Novel roles of immunometabolism and nonmyocyte metabolism in cardiac remodeling and injury

Metabolic Homeostasis of Immune Cells Modulates Cardiovascular Diseases

Recent investigations into the mechanisms underlying inflammation have highlighted the pivotal role of immune cells in regulating cardiac pathophysiology. Notably, these immune cells modulate cardiac processes through alternations in intracellular metabolism, including glycolysis and oxidative phosphorylation, whereas the extracellular metabolic environment is changed during cardiovascular disease, influencing function of immune cells. This dynamic interaction between immune cells and their metabolic environment has given rise to the novel concept of "immune metabolism". Consequently, both the extracellular and intracellular metabolic environment modulate the equilibrium between anti- and pro-inflammatory responses. This regulatory mechanism subsequently influences the processes of myocardial ischemia, cardiac fibrosis, and cardiac remodeling, ultimately leading to a series of cardiovascular events. This review examines how local microenvironmental and systemic environmental changes induce metabolic reprogramming in immune cells and explores the subsequent effects of aberrant activation or polarization of immune cells in the progression of cardiovascular disease. Finally, we discuss potential therapeutic strategies targeting metabolism to counteract abnormal immune activation.

Mitochondrial dysfunction and calcium homeostasis in heart failure: Exploring the interplay between oxidative stress and cardiac remodeling for future therapeutic innovations

Heart failure (HF) is a multifaceted clinical syndrome characterized by the heart's inability to pump sufficient blood to meet the body's metabolic demands. It arises from various etiologies, including myocardial injury, hypertension, and valvular heart disease. A critical aspect of HF pathophysiology involves mitochondrial dysfunction, particularly concerning calcium (Ca2+) homeostasis and oxidative stress. This review highlights the pivotal role of excess mitochondrial Ca2+ in exacerbating oxidative stress, contributing significantly to HF progression. Novel insights are provided regarding the mechanisms by which mitochondrial Ca2+ overload leads to increased production of reactive oxygen species (ROS) and impaired cellular function. Despite this understanding, key gaps in research remain, particularly in elucidating the complex interplay between mitochondrial dynamics and oxidative stress across different HF phenotypes. Furthermore, therapeutic strategies targeting mitochondrial dysfunction are still in their infancy, with limited applications in clinical practice. By summarizing recent findings and identifying these critical research gaps, this review aims to pave the way for innovative therapeutic approaches that improve the management of heart failure, ultimately enhancing patient outcomes through targeted interventions.

Regulation of fibroblast phenotype in osteoarthritis using CDKN1A-loaded copper sulfide nanoparticles delivered by mesenchymal stem cells

This study aimed to investigate the regulation of fibroblast phenotypes by mesenchymal stem cells (MSCs) delivering copper sulfide (CuS) nanoparticles (NPs) loaded with CDKN1A plasmids and their role in cartilage repair during osteoarthritis (OA). Single-cell RNA sequencing data from the GEO database were analyzed to identify subpopulations within the OA immune microenvironment. Quality control, filtering, principal component analysis (PCA) dimensionality reduction, and tSNE clustering were performed to obtain detailed cell subtypes. Pseudotime analysis was used to understand the developmental trajectory of fibroblasts, and GO/KEGG enrichment analyses highlighted biological processes related to fibroblast function. Transcriptomic data and WGCNA identified CDKN1A as a key regulatory gene. A biomimetic CuS@CDKN1A nanosystem was constructed and loaded into MSCs to create MSCs@CuS@CDKN1A. The characterization of this system confirmed its efficient cellular uptake by fibroblasts. In vitro experiments demonstrated that MSCs@CuS@CDKN1A significantly modulated fibroblast phenotypes and improved the structure, proliferation, reduced apoptosis, and enhanced migration of IL-1β-stimulated chondrocytes. In vivo, an OA mouse model was treated with intra-articular injections of MSCs@CuS@CDKN1A. Micro-CT scans revealed a significant reduction in osteophyte formation and improved joint space compared with control groups. Histological analysis, including H&E, Safranin O-Fast Green, and toluidine blue staining, confirmed improved cartilage integrity, whereas the International Osteoarthritis Research Society (OARSI) scoring indicated reduced disease severity. Immunofluorescence showed upregulated CDKN1A expression, decreased MMP13, and reduced α-SMA expression in fibroblast subtypes. Major organs exhibited no signs of toxicity, confirming the biocompatibility and safety of the treatment. These findings suggest that MSCs@CuS@CDKN1A can effectively regulate fibroblast activity and promote cartilage repair, providing a promising therapeutic strategy for OA treatment.NEW & NOTEWORTHY This study introduces MSCs@CuS@CDKN1A, a nanoengineered MSC platform that targets fibroblast phenotypes in osteoarthritis (OA). By modulating CDKN1A expression, this innovative approach not only enhances cartilage repair but also effectively mitigates fibroblast-driven inflammation, marking a significant advancement in OA therapeutics with demonstrated efficacy and biocompatibility.

Cardiometabolic Index is associated with heart failure: a cross-sectional study based on NHANES

Introduction

Heart failure is a complex syndrome characterized by impaired cardiac function. Despite improvements in treatment, the prevalence of heart failure continues to rise. The Cardiometabolic Index (CMI), a novel measure combining abdominal obesity and lipid levels, has emerged as a potential predictor of cardiac metabolic risk.

Methods

We analyzed data from the National Health and Nutrition Examination Survey (NHANES) involving 22,586 participants to investigate the association between CMI and heart failure. Multivariable logistic regression models and RCS analysis were used to explore the association between heart failure and CMI after adjusting for potential confounders. Subgroup analyses were performed among populations with different demographic and clinical characteristics.

Results

Our results revealed a significant positive correlation between CMI and heart failure, with odds ratios of 2.77 and 1.87 for the highest quartile after adjusting for confounders. Subgroup analyses indicated heightened risks among older adults and those with hypertension or diabetes. ROC curve analysis demonstrated that CMI offers good diagnostic value for heart failure, surpassing traditional measures like BMI.

Discussion

Our findings suggest that CMI is a valuable tool for assessing the risk of heart failure, particularly in individuals with increased abdominal obesity or abnormal lipid profiles. This highlights the importance of addressing cardiac metabolic health in both prevention and treatment strategies for heart failure. Future research should focus on exploring causal relationships and refining predictive models that incorporate CMI to enhance early detection and intervention.

Cardiac Fibroblastic Niches in Homeostasis and Inflammation

Fibroblasts are essential for building and maintaining the structural integrity of all organs. Moreover, fibroblasts can acquire an inflammatory phenotype to accommodate immune cells in specific niches and to provide migration, differentiation, and growth factors. In the heart, balancing of fibroblast activity is critical for cardiac homeostasis and optimal organ function during inflammation. Fibroblasts sustain cardiac homeostasis by generating local niche environments that support housekeeping functions and by actively engaging in intercellular cross talk. During inflammatory perturbations, cardiac fibroblasts rapidly switch to an inflammatory state and actively communicate with infiltrating immune cells to orchestrate immune cell migration and activity. Here, we summarize the current knowledge on the molecular landscape of cardiac fibroblasts, focusing on their dual role in promoting tissue homeostasis and modulating immune cell-cardiomyocyte interaction. In addition, we discuss potential future avenues for manipulating cardiac fibroblast activity during myocardial inflammation.

Cardiac fibrogenesis: an immuno-metabolic perspective

Cardiac fibrosis is a major and complex pathophysiological process that ultimately culminates in cardiac dysfunction and heart failure. This phenomenon includes not only the replacement of the damaged tissue by a fibrotic scar produced by activated fibroblasts/myofibroblasts but also a spatiotemporal alteration of the structural, biochemical, and biomechanical parameters in the ventricular wall, eliciting a reactive remodeling process. Though mechanical stress, post-infarct homeostatic imbalances, and neurohormonal activation are classically attributed to cardiac fibrosis, emerging evidence that supports the roles of immune system modulation, inflammation, and metabolic dysregulation in the initiation and progression of cardiac fibrogenesis has been reported. Adaptive changes, immune cell phenoconversions, and metabolic shifts in the cardiac nonmyocyte population provide initial protection, but persistent altered metabolic demand eventually contributes to adverse remodeling of the heart. Altered energy metabolism, mitochondrial dysfunction, various immune cells, immune mediators, and cross-talks between the immune cells and cardiomyocytes play crucial roles in orchestrating the transdifferentiation of fibroblasts and ensuing fibrotic remodeling of the heart. Manipulation of the metabolic plasticity, fibroblast-myofibroblast transition, and modulation of the immune response may hold promise for favorably modulating the fibrotic response following different cardiovascular pathological processes. Although the immunologic and metabolic perspectives of fibrosis in the heart are being reported in the literature, they lack a comprehensive sketch bridging these two arenas and illustrating the synchrony between them. This review aims to provide a comprehensive overview of the intricate relationship between different cardiac immune cells and metabolic pathways as well as summarizes the current understanding of the involvement of immune-metabolic pathways in cardiac fibrosis and attempts to identify some of the previously unaddressed questions that require further investigation. Moreover, the potential therapeutic strategies and emerging pharmacological interventions, including immune and metabolic modulators, that show promise in preventing or attenuating cardiac fibrosis and restoring cardiac function will be discussed.

Cardiac macrophage metabolism in health and disease

Cardiac macrophages are essential mediators of cardiac development, tissue homeostasis, and response to injury. Cell-intrinsic shifts in metabolism and availability of metabolites regulate macrophage function. The human and mouse heart contain a heterogeneous compilation of cardiac macrophages that are derived from at least two distinct lineages. In this review, we detail the unique functional roles and metabolic profiles of tissue-resident and monocyte-derived cardiac macrophages during embryonic development and adult tissue homeostasis and in response to pathologic and physiologic stressors. We discuss the metabolic preferences of each macrophage lineage and how metabolism influences monocyte fate specification. Finally, we highlight the contribution of cardiac macrophages and derived metabolites on cell-cell communication, metabolic health, and disease pathogenesis.

Cardiac cell senescence: molecular mechanisms, key proteins and therapeutic targets

Cardiac aging, particularly cardiac cell senescence, is a natural process that occurs as we age. Heart function gradually declines in old age, leading to continuous heart failure, even in people without a prior history of heart disease. To address this issue and improve cardiac cell function, it is crucial to investigate the molecular mechanisms underlying cardiac senescence. This review summarizes the main mechanisms and key proteins involved in cardiac cell senescence. This review further discusses the molecular modulators of cellular senescence in aging hearts. Furthermore, the discussion will encompass comprehensive descriptions of the key drugs, modes of action and potential targets for intervention in cardiac senescence. By offering a fresh perspective and comprehensive insights into the molecular mechanisms of cardiac senescence, this review seeks to provide a fresh perspective and important theoretical foundations for the development of drugs targeting this condition.

Metabolism Serves as a Bridge Between Cardiomyocytes and Immune Cells in Cardiovascular Diseases

Metabolic disorders of cardiomyocytes play an important role in the progression of various cardiovascular diseases. Metabolic reprogramming can provide ATP to cardiomyocytes and protect them during diseases, but this transformation also leads to adverse consequences such as oxidative stress, mitochondrial dysfunction, and eventually aggravates myocardial injury. Moreover, abnormal accumulation of metabolites induced by metabolic reprogramming of cardiomyocytes alters the cardiac microenvironment and affects the metabolism of immune cells. Immunometabolism, as a research hotspot, is involved in regulating the phenotype and function of immune cells. After myocardial injury, both cardiac resident immune cells and heart-infiltrating immune cells significantly contribute to the inflammation, repair and remodeling of the heart. In addition, metabolites generated by the metabolic reprogramming of immune cells can further affect the microenvironment, thereby affecting the function of cardiomyocytes and other immune cells. Therefore, metabolic reprogramming and abnormal metabolite levels may serve as a bridge between cardiomyocytes and immune cells, leading to the development of cardiovascular diseases. Herein, we summarize the metabolic relationship between cardiomyocytes and immune cells in cardiovascular diseases, and the effect on cardiac injury, which could be therapeutic strategy for cardiovascular diseases, especially in drug research.

Cardiac Metabolism

The heart is composed of a heterogeneous mixture of cellular components perfectly intermingled and able to integrate common environmental signals to ensure proper cardiac function and performance. Metabolism defines a cell context-dependent signature that plays a critical role in survival, proliferation, or differentiation, being a recognized master piece of organ biology, modulating homeostasis, disease progression, and adaptation to tissue damage. The heart is a highly demanding organ, and adult cardiomyocytes require large amount of energy to fulfill adequate contractility. However, functioning under oxidative mitochondrial metabolism is accompanied with a concomitant elevation of harmful reactive oxygen species that indeed contributes to the progression of several cardiovascular pathologies and hampers the regenerative capacity of the mammalian heart. Cardiac metabolism is dynamic along embryonic development and substantially changes as cardiomyocytes mature and differentiate within the first days after birth. During early stages of cardiogenesis, anaerobic glycolysis is the main energetic program, while a progressive switch toward oxidative phosphorylation is a hallmark of myocardium differentiation. In response to cardiac injury, different signaling pathways participate in a metabolic rewiring to reactivate embryonic bioenergetic programs or the utilization of alternative substrates, reflecting the flexibility of heart metabolism and its central role in organ adaptation to external factors. Despite the well-established metabolic pattern of fetal, neonatal, and adult cardiomyocytes, our knowledge about the bioenergetics of other cardiac populations like endothelial cells, cardiac fibroblasts, or immune cells is limited. Considering the close intercellular communication and the influence of nonautonomous cues during heart development and after cardiac damage, it will be fundamental to better understand the metabolic programs in different cardiac cells in order to develop novel interventional opportunities based on metabolic rewiring to prevent heart failure and improve the limited regenerative capacity of the mammalian heart.

The Role of Innate Immune Cells in Cardiac Injury and Repair: A Metabolic Perspective

PURPOSE OF REVIEW

Recent technological advances have identified distinct subpopulations and roles of the cardiac innate immune cells, specifically macrophages and neutrophils. Studies on distinct metabolic pathways of macrophage and neutrophil in cardiac injury are expanding. Here, we elaborate on the roles of cardiac macrophages and neutrophils in concomitance with their metabolism in normal and diseased hearts.

RECENT FINDINGS

Single-cell techniques combined with fate mapping have identified the clusters of innate immune cell subpopulations present in the resting and diseased hearts. We are beginning to know about the presence of cardiac resident macrophages and their functions. Resident macrophages perform cardiac homeostatic roles, whereas infiltrating neutrophils and macrophages contribute to tissue damage during cardiac injury with eventual role in repair. Prior studies show that metabolic pathways regulate the phenotypes of the macrophages and neutrophils during cardiac injury. Profiling the metabolism of the innate immune cells, especially of resident macrophages during chronic and acute cardiac diseases, can further the understanding of cardiac immunometabolism.

Targeting immunometabolism during cardiorenal injury: roles of conventional and alternative macrophage metabolic fuels

Macrophages play critical roles in mediating and resolving tissue injury as well as tissue remodeling during cardiorenal disease. Altered immunometabolism, particularly macrophage metabolism, is a critical underlying mechanism of immune dysfunction and inflammation, particularly in individuals with underlying metabolic abnormalities. In this review, we discuss the critical roles of macrophages in cardiac and renal injury and disease. We also highlight the roles of macrophage metabolism and discuss metabolic abnormalities, such as obesity and diabetes, which may impair normal macrophage metabolism and thus predispose individuals to cardiorenal inflammation and injury. As the roles of macrophage glucose and fatty acid metabolism have been extensively discussed elsewhere, we focus on the roles of alternative fuels, such as lactate and ketones, which play underappreciated roles during cardiac and renal injury and heavily influence macrophage phenotypes.

Mechanical stress regulates the mechanotransduction and metabolism of cardiac fibroblasts in fibrotic cardiac diseases

Fibrotic cardiac diseases are characterized by myocardial fibrosis that results in maladaptive cardiac remodeling. Cardiac fibroblasts (CFs) are the main cell type responsible for fibrosis. In response to stress or injury, intrinsic CFs develop into myofibroblasts and produce excess extracellular matrix (ECM) proteins. Myofibroblasts are mechanosensitive cells that can detect changes in tissue stiffness and respond accordingly. Previous studies have revealed that some mechanical stimuli control fibroblast behaviors, including ECM formation, cell migration, and other phenotypic traits. Further, metabolic alteration is reported to regulate fibrotic signaling cascades, such as the transforming growth factor-β pathway and ECM deposition. However, the relationship between metabolic changes and mechanical stress during fibroblast-to-myofibroblast transition remains unclear. This review aims to elaborate on the crosstalk between mechanical stress and metabolic changes during the pathological transition of cardiac fibroblasts.

Cardiac remodelling - Part 1: From cells and tissues to circulating biomarkers. A review from the Study Group on Biomarkers of the Heart Failure Association of the European Society of Cardiology

Cardiac remodelling refers to changes in left ventricular structure and function over time, with a progressive deterioration that may lead to heart failure (HF) development (adverse remodelling) or vice versa a recovery (reverse remodelling) in response to HF treatment. Adverse remodelling predicts a worse outcome, whilst reverse remodelling predicts a better prognosis. The geometry, systolic and diastolic function and electric activity of the left ventricle are affected, as well as the left atrium and on the long term even right heart chambers. At a cellular and molecular level, remodelling involves all components of cardiac tissue: cardiomyocytes, fibroblasts, endothelial cells and leucocytes. The molecular, cellular and histological signatures of remodelling may differ according to the cause and severity of cardiac damage, and clearly to the global trend toward worsening or recovery. These processes cannot be routinely evaluated through endomyocardial biopsies, but may be reflected by circulating levels of several biomarkers. Different classes of biomarkers (e.g. proteins, non-coding RNAs, metabolites and/or epigenetic modifications) and several biomarkers of each class might inform on some aspects on HF development, progression and long-term outcomes, but most have failed to enter clinical practice. This may be due to the biological complexity of remodelling, so that no single biomarker could provide great insight on remodelling when assessed alone. Another possible reason is a still incomplete understanding of the role of biomarkers in the pathophysiology of cardiac remodelling. Such role will be investigated in the first part of this review paper on biomarkers of cardiac remodelling.

The mechanism behind BAF60c in myocardial metabolism in rats with heart failure is through the PGC1α-PPARα-mTOR signaling pathway

Metabolic remodeling in heart failure (HF) is a type of overload cardiomyopathy caused by insufficient energy supply or an imbalance of glucose and lipid metabolism. Therefore, metabolic pathways may serve as potential targets for HF treatment. BRM-associated factor (BAF) 60c (also known as smarcd3) promotes the transformation of oxidative muscle fibers to glycolytic muscle fibers. Our study aimed to test whether BAF60c and the PGC1α-PPARα-mTOR pathway interact to affect myocardial metabolism in HF rats. Established rat models of HF were injected with BAF60c low or overexpression plasmids to assess cardiac contractile proteins, energy metabolism, oxidative metabolism, glycolysis, high-energy phosphate content, mitochondrial function, and apoptosis. BAF60c overexpression/siRNA plasmid was transfected into H9C2 cells. These results suggest that HF rats present decreased levels of BAF60c, increased glycolysis, and reduced levels of cardiac contractile proteins, PGC1α, PPARα, and oxidative metabolism. Overexpression of BAF60c maintained the balance between oxidative metabolism and glycolysis and activated the PGC1α-PPARα-mTOR pathway. PGC1α interacted with BAF60c, and overexpression of PGC1α decreased BAF60c knockdown, damaging H9C2 cells. Collectively, overexpression of BAF60c activated the PGC1α-PPARα-mTOR pathway, maintained the oxidative metabolism/glycolysis balance, and improved mitochondrial function in HF rats. This study offers novel insights into HF treatment.

Immune cells in cardiac homeostasis and disease: emerging insights from novel technologies

The increasing use of single-cell immune profiling and advanced microscopic imaging technologies has deepened our understanding of the cardiac immune system, confirming that the heart contains a broad repertoire of innate and adaptive immune cells. Leucocytes found in the healthy heart participate in essential functions to preserve cardiac homeostasis, not only by defending against pathogens but also by maintaining normal organ function. In pathophysiological conditions, cardiac inflammation is implicated in healing responses after ischaemic or non-ischaemic cardiac injury. The aim of this review is to provide a concise overview of novel methodological advancements to the non-expert readership and summarize novel findings on immune cell heterogeneity and functions in cardiac disease with a focus on myocardial infarction as a prototypic example. In addition, we will briefly discuss how biological sex modulate the cardiac immune response. Finally, we will highlight emerging concepts for novel therapeutic applications, such as targeting immunometabolism and nanomedicine.