Increased connective tissue growth factor relative to brain natriuretic peptide as a determinant of myocardial fibrosis

Catecholamine treatment induces reversible heart injury and cardiomyocyte gene expression

BACKGROUND

Catecholamines are commonly used as therapeutic drugs in intensive care medicine to maintain sufficient organ perfusion during shock. However, excessive or sustained adrenergic activation drives detrimental cardiac remodeling and may lead to heart failure. Whether catecholamine treatment in absence of heart failure causes persistent cardiac injury, is uncertain. In this experimental study, we assessed the course of cardiac remodeling and recovery during and after prolonged catecholamine treatment and investigated the molecular mechanisms involved.

RESULTS

C57BL/6N wild-type mice were assigned to 14 days catecholamine treatment with isoprenaline and phenylephrine (IsoPE), treatment with IsoPE and subsequent recovery, or healthy control groups. IsoPE improved left ventricular contractility but caused substantial cardiac fibrosis and hypertrophy. However, after discontinuation of catecholamine treatment, these alterations were largely reversible. To uncover the molecular mechanisms involved, we performed RNA sequencing from isolated cardiomyocyte nuclei. IsoPE treatment resulted in a transient upregulation of genes related to extracellular matrix formation and transforming growth factor signaling. While components of adrenergic receptor signaling were downregulated during catecholamine treatment, we observed an upregulation of endothelin-1 and its receptors in cardiomyocytes, indicating crosstalk between both signaling pathways. To follow this finding, we treated mice with endothelin-1. Compared to IsoPE, treatment with endothelin-1 induced minor but longer lasting changes in cardiomyocyte gene expression. DNA methylation-guided analysis of enhancer regions identified immediate early transcription factors such as AP-1 family members Jun and Fos as key drivers of pathological gene expression following catecholamine treatment.

CONCLUSIONS

The results from this study show that prolonged catecholamine exposure induces adverse cardiac remodeling and gene expression before the onset of left ventricular dysfunction which has implications for clinical practice. The observed changes depend on the type of stimulus and are largely reversible after discontinuation of catecholamine treatment. Crosstalk with endothelin signaling and the downstream transcription factors identified in this study provide new opportunities for more targeted therapeutic approaches that may help to separate desired from undesired effects of catecholamine treatment.

The JMJD family of histone demethylase and their intimate links to cardiovascular disease

The incidence rate and mortality rate of cardiovascular disease rank first in the world. It is associated with various high-risk factors, and there is no single cause. Epigenetic modifications, such as DNA methylation or histone modification, actively participate in the initiation and development of cardiovascular diseases. Histone lysine methylation is a type of histone post-translational modification. The human Jumonji C domain (JMJD) protein family consists of more than 30 members. JMJD proteins participate in many key nuclear processes and play a key role in the specific regulation of gene expression, DNA damage and repair, and DNA replication. Importantly, increasing evidence shows that JMJD proteins are abnormally expressed in cardiovascular diseases, which may be a potential mechanism for the occurrence and development of these diseases. Here, we discuss the key roles of JMJD proteins in various common cardiovascular diseases. This includes histone lysine demethylase, which has been studied in depth, and less-studied JMJD members. Furthermore, we focus on the epigenetic changes induced by each JMJD member, summarize recent research progress, and evaluate their relationship with cardiovascular diseases and therapeutic potential.

The role of endothelial cell in cardiac hypertrophy: Focusing on angiogenesis and intercellular crosstalk

Cardiac hypertrophy is characterized by cardiac structural remodeling, fibrosis, microvascular rarefaction, and chronic inflammation. The heart is structurally organized by different cell types, including cardiomyocytes, fibroblasts, endothelial cells, and immune cells. These cells highly interact with each other by a number of paracrine or autocrine factors. Cell-cell communication is indispensable for cardiac development, but also plays a vital role in regulating cardiac response to damage. Although cardiomyocytes and fibroblasts are deemed as key regulators of hypertrophic stimulation, other cells, including endothelial cells, also exert important effects on cardiac hypertrophy. More particularly, endothelial cells are the most abundant cells in the heart, which make up the basic structure of blood vessels and are widespread around other cells in the heart, implicating the great and inbuilt advantage of intercellular crosstalk. Cardiac microvascular plexuses are essential for transport of liquids, nutrients, molecules and cells within the heart. Meanwhile, endothelial cell-mediated paracrine signals have multiple positive or negative influences on cardiac hypertrophy. However, a comprehensive discussion of these influences and consequences is required. This review aims to summarize the basic function of endothelial cells in angiogenesis, with an emphasis on angiogenic molecules under hypertrophic conditions. The secondary objective of the research is to fully discuss the key molecules involved in the intercellular crosstalk and the endothelial cell-mediated protective or detrimental effects on other cardiac cells. This review provides a more comprehensive understanding of the overall role of endothelial cells in cardiac hypertrophy and guides the therapeutic approaches and drug development of cardiac hypertrophy.

Targeting Myocardial Fibrosis—A Magic Pill in Cardiovascular Medicine?

Fibrosis, characterized by an excessive accumulation of extracellular matrix, has long been seen as an adaptive process that contributes to tissue healing and regeneration. More recently, however, cardiac fibrosis has been shown to be a central element in many cardiovascular diseases (CVDs), contributing to the alteration of cardiac electrical and mechanical functions in a wide range of clinical settings. This paper aims to provide a comprehensive review of cardiac fibrosis, with a focus on the main pathophysiological pathways involved in its onset and progression, its role in various cardiovascular conditions, and on the potential of currently available and emerging therapeutic strategies to counteract the development and/or progression of fibrosis in CVDs. We also emphasize a number of questions that remain to be answered, and we identify hotspots for future research.

Dapagliflozin Attenuates Myocardial Fibrosis by Inhibiting the TGF-β1/Smad Signaling Pathway in a Normoglycemic Rabbit Model of Chronic Heart Failure

Recent studies have shown that sodium-glucose cotransporter-2 (SGLT2) inhibitors play a beneficial role for normoglycemic patients with heart failure (HF). However, the underlying mechanism remains largely unexplored. In the present study, we aimed to investigate the cardioprotective effect of SGLT2 inhibitors in a normoglycemic rabbit model of chronic heart failure (CHF) and its potential mechanism was also explored. A total of 24 male New Zealand white rabbits were randomly divided into the sham group, HF group, perindopril group, and dapagliflozin (DAPA) group. The normoglycemic CHF model was established by aortic constriction for 12 weeks. In the 13th week, DAPA (1 mg/kg/day) or perindopril (0.5 mg/kg/day) was administered by oral gavage daily for 10 weeks. Both the sham group and HF group were given normal saline via gavage. After 10 weeks, the heart structure and function were evaluated by echocardiography and plasma NT-proBNP. Moreover, cardiac fibrosis was analyzed using immunohistochemistry, Masson’s trichrome staining, and Western blotting analysis. The results showed that DAPA improved the myocardial structure and function of normoglycemic CHF rabbits and ameliorated myocardial fibrosis. Further study indicated that DAPA suppressed cardiac fibrosis by inhibiting the transforming growth factor β1 (TGF-β1)/Smad signaling pathway. Collectively, our findings showed that DAPA could ameliorate cardiac fibrosis in normoglycemic CHF rabbits by inhibiting the TGF-β1/Smad signaling pathway.

Data Mining Identifies CCN2 and THBS1 as Biomarker Candidates for Cardiac Hypertrophy

Cardiac hypertrophy is a condition that may contribute to the development of heart failure. In this study, we compare the gene-expression patterns of our in vitro stem-cell-based cardiac hypertrophy model with the gene expression of biopsies collected from hypertrophic human hearts. Twenty-five differentially expressed genes (DEGs) from both groups were identified and the expression of selected corresponding secreted proteins were validated using ELISA and Western blot. Several biomarkers, including CCN2, THBS1, NPPA, and NPPB, were identified, which showed significant overexpressions in the hypertrophic samples in both the cardiac biopsies and in the endothelin-1-treated cells, both at gene and protein levels. The protein-interaction network analysis revealed CCN2 as a central node among the 25 overlapping DEGs, suggesting that this gene might play an important role in the development of cardiac hypertrophy. GO-enrichment analysis of the 25 DEGs revealed many biological processes associated with cardiac function and the development of cardiac hypertrophy. In conclusion, we identified important similarities between ET-1-stimulated human-stem-cell-derived cardiomyocytes and human hypertrophic cardiac tissue. Novel putative cardiac hypertrophy biomarkers were identified and validated on the protein level, lending support for further investigations to assess their potential for future clinical applications.

Multifunctional regulatory protein connective tissue growth factor (CTGF): A potential therapeutic target for diverse diseases

Connective tissue growth factor (CTGF), a multifunctional protein of the CCN family, regulates cell proliferation, differentiation, adhesion, and a variety of other biological processes. It is involved in the disease-related pathways such as the Hippo pathway, p53 and nuclear factor kappa-B (NF-κB) pathways and thus contributes to the developments of inflammation, fibrosis, cancer and other diseases as a downstream effector. Therefore, CTGF might be a potential therapeutic target for treating various diseases. In recent years, the research on the potential of CTGF in the treatment of diseases has also been paid more attention. Several drugs targeting CTGF (monoclonal antibodies FG3149 and FG3019) are being assessed by clinical or preclinical trials and have shown promising outcomes. In this review, the cellular events regulated by CTGF, and the relationships between CTGF and pathogenesis of diseases are systematically summarized. In addition, we highlight the current researches, focusing on the preclinical and clinical trials concerned with CTGF as the therapeutic target.

YAP mediates compensatory cardiac hypertrophy through aerobic glycolysis in response to pressure overload

The heart utilizes multiple adaptive mechanisms to maintain pump function. Compensatory cardiac hypertrophy reduces wall stress and oxygen consumption, thereby protecting the heart against acute blood pressure elevation. The nuclear effector of the Hippo pathway, Yes-associated protein 1 (YAP), is activated and mediates compensatory cardiac hypertrophy in response to acute pressure overload (PO). In this study, YAP promoted glycolysis by upregulating glucose transporter 1 (GLUT1), which in turn caused accumulation of intermediates and metabolites of the glycolytic, auxiliary, and anaplerotic pathways during acute PO. Cardiac hypertrophy was inhibited and heart failure was exacerbated in mice with YAP haploinsufficiency in the presence of acute PO. However, normalization of GLUT1 rescued the detrimental phenotype. PO induced the accumulation of glycolytic metabolites, including l-serine, l-aspartate, and malate, in a YAP-dependent manner, thereby promoting cardiac hypertrophy. YAP upregulated the GLUT1 gene through interaction with TEA domain family member 1 (TEAD1) and HIF-1α in cardiomyocytes. Thus, YAP induces compensatory cardiac hypertrophy through activation of the Warburg effect.

Communication Between Cardiomyocytes and Fibroblasts During Cardiac Ischemia/Reperfusion and Remodeling: Roles of TGF-β, CTGF, the Renin Angiotensin Axis, and Non-coding RNA Molecules

Communication between cells is a foundational concept for understanding the physiology and pathology of biological systems. Paracrine/autocrine signaling, direct cell-to-cell interplay, and extracellular matrix interactions are three types of cell communication that regulate responses to different stimuli. In the heart, cardiomyocytes, fibroblasts, and endothelial cells interact to form the cardiac tissue. Under pathological conditions, such as myocardial infarction, humoral factors released by these cells may induce tissue damage or protection, depending on the type and concentration of molecules secreted. Cardiac remodeling is also mediated by the factors secreted by cardiomyocytes and fibroblasts that are involved in the extensive reciprocal interactions between these cells. Identifying the molecules and cellular signal pathways implicated in these processes will be crucial for creating effective tissue-preserving treatments during or after reperfusion. Numerous therapies to protect cardiac tissue from reperfusion-induced injury have been explored, and ample pre-clinical research has attempted to identify drugs or techniques to mitigate cardiac damage. However, despite great success in animal models, it has not been possible to completely translate these cardioprotective effects to human applications. This review provides a current summary of the principal molecules, pathways, and mechanisms underlying cardiomyocyte and cardiac fibroblast crosstalk during ischemia/reperfusion injury. We also discuss pre-clinical molecules proposed as treatments for myocardial infarction and provide a clinical perspective on these potential therapeutic agents.

Extracellular matrix remodeling in animal models of anthracycline-induced cardiomyopathy: a meta-analysis

As in other cardiomyopathies, extracellular matrix (ECM) remodeling plays an important role in anthracycline-induced cardiomyopathy. To understand the pattern and timing of ECM remodeling pathways, we conducted a systematic review in which we describe protein and mRNA markers for ECM remodeling that are differentially expressed in the hearts of animals with anthracycline-induced cardiomyopathy. We included 68 studies in mice, rats, rabbits, and pigs with follow-up of 0.1-8.2 human equivalent years after anthracycline administration. Using meta-analysis, we found 29 proteins and 11 mRNAs that were differentially expressed in anthracycline-induced cardiomyopathy compared to controls. Collagens, matrix metalloproteinases (MMPs), inflammation markers, transforming growth factor ß signaling markers, and markers for cardiac hypertrophy were upregulated, whereas the protein kinase B (AKT) pro-survival pathway was downregulated. Their expression patterns over time from single time point studies were studied with meta-regression using human equivalent years as the time scale. Connective tissue growth factor showed an early peak in expression but remained upregulated at all studied time points. Brain natriuretic peptide (BNP) and MMP9 protein levels increased in studies with longer follow-up. Significant associations were found for higher atrial natriuretic peptide with interstitial fibrosis and for higher BNP and MMP2 protein levels with left ventricular systolic function.

Resveratrol and cardiac fibrosis prevention and treatment

Cardiovascular diseases are some of the major causes of morbidity and mortality in developed or developing countries but in developed countries as well. Cardiac fibrosis is one of the most often pathological changes of heart tissues. It occurs as a result of extracellular matrix proteins accumulation at myocardia. Cardiac fibrosis results in impaired cardiac systolic and diastolic functions and is associated with other effects. Therapies with medicines have not been sufficiently successful in treating chronic diseases such as CVD. Therefore, the interest for therapeutic potential of natural compounds and medicinal plants has increased. Plants such as grapes, berries and peanuts contain a polyphenolic compound called "resveratrol" which has been reported to have various therapeutic properties for a variety of diseases. Studies on laboratory models that show that resveratrol has beneficial effects on cardiovascular diseases including myocardial infarction, high blood pressure cardiomyopathy, thrombosis, cardiac fibrosis, and atherosclerosis. In vitro animal models using resveratrol indicated protective effects on the heart by neutralizing reactive oxygen species, preventing inflammation, increasing neoangiogenesis, dilating blood vessels, suppressing apoptosis and delaying atherosclerosis. In this review, we are presenting experimental and clinical results of studies concerning resveratrol effects on cardiac fibrosis as a CVD outcome in humans.

Aging, MicroRNAs, and Heart Failure

Aging is a major risk factor for heart failure, one of the leading causes of death in Western society. The mechanisms that underlie the different forms of heart failure have been elucidated only in part and the role of noncoding RNAs is still poorly characterized. Specifically, microRNAs (miRNAs), a class of small noncoding RNAs that can modulate gene expression at the posttranscriptional level in all cells, including myocardial and vascular cells, have been shown to play a role in heart failure with reduced ejection fraction. In contrast, miRNAs role in heart failure with preserved ejection fraction, the predominant form of heart failure in the elderly, is still unknown. In this review, we will focus on age-dependent miRNAs in heart failure and on some other conditions that are prevalent in the elderly and are frequently associated with heart failure with preserved ejection fraction.

Connective Tissue Growth Factor: From Molecular Understandings to Drug Discovery

Connective tissue growth factor (CTGF) is a key signaling and regulatory molecule involved in different biological processes, such as cell proliferation, angiogenesis, and wound healing, as well as multiple pathologies, such as tumor development and tissue fibrosis. Although the underlying mechanisms of CTGF remain incompletely understood, a commonly accepted theory is that the interactions between different protein domains in CTGF and other various regulatory proteins and ligands contribute to its variety of functions. Here, we highlight the structure of each domain of CTGF and its biology functions in physiological conditions. We further summarized main diseases that are deeply influenced by CTGF domains and the potential targets of these diseases. Finally, we address the advantages and disadvantages of current drugs targeting CTGF and provide the perspective for the drug discovery of the next generation of CTGF inhibitors based on aptamers.

Targeting JMJD3 histone demethylase mediates cardiac fibrosis and cardiac function following myocardial infarction

Myocardial fibrosis is the pathological consequence of injury-induced fibroblastto-myofibroblast transition, resulting in increased stiffness and diminished cardiac function. Histone modification has been shown to play an important role in the pathogenesis of cardiac fibrosis. Here, we identified H3K27me3 demethylase JMJD3/KDM6B promotes cardiac fibrosis via regulation of fibrogenic pathways. Using neonatal rat cardiac fibroblasts (NRCF), we show that the expression of endogenous JMJD3 is induced by angiotensin II (Ang II), while the principle extracellular matrix (ECM) such as fibronectin, CTGF, collagen I and III are increased. We find that JMJD3 inhibition markedly enhances the suppressive mark (H3K27me3) at the beta (β)-catenin promoter in activated cardiac fibroblasts, and then substantially decreases expression of fibrogenic gene. Both inhibition of β-catenin-mediated transcription with ICG-001 and genetic loss of β-catenin can prevent Ang II-induced ECM deposition. Most importantly, in vivo inhibition of JMJD3 rescues myocardial ischemia-induced cardiac fibrosis and cardiac dysfunction. Collectively, our findings are the first to report a novel role of histone demethylase JMJD3 in the pro-fibrotic cardiac fibroblast phenotype, pharmacological targeting of JMJD3 might represent a promising therapeutic approach for the treatment of human cardiac fibrosis and other fibrotic diseases.

Circulating Connective Tissue Growth Factor Is Associated with Diastolic Dysfunction in Patients with Diastolic Heart Failure

Background: Connective tissue growth factor (CTGF) and transforming growth factor β1 (TGF-β1) are emerging biomarkers for tissue fibrosis. The aim of this study was to investigate the association between circulating CTGF, TGF-β1 levels and cardiac diastolic dysfunction in patients with diastolic heart failure (DHF). Methods: Admitted subjects were screened for heart failure and those with left ventricular (LV) ejection fraction <45% were excluded. Diastolic dysfunction was defined as functional abnormalities that exist during LV relaxation and filling by echocardiographic criteria. Totally 114 patients with DHF and 72 controls were enrolled. Plasma levels of CTGF, TGF-β1, and B-type natriuretic peptide (BNP) were determined. Results: The plasma CTGF and TGF-β1 levels increased significantly in patients with DHF. Circulating CTGF and TGF-β1 levels were correlated with echocardiographic parameter E/e’ and diastolic dysfunction grading in DHF patients. In multivariate logistic analysis, CTGF was significantly associated with diastolic dysfunction (odds ratio: 1.027, p < 0.001). Plasma CTGF (AUC: 0.770 ± 0.036, p < 0.001) and CTGF/BNP (AUC: 0.839 ± 0.036, p < 0.001) showed good predictive power to the diagnosis of DHF. Conclusions: This finding suggested CTGF could be involved in the pathophysiology of diastolic heart failure and CTGF/BNP might have auxiliary diagnostic value on diastolic heart failure.

The non-steroidal mineralocorticoid receptor antagonist finerenone prevents cardiac fibrotic remodeling

Mineralocorticoid receptor (MR) overactivation promotes cardiac fibrosis. We studied the ability of the non-steroidal MR antagonist finerenone to prevent fibrotic remodeling. In neonatal rat cardiac fibroblasts, finerenone prevented aldosterone-induced nuclear MR translocation. Treatment with finerenone decreased the expression of connective tissue growth factor (CTGF) (74 ± 15% of control, p = 0.005) and prevented aldosterone-induced upregulation of CTGF and lysyl oxidase (LOX) completely. Finerenone attenuated the upregulation of transforming growth factor ß (TGF-ß), which was induced by the Rac1 GTPase activator l-buthionine sulfoximine. Transgenic mice with cardiac-specific overexpression of Rac1 (RacET) showed increased left ventricular (LV) end-diastolic (63.7 ± 8.0 vs. 93.8 ± 25.6 µl, p = 0.027) and end-systolic (28.0 ± 4.0 vs. 49.5 ± 16.7 µl, p = 0.014) volumes compared to wild-type FVBN control mice. Treatment of RacET mice with 100 ppm finerenone over 5 months prevented LV dilatation. Systolic and diastolic LV function did not differ between the three groups. RacET mice exhibited overactivation of MR and 11ß hydroxysteroid dehydrogenase type 2. Both effects were reduced by finerenone (reduction about 36%, p = 0.030, and 40%, p = 0.032, respectively). RacET mice demonstrated overexpression of TGF-ß, CTGF, LOX, osteopontin as well as collagen and myocardial fibrosis in the left ventricle. In contrast, expression of these parameters did not differ between finerenone-treated RacET and control mice. Finerenone prevented left atrial dilatation (6.4 ± 1.5 vs. 4.7 ± 1.4 mg, p = 0.004) and left atrial fibrosis (17.8 ± 3.1 vs. 12.8 ± 3.1%, p = 0.046) compared to vehicle-treated RacET mice. In summary, finerenone prevented from MR-mediated structural remodeling in cardiac fibroblasts and in RacET mice. These data demonstrate anti-fibrotic myocardial effects of finerenone.

Adipose Tissue CTGF Expression is Associated with Adiposity and Insulin Resistance in Humans

OBJECTIVE

Connective tissue growth factor (CTGF) is an important regulator of fibrogenesis in many organs. This study evaluated the interrelationship among adipose tissue CTGF expression, fat mass, and insulin resistance in humans.

METHODS

This study examined (1) CTGF gene expression in human subcutaneous preadipocytes before and after inducing adipogenesis; (2) relationships among abdominal subcutaneous adipose tissue CTGF gene expression, body fat mass, and indices of insulin sensitivity, including the hepatic insulin sensitivity index and the hyperinsulinemic-euglycemic clamp procedure in conjunction with stable isotope glucose tracer infusion, in 72 people who had marked differences in adiposity and insulin sensitivity; (3) localization of CTGF protein in subcutaneous adipose tissue; and (4) effect of progressive (5%, 11%, and 16%) weight loss on adipose tissue CTGF gene expression.

RESULTS

CTGF was highly expressed in preadipocytes, not adipocytes. Adipose tissue CTGF expression was strongly correlated with body fat mass and both skeletal muscle and liver insulin sensitivity, and CTGF-positive cells were predominantly found in areas of fibrosis. Progressive weight loss caused a stepwise decrease in adipose tissue CTGF expression.

CONCLUSIONS

It was concluded that increased CTGF expression is associated with adipose tissue expansion, adipose tissue fibrosis, and multi-organ insulin resistance in people with obesity.

Connective Tissue Growth Factor Is Related to All-cause Mortality in Hemodialysis Patients and Is Lowered by On-line Hemodiafiltration: Results from the Convective Transport Study

Connective tissue growth factor (CTGF) plays a key role in the pathogenesis of tissue fibrosis. The aminoterminal fragment of CTGF is a middle molecule that accumulates in chronic kidney disease. The aims of this study are to explore determinants of plasma CTGF in hemodialysis (HD) patients, investigate whether CTGF relates to all-cause mortality in HD patients, and investigate whether online-hemodiafiltration (HDF) lowers CTGF. Data from 404 patients participating in the CONvective TRAnsport STudy (CONTRAST) were analyzed. Patients were randomized to low-flux HD or HDF. Pre-dialysis CTGF was measured by sandwich ELISA at baseline, after six and 12 months. CTGF was inversely related in multivariable analysis to glomerular filtration rate (GFR) (p < 0.001) and positively to cardiovascular disease (CVD) (p = 0.006), dialysis vintage (p < 0.001), interleukin-6 (p < 0.001), beta-2-microglobulin (p = 0.045), polycystic kidney disease (p < 0.001), tubulointerstitial nephritis (p = 0.002), and renal vascular disease (p = 0.041). Patients in the highest quartile had a higher mortality risk compared to those in the lowest quartile (HR 1.7, 95% CI: 1.02-2.88, p = 0.043). HDF lowered CTGF with 4.8% between baseline and six months, whereas during HD, CTGF increased with 4.9% (p < 0.001). In conclusion, in HD patients, CTGF is related to GFR, CVD and underlying renal disease and increased the risk of all-cause mortality. HDF reduces CTGF.

Involvement of lncR-30245 in Myocardial Infarction-Induced Cardiac Fibrosis Through Peroxisome Proliferator-Activated Receptor-γ-Mediated Connective Tissue Growth Factor Signalling Pathway

BACKGROUND

Long noncoding RNAs (lncRNAs) are emerging as important mediators of cardiac pathophysiology. The aim of the present study is to investigate the effects of lncR-30245, an lncRNA, on cardiac fibrogenesis and the underlying mechanism.

METHODS

Myocardial infarction (MI) and transforming growth factor (TGF)-β1 were used to induce fibrotic phenotypes. Cardiac fibrosis was detected by Masson's trichrome staining. Cardiac function was evaluated by echocardiography. Western blot, quantitative reverse transcription-polymerase chain reaction, and pharmacological approaches were used to investigate the role of lncR-30245 in cardiac fibrogenesis.

RESULTS

Expression of lncR-30245 was significantly increased in MI hearts and TGF-β1-treated cardiac fibroblasts (CFs). LncR-30245 was mainly located in the cytoplasm. Overexpression of lncR-30245 promoted collagen production and CF proliferation. Knockdown of lncR-30245 significantly inhibited TGF-β1-induced collagen production and CF proliferation. LncR-30245 overexpression inhibited the antifibrotic role of peroxisome proliferator-activated receptor (PPAR)-γ and increased connective tissue growth factor (CTGF) expression, whereas lncR-30245 knockdown exerted the opposite effects. Rosiglitazone, a PPAR-γ agonist, significantly inhibited lncR-30245-induced CTGF upregulation and collagen production in CFs. In contrast, T0070907, a PPAR-γ antagonist, attenuated the inhibitory effects of lncR-30245 small interfering RNA (siRNA) on TGF-β1-induced CTGF expression and collagen production. LncR-30245 knockdown significantly enhanced ejection fraction and fractional shortening and attenuated cardiac fibrosis in MI mice.

CONCLUSION

Our study indicates that the lncR-30245/PPAR-γ/CTGF pathway mediates MI-induced cardiac fibrosis and might be a therapeutic target for various cardiac diseases associated with fibrosis.

Cardiac fibrosis: new insights into the pathogenesis

Cardiac fibrosis is defined as the imbalance of extracellular matrix (ECM) production and degradation, thus contributing to cardiac dysfunction in many cardiac pathophysiologic conditions. This review discusses specific markers and origin of cardiac fibroblasts (CFs), and the underlying mechanism involved in the development of cardiac fibrosis. Currently, there are no CFs-specific molecular markers. Most studies use co-labelling with panels of antibodies that can recognize CFs. Origin of fibroblasts is heterogeneous. After fibrotic stimuli, the levels of myocardial pro-fibrotic growth factors and cytokines are increased. These pro-fibrotic growth factors and cytokines bind to its receptors and then trigger the activation of signaling pathway and transcriptional factors via Smad-dependent or Smad independent-manners. These fibrosis-related transcriptional factors regulate gene expression that are involved in the fibrosis to amplify the fibrotic response. Understanding the mechanisms responsible for initiation, progression, and amplification of cardiac fibrosis are of great clinical significance to find drugs that can prevent the progression of cardiac fibrosis.

Treatment with a New Peroxisome Proliferator-Activated Receptor Gamma Agonist, Pyridinecarboxylic Acid Derivative, Increases Angiogenesis and Reduces Inflammatory Mediators in the Heart of Trypanosoma cruzi-Infected Mice

Trypanosoma cruzi infection induces an intense inflammatory response in diverse host tissues. The immune response and the microvascular abnormalities associated with infection are crucial aspects in the generation of heart damage in Chagas disease. Upon parasite uptake, macrophages, which are involved in the clearance of infection, increase inflammatory mediators, leading to parasite killing. The exacerbation of the inflammatory response may lead to tissue damage. Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-dependent nuclear transcription factor that exerts important anti-inflammatory effects and is involved in improving endothelial functions and proangiogenic capacities. In this study, we evaluated the intermolecular interaction between PPARγ and a new synthetic PPARγ ligand, HP₂₄, using virtual docking. Also, we showed that early treatment with HP₂₄, decreases the expression of NOS2, a pro-inflammatory mediator, and stimulates proangiogenic mediators (vascular endothelial growth factor A, CD31, and Arginase I) both in macrophages and in the heart of T. cruzi-infected mice. Moreover, HP₂₄ reduces the inflammatory response, cardiac fibrosis and the levels of inflammatory cytokines (TNF-α, interleukin 6) released by macrophages of T. cruzi-infected mice. We consider that PPARγ agonists might be useful as coadjuvants of the antiparasitic treatment of Chagas disease, to delay, reverse, or preclude the onset of heart damage.

Evaluation of circulating levels of CCN2/connective tissue growth factor in patients with ST-elevation myocardial infarction

CCN2/Connective tissue growth factor seems to be involved in development of cardiac hypertrophy and fibrosis, but a possible cardioprotective role in left ventricular (LV) remodelling following myocardial infarction has also been suggested. The main objectives of the study were therefore to investigate whether circulating CCN2 levels were associated with infarct size, LV function, adverse remodelling or clinical outcome in two cohorts of patients with ST-elevation myocardial infarction (STEMI). CCN2 was measured in 988 patients 18 hours after PCI and clinical events were recorded after 55 months in the BAMI cohort. In the POSTEMI trial, serial measurements of CCN2 were performed in 258 STEMI patients during index hospitalisation and cardiac magnetic resonance imaging was performed in the acute phase and after 4 months. Clinical events were also recorded. There were no significant associations between levels of CCN2 and infarct size, LV ejection fraction, changes in LV end-diastolic or end-systolic volume, myocardial salvage or microvascular obstruction. There were no significant associations between CCN2 levels and clinical events including mortality, in either of the study cohorts. In conclusion, circulating levels of CCN2 measured in the acute phase of STEMI were not associated with final infarct size, left ventricular function or new clinical events.

Dipeptidyl peptidase-4 (DPP-4) inhibition with linagliptin reduces western diet-induced myocardial TRAF3IP2 expression, inflammation and fibrosis in female mice

Background

Diastolic dysfunction (DD), a hallmark of obesity and primary defect in heart failure with preserved ejection fraction, is a predictor of future cardiovascular events. We previously reported that linagliptin, a dipeptidyl peptidase-4 inhibitor, improved DD in Zucker Obese rats, a genetic model of obesity and hypertension. Here we investigated the cardioprotective effects of linagliptin on development of DD in western diet (WD)-fed mice, a clinically relevant model of overnutrition and activation of the renin-angiotensin-aldosterone system.

Methods

Female C56Bl/6 J mice were fed an obesogenic WD high in fat and simple sugars, and supplemented or not with linagliptin for 16 weeks.

Results

WD induced oxidative stress, inflammation, upregulation of Angiotensin II type 1 receptor and mineralocorticoid receptor (MR) expression, interstitial fibrosis, ultrastructural abnormalities and DD. Linagliptin inhibited cardiac DPP-4 activity and prevented molecular impairments and associated functional and structural abnormalities. Further, WD upregulated the expression of TRAF3IP2, a cytoplasmic adapter molecule and a regulator of multiple inflammatory mediators. Linagliptin inhibited its expression, activation of its downstream signaling intermediates NF-κB, AP-1 and p38-MAPK, and induction of multiple inflammatory mediators and growth factors that are known to contribute to development and progression of hypertrophy, fibrosis and contractile dysfunction. Linagliptin also inhibited WD-induced collagens I and III expression. Supporting these in vivo observations, linagliptin inhibited aldosterone-mediated MR-dependent oxidative stress, upregulation of TRAF3IP2, proinflammatory cytokine, and growth factor expression, and collagen induction in cultured primary cardiac fibroblasts. More importantly, linagliptin inhibited aldosterone-induced fibroblast activation and migration.

Conclusions

Together, these in vivo and in vitro results suggest that inhibition of DPP-4 activity by linagliptin reverses WD-induced DD, possibly by targeting TRAF3IP2 expression and its downstream inflammatory signaling.

Connective tissue growth factor and bone morphogenetic protein 2 are induced following myocardial ischemia in mice and humans

We aimed to study the cardiac expression of bone morphogenetic protein 2, its receptor 1 b, and connective tissue growth factor, factors implicated in cardiac embryogenesis, following ischemia/hypoxia, heart failure, and in remodeling hearts from humans and mice. Biopsies from the left ventricle of patients with end-stage heart failure due to dilated cardiomyopathy or coronary artery disease were compared with donor hearts and biopsies from patients with normal heart function undergoing coronary artery bypass grafting. Mouse model of post-infarction remodeling was made by permanent ligation of the left coronary artery. Hearts were analyzed by real-time polymerase chain reaction and Western blotting after 24 hours and after 2 and 4 weeks. Patients with dilated cardiomyopathy and mice post-infarction had increased cardiac expression of connective tissue growth factor. Bone morphogenetic protein 2 was increased in human hearts failing due to coronary artery disease and in mice post-infarction. Gene expression of bone morphogenetic protein receptor 1 beta was reduced in hearts of patients with failure, but increased two weeks following permanent ligation of the left coronary artery in mice. In conclusion, connective tissue growth factor is upregulated in hearts of humans with dilated cardiomyopathy, bone morphogenetic protein 2 is upregulated in remodeling due to myocardial infarction while its receptor 1 b in human failing hearts is downregulated. A potential explanation might be an attempt to engage regenerative processes, which should be addressed by further, mechanistic studies.

Rac1 GTPase regulates 11β hydroxysteroid dehydrogenase type 2 and fibrotic remodeling

The aim of the study was to characterize the role of Rac1 GTPase for the mineralocorticoid receptor (MR)-mediated pro-fibrotic remodeling. Transgenic mice with cardiac overexpression of constitutively active Rac1 (RacET) develop an age-dependent phenotype with atrial dilatation, fibrosis, and atrial fibrillation. Expression of MR was similar in RacET and WT mice. The expression of 11β hydroxysteroid dehydrogenase type 2 (11β-HSD2) was age-dependently up-regulated in the atria and the left ventricles of RacET mice on mRNA and protein levels. Statin treatment inhibiting Rac1 geranylgeranylation reduced 11β-HSD2 up-regulation. Samples of human left atrial myocardium showed a positive correlation between Rac1 activity and 11β-HSD2 expression (r = 0.7169). Immunoprecipitation showed enhanced Rac1-bound 11β-HSD2 relative to Rac1 expression in RacET mice that was diminished with statin treatment. Both basal and phorbol 12-myristate 13-acetate (PMA)-induced NADPH oxidase activity were increased in RacET and correlated positively with 11β-HSD2 expression (r = 0.788 and r = 0.843, respectively). In cultured H9c2 cardiomyocytes, Rac1 activation with l-buthionine sulfoximine increased; Rac1 inhibition with NSC23766 decreased 11β-HSD2 mRNA and protein expression. Connective tissue growth factor (CTGF) up-regulation induced by aldosterone was prevented with NSC23766. Cardiomyocyte transfection with 11β-HSD2 siRNA abolished the aldosterone-induced CTGF up-regulation. Aldosterone-stimulated MR nuclear translocation was blocked by the 11β-HSD2 inhibitor carbenoxolone. In cardiac fibroblasts, nuclear MR translocation induced by aldosterone was inhibited with NSC23766 and spironolactone. NSC23766 prevented the aldosterone-induced proliferation and migration of cardiac fibroblasts and the up-regulation of CTGF and fibronectin. In conclusion, Rac1 GTPase regulates 11β-HSD2 expression, MR activation, and MR-mediated pro-fibrotic signaling.

The diagnostic value of plasma N-terminal connective tissue growth factor levels in children with heart failure

OBJECTIVE

The aim of this study was to assess the diagnostic value of plasma N-terminal connective tissue growth factor in children with heart failure. Methods and results Plasma N-terminal connective tissue growth factor was determined in 61 children, including 41 children with heart failure, 20 children without heart failure, and 30 healthy volunteers. The correlations between plasma N-terminal connective tissue growth factor levels and clinical parameters were investigated. Moreover, the diagnostic value of N-terminal connective tissue growth factor levels was evaluated. Compared with healthy volunteers and children without heart failure, plasma N-terminal connective tissue growth factor levels were significantly elevated in those with heart failure (p0.05), but it obviously improved the ability of diagnosing heart failure in children, as demonstrated by the integrated discrimination improvement (6.2%, p=0.013) and net re-classification improvement (13.2%, p=0.017) indices.

CONCLUSIONS

Plasma N-terminal connective tissue growth factor is a promising diagnostic biomarker for heart failure in children.

Cardiac biomarkers in pediatric heart disease: A state of art review

Every year there are more than 11000 hospitalizations related to heart failure in children resulting in significant morbidity and mortality. Over the last two decades, our understanding, diagnosis and management of pediatric heart failure is evolving but our ability to prognosticate outcomes in pediatric heart acute heart failure is extremely limited due to lack of data. In adult heart failure patients, the role of cardiac biomarkers has exponentially increased over the last two decades. Current guidelines for management of heart failure emphasize the role of cardiac biomarkers in diagnosis, management and prognostication of heart failure. It is also noteworthy that these biomarkers reflect important biological processes that also open up the possibility of therapeutic targets. There is however, a significant gap present in the pediatric population with regards to biomarkers in pediatric heart failure. Here, we seek to review available data regarding cardiac biomarkers in the pediatric population and also explore some of the emerging biomarkers from adult literature that may be pertinent to pediatric heart failure.

Molecular mechanisms of the antiglycative and cardioprotective activities of Psidium guajava leaves in the rat diabetic myocardium

CONTEXT

Antiglycative potential of Psidium guajava L. (Myrtaceae) leaves has been established. However, the molecular basis of its antiglycative potential remains unknown.

OBJECTIVE

The ethyl acetate fraction of P. guajava leaves (PGEt) was evaluated to determine the cardioprotective effect and its mechanism of action compared to quercetin.

MATERIALS AND METHODS

After the induction of diabetes by streptozotocin (55 mg/kg body weight), PGEt and quercetin (50 mg/kg body weight) was administered for 60 days. Rats were grouped as follows: Group C: Control, Group D: Diabetic, Group D + E: Diabetic rats treated with PGEt, Group D + Q: Diabetic rats treated with quercetin. The antiglycative potential was evaluated by assaying glycosylated haemoglobin, serum fructosamine and advanced glycation end product levels. The differential receptor for advanced glycation end products and nuclear factor kappa B (NFκB) protein levels was determined by western blot and the transcript level changes of connective tissue growth factor (CTGF), brain natriuretic peptide (BNP) and TGF-β1 in heart tissue were assessed by RT-PCR analysis.

RESULTS

Glycated haemoglobin and serum fructosamine levels were found to be enhanced in diabetic rats when compared with control. Administration of PGEt significantly reduced the glycated haemoglobin and fructosamine levels to a larger extent than quercetin treated diabetic rats. PGEt reduced the translocation of NFκB from cytosol to nucleus when compared with diabetic rats. Expression of TGF-β1, CTGF and BNP was downregulated in PGEt treated groups compared with diabetic controls.

DISCUSSION AND CONCLUSION

Administration of PGEt ameliorated diabetes associated changes in the myocardium to a greater extent than quercetin.

Cardiac Hepcidin Expression Associates with Injury Independent of Iron

BACKGROUND

Hepcidin regulates systemic iron homeostasis by downregulating the iron exporter ferroportin. Circulating hepcidin is mainly derived from the liver but hepcidin is also produced in the heart. We studied the differential and local regulation of hepcidin gene expression in response to myocardial infarction (MI) and/or chronic kidney disease (CKD). We hypothesized that cardiac hepcidin gene expression is induced by and regulated to severity of cardiac injury, either through direct (MI) or remote (CKD) stimuli, as well as through increased local iron content.

METHODS

Nine weeks after subtotal nephrectomy (SNX) or sham surgery (CON), rats were subjected to coronary ligation (CL) or sham surgery to realize 4 groups: CON, SNX, CL and SNX + CL. In week 16, the gene expression of hepcidin, iron and damage markers in cardiac and liver tissues was assessed by quantitative polymerase chain reaction and ferritin protein expression was studied by immunohistochemistry.

RESULTS

Cardiac hepcidin messenger RNA (mRNA) expression was increased 2-fold in CL (p = 0.03) and 3-fold in SNX (p = 0.01). Cardiac ferritin staining was not different among groups. Cardiac hepcidin mRNA expression correlated with mRNA expression levels of brain natriuretic peptide (β = 0.734, p < 0.001) and connective tissue growth factor (β = 0.431, p = 0.02). In contrast, liver hepcidin expression was unaffected by SNX and CL alone, while it had decreased 50% in SNX + CL (p < 0.05). Hepatic ferritin immunostaining was not different among groups.

CONCLUSIONS

Our data indicate differences in hepcidin regulation in liver and heart and suggest a role for injury rather than iron as the driving force for cardiac hepcidin expression in renocardiac failure.

Cardiac-restricted Overexpression of TRAF3 Interacting Protein 2 (TRAF3IP2) Results in Spontaneous Development of Myocardial Hypertrophy, Fibrosis, and Dysfunction

TRAF3IP2 (TRAF3 interacting protein 2; previously known as CIKS or Act1) is a key intermediate in the normal inflammatory response and the pathogenesis of various autoimmune and inflammatory diseases. Induction of TRAF3IP2 activates IκB kinase (IKK)/NF-κB, JNK/AP-1, and c/EBPβ and stimulates the expression of various inflammatory mediators with negative myocardial inotropic effects. To investigate the role of TRAF3IP2 in heart disease, we generated a transgenic mouse model with cardiomyocyte-specific TRAF3IP2 overexpression (TRAF3IP2-Tg). Echocardiography, magnetic resonance imaging, and pressure-volume conductance catheterization revealed impaired cardiac function in 2-month-old male transgenic (Tg) mice as evidenced by decreased ejection fraction, stroke volume, cardiac output, and peak ejection rate. Moreover, the male Tg mice spontaneously developed myocardial hypertrophy (increased heart/body weight ratio, cardiomyocyte cross-sectional area, GATA4 induction, and fetal gene re-expression). Furthermore, TRAF3IP2 overexpression resulted in the activation of IKK/NF-κB, JNK/AP-1, c/EBPβ, and p38 MAPK and induction of proinflammatory cytokines, chemokines, and extracellular matrix proteins in the heart. Although myocardial hypertrophy decreased with age, cardiac fibrosis (increased number of myofibroblasts and enhanced expression and deposition of fibrillar collagens) increased progressively. Despite these adverse changes, TRAF3IP2 overexpression did not result in cell death at any time period. Interestingly, despite increased mRNA expression, TRAF3IP2 protein levels and activation of its downstream signaling intermediates remained unchanged in the hearts of female Tg mice. The female Tg mice also failed to develop myocardial hypertrophy. In summary, these results demonstrate that overexpression of TRAF3IP2 in male mice is sufficient to induce myocardial hypertrophy, cardiac fibrosis, and contractile dysfunction.

Peroxisome Proliferator-Activated Receptor-γ Is Critical to Cardiac Fibrosis

Peroxisome proliferator-activated receptor-γ (PPARγ) is a ligand-activated transcription factor belonging to the nuclear receptor superfamily, which plays a central role in regulating lipid and glucose metabolism. However, accumulating evidence demonstrates that PPARγ agonists have potential to reduce inflammation, influence the balance of immune cells, suppress oxidative stress, and improve endothelial function, which are all involved in the cellular and molecular mechanisms of cardiac fibrosis. Thus, in this review we discuss the role of PPARγ in various cardiovascular conditions associated with cardiac fibrosis, including diabetes mellitus, hypertension, myocardial infarction, heart failure, ischemia/reperfusion injury, atrial fibrillation, and several other cardiovascular disease (CVD) conditions, and summarize the developmental status of PPARγ agonists for the clinical management of CVD.

Elevated Plasma Connective Tissue Growth Factor Levels in Children with Pulmonary Arterial Hypertension Associated with Congenital Heart Disease

We aimed to investigate plasma connective tissue growth factor (CTGF) levels in pulmonary arterial hypertension (PAH) associated with congenital heart disease (CHD) (PAH-CHD) in children and the relationships of CTGF with hemodynamic parameters. Plasma CTGF levels were calculated in 30 children with CHD, 30 children with PAH-CHD and 25 health volunteers, using the subtraction method. Cardiac catheterization was performed to measure clinical hemodynamic parameters. Plasma CTGF levels were significantly higher in PAH-CHD than in those with CHD and health volunteers (p < 0.01). In cyanotic PAH-CHD, plasma CTGF levels were significantly elevated compared with acyanotic PAH-CHD in the same group (p < 0.05). Plasma CTGF levels showed positive correlation with B-type natriuretic peptide (BNP) in PAH-CHD (r = 0.475, p < 0.01), while oxygen saturation was inversely related to plasma CTGF levels (r = -0.436, p < 0.05). There was no correlation between CTGF and hemodynamic parameters. Even though the addition of CTGF to BNP did not significantly increase area under curve for diagnosis of PAH-CHD compared with BNP alone (p > 0.05), it revealed a moderately better specificity, positive predictive value and positive likelihood ratio than BNP alone. Plasma CTGF levels could be a promising diagnostic biomarker for PAH-CHD in children.

Pioglitazone Protected against Cardiac Hypertrophy via Inhibiting AKT/GSK3β and MAPK Signaling Pathways

Peroxisome proliferator activated receptor γ (PPARγ) has been closely involved in the process of cardiovascular diseases. This study was to investigate whether pioglitazone (PIO), a PPARγ agonist, could protect against pressure overload-induced cardiac hypertrophy. Mice were orally given PIO (2.5 mg/kg) from 1 week after aortic banding and continuing for 7 weeks. The morphological examination and biochemical analysis were used to evaluate the effects of PIO. Neonatal rat ventricular cardiomyocytes were also used to verify the protection of PIO against hypertrophy in vitro. The results in our study demonstrated that PIO remarkably inhibited hypertrophic response induced by aortic banding in vivo. Besides, PIO also suppressed cardiac fibrosis in vivo. PIO treatment also inhibited the activation of protein kinase B (AKT)/glycogen synthase kinase-3β (GSK3β) and mitogen-activated protein kinase (MAPK) in the heart. In addition, PIO alleviated angiotensin II-induced hypertrophic response in vitro. In conclusion, PIO could inhibit cardiac hypertrophy via attenuation of AKT/GSK3β and MAPK pathways.

Adiponectin Upregulates MiR-133a in Cardiac Hypertrophy through AMPK Activation and Reduced ERK1/2 Phosphorylation

Adiponectin and miR-133a are key regulators in cardiac hypertrophy. However, whether APN has a potential effect on miR-133a remains unclear. In this study, we aimed to investigate whether APN could regulate miR-133a expression in Angiotensin II (Ang II) induced cardiac hypertrophy in vivo and in vitro. Lentiviral-mediated adiponectin treatment attenuated cardiac hypertrophy induced by Ang II infusion in male wistar rats as determined by reduced cell surface area and mRNA levels of atrial natriuretic peptide (ANF) and brain natriuretic peptide (BNP), also the reduced left ventricular end-diastolic posterior wall thickness (LVPWd) and end-diastolic interventricular septal thickness (IVSd). Meanwhile, APN elevated miR-133a level which was downregulated by Ang II. To further investigate the underlying molecular mechanisms, we treated neonatal rat ventricular myocytes (NRVMs) with recombinant rat APN before Ang II stimulation. Pretreating cells with recombinant APN promoted AMP-activated protein kinase (AMPK) phosphorylation and inhibited ERK activation. By using the inhibitor of AMPK or a lentiviral vector expressing AMPK short hairpin RNA (shRNA) cancelled the positive effect of APN on miR-133a. The ERK inhibitor PD98059 reversed the downregulation of miR-133a induced by Ang II. These results indicated that the AMPK activation and ERK inhibition were responsible for the positive effect of APN on miR-133a. Furthermore, adiponectin receptor 1 (AdipoR1) mRNA expression was inhibited by Ang II stimulation. The positive effects of APN on AMPK activation and miR-133a, and the inhibitory effect on ERK phosphorylation were inhibited in NRVMs transfected with lentiviral AdipoR1shRNA. In addition, APN depressed the elevated expression of connective tissue growth factor (CTGF), a direct target of miR-133a, through the AMPK pathway. Taken together, our data indicated that APN reversed miR-133a levels through AMPK activation, reduced ERK1/2 phosphorylation in cardiomyocytes stimulated with Ang II, revealing a previously undemonstrated and important link between APN and miR-133a.

Disruption of collagen homeostasis can reverse established age-related myocardial fibrosis

Heart failure, the leading cause of hospitalization of elderly patients, is correlated with myocardial fibrosis (ie, deposition of excess extracellular matrix proteins such as collagen). A key regulator of collagen homeostasis is lysyl oxidase (LOX), an enzyme responsible for cross-linking collagen fibers. Our objective was to ameliorate age-related myocardial fibrosis by disrupting collagen cross-linking through inhibition of LOX. The nonreversible LOX inhibitor β-aminopropionitrile (BAPN) was administered by osmotic minipump to 38-week-old C57BL/6J male mice for 2 weeks. Sirius Red staining of myocardial cross sections revealed a reduction in fibrosis, compared with age-matched controls (5.84 ± 0.30% versus 10.17 ± 1.34%) (P < 0.05), to a level similar to that of young mice at 8 weeks (4.9 ± 1.2%). BAPN significantly reduced COL1A1 mRNA, compared with age-matched mice (3.5 ± 0.3-fold versus 15.2 ± 4.9-fold) (P < 0.05), suggesting that LOX is involved in regulation of collagen synthesis. In accord, fibrotic factor mRNA expression was reduced after BAPN. There was also a novel increase in Ly6C expression by resident macrophages. By interrupting collagen cross-linking by LOX, the BAPN treatment reduced myocardial fibrosis. A novel observation is that BAPN treatment modulated the transforming growth factor-β pathway, collagen synthesis, and the resident macrophage population. This is especially valuable in terms of potential therapeutic targeting of collagen regulation and thereby age-related myocardial fibrosis.

Connective tissue growth factor regulates cardiac function and tissue remodeling in a mouse model of dilated cardiomyopathy

Cardiac structural changes associated with dilated cardiomyopathy (DCM) include cardiomyocyte hypertrophy and myocardial fibrosis. Connective tissue growth factor (CTGF) has been associated with tissue remodeling and is highly expressed in failing hearts. Our aim was to test if inhibition of CTGF would alter the course of cardiac remodeling and preserve cardiac function in the protein kinase Cε (PKCε) mouse model of DCM. Transgenic mice expressing constitutively active PKCε in cardiomyocytes develop cardiac dysfunction that was evident by 3 months of age, and that progressed to cardiac fibrosis, heart failure, and increased mortality. Beginning at 3 months of age, PKCε mice were treated with a neutralizing monoclonal antibody to CTGF (FG-3149) for an additional 3 months. CTGF inhibition significantly improved left ventricular (LV) systolic and diastolic functions in PKCε mice, and slowed the progression of LV dilatation. Using gene arrays and quantitative PCR, the expression of many genes associated with tissue remodeling was elevated in PKCε mice, but significantly decreased by CTGF inhibition. However total collagen deposition was not attenuated. The observation of significantly improved LV function by CTGF inhibition in PKCε mice suggests that CTGF inhibition may benefit patients with DCM. Additional studies to explore this potential are warranted.

Regulation of Connective Tissue Growth Factor and Cardiac Fibrosis by an SRF/MicroRNA-133a Axis

Myocardial fibrosis contributes to the remodeling of heart and the loss of cardiac function leading to heart failure. SRF is a transcription factor implicated in the regulation of a large variety of genes involved in cardiac structure and function. To investigate the impact of an SRF overexpression in heart, we developed a new cardiac-specific and tamoxifen-inducible SRF overexpression mouse model by the Cre/loxP strategy. Here, we report that a high level overexpression of SRF leads to severe modifications of cardiac cytoarchitecture affecting the balance between cardiomyocytes and cardiac fibroblasts and also a profound alteration of cardiac gene expression program. The drastic development of fibrosis was characterized by intense sirius red staining and associated with an increased expression of genes encoding extracellular matrix proteins such as fibronectin, procollagen type 1α1 and type 3α1 and especially connective tissue growth factor (CTGF). Furthermore miR-133a, one of the most predominant cardiac miRNAs, is strongly downregulated when SRF is overexpressed. By comparison a low level overexpression of SRF has minor impact on these different processes. Investigation with miR-133a, antimiR-133a and AdSRF-VP16 experiments in H9c2 cardiac cells demonstrated that: 1)–miR-133a acts as a repressor of SRF and CTGF expression; 2)–a simultaneous overexpression of SRF by AdSRF-VP16 and inhibition of miR-133a by a specific antimiR increase CTGF expression; 3)–miR-133a overexpression can block the upregulation of CTGF induced by AdSRF-VP16. Taken together, these findings reveal a key role of the SRF/CTGF/miR-133a axis in the regulation of cardiac fibrosis.

CTGF knockout does not affect cardiac hypertrophy and fibrosis formation upon chronic pressure overload

BACKGROUND

One of the main contributors to maladaptive cardiac remodeling is fibrosis. Connective tissue growth factor (CTGF), a matricellular protein that is secreted into the cardiac extracellular matrix by both cardiomyocytes and fibroblasts, is often associated with development of fibrosis. However, recent studies have questioned the role of CTGF as a pro-fibrotic factor. Therefore, we aimed to investigate the effect of CTGF on cardiac fibrosis, and on functional, structural, and electrophysiological parameters in a mouse model of CTGF knockout (KO) and chronic pressure overload.

METHODS AND RESULTS

A new mouse model of global conditional CTGF KO induced by tamoxifen-driven deletion of CTGF, was subjected to 16weeks of chronic pressure overload via transverse aortic constriction (TAC, control was sham surgery). CTGF KO TAC mice presented with hypertrophic hearts, and echocardiography revealed a decrease in contractility on a similar level as control TAC mice. Ex vivo epicardial mapping showed a low incidence of pacing-induced ventricular arrhythmias (2/12 in control TAC vs. 0/10 in CTGF KO TAC, n.s.) and a tendency towards recovery of the longitudinal conduction velocity of CTGF KO TAC hearts. Picrosirius Red staining on these hearts unveiled increased fibrosis at a similar level as control TAC hearts. Furthermore, genes related to fibrogenesis were also similarly upregulated in both TAC groups. Histological analysis revealed an increase in fibronectin and vimentin protein expression, a significant reduction in connexin43 (Cx43) protein expression, and no difference in NaV1.5 expression of CTGF KO ventricles as compared with sham treated animals.

CONCLUSION

Conditional CTGF inhibition failed to prevent TAC-induced cardiac fibrosis and hypertrophy. Additionally, no large differences were found in other parameters between CTGF KO and control TAC mice. With no profound effect of CTGF on fibrosis formation, other factors or pathways are likely responsible for fibrosis development.

Oleanolic acid alleviated pressure overload-induced cardiac remodeling

Previous study has demonstrated that oleanolic acid (OA) possessing the anti-inflammatory and anti-oxidant properties blunted high-glucose-induced diabetic cardiomyopathy and ameliorated experimental autoimmune myocarditis in mice. However, little is known about its effects on pressure overload-induced cardiac remodeling. Herein, we investigated the effect of OA on cardiac remodeling and underlying mechanism. Mice, subjected to aortic banding (AB), were randomly assigned into control group and experimental group. OA premixed in diets was administered to mice after 3 days of AB. Echocardiography and catheter-based measurements of hemodynamic parameters were performed after 8 weeks' treatment of OA. Histologic examination and molecular analyses were used to assess cardiac hypertrophy and tissue fibrosis. In addition, the inhibitory effects of OA on H9c2 cardiomyocytes and cardiac primary fibroblast responded to the stimulation of AngII were also investigated. OA ameliorated the systolic and diastolic dysfunction induced by pressure overload evidenced by echocardiography and catheter-based measurements. OA also decreased the mRNA expression of cardiac hypertrophy and fibrosis markers evidenced by RT-PCR. It has been shown in our study that pressure overload activated the phosphorylations of Akt, mTOR, p70s6k, S6, GSK3β, and FoxO3a, and treatment of OA attenuated the phosphorylation of these proteins. In addition, hypertrophy of cardiomyocytes and fibrosis markers induced by AngII was inhibited by OA in vitro. Our findings uncover that OA suppressed AB-induced cardiac hypertrophy, partly by inhibiting the activity of Akt/mTOR pathway, and suggest that treatment of OA may have a benefit on retarding the progress of cardiac remodeling under long terms of pressure overload.

Harnessing endogenous stem/progenitor cells for tendon regeneration

Current stem cell-based strategies for tissue regeneration involve ex vivo manipulation of these cells to confer features of the desired progenitor population. Recently, the concept that endogenous stem/progenitor cells could be used for regenerating tissues has emerged as a promising approach that potentially overcomes the obstacles related to cell transplantation. Here we applied this strategy for the regeneration of injured tendons in a rat model. First, we identified a rare fraction of tendon cells that was positive for the known tendon stem cell marker CD146 and exhibited clonogenic capacity, as well as multilineage differentiation ability. These tendon-resident CD146+ stem/progenitor cells were selectively enriched by connective tissue growth factor delivery (CTGF delivery) in the early phase of tendon healing, followed by tenogenic differentiation in the later phase. The time-controlled proliferation and differentiation of CD146+ stem/progenitor cells by CTGF delivery successfully led to tendon regeneration with densely aligned collagen fibers, normal level of cellularity, and functional restoration. Using siRNA knockdown to evaluate factors involved in tendon generation, we demonstrated that the FAK/ERK1/2 signaling pathway regulates CTGF-induced proliferation and differentiation of CD146+ stem/progenitor cells. Together, our findings support the use of endogenous stem/progenitor cells as a strategy for tendon regeneration without cell transplantation and suggest this approach warrants exploration in other tissues.

Anti-Fibrotic Effects of Class I HDAC Inhibitor, Mocetinostat Is Associated with IL-6/Stat3 Signaling in Ischemic Heart Failure

BACKGROUND

Recent studies have linked histone deacetylases (HDAC) to remodeling of the heart and cardiac fibrosis in heart failure. However, the molecular mechanisms linking chromatin remodeling events with observed anti-fibrotic effects are unknown. Here, we investigated the molecular players involved in anti-fibrotic effects of HDAC inhibition in congestive heart failure (CHF) myocardium and cardiac fibroblasts in vivo.

METHODS AND RESULTS

MI was created by coronary artery occlusion. Class I HDACs were inhibited in three-week post MI rats by intraperitoneal injection of Mocetinostat (20 mg/kg/day) for duration of three weeks. Cardiac function and heart tissue were analyzed at six week post-MI. CD90+ cardiac fibroblasts were isolated from ventricles through enzymatic digestion of heart. In vivo treatment of CHF animals with Mocetinostat reduced CHF-dependent up-regulation of HDAC1 and HDAC2 in CHF myocardium, improved cardiac function and decreased scar size and total collagen amount. Moreover, expression of pro-fibrotic markers, collagen-1, fibronectin and Connective Tissue Growth Factor (CTGF) were reduced in the left ventricle (LV) of Mocetinostat-treated CHF hearts. Cardiac fibroblasts isolated from Mocetinostat-treated CHF ventricles showed a decrease in expression of collagen I and III, fibronectin and Timp1. In addition, Mocetinostat attenuated CHF-induced elevation of IL-6 levels in CHF myocardium and cardiac fibroblasts. In parallel, levels of pSTAT3 were reduced via Mocetinostat in CHF myocardium.

CONCLUSIONS

Anti-fibrotic effects of Mocetinostat in CHF are associated with the IL-6/STAT3 signaling pathway. In addition, our study demonstrates in vivo regulation of cardiac fibroblasts via HDAC inhibition.

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.

Connective tissue growth factor inhibition attenuates left ventricular remodeling and dysfunction in pressure overload-induced heart failure

Connective tissue growth factor (CTGF) is involved in the pathogenesis of various fibrotic disorders. However, its role in the heart is not clear. To investigate the role of CTGF in regulating the development of cardiac fibrosis and heart failure, we subjected mice to thoracic aortic constriction (TAC) or angiotensin II infusion, and antagonized the function of CTGF with CTGF monoclonal antibody (mAb). After 8 weeks of TAC, mice treated with CTGF mAb had significantly better preserved left ventricular (LV) systolic function and reduced LV dilatation compared with mice treated with control immunoglobulin G. CTGF mAb-treated mice exhibited significantly smaller cardiomyocyte cross-sectional area and reduced expression of hypertrophic marker genes. CTGF mAb treatment reduced the TAC-induced production of collagen 1 but did not significantly attenuate TAC-induced accumulation of interstitial fibrosis. Analysis of genes regulating extracellular matrix proteolysis showed decreased expression of plasminogen activator inhibitor-1 and matrix metalloproteinase-2 in mice treated with CTGF mAb. In contrast to TAC, antagonizing the function of CTGF had no effect on LV dysfunction or LV hypertrophy in mice subjected to 4-week angiotensin II infusion. Further analysis showed that angiotensin II-induced expression of hypertrophic marker genes or collagens was not affected by treatment with CTGF mAb. In conclusion, CTGF mAb protects from adverse LV remodeling and LV dysfunction in hearts subjected to pressure overload by TAC. Antagonizing the function of CTGF may offer protection from cardiac end-organ damage in patients with hypertension.

Transcriptional changes in bone marrow stromal cells of patients with heart failure

It is proposed that patients with heart failure may have not only myocardial dysfunction, but also a reduced regenerative capacity of stem cells. However, very little is known about bone marrow stromal cell (BMSC) characteristics in heart failure and its comorbidities (obesity and/or diabetes). We hypothesized that metabolic alterations associated with the latter will be reflected in altered expression of key genes related to angiogenesis, inflammation, and tissue remodeling in patient-derived BMSCs. We found that BMSCs of heart failure patients with lower body mass index have enhanced expression of genes involved in extracellular matrix remodeling. In particular, body mass index<30 was associated with upregulated expression of genes encoding collagen type I, proteases and protease activators (MMP2, MMP14, uPA), and regulatory molecules (CTGF, ITGβ5, SMAD7, SNAIL1). In contrast, these transcript levels did not differ significantly between BMSCs from obese heart failure patients and healthy subjects. Comorbidities (including obesity and diabetes) are known to play role in heart failure progression rate and outcome of the disease. We thus suggest that key molecular targets identified in this study should become the target of the subsequent focused studies. In the future, these targets may find some use in the clinical setting.

Abnormal muscle mechanosignaling triggers cardiomyopathy in mice with Marfan syndrome

Patients with Marfan syndrome (MFS), a multisystem disorder caused by mutations in the gene encoding the extracellular matrix (ECM) protein fibrillin 1, are unusually vulnerable to stress-induced cardiac dysfunction. The prevailing view is that MFS-associated cardiac dysfunction is the result of aortic and/or valvular disease. Here, we determined that dilated cardiomyopathy (DCM) in fibrillin 1-deficient mice is a primary manifestation resulting from ECM-induced abnormal mechanosignaling by cardiomyocytes. MFS mice displayed spontaneous emergence of an enlarged and dysfunctional heart, altered physical properties of myocardial tissue, and biochemical evidence of chronic mechanical stress, including increased angiotensin II type I receptor (AT1R) signaling and abated focal adhesion kinase (FAK) activity. Partial fibrillin 1 gene inactivation in cardiomyocytes was sufficient to precipitate DCM in otherwise phenotypically normal mice. Consistent with abnormal mechanosignaling, normal cardiac size and function were restored in MFS mice treated with an AT1R antagonist and in MFS mice lacking AT1R or β-arrestin 2, but not in MFS mice treated with an angiotensin-converting enzyme inhibitor or lacking angiotensinogen. Conversely, DCM associated with abnormal AT1R and FAK signaling was the sole abnormality in mice that were haploinsufficient for both fibrillin 1 and β1 integrin. Collectively, these findings implicate fibrillin 1 in the physiological adaptation of cardiac muscle to elevated workload.