Kirstin Wingler

Publications of Kirstin Wingler

• Diagnosis and individual treatment of cardiovascular diseases: targeting vascular oxidative stress.

  Authors: Melanie E Armitage, Mylinh La, Harald Hhw Schmidt, Kirstin Wingler

  Expert review of clinical pharmacology. 09/2010; 3(5):639-48.

  Cardiovascular diseases are the leading cause of death and disability worldwide, yet we do not fully understand their underlying causes to reliably identify and treat, let alone prevent, theseCardiovascular diseases are the leading cause of death and disability worldwide, yet we do not fully understand their underlying causes to reliably identify and treat, let alone prevent, these diseases. The majority of therapeutic approaches are symptom orientated, and current practice often follows a 'one-fits-all' approach. New strategies are needed, which harness the potential of individualized medicine with its three major pillars: in vitro diagnostics for early identification of individuals at risk and monitoring of drug efficacy; molecular imaging for disease localization and monitoring; and innovative, mechanism-based drugs. One so far untargeted mechanism of cardiovascular disease is oxidative stress, that is, the increased occurrence of reactive oxygen species in the vascular wall that leads to endothelial dysfunction. We outline why previous antioxidant supplements do not work and suggest an alternative approach targeting the enzymatic sources of oxidative stress and using emerging biomarkers of oxidative stress. These and similar approaches may be applied to fewer patients but in a much more individualized, effective and cost-saving manner.

• Oxidative stress and endothelial dysfunction in aortas of aged spontaneously hypertensive rats by NOX1/2 is reversed by NADPH oxidase inhibition.

  Authors: Sven Wind, Knut Beuerlein, Melanie E Armitage, Ashraf Taye, Arun H S Kumar, Daniel Janowitz, Christina Neff, Ajay M Shah, Kirstin Wingler, Harald H H W Schmidt

  Hypertension. 09/2010; 56(3):490-7.

  Arterial hypertension is associated with increased levels of reactive oxygen species, which may scavenge endothelium-derived NO and thereby diminish its vasorelaxant effects. However, theArterial hypertension is associated with increased levels of reactive oxygen species, which may scavenge endothelium-derived NO and thereby diminish its vasorelaxant effects. However, the quantitatively relevant source of reactive oxygen species is unclear. Thus, this potential pathomechanism is not yet pharmacologically targetable. Several enzymatic sources of reactive oxygen species have been suggested: uncoupled endothelial NO synthase, xanthine oxidase, and NADPH oxidases. Here we show that increased reactive oxygen species formation in aortas of 12- to 14-month-old spontaneously hypertensive rats versus age-matched Wistar Kyoto rats is inhibited by the specific NADPH oxidase inhibitor VAS2870 but neither by the xanthine oxidase inhibitor oxypurinol nor the NO synthase inhibitor N(G)-nitro-l-arginine methyl ester. NADPH oxidase activity, as well as protein expression of its catalytic subunits, NOX1 and NOX2, was increased in the aortas of spontaneously hypertensive rats, whereas the expression of NOX4 protein, the most abundant NOX isoform, was not significantly changed. Impaired acetylcholine-induced relaxation of spontaneously hypertensive rat aortas was significantly improved by VAS2870. In conclusion, NOX1 and NOX2 but not NOX4 proteins are increased in aged spontaneously hypertensive rat aortas. Importantly, these NOX isoforms, in particular, ectopic expression of NOX1 in endothelial cells, appear to affect vascular function in an NADPH oxidase inhibitor-reversible manner. NADPH oxidases may, thus, be a novel target for the treatment of systemic hypertension.

• Post-stroke inhibition of induced NADPH oxidase type 4 prevents oxidative stress and neurodegeneration.

  Authors: Christoph Kleinschnitz, Henrike Grund, Kirstin Wingler, Melanie E Armitage, Emma Jones, Manish Mittal, David Barit, Tobias Schwarz, Christian Geis, Peter Kraft [......] Anja Schrewe, Lore Becker, Valérie Gailus-Durner, Helmut Fuchs, Thomas Klopstock, Martin Hrabé de Angelis, Karin Jandeleit-Dahm, Ajay M Shah, Norbert Weissmann, Harald H H W Schmidt

  PLoS biology. 01/2010; 8(9).

  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 needIschemic 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 (Nox4(-/-)) 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 Nox4(-/-) 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.

• Good stress, bad stress-the delicate balance in the vasculature.

  Authors: Kirstin Wingler, Harald H H W Schmidt

  Deutsches Ärzteblatt international. 10/2009; 106(42):677-84.

  BACKGROUND: Radicals have important physiological functions, for example, in immune defense and vasoprotection. However, they are also potentially dangerous waste products of cellular metabolism andBACKGROUND: Radicals have important physiological functions, for example, in immune defense and vasoprotection. However, they are also potentially dangerous waste products of cellular metabolism and they can contribute to the development of many different diseases. METHOD: Selective literature review. RESULTS: The scientific understanding of radicals has not yet led to any therapeutic application. For many years, scavenging already formed radicals with antioxidants was considered to be the most promising therapeutic approach, but clinical trials based on this principle have yielded mostly negative results. Thus, entirely new approaches are needed. The goal should be to prevent the formation of harmful radicals, or to treat radical-related damage if it has already occurred. New diagnostic tools have the potential to identify those patients that are most likely to benefit from this form of treatment, as well as to document its success. CONCLUSIONS: A new generation of cardiovascular drugs is being developed for the prevention or the mechanism-based treatment of vascular damage caused by oxidative stress. This new therapy should go hand in hand with new diagnostics, in accordance with the principle of individualized medicine.

• Translating the oxidative stress hypothesis into the clinic: NOX versus NOS.

  Authors: Melanie Armitage, Kirstin Wingler, Harald Schmidt, Mylinh La

  Journal of molecular medicine (Berlin, Germany). 10/2009;

  Cardiovascular diseases remain the leading cause of death in industrialised nations. Since the pathomechanisms of most cardiovascular diseases are not understood, the majority of therapeuticCardiovascular diseases remain the leading cause of death in industrialised nations. Since the pathomechanisms of most cardiovascular diseases are not understood, the majority of therapeutic approaches are symptom-orientated. Knowing the molecular mechanism of disease would enable more targeted therapies. One postulated underlying mechanism of cardiovascular diseases is oxidative stress, i.e. the increased occurrence of reactive oxygen species such as superoxide. Oxidative stress leads to a dysfunction of vascular endothelium-dependent protective mechanisms. There is growing evidence that this scenario also involves impaired nitric oxide (NO)-cyclic GMP signalling. Out of a number of enzyme families that can produce reactive oxygen species, NADPH oxidases stand out, as they are the only enzymes whose sole purpose is to produce reactive oxygen species. This review focuses on the clinically validated targets of oxidative stress, NO synthase (NOS) and the NO receptor, soluble guanylate cyclase as well as the source of ROS, e.g. NADPH oxidases. We place recent knowledge in the function and regulation of these enzyme families into clinical perspective. For a comprehensive overview of the biology and pharmacology of oxidative stress and possible other sources and targets, we refer to other literature overviews.

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• NADPH oxidases in the vasculature: Molecular features, roles in disease and pharmacological inhibition.

  Authors: Stavros Selemidis, Christopher G Sobey, Harald H H W Schmidt, Kirstin Wingler, Grant R Drummond

  Pharmacology & therapeutics. 09/2008;

  Until the 1970s, reactive oxygen species (ROS) were considered merely harmful by-products of aerobic respiration and the driving force behind the evolution of an array of cellular antioxidant enzymesUntil the 1970s, reactive oxygen species (ROS) were considered merely harmful by-products of aerobic respiration and the driving force behind the evolution of an array of cellular antioxidant enzymes with the purpose of rapidly metabolising ROS to minimise their oxidising effects. However, the perception that ROS are only harmful to cells has since been questioned by a burgeoning body of evidence pointing to the existence of enzymes with the dedicated function of generating ROS. NADPH oxidases represent the only known family of enzymes whose sole purpose is to generate ROS. Members of this enzyme family are expressed across mammalian and non-mammalian cells, and influence a multitude of biological functions including host defence and redox signalling. However, although ROS are deliberately generated by NADPH oxidases during normal cell physiology, the observations that their expression and activity is markedly upregulated in the blood vessel wall in a number of cardiovascular 'high-risk' states (e.g. hypertension, hypercholesterolemia) implicates them in the oxidative stress that gives rise to artery disease and ultimately heart attacks and strokes. These observations highlight the fact that NADPH oxidases are important therapeutic targets in cardiovascular disease and that, hence, there is clearly a need for the development of selective inhibitors of these enzymes. Here we highlight the structural and biochemical characteristics of the NADPH oxidase family and then comprehensively review the literature on the currently available pharmacological inhibitors of these enzymes with a particular emphasis on their mechanisms of action, isoform selectivity and therapeutic potential in cardiovascular disease.

• Novel Nox inhibitor of oxLDL-induced reactive oxygen species formation in human endothelial cells.

  Authors: Claudia Stielow, Rusan A Catar, Gregor Muller, Kirstin Wingler, Peter Scheurer, Harald H H W Schmidt, Henning Morawietz

  Biochemical and biophysical research communications. 05/2006; 344(1):200-5.

  In this study, we investigated effects of a novel NAD(P)H oxidase (Nox)-inhibitor 3-benzyl-7-(2-benzoxazolyl)thio-1,2,3-triazolo[4,5-d]pyrimidine (VAS2870) on oxidized low-density lipoproteinIn this study, we investigated effects of a novel NAD(P)H oxidase (Nox)-inhibitor 3-benzyl-7-(2-benzoxazolyl)thio-1,2,3-triazolo[4,5-d]pyrimidine (VAS2870) on oxidized low-density lipoprotein (oxLDL)-mediated reactive oxygen species (ROS) formation in human endothelial cells. Primary cultures of human umbilical vein endothelial cells were cultured to confluence and ROS formation was induced with 50microg/ml oxLDL for 2h. ROS formation was detected by chemiluminescence (CL) using the Diogenes reagent. OxLDL induced ROS formation in human endothelial cells (171+/-12%; n=10, P<0.05 vs. control). This augmented ROS formation in response to oxLDL was completely inhibited by the Nox inhibitor VAS2870 (101+/-9%; n=7, P<0.05 vs. oxLDL). Similar results were obtained with superoxide dismutase (91+/-7%; n=7, P<0.05 vs. oxLDL). However, the Nox4 mRNA expression level was neither changed by oxLDL nor VAS2870. We conclude that VAS2870 could provide a novel strategy to inhibit the augmented endothelial superoxide anion formation in response to cardiovascular risk factors.

• [L-arginine. A key substance for dietetic therapy in arteriosclerosis?]

  Authors: Kirstin Wingler, Harald Schmidt

  Medizinische Monatsschrift für Pharmazeuten. 04/2005; 28(3):97-103.

• A constitutive NADPH oxidase-like system containing gp91phox homologs in human keratinocytes.

  Authors: Walee Chamulitrat, Wolfgang Stremmel, Tsukasa Kawahara, Kazuhito Rokutan, Hirotada Fujii, Kirstin Wingler, Harald H H W Schmidt, Rainer Schmidt

  The Journal of investigative dermatology. 05/2004; 122(4):1000-9.

  In non-phagocytic cells, superoxide has been implicated in physiological and pathological cellular functions in the skin and mucosa, such as, host defense, mitogenic responses, and malignantIn non-phagocytic cells, superoxide has been implicated in physiological and pathological cellular functions in the skin and mucosa, such as, host defense, mitogenic responses, and malignant conversion. Here, we identify a constitutively expressed heme-flavoprotein NADPH oxidase (Nox) system as a source of superoxide in human skin (HaCaT) and gingival mucosal (GM16) keratinocyte cell lines. Western blot analysis showed that both cell lines expressed the phagocyte oxidase (phox) cytosolic proteins Rac1, p40phox, and p67phox. With respect to the catalytic flavoheme protein subunit, HaCaT membranes, which expressed p22phox, showed an absorbance peak at 558 nm indicative of a b-type cytochrome. At mRNA levels, both GM16 and HaCaT cells expressed gp91phox homologs Nox1, Nox2, and Nox4, however, HaCaT cells expressed very low levels of Nox1 mRNA. At protein levels, Nox1 was readily detected in HaCaT but was nearly undetectable in GM16 cells. Consistently, Nox activity of HaCaT membranes was demonstrated by electron paramagnetic resonance spin-trapping and cytochrome c reduction, and the activity was sensitive to the flavoprotein inhibitor diphenylene iodonium. V(max) values were 20-fold lower than those reported for phagocytic oxidase. In conclusion, keratinocytes expressed a Nox distinct from the phox isoform of phagocytes providing molecular evidence for a source of superoxide that may regulate cell proliferation and host defense in skin and oral mucosa.

• NADPH oxidases in the vasculature: Molecular features, roles in disease and pharmacological inhibition

  Authors: Stavros Selemidis, Christopher G. Sobey, Kirstin Wingler, Harald H.H.W. Schmidt, Grant R. Drummond

  Pharmacology & Therapeutics.

  Until the 1970s, reactive oxygen species (ROS) were considered merely harmful by-products of aerobic respiration and the driving force behind the evolution of an array of cellular antioxidant enzymesUntil the 1970s, reactive oxygen species (ROS) were considered merely harmful by-products of aerobic respiration and the driving force behind the evolution of an array of cellular antioxidant enzymes with the purpose of rapidly metabolising ROS to minimise their oxidising effects. However, the perception that ROS are only harmful to cells has since been questioned by a burgeoning body of evidence pointing to the existence of enzymes with the dedicated function of generating ROS. NADPH oxidases represent the only known family of enzymes whose sole purpose is to generate ROS. Members of this enzyme family are expressed across mammalian and non-mammalian cells, and influence a multitude of biological functions including host defence and redox signalling. However, although ROS are deliberately generated by NADPH oxidases during normal cell physiology, the observations that their expression and activity is markedly upregulated in the blood vessel wall in a number of cardiovascular ‘high-risk’ states (e.g. hypertension, hypercholesterolemia) implicates them in the oxidative stress that gives rise to artery disease and ultimately heart attacks and strokes. These observations highlight the fact that NADPH oxidases are important therapeutic targets in cardiovascular disease and that, hence, there is clearly a need for the development of selective inhibitors of these enzymes. Here we highlight the structural and biochemical characteristics of the NADPH oxidase family and then comprehensively review the literature on the currently available pharmacological inhibitors of these enzymes with a particular emphasis on their mechanisms of action, isoform selectivity and therapeutic potential in cardiovascular disease.

• Correspondence (reply): In Reply

  Authors: Kirstin Wingler, Harald H H W Schmidt

• Translating the oxidative stress hypothesis into the clinic: NOX versus NOS

  Authors: Melanie E Armitage, Kirstin Wingler, Harald H H W Schmidt, Mylinh La

  Cardiovascular diseases remain the leading cause of death in industrialised nations. Since the pathomechanisms of most cardiovascular diseases are not understood, the majority of therapeuticCardiovascular diseases remain the leading cause of death in industrialised nations. Since the pathomechanisms of most cardiovascular diseases are not understood, the majority of therapeutic approaches are symptom-orientated. Knowing the molecular mechanism of disease would enable more targeted therapies. One postulated underlying mechanism of cardiovascular diseases is oxidative stress, i.e. the increased occurrence of reactive oxygen species such as superoxide. Oxidative stress leads to a dysfunction of vascular endothelium-dependent protective mechanisms. There is growing evidence that this scenario also involves impaired nitric oxide (NO)-cyclic GMP signalling. Out of a number of enzyme families that can produce reactive oxygen species, NADPH oxidases stand out, as they are the only enzymes whose sole purpose is to produce reactive oxygen species. This review focuses on the clinically validated targets of oxidative stress, NO synthase (NOS) and the NO receptor, soluble guanylate cyclase as well as the source of ROS, e.g. NADPH oxidases. We place recent knowledge in the function and regulation of these enzyme families into clinical perspective. For a comprehensive overview of the biology and pharmacology of oxidative stress and possible other sources and targets, we refer to other literature overviews.