Cardiac and hepatic role of r-AtHSP70: basal effects and protection against ischemic and sepsis conditions.

Heat shock proteins (HSPs), highly conserved in all organisms, act as molecular chaperones activated by several stresses. The HSP70 class of stress-induced proteins is the most studied subtype in cardiovascular and inflammatory disease. Because of the high similarity between plant and mammalian HSP70, the aim of this work was to evaluate whether recombinant HSP70 of plant origin (r-AtHSP70) was able to protect rat cardiac and hepatic function under ischemic and sepsis conditions. We demonstrated for the first time that, in ex vivo isolated and perfused rat heart, exogenous r-AtHSP70 exerted direct negative inotropic and lusitropic effects via Akt/endothelial nitric oxide synthase pathway, induced post-conditioning cardioprotection via Reperfusion Injury Salvage Kinase and Survivor Activating Factor Enhancement pathways, and did not cause hepatic damage. In vivo administration of r-AtHSP70 protected both heart and liver against lipopolysaccharide-dependent sepsis, as revealed by the reduced plasma levels of interleukin-1ß, tumour necrosis factor alpha, aspartate aminotransferase and alanine aminotransferase. These results suggest exogenous r-AtHSP70 as a molecular modulator able to protect myocardial function and to prevent cardiac and liver dysfunctions during inflammatory conditions.

Crucial role of phospholamban phosphorylation and S-nitrosylation in the negative lusitropism induced by 17ß-estradiol in the male rat heart.

BACKGROUND/AIMS: 17ß-estradiol (17ßE2) plays an important cardiovascular role by activating estrogen receptors (ER) α and ERß. Previous studies demonstrated that the novel estrogen G protein-coupled receptor (GPR30/GPER) mediates estrogen action in different tissues. We have recently shown in the rat heart that 17ßE2 elicits negative inotropism through ERα, ERß and GPR30, by triggering activation of ERK1/2, phosphatidylinositol 3-kinase (PI3K), protein kinase A (PKA) and endothelial Nitric Oxide synthase (eNOS) signaling. METHODS: In the present study, using the isolated and Langendorff-perfused rat heart as a model system we analyzed: i) whether and to which extent 17ßE2 modifies mammalian ventricular myocardial relaxation (lusitropism); ii) the type of ERs and the signaling pathways involved in this effect. RESULTS: We found that 17ßE2 negatively modulated the ventricular lusitropic performance. This effect, which partially involved the vascular endothelium, recruited ERß and occurred via PI3K, eNOS-NO-cGMP-protein kinase G (PKG) transduction cascade. Of note, 17ßE2-mediated negative lusitropism associated with a modification of phospholamban (PLN) phosphorylation and S-nitrosylation (SNO) both in isolated Langendorff rat heart and in isolated cardiomyocytes. CONCLUSION: Taken together, our results allow including 17ßE2 to the family of substances that control ventricular relaxation. This is of relevance in relation not only to the normal endocrine control of cardiac function, but also to physio-pathologic conditions characterized by an altered ventricular diastolic performance.

Endothelin-1 induces connective tissue growth factor expression in cardiomyocytes.

Endothelin (ET)-1 is a vasoconstrictor involved in cardiovascular diseases. Connective tissue growth factor/CCN2 (CTGF) is a fibrotic mediator overexpressed in human atherosclerotic lesions, myocardial infarction, and hypertension. In different cell types CTGF regulates cell proliferation/apoptosis, migration, and extracellular matrix (ECM) accumulation and plays important roles in angiogenesis, chondrogenesis, osteogenesis, tissue repair, cancer and fibrosis. In the present study, we investigated the ET-1 signaling which triggers CTGF expression in cultured adult mouse atrial-muscle HL-1 cells used as a model system. ET-1 activated the CTGF promoter and induced CTGF expression at both mRNA and protein levels. Real-time PCR analysis revealed CTGF induction also in isolated rat heart preparations perfused with ET-1. Several intracellular signals elicited by ET-1 via ET receptors and even Epidermal Growth Factor Receptor (EGFR) contributed to the up-regulation of CTGF, including ERK activation and induction of the AP-1 components c-fos and c-jun, as also evaluated by ChIP analysis. Moreover, in cells treated with ET-1 the expression of ECM component decorin was abolished by CTGF silencing, indicating that CTGF is involved in ET-1 induced ECM accumulation not only in a direct manner but also through downstream effectors. Collectively, our data indicate that CTGF could be a mediator of the profibrotic effects of ET-1 in cardiomyocytes. CTGF inhibitors should be considered in setting a comprehensive pharmacological approach towards ET-1 induced cardiovascular diseases.

Chromofungin, CgA47-66-derived peptide, produces basal cardiac effects and postconditioning cardioprotective action during ischemia/reperfusion injury.

Endogenous chromogranin A (CgA)-derived peptides are secreted by nervous, endocrine and immune cells. Chromofungin (Chr: CgA47-66) is one of these peptides that display antimicrobial activities and activate neutrophils, with important implications in inflammation and innate immunity. The aim of the present study is to examine the effects of Chr on isolated and Langendorff perfused rat hearts. The study was performed by using the isolated and Langendorff perfused rat hearts, Elisa assay and real-time PCR. We found that, under basal conditions, increasing doses (11-165nM) of Chr induced negative inotropic effects without changing coronary pressure. This action was mediated by the AKT/eNOS/cGMP/PKG pathway. We also found that Chr acted as a postconditioning (PostC) agent against ischemia/reperfusion (I/R) damages, reducing infarct size and LDH level. Cardioprotection involved PI3K, RISK pathway, MitoKATP and miRNA-21. We suggest that Chr directly affects heart performance, protects against I/R myocardial injuries through the activation of prosurvival kinases. Results may propose Chr as a new physiological neuroendocrine modulator able to prevent heart dysfunctions, also encouraging the clarification of its clinical potential.

Indenopyrazole oxime ethers: synthesis and ß1-adrenergic blocking activity.

This paper reports the synthesis and cardiac activity of new ß-blockers derived from (Z/E)-indeno[1,2-c]pyrazol-4(1H)-one oximes (5a,b). The latter compounds were allowed to react with epichlorohydrin, followed by reacting the oxiranyl derivatives formed (6a,b) with some aliphatic amines to give the target compounds (Z/E)-1-phenyl-1H-indeno[1,2-c]pyrazol-4-one O-((2-hydroxy-3-(substituted amino)propyl)oxime (7a-c) and (Z/E)-1-methyl-1H-indeno[1,2-c]pyrazol-4-one O-((2-hydroxy-3-(substituted amino)propyl)oxime (8a-c). These final products 7a-c and 8a-c were evaluated for their ability to modulate the cardiac performance of a prototype mammalian heart. The results showed that, out of these molecules tested, 7b elicits a more potent depressant effect on contractility and relaxation, and competitively antagonizes ß1-adrenergic receptors.

Malvidin, a red wine polyphenol, modulates mammalian myocardial and coronary performance and protects the heart against ischemia/reperfusion injury.

A moderate red wine consumption and a colored fruit-rich diet protect the cardiovascular system, thanks to the presence of several polyphenols. Malvidin-3-0-glucoside (malvidin), an anthocyanidine belonging to polyphenols, is highly present in red grape skin and red wine. Its biological activity is poorly characterized, although a role in tumor cell inhibition has been found. To analyze whether and to which extent, like other food-derived polyphenols, malvidin affects the cardiovascular function, in this study, we have performed a quantitative analysis by high-performance liquid chromatography of polyphenolic content of red grape skins extract, showing that it contains a high malvidin amount (63.93 ±12.50 mg/g of fresh grape skin). By using the isolated and Langendorff perfused rat heart, we found that the increasing doses (1-1000 ng/ml) of the extract induced positive inotropic and negative lusitropic effects associated with coronary dilation. On the same cardiac preparations, we observed that malvidin (10(-10)-10(-6) mol/L) elicited negative inotropism and lusitropism and coronary dilation. Analysis of mechanism of action revealed that malvidin-dependent cardiac effects require the activation of the phosphatidylinositol 3-kinase (PI3K)/nitric oxide (NO)/cGMP/PKG pathway and are associated with increased intracellular cGMP and the phosphorylation of endothelial NO synthase (eNOS), PI3K-AKT, ERK1/2, and GSK-3ß. AKT and eNOS phosphorylation was confirmed in human umbilical vein endothelial cell. We also found that malvidin act as a postconditioning agent, being able to elicit cardioprotection against ischemia/reperfusion damages. Our results show the cardioactivity of polyphenols-rich red grape extracts and indicate malvidin as a new cardioprotective principle. This is of relevance not only for a better clarification of the beneficial cardiovascular effects of food-derived polyphenols but also for nutraceutical research.

Cytoskeleton mediates negative inotropism and lusitropism of chromogranin A-derived peptides (human vasostatin1-78 and rat CgA1₋64) in the rat heart.

Cytoskeleton scaffold in cardiac myocytes provides structural support and compartmentalization of intracellular components. It is implicated in cardiac pathologies including hypertrophy and failure, playing a key role in the determinism of contractile and diastolic dysfunctions. Chromogranin A (CgA) and its derived peptides have revealed themselves as novel cardiovascular modulators. In humans, normal CgA levels considerably increase in several pathologies, including heart failure. Recent data have shown on the unstimulated rat heart that human recombinant Vasostatin-1 (hrVS-1) and rat chromogranin A 1-64 (rCgA1₋64) induce negative inotropic and lusitropic effects counteracting the ß-adrenergic-dependent positive inotropism with a functional non-competitive antagonism. This study investigates, on the isolated Langendorff perfused rat heart, whether cardiac cytoskeleton is involved in the modulation of contractility and relaxation exerted by hrVS-1 and rCgA1₋64. Cytoskeleton impairment by either cytochalasin-D (actin polymerization inhibitor), BDM (myosin ATP-ase antagonist) or wortmannin (inhibitor of PI3-K/Akt transduction cascade), or W-7 (calcium-calmodulin antagonist) abolished hrVS-1 and rCgA1₋64-mediated inotropism and lusitropism. Using fluorescent phalloidin, we showed on rat cardiac H9C2 cells that hrVS-1 (10 nM÷10 µM) stimulates actin polymerization. Taken together these data indicate that in the rat heart, the actin cytoskeletal network strongly contributes to the cardiotropic action of CgA-derived peptides.