Interleukin-1β modulation using a genetically engineered antibody prevents adverse cardiac remodelling following acute myocardial infarction in the mouse

Reduction of mortality, cardiac damage, and cerebral damage by IL-1 inhibition in a murine model of TTP

ABSTRACT

Thrombotic thrombocytopenic purpura (TTP), a rare but fatal disease if untreated, is due to alteration in von Willebrand factor cleavage resulting in capillary microthrombus formation and ischemic organ damage. Interleukin-1 (IL-1) has been shown to drive sterile inflammation after ischemia and could play an essential contribution to postischemic organ damage in TTP. Our objectives were to evaluate IL-1 involvement during TTP and to test the efficacy of the recombinant IL-1 receptor antagonist, anakinra, in a murine TTP model. We retrospectively measured plasma IL-1 concentrations in patients with TTP and controls. Patients with TTP exhibited elevated plasma IL-1α and -1β concentrations, which correlated with disease course and survival. In a mouse model of TTP, we administered anakinra (IL-1 inhibitor) or placebo for 5 days and evaluated the efficacy of this treatment. Anakinra significantly reduced mortality of mice (P < .001). Anakinra significantly decreased TTP-induced cardiac damage as assessed by blood troponin concentrations, evaluation of left ventricular function by echocardiography, [18F]fluorodeoxyglucose positron emission tomography of myocardial glucose metabolism, and cardiac histology. Anakinra also significantly reduced brain TTP-induced damage evaluated through blood PS100b concentrations, nuclear imaging, and histology. We finally showed that IL-1α and -1β trigger endothelial degranulation in vitro, leading to the release of von Willebrand factor. In conclusion, anakinra significantly reduced TTP mortality in a preclinical model of the disease by inhibiting both endothelial degranulation and postischemic inflammation, supporting further evaluations in humans.

Reperfusion Injury in Patients With Acute Myocardial Infarction: JACC Scientific Statement

Despite impressive improvements in the care of patients with ST-segment elevation myocardial infarction, mortality remains high. Reperfusion is necessary for myocardial salvage, but the abrupt return of flow sets off a cascade of injurious processes that can lead to further necrosis. This has been termed myocardial ischemia-reperfusion injury and is the subject of this review. The pathologic and molecular bases for myocardial ischemia-reperfusion injury are increasingly understood and include injury from reactive oxygen species, inflammation, calcium overload, endothelial dysfunction, and impaired microvascular flow. A variety of pharmacologic strategies have been developed that have worked well in preclinical models and some have shown promise in the clinical setting. In addition, there are newer mechanical approaches including mechanical unloading of the heart prior to reperfusion that are in current clinical trials.

Inhibitors of NLRP3 Inflammasome in Ischemic Heart Disease: Focus on Functional and Redox Aspects

Myocardial ischemia-reperfusion injury (MIRI) is caused by several mechanisms, including the production of reactive oxygen species (ROS), altered cellular osmolarity, and inflammatory response. Calcium overload, altered oxygen levels, and mitochondrial ROS are also involved in these MIRI processes, resulting in the irreversible opening of the mitochondrial permeability transition pore (mPTP). These mechanisms and processes are associated with NLRP3 inflammasome priming and activation, which can also induce cell death by pyroptosis through the up-regulation of the caspase-1 pathway and IL-18 release. In addition, endothelial dysfunction, both in the presence and absence of MIRI, is also accompanied by altered oxygen levels, decreased nitric oxide production, and ROS overproduction, resulting in the expression of adhesion molecules and leukocyte infiltration in which the NLRP3 inflammasome plays a central role, thus contributing, through endothelial dysfunction, to the alteration of coronary flow, typical of ischemic heart disease. Given the intricate interrelationship between ROS and NLRP3, ROS inhibitors can reduce NLRP3 inflammasome activation, while NLRP3 inhibitors can reduce oxidative stress and inflammation. NLRP3 inhibitors have been intensively studied as anti-inflammatory agents in basic cardiovascular sciences. In this review, we analyze the interrelation between ROS and NLRP3 in ischemic heart disease and the effects of some NLRP3 inhibitors as possible therapeutic agents in this disease condition. All compounds considered in this review need larger studies to confirm their appropriate use in clinical scenarios as anti-ischemic drugs.

Comparative Roles of IL-1, IL-6, IL-10, IL-17, IL-18, 1L-22, IL-33, and IL-37 in Various Cardiovascular Diseases With Potential Insights for Targeted Immunotherapy

In recent years, the study of interleukins (ILs), crucial cytokines involved in immune response and inflammation, has garnered significant attention within the sphere of cardiovascular diseases (CVDs). The research has provided insights into the involvement of ILs in diverse CVDs, including arrhythmias, myocardial infarction, atherosclerosis, and heart failure (HF). ILs have emerged as promising therapeutic targets for drug interventions through their involvement in disease development and progression. This comprehensive review provides a detailed overview of ILs, elucidating their functions within the immune system and offering insights into their specific contributions to various CVDs. Moreover, the article delves into the examination of current and potential drug therapies that selectively target ILs in the management of CVDs, presenting a comprehensive analysis of the advantages and disadvantages associated with these therapeutic approaches. A comprehensive literature review was conducted to investigate the involvement of ILs in CVDs. The relevant articles were searched on PubMed, PubMed Central, Medline, Cochrane, Google Scholar, and ScienceDirect databases. The search encompassed articles published from these databases' inception until July 12, 2023. We first examine generalized aspects of ILs, particularly CVDs. Then, we shift focus towards examining the direct impact of ILs on cardiac cells and tissue; on the immune system and inflammation; endothelial cells and vascular function; and finally, their interactions with other signaling pathways and molecules. Then, we discuss the molecular mechanisms of various ILs. Sequentially, we delve into a comprehensive analysis of the individualized role of each distinct IL in diverse CVDs, examining their specific contributions. Finally, we explore the potential for targeted drug therapy to modulate IL activity, aiming to enhance outcomes for patients burdened with CVD. The objective is the identification of gaps in current knowledge and highlight areas that require further investigation within the context of cardiovascular medicine. Through deepening our comprehension of the intricate involvement of ILs in CVDs and harnessing their potential for targeted drug therapy, novel treatment strategies can be devised, leading to improved patient outcomes in cardiovascular medicine.

Inflammasomes as mediators of inflammation in HIV-1 infection

Human immunodeficiency virus type 1 (HIV-1) infection is a chronic disease without a known cure. The advent of effective antiretroviral therapy (ART) has enabled people with HIV (PWH) to have significantly prolonged life expectancies. As a result, morbidity and mortality associated with HIV-1 infection have declined considerably. However, these individuals experience chronic systemic inflammation whose multifaceted etiology is associated with other numerous comorbidities. Inflammasomes are vital mediators that contribute to inflammatory signaling in HIV-1 infection. Here, we provide an overview of the inflammatory pathway that underlies HIV-1 infection, explicitly highlighting the role of the NLRP3 inflammasome. We also delineate the current literature on inflammasomes and the therapeutic targeting strategies aimed at the NLRP3 inflammasome to moderate HIV-1 infection-associated inflammation. Here we describe the NLRP3 inflammasome as a key pathway in developing novel therapeutic targets to block HIV-1 replication and HIV-1-associated inflammatory signaling. Controlling the inflammatory pathways is critical in alleviating the morbidities and mortality associated with chronic HIV-1 infection in PWH.

Plausible Role of NLRP3 Inflammasome and Associated Cytokines in Pathogenesis of Rheumatic Heart Disease

Rheumatic heart disease (RHD) is a post-streptococcal sequela caused by Streptococcus pyogenes. The global burden of disease is high among people with low socio-economic status, with significant cases emerging every year despite global eradication efforts. The current treatment includes antibiotic therapies to target strep throat and rheumatic fever and valve replacement strategies as a corrective measure for chronic RHD patients. Valvular damage and valve calcification are considered to be the end-stage processes of the disease resulting from impairment of the endothelial arrangement due to immune infiltration. This immune infiltration is mediated by a cascade of events involving NLRP3 inflammasome activation. NLRP3 inflammasome is activated by wide range of stimuli including bacterial cell wall components like M proteins and leukocidal toxins like nicotinamide dehydrogenase (NADase) and streptolysin O (SLO) and these play a major role in sustaining the virulence of Streptococcus pyogenes and progression of RHD. In this review, we are discussing NLRP3 inflammasome and its plausible role in the pathogenesis of RHD by exploiting the host-pathogen interaction mainly focusing on the NLRP3 inflammasome-mediated cytokines IL-1β and IL-18. Different therapeutic approaches involving NLRP3 inflammasome inactivation, caspase-1 inhibition, and blockade of IL-1β and IL-18 are discussed in this review and may be promising for treating RHD patients.

The role of γδ T17 cells in cardiovascular disease

Due to the ability of γδ T cells to bridge adaptive and innate immunity, γδ T cells can respond to a variety of molecular cues and acquire the ability to induce a variety of cytokines such as IL-17 family, IFN-γ, IL-4, and IL-10. IL-17⁺ γδ T cells (γδ T17 cells) populations have recently received considerable interest as they are the major early source of IL-17A in many immune response models. However, the exact mechanism of γδ T17 cells is still poorly understood, especially in the context of cardiovascular disease (CVD). CVD is the leading cause of death in the world, and it tends to be younger. Here, we offer a review of the cardiovascular inflammatory and immune functions of γδ T17 cells in order to understand their role in CVD, which may be the key to developing new clinical applications.

Rationale and design of interleukin-1 blockade in recently decompensated heart failure (REDHART2): a randomized, double blind, placebo controlled, single center, phase 2 study

Background

Heart failure (HF) is a global leading cause of mortality despite implementation of guideline directed therapy which warrants a need for novel treatment strategies. Proof-of-concept clinical trials of anakinra, a recombinant human Interleukin-1 (IL-1) receptor antagonist, have shown promising results in patients with HF.

Method

We designed a single center, randomized, placebo controlled, double-blind phase II randomized clinical trial. One hundred and two adult patients hospitalized within 2 weeks of discharge due to acute decompensated HF with reduced ejection fraction (HFrEF) and systemic inflammation (high sensitivity of C-reactive protein > 2 mg/L) will be randomized in 2:1 ratio to receive anakinra or placebo for 24 weeks. The primary objective is to determine the effect of anakinra on peak oxygen consumption (VO₂) measured at cardiopulmonary exercise testing (CPX) after 24 weeks of treatment, with placebo-corrected changes in peak VO₂ at CPX after 24 weeks (or longest available follow up). Secondary exploratory endpoints will assess the effects of anakinra on additional CPX parameters, structural and functional echocardiographic data, noninvasive hemodynamic, quality of life questionnaires, biomarkers, and HF outcomes.

Discussion

The current trial will assess the effects of IL-1 blockade with anakinra for 24 weeks on cardiorespiratory fitness in patients with recent hospitalization due to acute decompensated HFrEF.

Trial registration: The trial was registered prospectively with ClinicalTrials.gov on Jan 8, 2019, identifier NCT03797001.

Diabetes mellitus and heart failure: an update on pathophysiology and therapy

Diabetes mellitus (DM) is frequent among heart failure (HF) patients with a further projected increase in prevalence in next years. DM promotes the development of both HF with reduced (HFrEF) and preserved ejection fraction (HFpEF) through different mechanisms. As the general prevalence of both DM and HF is growing worldwide, it is important to define the pathophysiologic mechanisms driving the development of HF in DM patients. These include changes in the cardiac metabolism, mitochondrial dysfunction, impairment in insulin signaling, maladaptive inflammation, coronary microvascular dysfunction, endoplasmic reticulum stress, autophagy suppression, and structural changes, among the main ones. In recent years, novel glucose-lowering treatments, especially sodium-glucose cotransporter 2 inhibitors (SGLT-2is), have shown a strikingly positive impact on the natural history of HF. This has led to a progressive change in choosing SGLT-2is in DM patients at high risk for CV disease, supported by recent guidelines. The knowledge about novel pathophysiological mechanisms linking DM and HF may open the way to the development of new targeted therapies in the future. In this review, we will summarize general aspects dealing with incidence, prevalence, and pathophysiology of DM in HF patients. As well, we discuss the therapeutic targets to reduce the disease burden and the current evidence of glucose-lowering drugs in patients with DM and HF.

Effect of Anti-Rheumatic Drugs on Cardiovascular Disease Events in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by erosive arthritis, which can involve multiple systems. Patients with RA may have a variety of comorbidities, including cardiovascular disease (CVD), lung cancer, lymphoma, infection, osteoporosis, fatigue, depression, colon cancer, breast cancer, prostate cancer, and Alzheimer's disease. Among these comorbidities, the incidence of CVD, lung cancer, lymphoma, infection, and osteoporosis is higher. CVD is a serious complication of RA. The risk of CVD and associated mortality rate in patients with RA is high, and the treatment rate is low. In addition to traditional risk factors, such as age, sex, blood pressure, and diabetes, RA is also associated with inflammation. Furthermore, therapeutic drugs for RA, including non-steroidal anti-inflammatory drugs, glucocorticoids, and disease-modifying anti-rheumatic drugs, have beneficial or harmful effects on cardiovascular events in patients with RA. This article discusses the effects of therapeutic drugs for RA on cardiovascular events.

Cardiomyocyte IL-1R2 protects heart from ischemia/reperfusion injury by attenuating IL-17RA-mediated cardiomyocyte apoptosis

Myocardial ischemia reperfusion (I/R) injury is a complex process with intense inflammatory response and cardiomyocyte apoptosis. As a decoy receptor of IL-1β, Interleukin-1 receptor type 2 (IL-1R2) inhibits IL-1β signaling. However, its role in I/R injury remains unknown. Here we found that the serum levels of IL-1R2 were significantly increased in patients with acute myocardial infarction (AMI) following interventional therapy. Similarly, after myocardial I/R surgery, IL-1R2 expression was significantly increased in heart of wild-type mice. In addition, IL-1R2-deficient mice heart showed enlarged infarct size, increased cardiomyocyte apoptosis together with reduced cardiac systolic function. Following exposure to hypoxia and reoxygenation (H/R), neonatal rat ventricular myocytes (NRVM) significantly increased IL-1R2 expression relying on NF-κB activation. Consistently, IL-1R2-deficient mice increased immune cells infiltrating into heart after surgery, which was relevant with cardiac damage. Additionally, IL-1R2 overexpression in cardiomyocyte protected cardiomyocyte against apoptosis through reducing the IL-17RA expression both in vivo and in vitro. Our results indicate that IL-1R2 protects cardiomyocytes from apoptosis, which provides a therapeutic approach to turn down myocardial I/R injury.

IL-1β promotes hypoxic vascular endothelial cell proliferation through the miR-24-3p/NKAP/NF-kB axis

Purpose: Our previous data indicated that miR-24-3p is involved in the regulation of vascular endothelial cell (EC) proliferation and migration/invasion. However, whether IL-1β affects hypoxic HUVECs by miR-24-3p is still unclear. Therefore, the present study aimed to investigate the role and underlying mechanism of interleukin 1β (IL-1β) in hypoxic HUVECs.

Methods: We assessed the mRNA expression levels of miR-24-3p, hypoxia-inducible factor-1α (HIF1A) and NF-κB-activating protein (NKAP) by quantitative real-time polymerase chain reaction (RT-qPCR). ELISA measured the expression level of IL-1β. Cell counting kit-8 (CCK-8) assays evaluated the effect of miR-24-3p or si-NKAP+miR-24 on cell proliferation (with or without IL-1β). Transwell migration and invasion assays were used to examine the effects of miR-24-3p or si-NKAP+miR-24-3p on cell migration and invasion (with or without IL-1β). Luciferase reporter assays were used to identify the target of miR-24-3p.

Results: We demonstrated that in acute myocardial infarction (AMI) patient blood samples, the expression of miR-24-3p is down-regulated, the expression of IL-1β or NKAP is up-regulated, and IL-1β or NKAP is negatively correlated with miR-24-3p. Furthermore, IL-1β promotes hypoxic HUVECs proliferation by down-regulating miR-24-3p. In addition, IL-1β also significantly promotes the migration and invasion of hypoxic HUVECs; overexpression of miR-24-3p can partially rescue hypoxic HUVECs migration and invasion. Furthermore, we discovered that NKAP is a novel target of miR-24-3p in hypoxic HUVECs. Moreover, both the overexpression of miR-24-3p and the suppression of NKAP can inhibit the NF-κB/pro-IL-1β signaling pathway. However, IL-1β mediates suppression of miR-24-3p activity, leading to activation of the NKAP/NF-κB pathway. In conclusion, our results reveal a new function of IL-1β in suppressing miR-24-3p up-regulation of the NKAP/NF-κB pathway.

Sodium tanshinone IIA sulfonate improves adverse ventricular remodeling post MI by reducing myocardial necrosis, modulating inflammation and promoting angiogenesis

BACKGROUND AND OBJECTIVE

Myocardial infarction (MI) leads to pathological cardiac remodeling and heart failure. Sodium tanshinone IIA sulfonate (STS) shows therapeutic values. The present study aimed to explore the potential role of STS in ventricular remodeling post-MI.

METHODS

Mice were randomly divided into sham, MI + normal saline (NS) and MI + STS (20.8 mg/kg/day intraperitoneally) groups. MI was established following left anterior descending artery ligation. Cardiac function was evaluated using echocardiography. Scar size and myocardial fibrosis-associated markers were detected using Masson's trichrome staining and western blot analysis (WB). Necrosis and inflammation were assessed using H&E staining, lactate dehydrogenase (LDH) detection, ELISA, immunohistochemical staining, and WB. Furthermore, angiogenesis markers and associated proteins were detected using immunohistochemical staining and WB.

RESULTS

Mice treated with STS exhibited significant improvements in cardiac function, smaller scar size, and low expression levels of α-smooth muscle actin and collagen I and III at 28 days following surgery, compared with the NS-treated group. Moreover, treatment with STS reduced eosinophil necrosis, the infiltration of inflammatory cells, plasma levels of LDH, high mobility group protein B1, interleukin-1β and tumor necrosis factor-α, and protein expression of these cytokines at 3 days. Macrophage infiltration was also decreased in the STS group in the early phase. Additionally, CD31+ vascular density, protein levels of hypoxia-inducible factor-1α, and vascular endothelial growth factor were elevated in the STS-treated mice at 28 days.

CONCLUSION

STS improved pathological remodeling post-MI, and the associated therapeutic effects may result from a decrease in myocardial necrosis, modulation of inflammation, and an increase in angiogenesis.

IKKε protects against starvation-induced NLRP3 inflammasome and pyroptosis in H9c2 cells by alleviating mitochondrial injury

The deprivation of myocardial nutrition causes cardiomyocyte death and disturbance of energy metabolism. IKKε plays an important regulatory role in many biological events such as inflammation, redox reaction, cell death, etc. However, the more in-depth mechanism by which IKKε contributes to cardiomyocytes death in nutrition deprivation remains poorly understood. IKKε expression was knocked down by siRNA in H9c2 cells, and cells were cultured under starvation conditions to simulate ischemic conditions. Starvation triggered greater NLRP3 activation, accompanied by more IL-1β, IL-18 and caspase-1 release in the siIKKε H9c2 cells compared with the control H9c2 cells. Western blot and immunofluorescence showed that the IKKε konckdown promoted NLRP3 expressions and ROS release under starvation conditions. Furthermore, electron micrography and JC-1 analysis revealed that IKKε konckdown resulted in aggravated mitochondrial damage and more mitochondrial ROS (mtROS) released in vitro. Notably, Western blot analysis showed that IKKε deficiency activated the TBK1 and IRF3 signaling pathways to promote pyroptosis in vitro. Collectively, our results indicate that IKKε protects against cardiomyocyte injury by reducing mitochondrial damage and NLRP3 expression following nutrition deprivation via regulation of the TBK1/IRF3 signaling pathway. This study further revealed the mechanism of IKKε in inflammation and myocardial nutrition deprivation.

Targeting the NLRP3 inflammasome in cardiovascular diseases

The NACHT, leucine-rich repeat (LRR), and pyrin domain (PYD)-containing protein 3 (NLRP3) inflammasome is an intracellular sensing protein complex that plays a major role in innate immunity. Following tissue injury, activation of the NLRP3 inflammasome results in cytokine production, primarily interleukin(IL)-1β and IL-18, and, eventually, inflammatory cell death - pyroptosis. While a balanced inflammatory response favors damage resolution and tissue healing, excessive NLRP3 activation causes detrimental effects. A key involvement of the NLRP3 inflammasome has been reported across a wide range of cardiovascular diseases (CVDs). Several pharmacological agents selectively targeting the NLRP3 inflammasome system have been developed and tested in animals and early phase human studies with overall promising results. While the NLRP3 inhibitors are in clinical development, multiple randomized trials have demonstrated the safety and efficacy of IL-1 blockade in atherothrombosis, heart failure and recurrent pericarditis. Furthermore, the non-selective NLRP3 inhibitor colchicine has been recently shown to significantly reduce cardiovascular events in patients with chronic coronary disease. In this review, we will outline the mechanisms driving NLRP3 assembly and activation, and discuss the pathogenetic role of the NLRP3 inflammasome in CVDs, providing an overview of the current and future therapeutic approaches targeting the NLRP3 inflammasome.

IRF2 contributes to myocardial infarction via regulation of GSDMD induced pyroptosis

Interferon regulatory factor (IRF) 2 is a transcription factor belonging to the IRF family, which is essential for gasdermin D (GSDMD)‑induced pyroptosis. Decreasing myocardial cell pyroptosis confers protection against heart damage and cardiac dysfunction caused by myocardial infarction (MI). The aim of the present study was to investigate the involvement of IRF2 in MI and the underlying mechanism of IRF2 in pyroptosis. To mimic MI, ligation of the left anterior descending coronary artery was performed to establish an in vivo mouse model and rat cardiomyocytes H9c2 cells were cultured under hypoxic conditions to establish an in vitro model. Transthoracic echocardiography was used to assess cardiac function. Hematoxylin and eosin staining was used to observe histopathological changes in the myocardial tissue. Immunohistochemistry and western blotting were performed to detect IRF2 expression levels. TUNEL staining and flow cytometry were used to detect apoptosis in myocardial tissue and cells. Chromatin immunoprecipitation and dual luciferase reporter assay were used to verify the effect of IRF2 on GSDMD transcription. IRF2 was upregulated in MI mice. MI induced pyroptosis, as evidenced by increased GSDMD, N‑terminal GSDMD (GSDMD‑N), and cleaved (c‑) caspase‑1 levels. MI increased IL‑1β and IL‑18 levels. These alterations were alleviated by IRF2 silencing. Furthermore, in hypoxia‑treated H9c2 cells, IRF2 silencing significantly decreased the elevated levels of IL‑1β and IL‑18 and pyroptosis‑associated proteins, including GSDMD, GSDMD‑N and c‑caspase1. Moreover, in hypoxia‑treated H9c2 cells, IRF2 directly bound to the GSDMD promoter to drive GSDMD transcription and promote pyroptosis and IRF2 expression may be regulated via the hypoxia inducible factor 1 signaling pathway. In conclusion, the present results demonstrated that IRF2 is a key regulator of MI by mediating pyroptosis, which triggers GSDMD activation.

NLRP3 Inflammasome Inhibitors in Cardiovascular Diseases

Virtually all types of cardiovascular diseases are associated with pathological activation of the innate immune system. The NACHT, leucine-rich repeat (LRR), and pyrin domain (PYD)-containing protein 3 (NLRP3) inflammasome is a protein complex that functions as a platform for rapid induction of the inflammatory response to infection or sterile injury. NLRP3 is an intracellular sensor that is sensitive to danger signals, such as ischemia and extracellular or intracellular alarmins during tissue injury. The NLRP3 inflammasome is regulated by the presence of damage-associated molecular patterns and initiates or amplifies inflammatory response through the production of interleukin-1β (IL-1β) and/or IL-18. NLRP3 activation regulates cell survival through the activity of caspase-1 and gasdermin-D. The development of NLRP3 inflammasome inhibitors has opened the possibility to targeting the deleterious effects of NLRP3. Here, we examine the scientific evidence supporting a role for NLRP3 and the effects of inhibitors in cardiovascular diseases.

Absence of NLRP3 Inflammasome in Hematopoietic Cells Reduces Adverse Remodeling After Experimental Myocardial Infarction

An inflammatory response is required for tissue healing after a myocardial infarction (MI), but the process must be balanced to prevent maladaptive remodeling. This study shows that improved survival and cardiac function following MI, in mice deficient for the NLRP3 inflammasome, can be recapitulated in wild-type mice receiving bone marrow from Nlrp3 ^-/- mice. This suggests that NLRP3 activation in hematopoietic cells infiltrating in the myocardium increases mortality and late ventricular remodeling. Our data should encourage performing clinical trials directly targeting NLRP3 inflammasome and their inflammatory cytokines (interleukin-1β and -18) in MI patients.

Glycogen synthase kinase-3β inhibition alleviates activation of the NLRP3 inflammasome in myocardial infarction

Inflammasome-promoted sterile inflammation following cardiac damage is critically implicated in heart dysfunction after myocardial infarction (MI). Glycogen synthase kinase-3 (GSK-3β) is a prominent mediator of the inflammatory response, and high GSK-3 activity is associated with various heart diseases. We investigated the regulatory mechanisms of GSK-3β in activation of the nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome in a rat model with successful induction of MI on days 2-28. An in vitro investigation was performed using newborn rat/human cardiomyocytes and fibroblast cultures under typical inflammasome stimulation and hypoxia treatment. GSK-3β inhibition markedly improved myocardial dysfunction and prevented remodeling, with parallel reduction in the parameters of NLRP3 inflammasome activation after MI. GSK-3β inhibition reduced NLRP3 inflammasome activation in cardiac fibroblasts, but not in cardiomyocytes. GSK-3β's interaction with activating signal cointegrator (ASC) as well as GSK-3β inhibition reduced ASC phosphorylation and oligomerization at the tissues and cellular levels. Taken together, these data show that GSK-3β directly mediates NLRP3 inflammasome activation, causing cardiac dysfunction in MI.

Targeting Inflammation After Myocardial Infarction

PURPOSE OF REVIEW

Inflammation plays a key role in clearing cellular debris and recovery after acute myocardial infarction (AMI). Dysregulation of or prolonged inflammation may result in adverse cardiac remodeling and major adverse clinical events (MACE). Several pre-clinical studies and moderate sized clinical trials have investigated the role of immunomodulation in improving clinical outcomes in patients with AMI.

RECENT FINDINGS

Clinical data from the Canakinumab Atherothrombosis Outcome (CANTOS) and Colchicine Cardiovascular Outcomes Trial (COLCOT) have provided encouraging results among patients with AMI. Several other clinical and pre-clinical trials have brought about the prospect of modulating inflammation at various junctures of the inflammatory cascade including inhibition of complement cascade, interleukins, and matrix metalloproteinases. In patients with AMI, modulation of residual inflammation via various inflammatory pathways and mediators may hold promise for further reducing MACE. Learning from current data and understanding the nuances of immunomodulation in AMI are key for future trials and before widespread dissemination of such therapies.

Targeting the NLRP3 Inflammasome in Severe COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a member of the genus Betacoronavirus within the family Coronaviridae. It is an enveloped single-stranded positive-sense RNA virus. Since December of 2019, a global expansion of the infection has occurred with widespread dissemination of coronavirus disease 2019 (COVID-19). COVID-19 often manifests as only mild cold-like symptomatology, but severe disease with complications occurs in 15% of cases. Respiratory failure occurs in severe disease that can be accompanied by a systemic inflammatory reaction characterized by inflammatory cytokine release. In severe cases, fatality is caused by the rapid development of severe lung injury characteristic of acute respiratory distress syndrome (ARDS). Although ARDS is a complication of SARS-CoV-2 infection, it is not viral replication or infection that causes tissue injury; rather, it is the result of dysregulated hyperinflammation in response to viral infection. This pathology is characterized by intense, rapid stimulation of the innate immune response that triggers activation of the Nod-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome pathway and release of its products including the proinflammatory cytokines IL-6 and IL-1β. Here we review the literature that describes the pathogenesis of severe COVID-19 and NLRP3 activation and describe an important role in targeting this pathway for the treatment of severe COVID-19.

NLRP3 Inflammasome in Acute Myocardial Infarction

Acute myocardial infarction (AMI) is associated with the induction of a sterile inflammatory response that leads to further injury. The NACHT, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome is a macromolecular structure responsible for the inflammatory response to injury or infection. NLRP3 can sense intracellular danger signals, such as ischemia and extracellular or intracellular alarmins during tissue injury. The NLRP3 inflammasome is primed and triggered by locally released damage-associated molecular patterns and amplifies the inflammatory response and cell death through caspase-1 activation. Here, we examine the scientific evidence supporting a role for NLRP3 in AMI and the available strategies to inhibit the effects of the inflammasome. Our focus is on the beneficial effects seen in experimental models of AMI in preclinical animal models and the initial results of clinical trials.

NLRP3 Inflammasome Signaling as a Link Between HIV-1 Infection and Atherosclerotic Cardiovascular Disease

36.9 million people worldwide are living with HIV-1. The disease remains incurable and HIV-infected patients have increased risk of atherosclerosis. Inflammation is a key driver of atherosclerosis, but no targeted molecular therapies have been developed to reduce cardiovascular risk in people with HIV-1 (PWH). While the mechanism is unknown, there are several important inflammatory signaling events that are implicated in the development of chronic inflammation in PWH and in the inflammatory changes that lead to atherosclerosis. Here we describe the pro-inflammatory state of HIV-1 infection that leads to increased risk of cardiovascular disease, the role of the NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasome in HIV-1 infection, the role of the NLRP3 inflammasome in cardiovascular disease (CVD), and outline a model whereby HIV-1 infection can lead to atherosclerotic disease through NLRP3 inflammasome activation. Our discussion highlights the literature supporting HIV-1 infection as a stimulator of the NLRP3 inflammasome as a driver of atherosclerosis.

Interleukin-1 and the Inflammasome as Therapeutic Targets in Cardiovascular Disease

The intracellular sensing protein termed NLRP3 (for NACHT, LRR, and PYD domains-containing protein 3) forms a macromolecular structure called the NLRP3 inflammasome. The NLRP3 inflammasome plays a major role in inflammation, particularly in the production of IL (interleukin)-1β. IL-1β is the most studied of the IL-1 family of cytokines, including 11 members, among which are IL-1α and IL-18. Here, we summarize preclinical and clinical findings supporting the key pathogenetic role of the NLRP3 inflammasome and IL-1 cytokines in the formation, progression, and complications of atherosclerosis, in ischemic (acute myocardial infarction), and nonischemic injury to the myocardium (myocarditis) and the progression to heart failure. We also review the clinically available IL-1 inhibitors, although not currently approved for cardiovascular indications, and discuss other IL-1 inhibitors, not currently approved, as well as oral NLRP3 inflammasome inhibitors currently in clinical development. Canakinumab, IL-1β antibody, prevented the recurrence of ischemic events in patients with prior acute myocardial infarction in a large phase III clinical trial, including 10 061 patients world-wide. Phase II clinical trials show promising data with anakinra, recombinant IL-1 receptor antagonist, in patients with ST-segment-elevation acute myocardial infarction or heart failure with reduced ejection fraction. Anakinra also improved outcomes in patients with pericarditis, and it is now considered standard of care as second-line treatment for patients with recurrent/refractory pericarditis. Rilonacept, a soluble IL-1 receptor chimeric fusion protein neutralizing IL-1α and IL-1β, has also shown promising results in a phase II study in recurrent/refractory pericarditis. In conclusion, there is overwhelming evidence linking the NLRP3 inflammasome and the IL-1 cytokines with the pathogenesis of cardiovascular diseases. The future will likely include targeted inhibitors to block the IL-1 isoforms, and possibly oral NLRP3 inflammasome inhibitors, across a wide spectrum of cardiovascular diseases.

Kanglexin, a novel anthraquinone compound, protects against myocardial ischemic injury in mice by suppressing NLRP3 and pyroptosis

Pyroptosis is a form of inflammatory cell death that could be driven by the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation following myocardial infarction (MI). Emerging evidence suggests the therapeutic potential for ameliorating MI-induced myocardial damages by targeting NLRP3 and pyroptosis. In this study, we investigated the myocardial protection effect of a novel anthraquinone compound (4,5-dihydroxy-7-methyl-9,10-anthraquinone-2-ethyl succinate) named Kanglexin (KLX) in vivo and in vitro. Male C57BL/6 mice were pre-treated either with KLX (20, 40 mg· kg^-1per day, intragastric gavage) or vehicle for 7 consecutive days prior to ligation of coronary artery to induce permanent MI. KLX administration dose-dependently reduced myocardial infarct size and lactate dehydrogenase release and improved cardiac function as compared to vehicle-treated mice 24 h after MI. We found that MI triggered NLRP3 inflammasome activation leading to conversion of interleukin-1β (IL-1β) and IL-18 into their active mature forms in the heart, which could expand the infarct size and drive cardiac dysfunction. We also showed that MI induced pyroptosis, as evidenced by increased DNA fragmentation, mitochondrial swelling, and cell membrane rupture, as well as increased levels of pyroptosis-related proteins, including gasdermin D, N-terminal GSDMD, and cleaved caspase-1. All these detrimental alterations were prevented by KLX. In hypoxia- or lipopolysaccharide (LPS)-treated neonatal mouse ventricular cardiomyocytes, we showed that KLX (10 μM) decreased the elevated levels of terminal deoxynucleotidyl transferase dUTP nick end labeling- and propidium iodide-positive cells, and pyroptosis-related proteins. We conclude that KLX prevents MI-induced cardiac damages and cardiac dysfunction at least partly through attenuating NLRP3 and subsequent cardiomyocyte pyroptosis, and it is worthy of more rigorous investigations for its potential for alleviating ischemic heart disease.

Dietary metabolism, the gut microbiome, and heart failure

Advances in our understanding of how the gut microbiota contributes to human health and diseases have expanded our insight into how microbial composition and function affect the human host. Heart failure is associated with splanchnic circulation congestion, leading to bowel wall oedema and impaired intestinal barrier function. This situation is thought to heighten the overall inflammatory state via increased bacterial translocation and the presence of bacterial products in the systemic blood circulation. Several metabolites produced by gut microorganisms from dietary metabolism have been linked to pathologies such as atherosclerosis, hypertension, heart failure, chronic kidney disease, obesity, and type 2 diabetes mellitus. These findings suggest that the gut microbiome functions like an endocrine organ by generating bioactive metabolites that can directly or indirectly affect host physiology. In this Review, we discuss several newly discovered gut microbial metabolic pathways, including the production of trimethylamine and trimethylamine N-oxide, short-chain fatty acids, and secondary bile acids, that seem to participate in the development and progression of cardiovascular diseases, including heart failure. We also discuss the gut microbiome as a novel therapeutic target for the treatment of cardiovascular disease, and potential strategies for targeting intestinal microbial processes.

Endoplasmic reticulum stress-induced iRhom2 up-regulation promotes macrophage-regulated cardiac inflammation and lipid deposition in high fat diet (HFD)-challenged mice: Intervention of fisetin and metformin

Endoplasmic reticulum stress (ERS) has been implicated in obesity-associated cardiac remodeling and dysfunction. Inactive rhomboid protein 2 (iRhom2), also known as Rhbdf2, is an inactive member of the rhomboid intramembrane proteinase family, playing an essential role in regulating inflammation. Nevertheless, the role of ERS-meditated iRhom2 pathway in metabolic stress-induced cardiomyopathy remains unknown. In the study, we showed that 4-PBA, as an essential ERS inhibitor, significantly alleviated high fat diet (HFD)-induced metabolic disorder and cardiac dysfunction in mice. Additionally, lipid deposition in heart tissues was prevented by 4-PBA in HFD-challenged mice. Moreover, 4-PBA blunted the expression of iRhom2, TACE, TNFR2 and phosphorylated NF-κB to prevent HFD-induced expression of inflammatory factors. Further, 4-PBA restrained HFD-triggered oxidative stress by promoting Nrf-2 signaling. Importantly, 4-PBA markedly suppressed cardiac ERS in HFD mice. The anti-inflammation, anti-ERS and anti-oxidant effects of 4-PBA were verified in palmitate (PAL)-incubated macrophages and cardiomyocytes. In addition, promoting ERS could obviously enhance iRhom2 signaling in vitro. Intriguingly, our data demonstrated that PAL-induced iRhom2 up-regulation apparently promoted macrophage to generate inflammatory factors that could promote cardiomyocyte inflammation and lipid accumulation. Finally, interventions by adding fisetin or metformin significantly abrogated metabolic stress-induced cardiomyopathy through the mechanisms mentioned above. In conclusion, this study provided a novel mechanism for metabolic stress-induced cardiomyopathy pathogenesis. Therapeutic strategy to restrain ROS/ERS/iRhom2 signaling pathway could be developed to prevent myocardial inflammation and lipid deposition, consequently alleviating obesity-induced cardiomyopathy.

Potential Therapeutic Value of Interleukin 1b-targeted Strategies in Atherosclerotic Cardiovascular Disease

Clinical trials have unequivocally shown that cholesterol-lowering drugs decrease the risk of atherosclerotic cardiovascular disease in an exceptionally wide range of individuals. Yet, even when treated optimally according to current standards, many individuals still experience life-threatening ischemic events. Emerging experimental and clinical evidence strongly suggests that persistent inflammation is a major driver of this residual risk, which has opened the door to the application of anti-inflammatory drugs for cardiovascular disease prevention. Here, we review our current knowledge of the biology of interleukin-1β, a key regulator of inflammation in atherosclerotic plaque and the target of the first clinical trial to demonstrate that an anti-inflammatory drug can effectively reduce cardiovascular risk. We discuss the challenges faced by interleukin-1β inhibitors and other anti-inflammatory compounds in their translation to the clinical scenario, and identify other potential targets within this signaling pathway that hold promise in the cardiovascular setting.

Inflammasome, pyroptosis, and cytokines in myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury induces a sterile inflammatory response, leading to further injury that contributes to the final infarct size. Locally released danger-associated molecular patterns lead to priming and triggering of the NOD-like receptor protein 3 inflammasome and amplification of the inflammatory response and cell death by activation of caspase-1. We review strategies inhibiting priming, triggering, or caspase-1 activity or blockade of the inflammasome-related cytokines interleukin-1β and interleukin-18, focusing on the beneficial effects in experimental models of acute myocardial infarction in animals and the initial results of clinical translational research trials.

Role of complement C5a and histones in septic cardiomyopathy

Polymicrobial sepsis (after cecal ligation and puncture, CLP) causes robust complement activation with release of C5a. Many adverse events develop thereafter and will be discussed in this review article. Activation of complement system results in generation of C5a which interacts with its receptors (C5aR1, C5aR2). This leads to a series of harmful events, some of which are connected to the cardiomyopathy of sepsis, resulting in defective action potentials in cardiomyocytes (CMs), activation of the NLRP3 inflammasome in CMs and the appearance of extracellular histones, likely arising from activated neutrophils which form neutrophil extracellular traps (NETs). These events are associated with activation of mitogen-activated protein kinases (MAPKs) in CMs. The ensuing release of histones results in defective action potentials in CMs and reduced levels of [Ca²⁺]i-regulatory enzymes including sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA2) and Na⁺/Ca²⁺ exchanger (NCX) as well as Na⁺/K⁺-ATPase in CMs. There is also evidence that CLP causes release of IL-1β via activation of the NLRP3 inflammasome in CMs of septic hearts or in CMs incubated in vitro with C5a. Many of these events occur after in vivo or in vitro contact of CMs with histones. Together, these data emphasize the role of complement (C5a) and C5a receptors (C5aR1, C5aR2), as well as extracellular histones in events that lead to cardiac dysfunction of sepsis (septic cardiomyopathy).

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.

The Inflammasomes in Cardiovascular Disease

Cardiovascular disease (CVD) is the number one cause of death worldwide. The pathogenesis of various disease entities that comprise the area of CVD is complex and multifactorial. Inflammation serves a central role in these complex aetiologies. The inflammasomes are intracellular protein complexes activated by danger-associated molecular patterns (DAMPs) present in CVD such as atherosclerosis and myocardial infarction (MI). After a two-step process of priming and activation, inflammasomes are responsible for the formation of pro-inflammatory cytokines interleukin-1β and interleukin-18, inducing a signal transduction cascade resulting in a strong immune response that culminates in disease progression. In the past few years, increased interest has been raised regarding the inflammasomes in CVD. Inflammasome activation is thought to be involved in the pathogenesis of various disease entities such as atherosclerosis, MI and heart failure (HF). Interference with inflammasome-mediated signalling could reduce inflammation and attenuate the severity of disease. In this chapter we provide an overview of the current literature available on the role of inflammasome inhibition as a therapeutic intervention and the possible clinical implications for CVD.

Cellular Therapeutics for Heart Failure: Focus on Mesenchymal Stem Cells

Resulting from a various etiologies, the most notable remains ischemia; heart failure (HF) manifests as the common end pathway of many cardiovascular processes and remains among the top causes for hospitalization and a major cause of morbidity and mortality worldwide. Current pharmacologic treatment for HF utilizes pharmacologic agents to control symptoms and slow further deterioration; however, on a cellular level, in a patient with progressive disease, fibrosis and cardiac remodeling can continue leading to end-stage heart failure. Cellular therapeutics have risen as the new hope for an improvement in the treatment of HF. Mesenchymal stem cells (MSCs) have gained popularity given their propensity of promoting endogenous cellular repair of a myriad of disease processes via paracrine signaling through expression of various cytokines, chemokines, and adhesion molecules resulting in activation of signal transduction pathways. While the exact mechanism remains to be completely elucidated, this remains the primary mechanism identified to date. Recently, MSCs have been incorporated as the central focus in clinical trials investigating the role how MSCs can play in the treatment of HF. In this review, we focus on the characteristics of MSCs that give them a distinct edge as cellular therapeutics and present results of clinical trials investigating MSCs in the setting of ischemic HF.

Role of NLRP3 inflammasome in the pathogenesis of cardiovascular diseases

NLRP3 inflammasome is a key multiprotein signaling platform that tightly controls inflammatory responses and coordinates antimicrobial host defenses by activating caspase-1 for the subsequent maturation of pro-inflammatory cytokines, IL-1β and IL-18, and induces pyroptosis. The assembly and activation of NLRP3 inflammasome are linked to the pathogenesis of several cardiovascular disease risk factors, such as hypertension and diabetes, and their major consequences-myocardial remodeling. The study of the NLRP3 inflammasome in these cardiovascular disease states may uncover important triggers and endogenous modulators of the disease, and lead to new treatment strategies. This review outlines current insights into NLRP3 inflammasome research associated with cardiovascular diseases and discusses the questions that remain in this field.

Reduction of Myocardial Ischemia-Reperfusion Injury by Inhibiting Interleukin-1 Alpha

BACKGROUND

Interleukin-1α (IL-1α) released by dying cells is an alarmin that activates the innate immunity. We hypothesized that after myocardial ischemia-reperfusion (I/R) injury, IL-1α amplifies the myocardial damage by activating the inflammasome and caspase-1.

METHODS

Adult male CD1 mice were used. The left anterior descending coronary artery was ligated for 30 minutes, after 24 hours of reperfusion. An IL-1α blocking antibody (15 μg/kg intraperitoneally) or matching vehicle was given after reperfusion. A subgroup of mice underwent sham surgery. We assessed the effects of IL-1α blockade on caspase-1 activity, infarct size, cardiac troponin I serum levels, and left ventricular fractional shortening, 24 hours after I/R.

RESULTS

I/R led to inflammasome formation, and IL-1α blockade significantly reduced inflammasome formation, reflected by a >50% reduction in caspase-1 activity versus vehicle (P = 0.03). IL-1α blockade also reduced the infarct size (-52% infarct expressed as percentage of area at risk, and -79% for cardiac troponin I serum levels, P < 0.001 vs. vehicle) and preserved the left ventricular fractional shortening (31 ± 3% vs. 25 ± 2%, P < 0.001 vs. vehicle).

CONCLUSION

IL-1α blockade after I/R reduces the inflammasome activation, decreases the infarct size, and preserves the left ventricular function. IL-1α blockade may therefore represent a novel therapeutic strategy to reduce I/R injury.

The IL-1β Antibody Gevokizumab Limits Cardiac Remodeling and Coronary Dysfunction in Rats With Heart Failure

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Immediate IL-1β antibody gevokizumab administration reduces ischemia/reperfusion related infarct size.

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Immediate and late IL-1β antibody gevokizumab administration improves heart failure related left ventricular remodeling.

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IL-1β antibody gevokizumab improves heart failure related coronary dysfunction.

This study reports preclinical data showing that the interleukin (IL)-1β modulation is a new promising target in the pathophysiological context of heart failure. Indeed, in nondiabetic Wistar and diabetic Goto-Kakizaki rats with chronic heart failure induced by myocardial infarction, administration of the IL-1β antibody gevokizumab improves ‘surrogate’ markers of survival (i.e., left ventricular remodeling, hemodynamics, and function as well as coronary function). However, whether IL-1β modulation per se or in combination with standard treatments of heart failure improves long-term outcome in human heart failure remains to be determined.

Failure to Launch: Targeting Inflammation in Acute Coronary Syndromes

The importance of inflammation and inflammatory pathways in atherosclerotic disease and acute coronary syndromes (ACS) is well established. The success of statin therapy rests not only on potently reducing levels of low-density lipoprotein cholesterol, but also on the many beneficial, pleiotropic effects statin therapy has on various inflammatory mechanisms in atherosclerotic disease, from reducing endothelial dysfunction to attenuating levels of serum C-reactive protein. Due to the growing awareness of the importance of inflammation in ACS, investigators have attempted to develop novel therapies against known markers of inflammation for several decades. Targeted pathways have ranged from inhibiting C5 cleavage with a high-affinity monoclonal antibody against C5 to inhibiting the activation of the p38 mitogen-activated protein kinase signaling cascades. In each of these instances, despite promising early preclinical and mechanistic studies and phase 2 trials suggesting a potential benefit in reducing post-MI complications or restenosis, these novel therapies have failed to show benefits during large, phase 3 clinical outcomes trials. This review discusses several examples of novel anti-inflammatory therapies that failed to show significant improvement on clinical outcomes when tested in large, randomized trials and highlights potential explanations for why targeted therapies against known markers of inflammation in ACS have failed to launch.

Pediatric and adult dilated cardiomyopathy represent distinct pathological entities

Pediatric dilated cardiomyopathy (DCM) is the most common indication for heart transplantation in children. Despite similar genetic etiologies, medications routinely used in adult heart failure patients do not improve outcomes in the pediatric population. The mechanistic basis for these observations is unknown. We hypothesized that pediatric and adult DCM comprise distinct pathological entities, in that children do not undergo adverse remodeling, the target of adult heart failure therapies. To test this hypothesis, we examined LV specimens obtained from pediatric and adult donor controls and DCM patients. Consistent with the established pathophysiology of adult heart failure, adults with DCM displayed marked cardiomyocyte hypertrophy and myocardial fibrosis compared with donor controls. In contrast, pediatric DCM specimens demonstrated minimal cardiomyocyte hypertrophy and myocardial fibrosis compared with both age-matched controls and adults with DCM. Strikingly, RNA sequencing uncovered divergent gene expression profiles in pediatric and adult patients, including enrichment of transcripts associated with adverse remodeling and innate immune activation in adult DCM specimens. Collectively, these findings reveal that pediatric and adult DCM represent distinct pathological entities, provide a mechanistic basis to explain why children fail to respond to adult heart failure therapies, and suggest the need to develop new approaches for pediatric DCM.

IL-1β Inhibition in Cardiovascular Complications Associated to Diabetes Mellitus

Diabetes mellitus (DM) is a chronic disease that affects nowadays millions of people worldwide. In adults, type 2 diabetes mellitus (T2DM) accounts for the majority of all diagnosed cases of diabetes. The course of the T2DM is characterized by insulin resistance and a progressive loss of β-cell mass. DM is associated with a number of related complications, among which cardiovascular complications and atherosclerosis are the main cause of morbidity and mortality in patients suffering from the disease. DM is acknowledged as a low-grade chronic inflammatory state characterized by the over-secretion of pro-inflammatory cytokines, including interleukin (IL)-1β, which reinforce inflammatory signals thus contributing to the development of complications. In this context, the pharmacological approaches to treat diabetes should not only correct hyperglycaemia, but also attenuate inflammation and prevent the development of metabolic and cardiovascular complications. Over the last years, novel biological drugs have been developed to antagonize the pathophysiological actions of IL-1β. The drugs currently used in clinical practice are anakinra, a recombinant form of the naturally occurring IL-1 receptor antagonist, the soluble decoy receptor rilonacept and the monoclonal antibodies canakinumab and gevokizumab. This review will summarize the main experimental and clinical findings obtained with pharmacological IL-1β inhibitors in the context of the cardiovascular complications of DM, and discuss the perspectives of IL-1β inhibitors as novel therapeutic tools for treating these patients.

Antiarrhythmic effects of interleukin 1 inhibition after myocardial infarction

BACKGROUND

Interleukin 1β (IL-1β) is a key regulator of the inflammatory response after myocardial infarction (MI) by modulating immune cell recruitment, cytokine production, and extracellular matrix turnover. Elevated levels of IL-1β are associated with adverse remodeling, and inhibition of IL-1 signaling after MI results in improved contractile function.

OBJECTIVE

The goal of this study was to determine whether IL-1 signaling also contributes to post-MI arrhythmogenesis.

METHODS

MI was created in 2 murine models of elevated inflammation: atherosclerotic on the Western diet or wild-type with a subseptic dose of lipopolysaccharide. The role of IL-1β was assessed with the IL-1 receptor antagonist anakinra (10 mg/(kg·d), starting 24 hours post-MI).

RESULTS

In vivo and ex vivo molecular imaging showed reduced myocardial inflammation after a 4-day course of anakinra treatment, despite no change in infarct size. At day 5 post-MI, high-speed optical mapping of transmembrane potential and intracellular Ca²⁺ in isolated hearts revealed that IL-1β inhibition improved conduction velocity, reduced action potential duration dispersion, improved intracellular Ca²⁺ handling, decreased transmembrane potential and Ca²⁺ alternans magnitude, and reduced spontaneous and inducible ventricular arrhythmias. These functional improvements were linked to increased expression of connexin 43 and sarcoplasmic reticulum Ca²⁺-ATPase.

CONCLUSION

This study revealed a novel mechanism for IL-1β in contributing to defective excitation-contraction coupling and arrhythmogenesis in the post-MI heart. Our results suggest that inhibition of IL-1 signaling post-MI may represent a novel antiarrhythmic therapy.

L5-LDL from ST-elevation myocardial infarction patients induces IL-1β production via LOX-1 and NLRP3 inflammasome activation in macrophages

L5-LDL, the most electronegative LDL associated with major cardiovascular risks, significantly rises in patients with ST-segment elevation myocardial infarction (STEMI). The inflammatory nature of atherosclerotic vascular diseases has prompted us to investigate whether L5-LDL induces the production of inflammatory cytokines, especially vascular ischemia-related interleukin (IL)-1β, in the pathogenesis of STEMI. Clinical data showed that plasma levels of L5-LDL and IL-1β were higher in the STEMI patients than in the controls (P < 0.05). In THP-1-derived human macrophages, L5-LDL significantly increased the levels of both IL-1β and cleaved caspase-1, indicating the activation of NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasomes by L5-LDL. Knockdown of NLRP3 and its adaptor protein apoptosis-associated speck-like protein containing a CARD (ASC) resulted in decreased L5-LDL-induced IL-1β. Furthermore, knock down of the lectin-type oxidized LDL receptor (LOX-1) in THP-1 cells attenuated L5-LDL-induced activation of NF-κB and caspase-1, leading to subsequent inhibition of IL-1β in macrophages. Furthermore, blockade LOX-1 with neutralizing antibody also inhibited L5-LDL-induced IL-1β in human peripheral blood mononuclear cell-derived macrophages. In conclusion, L5-LDL induces IL-1β production in macrophages by activation of NF-κB and caspase-1 through the LOX-1-dependent pathway. This study represents the evidence linking L5-LDL and the inflammatory cytokine IL-1β in STEMI, and identifies L5-LDL as a novel therapeutic target in acute myocardial infarction.

NEW & NOTEWORTHY

This study represents the evidence linking L5-LDL and the inflammatory cytokine IL-1β in ST-segment elevation myocardial infarction (STEMI). We elucidate the molecular mechanism underlying L5-LDL-induced production of IL-1β in macrophages. The results showed that L5-LDL induced activation of caspase-1 and NF-κB through the lectin-type oxidized LDL receptor (LOX-1)-dependent pathway, leading to the production of IL-1β.

Complement-induced activation of the cardiac NLRP3 inflammasome in sepsis

Cardiac dysfunction develops during sepsis in humans and rodents. In the model of polymicrobial sepsis induced by cecal ligation and puncture (CLP), we investigated the role of the NLRP3 inflammasome in the heart. Mouse heart homogenates from sham-procedure mice contained high mRNA levels of NLRP3 and IL-1β. Using the inflammasome protocol, exposure of cardiomyocytes (CMs) to LPS followed by ATP or nigericin caused release of mature IL-1β. Immunostaining of left ventricular frozen sections before and 8 h after CLP revealed the presence of NLRP3 and IL-1β proteins in CMs. CLP caused substantial increases in mRNAs for IL-1β and NLRP3 in CMs which are reduced in the absence of either C5aR1 or C5aR2. After CLP, NLRP3^-/- mice showed reduced plasma levels of IL-1β and IL-6. In vitro exposure of wild-type CMs to recombinant C5a (rC5a) caused elevations in both cytosolic and nuclear/mitochondrial reactive oxygen species (ROS), which were C5a-receptor dependent. Use of a selective NOX2 inhibitor prevented increased cytosolic and nuclear/mitochondrial ROS levels and release of IL-1β. Finally, NLRP3^-/- mice had reduced defects in echo/Doppler parameters in heart after CLP. These studies establish that the NLRP3 inflammasome contributes to the cardiomyopathy of polymicrobial sepsis.-Kalbitz, M., Fattahi, F., Grailer, J. J., Jajou, L., Malan, E. A., Zetoune, F. S., Huber-Lang, M., Russell, M. W., Ward, P. A. Complement-induced activation of the cardiac NLRP3 inflammasome in sepsis.

Pharmacology of heart failure: From basic science to novel therapies

Chronic heart failure is one of the leading causes for hospitalization in the United States and Europe, and is accompanied by high mortality. Current pharmacological therapy of chronic heart failure with reduced ejection fraction is largely based on compounds that inhibit the detrimental action of the adrenergic and the renin-angiotensin-aldosterone systems on the heart. More than one decade after spironolactone, two novel therapeutic principles have been added to the very recently released guidelines on heart failure therapy: the HCN-channel inhibitor ivabradine and the combined angiotensin and neprilysin inhibitor valsartan/sacubitril. New compounds that are in phase II or III clinical evaluation include novel non-steroidal mineralocorticoid receptor antagonists, guanylate cyclase activators or myosine activators. A variety of novel candidate targets have been identified and the availability of gene transfer has just begun to accelerate translation from basic science to clinical application. This review provides an overview of current pharmacology and pharmacotherapy in chronic heart failure at three stages: the updated clinical guidelines of the American Heart Association and the European Society of Cardiology, new drugs which are in clinical development, and finally innovative drug targets and their mechanisms in heart failure which are emerging from preclinical studies will be discussed.

Targeting the Innate Immune Response to Improve Cardiac Graft Recovery after Heart Transplantation: Implications for the Donation after Cardiac Death

Heart transplantation (HTx) is the ultimate treatment for end-stage heart failure. The number of patients on waiting lists for heart transplants, however, is much higher than the number of available organs. The shortage of donor hearts is a serious concern since the population affected by heart failure is constantly increasing. Furthermore, the long-term success of HTx poses some challenges despite the improvement in the management of the short-term complications and in the methods to limit graft rejection. Myocardial injury occurs during transplantation. Injury initiated in the donor as result of brain or cardiac death is exacerbated by organ procurement and storage, and is ultimately amplified by reperfusion injury at the time of transplantation. The innate immune system is a mechanism of first-line defense against pathogens and cell injury. Innate immunity is activated during myocardial injury and produces deleterious effects on the heart structure and function. Here, we briefly discuss the role of the innate immunity in the initiation of myocardial injury, with particular focus on the Toll-like receptors and inflammasome, and how to potentially expand the donor population by targeting the innate immune response.

Can heart function lost to disease be regenerated by therapeutic targeting of cardiac scar tissue?

Myocardial infarction results in scar tissue that cannot actively contribute to heart mechanical function and frequently causes lethal arrhythmias. The healing response after infarction involves inflammation, biochemical signaling, changes in cellular phenotype, activity, and organization, and alterations in electrical conduction due to variations in cell and tissue geometry and alterations in protein expression, organization, and function - particularly in membrane channels. The intensive research focus on regeneration of myocardial tissues has, as of yet, only met with modest success, with no near-term prospect of improving standard-of-care for patients with heart disease. An alternative concept for novel therapeutic approach is the rejuvenation of cardiac electrical and mechanical properties through the modification of scar tissue. Several peptide therapeutics, locally applied genetic therapies, or delivery of genetically modified cells have shown promise in improving the characteristics of the fibrous scar and post-myocardial infarction prognosis in experimental models. This review highlights several factors that contribute to arrhythmogenesis in scar formation and how these might be targeted to regenerate some of the electrical and mechanical function of the post-MI scar.