TGF-beta1-Induced MAPK activation promotes collagen synthesis, nodule formation, redox stress and cellular senescence in porcine aortic valve interstitial cells.

Background And Aim Of The Study: 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.

Redox regulation of human protease-activated receptor-2 by activated factor X.

Activated factor X (FXa) exerts coagulation-independent actions such as proliferation of vascular smooth muscle cells (SMCs) through the protease-activated receptors PAR-1 and PAR-2. Both receptors are upregulated upon vascular injury but the underlying mechanisms have not been defined. We examined if FXa regulates PAR-1 and PAR-2 in human vascular SMCs.

Regulation of human vascular protease-activated receptor-3 through mRNA stabilization and the transcription factor nuclear factor of activated T cells (NFAT).

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.

Cholesterol induces apoptosis-associated loss of the activated leukocyte cell adhesion molecule (ALCAM) in human monocytes.

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.

High glucose enhances thrombin responses via protease-activated receptor-4 in human vascular smooth muscle cells.

Objective: Diabetes is associated with vascular remodeling and increased thrombin generation. Thrombin promotes vascular smooth muscle cell (SMC) mitogenesis and migration via protease-activated receptors (PAR)-1, PAR-3, and PAR-4. We investigated the effect of high glucose on expression and function of vascular thrombin receptors.

Regulation of functionally active P2Y12 ADP receptors by thrombin in human smooth muscle cells and the presence of P2Y12 in carotid artery lesions.

Objective: The platelet P2Y12 ADP receptor is a well-known target of thienopyridine-type antiplatelet drugs. This study is the first to describe increased transcriptional expression of a functionally active P2Y12 in response to thrombin in human vascular smooth muscle cells (SMC).

Methods And Results: On exposure to thrombin, P2Y12 mRNA was transiently increased, whereas total protein and cell surface expression of P2Y12 were markedly increased within 6 hours and remained elevated over 24 hours.

Thrombin receptors in vascular smooth muscle cells - function and regulation by vasodilatory prostaglandins.

The vast majority of thrombin (>95%) is generated after clotting is completed, suggesting that thrombin formation serves purposes beyond coagulation, such as tissue repair after vessel injury. Two types of vascular thrombin binding sites exist: protease-activated receptors (PARs) and thrombomodulin (TM). Their expression is low in contractile vascular smooth muscle cells (SMC), the dominating subendothelial cell population, but becomes markedly up-regulated upon injury.

B-type natriuretic peptide: endogenous regulator of myocardial structure, biomarker and therapeutic target.

B-type natriuretic peptide (BNP), initially identified in brain tissues, is now recognized as a key cardiac hormone. Numerous studies over the last decade have demonstrated that both exogenous and endogenous BNP prevent left ventricular (LV) hypertrophy in experimental settings, largely via activation of particulate guanylyl cyclase (pGC)-coupled receptors. BNP represents somewhat of a paradox, in that upregulation of BNP expression is widely used as a diagnostic marker for LV hypertrophy, diastolic dysfunction and heart failure in the clinic.

Exploiting cGMP-based therapies for the prevention of left ventricular hypertrophy: NO* and beyond.

Left ventricular hypertrophy (LVH), an increased left ventricular (LV) mass, is common to many cardiovascular disorders, initially developing as an adaptive response to maintain myocardial function. In the longer term, this LV remodelling becomes maladaptive, with progressive decline in LV contractility and diastolic function. Indeed LVH is recognised as an important blood-pressure independent predictor of cardiovascular morbidity and mortality.

Regulation of protease-activated receptor-1 by vasodilatory prostaglandins via NFAT.

Aims: We recently reported that prostacyclin suppresses protease-activated receptor-1 (PAR-1) in human vascular smooth muscle cells (VSMC) via cyclic AMP and protein kinase A. This study examines the downstream mechanisms, particularly the role of nuclear factor of activated T-cells (NFAT).

Methods And Results: Human saphenous vein VSMC were exposed to phorbol 12-myristate 13-acetate (PMA) to induce endogenous cyclooxygenase-2-dependent prostaglandin generation.

Inhibition of calcifying nodule formation in cultured porcine aortic valve cells by nitric oxide donors.

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.

Vitamin D(2) supplementation induces the development of aortic stenosis in rabbits: interactions with endothelial function and thioredoxin-interacting protein.

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.

Transcriptional inhibition of protease-activated receptor-1 expression by prostacyclin in human vascular smooth muscle cells.

Objective: Stimulation of protease-activated receptor-1 (PAR-1) by thrombin causes vascular smooth muscle cell (SMC) mitogenesis and has been implicated in the vascular response to injury. Vascular injury is also associated with enhanced formation of PGE2 and PGI2 (prostacyclin). This study investigates whether PGI2 and PGE2 modify the expression of PAR-1 and the cellular response to thrombin in human SMC.

Endothelial antioxidant actions of dihydropyridines and angiotensin converting enzyme inhibitors.

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).

Antioxidant and nitric oxide-sparing actions of dihydropyridines and ACE inhibitors differ in human endothelial cells.

The effects of dihydropyridine Ca2+ channel blockers (DHP) and ACE inhibitors on superoxide formation and nitric oxide (NO) bioavailability were compared in human EA.Hy926 endothelial cells (EC). EC were stimulated 4 h with angiotensin II (Ang II, 10 nM) +/- study drugs.

Different antioxidative potencies of dihydropyridine calcium channel modulators in various models.

There is evidence that dihydropyridine calcium antagonists (DHP) play a beneficial role during the development of atherosclerosis. Since antioxidative properties of this substance class may be important, we investigated the antioxidative potency of the DHP prototype calcium channel antagonist nifedipine, the long acting calcium channel antagonist lacidipine, the DHP calcium channel agonist Bay K 8644 and the bulky DHP derivate Bay O 5572 (negligible effects on L-type calcium channels) in three different models. Additionally, we examined the potential correlation between lipophilic and antioxidative properties.

Vascular protective effects of dihydropyridine calcium antagonists. Involvement of endothelial nitric oxide.

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.

B-type natriuretic peptide prevents acute hypertrophic responses in the diabetic rat heart: importance of cyclic GMP.

Stimulation of cardiomyocyte guanosine 3',5'-cyclic monophosphate (cyclic GMP) via endothelial-derived nitric oxide (NO) is an important mechanism by which bradykinin and ACE inhibitors prevent hypertrophy. Endothelial NO dysfunction and cardiac hypertrophy are morbid features of diabetes not entirely prevented by ACE inhibitors. In cardiomyocyte/endothelial cell cocultures, bradykinin efficacy is abolished by high-glucose-induced endothelial NO dysfunction.

Antihypertrophic actions of the natriuretic peptides in adult rat cardiomyocytes: importance of cyclic GMP.

Unlabelled: Atrial natriuretic peptide (ANP) prevents hypertrophy of neonatal cardiomyocytes. However, whether this effect is retained in the adult phenotype or if other members of the natriuretic peptide family exhibit similar antihypertrophic properties, has not been elucidated.

Objective: Our objective was to examine whether the natriuretic peptides protect against adult cardiomyocyte hypertrophy in vitro.

Acute antihypertrophic actions of bradykinin in the rat heart: importance of cyclic GMP.

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 3'5'-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.