TY  - JOUR
A1  - Kleikers, Pamela W. M.
A1  - Hooijmans, Carlijn
A1  - Göb, Eva
A1  - Langhauser, Friederike
A1  - Rewell, Sarah S. J.
A1  - Radermacher, Kim
A1  - Ritskes-Hoitinga, Merel
A1  - Howells, David W.
A1  - Kleinschnitz, Christoph
A1  - Schmidt, Harald H. H. W.
T1  - A combined pre-clinical meta-analysis and randomized confirmatory trial approach to improve data validity for therapeutic target validation
JF  - Scientific Reports
N2  - Biomedical research suffers from a dramatically poor translational success. For example, in ischemic stroke, a condition with a high medical need, over a thousand experimental drug targets were unsuccessful. Here, we adopt methods from clinical research for a late-stage pre-clinical meta-analysis (MA) and randomized confirmatory trial (pRCT) approach. A profound body of literature suggests NOX\(_{2}\) to be a major therapeutic target in stroke. Systematic review and MA of all available NOX\(_{2}\)\(^{-/y}\) studies revealed a positive publication bias and lack of statistical power to detect a relevant reduction in infarct size. A fully powered multi-center pRCT rejects NOX\(_{2}\) as a target to improve neurofunctional outcomes or achieve a translationally relevant infarct size reduction. Thus stringent statistical thresholds, reporting negative data and a MA-pRCT approach can ensure biomedical data validity and overcome risks of bias.
KW  - focal cerebral ischemia
KW  - darbepoetin alpha
KW  - mice
KW  - translational stroke research
KW  - colony-stimulating factor
KW  - NADPH oxidase inhibitors
KW  - chronic kidney disease
KW  - diabetes mellitus
KW  - oxidative stress
KW  - search filter
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-151401
VL  - 5
IS  - 13428
ER  - 
TY  - JOUR
A1  - Hoffmann, Linda S
A1  - Schmidt, Peter M
A1  - Keim, Yvonne
A1  - Hoffmann, Carsten
A1  - Schmidt, Harald H H W
A1  - Stasch, Johannes-Peter
T1  - Fluorescence Dequenching Makes Haem-Free Soluble Guanylate Cyclase Detectable in Living Cells
JF  - PLOS ONE
N2  - In cardiovascular disease, the protective NO/sGC/cGMP signalling-pathway is impaired due to a decreased pool of NO-sensitive haem-containing sGC accompanied by a reciprocal increase in NO-insensitive haem-free sGC. However, no direct method to detect cellular haem-free sGC other than its activation by the new therapeutic class of haem mimetics, such as BAY 58-2667, is available. Here we show that fluorescence dequenching, based on the interaction of the optical active prosthetic haem group and the attached biarsenical fluorophor FlAsH can be used to detect changes in cellular sGC haem status. The partly overlap of the emission spectrum of haem and FlAsH allows energy transfer from the fluorophore to the haem which reduces the intensity of FlAsH fluorescence. Loss of the prosthetic group, e. g. by oxidative stress or by replacement with the haem mimetic BAY 58-2667, prevented the energy transfer resulting in increased fluorescence. Haem loss was corroborated by an observed decrease in NO-induced sGC activity, reduced sGC protein levels, and an increased effect of BAY 58-2667. The use of a haem-free sGC mutant and a biarsenical dye that was not quenched by haem as controls further validated that the increase in fluorescence was due to the loss of the prosthetic haem group. The present approach is based on the cellular expression of an engineered sGC variant limiting is applicability to recombinant expression systems. Nevertheless, it allows to monitor sGC's redox regulation in living cells and future enhancements might be able to extend this approach to in vivo conditions.
KW  - spontaneously hypersensitive-rats
KW  - nitric-oxide
KW  - down-regulation
KW  - energy-transfer
KW  - cyclic-gmp
KW  - protein
KW  - activation
KW  - identification
KW  - in-vivo
KW  - no
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-139631
VL  - 6
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  - Radermacher, Kim A.
A1  - Wingler, Kirstin
A1  - Kleikers, Pamela
A1  - Altenhöfer, Sebastian
A1  - Hermans, Johannes J. R.
A1  - Kleinschnitz, Christoph
A1  - Schmidt, Harald H. H. W.
T1  - The 1027th target candidate in stroke: Will NADPH oxidase hold up?
JF  - Experimental and Translational Stroke Medicine
N2  - As recently reviewed, 1026 neuroprotective drug candidates in stroke research have all failed on their road towards validation and clinical translation, reasons being quality issues in preclinical research and publication bias. Quality control guidelines for preclinical stroke studies have now been established. However, sufficient understanding of the underlying mechanisms of neuronal death after stroke that could be possibly translated into new therapies is lacking. One exception is the hypothesis that cellular death is mediated by oxidative stress. Oxidative stress is defined as an excess of reactive oxygen species (ROS) derived from different possible enzymatic sources. Among these, NADPH oxidases (NOX1-5) stand out as they represent the only known enzyme family that has no other function than to produce ROS. Based on data from different NOX knockout mouse models in ischemic stroke, the most relevant isoform appears to be NOX4. Here we discuss the state-of-the-art of this target with respect to stroke and open questions that need to be addressed on the path towards clinical translation.
KW  - NADPH oxidases (NOX)
KW  - stroke therapy
KW  - oxidative stress
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-124197
VL  - 4
IS  - 11
ER  -