Regulatory T lymphocytes in myocardial infarction: A promising new therapeutic target

Regulatory T cells as a therapeutic target in acute myocardial infarction

Acute myocardial infarction (AMI), mainly triggered by vascular occlusion or thrombosis, is the most prevalent cause of morbidity and mortality among all cardiovascular diseases. The devastating consequences of AMI are further aggravated by the intricate cellular processes involved in inflammation. In the past two decades, many studies have reported that regulatory T cells (Tregs), as the main immunoregulatory cells, play a crucial role in AMI progression. This review offers a comprehensive insight into the intricate relationship between Tregs and AMI development. Moreover, it explores emerging therapeutic strategies that focus on Tregs and their exosomes. Furthermore, we underscore the importance of employing noninvasive in vivo imaging techniques to advance the clinical applications of Tregs-based treatments in AMI. Although further research is essential to fully elucidate the molecular mechanisms underlying the effects of Tregs, therapies tailored to these cells hold immense potential for the treatment of patients with AMI.

Overview of multifunctional Tregs in cardiovascular disease: From insights into cellular functions to clinical implications

Regulatory T cells (Tregs) are crucial in regulating T-cell-mediated immune responses. Numerous studies have shown that dysfunction or decreased numbers of Tregs may be involved in inflammatory cardiovascular diseases (CVDs) such as atherosclerosis, hypertension, myocardial infarction, myocarditis, cardiomyopathy, valvular heart diseases, heart failure, and abdominal aortic aneurysm. Tregs can help to ameliorate CVDs by suppressing excessive inflammation through various mechanisms, including inhibition of T cells and B cells, inhibition of macrophage-induced inflammation, inhibition of dendritic cells and foam cell formation, and induction of anti-inflammatory macrophages. Enhancing or restoring the immunosuppressive activity of Tregs may thus serve as a fundamental immunotherapy to treat hypertension and CVDs. However, the precise molecular mechanisms underlying the Tregs-induced protection against hypertension and CVDs remain to be investigated. This review focuses on recent advances in our understanding of Tregs subsets and function in CVDs. In addition, we discuss promising strategies for using Tregs through various pharmacological approaches to treat hypertension and CVDs.

Neutrophil to lymphocyte ratio as a prognostic marker for cardiovascular outcomes in patients with ST-segment elevation myocardial infarction after percutaneous coronary intervention: A systematic review and meta-analysis

BACKGROUND

Neutrophil to lymphocyte ratio (NLR) has been considered a prognostic biomarker of mortality and other major cardiac events. This study investigates NLR's efficacy in predicting in-hospital and long-term outcomes in patients with ST-segment elevated myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI).

METHODS

Electronic databases (PUBMED, Cochrane CENTRAL, ERIC, Embase, Ovid, and Google Scholar) were searched till June 2022 to identify studies having STEMI patients who underwent PCI. Risk ratios and mean differences (MDs), along with their corresponding 95% confidence intervals (Cis) and standard deviations (SDs), were pooled using a random-effect model. This meta-analysis has been registered on Prospero (ID: CRD42022344072).

RESULTS

A total of 35 studies with 28,756 patients were included. Pooled estimates revealed an increased incidence of primary outcomes; in-hospital all-cause mortality (RR = 3.52; 95% CI = 2.93-4.24), long-term all-cause mortality (HR = 1.07; 95% CI = 1.00-1.14), (RR = 3.32; 95% CI = 2.57-4.30); in-hospital cardiovascular mortality (RR = 2.66; 95% CI = 2.04-3.48), long-term cardiovascular mortality (RR = 6.67; 95% CI = 4.06-10.95); in-hospital major adverse cardiovascular events (MACE) (RR = 1.31; 95% CI = 1.17-1.46), long-term MACE (RR = 2.92; 95% CI = 2.16-3.94); length of hospital stay (WMD = 0.60 days; 95% CI = 0.40-0.79) in patients with high NLR compared to those with a low NLR.

CONCLUSION

NLR might be a valuable tool for prognostication (in-hospital) and stratification of patients with STEMI who underwent PCI.

ROS-responsive drug-releasing injectable microgels for ameliorating myocardial infarction

Despite of the recent advances in regulatory T cell (Treg) therapy, a limited number of available cells and specificity at the desired tissue site have severely compromised their efficacy. Herein, an injectable drug-releasing (MTK-TK-drug) microgel system in response to in situ stimulation by reactive oxygen species (ROS) was constructed with a coaxial capillary microfluidic system and UV curing. The spherical microgels with a size of 150 μm were obtained. The MTK-TK-drug microgels efficiently converted the pro-inflammatory Th17 cells into anti-inflammatory regulatory T cells (Treg) cells in vitro, and the ROS-scavenging materials synergistically enhanced the effect by modulating the inflammation microenvironment. Thus, the microgels significantly reduced cardiomyocyte apoptosis and decreased the inflammatory response in the early stages of post-myocardial infarction (MI) in vivo, thereby reducing fibrosis, promoting vascularization, and preserving cardiac function. Overall, our results indicate that the MTK-TK-drug microgels can attenuate the inflammatory response and improve MI therapeutic effects in vivo.

Characterizing the immune response to myocardial infarction in pigs

Though myocardial infarction (MI) in pigs is a well-established translational large animal model, it has not yet been widely used for immunotherapy studies, and a comprehensive description of the immune response to MI in this species is lacking. We induced MI in Landrace pigs by balloon occlusion of the left anterior descending artery over 90 min. Within 14 days, the necrotic myocardium was progressively replaced by scar tissue with involvement of myofibroblasts. We characterized the immune response in the heart ex vivo by (immuno)histology, flow cytometry, and RNA sequencing of myocardial tissue on days 3, 7, and 14 after MI. Besides a clear predominance of myeloid cells among heart-infiltrating leukocytes, we detected activated T cells and an increasing proportion of CD4+ Foxp3+ regulatory T cells (Treg), especially in the infarct core-findings that closely mirror what has been observed in mice and humans after MI. Transcriptome data indicated inflammatory activity that was persistent but markedly changing in character over time and linked to extracellular matrix biology. Analysis of lymphocytes in heart-draining lymph nodes revealed significantly higher proliferation rates of T helper cell subsets, including Treg on day 7 after MI, compared to sham controls. Elevated frequencies of myeloid progenitors in the spleen suggest that it might be a site of emergency myelopoiesis after MI in pigs, as previously shown in mice. We thus provide a first description of the immune response to MI in pigs, and our results can aid future research using the species for preclinical immunotherapy studies.

Regulatory T-cell frequency and function in acute myocardial infarction patients and its correlation with ventricular dysfunction

A high percentage of patients with acute coronary syndrome develop heart failure due to the ischemic event. Regulatory T (Treg) cells are lymphocytes with suppressive capacity that control the immune response and include the conventional CD4+ CD25hi Foxp3+ cells and the CD4+ CD25var CD69+ LAP+ Foxp3- IL-10+ cells. No human follow-up studies focus on Treg cells' behavior after infarction and their possible relationship with ventricular function as a sign of postischemic cardiac remodeling. This study aimed to analyze, by flow cytometry, the circulating levels of CD69+ Treg cells and CD4+ CD25hi Foxp3+ cells, their IL-10+ production as well as their function in patients with acute myocardial infarction (AMI), and its possible relation with ventricular dysfunction. We found a significant difference in the percentage of CD4+ CD25hi Foxp3+ cells and IL-10+ MFI in patients with AMI at 72 hours compared with the healthy control group, and the levels of these cells were reduced 6 months post-AMI. Regarding the suppressive function of CD4+ CD25+ regulatory cells, they were dysfunctional at 3 and 6 months post-AMI. The frequency of CD69+ Treg cells was similar between patients with AMI at 72 hours postinfarction and the control groups. Moreover, the frequency of CD69+ Treg cells at 3 and 6 months postischemic event did not vary over time. Treg cells play a role in regulating inflammation after an AMI, and its function may be compromised in this pathology. This work is the first report to evaluate CD69+ Foxp3- Treg cells in AMI patients.

Understanding the Role of Galectin-1 in Heart Failure: A Comprehensive Narrative Review

Heart failure (HF) is the fastest-growing cardiovascular condition worldwide. The immune system may play a role in the development of HF since this condition is associated with elevated pro-inflammatory cytokine levels. HF is a life-threatening disease, and there is an increasing demand for diagnostic biomarkers, prognostic factors, and therapeutic agents that can help treat it. Galectin-1 (Gal-1) is the prototype galectin of the lectin family. Multiple signal transduction pathways are regulated by Ras proteins, which act as a molecular switch in cells. Gal-1 regulates T and B cell activation, differentiation, and survival. Gal-1 has been linked to inflammation. Activated T cells produce Gal-1 through an autocrine apoptotic mechanism involving MEK1/ERK and p38 MAPK. In the cardiovascular system, atherosclerosis is facilitated by Gal-1. Heart disease, myocardial infarction, hypertension, and stroke can be caused by atherosclerotic plaque. HF and heart hypertrophy are caused by decreased cardiac L-type Ca2+ channel activity. Deregulation of Gal-1 and CaV1.2 in pathological cardiac hypertrophy suggests a possible target for anti-hypertrophic therapy. Rat hypertrophic cardiomyocytes express Gal-1 and CaV1.2 channels simultaneously. It has been reported that diastolic dysfunction (DD) is associated with elevated Gal-1 levels. The high Gal-1 level in subjects led to the lowest cumulative survival as a composite endpoint. Incidences of HF, DD, and serum Gal-1 levels correlated significantly. The ejection fraction was negatively correlated with Gal-1 and CRP concentrations. Based on two different approaches in mice and humans, Gal-1 was identified as a potential mediator of HF.

The relationship between C-reactive protein to lymphocyte ratio and the prevalence of myocardial infarction in US adults: A cross-sectional study

Objective

C-reactive protein to lymphocyte ratio (CLR) has been identified as a novel inflammatory biomarker. However, the role of CLR in myocardial infarction is unclear. Thus, this study designs to investigate the association of CLR with the prevalence of myocardial infarction in a large multiracial population in the United States.

Methods

Participants from the National Health and Nutrition Examination Survey (NHANES) 2017-March 2020 Pre-pandemic were included in this cross-sectional study. Multivariable regression and subgroup analyses, controlling for demographic variables, were performed to examine the association between CLR and its quintiles and myocardial infarction. A smooth curve fitting was used to model the non-linear relationship between them.

Results

A total of 12,615 participants aged ≥18 years were recruited, of whom 609 (4.83%) self-reported a history of myocardial infarction. Compared to those in the lowest quartile of ln-transformed CLR (Q1), the myocardial infarction risks for subjects in Q2, Q3, and Q4 were 1.64, 1.71, and 1.79 times, respectively. Obvious upward trends were observed when ln-transformed CLR increased (P for trend <0.01). In continuous analyses, the fully adjusted odds ratios (OR) for myocardial infarction prevalence per ln-transformed increment in CLR was 1.46 (95% CI: 1.16-1.84, P < 0.01). Furthermore, a linear association was detected for ln-transformed CLR with the risk of myocardial infarction. Interaction test showed that the effect of CLR on myocardial infarction was significantly affected by age (P for interaction = 0.04).

Conclusions

Data from a large, cross-sectional cohort program show that CLR is positively associated with myocardial infarction prevalence. Our findings highlight that CLR may be a novel inflammation warning biomarker for myocardial infarction.

The Role of Regulatory T Cells in Heart Repair After Myocardial Infarction

Myocardial infarction (MI) remains one of the leading causes of death worldwide. Inflammation and immune responses after MI are of significance to the adverse cardiac remodeling. Regulatory T cells (Tregs) play an important role in suppressing the immune response and thus benefit the post-MI remodeling. After MI, damaged cardiomyocytes may be replaced by scar tissue, leading to systolic and diastolic dysfunction and subsequently adverse remodeling. In this review, we provide an overview of the function and possible mechanisms of Tregs in post-MI heart repair. Specifically, after the occurrence of MI, Tregs infiltrated to peri-infarcted myocardium through CCR5 pathway, CXCR4-CXCL12 axis, and Hippo pathway. Normal functional Tregs can reduce the size of the MI area, improve heart function, and ameliorate myocardial remodeling by inhibiting proinflammatory cells accumulation, changing the proportion of macrophages phenotypes, improving myocardial fibrosis, protecting myocardial cells, and promoting angiogenesis. Eventually, Functional Tregs recruited into the heart can improve MI outcomes. Therefore, targeted therapies with Tregs might provide a promising approach to the treatment of MI remodeling.

Myocardial ischemia-reperfusion injury; Molecular mechanisms and prevention

Cardiovascular diseases are one of the leading causes of mortality in developed countries. Among cardiovascular disorders, myocardial infarction remains a life-threatening problem predisposing to the development and progression of ischemic heart failure. Ischemia/reperfusion (I/R) injury is a critical cause of myocardial injury. In recent decades, many efforts have been made to find the molecular and cellular mechanisms underlying the development of myocardial I/R injury and post-ischemic remodeling. Some of these mechanisms are mitochondrial dysfunction, metabolic alterations, inflammation, high production of ROS, and autophagy deregulation. Despite continuous efforts, myocardial I/R injury remains a major challenge in medical treatments of thrombolytic therapy, heart disease, primary percutaneous coronary intervention, and coronary arterial bypass grafting. The development of effective therapeutic strategies to reduce or prevent myocardial I/R injury is of great clinical significance.

Bioinformatics and experimental analyses of glutamate receptor and its targets genes in myocardial and cerebral ischemia

BACKGROUND

There is a mutual hemodynamic and pathophysiological basis between the heart and brain. Glutamate (GLU) signaling plays an important role in the process of myocardial ischemia (MI) and ischemic stroke (IS). To further explore the common protective mechanism after cardiac and cerebral ischemic injuries, the relationship between GLU receptor-related genes and MI and IS were analyzed.

RESULTS

A total of 25 crosstalk genes were identified, which were mainly enriched in the Toll-like receptor signaling pathway, Th17 cell differentiation, and other signaling pathways. Protein-protein interaction analysis suggested that the top six genes with the most interactions with shared genes were IL6, TLR4, IL1B, SRC, TLR2, and CCL2. Immune infiltration analysis suggested that immune cells such as myeloid-derived suppressor cells and monocytes were highly expressed in the MI and IS data. Memory B cells and Th17 cells were expressed at low levels in the MI and IS data; molecular interaction network construction suggested that genes such as JUN, FOS, and PPARA were shared genes and transcription factors; FCGR2A was a shared gene of MI and IS as well as an immune gene. Least absolute shrinkage and selection operator logistic regression analysis identified nine hub genes: IL1B, FOS, JUN, FCGR2A, IL6, AKT1, DRD4, GLUD2, and SRC. Receiver operating characteristic analysis revealed that the area under the curve of these hub genes was > 65% in MI and IS for all seven genes except IL6 and DRD4. Furthermore, clinical blood samples and cellular models showed that the expression of relevant hub genes was consistent with the bioinformatics analysis.

CONCLUSIONS

In this study, we found that the GLU receptor-related genes IL1B, FOS, JUN, FCGR2A, and SRC were expressed in MI and IS with the same trend, which can be used to predict the occurrence of cardiac and cerebral ischemic diseases and provide reliable biomarkers to further explore the co-protective mechanism after cardiac and cerebral ischemic injury.

The role of major immune cells in myocardial infarction

Myocardial infarction (MI) is a cardiovascular disease (CVD) with high morbidity and mortality worldwide, often leading to adverse cardiac remodeling and heart failure, which is a serious threat to human life and health. The immune system makes an important contribution to the maintenance of normal cardiac function. In the disease process of MI, necrotic cardiomyocytes release signals that activate nonspecific immunity and trigger the action of specific immunity. Complex immune cells play an important role in all stages of MI progression by removing necrotic cardiomyocytes and tissue and promoting the healing of damaged tissue cells. With the development of biomaterials, cardiac patches have become an emerging method of repairing MI, and the development of engineered cardiac patches through the construction of multiple animal models of MI can help treat MI. This review introduces immune cells involved in the development of MI, summarizes the commonly used animal models of MI and the newly developed cardiac patch, so as to provide scientific reference for the accurate diagnosis and effective treatment of MI.

The mechanistic role of neutrophil lymphocyte ratio perturbations in the leading non communicable lifestyle diseases

Inflammation plays a critical role in the development and progression of chronic diseases like type 2 diabetes mellitus, coronary artery disease, and chronic obstructive pulmonary disease. Inflammatory responses are indispensable for pathogen control and tissue repair, but they also cause collateral damage. A chronically activated immune system and the resultant immune dysregulation mediated inflammatory surge may cause multiple negative effects, requiring tight regulation and dampening of the immune response to minimize host injury.  While chronic diseases are characterized by systemic inflammation, the mechanistic relationship of neutrophils and lymphocytes to inflammation and its correlation with the clinical outcomes is yet to be elucidated. The neutrophil to lymphocyte ratio (NLR) is an easy-to-measure laboratory marker used to assess systemic inflammation. Understanding the mechanisms of NLR perturbations in chronic diseases is crucial for risk stratification, early intervention, and finding novel therapeutic targets. We investigated the correlation between NLR and prevalent chronic conditions as a measure of systemic inflammation. In addition to predicting the risk of impending chronic conditions, NLR may also provide insight into their progression. This review summarizes the mechanisms of NLR perturbations at cellular and molecular levels, and the key inflammatory signaling pathways involved in the progression of chronic diseases. We have also explored preclinical studies investigating these pathways and the effect of quelling inflammation in chronic disease as reported by a few in vitro, in vivo studies, and clinical trials.

Identification of potential biomarkers and immune-related pathways related to immune infiltration in patients with acute myocardial infarction

BACKGROUND

Acute myocardial infarction (AMI), a medical condition caused by the ischemic necrosis of cardiac tissues, is due to sudden occlusion of the coronary arteries in patients including transplant recipients. It is the leading reason for death and disability worldwide. This study aimed to search potential biomarkers related to the progression of AMI and identify the related immune-related pathways, as also examine their association with the immune cell infiltration and diagnostic value for AMI.

METHODS

Datasets of gene microarray were extracted from (www.ncbi.nlm.nih.gov/geo) the Gene Expression Omnibus (GEO) database and AMI-related biomarkers were obtained by differential expression analysis and weighted correlation network analysis (WGCNA). Subsequently, the support vector machine-recursive feature elimination (SVM-RFE) and the least absolute shrinkage and selection operator (LASSO) regression analyses were used to mine AIM-related hub markers. For the assessment of the diagnostic value of these markers for AMI, the receiver operator characteristic (ROC) curves were plotted. Additionally, the single-sample gene set enrichment analysis (ssGSEA) was performed to determine the immune cell infiltration.

RESULTS

A total of 1273 differentially expressed genes (DEGs) were obtained. Nine co-expression modules were obtained after WGCNA. Among them, the brown-colored module was identified as the hub for AMI (correlation [cor] = 0.73, P = 1.1e-87), and intersected with the DEGs yielded a total of 88 shared genes. Subsequently, five hub genes were obtained from the analysis of the LASSO regression and SVM-RFE algorithm. Ultimately, using the ROC curves, the diagnostic values of these genes for AMI were confirmed. The five hub genes were also found to be significantly associated with the infiltration levels of multiple immune cells. Moreover, the DEGs were mainly enriched in the inflammatory and immune-related gene sets evidenced by the functional enrichment analysis.

CONCLUSION

The five hub genes may serve as potential markers for AMI diagnosis and the findings have implications for further investigations on the molecular mechanisms underlying AMI.

The Role of Immune Cells in Cardiac Remodeling After Myocardial Infarction

Myocardial infarction (MI) is an irreversible damage of the heart muscle, which often leads to adverse cardiac remodeling and progressive heart failure. After MI, immune cells play a vital role in the clearance of the dying tissue and cardiac remodeling. Post-MI events include the release of danger signals by necrotic cardiomyocytes and the migration of the inflammatory cells, such as dendritic cells, neutrophils, monocytes, and macrophages, into the site of the cardiac injury to digest the cell debris and secrete a variety of inflammatory factors activating the inflammatory response. In this review, we focus on the role of immune cells in the cardiac remodeling after MI and the novel immunotherapies targeting immune cells.

Platelet-to-Lymphocyte Ratio at Admission as a Predictor of In-Hospital and Long-Term Outcomes in Patients With ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: A Systematic Review and Meta-Analysis

Background

ST-segment elevation myocardial infarction (STEMI) is the most severe form of acute coronary syndrome (ACS) which is associated with significant adverse outcomes. Platelet-to-lymphocyte ratio (PLR) is a novel inflammatory biomarker that has been used as a predictor of various cardiovascular diseases, including ACS. This meta-analysis aimed to investigate the prognostic value of PLR as a predictor of in-hospital and long-term outcomes in patients with STEMI undergoing primary percutaneous coronary intervention (PCI).

Methods

We performed a comprehensive systematic literature search in the databases of PubMed, ScienceDirect, Cochrane Library, and ProQuest for eligible studies. The primary outcomes were major adverse cardiac events (MACEs) and mortality, both in-hospital and long-term follow-up. The outcomes were compared between patients with high and low admission PLR. The quality assessment was conducted using the Newcastle-Ottawa scale. Review Manager 5.3 was used to perform the meta-analysis.

Results

Six cohort studies involving 4,289 STEMI patients undergoing primary PCI were included in this meta-analysis. The pooled analysis showed that a high PLR at admission was associated with increased in-hospital MACE (odds ratio (OR) = 1.94, 95% confidence interval (CI) = 1.56 - 2.40, P < 0.00001, I² = 45%) and in-hospital mortality (OR = 2.07; 95% CI = 1.53 - 2.80; P < 0.00001; I² = 50%), as well as increased long-term MACE (OR = 1.98; 95% CI = 1.31 - 3.00; P = 0.001; I² = 72%) and long-term mortality (OR = 2.79; 95% CI = 1.45 - 5.36; P = 0.002; I² = 83%).

Conclusions

In patients with STEMI undergoing primary PCI, a high PLR at admission predicts in-hospital MACE and mortality along with long-term MACE and mortality.

Healing the Broken Heart; The Immunomodulatory Effects of Stem Cell Therapy

Cardiovascular Disease (CVD) is a leading cause of mortality within the United States. Current treatments being administered to patients who suffered a myocardial infarction (MI) have increased patient survival, but do not facilitate the replacement of damaged myocardium. Recent studies demonstrate that stem cell-based therapies promote myocardial repair; however, the poor engraftment of the transferred stem cell populations within the infarcted myocardium is a major limitation, regardless of the cell type. One explanation for poor cell retention is attributed to the harsh inflammatory response mounted following MI. The inflammatory response coupled to cardiac repair processes is divided into two distinct phases. The first phase is initiated during ischemic injury when necrosed myocardium releases Danger Associated Molecular Patterns (DAMPs) and chemokines/cytokines to induce the activation and recruitment of neutrophils and pro-inflammatory M1 macrophages (MΦs); in turn, facilitating necrotic tissue clearance. During the second phase, a shift from the M1 inflammatory functional phenotype to the M2 anti-inflammatory and pro-reparative functional phenotype, permits the resolution of inflammation and the establishment of tissue repair. T-regulatory cells (Tregs) are also influential in mediating the establishment of the pro-reparative phase by directly regulating M1 to M2 MΦ differentiation. Current studies suggest CD4+ T-lymphocyte populations become activated when presented with autoantigens released from the injured myocardium. The identity of the cardiac autoantigens or paracrine signaling molecules released from the ischemic tissue that directly mediate the phenotypic plasticity of T-lymphocyte populations in the post-MI heart are just beginning to be elucidated. Stem cells are enriched centers that contain a diverse paracrine secretome that can directly regulate responses within neighboring cell populations. Previous studies identify that stem cell mediated paracrine signaling can influence the phenotype and function of immune cell populations in vitro, but how stem cells directly mediate the inflammatory microenvironment of the ischemic heart is poorly characterized and is a topic of extensive investigation. In this review, we summarize the complex literature that details the inflammatory microenvironment of the ischemic heart and provide novel insights regarding how paracrine mediated signaling produced by stem cell-based therapies can regulate immune cell subsets to facilitate pro-reparative myocardial wound healing.

Myocardial infarction triggers cardioprotective antigen-specific T helper cell responses

T cell autoreactivity is a hallmark of autoimmune diseases but can also benefit self-maintenance and foster tissue repair. Herein, we investigated whether heart-specific T cells exert salutary or detrimental effects in the context of myocardial infarction (MI), the leading cause of death worldwide. After screening more than 150 class-II-restricted epitopes, we found that myosin heavy chain alpha (MYHCA) was a dominant cardiac antigen triggering post-MI CD4+ T cell activation in mice. Transferred MYHCA614-629-specific CD4+ T (TCR-M) cells selectively accumulated in the myocardium and mediastinal lymph nodes (med-LN) of infarcted mice, acquired a Treg phenotype with a distinct pro-healing gene expression profile, and mediated cardioprotection. Myocardial Treg cells were also detected in autopsies from patients who suffered a MI. Noninvasive PET/CT imaging using a CXCR4 radioligand revealed enlarged med-LNs with increased cellularity in MI-patients. Notably, the med-LN alterations observed in MI patients correlated with the infarct size and cardiac function. Taken together, the results obtained in our study provide evidence showing that MI-context induces pro-healing T cell autoimmunity in mice and confirms the existence of an analogous heart/med-LN/T cell axis in MI patients.

miRNA-181a over-expression in mesenchymal stem cell-derived exosomes influenced inflammatory response after myocardial ischemia-reperfusion injury

AIMS

The inflammation modulation effects of mesenchymal stromal cell-derived exosomes (MSC-EXO) are well established. We aimed to explore the mechanism behind the inflammatory responses of numerous exosomal cargo molecules that have been neglected in molecular biology research, and to develop an exosomal cargo delivery system that can exert a stronger therapeutic effect on myocardial ischemia-reperfusion (I/R) injury.

MAIN METHODS

Computational approaches were used to identify key exosomal miRNAs and their downstream mRNAs that are expressed in the inflammatory response. Direct interactions between miRNA-181a and the c-Fos mRNA complex were confirmed by luciferase reporter assay. MSC-EXO carrying miRNA-181a-overexpressing lentiviruses were intramyocardially injected into a mouse model of myocardial I/R injury. I/R progression was evaluated through echocardiography and immunofluorescence microscopy.

KEY FINDINGS

miRNA-181a provided substantial coverage against a host of immune-related genes through the miRNA-mRNA network. miRNA-181a delivery by MSC-EXO combined the immune-suppressing effect of miRNA-181a and the cell targeting capability of MSC-EXO to exert a stronger therapeutic effect on myocardium I/R injury.

SIGNIFICANCE

We showed the potential of MSC-EXO as a tool for the specific delivery of small RNAs in vivo. This study shed new light on the potential application of miRNA-181a-overexpressing MSC-EXO as a therapeutic strategy for myocardial I/R injury.

Lymphocytic subsets play distinct roles in heart diseases

Heart diseases are one of the leading causes of death for humans in the world. Increasing evidence has shown that myocardial injury induced innate and adaptive immune responses upon early cellular damage but also during chronic phases post-injury. The immune cells can not only aggravate the injury but also play an essential role in the induction of wound healing responses, which means they play a complex role throughout the acute inflammatory response and reparative response after cardiac injury. This review will summarize the current experimental and clinical evidence of lymphocytes, one of the major types of immune cells, participate in heart diseases and try to explain the possible role of these immune cells following cardiac injury.

Novel Molecular Targets Participating in Myocardial Ischemia-Reperfusion Injury and Cardioprotection

Worldwide morbidity and mortality from acute myocardial infarction (AMI) and related heart failure remain high. While effective early reperfusion of the criminal coronary artery after a confirmed AMI is the typical treatment at present, collateral myocardial ischemia-reperfusion injury (MIRI) and pertinent cardioprotection are still challenging to address and have inadequately understood mechanisms. Therefore, unveiling the related novel molecular targets and networks participating in triggering and resisting the pathobiology of MIRI is a promising and valuable frontier. The present study specifically focuses on the recent MIRI advances that are supported by sophisticated bio-methodology in order to bring the poorly understood interrelationship among pro- and anti-MIRI participant molecules up to date, as well as to identify findings that may facilitate the further investigation of novel targets.

Galectin-1 as an Emerging Mediator of Cardiovascular Inflammation: Mechanisms and Therapeutic Opportunities

Galectin-1 (Gal-1), an evolutionarily conserved β-galactoside-binding lectin, controls immune cell homeostasis and tempers acute and chronic inflammation by blunting proinflammatory cytokine synthesis, engaging T-cell apoptotic programs, promoting expansion of T regulatory (Treg) cells, and deactivating antigen-presenting cells. In addition, this lectin promotes angiogenesis by co-opting the vascular endothelial growth factor receptor (VEGFR) 2 signaling pathway. Since a coordinated network of immunomodulatory and proangiogenic mediators controls cardiac homeostasis, this lectin has been proposed to play a key hierarchical role in cardiac pathophysiology via glycan-dependent regulation of inflammatory responses. Here, we discuss the emerging roles of Gal-1 in cardiovascular diseases including acute myocardial infarction, heart failure, Chagas cardiomyopathy, pulmonary hypertension, and ischemic stroke, highlighting underlying anti-inflammatory mechanisms and therapeutic opportunities. Whereas Gal-1 administration emerges as a potential novel treatment option in acute myocardial infarction and ischemic stroke, Gal-1 blockade may contribute to attenuate pulmonary arterial hypertension.

Inflammation following acute myocardial infarction: Multiple players, dynamic roles, and novel therapeutic opportunities

Acute myocardial infarction (AMI) and the heart failure that often follows, are major causes of death and disability worldwide. As such, new therapies are required to limit myocardial infarct (MI) size, prevent adverse left ventricular (LV) remodeling, and reduce the onset of heart failure following AMI. The inflammatory response to AMI, plays a critical role in determining MI size, and a persistent pro-inflammatory reaction can contribute to adverse post-MI LV remodeling, making inflammation an important therapeutic target for improving outcomes following AMI. In this article, we provide an overview of the multiple players (and their dynamic roles) involved in the complex inflammatory response to AMI and subsequent LV remodeling, and highlight future opportunities for targeting inflammation as a therapeutic strategy for limiting MI size, preventing adverse LV remodeling, and reducing heart failure in AMI patients.

Role of the immune system in cardiac tissue damage and repair following myocardial infarction

INTRODUCTION

The immune system plays a crucial role in the initiation, development, and resolution of inflammation following myocardial infarction (MI). The lack of oxygen and nutrients causes the death of cardiomyocytes and leads to the exposure of danger-associated molecular patterns that are recognized by the immune system to initiate inflammation.

RESULTS

At the initial stage of post-MI inflammation, the immune system further damages cardiac tissue to clear cell debris. The excessive production of reactive oxygen species (ROS) by immune cells and the inability of the anti-oxidant system to neutralize ROS cause oxidative stress that further aggravates inflammation. On the other hand, the cells of both innate and adaptive immune system and their secreted factors are critically instrumental in the very dynamic and complex processes of regulating inflammation and mediating cardiac repair.

CONCLUSIONS

It is important to decipher the balance between detrimental and beneficial effects of the immune system in MI. This enables us to identify better therapeutic targets for reducing the infarct size, sustaining the cardiac function, and minimizing the likelihood of heart failure. This review discusses the role of both innate and adaptive immune systems in cardiac tissue damage and repair in experimental models of MI.

Myocardial fibrosis seen through the lenses of T-cell biology

Lymphocytes came recently into focus as modulators of non-infectious myocardial diseases. Several lines of experimental evidence now indicate that CD4(+) T-cells can influence the healing and scarring processes that follow a myocardial infarction episode. Furthermore, such heart-directed T-cell activity has also been implicated in the pathogenesis cardiac remodeling that develops in response to chronic pressure-overload conditions. Mechanistically, different T-cell subsets can secrete several mediators and growth factors that influence the myocardial molecular milieu and directly interfere with the macrophages' and fibroblasts' activity. Therefore, the present review summarizes the current experimental evidence on the role of T-cells in myocardial scar formation after infarction and myocardial fibrosis as central mechanism of ventricular remodeling.