Henning Morawietz

Publications of Henning Morawietz

• Sphingosine-1-phosphate induces contraction of valvular interstitial cells from porcine aortic valves.

  Authors: Wolfgang Witt, Anett Jannasch, Daniela Burkhard, Torsten Christ, Ursula Ravens, Coy Brunssen, Anja Leuner, Henning Morawietz, Klaus Matschke, Thomas Waldow

  Cardiovascular research. 03/2012; 93(3):490-7.

  Sphingosine-1-phosphate (S1P) has emerged as a potent bioactive lipid with multiple functions in cardiovascular pathophysiology. Potential roles of S1P in heart valve diseases and expression ofSphingosine-1-phosphate (S1P) has emerged as a potent bioactive lipid with multiple functions in cardiovascular pathophysiology. Potential roles of S1P in heart valve diseases and expression of relevant receptors (S1P1, S1P2, or S1P3) in valve tissue and in valvular interstitial cells (VICs), the major cell population with essential functions in maintenance of valvular structure, are currently unknown. Exposure to S1P (62-2000 nM) of cultured VICs from porcine aortic valves on cell culture polystyrene resulted in contraction and nodule formation. The S1P-dependent contraction was completely inhibited by blockers of S1P2, RhoA, and RhoA-associated protein kinase (ROCK). Activated RhoA was clearly increased after S1P treatment, whereas activated Rac1 was only slightly reduced. In addition, exposure to S1P induced a transient increase in cytosolic Ca(2+). Application of channel blockers and other effectors of Ca(2+) homeostasis showed that the S1P effect is largely caused by Ca(2+) release from internal stores. However, resistance to blocking S1P2, different kinetics, as well as concentration dependence exclude a major role of Ca(2+) influx in S1P-induced nodule formation. In order to verify the effects in situ, contractions of valve tissue slices were measured. The S1P-induced isometric contraction of valve leaflets was of similar force amplitude as observed with adrenaline. The effect was fully reversed by blocking S1P2. The results suggest that S1P induces contraction of VICs from porcine aortic valves by signalling via S1P2, RhoA, and ROCK. In this way, S1P may contribute to regulation of tissue tension in aortic valves.

• Endothelial NADPH oxidases: friends or foes?

  Authors: Henning Morawietz

  Basic research in cardiology. 06/2011; 106(4):521-5.

• Arterial flow reduces oxidative stress via an antioxidant response element and Oct-1 binding site within the NADPH oxidase 4 promoter in endothelial cells.

  Authors: Claudia Goettsch, Winfried Goettsch, Melanie Brux, Claudia Haschke, Coy Brunssen, Gregor Muller, Stefan R Bornstein, Nicole Duerrschmidt, Andreas H Wagner, Henning Morawietz

  Basic research in cardiology. 03/2011; 106(4):551-61.

  The main sources of oxidative stress in the vessel wall are nicotine adenine dinucleotide phosphate (NADPH) oxidase (Nox) complexes. The endothelium mainly expresses the Nox4-containing complex;The main sources of oxidative stress in the vessel wall are nicotine adenine dinucleotide phosphate (NADPH) oxidase (Nox) complexes. The endothelium mainly expresses the Nox4-containing complex; however, the mechanism by which shear stress in endothelial cells regulates Nox4 is not well understood. This study demonstrates that long-term application of arterial laminar shear stress using a cone-and-plate viscometer reduces endothelial superoxide anion formation and Nox4 expression. In primary human endothelial cells, we identified a 47 bp 5'-untranslated region of Nox4 mRNA by 5'-rapid amplification of cDNA ends (5'-RACE) PCR. Cloning and functional analysis of human Nox4 promoter revealed a range between -1,490 and -1,310 bp responsible for flow-dependent downregulation. Mutation of an overlapping antioxidative response element (ARE)-like and Oct-1 binding site at -1,376 bp eliminated shear stress-dependent Nox4 downregulation. Consistent with these observations, electrophoretic mobility shift assays (EMSA) demonstrated an enhanced shear stress-dependent binding of Nox4 oligonucleotide containing the ARE-like/Oct-1 binding site, which could be inhibited by specific antibodies against the transcription factors nuclear factor erythroid 2-related factor 2 (Nrf2) and octamer transcription factor 1 (Oct-1). Furthermore, shear stress caused the translocation of Nrf2 and Oct-1 from the cytoplasm to the nucleus. Knockdown of Nrf2 by short hairpin RNA (shRNA) increased Nox4 expression twofold, indicating a direct cross-talk between Nrf2 and Nox4. In conclusion, an ARE-like/Oct-1 binding site was noticed to be essential for shear stress-dependent downregulation of Nox4. This novel mechanism may be involved in the flow-dependent downregulation of endothelial superoxide anion formation.

• Endothelial cells (EC) and endothelial precursor cells (EPC) kinetics in hematological patients undergoing chemotherapy or autologous stem cell transplantation (ASCT).

  Authors: Linda Kideryová, Robert Pytlík, Kateřina Benešová, Romana Veselá, Josef Karban, Hana Rychtrmocová, Winfried Goettsch, Henning Morawietz, Marek Trněný

  Hematological oncology. 12/2010; 28(4):192-201.

  Our objective was to study the kinetics of circulating endothelial cells (EC) and endothelial precursor cells (EPC) in hematological patients during chemotherapy and autologous stem cellOur objective was to study the kinetics of circulating endothelial cells (EC) and endothelial precursor cells (EPC) in hematological patients during chemotherapy and autologous stem cell transplantion (ASCT). Eighteen newly diagnosed patients and 17 patients undergoing ASCT were studied and compared to healthy controls. ECs were evaluated as CD146+CD31+Lin- cells, while EPCs were evaluated as CD34+CD133+Lin-, or CD34+VEGFR2+Lin- cells, or CFU-En colony forming units. Numbers of these cells were evaluated before and after treatment, and, in patients treated with ASCT, during mobilization of hematopoietic progenitors. Both newly diagnosed patients and patients before ASCT had significantly higher number of CD146+CD31+Lin- cells and significantly lower number of CFU-En colonies than healthy controls. These parameters did not return to normal for at least 3 months after chemotherapy or ASCT. Numbers of CFU-En did not correlate either with numbers of CD34+CD133+Lin- cells or with numbers of CD34+VEGFR2+Lin- cells but they did correlate with numbers of CD4+ lymphocytes and NK cells. In conclusion, we have found that hematological patients have higher number of EC and lower numbers of CFU-En than healthy controls and that these parameters do not return to normal after short-term follow-up. Furthermore, our observations support emerging data that CFU-En represent cell population different from flowcytometrically defined EC and endothelial precursors and that their development requires cooperation of monocytes and CD4+ lymphocytes. However, cells forming CFU-En express endothelial surface markers and can contribute to proper endothelial function by NO production.

• Effect of apocynin on NADPH oxidase-mediated oxidative stress-LOX-1-eNOS pathway in human endothelial cells exposed to high glucose.

  Authors: Ashraf Taye, Adel H Saad, Arun Hs Kumar, Henning Morawietz

  European journal of pharmacology. 10/2009;

  Hyperglycemia-induced generation of reactive oxygen species contributes to the development of proatherogenic changes and vasculopathy in diabetes. NADPH oxidase has been recognized as a major sourceHyperglycemia-induced generation of reactive oxygen species contributes to the development of proatherogenic changes and vasculopathy in diabetes. NADPH oxidase has been recognized as a major source of reactive oxygen species in the vasculature and the lectin-like oxLDL receptor-1 (LOX-1) appears to play a crucial role in the pathogenesis of diabetic endothelial dysfunction. The present study aimed to examine the relationships between the hyperglycemia-mediated NADPH oxidase-LOX-1 pathway activation and nitric oxide-mediated endothelial function. In addition, we investigated effect of the NADPH oxidase inhibitor, apocynin on these consequences. In human umbilical artery endothelial cells (HUAECs), the effect of high glucose on expressional regulations and functional consequences of NADPH oxidase subunits, LOX-1 and endothelial nitric oxide synthase (eNOS), in the absence and presence of apocynin (10micromol/l) were evaluated. HUAECs were cultured under normal (5.5mmol/l) or high glucose (30mmol/l) concentrations for 48h in the absence and presence of apocynin. Our results showed that high glucose significantly enhanced the activity and the protein expression of NADPH oxidase subunits, Nox2 and p47(phox). High glucose markedly increased LOX-1 mRNA level and this was functionally reflected on the augmented uptake of Dil-labelled LDL (5micromol/l, 3h) by HUAECs. Furthermore, high glucose attenuated eNOS protein and total nitrite levels. However, apocynin inhibited all these changes. Collectively, our study demonstrates that high glucose-induced oxidative stress via NADPH oxidase activation and this contributed to LOX-1 upregulation and eNOS downregulation in human endothelial cells. Apocynin efficiently reversed these consequences, suggesting its potential role as vasculoprotective agent.

• Inhibition of receptor activator of NF-kappaB ligand by denosumab attenuates vascular calcium deposition in mice.

  Authors: Susann Helas, Claudia Goettsch, Michael Schoppet, Ute Zeitz, Ute Hempel, Henning Morawietz, Paul J Kostenuik, Reinhold G Erben, Lorenz C Hofbauer

  The American journal of pathology. 09/2009; 175(2):473-8.

  Osteoporosis and vascular calcification frequently coincide. A potential mediator of bone metabolism and vascular homeostasis is the triad cytokine system, which consists of receptor activator ofOsteoporosis and vascular calcification frequently coincide. A potential mediator of bone metabolism and vascular homeostasis is the triad cytokine system, which consists of receptor activator of nuclear factor-kappaB (RANK) ligand (RANKL), its receptor RANK, and the decoy receptor osteoprotegerin. Unopposed RANKL activity in osteoprotegerin-deficient mice resulted in osteoporosis and vascular calcification. We therefore analyzed the effects of RANKL inhibition by denosumab, a human monoclonal antibody against RANKL, on vascular calcium deposition following glucocorticoid exposure. Prednisolone pellets were implanted into human RANKL knock-in (huRANKL-KI) mice, which unlike wild-type mice are responsive to denosumab. No histomorphological abnormalities or differences in aortic wall thickness were detected between wild-type and huRANKL-KI mice, regardless of treatment with prednisolone, denosumab, or both. However, concurrent treatment with denosumab reduced aortic calcium deposition of prednisolone-treated huRANKL-KI mice by up to 50%, based on calcium measurement. Of note, aortic calcium deposition in huRANKL-KI mice was correlated negatively with bone mineral density at the lumbar spine (P = 0.04) and positively with urinary excretion of deoxypyridinoline, a marker of bone resorption (P = 0.01). In summary, RANKL inhibition by denosumab reduced vascular calcium deposition in glucocorticoid-induced osteoporosis in mice, which is further evidence for the link between the bone and vascular systems. Therefore, the prevention of bone loss by denosumab might also be associated with reduced vascular calcification in certain conditions.

• Impaired vascular function in small resistance arteries of LOX-1 overexpressing mice on high-fat diet.

  Authors: Birgit Eichhorn, Gregor Muller, Anja Leuner, Tatsuya Sawamura, Ursula Ravens, Henning Morawietz

  Cardiovascular research. 05/2009;

  AIMS: LOX-1 is a major vascular receptor for oxidized low-density lipoprotein (oxLDL). In this study, we analysed the impact of LOX-1 overexpression and high dietary fat intake on vascular functionAIMS: LOX-1 is a major vascular receptor for oxidized low-density lipoprotein (oxLDL). In this study, we analysed the impact of LOX-1 overexpression and high dietary fat intake on vascular function in small resistance arteries. METHODS AND RESULTS: Relaxation of mesenteric arteries was measured using a wire myograph. Compared with the control group, mice overexpressing LOX-1 on a high-fat diet (FD) had preserved vascular smooth muscle relaxation, but impaired endothelium-dependent relaxation via NO. Vascular NO availability was decreased by exaggerated formation of reactive oxygen species and decreased endothelial NO synthase expression. Endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxation via cytochrome P450 metabolites was increased in LOX-1 + FD animals, but did not completely compensate for the loss of NO. Currents of calcium-activated potassium channels with large conductance (BK(Ca) channels) were measured by the voltage-clamp method. The BK(Ca) current amplitudes were not altered in endothelial cells, but highly increased in vascular smooth muscle cells from resistance arteries of LOX-1-overexpressing mice on FD. BK(Ca) currents were activated by low-dose H(2)O(2) and cytochrome P450 metabolites 11,12-EET and 14,15-EET as EDHF in control mice. CONCLUSION: LOX-1 overexpression and FD caused functional changes in endothelial and vascular smooth muscle cells of small resistance arteries.

• Acute atrial tachyarrhythmia induces angiotensin II type 1 receptor-mediated oxidative stress and microvascular flow abnormalities in the ventricles.

  Authors: Andreas Goette, Alicja Bukowska, Dobromir Dobrev, Jan Pfeiffenberger, Henning Morawietz, Denis Strugala, Ingrid Wiswedel, Friedrich-Wilhelm Röhl, Carmen Wolke, Sybille Bergmann, Peter Bramlage, Ursula Ravens, Uwe Lendeckel

  European heart journal. 04/2009;

  Aims Patients with paroxysmal atrial fibrillation (AF) often present with typical angina pectoris and mildly elevated levels of cardiac troponin (non ST-segment elevation myocardial infarction)Aims Patients with paroxysmal atrial fibrillation (AF) often present with typical angina pectoris and mildly elevated levels of cardiac troponin (non ST-segment elevation myocardial infarction) during an arrhythmic event. However, in a large proportion of these patients, significant coronary artery disease is excluded by coronary angiography. Here we explored the potential underlying mechanism of these events. Methods and results A total of 14 pigs were studied using a closed chest, rapid atrial pacing (RAP) model. In five pigs RAP was performed for 7 h (600 b.p.m.; n = 5), in five animals RAP was performed in the presence of angiotensin-II type-1-receptor (AT(1)-receptor) inhibitor irbesartan (RAP+Irb), and four pigs were instrumented without intervention (Sham). One-factor analysis of variance was performed to assess differences between and within the three groups. Simultaneous measurements of fractional flow reserve (FFR) and coronary flow reserve (CFR) before, during, and after RAP demonstrated unchanged FFR (P = 0.327), but decreased CFR during RAP (RAP: 67.7 +/- 7.2%, sham: 97.2 +/- 2.8%, RAP+Irb: 93.2 +/- 3.3; P = 0.0013) indicating abnormal left ventricular (LV) microcirculation. Alterations in microcirculatory blood flow were accompanied by elevated ventricular expression of NADPH oxidase subunit Nox2 (P = 0.039), lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1, P = 0.004), and F(2)-isoprostane levels (P = 0.008) suggesting RAP-related oxidative stress. Plasma concentrations of cardiac troponin-I (cTn-I) increased in RAP (RAP: 613.3 +/- 125.8 pmol/L vs. sham: 82.5 +/- 12.5 pmol/L; P = 0.013), whereas protein levels of eNOS and LV function remained unchanged. RAP+Irb prevented the increase of Nox2, LOX-1, and F(2)-isoprostanes, and abolished the impairment of microvascular blood flow. Conclusion Rapid atrial pacing induces AT(1)-receptor-mediated oxidative stress in LV myocardium that is accompanied by impaired microvascular blood flow and cTn-I release. These findings provide a plausible mechanism for the frequently observed cTn-I elevation accompanied with typical angina pectoris symptoms in patients with paroxysmal AF and normal (non-stenotic) coronary arteries.

• Nitric Oxide, NAD(P)H Oxidase and Atherosclerosis.

  Authors: Gregor Muller, Henning Morawietz

  Antioxidants & redox signaling. 04/2009;

  The endothelial cell layer plays a major role in the development and progression of atherosclerosis. Endothelial NO synthase (eNOS) produces nitric oxide (NO) from L-arginine. NO can rapidly reactThe endothelial cell layer plays a major role in the development and progression of atherosclerosis. Endothelial NO synthase (eNOS) produces nitric oxide (NO) from L-arginine. NO can rapidly react with reactive oxygen species to form peroxynitrite. This reduces NO availability, impairs vasodilatation and mediates proinflammatory and prothrombotic processes such as leukocyte adhesion and platelet aggregation. In the vessel wall, specific NAD(P)H oxidase complexes are major sources of reactive oxygen species. These NAD(P)H oxidases can transfer electrons across membranes to oxygen and generate superoxide anions. The short-lived superoxide anion rapidly dismutates to hydrogen peroxide, which can further increase the production of reactive oxygen species. This can lead to uncoupling of eNOS switching enzymatic activity from NO to superoxide production. This review describes the structure and regulation of different NAD(P)H oxidase complexes. We will also focus on NO/superoxide anion balance as modulated by hemodynamic forces, vasoconstrictors and oxidized low-density lipoprotein. We will then go on to summarize the recent advances defining the role of nitric oxide and NAD(P)H oxidase-derived reactive oxygen species in the development and progression of atherosclerosis. In conclusion, novel mechanisms affecting the vascular NO/superoxide anion balance will allow the development of therapeutic strategies in the treatment of cardiovascular diseases.

• Long-Term Cyclic Strain Downregulates Endothelial Nox4.

  Authors: Claudia Goettsch, Winfried Goettsch, Alexander Arsov, Lorenz C Hofbauer, Stefan R Bornstein, Henning Morawietz

  Antioxidants & redox signaling. 04/2009;

  Endothelial cells in vivo are constantly exposed to mechanical forces like cyclic strain. In endothelial cells, Nox4-containing NAD(P)H oxidase complexes have been identified as major sources ofEndothelial cells in vivo are constantly exposed to mechanical forces like cyclic strain. In endothelial cells, Nox4-containing NAD(P)H oxidase complexes have been identified as major sources of superoxide anion (*O₂^-) formation. In this study, we analyzed the effect of cyclic strain on endothelial ROS formation by electron paramagnetic resonance spectroscopy, cytochrome c assay and dihydroethidium fluorescence, on NO formation by Griess reaction and on gene expression by RT-PCR and Western blot. Primary cultures of human umbilical vein endothelial cells were exposed to 2% to 18% cyclic strain for up to 24 h using the Flexercell system. Long-term application of 5% to 12% cyclic strain down-regulated Nox4 expression and ROS formation in a time-dependent manner. Down-regulation of Nox4 was further confirmed by promoter analysis using dual-luciferase assay. Cu/Zn SOD, MnSOD and catalase expression was decreased after application of chronic 12% cyclic strain. In contrast, endothelial NO formation and eNOS were increased by cyclic strain. Strain-dependent Nox4 down-regulation was abolished by eNOS inhibition with L-NAME. In conclusion, physiological levels of cyclic strain down-regulate Nox4 expression and superoxide anion formation. This novel mechanism might contribute to a vasoprotective balance between NO and superoxide anions in response to physiological mechanical stimulation of endothelial cells.

• Nox4 overexpression activates reactive oxygen species and p38 MAPK in human endothelial cells.

  Authors: Claudia Goettsch, Winfried Goettsch, Gregor Muller, Jochen Seebach, Hans-Joachim Schnittler, Henning Morawietz

  Biochemical and biophysical research communications. 02/2009;

  Nicotine adenine dinucleotide phosphate (NADPH) oxidase (Nox) complexes are the main sources of reactive oxygen species (ROS) formation in the vessel wall. We have used DNA microarray, real-time PCRNicotine adenine dinucleotide phosphate (NADPH) oxidase (Nox) complexes are the main sources of reactive oxygen species (ROS) formation in the vessel wall. We have used DNA microarray, real-time PCR and Western blot to demonstrate that the subunit Nox4 is the major Nox isoform in primary human endothelial cells; we also found high levels of NADPH oxidase subunit p22(phox) expression. Nox4 was localized by laser scanning confocal microscopy within the cytoplasm of endothelial cells. Endothelial Nox4 overexpression enhanced superoxide anion formation and phosphorylation of p38 MAPK. Nox4 downregulation by shRNA has in contrast to TGF-beta no effect on p38 MAPK phosphorylation. We conclude that Nox4 is the major Nox isoform in human endothelial cells, and forms an active complex with p22(phox). The Nox4-containing complex mediates formation of reactive oxygen species and p38 MAPK activation. This is a novel mechanism of redox-sensitive signaling in human endothelial cells.

• Differential roles of PKCalpha and PKCepsilon in controlling the gene expression of Nox4 in human endothelial cells.

  Authors: Hui Xu, Claudia Goettsch, Ning Xia, Sven Horke, Henning Morawietz, Ulrich Förstermann, Huige Li

  Free radical biology & medicine. 05/2008; 44(8):1656-67.

  NADPH oxidases are major sources of superoxide in the vascular wall. This study investigates the role of protein kinase C (PKC) in regulating gene expression of NADPH oxidases. Treatment of humanNADPH oxidases are major sources of superoxide in the vascular wall. This study investigates the role of protein kinase C (PKC) in regulating gene expression of NADPH oxidases. Treatment of human umbilical vein endothelial cells (HUVEC) and HUVEC-derived EA.hy 926 endothelial cells with phorbol 12-myristate 13-acetate (PMA) or phorbol 12,13-dibutyrate led to a PKC-dependent biphasic expression of the gp91phox homolog Nox4. A downregulation of Nox4 was observed at 6 h and an upregulation at 48 h after phorbol ester treatment. The early Nox4 downregulation was associated with a reduced superoxide production, whereas the late Nox4 upregulation was accompanied by a clear enhancement of superoxide. PMA activated the PKC isoforms alpha and epsilon in HUVEC and EA.hy 926 cells. Knockdown of PKCepsilon by siRNA prevented the early downregulation of Nox4, whereas knockdown of PKCalpha selectively abolished the late Nox4 upregulation. Vascular endothelial growth factor (VEGF), which activates PKCalpha but not PKCepsilon in HUVEC, increased Nox4 expression without the initial downregulation. VEGF-induced Nox4 upregulation was associated with an enhanced proliferation and angiogenesis of HUVEC. Both effects could be reduced by inhibition of NADPH oxidase. Thus, a selective inhibition/knockdown of PKCalpha may represent a novel therapeutic strategy for vascular disease.

• Flow-dependent regulation of angiopoietin-2.

  Authors: Winfried Goettsch, Corina Gryczka, Thomas Korff, Evelyn Ernst, Claudia Goettsch, Jochen Seebach, Hans-Joachim Schnittler, Hellmut G Augustin, Henning Morawietz

  Journal of cellular physiology. 03/2008; 214(2):491-503.

  Endothelial cells are constantly exposed to high or low shear stress in arteries and veins by the flowing blood. Angiopoietin-2 (Ang-2) is acting as a critical regulator of vessel maturation andEndothelial cells are constantly exposed to high or low shear stress in arteries and veins by the flowing blood. Angiopoietin-2 (Ang-2) is acting as a critical regulator of vessel maturation and endothelial cell quiescence. In this study, flow-dependent regulation of Ang-2 was analyzed in vitro and in vivo. Ang-2 mRNA, protein expression and release was upregulated by 24 h of low (1 dyne/cm(2)), but downregulated by high flow (30 dyne/cm(2)) in human endothelial cells. Increased endothelial NO synthase expression and NO formation was not affecting regulation of Ang-2 by low or high flow. Low and high flow increased VEGF-A expression. Inhibition of VEGFR-2 prevented upregulation of Ang-2 by low flow, but not downregulation of Ang-2 by high flow. Furthermore, upregulation of Ang-2 by VEGF was reduced by application of high flow. Forkhead box O (FOXO) transcription factor FOXO1 has been shown to regulate Ang-2 expression in endothelial cells. FOXO1 binding activity was reduced by high flow. Nuclear localization of transcription factor FOXO1 was not changed by low flow, but reduced by high flow. In vivo, Ang-2 was higher expressed in veins compared to arteries. Arterial ligation augmented Ang-2 expression in distal arterial low flow areas. Our results support a VEGF-dependent induction of Ang-2 in low flow areas, and FOXO1-dependent downregulation of Ang-2 in high flow areas. These data suggest a new mechanism of flow-dependent regulation of vessel stability and differentiation.

• Chronic NOS inhibition prevents adverse lung remodeling and pulmonary arterial hypertension in caveolin-1 knockout mice.

  Authors: Carsten Wunderlich, Alexander Schmeisser, Christian Heerwagen, Bernd Ebner, Kristin Schober, Ruediger C Braun-Dullaeus, Carsten Schwencke, Michael Kasper, Henning Morawietz, Ruth H Strasser

  Pulmonary pharmacology & therapeutics. 02/2008; 21(3):507-15.

  Recently generated caveolin-1 deficient mice (cav-1 ko) suffer from severe lung fibrosis with marked pulmonary hypertension and arterial hypoxemia and may therefore serve as an useful animal model ofRecently generated caveolin-1 deficient mice (cav-1 ko) suffer from severe lung fibrosis with marked pulmonary hypertension and arterial hypoxemia and may therefore serve as an useful animal model of this devastating human disorder. Accumulating evidence strongly supports the negative regulatory influence of caveolin-1 on endothelial nitric oxide synthase resulting in a constitutive hyperactivation of the nitric oxide (NO) pathway in cav-1 ko. We therefore hypothesized that a disturbed NO signaling is implicated in the evolution of the adverse lung phenotype of cav-1 ko. For this purpose, cav-1 ko of 2 months age were compared with knockout counterparts experiencing 2-month postnatal NO synthase inhibition by NG-nitro-l-arginine methyl ester (L-NAME) treatment. Chronic l-NAME administration prevented adverse lung remodeling in cav-1 ko. Furthermore, l-NAME donation led to a normalized oxygen saturation (91.5+/-1.8% vs. 98.5+/-2.3%, P<0.01, n=10-12), a marked decrease in right ventricular hypertrophy (LV/RV ratio: 4.0+/-0.3 vs. 2.7+/-0.3, P<0.01, n=10-12) and reductions of the elevated pulmonary artery pressure (40.2+/-3.1 mmHg vs. 26.3+/-4.6 mmHg, P<0.01, n=6). Collectively, these improvements resulted in an enhanced exercise capacity of l-NAME-treated cav-1 ko. Finally, we found evidence for enhanced oxidative stress in untreated cav-1 ko which was substantially reduced by chronic l-NAME administration to cav-1 ko. In view of these data, we speculate that a perturbation of NO signaling, together with enhanced O2(-) production originating from NO synthases, may play a pivotal role in the pathogenesis of the adverse pulmonary phenotype seen in cav-1 ko.

• Aldosterone rapidly induces leukocyte adhesion to endothelial cells: a new link between aldosterone and arteriosclerosis?

  Authors: Alexander W Krug, Steffi Kopprasch, Christian G Ziegler, Sandra Dippong, Rusan A Catar, Stefan R Bornstein, Henning Morawietz, Michael Gekle

  Hypertension. 12/2007; 50(5):e156-7.

• NO-mediated regulation of NAD(P)H oxidase by laminar shear stress in human endothelial cells.

  Authors: Nicole Duerrschmidt, Claudia Stielow, Gregor Muller, Patrick J Pagano, Henning Morawietz

  The Journal of physiology. 11/2006; 576(Pt 2):557-67.

  The flowing blood generates shear stress at the endothelial cell surface. In endothelial cells, NAD(P)H oxidase complexes have been identified as major sources of superoxide anion (.O(2)(-))The flowing blood generates shear stress at the endothelial cell surface. In endothelial cells, NAD(P)H oxidase complexes have been identified as major sources of superoxide anion (.O(2)(-)) formation. In this study, we analysed the effect of laminar shear stress on .O(2)(-) formation by cytochrome c reduction assay and on NAD(P)H oxidase subunit expression by standard calibrated competitive reverse transcription-polymerase chain reaction and Western blot in human endothelial cells. Primary cultures of human umbilical vein endothelial cells were exposed to laminar shear stress in a cone-and-plate viscometer for up to 24 h. Short-term application of shear stress transiently induced .O(2)(-) formation. This was inhibited by NAD(P)H oxidase inhibitor gp91ds-tat, but NAD(P)H oxidase subunit expression was unchanged. Long-term arterial laminar shear stress (30 dyne cm(-2), 24 h) down-regulated .O(2)(-) formation, and mRNA and protein expression of NAD(P)H oxidase subunits Nox2/gp91(phox) and p47(phox). In parallel, endothelial NO formation and eNOS, but not Cu/Zn SOD, protein expression was increased. Down-regulation of .O(2)(-) formation, gp91(phox) and p47(phox) expression by long-term laminar shear stress was blocked by l-NAME. NO donor DETA-NO down-regulates .O(2)(-) formation, gp91(phox) and p47(phox) expression in static cultures. In conclusion, our data suggest a transient activation of .O(2)(-) formation by short-term shear stress, followed by a down-regulation of endothelial NAD(P)H oxidase in response to long-term laminar shear stress. NO-mediated down-regulation by shear stress preferentially affects the gp91(phox)/p47(phox)-containing NAD(P)H oxidase complex. This mechanism might contribute to the regulation of endothelial NO/.O(2)(-) balance and the vasoprotective potential of physiological levels of laminar shear stress.

• Endothelial Protection, AT1 blockade and Cholesterol-Dependent Oxidative Stress: the EPAS trial.

  Authors: Henning Morawietz, Sandra Erbs, Jürgen Holtz, Andreas Schubert, Michael Krekler, Winfried Goettsch, Oliver Kuss, Volker Adams, Karsten Lenk, Friedrich W Mohr, Gerhard Schuler, Rainer Hambrecht

  Circulation. 08/2006; 114(1 Suppl):I296-301.

  BACKGROUND: Statins and angiotensin type 1 (AT1) receptor blockers reduce cardiovascular mortality and morbidity. In the Endothelial Protection, AT1 blockade and Cholesterol-Dependent OxidativeBACKGROUND: Statins and angiotensin type 1 (AT1) receptor blockers reduce cardiovascular mortality and morbidity. In the Endothelial Protection, AT1 blockade and Cholesterol-Dependent Oxidative Stress (EPAS) trial, impact of independent or combined statin and AT1 receptor blocker therapy on endothelial expression of anti-atherosclerotic and proatherosclerotic genes and endothelial function in arteries of patients with coronary artery disease were tested. METHODS AND RESULTS: Sixty patients with stable coronary artery disease undergoing elective coronary artery bypass grafting (CABG) surgery were randomized 4 weeks before surgery to: (A) control without inhibition of renin-angiotensin system or statin; (B) statin (pravastatin 40 mg/d); (C) AT1 blockade (irbesartan 150 mg/d); or (D) combination of statin and AT1 blocker in same dosages. Primary end point was a priori therapy-dependent regulation of an anti-atherosclerotic endothelial expression quotient Q including mRNA expression (in arbitrary units measured by real-time polymerase chain reaction) of endothelial nitric oxide synthase and C-type natriuretic peptide, divided by expression of oxidized low-density lipoprotein receptor LOX-1 and NAD(P)H oxidase subunit gp91phox in left internal mammary arteries biopsies obtained by CABG surgery; 49 patients completed the study. Statin therapy increased lnQ from 3.2+/-0.4 to 4.4+/-0.4 significantly versus control. AT(1) blockade showed a trend to increase lnQ to 4.2+/-0.5. Combination of statin and AT1 blocker further increased lnQ to 5.1+/-0.6, but a putative interaction of both therapies in lnQ was not significant. Furthermore, preoperative therapy with statin, AT1 blocker and their combination improved endothelial function in internal mammary artery rings. CONCLUSIONS: Statin and AT1 blocker therapy independently and in combination improve an anti-atherosclerotic endothelial expression quotient and endothelial function.

• Endothelial cell biology: an update. 5th International Symposium on the Biology of Endothelial Cells.

  Authors: Henning Morawietz, Georg Breier

  Thrombosis and haemostasis. 07/2006; 95(6):1025-30.

  The 5th International Symposium on the Biology of Endothelial Cells was held in Dresden, Germany. The meeting included sessions on endothelial cell differentiation, tumor and lymph angiogenesis,The 5th International Symposium on the Biology of Endothelial Cells was held in Dresden, Germany. The meeting included sessions on endothelial cell differentiation, tumor and lymph angiogenesis, endothelial cell junctions and barrier function, bio-mechanical control of endothelial function, oxidative stress and endothelial dysfunction, hypoxia and VEGF-induced signaling, inflammation and angiogenesis. This report summarizes the key findings of the platform presentations of the meeting.

• Leptin, endothelin, NADPH oxidase, and heart failure.

  Authors: Henning Morawietz, Stefan R Bornstein

  Hypertension. 06/2006; 47(5):e20; author reply e20-1.

• Upregulation of endothelin receptor B in human endothelial cells by low-density lipoproteins.

  Authors: Gregor Muller, Rusan A Catar, Bernd Niemann, Matthias Barton, Lilla Knels, Martina Wendel, Henning Morawietz

  Experimental biology and medicine (Maywood, N.J.). 06/2006; 231(6):766-71.

  Low-density lipoproteins (LDLs) represent the most important treatable risk factors for coronary artery disease. Although it has been previously shown that hypercholesterolemia stimulates theLow-density lipoproteins (LDLs) represent the most important treatable risk factors for coronary artery disease. Although it has been previously shown that hypercholesterolemia stimulates the endothelin system, the effects of increased levels of LDL on endothelial endothelin receptors have not been previously studied. In particular, the influence of native and oxidatively modified LDLs (nLDLs and oxLDLs) and the regulatory mechanisms in endothelial cells are currently unknown. Human endothelial cells almost exclusively express the endothelin receptor type B (ET(B)). Therefore, the effect of nLDL and oxLDL on the expression of ET(B) was studied in primary cultures of human umbilical vein endothelial cells (HUVEC). HUVEC were stimulated by nLDL and oxLDL in a time-dependent (1-12 hrs) and dose-dependent (25-100 microg/ml) manner. To analyze signal transduction pathways involved in the regulation of ET(B), protein kinase C (PKC) was inhibited using 100 nM Ro-31-8220. The mRNA expression of ET(B) was determined by quantitative reverse transcription-polymerase chain reaction and ET(B) protein expression by Western blot. Native LDL induced ET(B) mRNA after 1 hr (100 microg/ml, 199 +/- 35%, n = 15, P < 0.05 vs. control). Stimulation of HUVEC with oxLDL increased ET(B) mRNA expression (1 hr, 100 microg/ml oxLDL: 308 +/- 48%, n = 15, P < 0.05 vs. control) as well. Induction of ET(B) was also found on the protein level. nLDL was even more potent than oxLDL in inducing ET(B) protein expression. Induction of ET(B) expression by oxLDL is mediated by PKC. These data demonstrate that low-density lipoproteins even independent of oxidative modification are potent inducers of ET(B) receptors at the mRNA and protein level in HUVEC. Given the nitric oxide-releasing capacity of endothelial ET(B) receptors, this effect may represent a possible vasoprotective mechanism.