Mitochondrial Sirtuin-3 (SIRT3) Prevents Doxorubicin-Induced Dilated Cardiomyopathy by Modulating Protein Acetylation and Oxidative Stress.

BACKGROUND: High doses of doxorubicin put cancer patients at risk for developing dilated cardiomyopathy. Previously, we showed that doxorubicin treatment decreases SIRT3 (sirtuin 3), the main mitochondrial deacetylase and increases protein acetylation in rat cardiomyocytes. Here, we hypothesize that SIRT3 expression can attenuate doxorubicin induced dilated cardiomyopathy in vivo by preventing the acetylation of mitochondrial proteins. METHODS: Nontransgenic, M3-SIRT3 (truncated SIRT3; short isoform), and M1-SIRT3 (full-length SIRT3; mitochondrial localized) transgenic mice were treated with doxorubicin for 4 weeks (8 mg/kg body weight per week). Echocardiography was performed to assess cardiac structure and function and validated by immunohistochemistry and immunofluorescence (n=4-10). Mass spectrometry was performed on cardiac mitochondrial peptides in saline (n=6) and doxorubicin (n=5) treated hearts. Validation was performed in doxorubicin treated primary rat and human induced stem cell derived cardiomyocytes transduced with adenoviruses for M3-SIRT3 and M1-SIRT3 and deacetylase deficient mutants (n=4-10). RESULTS: Echocardiography revealed that M3-SIRT3 transgenic mice were partially resistant to doxorubicin induced changes to cardiac structure and function whereas M1-SIRT3 expression prevented cardiac remodeling and dysfunction. In doxorubicin hearts, 37 unique acetylation sites on mitochondrial proteins were altered. Pathway analysis revealed these proteins are involved in energy production, fatty acid metabolism, and oxidative stress resistance. Increased M1-SIRT3 expression in primary rat and human cardiomyocytes attenuated doxorubicin-induced superoxide formation, whereas deacetylase deficient mutants were unable to prevent oxidative stress. CONCLUSIONS: Doxorubicin reduced SIRT3 expression and markedly affected the cardiac mitochondrial acetylome. Increased M1-SIRT3 expression in vivo prevented doxorubicin-induced cardiac dysfunction, suggesting that SIRT3 could be a potential therapeutic target for mitigating doxorubicin-induced dilated cardiomyopathy.

Oridonin enhances antitumor effects of doxorubicin in human osteosarcoma cells.

BACKGROUND: Doxorubicin is the chemotherapeutic drug of choice in osteosarcoma treatment, but its cumulative administration causes dilated cardiomyopathy. Combination therapy represents a potential strategy to reduce the therapeutic dosage of the chemotherapeutic agent and minimize its side effects. The aim of this study was to evaluate the potential of oridonin, a natural product from the medicinal herb Rabdosia rubescens, to act in combination with doxorubicin for osteosarcoma treatment. To date, there are no reports of the simultaneous administration of both drugs in osteosarcoma therapy. METHODS: The combined administration of different doses of oridonin and doxorubicin, as compared with the drugs alone, were tested in an in vitro model of osteosarcoma. The synergistic effect of the drugs on cell death was assessed by alamarBlue™ and by CompuSyn software. Early and late apoptosis markers (JC-1 fluorescence and Annexin V immunofluorescence), as well as the production of reactive oxygen species, were evaluated by flow cytometry. Western blot was used to assess the expression of anti-apoptotic proteins. RESULTS: Oridonin and doxorubicin presented a synergistic cytotoxic effect in osteosarcoma cells. In the presence of sub-cytotoxic concentrations of the natural product, there was an increased accumulation of intracellular doxorubicin, increased levels of reactive oxygen species (ROS), alteration of mitochondria membrane potential and a higher rate of apoptosis. CONCLUSION: The combined use of oridonin and doxorubicin could help to reduce the clinical dosage of doxorubicin and its dangerous side effects.

Exercise Training Improved Pulmonary Gas Exchange Abnormalities in Pulmonary Hypertension due to Heart Failure: A Case Report

Abstract Heart failure (HF) is the most common cause of pulmonary hypertension (PH), and reduced exercise capacity and exertional dyspnea are the most frequent concerns in patients with PH-HF. Indeed, carbon dioxide end-tidal partial pressure (PETCO 2 ) during exercise is a well-established noninvasive marker of ventilation/perfusion ratio in PH. We aimed to evaluate the effect of aerobic exercise training on PETCO 2 response during exercise in a 59-year-old woman with PH secondary to idiopathic dilated cardiomyopathy. The patient with chronic fatigue and dyspnea at mild-to-moderate efforts was admitted to a cardiorespiratory rehabilitation program and had her cardiorespiratory response to exercise assessed during a cardiopulmonary exercise testing performed before and after three months of a thrice-weekly aerobic exercise training program. Improvements in aerobic capacity (23.9%) and endurance time (37.5%) and reduction in ventilatory inefficiency (-20.2%) was found after intervention. Post-intervention improvements in PETCO 2 at ventilatory anaerobic threshold (23.3%) and change in PETCO 2 kinetics pattern, with progressive increases from rest to peak of exercise, were also found. Patient also improved breathing pattern and timing of ventilation. This case report demonstrated for the first time that aerobic exercise training might be able to improve PETCO 2 response during exercise in a patient with PH-HF.

LncRNA AC061961.2 overexpression inhibited endoplasmic reticulum stress induced apoptosis in dilated cardiomyopathy rats and cardiomyocytes via activating wnt/ß-catenin pathway.

Down-regulated lncRNA AC061961.2 in dilated cardiomyopathy (DCM) patients was previous reported. Whether AC061961.2 has regulatory effect on DCM still need exploration. Here, we tried to investigate the effect of AC061961.2 on DCM. After DCM model rat was established through injecting Adriamycin, left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD), left ventricular ejection fraction (LVEF), and left ventricular fractional shortening (LVFS) were measured by echocardiography. Histopathological changes and apoptosis were detected by hematoxylin-eosin, Masson staining, and TUNEL. After cardiomyocytes were isolated and identified by immunofluorescence, DCM cell model was established by injecting adriamycin. After transfected with overexpressed-AC061961.2 plasmids, cell apoptosis was detected by flow cytometry. The expressions of AC061961.2, ß-catenin, Axin2, c-Myc, CRP78, CHOP, Caspase-3, Bcl-2, and Bax in cardiomyocytes and heart tissues were detected by RT-qPCR or western blot. LVEDD and LVESD were increased while LVEF and LVFS were decreased in DCM rats. The histopathological of heart tissues showed a typical sign of DCM. Apoptosis were increased in heart tissues of DCM rats. In DCM rats, the expressions of AC061961.2, ß-catenin, Axin2, c-Myc, and Bcl-2 were decreased, the expressions of CRP78, CHOP, Caspase-3, and Bax were increased. After the overexpression of AC061961.2, levels of ß-catenin, Axin2, c-Myc, and Bcl-2 were increased, while levels of CRP78, CHOP, Caspase-3, and Bax were decreased, compared with that in DCM cardiomyocytes. LncRNA AC061961.2 overexpression inhibited endoplasmic reticulum stress induced apoptosis in DCM rats and cardiomyocytes via activating Wnt/ß-catenin pathway.

Self-Maintenance of Cardiac Resident Reparative Macrophages Attenuates Doxorubicin-Induced Cardiomyopathy Through the SR-A1-c-Myc Axis.

RATIONALE: Doxorubicin-induced cardiomyopathy (DiCM) is a primary cause of heart failure and mortality in cancer patients, in which macrophage-orchestrated inflammation serves as an essential pathological mechanism. However, the specific roles of tissue-resident and monocyte-derived macrophages in DiCM remain poorly understood. OBJECTIVE: Uncovering the origins, phenotypes, and functions of proliferative cardiac resident macrophages and mechanistic insights into the self-maintenance of cardiac macrophage during DiCM progression. METHODS AND RESULTS: Mice were administrated with doxorubicin to induce cardiomyopathy. Dynamic changes of resident and monocyte-derived macrophages were examined by lineage tracing, parabiosis, and bone marrow transplantation. We found that the monocyte-derived macrophages primarily exhibited a proinflammatory phenotype that dominated the whole DiCM pathological process and impaired cardiac function. In contrast, cardiac resident macrophages were vulnerable to doxorubicin insult. The survived resident macrophages exhibited enhanced proliferation and conferred a reparative role. Global or myeloid specifically ablation of SR-A1 (class A1 scavenger receptor) inhibited proliferation of cardiac resident reparative macrophages and, therefore, exacerbated cardiomyopathy in DiCM mice. Importantly, the detrimental effect of macrophage SR-A1 deficiency was confirmed by transplantation of bone marrow. At the mechanistic level, we show that c-Myc (Avian myelocytomatosis virus oncogene cellular homolog), a key transcriptional factor for the SR-A1-P38-SIRT1 (Sirtuin 1) pathway, mediated the effect of SR-A1 in reparative macrophage proliferation in DiCM. CONCLUSIONS: The SR-A1-c-Myc axis may represent a promising target to treat DiCM through augmentation of cardiac resident reparative macrophage proliferation.

Cardioprotective effects of α-cardiac actin on oxidative stress in a dilated cardiomyopathy mouse model.

The expression of α-cardiac actin, a major constituent of the cytoskeleton of cardiomyocytes, is dramatically decreased in a mouse model of dilated cardiomyopathy triggered by inducible cardiac-specific serum response factor (Srf) gene disruption that could mimic some forms of human dilated cardiomyopathy. To investigate the consequences of the maintenance of α-cardiac actin expression in this model, we developed a new transgenic mouse based on Cre/LoxP strategy, allowing together the induction of SRF loss and a compensatory expression of α-cardiac actin. Here, we report that maintenance of α-cardiac actin within cardiomyocytes temporally preserved cytoarchitecture from adverse cardiac remodeling through a positive impact on both structural and transcriptional levels. These protective effects were accompanied in vivo by the decrease of ROS generation and protein carbonylation and the downregulation of NADPH oxidases NOX2 and NOX4. We also show that ectopic expression of α-cardiac actin protects HEK293 cells against oxidative stress induced by H2 O2 . Oxidative stress plays an important role in the development of cardiac remodeling and contributes also to the pathogenesis of heart failure. Taken together, these findings indicate that α-cardiac actin could be involved in the regulation of oxidative stress that is a leading cause of adverse remodeling during dilated cardiomyopathy development.

Cardiac Protection after Systemic Transplant of Dystrophin Expressing Chimeric (DEC) Cells to the mdx Mouse Model of Duchenne Muscular Dystrophy.

Duchenne Muscular Dystrophy (DMD) is a progressive lethal disease caused by X-linked mutations of the dystrophin gene. Dystrophin deficiency clinically manifests as skeletal and cardiac muscle weakness, leading to muscle wasting and premature death due to cardiac and respiratory failure. Currently, no cure exists. Since heart disease is becoming a leading cause of death in DMD patients, there is an urgent need to develop new more effective therapeutic strategies for protection and improvement of cardiac function. We previously reported functional improvements correlating with dystrophin restoration following transplantation of Dystrophin Expressing Chimeric Cells (DEC) of myoblast origin in the mdx and mdx/scid mouse models. Here, we confirm positive effect of DEC of myoblast (MBwt/MBmdx) and mesenchymal stem cells (MBwt/MSCmdx) origin on protection of cardiac function after systemic DEC transplant. Therapeutic effect of DEC transplant (0.5 × 106) was assessed by echocardiography at 30 and 90 days after systemic-intraosseous injection to the mdx mice. At 90 days post-transplant, dystrophin expression in cardiac muscles of DEC injected mice significantly increased (15.73% ± 5.70 -MBwt/MBmdx and 5.22% ± 1.10 - MBwt/MSCmdx DEC) when compared to vehicle injected controls (2.01% ± 1.36) and, correlated with improved ejection fraction and fractional shortening on echocardiography. DEC lines of MB and MSC origin introduce a new promising approach based on the combined effects of normal myoblasts with dystrophin delivery capacities and MSC with immunomodulatory properties. Our study confirms feasibility and efficacy of DEC therapy on cardiac function and represents a novel therapeutic strategy for cardiac protection and muscle regeneration in DMD.

Inhibition of the Hypoxia-Inducible Factor 1α-Induced Cardiospecific HERNA1 Enhance-Templated RNA Protects From Heart Disease.

BACKGROUND: Enhancers are genomic regulatory elements conferring spatiotemporal and signal-dependent control of gene expression. Recent evidence suggests that enhancers can generate noncoding enhancer RNAs, but their (patho)biological functions remain largely elusive. METHODS: We performed chromatin immunoprecipitation-coupled sequencing of histone marks combined with RNA sequencing of left ventricular biopsies from experimental and genetic mouse models of human cardiac hypertrophy to identify transcripts revealing enhancer localization, conservation with the human genome, and hypoxia-inducible factor 1α dependence. The most promising candidate, hypoxia-inducible enhancer RNA ( HERNA)1, was further examined by investigating its capacity to modulate neighboring coding gene expression by binding to their gene promoters by using chromatin isolation by RNA purification and λN-BoxB tethering-based reporter assays. The role of HERNA1 and its neighboring genes for pathological stress-induced growth and contractile dysfunction, and the therapeutic potential of HERNA1 inhibition was studied in gapmer-mediated loss-of-function studies in vitro using human induced pluripotent stem cell-derived cardiomyocytes and various in vivo models of human pathological cardiac hypertrophy. RESULTS: HERNA1 is robustly induced on pathological stress. Production of HERNA1 is initiated by direct hypoxia-inducible factor 1α binding to a hypoxia-response element in the histoneH3-lysine27acetylation marks-enriched promoter of the enhancer and confers hypoxia responsiveness to nearby genes including synaptotagmin XVII, a member of the family of membrane-trafficking and Ca2+-sensing proteins and SMG1, encoding a phosphatidylinositol 3-kinase-related kinase. Consequently, a substrate of SMG1, ATP-dependent RNA helicase upframeshift 1, is hyperphoshorylated in a HERNA1- and SMG1-dependent manner. In vitro and in vivo inactivation of SMG1 and SYT17 revealed overlapping and distinct roles in modulating cardiac hypertrophy. Finally, in vivo administration of antisense oligonucleotides targeting HERNA1 protected mice from stress-induced pathological hypertrophy. The inhibition of HERNA1 postdisease development reversed left ventricular growth and dysfunction, resulting in increased overall survival. CONCLUSIONS: HERNA1 is a novel heart-specific noncoding RNA with key regulatory functions in modulating the growth, metabolic, and contractile gene program in disease, and reveals a molecular target amenable to therapeutic exploitation.

(-)-Epicatechin inhibits development of dilated cardiomyopathy in δ sarcoglycan null mouse.

BACKGROUND AND AIMS: Several studies propose that (-)-epicatechin, a flavonol present in high concentration in the cocoa, has cardioprotective effects. This study aimed to evaluate the impact of (-)-epicatechin on the development of dilated cardiomyopathy in a δ sarcoglycan null mouse model. METHODS AND RESULTS: δ Sarcoglycan null mice were treated for 15 days with (-)-epicatechin. Histological and morphometric analysis of the hearts treated mutant mice showed significant reduction of the vasoconstrictions in the coronary arteries as well as fewer areas with fibrosis and a reduction in the loss of the ventricular wall. On the contrary, it was observed a thickening of this region. By Western blot analysis, it was shown, and increment in the phosphorylation level of eNOS and PI3K/AKT/mTOR/p70S6K proteins in the heart of the (-)-epicatechin treated animals. On the other hand, we observed a significantly decreased level of the atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) heart failure markers. CONCLUSION: All the results indicate that (-)-epicatechin has the potential to prevent the development of dilated cardiomyopathy of genetic origin and encourages the use of this flavonol as a pharmacological therapy for dilated cardiomyopathy and heart failure diseases.

FasL expression in cardiomyocytes activates the ERK1/2 pathway, leading to dilated cardiomyopathy and advanced heart failure.

Increase in the apoptotic molecule Fas ligand (FasL) in serum and cardiomyocytes has been shown to be associated with progressive dilated cardiomyopathy (DCM) and congestive heart failure (CHF) in humans. However, the underlying mechanism(s) of FasL-related deterioration of heart function remain obscure. The aim of the present study is to determine roles of myocardial FasL in the activation of alternative pathways such as extracellular-signal-regulated kinase 1/2 (ERK1/2), inflammation or fibrosis and to identify effective treatments of progressive DCM and advanced CHF. Transgenic mice with cardiomyocyte-specific overexpression of FasL were investigated and treated with an ERK1/2 inhibitor (U-0126), losartan (los), prednisolone (pred) or placebo. Morpho-histological and molecular studies were subsequently performed. FasL mice showed significantly higher mortality compared with wild-type (WT) littermates due to DCM and advanced CHF. Prominent perivascular and interstitial fibrosis, increased interleukin secretion and diffuse CD3-positive cell infiltration were evident in FasL hearts. Up-regulation of the short form of Fas-associated death domain (FADD)-like interleukin 1ß-converting enzyme (FLICE) inhibitory protein (s-FLIP), RIP (receptor-interacting protein) and ERK1/2 and down-regulation of transforming growth factor beta 1 (TGFß1) and nuclear factor-κB (NF-κB) was determined in the myocardium, whereas expression of ERK1/2, periostin (Postn) and osteopontin increased in cardiac fibroblasts. U-0126 and los increased CHF survival by 75% compared with pred and placebo groups. U-0126 had both anti-fibrotic and anti-apoptotic effects, whereas los reduced fibrosis only. Myocardial FasL expression in mice activates differential robust fibrotic, apoptotic and inflammatory responses via ERK1/2 in cardiomyocytes and cardiac fibroblasts inducing DCM and CHF. Blocking the ERK1/2 pathway prevented progression of FasL-induced DCM and CHF by reducing fibrosis, inflammation and apoptosis in the myocardium.

[Endomyocardial biopsy should be performed in every patient with suspected myocarditis]. / La biopsia endomiocardica nella miocardite acuta: per tutti i pazienti.

The diagnosis of myocarditis is difficult because there is no pathognomonic clinical presentation and the disease may mimic other non-inflammatory diseases. Thus, current classifications on cardiomyopathies (e.g., the World Health Organization and the International Society and Federation of Cardiology [WHO/ISFC], the European Society of Cardiology [ESC], and the 2013 Expert Myocarditis ESC Task Force) define myocarditis as an inflammatory disease of the myocardium, which is diagnosed on endomyocardial biopsy (EMB) based upon histological, immunological, immunohistochemical and molecular tools. This will identify etiology, and differentiate between infectious, mainly viral, and non-infectious, immune-mediated forms. The term "inflammatory cardiomyopathy" may be applied in biopsy-proven myocarditis with associated left, right or biventricular dysfunction. Myocarditis may resolve spontaneously, relapse or become chronic progressing to dilated cardiomyopathy, death or heart transplantation. The 2013 Myocarditis ESC Task Force consensus document recommends consideration of EMB and selective coronary angiography in all patients with clinically suspected myocarditis according to the Task Force criteria. It is recommended that EMB analysis includes not only histology (Dallas criteria), but also immunohistology and detection of the genome of infectious agents by molecular tools. EMB should be performed by expert teams. The rationale for this diagnostic effort is the availability of a wide range of immunosuppressive or immunomodulatory agents that, as shown in systemic extracardiac autoimmune disease and in many clinical studies, can be used in infection-negative myocarditis patients to stop or at least stabilize chronic cardiac tissue damage mediated by the immune system, and thus prevent fibrosis and progression to irreversible end-stage dilated cardiomyopathy.

Complications of vitamin D deficiency from the foetus to the infant: One cause, one prevention, but who's responsibility?

Calcium and phosphorus represent building material for bones. The supplier of these bone minerals is the hormone calcitriol, which originates from vitamin D, itself made by sunshine in human skin. Requirement for bone minerals is highest during phases of rapid growth, and no one grows faster than the foetus and the infant, making them particularly vulnerable. Deprivation of calcium, whether through low calcium intake or low vitamin D, leads to serious health consequences throughout life, such as hypocalcaemic seizures, dilated cardiomyopathy, skeletal myopathy, congenital and infantile rickets, and osteomalacia. These 5 conditions are often summarised as 'symptomatic vitamin D deficiency', are fully reversible but also fully preventable. However, the increasing prevalence of rickets and osteomalacia, and the deaths from hypocalcaemic cardiomyopathy, demand action from global health care providers. Clarification of medical and parental responsibilities is a prerequisite to deliver successful prevention programmes. The foetus and infant have the human right to be protected against harm, and vitamin D supplementation has the same public health priority as vaccinations.

Mitochondrial reprogramming induced by CaMKIIδ mediates hypertrophy decompensation.

RATIONALE: Sustained activation of Gαq transgenic (Gq) signaling during pressure overload causes cardiac hypertrophy that ultimately progresses to dilated cardiomyopathy. The molecular events that drive hypertrophy decompensation are incompletely understood. Ca(2+)/calmodulin-dependent protein kinase II δ (CaMKIIδ) is activated downstream of Gq, and overexpression of Gq and CaMKIIδ recapitulates hypertrophy decompensation. OBJECTIVE: To determine whether CaMKIIδ contributes to hypertrophy decompensation provoked by Gq. METHODS AND RESULTS: Compared with Gq mice, compound Gq/CaMKIIδ knockout mice developed a similar degree of cardiac hypertrophy but exhibited significantly improved left ventricular function, less cardiac fibrosis and cardiomyocyte apoptosis, and fewer ventricular arrhythmias. Markers of oxidative stress were elevated in mitochondria from Gq versus wild-type mice and respiratory rates were lower; these changes in mitochondrial function were restored by CaMKIIδ deletion. Gq-mediated increases in mitochondrial oxidative stress, compromised membrane potential, and cell death were recapitulated in neonatal rat ventricular myocytes infected with constitutively active Gq and attenuated by CaMKII inhibition. Deep RNA sequencing revealed altered expression of 41 mitochondrial genes in Gq hearts, with normalization of ≈40% of these genes by CaMKIIδ deletion. Uncoupling protein 3 was markedly downregulated in Gq or by Gq expression in neonatal rat ventricular myocytes and reversed by CaMKIIδ deletion or inhibition, as was peroxisome proliferator-activated receptor α. The protective effects of CaMKIIδ inhibition on reactive oxygen species generation and cell death were abrogated by knock down of uncoupling protein 3. Conversely, restoration of uncoupling protein 3 expression attenuated reactive oxygen species generation and cell death induced by CaMKIIδ. Our in vivo studies further demonstrated that pressure overload induced decreases in peroxisome proliferator-activated receptor α and uncoupling protein 3, increases in mitochondrial protein oxidation, and hypertrophy decompensation, which were attenuated by CaMKIIδ deletion. CONCLUSIONS: Mitochondrial gene reprogramming induced by CaMKIIδ emerges as an important mechanism contributing to mitotoxicity in decompensating hypertrophy.

Lumbrokinase from earthworm extract ameliorates second-hand smoke-induced cardiac fibrosis.

Exposure to tobacco smoke has epidemiologically been linked to the occurrence of cardiovascular disease among nonsmokers but the associated molecular events are not well elucidated yet. When Sprague Dawley rats were exposed to second-hand tobacco cigarette smoke twice a day for a 30 days period at an exposure rate of 10 cigarettes/30 min, they showed adverse effects including reduced left ventricle weight, increased cardiac damages, deteriorated cardiac features, and cardiac fibrosis. Exposure to second-hand smoking (SHS) increased the molecular markers of cardiac fibrosis such as urokinase plasminogen activator and matrix metallopeptidases. The modulations in the protein levels were led by the activation of extracellular signal-regulated kinases (ERK1/2), the transcription factor-specificity protein 1 (SP1), and the fibrogenic master switch-connective for epithelial-mesenchymal transition tissue growth factor there by indicating their effective role in SHS-induced myocardial infraction. Dilong, an edible earthworm extract used in Chinese medicine and its bioactive fibrinolytic enzyme product-lumbrokinase, when administered in rats, restricted the SHS exposure induced cardiac fibrosis and provided cardio-protection. The results show that lumbrokinase and dilong administration can efficiently prevent epidemiological incidence of cardiac disease among SHS-exposed nonsmokers.

Ectopic trypsin in the myocardium promotes dilated cardiomyopathy after influenza A virus infection.

We have previously reported that ectopic trypsin in the myocardium triggers acute myocarditis after influenza A virus (IAV) infection. As myocarditis is a common precursor to dilated cardiomyopathy (DCM), the aim of the present study was to investigate the influence of trypsin on the progression of DCM after IAV infection. IAV-infected mice treated with saline or trypsin inhibitor were euthanized on days 0, 9, 20, 40 and 60 postinfection. Trypsin expression colocalized with myocardial inflammatory loci and IAV-induced myocarditis peaked on day 9 postinfection and alleviated by day 20 but persisted until day 60 postinfection, even though replication of IAV was not detected from day 20 postinfection. Similar time courses were observed for the activation of pro-matrix metalloproteinase (pro-MMP)-9 and expression of the proinflammatory cytokines IL-6, IL-1ß, and TNF-α. Degradation of collagen type I, proliferation of ventricular interstitial collagen, and expression of collagen type I and III mRNA increased significantly during acute and chronic phases; collagen type III mRNA increased more significantly than collagen type I mRNA. Cardiac function progressively deteriorated with progressive left ventricular dilation. The trypsin inhibitor aprotinin suppressed pro-MMP-9 activation and cytokine release, alleviated myocardial inflammation, and restored collagen metabolism during acute and chronic phases of myocarditis. This effectively prevented ventricular dilation and improved cardiac function. These results suggest that ectopic trypsin in the myocardium promoted DCM through chronic activation of pro-MMP-9, persistent induction of cytokines, and mediation of collagen remodeling. Pharmacological inhibition of trypsin activity might be a promising approach for the prevention of viral cardiomyopathy.

Cardiac electrophysiological alterations in heart/muscle-specific manganese-superoxide dismutase-deficient mice: prevention by a dietary antioxidant polyphenol.

Cardiac electrophysiological alterations induced by chronic exposure to reactive oxygen species and protective effects of dietary antioxidant have not been thoroughly examined. We recorded surface electrocardiograms (ECG) and evaluated cellular electrophysiological abnormalities in enzymatically-dissociated left ventricular (LV) myocytes in heart/muscle-specific manganese-superoxide dismutase-deficient (H/M-Sod2(-/-)) mice, which exhibit dilated cardiomyopathy due to increased oxidative stress. We also investigated the influences of intake of apple polyphenols (AP) containing mainly procyanidins with potent antioxidant activity. The QRS and QT intervals of ECG recorded in H/M-Sod2(-/-) mice were prolonged. The effective refractory period in the LV myocardium of H/M-Sod2(-/-) mice was prolonged, and susceptibility to ventricular tachycardia or fibrillation induced by rapid ventricular pacing was increased. Action potential duration in H/M-Sod2(-/-) LV myocytes was prolonged, and automaticity was enhanced. The density of the inwardly rectifier K(+) current (I K1) was decreased in the LV cells of H/M-Sod2(-/-) mice. The AP intake partially improved these electrophysiological alterations and extended the lifespan in H/M-Sod2(-/-) mice. Thus, chronic exposure of the heart to oxidative stress produces a variety of electrophysiological abnormalities, increased susceptibility to ventricular arrhythmias, and action potential changes associated with the reduced density of I K1. Dietary intake of antioxidant nutrients may prevent oxidative stress-induced electrophysiological disturbances.

Functional mitral regurgitation: therapeutic strategies for a ventricular disease.

Functional mitral regurgitation is a highly prevalent condition among patients with ischemic and dilated cardiomyopathies. Arising from remodeling of both the mitral valve annulus and the left ventricle, it is associated with high mortality and morbidity. In selected patients, cardiac resynchronization therapy helps to reduce functional mitral regurgitation, but surgical intervention remains the mainstay of therapy when medical therapy for left ventricular dysfunction has been inadequate. It is, however, associated with significant perioperative risks and does not alter long-term mortality. Percutaneous devices, and more recently the Mitraclip in particular, represent a promising alternative that can improve symptoms and ventricular remodeling with significantly lower periprocedural risk.

Mechanical and non-mechanical functions of Dystrophin can prevent cardiac abnormalities in Drosophila.

Dystrophin-deficiency causes cardiomyopathies and shortens the life expectancy of Duchenne and Becker muscular dystrophy patients. Restoring Dystrophin expression in the heart by gene transfer is a promising avenue to explore as a therapy. Truncated Dystrophin gene constructs have been engineered and shown to alleviate dystrophic skeletal muscle disease, but their potential in preventing the development of cardiomyopathy is not fully understood. In the present study, we found that either the mechanical or the signaling functions of Dystrophin were able to reduce the dilated heart phenotype of Dystrophin mutants in a Drosophila model. Our data suggest that Dystrophin retains some function in fly cardiomyocytes in the absence of a predicted mechanical link to the cytoskeleton. Interestingly, cardiac-specific manipulation of nitric oxide synthase expression also modulates cardiac function, which can in part be reversed by loss of Dystrophin function, further implying a signaling role of Dystrophin in the heart. These findings suggest that the signaling functions of Dystrophin protein are able to ameliorate the dilated cardiomyopathy, and thus might help to improve heart muscle function in micro-Dystrophin-based gene therapy approaches.

Rescue of heart lipoprotein lipase-knockout mice confirms a role for triglyceride in optimal heart metabolism and function.

Hearts utilize fatty acids as a primary source of energy. The sources of those lipids include free fatty acids and lipoprotein triglycerides. Deletion of the primary triglyceride-hydrolyzing enzyme lipoprotein lipase (LPL) leads to cardiac dysfunction. Whether heart LPL-knockout (hLPL0) mice are compromised due a deficiency in energetic substrates is unknown. To test whether alternative sources of energy will prevent cardiac dysfunction in hLPL0 mice, two different models were used to supply nonlipid energy. 1) hLPL0 mice were crossed with mice transgenically expressing GLUT1 in cardiomyocytes to increase glucose uptake into the heart; this cross-corrected cardiac dysfunction, reduced cardiac hypertrophy, and increased myocardial ATP. 2) Mice were randomly assigned to a sedentary or training group (swimming) at 3 mo of age, which leads to increased skeletal muscle production of lactate. hLPL0 mice had greater expression of the lactate transporter monocarboxylate transporter-1 (MCT-1) and increased cardiac lactate uptake. Compared with hearts from sedentary hLPL0 mice, hearts from trained hLPL0 mice had adaptive hypertrophy and improved cardiac function. We conclude that defective energy intake and not the reduced uptake of fat-soluble vitamins or cholesterol is responsible for cardiac dysfunction in hLPL0 mice. In addition, our studies suggest that adaptations in cardiac metabolism contribute to the beneficial effects of exercise on the myocardium of patients with heart failure.