TNF alpha receptor expression in rat cardiac myocytes: TNF alpha inhibition of L-type Ca2+ current and Ca2+ transients

Role of the lectin-like domain of thrombomodulin in septic cardiomyopathy

AIMS

Septic cardiomyopathy is a severe complication of sepsis and septic shock. This study aimed to evaluate the role of thrombomodulin and its lectin-like domain (LLD-TM) in the development of septic cardiomyopathy and the link between LLD-TM, HMGB-1, and toll-like receptors 2/4 (TLR 2/4) to intracellular mechanisms resulting in reduced cardiac function.

MATERIALS AND METHODS

Sepsis was induced using a polymicrobial peritoneal infection model in wildtype and mice lacking the lectin-like domain of thrombomodulin (TM^LeD/LeD), and severity of disease and cardiac function was compared. Cell cultures of cardiomyocytes were prepared from hearts harvested from wildtype and TM^LeD/LeD mice. Cultures of neonatal cardiomyocytes were transfected with complete human thrombomodulin or human thrombomodulin deficient of LLD-TM and when TLR-2 and/or TLR-4 were blocked. All cultures were challenged with inflammatory stimuli.

KEY FINDINGS

Lack of the LLD-TM results in a significant increase in severity of disease, decreased survival and impaired cardiac function in septic mice. In vivo and in vitro analyses of cardiomyocytes displayed high levels of inflammatory cytokines causing cardio-depression. In vitro results showed a strong correlation between elevated HMGB-1 levels and elevated troponin-1 levels. No connection was found between HMGB-1 and TLR-2 and/or -4 signalling pathways. Phospholamban mediated dysregulation of calcium homeostasis resulted in a general impairment after sepsis induction, but showed no connection to LLD-TM.

SIGNIFICANCE

Lack of LLD-TM results in an increase in general severity of disease, decreased survival and impaired cardiac function in sepsis. TLR-2 and TLR 4 do not participate as mediating factors in the development of septic cardiomyopathy.

Early Protective Role of Inflammation in Cardiac Remodeling and Heart Failure: Focus on TNFα and Resident Macrophages

Cardiac hypertrophy, initiated by a variety of physiological or pathological stimuli (hemodynamic or hormonal stimulation or infarction), is a critical early adaptive compensatory response of the heart. The structural basis of the progression from compensated hypertrophy to pathological hypertrophy and heart failure is still largely unknown. In most cases, early activation of an inflammatory program reflects a reparative or protective response to other primary injurious processes. Later on, regardless of the underlying etiology, heart failure is always associated with both local and systemic activation of inflammatory signaling cascades. Cardiac macrophages are nodal regulators of inflammation. Resident macrophages mostly attenuate cardiac injury by secreting cytoprotective factors (cytokines, chemokines, and growth factors), scavenging damaged cells or mitochondrial debris, and regulating cardiac conduction, angiogenesis, lymphangiogenesis, and fibrosis. In contrast, excessive recruitment of monocyte-derived inflammatory macrophages largely contributes to the transition to heart failure. The current review examines the ambivalent role of inflammation (mainly TNFα-related) and cardiac macrophages (Mφ) in pathophysiologies from non-infarction origin, focusing on the protective signaling processes. Our objective is to illustrate how harnessing this knowledge could pave the way for innovative therapeutics in patients with heart failure.

Cancer Chemotherapy-Induced Sinus Bradycardia: A Narrative Review of a Forgotten Adverse Effect of Cardiotoxicity

Cardiotoxicity is a common adverse effect of anticancer drugs (ACDs), including the so-called targeted drugs, and increases morbidity and mortality in patients with cancer. Attention has focused mainly on ACD-induced heart failure, myocardial ischemia, hypertension, thromboembolism, QT prolongation, and tachyarrhythmias. Yet, although an increasing number of ACDs can produce sinus bradycardia (SB), this proarrhythmic effect remains an underappreciated complication, probably because of its low incidence and severity since most patients are asymptomatic. However, SB merits our interest because its incidence increases with the aging of the population and cancer is an age-related disease and because SB represents a risk factor for QT prolongation. Indeed, several ACDs that produce SB also prolong the QT interval. We reviewed published reports on ACD-induced SB from January 1971 to November 2020 using the PubMed and EMBASE databases. Published reports from clinical trials, case reports, and recent reviews were considered. This review describes the associations between ACDs and SB, their clinical relevance, risk factors, and possible mechanisms of onset and treatment.

Níveis mais Baixos de Fetuína-A Sérica estão Associados a um Maior Risco de Mortalidade em Dez Anos em Pacientes com Infarto do Miocárdio por Supradesnivelamento do Segmento ST

Fundamento

A fetuína-A é um fator anti-inflamatório e anticalcificação envolvido no curso da doença arterial coronariana (DAC). Em alinhamento com essas funções, investigou-se a fetuína-A como marcador de risco cardiovascular em vários estudos. Porém, a associação entre a fetuína-A e o prognóstico dos pacientes com DAC ainda é controversa.

Objetivos

O presente estudo foi conduzido para identificar a associação entre o nível de fetuína-A sérica e doença cardiovascular (DCV) de longo prazo e a mortalidade global por infarto do agudo do miocárdio por supradesnivelamento do segmento ST (STEMI).

Métodos

Foram cadastrados no estudo cento e oitenta pacientes consecutivos com STEMI. A população do estudo foi dividida em subgrupos (mais baixo, ≤288 µg/ml; e mais alto, >288 µg/ml) de acordo com a mediana do nível de fetuína-A. Dados de acompanhamento clínico foram obtidos por contato telefônico anual com pacientes ou familiares. As causas das mortes também foram confirmadas pelo banco de dados de saúde nacional. P-valores bilaterais <0,05 foram considerados estatisticamente significativos.

Resultados

Durante um acompanhamento médio de 10 anos, foram registradas 71 mortes, das quais 62 foram devidas a DCV. Identificou-se um índice de mortalidade global e por DCV significativamente mais alto no grupo com nível de fetuína-A mais baixo que no grupo com nível de fetuína-A mais alto (44% versus 24%, p= 0,005; 48% versus 31%, p= 0,022, respectivamente). Nas análises de risco proporcionais por regressão de Cox, detectou-se que a fetuína-A era um preditor independente de mortalidade global e por DCV.

Conclusões

A baixa concentração de fetuína-A está associada ao prognóstico de longo prazo ruim pós-STEMI, independentemente de fatores de risco cardiovascular tradicionais. Nossos achados fortaleceram estudos prévios demonstrando consistentemente o papel determinante dos mediadores anti-inflamatórios em síndromes coronárias agudas.

Interleukin-17 upregulation participates in the pathogenesis of heart failure in mice via NF-κB-dependent suppression of SERCA2a and Cav1.2 expression

Interleukin-17 (IL-17), also called IL-17A, is an important regulator of cardiac diseases, but its role in calcium-related cardiac dysfunction remains to be explored. Thus, we investigated the influence of IL-17 on calcium handling process and its contribution to the development of heart failure. Mice were subjected to transaortic constriction (TAC) to induce heart failure. In these mice, the levels of IL-17 in the plasma and cardiac tissue were significantly increased compared with the sham group. In 77 heart failure patients, the plasma level of IL-17 was significantly higher than 49 non-failing subjects, and was negatively correlated with cardiac ejection fraction and fractional shortening. In IL-17 knockout mice, the shortening of isolated ventricular myocytes was increased compared with that in wild-type mice, which was accompanied by significantly increased amplitude of calcium transient and the upregulation of SERCA2a and Cav1.2. In cultured neonatal cardiac myocytes, treatment of with IL-17 (0.1, 1 ng/mL) concentration-dependently suppressed the amplitude of calcium transient and reduced the expression of SERCA2a and Cav1.2. Furthermore, IL-17 treatment increased the expression of the NF-κB subunits p50 and p65, whereas knockdown of p50 reversed the inhibitory effects of IL-17 on SERCA2a and Cav1.2 expression. In mice with TAC-induced mouse heart, IL-17 knockout restored the expression of SERCA2a and Cav1.2, increased the amplitude of calcium transient and cell shortening, and in turn improved cardiac function. In addition, IL-17 knockout attenuated cardiac hypertrophy with inhibition of calcium-related signaling pathway. In conclusion, upregulation of IL-17 impairs cardiac function through NF-κB-mediated disturbance of calcium handling and cardiac remodeling. Inhibition of IL-17 represents a potential therapeutic strategy for the treatment of heart failure.

Coronavirus and Cardiovascular Disease, Myocardial Injury, and Arrhythmia: JACC Focus Seminar

The cardiovascular system is affected broadly by severe acute respiratory syndrome coronavirus 2 infection. Both direct viral infection and indirect injury resulting from inflammation, endothelial activation, and microvascular thrombosis occur in the context of coronavirus disease 2019. What determines the extent of cardiovascular injury is the amount of viral inoculum, the magnitude of the host immune response, and the presence of co-morbidities. Myocardial injury occurs in approximately one-quarter of hospitalized patients and is associated with a greater need for mechanical ventilator support and higher hospital mortality. The central pathophysiology underlying cardiovascular injury is the interplay between virus binding to the angiotensin-converting enzyme 2 receptor and the impact this action has on the renin-angiotensin system, the body’s innate immune response, and the vascular response to cytokine production. The purpose of this review was to describe the mechanisms underlying cardiovascular injury, including that of thromboembolic disease and arrhythmia, and to discuss their clinical sequelae.

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The cardiovascular system is affected in diverse ways by severe acute respiratory syndrome coronavirus 2 infection (COVID-19).

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Myocardial injury can be detected in ∼25% of hospitalized patients with COVID-19 and is associated with an increased risk of mortality.

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Described mechanisms of myocardial injury in patients with COVID-19 include oxygen supply–demand imbalance, direct viral myocardial invasion, inflammation, coronary plaque rupture with acute myocardial infarction, microvascular thrombosis, and adrenergic stress.

COVID-19 for the Cardiologist: Basic Virology, Epidemiology, Cardiac Manifestations, and Potential Therapeutic Strategies

Coronavirus disease-2019 (COVID-19), a contagious disease caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), has reached pandemic status. As it spreads across the world, it has overwhelmed health care systems, strangled the global economy, and led to a devastating loss of life. Widespread efforts from regulators, clinicians, and scientists are driving a rapid expansion of knowledge of the SARS-CoV-2 virus and COVID-19. The authors review the most current data, with a focus on the basic understanding of the mechanism(s) of disease and translation to the clinical syndrome and potential therapeutics. The authors discuss the basic virology, epidemiology, clinical manifestation, multiorgan consequences, and outcomes. With a focus on cardiovascular complications, they propose several mechanisms of injury. The virology and potential mechanism of injury form the basis for a discussion of potential disease-modifying therapies.

[Myocardial injury associated with chronic hepatitis C: Clinical types and pathogenetic components]

Heart injury is one of the extrahepatic manifestations of chronic hepatitis C (CHC). The paper gives Russian and foreign authors' data on a relationship between CHC and myocardial injury. It discusses different pathogenetic components (the direct effect of the virus, immunological components), through which hepatitis C virus can induce myocarditis and cardiomyopathies in patients with CHC.

A synergistic protective effect of selenium and taurine against experimentally induced myocardial infarction in rats

This study investigated the protective effect of subacute pre-adminsitration of either selenium (Se), taurine (Tau), or both drugs in combination against experimentally induced myocardial infarction (MI) in rats and illustrates the possible mechanisms of action. While solely pre-administration of Se or Tau resulted in partial amelioration in all of the measured parameters in MI rats, concomitant administration of both drugs to MI rats significantly restored contractility function by increasing LVSP and decreasing LVEDP and significantly normalized serum levels of LDH, CK-MB and BNP and restored normal cardiac architecture. This concomitant treatment acted by increasing the activity of major antioxidant enzymes (SOD and GPx), decreasing the levels of inflammatory markers including TNF-α, IL-6 as well as levels of Bcl-2 and caspase-3 and downregulating mRNA levels of Bax and P53, markers of apoptosis. In conclusion, a combination of Se and Tau provides a new strategy to alleviate MI-induced cardiac dysfunction.

Identification and functional characterization of tumor necrosis factor receptor 1 (TNFR1) of grass carp (Ctenopharyngodon idella)

Tumor necrosis factor-alpha (TNF-α) exerts its regulatory effects by binding one of two TNF receptors, TNF-α receptor 1 (TNFR1) or TNFR2. In this study, we isolated and identified the cDNA sequence of grass carp TNFR1 (gcTNFR1). Similar to its homologs in other fish species, the putative protein of gcTNFR1 possessed an extracellular region containing three TNF homology domains, a transmembrane region and a cytoplasmic region with a conserved death domain. Consistent with the widespread expression of mammalian TNFR1, gcTNFR1 transcripts ubiquitously expressed in spleen, thymus, liver, heart, gill, intestine, brain and head kidney with the highest expression levels in head kidney. To reveal its inductive expression patterns in inflammatory response, effect of in vivo bacterial infection on gcTNFR1 gene expression was examined, showing a rapid increase of gcTNFR1 expression in head kidney, gill, liver and intestine, which is consistent with the role of TNF-α as an early response gene during immune challenges. To define the functional role of gcTNFR1, recombinant extracellular region of gcTNFR1 (rgcTNFR1) was prepared and used to perform in vitro binding assay, demonstrating its ability to interact with recombinant grass carp TNF-α (rgcTNF-α). Furthermore, to characterize the function of gcTNFR1 in affecting rgcTNF-α actions, the effect of overexpressing gcTNFR1 on rgcTNF-α-induced grass carp IL-1β (gcIL-1β) promoter activity was determined in COS7 cells. Results showed that gcTNFR1 was involved in the regulation of rgcTNF-α on gcIL-1β transcription. Consistently, rgcTNFR1 was effective in attenuating the effect of rgcTNF-α on IL-1β mRNA expression in grass carp head kidney leukocytes, providing evidence for the involvement of TNFR1 in TNF-α signaling in grass carp. These data facilitate a better understanding of TNF-α receptor signaling in grass carp.

Tumor Necrosis Factor Alpha Inhibits L-Type Ca(2+) Channels in Sensitized Guinea Pig Airway Smooth Muscle through ERK 1/2 Pathway

Tumor necrosis factor alpha (TNF-α) is a potent proinflammatory cytokine that plays a significant role in the pathogenesis of asthma by inducing hyperresponsiveness and airway remodeling. TNF-α diminishes the L-type voltage dependent Ca²⁺ channel (L-VDCC) current in cardiac myocytes, an observation that seems paradoxical. In guinea pig sensitized tracheas KCl responses were lower than in control tissues. Serum from sensitized animals (Ser-S) induced the same phenomenon. In tracheal myocytes from nonsensitized (NS) and sensitized (S) guinea pigs, an L-VDCC current (ICa) was observed and diminished by Ser-S. The same decrease was detected in NS myocytes incubated with TNF-α, pointing out that this cytokine might be present in Ser-S. We observed that a small-molecule inhibitor of TNF-α (SMI-TNF) and a TNF-α receptor 1 (TNFR1) antagonist (WP9QY) reversed ICa decrease induced by Ser-S in NS myocytes, confirming the former hypothesis. U0126 (a blocker of ERK 1/2 kinase) also reverted the decrease in ICa. Neither cycloheximide (a protein synthesis inhibitor) nor actinomycin D (a transcription inhibitor) showed any effect on the TNF-α-induced ICa reduction. We found that Ca_V1.2 and Ca_V1.3 mRNA and proteins were expressed in tracheal myocytes and that sensitization did not modify them. In cardiac myocytes, ERK 1/2 phosphorylates two sites of the L-VDCC, augmenting or decreasing ICa; we postulate that, in guinea pig tracheal smooth muscle, TNF-α diminishes ICa probably by phosphorylating the L-VDCC site that reduces its activity through the ERK1/2 MAP kinase pathway.

Fetuin-A is related to infarct size, left ventricular function and remodelling after acute STEMI

Objective

To investigate the relationship between plasma fetuin-A, an anti-inflammatory glycoprotein which might be involved in myocardial healing after acute infarction, and infarct size, left ventricular (LV) function and dimensions as well as the occurrence of adverse remodelling at 4 months after acute ST segment elevation myocardial infarction (STEMI).

Methods

In this single-centre prospective, observational study, 89 patients underwent cardiac MR within the first week and 4 months after mechanical reperfusion for first STEMI. Infarct size, LV function and dimensions were assessed at both time points. Fetuin-A levels were determined from blood samples drawn at a median of 49 h (IQR 30–59 h) after STEMI by an immunofluorescent assay.

Results

Fetuin-A levels (median 568 µg/mL, IQR 478–763 µg/mL) were significantly correlated with infarct size and LV ejection fraction at baseline and follow-up (all p<0.05). Moreover, fetuin-A was related to the increase in the end-diastolic volume index (r=−0.383, p<0.001). According to multivariate logistic regression analysis, fetuin-A concentrations (HR=0.17, 95% CI 0.03 to 0.89, p=0.036) besides the presence of late microvascular obstruction (HR=10.03, 95% CI 0.98 to 102.43, p=0.05) were significantly related to the occurrence of adverse LV remodelling at 4 months.

Conclusions

Circulating fetuin-A at day 2 after STEMI is related to acute and chronic infarct size, LV function and dimensions. In addition, it might be useful to identify patients at increased risk for adverse LV remodelling.

Tumor necrosis factor alpha stimulates p62 accumulation and enhances proteasome activity independently of ROS

Circulating TNF-α levels are elevated in a wide variety of cardiovascular pathologies including congestive heart failure (CHF). This cytokine is one of the leading mediators of the immune inflammatory response with widespread biological functions regulated by membrane receptors. The pathophysiological implication of the downstream effects of activating the TNF-α system in CHF appears to depend on its direct effects on the heart and endothelium. Evidence supporting the notion that circulating TNF-α promotes protein breakdown was initially obtained from studies utilizing transgenic animals overexpressing TNF-α, animals with experimental diseases that augment TNF-α and in animals treated with exogenous TNF-α. It was then demonstrated that TNF-α acts directly on cultured myotubes to stimulate catabolism; however, whether the effects are the same in the heart remains poorly understood. The present study shows that TNF-α treatment induces autophagy, but clearance through this pathway appears obstructed and, consequently, results in increased protein ubiquitination. Furthermore, prolonged TNF-α treatment enhanced E3 ubiquitin ligase expression but reduced activity of the proteasome. These results suggest that TNF-α induces sarcomeric dysfunction and remodeling by disrupting autophagy and elevating the degradation of myofibrillar proteins. Therefore, myocardial remodeling, as a consequence to reduced contractile proteins, contributes to contractile dysfunction, a symptom often observed in the end stages of CHF.

Regulatory RNAs and paracrine networks in the heart

Cardiac hypertrophy and fibrosis are two closely related adaptive response mechanisms of the myocardium to mechanical, metabolic, and genetic stress that finally contribute to the development of heart failure (HF). This relation is based on a dynamic interplay between many cell types including cardiomyocytes and fibroblasts during disease progression. Both cell types secrete a variety of growth factors, cytokines, and hormones that influence hypertrophic cardiomyocyte growth and fibrotic fibroblast activation in a paracrine and autocrine manner. It has become evident that, aside proteinous signals, microRNAs (miRNAs) and possible other RNA species such as long non-coding RNAs are potential players in such a cell-to-cell communication. By directly acting as paracrine signals or by modulating downstream intercellular signalling mediators, miRNAs can act as moderators of the intercellular crosstalk. These small regulators can potentially be secreted in a 'mircrine' fashion, so that miRNAs can be assumed as the message itself. This review will summarize the recent findings about the paracrine crosstalk between cardiac fibroblasts and cardiomyocytes and addresses how miRNAs may be involved in this interplay. It also highlights therapeutic strategies targeting factors of pathological communication for the treatment of HF.

The effects of tumor necrosis factor-alpha on systolic and diastolic function in rat ventricular myocytes

The proinflammatory cytokine tumor necrosis factor-alpha (TNF-α) is associated with myocardial dysfunction observed in sepsis and septic shock. There are two fundamental components to this dysfunction. (1) systolic dysfunction; and (2) diastolic dysfunction. The aim of these experiments was to determine if any aspect of whole-heart dysfunction could be explained by alterations to global intracellular calcium ([Ca²⁺]_i), contractility, and [Ca²⁺]_i handling, by TNF-α, at the level of the individual rat myocyte. We took an integrative approach to simultaneously measure [Ca²⁺]_i, contractility and sarcolemmal Ca fluxes using the Ca indicator fluo-3, video edge detection, and the perforated patch technique, respectively. All experiments were performed at 37°C. The effects of 50 ng/mL TNF-α were immediate and sustained. The amplitude of systolic [Ca²⁺]_i was reduced by 31% and systolic shortening by 19%. Diastolic [Ca²⁺]_i, myocyte length and relaxation rate were not affected, nor were the activity of the [Ca²⁺]_i removal mechanisms. The reduction in systolic [Ca²⁺]_i was associated with a 14% reduction in sarcoplasmic reticulum (SR) content and a 11% decrease in peak L-type Ca current (I_Ca-L). Ca influx was decreased by 7% associated with a more rapid I_Ca-L inactivation. These data show that at the level of the myocyte, TNF-α reduces SR Ca which underlies a reduction in systolic [Ca²⁺]_i and thence shortening. Although these findings correlate well with aspects of systolic myocardial dysfunction seen in sepsis, in this model, acutely, TNF-α does not appear to provide a cellular mechanism for sepsis-related diastolic myocardial dysfunction.

Usefulness of fetuin-A and C-reactive protein concentrations for prediction of outcome in acute coronary syndromes (from the French Registry of Acute ST-Elevation Non-ST-Elevation Myocardial Infarction [FAST-MI])

Fetuin-A is a ubiquitous anti-inflammatory glycoprotein that counteracts proinflammatory cytokine production. Previous studies have shown that low fetuin-A concentration is associated with cardiovascular death and may play an important role in the prognosis of patients with acute coronary syndromes (ACS). The purpose of this study was to assess in large cohort of patients admitted for ACS the prognostic value of fetuin-A adjusted for C-reactive protein value (CRP) and Global Registry of Acute Coronary Events (GRACE) risk score. Plasma fetuin-A and CRP concentrations were measured on day 3 in 754 consecutive patients with ACS (mean age 66 ± 14 years, 404 with ST-segment elevation and 350 without ST-segment elevation) included in the French Registry of Acute ST-Elevation or Non-ST-Elevation Myocardial Infarction (FAST-MI), and these data were correlated to 1-year mortality. Plasma fetuin-A and CRP concentrations at admission averaged 95 ± 27 and 12 ± 16 mg/L, respectively. Overall, 1-year cardiovascular mortality was 10% (28 in-hospital deaths and 51 deaths after discharge), 17% in patients with low fetuin-A (less than the first tertile), 18% with high CRP (higher than the third tertile), and 23% in patients with low fetuin associated with high CRP (p <0.01). In contrast, patients with neither low fetuin-A nor high CRP had a low mortality rate (5%). Multivariate analysis adjusted for GRACE risk score showed that low fetuin-A and high CRP concentration remained associated with outcomes (odds ratio 2.28, 95% confidence interval 1.20 to 4.33). In conclusion, fetuin-A combined with CRP level is associated with cardiovascular death in patients with ACS.

Cardiac intercellular communication: are myocytes and fibroblasts fair-weather friends?

The cardiac fibroblast (CF) has historically been thought of as a quiescent cell of the heart, passively maintaining the extracellular environment for the cardiomyocytes (CM), the functional cardiac cell type. The increasingly appreciated role of the CF, however, extends well beyond matrix production, governing many aspects of cardiac function including cardiac electrophysiology and contractility. Importantly, its contributions to cardiac pathophysiology and pathologic remodeling have created a shift in the field's focus from the CM to the CF as a therapeutic target in the treatment of cardiac diseases. In response to cardiac injury, the CF undergoes a pathologic phenotypic transition into a myofibroblast, characterized by contractile smooth muscle proteins and upregulation of collagens, matrix proteins, and adhesion molecules. Further, the myofibroblast upregulates expression and secretion of a variety of pro-inflammatory, profibrotic mediators, including cytokines, chemokines, and growth factors. These mediators act in both an autocrine fashion to further activate CFs, as well as in a paracrine manner on both CMs and circulating inflammatory cells to induce myocyte dysfunction and chronic inflammation, respectively. Together, cell-specific cytokine-induced effects exacerbate pathologic remodeling and progression to HF. A better understanding of this dynamic intercellular communication will lead to novel targets for the attenuation of cardiac remodeling. Current strategies aimed at targeting cytokines have been largely unsuccessful in clinical trials, lending insights into ways that such intercellular cross talk can be more effectively attenuated. This review will summarize the current knowledge regarding CF functions in the heart and will discuss the regulation and signaling behind CF-mediated cytokine production and function. We will then highlight clinical trials that have exploited cytokine cross talk in the treatment of heart failure and provide novel strategies currently under investigation that may more effectively target pathologic CF-CM communication for the treatment of cardiac disease. This review explores novel mechanisms to directly attenuate heart failure progression through inhibition of signaling downstream of pro-inflammatory cytokines that are elevated after cardiac injury.

The role of Ca2+/calmodulin-dependent protein kinase II and calcineurin in TNF-α-induced myocardial hypertrophy

We investigated whether Ca2+/calmodulin-dependent kinase II (CaMKII) and calcineurin (CaN) are involved in myocardial hypertrophy induced by tumor necrosis factor α (TNF-α). The cardiomyocytes of neonatal Wistar rats (1-2 days old) were cultured and stimulated by TNF-α (100 μg/L), and Ca2+ signal transduction was blocked by several antagonists, including BAPTA (4 µM), KN-93 (0.2 µM) and cyclosporin A (CsA, 0.2 µM). Protein content, protein synthesis, cardiomyocyte volumes, [Ca2+]i transients, CaMKIIδB and CaN were evaluated by the Lowry method, [³H]-leucine incorporation, a computerized image analysis system, a Till imaging system, and Western blot analysis, respectively. TNF-α induced a significant increase in protein content in a dose-dependent manner from 10 µg/L (53.56 µg protein/well) to 100 μg/L (72.18 µg protein/well), and in a time-dependent manner from 12 h (37.42 µg protein/well) to 72 h (42.81 µg protein/well). TNF-α (100 μg/L) significantly increased the amplitude of spontaneous [Ca2+]i transients, the total protein content, cell size, and [³H]-leucine incorporation in cultured cardiomyocytes, which was abolished by 4 µM BAPTA, an intracellular Ca2+ chelator. The increases in protein content, cell size and [³H]-leucine incorporation were abolished by 0.2 µM KN-93 or 0.2 µM CsA. TNF-α increased the expression of CaMKIIδB by 35.21% and that of CaN by 22.22% compared to control. These effects were abolished by 4 µM BAPTA, which itself had no effect. These results suggest that TNF-α induces increases in [Ca2+]i, CaMKIIδB and CaN and promotes cardiac hypertrophy. Therefore, we hypothesize that the Ca2+/CaMKII- and CaN-dependent signaling pathways are involved in myocardial hypertrophy induced by TNF-α.

Emerging role for TNF-α in erectile dysfunction

INTRODUCTION

A role for cytokines in the pathophysiology of erectile dysfunction (ED) has emerged. Cytokines induce genes that synthesize other peptides in the cytokine family and several mediators, such as prostanoids, leukotrienes, nitric oxide, bradykinin, reactive oxygen species, and platelet-activating factor, all of which can affect vascular function. Consistent with the fact that the cavernosal tissue is a complex extension of the vasculature, risk factors that affect the vasculature have been shown to affect cavernosal function as well. Accordingly, the penile tissue has been recognized as an early sentinel for atherosclerosis that underlies coronary artery disease and cardiovascular diseases (CVD).

AIM

To review the literature pertaining to the role of tumor necrosis factor-alpha (TNF-α) in ED.

METHODS

PubMed search for pertinent publications on the role of cytokines, particularly TNF-α, in CVD and ED.

MAIN OUTCOME MEASURES

Clinical and experimental evidence demonstrates that TNF-α may play a role in ED.

RESULTS

TNF-α has been shown to play an important role in CVD, mainly due to its direct effects on the vasculature. In addition, high levels of TNF-α were demonstrated in patients with ED. In this review, we present a short description of the physiology of erection and the cytokine network. We focus on vascular actions of TNF-α that support a role for this cytokine as a potential candidate in the pathophysiology of ED, particularly in the context of CVD. A brief overview of its discovery, mechanisms of synthesis, receptors, and its main actions on the systemic and penile vasculature is also presented.

CONCLUSIONS

Considering that ED results from a systemic arterial defect not only confined to the penile vasculature, implication of TNF-α in the pathophysiology of ED offers a humoral linking between CVD and ED.

Nitric oxide and calcium signaling regulate myocardial tumor necrosis factor-α expression and cardiac function in sepsis

Myocardial tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine, is a critical inducer of myocardial dysfunction in sepsis. The purpose of this review is to summarize the mechanisms through which TNF-alpha production is regulated in cardiomyocytes in response to lipopolysaccharide (LPS), a key pathogen-associated molecular pattern (PAMP) in sepsis. These mechanisms include Nox2-containing NAD(P)H oxidase, phospholipase C (PLC)gamma1, and Ca2+ signaling pathways. Activation of these pathways increases TNF-alpha expression via activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK). Conversely, activation of c-Jun NH2-terminal kinase 1 (JNK1) negatively regulates TNF-alpha production through inhibition of ERK1/2 and p38 MAPK activity. Interestingly, endothelial nitric oxide synthase (eNOS) promotes TNF-alpha expression by enhancing p38 MAPK activation, whereas neuronal NOS (nNOS) inhibits TNF-alpha production by reducing Ca2+-dependent ERK1/2 activity. Therefore, the JNK1 and nNOS inhibitory pathways represent a "brake" that limits myocardial TNF-alpha expression in sepsis. Further understanding of these signal transduction mechanisms may lead to novel pharmacological therapies in sepsis.

The effect of diazepam on myocardial function and coronary vascular tone after endotoxemia in the isolated rat heart model

OBJECTIVE AND DESIGN

Tumor necrosis factor alpha (TNF-α) has been implicated in the pathogenesis of cardiovascular disease and sepsis-associated cardiac dysfunction. Although initially described solely as a lipopolysaccharide (LPS)-induced macrophage product, evidence exists that cardiac myocytes themselves produce substantial amounts of TNF-α in response to ischemia as well as LPS. The use of phosphodiesterase inhibitors has been shown to decrease LPS-induced TNF-α elaboration. The aim of the present study was to determine the effect of diazepam (Type IV phosphodiesterase inhibitor) on (1) myocardial function and (2) coronary vascular flow after LPS-induced endotoxic shock in an isolated rat heart model.

MATERIALS AND METHODS

Endotoxemia was induced by intraperitoneal LPS administration in adult male Wistar rats. Hearts were isolated after 6 h and perfused in a working mode with oxygenated Krebs-Henseleit buffer at 37°C. Diazepam was mixed with Krebs-Henseleit buffer and administered (3.0 μg/ml) for 20 min.

RESULTS

LPS-treated hearts showed depressed cardiac function and reduced coronary flow. Myocardial functional parameters (LVDP, +dP/dt, -dP/dt, RPP) and coronary flow (ml/min) were significantly (p < 0.01) improved by diazepam administration.

CONCLUSIONS

These findings suggest that diazepam can salvage myocardial function and undo coronary vascular constriction in the endotoxemic rat heart. These findings are clinically relevant to the treatment of cardiovascular depression caused by endotoxic shock.

Plasma concentrations of TNF-alpha and its soluble receptors sTNFR1 and sTNFR2 in patients with coronary artery disease

Tumour necrosis factor alpha (TNF-alpha) is implicated in post-ischemic myocardial dysfunction. Two distinct TNF-alpha receptors are shed from cell membranes and circulate in plasma as soluble sTNFR1 and sTNFR2 proteins. The aim of the study was to establish factors associated with plasma concentrations of TNF-alpha and its receptors in patients with coronary artery disease (CAD). Since adenosine inhibits the expression of TNF-alpha, two functional polymorphisms in genes encoding enzymes participating in adenosine metabolism, i.e. AMP deaminase-1 (AMPD1, C34T) and adenosine deaminase (ADA, G22A), were analyzed. Plasma concentrations of TNF-alpha, sTNFR1, and sTNFR2 were measured using ELISA in 167 patients with CAD. Common factors significantly associated with higher TNF-alpha, sTNFR1, and sTNFR2 were lower glomerular filtration rate (GFR), older age, higher BNP, lower blood haemoglobin, and the presence of asthma or chronic obstructive pulmonary disease (COPD). Higher TNF-alpha and sTNFR1 concentrations were also associated with the presence of heart failure (HF), lower ejection and shortening fraction, the presence of diabetes or metabolic syndrome, lower serum HDL cholesterol, and higher uric acid. In multivariate analysis the common independent predictors of higher TNF-alpha, sTNFR1, and sTNFR2 were lower GFR, lower HDL cholesterol, higher BNP, and the presence of asthma or COPD. There were no associations between AMPD1 C34T or ADA G22A genotypes and TNF-alpha or its receptors. In conclusion, the concentrations of TNF-alpha, sTNFR1, and sTNFR2 reflect the impairment of cardiac and renal function in patients with CAD. Metabolic syndrome and diabetes are associated with higher plasma concentrations of TNF-alpha and its receptors.

AMP-activated protein kinase confers protection against TNF-{alpha}-induced cardiac cell death

AIMS

Although a substantial role for 5' adenosine monophosphate-activated protein kinase (AMPK) has been established in regulating cardiac metabolism, a less studied action of AMPK is its ability to prevent cardiac cell death. Using established AMPK activators like dexamethasone (DEX) or metformin (MET), the objective of the present study was to determine whether AMPK activation prevents tumour necrosis factor-alpha (TNF-alpha) induced apoptosis in adult rat ventricular cardiomyocytes.

METHODS AND RESULTS

Cardiomyocytes were incubated with DEX, MET, or TNF-alpha for varying durations (0-12 h). TNF-alpha-induced cell damage was evaluated by measuring caspase-3 activity and Hoechst staining. Protein and gene estimation techniques were employed to determine the mechanisms mediating the effects of AMPK activators on TNF-alpha-induced cardiomyocyte apoptosis. Incubation of myocytes with TNF-alpha for 8 h has increased caspase-3 activation and apoptotic cell death, an effect that was abrogated by DEX and MET. The beneficial effect of DEX and MET was associated with stimulation of AMPK, which led to a rapid and sustained increase in Bad phosphorylation. This event reduced the interaction between Bad and Bcl-xL, limiting cytochrome c release and caspase-3 activation. Addition of Compound C to inhibit AMPK reduced Bad phosphorylation and prevented the beneficial effects of AMPK against TNF-alpha-induced cytotoxicity.

CONCLUSION

Our data demonstrate that although DEX and MET are used as anti-inflammatory agents or insulin sensitizers, respectively, their common property to phosphorylate AMPK promotes cardiomyocyte cell survival through its regulation of Bad and the mitochondrial apoptotic mechanism.

Activation of the protective Survivor Activating Factor Enhancement (SAFE) pathway against reperfusion injury: Does it go beyond the RISK pathway?

Lethal reperfusion injury is now recognized as a major limitation of current reperfusion therapy by primary percutaneous coronary intervention for acute myocardial infarction. Interestingly, the heart itself is capable of activating an intrinsic protective signaling programme to limit cell death during reperfusion. Tumor necrosis factor alpha (TNFalpha) is a cytokine generally thought to contribute to myocardial dysfunction in ischemia/reperfusion or heart failure. We review evidence that TNFalpha can paradoxically initiate the activation of a novel protective pathway against reperfusion injuries that we have named the Survivor Activating Factor Enhancement (SAFE) pathway. This path requires the activation of the signal transducer and activator of transcription 3 (STAT-3) and it can successfully lessen cardiomyocyte death at the time of reperfusion, independently of the activation of the already well-described Reperfusion Injury Salvage Kinase (RISK) pathway (which includes activation of Akt and Erk 1/2). Emerging knowledge on this novel protective path is presented here with the aim of unravelling its interaction with the RISK pathway and its potential human application to protect against lethal reperfusion injury.

Ventricular K+ currents are reduced in mice with elevated levels of serum TNFalpha

In the present study mice were treated with tumor necrosis factor alpha (TNFalpha) for 6 weeks to determine if chronic TNFalpha treatment could produce serum levels of TNFalpha similar to what has been observed in disease states (heart failure, HIV) and to determine if these levels of TNFalpha alter ventricular K(+) currents. Mice chronically treated with TNFalpha and sham treated mice were utilized for experiments. Serum levels were measured with a Searchlight protein array. Patch-clamp techniques, real-time PCR and Western blot analysis were used to study K(+) current densities and K(+) channel expression. Results showed that serum concentrations of TNFalpha were significantly higher in TNFalpha treated mice compared to controls (control: 9.5+/-1.5 pg/ml, TNFalpha: 27.4+/-5.0 pg/ml; p<0.05) and comparable to serum TNFalpha levels observed in heart failure and HIV models. In ventricular myocytes from TNFalpha treated mice the outward K(+) currents I(to) and I(Kur) were significantly reduced (at +30 mV: I(to): control: 45.0+/-2.9 pA/pF, TNFalpha: 34.5+/-2.9 pA/pF; p<0.05; I(Kur): control 34.1+/-2.7 pA/pF, TNFalpha: 25.0+/-2.2 pA/pF; p<0.05). Expression studies revealed that ventricular mRNA and protein expression for the channels underlying I(to) and I(Kur) did not differ between the two groups. However, the recovery from inactivation for I(Kur) was significantly longer in TNFalpha treated mice. Overall, this study shows that pathologically relevant levels of serum TNFalpha modulate K(+) currents in mouse ventricle. These findings could help to explain the role of TNFalpha in the pathogenesis of cardiac arrhythmia.

Fetuin-A Is an Independent Predictor of Death after ST-Elevation Myocardial Infarction

Background: Fetuin-A inhibits inflammation and has a protective effect against myocardial ischemia. Its deficiency has been found to be associated with cardiovascular death in patients with end-stage renal failure disease. We investigated the association between plasma fetuin-A and clinical outcome after ST-elevation acute myocardial infarction (STEMI).

Methods: We measured fetuin-A in 284 consecutive patients with STEMI and correlated these data with the occurrence of death at 6 months (n = 25). We also measured fetuin-A in a control group and chose the 95th percentile as the cutoff to define abnormality.

Results: Patient mean (SD) age was 60 (14) years, and creatinine clearance was 83 (31) mL/min; 82% were men. Mean (SD) plasma fetuin-A concentrations at admission [188 (69) mg/L, P = 0.01] and at day 3 [163 (57) mg/L, P &lt;0.0001] were lower in patients than in controls [219 (39) mg/L; 95th percentile 140 mg/L]. Fetuin-A &lt;140 mg/L was observed in 20% of patients at admission vs 40% at day 3 (P &lt;0.001). Fetuin-A concentrations did not correlate with peak cardiac troponin values but did correlate inversely with C-reactive protein (CRP) and NT-pro-brain natriuretic peptide (NT-proBNP). Fetuin-A &lt;140 mg/L at admission (OR = 3.3, P = 0.03) and at day 3 (OR = 6.3, P = 0.002) was an independent correlate of death at 6 months, irrespective of NT-proBNP, CRP, or Controlled Abciximab and Device Investigation to Lower Late Angioplasty Complications (CADILLAC) risk score. Conversely, fetuin-A ≥140 mg/L was associated with an excellent survival rate [negative predictive value (NPV) = 97% overall], even in high-risk populations with CADILLAC risk score ≥6 (NPV = 90% in patients).

Conclusions: Fetuin-A is an important predictor of death at 6 months in STEMI patients independent of NT-proBNP, CRP, and CADILLAC risk score.

Adenosine and TNF-alpha exert similar inotropic effect on heart cultures, suggesting a cardioprotective mechanism against hypoxia

When cardiomyocytes were subjected to hypoxia, tumor necrosis factor-alpha (TNF-alpha; 3-50 ng/ml) or adenosine (1-100 microM), decreased hypoxic damage as was detected by lactate dehydrogenase (LDH) release, MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) absorbance, ROS (reactive oxygen species) measurement or desmin immunostaining. This cardioprotection was not prevented in TNF-alpha-treated cultures by 5-hydroxydecanoic acid (5-HD). Our aim was to elucidate whether adenosine and TNF-alpha mediate a similar protective mechanism against hypoxia in primary heart cultures and in H9c2 cardiomyocytes. Adenosine and TNF-alpha are known for their negative inotropic effects on the heart. We have suggested that deoxyglucose uptake reflects heart contractility in cell cultures; therefore, we assayed its accumulation under various conditions. Treatment for 20 min with adenosine, R-PIA [(-)-N(6)-phenylisopropyladenosine] (10 microM), or TNF-alpha reduced (3)H-deoxyglucose uptake in primary heart cultures and also in H9c2 cardiomyocytes by 30-50%. Isoproterenol accelerated (3)H-deoxyglucose uptake by 50%. Adenosine, R-PIA, or TNF-alpha attenuated the stimulatory effect of isoproterenol on (3)H-deoxyglucose uptake to control levels. Hypoxia reduced (3)H-deoxyglucose uptake by 50%, as in the treatment of the hypoxic cultures with TNF-alpha or adenosine. Glibenclamide (2 microM), 5-HD (300 microM), or diazoxide (50 microM) increased (3)H-deoxyglucose uptake by 50-80%. Adenosine (100 microM) and TNF-alpha (50 ng/ml) stimulated (86)Rb efflux. Glibenclamide attenuated this effect. We demonstrate that TNF-alpha, like adenosine, accelerated Ca(2+) uptake into the sarcoplasmic reticulum (SR) by 50-100% and therefore prevented cardiomyocyte Ca(2+) overload. Our findings further suggest that TNF-alpha, as well as adenosine, may mediate an adaptive effect in the heart by preventing Ca(2+) overload via activation of SR Ca-ATPase (SERCA(2)a).

Recent advances of TNF-α antagonists in rheumatoid arthritis and chronic heart failure

Tumor necrosis factor (TNF)-alpha has been thoroughly investigated and established as a pivotal component of the inflammatory cascade. This review encompasses the safety and efficacy of TNF antagonists in rheumatoid arthritis, the interplay between rheumatoid arthritis and heart failure, as well as presentation of the available preclinical and clinical data discussing the use of anti-TNF therapy in patients with chronic heart failure. There is well-documented evidence for the role of anti-TNF-alpha in rheumatoid arthritis, in contrast to the controversial role of anti-TNF-alpha in heart failure. In animal models and small-scale clinical trials, anti-TNF therapy showed some promise in treating chronic heart failure, whereas larger, multicenter, randomized, placebo-controlled clinical trials (i.e., RECOVER [Research into Etanercept Cytokine Antagonism in Ventricular Dysfunction] and RENAISSANCE [Randomized Etanercept North American Strategy to Study Antagonism of Cytokines]) failed to show a statistically significant difference in composite clinical function score for anti-TNF therapy versus placebo. Future investigation is needed to determine if individualized dosing of anti-TNF therapy is necessary and whether or not treating patients with earlier-stage disease will show a benefit.

TNF-alpha downregulates transient outward potassium current in rat ventricular myocytes through iNOS overexpression and oxidant species generation

Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine that has been implicated in the pathogenesis of heart failure. Prolongation of the action potential duration and downregulation of several K(+) currents might participate in the genesis of arrhythmias associated with chronic heart failure. Little information is available related to the mechanism by which TNF-alpha modulates cardiac K(+) channels. The present study analyzes the effect of TNF-alpha on the transient outward K(+) current (I(to)) in rat ventricular myocytes, using the whole cell patch-clamp technique. We found that TNF-alpha is able to induce a significant reduction of I(to) density, modifies its inactivation, and downregulates the Kv4.2 protein expression, while calcium current density is not affected. We have also demonstrated that the reduction of I(to) density induced by TNF-alpha was prevented by the selective inducible nitric oxide synthase (iNOS) inhibitor 1400-W, the protein synthesis inhibitor cycloheximide, the antioxidant tocopherol, and the superoxide dismutase mimetic manganese(III) tetrakis (4-benzoic acid) porphyrin. In addition, a reduced I(to) density was recorded in ventricular myocytes exposed to peroxynitrite, supporting a possible participation of this oxidant in the effects of TNF-alpha on I(to). We conclude that TNF-alpha exposure, through iNOS induction and generation of oxidant species, promotes electrophysiological changes (decreased I(to) and action potential duration prolongation) in rat ventricular myocytes, providing new insights into how cytokines modulate K(+) channels in the heart.

Tumor necrosis factor-alpha alters calcium handling and increases arrhythmogenesis of pulmonary vein cardiomyocytes

Inflammation and abnormal calcium homeostasis play important roles in atrial fibrillation. Tumor necrosis factor-alpha (TNFalpha), a proinflammatory cytokine, can induce cardiac arrhythmias. Pulmonary veins (PVs) are critical in initiating paroxysmal atrial fibrillation. This study was designed to investigate whether TNFalpha may change the calcium handling and arrhythmogenic activity of PV cardiomyocytes. We used whole-cell patch clamp and indo-1 fluorimetric ratio technique to investigate the action potentials, ionic currents and intracellular calcium in isolated rabbit single PV cardiomyocytes with and without (control) incubation with TNFalpha (25 ng/ml) for 7-10 h. The expression of sarcoplasmic reticulum ATPase in the control and TNFalpha-treated PV cardiomyocytes was evaluated by confocal micrographs and Western blot. We found that the spontaneous beating rates were similar between the control (n=45) and TNFalpha-treated (n=28) PV cardiomyocytes. Compared with the control PV cardiomyocytes, the TNFalpha-treated PV cardiomyocytes had significantly a larger amplitude of the delayed afterdepolarizations (6.0+/-1.7 vs. 2.6+/-0.8 mV, P<0.05), smaller L-type calcium currents, larger transient inward currents, larger Na(+)-Ca(2+) exchanger currents, a smaller intracellular calcium transient, smaller sarcoplasmic reticulum calcium content, larger diastolic intracellular calcium, a longer decay portion of the calcium transient (Tau), and a decreased sarcoplasmic reticulum ATPase expression. In conclusion, TNFalpha can increase the PV arrhythmogenicity and induce an abnormal calcium homeostasis, thereby causing inflammation-related atrial fibrillation.

Ligustrazine attenuates acute myocardium injury after thermal trauma

This study was designed to investigate the effects of ligustrazine on burn-induced myocardiac injury as well as TNF-alpha levels in severely burned rats. Sprague-Dawley rats were divided into four groups: (1) sham group, rats who underwent sham burn; (2) fluid-resuscitated sham group (FRsham), rats who underwent sham burn, and lactated Ringer's solution for resuscitation; (3) control group, rats given third-degree burns over 30% total body surface area (TBSA) and lactated Ringer's solution for resuscitation; (4) ligustrazine group, rats given burn and lactated Ringer's solution with ligustrazine inside for resuscitation. Myocardial injury was assessed at 6h after burn by detecting serum levels of creatine kinase MB fraction (CK-MB) and lactate dehydrogenase (LDH), as well as water content, histological score, and ultrastructure change of cardiac tissue. In addition, myocardium ATP content was analyzed. Enzyme-linked immunosorbent assay (ELISA) was used to examine cardiac tumor necrosis factor-alpha (TNF-alpha) levels. The results showed that burn trauma resulted in the increasing serum LDH and CK-MB, elevated myocardial water content, aggravated myocardial histological and ultrastructural lesions, increased myocardium ATP, and serum TNF-alpha. Ligustrazine 10mg/kg iv markedly inhibited increases in serum CK-MB and LDH, reduced myocardial water content from 76.91+/-0.19% in control group to 75.40+/-0.57%, significantly decreased the histologic scores of myocardium, and mollified the ultrastructural damage in cardiac myocytes. Ligustrazine significantly attenuated elevations in serum TNF-alpha level and myocardial ATP quantity. Therefore, our results demonstrate that ligustrazine exhibits significant protective effects on burn-induced myocardial injury via inhibiting the release of TNF-alpha and improving utilization of ATP.

Effect of tumor necrosis factor α on electrically induced calcium transients elicited in C2C12 skeletal myotubes

Diseases involving chronic inflammation can lead to prolonged exposure of skeletal muscle to inflammatory cytokines such as tumor necrosis factor alpha (TNFalpha), which may contribute to the skeletal muscle weakness seen in these conditions. In this study we examined the effect of a prolonged exposure to TNFalpha on intracellular Ca(2+) transients elicited in skeletal C(2)C(12) myotubes. A 48-h exposure to TNFalpha (10 ng/mL) significantly reduced the peaks, time to peak, and rate of Ca(2+) decay of electrically induced Ca(2+) transients elicited in C(2)C(12) skeletal myotubes. TNFalpha exposure had no significant effect on the resting Ca(2+) levels. The results of this study indicate that prolonged exposure to TNFalpha decreases sarcoplasmic reticulum Ca(2+) release in cultured skeletal muscle cells. This altered Ca(2+) release could contribute to the muscle weakness found in conditions involving chronic inflammation.

Glucocorticoids Alter the Balance Between Pro- and Anti-inflammatory Mediators in the Myocardium in a Porcine Model of Brain Death

BACKGROUND

Cardiac dysfunction after brain death (BD) limits donors for cardiac transplantation. Glucocorticoids ameliorate brain death-induced donor heart dysfunction. We hypothesized that glucocorticoid therapy alleviates myocardial depression through altering the balance between pro- and anti-inflammatory mediators via the nuclear factor-kappaB (NF-kappaB)/inhibitor of kappaB-alpha (IkappaBalpha) pathway and/or by preserving beta-adrenergic receptor (betaAR) signaling in the heart.

METHODS

Crossbred pigs (25 to 35 kg) were randomly assigned to the following groups (n = 5/treatment): sham (Group 1); BD (Group 2); and BD with glucocorticoids (30 mg/kg methylprednisolone), either 2 hours before (Group 3) or 1 hour after BD (Group 4). Tumor necrosis factor-alpha (TNF-alpha) levels were measured in plasma at baseline and 1 hour and 6 hours after BD. Protein levels were measured in left ventricular homogenates procured 6 hours after BD.

RESULTS

Pro-inflammatory proteins (TNF-alpha) and interleukin-6 were lower in Group 3 and Group 4 compared with Group 2 at 6 hours after BD (p < 0.01). Intracellular adhesion molecule-1 was also lower in Group 4 compared with Group 2 (p = 0.001). Interleukin-10, an anti-inflammatory mediator, was lower in Group 4 than in Group 2 (p < 0.001), but not different between Groups 2 and 3. At 6 hours after BD, neither NF-kappaB activity nor basal adenylate cyclase activity differed between Groups 3 and 4 compared with Group 2.

CONCLUSIONS

Glucocorticoids maintained myocardial function and shifted the balance of pro- and anti-inflammatory mediators after BD. The mechanisms by which glucocorticoids preserve myocardial function, however, do not appear to involve the NF-kappaB pathway or betaAR signaling.

Effects of carvedilol on M2 receptors and cholinesterase-positive nerves in adriamycin-induced rat failing heart

Heart failure is correlated with attenuation of parasympathetic nervous function and enhanced sympathetic activity. Carvedilol, a third-generation beta-blocker, may improve the prognosis of heart failure better than selective beta(1)-blockers. Not all of its effects, however, can be explained by direct actions on the sympathetic nervous system. This study was therefore performed to investigate the possible alterations of muscarinic cholinergic (M)(2) receptors and cholinesterase-positive nerves in different regions of the adriamycin-induced failing rat heart, and the potential effects of carvedilol on these M(2) receptors and cholinesterase-positive nerves. Karnovsky-Roots histochemical staining combined with point counting methods, and immunochemical streptavidin-biotin complex staining and image analysis were used to test the distribution of cholinesterase-positive nerves and the expression of M(2) receptors, respectively. Our results show that the cholinesterase-positive nerve system was downregulated in the adriamycin-induced failing heart group, while the density of M(2) receptors was increased in the carvedilol 3- and 10-mg/kg body weight groups, especially in the endocardial tissues of the left-ventricular free wall. It is concluded that upregulation of M(2) receptors may be one of the potential mechanisms by which carvedilol exert its action on heart failure.

TNF-alpha-mediated cardiomyocyte apoptosis involves caspase-12 and calpain

Following ischemia-reperfusion, there is a sustained increase of TNF-alpha both locally in the heart as well as in circulating levels in blood. While TNF-alpha has been implicated in cardiomyocyte apoptosis which occurs in several cardiomyopathies, the molecular pathways by which TNF-alpha induces apoptosis in these cells are not fully elucidated. We investigated the role of the two families of cysteine proteases, caspases and calpains, which are known to participate in apoptotic cell death. The effect of the highly specific calpain inhibitor, Z-LLY-fmk, and the caspase pathways involved in TNF-alpha-mediated apoptosis of the HL-1 cardiomyocyte cell line were examined. Activation of the downstream caspase-3, and the cleavage of poly ADP-ribose polymerase (PARP) were observed in a time-dependent manner upon treatment with TNF-alpha. Caspase-12, but not caspase-9, was activated in response to TNF-stimulation, indicating that an endoplasmic reticulum (ER)/calcium-dependent pathway may be involved. In HL-1 cardiomyocytes, TNF-alpha-induced apoptosis appears to be mediated by calpain as apoptotic changes were abrogated in the presence of the highly specific calpain inhibitor, Z-LLY-fmk. In conclusion, our results suggest that TNF-alpha-mediated apoptosis in HL-1 cardiomyocytes follows the caspase-12 apoptotic pathway that involves calpain.

Tumor necrosis factor-alpha inhibits the cardiac delayed rectifier K current via the asphingomyelin pathway

Tumor necrosis factor-alpha (TNF-alpha) affects contractility and ionic currents in the heart. However, the electrophysiological effects, especially on delayed rectifier K currents (IK), have not yet been fully elucidated. We examined the effects of TNF-alpha on IK. Using a voltage-clamp method, IK was measured in guinea pig ventricular myocytes in the basal state and after pharmacological intervention. To specify the site of the action of TNF-alpha, the myocytes were incubated with pertussis toxin or N-oleoylethanolamine, a ceramidase inhibitor, and IK was measured. TNF-alpha suppressed IK when it was enhanced by isoproterenol, histamine or forskolin but not in the basal state or when IK was augmented by an internal application of cyclic AMP. Both pre-incubation with pertussis toxin and N-oleoylethanolamine abolished the inhibitory action of TNF-alpha on isoproterenol-augmented IK. TNF-alpha inhibits IK, mainly IKs, when it is augmented by PKA as a result of the generation of sphingosine.

Cytokines and cardiovascular disease

The role of cytokines in the pathogenesis of cardiovascular disease is increasingly evident since the identification of immune/inflammatory mechanisms in atherosclerosis and heart failure. In this review, we describe how innate and adaptive immune cascades trigger the release of cytokines and chemokines, resulting in the initiation and progression of atherosclerosis. We discuss how cytokines have direct and indirect effects on myocardial function. These include myocardial depressant effects of nitric oxide (NO) synthase-generated NO, as well as the biochemical effects of cytokine-stimulated arachidonic acid metabolites on cardiomyocytes. Cytokine influences on myocardial function are time-, concentration-, and subtype-specific. We provide a comprehensive review of these cytokine-mediated immune and inflammatory cascades implicated in the most common forms of cardiovascular disease.

TNF and congestive heart failure: therapeutic possibilities

TNF-alpha is a cytokine that may play a role in the pathogenesis of heart failure. In patients with heart failure, increased levels of TNF-alpha were observed that were high enough to reduce cardiac contractility in vitro. The mortality of heart failure patients increases with higher levels of TNF-alpha. For these reasons, inhibition of TNF-alpha appears to be a valid target for the improvement of heart failure therapy beyond the current practice of inhibiting neurohormonal activation with beta-blockade, angiotensin-converting enzyme (ACE) inhibition and aldosterone antagonism. However, whilst this strategy (using soluble TNF receptor or TNF antibodies) was successful in smaller short-term studies, larger longer-term studies have not revealed any beneficial effect of this therapy (RENAISSANCE, RECOVER, RENEWAL, ATTACH). In contrast, the mortality tended to be higher in the treated groups giving rise to questions about the overall strategy. The reasons for this failure of the clinical studies to show a longer-term benefit from TNF-alpha inhibitors are unclear, but they may include an error of the general concept, individual adverse effects of the agents used for the studies, incorrect dosage and the fact that the current therapy of heart failure with beta-blockade, ACE inhibitors and aldosterone antagonists cannot be further improved by additional blockade of neurohormones or cytokines.

SEX DIFFERENCES IN THE MYOCARDIAL INFLAMMATORY RESPONSE TO ACUTE INJURY

Hemorrhage, trauma, ischemia/reperfusion, burn, and sepsis each lead to cardiac dysfunction. These insults lead to an inflammatory cascade, which plays an important role in this process. Gender has been shown to influence the inflammatory response, as well as outcomes after acute injury. The mechanisms by which gender affects the inflammatory response to and the outcome of acute injury are being actively investigated. We searched PubMed for articles in the English language by using the search words sex, gender, estrogen, testosterone, inflammation, acute injury, ischemia reperfusion, sepsis, trauma, and burns. These were used in various combinations. We read the abstracts of the relevant titles to confirm their relevance, and the full articles were then extracted. References from extracted articles were checked for any additional relevant articles. This review will examine evidence for gender differences in the outcome to acute injury, explain the myocardial inflammatory response to acute injury, and elucidate the various mechanisms by which gender affects the myocardial response to acute injury.

Cytokine-Induced Modulation of Cardiac Function

Cytokines act in an autocrine and/or paracrine fashion to induce a diverse variety of biological responses. Several cardiac diseases are associated with cytokine activation, and such activation significantly influences several physiologic parameters, including cardiac mechanical function. This review summarizes the current concepts regarding the modulation of myocardial function by cytokines and provides rationale for the sometimes-conflicting results in the literature regarding underlying mechanisms and patterns of dysfunction. Although traditionally considered cardiodepressant mediators, contractile responses are complex and bimodal, with an early response (within minutes) of variable direction, stimulatory or depressant, depending on the ambient physiologic milieu and relative contributions of the underlying signaling pathways that are activated. These pathways include sphingomyelinase-, nitric oxide (NO)-, and phospholipase A2-dependent signaling with resultant combined effects on contraction and the Ca2+ transient. This is subsequently followed by a profoundly cardiodepressant late response lasting hours to days, depending on the production of secondary mediators and the combined influence of NO generated from inducible NO synthase, reactive oxygen species, and alterations in beta-adrenergic receptor signaling. The interrelationships between these pathways and the time-dependence of their activation are important considerations in the evaluation of cytokine-dependent dysfunction during both acute cardiac injury and chronic cardiac pathologies.

Effect of Isoproterenol on the Cardiac Troponin I Degradation and Release during Early TNFα-Induced Ventricular Dysfunction in Isolated Rabbit Heart

We studied the consequences of an early phase of TNFalpha-induced LV dysfunction and of its treatment by isoproterenol on an isolated rabbit heart preparation. Two dosages of TNFalpha (2 and 4 microg) were infused, followed by isoproterenol (ISO), infused by increasing concentrations from 10 to 10 M. Left ventricular developed pressure (DP) was recorded. Creatine kinase (CKtot) and cardiac Troponin I (cTnI) were measured in the effluent perfusate. An anatomic score was calculated by histologic examination of the hearts while a structural analysis of cTnI was done. TNFalpha induced a dose-dependent decrease in DP (-43 +/- 18% for 4 microg) without change in coronary vascular resistances, which was not followed by biochemical or structural abnormalities. TNFalpha reduced the maximum effect (Emax) of ISO on DP (mean DeltaDPmaxISO = -40% for 4 microg) without change in the concentration leading to half Emax (ED50ISO). ISO treatment of TNFalpha (4 microg)-induced LV dysfunction resulted in a selective release of cTnI, myocardial tissue contraction bands, and a significant proteolysis of cTnI. Within the limits of the model, the myocardial injury reported during severe sepsis would not be related to an early cytotoxic effect of TNFalpha but could be attributed to an enhancement of the effects of isoproterenol by TNFalpha.

Inflammatory Cytokines and Postmyocardial Infarction Remodeling

Inflammatory response and cytokine elaboration are particularly active after myocardial infarction and contribute to cardiac remodeling and eventual host outcome. The triggers of cytokine release in the acute postinfarction period include mechanical deformation, ischemic stimulus, reactive oxygen species (ROS), and cytokine self-amplification pathways. Acutely, the elaboration of tumor necrosis factor, IL-1 and IL-6, transforming growth factor families of cytokines, contribute to survival or deaths of myocytes, modulation of cardiac contractility, alterations of vascular endothelium, and recruitment of additional circulating cells of inflammation to the injured myocardium. This leads to further local oxidative stress and remodeling but also initiates the processes of wound healing. Chronically, sustained presence of cytokines leads to myocyte phenotype transition and activation of matrix metalloproteinases that modifies interstitial matrix, augmenting further the remodeling process. This in turn alters the local collagen composition and also the integrins that constitute the interface between myocytes and the matrix. These processes ultimately, when favorable, pave the way for angiogenesis and cellular regeneration. Thus, the insightful modulation of cytokines through current and future therapies could promote improved healing and cardiac remodeling postmyocardial infarction.