TY - JOUR A1 - Schuhmann, Michael K. A1 - Kraft, Peter A1 - Bieber, Michael A1 - Kollikowski, Alexander M. A1 - Schulze, Harald A1 - Nieswandt, Bernhard A1 - Pham, Mirko A1 - Stegner, David A1 - Stoll, Guido T1 - Targeting platelet GPVI plus rt-PA administration but not α2β1-mediated collagen binding protects against ischemic brain damage in mice JF - International Journal of Molecular Science N2 - Platelet collagen interactions at sites of vascular injuries predominantly involve glycoprotein VI (GPVI) and the integrin α2β1. Both proteins are primarily expressed on platelets and megakaryocytes whereas GPVI expression is also shown on endothelial and integrin α2β1 expression on epithelial cells. We recently showed that depletion of GPVI improves stroke outcome without increasing the risk of cerebral hemorrhage. Genetic variants associated with higher platelet surface integrin α2 (ITGA2) receptor levels have frequently been found to correlate with an increased risk of ischemic stroke in patients. However until now, no preclinical stroke study has addressed whether platelet integrin α2β1 contributes to the pathophysiology of ischemia/reperfusion (I/R) injury. Focal cerebral ischemia was induced in C57BL/6 and Itga2\(^{−/−}\) mice by a 60 min transient middle cerebral artery occlusion (tMCAO). Additionally, wild-type animals were pretreated with anti-GPVI antibody (JAQ1) or Fab fragments of a function blocking antibody against integrin α2β1 (LEN/B). In anti-GPVI treated animals, intravenous (IV) recombinant tissue plasminogen activator (rt-PA) treatment was applied immediately prior to reperfusion. Stroke outcome, including infarct size and neurological scoring was determined on day 1 after tMCAO. We demonstrate that targeting the integrin α2β1 (pharmacologic; genetic) did neither reduce stroke size nor improve functional outcome on day 1 after tMCAO. In contrast, depletion of platelet GPVI prior to stroke was safe and effective, even when combined with rt-PA treatment. Our results underscore that GPVI, but not ITGA2, is a promising and safe target in the setting of ischemic stroke. KW - ischemic stroke KW - integrin α2 KW - glycoprotein VI KW - recombinant tissue-type plasminogen activator KW - intracranial bleeding KW - transient middle cerebral artery occlusion Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-201700 SN - 1422-0067 VL - 20 IS - 8 ER - TY - JOUR A1 - Kleinschnitz, Christoph A1 - Grund, Henrike A1 - Wingler, Kirstin A1 - Armitage, Melanie E. A1 - Jones, Emma A1 - Mittal, Manish A1 - Barit, David A1 - Schwarz, Tobias A1 - Geis, Christian A1 - Kraft, Peter A1 - Barthel, Konstanze A1 - Schuhmann, Michael K. A1 - Herrmann, Alexander M. A1 - Meuth, Sven G. A1 - Stoll, Guido A1 - Meurer, Sabine A1 - Schrewe, Anja A1 - Becker, Lore A1 - Gailus-Durner, Valerie A1 - Fuchs, Helmut A1 - Klopstock, Thomas A1 - de Angelis, Martin Hrabe A1 - Jandeleit-Dahm, Karin A1 - Shah, Ajay M. A1 - Weissmann, Norbert A1 - Schmidt, Harald H. H. W. T1 - Post-Stroke Inhibition of Induced NADPH Oxidase Type 4 Prevents Oxidative Stress and Neurodegeneration N2 - 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. KW - Schlaganfall Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68416 ER - TY - JOUR A1 - Essig, Fabian A1 - Kollikowski, Alexander M. A1 - Pham, Mirko A1 - Solymosi, László A1 - Stoll, Guido A1 - Haeusler, Karl Georg A1 - Kraft, Peter A1 - Schuhmann, Michael K. T1 - Immunohistological analysis of neutrophils and neutrophil extracellular traps in human thrombemboli causing acute ischemic stroke JF - International Journal of Molecular Sciences N2 - Ischemic stroke caused by thromboembolic occlusion of large cerebral arteries, such as the internal carotid (ICA) and/or the middle cerebral artery (MCA), is treated by mechanical thrombectomy (MT). MT allows salvage of the vessel-occluding thrombemboli, which most frequently originate from the left atrium or the left ventricle of the heart or from sites of plaque rupture within large arteries above the heart. Clot composition may influence the efficacy of (intravenous) thrombolysis and MT, respectively. We analyzed 37 human thrombemboli obtained from acute ischemic stroke patients during MT with special emphasis on histological staining of neutrophils and neutrophil extracellular traps (NETs). We found neutrophils as the main cellular component of cerebral thrombemboli but encountered considerable morphological heterogeneity. Neutrophils accumulated in the border region of fibrin-rich structures indicating possible interaction of neutrophils with distinct structural thrombembolus components. Web-like NETs were found in 35 of 37 thrombemboli in varying amounts. NETs were almost exclusively found within fibrin-rich areas. Importantly, stroke etiology, age and present oral anticoagulation was associated with morphological patterns and the amount of neutrophils. Correlation of histological data and imaging data revealed that relative Hounsfield units of cerebral thrombemboli positively correlated with the amount of red blood cells. In summary, our results demonstrate that neutrophils and NETs are substantial constituents of cerebral thrombemboli and contribute to their structural complexity. KW - acute ischemic stroke KW - thrombemboli KW - neutrophils KW - NETs KW - immunohistochemistry Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-236192 SN - 1422-0067 VL - 21 IS - 19 ER - TY - JOUR A1 - Essig, Fabian A1 - Babilon, Lilith A1 - Vollmuth, Christoph A1 - Kollikowski, Alexander M. A1 - Pham, Mirko A1 - Solymosi, László A1 - Haeusler, Karl Georg A1 - Kraft, Peter A1 - Stoll, Guido A1 - Schuhmann, Michael K. T1 - High mobility group box 1 protein in cerebral thromboemboli JF - International Journal of Molecular Sciences N2 - High-mobility group box 1 protein (HMGB1) is a damage-associated molecular pattern (DAMP) involved in neutrophil extracellular trap (NET) formation and thrombosis. NETs are regularly found in cerebral thromboemboli. We here analyzed associated HMGB1 expression in human thromboemboli retrieved via mechanical thrombectomy from 37 stroke patients with large vessel occlusion. HMGB1 was detected in all thromboemboli, accounting for 1.7% (IQR 0.6–6.2%) of the total thromboemboli area and was found to be colocalized with neutrophils and NETs and in spatial proximity to platelets. Correlation analysis revealed that the detection of HMGB1 was strongly related to the number of neutrophils (r = 0.58, p = 0.0002) and platelets (r = 0.51, p = 0.001). Our results demonstrate that HMGB1 is a substantial constituent of thromboemboli causing large vessel occlusion stroke. KW - acute ischemic stroke KW - thromboemboli KW - HMGB1 KW - neutrophils KW - platelets KW - immunohistochemistry Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-265568 SN - 1422-0067 VL - 22 IS - 20 ER - TY - JOUR A1 - Göbel, Kerstin A1 - Pankratz, Susann A1 - Asaridou, Chloi-Magdalini A1 - Herrmann, Alexander M. A1 - Bittner, Stefan A1 - Merker, Monika A1 - Ruck, Tobias A1 - Glumm, Sarah A1 - Langhauser, Friederike A1 - Kraft, Peter A1 - Krug, Thorsten F. A1 - Breuer, Johanna A1 - Herold, Martin A1 - Gross, Catharina C. A1 - Beckmann, Denise A1 - Korb-Pap, Adelheid A1 - Schuhmann, Michael K. A1 - Kuerten, Stefanie A1 - Mitroulis, Ioannis A1 - Ruppert, Clemens A1 - Nolte, Marc W. A1 - Panousis, Con A1 - Klotz, Luisa A1 - Kehrel, Beate A1 - Korn, Thomas A1 - Langer, Harald F. A1 - Pap, Thomas A1 - Nieswandt, Bernhard A1 - Wiendl, Heinz A1 - Chavakis, Triantafyllos A1 - Kleinschnitz, Christoph A1 - Meuth, Sven G. T1 - Blood coagulation factor XII drives adaptive immunity during neuroinflammation via CD87-mediated modulation of dendritic cells JF - Nature Communications N2 - 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. KW - blood coagulation KW - factor XII KW - neuroinflammation KW - dendric cells Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-165503 VL - 7 IS - 11626 ER -