Increased circulating cytokines in patients with myocarditis and cardiomyopathy

Beneficial effects of amlodipine in a murine model of congestive heart failure induced by viral myocarditis. A possible mechanism through inhibition of nitric oxide production

BACKGROUND

Although calcium channel blockers have not been shown to be beneficial for the treatment of patients with heart failure, a recent clinical trial demonstrated a favorable effect of amlodipine on the survival of patients with heart failure resulting from nonischemic dilated cardiomyopathy. We investigated the effects of amlodipine on a murine model of congestive heart failure induced by the M variant of encephalomyocarditis virus (EMCV).

METHODS AND RESULTS

Four-week-old male DBA/2 mice were inoculated with EMCV and administered amlodipine, diltiazem, or vehicle PO for 2 weeks. The heart weight-to-body weight ratio and the histopathological grades of myocardial lesions were significantly lower and survival was significantly increased in the amlodipine-treated group (P < .01, P < .05, and P < .05, respectively) than in the control group. In vitro, amlodipine added to murine J774A.1 macrophages concomitant with EMCV inhibited nitrite formation in a concentration-dependent manner, but diltiazem did not. Furthermore, NG-monomethyl-L-arginine, an inhibitor of NO synthesis, decreased myocardial lesions significantly in this murine model. Immunohistochemistry revealed that the number of cells stained with antibody against an inducible NO synthase decreased significantly in the amlodipine-treated group compared with that in the control group (P < .01).

CONCLUSIONS

Amlodipine appears to have a protective effect against myocardial injury in this animal model of congestive heart failure. The therapeutic effect of amlodipine may be in part resulting from inhibition of overproduction of NO.

Inotropic agents in the treatment of heart failure: despair or hope?

Depression of myocardial contractility plays an important role in the development of heart failure; therefore, intensive interest and passion have been generated to develop cardiotonic agents to improve the contractile function of the failing heart. Inotropic agents that increase cyclic AMP, either by increasing its synthesis or reducing its degradation, exert dramatic short-term hemodynamic benefits, but these acute effects cannot be extrapolated into long-term improvement of the clinical outcome in patients with advanced heart failure. Administration of these agents to an energy-starved failing heart would be expected to increase myocardial energy use and could accelerate disease progression. The role of digitalis in the management of heart failure has been controversial, but ironically the drug has now been proved to favorably affect the neurohormonal disorders and its reevaluation is now being intensively investigated. More recently, attention has been focused on other inotropic agents that have a complex and diversified mechanism. Recent clinical studies have demonstrated that they are potentially useful in the long-term treatment of heart failure patients. These agents have some phosphodiesterase-inhibitory action but also possess additional effects, including acting as cytokine inhibitors, immunomodulators, or calcium sensitizers. However, their therapeutic ratio is narrow and further studies are warranted to establish their optimal doses and their eventual status in the treatment of heart failure.

The effect of tumor necrosis factor-alpha on cardiac structure and function: a tale of two cytokines

The ability of the myocardium to successfully compensate for and adapt to stress, ultimately determines whether the heart will decompensate and fail, or whether instead it will maintain preserved function. Despite the importance of the myocardial response to environmental stress, very little is known with respect to the biochemical mechanisms that are responsible for mediating and integrating the stress response in the heart. In the present review we will summarize recent experimental material which suggests that tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine that has been identified consistently in virtually all forms of cardiac injury, may play an important role in mediating and integrating the myocardial response to stress. The theme that will emerge from this discussion is that the short-term expression of TNF-alpha within the heart may provide the heart with an adaptive response to stress, whereas long-term expression of TNF-alpha may be frankly maladaptive by producing cardiac decompensation.

Immunomodulation: a new horizon for medical treatment of heart failure

Recently, the intriguing possibility has been raised that heart failure may be mediated by the biological effects of cytokines. Indeed, we found elevation of plasma concentrations of various cytokines in patients with myocardial disease. We also detected positive tumor necrosis factor (TNF-alpha) immunoreactivity in right atrial tissues obtained during surgery from patients with severe heart failure. Therefore, we postulated that some aspects of heart failure may be related to non-lethal down-modulation of cardiac function by immune cells and their cytokines. Testing this hypothesis in an experimental model of murine myocarditis, we found that injection of recombinant human TNF-alpha increased mortality of the animals infected with myocarditis virus. The anti-TNF-alpha monoclonal antibody improved survival and attenuated the myocardial lesions. Whereas, administration of recombinant human IL-2 in the acute viremic stage increased survival rate, and resulted in less intense pathological changes in the myocardium while in the subacute aviremic stage, the same amount of IL-2 reduced survival rate and exacerbated severity of the disease. Therefore, cytokine release may initiate a beneficial inflammatory and immune response in the acute phase of the disease process, but the continued induction of cytokines and the enhanced natural killer (NK) cell activity in the later stage are no longer protective. Vesnarinone, a recently synthesized inotropic agent which has proved to benefit patients with congestive heart failure by improving prognosis, also increased the survival of individual subjects in the above-mentioned murine model of heart failure. Cytotoxicity of NK cells obtained from the virus infected animals was substantially reduced when treated with vesnarinone. Vesnarinone also inhibited production of TNF-alpha and other cytokines from stimulated human lymphocytes and cultured murine splenocytes. We conclude, therefore, that inhibition of NK cell activity and suppression of cytokine production appear to be important immunological defense mechanisms which could contribute to the observed salutary effects of vesnarinone in the treatment of chronic heart failure. More broadly, immunomodulation could pave the way for a new frontier in the management of heart failure.

Stress activated cytokines and the heart

The ability of myocardium to successfully compensate for, and adapt to, stress ultimately determines whether the heart will decompensate and fail, or whether it will instead maintain preserved function. Despite the importance of the myocardial response to environmental stress, very little is known with respect to the biochemical mechanisms that are responsible for mediating and integrating the stress response in the heart. In the present review we will summarize recent experimental material which suggests that cytokines that are expressed within the myocardium in response to a environment injury, namely tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1) and interleukin-6 (IL-6), may play an important role in initiating and integrating homeostatic responses within the heart. However, these 'stress-activated' cytokines all have the potential to produce cardiac decompensation when expressed at sufficiently high concentrations. Accordingly, the theme that will emerge from this discussion is that the short-term expression of stress-activated cytokines within the heart may provide the heart with an adaptive response to stress, whereas long-term expression of these molecules may be frankly maladaptive by producing cardiac decompensation.

Circulating levels of cytokines and their endogenous modulators in patients with mild to severe congestive heart failure due to coronary artery disease or hypertension

OBJECTIVES

This study sought to determine the circulating levels of cytokines and their respective endogenous modulators in patients with congestive heart failure of variable severity.

BACKGROUND

Activation of immune elements localized in the heart or periphery, or both, may promote release of cytokines in patients with congestive heart failure. Although an increased circulating level of tumor necrosis factor-alpha (TNF-alpha) and its soluble receptor type II (sTNF-RII) is well documented, less is known about other cytokines (i.e., interleukin-1-beta [IL-1-beta], interleukin-6 [IL-6] and interleukin-2 [IL-2] and their soluble receptor/receptor antagonists).

METHODS

Circulating levels of TNF-alpha and sTNF-RII, IL-1-beta, IL-1 receptor antagonist (IL-1-Ra), IL-6, IL-6 soluble receptor (IL-6-sR), IL-2 and IL-2 soluble receptor-alpha were measured using enzyme-linked immunosorbent assay kits (Quantikine, R&D Systems) in 80 patients with congestive heart failure due to coronary artery disease or hypertension. The severity of their symptoms, which ranged from New York Heart Association functional class I to IV, was confirmed by measurement of peak oxygen consumption.

RESULTS

The percentage of patients with elevated levels of cytokines and their corresponding soluble receptor/receptor antagonists significantly increased with functional class. For TNF-alpha and IL-1-beta, the percentage of patients with elevated levels of soluble receptor/receptor antagonists was higher than that of patients with elevated levels of the cytokine itself. For IL-6, the percentage of patients with elevated levels of IL-6-sR tended to be lower than that of patients with elevated levels of IL-6. All but two patients had undetectable levels of IL-2, and all but seven had levels of IL-2-sR within a normal range.

CONCLUSIONS

In patients with congestive heart failure, circulating levels of cytokines increased with the severity of symptoms. In these patients, circulating levels of sTNF-RII and IL-1-Ra are more sensitive markers of immune activation than are circulating levels of TNF-alpha and IL-1-beta, respectively. Levels of IL-2 and IL-2-sR are not elevated when congestive heart failure is due to coronary artery disease or hypertension.

Basic mechanisms in heart failure: the cytokine hypothesis

Although the development and progression of heart failure have traditionally been viewed as hemodynamic disorders, there is now an increasing awareness that the syndrome of heart failure cannot be simply and/or precisely defined solely in hemodynamic terms. The inability of the so-called hemodynamic hypothesis to explain the progression of heart failure has given rise to the notion that heart failure may progress as a result of the overexpression of an ensemble of biologically active molecules referred to generically as neurohormones. More recently, it has become apparent that in addition to neurohormones, another portfolio of biologically active molecules, termed cytokines, are also expressed in the setting of heart failure. This article reviews recent clinical and experimental material that suggests that the cytokines, much like the neurohormones, may represent another class of biologically active molecules that are responsible for the development and progression of heart failure.

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.

Cardiac rescue of an infant with fulminant myocarditis using extracorporeal membrane oxygenation

A 7-month-old boy presented with fulminant myocarditis. He was in cardiac shock and cardiac dysfunction progressed despite aggressive support. Extracorporeal membrane oxygenation (ECMO) was applied for 8 days and he recovered with mild dilated cardiomyopathy.

Inotropic agents differentially inhibit the induction of nitric oxide synthase by endotoxin in cultured macrophages

We investigated the effects of inotropic agents with phosphodiesterase III inhibitory properties, amrinone, pimobendan and vesnarinone, and cell permeable cyclic nucleotide analogue, 8-bromo adenosine 3'5'-cyclic monophosphate (8 Br-cAMP) on the induction of nitric oxide synthase (NOS) by lipopolysaccharide in J774A.1 macrophages in vitro. Although all three inotropic agents inhibited nitrite accumulation, the degree of inhibition was different, with pimobendan being the most potent inhibitor and amrinone the least. Vesnarinone inhibited nitrite formation biphasically. 8 Br-cAMP increased nitrite production at high concentrations, suggesting that the inhibitory effects of inotropic agents could not be explained by an increase in cAMP. Although differential inhibition of inducible NOS by inotropic agents may explain the different effects of these drugs in patients with heart failure, further study is necessary to reach this conclusion.

Increased serum concentrations of interleukin-1 beta in patients with coronary artery disease

OBJECTIVE

To assess serum interleukin-1 beta (IL-1 beta) concentrations in patients with ischaemic heart disease, to characterise subgroups of patients with raised IL-1 beta concentrations, and to examine whether serum IL-1 beta concentrations correlate with non-specific indices of inflammation.

DESIGN

Survey study of patients with ischaemic heart disease.

SETTING

Cardiac catheterisation laboratory of a tertiary medical centre.

PATIENTS

Consecutive patients with angina pectoris and patients recovering from uncomplicated acute myocardial infarction and undergoing elective coronary angiography.

RESULTS

Mean(SD) serum IL-1 beta concentrations were higher (P < 0.001) in patients with angina and < 50% coronary artery stenosis (n = 11; 18.8(19.9) pg/ml), patients with angina > or = 50% stenosis (n = 23; 10.2(11.4) pg/ml), and patients 8(0.8) days post-infarction (n = 13; 4.4(5.8) pg/ml) than in 15 healthy, age-matched controls (0.3(0.5) pg/ml). Serum IL-1 beta concentrations did not correlate with total blood leucocyte counts (r = -0.07, P = NS), blood lymphocyte counts (r = -0.24, P = NS), and blood monocyte counts (r = -0.29, P = NS), or with fibrinogen (r = -0.16, P = NS) and C-reactive protein concentrations (9(10.5) mg/dl v 14.1(19) mg/dl for patients with undetectable and detectable concentrations, respectively, P = NS).

CONCLUSION

Serum IL-1 beta concentrations are raised in patients with ischaemic heart disease, in particular in those with minimal coronary artery disease and angina. The precise role of IL-1 beta in coronary artery disease remains to be determined.

Proinflammatory cytokine levels in patients with depressed left ventricular ejection fraction: a report from the Studies of Left Ventricular Dysfunction (SOLVD)

OBJECTIVES

This study sought to assess proinflammatory cytokine levels in patients in the studies of left ventricular dysfunction trial (SOLVD) in relation to both their New York Heart Association functional classification and their neurohormonal status before randomization.

BACKGROUND

Elevated levels of tumor necrosis factor-alpha have been identified in 30% to 40% of patients with heart failure. However, it is unclear which subsets of patients with heart failure elaborate tumor necrosis factor-alpha. It is also unclear what the mechanism for the increased expression of proinflammatory cytokines is.

METHODS

Tumor necrosis factor-alpha and interleukin-6 levels were analyzed by enzymes-linked immunoassay using randomly selected plasma samples from patients in functional classes I to III who were enrolled in neurohormonal substudies of the SOLVD trial; age-matched healthy subjects served as the control group.

RESULTS

Plasma levels of tumor necrosis factor-alpha (p < 0.001) were elevated in patients in functional classes I to III ([mean +/- SD] 1.95 +/- 0.54, 2.63 +/- 0.48, 6.4 +/- 1.9 pg/ml, respectively) compared with age-matched control subjects (0.75 +/- 0.05 pg/ml) and were progressively elevated in relation to decreasing functional status of the patient. Plasma levels of interleukin-6 (p < 0.001) were elevated in patients in functional classes I to III (3.3 +/- 0.55, 6.2 +/- 1.1, 5.22 +/- 0.9 pg/ml, respectively) compared with age-matched control subjects (1.8 +/- 0.5 pg/ml and were progressively elevated in relation to decreasing functional status of the patient. Cox proportional-hazards analysis showed that there was a trend toward significance between plasma tumor necrosis factor-alpha (p < 0.07) and survival, whereas there was no significant relation for plasma interleukin-6 (p < 0.72). Except for atrial natriuretic factor, which correlated weakly (r = 0.23, p = 0.04) with circulating tumor necrosis factor-alpha levels, there was no significance correlation between neurohormonal and proinflammatory cytokine levels.

CONCLUSIONS

Circulating levels of proinflammatory cytokines increase in patients as their functional heart failure classification deteriorates. Moreover, activation of the neurohumoral axis is unlikely to completely explain the elaboration of proinflammatory cytokines in heart failure.

Abnormal cytokine profiles in patients with idiopathic dilated cardiomyopathy and their asymptomatic relatives

OBJECTIVES

Immunological abnormalities in idiopathic dilated cardiomyopathy (DCM) include an increase in soluble interleukin (IL)-2 receptor, disease specific cardiac autoantibodies, an HLA-DR4 association, and familial aggregation of disease; however, cytokine profiles have not been defined. Serum concentrations of IL-2, IL-4, IL-10, and IL-12 were measured in patients with DCM (WHO criteria), relatives with asymptomatic left ventricular enlargement (LVE), patients with ischaemic heart failure (IHD), and healthy controls.

DESIGN

Serum from 20 individuals from each of the four groups was assayed for cytokine concentrations by a commercial enzyme linked immunosorbent assay.

RESULTS

IL-2 concentrations were abnormally increased in DCM patients and relatives with LVE. Concentrations of IL-10 were increased in DCM patients. Concentrations of IL-4 and IL-12 were not increased in any of the groups.

CONCLUSION

These abnormalities may reflect defective/inappropriate T cell function in patients with DCM and in their relatives with LVE.

Tumor necrosis factor-alpha and tumor necrosis factor receptors in the failing human heart

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine that produces negative inotropic effects in the heart. Recently, elevated levels of TNF-alpha have been reported in patients with advanced congestive heart failure. Although TNF-alpha is thought to exert its deleterious effects by binding to two cell surface receptors, TNFR1 and TNFR2, the level of expression and regulation of TNF receptors in the heart in cardiac disease states is not known.

METHODS AND RESULTS

We examined mRNA and protein levels for TNFR1, TNFR2, and TNF-alpha in explanted hearts from organ donors as well as in patients with end-stage dilated cardiomyopathy (DCM) and ischemic heart disease (IHD). Northern blot analysis revealed that mRNA for TNFR1 and TNFR2 was present in nonfailing, DCM, and IHD hearts. TNFR1 and TNFR2 receptor protein levels, as measured by ELISA, were decreased 60% in DCM and IHD patients compared with nonfailing hearts (P < .005). To determine a potential mechanism for the decrease in TNF receptor expression, we measured levels of circulating soluble TNF receptors (sTNFRs) in DCM and IHD patients. This analysis showed that there was a significant one-and-a-half to threefold increase in sTNFRs in DCM (P < .03) and IHD patients (P < .001). Another important finding was that TNF-alpha mRNA and TNF-alpha protein were present in the explanted hearts from DCM and IHD patients but not in nonfailing hearts.

CONCLUSIONS

In summary, the results of this study constitute the initial demonstration that TNF receptor proteins are dynamically regulated in patients with advanced congestive heart failure. Moreover, the observation that failing hearts express elevated levels of TNF-alpha suggests that overexpression of this cytokine may be one of several different maladaptive mechanisms responsible for the progressive cardiac decompensation that occurs in advanced heart failure.

Elevated circulating levels of tumor necrosis factor in patients with mitral valve disease and ventricular septum defect

Elevated levels of circulating tumor necrosis factor (TNF)-alpha have been reported in patients with decreased left ventricular ejection fraction. Also, TNF has been reported to depress myocardial contractility. In our previous study, no correlation was found between the plasma level of TNF and clinical parameters in patients with cardiomyopathy. In the present study, we detected elevated levels of circulating TNF-alpha in 5 out of 15 patients with mitral valve disease and in 1 patient with ventricular septal defect whose left ventricular ejection fraction was within the normal range. The levels of TNF-alpha were not correlated with any hemodynamic parameters. Further studies are necessary to clarify the mechanisms of the regulation and effects of TNF-alpha in patients with chronic heart failure.

Inotropic agent vesnarinone inhibits cytokine production and E-selectin expression in human umbilical vein endothelial cells

The cytokine modulating effects of inotropic agents on human umbilical vein endothelial cells (HUVEC) were investigated. Confluent HUVEC in 24-well plates were treated with inotropic agents and then stimulated with 10 ng/ml of human interleukin (IL)-1 beta. After 24 h of incubation, the cytokine levels in the culture supernatants were determined by specific enzyme-linked immunosorbent assay (ELISA) kits. Vesnarinone [OPC-8212; 3,4-dihydro-6-(4-(3,4-dimethoxybenzoil)-1-piperazinyl)-2(1H)- quinolinone] at 26 mumol/l significantly suppressed the production of IL-6, granulocyte macrophage colony stimulating factor (GM-CSF) and granulocyte colony stimulating factor (G-CSF) induced by IL-1 beta. Although 8 bromoadenosine 3'5' cyclic monophosphate (8Br-cAMP) at 100 mumol/l also inhibited the production of these cytokines, the inhibitory effect was less marked than that of vesnarinone. Amrinone at 26 mumol/l and NKH477 at 10 nmol/l also had a less marked inhibitory effect against the production of IL-6. Next, the inhibitory effect of inotropic agents against the expression of the adhesion molecules of HUVEC was measured by a cell ELISA method. Vesnarinone at 26 mumol/l and NKH477 at 10 mumol/l, a water soluble forskolin derivative used as a positive control, both significantly inhibited the expression of E-selectin induced by 10 ng/ml of human tumor necrosis factor (TNF)-alpha. Amrinone at 26 mumol/l did not inhibit the expression of E-selectin. The level of HUVEC cAMP induced by vesnarinone at 26 mumol/l was much lower than that induced by NKH477 at 10 mumol/l. Moreover, according to a 3-(4,5-dimethyl-thiazol-2yl)-2,5-diphenyl tetrazolium bromide (MTT) cell viability assay, vesnarinone did not affect the viability of HUVEC. The immunosuppressive effects of vesnarinone described above are not derived from either a cAMP elevating effect or a cytotoxic effect against HUVEC. Although the cytokine network in heart failure has not yet been elucidated, patients with congestive heart failure might benefit from the immunomodulating effects of inotropic agents.

Tumor necrosis factor-alpha and the failing human heart

Tumor necrosis factor-alpha (TNF alpha) is a proinflammatory cytokine with negative inotropic effects. Recently, elevated levels of TNF alpha have been identified in patients with advanced heart failure. Although the clinical significance of this finding is unclear at present, there is increasing evidence that this cytokine may play a primary pathophysiologic role in the development and pathogenesis of heart failure in humans. Indeed, many of the clinical hallmarks of heart failure, including left ventricular dysfunction, cardiomyopathy, and pulmonary edema can be explained by the known biological effects of TNF alpha in humans. The present review will summarize recent evidence with regard to the biological role for TNF alpha in the adult mammalian heart, as well as summarize the increasing body of clinical information that implicates this cytokine in the pathophysiology of heart failure.

Cell death in the failing heart: role of an unnatural growth response to overload

Hypertrophy of the overloaded heart, characterized by an increased number of sarcomeres, provides an adaptive, short-term response. However, when cardiac overload is long-standing, the hypertrophic response appears to cause shortened myocyte survival. The mechanisms responsible for the deleterious effects of chronic myocardial hypertrophy may include a maladaptive growth response of the mature heart. Because terminally differentiated adult cardiac myocytes have little or no capacity to divide, stimuli that promote growth in the overloaded adult heart cannot lead to normal cell division. Instead, overload initiates an unnatural growth response that appears to shorten cardiac myocyte survival, possibly because the same growth factors that mediate the hypertrophic response of the adult heart can also induce programmed cell death (apoptosis). The converting enzyme inhibitors and nitrates, which have growth-inhibitory as well as vasodilator effects, may improve prognosis in heart failure by inhibiting the production of transcription factors. These transcription factors stimulate both the unnatural growth response to overload and stimuli that lead to apoptosis. Since both beta-adrenergic agonists and cytokines, such as tumor necrosis factor-alpha, can stimulate production of similar transcription factors, evidence suggests that beta blockers and vesnarinone improve the prognosis in patients with heart failure possibly because of their ability to inhibit maladaptive growth.

Cardiomyopathy: a role for nitric oxide?

The negative inotropism, myocardial dilatation and cytotoxicity in inflammatory heart disorders may be due to increased generation of nitric oxide (NO) by immunological induction of a high output NO pathway. This short review discusses the initial experiments which lead to this hypothesis, and evaluates data that this pathway exists in animal and human cardiomyopathic disorders. It is proposed that manipulation of this pathway may prove to be beneficial in patients with these disorders.