@misc{NojimaKonishiFreemanetal.2016, author = {Nojima, Hiroyuki and Konishi, Takanori and Freeman, Christopher M. and Schuster, Rebecca M. and Japtok, Lukasz and Kleuser, Burkhard and Edwards, Michael J. and Gulbins, Erich and Lentsch, Alex B.}, title = {Chemokine receptors, CXCR1 and CXCR2, differentially regulate exosome release in hepatocytes}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {538}, issn = {1866-8372}, doi = {10.25932/publishup-41088}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-410885}, pages = {15}, year = {2016}, abstract = {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.}, language = {en} } @article{NojimaKonishiFreemanetal.2016, author = {Nojima, Hiroyuki and Konishi, Takanori and Freeman, Christopher M. and Schuster, Rebecca M. and Japtok, Lukasz and Kleuser, Burkhard and Edwards, Michael J. and Gulbins, Erich and Lentsch, Alex B.}, title = {Chemokine Receptors, CXCR1 and CXCR2, Differentially Regulate Exosome Release in Hepatocytes}, series = {PLoS one}, volume = {11}, journal = {PLoS one}, publisher = {PLoS}, address = {San Fransisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0161443}, pages = {6900 -- +}, year = {2016}, abstract = {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.}, language = {en} } @misc{NojimaKonishiJaptoketal.2016, author = {Nojima, Hiroyuki and Konishi, Takanori and Japtok, Lukasz and Kleuser, Burkhard and Edwards, Michael J. and Gulbins, Erich and Lentsch, Alex B.}, title = {Chemokine receptors, CXCR1 and CXCR2, differentially regulate exosome release in hepatocytes}, series = {Hepatology : official journal of the American Association for the Study of Liver Diseases}, volume = {64}, journal = {Hepatology : official journal of the American Association for the Study of Liver Diseases}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0270-9139}, pages = {165A -- 165A}, year = {2016}, language = {en} } @misc{ReichelRheinHofmannetal.2018, author = {Reichel, Martin and Rhein, Cosima and Hofmann, Lena M. and Monti, Juliana and Japtok, Lukasz and Langgartner, Dominik and F{\"u}chsl, Andrea M. and Kleuser, Burkhard and Gulbins, Erich and Hellerbrand, Claus and Reber, Stefan O. and Kornhuber, Johannes}, title = {Chronic psychosocial stress in mice is associated with increased acid sphingomyelinase activity in liver and serum and with hepatic C16:0-ceramide accumulation}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1120}, issn = {1866-8372}, doi = {10.25932/publishup-44624}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-446241}, pages = {10}, year = {2018}, abstract = {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.}, language = {en} } @article{ReichelRheinHofmannetal.2018, author = {Reichel, Martin and Rhein, Cosima and Hofmann, Lena M. and Monti, Juliana and Japtok, Lukasz and Langgartner, Dominik and F{\"u}chsl, Andrea M. and Kleuser, Burkhard and Gulbins, Erich and Hellerbrand, Claus and Reber, Stefan O. and Kornhuber, Johannes}, title = {Chronic Psychosocial Stress in Mice Is Associated With Increased Acid Sphingomyelinase Activity in Liver and Serum and With Hepatic C16:0-Ceramide Accumulation}, series = {Frontiers in Psychiatry}, volume = {9}, journal = {Frontiers in Psychiatry}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-0640}, doi = {10.3389/fpsyt.2018.00496}, pages = {8}, year = {2018}, abstract = {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.}, language = {en} } @article{HenryNeillBeckeretal.2015, author = {Henry, Brian D. and Neill, Daniel R. and Becker, Katrin Anne and Gore, Suzanna and Bricio-Moreno, Laura and Ziobro, Regan and Edwards, Michael J. and Muehlemann, Kathrin and Steinmann, Joerg and Kleuser, Burkhard and Japtok, Lukasz and Luginbuehl, Miriam and Wolfmeier, Heidi and Scherag, Andre and Gulbins, Erich and Kadioglu, Aras and Draeger, Annette and Babiychuk, Eduard B.}, title = {Engineered liposomes sequester bacterial exotoxins and protect from severe invasive infections in mice}, series = {Nature biotechnology : the science and business of biotechnology}, volume = {33}, journal = {Nature biotechnology : the science and business of biotechnology}, number = {1}, publisher = {Nature Publ. Group}, address = {New York}, issn = {1087-0156}, doi = {10.1038/nbt.3037}, pages = {81 -- U295}, year = {2015}, abstract = {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.}, language = {en} } @article{NojimaFreemanSchusteretal.2016, author = {Nojima, Hiroyuki and Freeman, Christopher M. and Schuster, Rebecca M. and Japtok, Lukasz and Kleuser, Burkhard and Edwards, Michael J. and Gulbins, Erich and Lentsch, Alex B.}, title = {Hepatocyte exosomes mediate liver repair and regeneration via sphingosine-1-phosphate}, series = {Journal of hepatology}, volume = {64}, journal = {Journal of hepatology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0168-8278}, doi = {10.1016/j.jhep.2015.07.030}, pages = {60 -- 68}, year = {2016}, abstract = {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.}, language = {en} } @article{SchumacherChakrabortyKleuseretal.2015, author = {Schumacher, Fabian and Chakraborty, Sudipta and Kleuser, Burkhard and Gulbins, Erich and Schwerdtle, Tanja and Aschner, Michael A. and Bornhorst, Julia}, title = {Highly sensitive isotope-dilution liquid-chromatography-electrospray ionization-tandem-mass spectrometry approach to study the drug-mediated modulation of dopamine and serotonin levels in Caenorhabditis elegans}, series = {Talanta : the international journal of pure and applied analytical chemistry}, volume = {144}, journal = {Talanta : the international journal of pure and applied analytical chemistry}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0039-9140}, doi = {10.1016/j.talanta.2015.05.057}, pages = {71 -- 79}, year = {2015}, abstract = {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.}, language = {en} } @article{FolkessonVorkapicGulbinsetal.2017, author = {Folkesson, Maggie and Vorkapic, Emina and Gulbins, Erich and Japtok, Lukasz and Kleuser, Burkhard and Welander, Martin and L{\"a}nne, Toste and W{\aa}gs{\"a}ter, Dick}, title = {Inflammatory cells, ceramides, and expression of proteases in perivascular adipose tissue adjacent to human abdominal aortic aneurysms}, series = {Journal of vascular surgery}, volume = {65}, journal = {Journal of vascular surgery}, number = {4}, publisher = {Elsevier}, address = {New York}, issn = {0741-5214}, doi = {10.1016/j.jvs.2015.12.056}, pages = {1171 -- 1179}, year = {2017}, abstract = {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.}, language = {en} } @article{HollmannWernerAvotaetal.2016, author = {Hollmann, Claudia and Werner, Sandra and Avota, Elita and Reuter, Dajana and Japtok, Lukasz and Kleuser, Burkhard and Gulbins, Erich and Becker, Katrin Anne and Schneider-Schaulies, J{\"u}rgen and Beyersdorf, Niklas}, title = {Inhibition of Acid Sphingomyelinase Allows for Selective Targeting of CD4(+) Conventional versus Foxp3(+) Regulatory T Cells}, series = {The journal of immunology}, volume = {197}, journal = {The journal of immunology}, publisher = {American Assoc. of Immunologists}, address = {Bethesda}, issn = {0022-1767}, doi = {10.4049/jimmunol.1600691}, pages = {3130 -- 3141}, year = {2016}, abstract = {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.}, language = {en} }