Follistatin-like 3 mediates paracrine fibroblast activation by cardiomyocytes

Large scale plasma proteomics identifies novel proteins and protein networks associated with heart failure development

Heart failure (HF) causes substantial morbidity and mortality but its pathobiology is incompletely understood. The proteome is a promising intermediate phenotype for discovery of novel mechanisms. We measured 4877 plasma proteins in 13,900 HF-free individuals across three analysis sets with diverse age, geography, and HF ascertainment to identify circulating proteins and protein networks associated with HF development. Parallel analyses in Atherosclerosis Risk in Communities study participants in mid-life and late-life and in Trøndelag Health Study participants identified 37 proteins consistently associated with incident HF independent of traditional risk factors. Mendelian randomization supported causal effects of 10 on HF, HF risk factors, or left ventricular size and function, including matricellular (e.g. SPON1, MFAP4), senescence-associated (FSTL3, IGFBP7), and inflammatory (SVEP1, CCL15, ITIH3) proteins. Protein co-regulation network analyses identified 5 modules associated with HF risk, two of which were influenced by genetic variants that implicated trans hotspots within the VTN and CFH genes.

Follistatin-like 1 and its paralogs in heart development and cardiovascular disease

Cardiovascular diseases (CVDs) are a group of disorders affecting the heart and blood vessels and a leading cause of death worldwide. Thus, there is a need to identify new cardiokines that may protect the heart from damage as reported in GBD 2017 Causes of Death Collaborators (2018) (The Lancet 392:1736-1788). Follistatin-like 1 (FSTL1) is a cardiokine that is highly expressed in the heart and released to the serum after cardiac injury where it is associated with CVD and predicts poor outcome. The action of FSTL1 likely depends not only on the tissue source but also post-translation modifications that are target tissue- and cell-specific. Animal studies examining the effect of FSTL1 in various models of heart disease have exploded over the past 15 years and primarily report a protective effect spanning from inhibiting inflammation via transforming growth factor, preventing remodeling and fibrosis to promoting angiogenesis and hypertrophy. A better understanding of FSTL1 and its homologs is needed to determine whether this protein could be a useful novel biomarker to predict poor outcome and death and whether it has therapeutic potential. The aim of this review is to provide a comprehensive description of the literature for this family of proteins in order to better understand their role in normal physiology and CVD.

Roles of follistatin-like protein 3 in human non-tumor pathophysiologies and cancers

Follistatin-like protein 3 (FSTL3) is a type of FSTLs. By interacting with a disintegrin and metalloproteinase 12 (ADAM12), transforming growth factor-β ligands (activin, myostatin and growth differentiation factor (GDF) 11), FSTL3 can either activate or inhibit these molecules in human non-tumor pathophysiologies and cancers. The FSTL3 gene was initially discovered in patients with in B-cell chronic lymphocytic leukemia, and subsequent studies have shown that the FSTL3 protein is associated with reproductive development, insulin resistance, and hematopoiesis. FSTL3 reportedly contributes to the development and progression of many cancers by promoting tumor metastasis, facilitating angiogenesis, and inducing stem cell differentiation. This review summarizes the current pathophysiological roles of FSTL3, which may be a putative prognostic biomarker for various diseases and serve as a potential therapeutic target.

Genome-wide transcriptome profiling of human trabecular meshwork cells treated with TGF-β2

Glaucoma is a complex neurodegenerative disease resulting in progressive optic neuropathy and is a leading cause of irreversible blindness worldwide. Primary open angle glaucoma (POAG) is the predominant form affecting 65.5 million people globally. Despite the prevalence of POAG and the identification of over 120 glaucoma related genetic loci, the underlaying molecular mechanisms are still poorly understood. The transforming growth factor beta (TGF-β) signalling pathway is implicated in the molecular pathology of POAG. To gain a better understanding of the role TGF-β2 plays in the glaucomatous changes to the molecular pathology in the trabecular meshwork, we employed RNA-Seq to delineate the TGF-β2 induced changes in the transcriptome of normal primary human trabecular meshwork cells (HTM). We identified a significant number of differentially expressed genes and associated pathways that contribute to the pathogenesis of POAG. The differentially expressed genes were predominantly enriched in ECM regulation, TGF-β signalling, proliferation/apoptosis, inflammation/wound healing, MAPK signalling, oxidative stress and RHO signalling. Canonical pathway analysis confirmed the enrichment of RhoA signalling, inflammatory-related processes, ECM and cytoskeletal organisation in HTM cells in response to TGF-β2. We also identified novel genes and pathways that were affected after TGF-β2 treatment in the HTM, suggesting additional pathways are activated, including Nrf2, PI3K-Akt, MAPK and HIPPO signalling pathways. The identification and characterisation of TGF-β2 dependent differentially expressed genes and pathways in HTM cells is essential to understand the patho-physiology of glaucoma and to develop new therapeutic agents.

Follistatin-Like Proteins: Structure, Functions and Biomedical Importance

Main forms of cellular signal transmission are known to be autocrine and paracrine signaling. Several cells secrete messengers called autocrine or paracrine agents that can bind the corresponding receptors on the surface of the cells themselves or their microenvironment. Follistatin and follistatin-like proteins can be called one of the most important bifunctional messengers capable of displaying both autocrine and paracrine activity. Whilst they are not as diverse as protein hormones or protein kinases, there are only five types of proteins. However, unlike protein kinases, there are no minor proteins among them; each follistatin-like protein performs an important physiological function. These proteins are involved in a variety of signaling pathways and biological processes, having the ability to bind to receptors such as DIP2A, TLR4, BMP and some others. The activation or experimentally induced knockout of the protein-coding genes often leads to fatal consequences for individual cells and the whole body as follistatin-like proteins indirectly regulate the cell cycle, tissue differentiation, metabolic pathways, and participate in the transmission chains of the pro-inflammatory intracellular signal. Abnormal course of these processes can cause the development of oncology or apoptosis, programmed cell death. There is still no comprehensive understanding of the spectrum of mechanisms of action of follistatin-like proteins, so the systematization and study of their cellular functions and regulation is an important direction of modern molecular and cell biology. Therefore, this review focuses on follistatin-related proteins that affect multiple targets and have direct or indirect effects on cellular signaling pathways, as well as to characterize the directions of their practical application in the field of biomedicine.

Cardiac fibrosis

Myocardial fibrosis, the expansion of the cardiac interstitium through deposition of extracellular matrix proteins, is a common pathophysiologic companion of many different myocardial conditions. Fibrosis may reflect activation of reparative or maladaptive processes. Activated fibroblasts and myofibroblasts are the central cellular effectors in cardiac fibrosis, serving as the main source of matrix proteins. Immune cells, vascular cells and cardiomyocytes may also acquire a fibrogenic phenotype under conditions of stress, activating fibroblast populations. Fibrogenic growth factors (such as transforming growth factor-β and platelet-derived growth factors), cytokines [including tumour necrosis factor-α, interleukin (IL)-1, IL-6, IL-10, and IL-4], and neurohumoral pathways trigger fibrogenic signalling cascades through binding to surface receptors, and activation of downstream signalling cascades. In addition, matricellular macromolecules are deposited in the remodelling myocardium and regulate matrix assembly, while modulating signal transduction cascades and protease or growth factor activity. Cardiac fibroblasts can also sense mechanical stress through mechanosensitive receptors, ion channels and integrins, activating intracellular fibrogenic cascades that contribute to fibrosis in response to pressure overload. Although subpopulations of fibroblast-like cells may exert important protective actions in both reparative and interstitial/perivascular fibrosis, ultimately fibrotic changes perturb systolic and diastolic function, and may play an important role in the pathogenesis of arrhythmias. This review article discusses the molecular mechanisms involved in the pathogenesis of cardiac fibrosis in various myocardial diseases, including myocardial infarction, heart failure with reduced or preserved ejection fraction, genetic cardiomyopathies, and diabetic heart disease. Development of fibrosis-targeting therapies for patients with myocardial diseases will require not only understanding of the functional pluralism of cardiac fibroblasts and dissection of the molecular basis for fibrotic remodelling, but also appreciation of the pathophysiologic heterogeneity of fibrosis-associated myocardial disease.

Prioritizing Candidates of Post-Myocardial Infarction Heart Failure Using Plasma Proteomics and Single-Cell Transcriptomics

Supplemental Digital Content is available in the text.

Background:

Heart failure (HF) is the most common long-term complication of acute myocardial infarction (MI). Understanding plasma proteins associated with post-MI HF and their gene expression may identify new candidates for biomarker and drug target discovery.

Methods:

We used aptamer-based affinity-capture plasma proteomics to measure 1305 plasma proteins at 1 month post-MI in a New Zealand cohort (CDCS [Coronary Disease Cohort Study]) including 181 patients post-MI who were subsequently hospitalized for HF in comparison with 250 patients post-MI who remained event free over a median follow-up of 4.9 years. We then correlated plasma proteins with left ventricular ejection fraction measured at 4 months post-MI and identified proteins potentially coregulated in post-MI HF using weighted gene co-expression network analysis. A Singapore cohort (IMMACULATE [Improving Outcomes in Myocardial Infarction through Reversal of Cardiac Remodelling]) of 223 patients post-MI, of which 33 patients were hospitalized for HF (median follow-up, 2.0 years), was used for further candidate enrichment of plasma proteins by using Fisher meta-analysis, resampling-based statistical testing, and machine learning. We then cross-referenced differentially expressed proteins with their differentially expressed genes from single-cell transcriptomes of nonmyocyte cardiac cells isolated from a murine MI model, and single-cell and single-nucleus transcriptomes of cardiac myocytes from murine HF models and human patients with HF.

Results:

In the CDCS cohort, 212 differentially expressed plasma proteins were significantly associated with subsequent HF events. Of these, 96 correlated with left ventricular ejection fraction measured at 4 months post-MI. Weighted gene co-expression network analysis prioritized 63 of the 212 proteins that demonstrated significantly higher correlations among patients who developed post-MI HF in comparison with event-free controls (data set 1). Cross-cohort meta-analysis of the IMMACULATE cohort identified 36 plasma proteins associated with post-MI HF (data set 2), whereas single-cell transcriptomes identified 15 gene-protein candidates (data set 3). The majority of prioritized proteins were of matricellular origin. The 6 most highly enriched proteins that were common to all 3 data sets included well-established biomarkers of post-MI HF: N-terminal B-type natriuretic peptide and troponin T, and newly emergent biomarkers, angiopoietin-2, thrombospondin-2, latent transforming growth factor-β binding protein-4, and follistatin-related protein-3, as well.

Conclusions:

Large-scale human plasma proteomics, cross-referenced to unbiased cardiac transcriptomics at single-cell resolution, prioritized protein candidates associated with post-MI HF for further mechanistic and clinical validation.

Galectin-3 Is Associated With Stage B Metabolic Heart Disease and Pulmonary Hypertension in Young Obese Patients

Background

Obesity is a precursor to heart failure with preserved ejection fraction. Biomarkers that identify preclinical metabolic heart disease (MHD) in young obese patients would help identify high‐risk individuals for heart failure prevention strategies. We assessed the predictive value of GAL3 (galectin–3), FSTL3 (follistatin‐like 3 peptide), and NT‐proBNP (N‐terminal pro‐B‐type natriuretic peptide) to identify stage B MHD in young obese participants free of clinically evident cardiovascular disease.

Methods and Results

Asymptomatic obese patients (n=250) and non‐obese controls (n=21) underwent echocardiographic cardiac phenotyping. Obese patients were classified as MHD positive (MHD‐POS; n=94) if they had abnormal diastolic function or left ventricular hypertrophy and had estimated pulmonary artery systolic pressure ≥35 mm Hg. Obese patients without such abnormalities were classified as MHD negative (MHD‐NEG; n=52). Serum biomarkers timed with echocardiography. MHD‐POS and MHD‐NEG individuals were similarly obese, but MHD‐POS patients were older, with more diabetes mellitus and metabolic syndrome. Right ventricular coupling was worse in MHD‐POS patients (P<0.001). GAL3 levels were higher in MHD‐POS versus MHD‐NEG patients (7.7±2.3 versus 6.3±1.9 ng/mL, respectively; P<0.001). Both GAL3 and FSTL3 levels correlated with diastolic dysfunction and increased pulmonary artery systolic pressure but not with left ventricular mass. In multivariate models including all 3 biomarkers, only GAL3 remained associated with MHD (odds ratio: 1.30; 95% CI, 1.01–1.68; P=0.04).

Conclusions

In young obese individuals without known cardiovascular disease, GAL3 is associated with the presence of preclinical MHD. GAL3 may be useful in screening for preclinical MHD and identifying individuals with increased risk of progression to obesity‐related heart failure with preserved ejection fraction.

The Role of the TGF-β Superfamily in Myocardial Infarction

The members of the transforming growth factor β (TGF-β) superfamily are essential regulators of cell differentiation, phenotype and function, and have been implicated in the pathogenesis of many diseases. Myocardial infarction is associated with induction of several members of the superfamily, including TGF-β1, TGF-β2, TGF-β3, bone morphogenetic protein (BMP)-2, BMP-4, BMP-10, growth differentiation factor (GDF)-8, GDF-11 and activin A. This manuscript reviews our current knowledge on the patterns and mechanisms of regulation and activation of TGF-β superfamily members in the infarcted heart, and discusses their cellular actions and downstream signaling mechanisms. In the infarcted heart, TGF-β isoforms modulate cardiomyocyte survival and hypertrophic responses, critically regulate immune cell function, activate fibroblasts, and stimulate a matrix-preserving program. BMP subfamily members have been suggested to exert both pro- and anti-inflammatory actions and may regulate fibrosis. Members of the GDF subfamily may also modulate survival and hypertrophy of cardiomyocytes and regulate inflammation. Important actions of TGF-β superfamily members may be mediated through activation of Smad-dependent or non-Smad pathways. The critical role of TGF-β signaling cascades in cardiac repair, remodeling, fibrosis, and regeneration may suggest attractive therapeutic targets for myocardial infarction patients. However, the pleiotropic, cell-specific, and context-dependent actions of TGF-β superfamily members pose major challenges in therapeutic translation.

Gene structure, recombinant expression and function characterization of Siniperca chuatsi Fsrp-3

A full-length complementary (c)DNA sequence encoding follistatin-related protein 3 (fsrp-3) was determined from skeletal muscle in Chinese mandarin fish Siniperca chuatsi, its molecular structure was characterised and its function suggested. The putative structure of S. chuatsi Fsrp-3 contains an N-terminal domain and two follistatin domains. Quantitative reverse-transcription (qRT)-PCR assays revealed that fsrp-3 messenger (m)RNA was differentially expressed among assayed tissues and was highly expressed in heart and intestine. fsrp-3 mRNA exhibited increasing expression from the larval to the juvenile stage (500 g). To investigate the potential function of S. chuatsi fsrp-3 in muscle growth, we constructed a Fsrp-3 prokaryotic expression system and injected the purified Fsrp-3 fusion protein into the dorsal muscle. Fsrp-3 administration significantly influenced cross-section area, satellite cell activation frequency and nuclear density of S. chuatsi muscle fibres. Following Fsrp-3 treatment, the expression of myogenic regulatory factors was up-regulated and decline in the expression of myostatin was observed. The study revealed that Fsrp-3 may affect muscle growth by regulating myogenic regulatory factor expression and antagonizing myostatin function to initiate satellite cell activation and differentiation in S. chuatsi.

Cardiac fibrosis: Cell biological mechanisms, molecular pathways and therapeutic opportunities

Cardiac fibrosis is a common pathophysiologic companion of most myocardial diseases, and is associated with systolic and diastolic dysfunction, arrhythmogenesis, and adverse outcome. Because the adult mammalian heart has negligible regenerative capacity, death of a large number of cardiomyocytes results in reparative fibrosis, a process that is critical for preservation of the structural integrity of the infarcted ventricle. On the other hand, pathophysiologic stimuli, such as pressure overload, volume overload, metabolic dysfunction, and aging may cause interstitial and perivascular fibrosis in the absence of infarction. Activated myofibroblasts are the main effector cells in cardiac fibrosis; their expansion following myocardial injury is primarily driven through activation of resident interstitial cell populations. Several other cell types, including cardiomyocytes, endothelial cells, pericytes, macrophages, lymphocytes and mast cells may contribute to the fibrotic process, by producing proteases that participate in matrix metabolism, by secreting fibrogenic mediators and matricellular proteins, or by exerting contact-dependent actions on fibroblast phenotype. The mechanisms of induction of fibrogenic signals are dependent on the type of primary myocardial injury. Activation of neurohumoral pathways stimulates fibroblasts both directly, and through effects on immune cell populations. Cytokines and growth factors, such as Tumor Necrosis Factor-α, Interleukin (IL)-1, IL-10, chemokines, members of the Transforming Growth Factor-β family, IL-11, and Platelet-Derived Growth Factors are secreted in the cardiac interstitium and play distinct roles in activating specific aspects of the fibrotic response. Secreted fibrogenic mediators and matricellular proteins bind to cell surface receptors in fibroblasts, such as cytokine receptors, integrins, syndecans and CD44, and transduce intracellular signaling cascades that regulate genes involved in synthesis, processing and metabolism of the extracellular matrix. Endogenous pathways involved in negative regulation of fibrosis are critical for cardiac repair and may protect the myocardium from excessive fibrogenic responses. Due to the reparative nature of many forms of cardiac fibrosis, targeting fibrotic remodeling following myocardial injury poses major challenges. Development of effective therapies will require careful dissection of the cell biological mechanisms, study of the functional consequences of fibrotic changes on the myocardium, and identification of heart failure patient subsets with overactive fibrotic responses.

The Role of Cardiokines in Heart Diseases: Beneficial or Detrimental?

Cardiovascular disease remains the leading cause of morbidity and mortality, imposing a major disease burden worldwide. Therefore, there is an urgent need to identify new therapeutic targets. Recently, the concept that the heart acts as a secretory organ has attracted increasing attention. Proteins secreted by the heart are called cardiokines, and they play a critical physiological role in maintaining heart homeostasis or responding to myocardial damage and thereby influence the development of heart diseases. Given the critical role of cardiokines in heart disease, they might represent a promising therapeutic target. This review will focus on several cardiokines and discuss their roles in the pathogenesis of heart diseases and as potential therapeutics.

Modeling Human Cardiac Hypertrophy in Stem Cell-Derived Cardiomyocytes

Cardiac hypertrophy accompanies many forms of cardiovascular diseases. The mechanisms behind the development and regulation of cardiac hypertrophy in the human setting are poorly understood, which can be partially attributed to the lack of a human cardiomyocyte-based preclinical test system recapitulating features of diseased myocardium. The objective of our study is to determine whether human embryonic stem cell-derived cardiomyocytes (hESC-CMs) subjected to mechanical stretch can be used as an adequate in vitro model for studying molecular mechanisms of cardiac hypertrophy. We show that hESC-CMs subjected to cyclic stretch, which mimics mechanical overload, exhibit essential features of a hypertrophic state on structural, functional, and gene expression levels. The presented hESC-CM stretch approach provides insight into molecular mechanisms behind mechanotransduction and cardiac hypertrophy and lays groundwork for the development of pharmacological approaches as well as for discovering potential circulating biomarkers of cardiac dysfunction.

Prokineticin receptor-1-dependent paracrine and autocrine pathways control cardiac tcf21+ fibroblast progenitor cell transformation into adipocytes and vascular cells

Cardiac fat tissue volume and vascular dysfunction are strongly associated, accounting for overall body mass. Despite its pathophysiological significance, the origin and autocrine/paracrine pathways that regulate cardiac fat tissue and vascular network formation are unclear. We hypothesize that adipocytes and vasculogenic cells in adult mice hearts may share a common cardiac cells that could transform into adipocytes or vascular lineages, depending on the paracrine and autocrine stimuli. In this study utilizing transgenic mice overexpressing prokineticin receptor (PKR1) in cardiomyocytes, and tcf21ERT-cre^TM-derived cardiac fibroblast progenitor (CFP)-specific PKR1 knockout mice (PKR1^tcf−/−), as well as FACS-isolated CFPs, we showed that adipogenesis and vasculogenesis share a common CFPs originating from the tcf21⁺ epithelial lineage. We found that prokineticin-2 is a cardiomyocyte secretome that controls CFP transformation into adipocytes and vasculogenic cells in vivo and in vitro. Upon HFD exposure, PKR1^tcf−/− mice displayed excessive fat deposition in the atrioventricular groove, perivascular area, and pericardium, which was accompanied by an impaired vascular network and cardiac dysfunction. This study contributes to the cardio-obesity field by demonstrating that PKR1 via autocrine/paracrine pathways controls CFP–vasculogenic- and CFP-adipocyte-transformation in adult heart. Our study may open up new possibilities for the treatment of metabolic cardiac diseases and atherosclerosis.

Circulating irisin levels are lower in patients with either stable coronary artery disease (CAD) or myocardial infarction (MI) versus healthy controls, whereas follistatin and activin A levels are higher and can discriminate MI from CAD with similar to CK-MB accuracy

BACKGROUND

Several myokines are produced by cardiac muscle. We investigated changes in myokine levels at the time of acute myocardial infarction (MI) and following reperfusion in relation to controls.

METHODS

Patients with MI (MI Group, n=31) treated with percutaneous coronary intervention (PCI) were compared to patients with stable coronary artery disease (CAD) subjected to scheduled PCI (CAD Group, n=40) and controls with symptoms mimicking CAD without stenosis in angiography (Control Group, n=43). The number and degree of stenosis were recorded. Irisin, follistatin, follistatin-like 3, activin A and B, ALT, AST, CK and CK-MB were measured at baseline and 6 or 24h after the intervention.

RESULTS

MI and CAD patients had lower irisin than controls (p<0.001). MI patients had higher follistatin, activin A, CK, CK-MB and AST than CAD patients and controls (all p≤0.001). None of the myokines changed following reperfusion. Circulating irisin was associated with the degree of stenosis in all patients (p=0.05). Irisin was not inferior to CK-MB in predicting MI while folistatin and activin A could discriminate MI from CAD patients with similar to CK-MB accuracy. None of these myokines was altered following PCI in contrast to CK-MB.

CONCLUSIONS

Irisin levels are lower in MI and CAD implying that their production may depend on myocadial blood supply. Follistatin and activin A are higher in MI than in CAD suggesting increased release due to myocardial necrosis. They can predict MI with accuracy similar to CK-MB and their role in the diagnosis of MI remains to be confirmed by prospective large clinical studies.

Histone Deacetylase 5 Is Overexpressed in Scleroderma Endothelial Cells and Impairs Angiogenesis via Repression of Proangiogenic Factors

OBJECTIVE

Vascular dysfunction represents a disease-initiating event in systemic sclerosis (SSc; scleroderma). Results of recent studies suggest that epigenetic dysregulation impairs normal angiogenesis and can result in abnormal patterns of blood vessel growth. Histone deacetylases (HDACs) control endothelial cell (EC) proliferation and regulate EC migration. Specifically, HDAC-5 appears to be antiangiogenic. This study was undertaken to test whether HDAC-5 contributes to impaired angiogenesis in SSc by repressing proangiogenic factors in ECs.

METHODS

Dermal ECs were isolated from patients with diffuse cutaneous SSc and healthy controls. Angiogenesis was assessed using an in vitro Matrigel tube formation assay. An assay for transposase-accessible chromatin using sequencing (ATAC-seq) was performed to assess and localize the genome-wide effects of HDAC5 knockdown on chromatin accessibility.

RESULTS

The expression of HDAC5 was significantly increased in ECs from patients with SSc compared to healthy control ECs. Silencing of HDAC5 in SSc ECs restored normal angiogenesis. HDAC5 knockdown followed by ATAC-seq assay in SSc ECs identified key HDAC5-regulated genes involved in angiogenesis and fibrosis, such as CYR61, PVRL2, and FSTL1. Simultaneous knockdown of HDAC5 in conjunction with either CYR61, PVRL2, or FSTL1 inhibited angiogenesis in SSc ECs. Conversely, overexpression of these genes individually led to an increase in tube formation as assessed by Matrigel assay, suggesting that these genes play functional roles in the impairment of angiogenesis in SSc.

CONCLUSION

Several novel HDAC5-regulated target genes associated with impaired angiogenesis were identified in SSc ECs by ATAC-seq. The results of this study provide a potential link between epigenetic regulation and impaired angiogenesis in SSc, and identify a novel mechanism for the dysregulated angiogenesis that characterizes this disease.

Luhong formula inhibits myocardial fibrosis in a paracrine manner by activating the gp130/JAK2/STAT3 pathway in cardiomyocytes

ETHNOPHARMACOLOGICAL RELEVANCE

Luhong formula (LHF)-a traditional Chinese medicine containing Cervus nippon Temminck, Carthamus tinctorius L., Cinnamomum cassia Presl, Codonopisis pilosula( Franch.) Nannf., Astragalus membranaceus ( Fisch.) Bge. var. mongholicus ( Bge.) Hsiao, Lepidium apetalum Willd-is used in the treatment of heart failure.

AIM OF THE STUDY

To investigate the antifibrotic efficacy of LHF in a myocardial infarction-induced rat model of heart failure and to determine its mechanism of action.

MATERIAL AND METHODS

Myocardial infarction was induced in rats by coronary artery ligation, and cardiac fibroblasts were isolated. Neonatal rat cardiomyocytes (NRCMs) were isolated from 2 to 3-day-old Sprague-Dawley male rats, and cardiomyocyte hypertrophy was induced by isoprenaline. Histological examination was carried out to estimate the degree of myocardial fibrosis. Expression of gp130/JAK2/STAT3 pathway proteins was measured by western blot. The mRNA levels of downstream genes of gp130/JAK2/STAT3 pathway (i.e., CTGF, TSP-1, and TIMP1) were determined by RT-PCR; while CTGF, TSP-1, and TIMP1 protein levels were measured by ELISA. To investigate paracrine effects, cell proliferation and collagen synthesis was measured after treating cardiac fibroblasts with the conditioned media from isoprenaline-treated NRCMs.

RESULTS

Histopathological changes showed that LHF inhibited myocardial fibrosis in heart failure rats. Treatment with LHF up-regulated gp130, JAK2, and STAT3 protein expression in heart tissue, and down-regulated CTGF, TSP-1, and TIMP1 gene expression. Isoprenaline-treated NRCMs displayed lower expression of the gp130, JAK2, and STAT3 pathway proteins and higher secretion of its downstream signaling molecules (CTGF, TSP-1, TIMP1). LHF inhibited cardiac fibroblast proliferation and collagen synthesis after treatment with the conditioned media from isoprenaline-treated NRCMs.

CONCLUSION

LHF treatment attenuates myocardial fibrosis in vivo. LHF inhibits cardiac fibroblasts proliferation and collagen synthesis in a paracrine manner by activating the gp130/JAK2/STAT3 pathway in cardiomyocytes, thereby inhibiting the secretion of downstream profibrogenic cytokines.

Effects of the Activin A-Follistatin System on Myocardial Cell Apoptosis through the Endoplasmic Reticulum Stress Pathway in Heart Failure

BACKGROUND

A previous study suggested that activin A inhibited myocardial cell apoptosis. This study thus aimed to explore the effects of the activin A-follistatin system on myocardial cell apoptosis in heart failure (HF) rats in order to determine whether or not the mechanism operates through the endoplasmic reticulum stress (ERS) pathway.

METHODS

Myocardial infarction (MI) by vascular deprivation was used to induce HF. The enzyme-linked immunosorbent assay was used to detect activin A, follistatin and brain natriuretic peptide (BNP) contents in serum. Immunohistochemical staining for activin A, follistatin, CCAAT-enhancer-binding protein (C/EBP) homologous protein (CHOP) and caspase-3 was performed on the myocardial tissue. The activin A-stimulated apoptosis of H9c2 cells was tested by flow cytometry. Western blot was used to detect the expression levels of activin A, follistatin and ERS-related proteins.

RESULTS

It was found that the high expression of activin A could cause activin A-follistatin system imbalance, inducing myocardial cell apoptosis via ERS in vivo. When HF developed to a certain stage, the expression of follistatin was upregulated to antagonize the expression of activin A. Activin A inhibited cardiomyocyte apoptosis with a low concentration and promoted apoptosis with a high concentration in vitro, also via ERS.

CONCLUSION

Activin A-follistatin system participated in ERS-mediated myocardial cell apoptosis in HF.

Cardiokines as Modulators of Stress-Induced Cardiac Disorders

Almost 30 years ago, the protein, atrial natriuretic peptide, was identified as a heart-secreted hormone that provides a peripheral signal from the myocardium that communicates to the rest of the organism to modify blood pressure and volume under conditions of heart failure. Since then, additional peripheral factors secreted by the heart, termed cardiokines, have been identified and shown to coordinate this interorgan cross talk. In addition to this interorgan communication, cardiokines also act in an autocrine/paracrine manner to play a role in intercellular communication within the myocardium. This review focuses on the roles of newly emerging cardiokines that are mainly increased in stress-induced cardiac diseases. The potential of these cardiokines as clinical biomarkers for diagnosis and prognosis of cardiac disorders is also discussed.

Biochemistry and Biology of GDF11 and Myostatin: Similarities, Differences, and Questions for Future Investigation

Growth differentiation factor 11 (GDF11) and myostatin (or GDF8) are closely related members of the transforming growth factor β superfamily and are often perceived to serve similar or overlapping roles. Yet, despite commonalities in protein sequence, receptor utilization and signaling, accumulating evidence suggests that these 2 ligands can have distinct functions in many situations. GDF11 is essential for mammalian development and has been suggested to regulate aging of multiple tissues, whereas myostatin is a well-described negative regulator of postnatal skeletal and cardiac muscle mass and modulates metabolic processes. In this review, we discuss the biochemical regulation of GDF11 and myostatin and their functions in the heart, skeletal muscle, and brain. We also highlight recent clinical findings with respect to a potential role for GDF11 and/or myostatin in humans with heart disease. Finally, we address key outstanding questions related to GDF11 and myostatin dynamics and signaling during development, growth, and aging.

Characteristic adaptations of the extracellular matrix in dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a relatively common heart muscle disease characterized by the dilation and thinning of the left ventricle accompanied with left ventricular systolic dysfunction. Myocardial fibrosis is a major feature in DCM and therefore it is inevitable that corresponding extracellular matrix (ECM) changes are involved in DCM onset and progression. Increasing our understanding of how ECM adaptations are involved in DCM could be important for the development of future interventions. This review article discusses the molecular adaptations in ECM composition and structure that have been reported in both animal and human studies of DCM. Furthermore, we provide a transcriptome-based catalogue of ECM genes that are associated with DCM, generated by using NCBI Gene Expression Omnibus database sets for DCM. Based on this in silico analysis, many novel ECM components involved in DCM are identified and discussed in this review. With the information gathered, we propose putative pathways of ECM adaptations in onset and progression of DCM.

Intravenous delivery of adeno-associated virus 9-encoded IGF-1Ea propeptide improves post-infarct cardiac remodelling

The insulin-like growth factor Ea propeptide (IGF-1Ea) is a powerful enhancer of cardiac muscle growth and regeneration, also blocking age-related atrophy and beneficial in multiple skeletal muscle diseases. The therapeutic potential of IGF-1Ea compared with mature IGF-1 derives from its local action in the area of synthesis. We have developed an adeno-associated virus (AAV) vector for IGF-1Ea delivery to the heart to treat mice after myocardial infarction and examine the reparative effects of local IGF-1Ea production on left ventricular remodelling. A cardiotropic AAV9 vector carrying a cardiomyocyte-specific IGF-1Ea-luciferase bi-cistronic gene expression cassette (AAV9.IGF-1Ea) was administered intravenously to infarcted mice, 5 h after ischemia followed by reperfusion (I/R), as a model of myocardial infarction. Virally encoded IGF-1Ea in the heart improved global left ventricular function and remodelling, as measured by wall motion and thickness, 28 days after delivery, with higher viral titers yielding better improvement. The present study demonstrates that single intravenous AAV9-mediated IGF-1Ea Gene Therapy represents a tissue-targeted therapeutic approach to prevent the adverse remodelling after myocardial infarct.

Constitutive Expression of a Dominant-Negative TGF-β Type II Receptor in the Posterior Left Atrium Leads to Beneficial Remodeling of Atrial Fibrillation Substrate

RATIONALE

Fibrosis is an important structural contributor to formation of atrial fibrillation (AF) substrate in heart failure. Transforming growth factor-β (TGF-β) signaling is thought to be intricately involved in creation of atrial fibrosis.

OBJECTIVE

We hypothesized that gene-based expression of dominant-negative type II TGF-β receptor (TGF-β-RII-DN) in the posterior left atrium in a canine heart failure model will sufficiently attenuate fibrosis-induced changes in atrial conduction and restitution to decrease AF. Because AF electrograms are thought to reflect AF substrate, we further hypothesized that TGF-β-RII-DN would lead to increased fractionation and decreased organization of AF electrograms.

METHODS AND RESULTS

Twenty-one dogs underwent injection+electroporation in the posterior left atrium of plasmid expressing a dominant-negative TGF-β type II receptor (pUBc-TGFβ-DN-RII; n=9) or control vector (pUBc-LacZ; n=12), followed by 3 to 4 weeks of right ventricular tachypacing (240 bpm). Compared with controls, dogs treated with pUBC-TGFβ-DN-RII demonstrated an attenuated increase in conduction inhomogeneity, flattening of restitution slope and decreased duration of induced AF, with AF electrograms being more fractionated and less organized in pUBc-TGFβ-DN-RII versus pUBc-LacZ dogs. Tissue analysis revealed a significant decrease in replacement/interstitial fibrosis, p-SMAD2/3 and p-ERK1/2.

CONCLUSIONS

Targeted gene-based reduction of TGF-β signaling in the posterior left atrium-with resulting decrease in replacement fibrosis-led to beneficial remodeling of both conduction and restitution characteristics of the posterior left atrium, translating into a decrease in AF and increased complexity of AF electrograms. In addition to providing mechanistic insights, this data may have important diagnostic and therapeutic implications for AF.

Advances in induced pluripotent stem cells, genomics, biomarkers, and antiplatelet therapy highlights of the year in JCTR 2013

The Journal provides the clinician and scientist with the latest advances in discovery research, emerging technologies, preclinical research design and testing, and clinical trials. We highlight advances in areas of induced pluripotent stem cells, genomics, biomarkers, multimodality imaging, and antiplatelet biology and therapy. The top publications are critically discussed and presented along with anatomical reviews and FDA insight to provide context.

The liver X receptor agonist AZ876 protects against pathological cardiac hypertrophy and fibrosis without lipogenic side effects

AIMS

Liver X receptors (LXRs) transcriptionally regulate inflammation, metabolism, and immunity. Synthetic LXR agonists have been evaluated for their efficacy in the cardiovascular system; however, they elicit prolipogenic side effects which substantially limit their therapeutic use. AZ876 is a novel high-affinity LXR agonist. Herein, we aimed to determine the cardioprotective potential of LXR activation with AZ876.

METHODS AND RESULTS

Cardiac hypertrophy was induced in C57Bl6/J mice via transverse aortic constriction (TAC) for 6 weeks. During this period, mice received chow supplemented or not with AZ876 (20 µmol/kg/day). In murine hearts, LXRα protein expression was up-regulated ∼7-fold in response to TAC. LXR activation with AZ876 attenuated this increase, and significantly reduced TAC-induced increases in heart weight, myocardial fibrosis, and cardiac dysfunction without affecting blood pressure. At the molecular level, AZ876 suppressed up-regulation of hypertrophy- and fibrosis-related genes, and further inhibited prohypertrophic and profibrotic transforming growth factor β (TGFβ)-Smad2/3 signalling. In isolated cardiac myocytes and fibroblasts, immunocytochemistry confirmed nuclear expression of LXRα in both these cell types. In cardiomyocytes, phenylephrine-stimulated cellular hypertrophy was significantly decreased in AZ876-treated cells. In cardiac fibroblasts, AZ876 prevented TGFβ- and angiotensin II-induced fibroblast collagen synthesis, and inhibited up-regulation of the myofibroblastic marker, α-smooth muscle actin. Plasma triglycerides and liver weight were unaltered following AZ876 treatment.

CONCLUSION

AZ876 activation of LXR protects from adverse cardiac remodelling in pathological pressure overload, independently of blood pressure. LXR may thus represent a putative molecular target for antihypertrophic and antifibrotic therapies in heart failure prevention.

Guidelines for translational research in heart failure

Heart failure (HF) remains a major cause of death and hospitalization worldwide. Despite medical advances, the prognosis of HF remains poor and new therapeutic approaches are urgently needed. The development of new therapies for HF is hindered by inappropriate or incomplete preclinical studies. In these guidelines, we present a number of recommendations to enhance similarity between HF animal models and the human condition in order to reduce the chances of failure in subsequent clinical trials. We propose different approaches to address safety as well as efficacy of new therapeutic products. We also propose that good practice rules are followed from the outset so that the chances of eventual approval by regulatory agencies increase. We hope that these guidelines will help improve the translation of results from animal models to humans and thereby contribute to more successful clinical trials and development of new therapies for HF.

Induction of the calcineurin variant CnAβ1 after myocardial infarction reduces post-infarction ventricular remodelling by promoting infarct vascularization

AIMS

Ventricular remodelling following myocardial infarction progressively leads to loss of contractile capacity and heart failure. Although calcineurin promotes maladaptive cardiac hypertrophy, we recently showed that the calcineurin splicing variant, CnAβ1, has beneficial effects on the infarcted heart. However, whether this variant limits necrosis or improves remodelling is still unknown, precluding translation to the clinical arena. Here, we explored the effects and therapeutic potential of CnAβ1 overexpression post-infarction.

METHODS AND RESULTS

Double transgenic mice with inducible cardiomyocyte-specific overexpression of CnAβ1 underwent left coronary artery ligation followed by reperfusion. Echocardiographic analysis showed depressed cardiac function in all infarcted mice 3 days post-infarction. Induction of CnAβ1 overexpression 1 week after infarction improved function and reduced ventricular dilatation. CnAβ1-overexpressing mice showed shorter, thicker scars, and reduced infarct expansion, accompanied by reduced myocardial remodelling. CnAβ1 induced vascular endothelial growth factor (VEGF) expression in cardiomyocytes, which resulted in increased infarct vascularization. This paracrine angiogenic effect of CnAβ1 was mediated by activation of the Akt/mammalian target of rapamycin pathway and VEGF.

CONCLUSIONS

Our results indicate that CnAβ1 exerts beneficial effects on the infarcted heart by promoting infarct vascularization and preventing infarct expansion. These findings emphasize the translational potential of CnAβ1 for gene-based therapies.