Bjarne Krebs

Publications of Bjarne Krebs

• Imaging of integrin {alpha}v{beta}3 expression in patients with malignant glioma by [18F]galacto-RGD positron emission tomography.

  Authors: Oliver Schnell, Bjarne Krebs, Janette Carlsen, Isabelle Miederer, Claudia Goetz, Roland H Goldbrunner, Hans-Jürgen Wester, Roland Haubner, Gabriele Pöpperl, Markus Holtmannspötter, Hans A Kretzschmar, Horst Kessler, Jörg-Christian Tonn, Markus Schwaiger, Ambros J Beer

  Neuro-oncology. 05/2009;

  Inhibitors targeting the integrin alphavbeta3 are promising new agents currently tested in clinical trials for supplemental therapy of glioblastoma multiforme (GBM). The aim of our study was toInhibitors targeting the integrin alphavbeta3 are promising new agents currently tested in clinical trials for supplemental therapy of glioblastoma multiforme (GBM). The aim of our study was to evaluate [18F]Galacto-RGD positron emission tomography (PET) for non-invasive imaging of alphavbeta3 expression in patients with GBM suggesting eligibility for this kind of additional treatment. Patients with suspected or recurrent GBM were examined with [18F]Galacto-RGD PET. Standardized uptake values (SUVs) of tumor hotspots, galea and blood pool were derived by region-of-interest analysis. [18F]Galacto-RGD PET images were fused with cranial MRI scans for image guided surgery. Tumor samples taken from areas with intense tracer accumulation in the [18F]Galacto-RGD PET were analyzed histologically and immunhistochemically for alphavbeta3 integrin expression. While normal brain tissue did not show significant tracer accumulation (mean SUV 0.09 +/- 0.04), GBMs demonstrated significant but heterogeneous tracer uptake with a maximum in the highly proliferating and infiltrating areas of tumors (mean SUV 1.6 +/- 0.5). Immunohistochemical staining was prominent in tumor microvessels as well as glial tumor cells. In areas of highly proliferating glial tumor cells, tracer uptake (SUVs) in the [18F]Galacto-RGD PET correlated to the immunohistochemical alphavbeta3 integrin expression of corresponding tumor samples. These data suggest that [18F]Galacto-RGD PET successfully identifies alphavbeta3 expression in patients with GBM and might be a promising tool for planning and monitoring individualized cancer therapies targeting this integrin.

• oxLDL uptake by dendritic cells induces upregulation of scavenger-receptors, maturation and differentiation.

  Authors: Thomas Nickel, Daniel Schmauss, Henner Hanssen, Zelka Sicic, Bjarne Krebs, Sarika Jankl, Claudia Summo, Peter Fraunberger, Autar K Walli, Susanne Pfeiler, Michael Weis

  Atherosclerosis. 02/2009;

  BACKGROUND: Several studies have proposed a pathogenic role for oxidized LDL (oxLDL) in atherosclerosis. We tested the hypothesis whether oxLDL modulates dendritic cells (DCs), since these importantBACKGROUND: Several studies have proposed a pathogenic role for oxidized LDL (oxLDL) in atherosclerosis. We tested the hypothesis whether oxLDL modulates dendritic cells (DCs), since these important antigen-presenting cells have been implicated in atherogenesis. We investigated the uptake of oxLDL by DCs, the scavenger-receptors involved and the resulting changes in phenotype and cytokine-spectra. In addition, we analyzed the impact of oxLDL on the nuclear transcription factor-kappa B (NF-kappaB)-pathway. METHODS AND RESULTS: oxLDL (10mug/ml) increased the expression of the scavenger-receptors CD205 and CD36 and decreased the mannose-receptor expression. The lectin-like oxLDL-receptor (LOX-1)-expression was not affected. The endocytotic capacity of dextran and lucifer-yellow was moderately decreased by oxLDL. Blockage of the scavenger-receptors CD36, LOX-1 and CD205 reduced oxLDL uptake. Furthermore, oxLDL induced DC-maturation and triggered differentiation of DCs in myeloid and plasmacytoid DCs. oxLDL decreased IL-10 secretion and increased IL-6 release. Finally, oxLDL induced an activation of the NF-kappaB-pathway. Inhibition of IkappaBalpha-phosphorylation diminished the oxLDL-induced DC-maturation and -differentiation. CONCLUSION: oxLDL uptake by DCs is mediated by the scavenger-receptors LOX-1, CD36, and CD205. oxLDL induces a proinflammatory cytokine profile in human DCs leading to DC-maturation and -differentiation which can, in part, be explained by an activation of the NF-kappaB-pathway. These results support the hypothesis that vascular inflammation may be aggravated by oxLDL induced DC-activation.

• Presence of pluripotent CD133(+) cells correlates with malignancy of gliomas.

  Authors: Niklas Thon, Karin Damianoff, Jemima Hegermann, Stefan Grau, Bjarne Krebs, Oliver Schnell, Jörg-Christian Tonn, Roland Goldbrunner

  Molecular and cellular neurosciences. 09/2008;

  BACKGROUND: Presence of CD133(+) cancer stem cells has been demonstrated within glioblastoma multiforme (GBM), the most malignant phenotype of gliomas (WHO grade IV). Since GBM frequently developsBACKGROUND: Presence of CD133(+) cancer stem cells has been demonstrated within glioblastoma multiforme (GBM), the most malignant phenotype of gliomas (WHO grade IV). Since GBM frequently develops from low grade gliomas (WHO grade II) we assessed a possible qualitative or quantitative correlation of CD133(+) cells and glioma grade to get new insights in gliomagenesis. RESULTS: The amount of CD133(+) cells within the bulk tumor mass, analyzed by immunostaining and Western blotting, showed a clear quantitative correlation with glioma grade (WHO degrees II, III and IV). Most of CD133(+) cells were arranged in clusters frequently associated to tumor vessels. Protein analysis revealed high cellular coexpression of CD133 with Musashi-I but not CD34 indicating a neural, i.e. local origin of these cells. In vitro, no differences in stem cell properties concerning self-renewal and multi-lineage differentiation have been found for CD133(+) cells isolated from gliomas of different grades. CONCLUSIONS: These findings indicate a solely quantitative correlation of glioma grade with the presence of neural CD133(+) cells within tumors supporting the concept of a CD133(+) stem cell dependent gliomagenesis.

• Expression of Integrin alpha(v)beta(3) in Gliomas Correlates with Tumor Grade and Is not Restricted to Tumor Vasculature.

  Authors: Oliver Schnell, Bjarne Krebs, Erika Wagner, Alexander Romagna, Ambros J Beer, Stefan J Grau, Niklas Thon, Claudia Goetz, Hans A Kretzschmar, Jörg-Christian Tonn, Roland H Goldbrunner

  Brain pathology (Zurich, Switzerland). 08/2008; 18(3):378-86.

  In malignant gliomas, the integrin adhesion receptors seem to play a key role for invasive growth and angiogenesis. However, there is still a controversy about the expression and the distribution ofIn malignant gliomas, the integrin adhesion receptors seem to play a key role for invasive growth and angiogenesis. However, there is still a controversy about the expression and the distribution of alpha(v)beta(3) integrin caused by malignancy. The aim of our study was to assess the extent and pattern of alpha(v)beta(3) integrin expression within primary glioblastomas (GBMs) compared with low-grade gliomas (LGGs). Tumor samples were immunostained for the detection of alpha(v)beta(3) integrin and quantified by an imaging software. The expression of alpha(v)beta(3) was found to be significantly higher in GBMs than in LGGs, whereby focal strong reactivity was restricted to GBMs only. Subsequent analysis revealed that not only endothelial cells but also, to a large extent, glial tumor cells contribute to the overall amount of alpha(v)beta(3) integrin in the tumors. To further analyze the integrin subunits, Western blots from histologic sections were performed, which demonstrated a significant difference in the expression of the beta(3) integrin subunit between GBMs and LGGs. The presented data lead to new insights in the pattern of alpha(v)beta(3) integrin in gliomas and are of relevance for the inhibition of alpha(v)beta(3) integrin with specific RGD peptides and interfering drugs to reduce angiogenesis and tumor growth.

• Evidence for a pathogenic role of different mutations at codon 188 of PRNP.

  Authors: Sigrun Roeber, Eva-Maria Grasbon-Frodl, Otto Windl, Bjarne Krebs, Wei Xiang, Caren Vollmert, Thomas Illig, Andreas Schröter, Thomas Arzberger, Petra Weber, Inga Zerr, Hans A Kretzschmar

  PLoS ONE. 02/2008; 3(5):e2147.

  Clinical and pathological changes in familial Creutzfeldt-Jakob disease (CJD) cases may be similar or indistinguishable from sporadic CJD. Therefore determination of novel mutations in PRNP remainsClinical and pathological changes in familial Creutzfeldt-Jakob disease (CJD) cases may be similar or indistinguishable from sporadic CJD. Therefore determination of novel mutations in PRNP remains of major importance.We identified two different rare mutations in codon 188 of the prion protein gene (PRNP) in four patients suffering from a disease clinically very similar to the major subtype of sporadic CJD. Both mutations result in an exchange of the amino acid residue threonine for a highly basic residue, either arginine (T188R) or lysine (T188K). The T188R mutation was found in one patient and the T188K mutation in three patients. The prevalence of mutations at codon 188 of PRNP was tested in 593 sporadic CJD cases and 735 healthy individuals. Neither mutation was found. The data presented here argue in favor of T188K being a pathogenic mutation causing genetic CJD. Since one individual with this mutation, who is the father of a clinically affected patient with T188K mutation, is now 79 years old and shows no signs of disease, this mutation is likely associated with a penetrance under 100%. Further observations will have to show whether T188R is a pathogenic mutation.

• Erratum.

  Authors: Sigrun Roeber, Eva-Maria Grasbon-Frodl, Otto Windl, Bjarne Krebs, Wei Xiang, Caren Vollmert, Thomas Illig, Andreas Schröter, Thomas Arzberger, Petra Weber, Inga Zerr, Hans A Kretzschmar

  PLoS ONE. 02/2008; 3(5).

  [This corrects the article on p. e2147 in vol. 3, PMID: 18478114.].

• A novel subtype of Creutzfeldt-Jakob disease characterized by a small 6 kDa PrP fragment.

  Authors: Bjarne Krebs, Benedikt Bader, Juliane Klehmet, Eva Grasbon-Frodl, Wolfgang H Oertel, Inga Zerr, Sarah Stricker, Rolf Zschenderlein, Hans A Kretzschmar

  Acta neuropathologica. 09/2007; 114(2):195-9.

  We report on a novel subtype of Creutzfeldt-Jakob disease with a single proteinase K-resistant prion protein fragment of about 6 kDa in Western blots of brain homogenates. Clinically this patientWe report on a novel subtype of Creutzfeldt-Jakob disease with a single proteinase K-resistant prion protein fragment of about 6 kDa in Western blots of brain homogenates. Clinically this patient showed a progressive spastic disorder and dementia over 3 years. No mutation of the prion protein gene was found. Since this patient had received a blood transfusion, an iatrogenic cause, albeit unlikely, cannot be ruled out. Future studies will have to be attentive to small prion protein fragments, which may cause or be associated with unusual clinical disease that might possibly only be diagnosed by immunoblotting of brain homogenates.

• The role of the octarepeat region in neuroprotective function of the cellular prion protein.

  Authors: Gerda Mitteregger, Milan Vosko, Bjarne Krebs, Wei Xiang, Veronika Kohlmannsperger, Svenja Nölting, Gerhard F Hamann, Hans A Kretzschmar

  Brain pathology (Zurich, Switzerland). 05/2007; 17(2):174-83.

  Structural alterations of the cellular prion protein (PrP(C)) seem to be the core of the pathogenesis of prion diseases. However, the physiological function of PrP(C )remains an enigma. Cell cultureStructural alterations of the cellular prion protein (PrP(C)) seem to be the core of the pathogenesis of prion diseases. However, the physiological function of PrP(C )remains an enigma. Cell culture experiments have indicated that PrP(C) and in particular its N-terminal octarepeat region together with the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways have a fundamental involvement in neuroprotection and oxidative stress reactions. We used wild-type mice, PrP knockout (Prnp(-/-)) animals and transgenic mice that lack the octarepeat region (C4/-) and subjected them to controlled ischemia. We identified an increased cleavage and synthesis of PrP(C) in ischemic brain areas of wild-type mice compared with sham controls. The infarct size in Prnp(-/-) animals was increased threefold when compared with wild-type mice. The infarct size in C4/- animals was identical to Prnp(-/-) mice, that is, around three times larger than in wild-type mice. We showed that the PrP in C4/- mice does not functionally rescue the Prnp(-/-) phenotype; furthermore it is unable to undergo beta cleavage, although an increased amount of C1 fragments was found in ischemic brain areas compared with sham controls. We demonstrated that the N-terminal octarepeat region has a lead function in PrP(C) physiology and neuroprotection against oxidative stress in vivo.

• Cellular prion protein modulates the intracellular calcium response to hydrogen peroxide.

  Authors: Bjarne Krebs, Antje Wiebelitz, Beate Balitzki-Korte, Neville Vassallo, Sandra Paluch, Gerda Mitteregger, Takashi Onodera, Hans A Kretzschmar, Jochen Herms

  Journal of neurochemistry. 02/2007; 100(2):358-67.

  The physiological function of the cellular prion protein (PrP(C)) is still under intense investigation. It has been suggested that PrP(C) has a protective role in neuronal cells, particularly againstThe physiological function of the cellular prion protein (PrP(C)) is still under intense investigation. It has been suggested that PrP(C) has a protective role in neuronal cells, particularly against environmental stress caused by reactive oxygen species (ROS). Here we analysed the acute effect of a major ROS, hydrogen peroxide (H(2)O(2)), on intracellular calcium homeostasis in cultured cerebellar granule cells and immortalized hippocampal neuronal cells. Both neuronal cell culture models showed that the rise in intracellular calcium following application of H(2)O(2) was strongly dependent on the presence of PrP(C). Moreover, the N-terminal octapeptide repeats of PrP(C) were required for this effect, because neuronal cells expressing a PrP(C) lacking the N-terminus resembled the PrP(C)-deficient phenotype. Neurones deficient of fyn kinase, or pharmacological inhibition of fyn, also abrogated the calcium response to H(2)O(2) treatment, indicating that fyn activation is a critical step within the PrP(C) signalling cascade. Finally, we identified a possible role of this PrP(C) signalling pathway in the neuroprotective response of PrP(C) to oxidative stress. In conclusion, we put forward the hypothesis that PrP(C) functions as a sensor for H(2)O(2), thereby activating a protective signalling cascade involving fyn kinase that leads to calcium release from intracellular stores.

• Brain protein preservation largely depends on the postmortem storage temperature: implications for study of proteins in human neurologic diseases and management of brain banks: a BrainNet Europe Study.

  Authors: Isidre Ferrer, Gabriel Santpere, Thomas Arzberger, Jeanne Bell, Rosa Blanco, Susana Boluda, Herbert Budka, Margarita Carmona, Giorgio Giaccone, Bjarne Krebs, Lucia Limido, Piero Parchi, Berta Puig, Rosaria Strammiello, Thomas Ströbel, Hans Kretzschmar

  Journal of neuropathology and experimental neurology. 02/2007; 66(1):35-46.

  The present study was designed to reveal protein modifications in control cases related with postmortem delay and temperature of storage in 3 paradigms in which the same postmortem tissue sampleThe present study was designed to reveal protein modifications in control cases related with postmortem delay and temperature of storage in 3 paradigms in which the same postmortem tissue sample (frontal cortex) was frozen a short time after death or stored at 1 degrees C, 4 degrees C, or room temperature and then frozen at -80 degrees C at different intervals. No evidence of protein degradation as revealed with monodimensional gel electrophoresis and Western blotting was observed in samples artificially stored at 1 degrees C and then frozen at different intervals up to 50 hours after death. However, the levels of several proteins were modified in samples stored at 4 degrees C and this effect was more marked in samples stored at room temperature. Two-dimensional gel electrophoresis and mass spectrometry further corroborated these observations and permitted the identification of other proteins vulnerable or resistant to postmortem delay. Finally, gel electrophoresis and Western blotting of sarkosyl-insoluble fractions in Alzheimer disease showed reduced intensity of phospho-tau-specific bands with postmortem delay with the effects being more dramatic when the brain samples were stored at room temperature for long periods. These results emphasize the necessity of reducing the body temperature after death to minimize protein degradation.

• Dose-related influence of sodium selenite on apoptosis in human thyroid follicles in vitro induced by iodine, EGF, TGF-beta, and H2O2.

  Authors: Petra Lehmann, Petra Rank, Klaus L J Hallfeldt, Bjarne Krebs, Roland Gärtner

  Biological trace element research. 08/2006; 112(2):119-30.

  Apoptosis of thyroid follicular cells is induced by high doses of iodide, epidermal growth factor (EGF), transforming growth factor-beta (TGF-beta), as well as H2O2 and might be attenuated byApoptosis of thyroid follicular cells is induced by high doses of iodide, epidermal growth factor (EGF), transforming growth factor-beta (TGF-beta), as well as H2O2 and might be attenuated by antioxidants. Therefore, we examined the apoptotic index induced by these substances in selenium-treated vs untreated human thyroid follicular cells. Reconstituted human thyroid follicles were incubated with sodium selenite (10 or 100 nM) for 72 h; controls received none. The follicles were then distributed to 24-well plates and incubated with potassium iodide (5, 10, or 20 nM), EGF (5 ng/mL), TGF-beta (5 ng/mL), or H2O2 (100 muM). Apoptosis was determined by a mitochondrial potential assay and the number of apoptotic cells counted by two independent, experienced technicians and the glutathione peroxidase (GPx) activity was determined. Asignificant increase of apoptic cells was obtained in control thyroid follicles treated with iodine (5, 10, or 20 microM), thyroidstimulating hormone (TSH) 1, or 10 mU/mL in combination with 5 and 10 microM iodine, EGF (5 ng/mL) and TGF-beta (5 ng/mL), or H2O2 (100 microM) (p < 0.001). In contrast, in thyroid follicles preincubated with 10 or 100 nM sodium selenite, the apoptototic index was identical to the basal rate. In H2O2-treated follicles, the apoptotic index was still significantly elevated but 50% lower compared to control cells. The GPx activity increased from 1.4 +/- 0.2 to 2.25 +/- 0.4 mU/microg DNA with 10 nMselenite and 2.6 + 0.4 mU/microg DNA with 100 nM selenite. Sodium selenite might increase the antioxidative potential in human thyroid follicles in vitro and therefore diminish the apoptosis induced by TGF-beta, EGF, iodide, and even H2O2.

• Synapse formation and function is modulated by the amyloid precursor protein.

  Authors: Christina Priller, Thomas Bauer, Gerda Mitteregger, Bjarne Krebs, Hans A Kretzschmar, Jochen Herms

  The Journal of neuroscience : the official journal of the Society for Neuroscience. 08/2006; 26(27):7212-21.

  The amyloid precursor protein (APP) is critical in the pathogenesis of Alzheimer's disease. The question of its normal biological function in neurons, in which it is predominantly located atThe amyloid precursor protein (APP) is critical in the pathogenesis of Alzheimer's disease. The question of its normal biological function in neurons, in which it is predominantly located at synapses, is still unclear. Using autaptic cultures of hippocampal neurons, we demonstrate that hippocampal neurons lacking APP show significantly enhanced amplitudes of evoked AMPA- and NMDA-receptor-mediated EPSCs. The size of the readily releasable synaptic vesicle pool was also increased in neurons lacking APP, whereas the release probability was not affected. In addition, the analysis of spontaneous miniature synaptic currents revealed an augmented frequency in neurons lacking APP, whereas the amplitude of miniature synaptic currents was not found to be altered. Together, these findings strongly indicate that lack of APP increases the number of functional synapses. This hypothesis is further supported by morphometric immunohistochemical analysis revealing an increase of synaptophysin-positive puncta per cultured APP knock-out neuron. In conclusion, lack of APP affects synapse formation and transmission in cultured hippocampal neurons.

• A method to perform Western blots of microscopic areas of histological sections.

  Authors: Bjarne Krebs, Veronika Kohlmannsperger, Svenja Nölting, Rüdiger Schmalzbauer, Hans A Kretzschmar

  The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society. 06/2006; 54(5):559-65.

  Western blotting is one powerful research method to specifically detect proteins. However, it has been barely possible to investigate microscopic volumes of tissue so far because of the requiredWestern blotting is one powerful research method to specifically detect proteins. However, it has been barely possible to investigate microscopic volumes of tissue so far because of the required minimum volumes and the pretreatment. Herein, we describe a method of performing Western blots directly from the histological section of frozen or paraffin-embedded tissue. Small histological areas of a mouse brain were lysed by section lysis buffer, subjected to a miniaturized SDS-PAGE, and detected by immunoblotting. Thereby, an area equivalent to only 15 cortical neurons of mouse cortex was detectable. This offers the possibility of correlating histological findings to biochemical investigations. In addition, enzymatic pretreatment was applied to identify the glycosylation of the major cleavage product of the prion protein. Moreover, the section lysis buffer is a sophisticated method to conserve and investigate phosphorylation sites as demonstrated here by phopsphorylated Akt and ERK. The presented technique combines histology with Western blotting techniques and will be of value for investigations of discrete tissue areas.

• Prion protein induced signaling cascades in monocytes.

  Authors: Bjarne Krebs, Cornelia Dorner-Ciossek, Rüdiger Schmalzbauer, Neville Vassallo, Jochen Herms, Hans A Kretzschmar

  Biochemical and biophysical research communications. 03/2006; 340(1):13-22.

  Prion proteins play a central role in transmission and pathogenesis of transmissible spongiform encephalopathies. The cellular prion protein (PrP(C)), whose physiological function remains elusive, isPrion proteins play a central role in transmission and pathogenesis of transmissible spongiform encephalopathies. The cellular prion protein (PrP(C)), whose physiological function remains elusive, is anchored to the surface of a variety of cell types including neurons and cells of the lymphoreticular system. In this study, we investigated the response of a mouse monocyte/macrophage cell line to exposure with PrP(C) fusion proteins synthesized with a human Fc-tag. PrP(C) fusion proteins showed an attachment to the surface of monocyte/macrophages in nanomolar concentrations. This was accompanied by an increase of cellular tyrosine phosphorylation as a result of activated signaling pathways. Detailed investigations exhibited activation of downstream pathways through a stimulation with PrP fusion proteins, which include phosphorylation of ERK(1,2) and Akt kinase. Macrophages opsonize and present antigenic structures, contact lymphocytes, and deliver cytokines. The findings reported here may become the basis of understanding the molecular function of PrP(C) in monocytes and macrophages.

• Activation of phosphatidylinositol 3-kinase by cellular prion protein and its role in cell survival.

  Authors: Neville Vassallo, Jochen Herms, Christina Behrens, Bjarne Krebs, Keiichi Saeki, Takashi Onodera, Otto Windl, Hans A Kretzschmar

  Biochemical and biophysical research communications. 07/2005; 332(1):75-82.

  The cellular prion protein (PrP(C)) is thought to be involved in protection against cell death, however the exact cellular mechanisms involved are still controversial. Herein we present data thatThe cellular prion protein (PrP(C)) is thought to be involved in protection against cell death, however the exact cellular mechanisms involved are still controversial. Herein we present data that strongly indicate a functional link between PrP(C) expression and phosphatidylinositol 3-kinase (PI 3-kinase) activation, a protein kinase that plays a pivotal role in cell survival. Both mouse neuroblastoma N2a cells and immortalized murine hippocampal neuronal cell lines expressing wild-type PrP(C) had significantly higher PI 3-kinase activity levels than their respective controls. Moreover, PI 3-kinase activity was found to be elevated in brain lysates from wild-type mice, as compared to prion protein-knockout mice. Recruitment of PI 3-kinase by PrP(C) was shown to contribute to cellular survival toward oxidative stress by using 3-morpholinosydnonimine (SIN-1) and serum deprivation. Moreover, both PI 3-kinase activation and cytoprotection by PrP(C) appeared to rely on copper binding to the N-terminal octapeptide of PrP(C). Thus, we propose a model in which the interaction of copper(II) with the N-terminal domain of PrP(C) enables transduction of a signal to PI 3-kinase; the latter, in turn, mediates downstream regulation of cell survival.

• Creutzfeldt-Jakob disease associated with an R148H mutation of the prion protein gene.

  Authors: Bjarne Krebs, Rosa-Maria Lederer, Otto Windl, Eva-Maria Grasbon-Frodl, Inga Zerr, Hans A Kretzschmar

  Neurogenetics. 06/2005; 6(2):97-100.

• Creutzfeldt-Jakob disease in a patient with an R208H mutation of the prion protein gene (PRNP) and a 17-kDa prion protein fragment.

  Authors: Sigrun Roeber, Bjarne Krebs, Manuela Neumann, Otto Windl, Inga Zerr, Eva-Maria Grasbon-Frodl, Hans A Kretzschmar

  Acta neuropathologica. 05/2005; 109(4):443-8.

  A case of Creutzfeldt-Jakob disease (CJD) with a rare mutation of the prion protein (PrP) gene (PRNP) at codon 208 (R208H) is described. By comparison with two preceding reports, the case describedA case of Creutzfeldt-Jakob disease (CJD) with a rare mutation of the prion protein (PrP) gene (PRNP) at codon 208 (R208H) is described. By comparison with two preceding reports, the case described here displayed two distinct biochemical and neuropathological features. Western blot analysis of brain homogenates showed, in addition to the commonly observed three bands of abnormal protease-resistant PrP isoform (PrP(Sc)), an additional band of about 17 kDa. Neuropathological examination of the post mortem brain revealed tau pathology in the hippocampus and entorhinal cortex, as well as ballooned neurons in the cortex, hippocampus and subcortical gray matter.

• Expression of matrix metalloproteinases and their inhibitors in medulloblastomas and their prognostic relevance.

  Authors: Ozlem Ozen, Bjarne Krebs, Bernhard Hemmerlein, Arnulf Pekrun, Hans Kretzschmar, Jochen Herms

  Clinical cancer research : an official journal of the American Association for Cancer Research. 08/2004; 10(14):4746-53.

  PURPOSE AND EXPERIMENTAL DESIGN: The cellular mechanisms leading to metastatic disease in medulloblastoma (MB), the most common malignant brain tumor in childhood, are mainly unknown. Recently,PURPOSE AND EXPERIMENTAL DESIGN: The cellular mechanisms leading to metastatic disease in medulloblastoma (MB), the most common malignant brain tumor in childhood, are mainly unknown. Recently, however, the involvement of matrix metalloproteinases (MMPs) has been suggested. We examined the expression and localization of four MMPs-MMP-2 and -9, membrane-type 1 and 2 MMP (MT1- and MT2-MMP)-and correlated the data with those for their main inhibitors, tissue inhibitors of metalloproteinases (TIMP-1, -2, and -3), in 83 classical and 18 desmoplastic MBs. RESULTS: Independent of the histological subtype, MMP-2 expression was found in a small percentage of tumors, whereas MMP-9 and MT1- or MT2-MMP were expressed in >75% of tumor samples. The expression of TIMP-1, -2, and -3, on the other hand, was found to depend on the histological subtype: TIMP-3 was often found in classical MB, whereas TIMP-2 was often expressed in desmoplastic MB (P = 0.007-0.001). In addition, both TIMP-3 and -2 correlated significantly with the expression of all studied metalloproteinases except MMP-2. TIMP-1, detected only in classical MB in a low percentage, was the only TIMP that correlated with the expression of MMP-2. Kaplan-Meier estimation revealed significantly reduced long-term survival of patients with strong MMP expression in tumor samples. In multivariate logistic regression analysis, however, the prognosis was significantly determined only by clinical parameters. CONCLUSIONS: TIMP-3 and -2 expression is highly correlated with histological subtypes of MBs and strongly associated with the expression of certain MMPs. The expression of TIMPs and MMPs, however, does not determine prognosis independently of clinical parameters.

• Selenium supplementation in patients with autoimmune thyroiditis decreases thyroid peroxidase antibodies concentrations.

  Authors: Roland Gärtner, Barbara C H Gasnier, Johannes W Dietrich, Bjarne Krebs, Matthias W A Angstwurm

  The Journal of clinical endocrinology and metabolism. 05/2002; 87(4):1687-91.

  In areas with severe selenium deficiency there is a higher incidence of thyroiditis due to a decreased activity of selenium-dependent glutathione peroxidase activity within thyroid cells.In areas with severe selenium deficiency there is a higher incidence of thyroiditis due to a decreased activity of selenium-dependent glutathione peroxidase activity within thyroid cells. Selenium-dependent enzymes also have several modifying effects on the immune system. Therefore, even mild selenium deficiency may contribute to the development and maintenance of autoimmune thyroid diseases. We performed a blinded, placebo-controlled, prospective study in female patients (n = 70; mean age, 47.5 +/- 0.7 yr) with autoimmune thyroiditis and thyroid peroxidase antibodies (TPOAb) and/or Tg antibodies (TgAb) above 350 IU/ml. The primary end point of the study was the change in TPOAb concentrations. Secondary end points were changes in TgAb, TSH, and free thyroid hormone levels as well as ultrasound pattern of the thyroid and quality of life estimation. Patients were randomized into 2 age- and antibody (TPOAb)-matched groups; 36 patients received 200 microg (2.53 micromol) sodium selenite/d, orally, for 3 months, and 34 patients received placebo. All patients were substituted with L-T(4) to maintain TSH within the normal range. TPOAb, TgAb, TSH, and free thyroid hormones were determined by commercial assays. The echogenicity of the thyroid was monitored with high resolution ultrasound. The mean TPOAb concentration decreased significantly to 63.6% (P = 0.013) in the selenium group vs. 88% (P = 0.95) in the placebo group. A subgroup analysis of those patients with TPOAb greater than 1200 IU/ml revealed a mean 40% reduction in the selenium-treated patients compared with a 10% increase in TPOAb in the placebo group. TgAb concentrations were lower in the placebo group at the beginning of the study and significantly further decreased (P = 0.018), but were unchanged in the selenium group. Nine patients in the selenium-treated group had completely normalized antibody concentrations, in contrast to two patients in the placebo group (by chi(2) test, P = 0.01). Ultrasound of the thyroid showed normalized echogenicity in these patients. The mean TSH, free T(4), and free T(3) levels were unchanged in both groups. We conclude that selenium substitution may improve the inflammatory activity in patients with autoimmune thyroiditis, especially in those with high activity. Whether this effect is specific for autoimmune thyroiditis or may also be effective in other endocrine autoimmune diseases has yet to be investigated.

• Activation of phosphatidylinositol 3-kinase by cellular prion protein and its role in cell survival

  Authors: Neville Vassallo, Jochen Herms, Christina Behrens, Bjarne Krebs, Keiichi Saeki, Takashi Onodera, Otto Windl, Hans A. Kretzschmar

  Biochemical and Biophysical Research Communications.

  The cellular prion protein (PrPC) is thought to be involved in protection against cell death, however the exact cellular mechanisms involved are still controversial. Herein we present data thatThe cellular prion protein (PrPC) is thought to be involved in protection against cell death, however the exact cellular mechanisms involved are still controversial. Herein we present data that strongly indicate a functional link between PrPC expression and phosphatidylinositol 3-kinase (PI 3-kinase) activation, a protein kinase that plays a pivotal role in cell survival. Both mouse neuroblastoma N2a cells and immortalized murine hippocampal neuronal cell lines expressing wild-type PrPC had significantly higher PI 3-kinase activity levels than their respective controls. Moreover, PI 3-kinase activity was found to be elevated in brain lysates from wild-type mice, as compared to prion protein-knockout mice. Recruitment of PI 3-kinase by PrPC was shown to contribute to cellular survival toward oxidative stress by using 3-morpholinosydnonimine (SIN-1) and serum deprivation. Moreover, both PI 3-kinase activation and cytoprotection by PrPC appeared to rely on copper binding to the N-terminal octapeptide of PrPC. Thus, we propose a model in which the interaction of copper(II) with the N-terminal domain of PrPC enables transduction of a signal to PI 3-kinase; the latter, in turn, mediates downstream regulation of cell survival.