Chemokines in Myocardial Infarction

Neutrophil-secreted CHI3L1 exacerbates cardiac dysfunction and inflammation after myocardial infarction

Myocardial infarction (MI) triggers acute inflammation, marked by neutrophil infiltration. Although neutrophils are central to this response, the exact role of various neutrophil-derived factors is not fully understood. Clinical studies have linked one such enigmatic factor, chitinase-3 like-1, to MI outcomes. Hence, we investigated its role in post-MI remodeling. We found that chitinase-3 like-1 (CHI3L1) is upregulated after MI and secreted by activated neutrophils but does not directly affect neutrophil activity. To assess whether increased CHI3L1 influences ventricular remodeling, we subjected mice to non-reperfused MI and administered recombinant CHI3L1. Increased CHI3L1 levels worsened ventricular remodeling. In contrast, CHI3L1-deficient mice showed reduced ventricular remodeling after MI. To explore the underlying mechanisms, we assessed interactions with other cells known to be important in ventricular remodeling. Immunoprofiling of infarcted CHI3L1-deficient mouse hearts revealed a faster decline in neutrophil and monocyte numbers, indicating quicker resolution of inflammation. These findings provide direct evidence that CHI3L1 exacerbates ventricular inflammation and remodeling following MI through gain- and loss-of-function approaches.

Decoding the cytokine code for heart failure based on bioinformatics, machine learning and Bayesian networks

BACKGROUND

Despite maximal pharmacological treatment guided by clinical guidelines, the prognosis of heart failure (HF) remains poor, posing a significant public health burden. This necessitates uncovering novel pathological and cardioprotective pathways. Targeting cytokines presents a promising therapeutic strategy for HF, yet their intricate mechanisms in HF progression remain obscure.

METHODS

HF datasets were obtained from the GEO database. Cytokine-related genes were identified through WGCNA and the CytReg database. GO and KEGG enrichment analyses were conducted using the clusterProfiler package. Reactome pathway enrichment analysis and Bayesian regulatory network construction were performed using the CBNplot package. Key genes were identified via LASSO regression and RF algorithms, with diagnostic accuracy evaluated by ROC curves. Potential therapeutic drugs were predicted using the DSigDB database, and immune cell infiltration was assessed with the CIBERSORT package.

RESULTS

We identified 13 cytokine-related genes associated with HF. Enrichment analyses indicated these genes mediate inflammatory responses and immune cell recruitment. Bayesian network analysis revealed two cytokine regulatory chains: IL34-CCL5-CCL4 and IL34-CCL5-CXCL12. Machine learning algorithms identified five key cytokine genes: CCL4, CCL5, CXCL12, CXCL14, and IL34. The DSigDB database predicted 47 potential therapeutic drugs, including Proscillaridin. Immune infiltration analysis showed significant differences in seven immune cell types between HF and healthy samples.

CONCLUSION

Our study provides insights into cytokines' molecular mechanisms in HF pathophysiology and highlights potential immunomodulatory strategies, gene therapies, and candidate drugs. Future research should validate these findings in clinical settings to develop effective HF therapies.

Reperfused Myocardial Infarction: The Road to CCS Classification of Acute MI and Beyond

The Canadian Cardiovascular Society recently put forth a new classification of acute reperfused myocardial infarction (MI) based on stages of myocardial injury. Backed by more than 5 decades of intense investigation in the field, the key message of this new classification is that not all MIs are the same and that the type and extent of myocardial injury should be considered in diagnosing and treating MI. We review the literature with the goal of highlighting the progressive advances that enabled the synthesis of the Canadian Cardiovascular Society classification into 4 distinct stages of tissue injury. We emphasize the major breakthroughs from insights gained from experimental, translational, and clinical studies to date. We also identify current gaps in knowledge and critical research directions that need to be pursued to improve patient care and reduce post-MI complications such as chronic heart failure and malignant arrhythmias, whose risk is linked to stage and extent of myocardial injury.

BRD4 inhibition rewires cardiac macrophages toward a protective phenotype marked by low MHC class II expression

Bromodomain and extraterminal domain (BET) proteins, including BRD4, bind acetylated chromatin and coactivate gene transcription. A BET inhibitor, JQ1, prevents and reverses pathological cardiac remodeling in preclinical models of heart failure. However, the underlying cellular mechanisms by which JQ1 improves cardiac structure and function remain poorly defined. Here, we demonstrate that BRD4 knockdown reduced expression of genes encoding CC chemokines in cardiac fibroblasts, suggesting a role for this epigenetic reader in controlling fibroblast-immune cell cross talk. Consistent with this, JQ1 dramatically suppressed recruitment of monocytes to the heart in response to stress. Normal mouse hearts were found to have approximately equivalent numbers of major histocompatibility complex (MHC-II)high and MHC-IIlow resident macrophages, whereas MHC-IIlow macrophages predominated following JQ1 treatment. Single-cell RNA-seq data confirmed that JQ1 treatment or BRD4 knockout in CX3CR1+ cells reduced MHC-II gene expression in cardiac macrophages, and studies with cultured macrophages further illustrated a cell autonomous role for BET proteins in controlling the MHC-II axis. Bulk RNA-seq analysis demonstrated that JQ1 blocked pro-inflammatory macrophage gene expression through a mechanism that likely involves repression of NF-κB signaling. JQ1 treatment reduced cardiac infarct size in mice subjected to ischemia/reperfusion. Our findings illustrate that BET inhibition affords a powerful pharmacological approach to manipulate monocyte-derived and resident macrophages in the heart. Such an approach has the potential to enhance the reparative phenotype of macrophages to promote wound healing and limit infarct expansion following myocardial ischemia.NEW & NOTEWORTHY BRD4 inhibition blocks stress-induced recruitment of pro-inflammatory monocytes to the heart. BRD4 inhibition reprograms resident cardiac macrophages toward a reparative phenotype marked by reduced NF-κB signaling and diminished MHC-II expression. BRD4 inhibition reduces infarct size in an acute model of ischemia/reperfusion injury in mice.

Postoperative evaluation of interleukin-8 and C1q/TNF-related protein-12 in patients undergoing coronary artery bypass graft surgery

OBJECTIVE

Coronary artery bypass graft surgery is one of the most frequently performed surgeries worldwide. Coronary artery bypass graft surgery induces an inflammatory response. Interleukin-8 is a pro-inflammatory cytokine that plays a role in the pathogenesis of cardiovascular diseases. C1q/TNF-related protein-12 is implicated in mitigating inflammation and cardiomyocyte damage. This study aimed to compare interleukin-8 and C1q/TNF-related protein-12 levels before and 45 days after coronary artery bypass graft surgery.

METHODS

A total of 43 patients who underwent coronary artery bypass graft surgery were studied. Serum concentrations of interleukin-8 and C1q/TNF-related protein-12 were evaluated using the enzyme-linked immunosorbent assay method before and 45 days after the surgery.

RESULTS

No significant differences were observed in interleukin-8 levels between pre- and post-coronary artery bypass graft surgery (p=0.077). However, serum levels of C1q/TNF-related protein-12 were found to be lower 45 days after coronary artery bypass graft surgery compared to pre-surgery levels (p<0.001). Moreover, changes in C1q/TNF-related protein-12 were not associated with diabetes, hypertension, and body mass index (p>0.05), but C1q/TNF-related protein-12 alterations were found to be associated with opium addiction.

CONCLUSION

These findings suggest that the evaluation of C1q/TNF-related protein-12 can be beneficial for the late assessment of post-coronary artery bypass graft surgery inflammation. The reduction of C1q/TNF-related protein-12 levels might indicate increased levels of inflammation after surgery at this time point, which requires the assessment of further inflammatory factors to confirm this finding.

Macrophages after myocardial infarction: Mechanisms for repairing and potential as therapeutic approaches

Macrophages - one of the crucial immune cells, are recruited to the cardiac tissue by chemokines, cytokines and upregulated endothelial adhesion molecules after myocardial infarction (MI). During the course of inflammation in the cardiac tissue, necrotic cells and matrix debris is phagocytosed by M1 macrophages. During the resolution phase of cardiac inflammation, M2 macrophages promote cardiac recovery. Suppression or over expression of both the M1 and M2 macrophage subtypes significantly affect the reparation of infarction. Stem cells therapy, cytokine regulation and immune cells therapy are considered as effective interventions to regulate the phenotypic transformation of cardiac macrophages after MI. Intervention with macrophages in the myocardium has shown unique advantages. In this review, the mechanisms and role of macrophages in the development of MI are elaborated in detail, the promising therapeutic methods for regulating macrophage phenotypes, their limitations and possible future research directions are discussed.

Shedding of membrane complement inhibitors CD59 and CD46 into the circulation is associated with poor prognosis in acute coronary syndrome patients: a cohort study

INTRODUCTION

The role of the complement inhibitory proteins CD46 and CD59 in the immune response to an acute coronary syndrome (ACS) is unknown. We investigated the relationships between the shedding of CD46 and CD59 into the circulation, reflected by plasma levels of soluble CD46 and CD59, and the risk for post-ACS complications.

METHODS

We measured plasma sCD46 and sCD59 in a cohort of 546 ACS patients within 24 h after hospital admission, and after 6-weeks in a subgroup of 114 patients. Study outcomes were incident heart failure (HF), major adverse cardiovascular events (MACE) and mortality during a median follow-up period of up to 3.3 years. Echocardiography at 1-year was performed in the follow-up subgroup.

RESULTS

Elevated sCD46 and sCD59 were correlated with increased levels of inflammatory mediators and metalloproteinases in plasma, and were associated with increased risk for MACE in Cox proportional hazard models adjusted for cardiovascular risk factors and revascularization [HR 95% CI 1.24 (1.02-1.52), p = 0.034 for sCD46 and 1.18 (1.00-1.38), p = 0.049 for sCD59]. Elevated sCD59 was also associated with higher incidence of HF [HR 95% CI 1.41 (1.15-1.74), p = 0.001], and with lower left ventricular ejection fraction at 1-year post-ACS (Spearman r = - 0.234, p = 0.020). We found no associations between plasma levels of the proteins at 6 weeks and outcomes.

CONCLUSIONS

Shedding of the complement regulators CD46 and CD59 in plasma in the acute phase of ACS is associated with a negative prognosis. Plasma sCD46 and sCD59 could reflect the degree of local immune activation and serve as prognostic biomarkers in ACS patients.

Macrophage-mediated heart repair and remodeling: A promising therapeutic target for post-myocardial infarction heart failure

Heart failure (HF) remains prevalent in patients who survived myocardial infarction (MI). Despite the accessibility of the primary percutaneous coronary intervention and medications that alleviate ventricular remodeling with functional improvement, there is an urgent need for clinicians and basic scientists to further reveal the mechanisms behind post-MI HF as well as investigate earlier and more efficient treatment after MI. Growing numbers of studies have highlighted the crucial role of macrophages in cardiac repair and remodeling following MI, and timely intervention targeting the immune response via macrophages may represent a promising therapeutic avenue. Recently, technology such as single-cell sequencing has provided us with an updated and in-depth understanding of the role of macrophages in MI. Meanwhile, the development of biomaterials has made it possible for macrophage-targeted therapy. Thus, an overall and thorough understanding of the role of macrophages in post-MI HF and the current development status of macrophage-based therapy will assist in the further study and development of macrophage-targeted treatment for post-infarction cardiac remodeling. This review synthesizes the spatiotemporal dynamics, function, mechanism and signaling of macrophages in the process of HF after MI, as well as discusses the emerging bio-materials and possible therapeutic agents targeting macrophages for post-MI HF.

Characterization of a novel mitophagy-related 5-genes signature for diagnosis of acute myocardial infarction

Myocardial infarction (MI) and the ensuing heart failure (HF) remain the main cause of morbidity and mortality worldwide. One of the strategies to combat MI and HF lies in the ability to accurately predict the onset of these disorders. Alterations in mitochondrial homeostasis have been reported to be involved in the pathogenesis of various cardiovascular diseases (CVDs). In this regard, perturbations to mitochondrial dynamics leading to impaired clearance of dysfunctional mitochondria have been previously established to be a crucial trigger for MI/HF. In this study, we found that MI patients could be classified into three clusters based on the expression levels of mitophagy-related genes and consensus clustering. We identified a mitophagy-related diagnostic 5-genes signature for MI using support vector machines-Recursive Feature Elimination (SVM-RFE) and random forest, with the area under the ROC curve (AUC) value of the predictive model at 0.813. Additionally, the single-cell transcriptome and pseudo-time analyses showed that the mitoscore was significantly upregulated in macrophages, endothelial cells, pericytes, fibroblasts and monocytes in patients with ischemic cardiomyopathy, while sequestosome 1 (SQSTM1) exhibited remarkable increase in the infarcted (ICM) and non-infarcted (ICMN) myocardium samples dissected from the left ventricle compared with control samples. Lastly, through analysis of peripheral blood from MI patients, we found that the expression of SQSTM1 is positively correlated with troponin-T (P < 0.0001, R = 0.4195, R2 = 0.1759). Therefore, this study provides the rationale for a cell-specific mitophagy-related gene signature as an additional supporting diagnostic for CVDs.

Elucidating the role of chemokines in inflammaging associated atherosclerotic cardiovascular diseases

Age-related inflammation or inflammaging is a critical deciding factor of physiological homeostasis during aging. Cardiovascular diseases (CVDs) are exquisitely associated with aging and inflammation and are one of the leading causes of high mortality in the elderly population. Inflammaging comprises dysregulation of crosstalk between the vascular and cardiac tissues that deteriorates the vasculature network leading to development of atherosclerosis and atherosclerotic-associated CVDs in elderly populations. Leukocyte differentiation, migration and recruitment holds a crucial position in both inflammaging and atherosclerotic CVDs through relaying the activity of an intricate network of inflammation-associated protein-protein interactions. Among these interactions, small immunoproteins such as chemokines play a major role in the progression of inflammaging and atherosclerosis. Chemokines are actively involved in lymphocyte migration and severe inflammatory response at the site of injury. They relay their functions via chemokine-G protein-coupled receptors-glycosaminoglycan signaling axis and is a principal part for the detection of age-related atherosclerosis and related CVDs. This review focuses on highlighting the detailed intricacies of the effects of chemokine-receptor interaction and chemokine oligomerization on lymphocyte recruitment and its evident role in clinical manifestations of atherosclerosis and related CVDs. Further, the role of chemokine mediated signaling for formulating next-generation therapeutics against atherosclerosis has also been discussed.

The Influence of Metabolic Risk Factors on the Inflammatory Response Triggered by Myocardial Infarction: Bridging Pathophysiology to Treatment

Myocardial infarction (MI) sets off a complex inflammatory cascade that is crucial for effective cardiac healing and scar formation. Yet, if this response becomes excessive or uncontrolled, it can lead to cardiovascular complications. This review aims to provide a comprehensive overview of the tightly regulated local inflammatory response triggered in the early post-MI phase involving cardiomyocytes, (myo)fibroblasts, endothelial cells, and infiltrating immune cells. Next, we explore how the bone marrow and extramedullary hematopoiesis (such as in the spleen) contribute to sustaining immune cell supply at a cardiac level. Lastly, we discuss recent findings on how metabolic cardiovascular risk factors, including hypercholesterolemia, hypertriglyceridemia, diabetes, and hypertension, disrupt this immunological response and explore the potential modulatory effects of lifestyle habits and pharmacological interventions. Understanding how different metabolic risk factors influence the inflammatory response triggered by MI and unraveling the underlying molecular and cellular mechanisms may pave the way for developing personalized therapeutic approaches based on the patient's metabolic profile. Similarly, delving deeper into the impact of lifestyle modifications on the inflammatory response post-MI is crucial. These insights may enable the adoption of more effective strategies to manage post-MI inflammation and improve cardiovascular health outcomes in a holistic manner.

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.

Macrophages promote the transition from myocardial ischemia reperfusion injury to cardiac fibrosis in mice through GMCSF/CCL2/CCR2 and phenotype switching

Following acute myocardial ischemia reperfusion (MIR), macrophages infiltrate damaged cardiac tissue and alter their polarization phenotype to respond to acute inflammation and chronic fibrotic remodeling. In this study we investigated the role of macrophages in post-ischemic myocardial fibrosis and explored therapeutic targets for myocardial fibrosis. Male mice were subjected to ligation of the left coronary artery for 30 min. We first detected the levels of chemokines in heart tissue that recruited immune cells infiltrating into the heart, and found that granulocyte-macrophage colony-stimulating factor (GMCSF) released by mouse cardiac microvascular endothelial cells (MCMECs) peaked at 6 h after reperfusion, and c-c motif chemokine ligand 2 (CCL2) released by GMCSF-induced macrophages peaked at 24 h after reperfusion. In co-culture of BMDMs with MCMECs, we demonstrated that GMCSF derived from MCMECs stimulated the release of CCL2 by BMDMs and effectively promoted the migration of BMDMs. We also confirmed that GMCSF promoted M1 polarization of macrophages in vitro, while GMCSF neutralizing antibodies (NTABs) blocked CCL2/CCR2 signaling. In MIR mouse heart, we showed that GMCSF activated CCL2/CCR2 signaling to promote NLRP3/caspase-1/IL-1β-mediated and amplified inflammatory damage. Knockdown of CC chemokine receptor 2 gene (CCR2-/-), or administration of specific CCR2 inhibitor RS102895 (5 mg/kg per 12 h, i.p., one day before MIR and continuously until the end of the experiment) effectively reduced the area of myocardial infarction, and down-regulated inflammatory mediators and NLRP3/Caspase-1/IL-1β signaling. Mass cytometry confirmed that M2 macrophages played an important role during fibrosis, while macrophage-depleted mice exhibited significantly reduced transforming growth factor-β (Tgf-β) levels in heart tissue after MIR. In co-culture of macrophages with fibroblasts, treatment with recombinant mouse CCL2 stimulated macrophages to release a large amount of Tgf-β, and promoted the release of Col1α1 by fibroblasts. This effect was diminished in BMDMs from CCR2-/- mice. After knocking out or inhibiting CCR2-gene, the levels of Tgf-β were significantly reduced, as was the level of myocardial fibrosis, and cardiac function was protected. This study confirms that the acute injury to chronic fibrosis transition after MIR in mice is mediated by GMCSF/CCL2/CCR2 signaling in macrophages through NLRP3 inflammatory cascade and the phenotype switching.

Chemokine CCL2 promotes cardiac regeneration and repair in myocardial infarction mice via activation of the JNK/STAT3 axis

Stimulation of adult cardiomyocyte proliferation is a promising strategy for treating myocardial infarction (MI). Earlier studies have shown increased CCL2 levels in plasma and cardiac tissue both in MI patients and mouse models. In present study we investigated the role of CCL2 in cardiac regeneration and the underlying mechanisms. MI was induced in adult mice by permanent ligation of the left anterior descending artery, we showed that the serum and cardiac CCL2 levels were significantly increased in MI mice. Intramyocardial injection of recombinant CCL2 (rCCL2, 1 μg) immediately after the surgery significantly promoted cardiomyocyte proliferation, improved survival rate and cardiac function, and diminished scar sizes in post-MI mice. Alongside these beneficial effects, we observed an increased angiogenesis and decreased cardiomyocyte apoptosis in post-MI mice. Conversely, treatment with a selective CCL2 synthesis inhibitor Bindarit (30 μM) suppressed both CCL2 expression and cardiomyocyte proliferation in P1 neonatal rat ventricle myocytes (NRVMs). We demonstrated in NRVMs that the CCL2 stimulated cardiomyocyte proliferation through STAT3 signaling: treatment with rCCL2 (100 ng/mL) significantly increased the phosphorylation levels of STAT3, whereas a STAT3 phosphorylation inhibitor Stattic (30 μM) suppressed rCCL2-induced cardiomyocyte proliferation. In conclusion, this study suggests that CCL2 promotes cardiac regeneration via activation of STAT3 signaling, underscoring its potential as a therapeutic agent for managing MI and associated heart failure.

C-C Motif Chemokine 2 Regulates Macrophage Polarization and Contributes to Myocardial Infarction Healing

Macrophages are crucial immune cells that play essential roles in the healing of myocardial infarction (MI), undergoing continuous polarization throughout this process. C-C motif chemokine 2 (CCL2) is a chemokine that regulates inflammatory responses during MI. However, the extent to which CCL2 influences macrophage polarization and MI healing remains incompletely understood. In this study, we investigate the role of CCL2 in macrophage polarization and MI healing. Our findings reveal that CCL2 is differentially expressed in lipopolysaccharide (LPS)-induced M1 and interleukin (IL)-4-induced M2 RAW264.7 macrophages. Knockdown of CCL2 attenuates TNF-α secretion stimulated by LPS, while overexpression of CCL2 mitigates IL-10 production triggered by IL-4 in these macrophages. Moreover, CCL2 deficiency disrupts LPS-induced M1 polarization, whereas CCL2 overexpression reduces M2 polarization of RAW264.7 macrophages induced by IL-4. Further exploration indicates that the promotion of M1 polarization by CCL2 is significantly impaired by inhibition of the p38-mediated MAPK pathway and NF-κB pathway. In a MI mouse model, CCL2 knockdown remarkably reduces infarct size, collagen synthesis, and the expression of cardiac fibrosis and hypertrophy markers. The activity of the p38-mediated MAPK pathway and NF-κB pathway is downregulated by CCL2 knockdown as well. Additionally, the number of total macrophages and M1 macrophages in the infarct decreases, while the number of M2 macrophages increases upon CCL2 deficiency. In conclusion, these results suggest that CCL2 is a key regulator of macrophage polarization, controlling MI healing in vivo.

TAX1BP1 downregulation by STAT3 in cardiac fibroblasts contributes to diabetes-induced heart failure with preserved ejection fraction

Heart failure (HF) with preserved ejection fraction (HFpEF) is now the most common form of HF and has been reported to be closely related to diabetes. Accumulating evidence suggests that HFpEF patients exhibit cardiac fibrosis. This study investigates whether direct targeted inhibition of the activation of cardiac fibroblasts (CFs), the main effector cells in cardiac fibrosis, improves diabetes-induced HFpEF and elucidates the underlying mechanisms. Twenty-week-old db/db mice exhibited HFpEF, as confirmed by echocardiography and hemodynamic measurements. Proteomics was performed on CFs isolated from the hearts of 20-week-old C57BL/6 and db/db mice. Bioinformatic prediction was used to identify target proteins. Experimental validation was performed in both high glucose (HG)-treated neonatal mouse CFs (NMCFs) and diabetic hearts. TAX1 binding protein 1 (TAX1BP1) was identified as the most significantly differentially expressed protein between 20-week-old C57BL/6 and db/db mice. TAX1BP1 mRNA and protein were markedly downregulated in CFs from diabetic hearts and HG-cultured NMCFs. Overexpression of TAX1BP1 profoundly inhibited HG/diabetes-induced NF-κB nuclear translocation and collagen synthesis in CFs, improved cardiac fibrosis, hypertrophy, inflammation and HFpEF in diabetic mice. Mechanistically, signal transducer and activator of transcription 3 (STAT3), which is phosphorylated and translocated from the cytoplasm into the nucleus under hyperglycemic conditions, bound to TAX1BP1 promoter and blocked TAX1BP1 transcriptional activity, consequently promoting NF-κB nuclear translocation and collagen synthesis in CFs, aggravating cardiac fibrosis, hypertrophy and inflammation, leading to HFpEF in db/db mice. Taken together, our findings demonstrate that targeting regulation of STAT3-TAX1BP1-NF-κB signaling in CFs may be a promising therapeutic approach for diabetes-induced HFpEF.

Predictors of chronic thromboembolic pulmonary hypertension in patients with submassive pulmonary embolism treated with catheter-directed thrombolysis versus anticoagulation alone: A secondary analysis of the SUNSET sPE trial

OBJECTIVE

Chronic thromboembolic pulmonary hypertension (CTEPH) after pulmonary embolism (PE) is a morbid complication with suboptimal treatment. We aimed to evaluate the biomarker profile and functional outcomes in patients with submassive PE (sPE) treated with catheter-directed thrombolysis (CDT) compared with anticoagulation alone (ACA). We performed a secondary biomarker and survey analysis of the SUNSET sPE (standard vs ultrasound-assisted catheter thrombolysis for submassive pulmonary embolism) randomized trial comparing standard CDT to ultrasound-assisted thrombolysis in patients with sPE.

METHODS

As a part of the SUNSET sPE study, patients who did not receive an intervention were enrolled in the medical (ACA) arm. The biomarkers associated with CTEPH in the literature (ie, CCL2, CXCL10, PTX3, GDF-15, RAGE, BCA-1, TFPI) were collected and measured using a multiplex assay at diagnosis, discharge, and 3-month follow-up. Patients underwent a 6-minute walk test and answered quality-of-life questionnaires (pulmonary embolism quality of life; University of California, San Diego, shortness of breath questionnaire; 36-item short-form survey) at 3 months after diagnosis. Comparisons were made using the Student t test. Nonparametric tests were used when the distributions were not normal. Significance was set at P ≤ .05.

RESULTS

A total of 72 patients (age, 56 ± 15 years; 40.3% women) were included in the present analysis. Of these 72 patients, 53 underwent CDT and 19 were included in the ACA arm. The baseline right ventricle/left ventricle ratios were similar between the two groups (CST, 1.8; ACA, 1.7). The survival and complication rates were similar between the two groups. At discharge, CXCL10 (768.9 ± 148.6 pg/mL vs 3032.0 ± 1201.0 pg/mL; P = .018) and PTX3 (3203.5 ± 1298.0 pg/mL vs 12,716.2 ± 6961.5 pg/mL; P = .029) were lower in the CDT group and displayed a quicker return to baseline than in the ACA group. This trend, although not significant, was also seen with the other biomarkers. At 3 months, the 6-minute walking distance and quality-of-life scores were similar between both groups.

CONCLUSIONS

In patients with sPE, the biomarkers of CTEPH were lower with CDT compared with ACA. At 3 months, both groups demonstrated similar biomarker levels, 6-minute walking distances, and quality-of-life scores.

Mitochondrial Impairment: A Link for Inflammatory Responses Activation in the Cardiorenal Syndrome Type 4

Cardiorenal syndrome type 4 (CRS type 4) occurs when chronic kidney disease (CKD) leads to cardiovascular damage, resulting in high morbidity and mortality rates. Mitochondria, vital organelles responsible for essential cellular functions, can become dysfunctional in CKD. This dysfunction can trigger inflammatory responses in distant organs by releasing Damage-associated molecular patterns (DAMPs). These DAMPs are recognized by immune receptors within cells, including Toll-like receptors (TLR) like TLR2, TLR4, and TLR9, the nucleotide-binding domain, leucine-rich-containing family pyrin domain-containing-3 (NLRP3) inflammasome, and the cyclic guanosine monophosphate (cGMP)-adenosine monophosphate (AMP) synthase (cGAS)-stimulator of interferon genes (cGAS-STING) pathway. Activation of these immune receptors leads to the increased expression of cytokines and chemokines. Excessive chemokine stimulation results in the recruitment of inflammatory cells into tissues, causing chronic damage. Experimental studies have demonstrated that chemokines are upregulated in the heart during CKD, contributing to CRS type 4. Conversely, chemokine inhibitors have been shown to reduce chronic inflammation and prevent cardiorenal impairment. However, the molecular connection between mitochondrial DAMPs and inflammatory pathways responsible for chemokine overactivation in CRS type 4 has not been explored. In this review, we delve into mechanistic insights and discuss how various mitochondrial DAMPs released by the kidney during CKD can activate TLRs, NLRP3, and cGAS-STING immune pathways in the heart. This activation leads to the upregulation of chemokines, ultimately culminating in the establishment of CRS type 4. Furthermore, we propose using chemokine inhibitors as potential strategies for preventing CRS type 4.

Neutrophils for Revascularization Require Activation of CCR6 and CCL20 by TNFα

BACKGROUND

Activation of immune-inflammatory pathways involving TNFα (tumor necrosis factor alpha) signaling is critical for revascularization and peripheral muscle tissue repair after ischemic injury. However, mechanisms of TNFα-driven inflammatory cascades directing recruitment of proangiogenic immune cells to sites of ischemia are unknown.

METHODS

Muscle tissue revascularization after permanent femoral artery ligation was monitored in mutant mice by laser Doppler imaging and light sheet fluorescence microscopy. TNFα-mediated signaling and the role of the CCL20 (C-C motif chemokine ligand 20)-CCR6 (C-C chemokine receptor 6) axis for formation of new vessels was studied in vitro and in vivo using bone marrow transplantation, flow cytometry, as well as biochemical and molecular biological techniques.

RESULTS

TNFα-mediated activation of TNFR (tumor necrosis factor receptor) 1 but not TNFR2 was found to be required for postischemic muscle tissue revascularization. Bone marrow-derived CCR6+ neutrophil granulocytes were identified as a previously undescribed TNFα-induced population of proangiogenic neutrophils, characterized by increased expression of VEGFA (vascular endothelial growth factor A). Mechanistically, postischemic activation of TNFR1 induced expression of the CCL20 in vascular cells and promoted translocation of the CCL20 receptor CCR6 to the cell surface of neutrophils, essentially conditioning VEGFA-expressing proangiogenic neutrophils for CCL20-dependent recruitment to sites of ischemia. Moreover, impaired revascularization of ischemic peripheral muscle tissue in diabetic mice was associated with reduced numbers of proangiogenic neutrophils and diminished CCL20 expression. Administration of recombinant CCL20 enhanced recruitment of proangiogenic neutrophils and improved revascularization of diabetic ischemic skeletal muscles, which was sustained by sequential treatment with fluvastatin.

CONCLUSIONS

We demonstrate that site-specific activation of the CCL20-CCR6 axis via TNFα recruits proangiogenic VEGFA-expressing neutrophils to sites of ischemic injury for initiation of muscle tissue revascularization. The findings provide an attractive option for tissue revascularization, particularly under diabetic conditions.

miRNAs Epigenetic Tuning of Wall Remodeling in the Early Phase after Myocardial Infarction: A Novel Epidrug Approach

Myocardial infarction (MI) is one of the leading causes of death in Western countries. An early diagnosis decreases subsequent severe complications such as wall remodeling or heart failure and improves treatments and interventions. Novel therapeutic targets have been recognized and, together with the development of direct and indirect epidrugs, the role of non-coding RNAs (ncRNAs) yields great expectancy. ncRNAs are a group of RNAs not translated into a product and, among them, microRNAs (miRNAs) are the most investigated subgroup since they are involved in several pathological processes related to MI and post-MI phases such as inflammation, apoptosis, angiogenesis, and fibrosis. These processes and pathways are finely tuned by miRNAs via complex mechanisms. We are at the beginning of the investigation and the main paths are still underexplored. In this review, we provide a comprehensive discussion of the recent findings on epigenetic changes involved in the first phases after MI as well as on the role of the several miRNAs. We focused on miRNAs function and on their relationship with key molecules and cells involved in healing processes after an ischemic accident, while also giving insight into the discrepancy between males and females in the prognosis of cardiovascular diseases.

Skin wound healing as a mirror to cardiac wound healing

NEW FINDINGS

What is the topic of this review? Wound healing is a general response of the body to injury and can be divided into three phases: inflammation, inflammation resolution and repair. In this review, we compare the wound-healing response of the skin after an injury and the wound-healing response of the heart after a myocardial infarction. What advances does it highlight? We highlight differences and similarities between skin and cardiac wound healing and summarize how skin can be used to provide information about the heart.

ABSTRACT

Wound healing is a general response of the body to injury. All organs share in common three response elements to wound healing: inflammation to prevent infection and stimulate the removal of dead cells, active anti-inflammatory signalling to turn off the inflammatory response, and a repair phase characterized by extracellular matrix scar formation. The extent of scar formed depends on the ability of endogenous cells that populate each organ to regenerate. The skin has keratinocytes that have regenerative capacity, and in general, wounds are fully re-epithelialized. Heart, in contrast, has cardiac myocytes that have little to no regenerative capacity, and necrotic myocytes are entirely replaced by scars. Despite differences in tissue regeneration, the skin and heart share many wound-healing properties that can be exploited to predict the cardiac response to pathology. We summarize in this review article our current understanding of how the response of the skin to a wounding event can inform us about the ability of the myocardium to respond to a myocardial infarction.

p53 Regulates the Extent of Fibroblast Proliferation and Fibrosis in Left Ventricle Pressure Overload

BACKGROUND

Cardiomyopathy is characterized by the pathological accumulation of resident cardiac fibroblasts that deposit ECM (extracellular matrix) and generate a fibrotic scar. However, the mechanisms that control the timing and extent of cardiac fibroblast proliferation and ECM production are not known, hampering the development of antifibrotic strategies to prevent heart failure.

METHODS

We used the Tcf21 (transcription factor 21)MerCreMer mouse line for fibroblast-specific lineage tracing and p53 (tumor protein p53) gene deletion. We characterized cardiac physiology and used single-cell RNA-sequencing and in vitro studies to investigate the p53-dependent mechanisms regulating cardiac fibroblast cell cycle and fibrosis in left ventricular pressure overload induced by transaortic constriction.

RESULTS

Cardiac fibroblast proliferation occurs primarily between days 7 and 14 following transaortic constriction in mice, correlating with alterations in p53-dependent gene expression. p53 deletion in fibroblasts led to a striking accumulation of Tcf21-lineage cardiac fibroblasts within the normal proliferative window and precipitated a robust fibrotic response to left ventricular pressure overload. However, excessive interstitial and perivascular fibrosis does not develop until after cardiac fibroblasts exit the cell cycle. Single-cell RNA sequencing revealed p53 null fibroblasts unexpectedly express lower levels of genes encoding important ECM proteins while they exhibit an inappropriately proliferative phenotype. in vitro studies establish a role for p53 in suppressing the proliferative fibroblast phenotype, which facilitates the expression and secretion of ECM proteins. Importantly, Cdkn2a (cyclin-dependent kinase inhibitor 2a) expression and the p16Ink4a-retinoblastoma cell cycle control pathway is induced in p53 null cardiac fibroblasts, which may eventually contribute to cell cycle exit and fulminant scar formation.

CONCLUSIONS

This study reveals a mechanism regulating cardiac fibroblast accumulation and ECM secretion, orchestrated in part by p53-dependent cell cycle control that governs the timing and extent of fibrosis in left ventricular pressure overload.

Effector T cell chemokine IP-10 predicts cardiac recovery and clinical outcomes post-myocardial infarction

Background and aims

Preclinical data suggest that activation of the adaptive immune system is critical for myocardial repair processes in acute myocardial infarction. The aim of the present study was to determine the clinical value of baseline effector T cell chemokine IP-10 blood levels in the acute phase of ST-segment elevation myocardial infarction (STEMI) for the prediction of the left ventricular function changes and cardiovascular outcomes after STEMI.

Methods

Serum IP-10 levels were retrospectively quantified in two independent cohorts of STEMI patients undergoing primary percutaneous coronary intervention.

Results

We report a biphasic response of the effector T cell trafficking chemokine IP-10 characterized by an initial increase of its serum levels in the acute phase of STEMI followed by a rapid reduction at 90min post reperfusion. Patients at the highest IP-10 tertile presented also with more CD4 effector memory T cells (CD4 TEM cells), but not other T cell subtypes, in blood. In the Newcastle cohort (n=47), patients in the highest IP-10 tertile or CD4 TEM cells at admission exhibited an improved cardiac systolic function 12 weeks after STEMI compared to patients in the lowest IP-10 tertile. In the Heidelberg cohort (n=331), STEMI patients were followed for a median of 540 days for major adverse cardiovascular events (MACE). Patients presenting with higher serum IP-10 levels at admission had a lower risk for MACE after adjustment for traditional risk factors, CRP and high-sensitivity troponin-T levels (highest vs. rest quarters: HR [95% CI]=0.420 [0.218-0.808]).

Conclusion

Increased serum levels of IP-10 in the acute phase of STEMI predict a better recovery in cardiac systolic function and less adverse events in patients after STEMI.

Screening of the best time window for MSC transplantation to treat acute myocardial infarction with SDF-1α antibody-loaded targeted ultrasonic microbubbles: An in vivo study in miniswine

The present study aimed to screen the best time window for the transplantation of bone marrow mesenchymal stem cells (MSCs) after acute myocardial infarction (MI) through targeted ultrasound microbubbles loaded with SDF-1α antibody. Thirty-six MI miniswine were randomly divided into six experimental groups according to the duration after infarction (1 day, 3 days, 1 week, 2 weeks, 3 weeks, and 4 weeks after infarction). MSCs were labeled with BrdU and then injected through the coronary artery in the stem cell transplantation group to detect the number of transplanted MSCs at different time points after MI. Three miniswine were randomly selected as the control group (sham operation: open chest without ligation of the coronary artery). All SDF-1α groups and control groups were injected with a targeted microbubble ultrasound contrast agent. The values of the myocardial perfusion parameters (A, β, and A × β) were determined. A _T, β _T, and (A × β)_T varied with time and peaked 1 week after MI (P < 0.05). The number of transplanted stem cells in the myocardium through coronary injection of MSCs at 1 week was the greatest and consistent with the changing tendency of A _T, β _T, and (A × β)_T (r = 0.658, 0.778, 0.777, P < 0.05). β _T(X), (A × β)_T(X), and the number of transplanted stem cells was used to establish the regression equation as follows: Y = 36.11 + 17.601X; Y = 50.023 + 3.348X (R ² = 0.605, 0.604, P < 0.05). The best time window for transplanting stem cells was 1 week after MI. The myocardial perfusion parameters of the SDF-1α targeted contrast agent can be used to predict the number of transplanted stem cells in the myocardial tissue.

Cardiac Reverse Remodeling in Ischemic Heart Disease with Novel Therapies for Heart Failure with Reduced Ejection Fraction

Despite the improvements in the treatment of coronary artery disease (CAD) and acute myocardial infarction (MI) over the past 20 years, ischemic heart disease (IHD) continues to be the most common cause of heart failure (HF). In clinical trials, over 70% of patients diagnosed with HF had IHD as the underlying cause. Furthermore, IHD predicts a worse outcome for patients with HF, leading to a substantial increase in late morbidity, mortality, and healthcare costs. In recent years, new pharmacological therapies have emerged for the treatment of HF, such as sodium-glucose cotransporter-2 inhibitors, angiotensin receptor-neprilysin inhibitors, selective cardiac myosin activators, and oral soluble guanylate cyclase stimulators, demonstrating clear or potential benefits in patients with HF with reduced ejection fraction. Interventional strategies such as cardiac resynchronization therapy, cardiac contractility modulation, or baroreflex activation therapy might provide additional therapeutic benefits by improving symptoms and promoting reverse remodeling. Furthermore, cardiac regenerative therapies such as stem cell transplantation could become a new therapeutic resource in the management of HF. By analyzing the existing data from the literature, this review aims to evaluate the impact of new HF therapies in patients with IHD in order to gain further insight into the best form of therapeutic management for this large proportion of HF patients.

The Role of Cytokines in Cholesterol Accumulation in Cells and Atherosclerosis Progression

Atherosclerosis is the most common cardiovascular disease and is the number one cause of death worldwide. Today, atherosclerosis is a multifactorial chronic inflammatory disease with an autoimmune component, accompanied by the accumulation of cholesterol in the vessel wall and the formation of atherosclerotic plaques, endothelial dysfunction, and chronic inflammation. In the process of accumulation of atherogenic lipids, cells of the immune system, such as monocytes, macrophages, dendritic cells, etc., play an important role, producing and/or activating the production of various cytokines—interferons, interleukins, chemokines. In this review, we have tried to summarize the most important cytokines involved in the processes of atherogenesis.

Post-myocardial infarction fibrosis: Pathophysiology, examination, and intervention

Cardiac fibrosis plays an indispensable role in cardiac tissue homeostasis and repair after myocardial infarction (MI). The cardiac fibroblast-to-myofibroblast differentiation and extracellular matrix collagen deposition are the hallmarks of cardiac fibrosis, which are modulated by multiple signaling pathways and various types of cells in time-dependent manners. Our understanding of the development of cardiac fibrosis after MI has evolved in basic and clinical researches, and the regulation of fibrotic remodeling may facilitate novel diagnostic and therapeutic strategies, and finally improve outcomes. Here, we aim to elaborate pathophysiology, examination and intervention of cardiac fibrosis after MI.

Monocyte chemokine receptors as therapeutic targets in cardiovascular diseases

Chemokine receptors are fundamental in many processes related to cardiovascular diseases, such as monocyte migration to vessel walls, cell adhesion, and angiogenesis, among others. Even though many experimental studies have shown the utility of blocking these receptors or their ligands in the treatment of atherosclerosis, the findings in clinical research are still poor. Thus, in the current review we aimed to describe some promising results concerning the blockade of chemokine receptors as therapeutic targets in the treatment of cardiovascular diseases and also to discuss some challenges that need to be overcome before using these strategies in clinical practice.

Epigenetic regulation of chemokine (CC-motif) ligand 2 in inflammatory diseases

Appropriate responses to inflammation are conducive to pathogen elimination and tissue repair, while uncontrolled inflammatory reactions are likely to result in the damage of tissues. Chemokine (CC-motif) Ligand 2 (CCL2) is the main chemokine and activator of monocytes, macrophages, and neutrophils. CCL2 played a key role in amplifying and accelerating the inflammatory cascade and is closely related to chronic non-controllable inflammation (cirrhosis, neuropathic pain, insulin resistance, atherosclerosis, deforming arthritis, ischemic injury, cancer, etc.). The crucial regulatory roles of CCL2 may provide potential targets for the treatment of inflammatory diseases. Therefore, we presented a review of the regulatory mechanisms of CCL2. Gene expression is largely affected by the state of chromatin. Different epigenetic modifications, including DNA methylation, post-translational modification of histones, histone variants, ATP-dependent chromatin remodelling, and non-coding RNA, could affect the 'open' or 'closed' state of DNA, and then significantly affect the expression of target genes. Since most epigenetic modifications are proven to be reversible, targeting the epigenetic mechanisms of CCL2 is expected to be a promising therapeutic strategy for inflammatory diseases. This review focuses on the epigenetic regulation of CCL2 in inflammatory diseases.

CCL17 Protects Against Viral Myocarditis by Suppressing the Recruitment of Regulatory T Cells

Background Viral myocarditis is characterized by leukocyte infiltration of the heart and cardiomyocyte death. We recently identified C-C chemokine ligand (CCL) 17 as a proinflammatory effector of C-C chemokine receptor 2-positive macrophages and dendritic cells that are recruited to the heart and contribute to adverse left ventricular remodeling following myocardial infarction and pressure overload. Methods and Results Mouse encephalomyocarditis virus was used to investigate the function of CCL17 in a viral myocarditis model. Ccl17^Gfp reporter and knockout mice were used to identify the cell types that express CCL17 and delineate the functional importance of CCL17 in encephalomyocarditis virus clearance and myocardial inflammation. Cardiac CCL17 was expressed in C-C chemokine receptor 2-positive macrophages and dendritic cells following encephalomyocarditis virus infection. Colony-stimulating factor 2 (granulocyte-macrophage colony-stimulating factor) signaling was identified as a key regulator of CCL17 expression. Ccl17 deletion resulted in impaired encephalomyocarditis virus clearance, increased cardiomyocyte death, and higher mortality during infection early stage, and aggravated hypertrophy and fibrotic responses in infection long-term stage. An increased abundance of regulatory T cells was detected in the myocardium of injured Ccl17-deficient mice. Depletion of regulatory T cells in Ccl17-deficient mice abrogated the detrimental role of CCL17 deletion by restoring interferon signaling. Conclusions Collectively, these findings identify CCL17 as an important mediator of the host immune response during cardiac viral infection early stage and suggest that CCL17 targeted therapies should be avoided in acute viral myocarditis.

The role of β-catenin in cardiac diseases

The Wnt/β-catenin signaling pathway is a classical Wnt pathway that regulates the stability and nuclear localization of β-catenin and plays an important role in adult heart development and cardiac tissue homeostasis. In recent years, an increasing number of researchers have implicated the dysregulation of this signaling pathway in a variety of cardiac diseases, such as myocardial infarction, arrhythmias, arrhythmogenic cardiomyopathy, diabetic cardiomyopathies, and myocardial hypertrophy. The morbidity and mortality of cardiac diseases are increasing, which brings great challenges to clinical treatment and seriously affects patient health. Thus, understanding the biological roles of the Wnt/β-catenin pathway in these diseases may be essential for cardiac disease treatment and diagnosis to improve patient quality of life. In this review, we summarize current research on the roles of β-catenin in human cardiac diseases and potential inhibitors of Wnt/β-catenin, which may provide new strategies for cardiac disease therapies.

Identification of GLS as a cuproptosis-related diagnosis gene in acute myocardial infarction

Acute myocardial infarction (AMI) has the characteristics of sudden onset, rapid progression, poor prognosis, and so on. Therefore, it is urgent to identify diagnostic and prognostic biomarkers for it. Cuproptosis is a new form of mitochondrial respiratory-dependent cell death. However, studies are limited on the clinical significance of cuproptosis-related genes (CRGs) in AMI. In this study, we systematically assessed the genetic alterations of CRGs in AMI by bioinformatics approach. The results showed that six CRGs (LIAS, LIPT1, DLAT, PDHB, MTF1, and GLS) were markedly differentially expressed between stable coronary heart disease (stable_CAD) and AMI. Correlation analysis indicated that CRGs were closely correlated with N6-methyladenosine (m6A)-related genes through R language "corrplot" package, especially GLS was positively correlated with FMR1 and MTF1 was negatively correlated with HNRNPA2B1. Immune landscape analysis results revealed that CRGs were closely related to various immune cells, especially GLS was positively correlated with T cells CD4 memory resting and negatively correlated with monocytes. Kaplan-Meier analysis demonstrated that the group with high DLAT expression had a better prognosis. The area under curve (AUC) certified that GLS had good diagnostic value, in the training set (AUC = 0.87) and verification set (ACU = 0.99). Gene set enrichment analysis (GSEA) suggested that GLS was associated with immune- and hypoxia-related pathways. In addition, Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, competing endogenous RNA (ceRNA) analysis, transcription factor (TF), and compound prediction were performed to reveal the regulatory mechanism of CRGs in AMI. Overall, our study can provide additional information for understanding the role of CRGs in AMI, which may provide new insights into the identification of therapeutic targets for AMI.

Potential prognostic biomarkers of sudden cardiac death discovered by machine learning

OBJECTIVE

Sudden cardiac death (SCD) is a serious public health burden. This study aims to find prognostic biomarkers of SCD using machine learning.

METHODS

The myocardial samples from 21 accidental death and 82 sudden death donors were compared to seek for differential genes. Enriched active genes were found according to the PPI interaction network. GSEA analyzed differences in function and pathway between control and experimental groups. Related diseases caused by active genes are mainly exhibited through DO enrichment. Prognostic biomarkers for SCD are identified via two machine learning algorithms. The CIBERSORT method was used to compare the immune microenvironment changes in patients with SCD.

RESULTS

SCD was mainly associated with heart and kidney diseases caused by atherosclerosis. DEFA1B, BGN, SERPINE1, CCL2 and HBB are considered to be prognostic biomarkers for SCD after machine learning. And immune infiltration plays an important role in the process of SCD.

CONCLUSION

We discovered 5 prognostic biomarkers for SCD. And immune microenvironment changes was also found in SCD. Moreover, atherosclerosis might be an important risk factor for SCD.

Inflammatory Glycoprotein YKL-40 Is Elevated after Coronary Artery Bypass Surgery and Correlates with Leukocyte Chemotaxis and Myocardial Injury, a Pilot Study

The aim of the present study was to investigate the levels of YKL-40 during and after coronary artery bypass grafting surgery (CABG) and to establish possible connections between YKL-40 and markers of oxidative stress, inflammation, and myocardial injury. Patients undergoing elective CABG utilizing cardiopulmonary bypass (CPB) were recruited into the study. Blood samples were collected at the onset of anesthesia, during surgery and post-operatively. Levels of YKL-40, 8-isoprostane, interleukin-8 (IL-8), monocyte chemotactic protein-1 (MCP-1) and troponin T (TnT) were measured by immunoassay. YKL-40 levels increased significantly 24 h after CPB. Positive correlation was seen between post-operative TnT and YKL-40 levels (r = 0.457, p = 0.016) and, interestingly, baseline YKL-40 predicted post-operative TnT increase (r = 0.374, p = 0.050). There was also a clear association between YKL-40 and the chemotactic factors MCP-1 (r = 0.440, p = 0.028) and IL-8 (r = 0.484, p = 0.011) linking YKL-40 to cardiac inflammation and fibrosis following CABG. The present results show, for the first time, that YKL-40 is associated with myocardial injury and leukocyte-activating factors following coronary artery bypass surgery. YKL-40 may be a factor and/or biomarker of myocardial inflammation and injury and subsequent fibrosis following heart surgery.

Macrophages in myocardial infarction

The heart contains a population of resident macrophages that markedly expands following injury through recruitment of monocytes and through proliferation of macrophages. In myocardial infarction, macrophages have been implicated in both injurious and reparative responses. In coronary atherosclerotic lesions, macrophages have been implicated in disease progression and in the pathogenesis of plaque rupture. Following myocardial infarction, resident macrophages contribute to initiation and regulation of the inflammatory response. Phagocytosis and efferocytosis are major functions of macrophages during the inflammatory phase of infarct healing, and mediate phenotypic changes, leading to acquisition of an anti-inflammatory macrophage phenotype. Infarct macrophages respond to changes in the cytokine content and extracellular matrix composition of their environment and secrete fibrogenic and angiogenic mediators, playing a central role in repair of the infarcted heart. Macrophages may also play a role in scar maturation and may contribute to chronic adverse remodeling of noninfarcted segments. Single cell studies have revealed a remarkable heterogeneity of macrophage populations in infarcted hearts; however, the relations between transcriptomic profiles and functional properties remain poorly defined. This review manuscript discusses the fate, mechanisms of expansion and activation, and role of macrophages in the infarcted heart. Considering their critical role in injury, repair, and remodeling, macrophages are important, but challenging, targets for therapeutic interventions in myocardial infarction.

lncRNA260 siRNA Accelerates M2 Macrophage Polarization and Alleviates Oxidative Stress via Inhibiting IL28RA Gene Alternative Splicing

The macrophage transformation of inflammatory M1 to anti-inflammatory M2 could be promoted by activating PI3K/AKT signaling pathway. In our previous study, it was found that downregulation of lncRNA260 could ameliorate hypoxic cardiomyocyte injury by regulating IL28RA through the activation of PI3K/AKT signaling pathways. It was suggested that lncRNA260 siRNA could promote the macrophages toward M2 polarization by regulating IL28RA. In this study, lncRNA260 siRNA was used to observe its effect on the polarization of murine bone marrow-derived macrophages (BMDM) and investigate its related mechanisms. lncRNA 260 specific siRNA were designed and synthesized which were transfected into murine BMDM with liposomes. The experiment was divided into three groups: Hypoxia group, Hypoxia+lncRNA 260-specific siRNA transfection group, and Normoxia group. The CD206-APC/CD11b-FITC or CD206-FITC/CD107b (Mac-3) double positive proportions were used to compare the M2 polarization proportions in the hypoxia process by using the immunofluorescence staining method. The p-AKT, Arg 1, PI3KCG, IL28RAV1, and IL28RAV2 protein expression changes were observed by using the western blot method. Compared with the Normoxia group, the M2 proportions were significantly decreased in the Hypoxia group (P < 0.05). Compared with the hypoxia group, the M2 proportions were significantly increased in the Hypoxia+lncRNA260 siRNA transfection group (P < 0.05). In the Hypoxia group, the ratios of Arg 1/β-Actin, p-AKT/β-Actin, PI3KCG/β-Actin, and IL28RAV1/β-Actin were significantly lower than those in the Normoxia group (P < 0.05). After transfection with lncRNA260 siRNA, the ratios of Arg1/β-Actin, p-AKT/β-Actin, PI3KCG/β-Actin, and IL28RAV1/β-Actin were significantly higher than those in the Hypoxia group (P < 0.05). Compared with the Normoxia group, the IL28RAV2/β-Actin in the Hypoxia group was significantly increased (P < 0.05). After transfection with lncRNA260 siRNA, the ratio of IL28RAV2/β-Actin was significantly decreased than that in the Hypoxia group (P < 0.05). lncRNA260 siRNA could promote the M2 polarization of the hypoxia macrophages by reducing the IL28RAV2 alternative splicing variant, which might be related to the activation of the JAK-STAT and PI3K/AKT signaling pathways. It will provide a new strategy for the anti-inflammation, antioxidative stress therapy, and cardiac remodeling after AMI.

Role of the CCL2-CCR2 axis in cardiovascular disease: Pathogenesis and clinical implications

The CCL2-CCR2 axis is one of the major chemokine signaling pathways that has received special attention because of its function in the development and progression of cardiovascular disease. Numerous investigations have been performed over the past decades to explore the function of the CCL2-CCR2 signaling axis in cardiovascular disease. Laboratory data on the CCL2-CCR2 axis for cardiovascular disease have shown satisfactory outcomes, yet its clinical translation remains challenging. In this article, we describe the mechanisms of action of the CCL2-CCR2 axis in the development and evolution of cardiovascular diseases including heart failure, atherosclerosis and coronary atherosclerotic heart disease, hypertension and myocardial disease. Laboratory and clinical data on the use of the CCL2-CCR2 pathway as a targeted therapy for cardiovascular diseases are summarized. The potential of the CCL2-CCR2 axis in the treatment of cardiovascular diseases is explored.

Circulating Monocyte Chemoattractant Protein-1 in Patients with Cardiogenic Shock Complicating Acute Myocardial Infarction Treated with Mild Hypothermia: A Biomarker Substudy of SHOCK-COOL Trial

Background: There is evidence that monocyte chemoattractant protein-1 (MCP-1) levels reflect the intensity of the inflammatory response in patients with cardiogenic shock (CS) complicating acute myocardial infarction (AMI) and have a predictive value for clinical outcomes. However, little is known about the effect of mild therapeutic hypothermia (MTH) on the inflammatory response in patients with CS complicating AMI. Therefore, we conducted a biomarker study to investigate the effect of MTH on MCP-1 levels in patients with CS complicating AMI. Methods: In the randomized mild hypothermia in cardiogenic shock (SHOCK-COOL) trial, 40 patients with CS complicating AMI were enrolled and assigned to MTH (33 °C) for 24 h or normothermia at a 1:1 ratio. Blood samples were collected at predefined time points at the day of admission/day 1, day 2 and day 3. Differences in MCP-1 levels between and within the MTH and normothermia groups were assessed. Additionally, the association of MCP-1 levels with the risk of all-cause mortality at 30 days was analyzed. Missing data were accounted for by multiple imputation as sensitivity analyses. Results: There were differences in MCP-1 levels over time between patients in MTH and normothermia groups (P for interaction = 0.013). MCP-1 levels on day 3 were higher than on day 1 in the MTH group (day 1 vs day 3: 21.2 [interquartile range, 0.25–79.9] vs. 125.7 [interquartile range, 87.3–165.4] pg/mL; p = 0.006) and higher than in the normothermia group at day 3 (MTH 125.7 [interquartile range, 87.3–165.4] vs. normothermia 12.3 [interquartile range, 0–63.9] pg/mL; p = 0.011). Irrespective of therapy, patients with higher levels of MCP-1 at hospitalization tended to have a decreased risk of all-cause mortality at 30 days (HR, 2.61; 95% CI 0.997–6.83; p = 0.051). Conclusions: The cooling phase of MTH had no significant effect on MCP-1 levels in patients with CS complicating AMI compared to normothermic control, whereas MCP-1 levels significantly increased after rewarming. Trial registration: NCT01890317.

Lymphatic endothelial sphingosine 1-phosphate receptor 1 enhances macrophage clearance via lymphatic system following myocardial infarction

Lymphatic endothelial cell homeostasis plays important roles in normal physiological cardiac functions, and its dysfunction significantly influences pathological cardiac remodeling after myocardial infarction (MI). Our results revealed that sphingosine 1-phosphate receptor 1 (S1pr1) expression in cardiac lymphatic endothelial cells (LECs) was sharply changed after MI. It has been shown that S1pr1 tightly controlled LEC functions and homeostasis. We thus hypothesized that lymphatic endothelial S1pr1 might be involved in post-MI cardiac remodeling. We generated LEC-conditional S1pr1 transgenic mice, in which S1pr1 expression was reduced in cardiac LECs. We performed the left anterior descending coronary artery (LAD) ligation operation to induce MI in these mice. Cardiac functions and remodeling were examined by echocardiography analysis and serial histological analysis. Meanwhile, we performed adoptive cell transfer experiments to monitor macrophage trafficking in post-MI myocardium and their draining lymphatic system. Furthermore, in vitro cell culture experiments and mechanism studies were undertaken to uncover the molecular mechanism by which LEC-S1pr1 regulated cardiac inflammation and remodeling after MI. Our results showed that S1pr1 expression significantly decreased in cardiac LECs after MI. Our in vivo experiments showed that the reduced expression of LEC-S1pr1 deteriorated cardiac function and worsened pathological cardiac remodeling after MI. Our further results demonstrated that the reduced expression of LEC-S1pr1 did not influence macrophage infiltration in an early inflammatory phase of MI, but significantly affected macrophages clearance in the later phase of MI via afferent cardiac lymphatics, and thus influenced inflammatory responses and cardiac outcome after MI. Further study showed that S1P/S1pr1 activated ERK signaling pathway and enhanced CCL2 expression, which promoted macrophage trafficking in a paracrine manner. This study reveals that cardiac lymphatic endothelial cells tightly control macrophage trafficking via lymphatic vessels in injured hearts via S1P/S1pr1/ERK/CCL2 pathway and thus regulate post-MI immune modulation and heart repair. This study highlights the importance of cardiac lymphatic vessel system in orchestrating post-MI immune responses and cardiac remodeling by regulating macrophage transit in injured hearts. Our finding implies that a feasible modulation of S1pr1 signaling in LECs might provide a promising target to resolve excessive inflammation and to ameliorate adverse cardiac remodeling after MI.

Intrapericardial Administration of Secretomes from Menstrual Blood-Derived Mesenchymal Stromal Cells: Effects on Immune-Related Genes in a Porcine Model of Myocardial Infarction

Acute myocardial infarction (AMI) is a manifestation of ischemic heart disease where the immune system plays an important role in the re-establishment of homeostasis. We hypothesize that the anti-inflammatory activity of secretomes from menstrual blood-derived mesenchymal stromal cells (S-MenSCs) and IFNγ/TNFα-primed MenSCs (S-MenSCs*) may be considered a therapeutic option for the treatment of AMI. To assess this hypothesis, we have evaluated the effect of S-MenSCs and S-MenSCs* on cardiac function parameters and the involvement of immune-related genes using a porcine model of AMI. Twelve pigs were randomly divided into three biogroups: AMI/Placebo, AMI/S-MenSCs, and AMI/S-MenSCs*. AMI models were generated using a closed chest coronary occlusion-reperfusion procedure and, after 72 h, the different treatments were intrapericardially administered. Cardiac function parameters were monitored by magnetic resonance imaging before and 7 days post-therapy. Transcriptomic analyses in the infarcted tissue identified 571 transcripts associated with the Gene Ontology term Immune response, of which 57 were differentially expressed when different biogroups were compared. Moreover, a prediction of the interactions between differentially expressed genes (DEGs) and miRNAs from secretomes revealed that some DEGs in the infarction area, such as STAT3, IGFR1, or BCL6 could be targeted by previously identified miRNAs in secretomes from MenSCs. In conclusion, the intrapericardial administration of secretome early after infarction has a significant impact on the expression of immune-related genes in the infarcted myocardium. This confirms the immunomodulatory potential of intrapericardially delivered secretomes and opens new therapeutic perspectives in myocardial infarction treatment.

Ultrasound-targeted cationic microbubbles combined with the NFκB binding motif increase SDF-1α gene transfection: A protective role in hearts after myocardial infarction

Treatment of myocardial infarction (MI) remains a major challenge. The chemokine family plays an important role in cardiac injury, repair, and remodeling following MI, while stromal cell-derived factor-1 alpha (SDF-1α) is the most promising therapeutic target. This study aimed to increase SDF-1α expression using a novel gene delivery system and further explore its effect on MI treatment. In this study, two kinds of plasmids, human SDF-1α plasmid (phSDF-1α) and human SDF-1α- nuclear factor κB plasmid (phSDF-1α-NFκB), were constructed and loaded onto cationic microbubble carriers, and the plasmids were released into MI rabbits by ultrasound-targeted microbubble destruction. The transfection efficiency of SDF-1α and the degree of heart repair were further explored and compared. In the MI rabbit models, transfection with phSDF-1α-NFκB resulted in higher SDF-1α expression in peri-infarct area compared with transfection with phSDF-1α or no transfection. Upregulation of SDF-1α was shown beneficial to these MI rabbit models, as demonstrated with better recovery of cardiac function, greater perfusion of the myocardium, more neovascularization, smaller infarction size and thicker infarct wall 1 month after treatment. Ultrasound-targeted cationic microbubbles combined with the NFκB binding motif could increase SDF-1α gene transfection, which would play a protective role after MI.

CCL17 Aggravates Myocardial Injury by Suppressing Recruitment of Regulatory T Cells

BACKGROUND

Recent studies have established that CCR2 (C-C chemokine receptor type 2) marks proinflammatory subsets of monocytes, macrophages, and dendritic cells that contribute to adverse left ventricle (LV) remodeling and heart failure progression. Elucidation of the effector mechanisms that mediate adverse effects of CCR2+ monocytes, macrophages, and dendritic cells will yield important insights into therapeutic strategies to suppress myocardial inflammation.

METHODS

We used mouse models of reperfused myocardial infarction, angiotensin II and phenylephrine infusion, and diphtheria toxin cardiomyocyte ablation to investigate CCL17 (C-C chemokine ligand 17). We used Ccl17 knockout mice, flow cytometry, RNA sequencing, biochemical assays, cell trafficking studies, and in vivo cell depletion to identify the cell types that generate CCL17, define signaling pathways that controlled its expression, delineate the functional importance of CCL17 in adverse LV remodeling and heart failure progression, and determine the mechanistic basis by which CCL17 exerts its effects.

RESULTS

We demonstrated that CCL17 is expressed in CCR2+ macrophages and cluster of differentiation 11b+ conventional dendritic cells after myocardial infarction, angiotensin II and phenylephrine infusion, and diphtheria toxin cardiomyocyte ablation. We clarified the transcriptional signature of CCL17+ macrophages and dendritic cells and identified granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling as a key regulator of CCL17 expression through cooperative activation of STAT5 (signal transducer and activator of transcription 5) and canonical NF-κB (nuclear factor κ-light-chain-enhancer of activated B cells) signaling. Ccl17 deletion resulted in reduced LV remodeling, decreased myocardial fibrosis and cardiomyocyte hypertrophy, and improved LV systolic function after myocardial infarction and angiotensin II and phenylephrine infusion. We observed increased abundance of regulatory T cells (Tregs) in the myocardium of injured Ccl17 knockout mice. CCL17 inhibited Treg recruitment through biased activation of CCR4. CCL17 activated Gq signaling and CCL22 (C-C chemokine ligand 22) activated both Gq and ARRB (β-arrestin) signaling downstream of CCR4. CCL17 competitively inhibited CCL22 stimulated ARRB signaling and Treg migration. We provide evidence that Tregs mediated the protective effects of Ccl17 deletion on myocardial inflammation and adverse LV remodeling.

CONCLUSIONS

These findings identify CCL17 as a proinflammatory mediator of CCR2+ macrophages and dendritic cells and suggest that inhibition of CCL17 may serve as an effective strategy to promote Treg recruitment and suppress myocardial inflammation.

Qishen granule (QSG) exerts cardioprotective effects by inhibiting NLRP3 inflammasome and pyroptosis in myocardial infarction rats

ETHNOPHARMACOLOGICAL RELEVANCE

Qishen granule (QSG) is a traditional Chinese medicine formulation that is widely used in clinical practice for the treatment of myocardial infarction (MI), and its efficacy and safety have been well approved. However, the underlying mechanism by which QSG alleviates inflammation and cell pyroptosis remains unknown.

AIM OF THE STUDY

The aim of this study was to clarify whether QSG ameliorated MI by inhibiting inflammasome activation and cell pyroptosis.

MATERIALS AND METHODS

In vivo, SD male rats were subjected to the left anterior ascending branch (LAD) ligation to construct MI model. And in vitro, OGD/R, ISO, Ang II and LPS-ATP were used to induce H9C2 cell injury. Cell viability and ROS were detected by CCK8 and DCFH-DA dye respectively. Western blots were applied to detect the expression of inflammasome-related proteins. Cell pyroptosis was evaluated by Calcein-AM/PI staining, Hoechst/PI staining and NT-GSDMD expression.

RESULTS

QSG administration improved the cardiac function, as well as reduced inflammatory cell infiltration and collagen deposition. In H9C2 cells, OGD/R failed to induce inflammasome activation, while ISO, Ang II and LPS-ATP successfully induced inflammasome activation and cell pyroptosis, as evidenced by increased Caspase-1(P20) and NT-GSDMD. In LPS-ATP induced H9C2 model, ROS production and cell pyroptosis were suppressed when treated with QSG. Furthermore, QSG significantly decreased the protein levels of P65-NF-κB, NLRP3, ASC, Caspase-1 (P20), Cleaved IL-18, Cleaved IL-1β and NT-GSDMD.

CONCLUSION

This study is the first to demonstrate that QSG has cardioprotective effects by inhibiting inflammasome activation and pyroptosis, which are considered as promising therapeutic targets for MI.

A 3D Mathematical Model of Coupled Stem Cell-Nutrient Dynamics in Myocardial Regeneration Therapy

Stem cell therapy is a promising treatment for the regeneration of myocardial tissue injured by an ischemic event. Mathematical modeling of myocardial regeneration via stem cell therapy is a challenging task, since the mechanisms underlying the processes involved in the treatment are not yet fully understood. Many aspects must be accounted for, such as the spread of stem cells and nutrients, chemoattraction, cell proliferation, stages of cell maturation, differentiation, angiogenesis, stochastic effects, just to name a few. In this paper we propose a 3D mathematical model with a free boundary that aims to provide a qualitative description of some main aspects of the stem cell regenerative therapy in a simplified scenario. The paper mainly focuses on the description of the shrinking of the necrotic core during treatment. The stem cell and nutrients dynamics are described through coupled reaction-diffusion problems. Proliferation, chemoattraction, tissue regeneration and nutrient consumption are included in the model.

Secretome of Stressed Peripheral Blood Mononuclear Cells Alters Transcriptome Signature in Heart, Liver, and Spleen after an Experimental Acute Myocardial Infarction: An In Silico Analysis

Simple Summary

Acute myocardial infarction is characterized by impaired coronary blood flow, which leads to cardiac ischemia and, ultimately, compromised heart function. Damage and cellular responses are not limited to the non-perfused area, but rather affect the entire heart, as well as distal organs, such as the liver and spleen. We found that the therapeutic secretome of stressed white blood cells improved short-term and long-term cardiac performance in a porcine infarction model. In order to unravel the molecular events governing secretome-mediated tissue regeneration, we performed transcriptional analyses of the non-perfused, transition, and perfused heart, as well as the liver and spleen 24 h after myocardial infarction. We observed a highly tissue-specific effect of the secretome and, except for the transition zone, a uniform downregulation of pro-inflammatory factors and pathways. Simultaneously, the secretome strongly promoted the expression of genes that are essential for heart function in the non-perfused area. In the liver and spleen, different metabolic processes were induced. Together, our data suggest several plausible mechanisms by which the secretome improves heart function after cardiac ischemia. Deepening our understanding of the molecular processes identified here might uncover further pharmacologic strategies aiming at delimiting adverse cardiac remodeling and sequelae after myocardial infarction.

Abstract

Acute myocardial infarction (AMI) is a result of cardiac non-perfusion and leads to cardiomyocyte necrosis, inflammation, and compromised cardiac performance. Here, we showed that the secretome of γ-irradiated peripheral blood mononuclear cells (PBMCsec) improved heart function in a porcine AMI model and displayed beneficial long- and short-term effects. As an AMI is known to strongly affect gene regulation of the ischemia non-affected heart muscle and distal organs, we employed a transcriptomics approach to further study the immediate molecular events orchestrated using the PBMCsec in myocardium, liver, and spleen 24 h post ischemia. In the infarcted area, the PBMCsec mainly induced genes that were essential for cardiomyocyte function and simultaneously downregulated pro-inflammatory genes. Interestingly, genes associated with pro-inflammatory processes were activated in the transition zone, while being downregulated in the remote zone. In the liver, we observed a pronounced inhibition of immune responses using the PBMCsec, while genes involved in urea and tricarboxylic cycles were induced. The spleen displayed elevated lipid metabolism and reduced immunological processes. Together, our study suggested several types of pharmacodynamics by which the PBMCsec conferred immediate cardioprotection. Furthermore, our data supported the assumption that an AMI significantly affects distal organs, suggesting that a holistic treatment of an AMI, as achieved by PBMCsec, might be highly beneficial.

Resuscitating the Field of Cardiac Regeneration: Seeking Answers from Basic Biology

Heart failure (HF) is one of the leading causes for hospital admissions worldwide. HF patients are classified based on the chronic changes in left ventricular ejection fraction (LVEF) as preserved (LVEF ≥ 50%), reduced (LVEF ≤ 40%), or mid-ranged (40% < LVEF < 50%) HFs. Treatments nowadays can prevent HFrEF progress, whereas only a few of the treatments have been proven to be effective in improving the survival of HFpEF. In this review, numerous mediators involved in the pathogenesis of HF are summarized. The regional upstream signaling and their diagnostic and therapeutic potential are also discussed. Additionally, the recent challenges and development in cardiac regenerative therapy that hold opportunities for future research and clinical translation are discussed.

The Preventive Effect of Cardiac Sympathetic Denervation Induced by 6-OHDA on Myocardial Ischemia-Reperfusion Injury: The Changes of lncRNA/circRNAs-miRNA-mRNA Network of the Upper Thoracic Spinal Cord in Rats

In this study, we investigated whether chemical 6-hydroxydopamine (6-OHDA) stimuli caused cardiac sympathetic denervation (SD), and we analyzed gene expression profiles to determine the changes in the lncRNA/circRNAs-miRNA-mRNA network in the affected spinal cord segments to identify putative target genes and molecular pathways in rats with myocardial ischemia–reperfusion injury (MIRI). Our results showed that cardiac sympathetic denervation induced by 6-OHDA alleviated MIRI. Compared with the ischemia reperfusion (IR, MIRI model) group, there were 148 upregulated and 51 downregulated mRNAs, 165 upregulated and 168 downregulated lncRNAs, 70 upregulated and 52 downregulated circRNAs, and 12 upregulated and 11 downregulated miRNAs in the upper thoracic spinal cord of the SD-IR group. Furthermore, we found that the differential genes related to cellular components were mainly enriched in extracellular and cortical cytoskeleton, and molecular functions were mainly enriched in chemokine activity. Pathway analysis showed that the differentially expressed genes were mainly related to the interaction of cytokines and cytokine receptors, sodium ion reabsorption, cysteine and methionine metabolism, mucoglycan biosynthesis, cGMP-PKG signaling pathway, and MAPK signaling pathway. In conclusion, the lncRNA/circRNAs-miRNA-mRNA networks in the upper thoracic spinal cord play an important role in the preventive effect of cardiac sympathetic denervation induced by 6-OHDA on MIRI, which offers new insights into the pathogenesis of MIRI and provides new targets for MIRI.

Guidelines for in vivo mouse models of myocardial infarction

Despite significant improvements in reperfusion strategies, acute coronary syndromes all too often culminate in a myocardial infarction (MI). The consequent MI can, in turn, lead to remodeling of the left ventricle (LV), the development of LV dysfunction, and ultimately progression to heart failure (HF). Accordingly, an improved understanding of the underlying mechanisms of MI remodeling and progression to HF is necessary. One common approach to examine MI pathology is with murine models that recapitulate components of the clinical context of acute coronary syndrome and subsequent MI. We evaluated the different approaches used to produce MI in mouse models and identified opportunities to consolidate methods, recognizing that reperfused and nonreperfused MI yield different responses. The overall goal in compiling this consensus statement is to unify best practices regarding mouse MI models to improve interpretation and allow comparative examination across studies and laboratories. These guidelines will help to establish rigor and reproducibility and provide increased potential for clinical translation.

Impact of COVID-19 infection on the cardiovascular system: An evidence-based analysis of risk factors and outcomes

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as COVID-19, emerged in late 2019 in Wuhan, China. The World Health Organization declared the virus a pandemic on March 11, 2020. Disease progression from COVID-19 infection has shown significant symptom manifestations within organ systems beyond the respiratory system. The literature has shown increasing evidence of cardiovascular involvement during disease course and an associated increase in mortality among infected patients. Although the understanding of this novel virus is continually evolving, it is currently proposed that the mechanism by which the SARS-CoV-2 virus contributes to cardiovascular manifestations involves the ACE2 transmembrane protein. The protein ACE2 is highly expressed in blood vessel pericytes, and infection can result in microvascular dysfunction and subsequent acute coronary syndromes. Complications involving the cardiovascular system include myocardial infarction, arrhythmias, shock, and heart failure. In this evidence-based review, we discuss risk factors of cardiovascular involvement in COVID-19 infection, pathophysiology of COVID-19-related cardiovascular infection, and injury, COVID-19 effects on the cardiovascular system and corresponding treatments, and hematologic effects of COVID-19 and COVID-19 in heart transplant patients. Clinicians managing COVID-19 patients should appreciate the potential cardiovascular effects related to the disease process.

Histamine is involved in the regulation of collagen content in cultured heart myofibroblasts via H2, H3 and H4 histamine receptors

Histamine is involved in the regulation of collagen metabolism during healing following a myocardial infarction; however, its effects on the intact heart tissue is unknown. The aim of the present study was to determine whether histamine may influence collagen content in cells isolated from intact heart, and to identify the histamine receptor involved in the regulation of collagen deposition. Cells were isolated from intact rat hearts and subjected to identification by flow cytometry. The effects of histamine and its receptor agonists and antagonists were investigated. The heart cells were found to be actin, desmin and vimentin positive. Histamine (used at a concentrations of 1x10-10-1x10-5 M) increased collagen content within the culture and increased the expression of α1 chain of the procollagen type III gene. The H2, H3 and H4 receptor inhibitors ranitidine, ciproxifan and JNJ 7777120 blocked the effect of histamine on collagen content. All tested histamine receptor agonists, viz. 2-pyridylethylamine dihydrochloride (H1 receptor agonist), amthamine dihydrobromide (H2 receptor agonist), imetit (H3 receptor agonist) and 4-methylhistamine hydrochloride (H4 receptor agonist), elevated collagen content within the heart myofibroblast cultures. The cells isolated from the intact heart were identified as myofibroblasts. Thus, the results of the present study showed that histamine augmented collagen content in the heart myofibroblast culture by activation of three histamine receptors (H2, H3 and H4). The effect of the amine was also dependent on the activation of collagen type III gene expression.