Inflammation and postinfarct remodeling: Overexpression of IκB prevents ventricular dilation via increasing TIMP levels
TL;DR: Reducing NF-kappaB activity via IkappaB overexpression after MI positively influences ECM remodeling by reducing MMP-2 and -9 levels while increasing TIMP-1, -2, -3, and -4 levels.
Abstract: Objective: Nuclear factor-kappa B (NF-κB) orchestrates genes involved in inflammation and extracellular matrix (ECM) remodeling following myocardial infarction (MI). The objective of the present study was to investigate the effect of overexpression and mode of function of IκB, the natural inhibitor of NF-κB, on ECM remodeling in a rat model of MI.
Methods: MI was induced in male Sprague-Dawley rats by ligation of the left anterior descending coronary artery (LAD) and was followed by adenovirus-mediated intramyocardial transfection of IκB ( n =26) or LacZ reporter genes ( n =26). Sham-operated animals ( n =14) served as controls.
Results: In transthoracic echocardiography 49 days after MI, systolic and diastolic left ventricular dimensions were reduced while fractional shortening was preserved in the treatment group. Additionally, evaluation on the isolated heart showed an attenuated downward shift of pressure–volume relationships in the IκB group compared to LacZ. NF-κB p65 DNA binding activity was diminished both at 5 and 49 days post-MI in the treatment group. Five days post-MI in the treatment group, protein levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1β were significantly reduced by 72.6% and 73.2%, respectively, compared to LacZ ( p <0.05). In parallel, matrix metalloproteinase (MMP)-2 and MMP-9 levels were reduced 5 days post-MI, with MMP-9 still being decreased 49 days post-MI ( p <0.01). In contrast, tissue inhibitors of metalloproteinases (TIMP)-1, -2, and -3 were increased compared to LacZ ( p <0.01 and p <0.05, respectively) 5 days post-MI. After 49 days, TIMP-2, -3, and -4 expressions were significantly elevated ( p <0.05).
Conclusion: Reducing NF-κB activity via IκB overexpression after MI positively influences ECM remodeling by reducing MMP-2 and -9 levels while increasing TIMP-1, -2, -3, and -4 levels. Therefore, IκB overexpression prevents ventricular dilation and consequently preserves cardiac function.
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TL;DR: The renin-angiotensin-aldosterone system and members of the transforming growth factor-β family play an important role in activation of infarct myofibroblasts, and therapeutic modulation of the inflammatory and reparative response may hold promise for the prevention of postinfarction heart failure.
Abstract: In adult mammals, massive sudden loss of cardiomyocytes after infarction overwhelms the limited regenerative capacity of the myocardium, resulting in the formation of a collagen-based scar. Necrotic cells release danger signals, activating innate immune pathways and triggering an intense inflammatory response. Stimulation of toll-like receptor signaling and complement activation induces expression of proinflammatory cytokines (such as interleukin-1 and tumor necrosis factor-α) and chemokines (such as monocyte chemoattractant protein-1/ chemokine (C-C motif) ligand 2 [CCL2]). Inflammatory signals promote adhesive interactions between leukocytes and endothelial cells, leading to extravasation of neutrophils and monocytes. As infiltrating leukocytes clear the infarct from dead cells, mediators repressing inflammation are released, and anti-inflammatory mononuclear cell subsets predominate. Suppression of the inflammatory response is associated with activation of reparative cells. Fibroblasts proliferate, undergo myofibroblast transdifferentiation, and deposit large amounts of extracellular matrix proteins maintaining the structural integrity of the infarcted ventricle. The renin–angiotensin–aldosterone system and members of the transforming growth factor-β family play an important role in activation of infarct myofibroblasts. Maturation of the scar follows, as a network of cross-linked collagenous matrix is formed and granulation tissue cells become apoptotic. This review discusses the cellular effectors and molecular signals regulating the inflammatory and reparative response after myocardial infarction. Dysregulation of immune pathways, impaired suppression of postinfarction inflammation, perturbed spatial containment of the inflammatory response, and overactive fibrosis may cause adverse remodeling in patients with infarction contributing to the pathogenesis of heart failure. Therapeutic modulation of the inflammatory and reparative response may hold promise for the prevention of postinfarction heart failure.
1,266 citations
TL;DR: Roles of peroxynitrite in the redox regulation of key signalling pathways for cardiovascular homeostasis, including protein kinase B and C, the MAP kinases, Nuclear Factor Kappa B, as well as signalling dependent on insulin and the sympatho-adrenergic system are presented in detail in this review.
Abstract: Peroxynitrite is a potent oxidant and nitrating species formed from the reaction between the free radicals nitric oxide and superoxide. An excessive formation of peroxynitrite represents an important mechanism contributing to cell death and dysfunction in multiple cardiovascular pathologies, such as myocardial infarction, heart failure and atherosclerosis. Whereas initial works focused on direct oxidative biomolecular damage as the main route of peroxynitrite toxicity, more recent evidence, mainly obtained in vitro, indicates that peroxynitrite also behaves as a potent modulator of various cell signal transduction pathways. Due to its ability to nitrate tyrosine residues, peroxynitrite affects cellular processes dependent on tyrosine phosphorylation. Peroxynitrite also exerts complex effects on the activity of various kinases and phosphatases, resulting in the up- or downregulation of signalling cascades, in a concentration- and cell-dependent manner. Such roles of peroxynitrite in the redox regulation of key signalling pathways for cardiovascular homeostasis, including protein kinase B and C, the MAP kinases, Nuclear Factor Kappa B, as well as signalling dependent on insulin and the sympatho-adrenergic system are presented in detail in this review.
193 citations
Cites result from "Inflammation and postinfarct remode..."
...Comparable results have been obtained using a strategy of myocardial overexpression of IkappaBalpha by adenovirusmediated transfection in rats (107)....
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TL;DR: The studies demonstrate that TNF-alpha-induced oxidative stress alters redox homeostasis by impairing the MPTP proteins adenine nucleotide translocator and voltage-dependent anion channel, thereby resulting in the pore opening, causing uncontrolled transport of substances to alter mitochondrial pH, and subsequently leading to dysfunction of mitochondria and attenuated cardiac function.
Abstract: Mitochondria are indispensable for bioenergetics and for the regulation of physiological/signaling events in cellular life. Although TNF-α-induced oxidative stress and mitochondrial dysfunction are...
163 citations
TL;DR: Treatment with recombinant osteopontin prevented a significant loss in body weight, neurologic impairment, brain edema, and blood–brain barrier disruption after subarachnoid hemorrhage.
Abstract: Objective
Accumulated evidence suggests that the primary cause of poor outcome after subarachnoid hemorrhage (SAH) is not only cerebral arterial narrowing, but also early brain injury (EBI). Our objective was to determine the effect of recombinant osteopontin (r-OPN), a pleiotropic extracellular matrix glycoprotein, on post-SAH EBI in rats.
104 citations
TL;DR: Clinical, genetic and experimental approaches employed to compare ECM, MMP and TIMP profiles in healthy, compensated and failing hearts are reviewed and common themes in the perturbation of ECM homeostasis in the transition to heart failure are identified.
Abstract: The myocardial extracellular matrix (ECM), which preserves the geometry and integrity of the myocardium, is a dynamic structure whose component proteins are maintained by a finely controlled homeostatic balance between deposition and degradation. One of the key targets in cardiology is the elucidation of the molecular mechanisms which mediate pathological remodelling of this matrix causing the transition from compensatory hypertrophy to congestive decompensated heart failure. In response to injury or increased workload, cardiac remodelling including myocyte hypertrophy, develops as the heart attempts to compensate for increased wall stresses. Persistence of these stresses over extended time periods leads to disruption of ECM homeostasis resulting in irreversible maladaptive cardiac remodelling, ventricular dilatation and finally heart failure. ECM remodelling is regulated by the matrix metalloproteinases (MMPs) and their endogenous inhibitors (TIMPs). Clinical studies and experimental models of cardiac disease states have reported alterations in the balance between the MMPs and TIMPs in the failing heart and crucially at intermediate time points in the progression to failure. This article reviews the recent clinical, genetic and experimental approaches employed to compare ECM, MMP and TIMP profiles in healthy, compensated and failing hearts and identifies common themes in the perturbation of ECM homeostasis in the transition to heart failure.
102 citations
Cites background from "Inflammation and postinfarct remode..."
...…of this, limited left ventricular dilation and reduced expression of MMP-2 and MMP-9 was observed in rats overexpressing the endogenous inhibitor (IjB) of the NF-jB transcription factor (which regulates MMP-2 and 9 gene transcription) following coronary artery ligation (Trescher et al. 2006)....
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References
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TL;DR: Temporary administration of PA inhibitor-1 or the matrix metalloproteinase-inhibitor TIMP-1 completely protected wild-type mice against rupture but did not abort infarct healing, thus constituting a new approach to prevent cardiac rupture after acute myocardial infarction.
Abstract: Cardiac rupture is a fatal complication of acute myocardial infarction lacking treatment. Here, acute myocardial infarction resulted in rupture in wild-type mice and in mice lacking tissue-type plasminogen activator, urokinase receptor, matrix metalloproteinase stromelysin-1 or metalloelastase. Instead, deficiency of urokinase-type plasminogen activator (u-PA–/–) completely protected against rupture, whereas lack of gelatinase-B partially protected against rupture. However, u-PA–/– mice showed impaired scar formation and infarct revascularization, even after treatment with vascular endothelial growth factor, and died of cardiac failure due to depressed contractility, arrhythmias and ischemia. Temporary administration of PA inhibitor-1 or the matrix metalloproteinase-inhibitor TIMP-1 completely protected wild-type mice against rupture but did not abort infarct healing, thus constituting a new approach to prevent cardiac rupture after acute myocardial infarction.
815 citations
"Inflammation and postinfarct remode..." refers result in this paper
...In contrast, other studies reported an impairment of the normal wound-healing response with deleterious effects on myocardial function due to the loss of MMP-activity in the acute phase post-MI [32,33]....
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TL;DR: It is concluded that targeted deletion of the MMP9 gene attenuates LV dilation after experimental MI in mice and the decrease in collagen accumulation and the enhanced expression of other MMPs suggest that MMP-9 plays a prominent role in extracellular matrix remodeling after MI.
Abstract: Matrix metalloproteinase-9 (MMP-9) is prominently overexpressed after myocardial infarction (MI). We tested the hypothesis that mice with targeted deletion of MMP9 have less left ventricular (LV) dilation after experimental MI than do sibling wild-type (WT) mice. Animals that survived ligation of the left coronary artery underwent echocardiographic studies after MI; all analyses were performed without knowledge of mouse genotype. By day 8, MMP9 knockout (KO) mice had significantly smaller increases in end-diastolic and end-systolic ventricular dimensions at both midpapillary and apical levels, compared with infarcted WT mice; these differences persisted at 15 days after MI. MMP-9 KO mice had less collagen accumulation in the infarcted area than did WT mice, and they showed enhanced expression of MMP-2, MMP-13, and TIMP-1 and a reduced number of macrophages. We conclude that targeted deletion of the MMP9 gene attenuates LV dilation after experimental MI in mice. The decrease in collagen accumulation and the enhanced expression of other MMPs suggest that MMP-9 plays a prominent role in extracellular matrix remodeling after MI.
786 citations
"Inflammation and postinfarct remode..." refers result in this paper
...Similar results concerning LV remodeling could be achieved in MMP-9-deficient mice after MI [31]....
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TL;DR: Efficient, long-term in vivo gene transfer throughout mouse skeletal and cardiac muscles after intravenous administration of a recombinant adenovirus raises the possibility that muscular degenerative diseases might one day be treatable by gene therapy.
Abstract: Successful treatment of muscular disorders awaits an adapted gene delivery protocol. The clinically applicable technique used for hematopoietic cells which is centered around implantation of retrovirally modified cells may not prove sufficient for a reversal of phenotype when muscle diseases are concerned. We report here efficient, long-term in vivo gene transfer throughout mouse skeletal and cardiac muscles after intravenous administration of a recombinant adenovirus. This simple, direct procedure raises the possibility that muscular degenerative diseases might one day be treatable by gene therapy.
737 citations
TL;DR: The biology of MMPs is described and the central role of the plasminogen system as an important activator of M MPs in the remodeling process after myocardial infarction is speculated on.
Abstract: Increased activity of matrix metalloproteinases (MMPs) has been implicated in numerous disease processes, including tumor growth and metastasis, arthritis, and periodontal disease. It is now becoming increasingly clear that extracellular matrix degradation by MMPs is also involved in the pathogenesis of cardiovascular disease, including atherosclerosis, restenosis, dilated cardiomyopathy, and myocardial infarction. Administration of synthetic MMP inhibitors in experimental animal models of these cardiovascular diseases significantly inhibits the progression of, respectively, atherosclerotic lesion formation, neointima formation, left ventricular remodeling, pump dysfunction, and infarct healing. This review focuses on the role of MMPs in cardiovascular disease, in particular myocardial infarction and the subsequent progression to heart failure. MMPs, which are present in the myocardium and capable of degrading all the matrix components of the heart, are the driving force behind myocardial matrix remodeling. The recent finding that acute pharmacological inhibition of MMPs or deficiency in MMP-9 attenuates left ventricular dilatation in the infarcted mouse heart led to the proposal that MMP inhibitors could be used as a potential therapy for patients at risk for the development of heart failure after myocardial infarction. Although these promising results encourage the design of clinical trials with MMP inhibitors, there are still several unresolved issues. This review describes the biology of MMPs and discusses new insights into the role of MMPs in several cardiovascular diseases. Attention will be paid to the central role of the plasminogen system as an important activator of MMPs in the remodeling process after myocardial infarction. Finally, we speculate on the use of MMP inhibitors as potential therapy for heart failure.
640 citations
"Inflammation and postinfarct remode..." refers background in this paper
...A hallmark of early CR post-MI is the expansion of the infarcted area as a result of the degradation of ECM molecules, caused by an imbalance in the ratio of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) [4]....
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TL;DR: The first successful in vivo transfer of NFκB decoy oligodeoxynucleotides to reduce the extent of myocardial infarction following reperfusion is reported, providing a new therapeutic strategy for myocardia infarctions.
Abstract: The transcriptional factor nuclear factor-kappaB (NFkappaB) plays a pivotal role in the coordinated transactivation of cytokine and adhesion molecule genes that might be involved in myocardial damage after ischemia and reperfusion. Therefore, we hypothesized that synthetic double-stranded DNA with high affinity for NFkappaB could be introduced in vivo as "decoy" cis elements to bind the transcriptional factor and to block the activation of genes mediating myocardial infarction, thus providing effective therapy for myocardial infarction. Treatment before and after infarction by transfection of NFkappaB decoy, but not scrambled decoy, oligodeoxynucleotides before coronary artery occlusion or immediately after reperfusion had a significant inhibitory effect on the area of infarction. Here, we report the first successful in vivo transfer of NFkappaB decoy oligodeoxynucleotides to reduce the extent of myocardial infarction following reperfusion, providing a new therapeutic strategy for myocardial infarction.
621 citations
"Inflammation and postinfarct remode..." refers methods in this paper
...In an experimental model of MI in rats similar to ours, Morishita et al. used NF-nB cis element decoys to reduce NF-nB activation and observed an attenuation of the inflammatory response from 2 up to 48 h post-MI [ 13 ]....
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