The role of interleukin-1 in the failing heart

The interplay between cytokines, inflammation, and antioxidants: mechanistic insights and therapeutic potentials of various antioxidants and anti-cytokine compounds

Cytokines regulate immune responses essential for maintaining immune homeostasis, as deregulated cytokine signaling can lead to detrimental outcomes, including inflammatory disorders. The antioxidants emerge as promising therapeutic agents because they mitigate oxidative stress and modulate inflammatory pathways. Antioxidants can potentially ameliorate inflammation-related disorders by counteracting excessive cytokine-mediated inflammatory responses. A comprehensive understanding of cytokine-mediated inflammatory pathways and the interplay with antioxidants is paramount for developing natural therapeutic agents targeting inflammation-related disorders and helping to improve clinical outcomes and enhance the quality of life for patients. Among these antioxidants, curcumin, vitamin C, vitamin D, propolis, allicin, and cinnamaldehyde have garnered attention for their anti-inflammatory properties and potential therapeutic benefits. This review highlights the interrelationship between cytokines-mediated disorders in various diseases and therapeutic approaches involving antioxidants.

Interaction between cardiac resynchronization therapy and cytokines in heart failure patients

Congestive heart failure (CHF) is a complex multistage syndrome that has a great financial burden on human societies. It was known that the damaged myocardium sends a signal to stimulate the immune system and proliferation of leukocytes. In continuous, cytokine storm can be initiated and causes the probability of CHF. Persistent inflammation by increasing the levels of pro-inflammatory cytokines, plays an important role in the pathogenesis of CHF and causes remodeling, which is a progressive processs. Although treatment by drugs can reduce mortality and partially control the symptoms of heart failure patients, but complications and mortality are still high. Therefore, other treatment options such as Cardiac Resynchronization Therapy (CRT) are necessary. Today, it is known that CRT can be an effective treatment for many patients with heart failure. CRT is novel, non-pharmacological, and device-based therapy that would be beneficial to know more about its performance in the management of heart failure. In this study, we have reviewed the immunological processes involved in heart failure and the effect of CRT in controlling of the cytokine storm.

Selective Inhibition of NLRP3 Inflammasome Reverses Pressure Overload-Induced Pathological Cardiac Remodeling by Attenuating Hypertrophy, Fibrosis, and Inflammation

Activation of the NLRP3 inflammasome promotes pathological cardiac remodeling induced by pressure overload. However, the therapeutic effects of NLRP3 inhibition after cardiac remodeling remain unknown. The present study aimed to investigate whether the selective NLRP3 inhibitor, MCC950, could reverse transverse aortic constriction (TAC)-induced cardiac remodeling. Mice were divided into four groups based on the treatment given: sham, sham + MCC950, TAC, and TAC + MCC950. MCC950 (10 mg/kg, intraperitoneal injection, once per day) was administered from two weeks after TAC or sham surgery for four weeks. Echocardiography, histological analysis, RT-PCR, and Western blotting were performed to explore the function of MCC950 after TAC. We found that MCC950 reversed cardiac dysfunction after TAC. MCC950 attenuated cardiac hypertrophy by down-regulating calcineurin expression and inhibiting MAPK activation. Further, it also alleviated cardiac fibrosis post-TAC by inhibiting the TGF-β/Smad4 pathway, and reduced cardiac inflammation and macrophage infiltration post-TAC, including both M1 and M2 macrophages. Taken together, MCC950 can attenuate cardiac remodeling due to pressure overload by inhibiting hypertrophy, fibrosis, and inflammation. Our study provides a basis for the clinical application of NLRP3 inhibitors in the treatment of non-ischemic heart failure.

Matrix metalloproteinase-9 as a messenger in the cross talk between obstructive sleep apnea and comorbid systemic hypertension, cardiac remodeling, and ischemic stroke: a literature review

STUDY OBJECTIVES

OSA is a common sleep disorder. There is a strong link between sleep-related breathing disorders and cardiovascular and cerebrovascular diseases. Matrix metalloproteinase-9 (MMP-9) is a biological marker for extracellular matrix degradation, which plays a significant role in systemic hypertension, myocardial infarction and postmyocardial infarction heart failure, and ischemic stroke. This article reviews MMP-9 as an inflammatory mediator and a potential messenger between OSA and OSA-induced comorbidities.

METHODS

We reviewed the MEDLINE database (PubMed) for publications on MMP-9, OSA, and cardiovascular disease, identifying 1,592 studies and including and reviewing 50 articles for this work.

RESULTS

There is strong evidence that MMP-9 and tissue inhibitor of metalloproteinase-1 levels are elevated in patients with OSA (mainly MMP-9), systemic hypertension, myocardial infarction, and postmyocardial infarction heart failure. Our study showed variable results that could be related to the sample size or to laboratory methodology.

CONCLUSIONS

MMP-9 and its endogenous inhibitor, tissue inhibitor of metalloproteinase-1, are a common denominator in OSA, systemic hypertension, myocardial infarction, and heart failure. This characterization makes MMP-9 a target for developing novel selective inhibitors that can serve as adjuvant therapy in patients with OSA, which may ameliorate the cardiovascular and cerebrovascular mortality associated with OSA.

Cardiac Fibroblasts and Myocardial Regeneration

The billions of cardiomyocytes lost to acute myocardial infarction (MI) cannot be replaced by the limited regenerative capacity of adult mammalian hearts, and despite decades of research, there are still no clinically effective therapies for remuscularizing and restoring damaged myocardial tissue. Although the majority of the cardiac mass is composed of cardiomyocytes, cardiac fibroblasts (CFs) are one type of most numerous cells in the heart and the primary drivers of fibrosis, which prevents ventricular rupture immediately after MI but the fibrotic scar expansion and LV dilatation can eventually lead to heart failure. However, embryonic CFs produce cytokines that can activate proliferation in cultured cardiomyocytes, and the structural proteins produced by CFs may regulate cardiomyocyte cell-cycle activity by modulating the stiffness of the extracellular matrix (ECM). CFs can also be used to generate induced-pluripotent stem cells and induced cardiac progenitor cells, both of which can differentiate into cardiomyocytes and vascular cells, but cardiomyocytes appear to be more readily differentiated from iPSCs that have been reprogrammed from CFs than from other cell types. Furthermore, the results from recent studies suggest that cultured CFs, as well as the CFs present in infarcted hearts, can be reprogrammed directly into cardiomyocytes. This finding is very exciting as should we be able to successfully increase the efficiency of this reprogramming, we could remuscularize the injured ventricle and restore the LV function without need the transplantation of cells or cell products. This review summarizes the role of CFs in the innate response to MI and how their phenotypic plasticity and involvement in ECM production might be manipulated to improve cardiac performance in injured hearts.

In vitro and In silico Models to Study SARS-CoV-2 Infection: Integrating Experimental and Computational Tools to Mimic "COVID-19 Cardiomyocyte"

The rapid dissemination of SARS-CoV-2 has made COVID-19 a tremendous social, economic, and health burden. Despite the efforts to understand the virus and treat the disease, many questions remain unanswered about COVID-19 mechanisms of infection and progression. Severe Acute Respiratory Syndrome (SARS) infection can affect several organs in the body including the heart, which can result in thromboembolism, myocardial injury, acute coronary syndromes, and arrhythmias. Numerous cardiac adverse events, from cardiomyocyte death to secondary effects caused by exaggerated immunological response against the virus, have been clinically reported. In addition to the disease itself, repurposing of treatments by using "off label" drugs can also contribute to cardiotoxicity. Over the past several decades, animal models and more recently, stem cell-derived cardiomyocytes have been proposed for studying diseases and testing treatments in vitro. In addition, mechanistic in silico models have been widely used for disease and drug studies. In these models, several characteristics such as gender, electrolyte imbalance, and comorbidities can be implemented to study pathophysiology of cardiac diseases and to predict cardiotoxicity of drug treatments. In this Mini Review, we (1) present the state of the art of in vitro and in silico cardiomyocyte modeling currently in use to study COVID-19, (2) review in vitro and in silico models that can be adopted to mimic the effects of SARS-CoV-2 infection on cardiac function, and (3) provide a perspective on how to combine some of these models to mimic "COVID-19 cardiomyocytes environment.".

BML-111 treatment prevents cardiac apoptosis and oxidative stress in a mouse model of autoimmune myocarditis

Myocarditis is an inflammation of the myocardium that can progress to a more severe phenotype of dilated cardiomyopathy (DCM). Three main harmful factors determine this progression: inflammation, cell death, and oxidative stress. Lipoxins and their derivatives are endogenous proresolving mediators that induce the resolution of the inflammatory process. This study aims to determine whether these mediators play a protective role in a murine model of experimental autoimmune myocarditis (EAM) by treating with the lipoxin A₄ analog BML-111. We observed that EAM mice presented extensive infiltration areas that correlated with higher levels of inflammatory and cardiac damage markers. Both parameters were significantly reduced in BML-treated EAM mice. Consistently, cardiac dysfunction, hypertrophy, and emerging fibrosis detected in EAM mice was prevented by BML-111 treatment. At the molecular level, we demonstrated that treatment with BML-111 hampered apoptosis and oxidative stress induction by EAM. Moreover, both in vivo and in vitro studies revealed that these beneficial effects were mediated by activation of Nrf2 pathway through CaMKK2-AMPKα kinase pathway. Altogether, our data indicate that treatment with the lipoxin derivative BML-111 effectively alleviates EAM outcome and prevents cardiac dysfunction, thus, underscoring the therapeutic potential of lipoxins and their derivatives to treat myocarditis and other inflammatory cardiovascular diseases.

Role of cytokines and inflammation in heart function during health and disease

By virtue of their actions on NF-κB, an inflammatory nuclear transcription factor, various cytokines have been documented to play important regulatory roles in determining cardiac function under both physiological and pathophysiological conditions. Several cytokines including TNF-α, TGF-β, and different interleukins such as IL-1 IL-4, IL-6, IL-8, and IL-18 are involved in the development of various inflammatory cardiac pathologies, namely ischemic heart disease, myocardial infarction, heart failure, and cardiomyopathies. In ischemia-related pathologies, most of the cytokines are released into the circulation and serve as biological markers of inflammation. Furthermore, there is an evidence of their direct role in the pathogenesis of ischemic injury, suggesting cytokines as potential targets for the development of some anti-ischemic therapies. On the other hand, certain cytokines such as IL-2, IL-4, IL-6, IL-8, and IL-10 are involved in the post-ischemic tissue repair and thus are considered to exert beneficial effects on cardiac function. Conflicting reports regarding the role of some cytokines in inducing cardiac dysfunction in heart failure and different types of cardiomyopathies seem to be due to differences in the nature, duration, and degree of heart disease as well as the concentrations of some cytokines in the circulation. In spite of extensive research work in this field of investigation, no satisfactory anti-cytokine therapy for improving cardiac function in any type of heart disease is available in the literature.

IFN-β Plays Both Pro- and Anti-inflammatory Roles in the Rat Cardiac Fibroblast Through Differential STAT Protein Activation

Cardiac fibroblasts (CFs) contribute to theinflammatory response to tissue damage, secreting both pro- and anti-inflammatory cytokines and chemokines. Interferon beta (IFN-β) induces the phosphorylation of signal transducer and activator of transcription (STAT) proteins through the activation of its own receptor, modulating the secretion of cytokines and chemokines which regulate inflammation. However, the role of IFN-β and STAT proteins in modulating the inflammatory response of CF remains unknown. CF were isolated from adult male rats and subsequently stimulated with IFN-β to evaluate the participation of STAT proteins in secreting chemokines, cytokines, cell adhesion proteins expression and in their capacity to recruit neutrophils. In addition, in CF in which the TRL4 receptor was pre-activated, the effect of INF-β on the aforementioned responses was also evaluated. Cardiac fibroblasts stimulation with IFN-β showed an increase in STAT1, STAT2, and STAT3 phosphorylation. IFN-β stimulation through STAT1 activation increased proinflammatory chemokines MCP-1 and IP-10 secretion, whereas IFN-β induced activation of STAT3 increased cytokine secretion of anti-inflammatory IL-10. Moreover, in TLR4-activated CF, IFN-β through STAT2 and/or STAT3, produced an anti-inflammatory effect, reducing pro-IL-1β, TNF-α, IL-6, MCP-1, and IP-10 secretion; and decreasing neutrophil recruitment by decreasing ICAM-1 and VCAM-1 expression. Altogether, our results indicate that IFN-β exerts both pro-inflammatory and anti-inflammatory effects in non-stimulated CF, through differential activation of STAT proteins. When CF were previously treated with an inflammatory agent such as TLR-4 activation, IFN-β effects were predominantly anti-inflammatory.

Development of the Myocardial Interstitium

The space between cardiac myocytes is commonly referred-to as the cardiac interstitium (CI). The CI is a unique, complex and dynamic microenvironment in which multiple cell types, extracellular matrix molecules, and instructive signals interact to crucially support heart homeostasis and promote cardiac responses to normal and pathologic stimuli. Despite the biomedical and clinical relevance of the CI, its detailed cellular structure remains to be elucidated. In this review, we will dissect the organization of the cardiac interstitium by following its changing cellular and molecular composition from embryonic developmental stages to adulthood, providing a systematic analysis of the biological components of the CI. The main goal of this review is to contribute to our understanding of the CI roles in health and disease. Anat Rec, 302:58-68, 2019. © 2018 Wiley Periodicals, Inc.

Intermediate filaments in cardiomyopathy

Intermediate filament (IF) proteins are critical regulators in health and disease. The discovery of hundreds of mutations in IF genes and posttranslational modifications has been linked to a plethora of human diseases, including, among others, cardiomyopathies, muscular dystrophies, progeria, blistering diseases of the epidermis, and neurodegenerative diseases. The major IF proteins that have been linked to cardiomyopathies and heart failure are the muscle-specific cytoskeletal IF protein desmin and the nuclear IF protein lamin, as a subgroup of the known desminopathies and laminopathies, respectively. The studies so far, both with healthy and diseased heart, have demonstrated the importance of these IF protein networks in intracellular and intercellular integration of structure and function, mechanotransduction and gene activation, cardiomyocyte differentiation and survival, mitochondrial homeostasis, and regulation of metabolism. The high coordination of all these processes is obviously of great importance for the maintenance of proper, life-lasting, and continuous contraction of this highly organized cardiac striated muscle and consequently a healthy heart. In this review, we will cover most known information on the role of IFs in the above processes and how their deficiency or disruption leads to cardiomyopathy and heart failure.

Interleukin-1 Blockade in Acute Decompensated Heart Failure: A Randomized, Double-Blinded, Placebo-Controlled Pilot Study

BACKGROUND

Heart failure is an inflammatory disease. Patients with acute decompensated heart failure (ADHF) exhibit significant inflammatory activity on admission. We hypothesized that Interleukin-1 blockade, with anakinra (Kineret, Swedish Orphan Biovitrum), would quench the acute inflammatory response in patients with ADHF.

METHODS

We randomized 30 patients with ADHF, reduced left ventricular ejection fraction (<40%), and elevated C reactive protein (CRP) levels (≥5 mg/L) to either anakinra 100 mg twice daily for 3 days followed by once daily for 11 days or matching placebo, in a 1:1 double blinded fashion. We measured daily CRP plasma levels using a high-sensitivity assay during hospitalization and then again at 14 days and evaluated the area-under-the-curve and interval changes (delta).

RESULTS

Treatment with anakinra was well tolerated. At 72 hours, anakinra reduced CRP by 61% versus baseline, compared with a 6% reduction among patients receiving placebo (P = 0.004 anakinra vs. placebo).

CONCLUSIONS

Interleukin-1 blockade with anakinra reduces the systemic inflammatory response in patients with ADHF. Further studies are warranted to determine whether this anti-inflammatory effect translates into improved clinical outcomes.

Exercise training decreases NADPH oxidase activity and restores skeletal muscle mass in heart failure rats

We have recently demonstrated that NADPH oxidase hyperactivity, NF-κB activation, and increased p38 phosphorylation lead to atrophy of glycolytic muscle in heart failure (HF). Aerobic exercise training (AET) is an efficient strategy to counteract skeletal muscle atrophy in this syndrome. Therefore, we tested whether AET would regulate muscle redox balance and protein degradation by decreasing NADPH oxidase hyperactivity and reestablishing NF-κB signaling, p38 phosphorylation, and proteasome activity in plantaris muscle of myocardial infarcted-induced HF (MI) rats. Thirty-two male Wistar rats underwent MI or fictitious surgery (SHAM) and were randomly assigned into untrained (UNT) and trained (T; 8 wk of AET on treadmill) groups. AET prevented HF signals and skeletal muscle atrophy in MI-T, which showed an improved exercise tolerance, attenuated cardiac dysfunction and increased plantaris fiber cross-sectional area. To verify the role of inflammation and redox imbalance in triggering protein degradation, circulating TNF-α levels, NADPH oxidase profile, NF-κB signaling, p38 protein levels, and proteasome activity were assessed. MI-T showed a reduced TNF-α levels, NADPH oxidase activity, and Nox2 mRNA expression toward SHAM-UNT levels. The rescue of NADPH oxidase activity induced by AET in MI rats was paralleled by reducing nuclear binding activity of the NF-κB, p38 phosphorylation, atrogin-1, mRNA levels, and 26S chymotrypsin-like proteasome activity. Taken together our data provide evidence for AET improving plantaris redox homeostasis in HF associated with a decreased NADPH oxidase, redox-sensitive proteins activation, and proteasome hyperactivity further preventing atrophy. These data reinforce the role of AET as an efficient therapy for muscle wasting in HF.

NEW & NOTEWORTHY This study demonstrates, for the first time, the contribution of aerobic exercise training (AET) in decreasing muscle NADPH oxidase activity associated with reduced reactive oxygen species production and systemic inflammation, which diminish NF-κB overactivation, p38 phosphorylation, and ubiquitin proteasome system hyperactivity. These molecular changes counteract plantaris atrophy in trained myocardial infarction-induced heart failure rats. Our data provide new evidence into how AET may regulate protein degradation and thus prevent skeletal muscle atrophy.

Endotoxin-activated cultured neonatal rat cardiomyocytes express functional surface-associated interleukin-1α

Interleukin-1 (IL-1) is a potent regulator of cardiovascular proliferation, apoptosis, contraction or production of inflammatory mediators. Thus, we investigated expression and function of IL-1 in cultured neonatal rat heart cells upon endotoxin stimulation. We show that cultured neonatal rat cardiomyocytes expressed IL—1α and IL—1β mRNA. The cells expressed functional cell-associated IL—1 activity and a specific anti-IL—1α-antibody inhibited the activity. Biologically active IL—1α was present at the cell surface of the cardiomyocytes, as indicated in co-culture experiments. Immunohistochemistry showed IL—1α-staining of the neonatal cardiomyocytes. Although the cells also expressed IL—1β mRNA, we did not detect IL—1β in the supernatants of cultured cardiomyocytes by ELISA or in immunohistochemical staining. Furthermore, neonatal and adult rat heart tissues expressed IL—1α mRNA, whereas fetal, but not adult, human cardiac tissues expressed detectable IL—1α mRNA. In contrast, IL-1β mRNA was present in rat and human fetal and adult samples. Furthermore, in patients with dilated or ischemic cardiomyopathy, we measured IL—1β, but not IL—1α, mRNA. These results provide evidence for the presence of functionally active IL—1α on the cell surface of neonatal rat cardiomyocytes and may suggest a differential role of IL—1α in regulation of cellular functions during development, aging and disease in rat and human heart cells.

Inflammatory and fibrotic responses of cardiac fibroblasts to myocardial damage associated molecular patterns (DAMPs)

Cardiac fibroblasts (CF) are well-established as key regulators of extracellular matrix (ECM) turnover in the context of myocardial remodelling and fibrosis. Recently, this cell type has also been shown to act as a sensor of myocardial damage by detecting and responding to damage-associated molecular patterns (DAMPs) upregulated with cardiac injury. CF express a range of innate immunity pattern recognition receptors (TLRs, NLRs, IL-1R1, RAGE) that are stimulated by a host of different DAMPs that are evident in the injured or remodelling myocardium. These include intracellular molecules released by necrotic cells (heat shock proteins, high mobility group box 1 protein, S100 proteins), proinflammatory cytokines (interleukin-1α), specific ECM molecules up-regulated in response to tissue injury (fibronectin-EDA, tenascin-C) or molecules modified by a pathological environment (advanced glycation end product-modified proteins observed with diabetes). DAMP receptor activation on fibroblasts is coupled to altered cellular function including changes in proliferation, migration, myofibroblast transdifferentiation, ECM turnover and production of fibrotic and inflammatory paracrine factors, which directly impact on the heart's ability to respond to injury. This review gives an overview of the important role played by CF in responding to myocardial DAMPs and how the DAMP/CF axis could be exploited experimentally and therapeutically.

Pathogenesis and treatment of the cardiorenal syndrome: Implications of L-arginine-nitric oxide pathway impairment

A highly complex interplay exists between the heart and kidney in the setting of both normal and abnormal physiology. In the context of heart failure, a pathophysiological condition termed the cardiorenal syndrome (CRS) exists whereby dysfunction in the heart or kidney can accelerate pathology in the other organ. The mechanisms that underpin CRS are complex, and include neuro-hormonal activation, oxidative stress and endothelial dysfunction. The endothelium plays a central role in the regulation of both cardiac and renal function, and as such impairments in endothelial function can lead to dysfunction of both these organs. In particular, reduced bioavailability of nitric oxide (NO) is a key pathophysiologic component of endothelial dysfunction. The synthesis of NO by the endothelium is critically dependent on the plasmalemmal transport of its substrate, L-arginine, via the cationic amino acid transporter-1 (CAT1). Impaired L-arginine-NO pathway activity has been demonstrated individually in heart and renal failure. Recent findings suggest abnormalities of the L-arginine-NO pathway also play a role in the pathogenesis of CRS and thus this pathway may represent a potential new target for the treatment of heart and renal failure.

Comparison of arrhythmogenicity and proinflammatory activity induced by intramyocardial or epicardial myoblast sheet delivery in a rat model of ischemic heart failure

Although cell therapy of the failing heart by intramyocardial injections of myoblasts to results in regenerative benefit, it has also been associated with undesired and prospectively fatal arrhythmias. We hypothesized that intramyocardial injections of myoblasts could enhance inflammatory reactivity and facilitate electrical cardiac abnormalities that can be reduced by epicardial myoblast sheet delivery. In a rat model of ischemic heart failure, myoblast therapy either by intramyocardial injections or epicardial cell sheets was given 2 weeks after occlusion of the coronary artery. Ventricular premature contractions (VPCs) were assessed, using an implanted three-lead electrocardiograph at 1, 7, and 14 days after therapy, and 16-point epicardial electropotential mapping (EEPM) was used to evaluate ventricular arrhythmogenicity under isoproterenol stress. Cardiac functioning was assessed by echocardiography. Both transplantation groups showed therapeutic benefit over sham therapy. However, VPCs were more frequent in the Injection group on day 1 and day 14 after therapy than in animals receiving epicardial or sham therapy (p < 0.05 and p < 0.01, respectively). EEPM under isoproterenol stress showed macroreentry at the infarct border area, leading to ventricular tachycardias in the Injection group, but not in the myoblast sheet- or sham-treated groups (p = 0.045). Both transplantation types modified the myocardial cytokine expression profile. In animals receiving epicardial myoblast therapy, selective reductions in the expressions of interferon gamma, interleukin (IL)-1β and IL12 were observed, accompanied by reduced infiltration of inflammatory CD11b- and CD68-positive leukocytes, compared with animals receiving myoblasts as intramyocardial injections. Intramyocardial myoblast delivery was associated with enhanced inflammatory and immunomodulatory reactivity and increased frequency of VPCs. In comparison to intramyocardial injection, the epicardial route may serve as the preferred method of skeletal myoblast transplantation to treat heart failure.

Intra-renal delivery of mesenchymal stem cells attenuates myocardial injury after reversal of hypertension in porcine renovascular disease

Introduction

Percutaneous transluminal renal angioplasty (PTRA) fails to fully improve cardiac injury and dysfunction in patients with renovascular hypertension (RVH). Mesenchymal stem cells (MSCs) restore renal function, but their potential for attenuating cardiac injury after reversal of RVH has not been explored. We hypothesized that replenishment of MSCs during PTRA would improve cardiac function and oxygenation, and decrease myocardial injury in porcine RVH.

Methods

Pigs were studied after 16 weeks of RVH, RVH treated 4 weeks earlier with PTRA with or without adjunct intra-renal delivery of MSC (10^6 cells), and controls. Cardiac structure, function (fast-computed tomography (CT)), and myocardial oxygenation (Blood-Oxygen-Level-Dependent- magnetic resonance imaging) were assessed in-vivo. Myocardial microvascular density (micro-CT) and myocardial injury were evaluated ex-vivo. Kidney venous and systemic blood levels of inflammatory markers were measured and their renal release calculated.

Results

PTRA normalized blood pressure, yet stenotic-kidney glomerular filtration rate, similarly blunted in RVH and RVH + PTRA, normalized only in PTRA + MSC-treated pigs. PTRA attenuated left ventricular remodeling, whereas myocardial oxygenation, subendocardial microvascular density, and diastolic function remained decreased in RVH + PTRA, but normalized in RVH + PTRA-MSC. Circulating isoprostane levels and renal release of inflammatory cytokines increased in RVH and RVH + PTRA, but normalized in RVH + PTRA-MSC, as did myocardial oxidative stress, inflammation, collagen deposition, and fibrosis.

Conclusions

Intra-renal MSC delivery during PTRA preserved stenotic-kidney function, reduced systemic oxidative stress and inflammation, and thereby improved cardiac function, oxygenation, and myocardial injury four weeks after revascularization, suggesting a therapeutic potential for adjunctive MSC delivery to preserve cardiac function and structure after reversal of experimental RVH.

Anti-inflammatory peptides from cardiac progenitors ameliorate dysfunction after myocardial infarction

Background

Cardiac cell therapy has been proposed as one of the new strategies against myocardial infarction. Although several reports showed improvement of the function of ischemic heart, the effects of cell therapy vary among the studies and the mechanisms of the beneficial effects are still unknown. Previously, we reported that clonal stem cell antigen‐1–positive cardiac progenitor cells exerted a therapeutic effect when transplanted into the ischemic heart. Our aims were to identify the cardiac progenitor‐specific paracrine factor and to elucidate the mechanism of its beneficial effect.

Methods and Results

By using an antibody array, we found that soluble junctional adhesion molecule‐A (JAM‐A) was abundantly secreted from cardiac progenitor cells. Pretreatment of neutrophils with conditioned medium from cultured cardiac progenitor cells or soluble JAM‐A inhibited transendothelial migration and reduced motility of neutrophils. These inhibitory effects were attenuated by anti–JAM‐A neutralizing antibody. Injection of cardiac progenitor cells into infarct heart attenuated neutrophil infiltration and expression of inflammatory cytokines. Injection of soluble JAM‐A–expressing, but not of JAM‐A siRNA–expressing, cardiac progenitor cells into the infarct heart prevented cardiac remodeling and reduced fibrosis area.

Conclusions

Soluble JAM‐A secreted from cardiac progenitor cells reduces infiltration of neutrophils after myocardial infarction and ameliorates tissue damage through prevention of excess inflammation. Our finding may lead to a new therapy for cardiovascular disease by using the anti‐inflammatory effect of JAM‐A.

Matrix metalloproteinase-9: Many shades of function in cardiovascular disease

Matrix metalloproteinase (MMP)-9, one of the most widely investigated MMPs, regulates pathological remodeling processes that involve inflammation and fibrosis in cardiovascular disease. MMP-9 directly degrades extracellular matrix (ECM) proteins and activates cytokines and chemokines to regulate tissue remodeling. MMP-9 deletion or inhibition has proven overall beneficial in multiple animal models of cardiovascular disease. As such, MMP-9 expression and activity is a common end point measured. MMP-9 cell-specific overexpression, however, has also proven beneficial and highlights the fact that little information is available on the underlying mechanisms of MMP-9 function. In this review, we summarize our current understanding of MMP-9 physiology, including structure, regulation, activation, and downstream effects of increased MMP-9. We discuss MMP-9 roles during inflammation and fibrosis in cardiovascular disease. By concentrating on the substrates of MMP-9 and their roles in cardiovascular disease, we explore the overall function and discuss future directions on the translational potential of MMP-9 based therapies.

Cardiac fibroblast in development and wound healing

Cardiac fibroblasts are the most abundant cell type in the mammalian heart and comprise approximately two-thirds of the total number of cardiac cell types. During development, epicardial cells undergo epithelial-mesenchymal-transition to generate cardiac fibroblasts that subsequently migrate into the developing myocardium to become resident cardiac fibroblasts. Fibroblasts form a structural scaffold for the attachment of cardiac cell types during development, express growth factors and cytokines and regulate proliferation of embryonic cardiomyocytes. In post natal life, cardiac fibroblasts play a critical role in orchestrating an injury response. Fibroblast activation and proliferation early after cardiac injury are critical for maintaining cardiac integrity and function, while the persistence of fibroblasts long after injury leads to chronic scarring and adverse ventricular remodeling. In this review, we discuss the physiologic function of the fibroblast during cardiac development and wound healing, molecular mediators of activation that could be possible targets for drug development for fibrosis and finally the use of reprogramming technologies for reversing scar. This article is part of a Special Issue entitled "Myocyte-Fibroblast Signalling in Myocardium."

Effects of interleukin-1 on cardiac fibroblast function: relevance to post-myocardial infarction remodelling

The cardiac fibroblast (CF) is a multifunctional and heterogeneous cell type that plays an essential role in regulating cardiac development, structure and function. Following myocardial infarction (MI), the myocardium undergoes complex structural remodelling in an attempt to repair the damaged tissue and overcome the loss of function induced by ischemia/reperfusion injury. Evidence is emerging that CF play critical roles in all stages of post-MI remodelling, including the initial inflammatory phase that is triggered in response to myocardial damage. CF are particularly responsive to the proinflammatory cytokine interleukin-1 (IL-1) whose levels are rapidly induced in the myocardium after MI. Studies from our laboratory in recent years have sought to evaluate the functional effects of IL-1 on human CF function and to determine the underlying molecular mechanisms. This review summarises these data and sets it in the context of post-MI cardiac remodelling, identifying the fibroblast as a potential therapeutic target for reducing adverse cardiac remodelling and its devastating consequences.

IL-1β suppresses TGF-β-mediated myofibroblast differentiation in cardiac fibroblasts

Cardiac fibrosis is a maladaptive response of the injured myocardium and is mediated through a complex interplay between molecular triggers and cellular responses. Interleukin (IL)-1β is a key inflammatory inducer in cardiac disease and promotes cell invasion and cardiomyocyte injury, but little is known of its impact on fibrosis. A major cornerstone of fibrosis is the differentiation of cardiac fibroblasts (CFs) into myofibroblasts (myoFbs), which is highly promoted by Transforming Growth Factor (TGF)-β. Therefore, we asked how IL-1β functionally modulated CF-to-myoFb differentiation. Using a differentiation model of ventricular fibroblasts, we found that IL-1β instigated substantial anti-fibrogenic effects. In specific, IL-1β reduced proliferation, matrix activity, cell motility and α-smooth muscle actin expression, which are all hallmarks of myoFb differentiation. These findings suggest that IL-1β, besides from its acknowledged adverse role in the inflammatory response, can also exert beneficial effects in cardiac fibrosis by actively suppressing differentiation of CFs into fibrogenic myoFbs.

Inflammatory activation: cardiac, renal, and cardio-renal interactions in patients with the cardiorenal syndrome

Although inflammation is a physiologic response designed to protect us from infection, when unchecked and ongoing it may cause substantial harm. Both chronic heart failure (CHF) and chronic kidney disease (CKD) are known to cause elaboration of several pro-inflammatory mediators that can be detected at high concentrations in the tissues and blood stream. The biologic sources driving this chronic inflammatory state in CHF and CKD are not fully established. Traditional sources of inflammation include the heart and the kidneys which produce a wide range of pro-inflammatory cytokines in response to neurohormones and sympathetic activation. However, growing evidence suggests that non-traditional biomechanical mechanisms such as venous and tissue congestion due to volume overload are also important as they stimulate endotoxin absorption from the bowel and peripheral synthesis and release of pro-inflammatory mediators. Both during the chronic phase and, more rapidly, during acute exacerbations of CHF and CKD, inflammation and congestion appear to amplify each other resulting in a downward spiral of worsening cardiac, vascular, and renal functions that may negatively impact patients' outcome. Anti-inflammatory treatment strategies aimed at attenuating end organ damage and improving clinical prognosis in the cardiorenal syndrome have been disappointing to date. A new therapeutic paradigm may be needed, which involves different anti-inflammatory strategies for individual etiologies and stages of CHF and CKD. It may also include specific (short-term) anti-inflammatory treatments that counteract inflammation during the unsettled phases of clinical decompensation. Finally, it will require greater focus on volume overload as an increasingly significant source of systemic inflammation in the cardiorenal syndrome.

Interleukin-1 has opposing effects on connective tissue growth factor and tenascin-C expression in human cardiac fibroblasts

Cardiac fibroblasts (CF) play a central role in the repair and remodeling of the heart following injury and are important regulators of inflammation and extracellular matrix (ECM) turnover. ECM-regulatory matricellular proteins are synthesized by several myocardial cell types including CF. We investigated the effects of pro-inflammatory cytokines on matricellular protein expression in cultured human CF. cDNA array analysis of matricellular proteins revealed that interleukin-1α (IL-1α, 10ng/ml, 6h) down-regulated connective tissue growth factor (CTGF/CCN2) mRNA by 80% and up-regulated tenascin-C (TNC) mRNA levels by 10-fold in human CF, without affecting expression of thrombospondins 1-3, osteonectin or osteopontin. Western blotting confirmed these changes at the protein level. In contrast, tumor necrosis factor α (TNFα) did not modulate CCN2 expression and had only a modest stimulatory effect on TNC levels. Signaling pathway inhibitor studies suggested an important role for the p38 MAPK pathway in suppressing CCN2 expression in response to IL-1α. In contrast, multiple signaling pathways (p38, JNK, PI3K/Akt and NFκB) contributed to IL-1α-induced TNC expression. In conclusion, IL-1α reduced CCN2 expression and increased TNC expression in human CF. These observations are of potential value for understanding how inflammation and ECM regulation are linked at the level of the CF.

Remote ischemic preconditioning regulates HIF-1α levels, apoptosis and inflammation in heart tissue of cardiosurgical patients: a pilot experimental study

Transient episodes of ischemia in a remote organ (remote ischemic preconditioning, RIPC) bears the potential to attenuate myocardial injury, but the underlying mechanisms are only poorly understood. In the pilot experimental study presented we investigated cellular and molecular effects of RIPC in heart tissue of cardiosurgical patients with cardiopulmonary bypass (CPB) and focussed on apoptotic events, local and systemic inflammation as well as the regulation of the hypoxia induced factor-1α (HIF-1α). RIPC was induced by four 5-min cycles of transient upper limb ischemia/reperfusion using a blood-pressure cuff. Right atrial tissue and serum were obtained from patients receiving RIPC (N = 32) and control patients (N = 29) before and after CPB. RIPC patients showed reduced troponin T serum concentrations in the first 48 h after surgery (P < 0.05 vs. control) indicating cardioprotective effects of RIPC. Samples from RIPC patients that were collected before CPB contained significantly increased amounts of HIF-1α and procaspase-3 (HIF-1α: P < 0.05 vs. control, procaspase-3: P < 0.05 vs. control), whereas activities of caspases 3 and 7 were by trend reduced. Samples from RIPC patients that were taken after CPB showed an increased activity of myeloperoxidase (P < 0.05 vs. control; P < 0.05 vs. RIPC before CPB) as well as elevated tissue concentrations of the interleukin (IL)-1β (P < 0.05 vs. RIPC before CPB). Serum levels of IL-8, IL-1β and TNFα were significantly increased in RIPC patients before CPB (P < 0.05 vs. control before CPB). In summary, RIPC regulates HIF-1α levels, apoptosis and inflammation in the myocardium of cardiosurgical patients and leads to increased concentrations of circulating cytokines.

Enhanced interleukin-1 activity contributes to exercise intolerance in patients with systolic heart failure

BACKGROUND

Heart failure (HF) is a complex clinical syndrome characterized by impaired cardiac function and poor exercise tolerance. Enhanced inflammation is associated with worsening outcomes in HF patients and may play a direct role in disease progression. Interleukin-1β (IL-1β) is a pro-inflammatory cytokine that becomes chronically elevated in HF and exerts putative negative inotropic effects.

METHODS AND RESULTS

We developed a model of IL-1β-induced left ventricular (LV) dysfunction in healthy mice that exhibited a 32% reduction in LV fractional shortening (P<0.001) and a 76% reduction in isoproterenol response (P<0.01) at 4 hours following a single dose of IL-1β 3 mcg/kg. This phenotype was reproducible in mice injected with plasma from HF patients and fully preventable by pretreatment with IL-1 receptor antagonist (anakinra). This led to the design and conduct of a pilot clinical to test the effect of anakinra on cardiopulmonary exercise performance in patients with HF and evidence of elevated inflammatory signaling (n = 7). The median peak oxygen consumption (VO(2)) improved from 12.3 [10.0, 15.2] to 15.1 [13.7, 19.3] mL · kg(-1) · min(-1) (P = 0.016 vs. baseline) and median ventilator efficiency (V(E)/VCO(2) slope) improved from 28.1 [22.8, 31.7] to 24.9 [22.9, 28.3] (P = 0.031 vs. baseline).

CONCLUSIONS

These findings suggest that IL-1β activity contributes to poor exercise tolerance in patients with systolic HF and identifies IL-1β blockade as a novel strategy for pharmacologic intervention.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01300650.

MicroRNA involvement in immune activation during heart failure

Heart failure is one of the common end stages of cardiovascular diseases, the leading cause of death in developed countries. Molecular mechanisms underlying the development of heart failure remain elusive but there is a consistent observation of chronic immune activation and aberrant microRNA (miRNA) expression that is present in failing hearts. This review will focus on the interplay between the immune system and miRNAs as factors that play a role during the development of heart failure. Several studies have shown that heart failure patients can be characterized by a sustained innate immune activation. The role of inflammatory signaling is discussed and TLR4 signaling, IL-1β, TNFα and IL-6 expression appears to coincide with the development of heart failure. Furthermore, we describe the implication of the renin angiotensin aldosteron system in immunity and heart failure. In the past decade microRNAs (miRNAs), small non-coding RNAs that translationally repress protein synthesis by binding to partially complementary sequences of mRNA, have come to light as important regulators of several kinds of cardiovascular diseases including cardiac hypertrophy and heart failure. The involvement of differentially expressed miRNAs in the inflammation that occurs during the development of heart failure is still subject of investigation. Here, we summarize and comment on the first studies in this field and hypothesize on the putative involvement of certain miRNAs in heart failure. MicroRNAs have been shown to be critical regulators of cardiac function and inflammation. Future research will have to point out if dampening the immune response, and the miRNAs associated with it, during the development of heart failure is a therapeutically plausible route to follow.

Association of IL1B polymorphism with left ventricular systolic dysfunction: a relation with the release of interleukin-1β in stress condition

OBJECTIVE

Proinflammatory cytokines play a major role in the pathomechanisms of heart failure. Besides this, the influence of mental stress on heart failure is poorly documented despite its effects on sympathetic stimulation of interleukin-1β (IL-1β) secretion. We examined whether the polymorphisms of proinflammatory cytokines are predictors of left ventricular systolic dysfunction (LVSD) and if so, whether such associations are related to the secretion of these cytokines, in 572 consecutive patients under mental stress produced by coronary angiography.

METHODS

We examined IL-1RN (VNTR), IL1A-889 C>T, IL1B-511 C>T, IL6-174 G>C and TNFA-308 G>A, according to LVSD (left ventricular ejection fraction, <40%). Saliva IL-1β, serum tumour necrosis factor-α and C-reactive protein were assayed in basal (T0 and T2, before and after coronary angiography) and stress (T1) conditions.

MAIN RESULTS

The 42.1% of patients with LVSD had a 1.5-fold higher frequency of IL1B T allele (P<0.001). IL1B-511TT was associated with LVSD (P=0.008) and with a decrease in IL-1β level in saliva at T1 (P=0.013). IL-1β was the highest at T1 (P<0.001) and was associated with left ventricular ejection fraction (P=0.002). The IL1B TT genotype and the C-reactive protein were the two independent predictors of LVSD in multivariate analysis, with an odds ratio of 2.7 (95% confidence interval: 1.3-5.5; P=0.008) and 1.1 (95% confidence interval: 1.1-1.2; P<0.001), respectively.

CONCLUSION

IL1B was a predictor of LVSD and of the decreased IL-1β response to stress. This suggests that IL1B exerts an influence on LVSD through its effect on IL-1β secretion.

Crosstalk between leptin and interleukin-1β abrogates negative inotropic effects in a model of chronic hyperleptinemia

Interleukin 1 beta (IL-1 β) is a proinflammatory cytokine with potent cardiosuppressive effects. Previous studies have shown that leptin blunts the negative inotropic effects of IL-1 β in isolated adult rat cardiac myocytes. However, the interactions between leptin and IL-1 β in the heart have not been examined on a background of chronic hyperleptinemia. To study this interaction, we have chosen the SHHF rat, a model of spontaneous hypertension that ultimately develops congestive heart failure. SHHF that are heterozygous for a null mutation of the leptin receptor (+/ fa cp, HET) are phenotypically lean but chronically hyperleptinemic and develop heart failure earlier than their normoleptinemic true lean (+/+, LN) littermates. Simultaneous cell shortening and calcium transients were measured in isolated ventricular cardiac myocytes from LN and HET SHHF in response to leptin, IL-1 β or IL-1 β following one hour pretreatment with leptin. Despite evidence of metabolic leptin resistance, HET myocytes were sensitive to the negative inotropic effect of leptin, similar to LN. Contractility returned to control levels in myocytes from HET that were pretreated with leptin prior to IL-1 β, while contractility remained depressed compared with control and similar to leptin alone in LN. Chronic hyperleptinemia resulted in altered JAK/STAT signaling in response to leptin and IL-1 β in isolated perfused hearts from HET compared with LN SHHF. Phosphorylated STAT3 (pSTAT3) and STAT5 (pSTAT5) decreased when HET hearts were treated with leptin followed by IL-1 β. While decreases in pSTAT3 and pSTAT5 may be associated with abrogation of the acute negative inotropic effects of IL-1 β in the presence of leptin in HET, long-term consequences remain to be explored. This study demonstrates that the heart remains sensitive to leptin in a hyperleptinemic state. Crosstalk between leptin and IL-1 β can influence cardiac function and cytokine signaling and these interactions are moderated by the presence of long-term hyperleptinemia.

The TIR/BB-loop mimetic AS-1 prevents cardiac hypertrophy by inhibiting IL-1R-mediated MyD88-dependent signaling

Activation of NF-κB contributes to cardiac hypertrophy and the interleukin-1 receptor (IL-1R)-mediated MyD88-dependent signaling pathway predominately activates NF-κB. Recent studies have shown that the TIR/BB-Loop mimetic (AS-1) disrupted the interaction of MyD88 with the IL-1R, resulting in blunting of NF-κB activation. We have examined the effects of AS-1 on the IL-1β-induced hypertrophic response using cultured neonatal cardiac myocytes in vitro and transverse aortic constriction (TAC) pressure overload-induced cardiac hypertrophy in vivo. Neonatal cardiac myocytes were treated with AS-1 15 min prior to IL-1β stimulation for 24 h. AS-1 treatment significantly attenuated IL-1β-induced hypertrophic responses of cardiac myocytes. In vivo experiments showed that AS-1 administration prevented cardiac hypertrophy and dysfunction induced by pressure overload. AS-1 administration disrupted the interaction of IL-1R with MyD88 in the pressure overloaded hearts and prevented activation of NF-κB. In addition, AS-1 prevented increases in activation of the MAPK pathway (p38 and p-ERK) in TAC-induced hypertrophic hearts. Our data suggest that the IL-1R-mediated MyD88-dependent signaling pathway plays a role in the development of cardiac hypertrophy and AS-1 attenuation of cardiac hypertrophy is mediated by blocking the interaction between IL-1R and MyD88, resulting in decreased NF-κB binding activity and decreased MAPK activation.

Left ventricular remodeling in the post-infarction heart: a review of cellular, molecular mechanisms, and therapeutic modalities

As more patients survive myocardial infarctions, the incidence of heart failure increases. After an infarction, the human heart undergoes a series of structural changes, which are governed by cellular and molecular mechanisms in a pathological metamorphosis termed "remodeling." This review will discuss the current developments in our understanding of these molecular and cellular events in remodeling and the various pharmacological, cellular and device therapies used to treat, and potentially retard, this condition. Specifically, this paper will examine the neurohormonal activity of the renin-angiotensin-aldosterone axis and its molecular effects on the heart. The emerging understanding of the extra-cellular matrix and the various active molecules within it, such as the matrix metalloproteinases, elicits new appreciation for their role in cardiac remodeling and as possible future therapeutic targets. Cell therapy with stem cells is another recent therapy with great potential in improving post-infarcted hearts. Lastly, the cellular and molecular effects of left ventricular assist devices on remodeling will be reviewed. Our increasing knowledge of the cellular and molecular mechanisms underlying cardiac remodeling enables us not only to better understand how our more successful therapies, like angiotensin-converting enzyme inhibitors, work, but also to explore new therapies of the future.

Origins of cardiac fibroblasts

Cardiac fibroblasts play a critical role in maintenance of normal cardiac function. They are indispensable for damage control and tissue remodeling on myocardial injury and principal mediators of pathological cardiac remodeling and fibrosis. Despite their manyfold functions, cardiac fibroblasts remain poorly characterized in molecular terms. Evidence is evolving that cardiac fibroblasts are a heterogeneous population and likely derive from various distinct tissue niches in health and disease. Here, we review our emerging understanding of where cardiac fibroblasts come from, as well as how we can possibly use this knowledge to develop novel therapies for cardiac fibrosis.

Intragraft gene expression profile associated with the induction of tolerance by allochimeric MHC I in the rat heart transplantation model

The MHC class I allochimeric protein containing donor-type epitopes on recipient-type heavy chains induces indefinite survival of heterotopic cardiac allografts in rats. We analyzed gene expression profile of heart allograft tissue. Mutated peptide [alpha1h1/u]-RT1.Aa that contains donor-type (Wistar Furth, WF; RT1u) immunogenic epitopes displayed on recipient-type (ACI, RT1a) was delivered into ACI recipients of WF hearts at the time of transplantation in addition to a 3 days course of oral cyclosporine. Microarray analysis was performed using Affymetrix Rat 230 2.0 Microarray. Allochimeric molecule treatment caused upregulation of genes involved in structural integrity of heart muscle, downregulation of IL-1beta a key modulator of the immune response, and downregulation of partitioning defective six homolog gamma PAR6, which is involved in T cell polarity, motility, and ability to scan dendritic cells (DC). These indicate that the immunosuppressive function of allochimeric molecule and/or the establishment of allograft tolerance depend on the induction of genes responsible for the heart tissue integrity, the suppression of cytokine pathway(s), and possibly the impairment of T cells mobility and their DC scanning ability. These novel findings may have important clinical implications for inhibition of chronic rejection in transplant recipients.

Angiotensin II enhances interleukin-1 beta-induced MMP-9 secretion in adult rat cardiac fibroblasts

Cardiac fibroblasts play important roles during the cardiac remodeling through the secretion of matrix metalloproteinase (MMP)-9. Inflammatory cytokine, interleukin (IL)-1beta induces MMP-9 secretion in cultured cardiac fibroblasts. Angiotensin II is well known to play pivotal roles in cardiac remodeling, but the effect of angiotensin II on MMP-9 secretion in cardiac fibroblasts has not been fully clarified. In the present study, we investigated the effect of angiotensin II on basal and IL-1beta-induced MMP-9 secretion in adult rat cardiac fibroblasts. MMP-9 protein secreted into culture medium, and phosphorylation of nuclear factor (NF)-kappaB, c-Jun NH(2)-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK) in cell lysates were measured by Western blotting. Angiotensin II (1 nM, 24 hr) alone-treatment did not induce MMP-9 secretion. However, angiotensin II significantly enhanced IL-1beta (4 ng/ml, 24 hr)-induced MMP-9 secretion. Telmisartan (10 nM), an angiotensin II type 1 receptor (AT1R) antagonist, significantly suppressed the enhancement of IL-1beta-induced MMP-9 secretion by angiotensin II, whereas PD123319 (10 nM), an angiotensin II type 2 receptor antagonist, was ineffective. IL-1beta (4 ng/ml, 10 min) induced phosphorylation of NF-kappaB, JNK, and ERK. Angiotensin II augmented the IL-1beta-induced phosphorylation of ERK but not NF-kappaB and JNK. PD98059 (50 microM), a selective inhibitor of ERK pathway, inhibited the angiotensin II enhancement of IL-1beta-induced MMP-9 secretion. These results suggest that angiotensin II enhances IL-1beta-induced MMP-9 secretion through the augmentation of ERK phosphorylation via AT1R in adult rat cardiac fibroblasts.

Cardiac fibroblast: the renaissance cell

The permanent cellular constituents of the heart include cardiac fibroblasts, myocytes, endothelial cells, and vascular smooth muscle cells. Previous studies have demonstrated that there are undulating changes in cardiac cell populations during embryonic development, through neonatal development and into the adult. Transient cell populations include lymphocytes, mast cells, and macrophages, which can interact with these permanent cell types to affect cardiac function. It has also been observed that there are marked differences in the makeup of the cardiac cell populations depending on the species, which may be important when examining myocardial remodeling. Current dogma states that the fibroblast makes up the largest cell population of the heart; however, this appears to vary for different species, especially mice. Cardiac fibroblasts play a critical role in maintaining normal cardiac function, as well as in cardiac remodeling during pathological conditions such as myocardial infarct and hypertension. These cells have numerous functions, including synthesis and deposition of extracellular matrix, cell-cell communication with myocytes, cell-cell signaling with other fibroblasts, as well as with endothelial cells. These contacts affect the electrophysiological properties, secretion of growth factors and cytokines, as well as potentiating blood vessel formation. Although a plethora of information is known about several of these processes, relatively little is understood about fibroblasts and their role in angiogenesis during development or cardiac remodeling. In this review, we provide insight into the various properties of cardiac fibroblasts that helps illustrate their importance in maintaining proper cardiac function, as well as their critical role in the remodeling heart.

Cardiac fibroblasts: at the heart of myocardial remodeling

Cardiac fibroblasts are the most prevalent cell type in the heart and play a key role in regulating normal myocardial function and in the adverse myocardial remodeling that occurs with hypertension, myocardial infarction and heart failure. Many of the functional effects of cardiac fibroblasts are mediated through differentiation to a myofibroblast phenotype that expresses contractile proteins and exhibits increased migratory, proliferative and secretory properties. Cardiac myofibroblasts respond to proinflammatory cytokines (e.g. TNFalpha, IL-1, IL-6, TGF-beta), vasoactive peptides (e.g. angiotensin II, endothelin-1, natriuretic peptides) and hormones (e.g. noradrenaline), the levels of which are increased in the remodeling heart. Their function is also modulated by mechanical stretch and changes in oxygen availability (e.g. ischaemia-reperfusion). Myofibroblast responses to such stimuli include changes in cell proliferation, cell migration, extracellular matrix metabolism and secretion of various bioactive molecules including cytokines, vasoactive peptides and growth factors. Several classes of commonly prescribed therapeutic agents for cardiovascular disease also exert pleiotropic effects on cardiac fibroblasts that may explain some of their beneficial outcomes on the remodeling heart. These include drugs for reducing hypertension (ACE inhibitors, angiotensin receptor blockers, beta-blockers), cholesterol levels (statins, fibrates) and insulin resistance (thiazolidinediones). In this review, we provide insight into the properties of cardiac fibroblasts that underscores their importance in the remodeling heart, including their origin, electrophysiological properties, role in matrix metabolism, functional responses to environmental stimuli and ability to secrete bioactive molecules. We also review the evidence suggesting that certain cardiovascular drugs can reduce myocardial remodeling specifically via modulatory effects on cardiac fibroblasts.

Cardiac cell-specific apoptotic and cytokine responses to reovirus infection: determinants of myocarditic phenotype

BACKGROUND

The pathophysiologic mechanisms underlying viral myocarditis are not well defined. As a result, effective treatments do not exist and viral myocarditis remains a potentially lethal infection of the heart.

METHODS AND RESULTS

We used cultured rat cardiac myocytes and fibroblasts to investigate apoptosis and cytokine production in response to infection by myocarditic vs. non-myocarditic strains of reovirus. Myocarditic reovirus strain 8B and non-myocarditic strain DB188 replicate comparably in each cardiac cell type. However, strain 8B and related myocarditic reoviruses preferentially increase apoptosis of myocytes relative to fibroblasts, whereas DB188 and nonmyocarditic strains preferentially increase fibroblast apoptosis. Infection of cardiac fibroblasts with the nonmyocarditic strain DB188 elicits substantial increases in a panel of cytokines compared to fibroblasts infected with strain 8B or mock-infected controls. Analysis of culture supernatants using cytometric bead arrays revealed that DB188 enhanced release of interleukin (IL)-1beta, IL-4, IL-6, IL-10, IL-12(p70), GRO-KC, tumor necrosis factor-alpha, and MCP-1 relative to 8B or mock-infected controls (all P < .05).

CONCLUSION

We hypothesize that differential cytokine production and cell-specific apoptosis are important determinants of myocarditic potential of reoviral strains. Therapies that target the beneficial effects of cytokines in limiting cytopathic damage may offer an effective and novel treatment approach to viral myocarditis.

Prolonged administration of a dithiol antioxidant protects against ventricular remodeling due to ischemia-reperfusion in mice

The prolonged production of reactive oxygen species due to ischemia-reperfusion (I/R) is a potential cause of the pathological remodeling that frequently precedes heart failure. We tested the ability of a potent dithiol antioxidant, bucillamine, to protect against the long-term consequences of I/R injury in a murine model of myocardial infarction. After transiently occluding the left anterior descending coronary artery for 30 min, saline or bucillamine (10 microg/g body wt) was injected intravenously as a bolus within the first 5 min of reperfusion. The antioxidant treatment continued with daily subcutaneous injections for 4 wk. There were no differences in infarct sizes between bucillamine- and saline-treated animals. After 4 wk of reperfusion, cardiac hypertrophy was decreased by bucillamine treatment (ventricular weight-to-body weight ratios: I/R + saline, 4.5 +/- 0.2 mg/g vs. I/R + bucillamine, 4.2 +/- 0.1 mg/g; means +/- SE; P < 0.05). Additionally, the hearts of bucillamine-treated mice had improved contractile function (echocardiographic measurement of fractional shortening) relative to saline controls: I/R + saline, 32 +/- 3%, versus I/R + bucillamine, 41 +/- 4% (P < 0.05). Finally, I/R-induced injury in the saline-treated mice was accompanied by a fetal pattern of gene expression determined by ribonuclease protection assay that was consistent with pathological cardiac hypertrophy and remodeling [increased atrial natriuretic peptide, beta-myosin heavy chain (MHC), skeletal alpha-actin; decreased sarco(endo)plasmic reticulum Ca2+ ATPase 2a, and alpha-MHC-to-beta-MHC ratio]. These changes in gene expression were significantly attenuated by bucillamine. Therefore, treatment with a dithiol antioxidant for 4 wk after I/R preserved ventricular function and prevented the abnormal pattern of gene expression associated with pathological cardiac remodeling.

Leptin modulates the negative inotropic effect of interleukin-1beta in cardiac myocytes

Interleukin-1beta (IL-1beta) is a potent negative inotrope implicated in the functional abnormalities of heart failure. Because the adipokine, leptin, protects against some of the cardiovascular effects of endotoxin, we hypothesized that leptin may modulate the cardiosuppressive effects of IL-1beta in isolated cardiomyocytes. Ventricular cardiac myocytes isolated from adult male Sprague Dawley rats were analyzed simultaneously for electrically stimulated contractility and calcium transients following 30 min exposure to IL-1beta (10 ng/ml) with or without 60 min pretreatment with leptin (25 ng/ml). IL-1beta decreased cell shortening, depressed maximal velocities of shortening and relengthening, and prolonged the time to 90% relaxation. The change in fura2-AM fluorescence ratio amplitude (Delta[Ca(2+)]) was significantly depressed and the time to return to baseline [Ca(2+)] was prolonged. The negative inotropic effects of IL-1beta were blocked by the neutral sphingomyelinase inhibitor Manumycin A (5 microM) or the ceramidase inhibitor N-oleoyl ethanolamine (1 microM). Prior exposure of myocytes to leptin blocked IL-1beta-induced cardiosuppression in conjunction with a blunting of IL-1beta stimulated ceramide accumulation. These data suggest that leptin may modulate IL-1beta signaling through the sphingolipid signaling pathway in cardiomyocytes.

Altered interleukin-1 receptor antagonist and interleukin-18 mRNA expression in myocardial tissues of patients with dilatated cardiomyopathy

Interleukin-1 (IL-1) is a potent regulator of cell proliferation, inflammation, and contraction of cardiovascular cells. It has been proposed that the IL-1/IL-1ra (IL-1 receptor antagonist) ratio influences these functions. Other members of the IL-1 family and the related caspase-1 also contribute to regulation of IL-1-mediated functions. We determined the mRNA expression of caspase-1, caspase-3, IL-1alpha , IL-1beta , IL-18, IL-1 receptor type I (IL-1-RI), and IL-1ra in left ventricle tissue of hearts from patients with ischemic or dilated cardiomyopathy (ICM or DCM) and in control tissues from unused donor transplant hearts in RT-PCR experiments. We show that the expression of caspase-1, caspase-3, IL-1beta , and IL-1-RI mRNA was not different between patients and control tissues. Furthermore, we did not find detectable amounts of IL-1alpha mRNA in any of these adult myocardial tissues. On the other hand, expression of IL-18 RNA was lower in myocardium of both patient groups compared with control hearts. Furthermore, IL-1ra mRNA expression was significantly lower in tissues of DCM patients compared with ICM patients and controls. This was in line with a trend towards lower IL-1ra protein levels in myocardial tissues of DCM patients. In contrast with the adult tissues discussed above, which did not express IL-1alpha mRNA, commercially available human fetal tissue expressed IL-1alpha mRNA. On the other hand IL-1beta mRNA was present in fetal and in adult human heart tissue. Our data provide evidence for an altered ratio of IL-1/IL-1ra in DCM patients. This dysregulation may contribute to pathogenesis and/or progression of heart disease by modulating the otherwise balanced IL-1-mediated functions in cardiovascular cells.

Myocardial Matrix Remodeling and the Matrix Metalloproteinases: Influence on Cardiac Form and Function

It is now becoming apparent that dynamic changes occur within the interstitium that directly contribute to adverse myocardial remodeling following myocardial infarction (MI), with hypertensive heart disease and with intrinsic myocardial disease such as cardiomyopathy. Furthermore, a family of matrix proteases, the matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs), has been recognized to play an important role in matrix remodeling in these cardiac disease states. The purpose of this review is fivefold: 1) to examine and redefine the myocardial matrix as a critical and dynamic entity with respect to the remodeling process encountered with MI, hypertension, or cardiomyopathic disease; 2) present the remarkable progress that has been made with respect to MMP/TIMP biology and how it relates to myocardial matrix remodeling; 3) to evaluate critical translational/clinical studies that have provided a cause-effect relationship between alterations in MMP/TIMP regulation and myocardial matrix remodeling; 4) to provide a critical review and analysis of current diagnostic, prognostic, and pharmacological approaches that utilized our basic understanding of MMP/TIMPs in the context of cardiac disease; and 5) most importantly, to dispel the historical belief that the myocardial matrix is a passive structure and supplant this belief that the regulation of matrix protease pathways such as the MMPs and TIMPs will likely yield a new avenue of diagnostic and therapeutic strategies for myocardial remodeling and the progression to heart failure.

Evaluation of immunomodulatory biomarkers in a pressure overload model of heart failure

STUDY OBJECTIVES

To characterize the immunomodulatory response in a pressure overload model of heart failure, and to further validate this animal model of human heart failure.

DESIGN

Randomized, controlled, animal study.

SETTING

Large university research facility.

ANIMALS

Twenty-seven, male, Sprague-Dawley rats.

INTERVENTION

The rats underwent either aortic constriction or a sham procedure.

MEASUREMENTS AND MAIN RESULTS

Six months after the surgical procedure, echocardiographic measurements were obtained, the animals were sacrificed, and plasma samples were taken to measure concentrations of biomarkers. As six (40%) of the 15 rats in the aortic-constriction group died before the 6 months, only nine rats from this group underwent immunomodulatory evaluation. Compared with the sham procedure, aortic constriction increased the left ventricle:body weight ratio in the rats (p=0.0016) It also decreased the velocity of circumferential shortening (p=0.08) and increased myocardial expression of atrial natriuretic factor, beta-myosin heavy chain, and fibronectin (p<0.05). Concentrations of the proinflammatory mediator interleukin (IL)-1beta and the counterregulatory mediator IL-10 also significantly increased (p<0.04) in the group that underwent aortic constriction compared with the group that underwent the sham procedure. Nonsignificant increases (mean change approximately 50-180%) were also observed for IL-2, IL-6, and leptin concentrations.

CONCLUSIONS

In this classic animal model of heart failure, a systemic immunomodulatory response was evaluated after 6 months of pressure overload resulting in myocardial decompensation and, in some cases, mortality. The findings are similar to the immunomodulatory response that may be observed in human heart failure. These novel results further define this model of heart failure and suggest another aspect of its relevance to human heart failure with regard to pressure overload and the immunomodulatory response.