Antibody against interleukin-6 receptor attenuates left ventricular remodelling after myocardial infarction in mice

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.

Causal relationship between inflammatory markers and left ventricle geometry and function: A 2-sample Mendelian randomization study

Studies have shown that some inflammatory markers can predict the risk of cardiovascular disease (CVD) and affect the structure and function of the heart. However, a causal relationship between inflammatory markers and the cardiac structure and function has not yet been established. Thus, we conducted a 2-sample Mendelian randomization (MR) study to explore the potential causal relationship between inflammatory markers and prognostically-related left ventricular (LV) parameters. Instrumental variables (IVs) for C-reactive protein (CRP), interleukin-6 (IL-6), and myeloperoxidase (MPO) levels were selected from the databases of large genome-wide association studies (GWAS). Summary statistics for LV parameters, including LV mass, ejection fraction, end-diastolic and systolic volumes, and the ratio of LV mass to end-diastolic volume, were obtained from cardiovascular magnetic resonance studies of the UK Biobank (n = 16923). The inverse-variance weighted (IVW) method was the primary analytical method used, and was complemented with the MR-Egger, weighted median, simple mode, weighted mode, and MR pleiotropy residual sum and outlier (MR-PRESSO) methods. Sensitivity analysis was performed to evaluate the robustness of the results. CRP was significantly associated with the LV mass in the IVW method (β = -0.13 g [95% confidence interval [CI], 0.78 g-1.00 g], P = .046). A higher standard deviation of genetically-predicted CRP levels was associated with a 0.13 ± 0.06 g lower LV mass. No causal relationships of IL-6 and MPO with LV parameters were found. No evidence of heterogeneity and pleiotropy was detected. Sensitivity analyses confirmed the robustness of the results. Two-sample MR analysis revealed a causal association between increased CRP level and decreased LV mass, whereas IL-6 and MPO levels did not influence the LV parameters. However, further research is required to validate our findings.

Hypoxic-Normoxic Crosstalk Activates Pro-Inflammatory Signaling in Human Cardiac Fibroblasts and Myocytes in a Post-Infarct Myocardium on a Chip

Myocardial infarctions locally deprive myocardium of oxygenated blood and cause immediate cardiac myocyte necrosis. Irreparable myocardium is then replaced with a scar through a dynamic repair process that is an interplay between hypoxic cells of the infarct zone and normoxic cells of adjacent healthy myocardium. In many cases, unresolved inflammation or fibrosis occurs for reasons that are incompletely understood, increasing the risk of heart failure. Crosstalk between hypoxic and normoxic cardiac cells is hypothesized to regulate mechanisms of repair after a myocardial infarction. To test this hypothesis, microfluidic devices are fabricated on 3D printed templates for co-culturing hypoxic and normoxic cardiac cells. This system demonstrates that hypoxia drives human cardiac fibroblasts toward glycolysis and a pro-fibrotic phenotype, similar to the anti-inflammatory phase of wound healing. Co-culture with normoxic fibroblasts uniquely upregulates pro-inflammatory signaling in hypoxic fibroblasts, including increased secretion of tumor necrosis factor alpha (TNF-α). In co-culture with hypoxic fibroblasts, normoxic human induced pluripotent stem cell (hiPSC)-derived cardiac myocytes also increase pro-inflammatory signaling, including upregulation of interleukin 6 (IL-6) family signaling pathway and increased expression of IL-6 receptor. Together, these data suggest that crosstalk between hypoxic fibroblasts and normoxic cardiac cells uniquely activates phenotypes that resemble the initial pro-inflammatory phase of post-infarct wound healing.

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 in cardiovascular diseases: molecular mechanisms and therapeutic targets

The immune response holds a pivotal role in cardiovascular disease development. As multifunctional cells of the innate immune system, macrophages play an essential role in initial inflammatory response that occurs following cardiovascular injury, thereby inducing subsequent damage while also facilitating recovery. Meanwhile, the diverse phenotypes and phenotypic alterations of macrophages strongly associate with distinct types and severity of cardiovascular diseases, including coronary heart disease, valvular disease, myocarditis, cardiomyopathy, heart failure, atherosclerosis and aneurysm, which underscores the importance of investigating macrophage regulatory mechanisms within the context of specific diseases. Besides, recent strides in single-cell sequencing technologies have revealed macrophage heterogeneity, cell-cell interactions, and downstream mechanisms of therapeutic targets at a higher resolution, which brings new perspectives into macrophage-mediated mechanisms and potential therapeutic targets in cardiovascular diseases. Remarkably, myocardial fibrosis, a prevalent characteristic in most cardiac diseases, remains a formidable clinical challenge, necessitating a profound investigation into the impact of macrophages on myocardial fibrosis within the context of cardiac diseases. In this review, we systematically summarize the diverse phenotypic and functional plasticity of macrophages in regulatory mechanisms of cardiovascular diseases and unprecedented insights introduced by single-cell sequencing technologies, with a focus on different causes and characteristics of diseases, especially the relationship between inflammation and fibrosis in cardiac diseases (myocardial infarction, pressure overload, myocarditis, dilated cardiomyopathy, diabetic cardiomyopathy and cardiac aging) and the relationship between inflammation and vascular injury in vascular diseases (atherosclerosis and aneurysm). Finally, we also highlight the preclinical/clinical macrophage targeting strategies and translational implications.

Inflammation as the nexus: exploring the link between acute myocardial infarction and chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), particularly following acute exacerbations (AE-COPD), significantly heightens the risks and mortality associated with acute myocardial infarction (AMI). The intersection of COPD and AMI is characterised by a considerable overlap in inflammatory mechanisms, which play a crucial role in the development of both conditions. Although extensive research has been conducted on individual inflammatory pathways in AMI and COPD, the understanding of thrombo-inflammatory crosstalk in comorbid settings remains limited. The effectiveness of various inflammatory components in reducing AMI infarct size or slowing COPD progression has shown promise, yet their efficacy in the context of comorbidity with COPD and AMI is not established. This review focuses on the critical importance of both local and systemic inflammation, highlighting it as a key pathophysiological connection between AMI and COPD/AE-COPD.

Japanese Traditional Herbal Medicine, Rikkunshito, Partially Suppresses Inflammatory Responses in Myocardial Ischemia/Reperfusion Injury

INTRODUCTION

Myocardial ischemia/reperfusion (I/R) injury can cause additional damage to an ischemic myocardium, even after successful reperfusion therapy. Inflammation is a mechanism that exacerbates myocardial damage after I/R injury. Rikkunshito (RKT) is a traditional Japanese herbal medicine widely used to treat gastrointestinal symptoms. It attenuates inflammation and fibrosis in some diseases of the heart; however, it remains unclear whether RKT exerts cardioprotective effects against myocardial I/R injury. To elucidate this, we evaluated the effects of RKT pre-treatment by oral administration on the myocardium in a mouse model of in vivo I/R injury.

METHODS

Mice were randomly assigned to a group receiving distilled water (DW) or one receiving RKT (1000 mg/kg/day) for 14 days orally. For each of the RKT and DW groups, a sham group, an I/R 2 h group, and an I/R 24 h group were created. On day 15, myocardial I/R surgery was performed. The left anterior descending coronary artery (LAD) was ligated for 30 min, and reperfusion time was set at 2 h or 24 h. The myocardial infarct size (IS) was measured after 2 h of reperfusion, and cardiac cytokine mRNA expression levels were evaluated by quantitative reverse transcription polymerase chain reaction (RT-PCR) after 2 h and 24 h of reperfusion.

RESULTS

RKT pre-treatment significantly suppressed the cardiac mRNA expression level of interleukin-1β in the RKT-I/R 2 h group compared to the DW-I/R 2 h group (P < 0.05). Additionally, RKT significantly suppressed the mRNA expression levels of transforming growth factor-β compared to DW; the same result was obtained for the expression levels of interleukin-6. However, RKT did not reduce the IS or mRNA expression levels of the cardiac congestive markers natriuretic peptide a (NPPA) and natriuretic peptide b (NPPB). In addition, RKT did not alter the plasma concentration of ghrelin and sirtuin 1 (Sirt1), which have been reported to be stimulated by RKT.

CONCLUSION

This study showed that pre-treatment of RKT for myocardial I/R injury partially suppressed inflammation-related cytokines. However, further studies are needed on the effect of RKT on the reduction of myocardial infarction size.

Targeting Key Inflammatory Mechanisms Underlying Heart Failure: A Comprehensive Review

Inflammation is a major component of heart failure (HF), causing peripheral vasculopathy and cardiac remodeling. High levels of circulating inflammatory cytokines in HF patients have been well recognized. The hallmark of the inflammatory imbalance is the insufficient production of anti-inflammatory mediators, a condition that leads to dysregulated cytokine activity. The condition progresses because of the pathogenic consequences of the cytokine imbalance, including the impact of endothelial dysfunction and adrenergic responsiveness deterioration, and unfavorable inotropic effects on the myocardium. Hence, to develop possible anti-inflammatory treatment options that will enhance the outcomes of HF patients, it is essential to identify the potential pathophysiological mechanisms of inflammation in HF. Inflammatory mediators, such as cytokines, adhesion molecules, and acute-phase proteins, are elevated during this process, highlighting the complex association between inflammation and HF. Therefore, these inflammatory markers can be used in predicting prognosis of the syndrome. Various immune cells impact on myocardial remodeling and recovery. They lead to stimulation, release of alarmins and risk-related molecule patterns. Targeting key inflammatory mechanisms seems a quite promising therapy strategy in HF. Cytokine modulation is only one of several possible targets in the fight against inflammation, as the potential molecular targets for therapy in HF include immune activation, inflammation, oxidative stress, alterations in mitochondrial bioenergetics, and autophagy.

Immune-related biomarkers in myocardial infarction; diagnostic/prognostic value and therapeutic potential

The incidence of myocardial infarction (MI) is increasing worldwide on an annual basis. The incorporation of circulating biomarkers, along with electrocardiography, echocardiography, coronary angiograms, and other diagnostic techniques, is essential in the evaluation, prediction, and therapeutic efficacy assessment of patients afflicted with MI. Biomarker evaluation has been employed in the diagnosis of MI for over five decades. Further biomarker research can be carried out as newer biomarkers have been discovered in pathways such as inflammatory response, neurohormonal stimulation, or myocardial stress that initiate significantly earlier than myocyte necrosis and the diagnostic establishment of cardiac troponins. The assessment of biomarkers for MI is on the brink of a significant transformation due to advancements in comprehending the intricate pathophysiology of the condition. This has led to a pursuit of innovative biomarkers that could potentially overcome the limitations of current biomarkers. For individuals with a high-risk profile, this may facilitate tailoring of appropriate treatment. This review places emphasis on a diverse array of biomarkers that have the potential to offer diagnostic and prognostic information, as well as the latest clinical and preclinical evidence that is driving theoretical advancements in cardiovascular immunotherapy.

Imaging Inflammation Past, Present, and Future: Focus on Cardioimmunology

Growing evidence implicates the immune system as a critical mediator of cardiovascular disease progression and a viable therapeutic target. Increased inflammatory cell activity is seen in the full spectrum of disorders from early-stage atherosclerosis through myocardial infarction, cardiomyopathy, and chronic heart failure. Although therapeutic strategies to modulate inflammation have shown promise in preclinical animal models, efficacy in patients has been modest owing in part to the variable severity of inflammation across individuals. The diverse leukocyte subpopulations involved in different aspects of heart disease pose a challenge to effective therapy, wherein adverse and beneficial aspects of inflammation require appropriate balance. Noninvasive molecular imaging enables tissue-level interrogation of inflammatory cells in the heart and vasculature to provide mechanistic and temporal insights into disease progression. Although clinical imaging has relied on 18F-FDG as a nonselective and crude marker of inflammatory cell activity, new imaging probes targeting cell surface markers of different leukocyte subpopulations present the opportunity to visualize and quantify distinct phases of cardiac and vessel wall inflammation. Similarly, therapies are evolving to more effectively isolate adverse from beneficial cell populations. This parallel development of immunocardiology and molecular imaging provides the opportunity to refine treatments using imaging guidance, building toward mechanism-based precision medicine. Here, we discuss progress in molecular imaging of immune cells in cardiology from use of 18F-FDG in the past to the present expansion of the radiotracer arsenal and then to a future theranostic paradigm of tracer-therapy compound pairs with shared targets. We then highlight the critical experiments required to advance the field from preclinical concept to clinical reality.

Targeting neuro-immune systems to achieve cardiac tissue repair following myocardial infarction: A review of therapeutic approaches from in-vivo preclinical to clinical studies

Myocardial healing following myocardial infarction (MI) toward either functional tissue repair or excessive scarring/heart failure, may depend on a complex interplay between nervous and immune system responses, myocardial ischemia/reperfusion injury factors, as well as genetic and epidemiological factors. Hence, enhancing cardiac repair post MI may require a more patient-specific approach targeting this complex interplay and not just the heart, bearing in mind that the dysregulation or modulation of just one of these systems or some of their mechanisms may determine the outcome either toward functional repair or toward heart failure. In this review we have elected to focus on existing preclinical and clinical in-vivo studies aimed at testing novel therapeutic approaches targeting the nervous and immune systems to trigger myocardial healing toward functional tissue repair. To this end, we have only selected clinical and preclinical in-vivo studies reporting on novel treatments targeting neuro-immune systems to ultimately treat MI. Next, we have grouped and reported treatments under each neuro-immune system. Finally, for each treatment we have assessed and reported the results of each clinical/preclinical study and then discussed their results collectively. This structured approach has been followed for each treatment discussed. To keep this review focused, we have deliberately omitted to cover other important and related research areas such as myocardial ischemia/reperfusion injury, cell and gene therapies as well as any ex-vivo and in-vitro studies. The review indicates that some of the treatments targeting the neuro-immune/inflammatory systems appear to induce beneficial effects remotely on the healing heart post MI, warranting further validation. These remote effects on the heart also indicates the presence of an overarching synergic response occurring across the nervous and immune systems in response to acute MI, which appear to influence cardiac tissue repair in different ways depending on age and timing of treatment delivery following MI. The cumulative evidence arising from this review allows also to make informed considerations on safe as opposed to detrimental treatments, and within the safe treatments to ascertain those associated with conflicting or supporting preclinical data, and those warranting further validation.

Pathophysiological Effects of Various Interleukins on Primary Cell Types in Common Heart Disease

Myocardial infarction (MI), heart failure, cardiomyopathy, myocarditis, and myocardial ischemia-reperfusion injury (I/R) are the most common heart diseases, yet there is currently no effective therapy due to their complex pathogenesis. Cardiomyocytes (CMs), fibroblasts (FBs), endothelial cells (ECs), and immune cells are the primary cell types involved in heart disorders, and, thus, targeting a specific cell type for the treatment of heart disease may be more effective. The same interleukin may have various effects on different kinds of cell types in heart disease, yet the exact role of interleukins and their pathophysiological pathways on primary cell types remain largely unexplored. This review will focus on the pathophysiological effects of various interleukins including the IL-1 family (IL-1, IL-18, IL-33, IL-37), IL-2, IL-4, the IL-6 family (IL-6 and IL-11), IL-8, IL-10, IL-17 on primary cell types in common heart disease, which may contribute to the more precise and effective treatment of heart disease.

Quo Vadis? Immunodynamics of Myeloid Cells after Myocardial Infarction

Myocardial infarction (MI), a major contributor to worldwide morbidity and mortality, is caused by a lack of blood flow to the heart. Affected heart tissue becomes ischemic due to deficiency of blood perfusion and oxygen delivery. In case sufficient blood flow cannot be timely restored, cardiac injury with necrosis occurs. The ischemic/necrotic area induces a systemic inflammatory response and hundreds of thousands of leukocytes are recruited from the blood to the injured heart. The blood pool of leukocytes is rapidly depleted and urgent re-supply of these cells is needed. Myeloid cells are generated in the bone marrow (BM) and spleen, released into the blood, travel to sites of need, extravasate and accumulate inside tissues to accomplish various functions. In this review we focus on the "leukocyte supply chain" and will separately evaluate different myeloid cell compartments (BM, spleen, blood, heart) in steady state and after MI. Moreover, we highlight the local and systemic kinetics of extracellular factors, chemokines and danger signals involved in the regulation of production/generation, release, transportation, uptake, and activation of myeloid cells during the inflammatory phase of MI.

Managing Covid-19 in patients with heart failure: current status and future prospects

INTRODUCTION

COVID-19 may contribute to decompensation of previously stable chronic HF or cause a de-novo heart failure, which may come from the hyperinflammatory response and subsequent increase in metabolic demand.

AREAS COVERED

Two independent investigators searched MEDLINE (via PubMed), Europe PMC, and ScienceDirect databases with the following search terms: COVID-19, heart failure, COVID-19 drugs, heart failure drugs, and device therapy. All of the included full-text articles were rigorously evaluated by both authors in case there was disagreement about whether research should be included or not. In total, 157 studies were included and underwent extensive reading by the authors.

EXPERT OPINION

The World Health Organization (WHO) and the National Institute of Health (NIH) have published COVID-19 drug recommendations, although recommendations for HF-specific drug choices in COVID-19 are still lacking. We hope that this review can answer the void of comprehensive research data regarding the management options of HF in the COVID-19 condition so that clinicians can at least choose a more beneficial therapy or avoid combination therapies that have a high burden of side effects on HF; thus, morbidity and mortality in COVID-19 patients with HF may be reduced.

IL-6 inhibitors effectively reverse post-infarction cardiac injury and ischemic myocardial remodeling via the TGF-β1/Smad3 signaling pathway

Approximately one in four myocardial infarctions occur in older patients. The majority of therapeutic advances are either not appropriate or not tested in elderly patients. The main reasons for deviating from the guidelines are justified concerns regarding the effectiveness of the recommended forms of therapy, fear of adverse drug reactions and ethical concerns. Targeting interleukin 6 (IL-6) for ventricular remodeling after cardiovascular damage is a feasible alternative to standard polypharmaceutics, but the underlying molecular mechanisms are not well understood. Continuous activation of the IL-6-associated cytokine receptor gp130 leads to cardiomyopathic hypertrophy. TGFβ1 is involved in forming fibrosis in various organs, and its overexpression can cause myocardial hypertrophy and fibrosis. Il-6 has been hypothesized to be indirectly involved in cardiac remodeling via the TGFβ1/Smad signaling transduction pathway. In the present study, a rat model of acute myocardial ischemia, IL-6 and IL-6 receptor blockers were injected directly into the necrotic myocardium. Changes in cardiac function, myocardial infarction area, myocardial collagen, necrotic myocardial fibrosis and levels of TGFβ1, IL-6 and MMP2/9 were quantified in myocardial tissue fibrosis by ELISA. The present study demonstrated that IL-6 stimulated myocardial fibrosis through the TGFβ1-Smad-MM2/9 signaling transduction pathway. Overall, this provided a solid foundation for understanding the relationship between IL-6 and ventricular remodeling.

Meta-analysis reveals inhibition of the inflammatory cytokine IL-6 affords limited protection post-myocardial ischemia/infarction

Background

Proinflammatory cytokine cascades play crucial roles in the onset and progression of myocardial ischemia and infarction. Clinically, elevated serum levels of pro-inflammatory cytokine interleukin-6 is a poor prognostic indicator for future cardiac events and cardiac morbidity. Despite several reports, there is no clear evidence of cardiac benefits of inhibiting IL-6 in pre-clinical and clinical settings.

Objective

To analyze the available data systematically and perform a meta-analysis to show the evidence of effects of IL-6 inhibition on cardiac remodeling and mortality in ischemic animal models.

Methods

We used PICO framework and the quality of the studies was assessed using SYRCLE's risk of bias tool. Studies with interventions i.e., genetic deletion or pharmacological inhibition of IL-6/IL-6R were included for the meta-analysis. Systematic review was synthesized by including pre-clinical as well as randomized clinical trials involving myocardial infarction patients treated with IL-6 inhibitors. The effect size of the pooled data was determined using standard mean difference and 95% confidence intervals.

Results

A total of 12 pre-clinical studies were included in the review for analysis. Most of the studies showed an unclear risk of bias as the selection and reporting criteria were poorly described. We observed high heterogeneity in the included studies due to the varying duration of myocardial infarction and the dosage of IL-6 antibodies used in the studies. Overall inhibition of IL-6 significantly increased area at risk [p = 0.001, SMD = 0.49 (95% CI: -0.36, 1.35)] and significantly reduced ejection fraction [p = 0.001, SMD = -0.19 (95% CI: -1.39, 1.01)] and end-diastolic diameter [p = 0.02, SMD = -0.25 (95% CI: -0.87, 0.36)] of left ventricle post-MI, but no effects on infarct size [p < 0.01, SMD = 0.00; 95% CI: -1.34, 0.58). In randomized clinical trials, the overall effect on C-reactive protein remains significantly unchanged on CRP levels (SMD = -0.38; 95% CI: -1.94, 0.55) post-treatment with IL-6R inhibitor tocilizumab. The meta-regression demonstrates a significant positive correlation (p = 0.058) between the increase in ischemic area and duration of ischemia post-surgery in the absence of IL-6. This meta-analysis indicates mixed effect of IL-6 inhibition on cardiac remodeling post-MI, particularly in protecting the myocardium viability from damaging acute inflammation but not significant on cardiac function of ischemic animal models.

Conclusion

Despite the well-established pro-inflammatory nature of IL-6 in myocardial ischemia, our meta-analysis reports a limited contribution of IL-6 in the cardiac remodeling of hearts in animal models of myocardial ischemia. Moreover, genetically deleted IL-6 murine models produced contrasting results. Additional pre-clinical studies exploring the pharmacological inhibition of IL-6R are required to determine the beneficial effects of IL-6 inhibitors in regulating cardiac remodeling. The findings from IL-6R inhibition have better clinical relevance compared to genetically inhibited IL-6.

Aib1 deficiency exacerbates inflammatory responses in acute myocardial infarction mice

Acute myocardial infarction (AMI) is one of the major causes of death throughout the world, while inflammation has been known as a major contributor to the pathophysiology of AMI. Inhibition of inflammation is shown to protect from AMI. Amplified in breast 1 (Aib1) is a transcriptional coactivator protein which can suppress inflammation. The anti-inflammatory activities of Aib1 imply its potential effects against AMI; however, to date the role of Aib1 in AMI has not been described yet. Here we explored the potential functions of Aib1 in AMI. We induced AMI in both wild-type (WT) and Aib1^-/- mice. The expression levels of Aib1 and inflammatory cytokines in the AMI WT mice were measured by RT-PCR and Western blot. The heart infarction area and cardiac functions were compared between the AMI WT and Aib1^-/- mice. The expression levels of inflammatory cytokines including IL-6, IL-1β, TNF-α, and MCP-1 in heart tissues were compared between the AMI WT and Aib1^-/- mice by ELISA and RT-PCR. AMI induced the production of inflammatory cytokines whereas suppressed the expression of Aib1 in WT mice. AMI Aib1^-/- mice displayed increased infarct area and aggravated heart dysfunction, as well as upregulated levels of Il-6, Il-1β, Tnf-α, and Mcp-1 in heart tissues. Aib1 deficiency exacerbates inflammation in AMI mice. KEY MESSAGES: AMI induced inflammation in the heart tissue of mice. Aib1 knockout exacerbated infarction in AMI mice. Aib1 knockout exacerbated cardiac dysfunction in AMI mice. Aib1 knockout exacerbated inflammation in AMI mice.

Immune and Inflammatory Networks in Myocardial Infarction: Current Research and Its Potential Implications for the Clinic

Despite recent scientific and technological advances, myocardial infarction (MI) still represents a major global health problem, leading to high morbidity and mortality worldwide. During the post-MI wound healing process, dysregulated immune inflammatory pathways and failure to resolve inflammation are associated with maladaptive left ventricular remodeling, progressive heart failure, and eventually poor outcomes. Given the roles of immune cells in the host response against tissue injury, understanding the involved cellular subsets, sources, and functions is essential for discovering novel therapeutic strategies that preserve the protective immune system and promote optimal healing. This review discusses the cellular effectors and molecular signals across multi-organ systems, which regulate the inflammatory and reparative responses after MI. Additionally, we summarize the recent clinical and preclinical data that propel conceptual revolutions in cardiovascular immunotherapy.

Renal Denervation Attenuates Adverse Remodeling and Intramyocardial Inflammation in Acute Myocardial Infarction With Ischemia–Reperfusion Injury

Background

Inhibition of sympathetic activity and renin–angiotensin system with renal denervation (RDN) was proved to be effective in managing refractory hypertension, and improving left ventricular (LV) performance in chronic heart failure. The inhibition of sustained sympathetic activation prevents or delays the development of cardiac fibrosis and dysfunction that occurs after myocardial infarction and ischemia–reperfusion (I/R) injury. The translational efficiency of RDN remains to be defined in preclinical animal studies.

Objectives

This study investigated the therapeutic role of RDN in adverse remodeling and intramyocardial inflammation in myocardial ischemia–reperfusion (MI/R) injury.

Methods

Herein, 15 minipigs were subjected to 90-min percutaneous occlusion of the left anterior descending artery followed by reperfusion. Eight animals received simultaneous RDN using catheter-based radiofrequency ablation (MI/R-RDN). Cardiac function and infarct volume were measured in vivo, followed by histological and biochemical analyses.

Results

The infarct volume in I/R-RDN pigs reduced at 30 days postreperfusion, compared to I/R-Sham animals. The levels of catecholamine and cytokines in the serum, kidney cortex, the border, and infarcted regions of the heart were significantly reduced in I/R-RDN group. Moreover, the gene expression of collagen and the protein expression of adrenergic receptor beta 1 in heart were also decreased in I/R-RDN mice. Additionally, RDN therapy alleviated myocardial oxidative stress.

Conclusion

RDN is an effective therapeutic strategy for counteracting postreperfusion myocardial injury and dysfunction, and the application of RDN holds promising prospects in clinical practice.

Pathophysiology of Heart Failure: A Role for Peripheral Blood Mononuclear Cells Mitochondrial Dysfunction?

Heart failure (HF) is a leading cause of hospitalization in patients aged more than 65 years and is associated with high mortality rates. A better comprehension of its physiopathology is still needed, and, in addition to neurohormonal systems and sodium glucose co-transporter 2 modulations, recent studies focus on the mitochondrial respiration of peripheral blood circulating cells (PBMCs). Thus, cardiovascular metabolic risk factors and cellular switch with an increased neutrophil/lymphocytes ratio might favor the decreased PBMC mitochondrial respiration observed in relation with HF severity. PBMCs are implicated in the immune system function and mitochondrial dysfunction of PBMC, potentially induced by their passage through a damaged heart and by circulating mitoDAMPs, which can lead to a vicious circle, thus sustaining negative cardiac remodeling during HF. This new approach of HF complex pathophysiology appears to be a promising field of research, and further studies on acute and chronic HF with reduced or preserved LVEF are warranted to better understand whether circulating PBMC mitochondrial function and mitoDAMPs follow-ups in HF patients might show diagnosis, prognosis or therapeutic usefulness.

Pro-inflammatory cytokines as emerging molecular determinants in cardiolaminopathies

Mutations in Lamin A/C gene (lmna) cause a wide spectrum of cardiolaminopathies strictly associated with significant deterioration of the electrical and contractile function of the heart. Despite the continuous flow of biomedical evidence, linking cardiac inflammation to heart remodelling in patients harbouring lmna mutations is puzzling. Therefore, we profiled 30 serum cytokines/chemokines in patients belonging to four different families carrying pathogenic lmna mutations segregating with cardiac phenotypes at different stages of severity (n = 19) and in healthy subjects (n = 11). Regardless lmna mutation subtype, high levels of circulating granulocyte colony‐stimulating factor (G‐CSF) and interleukin 6 (IL‐6) were found in all affected patients’ sera. In addition, elevated levels of Interleukins (IL) IL‐1Ra, IL‐1β IL‐4, IL‐5 and IL‐8 and the granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) were measured in a large subset of patients associated with more aggressive clinical manifestations. Finally, the expression of the pro‐inflammatory 70 kDa heat shock protein (Hsp70) was significantly increased in serum exosomes of patients harbouring the lmna mutation associated with the more severe phenotype. Overall, the identification of patient subsets with overactive or dysregulated myocardial inflammatory responses could represent an innovative diagnostic, prognostic and therapeutic tool against Lamin A/C cardiomyopathies.

Interleukin-6: A Novel Target for Cardio-Cerebrovascular Diseases

Cardio-Cerebrovascular Disease is a collective term for cardiovascular disease and cerebrovascular disease, being a serious threat to human health. A growing number of studies have proved that the content of inflammatory factors or mediators determines the stability of vascular plaque and the incidence of cardio-cerebrovascular event, and involves in the process of Cardio-Cerebrovascular Diseases. Interleukin-6 is a widely used cytokine that causes inflammation and oxidative stress, which would further result in cardiac and cerebral injury. The increased expression of interleukin-6 is closely related to atherosclerosis, myocardial infarction, heart failure and ischemic stroke. It is a key risk factor for these diseases by triggering inflammatory reaction and inducing other molecules release. Therefore, interleukin-6 may become a potential target for Cardio-Cerebrovascular Diseases in the future. This paper is aimed to discuss the expression changes and pathological mechanisms of interleukin-6 in Cardio-Cerebrovascular Diseases, and to provide a novel strategy for the prevention and treatment of Cardio-Cerebrovascular Diseases.

Micro- and nanoscale biophysical cues for cardiovascular disease therapy

After cardiovascular injury, numerous pathological processes adversely impact the homeostatic function of cardiomyocyte, macrophage, fibroblast, endothelial cell, and vascular smooth muscle cell populations. Subsequent malfunctioning of these cells may further contribute to cardiovascular disease onset and progression. By modulating cellular responses after injury, it is possible to create local environments that promote wound healing and tissue repair mechanisms. The extracellular matrix continuously provides these mechanosensitive cell types with physical cues spanning the micro- and nanoscale to influence behaviors such as adhesion, morphology, and phenotype. It is therefore becoming increasingly compelling to harness these cell-substrate interactions to elicit more native cell behaviors that impede cardiovascular disease progression and enhance regenerative potential. This review discusses recent in vitro and preclinical work that have demonstrated the therapeutic implications of micro- and nanoscale biophysical cues on cell types adversely affected in cardiovascular diseases - cardiomyocytes, macrophages, fibroblasts, endothelial cells, and vascular smooth muscle cells.

Interleukin-6 Signaling and Anti-Interleukin-6 Therapeutics in Cardiovascular Disease

IL (interleukin)-6 is a pivotal cytokine of innate immunity, which enacts a broad set of physiological functions traditionally associated with host defense, immune cell regulation, proliferation, and differentiation. Following recognition of innate immune pathways leading from the NLRP3 (NOD-, LRR-, and pyrin domain-containing protein 3) inflammasome to IL-1 to IL-6 and on to the hepatically derived clinical biomarker CRP (C-reactive protein), an expanding literature has led to understanding of the proatherogenic role for IL-6 in cardiovascular disease and thus the potential for IL-6 inhibition as a novel method for vascular protection. In this review, we provide an overview of the mechanisms by which IL-6 signaling occurs and how that impacts upon pharmacological inhibition; describe murine models of IL-6 and atherogenesis; summarize human epidemiological data outlining the utility of IL-6 as a biomarker of vascular risk; outline genetic data suggesting a causal role for IL-6 in systemic atherothrombosis and aneurysm formation; and then detail the potential role of IL-6 inhibition in stable coronary disease, acute coronary syndromes, heart failure, and the atherothrombotic complications associated with chronic kidney disease and end-stage renal failure. Finally, we review anti-inflammatory and antithrombotic findings for ziltivekimab, a novel IL-6 ligand inhibitor being developed specifically for use in atherosclerotic disease and poised to be tested formally in a large-scale cardiovascular outcomes trial focused on individuals with chronic kidney disease and elevated levels of CRP, a population at high residual atherothrombotic risk, high residual inflammatory risk, and considerable unmet clinical need.

Selective Interleukin-6 Trans-Signaling Blockade Is More Effective Than Panantagonism in Reperfused Myocardial Infarction

Interleukin (IL)-6 is an emerging therapeutic target in myocardial infarction (MI). IL-6 has 2 distinct signaling pathways: trans-signaling, which mediates inflammation, and classic signaling, which also has anti-inflammatory effects. The novel recombinant fusion protein sgp130Fc achieves exclusive trans-signaling blockade, whereas anti-IL-6 antibodies (Abs) result in panantagonism. In a rat model of reperfused MI, sgp130Fc, but not anti-IL-6-Ab, attenuated neutrophil and macrophage infiltration into the myocardium, reduced infarct size, and preserved cardiac function 28 days after MI. These data demonstrate the efficacy of exclusive IL-6 trans-signaling blockade and support further investigation of sgp130Fc as a potential novel therapy in MI.

Post-ischemic Myocardial Inflammatory Response: A Complex and Dynamic Process Susceptible to Immunomodulatory Therapies

Following acute occlusion of a coronary artery causing myocardial ischemia and implementing first-line treatment involving rapid reperfusion, a dynamic and balanced inflammatory response is initiated to repair and remove damaged cells. Paradoxically, restoration of myocardial blood flow exacerbates cell damage as a result of myocardial ischemia-reperfusion (MI-R) injury, which eventually provokes accelerated apoptosis. In the end, the infarct size still corresponds to the subsequent risk of developing heart failure. Therefore, true understanding of the mechanisms regarding MI-R injury, and its contribution to cell damage and cell death, are of the utmost importance in the search for successful therapeutic interventions to finally prevent the onset of heart failure. This review focuses on the role of innate immunity, chemokines, cytokines, and inflammatory cells in all three overlapping phases following experimental, mainly murine, MI-R injury known as the inflammatory, reparative, and maturation phase. It provides a complete state-of-the-art overview including most current research of all post-ischemic processes and phases and additionally summarizes the use of immunomodulatory therapies translated into clinical practice.

Unraveling the thread of uncontrolled immune response in COVID-19 and STEMI: an emerging need for knowledge sharing

The outbreak of severe acute respiratory syndrome coronavirus 2 that first emerged in Wuhan in December 2019 has resulted in the devastating pandemic of coronavirus disease 2019, creating an emerging need for knowledge sharing. Meanwhile, myocardial infarction is and will probably remain the foremost cause of death in the Western world throughout the coming decades. Severe deregulation of the immune system can unnecessarily expand the inflammatory response and participate in target and multiple organ failure, in infection but also in critical illness. Indeed, the course and fate of inflammatory cells observed in severe ST-elevation myocardial infarction (neutrophilia, monocytosis, and lymphopenia) almost perfectly mirror those recently reported in severe coronavirus disease 2019. A pleiotropic proinflammatory imbalance hampers adaptive immunity in favor of uncontrolled innate immunity and is associated with poorer structural and clinical outcomes. The goal of the present review is to gain greater insight into the cellular and molecular mechanisms underlying this canonical activation and downregulation of the two arms of the immune response in both entities, to better understand their pathophysiology and to open the door to innovative therapeutic options. Knowledge sharing can pave the way for therapies with the potential to significantly reduce mortality in both infectious and noninfectious scenarios.

The innate immune response in myocarditis

Acute myocarditis is an inflammatory condition of the heart characterised by cellular injury and the influx of leucocytes, including neutrophils, monocytes, macrophages and lymphocytes. While this response is vital for tissue repair, excessive scar deposition and maladaptive ventricular remodelling can result in a legacy of heart failure. It is increasingly recognised as a clinical phenomenon due, in part, to increased availability of cardiac magnetic resonance imaging in patients presenting with chest pain in the absence of significant coronary artery disease. Emerging epidemiological evidence has associated myocarditis with poor outcomes in the context of left ventricular impairment, and even when the left ventricle is preserved outcomes are less benign than once thought. Despite this, our understanding of the contribution of the inflammatory response to the pathophysiology of acute myocarditis lags behind that of acute myocardial infarction, which is the vanguard cardiovascular condition for inflammation research. We recently reviewed monocyte and macrophage phenotype and function in acute myocardial infarction, concluding that their plasticity and heterogeneity might account for conflicting evidence from attempts to target specific leucocyte subpopulations. Here, we revise our understanding of myocardial inflammation, which is predominantly derived from myocardial infarction research, review experimental evidence for the immune response in acute myocarditis, focusing on innate immunity, and discuss potential future directions for immunotherapy research in acute myocarditis.

Anti-inflammatory Therapy for Coronary Atherosclerotic Heart Disease: Unanswered Questions Behind Existing Successes

Coronary atherosclerotic heart disease is a serious threat to human health. The results of the Canakinumab Anti-Inflammatory Thrombosis Outcome Study published in 2017 put an end to the perennial debate about the anti-inflammatory treatment of coronary atherosclerotic heart disease. In addition to interleukin 1β monoclonal antibody, interleukin 6 receptor antagonists and colchicine have also shown exciting results in clinical trials within the last 3 years. However, behind these successes, questions remain that need to be addressed. In this review, we summarize the successes and existing doubts of interleukin 1β antibodies, interleukin 6 receptor antagonists, and colchicine in the anti-inflammatory treatment of coronary atherosclerotic heart disease.

Hypoxia-inducible factor 2-alpha-dependent induction of IL-6 protects the heart from ischemia/reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI) results in increased myocardial infarct size and leads to poor clinical outcomes. Hypoxia-inducible factor 2-alpha (HIF2α) exerts myocardial protective effects during MIRI through as yet unclear mechanisms. Here, we show that knockdown of HIF2α with cardiotropic recombinant adeno-associated virus serotype 9 (rAAV9) in mouse hearts significantly increased the infarct sizes during myocardial ischemia/reperfusion (MI/R). In addition, HIF2α transcriptionally regulated the expression of interleukin 6 (IL-6) in cardiomyocytes to elicit cardioprotection. Likewise, IL-6 deficiency aggravated MIRI, while treatment with recombinant IL-6 had cardioprotective effects and rescued the mice with HIF2α knockdown. Furthermore, IL-6 treatment significantly activated the PI3K/Akt and STAT3 signaling pathways in the myocardium during MI/R, and the specific inhibitors wortmannin (specific phosphoinositide 3-kinase inhibitor) and Stattic (specific STAT3 inhibitor) substantially abolished HIF2α/IL-6-induced cardioprotection. These studies suggest that HIF2α transcription regulates the expression of IL-6 in cardiomyocytes and plays a protective role during MI/R.

Systemic Inflammatory Burden Correlates with Severity and Predicts Outcomes in Patients with Cardiogenic Shock Supported by a Percutaneous Mechanical Assist Device

In-hospital mortality associated with cardiogenic shock (CS) remains high despite introduction of mechanical circulatory support. In this study, we aimed to investigate whether systemic inflammation is associated with clinical outcomes in CS. We retrospectively analyzed systemic cytokine levels and the neutrophil-to-lymphocyte ratio (NLR), a marker of low-grade inflammation, among 134 patients with CS supported by VA-ECMO or Impella. Sixty-one percent of patients survived CS and either underwent device explantation or were bridged to LVAD or cardiac transplant. IL6 was the predominant circulating cytokine. IL6 levels were reduced after circulatory support in survivors. NLR pre-device implantation was significantly lower in patients with earlier stages of cardiogenic shock. Compared with non-survivors, survivors had a lower pre-device NLR and NLR was independently predictive of survival after adjusting for other covariates. In summary, NLR is a widely available marker of inflammation and correlates with in-hospital mortality among patients with cardiogenic shock requiring percutaneous mechanical circulatory support.

Graphical Abstract

Extracellular miR-146a-5p Induces Cardiac Innate Immune Response and Cardiomyocyte Dysfunction

Previous studies have demonstrated that transient myocardial ischemia leads to release of cellular nucleic acids such as RNA. Extracellular RNA reportedly plays a pivotal role in myocardial inflammation and ischemic injury in animals. RNA profiling has identified that numerous microRNA (miRNAs), such as ss-miR-146a-5p, are upregulated in plasma following myocardial ischemia, and certain uridine-rich miRNAs exhibit strong proinflammatory effects in immune cells via ssRNA-sensing mechanism. However, the effect of extracellular miRNAs on myocardial inflammation and cardiac cell function remains unknown. In this study, we treated adult mouse cardiomyocytes with miR-146a-5p loaded in extracellular vesicles and observed a dose- and TLR7-dependent production of CXCL-2, IL-6, and TNF-α. In vivo, a single dose of myocardial injection of miR-146a-5p induced both cytokine expression (CXCL2, IL-6, and TNF-α) and innate immune cell activation (CD45⁺ leukocytes, Ly6C^mid+ monocytes, Ly6G⁺ neutrophils), which was significantly attenuated in the hearts of TLR7 KO mice. We discovered that conditioned media from miR-146a-treated macrophages stimulated proinflammatory cytokine production in adult cardiomyocytes and significantly inhibited their sarcomere shortening. Finally, using an electric cell impedance-sensing assay, we found that the conditioned media from miR-146a-treated cardiac fibroblasts or cardiomyocytes impaired the barrier function of coronary artery endothelial cells. Taken together, these data demonstrate that extracellular miR-146a-5p activates multiple cardiac cells and induces myocardial inflammation and cardiomyocyte dysfunction via intercellular interaction and innate immune TLR7 nucleic acid sensing.

Inflammatory Cytokines and Chemokines as Therapeutic Targets in Heart Failure

Heart failure exhibits remarkable pathophysiologic heterogeneity. A large body of evidence suggests that regardless of the underlying etiology, heart failure is associated with induction of cytokines and chemokines that may contribute to the pathogenesis of adverse remodeling, and systolic and diastolic dysfunction. The pro-inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1, and IL-6 have been extensively implicated in the pathogenesis of heart failure. Inflammatory cytokines modulate phenotype and function of all myocardial cells, suppressing contractile function in cardiomyocytes, inducing inflammatory activation in macrophages, stimulating microvascular inflammation and dysfunction, and promoting a matrix-degrading phenotype in fibroblasts. Moreover, cytokine-induced growth factor synthesis may exert chronic fibrogenic actions contributing to the pathogenesis of heart failure with preserved ejection fraction (HFpEF). In addition to their role in adverse cardiac remodeling, some inflammatory cytokines may also exert protective actions on cardiomyocytes under conditions of stress. Chemokines, such as CCL2, are also upregulated in failing hearts and may stimulate recruitment of pro-inflammatory leukocytes, promoting myocardial injury, fibrotic remodeling, and dysfunction. Although experimental evidence suggests that cytokine and chemokine targeting may hold therapeutic promise in heart failure, clinical translation remains challenging. This review manuscript summarizes our knowledge on the role of TNF-α, IL-1, IL-6, and CCL2 in the pathogenesis of heart failure, and discusses the promises and challenges of targeted anti-cytokine therapy. Dissection of protective and maladaptive cellular actions of cytokines in the failing heart, and identification of patient subsets with overactive or dysregulated myocardial inflammatory responses are required for design of successful therapeutic approaches.

Targeted pharmacotherapy for ischemia reperfusion injury in acute myocardial infarction

INTRODUCTION

Achieving reperfusion immediately after acute myocardial infarction improves outcomes; despite this, patients remain at a high risk for mortality and morbidity at least for the first year after the event. Ischemia-reperfusion injury (IRI) has a complex pathophysiology and plays an important role in myocardial tissue injury, repair, and remodeling.

AREAS COVERED

In this review, the authors discuss the various mechanisms and their pharmacological agents currently available for reducing myocardial ischemia-reperfusion injury (IRI). They review important original investigations and trials in various clinical databases for treatments targeting IRI.

EXPERT OPINION

Encouraging results observed in many preclinical studies failed to show similar success in attenuating myocardial IRI in large-scale clinical trials. Identification of critical risk factors for IRI and targeting them individually rather than one size fits all approach should be the major focus of future research. Various newer therapies like tocilizumab, anakinra, colchicine, revacept, and therapies targeting the reperfusion injury salvage kinase pathway, survivor activating factor enhancement, mitochondrial pathways, and angiopoietin-like peptide 4 hold promise for the future.

Both Low and High Postprocedural hsCRP Associate with Increased Risk of Death in Acute Coronary Syndrome Patients Treated by Percutaneous Coronary Intervention

BACKGROUND

Inflammation poses dual effects after myocardial infarction, but robust evidence shows that high-sensitivity C-reactive protein (hsCRP), as an inflammatory marker, is constantly associated with worse outcomes. This study is aimed at investigating the probable nonlinear association between postprocedural hsCRP and mortality in patients with acute coronary syndromes (ACS) treated by percutaneous coronary intervention (PCI).

METHODS

A total of 3940 consecutive ACS patients treated by PCI with postprocedural hsCRP measurements were retrospectively recruited. Patients were stratified into 5 groups according to quintiles of hsCRP. Cox regression with adjustments for multiple covariates was used for outcome analysis. Restricted cubic spline (RCS) analysis was used to allow possible nonlinear associations. The primary outcome was all-cause death.

RESULTS

During a median follow-up of 727 days, mortality occurred in 207 (5.3%) patients. Adjusted hazard ratio (HR) was higher in the lowest (<2.26 mg/L, HR: 1.90, 95% confidence interval (CI): 1.08-3.33; P = 0.025), second highest (10.16-12.56 mg/L, HR: 1.86, 95% CI: 1.09-3.16; P = 0.023), and highest quintiles (≥12.56 mg/L, HR: 2.02, 95% CI: 1.21-3.36; P = 0.007) of postprocedural hsCRP, compared to the second lowest quintile (2.26-4.85 mg/L). RCS analysis depicted a J-shaped association between postprocedural hsCRP and mortality (P for nonlinearity = 0.004). Similar association was observed between hsCRP and cardiac death (P for nonlinearity = 0.014), but not for noncardiac mortality (P for nonlinearity = 0.228).

CONCLUSIONS

Both low and high postprocedural hsCRP were associated with higher risk of death in ACS patients treated by PCI.

β2-adrenergic stimulation induces interleukin-6 by increasing Arid5a, a stabilizer of mRNA, through cAMP/PKA/CREB pathway in cardiac fibroblasts

BACKGROUND AND PURPOSE

In cardiovascular diseases, cardiac fibroblasts (CFs) participate in the myocardial inflammation by producing pro-inflammatory cytokines, worsening the prognosis. β2-adrenergic receptor (AR) and β3AR are expressed in CFs, and β-adrenergic stimulation promotes CFs to produce pro-inflammatory cytokines. However, the mechanism of the expression of pro-inflammatory cytokines in response to β-adrenergic stimulation remains to be fully elucidated.

EXPERIMENTAL APPROACH

CFs were isolated from adult wild-type or AT-rich interactive domain-containing protein 5A (Arid5a) knockout mice. The expression of mRNA was measured by real-time RT-PCR. Interleukin (IL)-6 protein was measured by ELISA. The activity of nuclear factor-κB (NF-κB) and cyclic AMP (cAMP) response element binding protein (CREB) was assessed by ELISA-like assay or Western blotting.

KEY RESULTS

The β-adrenergic stimulation remarkably induced IL-6 mRNA and protein through β2AR in CFs. The activation of adenylate cyclase and the enhancement of intracellular cAMP resulted in the upregulation of IL-6 mRNA expression. The induction of IL-6 transcript by β2AR signaling was independent of NF-κB. Concomitant with IL-6, the expression of Arid5a, an IL-6 mRNA stabilizing factor, was enhanced by β2-adrenergic stimulation and by cAMP increase. Importantly, β2AR signaling-mediated IL-6 induction was suppressed in Arid5a knockout CFs. Finally, β2AR stimulation phosphorylated CREB via PKA pathway, and the activation of CREB was essential for the induction of Arid5a and IL-6 mRNA.

CONCLUSION AND IMPLICATIONS

β2-adrenergic stimulation post-transcriptionally upregulates the expression of IL-6 by the induction of Arid5a through cAMP/PKA/CREB pathway in adult CFs. β2AR/Arid5a/IL-6 axis could be a therapeutic target against cardiac inflammation.

Investigation of the underlying hub genes and mechanisms of reperfusion injury in patients undergoing coronary artery bypass graft surgery by integrated bioinformatic analyses

Background

Although coronary artery bypass graft (CABG) surgery is the main method to revascularize the occluded coronary vessels in coronary artery diseases, the full benefits of the operation are mitigated by ischemia-reperfusion (IR) injury. Although many studies have been devoted to reducing IR injury in animal models, the translation of this research into the clinical field has been disappointing. Our study aimed to explore the underlying hub genes and mechanisms of IR injury.

Methods

A weighted gene co-expression network analysis (WGCNA) was executed based on the expression profiles in patients undergoing CABG surgery (GSE29396). Functional annotation and protein-protein interaction (PPI) network construction were executed within the modules of interest. Potential hub genes were predicted, combining both intramodular connectivity (IC) and degrees. Meanwhile, potential transcription factors (TFs) and microRNAs (miRNAs) were predicted by corresponding bioinformatics tools.

Results

A total of 336 differentially expressed genes (DEGs) were identified. DEGs were mainly enriched in neutrophil activity and immune response. Within the modules of interest, 5 upregulated hub genes (IL-6, CXCL8, IL-1β, MYC, PTGS-2) and 6 downregulated hub genes (C3, TIMP1, VSIG4, SERPING1, CD163, and HP) were predicted. Predicted miRNAs (hsa-miR-333-5p, hsa-miR-26b-5p, hsa-miR-124-3p, hsa-miR-16-5p, hsa-miR-98-5p, hsa-miR-17-5p, hsa-miR-93-5p) and TF (STAT1) might have regulated gene expression in the most positively related module, while hsa-miR-333-5p and HSF-1 were predicted to regulate the genes within the most negatively related module.

Conclusions

Our study illustrates an overview of gene expression changes in human atrial samples from patients undergoing CABG surgery and might help translate future research into clinical work.

Immune response mediates the cardiac damage after subarachnoid hemorrhage

Cardiac dysfunction is a common adverse effect of subarachnoid hemorrhage (SAH). Autopsy of SAH patients shows immunocyte infiltration into the heart. In this study, a SAH model of endovascular perforation was performed in adult male mice in order to test whether SAH causes cardiac dysfunction in non-primary cardiac disease young adult male mice and whether immune response mediates SAH induced cardiac and neurological deficit. Splenectomy was performed on a subpopulation of mice one week prior to induction of the SAH. Neurological functional tests, transthoracic Doppler echocardiography, immunofluorescent staining, and flow cytometry were performed to investigate neurological and cardiac function and immune/inflammatory effects of SAH in mice with or without splenectomy. We found that SAH significantly induces ventricular fibrillation and cardiac dysfunction identified by significantly reduced left ventricular ejection fraction, left ventricular fractional shortening, decreased heart rate, as well as increased macrophage and neutrophil infiltration into heart and inflammatory factor expression in the heart compared to sham control mice. SAH also induces neurological deficit, increases astrocyte and microglial activity, and inflammatory cell infiltration into brain as well as up-regulates inflammatory factor expression in the brain tissue. Splenectomy not only significantly improves neurological function, but also reduces cardiac dysfunction compared to SAH alone mice. Splenectomy in SAH mice significantly reduces inflammatory cell infiltration, and decreases NADPH oxidase-2 and macrophage chemokine protein-1 expression in heart and brain when compared to non-splenectomy SAH mice. Our data suggest that, SAH induces acute cardiac dysfunction in non-primary cardiac disease mice. Secondary immune response may play an important role in mediating brain-heart damage after SAH.

Rationale for the ASSAIL-MI-trial: a randomised controlled trial designed to assess the effect of tocilizumab on myocardial salvage in patients with acute ST-elevation myocardial infarction (STEMI)

Introduction

Interleukin-6 (IL-6) may be involved in ischaemia-reperfusion injury and myocardial remodelling after myocardial infarction (MI). We have recently shown that IL-6 inhibition by tocilizumab attenuates systemic inflammation and troponin T-release in patients with acute non-ST elevation MI (NSTEMI). Experimental studies suggest that IL-6 inhibition can limit infarct size through anti-inflammatory mechanisms, but this has not been tested in clinical studies. With the ASSessing the effect of Anti-IL-6 treatment in MI (ASSAIL-MI) trial, we aim to examine whether a single administration of the IL-6 receptor antagonist tocilizumab can increase myocardial salvage in patients with acute ST-elevation MI (STEMI).

Methods and analysis

The ASSAIL-MI trial is a randomised, double blind, placebo-controlled trial, conducted at three high-volume percutaneous coronary intervention (PCI) centres in Norway. 200 patients with first-time STEMI presenting within 6 hours of the onset of chest pain will be randomised to receive tocilizumab or matching placebo prior to PCI. The patients are followed-up for 6 months. The primary endpoint is the myocardial salvage index measured by cardiac MRI (CMR) 3–7 days after the intervention. Secondary endpoints include final infarct size measured by CMR and plasma markers of myocardial necrosis. Efficacy and safety assessments during follow-up include blood sampling, echocardiography and CMR.

Ethics and dissemination

Based on previous experience the study is considered feasible and safe. If tocilizumab increases myocardial salvage, further endpoint-driven multicentre trials may be initiated. The ASSAIL-MI trial has the potential to change clinical practice in patients with STEMI.

Registration

Clinicaltrials.gov, identifier NCT03004703.

Arterial Hypertension and Interleukins: Potential Therapeutic Target or Future Diagnostic Marker?

Hypertension as a multifactorial pathology is one of the most important cardiovascular risk factors, affecting up to 30-40% of the general population. Complex immune responses are involved in the inflammatory mechanism of hypertension, with evidence pointing to increased inflammatory mediators even in prehypertensive patients. Increased vascular permeability, thrombogenesis, and fibrosis, effects that are associated with sustained hypertension, could be attributed to chronic inflammation. Chronic inflammation triggers endothelial dysfunction via increased production of ROS through proinflammatory cytokines. Increased serum level of proinflammatory cytokines such as IL-1β, IL-6, IL-8, IL-17, IL-23, TGFβ, and TNFα in hypertensive patients has been associated with either increased blood pressure values and/or end-organ damage. Moreover, some cytokines (i.e., IL-6) seem to determine a hypertensive response to angiotensin II, regardless of blood pressure values. Understanding hypertension as an inflammatory-based pathology gives way to new therapeutic targets. As such, conventional cardiovascular drugs (statins, calcium channels blockers, and ACEIs/ARBs) have shown additional anti-inflammatory effects that could be linked to their blood pressure lowering properties. Moreover, anti-inflammatory drugs (mycophenolate mofetil) have been shown to decrease blood pressure in hypertensive patients or prevent its development in normotensive individuals. Further research is needed to evaluate whether drugs targeting hypertensive-linked proinflammatory cytokines, such as monoclonal antibodies, could become a new therapeutic option in treating arterial hypertension.

Phosphorylation of Hsp20 Promotes Fibrotic Remodeling and Heart Failure

Cardiomyocyte-specific increases in phosphorylated Hsp20 (S16D-Hsp20) to levels similar to those observed in human failing hearts are associated with early fibrotic remodeling and depressed left ventricular function, symptoms which progress to heart failure and early death. The underlying mechanisms appear to involve translocation of phosphorylated Hsp20 to the nucleus and upregulation of interleukin (IL)-6, which subsequently activates cardiac fibroblasts in a paracrine fashion through transcription factor STAT3 signaling. Accordingly, treatment of S16D-Hsp20 mice with a rat anti-mouse IL-6 receptor monoclonal antibody (MR16-1) attenuated interstitial fibrosis and preserved cardiac function. These findings suggest that phosphorylated Hsp20 may be a potential therapeutic target in heart failure.

Association Between Inflammatory Markers and Myocardial Fibrosis

Inflammation promotes adverse ventricular remodeling. T1 mapping has been used to noninvasively assess interstitial myocardial fibrosis. We examined the association of baseline markers of systemic inflammation with interstitial myocardial fibrosis measured by extracellular volume fraction (ECV) and native T1 mapping at 10-year follow-up in the MESA (Multi-Ethnic Study of Atherosclerosis). Seven hundred seventy-two participants had complete baseline data and underwent cardiac magnetic resonance imaging. All analyses were stratified by sex. Multivariable linear regression models were constructed to assess the associations of baseline CRP (C-reactive protein), IL (interleukin)-6, and fibrinogen with native T1 time and ECV. Longer native T1 times and higher percentages of ECV represent increasing myocardial fibrosis. A 1-SD increment of log-transformed IL-6 levels was associated with 0.4% higher ECV in men (β=0.4; P=0.05). CRP and fibrinogen were not associated to ECV. A 1-SD increment in the log-transformed CRP levels was associated with 4.9 ms higher native T1 (β=4.9; P=0.03). In women, the inflammatory markers did not demonstrate association with native T1 nor ECV. Higher IL-6 and CRP levels are associated with increased interstitial myocardial fibrosis assessed by cardiac magnetic resonance in men. However, no inflammatory markers were associated to myocardial fibrosis in women.

Fréquence cardiaque

Les macrophages résidents tissulaires ou ceux qui ont pour origine des monocytes circulants régulent l’homéostasie cardiaque en conditions physiologiques mais aussi pathologiques. La présence de macrophages résidents au sein du nœud auriculo-ventriculaire distal a été révélée par des études récentes réalisées chez la souris et chez l’homme. Ces macrophages expriment la connexine-43, une protéine de jonction intercellulaire, et augmentent la conduction auriculo-ventriculaire en accélérant la repolarisation des cardiomyocytes interconnectés. La compréhension fine et exhaustive du rôle de ces macrophages dans la conduction électrique cardiaque pourrait conduire à de nouvelles approches thérapeutiques reposant sur la modulation des fonctions macrophagiques dans le cœur arythmique.

Cardiomyocytes and Macrophages Discourse on the Method to Govern Cardiac Repair

In response to pathophysiological stress, the cardiac tissue undergoes profound remodeling process that incorporates the elimination of dying resident cells, compensatory hypertrophy of functional cardiomyocytes, growth and remodeling of the vascular compartment and formation of a fibrotic scar. Accumulating evidences indicate that cardiac remodeling is, at least in part, controlled by a complex crosstalk between cardiomyocytes and macrophages. The strategic location of abundant macrophages to the proximity of cardiomyocytes suggest that they could regulate the fate of cardiomyocytes in the injured heart. As such, macrophages appear as critical support cells for cardiomyocytes and play central roles in cardiac hypertrophy, fibrosis and remodeling. Notably, the cardiac tissue expands heterogeneous population of cardiac macrophages through local proliferation of resident macrophage as well as recruitment and differentiation of blood-derived monocytes. It has also been suggested that cardiac-resident macrophages display distinct functional properties from that of monocyte-derived macrophages in cardiac tissue. Furthermore, macrophages are an overflowing source of biological entities with non-canonical roles on cardiac conduction or cardiomyocyte proliferation by regulating action potential diffusion or cardiac cell cycle reentry. Alternatively, stressed cardiomyocytes can trigger the release of a broad repertoire of instructive signals that can regulate macrophage number, skew their phenotype and therefore direct their beneficial or deleterious actions. In this review, we highlight recent discoveries describing how the intricate dialogue between cardiomyocytes and macrophages can shape the deleterious or healing signaling mechanisms in the injured cardiac tissue.

LXR/RXR signaling and neutrophil phenotype following myocardial infarction classify sex differences in remodeling

Sex differences in heart failure development following myocardial infarction (MI) are not fully understood. We hypothesized that differential MI signaling could explain variations in outcomes. Analysis of the mouse heart attack research tool 1.0 (422 mice; young = 5.4 ± 0.1; old = 23.3 ± 0.1 months of age) was used to dissect MI signaling pathways, which was validated in a new cohort of mice (4.8 ± 0.2 months of age); and substantiated in humans. Plasma collected at visit 2 from the MI subset of the Jackson Heart Study (JHS; a community-based study consisting of middle aged and older adults of African ancestry) underwent glycoproteomics grouped by outcome: (1) heart failure hospitalization after visit 2 (n = 3 men/12 women) and (2) without hospitalization through 2012 (n = 24 men/21 women). Compared to young male mice, the infarct region of young females had fewer, but more efficient tissue clearing neutrophils with reduced pro-inflammatory gene expression. Apolipoprotein (Apo) F, which acts upstream of the liver X receptors/retinoid X receptor (LXR/RXR) pathway, was elevated in the day 7 infarcts of old mice compared to young controls and was increased in both men and women with heart failure. In vitro, Apo F stimulated CD36 and peroxisome proliferator-activated receptor (PPAR)γ activation in male neutrophils to turn off NF-κB activation and stimulate LXR/RXR signaling to initiate resolution. Female neutrophils were desensitized to Apo F and instead relied on thrombospondin-1 stimulation of CD36 to upregulate AMP-activated protein kinase, resulting in an overall better wound healing strategy. With age, female mice were desensitized to LXR/RXR signaling, resulting in enhanced interleukin-6 activation, a finding replicated in the JHS community cohort. This is the first report to uncover sex differences in post-MI neutrophil signaling that yielded better outcomes in young females and worse outcomes with age.

Cardiac Remodeling: Endothelial Cells Have More to Say Than Just NO

The heart is a highly structured organ consisting of different cell types, including myocytes, endothelial cells, fibroblasts, stem cells, and inflammatory cells. This pluricellularity provides the opportunity of intercellular communication within the organ, with subsequent optimization of its function. Intercellular cross-talk is indispensable during cardiac development, but also plays a substantial modulatory role in the normal and failing heart of adults. More specifically, factors secreted by cardiac microvascular endothelial cells modulate cardiac performance and either positively or negatively affect cardiac remodeling. The role of endothelium-derived small molecules and peptides—for instance NO or endothelin-1—has been extensively studied and is relatively well defined. However, endothelial cells also secrete numerous larger proteins. Information on the role of these proteins in the heart is scattered throughout the literature. In this review, we will link specific proteins that modulate cardiac contractility or cardiac remodeling to their expression by cardiac microvascular endothelial cells. The following proteins will be discussed: IL-6, periostin, tenascin-C, thrombospondin, follistatin-like 1, frizzled-related protein 3, IGF-1, CTGF, dickkopf-3, BMP-2 and−4, apelin, IL-1β, placental growth factor, LIF, WISP-1, midkine, and adrenomedullin. In the future, it is likely that some of these proteins can serve as markers of cardiac remodeling and that the concept of endothelial function and dysfunction might have to be redefined as we learn more about other factors secreted by ECs besides NO.

Translational overview of cytokine inhibition in acute myocardial infarction and chronic heart failure

Many cytokines are currently under investigation as potential target to improve cardiac function and outcome in the setting of acute myocardial infarction (MI) or chronic heart failure (HF). Here we aim to provide a translational overview of cytokine inhibiting therapies tested in experimental models and clinical studies. In various experimental studies, inhibition of interleukin-1 (IL-1), -6 (IL-6), -8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), CC- and CXC chemokines, and tumor necrosis factor-α (TNF-α) had beneficial effects on cardiac function and outcome. On the other hand, neutral or even detrimental results have been reported for some (IL-1, IL-6, IL-8, and MCP-1). Ambivalence of cytokine function, differences in study designs, treatment regimens and chosen endpoints hamper the translation of experimental research into clinical practice. Human studies are currently limited to IL-1β inhibition, IL-1 receptor antagonists (IL-1RA), IL-6 receptor antagonists (IL-6RA) or TNF inhibition. Despite favorable effects on cardiovascular events observed in retrospective cohort studies of rheumatoid arthritis patients treated with TNF inhibition or IL-1RA, most prospective studies reported disappointing and inconsistent results. Smaller studies (n < 100) generally reported favorable results of anticytokine therapy on cardiac function, but only one of the larger studies (n > 100) evaluating IL-1β inhibition presented positive results on outcome. In conclusion, of the 10 anticytokine therapies tested in animals models beneficial effects have been reported in at least one setting. In larger clinical studies, findings were unsatisfactory in all but one. Many anticytokine therapies with promising animal experimental data continue to require further evaluation in humans.

Interleukin 6-Mediated Endothelial Barrier Disturbances Can Be Attenuated by Blockade of the IL6 Receptor Expressed in Brain Microvascular Endothelial Cells

Compromised blood-brain barrier (BBB) by dysregulation of cellular junctions is a hallmark of many cerebrovascular disorders due to the pro-inflammatory cytokines action. Interleukin 6 (IL6) is implicated in inflammatory processes and in secondary brain injury after subarachnoid hemorrhage (SAH) but its role in the maintenance of cerebral endothelium still requires a precise elucidation. Although IL6 has been shown to exert pro-inflammatory action on brain microvascular endothelial cells (ECs), the expression of one of the IL6 receptors, the IL6R is controversially discussed. In attempt to reach more clarity in this issue, we present here an evident baseline expression of the IL6R in BBB endothelium in vivo and in an in vitro model of the BBB, the cEND cell line. A significantly increased expression of IL6R and its ligand was observed in BBB capillaries 2 days after experimental SAH in mice. In vitro, we saw IL6 administration resulting in an intracellular and extracellular elevation of IL6 protein, which was accompanied by a reduced expression of tight and adherens junctions, claudin-5, occludin, and vascular-endothelial (VE-) cadherin. By functional assays, we could demonstrate IL6-incubated brain ECs to lose their endothelial integrity that can be attenuated by inhibiting the IL6R. Blockade of the IL6R by a neutralizing antibody has reconstituted the intercellular junction expression to the control level and caused a restoration of the transendothelial electrical resistance of the cEND cell monolayer. Our findings add depth to the current understanding of the involvement of the endothelial IL6R in the loss of EC integrity implicating potential therapy options.

Cyclic Nucleotide-Directed Protein Kinases in Cardiovascular Inflammation and Growth

Cardiovascular disease (CVD), including myocardial infarction (MI) and peripheral or coronary artery disease (PAD, CAD), remains the number one killer of individuals in the United States and worldwide, accounting for nearly 18 million (>30%) global deaths annually. Despite considerable basic science and clinical investigation aimed at identifying key etiologic components of and potential therapeutic targets for CVD, the number of individuals afflicted with these dreaded diseases continues to rise. Of the many biochemical, molecular, and cellular elements and processes characterized to date that have potential to control foundational facets of CVD, the multifaceted cyclic nucleotide pathways continue to be of primary basic science and clinical interest. Cyclic adenosine monophosphate (cyclic AMP) and cyclic guanosine monophosphate (cyclic GMP) and their plethora of downstream protein kinase effectors serve ubiquitous roles not only in cardiovascular homeostasis but also in the pathogenesis of CVD. Already a major target for clinical pharmacotherapy for CVD as well as other pathologies, novel and potentially clinically appealing actions of cyclic nucleotides and their downstream targets are still being discovered. With this in mind, this review article focuses on our current state of knowledge of the cyclic nucleotide-driven serine (Ser)/threonine (Thr) protein kinases in CVD with particular emphasis on cyclic AMP-dependent protein kinase (PKA) and cyclic GMP-dependent protein kinase (PKG). Attention is given to the regulatory interactions of these kinases with inflammatory components including interleukin 6 signals, with G protein-coupled receptor and growth factor signals, and with growth and synthetic transcriptional platforms underlying CVD pathogenesis. This article concludes with a brief discussion of potential future directions and highlights the importance for continued basic science and clinical study of cyclic nucleotide-directed protein kinases as emerging and crucial controllers of cardiac and vascular disease pathologies.