Transforming growth factor-beta(1) expression in dilated cardiomyopathy

Downregulation of lncRNA Miat contributes to the protective effect of electroacupuncture against myocardial fibrosis

Background

Myocardial fibrosis changes the structure of myocardium, leads to cardiac dysfunction and induces arrhythmia and cardiac ischemia, threatening patients’ lives. Electroacupuncture at PC6 (Neiguan) was previously found to inhibit myocardial fibrosis. Long non-coding RNAs (lncRNAs) play a variety of regulatory functions in myocardial fibrosis, but whether electroacupuncture can inhibit myocardial fibrosis by regulating lncRNA has rarely been reported.

Methods

In this study, we constructed myocardial fibrosis rat models using isoproterenol (ISO) and treated rats with electroacupuncture at PC6 point and non-point as control. Hematoxylin–eosin, Masson and Sirius Red staining were performed to assess the pathological changes and collagen deposition. The expression of fibrosis-related markers in rat myocardial tissue were detected by RT-qPCR and Western blot. Miat, an important long non-coding RNA, was selected to study the regulation of myocardial fibrosis by electroacupuncture at the transcriptional and post-transcriptional levels. In post-transcriptional level, we explored the myocardial fibrosis regulation effect of Miat on the sponge effect of miR-133a-3p. At the transcriptional level, we studied the formation of heterodimer PPARG–RXRA complex and promotion of the TGF-β1 transcription.

Results

Miat was overexpressed by ISO injection in rats. We found that Miat can play a dual regulatory role in myocardial fibrosis. Miat can sponge miR-133a-3p in an Ago2-dependent manner, reduce the binding of miR-133a-3p target to the 3ʹUTR region of CTGF mRNA and improve the protein expression level of CTGF. In addition, it can also directly bind with PPARG protein, inhibit the formation of heterodimer PPARG–RXRA complex and then promote the transcription of TGF-β1. Electroacupuncture at PC6 point, but not at non-points, can reduce the expression of Miat, thus inhibiting the expression of CTGF and TGF-β1 and inhibiting myocardial fibrosis.

Conclusion

We revealed that electroacupuncture at PC6 point can inhibit the process of myocardial fibrosis by reducing the expression of lncRNA Miat, which is a potential therapeutic method for myocardial fibrosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-022-00615-6.

Biphasic changes in TGF-β1 signaling drive NSAID-induced multi-organ damage

The clinical utility of non-steroidal anti-inflammatory drugs (NSAIDs), used extensively worldwide, is limited by adverse cardiac events resulting from chronic drug exposure. Here, we provide evidence identifying transforming growth factor β (TGF-β1), released from multiple tissues, as a critical driver of NSAID-induced multi-organ damage. Biphasic changes in TGF-β1 levels in liver and heart were accompanied by ROS generation, cell death, fibrotic remodeling, compromised cardiac contractility and elevated liver enzymes. Pharmacological inhibition of TGF-βRI signaling markedly improved heart and liver function and increased overall survival of animals exposed to multiple NSAIDs, effects likely mediated by reductions in NOX-dependent ROS generation. Notably, the beneficial impact of TGF-βRI blockade was confined to a critical window wherein consecutive, but not concurrent, inhibitor administration improved cardiac and hepatic endpoints. Remarkably, in addition to ameliorating indomethacin-mediated myofilament disruptions, cardiac TGF-βRI knockdown lead to drastic reductions in TGF-β1 production accompanied by lessening in intestinal lesioning underscoring the importance of endocrine TGF-β1 signaling in NSAID-driven tissue injury. Indeed, gastric ulceration was associated with a higher incidence of cardiac complications in a human cohort underscoring the critical importance of circulation-facilitated peripheral organ system interconnectedness in efforts seeking to mitigate the toxic side effects of chronic NSAID use.

Pleural Fluid Cytokine Levels at Baseline and Over Time are Associated With Time to IPC Removal: An Exploratory Study

BACKGROUND

The behavior of pleural fluid cytokine (PFCs) levels and their association with pleurodesis after indwelling pleural catheter (IPC) placement is unknown.

OBJECTIVE

A prospective exploratory study was conducted to obtain preliminary data on PFC levels after IPC placement.

METHODS

The PFC panel consisted of 4 cytokines [interleukin -8 (IL-8), vascular endothelial growth factor, total (but not activated) transforming growth factor betas, and basic fibroblast growth factor], measured across 5 time points (T0: insertion; T1: 24 to 48 h; T2: 72 to 96 h; T3: 1 wk; and T4: 2 wk). Profile plots were used to identify patterns of change of PFC levels. Correlation matrices for each PFC over time were computed, and area under the curve (AUC) categories were used to compare the cumulative incidence of IPC removal. Auto pleurodesis was defined as elective catheter removal because of decreased drainage within 90 days of insertion.

RESULTS

A total of 22 patients provided complete data. Except for IL-8, the majority of PFCs demonstrated strong positive correlations across measurement time points. Patients with high AUCs for IL-8, basic fibroblast growth factor, and vascular endothelial growth factor had a higher cumulative incidence of IPC removal by 90 days than did patients with low AUCs.

CONCLUSION

This is the first study to evaluate longitudinal changes of pleural cytokine levels with respect to the likelihood of IPC removal and provide early evidence that the cytokine profile may be associated with the outcome of pleurodesis induced by IPCs. However, this is an exploratory study and further studies are needed to assess if these findings can be validated in further studies.

Ca2+ Signaling in Cardiac Fibroblasts and Fibrosis-Associated Heart Diseases

Cardiac fibrosis is the excessive deposition of extracellular matrix proteins by cardiac fibroblasts and myofibroblasts, and is a hallmark feature of most heart diseases, including arrhythmia, hypertrophy, and heart failure. This maladaptive process occurs in response to a variety of stimuli, including myocardial injury, inflammation, and mechanical overload. There are multiple signaling pathways and various cell types that influence the fibrogenesis cascade. Fibroblasts and myofibroblasts are central effectors. Although it is clear that Ca2+ signaling plays a vital role in this pathological process, what contributes to Ca2+ signaling in fibroblasts and myofibroblasts is still not wholly understood, chiefly because of the large and diverse number of receptors, transporters, and ion channels that influence intracellular Ca2+ signaling. Intracellular Ca2+ signals are generated by Ca2+ release from intracellular Ca2+ stores and by Ca2+ entry through a multitude of Ca2+-permeable ion channels in the plasma membrane. Over the past decade, the transient receptor potential (TRP) channels have emerged as one of the most important families of ion channels mediating Ca2+ signaling in cardiac fibroblasts. TRP channels are a superfamily of non-voltage-gated, Ca2+-permeable non-selective cation channels. Their ability to respond to various stimulating cues makes TRP channels effective sensors of the many different pathophysiological events that stimulate cardiac fibrogenesis. This review focuses on the mechanisms of Ca2+ signaling in fibroblast differentiation and fibrosis-associated heart diseases and will highlight recent advances in the understanding of the roles that TRP and other Ca2+-permeable channels play in cardiac fibrosis.

Late gadolinium enhancement on cardiac magnetic resonance combined with 123I- metaiodobenzylguanidine scintigraphy strongly predicts long-term clinical outcome in patients with dilated cardiomyopathy

Late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) is limited in its ability to detect diffuse interstitial fibrosis, which is commonly found in idiopathic dilated cardiomyopathy (DCM). On the other hand, Washout rate (WR) by cardiac ¹²³I- metaiodobenzylguanidine (¹²³I-MIBG) scintigraphy which evaluates cardiac sympathetic nervous function, is a useful tool for predicting the prognosis in DCM. We investigated the predictive value of the combination of two different types of examinations, LGE on CMR and WR by ¹²³I-MIBG scintigraphy for outcomes in DCM compared with LGE alone. One-hundred forty-eight DCM patients underwent CMR and ¹²³I-MIBG scintigraphy. Patients were divided into 4 groups according to the presence or absence of LGE and WR cut-off value of 45% for predicting prognosis based on receiver operating characteristic curve analysis. Cardiac deaths, re-hospitalization for heart failure, implantation of a left ventricular assist device, and life-threatening ventricular arrhythmias were defined as clinical events. Forty-two DCM patients reached the clinical events during the median follow-up for 9.1 years (interquartile range, 8.0–9.2 years).Multivariable Cox regression analysis identified WR≥45%+LGE positive group as an independent predictor of cardiac events (HR 3.18, 95%CI 1.36–7.45, p = 0.008). Notably, there was no significance in the cardiac event-free survival rate between the WR<45%+LGE positive and WR≥45%+LGE negative groups (p = 0.89). The combination of WR by ¹²³I-MIBG scintigraphy and LGE on CMR, which evaluate different type of cardiac deterioration, serves as a stronger predictor of long-term outcomes in DCM patients than LGE alone.

Advanced Evolution of Pathogenesis Concepts in Cardiomyopathies

Cardiomyopathy is a group of heterogeneous cardiac diseases that impair systolic and diastolic function, and can induce chronic heart failure and sudden cardiac death. Cardiomyopathy is prevalent in the general population, with high morbidity and mortality rates, and contributes to nearly 20% of sudden cardiac deaths in younger individuals. Genetic mutations associated with cardiomyopathy play a key role in disease formation, especially the mutation of sarcomere encoding genes and ATP kinase genes, such as titin, lamin A/C, myosin heavy chain 7, and troponin T1. Pathogenesis of cardiomyopathy occurs by multiple complex steps involving several pathways, including the Ras-Raf-mitogen-activated protein kinase-extracellular signal-activated kinase pathway, G-protein signaling, mechanotransduction pathway, and protein kinase B/phosphoinositide 3-kinase signaling. Excess biomechanical stress induces apoptosis signaling in cardiomyocytes, leading to cell loss, which can induce myocardial fibrosis and remodeling. The clinical features and pathophysiology of cardiomyopathy are discussed. Although several basic and clinical studies have investigated the mechanism of cardiomyopathy, the detailed pathophysiology remains unclear. This review summarizes current concepts and focuses on the molecular mechanisms of cardiomyopathy, especially in the signaling from mutation to clinical phenotype, with the aim of informing the development of therapeutic interventions.

Downregulation of AC061961.2, LING01-AS1, and RP11-13E1.5 is associated with dilated cardiomyopathy progression

This study aimed to explore long noncoding RNAs (lncRNAs) implicated in dilated cardiomyopathy (DCM). Ten samples of failing hearts collected from the left ventricles of patients with DCM undergoing heart transplants, and ten control samples obtained from normal heart donors were included in this study. After sequencing, differentially expressed genes (DEGs) and lncRNAs between DCM and controls were screened, followed with functional enrichment analysis and weighted gene coexpression network analysis (WGCNA). Five key lncNRAs were validated through real-time polymerase chain reaction (PCR). Total 1,398 DEGs were identified, including 267 lncRNAs. WGCNA identified seven modules that were significantly correlated with DCM. The top 50 genes in the three modules (black, dark-green, and green-yellow) were significantly correlated with DCM disease state. Four core enrichment lncRNAs, such as AC061961.2, LING01-AS1, and RP11-557H15.4, in the green-yellow module were associated with neurotransmitter secretion. Five core enrichment lncRNAs, such as KB-1299A7.2 and RP11-13E1.5, in the black module were associated with the functions of blood circulation and heart contraction. AC061961.2, LING01-AS1, and RP11-13E1.5 were confirmed to be downregulated in DCM tissues by real-time PCR. The current study suggests that downregulation of AC061961.2, LING01-AS1, and RP11-13E1.5 may be associated with DCM progression, which may serve as key diagnostic biomarkers and therapeutic targets for DCM.

New methodologies to accurately assess circulating active transforming growth factor-β1 levels: implications for evaluating heart failure and the impact of left ventricular assist devices

Transforming growth factor-β1 (TGF-β1) has been used as a biomarker in disorders associated with pathologic fibrosis. However, plasma TGF-β1 assessment is confounded by the significant variation in reported normal values, likely reflecting variable release of the large pool of platelet TGF-β1 after blood drawing. Moreover, current assays measure only total TGF-β1, which is dominated by the latent form of TGF-β1 rather than the biologically active form. To address these challenges, we developed methodologies to prevent ex vivo release of TGF-β1 and to quantify active TGF-β1. We then used these techniques to measure TGF-β1 in healthy controls and patients with heart failure (HF) before and after insertion of left ventricular assist devices (LVAD). Total plasma TGF-β1 was 1.0 ± 0.60 ng/mL in controls and 3.76 ± 1.55 ng/mL in subjects with HF (P < 0.001), rising to 5.2 ± 2.3 ng/mL following LVAD placement (P = 0.006). These results were paralleled by the active TGF-β1 values; controls had 3-16 pg/mL active TGF-β1, whereas levels were 2.7-fold higher in patients with HF before, and 4.2-fold higher after, LVAD implantation. Total TGF-β1 correlated with levels of the platelet-derived protein thrombospondin-1 (r = 0.87; P < 0.001), suggesting that plasma TGF-β1 may serve as a surrogate indicator of in vivo platelet activation. von Willebrand factor high molecular weight multimers correlated inversely with TGF-β1 levels (r = -0.63; P = 0.023), suggesting a role for shear forces in loss of these multimers and platelet activation. In conclusion, accurate assessment of circulating TGF-β1 may provide a valuable biomarker for in vivo platelet activation and thrombotic disorders.

Retinoic acid and sodium butyrate suppress the cardiac expression of hypertrophic markers and proinflammatory mediators in Npr1 gene-disrupted haplotype mice

The objective of the present study was to examine the genetically determined differences in the natriuretic peptide receptor-A (NPRA) gene (Npr1) copies affecting the expression of cardiac hypertrophic markers, proinflammatory mediators, and matrix metalloproteinases (MMPs) in a gene-dose-dependent manner. We determined whether stimulation of Npr1 by all-trans retinoic acid (RA) and histone deacetylase (HDAC) inhibitor sodium butyric acid (SB) suppress the expression of cardiac disease markers. In the present study, we utilized Npr1 gene-disrupted heterozygous (Npr1(+/-), 1-copy), wild-type (Npr1(+/+), 2-copy), gene-duplicated (Npr1(++/+), 3-copy) mice, which were treated intraperitoneally with RA, SB, and a combination of RA/SB, a hybrid drug (HB) for 2 wk. Untreated 1-copy mice showed significantly increased heart weight-body weight (HW/BW) ratio, blood pressure, hypertrophic markers, including beta-myosin heavy chain (β-MHC) and proto-oncogenes (c-fos and c-jun), proinflammatory mediator nuclear factor kappa B (NF-κB), and MMPs (MMP-2, MMP-9) compared with 2-copy and 3-copy mice. The heterozygous (haplotype) 1-copy mice treated with RA, SB, or HB, exhibited significant reduction in the expression of β-MHC, c-fos, c-jun, NF-κB, MMP-2, and MMP-9. In drug-treated animals, the activity and expression levels of HDAC were significantly reduced and histone acetyltransferase activity and expression levels were increased. The drug treatments significantly increased the fractional shortening and reduced the systolic and diastolic parameters of the Npr1(+/-) mice hearts. Together, the present results demonstrate that a decreased Npr1 copy number enhanced the expression of hypertrophic markers, proinflammatory mediators, and MMPs, whereas an increased Npr1 repressed the cardiac disease markers in a gene-dose-dependent manner.

Genotype-Specific Interaction of Latent TGFβ Binding Protein 4 with TGFβ

Latent TGFβ binding proteins are extracellular matrix proteins that bind latent TGFβ to form the large latent complex. Nonsynonymous polymorphisms in LTBP4, a member of the latent TGFβ binding protein gene family, have been linked to several human diseases, underscoring the importance of TGFβ regulation for a range of phenotypes. Because of strong linkage disequilibrium across the LTBP4 gene, humans have two main LTBP4 alleles that differ at four amino acid positions, referred to as IAAM and VTTT for the encoded residues. VTTT is considered the “risk” allele and associates with increased intracellular TGFβ signaling and more deleterious phenotypes in muscular dystrophy and other diseases. We now evaluated LTBP4 nsSNPs in dilated cardiomyopathy, a distinct disorder associated with TGFβ signaling. We stratified based on self-identified ethnicity and found that the LTBP4 VTTT allele is associated with increased risk of dilated cardiomyopathy in European Americans extending the diseases that associate with LTBP4 genotype. However, the association of LTBP4 SNPs with dilated cardiomyopathy was not observed in African Americans. To elucidate the mechanism by which LTBP4 genotype exerts this differential effect, TGFβ’s association with LTBP4 protein was examined. LTBP4 protein with the IAAM residues bound more latent TGFβ compared to the LTBP4 VTTT protein. Together these data provide support that LTBP4 genotype exerts its effect through differential avidity for TGFβ accounting for the differences in TGFβ signaling attributed to these two alleles.

Cardiac Fibrosis Alleviated by Exercise Training Is AMPK-Dependent

Regular exercise can protect the heart against external stimuli, but the mechanism is not well understood. We determined the role of adenosine monophosphate-activated protein kinase (AMPK) in regulating swimming exercise-mediated cardiac protection against β-adrenergic receptor overstimulation with isoproterenol (ISO) in mice. Ten-week-old AMPKα2^+/+ and AMPKα2-knockout (AMPKα2^-/-) littermates were subjected to 4 weeks of swimming training (50 min daily, 6 days a week) or housed under sedentary conditions. The mice received daily subcutaneous injection of ISO (5 mg/kg/d), a nonselective β-adrenergic receptor agonist, during the last 2 weeks of swimming training. Swimming training alleviated ISO-induced cardiac fibrosis in AMPKα2^+/+ mice but not AMPKα2^-/- mice. Swimming training activated cardiac AMPK in AMPKα2^+/+ mice. Furthermore, swimming training attenuated ISO-induced production of reactive oxygen species (ROS) and expression of NADPH oxidase and promoted the expression of antioxidant enzymes in AMPKα2^+/+ mice but not AMPKα2^-/- mice. In conclusion, swimming training attenuates ISO-induced cardiac fibrosis by inhibiting the NADPH oxidase–ROS pathway mediated by AMPK activation. Our findings provide a new mechanism for the cardioprotective effects of exercise.

The role of TGFβ1 and LRG1 in cardiac remodelling and heart failure

Heart failure is a life-threatening condition that carries a considerable emotional and socio-economic burden. As a result of the global increase in the ageing population, sedentary life-style, increased prevalence of risk factors, and improved survival from cardiovascular events, the incidence of heart failure will continue to rise. Despite the advances in current cardiovascular therapies, many patients are not suitable for or may not benefit from conventional treatments. Thus, more effective therapies are required. Transforming growth factor (TGF) β family of cytokines is involved in heart development and dys-regulated TGFβ signalling is commonly associated with fibrosis, aberrant angiogenesis and accelerated progression into heart failure. Therefore, a potential therapeutic pathway is to modulate TGFβ signalling; however, broad blockage of TGFβ signalling may cause unwanted side effects due to its pivotal role in tissue homeostasis. We found that leucine-rich α-2 glycoprotein 1 (LRG1) promotes blood vessel formation via regulating the context-dependent endothelial TGFβ signalling. This review will focus on the interaction between LRG1 and TGFβ signalling, their involvement in the pathogenesis of heart failure, and the potential for LRG1 to function as a novel therapeutic target.

Regulatory mechanism of gallic acid against advanced glycation end products induced cardiac remodeling in experimental rats

Advanced glycation end products (AGEs) play a major role in the development of cardiovascular disorders in diabetic patients. Recent studies evidenced the beneficial role of phytochemicals in reducing the risk of cardiovascular diseases. Hence the present study was framed to investigate the protective role of Gallic acid (GA) on AGEs induced cardiac fibrosis. Rats were infused with in vitro prepared AGEs (50mg/kg BW-intravenous injection) for 30 days. Further, GA (25mg/kgBW) was administered to rats along with AGEs. On infusion of AGEs, induction of fibrotic markers, collagen deposition, oxidative marker NADPH oxidase (NOX-p47 phox subunit), AGE receptor (RAGE) and cytokines expression was evaluated in the heart tissues using RT-PCR, Western blot and immunostaining methods. AGEs infusion significantly (P<0.01) increased the HW/BW ratio and fibrosis (4-fold) with increased expression of matrix genes MMP-2 and -9 (P<0.01, respectively) in the heart tissues. Whereas, administration of GA along with AGEs infusion prevented the fibrosis induced by AGEs. Further, GA treatment effectively prevented the AGEs mediated up-regulation of pro-fibrotic genes and ECM proteins such as TNF-α, TGF-β, MMP-2 and -9 expression. In addition, the increased expression of NOX (P<0.01), RAGE (P<0.01), NF-κB (P<0.01) and ERK 1/2 on AGEs infusion were normalized by GA treatment. Thus the present study shows the protective effect of GA on the fibrotic response and cardiac remodeling process induced by advanced glycation end products from external sources.

Phenanthrene exposure produces cardiac defects during embryo development of zebrafish (Danio rerio) through activation of MMP-9

Phenanthrene (Phe) is one of the most abundant polycyclic aromatic hydrocarbons in the aquatic environment as a result of human activities. It is widely accepted that Phe has cardiotoxic effects. Even so, knowledge concerning the mechanism(s) of cardiac development toxicity is still limited. In this study, we exposed zebrafish embryos to environmentally relevant concentrations of Phe and then investigated its cardiotoxic effects and the mechanism(s) involved. Some cardiac morphogenetic defects, which was characterized by an abnormally looped and enlarged heart, dilated and thinner ventricular wall, and increased interstitial fibrosis, were observed in the Phe treated groups. The mRNA and protein expression levels of matrix metalloproteinase-9 (MMP-9), as well as the MMP-9 activity, were induced. Moreover, during co-treatment of the zebrafish embryos with MMP-9 inhibitor, the cardiac defects caused by Phe were attenuated. In addition, Phe exposure led to an up-regulation of transforming growth factor β (TGF-β), which plays a crucial role in mediating cardiac fibrosis. Taken together, our data indicated that the exposure to Phe of zebrafish embryos disrupted normal cardiac development, and that the cardiac defects induced by Phe were mediated by the MMP-9, while TGF-β was also involved in these cardiac defects.

Quantification of active and total transforming growth factor-β levels in serum and solid organ tissues by bioassay

BACKGROUND

Transforming growth factor-β (TGF-β) is a multi-factorial peptide growth factor that has a vital role in the regulation of cell growth, differentiation, inflammation, and tissue repair. Quantification of biologically active TGF-β levels in tissues is crucial to illustrate mechanisms involved in various physiological and pathological processes, but direct measurement of bioactive TGF-β level in the tissue has been hampered by lack of reliable methods. Here, we introduced mink lung epithelial cell bioassay to quantify both active and total TGF-β levels in serum and protein lysates from solid organs in the mouse model.

FINDINGS

Mink lung epithelial cells were stably transfected with plasminogen activator inhibitor-1 promoter/luciferase construct, in which bioactive TGF-β level was represented by luciferase activity. Serum total TGF-β levels were comparable between the bioassay and enzyme-linked immunosorbent assay (ELISA), but active TGF-β levels measured by ELISA were significantly lower than those obtained by the bioassay. Active and total TGF-β levels in the solid organs including heart, liver, and kidney were also measured. Total TGF-β levels were relatively comparable among these organs, but active TGF-β levels were slightly higher in hearts and kidneys than in livers. Positive luciferase activities in the bioassay were almost completely inhibited by adding pan-TGF-β neutralizing antibodies, suggesting its high specificity to bioactive TGF-β. We also measured myocardial TGF-β levels after myocardial infarction and sham control by the bioassay, and compared the values with those obtained by ELISA. The bioassay demonstrated that both active and total tissue TGF-β levels were significantly higher in post-myocardial infarction than in sham myocardium. ELISA was markedly less sensitive in detecting both active and total TGF-β levels than our bioassay and failed to show any statistically significant difference in TGF-β levels between myocardial infarction and sham myocardium.

CONCLUSIONS

Our data suggested that the bioassay was significantly more sensitive than ELISA in detecting active TGF-β in serum and both active and total TGF-β in solid organ tissues. The bioassay will be useful in investigating TGF-β profile in various solid organs in physiological and pathological conditions.

Systemic inflammation and cell activation reflects morbidity in chronic heart failure

Chronic heart failure (CHF) leads to complex effects distant from the heart. As these changes may be reflected in the balance of systemic inflammatory and fibrotic immunomodulators we measured these potential biomarkers in ambulatory CHF patients. Using the New York Heart Association (NYHA; levels II-IV) functional classification, 30 CHF patients were compared with 21 age and gender matched controls. Peripheral blood levels of regulatory cytokines (TNF-α, TGF-β, KGF, IL-8, IL-10 and IL-12) and markers of cellular activation (CD11b, CD16, CD18, CD34, HLADR, CXCR1 and CCR5) were analysed by ELISA and flow cytometry, respectively. NYHA classification, which reflected increasing pulmonary microvascular pressure (E:E') but not ejection fraction, was positively associated with TGF-β and IL-10 (p≤0.03). Similarly, monocytes, as well as cell surface expression of the neutrophil adhesion molecule CD11b, and the macrophage complement receptor complex (CD11b/CD18), were increased in CHF patients (p≤0.03), while the chemokine receptor CXCR1 was decreased on cells of CHF patients. Twenty month follow-up of CHF subjects identified monocyte number as a powerful prognostic factor for cardio-pulmonary adverse events (p=0.001); however, no concurrent relationship with cellular activation marker expression was found. In subjects with CHF, monocytes, TGF-β, IL-10, CD11b/CD18 and CXCR1 expression in peripheral blood may act as novel biomarkers of immune activation and remodelling. Given the importance of dyspnea and the relationship of pulmonary microvascular pressure to the NYHA classification, we suggest these findings may reflect a contribution by the lung.

Molecular mechanisms underlying cardiac antihypertrophic and antifibrotic effects of natriuretic peptides

Natriuretic peptides (NPs) exert well-characterized protective effects on the cardiovascular system, such as vasorelaxation, natri- and diuresis, increase of endothelial permeability, and inhibition of renin-angiotensin-aldosterone system. It has been reported that they also possess antihypertrophic and antifibrotic properties and contribute actively to cardiac remodeling. As a consequence, they are involved in several aspects of cardiovascular diseases. Antihypertrophic and antifibrotic actions of NPs appear to be mediated by specific signaling pathways within a more complex cellular network. Elucidation of the molecular mechanisms underlying the effects of NPs on cardiac remodeling represents an important research objective in order to gain more insights on the complex network leading to cardiac hypertrophy, ventricular dysfunction, and transition to heart failure, and in the attempt to develop novel therapeutic agents. The aim of the present article is to review well-characterized molecular mechanisms underlying the antihypertrophic and antifibrotic effects of NPs in the heart that appear to be mainly mediated by guanylyl cyclase type A receptor. In particular, we discuss the calcineurin/NFAT, the sodium exchanger NHE-1, and the TGFβ1/Smad signaling pathways. The role of guanylyl cyclase type B receptor, along with the emerging functional significance of natriuretic peptide receptor type C as mediators of CNP antihypertrophic and antifibrotic actions in the heart are also considered.

Association between transforming growth factor beta1 polymorphisms and atrial fibrillation in essential hypertensive subjects

Background

The association of TGF β1 polymorphisms and atrial fibrillation (AF) in essential hypertensive (EH) subjects remains unknown. Methods EH subjects with AF (EH+AF+) and sinus rhythm (EH+AF-) were enrolled. The polymorphisms of +869 T → C at codon 10 and + 915 G → C at codon 25, were genotyped. The clinical characteristics including serum TGF β1 levels were detected.

Results

The GG genotypes of TGF β1 +915 G → C at codon 25 were more prevalent in subjects from EH+AF+ group than those from EH+AF- group (P = 0.009). The subjects with GG genotype from EH+AF+ group had the highest mean serum TGF β1 level, which was significantly higher than that of GG genotype subjects from EH+AF- group (3.18 ± 0.24 ng/dl vs.2.29 ± 0.14 ng/dl, P < 0.05). Multiple analyses revealed that the TGF β1 GG genotype of +915 G → C at codon 25 presented a 3.09 times higher risk in developing AF in the multivariate model after adjusting for age and gender.

Conclusion

The polymorphisms of TGF β1 +915 G → C at codon 25 were associated with occurrence of AF and serum TGF β1 level in EH subjects.

ANKRD1, the gene encoding cardiac ankyrin repeat protein, is a novel dilated cardiomyopathy gene

OBJECTIVES

We evaluated ankyrin repeat domain 1 (ANKRD1), the gene encoding cardiac ankyrin repeat protein (CARP), as a novel candidate gene for dilated cardiomyopathy (DCM) through mutation analysis of a cohort of familial or idiopathic DCM patients, based on the hypothesis that inherited dysfunction of mechanical stretch-based signaling is present in a subset of DCM patients.

BACKGROUND

CARP, a transcription coinhibitor, is a member of the titin-N2A mechanosensory complex and translocates to the nucleus in response to stretch. It is up-regulated in cardiac failure and hypertrophy and represses expression of sarcomeric proteins. Its overexpression results in contractile dysfunction.

METHODS

In all, 208 DCM patients were screened for mutations/variants in the coding region of ANKRD1 using polymerase chain reaction, denaturing high-performance liquid chromatography, and direct deoxyribonucleic acid sequencing. In vitro functional analyses of the mutation were performed using yeast 2-hybrid assays and investigating the effect on stretch-mediated gene expression in myoblastoid cell lines using quantitative real-time reverse transcription-polymerase chain reaction.

RESULTS

Three missense heterozygous ANKRD1 mutations (P105S, V107L, and M184I) were identified in 4 DCM patients. The M184I mutation results in loss of CARP binding with Talin 1 and FHL2, and the P105S mutation in loss of Talin 1 binding. Intracellular localization of mutant CARP proteins is not altered. The mutations result in differential stretch-induced gene expression compared with wild-type CARP.

CONCLUSIONS

ANKRD1 is a novel DCM gene, with mutations present in 1.9% of DCM patients. The ANKRD1 mutations may cause DCM as a result of disruption of the normal cardiac stretch-based signaling.

Serum transforming growth factor-beta1 as a risk stratifier of sudden cardiac death

Sudden cardiac death prematurely claims the lives of some 7 million each year worldwide. It occurs primarily in patients with an underlying structural cardiac abnormality, and regardless of the type of the underlying pathology (heart failure, dilated and hypertrophic cardiomyopathies, myocardial infarction and aging), death is almost always caused by ventricular tachycardia (VT) which rapidly degenerates to ventricular fibrillation (VF). Implantable cardioverter defibrillator is an effective but expensive therapy for preventing SCD, and finding a reasonably specific, sensitive and cost-effective risk stratification tool for patients at high risk of sudden cardiac death will have great clinical utility in preventing premature sudden cardiac death. Increased myocardial fibrosis has been shown to develop in a wide range of cardiac diseases all manifesting increased risk of VT and VF. Clinical and experimental studies attribute a major role for fibrosis in the initiation of VT, VF and sudden cardiac death. Transforming growth factor-beta1 (TGF-beta1) has been shown to promote myocardial tissue fibrosis and perhaps more importantly in cardiac conditions associated with increased myocardial fibrosis are shown to be positively correlated with increased serum levels of TGF-beta1. In the present hypothesis we suggest that monitoring the serum levels of TGF-beta1 may be a cost-effective risk stratifier to identify patients at high risk of sudden cardiac death caused by VT and VF.

Plasma connective tissue growth factor is a novel potential biomarker of cardiac dysfunction in patients with chronic heart failure

BACKGROUND

Connective tissue growth factor (CTGF) has been recently reported as a mediator of myocardial fibrosis; however, the significance of plasma CTGF concentration has not been evaluated in patients with heart failure. The aim of this study was to investigate the clinical utility of plasma CTGF concentration for the diagnosis of heart failure.

METHODS AND RESULTS

We evaluated fifty-two patients with chronic heart failure. The plasma concentration of CTGF and other markers of fibrosis were assessed and compared with clinical and echocardiographic data. Plasma CTGF was significantly elevated in symptomatic patients in proportion to their NYHA classes and was significantly correlated with plasma brain natriuretic peptide (BNP) concentration (r=0.395, P<0.01). Plasma CTGF was also correlated with plasma transforming growth factor beta (TGF-beta) (r=0.512, P<0.01), matrix metalloproteinase (MMP)-2 (r=0.391, P<0.05) and tissue inhibitor of MMP (TIMP)-2 (r=0.354, P<0.05) concentrations. Interestingly, plasma CTGF was correlated with E/E' value evaluated by tissue Doppler echocardiography (r=0.593, P=0.012), but not with systolic function and left ventricular mass.

CONCLUSION

Our study suggests that plasma CTGF concentration is a novel diagnostic marker for cardiac dysfunction and may provide additional specific information about myocardial fibrosis in chronic heart failure patients.

Role of TGF-beta1 haplotypes in the occurrence of myocardial infarction in young Italian patients

Background

Transforming growth factor beta 1 (TGF-β1) gene play an important role in the acute myocardial infarction (AMI), however no investigation has been conducted so far in young AMI patients.

In this study, we evaluated the influence of TGF-β1 polymorphisms/haplotypes on the onset and progression of AMI in young Italian population.

Methods

201 cases and 201 controls were genotyped for three TGF-β1 polymorphisms (G-800A, C-509T and Leu10Pro). The main follow-up end-points (mean follow-up, 107 ± 49 months) were death, myocardial infarction or revascularization procedures.

Results

Significant risk factors were smoking (p < 10^-4), family history for coronary artery disease (p < 10^-4), hypercholesterolemia (p = 0.001) and hypertension (p = 0.002). The C-509T and Leu10Pro polymorphisms showed significant differences (p = 0.026 and p = 0.004) between cases and controls.

The most common haplotypes revealed a possible protective effect (GCT, OR 0.75, 95% CI 0.57–0.99, p = 0.042) and an increased risk of AMI (GTC, OR 1.51, 95% CI 1.13–2.02, p = 0.005), respectively.

No statistical differences were observed in genotype distribution in the follow-up study between the two groups: 61 patients with subsequent events (13 deaths) and 108 without events.

Conclusion

Even though our results need to be further confirmed in larger studies, this is the first study reporting on a possible role of TGFβ1 common haplotypes in the onset of AMI in young patients.

Examining potential therapies targeting myocardial fibrosis through the inhibition of transforming growth factor-beta 1

After injury, the heart undergoes a remodeling process consisting primarily of myocyte hypertrophy, apoptosis and interstitial fibrosis. Although initially beneficial, excess fibrosis gradually results in alteration of left ventricular properties and cardiac dysfunction. Transforming growth factor-beta 1 (TGF-beta(1)) is thought to be a primary mediator of fibrosis within the heart after injury. Currently, angiotensin II blockade is used to inhibit the actions of TGF-beta(1). However, recent studies indicate that angiotensin II blockade alone may not be sufficient to prevent TGF-beta(1)-induced fibrosis. Thus far, both in vivo and in vitro models have shown that direct TGF-beta(1) inhibition, NAPDH oxidase inhibitors, growth factors and hormonal treatment regimens targeting TGF-beta(1) may significantly reduce cardiac fibrosis after injury. This study attempts to underline these alternatives to angiotensin II blockade in combating TGF-beta(1)-induced cardiac dysfunction.

Fibrosis in heart disease: understanding the role of transforming growth factor-beta in cardiomyopathy, valvular disease and arrhythmia

The importance of fibrosis in organ pathology and dysfunction appears to be increasingly relevant to a variety of distinct diseases. In particular, a number of different cardiac pathologies seem to be caused by a common fibrotic process. Within the heart, this fibrosis is thought to be partially mediated by transforming growth factor-beta1 (TGF-beta1), a potent stimulator of collagen-producing cardiac fibroblasts. Previously, TGF-beta1 had been implicated solely as a modulator of the myocardial remodelling seen after infarction. However, recent studies indicate that dilated, ischaemic and hypertrophic cardiomyopathies are all associated with raised levels of TGF-beta1. In fact, the pathogenic effects of TGF-beta1 have now been suggested to play a major role in valvular disease and arrhythmia, particularly atrial fibrillation. Thus far, medical therapy targeting TGF-beta1 has shown promise in a multitude of heart diseases. These therapies provide great hope, not only for treatment of symptoms but also for prevention of cardiac pathology as well. As is stated in the introduction, most reviews have focused on the effects of cytokines in remodelling after myocardial infarction. This article attempts to underline the significance of TGF-beta1 not only in the post-ischaemic setting, but also in dilated and hypertrophic cardiomyopathies, valvular diseases and arrhythmias (focusing on atrial fibrillation). It also aims to show that TGF-beta1 is an appropriate target for therapy in a variety of cardiovascular diseases.

Pulmonary vein diameter reduction after radiofrequency catheter ablation for paroxysmal atrial fibrillation evaluated by contrast-enhanced three-dimensional magnetic resonance imaging

BACKGROUND

Radiofrequency catheter ablation (RFCA) is a promising intervention to treat atrial fibrillation. However, pulmonary vein (PV) stenosis after RFCA has been reported. The aim of this study was to investigate the incidence and time course of pulmonary vein stenosis after RFCA within a period of 3 months. Contrast-enhanced magnetic resonance angiography (MRA) was used to visualize pulmonary veins and was compared with radiographic angiography.

METHODS AND RESULTS

Forty-six consecutive patients with symptomatic paroxysmal atrial fibrillation had RFCA in the orifice of 138 pulmonary veins. Comparison of diameters measured in 44 untreated vessels either by radiographic angiography or with MRA established the reliability of MRA (r=0.934). MRA measurements revealed an incidence of relevant diameter reductions of > or =25% or stenosis of > or =50% after RFCA of 25 of 138 (18.1%) treated vessels 1 day and/or 3 months after ablation. A progression of diameter reduction after RFCA was observed in 8.3% (maximum 75%), whereas a regression was observed in 6.3% of treated PVs. Ablation at a radial angle of >180 degrees of a pulmonary vein orifice increased the risk of diameter reduction significantly compared with ablation at a radial angle < or =180 degrees (P=0.002).

CONCLUSIONS

The occurrence and progression of PV stenosis is a potential significant complication of RFCA in the orifice of pulmonary veins. These findings may have an impact on the technical performance of this intervention. In addition, long-term studies will be necessary to evaluate lumen reduction over time. MRA is a noninvasive, reproducible imaging modality for this purpose.