Publications by authors named "Alaa Othman"

39 Publications

Postendodontic pain in asymptomatic necrotic teeth prepared with different rotary instrumentation techniques.

J Family Med Prim Care 2020 Jul 30;9(7):3474-3479. Epub 2020 Jul 30.

Department of Restorative Dental Sciences, Alfarabi Colleges of Dentistry and Nursing, Riyadh, Saudi Arabia.

Objectives: to investigate the postendodontic pain in asymptomatic necrotic teeth prepared with different rotary instrumentation techniques after single-visit root canal treatment.

Materials And Methods: A total of 60 single-rooted teeth with single root canal were treated endodontically. Teeth were divided randomly into four equaled groups ( = 15) according to instrumentation systems as follows: group I were shaped using ProTaper Universal (control group) (Dentsply/Maillefer, Ballaigues), group 2 were shaped with 2Shape (Micro-Mega) till TS2 (25.06), group 3 were shaped with XP-endo Shaper file (FKG Dentaire) till #30.04, and group 4 were shaped with Reciproc blue (VDW) till R25 (25.08). All groups were prepared according to manufacturer's instructions and obturated with lateral condensation technique. Pain levels were assessed by visual analog scale (VAS) and verbal evaluation of pain questionnaire after 6, 12, 24, 48 h, and 7 days of canal obturation. Data were then analyzed using Kruskal-Wallis and Mann-Whitney U tests at value of 0.05.

Results: Postendodontic pain started after 6 h of treatment with highest values and then decreased gradually until almost vanished after 1 week of treatment, with no significant differences in VAS among studied groups (ProTaper, 2 shape, XP endo Shaper, and Reciproc Blue) after 6,12, and 48 h of treatment. On the other hand, XP endo Shaper group, showed the lowest pain values after 24 h of treatment, and the highest pain values were found in 2 shape group after 1 week with significance ( < 0.05).

Conclusion: Root canals prepared with XP endo Shaper resulted in the lowest pain levels after 24 h of treatment. Root canal preparation with 2Sshape rotary system resulted in the highest pain levels after 1 week of treatment.
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http://dx.doi.org/10.4103/jfmpc.jfmpc_342_20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7567189PMC
July 2020

Cell-Derived Vesicles as TRPC1 Channel Delivery Systems for the Recovery of Cellular Respiratory and Proliferative Capacities.

Adv Biosyst 2020 11 2;4(11):e2000146. Epub 2020 Sep 2.

Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, MD6, 14 Medical Drive, Singapore, 117599, Singapore.

Pulsed electromagnetic fields (PEMFs) are capable of specifically activating a TRPC1-mitochondrial axis underlying cell expansion and mitohormetic survival adaptations. This study characterizes cell-derived vesicles (CDVs) generated from C2C12 murine myoblasts and shows that they are equipped with the sufficient molecular machinery to confer mitochondrial respiratory capacity and associated proliferative responses upon their fusion with recipient cells. CDVs derived from wild type C2C12 myoblasts include the cation-permeable transient receptor potential (TRP) channels, TRPC1 and TRPA1, and directly respond to PEMF exposure with TRPC1-mediated calcium entry. By contrast, CDVs derived from C2C12 muscle cells in which TRPC1 has been genetically knocked-down using CRISPR/Cas9 genome editing, do not. Wild type C2C12-derived CDVs are also capable of restoring PEMF-induced proliferative and mitochondrial activation in two C2C12-derived TRPC1 knockdown clonal cell lines in accordance to their endogenous degree of TRPC1 suppression. C2C12 wild type CDVs respond to menthol with calcium entry and accumulation, likewise verifying TRPA1 functional gating and further corroborating compartmental integrity. Proteomic and lipidomic analyses confirm the surface membrane origin of the CDVs providing an initial indication of the minimal cellular machinery required to recover mitochondrial function. CDVs hence possess the potential of restoring respiratory and proliferative capacities to senescent cells and tissues.
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http://dx.doi.org/10.1002/adbi.202000146DOI Listing
November 2020

Defects in High Density Lipoprotein metabolism and hepatic steatosis in mice with liver-specific ablation of Hepatocyte Nuclear Factor 4A.

Metabolism 2020 09 3;110:154307. Epub 2020 Jul 3.

Laboratory of Biochemistry, University of Crete Medical School, Heraklion 71003, Greece; Gene Regulation and Genomics group, Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology of Hellas, Heraklion 70013, Greece. Electronic address:

Background: Aberrant concentration, structure and functionality of High Density Lipoprotein (HDL) are associated with many prevalent diseases, including cardiovascular disease and non-alcoholic fatty liver disease (NAFLD). Mice with liver-specific ablation of Hnf4α (H4LivKO) present steatosis and dyslipidemia by mechanisms that are not completely understood. The aim of this study was to explore the role of liver HNF4A in HDL metabolism and the development of steatosis.

Methods And Results: Serum and tissue samples were obtained from 6-weeks old H4LivKO mice and their littermate controls. Liver and serum lipids were measured and HDL structure and functionality were assessed. Global gene expression changes in the liver were analyzed by expression arrays, validations were performed by RT-qPCR and DNA-protein interactions were studied by chromatin immunoprecipitation (ChIP). H4LivKO mice presented liver steatosis, increased liver triglyceride content and decreased concentration of serum total cholesterol, HDL cholesterol, triglycerides, phospholipids and cholesteryl esters. Most classes of phospholipids showed significant changes in species ratio and sphingosine-1-phosphate (S1P) levels were reduced. H4LivKO serum was enriched in the smaller, denser HDL particles, devoid of APOA2 and APOM apolipoproteins, exhibiting decreased activity of paraoxonase-1 but retaining macrophage cholesterol efflux capacity and phospho-AKT activation in endothelial cells. Global gene expression analysis revealed the association of liver HNF4A with known and novel regulators of HDL metabolism as well as NAFLD-susceptibility genes.

Conclusions: HNF4A ablation in mouse liver causes hepatic steatosis, perturbations in HDL structure and function and significant global changes in gene expression. This study reveals new targets of HNF4A involved in HDL metabolism and the development of steatosis and enriches our knowledge on HDL functionality in NAFLD.
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http://dx.doi.org/10.1016/j.metabol.2020.154307DOI Listing
September 2020

Astrocyte glutathione maintains endothelial barrier stability.

Redox Biol 2020 07 19;34:101576. Epub 2020 May 19.

Institute for Veterinary Physiology, University of Zurich, Winterthurerstrasse 260, CH-8057, Zurich, Switzerland; Zurich Center for Integrative Human Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland. Electronic address:

Blood-brain barrier (BBB) impairment clearly accelerates brain disease progression. As ways to prevent injury-induced barrier dysfunction remain elusive, better understanding of how BBB cells interact and modulate barrier integrity is needed. Our metabolomic profiling study showed that cell-specific adaptation to injury correlates well with metabolic reprogramming at the BBB. In particular we noted that primary astrocytes (AC) contain comparatively high levels of glutathione (GSH)-related metabolites compared to primary endothelial cells (EC). Injury significantly disturbed redox balance in EC but not AC motivating us to assess 1) whether an AC-EC GSH shuttle supports barrier stability and 2) the impact of GSH on EC function. Using an isotopic labeling/tracking approach combined with Time-of-Flight Mass Spectrometry (TOF-MS) we prove that AC constantly shuttle GSH to EC even under resting conditions - a flux accelerated by injury conditions in vitro. In correlation, co-culture studies revealed that blocking AC GSH generation and secretion via siRNA-mediated γ-glutamyl cysteine ligase (GCL) knockdown significantly compromises EC barrier integrity. Using different GSH donors, we further show that exogenous GSH supplementation improves barrier function by maintaining organization of tight junction proteins and preventing injury-induced tight junction phosphorylation. Thus the AC GSH shuttle is key for maintaining EC redox homeostasis and BBB stability suggesting GSH supplementation could improve recovery after brain injury.
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http://dx.doi.org/10.1016/j.redox.2020.101576DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7267730PMC
July 2020

MS and LC libraries for untargeted metabolomics: Enhancing method development and identification confidence.

J Chromatogr B Analyt Technol Biomed Life Sci 2020 May 4;1145:122105. Epub 2020 Apr 4.

Bioanalytic Core Facility, Center for Brain Behavior and Metabolism, University of Lübeck, Lübeck, Germany. Electronic address:

As part of the "omics" technologies in the life sciences, metabolomics is becoming increasingly important. In untargeted metabolomics, unambiguous metabolite identification and the inevitable coverage bias that comes with the selection of analytical conditions present major challenges. Reliable compound annotation is essential for translating metabolomics data into meaningful biological information. Here, we developed a fast and transferable method for generating in-house MS libraries to improve metabolite identification. Using the new method we established an in-house MS library that includes over 4,000 fragmentation spectra of 506 standard compounds for 6 different normalized collision energies (NCEs). Additionally, we generated a comprehensive liquid chromatography (LC) library by testing 57 different LC-MS conditions for 294 compounds. We used the library information to develop an untargeted metabolomics screen with maximum coverage of the metabolome that was successfully tested in a study of 360 human serum samples. The current work demonstrates a workflow for LC-MS/MS-based metabolomics, with enhanced metabolite identification confidence and the possibility to select suitable analysis conditions according to the specific research interest.
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http://dx.doi.org/10.1016/j.jchromb.2020.122105DOI Listing
May 2020

Screening and Treatment Program to Eliminate Hepatitis C in Egypt.

N Engl J Med 2020 03;382(12):1166-1174

From the Hepatology Department, National Liver Institute, Menoufia University, Shebeen El Kom (I.W., W.A.-R.), and the Endemic Medicine Department, Faculty of Medicine, Cairo University (G. Esmat, A.E., M.E.-S., A.C., W.E.A., W.D.), the Ministry of Health and Population (R.G., G. Elshishiney, A.S., S.A.M., M.A.S., K.A.H., S.A.G., N.E.N., A.E.S., S.E.S., H.E.T., E.E., H.G., A. Hashem, N.H., A.N.H., A.K., K.L., F.M., S. Mamoun, T.M., S. Mekky, A.M., A.O., O.R., E.R., A.R., T.S., R.S., M. Sharshar, H. Shawky, M. Shawky, W.S., H. Soror, M. Taha, M. Talha, A.T., M.Z., H.Z.), the National Committee for Control of Viral Hepatitis (K.K.), the Pediatrics Department (M.H.E.-S.), the Hepatology and Tropical Medicine Department (H.D.), and the Department of Medicine (Y.E.S., Y.O.), Ain Shams University, the Hepatology Department, National Hepatology and Tropical Medicine Research Institute (M.H.), the Communicable Diseases Control Cluster, World Health Organization (A. Hashish), the Medical Research Division, National Research Center (E.K., M.A.), and the Tropical Medicine Department, Al-Azhar University (I.A.), Cairo - all in Egypt.

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http://dx.doi.org/10.1056/NEJMsr1912628DOI Listing
March 2020

Structure-function relationships of HDL in diabetes and coronary heart disease.

JCI Insight 2020 01 16;5(1). Epub 2020 Jan 16.

Institute of Clinical Chemistry, University of Zurich and University Hospital of Zurich, Zurich, Switzerland.

High-density lipoproteins (HDL) contain hundreds of lipid species and proteins and exert many potentially vasoprotective and antidiabetogenic activities on cells. To resolve structure-function-disease relationships of HDL, we characterized HDL of 51 healthy subjects and 98 patients with diabetes (T2DM), coronary heart disease (CHD), or both for protein and lipid composition, as well as functionality in 5 cell types. The integration of 40 clinical characteristics, 34 nuclear magnetic resonance (NMR) features, 182 proteins, 227 lipid species, and 12 functional read-outs by high-dimensional statistical modeling revealed, first, that CHD and T2DM are associated with different changes of HDL in size distribution, protein and lipid composition, and function. Second, different cellular functions of HDL are weakly correlated with each other and determined by different structural components. Cholesterol efflux capacity (CEC) was no proxy of other functions. Third, 3 potentially novel determinants of HDL function were identified and validated by the use of artificially reconstituted HDL, namely the sphingadienine-based sphingomyelin SM 42:3 and glycosylphosphatidylinositol-phospholipase D1 for the ability of HDL to inhibit starvation-induced apoptosis of human aortic endothelial cells and apolipoprotein F for the ability of HDL to promote maximal respiration of brown adipocytes.
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http://dx.doi.org/10.1172/jci.insight.131491DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7030825PMC
January 2020

Telmisartan prevents development of obesity and normalizes hypothalamic lipid droplets.

J Endocrinol 2020 01;244(1):95-110

Institute of Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany.

The AT1 receptor blocker telmisartan (TEL) prevents diet-induced obesity. Hypothalamic lipid metabolism is functionally important for energy homeostasis, as a surplus of lipids induces an inflammatory response in the hypothalamus, thus promoting the development of central leptin resistance. However, it is unclear as to whether TEL treatment affects the lipid status in the hypothalamus. C57BL/6N mice were fed with chow (CONchow) or high-fat diet (CONHFD). HFD-fed mice were gavaged with TEL (8 mg/kg/day, 12 weeks, TELHFD). Mice were phenotyped regarding weight gain, energy homeostasis, and glucose control. Hypothalamic lipid droplets were analyzed by fluorescence microscopy. Lipidomics were assessed by performing liquid chromatography-mass spectrometry in plasma and hypothalami. Adipokines were investigated using immunosorbent assays. Glial fibrillary acidic protein (GFAP) was determined by Western blotting and immunohistochemical imaging. We found that body weight, energy homeostasis, and glucose control of TEL-treated mice remained normal while CONHFD became obese. Hypothalamic ceramide and triglyceride levels as well as alkyne oleate distribution were normalized in TELHFD. The lipid droplet signal in the tanycyte layer was higher in CONHFD than in CONchow and returned to normal under TELHFD conditions. High hypothalamic levels of GFAP protein indicate astrogliosis of CONHFD mice while normalized GFAP, TNFα, and IL1α levels of TELHFD mice suggest that TEL prevents hypothalamic inflammation. In conclusion, TEL has anti-obese efficacy and prevented lipid accumulation and lipotoxicity, which is accompanied by an anti-inflammatory effect in the murine hypothalamus. Our findings support the notion that a brain-related mechanism is involved in TEL-induced weight loss.
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http://dx.doi.org/10.1530/JOE-19-0319DOI Listing
January 2020

Macrophage NCOR1 protects from atherosclerosis by repressing a pro-atherogenic PPARγ signature.

Eur Heart J 2020 03;41(9):995-1005

Center for Molecular Cardiology, University of Zurich, Wagistrasse 12, 8952 Schlieren, Switzerland.

Aims: Nuclear receptors and their cofactors regulate key pathophysiological processes in atherosclerosis development. The transcriptional activity of these nuclear receptors is controlled by the nuclear receptor corepressors (NCOR), scaffolding proteins that form the basis of large corepressor complexes. Studies with primary macrophages demonstrated that the deletion of Ncor1 increases the expression of atherosclerotic molecules. However, the role of nuclear receptor corepressors in atherogenesis is unknown.

Methods And Results: We generated myeloid cell-specific Ncor1 knockout mice and crossbred them with low-density lipoprotein receptor (Ldlr) knockouts to study the role of macrophage NCOR1 in atherosclerosis. We demonstrate that myeloid cell-specific deletion of nuclear receptor corepressor 1 (NCOR1) aggravates atherosclerosis development in mice. Macrophage Ncor1-deficiency leads to increased foam cell formation, enhanced expression of pro-inflammatory cytokines, and atherosclerotic lesions characterized by larger necrotic cores and thinner fibrous caps. The immunometabolic effects of NCOR1 are mediated via suppression of peroxisome proliferator-activated receptor gamma (PPARγ) target genes in mouse and human macrophages, which lead to an enhanced expression of the CD36 scavenger receptor and subsequent increase in oxidized low-density lipoprotein uptake in the absence of NCOR1. Interestingly, in human atherosclerotic plaques, the expression of NCOR1 is reduced whereas the PPARγ signature is increased, and this signature is more pronounced in ruptured compared with non-ruptured carotid plaques.

Conclusions: Our findings show that macrophage NCOR1 blocks the pro-atherogenic functions of PPARγ in atherosclerosis and suggest that stabilizing the NCOR1-PPARγ binding could be a promising strategy to block the pro-atherogenic functions of plaque macrophages and lesion progression in atherosclerotic patients.
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http://dx.doi.org/10.1093/eurheartj/ehz667DOI Listing
March 2020

Brain endothelial specific gene therapy improves experimental Sandhoff disease.

J Cereb Blood Flow Metab 2020 06 29;40(6):1338-1350. Epub 2019 Jul 29.

Institute for Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany.

In Tay-Sachs and Sandhoff disease, a deficiency of the lysosomal enzyme β-hexosaminidase causes GM2 and other gangliosides to accumulate in neurons and triggers neurodegeneration. Although the pathology centers on neurons, β-hexosaminidase is mainly expressed outside of neurons, suggesting that gene therapy of these diseases should target non-neuronal cells to reconstitute physiological conditions. Here, we tested in mice, a model of Sandhoff disease, to determine whether endothelial expression of the genes for human β-hexosaminidase subunit A and B (, ) is able to reduce disease symptoms and prolong survival of the affected mice. The brain endothelial selective vectors AAV-BR1-CAG- and AAV-BR1-CAG- transduced brain endothelial cells, which subsequently released β-hexosaminidase enzyme. intravenous administration of the gene vectors to adult and neonatal mice prolonged survival. They improved neurological function and reduced accumulation of the ganglioside GM2 and the glycolipid GA2 as well as astrocytic activation. Overall, the data demonstrate that endothelial cells are a suitable target for intravenous gene therapy of GM2 gangliosidoses and possibly other lysosomal storage disorders.
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http://dx.doi.org/10.1177/0271678X19865917DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7238384PMC
June 2020

A Novel Variant (Asn177Asp) in SPTLC2 Causing Hereditary Sensory Autonomic Neuropathy Type 1C.

Neuromolecular Med 2019 06 6;21(2):182-191. Epub 2019 Apr 6.

Institute for Clinical Chemistry, University Hospital Zurich, University of Zurich, Wagistrasse 14 Schlieren, 8952, Zurich, Switzerland.

Hereditary sensory and autonomic neuropathy type 1 (HSAN1) is a rare, autosomal dominantly inherited, slowly progressive and length-dependent axonal peripheral neuropathy. HSAN1 is associated with several mutations in serine-palmitoyltransferase (SPT), the first enzyme in the de novo sphingolipid biosynthetic pathway. HSAN1 mutations alter the substrate specificity of SPT, which leads to the formation of 1-deoxysphingolipids, an atypical and neurotoxic subclass of sphingolipids. This study describes the clinical and neurophysiological phenotype of a German family with a novel SPTCL2 mutation (c.529A > G; N177D) associated with HSAN1 and the biochemical characterization of this mutation.) The mutaion was identified in five family members that segregated with the diesease. Patients were characterized genetically and clinically for neurophysiological function. Their plasma sphingolipid profiles were analyzed by LC-MS. The biochemical properties of the mutation were characterized in a cell-based activity assay. Affected family members showed elevated 1-deoxysphingolipid plasma levels. HEK293 cells expressing the N177D SPTLC2 mutant showed increased de novo 1-deoxysphingolipid formation, but also displayed elevated canonical SPT activity and increased C20 sphingoid base production. This study identifies the SPTLC2 N177D variant as a novel disease-causing mutation with increased 1-deoxySL formation and its association with a typical HSAN1 phenotype.
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http://dx.doi.org/10.1007/s12017-019-08534-wDOI Listing
June 2019

Impaired ABCA1/ABCG1-mediated lipid efflux in the mouse retinal pigment epithelium (RPE) leads to retinal degeneration.

Elife 2019 03 13;8. Epub 2019 Mar 13.

Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zurich, Schlieren, Switzerland.

Age-related macular degeneration (AMD) is a progressive disease of the retinal pigment epithelium (RPE) and the retina leading to loss of central vision. Polymorphisms in genes involved in lipid metabolism, including the ATP-binding cassette transporter A1 (), have been associated with AMD risk. However, the significance of retinal lipid handling for AMD pathogenesis remains elusive. Here, we study the contribution of lipid efflux in the RPE by generating a mouse model lacking ABCA1 and its partner ABCG1 specifically in this layer. Mutant mice show lipid accumulation in the RPE, reduced RPE and retinal function, retinal inflammation and RPE/photoreceptor degeneration. Data from human cell lines indicate that the AMD risk-conferring allele decreases expression, identifying the potential molecular cause that underlies the genetic risk for AMD. Our results highlight the essential homeostatic role for lipid efflux in the RPE and suggest a pathogenic contribution of reduced ABCA1 function to AMD.
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http://dx.doi.org/10.7554/eLife.45100DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6435327PMC
March 2019

Obesity-induced activation of JunD promotes myocardial lipid accumulation and metabolic cardiomyopathy.

Eur Heart J 2019 03;40(12):997-1008

Center for Molecular Cardiology, University of Zürich, Wagistrasse 12, Schlieren, Switzerland.

Aims: Metabolic cardiomyopathy (MC)-characterized by intra-myocardial triglyceride (TG) accumulation and lipotoxic damage-is an emerging cause of heart failure in obese patients. Yet, its mechanisms remain poorly understood. The Activator Protein 1 (AP-1) member JunD was recently identified as a key modulator of hepatic lipid metabolism in obese mice. The present study investigates the role of JunD in obesity-induced MC.

Methods And Results: JunD transcriptional activity was increased in hearts from diet-induced obese (DIO) mice and was associated with myocardial TG accumulation and left ventricular (LV) dysfunction. Obese mice lacking JunD were protected against MC. In DIO hearts, JunD directly binds PPARγ promoter thus enabling transcription of genes involved in TG synthesis, uptake, hydrolysis, and storage (i.e. Fas, Cd36, Lpl, Plin5). Cardiac-specific overexpression of JunD in lean mice led to PPARγ activation, cardiac steatosis, and dysfunction, thereby mimicking the MC phenotype. In DIO hearts as well as in neonatal rat ventricular myocytes exposed to palmitic acid, Ago2 immunoprecipitation, and luciferase assays revealed JunD as a direct target of miR-494-3p. Indeed, miR-494-3p was down-regulated in hearts from obese mice, while its overexpression prevented lipotoxic damage by suppressing JunD/PPARγ signalling. JunD and miR-494-3p were also dysregulated in myocardial specimens from obese patients as compared with non-obese controls, and correlated with myocardial TG content, expression of PPARγ-dependent genes, and echocardiographic indices of LV dysfunction.

Conclusion: miR-494-3p/JunD is a novel molecular axis involved in obesity-related MC. These results pave the way for approaches to prevent or treat LV dysfunction in obese patients.
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http://dx.doi.org/10.1093/eurheartj/ehy903DOI Listing
March 2019

DEGS1-associated aberrant sphingolipid metabolism impairs nervous system function in humans.

J Clin Invest 2019 03 11;129(3):1229-1239. Epub 2019 Feb 11.

Institute of Human Genetics, Medical Faculty, RWTH Aachen University, Aachen, Germany.

Background: Sphingolipids are important components of cellular membranes and functionally associated with fundamental processes such as cell differentiation, neuronal signaling, and myelin sheath formation. Defects in the synthesis or degradation of sphingolipids leads to various neurological pathologies; however, the entire spectrum of sphingolipid metabolism disorders remains elusive.

Methods: A combined approach of genomics and lipidomics was applied to identify and characterize a human sphingolipid metabolism disorder.

Results: By whole-exome sequencing in a patient with a multisystem neurological disorder of both the central and peripheral nervous systems, we identified a homozygous p.Ala280Val variant in DEGS1, which catalyzes the last step in the ceramide synthesis pathway. The blood sphingolipid profile in the patient showed a significant increase in dihydro sphingolipid species that was further recapitulated in patient-derived fibroblasts, in CRISPR/Cas9-derived DEGS1-knockout cells, and by pharmacological inhibition of DEGS1. The enzymatic activity in patient fibroblasts was reduced by 80% compared with wild-type cells, which was in line with a reduced expression of mutant DEGS1 protein. Moreover, an atypical and potentially neurotoxic sphingosine isomer was identified in patient plasma and in cells expressing mutant DEGS1.

Conclusion: We report DEGS1 dysfunction as the cause of a sphingolipid disorder with hypomyelination and degeneration of both the central and peripheral nervous systems.

Trial Registration: Not applicable.

Funding: Seventh Framework Program of the European Commission, Swiss National Foundation, Rare Disease Initiative Zurich.
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http://dx.doi.org/10.1172/JCI124159DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6391115PMC
March 2019

Circulating microRNAs -192 and -194 are associated with the presence and incidence of diabetes mellitus.

Sci Rep 2018 09 24;8(1):14274. Epub 2018 Sep 24.

Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland.

We sought to identify circulating microRNAs as biomarkers of prevalent or incident diabetes. In a pilot study of 18 sex- and age-matched patients with metabolic syndrome, nine of whom developed diabetes during 6 years of follow-up, an array of 372 microRNAs discovered significantly elevated serum levels of microRNAs -122, -192, -194, and -215 in patients who developed diabetes mellitus type 2 (T2DM). In two cross-sectional validation studies, one encompassing sex- and age-matched groups of patients with T2DM, impaired fasting glucose (IFG) and euglycemic controls (n = 43 each) and the other 53 patients with type 1 diabetes and 54 age- and BMI-matched euglycemic controls, serum levels of miR-192, miR-194, and mi215 were significantly higher in diabetic subjects than in probands with euglycemia or IFG. In a longitudinal study of 213 initially diabetes-free patients of whom 35 developed diabetes during 6 years of follow-up, elevated serum levels of microRNAs 192 and 194 were associated with incident T2DM, independently of fasting glucose, HbA1c and other risk factors. Serum levels of miR-192 and miR-194 were also elevated in diabetic Akt2 knockout mice compared to wild type mice. In conclusion, circulating microRNAs -192 and -194 are potential biomarkers for risk of diabetes.
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http://dx.doi.org/10.1038/s41598-018-32274-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6155281PMC
September 2018

Low-level mitochondrial heteroplasmy modulates DNA replication, glucose metabolism and lifespan in mice.

Sci Rep 2018 04 12;8(1):5872. Epub 2018 Apr 12.

Lübeck Institute of Experimental Dermatology, University of Lübeck, Lübeck, Germany.

Mutations in mitochondrial DNA (mtDNA) lead to heteroplasmy, i.e., the intracellular coexistence of wild-type and mutant mtDNA strands, which impact a wide spectrum of diseases but also physiological processes, including endurance exercise performance in athletes. However, the phenotypic consequences of limited levels of naturally arising heteroplasmy have not been experimentally studied to date. We hence generated a conplastic mouse strain carrying the mitochondrial genome of an AKR/J mouse strain (B6-mt) in a C57BL/6 J nuclear genomic background, leading to >20% heteroplasmy in the origin of light-strand DNA replication (OriL). These conplastic mice demonstrate a shorter lifespan as well as dysregulation of multiple metabolic pathways, culminating in impaired glucose metabolism, compared to that of wild-type C57BL/6 J mice carrying lower levels of heteroplasmy. Our results indicate that physiologically relevant differences in mtDNA heteroplasmy levels at a single, functionally important site impair the metabolic health and lifespan in mice.
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http://dx.doi.org/10.1038/s41598-018-24290-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5897405PMC
April 2018

Localization of 1-deoxysphingolipids to mitochondria induces mitochondrial dysfunction.

J Lipid Res 2017 01 23;58(1):42-59. Epub 2016 Nov 23.

LIMES Life and Medical Sciences Institute, University of Bonn, Bonn, Germany

1-Deoxysphingolipids (deoxySLs) are atypical sphingolipids that are elevated in the plasma of patients with type 2 diabetes and hereditary sensory and autonomic neuropathy type 1 (HSAN1). Clinically, diabetic neuropathy and HSAN1 are very similar, suggesting the involvement of deoxySLs in the pathology of both diseases. However, very little is known about the biology of these lipids and the underlying pathomechanism. We synthesized an alkyne analog of 1-deoxysphinganine (doxSA), the metabolic precursor of all deoxySLs, to trace the metabolism and localization of deoxySLs. Our results indicate that the metabolism of these lipids is restricted to only some lipid species and that they are not converted to canonical sphingolipids or fatty acids. Furthermore, exogenously added alkyne-doxSA [(2S,3R)-2-aminooctadec-17-yn-3-ol] localized to mitochondria, causing mitochondrial fragmentation and dysfunction. The induced mitochondrial toxicity was also shown for natural doxSA, but not for sphinganine, and was rescued by inhibition of ceramide synthase activity. Our findings therefore indicate that mitochondrial enrichment of an N-acylated doxSA metabolite may contribute to the neurotoxicity seen in diabetic neuropathy and HSAN1. Hence, we provide a potential explanation for the characteristic vulnerability of peripheral nerves to elevated levels of deoxySLs.
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http://dx.doi.org/10.1194/jlr.M068676DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5234710PMC
January 2017

Cytotoxic 1-deoxysphingolipids are metabolized by a cytochrome P450-dependent pathway.

J Lipid Res 2017 01 21;58(1):60-71. Epub 2016 Nov 21.

Institute for Clinical Chemistry, University Hospital Zurich, Zurich 8091, Switzerland

The 1-deoxysphingolipids (1-deoxySLs) are atypical sphingolipids (SLs) that are formed when serine palmitoyltransferase condenses palmitoyl-CoA with alanine instead of serine during SL synthesis. The 1-deoxySLs are toxic to neurons and pancreatic β-cells. Pathologically elevated 1-deoxySLs cause the inherited neuropathy, hereditary sensory autonomic neuropathy type 1 (HSAN1), and are also found in T2D. Diabetic sensory polyneuropathy (DSN) and HSAN1 are clinically very similar, suggesting that 1-deoxySLs may be implicated in both pathologies. The 1-deoxySLs are considered to be dead-end metabolites, as they lack the C1-hydroxyl group, which is essential for the canonical degradation of SLs. Here, we report a previously unknown metabolic pathway, which is capable of degrading 1-deoxySLs. Using a variety of metabolic labeling approaches and high-resolution high-accuracy MS, we identified eight 1-deoxySL downstream metabolites, which appear to be formed by cytochrome P450 (CYP)4F enzymes. Comprehensive inhibition and induction of CYP4F enzymes blocked and stimulated, respectively, the formation of the downstream metabolites. Consequently, CYP4F enzymes might be novel therapeutic targets for the treatment of HSAN1 and DSN, as well as for the prevention of T2D.
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http://dx.doi.org/10.1194/jlr.M072421DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5234722PMC
January 2017

Hyperglycemia in Stroke Impairs Polarization of Monocytes/Macrophages to a Protective Noninflammatory Cell Type.

J Neurosci 2016 09;36(36):9313-25

Institute of Experimental and Clinical Pharmacology and Toxicology, German Research Centre for Cardiovascular Research, 23562 Lübeck, Germany

Unlabelled: Hyperglycemia is common in patients with acute stroke, even in those without preexisting diabetes, and denotes a bad outcome. However, the mechanisms underlying the detrimental effects of hyperglycemia are largely unclear. In a mouse model of ischemic stroke, we found that hyperglycemia increased the infarct volume and decreased the number of protective noninflammatory monocytes/macrophages in the ischemic brain. Ablation of peripheral monocytes blocked the detrimental effect of hyperglycemia, suggesting that monocytes are required. In hyperglycemic mice, α-dicarbonyl glucose metabolites, the precursors for advanced glycation end products, were significantly elevated in plasma and ischemic brain tissue. The receptor of advanced glycation end products, AGER (previously known as RAGE), interfered with polarization of macrophages to a noninflammatory phenotype. When Ager was deleted, hyperglycemia did not aggravate ischemic brain damage any longer. Independently of AGER, methylglyoxal reduced the release of endothelial CSF-1 (M-CSF), which stimulates polarization of macrophages to a noninflammatory phenotype in the microenvironment of the ischemic brain. In summary, our study identified α-dicarbonyls and AGER as mediators by which hyperglycemia lowers the number of protective noninflammatory macrophages and consequently increases ischemic brain damage. Modulating the metabolism of α-dicarbonyls or blocking AGER may improve the treatment of stroke patients with hyperglycemia.

Significance Statement: Although glucose is the main energy substrate of the brain, hyperglycemia aggravates ischemic brain damage in acute stroke. So far, clinical trials have indicated that insulin treatment provides no solution to this common clinical problem. This study shows, in an experimental stroke model, that hyperglycemia interferes with the polarization of monocytes/macrophages to a protective cell type. Key players are α-dicarbonyls and the receptor for advanced glycation end products (AGER). Deletion of AGER normalized monocyte/macrophage polarization and reversed the detrimental effects of hyperglycemia, suggesting new avenues to treat stroke patients.
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http://dx.doi.org/10.1523/JNEUROSCI.0473-16.2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6601875PMC
September 2016

Elucidating the chemical structure of native 1-deoxysphingosine.

J Lipid Res 2016 07 10;57(7):1194-203. Epub 2016 May 10.

Institute of Clinical Chemistry, University and University Hospital of Zurich, CH-8091 Zurich, Switzerland

The 1-deoxysphingolipids (1-deoxySLs) are formed by an alternate substrate usage of the enzyme, serine-palmitoyltransferase, and are devoid of the C1-OH-group present in canonical sphingolipids. Pathologically elevated 1-deoxySL levels are associated with the rare inherited neuropathy, HSAN1, and diabetes type 2 and might contribute to β cell failure and the diabetic sensory neuropathy. In analogy to canonical sphingolipids, it was assumed that 1-deoxySLs also bear a (4E) double bond, which is normally introduced by sphingolipid delta(4)-desaturase 1. This, however, was never confirmed. We therefore supplemented HEK293 cells with isotope-labeled D3-1-deoxysphinganine and compared the downstream formed D3-1-deoxysphingosine (1-deoxySO) to a commercial synthetic SPH m18:1(4E)(3OH) standard. Both compounds showed the same m/z, but differed in their RPLC retention time and atmospheric pressure chemical ionization in-source fragmentation, suggesting that the two compounds are structural isomers. Using dimethyl disulfide derivatization followed by MS(2) as well as differential-mobility spectrometry combined with ozone-induced dissociation MS, we identified the carbon-carbon double bond in native 1-deoxySO to be located at the (Δ14) position. Comparing the chromatographic behavior of native 1-deoxySO to chemically synthesized SPH m18:1(14Z) and (14E) stereoisomers assigned the native compound to be SPH m18:1(14Z). This indicates that 1-deoxySLs are metabolized differently than canonical sphingolipids.
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http://dx.doi.org/10.1194/jlr.M067033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4918849PMC
July 2016

1-Deoxysphingolipid-induced neurotoxicity involves N-methyl-d-aspartate receptor signaling.

Neuropharmacology 2016 11 23;110(Pt A):211-222. Epub 2016 Mar 23.

Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland. Electronic address:

1-Deoxysphingolipids (1-deoxySL) are atypical and neurotoxic sphingolipids formed by alternate substrate usage of the enzyme serine-palmitoyltransferase. Pathologically increased 1-deoxySL formation causes hereditary sensory and autosomal neuropathy type 1 (HSAN1) - a progressive peripheral axonopathy. However, the underlying molecular mechanisms by which 1-deoxySL acts are unknown. Herein we studied the effect of 1-deoxysphinganine (1-deoxySA) and its canonical counterpart sphinganine (SA) in aged cultured neurons comparing their outcome on cell survival and cytoskeleton integrity. 1-deoxySA caused rapid neuronal cytoskeleton disruption and modulated important cytoskeletal regulatory and associated components including Rac1, Ezrin and insulin receptor substrate 53. We show that 1-deoxySA is internalized and metabolized downstream to 1-deoxydihydroceramide since inhibition of ceramide synthase protected neurons from 1-deoxySA-mediated cell death. In addition, 1-deoxySA reduced protein levels of N-methyl-d-aspartate receptor (NMDAR) subunit GluN2B, the postsynaptic density protein 95 and induced cleavage of p35 to p25. Notably, blocking NMDAR activation by MK-801 or memantine significantly prevented 1-deoxySA neurotoxicity. Functional studies of differentiating primary neurons via the patch-clamp technique demonstrated that 1-deoxySA irreversibly depolarizes the neuronal membrane potential in an age-dependent manner. Notably, only neuronal cells that displayed functional NMDAR- and NMDA-induced whole-cell currents responded to 1-deoxySA treatment. Furthermore, pre-exposure to the non-competitive antagonist MK-801 blocked the current response of NMDA and glycine, as well as 1-deoxySA. We conclude that 1-deoxySA-induced neurotoxicity compromises cytoskeletal stability and targets NMDAR signaling in an age-dependent manner. Thus stabilization of cytoskeletal structures and/or inhibition of glutamate receptors could be a potential therapeutic approach to prevent 1-deoxySA-induced neurodegeneration.
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http://dx.doi.org/10.1016/j.neuropharm.2016.03.033DOI Listing
November 2016

Viral serine palmitoyltransferase induces metabolic switch in sphingolipid biosynthesis and is required for infection of a marine alga.

Proc Natl Acad Sci U S A 2016 Mar 16;113(13):E1907-16. Epub 2016 Mar 16.

Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot 76100, Israel;

Marine viruses are the most abundant biological entities in the oceans shaping community structure and nutrient cycling. The interaction between the bloom-forming alga Emiliania huxleyi and its specific large dsDNA virus (EhV) is a major factor determining the fate of carbon in the ocean, thus serving as a key host-pathogen model system. The EhV genome encodes for a set of genes involved in the de novo sphingolipid biosynthesis, not reported in any viral genome to date. We combined detailed lipidomic and biochemical analyses to characterize the functional role of this virus-encoded pathway during lytic viral infection. We identified a major metabolic shift, mediated by differential substrate specificity of virus-encoded serine palmitoyltransferase, a key enzyme of sphingolipid biosynthesis. Consequently, unique viral glycosphingolipids, composed of unusual hydroxylated C17 sphingoid bases (t17:0) were highly enriched in the infected cells, and their synthesis was found to be essential for viral assembly. These findings uncover the biochemical bases of the virus-induced metabolic rewiring of the host sphingolipid biosynthesis during the chemical "arms race" in the ocean.
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http://dx.doi.org/10.1073/pnas.1523168113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4822627PMC
March 2016

Decreased phosphatidylcholine plasmalogens--A putative novel lipid signature in patients with stable coronary artery disease and acute myocardial infarction.

Atherosclerosis 2016 Mar 6;246:130-40. Epub 2016 Jan 6.

Institute of Clinical Chemistry, University and University Hospital of Zurich, Zurich, Switzerland; Competence Center for Integrated Human Physiology, University of Zurich, Zurich, Switzerland; Competence Center for Systems Physiology and Metabolic Diseases, ETH Zurich and University of Zurich, Zurich, Switzerland. Electronic address:

Objective: Glycerophospholipids and sphingolipids are structurally heterogeneous due to differences in the O- and N-linked fatty acids and head groups. Sphingolipids also show a heterogeneity in their sphingoid base composition which up to now has been little appreciated. The aim of this study was to investigate the association of certain glycerophospholipid and sphingolipid species with stable coronary artery disease (CAD) and acute myocardial infarction (AMI).

Methods: The lipid profile in plasma from patients with stable CAD (n = 18) or AMI (n = 17) was compared to healthy subjects (n = 14). Sixty five glycerophospholipid and sphingolipid species were quantified by LC-MS. The relative distribution of these lipids into lipoprotein fractions was analyzed.

Results: In the CAD cohort, 45 glycerophospholipid and sphingolipid species were significantly lower compared to healthy controls. In the AMI group, 42 glycerophospholipid and sphingolipid species were reduced. Four PC plasmalogens (PC33:1, PC33:2, PC33:3 and PC35:3) showed the most significant difference. Out of eleven analyzed sphingoid bases, four were lower in the CAD and six in the AMI group. Sphingosine-1-phosphate (S1P) levels were reduced in the AMI group whereas an atypical C16:1 S1P was lower in both groups. Phosphatidylcholine and sphingomyelin species were exclusively present in lipoprotein particles, whereas lysophosphatidylcholines were mainly found in the lipoprotein-free fraction. The observed differences were not explained by the use of statins as confirmed in a second, independent cohort.

Conclusions: Reduced levels of four PC plasmalogens (PC33:1, PC33:2, PC33:3 and PC35:3) were identified as a putatively novel lipid signature for CAD and AMI.
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http://dx.doi.org/10.1016/j.atherosclerosis.2016.01.003DOI Listing
March 2016

HSAN1 mutations in serine palmitoyltransferase reveal a close structure-function-phenotype relationship.

Hum Mol Genet 2016 Mar 17;25(5):853-65. Epub 2015 Dec 17.

Institute for Clinical Chemistry, University Hospital Zurich, Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland, Competence Center for Personalized Medicine (CC-PM), Molecular Translation and Biomedicine (MTB), and

Hereditary sensory and autonomic neuropathy type 1 (HSAN1) is a rare autosomal dominant inherited peripheral neuropathy caused by mutations in the SPTLC1 and SPTLC2 subunits of serine palmitoyltransferase (SPT). The mutations induce a permanent shift in the substrate preference from L-serine to L-alanine, which results in the pathological formation of atypical and neurotoxic 1-deoxy-sphingolipids (1-deoxySL). Here we compared the enzymatic properties of 11 SPTLC1 and six SPTLC2 mutants using a uniform isotope labelling approach. In total, eight SPT mutants (STPLC1p.C133W, p.C133Y, p.S331F, p.S331Y and SPTLC2p.A182P, p.G382V, p.S384F, p.I504F) were associated with increased 1-deoxySL synthesis. Despite earlier reports, canonical activity with l-serine was not reduced in any of the investigated SPT mutants. Three variants (SPTLC1p.S331F/Y and SPTLC2p.I505Y) showed an increased canonical activity and increased formation of C20 sphingoid bases. These three mutations are associated with an exceptionally severe HSAN1 phenotype, and increased C20 sphingosine levels were also confirmed in plasma of patients. A principal component analysis of the analysed sphingoid bases clustered the mutations into three separate entities. Each cluster was related to a distinct clinical outcome (no, mild and severe HSAN1 phenotype). A homology model based on the protein structure of the prokaryotic SPT recapitulated the same grouping on a structural level. Mutations associated with the mild form clustered around the active site, whereas mutations associated with the severe form were located on the surface of the protein. In conclusion, we showed that HSAN1 mutations in SPT have distinct biochemical properties, which allowed for the prediction of the clinical symptoms on the basis of the plasma sphingoid base profile.
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http://dx.doi.org/10.1093/hmg/ddv611DOI Listing
March 2016

Plasma levels of trimethylamine-N-oxide are confounded by impaired kidney function and poor metabolic control.

Atherosclerosis 2015 Dec 24;243(2):638-44. Epub 2015 Oct 24.

Institute of Clinical Chemistry, University Hospital and University of Zurich, Zurich, Switzerland. Electronic address:

Background: After ingestion of phosphatidylcholine, l-carnitine or betaine, trimethylamine-N-oxide (TMAO) is formed by gut microbiota and liver enzymes. Elevated TMAO plasma levels were associated with increased cardiovascular risk and other diseases. Also betaine and choline itself were recently associated with increased cardiovascular risk.

Methods: A newly developed LC-HRMS method was applied to measure the plasma concentrations of TMAO, betaine and choline in a cohort of 339 patients undergoing coronary angiography for the evaluation of suspected coronary artery disease.

Results: Betaine concentrations in males were significantly higher than in females (42.0 vs. 35.9 μmol/L; p < 0.001). Plasma concentrations of TMAO but not of betaine or choline were higher in patients with diabetes compared to euglycemic patients (2.39 vs. 0.980 μmol/L; p = 0.001) as well as in patients with metabolic syndrome as compared to patients without metabolic syndrome (2.37 vs. 1.43 μmol/L; p = 0.002). Plasma concentrations of TMAO or choline increased significantly with decreasing renal function (Spearman's rho: -0.281; p < 0.001). However, plasma levels of TMAO or betaine were associated with neither a history of myocardial infarction nor the angiographically assessed presence of coronary heart disease, nor incident cardiovascular events during 8 years of follow-up. Plasma levels of choline were significantly lower in patients with a history of acute myocardial infarction as compared to those without such history (10.0 vs. 10.8 μmol/L; p = 0.045).

Conclusions: Plasma levels of TMAO are confounded by impaired kidney function and poor metabolic control but are not associated with the history, presence or incidence of symptoms or events of coronary heart disease.
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http://dx.doi.org/10.1016/j.atherosclerosis.2015.10.091DOI Listing
December 2015

Fenofibrate lowers atypical sphingolipids in plasma of dyslipidemic patients: A novel approach for treating diabetic neuropathy?

J Clin Lipidol 2015 Jul-Aug;9(4):568-75. Epub 2015 Apr 4.

Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland; Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland. Electronic address:

Background: The condensation of palmitoyl-CoA and L-Serine is the first step in the de novo formation of sphingolipids and catalyzed by the serine-palmitoyltransferase (SPT). Besides other acyl-CoAs the SPT can also metabolize L-alanine and glycine, which forms an atypical category of neurotoxic 1-deoxy-sphingolipids (1-deoxySL). Several mutations in SPT are associated with pathologically increased 1-deoxySL levels, which cause the inherited sensory neuropathy HSAN1. 1-DeoxySL levels are also elevated in individuals with the metabolic syndrome and diabetes mellitus type II and seem to be involved in the pathology of the diabetic neuropathy.

Objective: In previous studies, we observed a strong correlation between plasma 1-deoxySLs and triglycerides (TGs). We were therefore interested whether lowering plasma TG levels also affects plasma sphingolipid and in particular, 1-deoxySL levels.

Methods: Sixty-six patients with dyslipidemia were treated for 6 wk with the TG-lowering drug fenofibrate (160 mg/d) or extended-release niacin (0.5 g/d for 3 wk, then 1 g/d) with 4 wk of washout between treatments. The sphingoid base profile was analyzed by liquid chromatography-mass spectrometry (LC-MS) before and after each treatment block.

Results: Fenofibrate significantly lowered 1-deoxySLs and other atypical sphingoid bases (P < .001) but had no effect on the typical sphingolipids. In contrast, extended-release niacin had no effect on 1-deoxySL levels although both treatments lowered plasma TG levels.

Conclusions: The lowering of plasma 1-deoxySL levels by fenofibrate in dyslipidemic patients might be a novel therapeutic approach in the prevention and treatment of diabetic neuropathy.
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http://dx.doi.org/10.1016/j.jacl.2015.03.011DOI Listing
May 2016

Neurotoxic 1-deoxysphingolipids and paclitaxel-induced peripheral neuropathy.

FASEB J 2015 Nov 21;29(11):4461-72. Epub 2015 Jul 21.

*Department of Medicine, Department of Biochemistry and Molecular Biology, and Department of Public Health Sciences, Medical University of South Carolina, Charleston, South Carolina, USA; and Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland

Peripheral neuropathy is a major dose-limiting side effect of paclitaxel and cisplatin chemotherapy. In the current study, we tested the involvement of a novel class of neurotoxic sphingolipids, the 1-deoxysphingolipids. 1-Deoxysphingolipids are produced when the enzyme serine palmitoyltransferase uses l-alanine instead of l-serine as its amino acid substrate. We tested whether treatment of cells with paclitaxel (250 nM, 1 µM) and cisplatin (250 nM, 1 µM) would result in elevated cellular levels of 1-deoxysphingolipids. Our results revealed that paclitaxel, but not cisplatin treatment, caused a dose-dependent elevation of 1-deoxysphingolipids levels and an increase in the message and activity of serine palmitoyltransferase (P < 0.05). We also tested whether there is an association between peripheral neuropathy symptoms [evaluated by the European Organization for Research and Treatment of Cancer (EORTC) QLQ-chemotherapy-induced peripheral neuropathy-20 (CIPN20) instrument] and the 1-deoxysphingolipid plasma levels (measured by mass spectrometry) in 27 patients with breast cancer who were treated with paclitaxel chemotherapy. Our results showed that there was an association between the incidence and severity of neuropathy and the levels of very-long-chain 1-deoxyceramides such as C24 (P < 0.05), with the strongest association being with motor neuropathy (P < 0.001). Our data from cells and from patients with breast cancer suggest that 1-deoxysphingolipids, the very-long-chain in particular, play a role as molecular intermediates of paclitaxel-induced peripheral neuropathy.
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http://dx.doi.org/10.1096/fj.15-272567DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4608911PMC
November 2015

Plasmalogens of high-density lipoproteins (HDL) are associated with coronary artery disease and anti-apoptotic activity of HDL.

Atherosclerosis 2015 Aug 9;241(2):539-46. Epub 2015 Jun 9.

Institute of Clinical Chemistry, University and University Hospital of Zurich, Switzerland; Competence Center for Integrated Human Physiology, University of Zurich, Switzerland; Competence Center for Personalized Medicine, ETH Zurich and University of Zurich, Switzerland. Electronic address:

Objective: Low high-density lipoprotein (HDL) cholesterol and loss of atheroprotective functions of HDL are associated with coronary artery disease (CAD). Here, we investigated the associations of HDL phospholipids with acute and stable CAD as well as with the anti-apoptotic activity of HDL.

Methods: 49 species of phosphatidylcholines (PCs), lysophosphatidylcholines and sphingomyelins (SMs) as well as three species of sphingosine-1-phosphate (S1P) were quantified by liquid chromatography - mass spectrometry in HDL isolated from 22 healthy subjects as well as 23 and 22 patients with stable CAD and acute coronary syndrome (ACS), respectively. Native HDL and artificially reconstituted HDL (rHDL) were tested for their capacity to inhibit apoptosis of endothelial cells (ECs) induced by serum deprivation.

Results: HDL of CAD or ACS patients differed from HDL of healthy controls by the content in nine of the 52 quantified phospholipid species as well as reduced anti-apoptotic activity. The capacity of HDL to inhibit EC apoptosis correlated significantly with five of eleven odd-chain PC's (= plasmalogens), two S1P's, SM42:2, PC34:2, and PC32:0. An orthogonal partial least square - discriminant analysis revealed independent associations of stable CAD with HDL-associated PC34:2, PC33:3 and PC35:2 as well as anti-apoptotic activity of HDL and of ACS with HDL-associated PC33:3, PC35:2, SM42:1, PC34:2 and PC36:2. rHDL reconstituted with apoA-I, PC34:1, and PC35:2 inhibited apoptosis of EC's more effectively than rHDL containing only apoA-I and PC34:1.

Conclusions: The inverse association of HDL-plasmalogen levels with both stable and acute CAD may reflect direct anti-apoptotic effects of plasmologens on ECs.
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http://dx.doi.org/10.1016/j.atherosclerosis.2015.05.037DOI Listing
August 2015

Plasma 1-deoxysphingolipids are predictive biomarkers for type 2 diabetes mellitus.

BMJ Open Diabetes Res Care 2015 19;3(1):e000073. Epub 2015 Mar 19.

Institute for Clinical Chemistry, University Hospital Zurich , Zurich , Switzerland ; Centre for Integrative Human Physiology, University of Zurich , Zurich , Switzerland.

Objective: Serine palmitoyltransferase (SPT) catalyzes the condensation of serine and palmitoyl coenzyme A, the first step in the de novo sphingolipid synthesis. Apart from these canonical substrates, SPT can also metabolize alanine and other acyl coenzyme As. This forms a spectrum of atypical sphingoid bases which are altered in the context of the metabolic syndrome (MetS) and type 2 diabetes mellitus (T2DM). We investigated whether atypical sphingolipids can be used as prospective markers to predict the incidence of T2DM.

Research Design And Methods: Using liquid chromatography/mass spectrometry, we analyzed the sphingoid base profile in a prospective cohort with 339 individuals. All individuals were followed up for a period of 8 years.

Results: Confirming earlier results, we found 1-deoxysphingolipids (1-deoxySLs) to be significantly elevated in patients with MetS, impaired fasting glucose, and T2DM. Patients who developed T2DM during the follow-up period (n=32) showed significantly higher 1-deoxySL levels at baseline compared with those who did not develop T2DM until the end of the study (n=70). 1-Deoxysphingosine levels were independent predictors for T2DM even after adjusting for glycated hemoglobin (standardized adjusted OR=2.1, CI 95% (1.19 to 3.71); p=0.010), MetS (standardized adjusted OR=1.97, CI 95% (1.13 to 3.43); p=0.017), and other risk factors such as age, sex, BMI, and lipid-lowering drugs. Similar results were observed for the 1-deoxysphinganine levels.

Conclusions: Our results support a novel role for 1-deoxySL as predictive biomarkers for the development of T2DM in risk patients and warrants further larger prospective trials in lower risk cohorts.
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http://dx.doi.org/10.1136/bmjdrc-2014-000073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4368929PMC
March 2015

Plasma C20-Sphingolipids predict cardiovascular events independently from conventional cardiovascular risk factors in patients undergoing coronary angiography.

Atherosclerosis 2015 May 14;240(1):216-21. Epub 2015 Mar 14.

Institute for Clinical Chemistry, University Hospital Zurich, Rämistrasse 100, 8091 Zurich, Switzerland; Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland. Electronic address:

Aims: Sphingolipids are emerging as novel players in the pathogenesis of atherosclerosis and cardiovascular disease. Serine palmitoyltransferase (SPT) catalyzes the first and rate-limiting step in the de novo synthesis of sphingolipids--the condensation of palmitoyl-CoA and L-Serine. In addition to these canonical substrates, SPT can also metabolize other acyl-CoAs and amino acids, thus generating a variety of atypical sphingoid bases. In this study, we investigated the association of these atypical sphingoid bases with the presence of angiographically characterized coronary artery disease (CAD) as well as their ability to predict the incidence of cardiovascular events.

Methods And Results: 349 subjects, who underwent coronary angiography for the evaluation of established or suspected stable CAD, were enrolled in the study at baseline and followed up for cardiovascular events over a period of 8 years (median 7.7 years). The sphingoid base profile in the extracted plasma sphingolipids were determined by LC/MS after acid-base hydrolysis. Plasma levels of C18SAdiene were found to be significantly lower in CAD patients at baseline, while levels for C16SA, C16SO, C17SO, C18SA, C18SO, and C19SO and 1-deoxy sphingoid bases were not different. In the prospective analysis C20SO significantly predicted cardiovascular events (standardized adjusted HR=1.20, CI 95% [1.03-1.41]; p=0.022) after adjusting for traditional risk factors, the use of lipid-lowering drugs and angiographically-determined CAD at baseline.

Conclusion: Plasma C20SO levels are independent predictive biomarkers for cardiovascular events, even after adjusting for cardiovascular risk factors including coronary stenosis.
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http://dx.doi.org/10.1016/j.atherosclerosis.2015.03.011DOI Listing
May 2015