Current Understanding of the Pathophysiology of Myocardial Fibrosis and Its Quantitative Assessment in Heart Failure

Changes in the number of mast cells, expression of fibroblast growth factor-2 and extent of interstitial fibrosis in established and advanced hypertensive heart disease

INTRODUCTION

An increasing number of studies have shed light on the role of cardiac mast cells in the pathogenesis of hypertension-induced myocardial remodeling. Mast cells promote fibroblast activation, myofibroblast differentiation and subsequent collagen accumulation through the action of tryptase, chymase, histamine and fibroblast growth factor-2. The aim of the present study was to report on the changes in the number of mast cells as evaluated through toluidine blue, tryptase and c-kit staining, to assess the extent of interstitial fibrosis and correlate it with the changes in the number of mast cells and to analyze the immunohistochemical expression of fibroblast growth factor-2 in two groups of spontaneously hypertensive rats indicative of established and advanced hypertensive heart disease. A novel aspect of our work was the analysis of all parameters in the right ventricle.

MATERIAL AND METHODS

For the present study, we used 6- and 12-month-old spontaneously hypertensive rats. A light microscopic study was conducted on sections stained with hematoxylin and eosin and toluidine blue. For the immunohistochemical study we used monoclonal antibodies against mast cell tryptase and fibroblast growth factor-2 and a polyclonal antibody against c-kit. The expression of fibroblast growth factor-2 was assessed semi-quantitatively through ImageJ. The number of mast cells was evaluated on toluidine blue-, tryptase- and c-kit-stained sections and a comparative statistical analysis with the Mann-Whitney test was conducted between the two age groups. A separate statistical analysis between results obtained through immunostaining for tryptase and for c-kit was conducted in each age group with the Wilcoxon signed-rank test. The extent of fibrosis was assessed quantitatively on slides stained with Mallory's trichrome stain as a percentage of the whole tissue and compared between the two age groups. Spearman's correlation was used to test whether a correlation exists between the number of mast cells and the percentage of interstitial fibrosis.

RESULTS

Mast cells with typical cytoplasmic granules were visualized in the interstitial tissue and in the perivascular zone in both age groups. In both ventricles, their number increased significantly in 12-month-old animals as evaluated through all three staining methods. Moreover, immunostaining for tryptase and for c-kit yielded comparable results. The immunoreactivity of fibroblast growth factor-2 increased in both ventricles in older animals. Expression of this protein was particularly intensive in the cytoplasm of connective tissue cells with the characteristic features of mast cells mainly found in the areas of fibrotic alterations in 12-month-old spontaneously hypertensive rats. In both ventricles, interstitial fibrosis was more extensive throughout the myocardium of older animals and was positively correlated with the changes in the number of mast cells in both age groups.

CONCLUSION

The present study reported for the first time that the increase in the number of mast cells, observed as hypertension-induced myocardial changes progress, is statistically significant and confirmed that this process takes place in both ventricles. This increase is accompanied by a higher expression of fibroblast growth factor-2 and is more strongly correlated with the more pronounced interstitial fibrosis in older animals, further supporting the role of mast cells in the structural changes taking place in the myocardium in response to systemic hypertension.

Quantitative fragmented QRS has a good diagnostic value on myocardial fibrosis in hypertrophic obstructive cardiomyopathy based on clinical-pathological study

Background

To investigate the relationship between fragmented QRS (fQRS) quantified by a new method and myocardial fibrosis (MF) and the diagnostic value of quantitative fQRS (Q-fQRS) to detect MF in hypertrophic obstructive cardiomyopathy (HOCM) patients based on histological validation.

Methods

We performed a retrospective study that included 69 patients with HOCM who underwent ventricular septal surgery. Nine individuals who died from accidents were studied as a control reference for the histological parameters. Septal myocardium samples were subjected to Masson’s trichrome staining to quantify the collagen volume fraction (CVF). An fQRS pattern was defined as the presence of additional R waves or RSR’, evidenced by notched R or S wave on electrocardiography (ECG). The Q-fQRS was quantified as the total amount of deflections in the QRS complex in all 12 routine ECG leads together. Cardiac magnetic resonance imaging was conducted, and late gadolinium enhancement (LGE) was measured at 2, 4, 6 and 8 standard deviations (SDs).

Results

Of the 69 patients, fQRS was documented in 38 (55.1%) patients, the mean number of leads with fQRS was 3.7 ± 1.6, and the mean Q-fQRS was 17 ± 7.2. Compared with HOCM patients without fQRS, HOCM patients with fQRS had a higher CVF and more LGE at 6 SD (P < 0.001; P = 0.040). Q-fQRS was correlated with CVF (r = 0.640, P < 0.001), and Q-fQRS showed the best correlation with LGE measured at 8 SD (r = 0.379, P = 0.002). Multivariate regression analyses revealed that Q-fQRS was independently associated with the extent of CVF in HOCM patients after adjusting for age, sex, body surface area and the extent of LGE at 6 SD (P < 0.001). When the patients were divided into subgroups with normal CVF or high CVF according to the CVF in controls, Q-fQRS and LGE at 6SD showed similar diagnostic value in detecting patients with high CVF, with sensitivities of 66.7% vs 68.6%, specificities of 76.7% vs 72.4%, and accuracies of 71% vs 70.3%.

Conclusions

HOCM patients with fQRS showed more extensive MF. Q-fQRS was an independent predictor for MF and had a good diagnostic value, with a sensitivity of 66.7% and specificity of 76.7%, in identifying patients with higher fibrotic burden.

Mutations in TRIM63 cause an autosomal-recessive form of hypertrophic cardiomyopathy

OBJECTIVE

Up to 50% of patients with hypertrophic cardiomyopathy (HCM) show no disease-causing variants in genetic studies. TRIM63 has been suggested as a candidate gene for the development of cardiomyopathies, although evidence for a causative role in HCM is limited. We sought to investigate the relationship between rare variants in TRIM63 and the development of HCM.

METHODS

TRIM63 was sequenced by next generation sequencing in 4867 index cases with a clinical diagnosis of HCM and in 3628 probands with other cardiomyopathies. Additionally, 3136 index cases with familial cardiovascular diseases other than cardiomyopathy (mainly channelopathies and aortic diseases) were used as controls.

RESULTS

Sixteen index cases with rare homozygous or compound heterozygous variants in TRIM63 (15 HCM and one restrictive cardiomyopathy) were included. No homozygous or compound heterozygous were identified in the control population. Familial evaluation showed that only homozygous and compound heterozygous had signs of disease, whereas all heterozygous family members were healthy. The mean age at diagnosis was 35 years (range 15-69). Fifty per cent of patients had concentric left ventricular hypertrophy (LVH) and 45% were asymptomatic at the moment of the first examination. Significant degrees of late gadolinium enhancement were detected in 80% of affected individuals, and 20% of patients had left ventricular (LV) systolic dysfunction. Fifty per cent had non-sustained ventricular tachycardia. Twenty per cent of patients suffered an adverse cerebrovascular event (20%).

CONCLUSION

TRIM63 appears to be an uncommon cause of HCM inherited in an autosomal-recessive manner and associated with concentric LVH and a high rate of LV dysfunction.

Non-ischemic dilated cardiomyopathy and cardiac fibrosis

Cardiac fibrosis is associated with non-ischemic dilated cardiomyopathy, increasing its morbidity and mortality. Cardiac fibroblast is the keystone of fibrogenesis, being activated by numerous cellular and humoral factors. Macrophages, CD4+ and CD8+ T cells, mast cells, and endothelial cells stimulate fibrogenesis directly by activating cardiac fibroblasts and indirectly by synthetizing various profibrotic molecules. The synthesis of type 1 and type 3 collagen, fibronectin, and α-smooth muscle actin is rendered by various mechanisms like transforming growth factor-beta/small mothers against decapentaplegic pathway, renin angiotensin system, and estrogens, which in turn alter the extracellular matrix. Investigating the underlying mechanisms will allow the development of diagnostic and prognostic tools and discover novel specific therapies. Serum biomarkers aid in the diagnosis and tracking of cardiac fibrosis progression. The diagnostic gold standard is cardiac magnetic resonance with gadolinium administration that allows quantification of cardiac fibrosis either by late gadolinium enhancement assessment or by T1 mapping. Therefore, the goal is to stop and even reverse cardiac fibrosis by developing specific therapies that directly target fibrogenesis, in addition to the drugs used to treat heart failure. Cardiac resynchronization therapy had shown to revert myocardial remodeling and to reduce cardiac fibrosis. The purpose of this review is to provide an overview of currently available data.

Mangiferin exert cardioprotective and anti-apoptotic effects in heart failure induced rats

Mangiferin is a well-known xanthone extracted from mango leaves (Mangifera indica Linn). Mangiferin is widely distributed in the bark, peel, leaf, seed, stalk, and kernel of mango and higher plants. The pharmacological properties of mangiferin, including its antioxidant, anticancer, antiaging, antiviral, hepatoprotective, analgesic, and immunomodulatory activities, have been described in several studies. We investigated the effect of mangiferin on isoproterenol-induced apoptosis. Experimental heart failure was induced in rats by intraperitoneal administration of isoproterenol (5 mg/kg) for 7 consecutive days. Rats were divided into five groups: group I (sham rats), group II (isoproterenol alone control), group III (isoproterenol + 25 mg/kg mangiferin), group IV (isoproterenol + 50 mg/kg mangiferin), and group V (isoproterenol + 0.0225 mg/kg digitalis as a positive control). Hemodynamic parameters and body weight, heart weight and liver weight, apoptosis induction, and caspase-3, Bax, and Bcl-2 protein levels were measured, and a histopathological analysis of cardiomyocytes was performed. In addition, apoptosis and protein expression of caspase-3, cleaved caspase-3, Bax, and Bcl-2 were measured in cardiac H9c2 cells. Mangiferin supplementation significantly increased heart rate and improved the maximum rate of decrease in left ventricular (LV) pressure, the maximum rate of increase in LV pressure, and LV systolic pressure. Mangiferin reduced inflammatory cell infiltration and the number of broken myocardial fibers, and decreased apoptosis in cardiomyocytes by reducing proteins levels of caspase-3 and Bax and increasing those of Bcl-2. Our findings suggest that mangiferin has a cardioprotective effect against isoproterenol-induced apoptosis in cardiomyocytes.

HIV-related cardiovascular diseases: the search for a unifying hypothesis

Although the extensive rollout of antiretroviral (ARV) therapy resulted in a longer life expectancy for people living with human immunodeficiency virus (PLHIV), such individuals display a relatively increased occurrence of cardiovascular diseases (CVD). This health challenge stimulated significant research interests in the field, leading to an improved understanding of both lifestyle-related risk factors and the underlying mechanisms of CVD onset in PLHIV. However, despite such progress, the precise role of various risk factors and mechanisms underlying the development of HIV-mediated CVD still remains relatively poorly understood. Therefore, we review CVD onset in PLHIV and focus on 1) the spectrum of cardiovascular complications that typically manifest in such persons and 2) underlying mechanisms that are implicated in this process. Here, the contributions of such factors and modulators and underlying mechanisms are considered in a holistic and integrative manner to generate a unifying hypothesis that includes identification of the core pathways mediating CVD onset. The review focuses on the sub-Saharan African context, as there are relatively high numbers of PLHIV residing within this region, indicating that the greater CVD risk will increasingly threaten the well-being and health of its citizens. It is our opinion that such an approach helps point the way for future research efforts to improve treatment strategies and/or lifestyle-related modifications for PLHIV.

Diffuse myocardial fibrosis and the prognosis of heart failure with reduced ejection fraction in Chinese patients: a cohort study

Evidence regarding the relationship between diffuse myocardial fibrosis and the prognosis of heart failure with reduced ejection fraction (HFrEF) was limited. Therefore, this study set out to investigate whether diffuse myocardial fibrosis was independently related to the prognosis of failure with reduced ejection fraction in Chinese patients after adjusting for other covariates. The present study was a cohort study. A total of 45 consecutive HFrEF patients were involved in Zhongshan Hospital of Fudan University in China from 1/9/2015 to 31/12/2016. The target-independent variable was extracellular volume (ECV) quantified by cardiac magnetic resonance T1 mapping using the modified Look-Locker inversion recovery (MOLLI) sequence at baseline. To assess the prognostic impact of MOLLI-ECV, its association with hospitalization for heart failure/cardiac death was tested by multivariable Cox regression analysis. Covariates involved in this study included age, gender, body mass index, heart rate, systolic blood pressure diastolic blood pressure, smoking, hypertension, diabetes mellitus, etiology, NYHA functional class, blood urea nitrogen, creatinine, serum uric acid, total bilirubin, and growth stimulation-expressed gene 2. Ten age- and sex-matched healthy participants with no history of cardiovascular disease served as a control group. Mean MOLLI-ECV was significantly higher in HFrEF patients versus healthy controls (29.55 ± 1.46% vs. 23.17 ± 1.93%, P < 0.001). Patients were followed for 9 months, during which the primary outcome (cardiac death or first heart failure hospitalization) occurred in 15 patients. By Kaplan-Meier analysis, patients with high MOLLI-ECV ≥ 30.10% had shorter event-free survival than the middle (MOLLI-ECV between 30.10 and 28.60) and low (MOLLI-ECV < 28.60) MOLLI-ECV patients (log-rank, P = 0.0035). Result of fully-adjusted multivariable Cox regression analysis showed MOLLI-ECV was positively associated with the composite outcome of HFrEF patients after adjusting confounders hazard ratio (HR) 2.57, 95% CI (1.09, 6.04). By subgroup analysis, a stronger association was seen in patients who with NYHA functional class III-IV, hematocrit < 39.8%, left atrial diameter ≥ 53.5 mm, or without the medical history of MRA or diuretics other than MRA. The P for interaction was < 0.05. In HFrEF patients, the relationship between MOLLI-ECV determined by CMR and the composite outcome is linear. High MOLLI-ECV was associated with a higher rate of cardiac mortality and first HF hospitalization in the short term follow up.

Cardiac Fibroblasts and Cardiac Fibrosis: Precise Role of Exosomes

Exosomes are a group of extracellular microvesicles that deliver biologically active RNAs, proteins, lipids and other signaling molecules to recipient cells. Classically, exosomes act as a vehicle by which cells or organs communicate with each other to maintain cellular/tissue homeostasis and to respond to pathological stress. Most multicellular systems, including the cardiovascular system, use exosomes for intercellular communication. In heart, endogenous exosomes from cardiac cells or stem cells aid in regulation of cell survival, cell proliferation and cell death; and thus tightly regulate cardiac biology and repair processes. Pathological stimulus in heart alters secretion and molecular composition of exosomes, thus influencing the above processes. The past decade has yielded increasing interest in the role of exosomes in the cardiovascular system and significant contribution of cardiac fibroblast (CF) and mediated cardiac fibrosis in heart failure, in this review we had overviewed the relevant literatures about fibroblast exosomes, its effect in the cardiovascular biology and its impact on cardiovascular disease (CVD). This review briefly describes the communication between fibroblasts and other cardiac cells via exosomes, the influence of such on myocardial fibrosis and remodeling, and the possibilities to use exosomes as biomarkers for acute and chronic heart diseases.

Idiopathic Myocardial Fibrosis in Captive Chimpanzees (Pan troglodytes)

Cardiovascular disorders and predominantly idiopathic myocardial fibrosis are frequently associated with mortality among zoo-housed chimpanzees (Pan troglodytes). Formalin-fixed whole hearts of deceased chimpanzees housed in zoos (n = 33) and an African sanctuary (n = 2) underwent detailed macroscopic and histopathologic examination using a standardized protocol. Archived histological slides from the hearts of 23 additional African sanctuary-housed chimpanzees were also examined. Myocardial fibrosis (MF) was identified in 30 of 33 (91%) of the zoo-housed chimpanzees but none of the 25 sanctuary-housed chimpanzees. MF was shown to be characterized by both interstitial and replacement fibrosis. Immunophenotyping demonstrated that the fibrotic lesions were accompanied by the increased presence of macrophages, alpha smooth muscle actin-positive myofibroblasts, and a minimal to mild T-cell-dominant leukocyte infiltration. There was no convincing evidence of cardiotropic viral infection or suggestion that diabetes mellitus or vitamin E or selenium deficiency were associated with the presence of the lesion. However, serum vitamin D concentrations among zoo-housed chimpanzees were found to be lower in seasons of low ultraviolet light levels.

The effectiveness of cardiac rehabilitation in non-ischemic dilated cardiomyopathy patients: A pilot study

BACKGROUND/PURPOSE

We aimed to investigate the efficacy of cardiac rehabilitation (CR) through parameters of cardiopulmonary exercise testing (CPET) and echocardiography in non-ischemic dilated cardiomyopathy (DCM) patients.

METHODS

We retrospectively identified non-ischemic DCM patients through medical records (between October 2011 and October 2018) in rehabilitation outpatient-clinics. Patients were divided into rehabilitation and control groups. Patients in the rehabilitation group eligible for inclusion had CR for 3-6 months. Control group patients were without rehabilitation. We recorded CPET and echocardiography parameters at the baseline and follow-up time-points. For safety evaluation, we investigated all adverse effects during training sessions. We utilized Mann-Whitney U test for between- and Wilcoxon signed-rank test for within-group comparisons.

RESULTS

Twenty-five patients (14 in rehabilitation and 11 in control group) were included. In the rehabilitation group, significantly increased peak V˙O₂/kg, peak V˙O₂%, peak workload and peak O₂ pulse were observed after completing CR, and echocardiographic parameters including left ventricular ejection fraction and end-systolic volume. Rehabilitation group patients demonstrated better improvement (change from the baseline) in peak V˙O₂/kg, peak V˙O₂% and peak workload vs. control. No adverse effects during rehabilitation trainings were observed.

CONCLUSION

For non-ischemic DCM, rehabilitation led to superior cardiopulmonary outcomes vs. no rehabilitation, without adverse effects.

Role of Inflammatory Cell Subtypes in Heart Failure

Inflammation is a well-known feature of heart failure. Studies have shown that while some inflammation is required for repair during injury and is protective, prolonged inflammation leads to myocardial remodeling and apoptosis of cardiac myocytes. Various types of immune cells are implicated in myocardial inflammation and include neutrophils, macrophages, eosinophils, mast cells, natural killer cells, T cells, and B cells. Recent clinical trials have targeted inflammatory cascades as therapy for heart failure with limited success. A better understanding of the temporal course of the infiltration of the different immune cells and their contribution to the inflammatory process may improve the success for therapy. This brief review outlines the major cell types involved in heart failure, and some of their actions are summarized in the supplementary figure.

Electrocardiographic Fragmented Activity (II): A Machine Learning Approach to Detection

Hypertrophic cardiomyopathy, according to its prevalence, is a comparatively common disease related to the risk of suffering sudden cardiac death, heart failure and stroke. This illness is characterized by the excessive deposition of collagen among healthy myocardium cells. This situation, which is medically known as fibrosis, constitutes effective conduction obstacles in the myocardium electrical path, and when severe enough, it can be outlined as additional peaks or notches in the QRS, clinically entitled as fragmentation. Nowadays, the fragmentation detection is performed by visual inspection, but the fragmented QRS can be confused with the noise present in the electrocardiogram (ECG). On the other hand, fibrosis detection is performed by magnetic resonance imaging with late gadolinium enhancement, the main drawback of this technique being its cost in terms of time and money. In this work, we propose two automatic algorithms, one for fragmented QRS detection and another for fibrosis detection. For this purpose, we used four different databases, including the subrogated database described in the companion paper and incorporating three additional ones, one compounded by more accurate subrogated ECG signals and two compounded by real and affected subjects as labeled by expert clinicians. The first real-world database contains QRS fragmented records and the second one contains records with fibrosis and both were recorded in Hospital Clínico Universitario Virgen de la Arrixaca (Spain). To deeply analyze the scope of these datasets, we benchmarked several classifiers such as Neural Networks, Support Vector Machines (SVM), Decision Trees and Gaussian Naïve Bayes (NB). For the fragmentation dataset, the best results were 0.94 sensitivity, 0.88 specificity, 0.89 positive predictive value, 0.93 negative predictive value and 0.91 accuracy when using SVM with Gaussian kernel. For the fibrosis databases, more limited accuracy was reached, with 0.47 sensitivity, 0.91 specificity, 0.82 predictive positive value, 0.66 negative predictive value and 0.70 accuracy when using Gaussian NB. Nevertheless, this is the first time that fibrosis detection is attempted automatically from ECG postprocessing, paving the way towards improved algorithms and methods for it. Therefore, we can conclude that the proposed techniques could offer a valuable tool to clinicians for both fragmentation and fibrosis diagnoses support.

QiShenYiQi Pills® ameliorates ischemia/reperfusion-induced myocardial fibrosis involving RP S19-mediated TGFβ1/Smads signaling pathway

QiShenYiQi Pills (QSYQ) is a compound Chinese medicine widely used in China for treatment of cardiovascular disease. However, limited data are available regarding the anti-fibrotic role of QSYQ after ischemia/reperfusion (I/R) injury. This study aimed to investigate the effect of post-treatment with QSYQ on myocardial fibrosis after I/R-induced myocardium injury, and the role of different compounds of QSYQ, focusing especially on the involvement of chemokine ribosomal protein S19 (RP S19) dimer and monocyte migration. Male Sprague-Dawley rats were subjected to left anterior descending coronary artery occlusion for 30 min followed by reperfusion with or without administration of QSYQ (0.6, 1.2, or 1.8 g/kg) once daily by gavage for 6 days. Post-treatment with QSYQ diminished I/R-induced infarct size, alleviated myocardium injury, attenuated myocardial fibrosis after 6 days of reperfusion, and restored heart function and myocardial blood flow after I/R. In addition, the drug significantly inhibited monocyte infiltration and macrophage polarization towards M2, which was attributable to chemokine RP S19 dimer. Moreover, Western blots revealed that QSYQ blocked I/R-induced increase in TGFβ1 and TGFβRⅡ and reversed its relevant gene expression, such as Smad3,4,6,7, and inhibited the increase of MMP 2,9 expression. As the major components of QSYQ, astragaloside IV (AsIV), 3,4-dihydroxy-phenyl lactic acid (DLA), and notoginsenoside R1 (R1) were assessed as to the contribution of each of them to the expression of the proteins concerned. The results showed that the effect of AsIV was similar to QSYQ, while DLA and R1 only partly simulated the effect of QSYQ. The results provide evidence for the potential role of QSYQ in treating myocardial fibrosis following I/R injury. This effect may be associated with QSYQ's inhibition effect on monocyte chemotaxis and TGFβ1/Smads signaling pathway with different component targeting distinct link (s) of the signaling.

Phosphorylation of Hsp20 Promotes Fibrotic Remodeling and Heart Failure

Cardiomyocyte-specific increases in phosphorylated Hsp20 (S16D-Hsp20) to levels similar to those observed in human failing hearts are associated with early fibrotic remodeling and depressed left ventricular function, symptoms which progress to heart failure and early death. The underlying mechanisms appear to involve translocation of phosphorylated Hsp20 to the nucleus and upregulation of interleukin (IL)-6, which subsequently activates cardiac fibroblasts in a paracrine fashion through transcription factor STAT3 signaling. Accordingly, treatment of S16D-Hsp20 mice with a rat anti-mouse IL-6 receptor monoclonal antibody (MR16-1) attenuated interstitial fibrosis and preserved cardiac function. These findings suggest that phosphorylated Hsp20 may be a potential therapeutic target in heart failure.

Application of G-CSF in Congestive Heart Failure Treatment

INTRODUCTION

Congestive Heart Failure (CHF) is a disorder in which the heart is unable to supply enough blood for body tissues. Since heart is an adaptable organ, it overcomes this condition by going under remodeling process. Considering cardiac myocytes are capable of proliferation after MI, stimulation of neovascularization as well as their regeneration might serve as a novel target in cardiac remodeling prevention and CHF treatment. Granulocyte Colony-Stimulating Factor (G-CSF), is a hematopoietic cytokine that promotes proliferation and differentiation of neutrophils and is involved in cardiac repair after MI. So far, this is the first review to focus on GCSF as a novel treatment for heart failure.

METHODS

We conducted a search of some databases such as PubMed for articles and reviews published between 2003 and 2017, with different keywords including "G-CSF", "congestive heart failure", "new therapies for CHF", "filgrastim", "in vivo study".

RESULTS

GCSF exerts its beneficial effects on cardiac repair through either stem cell mobilization or direct angiogenesis promotion. All of which are capable of promoting cardiac cell repair.

CONCLUSION

GCSF is a promising target in CHF-therapy by means of cardiac repair and remodeling prevention through multiple mechanisms, which are effective enough to be used in clinical practice.

Syndecan-1 as an independent risk factor for the incidence of adverse cardiovascular events in patients having stage C and D heart failure with non-ischemic dilated cardiomyopathy

BACKGROUND

Patients with heart failure (HF) having non-ischemic dilated cardiomyopathy (DCM) have high mortality rates. Syndecan-1 is reportedly associated with cardiac fibrosis and inflammation. This study explored the role of syndecan-1 in patients with non-ischemic DCM.

METHODS

Patients with HF were prospectively enrolled. Comprehensive clinical and biochemical analysis were performed. All patients were followed up for composite of major adverse cardiac events of cardiovascular death and cardiac transplantation.

RESULTS

We measured syndecan-1 levels in 96 patients with HF and non-ischemic DCM. The primary outcome was the 3-year major adverse cardiac events. Approximately, 71% of patients were men with mean age and LVEF of 51.08 ± 13.28 years and 31.90 ± 8.85%, respectively. Median syndecan-1 levels were 456.57 pg/ml (interquartile range, 244.93-1181.26 pg/ml). Multivariate Cox regression analysis for Model I (adjusted for age, sex) and II (adjusted for traditional confounding factors) revealed that baseline syndecan-1 remained an independent predictor of composite endpoint events (Model I HR, 1.10/100 pg/ml increase in syndecan-1 level, 95% CI, 1.04-1.16, P = 0.0006; Model II HR, 1.10/100 pg/ml increase in syndecan-1 level, 95% CI, 1.03-1.18, P = 0.0029). Kaplan Meier analysis based on syndecan-1 tertiles revealed that the top tertile was associated with reduced survival compare to that in middle and bottom tertiles (P < 0.0001). Multivariate logistic regression analyses showed a positive correlation between syndecan-1 level and fibrosis and inflammatory markers.

CONCLUSION

In patients with HF and non-ischemic DCM, the syndecan-1 level is important in the assessment of risk of adverse clinical outcome, and syndecan-1 level is correlated with fibrosis and inflammatory biomarkers.

Dysregulation of IL-33/ST2 signaling and myocardial periarteriolar fibrosis

Microvascular dysfunction in the heart and its association with periarteriolar fibrosis may contribute to the diastolic dysfunction seen in heart failure with preserved ejection fraction. Interleukin-33 (IL-33) prevents global myocardial fibrosis in a pressure overloaded left ventricle by acting via its receptor, ST2 (encoded by the gene, Il1rl1); however, whether this cytokine can also modulate periarteriolar fibrosis remains unclear. We utilized two approaches to explore the role of IL-33/ST2 in periarteriolar fibrosis. First, we studied young and old wild type mice to test the hypothesis that IL-33 and ST2 expression change with age. Second, we produced pressure overload in mice deficient in IL-33 or ST2 by transverse aortic constriction (TAC). With age, IL-33 expression increased and ST2 expression decreased. These alterations accompanied increased periarteriolar fibrosis in aged mice. Mice deficient in ST2 but not IL-33 had a significant increase in periarteriolar fibrosis following TAC compared to wild type mice. Thus, loss of ST2 signaling rather than changes in IL-33 expression may contribute to periarteriolar fibrosis during aging or pressure overload, but manipulating this pathway alone may not prevent or reverse fibrosis.

The association between physical activity and cardiac performance is dependent on age: the Copenhagen City Heart Study

This study aimed to test the hypothesis that regular physical activity is associated with improved cardiac function measured by tissue Doppler imaging (TDI) in the general population. Within a large prospective community-based population study, cardiac function was assessed in 2221 persons by TDI. Longitudinal displacement (LD), early diastolic velocity (e'), and myocardial performance index (MPI) was obtained by TDI. Linear univariable and multivariable regression analyses were performed in relation to age groups (< 50 years, 50-65 years, > 65 years) and self-reported level of physical activity: I (inactivity), II (light activity), III (moderate activity), and IV (high-level activity). Participants < 50 years in the most active group had significantly better cardiac performance when compared to all other activity levels (higher levels of e', LD, and lower levels of MPI). The findings remained with statistical significance after adjustment for sex, ischemic heart disease, diabetes, hypertension, and body mass index (e' = 11.0, 95% CI (10.4-11.6), p < 0.001; LD = 12.8 (12.3-13.4), p < 0.003; MPI: 0.40 (0.38-0.42), p = 0.02). In age > 65 years, there was a tendency of impaired cardiac function in higher levels of exercise. Interaction analysis revealed that age significantly modified the association between physical activity and cardiac function (p < 0.001). We found a positive association between higher level of physical activity and improved cardiac function in younger persons (< 50 years). In the general population, however, the association interacted with age and amongst persons above 65 years there was a negative association between higher level of physical activity and cardiac function.

Role of matrix metalloproteinases and histone deacetylase in oxidative stress-induced degradation of the endothelial glycocalyx

The glycocalyx is crucial for normal endothelial function. It also tethers extracellular superoxide dismutase (SOD3), which protects the endothelium against oxidative damage. Proteolytic enzymes [matrix metalloproteinases (MMPs)] are capable of disrupting endothelial cell surface proteins, such as syndecans, resulting in derangements of the endothelial glycocalyx. We sought to test the role of MMPs in oxidative stress-mediated disruption of the endothelial glycocalyx and examine the effect of pharmacological inhibition of MMPs on mitigating this detrimental effect. We also examined the role of histone deacetylase (HDAC) in the oxidative stress-mediated MMP induction and glycocalyx remodeling. Oxidative stress was experimentally induced in human adipose microvascular endothelial cells using H₂O₂ and buthionine sulfoximine in the presence and absence of potent MMP and HDAC inhibitors. H₂O₂ and buthionine sulfoximine resulted in a notable loss of the endothelial glycocalyx; they also increased the expression and proteolytic activity of MMP-2 and MMP-9 and subsequently increased the shedding of syndecan-1 and SOD3 from the endothelial cell surface. MMP upregulation was accompanied by a decline in mRNA and protein levels of their inhibitors, tissue inhibitors of metalloproteinase (TIMPs; TIMP-1 and TIMP-3). Furthermore, oxidative stress induced HDAC activity. Inhibition of MMPs and HDAC reversed syndecan-1 and SOD3 shedding and maintained endothelial glycocalyx integrity. HDAC inhibition increased TIMP expression and reduced MMP expression and activity in endothelial cells. Our findings shed light on MMPs and HDAC as therapeutically targetable mechanisms in oxidative stress-induced glycocalyx remodeling. NEW & NOTEWORTHY Oxidative stress, a hallmark of many diseases, damages the endothelial glycocalyx, resulting in vascular dysfunction. Studying the mechanistic link between oxidative stress and endothelial glycocalyx derangements might help discover new therapeutic targets to preserve vascular function. In this study, we investigated the involvement of matrix metalloproteinases and histone deacetylase in oxidative stress-induced endothelial glycocalyx degradation.

Protective role of Gentianella acuta on isoprenaline induced myocardial fibrosis in rats via inhibition of NF-κB pathway

Gentianella acuta (Michx.) Hulten (G. acuta) has been widely used in Mongolian medicines for the treatment of cardiovascular diseases in Ewenki and Oroqen, Inner Mongolia autonomous region, China. The aim of this study was to investigate the effects and related mechanism of G. acuta on isoproterenol (ISO)-induced oxidative stress, fibrosis, and myocardial damage in rats. Male Sprague Dawley rats were randomly divided into the normal control group, ISO induced group and ISO+G. acuta treatment group. Rats were administered with ISO subcutaneously (5 mg/kg/day) for 7 days, and were orally administered simultaneously with aqueous extracts of G. acuta for 21 days. This investigation showed G. acuta treatment ameliorated cardiac structural disorder, excessive collagenous fiber accumulation and cardiac malfunction. Compared with the ISO induced model group, G. acuta treatment increased superoxide dismutase (SOD) activities and glutathione (GSH) level, prevented the rise of malondialdehyde (MDA), and decreased hydroxyproline contents in the heart tissues. Moreover, G. acuta reduced the expression of transforming growth factor β1 (TGF-β1) and connective tissue growth factor (CTGF), and inhibited the expression and activation of NF-κB-P65 in myocardial tissues. These results suggested that G. acuta protects against ISO-induced cardiac malfunction probably by preventing oxidative stress, and fibrosis, and the mechanism might be through inhibiting NF-κB pathway.

Risk Stratification of Sudden Cardiac Death in Patients with Heart Failure: An update

Heart failure (HF) is a complex clinical syndrome in which structural/functional myocardial abnormalities result in symptoms and signs of hypoperfusion and/or pulmonary or systemic congestion at rest or during exercise. More than 80% of deaths in patients with HF recognize a cardiovascular cause, with most being either sudden cardiac death (SCD) or death caused by progressive pump failure. Risk stratification of SCD in patients with HF and preserved (HFpEF) or reduced ejection fraction (HFrEF) represents a clinical challenge. This review will give an update of current strategies for SCD risk stratification in both HFrEF and HFpEF.

Antimalarial-induced Cardiomyopathy in Systemic Lupus Erythematosus: As Rare as Considered?

OBJECTIVE

Antimalarials (AM) are recommended for all systemic lupus erythematosus (SLE) patients without specific contraindications. Their main adverse effect is retinal damage; however, heart disease has been described in isolated cases. The aim of our study is to describe 8 patients with AM-induced cardiomyopathy (AMIC) in a defined SLE cohort.

METHODS

Patients attending the Toronto Lupus Clinic and diagnosed with definite (based on endomyocardial biopsy; EMB) and possible AMIC were included [based on cardiac magnetic resonance imaging (cMRI) and other investigations].

RESULTS

Eight female patients (median age 62.5 yrs, disease duration 35 yrs, AM use duration 22 yrs) were diagnosed with AMIC in the past 2 years. Diagnosis was based on EMB in 3 (extensive cardiomyocyte vacuolation, intracytoplasmic myelinoid, and curvilinear bodies). In 4 patients, cMRI was highly suggestive of AMIC (ventricular hypertrophy and/or atrial enlargement and late gadolinium enhancement in a nonvascular pattern). Another patient was diagnosed with complete atrioventricular block, left ventricular and septal hypertrophy, along with concomitant ocular toxicity. All patients had abnormal cardiac troponin I (cTnI) and brain natriuretic peptide (BNP), whereas 7/8 also had chronically elevated creatine phosphokinase. During followup, 1 patient died from refractory heart failure. In the remaining patients, hypertrophy regression and a steady decrease of heart biomarkers were observed after AM cessation.

CONCLUSION

Once considered extremely rare, AMIC seems to be underrecognized, probably because of the false attribution of heart failure or hypertrophy to other causes. Certain biomarkers (cTnI, BNP) and imaging findings may lead to early diagnosis and enhance survival.

Extracellular matrix remodeling and cardiac fibrosis

Cardiac fibrosis, characterized by excessive deposition of extracellular matrix (ECM) proteins in the myocardium, distorts the architecture of the myocardium, facilitates the progression of arrhythmia and cardiac dysfunction, and influences the clinical course and outcome in patients with heart failure. This review describes the composition and homeostasis in normal cardiac interstitial matrix and introduces cellular and molecular mechanisms involved in cardiac fibrosis. We also characterize the ECM alteration in the fibrotic response under diverse cardiac pathological conditions and depict the role of matricellular proteins in the pathogenesis of cardiac fibrosis. Moreover, the diagnosis of cardiac fibrosis based on imaging and biomarker detection and the therapeutic strategies are addressed. Understanding the comprehensive molecules and pathways involved in ECM homeostasis and remodeling may provide important novel potential targets for preventing and treating cardiac fibrosis.

Complement 5a Receptor deficiency does not influence adverse cardiac remodeling after pressure-overload in mice

Hypertension is one of the most common risk factors for the development heart failure in the general population. Inflammation plays a central role in this adverse remodeling and eventually to the development of heart failure. Circulating levels of Complement factor 5a (C5a) are increased in hypertensive patients and the C5a receptor is associated with the presence of cardiac fibrosis and inflammation in an experimental hypertension model. To test if C5aR is involved in adverse cardiac remodeling following pressure-overload, we induced transverse aortic constriction (TAC) in wildtype and C5a receptor deficient mice (C5aR^-/-). Six weeks after TAC, C5aR-/- animals showed a similar degree of cardiac hypertrophy and decrease in cardiac function as wild type mice (End Systolic Volume; 50.30±5.32 µl vs. 55.81±8.16 µl). In addition, other features of adverse cardiac remodeling like cardiomyocyte cell size (WGA staining), fibrosis (picrosirius red staining) or collagen degradation (matrix metalloproteinase activity assay) did not differ either. In conclusion, full body C5aR deficiency does not affect adverse cardiac remodeling after pressure-overload. However, our finding are in contrast with C5a inhibition studies. Our observations do present the role of C5a-C5aR in adverse cardiac remodeling and heart failure as controversial at the least.