Effect of long-term monotherapy with the aldosterone receptor blocker eplerenone on cytoskeletal proteins and matrix metalloproteinases in dogs with heart failure.
ABSTRACT Long-term monotherapy with the aldosterone receptor blocker eplerenone in dogs with HF was previously shown to improve LV systolic and diastolic function. This study examined the effects of long-term monotherapy with the aldosterone receptor blocker eplerenone on mRNA and protein expression of the cytoskeletal proteins titin, tubulin, fibronectin and vimentin, the matrix metalloproteinases (MMPs)-1, -2 and -9, and the tissue inhibitors of MMPs (TIMPs)-1 and -2 in left ventricular (LV) myocardium of dogs with heart failure (HF).
HF was produced in 12 dogs by intracoronary microembolizations. Dogs were randomized to 3 months oral therapy with eplerenone (10 mg/kg twice daily, n = 6) or to no therapy at all (HF-control, n = 6). LV tissue from six normal dogs was used for comparison. mRNA expression was measured using reverse-transcriptase polymerase chain reaction (RT-PCR) and protein expression using Western blots.
Compared to NL dogs, control dogs showed upregulation of mRNA and protein expression for tubulin, fibronectin, MMP-1, -2 and -9, and down-regulation of mRNA and protein expression for total titin. Normalization of mRNA and protein expression for all these genes was seen after treatment with eplerenone. N2BA/N2B-titin mRNA expression ratio increased significantly in dogs with HF treated with eplerenone. No differences in expression for vimentin, TIMP-1 and -2 were observed among groups.
In dogs with HF, long-term eplerenone therapy normalizes mRNA and protein expression of key cytoskeletal proteins and MMPs. Reversal of these molecular maladaptations may partly explain the improvement in LV diastolic function seen after long-term therapy with eplerenone.
SourceAvailable from: Rugmani Iyer[Show abstract] [Hide abstract]
ABSTRACT: Matrix metalloproteinase (MMP)-9, one of the most widely investigated MMPs, regulates pathological remodeling processes that involve inflammation and fibrosis in cardiovascular disease. MMP-9 directly degrades extracellular matrix (ECM) proteins and activates cytokines and chemokines to regulate tissue remodeling. MMP-9 deletion or inhibition has proven overall beneficial in multiple animal models of cardiovascular disease. As such, MMP-9 expression and activity is a common end point measured. MMP-9 cell-specific overexpression, however, has also proven beneficial and highlights the fact that little information is available on the underlying mechanisms of MMP-9 function. In this review, we summarize our current understanding of MMP-9 physiology, including structure, regulation, activation, and downstream effects of increased MMP-9. We discuss MMP-9 roles during inflammation and fibrosis in cardiovascular disease. By concentrating on the substrates of MMP-9 and their roles in cardiovascular disease, we explore the overall function and discuss future directions on the translational potential of MMP-9 based therapies.Physiology 11/2013; 28(6):391-403. DOI:10.1152/physiol.00029.2013 · 5.65 Impact Factor
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ABSTRACT: IntroductionMineralocorticoid receptor antagonism reduces sudden cardiac death in heart failure, but the underlying mechanism remains poorly understood. Concurrent treatment with a mineralocorticoid receptor antagonist during rapid ventricular pacing prevents development of adverse ventricular electrophysiological remodeling, interstitial fibrosis, inflammatory cytokine gene activation and ventricular tachyarrhythmia inducibility without diminishing the extent of systolic dysfunction. We hypothesized that attenuating preexistent inflammatory pathways and myocardial fibrosis with eplerenone after systolic heart failure is established by rapid pacing can reduce electrical activation delays and arrhythmia vulnerability. Methods and ResultsDogs subjected to rapid ventricular pacing for 8 weeks in the absence or presence of eplerenone treatment during the final 4 weeks of pacing were assessed by echocardiography, electrophysiology study, ventricular fibrosis measurements and inflammatory cytokine mRNA expression analysis. Eplerenone reversed preexistent ventricular activation delays, interstitial fibrosis, inflammatory cytokine (interleukin-6, tumor necrosis factor-α) gene overexpression and arrhythmia vulnerability in ventricular paced dogs with heart failure. Eplerenone failed to improve LV systolic dysfunction or chamber enlargement. A correlation between severity of fibrosis and ventricular arrhythmia inducibility was found. Conclusions Mineralocorticoid receptor antagonism regresses rapid pacing-induced electrical delays, inflammatory cytokine gene activation and fibrosis in heart failure. Ventricular arrhythmia vulnerability in heart failure is correlated with extent of fibrosis and electrical activation delays during premature excitation.This article is protected by copyright. All rights reserved.Journal of Cardiovascular Electrophysiology 02/2014; 25(5). DOI:10.1111/jce.12379 · 2.88 Impact Factor
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ABSTRACT: The aim of this study was to determine the influence of high glucose (HG) and interleukin (IL)-1β on human cardiac fibroblast (HCF) functions, and to evaluate the effects of eplerenone in these responses. HCFs were cultured in normal or HG media in the absence or presence of IL-1β and/or eplerenone. We assessed matrix metalloproteinase-2 (MMP-2) activity in the supernatant by in-gel zymography, and determined mRNA expression levels of MMP-2 and tissue inhibitor of metalloproteinase-2 (TIMP-2) by reverse transcription-polymerase chain reaction. Equimolar D-mannitol was used as an osmotic control. HG stimulated MMP-2 activity and promoted MMP-2 mRNA synthesis. Increased effects were also observed in equimolar D-mannitol treatments, but these effects were weaker compared to those of glucose. The combination of HG and IL-1β resulted in a two-fold increase in MMP-2 activity and mRNA expression compared with HG or IL-1β alone. Increases in HG- or IL-1β-induced MMP-2 activity and mRNA expression were blocked by eplerenone. Neither HG nor IL-1β affected TIMP- 2 mRNA expression. HG increased MMP-2 activity by regulation of MMP-2 mRNA expression in HFCs through osmotic and non-osmotic pathways. Synergistic effects of IL-1β added to HG media on MMP-2 activity and mRNA expression were observed in HCFs. Eplerenone normalized the effect of MMP-2 activity and HG- or IL-1β-induced expression in HCFs.Genetics and molecular research: GMR 01/2014; 13(AOP). DOI:10.4238/2014.January.24.4 · 0.85 Impact Factor