Disruption of hypoxia-inducible transcription factor-prolyl hydroxylase domain-1 (PHD-1-/-) attenuates ex vivo myocardial ischemia/reperfusion injury through hypoxia-inducible factor-1α transcription factor and its target genes in mice

Hypoxia-inducible transcription factor (HIF)-prolyl hydroxylases domain (PHD-1-3) are oxygen sensors that regulate the stability of the HIFs in an oxygen-dependent manner. Suppression of PHD enzymes leads to stabilization of HIFs and offers a potential treatment option for many ischemic disorders, such as peripheral artery occlusive disease, myocardial infarction, and stroke. Here, we show that homozygous disruption of PHD-1 (PHD-1(-/-)) could facilitate HIF-1α-mediated cardioprotection in ischemia/reperfused (I/R) myocardium. Wild-type (WT) and PHD-1(-/-) mice were randomized into WT time-matched control (TMC), PHD-1(-/-) TMC (PHD1TMC), WT I/R, and PHD-1(-/-) I/R (PHD1IR). Isolated hearts from each group were subjected to 30 min of global ischemia followed by 2 h of reperfusion. TMC hearts were perfused for 2 h 30 min without ischemia. Decreased infarct size (35%±0.6% vs. 49%±0.4%) and apoptotic cardiomyocytes (106±13 vs. 233±21 counts/100 high-power field) were observed in PHD1IR compared to wild-type ischemia/reperfusion (WTIR). Protein expression of HIF-1α was significantly increased in PHD1IR compared to WTIR. mRNA expression of β-catenin (1.9-fold), endothelial nitric oxide synthase (1.9-fold), p65 (1.9-fold), and Bcl-2 (2.7-fold) were upregulated in the PHD1IR compared with WTIR, which was studied by real-time quantitative polymerase chain reaction. Further, gel-shift analysis showed increased DNA binding activity of HIF-1α and nuclear factor-kappaB in PHD1IR compared to WTIR. In addition, nuclear translocation of β-catenin was increased in PHD1IR compared with WTIR. These findings indicated that silencing of PHD-1 attenuates myocardial I/R injury probably by enhancing HIF-1α/β-catenin/endothelial nitric oxide synthase/nuclear factor-kappaB and Bcl-2 signaling pathway.

Thioredoxin 1 enhances neovascularization and reduces ventricular remodeling during chronic myocardial infarction: a study using thioredoxin 1 transgenic mice

Oxidative stress plays a crucial role in disruption of neovascularization by alterations in thioredoxin 1 (Trx1) expression and its interaction with other proteins after myocardial infarction (MI). We previously showed that Trx1 has angiogenic properties, but the possible therapeutic significance of overexpressing Trx1 in chronic MI has not been elucidated. Therefore, we explored the angiogenic and cardioprotective potential of Trx1 in an in vivo MI model using transgenic mice overexpressing Trx1. Wild-type (W) and Trx1 transgenic (Trx1(Tg/+)) mice were randomized into W sham (WS), Trx1(Tg/+) sham (TS), WMI, and TMI. MI was induced by permanent occlusion of LAD coronary artery. Hearts from mice overexpressing Trx1 exhibited reduced fibrosis and oxidative stress and attenuated cardiomyocyte apoptosis along with increased vessel formation compared to WMI. We found significant inhibition of Trx1 regulating proteins, TXNIP and AKAP 12, and increased p-Akt, p-eNOS, p-GSK-3β, HIF-1α, β-catenin, VEGF, Bcl-2, and survivin expression in TMI compared to WMI. Echocardiography performed 30days after MI revealed significant improvement in myocardial functions in TMI compared to WMI. Our study identifies a potential role for Trx1 overexpression and its association with its regulatory proteins TXNIP, AKAP12, and subsequent activation of Akt/GSK-3β/β-catenin/HIF-1α-mediated VEGF and eNOS expression in inducing angiogenesis and reduced ventricular remodeling. Hence, Trx1 and other proteins identified in our study may prove to be potential therapeutic targets in the treatment of ischemic heart disease.

Inhibition of VEGF- and NO-dependent angiogenesis does not impair liver regeneration

Angiogenesis occurs through a convergence of diverse signaling mechanisms with prominent pathways that include autocrine effects of endothelial nitric oxide (NO) synthase (eNOS)-derived NO and vascular endothelial growth factor (VEGF). However, the redundant and distinct roles of NO and VEGF in angiogenesis remain incompletely defined. Here, we use the partial hepatectomy model in mice genetically deficient in eNOS to ascertain the influence of eNOS-derived NO on the angiogenesis that accompanies liver regeneration. While sinusoidal endothelial cell (SEC) eNOS promotes angiogenesis in vitro, surprisingly the absence of eNOS did not influence the angiogenesis that occurs after partial hepatectomy in vivo. While this observation could not be attributed to induction of alternate NOS isoforms, it was associated with induction of VEGF signaling as evidenced by enhanced levels of VEGF ligand in regenerating livers from mice genetically deficient in eNOS. However, surprisingly, mice that were genetically heterozygous for deficiency in the VEGF receptor, fetal liver kinase-1, also maintained unimpaired capacity for liver regeneration. In summary, inhibition of VEGF- and NO-dependent angiogenesis does not impair liver regeneration, indicating signaling redundancies that allow liver regeneration to continue in the absence of this canonical vascular pathway.

Postischemic deactivation of cardiac aldose reductase: role of glutathione S-transferase P and glutaredoxin in regeneration of reduced thiols from sulfenic acids

Aldose reductase (AR) is a multifunctional enzyme that catalyzes the reduction of glucose and lipid peroxidation-derived aldehydes. During myocardial ischemia, the activity of AR is increased due to the oxidation of its cysteine residues to sulfenic acids. It is not known, however, whether the activated, sulfenic form of the protein (AR-SOH) is converted back to its reduced, unactivated state (AR-SH). We report here that in perfused mouse hearts activation of AR during 15 min of global ischemia is completely reversed by 30 min of reperfusion. During reperfusion, AR-SOH was converted to a mixed disulfide (AR-SSG). Deactivation of AR and the appearance of AR-SSG during reperfusion were delayed in hearts of mice lacking glutathione S-transferase P (GSTP). In vitro, GSTP accelerated glutathiolation and inactivation of AR-SOH. Reduction of AR-SSG to AR-SH was facilitated by glutaredoxin (GRX). Ischemic activation of AR was increased in GRX-null hearts but was attenuated in the hearts of cardiospecific GRX transgenic mice. Incubation of AR-SSG with GRX led to the regeneration of the reduced form of the enzyme. In ischemic cardiospecific AR transgenic hearts, AR was co-immunoprecipitated with GSTP, whereas in reperfused hearts, the association of AR with GRX was increased. These findings suggest that upon reperfusion of the ischemic heart AR-SOH is converted to AR-SSG via GSTP-assisted glutathiolation. AR-SSG is then reduced by GRX to AR-SH. Sequential catalysis by GSTP and GRX may be a general redox switching mechanism that regulates the reduction of protein sulfenic acids to cysteines.

Thioredoxin-1 gene therapy enhances angiogenic signaling and reduces ventricular remodeling in infarcted myocardium of diabetic rats

BACKGROUND

The present study evaluated the reversal of diabetes-mediated impairment of angiogenesis in a myocardial infarction model of type 1 diabetic rats by intramyocardial administration of an adenoviral vector encoding thioredoxin-1 (Ad.Trx1). Various studies have linked diabetes-mediated impairment of angiogenesis to dysfunctional antioxidant systems in which thioredoxin-1 plays a central role.

METHODS AND RESULTS

Ad.Trx1 was administered intramyocardially in nondiabetic and diabetic rats immediately after myocardial infarction. Ad.LacZ was similarly administered to the respective control groups. The hearts were excised for molecular and immunohistochemical analysis at predetermined time points. Myocardial function was measured by echocardiography 30 days after the intervention. The Ad.Trx1-administered group exhibited reduced fibrosis, oxidative stress, and cardiomyocyte and endothelial cell apoptosis compared with the diabetic myocardial infarction group, along with increased capillary and arteriolar density. Western blot and immunohistochemical analysis demonstrated myocardial overexpression of thioredoxin-1, heme oxygenase-1, vascular endothelial growth factor, and p38 mitogen-activated protein kinase-beta, as well as decreased phosphorylated JNK and p38 mitogen-activated protein kinase-alpha, in the Ad.Trx1-treated diabetic group. Conversely, we observed a significant reduction in the expression of vascular endothelial growth factor in nondiabetic and diabetic animals treated with tin protoporphyrin (SnPP, a heme oxygenase-1 enzyme inhibitor), even after Ad.Trx1 therapy. Echocardiographic analysis after 4 weeks of myocardial infarction revealed significant improvement in myocardial functional parameters such as ejection fraction, fractional shortening, and E/A ratio in the Ad.Trx1-administered group compared with the diabetic myocardial infarction group.

CONCLUSIONS

This study demonstrates for the first time that impairment of angiogenesis and myocardial dysfunction can be regulated by Ad.Trx1 gene therapy in streptozotocin-induced diabetic rats subjected to infarction.

Coadministration of adenoviral vascular endothelial growth factor and angiopoietin-1 enhances vascularization and reduces ventricular remodeling in the infarcted myocardium of type 1 diabetic rats

OBJECTIVE

Hyperglycemia impairs angiogenesis in response to ischemia, leading to ventricular remodeling. Although the effects of overexpressing angiogenic growth factors have been studied in inducing angiogenesis, the formation of functional vessels remains a challenge. The present study evaluates the reversal of diabetes-mediated impairment of angiogenesis in the infarcted diabetic rat myocardium by proangiogenic gene therapy.

RESEARCH DESIGN AND METHODS

Ad*VEGF and Ad*Ang1 were intramyocardially administered in combination immediately after myocardial infarction to nondiabetic and diabetic rats. Ad*LacZ was similarly administered to the respective control groups. The hearts were excised for molecular and immunohistochemical analysis at predetermined time points. The myocardial function was measured by echocardiography 30 days after the intervention.

RESULTS

We observed reduced fibrosis and increased capillary/arteriolar density along with reduced ventricular remodeling, as assessed by echocardiography in the treated diabetic animals compared with the nontreated diabetic controls. We also observed increased phosphorylated mitogen-activated protein kinase-activated protein kinase-2, 2 days after the treatment and increased expression of vascular endothelial growth factor (VEGF), Flk-1, angiopoietin-1 (Ang-1), Tie-2, and survivin, 4 days after treatment in the diabetic animals. Gel shift analysis revealed that the combination gene therapy stimulated the DNA binding activity of nuclear factor-kappaB in the diabetic animals.

CONCLUSIONS

Our preclinical data demonstrate the efficacy of coadministration of adenoviral VEGF and Ang-1 in increasing angiogenesis and reducing ventricular remodeling in the infarcted diabetic myocardium. These unique results call for the initiation of a clinical trial to assess the efficacy of this therapeutic strategy in the treatment of diabetes-related human heart failure.

Mesenchymal stem cell: present challenges and prospective cellular cardiomyoplasty approaches for myocardial regeneration

Myocardial ischemia and cardiac dysfunction have been known to follow ischemic heart diseases (IHDs). Despite a plethora of conventional treatment options, their efficacies are associated with skepticism. Cell therapies harbor a promising potential for vascular and cardiac repair, which is corroborated by adequate preclinical evidence. The underlying objectives behind cardiac regenerative therapies subsume enhancing angiomyogenesis in the ischemic myocardium, ameliorating cellular apoptosis, regenerating the damaged myocardium, repopulating the lost resident myocardial cells (smooth muscle, cardiomyocyte, and endothelial cells), and finally, decreasing fibrosis with a consequent reduction in ventricular remodeling. Although-cell based cardiomyoplasty approaches have an immense potential, their clinical utilization is limited owing to the increased need for better candidates for cellular cardiomyoplasty, better routes of delivery, appropriate dose for efficient engraftment, and better preconditioning or genetic-modification strategies for the progenitor and stem cells. Mesenchymal stem cells (MSCs) have emerged as powerful candidates in mediating myocardial repair owing to their unique properties of multipotency, transdifferentiation, intercellular connection with the resident cardiomyocytes via connexin 43 (Cx43)-positive gap junctions in the myocardium, and most important, immunomodulation. In this review, we present an in-depth discussion on the complexities associated with stem and progenitor cell therapies, the potential of preclinical approaches involving MSCs for myocardial repair, and an account of the past milestones and ongoing MSC-based trials in humans.

Resveratrol enhances GLUT-4 translocation to the caveolar lipid raft fractions through AMPK/Akt/eNOS signalling pathway in diabetic myocardium

Homeostasis of blood glucose by insulin involves stimulation of glucose uptake by translocation of glucose transporter Glut-4 from intracellular pool to the caveolar membrane system. In this study we examined resveratrol (RSV)-mediated Glut-4 translocation in the streptozotocin (STZ)-induced diabetic myocardium. The rats were randomized into three groups: Control (Con), Diabetes Mellitus (DM) (STZ 65 mg/kg b.w., i.p.) & DM + RSV (2.5 mg/kg b.wt. for 2 weeks orally) (RSV). Isolated rat hearts were used as per the experimental model. RSV induced glucose uptake was observed in vitro with H9c2 cardiac myoblast cells. Decreased blood glucose level was observed after 30 days (375 mg/dl) in RSV-treated rats when compared to DM (587 mg/dl). Treatment with RSV demonstrated increased Adenosine Mono Phosphate Kinase (AMPK) phosphorylation compared to DM. Lipid raft fractions demonstrated decreased expression of Glut-4, Cav-3 (0.4, 0.6-fold) in DM which was increased to 0.75-and 1.1-fold on RSV treatment as compared to control. Increased Cav-1 expression (1.4-fold) in DM was reduced to 0.7-fold on RSV treatment. Increased phosphorylation of endothelial Nitric Oxide Synthase (eNOS) & Akt was also observed in RSV compared to DM (P< 0.05). Confocal microscopy and co-immunoprecipitation studies demonstrated decreased association of Glut-4/Cav-3 and increased association of Cav-1/eNOS in DM as compared to control and converse results were obtained on RSV treatment. Our results suggests that the effect of RSV is non-insulin dependent and triggers some of the similar intracellular insulin signalling components in myocardium such as eNOS, Akt through AMPK pathway and also by regulating the caveolin-1 and caveolin-3 status that might play an essential role in Glut-4 translocation and glucose uptake in STZ- induced type-1 diabetic myocardium.

Resveratrol: a promising agent in promoting cardioprotection against coronary heart diseaseThis article is one of a selection of papers from the NATO Advanced Research Workshop on Translational Knowledge for Heart Health (published in part 2 of a 2-part Special Issue)

The inverse association between alcohol intake and coronary heart disease has been consistently reported in cross-culture, case–control, and cohort studies. Over the past couple of decades, however, many studies have explained promising health benefits associated with wine consumption. Some studies suggest that red wine is more cardioprotective than white wine, possibly due to the increased content of flavanoid antioxidants found in red wine. Several experimental studies, including ours, support the evidence that these beneficial effects are due to resveratrol, the polyphenolic compound present in red wine. Many studies have provided evidence that resveratrol possesses antioxidant and antiapoptotic effects apart from activation of longevity proteins (such as SIRT-1). We have recently reported the angiogenic, antihypercholesterolemic, and antidiabetic effects of resveratrol and the mechanisms involved in reduced ventricular remodeling and increased cardiac functions. We have also shown different strategic target molecules involved in resveratrol-mediated cardioprotection. Therefore, this review discusses the potential effect of resveratrol and the mechanisms involved in resveratrol-mediated cardioprotection during myocardial infarction, hypercholesterolemia, and diabetes rendering its beneficial effects during health and disease.

NV1FGF, a pCOR plasmid-based angiogenic gene therapy for the treatment of intermittent claudication and critical limb ischemia

Gene transfer of FGF1 has been demonstrated to successfully promote angiogenesis. NV1FGF, a novel pCOR (conditional origin of replication) DNA plasmid-based gene delivery system, is in development by Sanofi-Aventis for the local expression of FGF1 in the treatment of peripheral vascular disease, and has demonstrated potential to induce therapeutic angiogenesis. Preclinical studies using NV1FGF demonstrated restoration in capillary and arteriolar density in rabbit and hamster models of hind limb ischemia. In phase I and phase II clinical trials, NV1FGF effectively reduced the number of amputations and deaths in the trials, with minimal toxicity, and in conjunction with a sustained increase in mRNA and protein levels of FGF1 and its receptors in patients with critical limb ischemia (CLI). These results prompted a phase III trial of NV1FGF in patients with CLI, with the aim of improving quality of life. Thus, the results of the phase III clinical trial may be a significant advancement in the field of medical science, widening the reach of this therapeutic approach to effectively cure intermittent claudication and CLI.

Bromelain treatment reduces CD25 expression on activated CD4+ T cells in vitro

Bromelain (Br), an extract from pineapple stem with cysteine protease activity, exerts anti-inflammatory effects in a number of inflammatory models. We have previously shown that Br treatment decreased activated CD4(+) T cells and has a therapeutic role in an ovalbumin-induced murine model of allergic airway disease. The current study was designed to determine the effect of Br on CD4(+) T cell activation, specifically the expression of CD25 in vitro. CD25 is up regulated upon T cell activation, found as a soluble fraction (sCD25) and is a therapeutic target in inflammation, autoimmunity and allergy. Br treatment of anti-CD3 stimulated CD4(+) T cells reduced CD25 expression in a dose and time dependent manner. This reduction of CD25 was dependent on the proteolytic action of Br as the addition of E64 (a cysteine protease inhibitor) abrogated this response. The concentration of sCD25 was increased in supernatants of Br treated activated CD4(+) T cells as compared to control cells, suggesting that Br proteolytically cleaved cell-surface CD25. This novel mechanism of action identifies how Br may exert its therapeutic benefits in inflammatory conditions.

Ex vivo and in vivo approaches to study mechanisms of cardioprotection targeting ischemia/reperfusion (i/r) injury: useful techniques for cardiovascular drug discovery

The last few decades have seen significant advancement in the therapy of Ischemic Heart Diseases (IHD). This is a direct outcome of the increasing knowledge of the molecular mechanisms involved during an ischemic insult of the myocardium. Even then there is still a major unmet need for better strategies or drug therapies to reduce ventricular remodeling and improve post-ischemic myocardial function. The ex-vivo isolated working heart model and the in vivo myocardial infarction model are the best known techniques to elucidate the contribution of a drug therapy to confer cardioprotection in the event of an ischemic insult/reperfusion. Our review aims to provide an insight into the state of the art techniques that lay the foundations for cardiovascular drug discovery and present the prospects for further development from a preclinical perspective. The first section of the review provides an overview of the rat/mouse ex-vivo and in vivo models of myocardial ischemia. The following section will then present various applications of these clinically relevant models in characterizing cardiac functions, screening for drugs and identifying the drug induced changes in cardiac functions. Finally the role of these models in drug development is discussed with respect to functional relevance of drug treatment on heart rate, aortic flow, coronary flow, infarct size and the mechanisms by which these drugs promote myocardial protection. This review may serve as a basic knowledge for researchers who intend to study the efficacy of a drug in the treatment of ischemic heart diseases.

Niacin bound chromium treatment induces myocardial Glut-4 translocation and caveolar interaction via Akt, AMPK and eNOS phosphorylation in streptozotocin induced diabetic rats after ischemia-reperfusion injury

Diabetes, one of the major risk factors of metabolic syndrome culminates in the development of Ischemic Heart Disease (IHD). Refined diets that lack micronutrients, mainly trivalent chromium (Cr(3+)) have been identified as the contributor in the rising incidence of diabetes. We investigated the effect of niacin-bound chromium (NBC) during ischemia/reperfusion (IR) injury in streptozotocin induced diabetic rats. Rats were randomized into: Control (Con); Diabetic (Dia) and Diabetic rats fed with NBC (Dia+NBC). After 30 days of treatment, the isolated hearts were subjected to 30 min of global ischemia followed by 2 h of reperfusion. NBC treatment demonstrated significant increase in left ventricular functions and significant reduction in infarct size and cardiomyocyte apoptosis in Dia+NBC compared with Dia. Increased Glut-4 translocation to the lipid raft fractions was also observed in Dia+NBC compared to Dia. Reduced Cav-1 and increased Cav-3 expression along with phosphorylation of Akt, eNOS and AMPK might have resulted in increased Glut-4 translocation in Dia+NBC. Our results indicate that the cardioprotective effect of NBC is mediated by increased activation of AMPK, Akt and eNOS resulting in increased translocation of Glut-4 to the caveolar raft fractions thereby alleviating the effects of IR injury in the diabetic myocardium.

Sildenafil augments early protective transcriptional changes after ischemia in mouse myocardium

Recently, targeting cyclic-GMP specific phosphodiesterase-5 (PDE5) has attracted much interest in several cardiopulmonary diseases, in particular myocardial ischemia (MI). Although multiple mechanisms were postulated for these beneficial effects at cellular level, early transcriptional changes were unknown. The aim of present study was to examine gene expression profiles in response to MI after 24 h of ischemia in murine model and compare transcriptional modulation by sildenafil, a popular phosphodiesterase 5 (PDE5) inhibitor. Mice were divided into four groups: Control sham (C), Sildenafil sham (S), Control MI (CMI) and Sildenafil MI (SMI). Sildenafil was given at a dose of 0.7 mg/kg intraperitoneally 30 min before LAD occlusion. cDNA microarray analysis of peri-infarct tissue was done using a custom cloneset and employing a looped dye swap design. Replicate signals were median averaged and normalized using LOWESS algorithm. R/MAANOVA analysis was used and false discovery rate corrected permutation p-values <0.005 were employed as significance thresholds. 156 genes were identified as significantly regulated demonstrating fold difference >1.5 in at least one of the four groups. 52 genes were significantly upregulated in SMI compared to CMI. For a randomly chosen subset of genes (9), microarray data were confirmed through real time RT-PCR. The differentially expressed genes could be classified into following groups based on their function: phosphorylation/dephosphorylation, apoptosis, differentiation, ATP binding. Our results suggest that sildenafil treatment might regulate early genetic reprogramming strategy for preservation of the ischemic myocardium.

Akt/FOXO3a/SIRT1-mediated cardioprotection by n-tyrosol against ischemic stress in rat in vivo model of myocardial infarction: switching gears toward survival and longevity

Moderate consumption of wine has been associated with decreased risk of cardiovascular events. Recently we have shown that white wine is equally as cardioprotective as red wine. However, unlike resveratrol (polyphenol in red wine), the white wine component, n-tyrosol [2-(4-hydroxyphenyl)ethanol] has not been explored for its cardioprotective effect and mechanism of action. Therefore, the present study was designed to evaluate the effect of tyrosol treatment (5 mg/kg/day for 30 days) on myocardial ischemic stress in a rat in vivo model of Myocardial Infarction (MI) and to identify key molecular targets involved in this mechanism. MI was induced by Left Anterior Descending (LAD) coronary artery ligation. Reduced infarct size (32.42 vs 48.03%) and cardiomyocyte apoptosis (171 vs 256 counts/100 HPF) were observed along with improvement in the myocardial functional parameters such as LVIDs (5.89 vs 6.58 mm), ejection fraction (51.91 vs 45.09%), and fractional shortening (28.46 vs 23.52%) as assessed by echocardiography in the tyrosol-treated animals when compared to the nontreated controls. We have also observed significant increase in the phosphorylation of Akt (1.4-fold), eNOS (3-fold) and FOXO3a (2.6-fold). In addition, tyrosol induced the expression of longevity protein SIRT1 (3.2-fold) in the MI group as compared to the non-treated MI control. Therefore tyrosol's SIRT1, Akt and eNOS activating power adds another dimension to the white wine research, because it adds a great link to the French paradox. In conclusion these findings suggest that tyrosol induces myocardial protection against ischemia related stress by inducing survival and longevity proteins that may be considered as anti-aging therapy for the heart. However, human intervention studies would be necessary before establishing any recommendations about dietary habits for tyrosol intake or administration of dietary supplements containing tyrosol.

Strategic targets to induce neovascularization by resveratrol in hypercholesterolemic rat myocardium: role of caveolin-1, endothelial nitric oxide synthase, hemeoxygenase-1, and vascular endothelial growth factor

Endothelial dysfunction and impaired angiogenesis constitute a hallmark of hypercholesterolemia. This study was designed to examine the effects of resveratrol, an antioxidant with lipid-lowering properties similar to those of statins, on neovascularization along with caveolar interaction with proangiogenic molecules in hypercholesterolemic rats. Animals were divided into: rats maintained on a normal diet (control group); rats maintained on a 5% high-cholesterol diet for 8 weeks (HC group); and rats maintained on a 5% high-cholesterol diet for 8 weeks and administered resveratrol (20 mg/kg) orally for 2 weeks (HCR group). Myocardial infarction was induced by ligating the left anterior descending artery. Herein we examined a novel method for stimulating myocardial angiogenesis by pharmacological preconditioning with resveratrol at both the capillary and arteriolar levels and the potential role of hemeoxygenase-1, endothelial nitric oxide synthase and caveolin-1 in mediating such a response. We also investigated the functional relevance of such treatment by assessing whether the induced neovascularization can help preserve left ventricle-contractile functional reserve in the setting of a chronic hypercholesterolemic condition. Four weeks after sham surgery and left anterior descending artery occlusion, rats underwent echocardiographic evaluation, which revealed improvement in ejection fraction and fractional shortening in the HCR group compared with the HC group. Left ventricular tissue sections displayed increased capillary and arteriolar density in the HCR group compared with the HC group. Western blot analysis revealed downregulation of vascular endothelial growth factor and hemeoxygenase-1 and increased association of caveolin-1 eNOS in the HC group, decreasing the availability of eNOS to the system; which was reversed with resveratrol treatment in the HCR group. This study was further validated in cardiac-specific hemeoxygenase-1-overexpressed mice assuming molecular cross-talk between the targets. Hence, our data identified potential regulators that primarily attenuate endothelial dysfunction by resveratrol therapy in hypercholesterolemic myocardium.

White wine induced cardioprotection against ischemia-reperfusion injury is mediated by life extending Akt/FOXO3a/NFkappaB survival pathway

Recent studies on the protection afforded by moderate wine consumption against cardiovascular diseases have focused mainly on the activity of red wine in view of its high content of antioxidants, especially polyphenols. White wine lacks polyphenols, but it contains other compounds such as hydroxycinnamic acids (caffeic acid) and monophenols (tyrosol), which are known to have antioxidant properties. Therefore, this study was designed to examine the effect of white wine in myocardial ischemic-reperfusion injury. The experimental rats were gavaged with white wine (Soave Suavia "Le Rive" 2004) at a dosage of 6.5 mL/(kg.rat.day) for 30 days. Rats were divided into four groups: control sham (CS), wine-treated sham (WS), control ischemia (I)/reperfusion (R) (CIR), and wine + IR (WIR). All the rats in both IR groups underwent 30 min occlusion of the left anterior descending coronary artery followed by 8, 24 h, and 30 days of reperfusion (R). Significant reduction in infarct size (21 vs 39%, n = 6), cardiomyocyte (274 vs 384 counts/100 HPF, n = 6), and endothelial cell apoptosis (387 vs 587 counts/100 HPF) was observed in WIR as compared with CIR after 24 h of reperfusion. Echocardiography demonstrated significant increased fractional shortening (32 vs 22%) and ejection fraction (60 vs 44%) following 30 days of reperfusion in WIR rats compared to CIR ( n = 6). In addition, increased phosphorylation of AKT, Foxo3a, and eNOS were found in WS and WIR, as compared to their respective controls. The gel-shift analysis demonstrated significant upregulation of DNA binding activity of NF-kappaB in the white wine-treated groups. This report demonstrated for the first time that the white wine mediated cardioprotection in ischemic reperfused myocardium is through the PI-3kinase/Akt/FOXO3a/e-NOS/NF-kappaB survival pathway.

Adeno-sh-beta-catenin abolishes ischemic preconditioning-mediated cardioprotection by downregulation of its target genes VEGF, Bcl-2, and survivin in ischemic rat myocardium

beta-Catenin, the downstream target of glycogen synthase kinase-3beta (GSK-3beta), plays a vital role in ischemic preconditioning (IP)-mediated cardioprotection. In the present study, we investigated the mechanism of IP-mediated cardioprotection through suppression of beta-catenin expression by intramyocardial injection of adeno-sh-RNA against beta-catenin (BCT) (4 x 10(8) pfu). Adeno-LacZ (LZ) was used as control. The rats were randomized into (a) LZ + ischemia-reperfusion (IR); (b) LZIPIR; (c) BCTIR; and (d) BCTIPIR. Isolated hearts from each group were subjected to 30 min of I followed by 2 h of R. Both IPIR group hearts were subjected to IP (5 min I + 10 min R; four cycles) before IR. Significant reduction in left ventricular functional recovery (78 vs. 88 mm Hg), dp/dt(max) (1,802 vs. 2,189 mm Hg/sec), and aortic flow (4 vs. 9 ml/min) was observed in BCTIPIR compared with LZIPIR at 120 min of reperfusion. Increased infarct size (42 vs. 24%) and apoptotic cardiomyocytes (122 vs. 58 counts/60 HPF) were observed in BCTIPIR compared with LZIPIR. Realtime PCR and Western blot analysis showed significant downregulation in mRNA and protein expression of VEGF, Bcl-2, and survivin in BCTIPIR compared with LZIPIR. These findings indicated for the first time that silencing beta-catenin abolished IP-mediated cardioprotection, probably through inhibition of VEGF-Bcl-2 and survivin.

Sildenafil-mediated neovascularization and protection against myocardial ischaemia reperfusion injury in rats: role of VEGF/angiopoietin-1

Sildenafil citrate (SC), a drug for erectile dysfunction, is now emerging as a cardiopulmonary drug. Our study aimed to determine a novel role of sildenafil on cardioprotection through stimulating angiogenesis during ischaemia (I) reperfusion (R) at both capillary and arteriolar levels and to examine the role of vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang-1) in this mechanistic effect. Rats were divided into: control sham (CS), sildenafil sham (SS), control + IR (CIR) and sildenafil + IR (SIR). Rats were given 0.7 mg/kg, (i.v) of SC or saline 30 min. before occlusion of left anterior descending artery followed by reperfusion (R). Sildenafil treatment increased capillary and arteriolar density followed by increased blood flow (2-fold) compared to control. Treatment with sildenafil demonstrated increased VEGF and Ang-1 mRNA after early reperfusion. PCR data were validated by Western blot analysis. Significant reduction in infarct size, cardiomyocyte and endothelial apoptosis were observed in SC-treated rats. Increased phosphorylation of Akt, eNOS and expression of anti-apoptotic protein Bcl-2, and thioredoxin, hemeoxygenase-1 were observed in SC-treated rats. Echocardiography demonstrated increased fractional shortening and ejection fraction following 45 days of reperfusion in the treatment group. Stress testing with dobutamine infusion and echocardiogram revealed increased contractile reserve in the treatment group. Our study demonstrated for the first time a strong additional therapeutic potential of sildenafil by up-regulating VEGF and Ang-1 system, probably by stimulating a cascade of events leading to neovascularization and conferring myocardial protection in in vivo I/R rat model.

Bromelain induces cardioprotection against ischemia-reperfusion injury through Akt/FOXO pathway in rat myocardium

Bromelain (Br), a proteolytic enzyme extracted from the stem of the pineapple, is known to possess anti-inflammatory activity and has been shown to reduce blood viscosity, prevent the aggregation of blood platelets, and improve ischemia-reperfusion (I/R) injury in a skeletal muscle model. We investigated the capacity of Br to limit myocardial injury in a global I/R model. Adult male Sprague-Dawley rats were divided into two groups: control (PBS) and Br at 10 mg/kg in PBS administered via intraperitoneal injection (twice/day) for 15 consecutive days. On day 16, the hearts were excised and subjected to 30 min of global ischemia followed by 2 h of reperfusion. Br treatment showed higher left ventricular functional recovery throughout reperfusion compared with the controls [maximum rate of rise in intraventricular pressure (dP/d tmax), 2,225 vs. 1,578 mmHg/s at 2 h reperfusion]. Aortic flow was also found to be increased in Br treatment when compared with that in untreated rats (11 vs. 1 ml). Furthermore, Br treatment reduced both the infarct size (34% vs. 43%) and the degree of apoptosis (28% vs. 37%) compared with the control animals. Western blot analysis showed an increased phosphorylation of both Akt and FOXO3A in the treatment group compared with the control. These results demonstrated for the first time that Br triggers an Akt-dependent survival pathway in the heart, revealing a novel mechanism of cardioprotective action and a potential therapeutic target against I/R injury.