Differential modulation of cytokine production by drugs: implications for therapy in heart failure

Novel Treatments of Hypertrophic Cardiomyopathy in GDMT for Heart Failure: A State-of-art Review

This state-of-the-art review discuss the available evidence on the use of novel treatments of hypertrophic cardiomyopathy such as omecamtiv mecarbil, EMD-57033, levosimendan, pimobendan, and mavacamten for the treatment of heart failure (HF) in the context of guideline-directed medical therapy (GDMT). The paper provides a detailed overview of these agents' mechanisms of action, potential benefits and limitations, and their effects on clinical outcomes. The review also evaluates the efficacy of the novel treatments in comparison to traditional medications such as digoxin. Finally, we seek to provide insight and guidance to clinicians and researchers in the management of HF patients.

Management of inflammation in cardiovascular diseases

Cardiovascular disease is the leading cause of morbidity and mortality world-wide. Recently, the role of inflammation in the progression of diseases has significantly attracted considerable attention. In addition, various comorbidities, including diabetes, obesity, etc. exacerbate inflammation in the cardiovascular system, which ultimately leads to heart failure. Furthermore, cytokines released from specialized immune cells are key mediators of cardiac inflammation. Here, in this review article, we focused on the role of selected immune cells and cytokines (both pro-inflammatory and anti-inflammatory) in the regulation of cardiac inflammation and ultimately in cardiovascular diseases. While IL-1β, IL-6, TNFα, and IFNγ are associated with cardiac inflammation; IL-10, TGFβ, etc. are associated with resolution of inflammation and cardiac repair. IL-10 reduces cardiovascular inflammation and protects the cardiovascular system via interaction with SMAD2, p53, HuR, miR-375 and miR-21 pathway. In addition, we also highlighted recent advancements in the management of cardiac inflammation, including clinical trials of anti-inflammatory molecules to alleviate cardiovascular diseases.

Sildenafil Reduces Expression and Release of IL-6 and IL-8 Induced by Reactive Oxygen Species in Systemic Sclerosis Fibroblasts

Oxidative stress linked to vascular damage plays an important role in the pathogenesis of systemic sclerosis (SSc). Indeed, vascular damage at nailfold capillaroscopy in patients with Raynaud's Phenomenon (RP) is a major risk factor for the development of SSc together with the presence of specific autoantiobodies. Here, we investigated the effects of the phosphodiesterase type 5 inhibitor (PDE5i) sildenafil, currently used in the management of RP, in modulating the proinflammatory response of dermal fibroblasts to oxidative stress in vitro. Human fibroblasts isolated from SSc patients and healthy controls were exposed to exogenous reactive oxygen species (ROS) (100 µM H2O2), in the presence or absence of sildenafil (1 µM). Treatment with sildenafil significantly reduced dermal fibroblast gene expression and cellular release of IL-6, known to play a central role in the pathogenesis of tissue damage in SSc and IL-8, directly induced by ROS. This reduction was associated with suppression of STAT3-, ERK-, NF-κB-, and PKB/AKT-dependent pathways. Our findings support the notion that the employment of PDE5i in the management of RP may be explored for its efficacy in modulating the oxidative stress-induced proinflammatory activation of dermal fibroblasts in vivo and may ultimately aid in the prevention of tissue damage caused by SSc.

A review of the pharmacology and clinical uses of pimobendan

OBJECTIVE

To review the pharmacology, research developments, and clinical uses of pimobendan

DATA SOURCES

Original research articles and clinical studies from 1984 to August 2011.

VETERINARY DATA SYNTHESIS

Pimobendan is approved for use in dogs for the treatment of congestive heart failure (CHF) secondary to chronic valvular heart disease (CVHD) and dilated cardiomyopathy (DCM). Expert-based veterinary guidelines recommend the use of pimobendan in the management of acute, hospital-based therapy for patients with CHF attributable to CVHD.

CONCLUSIONS

The use of pimobendan, an inodilator with phosphodiesterase 3 (PDE3) inhibitory and calcium-sensitizing properties, is regarded as a component of the standard of care in the management of dogs with CHF secondary to both DCM and CVHD. Further studies are warranted to confirm the safety and efficacy of pimobendan for the off-label use of this drug in asymptomatic CVHD, pulmonary arterial hypertension, asymptomatic myocardial diseases, CHF from all other causes and in cats with CHF.

Serial circulating concentrations of C-reactive protein, interleukin (IL)-4, and IL-6 in patients with acute left heart decompensation

BACKGROUND

Interleukin (IL)-6 has recently been shown to have negative inotropic effects, and several studies have reported increases in circulating concentrations of this cytokine in patients with depressed left ventricular ejection fraction and chronic left heart failure. However, most previous clinical studies have measured cytokines in compensated chronic heart failure.

HYPOTHESIS

The purpose of this study was to examine the temporal evolution of circulating concentrations of C-reactive protein (CRP) and cytokines in patients with cardiomyopathy and acute cardiac decompensation, free of infection and unstable angina.

METHODS

The time course of circulating concentrations of CRP, an anti-inflammatory cytokine interleukin (IL)-4, and a proinflammatory cytokine IL-6 were studied in eight patients with cardiomyopathy and acute cardiac decompensation in the absence of infection or unstable angina. Control samples were obtained from eight age-matched asymptomatic subjects.

RESULTS

Increased circulating concentrations of CRP (2.6 +/- 0.8 mg/dl), IL-4 (164.6 + 36.5 pg/ml), and IL-6 (17.1 +/- 5.1 pg/ml) were found in all eight patients during acute cardiac decompensation; these values decreased significantly with the resolution of symptoms of cardiac decompensation (0.5 +/- 0.1 mg/dl, 77.8 +/- 23.6 pg/ml, 2.3 +/- 0.1 pg/ml, respectively, p < 0.05 for both). There was a significant correlation between peak CRP and peak IL-6 (p < 0.05).

CONCLUSIONS

In patients with acute left heart decompensation in the absence of infection or coronary events, CRP, IL-4, and IL-6 increased and returned toward normal levels as the symptoms of heart failure resolved. Since the changes in concentrations of CRP, IL-4, and IL-6 in patients with heart failure are dynamic, the distinction between compensated and decompensated state is important when discussing the significance of acute reactive proteins or cytokines in the pathogenesis of heart failure.

Anti-tumour necrosis factor-alpha therapy in heart failure: future directions

The elevated level of tumour necrosis factor-alpha (TNF-alpha) in patients with heart failure has triggered interest in investigating the role of TNF-alpha in the pathogenesis of heart failure. Both clinical and experimental evidence has suggested that high levels of TNF-alpha occur in heart failure and lead to progression of left ventricular dysfunction. In addition, it has been documented that inhibition of TNF-alpha reverses its deleterious effects in heart failure. A number of clinical trials have been initiated to investigate the effect of anti-TNF-alpha therapy in patients with heart failure. The discouraging results of recent clinical trials of anti-TNF-alpha therapy in patients with heart failure have raised a number of questions about the role of TNF-alpha in heart failure. The present review critically analyzes the reasons of failure of anti-TNF-alpha therapy in heart failure. Moreover the potential approaches for the development of new anti-TNF-alpha therapy has been discussed which may open new vista of the management of heart failure.

Nutritional strategy in the management of heart failure in adults

The incidence of congestive heart failure (CHF) is increasing in Westernized countries, and patients with CHF experience poor quality of life (functional impairment, high hospitalization rate and high mortality). Malnutrition occurring during the course of CHF is referred to as cardiac cachexia and is associated with higher mortality independent of the severity of CHF. Cardiac cachexia involving a loss of more than 10% of lean body mass can clinically be defined as a bodyweight loss of 7.5% of previous dry bodyweight in a period longer than 6 months. The energy requirements of patients with CHF, whether cachectic or not, are not noticeably modified since the increase in resting energy expenditure is compensated by a decrease in physical activity energy expenditure. Malnutrition in CHF has been ascribed to neurohormonal alterations, i.e. anabolic/catabolic imbalance and increased cytokine release. Anorexia may occur, particularly during acute decompensation of CHF. Function is impaired in CHF, because of exertional dyspnea and changes in skeletal muscle. Decreased exercise endurance seems to be related to decreased mitochondrial oxidative capacities and atrophy of type 1 fibers, which are attributed to alteration in muscle perfusion and are partially reversible by training. Malnutrition could also impair muscle function, because of decreased muscle mass and strength associated with decreased glycolytic capacities and atrophy of type 2a and 2b fibres. With respect to the putative mechanisms of cardiac cachexia, anabolic therapy (hormones or nutrients) and anticytokine therapy have been proposed, but trials are scarce and often inconclusive. In surgical patients with CHF, perioperative (pre- and postoperative) nutritional support has been shown to be effective in reducing the mortality rate. Long term nutritional supplementation trials in patients with CHF and cachexia are thus required to establish recommendations for the nutritional management of patients with CHF.

Myocardial IL-6 regulation by neurohormones--an in vitro superfusion study

BACKGROUND

Interleukin-6 (IL-6) is expressed in the myocardium and has been implicated in cell proliferation, negative inotropic effects and myocardial hypertrophy. To determine whether myocardial IL-6 is modified by neurohumoral and immunoregulatory stimuli, we studied the effects of lipopolysaccharide (LPS), corticosterone (CS), isoproterenol and angiotensin II on myocardial IL-6 secretion in superfused myocardium.

METHODS

Slices of rat left ventricular myocardium were superfused in 80 microl chambers for up to 5h. LPS (1, 50, and 100 microg/ml), CS (10(-7), 10(-6), and 10(-5)M, DSMO as vehicle), isoproterenol (10(-6), 10(-7), and 10(-8)M) and angiotensin II (10(-5), 10(-7), and 10(-9)M) were added to the culture medium at hour 2. IL-6 was measured in the perfusate by ELISA.

RESULTS

Physiological corticosterone concentrations (10(-7)M) resulted in an increase in IL-6 concentration (142%) while high doses of steroid decreased IL-6 significantly (CS 10(-6)M: 88+/-14%,p<.05; CS 10(-5): 91+/-9%,p<.05) after 5h. Left ventricular IL-6 secretion was significantly stimulated by LPS 50 microg/ml (3262+/-1684% vs. CTRL: 116+/-34%, p<.01). Isoproterenol treatment increased in IL-6 secretion compared to controls with and without CS, while angiotensin II reduced IL-6 concentration only in combination with CS.

CONCLUSION

Myocardial IL-6 secretion is modulated by physiological concentrations of corticosterone or angiotensin II and can be induced by LPS or isoproterenol, indicating a tight regulation of this cytokine. Suppression of cytokine expression within the heart might be a potential therapeutic goal in the treatment of various cardiovascular diseases.

Effects of pimobendan on adverse cardiac events and physical activities in patients with mild to moderate chronic heart failure: the effects of pimobendan on chronic heart failure study (EPOCH study)

The long-term beneficial effects of pimobendan in the treatment of chronic heart failure (CHF) have not been established, so the present trial compared pimobendan (1.25 or 2.5mg twice daily) vs placebo in 306 patients with stable New York Heart Association class IIm or III CHF, and a radionuclide or echocardiographic left ventricular ejection fraction (LVEF) < or =45% despite optimal treatment with conventional therapy, for up to 52 weeks in a double-blind protocol. At the end of the 52 weeks of treatment, combined adverse cardiac events had occurred in 19 patients in the pimobendan group (15.9%) vs 33 patients in the placebo group (26.3%). The cumulative incidence of combined adverse cardiac events was 45% lower (95% confidence interval of hazard ratio: 0.31-0.97, log-rank test: p=0.035) in the pimobendan group than in the placebo group. Death and hospitalization for cardiac causes occurred in 12 patients in the pimobendan group (10.1%), vs 19 patients in the placebo group (15.3%), but without significant difference. Treatment with pimobendan also increased the mean Specific Activity Scale score from 4.39+/-0.12 at baseline to 4.68+/-0.15 at 52 weeks (p<0.05). In conclusion, long-term treatment with pimobendan significantly lowered morbidity and improved the physical activity of patients with mild to moderate CHF.

Inhibition of cyclic-3',5'-nucleotide phosphodiesterase abrogates the synergism of hypoxia with lipopolysaccharide in the induction of macrophage TNF-alpha production

BACKGROUND

Local tumor necrosis factor (TNF)-alpha production by resident macrophages (M phi) contributes to posttraumatic tissue injury. Hypoxia decreases cellular cyclic adenosine monophosphate (cAMP) levels and enhances M phi secretion of TNF-alpha following lipopolysaccharide (LPS) stimulation. Thus, tissue hypoxia associated with trauma likely synergizes with proinflammatory mediators in the induction of M phi TNF-alpha production through an influence on cAMP generation or degradation. It is unclear whether elevation of cellular cAMP inhibits LPS-stimulated TNF-alpha production by hypoxic M phi. Moreover, it is unknown whether the synergism of hypoxia with LPS can be abrogated by promotion of cAMP generation or inhibition of cAMP degradation.

METHODS

Rat peritoneal M phi were stimulated with Escherichia coli LPS (20 ng/ml) in a normoxic (room air with 5% CO(2)) or hypoxic (95% N(2) with 5% CO(2)) condition. TNF-alpha levels in cell-free supernatants were measured by enzyme-linked immunoassay. The beta-adrenoceptor agonist isoproterenol (ISP; 5.0 microM) and the adenylate cyclase activator forskolin (FSK; 50 microM) were applied to promote cAMP generation. The nonselective cyclic-3',5'-nucleotide phosphodiesterase (PDE) inhibitor 3-isobutyl-1-methylxanthine (IBMX; 1.0 mM) and the PDE III-specific inhibitor milrinone (200 microM) were used to inhibit cAMP degradation. The nondegradable cAMP analogue dibutyryl cAMP (dbcAMP; 100 microM) was applied to further determine the role of PDE. RESULTS. Although hypoxia alone had a minimal effect on TNF-alpha production, it dramatically enhanced LPS-stimulated TNF-alpha production (4.08 +/- 0.28 ng/10(6) cells in hypoxia plus LPS vs 1.63 +/- 0.26 ng/10(6) cells in LPS, 2.5-fold, P < 0.01). Promotion of cAMP generation by either ISP or FSK reduced TNF-alpha production by hypoxic cells. However, neither of these two agents abolished the synergism of hypoxia with LPS (1.68 +/- 0.13 ng/10(6) cells in ISP plus hypoxia plus LPS vs 0.55 +/- 0.04 ng/10(6) cells in ISP plus LPS, threefold; 1.17 +/- 0.03 ng/10(6) cells in FSK plus hypoxia plus LPS vs 0.33 +/- 0.02 ng/10(6) cells in FSK plus LPS, 3.5-fold; both P < 0.01). Inhibition of cAMP degradation with IBMX reduced TNF-alpha production in hypoxic cells and abrogated the synergism (0.31 +/- 0.11 ng/10(6) cells in IBMX plus hypoxia plus LPS vs 0.27 +/- 0.04 ng/10(6) cells in IBMX plus LPS, P > 0.05), and the PDE III inhibitor milrinone had a comparable effect. Moreover, dbcAMP also attenuated TNF-alpha production with abrogation of the synergistic effect of hypoxia (0.56 +/- 0.08 ng/10(6) cells in dbcAMP plus hypoxia plus LPS vs 0.46 +/- 0.04 ng/10(6) cells in dbcAMP plus LPS, P > 0.05).

CONCLUSIONS

The results show that elevation of cellular cAMP, either by promotion of generation or by inhibition of degradation, suppresses LPS-stimulated TNF-alpha production in hypoxic M phi. It appears that hypoxia synergizes with LPS in the induction of M phi TNF-alpha production through PDE-mediated cAMP degradation. Inhibition of PDE may be a therapeutic approach for suppression of synergistic induction of M phi TNF-alpha production by hypoxia and LPS in posttraumatic tissue.

TNF alpha is required for hypoxia-mediated right ventricular hypertrophy

Hypoxia has been shown to activate the pleiotropic cytokine TNFalpha in the lung. TNFalpha in turn, is known to induce pulmonary vasoconstriction. Additional effects of this cytokine in hypoxia mediated cardiopulmonary remodeling are poorly understood. To further evaluate the role of TNFalpha in chronic hypoxia we exposed TNFalpha null (TNFalpha-/-) and wild-type mice to three weeks of hypobaric hypoxia (10% O2). Equivalent erythocytosis (Hematocrit increased by > 40%) developed in both genetic backgrounds. In contrast, right ventricular systolic pressure increased in response to three weeks of hypoxia in the wild-type mice (> or = 75%), yet was unaltered in the TNFalpha-/- mice. Concomitantly right ventricular hypertrophy was attenuated in the TNFalpha-/- mice (35 +/- 5% increase) when compared to wild-type mice (124 +/- 6% increase p < 0.001, n > or = 20). Interestingly in both strains the lung wet weights increased to a similar degree in response to hypoxia. In conclusion, our data demonstrate that TNFalpha is an integral autocoid in chronic hypoxia mediated right ventricular hypertrophy. Moreover, additional components of cardiopulmonary remodeling may be regulated by TNFalpha signaling as suggested by the negligible right ventricular systolic pressure response to hypoxia in the absence of TNFalpha.

Randomized trial of phosphodiesterase inhibitors versus catecholamines in patients with acutely decompensated heart failure

Increased neurohormone and cytokine concentrations are associated with adverse outcome in patients with congestive heart failure, so minimizing these increases may improve outcome, even in the acute phase of decompensated heart failure. The present study was designed to test the hypothesis that phosphodiesterase inhibitors, but not catecholamines, could favorably affect neurohormone and cytokine profiles in patients with acutely decompensated heart failure. Twenty-nine patients underwent monitoring using a Swan-Ganz catheter and were randomly allocated to receive phosphodiesterase inhibitors (PDEI group, n=19) or catecholamines (CA group, n=10). Pulmonary capillary wedge pressure decreased significantly in both groups and cardiac output showed a slight, but not statistically significant increase, in both groups. There was a significant decrease in plasma brain natriuretic peptide concentration in the PDEI group, but not in the CA group, whereas plasma interleukin-6 concentration increased in the CA group, but not in the PDEI group. Phosphodiesterase inhibitors favorably affect neurohormone and cytokine concentrations in patients with acutely decompensated heart failure.

Effects of vesnarinone on peripheral circulating levels of cytokines and cytokine receptors in patients with heart failure: a report from the Vesnarinone Trial

STUDY OBJECTIVES

Proinflammatory cytokines may contribute to disease progression in heart failure by virtue of the direct toxic effects that these molecules exert on the heart and the circulation. Accordingly, there is interest in developing therapeutic agents with anticytokine properties that might be used as adjunctive therapy to modulate proinflammatory cytokine levels in patients with heart failure. Previous experimental studies suggested that vesnarinone has potent anticytokine properties in vitro. Therefore, we examined the effects of vesnarinone on circulating levels of cytokines and cytokine receptors in a large-scale, multicenter, clinical trial of patients with moderate-to-advanced heart failure: the Vesnarinone Trial (VEST).

METHODS

Circulating levels of tumor necrosis factor (TNF)-alpha, soluble TNF-receptor type 1, soluble TNF-receptor type 2, as well as interleukin (IL)-6 and soluble IL-6 receptor (sIL-6R) were measured on plasma samples by enzyme-linked immunosorbent assay at baseline and at 24 weeks in patients who were receiving placebo (n = 352), 30 mg of vesnarinone (n = 367), and 60 mg of vesnarinone (n = 327).

RESULTS

Treatment with 30 mg and 60 mg of vesnarinone had no effect on circulating levels of cytokines or cytokine receptors in patients with advanced heart failure over a 24-week period.

CONCLUSIONS

In contrast to the potent anticytokine effects observed with vesnarinone in experimental studies in vitro, the results of this clinical study suggest that vesnarinone does not have any measurable anticytokine effects in vivo in patients with moderate-to-advanced heart failure.

Therapeutic effects of FTY720, a new immunosuppressive agent, in a murine model of acute viral myocarditis

OBJECTIVES

This study examines the efficacy of FTY720 (FTY), a new immunosuppressor, in the treatment of acute viral myocarditis in a murine model.

BACKGROUND

Immunosuppressive agents have no proven therapeutic efficacy in experimental or clinical myocarditis.

METHODS

Encephalomyocarditis virus was inoculated i.p. in DBA/2 mice on day 0. Postinoculation treatment consisted of FTY 10 mg/kg/day p.o. (FTY group), or cyclosporine A (CsA) 40 mg/kg/day p.o. (CsA group) or distilled water p.o. only (control group). Survival until day 14, as well as cardiac histopathology, virus concentrations, cytokines (interleukin [IL]-2, IL-12, interferon [IFN]-gamma and tumor necrosis factor [TNF]-alpha) and nitric oxide (NO) on day 5 were examined.

RESULTS

In the control and CsA groups, all mice died within 10 and 7 days, respectively. However, in the FTY group, 27% of the animals survived up to day 14. Compared with the control group, 1) histological scores were significantly lower in the FTY group but unchanged in the CsA group; 2) virus concentration was significantly higher in the CsA group but not in the FTY group; 3) expressions of IL-2, IL-12 and IFN-gamma in the heart were suppressed in both the FTY and CsA groups, though suppression was weaker in the FTY group; 4) TNF-alpha and NO were significantly increased in the CsA group but not in the FTY group.

CONCLUSIONS

FTY720 had a significant therapeutic effect in acute experimental myocarditis without inducing excessive virus replication. This report is the first to describe a beneficial effect by an immunosuppressive agent in the treatment of acute viral myocarditis.

The role of inflammatory mediators in the failing heart: immunomodulation of cytokines in experimental models of heart failure

Congestive heart failure may be produced by a variety of disorders, including dilated cardiomyopathy, hypertension, and ischemic heart disease. We have developed experimental models of these diseases, and found gene expressions of proinflammatory cytokines increased in the hearts of these animals. Various drugs for heart failure modulate the production of cytokines in experimental models of heart failure. Pimobendan, an inhibitor of phosphodiesterase III prolonged survival, attenuated inflammatory lesions, and decreased the production of cytokines and nitric oxide. Recent studies have shown that these inhibitory effects are due to inhibition of activation of NF-kappaB. In contrast, digitalis increased the production of cytokines and exacerbated myocarditis. Interleukin-10 prolonged survival, attenuated myocardial injury, and appears promising as a treatment of heart failure due to viral myocarditis. Endothelin-1 plays an important pathophysiological role in heart failure, and treatment with an endothelin antagonist had a cardioprotective effect in experimental models of heart failure.

The systemic inflammatory response in heart failure

The physiologic diagnosis of heart failure has changed very little over the past several decades: heart failure is the inability of the cardiac output to meet the metabolic demands of the organism. The clinical definition of heart failure (also relatively unchanged) describes it as ventricular dysfunction that is accompanied by reduced exercise tolerance. Our understanding of the true pathophysiologic processes involved in heart failure have, however, changed. We have moved from thinking of heart failure as primarily a circulatory phenomenon to seeing it as a pathophysiologic state under the control of multiple complex systems. Over the past several years the dramatic explosion of research in the fields of immunology and immunopathology have added an additional piece to the puzzle that defines heart failure and have lead to an understanding of heart failure, at least in some part, as an 'inflammatory disease'. In this review we will examine several of the key inflammatory mediators as they relate to heart failure while at the same time attempting to define the source(s) of these mediators. We will examine key elements of the inflammatory cascade as they relate to heart failure such as: cytokines, 'proximal mediators' (e.g. NF-kappaB), and distal mediators (e.g. nitric oxide). We will end with a discussion of the potential therapeutic role of anti-inflammatory strategies in the future treatment of heart failure. Also, throughout the review we will examine the potential pitfalls encountered in applying bench discoveries to the bedside as have been learned in the field of septic shock research.

Bench to bedside: tumor necrosis factor-alpha: from inflammation to resuscitation

Proinflammatory mediators such as tumor necrosis factor-alpha (TNF) have been implicated in the pathophysiology in a number of acute disease states. Tumor necrosis factor-alpha can contribute to cell death, apoptosis, and organ dysfunction. Tumor necrosis factor-alpha can be generated with sepsis or ischemia-reperfusion by activation of cell mitogen-activated protein kinases and nuclear factor kappa B, leading to TNF production. A number of strategies to modulate TNF have been recently explored, including factors directed toward mitogen-activated protein kinases, TNF transcription, anti-inflammatory ligands, heat shock proteins, and TNF-binding proteins. However, TNF may also play an important role in the adaptive response to injury and inflammation. Control of the deleterious effects of TNF and other proinflammatory cytokines represents a realistic goal for clinical emergency medicine. The purpose of this article is to provide a background of relevance to emergency medicine academicians on the production and regulation of TNF, the acute effects of TNF on pathophysiology, and the rationale for therapeutic interventions directed toward TNF and the clinical experience with these strategies.

Amlodipine inhibits the production of cytokines induced by ouabain

Recent studies have suggested that cytokines are capable of modifying cardiovascular function and that drugs used in the treatment of heart failure have various modulating properties on the production of cytokines. More recently, we have found that ouabain induces the production of cytokines. This study was performed to examine the effects of calcium channel blockers on the production of cytokines induced by a cardiac glycoside. Human peripheral blood mononuclear cells (PBMC) were obtained from healthy volunteers. PBMC were cultured in 0.1, 1, 10, and 30 micromol/l amlodipine, diltiazem, and nifedipine in presence of 1 micromol/l ouabain. After 24 h of incubation, IL-1alpha, IL-1beta, IL-6, and TNF-alpha were measured in the culture supernatants by enzyme-linked immunosorbent assay. Ouabain induced the production of IL-1alpha, IL-1beta and IL-6, but not of TNF-alpha. Induction of IL-1beta was most prominent. The production of IL-1alpha, and IL-6 was inhibited by amlodipine in a concentration-dependent manner and was significantly decreased at a concentration of 10 micromol/l. IL-1beta production was also inhibited by 30 micromol/l amlodipine. In contrast, neither diltiazem nor nifedipine inhibited the production of these cytokines. The unique property of amlodipine to inhibit the production of IL-1alpha, IL-1beta and IL-6 may contribute to its beneficial effects in heart failure patients.

High doses of digitalis increase the myocardial production of proinflammatory cytokines and worsen myocardial injury in viral myocarditis: a possible mechanism of digitalis toxicity

Results of recent studies suggest that proinflammatory cytokines cause myocardial contractile dysfunction, and that the drugs used to treat heart failure modulate the production of cytokines. This study was designed to examine the effects of digoxin in a murine model of heart failure induced by viral myocarditis. Four-week-old inbred DBA/2 mice were inoculated intraperitoneally with encephalomyocarditis virus (EMCV). Digoxin was given orally in doses of 0.1, 1 or 10 mg/kg daily from the day of virus inoculation. Interleukin (IL)-1beta, IL-6 and tumor necrosis factor (TNF)-alpha production in the heart were measured on day 5 after EMCV inoculation by enzyme-linked immunosorbent assay. The 14-day mortality tended to be increased in mice treated with 1 mg/kg, and was significantly increased in the group treated with 10 mg/kg per day. Myocardial necrosis and cellular infiltration on day 6 were significantly more severe in the high-dose digoxin group than in the control group. In the animals treated with 1 mg/kg digoxin, IL-1beta was significantly higher than in the control group. Intracardiac TNF-alpha levels were increased in a dose-dependent manner. These results suggest that digoxin worsens viral myocarditis, and that its use in high doses should be avoided in patients suffering from heart failure due to viral myocarditis.

The changes of circulating tumor necrosis factor levels in patients with congestive heart failure influenced by therapy

Recent studies suggest that tumor necrosis factor-alpha (TNF-alpha) plays an important role in the pathogenesis of congestive heart failure and that drugs used in the treatment of heart failure have modulation effects on the production of TNF-alpha. To examine an alteration of circulating TNF-alpha concentration in patients with severe chronic heart failure after improving heart function and investigate the influence of agents on circulating TNF-alpha concentrations, we measured the plasma levels of TNF-alpha by enzyme linked immunoabsorbent assay in 31 patients and evaluated their heart functions before and after 72 h of therapy. The results showed that circulating TNF-alpha concentrations significantly decreased after therapy (from 124.36+/-14.85 pg/ml to 93.84+/-13.57 pg/ml, P<0.001). The circulating TNF-alpha concentrations of patients (n = 22) whose heart function was improved one class or more after therapy declined significantly (from 127.51+/-20.78 pg/ml to 91.54+/-18.56 pg/ml, P<0.01) but this situation did not exist in patients (n = 9) whose heart functions had no or little improvement. All patients were divided into three groups according to their management: 'group A' (n = 14) who received milrinone and angiotensin-converting enzyme inhibitors (ACEI), 'group B' (n = 6) who received milrinone but not ACEI and 'group C' (n = 11) who received ACEI and dobutamine but not milrinone. The circulating TNF-alpha concentration of patients in group A significantly declined (from 126.68+/-26.04 pg/ml to 95.92+/-24.79 pg/ml, P<0.01). No statistical significance of change of TNF-alpha concentration was found in patients in group B or group C, although a tendency of decline existed (from 119.92+/-34.72 pg/ml to 84.33+/-30.70 pg/ml and from 123.83+/-19.50 pg/ml to 96.37+/-16.62 pg/ml, respectively). These findings support that decreased plasma TNF-alpha level accompanies the improvement of heart function. This phenomenon may be explained by the special abilities of agents, such as ACEI and milrinone, to inhibit the TNF-alpha production.

Pimobendan inhibits the production of proinflammatory cytokines and gene expression of inducible nitric oxide synthase in a murine model of viral myocarditis

OBJECTIVES

This study was designed to examine the effects of pimobendan in a murine model of viral myocarditis in relation to proinflammatory cytokine production and nitric oxide (NO) synthesis by inducible NO synthase (iNOS) in the heart.

BACKGROUND

Pimobendan has been recently confirmed to improve both acute and chronic heart failure. Since the modulation of myocardial necrosis and contractile dysfunction by various proinflammatory cytokines may be partially mediated by the production of nitric oxide, the effects of pimobendan on the production ofproinflammatory cytokines and NO were investigated in an animal model of viral myocarditis involving heart failure.

METHODS

DBA/2 mice were inoculated with the encephalomyocarditis virus. To observe its effect on survival up to 14 days, pimobendan (0.1 mg/kg or 1 mg/kg) or vehicles were given from the day of virus inoculation (day 0) orally once daily. The effects of pimobendan on histological changes, cytokine production, NO production and iNOS gene expression in the heart were studied in mice treated either with pimobendan, 1 mg/kg or with vehicles only, and sacrificed seven days after virus inoculation.

RESULTS

The survival of mice improved in a dose-dependent fashion such that a significant difference (p < 0.02) was found between the higher-dose pimobendan group (20 of 30 [66.7%]) and the control group (11 of 30 [36.7%]). Histological scores for cellular infiltration (1.1+/-0.1 vs. 2.0+/-0.0, p < 0.001), intracardiac tumor necrosis factor (TNF)-alpha (18.2+/-1.8 vs. 35.8+/-4.2 pg/mg heart, p < 0.001) and interleukin (IL)-1beta (9.3 +/-1.2 vs. 26.6+/-7.1 pg/mg heart, p < 0.01) were significantly lower in the mice given pimobendan versus those of the control mice. Interleukin-6 levels (7.1+/-0.8 vs. 9.2+/-1.9 pg/mg heart) were also lower in the mice treated with pimobendan. Furthermore, intracardiac NO production was significantly (p < 0.001) less in the pimobendan group (0.165+/-0.004 nmol/mg heart) than in the control group (0.291+/-0.051 nmol/mg heart), and intracardiac iNOS gene expression in the mice given pimobendan was 74% lower than it was in the control animals (p < 0.01).

CONCLUSIONS

These findings suggest that the beneficial effects of pimobendan in viral myocarditis are partially mediated by the inhibition of both proinflammatory cytokine production and NO synthesis by iNOS.

Innovations in the pharmacologic management of heart failure

Improved understanding of the pathophysiologic course of heart failure has led to many advances in pharmacologic therapy. Angiotensin-converting enzyme inhibitors represent the first effort at targeting neurohormonal activation in chronic heart failure. More recently, beta-adrenergic receptor antagonists have been shown effective in blocking chronic sympathetic nervous system activation. The roles of digoxin and the newer, vasoselective calcium channel blockers in heart failure have been better defined. Other agents targeting the neurohormonal system are under investigation. These include angiotensin-receptor antagonists, aldosterone inhibitors, and endothelin antagonists. Experience with phosphodiesterase inhibitors and adrenergic agents has confirmed the importance of neurohormonal activation in progression of heart failure. Despite angiotensin-converting enzyme inhibitor, diuretic, and digoxin therapy, mortality in heart failure remains high. Careful manipulation of the neurohormonal response to heart failure holds promise for altering the course of the disease.

Tumor necrosis factor in the heart

The heart is a tumor necrosis factor (TNF)-producing organ. Both myocardial macrophages and cardiac myocytes themselves synthesize TNF. Accumulating evidence indicates that myocardial TNF is an autocrine contributor to myocardial dysfunction and cardiomyocyte death in ischemia-reperfusion injury, sepsis, chronic heart failure, viral myocarditis, and cardiac allograft rejection. Indeed, locally (vs. systemically) produced TNF contributes to postischemic myocardial dysfunction via direct depression of contractility and induction of myocyte apoptosis. Lipopolysaccharide or ischemia-reperfusion activates myocardial P38 mitogen-activated protein (MAP) kinase and nuclear factor kappa B, which lead to TNF production. TNF depresses myocardial function by nitric oxide (NO)-dependent and NO-independent (sphingosine dependent) mechanisms. TNF activation of TNF receptor 1 or Fas may induce cardiac myocyte apoptosis. MAP kinases and TNF transcription factors are feasible targets for anti-TNF (i.e., cardioprotective) strategies. Endogenous anti-inflammatory ligands, which trigger the gp130 signaling cascade, heat shock proteins, and TNF-binding proteins, also control TNF production and activity. Thus modulation of TNF in cardiovascular disease represents a realistic goal for clinical medicine.

Adenosine inhibits lipopolysaccharide-induced secretion of tumor necrosis factor-alpha in the failing human heart

BACKGROUND

The proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) has been implicated in the pathogenesis of congestive heart failure. Recent studies have shown that adenosine inhibits lipopolysaccharide (LPS)-induced expression of TNF-alpha in macrophages and rat cardiomyocytes. The aim of this study was to determine whether adenosine has a similar effect in the failing human heart.

METHODS AND RESULTS

Left ventricular muscle strips were obtained from seven patients with end-stage congestive heart failure undergoing heart transplantation or insertion of a left ventricular assist device. The muscle strips were incubated at 37 degrees C in 95% O2/5% CO2 and stimulated with LPS (10 microg/mL). TNF-alpha release in the supernatant was measured with ELISA, and muscle sections were stained for TNF-alpha. Muscle strips released TNF-alpha in the absence of LPS (0.22+/-0.05 pg x mL(-1) x mg wet wt[-1]). TNF-alpha was immunolocalized to the cardiac myocyte, suggesting that the myocyte is a source for TNF-alpha production. Adenosine (10 micromol/L) decreased TNF-alpha by 40% (P<.05). The selective adenosine A2 receptor agonist DPMA (10 micromol/L) decreased TNF-alpha release by 87% (P<.001), whereas ITu (10 micromol/L), an adenosine-regulating agent that increases endogenous adenosine concentration, inhibited TNF-alpha release by 93% (P<.001).

CONCLUSIONS

Adenosine can significantly diminish TNF levels in the failing human heart and may represent a new pharmacological intervention in congestive heart failure.

Calcium channel blocker-induced protection against cardiovascular damage

The therapeutic effects of calcium channel blockers on heart failure are controversial. However, a recent clinical trial demonstrated a favorable effect of amlodipine on survival rates in patients with heart failure resulting from nonischemic dilated cardiomyopathy. There are a number of studies showing that cytokines generated by activated immune cells cause an increase in nitric oxide (NO) via induction of NO synthase (NOS), which results in a direct negative inotropic effect and a modulation of inotropic responsiveness. Increases in inflammatory circulating cytokines have been detected in patients with heart failure and cardiomyopathy, elevated plasma levels of nitrite/nitrate in patients with heart failure have been reported, and inducible NOS (iNOS) has been found in ventricular tissue from patients with dilated cardiomyopathy. In our recent study, amlodipine improved histopathological lesions in the heart and survival rates in a murine model of nonischemic heart failure induced by encephalomyocarditis virus. Amlodipine inhibited NO production in vitro and decreased the number of iNOS positive cells in vivo. In this model, the therapeutic effect of amlodipine on myocardial injury is considered in part to result from inhibition of overproduction of NO. In this review, the possible roles of cytokines and NO in the pathophysiology of heart failure are discussed, along with the opportunities for therapeutic intervention.

The use of cytokine inhibitors. A new therapeutic insight into heart failure

Cytokines are being increasingly recognized as important factors in the pathogenesis and pathophysiology of heart failure. Elevated levels of circulating cytokines have been reported in patients with heart failure, and various cytokines have been shown to depress myocardial contractility in vitro and in vivo. We have recently compared the effects on cytokine production of drugs for therapy of heart failure that have different effects on survival. Amrinone, pimobendan and vesnarinone, phosphodiesterase III inhibitors that have been shown to have short term haemodynamic benefits, inhibited TNF-alpha production. Differential modulation of the production of IL-1beta and IL-6 was observed; amrinone and pimobendan enhanced the production of IL-1beta, whereas vesnarinone did not. As inotropic agents differentially modulate cytokine production, these agents may interfere with induction of inducible nitric oxide (NO) synthase through an inhibition of cytokine formation. Although differential modulation of the production of NO by inotropic agents may explain their different effect in patients with heart failure, further study is necessary to reach this conclusion. We have shown that amlodipine increases the survival of mice with viral myocarditis and inhibits expression of inducible NO synthase and production of NO in vivo and in vitro. The therapeutic effect of amlodipine may in part result from inhibition of overproduction of NO. As we learn more about the pathophysiological and pathogenetic role of cytokines in heart failure, it should be possible to design better and more targeted pharmacological agents. Furthermore, the investigation of inotropic agents that are effective against the production of cytokines may help in the classification of these agents.

Mechanisms of cardiac preconditioning: ten years after the discovery of ischemic preconditioning

Cardiac preconditioning describes the phenomenon by which transient ischemia induces myocardial protection against subsequent ischemia and reperfusion injury. Ten years have passed since the original description of this potent cardiac protective strategy and within this period tremendous progress has been made elucidating the mechanisms of preconditioning. Mechanistic understanding may allow safe clinical application. This review (1) recalls the history of preconditioning and how it relates to the history of the investigation of endogenous adaptation; (2) summarizes the current mechanistic understanding of early preconditioning; (3) compares and contrasts the mechanisms of early versus delayed preconditioning; (4) suggests potential anti-inflammatory aspects of preconditioning; (5) examines limitations in laboratory models of preconditioning; and (6) explores the potential of using preconditioning clinically.

Amiodarone inhibits production of tumor necrosis factor-alpha by human mononuclear cells: a possible mechanism for its effect in heart failure

BACKGROUND

Recent studies suggest that cytokines such as tumor necrosis factor (TNF)-alpha and interleukins (ILs) are capable of modulating cardiovascular function and that drugs used in the treatment of heart failure have various modulatory effects on the production of cytokines. This study was performed to examine the effects of amiodarone (a drug shown to be beneficial in some patients suffering from heart failure) versus other antiarrhythmic agents on the production of cytokines in vitro.

METHODS AND RESULTS

Human peripheral blood mononuclear cells (PBMC) were obtained from healthy volunteers. PBMC were cultured with 0.1, 1, and 10 micromol/L of amiodarone, quinidine, disopyramide, and lidocaine in the presence of lipopolysaccharide. After 24 hours' incubation, TNF-alpha, IL-1beta, and IL-6 were measured in the culture supernatants by an enzyme-linked immunosorbent assay. TNF-alpha production was inhibited by amiodarone but stimulated by quinidine in a concentration-dependent manner. Disopyramide and lidocaine tended to increase TNF-alpha production. IL-6 production was decreased by amiodarone in all concentrations but was increased significantly by disopyramide. Modulation of IL-1beta production by amiodarone was biphasic and significantly increased at a concentration of 10 micromol/L.

CONCLUSIONS

These previously unrecognized immunomodulatory effects of amiodarone may contribute to its beneficial effects in heart failure patients.

Modulation of cytokine production and protection against lethal endotoxemia by the cardiac glycoside ouabain

BACKGROUND

Recent studies have shown that cytokines are capable of modulating cardiovascular function and that some drugs used in the treatment of heart failure variably modulate the production of cytokines. To examine whether cardiac glycosides also modulate cytokine production, we evaluated the effects of ouabain on the production of cytokines in vitro and in vivo.

METHODS AND RESULTS

Human peripheral blood mononuclear cells (PBMC) were obtained from healthy volunteers. PBMC were cultured with or without ouabain in the presence or absence of lipopolysaccharide (LPS). Ouabain induced the production of interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha in PBMC and induced mRNA of these cytokines, an induction apparently at the transcriptional level. Amiloride, staurosporin, and genistein inhibited cytokine production, and protein kinase C and tyrosine kinase appeared to be involved in the modulation of cytokine production induced by ouabain. However, when PBMC were stimulated with LPS, ouabain suppressed the production of IL-6 and TNF-alpha. To investigate whether ouabain modulates cytokine production in vivo, we evaluated the effects of ouabain in LPS-treated mice. Ouabain was found to protect against LPS-induced lethal toxicity in mice and decreased circulating IL-6 and TNF-alpha levels in vivo.

CONCLUSIONS

These previously unrecognized immunomodulating effects of a cardiac glycoside may explain either the beneficial or the detrimental effects of these drugs in heart failure patients.

Molecular and immune mechanisms in the pathogenesis of cardiomyopathy--role of viruses, cytokines, and nitric oxide

Myocarditis is thought to be commonly caused by various viruses, and accumulating evidence links viral myocarditis with the eventual development of dilated cardiomyopathy. Recently, the importance of hepatitis C virus infection was noted in patients with dilated and hypertrophic cardiomyopathy. Cytokines are being increasingly recognized as an important factor in the pathogenesis and pathophysiology of myocarditis and cardiomyopathy. Elevated levels of circulating cytokines have been reported in patients with heart failure, and various cytokines have been shown to depress myocardial contractility in vitro and in vivo. A number of reports have shown that cytokines generated by activated immune cells cause an increase in nitric oxide (NO) via induction of NO synthase. Increased generation of NO may induce negative inotropism and myocardial damage. This review discusses the etiology and pathogenesis of myocarditis and cardiomyopathy from this point of view.

Vesnarinone: a potential cytokine inhibitor

Cytokines are soluble peptides that mediate cell-to-cell interactions via specific cell surface receptors. There is a growing body of evidence that cytokines may play an important role in the pathogenesis of heart failure, and the intriguing possibility has been postulated that anticytokine therapy may favorably alter the clinical outcome of heart failure. As cytokines are essentially pleiotropic and redundant in nature, elimination of a single cytokine from the biologic system often fails to have major consequences. Therefore, the prospect has been raised for developing immunomodulating therapy for heart failure, enabling the simultaneous modification of the actions of multiple cytokines. The recently observed clinical benefit of vesnarinone on mortality and morbidity in patients with heart failure has been attributed to this immunomodulation. In the murine model of myocarditis and heart failure, vesnarinone enhanced the cumulative survival rate without affecting virus replication on virus-induced cytopathic effects. Vesnarinone inhibited excessive cytotoxicity of natural killer cells presumably by suppressing activation mediated by K channel inhibition. Vesnarinone also inhibited the production of cytokines. Cytokine inhibitory effects were different from those of other phosphodiesterase inhibitors or direct elevation of intracellular cyclic adenosine monophosphate, suggesting that the effects did not appear to be derived solely from a cyclic adenosine monophosphate-elevating action. Such cytokine regulation also appeared to be different in normal patients and in patients with heart failure. In conclusion, vesnarinone exerts an immunomodulating effect by suppressing natural killer cell activity and inhibiting cytokine production. These findings may hold open the hope that immunomodulation could be a new therapeutic modality. However, further studies on the long-term safety and efficacy of vesnarinone are warranted to establish the eventual status of this agent in the treatment of heart failure.