Involvement of rho-kinase in agonists-induced contractions of arteriosclerotic human arteries

A comprehensive review on ziconotide

Managing severe chronic pain is a challenging task, given the limited effectiveness of available pharmacological and non-pharmacological treatments. This issue continues to be a significant public health concern, requiring a substantial therapeutic response. Ziconotide, a synthetic peptide initially isolated from Conus magus in 1982 and approved by the US Food and Drug Administration and the European Medicines Agency in 2004, is the first-line intrathecal method for individuals experiencing severe chronic pain refractory to other therapeutic measures. Ziconotide produces powerful analgesia by blocking N-type calcium channels in the spinal cord, which inhibits the release of pain-relevant neurotransmitters from the central terminals of primary afferent neurons. However, despite possessing many favorable qualities, including the absence of tolerance development, respiratory depression, and withdrawal symptoms (largely due to the absence of a G-protein mediation mechanism), ziconotide's application is limited due to factors such as intrathecal administration and a narrow therapeutic window resulting from significant dose-related undesired effects of the central nervous system. This review aims to provide a comprehensive and clinically relevant summary of the literatures concerning the pharmacokinetics and metabolism of intrathecal ziconotide. It will also describe strategies intended to enhance clinical efficacy while reducing the incidence of side effects. Additionally, the review will explore the current efforts to refine the structure of ziconotide for better clinical outcomes. Lastly, it will prospect potential developments in the new class of selective N-type voltage-sensitive calcium-channel blockers.

Comparison of Endothelial Dysfunction in Coronary Arteries with Bare Metal and 2nd-Generation Drug-Eluting Stents

Aims: Previous studies suggested that implantation with a 1st-generation DES was associated with coronary endothelial dysfunction, which was associated with Rho-kinase activation. Second-generation drug-eluting stents (DESs) may preserve coronary endothelial function in stented coronary arteries; however, because of methodological limitations, further study is needed to clarify the association between 2 ^nd -generation DESs and coronary endothelial dysfunction.

Methods: We retrospectively analysed the CuVIC trial database, where we identified 112 patients who underwent coronary stenting in the left coronary arteries with either a bare metal stent (BMS, n =53) or 2 ^nd -generation DES ( n =59). We compared vasomotions of target vessels with stents and non-target vessels without stents. Furthermore, we measured the Rho-kinase activation detected in mononucleocytes from aortic and coronary sinus blood.

Results: ACh-induced vasoconstrictive responses of target vessels were not enhanced with a 2 ^nd -generation DES (45±21% vs. 44±20%, P =0.56, paired t -test), but significantly enhanced in the coronary arteries with a BMS (50±18% vs. 42±20%, P =0.002). Rho-kinase activation did not differ between patients with a BMS and 2 ^nd -generation DES. In the target vessels with a BMS, large late lumen loss and acute coronary syndrome (ACS) at the index percutaneous coronary intervention (PCI) were associated with ACh-induced enhanced coronary vasoconstrictive responses.

Conclusions: Evaluation of ACh-induced vasomotion of target vessels comparing with non-target vessels revealed that 2 ^nd -generation DESs were not associated with coronary endothelial dysfunction in target vessels, nor activation of Rho-kinase in the coronary sinus blood 6-8 months after stenting.

Prognostic Impacts of Comorbid Significant Coronary Stenosis and Coronary Artery Spasm in Patients With Stable Coronary Artery Disease

BACKGROUND Stable coronary artery disease is caused by a variable combination of organic coronary stenosis and functional coronary abnormalities, such as coronary artery spasm. Thus, we examined the clinical importance of comorbid significant coronary stenosis and coronary spasm. METHODS AND RESULTS We enrolled 236 consecutive patients with suspected angina who underwent acetylcholine provocation testing for coronary spasm and fractional flow reserve (FFR) measurement. Among them, 175 patients were diagnosed as having vasospastic angina (VSA), whereas the remaining 61 had no VSA (non-VSA group). The patients with VSA were further divided into the following 3 groups based on angiography and FFR: no organic stenosis (≤50% luminal stenosis; VSA-alone group, n=110), insignificant stenosis of FFR>0.80 (high-FFR group, n=36), and significant stenosis of FFR≤0.80 (low-FFR group, n=29). The incidence of major adverse cardiovascular events, including cardiovascular death, nonfatal myocardial infarction, urgent percutaneous coronary intervention, and hospitalization attributed to unstable angina was evaluated. All patients with VSA received calcium channel blockers, and 28 patients (95%) in the low-FFR group underwent a planned percutaneous coronary intervention. During a median follow-up period of 656 days, although the incidence of major adverse cardiovascular events was low and comparable among non-VSA, VSA-alone, and high-FFR groups, the low-FFR group had an extremely poor prognosis (non-VSA group, 1.6%; VSA-alone group, 3.6%; high-FFR group, 5.6%; low-FFR group, 27.6%) (P<0.001). Importantly, all 8 patients with major adverse cardiovascular events in the low-FFR group were appropriately treated with percutaneous coronary intervention and calcium channel blockers. CONCLUSIONS These results indicate that patients with VSA with significant coronary stenosis represent a high-risk population despite current guideline-recommended therapies, suggesting the importance of routine coronary functional testing in this population.

Regulation of RhoA/ROCK and sustained arterial contraction by low cytosolic Ca2+ levels during prolonged depolarization of arterial smooth muscle

The role of L-type Ca²⁺ channels (LTCCs) and RhoA/Rho kinase (ROCK) on depolarization-induced sustained arterial contraction lasting several minutes is already known. However, in vivo, vascular smooth muscle cells can be depolarized for longer periods, inducing substantial inactivation of LTCCs and markedly reducing Ca²⁺ influx into the myocytes. We have examined, in femoral arterial rings, the role of LTCCs and RhoA/ROCK during long-lasting depolarization. Our results reveal a new vasoreactive response after 20-30min of depolarization in 2.5mM external Ca²⁺ that has not been identified previously with shorter stimuli. Prolonged depolarization-induced arterial contraction was permanently abolished when arterial rings were treated with 100nM external Ca²⁺ or 20nM nifedipine. However, when Ca²⁺ influx was restricted, applying ~7μM external Ca²⁺ solution or 3nM nifedipine, vasorelaxation was transient, and isometric force slowly increased after 30min and maintained its level until the end of the stimulus. Under these conditions, arterial contraction showed the same temporal course of RhoA activity and was sensitive to fasudil, nifedipine and cyclopiazonic acid. Ca²⁺-response curve in β-escin permeabilized arteries was also sensitive to ROCK inhibitors. Thus, although long-lasting depolarization inactivates LTCCs, the reduced Ca²⁺ entry can induce a detectable arterial contraction via RhoA/ROCK activation.

IRAP inhibition using HFI419 prevents moderate to severe acetylcholine mediated vasoconstriction in a rabbit model

Coronary artery vasospasm (constriction) caused by reduced nitric oxide bioavailability leads to myocardial infarction. Reduced endothelial release of nitric oxide by the neurotransmitter acetylcholine, leads to paradoxical vasoconstriction as it binds to smooth muscle cell M3 receptors. Thus, inhibition of coronary artery vasospasm will improve clinical outcomes. Inhibition of insulin regulated aminopeptidase has been shown to improve vessel function, thus we tested the hypothesis that HFI419, an inhibitor of insulin regulated aminopeptidase, could reduce blood vessel constriction to acetylcholine. The abdominal aorta was excised from New Zealand white rabbits (n=15) and incubated with 3mM Hcy to induce vascular dysfunction in vitro for 1h. HFI419 was added 5min prior to assessment of vascular function by cumulative doses of acetylcholine. In some rings, vasoconstriction to acetylcholine was observed in aortic rings after pre-incubation with 3mM homocysteine. Incubation with HFI419 inhibited the vasoconstrictive response to acetylcholine, thus improving, but not normalizing, vascular function (11.5±8.9% relaxation vs 79.2±37% constriction, p<0.05). Similarly, in another group with mild vasoconstriction, HFI419 inhibited this effect (34.9±4.6% relaxation vs 11.1±5.2%, constriction, p<0.05). HFI419 had no effect on control aorta or aorta with mild aortic dysfunction. The present study shows that HFI419 prevents acetylcholine mediated vasoconstriction in dysfunctional blood vessels. HFI419 had no effect on normal vasodilation. Our results indicate a therapeutic potential of HFI419 in reducing coronary artery vasospasm.

RhoA/Rho-Kinase in the Cardiovascular System

Twenty years ago, Rho-kinase was identified as an important downstream effector of the small GTP-binding protein, RhoA. Thereafter, a series of studies demonstrated the important roles of Rho-kinase in the cardiovascular system. The RhoA/Rho-kinase pathway is now widely known to play important roles in many cellular functions, including contraction, motility, proliferation, and apoptosis, and its excessive activity induces oxidative stress and promotes the development of cardiovascular diseases. Furthermore, the important role of Rho-kinase has been demonstrated in the pathogenesis of vasospasm, arteriosclerosis, ischemia/reperfusion injury, hypertension, pulmonary hypertension, and heart failure. Cyclophilin A is secreted by vascular smooth muscle cells and inflammatory cells and activated platelets in a Rho-kinase-dependent manner, playing important roles in a wide range of cardiovascular diseases. Thus, the RhoA/Rho-kinase pathway plays crucial roles under both physiological and pathological conditions and is an important therapeutic target in cardiovascular medicine. Recently, functional differences between ROCK1 and ROCK2 have been reported in vitro. ROCK1 is specifically cleaved by caspase-3, whereas granzyme B cleaves ROCK2. However, limited information is available on the functional differences and interactions between ROCK1 and ROCK2 in the cardiovascular system in vivo. Herein, we will review the recent advances about the importance of RhoA/Rho-kinase in the cardiovascular system.

Cyclophilin A in cardiovascular homeostasis and diseases

Vascular homeostasis is regulated by complex interactions between many vascular cell components, including endothelial cells, vascular smooth muscle cells (VSMCs), adventitial inflammatory cells, and autonomic nervous system. The balance between oxidant and antioxidant systems determines intracellular redox status, and their imbalance can cause oxidative stress. Excessive oxidative stress is one of the important stimuli that induce cellular damage and dysregulation of vascular cell components, leading to vascular diseases through multiple pathways. Cyclophilin A (CyPA) is one of the causative proteins that mediate oxidative stress-induced cardiovascular dysfunction. CyPA was initially discovered as the intracellular receptor of the immunosuppressive drug cyclosporine 30 years ago. However, recent studies have established that CyPA is secreted from vascular cell components, such as endothelial cells and VSMCs. Extracellular CyPA augments the development of cardiovascular diseases. CyPA secretion is regulated by Rho-kinase, which contributes to the pathogenesis of vasospasm, arteriosclerosis, ischemia/reperfusion injury, hypertension, pulmonary hypertension, and heart failure. We recently reported that plasma CyPA levels are significantly higher in patients with coronary artery disease, which is associated with increased numbers of stenotic coronary arteries and the need for coronary intervention in such patients. Furthermore, we showed that the vascular erythropoietin (Epo)/Epo receptor system plays an important role in production of nitric oxide and maintenance of vascular redox state and homeostasis, with a potential mechanistic link to the Rho-kinase-CyPA pathway. In this article, I review the data on the protective role of the vascular Epo/Epo receptor system and discuss the roles of the CyPA/Rho-kinase system in cardiovascular diseases.

Pathogenesis of Systemic Sclerosis

Systemic scleroderma (SSc) is one of the most complex systemic autoimmune diseases. It targets the vasculature, connective tissue-producing cells (namely fibroblasts/myofibroblasts), and components of the innate and adaptive immune systems. Clinical and pathologic manifestations of SSc are the result of: (1) innate/adaptive immune system abnormalities leading to production of autoantibodies and cell-mediated autoimmunity, (2) microvascular endothelial cell/small vessel fibroproliferative vasculopathy, and (3) fibroblast dysfunction generating excessive accumulation of collagen and other matrix components in skin and internal organs. All three of these processes interact and affect each other. The disease is heterogeneous in its clinical presentation that likely reflects different genetic or triggering factor (i.e., infection or environmental toxin) influences on the immune system, vasculature, and connective tissue cells. The roles played by other ubiquitous molecular entities (such as lysophospholipids, endocannabinoids, and their diverse receptors and vitamin D) in influencing the immune system, vasculature, and connective tissue cells are just beginning to be realized and studied and may provide insights into new therapeutic approaches to treat SSc.

Effects of statin on circulating microRNAome and predicted function regulatory network in patients with unstable angina

BACKGROUND

Statin therapy plays a pivotal role in stabilizing the plaque for unstable angina (UA) patients although its mechanism(s) remains largely unexplored. Here we aim to identify microRNAs (miRNAs) mediating the protective effect of statins in UA patients.

METHODS

MiRNAs Array was carried out to compare the circulating whole blood miRNA profile of UA patients treated with (n = 10) and without statin (n = 10) and plasma miRNA profile UA patients treated with (n = 5) and without statin (n = 5). 22 whole blood miRNAs and 19 plasma miRNAs were found significantly upregulated in statin group. Targets of these miRNAs were predicted by algoritms: Targetscan, Miranda and Diana microT, then clustered according to functions and cell types by using the Database for Annotation, Visualization and Integrated Discovery (DAVID). To reveal the enriched function pathways in human atherosclerotic plaque, we analyzed microarray data from GEO database, Coronary atherosclerotic plaque (n = 80); macrophages in ruptured plaque (n = 11); carotid atheroma plaque (n = 64); advanced carotid atherosclerotic plaque (n = 29) using Reactome database. Integrated analysis indicated that statin induced miRNAs mainly regulate the signaling pathways of Rho GTPase and hemostasis in human atherosclerotic lesion. In vulnerable plaque, additional immune system signaling was also targeted.

RESULTS

The data showed target genes regulated by these statin induced miRNAs majorly expressed in i) plaque macrophage and platelet, where they were involved in hemostasis process; ii) in monocyte to regulate NGF apoptosis; iii) and in endothelial cell function in Rho GTPase pathway. Integrate analysis indicated that statin induced miRNAs mainly regulate the signaling pathways of Rho GTPase and hemostasis in human atherosclerotic lesion.

CONCLUSIONS

Our study suggest that statin induces the expression of multiple miRNAs in the circulation of UA patient, which play important roles by regulating signal pathways critical for the pathogenesis of UA.

Endothelin-1 and endothelin-2 initiate and maintain contractile responses by different mechanisms in rat mesenteric and cerebral arteries

BACKGROUND AND PURPOSE

Endothelin (ET)-1 and ET-2 cause potent long-lasting vasoconstrictions by tight binding to smooth muscle ETA receptors. We tested the hypotheses that different mechanisms mediate initiation and maintenance of arterial contractile responses to ET-1 and ET-2 and that this differs among vascular beds.

EXPERIMENTAL APPROACH

Segments of rat mesenteric resistance artery (MRA) and basilar artery (BA) were studied in wire myographs with and without functional antagonists.

KEY RESULTS

Sensitivity and maximum of MRA contractile responses to ET-1 were not, or only moderately, reduced by stimulation of soluble GC, AC or K(+) -channels and by an inhibitor of receptor-operated ion channels. However, each of these reduced maintenance of ET-1 effects and relaxed ET-1-induced contractions in MRA. A calcium channel antagonist did not alter sensitivity, maximum and maintenance of ET-1 effects, but relaxed ET-1-induced contractions in MRA. A PLC inhibitor prevented contractile responses to ET-1 and ET-2 in MRA and BA, and relaxed ET-1- and ET-2-induced responses in MRA and ET-1 effects in BA. A Rho-kinase inhibitor did not modify sensitivity, maximum and maintenance of responses to both peptides in both arteries but relaxed ET-2, but not ET-1, effects in MRA and ET-1 effects in BA.

CONCLUSIONS AND IMPLICATIONS

PLC played a key role in arterial contractile responses to ETs, but ET-1 and ET-2 initiated and maintained vasoconstriction through different mechanisms, and these differed between MRA and BA. Selective functional antagonism may be considered for agonist- and vascular bed selective pharmacotherapy of ET-related diseases.

Small G Proteins in the Cardiovascular System: Physiological and Pathological Aspects

Small G proteins exist in eukaryotes from yeast to human and constitute the Ras superfamily comprising more than 100 members. This superfamily is structurally classified into five families: the Ras, Rho, Rab, Arf, and Ran families that control a wide variety of cell and biological functions through highly coordinated regulation processes. Increasing evidence has accumulated to identify small G proteins and their regulators as key players of the cardiovascular physiology that control a large panel of cardiac (heart rhythm, contraction, hypertrophy) and vascular functions (angiogenesis, vascular permeability, vasoconstriction). Indeed, basal Ras protein activity is required for homeostatic functions in physiological conditions, but sustained overactivation of Ras proteins or spatiotemporal dysregulation of Ras signaling pathways has pathological consequences in the cardiovascular system. The primary object of this review is to provide a comprehensive overview of the current progress in our understanding of the role of small G proteins and their regulators in cardiovascular physiology and pathologies.

Increased leukocyte Rho-kinase activity in a population with acute coronary syndrome

Accumulating evidence suggests that Rho-associated kinase (ROCK) may be important in the pathogenesis of atherosclerosis and coronary vasospasm. In the present study, we investigated whether ROCK activity is increased in acute coronary syndrome (ACS) patients. Twenty-one patients with ACS (12 males, mean age 58.0±8.0 years) and 20 control subjects (10 males, mean age 55.0±6.0 years) were enrolled. Blood samples were obtained and demographics were recorded. Peripheral leukocyte ROCK activity was determined by the ratio of phospho-myosin‑binding subunit (P-MBS) on myosin light-chain phosphatase to total MBS. Compared with the control subjects, ROCK activity was significantly increased in ACS patients (0.69±0.07 vs. 0.45±0.04, P<0.001). There was no apparent correlation between the lipid levels (total cholesterol and low-density lipoprotein) and ROCK activity (r=0.17, P>0.05; r=0.08, P>0.05; respectively). However, ROCK activity correlated with mean arterial pressure (r=0.58; P<0.01). ROCK activity is increased in ACS patients indicating that this may be a novel serological marker of ACS.

ROS-mediated downregulation of MYPT1 in smooth muscle cells: a potential mechanism for the aberrant contractility in atherosclerosis

Reactive oxygen species (ROS) mediates the aberrant contractility in hypertension. Abnormal contractility occurs in atherosclerotic vessels but changes in proteins that regulate contractility remain poorly understood. Myosin phosphatase (MP) activity, which regulates smooth muscle relaxation, is regulated by the phosphorylation of its regulatory subunit, MP targeting subunit 1 (MYPT1). In the present study, we examined the roles of ROS in MP subunit expression both in cultured human aortic smooth muscle cells (HASMCs) and during atherosclerosis progression in apolipoprotein E-knockout (apoE-KO) mice. Furthermore, the effect of decreased MYPT1 on actin cytoskeleton and cell migration activity was assessed in HASMCs. Short hairpin RNA-mediated knockdown of MYPT1 increased stress fibers and attenuated platelet-derived growth factor-induced cell migration in HASMCs. Superoxide anion-inducing agent LY83583 downregulated MYPT1 mRNA and protein levels, but did not affect the phosphorylation of MYPT1 and catalytic subunit of MP, PP1δ. The LY83583-induced decrease in MYPT1 was abolished by co-treating with superoxide dismutase or by inhibiting NADPH oxidase with diphenyleneiodonium. Treatment of peroxynitrite, but not hydrogen peroxide (H2O2), downregulated MYPT1 protein expression and induced MYPT1 phosphorylation without affecting mRNA levels. Co-treatment with a proteasome inhibitor, MG-132, eliminated peroxynitrite-induced MYPT1 downregulation. In apoE-KO mice, MYPT1 protein, but not mRNA, levels were markedly decreased in 16-week- and 24-week-old mice. Oral estrogen treatment, which was previously shown to decrease aortic ROS levels, upregulated aortic MYPT1 expression. Moreover, reduction in MYPT1 expression correlated with increased aortic sensitivity toward vasoconstrictors. These results suggested that during atherosclerosis progression oxidative stress mediates the downregulation of MYPT1, which may inhibit smooth muscle cell migration and contribute to the aberrant contractility.

Possible roles of 5-HT in vein graft failure due to intimal hyperplasia 5-HT, nitric oxide and vein graft

For vascular occlusive disease, an autologous vein graft is the most suitable conduit for arterial reconstruction. Intimal hyperplasia, resulting from the migration and proliferation of vascular smooth muscle cells, is a major obstacle to patency after vein grafting. The degree to which the function of nitric oxide (NO) in the vein graft is preserved has been reported to be associated with the magnitude of intimal hyperplasia. Serotonin (5-HT) is released from platelets in the vascular system and plays physiological roles in controlling the vascular tone. The subtype receptors contributing to the 5-HT-induced mechanical responses vary by vessel type (artery and vein) and among species (dogs, rabbits, rats, and so on). Recent studies have demonstrated that 5-HT induces vasoconstriction through the activation of 5-HT2A receptors in smooth muscle cells or vasodilatation through the activation of endothelial 5-HT1B receptors in arteries from various animals. However, the effects of 5-HT have not been clarified in grafted veins. We herein demonstrate the responses to 5-HT in un-operated veins and then autogenous vein grafts. Next, we describe the effects of chronic in vivo administration of Rho-kinase inhibitors and 5-HT2A receptor antagonists, both of which reduce the 5-HT-induced contraction and intimal hyperplasia in vein grafts. Further studies targeting 5-HT are required to evaluate its possible benefits for autologous vein grafts with respect to vasospasm, function, and patency.

Association analysis of polymorphisms in ROCK2 with cardiovascular disease in a Chinese population

Background

Rho-kinase (ROCK) has been shown to play an important role in cardiovascular disease such as coronary artery disease (CAD) and hypertension. Recently, common variants of ROCK2 have been reported to influence blood pressure, but the relationship between common ROCK2 variants and cardiovascular disease has not been extensively studied in the Chinese population.

Methods

To derive a more precise estimation of their relationship, we screened for the common variants by direct sequencing of all exons of ROCK2, and then we performed genetic association analyses in a CAD case–control study, including a total of 1344 cases and 1267 ethnically and geographically matched controls.

Results

Unconditional logistic regression showed that no significant association between common variants in the coding region of ROCK2 and CAD was observed in our study (for rs978906, OR = 0.92, 95% CI 0.72–1.20 and P = 0.63; for rs2230774, OR = 0.90, 95% CI 0.70–1.16 and P = 0.47; for rs56304104, OR = 0.97, 95% CI 0.70–1.31 and P = 0.83; respectively).

Conclusions

The relationship between the ROCK2 polymorphisms and cardiovascular disease risk cannot be entirely discounted and warrants further evaluation in a large population.

Characteristics of the actions by which 5-hydroxytryptamine affects electrical and mechanical activities in rabbit jugular vein graft

BACKGROUND AND PURPOSE

The vasomodulating actions of 5-HT in vein grafts, and the underlying mechanisms, remain to be fully clarified. Here, we characterized the actions by which 5-HT affects electrical and mechanical activities in rabbit autologous jugular vein grafts.

EXPERIMENTAL APPROACH

Smooth muscle cell (SMC) membrane potential and isometric tension were measured in vein grafts 4 weeks after implantation into carotid arteries. Changes in the expression of 5-HT receptor subtypes and in myosin heavy chain isoforms (SM1, SM2 and SMemb) were examined by immunohistochemistry and Western blot analysis.

KEY RESULTS

The walls of grafted veins displayed massive increases in the number of SM1- and SM2-positive SMCs. 5-HT induced a large depolarization and contraction that were each reduced by both 5-HT(2A) - and 5-HT(1B/1D) -receptor antagonists. The 5-HT-induced contraction was not modified by a 5-HT₇ -receptor antagonist. The 5-HT₇ -receptor-selective agonist AS 19 did not induce relaxation during the contraction to prostaglandin F(2α) . Immunohistochemical and Western blot analyses revealed that immunoreactive responses against 5-HT(2A) and 5-HT(1B/1D) receptors were increased in the vein graft.

CONCLUSIONS AND IMPLICATIONS

5-HT is able to induce a large contraction in rabbit autologous jugular vein grafts through (i) an increased number of differentiated contractile SMCs; (ii) an increased number of SMCs expressing contractile 5-HT(2A) - and 5-HT(1B/1D) receptors; and (iii) a down-regulation of the function of the relaxant SMC 5-HT₇ receptors. These changes in the vein graft may help it to resist the higher pressure present on the arterial side of the circulation.

Vascular involvement in systemic sclerosis (scleroderma)

Systemic sclerosis (SSc) is an acquired multiorgan connective tissue disease with variable mortality and morbidity dictated by clinical subset type. The etiology of the basic disease and pathogenesis of the systemic autoimmunity, fibrosis, and fibroproliferative vasculopathy are unknown and debated. In this review, the spectrum of vascular abnormalities and the options currently available to treat the vascular manifestations of SSc are discussed. Also discussed is how the hallmark pathologies (ie, how autoimmunity, vasculopathy, and fibrosis of the disease) might be effected and interconnected with modulatory input from lysophospholipids, sphingosine 1-phosphate, and lysophosphatidic acid.

Rho-kinase: important new therapeutic target in cardiovascular diseases

Rho-kinase (ROCKs) belongs to the family of serine/threonine kinases and is an important downstream effector of the small GTP-binding protein RhoA. There are two isoforms of Rho-kinase, ROCK1 and ROCK2, and they have different functions with ROCK1 for circulating inflammatory cells and ROCK2 for vascular smooth muscle cells. It has been demonstrated that the RhoA/Rho-kinase pathway plays an important role in various fundamental cellular functions, including contraction, motility, proliferation, and apoptosis, leading to the development of cardiovascular disease. The important role of Rho-kinase in vivo has been demonstrated in the pathogenesis of vasospasm, arteriosclerosis, ischemia-reperfusion injury, hypertension, pulmonary hypertension, stroke, and heart failure. Furthermore, the beneficial effects of fasudil, a selective Rho-kinase inhibitor, have been demonstrated for the treatment of several cardiovascular diseases in humans. Thus the Rho-kinase pathway is an important new therapeutic target in cardiovascular medicine.

Modification of the detrimental effect of TNF-α on human endothelial progenitor cells by fasudil and Y27632

Exposure of human endothelial progenitor cells (EPCs) to tumor necrosis factor-α (TNF-α) reduced their number and biological activity. Yet, signal transduction events linked to TNF-α action are still poorly understood. To address this issue, we examined the possible effect of fasudil and Y27632, two inhibitors of Rho kinase pathway, which is involved in endothelial dysfunction, atherosclerosis, and in- flammation. Results demonstrated that incubation with fasudil starting from 50 μM but not Y27632 determined a dose-dependent improvement of EPC number during exposure to TNF-α (P < 0.05 vs. TNF-α alone). Analysis of the signal transduction pathway activated by TNF-α revealed that the increased expression of p-p38 was not significantly altered by fasudil. Instead, fasudil blocked the TNF-α induced phosphorylation of Erk1/2 (P < 0.05 vs. TNF-α) as well as the inhibitor of Erk1/2-specific phosphorylated form, i.e., PD98059 (P < 0.05 vs. TNF-α). These results were confirmed by analysis of these kinases by confocal microscopy. Finally, 2D-DIGE and MALDI-TOF/TOF analysis of EPCs treated with fasudil revealed increased expression levels of an actin-related protein and an adenylyl cyclase associated protein and decreased expression levels of proteins related to radical scavenger and nucleotide metabolism. These findings suggest that fasudil positively affects EPC number and that other major signals might take part to this complex pathway.

Rho-kinase inhibition: a novel therapeutic target for the treatment of cardiovascular diseases

The Rho/rho-kinase (ROCK) pathway has an important role in the pathogenesis of several cardiovascular diseases. The activation of ROCK is involved in the regulation of vascular tone, endothelial dysfunction, inflammation and remodeling. The inhibition of ROCK has a beneficial effect in a variety of cardiovascular disorders. Evidence from animal models and from clinical use of ROCK inhibitors, such as Y-27632, fasudil and statins (i.e. pleiotropic effects), supports the hypothesis that ROCK is a potential therapeutic target. This review provides a current understanding of the role of ROCK pathway in the regulation of vascular function and the use of ROCK inhibitors in the treatment of cardiovascular disorders.

Role of Rho/Rho-kinase and NO/cGMP signaling pathways in vascular function prior to atherosclerosis

AIM

Atherosclerosis is a cardiovascular disease; however, there is little information on signal transduction for vascular function in the early stage of atherosclerosis. In this work, we investigated the role of Rho/Rho-kinase and nitrogen oxide (NO)/cyclic GMP (cGMP) signaling pathways in the aorta prior to atherosclerosis.

METHODS

Tension, the expression of RhoA protein, Rho-kinase activity and the cGMP level were measured using endothelium-intact or -denuded aorta prepared from apolipoprotein E-deficient (apoE-KO) and C57BL/6 wild-type (WT) mice at 2 months of age.

RESULTS

Phenylephrine (PE) induced less maximal contraction in the endothelium-denuded aorta from apoE-KO than from WT mice. A Rho-kinase inhibitor (Y-27632) reduced more effectively the contraction of apoE-KO than WT mice, but their RhoA proteins and Rho-kinase activities were not so different. Acetylcholine caused larger relaxation of the PE-stimulated, endothelium-intact aorta in apoE-KO due to endothelial NO release than WT mice. The basal cGMP level in the endothelium-intact aorta of apoE-KO mice was higher than that of WT.

CONCLUSIONS

Smooth muscle contraction via alpha(1)-adrenergic receptor shows higher dependency on Rho-kinase activity, suggesting down-regulation of the mechanism different from Rho/Rho kinase signaling in the aorta prior to atherosclerosis. Endothelium-dependent relaxation is also intensified through the NO/cGMP pathway.

Effects of fasudil on early atherosclerotic plaque formation and established lesion progression in apolipoprotein E-knockout mice

Rho kinases have been shown to be involved in the pathogenesis of atherosclerosis. This study examined the effects of fasudil, a specific Rho kinase inhibitor, on plaque development and progression in atherosclerotic mice. Sixty apolipoprotein E-knockout (apoE-KO) mice were fed a high-fat diet. Mice started to receive fasudil at the same time as fat feeding (early treatment), or after 12 weeks of fat feeding (delayed treatment). In each administrative schedule, mice were divided into three groups: low dose fasudil group (30 mg/kg/day), high dose fasudil group (100mg/kg/day) and control group (tap water) (n=10, respectively). Plaque size was determined by using ultrasound biomicroscopy (UBM) and histological examinations. Brachiocephalic artery UBM analysis showed that in early treatment, both doses of fasudil significantly reduced lesion size compared with the controls (P<0.05). In delayed-fasudil treatment, plaque area was reduced by 54% (P<0.05) after 12 weeks of treatment at a high dose of fasudil (100mg/kg/day). The UBM findings were confirmed by histological studies at the corresponding arterial sites. The beneficial effect was also observed in the left common carotid arteries that delayed-fasudil treatment reduced the plaque size in a dose-dependent manner. The arterial intima-medial thickness (IMT) and maximal flow velocity of both arteries were lower in fasudil-treated group (100mg/kg/day) in comparison with the control mice. Furthermore, fasudil treatment (100mg/kg/day) reduced the macrophage accumulation in atherosclerotic lesions. However, fasudil had no effects on blood pressure and plasma lipid concentrations in both studies. In conclusion, our studies showed that blocking Rho kinase reduced both the early development and later progression of atherosclerotic plaques in apoE-KO mice by using a novel micro-ultrasound approach.

c-Src tyrosine kinase, a critical component for 5-HT2A receptor-mediated contraction in rat aorta

Serotonin (5-hydroxytryptamine, 5-HT) receptors (5-HTRs) play critical roles in brain and cardiovascular functions. In the vasculature, 5-HT induces potent vasoconstrictions, which in aorta are mainly mediated by activation of the 5-HT(2A)R subtype. We previously proposed that one signalling mechanism of 5-HT-induced vasoconstriction could be c-Src, a member of the Src tyrosine kinase family. We now provide evidence for a central role of c-Src in 5-HT(2A)R-mediated contraction. Inhibition of Src kinase activity with 10 mum 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2) prior to contraction resulted in approximately 90-99% inhibition of contractions induced by 5-HT or by alpha-methyl-5-HT (5-HT(2)R agonist). In contrast, PP2 pretreatment only partly inhibited contractions induced by angiotensin II and the thromboxane A(2) mimetic, U46619, and had no significant action on phenylephrine-induced contractions. 5-Hydroxytryptamine increased Src kinase activity and PP2-sensitive tyrosine-phosphorylated proteins. As expected for c-Src identity, PP2 pretreatment inhibited 5-HT-induced contraction with an IC(50) of approximately 1 mum. Ketanserin (10 nm), a 5-HT(2A) antagonist, but not antagonists of 5-HT(2B)R (100 nm SB204741) or 5-HT(2C)R (20 nm RS102221), prevented 5-HT-induced contractions, mimicking PP2 and implicating 5-HT(2A)R as the major receptor subtype coupled to c-Src. In HEK 293T cells, c-Src and 5-HT(2A)R were reciprocally co-immunoprecipitated and co-localized at the cell periphery. Finally, 5-HT-induced Src activity was unaffected by inhibition of Rho kinase, supporting a role of c-Src upstream of Rho kinase. Together, the results highlight c-Src activation as one of the early and pivotal mechanisms in 5-HT(2A)R contractile signalling in aorta.

Serotonin induces vasoconstriction of smooth muscle cell-rich neointima through 5-hydroxytryptamine2A receptor in rabbit femoral arteries

BACKGROUND

Smooth muscle cell (SMC)-rich intima is a morphological feature of atherosclerotic lesions that is observed in eroded plaque and spastic arteries. Arteries with SMC-rich intima are susceptible to vasoconstriction or vasospasm against some vasoactive agents.

OBJECTIVE

The present study evaluates the contribution of SMC-rich intima to thrombogenic vasoconstriction.

METHODS

We established SMC-rich neointima by damaging rabbit femoral arteries using balloons and then measured the isometric tension of the femoral strips against 5-hydroxytryptamine (5-HT), adenosine diphosphate, adenosine triphosphate and thrombin.

RESULTS

Among these agents, only 5-HT induced a hypercontractile response of the injured arteries with SMC-rich neointima, compared with non-injured arteries. Smooth muscle cells of both the neointima and media expressed 5-HT(2A) receptor, and sarpogrelate, a selective 5-HT(2A) receptor antagonist significantly inhibited the hypercontraction. Furthermore, 5-HT induced contraction of separated neointima and hypercontraction of separated media compared with non-injured media. Sarpogrelate and fasudil, a specific Rho-kinase inhibitor, significantly suppressed such contraction of both the neointima and media of injured arteries.

CONCLUSIONS

These results suggest that 5-HT plays a crucial role in thrombogenic vasoconstriction, and that SMC-rich intima as well as media directly contributes to the hypercontractile response of atherosclerotic vessels through the 5-HT(2A) receptor and the Rho-kinase pathway.

The pathology of scleroderma vascular disease

Systemic sclerosis is characterized by three distinct pathologic processes: fibrosis, cellular/humoral autoimmunity, and specific vascular changes. Although a mild vasculitis may sometimes be present, the vascular pathology of scleroderma is not necessarily inflammatory and is best characterized as a vasculopathy. In this article, the authors propose that SSc vasculopathy is the result of an early event involving vascular injury that eventuates in a vicious cycle mediated in part by the immune process. The subsequent vascular malformation and rarefaction may be a function of systemic angiogenic dysregulation, with over expression of vascular endothelial growth factor but a lack of proper interactions with smooth muscle cells needed to stabilize and organize blood vessels.

Distinct effects of contraction agonists on the phosphorylation state of cofilin in pulmonary artery smooth muscle

We hypothesized that agonist-induced contraction correlates with the phospho-cofilin/cofilin (P-CF/CF) ratio in pulmonary artery (PA) rings and cultured smooth muscle cells (PASMCs). PA rings were used for isometric contractions and along with PASMCs for assay of P-CF/CF by isoelectric focusing and immunoblotting. The P-CF/CF measured 22.5% in PA and differentiated PASMCs, but only 14.8% in undifferentiated PASMCs. With comparable contraction responses in PA, endothelin-1 (100 nM) and norepinephrine (1 μM) induced a 2-fold increase of P-CF/CF, while angiotensin II (1 μM) induced none. All agonists activated Rho-kinase and LIMK2, and activation was eliminated by inhibition of Rho-kinase. Microcystin LF (20 nM) potentiated the angiotensin II, but not the 5-hydroxytryptamine (1 μM)-mediated increase of P-CF/CF. In conclusion, all tested agonists activate the Rho-kinase-LIMK pathway and increase P-CF/CF. Angiotensin II activates PP2A and counteracts the LIMK-mediated CF phosphorylation. CF phosphorylation stabilizes peripheral actin structures and may contribute to the maximal contraction of PA.

Polyphenols modulate calcium-independent mechanisms in human arterial tissue-engineered vascular media

BACKGROUND

In the present study, an arterial tissue-engineered vascular media (TEVM) was produced from cultured human smooth muscle cells of the umbilical artery and we took advantage of this model to evaluate the regulation of contraction and the signalling pathways of polyphenols in arteries.

METHODS

Cultured human smooth muscle cells of the umbilical artery were used to produce arterial TEVMs. Contraction experiments were performed to determine intracellular targets involved in the modulation of contraction by polyphenols extract from red wine, Provinols (SEPPIC Groupe Air Liquide, Paris, France).

RESULTS

Smooth muscle cells in arterial TEVM displayed a differentiated phenotype as demonstrated by the expression of alpha-smooth muscle actin, a vascular smooth muscle-specific marker, and tissue contraction in response to vasoconstrictor and vasodilator agents. Contractions caused by histamine were associated with an increase in [Ca(2+)](i) and a Ca(2+)-independent signalling pathway. The latter pathway involved mechanisms sensitive to protein kinase C, myosin light chain kinase, and Rho-associated protein kinase inhibitors. The regulation of contraction induced by Provinols shows that treatment of arterial TEVM with this compound significantly decreased histamine-induced contraction. This effect was associated with the inhibition of the Rho-associated protein kinase pathway and the decrease in alpha-smooth muscle actin expression.

CONCLUSION

The use of arterial TEVM, brings new insights into the mechanisms by which polyphenols regulate vascular contraction in the human artery.

Heat shock augments myosin phosphatase target-subunit phosphorylation

Our previous study demonstrated that heat shock augmented vascular contraction. In the present study, we hypothesized that heat shock augments myosin phosphatase target-subunit (MYPT1) phosphorylation resulting in augmented vascular contraction. Endothelium-denuded rat aortic rings were mounted in organ baths, exposed to heat shock (42 degrees C for 45 min), and subjected to contraction 4 h after the heat shock followed by Western blot analysis for MLC(20) (the 20 kDa light chains of myosin II) or MYPT1. The contractile responses in both control and heat shock-treated aorta were inhibited by Y27632, an inhibitor of Rho-kinase. The level of the MLC(20) and MYPT1(Thr855) phosphorylation in response to KCl was higher in heat shock-treated aorta than that in timed-control. The increased MYPT1(Thr855) phosphorylation was inhibited by Y27632 (1.0 microM) in parallel with inhibition of MLC(20) phosphorylation and vascular contraction. These results indicate that heat shock augments MYPT1 phosphorylation resulting in augmented vascular contraction.

PSGL-1 and mTOR regulate translation of ROCK-1 and physiological functions of macrophages

Rho-associated kinases (ROCKs) are critical molecules involved in the physiological functions of macrophages, such as chemotaxis and phagocytosis. We demonstrate that macrophage adherence promotes rapid changes in physiological functions that depend on translational upregulation of preformed ROCK-1 mRNA, but not ROCK-2 mRNA. Before adherence, both ROCK mRNAs were present in the cytoplasm of macrophages, whereas ROCK proteins were undetectable. Macrophage adherence promoted signaling through P-selectin glycoprotein ligand-1 (PSGL-1)/Akt/mTOR that resulted in synthesis of ROCK-1, but not ROCK-2. Following synthesis, ROCK-1 was catalytically active. In addition, there was a rapamycin/sirolimus-sensitive enhanced loading of ribosomes on preformed ROCK-1 mRNAs. Inhibition of mTOR by rapamycin abolished ROCK-1 synthesis in macrophages resulting in an inhibition of chemotaxis and phagocytosis. Macrophages from PSGL-1-deficient mice recapitulated pharmacological inhibitor studies. These results indicate that receptor-mediated regulation at the level of translation is a component of a rapid set of mechanisms required to direct the macrophage phenotype upon adherence and suggest a mechanism for the immunosuppressive and anti-inflammatory effects of rapamycin/sirolimus.

Long-term inhibition of Rho kinase suppresses intimal thickening in autologous vein grafts in rabbits

BACKGROUND

Rho kinase plays an important role in vascular smooth muscle cell (VSMC) contraction and other cellular functions, such as proliferation, migration, and apoptosis. Recent studies have demonstrated that long-term inhibition of Rho kinase suppresses coronary artery spasm and vascular lesion formation after arterial injury. In the cardiovascular surgery field, intimal thickening in vein grafts is the major cause of late graft failure, for which no effective treatment has yet been developed. In this study, we examined whether long-term inhibition of Rho kinase suppresses intimal thickening in autologous vein grafts in rabbits.

METHODS

Male rabbits were randomly divided into two groups and received normal chow (control group) or a special chow containing 0.09% fasudil (fasudil group). After oral administration, fasudil is metabolized to a specific Rho kinase inhibitor, hydroxyfasudil. Each group underwent reversed autologous vein graft surgery with the internal jugular vein into the left common carotid artery. At 1, 2, and 4 weeks after the operation, we examined the extent of intimal thickening of the graft and VSMC proliferation and apoptosis.

RESULTS

The intimal thickening was significantly suppressed in the fasudil group compared with the control group at 2 and 4 weeks after the operation. In the fasudil group, VSMC proliferation was suppressed at 1 and 2 weeks after the operation, whereas VSMC apoptosis was enhanced at 2 weeks after the procedure.

CONCLUSIONS

These results indicate that Rho kinase is substantially involved in the pathogenesis of intimal thickening of vein grafts and that it is an important therapeutic target for the prevention of graft failure.

Agonist- and depolarization-induced signals for myosin light chain phosphorylation and force generation of cultured vascular smooth muscle cells

Phosphorylation of myosin light chain (MLC) and contraction of differentiated smooth muscle cells in vascular walls are regulated by Ca2+ -dependent activation of MLC kinase, and by Rho-kinase- or protein-kinases-C-dependent inhibition of MLC phosphatase (MLCP). We examined regulatory pathways for MLC kinase and MLCP in cultured vascular smooth muscle cells (VSMCs), and for isometric force generation of VSMCs reconstituted in collagen fibers. Protein levels of RhoA, Rho-kinase and MYPT1 (a regulatory subunit of MLCP) were upregulated in cultured VSMCs, whereas a MLCP inhibitor protein, CPI-17, was downregulated. Endothelin-1 evoked a steady rise in levels of Ca2+, MLC phosphorylation and the contractile force of VSMCs, whereas angiotensin-II induced transient signals. Also, Thr853 phosphorylation of MYPT1 occurred in response to stimuli, but neither agonist induced phosphorylation of MYPT1 at Thr696. Unlike fresh aortic tissues, removal of Ca2+ or addition of voltage-dependent Ca2+ -channel blocker did not inhibit contractions of reconstituted VSMC fibers induced by agonists or even high concentrations of extracellular K+ ions. Inhibitors of Ins(1,4,5)P3-receptor and Rho-kinase antagonized agonist-induced or high-K+ -induced contraction in both reconstituted fibers and fresh tissues. These results indicate that both Ins(1,4,5)P3-induced Ca2+ release and Rho-kinase-induced MYPT1 phosphorylation at Thr853 play pivotal roles in MLC phosphorylation of cultured VSMCs where either Ca2+ -influx or CPI-17-MLCP signaling is downregulated.

Molecular aspects of arterial smooth muscle contraction: focus on Rho

The vascular smooth muscle cell is a highly specialized cell whose primary function is contraction and relaxation. It expresses a variety of contractile proteins, ion channels, and signalling molecules that regulate contraction. Upon contraction, vascular smooth muscle cells shorten, thereby decreasing the diameter of a blood vessel to regulate the blood flow and pressure. Contractile activity in vascular smooth muscle cells is initiated by a Ca(2+)-calmodulin interaction to stimulate phosphorylation of the light chain of myosin. Ca(2+)-sensitization of the contractile proteins is signaled by the RhoA/Rho-kinase pathway to inhibit the dephosphorylation of the light chain by myosin phosphatase, thereby maintaining force. Removal of Ca(2+) from the cytosol and stimulation of myoson phosphatase initiate the relaxation of vascular smooth muscle.

Beneficial Acute Effects of Rho-Kinase Inhibitor in Patients With Pulmonary Arterial Hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is a poor prognostic disease with limited treatment options. Rho-kinase is involved in the pathophysiology of several diseases underlying smooth muscle hypercontraction, so the purpose of this study was to investigate the efficacy of fasudil, a Rho-kinase inhibitor, in patients with PAH.

METHODS AND RESULTS

Fasudil 30 mg was intravenously injected over 30 min in 8 patients (all female, mean +/- SD, 41+/-11 years) with PAH. The lowest total pulmonary resistance (TPR) time was within 30-60 min after administration. Administration of fasudil decreased TPR from 1,069+/-573 dyne . s . cm (-5) to 809+/-416 dyne . s . cm(-5) (p<0.005) and mean pulmonary arterial pressure from 41.3+/-12.8 mmHg to 37.9+/-14.6 mmHg (p<0.05). The cardiac index was increased from 2.42+/-0.73 L . min(-1) . m(-2) to 2.84+/-0.79 L . min(-1) . m(-2) (p<0.02). Systemic vascular resistance and systolic systemic arterial pressure (SAP) were decreased (p<0.005, p=0.09, respectively), but the decrease in SAP was small (-6.4+/-9.1 mmHg).

CONCLUSION

These results suggest that Rho-kinase is involved in the pathogenesis of human PAH and that fasudil is a novel therapeutic agent.

Impact of oxidized low density lipoprotein on vascular cells

Oxidized LDL (OxLDL) is a proatherogenic lipoprotein, accumulating in the vascular wall and contributing to the pathogenesis of vascular dysfunction early in the development of atherosclerosis. Enhanced serum levels of OxLDL, as well as antibodies against its epitopes, are predictive for endothelial dysfunction and coronary heart disease. While enhanced oxidative stress is one factor triggering formation of OxLDL, OxLDL itself has been identified as a potent stimulus for vascular oxygen radical formation, causing a vicious circle. OxLDL-induced O(2)(-) formation, largely through activation of NADPH oxidase, but also through uncoupling of endothelial NO-synthase and through direct O(2)(-) release, leads to endothelial dysfunction. Furthermore, OxLDL-induced O(2)(-) formation has a strong impact on tissue remodeling, resulting in either cell growth - proliferation or hyperplasia - or apoptotic cell death. The effect of OxLDL on cell cycle regulation is mediated by activation of the small GTPase RhoA and consequent regulation of p27(KIP1), a key enzyme of the cell cycle. In addition, OxLDL-induced activation of RhoA sensitizes the contractile apparatus of the vessel wall, enhancing the contractile tonus and favoring vasospasm. Thus, through a variety of mechanisms, OxLDL importantly contributes to vascular dysfunction and remodeling.

5-Hydroxytryptamine augments migration of human aortic smooth muscle cells through activation of RhoA and ERK

The purpose of this study was to elucidate the mechanism of 5-hydroxytryptamine (5-HT, serotonin) action on migration of vascular smooth muscle cells. Migration of cultured human aortic smooth muscle cells (HASMCs), evaluated using time-lapse microscopy, was significantly enhanced by 5-HT at concentrations of 1-100 nM. The enhancing effect of 5-HT on cell migration was markedly inhibited in the presence of ketanserin, a 5-HT2 receptor antagonist, but not by GR 55562, a 5-HT1 receptor antagonist. Activities of RhoA and ERK were increased by 5-HT, and the increase in cell migration by 5-HT was abolished in the presence of U0126, a MEK1/2 inhibitor, or Y-27632, a Rho-kinase inhibitor. Activation of ERK was strongly inhibited by Y-27632. 5-HT-induced formation of stress fiber and detachment of uropod (trailing edge) were abolished by Y-27632. Thus, 5-HT has a potent enhancing action on migration of HASMCs due to an increase in stress fiber formation by 5-HT2 receptor stimulation followed by activation of the Rho-kinase and ERK pathways.

M-RIP targets myosin phosphatase to stress fibers to regulate myosin light chain phosphorylation in vascular smooth muscle cells

Vascular smooth muscle cell contraction and relaxation are directly related to the phosphorylation state of the regulatory myosin light chain. Myosin light chains are dephosphorylated by myosin phosphatase, leading to vascular smooth muscle relaxation. Myosin phosphatase is localized not only at actin-myosin stress fibers where it dephosphorylates myosin light chains, but also in the cytoplasm and at the cell membrane. The mechanisms by which myosin phosphatase is targeted to these loci are incompletely understood. We recently identified myosin phosphatase-Rho interacting protein as a member of the myosin phosphatase complex that directly binds both the myosin binding subunit of myosin phosphatase and RhoA and is localized to actin-myosin stress fibers. We hypothesized that myosin phosphatase-Rho interacting protein targets myosin phosphatase to the contractile apparatus to dephosphorylate myosin light chains. We used RNA interference to silence the expression of myosin phosphatase-Rho interacting protein in human vascular smooth muscle cells. Myosin phosphatase-Rho interacting protein silencing reduced the localization of the myosin binding subunit to stress fibers. This reduction in stress fiber myosin phosphatase-Rho interacting protein and myosin binding subunit increased basal and lysophosphatidic acid-stimulated myosin light chain phosphorylation. Neither cellular myosin phosphatase, myosin light chain kinase, nor RhoA activities were changed by myosin phosphatase-Rho interacting protein silencing. Furthermore, myosin phosphatase-Rho interacting protein silencing resulted in marked phenotypic changes in vascular smooth muscle cells, including increased numbers of stress fibers, increased cell area, and reduced stress fiber inhibition in response to a Rho-kinase inhibitor. These data support the importance of myosin phosphatase-Rho interacting protein-dependent targeting of myosin phosphatase to stress fibers for regulating myosin light chain phosphorylation state and morphology in human vascular smooth muscle cells.

Efficacy and safety of fasudil in patients with stable angina: a double-blind, placebo-controlled, phase 2 trial

OBJECTIVES

This study sought to evaluate the efficacy and safety of fasudil, an orally available rho kinase inhibitor, in patients with stable angina.

BACKGROUND

Several small, non-placebo-controlled trials suggest that fasudil reduces myocardial ischemia in patients with stable or vasospastic angina.

METHODS

In a multicenter, double-blind, placebo-controlled, randomized trial, the efficacy and safety of fasudil were evaluated in stable angina patients. Of the 206 patients screened, 84 patients with reproducible exercise times were randomized 1:1 to fasudil or placebo. Nitroglycerin as needed and a beta- or calcium-channel blocker were allowed. Fasudil or matching placebo was force-titrated from 20 mg three times daily to 80 mg twice daily with 20 mg twice-daily increments every two weeks. Symptom-limited exercise testing was performed after two, four, six, and eight weeks of treatment.

RESULTS

At peak, exercise duration was significantly improved at all visits in both groups, although exercise duration was numerically greater in patients receiving fasudil versus those receiving placebo. Time to > or =1 mm ST-segment depression was increased with fasudil at both peak and trough compared with placebo (172.1 s vs. 44.0 s, p = 0.001, and 92.8 s vs. 26.4 s, p = 0.02, respectively). Fasudil improved Seattle Angina Questionnaire scores. No significant differences in Canadian Cardiovascular Society class, time to angina, or frequency of angina or nitroglycerin use were noted between groups. Fasudil did not affect heart rate or blood pressure, and was well tolerated.

CONCLUSIONS

Fasudil up to 80 mg three times daily significantly increased the ischemic threshold of angina patients during exercise with a trend toward increased exercise duration. Further investigation of fasudil doses >80 mg three times daily is indicated.

The involvement of Rho-associated kinases in agonist-dependent contractions of human maternal and placental arteries at term gestation

OBJECTIVE

The purpose of this study was to assess the involvement of rho kinase (ROK) in agonist-dependent contraction of omental, myometrial, and placental arteries of pregnant women at term.

STUDY DESIGN

Wire myography was used to assess if contractions of intact or alpha-toxin-permeabilized arteries obtained from women at elective cesarean section were influenced by the ROK inhibitor Y-27632.

RESULTS

Western blotting indicated the presence of ROKalpha in each of the 3 tissue types. In intact human omental, myometrial, or placental arteries, Y-27632 dose-dependently reduced constrictions to the thromboxane-mimetic U46619. In permeabilized vessels, U46619 induced substantial Ca(2+)-sensitization of contraction that was inhibited by Y27632. The phosphatase inhibitor calyculin A induced a Ca(2+)sensitization of contraction similar to that of U46619 in permeabilized omental arteries that was unaffected by Y-27632, suggesting that ROK may signal via myosin phosphatase in these vessels.

CONCLUSION

These results are the first report of the involvement of ROK in the receptor-coupled constriction of intact and permeabilized arteries from pregnant women.

Therapeutic potential of rho-kinase inhibitors in cardiovascular diseases

Rho-kinase is a signaling molecule that occurs downstream of the small GTPase Rho, which mediates various cellular functions. The Rho/Rho-kinase pathway plays an important role in pathophysiology and progression of various cardiovascular diseases such as hypertension, coronary vasospasm, angina pectoris, and restenosis after percutaneous coronary intervention, all of which are related to arteriosclerosis/atherosclerosis changes of the vasculature. Activation of the Rho/Rho-kinase pathway contributes to inflammatory and proliferative changes of the blood vessels and affects cardiac myocytes. Evidence from in vitro and in vivo studies suggests that Rho-kinase inhibitors have beneficial effects on cardiovascular diseases, particularly arteriosclerosis and coronary vasospasm. Furthermore, activation of the Rho/Rho-kinase pathway contributes to blood pressure regulation via the central sympathetic nervous system. There is evidence to suggest that Rho-kinase is involved in angiotensin II-induced cardiac hypertrophy and endothelial dysfunction, and preliminary data indicate that inhibition of Rho-kinase may be beneficial in vascular disorders such as pulmonary arterial hypertension and erectile dysfunction. Fasudil is currently the only Rho-kinase inhibitor available for clinical use and it is approved in Japan for the prevention of vasospasm in patients with subarachnoid hemorrhage. Emerging clinical data have shown that oral fasudil 80 mg three times daily is effective in preventing myocardial ischemia in patients with stable angina pectoris. Rho-kinase represents a new target for the management of cardiovascular diseases and further studies are needed to define the therapeutic potential of Rho-kinase inhibitors.

Divergent effects of estrogen and nicotine on Rho-kinase expression in human coronary vascular smooth muscle cells

Recent studies have demonstrated that up-regulated Rho-kinase plays an important role in the pathogenesis of coronary arteriosclerosis and vasospasm. We have shown that inflammatory stimuli, such as angiotensin II and interleukin-1beta, up-regulate Rho-kinase expression and activity in human coronary vascular smooth muscle cells, for which intracellular signal transduction mediated by protein kinase C and NF-kappaB is involved. Here, we show that estrogen down-regulates while nicotine up-regulates Rho-kinase and that nicotine counteracts the inhibitory effect of estrogen on angiotensin II-induced Rho-kinase expression. Furthermore, we demonstrated that the intracellular signal transduction of the inhibitory effect of estrogen is mediated by an estrogen receptor. These results demonstrate that inflammatory stimuli up-regulate Rho-kinase, for which estrogen (mediated by an estrogen receptor) and nicotine exert divergent inhibitory and stimulatory effects on the Rho-kinase expression, respectively, and may explain in part why the incidence of arteriosclerotic and vasospastic disorders is increased in postmenopausal women and smokers.

Prostacyclin Does Not Inhibit Rho-Kinase

Primary pulmonary hypertension continues to be a fatal disease. We have recently demonstrated that long-term inhibition of Rho-kinase, an effector of the small GTPase Rho, is effective for the treatment of pulmonary hypertension (PH) in rats and humans. Prostacyclin has been clinically used for the treatment of PH with moderate success. However, it remains to be examined whether Rho-kinase inhibition is involved in its beneficial effects on PH. In an ELISA assay, neither prostacyclin nor its oral analogue, beraprost sodium, inhibited Rho-kinase even at higher concentrations (10(-7) to 10(-5) M, 100 to 10,000 times higher than their clinical concentrations), whereas specific Rho-kinase inhibitors, fasudil and hydroxyfasudil, markedly (approximately 95%) inhibited the Rho-kinase activity at 10(-5) M (near their clinical concentrations). Beraprost sodium did not significantly suppress serotonin-induced vascular smooth muscle cell (VSMC) contractions or Rho-kinase activity of the rat aorta without endothelium, as evaluated by the extent of phosphorylation of the ERM family, a substrate of Rho-kinase, whereas hydroxyfasudil markedly suppressed the VSMC contractions and Rho-kinase activity. These results indicate that prostacyclin lacks direct inhibitory effect on Rho-kinase and suggest that combination therapy with prostacyclin and a Rho-kinase inhibitor could exert further beneficial effects on PH.

Inflammatory stimuli upregulate Rho-kinase in human coronary vascular smooth muscle cells

Recent studies have demonstrated that upregulated Rho-kinase plays an important role in the pathogenesis of arteriosclerosis and vasospasm in both animals and humans. However, little is known about the molecular mechanism(s) involved in the Rho-kinase upregulation. Since inflammatory mechanisms have been implicated in the pathogenesis of arteriosclerosis and vasospasm, we examined whether inflammatory stimuli upregulate Rho-kinase in vitro and in vivo. In cultured human coronary vascular smooth muscle cells (hcVSMC), inflammatory stimuli, such as angiotensin II and interleukin-1beta, increased Rho-kinase expression (at both mRNA and protein levels) and function (as evaluated by the extent of the phosphorylation of the ERM (the ezrin/radixin/moesin) family, substrates of Rho-kinase) in a time- and concentration-dependent manner. The expression of Rho-kinase was inhibited by blockades of protein kinase C (PKC) (by either GF109253 or prolonged treatment with phorbol myristate acetate for 24 h) and an adenovirus-mediated gene transfer of dominant-active Ikappa-B, suggesting an involvement of PKC and NF-kappaB in the intracellular signal transduction pathway for the Rho-kinase expression. Furthermore, coronary vascular lesion formation (characterized by medial thickening and perivascular fibrosis) induced by a long-term administration of angiotensin II was markedly suppressed in NF-kappaB(-/-) mice with reduced expression and activity of Rho-kinase in vivo. These results indicate that the expression and function of Rho-kinase are upregulated by inflammatory stimuli (e.g. angiotensin II and IL-1beta) in hcVSMC with an involvement of PKC and NF-kappaB both in vitro and in vivo.

Cardioprotective mechanisms of Rho-kinase inhibition associated with eNOS and oxidative stress-LOX-1 pathway in Dahl salt-sensitive hypertensive rats

OBJECTIVES

Rho-kinase plays a crucial role in various cellular functions. To elucidate molecular mechanisms of Rho-kinase-mediated cardiovascular remodeling in vivo, we evaluated whether a signaling pathway through Rho is involved, and whether Y-27632, a specific Rho-kinase inhibitor, stimulates endothelial nitric oxide synthase (eNOS) and suppresses the oxidative stress and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) pathway in the left ventricle of Dahl salt-sensitive hypertensive (DS) rats.

METHODS

Y-27632 (3 mg/kg per day) or vehicle were given for 5 weeks, from age 6 weeks to a stage of left ventricular hypertrophy (11 weeks). Age-matched Dahl salt-resistant (DR) rats fed the same diet served as a control group.

RESULTS

Increased left ventricular weight in the hypertrophy stage was significantly ameliorated by Y-27632. Upregulated RhoA protein, Rho-kinase gene expression and myosin light-chain phosphorylation in the hypertrophy stage were suppressed by Y-27632. Increased expression of NAD(P)H oxidase p22phox, p47phox, gp91phox and LOX-1 in DS rats were inhibited by Y-27632. Upregulated protein kinase Cepsilon and p65 nuclear factor-kappaB phosphorylation in DS rats was reduced by Y-27632. In contrast, downregulated eNOS expression in hypertrophy stage was upregulated by Y-27632. Y-27632 effectively inhibited vascular lesion formation, such as medial thickness and perivascular fibrosis, and suppressed transforming growth factor-beta1, type I and III collagen, and fibronectin gene expression.

CONCLUSIONS

Inhibiting the Rho-kinase pathway may play a key role in the cardioprotective effect on cardiovascular remodeling associated with eNOS and the oxidative stress-LOX-1 pathway in DS rats, and may be at least a potential therapeutic strategy for hypertension with cardiac hypertrophy.

Rho/Rho kinase signaling mediates increased basal pulmonary vascular tone in chronically hypoxic rats

Recent evidence suggests that Rho/Rho kinase signaling plays an important role in the sustained vasoconstriction induced by many agonists and is involved in the pathogenesis of systemic vascular diseases. However, little is known about its role in increased vascular tone in hypoxic pulmonary hypertension (PH). The purpose of this study was to examine whether Rho/Rho kinase-mediated Ca2+ sensitization contributed to sustained vasoconstriction and increased vasoreactivity in hypoxic PH in rats. Acute intravenous administration of Y-27632, a Rho kinase inhibitor, nearly normalized the high pulmonary arterial blood pressure and total pulmonary resistance in chronically hypoxic rats. In contrast to nifedipine, Y-27632 also markedly decreased elevated basal vascular tone in hypertensive blood-perfused lungs and isolated pulmonary arteries. Y-27632 and another Rho kinase inhibitor, HA-1077, completely reversed nitro-L-arginine-induced vasoconstriction in physiological salt solution-perfused hypertensive lungs, whereas inhibitors of myosin light chain kinase (ML-9), protein kinase C (GF-109203X), phosphatidylinositol 3-kinase (LY-294002), and tyrosine kinase (tyrphostin A23) caused only partial or no reversal of the vasoconstriction. Vasoconstrictor responses to KCl were augmented in hypertensive physiological salt solution-perfused lungs and pulmonary arteries, and the augmentation was eliminated by Y-27632. These results suggest that Rho/Rho kinase-mediated Ca2+ sensitization plays a central role in mediating sustained vasoconstriction and increased vasoreactivity in hypoxic PH.