Essential role of Smad3 in infarct healing and in the pathogenesis of cardiac remodeling

ALK1 Deficiency Impairs the Wound-Healing Process and Increases Mortality in Murine Model of Myocardial Infarction

The functional role of TGFβ type I receptor, activin-like kinase (ALK)-1 in post-myocardial infarction (MI) cardiac remodeling is unknown. We hypothesize that reduced ALK1 activity reduces survival and promotes cardiac fibrosis after MI. MI was induced in wild-type (WT), and ALK+/- mice by left coronary ligation. After 14 days ALK1+/- mice had reduced survival with a higher rate of cardiac rupture compared to WT mice. ALK1+/- left ventricles (LVs) had increased volumes at the end of systole and at the end of diastole. After MI ALK1+/- LVs had increased profibrotic SMAD3 signaling, type 1 collagen, and fibrosis as well as increased levels of TGFβ1 co-receptor, endoglin, VEGF, and ALK1 ligands BMP9 and BMP10. ALK1+/- LVs had decreased levels of stromal-derived factor 1α. These data identify the critical role of ALK1 in post-MI survival and cardiac remodeling and implicate ALK1 as a potential therapeutic target to improve survival after MI.

Macrophages in cardiovascular diseases: molecular mechanisms and therapeutic targets

The immune response holds a pivotal role in cardiovascular disease development. As multifunctional cells of the innate immune system, macrophages play an essential role in initial inflammatory response that occurs following cardiovascular injury, thereby inducing subsequent damage while also facilitating recovery. Meanwhile, the diverse phenotypes and phenotypic alterations of macrophages strongly associate with distinct types and severity of cardiovascular diseases, including coronary heart disease, valvular disease, myocarditis, cardiomyopathy, heart failure, atherosclerosis and aneurysm, which underscores the importance of investigating macrophage regulatory mechanisms within the context of specific diseases. Besides, recent strides in single-cell sequencing technologies have revealed macrophage heterogeneity, cell-cell interactions, and downstream mechanisms of therapeutic targets at a higher resolution, which brings new perspectives into macrophage-mediated mechanisms and potential therapeutic targets in cardiovascular diseases. Remarkably, myocardial fibrosis, a prevalent characteristic in most cardiac diseases, remains a formidable clinical challenge, necessitating a profound investigation into the impact of macrophages on myocardial fibrosis within the context of cardiac diseases. In this review, we systematically summarize the diverse phenotypic and functional plasticity of macrophages in regulatory mechanisms of cardiovascular diseases and unprecedented insights introduced by single-cell sequencing technologies, with a focus on different causes and characteristics of diseases, especially the relationship between inflammation and fibrosis in cardiac diseases (myocardial infarction, pressure overload, myocarditis, dilated cardiomyopathy, diabetic cardiomyopathy and cardiac aging) and the relationship between inflammation and vascular injury in vascular diseases (atherosclerosis and aneurysm). Finally, we also highlight the preclinical/clinical macrophage targeting strategies and translational implications.

Receptor-activated transcription factors and beyond: multiple modes of Smad2/3-dependent transmission of TGF-β signaling

Transforming growth factor β (TGF-β) is a pleiotropic cytokine that is widely distributed throughout the body. Its receptor proteins, TGF-β type I and type II receptors, are also ubiquitously expressed. Therefore, the regulation of various signaling outputs in a context-dependent manner is a critical issue in this field. Smad proteins were originally identified as signal-activated transcription factors similar to signal transducer and activator of transcription proteins. Smads are activated by serine phosphorylation mediated by intrinsic receptor dual specificity kinases of the TGF-β family, indicating that Smads are receptor-restricted effector molecules downstream of ligands of the TGF-β family. Smad proteins have other functions in addition to transcriptional regulation, including post-transcriptional regulation of micro-RNA processing, pre-mRNA splicing, and m6A methylation. Recent technical advances have identified a novel landscape of Smad-dependent signal transduction, including regulation of mitochondrial function without involving regulation of gene expression. Therefore, Smad proteins are receptor-activated transcription factors and also act as intracellular signaling modulators with multiple modes of function. In this review, we discuss the role of Smad proteins as receptor-activated transcription factors and beyond. We also describe the functional differences between Smad2 and Smad3, two receptor-activated Smad proteins downstream of TGF-β, activin, myostatin, growth and differentiation factor (GDF) 11, and Nodal.

GSK3β: A ray of hope for the treatment of diabetic kidney disease

Diabetic kidney disease (DKD), a major microvascular complication of diabetes, is characterized by its complex pathogenesis, high risk of chronic renal failure, and lack of effective diagnosis and treatment methods. GSK3β (glycogen synthase kinase 3β), a highly conserved threonine/serine kinase, was found to activate glycogen synthase. As a key molecule of the glucose metabolism pathway, GSK3β participates in a variety of cellular activities and plays a pivotal role in multiple diseases. However, these effects are not only mediated by affecting glucose metabolism. This review elaborates on the role of GSK3β in DKD and its damage mechanism in different intrinsic renal cells. GSK3β is also a biomarker indicating the progression of DKD. Finally, the protective effects of GSK3β inhibitors on DKD are also discussed.

TGF-β as a therapeutic target in the infarcted and failing heart: cellular mechanisms, challenges, and opportunities

INTRODUCTION

Myocardial fibrosis accompanies most cardiac conditions and can be reparative or maladaptive. Transforming Growth Factor (TGF)-β is a potent fibrogenic mediator, involved in repair, remodeling, and fibrosis of the injured heart.

AREAS COVERED

This review manuscript discusses the role of TGF-β in heart failure focusing on cellular mechanisms and therapeutic implications. TGF-β is activated in infarcted, remodeling and failing hearts. In addition to its fibrogenic actions, TGF-β has a broad range of effects on cardiomyocytes, immune, and vascular cells that may have both protective and detrimental consequences. TGF-β-mediated effects on macrophages promote anti-inflammatory transition, whereas actions on fibroblasts mediate reparative scar formation and effects on pericytes are involved in maturation of infarct neovessels. On the other hand, TGF-β actions on cardiomyocytes promote adverse remodeling, and prolonged activation of TGF-β signaling in fibroblasts stimulates progression of fibrosis and heart failure.

EXPERT OPINION

Understanding of the cell-specific actions of TGF-β is necessary to design therapeutic strategies in patients with myocardial disease. Moreover, to implement therapeutic interventions in the heterogeneous population of heart failure patients, mechanism-driven classification of both HFrEF and HFpEF patients is needed. Heart failure patients with prolonged or overactive fibrogenic TGF-β responses may benefit from cautious TGF-β inhibition.

Therapeutic effect of Echinococcus granulosus cyst fluid on bacterial sepsis in mice

BACKGROUND

The primary pathophysiological process of sepsis is to stimulate a massive release of inflammatory mediators to trigger systemic inflammatory response syndrome (SIRS), the major cause of multi-organ dysfunction and death. Like other helminths, Echinococcus granulosus induces host immunomodulation. We sought to determine whether E. granulosus cyst fluid (EgCF) displays a therapeutic effect on sepsis-induced inflammation and tissue damage in a mouse model.

METHODS

The anti-inflammatory effects of EgCF were determined by in vitro culture with bone marrow-derived macrophages (BMDMs) and in vivo treatment of BALB/C mice with cecal ligation and puncture (CLP)-induced sepsis. The macrophage phenotypes were determined by flow cytometry, and the levels of cytokines in cell supernatants or in sera of mice were measured (ELISA). The therapeutic effect of EgCF on sepsis was evaluated by observing the survival rates of mice for 72 h after CLP, and the pathological injury to the liver, kidney, and lung was measured under a microscope. The expression of TLR-2/MyD88 in tissues was measured by western blot to determine whether TLR-2/MyD88 is involved in the sepsis-induced inflammatory signaling pathway.

RESULTS

In vitro culture with BMDMs showed that EgCF promoted macrophage polarization to M2 type and inhibited lipopolysaccharide (LPS)-induced M1 macrophages. EgCF treatment provided significant therapeutic effects on CLP-induced sepsis in mice, with increased survival rates and alleviation of tissue injury. The EgCF conferred therapeutic efficacy was associated with upregulated anti-inflammatory cytokines (IL-10 and TGF-β) and reduced pro-inflammatory cytokines (TNF-α and INF-γ). Treatment with EgCF induced Arg-1-expressed M2, and inhibited iNOS-expressed M1 macrophages. The expression of TLR-2 and MyD88 in EgCF-treated mice was reduced.

CONCLUSIONS

The results demonstrated that EgCF confers a therapeutic effect on sepsis by inhibiting the production of pro-inflammatory cytokines and inducing regulatory cytokines. The anti-inflammatory effect of EgCF is carried out possibly through inducing macrophage polarization from pro-inflammatory M1 to regulatory M2 phenotype to reduce excessive inflammation of sepsis and subsequent multi-organ damage. The role of EgCF in regulating macrophage polarization may be achieved by inhibiting the TLR2/MyD88 signaling pathway.

Leucine Supplementation Improves Diastolic Function in HFpEF by HDAC4 Inhibition

Heart failure with preserved ejection fraction (HFpEF) is a complex syndrome associated with a high morbidity and mortality rate. Leucine supplementation has been demonstrated to attenuate cardiac dysfunction in animal models of cachexia and heart failure with reduced ejection fraction (HFrEF). So far, no data exist on leucine supplementation on cardiac function in HFpEF. Thus, the current study aimed to investigate the effect of leucine supplementation on myocardial function and key signaling pathways in an established HFpEF rat model. Female ZSF1 rats were randomized into three groups: Control (untreated lean rats), HFpEF (untreated obese rats), and HFpEF_Leu (obese rats receiving standard chow enriched with 3% leucine). Leucine supplementation started at 20 weeks of age after an established HFpEF was confirmed in obese rats. In all animals, cardiac function was assessed by echocardiography at baseline and throughout the experiment. At the age of 32 weeks, hemodynamics were measured invasively, and myocardial tissue was collected for assessment of mitochondrial function and for histological and molecular analyses. Leucine had already improved diastolic function after 4 weeks of treatment. This was accompanied by improved hemodynamics and reduced stiffness, as well as by reduced left ventricular fibrosis and hypertrophy. Cardiac mitochondrial respiratory function was improved by leucine without alteration of the cardiac mitochondrial content. Lastly, leucine supplementation suppressed the expression and nuclear localization of HDAC4 and was associated with Protein kinase A activation. Our data show that leucine supplementation improves diastolic function and decreases remodeling processes in a rat model of HFpEF. Beneficial effects were associated with HDAC4/TGF-β1/Collagenase downregulation and indicate a potential use in the treatment of HFpEF.

Transforming growth factor-β and bone morphogenetic protein signaling pathways in pathological cardiac hypertrophy

Pathological cardiac hypertrophy (referred to as cardiac hypertrophy) is a maladaptive response of the heart to a variety of pathological stimuli, and cardiac hypertrophy is an independent risk factor for heart failure and sudden death. Currently, the treatments for cardiac hypertrophy are limited to improving symptoms and have little effect. Elucidation of the developmental process of cardiac hypertrophy at the molecular level and the identification of new targets for the treatment of cardiac hypertrophy are crucial. In this review, we summarize the research on multiple active substances related to the pathogenesis of cardiac hypertrophy and the signaling pathways involved and focus on the role of transforming growth factor-β (TGF-β) and bone morphogenetic protein (BMP) signaling in the development of cardiac hypertrophy and the identification of potential targets for molecular intervention. We aim to identify important signaling molecules with clinical value and hope to help promote the precise treatment of cardiac hypertrophy and thus improve patient outcomes.

Role of Pericytes in Cardiomyopathy-Associated Myocardial Infarction Revealed by Multiple Single-Cell Sequencing Analysis

Acute myocardial infarction (AMI) is one of the leading causes of cardiovascular death worldwide. AMI with cardiomyopathy is accompanied by a poor long-term prognosis. However, limited studies have focused on the mechanism of cardiomyopathy associated with AMI. Pericytes are important to the microvascular function in the heart, yet little attention has been paid to their function in myocardial infarction until now. In this study, we integrated single-cell data from individuals with cardiomyopathy and myocardial infarction (MI) GWAS data to reveal the potential function of pericytes in cardiomyopathy-associated MI. We found that pericytes were concentrated in the left atrium and left ventricle tissues. DLC1/GUCY1A2/EGFLAM were the top three uniquely expressed genes in pericytes (p < 0.05). The marker genes of pericytes were enriched in renin secretion, vascular smooth muscle contraction, gap junction, purine metabolism, and diabetic cardiomyopathy pathways (p < 0.05). Among these pathways, the renin secretion and purine metabolism pathways were also found in the process of MI. In cardiomyopathy patients, the biosynthesis of collagen, modulating enzymes, and collagen formation were uniquely negatively regulated in pericytes compared to other cell types (p < 0.05). COL4A2/COL4A1/SMAD3 were the hub genes in pericyte function involved in cardiomyopathy and AMI. In conclusion, this study provides new evidence about the importance of pericytes in the pathogenesis of cardiomyopathy-associated MI. DLC1/GUCY1A2/EGFLAM were highly expressed in pericytes. The hub genes COL4A2/COL4A1/SMAD3 may be potential research targets for cardiomyopathy-associated MI.

Systematic in vivo candidate evaluation uncovers therapeutic targets for LMNA dilated cardiomyopathy and risk of Lamin A toxicity

BACKGROUND

Dilated cardiomyopathy (DCM) is a severe, non-ischemic heart disease which ultimately results in heart failure (HF). Decades of research on DCM have revealed diverse aetiologies. Among them, familial DCM is the major form of DCM, with pathogenic variants in LMNA being the second most common form of autosomal dominant DCM. LMNA DCM is a multifactorial and complex disease with no specific treatment thus far. Many studies have demonstrated that perturbing candidates related to various dysregulated pathways ameliorate LMNA DCM. However, it is unknown whether these candidates could serve as potential therapeutic targets especially in long term efficacy.

METHODS

We evaluated 14 potential candidates including Lmna gene products (Lamin A and Lamin C), key signaling pathways (Tgfβ/Smad, mTor and Fgf/Mapk), calcium handling, proliferation regulators and modifiers of LINC complex function in a cardiac specific Lmna DCM model. Positive candidates for improved cardiac function were further assessed by survival analysis. Suppressive roles and mechanisms of these candidates in ameliorating Lmna DCM were dissected by comparing marker gene expression, Tgfβ signaling pathway activation, fibrosis, inflammation, proliferation and DNA damage. Furthermore, transcriptome profiling compared the differences between Lamin A and Lamin C treatment.

RESULTS

Cardiac function was restored by several positive candidates (Smad3, Yy1, Bmp7, Ctgf, aYAP1, Sun1, Lamin A, and Lamin C), which significantly correlated with suppression of HF/fibrosis marker expression and cardiac fibrosis in Lmna DCM. Lamin C or Sun1 shRNA administration achieved consistent, prolonged survival which highly correlated with reduced heart inflammation and DNA damage. Importantly, Lamin A treatment improved but could not reproduce long term survival, and Lamin A administration to healthy hearts itself induced DCM. Mechanistically, we identified this lapse as caused by a dose-dependent toxicity of Lamin A, which was independent from its maturation.

CONCLUSIONS

In vivo candidate evaluation revealed that supplementation of Lamin C or knockdown of Sun1 significantly suppressed Lmna DCM and achieve prolonged survival. Conversely, Lamin A supplementation did not rescue long term survival and may impart detrimental cardiotoxicity risk. This study highlights a potential of advancing Lamin C and Sun1 as therapeutic targets for the treatment of LMNA DCM.

Retinoid X receptor agonists alleviate fibroblast activation and post-infarction cardiac remodeling via inhibition of TGF-β1/Smad pathway

Retinoid X receptor (RXR), particularly RXRα, has been implicated in cardiovascular diseases. However, the functional role of RXR activation in myocardial infarction (MI) remains unclear. This study aimed to determine the effects of RXR agonists on MI and to dissect the underlying mechanisms. Sprague-Dawley (SD) rats were subjected to MI and then treated (once daily for 4 weeks) with either RXR agonist bexarotene (10 or 30 mg/kg body weight) or vehicle. Heart function was determined using echocardiography and cardiac hemodynamic measurements. Four weeks post MI, myocardial tissues were collected to evaluate cardiac remodeling. Primary cardiac fibroblasts (CFs) were treated with or without RXR ligand 9-cis-RA followed by stimulation with TGF-β1. Immunoblot, immunofluorescence, and co-immunoprecipitation were performed to elucidate the regulatory role of RXR agonists in TGF-β1/Smad signaling. In vivo treatment with Bexarotene moderately affects systemic inflammation and apoptosis and ameliorated left ventricular dysfunction after MI in rat model. In contrast, bexarotene significantly inhibited post-MI myocardial fibrosis. Immunoblot analysis of heart tissue homogenates from MI rats revealed that bexarotene regulated the activation of the TGF-β1/Smad signaling pathway. In vitro, 9-cis-RA inhibited the TGF-β1-induced proliferation and collagen production of CFs. Importantly, upon activation by 9-cis-RA, RXRα interacted with p-Smad2 in cytoplasm, inhibiting the TGF-β1-induced nuclear translocation of p-Smad2, thereby negatively regulating TGF-β1/Smad signaling and attenuating the fibrotic response of CFs. These findings suggest that RXR agonists ameliorate post-infarction myocardial fibrosis, maladaptive remodeling, and heart dysfunction via attenuation of fibrotic response in CFs through inhibition of the TGF-β1/Smad pathway activation.

1821-2021: Contributions of physicians and researchers of Greek descent in the advancement of clinical and experimental cardiology and cardiac surgery

While the role of Greeks in the development of early western medicine is well-known and appreciated, the contributions of modern Greek medical practitioners are less known and often overlooked. On the occasion of the 200-year anniversary of the Greek War of Independence, this review article sheds light onto the achievements of modern scientists of Greek descent in the development of cardiology, cardiac surgery, and cardiovascular research, through a short history of the development of these fields and of the related institutions in Greece. In the last decades, the Greek cardiology and Cardiac Surgery communities have been active inside and outside Greece and have a remarkable presence internationally, particularly in the United States. This article highlights the ways in which Greek cardiology and cardiovascular research has been enriched by absorbing knowledge produced in international medical centers, academic institutes and pharmaceutical industries in which generations of Greek doctors and researchers trained prior to their return to the homeland; it also highlights the achievements of medical practitioners and researchers of Greek descent who excelled abroad, producing ground-breaking work that has left a permanent imprint on global medicine.

The Microenvironment of the Pathogenesis of Cardiac Hypertrophy

Pathological cardiac hypertrophy is a key risk factor for the development of heart failure and predisposes individuals to cardiac arrhythmia and sudden death. While physiological cardiac hypertrophy is adaptive, hypertrophy resulting from conditions comprising hypertension, aortic stenosis, or genetic mutations, such as hypertrophic cardiomyopathy, is maladaptive. Here, we highlight the essential role and reciprocal interactions involving both cardiomyocytes and non-myocardial cells in response to pathological conditions. Prolonged cardiovascular stress causes cardiomyocytes and non-myocardial cells to enter an activated state releasing numerous pro-hypertrophic, pro-fibrotic, and pro-inflammatory mediators such as vasoactive hormones, growth factors, and cytokines, i.e., commencing signaling events that collectively cause cardiac hypertrophy. Fibrotic remodeling is mediated by cardiac fibroblasts as the central players, but also endothelial cells and resident and infiltrating immune cells enhance these processes. Many of these hypertrophic mediators are now being integrated into computational models that provide system-level insights and will help to translate our knowledge into new pharmacological targets. This perspective article summarizes the last decades' advances in cardiac hypertrophy research and discusses the herein-involved complex myocardial microenvironment and signaling components.

Potential molecular mechanism underlying cardiac fibrosis in diabetes mellitus: a narrative review

BACKGROUND

Diabetes mellitus (DM) is among the most common risk factors for cardiovascular disease in the world with prevalence of more than 500 million population in 2021. Cardiac fibrosis with its complex process has been hypothesized as one of the mechanisms explaining development of heart failure in diabetic patients. Recently, the biomolecular mechanism of cardiac fibrosis in the hyperglycemia setting has been focusing around transforming growth factor β-1 (TGFβ-1) as a major factor. However, there is interplay role of several factors including microRNAs (miRNAs) which acts as a potential regulator of cardiac fibrosis connected with TGFβ-1. In this review, we explored interplay role of several factors including microRNAs which acts as a potential regulator of cardiac fibrosis connected with TGFβ-1 in diabetes mellitus. This narrative review included articles from the PubMed and Science Direct databases published in the last 10 years (2012-2022).

MAIN TEXT

In diabetic patients, excessive activation of myofibroblasts occurs and triggers pro-collagen to convert into mature collagen to fill the cardiac interstitial space resulting in a pathological process of extracellular matrix remodeling. The balance between matrix metalloproteinase (MMP) and its inhibitor (tissue inhibitor of metalloproteinase, TIMP) is crucial in degradation of the extracellular matrix. Diabetes-related cardiac fibrosis is modulated by increasing level of TGF-β1 mediated by cellular components, including cardiomyocyte and non-cardiomyocyte cells involving fibroblasts, vascular pericytes smooth muscle cells, endothelial cells, mast cells, macrophages, and dendritic cells. Several miRNAs such as miR-21, miR-9, miR-29, miR-30d, miR-144, miR-34a, miR-150, miR-320, and miR-378 are upregulated in diabetic cardiomyopathy. TGF-β1, together with inflammatory cytokines, oxidative stress, combined sma and the mothers against decapentaplegic (smad) protein, mitogen-activated protein kinase (MAPK), and microRNAs, is interconnectedly involved in extracellular matrix production and fibrotic response. In this review, we explored interplay role of several factors including microRNAs which acts as a potential regulator of cardiac fibrosis connected with TGFβ-1 in diabetes mellitus.

CONCLUSIONS

Long-term hyperglycemia activates cardiac fibroblast via complex processes involving TGF-β1, miRNA, inflammatory chemokines, oxidative stress, smad, or MAPK pathways. There is increasing evidence of miRNA's roles lately in modulating cardiac fibrosis.

Single-Dose Treatment with Rapamycin Preserves Post-Ischemic Cardiac Function through Attenuation of Fibrosis and Inflammation in Diabetic Rabbit

Robust activation of mTOR (mammalian target of rapamycin) signaling in diabetes exacerbates myocardial injury following lethal ischemia due to accelerated cardiomyocyte death with cardiac remodeling and inflammatory responses. We examined the effect of rapamycin (RAPA, mTOR inhibitor) on cardiac remodeling and inflammation following myocardial ischemia/reperfusion (I/R) injury in diabetic rabbits. Diabetic rabbits (DM) were subjected to 45 min of ischemia and 10 days of reperfusion by inflating/deflating a previously implanted hydraulic balloon occluder. RAPA (0.25 mg/kg, i.v.) or DMSO (vehicle) was infused 5 min before the onset of reperfusion. Post-I/R left ventricular (LV) function was assessed by echocardiography and fibrosis was evaluated by picrosirius red staining. Treatment with RAPA preserved LV ejection fraction and reduced fibrosis. Immunoblot and real-time PCR revealed that RAPA treatment inhibited several fibrosis markers (TGF-β, Galectin-3, MYH, p-SMAD). Furthermore, immunofluorescence staining revealed the attenuation of post-I/R NLRP3-inflammasome formation with RAPA treatment as shown by reduced aggregation of apoptosis speck-like protein with a caspase recruitment domain and active-form of caspase-1 in cardiomyocytes. In conclusion, our study suggests that acute reperfusion therapy with RAPA may be a viable strategy to preserve cardiac function with the alleviation of adverse post-infarct myocardial remodeling and inflammation in diabetic patients.

Upregulation of glycolytic enzyme PFKFB3 by deubiquitinase OTUD4 promotes cardiac fibrosis post myocardial infarction

Metabolic dysregulations have emerged as a major mediator of cardiovascular disorders and fibrotic diseases. Metabolic reprogramming contributes a lot to cardiac fibroblast activation and cardiac fibrosis post-myocardial infarction (MI), yet the mechanism remains incompletely understood. Our work aimed to determine whether or not glycolytic reprogramming, regulated by phosphofructokinase-2/fructose-2,6-bisphosphatase 3 (PFKFB3), is a therapeutic target for alleviating post-MI cardiac fibrosis. Here, we showed that cardiac fibroblasts displayed cell energy phenotype toward augmented glycolysis in response to transforming growth factor-beta 1 (TGF-β1), evidenced by significant extracellular acidification rate (ECAR) increase and lactate accumulation. The expression of glycolytic enzyme PFKFB3, a master activator of glycolysis, was up-regulated in TGF-β1-treated cardiac fibroblasts and in cardiac fibroblasts of post-MI mice. Pharmacological inhibition of PFKFB3 by 3PO diminished TGF-β1-mediated profibrotic phenotypes, attenuated cardiac fibrosis, and preserved cardiac functions in post-MI mice. Meanwhile, the genetic inhibition of PFKFB3 decreased the cardiac fibroblast activation and reversed the differentiated phenotypes in vitro and in vivo. Mechanistically, we identified deubiquitinase OTUD4 as a new binding protein of PFKFB3, and their interaction blocked PFKFB3 degradation via OTUD4-mediated deubiquitylation. Taken together, this work characterized a key role for PFKFB3 in cardiac fibroblast activation and suggested that inhibiting PFKFB3-involved glycolysis is an alternative way to alleviate post-MI cardiac fibrosis. KEY MESSAGES: PFKFB3, a master activator of glycolysis, was highly expressed in ischemic cardiac fibroblasts to enhance cardiac fibrosis The deubiquitinase OTUD4 was identified as a new binding protein of PFKFB3 TGF-β1 blunted the ubiquitination-mediated degradation of PFKFB3 via OTUD4-mediated deubiquitylation Blockade of PFKFB3 contributed to ameliorating ischemia-induced cardiac fibrosis.

The phagocytic role of macrophage following myocardial infarction

Myocardial infarction (MI) is one of the cardiovascular diseases with high morbidity and mortality. MI causes large amounts of apoptotic and necrotic cells that need to be efficiently and instantly engulfed by macrophage to avoid second necrosis. Phagocytic macrophages can dampen or resolve inflammation to protect infarcted heart. Phagocytosis of macrophages is modulated by various factors including proteins, receptors, lncRNA and cytokines. A better understanding of mechanisms in phagocytosis will be beneficial to regulate macrophage phagocytosis capability towards a desired direction in cardioprotection after MI. In this review, we describe the phagocytosis effect of macrophages and summarize the latest reported signals regulating phagocytosis after MI, which will provide a new thinking about phagocytosis-dependent cardiac protection after MI.

Metformin: evidence from preclinical and clinical studies for potential novel applications in cardiovascular disease

INTRODUCTION

For a long time, metformin has been the first-line treatment for glycaemic control in type 2 diabetes, however, the results of recent cardiovascular outcome trials of sodium-glucose co-transporter 2 inhibitors and glucagon-like peptide 1 receptor agonists have caused many to question metformin's position in the guidelines. Although there are several plausible mechanisms by which metformin might have beneficial cardiovascular effects, for example its anti-inflammatory effects and metabolic properties, and numerous observational data suggesting improved cardiovascular outcomes with metformin use, the main randomised clinical trial data for metformin was published over 20 years ago. Nevertheless, the overwhelming majority of participants in contemporary type 2 diabetes trials were prescribed metformin.

AREAS COVERED

In this review we will summarise the potential mechanisms of cardiovascular benefit with metformin, before discussing clinical data in individuals with or without diabetes.

EXPERT OPINION

Metformin may have some cardiovascular benefit in patients with and without diabetes, however the majority of clinical trials were small and are before the use SGLT2 inhibitors and GLP1-RAs. Larger contemporary randomised trials with metformin evaluating its cardiovascular benefit are warranted.

Signaling Pathways and Potential Therapeutic Strategies in Cardiac Fibrosis

Cardiac fibrosis constitutes irreversible necrosis of the heart muscle as a consequence of different acute (myocardial infarction) or chronic (diabetes, hypertension, …) diseases but also due to genetic alterations or aging. Currently, there is no curative treatment that is able to prevent or attenuate this phenomenon that leads to progressive cardiac dysfunction and life-threatening outcomes. This review summarizes the different targets identified and the new strategies proposed to fight cardiac fibrosis. Future directions, including the use of exosomes or nanoparticles, will also be discussed.

Evaluation of Fibrosis Markers as a Potential Method for Diagnosing Non-Obstructive Coronary Artery Disease in Patients with Stable Coronary Artery Disease

Aim. To study the levels of fibrosis markers in patients with stable coronary artery disease (CAD) and various types of coronary artery (CA) lesions (obstructive and non-obstructive), to identify possible differences for diagnosing the types of coronary obstruction.

Material and methods. The observational study included three groups of patients: with non-obstructive (main group, coronary artery stenosis <50%; n=20) and obstructive (comparison group, hemodynamically significant coronary artery stenosis according to the results of coronary angiography; n=20) CAD and healthy volunteers (control group; n=40). Transforming growth factor beta 1 (TGF-β1) and matrix metalloproteinase 9 (MMP-9) levels were measured in plasma by enzyme immunoassay. According to the results of echocardiography, all patients included in the study were divided into four groups depending on the type of myocardial remodeling.

Results. TGF-β1 levels were significantly higher in patients with obstructive CAD (p=0.008) than in patients with non-obstructive CAD and healthy volunteers (p <0.001). There were no significant differences between the main and control groups (p>0.05). There were no statistically significant differences in TGF-β1 levels depending on the type of left ventricular remodeling (p=0.139). The maximum level of MMP-9 was in the group with obstructive coronary disease and significantly differed from the main group (p <0.001) and the control group (p=0.04).

Conclusio. The maximum levels of TGF-β1 and MMP-9 were found in the group with obstructive coronary artery disease. The levels of these biomarkers in the main group were statistically different from the values obtained in the control group. Thus, considering the pathogenesis of the development of non-obstructive CAD, the use of fibrosis markers TGF-β1 and MMP-9 may be promising for diagnosing the severity of CA obstruction.

Hypertrophic and fibrotic human PKD hearts are associated with macrophage infiltration and abnormal TGF-β1 signaling

Autosomal dominant polycystic kidney disease (PKD) is a hereditary kidney disorder which can affect cardiovascular system. Cardiac hypertrophy and cardiomyopathy in PKD have been reported by echocardiography analyses, but histopathology analyses of human PKD hearts have never been examined. The current studies evaluated human heart tissues from five subjects without PKD (non-PKD) and five subjects with PKD. Our histopathology data of human PKD hearts showed an increased extracellular matrix associated with cardiac hypertrophy and fibrosis. Hypertrophy- and fibrosis-associated pathways involving abnormal cardiac structure were next analyzed. We found that human PKD myocardium was infiltrated by inflammatory macrophage M1 and M2; expression of transforming growth factor (TGF-β₁) and its receptor were upregulated with overexpression of pSmad3 and β-catenin. Because patients with PKD have an abnormal kidney function that could potentially affect heart structure, we used a heart-specific PKD mouse model to validate that cardiac hypertrophy and fibrosis were independent from polycystic kidney. In summary, our data show that hearts from human PKD were characterized by hypertrophy, interstitial fibrosis, perivascular fibrosis, and conduction system fibrosis with upregulated TGF-β₁ and its receptor. We suggest that such structural abnormalities may predispose to systolic and diastolic cardiac dysfunction in the PKD myocardium.

12-O-tetradecanoylphorbol-13-acetate Reduces Activation of Hepatic Stellate Cells by Inhibiting the Hippo Pathway Transcriptional Coactivator YAP

Although protein kinase C (PKC) regulates various biological activities, including cell proliferation, differentiation, migration, tissue remodeling, gene expression, and cell death, the antifibrotic effect of PKC in myofibroblasts is not fully understood. We investigated whether 12-O-tetradecanoylphorbol-13-acetate (TPA), a PKC activator, reduced the activation of hepatic stellate cells (HSCs) and explored the involvement of the Hippo pathway transcriptional coactivator YAP. We analyzed the effect of TPA on the proliferation and expression of α-smooth muscle actin (SMA) in the LX-2 HSC line. We also analyzed the phosphorylation of the Hippo pathway molecules YAP and LATS1 and investigated YAP nuclear translocation. We examined whether Gö 6983, a pan-PKC inhibitor, restored the TPA-inhibited activities of HSCs. Administration of TPA decreased the growth rate of LX-2 cells and inhibited the expression of α-SMA and collagen type I alpha 1 (COL1A1). In addition, TPA induced phosphorylation of PKCδ, LATS1, and YAP and inhibited the nuclear translocation of YAP compared with the control. These TPA-induced phenomena were mostly ameliorated by Gö 6983. Our results indicate that PKCδ exerts an antifibrotic effect by inhibiting the Hippo pathway in HSCs. Therefore, PKCδ and YAP can be used as therapeutic targets for the treatment of fibrotic diseases.

Transplantation of Skeletal Muscle-Derived Sca-1+/PW1+/Pax7- Interstitial Cells (PICs) Improves Cardiac Function and Attenuates Remodeling in Mice Subjected to Myocardial Infarction

We have previously shown that skeletal muscle-derived Sca-1+/PW1+/Pax7- interstitial cells (PICs) are multi-potent and enhance endogenous repair and regeneration. Here, we investigated the regenerative potential of PICs following intramyocardial transplantation in mice subjected to an acute myocardial infarction (MI). MI was induced through the ligation of the left anterior descending coronary artery in 8-week old male C57BL/6 mice. 5 × 105 eGFP-labelled PICs (MI + PICs; n = 7) or PBS (MI-PBS; n = 7) were injected intramyocardially into the border zone. Sham mice (n = 8) were not subjected to MI, or the transplantation of PICs or PBS. BrdU was administered via osmotic mini-pump for 14 days. Echocardiography was performed prior to surgery (baseline), and 1-, 3- and 6-weeks post-MI and PICs transplantation. Mice were sacrificed at 6 weeks post-MI + PICs transplantation, and heart sections were analysed for fibrosis, hypertrophy, engraftment, proliferation, and differentiation of PICs. A significant (p < 0.05) improvement in ejection fraction (EF) and fractional shortening was observed in the MI-PICs group, compared to MI + PBS group at 6-weeks post MI + PICs transplantation. Infarct size/fibrosis of the left ventricle significantly (p < 0.05) decreased in the MI-PICs group (14.0 ± 2.5%), compared to the MI-PBS group (32.8 ± 2.2%). Cardiomyocyte hypertrophy in the border zone significantly (p < 0.05) decreased in the MI-PICs group compared to the MI-PBS group (330.0 ± 28.5 µM2 vs. 543.5 ± 26.6 µm2), as did cardiomyocyte apoptosis (0.6 ± 0.9% MI-PICs vs. 2.8 ± 0.8% MI-PBS). The number of BrdU+ cardiomyocytes was significantly (p < 0.05) increased in the infarct/border zone of the MI-PICs group (7.0 ± 3.3%), compared to the MI-PBS group (1.7 ± 0.5%). The proliferation index (total BrdU+ cells) was significantly increased in the MI-PICs group compared to the MI-PBS group (27.0 ± 3.4% vs. 7.6 ± 1.0%). PICs expressed and secreted pro-survival and reparative growth factors, supporting a paracrine effect of PICs during recovery/remodeling. Skeletal muscle-derived PICs show significant reparative potential, attenuating cardiac remodelling following transplantation into the infarcted myocardium. PICs can be easily sourced from skeletal muscle and therefore show promise as a potential cell candidate for supporting the reparative and regenerative effects of cell therapies.

Unveiling the Vital Role of Long Non-Coding RNAs in Cardiac Oxidative Stress, Cell Death, and Fibrosis in Diabetic Cardiomyopathy

Diabetes mellitus is a burdensome public health problem. Diabetic cardiomyopathy (DCM) is a major cause of mortality and morbidity in diabetes patients. The pathogenesis of DCM is multifactorial and involves metabolic abnormalities, the accumulation of advanced glycation end products, myocardial cell death, oxidative stress, inflammation, microangiopathy, and cardiac fibrosis. Evidence suggests that various types of cardiomyocyte death act simultaneously as terminal pathways in DCM. Long non-coding RNAs (lncRNAs) are a class of RNA transcripts with lengths greater than 200 nucleotides and no apparent coding potential. Emerging studies have shown the critical role of lncRNAs in the pathogenesis of DCM, along with the development of molecular biology technologies. Therefore, we summarize specific lncRNAs that mainly regulate multiple modes of cardiomyopathy death, oxidative stress, and cardiac fibrosis and provide valuable insights into diagnostic and therapeutic biomarkers and strategies for DCM.

Smad3 promotes adverse cardiovascular remodeling and dysfunction in doxorubicin-treated hearts

Many anticancer therapies cause serious cardiovascular complications that degrade quality of life and cause early mortality in treated patients. Specifically, doxorubicin is known as an effective anticancer agent that causes cardiomyopathy in treated patients. There has been growing interest in defining the role of endothelial cells in cardiac damage by doxorubicin. We have shown in the present study that endothelial nuclei accumulate more intravenously administered doxorubicin than other cardiac cell types. Doxorubicin enhanced cardiac production of the transforming growth factor-β (TGF-β) ligands and nuclear translocation of phospho-Smad3 in both cultured and in vivo cardiac endothelial cells. To examine the role of the TGF-β/mothers against decapentaplegic homolog 3 (Smad3) pathway in cardiac damage by doxorubicin, we used both Smad3 shRNA stable endothelial cell lines and Smad3-knockout mice. We demonstrated using endothelial transcriptome analysis that upregulation of the TGF-β and inflammatory cytokine/cytokine receptor pathways, as well as suppression of cell cycle and angiogenesis by doxorubicin, were alleviated in Smad3-deficient endothelial cells. The results of transcriptomic analysis were validated using qPCR, immunoblotting, and ex vivo aortic ring sprouting assays. Similarly, increased cardiac expression of cytokines and chemokines observed in treated wild-type mice was diminished in treated Smad3-knockout animals. We also detected increased end-diastolic diameter and depressed systolic function in doxorubicin-treated wild-type but not Smad3-knockout mice. This work provides evidence for the critical role of the canonical TGF-β/Smad3 pathway in cardiac damage by doxorubicin.NEW & NOTEWORTHY Microvascular endothelial cells in the heart accumulate more intravenously administered doxorubicin than nonendothelial cardiac cell types. The treatment enhanced the TGF-β/Smad3 pathway and elicited endothelial cell senescence and inflammatory responses followed by adverse cardiac remodeling and dysfunction in wild-type but not Smad3-deficient animals. Our study suggests that the TGF-β/Smad3 pathway contributes to the development of doxorubicin cardiomyopathy and the potential value of novel approaches to ameliorate cardiotoxicity by targeting the Smad3 transcription factor.

Exploring the cardiac ECM during fibrosis: A new era with next-gen proteomics

Extracellular matrix (ECM) plays a critical role in maintaining elasticity in cardiac tissues. Elasticity is required in the heart for properly pumping blood to the whole body. Dysregulated ECM remodeling causes fibrosis in the cardiac tissues. Cardiac fibrosis leads to stiffness in the heart tissues, resulting in heart failure. During cardiac fibrosis, ECM proteins get excessively deposited in the cardiac tissues. In the ECM, cardiac fibroblast proliferates into myofibroblast upon various kinds of stimulations. Fibroblast activation (myofibroblast) contributes majorly toward cardiac fibrosis. Other than cardiac fibroblasts, cardiomyocytes, epithelial/endothelial cells, and immune system cells can also contribute to cardiac fibrosis. Alteration in the expression of the ECM core and ECM-modifier proteins causes different types of cardiac fibrosis. These different components of ECM culminated into different pathways inducing transdifferentiation of cardiac fibroblast into myofibroblast. In this review, we summarize the role of different ECM components during cardiac fibrosis progression leading to heart failure. Furthermore, we highlight the importance of applying mass-spectrometry-based proteomics to understand the key changes occurring in the ECM during fibrotic progression. Next-gen proteomics studies will broaden the potential to identify key targets to combat cardiac fibrosis in order to achieve precise medicine-development in the future.

Adverse effect signature extraction and prediction for drugs treating COVID-19

Given the considerable cost of drug discovery, drug repurposing is becoming attractive as it can effectively shorten the development timeline and reduce the development cost. However, most existing drug-repurposing methods omitted the heterogeneous health conditions of different COVID-19 patients. In this study, we evaluated the adverse effect (AE) profiles of 106 COVID-19 drugs. We extracted four AE signatures to characterize the AE distribution of 106 COVID-19 drugs by non-negative matrix factorization (NMF). By integrating the information from four distinct databases (AE, bioassay, chemical structure, and gene expression information), we predicted the AE profiles of 91 drugs with inadequate AE feedback. For each of the drug clusters, discriminant genes accounting for mechanisms of different AE signatures were identified by sparse linear discriminant analysis. Our findings can be divided into three parts. First, drugs abundant with AE-signature 1 (for example, remdesivir) should be taken with caution for patients with poor liver, renal, or cardiac functions, where the functional genes accumulate in the RHO GTPases Activate NADPH Oxidases pathway. Second, drugs featuring AE-signature 2 (for example, hydroxychloroquine) are unsuitable for patients with vascular disorders, with relevant genes enriched in signal transduction pathways. Third, drugs characterized by AE signatures 3 and 4 have relatively mild AEs. Our study showed that NMF and network-based frameworks contribute to more precise drug recommendations.

Gentiopicroside alleviates cardiac inflammation and fibrosis in T2DM rats through targeting Smad3 phosphorylation

BACKGROUND

Cardiac fibrosis is a major structural change observed in the heart of patients with type 2 diabetes mellitus (T2DM), ultimately resulting in heart failure (HF). Suppression of inflammation is an effective therapeutic strategy for treating cardiac fibrosis and HF. Gentiopicroside (GPS), the primary component of Gentiana manshurica Kitagawa, possess potent anti-inflammatory activity. However, its cardioprotective role remains elusive.

PURPOSE

We explored the potential cardioprotective role of GPS in T2DM rats and its underlying mechanisms.

METHODS

T2DM rats built by high-fat diet and streptozotocin were orally administered 25, 50, or 100 mg/kg GPS, daily for 8 weeks. The positive control drug was Metformin (200 mg/kg/day). Primary cardiac fibroblasts (CFs) were induced by high glucose (30 mM) and subsequently treated with GPS (100 μM). Cardiac function and pathological changes were analyzed using echocardiography and histological staining. Potential targets of GPS were predicted using Molecular docking. Real-time PCR as well as western blotting were applied to verify the expression of objective genes.

RESULTS

All three doses reduced fasting blood glucose levels, but only 50 and 100 mg/kg GPS improved cardiac function and alleviated inflammation and fibrosis in T2DM rats. GPS (100 mg/kg) exhibited a better effect, similar to that of metformin. Mechanistically, binding between GPS and the MH2 domain of Smad3 blocked high glucose-induced Smad3 phosphorylation, thus attenuating inflammation, oxidative stress, and activation in CFs.

CONCLUSION

We, for the first time, demonstrated that GPS improved cardiac function in T2DM rats and elucidated the underlying mechanism through which GPS targeted Smad3 phosphorylation to suppress inflammation and activation in CFs, thereby revealing the potential application of GPS in HF therapy.

Transcriptional plasticity of fibroblasts in heart disease

Cardiac fibroblasts play an essential role in maintaining the structural framework of the heart. Upon stress, fibroblasts undergo a cell state transition to activated fibroblasts (also referred to as myofibroblasts), a highly synthetic cell type that proliferates, migrates, and secrets both extracellular matrix as well as signaling factors that can modulate cellular crosstalk [J. Clin. Invest. 132, e148554]. Activated fibroblasts are critical regulators of cardiac wound healing after injury, but their excessive and persistent activation promote tissue fibrosis, a hallmark feature of the pathological remodeling of the heart. While much of the previous work in cardiac fibroblast biology has focused on the role of canonical signaling pathways or components of the extracellular matrix, recent efforts have been focused on deciphering the gene regulatory principles governing fibroblast activation. A better understanding of the molecular mechanisms that trigger and sustain the fibrotic process in heart disease has the potential to accelerate the development of therapies that specifically target the cardiac activated fibroblasts, which are at the moment unavailable. This concise review focuses on the mechanisms underlying the chromatin and transcriptional regulation of cardiac fibroblast activation. We discuss recent work from our group and others in this space, highlighting the application of single-cell genomics in the characterization of fibroblast function and diversity, and provide an overview on the prospects of targeting cardiac fibroblasts in heart disease and the associated challenges.

Transcriptional regulation of cardiac fibroblast phenotypic plasticity

Cardiac fibroblasts play critical roles in the maintenance of cardiac structure and the response to cardiac insult. Extracellular matrix deposition by activated resident cardiac fibroblasts, called myofibroblasts, is an essential wound healing response. However, persistent fibroblast activation contributes to pathological fibrosis and cardiac chamber stiffening, which can cause diastolic dysfunction, heart failure, and initiate lethal arrhythmias. The dynamic and phenotypically plastic nature of cardiac fibroblasts is governed in part by the transcriptional regulation of genes encoding extracellular matrix molecules. Understanding how fibroblasts integrate various biomechanical cues into a precise transcriptional response may uncover therapeutic strategies to prevent fibrosis. Here, we provide an overview of the recent literature on transcriptional control of cardiac fibroblast plasticity and fibrosis, with a focus on canonical and non-canonical TGF-β signaling, biomechanical regulation of Hippo/YAP and Rho/MRTF signaling, and metabolic and epigenetic control of fibroblast activation.

[Integrins in cardiac fibrosis]

For the last 20 years, integrins have been a therapeutic target of interest in the treatment of fibrotic diseases, particularly regarding the integrins of the αV family. Initially developed as anti-cancer drugs but with modest benefits, inhibitors of integrins (such as the anti-αV cilengitide) have shown interesting anti-fibrotic effects in different organs including the heart. Cardiac fibrosis is defined as an accumulation of stiff extracellular matrix in the myocardium, and ultimately leads to heart failure, one of the leading causes of mortality worldwide. Understanding the determinants of cardiac fibrosis and the involvement of integrins is a major matter of public health. This review presents the current knowledge on the different types of cardiac fibrosis and their etiologies, and report on first data supporting specific integrin inhibition therapy as a novel anti-fibrotic strategy, in particular to treat cardiac fibrosis.

Bellidifolin Inhibits SRY-Related High Mobility Group-Box Gene 9 to Block TGF-β Signalling Activation to Ameliorate Myocardial Fibrosis

Myocardial fibrosis is the main morphological change of ventricular remodelling caused by cardiovascular diseases, mainly manifested due to the excessive production of collagen proteins. SRY-related high mobility group-box gene 9 (SOX9) is a new target regulating myocardial fibrosis. Bellidifolin (BEL), the active component of G. acuta, can prevent heart damage. However, it is unclear whether BEL can regulate SOX9 to alleviate myocardial fibrosis. The mice were subjected to isoproterenol (ISO) to establish myocardial fibrosis, and human myocardial fibroblasts (HCFs) were activated by TGF-β1 in the present study. The pathological changes of cardiac tissue were observed by HE staining. Masson staining was applied to reveal the collagen deposition in the heart. The measurement for expression of fibrosis-related proteins, SOX9, and TGF-β1 signalling molecules adopted Western blot and immunohistochemistry. The effects of BEL on HCFs, activity were detected by CCK-8. The result showed that BEL did not affect cell viability. And, the data indicated that BEL inhibited the elevations in α-SMA, Collagen I, and Collagen III by decreasing SOX9 expression. Additionally, SOX9 suppression by siRNA downregulated the TGF-β1 expression and prevented Smad3 phosphorylation, as supported by reducing the expression of α-SMA, Collagen I, and Collagen III. In vivo study verified that BEL ameliorated myocardial fibrosis by inhibiting SOX9. Therefore, BEL inhibited SOX9 to block TGF-β1 signalling activation to ameliorate myocardial fibrosis.

Signaling cascades in the failing heart and emerging therapeutic strategies

Chronic heart failure is the end stage of cardiac diseases. With a high prevalence and a high mortality rate worldwide, chronic heart failure is one of the heaviest health-related burdens. In addition to the standard neurohormonal blockade therapy, several medications have been developed for chronic heart failure treatment, but the population-wide improvement in chronic heart failure prognosis over time has been modest, and novel therapies are still needed. Mechanistic discovery and technical innovation are powerful driving forces for therapeutic development. On the one hand, the past decades have witnessed great progress in understanding the mechanism of chronic heart failure. It is now known that chronic heart failure is not only a matter involving cardiomyocytes. Instead, chronic heart failure involves numerous signaling pathways in noncardiomyocytes, including fibroblasts, immune cells, vascular cells, and lymphatic endothelial cells, and crosstalk among these cells. The complex regulatory network includes protein-protein, protein-RNA, and RNA-RNA interactions. These achievements in mechanistic studies provide novel insights for future therapeutic targets. On the other hand, with the development of modern biological techniques, targeting a protein pharmacologically is no longer the sole option for treating chronic heart failure. Gene therapy can directly manipulate the expression level of genes; gene editing techniques provide hope for curing hereditary cardiomyopathy; cell therapy aims to replace dysfunctional cardiomyocytes; and xenotransplantation may solve the problem of donor heart shortages. In this paper, we reviewed these two aspects in the field of failing heart signaling cascades and emerging therapeutic strategies based on modern biological techniques.

At the Intersection of Cardiology and Oncology: TGFβ as a Clinically Translatable Therapy for TNBC Treatment and as a Major Regulator of Post-Chemotherapy Cardiomyopathy

Triple-negative breast cancer (TNBC) is a subtype of breast cancer that accounts for the majority of breast cancer-related deaths due to the lack of specific targets for effective treatments. While there is immense focus on the development of novel therapies for TNBC treatment, a persistent and critical issue is the rate of heart failure and cardiomyopathy, which is a leading cause of mortality and morbidity amongst cancer survivors. In this review, we highlight mechanisms of post-chemotherapeutic cardiotoxicity exposure, evaluate how this is assessed clinically and highlight the transforming growth factor-beta family (TGF-β) pathway and its significance as a mediator of cardiomyopathy. We also highlight recent findings demonstrating TGF-β inhibition as a potent method to prevent cardiac remodeling, fibrosis and cardiomyopathy. We describe how dysregulation of the TGF-β pathway is associated with negative patient outcomes across 32 types of cancer, including TNBC. We then highlight how TGF-β modulation may be a potent method to target mesenchymal (CD44+/CD24-) and epithelial (ALDHhigh) cancer stem cell (CSC) populations in TNBC models. CSCs are associated with tumorigenesis, metastasis, relapse, resistance and diminished patient prognosis; however, due to plasticity and differential regulation, these populations remain difficult to target and continue to present a major barrier to successful therapy. TGF-β inhibition represents an intersection of two fields: cardiology and oncology. Through the inhibition of cardiomyopathy, cardiac damage and heart failure may be prevented, and through CSC targeting, patient prognoses may be improved. Together, both approaches, if successfully implemented, would target the two greatest causes of cancer-related morbidity in patients and potentially lead to a breakthrough therapy.

Daidzein suppresses TGF-β1-induced cardiac fibroblast activation via the TGF-β1/SMAD2/3 signaling pathway

Myocardial fibrosis is a concomitant bioprocess associated with many cardiovascular diseases (CVDs). Daidzein is an isoflavone that has been used for the treatment of CVDs. This study aimed to reveal its role in myocardial fibrosis. Our results indicate that daidzein had a nontoxic effect on cardiac fibroblasts and that TGF-β1 and TGFβRI levels were gradually decreased by daidzein in a dose-dependent manner. In the current study, we show that daidzein significantly inhibited TGF-β1-induced mRNA and protein expression of α-SMA, collagen I, and collagen III. Accordingly, immunofluorescence staining of α-SMA was performed. Daidzein also inhibited TGF-β1-induced cardiac fibroblast proliferation and migration. Mechanistically, daidzein inhibited the TGF-β/SMAD signaling pathway induced by TGF-β1 in cardiac fibroblasts. Additionally, daidzein ameliorated MI-induced cardiac dysfunction and cardiac fibrosis in vivo. Based on these findings, we conclude that daidzein reduces TGF-β1-induced cardiac fibroblast activation by partially regulating the TGF-β1/SMAD2/3 signaling pathway.

Therapeutic targets for cardiac fibrosis: from old school to next-gen

Cardiovascular diseases remain the leading cause of death worldwide, with pathological fibrotic remodeling mediated by activated cardiac myofibroblasts representing a unifying theme across etiologies. Despite the profound contributions of myocardial fibrosis to cardiac dysfunction and heart failure, there currently exist limited clinical interventions that effectively target the cardiac fibroblast and its role in fibrotic tissue deposition. Exploration of novel strategies designed to mitigate or reverse myofibroblast activation and cardiac fibrosis will likely yield powerful therapeutic approaches for the treatment of multiple diseases of the heart, including heart failure with preserved or reduced ejection fraction, acute coronary syndrome, and cardiovascular disease linked to type 2 diabetes. In this Review, we provide an overview of classical regulators of cardiac fibrosis and highlight emerging, next-generation epigenetic regulatory targets that have the potential to revolutionize treatment of the expanding cardiovascular disease patient population.

2,5-Dimethylcelecoxib attenuates cardiac fibrosis caused by cryoinjury-induced myocardial infarction by suppressing the fibroblast-to-myofibroblast transformation via inhibition of the TGF-β signaling pathway

We previously reported that 2,5-dimethylcelecoxib (DM-C), a derivative of celecoxib, lacks cyclooxygenase-2 inhibitory effects and suppresses cardiac remodeling by activating glycogen synthase kinase-3 (GSK-3). However, it remains unclear whether DM-C attenuates fibroblast-to-myofibroblast transformation (FMT), which plays a key role in cardiac fibrosis. Therefore, we evaluated the effect of DM-C on FMT using a cryoinjury-induced myocardial infarction (CMI) mouse model. We found that DM-C attenuated the deterioration of left ventricular ejection fraction after CMI by decreasing cardiac fibrosis. Analysis of the expression level of α-smooth muscle actin (α-SMA), a marker for myofibroblasts, indicated that DM-C decreased FMT at the cardiac injury site. To investigate the mechanism by which DM-C attenuated FMT, fibroblasts obtained from the heart were stimulated with TGF-β to induce FMT, and the effect of DM-C was analyzed. DM-C suppressed the expression of α-SMA and the phosphorylation levels of Smad 2/3 and GSK-3, indicating that DM-C suppressed α-SMA expression by inhibiting the transforming growth factor (TGF)-β signaling pathway via activation of GSK-3. DM-C decreased the expression of collagen, connective tissue growth factor (CTGF) and Snail, which are also known to accelerate cardiac fibrosis. These results suggested that DM-C attenuated cardiac fibrosis by suppressing FMT at the injured site after CMI by inhibiting the TGF-β signaling pathway via activation of GSK-3. Thus, DM-C has potential against cardiac disease as a novel anti-fibrotic agent.

Smad7 effects on TGF-β and ErbB2 restrain myofibroblast activation and protect from postinfarction heart failure

Repair of the infarcted heart requires TGF-β/Smad3 signaling in cardiac myofibroblasts. However, TGF-β-driven myofibroblast activation needs to be tightly regulated in order to prevent excessive fibrosis and adverse remodeling that may precipitate heart failure. We hypothesized that induction of the inhibitory Smad, Smad7, may restrain infarct myofibroblast activation, and we examined the molecular mechanisms of Smad7 actions. In a mouse model of nonreperfused infarction, Smad3 activation triggered Smad7 synthesis in α-SMA+ infarct myofibroblasts, but not in α-SMA-PDGFRα+ fibroblasts. Myofibroblast-specific Smad7 loss increased heart failure-related mortality, worsened dysfunction, and accentuated fibrosis in the infarct border zone and in the papillary muscles. Smad7 attenuated myofibroblast activation and reduced synthesis of structural and matricellular extracellular matrix proteins. Smad7 effects on TGF-β cascades involved deactivation of Smad2/3 and non-Smad pathways, without any effects on TGF-β receptor activity. Unbiased transcriptomic and proteomic analysis identified receptor tyrosine kinase signaling as a major target of Smad7. Smad7 interacted with ErbB2 in a TGF-β-independent manner and restrained ErbB1/ErbB2 activation, suppressing fibroblast expression of fibrogenic proteases, integrins, and CD44. Smad7 induction in myofibroblasts serves as an endogenous TGF-β-induced negative feedback mechanism that inhibits postinfarction fibrosis by restraining Smad-dependent and Smad-independent TGF-β responses, and by suppressing TGF-β-independent fibrogenic actions of ErbB2.

Regulation of collagen deposition in the trout heart during thermal acclimation

The passive mechanical properties of the vertebrate heart are controlled in part by the composition of the extracellular matrix (ECM). Changes in the ECM, caused by increased blood pressure, injury or disease can affect the capacity of the heart to fill with blood during diastole. In mammalian species, cardiac fibrosis caused by an increase in collagen in the ECM, leads to a loss of heart function and these changes in composition are considered to be permanent. Recent work has demonstrated that the cardiac ventricle of some fish species have the capacity to both increase and decrease collagen content in response to thermal acclimation. It is thought that these changes in collagen content help maintain ventricle function over seasonal changes in environmental temperatures. This current work reviews the cellular mechanisms responsible for regulating collagen deposition in the mammalian heart and proposes a cellular pathway by which a change in temperature can affect the collagen content of the fish ventricle through mechanotransduction. This work specifically focuses on the role of transforming growth factor β1, MAPK signaling pathways, and biomechanical stretch in regulating collagen content in the fish ventricle. It is hoped that this work increases the appreciation of the use of comparative models to gain insight into phenomenon with biomedical relevance.

Curcumin Ameliorates Cardiac Fibrosis by Regulating Macrophage-Fibroblast Crosstalk via IL18-P-SMAD2/3 Signaling Pathway Inhibition

Ethnopharmacological relevance: Curcumin is a bright yellow chemical produced by plants of the Curcuma longa species. Chemically, curcumin is a diarylheptanoid, belonging to the group of curcuminoids. The therapeutic potential of curcumin has been widely investigated, including its utilization in various of cardiovascular diseases. However, its effect in cardiac remodeling post myocardial infarction and underlying mechanism remains to be uncover.

Aim: To evaluate the therapeutic effect and underlying mechanism of curcumin on cardiac fibrosis after myocardial infarction via macrophage-fibroblast crosstalk.

Methods: Male C57BL/6 (C57) mice were subjected to left anterior descending coronary artery ligation to establish myocardial infarction and intragastrically fed vehicle or curcumin (50 mg/kg or 100 mg/kg) for 4 weeks. In parallel, neonatal rat cardiac fibroblasts were isolated and co-cultured with liposaccharide (LPS− or LPS+) curcumin-treated macrophages, followed by TGF-β stimulation for 24 h. Cardiac function was determined by 2-dimensional echocardiography, and cardiac fibrosis was measured by picrosirius red staining. Apoptosis of macrophages was investigated by flow cytometry; all pro-fibrotic protein expression (EDA-Fibronectin, Periostin, Vimentin, and α-SMA) as well as TGF-βR1 downstream signaling activation reflected by phosphorylated SMAD2/3 (p-SMAD2 and p-SMAD3) were demonstrated by western blotting.

Results: Curcumin significantly ameliorated the inflammation process subsequent to myocardial infarction, reflected by decreased expression of CD68+ and CD3+ cells, accompanied by dramatically improved cardiac function compared with the placebo group. In addition, cardiac fibrosis is inhibited by curcumin administration. Interestingly, no significant reduction in fibrotic gene expression was observed when isolated cardiac fibroblasts were directly treated with curcumin in vitro; however, pro-fibrotic protein expression was significantly attenuated in CF, which was co-cultured with LPS-stimulated macrophages under curcumin treatment compared with the placebo group. Mechanistically, we discovered that curcumin significantly downregulated pro-inflammatory cytokines in macrophages, which in turn inhibited IL18 expression in co-cultured cardiac fibroblasts using bulk RNA sequencing, and the TGF-β1-p-SMAD2/3 signaling network was also discovered as the eventual target downstream of IL18 in curcumin-mediated anti-fibrosis signaling.

Conclusion: Curcumin improves cardiac function and reduces cardiac fibrosis after myocardial infarction. This effect is mediated by the inhibition of macrophage-fibroblast crosstalk in the acute phase post-MI and retrained activation of IL18-TGFβ1-p-SMAD2/3 signaling in cardiac fibroblasts.

Transforming growth factor-β in myocardial disease

Transforming growth factor-β (TGFβ) isoforms are upregulated and activated in myocardial diseases and have an important role in cardiac repair and remodelling, regulating the phenotype and function of cardiomyocytes, fibroblasts, immune cells and vascular cells. Cardiac injury triggers the generation of bioactive TGFβ from latent stores, through mechanisms involving proteases, integrins and specialized extracellular matrix (ECM) proteins. Activated TGFβ signals through the SMAD intracellular effectors or through non-SMAD cascades. In the infarcted heart, the anti-inflammatory and fibroblast-activating actions of TGFβ have an important role in repair; however, excessive or prolonged TGFβ signalling accentuates adverse remodelling, contributing to cardiac dysfunction. Cardiac pressure overload also activates TGFβ cascades, which initially can have a protective role, promoting an ECM-preserving phenotype in fibroblasts and preventing the generation of injurious, pro-inflammatory ECM fragments. However, prolonged and overactive TGFβ signalling in pressure-overloaded cardiomyocytes and fibroblasts can promote cardiac fibrosis and dysfunction. In the atria, TGFβ-mediated fibrosis can contribute to the pathogenic substrate for atrial fibrillation. Overactive or dysregulated TGFβ responses have also been implicated in cardiac ageing and in the pathogenesis of diabetic, genetic and inflammatory cardiomyopathies. This Review summarizes the current evidence on the role of TGFβ signalling in myocardial diseases, focusing on cellular targets and molecular mechanisms, and discussing challenges and opportunities for therapeutic translation.

From dissection of fibrotic pathways to assessment of drug interactions to reduce cardiac fibrosis and heart failure

Cardiac fibrosis is characterized by extracellular matrix deposition in the cardiac interstitium, and this contributes to cardiac contractile dysfunction and progression of heart failure. The main players involved in this process are the cardiac fibroblasts, which, in the presence of pro-inflammatory/pro-fibrotic stimuli, undergo a complete transformation acquiring a more proliferative, a pro-inflammatory and a secretory phenotype. This review discusses the cellular effectors and molecular pathways implicated in the pathogenesis of cardiac fibrosis and suggests potential strategies to monitor the effects of specific drugs designed to slow down the progression of this disease by specifically targeting the fibroblasts.

TGFβ-Neurotrophin Interactions in Heart, Retina, and Brain

Ischemic insults to the heart and brain, i.e., myocardial and cerebral infarction, respectively, are amongst the leading causes of death worldwide. While there are therapeutic options to allow reperfusion of ischemic myocardial and brain tissue by reopening obstructed vessels, mitigating primary tissue damage, post-infarction inflammation and tissue remodeling can lead to secondary tissue damage. Similarly, ischemia in retinal tissue is the driving force in the progression of neovascular eye diseases such as diabetic retinopathy (DR) and age-related macular degeneration (AMD), which eventually lead to functional blindness, if left untreated. Intriguingly, the easily observable retinal blood vessels can be used as a window to the heart and brain to allow judgement of microvascular damages in diseases such as diabetes or hypertension. The complex neuronal and endocrine interactions between heart, retina and brain have also been appreciated in myocardial infarction, ischemic stroke, and retinal diseases. To describe the intimate relationship between the individual tissues, we use the terms heart-brain and brain-retina axis in this review and focus on the role of transforming growth factor β (TGFβ) and neurotrophins in regulation of these axes under physiologic and pathologic conditions. Moreover, we particularly discuss their roles in inflammation and repair following ischemic/neovascular insults. As there is evidence that TGFβ signaling has the potential to regulate expression of neurotrophins, it is tempting to speculate, and is discussed here, that cross-talk between TGFβ and neurotrophin signaling protects cells from harmful and/or damaging events in the heart, retina, and brain.

Fibrosis of the diabetic heart: Clinical significance, molecular mechanisms, and therapeutic opportunities

In patients with diabetes, myocardial fibrosis may contribute to the pathogenesis of heart failure and arrhythmogenesis, increasing ventricular stiffness and delaying conduction. Diabetic myocardial fibrosis involves effects of hyperglycemia, lipotoxicity and insulin resistance on cardiac fibroblasts, directly resulting in increased matrix secretion, and activation of paracrine signaling in cardiomyocytes, immune and vascular cells, that release fibroblast-activating mediators. Neurohumoral pathways, cytokines, growth factors, oxidative stress, advanced glycation end-products (AGEs), and matricellular proteins have been implicated in diabetic fibrosis; however, the molecular links between the metabolic perturbations and activation of a fibrogenic program remain poorly understood. Although existing therapies using glucose- and lipid-lowering agents and neurohumoral inhibition may act in part by attenuating myocardial collagen deposition, specific therapies targeting the fibrotic response are lacking. This review manuscript discusses the clinical significance, molecular mechanisms and cell biology of diabetic cardiac fibrosis and proposes therapeutic targets that may attenuate the fibrotic response, preventing heart failure progression.

Role of PI3K/Akt signaling pathway in cardiac fibrosis

Heart failure (HF) is considered as a severe health problem worldwide, while cardiac fibrosis is one of the main driving factors for the progress of HF. Cardiac fibrosis was characterized by changes in cardiomyocytes, cardiac fibroblasts, ratio of collagen (COL) I/III, and the excessive production and deposition of extracellular matrix (ECM), thus forming a scar tissue, which leads to pathological process of cardiac structural changes and systolic as well as diastolic dysfunction. Cardiac fibrosis is a common pathological change of many advanced cardiovascular diseases including ischemic heart disease, hypertension, and HF. Accumulated studies have proven that phosphoinositol-3 kinase (PI3K)/Akt signaling pathway is involved in regulating the occurrence, progression and pathological formation of cardiac fibrosis via regulating cell survival, apoptosis, growth, cardiac contractility and even the transcription of related genes through a series of molecules including mammalian target of rapamycin (mTOR), glycogen synthase kinase 3 (GSK-3), forkhead box proteins O1/3 (FoxO1/3), and nitric oxide synthase (NOS). Thus, the review focuses on the role of PI3K/Akt signaling pathway in the cardiac fibrosis. The information reviewed here should be significant in understanding the role of PI3K/Akt in cardiac fibrosis and contribute to the design of further studies related to PI3K/Akt and the cardiac fibrotic response, as well as sought to shed light on a potential treatment for cardiac fibrosis.

Ufbp1, a Key Player of Ufm1 Conjugation System, Protects Against Ketosis-Induced Liver Injury via Suppressing Smad3 Activation

The dairy cattle suffer from severe liver dysfunction during the pathogenesis of ketosis. The Ufm1 conjugation system is crucial for liver development and homeostasis. Ufm1 binding protein (Ufbp1) is a putative Ufm1 target and an integral component, but its role in ketosis-induced liver injury is unclear so far. The purpose of this study is to explore the key role of Ufbp1 in liver fibrosis caused by ketosis in vivo and in vitro. Liver tissues were collected from ketotic cows and Ufbp1 conditional knockout (CKO) mice in vivo. However, Ufbp1^–/– mouse embryonic fibroblast cells and Hela cells were used for in vitro validation. Subsequently, various assays were performed to reveal the underlying molecular mechanisms of the Ufbp1 protective effect. In this study, hepatic fibrosis, endoplasmic reticulum (ER) stress, and apoptosis were reported in the liver of ketotic cows, fibrotic markers (alpha-smooth muscle actin, Collagen1) and ER stress markers (glucose-regulated protein 78, CEBP homologous protein) were upregulated remarkably, and the apoptosis-related genes (Bcl2, Bax) were in line with expectations. Interestingly, Ufbp1 expression was almost disappeared, and Smad2/Smad3 protein was largely phosphorylated in the liver of ketotic cows, but Ufbp1 deletion caused Smad3 phosphorylation apparently, rather than Smad2, and elevated ER stress was observed in the CKO mice model. At the cellular level, Ufbp1 deficiency led to serious fibrotic and ER stress response, Smad3 was activated by phosphorylation significantly and then was translocated into the nucleus, whereas p-Smad2 was largely unaffected in embryonic fibroblast cells. Ufbp1 overexpression obviously suppressed Smad3 phosphorylation in Hela cells. Ufbp1 was found to be in full combination with Smad3 using endogenous immunoprecipitation. Taken together, our findings suggest that downregulation or ablation of Ufbp1 leads to Smad3 activation, elevated ER stress, and hepatocyte apoptosis, which in turn causes liver fibrosis. Ufbp1 plays a protective role in ketosis-induced liver injury.