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

An Allysine-Conjugatable Probe for Fluorogenically Imaging Fibrosis

Allysine, a pivotal biomarker in fibrogenesis, has prompted the development of various radioactive imaging probes. However, fluorogenic probes targeting allysine remain largely unexplored. Herein, by leveraging the equilibrium between the nonfluorescent spirocyclic and the fluorescent zwitterionic forms of rhodamine-cyanine hybrid fluorophores, we systematically fine-tuned the environmental sensitivity of this equilibrium toward the development of fluorogenic probes for fibrosis. The trick lies in modulating the nucleophilicity of the ortho-carboxyl group, which is terminated with a hydrazide group for allysine conjugation. Probe B2 was developed with this strategy, which featured an N-sulfonyl amide group and exhibited superior fibrosis-to-control imaging contrast. Initially presenting as nonfluorescent spirocyclic aggregates in aqueous solutions, B2 displayed a notable fluorogenic response upon conjugation with protein allysine through its hydrazide group, inducing deaggregation and switching to the fluorescent zwitterionic form. Probe B2 outperformed the traditional Masson stain in imaging contrast, achieving an about 260-2600-fold ratio for fibrosis-to-control detection depending on fibrosis severity. Furthermore, it demonstrated efficacy in evaluating antifibrosis drugs. Our results emphasize the potential of this fluorogenic probe as an alternative to conventional fibrosis detection methods. It emerges as a valuable tool for antifibrosis drug evaluation.

Role of NF-κB in cardiac changes of obstructive sleep apnoea rabbits treated by mandibular advancement device

BACKGROUND

Obstructive sleep apnoea (OSA) is an independent risk factor for cardiovascular diseases. We aimed to investigate the role of nuclear factor-kappa B (NF-κB) in the changes of cardiac structures in OSA rabbits treated by mandibular advancement device (MAD).

METHODS

Eighteen male New Zealand white rabbits aged 6 months were randomly divided into three groups: control group, group OSA and group MAD. Hyaluronate gel was injected into the soft palate of the rabbits in group OSA and group MAD to induce OSA. The cone beam computer tomography (CBCT) of the upper airway and polysomnography (PSG) was performed to ensure successful modelling. CBCT and PSG were applied again to detect the effects of MAD treatment. All animals were induced to sleep in a supine position for 4-6 h a day for 8 weeks. Then the levels of NF-κB, Interleukin 6 (IL-6), Interleukin 10 (IL-10) and the proportion of myocardial fibrosis (MF) were detected.

RESULTS

The higher activation of NF-κB, IL-6 and IL-10 were found in the OSA group than in the control group, leading to the increase of collagen fibres compared with the control group. Furthermore, the apnoea-hypopnea index (AHI) was positively correlated with the above factors. There were no significant differences between group MAD and the control group.

CONCLUSION

The NF-κB pathway was activated in the myocardium of OSA rabbits, which accelerated the development of MF. Early application of MAD could reduce the activation of NF-κB in the myocardium and prevent the development of MF.

Polysaccharides play an anti-fibrotic role by regulating intestinal flora: A review of research progress

Fibrosis is a common pathological process affecting multiple organs. It refers to an increase in fibrous connective tissue and a decrease in parenchymal cells in damaged tissues or organs. This may lead to structural damage and functional decline or even organ failure. The incidence of fibrosis is increasing worldwide, and the need for safe and effective therapeutic drugs and treatments is pivotal. The intestinal tract has a complex network of exchanging information with various tissues in the body. It contains a sizeable microbial community of which the homeostasis and metabolites are closely related to fibrosis. Polysaccharides are a class of biomolecules present in natural products; they have potential value as anti-fibrotic prebiotics. Recently, polysaccharides have been found to improve fibrosis in different organs by decreasing inflammation and modulating the immune function and intestinal microbiota. In this paper, we reviewed the progress made in research concerning polysaccharides and organ fibrosis in relation to the intestinal microbiota from the pathogenesis of fibrosis to the relationship between the intestinal flora and fibrosis. Furthermore, we provide ideas and references for future polysaccharide-drug discovery and strategies for the treatment of fibrosis.

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.

CXCL4:NLRP3-mediated pyroptosis product that regulates cardiac fibrosis

Severe myocarditis is often accompanied by cardiac fibrosis, but the underlying mechanism has not been fully elucidated. NOD-like receptor protein 3 (NLRP3) inflammation is involved in the development of myocarditis and is closely related to the form of cell death. Inhibiting pyroptosis mediated by NLRP3 inflammasome can reduce cardiac fibrosis, although its exact mechanism remains unknown. In this study, we induced Viral myocarditis (VMC) via infection of CVB3 to explore the relationship between pyroptosis and fibrosis. Our results showed that intraperitoneal injection of an NLRP3 inhibitor MCC950 or use of NLRP3-/- mice inhibited cardiac pyroptosis mediated by NLRP3 inflammasome in VMC. CXCL4 is a chemokine that has been reported to have pro-inflammatory and pro-fibrotic functions. In VMC, we further found that pyroptosis of Mouse myocardial fibroblasts (MCF) promoted the secretion of CXCL4 by activating Wnt/β-Catenin signaling. Subsequently, the transcriptome sequencing data showed that CXCL4 could promote cardiac fibrosis by activating PI3K/AKT pathway. In summary, infection of CVB3 induced host oxidative stress to further activate the NLRP3 inflammasome and ultimately lead to heart pyroptosis, in which MCF secreted CXCL4 by activating Wnt/β-Catenin signaling and CXCL4 participated in cardiac fibrosis by activating PI3K/AKT pathway. Therefore, our findings revealed the role of CXCL4 in VMC and unveiled its underlying mechanism. CXCL4 appears to be a potential target for the treatment of VMC.

Inducible Fgf13 ablation alleviates cardiac fibrosis via regulation of microtubule stability

Fibroblast growth factor (FGF) isoform 13, a distinct type of FGF, boasts significant potential for therapeutic intervention in cardiovascular dysfunctions. However, its impact on regulating fibrosis remains unexplored. This study aims to elucidate the role and mechanism of FGF13 on cardiac fibrosis. Here, we show that following transverse aortic constriction (TAC) surgery, interstitial fibrosis and collagen content increase in mice, along with reduced ejection fraction and fractional shortening, augmented heart mass. However, following Fgf13 deletion, interstitial fibrosis is decreased, ejection fraction and fractional shortening are increased, and heart mass is decreased, compared with those in the TAC group. Mechanistically, incubation of cardiac fibroblasts with transforming growth factor β (TGFβ) increases the expressions of types I and III collagen proteins, as well as α-smooth muscle actin (α-SMA) proteins, and enhances fibroblast proliferation and migration. In the absence of Fgf13, the expressions of these proteins are decreased, and fibroblast proliferation and migration are suppressed, compared with those in the TGFβ-stimulated group. Overexpression of FGF13, but not FGF13 mutants defective in microtubule binding and stabilization, rescues the decrease in collagen and α-SMA protein and weakens the proliferation and migration function of the Fgf13 knockdown group. Furthermore, Fgf13 knockdown decreases ROCK protein expression via microtubule disruption. Collectively, cardiac Fgf13 knockdown protects the heart from fibrosis in response to haemodynamic stress by modulating microtubule stabilization and ROCK signaling pathway.

Mast cells: a novel therapeutic avenue for cardiovascular diseases?

Mast cells are tissue-resident immune cells strategically located in different compartments of the normal human heart (the myocardium, pericardium, aortic valve, and close to nerves) as well as in atherosclerotic plaques. Cardiac mast cells produce a broad spectrum of vasoactive and proinflammatory mediators, which have potential roles in inflammation, angiogenesis, lymphangiogenesis, tissue remodelling, and fibrosis. Mast cells release preformed mediators (e.g. histamine, tryptase, and chymase) and de novo synthesized mediators (e.g. cysteinyl leukotriene C4 and prostaglandin D2), as well as cytokines and chemokines, which can activate different resident immune cells (e.g. macrophages) and structural cells (e.g. fibroblasts and endothelial cells) in the human heart and aorta. The transcriptional profiles of various mast cell populations highlight their potential heterogeneity and distinct gene and proteome expression. Mast cell plasticity and heterogeneity enable these cells the potential for performing different, even opposite, functions in response to changing tissue contexts. Human cardiac mast cells display significant differences compared with mast cells isolated from other organs. These characteristics make cardiac mast cells intriguing, given their dichotomous potential roles of inducing or protecting against cardiovascular diseases. Identification of cardiac mast cell subpopulations represents a prerequisite for understanding their potential multifaceted roles in health and disease. Several new drugs specifically targeting human mast cell activation are under development or in clinical trials. Mast cells and/or their subpopulations can potentially represent novel therapeutic targets for cardiovascular disorders.

Circular RNAs: a small piece in the heart failure puzzle

Cardiovascular disease, specifically heart failure (HF), remains a significant concern in the realm of healthcare, necessitating the development of new treatments and biomarkers. The RNA family consists of various subgroups, including microRNAs, PIWI-interacting RNAs (piRAN) and long non-coding RNAs, which have shown potential in advancing personalized healthcare for HF patients. Recent research suggests that circular RNAs, a lesser-known subgroup of RNAs, may offer a novel set of targets and biomarkers for HF. This review will discuss the biogenesis of circular RNAs, their unique characteristics relevant to HF, their role in heart function, and their potential use as biomarkers in the bloodstream. Furthermore, future research directions in this field will be outlined. The stability of exosomal circRNAs makes them suitable as biomarkers, pathogenic regulators, and potential treatments for cardiovascular diseases such as atherosclerosis, acute coronary syndrome, ischemia/reperfusion injury, HF, and peripheral artery disease. Herein, we summarized the role of circular RNAs and their exosomal forms in HF diseases.

The effect of macrophages and their exosomes in ischemic heart disease

Ischemic heart disease (IHD) is a leading cause of disability and death worldwide, with immune regulation playing a crucial role in its pathogenesis. Various immune cells are involved, and as one of the key immune cells residing in the heart, macrophages play an indispensable role in the inflammatory and reparative processes during cardiac ischemia. Exosomes, extracellular vesicles containing lipids, nucleic acids, proteins, and other bioactive molecules, have emerged as important mediators in the regulatory functions of macrophages and hold promise as a novel therapeutic target for IHD. This review summarizes the regulatory mechanisms of different subsets of macrophages and their secreted exosomes during cardiac ischemia over the past five years. It also discusses the current status of clinical research utilizing macrophages and their exosomes, as well as strategies to enhance their therapeutic efficacy through biotechnology. The aim is to provide valuable insights for the treatment of IHD.

The Application of Berberine in Fibrosis and the Related Diseases

The formation of fibrotic tissue, characterized by the excessive accumulation of extracellular matrix (ECM) components such as collagen and fibronectin, is a normal and crucial stage of tissue repair in all organs. The over-synthesis, deposition, and remodeling of ECM components lead to organ dysfunction, posing a significant medical burden. Berberine, an isoquinoline alkaloid, is commonly used in the treatment of gastrointestinal diseases. With the deepening of scientific research, it has been gradually discovered that berberine also plays an important role in fibrotic diseases. In this review, we systematically introduce the effective role of berberine in fibrosis-related diseases. Specifically, this paper aims to provide a comprehensive review of the therapeutic role of berberine in treating fibrosis in organs such as the heart, liver, lungs, and kidneys. By summarizing its various pathways and mechanisms of action, including the inhibition of the transforming growth factor-[Formula: see text]/Smad signaling pathway, PI3K/Akt signaling pathway, MAPK signaling pathway, RhoA/ROCK signaling, and mTOR/p70S6K signaling pathway, as well as its activation of the Nrf2-ARE signaling pathway, AMPK signaling pathway, phosphorylated Smad 2/3 and Smad 7, and other signaling pathways, this review offers additional evidence to support the treatment of fibrotic diseases.

Redox homeostasis in cardiac fibrosis: Focus on metal ion metabolism

Cardiac fibrosis is a major public health problem worldwide, with high morbidity and mortality, affecting almost all patients with heart disease worldwide. It is characterized by fibroblast activation, abnormal proliferation, excessive deposition, and abnormal distribution of extracellular matrix (ECM) proteins. The maladaptive process of cardiac fibrosis is complex and often involves multiple mechanisms. With the increasing research on cardiac fibrosis, redox has been recognized as an important part of cardiac remodeling, and an imbalance in redox homeostasis can adversely affect the function and structure of the heart. The metabolism of metal ions is essential for life, and abnormal metabolism of metal ions in cells can impair a variety of biochemical processes, especially redox. However, current research on metal ion metabolism is still very limited. This review comprehensively examines the effects of metal ion (iron, copper, calcium, and zinc) metabolism-mediated redox homeostasis on cardiac fibrosis, outlines possible therapeutic interventions, and addresses ongoing challenges in this rapidly evolving field.

Potential therapeutic targets of fibrosis in inflammatory rheumatic diseases

Fibrosis is commonly associated with chronic rheumatic diseases, and causes substantial morbidity and mortality. Treatment of fibrosis is extremely challenging but is badly needed, as approved antifibrotic therapies fibrosis do not halt its progression, which will be discussed with a focus on pulmonary fibrosis. Findings from recent studies indicate several therapeutic targets for treating fibrosis. Interleukin-11 is emerging as a fibrogenic cytokine whose activity can be blocked with neutralizing monoclonal antibodies. Fibroblast activation protein (FAP) is highly expressed by activated fibroblasts in inflammatory and fibrotic tissues. Targeting FAP with different modalities has been extensively explored as adjunct treatment for cancer, which can also apply to treating fibrosis in rheumatic diseases.

Large animal models of pressure overload-induced cardiac left ventricular hypertrophy to study remodelling of the human heart with aortic stenosis

Pathologic cardiac hypertrophy is a common consequence of many cardiovascular diseases, including aortic stenosis (AS). AS is known to increase the pressure load of the left ventricle, causing a compensative response of the cardiac muscle, which progressively will lead to dilation and heart failure. At a cellular level, this corresponds to a considerable increase in the size of cardiomyocytes, known as cardiomyocyte hypertrophy, while their proliferation capacity is attenuated upon the first developmental stages. Cardiomyocytes, in order to cope with the increased workload (overload), suffer alterations in their morphology, nuclear content, energy metabolism, intracellular homeostatic mechanisms, contractile activity, and cell death mechanisms. Moreover, modifications in the cardiomyocyte niche, involving inflammation, immune infiltration, fibrosis, and angiogenesis, contribute to the subsequent events of a pathologic hypertrophic response. Considering the emerging need for a better understanding of the condition and treatment improvement, as the only available treatment option of AS consists of surgical interventions at a late stage of the disease, when the cardiac muscle state is irreversible, large animal models have been developed to mimic the human condition, to the greatest extend. Smaller animal models lack physiological, cellular and molecular mechanisms that sufficiently resemblance humans and in vitro techniques yet fail to provide adequate complexity. Animals, such as the ferret (Mustello purtorius furo), lapine (rabbit, Oryctolagus cunigulus), feline (cat, Felis catus), canine (dog, Canis lupus familiaris), ovine (sheep, Ovis aries), and porcine (pig, Sus scrofa), have contributed to research by elucidating implicated cellular and molecular mechanisms of the condition. Essential discoveries of each model are reported and discussed briefly in this review. Results of large animal experimentation could further be interpreted aiming at prevention of the disease progress or, alternatively, at regression of the implicated pathologic mechanisms to a physiologic state. This review summarizes the important aspects of the pathophysiology of LV hypertrophy and the applied surgical large animal models that currently better mimic the condition.

Targeting Interactions between Fibroblasts and Macrophages to Treat Cardiac Fibrosis

Excessive extracellular matrix (ECM) deposition is a defining feature of cardiac fibrosis. Most notably, it is characterized by a significant change in the concentration and volume fraction of collagen I, a disproportionate deposition of collagen subtypes, and a disturbed ECM network arrangement, which directly affect the systolic and diastolic functions of the heart. Immune cells that reside within or infiltrate the myocardium, including macrophages, play important roles in fibroblast activation and consequent ECM remodeling. Through both direct and indirect connections to fibroblasts, monocyte-derived macrophages and resident cardiac macrophages play complex, bidirectional, regulatory roles in cardiac fibrosis. In this review, we discuss emerging interactions between fibroblasts and macrophages in physiology and pathologic conditions, providing insights for future research aimed at targeting macrophages to combat cardiac fibrosis.

Alpha 7 Nicotinic Acetylcholine Receptor Agonist PHA 568487 Reduces Acute Inflammation but Does Not Affect Cardiac Function or Myocardial Infarct Size in the Permanent Occlusion Model

Stimulation of the alpha 7 nicotinic acetylcholine receptor (α7nAChR) has shown beneficial effects in several acute inflammatory disease models. This study aims to examine whether treatment with the selective α7nAChR agonist PHA 568487 can dampen inflammation and thereby improve cardiac function after myocardial infarction in mice. The possible anti-inflammatory properties of α7nAChR agonist PHA 568487 were tested in vivo using the air pouch model and in a permanent occlusion model of acute myocardial infarction in mice. Hematologic parameters and cytokine levels were determined. Infarct size and cardiac function were assessed via echocardiography 24 h and one week after the infarction. Treatment with α7nAChR agonist PHA 568487 decreased 12 (CCL27, CXCL5, IL6, CXCL10, CXCL11, CXCL1, CCL2, MIP1a, MIP2, CXCL16, CXCL12 and CCL25) out of 33 cytokines in the air pouch model of acute inflammation. However, α7nAChR agonist PHA 568487 did not alter infarct size, ejection fraction, cardiac output or stroke volume at 24 h or at 7 days after the myocardial infarction compared with control mice. In conclusion, despite promising immunomodulatory effects in the acute inflammatory air pouch model, α7nAChR agonist PHA 568487 did not affect infarct size or cardiac function after a permanent occlusion model of acute myocardial infarction in mice. Consequently, this study does not strengthen the hypothesis that stimulation of the α7nAChR is a future treatment strategy for acute myocardial infarction when reperfusion is lacking. However, whether other agonists of the α7nAChR can have different effects remains to be investigated.

The impact of high-altitude and cold environment on brain and heart damage in rats with hemorrhagic shock

BACKGROUND

Hemorrhagic shock (HS) causes severe organ damage, worsened by high-altitude conditions with lower oxygen and temperatures. Existing research lacks specific insights on brain and heart damage under these conditions. This study hypothesizes that high-altitude and cold (HAC) environments exacerbate HS-induced damage in the brain and heart, aiming to improve treatment strategies.

MATERIALS AND METHODS

Twenty-four male Sprague-Dawley (SD) rats (200-250 g of weight) were randomly assigned into sham, HS + normal, HS + HAC (4,000 m), and HS + HAC (6,000 m). The HS model was established in SD rats (35% loss of total blood volume), and histopathological injuries of the brain and heart were detected using hematoxylin and eosin staining, Sirius red staining, and immunohistochemistry. Apoptosis of the brain and heart tissues was detected by terminal transferase-mediated dUTP nick end labeling (TUNEL) immunofluorescence staining. To determine the levels of tumor necrosis factor-α (TNF-α), interferon-gamma (IFN-γ), monocyte chemoattractant protein-1 (Mcp-1), BCL2-associated X (BAX), and myeloid cell leukemia-1 (Mcl-1) protein, western blotting assay was used.

RESULTS

The HAC environment induced pathological damage to the brain and heart and aggravated the degree of cardiac fibrosis in HS rats. However, it did not cause apoptosis of the brain and heart. In addition, it upregulated TNF-α, IFN-γ, Mcp-1, and BAX protein levels, but downregulated Mcl-1 protein levels (P < 0.05).

CONCLUSIONS

The HAC environment aggravated the degree of brain and heart damage in HS rats, which may be related to neuron nucleus pyknosis, myocardial fibrosis, and inflammatory and apoptosis activation.

The role of fibrosis in cardiomyopathies: An opportunity to develop novel biomarkers of disease activity

Cardiomyopathies encompass a spectrum of heart disorders with diverse causes and presentations. Fibrosis stands out as a shared hallmark among various cardiomyopathies, reflecting a common thread in their pathogenesis. This prevalent fibrotic response is intricately linked to the consequences of dysregulated extracellular matrix (ECM) remodeling, emphasizing its significance in the development and progression the disease. This review explores the ECM involvement in various cardiomyopathies and its impact on myocardial stiffness and fibrosis. Additionally, we discuss the potential of ECM fragments as early diagnosis, prognosis, and risk stratification. Biomarkers deriving from turnover of collagens and other ECM proteins hold promise in clinical applications. We outline current clinical management, future directions, and the potential for personalized ECM-targeted therapies with specific focus on microRNAs. In summary, this review examines the role of the fibrosis in cardiomyopathies, highlighting the potential of ECM-derived biomarkers in improving disease management with implications for precision medicine.

Indoxyl sulphate-initiated activation of cardiac fibroblasts is modulated by aryl hydrocarbon receptor and nuclear factor-erythroid-2-related factor 2

In the last decade, extensive attention has been paid to the uremic toxin indoxyl sulphate (IS) as an inducer of cardiac fibroblast (cFib) activation and cardiac fibrosis in chronic kidney disease. At cellular level, IS engages aryl hydrocarbon receptor (AhR) and regulates many biological functions. We analysed how AhR inhibition by CH-223191 (CH) and overexpression of non-functional (dominant negative, DN) nuclear factor-erythroid-2-related factor 2 (NRF2), a transcription factor recruited by AhR, modulate the response of neonatal mouse (nm) cFib to IS. We also evaluated nm-cardiomyocytes after incubation with the conditioned medium (CM) of IS±CH-treated nm-cFib. IS induced activation, collagen synthesis, TLR4 and-downstream-MCP-1, and the genes encoding angiotensinogen, angiotensin-converting enzyme, angiotensin type 1 receptor (AT1r) and neprilysin (Nepr) in nm-cFib. CH antagonized IS-initiated nm-cFib activation, but did not affect or even magnified the other features. IS promoted NRF2 nuclear translocation and expression the NRF2 target Nqo1. Both pre-incubation with CH and transfection of DN-NRF2 resulted in loss of NRF2 nuclear localization. Moreover, DN-NRF2 overexpression led to greater TLR4 and MCP-1 levels following exposure to IS. The CM of IS-primed nm-cFib and to a larger extent the CM of IS+CH-treated nm-cFib upregulated AT1r, Nepr and TNFα and myostatin genes in nm-cardiomyocytes. Hence, IS triggers pro-inflammatory activation of nm-cFib partly via AhR, and AhR-NRF2 counteract it. Strategies other than AhR inhibition are needed to target IS detrimental actions on cardiac cells.

Targeting S100A9 Prevents β-Adrenergic Activation-Induced Cardiac Injury

Altered cardiac innate immunity is highly associated with the progression of cardiac disease states and heart failure. S100A8/A9 is an important component of damage-associated molecular patterns (DAMPs) that is critically involved in the pathogenesis of heart failure, thus considered a promising target for pharmacological intervention. In the current study, initially, we validated the role of S100A8/A9 in contributing to cardiac injury and heart failure via the overactivation of the β-adrenergic pathway and tested the potential use of paquinimod as a pharmacological intervention of S100A8/A9 activation in preventing cardiac dysfunction, collagen deposition, inflammation, and immune cell infiltration in β-adrenergic overactivation-mediated heart failure. This finding was further confirmed by the cardiomyocyte-specific silencing of S100A9 via the use of the adeno-associated virus (AAV) 9-mediated short hairpin RNA (shRNA) gene silencing system. Most importantly, in the assessment of the underlying cellular mechanism by which activated S100A8/A9 cause aggravated progression of cardiac fibrosis and heart failure, we discovered that the activated S100A8/A9 can promote fibroblast-macrophage interaction, independent of inflammation, which is likely a key mechanism leading to the enhanced collagen production. Our results revealed that targeting S100A9 provides dual beneficial effects, which is not only a strategy to counteract cardiac inflammation but also preclude cardiac fibroblast-macrophage interactions. The findings of this study also indicate that targeting S100A9 could be a promising strategy for addressing cardiac fibrosis, potentially leading to future drug development.

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

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

Investigating Oxidative Stress Associated with Myocardial Fibrosis by High-Fidelity Visualization and Accurate Evaluation of Mitochondrial GSH Levels

Myocardial fibrosis is frequently accompanied by elevated levels of oxidative stress. Mitochondrial glutathione (mGSH), an essential biomolecule for maintaining redox homeostasis in mitochondria, could serve as an effective indicator for investigating the oxidative stress associated with myocardial fibrosis. In this study, a ratiometric fluorescent probe named Mito-NS6, capable of being anchored in mitochondria and reversibly responding to GSH with an appropriate dissociation equilibrium constant, was rationally designed and utilized to visualize and evaluate the changes of mGSH levels caused by oxidative stress in myocardial fibrosis. Benefiting from the good performance of Mito-NS6, we successfully achieved the quantification of mGSH in cardiac fibroblasts using a confocal laser-scanning microscope, revealing that salvianolic acid B (SalB) can act as an effective drug to alleviate myocardial fibrosis through depressing oxidative stress. Moreover, we employed ratio fluorescence imaging to track the fluctuation in GSH levels within a mice model of myocardial fibrosis induced by isoproterenol and found that myocardial fibrosis caused a higher oxidative stress level in myocardial tissue as well as heart organs. These results provide a novel point of view for the diagnosis and treatment of myocardial fibrosis.

Analysis of immunoinfiltration and EndoMT based on TGF-β signaling pathway-related genes in acute myocardial infarction

Acute myocardial infarction (AMI), a critical manifestation of coronary heart disease, presents a complex and not entirely understood etiology. This study investigates the potential role of immune infiltration and endothelial-mesenchymal transition (EndoMT) in AMI pathogenesis. We conducted an analysis of the GSE24519 and MSigDB datasets to identify differentially expressed genes associated with the TGF-β signaling pathway (DE-TSRGs) and carried out a functional enrichment analysis. Additionally, we evaluated immune infiltration in AMI and its possible link to myocardial fibrosis. Key genes were identified using machine learning and LASSO logistic regression. The expression of MEOX1 in the ventricular muscles and endothelial cells of Sprague-Dawley rats was assessed through RT-qPCR, immunohistochemical and immunofluorescence assays, and the effect of MEOX1 overexpression on EndoMT was investigated. Our study identified five DE-TSRGs, among which MEOX1, SMURF1, and SPTBN1 exhibited the most significant associations with AMI. Notably, we detected substantial immune infiltration in AMI specimens, with a marked increase in neutrophils and macrophages. MEOX1 demonstrated consistent expression patterns in rat ventricular muscle tissue and endothelial cells, and its overexpression induced EndoMT. Our findings suggest that the TGF-β signaling pathway may contribute to AMI progression by activating the immune response. MEOX1, linked to the TGF-β signaling pathway, appears to facilitate myocardial fibrosis via EndoMT following AMI. These novel insights into the mechanisms of AMI pathogenesis could offer promising therapeutic targets for intervention.

MicroRNAs regulating signaling pathways in cardiac fibrosis: potential role of the exercise training

Cardiovascular and metabolic diseases such as hypertension, type 2 diabetes, and obesity develop long-term fibrotic processes in the heart, promoting pathological cardiac remodeling, including after myocardial infarction, reparative fibrotic processes also occur. These processes are regulated by many intracellular signaling pathways that have not yet been completely elucidated, including those associated with microRNA (miRNA) expression. miRNAs are small RNA transcripts (18-25 nucleotides in length) that act as posttranscriptionally regulators of gene expression, inhibiting or degrading one or more target messenger RNAs (mRNAs), and proven to be involved in many biological processes such as cell cycle, differentiation, proliferation, migration, and apoptosis, directly affecting the pathophysiology of several diseases, including cardiac fibrosis. Exercise training can modulate the expression of miRNAs and it is known to be beneficial in various cardiovascular diseases, attenuating cardiac fibrosis processes. However, the signaling pathways modulated by the exercise associated with miRNAs in cardiac fibrosis were not fully understood. Thus, this review aims to analyze the expression of miRNAs that modulate signaling pathways in cardiac fibrosis processes that can be regulated by exercise training.

Fibroblasts and platelets: a face-to-face dialogue at the heart of cardiac fibrosis

Myocardial fibrosis is a feature found in most cardiac diseases and a key element contributing to heart failure and its progression. It has therefore become a subject of particular interest in cardiac research. Mechanisms leading to pathological cardiac remodeling and heart failure are diverse, including effects on cardiac fibroblasts, the main players in cardiac extracellular matrix synthesis, but also on cardiomyocytes, immune cells, endothelial cells, and more recently, platelets. Although transforming growth factor-β (TGF-β) is a primary regulator of fibrosis development, the cellular and molecular mechanisms that trigger its activation after cardiac injury remain poorly understood. Different types of anti-TGF-β drugs have been tested for the treatment of cardiac fibrosis and have been associated with side effects. Therefore, a better understanding of these mechanisms is of great clinical relevance and could allow us to identify new therapeutic targets. Interestingly, it has been shown that platelets infiltrate the myocardium at an early stage after cardiac injury, producing large amounts of cytokines and growth factors. These molecules can directly or indirectly regulate cells involved in the fibrotic response, including cardiac fibroblasts and immune cells. In particular, platelets are known to be a major source of TGF-β1. In this review, we have provided an overview of the classical cellular effectors involved in the pathogenesis of cardiac fibrosis, focusing on the emergent role of platelets, while discussing opportunities for novel therapeutic interventions.

Potential Effects of Orally Ingesting Polyethylene Terephthalate Microplastics on the Mouse Heart

Polyethylene terephthalate microplastics (PET MPs) are widespread in natural environment, and can enter organisms and accumulate in the body, but its toxicity has not been well studied. Therefore, in order to investigate the toxic effects of PET microplastics on mammals, this study investigated the toxic effects of PET MPs on ICR mice and H9C2 cells by different treatment groups. The results indicated the cardiac tissue of mice in the PET-H (50 µg/mL) group showed significant capillary congestion, myocardial fiber breakage, and even significant fibrosis compared to the PET-C (control) group (P < 0.01). Results of the TUNEL assay demonstrated significant apoptosis in myocardial tissue in the PET-H and PET-M (5 µg/mL) groups (P < 0.01). Meanwhile, Western blotting showed increased expression of the apoptosis-related protein Bax and decreased expression of PARP, caspase-3, and Bcl-2 proteins in both myocardial tissues and H9C2 cells. In addition, flow cytometry confirmed that PET MPs decreased the mitochondrial membrane potential and apoptosis in H9C2 cells; however, this trend was reversed by N-acetylcysteamine application. Moreover, PET MP treatment induced the accumulation of reactive oxygen species (ROS) in H9C2 cells, while the MDA level in the myocardial tissue was elevated, and the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) were decreased (P < 0.01), indicating a change in the redox environment. In conclusion, PET MPs promoted cardiomyocyte apoptosis by inducing oxidative stress and activating mitochondria-mediated apoptotic processes, ultimately leading to myocardial fibrosis. This study provides ideas for the prevention of PET MP toxicity and promotes thinking about enhancing plastic pollution control.

Heart-on-a-chip systems: disease modeling and drug screening applications

Cardiovascular disease (CVD) is the leading cause of death worldwide, casting a substantial economic footprint and burdening the global healthcare system. Historically, pre-clinical CVD modeling and therapeutic screening have been performed using animal models. Unfortunately, animal models oftentimes fail to adequately mimic human physiology, leading to a poor translation of therapeutics from pre-clinical trials to consumers. Even those that make it to market can be removed due to unforeseen side effects. As such, there exists a clinical, technological, and economical need for systems that faithfully capture human (patho)physiology for modeling CVD, assessing cardiotoxicity, and evaluating drug efficacy. Heart-on-a-chip (HoC) systems are a part of the broader organ-on-a-chip paradigm that leverages microfluidics, tissue engineering, microfabrication, electronics, and gene editing to create human-relevant models for studying disease, drug-induced side effects, and therapeutic efficacy. These compact systems can be capable of real-time measurements and on-demand characterization of tissue behavior and could revolutionize the drug development process. In this review, we highlight the key components that comprise a HoC system followed by a review of contemporary reports of their use in disease modeling, drug toxicity and efficacy assessment, and as part of multi-organ-on-a-chip platforms. We also discuss future perspectives and challenges facing the field, including a discussion on the role that standardization is expected to play in accelerating the widespread adoption of these platforms.

Pharmacological inhibition of ICOS attenuates the protective effect of exercise on cardiac fibrosis induced by isoproterenol

AIMS

To investigate the cardioprotective mechanism of exercise or exercise combined with inducible costimulatory molecules (ICOS) monoclonal antibody (mAb) therapy against isoproterenol (ISO)-induced cardiac remodeling.

MAIN METHODS

Totally 24 male C57BL/6J mice were randomly divided into four groups: the control group (normal saline treatment), ISO group (subcutaneous injection of isoproterenol, 10 mg/kg/day, once daily for 5 consecutive days), the exercise with subcutaneous ISO injection group (EPI), and the exercise with injected with ISO and ICOS mAb group (EPII). The mice in EPI and EPII group were trained on a small animal treadmill for 4 weeks (13 m/min, 0% grade, 60min/day).

KEY FINDINGS

Exercise significantly attenuated CD45+, Mac-2 inflammatory cell infiltration, cardiac fibrosis and inhibited the RIPK1/RIPK3/MLKL/CaMKII and cardiomyocyte pyroptosis pathways to counter ISO-induced severe cardiac injury. The administration of the ICOS mAb may inhibit the cardioprotection of exercise against ISO-induced heart damage. Compared to those in EPI, our data showed that the increasing levels of myocardial fibrosis, the leukocyte infiltration of cardiac tissue and proteins expression of cardiac myocyte necrosis and pyroptosis signaling pathways in the EPII group.

SIGNIFICANCE

Our results demonstrated that exercise decreased leukocyte infiltration in heart, inhibited the cardiomyocyte pyroptosis and necroptosis signaling pathways, and attenuated inflammatory responses to alleviate ISO-induced cardiac fibrosis. However, the antifibrotic effects of combined treatment with exercise and ICOS mAb intervention did not exhibit synergistic enhancement.

Nur77 alleviates cardiac fibrosis by upregulating GSK-3β transcription during aging

Cardiac fibrosis is associated with aging, for which no targeted therapies are available. With aging, the levels of nerve growth factor-induced gene B (Nur77) are reduced during cardiac remodelling; however, its role in cardiac fibrosis in aging remains unclear. Here, we found that Nur77 knockout increased cardiac structure abnormalities, systolic and diastolic dysfunction, cardiac hypertrophy, and fibrotic marker expression in 15-month-old mice. Furthermore, Nur77 deficiency induced collagen type I (Col-1) and α-smooth muscle actin overproduction in transforming growth factor beta (TGF-β) treated H9c2 cells, whereas Nur77 overexpression attenuated this effect. Nur77 deficiency in vivo and in vitro downregulated glycogen synthase kinase (GSK)-3β expression and increased β-catenin activity, while its overexpression increased GSK-3β expression. GSK-3β knockdown counteracted the anti-fibrotic effect of Nur77 on TGF-β-treated H9c2 cells. Chromatin immunoprecipitation and luciferase reporter assay results suggested GSK-3β as the direct target of Nur77. Our findings suggest that Nur77 directly initiates GSK-3β transcription and age-related cardiac fibrosis partly through the GSK-3β/β-catenin pathway. This study proposes a novel mechanism for Nur77 regulating cardiac fibrosis and suggests Nur77 as a target for the prevention and treatment of aging-associated cardiac fibrosis and heart failure.

Buyang Huanwu Decoction suppresses cardiac inflammation and fibrosis in mice after myocardial infarction through inhibition of the TLR4 signalling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

It has been reported that cardiac inflammation and fibrosis participate in the development of heart failure (HF) following myocardial infarction (MI). Anti-inflammatory and anti-fibrotic treatments exhibit therapeutic efficacy in MI. Buyang Huanwu Decoction (BYHWD) has cardioprotective properties. However, whether BYHWD regulates cardiac inflammation and fibrosis in HF after MI, and the underlying mechanisms, are still unknown.

AIM OF THE STUDY

This study aimed to explore the effects and potential mechanisms of BYHWD on cardiac inflammation and fibrosis after MI.

MATERIALS AND METHODS

An MI model was constructed through ligation of the left anterior descending coronary artery (LAD) in mice. The cardioprotective effects of BYHWD were determined by echocardiography, Masson trichrome staining, wheat germ agglutinin (WGA) staining and haematoxylin and eosin (HE) staining. The effects of BYHWD on inflammation and fibrosis, and on the TLR4 signalling pathway, were explored through immunohistochemistry (IHC), Western blot (WB), enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) in vivo. Next, the effects of BYHWD on primary cardiac fibroblasts (CFs) inflammation and collagen synthesis, and on the TLR4 signalling pathway, were detected using WB, immunofluorescence (IF) and qRT-PCR in vitro. In addition, the suppression and overexpression of TLR4 in CFs were further explored.

RESULTS

BYHWD dose-dependently reduced cardiac inflammation, fibrosis and ventricular dysfunction. The expression levels of collagen Ⅰ/Ⅲ, IL-1β and IL-18, as well as critical proteins in the TLR4 signalling pathway and the NLRP3 inflammasome, were suppressed by BYHWD in the in vivo experiment. BYHWD inhibited CFs inflammation and collagen synthesis, as well as critical proteins in the TLR4 signalling pathway and the NLRP3 inflammasome, in the in vitro experiment. TLR4 suppression mitigated these inhibitory effects of BYHWD while overexpression of TLR4 markedly reversed these inhibitory effects of BYHWD.

CONCLUSION

BYHWD exerts anti-inflammatory and anti-fibrotic effects in mice after MI, and suppresses CFs inflammation and collagen synthesis through suppression of the TLR4 signalling pathway.

Chitosan Versus Dapagliflozin in a Diabetic Cardiomyopathy Mouse Model

Diabetes mellitus is a metabolic disorder with global economic implications that can lead to complications such as diabetic cardiomyopathy. The aim of this study was to compare the effects of chitosan versus dapagliflozin in mouse diabetic cardiomyopathy. We used 32 C57Bl/6 male mice aged between 8 and 10 weeks, which were randomly divided into Control-without diabetes mellitus (DM), type 1 DM (T1DM), T1DM + Chitosan, and T1DM + Dapapgliflozin groups. We induced diabetes with streptozotocin and treated the animals for 12 weeks. The analysis showed a reduction in intramyocardial fibrosis in the T1DM + Dapapgliflozin compared to T1DM animals. In T1DM + CHIT, a reduction in intramyocardial fibrosis was observed although, accordingly, there was also no significant decrease in blood glucose. The level of oxidative stress was reduced in the groups of treated animals compared to T1DM. All these observed changes in the structure and function of hearts were highlighted in the echocardiographic examination. In the treated groups, there was delayed appearance of left ventricular (LV) hypertrophy, a slight decrease in the ejection fraction of the LV, and an improved diastolic profile. The results demonstrate that chitosan has promising effects on diabetic cardiomyopathy that are comparable to the beneficial effects of dapagliflozin.

CTRP3 inhibits myocardial fibrosis through the P2X7R-NLRP3 inflammasome pathway in SHR rats

BACKGROUND AND PURPOSE

Reducing hypertensive myocardial fibrosis is the fundamental approach to preventing hypertensive ventricular remodelling. C1q/TNF-related protein-3 (CTRP3) is closely associated with hypertension. However, the role and mechanism of CTRP3 in hypertensive myocardial fibrosis are unclear. In this study, we aimed to explore the effect of CTRP3 on hypertensive myocardial fibrosis and the potential mechanism.

METHODS AND RESULTS

WKY and SHR rats were employed, blood pressure, body weight, heart weight, H/BW were measured, and fibrotic-related proteins, CTRP3 and Collagen I were tested in myocardium at 12 and 20 weeks by immunohistochemical staining and Western blotting, respectively. The results showed that compared with the WKY, SBP, DBP, mean arterial pressure and heart rate (HR) were all significantly increased in SHR at 12 and 20 weeks, while heart weight and H/BW were only increased at 20 weeks. Meanwhile, CTRP3 decreased, while Collagen I increased significantly in the SHR rat myocardium at 20 weeks, which compared to the WKY. Moreover, the expression of α-SMA increased from 12 weeks, Collagen I/III and MMP2/9 increased and TIMP-2 decreased until 20 weeks. In order to explore the function and mechanism of CTRP3 in hypertensive fibrosis, Angiotensin II (Ang II) was used to induce hypertension in primary neonatal rat cardiac fibroblasts in vitro . CTRP3 significantly inhibited the Ang II induced activation of fibrotic proteins, purinergic 2X7 receptor (P2X7R)-NLRP3 inflammasome pathway. The P2X7R agonist BzATP significantly exacerbated Ang II-induced NLRP3 inflammasome activation, which was decreased by the P2X7R antagonists A43079, CTRP3 and MCC950.

CONCLUSION

CTRP3 expression was decreased in the myocardium of SHR rats, and exogenous CTRP3 inhibited Ang II-induced fibrosis in cardiac fibroblasts by regulating the P2X7R-NLRP3 inflammasome pathway, suggesting that CTRP3 is a potential drug for alleviating myocardial fibrosis in hypertensive conditions.

TAX1BP1 downregulation by STAT3 in cardiac fibroblasts contributes to diabetes-induced heart failure with preserved ejection fraction

Heart failure (HF) with preserved ejection fraction (HFpEF) is now the most common form of HF and has been reported to be closely related to diabetes. Accumulating evidence suggests that HFpEF patients exhibit cardiac fibrosis. This study investigates whether direct targeted inhibition of the activation of cardiac fibroblasts (CFs), the main effector cells in cardiac fibrosis, improves diabetes-induced HFpEF and elucidates the underlying mechanisms. Twenty-week-old db/db mice exhibited HFpEF, as confirmed by echocardiography and hemodynamic measurements. Proteomics was performed on CFs isolated from the hearts of 20-week-old C57BL/6 and db/db mice. Bioinformatic prediction was used to identify target proteins. Experimental validation was performed in both high glucose (HG)-treated neonatal mouse CFs (NMCFs) and diabetic hearts. TAX1 binding protein 1 (TAX1BP1) was identified as the most significantly differentially expressed protein between 20-week-old C57BL/6 and db/db mice. TAX1BP1 mRNA and protein were markedly downregulated in CFs from diabetic hearts and HG-cultured NMCFs. Overexpression of TAX1BP1 profoundly inhibited HG/diabetes-induced NF-κB nuclear translocation and collagen synthesis in CFs, improved cardiac fibrosis, hypertrophy, inflammation and HFpEF in diabetic mice. Mechanistically, signal transducer and activator of transcription 3 (STAT3), which is phosphorylated and translocated from the cytoplasm into the nucleus under hyperglycemic conditions, bound to TAX1BP1 promoter and blocked TAX1BP1 transcriptional activity, consequently promoting NF-κB nuclear translocation and collagen synthesis in CFs, aggravating cardiac fibrosis, hypertrophy and inflammation, leading to HFpEF in db/db mice. Taken together, our findings demonstrate that targeting regulation of STAT3-TAX1BP1-NF-κB signaling in CFs may be a promising therapeutic approach for diabetes-induced HFpEF.

PCSK9 regulates myofibroblast transformation through the JAK2/STAT3 pathway to regulate fibrosis after myocardial infarction

Cardiac fibrosis is pivotal in the progression of numerous cardiovascular diseases. This phenomenon is hallmarked by an excessive deposition of ECM protein secreted by myofibroblasts, leading to increased myocardial stiffness. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease that belongs to the proprotein-converting enzyme family. It has emerged as a viable therapeutic target for reducing plasma low-density lipoprotein cholesterol. However, the exact mechanism via which PCSK9 impacts cardiac fibrosis remains unclear. In the present research, an increase in circulating PCSK9 protein levels was observed in individuals with myocardial infarction and rat models of myocardial infarction. Moreover, the inhibition of circulating PCSK9 in rats was found to reduce post-infarction fibrosis. In vitro experiments further demonstrated that overexpression of PCSK9 or stimulation by extracellular PCSK9 recombinant protein enhanced the transformation of cardiac fibroblasts to myofibroblasts. This process also elevated collagen Ⅰ, and Ⅲ, as well as α-SMA protein levels. However, these effects were countered when co-incubated with the STAT3 inhibitor S3I-201. This study suggests that PCSK9 may function as a novel regulator of myocardial fibrosis, primarily via the JAK2/STAT3 pathway.

Inhibition of PRKAA/AMPK (Ser485/491) phosphorylation by crizotinib induces cardiotoxicity via perturbing autophagosome-lysosome fusion

Crizotinib, a small-molecule tyrosine kinase inhibitor targeting ALK, MET and ROS1, is the first-line drug for ALK-positive metastatic non-small cell lung cancer and is associated with severe, sometimes fatal, cases of cardiac failure, which increases the risk of mortality. However, the underlying mechanism remains unclear, which causes the lack of therapeutic strategy. We established in vitro and in vivo models for crizotinib-induced cardiotoxicity and found that crizotinib caused left ventricular dysfunction, myocardial injury and pathological remodeling in mice and induced cardiomyocyte apoptosis and mitochondrial injury. In addition, we found that crizotinib prevented the degradation of MET protein by interrupting autophagosome-lysosome fusion and silence of MET or re-activating macroautophagy/autophagy flux rescued the cardiomyocytes death and mitochondrial injury caused by crizotinib, suggesting that impaired autophagy activity is the key reason for crizotinib-induced cardiotoxicity. We further confirmed that recovering the phosphorylation of PRKAA/AMPK (Ser485/491) by metformin re-activated autophagy flux in cardiomyocytes and metformin rescued crizotinib-induced cardiomyocyte injury and cardiac complications. In summary, we revealed a novel mechanism for crizotinib-induced cardiotoxicity, wherein the crizotinib-impaired autophagy process causes cardiomyocyte death and cardiac injury by inhibiting the degradation of MET protein, demonstrated a new function of impeded autophagosome-lysosome fusion in drugs-induced cardiotoxicity, pointed out the essential role of the phosphorylation of PRKAA (Ser485/491) in autophagosome-lysosome fusion and confirmed metformin as a potential therapeutic strategy for crizotinib-induced cardiotoxicity.Abbreviations and Acronyms: AAV: adeno-associated virus; ACAC/ACC: acetyl-Co A carboxylase; AMP: adenosine monophosphate; AMPK: AMP-activated protein kinase; ATG5: autophagy related 5; ATG7: autophagy related 7; CHX: cycloheximide; CKMB: creatine kinase myocardial band; CQ: chloroquine; c-PARP: cleaved poly (ADP-ribose) polymerase; DAPI: 4'6-diamidino-2-phenylindole; EF: ejection fraction; FOXO: forkhead box O; FS: fractional shortening; GSEA: gene set enrichment analysis; H&E: hematoxylin and eosin; HF: heart failure; HW: TL: ratio of heart weight to tibia length; IR: ischemia-reperfusion; KEGG: Kyoto encyclopedia of genes and genomes; LAMP2: lysosomal-associated membrane protein 2; LDH: lactate dehydrogenase; MCMs: mouse cardiomyocytes; MMP: mitochondrial membrane potential; mtDNA: mitochondrial DNA; MYH6: myosin, heavy peptide 6, cardiac muscle, alpha; MYH7: myosin, heavy peptide 7, cardiac muscle, beta; NPPA: natriuretic peptide type A; NPPB: natriuretic peptide type B; PI: propidium iodide; PI3K: phosphoinositide 3-kinase; PRKAA/AMPKα: protein kinase AMP-activated catalytic subunit alpha; qPCR: quantitative real-time PCR; SD: standard deviation; SRB: sulforhodamine B; TKI: tyrosine kinase inhibitor; WGA: wheat germ agglutinin.

Molecular evolution of the heat shock protein family and the role of HSP30 in immune response and wound healing in lampreys (Lethenteron reissneri)

Heat shock proteins (HSPs) are molecular chaperones that ubiquitously exist in various organisms and play essential roles in protein folding, transport, and expression. While most HSPs are highly conserved across species, a few HSPs are evolutionarily distinct in some species and may have unique functions. To explore the evolutionary history of the vertebrate HSP family, we identify members of the HSP family at the genome-wide level in lampreys (Lethenteron reissneri), a living representative of jawless vertebrates diverged from jawed vertebrates over 500 million years ago. The phylogenetic analysis reveals that the lamprey HSP family contains HSP90a1, HSP90a2, HSC70, HSP60, HSP30, HSP27, HSP17, and HSP10, which have a primitive status in the molecular evolution of vertebrate HSPs. Transcriptome analysis reveals the expression distribution of members of the HSP family in various tissues of lampreys. It is shown that HSP30, normally found in birds, amphibians, and fish, is also present in lampreys, with remarkable expansion of HSP30 gene copies in the lamprey genome. The transcription of HSP30 is significantly induced in leukocytes and heart of lampreys during various pathogens or poly(I:C) stimulation, indicating that HSP30 may be involved in the immune defense of lampreys in response to bacterial or viral infection. Immunohistochemistry demonstrates significantly increased HSP30 expression in subcutaneous muscle tissue after skin injury in lamprey models of wound repair. Furthermore, transcriptome analysis shows that ectopic expression of HSP30 in 3T3-L1 fibroblasts affect the expression of genes related to the PI3K-AKT signaling pathway, suggesting that HSP30 could serves as a negative regulator of fibrosis. These results indicate that HSP30 may play a critical role in facilitating the process of lamprey skin repair following injury. This study provides new insights into the origin and evolution of the HSP gene family in vertebrates and offers valuable clues to reveal the important role of HSP30 in immune defense and wound healing of lampreys.

In Vitro Mechanical Stimulation to Reproduce the Pathological Hallmarks of Human Cardiac Fibrosis on a Beating Chip and Predict The Efficacy of Drugs and Advanced Therapies

Cardiac fibrosis is one of the main causes of heart failure, significantly contributing to mortality. The discovery and development of effective therapies able to heal fibrotic pathological symptoms thus remain of paramount importance. Micro-physiological systems (MPS) are recently introduced as promising platforms able to accelerate this finding. Here a 3D in vitro model of human cardiac fibrosis, named uScar, is developed by imposing a cyclic mechanical stimulation to human atrial cardiac fibroblasts (AHCFs) cultured in a 3D beating heart-on-chip and exploited to screen drugs and advanced therapeutics. The sole provision of a cyclic 10% uniaxial strain at 1 Hz to the microtissues is sufficient to trigger fibrotic traits, inducing a consistent fibroblast-to-myofibroblast transition and an enhanced expression and production of extracellular matrix (ECM) proteins. Standard of care anti-fibrotic drugs (i.e., Pirfenidone and Tranilast) are confirmed to be efficient in preventing the onset of fibrotic traits in uScar. Conversely, the mechanical stimulation applied to the microtissues limit the ability of a miRNA therapy to directly reprogram fibroblasts into cardiomyocytes (CMs), despite its proved efficacy in 2D models. Such results demonstrate the importance of incorporating in vivo-like stimulations to generate more representative 3D in vitro models able to predict the efficacy of therapies in patients.

AMPK signaling inhibits the differentiation of myofibroblasts: impact on age-related tissue fibrosis and degeneration

Disruption of the extracellular matrix (ECM) and an accumulation of fibrotic lesions within tissues are two of the distinctive hallmarks of the aging process. Tissue fibroblasts are mesenchymal cells which display an impressive plasticity in the regulation of ECM integrity and thus on tissue homeostasis. Single-cell transcriptome studies have revealed that tissue fibroblasts exhibit a remarkable heterogeneity with aging and in age-related diseases. Excessive stress and inflammatory insults induce the differentiation of fibroblasts into myofibroblasts which are fusiform contractile cells and abundantly secrete the components of the ECM and proteolytic enzymes as well as many inflammatory mediators. Detrimental stresses can also induce the transdifferentiation of certain mesenchymal and myeloid cells into myofibroblasts. Interestingly, many age-related stresses, such as oxidative and endoplasmic reticulum stresses, ECM stiffness, inflammatory mediators, telomere shortening, and several alarmins from damaged cells are potent inducers of myofibroblast differentiation. Intriguingly, there is convincing evidence that the signaling pathways stimulated by the AMP-activated protein kinase (AMPK) are potent inhibitors of myofibroblast differentiation and accordingly AMPK signaling reduces fibrotic lesions within tissues, e.g., in age-related cardiac and pulmonary fibrosis. AMPK signaling is not only an important regulator of energy metabolism but it is also able to control cell fate determination and many functions of the immune system. It is known that AMPK signaling can delay the aging process via an integrated signaling network. AMPK signaling inhibits myofibroblast differentiation, e.g., by suppressing signaling through the TGF-β, NF-κB, STAT3, and YAP/TAZ pathways. It seems that AMPK signaling can alleviate age-related tissue fibrosis and degeneration by inhibiting the differentiation of myofibroblasts.

SIRT3/6: an amazing challenge and opportunity in the fight against fibrosis and aging

Fibrosis is a typical aging-related pathological process involving almost all organs, including the heart, kidney, liver, lung, and skin. Fibrogenesis is a highly orchestrated process defined by sequences of cellular response and molecular signals mechanisms underlying the disease. In pathophysiologic conditions associated with organ fibrosis, a variety of injurious stimuli such as metabolic disorders, epigenetic changes, and aging may induce the progression of fibrosis. Sirtuins protein is a kind of deacetylase which can regulate cell metabolism and participate in a variety of cell physiological functions. In this review, we outline our current understanding of common principles of fibrogenic mechanisms and the functional role of SIRT3/6 in aging-related fibrosis. In addition, sequences of novel protective strategies have been identified directly or indirectly according to these mechanisms. Here, we highlight the role and biological function of SIRT3/6 focus on aging fibrosis, as well as their inhibitors and activators as novel preventative or therapeutic interventions for aging-related tissue fibrosis.

Hypoxia-inducible factor-1: Regulatory mechanisms and drug therapy in myocardial infarction

Myocardial infarction (MI), an acute cardiovascular disease characterized by coronary artery blockage, inadequate blood supply, and subsequent ischemic necrosis of the myocardium, is one of the leading causes of death. The cellular, physiological, and pathological responses following MI are complex, involving multiple intertwined pathological mechanisms. Hypoxia-inducible factor-1 (HIF-1), a crucial regulator of hypoxia, plays a significant role in of the development of MI by modulating the behavior of various cells such as cardiomyocytes, endothelial cells, macrophages, and fibroblasts under hypoxic conditions. HIF-1 regulates various post-MI adaptive reactions to acute ischemia and hypoxia through various mechanisms. These mechanisms include angiogenesis, energy metabolism, oxidative stress, inflammatory response, and ventricular remodeling. With its crucial role in MI, HIF-1 is expected to significantly influence the treatment of MI. However, the drugs available for the treatment of MI targeting HIF-1 are currently limited, and most contain natural compounds. The development of precision-targeted drugs modulating HIF-1 has therapeutic potential for advancing MI treatment research and development. This study aimed to summarize the regulatory role of HIF-1 in the pathological responses of various cells following MI, the diverse mechanisms of action of HIF-1 in MI, and the potential drugs targeting HIF-1 for treating MI, thus providing the theoretical foundations for potential clinical therapeutic targets.

Downregulation of B4GALT5 attenuates cardiac fibrosis through Lumican and Akt/GSK-3β/β-catenin pathway

Virtually all forms of cardiac disease exhibit cardiac fibrosis as a common trait, which ultimately leads to adverse ventricular remodeling and heart failure. To improve the prognosis of heart disease, it is crucial to halt the progression of cardiac fibrosis. Protein function is intricately linked with protein glycosylation, a vital post-translational modification. As a fundamental member of the β1,4-galactosyltransferase gene family (B4GALT), β1,4-galactosyltransferase V (B4GALT5) is associated with various disorders. In this study, significant levels of B4GALT5 expression were observed in cardiac fibrosis induced by transverse aortic constriction (TAC) or TGFβ1 and the activation of cardiac fibroblasts (CFs). Subsequently, by administering AAV9-shB4GALT5 injections to TAC animals, we were able to demonstrate that in vivo B4GALT5 knockdown decreased the transformation of CFs into myofibroblasts (myoFBs) and reduced the deposition of cardiac collagen fibers. In vitro tests revealed the same results. Conversely, both in vivo and in vitro experiments indicated that overexpression of B4GALT5 stimulates CFs activation and exacerbates cardiac fibrosis. Initially, we elucidated the primary mechanism by which B4GALT5 regulates the Akt/GSK-3β/β-catenin pathway and directly interacts with laminin, thereby affecting cardiac fibrosis. Our findings demonstrate that B4GALT5 promotes cardiac fibrosis through the Akt/GSK-3β/β-catenin pathway and reveal laminin as the target protein of B4GALT5.

The underlying mechanisms of DNA methylation in high salt memory in hypertensive vascular disease

This study demonstrates the effect and DNA methylation-related mechanisms of a high-salt diet and salt memory-induced hypertension and vasculopathy. Thirty Sprague Dawley rats were randomly divided into a control (CON) group (n = 6) and a modeling group (n = 24). A 12% NaCl solution (1 mL/100 g) was intragastrically administered for 60 consecutive days for modeling. An increase in blood pressure up to 140 mmHg was considered successful modeling. Twelve of fifteen successfully modeled rats were randomly selected and divided into a High Salt Diet (HSD) group and a High Salt Memory (HSM) group (n = 6). Rats in HSD group were intragastrically administered a 12% NaCl solution, while rats in HSM group were administered a 3% NaCl solution twice a day for 30 days. At the end of the intervention, blood pressure and the serum levels of ET-1, NO, TNF-α and IL-1β were measured. RRBS-heavy sulfite sequencing technology was selected for DNA methylation analysis. The systolic blood pressure of rats in the HSD group and HSM group was significantly higher than that in the CON group. Compared with those in the CON group, the serum levels of ET-1 in the HSM group and the serum levels of NO in the HSD group and HSM group were significantly increased. The methylation level of the CON group was lower than that of the HSD group and the HSM group, and there was no significant difference between the HSD group and the HSM group. The methylation level of Myoz3 was downregulated in the HSD group and HSM group. The methylation level of Fgd3 were upregulated in HSD group and downregulated in the HSM group. The methylation levels of AC095693.1, Adamts3, PDGFA and PDGFRα were downregulated in the HSD group and upregulated in the HSM group. According to the GO database, the differentially methylated genes were significantly enriched in the coordination of cell function, genetic development, and RNA transcription. There were three main metabolic pathways that were enriched in the differentially expressed genes between the groups: the PI3K-Akt signaling pathway, MAPK signaling pathway, and Hippo signaling pathway. Excessive salt intake may cause hypertension and vascular damage, and this damage may continue after the reduction of salt intake. Therefore, salt memory phenomenon exists, and this memory effect may be correlated with the levels of DNA methylation.

Effects of scutellarin on the mechanism of cardiovascular diseases: a review

Cardiovascular diseases represent a significant worldwide problem, jeopardizing individuals' physical and mental wellbeing as well as their quality of life as a result of their widespread incidence and fatality. With the aging society, the occurrence of Cardiovascular diseases is progressively rising each year. However, although drugs developed for treating Cardiovascular diseases have clear targets and proven efficacy, they still carry certain toxic and side effect risks. Therefore, finding safe, effective, and practical treatment options is crucial. Scutellarin is the primary constituent of Erigeron breviscapus (Vant.) Hand-Mazz. This article aims to establish a theoretical foundation for the creation and use of secure, productive, and logical medications for Scutellarin in curing heart-related illnesses. Additionally, the examination and analysis of the signal pathway and its associated mechanisms with regard to the employment of SCU in treating heart diseases will impart innovative resolving concepts for the treatment and prevention of Cardiovascular diseases.

Salvianolic Acid B Inhibits Myocardial Fibrosis during Diabetic Cardiomyopathy via Suppressing TRPC6 and TGF‐β/Smad3 Pathway

Salvianolic acid B (Sal B), the main water‐soluble polyphenolic constituent of Danshen, is noted for its anti‐inflammatory, antioxidant, and antiapoptotic properties, particularly in cardiovascular protection. However, the mechanisms by which Sal B affects myocardial fibrosis require further investigation. In vivo, we established a diabetic mouse model using a high‐fat diet and intraperitoneal streptozotocin (STZ) administration. Mice were then treated with Sal B, the transient receptor potential channel 6 (TRPC6) inducers, or their combination. Upregulation of TRPC6 worsened myocardial pathology, leading to cardiac hypertrophy and collagen fiber deposition. In vitro, transforming growth factor (TGF)‐β1 induced transdifferentiation of cardiac fibroblasts into myofibroblasts, creating a myofibroblast cell model. Sal B, TRPC6 inducers, or their combination were administered. TRPC6 upregulation increased procollagen type I C‐terminal propeptide (PICP) and procollagen type III N‐terminal propeptide (PIIINP) secretion, promoting myofibroblast proliferation and migration. Our study indicates that TRPC6 expression is upregulated in myocardial fibrosis, enhancing TGF‐β/Smad3 signaling and promoting collagen I (COL‐1) synthesis. Sal B inhibited abnormal TRPC6 expression and TGF‐β/Smad3 activation, mitigating these effects. Thus, Sal B alleviates myocardial fibrosis in diabetes by modulating TRPC6 expression and TGF‐β/Smad3 signaling pathway.

Assessing the association between genetic and phenotypic features of dilated cardiomyopathy and outcome in patients with coronary artery disease

AIMS

To examine the relevance of genetic and cardiovascular magnetic resonance (CMR) features of dilated cardiomyopathy (DCM) in individuals with coronary artery disease (CAD).

METHODS AND RESULTS

This study includes two cohorts. First, individuals with CAD recruited into the UK Biobank (UKB) were evaluated. Second, patients with CAD referred to a tertiary centre for evaluation with late gadolinium enhancement (LGE)-CMR were recruited (London cohort); patients underwent genetic sequencing as part of the research protocol and long-term follow-up. From 31 154 individuals with CAD recruited to UKB, rare pathogenic variants in DCM genes were associated with increased risk of death or major adverse cardiac events (hazard ratio 1.57, 95% confidence interval [CI] 1.22-2.01, p < 0.001). Of 1619 individuals with CAD included from the UKB CMR substudy, participants with a rare variant in a DCM-associated gene had lower left ventricular ejection fraction (LVEF) compared to genotype negative individuals (mean 47 ± 10% vs. 57 ± 8%, p < 0.001). Of 453 patients in the London cohort, 63 (14%) had non-infarct pattern LGE (NI-LGE) on CMR. Patients with NI-LGE had lower LVEF (mean 38 ± 18% vs. 48 ± 16%, p < 0.001) compared to patients without NI-LGE, with no significant difference in the burden of rare protein altering variants in DCM-associated genes between groups (9.5% vs. 6.7%, odds ratio 1.5, 95% CI 0.4-4.3, p = 0.4). NI-LGE was not independently associated with adverse clinical outcomes.

CONCLUSION

Rare pathogenic variants in DCM-associated genes impact left ventricular remodelling and outcomes in stable CAD. NI-LGE is associated with adverse remodelling but is not an independent predictor of outcome and had no rare genetic basis in our study.

Molecular Pathways and Animal Models of Cardiomyopathies

Cardiomyopathies are a heterogeneous group of disorders of the heart muscle that ultimately result in congestive heart failure. Rapid progress in genetics, molecular and cellular biology with breakthrough innovative genetic-engineering techniques, such as next-generation sequencing and multiomics platforms, stem cell reprogramming, as well as novel groundbreaking gene-editing systems over the past 25 years has greatly improved the understanding of pathogenic signaling pathways in inherited cardiomyopathies. This chapter will focus on intracellular and intercellular molecular signaling pathways that are activated by a genetic insult in cardiomyocytes to maintain tissue and organ level regulation and resultant cardiac remodeling in certain forms of cardiomyopathies. In addition, animal models of different clinical forms of human cardiomyopathies with their summaries of triggered key molecules and signaling pathways will be described.

Oncostatin M/Oncostatin M Receptor Signal Induces Radiation-Induced Heart Fibrosis by Regulating SMAD4 in Fibroblast

PURPOSE

Radiation-induced heart fibrosis (RIHF) is a severe consequence of radiation-induced heart damage (RIHD) leading to impaired cardiac function. The involvement of oncostatin M (OSM) and its receptor (OSMR) in RIHD remains unclear. This study aimed to investigate the specific mechanism of OSM/OSMR in RIHF/RIHD.

METHODS AND MATERIALS

RNA sequencing was performed on heart tissues from a RIHD mouse model. OSM levels were assessed in serum samples obtained from patients receiving thoracic radiation therapy (RT), as well as in RIHF mouse heart tissues and serum using enzyme-linked immunosorbent assay. Fiber activation was evaluated through costimulation of primary cardiac fibroblasts and NIH3T3 cells with RT and OSM, using Western blotting, immunofluorescence, and quantitative Polymerase Chain Reaction (qPCR). Adeno-associated virus serotype 9-mediated overexpression or silencing of OSM specifically in the heart was performed in vivo to assess cardiac fibrosis levels by transthoracic echocardiography and pathologic examination. The regulatory mechanism of OSM on the transcription level of SMAD4 was further explored in vitro using mass spectrometric analysis, chromatin immunoprecipitation-qPCR, and DNA pull-down.

RESULTS

OSM levels were elevated in the serum of patients after thoracic RT as well as in RIHF mouse cardiac endothelial cells and mouse serum. The OSM rate (post-RT/pre-RT) and the heart exposure dose in RT patients showed a positive correlation. Silencing OSMR in RIHF mice reduced fibrosis, while OSMR overexpression increased fibrotic responses. Furthermore, increased OSM promoted histone acetylation (H3K27ac) in the SMAD4 promoter region, influencing SMAD4 transcription and subsequently enhancing fibrotic response.

CONCLUSIONS

The findings demonstrated that OSM/OSMR signaling promotes SMAD4 transcription in cardiac fibroblasts through H3K27 hyperacetylation, thereby promoting radiation-induced cardiac fibrosis and manifestations of RIHD.

Epigenetic signatures in cardiac fibrosis: Focusing on noncoding RNA regulators as the gatekeepers of cardiac fibroblast identity

Cardiac fibroblasts play a pivotal role in cardiac fibrosis by transformation of fibroblasts into myofibroblasts, which synthesis and secrete a large number of extracellular matrix proteins. Ultimately, this will lead to cardiac wall stiffness and impaired cardiac performance. The epigenetic regulation and fate reprogramming of cardiac fibroblasts has been advanced considerably in recent decades. Non coding RNAs (microRNAs, lncRNAs, circRNAs) regulate the functions and behaviors of cardiac fibroblasts, including proliferation, migration, phenotypic transformation, inflammation, pyroptosis, apoptosis, autophagy, which can provide the basis for novel targeted therapeutic treatments that abrogate activation and inflammation of cardiac fibroblasts, induce different death pathways in cardiac fibroblasts, or make it sensitive to established pathogenic cells targeted cytotoxic agents and biotherapy. This review summarizes our current knowledge in this field of ncRNAs function in epigenetic regulation and fate determination of cardiac fibroblasts as well as the details of signaling pathways contribute to cardiac fibrosis. Moreover, we will comment on the emerging landscape of lncRNAs and circRNAs function in regulating signal transduction pathways, gene translation processes and post-translational regulation of gene expression in cardiac fibroblast. In the end, the prospect of cardiac fibroblasts targeted therapy for cardiac fibrosis based on ncRNAs is discussed.

Oleanolic acid derivative alleviates cardiac fibrosis through inhibiting PTP1B activity and regulating AMPK/TGF-β/Smads pathway

Cardiac fibrosis (CF) in response to persistent exogenous stimuli or myocardial injury results in cardiovascular diseases (CVDs). Protein tyrosine phosphatase 1B (PTP1B) can promote collagen deposition through regulating AMPK/TGF-β/Smads signaling pathway, and PTP1B knockout improves cardiac dysfunction against overload-induced heart failure. Oleanolic acid (OA) has been proven to be an inhibitor of PTP1B, and its anti-cardiac remodeling effects have been validated in different mouse models. To improve the bioactivity of OA and to clarify whether OA derivatives with stronger inhibition of PTP1B activity have greater prevention of cardiac remodeling than OA, four new OA derivatives were synthesized and among them, we found that compound B had better effects than OA in inhibiting cardiac fibrosis both in vivo in the isoproterenol (ISO)-induced mouse cardiac fibrosis and in vitro in the TGF-β/ISO-induced 3T3 cells. Combining with the results of molecular docking, surface plasmon resonance and PTP1B activity assay, we reported that OA and compound B directly bound to PTP1B and inhibited its activity, and that compound B showed comparable binding capability but stronger inhibitory effect on PTP1B activity than OA. Moreover, compound B presented much greater effects on AMPK activation and TGF-β/Smads inhibition than OA. Taken together, OA derivative compound B more significantly alleviated cardiac fibrosis than OA through much greater inhibition of PTP1B activity and thus much stronger regulation of AMPK/TGF-β/Smads signaling pathway.

Mechanisms and therapeutic strategies of extracellular vesicles in cardiovascular diseases

Cardiovascular disease (CVD) significantly impacts global society since it is the leading cause of death and disability worldwide, and extracellular vesicle (EV)-based therapies have been extensively investigated. EV delivery is involved in mediating the progression of CVDs and has great potential to be biomarker and therapeutic molecular carrier. Besides, EVs from stem cells and cardiac cells can effectively protect the heart from various pathologic conditions, and then serve as an alternative treatment for CVDs. Moreover, the research of using EVs as delivery carriers of therapeutic molecules, membrane engineering modification of EVs, or combining EVs with biomaterials further improves the application potential of EVs in clinical treatment. However, currently there are only a few articles summarizing the application of EVs in CVDs. This review provides an overview of the role of EVs in the pathogenesis and diagnosis of CVDs. It also focuses on how EVs promote the repair of myocardial injury and therapeutic methods of CVDs. In conclusion, it is of great significance to review the research on the application of EVs in the treatment of CVDs, which lays a foundation for further exploration of the role of EVs, and clarifies the prospect of EVs in the treatment of myocardial injury.