the unfolded protein response (UPR) and the spliced form of the transcription factor XBP1 on the transcriptional changes of GPx8 silenced cells was ruled-out. Similarly, also the involvement of Nrf2 and NF-κB.Altogether our results indicate that GPx8-silencing of HeLa yields a membrane depleted by about 24% of polyunsaturated GPL and a corresponding increase of saturated or monounsaturated SM and specific nGSL. This is tentatively interpreted as an adaptive mechanism leading to an increased resistance to radical oxidations. Moreover, the marked shift of fatty acid composition of PI emerges as a possibly relevant issue in respect to the impact of GPx8 on signaling pathways.

Improvement of the Skin Barrier Function with Physiologically Active Substances

Intercellular lipids in the stratum corneum (SC), including ceramides (CERs), cholesterol, and fatty acids, are important for maintaining the skin barrier function. CERs in the SC have vital roles in water retention and the barrier function. A decrease in intercellular lipids, however, reduces the skin barrier function. In this study, the ability of CER precursors to increase the level of CERs in the SC and improve the skin barrier function was examined. Glucosylceramide and sphingomyelin liposomes were used as CER precursors and prepared with a thin-film method. The particle diameter and surface potential of glucosylceramide liposomes were 120.0 nm and -20 mV, while those of sphingomyelin liposomes were 153.3 nm and -11.4 mV, respectively. Transmission electron microscopy images showed that both liposomes were closed vesicles having a lamellar structure. These liposomes were applied from the SC side of a three-dimensional cultured human epidermis model, and the level of CERs in the epidermis was measured by high-performance thin-layer chromatography. In this study, the application of glucosylceramide or sphingomyelin liposomes increased the amount of CERs. In addition, the precursors of CERs were effective in improving the skin barrier function.

Barrier Capability of Skin Lipid Models: Effect of Ceramides and Free Fatty Acid Composition.

The skin is an effective barrier that prevents the influx of harmful substances from the environment and the efflux of body fluid. This barrier function is ascribed to the intercellular lipids present in the outermost layer of the skin referred to as the stratum corneum (SC). These lipids are composed mainly of ceramides (CERs), cholesterol, and free fatty acids (FFAs). Alterations in the SC lipid composition and barrier function impairment occur in several skin diseases including atopic dermatitis (AD). As the etiology of AD is multifactorial, establishing the relationship between the changes in SC lipid composition and barrier function impairment in the patients remains a challenge. Here, we employed model membrane systems to investigate the contribution of various anomalies in the SC CER and FFA composition observed in AD patients' skin to the barrier dysfunction. Using ethyl-p-aminobenzoate permeation and transepidermal water loss values as markers for barrier function, we determined that the alterations in SC lipid composition contribute to the impaired barrier function in AD patients. By the use of biophysical techniques, we established that the largest reduction in barrier capability was observed in the model with an increased fraction of short-chain FFAs, evident by the decrease in chain packing density. Modulations in the CER subclass composition impacted the lamellar organization while having a smaller effect on the barrier function. These findings provide evidence that AD therapies normalizing the FFA composition are at least as important as normalizing CER composition.

Circulating Lysophosphatidylcholines, Phosphatidylcholines, Ceramides, and Sphingomyelins and Ovarian Cancer Risk: A 23-Year Prospective Study.

Experimental evidence supports a role of lipid dysregulation in ovarian cancer progression. We estimated associations with ovarian cancer risk for circulating levels of four lipid groups, previously hypothesized to be associated with ovarian cancer, measured 3-23 years before diagnosis. Analyses were conducted among cases (N = 252) and matched controls (N = 252) from the Nurses' Health Studies. We used logistic regression adjusting for risk factors to investigate associations of lysophosphatidylcholines (LPCs), phosphatidylcholines (PCs), ceramides (CERs), and sphingomyelins (SMs) with ovarian cancer risk overall and by histotype. A modified Bonferroni approach (0.05/4 = 0.0125, four lipid groups) and the permutation-based Westfall and Young approach were used to account for testing multiple correlated hypotheses. Odds ratios (ORs; 10th-90th percentile), and 95% confidence intervals of ovarian cancer risk were estimated. All statistical tests were two-sided. SM sum was statistically significantly associated with ovarian cancer risk (OR = 1.97, 95% CI = 1.16 to 3.32; P = .01/permutation-adjusted P = .20). C16:0 SM, C18:0 SM, and C16:0 CERs were suggestively associated with risk (OR = 1.95-2.10; P = .004-.01; permutation-adjusted P = .08-.21). SM sum, C16:0 SM, and C16:0 CER had stronger odds ratios among postmenopausal women (OR = 2.16-3.22). Odds ratios were similar for serous/poorly differentiated and endometrioid/clear cell tumors, although C18:1 LPC and LPC to PC ratio were suggestively inversely associated, whereas C18:0 SM was suggestively positively associated with risk of endometrioid/clear cell tumors. No individual metabolites were associated with risk when using the permutation-based approach. Elevated levels of circulating SMs 3-23 years before diagnosis were associated with increased risk of ovarian cancer, regardless of histotype, with stronger associations among postmenopausal women. Further studies are required to validate and understand the role of lipid dysregulation in ovarian carcinogenesis.

Ceramide system contributes to learning and memory

Ceramide system contributes to learning and memory

Recent Advances on Topical Application of Ceramides to Restore Barrier Function of Skin

Human skin is the largest organ of the body and is an effective physical barrier keeping it from environmental conditions. This barrier function of the skin is based on stratum corneum, located in the uppermost skin. Stratum corneum has corneocytes surrounded by multilamellar lipid membranes which are composed of cholesterol, free fatty acids and ceramides (CERs). Alterations in ceramide content of the stratum corneum are associated with numerous skin disorders. In recent years, CERs have been incorporated into conventional and novel carrier systems with the purpose of exogenously applying CERs to help the barrier function of the skin. This review provides an overview of the structure, function and importance of CERs to restore the barrier function of the skin following their topical application.

Simplified Mass Spectrometric Analysis of Ceramides using a Common Collision Energy.

Ceramides (CER) are biologically active sphingolipid precursors that are mechanistically linked to several pathogenic states including cancer, insulin resistance, and neurodegeneration. CER are commonly quantified through mass spectrometry-based methods founded upon a product ion scan (PIS) in positive mode to produce a characteristic m/z 264 ion. The ionization efficiency (IE) of CER species decreases with an increase in CER mass, thus quantitation of CER typically involves application of mass-dependent response factors (RF) for each CER species. In this work, we observed that the RF were systematically dependent on the number of fatty acid acyl carbons and the collision energy (CE) used to generate the m/z 264 ion. Using these complimentary trends, we determined an "isosbestic" CE where the RF for all CER species were equivalent, allowing for CER quantitation without postcollection correction factors. A comparison of this common CE/common RF method to the multiple RF method demonstrated good agreement between the two methods. Use of the common CE/common RF method will reduce data processing and reduce the use of multiple CER species standards.

Serum fatty acid binding proteins as a potential biomarker in atrial fibrillation.

Atrial fibrillation (AF) is a commonly occurring arrhythmia which significantly reduces patients' quality of life and substantially shortens life expectancy. Although long chain fatty acids (LCFAs) are the basic energy substrates for myocardial metabolism, their excess can result in lipotoxicity, which increases the risk of arrhythmia. Intracellularly, LCFAs are bound by fatty acid biding proteins (FABPs) and this results in low level of free LCFAs in the cytoplasm. Based on this principle, FABPs are considered "safeguards" against overwhelming accumulation of esterified into different bioactive lipid fractions (e.g. ceramide, diacylglycerols) LCFAs. So far, several FABPs have been discovered in humans. Currently, in relation to cardiovascular diseases heart-type fatty acid binding protein (H-FABP) and adipocyte fatty acid binding protein (A-FABP) play significant roles. Nowadays, A-FABP is of great interest for research related with obesity, diabetes and coexisting disorders including cardiovascular diseases. Concomitantly, H-FABP is already well-established marker in the early diagnosis of myocardial infarction. Moreover, FABPs were assigned as a potential biomarker of AF in patients with de novo diagnosed arrhythmia, chronic heart failure (CHF), and in patients undergoing cardiac surgery. Another group of studies where the concentrations of plasma FABPs were analyzed are patients subjected to electrical cardioversion (ECV) and radio-catheter ablation therapy (RFA). It is worth mentioning that, in addition to traditional anti-arrhythmic drugs (AADs) or ECV, ablation techniques are used with good effects. Even though the treatment of arrhythmias is constantly developing, the maintenance of the sinus rhythm (SR) is still a serious problem. Therefore, it is worth looking for a biomarker which is suitable for the patient's treatment qualifications as well as assessing its effectiveness. Thus, the aim of this work is to present current data on the clinical significance of FABPs in terms of the development and treatment of AF.

1900-P: Very Low-Density Lipoprotein Ceramides and Hepatic Lipid Accumulation

Ceramides (CER) have been implicated, along with other lipotoxic lipids (diacylglycerols, triacylglycerols, TG) that play important roles in the development and progression of nonalcoholic fatty liver disease (NAFLD). No study to date has measured CER in very low-density lipoproteins (VLDL), along with other lipids from obese men with characteristics of the metabolic syndrome. Twelve subjects with metabolic abnormalities that put them at risk for NAFLD (mean±SD, age 42.1±5.4y, BMI 37.8±3.5 kg/m2, ALT 45±21 U/L) were studied. VLDL particles were isolated in the fasted state and CER measured via UPLC-MS/MS analysis. VLDL-apoB100 was measured by ELISA and intrahepatic triglycerides (IHTG) analyzed by MRS. Total VLDL-CER were positively correlated with both VLDL-TG (r = 0.572, P=0.004) and VLDL-apoB100 (r = 0.557, P=0.005). CER were negatively correlated with IHTG (r = -0.447, P= 0.02), as was VLDL-TG concentration (r = -0.551, P=0.006). These data suggest that CER and TG are packaged together in the liver and secreted on VLDL particles, and do not support the addition of CER to particles after they have been secreted. In these relatively healthy men, the data support the concept that liver lipid secretion is associated with a decreased risk for fat accumulation in the liver. An excretion of lipotoxic lipids like TG and CER in VLDL can protect the liver from excess lipid accumulation. Disclosure J.M. Mucinski: None.