Genetic manipulation of periostin expression reveals a role in cardiac hypertrophy and ventricular remodeling

Nanomedicine: A great boon for cardiac regenerative medicine

Cardiovascular disease (CVD) represents a significant global health challenge, remaining the leading cause of illness and mortality worldwide. The adult heart's limited regenerative capacity poses a major obstacle in repairing extensive damage caused by conditions like myocardial infarction. In response to these challenges, nanomedicine has emerged as a promising field aimed at improving treatment outcomes through innovative drug delivery strategies. Nanocarriers, such as nanoparticles (NPs), offer a revolutionary approach by facilitating targeted delivery of therapeutic agents directly to the heart. This precise delivery system holds immense potential for treating various cardiac conditions by addressing underlying mechanisms such as inflammation, oxidative stress, cell death, extracellular matrix remodeling, prosurvival signaling, and angiogenic pathways associated with ischemia-reperfusion injury. In this review, we provide a concise summary of the fundamental mechanisms involved in cardiac remodeling and regeneration. We explore how nanoparticle-based drug delivery systems can effectively target the afore-mentioned mechanisms. Furthermore, we discuss clinical trials that have utilized nanoparticle-based drug delivery systems specifically designed for cardiac applications. These trials demonstrate the potential of nanomedicine in clinical settings, paving the way for future advancements in cardiac therapeutics through precise and efficient drug delivery. Overall, nanomedicine holds promise in revolutionizing the treatment landscape of cardiovascular diseases by offering targeted and effective therapeutic strategies that address the complex pathophysiology of cardiac injuries.

Clinical-transcriptional prioritization of the circulating proteome in human heart failure

Given expanding studies in epidemiology and disease-oriented human studies offering hundreds of associations between the human "ome" and disease, prioritizing molecules relevant to disease mechanisms among this growing breadth is important. Here, we link the circulating proteome to human heart failure (HF) propensity (via echocardiographic phenotyping and clinical outcomes) across the lifespan, demonstrating key pathways of fibrosis, inflammation, metabolism, and hypertrophy. We observe a broad array of genes encoding proteins linked to HF phenotypes and outcomes in clinical populations dynamically expressed at a transcriptional level in human myocardium during HF and cardiac recovery (several in a cell-specific fashion). Many identified targets do not have wide precedent in large-scale genomic discovery or human studies, highlighting the complementary roles for proteomic and tissue transcriptomic discovery to focus epidemiological targets to those relevant in human myocardium for further interrogation.

Coordinated Tbx3 / Tbx5 transcriptional control of the adult ventricular conduction system

The cardiac conduction system (CCS) orchestrates the electrical impulses that enable coordinated contraction of the cardiac chambers. The T-box transcription factors TBX3 and TBX5 are required for cardiac conduction system development and associated with overlapping and distinct human cardiac conduction system diseases. We evaluated the coordinated role of Tbx3 and Tbx5 in the murine ventricular conduction system (VCS). We engineered a compound Tbx3:Tbx5 conditional knockout allele for both genes located in cis on mouse chromosome 5. Conditional deletion of both T-box transcriptional factors in the ventricular conduction system, using the VCS-specific Mink:Cre, caused loss of VCS function and molecular identity. Combined Tbx3 and Tbx5 deficiency in the adult VCS led to conduction defects, including prolonged PR and QRS intervals and elevated susceptibility to ventricular tachycardia. These electrophysiologic defects occurred prior to detectable alterations in cardiac contractility or histologic morphology, indicative of a primary conduction system defect. Tbx3:Tbx5 double knockout VCS cardiomyocytes revealed a transcriptional shift towards non-CCS-specialized working myocardium, suggesting reprogramming of their cellular identity. Furthermore, optical mapping revealed a loss of VCS-specific conduction system propagation. Collectively, these findings indicate that Tbx3 and Tbx5 coordinate to control VCS molecular fate and function, with implications for understanding cardiac conduction disorders in humans.

Myocardial fibrosis from the perspective of the extracellular matrix: mechanisms to clinical impact

Fibrosis is defined by the excessive accumulation of extracellular matrix (ECM) and constitutes a central pathophysiological process that underlies tissue dysfunction, across organs, in multiple chronic diseases and during aging. Myocardial fibrosis is a key contributor to dysfunction and failure in numerous diseases of the heart and is a strong predictor of poor clinical outcome and mortality. The excess structural and matricellular ECM proteins deposited by cardiac fibroblasts, is found between cardiomyocytes (interstitial fibrosis), in focal areas where cardiomyocytes have died (replacement fibrosis), and around vessels (perivascular fibrosis). Although myocardial fibrosis has important clinical prognostic value, access to cardiac tissue biopsies for histological evaluation is limited. Despite challenges with sensitivity and specificity, cardiac magnetic resonance imaging (CMR) is the most applicable diagnostic tool in the clinic, and the scientific community is currently actively searching for blood biomarkers reflecting myocardial fibrosis, to complement the imaging techniques. The lack of mechanistic insights into specific pro- and anti-fibrotic molecular pathways has hampered the development of effective treatments to prevent or reverse myocardial fibrosis. Development and implementation of anti-fibrotic therapies is expected to improve patient outcomes and is an urgent medical need. Here, we discuss the importance of the ECM in the heart, the central role of fibrosis in heart disease, and mechanistic pathways likely to impact clinical practice with regards to diagnostics of myocardial fibrosis, risk stratification of patients, and anti-fibrotic therapy.

Protein glycosylation in cardiovascular health and disease

Protein glycosylation, which involves the attachment of carbohydrates to proteins, is one of the most abundant protein co-translational and post-translational modifications. Advances in technology have substantially increased our knowledge of the biosynthetic pathways involved in protein glycosylation, as well as how changes in glycosylation can affect cell function. In addition, our understanding of the role of protein glycosylation in disease processes is growing, particularly in the context of immune system function, infectious diseases, neurodegeneration and cancer. Several decades ago, cell surface glycoproteins were found to have an important role in regulating ion transport across the cardiac sarcolemma. However, with very few exceptions, our understanding of how changes in protein glycosylation influence cardiovascular (patho)physiology remains remarkably limited. Therefore, in this Review, we aim to provide an overview of N-linked and O-linked protein glycosylation, including intracellular O-linked N-acetylglucosamine protein modification. We discuss our current understanding of how all forms of protein glycosylation contribute to normal cardiovascular function and their roles in cardiovascular disease. Finally, we highlight potential gaps in our knowledge about the effects of protein glycosylation on the heart and vascular system, highlighting areas for future research.

Periosteal skeletal stem cells can migrate into the bone marrow and support hematopoiesis after injury

Skeletal stem cells have been isolated from various tissues, including periosteum and bone marrow, where they exhibit key functions in bone biology and hematopoiesis, respectively. The role of periosteal skeletal stem cells in bone regeneration and healing has been extensively studied, but their ability to contribute to the bone marrow stroma is still under debate. In the present study, we characterized a whole bone transplantation model that mimics the initial bone marrow necrosis and fatty infiltration seen after injury. Using this model and a lineage tracing approach, we observed the migration of periosteal skeletal stem cells into the bone marrow after transplantation. Once in the bone marrow, periosteal skeletal stem cells are phenotypically and functionally reprogrammed into bone marrow mesenchymal stem cells that express high levels of hematopoietic stem cell niche factors such as Cxcl12 and Kitl. In addition, using in-vitro and in-vivo approaches, we found that periosteal skeletal stem cells are more resistant to acute stress than bone marrow mesenchymal stem cells. These results highlight the plasticity of periosteal skeletal stem cells and their potential role in bone marrow regeneration after bone marrow injury.

The Role of Vimentin in Human Corneal Fibroblast Spreading and Myofibroblast Transformation

Vimentin has been reported to play diverse roles in cell processes such as spreading, migration, cell-matrix adhesion, and fibrotic transformation. Here, we assess how vimentin impacts cell spreading, morphology, and myofibroblast transformation of human corneal fibroblasts. Overall, although knockout (KO) of vimentin did not dramatically impact corneal fibroblast spreading and mechanical activity (traction force), cell elongation in response to PDGF was reduced in vimentin KO cells as compared to controls. Blocking vimentin polymerization using Withaferin had even more pronounced effects on cell spreading and also inhibited cell-induced matrix contraction. Furthermore, although absence of vimentin did not completely block TGFβ-induced myofibroblast transformation, the degree of transformation and amount of αSMA protein expression was reduced. Proteomics showed that vimentin KO cells cultured in TGFβ had a similar pattern of protein expression as controls. One exception included periostin, an ECM protein associated with wound healing and fibrosis in other cell types, which was highly expressed only in Vim KO cells. We also demonstrate for the first time that LRRC15, a protein previously associated with myofibroblast transformation of cancer-associated fibroblasts, is also expressed by corneal myofibroblasts. Interestingly, proteins associated with LRRC15 in other cell types, such as collagen, fibronectin, β1 integrin and α11 integrin, were also upregulated. Overall, our data show that vimentin impacts both corneal fibroblast spreading and myofibroblast transformation. We also identified novel proteins that may regulate corneal myofibroblast transformation in the presence and/or absence of vimentin.

Harnessing the regenerative potential of interleukin11 to enhance heart repair

Balancing between regenerative processes and fibrosis is crucial for heart repair, yet strategies regulating this balance remain a barrier to developing therapies. While Interleukin11 (IL11) is known as a fibrotic factor, its contribution to heart regeneration is poorly understood. We uncovered that il11a, an Il11 homolog in zebrafish, can trigger robust regenerative programs in zebrafish hearts, including cardiomyocytes proliferation and coronary expansion, even in the absence of injury. However, prolonged il11a induction in uninjured hearts causes persistent fibroblast emergence, resulting in fibrosis. While deciphering the regenerative and fibrotic effects of il11a, we found that il11-dependent fibrosis, but not regeneration, is mediated through ERK activity, suggesting to potentially uncouple il11a dual effects on regeneration and fibrosis. To harness the il11a's regenerative ability, we devised a combinatorial treatment through il11a induction with ERK inhibition. This approach enhances cardiomyocyte proliferation with mitigated fibrosis, achieving a balance between regenerative processes and fibrosis. Thus, we unveil the mechanistic insights into regenerative il11 roles, offering therapeutic avenues to foster cardiac repair without exacerbating fibrosis.

Repair of the Infarcted Heart: Cellular Effectors, Molecular Mechanisms and Therapeutic Opportunities

The adult mammalian heart has limited endogenous regenerative capacity and heals through the activation of inflammatory and fibrogenic cascades that ultimately result in the formation of a scar. After infarction, massive cardiomyocyte death releases a broad range of damage-associated molecular patterns that initiate both myocardial and systemic inflammatory responses. TLRs (toll-like receptors) and NLRs (NOD-like receptors) recognize damage-associated molecular patterns (DAMPs) and transduce downstream proinflammatory signals, leading to upregulation of cytokines (such as interleukin-1, TNF-α [tumor necrosis factor-α], and interleukin-6) and chemokines (such as CCL2 [CC chemokine ligand 2]) and recruitment of neutrophils, monocytes, and lymphocytes. Expansion and diversification of cardiac macrophages in the infarcted heart play a major role in the clearance of the infarct from dead cells and the subsequent stimulation of reparative pathways. Efferocytosis triggers the induction and release of anti-inflammatory mediators that restrain the inflammatory reaction and set the stage for the activation of reparative fibroblasts and vascular cells. Growth factor-mediated pathways, neurohumoral cascades, and matricellular proteins deposited in the provisional matrix stimulate fibroblast activation and proliferation and myofibroblast conversion. Deposition of a well-organized collagen-based extracellular matrix network protects the heart from catastrophic rupture and attenuates ventricular dilation. Scar maturation requires stimulation of endogenous signals that inhibit fibroblast activity and prevent excessive fibrosis. Moreover, in the mature scar, infarct neovessels acquire a mural cell coat that contributes to the stabilization of the microvascular network. Excessive, prolonged, or dysregulated inflammatory or fibrogenic cascades accentuate adverse remodeling and dysfunction. Moreover, inflammatory leukocytes and fibroblasts can contribute to arrhythmogenesis. Inflammatory and fibrogenic pathways may be promising therapeutic targets to attenuate heart failure progression and inhibit arrhythmia generation in patients surviving myocardial infarction.

Modified mRNA-Mediated CCN5 Gene Transfer Ameliorates Cardiac Dysfunction and Fibrosis without Adverse Structural Remodeling

Modified mRNAs (modRNAs) are an emerging delivery method for gene therapy. The success of modRNA-based COVID-19 vaccines has demonstrated that modRNA is a safe and effective therapeutic tool. Moreover, modRNA has the potential to treat various human diseases, including cardiac dysfunction. Acute myocardial infarction (MI) is a major cardiac disorder that currently lacks curative treatment options, and MI is commonly accompanied by fibrosis and impaired cardiac function. Our group previously demonstrated that the matricellular protein CCN5 inhibits cardiac fibrosis (CF) and mitigates cardiac dysfunction. However, it remains unclear whether early intervention of CF under stress conditions is beneficial or more detrimental due to potential adverse effects such as left ventricular (LV) rupture. We hypothesized that CCN5 would alleviate the adverse effects of myocardial infarction (MI) through its anti-fibrotic properties under stress conditions. To induce the rapid expression of CCN5, ModRNA-CCN5 was synthesized and administrated directly into the myocardium in a mouse MI model. To evaluate CCN5 activity, we established two independent experimental schemes: (1) preventive intervention and (2) therapeutic intervention. Functional analyses, including echocardiography and magnetic resonance imaging (MRI), along with molecular assays, demonstrated that modRNA-mediated CCN5 gene transfer significantly attenuated cardiac fibrosis and improved cardiac function in both preventive and therapeutic models, without causing left ventricular rupture or any adverse cardiac remodeling. In conclusion, early intervention in CF by ModRNA-CCN5 gene transfer is an efficient and safe therapeutic modality for treating MI-induced heart failure.

Myocardial infarction accelerates the progression of MASH by triggering immunoinflammatory response and induction of periosti

Patients with metabolic dysfunction-associated steatotic liver disease (MASLD), especially advanced metabolic dysfunction-associated steatohepatitis (MASH), have an increased risk of cardiovascular diseases (CVDs). Whether CVD events will, in turn, influence the pathogenesis of MASLD remains unknown. Here, we show that myocardial infarction (MI) accelerates hepatic pathological progression of MASLD. Patients with MASLD who experience CVD events after their diagnosis exhibit accelerated liver fibrosis progression. MI promotes hepatic fibrosis in mice with MASH, accompanied by elevated circulating Ly6Chi monocytes and their recruitment to damaged liver tissues. These adverse effects are significantly abrogated when deleting these cells. Meanwhile, MI substantially increases circulating and cardiac periostin levels, which act on hepatocytes and stellate cells to promote hepatic lipid accumulation and fibrosis, finally exacerbating hepatic pathological progression of MASH. These preclinical and clinical results demonstrate that MI alters systemic homeostasis and upregulates pro-fibrotic factor production, triggering cross-disease communication that accelerates hepatic pathological progression of MASLD.

Cardiac and perivascular myofibroblasts, matrifibrocytes, and immune fibrocytes in hypertension; commonalities and differences with other cardiovascular diseases

Hypertension is a major cause of cardiovascular diseases such as myocardial infarction and stroke. Cardiovascular fibrosis occurs with hypertension and contributes to vascular resistance, aortic stiffness, and cardiac hypertrophy. However, the molecular mechanisms leading to fibroblast activation in hypertension remain largely unknown. There are two types of fibrosis: replacement fibrosis and reactive fibrosis. Replacement fibrosis occurs in response to the loss of viable tissue to form a scar. Reactive fibrosis occurs in response to an increase in mechanical and neurohormonal stress. Although both types of fibrosis are considered adaptive processes, they become maladaptive when the tissue loss is too large, or the stress persists. Myofibroblasts represent a subpopulation of activated fibroblasts that have gained contractile function to promote wound healing. Therefore, myofibroblasts are a critical cell type that promotes replacement fibrosis. Although myofibroblasts were recognized as the fibroblasts participating in reactive fibrosis, recent experimental evidence indicated there are distinct fibroblast populations in cardiovascular reactive fibrosis. Accordingly, we will discuss the updated definition of fibroblast subpopulations, the regulatory mechanisms, and their potential roles in cardiovascular pathophysiology utilizing new knowledge from various lineage tracing and single-cell RNA sequencing studies. Among the fibroblast subpopulations, we will highlight the novel roles of matrifibrocytes and immune fibrocytes in cardiovascular fibrosis including experimental models of hypertension, pressure overload, myocardial infarction, atherosclerosis, aortic aneurysm, and nephrosclerosis. Exploration into the molecular mechanisms involved in the differentiation and activation of those fibroblast subpopulations may lead to novel treatments for end-organ damage associated with hypertension and other cardiovascular diseases.

Differential sex-dependent susceptibility to diastolic dysfunction and arrhythmia in cardiomyocytes from obese diabetic HFpEF model

AIM

Sex-differences in heart failure with preserved ejection fraction (HFpEF) are important, but key mechanisms involved are incompletely understood. While animal models can inform about sex-dependent cellular and molecular changes, many previous preclinical HFpEF models have failed to recapitulate sex-dependent characteristics of human HFpEF. We tested for sex-differences in HFpEF using a two-hit mouse model (leptin receptor-deficient db/db mice plus aldosterone infusion for 4 weeks; db/db+Aldo).

METHODS AND RESULTS

We performed echocardiography, electrophysiology, intracellular Ca2+ imaging, and protein analysis. Female HFpEF mice exhibited more severe diastolic dysfunction in line with increased titin N2B isoform expression and PEVK element phosphorylation, and reduced troponin-I phosphorylation. Female HFpEF mice had lower BNP levels than males despite similar comorbidity burden (obesity, diabetes) and cardiac hypertrophy in both sexes. Male HFpEF mice were more susceptible to cardiac alternans. Male HFpEF cardiomyocytes (versus female) exhibited higher diastolic [Ca2+], slower Ca2+ transient decay, reduced L-type Ca2+ current, more pronounced enhancement of the late Na+ current, and increased short-term variability of action potential duration (APD). However, male and female HFpEF myocytes showed similar downregulation of inward rectifier and transient outward K+ currents, APD prolongation, and frequency of delayed afterdepolarizations. Inhibition of Ca2+/calmodulin-dependent protein kinase II (CaMKII) reversed all pathological APD changes in HFpEF in both sexes, and empagliflozin pretreatment mimicked these effects of CaMKII inhibition. Vericiguat had only slight benefits, and these effects were larger in HFpEF females.

CONCLUSION

We conclude that the db/db+Aldo preclinical HFpEF murine model recapitulates key sex-specific mechanisms in HFpEF and provides mechanistic insights into impaired excitation-contraction coupling and sex-dependent differential arrhythmia susceptibility in HFpEF with potential therapeutic implications. In male HFpEF myocytes, altered Ca2+ handling and electrophysiology aligned with diastolic dysfunction and arrhythmias, while worse diastolic dysfunction in females may depend more on altered myofilaments properties.

The Senescent Heart-"Age Doth Wither Its Infinite Variety"

Cardiovascular diseases are a leading cause of morbidity and mortality world-wide. While many factors like smoking, hypertension, diabetes, dyslipidaemia, a sedentary lifestyle, and genetic factors can predispose to cardiovascular diseases, the natural process of aging is by itself a major determinant of the risk. Cardiac aging is marked by a conglomerate of cellular and molecular changes, exacerbated by age-driven decline in cardiac regeneration capacity. Although the phenotypes of cardiac aging are well characterised, the underlying molecular mechanisms are far less explored. Recent advances unequivocally link cardiovascular aging to the dysregulation of critical signalling pathways in cardiac fibroblasts, which compromises the critical role of these cells in maintaining the structural and functional integrity of the myocardium. Clearly, the identification of cardiac fibroblast-specific factors and mechanisms that regulate cardiac fibroblast function in the senescent myocardium is of immense importance. In this regard, recent studies show that Discoidin domain receptor 2 (DDR2), a collagen-activated receptor tyrosine kinase predominantly located in cardiac fibroblasts, has an obligate role in cardiac fibroblast function and cardiovascular fibrosis. Incisive studies on the molecular basis of cardiovascular aging and dysregulated fibroblast function in the senescent heart would pave the way for effective strategies to mitigate cardiovascular diseases in a rapidly growing elderly population.

Cardioprotective Effects of Hydrogen Sulfide and Its Potential Therapeutic Implications in the Amelioration of Duchenne Muscular Dystrophy Cardiomyopathy

Hydrogen sulfide (H2S) belongs to the family of gasotransmitters and can modulate a myriad of biological signaling pathways. Among others, its cardioprotective effects, through antioxidant, anti-inflammatory, anti-fibrotic, and proangiogenic activities, are well-documented in experimental studies. Cardiorespiratory failure, predominantly cardiomyopathy, is a life-threatening complication that is the number one cause of death in patients with Duchenne muscular dystrophy (DMD). Although recent data suggest the role of H2S in ameliorating muscle wasting in murine and Caenorhabditis elegans models of DMD, possible cardioprotective effects have not yet been addressed. In this review, we summarize the current understanding of the role of H2S in animal models of cardiac dysfunctions and cardiac cells. We highlight that DMD may be amenable to H2S supplementation, and we suggest H2S as a possible factor regulating DMD-associated cardiomyopathy.

Endothelial periostin regulates vascular remodeling by promoting endothelial dysfunction in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by vascular remodeling associated with extracellular matrix (ECM) deposition, vascular cell hyperproliferation, and neointima formation in the small pulmonary artery. Endothelial dysfunction is considered a key feature in the initiation of vascular remodeling. Although vasodilators have been used for the treatment of PAH, it remains a life-threatening disease. Therefore, it is necessary to identify novel therapeutic targets for PAH treatment. Periostin (POSTN) is a secretory ECM protein involved in physiological and pathological processes, such as tissue remodeling, cell adhesion, migration, and proliferation. Although POSTN has been proposed as a potential target for PAH treatment, its role in endothelial cells has not been fully elucidated. Here, we demonstrated that POSTN upregulation correlates with PAH by analyzing a public microarray conducted on the lung tissues of patients with PAH and biological experimental results from in vivo and in vitro models. Moreover, POSTN overexpression leads to ECM deposition and endothelial abnormalities such as migration. We found that PAH-associated endothelial dysfunction is mediated at least in part by the interaction between POSTN and integrin-linked protein kinase (ILK), followed by activation of nuclear factor-κB signaling. Silencing POSTN or ILK decreases PAH-related stimuli-induced ECM accumulation and attenuates endothelial abnormalities. In conclusion, our study suggests that POSTN serves as a critical regulator of PAH by regulating vascular remodeling, and targeting its role as a potential therapeutic strategy for PAH.

The role of periostin in cardiac fibrosis

Cardiac fibrosis, which is the buildup of proteins in the connective tissues of the heart, can lead to end-stage extracellular matrix (ECM) remodeling and ultimately heart failure. Cardiac remodeling involves changes in gene expression in cardiac cells and ECM, which significantly leads to the morbidity and mortality in heart failure. However, despite extensive research, the elusive intricacies underlying cardiac fibrosis remain unidentified. Periostin, an extracellular matrix (ECM) protein of the fasciclin superfamily, acts as a scaffold for building complex architectures in the ECM, which improves intermolecular interactions and augments the mechanical properties of connective tissues. Recent research has shown that periostin not only contributes to normal ECM homeostasis in a healthy heart but also serves as a potent inducible regulator of cellular reorganization in cardiac fibrosis. Here, we reviewed the constitutive domain of periostin and its interaction with other ECM proteins. We have also discussed the critical pathophysiological functions of periostin in cardiac remodeling mechanisms, including two distinct yet potentially intertwined mechanisms. Furthermore, we will focus on the intrinsic complexities within periostin research, particularly surrounding the contentious issues observed in experimental findings.

Fibroblasts under pressure: cardiac fibroblast responses to hypertension and antihypertensive therapies

Approximately 50% of Americans have hypertension, which significantly increases the risk of heart failure. In response to increased peripheral resistance in hypertension, intensified mechanical stretch in the myocardium induces cardiomyocyte hypertrophy and fibroblast activation to withstand increased pressure overload. This changes the structure and function of the heart, leading to pathological cardiac remodeling and eventual progression to heart failure. In the presence of hypertensive stimuli, cardiac fibroblasts activate and differentiate to myofibroblast phenotype capable of enhanced extracellular matrix secretion in coordination with other cell types, mainly cardiomyocytes. Both systemic and local renin-angiotensin-aldosterone system activation lead to increased angiotensin II stimulation of fibroblasts. Angiotensin II directly activates fibrotic signaling such as transforming growth factor β/SMAD and mitogen-activated protein kinase (MAPK) signaling to produce extracellular matrix comprised of collagens and matricellular proteins. With the advent of single-cell RNA sequencing techniques, heterogeneity in fibroblast populations has been identified in the left ventricle in models of hypertension and pressure overload. The various clusters of fibroblasts reveal a range of phenotypes and activation states. Select antihypertensive therapies have been shown to be effective in limiting fibrosis, with some having direct actions on cardiac fibroblasts. The present review focuses on the fibroblast-specific changes that occur in response to hypertension and pressure overload, the knowledge gained from single-cell analyses, and the effect of antihypertensive therapies. Understanding the dynamics of hypertensive fibroblast populations and their similarities and differences by sex is crucial for the advent of new targets and personalized medicine.

Heart Failure Promotes Cancer Progression in an Integrin β1-Dependent Manner

Heart failure and cancer are currently the deadliest diseases in the Western world, posing the most pressing clinical challenges that remain unmet today. Both conditions share similar risk factors, including age, genetics, lifestyle, chronic inflammation, stress, and more. Furthermore, medications that are being used to counteract cancer frequently result in cardiotoxicity and the spontaneous emergence of heart failure. Thus, heart failure and cancer display an intimate connection and share similarities. Recent studies show that cardiac remodeling and heart failure promote cancer progression and metastasis. Using three different mouse models for heart failure revealed that the communication between the remodeled heart and the tumor is facilitated through multiple secreted factors. Among these factors, Periostin was consistently found to be elevated in all models and was shown to be required in vitro. Yet, whether Periostin is necessary for tumor promotion in vivo is unknown. Towards this end, we examined tumor promotion in mice lacking Periostin following transverse aortic constriction (TAC). Despite the loss of Periostin, tumor growth was promoted in the TAC-operated mice. This likely occurred due to increased levels of various cytokines and growth factors in Periostin KO mice. Many of these factors are potential ligands of Integrin receptors. Therefore, we next studied the role of Integrin receptors in the tumor-promotion phenotype following heart failure. We generated cancer cells with an Integrin β1 loss of function mutation and examined tumor growth in the presence and absence of heart failure. Integrin β1 KO cancer cells fail to display cardiac-remodeling-dependent tumor-promotion. Interestingly, a previous study showed that renal cell carcinoma cells (Renca) fail to be promoted following a myocardial infarction. Consistently, we show that Renca cells do not respond to secreted factors derived from the failing heart both in vitro and in vivo. Interestingly, Renca cells display low basal mRNA levels of Integrin β1 which may explain the inability of heart failure to promote their growth. The findings may have significant clinical relevance to cardio-oncology patients who suffer from cancers with high levels of Integrin β1. Chemotherapy leading to cardiotoxicity in these patients may generate a vicious cycle with poor prognosis.

Protective effects of macrophage-specific integrin α5 in myocardial infarction are associated with accentuated angiogenesis

Macrophages sense changes in the extracellular matrix environment through the integrins and play a central role in regulation of the reparative response after myocardial infarction. Here we show that macrophage integrin α5 protects the infarcted heart from adverse remodeling and that the protective actions are associated with acquisition of an angiogenic macrophage phenotype. We demonstrate that myeloid cell- and macrophage-specific integrin α5 knockout mice have accentuated adverse post-infarction remodeling, accompanied by reduced angiogenesis in the infarct and border zone. Single cell RNA-sequencing identifies an angiogenic infarct macrophage population with high Itga5 expression. The angiogenic effects of integrin α5 in macrophages involve upregulation of Vascular Endothelial Growth Factor A. RNA-sequencing of the macrophage transcriptome in vivo and in vitro followed by bioinformatic analysis identifies several intracellular kinases as potential downstream targets of integrin α5. Neutralization assays demonstrate that the angiogenic actions of integrin α5-stimulated macrophages involve activation of Focal Adhesion Kinase and Phosphoinositide 3 Kinase cascades.

Periostin is overexpressed, correlated with fibrosis and differs among grades of cardiomyocyte hypertrophy in myectomy tissue of patients with hypertrophic cardiomyopathy

Periostin, a secreted matricellular protein, has been implicated in cardiac extracellular matrix remodeling and fibrosis. Evidence suggest that periostin stimulates cardiomyocyte hypertrophy. The current study aims to investigate the extent of periostin expression in patients with advanced Hypertrophic Cardiomyopathy (HCM) and its correlation with fibrosis and hallmark histopathological features of the disease. Interventricular septal tissue from thirty-nine HCM patients who underwent myectomy and five controls who died from non-cardiac causes was obtained. Staining with Masson's Trichrome and immunohistochemistry were used to localize fibrosis and periostin respectively. The extent of fibrosis and the expression of periostin were defined as the stained percentage of total tissue area using digital pathology software. Periostin expression was higher in HCM patients compared to controls (p<0.0001), positively correlated with the extent of fibrosis (r = 0.82, p<0.001), positively correlated with maximal interventricular septal thickness (Rho = 0.33, p = 0.04) and negatively correlated with LVEF (r = -0.416, p = 0.009). Periostin was approximately co-localized with fibrosis. Mean periostin expression was lower in patients with mild grade cardiomyocyte hypertrophy compared to those with moderate grade (p = 0.049) and lower in patients with mild grade replacement fibrosis compared to moderate grade (p = 0.036). In conclusion, periostin is overexpressed in advanced HCM, correlated with fibrosis and possibly related to cardiomyocyte hypertrophy.

Cardiomyocyte NOX4 regulates resident macrophage-mediated inflammation and diastolic dysfunction in stress cardiomyopathy

In acute sympathetic stress, catecholamine overload can lead to stress cardiomyopathy. We tested the hypothesis that cardiomyocyte NOX4 (NADPH oxidase 4)-dependent mitochondrial oxidative stress mediates inflammation and diastolic dysfunction in stress cardiomyopathy. Isoproterenol (ISO; 5 mg/kg) injection induced sympathetic stress in wild-type and cardiomyocyte (CM)-specific Nox4 knockout (Nox4CM-/-) mice. Wild-type mice treated with ISO showed higher CM NOX4 expression, H2O2 levels, inflammasome activation, and IL18, IL6, CCL2, and TNFα levels than Nox4CM-/- mice. Spectral flow cytometry and t-SNE analysis of cardiac cell suspensions showed significant increases in pro-inflammatory and pro-fibrotic embryonic-derived resident (CCR2-MHCIIhiCX3CR1hi) macrophages in wild-type mice 3 days after ISO treatment, whereas Nox4CM-/- mice had a higher proportion of embryonic-derived resident tissue-repair (CCR2-MHCIIloCX3CR1lo) macrophages. A significant increase in cardiac fibroblast activation and interstitial collagen deposition and a restrictive pattern of diastolic dysfunction with increased filling pressure was observed in wild-type hearts compared with Nox4CM-/- 7 days post-ISO. A selective NOX4 inhibitor, GKT137831, reduced myocardial mitochondrial ROS, macrophage infiltration, and fibrosis in ISO-injected wild-type mice, and preserved diastolic function. Our data suggest sympathetic overstimulation induces resident macrophage (CCR2-MHCII+) activation and myocardial inflammation, resulting in fibrosis and impaired diastolic function mediated by CM NOX4-dependent ROS.

Cardiac proteomic profiling suggests that hypertrophic and dilated cardiomyopathy share a common pathogenetic pathway of the calcium signalling pathway

OBJECTIVE

Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are classified as different diseases but have many similar pathogenic genes and clinical symptoms. Previous research has focused on mutated genes. This study was conducted to identify key molecular mechanisms and explore effective therapeutic targets.

METHODS

Myocardial tissue was harvested from patients with HCM (n = 3) or DCM (n = 4) during surgery. Hearts donated by healthy traffic accident victims were treated as controls (n = 4). Total proteins were extracted for liquid chromatography-tandem mass spectrometry. Differentially expressed proteins (DEPs) were annotated via GO and KEGG analyses. Selected distinguishing protein abundance was confirmed by western blotting.

RESULTS

Compared with the control group, there were 121 and 76 DEPs in the HCM and DCM groups, respectively. GO terms for these two comparisons are associated with contraction-related components and actin binding. Additionally, the most significantly upregulated and downregulated proteins were periostin and tropomyosin alpha-3 chain in both comparisons. Moreover, when comparing the HCM and DCM groups, we found 60 significant DEPs, and the GO and KEGG terms are related to the calcium signalling pathway. Expression of the calcium regulation-related protein peptidyl-prolyl cis-trans isomerase (FKBP1A) was significantly upregulated in multiple samples.

CONCLUSION

HCM and DCM have many mutual pathogenetic pathways. Calcium ion-related processes are among the most significant factors affecting disease development. For HCM and DCM, research on regulating linchpin protein expression or interfering with key calcium-related pathways may be more beneficial than genetic research.

Deficiency for scavenger receptors Stabilin-1 and Stabilin-2 leads to age-dependent renal and hepatic depositions of fasciclin domain proteins TGFBI and Periostin in mice

Stabilin-1 (Stab1) and Stabilin-2 (Stab2) are two major scavenger receptors of liver sinusoidal endothelial cells that mediate removal of diverse molecules from the plasma. Double-knockout mice (Stab-DKO) develop impaired kidney function and a decreased lifespan, while single Stabilin deficiency or therapeutic inhibition ameliorates atherosclerosis and Stab1-inhibition is subject of clinical trials in immuno-oncology. Although POSTN and TFGBI have recently been described as novel Stabilin ligands, the dynamics and functional implications of these ligands have not been comprehensively studied. Immunofluorescence, Western Blotting and Simple Western™ as well as in situ hybridization (RNAScope™) and qRT-PCR were used to analyze transcription levels and tissue distribution of POSTN and TGFBI in Stab-KO mice. Stab-POSTN-Triple deficient mice were generated to assess kidney and liver fibrosis and function in young and aged mice. TGFBI and POSTN protein accumulated in liver tissue in Stab-DKO mice and age-dependent in glomeruli of Stabilin-deficient mice despite unchanged transcriptional levels. Stab-POSTN-Triple KO mice showed glomerulofibrosis and a reduced lifespan comparable to Stab-DKO mice. However, alterations of the glomerular diameter and vascular density were partially normalized in Stab-POSTN-Triple KO. TGFBI and POSTN are Stabilin-ligands that are deposited in an age-dependent manner in the kidneys and liver due to insufficient scavenging in the liver. Functionally, POSTN might partially contribute to the observed renal phenotype in Stab-DKO mice. This study provides details on downstream effects how Stabilin dysfunction affects organ function on a molecular and functional level.

The Effect and Mechanism of POSTN and Its Alternative Splicing on the Apoptosis of Myocardial Cells in Acute Myocardial Infarction: A Study in Vitro

Our study aimed to investigate key molecular targets in the pathogenesis of AMI, and provide new strategy for the treatment. In this work, the myocardial ischemia and hypoxia model was constructed by using HL-1 mouse cardiomyocytes. The over-expressing POSTN wild-type, mutant and negative control lentiviruses (GV492-POSTNWT,GV492-POSTN-MUT, GV492-NC) was conducted and transfected. Cardiomyocytes were examined for cell proliferation and apoptosis to explore the effects of POSTN and its alternative splicing. The endoplasmic reticulum stess-related apoptosis proteins were selected and detected. We found that POSTN could promote the proliferation of normal and hypoxic cardiomyocytes and inhibit their apoptosis. The mechanism by which POSTN inhibited cardiomyocyte apoptosis may be through inhibiting the GRP78-eIF2α-ATF4-CHOP pathway of endoplasmic reticulum stress. Alternative splicing of POSTN could inhibit the apoptosis of ischemic and hypoxic cardiomyocytes, and its mechanism needs to be confirmed by further studies. We drawed the conclusion that POSTN might be a potential therapeutic target for AMI.

Col1a2-Deleted Mice Have Defective Type I Collagen and Secondary Reactive Cardiac Fibrosis with Altered Hypertrophic Dynamics

RATIONALE

The adult cardiac extracellular matrix (ECM) is largely comprised of type I collagen. In addition to serving as the primary structural support component of the cardiac ECM, type I collagen also provides an organizational platform for other ECM proteins, matricellular proteins, and signaling components that impact cellular stress sensing in vivo.

OBJECTIVE

Here we investigated how the content and integrity of type I collagen affect cardiac structure function and response to injury.

METHODS AND RESULTS

We generated and characterized Col1a2-/- mice using standard gene targeting. Col1a2-/- mice were viable, although by young adulthood their hearts showed alterations in ECM mechanical properties, as well as an unanticipated activation of cardiac fibroblasts and induction of a progressive fibrotic response. This included augmented TGFβ activity, increases in fibroblast number, and progressive cardiac hypertrophy, with reduced functional performance by 9 months of age. Col1a2-loxP-targeted mice were also generated and crossed with the tamoxifen-inducible Postn-MerCreMer mice to delete the Col1a2 gene in myofibroblasts with pressure overload injury. Interestingly, while germline Col1a2-/- mice showed gradual pathologic hypertrophy and fibrosis with aging, the acute deletion of Col1a2 from activated adult myofibroblasts showed a loss of total collagen deposition with acute cardiac injury and an acute reduction in pressure overload-induce cardiac hypertrophy. However, this reduction in hypertrophy due to myofibroblast-specific Col1a2 deletion was lost after 2 and 6 weeks of pressure overload, as fibrotic deposition accumulated.

CONCLUSIONS

Defective type I collagen in the heart alters the structural integrity of the ECM and leads to cardiomyopathy in adulthood, with fibroblast expansion, activation, and alternate fibrotic ECM deposition. However, acute inhibition of type I collagen production can have an anti-fibrotic and anti-hypertrophic effect.

Periostin-An inducer of pro-fibrotic phenotype in monocytes and monocyte-derived macrophages in systemic sclerosis

Enhanced circulating blood periostin levels positively correlate with disease severity in　patients with systemic sclerosis (SSc). Monocytes/macrophages are predominantly associated with the pathogenesis of SSc, but the effect of periostin on immune cells, particularly monocytes and macrophages, still remains to be elucidated. We examined the effect of periostin on monocytes and monocyte-derived macrophages (MDM) in the pathogenesis of SSc. The modified Rodnan total skin thickness score in patients with dcSSc was positively correlated with the proportion of CD80-CD206+ M2 cells. The proportion of M2 macrophages was significantly reduced in rPn-stimulated MDMs of HCs compared to that of SSc patients. The mRNA expression of pro-fibrotic cytokines, chemokines, and ECM proteins was significantly upregulated in rPn-stimulated monocytes and MDMs as compared to that of control monocytes and MDMs. A similar trend was observed for protein expression in the respective MDMs. In addition, the ratio of migrated cells was significantly higher in rPn-stimulated as compared to control monocytes. These results suggest that periostin promotes inflammation and fibrosis in the pathogenesis of SSc by possible modulation of monocytes/macrophages.

More than just a small left ventricle: the right ventricular fibroblast and ECM in health and disease

Fibroblasts intricately organize and regulate the extracellular matrix (ECM) in cardiac health and disease. Excess deposition of ECM proteins causes fibrosis, resulting in disrupted signaling conduction and contributing to the development of arrhythmias and impaired cardiac function. Fibrosis is causally involved in cardiac failure in the left ventricle (LV). Fibrosis likely occurs in right ventricle (RV) failure, yet mechanisms remain unclear. Indeed, RV fibrosis is poorly understood with mechanisms often extrapolated from the LV to the RV. However, emerging data suggest that the LV and RV are distinct cardiac chambers and differ in regulation of the ECM and response to fibrotic stimuli. In the present review, we will discuss differences in ECM regulation in the healthy RV and LV. We will discuss the importance of fibrosis in the development of RV disease in pressure overload, inflammation, and aging. During this discussion, we will highlight mechanisms of fibrosis with respect to the synthesis of ECM proteins while acknowledging the importance of considering collagen breakdown. We will also discuss current knowledge of antifibrotic therapies in the RV and the need for additional research to help delineate the shared and distinct mechanisms of RV and LV fibrosis.

Modeling Cardiotoxicity in Pediatric Oncology Patients Using Patient-Specific iPSC-Derived Cardiomyocytes Reveals Downregulation of Cardioprotective microRNAs

Anthracyclines are widely used in the treatment of many solid cancers, but their efficacy is limited by cardiotoxicity. As the number of pediatric cancer survivors continues to rise, there has been a concomitant increase in people living with anthracycline-induced cardiotoxicity. Accordingly, there is an ongoing need for new models to better understand the pathophysiological mechanisms of anthracycline-induced cardiac damage. Here we generated induced pluripotent stem cells (iPSCs) from two pediatric oncology patients with acute cardiotoxicity induced by anthracyclines and differentiated them to ventricular cardiomyocytes (hiPSC-CMs). Comparative analysis of these cells (CTX hiPSC-CMs) and control hiPSC-CMs revealed that the former were significantly more sensitive to cell injury and death from the anthracycline doxorubicin (DOX), as measured by viability analysis, cleaved caspase 3 expression, oxidative stress, genomic and mitochondrial damage and sarcomeric disorganization. The expression of several mRNAs involved in structural integrity and inflammatory response were also differentially affected by DOX. Functionally, optical mapping analysis revealed higher arrythmia complexity after DOX treatment in CTX iPSC-CMs. Finally, using a panel of previously identified microRNAs associated with cardioprotection, we identified lower levels of miR-22-3p, miR-30b-5p, miR-90b-3p and miR-4732-3p in CTX iPSC-CMs under basal conditions. Our study provides valuable phenotype information for cellular models of cardiotoxicity and highlights the significance of using patient-derived cardiomyocytes for studying the associated pathogenic mechanisms.

Periostin in Osteoporosis and Cardiovascular Disease

Context

Osteoporosis (OP) and cardiovascular disease (CVD), prevalent disorders worldwide, often coexist and share common risk factors. The identification of common biomarkers could significantly improve patients' preventive care.

Objectives

The objectives are 1, to review periostin (Postn) involvement in osteoporosis and in CVD, and 2, identify if Postn could be a common biomarker.

Design

This is a scoping review on Postn in OP and CVD.

Methods

Databases were searched, in vitro and in vivo, for publications in English on Postn, bone, and the cardiovascular system, with no limit regarding publication date.

Results

Postn appears as a key factor in OP and CVD. Its role as a potential biomarker in both pathologies is described in recent studies, but a number of limitations have been identified.

Conclusions

Current evidence provides fragmented views on Postn in OP and CVD and does not encapsulate Postn as a common pivotal thread linking these comorbidities. A number of gaps impede highlighting Postn as a common biomarker. There is room for future basic and clinical research with Postn as a marker and a target to provide new therapeutic options for aging patients with concomitant OP and CVD.

Royal jelly mediates fibrotic signaling, collagen cross-linking and cell proliferation in cardiac fibroblasts

Royal jelly (RJ) is a multifunctional bee product with a unique composition and wide-ranging biological properties, including antioxidant, anti-inflammatory and antiproliferative activities. Still, little is known about the possible myocardial protective properties of RJ. Considering that sonication could enhance RJ bioactivity, this study aimed to assess the effects of non-sonicated (NS) and sonicated (S) RJ on fibrotic signaling, cell proliferation, and collagen production in cardiac fibroblasts. S-RJ was produced by ultrasonication at 20 kHz. Ventricular fibroblasts isolated from neonatal rats were cultured and treated with different concentrations of NS-RJ or S-RJ (0, 50, 100, 150, 200, and 250 µg/well). S-RJ significantly depressed the expression levels of transglutaminase 2 (TG2) mRNA across all the concentrations tested and was inversely associated with the expression of this profibrotic marker. S-RJ and NS-RJ displayed distinct dose-dependent effects on mRNA expression of several other profibrotic, proliferation, and apoptotic markers. Unlike NS-RJ, S-RJ elicited strong negative dose-dependent relationships with the expression of profibrotic markers (TG2, COL1A1, COL3A1, FN1, CTGF, MMP-2, α-SMA, TGF-β1, CX43, periostin), as well as proliferation (CCND1) and apoptotic (BAX, BAX/BCL-2) markers, indicating that RJ dose-response effects were significantly modified by sonification. NS-RJ and S-RJ increased the content of soluble collagen, while decreasing collagen cross-linking. Collectively, these findings show that S-RJ has a greater range of action than NS-RJ for downregulating the expression of biomarkers associated with cardiac fibrosis. Reduced biomarker expression and collagen cross-linkages upon cardiac fibroblast treatment with specific concentrations of S-RJ or NS-RJ suggests putative roles and mechanisms by which RJ may confer some protection against cardiac fibrosis.

Single-nucleus ribonucleic acid-sequencing and spatial transcriptomics reveal the cardioprotection of Shexiang Baoxin Pill (SBP) in mice with myocardial ischemia-reperfusion injury

Aim: The Shexiang Baoxin Pill (SBP) has been extensively used to treat cardiovascular diseases in China for four decades, and its clinical efficacy has been widely approved. However, the mechanism by which this is achieved remains largely unexplored. Research attempting to understand the underlying mechanism is ongoing, but the findings are controversial. Here, we aimed to explore the possible mechanism of SBP in myocardial ischemia-reperfusion (I/R) injury using heart single-nucleus and spatial ribonucleic acid (RNA) sequencing. Methods: We established a murine myocardial I/R injury model in C57BL/6 mice by ligating and recanalizing the left coronary artery anterior descending branch. Subsequently, single-nucleus RNA-seq and spatial transcriptomics were performed on mice cardiac tissue. We initially assessed the status of cell types and subsets in the model administered with or without SBP. Results: We used single-nucleus RNA sequencing to comprehensively analyze cell types in the cardiac tissue of sham, I/R, and SBP mice. Nine samples from nine individuals were analyzed, and 75,546 cells were obtained. We classified the cells into 28 clusters based on their expression characteristics and annotated them into seven cell types: cardiomyocytes, endothelial cells, fibroblasts, myeloid cells, smooth muscle cells, B cells, and T cells. The SBP group had distinct cellular compositions and features than the I/R group. Furthermore, SBP-induced cardioprotection against I/R was associated with enhanced cardiac contractility, reduced endocardial cell injury, increased endocardial-mediated angiogenesis, and inhibited fibroblast proliferation. In addition, macrophages had active properties. Conclusion: SBP improves the early LVEF of I/R mice and has a cardioprotective effect. Through sequencing analysis, we observed that SBP can increase the gene expression of Nppb and Npr3 in the infarct area of the heart. Npr3 is related to vascular generation mediated by endocardial cells and requires further research. In addition, SBP increases the number of fibroblasts, inhibits the expression of genes related to fibroblast activation and proliferation, and increases the transformation of endothelial cells into fibroblasts. These findings will help to indicate directions for further research.

Periosteal Bone Formation Varies with Age in Periostin Null Mice

Periostin, also known as osteoblast-specific factor 2, is a matricellular protein predominantly expressed at the periosteum of bone. During growth and development, periostin contributes to periosteal expansion by facilitating osteoblast differentiation and mineralization. Later in life, periosteal expansion provides an adaptive strategy to increase tissue strength without requiring substantial increase in bone mass. However, the function of periostin past skeletal maturity and during advanced aging is relatively unknown. The objective of this study was to examine the function of periostin in maintaining bone mass and tissue strength across different ages. In periostin null mice (Postn-/-), periosteal bone formation was significantly reduced in young (3 months) and adult mice (9 months). The lack of bone formation resulted in reduced bone mass and ultimate strength. Conversely, periosteal bone formation increased at advanced ages in 18-month-old Postn-/- mice. The increase in periosteal mineralization at advanced ages coincides with increased expression of vitronectin and osteopontin. Periosteal progenitors from Postn-/- mice displayed an increased capacity to mineralize when cultured on vitronectin, but not type-1 collagen. Altogether, these findings demonstrate the unique role of periostin in regulating periosteal bone formation at different ages and the potential for vitronectin to compensate in the absence of periostin.

Tissue and Serum Biomarkers in Degenerative Aortic Stenosis-Insights into Pathogenesis, Prevention and Therapy

Background and Aim. Degenerative Aortic Stenosis (DAS) is a common disease that causes substantial morbidity and mortality worldwide, especially in the older population. Our aim was to further investigate novel serum and tissue biomarkers to elucidate biological processes involved in this entity. Material and Methods. We evaluated the expression of six biomarkers significantly involved in cardiovascular pathology, i.e., irisin, periostin, osteoglycin, interleukin 18, high mobility group box 1 and proprotein convertase subtilisin/kexin type 9 in the serum at the protein level, and in the tissue at both the protein and mRNA levels of patients with AS (N = 60). Five normal valves obtained after transplantation from hearts of patients with idiopathic dilated cardiomyopathy were also studied. Serum measurements were also performed in 22 individuals without valvular disease who served as controls (C). Results. Higher levels of all factors were found in DAS patients’ serum than in normal C. IHC and PCR mRNA tissue analysis showed the presence of all biomarkers in the aortic valve cusps with DAS, but no trace of PCR mRNA was found in the five transplantation valves. Moreover, periostin serum levels correlated significantly with IHC and mRNA tissue levels in AS patients. Conclusion. We showed that six widely prevalent biomarkers affecting the atherosclerotic process were also involved in DAS, suggesting a strong osteogenic and pro-inflammatory profile, indicating that aortic valve calcification is a multifactorial biological process.

Cardiac Myocyte-Specific Overexpression of FASTKD1 Prevents Ventricular Rupture After Myocardial Infarction

Background The mitochondrial mRNA-binding protein FASTKD1 (Fas-activated serine/threonine [FAST] kinase domain-containing protein 1) protects myocytes from oxidative stress in vitro. However, the role of FASTKD1 in the myocardium in vivo is unknown. Therefore, we developed cardiac-specific FASTKD1 transgenic mice to test the effects of this protein on experimental myocardial infarction (MI). Methods and Results Transgenic mouse lines with cardiac myocyte-specific overexpression of FASTKD1 to varying degrees were generated. These mice displayed normal cardiac morphological features and function at the gross and microscopic levels. Isolated cardiac mitochondria from all transgenic mouse lines showed normal mitochondrial function, ATP levels, and permeability transition pore activity. Male nontransgenic and transgenic mice from the highest-expressing line were subjected to 8 weeks of permanent coronary ligation. Of nontransgenic mice, 40% underwent left ventricular free wall rupture within 7 days of MI compared with 0% of FASTKD1-overexpressing mice. At 3 days after MI, FASTKD1 overexpression did not alter infarct size. However, increased FASTKD1 resulted in decreased neutrophil and increased macrophage infiltration, elevated levels of the extracellular matrix component periostin, and enhanced antioxidant capacity compared with control mice. In contrast, markers of mitochondrial fusion/fission and apoptosis remained unaltered. Instead, transcriptomic analyses indicated activation of the integrated stress response in the FASTKD1 transgenic hearts. Conclusions Cardiac-specific overexpression of FASTKD1 results in viable mice displaying normal cardiac morphological features and function. However, these mice are resistant to MI-induced cardiac rupture and display altered inflammatory, extracellular matrix, and antioxidant responses following MI. Moreover, these protective effects were associated with enhanced activation of the integrated stress response.

Defining the timeline of periostin upregulation in cardiac fibrosis following acute myocardial infarction in mice

After myocardial infarction (MI), the heart's reparative response to the ischemic insult and the related loss of cardiomyocytes involves cardiac fibrosis, in which the damaged tissue is replaced with a fibrous scar. Although the scar is essential to prevent ventricular wall rupture in the infarction zone, it expands over time to remote, non-infarct areas, significantly increasing the extent of fibrosis and markedly altering cardiac structure. Cardiac function in this scenario deteriorates, thereby increasing the probability of heart failure and the risk of death. Recent works have suggested that the matricellular protein periostin, known to be involved in fibrosis, is a candidate therapeutic target for the regulation of MI-induced fibrosis and remodeling. Different strategies for the genetic manipulation of periostin have been proposed previously, yet those works did not properly address the time dependency between periostin activity and cardiac fibrosis. Our study aimed to fill that gap in knowledge and fully elucidate the explicit timing of cellular periostin upregulation in the infarcted heart to enable the safer and more effective post-MI targeting of periostin-producing cells. Surgical MI was performed in C57BL/6J and BALB/c mice by ligation of the left anterior descending coronary artery. Flow cytometry analyses of cells derived from the infarcted hearts and quantitative real-time PCR of the total cellular RNA revealed that periostin expression increased during days 2-7 and peaked on day 7 post-infarct, regardless of mouse strain. The established timeline for cellular periostin expression in the post-MI heart is a significant milestone toward the development of optimal periostin-targeted gene therapy.

Periostin as a Biomarker in the Setting of Glomerular Diseases-A Review of the Current Literature

Chronic kidney disease (CKD) is a highly prevalent and potential progressive condition with life-threatening consequences. Glomerular diseases (glomerulopathies) are causes of CKD that are potentially amenable by specific therapies. Significant resources have been invested in the identification of novel biomarkers of CKD progression and new targets for treatment. By using experimental models of kidney diseases, periostin has been identified amongst the most represented matricellular proteins that are commonly involved in the inflammation and fibrosis that characterize progressive kidney diseases. Periostin is highly expressed during organogenesis, with scarce expression in mature healthy tissues, but it is upregulated in multiple disease settings characterized by tissue injury and remodeling. Periostin was the most highly expressed matriceal protein in both animal models and in patients with glomerulopathies. Given that periostin is readily secreted from injury sites, and the variations in its humoral levels compared to the normal state were easily detectable, its potential role as a biomarker is suggested. Moreover, periostin expression was correlated with the degree of histological damage and with kidney function decline in patients with CKD secondary to both inflammatory (IgA nephropathy) and non-inflammatory (membranous nephropathy) glomerulopathies, while also displaying variability secondary to treatment response. The scope of this review is to summarize the existing evidence that supports the role of periostin as a novel biomarker in glomerulopathies.

Scleraxis and fibrosis in the pressure-overloaded heart

AIMS

In response to pro-fibrotic signals, scleraxis regulates cardiac fibroblast activation in vitro via transcriptional control of key fibrosis genes such as collagen and fibronectin; however, its role in vivo is unknown. The present study assessed the impact of scleraxis loss on fibroblast activation, cardiac fibrosis, and dysfunction in pressure overload-induced heart failure.

METHODS AND RESULTS

Scleraxis expression was upregulated in the hearts of non-ischemic dilated cardiomyopathy patients, and in mice subjected to pressure overload by transverse aortic constriction (TAC). Tamoxifen-inducible fibroblast-specific scleraxis knockout (Scx-fKO) completely attenuated cardiac fibrosis, and significantly improved cardiac systolic function and ventricular remodelling, following TAC compared to Scx+/+ TAC mice, concomitant with attenuation of fibroblast activation. Scleraxis deletion, after the establishment of cardiac fibrosis, attenuated the further functional decline observed in Scx+/+ mice, with a reduction in cardiac myofibroblasts. Notably, scleraxis knockout reduced pressure overload-induced mortality from 33% to zero, without affecting the degree of cardiac hypertrophy. Scleraxis directly regulated transcription of the myofibroblast marker periostin, and cardiac fibroblasts lacking scleraxis failed to upregulate periostin synthesis and secretion in response to pro-fibrotic transforming growth factor β.

CONCLUSION

Scleraxis governs fibroblast activation in pressure overload-induced heart failure, and scleraxis knockout attenuated fibrosis and improved cardiac function and survival. These findings identify scleraxis as a viable target for the development of novel anti-fibrotic treatments.

Phospholipase Cε insufficiency causes ascending aortic aneurysm and dissection

Phospholipase Cε (PLCε) is a phospholipase C isoform with a wide range of physiological functions. It has been implicated in aortic valve disorders, but its role in frequently associated aortic disease remains unclear. To determine the role of PLCε in thoracic aortic aneurysm and dissection (TAAD) we used PLCε-deficient mice, which develop aortic valve insufficiency and exhibit aortic dilation of the ascending thoracic aorta and arch without histopathological evidence of injury. Fourteen days of infusion of Plce1+/+ and Plce1-/- mice with angiotensin II (ANG II), which induces aortic dilation and dissection, led to sudden death secondary to ascending aortic dissection in 43% of Plce1-/- versus 5% of Plce1+/+ mice (P < 0.05). Medial degeneration and TAAD were detected in 80% of Plce1-/- compared with 10% of Plce1+/+ mice (P < 0.05) after 4 days of ANG II. Treatment with ANG II markedly increased PLCε expression within the ascending aortic adventitia. Total RNA sequencing demonstrated marked upregulation of inflammatory and fibrotic pathways mediated by interleukin-1β, interleukin-6, and tumor necrosis factor-α. In silico analysis of whole exome sequences of 258 patients with type A dissection identified 5 patients with nonsynonymous PLCE1 variants. Our data suggest that PLCε deficiency plays a role in the development of TAAD and aortic insufficiency.NEW & NOTEWORTHY We describe a novel phenotype by which PLCε deficiency predisposes to aortic valve insufficiency and ascending aortic aneurysm, dissection, and sudden death in the setting of ANG II-mediated hypertension. We demonstrate PLCE1 variants in patients with type A aortic dissection and aortic insufficiency, suggesting that PLCE1 may also play a role in human aortic disease. This finding is of very high significance because it has not been previously demonstrated that PLCε directly mediates aortic dissection.

Candidate genes and their alternative splicing may be potential biomarkers of acute myocardial infarction: a study of mouse model

Background

Acute myocardial infarction (AMI) is one of the leading causes of death in human being, and an effective diagnostic biomarker is still lacking. Whilst some gene association with AMI has been identified by RNA sequencing (RNA-seq), the relationship between alternative splicing and AMI is not clear.

Methods

We retrieved myocardial tissues within 24 h from mice with induced AMI and sham, and analysed the differentially expressed genes (DEGs) and differential alternative splicing genes (DASGs) by RNA-seq. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and protein interaction network analysis were performed on DEGs-DASGs-overlap genes. PCR was used to verify the expression levels of representative genes and alternative splicing in myocardial tissues of AMI and sham mice.

Results

1367 DEGs were identified, including 242 up-regulated and 1125 down-regulated genes, among which there were 42 DASGs. GO analysis showed that the cellular component was primarily enriched in plasma membrane, cell membrane integrity and extracellular region. The molecular function was enriched in protein binding and metal ion binding. The biological process was primarily enriched in cell adhesion, immune system process and cell differentiation. KEGG analysis showed the enrichment was mainly in JAK-STAT and PI3K-AKT signalling pathway. Postn, Fhl1, and Fn1 were low-expressed while Postn alternative splicing was high-expressed in myocardial tissue of AMI mice, which was consistent with sequencing results.

Conclusions

The pathogenesis of AMI involves differentially expressed genes and differential alternative splicing. These differentially expressed genes and their alternative splicing, especially, Fhl1, Fn1 and Postn may become new biomarkers of AMI.

Periostin overexpression in scleroderma cardiac tissue and its utility as a marker for disease complications

OBJECTIVE

To evaluate the levels of periostin in patients with systemic sclerosis (SSc) and their association with features of systemic sclerosis.

METHODS

The levels of periostin were assessed in the serum of 106 SSc patients and 22 healthy controls and by immunofluorescence staining in cardiac tissue from 4 SSc patients and 4 controls. Serum periostin was measured via enzyme-linked immunosorbent assay. The results were analyzed using Mann-Whitney test or Kruskal-Wallis test followed by Dunn's multiple comparisons tests and Spearman's test for correlations. Cardiac tissue from SSc patients and controls was stained for periostin and co-stained for periostin and collagen type I using immunofluorescence.

RESULTS

Periostin levels were higher in patients with SSc compared to controls and directly correlated to modified Rodnan skin score and echocardiography parameters of left ventricular measurements. Immunofluorescence staining in SSc cardiac tissue showed patchy periostin expression in all SSc patients, but not in controls. Furthermore, there was extensive periostin expression even in areas without collagen deposition, while all established fibrotic areas showed colocalization of collagen and periostin. There was no association between periostin levels and interstitial lung disease, pulmonary hypertension or other vascular complications.

CONCLUSION

Periostin is elevated in SSc cardiac tissue in vivo and circulating levels of periostin are increased in SSc, correlating with the extent of disease duration, degree of skin fibrosis, and left ventricular structural assessments. Periostin may be a potential biomarker that can provide further pathogenic insight into cardiac fibrosis in SSc.

Single-cell and spatial transcriptomics of the infarcted heart define the dynamic onset of the border zone in response to mechanical destabilization

The border zone (BZ) of the infarcted heart is a geographically complex and biologically enigmatic interface separating poorly perfused infarct zones (IZs) from remote zones (RZs). The cellular and molecular mechanisms of myocardial BZs are not well understood because microdissection inevitably combines them with uncontrolled amounts of RZs and IZs. Here, we use single-cell/nucleus RNA sequencing, spatial transcriptomics and multiplexed RNA fluorescence in situ hybridization to redefine the BZ based on cardiomyocyte transcriptomes. BZ1 (Nppa + Xirp2 -) forms a hundreds-of-micrometer-thick layer of morphologically intact cells adjacent to RZs that are detectable within an hour of injury. Meanwhile, BZ2 (Nppa + Xirp2 +) forms a near-single-cell-thick layer of morphologically distorted cardiomyocytes at the IZ edge that colocalize with matricellular protein-expressing myofibroblasts and express predominantly mechanotransduction genes. Surprisingly, mechanical injury alone is sufficient to induce BZ genes. We propose a 'loss of neighbor' hypothesis to explain how ischemic cell death mechanically destabilizes the BZ to induce its transcriptional response.

Integrins in cardiac fibrosis

Cells sense mechanical stress and changes in their matrix environment through the integrins, a family of heterodimeric surface receptors that bind to extracellular matrix ligands and trigger cytoskeletal remodeling, while transducing a wide range of intracellular signals. Integrins have been extensively implicated in regulation of inflammation, repair and fibrosis in many different tissues. This review manuscript discusses the role of integrin-mediated cascades in myocardial fibrosis. In vitro studies have demonstrated that β1 and αv integrins play an important role in fibrogenic conversion of cardiac fibroblast, acting through direct stimulation of FAK/Src cascades, or via accentuation of growth factor signaling. Fibrogenic actions of αv integrins may be mediated, at least in part, through pericellular activation of latent TGF-β stores. In vivo evidence supporting the role of integrin heterodimers in fibrotic cardiac remodeling is limited to associative evidence, and to experiments using pharmacologic inhibitors, or global loss-of-function approaches. Studies documenting in vivo actions of integrins on fibroblasts using cell-specific strategies are lacking. Integrin effects on leukocytes may also contribute to the pathogenesis of fibrotic myocardial responses by mediating recruitment and activation of fibrogenic macrophages. The profile and role of integrins in cardiac fibrosis may be dependent on the underlying pathologic condition. Considering their cell surface localization and the availability of small molecule inhibitors, integrins may be attractive therapeutic targets for patients with heart failure associated with prominent fibrotic remodeling.

Periostin contributes to the adventitial remodeling of atherosclerosis by activating adventitial fibroblasts

Background and aims

Adventitial remodeling is an important pathological process of atherosclerosis, but cues implicated in adventitial remodeling are far from fully understood. Periostin (POSTN), a matricellular protein, has been demonstrated to have multiple roles in cardiovascular diseases. The aim of the study was to explore the function of POSTN in adventitial remodeling during atherosclerosis.

Methods

An atherosclerosis model was constructed based on ApoE-/- mice fed a high-fat and high-cholesterol diet. The expression of POSTN in the adventitia of mouse atherosclerotic vascular specimens was detected by immunohistochemical staining. The roles of POSTN in regulating adventitial fibroblast activation were assessed by cell contractility and activation marker α-smooth muscle actin (α-SMA) expression evaluation in adventitial fibroblasts overexpressing POSTN. In addition, we performed quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting to examine the expression of the proinflammatory chemokines transforming growth factor-β1 (TGF-β1) and monocyte chemotactic protein 1 (MCP1), as well as some extracellular matrix (ECM)-related proteins, in POSTN-overexpressing adventitial fibroblasts. Finally, the integrin-related signaling pathway was detected upon POSTN overexpression in adventitial fibroblasts.

Results

POSTN was highly expressed in the adventitia of atherosclerotic aortae in the mouse atherosclerosis model and promoted the activation and contraction of adventitial fibroblasts. Meanwhile, POSTN also induced adventitial fibroblasts to express TGF-β1, monocyte chemotactic protein-1 (MCP1), and ECM-related proteins and activated the phosphorylation of focal adhesion kinase (FAK) and Src.

Conclusions

Our results revealed that POSTN is elevated in adventitia during atherosclerosis and contributes to the adventitial remodeling of atherosclerosis by activating adventitial fibroblasts.

Periostin: biology and function in cancer

Periostin (POSTN), a member of the matricellular protein family, is a secreted adhesion-related protein produced in the periosteum and periodontal ligaments. Matricellular proteins are a nonstructural family of extracellular matrix (ECM) proteins that regulate a wide range of biological processes in both normal and pathological conditions. Recent studies have demonstrated the key roles of these ECM proteins in the tumor microenvironment. Furthermore, periostin is an essential regulator of bone and tooth formation and maintenance, as well as cardiac development. Also, periostin interacts with multiple cell-surface receptors, especially integrins, and triggers signals that promote tumor growth. According to recent studies, these signals are implicated in cancer cell survival, epithelial-mesenchymal transition (EMT), invasion, and metastasis. In this review, we will summarize the most current data regarding periostin, its structure and isoforms, expressions, functions, and regulation in normal and cancerous tissues. Emphasis is placed on its association with cancer progression, and also future potential for periostin-targeted therapeutic approaches will be explored.

Galunisertib-Loaded Gelatin Methacryloyl Hydrogel Microneedle Patch for Cardiac Repair after Myocardial Infarction

Uncontrolled and excessive fibrosis after myocardial infarction (MI) in the peri-infarct zone leads to left ventricular remodeling and deterioration of cardiac function. Inhibiting fibroblast activation during the mature phase of cardiac repair improves cardiac remodeling and function after MI. Here, we engineered a biocompatible microneedle (MN) patch using gelatin methacryloyl and loaded it with galunisertib, a transforming growth factor-beta (TGF-β)-specific inhibitor, to treat excessive cardiac fibrosis after MI. The MN patch could sustainably release galunisertib for more than 2 weeks and provide mechanical support for the fragile ventricular wall. After being applied to a rat model of MI, the galunisertib-loaded MN patch improved long-term cardiac function and reduced cardiac fibrosis by effectively inhibiting TGF-β depending on fibroblast activation. This strategy shows the potential of the MN patch as an advanced platform to locally deliver direct antifibrotic drugs to prevent myocardial fibrosis for the treatment of MI and the promotion of cardiac repair.

Emerging roles of the RNA modifications N6-methyladenosine and adenosine-to-inosine in cardiovascular diseases

Cardiovascular diseases lead the mortality and morbidity disease metrics worldwide. A multitude of chemical base modifications in ribonucleic acids (RNAs) have been linked with key events of cardiovascular diseases and metabolic disorders. Named either RNA epigenetics or epitranscriptomics, the post-transcriptional RNA modifications, their regulatory pathways, components, and downstream effects substantially contribute to the ways our genetic code is interpreted. Here we review the accumulated discoveries to date regarding the roles of the two most common epitranscriptomic modifications, N6-methyl-adenosine (m6A) and adenosine-to-inosine (A-to-I) editing, in cardiovascular disease.

Neurogranin regulates calcium-dependent cardiac hypertrophy

Intracellular Ca2+-calmodulin (CaM) signaling plays an important role in Ca2+-CaM-dependent kinase (CaMKII) and calcineurin (CaN)-mediated cardiac biology. While neurogranin (Ng) is known as a major Ca2+-CaM modulator in the brain, its pathophysiological role in cardiac hypertrophy has never been studied before. In the present study, we report that Ng is expressed in the heart and depletion of Ng dysregulates Ca2+ homeostasis and promotes cardiac failure in mice. 10-month-old Ng null mice demonstrate significantly increased heart-to-body weight ratios compared to wild-type. Using histological approaches, we identified that depletion of Ng increases cardiac hypertrophy, fibrosis, and collagen deposition near perivascular areas in the heart tissue of Ng null mice. Ca2+ spark experiments revealed that cardiac myocytes isolated from Ng null mice have decreased spark frequency and width, while the duration of sparks is significantly increased. We also identified that a lack of Ng increases CaMKIIδ signaling and periostin protein expression in these mouse hearts. Overall, we are the first study to explore how Ng expression in the heart plays an important role in Ca2+ homeostasis in cardiac myocytes as well as the pathophysiology of cardiac hypertrophy and fibrosis.

Periostin-related progression of different types of experimental pulmonary hypertension: A role for M2 macrophage and FGF-2 signalling

BACKGROUND AND OBJECTIVE

Remodelling of pulmonary arteries (PA) contributes to the progression of pulmonary hypertension (PH). Periostin, a matricellular protein, has been reported to be involved in the development of PH. We examined the role of periostin in the pathogenesis of PH using different types of experimental PH.

METHODS

PH was induced by vascular endothelial growth factor receptor antagonist (Sugen5416) plus hypoxic exposure (SuHx) and venous injection of monocrotaline-pyrrole (MCT-P) in wild-type (WT) and periostin-/- mice. Pulmonary haemodynamics, PA remodelling, expression of chemokines and fibroblast growth factor (FGF)-2, accumulation of macrophages to small PA and the right ventricle (RV) were examined in PH-induced WT and periostin-/- mice. Additionally, the role of periostin in the migration of macrophages, human PA smooth muscle (HPASMCs) and endothelial cells (HPMVECs) was investigated.

RESULTS

In PH induced by SuHx and MCT-P, PH and accumulation of M2 macrophage to small PA were attenuated in periostin-/- mice. PA remodelling post-SuHx treatment was also mild in periostin-/- mice compared to WT mice. Expression of macrophage-associated chemokines and FGF-2 in lung tissue, and accumulation of CD68-positive cells in the RV were less in SuHx periostin-/- than in SuHx WT mice. Periostin secretion in HPASMCs and HPMVECs was enhanced by transforming growth factor-β. Periostin also augmented macrophage, HPASMCs and HPMVECs migration. Separately, serum periostin levels were significantly elevated in patients with PH compared to healthy controls.

CONCLUSION

Periostin is involved in the development of different types of experimental PH, and may also contribute to the pathogenesis of human PH.