Gallic Acid Inhibits Proliferation and Migration of Smooth Muscle Cells in a Pig In-Stent Restenosis Model

In-stent restenosis (ISR) develops primarily due to neointimal hyperplasia. Gallic acid (GA) has anti-inflammatory, antioxidant, and cardioprotective effects. This study sought to investigate the effects of GA on neointimal hyperplasia and proliferation and migration of vascular smooth muscle cells (VSMCs) in a pig ISR model. In vitro proliferation and migration experiments were confirmed, after VSMCs were treated with platelet-derived growth factor (PDGF-BB) and GA (100 µM) using a 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assay and a scratch wound assay for 24 hours and 48 hours. A bare metal stent (BMS) was implanted in the pig coronary artery to induce ISR with overdilation (1.1-1.2:1), and GA (10 mg/kg/day) was administered for 4 weeks. At the 4-week follow-up, optical coherence tomography (OCT) and histopathological analyses were performed. GA decreased the proliferation of VSMCs by PDGF-BB for 24 hours (89.24±24.56% vs. 170.04±19.98%, p<0.001) and 48 hours (124.87±7.35% vs. 187.64±4.83%, p<0.001). GA inhibited the migration of VSMCs induced by PDGF-BB for 24 hours (26.73±2.38% vs. 65.38±9.73%, p<0.001) and 48 hours (32.96±3.04% vs. 77.04±10.07%, p<0.001). Using OCT, % neointimal hyperplasia was shown to have significantly decreased in the GA group compared with control vehicle group (28.25±10.07% vs. 37.60±10.84%, p<0.001). GA effectively reduced neointimal hyperplasia by inhibiting the proliferation and migration of VSMCs in a pig ISR model. GA could be a potential treatment strategy for reducing ISR after stent implantation.

Circular RNA circSMAD4 regulates cardiac fibrosis by targeting miR-671-5p and FGFR2 in cardiac fibroblasts

Heart failure is a leading cause of death and is often accompanied by activation of quiescent cardiac myofibroblasts, which results in cardiac fibrosis. In this study, we aimed to identify novel circular RNAs that regulate cardiac fibrosis. We applied transverse aortic constriction (TAC) for 1, 4, and 8 weeks in mice. RNA sequencing datasets were obtained from cardiac fibroblasts isolated by use of a Langendorff apparatus and then further processed by use of selection criteria such as differential expression and conservation in species. CircSMAD4 was upregulated by TAC in mice or by transforming growth factor (TGF)-β1 in primarily cultured human cardiac fibroblasts. Delivery of si-circSMAD4 attenuated myofibroblast activation and cardiac fibrosis in mice treated with isoproterenol (ISP). si-circSmad4 significantly reduced cardiac fibrosis and remodeling at 8 weeks. Mechanistically, circSMAD4 acted as a sponge against the microRNA miR-671-5p in a sequence-specific manner. miR-671-5p was downregulated during myofibroblast activation and its mimic form attenuated cardiac fibrosis. miR-671-5p mimic destabilized fibroblast growth factor receptor 2 (FGFR2) mRNA in a sequence-specific manner and interfered with the fibrotic action of FGFR2. The circSMAD4-miR-671-5p-FGFR2 pathway is involved in the differentiation of cardiac myofibroblasts and thereby the development of cardiac fibrosis.

Protocatechuic acid prevents isoproterenol-induced heart failure in mice by downregulating kynurenine-3-monooxygenase

Protocatechuic acid (3,4-dihydroxybenzoic acid) prevents oxidative stress, inflammation and cardiac hypertrophy. This study aimed to investigate the therapeutic effects of protocatechuic acid in an isoproterenol-induced heart failure mouse model and to identify the underlying mechanisms. To establish the heart failure model, C57BL/6NTac mice were given high-dose isoproterenol (80 mg/kg body weight) for 14 days. Echocardiography revealed that protocatechuic acid reversed the isoproterenol-induced downregulation of fractional shortening and ejection fraction. Protocatechuic acid attenuated cardiac hypertrophy as evidenced by the decreased heart-weight-to-body-weight ratio and the expression of Nppb. RNA sequencing analysis identified kynurenine-3-monooxygenase (Kmo) as a potential target of protocatechuic acid. Protocatechuic acid treatment or transfection with short-interfering RNA against Kmo ameliorated transforming growth factor β1-induced upregulation of Kmo, Col1a1, Col1a2 and Fn1 in vivo or in neonatal rat cardiac fibroblasts. Kmo knockdown attenuated the isoproterenol-induced increase in cardiomyocyte size, as well as Nppb and Col1a1 expression in H9c2 cells or primary neonatal rat cardiomyocytes. Moreover, protocatechuic acid attenuated Kmo overexpression-induced increases in Nppb mRNA levels. Protocatechuic acid or Kmo knockdown decreased isoproterenol-induced ROS generation in vivo and in vitro. Thus, protocatechuic acid prevents heart failure by downregulating Kmo. Therefore, protocatechuic acid and Kmo constitute a potential novel therapeutic agent and target, respectively, against heart failure.

Syringic acid mitigates isoproterenol-induced cardiac hypertrophy and fibrosis by downregulating Ereg

Gallic acid has been reported to mitigate cardiac hypertrophy, fibrosis and arterial hypertension. The effects of syringic acid, a derivative of gallic acid, on cardiac hypertrophy and fibrosis have not been previously investigated. This study aimed to examine the effects of syringic acid on isoproterenol‐treated mice and cells. Syringic acid mitigated the isoproterenol‐induced upregulation of heart weight to bodyweight ratio, pathological cardiac remodelling and fibrosis in mice. Picrosirius red staining, quantitative real‐time polymerase chain reaction (qRT‐PCR) and Western blotting analyses revealed that syringic acid markedly downregulated collagen accumulation and fibrosis‐related factors, including Fn1. The results of RNA sequencing analysis of Ereg expression were verified using qRT‐PCR. Syringic acid or transfection with si‐Ereg mitigated the isoproterenol‐induced upregulation of Ereg, Myc and Ngfr. Ereg knockdown mitigated the isoproterenol‐induced upregulation of Nppb and Fn1 and enhancement of cell size. Mechanistically, syringic acid alleviated cardiac hypertrophy and fibrosis by downregulating Ereg. These results suggest that syringic acid is a potential therapeutic agent for cardiac hypertrophy and fibrosis.

Protocatechuic acid attenuates isoproterenol-induced cardiac hypertrophy via downregulation of ROCK1-Sp1-PKCγ axis

Cardiac hypertrophy is an adaptive response of the myocardium to pressure overload or adrenergic agonists. Here, we investigated the protective effects and the regulatory mechanism of protocatechuic acid, a phenolic compound, using a mouse model of isoproterenol-induced cardiac hypertrophy. Our results demonstrated that protocatechuic acid treatment significantly downregulated the expression of cardiac hypertrophic markers (Nppa, Nppb, and Myh7), cardiomyocyte size, heart weight to body weight ratio, cross-sectional area, and thickness of left ventricular septum and posterior wall. This treatment also reduced the expression of isoproterenol-induced ROCK1, Sp1, and PKCγ both in vivo and in vitro. To investigate the mechanism, we performed knockdown and overexpression experiments. The knockdown of ROCK1, Sp1, or PKCγ decreased the isoproterenol-induced cell area and the expression of hypertrophic markers, while the overexpression of Sp1 or PKCγ increased the levels of hypertrophic markers. Protocatechuic acid treatment reversed these effects. Interestingly, the overexpression of Sp1 increased cell area and induced PKCγ expression. Furthermore, experiments using transcription inhibitor actinomycin D showed that ROCK1 and Sp1 suppression by protocatechuic acid was not regulated at the transcriptional level. Our results indicate that protocatechuic acid acts via the ROCK1/Sp1/PKCγ axis and therefore has promising therapeutic potential as a treatment for cardiac hypertrophy.

A model of atherosclerosis using nicotine with balloon overdilation in a porcine

Pigs are important experimental animals for cardiovascular research. Few porcine coronary atherosclerosis models have been developed; however, their induction requires more than six months. We developed a porcine coronary artery atherosclerosis model using nicotine injection with a balloon overdilation. A coronary balloon was placed in the porcine coronary artery and overdilated to induce a mechanical injury. Nicotine was administrated via intramuscular injection every day, and changes in the coronary artery were observed after four weeks. Coronary angiography revealed nicotine injection with a balloon overdilation group showed narrowing of the coronary artery at the injury site. The combination of balloon and nicotine significantly increased the intimal hyperplasia in optical coherence tomography analysis. Proliferated tunica media were noted in the nicotine injection with balloon overdilation groups and lack of collagen was observed in the tunica media at eight weeks. Quantitative analysis showed increased smooth muscle actin alpha (SMA), cluster of differentiation 68 (CD68), and Krüppel-like factor 4 (KLF4) in the nicotine injection with balloon overdilation groups. Immunohistochemistry results showed CD68-positive cells displayed SMA- and KLF4-positive reactivity in the border zone of the intimal hyperplasia. Our results show that nicotine injection with balloon overdilation can induce atherosclerotic lesions within one month, which can serve as an alternative pig animal model for the development of coronary stents.

Selective HDAC8 Inhibition Attenuates Isoproterenol-Induced Cardiac Hypertrophy and Fibrosis via p38 MAPK Pathway

Histone deacetylase (HDAC) expression and enzymatic activity are dysregulated in cardiovascular diseases. Among Class I HDACs, HDAC2 has been reported to play a key role in cardiac hypertrophy; however, the exact function of HDAC8 remains unknown. Here we investigated the role of HDAC8 in cardiac hypertrophy and fibrosis using the isoproterenol-induced cardiac hypertrophy model system.Isoproterenol-infused mice were injected with the HDAC8 selective inhibitor PCI34051 (30 mg kg⁻¹ body weight). Enlarged hearts were assessed by HW/BW ratio, cross-sectional area, and echocardiography. RT-PCR, western blotting, histological analysis, and cell size measurements were performed. To elucidate the role of HDAC8 in cardiac hypertrophy, HDAC8 knockdown and HDAC8 overexpression were also used. Isoproterenol induced HDAC8 mRNA and protein expression in mice and H9c2 cells, while PCI34051 treatment decreased cardiac hypertrophy in isoproterenol-treated mice and H9c2 cells. PCI34051 treatment also reduced the expression of cardiac hypertrophic markers (Nppa, Nppb, and Myh7), transcription factors (Sp1, Gata4, and Gata6), and fibrosis markers (collagen type I, fibronectin, and Ctgf) in isoproterenol-treated mice. HDAC8 overexpression stimulated cardiac hypertrophy in cells, whereas HDAC8 knockdown reversed those effects. HDAC8 selective inhibitor and HDAC8 knockdown reduced the isoproterenol-induced activation of p38 MAPK, whereas HDAC8 overexpression promoted p38 MAPK phosphorylation. Furthermore, p38 MAPK inhibitor SB203580 significantly decreased the levels of p38 MAPK phosphorylation, as well as ANP and BNP protein expression, induced by HDAC8 overexpression.Here we show that inhibition of HDAC8 activity or expression suppresses cardiac hypertrophy and fibrosis. These findings suggest that HDAC8 could be a promising target to treat cardiac hypertrophy and fibrosis by regulating p38 MAPK.

HDAC5 inhibition reduces angiotensin II-induced vascular contraction, hypertrophy, and oxidative stress in a mouse model

Non-specific histone deacetylase (HDAC) inhibition reduces high blood pressure in essential hypertensive animal models. However, the exact HDAC isoforms that play a critical role in controlling hypertension are not known. Here, we investigated the role of HDAC5 in vascular contraction, hypertrophy, and oxidative stress in the context of angiotensin II (Ang II)-induced hypertension. Genetic deletion of HDAC5 and treatment with class IIa HDAC inhibitors (TMP269 and TMP195) prevented Ang II-induced increases in blood pressure and arterial wall thickness. Hdac5-knockout mice were also resistant to the thromboxane A2 agonist (U46619)-induced vascular contractile response. Furthermore, the expression of Rho-associated protein kinase (ROCK) 2 was downregulated in the aortas of Ang II-treated Hdac5-knockout mice. Knockdown of HDAC5, RhoA, or ROCK2 reduced collagen gel contraction, whereas silencing of ROCK1 increased it. VSMC hypertrophy reduced on knocking down HDAC5, ROCK1, and ROCK2. Here we showed that genetic deletion of HDAC5 and pharmacological inhibition of class IIa HDACs ameliorated Ang II-induced ROS generation. Moreover, ROCK1 and ROCK2, the downstream targets of HDAC5, influenced ROS generation. The relative protein levels of HDAC5, ROCK1, and ROCK2 were increased both in the cytoplasm and nuclear fraction in response to Ang II stimulation in vascular smooth muscle cells. Inhibition of HDAC5 expression or activity reduced vascular hypertrophy, vasoconstriction, and oxidative stress in the Ang II-induced hypertension model. These findings indicate that HDAC5 may serve as a potential target in the treatment of hypertension.

Effect of Renal Denervation on Suppression of PVC and QT Prolongation in a Porcine Model of Acute Myocardial Infarction

Background and Objectives

Antiarrhythmic effect of renal denervation (RDN) after acute myocardial infarction (AMI) remains unclear. The goal of this study was to evaluate the effect of RDN on ventricular arrhythmia (VA) after AMI in a porcine model.

Methods

Twenty pigs were randomly divided into 2 groups based on RDN (RDN, n=10; Sham, n=10). After implanting a loop recorder, AMI was induced by occlusion of the middle left anterior descending coronary artery. Catheter-based RDN was performed for each renal artery immediately after creating AMI. Sham procedure used the same method, but a radiofrequency current was not delivered. Electrocardiography was monitored for 1 hour to observe VA. One week later, the animals were euthanized and the loop recorder data were analyzed.

Results

Ventricular fibrillation event rate and the interval from AMI creation to first VA in acute phase were not different between the 2 groups. However, the incidence of premature ventricular complex (PVC) was lower in the RDN than in the Sham. Additionally, RDN inhibited prolongation of the corrected QT (QTc) interval after AMI. The frequency of non-sustained or sustained ventricular tachycardia, arrhythmic death was lower in the RDN group in the early period.

Conclusions

RDN reduced the incidence of PVC, inhibited prolongation of the QTc interval, and reduced VA in the early period following an AMI. These results suggest that RDN might be a therapeutic option in patients with electrical instability after AMI.

Selective inhibition of histone deacetylase 8 improves vascular hypertrophy, relaxation, and inflammation in angiotensin II hypertensive mice

Background

The dysregulation of histone deacetylase (HDAC) protein expression or its enzyme activity is implicated in a variety of diseases. Cardiac HDAC6 and HDAC8 enzyme activity induced by deoxycorticosterone acetate (DOCA) hypertension was attenuated by sodium valproate, a pan-HDAC inhibitor. However, the HDAC6-selective inhibitor, tubastatin A, did not attenuate angiotensin II-induced hypertension. The purpose of this study was to investigate whether PCI34051, an HDAC8-selective inhibitor, can modulate angiotensin II-induced hypertension and its regulatory mechanism.

Methods

An angiotensin II-regulated mouse model was used in this study. Animals received vehicle or PCI34051 (3 mg·kg - ¹·day- ¹) via intraperitoneal injection. Systolic blood pressure was measured by the tail-cuff method. Blood vessel thickness was measured following hematoxylin and eosin staining, VCAM-1 immunohistochemistry was performed in the aortas, and mRNA expression of renin-angiotensin system components, inflammation markers, and NADPH oxidase (Nox) was determined by RT-PCR. The effect of PCI34051 on vasorelaxation was studied in rat aortic rings, and its effect on nitric oxide (NO) production was determined using DAF-FM DA, a fluorescent dye, in human umbilical vascular endothelial cells (HUVECs).

Results

PCI34051 administration reduced systolic blood pressure via downregulation of angiotensin II receptor type 1 (AT1) mRNA expression. PCI34051 treatment attenuated vascular hypertrophy by decreasing E2F3 and GATA6 mRNA expression. Vascular relaxation after PCI34051 treatment was more dependent on vascular endothelial cells and it was blocked by an NO synthase (NOS) inhibitor. In addition, NO production increased in HUVECs after PCI34051 treatment; this was decreased by the NOS inhibitor. The expression of inflammatory molecules and adhesion molecules VCAM-1 and ICAM-1 decreased in the aortas of angiotensin II-infused mice after PCI34051 administration. However, PCI34051 did not affect Nox or its regulatory subunits.

Conclusions

PCI34051 lowered high blood pressure through modulation of arterial remodeling, vasoconstriction, and inflammation in an angiotensin II-induced hypertension model. We suggest that HDAC8 could be a potential therapeutic target for hypertension.

Class I histone deacetylase inhibitor MS-275 attenuates vasoconstriction and inflammation in angiotensin II-induced hypertension

Objective

Non-selective histone deacetylase (HDAC) inhibitors are known to improve hypertension. Here, we investigated the therapeutic effect and regulatory mechanism of the class I HDAC selective inhibitors, MS-275 and RGFP966, in angiotensin (Ang) II-induced hypertensive mice.

Methods and results

MS-275 inhibited the activity of HDAC1, HDAC2, and HDAC3, while RGFP966 weakly inhibited that of HDAC3 in a cell-free system. MS-275 and RGFP966 treatment reduced systolic blood pressure and thickness of the aorta wall in Ang II-induced hypertensive mice. MS-275 treatment reduced aorta collagen deposition, as determined by Masson’s trichrome staining. MS-275 decreased the components of the renin angiotensin system and increased vascular relaxation of rat aortic rings via the nitric oxide (NO) pathway. NO levels reduced by Ang II were restored by MS-275 treatment in vascular smooth muscle cells (VSMCs). However, MS-275 dose (3 mg·kg^-1·day^-1) was not enough to induce NO production in vivo. In addition, MS-275 did not prevent endothelial nitric oxide synthase (eNOS) uncoupling in the aorta of Ang II-induced mice. Treatment with MS-275 failed to inhibit Ang II-induced expression of NADPH oxidase (Nox)1, Nox2, and p47phox. MS-275 treatment reduced proinflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and monocyte chemoattractant protein (MCP)-1, as well as adhesion molecules. Histological analysis showed that Ang II-induced macrophage infiltration was reduced by MS-275 and RGFP966 administration.

Conclusions

Our results indicate that class I HDAC selective inhibitors may be good therapeutic agents for the treatment of hypertension through the regulation of vascular remodeling and vasoconstriction, as well as inflammation.

Gentisic acid prevents the transition from pressure overload-induced cardiac hypertrophy to heart failure

We previously reported that gentisic acid attenuates cardiac hypertrophy and fibrosis in transverse aortic constriction (TAC)-induced cardiac hypertrophy. Here, we examined whether gentisic acid prevents the development of heart failure. Heart failure was induced in mice via chronic TAC. Mice were administered the vehicle, gentisic acid (10 and 100 mg∙kg^-1∙day^-1), or bisoprolol (0.5 mg∙kg^-1∙day^-1) orally for 3 weeks, beginning 3 weeks after TAC. After oral administration of gentisic acid (2000 mg∙kg^-1), no significant differences in organ weight, histology, or analyzed serum and hematological parameters were observed between female mice in the control and gentisic acid-treated groups. Gentisic acid administration inhibited cardiac dysfunction in a dose-dependent manner, and reduced cardiac hypertrophy and fibrosis, as was revealed via western blotting, quantitative real-time PCR, and Masson's trichrome staining. Gentisic acid dose-dependently reduced the expression of fibrosis marker genes, suppressed the renin-angiotensin-aldosterone system, and reduced lung size and pulmonary vascular remodeling. Our data indicate that gentisic acid prevents cardiac hypertrophy, fibrosis, cardiac dysfunction, and pulmonary pathology in TAC-induced heart failure. These findings suggest that supplementation with gentisic acid may provide an advantage in preventing the progression from cardiac hypertrophy to heart failure.

Histone deacetylase inhibitor LMK235 attenuates vascular constriction and aortic remodelling in hypertension

Here, we report that LMK235, a class I and histone deacetylase (HDAC6)‐preferential HDAC inhibitor, reduces hypertension via inhibition of vascular contraction and vessel hypertrophy. Angiotensin II‐infusion mice and spontaneously hypertensive rats (SHRs) were used to test the anti‐hypertensive effect of LMK235. Daily injection of LMK235 lowered angiotensin II‐induced systolic blood pressure (BP). A reduction in systolic BP in SHRs was observed on the second day when SHRs were treated with 3 mg/kg LMK235 every 3 days. However, LMK235 treatment did not affect angiotensin‐converting enzyme 1 and angiotensin II receptor mRNA expression in either hypertensive model. LMK235, acting via the nitric oxide pathway, facilitated the relaxing of vascular contractions induced by a thromboxane A2 agonist in the rat aortic and mesenteric artery ring test. In addition, LMK235 increased nitric oxide production in HUVECs and inhibited the increasing of aortic wall thickness in both animal hypertensive models. LMK235 decreased the enhanced cell cycle‐related genes cyclin D1 and E2F3 in angiotensin II‐infusion mice and restored the decreased p21 expression. In addition, LMK235 suppressed calcium calmodulin‐dependent protein kinase II (CaMKII) α, which is related to vascular smooth muscle cell proliferation. Inhibition or knockdown of HDAC5 blocked the CaMKIIα‐induced cell cycle gene expression. Immunoprecipitation demonstrated that class I HDACs were involved in the inhibition of CaMKII α‐induced HDAC4/5 by LMK235. We suggest that LMK235 should be further investigated for its use in the development of new therapeutic options to treat hypertension via reducing vascular hyperplasia or vasoconstriction.

Gentisic acid attenuates pressure overload-induced cardiac hypertrophy and fibrosis in mice through inhibition of the ERK1/2 pathway

We previously reported that gentisic acid (2,5‐dihydroxybenzoic acid) is the third most abundant phenolic component of Dendropanax morbifera branch extracts. Here, we investigated its effects on cardiac hypertrophy and fibrosis in a mouse model of pressure overload and compared them to those of the beta blocker bisoprolol and calcium channel blocker diltiazem. Cardiac hypertrophy was induced in mice by transverse aortic constriction (TAC). Beginning 2 weeks after this procedure, the mice were given daily intraperitoneal injections of gentisic acid (100 mg/kg/d), bisoprolol (5 mg/kg/d) or diltiazem (10 mg/kg/d) for 3 weeks. Cardiac hypertrophy was evaluated by the heart weight‐to‐body weight ratio, the cardiomyocyte cross‐sectional area after haematoxylin and eosin staining, and echocardiography. Markers of cardiac hypertrophy and fibrosis were tested by reverse transcription‐quantitative real‐time polymerase chain reaction, western blotting and Masson's trichrome staining. The suppressive effects of gentisic acid treatment on TAC‐induced cardiac hypertrophy and fibrosis were comparable to those of bisoprolol administration. Cardiac hypertrophy was reversed and left ventricular septum and posterior wall thickness were restored by gentisic acid, bisoprolol and diltiazem treatment. Cardiac hypertrophic marker gene expression and atrial and brain natriuretic peptide levels were decreased by gentisic acid and bisoprolol, as were cardiac (interstitial and perivascular) fibrosis and fibrosis‐related gene expression. Cardiac hypertrophy‐associated upregulation of the transcription factors GATA4 and Sp1 and activation of extracellular signal‐regulated kinase 1/2 were also negated by these drugs. These results suggest that gentisic acid could serve as a therapeutic agent for cardiac hypertrophy and fibrosis.

Dendropanax morbifera Prevents Cardiomyocyte Hypertrophy by Inhibiting the Sp1/GATA4 Pathway

An extract of Dendropanax morbifera branch exerts antioxidant, anti-inflammatory, antithrombotic, and anticancer activities. The purpose of this study was to investigate the effect of the extract in isoproterenol-induced cardiac hypertrophy. Phalloidin staining showed that treatment with the extract dramatically prevents isoproterenol-induced H9c2 cell enlargement and the expression of cardiac hypertrophic marker genes, including atrial natriuretic peptide (ANP) and B-type brain natriuretic peptide (BNP). Further, pretreatment with the extract decreased isoproterenol-induced GATA4 and Sp1 expression in H9c2 cells. Overexpression of Sp1 induced the expression of GATA4. The forced expression of Sp1 or its downstream target GATA4, as well as the co-transfection of Sp1 and GATA4 increased the expression of ANP, which was decreased by treatment with the extract. To further elucidate the regulation of the Sp1/GATA4-mediated expression of ANP, knockdown experiments were performed. Transfection with small interfering RNAs (siRNAs) for Sp1 or GATA4 decreased ANP expression. The extract did not further inhibit the expression of ANP reduced by the transfection of GATA4 siRNA. Sp1 knockdown did not affect the expression of ANP that was induced by the overexpression of GATA4; however, GATA4 knockdown abolished the expression of ANP that had been induced by Sp1 overexpression. The extract treatment also attenuated the isoproterenol-induced activation of p38 MAPK, ERK1/2, and JNK1. Hesperidin, catechin, 2,5-dihydroxybenzoic acid, and salicylic acid are the main phenolic compounds present in the extract as observed by high performance liquid chromatography. Hesperidin and 2,5-dihydroxybenzoic acid attenuated isoproterenol-induced cardiac hypertrophy. These findings suggest that the D. morbifera branch extract prevents cardiac hypertrophy by downregulating the activation of Sp1/GATA4 and MAPK signaling pathways.

Gallic acid attenuates calcium calmodulin-dependent kinase II-induced apoptosis in spontaneously hypertensive rats

Hypertension causes cardiac hypertrophy and leads to heart failure. Apoptotic cells are common in hypertensive hearts. Ca²⁺/calmodulin‐dependent protein kinase II (CaMKII) is associated with apoptosis. We recently demonstrated that gallic acid reduces nitric oxide synthase inhibition‐induced hypertension. Gallic acid is a trihydroxybenzoic acid and has been shown to have beneficial effects, such as anti‐cancer, anti‐calcification and anti‐oxidant activity. The purpose of this study was to determine whether gallic acid regulates cardiac hypertrophy and apoptosis in essential hypertension. Gallic acid significantly lowered systolic and diastolic blood pressure in spontaneously hypertensive rats (SHRs). Wheat germ agglutinin (WGA) and H&E staining revealed that gallic acid reduced cardiac enlargement in SHRs. Gallic acid treatment decreased cardiac hypertrophy marker genes, including atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), in SHRs. The four isoforms, α, β, δ and γ, of CaMKII were increased in SHRs and were significantly reduced by gallic acid administration. Gallic acid reduced cleaved caspase‐3 protein as well as bax, p53 and p300 mRNA levels in SHRs. CaMKII δ overexpression induced bax and p53 expression, which was attenuated by gallic acid treatment in H9c2 cells. Gallic acid treatment reduced DNA fragmentation and the TUNEL positive cells induced by angiotensin II. Taken together, gallic acid could be a novel therapeutic for the treatment of hypertension through suppression of CaMKII δ‐induced apoptosis.

Gallic acid attenuates pulmonary fibrosis in a mouse model of transverse aortic contraction-induced heart failure

Gallic acid, a trihydroxybenzoic acid found in tea and other plants, attenuates cardiac hypertrophy, fibrosis, and hypertension in animal models. However, the role of gallic acid in heart failure remains unknown. In this study, we show that gallic acid administration prevents heart failure-induced pulmonary fibrosis. Heart failure induced in mice, 8weeks after transverse aortic constriction (TAC) surgery, was confirmed by echocardiography. Treatment for 2weeks with gallic acid but not furosemide prevented cardiac dysfunction in mice. Gallic acid significantly inhibited TAC-induced pathological changes in the lungs, such as increased lung mass, pulmonary fibrosis, and damaged alveolar morphology. It also decreased the expression of fibrosis-related genes, including collagen types I and III, fibronectin, connective tissue growth factor (CTGF), and phosphorylated Smad3. Further, it inhibited the expression of epithelial-mesenchymal transition (EMT)-related genes, such as N-cadherin, vimentin, E-cadherin, SNAI1, and TWIST1. We suggest that gallic acid has therapeutic potential for the treatment of heart failure-induced pulmonary fibrosis.

Expression of Class I and Class II a/b Histone Deacetylase is Dysregulated in Hypertensive Animal Models

Background and Objectives

Dysregulation of histone deacetylase expression and enzymatic activity is associated with a number of diseases. It has been reported that protein levels of histone deacetylase (HDAC)1 and HDAC5 increase during human pulmonary hypertension, and that the enzymatic activity of HDAC6 is induced in a chronic hypertensive animal model. This study investigated the protein expression profiles of class I and II a/b HDACs in three systemic hypertension models.

Subjects and Methods

We used three different hypertensive animal models: (i) Wistar-Kyoto rats (n=8) and spontaneously hypertensive rats (SHR; n=8), (ii) mice infused with saline or angiotensin II to induce hypertension, via osmotic mini-pump for 2 weeks, and (iii) mice that were allowed to drink L-N^G-nitro-L-arginine methyl ester (L-NAME) to induce hypertension.

Results

SHR showed high systolic, diastolic, and mean blood pressures. Similar increases in systolic blood pressure were observed in angiotensin II or L-NAME-induced hypertensive mice. In SHR, class IIa HDAC (HDAC4, 5, and 7) and class IIb HDAC (HDAC6 and 10) protein expression were significantly increased. In addition, a HDAC3 protein expression was induced in SHR. However, in L-NAME mice, class IIa HDAC protein levels (HDAC4, 5, 7, and 9) were significantly reduced. HDAC8 protein levels were significantly reduced both in angiotensin II mice and in SHR.

Conclusion

These results indicate that dysregulation of class I and class II HDAC protein is closely associated with chronic hypertension.

Piceatannol Attenuates Renal Fibrosis Induced by Unilateral Ureteral Obstruction via Downregulation of Histone Deacetylase 4/5 or p38-MAPK Signaling

Piceatannol, a resveratrol metabolite, is a phenolic compound found in red wine and grapes. We investigated the effect of piceatannol on renal fibrosis and histone deacetylase (HDAC) expression in a mouse model of unilateral ureteral obstruction (UUO). Fibrosis was established by UUO and piceatannol was intraperitoneally injected for 2 weeks. Piceatannol suppressed extracellular matrix (ECM) protein deposition including collagen type I and fibronectin as well as connective tissue growth factor (CTGF) and α-smooth muscle actin (α-SMA) in UUO kidneys. However, the expressions of epithelial-mesenchymal transition (EMT) marker genes, such as N-cadherin and E-cadherin, were not changed in the kidneys after UUO. Masson’s trichrome staining and fluorescence immunostaining showed that piceatannol administration attenuated collagen deposition in UUO kidneys. HDAC1, HDAC4, HDAC5, HDAC6, and HDAC10 protein expression was upregulated in UUO kidneys, whereas that of HDAC8 was downregulated. Piceatannol treatment significantly reduced HDAC4 and HDAC5 protein expression. Further, piceatannol attenuated phosphorylation of p38 mitogen-activated protein kinase (p38-MAPK) in UUO kidneys, but not that of transforming growth factor beta1-Smad2/3. These results suggest that class I HDACs and class IIa/b HDACs are involved in renal fibrosis development. Piceatannol may be a beneficial therapeutic agent for treating renal fibrosis via reduction of HDAC4 and HDAC5 protein expression or suppression of the p38-MAPK signaling pathway.

Biomarkers for discrimination between latent tuberculosis infection and active tuberculosis disease

OBJECTIVE

We aimed to determine whether combinations of multiplex cytokine responses could differentiate Mycobacterium tuberculosis (Mtb) infection states.

METHODS

Mtb-specific antigen-induced and unstimulated cytokines were measured by Luminex assay in supernatants of QuantiFERON^® Gold In-Tube assay (QFT) in 48 active pulmonary TB patients (TB), 15 latent TB infection subjects (LTBI), and 13 healthy controls (HCs).

RESULTS

Among the 29 cytokines, eight Mtb antigen-specific biomarkers (GM-CSF, IFN-γ, IL-1RA, IL-2, IL-3, IL-13, IP-10, and MIP-1β) in the Mtb-infected group were significantly different from those of the HCs. Five Mtb-specific biomarkers (EGF, GM-CSF, IL-5, IL-10, and VEGF), two unstimulated biomarkers (TNF-α_[Nil] and VEGF_[Nil]), and one Mtb-specific biomarker ratio (IL-2/IFN-γ) showed significant differences between active TB and LTBI. Three unstimulated biomarkers (IL-8_[Nil], IL-13_[Nil], and VEGF_[Nil]) and 5 Mtb-specific biomarkers (IFN-γ, IL-2, IL-3, IP-10, and VEGF) were significantly different between active TB and non-active TB groups. Combinations of three cytokine biomarkers resulted in the accurate prediction of 92.1-93.7% of Mtb-infected cases and 92.3-100% of HCs, respectively. Moreover, combinations of five biomarkers accurately predicted 90.9-100% of active TB cases and 80-100% of LTBI subjects, respectively. In discriminating between active TB and non-active TB regardless of QFT results, combinations of six biomarkers predicted 79.2-95.8% of active TB cases and 67.9-89.3% of non-active TB subjects.

CONCLUSIONS

Taken together, our data suggest that combinations of whole blood Mtb antigen-dependent cytokines could serve as biomarkers to determine TB disease states. Especially, VEGF is highlighted as a key biomarker for reflecting active TB, irrespective of stimulation.

Activation, Impaired Tumor Necrosis Factor-α Production, and Deficiency of Circulating Mucosal-Associated Invariant T Cells in Patients with Scrub Typhus

BACKGROUND

Mucosal-associated invariant T (MAIT) cells contribute to protection against certain microorganism infections. However, little is known about the role of MAIT cells in Orientia tsutsugamushi infection. Hence, the aims of this study were to examine the level and function of MAIT cells in patients with scrub typhus and to evaluate the clinical relevance of MAIT cell levels.

METHODOLOGY/PRINCIPAL FINDINGS

Thirty-eight patients with scrub typhus and 53 health control subjects were enrolled in the study. The patients were further divided into subgroups according to disease severity. MAIT cell level and function in the peripheral blood were measured by flow cytometry. Circulating MAIT cell levels were found to be significantly reduced in scrub typhus patients. MAIT cell deficiency reflects a variety of clinical conditions. In particular, MAT cell levels reflect disease severity. MAIT cells in scrub typhus patients displayed impaired tumor necrosis factor (TNF)-α production, which was restored during the remission phase. In addition, the impaired production of TNF-α by MAIT cells was associated with elevated CD69 expression.

CONCLUSIONS

This study shows that circulating MAIT cells are activated, numerically deficient, and functionally impaired in TNF-α production in patients with scrub typhus. These abnormalities possibly contribute to immune system dysregulation in scrub typhus infection.

Mucosal-Associated Invariant T Cell Deficiency in Chronic Obstructive Pulmonary Disease

Mucosal-associated invariant T (MAIT) cells have been reported to play an important role in mucosal immunity. However, little is known about the roles of MAIT cells in chronic obstructive pulmonary disease (COPD). The aims of this study were to examine the levels of circulating MAIT cells and their subsets in COPD patients and to investigate the potential relationship between clinical parameters and MAIT cell levels. Forty-five COPD patients and 57 healthy control subjects were enrolled in the study. Circulating MAIT cells and their subset levels in the peripheral blood were measured by flow cytometry. Disease grades were classified according to the GOLD criteria for the assessment of severity of COPD. Circulating MAIT cell levels were found to be significantly reduced in COPD patients. In particular, this MAIT cell deficiency was more prominent in CD8+ and double-negative T cell subsets. Interestingly, elevated serum C-reactive protein level and reduced FEV1/FVC ratio were associated with MAIT cell deficiency in COPD patients. Furthermore, the circulating MAIT levels were found to be significantly lower in patients with moderate to severe COPD than in patients with mild COPD. Our data shows that MAIT cells are numerically deficient in the peripheral blood of patients with COPD. In addition, this MAIT cell deficiency was found to reflect inflammatory activity and disease severity. These findings provide important information for monitoring the changes in MAIT cell levels and for predicting the prognosis during the disease course.

Tubastatin A suppresses renal fibrosis via regulation of epigenetic histone modification and Smad3-dependent fibrotic genes

Inflammation and fibrosis are implicated in the pathogenesis of hypertensive kidney damage. We previously demonstrated that a nonspecific histone deacetylase (HDAC) inhibitor attenuates cardiac fibrosis in deoxycorticosterone acetate-salt hypertensive rats, which induces HDAC6 protein and enzymatic activity. However, the HDAC inhibitor's effect and mechanism have not yet been demonstrated. We sought to determine whether an HDAC6-selective inhibitor could treat hypertension and kidney damage in angiotensin II-infused mice. Hypertension was induced by infusion of ANG in mice. Tubastatin A, an HDAC6 selective inhibitor, did not regulate blood pressure. Hypertensive stimuli enhanced the expression of HDAC6 in vivo and in vitro. We showed that the inhibition of HDAC6 prevents fibrosis and inflammation as determined by quantitative real-time PCR, western blot, and immunohistochemistry. Small interfering RNA (siRNA) against HDAC6 or Smad3 attenuated hypertensive stimuli-induced fibrosis and inflammation, whereas Smad2 siRNA failed to inhibit fibrosis. Interestingly, the combination of the HDAC6 inhibitor and Smad3 knockdown synergistically blocked transforming growth factor β (TGF-β) or ANG-induced fibrosis. We also demonstrated for the first time, to our knowledge, that acetylation of collagen type I can be regulated by HDAC6/p300 acetyltransferase. The chromatin immunoprecipitation assay revealed that the HDAC6 inhibitor suppressed TGF-β-induced acetylated histone H4 or phospho-Smad2/3 to Smad3 binding elements in the fibrosis-associated gene promoters including collagen type I. These results suggest that HDAC6 may be a valuable therapeutic target for the treatment of hypertension-induced kidney fibrosis and inflammation.

Reliable femoral chronic total occlusion model using a thin biodegradable polymer coated copper stent in a porcine model

Chronic total occlusions (CTOs) are common in patients with peripheral arterial disease (PAD). This study aimed to examine the feasibility and reliability of a CTO induced by a thin biodegradable polymer (polyglycolic acid) coated copper stent in a porcine femoral artery. Novel thin biodegradable polymer coated copper stents (9 mm long) were crimped on an angioplasty balloon (4.5 mm diameter × 12 mm length) and inserted into the femoral artery. Histopathologic analysis was performed 35 days after stenting. In five of six stented femoral arteries, severe in-stent restenosis and total occlusion with collateral circulation were observed without adverse effects such as acute stent thrombosis, leg necrosis, or death at 5 weeks. Fibrous tissue deposition, small vascular channels, calcification, and inflammatory cells were observed in hematoxylin-eosin, Carstair's, and von Kossa tissue stains; these characteristics were similar to pathological findings associated with CTOs in humans. The neointima volume measured by micro-computed tomography was 93.9 ± 4.04 % in the stented femoral arteries. CTOs were reliably induced by novel thin biodegradable polymer coated copper stents in porcine femoral arteries. Successful induction of CTOs may provide a practical understanding of their formation and application of an interventional device for CTO treatment.

Sulforaphane suppresses cardiac hypertrophy by inhibiting GATA4/GATA6 expression and MAPK signaling pathways

SCOPE

Sulforaphane (SFN) is a naturally occurring isothiocynate compound found in cruciferous vegetables. Here, we report the effect of SFN on cardiac hypertrophy and propose an underlying mechanism.

METHODS AND RESULTS

SFN suppresses cardiomyocyte hypertrophy induced by hypertrophic stimuli in vitro and in vivo. SFN suppresses the expression of fetal genes, including atrial natriuretic peptide, brain natriuretic peptide, and beta myosin heavy chain. We used an siRNA technique and atrial natriuretic peptide promoter with mutated GATA binding sites to demonstrate that SFN mediates cardiac hypertrophy by modulating transcription factors GATA4/6.

CONCLUSION

These results suggest that SFN has the potential to prevent cardiac hypertrophy by downregulating GATA4/6 and mitogen-activated protein kinase signaling pathways.

Mucosal-associated invariant T cell deficiency in systemic lupus erythematosus

Mucosal-associated invariant T (MAIT) cells contribute to protection against certain microorganism infections and play an important role in mucosal immunity. However, the role of MAIT cells remains enigmatic in autoimmune diseases. In this study, we examined the level and function of MAIT cells in patients with rheumatic diseases. MAIT cell, cytokine, and programmed death-1 (PD-1) levels were measured by flow cytometry. Circulating MAIT cell levels were significantly reduced in systemic lupus erythematosus (SLE) and rheumatoid arthritis patients. In particular, this MAIT cell deficiency was more prominent in CD8(+) and double-negative T cell subsets, and significantly correlated with disease activity, such as SLE disease activity index and 28-joint disease activity score. Interestingly, MAIT cell frequency was significantly correlated with NKT cell frequency in SLE patients. IFN-γ production in MAIT cells was impaired in SLE patients, which was due to an intrinsic defect in the Ca(2+)/calcineurin/NFAT1 signaling pathway. In SLE patients, MAIT cells were poorly activated by α-galactosylceramide-stimulated NKT cells, thereby showing the dysfunction between MAIT cells and NKT cells. Notably, an elevated expression of PD-1 in MAIT cells and NKT cells was associated with SLE. In rheumatoid arthritis patients, MAIT cell levels were significantly higher in synovial fluid than in peripheral blood. Our study primarily demonstrates that MAIT cells are numerically and functionally deficient in SLE. In addition, we report a novel finding that this MAIT cell deficiency is associated with NKT cell deficiency and elevated PD-1 expression. These abnormalities possibly contribute to dysregulated mucosal immunity in SLE.

miR-18a-5p MicroRNA Increases Vascular Smooth Muscle Cell Differentiation by Downregulating Syndecan4

Background and Objectives

Differentiation and de-differentiation of vascular smooth muscle cells (VSMCs) are important events in atherosclerosis and restenosis after angioplasty. MicroRNAs are considered a key regulator in cellular processes such as differentiation, proliferation, and apoptosis. Here, we report the role of new miR-18a-5p microRNA and its downstream target genes in VSMCs and in a carotid balloon injury model.

Materials and Methods

Expression of miR-18a-5p and its candidate genes was examined in VSMCs and in a carotid artery injury model by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and microRNA microarray analysis. VSMC differentiation marker genes including smooth muscle (SM) α-actin and SM22α were determined by Western blot, qRT-PCR, and a SM22α promoter study. Gene overexpression or knockdown was performed in VSMCs.

Results

miR-18a-5p was upregulated in the rat carotid artery at the early time after balloon injury. Transfection of the miR-18a-5p mimic promoted the VSMC differentiation markers SM α-actin and SM22α. In addition, miR-18a-5p expression was induced in differentiated VSMCs, whereas it decreased in de-differentiated VSMCs. We identified syndecan4 as a downstream target of miR-18-5p in VSMCs. Overexpression of syndecan4 decreased Smad2 expression, whereas knockdown of syndecan4 increased Smad2 expression in VSMCs. Finally, we showed that Smad2 induced the expression of VSMC differentiation marker genes in VSMCs.

Conclusion

These results indicate that miR-18a-5p is involved in VSMC differentiation by targeting syndecan4.

Piceatannol attenuates cardiac hypertrophy in an animal model through regulation of the expression and binding of the transcription factor GATA binding factor 6

Piceatannol is found in grapes, passion fruit, and Japanese knotweed. Piceatannol pretreatment suppresses cardiac hypertrophy induced by isoproterenol as assessed by heart weight/body weight ratio, cross-sectional area, and expression of hypertrophic markers. The anti-hypertrophic effect of piceatannol in rat neonatal cardiomyocytes is the same as that in vivo. Piceatannol inhibits lentiviral-GATA6-induced cardiomyocyte hypertrophy. Furthermore, piceatannol reduces the interaction between GATA4 and GATA6 as well as the DNA-binding activity of endogenous GATA6 in the ANP promoter. Our results suggest that piceatannol may be a novel therapeutic agent for the prevention of cardiac hypertrophy.

Abstract 071: Estrogen-related Receptor Gamma Induces Cardiac Hypertrophy By Activating Gata4

Introduction— Estrogen-related receptor gamma (ERRγ) is an orphan nuclear receptor that has biological roles mainly in metabolism and it controls metabolic switching in perinatal heart. In adult heart diseases, however, the functional roles of ERRγ have not yet been elucidated.

Hypothesis— In the present study, we aimed to characterize the role of ERRγ in cardiac hypertrophy. Here we show that ERRγ provokes cardiac hypertrophy by inducing GATA4 and that its inverse agonist, GSK-5182, prevents cardiac hypertrophy.

Methods and Results— The functional roles of ERRγ in association with development of cardiac hypertrophy were examined in primarily cultured cardiomyocytes, in animal models, and in heart samples from human hypertrophic cardiomyopathy patients. ERRγ expression was increased in hearts obtained from human hypertrophic cardiomyopathy patients and in both agonist-induced cellular models and aortic banding-induced animal models of cardiac hypertrophy. Transgenic overexpression in mouse heart as well as forced expression of ERRγ in cardiomyocytes induced hypertrophic phenotypes. Knock-down of ERRγ blocked agonist-induced hypertrophic phenotypes. ERRγ directly bound to the proximal ERR-responsive element in the GATA4 promoter in a sequence-specific manner and thereby induced transcription. ERRγ-induced hypertrophy was blocked by inhibition of GATA4. GSK-5182 completely blocked cardiac hypertrophy in cardiomyocytes. It also prevented aortic banding-induced cardiac hypertrophy and fibrosis in mouse heart.

Conclusion— These findings demonstrate a novel ERRγ/GATA4 signal cascade in the development of cardiac hypertrophy and suggest GSK-5182 as a possible therapeutic.

HDAC inhibition suppresses cardiac hypertrophy and fibrosis in DOCA-salt hypertensive rats via regulation of HDAC6/HDAC8 enzyme activity

Background : Inhibition of histone deacetylase (HDAC) was reported to suppress cardiac hypertrophy and fibrosis in various hypertrophic animal models. However, the HDAC expression profile and HDAC enzyme activity have not yet been investigated in DOCA-salt hypertensive rats. Methods : Unilaterally nephrectomized rats were implanted with DOCA strips. DOCA-salt rats then received a control diet with vehicle or valproate. We measured the expression of cardiac hypertrophic markers, class I HDACs, class II HDACs, fibrosis, and HDAC enzyme activity. Results : Here we report that sodium valproate inhibits the cardiac hypertrophy accompanied by fibrosis in the heart of chronic hypertensive rats. We show that expression of GATA6 and HDAC6 is upregulated in DOCA-salt hypertension. In addition, HDAC6 and HDAC8 enzyme activity is attenuated by sodium valproate. Conclusion : These results suggest that a novel HDAC6- and HDAC8-selective inhibitor is needed to treat or prevent pathological cardiac hypertrophy. © 2013 S. Karger AG, Basel.

B cell translocation gene, a direct target of miR-142-5p, inhibits vascular smooth muscle cell proliferation by down-regulating cell cycle progression

Vascular smooth muscle cell (VSMC) proliferation plays a key role in neointimal hyperplasia and restenosis. Here we report the role of the microRNA miR-142-5p and its downstream target genes on the proliferation of cultured VSMCs. miR-142-5p promoted VSMC proliferation by down-regulating B cell translocation gene 3 (BTG3). We found that BTG3 inhibited the expression of cell cycle regulatory genes and cell growth. As shown by luciferase reporter assay, miR-142-5p bound directly to the 3'-untranslated region of BTG3. Overexpression of miR-142-5p induced expression of cell cycle regulatory genes. Thus, BTG3, a novel, direct target of miR-142-5p, negatively regulates VSMC proliferation.

The microRNA miR-132 targets Lrrfip1 to block vascular smooth muscle cell proliferation and neointimal hyperplasia

OBJECTIVE

The proliferation and remodeling of vascular smooth muscle cells (VSMCs) is an important pathological event in atherosclerosis and restenosis. Here we report that microRNA-132 (miR-132) blocks vascular smooth muscle cells (VSMC) proliferation by inhibiting the expression of LRRFIP1 [leucine-rich repeat (in Flightless 1) interacting protein-1].

METHODS AND RESULTS

MicroRNA microarray revealed that miR-132 was upregulated in the rat carotid artery after catheter injury, which was further confirmed by quantitative real-time RT-PCR. Transfection of a miR-132 mimic significantly inhibited the proliferation of VSMCs, whereas transfection of a miR-132 antagomir increased it. miR-132 mimic inhibited VSMC migration and induced apoptosis. miR-132 mimic increased the protein amounts of both p27 and smooth muscle (SM) α-actin, whereas it decreased SM α-actin and Bcl2. Bioinformatics showed that LRRFIP1 is a target candidate of miR-132. miR-132 down-regulated luciferase activity driven by a vector containing the 3'-untranslated region of Lrrfip1 in a sequence-specific manner. LRRFIP1 induced VSMC proliferation and increased phosphorylation of ERK. Immunohistochemical analysis revealed that Lrrfip1 was clearly expressed along with the basal laminar area of smooth muscle, and its expression pattern was disrupted 7 days after arterial injury. LRRFIP1 mRNA was decreased 14 days after injury. Delivery of miR-132 to rat carotid artery reduced LRRFIP1 expression and attenuated neointimal proliferation in carotid artery injury models.

CONCLUSIONS

Our results suggest that miR-132 is a novel regulator of VSMC proliferation that represses neointimal formation by inhibiting LRRFIP1 expression.

Enhancer of polycomb1 lessens neointima formation by potentiation of myocardin-induced smooth muscle differentiation

OBJECTIVE

Previously, we reported that enhancer of polycomb1 (Epc1) induces skeletal muscle differentiation through the serum response factor (SRF). Considering that SRF plays a critical role in vascular smooth muscle cell (VSMC) differentiation, we expected that Epc1 also works in VSMCs. Here we examined the effect of Epc1 on neointima formation after arterial balloon injury and the underlying mechanism.

METHODS

Epc1 expression was examined in carotid artery injury or VSMC models. Interaction with myocardin (Myocd), a master regulator of smooth muscle differentiation, was examined by immunoprecipitation or promoter analysis with smooth muscle (SM) 22α promoter. Finally, we investigated whether local delivery of Epc1 regulated neointimal formation after injury.

RESULTS

Epc1 expression was down-regulated during proliferation induced by platelet-derived growth factor BB, whereas it was upregulated during differentiation in VSMCs. Forced expression of Epc1 induced VSMC differentiation. Epc1 physically interacted with Myocd to synergistically activate SM22α promoter activity. Transient transfection of Epc1 enhanced the physical interaction between Myocd and SRF, whereas that interaction was reduced when A10 cells were treated with siRNA for Epc1. Local delivery of Epc1 significantly reduced neointima formation induced by balloon injury.

CONCLUSIONS

Our results indicate that Epc1 induces VSMC differentiation by interacting with Myocd to induce SRF-dependent smooth muscle genes. We propose that Epc1 acts as a novel negative regulator of neointima formation after carotid injury.

Abstract P187: Casein Kinase 2/Histone Deacetylase 2/Krúppel-like Factor 4 Is a Novel Axis of Development of Cardiac Hypertrophy

Background. Cardiac hypertrophy is characterized by transcriptional reprogramming of fetal gene expression, and histone modifiers are tightly linked to the regulation of those genes. We previously reported that activation of histone deacetylase (HDAC) 2, one of the class I HDACs, mediates hypertrophy. Here we suggest that disinhibiting of kruppel-like factor 4 (Klf4) by casein kinase-2α1 (CK2α1)-dependent phosphorylation of HDAC2 S394 develop the cardiac hypertrophy.

Methods and Results. Hypertrophic stimuli phosphorylated Hdac2 S394, which was necessary for its enzymatic activation and thereby for the development of hypertrophic phenotypes. Transgenic mice overexpressing Hdac2-wild type exhibited cardiac hypertrophy, whereas those expressing phosphorylation-resistant Hdac2 S394A did not. Compared with that in age-matched normal human hearts, phosphorylation of Hdac2 S394 was dramatically increased in hypertrophic cardiomyopathy patients. Hypertrophy-induced phosphorylation of Hdac2 S394 and its enzymatic activity were completely blocked either by CK2-blockers or by CK2a1 siRNA. Hypertrophic stimuli led CK2α1 to be activated, and its chemical inhibitors blocked hypertrophy in both phenylephrine-treated cardiomyocytes and in isoproterenol-administered mice. However, by utilizing KLF4-binding element-disrupted Nppa promoter, treatment with either TBB or TBCA failed to reduce the mutant promoter activity. These results emphasized that CK2α1-induced hypertrophic events are dependent on both Hdac2 and KLF4. CK2α1-transgenic mice developed hypertrophy, which was attenuated by administration of trichostatin A, an HDAC inhibitor. Overexpression of CK2α1 caused hypertrophy in cardiomyocytes, whereas its chemical inhibitors as well as Hdac2 S394A blunted it. Hypertrophy in CK2α1-transgenic mice was exaggerated by crossing these mice with Hdac2-transgenic mice. By contrast, however, it was blocked when CK2α1-transgenic mice were crossed with Hdac2 S394A-transgenic mice.

Conclusions. We have demonstrated a novel mechanism in the development of cardiac hypertrophy by which CK2 activates HDAC2 via phosphorylating HDAC2 S394 and consequence down-regulation of KLF4.

Abstract P226: Small Heterodimer Partner Negatively Regulates Cardiac Hypertrophy Through Upregulation of GATA6

Small heterodimer partner (SHP; NR0B2) is an atypical orphan nuclear receptor that regulates a variety of cellular events such as cell proliferation, differentiation and metabolism in liver and bone. However, the role of SHP in heart has not yet been elucidated. In this study, we investigated the functional roles of SHP in cardiac hypertrophy. In rat neonatal cardiomyocytes model, phenylephrine (PE) down-regulated expression of SHP. Transient transfection of SHP decreased the promoter activity of Nppa (natriuretic polypeptide precursor type A). Adenovirus-mediated overexpression of SHP (Ad-SHP) blocked gene expressions of GATA4, GATA6, and serum response factor (SRF). The increase in [ 3 H]-leucine incorporation induced by PE or fetal bovine serum (FBS) was dramatically reduced by Ad-SHP. Likewise, increases in cell size with those hypertrophic stresses were significantly attenuated by Ad-SHP. The expressions of atrial natriuretic factor (ANF), β-myosin heavy chain (βMHC), and skeletal α-actin were significantly higher in hearts of SHP null mice. SHP physically interacted with GATA6 in mammalian cells. SHP significantly decreased the activation of -3003 Nppa promoter induced by GATA6. The action of SHP on Nppa promoter activity was partially recovered by GATA6. Taken together, these results suggest that SHP works as a novel anti-hypertrophic regulator by repressing GATA6.

Histone methyltransferase SETD3 regulates muscle differentiation

Histone lysine methylation, as one of the most important factors in transcriptional regulation, is associated with a various physiological conditions. Using a bioinformatics search, we identified and subsequently cloned mouse SET domain containing 3 (SETD3) with SET (Su(var)3-9, Enhancer-of-zeste and Trithorax) and Rubis-subs-bind domains. SETD3 is a novel histone H3K4 and H3K36 methyltransferase with transcriptional activation activity. SETD3 is expressed abundantly in muscular tissues and, when overexpressed, activates transcription of muscle-related genes, myogenin, muscle creatine kinase (MCK), and myogenic factor 6 (Myf6), thereby inducing muscle cell differentiation. Conversely, knockdown of SETD3 by shRNA significantly retards muscle cell differentiation. In this study, SETD3 was recruited to the myogenin gene promoter along with MyoD where it activated transcription. Together, these data indicate that SETD3 is a H3K4/K36 methyltransferase and plays an important role in the transcriptional regulation of muscle cell differentiation.

Ret finger protein inhibits muscle differentiation by modulating serum response factor and enhancer of polycomb1

Skeletal myogenesis is precisely regulated by multiple transcription factors. Previously, we demonstrated that enhancer of polycomb 1 (Epc1) induces skeletal muscle differentiation by potentiating serum response factor (SRF)-dependent muscle gene activation. Here, we report that an interacting partner of Epc1, ret finger protein (RFP), blocks skeletal muscle differentiation. Our findings show that RFP was highly expressed in skeletal muscles and was downregulated during myoblast differentiation. Forced expression of RFP delayed myoblast differentiation, whereas knockdown enhanced it. Epc1-induced enhancements of SRF-dependent multinucleation, transactivation of the skeletal α-actin promoter, binding of SRF to the serum response element, and muscle-specific gene induction were blocked by RFP. RFP interfered with the physical interaction between Epc1 and SRF. Muscles from rfp knockout mice (Rfp(-/-)) mice were bigger than those from wild-type mice, and the expression of SRF-dependent muscle-specific genes was upregulated. Myotube formation and myoblast differentiation were enhanced in Rfp(-/-) mice. Taken together, our findings highlight RFP as a novel regulator of muscle differentiation that acts by modulating the expression of SRF-dependent skeletal muscle-specific genes.

Roles and targets of class I and IIa histone deacetylases in cardiac hypertrophy

Cardiac hypertrophy occurs in association with heart diseases and ultimately results in cardiac dysfunction and heart failure. Histone deacetylases (HDACs) are post-translational modifying enzymes that can deacetylate histones and non-histone proteins. Research with HDAC inhibitors has provided evidence that the class I HDACs are pro-hypertrophic. Among the class I HDACs, HDAC2 is activated by hypertrophic stresses in association with the induction of heat shock protein 70. Activated HDAC2 triggers hypertrophy by inhibiting the signal cascades of either Krüppel like factor 4 (KLF4) or inositol polyphosphate-5-phosphatase f (Inpp5f). Thus, modulators of HDAC2 enzymes, such as selective HDAC inhibitors, are considered to be an important target for heart diseases, especially for preventing cardiac hypertrophy. In contrast, class IIa HDACs have been shown to repress cardiac hypertrophy by inhibiting cardiac-specific transcription factors such as myocyte enhancer factor 2 (MEF2), GATA4, and NFAT in the heart. Studies of class IIa HDACs have shown that the underlying mechanism is regulated by nucleo-cytoplasm shuttling in response to a variety of stress signals. In this review, we focus on the class I and IIa HDACs that play critical roles in mediating cardiac hypertrophy and discuss the non-histone targets of HDACs in heart disease.

Hopx and Hdac2 interact to modulate Gata4 acetylation and embryonic cardiac myocyte proliferation

Regulation of chromatin structure via histone modification has recently received intense attention. Here, we demonstrate that the chromatin-modifying enzyme histone deacetylase 2 (Hdac2) functions with a small homeodomain factor, Hopx, to mediate deacetylation of Gata4, which is expressed by cardiac progenitor cells and plays critical roles in the regulation of cardiogenesis. In the absence of Hopx and Hdac2 in mouse embryos, Gata4 hyperacetylation is associated with a marked increase in cardiac myocyte proliferation, upregulation of Gata4 target genes, and perinatal lethality. Hdac2 physically interacts with Gata4, and this interaction is stabilized by Hopx. The ability of Gata4 to transactivate cell cycle genes is impaired by Hopx/Hdac2-mediated deacetylation, and this effect is abrogated by loss of Hdac2-Gata4 interaction. These results suggest that Gata4 is a nonhistone target of Hdac2-mediated deacetylation and that Hdac2, Hopx, and Gata4 coordinately regulate cardiac myocyte proliferation during embryonic development.

Enhancer of polycomb1 acts on serum response factor to regulate skeletal muscle differentiation

Skeletal muscle differentiation is well regulated by a series of transcription factors. We reported previously that enhancer of polycomb1 (Epc1), a chromatin protein, can modulate skeletal muscle differentiation, although the mechanisms of this action have yet to be defined. Here we report that Epc1 recruits both serum response factor (SRF) and p300 to induce skeletal muscle differentiation. Epc1 interacted physically with SRF. Transfection of Epc1 to myoblast cells potentiated the SRF-induced expression of skeletal muscle-specific genes as well as multinucleation. Proximal CArG box in the skeletal alpha-actin promoter was responsible for the synergistic activation of the promoter-luciferase. Epc1 knockdown caused a decrease in the acetylation of histones associated with serum response element (SRE) of the skeletal alpha-actin promoter. The Epc1.SRF complex bound to the SRE, and the knockdown of Epc1 resulted in a decrease in SRF binding to the skeletal alpha-actin promoter. Epc1 recruited histone acetyltransferase activity, which was potentiated by cotransfection with p300 but abolished by si-p300. Epc1 directly bound to p300 in myoblast cells. Epc1+/- mice showed distortion of skeletal alpha-actin, and the isolated myoblasts from the mice had impaired muscle differentiation. These results suggest that Epc1 is required for skeletal muscle differentiation by recruiting both SRF and p300 to the SRE of muscle-specific gene promoters.

Activation of Histone Deacetylase 2 by Inducible Heat Shock Protein 70 in Cardiac Hypertrophy

Diverse cardiac diseases induce cardiac hypertrophy, which leads to dilatation and heart failure. We previously reported that hypertrophy can be blocked by class I histone deacetylase (HDAC) inhibitor, which prompted us to investigate the regulatory mechanism of class I HDACs. Cardiac hypertrophy was introduced by aortic banding, by infusion of isoproterenol or angiotensin II, or by swimming. Hypertrophic stimuli transiently elevated the activity of histone deacetylase-2 (Hdac2), a class I HDAC. In cardiomyocytes, forced expression of Hdac2 simulated hypertrophy in an Akt-dependent manner, whereas enzymatically inert Hdac2 H141A failed to do so. Hypertrophic stimuli induced the expression of heat shock protein (Hsp)70. The induced Hsp70 physically associated with and activated Hdac2. Hsp70 overexpression produced a hypertrophic phenotype, which was blocked either by siHdac2 or by a dominant negative Hsp70ΔABD. In Hsp70.1 −/− mice, cardiac hypertrophy and Hdac2 activation were significantly blunted. Heat shock either to cardiomyocytes or to mice activated Hdac2 and induced hypertrophy. However, heat shock-induced Hdac2 activation was blunted in the cardiomyocytes isolated from Hsp70.1 −/− mice. These results suggest that the induction of Hsp70 in response to diverse hypertrophic stresses and the ensuing activation of HDAC2 trigger cardiac hypertrophy, emphasizing HSP70/HDAC2 as a novel mechanism regulating hypertrophy.

Hyperventilation-induced nystagmus in peripheral vestibulopathy and cerebellopontine angle tumor

OBJECTIVE

To determine the incidence and characteristics of hyperventilation-induced nystagmus (HIN) in cerebellopontine angle (CPA) tumors and unilateral peripheral vestibulopathy (UPV), and to elucidate differential contribution of hyperventilation to bring out vestibular asymmetry between acute and chronic phases of UPV.

METHODS

We recorded horizontal HIN in 33 patients with CPA tumors and 145 with UPV. The UPV included patients of either acute (7 days or less from symptom onset, n = 47) or chronic (more than 7 days from symptom onset, n = 98) phases.

RESULTS

The incidence of HIN was higher in the CPA tumor than in the UPV group (82 vs 34%, p < 0.01) and was also higher in the acute than in the chronic UPV group (60 vs 21%, p < 0.01). Furthermore, HIN was more commonly ipsilesional (i-HIN) in the CPA tumor than in the UPV group (52 vs 8%, p < 0.01) and more commonly ipsilesional in the acute than in the chronic UPV group (21 vs 1%, p < 0.01). The patients with i-HIN and acoustic neuroma had a tendency to harbor smaller tumors and to have less severe caloric asymmetry.

CONCLUSIONS

The contribution of hyperventilation on vestibular nystagmus differs depending on the disease phase or underlying pathologies. Our study demonstrates that hyperventilation-induced nystagmus (HIN) beating to the side of reduced caloric response, hearing impairment, or abnormal auditory brainstem response responses may be a valuable sign for bedside detection of cerebellopontine angle (CPA) tumors. CPA tumor should be a prime suspicion in patients with acute vertigo and ipsilesional HIN, especially when the vertigo accompanies hearing impairments.