Cardiac Macrophages Research Articles

O17 THE PROGRESSION OF HYPERTENSION WITH OBESITY AND DIABETES FAVORS CARDIAC PRO-INFLAMMATORY MACROPHAGES AND DIASTOLIC DYSFUNCTION

Background: In most patients, hypertension (HT) is accompanied by obesity and diabetes. Cell-specific mechanisms like accumulation of macrophages, and dysregulation of innate immune pathways play important roles in cardiac remodeling (CR). Macrophages (Mo) exhibit phenotypic heterogeneity in response to tissue micro-environment. It is unknown whether in the heart the subpopulations of pro-inflammatory Mo (CCR2+MHCII+) and resident repair Mo (CCR2-MHCII+ and CCR2-MHCII-) differ in the development of the chronic HT, obesity and diabetes. Objective. To determine in male with HT and or obesity and diabetes, the pro-inflammatory cardiac Mo derived from monocytes (CCR2+MHCII+) and the resident repair Mo (CCR2-MHCII+ and CCR2- MHCII-). Methods: 12-week-old male C57BL/6N mice were assigned to experimental groups: control diet, high-fat diet (HFD, 60% kcal from fat), L-NAME (L,0.65 g/L in drinking water) and HFD+L for 5 and 15 weeks. Body weight (BW), systolic (SBP) and diastolic blood pressure, glucose and exercise capacity (EC), cardiac function and cardiac Mo CCR2+MHCII+, CCR2-MHCII+, CCR2- MHCII- were determined. Results: (mean ± SEM, n=9-12). During 15 weeks, HFD and HFD+L groups showed significantly higher BW and glucose intolerance vs. control and L (p <0.001, F=28.4; p<0.001, F=10.3, respectively). EC as lower in the HFD and HFD+L groups compared to control and L (p<0.059). Echocardiographic parameters showed a significant increase in the size of the left atrium (p<0.001, F=38.9) and diastolic dysfunction in the HFD+L group vs control, HFD and L (p<0.001, F=35.6). No changes in ejection fraction and shortening fraction. The thickness of the septal wall and posterior wall was significantly greater in the HFD+L and HFD groups (p<0.0001, F=10.6 and p<0.0001, F=14.6, respectively). The L hearts showed a significant increase in CCR2-MHCII- (p<0.0001, F=68.6) and a significant decrease in CCR2+ MHCII+ (p<0.001, F=13.7), compared to the control and HFD groups. Conclusion: The progression of HT with obesity and diabetes favors cardiac pro-inflammatory macrophages and diastolic dysfunction.

O15 DIFFERENTIAL CARDIAC MACROPHAGE POLARIZATION IS ASSOCIATED WITH BETTER PRECLINICAL MARKERS IN FEMALE SEX VERSUS MALE SEX WITH HYPERTENSION AND METABOLIC SYNDROME

Background: Women compared to men with hypertension (HT) and metabolic syndrome (MS) exhibit better clinical outcomes. In the preclinical model of HT-MS, female mice develop attenuated cardiac remodeling (CRM) compared to male mice (not mediated by sex hormones). Male cardiac macrophages (Mo) from mice are more susceptible to inflammatory stimuli. It is unknown whether subpopulations of cardiac pro-inflammatory Mo and resident repair Mo differ between males and females. Purpose: To characterize, in male and female mice with HT-MS, the cardiac pro-inflammatory cardiac Mo derived from monocytes (CCR2+MHCII+) and the resident repair Mo (CCR2-MHCII+ and CCR2- MHCII-). Methods: 12-week-old male and female C57BL/6N mice were assigned to experimental groups: high-fat diet + L-NAME or control diet. Body weight (BW), systolic (SBP) and diastolic (DBP) blood pressure, glucose and exercise tolerance, cardiac function and cardiac Mo CCR2+MHCII+, CCR2-MHCII+, CCR2- MHCII- were determined. Results: (mean ± SEM, n=11-18 mice/group). Compared with males, females with HT-MS gained less BW (14% vs. 22%, p<0.05), 2), had lower glucose levels (265±13 mg/dL vs 191±14 vs., p<0.001) and covered a greater distance on the treadmill (p<0.05). SBP and DBP was similary increased vs. their controls in both groups. In males but not in females with HT-MS both the LV septum and posterior wall were thicker vs controls (p< 0.001). Left atrium size increased 7.6% in females and 20% in males. In the myocardium, CR2+MHCII+ Mo increased by 58% only in males (p<0.001, F=11.7). The CCR2-MHCII- Mo increased by 75% in HT-MS females vs their controls, (p<0.001,F=18.7) and vs males. The CCR2-MHCII+ Mo decreased by 28.4% only in males (p<0.05, F=3.7). Conclusion: In females with HT-MS protective resident cardiac Mo increased significantly which was associated to less CRM and better exercise performance. Activation of resident cardiac Mo may be an important mechanism for prevention and treatment of CRM by HT and MS.

Single-cell transcriptomics reveals writers of RNA modification-mediated immune microenvironment and cardiac resident Macro-MYL2 macrophages in heart failure

BackgroundHeart 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.MethodsWe 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.ResultsSingle-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.ConclusionOur 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.

Lysozyme 1 Inflamed CCR2+ Macrophages Promote Obesity-Induced Cardiac Dysfunction.

Macrophages are key players in obesity-associated cardiovascular diseases, which are marked by inflammatory and immune alterations. However, the pathophysiological mechanisms underlying macrophage's role in obesity-induced cardiac inflammation are incompletely understood. Our study aimed to identify the key macrophage population involved in obesity-induced cardiac dysfunction and investigate the molecular mechanism that contributes to the inflammatory response. In this study, we used single-cell RNA-sequencing analysis of Cd45+CD11b+F4/80+ cardiac macrophages to explore the heterogeneity of cardiac macrophages. The CCR2+ (C-C chemokine receptor 2) macrophages were specifically removed by a dual recombinase approach, and the macrophage CCR2 was deleted to investigate their functions. We also performed cleavage under target and tagmentation analysis, chromatin immunoprecipitation-polymerase chain reaction, luciferase assay, and macrophage-specific lentivirus transfection to define the impact of lysozyme C in macrophages on obesity-induced inflammation. We find that the Ccr2 cluster undergoes a functional transition from homeostatic maintenance to proinflammation. Our data highlight specific changes in macrophage behavior during cardiac dysfunction under metabolic challenge. Consistently, inducible ablation of CCR2+CX3CR1+ macrophages or selective deletion of macrophage CCR2 prevents obesity-induced cardiac dysfunction. At the mechanistic level, we demonstrate that the obesity-induced functional shift of CCR2-expressing macrophages is mediated by the CCR2/activating transcription factor 3/lysozyme 1/NF-κB (nuclear factor kappa B) signaling. Finally, we uncover a noncanonical role for lysozyme 1 as a transcription activator, binding to the RelA promoter, driving NF-κB signaling, and strongly promoting inflammation and cardiac dysfunction in obesity. Our findings suggest that lysozyme 1 may represent a potential target for the diagnosis of obesity-induced inflammation and the treatment of obesity-induced heart disease.

Vitamin B-6 Prevents Heart Failure with Preserved Ejection Fraction Through Downstream of Kinase 3 in a Mouse Model

BackgroundThere is an urgent need to develop an efficient therapeutic strategy for heart failure with preserved ejection fraction (HFpEF), which is mediated by phenotypic changes in cardiac macrophages. We previously reported that vitamin B-6 inhibits macrophage-mediated inflammasome activation. ObjectivesWe sought to examine whether the prophylactic use of vitamin B-6 prevents HFpEF. MethodsHFpEF model was elicited by a combination of high-fat diet and Nω-nitro-l-arginine methyl ester supplement in mice. Cardiac function was assessed using conventional echocardiography and Doppler imaging. Immunohistochemistry and immunoblotting were used to detect changes in the macrophage phenotype and myocardial remodeling-related molecules. ResultsCo-administration of vitamin B-6 with HFpEF mice mitigated HFpEF phenotypes, including diastolic dysfunction, cardiac macrophage phenotypic shifts, fibrosis, and hypertrophy. Echocardiographic improvements were observed, with the E/E' ratio decreasing from 42.0 to 21.6 and the E/A ratio improving from 2.13 to 1.17. The exercise capacity also increased from 295.3 to 657.7 min. However, these beneficial effects were negated in downstream of kinase (DOK) 3-deficient mice. Mechanistically, vitamin B-6 increased DOK3 protein concentrations and inhibited macrophage phenotypic changes, which were abrogated by an AMP-activated protein kinase inhibitor. ConclusionsVitamin B-6 increases DOK3 signaling to lower risk of HFpEF by inhibiting phenotypic changes in cardiac macrophages.

Abstract Or112: Cardiac Macrophage are Key Immune Drivers of Cardiometabolic HFpEF

Heart failure with preserved ejection fraction (HFpEF) can develop with obesity, hyperinsulinemia, and glucose intolerance or type 2 diabetes, a phenogroup designated cardiometabolic HFpEF. While inflammation considered an important underlying mechanism, the role of innate immunity is poorly define. We investigated the role of macrophages in pathogenesis of cardiometabolic HFpEF. C57BL/6 mice were fed either high-fat diet (HFD, 45% kcal fat, 35% carbohydrate, 20% protein, 4.73 kcal/g) or control diet (CD, 10% kcal fat, 70% carbohydrate, 20% protein, 3.85 kcal/g) for 24-28 weeks. HFD mice exhibited significantly increased body weight (BW) at equivalent calorie consumption, increased white adipose tissue (WAT) mass, glucose intolerance, and hyperinsulinemia. HFD mice also exhibited HFpEF, evidenced by increased relative wall thickness (RWT), E/e’ ratio, LA area, LVEDP, and lung weight and decreased exercise tolerance with preserved EF. CD64 + MHCII + LyVE1 + CCR2 – resident and CD64 + MHCII + CCR2 + infiltrating macrophages expanded significantly in both cardiac and visceral fat tissue. To evaluate the role of macrophages in HFpEF, we used Macrophage Ablation Fas-Induced Apoptosis (MaFia) mice that allow for conditional depletion of mononuclear phagocytes with the Fas ligand dimerizer AP20187. AP20187 treatment after 24 weeks of HFD feeding in MaFia mice depleted macrophages and normalized BW, and reversed cardiac hypertrophy (decreased RWT, histological myocyte cross-sectional area [CSA]), and cardiac dysfunction (improved E/e’ ratio and global longitudinal strain [GLS]), as compared to vehicle-treated HFD-induced HFpEF MaFia mice. To establish sufficiency of cardiac macrophages, we FACS-sorted CD45 + CD64 + F4/80 + cardiac macrophages from HFD and CD mice, and adoptively transferred (10K cells/mouse) by intramyocardial injection into naïve recipient mice, with evaluation 4 w later. Mice with HFD-heart cardiac macrophage transfer evidenced significant increases in left atrial area (P=0.008, E/e’ ratio (P=0.016), cardiomyocyte CSA (P=0.015) and cardiac fibrosis (P<0.05), and reduced |GLS|, as compared to recipient mice with CD-heart cardiac macrophage transfer. There were no differences in body weight between the two groups. We conclude : cardiac macrophage expansion is central to the pathogenesis of cardiometabolic HFpEF, and are both necessary and sufficient for the cardiac phenotype. These results raise the potential for macrophage-targeted interventions to mitigate HFpEF.

Abstract Tu075: Cardiac macrophages expressing CD206 and IL-4Ra are required for adverse LV remodeling in HF

Cardiac macrophages significantly expand in chronic heart failure (HF). We tested the hypothesis that CD206 + macrophages expressing interleukin (IL)-4Ra in the failing heart are key drivers of left ventricular (LV) remodeling and ischemic cardiomyopathy. Cardiac macrophages were profiled using flow cytometry in adult male C57BL/6 (WT) mice following non-reperfused myocardial infarction (MI) to induce HF or sham operation. CD206 + macrophages progressively expanded in post-MI hearts during the progression of LV remodeling and comprised ~85% of macrophages at 8 w. These macrophages were exclusively proliferative and predominantly C-C motif chemokine receptor (CCR2) – and major histocompatibility complex (MHC)II hi in failing hearts, with the majority (92%) of CD206 + CCR2 – macrophages expressing LYVE-1, an embryonically-derived resident macrophage marker. Nearly half of cardiac CD206 + macrophages expressed IL-4Ra; the abundance of CD206 + IL-4Ra + directly correlated with LV dysfunction and fibrosis. Intramyocardial adoptive transfer of IL-4-polarized bone marrow derived CD206 + macrophages induced progressive LV dilation, dysfunction and fibrosis over 4 w in naïve recipient mice. To evaluate the role of CD206 + IL-4Ra + macrophages in LV remodeling, we used male and female LysM CreERT2 ;IL-4Ra F/F mice that allow for inducible myeloid-specific IL-4Ra gene deletion. Administration of tamoxifen from at 4 to 10 w post-MI (in established HF), effectively deleted IL-4Ra in cardiac macrophages and significantly reduced CD206 + macrophage abundance and proliferation in the remodeling heart. Myeloid-specific IL-4Ra deletion further prevented LV remodeling progression, improved fibrosis and neovascularization, and alleviated LV systolic dysfunction, while suppressing expansion of cardiac immune cells and blood Ly6C high monocytosis. We conclude that an expanded and proliferative population of CD206 + IL-4Ra + macrophages primarily derived from resident macrophages are key mediators of pathological LV remodeling and fibrosis. Inhibition of CD206 + macrophage IL-4Ra signaling may be a fruitful therapeutic approach to alleviate disease progression in HF.

RNF149 Destabilizes IFNGR1 in Macrophages to Favor Postinfarction Cardiac Repair.

Macrophage-driven inflammation critically involves in cardiac injury and repair following myocardial infarction (MI). However, the intrinsic mechanisms that halt the immune response of macrophages, which is critical to preserve homeostasis and effective infarct repair, remain to be fully defined. Here, we aimed to determine the ubiquitination-mediated regulatory effects on averting exaggerated inflammatory responses in cardiac macrophages. We used transcriptome analysis of mouse cardiac macrophages and bone marrow-derived macrophages to identify the E3 ubiquitin ligase RNF149 (ring finger protein 149) as a modulator of macrophage response to MI. Employing loss-of-function methodologies, bone marrow transplantation approaches, and adenovirus-mediated RNF149 overexpression in macrophages, we elucidated the functional role of RNF149 in MI. We explored the underlying mechanisms through flow cytometry, transcriptome analysis, immunoprecipitation/mass spectrometry analysis, and functional experiments. RNF149 expression was measured in the cardiac tissues of patients with acute MI and healthy controls. RNF149 was highly expressed in murine and human cardiac macrophages at the early phase of MI. Knockout of RNF149, transplantation of Rnf149-/- bone marrow, and bone marrow macrophage-specific RNF149-knockdown markedly exacerbated cardiac dysfunction in murine MI models. Conversely, overexpression of RNF149 in macrophages attenuated the ischemia-induced decline in cardiac contractile function. RNF149 deletion increased infiltration of proinflammatory monocytes/macrophages, accompanied by a hastened decline in reparative subsets, leading to aggravation of myocardial apoptosis and impairment of infarct healing. Our data revealed that RNF149 in infiltrated macrophages restricted inflammation by promoting ubiquitylation-dependent proteasomal degradation of IFNGR1 (interferon gamma receptor 1). Loss of IFNGR1 rescued deleterious effects of RNF149 deficiency on MI. We further demonstrated that STAT1 (signal transducer and activator of transcription 1) activation induced Rnf149 transcription, which, in turn, destabilized the IFNGR1 protein to counteract type-II IFN (interferon) signaling, creating a feedback control mechanism to fine-tune macrophage-driven inflammation. These findings highlight the significance of RNF149 as a molecular brake on macrophage response to MI and uncover a macrophage-intrinsic posttranslational mechanism essential for maintaining immune homeostasis and facilitating cardiac repair following MI.

Abstract Tu139: Ferroptotic Cardiomyocytes Support Angiogenesis in the Infarcted Myocardium

Introduction: Mammalian cardiomyocytes have a low turnover rate which is insufficient to repopulate the damaged myocardium after injury caused by myocardial infarction (MI). Previously, we reported that ferroptosis is the main mechanism of cardiomyocyte death in the infarcted neonatal heart. We hypothesized that ferroptotic cardiomyocytes play a beneficial role during the wound healing process. Aims: In this study, we aim to characterize the role of ferroptotic cardiomyocytes by investigating their influence on non-cardiomyocyte populations in the heart post-MI. Methods: Left anterior descending artery occlusion (LAD-O) was performed on wild type (C 5 7BL/6J x FVB) mice at P1. Ferroptosis inhibitor ferrostatin-1 (Fer-1) was delivered at a 2mg/kg dose via subcutaneous injection immediately following LAD-O procedure and again daily until P4. Histology and immunofluorescence were performed to assess myocardial regeneration. iPSC-derived cardiomyocytes (iCMs) were treated with Erastin, Staurosporine, or vehicle control to generate conditioned media. HUVECs were treated with iCM conditioned media for tube formation assays. Results: The infarcts of Fer-1 treated animals show decreased total macrophages from 5.5% to 0.16% (P < 0.05, N = 6 per group, S.E.M. = 1.2%) and those present were less polarized towards the M2 phenotype, decreased from 62.5% to 7.9% (N = 6 per group, P < 0.001, S.E.M. = 9.6%). This trend was confirmed via flow cytometry. The number of Emcn + cells in the infarct was significantly reduced in Fer-1 treated mice, decreasing from 17% to 10% (S.E.M. = 1.7%, N = 4 per group, P < 0.01). HUVECs treated with conditioned media generated by treating iPSC-derived cardiomyocytes with Staurosporine, but not Erastin or DMSO, showed reduced mesh area (fold change from 0.94 to.0 24, N = 5 per group, P < 0.01. S.EM. = .128). Other tube formation endpoints such as extremities, junctions, and branching followed this trend. Conclusions: Our analysis revealed that ferroptotic cardiomyocytes play a supportive role in the wound healing and tissue remodeling environment by directly supporting angiogenesis and polarizing the cardiac macrophages towards a more pro-angiogenic state.

ADAM8 deficiency in macrophages promotes cardiac repair after myocardial infarction via ANXA2-mTOR-autophagy pathway

IntroductionA disintegrin and metalloproteinase 8 (ADAM8), a crucial regulator in macrophages, is closely associated with cardiovascular disease progression. ObjectivesThis study aimed to explore how ADAM8 regulates macrophage function to inhibit cardiac repair after myocardial infarction (MI). MethodsMacrophage-specific ADAM8 knockout mice (ADAM8flox/flox, Lyz2-Cre, KO) and corresponding control mice (ADAM8flox/flox, Flox) were established using the CRISPR/Cas9 system. Bone marrow transplantation was performed, and macrophage-specific ADAM8-overexpressing adeno-associated virus (AAV6-CD68-Adam8) was produced. Finally, proteomics, RNA sequencing, and co-immunoprecipitation/mass spectrometry (COIP/MS) were used to explore the underlying mechanisms involved. ResultsADAM8 was highly expressed in the plasma of patients with acute myocardial infarction (AMI) and in cardiac macrophages derived from AMI mice. ADAM8 KO mice exhibited enhanced angiogenesis, suppressed inflammation, reduced cardiac fibrosis, and improved cardiac function during AMI, which were reversed by overexpressing macrophage-specific ADAM8 and intervention with the clinical anti-angiogenic biologic bevacizumab. Bone marrow transplantation experiments produced ADAM8 KO phenotypes. RNA sequencing showed that autophagy was activated in bone marrow-derived macrophages (BMDMs) with ADAM8 KO, which was confirmed via p-mTOR Ser2448/mTOR, p62, and LC3II/I detection. Autophagy inactivation suppressed angiogenic factor release and promoted inflammation in BMDMs with ADAM8 KO. Mechanistically, ADAM8 could bind to ANXA2 and promote phosphorylation of the ANXA2 Ser26 site. ADAM8 KO impeded ANXA2 phosphorylation, inhibited mTOR Ser2448 site phosphorylation, and activated autophagy, which were demonstrated using the activation or inactivation of ANXA2 phosphorylation. ConclusionsADAM8 was increased in cardiac macrophages after AMI. The ADAM8-ANXA2-mTOR-autophagy axis in macrophages is responsible for regulating angiogenesis and inflammation following MI. Thus, ADAM8 may be a new target in MI treatment.

Uncovering the connection between Ly6ChiCD103+ myeloid cells and radiation-induced cardiac fibrosis by CyTOF

Several immune cell populations participate in the development of radiation-induced cardiac fibrosis. However, the underlying mechanism remains to be elucidated. Male C57BL/6 mice (8–12 weeks old) were anesthetized and exposed to a single cardiac radiation dose of 20 Gy using the small-animal radiation research platform. We conducted echocardiography and histological analysis to identify cardiac fibrosis from a functional and pathological perspective. Time-of-flight mass cytometry (CyTOF) was used to describe the compositional changes of immune cells 1, 4, and 8 weeks after cardiac irradiation in mouse peripheral blood and cardiac tissue samples. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to measure CD14 and CD105 mRNA levels from peripheral blood cells in eight patients who received thoracic radiotherapy 6 months ago. We observed reduced cardiac systolic function and increased collagen deposition in cardiac tissue after irradiation. Transforming growth factor-β, tumor necrosis factor-α, and interleukin-6 expression significantly elevated in the plasma. We identified a significant increase in CD45+ immune cell levels four weeks after cardiac irradiation using CyTOF, and neutrophil, monocyte, and macrophage levels elevated in blood samples after cardiac irradiation (four weeks). In cardiac tissue samples, monocyte and macrophage levels increased after cardiac irradiation (four weeks) compared with control group. Macrophages and monocytes were further analyzed, and the proportion of Ly6ChiCD103+ myeloid cells increased after cardiac irradiation in tissue samples (four weeks). RT-qPCR revealed that CD14 expression was higher in patients with cardiac injured group than in the control group (Previous studies reported that Ly6Chi monocytes in mice are similar to CD14 + CD16− monocytes in humans). We found that Ly6ChiCD103+ myeloid cells are critical subsets in radiation-induced cardiac fibrosis and might play protective roles in the process. Ly6ChiCD103+ myeloid cells may be considered an early biomarker for detecting radiation-induced cardiac fibrosis.

Murine exosomal miR-30a aggravates cardiac function after acute myocardial infarction via regulating cell fate of cardiomyocytes and cardiac resident macrophages

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.

Unveiling the Potential of Migrasomes: A Machine-Learning-Driven Signature for Diagnosing Acute Myocardial Infarction.

Recent studies have demonstrated that the migrasome, a newly functional extracellular vesicle, is potentially significant in the occurrence, progression, and diagnosis of cardiovascular diseases. Nonetheless, its diagnostic significance and biological mechanism in acute myocardial infarction (AMI) have yet to be fully explored. To remedy this gap, we employed an integrative machine learning (ML) framework composed of 113 ML combinations within five independent AMI cohorts to establish a predictive migrasome-related signature (MS). To further elucidate the biological mechanism underlying MS, we implemented single-cell RNA sequencing (scRNA-seq) of cardiac Cd45+ cells from AMI-induced mice. Ultimately, we conducted mendelian randomization (MR) and molecular docking to unveil the therapeutic effectiveness of MS. MS demonstrated robust predictive performance and superior generalization, driven by the optimal combination of Stepglm and Lasso, on the expression of nine migrasome genes (BMP1, ITGB1, NDST1, TSPAN1, TSPAN18, TSPAN2, TSPAN4, TSPAN7, TSPAN9, and WNT8A). Notably, ITGB1 was found to be predominantly expressed in cardiac macrophages in AMI-induced mice, mechanically regulating macrophage transformation between anti-inflammatory and pro-inflammatory. Furthermore, we showed a positive causality between genetic predisposition towards ITGB1 expression and AMI risk, positioning it as a causative gene. Finally, we showed that ginsenoside Rh1, which interacts closely with ITGB1, could represent a novel therapeutic approach for repressing ITGB1. Our MS has implications in forecasting and curving AMI to inform future diagnostic and therapeutic strategies for AMI.

Excessive accumulation of epicardial adipose tissue promotes microvascular obstruction formation after myocardial ischemia/reperfusion through modulating macrophages polarization

BackgroundOwing to its unique location and multifaceted metabolic functions, epicardial adipose tissue (EAT) is gradually emerging as a new metabolic target for coronary artery disease risk stratification. Microvascular obstruction (MVO) has been recognized as an independent risk factor for unfavorable prognosis in acute myocardial infarction patients. However, the concrete role of EAT in the pathogenesis of MVO formation in individuals with ST-segment elevation myocardial infarction (STEMI) remains unclear. The objective of the study is to evaluate the correlation between EAT accumulation and MVO formation measured by cardiac magnetic resonance (CMR) in STEMI patients and clarify the underlying mechanisms involved in this relationship.MethodsFirstly, we utilized CMR technique to explore the association of EAT distribution and quantity with MVO formation in patients with STEMI. Then we utilized a mouse model with EAT depletion to explore how EAT affected MVO formation under the circumstances of myocardial ischemia/reperfusion (I/R) injury. We further investigated the immunomodulatory effect of EAT on macrophages through co-culture experiments. Finally, we searched for new therapeutic strategies targeting EAT to prevent MVO formation.ResultsThe increase of left atrioventricular EAT mass index was independently associated with MVO formation. We also found that increased circulating levels of DPP4 and high DPP4 activity seemed to be associated with EAT increase. EAT accumulation acted as a pro-inflammatory mediator boosting the transition of macrophages towards inflammatory phenotype in myocardial I/R injury through secreting inflammatory EVs. Furthermore, our study declared the potential therapeutic effects of GLP-1 receptor agonist and GLP-1/GLP-2 receptor dual agonist for MVO prevention were at least partially ascribed to its impact on EAT modulation.ConclusionsOur work for the first time demonstrated that excessive accumulation of EAT promoted MVO formation by promoting the polarization state of cardiac macrophages towards an inflammatory phenotype. Furthermore, this study identified a very promising therapeutic strategy, GLP-1/GLP-2 receptor dual agonist, targeting EAT for MVO prevention following myocardial I/R injury.

Interleukin-5 alleviates cardiac remodelling via the STAT3 pathway in angiotensin II-infused mice.

Interleukin-5 (IL-5) has been reported to be involved in cardiovascular diseases, such as atherosclerosis and cardiac injury. This study aimed to investigate the effects of IL-5 on cardiac remodelling. Mice were infused with angiotensin II (Ang II), and the expression and source of cardiac IL-5 were analysed. The results showed that cardiac IL-5 expression was time- and dose-dependently decreased after Ang II infusion, and was mainly derived from cardiac macrophages. Additionally, IL-5-knockout (IL-5-/-) mice were used to observe the effects of IL-5 knockout on Ang II-induced cardiac remodelling. We found knockout of IL-5 significantly increased the expression of cardiac hypertrophy markers, elevated myocardial cell cross-sectional areas and worsened cardiac dysfunction in Ang II-infused mice. IL-5 deletion also promoted M2 macrophage differentiation and exacerbated cardiac fibrosis. Furthermore, the effects of IL-5 deletion on cardiac remodelling was detected after the STAT3 pathway was inhibited by S31-201. The effects of IL-5 on cardiac remodelling and M2 macrophage differentiation were reversed by S31-201. Finally, the effects of IL-5 on macrophage differentiation and macrophage-related cardiac hypertrophy and fibrosis were analysed invitro. IL-5 knockout significantly increased the Ang II-induced mRNA expression of cardiac hypertrophy markers in myocardial cells that were co-cultured with macrophages, and this effect was reversed by S31-201. Similar trends in the mRNA levels of fibrosis markers were observed when cardiac fibroblasts and macrophages were co-cultured. In conclusions, IL-5 deficiency promote the differentiation of M2 macrophages by activating the STAT3 pathway, thereby exacerbating cardiac remodelling in Ang II-infused mice. IL-5 may be a potential target for the clinical prevention of cardiac remodelling.

Shenfu Injection regulates macrophage polarization via TLR4/NF-κB pathway to reduce inflammation in chronic heart failure

This study aimed to investigate the therapeutic effect of Shenfu Injection on mice with chronic heart failure(CHF) and its effect on macrophage polarization. C57BL/6J mice were randomly assigned to the normal and model groups. The CHF model was established by intraperitoneal injection of isoproterenol(ISO, 7.5 mg·kg~(-1), 28 d). The successful modeling was determined by asses-sing the cardiac function and N-terminal pro-brain natriuretic peptide(NT-proBNP). The modeled mice were randomly divided into the model group, Shenfu Injection group, and TAK-242 group, and were injected intraperitoneally with the corresponding drugs for 15 days. Cardiac function was evaluated using echocardiography. Hematoxylin-eosin(HE) staining was used to detect the pathomorphology. Enzyme-linked immunosorbent assay(ELISA) was used to detect the values of serum NT-proBNP, interleukin-6(IL-6), tumor necrosis factor-α(TNF-α), IL-10, and arginase 1(Arg-1). Flow cytometry was applied to detect the relative content and M1/M2 polarization of cardiac macrophages. Quantitative polymerase chain reaction(qPCR) and Western blot were used to detect the changes in the Toll-like receptor 4(TLR4)/nuclear factor-κB(NF-κB) pathway-related mRNA and protein expressions. Compared with the normal group, mice in the model group had lower values of left ventricular ejection fraction(LVEF) and left ventricular fractional shorte-ning(LVFS), higher values of left ventricular internal diastolic end-diastolic(LVIDd), left ventricular internal diastolic end-systolic(LVIDs), NT-proBNP, TNF-α, and IL-6(P<0.01); the number of macrophages increased in cardiac tissues(P<0.05), and the values of M1-F4/80~+CD86~+ were increased(P<0.01), while the values of M2-F4/80~+CD163~+ decreased(P<0.05); the mRNA and protein expressions of TLR4, myeloid differentiation factor 88(MyD88), IκB kinase α(IKKα), and NF-κB p65 in myocardial tissues were significantly elevated(P<0.05, P<0.01). Compared with the model group, mice in the Shenfu Injection and TAK-242 groups showed elevated LVEF, LVFS, IL-10, and Arg-1 levels, and decreased LVIDd, LVIDs, NT-proBNP, TNF-α, and IL-6 levels(P<0.05, P<0.01); the cardiac F4/80~+CD11b~+(macrophage) and M1-F4/80~+ CD86~+ values were significantly down-regulated, while M2-F4/80~+CD163~+ values were increased(P<0.05, P<0.01); and the mRNA and protein expressions of TLR4, MyD88, IKKα, and NF-κB p65 in myocardial tissues were notably decreased(P<0.05, P<0.01). CHF mice have an imbalance of M1/M2 macrophage polarization, with M1-type macrophages predominating. Shenfu Injection promotes macrophage polarization towards M2, inhibits M1-type macrophage activation, and attenuates inflammatory responses in heart failure by regulating the TLR4/NF-κB signaling pathway.

Primitive macrophages enable long-term vascularization of human heart-on-a-chip platforms

The intricate anatomical structure and high cellular density of the myocardium complicate the bioengineering of perfusable vascular networks within cardiac tissues. Invivo neonatal studies highlight the key role of resident cardiac macrophages in post-injury regeneration and angiogenesis. Here, we integrate human pluripotent stem-cell-derived primitive yolk-sac-like macrophages within vascularized heart-on-chip platforms. Macrophage incorporation profoundly impacted the functionality and perfusability of microvascularized cardiac tissues up to 2weeks of culture. Macrophages mitigated tissue cytotoxicity and the release of cell-free mitochondrial DNA (mtDNA), while upregulating the secretion of pro-angiogenic, matrix remodeling, and cardioprotective cytokines. Bulk RNA sequencing (RNA-seq) revealed an upregulation of cardiac maturation and angiogenesis genes. Further, single-nuclei RNA sequencing (snRNA-seq) and secretome data suggest that macrophages may prime stromal cells for vascular development by inducing insulin like growth factor binding protein 7 (IGFBP7) and hepatocyte growth factor (HGF) expression. Our results underscore the vital role of primitive macrophages in the long-term vascularization of cardiac tissues, offering insights for therapy and advancing heart-on-a-chip technologies.

Functional transformation of macrophage mitochondria in cardiovascular diseases.

Mitochondria are pivotal in the modulation of macrophage activation, differentiation, and survival. Furthermore, macrophages are instrumental in the onset and progression of cardiovascular diseases. Hence, it is imperative to investigate the role of mitochondria within macrophages in the context of cardiovascular disease. In this review, we provide an updated description of the origin and classification of cardiac macrophages and also focused on the relationship between macrophages and mitochondria in cardiovascular diseases with respect to (1) proinflammatory or anti-inflammatory macrophages, (2) macrophage apoptosis, (3) macrophage pyroptosis, and (4) macrophage efferocytosis. Clarifying the relationship between mitochondria and macrophages can aid the exploration of novel therapeutic strategies for cardiovascular disease.

Dissecting and Visualizing the Functional Diversity of Cardiac Macrophages

Cardiac macrophages represent a functionally diverse population of cells involved in cardiac homeostasis, repair, and remodeling. With recent advancements in single-cell technologies, it is possible to elucidate specific macrophage subsets based on transcriptional signatures and cell surface protein expression to gain a deep understanding of macrophage diversity in the heart. The use of fate-mapping technologies and parabiosis studies have provided insight into the ontogeny and dynamics of macrophages identifying subsets derived from embryonic and adult definitive hematopoietic progenitors that include tissue-resident and bone marrow monocyte-derived macrophages, respectively. Within the heart, these subsets have distinct tissue niches and functional roles in the setting of homeostasis and disease, with cardiac resident macrophages representing a protective cell population while bone marrow monocyte-derived cardiac macrophages have a context-dependent effect, triggering both proinflammatory tissue injury, but also promoting reparative functions. With the increased understanding of the clinical relevance of cardiac macrophage subsets, there has been an increasing need to detect and measure cardiac macrophage compositions in living animals and patients. New molecular tracers compatible with positron emission tomography/computerized tomography and positron emission tomography/ magnetic resonance imaging have enabled investigators to noninvasively and serially visualize cardiac macrophage subsets within the heart to define associations with disease and measure treatment responses. Today, advancements within this thriving field are poised to fuel an era of clinical translation.

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.