Improvement Of Left Ventricular Dysfunction Research Articles

Protective role of CXCR7 activation in neonatal hyperoxia-induced systemic vascular remodeling and cardiovascular dysfunction in juvenile rats

Neonatal hyperoxia induces long-term systemic vascular stiffness and cardiovascular remodeling, but the mechanisms are unclear. Chemokine receptor 7 (CXCR7) represents a key regulator of vascular homeostasis and repair by modulating TGF-β1 signaling. This study investigated whether pharmacological CXCR7 agonism prevents neonatal hyperoxia-induced systemic vascular stiffness and cardiac dysfunction in juvenile rats. Newborn Sprague Dawley rat pups assigned to room air or hyperoxia (85% oxygen), received CXCR7 agonist, TC14012 or placebo for 3 weeks. These rat pups were maintained in room air until 6 weeks when aortic pulse wave velocity doppler, cardiac echocardiography, aortic and left ventricular (LV) fibrosis were assessed. Neonatal hyperoxia induced systemic vascular stiffness and cardiac dysfunction in 6-week-old rats. This was associated with decreased aortic and LV CXCR7 expression. Early treatment with TC14012, partially protected against neonatal hyperoxia-induced systemic vascular stiffness and improved LV dysfunction and fibrosis in juvenile rats by decreasing TGF-β1 expression. In vitro, hyperoxia-exposed human umbilical arterial endothelial cells and coronary artery endothelial cells had increased TGF-β1 levels. However, treatment with TC14012 significantly reduced the TGF-β1 levels. These results suggest that dysregulation of endothelial CXCR7 signaling may contribute to neonatal hyperoxia-induced systemic vascular stiffness and cardiac dysfunction.

Cardiac hypertrophy and fibrosis were attenuated by olive leaf extract treatment in a rat model of diabetes.

The key role of fibrosis and hypertrophy processes in developing diabetes-induced heart injury has been demonstrated. Considering the known hypoglycemic effects of olive leaf extract (OLE), we decided to investigate its potential effect and associated mechanisms on cardiac fibrosis and myocardial hypertrophy in streptozotocin (STZ)-induced diabetic rats. Eight groups were included in this study: control, diabetic, diabetic-OLEs (100, 200 and 400 mg/kg), diabetic-metformin (300 mg/kg), diabetic-valsartan (30 mg/kg), and diabetic-metformin/valsartan (300/30 mg/kg). After a treatment period of 6 weeks, echocardiography was used to assess cardiac function. Heart-to-body weight ratio (HW/BW) and fasting blood sugar (FBS) were measured. Myocardial histology was examined by Masson's trichrome staining. Gene expressions of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), β-myosin heavy chain (β-MHC), TGF-β1, TGF-β3, angiotensin II type 1 receptor (AT1), alpha-smooth muscle actin (α-SMA), and collagen were evaluated by the quantitative real-time PCR in heart tissue. A reduction in the FBS level and HW/BW ratio in the extract groups was obvious. The improvement of left ventricular dysfunction, cardiac myocytes hypertrophy, and myocardial interstitial fibrosis was also observed in treated groups. A lowering trend in the expression of all hypertrophic and fibrotic indicator genes was evident in the myocardium of OLE treated rats. Our data indicated that OLE could attenuate fibrosis and reduce myocardial hypertrophy markers, thus improving the cardiac function and structure in the STZ-induced diabetic rats. PRACTICAL APPLICATIONS: This study demonstrates that olive leaf extract in addition to lowering blood glucose levels and the heart-to-body weight ratio (HW/BW) may also improve cardiac function and reduce cardiac hypertrophy and fibrosis in cardiac tissue, which leads to inhibition of diabetic heart damage. Thus it is possible that including olive leaf extracts in the diets of individuals with diabetes may assist in lowering cardiovascular disease risk factors.

Abstract 14035: IL-4Ra-Mediated CD206 + Macrophage Activation Promotes Adverse Remodeling in the Failing Heart

Background: In heart failure (HF), cardiac macrophages are largely comprised of CD206 + cells that locally self-renew independent of the blood monocyte pool. We tested the hypothesis that cardiac CD206 + macrophages expressing interleukin (IL)-4Rα are key mediators of adverse left ventricular (LV) remodeling in HF. Methods and Results: Adult male C57BL/6 mice underwent non-reperfused myocardial infarction (MI) to induce HF. HF mice (vs. sham mice) exhibited progressive expansion of cardiac CD206 + macrophages up to 8 w post-MI (accounting for ~80% total macrophages), whereas cardiac CD206 - macrophages peaked at 48 h and then decreased by 90% at 1 w post-MI and beyond. Cardiac CD206 + macrophage levels negatively correlated with LV ejection fraction, and positively correlated with remote zone fibrosis. These cells were predominantly CCR2 - and nearly half expressed IL-4Rα, whereas CD206 - macrophages, monocytes, neutrophils, and T-cells had markedly lower IL-4Rα expression. Bone marrow-derived macrophages (BMDMs) polarized with IL-4 (M[IL-4]) induced myofibroblast activation in vitro . Intramyocardial adoptive transfer of M[IL-4] macrophages (1 x 10 6 cells) into naïve mice induced progressive LV chamber dilation and dysfunction, and augmented cardiac fibrosis over 4 w. Next, sham and HF mice with similar LV remodeling at 4 w post-MI were given IL-4Rα-specific or control antisense oligonucleotides (ASOs) 40 mg/kg i.p. every 3 d for 4 w. HF mice receiving IL-4Rα ASOs exhibited profoundly diminished cardiac CD206 + IL-4Rα + (and total CD206 + ) macrophage levels, substantially less macrophage proliferation and phagocytosis, and improvement of LV dysfunction, hypertrophy, and fibrosis. Moreover, both M[IL-4] CD206 + BMDMs and CD206 + IL-4Rα + macrophages in failing hearts expressed high levels of Fizz1 (found in inflammatory zone 1). Blocking FIZZ1 expression and/or secretion blunted the profibrotic capacity of M[IL-4] CD206 + BMDMs in vitro . Conclusion: CD206 + IL-4Rα + macrophages proliferate and expand in the failing heart and are key drivers of pathological remodeling and fibrosis, in part through the secretion of FIZZ1. Inhibition of CD206 + macrophage IL-4Rα signaling may be a fruitful therapeutic approach for alleviating LV remodeling in HF.

P3479Sequential stimulation and inhibition of lysophosphatidic acid receptor 4 are critical for cardiac differentiation and repair

Abstract Background The clinical application of cell therapy to repair the damaged heart needs to understand the precise differentiation process of stem cells and the characteristics of cardiac progenitor cells. Purpose We examined the cardiac-specific markers that expressed on the cell surface and determined their functional significance during cardiac differentiation. Methods and results We screened cell-surface expressing proteins on cardiac progenitor cells at differentiation day 3 compared to undifferentiated pluripotent stem cells (PSCs). Among candidates, we identified lysophosphatidic acid receptor 4 (LPAR4) that is a G protein-coupled receptor. During in vitro differentiation of mouse PSCs toward cardiac cells, LPAR4 expression peaked for 3–5 days and then and declined immediately. Also in vivo, LPAR4 was specifically expressed in the early stage of heart development in embryos and disappeared completely in adults, suggesting that stimulatory signal of LPAR4 at an early stage should be shut off for further progression of differentiation. We next have identified the LPAR4 downstream signaling molecule, p38MAPK, by comparing PSCs and LPAR4 knockdown PSCs. In both mouse and human PSCs, ODP (LPAR4 specific agonist) followed by p38MAPK blocker (SB203580) treatment significantly increased cardiac differentiation efficiency. Furthermore, we investigated whether LPAR4 is the maker for adult cardiac progenitor cells. We found that LPAR4-positive cells were rarely present in normal adult mouse hearts, but LPAR4-positive cells were increased when the heart was damaged. LPAR4-positive cells from adult hearts differentiated into cardiomyocytes. After myocardial infarction (MI), the sequential stimulation and inhibition of LPAR4 with ODP and p38MAPK blocker resulted in the reduction of infarct size and improvement of left ventricular dysfunction. Conclusion We demonstrated that LPAR4 is a cardiac progenitor-specific marker and its functional significance during cardiac differentiation and regeneration. Our findings provide a new insight in cell-free cardiac repair by the modulation of progenitor-specific downstream signaling. Acknowledgement/Funding Grants from “Strategic Center of Cell and Bio Therapy” (grant number: HI17C2085) and “Korea Research-Driven Hospital” (HI14C1277)

Effect of ranolazine on improvement of left ventricular dysfunction in patients with chronic stable angina: A randomized controlled clinical trial

Objectives: To study the effect of ranolazine on improvement of left ventricular (LV) dysfunction in comparison to trimetazidine in patients with chronic stable angina (CSA). Ranolazine is an anti-anginal agent that acts on the late inward sodium current and prevents pathologic intracellular calcium accumulation that leads to ischemia, myocardial dysfunction, and electrical instability. Methodology: After screening and obtaining informed consent, 29 patients with CSA who have sustained ST-Elevation Myocardial Infarction more than 12 weeks ago with LV ejection fraction (LVEF) ≤40% in a 2:1 ratio to receive ranolazine 500 mg BD (n = 19) or trimetazidine 35 mg BD (n = 10) were enrolled in the study. The patients were evaluated at the end of 8 weeks for the improvement in LV dysfunction by transthoracic echocardiography. Results: No significant difference was found in the baseline characteristics of the patients between the two groups except the increased body mass index among users of trimetazidine (26.3 ± 5.07 vs. 22.1 ± 3.26, P = 0.03). Study patients receiving ranolazine 500 mg BD for 8 weeks significantly improved the LVEF. No improvement was seen in diastolic function. Ranolazine was well tolerated among the patients. Conclusion: Ranolazine at a dose of 500 mg BD given for 8 weeks helps in improving the LVEF in patients with CSA and is a suitable option than trimetazidine among patients with CSA.

Angiotensin II receptor blockers suppress the release of stromal cell-derived factor-1α from infarcted myocardium in patients with acute myocardial infarction

BackgroundAlthough angiotensin II receptor blockers (ARBs) have been shown to have anti-inflammatory effects on infarcted myocardium in experimental models, little is known in humans. Stromal cell-derived factor-1α (SDF-1α), a pro-inflammatory chemokine, is released from infarcted tissue in patients with acute myocardial infarction (AMI). This study examined whether ARBs suppress SDF-1α production in the infarcted lesion in patients with AMI. MethodsSDF-1α levels were measured by enzyme-linked immunosorbent assays in plasma obtained from the aortic root (AO) and the anterior interventricular vein (AIV) in 50 patients with an anterior AMI. Measurement of SDF-1α levels and left ventriculography were repeated at discharge and 6 months after AMI. Patients were divided into 2 groups according to treatment with ARBs, which were administered at the discretion of the attending physician after admission. ResultsThe AIV–AO gradient of SDF-1α, reflecting SDF-1α release from the infarcted myocardial region, decreased between the time of discharge and 6 months after AMI in patients taking an ARB. In contrast, the SDF-1α transcardiac gradient did not change in patients not taking an ARB. Among the clinical parameters tested, only the use of ARBs was significantly associated with percent changes in the SDF-1α transcardiac gradient from the time of discharge to 6 months after AMI in a linear regression analysis (r=−0.31, p=0.03). The SDF-1α transcardiac gradient 6 months after AMI was inversely correlated with the percent change in left ventricular (LV) ejection fraction (r=−0.52, p<0.01) and positively correlated with the percent change in LV end-diastolic volume index (r=0.57, p<0.01) and LV end-systolic volume index (r=0.54, p<0.01) during 6 months after AMI. ConclusionsARB treatment suppressed SDF-1α release from the infarcted myocardial region, which was associated with improvement in LV dysfunction and adverse remodeling in AMI survivors.

Enhanced-autophagy by exenatide mitigates doxorubicin-induced cardiotoxicity

ObjectivesExenatide is a glucagon-like peptide-1 analogue that mitigates myocardial injury caused by ischemia-reperfusion injury via the survival signaling pathway. We hypothesized that exenatide would provide a protective effect in doxorubicin-induced cardiotoxicity. MethodsH9c2 cardiomyocytes were pre-treated with exenatide followed by doxorubicin (DOX), and cell viability and intracellular reactive oxygen species (ROS) were subsequently measured. In order to determine the role of autophagy, we performed western blot as well as TUNEL and autophagosome staining. Additionally, rats were treated with exenatide 1h prior to every DOX treatment. Left ventricular (LV) function and performance were then assessed by echocardiography. Myocardial and serum ROS was measured with DHE fluorescence and ROS/RNS assay. ResultsDOX-induced caspase-3 activation decreased after pre-treatment with exenatide both in vivo and in vitro. Oxidative stress was attenuated by exenatide in H9c2 cells, as well as in cardiac tissue and serum. The number of autophagosomes and autophagic markers were further increased by exenatide in the DOX-treated H9c2 cells, which mediated AMPK activation. Suppression of the autophagosome abolished exenatide-induced anti-apoptotic effect. Echocardiography showed that pre-treatment with exenatide significantly improved LV dysfunction that is induced by DOX treatment. Exenatide inhibits the DOX-induced production of intracellular ROS and apoptosis in the myocardium. The autophagic markers increased in exenatide pre-treated cardiac tissue. ConclusionExenatide reduces DOX-induced apoptosis of cardiomyocytes by upregulating autophagy and improving cardiac dysfunction. These novel results highlight the therapeutic potential of exenatide to prevent doxorubicin cardiotoxicity.

0542 : Vascular smooth muscle mineralocorticoid receptor contributes to coronary and left ventricular dysfunction after myocardial infarction

Mineralocorticoid receptor (MR) antagonists slow down the progression of heart failure after myocardial infarction (MI), but the cell-specific role of MR in these benefits is unclear. In the present study, the role of MR expressed in vascular smooth muscle cells (VSMC) was investigated. Two months after coronary artery ligation causing MI, mice with VSMC-specific MR deletion (MI-MRSMKO) and mice treated with the MR antagonist finerenone (MIfine) had improved left ventricular (LV) compliance and elastance when compared to infarcted control mice (MI-CTL), as well as reduced interstitial fibrosis. Importantly, the coronary reserve assessed by magnetic resonance imaging was preserved (difference in myocardial perfusion before and after induction of vasodilatation, ml/mg/min: MI-CTL: 1.1±0.5, NS; MIMRSMKO: 4.6±1.6, P<0.05; MI-fine: 3.6±0.7, P<0.01). The endothelial function, tested on isolated septal coronary arteries by analyzing the acetylcholineinduced NO-dependent relaxation, was also improved by MR deletion in VSMC or by finerenone treatment (relaxation %: MI-CTL: 36±5, MIMRSMKO: 54±3 and MI-fine: 76±4; P<0.05). Such impairment of the coronary endothelial function upon MI involved an oxidative-stress that was reduced when MR was deleted in VSMC or by finerenone treatment. Moreover, short-term incubation of coronary arteries isolated from non-infarcted animals with low dose angiotensin-II (10-9mol/L) induced oxidative-stress and impaired acetylcholine-induced relaxation in CTL but neither in MRSMKO nor in mice pre-treated with finerenone. In conclusion, deletion of MR in VSMC improved LV dysfunction after MI, likely through maintenance of the coronary reserve and improvement of coronary endothelial function. MR blockage by finerenone had similar effects. The author hereby declares no conflict of interest

Omega-3-fatty acid adds to the protective effect of flax lignan concentrate in pressure overload-induced myocardial hypertrophy in rats via modulation of oxidative stress and apoptosis

Objective of the present investigation was to study the effect of the flax lignan concentrate (FLC) and Omega-3-fatty acid (O-3-FA) on myocardial apoptosis, left ventricular (LV) contractile dysfunction and electrocardiographic abnormalities in pressure overload-induced cardiac hypertrophy. The rats were divided into five groups such as sham, aortic stenosis (AS), AS+FLC, AS+O-3-FA and AS+FLC+O-3-FA. Cardiac hypertrophy was produced in rats by abdominal aortic constriction. The rats were treated with FLC (400mg/kg, p.o.), O-3-FA (400mg/kg, p.o.) and FLC+O-3-FA orally per day for four weeks. The LV function, myocardial apoptosis, and oxidative stress were quantified. FLC+O-3-FA treatment significantly reduced hemodynamic changes, improved LV contractile dysfunction, reduced cardiomyocyte apoptosis and cellular oxidative stress. Moreover, it significantly up-regulated the VEGF expression and decreased TNF-alpha level in serum. The histological analysis also revealed that FLC+O-3-FA treatment markedly preserved the cardiac structure and inhibited interstitial fibrosis. In conclusion, FLC+O-3-FA treatment improved LV dysfunction, inhibited cardiomyocyte apoptosis, improved myocardial angiogenesis, conserved activities of membrane-bound phosphatase enzymes and suppressed inflammation through reduced oxidative stress in an additive manner than FLC alone and O-3-FA alone treatment in pressure overload-induced cardiac hypertrophy.

Abstract 16663: Patient and Cell Characteristics Associated With Clinical Outcomes in the CCTRN LateTIME Trial

Background and Hypothesis: In the CCTRN LateTIME trial, there was no improvement versus placebo in cardiac function 6 months after intracoronary infusion of autologous bone marrow mononuclear cells (BMC), 2-3 weeks post-MI. We hypothesized that clinical outcomes are associated with patient demographics and BMC populations that contribute to the efficacy of the intervention. Methods: Left ventricular (LV) function was evaluated at baseline and at 6 months. BMC study product data associated with phenotype and colony formation capability were collected at baseline. Principal components analysis was used to define a composite variable, LV dysfunction, encompassing both LV volume and wall motion data. Case control analysis was then conducted comparing those with improved LV dysfunction (cases) with those without (controls). Results: Hypertension, diabetes, and obesity were associated with lower levels of endothelial progenitor cells; whereas hyperlipidemia was inversely associated with CD11b+ cells, and obesity with CD3+ cells. Adjusted multivariate analysis indicated that CD11b+ cells were negatively associated with LV function; both globally (P&lt;0.02) and regionally (P&lt;0.01 and P&lt;0.001, border and infarct zone wall motion, respectively). Global LV function was positively associated with MSC colonies formed (P&lt;0.02) and regional LV function (border zone wall motion) and with cell viability (P&lt;0.03). Case control analysis revealed a significant association of CD133+, CD34+/CD31+, and CXCR4dim cells with cases. Increased LV dysfunction was associated with CD11b+cells. Conclusions: These results suggest that CVD risk factors significantly affect BMC and that baseline BMC characteristics of individual patients may be important determinants of clinical improvement. Higher frequencies or better function of specific cell populations with endothelial, mesenchymal and migratory phenotype may predispose patients to clinical improvements, whereas higher level of CD11b+ in the BM may contribute to impaired LV function. Product selection or treatment to modify bone marrow constituents, such as negative selection of CD11b+ cells prior to BMC injection, may be a potential strategy to improve outcomes of future clinical trials.

Abstract 180: Synergistic Salutary Effects of HMG-CoA Reductase Inhibitor and Angiotensin II Receptor Blocker on Load-induced Heart Failure

We have shown previously that combined HMG-CoA reductase inhibitor (statin) and angiotensin II receptor blocker (ARB) therapy significantly improves both symptoms and left ventricular (LV) function over time in patients with heart failure (HF) by a clinical study [ HF-COSTAR Trial]. We elucidated the mechanisms of combination therapy with the ARB (losartan, LOS) and long-acting and statin (simvastatin, SIM) for the treatment of load-induced heart failure. Salt-loaded Dahl salt-sensitive (DS) rats were treated with vehicle, LOS (5mg/kg/day), SIM (2mg/kg/day) and LOS + SIM for 16 weeks. LOS and SIM in combination improved LV dysfunction (ΔLV fractional shortening; LOS = 60%, SIM = 42%, LOS + SIM = 24%, p &lt;0.05), limited LV hypertrophy (ΔLV septal thickness; LOS = −21%, SIM = −18%, LOS + SIM = −13%, p &lt;0.05) and reduced cardiac fibrosis (ΔLV collagen density; LOS = −26%, SIM = −16%, LOS + SIM = −28%, p &lt;0.05) more than LOS or SIM alone. Both Rho and matrix metalloprotease-9 (MMP-9) activity in LV tissue were increased in untreated DS rats, and LOS and SIM in combination decreased these changes more than did LOS and SIM monotherapies. We confirmed that the plasma level of Exp-3174 (E3174), a LOS metabolite and a potent inverse agonist of angiotensin II receptor type 1, was higher in rats treated with LOS and SIM in combination than in those treated with LOS alone (E3174/LOS ratio; LOS = 2.6 ± 0.3 vs. LOS + SIM = 3.2 ± 0.2, p &lt;0.05). Next, to mimic the response of volume-overload heart failure in vitro , cultured neonatal rat cardiomyocytes (CMs) were cyclically stretched. Stretch-induced increased CM hypertrophy was suppressed by pretreatment with both SIM and E3174 more than by pretreatment with LOS, E3174, SIM, or LOS and SIM in combination. Mechanical stretch also induced activation of extracellular signal regulated kinase (ERK) and the stretch-induced ERK activation of CMs was also significantly suppressed by SIM + E3174. In conclusion, LOS and SIM had beneficial myocardial effects in rats with salt-sensitive hypertension, partly through promoting the accumulation of plasma E3174. SIM enhanced the myocardial protective effects of LOS through suppression of Rho and MMP-9 activity. Thus, a combination of ARB with statin has a promising potential as a therapeutic strategy for HF.

Use of Intravenous Immunoglobulin Compared With Standard Therapy is Associated With Improved Clinical Outcomes in Children With Acute Encephalitis Syndrome Complicated by Myocarditis

Although an autoimmune mechanism has been postulated for acute encephalitis syndrome (AES) complicated by myocarditis, immunomodulatory treatment strategies are still under investigation. To study the role of intravenous immunoglobulin (IVIG) in AES complicated by myocarditis in children age 2-12 years. This nonrandomized study was conducted in a tertiary care teaching hospital from July 2008 to January 2010. A total of 83 consecutive children with AES complicated by myocarditis were enrolled. Diagnosis of myocarditis was based on clinical, electrocardiogram, and echocardiogram findings. Patients were allocated to the two groups based on the days of the week: Those presenting on Monday and Friday were allocated to IVIG treatment (group I), and those presenting on the other days of the week to standard care (group II). Group I (n = 26) patients received IVIG at a dose of 400 mg/kg/day for 5 days in addition to standard care. All baseline and outcome data were recorded prospectively in a prestructured performa. The primary outcomes were mortality and improvement of left-ventricular dysfunction. A total of 83 children were studied: 26 in group I and 57 in group II. The mean (SD) age of the enrolled children was 4.6 years (3.1). The baseline characteristics were comparable between the two groups. A viral etiology could be established in 14 children, with the 2 most common agents isolated being Coxackie virus and enterovirus. Mortality was lower in the IVIG group [n = 1 (3.8 %)] patients compared with the standard care group [n = 13 (22.8 %)] with a relative risk of 0.17 (95 % CI = 0.02, 1.22). The difference in mortality reached borderline significance (p = 0.05). At discharge, mean (SD) ejection fraction improved from 32.8 % (6.31 %) to 49.5 % (9.04 %) in group I patients, which was significantly greater than that of group II (p = 0.001). Use of IVIG seemed to have a beneficial effect in terms of improved clinical outcomes in children with AES complicated by myocarditis. Our findings need further validation before IVIG can be incorporated into the treatment protocol of these children.

Abstract P136: E2F2/4 Regulated by Serine 21 Phosphorylation of GSK-3α Play Compensatory Roles During Pressure Overload

Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase with two isoforms, alpha and beta, which have distinct functions in cardiomyocytes (CMs). GSK-3alpha is phosphorylated at S21 during pressure overload (PO), and inhibition of S21 phosphorylation in GSK-3alpha S21A knock-in (alpha−KI) mice promotes hypertrophy and heart failure in response to PO, accompanied by decreases in the total number of CMs in the heart. Since GSK-3alpha downregulates cyclinD1 in the nucleus, GSK-3alpha may negatively regulate E2F-mediated transcription. Reporter gene assays showed that the transcriptional activity of E2F was increased by GSK-3alpha knockdown (1.75 fold, p&lt;0.05). To evaluate the role of E2F isoforms in regulating cardiac hypertrophy and function during PO, E2F1−/−, E2F2−/+, E2F4−/+, and wild type (WT) mice were subjected to transverse aortic constriction (TAC). Left ventricular (LV) weight/ tibial length (LVW/TL) was significantly greater and LV ejection fraction (LVEF) was significantly decreased in both E2F2−/+ and E2F4−/+ after 2 weeks of TAC (LVW/TL: E2F2−/+=7.1±0.3, E2F4−/+=7.0±0.4, WT=5.9±0.3, p&lt;0.05 vs. WT; LVEF: E2F2−/+=53±1%, E2F4−/+=61±2%, WT=75±1%, p&lt;0.05 vs. WT). Thus, downregulation of either E2F2 or E2F4 induced a phenotype similar to that of alpha−KI in response to TAC. To examine the causative role of E2F2/E2F4 downregulation in mediating the cardiac phenotype in alpha-KI mice, adenovirus (Ad) harboring either E2F2 or E2F4 was injected into alpha-KI hearts. Rescue with E2F2 or E2F4 attenuated cardiac hypertrophy (LVW/TL: alpha−KI+E2F2=7.1±0.4, alpha−KI+E2F4=7.3±0.3, alpha−KI+LacZ=8.7±0.4, p&lt;0.05 vs. alpha−KI+LacZ) and improved LV dysfunction (LVEF: alpha−KI+E2F2=66±3%, alpha−KI+E2F4=60±2%, alpha−KI+LacZ=39±2%, p&lt;0.05 vs. alpha−KI+LacZ) in alpha−KI mice under PO conditions. Injection of either Ad-E2F2 or Ad-E2F4, but not of Ad-LacZ, significantly increased the number of Ki67-positive myocytes in the alpha-KI mice (alpha-KI+LacZ =0.7±0.3%, alpha-KI+E2F2=10.4±2.3%, alpha-KI+E2F4=9.2±1.5%, p&lt;0.05 vs. alpha-KI+LacZ). These results suggest that maintaining the activity of E2F2 and E2F4 through S21 phosphorylation of GSK-3alpha plays an essential role in preserving cardiac function during PO.

Nebivolol Exerts Beneficial Effects on Endothelial Function, Early Endothelial Progenitor Cells, Myocardial Neovascularization, and Left Ventricular Dysfunction Early After Myocardial Infarction Beyond Conventional β1-Blockade

The aim of this study was to investigate whether nebivolol has added effects on left ventricular (LV) dysfunction and remodeling early after myocardial infarction (MI) beyond its β₁-receptor-blocking properties. Nebivolol is a third-generation selective β₁-adrenoreceptor antagonist that stimulates endothelial cell nitric oxide (NO) production and prevents vascular reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation. Both endothelial NO synthase-derived NO production and NADPH oxidase activation are critical modulators of LV dysfunction early after MI. Mice with extensive anterior MI (n = 90) were randomized to treatment with nebivolol (10 mg/kg/day), metoprolol-succinate (20 mg/kg/day), or placebo for 30 days starting on day 1 after surgery. Infarct size was similar among the groups. Both β₁-adrenergic receptor antagonists caused a similar decrease in heart rate. Nebivolol therapy improved endothelium-dependent vasorelaxation and increased early endothelial progenitor cells 4 weeks after MI compared with metoprolol and placebo. Nebivolol, but not metoprolol, inhibited cardiac NADPH oxidase activation after MI, as detected by electron spin resonance spectroscopy analysis. Importantly, nebivolol, but not metoprolol, improved LV dysfunction 4 weeks after MI (LV ejection fraction: nebivolol vs. metoprolol vs. placebo: 32 ± 4% vs. 17 ± 6% vs. 19 ± 4%; nebivolol vs. metoprolol: p < 0.05) and was associated with improved survival 4 weeks post-MI compared with placebo. Nebivolol had a significantly more pronounced inhibitory effect on cardiomyocyte hypertrophy after MI compared with metoprolol. Nebivolol improves LV dysfunction and survival early after MI likely beyond the effects provided by conventional β₁-receptor blockade. Nebivolol induced effects on NO-mediated endothelial function, early endothelial progenitor cells and inhibition of myocardial NADPH oxidase likely contribute to these beneficial effects of nebivolol early after MI.

Sildenafil increases chemotherapeutic efficacy of doxorubicin in prostate cancer and ameliorates cardiac dysfunction

We have shown that the potent phosphodiesterase-5 (PDE-5) inhibitor sildenafil (Viagra) induces a powerful effect on reduction of infarct size following ischemia/reperfusion injury and improvement of left ventricular dysfunction in the failing heart after myocardial infarction or doxorubicin (DOX) treatment. In the present study, we further investigated the potential effects of sildenafil on improving antitumor efficacy of DOX in prostate cancer. Cotreatment with sildenafil enhanced DOX-induced apoptosis in PC-3 and DU145 prostate cancer cells, which was mediated by enhanced generation of reactive oxygen species, up-regulation of caspase-3 and caspase-9 activities, reduced expression of Bcl-xL, and phosphorylation of Bad. Overexpression of Bcl-xL or dominant negative caspase 9 attenuated the synergistic effect of sildenafil and DOX on prostate cancer cell killing. Furthermore, treatment with sildenafil and DOX in mice bearing prostate tumor xenografts resulted in significant inhibition of tumor growth. The reduced tumor size was associated with amplified apoptotic cell death and increased expression of activated caspase 3. Doppler echocardiography showed that sildenafil treatment ameliorated DOX-induced left ventricular dysfunction. In conclusion, these results provide provocative evidence that sildenafil is both a powerful sensitizer of DOX-induced killing of prostate cancer while providing concurrent cardioprotective benefit.

Early Short-Term Vagal Nerve Stimulation Attenuates Cardiac Remodeling After Reperfused Myocardial Infarction

Background Vagal nerve stimulation (VS) has been suggested to be an effective adjunct to reperfusion therapy in myocardial infarction (MI). However, the effect of VS on left ventricular (LV) remodeling after reperfused MI has not been examined. Methods and Results We investigated the effects of early, brief VS on acute inflammatory reactions (study 1) and chronic LV remodeling (study 2) in a rabbit model of reperfused MI. In study 1, rabbits were subjected to 60-minute coronary artery occlusion followed by reperfusion alone (MI, n = 8) or treated with 24-hour VS (MI-VS, n = 8). At 24 hours after ischemia-reperfusion, MI-VS rabbits showed significantly decreased myocardial infiltration of neutrophils and reduced myocardial expressions of tumor necrosis factor-α and matrix metalloproteinase-8 and -9, compared with MI rabbits. Myocardial expression of interleukin-6 was not affected by VS. In study 2, rabbits were subjected to coronary occlusion and reperfusion alone (n = 16) or treated with VS for 3 days (n = 14). At 8 weeks after ischemia-reperfusion, MI-VS rabbits showed significantly improved LV dysfunction and dilatation, and significantly reduced infarct size, infarct wall thinning, and LV weight compared with MI rabbits. Conclusion Early, short-term VS attenuates LV remodeling after reperfused MI, which may be associated with suppression of acute inflammatory reactions.

Coronary reserve impairment prevents the improvement of left ventricular dysfunction and adversely affects the long-term outcome of patients with hypertensive dilated cardiomyopathy

In hypertension, left ventricular (LV) hypertrophy develops as an adaptive mechanism to compensate for increased afterload and thus preserve systolic function. Associated structural changes such as microvascular disease might potentially interfere with this mechanism, producing pathological hypertrophy. A poorer outcome is expected to occur when LV function is put in jeopardy by impaired coronary reserve. The aim of this study was to evaluate the role of coronary reserve in the long-term outcome of patients with hypertensive dilated cardiomyopathy. Between 1996 and 2000, 45 patients, 30 of them male, with 52 ± 11 years and LV fractional shortening <30% were enrolled and followed until 2006. Coronary flow velocity reserve was assessed by transesophageal Doppler of the left anterior descending coronary artery. Sixteen patients showed ≥10% improvement in LV fractional shortening after 17 ± 6 months. Coronary reserve was the only variable independently related to this improvement. Total mortality was 38% in 10 years. The Cox model identified coronary reserve (hazard ratio = 0.814; 95% CI = 0.72–0.92), LV mass, low diastolic blood pressure, and male gender as independent predictors of mortality. In hypertensive dilated cardiomyopathy, coronary reserve impairment adversely affects survival, possibly by interfering with the improvement of LV dysfunction.

Synthetic prostacycline agonist, ONO-1301, ameliorates left ventricular dysfunction and cardiac fibrosis in cardiomyopathic hamsters

Impairment of cardiac function in cardiomyopathy has been postulated to be related to decreased blood flow and increased collagen synthesis. Administration of growth factors was reported to attenuate left ventricular (LV) remodeling and dysfunction in animal models of dilated cardiomyopathy. We previously reported that ONO-1301, a synthetic prostacyclin agonist with thromboxane-synthase inhibitory activity, promotes production of hepatocyte growth factor and vascular endothelial growth factor from various cell types and ameliorate ischemia-induced LV dysfunction in mice and pigs. We evaluated therapeutic efficacy of ONO-1301 in the Syrian hamster (TO-2), a model of genetically determined dilated cardiomyopathy. Either vehicle or a slow releasing form of ONO-1301 (ONO-1301-PLGA, 10 mg/kg/3 weeks) was administered subcutaneously every 3 weeks to TO-2 hamsters from 24 to 32 weeks of age ( n = 12 for each group). Age-matched F1B hamsters were used as a control. Plasma concentration of HGF was elevated in ONO-1301-PLGA group ( p < 0.05). Echocardiographic study demonstrated that LV fractional shortening was significantly improved in the ONO-1301-PLGA group (25 ± 4%, p < 0.01) compared with that in the vehicle group (19 ± 2%). Cardiac fibrosis was significantly reduced by ONO-1301-PLGA ( p < 0.05) as determined by Azan-Mallory staining. Capillary density of left ventricle was markedly reduced in TO-2 hamsters. ONO-1301-PLGA significantly increased capillary density in TO-2 group ( p < 0.05). ONO-1301 improved LV dysfunction and reduced cardiac fibrosis in the hamster model of dilated cardiomyopathy. ONO-1301 might hold a therapeutic potential in the treatment of dilated cardiomyopathy.

QS9. Reduction of Infarction Area and Improvement of Left Ventricular Dysfunction by Omentopexy Combined With Granulocyte Colony-Stimulating Factor Administration in a Coronary Occlusion and Reperfusion Rabbit Model

QS9. Reduction of Infarction Area and Improvement of Left Ventricular Dysfunction by Omentopexy Combined With Granulocyte Colony-Stimulating Factor Administration in a Coronary Occlusion and Reperfusion Rabbit Model

Do Angiotensin-converting Enzyme Inhibitors and Angiotensin II Receptor Blockers Have Similar Effects in the Improvement of Left Ventricular Dysfunction after Myocardial Infarction in Japanese?

Do Angiotensin-converting Enzyme Inhibitors and Angiotensin II Receptor Blockers Have Similar Effects in the Improvement of Left Ventricular Dysfunction after Myocardial Infarction in Japanese?