Cardiac sarcoma. / Sarkom i hjertet.

BACKGROUND: Although very rare, cardiac sarcoma is the most common malignant cardiac tumour. Cardiac tumours may present with constitutional symptoms and this can lead to delayed diagnosis. CASE PRESENTATION: A woman in her late twenties was admitted to the acute psychiatric ward with suspected depressive psychosis. Although she presented with insomnia, auditory hallucinosis and paranoid delusions, her main symptoms were dyspnoea, tachycardia and exhaustion. She was discharged after 17 days and admitted directly to the medical ward for further examination. A thorough somatic examination, including diagnostic imaging, revealed a tumour in the left atrium obstructing the mitral ostium in the diastole, resulting in orthopnoea. She had urgent cardiac surgery and the histology was consistent with an intimal sarcoma. INTERPRETATION: This case illustrates a rare disease presenting with atypical symptoms. Her psychiatric symptoms resolved after surgery and oncologic treatment of her cardiac tumour.

Screening for symptoms of depression and anxiety in a cardiology department. / Screening for symptomer på depresjon og angst ved en hjertemedisinsk avdeling.

BACKGROUND: Depression and anxiety are common in patients with cardiac disease and predict a poorer prognosis, increased mortality and reduced compliance with treatment. National and international guidelines recommend procedures for screening, but there is a lack of studies of such practices in Norwegian hospitals. The objective of this study was to implement a simple screening method for symptoms of depression and anxiety in patients with cardiac disease. MATERIAL AND METHOD: Patients in the Department of Cardiology at Diakonhjemmet Hospital who had valvular heart disease, tachyarrhythmia, myocardial infarction or heart failure were screened for symptoms of depression, anxiety and panic attacks with the aid of five questions from the Patient Health Questionnaire-2 (PHQ-2), Generalized Anxiety Disorder Scale-2 (GAD-2) and Patient Health Questionnaire - Somatic, Anxiety, and Depressive Symptom Scales (PHQ-SADS). The patients were recruited from the outpatient clinic or ward at least one month after acute heart disease. RESULTS: A total of 57 of 232 patients reported symptoms of depression or anxiety when screened. The screening method was easy to implement, but time constraints and uncertainty regarding procedures for follow-up and the effect of following up the patients were reported. INTERPRETATION: Good tools and methods are available for screening for symptoms of depression and anxiety and anxiety in patients with cardiac disease. More studies are needed regarding the benefits of screening, at what stage of the disease it should be performed, and whether it should be performed by the primary and/or the specialist health services.

Palmitate promotes inflammatory responses and cellular senescence in cardiac fibroblasts.

Palmitate triggers inflammatory responses in several cell types, but its effects on cardiac fibroblasts are at present unknown. The aims of the study were to (1) assess the potential of palmitate to promote inflammatory signaling in cardiac fibroblasts through TLR4 and the NLRP3 inflammasome and (2) characterize the cellular phenotype of cardiac fibroblasts exposed to palmitate. We examined whether palmitate induces inflammatory responses in cardiac fibroblasts from WT, NLRP3-/- and ASC-/-mice (C57BL/6 background). Exposure to palmitate caused production of TNF, IL-6 and CXCL2 via TLR4 activation. NLRP3 inflammasomes are activated in a two-step manner. Whereas palmitate did not prime the NLRP3 inflammasome, it induced activation in LPS-primed cardiac fibroblasts as indicated by IL-1ß, IL-18 production and NLRP3-ASC co-localization. Palmitate-induced NLRP3 inflammasome activation in LPS-primed cardiac fibroblasts was associated with reduced AMPK activity, mitochondrial reactive oxygen species production and mitochondrial dysfunction. The cardiac fibroblast phenotype caused by palmitate, in an LPS and NLRP3 independent manner, was characterized by decreased cellular proliferation, contractility, collagen and MMP-2 expression, as well as increased senescence-associated ß-galactosidase activity, and consistent with a state of cellular senescence. This study establishes that in vitro palmitate exposure of cardiac fibroblasts provides inflammatory responses via TLR4 and NLRP3 inflammasome activation. Palmitate also modulates cardiac fibroblast functionality, in a NLRP3 independent manner, resulting in a phenotype related to cellular senescence. These effects of palmitate could be of importance for myocardial dysfunction in obese and diabetic patients.

Toll-Like Receptor 9 Promotes Survival in SERCA2a KO Heart Failure Mice.

Aim. Inflammation is important in heart failure (HF). The role of the immune receptor toll-like receptor 9 (TLR9) in HF is not understood and not investigated in diastolic HF. We investigated the role of TLR9 in a murine diastolic HF model caused by cardiomyocyte SERCA2a excision. Methods and Results. We crossed SERCA2a KO and TLR9 KO mice to generate four mouse lines. Tamoxifen-induced cardiomyocyte SERCA2a gene excision was carried out in mice, causing diastolic HF. After 7.6 weeks, cardiac functions and dimensions were analyzed by echocardiography and heart tissues were processed. HF mice depleted of TLR9 demonstrated reduced survival compared to SERC2a KO mice, with a median life expectancy of 58 days compared to 63 days. Both HF groups displayed increased left atrium size, lung weight, fetal gene expressions, monocyte/macrophage infiltration, and fibrosis. However, there were no significant differences between the groups. Conclusion. In mice with SERCA2a KO-induced diastolic HF, the absence of TLR9 reduced median life expectancy. The cause remains elusive, as all investigated HF parameters were unaltered. Still, these findings support a salutary role of TLR9 in some subsets of HF conditions and underline the importance for future studies on the mechanisms of TLR9 in diastolic HF.

Low Circulating Levels of Mitochondrial and High Levels of Nuclear DNA Predict Mortality in Chronic Heart Failure.

BACKGROUND: Mitochondrial DNA (mtDNA) and possibly nuclear DNA (nDNA) are released as danger-associated molecular patterns during cardiac stress, and may activate several innate immune receptors. The purpose of this study was to investigate the regulation of these danger-associated molecular patterns during human heart failure (HF). METHODS AND RESULTS: Plasma levels of mtDNA and nDNA from HF patients (n = 84) were analyzed by reverse transcriptase-polymerase chain reaction and compared with controls (n = 72). Increased levels of mtDNA were found in New York Heart Association (NYHA) I-II and NYHA III-IV. There was evidence of increased nDNA in NYHA III-IV compared with controls and NYHA I-II. Kaplan-Meier analysis revealed higher mortality in patients with high nDNA levels, whereas high levels of mtDNA were associated with survival. CONCLUSIONS: Plasma levels of mtDNA and nDNA are elevated in human HF associated with increased and decreased mortality, respectively. This study may suggest a rationale for exploring interventions within inflammatory signaling pathways activated by nucleic acids as novel targets in treatment of HF.

p38α regulates SERCA2a function.

cAMP-dependent protein kinase (PKA) regulates the L-type calcium channel, the ryanodine receptor, and phospholamban (PLB) thereby increasing inotropy. Cardiac contractility is also regulated by p38 MAPK, which is a negative regulator of cardiac contractile function. The aim of this study was to identify the mechanism mediating the positive inotropic effect of p38 inhibition. Isolated adult and neonatal cardiomyocytes and perfused rat hearts were utilized to investigate the molecular mechanisms regulated by p38. PLB phosphorylation was enhanced in cardiomyocytes by chemical p38 inhibition, by overexpression of dominant negative p38α and by p38α RNAi, but not with dominant negative p38ß. Treatment of cardiomyocytes with dominant negative p38α significantly decreased Ca(2+)-transient decay time indicating enhanced sarco/endoplasmic reticulum Ca(2+)-ATPase function and increased cardiomyocyte contractility. Analysis of signaling mechanisms involved showed that inhibition of p38 decreased the activity of protein phosphatase 2A, which renders protein phosphatase inhibitor-1 phosphorylated and thereby inhibits PP1. In conclusion, inhibition of p38α enhances PLB phosphorylation and diastolic Ca(2+) uptake. Our findings provide evidence for novel mechanism regulating cardiac contractility upon p38 inhibition.

Inflammatory cytokines in heart failure: mediators and markers.

Evidence from both experimental and clinical trials indicates that inflammatory mediators are of importance in the pathogenesis of chronic heart failure (HF) contributing to cardiac remodeling and peripheral vascular disturbances. Several studies have shown raised levels of inflammatory cytokines such as tumor necrosis factor (TNF)α, interleukin (IL)-1ß and IL-6 in HF patients in plasma and circulating leukocytes, as well as in the failing myocardium itself. There is strong evidence that these mediators are involved in processes leading to cardiac remodeling such as hypertrophy, fibrosis and apoptosis. Some of these cytokines can also give useful prognostic information as reliable biomarkers in this disorder. In general, immunomodulating treatments have, with a few exceptions, been neutral or even harmful. However, the negative results of anti-TNF studies, for instance, do not necessarily argue against the 'cytokine hypothesis'. These studies just underscore the challenges in developing treatment modalities that can modulate the cytokine network in HF patients and result in beneficial net effects. Future studies should identify the crucial actors and their mechanisms of action in the immunopathogenesis of chronic HF and, in particular, clarify the balance between adaptive and maladaptive effects of these molecules. Such studies are a prerequisite for the development of new treatment strategies that target inflammatory and immunopathogenic mechanisms in HF. In this review article, these issues are thoroughly discussed, and we also argue for the possibility of future therapeutic targets such as mediators in innate immunity, chemokines and mediators in matrix remodeling.

Impact of delayed type hypersensitivity arthritis on development of heart failure by aortic constriction in mice.

AIMS: Patients with rheumatoid arthritis (RA) have increased risk of heart failure (HF). The mechanisms and cardiac prerequisites explaining this association remain unresolved. In this study, we sought to determine the potential cardiac impact of an experimental model of RA in mice subjected to HF by constriction of the ascending aorta. METHODS: Aorta was constricted via thoracotomy and placement of o-rings with inner diameter 0.55 mm or 0.66 mm, or sham operated. RA-like phenotype was instigated by delayed-type hypersensitivity arthritis (DTHA) two weeks after surgery and re-iterated after additional 18 days. Cardiac magnetic resonance imaging (MRI) was performed before surgery and at successive time points throughout the study. Six weeks after surgery the mice were euthanized, blood and tissue were collected, organ weights were documented, and expression levels of cardiac foetal genes were analysed. In a supplemental study, DTHA-mice were euthanized throughout 14 days after induction of arthritis, and blood was analysed for important markers and mediators of RA (SAP, TNF-α and IL-6). In order to put the latter findings into clinical context, the same molecules were analysed in serum from untreated RA patients and compared to healthy controls. RESULTS: Significant elevations of inflammatory markers were found in both patient- and murine blood. Furthermore, the DTHA model appeared clinically relevant when compared to the inflammatory responses observed in three prespecified RA severity disease states. Two distinct trajectories of cardiac dysfunction and HF development were found using the two o-ring sizes. These differences were consistent by both MRI, organ weights and cardiac foetal gene expression levels. Still, no difference within the HF groups, nor within the sham groups, could be found when DTHA was induced. CONCLUSION: DTHA mediated systemic inflammation did not cause, nor modify HF caused by aortic constriction. This indicates other prerequisites for RA-induced cardiac dysfunction.

Adrenomedullin is increased in alveolar macrophages and released from the lungs into the circulation in severe heart failure.

Adrenomedullin (AM) is a potent vasorelaxing peptide with natriuretic, diuretic, and growth inhibitory properties. Plasma concentrations and myocardial AM expression are increased in heart failure (HF). Since AM and AM binding sites are abundantly expressed in the lungs, we investigated to what extent pulmonary AM and AM receptor subtypes [CRLR/RAMP2 (AM1) and CRLR/RAMP3 (AM2)] are changed in HF and whether the lungs contribute to the increased plasma concentrations of AM reported in HF. Pulmonary AM mRNA and protein expression were increased by 2.8- and 2.6-fold, respectively, whereas mRNA expression of RAMP2 and CRLR was decreased in rats with HF 7 days after induction of MI compared to sham-operated rats (P < 0.05). Pulmonary AM receptor density was substantially decreased in HF rats compared to sham (3.7 +/-0.6 vs. 29.9 +/- 1.1 fmol/mg membrane protein; P < 0.05). Immunoreactivities against AM and the AM receptor components CRLR, RAMP2, and RAMP3 in the pulmonary tissue were seen in vascular smooth muscle cells, vascular endothelial cells, and in alveolar macrophages. AM mRNA expression in alveolar macrophages obtained from HF rats by bronchoalveolar lavage was 2.9-fold higher than in sham-operated rats (P < 0.05). An even more substantial increase of AM mRNA expression was found in alveolar macrophages from patients with HF (10-fold, P < 0.05), and this increase displayed a negative correlation to left ventricular systolic function (P < 0.05). Furthermore, a net release of AM from the lungs into the circulation was only found in HF patients with the most severe left ventricular systolic dysfunction. Thus, our data demonstrate increased expression and decreased receptor binding of AM in the lungs in severe HF. Furthermore, our data indicate that alveolar macrophages are an important source of pulmonary AM in both experimental and clinical HF. Finally, a net release of AM from the lungs into the circulation was only found in patients with severe systolic dysfunction.

Gene therapy in heart failure.

With increasing knowledge of basic molecular mechanisms governing the development of heart failure (HF), the possibility of specifically targeting key pathological players is evolving. Technology allowing for efficient in vivo transduction of myocardial tissue with long-term expression of a transgene enables translation of basic mechanistic knowledge into potential gene therapy approaches. Gene therapy in HF is in its infancy clinically with the predominant amount of experience being from animal models. Nevertheless, this challenging and promising field is gaining momentum as recent preclinical studies in larger animals have been carried out and, importantly, there are 2 newly initiated phase I clinical trials for HF gene therapy. To put it simply, 2 parameters are needed for achieving success with HF gene therapy: (1) clearly identified detrimental/beneficial molecular targets; and (2) the means to manipulate these targets at a molecular level in a sufficient number of cardiac cells. However, several obstacles do exist on our way to efficient and safe gene transfer to human myocardium. Some of these obstacles are discussed in this review; however, it primarily focuses on the molecular target systems that have been subjected to intense investigation over the last decade in an attempt to make gene therapy for human HF a reality.

Increased systemic and myocardial expression of neutrophil gelatinase-associated lipocalin in clinical and experimental heart failure.

AIMS: Neutrophil gelatinase-associated lipocalin (NGAL or lipocalin-2) is a glycoprotein with bacteriostatic properties. Growing evidence suggests that NGAL may also be involved in cell survival, inflammation, and matrix degradation. We therefore aimed to investigate the role of NGAL in heart failure (HF). METHODS AND RESULTS: Our main findings were (i) patients with acute post-myocardial infarction (MI) HF (n = 236) and chronic HF (n = 150) had elevated serum levels of NGAL (determined by enzyme immunoassay), significantly correlated with clinical and neurohormonal deterioration, (ii) in patients with HF following acute MI, elevated NGAL levels of at baseline were associated with adverse outcomes (median of 27 months follow-up), (iii) in a rat model of post-MI HF, NGAL/lipocalin-2 gene expression was increased in the non-ischaemic part of the left ventricle primarily located to cardiomyocytes, (iv) strong NGAL immunostaining was found in cardiomyocytes within the failing myocardium both in experimental and clinical HF, (v) interleukin-1beta and agonists for toll-like receptors 2 and 4, representing components of the innate immune system, were potent inducers of NGAL/lipocalin-2 in isolated neonatal cardiomyocytes. CONCLUSION: Our demonstration of enhanced systemic and myocardial NGAL expression in clinical and experimental HF further support a role for innate immune responses in the pathogenesis of HF.

YKL-40 (Chitinase-3-Like Protein 1) Serum Levels in Aortic Stenosis.

BACKGROUND: Identification of novel biomarkers could provide prognostic information and improve risk stratification in patients with aortic stenosis (AS). YKL-40 (chitinase-3-like protein 1), a protein involved in atherogenesis, is upregulated in human calcific aortic valves. We hypothesized that circulating YKL-40 would be elevated and associated with the degree of AS severity and outcome in patients with symptomatic AS. METHODS: Plasma YKL-40 was analyzed in 2 AS populations, one severe AS (n=572) with outcome measures and one with mixed severity (n=67). YKL-40 expression in calcified valves and in an experimental pressure overload model was assessed. RESULTS: We found (1) patients with AS had upregulated circulating YKL-40 compared with healthy controls (median 109 versus 34 ng/mL, P<0.001), but levels were not related to the degree of AS severity. (2) High YKL-40 levels (quartile 4) were associated with long-term (median follow-up 4.7 years) all-cause mortality (adjusted hazard ratio, 1.93 [95% CI, 1.37-2.73], P<0.001). (3) YKL-40 protein expression in human calcific valves co-localized with its putative receptor IL-13rα2 in close proximity to valve interstitial cells. (4) Myocardial YKL-40 increased in experimental pressure overload (6-fold in decompensated versus sham mice). CONCLUSIONS: YKL-40 levels were elevated in AS and associated with mortality but not with other metrics of disease severity including the degree of AS severity. Despite scientific rationale for its role in AS, the clinical utility of circulating YKL-40 as a biomarker is limited. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01794832.

Increased expression of LIGHT/TNFSF14 and its receptors in experimental and clinical heart failure.

BACKGROUND: Clinical and experimental studies suggest a pathogenic role for inflammation in chronic heart failure (HF). LIGHT is a member of the tumour necrosis factor superfamily involved in innate and adaptive immune responses. AIMS: We sought to investigate a potential pathogenic role of LIGHT in chronic HF. METHODS: We used various clinical and experimental approaches including studies in post-infarction HF rats and in vitro studies of endothelial cells and peripheral blood mononuclear cells (PBMC). RESULTS: Our main findings were: (i) LIGHT and its receptors (i.e., HVEM and lymphotoxin-beta receptor) were regulated during experimental HF, with strong expression in the infarcted area accompanied by up-regulation of HVEM in cardiomyocytes and endothelial cells also in the non-ischaemic part of the left ventricle. (ii) Patients with chronic HF had significantly increased expression of LIGHT on CD3(+) T-cells accompanied by increased expression of HVEM on monocytes and within the failing myocardium. (iii) LIGHT induced interleukin (IL)-6 expression in endothelial cells. In HF patients, but not in healthy controls, such an IL-6-inducing effect was also seen in LIGHT activated PBMC. CONCLUSION: Our findings in both clinical and experimental HF may suggest a role for LIGHT signalling pathways in the progression of chronic HF involving IL-6-related mechanisms.

Induction of pulmonary connective tissue growth factor in heart failure is associated with pulmonary parenchymal and vascular remodeling.

OBJECTIVES: Pulmonary remodeling is a well recognized consequence of heart failure (HF). However, the cellular and molecular mechanisms orchestrating the structural alterations of the lungs in HF are poorly understood. We have previously reported induction of the profibrotic peptide connective tissue growth factor (CTGF) in myocardial tissue of rats with HF, suggesting a role of CTGF during myocardial remodeling. The aim of the present study was to explore the potential role of CTGF in pulmonary remodeling in HF. METHODS: Pulmonary tissue samples were obtained from rats with myocardial infarction (MI) subsequent to ligation of the left coronary artery. Real-time quantitative RT-PCR was employed to investigate mRNA levels. The cellular distribution of CTGF was analysed by immunohistochemistry. RESULTS: Seven days after induction of myocardial infarction (MI) and HF in rats we found 2.3-fold and 1.9-fold increase of pulmonary transforming growth factor-beta1 and procollagen alpha1(I) mRNA levels, respectively, and typical morphological characteristics of pulmonary remodeling including interstitial fibrosis and medial thickening of pulmonary arteries. Pulmonary CTGF mRNA levels were substantially elevated in HF rats compared to sham-operated rats (4-fold; P<0.05) and corresponded with similar increase (3-fold; P<0.05) of pulmonary CTGF protein contents. Immunohistochemical analysis revealed increased pulmonary anti-CTGF immunoreactivity in HF, with immunostaining predominantly localized to alveolar macrophages and interstitial fibroblasts. Isolated alveolar macrophages from HF rats demonstrated substantial induction of CTGF mRNA expression (16-fold; p<0.05). Interestingly, platelets caused robust induction of CTGF mRNA expression in alveolar macrophages upon co-culture in vitro. CONCLUSION: Pulmonary CTGF was substantially increased in parallel with pulmonary remodeling in rats with HF. Our data indicate that alveolar macrophages are a major source of increased pulmonary CTGF in HF and that CTGF may be a player in the profibrotic mechanisms associated with HF.

NEIL3-Dependent Regulation of Cardiac Fibroblast Proliferation Prevents Myocardial Rupture.

Myocardial infarction (MI) triggers a reparative response involving fibroblast proliferation and differentiation driving extracellular matrix modulation necessary to form a stabilizing scar. Recently, it was shown that a genetic variant of the base excision repair enzyme NEIL3 was associated with increased risk of MI in humans. Here, we report elevated myocardial NEIL3 expression in heart failure patients and marked myocardial upregulation of Neil3 after MI in mice, especially in a fibroblast-enriched cell fraction. Neil3-/- mice show increased mortality after MI caused by myocardial rupture. Genome-wide analysis of 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) reveals changes in the cardiac epigenome, including in genes related to the post-MI transcriptional response. Differentially methylated genes are enriched in pathways related to proliferation and myofibroblast differentiation. Accordingly, Neil3-/- ruptured hearts show increased proliferation of fibroblasts and myofibroblasts. We propose that NEIL3-dependent modulation of DNA methylation regulates cardiac fibroblast proliferation and thereby affects extracellular matrix modulation after MI.

Thalidomide attenuates the development of fibrosis during post-infarction myocardial remodelling in rats.

BACKGROUND: Inflammation plays a pathogenic role in the development of heart failure (HF). The aim of this study was to examine the effect of treatment with the immunomodulating drug thalidomide in a rat model for post-myocardial infarction (MI) HF. METHODS: Rats were subjected to MI by left coronary artery ligation or sham-operated. Seven days after surgical intervention rats were randomised to treatment with thalidomide or vehicle for 8 weeks. RESULTS: Our main findings were: (i) thalidomide treatment did not affect cardiac function or the hypertrophic response, as determined by haemodynamic measurements and heart chamber weights, respectively. (ii) HF rats treated with thalidomide had a minor reduction in septum and relative wall thickness (p<0.05), indicating an anti-remodelling effect. (iii) Thalidomide appeared to have immunostimulatory effects on the myocardium as evident by increased MIP-1alpha gene expression (p<0.05). (iv) Treating HF rats with thalidomide reduced myocardial collagen content, as assessed by markedly decreased levels of hydroxyproline ( approximately 40% reduction; p<0.05), accompanied by lower TGF-beta(1) gene expression (p<0.05). CONCLUSION: Although thalidomide had no effect on cardiac function, our results suggest that intervention with thalidomide may have beneficial effects in post-MI HF by attenuating collagen accumulation and development of myocardial fibrosis.

Mechanisms of elevated plasma endothelin-1 in CHF: congestion increases pulmonary synthesis and secretion of endothelin-1.

OBJECTIVE: The pulmonary circulation may contribute to elevated plasma levels of endothelin-1 (ET-1) in congestive heart failure (CHF). The aims of the present study were to determine the mechanisms of increased secretion of ET-1 from the pulmonary circulation in CHF. METHODS: Juvenile pigs were subjected to sham operation (n=9) or rapid cardiac pacing-induced CHF (215-240 bpm, n=15). RESULTS: Three weeks of rapid pacing led to significant left ventricular dilatation, increased cardiac filling pressures, and reduced contractility (CHF pigs). Arterial plasma ET-1 levels in the CHF pigs were increased 4-fold compared to sham pigs (P<0.001). Single-bolus multiple indicator-dilution experiments revealed that pulmonary synthesis and release of ET-1 was increased in CHF, while pulmonary clearance of plasma ET-1 remained unaltered despite significant reduction of pulmonary fractional extraction of plasma ET-1. Pulmonary ECE-1 isozyme activity (pmol.min-1.mg protein-1) was selectively increased in lower lobe segments of CHF pigs (2.0+/-0.3) compared to lower lobe segments of controls (1.1+/-0.1, P<0.02), and to upper lobe segments of CHF pigs (1.1+/-0.1, P<0.005), and correlated significantly with the wet/dry weight ratios of the pulmonary tissue samples (R=0.75, P<0.001), i.e. a marker of pulmonary congestion. Furthermore, alveolar macrophages in congested lobe segments were identified as likely sites of increased synthesis and release of ET-1. CONCLUSIONS: In rapid pacing-induced CHF, a complex cardiopulmonary interaction revealed by pulmonary congestion causes increased pulmonary production and secretion of ET-1 due to enhanced pulmonary ECE-1 activities. Pulmonary secretion of ET-1 during evolving CHF is an important contributor to elevated plasma ET-1 levels in the systemic circulation.

Induction of myocardial biglycan in heart failure in rats--an extracellular matrix component targeted by AT(1) receptor antagonism.

OBJECTIVE: Cardiac remodelling associated with congestive heart failure typically involves dilatation of the ventricular cavities, cardiomyocyte hypertrophy and alterations of extracellular matrix. Biglycan is an extracellular proteoglycan with several recently appreciated functions including cell adhesion, collagen fibril assembly, and growth factor interactions. The aims of this study were to investigate the regulation of biglycan expression and to elucidate the site(s) of synthesis of biglycan in myocardial tissue in an experimental model of heart failure (HF). METHODS: Myocardial tissue samples were obtained from rats with myocardial infarction (MI) subsequent to ligation of the left coronary artery. Northern blot analysis and real-time quantitative RT-PCR were employed to investigate mRNA levels. The cellular distribution of biglycan was analysed by in situ hybridisation and immunohistochemistry. RESULTS: Myocardial biglycan mRNA levels in non-ischemic tissue of both left and right ventricles of heart failure rats were substantially elevated as compared to sham-operated rats. Although expression levels peaked 7 days after MI (13-fold increase compared to the sham group, P<0.05), substantial elevations of biglycan mRNA were observed throughout the study period. Analysis of cellular distribution revealed that biglycan expression was confined to myocardial fibroblasts and vascular endothelial cells. In cardiac fibroblasts isolated from failing hearts, biglycan mRNA levels were markedly elevated compared with fibroblasts from sham-operated rats. In addition, in rats with ischemic heart failure treatment with the AT(1) receptor antagonist losartan (12.5 mg.kg(-1) b.i.d. per os, for 25 days) prevented the increase of myocardial biglycan as well as TGF-beta(1) mRNA. CONCLUSION: This report demonstrates global induction of myocardial biglycan mRNA in heart failure. Myocardial biglycan expression could be targeted by AT(1) receptor antagonism, an intervention well documented to halt cardiac remodelling in heart failure. Furthermore, the study provides evidence that angiotensin II is a regulator of biglycan expression in cardiac fibroblasts.

Sustained Toll-Like Receptor 9 Activation Promotes Systemic and Cardiac Inflammation, and Aggravates Diastolic Heart Failure in SERCA2a KO Mice.

AIM: Cardiac inflammation is important in the pathogenesis of heart failure. However, the consequence of systemic inflammation on concomitant established heart failure, and in particular diastolic heart failure, is less explored. Here we investigated the impact of systemic inflammation, caused by sustained Toll-like receptor 9 activation, on established diastolic heart failure. METHODS AND RESULTS: Diastolic heart failure was established in 8-10 week old cardiomyocyte specific, inducible SERCA2a knock out (i.e., SERCA2a KO) C57Bl/6J mice. Four weeks after conditional KO, mice were randomized to receive Toll-like receptor 9 agonist (CpG B; 2µg/g body weight) or PBS every third day. After additional four weeks, echocardiography, phase contrast magnetic resonance imaging, histology, flow cytometry, and cardiac RNA analyses were performed. A subgroup was followed, registering morbidity and death. Non-heart failure control groups treated with CpG B or PBS served as controls. Our main findings were: (i) Toll-like receptor 9 activation (CpG B) reduced life expectancy in SERCA2a KO mice compared to PBS treated SERCA2a KO mice. (ii) Diastolic function was lower in SERCA2a KO mice with Toll-like receptor 9 activation. (iii) Toll-like receptor 9 stimulated SERCA2a KO mice also had increased cardiac and systemic inflammation. CONCLUSION: Sustained activation of Toll-like receptor 9 causes cardiac and systemic inflammation, and deterioration of SERCA2a depletion-mediated diastolic heart failure.