The Experts below are selected from a list of 4893 Experts worldwide ranked by ideXlab platform
Erich Gulbins - One of the best experts on this subject based on the ideXlab platform.
-
The Role of Acid Sphingomyelinase Inhibition in Repetitive Mild Traumatic Brain Injury.
The Journal of surgical research, 2020Co-Authors: Grace M. Niziolek, Michael J. Edwards, Erich Gulbins, Richard S. Hoehn, Peter L. Jernigan, Aaron P. Seitz, Amy T. Makley, Michael D. GoodmanAbstract:Abstract Background Chronic traumatic encephalopathy is a consequence of repetitive mild traumatic brain injury (rmTBI). These injuries can result in psychiatric disorders that are treated with amitriptyline. Amitriptyline improves neuronal regeneration in major depression via inhibition of Acid Sphingomyelinase. We hypothesized that Acid Sphingomyelinase inhibition would preserve neuronal regeneration and decrease depressive symptoms following rmTBI in a murine model. Methods A murine model of rmTBI was established using a weight-drop method. Mice were subjected to mTBI every other day for 7 d. Mice received amitriptyline injection 2 h prior to each mTBI. After the final mTBI, mice underwent behavioral studies or biochemical analysis. Hippocampi were analyzed for markers of neurogenesis and phosphorylated tau aggregation. Results Mice that underwent rmTBI showed increased hippocampal phosphorylated tau aggregation 1 mo following rmTBI as well as decreased neuronal regeneration by bromodeoxyuridine uptake and doublecortin immunohistochemistry. Mice with either genetic deficiency or pharmacologic inhibition of Acid Sphingomyelinase demonstrated improved neuronal regeneration and decreased phosphorylated tau aggregation compared to untreated rmTBI mice. Behavioral testing showed rmTBI mice spent significantly more time in the dark and waiting to initiate feeding compared to sham mice. These behaviors were partially prevented by the inhibition of Acid Sphingomyelinase. Conclusions We established a murine model of rmTBI that leads to tauopathy, depression, and impaired hippocampal neurogenesis. Inhibition of Acid Sphingomyelinase prevented the harmful neurologic and behavioral effects of rmTBI. These findings highlight an important opportunity to improve recovery or prevent neuropsychiatric decline in patients at risk for chronic traumatic encephalopathy.
-
Acid Sphingomyelinase Deficiency Ameliorates Farber Disease.
International Journal of Molecular Sciences, 2019Co-Authors: Nadine Beckmann, Katrin Anne Becker, Stephanie Kadow, Fabian Schumacher, Melanie Kramer, Claudine Kühn, Walter J. Schulz-schaeffer, Michael J. Edwards, Burkhard Kleuser, Erich GulbinsAbstract:Farber disease is a rare lysosomal storage disorder resulting from Acid ceramidase deficiency and subsequent ceramide accumulation. No treatments for Farber disease are clinically available, and affected patients have a severely shortened lifespan. We have recently reported a novel Acid ceramidase deficiency model that mirrors the human disease closely. Acid Sphingomyelinase is the enzyme that generates ceramide upstream of Acid ceramidase in the lysosomes. Using our Acid ceramidase deficiency model, we tested if Acid Sphingomyelinase could be a potential novel therapeutic target for the treatment of Farber disease. A number of functional Acid Sphingomyelinase inhibitors are clinically available and have been used for decades to treat major depression. Using these as a therapeutic for Farber disease, thus, has the potential to improve central nervous symptoms of the disease as well, something all other treatment options for Farber disease can’t achieve so far. As a proof-of-concept study, we first cross-bred Acid ceramidase deficient mice with Acid Sphingomyelinase deficient mice in order to prevent ceramide accumulation. Double-deficient mice had reduced ceramide accumulation, fewer disease manifestations, and prolonged survival. We next targeted Acid Sphingomyelinase pharmacologically, to test if these findings would translate to a setting with clinical applicability. Surprisingly, the treatment of Acid ceramidase deficient mice with the Acid Sphingomyelinase inhibitor amitriptyline was toxic to Acid ceramidase deficient mice and killed them within a few days of treatment. In conclusion, our study provides the first proof-of-concept that Acid Sphingomyelinase could be a potential new therapeutic target for Farber disease to reduce disease manifestations and prolong survival. However, we also identified previously unknown toxicity of the functional Acid Sphingomyelinase inhibitor amitriptyline in the context of Farber disease, strongly cautioning against the use of this substance class for Farber disease patients.
-
Pharmacological Inhibition of Acid Sphingomyelinase Ameliorates Experimental Autoimmune Encephalomyelitis.
Neuro-Signals, 2019Co-Authors: Silke Walter, Katrin Anne Becker, Erich Gulbins, Ramona Halmer, Neda Haghayegh Jahromi, Andrea Schottek, Claudia Blatti, Laura Davies, Laura Schnoeder, Thomas BertschAbstract:BACKGROUND/AIMS Multiple sclerosis (MS) is one of the most common autoimmune disorders of the central nervous system (CNS) and the leading cause of neurological disability among young adults in the Western world. We have previously shown that the Acid Sphingomyelinase plays an important role in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis. METHODS We induced adoptively transferred EAE in wildtype and Acid Sphingomyelinase-deficient mice. In addition, we immunized mice with MOGaa35-55 to induce active EAE and treated the mice with amitriptyline, a functional inhibitor of the Acid Sphingomyelinase. We investigated symptoms of EAE, blood-brain barrier integrity and neuroinflammation. RESULTS In the model of adoptively transferred EAE we demonstrate that expression of Acid Sphingomyelinase in the recipients rather than on transferred encephalitogenic T cells contributes to the clinical development of EAE symptoms. To test if pharmacological targeting of Acid Sphingomyelinase can be explored for the development of novel therapies for MS, we inhibited Acid Sphingomyelinase with amitriptyline in mice in which EAE was induced by active immunization. We demonstrate that pharmacological inhibition of Acid Sphingomyelinase using amitriptyline protects against the development of EAE and markedly attenuates the characteristic detrimental neuroinflammatory response. CONCLUSION The studies identify the Acid Sphingomyelinase as a novel therapeutic target for treating MS patients.
-
Acid Sphingomyelinase-Ceramide System in Bacterial Infections.
Cellular physiology and biochemistry : international journal of experimental cellular physiology biochemistry and pharmacology, 2019Co-Authors: Anni Wang, Erich Gulbins, Heike Grassmé, Zhigang ZhaoAbstract:Acid Sphingomyelinase hydrolyzes sphingomyelin to ceramide and phosphorylcholine. Ceramide molecules spontaneously interact with each other and generate ceramide-enriched membrane domains. These ceramide-enriched domains further fuse, forming large ceramideenriched platforms that participate in the organization of receptors and in the amplification of signaling molecules. Recent studies have suggested several bacteria and bacterial toxins that stimulate the activation and the translocation of Acid Sphingomyelinase, which leads to the release of ceramide. The Acid Sphingomyelinase/ceramide system also regulates the internalization of bacteria into the host cell, the subsequent cytokine release, inflammatory response, and initiation of host cell apoptosis. In addition, ceramide has been implicated in the fusion of phagosomes and lysosomes upon bacterial infection. Thus, this system modulates the reorganization of cell membrane receptors and intracellular signaling molecules during bacteria-host interactions. The Acid Sphingomyelinase and ceramide system may thus serve as a novel therapeutic target for treating infections.
-
Blockade of Experimental Multiple Sclerosis by Inhibition of the Acid Sphingomyelinase/Ceramide System.
Neuro-Signals, 2017Co-Authors: Katrin Anne Becker, Erich Gulbins, Brian Henry, Ramona Halmer, Laura Davies, Klaus Fassbender, Regan Ziobro-henry, Yann Decker, Yang Liu, Silke WalterAbstract:BACKGROUND Multiple sclerosis (MS) is a severe and common autoimmune disorder of the central nervous system. Despite the availability of several novel treatment options, the disease is still poorly controlled, since the pathophysiological mechanisms are not fully understood. METHODS We tested the role of the Acid Sphingomyelinase/ceramide system in a model of MS, i.e. experimental autoimmune encephalomyelitis (EAE). Mice were immunized with myelin-oligodendrocyte glycoprotein and the development of the disease was analyzed by histology, immunological tests and clinical assessment in wildtype and Acid Sphingomyelinase (Asm)-deficient mice. RESULTS Genetic deficiency of Acid Sphingomyelinase (Asm) protected against clinical symptoms in EAE and markedly attenuated the characteristic detrimental neuroinflammatory response. T lymphocyte adhesion, integrity of tight junctions, blood-brain barrier disruption and subsequent intracerebral infiltration of inflammatory cells were blocked in Asm-deficient mice after immunization. This resulted in an almost complete block of the development of disease symptoms in these mice, while wildtype mice showed severe neurological symptoms typical for EAE. CONCLUSION Activation of the Asm/ceramide system is a central step for the development of EAE. Our findings may serve to identify novel therapeutic strategies for MS patients.
Konrad Sandhoff - One of the best experts on this subject based on the ideXlab platform.
-
functional characterization of the postulated intramolecular sphingolipid activator protein domain of human Acid Sphingomyelinase
Biological Chemistry, 2004Co-Authors: Melanie Kolzer, O. Bartelsen, Silvia Locatelli Hoops, K. Ferlinz, Florian Lang, Konrad SandhoffAbstract:: Degradation of membrane-bound sphingomyelin to phosphorylcholine and ceramide is catalyzed by the water-soluble lysosomal Acid Sphingomyelinase (A-SMase). The presence of sphingolipid activator proteins (Saps: saposins A-D; GM2 activator) is not essential to mediate this reaction at the water-lipid interface in vivo . A hypothesis based on amino Acid sequence alignments suggests that the enzyme possesses an N-terminal saposin-homologous domain, which may facilitate the enzymatic reaction at the interface. We mutated one homologous and three conserved amino Acid residues of this domain and studied the activity of the variant enzymes using different sphingomyelin degradation assays. A variant with an exchange of a conserved amino Acid residue, Pro153Ala, still exhibited enzyme activity of approximately 52% of normal in a detergent-containing micellar assay, but only 13% of normal in a detergent-free liposomal assay system, which suggests that the Sap-homologous domain fulfills membrane-disturbing functions. Addition of saposin C to the liposomal assay mixtures increased the Pro153Ala variant Sphingomyelinase activity to 46% of normal, indicating that the variant saposin-like domain can be substituted by the presence of the sphingolipid activator protein. On the other hand, the addition of saposin C did not result in complete restoration of the variant activity. Thus, the Sap-like domain may also have another role, e.g., to stabilize the fold of Acid Sphingomyelinase, which cannot be compensated by the presence of saposin C or a detergent. Such an essential second function of the saposin-like domain as an integral part of Acid Sphingomyelinase is confirmed by our observation that the Lys118Glu, Cys120Ser and Cys131Ser variants were almost completely devoid of activity in the detergent-containing micellar assay system as well as in the liposomal assay system in the presence of saposin C.
-
Purification and Characterization of Recombinant, Human Acid Ceramidase CATALYTIC REACTIONS AND INTERACTIONS WITH Acid Sphingomyelinase
The Journal of biological chemistry, 2003Co-Authors: Nozomu Okino, Konrad Sandhoff, Arie Dagan, Shimon Gatt, Heike Schulze, Rajwinder Dhami, Edward H. SchuchmanAbstract:Abstract Human Acid ceramidase was overexpressed in Chinese hamster ovary cells by amplification of the transfected, full-length cDNA. The majority of the overexpressed enzyme was secreted into the culture media and purified to apparent homogeneity. The purified protein contained the same 13-(α) and 40 (β)–kDa subunits as human Acid ceramidase from natural sources, had an Acidic pH optimum (4.5), and followed normal Michaelis-Menten kinetics using 14C- and BODIPY-labeled C12-ceramide as substrates. Deglycosylation studies showed that the recombinant enzyme contained mostly “high mannose” type oligosaccharides and that two distinct β-subunits were present. Amino Acid sequencing of these subunit polypeptides revealed a single N terminus, suggesting that the ∼2–4-kDa molecular mass difference was likely due to C-terminal processing. The purified enzyme also catalyzed ceramide synthesis in vitro using 14C-labeled C12 fatty Acid and sphingosine as substrates. Surprisingly, we found that media from the overexpressing hamster cells had increased Acid Sphingomyelinase activity and that this activity could be co-precipitated with Acid ceramidase using anti-ceramidase antibodies. Overexpression of Acid ceramidase in normal human skin fibroblasts also led to enhanced Acid Sphingomyelinase secretion, but this was not observed in Niemann-Pick disease cells. RNA studies showed that this increased activity was not due to overexpression of the endogenous Acid Sphingomyelinase gene. Uptake studies using mouse macrophages revealed rapid internalization of the Acid ceramidase activity from the hamster cell media but not Acid Sphingomyelinase. These studies provide new insights into Acid ceramidase and the related lipid hydrolase, Acid Sphingomyelinase.
-
Phosphatidylinositol-3,5-Bisphosphate is a potent and selective inhibitor of Acid Sphingomyelinase.
Biological chemistry, 2003Co-Authors: Melanie Kolzer, Heike Schulze, Christoph Arenz, Klaus Ferlinz, Norbert Werth, Ralf Klingenstein, Konrad SandhoffAbstract:Acid Sphingomyelinase (A-SMase, EC 3.1.4.12) catalyzes the lysosomal degradation of sphingomyelin to phosphorylcholine and ceramide. Inherited deficiencies of Acid Sphingomyelinase activity result in various clinical forms of Niemann-Pick disease, which are characterised by massive lysosomal accumulation of sphingomyelin. Sphingomyelin hydrolysis by both, Acid Sphingomyelinase and membrane-associated neutral Sphingomyelinase, plays also an important role in cellular signaling systems regulating proliferation, apoptosis and differentiation. Here, we present a potent and selective novel inhibitor of A-SMase, L-alpha-phosphatidyl-D-myo-inositol-3,5-bisphosphate (PtdIns3,5P2), a naturally occurring substance detected in mammalian, plant and yeast cells. The inhibition constant Ki for the new A-SMase inhibitor PtdIns3,5P2 is 0.53 microM as determined in a micellar assay system with radiolabeled sphingomyelin as substrate and recombinant human A-SMase purified from insect cells. Even at concentrations of up to 50 microM, PtdIns3,5P2 neither decreased plasma membrane-associated, magnesium-dependent neutral Sphingomyelinase activity, nor was it an inhibitor of the lysosomal hydrolases beta-hexosaminidase A and Acid ceramidase. Other phosphoinositides tested had no or a much weaker effect on Acid Sphingomyelinase. Different inositol-bisphosphates were studied to elucidate structure-activity relationships for A-SMase inhibition. Our investigations provide an insight into the structural features required for selective, efficient inhibition of Acid Sphingomyelinase and may also be used as starting point for the development of new potent A-SMase inhibitors optimised for diverse applications.
-
Stimulation of Acid Sphingomyelinase activity by lysosomal lipids and sphingolipid activator proteins
Biological Chemistry, 2001Co-Authors: Thomas Linke, S. Lansmann, H. Moczall, O. Bartelsen, Guenter Wilkening, John Weisgerber, Konrad SandhoffAbstract:Acid Sphingomyelinase is a water-soluble, lysosomal glycoprotein that catalyzes the degradation of mem- brane-bound sphingomyelin into phosphorylcholine and ceramide. Sphingomyelin itself is an important component of the extracellular leaflet of various cellu- lar membranes. The aim of the present investigation was to study sphingomyelin hydrolysis as a mem- brane-bound process. We analyzed the degradation of sphingomyelin by recombinant, highly purified Acid Sphingomyelinase in a detergent-free, liposomal as- say system. In order to mimic the in vivo intralysoso- mal conditions as closely as possible a number of negatively charged, lysosomally occuring lipids in- cluding bis(monoacylglycero)phosphate and phos- phatidylinositol were incorporated into substrate- carrying liposomes. Dolichol and its phosphate ester dolicholphosphate were also included in this study. Bis(monoacylglycero)phosphate and phosphatidyl- inositol were both effective stimulators of sphin- gomyelin hydrolysis. Dolichol and dolicholphosphate also significantly increased sphingomyelin hydrolysis. The influence of membrane curvature was investigat- ed by incorporating the substrate into small (SUVs) and large unilamellar vesicles (LUVs) with varying mean diameter. Degradation rates were substantially higher in SUVs than in LUVs. Surface plasmon reso- nance experiments demonstrated that Acid sphin- gomyelinase binds strongly to lipid bilayers. This in- teraction is significantly enhanced by anionic lipids such as bis(monoacylglycero)phosphate. Under de- tergent-free conditions only the sphingolipid activator protein SAP-C had a pronounced influence on sphin- gomyelin degradation in both neutral and negatively charged liposomes, catalyzed by highly purified Acid Sphingomyelinase, while SAP-A, -B and -D had no no- ticeable effect on sphingomyelin degradation.
Katrin Anne Becker - One of the best experts on this subject based on the ideXlab platform.
-
Acid Sphingomyelinase Deficiency Ameliorates Farber Disease.
International Journal of Molecular Sciences, 2019Co-Authors: Nadine Beckmann, Katrin Anne Becker, Stephanie Kadow, Fabian Schumacher, Melanie Kramer, Claudine Kühn, Walter J. Schulz-schaeffer, Michael J. Edwards, Burkhard Kleuser, Erich GulbinsAbstract:Farber disease is a rare lysosomal storage disorder resulting from Acid ceramidase deficiency and subsequent ceramide accumulation. No treatments for Farber disease are clinically available, and affected patients have a severely shortened lifespan. We have recently reported a novel Acid ceramidase deficiency model that mirrors the human disease closely. Acid Sphingomyelinase is the enzyme that generates ceramide upstream of Acid ceramidase in the lysosomes. Using our Acid ceramidase deficiency model, we tested if Acid Sphingomyelinase could be a potential novel therapeutic target for the treatment of Farber disease. A number of functional Acid Sphingomyelinase inhibitors are clinically available and have been used for decades to treat major depression. Using these as a therapeutic for Farber disease, thus, has the potential to improve central nervous symptoms of the disease as well, something all other treatment options for Farber disease can’t achieve so far. As a proof-of-concept study, we first cross-bred Acid ceramidase deficient mice with Acid Sphingomyelinase deficient mice in order to prevent ceramide accumulation. Double-deficient mice had reduced ceramide accumulation, fewer disease manifestations, and prolonged survival. We next targeted Acid Sphingomyelinase pharmacologically, to test if these findings would translate to a setting with clinical applicability. Surprisingly, the treatment of Acid ceramidase deficient mice with the Acid Sphingomyelinase inhibitor amitriptyline was toxic to Acid ceramidase deficient mice and killed them within a few days of treatment. In conclusion, our study provides the first proof-of-concept that Acid Sphingomyelinase could be a potential new therapeutic target for Farber disease to reduce disease manifestations and prolong survival. However, we also identified previously unknown toxicity of the functional Acid Sphingomyelinase inhibitor amitriptyline in the context of Farber disease, strongly cautioning against the use of this substance class for Farber disease patients.
-
Pharmacological Inhibition of Acid Sphingomyelinase Ameliorates Experimental Autoimmune Encephalomyelitis.
Neuro-Signals, 2019Co-Authors: Silke Walter, Katrin Anne Becker, Erich Gulbins, Ramona Halmer, Neda Haghayegh Jahromi, Andrea Schottek, Claudia Blatti, Laura Davies, Laura Schnoeder, Thomas BertschAbstract:BACKGROUND/AIMS Multiple sclerosis (MS) is one of the most common autoimmune disorders of the central nervous system (CNS) and the leading cause of neurological disability among young adults in the Western world. We have previously shown that the Acid Sphingomyelinase plays an important role in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis. METHODS We induced adoptively transferred EAE in wildtype and Acid Sphingomyelinase-deficient mice. In addition, we immunized mice with MOGaa35-55 to induce active EAE and treated the mice with amitriptyline, a functional inhibitor of the Acid Sphingomyelinase. We investigated symptoms of EAE, blood-brain barrier integrity and neuroinflammation. RESULTS In the model of adoptively transferred EAE we demonstrate that expression of Acid Sphingomyelinase in the recipients rather than on transferred encephalitogenic T cells contributes to the clinical development of EAE symptoms. To test if pharmacological targeting of Acid Sphingomyelinase can be explored for the development of novel therapies for MS, we inhibited Acid Sphingomyelinase with amitriptyline in mice in which EAE was induced by active immunization. We demonstrate that pharmacological inhibition of Acid Sphingomyelinase using amitriptyline protects against the development of EAE and markedly attenuates the characteristic detrimental neuroinflammatory response. CONCLUSION The studies identify the Acid Sphingomyelinase as a novel therapeutic target for treating MS patients.
-
Blockade of Experimental Multiple Sclerosis by Inhibition of the Acid Sphingomyelinase/Ceramide System.
Neuro-Signals, 2017Co-Authors: Katrin Anne Becker, Erich Gulbins, Brian Henry, Ramona Halmer, Laura Davies, Klaus Fassbender, Regan Ziobro-henry, Yann Decker, Yang Liu, Silke WalterAbstract:BACKGROUND Multiple sclerosis (MS) is a severe and common autoimmune disorder of the central nervous system. Despite the availability of several novel treatment options, the disease is still poorly controlled, since the pathophysiological mechanisms are not fully understood. METHODS We tested the role of the Acid Sphingomyelinase/ceramide system in a model of MS, i.e. experimental autoimmune encephalomyelitis (EAE). Mice were immunized with myelin-oligodendrocyte glycoprotein and the development of the disease was analyzed by histology, immunological tests and clinical assessment in wildtype and Acid Sphingomyelinase (Asm)-deficient mice. RESULTS Genetic deficiency of Acid Sphingomyelinase (Asm) protected against clinical symptoms in EAE and markedly attenuated the characteristic detrimental neuroinflammatory response. T lymphocyte adhesion, integrity of tight junctions, blood-brain barrier disruption and subsequent intracerebral infiltration of inflammatory cells were blocked in Asm-deficient mice after immunization. This resulted in an almost complete block of the development of disease symptoms in these mice, while wildtype mice showed severe neurological symptoms typical for EAE. CONCLUSION Activation of the Asm/ceramide system is a central step for the development of EAE. Our findings may serve to identify novel therapeutic strategies for MS patients.
-
Staphylococcus aureus Alpha-Toxin Disrupts Endothelial-Cell Tight Junctions via Acid Sphingomyelinase and Ceramide.
Infection and immunity, 2017Co-Authors: Katrin Anne Becker, Simone Keitsch, Barbara Wilker, Matthias Soddemann, Björn Fahsel, Hannes Kemper, Joelina Mayeres, Carolin Sehl, Marcus KohnenAbstract:ABSTRACT Staphylococcus aureus (S. aureus) infections are among the most common and severe infections, garnering notoriety in an era of increasing resistance to antibiotics. It is therefore important to define molecular mechanisms by which this pathogen attacks host cells. Here, we demonstrate that alpha-toxin, one of the major toxins of S. aureus, induces activation of Acid Sphingomyelinase and concomitant release of ceramide in endothelial cells treated with the toxin. Activation of Acid Sphingomyelinase by alpha-toxin is mediated via ADAM10. Infection experiments employing alpha-toxin-deficient S. aureus and the corresponding wild-type strain reveal that activation of Acid Sphingomyelinase in endothelial cells requires alpha-toxin expression by the pathogen. Activation of Acid Sphingomyelinase is linked to degradation of tight junctions in endothelial cells in vitro, which is blocked by pharmacological inhibition of Acid Sphingomyelinase. Most importantly, alpha-toxin induces severe degradation of tight junctions in the lung and causes lung edema in vivo, which is prevented by genetic deficiency of Acid Sphingomyelinase. These data indicate a novel and important role of the Acid Sphingomyelinase/ceramide system for the endothelial response to toxins and provide a molecular link between alpha-toxin and the degradation of tight junctions. The data also suggest that inhibition of Acid Sphingomyelinase may provide a novel treatment option to prevent lung edema caused by S. aureus alpha-toxin.
-
Staphylococcus aureus α-Toxin Induces Inflammatory Cytokines via Lysosomal Acid Sphingomyelinase and Ceramides.
Cellular physiology and biochemistry : international journal of experimental cellular physiology biochemistry and pharmacology, 2017Co-Authors: Erich Gulbins, Michael J. Edwards, Charles C. Caldwell, Martin Fraunholz, Katrin Anne BeckerAbstract:Background/Aims: Staphylococcus aureus ( S. aureus ) infections are a major clinical problem and range from mild skin and soft-tissue infections to severe and even lethal infections such as pneumonia, endocarditis, sepsis, osteomyelitis, and toxic shock syndrome. Toxins that are released from S. aureus mediate many of these effects. Here, we aimed to identify molecular mechanisms how α-toxin, a major S. aureus toxin, induces inflammation. Methods: Macrophages were isolated from the bone marrow of wildtype and Acid Sphingomyelinase-deficient mice, stimulated with S. aureus α-toxin and activation of the Acid Sphingomyelinase was quantified. The subcellular formation of ceramides was determined by confocal microscopy. Release of cathepsins from lysosomes, activation of inflammasome proteins and formation of Interleukin-1β (IL-1β) and Tumor Necrosis Factor-α (TNF-α) were analyzed by western blotting, confocal microscopy and ELISA. Results: We demonstrate that S. aureus α-toxin activates the Acid Sphingomyelinase in ex vivo macrophages and triggers a release of ceramides. Ceramides induced by S. aureus α-toxin localize to lysosomes and mediate a release of cathepsin B and D from lysosomes into the cytoplasm. Cytosolic cathepsin B forms a complex with Nlrc4. Treatment of macrophages with α-toxin induces the formation of IL-1β and TNF-α. These events are reduced or abrogated, respectively, in cells lacking the Acid Sphingomyelinase and upon treatment of macrophages with amitriptyline, a functional inhibitor of Acid Sphingomyelinase. Pharmacological inhibition of cathepsin B prevented activation of the inflammasome measured as release of IL-1β, while the formation of TNF-α was independent of cathepsin B. Conclusion: We demonstrate a novel mechanism how bacterial toxins activate the inflammasome and mediate the formation and release of cytokines: S. aureus α-toxin triggers an activation of the Acid Sphingomyelinase and a release of ceramides resulting in the release of lysosomal cathepsin B and formation of pro-inflammatory cytokines.
Michael J. Edwards - One of the best experts on this subject based on the ideXlab platform.
-
The Role of Acid Sphingomyelinase Inhibition in Repetitive Mild Traumatic Brain Injury.
The Journal of surgical research, 2020Co-Authors: Grace M. Niziolek, Michael J. Edwards, Erich Gulbins, Richard S. Hoehn, Peter L. Jernigan, Aaron P. Seitz, Amy T. Makley, Michael D. GoodmanAbstract:Abstract Background Chronic traumatic encephalopathy is a consequence of repetitive mild traumatic brain injury (rmTBI). These injuries can result in psychiatric disorders that are treated with amitriptyline. Amitriptyline improves neuronal regeneration in major depression via inhibition of Acid Sphingomyelinase. We hypothesized that Acid Sphingomyelinase inhibition would preserve neuronal regeneration and decrease depressive symptoms following rmTBI in a murine model. Methods A murine model of rmTBI was established using a weight-drop method. Mice were subjected to mTBI every other day for 7 d. Mice received amitriptyline injection 2 h prior to each mTBI. After the final mTBI, mice underwent behavioral studies or biochemical analysis. Hippocampi were analyzed for markers of neurogenesis and phosphorylated tau aggregation. Results Mice that underwent rmTBI showed increased hippocampal phosphorylated tau aggregation 1 mo following rmTBI as well as decreased neuronal regeneration by bromodeoxyuridine uptake and doublecortin immunohistochemistry. Mice with either genetic deficiency or pharmacologic inhibition of Acid Sphingomyelinase demonstrated improved neuronal regeneration and decreased phosphorylated tau aggregation compared to untreated rmTBI mice. Behavioral testing showed rmTBI mice spent significantly more time in the dark and waiting to initiate feeding compared to sham mice. These behaviors were partially prevented by the inhibition of Acid Sphingomyelinase. Conclusions We established a murine model of rmTBI that leads to tauopathy, depression, and impaired hippocampal neurogenesis. Inhibition of Acid Sphingomyelinase prevented the harmful neurologic and behavioral effects of rmTBI. These findings highlight an important opportunity to improve recovery or prevent neuropsychiatric decline in patients at risk for chronic traumatic encephalopathy.
-
Pharmacological inhibition of Acid Sphingomyelinase prevents uptake of SARS-CoV-2 by epithelial cells.
Cell reports. Medicine, 2020Co-Authors: Alexander Carpinteiro, Michael J. Edwards, Markus Hoffmann, Georg Kochs, Barbara Gripp, Sebastian Weigang, Constantin Adams, Elisa Carpinteiro, Anne Gulbins, Simone KeitschAbstract:The Acid Sphingomyelinase/ceramide system plays an important role in bacterial and viral infections. Here, we report that either pharmacological inhibition of Acid Sphingomyelinase with amitriptyline, imipramine, fluoxetine, sertraline, escitalopram, or maprotiline or genetic downregulation of the enzyme prevents infection of cultured cells or freshy isolated human nasal epithelial cells with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or vesicular stomatitis virus (VSV) pseudoviral particles (pp-VSV) presenting SARS-CoV-2 spike protein (pp-VSV-SARS-CoV-2 spike), a bona fide system mimicking SARS-CoV-2 infection. Infection activates Acid Sphingomyelinase and triggers a release of ceramide on the cell surface. Neutralization or consumption of surface ceramide reduces infection with pp-VSV-SARS-CoV-2 spike. Treating volunteers with a low dose of amitriptyline prevents infection of freshly isolated nasal epithelial cells with pp-VSV-SARS-CoV-2 spike. The data justify clinical studies investigating whether amitriptyline, a safe drug used clinically for almost 60 years, or other antidepressants that functionally block Acid Sphingomyelinase prevent SARS-CoV-2 infection.
-
Inhibition of Acid Sphingomyelinase Blocks Infection with SARS-CoV-2
SSRN Electronic Journal, 2020Co-Authors: Alexander Carpinteiro, Michael J. Edwards, Markus Hoffmann, Georg Kochs, Barbara Gripp, Sebastian Weigang, Constantin Adams, Elisa Carpinteiro, Anne Gulbins, Simone KeitschAbstract:We have previously shown that the Acid Sphingomyelinase/ceramide system plays an important role in bacterial and viral infections. Pharmacological inhibition of Acid Sphingomyelinase with amitriptyline, imipramine, fluoxetine, sertraline, escitalopram or maprotiline or genetic down-regulation of the enzyme prevents infection with authentic SARS-CoV-2 or pseudoviral particles expressing pp-VSV-SARS-CoV-2 spike that served as a bona fide system mimicking SARS-CoV-2 infection. Mechanistically, Acid Sphingomyelinase mediates the formation of ceramide-enriched membrane platforms that serve the infection with pp-VSV-SARS-CoV-2 spike. Neutralization or consumption of surface ceramide reduces infection with pp-VSV-SARS-CoV-2 spike. Treatment of volunteers with a low dose of amitriptyline prevents infection of freshly isolated nasal epithelial cells with pp-VSV-SARS-CoV-2 spike, indicating that amitriptyline can be repurposed to prevent SARS-CoV-2 infection. Our data suggest the use of amitriptyline, a safe drug clinically used for almost 60 years, other antidepressants blocking the Acid Sphingomyelinase, anti-ceramide antibodies and neutral ceramidase for prophylaxis and treatment of coronavirus disease-19. Funding: The study was supported by DFG grant Gu-335-35/1 and BMBF, RAPID Consortium, grant 01KI1723D to SP. Conflict of Interest: The authors declare no competing financial interests. Ethical Approval: The experiments were approved by the local ethics committee under the number 20-9348-BO.
-
Acid Sphingomyelinase Deficiency Ameliorates Farber Disease.
International Journal of Molecular Sciences, 2019Co-Authors: Nadine Beckmann, Katrin Anne Becker, Stephanie Kadow, Fabian Schumacher, Melanie Kramer, Claudine Kühn, Walter J. Schulz-schaeffer, Michael J. Edwards, Burkhard Kleuser, Erich GulbinsAbstract:Farber disease is a rare lysosomal storage disorder resulting from Acid ceramidase deficiency and subsequent ceramide accumulation. No treatments for Farber disease are clinically available, and affected patients have a severely shortened lifespan. We have recently reported a novel Acid ceramidase deficiency model that mirrors the human disease closely. Acid Sphingomyelinase is the enzyme that generates ceramide upstream of Acid ceramidase in the lysosomes. Using our Acid ceramidase deficiency model, we tested if Acid Sphingomyelinase could be a potential novel therapeutic target for the treatment of Farber disease. A number of functional Acid Sphingomyelinase inhibitors are clinically available and have been used for decades to treat major depression. Using these as a therapeutic for Farber disease, thus, has the potential to improve central nervous symptoms of the disease as well, something all other treatment options for Farber disease can’t achieve so far. As a proof-of-concept study, we first cross-bred Acid ceramidase deficient mice with Acid Sphingomyelinase deficient mice in order to prevent ceramide accumulation. Double-deficient mice had reduced ceramide accumulation, fewer disease manifestations, and prolonged survival. We next targeted Acid Sphingomyelinase pharmacologically, to test if these findings would translate to a setting with clinical applicability. Surprisingly, the treatment of Acid ceramidase deficient mice with the Acid Sphingomyelinase inhibitor amitriptyline was toxic to Acid ceramidase deficient mice and killed them within a few days of treatment. In conclusion, our study provides the first proof-of-concept that Acid Sphingomyelinase could be a potential new therapeutic target for Farber disease to reduce disease manifestations and prolong survival. However, we also identified previously unknown toxicity of the functional Acid Sphingomyelinase inhibitor amitriptyline in the context of Farber disease, strongly cautioning against the use of this substance class for Farber disease patients.
-
Staphylococcus aureus α-Toxin Induces Inflammatory Cytokines via Lysosomal Acid Sphingomyelinase and Ceramides.
Cellular physiology and biochemistry : international journal of experimental cellular physiology biochemistry and pharmacology, 2017Co-Authors: Erich Gulbins, Michael J. Edwards, Charles C. Caldwell, Martin Fraunholz, Katrin Anne BeckerAbstract:Background/Aims: Staphylococcus aureus ( S. aureus ) infections are a major clinical problem and range from mild skin and soft-tissue infections to severe and even lethal infections such as pneumonia, endocarditis, sepsis, osteomyelitis, and toxic shock syndrome. Toxins that are released from S. aureus mediate many of these effects. Here, we aimed to identify molecular mechanisms how α-toxin, a major S. aureus toxin, induces inflammation. Methods: Macrophages were isolated from the bone marrow of wildtype and Acid Sphingomyelinase-deficient mice, stimulated with S. aureus α-toxin and activation of the Acid Sphingomyelinase was quantified. The subcellular formation of ceramides was determined by confocal microscopy. Release of cathepsins from lysosomes, activation of inflammasome proteins and formation of Interleukin-1β (IL-1β) and Tumor Necrosis Factor-α (TNF-α) were analyzed by western blotting, confocal microscopy and ELISA. Results: We demonstrate that S. aureus α-toxin activates the Acid Sphingomyelinase in ex vivo macrophages and triggers a release of ceramides. Ceramides induced by S. aureus α-toxin localize to lysosomes and mediate a release of cathepsin B and D from lysosomes into the cytoplasm. Cytosolic cathepsin B forms a complex with Nlrc4. Treatment of macrophages with α-toxin induces the formation of IL-1β and TNF-α. These events are reduced or abrogated, respectively, in cells lacking the Acid Sphingomyelinase and upon treatment of macrophages with amitriptyline, a functional inhibitor of Acid Sphingomyelinase. Pharmacological inhibition of cathepsin B prevented activation of the inflammasome measured as release of IL-1β, while the formation of TNF-α was independent of cathepsin B. Conclusion: We demonstrate a novel mechanism how bacterial toxins activate the inflammasome and mediate the formation and release of cytokines: S. aureus α-toxin triggers an activation of the Acid Sphingomyelinase and a release of ceramides resulting in the release of lysosomal cathepsin B and formation of pro-inflammatory cytokines.
Christoph Arenz - One of the best experts on this subject based on the ideXlab platform.
-
A photocaged inhibitor of Acid Sphingomyelinase
Chemical communications (Cambridge England), 2020Co-Authors: Kevin Prause, Fabian Schumacher, Burkhard Kleuser, Gita Naseri, Christian Kappe, Christoph ArenzAbstract:Acid Sphingomyelinase (ASM) is a potential drug target and involved in rapid lipid signalling events. However, there are no tools available to adequately study such processes. Based on a non cell-permeable PtdIns(3,5)P2 inhibitor of ASM, we developed a compound with o-nitrobenzyl photocages and butyryl esters to transiently mask hydroxyl groups. This resulted in a potent light-inducible photocaged ASM inhibitor (PCAI). The first example of a time-resolved inhibition of ASM was shown in intact living cells.
-
A Novel Visible Range FRET Probe for Monitoring Acid Sphingomyelinase Activity in Living Cells.
Chemistry (Weinheim an der Bergstrasse Germany), 2020Co-Authors: Christian Kappe, Alexander Carpinteiro, Zainelabdeen H. Mohamed, Eyad Naser, Christoph ArenzAbstract:Activity of Acid Sphingomyelinase has been implicated in a number of diseases like acute lung injury, sepsis or metastasis of melanoma cells. Here, we present a Sphingomyelinase FRET probe based on FAM/BODIPY dyes for real-time monitoring of Acid Sphingomyelinase. The probe gives rise to a tremendous increase in fluorescence of the fluorescein FRET donor upon cleavage and we show that this is, to a significant part, due to cleavage-associated phase transition, suggesting a more systematic consideration of such effects for future probe development. The probe allows for the first time to monitor relative Sphingomyelinase activities of intact living cells by flow cytometry.
-
Acid Sphingomyelinase mediates murine acute lung injury following transfusion of aged platelets.
American journal of physiology. Lung cellular and molecular physiology, 2017Co-Authors: Mark J Mcvey, Burkhard Kleuser, Christoph Arenz, Lukasz Japtok, Michael Kim, Arata Tabuchi, Victoria Srbely, Ori Rotstein, John W Semple, Wolfgang M KueblerAbstract: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.
-
Small molecule inhibitors of Acid Sphingomyelinase.
Cellular physiology and biochemistry : international journal of experimental cellular physiology biochemistry and pharmacology, 2010Co-Authors: Christoph ArenzAbstract:Despite of the importance of the Acid Sphingomyelinase for sphingomyelin homeostasis and sphingolipid signalling, potent and selective inhibitors for this enzyme are rare. An increasing set of data on the inhibition of Acid Sphingomyelinase in different disease models using indirect inhibitors has been generated and strongly implies Acid Sphingomyelinase as an emerging drug target. Very recently, some new and promising inhibitors from different substance classes have been developed. In this review, previous and current developments in the field are summarized.
-
Development of carbohydrate-derived inhibitors of Acid Sphingomyelinase.
Bioorganic & medicinal chemistry, 2009Co-Authors: Anke G. Roth, Susanne Redmer, Christoph ArenzAbstract:The Acid Sphingomyelinase is an emerging drug target, especially for inflammatory lung diseases. Presently, there are no directly-acting potent inhibitors available for cell-based studies. The potent inhibitor phosphatidylinositol-3,5-bisphosphate (PtdIns3,5P2) is not only unsuited for cell culture studies, but also does not provide hints for further structural improvements. In the SAR study described here, we replaced the inositolphosphate moiety by a carbohydrate derivative and the phosphatidic Acid residue by an alkylsulfone ester. The resulting compound is more active than its parent compound and offers new means for further structural modification.