Preventive effects of pravastatin on thrombin-triggered vascular responses via Akt/eNOS and RhoA/Rac1 pathways in vivo

Exploring Cutting-Edge Approaches to Potentiate Mesenchymal Stem Cell and Exosome Therapy for Myocardial Infarction

Cardiovascular diseases (CVDs) continue to be a significant global health concern. Many studies have reported promising outcomes from using MSCs and their secreted exosomes in managing various cardiovascular-related diseases like myocardial infarction (MI). MSCs and exosomes have demonstrated considerable potential in promoting regeneration and neovascularization, as well as exerting beneficial effects against apoptosis, remodeling, and inflammation in cases of myocardial infarction. Nonetheless, ensuring the durability and effectiveness of MSCs and exosomes following in vivo transplantation remains a significant concern. Recently, novel methods have emerged to improve their effectiveness and robustness, such as employing preconditioning statuses, modifying MSC and their exosomes, targeted drug delivery with exosomes, biomaterials, and combination therapy. Herein, we summarize the novel approaches that intensify the therapeutic application of MSC and their derived exosomes in treating MI.

Targeting Early Atherosclerosis: A Focus on Oxidative Stress and Inflammation

Atherosclerosis is a chronic vascular inflammatory disease associated to oxidative stress and endothelial dysfunction. Oxidation of low-density lipoprotein (LDL) cholesterol is one of the key factors for the development of atherosclerosis. Nonoxidized LDL have a low affinity for macrophages, so they are not themselves a risk factor. However, lowering LDL levels is a common clinical practice to reduce oxidation and the risk of major events in patients with cardiovascular diseases (CVD). Atherosclerosis starts with dysfunctional changes in the endothelium induced by disturbed shear stress which can lead to endothelial and platelet activation, adhesion of monocytes on the activated endothelium, and differentiation into proinflammatory macrophages, which increase the uptake of oxidized LDL (oxLDL) and turn into foam cells, exacerbating the inflammatory signalling. The atherosclerotic process is accelerated by a myriad of factors, such as the release of inflammatory chemokines and cytokines, the generation of reactive oxygen species (ROS), growth factors, and the proliferation of vascular smooth muscle cells. Inflammation and immunity are key factors for the development and complications of atherosclerosis, and therefore, the whole atherosclerotic process is a target for diagnosis and treatment. In this review, we focus on early stages of the disease and we address both biomarkers and therapeutic approaches currently available and under research.

Adjunctive therapy with statins reduces residual albuminuria/proteinuria and provides further renoprotection by downregulating the angiotensin II-AT1 pathway in hypertensive nephropathy

OBJECTIVES

Blockade of the renin-angiotensin II (Ang II) system by AT1 blockers (ARBs) and angiotensin-converting enzyme inhibitors retards the progression of chronic kidney disease (CKD) by reducing albuminuria/proteinuria. However, many patients with CKD suffer from residual albuminuria/proteinuria, which is an independent risk factor for CKD progression. The aim of the current study is to investigate the effect of pitavastatin, one of the adjunctive agents to ARBs, on the reduction of albuminuria/proteinuria and further renoprotection mediated by telmisartan in spontaneously hypertensive rats.

METHODS AND RESULTS

Forty-two-week-old spontaneously hypertensive rats were grouped randomly and received 8 weeks of treatments with vehicle, telmisartan, pitavastatin or a combination of telmisartan and pitavastatin. Both albuminuria and proteinuria were inhibited significantly in the telmisartan-treated group, but an obviously residual albuminuria was maintained. The combination treatment with telmisartan and pitavastatin displayed a more effective decrease in albuminuria and proteinuria, even to the normal level. Enhanced nephroprotection was also observed in this combination group, which was independent of the cholesterol-lowering effects. Further mechanistic studies revealed that the combination therapy greatly attenuated the expression of intrarenal Ang II and AT1, thereby decreasing the activation of TGF-β-Smad and NF-κB and inhibiting fibrosis and inflammation.

CONCLUSION

Adjunctive therapy with pitavastatin dramatically reduced residual albuminuria/proteinuria and enhanced nephroprotection, likely by downregulating the expression of intrarenal Ang II and AT1. It could be concluded that statins might be a promising adjunctive therapeutic agent to conventional ARB treatment in hypertensive renal damage.

Endothelial Cell Metabolism

Endothelial cells (ECs) are more than inert blood vessel lining material. Instead, they are active players in the formation of new blood vessels (angiogenesis) both in health and (life-threatening) diseases. Recently, a new concept arose by which EC metabolism drives angiogenesis in parallel to well-established angiogenic growth factors (e.g., vascular endothelial growth factor). 6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3-driven glycolysis generates energy to sustain competitive behavior of the ECs at the tip of a growing vessel sprout, whereas carnitine palmitoyltransferase 1a-controlled fatty acid oxidation regulates nucleotide synthesis and proliferation of ECs in the stalk of the sprout. To maintain vascular homeostasis, ECs rely on an intricate metabolic wiring characterized by intracellular compartmentalization, use metabolites for epigenetic regulation of EC subtype differentiation, crosstalk through metabolite release with other cell types, and exhibit EC subtype-specific metabolic traits. Importantly, maladaptation of EC metabolism contributes to vascular disorders, through EC dysfunction or excess angiogenesis, and presents new opportunities for anti-angiogenic strategies. Here we provide a comprehensive overview of established as well as newly uncovered aspects of EC metabolism.

Effects of Nuclear Factor-E2-related factor 2/Heme Oxygenase 1 on splanchnic hemodynamics in experimental cirrhosis with portal hypertension

OBJECTIVE

We explored the effects of Nuclear Factor-E2-related factor 2 (Nrf2) and Heme Oxygenase 1 (HO-1) on splanchnic hemodynamics in portal hypertensive rats.

METHODS

Experimental cirrhosis with portal hypertension was induced by intraperitoneal injection of carbon tetrachloride. The expression of proteins was examined by immunoblotting. Hemodynamic studies were performed by radioactive microspheres. The vascular perfusion system was used to measure the contractile response of mesentery arterioles in rats.

RESULTS

Nrf2 expression in the nucleus and HO-1 expression in cytoplasm was significantly enhanced in portal hypertensive rats. Portal pressure, as well as regional blood flow, increased significantly in portal hypertension and can be blocked by tin protoporphyrin IX. The expression of endogenous nitric oxide synthase and vascular endothelial growth factors increased significantly compared to normal rats, while HO-1 inhibition decreased the expression of these proteins significantly. The contractile response of mesenteric arteries decreased in portal hypertension, but can be partially recovered through tin protoporphyrin IX treatment.

CONCLUSIONS

The expression of Nrf2/HO-1 increased in mesenteric arteries of portal hypertensive rats, which was related to oxidative stress. HO-1was involved in increased portal pressure and anomaly splanchnic hemodynamics in portal hypertensive rats.

Endothelial cell metabolism: A novel player in atherosclerosis? Basic principles and therapeutic opportunities

Atherosclerosis is a leading cause of morbidity and mortality in Western society. Despite improved insight into disease pathogenesis and therapeutic options, additional treatment strategies are required. Emerging evidence highlights the relevance of endothelial cell (EC) metabolism for angiogenesis, and indicates that EC metabolism is perturbed when ECs become dysfunctional to promote atherogenesis. In this review, we overview the latest insights on EC metabolism and discuss current knowledge on how atherosclerosis deregulates EC metabolism, and how maladaptation of deregulated EC metabolism can contribute to atherosclerosis progression. We will also highlight possible therapeutic avenues, based on targeting EC metabolism.

3-Methylcholanthrene/Aryl-Hydrocarbon Receptor-Mediated Hypertension Through eNOS Inactivation

Endothelial nitric oxide synthase (eNOS) modulates vascular blood pressure and is predominantly expressed in endothelial cells and activated through the protein kinase B (Akt/PKB)-dependent pathway. We previously reported that 3-methylcholanthrene (3MC) activates the aryl hydrocarbon receptor (AhR) and reduces PI3K/Akt phosphorylation. This study investigated the mechanism underlying the downregulatory effects of 3-MC on nitric oxide (NO) production occurring through the AhR/RhoA/Akt-mediated mechanism. The mechanism underlying the effects of 3-MC on eNOS activity and blood pressure was examined in vitro and in vivo through genetic and pharmacological approaches. Results indicated that 3-MC modified heat shock protein 90 (HSP90), caveolin-1, dynein, and eNOS mRNA and protein expression through the AhR/RhoA-dependent mechanism in mouse cerebral vascular endothelial cells (MCVECs) and that 3-MC reduced eNOS phosphorylation through the AhR/RhoA-mediated inactivation of Akt1. The upregulation of dynein expression was associated with decreased eNOS dimer formation (eNOS dimer; an activated form of the enzyme). Coimmunoprecipitation assay results indicated that 3-MC significantly reduced the interaction between eNOS and its regulatory proteins, including Akt1 and HSP90, but increased the interaction between eNOS and caveolin-1. Immunofluorescence and Western blot analysis revealed that 3-MC reduced the amount of membrane-bound activated eNOS, and a modified Griess assay revealed that 3-MC concomitantly reduced NO production. However, simvastatin reduced 3-MC-mediated murine hypertension. Our study results indicate that AhR, RhoA, and eNOS have major roles in blood pressure regulation. Statin intervention might provide a potential therapeutic approach for reducing hypertension caused by 3-MC. J. Cell. Physiol. 232: 1020-1029, 2017. © 2016 Wiley Periodicals, Inc.

Evaluation of hepatic vascular endothelial injury during liver storage by molecular detection and targeted contrast-enhanced ultrasound imaging

We hypothesized that lack of the high-energy phosphates during liver storage may potentially cause persistent injury to the vascular endothelium. Biopsies were obtained from livers obtained from beating heart human donors, stored either in the standard storage solution, that is, University of Wisconsin solution (UWS) or Celsior, and examined for various markers related to progressive endothelial injury. The expression of P2Y1 receptor, the major signal transduction machinery for adenosine triphosphate/adenosine diphosphate, decreased in hepatic vascular endothelial cells over time. Despite unaltered endothelial nitric oxide synthase (eNOS) levels, serine1177-phosphorylated eNOS, the active form of eNOS, progressively decreased with time. The production of nitric oxide enzyme decreased with time when liver tissues were examined in vitro. This also coincided with decreased interaction of eNOS with actin nucleating proteins like myristoylated alanine-rich C kinase substrate and Rac1, which plays a role in modulating the cytoskeleton and helps position eNOS in a favorable cytosolic position for active enzymatic activity. Conversely, the interaction of eNOS with caveolin1 was significantly increased 6 H after ex vivo storage. Finally, we demonstrated by targeted contrast-enhanced ultrasound that membrane-bound vascular cell adhesion molecule-1 in the hepatic vascular endothelial cell increased after 6 H of ex vivo storage. Overall, the results of this study provide evidence of a progressive hepatic vascular endothelial injury during the ex vivo storage. This may be a causative factor for ischemic cholangiopathy and delayed graft function post liver transplantation. © 2015 IUBMB Life, 68(1):51-57, 2015.

MEMBRANE TYPE 1-MATRIX METALLOPROTEINASE (MT1-MMP) IDENTIFIED AS A MULTIFUNCTIONAL REGULATOR OF VASCULAR RESPONSES

Membrane type 1-matrix metalloproteinase (MT1-MMP) functions as a signaling molecules in addition to a transmembrane metalloprotease, which degrades interstitial collagens and extracellular matrix components. This review focuses on the multifunctional roles of MT1-MMP as a signaling molecule in vascular responses to pro-atherosclerotic stimuli in the pathogenesis of cardiovascular diseases. First, the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1)-MT1-MMP signaling axis contributes to endothelial dysfunction, which is mediated via small GTP-binding protein RhoA and Rac1 activation. Second, MT1-MMP plays a crucial role in reactive oxygen species (ROS) generation through the activation of receptor for advanced glycation end products (AGEs) in smooth muscle cells, indicating that MT1-MMP may be a therapeutic target for diabetic vascular complications. Third, MT1-MMP is involved in RhoA/Rac1 activation and Ca(2+) signaling in the mechanism of thrombin-stimulated endothelial dysfunction and oxidant stress. Fourth, the inhibition of the MT1-MMP/Akt signaling pathway may be an attractive strategy for treating endothelial disordered hemostasis in the development of vascular diseases linked to TNF-α-induced inflammation. Fifth, MT1-MMP through RAGE induced RhoA/Rac1 activation and tissue factor protein upregulation through NF-κB phosphorylation in endothelial cells stimulated by high-mobility group box-1, which plays a key role in the systemic inflammation. These findings suggest that the MT1-MMP-mediated signaling axis may be a promising target for treating atherosclerosis and subsequent cardiovascular diseases.

Effects of acute and chronic boysenberry intake on blood pressure and endothelial function in spontaneous hypertensive rats

The effects of acute or chronic intake of boysenberry juice or artificial vinegar on blood pressure (BP) and endothelial function were investigated in spontaneous hypertensive rats (SHR). A single administration of boysenberry juice (BJ, equivalent to 0.5 mL/kg body weight) or artificial boysenberry juice vinegar (BJV, equivalent to 0.5 mL BJ and 0.10 g acetic acid/kg body weight) decreased both systolic blood pressure (SBP) and diastolic blood pressure (DBP) significantly. Reductions in SBP of the control group compared with the BJ and BJV groups reached maxima of -16.8±4.3 and -28.4±7.3 mmHg 8 h after administration, respectively. Chronic SBP- and DBP-lowering effects were also observed upon daily feedings of both BJ and BJV at 4 wk. No significant differences were found in SBP or DBP between respective acute and chronic intake of BJ and BJV, except for the decrease in DBP after 4 wk of BJV intake. This suggests that the polyphenol constituents in BJ and BJV likely play a major role in lowering SBP and DBP under these conditions and that acetic acid added to BJ exerts a DBP-lowering effect after 4 wk of BJV intake. The polyphenolic constituents of these beverages might elevate plasma NO concentration via aortic endothelial nitric oxide synthase activation, but the effects of chronic intake on blood pressure might also be at least partly mediated by the renin-angiotensin system. These results may help explain the beneficial effects of boysenberry intake on cardiovascular health, such as reduced blood pressure and improved endothelial function.

Pravastatin improves the impaired nitric oxide-mediated neurogenic and endothelium-dependent relaxation of corpus cavernosum in aged rats

AIM

The aim of this study was to investigate the effect of pravastatin treatment on diminished corpus cavernosum (CC) function associated with aging.

METHODS

Male rats were divided into three groups as adult rats (12-14 weeks old), aged rats (72-80 weeks old) and aged rats given 10 mg/kg/d pravastatin in drinking water for six weeks. Blood pressure was measured by tail-cuff method. Total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, triglycerides and testosterone levels were estimated in blood. Changes in expression levels of endothelial nitric oxide synthase (eNOS), phosphorylated eNOS (p-eNOS) (Ser-1177), neuronal nitric oxide synthase (nNOS), NADPH oxidase subunit gp91(phox), Rho A and Rho kinase (ROCK2) in CC were assessed by immunohistochemistry. Nitric oxide (NO)-mediated endothelium-dependent and neurogenic CC relaxation were evaluated by acetylcholine (ACh, 0.1 nM-100 µM) and electrical field stimulation (EFS; 30 V, 5 ms, 2-32 Hz), respectively.

RESULTS

In aged rats, NO-mediated, both endothelium-dependent and neurogenic CC relaxation, were significantly impaired as compared to adult rats. Besides, eNOS, p-eNOS and nNOS expressions decreased significantly in CC from aged rats, while gp91(phox), RhoA and ROCK2 expressions increased significantly. The diminished relaxation in response to ACh or EFS as well as the changes in expression of these proteins in aged rats were significantly improved by pravastatin treatment.

CONCLUSION

Pravastatin improves NO-mediated CC relaxations of aged rats probably by inhibiting NADPH oxidase/Rho kinase pathways, and this effect does not seem to be associated with lipid lowering effect of this drug.

Dietary supplementation with essential amino acids boosts the beneficial effects of rosuvastatin on mouse kidney

The effects of high-potency statins on renal function are controversial. To address the impact of statins on renal morpho-functional aspects, normotensive young mice were treated with rosuvastatin (Rvs). Moreover, because statins may impair mitochondrial function, mice received either dietary supplementation with an amino acid mixture enriched in essential amino acids (EAAm), which we previously demonstrated to increase mitochondrial biogenesis in muscle or an unsupplemented control diet for 1 month. Mitochondrial biogenesis and function, apoptosis, and insulin signaling pathway events were studied, primarily in cortical proximal tubules. By electron microscopy analysis, mitochondria were more abundant and more heterogeneous in size, with dense granules in the inner matrix, in Rvs- and Rvs plus EAAm-treated animals. Rvs administration increased protein kinase B and endothelial nitric oxide synthase phosphorylation, but the mammalian target of rapamycin signaling pathway was not affected. Rvs increased the expression of sirtuin 1, peroxisome proliferator-activated receptor γ coactivator-1α, cytochrome oxidase type IV, cytochrome c, and mitochondrial biogenesis markers. Levels of glucose-regulated protein 75 (Grp75), B-cell lymphoma 2, and cyclin-dependent kinase inhibitor 1 were increased in cortical proximal tubules, and expression of the endoplasmic reticulum-mitochondrial chaperone Grp78 was decreased. EAAm supplementation maintained or enhanced these changes. Rvs promotes mitochondrial biogenesis, with a probable anti-apoptotic effect. EAAm boosts these processes and may contribute to the efficient control of cellular energetics and survival in the mouse kidney. This suggests that appropriate nutritional interventions may enhance the beneficial actions of Rvs, and could potentially prevent chronic renal side effects.

Simvastatin induces a central hypotensive effect via Ras-mediated signalling to cause eNOS up-regulation

BACKGROUND AND PURPOSE

Clinical studies indicate that statins have a BP-lowering effect in hypercholesterolemic individuals with hypertension. Specifically, statins modulate BP through the up-regulation of endothelial NOS (eNOS) activation in the brain. However, the signalling mechanisms through which statins enhance eNOS activation remain unclear. Therefore, we examined the possible signalling pathways involved in statin-mediated BP regulation in the nucleus tractus solitarii (NTS).

EXPERIMENTAL APPROACH

To investigate the involvement of Ras and other signalling pathways in simvastatin-induced effects on BP, BP and renal sympathetic nerve activity (RSNA) were determined in spontaneously hypertensive rats (SHRs) before and after i.c.v. administration of simvastatin in the absence and presence of a Ras-specific inhibitor (farnesyl thiosalicylic acid, FTS), a geranylgeranyltransferase inhibitor (GGTI-2133), a PI3K inhibitor (LY294002) or a MAPK-ERK kinase (MEK) inhibitor (PD98059).

KEY RESULTS

FTS significantly attenuated the decrease in BP and increased NO evoked by simvastatin and reversed the decrease in basal RSNA induced by simvastatin. Immunoblotting and pharmacological studies showed that inhibition of Ras activity by FTS significantly abolished simvastatin-induced phosphorylation of ERK1/2, ribosomal protein S6 kinase (RSK), Akt and decreased eNOS phosphorylation. Likewise, administration of Akt and ERK1/2 signalling inhibitors, LY294002 and PD98059, attenuated the reduction in BP evoked by simvastatin. Furthermore, i.c.v. simvastatin decreased Rac1 activation and the number of ROS-positive cells in the NTS.

CONCLUSIONS AND IMPLICATIONS

Simvastatin modulates central BP control in the NTS of SHRs by increasing Ras-mediated activation of the PI3K-Akt and ERK1/2-RSK signalling pathways, which then up-regulates eNOS activation.

Atorvastatin enhance efficacy of mesenchymal stem cells treatment for swine myocardial infarction via activation of nitric oxide synthase

BACKGROUND

In a swine model of acute myocardial infarction (AMI), Statins can enhance the therapeutic efficacy of mesenchymal stem cell (MSCs) transplantation. However, the mechanisms remain unclear. This study aims at assessing whether atorvastatin (Ator) facilitates the effects of MSCs through activation of nitric oxide synthase (NOS), especially endothelial nitric oxide synthase (eNOS), which is known to protect against ischemic injury.

METHODS AND RESULTS

42 miniswines were randomized into six groups (n = 7/group): Sham operation; AMI control; Ator only; MSC only, Ator+MSCs and Ator+MSCs+NG-nitrol-L-arginine (L-NNA), an inhibitor of NOS. In an open-heart surgery, swine coronary artery ligation and reperfusion model were established, and autologous bone-marrow MSCs were injected intramyocardium. Four weeks after transplantation, compared with the control group, Ator+MSCs animals exhibited decreased defect areas of both "perfusion" defined by Single-Photon Emission Computed Tomography (-6.2±1.8% vs. 2.0±5.1%, P = 0.0001) and "metabolism" defined by Positron Emission Tomography (-3.00±1.41% vs. 4.20±4.09%, P = 0.0004); Ejection fraction by Magnetic Resonance Imaging increased substantially (14.22±12.8% vs. 1.64±2.64%, P = 0.019). In addition, indices of inflammation, fibrosis, and apoptosis were reduced and survivals of MSCs or MSC-derived cells were increased in Ator+MSCs animals. In Ator or MSCs alone group, perfusion, metabolism, inflammation, fibrosis or apoptosis were reduced but there were no benefits in terms of heart function and cell survival. Furthermore, the above benefits of Ator+MSCs treatment could be partially blocked by L-NNA.

CONCLUSIONS

Atorvastatin facilitates survival of implanted MSCs, improves function and morphology of infarcted hearts, mediated by activation of eNOS and alleviated by NOS inhibitor. The data reveal the cellular and molecular mechanism for anti-AMI therapy with a combination of statin and stem cells.

Mediating effects of aryl-hydrocarbon receptor and RhoA in altering brain vascular integrity: the therapeutic potential of statins

We have demonstrated previously that focal adhesion kinase (FAK)/RhoA alteration by the aryl-hydrocarbon receptor (AhR) agonist 3-methylcholanthrene (3MC) is involved in the antimigratory effects of 3MC in human umbilical vascular endothelial cells. Here, we identified that signaling properties and molecular mechanisms of RhoA/β-catenin were both implicated in alterations to blood-brain barrier integrity. The mechanisms of action were the down-regulation of integrin, the extracellular matrix, and adherens junction stability. PTEN phosphorylation by 3MC-mediated AhR/RhoA activation increased the proteasomal degradation of β-catenin through PKCδ/pGSK3β-mediated β-catenin phosphorylation; the crucial roles of AhR/RhoA in this process were verified by using gain- or loss-of-function experiments. The decrease in β-catenin led to decreased expression of fibronectin and α5β1 integrin. Additionally, protein interactions among FAK, VE-cadherin, vinculin, and β-actin were simultaneously decreased, resulting in adherens junction instability. Novel functional TCF/LEF1 binding sites in the promoter regions of fibronectin and α5/β1 integrin were identified by electrophoretic mobility shift and chromatin immunoprecipitation assays. The results indicate that the binding activities of β-catenin decreased in mouse cerebrovascular endothelial cells treated with 3MC. In addition, simvastatin and pravastatin treatment reversed 3MC-mediated alterations in mouse cerebrovascular endothelial cells by RhoA inactivation, and the in vitro findings were substantiated by an in vivo blood-brain barrier assay. Thus, endothelial barrier dysfunction due to 3MC occurs through AhR/RhoA-mediated β-catenin down-regulation, which is reversed by simvastatin treatment in vivo.

Heparin cofactor II, a serine protease inhibitor, promotes angiogenesis via activation of the AMP-activated protein kinase-endothelial nitric-oxide synthase signaling pathway

We previously clarified that heparin cofactor II (HCII), a serine proteinase inhibitor, exerts various protective actions on cardiovascular diseases in both experimental and clinical studies. In the present study, we aimed to clarify whether HCII participates in the regulation of angiogenesis. Male heterozygous HCII-deficient (HCII(+/-)) mice and male littermate wild-type (HCII(+/+)) mice at the age of 12-16 weeks were subjected to unilateral hindlimb ligation surgery. Laser speckle blood flow analysis showed that blood flow recovery in response to hindlimb ischemia was delayed in HCII(+/-) mice compared with that in HCII(+/+) mice. Capillary number, arteriole number, and endothelial nitric-oxide synthase (eNOS), AMP-activated protein kinase (AMPK), and liver kinase B1 (LKB1) phosphorylation in ischemic muscles were decreased in HCII(+/-) mice. Human purified HCII (h-HCII) administration almost restored blood flow recovery, capillary density, and arteriole number as well as phosphorylation levels of eNOS, AMPK, and LKB1 in ischemic muscles of HCII(+/-) mice. Although treatment with h-HCII increased phosphorylation levels of eNOS, AMPK, and LKB1 in human aortic endothelial cells (HAECs), the h-HCII-induced eNOS phosphorylation was abolished by compound C, an AMPK inhibitor, and by AMPK siRNA. In a similar fashion, tube formation, proliferation, and migration of HAECs were also promoted by h-HCII treatment and were abrogated by pretreatment with compound C. HCII potentiates the activation of vascular endothelial cells and the promotion of angiogenesis in response to hindlimb ischemia via an AMPK-eNOS signaling pathway. These findings suggest that HCII is a novel therapeutic target for treatment of patients with peripheral circulation insufficiency.

Pravastatin normalizes endothelium-derived contracting factor-mediated response via suppression of Rho-kinase signalling in mesenteric artery from aged type 2 diabetic rat

AIM

Although pravastatin has known pleiotropic effects against adverse cardiovascular conditions, little is known about its effects on endothelium-derived contracting factor (EDCF)-mediated signalling. We aimed to determine the effects of pravastatin on the production of and responses to EDCF in superior mesenteric arteries isolated from rats at the chronic stage of type 2 diabetes.

METHODS

Contractions to acetylcholine (ACh) were examined in superior mesenteric artery rings from aged type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats (56-60 weeks old), from control age-matched non-diabetic Long-Evans Tokushima Otsuka (LETO) rats and from pravastatin-treated (10 mg kg(-1) , p.o., daily for 4 weeks) OLETF rats. Mesenteric artery expressions of cyclo-oxygenases (COXs), microsomal-PGE synthases (mPGESs), RhoA and Rho-kinase proteins, and also the level of phosphorylated ezrin, radixin and moesin (PERM), a substrate for Rho-kinase, were detected by Western blotting.

RESULTS

Arteries from OLETF rats exhibited (vs. LETO rats) (1) enhanced ACh-induced EDCF-mediated contractions, which were inhibited by the Rho-kinase inhibitor Y27632, (2) reductions in the ACh-stimulated release of both PGE(2) and superoxide and (3) increased COX-1 and PERM protein expressions. Mesenteric arteries from OLETF rats treated with pravastatin exhibited (vs. untreated OLETF) (1) reduced ACh-induced contraction, (2) suppressed ACh-induced PGE(2) production and superoxide generation and (3) reduced ACh-induced PERM protein expression.

CONCLUSIONS

These results suggest that pravastatin exerts beneficial effects against abnormal EDCF signalling by suppressing Rho-kinase and promoting antioxidant activity in the mesenteric arteries of rats at the chronic stage of type 2 diabetes.

Nitric oxide-donating statin improves multiple functions of circulating angiogenic cells

BACKGROUND AND PURPOSE

Statins, a major component of the prevention of cardiovascular disease, aid progenitor cell functions in vivo and in vitro. Statins bearing a NO-releasing moiety were developed for their enhanced anti-inflammatory/anti-thrombotic properties. Here, we investigated if the NO-donating atorvastatin (NCX 547) improved the functions of circulating angiogenic cells (CACs).

EXPERIMENTAL APPROACH

Circulating angiogenic cells (CACs) were prepared from peripheral blood monocytes of healthy volunteers and type-2 diabetic patients and were cultured in low (LG) or high glucose (HG) conditions, in presence of atorvastatin or NCX 547 (both at 0.1 µM) or vehicle. Functional assays (outgrowth, proliferation, viability, senescence and apoptosis) were performed in presence of the endothelial NOS inhibitor L-NIO, the NO scavenger c-PTIO or vehicle.

KEY RESULTS

Culturing in HG conditions lowered NO in CACs, inhibited outgrowth, proliferation, viability and migration, and induced cell senescence and apoptosis. NCX 547 fully restored NO levels and functions of HG-cultured CACs, while atorvastatin prevented only apoptosis in CACs. The activity of Akt, a pro-survival kinase, was increased by atorvastatin in LG-cultured but not in HG-cultured CACs, whereas NCX 547 increased Akt activity in both conditions. L-NIO partially blunted and c-PTIO prevented NCX 547-induced improvements in CAC functions. Finally, NCX 547 improved outgrowth and migration of CACs prepared from patients with type 2 diabetes.

CONCLUSIONS AND IMPLICATIONS

NCX 547 was more effective than atorvastatin in preserving functions of CACs. This property adds to the spectrum of favourable actions that would make NO-releasing statins more effective agents for treating cardiovascular disease.

The role of RhoA/Rho kinase pathway in endothelial dysfunction

Endothelial dysfunction is a key event in the development of vascular disease, and it precedes clinically obvious vascular pathology. Abnormal activation of the RhoA/Rho kinase (ROCK) pathway has been found to elevate vascular tone through unbalancing the production of vasodilating and vasoconstricting substances. Inhibition of the RhoA/ROCK pathway can prevent endothelial dysfunction in a variety of pathological conditions. This review, based on recent molecular, cellular, and animal studies, focuses on the current understanding of the ROCK pathway and its roles in endothelial dysfunction.

Recent development in pleiotropic effects of statins on cardiovascular disease through regulation of transforming growth factor-beta superfamily

BACKGROUND

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, also known as statins, are a drug class that reduce the level of cholesterol in the blood. As a result, statins are used to suppress the progression of cardiovascular disease. Evidence points to another component of statins involving the non-lipid effects of the drug class in preventing cardiovascular disease. One specific mediator of this action is the transforming growth factor β (TGF-β) superfamily. The TGF-β superfamily consists of proteins that include TGF-β and bone morphogenetic proteins (BMPs). These proteins regulate cellular pathways to mediate effects including immunomodulation, cell cycling, and angiogenesis. One pathway that mediates these effects is Ras. Moreover, within this pathway, different functions are possible depending on the activation of the specific receptor subtype. This review discusses the recent development of the non-lipid effects of statins in preventing cardiovascular disease progression by regulating Ras pathway of the TGF-β superfamily, especially RhoA/ROCK pathway.

METHODS

A systematic PubMed database search of all English-language articles up to 2011 was conducted using the following terms: statin, TGF-β, Ras, ROCK, GGPP, inducible nitric oxide synthase, endothelial nitric oxide synthase, actin filament formation, PPARγ, MMP-2, and human trials.

CONCLUSION

With better understanding of the pathway, various mediators were identified; some of these mediators are important biomarkers producing more specific and accurate assessment of the pleiotropic effects of statins. The review of human trials also highlights that more specific biomarkers are employed in recent studies, and the non-lipid effects on human subjects are more accurately documented. Confirmation of the accuracy of these biomarkers by further large-scale studies and further development of new biomarkers may prove an important path leading to better patient selection for treatment, and thus better cost-effectiveness may be achieved.

Crucial role of membrane type 1 matrix metalloproteinase (MT1- MMP) in RhoA/Rac1-dependent signaling pathways in thrombin- stimulated endothelial cells

AIM

Thrombin induces vascular responses including the promotion of tissue factor (TF) and plasminogen activator inhibitor-1 (PAI-1) protein expression, which is modulated by small GTPases RhoA and Rac1, Ca(2+) signaling and reactive oxygen species (ROS). Recent studies have shown that membrane type 1 matrix metalloproteinase (MT1-MMP) functions not only as a protease but also as a signaling molecule. In this study, we hypothesized that MT1-MMP may mediate RhoA and Rac1 activation and their downstream events in thrombin-stimulated endothelial cells.

METHODS

We used cultured human aortic endothelial cells (HAECs). MT1-MMP was silenced by small interfering RNA (siRNA). RhoA was inhibited by C3 exoenzyme, whereas adenovirus-mediated gene transfection of dominant negative RhoA and Rac1 was used for the inhibition of RhoA and Rac1. RhoA and Rac1 activation was determined by pull-down assays. Intracellular Ca(2+) concentrations ([Ca(2+)](i)) were fluorescently measured by fura-2 assay. NADPH oxidase activity was determined by lucigenin-enhanced chemiluminescence.

RESULTS

Inhibition of RhoA attenuated thrombin-triggered [Ca(2+)](i) increase and TF and PAI-1 expression in HAECs, whereas thrombin-triggered ROS generation and TF and PAI-1 expression were blocked by inhibition of Rac1. Silencing of MT1-MMP attenuated thrombin-triggered RhoA and Rac1 activation, resulting in the attenuation of downstream events including Ca(2+) signaling, NADPH oxidase activity, ROS generation, and TF and PAI-1 expression.

CONCLUSIONS

The present study shows that MT1-MMP mediates the RhoA/Ca(2+) and Rac1/NADPH oxidase-dependent signaling pathways in thrombin-induced vascular responses.