Sphingomyelin Content Research Articles

Contents and composition of individual phospholipid classes from biceps femoris related to the rearing system in Iberian pig

During dry-cured ham processing, phospholipids (PL) are the main substrates of lipolysis and oxidation. However, the published data on individual PL classes in the pig muscle are inconsistent. This study determined the PL class contents and composition in biceps femoris of Iberian pigs according to the rearing system (Montanera vs Pienso). Phosphatidylcholine (PC), phosphatidylethanolamine (PE), cardiolipin (CL) and sphingomyelin contents were higher in the Montanera pigs than in the Pienso pigs. Total PL and PC, PE, phosphatidylinositol + phosphatidylserine and CL contained higher levels of oleic acid and slightly higher levels of n-3 polyunsaturated fatty acids (PUFA) but lower levels of n-6 PUFA in the Montanera pigs than in the Pienso pigs. The rearing system had no effect on the plasmalogen content but influenced aldehyde composition, mainly in PE and in total PL. These results can partially explain the differences in sensory properties of dry-cured ham between the Montanera and Pienso systems.

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

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. 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. 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. 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. 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.

Effect of lipid on surimi gelation properties of the three major Chinese carp.

Gel properties are important in determining the quality of surimi. In addition to myofibrillar proteins, lipids play an important role in the formation of surimi gel. Phospholipids (PL) are amphoteric lipids that cannot be removed through rinsing. Paradoxically, the addition of PL increases or decreases gel strength. This research aimed to investigate the effects of specific lipids on the gelation properties of surimi from three different carp. The hardness, chewiness, and gel strength of bighead carp (Aristichthys nobilis: BC) surimi were higher, and the total lipid content was lower when compared with grass carp (Ctenopharyngodon idellus: GC) and silver carp (Hypophthalmichthys molitrix: SC) surimi. Bighead carp surimi had lower levels of phosphatidylethanolamine (PE), phosphatidylinositols (PI), and phosphatidylcholine (PC), and higher phosphatidylserine (PS) and sphingomyelin (SM) content. The gelation properties of surimi increased with increasing concentrations of SM and PS. Furthermore, increased levels of saturated fatty acids (SFAs) and decreased levels of polyunsaturated fatty acids (PUFAs) increased gelation properties. Finally, higher hydrophobic interactions and more disulfide bonds were shown to increase gel network structure stability, resulting in improving gel strength in BC surimi. The textural characteristics and gel strength of surimi were dependent on the PL content, including total lipid levels and the types of fatty acids. This may account for previous conflicting reports on PL effects on gel strength. This study provides insight into how the texture of surimi can be improved and provides a starting point for further research. © 2020 Society of Chemical Industry.

Lipid Profiling and Microstructure Characteristics of Goat Milk Fat from Different Stages of Lactation.

Goat milk at different lactations show varied lipids distributions, which are potentially dietary influencing factors for the health of human consumers. Herein, the effects of lactation stages (colostral, transitional, and mature stages) on lipid profiling and microstructure of goat milk fat (GMF) were investigated. A total of 359 species of triacylglycerols (TAGs), 27 species of diacylglycerols (DAGs), and 10 classes of phospholipids (PLs) were identified using high resolution tandem mass spectrometry (HR-MS/MS). Of importance, goat transitional milk presented the highest levels of MUFA (29.51%) and lyso-phospholipids (7.95% of total PLs) among these three different lactations. A lactation-dependent attenuation was found at the level of PUFA in goat milk, particularly long-chain PUFA ω-6. Similar behavior was observed in the total proportions of POO (16:0/18:1/18:1) and PSL (16:0/18:0/18:2), presenting a decrease from 3.70% to 3.23% as the proceeding period from colostrum to mature. The relative contents of sphingomyelin and cholesterol in goat colostrum were approximately twice and three times that in mature milk, respectively. Unlikely, both PMCy+MCaM (16:0/14:0/8:0 + 14:0/10:0/14:0) and BuPO (4:0/16:0/18:1) TAGs, the foremost saturated and monounsaturated TAGs in goat colostrum, respectively, showed upward trends over the period from colostrum to mature. Interestingly, no significant variation in milk fat globule morphology was monitored at different lactation periods. Therefore, all our results demonstrated that the main influences of lactation stages on GMF were the lipid profiling, providing a theoretical guidance for rational implement of lipids in goat milk.

M10. SERUM AND CLINICAL MARKERS ASSOCIATED WITH MEMBRANE PUFA CONTENT IN A POPULATION OF STABILISED AND TREATED SCHIZOPHRENIA OUTPATIENTS

BackgroundVarious candidate biomarkers have been proposed in schizophrenia to better characterise the several forms of the disorder. Among these candidates, peripheral (e.g. immunological, inflammatory, microbial) and brain (structural and functional) factors have been suggested and could help subtyping schizophrenia. One other potential biomarker, the membrane polyunsaturated fatty acid (PUFA) content, has been described both in peripheral cells and brain membranes of patients. Increased symptom severity along with more severe cognitive impairment were shown to be associated with decrease in the red blood cell (RBC) membrane sphingomyelin and PUFA content. However, little is known regarding the association between this membrane biomarker and serum related ones.The results presented here are preliminary and come from a study examining clinical and cognitive symptoms, RBC total membrane fatty-acid (FA) content, and serum biomarkers in a population of schizophrenia patients.We hypothesised that the sub-group of patients with decreased membrane PUFA content will also exhibit a higher incidence of abnormalities in some other serum biomarkers in comparison with patients with normal membrane PUFA content.MethodsA population of 33 chronic, medicated, and clinically stable patients with schizophrenia gave their informed consent for a study examining in particular their medical, psychiatric, and treatment history. The other measures assessed psychopathology (PANSS, CGI, Calgary scale), functioning and quality of life (GAF, SF36), and cognition (MOCA, MCST). Various biological biomarkers - in particular those related to inflammation, immunity, energy and hormone metabolism - were also examined. The total RBC membrane FA content was also measured using GC-FID (Gas Chromatography–Flame-Ionization Detection).ResultsBased on the standard values of the docosohexaenoic acid (DHA) (expressed as percentage of total fatty acids) in the RBC lipid membrane, a subgroup of 18 patients exhibited an abnormal decrease in DHA content (DHA-), while the remaining 15 individuals had DHA value within the normal range (DHAn). DHA- and DHAn groups were compared using univariate analysis in terms of other clinical and biological associated characteristics.We could also demonstrate a decrease in total membrane PUFAs in the DHA- group (p=0.004). Of interest, serum IL-6 was significantly (p=0.02) increased in the DHA- population. There was also a trend in favour of an increase in serum TNF-alpha in DHA- (mean value 30.5 vs 21 in DHA- and DHAn, respectively). In addition, the DHA- group have had significantly (p=0.03) more hospitalisations since the beginning of the disorder. The duration of untreated psychosis was 4 years vs 1 year in the DHA- vs DHAn groups, respectively. The same applied for the mean duration of hospitalisations (45 vs 34 days in DHA- vs DHAn). These values could not be explained by a longer duration in disease treatment in the 2 subpopulations.DiscussionThe presented data are in accordance with repeated findings showing decreased RBC membrane DHA and total PUFA content in a subgroup of individuals meeting criteria for schizophrenia. The splitting of the studied population into 2 groups numerically comparable as a function of their RBC membrane DHA content was thus justified. Interestingly, patients with lower membrane DHA content also exhibited abnormalities in other known biomarkers described in schizophrenia such as increased inflammation and disease severity. The presented data also show for the first time a biomarker associated with the duration of untreated psychosis. Altogether, these results, despite preliminary, are paving the way towards the identification of schizophrenia subtypes.

SAT-137 The Effect of Hypertriglyceridemia on Triple Negative Breast Cancer Progression

Obesity is associated with increased cancer risk and cancer-associated mortality1,2. Hypertriglyceridemia (HTG), a component of the metabolic syndrome which frequently co-exists with obesity, has been associated with increased breast cancer risk and mortality in triple negative breast cancer (TNBC)3,4. To determine if HTG is causally related to enhanced TNBC progression in the absence of other obesity-associated characteristics, TNBC growth and metastasis in a mouse model of HTG was examined. Mice overexpressing human apolipoprotein C3 (AC3) were backcrossed onto FVB/N background and crossed with recombination-activating gene 1 (Rag1) knockout mice to generate immunodeficient HTG mice. AC3 mice relative to wild-type (WT) littermates showed a 20-fold higher circulating triglycerides (p < 0.0001) and elevated very low density lipoprotein (VLDL) cholesterol (p = 0.001). No differences in body weight, body composition, blood glucose or plasma insulin levels were observed between the two groups, allowing for investigation on the influence of HTG on TNBC without confounders such as hyperinsulinemia or hyperglycemia. AC3 mice orthotopically implanted with the mouse mammary tumor cell line, Mvt1, showed both increased tumor growth (AC3 vs WT: 1157.0 ± 84.2 vs 707.2 ± 58.6 mm3, p = 0.0009) and lung metastasis (AC3 vs WT: 57.3 ± 3.0 vs 32.9 ± 5.3 mm3, p = 0.001) relative to WT mice. Immunodeficient Rag1/AC3 mice likewise, showed increased tumor growth compared to WT controls when implanted with human TNBC MDA-MB-231 cells (AC3 vs WT: 363.2 ± 113.9 vs 92.95 ± 16.2 mm3, p = 0.038). To investigate how HTG affects tumor lipid metabolism, serum and tumors from both groups were analyzed by liquid chromatography/mass spectrometry. Total alkyl-acyl, di-acyl-phosphatidylcholines and sphingomyelin concentrations were higher in the serum of AC3 mice relative to WT. In contrast, no overall difference in tumor phospholipid or acylcarnitine content was noted between AC3 and WT mice, suggesting no difference in fatty acid oxidation in the setting of HTG. Mvt1 tumors from AC3 and WT mice were analyzed by RNA sequencing. Decreased expression of genes associated with cholesterol synthesis (Fdft1, Pvmk, Acss2) were found in tumors from AC3 mice. Tumors from AC3 mice also showed decreased protein expression of LDLR, which is associated with LDL cholesterol uptake. Overall, these findings suggest that HTG, independently of other obesity-associated characteristics such as hyperinsulinemia and hyperglycemia, leads to changes in intracellular lipid metabolism and promotes TNBC progression.

SAT-LB127 Regulation of ENaC by Exosomal Lipids in the Diabetic Kidney

Effective treatment of hypertension (HTN) in patients with diabetes may help to significantly reduce the risk of those patients developing additional complications including vascular disease and diabetic nephropathy. Blockers of the renin-angiotensin system including angiotensin converting enzyme inhibitors and angiotensin receptor blockers are not always effective in treating HTN in diabetic patients. Therefore, the aim of this study was to use an animal model of type 2 diabetes to investigate a novel mechanism of diabetes associated HTN involving exosomal lipids in the upregulation of epithelial sodium channel (ENaC) activity in the kidney. We performed metabolic cages studies using male and female hypertensive (salt-loaded induced) diabetic db/db mice and healthy age-matched wild-type control mice in order to isolate and characterize urinary exosomes from each group by nanoparticle tracking analysis, Western blotting, and transmission electron microscopy. Our mass spectrometry based lipidomic studies identified key lipids that were differentially expressed in the kidney derived exosomes from the hypertensive diabetic mice compared to control mice. Sphingomyelin quantification assays showed total sphingomyelin content was elevated in the exosomes from the hypertensive diabetic mice compared to the control group. Single channel patch clamp studies showed urinary exosomes enriched in sphingomyelins from hypertensive diabetic mice compared to controls increase ENaC activity (at the level of channel density and open probability) in cultured distal tubule renal epithelial cells. Moreover, exogenous application of sphinomyelin-6 to cultured mouse cortical collecting duct (mpkCCD) cells resulted in an increase in amiloride-sensitive transepithelial current. Taken together, our data show various lipids are enriched in exosomes from hypertensive diabetic mice compared to controls and these exosomes positively regulate ENaC activity in distal tubule and collecting duct cells.

Abstract IA08: Lipid dependence of KRAS plasma membrane interactions

Abstract RAS proteins must localize to the plasma membrane (PM) in order to function. We have examined how different RAS PM anchors select and assemble highly specific phospholipids into signaling platforms called nanoclusters, how these transient lipid assemblies impact signal transmission, and in consequence how the lipid composition of the PM can operate as high-level regulator of RAS signal transmission. For example, the KRAS polybasic domain (PBD)-farnesyl membrane anchor exhibits exquisite specificity for phosphatidylserine (PtdSer) over other anionic phospholipids by virtue of defined structural dynamics of the C-terminal polybasic domain and farnesyl group. This specificity extends to PtdSer with specific combinations of lipid side chains. PtdSer binding is therefore essential for stable KRAS PM binding and the spatial organization of KRAS into nanoclusters. These and complementary results with RAC1 highlight the critical role of specific anionic PM lipids in the biologic function of small GTPases. In this context for KRAS we have now shown that the PM levels and lateral availability of PtdSer are critically dependent on sphingomyelin metabolism such that multiple perturbations of sphingomyelin content or distribution, or endolysosmal lipid trafficking, profoundly affect KRAS plasma membrane localization, nanoclustering, and function. Concordantly, directly targeting the molecular machinery that maintains PtdSer on the PM also abrogates KRAS function in multiple pancreatic cancer cell lines. These new observations suggest multiple new potential therapeutic targets to abrogate oncogenic KRAS signaling, which we are evaluating in model systems. Citation Format: John F. Hancock. Lipid dependence of KRAS plasma membrane interactions [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr IA08.

A Review of Lipidomics of Cardiovascular Disease Highlights the Importance of Isolating Lipoproteins.

Cutting-edge lipidomic profiling measures hundreds or even thousands of lipids in plasma and is increasingly used to investigate mechanisms of cardiovascular disease (CVD). In this review, we introduce lipidomic techniques, describe distributions of lipids across lipoproteins, and summarize findings on the association of lipids with CVD based on lipidomics. The main findings of 16 cohort studies were that, independent of total and high-density lipoprotein cholesterol (HDL-c), ceramides (d18:1/16:0, d18:1/18:0, and d18:1/24:1) and phosphatidylcholines (PCs) containing saturated and monounsaturated fatty acyl chains are positively associated with risks of CVD outcomes, while PCs containing polyunsaturated fatty acyl chains (PUFA) are inversely associated with risks of CVD outcomes. Lysophosphatidylcholines (LPCs) may be positively associated with risks of CVD outcomes. Interestingly, the distributions of the identified lipids vary across lipoproteins: LPCs are primarily contained in HDLs, ceramides are mainly contained in low-density lipoproteins (LDLs), and PCs are distributed in both HDLs and LDLs. Thus, the potential mechanism behind previous findings may be related to the effect of the identified lipids on the biological functions of HDLs and LDLs. Only eight studies on the lipidomics of HDL and non-HDL particles and CVD outcomes have been conducted, which showed that higher triglycerides (TAGs), lower PUFA, lower phospholipids, and lower sphingomyelin content in HDLs might be associated with a higher risk of coronary heart disease (CHD). However, the generalizability of these studies is a major concern, given that they used case–control or cross-sectional designs in hospital settings, included a very small number of participants, and did not correct for multiple testing or adjust for blood lipids such as HDL-c, low-density lipoprotein cholesterol (LDL-c), or TAGs. Overall, findings from the literature highlight the importance of research on lipidomics of lipoproteins to enhance our understanding of the mechanism of the association between the identified lipids and the risk of CVD and allow the identification of novel lipid biomarkers in HDLs and LDLs, independent of HDL-c and LDL-c. Lipidomic techniques show the feasibility of this exciting research direction, and the lack of high-quality epidemiological studies warrants well-designed prospective cohort studies.

Воздействие наноразмерных анионов кремний-молибденовой кислоты на плазматическую мембрану фибробластов эмбриона человека

Методом времяпролетной масс-спектрометрии вторичных ионов (ToF-SIMS) исследованы изменения состава плазматических мембран (ПМ) фибробластов эмбриона человека под воздействием наноразмерных анионов кремний-молибденовой кислоты (КМК). Измерены и интерпретированы зависимости масс-спектров основных липидов ПМ от концентрации КМК, коррелирующие с их послойными распределениями и со сродством холестерина к фосфолипидам. Обнаружен новый для биохимии клетки эффект – значительное снижение относительного содержания в ПМ холестерина и сфингомиелина под воздействием многозарядных анионов гетерополикислоты (ГПК). Для водных растворов КМК при концентрации С ~ 10мкМ/л и периода воздействия 48 ч обнаружено, что количество холестерина в ПМ снижается в 2–2.5 раза, при этом количество сфингомиелина уменьшается на 20–25%. Предложен новый механизм начального воздействия ГПК на плазматические мембраны, сводящийся к селективному травлению многозарядными анионами. Согласно предлагаемому механизму на первом этапе взаимодействия аниона полиоксометаллата с клеткой осуществляется экстракция из ПМ холестерина и сфингомиелина – основных регуляторов проницаемости и микровязкости ПМ. Как следствие возросшей проницаемости ПМ в клетках возможно ускорение жизненно важных трансмембранных и латеральных процессов.

Lipid composition and organization helps plasma membrane repair and offers novel therapeutic target to treat degenerative muscle disease

The plasma membrane of all cells is routinely injured, with considerable investigative effort focused on understanding how proteins help repair this injury. Despite being the most abundant component of the plasma membrane, the role of lipids in repairing injured mammalian cells has remained unexplored. Through systematic live cell imaging we have examined the involvement of lipids in plasma membrane repair following injury. This shows that change in composition and localization of plasma membrane lipids is crucial for repair. Specifically, we find that cell injury results in a rapid change in local cholesterol and sphingomyelin content, and failure of which increases membrane fluidity and compromises membrane repair. Plasma membrane injury also alters the local composition of phospholipids including PIP2 and diacylglycerol (DAG), which is required for the repair of the injured plasma membrane. Failure of these lipid changes in muscle fibers injured by mechanical or other activity, results in myofiber death and Limb Girdle Muscular Dystrophy (LGMD2B). To target this deficit we developed a gene therapy approach to exogenously modify the plasma membrane lipid composition in a mouse model of LGMD2B. This approach improved the repair of the dystrophic muscle, attenuated myofiber death and improved muscle strength and histopathology. These findings provide direct evidence of the diverse roles of lipids in not only maintaining the integrity of the plasma membrane, but also in re‐establishing its integrity following injury. Here, we establish the clinical relevance of the structural and signaling roles of lipids in cell repair, and identify therapeutic approaches that address these deficits in muscle diseases.Support or Funding InformationThis work is supported by R01AR055686 from NIH/NIAMS.

Low Plasma Sphingomyelin Levels Show a Weak Association with Poor Neurological Outcome in Cardiac Arrest Patients: Results from the Prospective, Observational COMMUNICATE Trial.

There is interest in novel blood markers to improve risk stratification in patients presenting with cardiac arrest. We assessed associations of different plasma sphingomyelin concentrations and neurological outcome in patients with cardiac arrest. In this prospective observational study, adult patients with cardiac arrest were included upon admission to the intensive care unit (ICU). We studied associations of admission plasma levels of 15 different sphingomyelin species with neurological outcome at hospital discharge (primary endpoint) defined by the modified Rankin Scale by the calculation of univariable and multivariable logistic regression models adjusted for age, gender, and clinical shock markers. We included 290 patients (72% males, median age 65 years) with 162 (56%) having poor neurological outcome at hospital discharge. The three sphingomyelin species SM C24:0, SM(OH) C22:1, and SM(OH) C24:1 were significantly lower in patients with poor neurological outcome compared to patients with favorable outcome with areas under the curve (AUC) of 0.58, 0.59, and 0.59. SM(OH) C24:1 was independently associated with poor neurological outcome in a fully-adjusted regression model (adjusted odds ratio per log-transformed unit increase in SM(OH) C24:1 blood level 0.18, 95% CI 0.04 to 0.87, p = 0.033). Results were similar for 1-year mortality. Low admission sphingomyelin levels showed a weak association with poor neurological outcome in patients after cardiac arrest. If validated in future studies, a better understanding of biological sphingomyelin function during cardiac arrest may help to further advance the therapeutic approach and risk stratification in this vulnerable patient group.

Myeloperoxidase and Septic Conditions Disrupt Sphingolipid Homeostasis in Murine Brain Capillaries In Vivo and Immortalized Human Brain Endothelial Cells In Vitro.

During inflammation, activated leukocytes release cytotoxic mediators that compromise blood–brain barrier (BBB) function. Under inflammatory conditions, myeloperoxidase (MPO) is critically involved in inflicting BBB damage. We used genetic and pharmacological approaches to investigate whether MPO induces aberrant lipid homeostasis at the BBB in a murine endotoxemia model. To corroborate findings in a human system we studied the impact of sera from sepsis and non-sepsis patients on brain endothelial cells (hCMEC/D3). In response to endotoxin, the fatty acid, ceramide, and sphingomyelin content of isolated mouse brain capillaries dropped and barrier dysfunction occurred. In mice, genetic deficiency or pharmacological inhibition of MPO abolished these alterations. Studies in metabolic cages revealed increased physical activity and less pronounced sickness behavior of MPO−/− compared to wild-type mice in response to sepsis. In hCMEC/D3 cells, exogenous tumor necrosis factor α (TNFα) potently regulated gene expression of pro-inflammatory cytokines and a set of genes involved in sphingolipid (SL) homeostasis. Notably, treatment of hCMEC/D3 cells with sera from septic patients reduced cellular ceramide concentrations and induced barrier and mitochondrial dysfunction. In summary, our in vivo and in vitro data revealed that inflammatory mediators including MPO, TNFα induce dysfunctional SL homeostasis in brain endothelial cells. Genetic and pharmacological inhibition of MPO attenuated endotoxin-induced alterations in SL homeostasis in vivo, highlighting the potential role of MPO as drug target to treat inflammation-induced brain dysfunction.

Sex-specific perturbation of complex lipids in response to medium-chain fatty acids in very long-chain acyl-CoA dehydrogenase deficiency.

Very-long-chain acyl-CoA dehydrogenase deficiency (VLCAD) is the most common defect of long-chain fatty acid β-oxidation. The recommended treatment includes the application of medium-chain triacylglycerols (MCTs). However, long-term treatment of VLCAD-/- mice resulted in the development of a sex-specific metabolic syndrome due to the selective activation of the ERK/mTORc1 signalling in females and ERK/peroxisome proliferator-activated receptor gamma pathway in males. In order to investigate a subsequent sex-specific effect of MCT on the lipid composition of the cellular membranes, we performed lipidomic analysis, SILAC-based quantitative proteomics and gene expression in fibroblasts from WT and VLCAD-/- mice of both sexes. Treatment with octanoate (C8) affected the composition of complex lipids resulting in a sex-specific signature of the molecular profile. The content of ceramides and sphingomyelins in particular differed significantly under control conditions and increased markedly in cells from mutant female mice but remained unchanged in cells from mutant males. Moreover, we observed a specific upregulation of biosynthesis of plasmalogens only in male mice, whereas in females C8 led to the accumulation of higher concentration of phosphatidylcholines and lysophosphatidylcholines. Our data on membrane lipids in VLCAD after supplementation with C8 provide evidence of a sex-specific lipid perturbation. We hypothesize a likely C8-induced pro-inflammatory response contributing to the development of a severe metabolic syndrome in female VLCAD-/- mice on long-term MCT supplementation.

Sphingolipid Signature of Human Feto-Placental Vasculature in Preeclampsia.

Bioactive sphingolipids are emerging as key regulators of vascular function and homeostasis. While most of the clinical studies have been devoted to profile circulating sphingolipids in maternal plasma, little is known about the role of the sphingolipid at the feto-placental vasculature, which is in direct contact with the offspring circulation. Our study aims to compare the sphingolipid profile of normal with preeclamptic (PE) placental chorionic arteries and isolated endothelial cells, with the goal of unveiling potential underlying pathomechanisms in the vasculature. Dihydrosphingosine and sphingomyelin (SM) concentrations (C16:0-, C18:0-, and C24:0- sphingomyelin) were significantly increased in chorionic arteries of preeclamptic placentas, whereas total ceramide, although showing a downward trend, were not statistically different. Moreover, RNA and immunofluorescence analysis showed impaired sphingosine-1-phosphate (S1P) synthesis and signaling in PE vessels. Our data reveal that the exposure to a deranged maternal intrauterine environment during PE alters the sphingolipid signature and gene expression on the fetal side of the placental vasculature. This pathological remodeling consists in increased serine palmitoyltransferase (SPT) activity and SM accrual in PE chorionic arteries, with concomitance impairment endothelial S1P signaling in the endothelium of these vessels. The increase of endothelial S1P phosphatase, lyase and S1PR2, and blunted S1PR1 expression support the onset of the pathological phenotype in chorionic arteries.

Enzyme-modified microelectrodes for electrochemical detection of sphingomyelin in the plasma membranes of single cells

In this communication, sphingomyelin (SM) in the plasma membrane of single cells is detected electrochemically using an enzyme-modified Pt microelectrode for the first time. The enzymes immobilized at the electrode surface, which include sphingomyelinase (SMase), alkaline phosphatase (ALP), and choline oxidase, react with SM in a series of reactions to generate hydrogen peroxide. The electrochemical oxidation of hydrogen peroxide induces an elevation in the current, which offers a quantitative determination of SM in a range from 140 to 560 µM. Further contact of the microelectrode with one oocyte cell results in the reaction of SM in the plasma membrane with the enzymes at the electrode. The resulting current increase is correlated with the content of SM in the plasma membrane, confirming the electrochemical detection of membrane SM in single cells. This success in single cell electrochemical analysis of membrane SM expands the application of microelectrodes in single cell studies, which will help in the elucidation of cellular heterogeneity in lipid trafficking.

Association of α/β-Hydrolase D16B with Bovine Conception Rate and Sperm Plasma Membrane Lipid Composition.

We have identified a Holstein sire named Tarantino who had been approved for artificial insemination that is based on normal semen characteristics (i.e., morphology, thermoresistance, motility, sperm concentration), but had no progeny after 412 first inseminations, resulting in a non-return rate (NRdev) of −29. Using whole genome association analysis and next generation sequencing, an associated nonsense variant in the α/β-hydrolase domain-containing 16B gene (ABHD16B) on bovine chromosome 13 was identified. The frequency of the mutant allele in the German Holstein population was determined to be 0.0018 in 222,645 investigated cattle specimens. The mutant allele was traced back to Whirlhill Kingpin (bornFeb. 13th, 1959) as potential founder. The expression of ABHD16B was detected by Western blotting and immunohistochemistry in testis and epididymis of control bulls. A lipidome comparison of the plasma membrane of fresh semen from carriers and controls showed significant differences in the concentration of phosphatidylcholine (PC), diacylglycerol (DAG), ceramide (Cer), sphingomyelin (SM), and phosphatidylcholine (-ether) (PC O-), indicating that ABHD16B plays a role in lipid biosynthesis. The altered lipid contents may explain the reduced fertilization ability of mutated sperms.

Fatty acid profile of phospholipids and sphingomyelin in milk and regulation of sphingomyelin synthesis of mammary glands in cows receiving increasing levels of crushed sunflower seeds

The objective of this study was to investigate the effect of increasing dietary supplementation of crushed sunflower seed (CSS) in the diet of dairy cows on the fatty acid (FA) composition of phospholipids and sphingomyelin in milk, and on mammary transcription of genes that are important for sphingomyelin de novo synthesis. Four groups of 6 cows received diets supplemented with CSS at 0% (control), or 5, 10, or 15% of dry matter for a 5-wk experimental period. Milk samples and mammary biopsies were collected at the end of the experiment. Phospholipid concentration in milk fat decreased linearly with CSS supplementation. Sphingomyelin concentration in milk fat was unaffected by CSS supplementation. Daily yield of phospholipids decreased linearly with CSS supplementation. Daily yield of sphingomyelin was not significantly affected. The CSS supplementation linearly increased the proportion of monounsaturated FA in milk phospholipids. The major isomer incorporated into phospholipids was C18:1 (n-9 cis), which showed a linear increase with CSS supplementation. The C22:0 proportion in sphingomyelin increased linearly with CSS supplementation and constituted between 15.2 to 25.4% of total FA in sphingomyelin. However, CSS supplementation linearly decreased C23:0 sphingomyelin. Mammary transcription of serine palmitoyl transferase, long chain subunit 1 and subunit 2, the rate-limiting enzymes in ceramide synthesis, showed a linear decrease with increasing CSS supplementation. In conclusion, the data showed that dietary supplementation of CSS linearly increased the proportion of unsaturated FA and monounsaturated FA in milk phospholipids with no effect on phospholipid concentration. In addition, CSS supplementation linearly decreased n-3 polyunsaturated fatty acid proportion in sphingomyelin. The results further showed that mammary transcription of important genes for sphingomyelin de novo synthesis is regulated by lipid supplementation.

Urinary metabolomics fingerprinting around parturition identifies metabolites that differentiate lame dairy cows from healthy ones

Lameness is a very important disorder of periparturient dairy cows with implications on milk production and composition as well as with consequences on reproductive performance. The aetiology of lameness is not clear although there have been various hypotheses suggested over the years. The objective of this study was to metabotype the urine of dairy cows prior to, during and after the onset of lameness by evaluating at weeks −8, −4 pre-calving, the week of lameness diagnosis, and +4 and +8 weeks post-calving. We used a metabolomics approach to analyse urine samples collected from dairy cows around calving (6 cows with lameness v. 20 healthy control cows). A total of 153 metabolites were identified and quantified using an in-house MS library and classified into 6 groups including: 11 amino acids (AAs), 39 acylcarnitines (ACs), 3 biogenic amines (BAs), 84 glycerophospholipids, 15 sphingolipids and hexose. A total of 23, 36, 40, 23 and 49 metabolites were observed to be significantly different between the lame and healthy cows at −8 and −4 weeks pre-calving, week of lameness diagnosis as well as at +4 and +8 weeks post-calving, respectively. It should be noted that most of the identified metabolites were elevated; however, a few of them were also lower in lame cows. Overall, ACs and glycerophospholipids, specifically phosphatidylcholines (PCs), were the metabolite groups displaying the strongest differences in the urine of pre-lame and lame cows. Lysophosphatidylcholines (LysoPCs), although to a lesser extent than PCs, were altered at all time points. Alterations in urinary AA concentrations were also observed during the current study for four time points. During the pre-calving period, there was an observed elevation of arginine (−8 week), tyrosine (−8 week) and aspartate (−4 week), as well as a depression of urinary glutamate (−4 weeks). In the current study, it was additionally observed that concentrations of several sphingomyelins and one BA were altered in pre-lame and lame cows. Symmetric dimethylarginine was elevated at both −8 weeks pre-calving and the week of lameness diagnosis. Data showed that urinary fingerprinting might be a reliable methodology to be used in the future to differentiate lame cows from healthy ones.

Exploration of Plasma Lipids in Mild Cognitive Impairment due to Alzheimer's Disease.

Lipids have important structural roles in cell membranes and changes to these membrane lipids may influence β- and γ-secretase activities and thus contribute to Alzheimer's disease (AD) pathology. To explore baseline plasma lipid profiling in participants with mild cognitive impairment (MCI) with and without AD pathology. We identified 261 plasma lipids using reversed-phase liquid chromatography/mass spectrometry in cerebrospinal fluid amyloid positive (Aβ+) or negative (Aβ-) participants with MCI as compared to controls. Additionally, we analyzed the potential associations of plasma lipid profiles with performance on neuropsychological tests at baseline and after two years. Sphingomyelin (SM) concentrations, particularly, SM(d43:2), were lower in MCI Aβ+ individuals compared to controls. Further, SM(d43:2) was also nominally reduced in MCI Aβ+ individuals compared to MCI Aβ-. No plasma lipids were associated with performance on primary neuropsychological tests at baseline or between the two time points after correction for multiple testing. Reduced plasma concentrations of SM were associated with AD.