Anke Fender - Academia.edu (original) (raw)

Papers by Anke Fender

Journal of leukocyte biology, 2014

Thrombin is not only a central factor in blood coagulation but also stimulates inflammatory proce... more Thrombin is not only a central factor in blood coagulation but also stimulates inflammatory processes, including monocyte responses, via activation of PARs. The signaling lipid S1P is a major determinant of monocyte function. Here, we established an interaction between S1P and human monocyte responses to thrombin. S1P induced PAR-1 and PAR-4 mRNA and total protein expression in human monocytes and U937 cells in a concentration (0.1-10 μM)- and time (1-24 h)-dependent manner, respectively. However, only PAR-4 cell-surface expression was increased significantly by S1P, whereas PAR-1 remained unaffected. This response was associated with activation of the Akt, Erk, and p38 pathway and induction of COX-2 but not COX-1. PAR-4-mediated induction of COX-2 was prevented by the PI3K inhibitor LY (10 μM). Preincubation of human monocytes with S1P (1 μM; 16 h) resulted in an enhanced chemotaxis toward thrombin or to selective AP for PAR-4 but not PAR-1. Furthermore, down-regulation of PAR-4 tr...

The Journal of heart valve disease, 2013

Aortic valve stenosis is a major cause of valve replacement, particularly in the elderly. TGF-bet... more Aortic valve stenosis is a major cause of valve replacement, particularly in the elderly. TGF-beta1 is upregulated in stenotic valves and induces calcification and collagen synthesis in cultured valve interstitial cells. It has been shown previously that TGF-beta1 increases reactive oxygen species (ROS) in these cells in association with calcifying nodule formation, but the cellular signaling pathways responsible for these TGF-beta1-induced effects are not well defined. Cultured porcine aortic valve interstitial cells were used to investigate the effects of inhibitors of TGF-beta1 signaling pathways on 3H-proline incorporation into the extracellular matrix, the peak number of calcifying nodules formed, redox stress as dichlorofluorescein diacetate (DCF-DA) fluorescence, and senescence-associated beta-galactosidase staining. Nodule formation and proline incorporation were inhibited by SB431542, implicating the Smad pathway, by SB203580, implicating the P38 MAPK pathway, and by U0126,...

Pharmacology, 2003

Dihydropyridine calcium antagonists play an important role in the treatment of hypertension and a... more Dihydropyridine calcium antagonists play an important role in the treatment of hypertension and angina pectoris. They lower blood pressure by a well-characterized mechanism of blocking L-type calcium channels in smooth muscle cells. Additionally, there is growing evidence that dihydropyridines also modulate endothelial functions by other mechanisms, since macrovascular endothelial cells do not express L-type calcium channels. A number of studies have demonstrated that dihydropyridine calcium antagonists enhance bioavailability of endothelial nitric oxide (NO). Endothelium-derived NO plays a pivotal role in the regulation of vasorelaxation, leukocyte adhesion and platelet aggregation and an impaired NO release is associated with the genesis and progression of atherosclerotic diseases. This review summarizes results from experimental findings that dihydropyridine calcium antagonists increase endothelial NO formation as well as studies which demonstrate these effects in vivo both in an...

Naunyn-Schmiedeberg's archives of pharmacology, 2014

Activators of protease-activated receptors PAR-1 and PAR-2 such as thrombin and synthetic hexapep... more Activators of protease-activated receptors PAR-1 and PAR-2 such as thrombin and synthetic hexapeptides promote hypertrophy of isolated neonatal cardiomyocytes at pathological concentrations. Since PAR-activating proteases often show dual actions at low vs. high concentrations, the potential hypertrophic effects of low-level PAR activation were examined. In H9c2 cardiomyoblasts, messenger RNA (mRNA) expression of the hypertrophic marker atrial natriuretic peptide (ANP) was significantly increased only by higher concentrations of thrombin, trypsin or the synthetic PAR-2 agonist SLIGRL. The dual PAR-1/PAR-2 agonist SFLLRN did not influence basal ANP mRNA expression in H9c2 cells. Low concentration of thrombin or trypsin (up to 0.1 U/mL) or of the synthetic ligands SFLLRN and SLIGRL (1 μM); however, all suppressed ANP mRNA expression stimulated by angiotensin II (Ang II). The PAR-1 selective ligand TFLLRN exerted a comparable effect as SFLLRN. In adult rat cardiomyocytes, protein synthe...

Journal of Investigative Dermatology, 2014

HA -hyaluronan HAShyaluronan synthase miRNA/miR -MicroRNA SA-β-gal -β-galactosidase

Pharmacology, 2006

by the phorbolester PMA and blocked by the protein kinase C (PKC) inhibitor chelerythrine. Suppre... more by the phorbolester PMA and blocked by the protein kinase C (PKC) inhibitor chelerythrine. Suppression of substance P-evoked NO release by Ang II ( 1 70%, n = 6) was reversed by the PKC inhibitor chelerythrine, the DHP amlodipine and nisoldipine and the ACE inhibitor ramiprilat. Further, Ang II reduces Nox-4 expression by 34.5 8 4.9. Nox-2 expression was not regulated. DHP and ACE inhibitors exert different antioxidant effects in human EC stimulated with Ang II, but both improve NO bioavailability via bradykinin and modulation of redox-regulating enzymes.

Circulation, Jan 4, 2014

Diabetes mellitus predisposes to thrombotic and proliferative vascular remodeling, to which throm... more Diabetes mellitus predisposes to thrombotic and proliferative vascular remodeling, to which thrombin contributes via activation of protease-activated receptor (PAR) 1. However, the use of PAR-1 inhibitors to suppress remodeling may be limited by severe bleeding. We recently reported upregulation of an additional thrombin receptor, PAR-4, in human vascular smooth muscle cells exposed to high glucose and have now examined PAR-4 as a novel mediator linking hyperglycemia, hypercoagulation, and vascular remodeling in diabetes mellitus. PAR-4 expression was increased in carotid atherectomies and saphenous vein specimens from diabetic versus nondiabetic patients and in aorta and carotid arteries from streptozotocin-diabetic versus nondiabetic C57BL/6 mice. Vascular PAR-1 mRNA was not increased in diabetic mice. Ligated carotid arteries from diabetic mice developed more extensive neointimal hyperplasia and showed greater proliferation than arteries from nondiabetic mice. The augmented remod...

Vascular Pharmacology, 2011

The activated leukocyte cell adhesion molecule (ALCAM/CD166) is associated with cell migration an... more The activated leukocyte cell adhesion molecule (ALCAM/CD166) is associated with cell migration and leukocyte invasion into the vessel wall. This study investigates the impact of cholesterol loading on the expression of ALCAM, as compared with P-selectin glycoprotein ligand-1 (PSGL-1), vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) in monocytic U937 cells and human primary monocytes. Cells were enriched with cholesterol by incubation with a cyclodextrin-cholesterol complex. Expression of adhesion molecules and apoptosis was determined by flow cytometry. Migration was quantified by chemotaxis toward serum. Incubation with cholesterol (10-100 μg/ml) for 16 h caused a concentration-dependent increase in apoptosis. Enhanced apoptosis was associated with reduction of ALCAM by N 70%. While PSGL-1 was affected similarly, expression of VCAM-1 was markedly increased by cholesterol and ICAM-1 levels were not regulated. The nonselective caspase/apoptosis inhibitor Q-VD-OPh partially prevented cholesterol-modulated alteration of adhesion molecule expression. Migration of cholesterol-rich monocytic cells toward serum was greatly reduced. This effect was partially restored by Q-VD-OPh and was dependent on ALCAM as shown by ALCAMneutralizing antibodies.

Thrombosis and Haemostasis, 2012

Thrombin exerts coagulation-independent effects on the proliferation and migration of vascular sm... more Thrombin exerts coagulation-independent effects on the proliferation and migration of vascular smooth muscle cells (SMC). Forkhead box-O (FoxO) transcription factors regulate cell proliferation, apoptosis and cell cycle arrest, but a possible functional interaction between thrombin and FoxO factors has not been identified to date. In human cultured vascular SMC, thrombin induced a time-dependent phosphorylation of FoxO1 and FoxO3 but not FoxO4. This effect was mimicked by an activating-peptide (AP) for protease-activated receptor (PAR)-1, and abolished by a PAR-1 antagonist (SCH79797).APs for other PARs were without effect. FoxO1 and FoxO3 phosphorylation were prevented by the PI3 kinase (PI3K) inhibitor LY294002 while inhibitors of ERK1/2 (PD98059) or p38MAPK (SB203580) were ineffective. LY294002 moreover prevented thrombin-stimulated SMC mitogenesis and proliferation. FoxO1 and FoxO3 siRNA augmented basal DNA synthesis and proliferation of SMC. Nuclear content of FoxO proteins decreased time-dependently in response to thrombin, coincided with suppressed expression of the cell cycle regulating genes p21 CIP1 and p27 kip1 by thrombin. FoxO1 siRNA reduced basal p21 CIP1 while FoxO3 siRNA attenuated p27 kip1 expression; thrombin did not show additive effects. LY294002 restored p21 CIP1 and p27 kip1 protein expression. Immunohistochemistry revealed that human native and failed saphenous vein grafts were characterised by the cytosolic presence of p-FoxO factors in co-localisation of p21 CIP1 and p27 kip1 with SMC. In conclusion, thrombin and FoxO factors functionally interact through PI3K/Akt-dependent FoxO phosphorylation leading to expression of cell cycle regulating genes and ultimately SMC proliferation. This may contribute to remodelling and failure of saphenous vein bypass grafts.

Thrombosis and Haemostasis, 2011

Molecular Pharmacology, 2011

Thrombin promotes vascular smooth muscle cell (SMC) proliferation and inflammation via protease-a... more Thrombin promotes vascular smooth muscle cell (SMC) proliferation and inflammation via protease-activated receptor (PAR)-1. A further thrombin receptor, PAR-3, acts as a PAR-1 cofactor in some cell-types. Unlike PAR-1, PAR-3 is dynamically regulated at the mRNA level in thrombin-stimulated SMC. This study investigated the mechanisms controlling PAR-3 expression. In human vascular SMC, PAR-3 siRNA attenuated thrombin-stimulated interleukin-6 expression and extracellular signal-regulated kinases 1/2 phosphorylation, indicating PAR-3 contributes to net thrombin responses in these cells. Thrombin slowed the decay of PAR-3 but not PAR-1 mRNA in the presence of actinomycin D and induced cytosolic shuttling and PAR-3 mRNA binding of the mRNA-stabilizing protein human antigen R (HuR). HuR siRNA prevented thrombin-induced PAR-3 expression. By contrast, forskolin inhibited HuR shuttling and destabilized PAR-3 mRNA, thus reducing PAR-3 mRNA and protein expression. Other cAMP-elevating agents, including the prostacyclin-mimetic iloprost, also down-regulated PAR-3, accompanied by decreased HuR/PAR-3 mRNA binding. Iloprost-induced suppression of PAR-3 was reversed with a myristoylated inhibitor of protein kinase A and mimicked by phorbol ester, an inducer of cyclooxygenase-2. In separate studies, iloprost attenuated PAR-3 promoter activity and prevented binding of nuclear factor of activated T cells (NFAT2) to the human PAR-3 promoter in a chromatin immunoprecipitation assay. Accordingly, PAR-3 expression was suppressed by the NFAT inhibitor cyclosporine A or NFAT2 siRNA. Thus human PAR-3, unlike PAR-1, is regulated post-transcriptionally via the mRNA-stabilizing factor HuR, whereas transcriptional control involves NFAT2. Through modulation of PAR-3 expression, prostacyclin and NFAT inhibitors may limit proliferative and inflammatory responses to thrombin after vessel injury.

Journal of Molecular and Cellular Cardiology, 2000

We have previously demonstrated that bradykinin blocks hypertrophy of isolated cardiomyocytes: th... more We have previously demonstrated that bradykinin blocks hypertrophy of isolated cardiomyocytes: this is dependent on the release of nitric oxide from endothelial cells. In the present study, we investigated the influence of endothelial dysfunction on the antihypertrophic action of bradykinin. Angiotensin II (1 ) induced a 34±2% increase in [ 3 H]phenylalanine incorporation (P<0.001), an in vitro marker of hypertrophy, in adult rat cardiomyocytes co-cultured with bovine aortic endothelial cells. This response was blocked by bradykinin (10 ), but restored by the nitric oxide synthase inhibitor, N -monomethyl--arginine (100 ). However, the antihypertrophic effect of bradykinin in co-culture was abolished by 24 h pretreatment of endothelial cells with high glucose (25 m, to mimic hyperglycemia) and attenuated by hydrogen peroxide (100 , to mimic oxidative stress). Pretreatment with oxidized low-density lipoprotein (100 g/ml for 24 h, to mimic hyperlipidemia) was without effect. The hypertrophic response to angiotensin II was not modified by endothelial cell pretreatment. Furthermore, the ability of bradykinin to elevate cGMP (a marker for nitric oxide) in cardiomyocytes co-cultured with endothelial cells was attenuated by pretreatment with either high glucose or hydrogen peroxide. In conclusion, loss of the cardioprotective action of bradykinin against angiotensin II-induced hypertrophy was associated with impaired nitric oxide release from dysfunctional endothelial cells.

Hypertension, 2002

The antihypertrophic action of angiotensin (Ang)-converting enzyme (ACE) inhibitors in the heart ... more The antihypertrophic action of angiotensin (Ang)-converting enzyme (ACE) inhibitors in the heart is attributed in part to potentiation of bradykinin. Bradykinin prevents hypertrophy of cultured cardiomyocytes by releasing nitric oxide (NO) from endothelial cells, which increases cardiomyocyte guanosine 3Ј5Ј-cyclic monophosphate (cyclic GMP). It is unknown whether cyclic GMP is essential for the action of bradykinin, or whether findings in isolated cardiomyocytes apply in whole hearts, in the presence of other cell types and mechanical/dynamic activity. We now examine the contribution of cyclic GMP to the antihypertrophic action of bradykinin in cardiomyocytes and perfused hearts. In adult rat isolated cardiomyocytes cocultured with bovine aortic endothelial cells, the inhibitory action of bradykinin (10 mol/L) against Ang II (1 mol/L)-induced [ 3 H]phenylalanine incorporation was abolished by the soluble guanylyl cyclase inhibitor [1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one (10 mol/L). In Langendorff-perfused rat hearts, Ang II (10 nmol/L)-induced increases in [ 3 H]phenylalanine incorporation and atrial natriuretic peptide mRNA expression were prevented by bradykinin (100 nmol/L), the NO donor sodium nitroprusside (3 mol/L), and the ACE inhibitor ramiprilat (100 nmol/L). The acute antihypertrophic action of bradykinin was accompanied by increased left ventricular cyclic GMP, and the ramiprilat effect was attenuated by HOE 140 (1 mol/L, a B 2 -kinin receptor antagonist) or [1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one (100 nmol/L). In conclusion, bradykinin exerts a direct inhibitory action against the acute hypertrophic response to Ang II in rat isolated hearts, and elevation of cardiomyocyte cyclic GMP may be an important antihypertrophic mechanism used by bradykinin and ramiprilat in the heart. (Hypertension. 2002;40: 498-503.)

Heart, Lung and Circulation, 2000

Heart, Lung and Circulation, 2003

European Journal of Pharmacology, 2006

Dihydropyridines and angiotensin converting enzyme inhibitor effects on superoxide and nitric oxi... more Dihydropyridines and angiotensin converting enzyme inhibitor effects on superoxide and nitric oxide (NO) were compared in high glucose (20 mM, 24 h)-treated human Ea.hy 926 endothelial cells. High glucose stimulated superoxide both extracellularly (lucigenin chemiluminescence, cytochrome c reduction) and intracellularly (dihydrorhodamine 123 fluorescence). The dihydropyridines amlodipine, nisoldipine, BayK 8644 or the angiotensin converting enzyme inhibitors captopril and enalaprilat attenuated extra-and intracellular superoxide formation; nifedipine blocked extracellular increases only, ramiprilat was without antioxidant effect. Dihydropyridines and captopril also prevented NADPH-driven superoxide release. Antioxidant actions were blunted by a bradykinin B 2 receptor antagonist or an inhibitor of p38 mitogen activated protein kinase (MAPK), and were accompanied by improved NO release (amperometric sensor). p38MAPK inhibition prevented the NO-sparing actions of dihydropyridines but not angiotensin converting enzyme inhibitors. Thus, dihydropyridines and angiotensin converting enzyme inhibitors limit high glucose-induced superoxide formation and improve NO bioavailability in human endothelial cells, in part via bradykinin and p38MAPK.

European Journal of Pharmacology, 2008

Understanding of the pathophysiology of aortic valve stenosis (AVS) and finding potentially effec... more Understanding of the pathophysiology of aortic valve stenosis (AVS) and finding potentially effective treatments are impeded by the lack of suitable AVS animal models. A previous study demonstrated the development of AVS in rabbits with vitamin D 2 and cholesterol supplementation without any hemodynamic changes in the cholesterol supplemented group alone. The current study aimed to determine whether AVS develops in an animal model with vitamin D 2 supplementation alone, and to explore pathophysiological mechanisms underlying this process. The effects of 8 weeks' treatment with vitamin D 2 alone (n = 8) at 25,000 IU/4 days weekly on aortic valve structure and function were examined in male New Zealand white rabbits. Echocardiographic aortic valve backscatter (AV BS ), transvalvular velocity, and transvalvular pressure gradient were utilized to quantitate changes in valve structure and function. Valvular histology/ immunochemistry and function were examined after 8 weeks. Changes in valves were compared with those in endothelial function and in valvular measurement of thioredoxin-interacting protein (TXNIP), a marker/mediator of reactive oxygen species-induced oxidative stress. Vitamin D 2 treated rabbits developed AVS with increased AV BS (17.6 ± 1.4 dB vs 6.7 ± 0.8 dB, P b 0.0001), increased transvalvular velocity and transvalvular pressure gradient (both P b 0.01 via 2-way ANOVA) compared to the control group. There was associated valve calcification, lipid deposition and macrophage infiltration. Endothelial function was markedly impaired, and intravalvular TXNIP concentration increased. In this model, vitamin D 2 induces the development of AVS with histological features similar to those of early AVS in humans and associated endothelial dysfunction/ redox stress. AVS development may result from the loss of nitric oxide suppression of TXNIP expression.

European Journal of Pharmacology, 2009

Calcific aortic stenosis displays some similarities to atherosclerosis including evidence of endo... more Calcific aortic stenosis displays some similarities to atherosclerosis including evidence of endothelial dysfunction. Whether nitric oxide (NO), which is produced by valvular endothelium, has direct protective effects extending to calcification processes in aortic valve cells has not previously been examined. In vitro calcifying nodules in porcine aortic valve interstitial cell cultures, formed in response to transforming growth factor-beta1 (TGF-beta1) 5 ng/ml, were inhibited by NO donors DETA-NONOate 5-100 microM, and sodium nitroprusside (SNP) 3 microM. Raising intracellular cGMP concentrations, via 8-bromo cGMP 1 mM or via brain natiuretic peptide and C-type natiuretic peptide 0.1 microM, inhibited TGF-beta1-induced nodule formation, potentially implicating the cGMP pathway in the NO effect. Stimulation of interstitial cells with substance P or calcium ionophone (A23187) caused NO release and increased intracellular cGMP respectively. However in the presence of TGF-beta1 basal levels of NO production via nitric oxide synthase (NOS) were insufficient to affect nodule formation. Increased dihydroethidium (DHE) fluorescence in response to TGF-beta1, which was inhibited by DETA-NONOate and TEMPOL, suggested a role for intracellular superoxide in TGF-beta1 signalling. Moreover, nodule formation was suppressed by superoxide scavengers TEMPOL, hydralazine and polyethylene glycol-superoxide dismutase (PEG-SOD), but not SOD. In conclusion, NO donors, or agents raising intracellular cGMP levels, may protect aortic valve interstitial cells from early events leading to calcification.

Diabetologia, 2004

Aims/hypothesis. Chronic exposure to high concentrations of glucose has consistently been demonst... more Aims/hypothesis. Chronic exposure to high concentrations of glucose has consistently been demonstrated to impair endothelium-dependent, nitric oxide (NO)-mediated vasodilation. In contrast, several clinical investigations have reported that acute exposure to high glucose, alone or in combination with insulin, triggers vasodilation. The aim of this study was to examine whether elevated glucose itself stimulates endothelial NO formation or enhances insulin-mediated endothelial NO release. Methods. We measured NO release and vessel tone ex vivo in porcine coronary conduit arteries (PCAs). Intracellular Ca 2+ was monitored in porcine aortic endothelial cells (PAECs) by fura-2 fluorescence. Expression of the Na + /glucose cotransporter-1 (SGLT-1) was assayed in PAECs and PCA endothelium by RT-PCR. Results. Stimulation of PCAs with D-glucose, but not the osmotic control L-glucose, induced a transient increase in NO release (EC 50 ≈10 mmol/l), mediated by a rise in intracellular Ca 2+ levels due to an influx from the extracellular space. This effect was abolished by inhibitors of the plasmalemmal Na + /Ca 2+ exchanger (dichlorobenzamil) and the SGLT-1 (phlorizin), which was found to be expressed in aortic and coronary endothelium. Alone, D-glucose did not relax PCA, but did augment the effect of insulin on NO release and vasodilation. Conclusions/interpretation. An increased supply of extracellular D-glucose appears to enhance the activity of the endothelial isoform of nitric oxide synthase by increasing intracellular Na + concentrations via SGLT-1, which in turn stimulates an extracellular Ca 2+ influx through the Na + /Ca 2+ exchanger. This mechanism may be responsible for glucose-enhanced, insulin-dependent increases in tissue perfusion (including coronary blood-flow), thus accelerating glucose extraction from the blood circulation to limit the adverse vascular effects of prolonged hyperglycaemia.