Long-term inhibition of Rho-kinase induces a regression of arteriosclerotic coronary lesions in a porcine model in vivo

Menstruation-Related Angina-The Wee Hours

Literature reveals two kinds of menstruation-related anginas-cardiac syndrome X (CSX) and catamenial angina. CSX generally occurs in perimenopausal or postmenopausal women; catamenial angina affects females from puberty to menopause with existing/preexisting or predisposed to coronary artery disease. CSX involves recurring anginal-type retrosternal chest pains during exercise or rest with no significant findings on angiogram. Catamenial angina is menstruation-associated recurrent nonexertional left-sided chest pain alongside diaphoresis, hot flushes, and persistent lethargy. Pathophysiology of both anginas revolve around decreased levels of estrogen. Estrogen is known to act via genomic and nongenomic pathways on cardiomyocytes, endothelial cells, and smooth muscle cells to exert its cardioprotective effect. These cardioprotective effects could be lost during the postovulation phase and at the end of menstruation as well as during perimenopause or menopause owing to the decreased levels of estrogen. Evaluation should begin with a history and physical examination and focus on noninvasive tests such as exercise tolerance test, electrocardiogram, and echocardiogram. Reducing symptoms that cause discomfort and improving quality of life should be the main goal in management. Nitrates along with β blockers and analgesics for pain are the main pharmacologic modalities. Exercise training, smoking cessation, weight loss, and dietary changes are nonpharmacological modalities. Proper awareness and effective communication with patients or caregivers can lead to early diagnosis and treatment initiation.

Molecular Mechanism of Electroacupuncture Regulating Cerebral Arterial Contractile Protein in Rats with Cerebral Infarction Based on MLCK Pathway

OBJECTIVE

To explore the effect of electroacupuncture (EA) intervention on the vasoconstriction of cerebral artery smooth muscle cells after cerebral infarction.

METHODS

Male Wistar rats were randomly divided into 3 groups by a random number table: the model group (n=24), the EA group (n=24), and the normal group (n=6). The model and the EA groups were divided into different time subgroups at 0.5, 1, 3, and 6 h after middle cerebral artery occlusion (MCAO), with 6 rats in each subgroup. MCAO model was established using intraluminal suture occlusion method. The EA group was given EA treatment at acupoint Shuigou (GV 26) instantly after MCAO for 20 min. The contents of cerebrovascular smooth muscle MLCK, the 3 subunits of myosin light chain phosphatase (MLCP) MYPT1, PP1c-δ and M20, as well as myosin-ATPase activity were detected using immunohistochemistry and Western blotting.

RESULTS

The overall expression level of the MYPT1 and PP1c-δ in the model group was significantly higher (P<0.01). After EA intervention, the 0.5 h group expression level was close to that of the normal group (P>0.05), and the other subgroups were still significantly higher than the normal group (P<0.01). After EA intervention, the expression level of each subgroup was significantly lower than the corresponding model group. There was a significant difference between the 0.5 and 1 h subgroups (P<0.01), while a difference was also observed between the 3 and 6 h subgroups (P<0.05). The dynamic change rule gradually increased with the prolongation of infarction time within 6 h after infarction.

CONCLUSION

EA intervention can inhibit contraction of cerebral vascular smooth muscle cells and regulate smooth muscle relaxation by regulating MLCK pathway.

Role of Macrophages and RhoA Pathway in Atherosclerosis

The development, progression, or stabilization of the atherosclerotic plaque depends on the pro-inflammatory and anti-inflammatory macrophages. The influx of the macrophages and the regulation of macrophage phenotype, inflammatory or anti-inflammatory, are controlled by the small GTPase RhoA and its downstream effectors. Therefore, macrophages and the components of the RhoA pathway are attractive targets for anti-atherosclerotic therapies, which would inhibit macrophage influx and inflammatory phenotype, maintain an anti-inflammatory environment, and promote tissue remodeling and repair. Here, we discuss the recent findings on the role of macrophages and RhoA pathway in the atherosclerotic plaque formation and resolution and the novel therapeutic approaches.

Long Noncoding RNAs in the Progression of Atherosclerosis: An Integrated Analysis Based on Competing Endogenous RNA Theory

Long noncoding RNAs (lncRNAs) have been increasingly accepted to function importantly in human diseases by serving as competing endogenous RNAs (ceRNAs). To date, the ceRNA mechanisms of lncRNAs in the progression of atherosclerosis (AS) remain largely unclear. On the basis of ceRNA theory, we implemented a multistep computational analysis to construct an lncRNA-mRNA network for AS progression (ASpLMN). The probe reannotation method and microRNA-target interactions from databases were systematically integrated. Three lncRNAs (GS1-358P8.4, OIP5-AS1, and TUG1) with central topological features in the ASpLMN were firstly identified. By using subnetwork analysis, we then obtained two highly clustered modules and one dysregulated module from the ASpLMN network. These modules, sharing three lncRNAs (GS1-358P8.4, OIP5-AS1, and RP11-690D19.3), were significantly enriched in biological pathways such as regulation of actin cytoskeleton, tryptophan metabolism, lysosome, and arginine and proline metabolism. In addition, random walking in the ASpLMN network indicated that lncRNA RP1-39G22.7 and MBNL1-AS1 may also play an essential role in the pathology of AS progression. The identified six lncRNAs from the aforementioned steps could distinguish advanced- from early-staged AS, with a strong diagnostic power for AS occurrence. In conclusion, the results of this study will improve our understanding about the ceRNA-mediated regulatory mechanisms in AS progression, and provide novel lncRNAs as biomarkers or therapeutic targets for acute cardiovascular events.

Cardiac Lymphatic Dysfunction Causes Drug-Eluting Stent–Induced Coronary Hyperconstricting Responses in Pigs In Vivo

Objective—

We have previously demonstrated that coronary adventitial inflammation plays important roles in the pathogenesis of coronary vasomotion abnormalities, including drug-eluting stent (DES)–induced coronary hyperconstricting responses. Importantly, the adventitia also harbors lymphatic vessels, which may prevent inflammation by transporting extravasated fluid and inflammatory cells. We thus aimed to examine the roles of coronary adventitial lymphatic vessels in the pathogenesis of DES-induced coronary hyperconstricting responses in a porcine model in vivo.

Approach and Results—

We performed 2 experimental studies. In protocol 1, 15 pigs were divided into 3 groups with or without DES and with bare metal stent. Nonstented sites 20 mm apart from stent implantation also were examined. In the protocol 2, 12 pigs were divided into 2 groups with or without lymphatic vessels ligation followed by DES implantation at 2 weeks later (n=6 each). We performed coronary angiography 4 weeks after DES implantation, followed by immunohistological analysis. In protocol 1, the number and the caliber of lymphatic vessels were greater at only the DES edges after 4 more weeks. In protocol 2, coronary hyperconstricting responses were further enhanced in the lymphatic vessels ligation group associated with adventitial inflammation, Rho-kinase activation, and less adventitial lymphatic vessels formation. Importantly, there were significant correlations among these inflammation-related changes and enhanced coronary vasoconstricting responses.

Conclusions—

These results provide evidence that cardiac lymphatic vessel dysfunction plays important roles in the pathogenesis of coronary vasoconstrictive responses in pigs in vivo.

PAR-3 controls endothelial planar polarity and vascular inflammation under laminar flow

Impaired cell polarity is a hallmark of diseased tissue. In the cardiovascular system, laminar blood flow induces endothelial planar cell polarity, represented by elongated cell shape and asymmetric distribution of intracellular organelles along the axis of blood flow. Disrupted endothelial planar polarity is considered to be pro-inflammatory, suggesting that the establishment of endothelial polarity elicits an anti-inflammatory response. However, a causative relationship between polarity and inflammatory responses has not been firmly established. Here, we find that a cell polarity protein, PAR-3, is an essential gatekeeper of GSK3β activity in response to laminar blood flow. We show that flow-induced spatial distribution of PAR-3/aPKCλ and aPKCλ/GSK3β complexes controls local GSK3β activity and thereby regulates endothelial planar polarity. The spatial information for GSK3β activation is essential for flow-dependent polarity to the flow axis, but is not necessary for flow-induced anti-inflammatory response. Our results shed light on a novel relationship between endothelial polarity and vascular homeostasis highlighting avenues for novel therapeutic strategies.

Redox regulation of the actin cytoskeleton and its role in the vascular system

The actin cytoskeleton is critical for form and function of vascular cells, serving mechanical, organizational and signaling roles. Because many cytoskeletal proteins are sensitive to reactive oxygen species, redox regulation has emerged as a pivotal modulator of the actin cytoskeleton and its associated proteins. Here, we summarize work implicating oxidants in altering actin cytoskeletal proteins and focus on how these alterations affect cell migration, proliferation and contraction of vascular cells. Finally, we discuss the role of oxidative modification of the actin cytoskeleton in vivo and highlight its importance for vascular diseases.

Fasudil ameliorates endothelial dysfunction in streptozotocin-induced diabetic rats: a possible role of Rho kinase

Endothelial dysfunction is a major contributor to the pathogenesis of vascular disease in diabetes mellitus and RhoA/Rho-kinase (ROCK) system appears to play a crucial role in this setting. The present study was conducted to investigate the effect of the selective ROCK inhibitor, fasudil, on diabetes-related endothelial dysfunction and elucidated its underlying mechanism(s). Diabetes was induced by a single intraperitoneal injection of streptozotocin (STZ, 50 mg/kg), and fasudil (5 mg/kg per day) was orally administered for 8 weeks. Our results showed that fasudil administration attenuated the increased activity/expression of ROCK (627.5 ± 27 vs. 247.8 ± 19.1) and the NADPH oxidase subunits, NOX2 and p47phox, in diabetic rat aorta. Fasudil could reduce the elevated tumor necrosis factor (TNF)-α (70.2 ± 14.1 vs. 25.3 ± 5.2) and transforming growth factor (TGF-β) levels and restored the deficit in antioxidant level of the diabetic aorta. Additionally, fasudil markedly improved the endothelial dysfunction in the diabetic aorta (73.8 ± 8.1 vs. 47.42 ± 8.69) and corrected the dysregulated endothelial nitric oxide (eNOS) expression. In conclusion, the present study demonstrates that fasudil effectively ameliorates the endothelial dysfunction in STZ-induced diabetic rats through inhibition of the Rho/ROCK pathway and thereby reducing the TNF-α-mediated NADPH oxidase activation.

Lycopene Ameliorates Transplant Arteriosclerosis in Vascular Allograft Transplantation by Regulating the NO/cGMP Pathways and Rho-Associated Kinases Expression

Objective. Transplant arteriosclerosis is considered one of the major factors affecting the survival time of grafts after organ transplantation. In this study, we proposed a hypothesis of whether lycopene can protect grafted vessels through regulating key proteins expression involved in arteriosclerosis. Methods. Allogeneic aortic transplantation was performed using Brow-Norway rats as donors and Lewis rats as recipients. After transplantation, the recipients were divided into two groups: the allograft group and the lycopene group. Negative control rats (isograft group) were also established. Histopathological staining was performed to observe the pathological changes, and the expression levels of Ki-67, caspase-3, Rho-associated kinases, intercellular adhesion molecules (ICAM-1), and eNOS were assessed. Western blotting analysis and real-time PCR were also performed for quantitative analysis. Results. The histopathological staining showed that vascular stenosis and intimal thickening were not evident after lycopene treatment. The Ki-67, ROCK1, ROCK2, and ICAM-1 expression levels were significantly decreased. However, eNOS expression in grafted arteries and plasma cGMP concentration were increased after lycopene treatment. Conclusions. Lycopene could alleviate vascular arteriosclerosis in allograft transplantation via downregulating Rho-associated kinases and regulating key factor expression through the NO/cGMP pathways, which may provide a potentially effective method for transplant arteriosclerosis in clinical organ transplantation.

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.

In vivo treatment of rat arterial adventitia with interleukin‑1β induces intimal proliferation via the JAK2/STAT3 signaling pathway

Previous studies have indicated that adventitial inflammation is involved in the development of atherosclerosis. The aim of this study was to investigate the effect of arterial adventitia inflammation induced by interleukin (IL)-1β on intimal proliferation and the mechanisms involved in this process. The left common carotid artery adventitia of male rats in the experimental and control groups (25 rats/group) was wrapped with agar containing or without a sustained-release suspension of 2.5 µg IL-1β, respectively. Five animals in each group were randomly selected for sacrifice at 2 h, 8 h, 24 h, 48 h, and 1 week post-treatment. Hematoxylin and eosin staining was performed for to analyze the morphology of the adventitia. The expression of janus kinase (JAK)2, signal transducer and activator of transcription (STAT)3, phosphorylated (p-)JAK2 and p-STAT3 were detected by western blot analysis or immunohistochemistry staining. A model of adventitial inflammation was successfully created by wrapping IL-1β around the rat carotid artery. IL-1β treatment induced vascular smooth muscle cell proliferation and migration as well as intimal proliferation. In addition, the expression of p-JAK2 and p-STAT3 increased after IL-1β treatment. Furthermore, an inhibitor of JAK2/STAT3 pathway, AG490, suppressed IL-1β-induced intimal proliferation and phosphorylation of JAK2 and STAT3. Thus, the JAK2/STAT3 signaling pathway is involved in intimal proliferation caused by vascular adventitial inflammation. Inhibiting the JAK2/STAT3 signaling pathway may be a novel method for the clinical treatment of artery atherosclerosis.

Light and Dark of Reactive Oxygen Species for Vascular Function: 2014 ASVB (Asian Society of Vascular Biology)

Vascular-derived hydrogen peroxide (H2O2) serves as an important signaling molecule in the cardiovascular system and contributes to vascular homeostasis. H2O2 is a second messenger, transducing the oxidative signal into biological responses through posttranslational protein modification. The balance between oxidant and antioxidant systems regulates intracellular redox status, and their imbalance causes oxidative or reductive stress, leading to cellular damage in cardiovascular systems. Excessive H2O2 deteriorates vascular functions and promotes vascular disease through multiple pathways. The RhoA/Rho-kinase pathway plays an important role in various fundamental cellular functions, including production of excessive reactive oxygen species, leading to the development of cardiovascular diseases. Rho-kinase (ROCK1 and ROCK2) belongs to the family of serine/threonine kinases and is an important downstream effector of the small GTP-binding protein RhoA. Rho-kinase plays a crucial role in the pathogenesis of vasospasm, arteriosclerosis, ischemia/reperfusion injury, hypertension, pulmonary hypertension, stroke, and heart failure. Thus, Rho-kinase inhibitors may be useful for the treatment of cardiovascular diseases in humans. In this review, we will briefly discuss the roles of vascular-derived H2O2 and review the recent progress in the translational research on the therapeutic importance of the Rho-kinase pathway in cardiovascular medicine.

2015 ATVB Plenary Lecture: translational research on rho-kinase in cardiovascular medicine

Rho-kinase (ROCKs) is an important downstream effector of the small GTP-binding protein Ras homolog gene family member A. There are 2 isoforms of ROCK, ROCK1 and ROCK2, and they have different functions in several vascular components. The Ras homolog gene family member A/ROCK pathway plays an important role in various fundamental cellular functions, including contraction, motility, proliferation, and apoptosis, whereas its excessive activity is involved in the pathogenesis of cardiovascular diseases. For the past 20 years, a series of translational research studies have demonstrated the important roles of ROCK in the pathogenesis of cardiovascular diseases. At the molecular and cellular levels, ROCK upregulates several molecules related to inflammation, thrombosis, and fibrosis. In animal experiments, ROCK plays an important role in the pathogenesis of vasospasm, arteriosclerosis, hypertension, pulmonary hypertension, and heart failure. Finally, at the human level, ROCK is substantially involved in the pathogenesis of coronary vasospasm, angina pectoris, hypertension, pulmonary hypertension, and heart failure. Furthermore, ROCK activity in circulating leukocytes is a useful biomarker for the assessment of disease severity and therapeutic responses in vasospastic angina, heart failure, and pulmonary hypertension. In addition to fasudil, many other ROCK inhibitors are currently under development for various indications. Thus, the ROCK pathway is an important novel therapeutic target in cardiovascular medicine.

[Effect of repeated oral treatment with etoposide on the expression of intestinal P-glycoprotein and oral morphine analgesia]

Currently, the World Health Organization recommends oral administration of opioid analgesics for patients with cancer to treat cancer-related pain from the initial stage of treatment. Furthermore, many anticancer drugs have been newly-developed and approved as oral form. Because of this trend, the chances of drug-drug interactions between anticancer drugs and opioid analgesics during absorption process from the intestine are likely to increase. To investigate these possible drug-drug interactions, we have focused on intestinal P-glycoprotein (P-gp) which regulates the absorption of various substrate drugs administered orally. Previously, we have found that repeated oral treatment with etoposide (ETP), an anticancer drug, attenuates analgesia of oral morphine, a substrate drug for P-gp, by increasing the expression and activity of intestinal P-gp. However, the mechanism by which ETP treatment increases the intestinal P-gp expression and decreases oral morphine analgesia remains unclear. RhoA, a small G-protein, and ROCK, an effector of RhoA, pathway has been attracted attention with regard to their involvement in the regulatory mechanism of the expression and activity of P-gp. Interestingly, this pathway is activated in response to various signaling induced by some anticancer drugs. Furthermore, it has been reported that ezrin/radixin/moesin (ERM) play a key role in the plasma membrane localization of P-gp, and that RhoA/ROCK pathway regulates the activation process of ERM. This review article introduces the result of our previous research as well as recent findings on the involvement of ERM via activation of RhoA/ROCK in the increased expression of intestinal P-gp and decreased oral morphine analgesia induced by repeated oral treatment with ETP.

Rho-kinase inhibition ameliorates metabolic disorders through activation of AMPK pathway in mice

Background

Metabolic disorders, caused by excessive calorie intake and low physical activity, are important cardiovascular risk factors. Rho-kinase, an effector protein of the small GTP-binding protein RhoA, is an important cardiovascular therapeutic target and its activity is increased in patients with metabolic syndrome. We aimed to examine whether Rho-kinase inhibition improves high-fat diet (HFD)-induced metabolic disorders, and if so, to elucidate the involvement of AMP-activated kinase (AMPK), a key molecule of metabolic conditions.

Methods and Results

Mice were fed a high-fat diet, which induced metabolic phenotypes, such as obesity, hypercholesterolemia and glucose intolerance. These phenotypes are suppressed by treatment with selective Rho-kinase inhibitor, associated with increased whole body O₂ consumption and AMPK activation in the skeletal muscle and liver. Moreover, Rho-kinase inhibition increased mRNA expression of the molecules linked to fatty acid oxidation, mitochondrial energy production and glucose metabolism, all of which are known as targets of AMPK in those tissues. In systemic overexpression of dominant-negative Rho-kinase mice, body weight, serum lipid levels and glucose metabolism were improved compared with littermate control mice. Furthermore, in AMPKα2-deficient mice, the beneficial effects of fasudil, a Rho-kinase inhibitor, on body weight, hypercholesterolemia, mRNA expression of the AMPK targets and increase of whole body O₂ consumption were absent, whereas glucose metabolism was restored by fasudil to the level in wild-type mice. In cultured mouse myocytes, pharmacological and genetic inhibition of Rho-kinase increased AMPK activity through liver kinase b1 (LKB1), with up-regulation of its targets, which effects were abolished by an AMPK inhibitor, compound C.

Conclusions

These results indicate that Rho-kinase inhibition ameliorates metabolic disorders through activation of the LKB1/AMPK pathway, suggesting that Rho-kinase is also a novel therapeutic target of metabolic disorders.

Sulforaphane inhibits TNF-α-induced adhesion molecule expression through the Rho A/ROCK/NF-κB signaling pathway

Endothelial dysfunction is an early indicator of cardiovascular diseases. Increased stimulation of tumor necrosis factor-α (TNF-α) triggers the inflammatory mediator secretion of endothelial cells, leading to atherosclerotic risk. In this study, we investigated whether sulforaphane (SFN) affected the expression of intracellular adhesion molecule-1 (ICAM-1) in TNF-α-induced ECV 304 endothelial cells. Our data showed that SFN attenuated TNF-α-induced expression of ICAM-1 in ECV 304 cells. Pretreatment of ECV 304 cells with SFN inhibited dose-dependently the secretion of proinflammatory cytokines, such as interleukin (IL)-1β, IL-6, and IL-8. SFN inhibited TNF-α-induced nuclear factor-κB (NF-κB) DNA binding activity. Furthermore, SFN decreased TNF-α-mediated phosphorylation of IκB kinase (IKK) and IκBα, Rho A, ROCK, ERK1/2, and plasminogen activator inhibitor-1 (PAI-1) levels. Collectively, SFN inhibited the NF-κB DNA binding activity and downregulated the TNF-α-mediated induction of ICAM-1 in endothelial cells by inhibiting the Rho A/ROCK/NF-κB signaling pathway, suggesting the beneficial effects of SFN on suppression of inflammation within the atherosclerotic lesion.

Direct effects of Rho-kinase inhibitor on pial microvessels in rabbits

PURPOSE

Rho-kinase inhibitor is widely used for prevention of cerebral vascular spasm. However, the cerebral pial vascular action of Rho-kinase inhibitor has not been investigated. We therefore evaluated the direct effects of Y-27632, a Rho-kinase inhibitor, on pial microvessels.

METHOD

Experiments were performed on anesthetized rabbits. A closed cranial window was used to visualize the pial microcirculation. After baseline hemodynamic and pial vascular measurements, the cranial window was superfused with four increasing concentrations of Y-27632 (10(-9), 10(-7), 10(-6), 10(-5) mol l(-1); n = 7) dissolved in artificial cerebrospinal fluid for 7 min each. We measured the diameters of pial vessels, mean arterial pressure (MAP), heart rate (HR), and rectal temperature at 7 min after application of each Y-27632 concentration.

RESULTS

MAP, HR, rectal temperature, arterial pH, PaCO2, PaO2, and plasma Na(+), K(+) and glucose concentrations did not change significantly during the experimental period. Y-27632 at 10(-9) to 10(-7) mol l(-1) did not produce any significant change in pial arterioles. Topical application of Y-27632 at 10(-6) and 10(-5) mol l(-1) produced pial large (8.4 ± 5.7 and 19.8 ± 12.7 %) and small (10.1 ± 8.5 and 18.1 ± 12.3 %) arterioles dilation. However, Y-27632 did not produce any change in pial large and small venules.

CONCLUSION

We evaluated the direct effects of Y-27632 on pial microvessels. Y-27632 dilates only pial arterioles in a concentration-dependent manner, and most at a concentration of 10(-5) mol l(-1). Y-27632 is a potent cerebral pial arteriolar dilator but is not a venular dilator.

OxLDL triggers retrograde translocation of arginase2 in aortic endothelial cells via ROCK and mitochondrial processing peptidase

RATIONALE

Increased arginase activity contributes to endothelial dysfunction by competition for l-arginine substrate and reciprocal regulation of nitric oxide synthase (NOS). The rapid increase in arginase activity in human aortic endothelial cells exposed to oxidized low-density lipoprotein (OxLDL) is consistent with post-translational modification or subcellular trafficking.

OBJECTIVE

To test the hypotheses that OxLDL triggers reverse translocation of mitochondrial arginase 2 (Arg2) to cytosol and Arg2 activation, and that this process is dependent on mitochondrial processing peptidase, lectin-like OxLDL receptor-1 receptor, and rho kinase.

METHODS AND RESULTS

OxLDL-triggered translocation of Arg2 from mitochondria to cytosol in human aortic endothelial cells and in murine aortic intima with a concomitant rise in arginase activity. All of these changes were abolished by inhibition of mitochondrial processing peptidase or by its siRNA-mediated knockdown. Rho kinase inhibition and the absence of the lectin-like OxLDL receptor-1 in knockout mice also ablated translocation. Aminoterminal sequencing of Arg2 revealed 2 candidate mitochondrial targeting sequences, and deletion of either of these confined Arg2 to the cytoplasm. Inhibitors of mitochondrial processing peptidase or lectin-like OxLDL receptor-1 knockout attenuated OxLDL-mediated decrements in endothelial-specific NO production and increases in superoxide generation. Finally, Arg2(-/-) mice bred on an ApoE(-/-) background showed reduced plaque load, reduced reactive oxygen species production, enhanced NO, and improved endothelial function when compared with ApoE(-/-) controls.

CONCLUSIONS

These data demonstrate dual distribution of Arg2, a protein with an unambiguous mitochondrial targeting sequence, in mammalian cells, and its reverse translocation to cytoplasm by alterations in the extracellular milieu. This novel molecular mechanism drives OxLDL-mediated arginase activation, endothelial NOS uncoupling, endothelial dysfunction, and atherogenesis.

Rho/Rho-associated coiled-coil forming kinase pathway as therapeutic targets for statins in atherosclerosis

SIGNIFICANCE

The 3-hydroxy-methylglutaryl coenzyme A reductase inhibitors or statins are important therapeutic agents for lowering serum cholesterol levels. However, recent studies suggest that statins may exert atheroprotective effects beyond cholesterol lowering. These so-called "pleiotropic effects" include effects of statins on vascular and inflammatory cells. Thus, it is important to understand whether other signaling pathways that are involved in atherosclerosis could be targets of statins, and if so, whether individuals with "overactivity" of these pathways could benefit from statin therapy, regardless of serum cholesterol level.

RECENT ADVANCES

Statins inhibit the synthesis of isoprenoids, which are important for the function of the Rho/Rho-associated coiled-coil containing kinase (ROCK) pathway. Indeed, recent studies suggest that inhibition of the Rho/ROCK pathway by statins could lead to improved endothelial function and decreased vascular inflammation and atherosclerosis. Thus, the Rho/ROCK pathway has emerged as an important target of statin therapy for reducing atherosclerosis and possibly cardiovascular disease.

CRITICAL ISSUES

Because atherosclerosis is both a lipid and an inflammatory disease, it is important to understand how inhibition of Rho/ROCK pathway could contribute to statins' antiatherosclerotic effects.

FUTURE DIRECTIONS

The role of ROCKs (ROCK1 and ROCK2) in endothelial, smooth muscle, and inflammatory cells needs to be determined in the context of atherogenesis. This could lead to the development of specific ROCK1 or ROCK2 inhibitors, which could have greater therapeutic benefits with less toxicity. Also, clinical trials will need to be performed to determine whether inhibition of ROCKs, with and without statins, could lead to further reduction in atherosclerosis and cardiovascular disease.

Involvement of PtdIns(4,5)P2 in the regulatory mechanism of small intestinal P-glycoprotein expression

Previously, we reported that repeated oral administration of etoposide (ETP) activates the ezrin/radixin/moesin (ERM) scaffold proteins for P-glycoprotein (P-gp) via Ras homolog gene family member A (RhoA)/Rho-associated coiled-coil containing protein kinase (ROCK) signaling, leading to increased ileal P-gp expression. Recent studies indicate that phosphatidyl inositol 4,5-bisphosphate [PtdIns(4,5)P2] regulates the plasma-membrane localization of certain proteins, and its synthase, the type I phosphatidyl inositol 4-phosphate 5-kinase (PI4P5K), is largely controlled by RhoA/ROCK. Here, we examined whether PtdIns(4,5)P2 and PI4P5K are involved in the increased expression of ileal P-gp following the ERM activation by ETP treatment. Male ddY mice (4-week-old) were treated with ETP (10 mg/kg/day, per os, p.o.) for 5 days. Protein-expression levels were measured by either western blot or dot blot analysis and molecular interactions were assessed using immunoprecipitation assays. ETP treatment significantly increased PI4P5K, ERM, and P-gp expression in the ileal membrane. This effect was suppressed following the coadministration of ETP with rosuvastatin (a RhoA inhibitor) or fasudil (a ROCK inhibitor). Notably, the PtdIns(4,5)P2 expression in the ileal membrane, as well as both P-gp and ERM levels coimmunoprecipitated with anti-PtdIns(4,5)P2 antibody, were increased by ETP treatment. PtdIns(4,5)P2 and PI4P5K may contribute to the increase in ileal P-gp expression observed following the ETP treatment, possibly through ERM activation via the RhoA/ROCK pathway.

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.

RhoA localization with caveolin-1 regulates vascular contractions to serotonin

Vascular smooth muscle contraction occurs following an initial response to an increase in intracellular calcium concentration and a sustained response following increases in the sensitivity of contractile proteins to calcium (calcium sensitization). This latter process is regulated by the rhoA/rho kinase pathway and activated by serotonin. In multiple cell types, signaling molecules compartmentalize within caveolae to regulate their activation. We hypothesized that serotonin differentially compartmentalizes rhoA within caveolar versus noncaveolar lipid rafts to regulate sustained vascular contractions. To test this hypothesis, we measured aortic contractions in response to serotonin in wild-type (WT) and cav-1-deficient mice (cav-1 KO). RhoA-dependent contractions in response to serotonin were markedly augmented in arteries from cav-1 KO mice despite a modest reduction in rhoA expression compared with WT. We found that under basal conditions, rhoA in WT arteries was primarily localized within high-density sucrose gradient fractions but temporally shifted to low-density fractions in response to serotonin. In contrast, rhoA in cav-1 KO arteries was primarily in low-density fractions and shifted to high-density fractions in a similar timeframe as that seen in WT mice. We conclude that localization of rhoA to caveolar versus noncaveolar lipid rafts differentially regulates its activation and contractions to rhoA-dependent agonists with greater activation associated with its localization to noncaveolar rafts. Disruption of rhoA localization within caveolae may contribute to increased activation and enhanced vascular contractions in cardiovascular disease.

Immunoliposomal drug-delivery system targeting lectin-like oxidized low-density lipoprotein receptor–1 for carotid plaque lesions in rats

Object

Targeted drug delivery with immunoliposomes has been applied to various in vivo animal models and is newly focused as a novel therapeutic target. Lectin-like oxidized low-density lipoprotein receptor–1 (LOX1) is a potent regulator of systemic atherosclerosis, and the authors focused on its effect on carotid plaques. The authors developed a LOX1-targeted liposomal rho-kinase inhibitor and examined the therapeutic effect on carotid intimal hypertrophy in rats.

Methods

LOX1-targeted rho-kinase inhibitor fasudil-containing liposomes, composed of hydrogenated soy phosphatidylcholine/cholesterol/PEG2000-DSPE, were prepared by conjugating anti-LOX1 antibodies on the surface and by remote loading of fasudil. Carotid intimal hypertrophy was induced by balloon injury, and the drugs were intravenously administered on Day 3 postinjury. The rats were divided into 4 groups: nontreatment, treatment with intravenous fasudil (2 mg), treatment with liposomal fasudil (2 mg), and treatment with LOX1-targeted liposomal fasudil (2 mg). The authors compared intimal hypertrophy, atherosclerotic factor, and matrix metalloproteinase-9 expression among groups.

Results

DiI–labeled LOX1-targeted liposomes were prominently observed in the lesions on Day 7 after the surgery. The intimal thickness was significantly reduced in the LOX1-targeted liposomal fasudil–treated group (mean 81.6 ± 13.9 μm) compared with the other groups (no treatment 105.4 ± 16.8 μm; fasudil treatment 102.4 ± 20.0 μm; and liposomal fasudil treatment 102.8 ± 22.2 μm; p = 0.046). Matrix metalloproteinase-9 expression was also significantly reduced in the LOX1-targeted liposomal fasudil group.

Conclusions

Liposomes conjugated with anti-LOX1 antibody effectively reached carotid artery lesions, and liposomal rho-kinase significantly inhibited intimal hypertrophy. The new liposomal drug delivery system targeting LOX1 may become a therapeutic strategy for atherosclerotic diseases.

The association of pericardial fat with coronary artery plaque index at MR imaging: The Multi-Ethnic Study of Atherosclerosis (MESA)

PURPOSE

To determine the relationship of pericardial fat, which secretes proinflammatory markers that have been implicated in coronary atherosclerosis, with atherosclerotic plaque in an asymptomatic population-based cohort.

MATERIALS AND METHODS

In this institutional review board-approved study, all participants supplied written informed consent. One hundred eighty-three participants (89 women, 94 men; mean age, 61 years ± 9 [standard deviation]) from the community-based Multi-Ethnic Study of Atherosclerosis (MESA) were included. The coronary artery eccentricity (ratio of maximal to minimal coronary artery wall thickness) was determined by using magnetic resonance (MR) imaging and served as an index of plaque burden. The pericardial fat volume was determined by using computed tomography. Linear regression coefficient analysis was used to correlate pericardial fat volume with coronary artery wall thickness and plaque eccentricity.

RESULTS

Pericardial fat volume correlated significantly with degree of plaque eccentricity (P < .05) in both men and women. After adjustments for body mass index (BMI) and waist circumference, traditional risk factors, C-reactive protein level, and coronary artery calcium content, the relationship between pericardial fat and plaque eccentricity remained significant in men (P < .01) but not in women. BMI and waist circumference correlated with degree of plaque eccentricity in the univariate model (P < .05) but not after adjustment for pericardial fat volume or traditional risk factors.

CONCLUSION

Pericardial fat volume, rather than BMI and waist circumference, was more strongly related to plaque eccentricity as a measure of coronary atherosclerotic plaque burden. The results support the proposed role of pericardial fat in association with atherosclerosis.

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.

Rho-associated coiled-coil-forming kinases (ROCKs): potential targets for the treatment of atherosclerosis and vascular disease

ROCKs are important regulators of the actin cytoskeleton. Because changes in the actin cytoskeleton underlie vascular contractility and remodeling, inflammatory cell recruitment, and cell proliferation, it is likely that the Rho/ROCK pathway will play a central role in mediating vascular function. Indeed, increased ROCK activity is observed in cerebral and coronary vasospasm, hypertension, vascular inflammation, arteriosclerosis, and atherosclerosis. Recent experimental and clinical studies suggest that inhibition of ROCK could be a promising target for the treatment of cardiovascular disease. For example, inhibition of ROCK might be the underlying mechanism by which statins or HMG-CoA reductase inhibitors exert their therapeutic benefits beyond cholesterol reduction. In this review we summarize current understanding of the crucial role of RhoA/ROCK pathway in the regulation of vascular function and discuss its therapeutic potential in the treatment of atherosclerosis and vascular disease.

Optimisation of 6-substituted isoquinolin-1-amine based ROCK-I inhibitors

Rho kinase is an important target implicated in a variety of cardiovascular diseases. Herein, we report the optimisation of the fragment derived ATP-competitive ROCK inhibitors 1 and 2 into lead compound 14A. The initial goal of improving ROCK-I potency relative to 1, whilst maintaining a good PK profile, was achieved through removal of the aminoisoquinoline basic centre. Lead 14A was equipotent against both ROCK-I and ROCK-II, showed good in vivo efficacy in the spontaneous hypertensive rat model, and was further optimised to demonstrate the scope for improving selectivity over PKA versus hydroxy Fasudil 3.

Role of the RhoA/Rho-kinase pathway in the regulation of pulmonary vasoconstrictor function

Calcium is the major intracellular messenger that triggers smooth muscle contraction. The study of calcium-binding proteins, such as calmodulin and its downstream effectors, reveals critical regulation of smooth muscle contraction by protein kinases and phosphatases. Moreover, the small GTP-binding protein RhoA and its downstream effector protein, Rho-kinase, have been shown to play a novel role in the regulation of smooth muscle contraction. Studies have shown that the activation of Rho-kinase is involved in the development of endothelial dysfunction, inflammation, restenosis, and increased vascular tone in a number of cardiovascular disorders. Because inhibitors of this pathway promote vasodilation independent of the mechanism that increases vasoconstrictor tone, it is our hypothesis that Rho-kinase is constitutively active in regulating vasoconstrictor tone in the pulmonary and systemic vascular beds. Studies in the literature suggest that the RhoA/Rho-kinase pathway has an important role in the pathogenesis of pulmonary hypertension.

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.

Rho kinase: an important mediator of atherosclerosis and vascular disease

Atherosclerosis is a complex inflammatory process characterized by the cross-talk between excessive inflammation and lipid accumulation. In the past few years, compelling evidence suggests that statins can decrease vascular inflammation and attenuate the development of atherosclerosis through their so-called "pleiotropic effects". These cholesterol-independent effects are predominantly due to their ability to inhibit isoprenoid synthesis. In particular, inhibition of geranylgeranylpyrophosphate synthesis leads to inhibition of Rho and its downstream target, Rho-kinase (ROCK). Thus, one of the beneficial effects of statin therapy could be due to inhibitory effects on ROCK. ROCK is involved in mediating diverse cellular functions such as smooth muscle contraction, cell migration and proliferation. While increased ROCK activity is associated with endothelial dysfunction, cerebral ischemia, coronary vasospasms and metabolic syndrome, the inhibition of ROCK by statins or selective ROCK inhibitors leads to up-regulation of endothelial nitric oxide synthase (eNOS), decreased vascular inflammation, and reduced atherosclerotic plaque formation. This review will focus on the impact of ROCK in cardiovascular disease and its contributory role to vascular inflammation and the atherosclerosis.

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.

Menstruation angina: a case report

Introduction

Menstruation is commonly associated with migraine and irritable bowel but is rarely correlated with angina or myocardial ischaemia. Only a small number of cases have been reported suggesting a link between menstruation and myocardial ischaemic events.

Case presentation

A case of menstruation angina is reported in order to raise awareness of this association. A 47-year-old South Asian woman presented with recurrent chest pains in a monthly fashion coinciding with her menstruations. Each presentation was associated with troponin elevation. Angioplasty failed to resolve her symptoms but she eventually responded to hormonal therapy.

Conclusions

The possibility of menstruation angina should always be taken into account in any female patients from puberty to menopause presenting with recurrent chest pains. This can allow an earlier introduction of hormonal therapy to arrest further myocardial damage.

Pericardial adipose tissue determined by dual source CT is a risk factor for coronary atherosclerosis

OBJECTIVES

Pericardial fat as a visceral fat depot may be involved in the pathogenesis of coronary atherosclerosis. To gain evidence for that concept we sought to investigate the relation of pericardial fat volumes to risk factors, serum adiponectin levels, inflammatory biomarkers, and the quantity and morphology of coronary atherosclerosis.

METHODS AND RESULTS

Using Dual source CT angiography pericardial fat volume and coronary atherosclerosis were assessed simultaneously. Plaques were classified as calcified, mixed, and noncalcified, and the number of affected segments served as quantitative score. Patients with atherosclerotic lesions had significant larger PAT volumes (226 cm3+/-92 cm3) than patients without atherosclerosis (134 cm3+/-56 cm3; P>0.001). No association was found between BMI and coronary atherosclerosis. PAT volumes >300 cm3 were the strongest independent risk factor for coronary atherosclerosis (odds ratio 4.1; CI 3.63 to 4.33) also significantly stronger compared to the Framingham score. We furthermore demonstrated that elevated PAT volumes are significantly associated with low adiponectin levels, low HDL levels, elevated TNF-alpha levels, and hsCRP.

CONCLUSION

In the present study we demonstrated that elevated PAT volumes are associated with coronary atherosclerosis, hypoadiponectinemia, and inflammation and represent the strongest risk factor for the presence of atherosclerosis and may be important for risk stratification and monitoring.

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.

Role of inducible nitric oxide synthase in induction of RhoA expression in hearts from diabetic rats

AIMS

Recent studies from our laboratory demonstrated that increased expression of the small GTP-binding protein RhoA and activation of the RhoA/rho kinase (ROCK) pathway play an important role in the contractile dysfunction associated with diabetic cardiomyopathy in hearts from streptozotocin (STZ)-induced diabetic rats. Nitric oxide (NO) has been reported to be a positive regulator of RhoA expression in vascular smooth muscle, and we have previously found that the expression of inducible NO synthase (iNOS) is increased in hearts from STZ-diabetic rats. Therefore, in this study, we investigated the hypothesis that induction of iNOS positively regulates RhoA expression in diabetic rat hearts.

METHODS AND RESULTS

To determine whether NO and iNOS could increase RhoA expression in the heart, cardiomyocytes from non-diabetic rats were cultured in the presence of the NO donor sodium nitroprusside (SNP) or lipopolysaccharide (LPS) in the absence and presence of the selective iNOS inhibitor, N(6)-(1-iminoethyl)-l-lysine dihydrochloride (L-NIL). In a second study, 1 week after induction of diabetes with STZ, rats were treated with L-NIL (3 mg/kg/day) for 8 more weeks to determine the effect of iNOS inhibition in vivo on RhoA expression and cardiac contractile function. Expression of iNOS was elevated in cardiomyocytes isolated from diabetic rat hearts. Both SNP and LPS increased RhoA expression in non-diabetic cardiomyocytes. The LPS-induced elevation in RhoA expression was accompanied by an increase in iNOS expression and prevented by L-NIL. Treatment of diabetic rats with L-NIL led to a significant improvement in left ventricular developed pressure and rates of contraction and relaxation concomitant with normalization of total cardiac nitrite levels, RhoA expression, and phosphorylation of the ROCK targets LIM (Lin-11, Isl-1, Mec-3) kinase and ezrin/radixin/moesin.

CONCLUSION

These data suggest that iNOS is involved in the increased expression of RhoA in diabetic hearts and that one of the mechanisms by which iNOS inhibition improves cardiac function is by preventing the upregulation of RhoA and its availability for activation.

Cardiovascular effects of a novel potent and highly selective azaindole-based inhibitor of Rho-kinase

BACKGROUND AND PURPOSE

Rho-kinase (ROCK) has been implicated in the pathophysiology of altered vasoregulation leading to hypertension. Here we describe the pharmacological characterization of a potent, highly selective and orally active ROCK inhibitor, the derivative of a class of azaindoles, azaindole 1 (6-chloro-N4-{3,5-difluoro-4-[(3-methyl-1H-pyrrolo[2,3-b]pyridin-4-yl)oxy]-phenyl}pyrimidine-2,4-diamine).

EXPERIMENTAL APPROACH

Pharmacological characterization of azaindole 1 was performed with human recombinant ROCK in vitro. Vasodilator activity was determined using isolated vessels in vitro and different animal models in vivo.

KEY RESULTS

This compound inhibited the ROCK-1 and ROCK-2 isoenzymes with IC50 s of 0.6 and 1.1 nM in an ATP-competitive manner. Although ATP-competitive, azaindole 1 was inactive against 89 kinases (IC50>10 microM) and showed only weak activity against an additional 21 different kinases (IC50=1-10 microM). Only the kinases TRK und FLT3 were inhibited by azaindole 1 in the sub-micromolar range, albeit with IC50 values of 252 and 303 nM, respectively. In vivo, azaindole 1 lowered blood pressure dose-dependently after i.v. administration in anaesthetized normotensive rats. In conscious normotensive and spontaneously hypertensive rats azaindole 1 induced a dose-dependent decrease in blood pressure after oral administration without inducing a significant reflex increase in heart rate. In anaesthetized dogs, azaindole 1 induced vasodilatation with a moderately elevated heart rate.

CONCLUSIONS AND IMPLICATIONS

Azaindole 1 is representative of a new class of selective and potent ROCK inhibitors and is a valuable tool for the elucidation of the role of ROCK in the cardiovascular system.

RhoA Activation Contributes to Sex Differences in Vascular Contractions

Objective— Studies have suggested that sex differences in endothelial function in part account for the lower incidence of cardiovascular disease in premenopausal women compared with men. Less is known about the role of smooth muscle. We hypothesized that signaling mechanisms that regulate calcium sensitivity in vascular muscle also play a role in determining sex differences in contractile function.

Methods and Results— In aorta, concentration-dependent contractions to serotonin were greater in male versus female mice whereas contractions to KCl and U46619 were similar. Nitric oxide or other endothelial-derived factors did not account for the difference in responses to serotonin because inhibition of nitric oxide synthase (NOS) with N G -nitro- l -arginine, genetic deficiency of endothelial NOS, and removal of endothelium increased contractions but did not abolish the enhanced contractions in aorta from males. Contractions in aorta from both males and females were abolished by a serotonergic 5HT 2A receptor antagonist (ketanserin), however there was no sex difference in 5HT 2A receptor expression. Activation of RhoA and Rho-kinase by serotonin was greater in aorta from males compared with females, but this was not related to greater expression of RhoA or Rho-kinase isoforms (ROCK1 and ROCK2). The sex difference in aortic contractions to serotonin was abolished by an inhibitor of Rho-kinase, Y27632.

Conclusion— We conclude that increased contractions to serotonin in aorta from male mice are attributable to differences in RhoA/Rho-kinase activation in smooth muscle independent of differences in the expression of RhoA or Rho-kinase.

Rho-kinase as a novel gene therapeutic target in treatment of cold ischemia/reperfusion-induced acute lethal liver injury: effect on hepatocellular NADPH oxidase system

In the transplant surgery, reactive oxygen species (ROS) from the reperfused tissue cause ischemia-reperfusion injury, resulting in the primary graft failure. We have recently reported that Rho-kinase, an effecter of the small GTPase Rho, plays an important role in the ROS production in the hyperacute phase of reperfusion; however, the sources and mechanisms of the ROS production remain to be elucidated. The aim of this study was to investigate the source of ROS production with a special reference to Rho-kinase to develop a new strategy against ischemia-reperfusion injury. In an in vivo rat model of liver transplantation, Kupffer cells in the graft were depleted using liposome-encapsulated dichloromethylene diphosphonate to examine the source of ROS production. The effect of adenoviral-mediated overexpression of a dominant-negative Rho-kinase (AdDNRhoK) in hepatocytes in the graft was also examined. Kupffer cells were not involved in the ROS production, whereas the AdDNRhoK transfection to hepatocytes significantly suppressed the ROS production. Furthermore, the ROS production was dose-dependently inhibited by apocynin, an NADPH oxidase inhibitor. Expression of DNRhoK also suppressed the release of pro-inflammatory cytokines, and ameliorated the lethal liver injury with a significant prolongation of the survival. These results suggest that the Rho-kinase-mediated pathway plays a crucial role in the ROS production through NADPH oxidase in hepatocytes during the hyperacute phase of reperfusion in vivo. Thus, Rho-kinase in hepatocytes may be a new therapeutic target for the prevention of primary graft failure in liver transplantation.

Development of Rho-kinase inhibitors for cardiovascular medicine

Rho-kinase (ROCK) is one of the downstream effectors of the small G-protein Rho. The Rho-ROCK pathway has an important role in mediating various cellular functions, including contraction, actin cytoskeleton organization, cell adhesion and motility, proliferation, cytokinesis and gene expression, all of which are involved in the pathogenesis of cardiovascular disease. Indeed, vascular smooth muscle cells, endothelial cells, adventitial cells, cardiomyocytes and nerve cells all undergo pathophysiological changes through the ROCK pathway. Abnormal activation of this pathway is associated with the pathogenesis of various cardiovascular diseases such as hypertension, coronary and cerebral vasospasm, restenosis, atherosclerosis, stroke and heart failure, although the roles of the ROCK isoforms (ROCK1 and ROCK2) remain to be elucidated. In this article, we review the information about the therapeutic importance of the ROCK pathway and summarize the current status of the development of ROCK inhibitors.

Acute vasodilator effect of fasudil, a Rho-kinase inhibitor, in monocrotaline-induced pulmonary hypertension in rats

Pulmonary arterial hypertension is a progressive and fatal disease for which Rho-kinase may be substantially involved. In this study, we examined the acute vasodilator effects of fasudil, a Rho-kinase inhibitor, in monocrotaline (MCT)-induced pulmonary hypertension (PH) in rats. Three weeks after a single subcutaneous injection of MCT (60 mg/kg), hemodynamic variables were measured under conscious and free-moving conditions before and after oral administration of fasudil. MCT caused a significant elevation of mean pulmonary arterial pressure (mPAP). Although a low dose of fasudil (3 mg/kg) had no effect on mPAP, a middle dose (10 mg/kg) caused a significant reduction in mPAP without change in mean systemic arterial pressure (mSAP), and a high dose (30 mg/kg) significantly reduced both mPAP and mSAP. Rho-kinase activity was significantly increased by MCT injection in pulmonary arteries but not in the aorta. Fasudil (10 mg/kg) inhibited only the Rho-kinase activity in pulmonary arteries without any effect in the aorta. Plasma concentration of hydroxyfasudil, a metabolite of fasudil, was within its clinical range in humans. These results demonstrate that fasudil exerts effective and selective vasodilatation of pulmonary arteries in rats with MCT-induced PH at a given dose, suggesting its usefulness for the treatment of the fatal disorder.

Progress of the Study of Rho-kinase and Future Perspective of the Inhibitor

Rho-kinase has been identified as one of the effectors of the small GTP-binding protein Rho. Accumulating evidence has demonstrated that the Rho/Rho-kinase pathway plays an important role in various cellular functions, not only in vascular smooth muscle cell (VSMC) contraction but also in VSMC proliferation, cell migration, and gene expression. Two isoforms of Rho-kinase encoded by two different genes have been identified: ROCK1 and ROCK2. These isoforms are ubiquitously expressed, but with preferential expression of ROCK2 in the brain and skeletal muscle. The expression of Rho-kinase itself is mediated by the protein kinase C/NF-kappaB pathway with an inhibitory and stimulatory modulation by estrogen and nicotine, respectively. At the cellular level, Rho-kinase mediates VSMC contraction, stimulates VSMC proliferation and migration, and enhances inflammatory cell motility. Rho-kinase also upregulates various molecules that accelerate inflammation/oxidative stress, thrombus formation, and fibrosis, while it downregulates endothelial nitric oxide synthase and inhibits insulin signaling. Rho-kinase activity regulates major morphogenetic events during embryonic development through cell migration, differentiation, and axis formation. In animal and clinical studies, Rho-kinase has been shown to be substantially involved in the pathogenesis of vasospasm, arteriosclerosis, hypertension, pulmonary hypertension, and ischemia/reperfusion injury. Fasudil, a selective Rho-kinase inhibitor developed in Japan, is effective for the treatment of a wide range of cardiovascular diseases, with reasonable safety. Thus Rho-kinase is an important therapeutic target in cardiovascular medicine. This review summarizes the recent progress in the study of Rho-kinase and addresses future perspectives of Rho-kinase inhibitors.

Rho kinase as potential therapeutic target for cardiovascular diseases: opportunities and challenges

Rho kinase (ROCK) belongs to a family of Ser/Thr protein kinases that are activated via interaction with the small GTP-binding protein RhoA. Growing evidence suggests that RhoA and ROCK participate in a variety of important physiological functions in vasculature including smooth muscle contraction, cell proliferation, cell adhesion and migration, and many aspects of inflammatory responses. As these processes mediate the onset and progression of cardiovascular disease, modulation of the Rho/ROCK signalling pathway is a potential strategy for targeting an array of cardiovascular indications. Two widely employed ROCK inhibitors, fasudil and Y-27632, have provided preliminary but compelling evidence supporting the potential cardiovascular benefits of ROCK inhibition in preclinical animal disease models and in the clinic. This review summarises the molecular biology of ROCK and its biological functions in smooth muscle, endothelium and other vascular tissues. In addition, there will be a focus on recent progress demonstrating the benefits of ROCK inhibition in several animal models of cardiovascular diseases. Finally, recent progress in the identification of novel ROCK inhibitors and challenges associated with their development for clinical use will be discussed.

ROCKs as therapeutic targets in cardiovascular diseases

There is growing evidence that Rho-kinases (ROCKs), the immediate downstream targets of the small guanosine triphosphate-binding protein Rho, may contribute to cardiovascular disease. ROCKs play a central role in diverse cellular functions such as smooth muscle contraction, stress fiber formation and cell migration and proliferation. Overactivity of ROCKs is observed in cerebral ischemia, coronary vasospasm, hypertension, vascular inflammation, arteriosclerosis and atherosclerosis. ROCKs, therefore, may be an important and still relatively unexplored therapeutic target in cardiovascular disease. Recent experimental and clinical studies using ROCK inhibitors such as Y-27632 and fasudil have revealed a critical role of ROCKs in embryonic development, inflammation and oncogenesis. This review will focus on the potential role of ROCKs in cellular functions and discuss the prospects of ROCK inhibitors as emerging therapy for cardiovascular diseases.

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.