Induction of Heparanase Gene Expression in Ventricular Myocardium of Rats with Isoproterenol-Induced Cardiac Hypertrophy

Heparanase Stimulation of Physiologic Cardiac Hypertrophy Is Suppressed After Chronic Diabetes, Resulting in Cardiac Remodeling and Dysfunction

In addition to controlling smooth muscle tone in coronary vessels, endothelial cells also influence subjacent cardiomyocyte growth. Because heparanase, with exclusive expression in endothelial cells, enables extracellular matrix remodeling, angiogenesis, metabolic reprogramming, and cell survival, it is conceivable that it could also encourage development of cardiac hypertrophy. Global heparanase overexpression resulted in physiologic cardiac hypertrophy, likely an outcome of HSPG clustering and activation of hypertrophic signaling. The heparanase autocrine effect of releasing neuregulin-1 could have also contributed to this overexpression. Hyperglycemia induced by streptozotocin-induced diabetes sensitized the heart to flow-induced release of heparanase and neuregulin-1. Despite this excess secretion, progression of diabetes caused significant gene expression changes related to mitochondrial metabolism and cell death that led to development of pathologic hypertrophy and heart dysfunction. Physiologic cardiac hypertrophy was also observed in rats with cardiomyocyte-specific vascular endothelial growth factor B overexpression. When perfused, hearts from these animals released significantly higher amounts of both heparanase and neuregulin-1. However, subjecting these animals to diabetes triggered robust transcriptome changes related to metabolism and a transition to pathologic hypertrophy. Our data suggest that in the absence of mechanisms that support cardiac energy generation and prevention of cell death, as seen after diabetes, there is a transition from physiologic to pathologic cardiac hypertrophy and a decline in cardiac function.

ARTICLE HIGHLIGHTS

Phosphocreatine Attenuates Isoproterenol-Induced Cardiac Fibrosis and Cardiomyocyte Apoptosis

The present study was designed to further explore the role and the underlying molecular mechanism of phosphocreatine (PCr) for cardiac fibrosis in vivo. Isoproterenol (ISO) was used to induce cardiac fibrosis in rats. PCr administration ameliorated fibrosis by reducing collagen accumulation and fibrosis-related signals, including transforming growth factor beta 1 (TGF-β1), alpha smooth muscle actin (α-SMA), collagen type I, and collagen type III. Mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B (NF-κB) signaling pathways, including p38, extracellular signal regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p65, were highly activated by ISO and blocked by PCr. Moreover, PCr decreased ISO-induced matrix metalloproteinase-9 (MMP-9) and increased the tissue inhibitor of metalloproteinase-1 (TIMP-1) expression. Furthermore, PCr suppressed cardiomyocyte apoptosis induced by ISO, as shown by downregulated expression of the proapoptotic caspase-3, Bax, and upregulated expression of the antiapoptotic Bcl-2. Taken together, PCr can be an effective agent for preventing cardiac fibrosis and cardiomyocyte apoptosis.

Liguzinediol protects against cardiac fibrosis in rats in vivo and in vitro

Cardiac fibrosis plays a causal role in the development of heart failure, and anti-fibrotic therapy represents a promising strategy to mitigate heart failure. The purpose of this study was to investigate the effect of a new drug-liguzinediol on cardiac fibrosis of heart failure Male Sprague-Dawley rats (SD) rats and the underlying mechanisms. Liguzinediol was administered to rats that were injected with doxorubicin (Dox) for four weeks. Two weeks later, its effects on cardiac fibrosis were assessed by haematoxylin and eosin (HE) staining and Masson staining. The collagen content was determined by Elisa, and protein expression was detected by western blot in vitro and in vivo. Liguzinediol decreased cardiac muscle fiber break evidenced by HE staining and it significantly reduced cardiac fibrosis evidenced by Masson staining in DOX-treated rats. In addition, the hydroxyproline level and the ratio of type I/III collagens were also significantly decreased, and western blot assays showed that liguzinediol regulated the balance between matrix matalloproteinases (MMPs) and tissue inhibitor of metalloproteinase (TIMPs) to protect cardiac remodeling in vivo and in vitro. These data collectively indicated that liguzinediol could protect against cardiac fibrosis in rats. Liguzinediol could be exploited to be a promising candidate for cardiac fibrosis.

Aberrant gene expression of heparanase in ventricular hypertrophy induced by monocrotaline in rats

The gene expression levels of heparanase, matrix metalloproteinase 2 (MMP2) and MMP9 were examined in ventricles after treatment with monocrotaline (MCT) to induce cardiac hypertrophy in rats. Rats received a single intraperitoneal injection of MCT (60 mg/kg) or saline. Twenty-five days after the injection, the right ventricle and lung wet weights were increased in MCT-treated rats compared with the control. Histological analysis revealed cardiomyocyte hypertrophy in the right ventricle of MCT-treated rats. Northern blot hybridization showed that heparanase and MMP2 expression increased significantly in the right and left ventricles of MCT-treated rats, whereas MMP9 was not induced. These findings indicate that heparanase and MMP2 might play an important role in the development of MCT-induced cardiac hypertrophy.

The relationship between the MMP system, adrenoceptors and phosphoprotein phosphatases

The MMPs and their inhibitors [tissue inhibitor of MMPs (TIMPs)] form the mainstay of extracellular matrix homeostasis. They are expressed in response to numerous stimuli including cytokines and GPCR activation. This review highlights the importance of adrenoceptors and phosphoprotein phosphatases (PPP) in regulating MMPs in the cardiovascular system, which may help explain some of the beneficial effects of targeting the adrenoceptor system in tissue remodelling and will establish emerging crosstalk between these three systems. Although α- and β-adrenoceptor activation increases MMP but decreases TIMP expression, MMPs are implicated in the growth stimulatory effects of adrenoceptor activation through transactivation of epidermal growth factor receptor. Furthermore, they have recently been found to catalyse the proteolysis of β-adrenoceptors and modulate vascular tone. While the mechanisms underpinning these effects are not well defined, reversible protein phosphorylation by kinases and phosphatases may be key. In particular, PPP (Ser/Thr phosphatases) are not only critical in resensitization and internalization of adrenoceptors but also modulate MMP expression. The interrelationship is complex as isoprenaline (ISO) inhibits okadaic acid [phosphoprotein phosphatase type 1/phosphoprotein phosphatase type 2A (PP2A) inhibitor]-mediated MMP expression. While this may be simply due to its ability to transiently increase PP2A activity, there is evidence for MMP-9 that ISO prevents okadaic acid-mediated expression of MMP-9 through a β-arrestin, NF-κB-dependent pathway, which is abolished by knock-down of PP2A. It is essential that crosstalk between MMPs, adrenoceptors and PPP are investigated further as it will provide important insight into how adrenoceptors modulate cardiovascular remodelling, and may identify new targets for pharmacological manipulation of the MMP system.

Spironolactone decreases isoproterenol-induced ventricular fibrosis and matrix metalloproteinase-2 in rats

Although transregulation between the sympathetic nervous system and the renin-angiotensin-aldosterone system has been reported, it remains unclear whether sympathetic hyperactivity-induced matrix metalloproteinease (MMP) expression/activity and cardiac fibrosis are mediated by the mineralocorticoid receptor system. We investigated whether isoproterenol (ISO)-induced MMP expression/activity and cardiac fibrosis are mediated by spironolactone in rats. Male Wistar Kyoto rats were divided into 3 groups: control, ISO, and ISO combined with spironolactone (SPI). ISO (2.0 mg/kg/d) and/or SPI (40 mg/kg/d) were given for 14 d. Echocardiography and hemodynamic measurements were recorded and hearts were excised. The myocyte cross-sectional and fibrotic area was evaluated via histopathological analysis. MMP-2 and collagen-I were analyzed by Western blotting and zymography. Compared with the controls, ISO significantly elevated the end-diastolic left ventricular (LV) pressure and the time constant of isovolumic relaxation and decreased the -dP/dt, while those of SPI co-treatment did not. ISO treatment induced significant increases in the fractional shortening and relative wall thickness, whereas SPI co-treatment significantly decreased relative wall thickness. Similarly, ISO significantly increased LV weight and myocyte cross-sectional and fibrotic area, which occurred concomitantly with the MMP-2 expression/activity and the expression of collagen-I. Moreover, ISO induced these features were significantly attenuated by SPI co-treatment. Our results suggest that ISO-evoked sympathetic hyperactivity induced LV fibrosis and MMP-2, which may be partially controlled via the mineralocorticoid receptor system.

Doxycycline attenuates isoproterenol-induced myocardial fibrosis and matrix metalloproteinase activity in rats

Our objective was to investigate the effects of doxycycline, a matrix metalloproteinase (MMP) inhibitor (MMPi) on beta-agonist-induced myocardial fibrosis and MMP expression. Twenly-four Wistar-Kyoto rats were divided into 3 groups: control (CTL; n=8), isoproterenol (ISO; n=8), and isoproterenol with doxycycline (ISO+DOX; n=8). ISO and ISO+DOX rats received L-isoproterenol (2.0 mg/kg/d) for 14 d, whereas the CTL group received vehicle. In addition, ISO+DOX rats received a subcutaneous injection of doxycycline (25 mg/kg/d) for 14 d, whereas CTL and ISO rats were injected with saline. Cardiac fibrosis was evaluated via histopathological analysis. MMP-2 and -9 were analyzed by Western blotting and zymography. Compared to the control, the myocardial cross-sectional area and areas of fibrosis were increased significantly in the ISO group, but were attenuated in the ISO+DOX group. MMP-2 activity also increased significantly in the ISO group, but decreased in the ISO+DOX group. Similarly, immunoblotting showed significant increase in MMP-2 and -9 levels in the ISO group, and decreased levels in the ISO+DOX group. Our results suggest that the enhanced expression of MMPs plays a prominent role in promoting myocardial fibrosis in beta-agonist signaling pathway, and that MMP-inhibiting compounds may attenuate myocardial fibrosis.

IL-17 induces myocardial fibrosis and enhances RANKL/OPG and MMP/TIMP signaling in isoproterenol-induced heart failure

OBJECTIVE

This study was designed to investigate whether IL-17 can regulate the expression of the MMP/TIMP system, the OPG/RANK/RANKL system, or type-I and type-III collagen fibers in a rat model of isoproterenol-induced heart failure (HF). We also investigated the effect of IL-17 on myocardial fibrosis in this model.

METHODS

HF was induced in Wistar-Kyoto rats by hypodermic injection of isoproterenol (ISO) twice every 24 h. After 2 months, the surviving rats were divided into three groups: monoclonal Anti-IL-17 Ab (100 microg/day), IgG (100 microg/day) or PBS were injected five times every 48 h (i.p.). One day after the last injection, all of the rats were sacrificed. H&E and Masson staining were used to evaluate myocardial fibrosis, and immunohistochemistry was used to measure the levels of MMP-1, TIMP-1, TIMP-4, OPG, RANKL, type-I and type-III collagen fibers. We also treated adult rat cardiac fibroblasts with IL-17 (10 ng/ml), IL-17 (10 ng/ml)+OPG (10 ng/ml), IL-17 (10 ng/ml)+anti-RANKL Ab (100 ng/ml), or PBS for 24 h, realtime RT-PCR was used to measure the expressions of MMP-1.

RESULTS

The expressions of MMP-1, RANKL, and type-I and -III collagen fibers decreased, and the expressions of TIMP-1, TIMP-4, and OPG increased in the Anti-IL-17 group compared to controls. H&E and Masson staining revealed that blockade of IL-17 can improve myocardial fibrosis in HF. IL-17 increased the expression of MMP-1 in cardiac fibroblasts, and OPG and anti-IL-17 Ab could inhibit this function partly. Thus, IL-17 was dependent on the RANKL/OPG system to induce MMP-1 partly.

CONCLUSION

Our study demonstrates the contribution of IL-17 to myocardial fibrosis in isoproterenol-induced HF. IL-17 can regulate the RANKL/OPG and MMP/TIMP systems in this model. The RANKL/OPG system is one of intermediaries between IL-17 and MMP-1 in cardiac fibroblasts. As a harmful cytokine, anti-IL-17 treatment is a potential therapeutic strategy in HF.

Long-term effects for acute phase myocardial infarct VEGF165 gene transfer cardiac extracellular matrix remodeling

BACKGROUND

Cardiac remodeling is ultimately regulated by components of the extracellular matrix (ECM). We investigated the important role that growth factors play in the regulation of ECM remodeling that occurs as a consequence of myocardium damage.

METHODS AND RESULTS

Rats were submitted to the ligation of the left anterior coronary artery and pcDNA3-vascular endothelial growth factor (VEGF)(165) was immediately injected intramyocardially in the treated group. The animals were divided into large size myocardium infarction (LMI) and small size myocardium infarction, with or without gene transfer. The plasmid-containing DNA encoding VEGF(165) was injected into the cardiac muscle and its effect was observed on the ECM components. Glycosaminoglycans were identified and quantified by agarose gel based electrophoresis and ELISA as well as immunocytochemistry to examine specific cathepsin B, heparanase, and syndecan-4 changes. The amounts of hyaluronic acid (HA; p < 0.005), DS, chondroitin sulfate, and heparan sulfate (p < 0.001) were significantly increased in the LMI treated group in comparison to the other groups, which correlates with the decrease in the expression of heparanase. A decrease in the molecular mass of HA was found in the scar tissue of treated group.

CONCLUSIONS

The data obtained strongly support the idea that changes in the ECM and its components are important determinants of cardiac remodeling after myocardium infarct and may be essential for inflammatory response and attempt to stabilize the damage and provide a compensatory mechanisms to maintain cardiac output since the ECM components analyzed are involved with angiogenesis, cell proliferation and differentiation.

Heparanase: a target for drug discovery in cancer and inflammation

The remodelling of the extracellular matrix (ECM) has been shown to be highly upregulated in cancer and inflammation and is critically linked to the processes of invasion and metastasis. One of the key enzymes involved in specifically degrading the heparan sulphate (HS) component of the ECM is the endo-beta-glucuronidase enzyme heparanase. Processing of HS by heparanase releases both a host of bioactive growth factors anchored within the mesh of the ECM as well as defined fragments of HS capable of promoting cellular proliferation. The finding that heparanase is elevated in a wide variety of tumor types and is subsequently linked to the development of pathological processes has led to an explosion of therapeutic strategies to inhibit its enzyme activity. So far only one compound, the sulphated oligosaccharide PI88, which both inhibits heparanase activity and has effects on growth factor binding has reached clinical trials where it has shown to have promising efficacy. The scene has clearly been set however for a new generation of compounds, either specific to the enzyme or with dual roles, to emerge from the lab and enter the clinic. The aim of this review is to describe the current drug discovery status of small molecule, sugar and neutralising antibody inhibitors of heparanase enzyme activity. Potential strategies will also be discussed on the selection of suitable biomarker strategies for specific monitoring of in vivo heparanase inhibition which will be crucial for both animal model and clinical trial testing.

Site specific differential activation of ras/raf/ERK signaling in rabbit isoproterenol-induced left ventricular hypertrophy

To understand better the mediating role of ras/raf/ERK signaling pathway in development of cardiac hypertrophy and cerebrovascular events in vivo, the molecular mechanism of the pathway in heart and cerebral arteries after isoproterenol (ISO) induced beta-adrenergic receptor (betaAR) stimulation was examined in rabbit as animal model. Compared with the heart, our findings indicate that ISO-stimulation results in increase in mRNA levels of ras, raf, and immediate-early genes in the cerebral arteries. Conversely, the ras and raf protein expression levels (determined by Western blot) and the ras-GTP level (determined by pull-down assay) in the heart, but not the cerebral arteries, are markedly elevated after treatment. In addition, despite constant ERK1/2 abundance, phosphorylated ERK (pERK) activity was elevated at both sites with prominent effect on heart following stimulation. Opposing to the PKA and PKC, as upstream contributors in the pathway, which seem to be similarly affected at both sites following ISO-stimulation, the results imply that the downstream candidates ras and raf, as well as immediate-early genes, have different responses at both sites post-stimulation. The results provide an evidence of site-dependent differential response of ras/raf/ERK pathway after cardiac hypertrophy-induced by ISO-stimulation. This varied response may account for underlying mechanisms of development of cardiac hypertrophy and cerebrovascular events in heart and cerebral arteries, respectively.