Regulatory T-Cell Response to Low-Dose Interleukin-2 in Ischemic Heart Disease.

Regulatory T-Cell Response to Low-Dose Interleukin-2 in Ischemic Heart Disease This phase 1b/2a, randomized, double-blind, placebo-controlled, dose-escalation trial tested low-dose subcutaneous aldesleukin (recombinant IL-2) in patients with ischemic heart disease. Low-dose IL-2 expanded Tregs, without adverse events of major concern. Single-cell RNA-sequencing of circulating immune cells was used to provide mechanistic assessment of the treatment's effects.

Soluble fibrinogen­like protein 2 levels are decreased in patients with ischemic heart failure and associated with cardiac function.

Soluble fibrinogen­like protein 2 (sFGL2), as a novel effector of regulatory T cells (Tregs), exhibits immune regulatory activity in several inflammatory diseases. Immune activation and persistent inflammation participate in the progression of ischemic heart failure (IHF). The present study aimed to determine serum sFGL2 levels in patients with IHF and explore the relationship between sFGL2 levels and cardiac function. A total of 104 patients with IHF and 32 healthy controls were enrolled. patients with IHF were further split into subgroups according to the New York Heart Association functional classification or left ventricular ejection fraction (LVEF). Serum sFGL2 levels and peripheral Tregs frequencies were analyzed by ELISA and flow cytometry, respectively. The suppressive function of Tregs was measured by proliferation and functional suppression assays. Serum levels of sFGL2 and circulating Tregs frequencies were significantly decreased in patients with IHF compared with healthy controls. In patients with IHF, sFGL2 levels and Tregs frequencies were decreased with the deterioration of cardiac function. Tregs from patients with IHF exhibited compromised ability to suppress CD4+CD25­ T cells proliferation and inflammatory cytokines secretion. Specifically, sFGL2 levels and Tregs frequencies positively correlated with LVEF, whereas negatively correlated with left ventricular end­diastolic dimension and N­terminal pro­brain natriuretic peptide. sFGL2 levels were positively correlated with Tregs frequencies. In conclusion, the reduction of serum sFGL2 levels are associated with the progression of IHF and sFGL2 could be used as a potential indicator for predicting disease severity.

Cardiac Dysfunction in Rheumatoid Arthritis: The Role of Inflammation.

Rheumatoid arthritis is a chronic, systemic inflammatory disease that carries an increased risk of mortality due to cardiovascular disease. The link between inflammation and atherosclerotic disease is clear; however, recent evidence suggests that inflammation may also play a role in the development of nonischemic heart disease in rheumatoid arthritis (RA) patients. We consider here the link between inflammation and cardiovascular disease in the RA community with a focus on heart failure with preserved ejection fraction. The effect of current anti-inflammatory therapeutics, used to treat RA patients, on cardiovascular disease are discussed as well as whether targeting resolution of inflammation might offer an alternative strategy for tempering inflammation and subsequent inflammation-driven comorbidities in RA.

The evolving cardiac lymphatic vasculature in development, repair and regeneration.

The lymphatic vasculature has an essential role in maintaining normal fluid balance in tissues and modulating the inflammatory response to injury or pathogens. Disruption of normal development or function of lymphatic vessels can have severe consequences. In the heart, reduced lymphatic function can lead to myocardial oedema and persistent inflammation. Macrophages, which are phagocytic cells of the innate immune system, contribute to cardiac development and to fibrotic repair and regeneration of cardiac tissue after myocardial infarction. In this Review, we discuss the cardiac lymphatic vasculature with a focus on developments over the past 5 years arising from the study of mammalian and zebrafish model organisms. In addition, we examine the interplay between the cardiac lymphatics and macrophages during fibrotic repair and regeneration after myocardial infarction. Finally, we discuss the therapeutic potential of targeting the cardiac lymphatic network to regulate immune cell content and alleviate inflammation in patients with ischaemic heart disease.

Immature Platelets and Risk of Cardiovascular Events among Patients with Ischemic Heart Disease: A Systematic Review.

BACKGROUND: Immature platelets are larger and may be more thrombogenic than mature platelets. This systematic review included studies on the association between mean platelet volume (MPV), immature platelet count (IPC), and immature platelet fraction (IPF) and the risk of major cardiovascular events (MACEs) in patients with acute coronary syndrome (ACS) or stable coronary artery disease (CAD). METHODS: The literature search included studies in PubMed, Embase, Web of Science, and Cochrane Library. The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Effect estimates that included multivariate adjusted odds ratios, relative risks, or hazard ratios were extracted. RESULTS: Forty-two studies were identified. High MPV was positively associated with MACE in 20 of 26 studies of patients with ACS, four of five studies in patients with stable CAD, and in all six studies comprising a combined population with ACS and stable CAD. Using continuous models of MPV in patients with ACS, effect estimates varied from 0.90 (95% confidence interval [CI]: 0.95-1.03) to 1.66 (95% CI: 1.32-2.09). The strength of these associations was broadly similar among patients with stable CAD and in combined populations. Five studies investigated IPC or IPF as exposures and all reported positive associations with MACE among patients with ACS, stable CAD, or in combined populations. CONCLUSION: This review demonstrated clear evidence for positive associations between measures of immature platelets and subsequent risk of MACE in acute and stable ischemic heart disease patients.

Expression of Paracrine Effectors in Human Adipose-Derived Mesenchymal Stem Cells Treated With Plasma From Brown Bears (Ursus arctos).

Adipose-derived mesenchymal stem cells (ADSCs) are promising candidates for novel cell therapeutic applications. Hibernating brown bears sustain tissue integrity and function via unknown mechanisms, which might be plasma borne. We hypothesized that plasma from hibernating bears may increase the expression of favorable factors from human ADSCs. In an experimental study, ADSCs from patients with ischemic heart disease were treated with interventional media containing plasma from hibernating and active bears, respectively, and with control medium. Extracted RNA from the ADSCs was sequenced using next generation sequencing. Statistical analyses of differentially expressed genes were performed using fold change analysis, pathway analysis, and gene ontology. As a result, we found that genes associated with inflammation, such as IGF1, PGF, IL11, and TGFA, were downregulated by > 10-fold in ADSCs treated with winter plasma compared with control. Genes important for cardiovascular development, ADM, ANGPTL4, and APOL3, were upregulated in ADSCs when treated with winter plasma compared with summer plasma. ADSCs treated with bear plasma, regardless if it was from hibernating or active bears, showed downregulation of IGF1, PGF, IL11, INHBA, IER3, and HMOX1 compared with control, suggesting reduced cell growth and differentiation. This can be summarized in the conclusion that plasma from hibernating bears suppresses inflammatory genes and activates genes associated with cardiovascular development in human ADSCs. Identifying the involved regulator(s) holds therapeutic potential.

Lipid Mediators in Critically Ill Patients: A Step Towards Precision Medicine.

A dysregulated response to systemic inflammation is a common pathophysiological feature of most conditions encountered in the intensive care unit (ICU). Recent evidence indicates that a dysregulated inflammatory response is involved in the pathogenesis of various ICU-related disorders associated with high mortality, including sepsis, acute respiratory distress syndrome, cerebral and myocardial ischemia, and acute kidney injury. Moreover, persistent or non-resolving inflammation may lead to the syndrome of persistent critical illness, characterized by acquired immunosuppression, catabolism and poor long-term functional outcomes. Despite decades of research, management of many disorders in the ICU is mostly supportive, and current therapeutic strategies often do not take into account the heterogeneity of the patient population, underlying chronic conditions, nor the individual state of the immune response. Fatty acid-derived lipid mediators are recognized as key players in the generation and resolution of inflammation, and their signature provides specific information on patients' inflammatory status and immune response. Lipidomics is increasingly recognized as a powerful tool to assess lipid metabolism and the interaction between metabolic changes and the immune system via profiling lipid mediators in clinical studies. Within the concept of precision medicine, understanding and characterizing the individual immune response may allow for better stratification of critically ill patients as well as identification of diagnostic and prognostic biomarkers. In this review, we provide an overview of the role of fatty acid-derived lipid mediators as endogenous regulators of the inflammatory, anti-inflammatory and pro-resolving response and future directions for use of clinical lipidomics to identify lipid mediators as diagnostic and prognostic markers in critical illness.

Potential Therapeutic Role of Purinergic Receptors in Cardiovascular Disease Mediated by SARS-CoV-2.

Novel coronavirus disease 2019 (COVID-19) causes pulmonary and cardiovascular disorders and has become a worldwide emergency. Myocardial injury can be caused by direct or indirect damage, particularly mediated by a cytokine storm, a disordered immune response that can cause myocarditis, abnormal coagulation, arrhythmia, acute coronary syndrome, and myocardial infarction. The present review focuses on the mechanisms of this viral infection, cardiac biomarkers, consequences, and the possible therapeutic role of purinergic and adenosinergic signalling systems. In particular, we focus on the interaction of the extracellular nucleotide adenosine triphosphate (ATP) with its receptors P2X1, P2X4, P2X7, P2Y1, and P2Y2 and of adenosine (Ado) with A2A and A3 receptors, as well as their roles in host immune responses. We suggest that receptors of purinergic signalling could be ideal candidates for pharmacological targeting to protect against myocardial injury caused by a cytokine storm in COVID-19, in order to reduce systemic inflammatory damage to cells and tissues, preventing the progression of the disease by modulating the immune response and improving patient quality of life.

Regulatory T cells in ischemic cardiovascular injury and repair.

Ischemic injury triggers a heightened inflammatory response that is essential for tissue repair, but excessive and chronic inflammatory responses contribute to the pathogenesis of ischemic cardiovascular disease. Regulatory T cells (Tregs), a major regulator of self-tolerance and immune suppression, control innate and adaptive immune responses, modulate specific immune cell subsets, prevent excessive inflammation, and participate in tissue repair after ischemia. Herein, we summarize the multiple potential mechanisms by which Tregs exert suppressor functions including modulation of cytokine production, alteration of cell-cell interactions, and disruption of metabolic pathways. Furthermore, we review the role of Tregs implicated in ischemic injury and repair including myocardial, limb, and cerebral ischemia. We conclude with a perspective on the therapeutic opportunities and future challenges of Treg biology in understanding the pathogenesis of ischemic cardiovascular disease states.

Artemisinin suppresses myocardial ischemia-reperfusion injury via NLRP3 inflammasome mechanism.

Artemisinin is known for its pharmaceutical effect against malaria and received increased attention for its other potential function. Mounting evidence suggest that artemisinin could also exert cardioprotective effects while the understanding of its regulatory mechanism is still limited. This study is designed to investigate the role of artemisinin in myocardial ischemia/reperfusion (I/R) injury and the involvement of NLRP3 inflammasome. Artemisinin was administrated for 14 consecutive days intragastrically before I/R injury. Cardiac function was assessed by echocardiography. Infarct area was observed through HE and TTC staining. Apoptosis and autophagy were assessed by TUNEL and Western blotting. The artemisinin-treated myocardial I/R rats demonstrated less severe myocardial I/R injury (smaller infarct size and lower CK-MB, LDH), significant inhibition of cardiac autophagy (decreased LC3II/I and increased p62), improved mitochondrial electron transport chain activity, concomitant with decreased activation of NLRP3 inflammasome (decreased NLRP3, ASC, cleaved caspase-1, IL-1ß). In conclusion, our findings further confirmed that activation of the NLRP3 inflammasome pathway is involved in myocardial I/R injury, whereas artemisinin preconditioning could effectively protect against myocardial I/R injury through suppression of NLRP3 inflammasome activation. Therefore, the NLRP3 inflammasome might serve as a promising therapeutic target providing new mechanisms for understanding the effect of artemisinin during the evolution of myocardial infarction.

[Effects of electroacupuncture pretreatment on cardiac function and immune inflammatory response in mice with acute myocardial ischemia].

OBJECTIVE: To observe the effects of electroacupuncture (EA) pretreatment on the cardiac ejection fraction (EF), the number of macrophages in spleen and heart, and the expression of nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) and interleukin-1ß (IL-1ß) in myocardium in mice with acute myocardial ischemia, and to explore the possible mechanism of EA pretreatment on promoting myocardial protection. METHODS: A total of 30 male C57BL/6J mice were randomly divided into a control group, a model group and an EA pretreatment group, 10 rats in each group. The acute myocardial ischemia model was established by ligating the left anterior descending branch of the coronary artery in the model group and EA pretreatment group, while threading but no ligating at left anterior descending branch of the coronary artery was applied in the control group. In the EA pretreatment group, mice were intervented with EA at bilateral "Neiguan" (PC 6), disperse-dense wave, frequency of 2 Hz/15 Hz, intensity of 2 mA; each EA treatment last for 20 min, once a day, and 3-day treatment was given before model establishment. The EF value was evaluated by ultrasonic cardiogram; the number of macrophages in spleen and heart was measured by flow cytometry; the expression level of NLRP3 and IL-1ß in myocardium was measured by Western blot. RESULTS: Compared with the control group, the EF value was decreased in the model group (P<0.001), the number of macrophages in the heart and spleen was increased (P<0.001), and the expression level of NLRP3 and IL-1ß in the myocardium was increased (P<0.001, P<0.01). Compared with the model group, the EF value was increased in the EA pretreatment group (P<0.01), the number of macrophages in the heart and spleen was decreased (P<0.01), and the expression level of NLRP3 and IL-1ß in the myocardium was decreased (P<0.01, P<0.05). CONCLUSION: EA pretreatment could reduce the number of macrophages in spleen and heart, down-regulate the expression of NLRP3 and IL-1ß in myocardial tissue in mice with acute myocardial ischemia, which could relieve the local inflammatory response and achieve the myocardial protective effect.

Cleavage of cyclic AMP-responsive element-binding protein H aggravates myocardial hypoxia reperfusion injury in a hepatocyte-myocardial cell co-culture system.

OBJECTIVE: This study aimed to determine whether proinflammatory cytokines have an effect on myocardial cells (MCs) and hepatocytes during myocardial ischemia to induce cyclic AMP-responsive element-binding protein H (CREBH) cleavage, activate the acute phase response in the liver, and cause a superimposed injury in MCs. METHODS: In this study, a hepatocyte-MC transwell co-culture system was used to investigate the relationship between myocardial hypoxia/reperfusion injury and CREBH cleavage. MCs and hepatocytes of neonatal rats were obtained from the ventricles and livers of Sprague-Dawley rats, respectively. MCs were inoculated into the lower chamber of transwell chambers for 12 hours under hypoxia. Levels of the endoplasmic reticulum stress protein glucose-regulated protein 78 in MCs, CREBH in hepatocytes, inflammatory factor (tumor necrosis factor-α and interleukin-6) levels, and cell viability were evaluated. The effect of CREBH knockdown was also studied using a CREBH-specific short hairpin RNA (Ad-CREBHi). RESULTS: We found that proinflammatory cytokines affect MCs and hepatocytes during myocardial ischemia to induce CREBH cleavage, activate the acute phase response in the liver, and cause superimposed injury in MCs. CONCLUSIONS: Expression of CREBH aggravates myocardial injury during myocardial ischemia.

The Prognostic Impact of Circulating Regulatory T Lymphocytes on Mortality in Patients with Ischemic Heart Failure with Reduced Ejection Fraction.

BACKGROUND: Heart failure with reduced ejection fraction (HFrEF) constitutes a global health issue. While proinflammatory cytokines proved to have a pivotal role in the development and progression of HFrEF, less attention has been paid to the cellular immunity. Regulatory T lymphocytes (Tregs) seem to have an important role in the induction and maintenance of immune homeostasis. Therefore, we aimed to investigate the impact of Tregs on the outcome in HFrEF. METHODS: We prospectively enrolled 112 patients with HFrEF and performed flow cytometry for cell phenotyping. Individuals were stratified in ischemic (iHFrEF, n = 57) and nonischemic etiology (niHFrEF, n = 57) and nonischemic etiology (niHFrEF. RESULTS: Comparing patients with iHFrEF to niHFrEF, we found a significantly lower fraction of Tregs within lymphocytes in the ischemic subgroup (0.42% vs. 0.56%; p = 0.009). After a mean follow-up time of 4.5 years, 32 (28.6%) patients died due to cardiovascular causes. We found that Tregs were significantly associated with cardiovascular survival in the entire study cohort with an adjusted HR per one standard deviation (1-SD) of 0.60 (95% CI: 0.39-0.92; p = 0.009). After a mean follow-up time of 4.5 years, 32 (28.6%) patients died due to cardiovascular causes. We found that Tregs were significantly associated with cardiovascular survival in the entire study cohort with an adjusted HR per one standard deviation (1-SD) of 0.60 (95% CI: 0.39-0.92; p = 0.009). After a mean follow-up time of 4.5 years, 32 (28.6%) patients died due to cardiovascular causes. We found that Tregs were significantly associated with cardiovascular survival in the entire study cohort with an adjusted HR per one standard deviation (1-SD) of 0.60 (95% CI: 0.39-0.92; p = 0.009). After a mean follow-up time of 4.5 years, 32 (28.6%) patients died due to cardiovascular causes. We found that Tregs were significantly associated with cardiovascular survival in the entire study cohort with an adjusted HR per one standard deviation (1-SD) of 0.60 (95% CI: 0.39-0.92. CONCLUSION: Our results indicate a potential influence of Tregs in the pathogenesis and progression of iHFrEF, fostering the implication of cellular immunity in iHFrEF pathophysiology and proving Tregs as a predictor for long-term survival among iHFrEF patients. A preview of this study has been presented at a meeting of the European Society of Cardiology earlier this year.

Electroacupuncture preconditioning attenuates acute myocardial ischemia injury through inhibiting NLRP3 inflammasome activation in mice.

AIMS: Electro-acupuncture pretreatment (EAP) plays a protective role in myocardial ischemia (MI) injury. However, the underlying mechanism remains unclear. A growing body of evidence suggests postinfarction inflammatory response directly affects the remodeling of ventricular function. The purpose of this study was to investigate whether EAP alleviates MI through NLRP3 inflammasome inhibition. MATERIALS AND METHODS: We constructed an AMI model by ligating the left anterior descending (LAD) coronary artery after 3 days of EAP with C57BL/6 mice. Echocardiography and TTC staining were employed to evaluate cardiac function and infarct size after 24 h of ischemia. HE staining and immunohistochemistry were employed to determine inflammatory level. Then, inflammasome activation was detected by western blotting, and macrophage polarization and neutrophil infiltration were observed by flow cytometry. KEY FINDINGS: Our preliminary findings showed that EAP reduced the infarct area and increased fractional shortening (FS) and ejection fraction (EF) and decreased the degree of inflammation after AMI injury. Meanwhile, EAP inhibited the expression of NLRP3, cleaved caspase-1 and IL-1ß in ischemia myocardial tissue, companied by inhibiting the expression of F4/80+, CD11b+, CD206low macrophages and activated M2 macrophage, and decreasing Ly-6G+CD11b+ neutrophils in ischemia myocardial and spleen tissue. SIGNIFICANCE: EAP inhibits the activation of NLRP3 inflammasome, promotes M2 polarization of macrophages and reduces the recruitment of neutrophils in damaged myocardium, thereby decreases the infarct size and improves the cardiac function.

Role of neutrophils in ischemic heart failure.

Amplified innate leukocytes (neutrophils and monocytes/macrophages) are associated with advanced ischemic and non-ischemic heart failure (HF). Intensified neutrophilic leukocytosis (neutrophilia) and sustained activation of neutrophils is the predominant factor that determines over activated inflammation in acute HF and the outcome of long-term chronic HF. After heart attack, the first wave of innate responsive and short-lived neutrophils is essential for the initiation of inflammation, resolution of inflammation, and cardiac repair, however uncontrolled and long-term activation of neutrophils leads to collateral damage of myocardium. In the presented review, we highlighted the interactive and integrative role of neutrophil phenotypes in cellular and molecular events of ischemic HF. In addition, we discussed the current, nonimmune, immune, and novel paradigms of neutrophils in HF associated with differential factors with a specific interest in non-resolving inflammation and resolution physiology.

Sal B Alleviates Myocardial Ischemic Injury by Inhibiting TLR4 and the Priming Phase of NLRP3 Inflammasome.

Salvianolic acid B is one of the main water-soluble components of Salvia miltiorrhiza Bge. Many reports have shown that it has significant anti-myocardial ischemia effect. However, the underlying mechanism remains unclear. Our present study demonstrated that Sal B could alleviate myocardial ischemic injury by inhibiting the priming phase of NLRP3 inflammasome. In vivo, serum c-troponin I (cTn), lactate dehydrogenase (LDH) levels, the cardiac function and infract size were examined. We found that Sal B could notably reduce the myocardial ischemic injury caused by ligation of the left anterior descending coronary artery. In vitro, Sal B down-regulated the TLR4/NF-κB signaling cascades in lipopolysaccharide (LPS)-stimulated H9C2 cells. Furthermore, Sal B reduced the expression levels of IL-1ß and NLRP3 inflammasome in a dose-dependent manner. In short, our study provided evidence that Sal B could attenuate myocardial ischemic injury via inhibition of TLR4/NF-κB/NLRP3 signaling pathway. And in an upstream level, MD-2 may be the potential target.

Podoplanin neutralization improves cardiac remodeling and function after acute myocardial infarction.

Podoplanin, a small mucine-type transmembrane glycoprotein, has been recently shown to be expressed by lymphangiogenic, fibrogenic and mesenchymal progenitor cells in the acutely and chronically infarcted myocardium. Podoplanin binds to CLEC-2, a C-type lectin-like receptor 2 highly expressed by CD11bhigh cells following inflammatory stimuli. Why podoplanin expression appears only after organ injury is currently unknown. Here, we characterize the role of podoplanin in different stages of myocardial repair after infarction and propose a podoplanin-mediated mechanism in the resolution of post-MI inflammatory response and cardiac repair. Neutralization of podoplanin led to significant improvements in the left ventricular functions and scar composition in animals treated with podoplanin neutralizing antibody. The inhibition of the interaction between podoplanin and CLEC-2 expressing immune cells in the heart enhances the cardiac performance, regeneration and angiogenesis post MI. Our data indicates that modulating the interaction between podoplanin positive cells with the immune cells after myocardial infarction positively affects immune cell recruitment and may represent a novel therapeutic target to augment post-MI cardiac repair, regeneration and function.

Notch Signaling Regulates Immune Responses in Atherosclerosis.

Atherosclerosis is a chronic autoimmune inflammatory disease that can cause coronary artery disease, stroke, peripheral artery disease, depending on which arteries are affected. At the beginning of atherosclerosis plasma lipoproteins accumulate in the sub-endothelial space. In response, monocytes migrate from the circulation through the endothelium into the intima where they differentiate into macrophages. These early events trigger a complex immune response that eventually involves many cellular subtypes of both innate and adaptive immunity. The Notch signaling pathway is an evolutionary conserved cell signaling system that mediates cell-to-cell communication. Recent studies have revealed that Notch modulate atherosclerosis by controlling macrophages polarization into M1 or M2 subtypes. Furthermore, it is known that Notch signaling controls differentiation and activity of T-helper and cytotoxic T-cells in inflammatory diseases. In this review, we will discuss the role of Notch in modulating immunity in the context of atherosclerosis and whether targeting Notch may represent a therapeutic strategy.