Myocardial infarction remodeling that progresses to heart failure: a signaling misunderstanding

Meteorin‑like/meteorin‑β protects against cardiac dysfunction after myocardial infarction in mice by inhibiting autophagy

Meteorin-β (Metrnβ) is a protein that is secreted by skeletal muscle and adipose tissue, and participates in cardiovascular diseases. However, its role in myocardial infarction (MI) has not been fully elucidated to date. The aim of the present study was to investigate the role and underlying mechanism of Metrnβ in MI. In the present study, mice were subjected to left coronary ligation to induce a MI model before being injected with adeno-associated virus 9 (AAV9)-Metrnβ to overexpress Metrnβ. Mice were subjected to echocardiography and pressure-volume measurements 2 weeks after ligation. Cardiac injury was measured from the levels of cardiac troponin T and pro-inflammatory factors, which were detected using ELISA kits. Cardiac remodelling was determined from the cross-sectional areas detected using H&E and wheat germ agglutinin staining as well as from the transcriptional levels of hypertrophic and fibrosis markers detected using reverse transcription-quantitative PCR. Cardiac function was detected using echocardiography and pressure-volume measurements. In addition, H9c2 cardiomyocytes were transfected with Ad-Metrnβ to overexpress Metrnβ, before being exposed to hypoxia to induce ischaemic injury. Apoptosis was determined using TUNEL staining and caspase 3 activity. Cell inflammation was detected using ELISA assays for pro-inflammatory factors. Autophagy was detected using LC3 staining and assessing the protein level of LC3II using western blotting. H9c2 cells were also treated with rapamycin to induce autophagy. It was revealed that Metrnβ expression was reduced in both mouse serum and heart tissue 2 weeks post-MI. Metrnβ overexpression using AAV9-Metrnβ delivery reduced the mortality rate, decreased the infarction size and reduced the extent of myocardial injury 2 weeks post-MI. Furthermore, Metrnβ overexpression inhibited cardiac hypertrophy, fibrosis and inflammation post-MI. In ischaemic H9c2 cells, Metrnβ overexpression using adenovirus also reduced cell injury, cell death and inflammatory response. Metrnβ overexpression suppressed MI-induced autophagy in vitro. Following autophagy activation using rapamycin in vitro, the protective effects induced by Metrnβ were reversed. Taken together, these results indicated that Metrnβ could protect against cardiac dysfunction post-MI in mice by inhibiting autophagy.

Proteomics of the heart

Mass spectrometry-based proteomics is a sophisticated identification tool specializing in portraying protein dynamics at a molecular level. Proteomics provides biologists with a snapshot of context-dependent protein and proteoform expression, structural conformations, dynamic turnover, and protein-protein interactions. Cardiac proteomics can offer a broader and deeper understanding of the molecular mechanisms that underscore cardiovascular disease, and it is foundational to the development of future therapeutic interventions. This review encapsulates the evolution, current technologies, and future perspectives of proteomic-based mass spectrometry as it applies to the study of the heart. Key technological advancements have allowed researchers to study proteomes at a single-cell level and employ robot-assisted automation systems for enhanced sample preparation techniques, and the increase in fidelity of the mass spectrometers has allowed for the unambiguous identification of numerous dynamic posttranslational modifications. Animal models of cardiovascular disease, ranging from early animal experiments to current sophisticated models of heart failure with preserved ejection fraction, have provided the tools to study a challenging organ in the laboratory. Further technological development will pave the way for the implementation of proteomics even closer within the clinical setting, allowing not only scientists but also patients to benefit from an understanding of protein interplay as it relates to cardiac disease physiology.

Fibroblasts and platelets: a face-to-face dialogue at the heart of cardiac fibrosis

Myocardial fibrosis is a feature found in most cardiac diseases and a key element contributing to heart failure and its progression. It has therefore become a subject of particular interest in cardiac research. Mechanisms leading to pathological cardiac remodeling and heart failure are diverse, including effects on cardiac fibroblasts, the main players in cardiac extracellular matrix synthesis, but also on cardiomyocytes, immune cells, endothelial cells, and more recently, platelets. Although transforming growth factor-β (TGF-β) is a primary regulator of fibrosis development, the cellular and molecular mechanisms that trigger its activation after cardiac injury remain poorly understood. Different types of anti-TGF-β drugs have been tested for the treatment of cardiac fibrosis and have been associated with side effects. Therefore, a better understanding of these mechanisms is of great clinical relevance and could allow us to identify new therapeutic targets. Interestingly, it has been shown that platelets infiltrate the myocardium at an early stage after cardiac injury, producing large amounts of cytokines and growth factors. These molecules can directly or indirectly regulate cells involved in the fibrotic response, including cardiac fibroblasts and immune cells. In particular, platelets are known to be a major source of TGF-β1. In this review, we have provided an overview of the classical cellular effectors involved in the pathogenesis of cardiac fibrosis, focusing on the emergent role of platelets, while discussing opportunities for novel therapeutic interventions.

Risk prediction model construction for asthma after allergic rhinitis by blood immune T effector cells

BACKGROUND

Allergic rhinitis (AR) and asthma (AS) are prevalent and frequently co-occurring respiratory diseases, with mutual influence on each other. They share similar etiology, pathogenesis, and pathological changes. Due to the anatomical continuity between the upper and lower respiratory tracts, allergic inflammation in the nasal cavity can readily propagate downwards, leading to bronchial inflammation and asthma. AR serves as a significant risk factor for AS by potentially inducing airway hyperresponsiveness in patients. Currently, there is a lack of reliable predictors for the progression from AR to AS.

METHODS

In this exhaustive investigation, we reexamined peripheral blood single cell RNA sequencing datasets from patients with AS following AR and healthy individuals. In addition, we used the bulk RNA sequencing dataset as a validation lineup, which included AS, AR, and healthy controls. Using marker genes of related cell subtype, signatures predicting the progression of AR to AS were generated.

RESULTS

We identified a subtype of immune-activating effector T cells that can distinguish patients with AS after AR. By combining specific marker genes of effector T cell subtype, we established prediction models of 16 markers. The model holds great promise for assessing AS risk in individuals with AR, providing innovative avenues for clinical diagnosis and treatment strategies.

CONCLUSION

Subcluster T effector cells may play a key role in post-AR AS. Notably, ACTR3 and HSPA8 genes were significantly upregulated in the blood of AS patients compared to healthy patients.

In-Hospital Levels of Circulating MicroRNAs as Potential Predictors of Left Ventricular Remodeling Post-Myocardial Infarction

Background and Objectives: Biochemical and molecular regulation of both adaptive and pathological responses of heart tissue to ischemic injury is widely investigated. However, it is still not fully understood. Several biomarkers are tested as predictors of left ventricle (LV) remodeling after myocardial infarction (MI). The aim of this study was to assess the relationship between selected microRNAs (miRNAs) and LV function and morphology in patients after MI. Materials and Methods: Selected miRNAs related to heart failure were assessed in the acute phase of MI: miR-150-3p, miR-21-5p, miR-19b-3p, miR-155-5p, miR-22-5p. Echocardiography with 3D imaging was performed at baseline and after 6 months. Remodeling was defined as >20% increase in LV end-diastolic volume, whereas reverse remodeling was defined as >10% reduction in LV end-systolic volume. Results: Eighty patients entered the registry. Remodeling occurred in 26% and reverse remodeling was reported in 51% of patients. In the presented study, none of the analyzed miRNAs were found to be a significant LV remodeling predictor. The observed correlations between miRNAs and other circulating biomarkers of myocardial remodeling were relatively weak. Conclusions: Our analysis does not demonstrate an association between the analyzed miRNAs and LV remodeling in patients with MI.

Fibroblast activation protein: Pivoting cancer/chemotherapeutic insight towards heart failure

An important mechanism for cancer progression is degradation of the extracellular matrix (ECM) which is accompanied by the emergence and proliferation of an activated fibroblast, termed the cancer associated fibroblast (CAF). More specifically, an enzyme pathway identified to be amplified with local cancer progression and proliferation of the CAF, is fibroblast activation protein (FAP). The development and progression of heart failure (HF) irrespective of the etiology is associated with left ventricular (LV) remodeling and changes in ECM structure and function. As with cancer, HF progression is associated with a change in LV myocardial fibroblast growth and function, and expresses a protein signature not dissimilar to the CAF. The overall goal of this review is to put forward the postulate that scientific discoveries regarding FAP in cancer as well as the development of specific chemotherapeutics could be pivoted to target the emergence of FAP in the activated fibroblast subtype and thus hold translationally relevant diagnostic and therapeutic targets in HF.

Tetrahydrocurcumin ameliorates postinfarction cardiac dysfunction and remodeling by inhibiting oxidative stress and preserving mitochondrial function via SIRT3 signaling pathway

BACKGROUND

Myocardial infarction (MI) often leads to sudden cardiac death. Persistent myocardial ischemia increases oxidative stress and impairs mitochondrial function, contributing significantly to postinfarction cardiac dysfunction and remodeling, and the subsequent progression to heart failure (HF). Tetrahydrocurcumin (THC), isolated from the rhizome of turmeric, has antioxidant properties and has been shown to protect against cardiovascular diseases. However, its effects on HF after MI are poorly understood.

PURPOSE

The objective was the investigation of the pharmacological effects of THC and its associated mechanisms in the pathogenesis of HF after MI.

METHODS

A total of 120 mice (C57BL/6, male) were used for the in vivo experiments. An MI mouse model was created by permanent ligation of the left anterior descending coronary artery. The mice received oral dose of THC at 120 mg/kg/d and the effects on MI-induced myocardial injury were evaluated by assessment of cardiac function, histopathology, myocardial oxidative levels, and mitochondrial function. Molecular mechanisms were investigated by intraperitoneal injection of 50 mg/kg of the SIRT3 selective inhibitor 3-TYP. Meanwhile, mouse neonatal cardiomyocytes were isolated and cultured in a hypoxic incubator to verify the effects of THC in vitro. Lastly, SIRT3 and Nrf2 were silenced using siRNAs to further explore the regulatory mechanism of key molecules in this process.

RESULTS

The mouse hearts showed significant impairment in systolic function after MI, together with enlarged infarct size, increased myocardial fibrosis, cardiac hypertrophy, and apoptosis of cardiomyocytes. A significant reversal of these changes was seen after treatment with THC. Moreover, THC markedly reduced reactive oxygen species generation and protected mitochondrial function, thus mitigating oxidative stress in the post-MI myocardium. Mechanistically, THC counteracted reduced Nrf2 nuclear accumulation and SIRT3 signaling in the MI mice while inhibition of Nrf2 or SIRT3 reversed the effects of THC. Cell experiments showed that Nrf2 silencing markedly reduced SIRT3 levels and deacetylation activity while inhibition of SIRT3 signaling had little impact on Nrf2 expression.

CONCLUSION

This is the first demonstration that THC protects against the effects of MI. THC reduced both oxidative stress and mitochondrial damage by regulating Nrf2-SIRT3 signaling. The results suggest the potential of THC in treating myocardial ischemic diseases.

Cardiac fibroblast GSK-3α aggravates ischemic cardiac injury by promoting fibrosis, inflammation, and impairing angiogenesis

Myocardial infarction (MI) is the leading cause of death worldwide. Glycogen synthase kinase-3 (GSK-3) has been considered to be a promising therapeutic target for cardiovascular diseases. GSK-3 is a family of ubiquitously expressed serine/threonine kinases. GSK-3 isoforms appear to play overlapping, unique, and even opposing functions in the heart. Previously, our group identified that cardiac fibroblast (FB) GSK-3β acts as a negative regulator of fibrotic remodeling in the ischemic heart. However, the role of FB-GSK-3α in MI pathology is not defined. To determine the role of FB-GSK-3α in MI-induced adverse cardiac remodeling, GSK-3α was deleted specifically in the residential fibroblast or myofibroblast (MyoFB) using tamoxifen (TAM) inducible Tcf21 or Periostin (Postn) promoter-driven Cre recombinase, respectively. Echocardiographic analysis revealed that FB- or MyoFB-specific GSK-3α deletion prevented the development of dilative remodeling and cardiac dysfunction. Morphometrics and histology studies confirmed improvement in capillary density and a remarkable reduction in hypertrophy and fibrosis in the KO group. We harvested the hearts at 4 weeks post-MI and analyzed signature genes of adverse remodeling. Specifically, qPCR analysis was performed to examine the gene panels of inflammation (TNFα, IL-6, IL-1β), fibrosis (COL1A1, COL3A1, COMP, Fibronectin-1, Latent TGF-β binding protein 2), and hypertrophy (ANP, BNP, MYH7). These molecular markers were essentially normalized due to FB-specific GSK-3α deletion. Further molecular studies confirmed that FB-GSK-3α could regulate NF-kB activation and expression of angiogenesis-related proteins. Our findings suggest that FB-GSK-3α plays a critical role in the pathological cardiac remodeling of ischemic hearts, therefore, it could be therapeutically targeted.

Development of Matrix Metalloproteinases-Mediated Extracellular Matrix Remodeling in Regenerative Medicine: A Mini Review

Extracellular matrix (ECM) components confer biomechanical properties, maintain cell phenotype and mediate tissue homeostasis. ECM remodeling is complex and plays a key role in both physiological and pathological processes. Matrix metalloproteinases (MMPs) are a group of enzymes responsible for ECM degradation and have been accepted as a key regulator in ECM remodeling. In this mini-review, we summarize MMPs categories, functions and the targeted substrates. We then discuss current understanding of the role of MMPs-mediated events, including inflammation reaction, angiogenesis, cellular activities, etc., in ECM remodeling in the context of regenerative medicine.

Adcy9 Gene Inactivation Improves Cardiac Function After Myocardial Infarction in Mice

BACKGROUND

Polymorphisms in the adenylate cyclase 9 (ADCY9) gene influence the benefits of the cholesteryl ester transfer protein (CETP) modulator dalcetrapib on cardiovascular events after acute coronary syndrome. We hypothesized that Adcy9 inactivation could improve cardiac function and remodelling following myocardial infarction (MI) in absence of CETP activity.

METHODS

Wild-type (WT) and Adcy9-inactivated (Adcy9Gt/Gt) male mice, transgenic or not for human CETP (tgCETP+/-), were subjected to MI by permanent left anterior descending coronary artery ligation and studied for 4 weeks. Left ventricular (LV) function was assessed by echocardiography at baseline, 1, and 4 weeks after MI. At sacrifice, blood, spleen and bone marrow cells were collected for flow cytometry analysis, and hearts were harvested for histologic analyses.

RESULTS

All mice developed LV hypertrophy, dilation, and systolic dysfunction, but Adcy9Gt/Gt mice exhibited reduced pathologic LV remodelling and better LV function compared with WT mice. There were no differences between tgCETP+/- and Adcy9Gt/Gt tgCETP+/- mice, which both exhibited intermediate responses. Histologic analyses showed smaller cardiomyocyte size, reduced infarct size, and preserved myocardial capillary density in the infarct border zone in Adcy9Gt/Gt vs WT mice. Count of bone marrow T cells and B cells were significantly increased in Adcy9Gt/Gt mice compared with the other genotypes.

CONCLUSIONS

Adcy9 inactivation reduced infarct size, pathologic remodelling, and cardiac dysfunction. These changes were accompanied by preserved myocardial capillary density and increased adaptive immune response. Most of the benefits of Adcy9 inactivation were only observed in the absence of CETP.

Risk prediction model construction for post myocardial infarction heart failure by blood immune B cells

Background

Myocardial infarction (MI) is a common cardiac condition with a high incidence of morbidity and mortality. Despite extensive medical treatment for MI, the development and outcomes of post-MI heart failure (HF) continue to be major factors contributing to poor post-MI prognosis. Currently, there are few predictors of post-MI heart failure.

Methods

In this study, we re-examined single-cell RNA sequencing and bulk RNA sequencing datasets derived from the peripheral blood samples of patients with myocardial infarction, including patients who developed heart failure and those who did not develop heart failure after myocardial infarction. Using marker genes of the relevant cell subtypes, a signature was generated and validated using relevant bulk datasets and human blood samples.

Results

We identified a subtype of immune-activated B cells that distinguished post-MI HF patients from non-HF patients. Polymerase chain reaction was used to confirm these findings in independent cohorts. By combining the specific marker genes of B cell subtypes, we developed a prediction model of 13 markers that can predict the risk of HF in patients after myocardial infarction, providing new ideas and tools for clinical diagnosis and treatment.

Conclusion

Sub-cluster B cells may play a significant role in post-MI HF. We found that the STING1, HSPB1, CCL5, ACTN1, and ITGB2 genes in patients with post-MI HF showed the same trend of increase as those without post-MI HF.

Temporal changes in glucose metabolism reflect polarization in resident and monocyte-derived macrophages after myocardial infarction

Introduction

Metabolic reprogramming from glycolysis to the mitochondrial tricarboxylic acid (TCA) cycle and oxidative phosphorylation may mediate macrophage polarization from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype. We hypothesized that changes in cardiac macrophage glucose metabolism would reflect polarization status after myocardial infarction (MI), ranging from the early inflammatory phase to the later wound healing phase.

Methods

MI was induced by permanent ligation of the left coronary artery in adult male C57BL/6J mice for 1 (D1), 3 (D3), or 7 (D7) days. Infarct macrophages were subjected to metabolic flux analysis or gene expression analysis. Monocyte versus resident cardiac macrophage metabolism was assessed using mice lacking the Ccr2 gene (CCR2 KO).

Results

By flow cytometry and RT-PCR, D1 macrophages exhibited an M1 phenotype while D7 macrophages exhibited an M2 phenotype. Macrophage glycolysis (extracellular acidification rate) was increased at D1 and D3, returning to basal levels at D7. Glucose oxidation (oxygen consumption rate) was decreased at D3, returning to basal levels at D7. At D1, glycolytic genes were elevated (Gapdh, Ldha, Pkm2), while TCA cycle genes were elevated at D3 (Idh1 and Idh2) and D7 (Pdha1, Idh1/2, Sdha/b). Surprisingly, Slc2a1 and Hk1/2 were increased at D7, as well as pentose phosphate pathway (PPP) genes (G6pdx, G6pd2, Pgd, Rpia, Taldo1), indicating increased PPP activity. Macrophages from CCR2 KO mice showed decreased glycolysis and increased glucose oxidation at D3, and decreases in Ldha and Pkm2 expression. Administration of dichloroacetate, a pyruvate dehydrogenase kinase inhibitor, robustly decreased pyruvate dehydrogenase phosphorylation in the non-infarcted remote zone, but did not affect macrophage phenotype or metabolism in the infarct zone.

Discussion

Our results indicate that changes in glucose metabolism and the PPP underlie macrophage polarization following MI, and that metabolic reprogramming is a key feature of monocyte-derived but not resident macrophages.

Construction of a web-based dynamic nomogram for predicting the prognosis in acute heart failure

AIMS

The early identification and appropriate management may provide clinically meaningful and substained benefits in patients with acute heart failure (AHF). This study aimed to develop an integrative nomogram with myocardial perfusion imaging (MPI) for predicting the risk of all-cause mortality in AHF patients.

METHODS AND RESULTS

Prospective study of 147 patients with AHF who received gated MPI (59.0 [47.5, 68.0] years; 78.2% males) were enrolled and followed for the primary endpoint of all-cause mortality. We analysed the demographic information, laboratory tests, electrocardiogram, and transthoracic echocardiogram by the least absolute shrinkage and selection operator (LASSO) regression for selection of key features. A multivariate stepwise Cox analysis was performed to identify independent risk factors and construct a nomogram. The predictive values of the constructed model were compared by Kaplan-Meier curve, area under the curves (AUCs), calibration plots, continuous net reclassification improvement, integrated discrimination improvement, and decision curve analysis. The 1, 3, and 5 year cumulative rates of death were 10%, 22%, and 29%, respectively. Diastolic blood pressure [hazard ratio (HR) 0.96, 95% confidence interval (CI) 0.93-0.99; P = 0.017], valvular heart disease (HR 3.05, 95% CI 1.36-6.83; P = 0.007), cardiac resynchronization therapy (HR 0.37, 95% CI 0.17-0.82; P = 0.014), N-terminal pro-B-type natriuretic peptide (per 100 pg/mL; HR 1.02, 95% CI 1.01-1.03; P < 0.001), and rest scar burden (HR 1.03, 95% CI 1.01-1.06; P = 0.008) were independent risk factors for patients with AHF. The cross-validated AUCs (95% CI) of nomogram constructed by diastolic blood pressure, valvular heart disease, cardiac resynchronization therapy, N-terminal pro-B-type natriuretic peptide, and rest scar burden were 0.88 (0.73-1.00), 0.83 (0.70-0.97), and 0.79 (0.62-0.95) at 1, 3, and 5 years, respectively. Continuous net reclassification improvement and integrated discrimination improvement were also observed, and the decision curve analysis identified the greater net benefit of the nomogram across a wide range of threshold probabilities (0-100% at 1 and 3 years; 0-61% and 62-100% at 5 years) compared with dismissing the included factors or using either factor alone.

CONCLUSIONS

A predictive nomogram for the risk of all-cause mortality in patients with AHF was developed and validated in this study. The nomogram incorporated the rest scar burden by MPI is highly predictive, and may help to better stratify clinical risk and guide treatment decisions in patients with AHF.

The Role of ncRNAs in Cardiac Infarction and Regeneration

Myocardial infarction is the most prevalent cardiovascular disease worldwide, and it is defined as cardiomyocyte cell death due to a lack of oxygen supply. Such a temporary absence of oxygen supply, or ischemia, leads to extensive cardiomyocyte cell death in the affected myocardium. Notably, reactive oxygen species are generated during the reperfusion process, driving a novel wave of cell death. Consequently, the inflammatory process starts, followed by fibrotic scar formation. Limiting inflammation and resolving the fibrotic scar are essential biological processes with respect to providing a favorable environment for cardiac regeneration that is only achieved in a limited number of species. Distinct inductive signals and transcriptional regulatory factors are key components that modulate cardiac injury and regeneration. Over the last decade, the impact of non-coding RNAs has begun to be addressed in many cellular and pathological processes including myocardial infarction and regeneration. Herein, we provide a state-of-the-art review of the current functional role of diverse non-coding RNAs, particularly microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), in different biological processes involved in cardiac injury as well as in distinct experimental models of cardiac regeneration.

Effect of Extracellular Matrix Stiffness on Candesartan Efficacy in Anti-Fibrosis and Antioxidation

Myocardial fibrosis progression and imbalanced redox state are closely associated with increased extracellular matrix (ECM) stiffness. Candesartan (CAN), an angiotensin II (Ang II) receptor inhibitor, has shown promising anti-fibrosis and antioxidant efficacy in previous cardiovascular disease studies. However, the effect of ECM stiffness on CAN efficacy remains elusive. In this study, we constructed rat models with three different degrees of myocardial fibrosis and treated them with CAN, and then characterized the stiffness, cardiac function, and NADPH oxidase-2 (NOX2) expression of the myocardial tissues. Based on the obtained stiffness of myocardial tissues, we used polyacrylamide (PA) gels with three different stiffness to mimic the ECM stiffness of cardiac fibroblasts (CFs) at the early, middle, and late stages of myocardial fibrosis as the cell culture substrates and then constructed CFs mechanical microenvironment models. We studied the effects of PA gel stiffness on the migration, proliferation, and activation of CFs without and with CAN treatment, and characterized the reactive oxygen species (ROS) and glutathione (GSH) levels of CFs using fluorometry and scanning electrochemical microscopy (SECM). We found that CAN has the best amelioration efficacy in the cardiac function and NOX2 levels in rats with medium-stiffness myocardial tissue, and the most obvious anti-fibrosis and antioxidant efficacy in CFs on the medium-stiffness PA gels. Our work proves the effect of ECM stiffness on CAN efficacy in myocardial anti-fibrosis and antioxidants for the first time, and the results demonstrate that the effect of ECM stiffness on drug efficacy should also be considered in the treatment of cardiovascular diseases.

The cardiac wound healing response to myocardial infarction

Myocardial infarction (MI) is defined as evidence of myocardial necrosis consistent with prolonged ischemia. In response to MI, the myocardium undergoes a series of wound healing events that initiate inflammation and shift to anti-inflammation before transitioning to tissue repair that culminates in scar formation to replace the region of the necrotic myocardium. The overall response to MI is determined by two major steps, the first of which is the secretion of proteases by infiltrating leukocytes to breakdown extracellular matrix (ECM) components, a necessary step to remove necrotic cardiomyocytes. The second step is the generation of new ECM that comprises the scar; and this step is governed by the cardiac fibroblasts as the major source of new ECM synthesis. The leukocyte component resides in the middle of the two-step process, contributing to both sides as the leukocytes transition from pro-inflammatory to anti-inflammatory and reparative cell phenotypes. The balance between the two steps determines the final quantity and quality of scar formed, which in turn contributes to chronic outcomes following MI, including the progression to heart failure. This review will summarize our current knowledge regarding the cardiac wound healing response to MI, primarily focused on experimental models of MI in mice. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology Immune System Diseases > Molecular and Cellular Physiology.

Hydrogen sulfide protects against ischemic heart failure by inhibiting RIP1/RIP3/MLKL-mediated necroptosis

The aim of the present study was to explore whether hydrogen sulfide (H2S) protects against ischemic heart failure (HF) by inhibiting the necroptosis pathway. Mice were randomized into Sham, myocardial infarction (MI), MI + propargylglycine (PAG) and MI + sodium hydrosulfide (NaHS) group, respectively. The MI model was induced by ligating the left anterior descending coronary artery. PAG was intraperitoneally administered at a dose of 50 mg/kg/day for 4 weeks, and NaHS at a dose of 4mg/kg/day for the same period. At 4 weeks after MI, the following were observed: A significant decrease in the cardiac function, as evidenced by a decline in ejection fraction (EF) and fractional shortening (FS); an increase in plasma myocardial injury markers, such as creatine kinase-MB (CK-MB) and cardiac troponin I (cTNI); an increase in myocardial collagen content in the heart tissues; and a decrease of H2S level in plasma and heart tissues. Furthermore, the expression levels of necroptosis-related markers such as receptor interacting protein kinase 1 (RIP1), RIP3 and mixed lineage kinase domain-like protein (MLKL) were upregulated after MI. NaHS treatment increased H2S levels in plasma and heart tissues, preserving the cardiac function by increasing EF and FS, decreasing plasma CK-MB and cTNI and reducing collagen content. Additionally, NaHS treatment significantly downregulated the RIP1/RIP3/MLKL pathway. While, PAG treatment aggravated cardiac function by activated the RIP1/RIP3/MLKL pathway. Overall, the present study concluded that H2S protected against ischemic HF by inhibiting RIP1/RIP3/MLKL-mediated necroptosis which could be a potential target treatment for ischemic HF.

Hydrogen sulfide protects against ischemic heart failure by inhibiting RIP1/RIP3/MLKL-mediated necroptosis

The aim of the present study was to explore whether hydrogen sulfide (H2S) protects against ischemic heart failure (HF) by inhibiting the necroptosis pathway. Mice were randomized into Sham, myocardial infarction (MI), MI + propargylglycine (PAG) and MI + sodium hydrosulfide (NaHS) group, respectively. The MI model was induced by ligating the left anterior descending coronary artery. PAG was intraperitoneally administered at a dose of 50 mg/kg/day for 4 weeks, and NaHS at a dose of 4 mg/kg/day for the same period. At 4 weeks after MI, the following were observed: A significant decrease in the cardiac function, as evidenced by a decline in ejection fraction (EF) and fractional shortening (FS); an increase in plasma myocardial injury markers, such as creatine kinase-MB (CK-MB) and cardiac troponin I (cTNI); an increase in myocardial collagen content in the heart tissues; and a decrease of H2S level in plasma and heart tissues. Furthermore, the expression levels of necroptosis-related markers such as receptor interacting protein kinase 1 (RIP1), RIP3 and mixed lineage kinase domain-like protein (MLKL) were upregulated after MI. NaHS treatment increased H2S levels in plasma and heart tissues, preserving the cardiac function by increasing EF and FS, decreasing plasma CK-MB and cTNI and reducing collagen content. Additionally, NaHS treatment significantly downregulated the RIP1/RIP3/MLKL pathway. While, PAG treatment aggravated cardiac function by activated the RIP1/RIP3/MLKL pathway. Overall, the present study concluded that H2S protected against ischemic HF by inhibiting RIP1/RIP3/MLKL-mediated necroptosis which could be a potential target treatment for ischemic HF.

LRRK2 deficiency protects the heart against myocardial infarction injury in mice via the P53/HMGB1 pathway

LRRK2 is a Ser/Thr kinase with multiple functional domains. Studies have shown that LRRK2 mutations are closely related to hereditary Parkinson's disease. However, its role in cardiovascular disease, especially in myocardial infarction, is unclear. The aim of this study was to explore the functional role of LRRK2 in myocardial infarction. Wild-type and LRRK2-knockout mice were subjected to coronary artery ligation (left anterior descending) to establish a myocardial infarction model. Neonatal rat cardiomyocytes were subjected to hypoxia to induce hypoxic injury in vitro. We found increased LRRK2 expression levels in the infarct periphery in mouse hearts and hypoxic cardiomyocytes. LRRK2-deficient mice exhibited decreased death rates and reduced infarction areas compared to wild-type controls 14 days after infarction. LRRK2-deficient mice showed reduced left ventricular fibrosis and inflammatory responses, as well as improved cardiac function. In the in vitro study, LRRK2 silencing decreased cleaved caspase-3 activity, reduced cardiomyocyte apoptosis, and diminished hypoxia-induced inflammation. However, LRRK2 overexpression enhanced cleaved caspase-3 activity, increased the number of apoptotic cardiomyocytes, and caused remarkable hypoxia-induced inflammation. When examining the underlying mechanisms, we found that hypoxia increased HIFα expression, which enhanced LRRK2 expression. LRRK2 induced high expression of HMGB1 via P53. When HMGB1 was blocked using an anti-HMGB1 antibody, the deleterious effects caused by LRRK2 overexpression following hypoxia were inhibited in cardiomyocytes. In summary, LRRK2 deficiency protects the heart against myocardial infarction injury. The mechanism underlying this effect involves the P53-HMGB1 pathway.

Therapeutics That Promote Sympathetic Reinnervation Modulate the Inflammatory Response After Myocardial Infarction

Myocardial infarction (MI) triggers an inflammatory response that transitions from pro-inflammatory to reparative over time. Restoring sympathetic nerves in the heart after MI prevents arrhythmias. This study investigated if reinnervation altered the immune response after MI. This study used quantitative multiplex immunohistochemistry to identify the immune cells present in the heart 2 weeks after ischemia-reperfusion. Two therapeutics stimulated reinnervation, preventing arrhythmias and shifting the immune response from inflammatory to reparative, with fewer pro-inflammatory macrophages and more regulatory T cells and reparative macrophages. Treatments did not alter macrophage phenotype in vitro, which suggested reinnervation contributed to the altered immune response.

Korotkoff sounds dynamically reflect changes in cardiac function based on deep learning methods

Korotkoff sounds (K-sounds) have been around for over 100 years and are considered the gold standard for blood pressure (BP) measurement. K-sounds are also unique for the diagnosis and treatment of cardiovascular diseases; however, their efficacy is limited. The incidences of heart failure (HF) are increasing, which necessitate the development of a rapid and convenient pre-hospital screening method. In this review, we propose a deep learning (DL) method and the possibility of using K-methods to predict cardiac function changes for the detection of cardiac dysfunctions.

Left Ventricular Remodeling after Myocardial Infarction: From Physiopathology to Treatment

Myocardial infarction (MI) is the leading cause of death and morbidity worldwide, with an incidence relatively high in developed countries and rapidly growing in developing countries. The most common cause of MI is the rupture of an atherosclerotic plaque with subsequent thrombotic occlusion in the coronary circulation. This causes cardiomyocyte death and myocardial necrosis, with subsequent inflammation and fibrosis. Current therapies aim to restore coronary flow by thrombus dissolution with pharmaceutical treatment and/or intravascular stent implantation and to counteract neurohormonal activation. Despite these therapies, the injury caused by myocardial ischemia leads to left ventricular remodeling; this process involves changes in cardiac geometry, dimension and function and eventually progression to heart failure (HF). This review describes the pathophysiological mechanism that leads to cardiac remodeling and the therapeutic strategies with a role in slowing the progression of remodeling and improving cardiac structure and function.

Plasma Exosome miRNAs Profile in Patients With ST-Segment Elevation Myocardial Infarction

Background

Circulating microRNAs (miRNAs) have been found to have different expressions in different phases of acute myocardial infarction. The profiles of plasma exosome miRNAs in patients with ST-segment elevation myocardial infarction (STEMI) at 3–6 months postinfarction are unknown.

Objective

The aim of this study was to assess the profiles of plasma exosome miRNAs in patients with STEMI in comparison with healthy volunteers and to select specific exosome miRNAs related to pathophysiological changes post-STEMI.

Methods

Plasma and echocardiography parameters were collected from 30 patients 3–6 months after STEMI and 30 healthy volunteers. Plasma exosome miRNAs were assessed by using high-throughput sequence (Illumina HiSeq 2500) and profile of the plasma exosome miRNAs was established in 10 patients and 6 healthy volunteers. The specific exosome miRNAs related to heart diseases were selected according to the TargetScan database. The specificity of the selected exosome miRNAs was evaluated in additional 20 post-STEMI patients and 24 healthy volunteers by using quantitative PCR (qPCR). Left ventricular remodeling (LVR) was defined using the European Association of Cardiovascular Imaging criteria according to echocardiography examination. Correlations between expression of the specific miRNAs and echocardiography parameters of LVR were assessed using the Spearman correlation analysis.

Results

Twenty eight upregulated miRNAs and 49 downregulated miRNAs were found in patients 3–6 months after STEMI (p &lt; 0.01) in comparison with the healthy volunteers. The two least expressed and heart-related exosome miRNAs were hsa-miR-181a-3p (0.64-fold, p &lt; 0.01) and hsa-miR-874-3p (0.50-fold, p &lt; 0.01), which were further confirmed by using qPCR and demonstrated significant specificity in another 20 patients with post-STEMI comparing to 24 healthy volunteers [area under the curve (AUC) = 0.68, p &lt; 0.05; AUC = 0.74, p &lt; 0.05]. The expression of hsa-miR-181a-3p was downregulated in patients with LV adverse remodeling in comparison with patients without LV adverse remodeling and healthy volunteers.

Conclusion

Circulating exosome miR-874-3p and miR-181a-3p were downregulated in patients with STEMI postinfarction. Exosome hsa-miR-181a-3p might play a potential role in the development of LVR in patients with post-STEMI.

Tanshinone IIA improves cardiac function via regulating miR-499-5p dependent angiogenesis in myocardial ischemic mice

BACKGROUND/AIMS

Myocardial ischemia-reperfusion injury leads to aggravated cardiac remodeling and heart failure. After myocardial infarction (MI), angiogenesis plays a vital role in the repair and regeneration of tissue. The purpose of the current study was to determine the effect of Tanshinone IIA (Tan IIA) on angiogenesis and elucidate its related mechanism.

METHODS

The C57BL/6 mice MI model was established to evaluate the therapeutic effect of Tan IIA in vivo. MicroRNA (miRNA) microarray and bioinformatics analysis were performed to determine the differential expressions of miRNAs after Tan IIA administration. Cell proliferation, migration, and angiogenesis capacity were detected by EdU, Transwell, and Tube formation assay in vitro, respectively. The relationship between miR-499-5p (miR-499) and paired phosphate and tension homolog deleted on chromosome ten (PTEN) was confirmed by using a Dual-luciferase reporter assay.

RESULTS

Our results showed that Tan IIA administration improved cardiac function after MI by activating angiogenesis. Further miRNA microarray and bioinformatics analysis revealed that miR-499 was significantly down-regulated, while PTEN was remarkably upregulated after Tan IIA administration post-MI. In addition, we found that miR-499 knock-down effectively promotes cell proliferation, migration, and tube formation ability of HUVECs. Dual-luciferase reporter assay demonstrated that PTEN contains a direct binding site for miR-499-5p.

CONCLUSION

Tan IIA improves cardiac function post-MI by inducing angiogenesis. In terms of the mechanism, Tan IIA promotes therapeutic angiogenesis by regulating miR-499-5p/PTEN signaling pathway.

Matrix metaloproteinases in vascular pathology

Vascular diseases are the main cause of morbidity and mortality. The vascular extracellular matrix (ECM) is essential in mechanical support, also regulating the cellular behavior fundamental to vascular function and homeostasis. Vascular remodeling is an adaptive response to various physiological and pathological changes and is associated with aging and vascular diseases. The aim of this review is provide a general overview of the involvement of MMPs in the pathogenesis of vascular diseases, namely, arterial hypertension, atherosclerosis, aortic aneurysms and myocardial infarction. The change in the composition of the ECM by matrix metalloproteinases (MMPs) generates a pro-inflammatory microenvironment that modifies the phenotypes of endothelial cells and vascular smooth muscle cells. They play a central role in morphogenesis, tissue repair and remodeling in response to injury, e.g., after myocardial infarction, and in progression of diseases such as atherosclerosis. Alterations in specific MMPs could influence arterial remodeling and lead to various pathological disorders such as hypertension and aneurysm formation. MMPs are regulated by endogenous tissue inhibitors of metalloproteinases (TIMPs), and the MMP/TIMP ratio generally determines the extent of ECM protein degradation and tissue remodeling. Studies are currently focused on improving the diagnostic and prognostic value of MMPs involved in the pathogenic process, increasing their therapeutic potential, and monitoring the disease. New selective MMP inhibitors may improve the specificity of these inhibitors, target specific MMPs in relevant pathological conditions and mitigate some of the side effects.

Short-Term Blockade of Pro-Inflammatory Alarmin S100A9 Favorably Modulates Left Ventricle Proteome and Related Signaling Pathways Involved in Post-Myocardial Infarction Recovery

Prognosis after myocardial infarction (MI) varies greatly depending on the extent of damaged area and the management of biological processes during recovery. Reportedly, the inhibition of the pro-inflammatory S100A9 reduces myocardial damage after MI. We hypothesize that a S100A9 blockade induces changes of major signaling pathways implicated in post-MI healing. Mass spectrometry-based proteomics and gene analyses of infarcted mice left ventricle were performed. The S100A9 blocker (ABR-23890) was given for 3 days after coronary ligation. At 3 and 7 days post-MI, ventricle samples were analyzed versus control and Sham-operated mice. Blockade of S100A9 modulated the expressed proteins involved in five biological processes: leukocyte cell–cell adhesion, regulation of the muscle cell apoptotic process, regulation of the intrinsic apoptotic signaling pathway, sarcomere organization and cardiac muscle hypertrophy. The blocker induced regulation of 36 proteins interacting with or targeted by the cellular tumor antigen p53, prevented myocardial compensatory hypertrophy, and reduced cardiac markers of post-ischemic stress. The blockade effect was prominent at day 7 post-MI when the quantitative features of the ventricle proteome were closer to controls. Blockade of S100A9 restores key biological processes altered post-MI. These processes could be valuable new pharmacological targets for the treatment of ischemic heart. Mass spectrometry data are available via ProteomeXchange with identifier PXD033683.

Temporal Changes in Pollen Concentration Predict Short-Term Clinical Outcomes in Acute Coronary Syndromes

Background Atmospheric changes in pollen concentration may affect human health by triggering various allergic processes. We sought to assess if changes in pollen concentrations were associated with different acute coronary syndrome (ACS) subtype presentations and short-term clinical outcomes. Methods and Results We analyzed data in consecutive patients presenting with ACS (unstable angina, non-ST-segment-elevation myocardial infarction, and ST-segment-elevation myocardial infarction) treated with percutaneous coronary intervention between January 2014 and December 2017 and enrolled in the VCOR (Victorian Cardiac Outcomes Registry). Baseline characteristics were compared among patients exposed to different grass and total pollen concentrations. The primary outcome was occurrence of ACS subtypes and 30-day major adverse cardiac and cerebrovascular events (composite of mortality, myocardial infarction, stent thrombosis, target vessel revascularization, or stroke). Of 15 379 patients, 7122 (46.3%) presented with ST-segment-elevation myocardial infarction, 6781 (44.1%) with non-ST-segment-elevation myocardial infarction, and 1476 (9.6%) with unstable angina. The mean age was 62.5 years, with men comprising 76% of patients. No association was observed between daily or seasonal grass and total pollen concentrations with the frequency of ACS subtype presentation. However, grass and total pollen concentrations in the preceding days (2-day average for grass pollen and 7-day average for total pollen) correlated with in-hospital mortality (odds ratio [OR], 2.17 [95% CI, 1.12-4.21]; P=0.021 and OR, 2.78 [95% CI, 1.00-7.74]; P=0.05), respectively, with a trend of 2-day grass pollen for 30-day major adverse cardiac and cerebrovascular events (OR, 1.50 [95% CI, 0.97-2.32]; P=0.066). Conclusions Increased pollen concentrations were not associated with differential ACS subtype presentation but were significantly related to in-hospital mortality following percutaneous coronary intervention, underscoring a potential biologic link between pollen exposure and clinical outcomes.

Evaluation of the right atrial phasic functions in patients with anterior ST-elevation myocardial infarction: a 2D speckle-tracking echocardiography study

Background

Evidence suggests that changes in left ventricular systolic and diastolic functions may affect right atrial (RA) phasic functions. We aimed to evaluate RA phasic functions in the presence of anterior ST-elevation myocardial infarction (ASTEMI) as an acute event and to compare the findings with those in a control group.

Methods

We recruited 92 consecutive ASTEMI patients without accompanying significant stenosis in the proximal and middle parts of the right coronary artery and 31 control subjects, matched for age, sex, diabetes, and hypertension. RA phasic functions were evaluated concerning their longitudinal 2D speckle-tracking echocardiography-derived markers. The ASTEMI group was followed up for all-cause mortality or reinfarction.

Results

In the ASTEMI group, RA strain was reduced during the reservoir (33.2% ± 4.3% vs 30.5% ± 8.1%; P = 0.021) and conduit (16% [12–18%] vs 14% [9–17%]; P = 0.048) phases. The other longitudinal 2D speckle-tracking echocardiography-derived markers of RA phasic functions were not different between the 2 groups. RA strain and strain rate during the contraction phase were predictive of all-cause mortality or reinfarction (hazard ratio = 0.80; P = 0.024 and hazard ratio = 0.39; P = 0.026, respectively).

Conclusions

Based on 2D speckle-tracking echocardiography, in the ASTEMI group, compared with the control group, RA reservoir and conduit functions were reduced, while RA contraction function was preserved. RA contraction function was predictive of all-cause mortality or reinfarction during the follow-up period.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02546-4.

Fibroblast mechanotransduction network predicts targets for mechano-adaptive infarct therapies

Regional control of fibrosis after myocardial infarction is critical for maintaining structural integrity in the infarct while preventing collagen accumulation in non-infarcted areas. Cardiac fibroblasts modulate matrix turnover in response to biochemical and biomechanical cues, but the complex interactions between signaling pathways confound efforts to develop therapies for regional scar formation. We employed a logic-based ordinary differential equation model of fibroblast mechano-chemo signal transduction to predict matrix protein expression in response to canonical biochemical stimuli and mechanical tension. Functional analysis of mechano-chemo interactions showed extensive pathway crosstalk with tension amplifying, dampening, or reversing responses to biochemical stimuli. Comprehensive drug target screens identified 13 mechano-adaptive therapies that promote matrix accumulation in regions where it is needed and reduce matrix levels in regions where it is not needed. Our predictions suggest that mechano-chemo interactions likely mediate cell behavior across many tissues and demonstrate the utility of multi-pathway signaling networks in discovering therapies for context-specific disease states.

Monomeric CRP Aggravates Myocardial Injury After Myocardial Infarction by Polarizing the Macrophage to Pro-Inflammatory Phenotype Through JNK Signaling Pathway

Objective

A polarized macrophage response plays a critical role in the pathophysiological process of myocardial infarction (MI). Several studies have shown a pro-inflammatory role for monomeric C-reactive protein (mCRP) in cardiovascular disease. However, the mechanism of how mCRP regulates macrophage phenotype switching remains unknown. In the present study, the effect of mCRP on macrophage polarization and its pathological function in myocardial repair after myocardial infarction was investigated.

Methods

MI was induced by permanent ligation of the left anterior descending coronary artery in ICR mice. Adult mice were injected with mCRP (2.5 mg/kg) with or without SP600125 (15 mg/kg, JNK inhibitor) 45 min before MI. The cardiac function, scar size as well as cardiac fibrosis, infiltration of inflammatory cells, and the level of proteins in the JNK signaling pathway in infarcted myocardium were assessed. In addition, the phenotypic characterization of macrophages was further measured by ELISA, flow cytometry and quantitative RT-PCR in cultured THP-1 cells or peritoneal macrophages.

Results

Cardiac function deterioration, ventricular dilatation and fibrosis were exacerbated in mice pretreatment with mCRP following MI. Meanwhile, an increased accumulation of infiltrated inflammatory cells in infarcted myocardium was observed in the mCRP group. Moreover, activation of the JNK signaling pathway was markedly elevated in mCRP treated animals post-MI. In contrast, pharmacological inhibition of JNK phosphorylation activity by SP600125 muted the detrimental effects of mCRP in MI mice. Furthermore, in vitro and in vivo co-culture experiments showed that mCRP shifted macrophage polarization towards pro-inflammatory phenotypes, and this polarization could be abolished by sp600125.

Conclusion

Taken together, our results imply that mCRP impairs myocardial repair after myocardial infarction by polarizing the macrophages into the pro-inflammatory M1 phenotype via the JNK-dependent pathway.

microRNA-17-5p downregulation inhibits autophagy and myocardial remodelling after myocardial infarction by targeting STAT3

MicroRNAs (miRs) are reported to regulate myocardial infarction (MI). This study was performed to investigate the function and mechanism of miR-17-5p in myocardial remodelling after MI. Initially, a mouse model of MI was established and MI mice were infected with lentivirus antago-miR-17-5p vector. High expression of miR-17-5p was found in myocardial tissues after MI. After inhibiting miR-17-5p expression, myocardial fibrosis, scarring, and cardiomyocyte apoptosis were improved, LC3-II/LC3-I ratio and Beclin-1 expression were decreased but p62 expression was increased. The dual-luciferase assay suggested that miR-17-5p targeted STAT3 and negatively regulated its expression. Then, after inhibiting STAT3 expression using STAT3 inhibitor S31-201, the fibrosis, scarring, and cardiomyocyte apoptosis were deteriorated, along with the rise of LC3-II/LC3-I and Beclin-1 expression, the reduction of p62 expression and the reversion of MI attenuation. In conclusion, inhibition of miR-17-5p can inhibit myocardial autophagy through targeting STAT3 and then inhibit myocardial remodelling, thereby protecting the myocardium after MI.

The benefits of sacubitril-valsartan in patients with acute myocardial infarction: a systematic review and meta-analysis

AIMS

We aimed to investigate whether sacubitril-valsartan could further improve the prognosis, cardiac function, and left ventricular (LV) remodelling in patients following acute myocardial infarction (AMI).

METHODS AND RESULTS

We searched the PubMed, Embase, Cochrane Library, and China National Knowledge Infrastructure (CNKI) from inception to 10 May 2021 to identify potential articles. Randomized controlled trials (RCTs) meeting the inclusion criteria were included and analysed. Thirteen RCTs, covering 1358 patients, were analysed. Compared with angiotensin-converting enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB), sacubitril-valsartan did not significantly reduced the cardiovascular mortality [risk ratio (RR) 0.65, 95% confidence interval (CI) 0.22 to 1.93, P = 0.434] and the rate of myocardial reinfarction (RR 0.65, 95% CI 0.29 to 1.46, P = 0.295) of patients following AMI, but the rate of hospitalization for heart failure (HF) (RR 0.48, 95% CI 0.35 to 0.66, P < 0.001) and the change of LV ejection fraction (LVEF) [weighted mean difference (WMD) 5.49, 95% CI 3.62 to 7.36, P < 0.001] were obviously improved. The N-terminal pro-brain natriuretic peptide (NT-ProBNP) level (WMD -310.23, 95% CI -385.89 to -234.57, P < 0.001) and the LV end-diastolic dimension (LVEDD) (WMD -3.16, 95% CI -4.59 to -1.73, P < 0.001) were also significantly lower in sacubitril-valsartan group than in ACEI/ARB group. Regarding safety, sacubitril-valsartan did not increase the risk of hypotension, hyperkalaemia, angioedema, and cough.

CONCLUSIONS

This meta-analysis suggests that early administration of sacubitril-valsartan may be superior to conventional ACEI/ARB to decrease the risk of hospitalization for HF, improve the cardiac function, and reverse the LV remodelling in patients following AMI.

Relationship Between the Eosinophil/Monocyte Ratio and Prognosis in Decompensated Heart Failure: A Retrospective Study

Purpose

The aim of this study was to assess the value of the eosinophil/monocyte ratio (EMR) for predicting the prognosis of decompensated heart failure (HF).

Patients and Methods

This was a retrospective cohort study. We included adults (≥18 years old) diagnosed with decompensated HF for whom EMR data were available. The patients were divided into three groups according to EMR tertiles (T1 [EMR≤0.15], T2 [0.15<EMR≤0.32], and T3 [EMR>0.32]). The primary endpoint was the composite outcome of cardiovascular death or HF rehospitalization.

Results

Initially, the records of 2264 patients with decompensated HF were screened; 1883 of these patients had EMR data and were therefore included in the study. There were 627 patients in the T1 group, 628 in the T2 group, and 628 in the T3 group. The risk of cardiovascular death or HF rehospitalization was significantly different among the three groups (Log rank test, P=0.007). Compared with the T3 group, both the T1 group (hazard ratio [HR]: 1.50, 95% confidence interval [CI]: 1.16–1.94, P=0.002) and the T2 group (HR: 1.34, 95% CI: 1.03–1.74, P=0.030) had significantly higher rates of cardiovascular death or HF rehospitalization. A Cochran-Armitage test for trend showed a positive correlation between the EMR and the composite outcome of cardiovascular death or HF. There was a significant difference between the three groups in terms of cardiovascular death (Log rank test, P<0.001) and HF rehospitalization (Log rank test, P=0.03).

Conclusion

The EMR is positively correlated with the risk of cardiovascular death or HF rehospitalization in patients with decompensated HF. Specifically, the lower the EMR, the higher the risk of cardiovascular death or HF rehospitalization.

Remodeling of Cardiac Gap Junctional Cell-Cell Coupling

The heart works as a functional syncytium, which is realized via cell-cell coupling maintained by gap junction channels. These channels connect two adjacent cells, so that action potentials can be transferred. Each cell contributes a hexameric hemichannel (=connexon), formed by protein subuntis named connexins. These hemichannels dock to each other and form the gap junction channel. This channel works as a low ohmic resistor also allowing the passage of small molecules up to 1000 Dalton. Connexins are a protein family comprising of 21 isoforms in humans. In the heart, the main isoforms are Cx43 (the 43 kDa connexin; ubiquitous), Cx40 (mostly in atrium and specific conduction system), and Cx45 (in early developmental states, in the conduction system, and between fibroblasts and cardiomyocytes). These gap junction channels are mainly located at the polar region of the cardiomyocytes and thus contribute to the anisotropic pattern of cardiac electrical conductivity. While in the beginning the cell–cell coupling was considered to be static, similar to an anatomically defined structure, we have learned in the past decades that gap junctions are also subject to cardiac remodeling processes in cardiac disease such as atrial fibrillation, myocardial infarction, or cardiomyopathy. The underlying remodeling processes include the modulation of connexin expression by e.g., angiotensin, endothelin, or catecholamines, as well as the modulation of the localization of the gap junctions e.g., by the direction and strength of local mechanical forces. A reduction in connexin expression can result in a reduced conduction velocity. The alteration of gap junction localization has been shown to result in altered pathways of conduction and altered anisotropy. In particular, it can produce or contribute to non-uniformity of anisotropy, and thereby can pre-form an arrhythmogenic substrate. Interestingly, these remodeling processes seem to be susceptible to certain pharmacological treatment.

Dimethyl fumarate preserves left ventricular infarct integrity following myocardial infarction via modulation of cardiac macrophage and fibroblast oxidative metabolism

Myocardial infarction (MI) is one of the leading causes of mortality and cardiovascular disease worldwide. MI is characterized by a substantial inflammatory response in the infarcted left ventricle (LV), followed by transition of quiescent fibroblasts to active myofibroblasts, which deposit collagen to form the reparative scar. Metabolic shifting between glycolysis and mitochondrial oxidative phosphorylation (OXPHOS) is an important mechanism by which these cell types transition towards reparative phenotypes. Thus, we hypothesized that dimethyl fumarate (DMF), a clinically approved anti-inflammatory agent with metabolic actions, would improve post-MI remodeling via modulation of macrophage and fibroblast metabolism. Adult male C57BL/6J mice were treated with DMF (10 mg/kg) for 3-7 days after MI. DMF attenuated LV infarct and non-infarct wall thinning at 3 and 7 days post-MI, and decreased LV dilation and pulmonary congestion at day 7. DMF improved LV infarct collagen deposition, myofibroblast activation, and angiogenesis at day 7. DMF also decreased pro-inflammatory cytokine expression (Tnf) 3 days after MI, and decreased inflammatory markers in macrophages isolated from the infarcted heart (Hif1a, Il1b). In fibroblasts extracted from the infarcted heart at day 3, RNA-Seq analysis demonstrated that DMF promoted an anti-inflammatory/pro-reparative phenotype. By Seahorse analysis, DMF did not affect glycolysis in either macrophages or fibroblasts at day 3, but enhanced macrophage OXPHOS while impairing fibroblast OXPHOS. Our results indicate that DMF differentially affects macrophage and fibroblast metabolism, and promotes anti-inflammatory/pro-reparative actions. In conclusion, targeting cellular metabolism in the infarcted heart may be a promising therapeutic strategy.

Preclinical rodent models of cardiac fibrosis

Cardiac fibrosis (scarring), characterised by an increased deposition of extracellular matrix (ECM) proteins, is a hallmark of most types of cardiovascular disease and plays an essential role in heart failure progression. Inhibition of cardiac fibrosis could improve outcomes in patients with cardiovascular diseases and particularly heart failure. However, pharmacological treatment of the ECM build-up is still lacking. In this context, preclinical models of heart disease are important tools for understanding the complex pathogenesis involved in the development of cardiac fibrosis which in turn could identify new therapeutic targets and the facilitation of antifibrotic drug discovery. Many preclinical models have been used to study cardiac fibrosis and each model provides mechanistic insights into the many factors that contribute to cardiac fibrosis. This review discusses the most frequently used rodent models of cardiac fibrosis and also provides context for the use of particular models of heart failure.

CTRP1 Aggravates Cardiac Dysfunction Post Myocardial Infarction by Modulating TLR4 in Macrophages

CTRP1 (C1q/TNF-α [tumour necrosis factor-α]-related protein 1), an adiponectin paralog, is associated with diabetes and adverse events in cardiovascular disease. However, its effect on cardiac function post myocardial infarction (MI) is unclear. Our study aimed to explore the role of CTRP1 in cardiac function post MI. CTRP1 global knockout mice were subjected to left anterior descending ligation to establish the MI model. C57BL6J mice were also administered recombinant CTRP1 protein (200 μg/kg) 7 days post MI. As a result, mice with CTRP1 deficiency exhibited an increased survival rate, a reduced infarct area, improved cardiac function and decreased inflammation and oxidative stress levels at 4 weeks post MI compared with those of mice receiving the CRTP1 injection, whose conditions deteriorated. However, cardiomyocytes with either CTRP1 silencing or CTRP1 treatment showed few differences in inflammation and oxidative stress levels compared with those of the control under hypoxic conditions. The activation of macrophages isolated from CTRP1-deficient mice was decreased in response to interferon-γ, while CTRP1 enhanced the activation of macrophages in response to interferon-γ. Macrophage scavengers and clodronate liposomes antagonized the effects of CTRP1 injection in mice. We also found that CTRP1 regulated macrophage activation via adiponectin receptor 1, which binds to TLR4 on the macrophage membrane. TLR4 knockout also antagonized the effects of the CTRP1 protein on mice with MI. Taken together, these data indicate that CTRP1 supresses cardiac function post MI via TLR4 on macrophages. Targeting CTRP1 may become a promising therapeutic approach to cardiac dysfunction post MI.

Stem cell therapy for heart failure: Medical breakthrough, or dead end?

Heart failure continues to be one of the leading causes of morbidity and mortality worldwide. Myocardial infarction is the primary causative agent of chronic heart failure resulting in cardiomyocyte necrosis and the subsequent formation of fibrotic scar tissue. Current pharmacological and non-pharmacological therapies focus on managing symptoms of heart failure yet remain unable to reverse the underlying pathology. Heart transplantation usually cannot be relied on, as there is a major discrepancy between the availability of donors and recipients. As a result, heart failure carries a poor prognosis and high mortality rate. As the heart lacks significant endogenous regeneration potential, novel therapeutic approaches have incorporated the use of stem cells as a vehicle to treat heart failure as they possess the ability to self-renew and differentiate into multiple cell lineages and tissues. This review will discuss past, present, and future clinical trials, factors that influence stem cell therapy outcomes as well as ethical and safety considerations. Preclinical and clinical studies have shown a wide spectrum of outcomes when applying stem cells to improve cardiac function. This may reflect the infancy of clinical trials and the limited knowledge on the optimal cell type, dosing, route of administration, patient parameters and other important variables that contribute to successful stem cell therapy. Nonetheless, the field of stem cell therapeutics continues to advance at an unprecedented pace. We remain cautiously optimistic that stem cells will play a role in heart failure management in years to come.

CircRNA 010567 plays a significant role in myocardial infarction via the regulation of the miRNA-141/DAPK1 axis

Background

Myocardial infarction (MI), caused by temporary or permanent coronary artery occlusion, poses a serious threat to patients’ lives. Circular RNAs (circRNAs), a new kind of endogenous noncoding RNAs, have been widely studied recently. This study was designed to illustrate and potential molecular mechanisms of circRNA 010567 in hypoxia-induced cardiomyocyte injury in vitro, so as to provide new strategies for the therapy of MI.

Methods

H9c2 cells were cultured in anoxic conditions with 94% N₂, 5% CO₂, and 1% O₂ to establish the in vitro MI model. Cell viability and apoptosis were checked using MTT and flow cytometry assay, respectively, Moreover, the levels of circRNA 010567, miR-141, and DAPK1 was determined using qRT-PCR. The putative targets of circRNA 010567 and miR-141 were confirmed by dual-luciferase reporter system and the RNA immunoprecipitation (RIP) assay. The release of creatine kinase-MB (CK-MB), cardiac troponin I (cTnI), and the viability of mitochondria were detected using assay kits.

Results

The current study revealed that circRNA 010567 and DAPK1 were over-expressed, and miR-141 was low-expressed in hypoxia-induced MI. circRNA 010567 sponges miR-141 and DAPK1 was a direct target of miR-141. Mechanistic investigations revealed that circRNA 010567-siRNA impaired the release of CK-MB and cTnI, and promoted the viability of mitochondria in hypoxia-induced H9c2 cells, while these findings were reversed by the miR-141 inhibitor. In addition, the miR-141 mimic markedly reduced the release of CK-MB and cTnI, and promoted the viability of mitochondria, and these results were reversed by the DAPK1-plasmid. Subsequently, functional experiments revealed that hypoxia-stimulated decreases in H9c2 cell viability, as well as increases in apoptosis and caspase-3 activity, were induced by the miR-141 mimic and circRNA 010567-siRNA. However, these results were reversed by the miR-141 inhibitor and DAPK1-plasmid.

Conclusions

Our results demonstrated that circRNA 010567-siRNA played a protective role in hypoxia-induced cardiomyocyte damage via regulating the miR-141/DAPK1 axis, indicating that circRNA 010567-siRNA may be a promising target for MI therapy.

Infarct in the Heart: What's MMP-9 Got to Do with It?

Over the past three decades, numerous studies have shown a strong connection between matrix metalloproteinase 9 (MMP-9) levels and myocardial infarction (MI) mortality and left ventricle remodeling and dysfunction. Despite this fact, clinical trials using MMP-9 inhibitors have been disappointing. This review focuses on the roles of MMP-9 in MI wound healing. Infiltrating leukocytes, cardiomyocytes, fibroblasts, and endothelial cells secrete MMP-9 during all phases of cardiac repair. MMP-9 both exacerbates the inflammatory response and aids in inflammation resolution by stimulating the pro-inflammatory to reparative cell transition. In addition, MMP-9 has a dual effect on neovascularization and prevents an overly stiff scar. Here, we review the complex role of MMP-9 in cardiac wound healing, and highlight the importance of targeting MMP-9 only for its detrimental actions. Therefore, delineating signaling pathways downstream of MMP-9 is critical.

A double-edged sword of immuno-microenvironment in cardiac homeostasis and injury repair

The response of immune cells in cardiac injury is divided into three continuous phases: inflammation, proliferation and maturation. The kinetics of the inflammatory and proliferation phases directly influence the tissue repair. In cardiac homeostasis, cardiac tissue resident macrophages (cTMs) phagocytose bacteria and apoptotic cells. Meanwhile, NK cells prevent the maturation and transport of inflammatory cells. After cardiac injury, cTMs phagocytose the dead cardiomyocytes (CMs), regulate the proliferation and angiogenesis of cardiac progenitor cells. NK cells prevent the cardiac fibrosis, and promote vascularization and angiogenesis. Type 1 macrophages trigger the cardioprotective responses and promote tissue fibrosis in the early stage. Reversely, type 2 macrophages promote cardiac remodeling and angiogenesis in the late stage. Circulating macrophages and neutrophils firstly lead to chronic inflammation by secreting proinflammatory cytokines, and then release anti-inflammatory cytokines and growth factors, which regulate cardiac remodeling. In this process, dendritic cells (DCs) mediate the regulation of monocyte and macrophage recruitment. Recruited eosinophils and Mast cells (MCs) release some mediators which contribute to coronary vasoconstriction, leukocyte recruitment, formation of new blood vessels, scar formation. In adaptive immunity, effector T cells, especially Th17 cells, lead to the pathogenesis of cardiac fibrosis, including the distal fibrosis and scar formation. CMs protectors, Treg cells, inhibit reduce the inflammatory response, then directly trigger the regeneration of local progenitor cell via IL-10. B cells reduce myocardial injury by preserving cardiac function during the resolution of inflammation.

Myeloid interleukin-4 receptor α is essential in postmyocardial infarction healing by regulating inflammation and fibrotic remodeling

Interleukin-4 receptor α (IL4Rα) signaling plays an important role in cardiac remodeling during myocardial infarction (MI). However, the target cell type(s) of IL4Rα signaling during this remodeling remains unclear. Here, we investigated the contribution of endogenous myeloid-specific IL4Rα signaling in cardiac remodeling post-MI. We established a murine myeloid-specific IL4Rα knockout (MyIL4RαKO) model with LysM promoter-driven Cre recombination. Macrophages from MyIL4RαKO mice showed significant downregulation of alternatively activated macrophage markers but an upregulation of classical activated macrophage markers both in vitro and in vivo, indicating the successful inactivation of IL4Rα signaling in macrophages. To examine the role of myeloid IL4Rα during MI, we subjected MyIL4RαKO and littermate floxed control (FC) mice to MI. We found that cardiac function was significantly impaired as a result of myeloid-specific IL4Rα deficiency. This deficiency resulted in a dysregulated inflammatory response consisting of decreased production of anti-inflammatory cytokines. Myeloid IL4Rα deficiency also led to reduced collagen 1 deposition and an imbalance of matrix metalloproteinases (MMPs)/tissue inhibitors of metalloproteinases (TIMPs), with upregulated MMPs and downregulated TIMPs, which resulted in insufficient fibrotic remodeling. In conclusion, this study identifies that myeloid-specific IL4Rα signaling regulates inflammation and fibrotic remodeling during MI. Therefore, myeloid-specific activation of IL4Rα signaling could offer protective benefits after MI.NEW & NOTEWORTHY This study showed, for the first time, the role of endogenous IL4Rα signaling in myeloid cells during cardiac remodeling and the underlying mechanisms. We identified myeloid cells are the critical target cell types of IL4Rα signaling during cardiac remodeling post-MI. Deficiency of myeloid IL4Rα signaling causes deteriorated cardiac function post-MI, due to dysregulated inflammation and insufficient fibrotic remodeling. This study sheds light on the potential of activating myeloid-specific IL4Rα signaling to modify remodeling post-MI. This brings hope to patients with MI and diminishes side effects by cell type-specific instead of whole body treatment.

Understanding the mechanisms that determine extracellular matrix remodeling in the infarcted myocardium

Myocardial Infarction (MI) initiates a series of wound healing events that begins with up-regulation of an inflammatory response and culminates in scar formation. The extracellular matrix (ECM) is intricately involved in all stages from initial break down of existing ECM to synthesis of new ECM to form the scar. This review will summarize our current knowledge on the processes involved in ECM remodeling after MI and identify the gaps that still need to be filled.

TRPC Channels: Dysregulation and Ca2+ Mishandling in Ischemic Heart Disease

Transient receptor potential canonical (TRPC) channels are ubiquitously expressed in excitable and non-excitable cardiac cells where they sense and respond to a wide variety of physical and chemical stimuli. As other TRP channels, TRPC channels may form homo or heterotetrameric ion channels, and they can associate with other membrane receptors and ion channels to regulate intracellular calcium concentration. Dysfunctions of TRPC channels are involved in many types of cardiovascular diseases. Significant increase in the expression of different TRPC isoforms was observed in different animal models of heart infarcts and in vitro experimental models of ischemia and reperfusion. TRPC channel-mediated increase of the intracellular Ca²⁺ concentration seems to be required for the activation of the signaling pathway that plays minor roles in the healthy heart, but they are more relevant for cardiac responses to ischemia, such as the activation of different factors of transcription and cardiac hypertrophy, fibrosis, and angiogenesis. In this review, we highlight the current knowledge regarding TRPC implication in different cellular processes related to ischemia and reperfusion and to heart infarction.

Role of Inflammatory Cell Subtypes in Heart Failure

Inflammation is a well-known feature of heart failure. Studies have shown that while some inflammation is required for repair during injury and is protective, prolonged inflammation leads to myocardial remodeling and apoptosis of cardiac myocytes. Various types of immune cells are implicated in myocardial inflammation and include neutrophils, macrophages, eosinophils, mast cells, natural killer cells, T cells, and B cells. Recent clinical trials have targeted inflammatory cascades as therapy for heart failure with limited success. A better understanding of the temporal course of the infiltration of the different immune cells and their contribution to the inflammatory process may improve the success for therapy. This brief review outlines the major cell types involved in heart failure, and some of their actions are summarized in the supplementary figure.