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Background: Heart failure (HF), which is caused by cardiac overload and injury, is linked to significant mortality. Writers of RNA modification (WRMs) play a crucial role in the regulation of epigenetic processes involved in immune response and cardiovascular disease. However, the potential roles of these writers in the immunological milieu of HF remain unknown. Methods: We comprehensively characterized the expressions of 28 WRMs using datasets GSE145154 and GSE141910 to map the cardiac immunological microenvironment in HF patients. Based on the expression of WRMs, the immunological cells in the datasets were scored. Results: Single-cell transcriptomics analysis (GSE145154) revealed immunological dysregulation in HF as well as differential expression of WRMs in immunological cells from HF and non-HF (NHF) samples. WRM-scored immunological cells were positively correlated with the immunological response, and the high WRM score group exhibited elevated immunological cell infiltration. WRMs are involved in the differentiation of T cells and myeloid cells. WRM scores of T cell and myeloid cell subtypes were significantly reduced in the HF group compared to the NHF group. We identified a myogenesis-related resident macrophage population in the heart, Macro-MYL2, that was characterized by an increased expression of cardiomyocyte structural genes (MYL2, TNNI3, TNNC1, TCAP, and TNNT2) and was regulated by TRMT10C. Based on the WRM expression pattern, the transcriptomics data (GSE141910) identified two distinct clusters of HF samples, each with distinct functional enrichments and immunological characteristics. Conclusion: Our study demonstrated a significant relationship between the WRMs and immunological microenvironment in HF, as well as a novel resident macrophage population, Macro-MYL2, characterized by myogenesis. These results provide a novel perspective on the underlying mechanisms and therapeutic targets for HF. Further experiments are required to validate the regulation of WRMs and Macro-MYL2 macrophage subtype in the cardiac immunological milieu. [ABSTRACT FROM AUTHOR]

Cardiovascular disease remains one of the leading causes of death globally. Recent advancements in sequencing technologies have led to the identification of a unique population of macrophages within the heart, termed cardiac resident macrophages (CRMs), which exhibit self‐renewal capabilities and play crucial roles in regulating cardiac homeostasis, inflammation, as well as injury and repair processes. This literature review aims to elucidate the origin and phenotypic characteristics of CRMs, comprehensively outline their contributions to cardiac homeostasis and further summarize their functional roles and molecular mechanisms implicated in the onset and progression of cardiovascular diseases. These insights are poised to pave the way for novel therapeutic strategies centred on targeted interventions based on the distinctive properties of resident macrophages. [ABSTRACT FROM AUTHOR]

Abstract Background Heart failure (HF), which is caused by cardiac overload and injury, is linked to significant mortality. Writers of RNA modification (WRMs) play a crucial role in the regulation of epigenetic processes involved in immune response and cardiovascular disease. However, the potential roles of these writers in the immunological milieu of HF remain unknown. Methods We comprehensively characterized the expressions of 28 WRMs using datasets GSE145154 and GSE141910 to map the cardiac immunological microenvironment in HF patients. Based on the expression of WRMs, the immunological cells in the datasets were scored. Results Single-cell transcriptomics analysis (GSE145154) revealed immunological dysregulation in HF as well as differential expression of WRMs in immunological cells from HF and non-HF (NHF) samples. WRM-scored immunological cells were positively correlated with the immunological response, and the high WRM score group exhibited elevated immunological cell infiltration. WRMs are involved in the differentiation of T cells and myeloid cells. WRM scores of T cell and myeloid cell subtypes were significantly reduced in the HF group compared to the NHF group. We identified a myogenesis-related resident macrophage population in the heart, Macro-MYL2, that was characterized by an increased expression of cardiomyocyte structural genes (MYL2, TNNI3, TNNC1, TCAP, and TNNT2) and was regulated by TRMT10C. Based on the WRM expression pattern, the transcriptomics data (GSE141910) identified two distinct clusters of HF samples, each with distinct functional enrichments and immunological characteristics. Conclusion Our study demonstrated a significant relationship between the WRMs and immunological microenvironment in HF, as well as a novel resident macrophage population, Macro-MYL2, characterized by myogenesis. These results provide a novel perspective on the underlying mechanisms and therapeutic targets for HF. Further experiments are required to validate the regulation of WRMs and Macro-MYL2 macrophage subtype in the cardiac immunological milieu.

Background: A high-fat diet (HFD) contributes to various metabolic disorders and obesity, which are major contributors to cardiovascular disease. As an essential regulator for heart homeostasis, cardiac resident macrophages may go awry and contribute to cardiac pathophysiology upon HFD. Thus, to better understand how HFD induced cardiac dysfunction, this study intends to explore the transcriptional and functional changes in cardiac resident macrophages of HFD mice. Methods: C57BL/6J female mice that were 6 weeks old were fed with HFD or normal chow diet (NCD) for 16 weeks. After an evaluation of cardiac functions by echocardiography, mouse hearts were harvested and cardiac resident CCR2- macrophages were sorted, followed by Smart sequencing. Bioinformatics analysis including GO, KEGG, and GSEA analyses were employed to elucidate transcriptional and functional changes. Results: Hyperlipidemia and obesity were observed easily upon HFD. The mouse hearts also displayed more severe fibrosis and diastolic dysfunction in HFD mice. Smart sequencing and functional analysis revealed metabolic dysfunctions, especially lipid-related genes and pathways. Besides this, antigenpresentation-related gene such as Ctsf and inflammation, particularly for NFkB signaling and complement cascades, underwent drastic changes in cardiac resident macrophages. GO cellular compartment analysis was also performed and showed specific organelle enrichment trends of the involved genes. Conclusion: Dysregulated metabolism intertwines with inflammation in cardiac resident macrophages upon HFD feeding in mice, and further research on crosstalk among organelles could shed more light on potential mechanisms. [ABSTRACT FROM AUTHOR]

Cardiac resident macrophages (CRMs) are the main population of cardiac immune cells. The role of these cells in regeneration, functional remodeling, and repair after cardiac injury is always the focus of research. However, in recent years, their dynamic changes and contributions in physiological states have a significant attention. CRMs have specific phenotypes and functions in different cardiac chambers or locations of the heart and at different stages. They further show specific differentiation and development processes. The present review will summarize the new progress about the spatiotemporal distribution, potential developmental regulation, and their roles in cardiac development and aging as well as the translational potential of CRMs on cardiac diseases. Of course, the research tools for CRMs, their respective advantages and disadvantages, and key issues on CRMs will further be discussed.

Cardiovascular diseases are an array of age-related disorders, and accumulating evidence suggests a link between cardiac resident macrophages (CRMs) and the age-related disorders. However, how does CRMs alter with aging remains elusive. In the present study, aged mice (20 months old) have been employed to check for their cardiac structural and functional alterations, and the changes in the proportion of CRM subsets as well, followed by sorting of CRMs, including C-C Motif Chemokine Receptor 2 (CCR2)+ and CCR2– CRMs, which were subjected to Smart-Seq. Integrated analysis of the Smart-Seq data with three publicly available single-cell RNA-seq datasets revealed that inflammatory genes were drastic upregulated for both CCR2+ and CCR2– CRMs with aging, but genes germane to wound healing were downregulated for CCR2– CRMs, suggesting the differential functions of these two subsets. More importantly, inflammatory genes involved in damage sensing, complement cascades, and phagocytosis were largely upregulated in CCR2– CRMs, implying the imbalance of inflammatory response upon aging. Our work provides a comprehensive framework and transcriptional resource for assessing the impact of aging on CRMs with a potential for further understanding cardiac aging. [ABSTRACT FROM AUTHOR]

Cardiac resident macrophages (CRMs) are the main population of cardiac immune cells. The role of these cells in regeneration, functional remodeling, and repair after cardiac injury is always the focus of research. However, in recent years, their dynamic changes and contributions in physiological states have a significant attention. CRMs have specific phenotypes and functions in different cardiac chambers or locations of the heart and at different stages. They further show specific differentiation and development processes. The present review will summarize the new progress about the spatiotemporal distribution, potential developmental regulation, and their roles in cardiac development and aging as well as the translational potential of CRMs on cardiac diseases. Of course, the research tools for CRMs, their respective advantages and disadvantages, and key issues on CRMs will further be discussed. CRM subsets reside in different anatomical niches with high spatiotemporal heterogeneity and play different roles in cardiac development and pathophysiology. [Display omitted] [ABSTRACT FROM AUTHOR]

Cardiac resident macrophages (CRMs) are integral components of the heart and play significant roles in cardiac development, steady‐state, and injury. Advances in sequencing technology have revealed that CRMs are a highly heterogeneous population, with significant differences in phenotype and function at different developmental stages and locations within the heart. In addition to research focused on diseases, recent years have witnessed a heightened interest in elucidating the involvement of CRMs in heart development and the maintenance of cardiac function. In this review, we primarily concentrated on summarizing the developmental trajectories, both spatial and temporal, of CRMs and their impact on cardiac development and steady‐state. Moreover, we discuss the possible factors by which the cardiac microenvironment regulates macrophages from the perspectives of migration, proliferation, and differentiation under physiological conditions. Gaining insight into the spatiotemporal heterogeneity and regulatory mechanisms of CRMs is of paramount importance in comprehending the involvement of macrophages in cardiac development, injury, and repair, and also provides new ideas and therapeutic methods for treating heart diseases. [ABSTRACT FROM AUTHOR]

Acute myocardial infarction (MI) is a prevalent and highly fatal global disease. Despite significant reduction in mortality rates with standard treatment regimens, the risk of heart failure (HF) remains high, necessitating innovative approaches to protect cardiac function and prevent HF progression. Cardiac resident macrophages (cMacs) have emerged as key regulators of the pathophysiology following MI. cMacs are a heterogeneous population composed of subsets with different lineage origins and gene expression profiles. Several critical aspects of post-MI pathophysiology have been shown to be regulated by cMacs, including recruitment of peripheral immune cells, clearance and replacement of damaged myocardial cells. Furthermore, cMacs play a crucial role in regulating cardiac fibrosis, risk of arrhythmia, energy metabolism, as well as vascular and lymphatic remodeling. Given the multifaceted roles of cMacs in post-MI pathophysiology, targeting cMacs represents a promising therapeutic strategy. Finally, we discuss novel treatment strategies, including using nanocarriers to deliver drugs to cMacs or using cell therapies to introduce exogenous protective cMacs into the heart. [ABSTRACT FROM AUTHOR]

Cardiac-resident macrophages (CRMs) play important roles in homeostasis, cardiac function, and remodeling. Although CRMs play critical roles in cardiac regeneration of neonatal mice, their roles are yet to be fully elucidated. Therefore, this study aimed to investigate the dynamic changes of CRMs during cardiac ontogeny and analyze the phenotypic and functional properties of CRMs in the promotion of cardiac regeneration. During mouse cardiac ontogeny, four CRM subsets exist successively: CX3CR1+CCR2–Ly6C–MHCII– (MP1), CX3CR1lowCCR2lowLy6C–MHCII– (MP2), CX3CR1–CCR2+Ly6C+MHCII– (MP3), and CX3CR1+CCR2–Ly6C–MHCII+ (MP4). MP1 cluster has different derivations (yolk sac, fetal liver, and bone marrow) and multiple functions population. Embryonic and neonatal-derived-MP1 directly promoted cardiomyocyte proliferation through Jagged-1–Notch1 axis and significantly ameliorated cardiac injury following myocardial infarction. MP2/3 subsets could survive throughout adulthood. MP4, the main population in adult mouse hearts, contributed to inflammation. During ontogeny, MP1 can convert into MP4 triggered by changes in the cellular redox state. These findings delineate the evolutionary dynamics of CRMs under physiological conditions and found direct evidence that embryonic and neonatal-derived CRMs regulate cardiomyocyte proliferation. Our findings also shed light on cardiac repair following injury.

Cardiac-resident macrophages (CRMs) play important roles in homeostasis, cardiac function, and remodeling. Although CRMs play critical roles in cardiac regeneration of neonatal mice, their roles are yet to be fully elucidated. Therefore, this study aimed to investigate the dynamic changes of CRMs during cardiac ontogeny and analyze the phenotypic and functional properties of CRMs in the promotion of cardiac regeneration. During mouse cardiac ontogeny, four CRM subsets exist successively: CX 3 CR1+CCR2–Ly6C–MHCII– (MP1), CX 3 CR1lowCCR2lowLy6C–MHCII– (MP2), CX 3 CR1–CCR2+Ly6C+MHCII– (MP3), and CX 3 CR1+CCR2–Ly6C–MHCII+ (MP4). MP1 cluster has different derivations (yolk sac, fetal liver, and bone marrow) and multiple functions population. Embryonic and neonatal-derived-MP1 directly promoted cardiomyocyte proliferation through Jagged-1–Notch1 axis and significantly ameliorated cardiac injury following myocardial infarction. MP2/3 subsets could survive throughout adulthood. MP4, the main population in adult mouse hearts, contributed to inflammation. During ontogeny, MP1 can convert into MP4 triggered by changes in the cellular redox state. These findings delineate the evolutionary dynamics of CRMs under physiological conditions and found direct evidence that embryonic and neonatal-derived CRMs regulate cardiomyocyte proliferation. Our findings also shed light on cardiac repair following injury. The embryonic and neonatal-derived cardiac-resident macrophages (CRMs) facilitated cardiomyocyte proliferation through Jagged-1–Notch1 axis. After birth, microenvironment changes caused switch or renewal of CRMs, which resulted in the loss of their proliferative potential. [Display omitted] [ABSTRACT FROM AUTHOR]

After acute myocardial infarction (AMI), intercellular communication is crucial for maintaining cardiac homeostasis and patient survival. Exosomes secreted by cardiomyocytes serve as carriers for transporting microRNA(miRNAs), participating in intercellular signaling and the regulation of cardiac function. This study aims to investigate the role of exosomal microRNA-30a(miR-30a) during AMI and its underlying mechanisms. AMI was induced by permanent ligation of the left anterior descending (LAD) artery in C57BL/6 mice. The expression of miR-30a in mice was respectively enhanced and inhibited by administering agomiR-30a and antagomiR-30a. Using HL-1 cardiomyocytes and RAW264.7 macrophages for in vitro experiments, HL-1 cardiomyocytes were cultured under hypoxic conditions to induce ischemic injury. Following isolation and injection of exosomals, a variety of validation methods were utilized to assess the expression of miR-30a, and investigate the effects of enriched exosomal miR-30a on the state of cardiomyocytes. After AMI, the level of exosomal miR-30a in the serum of mice significantly increased and was highly enriched in cardiac tissue. Cardiomyocytes treated with agomiR-30a and miR-30a-enriched exosomes exhibited inhibition of cell autophagy, increased cell apoptosis, mice showed an larger myocardial infarct area and poorer cardiac function. Exosomes released from hypoxic cardiomyocytes transferred miR-30a to cardiac resident macrophages, promoting the polarization into pro-inflammatory M1 macrophages. In conclusion, murine exosomal miR-30a exacerbates cardiac dysfunction post-AMI by disrupting the autophagy-apoptosis balance in cardiomyocytes and polarizing cardiac resident macrophages into pro-inflammatory M1 macrophages. Modulating the expression of miR-30a may reduce cardiac damage following AMI, and targeting exosomal miR-30a could be a potential therapeutic approach for AMI. • Exosomal miR-30a aggravates cardiac dysfunction post-AMI by inhibiting cardiomyocyte autophagy and promoting apoptosis. • Post-AMI, miR-30a-enriched exosomes are transferred between cardiomyocytes and macrophages, influencing cell fate and inflammation. • Targeting miR-30a may offer therapeutic potential to reduce cardiac damage and improve outcomes after acute myocardial infarction. [ABSTRACT FROM AUTHOR]

Cardiac resident macrophages (CRMs) are essential in maintaining the balance of the immune homeostasis in the heart. One of the main factors in the progression of cardiovascular diseases, such as myocarditis, myocardial infarction(MI), and heart failure(HF), is the imbalance in the regulatory mechanisms of CRMs. Recent studies have reported novel heterogeneity and spatiotemporal complexity of CRMs, and their role in maintaining cardiac immune homeostasis and treating cardiovascular diseases. In this review, we focus on the functions of CRMs, including immune surveillance, immune phagocytosis, and immune metabolism, and explore the impact of CRM's homeostasis imbalance on cardiac injury and cardiac repair. We also discuss the therapeutic approaches linked to CRMs. The immunomodulatory strategies targeting CRMs may be a therapeutic approach for the treatment of cardiovascular disease. • Cardiac resident macrophages (CRMs) promote tissue development and homeostasis. • CRMs have the functions of immune surveillance, immune phagocytosis, and immune metabolism. • The dynamic relationship between the different functions of CRMs is balanced to coordinate cardiac immune homeostasis. • Targeting CRMs may be a therapeutic potential approach for the treatment of cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Background: A high-fat diet (HFD) contributes to various metabolic disorders and obesity, which are major contributors to cardiovascular disease. As an essential regulator for heart homeostasis, cardiac resident macrophages may go awry and contribute to cardiac pathophysiology upon HFD. Thus, to better understand how HFD induced cardiac dysfunction, this study intends to explore the transcriptional and functional changes in cardiac resident macrophages of HFD mice., Methods: C57BL/6J female mice that were 6 weeks old were fed with HFD or normal chow diet (NCD) for 16 weeks. After an evaluation of cardiac functions by echocardiography, mouse hearts were harvested and cardiac resident CCR2 - macrophages were sorted, followed by Smart sequencing. Bioinformatics analysis including GO, KEGG, and GSEA analyses were employed to elucidate transcriptional and functional changes., Results: Hyperlipidemia and obesity were observed easily upon HFD. The mouse hearts also displayed more severe fibrosis and diastolic dysfunction in HFD mice. Smart sequencing and functional analysis revealed metabolic dysfunctions, especially lipid-related genes and pathways. Besides this, antigen-presentation-related gene such as Ctsf and inflammation, particularly for NF-κB signaling and complement cascades, underwent drastic changes in cardiac resident macrophages. GO cellular compartment analysis was also performed and showed specific organelle enrichment trends of the involved genes., Conclusion: Dysregulated metabolism intertwines with inflammation in cardiac resident macrophages upon HFD feeding in mice, and further research on crosstalk among organelles could shed more light on potential mechanisms., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Zhu, Liu, Xia, Wang, Du, Wu, Wang, Wang, Shen, Wei and Xu.)

Acute myocardial infarction (MI) is a prevalent and highly fatal global disease. Despite significant reduction in mortality rates with standard treatment regimens, the risk of heart failure (HF) remains high, necessitating innovative approaches to protect cardiac function and prevent HF progression. Cardiac resident macrophages (cMacs) have emerged as key regulators of the pathophysiology following MI. cMacs are a heterogeneous population composed of subsets with different lineage origins and gene expression profiles. Several critical aspects of post-MI pathophysiology have been shown to be regulated by cMacs, including recruitment of peripheral immune cells, clearance and replacement of damaged myocardial cells. Furthermore, cMacs play a crucial role in regulating cardiac fibrosis, risk of arrhythmia, energy metabolism, as well as vascular and lymphatic remodeling. Given the multifaceted roles of cMacs in post-MI pathophysiology, targeting cMacs represents a promising therapeutic strategy. Finally, we discuss novel treatment strategies, including using nanocarriers to deliver drugs to cMacs or using cell therapies to introduce exogenous protective cMacs into the heart., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Chen, Wang, Liu and Hu.)