Refine
Has Fulltext
- no (102) (remove)
Year of publication
Document Type
- Article (102) (remove)
Language
- English (102)
Is part of the Bibliography
- yes (102)
Keywords
- acid sphingomyelinase (9)
- ceramide (9)
- Sphingolipids (7)
- sphingolipids (7)
- Dexamethasone (5)
- Sphingosine 1-phosphate (5)
- acid ceramidase (4)
- Drug delivery systems (3)
- Insulin resistance (3)
- Sphingosine-1-phosphate (3)
- sphingosine (3)
- sphingosine-1-phosphate (3)
- Acid sphingomyelinase (2)
- Biomarker (2)
- Ceramide (2)
- Clinical (2)
- DNA methylation (2)
- Dendritic cells (2)
- Dermal delivery (2)
- Drug delivery (2)
- FTY720 (2)
- Farber disease (2)
- Fluorescence lifetime imaging microscopy (2)
- Gestational diabetes (2)
- Global DNA methylation (2)
- Hepatocytes (2)
- LC-MS/MS (2)
- Metabolomics (2)
- Nanoparticle (2)
- Nanoparticle uptake (2)
- Nanotoxicology (2)
- Palmitate (2)
- Placenta (2)
- Pseudomonas aeruginosa (2)
- Skin nanocarrier (2)
- Skin penetration (2)
- Tandem mass spectrometry (2)
- Ulcerative colitis (2)
- amitriptyline (2)
- cystic fibrosis (2)
- liver metabolism (2)
- lysosomal storage disorders (2)
- measles virus (2)
- platelets (2)
- sphingomyelin (2)
- survival (2)
- (2E)-Hexadecenal (1)
- (2E)-hexadecenal (1)
- (2E)-hexadecenoic acid (1)
- 1-aminodecylidene bis-phosphonic acid (1)
- 1-phosphate (1)
- 3D tissue model (1)
- APOM protein (1)
- Acinetobacter baumannii (1)
- Adipocytes (1)
- Adipose tissue (1)
- Aging (1)
- Akt (1)
- Akt signaling (1)
- Alcohol dependence (1)
- Anxiety (1)
- Apoptosis (1)
- Arsenic speciation (1)
- Arsenic-containing hydrocarbons (1)
- Arsenolipids (1)
- Aryl-hydrocarbon receptor (1)
- Atherosclerosis (1)
- Atopic dermatitis (1)
- Autotaxin (1)
- B cells (1)
- Biocompatibility (1)
- Biocompatibility testing (1)
- Blood platelets (1)
- Broad-spectrum antibiotic therapy (1)
- Brown adipose tissue (1)
- CMS (1)
- CXCR2 (1)
- Caenorhabditis elegans (1)
- Cardiovascular (1)
- Case-control study (1)
- Cellular uptake (1)
- Cellulose acetate phthalate (1)
- Ceramidase inhibitors (1)
- Ceramides (1)
- Chemotherapy resistance (1)
- Citrobacter rodentium (1)
- Coating (1)
- Colitis (1)
- Colon cancer (1)
- Core-multishell nanocarriers (1)
- Cyp2b1 (1)
- DAIH (1)
- DNMT inhibitor (1)
- Delta F508 mutation (1)
- Dendritic core-multishell nanocarriers (1)
- Dengue (1)
- Depression (1)
- Derivatisation (1)
- Derivatization (1)
- Dermal drug delivery (1)
- Diagnostic (1)
- Dichlorofluorescein assay (1)
- Disease (1)
- Dolichol lipids (1)
- Dopamine (1)
- EBI3 (1)
- EDC (1)
- Electron paramagnetic resonance spectroscopy (1)
- Endocrine disruption (1)
- Endothelial cells (1)
- Endothelial nitric oxide synthase (1)
- Energy expenditure (1)
- Enteric polymer (1)
- Epigenetic (1)
- Epigenetics (1)
- Erosion kinetics (1)
- Ethyl cellulose (1)
- Eudragit (R) (1)
- Eudragit (R) RS (1)
- Eudragit L 100 (1)
- FGF21 (1)
- Factor-Xa (1)
- Fetal programming (1)
- Fingolimod (1)
- Fluorescence (1)
- Forster resonance energy transfer (FRET) (1)
- Free radicals (1)
- Gastrointestinal tract (1)
- Gene expression (1)
- Global (1)
- Glp1r(-/-) mice (1)
- Glutathione (1)
- Glycerophospholipids (1)
- HNRNPA1 (1)
- HPLC-ESI-QTOF (1)
- HPMCP (1)
- HaCaT cells (1)
- Hepatic insulin resistance (1)
- Hepatic stellate cells (1)
- High resolution microscopy (1)
- Histone deacetylase inhibitor (1)
- Human (1)
- Hyperglycaemia (1)
- Hypermethylation (1)
- IDH1 (1)
- Imiquimod (1)
- Inflammatory skin disease (1)
- Inhibitory cytokines (1)
- Insulin signaling (1)
- Insulin signalling (1)
- Interleukin-35 (1)
- Ischemia/reperfusion (1)
- Isotope-dilution (1)
- Isotope-dilution analysis (1)
- Jurkat cells (1)
- Keratinocytes (1)
- LPA(3) receptor subtype (1)
- Langerhans cells (1)
- Lipogenesis (1)
- Liquid chromatography-tandem mass spectrometry (1)
- Liver (1)
- Liver fibrosis (1)
- Liver injury (1)
- Lysophosphatidic acid (1)
- Lysophosphatidylcholines (1)
- Mass spectrometry (1)
- Metabolism (1)
- Methylation (1)
- Microbiota (1)
- Microdialysis (1)
- Multi-domain nanoparticles (1)
- Multiple sclerosis (1)
- NZO (1)
- Nanogel (1)
- Nanomaterials (1)
- Nanoparticles (1)
- Neisseria gonorrhoeae (1)
- Nitric oxide (1)
- Obesity (1)
- Ocular delivery (1)
- Oxazolone (1)
- Oxidative stress (1)
- PCaaC38:6 (1)
- PTEN (1)
- Penetration enhancement (1)
- Permeability (1)
- Phosphatidylcholine acyl-alkyl C 32:1 (1)
- Phosphatidylcholines (1)
- Phosphatidylinositols (1)
- Plasma (1)
- Plasmalogens (1)
- Plastic surfaces (1)
- Poly[acrylonitrile-co-(N-vinyl pyrrolidone)] (1)
- Polymeric nanoparticle (1)
- Polymeric nanoparticles (1)
- Polymers (1)
- Pregnancy (1)
- Preterm birth (1)
- Proliferation (1)
- Proline (1)
- Protein restriction (1)
- Psoriasis (1)
- Retinoblastoma (1)
- S1P receptors (1)
- S1P-receptors (1)
- SAHA (1)
- SCID mice (1)
- ST-1071 (1)
- ST-1893 (1)
- ST-1894 (1)
- ST-968 (1)
- Selenium (1)
- Serotonin (1)
- Skeletal muscle cells (1)
- Skin (1)
- Skin absorption (1)
- Skin barrier disruption (1)
- Skin model (1)
- Smooth muscle cells (1)
- Smpd1 (1)
- Sphingomyelin (1)
- Sphingosine (1)
- Sphingosine 1phosphate (1)
- Sphingosine kinase (1)
- Sphingosine kinase-1 (1)
- Sphingosine-1-phosphate lyase (1)
- Srebf1 (1)
- Staphylococcus aureus (1)
- Structure-activity-relationship (1)
- T cell receptor (1)
- T(h)1 (1)
- T(h)17 (1)
- TET (1)
- TGF-beta 1 (1)
- TNF alpha (1)
- TRPC6 (1)
- Thyroid hormone (1)
- Topical treatment (1)
- Transplantation (1)
- Type 2 diabetes (1)
- UDP-glucuronosyltransferase (1)
- Ventilation (1)
- Ventilator-induced lung injury (1)
- Vitamin C (1)
- Xenobesity (1)
- YB-1 (1)
- acid ceramidase inhibitor ceranib-2 (1)
- acute lung injury (1)
- alpha-SMA (1)
- annexins (1)
- anti-inflammatory therapy (1)
- anticancer (1)
- antidepressants (1)
- anxiety-like behavior (1)
- appetite (1)
- autoimmunity (1)
- bacterial toxins (1)
- binding (1)
- birth weight (1)
- bisphosphonates (1)
- blebbing (1)
- blood banking (1)
- brain insulin signaling (1)
- burn injury (1)
- c. elegans (1)
- calcium (1)
- cancer cells (1)
- cell migration (1)
- cells (1)
- cerami-des (1)
- ceramides (1)
- cholesteryl ester (1)
- chronic kidney disease (1)
- chronic psychosocial stress (1)
- chronic subordinate colony housing (CSC) (1)
- circulation (1)
- click chemistry (1)
- colitis (1)
- collagen I (1)
- decitabine (1)
- dendritic cell (1)
- depressive-like behavior (1)
- diacylglycerol (1)
- disease (1)
- distress (1)
- drug delivery (1)
- drug design (1)
- drug metabolism (1)
- dysfunction (1)
- enzyme assays (1)
- enzymology (1)
- epigenetics (1)
- etanercept (1)
- experimental antigen-induced encephalomyelitis (1)
- extinction (1)
- fatty acid metabolism (1)
- fetal origins hypothesis (1)
- fibrosis (1)
- fingolimod (1)
- force-field (1)
- forebrain (1)
- functional inhibitors of acid sphin-gomyelinase (1)
- genes (1)
- glucocorticoid receptor (1)
- growth restriction (1)
- high density (1)
- hippocampus (1)
- human excised skin (1)
- hyperforin (1)
- immune (1)
- immunology (1)
- immunomodulator (1)
- immunonutrition (1)
- infection (1)
- inhibitory cytokines (1)
- integrins (1)
- interleukin-35 (1)
- intestine (1)
- invasion (1)
- keratinocytes (1)
- later health (1)
- life-span (1)
- linagliptin (1)
- lipid metabolism (1)
- lipid rafts (1)
- lipoproteins (1)
- liposomes (1)
- long chain base (1)
- lung cancer (1)
- lung infection (1)
- lung inflammation (1)
- lymphopenia (1)
- lyso-phospholipids (1)
- lysosomal hydrolases (1)
- lysosome (1)
- mass spectrometry (1)
- membrane fusion (1)
- membrane lipids (1)
- membrane repair (1)
- membrane-lipid therapy (1)
- menadione (1)
- microparticle (1)
- migration (1)
- mitochondria (1)
- molecular dynamics (1)
- molecular modeling (1)
- morpholino analogues of fingolimod (1)
- mortality (1)
- multiple sclerosis (1)
- n-acetyl-cysteine (1)
- nanogels (1)
- nanoparticles (1)
- nanotoxicology (1)
- neutral sphingomyelinase-2 (1)
- neutrophil chemotaxis (1)
- nutrient transport (1)
- operant behavior (1)
- oxidative stress (1)
- pH-sensitive nanoparticle (1)
- pH-sensitive nanoparticles (1)
- particle characterization (1)
- patterns (1)
- phagocytosis (1)
- plasma membrane (1)
- pneumococcal pneumonia (1)
- pregnancy (1)
- primary immunodeficiencies (1)
- proliferation (1)
- protein (1)
- proteomic analysis (1)
- refinement (1)
- repetitive elements (1)
- s-glutathionylation (1)
- serine palmitoyltransferase (1)
- skin equivalents (1)
- skin penetration (1)
- sphingolipid de novo synthesis (1)
- sphingolipid metabolism (1)
- sphingosine kinase (1)
- sphingosine kinase 1 (1)
- sphingosine kinase inhibitor SKI-II (1)
- sphingosine kinases (1)
- sphingosine-1-phosphate receptor 2 (1)
- stable-isotope labeling (1)
- storage (1)
- sulfotransferase (1)
- tacrolimus formulation (1)
- thermoresponsive-nanogel (1)
- thymosin beta 4 (1)
- topical (1)
- transfusion-related acute lung injury (1)
- transport proteins (1)
- tumor-metastasis (1)
- type 2 diabetes mellitus (1)
Institute
Gram-positive bacterial pathogens that secrete cytotoxic pore-forming toxins, such as Staphylococcus aureus and Streptococcus pneumoniae, cause a substantial burden of disease. Inspired by the principles that govern natural toxin-host interactions, we have engineered artificial liposomes that are tailored to effectively compete with host cells for toxin binding. Liposome-bound toxins are unable to lyse mammalian cells in vitro. We use these artificial liposomes as decoy targets to sequester bacterial toxins that are produced during active infection in vivo. Administration of artificial liposomes within 10 h after infection rescues mice from septicemia caused by S. aureus and S. pneumoniae, whereas untreated mice die within 24-33 h. Furthermore, liposomes protect mice against invasive pneumococcal pneumonia. Composed exclusively of naturally occurring lipids, tailored liposomes are not bactericidal and could be used therapeutically either alone or in conjunction with antibiotics to combat bacterial infections and to minimize toxin-induced tissue damage that occurs during bacterial clearance.
Glucolipotoxic stress has been identified as a key player in the progression of pancreatic beta-cell dysfunction contributing to insulin resistance and the development of type 2 diabetes mellitus (T2D). It has been suggested that bioactive lipid intermediates, formed under lipotoxic conditions, are involved in these processes. Here, we show that sphingosine 1-phosphate (S1P) levels are not only increased in palmitate-stimulated pancreatic beta-cells but also regulate beta-cell homeostasis in a divergent manner. Although S1P possesses a prosurvival effect in beta-cells, an enhanced level of the sphingolipid antagonizes insulin-mediated cell growth and survival via the sphingosine 1-phosphate receptor subtype 2 (S1P(2)) followed by an inhibition of Akt-signaling. In an attempt to investigate the role of the S1P/S1P(2) axis in vivo, the New Zealand obese (NZO) diabetic mouse model, characterized by beta-cell loss under high-fat diet (HFD) conditions, was used. The occurrence of T2D was accompanied by an increase of plasma S1P levels. To examine whether S1P contributes to the morphologic changes of islets via S1P(2), the receptor antagonist JTE-013 was administered. Most interestingly, JTE-013 rescued beta-cell damage clearly indicating an important role of the S1P(2) in beta-cell homeostasis. Therefore, the present study provides a new therapeutic strategy to diminish beta-cell dysfunction and the development of T2D.
Background: A transient endothelial hyperpermeability is a hallmark of severe dengue infections. Sphingosine-1-phosphate (S1P) maintains vascular integrity and protects against plasma leakage. We related plasma S1P levels to dengue-induced plasma leakage and studied mechanisms that may underlie the decrease in S1P levels in dengue.
Methods: We determined circulating levels of S1P in 44 Indonesian adults with acute dengue and related levels to plasma leakage, as determined by daily ultrasonography, and to levels of its chaperone apolipoprotein M, other lipoproteins and platelets.
Results: Plasma S1P levels were decreased during dengue and patients with plasma leakage had lower median levels compared to those without (638 vs. 745 nM; p < 0.01). ApoM and other lipoprotein levels were also decreased during dengue, but did not correlate to S1P levels. Platelet counts correlated positively with S1P levels, but S1P levels were not higher in frozen-thawed platelet rich plasma, arguing against platelets as an important cellular source of S1P in dengue.
Conclusions: Decreased plasma S1P levels during dengue are associated with plasma leakage. We speculate that decreased levels of ApoM underlies the lower S1P levels. Modulation of S1P levels and its receptors may be a novel therapeutic intervention to prevent plasma leakage in dengue. (C) 2015 The British Infection Association. Published by Elsevier Ltd. All rights reserved.
Metastatic dissemination of cancer cells is the ultimate hallmark of malignancy and accounts for approximately 90% of human cancer deaths. We investigated the role of acid sphingomyelinase (Asm) in the hematogenous metastasis of melanoma cells. Intravenous injection of B16F10 melanoma cells into wild-type mice resulted in multiple lung metastases, while Asm-deficient mice (Smpd1(-/-) mice) were protected from pulmonary tumor spread. Transplanting wild-type platelets into Asm-deficient mice reinstated tumor metastasis. Likewise, Asm-deficient mice were protected from hematogenous MT/ret melanoma metastasis to the spleen in a mouse model of spontaneous tumor metastasis. Human and mouse melanoma cells triggered activation and release of platelet secretory Asm, in turn leading to ceramide formation, clustering, and activation of 51 integrins on melanoma cells finally leading to adhesion of the tumor cells. Clustering of integrins by applying purified Asm or C-16 ceramide to B16F10 melanoma cells before intravenous injection restored trapping of tumor cells in the lung in Asm-deficient mice. This effect was revertable by arginine-glycine-aspartic acid peptides, which are known inhibitors of integrins, and by antibodies neutralizing 1 integrins. These findings indicate that melanoma cells employ platelet-derived Asm for adhesion and metastasis.
Reward-dependent instrumental behavior must continuously be re-adjusted according to environmental conditions. Failure to adapt to changes in reward contingencies may incur psychiatric disorders like anxiety and depression. When an expected reward is omitted, behavior undergoes extinction. While extinction involves active re-learning, it is also accompanied by emotional behaviors indicative of frustration, anxiety, and despair (extinction-induced depression). Here, we report evidence for a sphingolipid mechanism in the extinction of behavior. Rapid extinction, indicating efficient re-learning, coincided with a decrease in the activity of the enzyme acid sphingomyelinase (ASM), which catalyzes turnover of sphingomyelin to ceramide, in the dorsal hippocampus of rats. The stronger the decline in ASM activity, the more rapid was the extinction. Sphingolipid-focused lipidomic analysis showed that this results in a decline of local ceramide species in the dorsal hippocampus. Ceramides shape the fluidity of lipid rafts in synaptic membranes and by that way can control neural plasticity. We also found that aging modifies activity of enzymes and ceramide levels in selective brain regions. Aging also changed how the chronic treatment with corticosterone (stress) or intranasal dopamine modified regional enzyme activity and ceramide levels, coinciding with rate of extinction. These data provide first evidence for a functional ASM-ceramide pathway in the brain involved in the extinction of learned behavior. This finding extends the known cellular mechanisms underlying behavioral plasticity to a new class of membrane-located molecules, the sphingolipids, and their regulatory enzymes, and may offer new treatment targets for extinction- and learning-related psychopathological conditions.
CD4(+) Foxp3(+) regulatory T cells (Tregs) depend on CD28 signaling for their survival and function, a receptor that has been previously shown to activate the acid sphingomyelinase (Asm)/ceramide system. In this article, we show that the basal and CD28-induced Asm activity is higher in Tregs than in conventional CD4(+) T cells (Tconvs) of wild-type (wt) mice. In Asm-deficient (Smpd1(-/-); Asm(-/-)) mice, as compared with wt mice, the frequency of Tregs among CD4(+) T cells, turnover of the effector molecule CTLA-4, and their suppressive activity in vitro were increased. The biological significance of these findings was confirmed in our Treg-sensitive mouse model of measles virus (MV) CNS infection, in which we observed more infected neurons and less MV-specific CD8(+) T cells in brains of Asm(-/-) mice compared with wt mice. In addition to genetic deficiency, treatment of wt mice with the Asm inhibitor amitriptyline recapitulated the phenotype of Asm-deficient mice because it also increased the frequency of Tregs among CD4(+) T cells. Reduced absolute cell numbers of Tconvs after inhibitor treatment in vivo and extensive in vitro experiments revealed that Tregs are more resistant toward Asm inhibitor-induced cell death than Tconvs. Mechanistically, IL-2 was capable of providing crucial survival signals to the Tregs upon inhibitor treatment in vitro, shifting the Treg/Tconv ratio to the Treg side. Thus, our data indicate that Asm-inhibiting drugs should be further evaluated for the therapy of inflammatory and autoimmune disorders.
Exosomes are small membrane vesicles released by different cell types, including hepatocytes, that play important roles in intercellular communication. We have previously demonstrated that hepatocyte-derived exosomes contain the synthetic machinery to form sphingosine-1-phosphate (S1P) in target hepatocytes resulting in proliferation and liver regeneration after ischemia/reperfusion (I/R) injury. We also demonstrated that the chemokine receptors, CXCR1 and CXCR2, regulate liver recovery and regeneration after I/R injury. In the current study, we sought to determine if the regulatory effects of CXCR1 and CXCR2 on liver recovery and regeneration might occur via altered release of hepatocyte exosomes. We found that hepatocyte release of exosomes was dependent upon CXCR1 and CXCR2. CXCR1-deficient hepatocytes produced fewer exosomes, whereas CXCR2-deficient hepatocytes produced more exosomes compared to their wild-type controls. In CXCR2-deficient hepatocytes, there was increased activity of neutral sphingomyelinase (Nsm) and intracellular ceramide. CXCR1-deficient hepatocytes had no alterations in Nsm activity or ceramide production. Interestingly, exosomes from CXCR1-deficient hepatocytes had no effect on hepatocyte proliferation, due to a lack of neutral ceramidase and sphingosine kinase. The data demonstrate that CXCR1 and CXCR2 regulate hepatocyte exosome release. The mechanism utilized by CXCR1 remains elusive, but CXCR2 appears to modulate Nsm activity and resultant production of ceramide to control exosome release. CXCR1 is required for packaging of enzymes into exosomes that mediate their hepatocyte proliferative effect.
Chronic psychosocial stress adversely affects human morbidity and is a risk factor for inflammatory disorders, liver diseases, obesity, metabolic syndrome, and major depressive disorder (MDD). In recent studies, we found an association of MDD with an increase of acid sphingomyelinase (ASM) activity. Thus, we asked whether chronic psychosocial stress as a detrimental factor contributing to the emergence of MDD would also affect ASM activity and sphingolipid (SL) metabolism. To induce chronic psychosocial stress in male mice we employed the chronic subordinate colony housing (CSC) paradigm and compared them to non-stressed single housed control (SHC) mice. We determined Asm activity in liver and serum, hepatic SL concentrations as well as hepatic mRNA expression of genes involved in SL metabolism. We found that hepatic Asm activity was increased by 28% (P = 0.006) and secretory Asm activity by 47% (P = 0.002) in stressed mice. C16:0-Cer was increased by 40% (P = 0.008). Gene expression analysis further revealed an increased expression of tumor necrosis factor (TNF)-alpha (P = 0.009) and of several genes involved in SL metabolism (Cers5, P = 0.028; Cers6, P = 0.045; Gba, P = 0.049; Gba2, P = 0.030; Ormdl2, P = 0.034; Smpdl3B; P = 0.013). Our data thus provides first evidence that chronic psychosocial stress, at least in mice, induces alterations in SL metabolism, which in turn might be involved in mediating the adverse health effects of chronic psychosocial stress and peripheral changes occurring in mood disorders.
Background & Aims: Exosomes are small membrane vesicles involved in intercellular communication. Hepatocytes are known to release exosomes, but little is known about their biological function. We sought to determine if exosomes derived from hepatocytes contribute to liver repair and regeneration after injury. Methods: Exosomes derived from primary murine hepatocytes were isolated and characterized biochemically and biophysically. Using cultures of primary hepatocytes, we tested whether hepatocyte exosomes induced proliferation of hepatocytes in vitro. Using models of ischemia/reperfusion injury and partial hepatectomy, we evaluated whether hepatocyte exosomes promote hepatocyte proliferation and liver regeneration in vivo. Results: Hepatocyte exosomes, but not exosomes from other liver cell types, induce dose-dependent hepatocyte proliferation in vitro and in vivo. Mechanistically, hepatocyte exosomes directly fuse with target hepatocytes and transfer neutral ceramidase and sphingosine kinase 2 (SK2) causing increased synthesis of sphingosine-1-phosphate (S1P) within target hepatocytes. Ablation of exosomal SK prevents the proliferative effect of exosomes. After ischemia/reperfusion injury, the number of circulating exosomes with proliferative effects increases. Conclusions: Our data shows that hepatocyte-derived exosomes deliver the synthetic machinery to form S1P in target hepatocytes resulting in cell proliferation and liver regeneration after ischemia/reperfusion injury or partial hepatectomy. These findings represent a potentially novel new contributing mechanism of liver regeneration and have important implications for new therapeutic approaches to acute and chronic liver disease. (C) 2015 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.
Involvement of Sphingosine 1-Phosphate in Palmitate-Induced Non-Alcoholic Fatty Liver Disease
(2016)
Background/Aims: Ectopic lipid accumulation in hepatocytes has been identified as a risk factor for the progression of liver fibrosis and is strongly associated with obesity. In particular, the saturated fatty acid palmitate is involved in initiation of liver fibrosis via formation of secondary metabolites by hepatocytes that in turn activate hepatic stellate cells (HSCs) in a paracrine manner Methods: a-smooth muscle actin-expression (alpha-SMA) as a marker of liver fibrosis was investigated via western blot analysis and immunofluorescence microscopy in HSCs (LX-2). Sphingolipid metabolism and the generation of the bioactive secondary metabolite sphingosine I-phosphate (SIP) in response to palmitate were analyzed by LC-MS/MS in hepatocytes (HepG2). To identify the molecular mechanism involved in the progression of liver fibrosis real-time PCR analysis and pharmacological modulation of SIP receptors were performed. Results: Palmitate oversupply increased intra- and extracellular SIP-concentrations in hepatocytes. Conditioned medium from HepG2 cells initiated fibrosis by enhancing alpha-SMA-expression in LX-2 in a S1P-dependent manner In accordance, fibrotic response in the presence of SIP was also observed in HSCs. Pharmacological inhibition of SIP receptors demonstrated that S1P(3) is the crucial receptor subtype involved in this process. Conclusion: SIP is synthesized in hepatocytes in response to palmitate and released into the extracellular environment leading to an activation of HSCs via the S1P(3) receptor (C) 2016 The Author(s) Published by S. Karger AG, Basel
Aims/hypothesis Low-protein diets are well known to improve glucose tolerance and increase energy expenditure. Increases in circulating fibroblast growth factor 21 (FGF21) have been implicated as a potential underlying mechanism. Methods We aimed to test whether low-protein diets in the context of a high-carbohydrate or high-fat regimen would also protect against type 2 diabetes in New Zealand Obese (NZO) mice used as a model of polygenetic obesity and type 2 diabetes. Mice were placed on high-fat diets that provided protein at control (16 kJ%; CON) or low (4 kJ%; low-protein/high-carbohydrate [LP/HC] or low-protein/high-fat [LP/HF]) levels. Results Protein restriction prevented the onset of hyperglycaemia and beta cell loss despite increased food intake and fat mass. The effect was seen only under conditions of a lower carbohydrate/fat ratio (LP/HF). When the carbohydrate/fat ratio was high (LP/HC), mice developed type 2 diabetes despite the robustly elevated hepatic FGF21 secretion and increased energy expenditure. Conclusion/interpretation Prevention of type 2 diabetes through protein restriction, without lowering food intake and body fat mass, is compromised by high dietary carbohydrates. Increased FGF21 levels and elevated energy expenditure do not protect against hyperglycaemia and type 2 diabetes per se.
Acid sphingomyelinase mediates murine acute lung injury following transfusion of aged platelets
(2017)
Pulmonary complications from stored blood products are the leading cause of mortality related to transfusion. Transfusion-related acute lung injury is mediated by antibodies or bioactive mediators, yet underlying mechanisms are incompletely understood. Sphingolipids such as ceramide regulate lung injury, and their composition changes as a function of time in stored blood. Here, we tested the hypothesis that aged platelets may induce lung injury via a sphingolipid-mediated mechanism. To assess this hypothesis, a two-hit mouse model was devised. Recipient mice were treated with 2 mg/kg intraperitoneal lipopolysaccharide (priming) 2 h before transfusion of 10 ml/kg stored (1-5 days) platelets treated with or without addition of acid sphingomyelinase inhibitor ARC39 or platelets from acid sphingomyelinase-deficient mice, which both reduce ceramide formation. Transfused mice were examined for signs of pulmonary neutrophil accumulation, endothelial barrier dysfunction, and histological evidence of lung injury. Sphingolipid profiles in stored platelets were analyzed by mass spectrophotometry. Transfusion of aged platelets into primed mice induced characteristic features of lung injury, which increased in severity as a function of storage time. Ceramide accumulated in platelets during storage, but this was attenuated by ARC39 or in acid sphingomyelinase-deficient platelets. Compared with wild-type platelets, transfusion of ARC39-treated or acid sphingomyelinase-deficient aged platelets alleviated lung injury. Aged platelets elicit lung injury in primed recipient mice, which can be alleviated by pharmacological inhibition or genetic deletion of acid sphingomyelinase. Interventions targeting sphingolipid formation represent a promising strategy to increase the safety and longevity of stored blood products.
Objective: We aimed to identify the role of the enzyme acid sphingomyelinase in the aging of stored units of packed red blood cells (pRBCs) and subsequent lung inflammation after transfusion.
Summary Background Data: Large volume pRBC transfusions are associated with multiple adverse clinical sequelae, including lung inflammation. Microparticles are formed in stored pRBCs over time and have been shown to contribute to lung inflammation after transfusion.
Methods: Human and murine pRBCs were stored with or without amitriptyline, a functional inhibitor of acid sphingomyelinase, or obtained from acid sphingomyelinase-deficient mice, and lung inflammation was studied in mice receiving transfusions of pRBCs and microparticles isolated from these units.
Results: Acid sphingomyelinase activity in pRBCs was associated with the formation of ceramide and the release of microparticles. Treatment of pRBCs with amitriptyline inhibited acid sphingomyelinase activity, ceramide accumulation, and microparticle production during pRBC storage. Transfusion of aged pRBCs or microparticles isolated from aged blood into mice caused lung inflammation. This was attenuated after transfusion of pRBCs treated with amitriptyline or from acid sphingomyelinase-deficient mice.
Conclusions: Acid sphingomyelinase inhibition in stored pRBCs offers a novel mechanism for improving the quality of stored blood.
Background: Abdominal aortic aneurysm (AAA) is a deadly irreversible weakening and distension of the abdominal aortic wall. The pathogenesis of AAA remains poorly understood. Investigation into the physical and molecular characteristics of perivascular adipose tissue (PVAT) adjacent to AAA has not been done before and is the purpose of this study.
Methods and Results: Human aortae, periaortic PVAT, and fat surrounding peripheral arteries were collected from patients undergoing elective surgical repair of AAA. Control aortas were obtained from recently deceased healthy organ donors with no known arterial disease. Aorta and PVAT was found in AAA to larger extent compared with control aortas. Immunohistochemistry revealed neutrophils, macrophages, mast cells, and T-cells surrounding necrotic adipocytes. Gene expression analysis showed that neutrophils, mast cells, and T-cells were found to be increased in PVAT compared with AAA as well as cathepsin K and S. The concentration of ceramides in PVAT was determined using mass spectrometry and correlated with content of T-cells in the PVAT.
Conclusions: Our results suggest a role for abnormal necrotic, inflamed, proteolytic adipose tissue to the adjacent aneurysmal aortic wall in ongoing vascular damage.
Being born large for gestational age is associated with increased global placental DNA methylation
(2020)
Being born small (SGA) or large for gestational age (LGA) is associated with adverse birth outcomes and metabolic diseases in later life of the offspring. It is known that aberrations in growth during gestation are related to altered placental function. Placental function is regulated by epigenetic mechanisms such as DNA methylation. Several studies in recent years have demonstrated associations between altered patterns of DNA methylation and adverse birth outcomes. However, larger studies that reliably investigated global DNA methylation are lacking. The aim of this study was to characterize global placental DNA methylation in relationship to size for gestational age. Global DNA methylation was assessed in 1023 placental samples by LC-MS/MS. LGA offspring displayed significantly higher global placental DNA methylation compared to appropriate for gestational age (AGA; p<0.001). ANCOVA analyses adjusted for known factors impacting on DNA methylation demonstrated an independent association between placental global DNA methylation and LGA births (p<0.001). Tertile stratification according to global placental DNA methylation levels revealed a significantly higher frequency of LGA births in the third tertile. Furthermore, a multiple logistic regression analysis corrected for known factors influencing birth weight highlighted an independent positive association between global placental DNA methylation and the frequency of LGA births (p=0.001).
The visceral protein transthyretin (TTR) is frequently affected by oxidative post-translational protein modifications (PTPMs) in various diseases. Thus, better insight into structure-function relationships due to oxidative PTPMs of TTR should contribute to the understanding of pathophysiologic mechanisms. While the in vivo analysis of TTR in mammalian models is complex, time-and resource-consuming, transgenic Caenorhabditis elegans expressing hTTR provide an optimal model for the in vivo identification and characterization of drug-mediated oxidative PTPMs of hTTR by means of matrix assisted laser desorption/ionization - time of flight - mass spectrometry (MALDI-TOF-MS). Herein, we demonstrated that hTTR is expressed in all developmental stages of Caenorhabditis elegans, enabling the analysis of hTTR metabolism during the whole life-cycle. The suitability of the applied model was verified by exposing worms to D-penicillamine and menadione. Both drugs induced substantial changes in the oxidative PTPM pattern of hTTR. Additionally, for the first time a covalent binding of both drugs with hTTR was identified and verified by molecular modelling.
Loss of pdr-1/parkin influences Mn homeostasis through altered ferroportin expression in C-elegans
(2015)
Dopamine (DA) and serotonin (SRT) are monoamine neurotransmitters that play a key role in regulating the central and peripheral nervous system. Their impaired metabolism has been implicated in several neurological disorders, such as Parkinson's disease and depression. Consequently, it is imperative to monitor changes in levels of these low-abundant neurotransmitters and their role in mediating disease. For the first time, a rapid, specific and sensitive isotope-dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of DA and SRT in the nematode Caenorhabditis elegans (C. elegans). This model organism offers a unique approach for studying the effect of various drugs and environmental conditions on neurotransmitter levels, given by the conserved DA and SRT biology, including synaptic release, trafficking and formation. We introduce a novel sample preparation protocol incorporating the usage of sodium thiosulfate in perchloric acid as extraction medium that assures high recovery of the relatively unstable neurotransmitters monitored. Moreover, the use of both deuterated internal standards and the multiple reaction monitoring (MRM) technique allows for unequivocal quantification. Thereby, to the best of our knowledge, we achieve a detection sensitivity that clearly exceeds those of published DA and SRT quantification methods in various matrices. We are the first to show that exposure of C elegans to the monoamine oxidase B (MAOB) inhibitor selegiline or the catechol-O-methyltransferase (COMT) inhibitor tolcapone, in order to block DA and SRT degradation, resulted in accumulation of the respective neurotransmitter. Assessment of a behavioral output of the dopaminergic system (basal slowing response) corroborated the analytical LC-MS/MS data. Thus, utilization of the C elegans model system in conjunction with our analytical method is well-suited to investigate drug-mediated modulation of the DA and SRT system in order to identify compounds with neuroprotective or regenerative properties. (C) 2015 Elsevier B.V. All rights reserved.
Infection is a common and often deadly complication after burn injury. A major underlying factor is burn-induced immune dysfunction, particularly with respect to neutrophils as the primary responders to infection. Temporally after murine scald injury, we demonstrate impaired bone marrow neutrophil chemotaxis toward CXCL1 ex vivo. Additionally, we observed a reduced recruitment of neutrophils to the peritoneal after elicitation 7 days after injury. We demonstrate that neutrophil ceramide levels increase after burn injury, and this is associated with decreased expression of CXCR2 and blunted chemotaxis. A major signaling event upon CXCR2 activation is Akt phosphorylation and this was reduced when ceramide was elevated. In contrast, PTEN levels were elevated and PTEN-inhibition elevated phospho-Akt levels and mitigated the burn-induced neutrophil chemotaxis defect. Altogether, this study identifies a newly described pathway of ceramide-mediated suppression of neutrophil chemotaxis after burn injury and introduces potential targets to mitigate this defect and reduce infection-related morbidity and mortality after burn.
Selenium increases hepatic DNA methylation and modulates one-carbon metabolism in the liver of mice
(2017)
The average intake of the essential trace element selenium (Se) is below the recommendation in most European countries, possibly causing sub-optimal expression of selenoproteins. It is still unclear how a suboptimal Se status may affect health. To mimic this situation, mice were fed one of three physiologically relevant amounts of Se. We focused on the liver, the organ most sensitive to changes in the Se supply indicated by hepatic glutathione peroxidase activity. In addition, liver is the main organ for synthesis of methyl groups and glutathione via one-carbon metabolism. Accordingly, the impact of Se on global DNA methylation, methylation capacity, and gene expression was assessed. We observed higher global DNA methylation indicated by LINE1 methylation, and an increase of the methylation potential as indicated by higher S-adenosylmethionine (SAM)/S-adenosylhomocysteine (SAH) ratio and by elevated mRNA expression of serine hydroxymethyltransferase in both or either of the Se groups. Furthermore, increasing the Se supply resulted in higher plasma concentrations of triglycerides. Hepatic expression of glycolytic and lipogenic genes revealed consistent Se dependent up-regulation of glucokinase. The sterol regulatory element-binding transcription factor 1 (Srebf1) was also up-regulated by Se. Both effects were confirmed in primary hepatocytes. In contrast to the overall Se-dependent increase of methylation capacity, the up-regulation of Srebf1 expression was paralleled by reduced local methylation of a specific CpG site within the Srebf1 gene. Thus, we provided evidence that Se-dependent effects on lipogenesis involve epigenetic mechanisms. (C) 2017 The Authors. Published by Elsevier Inc.
The visceral protein transthyretin (TTR) is frequently affected by oxidative post-translational protein modifications (PTPMs) in various diseases. Thus, better insight into structure-function relationships due to oxidative PTPMs of TTR should contribute to the understanding of pathophysiologic mechanisms. While the in vivo analysis of TTR in mammalian models is complex, time- and resource-consuming, transgenic Caenorhabditis elegans expressing hTTR provide an optimal model for the in vivo identification and characterization of drug-mediated oxidative PTPMs of hTTR by means of matrix assisted laser desorption/ionization – time of flight – mass spectrometry (MALDI-TOF-MS). Herein, we demonstrated that hTTR is expressed in all developmental stages of Caenorhabditis elegans, enabling the analysis of hTTR metabolism during the whole life-cycle. The suitability of the applied model was verified by exposing worms to D-penicillamine and menadione. Both drugs induced substantial changes in the oxidative PTPM pattern of hTTR. Additionally, for the first time a covalent binding of both drugs with hTTR was identified and verified by molecular modelling.
Mitochondria are critical for hypothalamic function and regulators of metabolism. Hypothalamic mitochondrial dysfunction with decreased mitochondrial chaperone expression is present in type 2 diabetes (T2D). Recently, we demonstrated that a dysregulated mitochondrial stress response (MSR) with reduced chaperone expression in the hypothalamus is an early event in obesity development due to insufficient insulin signaling. Although insulin activates this response and improves metabolism, the metabolic impact of one of its members, the mitochondrial chaperone heat shock protein 10 (Hsp10), is unknown. Thus, we hypothesized that a reduction of Hsp10 in hypothalamic neurons will impair mitochondrial function and impact brain insulin action. Therefore, we investigated the role of chaperone Hsp10 by introducing a lentiviral-mediated Hsp10 knockdown (KD) in the hypothalamic cell line CLU-183 and in the arcuate nucleus (ARC) of C57BL/6N male mice. We analyzed mitochondrial function and insulin signaling utilizing qPCR, Western blot, XF96 Analyzer, immunohistochemistry, and microscopy techniques. We show that Hsp10 expression is reduced in T2D mice brains and regulated by leptin in vitro. Hsp10 KD in hypothalamic cells induced mitochondrial dysfunction with altered fatty acid metabolism and increased mitochondria-specific oxidative stress resulting in neuronal insulin resistance. Consequently, the reduction of Hsp10 in the ARC of C57BL/6N mice caused hypothalamic insulin resistance with acute liver insulin resistance.