Gerd Geisslinger

Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, North Rhine-Westphalia, Germany

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Publications (440)2018.3 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Ceramides (Cer) are mediators of inflammatory processes. In experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), we observed that CerS6 mRNA expression was upregulated 15-fold in peripheral blood leukocytes before the onset of EAE symptoms. In peripheral blood leukocytes from MS patients, a 3.9-fold upregulation was found. Total genetic deletion of CerS6 and the selective deletion of CerS6 in peripheral blood leucocytes exacerbated the progression of clinical symptoms in EAE mice. This was associated with enhanced leukocyte, predominantly neutrophil infiltration and enhanced demyelination in the lumbar spinal cord of EAE mice. Interferon-gamma/tumor necrosis factor alpha (IFN-γ/TNF-α) and granulocyte colony-stimulating factor (G-CSF) both drive EAE development and induce expression of the integrin CD11b and the chemokine receptor CXCR2 and we found they also induce CerS6 expression. In vivo, the genetic deletion of CerS6 enhanced the activation/migration of neutrophils, as reflected by an enhanced upregulation of CD11b and CXCR2. In vivo, the genetic deletion of CerS6 enhanced the activation status of IFN-γ/TNF-α-stimulated neutrophils, as shown by increased expression of nitric oxide (NO) and CD11b and an increased adhesion capacity. In G-CSF-stimulated neutrophils, the migration status was enhanced, as reflected by an elevated level of CXCR2 and an increased migration capacity. These data suggest that CerS6/C16-Cer mediates feedback regulation by inhibiting the formation of CD11b and CXCR2 which are induced either by IFN-γ/TNF-α or by G-CSF, respectively. We conclude that CerS6/C16-Cer mediates anti-inflammatory effects during the development of EAE and MS possibly by suppressing the migration and deactivation of neutrophils.Immunology and Cell Biology accepted article preview online, 02 April 2015. doi:10.1038/icb.2015.47.
    Immunology and Cell Biology 04/2015; DOI:10.1038/icb.2015.47 · 4.21 Impact Factor
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    ABSTRACT: Prostaglandin E2 (PGE2) favors multiple aspects of tumor development and immune evasion. Therefore, microsomal prostaglandin E synthase (mPGES-1/-2), is a potential target for cancer therapy. We explored whether inhibiting mPGES-1 in human and mouse models of breast cancer affects tumor-associated immunity. A new model of breast tumor spheroid killing by human PBMCs was developed. In this model, tumor killing required CD80 expression by tumor-associated phagocytes to trigger cytotoxic T cell activation. Pharmacological mPGES-1 inhibition increased CD80 expression, whereas addition of PGE2, a prostaglandin E2 receptor 2 (EP2) agonist, or activation of signaling downstream of EP2 reduced CD80 expression. Genetic ablation of mPGES-1 resulted in markedly reduced tumor growth in PyMT mice. Macrophages of mPGES-1-/- PyMT mice indeed expressed elevated levels of CD80 compared to their wildtype counterparts. CD80 expression in tumor-spheroid infiltrating mPGES-1-/- macrophages translated into antigen-specific cytotoxic T cell activation. In conclusion, mPGES-1 inhibition elevates CD80 expression by tumor-associated phagocytes to restrict tumor growth. We propose that mPGES-1 inhibition in combination with immune cell activation might be part of a therapeutic strategy to overcome the immunosuppressive tumor microenvironment.
    Oncotarget 03/2015; · 6.63 Impact Factor
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    ABSTRACT: Nucleosides and nucleoside triphosphates are the building blocks of nucleic acids and important bioactive metabolites, existing in all living cells. In the present study, two liquid chromatography tandem mass spectrometry methods were developed to quantify both groups of compounds from the same sample with a shared extraction procedure. After a simple protein precipitation with methanol, the nucleosides were separated with reversed phase chromatography on an Atlantis T3 column while for the separation of the nucleoside triphosphates, an anion exchange column (BioBasic AX) was used. No addition of ion pair reagent was required. A 5500 QTrap was used as analyzer, operating as triple quadrupole. The analytical method for the nucleoside triphosphates has been validated according to the guidelines of the US Food and Drug Administration. The lower limit of quantification values were determined as 10 pg on column (0.5 ng/mL in the injection solution) for deoxyadenosine triphosphate and deoxyguanosine triphosphate, 20 pg (1 ng/mL) for deoxycytidine triphosphate and thymidine triphosphate, 100 pg (5 ng/mL) for cytidine triphosphate and guanosine triphosphate, and 500 pg (25 ng/mL) for adenosine triphosphate und uridine triphosphate respectively. This methodology has been applied to the quantitation of nucleosides and nucleoside triphosphates in primary human CD4 T lymphocytes and macrophages. As expected, the concentrations for ribonucleosides and ribonucleoside triphophates were considerably higher than those obtained for the deoxy derivatives. Upon T cell receptor activation, the levels of all analytes, with the notable exceptions of deoxyadenosine triphosphate and deoxyguanosine triphosphate, were found to be elevated in CD4 T cells.
    Analytical and Bioanalytical Chemistry 03/2015; epub. · 3.58 Impact Factor
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    ABSTRACT: Nucleosides and nucleoside triphosphates are the building blocks of nucleic acids and important bioactive metabolites, existing in all living cells. In the present study, two liquid chromatography tandem mass spectrometry methods were developed to quantify both groups of compounds from the same sample with a shared extraction procedure. After a simple protein precipitation with methanol, the nucleosides were separated with reversed phase chromatography on an Atlantis T3 column while for the separation of the nucleoside triphosphates, an anion exchange column (BioBasic AX) was used. No addition of ion pair reagent was required. A 5500 QTrap was used as analyzer, operating as triple quadrupole. The analytical method for the nucleoside triphosphates has been validated according to the guidelines of the US Food and Drug Administration. The lower limit of quantification values were determined as 10 pg on column (0.5 ng/mL in the injection solution) for deoxyadenosine triphosphate and deoxyguanosine triphosphate, 20 pg (1 ng/mL) for deoxycytidine triphosphate and thymidine triphosphate, 100 pg (5 ng/mL) for cytidine triphosphate and guanosine triphosphate, and 500 pg (25 ng/mL) for adenosine triphosphate und uridine triphosphate respectively. This methodology has been applied to the quantitation of nucleosides and nucleoside triphosphates in primary human CD4 T lymphocytes and macrophages. As expected, the concentrations for ribonucleosides and ribonucleoside triphophates were considerably higher than those obtained for the deoxy derivatives. Upon T cell receptor activation, the levels of all analytes, with the notable exceptions of deoxyadenosine triphosphate and deoxyguanosine triphosphate, were found to be elevated in CD4 T cells.
    Analytical and Bioanalytical Chemistry 03/2015; DOI:10.1007/s00216-015-8588-3 · 3.58 Impact Factor
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    ABSTRACT: Human experimental pain models are widely used to study drug effects under controlled conditions, but they require further optimization to better reflect clinical pain conditions. To this end, we measured experimentally induced pain in 110 (46 men) healthy volunteers. The quantitative sensory testing (QST) battery (German Research Network on Neuropathic Pain) was applied on untreated ("control") and topical capsaicin-hypersensitized ("test") skin. Z-transformed QST-parameter values obtained at the test site were compared with corresponding values published from 1236 patients with neuropathic pain using Bayesian statistics. Subjects were clustered for the resemblance of their QST pattern to neuropathic pain. Although QST parameter values from the untreated site agreed with reference values, several QST parameters acquired at the test site treated with topical capsaicin deviated from normal. These deviations resembled in 0 to 7 parameters of the QST pattern observed in patients with neuropathic pain. Higher degrees (50%-60%) of resemblance to neuropathic QST pattern were obtained in 18% of the subjects. Inclusion in the respective clusters was predictable at a cross-validated accuracy of 86.9% by a classification and regression tree comprising 3 QST parameters (mechanical pain sensitivity, wind-up ratio, and z-transformed thermal sensory limen) from the control sites. Thus, we found that topical capsaicin partly induced the desired clinical pattern of neuropathic pain in a preselectable subgroup of healthy subjects to a degree that fuels expectations that experimental pain models can be optimized toward mimicking clinical pain. The subjects, therefore, qualify for enrollment in analgesic drug studies that use highly selected cohorts to enhance predictivity for clinical analgesia.
    Pain 03/2015; 156(3):405-14. DOI:10.1097/01.j.pain.0000460328.10515.c9 · 5.84 Impact Factor
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    ABSTRACT: Ceramide synthases (CerS) synthesise ceramides of defined acyl chain lengths, which are thought to mediate cellular processes in a chain length-dependent manner. In experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), we observed a significant elevation of CerS2 and its products, C24-ceramides, in CD11b(+) cells (monocytes and neutrophils) isolated from blood. This result correlates with the clinical finding that CerS2 mRNA expression and C24-ceramide levels were significantly increased by 2.2- and 1.5-fold, respectively, in white blood cells of MS patients. The increased CerS2 mRNA/C24-ceramide expression in neutrophils/monocytes seems to mediate pro-inflammatory effects, since a specific genetic deletion of CerS2 in blood cells or a total genetic deletion of CerS2 significantly delayed the onset of clinical symptoms, due to a reduced infiltration of immune cells, in particular neutrophils, into the central nervous system. CXCR2 chemokine receptors, expressed on neutrophils, promote the migration of neutrophils into the central nervous system, which is a prerequisite for the recruitment of further immune cells and the inflammatory process that leads to the development of MS. Interestingly, neutrophils isolated from CerS2 null EAE mice, as opposed to WT EAE mice, were characterised by significantly lower CXCR2 receptor mRNA expression resulting in their reduced migratory capacity towards CXCL2. Most importantly, G-CSF-induced CXCR2 expression was significantly reduced in CerS2 null neutrophils and their migratory capacity was significantly impaired. In conclusion, our data strongly indicate that G-CSF-induced CXCR2 expression is regulated in a CerS2-dependent manner and that CerS2 thereby promotes the migration of neutrophils, thus, contributing to inflammation and the development of EAE and MS. Copyright © 2015. Published by Elsevier Inc.
    Brain Behavior and Immunity 02/2015; DOI:10.1016/j.bbi.2015.02.010 · 6.13 Impact Factor
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    ABSTRACT: Abstract FTY720 (fingolimod) is after its phosphorylation by sphingosine kinase (SPHK) 2 a potent, non-selective sphingosine-1-phosphate (S1P) receptor agonist. FTY720 has been shown to reduce the nociceptive behaviour in the paclitaxel model for chemotherapy-induced neuropathic pain through downregulation of S1P receptor 1 (S1P1) in microglia of the spinal cord. Here, we investigated the mechanisms underlying the antinociceptive effects of FTY720 in a model for trauma-induced neuropathic pain. We found that intrathecal administration of phosphorylated FTY720 (FTY720-P) decreased trauma-induced pain behaviour in mice, while intraplantar administered FTY720-P had no effect. FTY720-P, but not FTY720, reduced the nociceptive behaviour in SPHK2-deficient mice suggesting the involvement of S1P receptors. Fittingly, intrathecal administration of antagonists for S1P1 or S1P3, W146 and Cay10444 respectively, abolished the antinociceptive effects of systemically administered FTY720, demonstrating that activation of both receptors in the spinal cord is necessary to induce antinociceptive effects by FTY720. Accordingly, intrathecal administration of S1P1 receptor agonists was not sufficient to evoke an antinociceptive effect. Taken together, the data show that, in contrast to its effects on chemotherapy-induced neuropathy, FTY720 reduces trauma-induced neuropathic pain by simultaneous activation of spinal S1P1 and S1P3 receptor subtypes.
    Biological Chemistry 01/2015; DOI:10.1515/hsz-2014-0276 · 2.69 Impact Factor
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    ABSTRACT: Slack (Slo2.2) is a sodium-activated potassium channel that regulates neuronal firing activities and patterns. Previous studies identified Slack in sensory neurons, but its contribution to acute and chronic pain in vivo remains elusive. Here we generated global and sensory neuron-specific Slack mutant mice and analyzed their behavior in various animal models of pain. Global ablation of Slack led to increased hypersensitivity in models of neuropathic pain, whereas the behavior in models of inflammatory and acute nociceptive pain was normal. Neuropathic pain behaviors were also exaggerated after ablation of Slack selectively in sensory neurons. Notably, the Slack opener loxapine ameliorated persisting neuropathic pain behaviors. In conclusion, Slack selectively controls the sensory input in neuropathic pain states, suggesting that modulating its activity might represent a novel strategy for management of neuropathic pain.
    The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 01/2015; 35(3):1125-1135. DOI:10.1523/JNEUROSCI.2423-14.2015 · 6.75 Impact Factor
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    ABSTRACT: Prostaglandin E2 (PGE2) favors multiple aspects of tumor development and immune evasion. Therefore, microsomal prostaglandin E synthase (mPGES-1/-2), is a potential target for cancer therapy. We explored whether inhibiting mPGES-1 in human and mouse models of breast cancer affects tumor-associated immunity. A new model of breast tumor spheroid killing by human PBMCs was developed. In this model, tumor killing required CD80 expression by tumor-associated phagocytes to trigger cytotoxic T cell activation. Pharmacological mPGES-1 inhibition increased CD80 expression, whereas addition of PGE2, a prostaglandin E2 receptor 2 (EP2) agonist, or activation of signaling downstream of EP2 reduced CD80 expression. Genetic ablation of mPGES-1 resulted in markedly reduced tumor growth in PyMT mice. Macrophages of mPGES-1-/- PyMT mice indeed expressed elevated levels of CD80 compared to their wildtype counterparts. CD80 expression in tumor-spheroid infiltrating mPGES-1-/- macrophages translated into antigen-specific cytotoxic T cell activation. In conclusion, mPGES-1 inhibition elevates CD80 expression by tumor-associated phagocytes to restrict tumor growth. We propose that mPGES-1 inhibition in combination with immune cell activation might be part of a therapeutic strategy to overcome the immunosuppressive tumor microenvironment.
    Oncotarget 01/2015; · 6.63 Impact Factor
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    ABSTRACT: Objective. Telaprevir (TVR)-based triple therapy has substantially improved cure rates of hepatitis C virus (HCV) genotype 1 infection but side effects are frequent and often severe. Therefore, response predictors are needed for early identification of patients not responding to TVR-based triple therapy. Material and methods. Forty-five patients (mean age: 54 ± 13 years; male gender: 60%; treatment-experienced: 82%; cirrhosis: 58%) with HCV genotype 1 infection were treated with a TVR-based triple-therapy regimen. TVR plasma levels were analyzed by liquid chromatography electrospray-ionization-tandem mass spectrometry at weeks 2, 4, 8, and 12 of antiviral therapy. On-treatment HCV RNA response was assessed at weeks 4, 12, and 24 by real-time polymerase chain reaction. Results. An extended rapid virological response (eRVR) and sustained virological response (SVR) was achieved in 21 of 45 patients (47%) and 36 of 45 (80%) patients, respectively. Mean ± standard deviation TVR plasma levels at week 2 were 3.4 ± 0.2 log10 ng/ml and did not differ over time (when assessed at weeks 4, 8, and 12). TVR plasma levels at week 2 were significantly higher in patients who achieved an eRVR compared to those who did not achieve eRVR (3.5 ± 0.1 vs. 3.3 ± 0.2 log10 ng/ml; p = 0.003) but were neither associated with SVR nor with treatment-related anemia. Conclusion. TVR plasma levels are associated with on-treatment response but not with overall treatment efficacy. Given the high overall response rates to TVR-based triple therapy, our data suggest that TVR trough levels may not be a useful predictor of treatment response, and routine drug-level monitoring is not required.
    Scandinavian Journal of Gastroenterology 11/2014; DOI:10.3109/00365521.2014.978363 · 2.33 Impact Factor
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    ABSTRACT: Chemotherapy-induced peripheral neuropathic pain (CIPNP)-a severe adverse effect observed in up to 80% of patients during treatment with antineoplastic drugs-limits the tolerable dose of cytostatics, and can lead to discontinuation of chemotherapy. Many drugs that are approved for the treatment of other neuropathic pain states have shown little or no analgesic effect on CIPNP in large randomized, placebo-controlled clinical trials. Here, we review the known mechanisms of CIPNP induced by the three most commonly used cytostatics: paclitaxel, oxaliplatin and vincristine. These substances have distinct neurotoxic and neuroinflammatory properties, but they also have overlapping contributions to pathogenesis of CIPNP that could potentially be targeted for prevention or treatment of CIPNP. We discuss the failure of previously tested antioxidants, neuroprotective agents, anticonvulsants and antidepressants as therapeutic or preventative strategies, and suggest individualized, mechanism-based therapeutic options for CIPNP associated with each of the three main drug groups. We point out the necessity to assess drug efficacy in CIPNP independently of other neuropathic pain states, and emphasize the need for delineation of subpopulations of patients with CIPNP for more-efficient treatment. Finally, we discuss novel therapeutic strategies and recent progress in treatment of CIPNP, and evaluate the potential benefits of these recent proceedings for future therapies.
    Nature Reviews Neurology 11/2014; 10(12). DOI:10.1038/nrneurol.2014.211 · 14.10 Impact Factor
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    ABSTRACT: Ceramide synthases (CerS) are important enzymes of the sphingolipid pathway, responsible for the production of ceramides with distinct chain lengths. In human breast cancer tissue, we detected a significant increase in CerS4 and CerS6 mRNA in estrogen receptor positive (ER+) cancer tissue. To clarify the molecular mechanism of this upregulation, we cloned CerS2,-4, -5 and CerS6 promoter and 3’-UTR fragments into luciferase reporter gene plasmids and determined luciferase activity in MCF-7 (ERα/β) and MDA-MB-231 (ERβ) cells after 17β-estradiol treatment. Only the activities of CerS4 and CerS5 promoter Luc constructs, as well as CerS2- and CerS5 -3’UTR Luc constructs increased after estradiol treatment in MCF-7 cells, and this could be inhibited by the anti-estrogen fulvestrant. Co-transfection with the G protein-coupled estrogen receptor 1 (GPER1) also enhanced CerS2, CerS4 and CerS6 promoter activity whereas CerS5 promoter activity was inhibited in both cell lines. Promoter deletion and mutation constructs from CerS4- and CerS5 promoters revealed that estradiol and GPER1 mediate their effects on both promoters by activating AP-1, most likely through dimerization of c-Jun and c-Fos. At least we could show, that cell proliferation induced by estradiol could be blocked by co-treatment with Fumonisin B1, indicating that upregulation of CerS in breast cancer cells by estrogen is important for cell proliferation and possibly tumor development. In conclusion, our data highlight transcriptional and posttranscriptional mechanisms regulating CerS expression in human cells which provide the basis for further studies investigating the regulation of CerS expression and ceramide synthesis after diverse stimuli in physiological and pathophysiological processess.
    Biochemical Pharmacology 10/2014; DOI:10.1016/j.bcp.2014.10.007 · 4.65 Impact Factor
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    ABSTRACT: Prostanoids, derivatives of arachidonic acid, are involved in inflammation and immune reactions. To understand the role of prostanoids produced by diverse immune cells, a highly sensitive quantitation method for prostaglandin E2 (PGE2), prostaglandin D2 (PGD2), 6-keto prostaglandin F1α (6-keto PGF1α), prostaglandin F2α (PGF2α), and thromboxane B2 (TXB2) by means of nano-liquid chromatography-tandem mass spectrometry has been developed. It was validated according to the guidelines of the Food and Drug Administration (FDA) in terms of linearity, precision, accuracy, recovery, stability, and lower limit of quantitation (LLOQ). The LLOQ were 25 pg/mL in the injected solution (75 fg on column (o.c.)) for PGE2 and PGD2 and 37.5 pg/mL (112.5 fg on column) for 6-keto PGF1α, PGF2α, and TXB2, respectively. It was successfully applied to murine mast cells isolated from paws after zymosan injection and to CD4(+) and CD8(+) T lymphocytes from blood of sensitized versus non-sensitized mice in context of a delayed type hypersensitivity model. About 5,000 (T cells) to 40,000 (mast cells) cells were sufficient for quantitation. In the mast cells, the production of PGE2 increased at a significantly higher extent than the synthesis of the other prostanoids. The T lymphocytes did not show any difference in prostanoid production, no matter whether they were obtained from sensitized mice or non-sensitized mice.
    Analytical and Bioanalytical Chemistry 09/2014; 406(28). DOI:10.1007/s00216-014-8134-8 · 3.58 Impact Factor
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    ABSTRACT: Lipoxins belong to the family of so-called pro-resolving endogenous lipid mediators which are derived from arachidonic acid and play a key role in the counter-regulation of inflammation. Arachidonic acid is also precursor of multiple pro-inflammatory lipid mediators, such as prostaglandins and leukotrienes, which are simultaneously present in biological compartments. The close structural relationship between several of these lipid mediators and the absence of blank matrix samples enormously complicates the unequivocal identification of these compounds. The determination of lipoxin A4 has been accomplished by chromatographic separation using a C18 reversed phase column and tandem mass spectrometry detection. Samples were liquid-liquid extracted with ethyl acetate before injection. Identification of the analyte was done based on three criteria: retention time, ratio of the m/z transitions and MS/MS spectrum. To avoid false positive results due to endogenous interferences, the extracted samples were re-injected into a chiral Lux Amylose-2 chromatographic column. The authors recommend the use of chiral chromatography in the determination of pro-resolving lipid mediators, together with transition area ratio and fragmentation spectra to improve selectivity for identification and quantitation purposes.
    Talanta 09/2014; 127:82–87. DOI:10.1016/j.talanta.2014.03.051 · 3.51 Impact Factor
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    ABSTRACT: R-flurbiprofen is the non-cyclooxygenase inhibiting R-enantiomer of the non-steroidal anti-inflammatory drug flurbiprofen, which was assessed as a remedy for Alzheimer's disease. Because of its anti-inflammatory, endocannabinoid-modulating and antioxidative properties, combined with low toxicity, the present study assessed R-flurbiprofen in experimental autoimmune encephalomyelitis (EAE) models of multiple sclerosis in mice. Oral R-flurbiprofen prevented and attenuated primary progressive EAE in C57BL6/J mice and relapsing-remitting EAE in SJL mice, even if the treatment was initiated on or after the first flare of the disease. R-flurbiprofen reduced immune cell infiltration and microglia activation and inflammation in the spinal cord, brain and optic nerve and attenuated myelin destruction and EAE-evoked hyperalgesia. R-flurbiprofen treatment increased CD4+CD25+FoxP3+ regulatory T cells, CTLA4+ inhibitory T cells and interleukin-10, whereas the EAE-evoked upregulation of pro-inflammatory genes in the spinal cord was strongly reduced. The effects were associated with an increase of plasma and cortical endocannabinoids but decreased spinal prostaglandins, the latter likely due to R to S inversion. The promising results suggest potential efficacy of R-flurbiprofen in human MS, and its low toxicity may justify a clinical trial.
    EMBO Molecular Medicine 09/2014; DOI:10.15252/emmm.201404168 · 8.25 Impact Factor
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    ABSTRACT: Ceramides (Cer) are mediators of inflammatory processes. In a chronic experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis (MS), we observed a significant elevation of C16-Cer and its synthesizing enzyme, ceramide synthase(CerS)6, in the lumbar spinal cord. In the present study, we have confirmed that C16-Cer and CerS6 are also upregulated in the lumbar spinal cord in a spontanous relapse-remitting EAE model, using SJL mice overexpressing a transgenic T cell receptor (TCR1640). CerS6 was found to be expressed in macrophages, T cells and B cells in EAE lesions. In macrophages, we demonstrated that interferon gamma (IFN-γ)-induced CerS6 upregulation was amplified by 17ß-estradiol, an action that was further accompanied by increased upregulation of tumor necrosis factor alpha (TNF-α). Accordingly, CerS6 and TNF-α expression was upregulated predominantly in the spinal cord in female TCR1640 mice, which usually develop the relapse-remitting form of EAE, while male TCR1640 mice showed an attenuated regulation of CerS6 and TNF-α and exhibit mostly chronic disease progression. Furthermore, expression of TNFR2, one of two receptors of TNF-α, which is linked to neuroprotection and remyelination, was also upregulated to a greater extent during EAE in female TCR1640 mice in comparison to male TCR1640 mice. Taken together, our results confirm the upregulation of CerS6 and C16-Cer in an adjuvant-independent, physiological EAE model and further suggest an anti-inflammatory role of CerS6 in the regulation of the disease course in female TCR1640 mice via TNF-α/TNFR2.
    Biochemical Pharmacology 08/2014; DOI:10.1016/j.bcp.2014.08.016 · 4.65 Impact Factor
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    ABSTRACT: CYP inhibitors may reduce opioid analgesia by inhibiting CYP activity dependent post-opioid receptor signaling pathways in the brain. This suggestion was predicated on observations of highly attenuated morphine antinociception in rodents after intracerebroventricular injection of fluconazole or carrying a neuron-specific deletion of the cytochrome P450 reductase. However, based on assessments of thermal and electrical pain tolerance, respiratory function and side effects in 21 healthy volunteers, prior and during steady-state concentrations of remifentanil at effect site (CNS) of 1.5 ng/ml and 3 ng/ml, administration of 400 mg/d fluconazole for 8 days in a double-blind, placebo-controlled manner, failed to attenuate opioid effects. Although CYP inhibitors like fluconazole are unlikely to attenuate remifentanil analgesia in humans, extrapolation of the findings to other opioids is premature because opioid differences, like e.g. ligand-selective biased signaling at opioid receptors, leave the possibility that brain CYP dependent opioid signaling might be limited to morphine but not remifentanil.Clinical Pharmacology & Therapeutics (2014); Accepted article preview online 22 August 2014; doi:10.1038/clpt.2014.169.
    Clinical Pharmacology &#38 Therapeutics 08/2014; 96(6). DOI:10.1038/clpt.2014.169 · 7.39 Impact Factor
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    ABSTRACT: Emerging lines of evidence indicate that production of reactive oxygen species (ROS) at distinct sites of the nociceptive system contributes to the processing of neuropathic pain. However, the mechanisms underlying ROS production during neuropathic pain processing are not fully understood. We here detected the ROS-generating NADPH oxidase isoform Nox2 in macrophages of dorsal root ganglia (DRGs) in mice. In response to peripheral nerve injury, Nox2-positive macrophages were recruited to DRGs, and ROS production was increased in a Nox2-dependent manner. Nox2-deficient mice displayed reduced neuropathic pain behavior after peripheral nerve injury, whereas their immediate responses to noxious stimuli were normal. Moreover, injury-induced upregulation of tumor necrosis factor α was absent and ATF3-induction was reduced in DRGs of Nox2-deficient mice suggesting an attenuated macrophage-neuron signaling. These data suggest that Nox2-dependent ROS production in macrophages recruited to DRGs contributes to neuropathic pain hypersensitivity, underlining the observation that Nox-derived ROS exert specific functions during the processing of pain.
    Pain 08/2014; 155(10). DOI:10.1016/j.pain.2014.08.013 · 5.84 Impact Factor
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    ABSTRACT: Pro-resolving lipid mediators are a class of endogenously synthesized molecules derived from different fatty acids, such as arachidonic, docosahexaenoic or eicosapentaenoic acid, which are derived into four different product families: lipoxins, resolvins, maresins and protectins. For quantitation of these compounds, a sensitive, selective and robust liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous quantitation of lipoxin A4, 6-epi-lipoxin A4, lipoxin B4 and lipoxin A5, the D-series resolvins D1 and D2 as well as aspirin-triggered lipoxin A4 and resolvin D1, maresin and protectin and the pathway markers 17(S)-hydroxy-docosahexaenoic acid and 17(R)-hydroxy-docosahexaenoic acid in cell culture supernatants. For this purpose, a chiral column was connected in series with a reversed-phase column to achieve efficient analyte separation and high sensitivity. Sample pre-treatment included a fast and simple liquid-liquid extraction procedure. Limits of quantitation in the range of 0.1-0.5ng/mL cell culture media, absolute recoveries between 90 and 115%, intra- and interday precision of less than 13% and an accuracy of less than 11% were obtained. Stability of the samples after 60 days storage at -80°C, three freeze/thaw cycles and 4h at room temperature has been demonstrated for all analytes. Sample extracts can be stored at 7°C for 24h without degradation of the analytes. Deviations of less than 13% in the accuracy, evaluated in terms of relative error, were obtained. The suitability of the method has been demonstrated in cell culture supernatants of human polymorphonuclear leukocytes, stimulated with 15R-hydroxy-eicosatetraenoic acid and in cell culture media of human polymorphonuclear leukocytes co-incubated with human platelets. From all studied analytes, lipoxin A4 and 6-epi-lipoxin A4 were found in cell culture media under both incubation conditions, while 15-epi-lipoxin A4 was additionally detected in cell culture supernatants of polymorphonuclear leukocytes stimulated with 15R-hydroxy-eicosatetraenoic acid.
    Journal of Chromatography A 07/2014; 1360. DOI:10.1016/j.chroma.2014.07.068 · 4.26 Impact Factor
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    ABSTRACT: Prostaglandins (PGs) act as potent local hormones in nearly all tissues of the human body and are used for various medical applications. Heterologous expression of PG endoperoxide H-synthase from the alga, Gracilaria vermiculophylla, into E. coli and the application of this strain in biotransformation experiments resulted in a highly efficient conversion of arachidonic acid (ARA) yielding up to 130 mg natural PGs l(-1) in a laboratory scale approach. Detailed analyses of the products and production kinetics were performed, confirming a rapid conversion of ARA to PGs.
    Biotechnology Letters 07/2014; 36(11). DOI:10.1007/s10529-014-1610-6 · 1.74 Impact Factor

Publication Stats

12k Citations
2,018.30 Total Impact Points

Institutions

  • 2015
    • Fraunhofer Institute for Molecular Biology and Applied Ecology IME
      Aachen, North Rhine-Westphalia, Germany
  • 2000–2015
    • Goethe-Universität Frankfurt am Main
      • • Institut für Klinische Pharmakologie
      • • Institut für Pharmazeutische Biologie
      • • Institut für Allgemeine Pharmakologie und Toxikologie
      • • Zentrum der Pharmakologie
      Frankfurt, Hesse, Germany
  • 2005–2014
    • University Hospital Frankfurt
      Frankfurt, Hesse, Germany
    • University of Western Australia
      • School of Medicine and Pharmacology
      Perth City, Western Australia, Australia
  • 2008–2012
    • Hospital Frankfurt Hoechst
      Frankfurt, Hesse, Germany
  • 2011
    • University of Toronto
      Toronto, Ontario, Canada
  • 2000–2011
    • Institut für klinische Pharmakologie
      Stuttgart, Baden-Württemberg, Germany
  • 2007
    • Harvard University
      Cambridge, Massachusetts, United States
  • 1989–2006
    • Friedrich-Alexander Universität Erlangen-Nürnberg
      • • Department of Ophthalmology
      • • Department of Experimental and Clinical Pharmacology and Toxicology
      • • Department of Anaesthesiology
      Erlangen, Bavaria, Germany
  • 1989–2000
    • Universitätsklinikum Erlangen
      Erlangen, Bavaria, Germany
  • 1999
    • Stanford University
      • Department of Anesthesia
      Palo Alto, California, United States
  • 1998
    • Hadassah Medical Center
      • Department of Medicine
      Jerusalem, Jerusalem District, Israel
  • 1996
    • University of New South Wales
      Kensington, New South Wales, Australia
    • Karl-Franzens-Universität Graz
      Gratz, Styria, Austria
  • 1992–1995
    • St. Vincent's Hospital Sydney
      • Clinical Pharmacology and Toxicology
      Sydney, New South Wales, Australia
  • 1994
    • Ruhr-Universität Bochum
      • Institute of Pharmacology and Toxicology
      Bochum, North Rhine-Westphalia, Germany