@article{HoppAlbertWeissenbergerMencletal.2016, author = {Hopp, Sarah and Albert-Weissenberger, Christiane and Mencl, Stine and Bieber, Michael and Schuhmann, Michael K. and Stetter, Christian and Nieswandt, Bernhard and Schmidt, Peter M. and Monoranu, Camelia-Maria and Alafuzoff, Irina and Marklund, Niklas and Nolte, Marc W. and Sir{\´e}n, Anna-Leena and Kleinschnitz, Christoph}, title = {Targeting coagulation factor XII as a novel therapeutic option in brain trauma}, series = {Annals of Neurology}, volume = {79}, journal = {Annals of Neurology}, number = {6}, doi = {10.1002/ana.24655}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-188800}, pages = {970-982}, year = {2016}, abstract = {Objective: Traumatic brain injury is a major global public health problem for which specific therapeutic interventions are lacking. There is, therefore, a pressing need to identify innovative pathomechanism-based effective therapies for this condition. Thrombus formation in the cerebral microcirculation has been proposed to contribute to secondary brain damage by causing pericontusional ischemia, but previous studies have failed to harness this finding for therapeutic use. The aim of this study was to obtain preclinical evidence supporting the hypothesis that targeting factor XII prevents thrombus formation and has a beneficial effect on outcome after traumatic brain injury. Methods: We investigated the impact of genetic deficiency of factor XII and acute inhibition of activated factor XII with a single bolus injection of recombinant human albumin-fused infestin-4 (rHA-Infestin-4) on trauma-induced microvascular thrombus formation and the subsequent outcome in 2 mouse models of traumatic brain injury. Results: Our study showed that both genetic deficiency of factor XII and an inhibition of activated factor XII in mice minimize trauma-induced microvascular thrombus formation and improve outcome, as reflected by better motor function, reduced brain lesion volume, and diminished neurodegeneration. Administration of human factor XII in factor XII-deficient mice fully restored injury-induced microvascular thrombus formation and brain damage. Interpretation: The robust protective effect of rHA-Infestin-4 points to a novel treatment option that can decrease ischemic injury after traumatic brain injury without increasing bleeding tendencies.}, language = {en} } @article{KleinschnitzGrundWingleretal.2010, author = {Kleinschnitz, Christoph and Grund, Henrike and Wingler, Kirstin and Armitage, Melanie E. and Jones, Emma and Mittal, Manish and Barit, David and Schwarz, Tobias and Geis, Christian and Kraft, Peter and Barthel, Konstanze and Schuhmann, Michael K. and Herrmann, Alexander M. and Meuth, Sven G. and Stoll, Guido and Meurer, Sabine and Schrewe, Anja and Becker, Lore and Gailus-Durner, Valerie and Fuchs, Helmut and Klopstock, Thomas and de Angelis, Martin Hrabe and Jandeleit-Dahm, Karin and Shah, Ajay M. and Weissmann, Norbert and Schmidt, Harald H. H. W.}, title = {Post-Stroke Inhibition of Induced NADPH Oxidase Type 4 Prevents Oxidative Stress and Neurodegeneration}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68416}, year = {2010}, abstract = {Ischemic stroke is the second leading cause of death worldwide. Only one moderately effective therapy exists, albeit with contraindications that exclude 90\% of the patients. This medical need contrasts with a high failure rate of more than 1,000 pre-clinical drug candidates for stroke therapies. Thus, there is a need for translatable mechanisms of neuroprotection and more rigid thresholds of relevance in pre-clinical stroke models. One such candidate mechanism is oxidative stress. However, antioxidant approaches have failed in clinical trials, and the significant sources of oxidative stress in stroke are unknown. We here identify NADPH oxidase type 4 (NOX4) as a major source of oxidative stress and an effective therapeutic target in acute stroke. Upon ischemia, NOX4 was induced in human and mouse brain. Mice deficient in NOX4 (Nox42/2) of either sex, but not those deficient for NOX1 or NOX2, were largely protected from oxidative stress, blood-brain-barrier leakage, and neuronal apoptosis, after both transient and permanent cerebral ischemia. This effect was independent of age, as elderly mice were equally protected. Restoration of oxidative stress reversed the stroke-protective phenotype in Nox42/2 mice. Application of the only validated low-molecular-weight pharmacological NADPH oxidase inhibitor, VAS2870, several hours after ischemia was as protective as deleting NOX4. The extent of neuroprotection was exceptional, resulting in significantly improved long-term neurological functions and reduced mortality. NOX4 therefore represents a major source of oxidative stress and novel class of drug target for stroke therapy.}, subject = {Schlaganfall}, language = {en} } @article{RolfesRuckDavidetal.2022, author = {Rolfes, Leoni and Ruck, Tobias and David, Christina and Mencl, Stine and Bock, Stefanie and Schmidt, Mariella and Strecker, Jan-Kolja and Pfeuffer, Steffen and Mecklenbeck, Andreas-Schulte and Gross, Catharina and Gliem, Michael and Minnerup, Jens and Schuhmann, Michael K. and Kleinschnitz, Christoph and Meuth, Sven G.}, title = {Natural Killer Cells Are Present in Rag1\(^{-/-}\) Mice and Promote Tissue Damage During the Acute Phase of Ischemic Stroke}, series = {Translational Stroke Research}, volume = {13}, journal = {Translational Stroke Research}, number = {1}, issn = {1868-4483}, doi = {10.1007/s12975-021-00923-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-308924}, pages = {197-211}, year = {2022}, abstract = {Rag1\(^{-/-}\) mice, lacking functional B and T cells, have been extensively used as an adoptive transfer model to evaluate neuroinflammation in stroke research. However, it remains unknown whether natural killer (NK) cell development and functions are altered in Rag1\(^{-/-}\) mice as well. This connection has been rarely discussed in previous studies but might have important implications for data interpretation. In contrast, the NOD-Rag1\(^{null}\)IL2rg\(^{null}\) (NRG) mouse model is devoid of NK cells and might therefore eliminate this potential shortcoming. Here, we compare immune-cell frequencies as well as phenotype and effector functions of NK cells in Rag1\(^{-/-}\) and wildtype (WT) mice using flow cytometry and functional in vitro assays. Further, we investigate the effect of Rag1\(^{-/-}\) NK cells in the transient middle cerebral artery occlusion (tMCAO) model using antibody-mediated depletion of NK cells and adoptive transfer to NRG mice in vivo. NK cells in Rag1\(^{-/-}\) were comparable in number and function to those in WT mice. Rag1\(^{-/-}\) mice treated with an anti-NK1.1 antibody developed significantly smaller infarctions and improved behavioral scores. Correspondingly, NRG mice supplemented with NK cells were more susceptible to tMCAO, developing infarctions and neurological deficits similar to Rag1-/- controls. Our results indicate that NK cells from Rag1-/- mice are fully functional and should therefore be considered in the interpretation of immune-cell transfer models in experimental stroke. Fortunately, we identified the NRG mice, as a potentially better-suited transfer model to characterize individual cell subset-mediated neuroinflammation in stroke.}, language = {en} } @article{SchuhmannGunrebenKleinschnitzetal.2016, author = {Schuhmann, Michael K. and Gunreben, Ignaz and Kleinschnitz, Christoph and Kraft, Peter}, title = {Immunohistochemical Analysis of Cerebral Thrombi Retrieved by Mechanical Thrombectomy from Patients with Acute Ischemic Stroke}, series = {International Journal of Molecular Sciences}, volume = {17}, journal = {International Journal of Molecular Sciences}, number = {3}, doi = {10.3390/ijms17030298}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-166206}, pages = {298}, year = {2016}, abstract = {Mechanical thrombectomy is a novel treatment option for patients with acute ischemic stroke (AIS). Only a few studies have previously suggested strategies to categorize retrieved clots according to their histologic composition. However, these reports did not analyze potential biomarkers that are of importance in stroke-related inflammation. We therefore histopathologically investigated 37 intracerebral thrombi mechanically retrieved from patients with AIS, and focused on the composition of immune cells and platelets. We also conducted correlation analyses of distinctive morphologic patterns (erythrocytic, serpentine, layered, red, white, mixed appearance) with clinical parameters. Most T cells and monocytes were detected in erythrocytic and red clots, in which the distribution of these cells was random. In contrast, von Willebrand factor (vWF)-positive areas co-localized with regions of fibrin and collagen. While clots with huge amounts of vWF seem to be associated with a high National Institute of Health Stroke Scale score at admission, histologic findings could not predict the clinical outcome at discharge. In summary, we provide the first histologic description of mechanically retrieved intracerebral thrombi regarding biomarkers relevant for inflammation in ischemic stroke.}, language = {en} } @article{KraftSchuhmannGarzetal.2017, author = {Kraft, Peter and Schuhmann, Michael K. and Garz, Cornelia and Jandke, Solveig and Urlaub, Daniela and Mencl, Stine and Zernecke, Alma and Heinze, Hans-Jochen and Carare, Roxana O. and Kleinschnitz, Christoph and Schreiber, Stefanie}, title = {Hypercholesterolemia induced cerebral small vessel disease}, series = {PLoS ONE}, volume = {12}, journal = {PLoS ONE}, number = {8}, doi = {10.1371/journal.pone.0182822}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170493}, pages = {e0182822}, year = {2017}, abstract = {Background While hypercholesterolemia plays a causative role for the development of ischemic stroke in large vessels, its significance for cerebral small vessel disease (CSVD) remains unclear. We thus aimed to understand the detailed relationship between hypercholesterolemia and CSVD using the well described Ldlr\(^{-/-}\) mouse model. Methods We used Ldlr\(^{-/-}\) mice (n = 16) and wild-type (WT) mice (n = 15) at the age of 6 and 12 months. Ldlr\(^{-/-}\) mice develop high plasma cholesterol levels following a high fat diet. We analyzed cerebral capillaries and arterioles for intravascular erythrocyte accumulations, thrombotic vessel occlusions, blood-brain barrier (BBB) dysfunction and microbleeds. Results We found a significant increase in the number of erythrocyte stases in 6 months old Ldlr\(^{-/-}\) mice compared to all other groups (P < 0.05). Ldlr\(^{-/-}\) animals aged 12 months showed the highest number of thrombotic occlusions while in WT animals hardly any occlusions could be observed (P < 0.001). Compared to WT mice, Ldlr\(^{-/-}\) mice did not display significant gray matter BBB breakdown. Microhemorrhages were observed in one Ldlr\(^{-/-}\) mouse that was 6 months old. Results did not differ when considering subcortical and cortical regions. Conclusions In Ldlr\(^{-/-}\) mice, hypercholesterolemia is related to a thrombotic CSVD phenotype, which is different from hypertension-related CSVD that associates with a hemorrhagic CSVD phenotype. Our data demonstrate a relationship between hypercholesterolemia and the development of CSVD. Ldlr\(^{-/-}\) mice appear to be an adequate animal model for research into CSVD.}, language = {en} } @article{SchuhmannBittnerMeuthetal.2015, author = {Schuhmann, Michael K. and Bittner, Stefan and Meuth, Sven G. and Kleinschnitz, Christoph and Fluri, Felix}, title = {Fingolimod (FTY720-P) does not stabilize the blood-brain barrier under inflammatory conditions in an in vitro model}, series = {International Journal of Molecular Sciences}, volume = {16}, journal = {International Journal of Molecular Sciences}, doi = {10.3390/ijms161226177}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-145047}, pages = {29454-29466}, year = {2015}, abstract = {Breakdown of the blood-brain barrier (BBB) is an early hallmark of multiple sclerosis (MS), a progressive inflammatory disease of the central nervous system. Cell adhesion in the BBB is modulated by sphingosine-1-phosphate (S1P), a signaling protein, via S1P receptors (S1P\(_1\)). Fingolimod phosphate (FTY720-P) a functional S1P\(_1\) antagonist has been shown to improve the relapse rate in relapsing-remitting MS by preventing the egress of lymphocytes from lymph nodes. However, its role in modulating BBB permeabilityin particular, on the tight junction proteins occludin, claudin 5 and ZO-1has not been well elucidated to date. In the present study, FTY720-P did not change the transendothelial electrical resistance in a rat brain microvascular endothelial cell (RBMEC) culture exposed to inflammatory conditions and thus did not decrease endothelial barrier permeability. In contrast, occludin was reduced in RBMEC culture after adding FTY720-P. Additionally, FTY720-P did not alter the amount of endothelial matrix metalloproteinase (MMP)-9 and MMP-2 in RBMEC cultures. Taken together, our observations support the assumption that S1P\(_1\) plays a dual role in vascular permeability, depending on its ligand. Thus, S1P\(_1\) provides a mechanistic basis for FTY720-P-associated disruption of endothelial barrierssuch as the blood-retinal barrierwhich might result in macular edema.}, language = {en} } @article{SchuhmannLanghauserZimmermannetal.2023, author = {Schuhmann, Michael K. and Langhauser, Friederike and Zimmermann, Lena and Bellut, Maximilian and Kleinschnitz, Christoph and Fluri, Felix}, title = {Dimethyl fumarate attenuates lymphocyte infiltration and reduces infarct size in experimental stroke}, series = {International journal of molecular sciences}, volume = {24}, journal = {International journal of molecular sciences}, number = {21}, doi = {10.3390/ijms242115540}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357731}, year = {2023}, abstract = {Ischemic stroke is associated with exacerbated tissue damage caused by the activation of immune cells and the initiation of other inflammatory processes. Dimethyl fumarate (DMF) is known to modulate the immune response, activate antioxidative pathways, and improve the blood-brain barrier (BBB) after stroke. However, the specific impact of DMF on immune cells after cerebral ischemia remains unclear. In our study, male mice underwent transient middle cerebral artery occlusion (tMCAO) for 30 min and received oral DMF (15 mg/kg) or a vehicle immediately after tMCAO, followed by twice-daily administrations for 7 days. Infarct volume was assessed on T2-weighted magnetic resonance images on days 1 and 7 after tMCAO. Brain-infiltrating immune cells (lymphocytes, monocytes) and microglia were quantified using fluorescence-activated cell sorting. DMF treatment significantly reduced infarct volumes and brain edema. On day 1 after tMCAO, DMF-treated mice showed reduced lymphocyte infiltration compared to controls, which was not observed on day 7. Monocyte and microglial cell counts did not differ between groups on either day. In the acute phase of stroke, DMF administration attenuated lymphocyte infiltration, probably due to its stabilizing effect on the BBB. This highlights the potential of DMF as a therapeutic candidate for mitigating immune cell-driven damage in stroke.}, language = {en} } @article{KraftDrechslerSchuhmannetal.2015, author = {Kraft, Peter and Drechsler, Christiane and Schuhmann, Michael K. and Gunreben, Ignaz and Kleinschnitz, Christoph}, title = {Characterization of Peripheral Immune Cell Subsets in Patients with Acute and Chronic Cerebrovascular Disease: A Case-Control Study}, series = {International Journal of Molecular Science}, volume = {16}, journal = {International Journal of Molecular Science}, number = {10}, doi = {10.3390/ijms161025433}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-126319}, pages = {25433-25449}, year = {2015}, abstract = {Immune cells (IC) play a crucial role in murine stroke pathophysiology. However, data are limited on the role of these cells in ischemic stroke in humans. We therefore aimed to characterize and compare peripheral IC subsets in patients with acute ischemic stroke/transient ischemic attack (AIS/TIA), chronic cerebrovascular disease (CCD) and healthy volunteers (HV). We conducted a case-control study of patients with AIS/TIA (n = 116) or CCD (n = 117), and HV (n = 104) who were enrolled at the University Hospital W{\"u}rzburg from 2010 to 2013. We determined the expression and quantity of IC subsets in the three study groups and performed correlation analyses with demographic and clinical parameters. The quantity of several IC subsets differed between the AIS/TIA, CCD, and HV groups. Several clinical and demographic variables independently predicted the quantity of IC subsets in patients with AIS/TIA. No significant changes in the quantity of IC subsets occurred within the first three days after AIS/TIA. Overall, these findings strengthen the evidence for a pathophysiologic role of IC in human ischemic stroke and the potential use of IC-based biomarkers for the prediction of stroke risk. A comprehensive description of IC kinetics is crucial to enable the design of targeted treatment strategies.}, language = {en} } @article{AlbertWeissenbergerMenclSchuhmannetal.2014, author = {Albert-Weissenberger, Christiane and Mencl, Stine and Schuhmann, Michael K. and Salur, Irmak and G{\"o}b, Eva and Langhauser, Friederike and Hopp, Sarah and Hennig, Nelli and Meuth, Sven G. and Nolte, Marc W. and Sir{\´e}n, Anna-Leena and Kleinschnitz, Christoph}, title = {C1-Inhibitor protects from focal brain trauma in a cortical cryolesion mice model by reducing thrombo-inflammation}, series = {Frontiers in Cellular Neuroscience}, volume = {8}, journal = {Frontiers in Cellular Neuroscience}, issn = {1662-5102}, doi = {10.3389/fncel.2014.00269}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-119263}, pages = {269}, year = {2014}, abstract = {Traumatic brain injury (TBI) induces a strong inflammatory response which includes blood-brain barrier damage, edema formation and infiltration of different immune cell subsets. More recently, microvascular thrombosis has been identified as another pathophysiological feature of TBI. The contact-kinin system represents an interface between inflammatory and thrombotic circuits and is activated in different neurological diseases. C1-Inhibitor counteracts activation of the contact-kinin system at multiple levels. We investigated the therapeutic potential of C1-Inhibitor in a model of TBI. Male and female C57BL/6 mice were subjected to cortical cryolesion and treated with C1-Inhibitor after 1 h. Lesion volumes were assessed between day 1 and day 5 and blood-brain barrier damage, thrombus formation as well as the local inflammatory response were determined post TBI. Treatment of male mice with 15.0 IU C1-Inhibitor, but not 7.5 IU, 1 h after cryolesion reduced lesion volumes by ~75\% on day 1. This protective effect was preserved in female mice and at later stages of trauma. Mechanistically, C1-Inhibitor stabilized the blood-brain barrier and decreased the invasion of immune cells into the brain parenchyma. Moreover, C1-Inhibitor had strong antithrombotic effects. C1-Inhibitor represents a multifaceted anti-inflammatory and antithrombotic compound that prevents traumatic neurodegeneration in clinically meaningful settings.}, language = {en} } @article{GoebelPankratzAsaridouetal.2016, author = {G{\"o}bel, Kerstin and Pankratz, Susann and Asaridou, Chloi-Magdalini and Herrmann, Alexander M. and Bittner, Stefan and Merker, Monika and Ruck, Tobias and Glumm, Sarah and Langhauser, Friederike and Kraft, Peter and Krug, Thorsten F. and Breuer, Johanna and Herold, Martin and Gross, Catharina C. and Beckmann, Denise and Korb-Pap, Adelheid and Schuhmann, Michael K. and Kuerten, Stefanie and Mitroulis, Ioannis and Ruppert, Clemens and Nolte, Marc W. and Panousis, Con and Klotz, Luisa and Kehrel, Beate and Korn, Thomas and Langer, Harald F. and Pap, Thomas and Nieswandt, Bernhard and Wiendl, Heinz and Chavakis, Triantafyllos and Kleinschnitz, Christoph and Meuth, Sven G.}, title = {Blood coagulation factor XII drives adaptive immunity during neuroinflammation via CD87-mediated modulation of dendritic cells}, series = {Nature Communications}, volume = {7}, journal = {Nature Communications}, number = {11626}, doi = {10.1038/ncomms11626}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-165503}, year = {2016}, abstract = {Aberrant immune responses represent the underlying cause of central nervous system (CNS) autoimmunity, including multiple sclerosis (MS). Recent evidence implicated the crosstalk between coagulation and immunity in CNS autoimmunity. Here we identify coagulation factor XII (FXII), the initiator of the intrinsic coagulation cascade and the kallikrein-kinin system, as a specific immune cell modulator. High levels of FXII activity are present in the plasma of MS patients during relapse. Deficiency or pharmacologic blockade of FXII renders mice less susceptible to experimental autoimmune encephalomyelitis (a model of MS) and is accompanied by reduced numbers of interleukin-17A-producing T cells. Immune activation by FXII is mediated by dendritic cells in a CD87-dependent manner and involves alterations in intracellular cyclic AMP formation. Our study demonstrates that a member of the plasmatic coagulation cascade is a key mediator of autoimmunity. FXII inhibition may provide a strategy to combat MS and other immune-related disorders.}, language = {en} }