Ferroptosis in Myocardial Fibrosis: Mechanisms and Therapeutic Insights.

Cardiac fibrosis is a pathological hallmark of almost all forms of heart disease, characterized by excessive deposition of extracellular matrix (ECM) proteins by activated fibroblasts, leading to cardiomyocyte hypertrophy, arrhythmias, and heart failure. Current treatments, predominantly pharmacological, target signaling pathways involved in fibroblast activation but often come with side effects such as cardiac toxicities. There is a critical need for therapies that specifically target activated cardiac fibroblasts to mitigate these adverse effects. Recent advances have shown that chimeric antigen receptor (CAR)-T cells targeting fibroblast activation protein (FAP), expressed by activated fibroblasts, can significantly reduce fibrosis and improve cardiac function in mouse models. However, CAR-T cell therapies face challenges such as the requirement for large quantities of healthy primary immune cells, lengthy process, and the high cost of personalized treatments. To address these issues, we propose an innovative strategy using off-the-shelf CAR-neutrophils derived from human pluripotent stem cells (hPSCs). We hypothesize that hPSC-derived CAR-neutrophils engineered to target FAP will effectively reduce cardiac fibrosis and improve cardiac function post-injury due to their potent cytotoxic effects and ability to infiltrate infarct regions. To test this hypothesis, anti-FAP CAR hPSCs were generated by CRISPR/Cas9 genome editing and differentiated into neutrophils. The differentiated anti-FAP CAR hPSC-neutrophils exhibited molecular characteristics comparable to unmodified hPSC-neutrophils. We also established an in vitro cardiac fibrosis model utilizing a previously reported protocol for the generation of hPSC-derived epicardial fibroblasts. Importantly, our anti-FAP hPSC-neutrophils exhibited significant cytotoxicity against activated epicardial fibroblasts, while unmodified hPSC-neutrophils showed no/minimal killing efficiency. This study suggests a proof-of-concept therapeutic approach against cardiac fibrosis utilizing FAP-targeting CAR-neutrophils. This strategy can potentially be adapted to treat fibrosis in other organs, thereby having a broad and significant impact on the treatment of various fibrotic diseases, ultimately contributing to longer, healthier human lives.

The role of Smad signaling cascades in cardiac fibrosis

The emerging roles of ferroptosis in organ fibrosis and its potential therapeutic effect

Extracellular matrix remodeling and cardiac fibrosis

Cardiac fibrosis is a significant global health problem associated with almost all types of heart disease. Extensive cardiac fibrosis reduces tissue compliance and contributes to adverse outcomes, such as cardiomyocyte hypertrophy, cardiomyocyte apoptosis, and even heart failure. It is mainly associated with pathological myocardial remodeling, characterized by the excessive deposition of extracellular matrix (ECM) proteins in cardiac parenchymal tissues. In recent years, a growing body of evidence demonstrated that microRNAs (miRNAs) have a crucial role in the pathological development of cardiac fibrosis. More than sixty miRNAs have been associated with the progression of cardiac fibrosis. In this review, we summarized potential miRNAs and miRNAs-related regulatory mechanisms for cardiac fibrosis and discussed the potential clinical application of miRNAs in cardiac fibrosis.

Background: Cardiac fibrosis involves excessive deposition of extracellular matrix (ECM) proteins, leading to myocardial stiffness and remodeling, exacerbating diastolic and systolic dysfunction. Notably, cardiac fibroblast (CF) differentiation into myofibroblasts drives ECM deposition, contributing to adverse remodeling. Lipid peroxidation by 4-hydroxynonenal (4HNE) is crucial in fibrosis initiation. Our research explores the role of alternative polyadenylation (APA) in ECM production specifically the impact of 4HNE on APA-mediated modifications in CF activation. Objective: To investigate global APA events during the transition of human CFs to myofibroblasts induced by 4HNE, using the PolyA miner algorithm. Methods: Human CFs were treated with 1 or 2 µM 4HNE or vehicle control to investigate 4HNE induced heterogeneity in 3’UTR lengths. Poly(A)-click RNA sequencing and PolyA-miner analysis were used to examine 3’UTR length changes in genes related to myofibroblast activation. Results: Our analysis revealed cells treated with 1 µM 4HNE altered 236 differential APA genes (DAGs), of which 169 genes exhibited PolyAIndex and among them, 77 underwent 3’ UTR lengthening, and 92 genes underwent 3’UTR shortening. Whereas cells treated with 2µM 4HNE altered 461 DAGs of which 345 genes exhibited PolyAIndex, with 127 genes exhibiting elongation and 218 genes showing shortening. This shows, 4HNE altered 3’UTR lengths in dose dependent manner. Importantly, pathway analysis unveiled that the shortened 3’UTR lengths of genes in 4HNE treated fibroblasts were associated with TGF-β, hippo, and focal adhesion signaling pathways implicated in myofibroblast activation, whereas genes with altered elongated 3’UTR lengths were mostly linked to hedgehog signaling. Furthermore, 4HNE promoted differential APA of fibrotic genes, including fibronectin, collagen 1 α, and α-smooth muscle actin, correlating with increased protein expression. Altogether, our results identify 4HNE as an APA regulator during cardiac myofibroblast activation, though the exact mechanism remains unknown. Conclusion: This study provides novel insights into the molecular mechanisms by which 4HNE governs the transition of human CF to myofibroblasts through regulation of 3'UTR length of fibrotic genes and subsequent translational control. Understanding 4HNE-mediated APA-mediated changes in CFs may pave the way for the development of targeted therapeutic strategies to mitigate adverse outcomes in cardiac fibrosis.

Myocardial fibrosis is the excessive deposition of extracellular matrix (ECM) proteins in the cardiac interstitium leading to pathological conditions of the heart. The objective is to understand the pathophysiology of cardiac fibrosis and the quest for serum biomarkers that will assist in early diagnosis before the occurrence of major cardiac events. There are many serum biomarkers that get elevated highlighting ECM remodeling during cardiac fibrosis. Lysyl oxidase like -2 is one such ECM protein, plays a crucial role in the up-regulation of TGF - β, the transformation of cardiac fibroblast to myoblast, the migration of collagen, and cross-linking of collagen and elastin. However, assessment of lysyl oxidase like-2 (LOXL-2) in different pathologically driven cardiac fibrosis is limited. Also, none of the serum biomarkers has proved to be the most accurate diagnostic tool for assessing fibrosis independently; hence, meticulous, less invasive, and cost-effective serum biomarkers need to be scrutinized. Hence lysyl oxidase Like-2 (LOXL-2) in combination with other serum biomarkers like PICP/PINP/TIMP-1/ST-2, or Galectin-3 can be combined to assess the presence of fibrosis in the heart. This review includes the journal, articles, and research paper on cardiac fibrosis which was published in the last 10–15 years to highlight the huge gap in the treatment of cardiac fibrosis and the need for a new combination of biomarkers with better prognostic and diagnostic value.

Redox homeostasis in cardiac fibrosis: Focus on metal ion metabolism

Fibrosis is defined as the excessive deposition of extracellular matrix (ECM) proteins in the interstitium. It is an essential pathological response to chronic inflammation. ECM protein deposition is initially protective and is critical for wound healing and tissue regeneration. However, pathological cardiac remodeling in excessive and continuous tissue damage with subsequent ECM deposition results in a distorted organ architecture and significantly impacts cardiac function. In this review, we summarized and discussed the histologic features of cardiac fibrosis with the signaling factors that control it. We evaluated the origin and characteristic markers of cardiac fibroblasts. We also discussed lymphatic vessels, which have become more important in recent years to improve cardiac fibrosis.

IntroductionCardiac fibrosis after myocardial infarction (MI) is a hallmark of the failing heart. Activation of myofibroblasts after MI can lead to excessive deposition of extracellular matrix (ECM) proteins and development...

IntroductionCardiac fibrosis after myocardial infarction (MI) is a hallmark of the failing heart. Activation of myofibroblasts after MI can lead to excessive deposition of extracellular matrix (ECM) proteins and the...

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by hyperglycemia due to inadequate insulin secretion, resistance, or both. The cardiovascular complications of DM are the leading cause of morbidity and mortality in diabetic patients. There are three major types of pathophysiologic cardiac remodeling including coronary artery atherosclerosis, cardiac autonomic neuropathy, and DM cardiomyopathy in patients with DM. DM cardiomyopathy is a distinct cardiomyopathy characterized by myocardial dysfunction in the absence of coronary artery disease, hypertension, and valvular heart disease. Cardiac fibrosis, defined as the excessive deposition of extracellular matrix (ECM) proteins, is a hallmark of DM cardiomyopathy. The pathophysiology of cardiac fibrosis in DM cardiomyopathy is complex and involves multiple cellular and molecular mechanisms. Cardiac fibrosis contributes to the development of heart failure with preserved ejection fraction (HFpEF), which increases mortality and the incidence of hospitalizations. As medical technology advances, the severity of cardiac fibrosis in DM cardiomyopathy can be evaluated by non-invasive imaging modalities such as echocardiography, heart computed tomography (CT), cardiac magnetic resonance imaging (MRI), and nuclear imaging. In this review article, we will discuss the pathophysiology of cardiac fibrosis in DM cardiomyopathy, non-invasive imaging modalities to evaluate the severity of cardiac fibrosis, and therapeutic strategies for DM cardiomyopathy.

Background: In response to cardiac injury, the heart undergoes a remodeling process, which may be defined by a complex set of genomic, expression, molecular, cellular and interstitial changes, which can become maladaptive and contribute to the development of heart failure (HF). One of the most important components in cardiac remodeling is the development of fibrosis, which is characterized by excessive deposition of extracellular matrix (ECM) proteins by cardiac fibroblasts, which disrupts the myocardial architecture and function, thus predisposing the progression of cardiac diseases to HF. The small GTPase Septin4 (Sept4) has been described to regulate regeneration and apoptosis in several organs. However, the role of Sept4 in regulating the cardiac stress response is unknown. The present study was designed to investigate if Sept4 would be mediating the alterations associated with cardiac remodeling induced by cardiac pressure overload. Hypothesis: We hypothesized that Sept4 deletion prevents the fibrotic response associated with cardiac remodeling, and the development and progression of HF triggered by transverse aortic constriction (TAC). Methods: 10-week-old wild type (WT) and Sept4 knockout (KO) mice were subjected to TAC to induce cardiac pressure overload. Functional and molecular analyses on WT and KO hearts were performed either at baseline, 1- or 4-weeks post-injury timepoints. Results: After TAC injury, WT mice showed a significant reduction of cardiac function and the development of heart failure, while KO mice were able to maintain normal cardiac function. KO hearts exhibited decreased levels of cardiac ECM deposition and fibrosis compared with WT hearts. Furthermore, KO hearts were more compliant and demonstrated improved end diastolic pressure compared with their WT counterparts. The differentiation of fibroblasts into myofibroblasts was impaired in KO hearts compared with WT controls, which appeared to be associated with attenuated TGF-β-triggered signaling pathway in KO hearts after TAC injury. In line with these findings, we verified in cultured cardiac fibroblasts (CFBs) that Sept4 deletion resulted in reduced myofibroblasts differentiation and a blunted ability of CFBs to contract. Conclusion: Our results demonstrate that Sept4 is an important regulator of ECM remodeling in the heart. Sept4 deletion leads to reduced levels of cardiac fibrosis and attenuation of pressure overload-induced cardiac dysfunction. These findings highlight Sept4 as a potential target to prevent fibrosis in cardiac stress response. This study was supported by grants from the National Institutes of Health (HL155993 and HL160665). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The development of muscle hypertrophy and the excess deposition of extracellular matrix (ECM) proteins (ie, myocardial fibrosis) frequently accompany pathological cardiac remodeling. Peroxisome proliferator–activated receptors (PPARs) are ligand-activated transcription factors belonging to the nuclear factor receptor superfamily. Three different PPARs have been identified to date (PPARα, PPARβ, and PPARγ). PPARs are endogenously activated by ligands such as fatty acids and eicosanoids. PPARs are known to modulate gene expression for pathways involved in fat, lipid and glucose metabolism, inflammation, cell cycle, and immune responses.1 The genetic manipulation in mice of PPARs can lead to the modulation of cardiac muscle hypertrophy.2 The experimental use of PPAR ligands has also demonstrated their capacity to ameliorate myocardial fibrosis.3,4 However, the effect of PPAR activation on modulating cardiac fibroblast (CF) ECM turnover has not been explored. PPARγ can be activated by small molecules such as glitazones and lead to decreases in glucose and lipid serum levels. These properties of glitazones have been used for the treatment of type 2 diabetes patients for which benefits are derived not only from their ability to enhance insulin sensitivity but to ameliorate development of atherosclerosis.1 Glitazone derivatives such as rosiglitazone have also been shown to reduce myocardial infarct size after coronary artery occlusion–reperfusion.5 Evidence of improved contractile function and reduced levels of markers/mediators of inflammation accompanied the reduction in infarct size. Shiomi et al6 showed that long-term postmyocardial infarction treatment of mice with pioglitazone led to an amelioration of adverse left ventricular remodeling, improved contractile function, reduced levels of …

PurposeCardiac fibrosis is characterized by the excessive deposition of extracellular matrix (ECM) proteins and leads to the maladaptive changes in myocardium. Endothelial cells (ECs) undergoing mesenchymal transition contributes to the occurrence and development of cardiac fibrosis. CD146 is an adhesion molecule highly expressed in ECs. The present study was performed to explore the role of CD146 in modulating endothelial to mesenchymal transition (EndMT).MethodsC57BL/6 mice were subjected to subcutaneous implantation of osmotic minipump infused with angiotensin II (Ang Ⅱ). Adenovirus carrying CD146 short hairpin RNA (shRNA) or CD146 encoding sequence were infected into cultured human umbilical vein endothelial cells (HUVECs) followed by stimulation with Ang II or transforming growth factor-β1 (TGF-β1). Differentially expressed genes were revealed by RNA-sequencing (RNA-Seq) analysis. Gene expression was measured by quantitative real-time PCR, and protein expression and distribution were determined by Western blot and immunofluorescence staining, respectively.ResultsCD146 was predominantly expressed by ECs in normal mouse hearts. CD146 was upregulated in ECs but not fibroblasts and myocytes in hearts of Ang II-infused mice and in HUVECs stimulated with Ang Ⅱ. RNA-Seq analysis revealed the differentially expressed genes related to EndMT and Wnt/β-catenin signaling pathway. CD146 knockdown and overexpression facilitated and attenuated, respectively, EndMT induced by Ang II or TGF-β1. CD146 knockdown upregulated Wnt pathway-related genes including Wnt4, LEF1, HNF4A, FOXA1, SOX6, and CCND3, and increased the protein level and nuclear translocation of β-catenin.ConclusionsKnockdown of CD146 exerts promotional effects on EndMT via activating Wnt/β-catenin pathway and the upregulation of CD146 might play a protective role against EndMT and cardiac fibrosis.