Novel approaches to retard ventricular remodeling in heart failure

Cardiovascular Diseases and Zinc

Zinc is structurally and functionally essential for more than 300 enzymes and 2000 transcription factors in human body. Intracellular labile zinc is the metabolically effective zinc and tiny changes in its concentrations significantly affect the intracellular signaling and enzymatic responses. Zinc is crucial for the embrionic and fetal development of heart. Therefore, it is shown to be related with a variety of congenital heart defects. It is involved in epithelial-to-mesenchymal transformation including endocardial cushion development, which is necessary for atrioventricular septation as well as the morphogenesis of heart valves. In atherosclerosis, monocyte endothelial adhesion, and diapedesis, activation and transformation into macrophages and forming foam cells by the ingestion of oxidized LDL are monocyte related steps which need zinc. Intracellular zinc increases intracellular calcium through a variety of pathways and furthermore, zinc itself can work as a second messenger as calcium. These demonstrate the significance of intracellular zinc in heart failure and arterial hypertension. However, extracellular zinc has an opposite effect by blocking calcium channels, explaining decreased serum zinc levels, contrary to the increased cardiomyocyte and erythrocyte zinc levels in hypertensive subjects. These and other data in the literature demonstrate that zinc has important roles in healthy and diseased cardiovascular system but zinc-cardiovascular system relationship is so complex that, it has not been explained in all means. In this article, we try to review some of the available knowledge about this complex relationship.

How to protect doxorubicin-induced cardiomyopathy in male albino rats?

The present study was designed to compare the cardioprotective effects of the combination of lisinopril with growth hormone over lisinopril alone in doxorubicin (Dox)-induced cardiomyopathy in rats. Forty male Wister albino rats were divided into 4 groups: group 1, control group; group 2, received Dox; group 3, received lisinopril + Dox; and group 4, received lisinopril + Dox + growth hormone. Dox (cumulative dose) was administered to rats in 6 equal intraperitoneal injections over a period of 2 weeks. Histopathological changes and plasma aspartate aminotransferase, lactate dehydrogenase, and creatine kinase and plasma levels of matrix metalloproteinase (MMP)-2, tissue inhibitor matrix metalloproteinase (TIMP)-1, and cardiac inducible nitric oxide synthase (iNOS) messenger RNA (mRNA) expression were determined 9 weeks after the first dose of Dox. Dox produced cardiac structural injury and significant elevation in plasma levels of cardiac enzymes, MMP-2, and cardiac iNOS mRNA expression together with significant reduction in plasma TIMP-1 level. Lisinopril significantly decreases plasma MMP-2 level and cardiac iNOS mRNA expression by 13% and 15%, respectively, in group 3 compared with 36% and 47%, respectively, in group 4 as compared with group 2. In addition, compared with Dox group, lisinopril significantly increases plasma TIMP-1 level by 23% compared with 49% in group 4. We can conclude that the combination of lisinopril and growth hormone produced better cardioprotective effect against Dox-induced cardiomyopathy. This effect may be attributed on their antiremodeling actions by regulating plasma MMP-2/TIMP-1 levels and to the reduction of cardiac iNOS mRNA expression.

c-Jun DNAzymes Inhibit Myocardial Inflammation, ROS Generation, Infarct Size, and Improve Cardiac Function After Ischemia-Reperfusion Injury

Objectives— Coronary reperfusion has been the mainstay therapy for reduced infarct size after a heart attack. However, this intervention also results in myocardial injury by initiating a marked inflammatory reaction, and new treatments are keenly sought.

Methods and Results— The basic-region leucine zipper protein, c-Jun is poorly expressed in the normal myocardium and is induced within 24 hours after myocardial ischemia-reperfusion injury. Synthetic catalytic DNA molecules (DNAzymes) targeting c-Jun (Dz13) reduce infarct size in the area-at-risk (AAR) regardless of whether it is delivered intramyocardially at the initiation of ischemia or at the time of reperfusion. Dz13 attenuates neutrophil infiltration, c-Jun and ICAM-1 expression in vascular endothelium, cardiomyocyte apoptosis, and the generation of reactive oxygen species in the reperfused myocardium. It inhibits infiltration into the AAR of complement 3 (C3), C3a receptor (C3aR), membrane attack complex-1 (Mac-1), or matrix metalloproteinase-2 (MMP-2) positive inflammatory cells. Dz13 also improves cardiac function without influencing myocardial vascularity or fibrosis.

Conclusion— These findings demonstrate the regulatory role of c-Jun in the pathogenesis of myocardial inflammation and infarction following ischemia-reperfusion injury, and inhibition of this process using catalytic DNA.

Mechanism of recurrent ischemic mitral regurgitation after annuloplasty: continued LV remodeling as a moving target

BACKGROUND

Patients who undergo ring annuloplasty for ischemic mitral regurgitation (MR) often have persistent or recurrent MR. This may relate to persistent leaflet tethering from left ventricle (LV) dilatation that is not relieved by ring annuloplasty. Therefore, the purpose of this study was to test the hypothesis that recurrent MR in patients after ring annuloplasty relates to continued LV remodeling.

METHODS AND RESULTS

Serial echoes were reviewed in 30 patients (aged 72+/-11 years) who showed recurrent MR late (47+/-27 months) versus early (3.8+/-5.8 months) after ring annuloplasty for ischemic MR during coronary artery bypass grafting without interval infarction. Patients with intrinsic mitral valve disease were excluded. Echocardiographic measures of MR (vena contracta and jet area/left atrial area) and LV remodeling (LV dimensions, volumes, and sphericity) were assessed at each stage. The degree of MR increased from mild to moderate, on average, from early to late postoperative stages, without significant change in LV ejection fraction. Changes in MR paralleled increases in LV volumes and sphericity index at end-systole and end-diastole. The only independent predictor of late postoperative MR was LV sphericity index at end-systole.

CONCLUSIONS

Recurrent MR late after ring annuloplasty is associated with continued LV remodeling, emphasizing its dynamic relation to the LV.

Effect of ramipril and furosemide treatment on interstitial remodeling in post-infarction heart failure rat hearts

Extracellular matrix (ECM) remodeling and increased matrix metalloproteinase (MMP) expression and activity have been observed to be relevant in the development of heart failure (HF). We examined the effects of ramipril alone or with furosemide on ECM in a heart failure model. HF was induced by occlusion of the left coronary artery in spontaneously hypertensive rats (SHR). Rats were assigned to placebo (n=9), ramipril 1 mg/kg/day (n=11), furosemide 2 x 2 mg/kg/day (n=7) or both (1 mg/kg/day + 2 x 2 mg/kg/day n=8). LV-function, collagen content, MMP/TIMP (tissue inhibitor of matrix metalloproteinases) protein- and mRNA-expression were examined in non-infarcted LV tissue. MMP-2/TIMP-4 ratio was increased in HF. Ramipril reduced MMP-2 expression (active form), collagen type I mRNA expression and content and increased TIMP-4 levels associated with decreased left ventricular end diastolic pressure (LVEDP), mortality rate and increased LV pressure (LVP). Combination therapy with furosemide is less efficient with regard to collagen content and MMP-2 (active form) reduction but did not worsen beneficial effects of ramipril on LV function and mortality rate. Furosemide alone had no effect on MMP-2 (active form) expression, collagen content, LV function and mortality rate. Prevention of LV dilatation by ramipril was associated with decreased gelatinolytic activity and increased MMP-inhibition in heart failure SHR. Furthermore, ramipril reduced fibrosis by enhanced interstitial collagenase expression. Furosemide did not show the beneficial effects of ramipril on ECM remodeling but did not worsen LV function. Positive effects of furosemide treatment alone on LV remodeling and function were not observed.

Carvedilol in the treatment of chronic heart failure

Along with the angiotensin-converting enzyme inhibitors (ACEIs), the beta-adrenergic receptor blockers have gradually emerged to be standard in the therapy of heart failure. Individual beta-blockers that have been shown to reduce all-cause mortality in patients with heart failure include bisoprolol, metoprolol and carvedilol. Carvedilol distinguishes from the other beta-blockers as being a non-selective beta(1)- and beta(2)-receptor blocker with (1)-receptor blockade effect and anti-oxidant properties. The drug does not have sympathomimetic activity and has vasodilatory effects attributable to its (1)-receptor blockade property. Experimental and clinical studies have confirmed carvedilol's vasodilator, anti-oxidant and anti-apoptotic properties, which may contribute to its effect in reversing cardiac remodelling in animal models and patients with heart failure. These pharmacological properties render carvedilol a potentially useful agent in the treatment of patients with heart failure. Early studies of carvedilol in heart failure have reported beneficial haemodynamic effects but variable effects on exercise tolerance and clinical well being. The large-scale US Carvedilol Heart Failure Program and the Australian/New Zealand Heart Failure Collaborative Research Group reported beneficial effects of carvedilol on mortality, morbidity and clinical well being in patients with mild-to-moderate heart failure. The recently reported but yet unpublished preliminary results of the COPERNICUS study suggest that carvedilol improves mortality and morbidity in patients with advanced heart failure and severe symptoms. At this time, it is unclear whether the ancillary pharmacological properties of carvedilol can be translated to more superior clinical benefit compared to the other beta-blockers. Preliminary studies examining surrogate end points suggest that carvedilol may improve left ventricular ejection fraction (LVEF) more than metoprolol. More conclusive information regarding their relative effects of clinical outcomes will await the completion of the COMET study, which compares the effect of metoprolol and carvedilol on mortality and morbidity, expected at the end of the year 2002.

New and emerging pharmacological strategies in the management of chronic heart failure

Chronic heart failure is a complex syndrome involving the activation of multiple cellular, metabolic and neurohumoral pathways following the initial myocardial insult. Because of the complexity of the disease, strategies targeting these multiple systems involved in disease progression are required to maximise the therapeutic benefits of intervention. To this end, there are a number of approaches currently under active evaluation. These include the inhibition of additional neurohormonal vasoconstrictor systems (e.g. endothelin and vasopressin systems), cytokine antagonists (e.g. agents that block tumour necrosis factor-alpha activity), agents that favourably modulate extracellular matrix (e.g. matrix metalloprotease inhibitors) and agents that augment natriuretic peptides.

Angiotensin II induces nuclear factor- kappa B activation in cultured neonatal rat cardiomyocytes through protein kinase C signaling pathway

Rat neonatal ventricular cardiomyocytes (RNVM) possess G protein-coupled AT(1)receptors for angiotensin II (AngII) that activate multiple intracellular pathways. To elucidate potential signaling mechanisms involved, we focussed on the nuclear transcription factor-kappa B (NF- kappa B) in RNVM culture. Using specific antibody to NF- kappa Bp65, immunolocalization of NF- kappa B was cytoplasmic in unstimulated cardiomyocytes, whereas NF- kappa B was translocated into the RNVM nucleus in response to AngII. This translocation was inhibited in the presence of calphostin C, a specific inhibitor of protein kinase C (PKC). Western blot analysis showed an increase of NF- kappa B in AngII-stimulated cardiomyocyte nuclear extracts as compared to controls. Biomolecular interaction analysis (BIA analysis) of NF- kappa B activation showed that only AngII-nuclear extracts bound to NF- kappa B consensus sequence with a high degree of affinity. This DNA-binding capacity was completely lost in calphostin C-treated cells. At transcriptional level in RNVM, AngII mediates the upregulation of matrix gelatinase (MMP-9), which is totally inhibited by calphostin C treatment. In conclusion, cardiomyocyte nuclear NF- kappa B translocation in response to Ang II via PKC pathway activates cardiomyocyte-specific transcription of MMP-9 and may activate transcription from responsive genes which are involved in cardiac hypertrophy process and/or cardiac remodeling.

Altered balance between matrix gelatinases (MMP-2 and MMP-9) and their tissue inhibitors in human dilated cardiomyopathy: potential role of MMP-9 in myosin-heavy chain degradation

BACKGROUND

End-stage of human dilated cardiomyopathy (DCM) is characterized by myocyte loss and fibrosis, and associated with ventricular dilatation and reduced cardiac function. Matrix metalloproteinases (MMPs) and their natural tissue inhibitors (TIMPs) have been involved in the myocardial remodeling.

AIMS

To evaluate the potential role of matrix gelatinases (MMP-2 and MMP-9) in DCM, the balance between gelatinases and TIMPs and the gelatinase localization were investigated in left free wall ventricles from six normal donors and six patients with DCM at the transplantation time.

METHODS

TIMP-(1, 2, 3 and 4) mRNAs were analyzed by quantitative reverse transcription-polymerase chain reaction (RT-PCR). TIMP-1 and -2 protein content was assessed by ELISA. MMP-2 and MMP-9 expression were examined by zymography and immunological techniques.

RESULTS

All TIMPs were down-regulated in DCM hearts, especially TIMP-1 (reduced by 80%). Gel zymography revealed similar activity of MMP-2 and MMP-9 in both tissues. By in situ zymography and immunohistochemistry, active and immunoreactive gelatinases were pericardiomyocyte in control hearts and intracardiomyocyte in DCM hearts. Intracellular MMPs were associated with sarcomeric structure in DCM. To estimate a putative role of these gelatinases, several sarcomeric contractile proteins were digested in vitro by purified active MMP-9. Only myosin-heavy chain was cleaved in vitro giving 180-, 120-, 80- and 20-kDa proteolytic fragments. In vivo, two major myosin-heavy chain proteolytic fragments (80 and 20 kDa) were detected by specific monoclonal antibody against myosin-heavy chain in DCM left ventricular homogenates, only.

CONCLUSIONS

Taken together, these data highly suggest that MMP-2 and MMP-9 may be involved in the disorganization of the contractile apparatus in DCM hearts.