Cytokines in heart failure: pathogenetic mechanisms and potential treatment

Recent studies have shown that patients with heart failure overexpress a class of biologically active molecules, generically referred to as pro-inflammatory cytokines. This article will review recent clinical and experimental material that suggests that pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), and interleukin-6 (IL-6) may play a role in the pathogenesis of congestive heart failure. In addition, we will review recent studies that suggest that antagonizing cytokines may represent a novel target for heart failure therapy.

Intravenous immune globulin in the therapy of peripartum cardiomyopathy

OBJECTIVES

We sought to evaluate the effect of therapy with intravenous immune globulin on recovery of left ventricular function in women presenting with peripartum cardiomyopathy.

BACKGROUND

Peripartum cardiomyopathy is a rare complication of pregnancy that results in significant morbidity and mortality in women of childbearing age. Intravenous immune globulin has been reported to improve left ventricular systolic function in patients with acute dilated cardiomyopathy and myocarditis, but its effectiveness in peripartum cardiomyopathy is unknown.

METHODS

In this retrospective study, we compared the clinical outcomes of six women with peripartum cardiomyopathy treated with intravenous immune globulin (2 g/kg) with those of 11 recent historical control subjects. All women in the study were referred between 1991 and 1998 with class II to IV heart failure and a left ventricular ejection fraction of <0.40. Left ventricular ejection was reassessed during early follow-up (6.1+/-2.9 months).

RESULTS

The two groups did not differ in terms of baseline left ventricular ejection fraction, left ventricular end-diastolic diameter, months to presentation, age or multiparity. The improvement in left ventricular ejection fraction in patients treated with immune globulin was significantly greater than in the conventionally treated group (increase of 26+/-8 ejection fraction units vs. 13+/-13, p = 0.042).

CONCLUSIONS

In this small retrospective study of women with peripartum cardiomyopathy, patients treated with immune globulin had a greater improvement in ejection fraction during early follow-up than patients treated conventionally. Given the poor prognosis of women with peripartum cardiomyopathy who do not improve, this therapy merits further study.

Safety and efficacy of a soluble P75 tumor necrosis factor receptor (Enbrel, etanercept) in patients with advanced heart failure

BACKGROUND

Although previous studies suggested that TNF may contribute to heart failure progression, it is unclear whether antagonizing TNF is beneficial in heart failure patients.

METHODS AND RESULTS

Eighteen NYHA class III heart failure patients were randomized into a double-blind dose-escalation study to examine the safety and potential efficacy of etanercept, a specific TNF antagonist (Enbrel). Patients received placebo (6 patients) or an escalating dose (1, 4, or 10 mg/m2) of etanercept (12 patients) given as a single intravenous infusion. Safety parameters and patient functional status were assessed at baseline and at days 1, 2, 7, and 14. There were no significant side effects or clinically significant changes in laboratory indices. There was, however, a decrease in TNF bioactivity and a significant overall increase in quality-of-life scores, 6-minute walk distance, and ejection fraction in the cohort that received 4 or 10 mg/m2 of etanercept; there was no significant change in these parameters in the placebo group.

CONCLUSIONS

A single intravenous infusion of etanercept was safe and well tolerated in patients with NYHA class III heart failure. These studies provide provisional evidence that suggests that etanercept is sufficient to lower levels of biologically active TNF and may lead to improvement in the functional status of patients with heart failure.

An overview of tumor necrosis factor alpha and the failing human heart

Recent studies have identified the importance of biologically active molecules (e.g., neurohormones) in disease progression in heart failure. 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 suggest that the cytokines (e.g., tumor necrosis factor alpha), much like the neurohormones, may represent another class of biologically active molecules that are responsible for the development and progression of heart failure.

Medical and surgical therapy for cardiac remodeling

Ventricular remodeling refers to changes in ventricular geometry, volume, mass, and myocellular structure in response to myocardial injury or alteration in loading conditions. Although initially adaptive as a consequence of the initial damage to the myocardium, progressive ventricular remodeling is ultimately a maladaptive process that is associated with significant cardiovascular morbidity and mortality. Treatment with an aim to halt or reverse remodeling with mainly two classes of medications, angiotensin-converting enzyme inhibitors and beta-adrenergic blockers, has been shown to improve the long-term outcome. The role of pharmacologic and surgical therapy in remodeling is evolving and may have an important impact on the development of new directions of therapy for heart failure, myocardial infarction, and hypertension.

Thoracic CT findings in long-term hemodialysis patients

PURPOSE

To evaluate thoracic CT findings of long-term hemodialysis patients.

MATERIAL AND METHODS

Thoracic CT findings of 117 uremic patients (61 men, 56 women) with complaints of cough, dyspnea, low-grade pyrexia, malaise, weight loss, and profuse perspiration were retrospectively documented.

RESULTS

Atelectasis (60%), cardiomegaly (60%), pleural effusion (51%), vascular congestion (44%), parenchymal consolidation (38%), parenchymal scarring-fibrosis (31%), and lymphadenopathy (29%) were the most common CT findings in the thoraces of the long-term hemodialysis patients. Staphylococcus aureus was detected in 13 patients (11%) who had parenchymal infiltration. Thoracic tuberculosis was identified in 15 patients (13%), 11 of these cases being confined to the lung parenchyma, 3 to the pleura, and 1 involving the pleura and pericardium.

CONCLUSION

In patients under long-term hemodialysis treatment, parenchymal consolidation, secondary to infectious agents such as S. aureus and Mycobacterium tuberculosis, is the most important CT finding since these lesions can be detected and treated successfully if they are considered as etiologic factors early on.

Cardiac remodeling as a consequence and cause of progressive heart failure

Natural history studies in heart failure have shown that increases in left ventricular (LV) volume and LV mass are directly related to future deterioration in LV performance and a less favorable clinical course. Despite the recognized importance of remodeling in heart failure, very little is known about the basic mechanisms that lead to cardiac remodeling. In this review, we will summarize recent clinical and experimental studies that highlight the importance of the remodeling process during the progression of heart failure. The intent of this review is to provide an integrated view of the mechanisms that contribute to LV remodeling at the cellular level, the myocardial level, and the level of the chamber.

The role of cytokines in the failing human heart

Despite repeated attempts to develop a unifying hypothesis that explains the clinical syndrome of heart failure, no single conceptual paradigm has withstood the test of time. In this regard, recent studies have shown that a class of biologically active molecules, generically referred to as cytokines, are overexposed in heart failure. This article will review recent clinical and experimental material that suggest proinflammatory (stress activated) cytokines such as tumor necrosis factor-alpha (TFN-alpha), interleukin-1 (IL-1), and interleukin-6 (IL-6) may play a role in the pathogenesis of congestive heart failure. The scope of this article includes an overview of the biology of cytokines in the heart, as well as review of the clinical studies that have documented elevated levels of cytokines and cytokine receptors in patients with heart failure.

Pathophysiologically relevant concentrations of tumor necrosis factor-alpha promote progressive left ventricular dysfunction and remodeling in rats

BACKGROUND

Although patients with heart failure express elevated circulating levels of tumor necrosis factor-alpha (TNF-alpha) in their peripheral circulation, the structural and functional effects of circulating levels of pathophysiologically relevant concentrations of TNF-alpha on the heart are not known.

METHODS AND RESULTS

Osmotic infusion pumps containing either diluent or TNF-alpha were implanted into the peritoneal cavity of rats. The rate of TNF-alpha infusion was titrated to obtain systemic levels of biologically active TNF-alpha comparable to those reported in patients with heart failure (approximately 80 to 100 U/mL), and the animals were examined serially for 15 days. Two-dimensional echocardiography was used to assess changes in left ventricular (LV) structure (remodeling) and LV function. Video edge detection was used to assess isolated cell mechanics, and standard histological techniques were used to assess changes in the volume composition of LV cardiac myocytes and the extracellular matrix. The reversibility of cytokine-induced effects was determined either by removal of the osmotic infusion pumps on day 15 or by treatment of the animals with a soluble TNF-alpha antagonist (TNFR:Fc). The results of this study show that a continuous infusion of TNF-alpha led to a time-dependent depression in LV function, cardiac myocyte shortening, and LV dilation that were at least partially reversible by removal of the osmotic infusion pumps or treatment of the animals with TNFR:Fc.

CONCLUSIONS

These studies suggest that pathophysiologically relevant concentrations of TNF-alpha are sufficient to mimic certain aspects of the phenotype observed in experimental and clinical models of heart failure.

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.