Tumour necrosis factor in chronic heart failure: a peripheral view on pathogenesis, clinical manifestations and therapeutic implications

A Structural and Functional Perspective of Death Receptor 6

As a member of the tumor necrosis factor receptor superfamily (TNFRSF), death receptor 6 (DR6) has a similar structural architecture to other family members. The extracellular region of DR6 contains four cysteine-rich domains, followed by a single-pass transmembrane domain and an intracellular region. Since its discovery, DR6 has become an orphan receptor ubiquitously expressed to transduce unique signaling pathways. Although the free ectodomains of β-amyloid precursor protein (APP) can bind to DR6 to induce apoptotic signals, the natural ligands of DR6 still remain largely unknown. In this review, we focus on recent research progress of structural and functional studies on DR6 for better understanding DR6-mediated signaling and the treatment of DR6-related diseases.

Clinical Characteristics of De Novo Heart Failure and Acute Decompensated Chronic Heart Failure: Are They Distinctive Phenotypes That Contribute to Different Outcomes?

Heart failure is currently one of the leading causes of morbidity and mortality. Patients with heart failure often present with acute symptoms and may have a poor prognosis. Recent evidence shows differences in clinical characteristics and outcomes between de novo heart failure (DNHF) and acute decompensated chronic heart failure (ADCHF). Based on a better understanding of the distinct pathophysiology of these two conditions, new strategies may be considered to treat heart failure patients and improve outcomes. In this review, the authors elaborate distinctions regarding the clinical characteristics and outcomes of DNHF and ADCHF and their respective pathophysiology. Future clinical trials of therapies should address the potentially different phenotypes between DNHF and ADCHF if meaningful discoveries are to be made.

The use of aliskiren as an antifibrotic drug in experimental models: A systematic review

Aliskiren is an oral antihypertensive medication that acts by directly inhibiting renin. High levels of circulating renin and prorenin activate the pathological signaling pathway of fibrosis. This drug also reduces oxidative stress. Thus, the aim of this systematic review is to analyze experimental studies that show the actions of aliskiren on fibrosis. PubMed and LILACS databases were consulted using the keywords aliskiren and fibrosis within the period between 2005 and 2017. Fifty-three articles were analyzed. In the heart, aliskiren attenuated remodeling, hypertrophy, inflammatory cytokines, collagen deposition, and oxidative stress. In the kidneys, there was a reduction in interstitial fibrosis, the infiltration of inflammatory cells, apoptosis, proteinuria, and in the recruitment of macrophages. In diabetic models, an improvement in the albumin/creatinine relationship and in the insulin pathway in skeletal muscles was observed; aliskiren was beneficial to pancreatic function and glucose tolerance. In the liver, aliskiren reduced fibrosis, steatosis, inflammatory cytokines, and collagen deposition. In the lung and peritoneal tissues, there was a reduction in fibrosis. Many studies have reported on the beneficial effects of aliskiren on endothelial function and arterial rigidity. A reduction in fibrosis in different organs is cited by many authors, which complies with the results found in this review. However, studies diverge on the use of the drug in diabetic patients. Aliskiren has antifibrotic potential in several experimental models, interfering with the levels of fibrogenic cytokines and oxidative stress. Therefore, its use in diseases in which fibrosis plays an important pathophysiological role is suggested.

Functional Food and Cardiovascular Disease Prevention and Treatment: A Review

Cardiovascular disease (CVD) is now the leading cause of death globally and is a growing health concern. Lifestyle factors, including nutrition, play an important role in the etiology and treatment of CVD. Functional foods based on their basic nutritional functions can decrease the risk of many chronic diseases and have some physiological benefits. They contain physiologically active components either from plant or animal sources, marketed with the claim of their ability to reduce heart disease risk, focusing primarily on established risk factors, which are hyperlipidemia, diabetes, metabolic syndrome, obesity/overweight, elevated lipoprotein A level, small dense low-density lipoprotein cholesterol (LDL-C), and elevated inflammatory marker levels. Functional foods are suspected to exert their cardioprotective effects mainly through blood lipid profile level and improve hypertension control, endothelial function, platelet aggregation, and antioxidant actions. Clinical and epidemiological observations indicate that vegetable and fruit fiber, nuts and seeds, sea foods, coffee, tea, and dark chocolate have cardioprotective potential in humans, as well whole-grain products containing intact grain kernels rich in fiber and trace nutrients. They are nutritionally more important because they contain phytoprotective substances that might work synergistically to reduce cardiovascular risk. This review will focus on the reciprocal interaction between functional foods and the potential link to cardiovascular health and the possible mechanisms of action.

Are different stoichiometries feasible for complexes between lymphotoxin-alpha and tumor necrosis factor receptor 1?

Background

Tumor necrosis factors, TNF and lymphotoxin-α (LT), are cytokines that bind to two receptors, TNFR1 and TNFR2 (TNF-receptor 1 and 2) to trigger their signaling cascades. The exact mechanism of ligand-induced receptor activation is still unclear. It is generally assumed that three receptors bind to the homotrimeric ligand to trigger a signaling event. Recent evidence, though, has raised doubts if the ligand:receptor stoichiometry should indeed be 3:3 for ligand-induced cellular response. We used molecular dynamics simulations, elastic network models, as well as MM/PBSA to analyze this question.

Results

Applying MM/PBSA methodology to different stoichiometric complexes of human LT-(TNFR1)_n=1,2,3 the free energy of binding in these complexes has been estimated by single-trajectory and separate-trajectory methods. Simulation studies rationalized the favorable binding energy in the LT-(TNFR1)₁ complex, as evaluated from single-trajectory analysis to be an outcome of the interaction of cysteine-rich domain 4 (CRD4) and the ligand. Elastic network models (ENMs) help to associate the difference in the global fluctuation of the receptors in these complexes. Functionally relevant transformation associated with these complexes reveal the difference in the dynamics of the receptor when free and in complex with LT.

Conclusions

MM/PBSA predicts complexes with a ligand-receptor molar ratio of 3:1 and 3:2 to be energetically favorable. The high affinity associated with LT-(TNFR1)₁ is due to the interaction between the CRD4 domain with LT. The global dynamics ascertained from ENMs have highlighted the differential dynamics of the receptor in different states.

Xanthine oxidase and uric acid in cardiovascular disease: clinical impact and therapeutic options

The association between increased uric acid (UA) levels and cardiovascular disease (CVD) has been observed and studied for many decades. The value of UA as an independent factor within the metabolic risk profile for prediction of CVD in the normal population remains an issue of ongoing discussion. In turn, increasing evidence suggests that among patients with established CVD such as heart failure UA is an independent marker of disease state and prognosis. Increased UA levels may be an indicator of up-regulated activity of xanthine oxidase, a powerful oxygen radical-generating system in human physiology. Increased reactive oxygen species (ROS) accumulation contributes to endothelial dysfunction, metabolic and functional impairment, inflammatory activation, and other features of cardiovascular pathophysiology. Accordingly, inhibition of xanthine oxidase activity has been shown to improve a range of surrogate markers in patients with CVD, but this effect seems to be confined to hyperuricemic patients because disappointing results were reported in studies with normouricemic patients. In this review we summarize current evidence on hyperuricemia in CVD. The value of UA as a biomarker and as a potential therapeutic target for tailored metabolic treatment in CVD is discussed.

TNFα in myocardial ischemia/reperfusion, remodeling and heart failure

TNFα is crucially involved in the pathogenesis and progression of myocardial ischemia/reperfusion injury and heart failure. The formation and release of TNFα and its downstream signal transduction cascade following activation of its two receptor subtypes are characterized. Myocardial TNFα and TNF receptor activation have an ambivalent role in myocardial ischemia/reperfusion injury and protection from it. Excessive TNFα expression and subsequent cardiomyocyte TNF receptor type 1 stimulation induce contractile dysfunction, hypertrophy, fibrosis and cell death, while a lower TNFα concentration and subsequent cardiomyocyte TNF receptor type 2 stimulation are protective. Apart from its concentration and receptor subtype, the myocardial action of TNFα depends on the duration of its exposure and its localization. While detrimental during sustained ischemia, TNFα contributes to ischemic preconditioning protection, no matter whether it is the first, second or third window of protection, and both TNF receptors are involved in the protective signal transduction cascade. Finally, the available clinical attempts to antagonize TNFα in cardiovascular disease, notably heart failure, are critically discussed.

Association of amino-terminal pro-brain natriuretic peptide with metabolic syndrome

OBJECTIVE

This study evaluated the relationship between individual components in metabolic syndrome (MetS) and amino-terminal pro-brain natriuretic peptide (NT-proBNP).

METHODS

A screening program for MetS in 2008 in Taiwan excluded subjects aged <30 years and pregnant women. Fasting glucose, insulin level, high-sensitivity C-reactive protein (hsCRP), and NT-proBNP were assessed. A propensity-score matching process was used to select subjects with and without MetS comparable in age, gender, body height, and serum creatinine levels. A multiple regression model was used to determine the association between individual components of MetS and NT-proBNP. Finally 270 subjects with MetS and another 270 matched subjects without MetS aged ≥30 years were included.

RESULTS

The subjects with MetS had higher uric acid and hsCRP, but not NT-proBNP. Multiple regression model showed that log (NT-proBNP) was positively associated with systolic blood pressure (β=0.002 per mmHg, p=0.013), but negatively associated with body mass index (β=-0.017 per kg/m(2), p=0.018), triglyceride (β=-0.00048 per mg/dL, p=0.020) and insulin level (β=-0.005 per mU/L, p=0.005). Log (NT-proBNP) was neutral to waist circumference, fasting glucose, high-density lipoprotein cholesterol, and diastolic blood pressure.

CONCLUSION

MetS was not associated with serum NT-proBNP concentrations due to the contradictory effects of each component.

The role of magnesium deficiency in cardiovascular and intestinal inflammation

Hypomagnesemia continues to cause difficult clinical problems, such as significant cardiac arrhythmias where intravenous magnesium therapy can be lifesaving. Nutritional deficiency of magnesium may present with some subtle symptoms such as leg cramps and occasional palpitation. We have investigated dietary-induced magnesium deficiency in rodent models to assess the pathobiology associated with prolonged hypomagnesemia. We found that neuronal sources of the neuropeptide, substance P (SP), contributed to very early prooxidant/proinflammatory changes during Mg deficiency. This neurogenic inflammation is systemic in nature, affecting blood cells, cardiovascular, intestinal, and other tissues, leading to impaired cardiac contractility similar to that seen in patients with heart failure. We have used drugs that block the release of SP from neurons and SP-receptor blockers to prevent some of these pathobiological changes; whereas, blocking SP catabolism enhances inflammation. Our findings emphasize the essential role of this cation in preventing cardiomyopathic changes and intestinal inflammation in a well-studied animal model, and also implicate the need for more appreciation of the potential clinical relevance of optimal magnesium nutrition and therapy.

Whole grape intake impacts cardiac peroxisome proliferator-activated receptor and nuclear factor kappaB activity and cytokine expression in rats with diastolic dysfunction

Prolonged hypertension is the leading cause of heart failure. Failing hearts show reduced peroxisome proliferator-activating receptor (PPAR) activity and enhanced nuclear factor kappaB (NF-kappaB) activity, which together modify cardiac inflammation and fibrosis. In vitro studies suggest that phytochemicals alter PPAR and NF-kappaB activity, but the capabilities of a phytochemical-rich diet are less understood. Grapes contain an array of commonly consumed dietary phytochemicals. In Dahl salt-sensitive hypertensive rats, we showed previously that dietary provision of whole table grape powder (3% weight:weight) for 18 weeks reduced blood pressure, cardiac hypertrophy, and diastolic dysfunction. The hypothesis tested here is that, in this model, phytochemical provision from whole grape powder impacts cardiac PPAR and NF-kappaB activity and their related gene transcripts. Grape-fed rats had enhanced PPAR-alpha and PPAR-gamma DNA binding activity but reduced NF-kappaB DNA binding activity. RT-PCR revealed that grape-fed rats showed upregulated mRNA for PPAR-alpha, PPAR-gamma coactivator-1alpha, PPAR-gamma, and the cytosolic NF-kappaB inhibitor, inhibitor-kappaBalpha. By contrast, grape-fed rats showed downregulated mRNA for tumor necrosis factor-alpha and transforming growth factor-beta1. Finally, grape-fed rats showed significantly reduced cardiac tumor necrosis factor-alpha and transforming growth factor-beta protein expression, increased inhibitor-kappaBalpha expression, and reduced cardiac fibrosis. In the Dahl salt-sensitive rat, chronic intake of grapes altered cardiac transcripts related to PPAR and NF-kappaB that may be significant to the observed diet-associated cardioprotection.

Biomarkers for chronic heart failure : diagnostic, prognostic, and therapeutic challenges

Cardiac biomarkers are very important in diagnosis, risk stratification, and management of patients with heart failure. Although not meeting all criteria for an ideal biomarker, natriuretic peptides primarily have a diagnostic and prognostic role. Other routinely available and newly emerging biomarkers have a complementary role in patient management; thus multimarker strategy might be warranted in future. The quest for a single marker or a combination is ongoing and several established, widely available biomarkers might have been overlooked in the field of heart failure. The authors review some of those biomarkers and speculate on the possible roles of combining two or more of them.

Cardiac cachexia: a systematic overview

Cardiac cachexia as a terminal stage of chronic heart failure carries a poor prognosis. The definition of this clinical syndrome has been a matter of debate in recent years. This review describes the ongoing discussion about this issue and the complex pathophysiology of cardiac cachexia and chronic heart failure with particular focus on immunological, metabolic, and hormonal aspects at the intracellular and extracellular level. These include regulators such as neuropeptide Y, leptin, melanocortins, ghrelin, growth hormone, and insulin. The regulation of feeding is discussed as are nutritional aspects in the treatment of the disease. The mechanisms of wasting in different body compartments are described. Moreover, we discuss several therapeutic approaches. These include appetite stimulants like megestrol acetate, medroxyprogesterone acetate, and cannabinoids. Other drug classes of interest comprise angiotensin-converting enzyme inhibitors, beta-blockers, anabolic steroids, beta-adrenergic agonists, anti-inflammatory substances, statins, thalidomide, proteasome inhibitors, and pentoxifylline.

Nuclear factor-kappa B signaling in skeletal muscle atrophy

Skeletal muscle atrophy/wasting is a serious complication of a wide range of diseases and conditions such as aging, disuse, AIDS, chronic obstructive pulmonary disease, space travel, muscular dystrophy, chronic heart failure, sepsis, and cancer. Emerging evidence suggests that nuclear factor-kappa B (NF-kappaB) is one of the most important signaling pathways linked to the loss of skeletal muscle mass in various physiological and pathophysiological conditions. Activation of NF-kappaB in skeletal muscle leads to degradation of specific muscle proteins, induces inflammation and fibrosis, and blocks the regeneration of myofibers after injury/atrophy. Recent studies employing genetic mouse models have provided strong evidence that NF-kappaB can serve as an important molecular target for the prevention of skeletal muscle loss. In this article, we have outlined the current understanding regarding the role of NF-kappaB in skeletal muscle with particular reference to different models of muscle wasting and the development of novel therapy.

Role of p38 mitogen-activated protein kinase pathway on heart failure in the infant rat after burn injury

We examined the hypothesis that post-burn activation of the p38 mitogen-activated protein kinase (MAPK) pathway is one aspect of the signalling cascade culminating in post-burn secretion of tumour necrosis factor (TNF)-alpha which contributes to post-burn myocardial apoptosis. Studies were designed to determine the time course of the induction of p38MAPK, TNF-alpha and myocardial apoptosis after burn injury. Our quantitative bacterial culture data demonstrated that viable bacteria reached the heart, and Western blotting data identified the increase in the phosphorylation of p38MAPK at an early time after burn. The peak incidence of myocardial apoptosis was also seen at an early time after burn. The expression of TNF-alpha mRNA, infiltrated neutrophils and serum creatine phosphokinase myocardial band data peaked at a late time after burn. FR167653, a specific inhibitor of p38MAPK, prevented the induction of myocardial apoptosis, TNF-alpha expression and myocardial injury after burn. Presumably, the bacterial LPS-induced activation of p38MAPK pathway occurring at an early time after burn induced the subsequent myocardial apoptosis. The p38MAPK-induced activation of pro-inflammatory cytokine appeared to promote the degenerative myocardial injury at a late time after burn. Our present data provided evidence for the hypothesis that the p38MAPK pathway controls both myocardial apoptosis and the pro-inflammatory mediator.

Cytokines and anti-cytokines as therapeutics--an update

Cytokines which comprise of a family of proteins--interleukins, lymphokines, monokines, interferons, and chemokines, are important components of the immune system. They act in concert with specific cytokine inhibitors and soluble cytokine receptors to regulate the human immune response. Their physiologic role in inflammation and pathologic role in systemic inflammatory states are now well recognized. An imbalance in cytokine production or cytokine receptor expression and/or dysregulation of a cytokine process contributes to various pathological disorders. Research is progressing rapidly in the area of cytokines and their therapeutic targets, the two major therapeutic modalities being the administration of purified recombinant cytokines and the use of their antagonists in various inflammatory disorders. However, given the large number of cytokines, it is disappointing that only relatively few can be used clinically. In the present article, we have made an attempt to review and present a glimpse of the history as well as up to date information that is pertinent to cytokines and anti-cytokine therapies in the treatment of cancer, autoimmune disorders and various other related diseases.

ROLE OF BACTERIAL ENDOTOXIN IN CHRONIC HEART FAILURE

Proinflammatory cytokines are now thought to play a key role in the pathophysiology of chronic heart failure, driving both symptomatic presentation and disease progression. We propose that this proinflammatory state, in turn, may be sustained through a chronic release of enterically derived bacterial endotoxin. Human trials have indicated that bacterial decontamination of the gut with concomitant decrease in lipopolysaccharide (LPS) has a positive outcome on heart disease patients. Antiendotoxin antibodies may thus represent therapeutic agents in this setting. Previously, antiendotoxin antibodies were targeted to the inner hydrophobic lipid A moiety of endotoxin in an attempt to neutralize its toxicity. These antibodies failed because they lacked specificity and bound to LPS weakly. In contrast, our studies on antiendotoxin antibodies have revealed that antibodies targeted to the hydrophilic oligosaccharides of the endotoxin have the potential to bind specifically with high affinity. Development of immunotherapeutics that can reduce systemic LPS or other agents, such as bactericidal/permeability-increasing protein that can neutralize LPS and limit inflammation safely, will enable the role of LPS in chronic heart failure to be elucidated and may pave the way to develop a new generation of effective therapeutic agents that may be directed to the treatment of chronic heart failure.

Immune status evaluation of patients with chronic heart failure

Chronic heart failure (CHF) may be considered a state of immune activation and persistent inflammation expressed by increased circulating levels of pro- and anti-inflammatory cytokines. The purpose of the study was to investigate the immune status in patients with CHF compared to normal individuals. We measured serum cytokine levels as well as cytokine production after ex vivo LPS stimulation of whole blood taken from 14 patients with CHF and 14 healthy volunteers. We used 500 pg/ml of LPS for an incubation period of 4h to stimulate 100 microL of whole blood. Patients with CHF had significantly higher levels of TNF-RI, and TNF-RII in serum compared to normal individuals. TNF-alpha, IL-6, and IL-10 did not differ significantly. After LPS stimulation, patients with CHF had significantly higher levels of TNF-alpha and IL-10, and significantly lower IL-6 levels compared to normal individuals. TNF-alpha receptors did not differ significantly. Patients with CHF may be found in a pro- as well as an anti-inflammatory state. They also do not develop endotoxin tolerance in an ex vivo laboratory model using whole blood stimulated with LPS. They may have increased TNF-alpha and IL-10 production after LPS stimulation of whole blood, which may contribute to a worsening of heart function, more severe disease presentation and a worse outcome during infections.

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.

The nerve-heart connection in the pro-oxidant response to Mg-deficiency

Magnesium is a micronutrient essential for the normal functioning of the cardiovascular system, and Mg deficiency (MgD) is frequently associated in the clinical setting with chronic pathologies such as CHF, diabetes, hypertension, and other pathologies. Animal models of MgD have demonstrated a systemic pro-inflammatory/pro-oxidant state, involving multiple tissues/organs including neuronal, hematopoietic, cardiovascular, and gastrointestinal systems; during later stages of MgD, a cardiomyopathy develops which may result from a cascade of inflammatory events. In rodent models of dietary MgD, a significant rise in circulating levels of proinflammatory neuropeptides such as substance P (SP) and calcitonin gene-related peptide among others, was observed within days (1-7) of initiating the Mg-restricted diet, and implicated a neurogenic trigger for the subsequent inflammatory events; this early "neurogenic inflammation" phase may be mediated in part, by the Mg-gated N: -methyl-D-aspartate (NMDA) receptor/channel complex. Deregulation of the NMDA receptor may trigger the abrupt release of neuronal SP from the sensory-motor C-fibers to promote the subsequent pro-inflammatory changes: elevations in circulating inflammatory cells, inflammatory cytokines, histamine, and PGE(2) levels, as well as formation of nitric oxide, reactive oxygen species, lipid peroxidation products, and depletion of key endogenous antioxidants. Concurrent elevations of tissue CD14, a high affinity receptor for lipopolyssacharide, suggest that intestinal permeability may be compromised leading to endotoxemia. If exposure to these early (1-3 weeks MgD) inflammatory/pro-oxidant events becomes prolonged, this might lead to impaired cardiac function, and when co-existing with other pathologies, may enhance the risk of developing chronic heart failure.

Interaction between tumor necrosis factor-alpha and leptin-induced inhibition of cardiac contractile function in isolated ventricular myocytes

Pro-inflammatory factors such as the adipokine leptin and cytokine tumor necrosis factor-alpha (TNFalpha) have been implicated in the onset of myocardial dysfunction in ischemia-reperfusion injury, sepsis, heart failure, viral myocarditis and cardiac allograft rejection. Although circulating TNFalpha and leptin levels are both elevated under a variety of inflammatory conditions, it remains unknown whether TNFalpha and leptin depress cardiac contractile function independently or synergistically. We examined the effect of acute (30 min) and short-term (24h) exposure of TNFalpha, leptin or both on cardiac contractile function in adult rat ventricular myocytes. Contractile properties were evaluated using an Ionoptix Softedge system including peak shortening (PS), maximal velocity of shortening/relengthening (+/-L/t), time-to-PS (TPS) and time-to-90% relengthening (TR(90)). Both TNFalpha (0.5-500 pg/ml) and leptin (1-100 nm) exerted concentration-dependent inhibitions in PS and +/-L/t following a 30-min exposure. TNFalpha but not leptin prolonged TR(90). Interestingly, TNFalpha-induced depression of cell shortening was masked by leptin and vice versa. Following a 24-h incubation, both TNFalpha and leptin significantly inhibited PS and +/-L/t without affecting TPS and TR(90). There was no additive or synergistic response by the two pro-inflammatory factors. The nitric oxide synthase inhibitor l-NMMA abolished depression of myocyte shortening elicited by TNFalpha, leptin or both. In summary, this study demonstrated that the inhibitory effect on cardiac contraction by TNFalpha and leptin may mask each other and share a common mechanism(s), probably dependent on NO.

Uric acid in chronic heart failure

The pathophysiologic understanding of chronic heart failure (CHF) has shifted from a mere hemodynamic disorder to a much more complex approach including changes and imbalances in neurohormonal, immune, and metabolic functions. Among metabolic abnormalities, hyperuricemia is a constant finding in CHF. The xanthine oxidase metabolic pathway increasingly is appreciated as an important contributor to both symptoms of CHF as well as progression of the disease. Recent data suggest hyperuricemia to be an independent marker of impaired prognosis in CHF. In this article, the significance of the xanthine oxidase metabolic pathway in CHF is discussed. Data on xanthine oxidase inhibition are reviewed, which suggest a beneficial effect of therapeutically targeting this enzymatic pathway.

Xanthine oxidase inhibition for chronic heart failure: is allopurinol the next therapeutic advance in heart failure?

A substantial body of evidence has accumulated to suggest a role for the xanthine oxidase metabolic pathway in the pathophysiology of chronic heart failure and other cardiovascular diseases.

Wasting of the left ventricle in patients with cardiac cachexia: a cardiovascular magnetic resonance study

BACKGROUND

The "cachectic heart" has been described as a pathologic decrease in the size and mass of the heart, but no in vivo studies have shown changes in cardiac dimensions or left ventricular (LV) mass over time in chronic heart failure (CHF) associated with body wasting (cardiac cachexia). Cardiovascular magnetic resonance (CMR) has high reproducibility and is more sensitive than other techniques.

METHODS

CMR studies of LV volumes and mass were performed at baseline and a mean of 15 months later in nine CHF patients with cardiac cachexia and 28 matched CHF controls without cachexia (mass index 23 +/- 1 vs. 29 +/- 5 kg/m2, P=0.0005).

RESULTS

At baseline, LV end-diastolic volume (197 +/- 78 vs. 203 +/- 65 ml), end-systolic volume (131 +/- 75 vs. 126 +/- 63 ml), LV mass (213 +/- 44 vs. 222 +/- 62 g), and LV ejection fraction (38 +/- 19% vs. 40 +/- 16%) did not differ between cachectic patients and controls (all P>0.10). During follow-up, there was a significant decrease in LV mass in patients with cachexia (-16 g, P<0.05) and a trend to increase in LV mass in patients without cachexia (+7 g, P=0.12, comparison between groups: P=0.010).

CONCLUSIONS

The direction of changes over time in LV mass differs in CHF patients with cachexia as compared with non-cachectic controls. A significant decrease in LV mass occurs in patients with cardiac cachexia. This study documents in vivo the occurrence of wasting of the left ventricle in patients with CHF who demonstrate general body wasting.

Pentoxifylline in ischemic, hypertensive and idiopathic-dilated cardiomyopathy: effects on left-ventricular function, inflammatory cytokines and symptoms

INTRODUCTION

Tumor necrosis factor (TNF)-alpha and interleukin-6 (IL-6) are significantly elevated in patients with congestive heart failure (CHF). Pentoxifylline, a xanthin-derived agent, is known to inhibit the production of TNF-alpha and IL-6. Recent studies have shown that pentoxifylline produces an increase in ejection fraction, a decrease in left-ventricular chamber size and an improvement in clinical status in patients with idiopathic-dilated cardiomyopathy. Therefore, we studied the effects of pentoxifylline in ischemic, hypertensive and idiopathic-dilated cardiomyopathy.

METHODS

Primary endpoint was left-ventricular ejection fraction (LVEF) assessed by contrast 2D echocardiography. Secondary endpoints were concentrations of TNF-alpha, IL-6, brain natriuretic peptide, maximal oxygen uptake (VO(2 max)) assessed by cardiopulmonary exercise testing and Minnesota Living with Heart Failure Questionnaire score or New York Heart Association scale.

RESULTS

Forty-seven patients (31.9% ischemic, 21.3% hypertensive, 10.6% ischemic and hypertensive, 36.2% idiopathic-dilated cardiomyopathy) were randomly assigned to pentoxifylline 600 mg BID (n=23) or placebo (n=24) if they had a compensated CHF with a LVEF less than or equal to 40% and had taken their standard treatment consisting of angiotensin-converting enzyme inhibitors, diuretics and beta-blockers for at least 3 months. Baseline demographic and clinical characteristics of each group were similar. Forty-one patients completed the study protocol and were analysed for primary and secondary endpoints. After 6 months of treatment, LVEF was unchanged in the pentoxifylline group compared with placebo (29+/-7 to 33+/-10% vs. 27+/-9 to 34+/-9%, respectively, P=NS). Also the secondary endpoints did not significantly change during follow-up.

CONCLUSION

Additional treatment with pentoxifylline is neutral with regard to left-ventricular function, inflammatory cytokines and symptoms in patients with ischemic, hypertensive and idiopathic-dilated cardiomyopathy.

Studies on intragastric PCO2at rest and during exercise as a marker of intestinal perfusion in patients with chronic heart failure

AIMS

The aim of this study was to investigate mesenteric ischaemia by determining intragastric PCO(2) (iPCO(2)) with gastric tonometry during rest and exercise stress testing in patients with chronic heart failure (CHF). In CHF inflammatory immune activation is hypothesized to result from a chronic endotoxin challenge due to bacterial translocation of hypoperfused intestinal mucosa.

METHODS AND RESULTS

In 10 patients with CHF and ten healthy controls a tonometry catheter was inserted into the stomach. IPCO(2) was measured at rest and during bicycle exercise every 5 min. At rest arterial pCO(2) (aPCO(2)), intragastric pCO(2) (iPCO(2)) and the intragastric/arterial gap did not differ between patients and controls. During low level exercise (25 W), patients showed an increase in iPCO(2) compared to resting iPCO(2), whereas controls did not show an increase in iPCO(2) (change in iPCO(2): 12+/-2% vs. 1+/-0.4%, P<0.001). In CHF, iPCO(2) during peak exercise was 25+/-3% higher than at rest, compared to controls (increase 2+/-1, P<0.0001).

CONCLUSIONS

Patients with CHF already at low level exercise develop an increase in iPCO(2). This is likely to reflect hypoperfusion of the intestinal mucosa, which may contribute to the development of bacterial translocation.

Tumor necrosis factor receptors 1 and 2 differentially regulate survival, cardiac dysfunction, and remodeling in transgenic mice with tumor necrosis factor-alpha-induced cardiomyopathy

BACKGROUND

Tumor necrosis factor (TNF)-alpha plays a pathophysiological role in heart failure. Although both TNF receptor 1 (TNFR1) and 2 (TNFR2) are present in the heart, comparatively little is known about the role of TNFR2.

METHODS AND RESULTS

We bred TNFR1-knockout (KO) or TNFR2KO mice to transgenic (TG) mice with cardiac-specific overexpression of TNF-alpha and analyzed resultant progeny. Six groups of male and female mice were studied: wild type (WT) with wild receptors (WT/W), TG with wild receptors (TG/W), TG with heterozygous receptor KO (TG/R1+/- or TG/R2+/-), and TG with homozygous receptor KO (TG/R1-/- or TG/R2-/-). Both male and female TG mice displayed cardiac hypertrophy, dilation, and reduced cardiac function. Male TG mice were more severely affected than genotypically matched females and died of heart failure at a younger age. Survival, cardiac function, and remodeling of TG/R1+/- and TG/R1-/- mice were improved relative to TG/W mice in both males and females. However, the survival of female TG/R2+/- and TG/R2-/- mice was worse than that of TG/W mice, with increased left ventricular dimension and left ventricular weight/body weight ratios. The cardiac TNF-alpha protein level was upregulated in TG/R1-/- and TG/R2-/- compared with TG/W mice, whereas the level of TNF receptors was not downregulated in TG/W relative to WT/W mice.

CONCLUSIONS

Ablation of the TNFR2 gene exacerbates heart failure and reduces survival, whereas ablation of TNFR1 blunts heart failure and improves survival. Signaling via TNFR2 may play a cardioprotective role in the pathogenesis of cytokine-mediated heart failure.

Glutamate synthase: a fascinating pathway from L-glutamine to L-glutamate

Glutamate synthase is a multicomponent iron-sulfur flavoprotein belonging to the class of N-terminal nucleophile amidotransferases. It catalyzes the conversion of L-glutamine and 2-oxoglutarate into two molecules of L-glutamate. In recent years the X-ray structures of the ferredoxin-dependent glutamate synthase and of the a subunit of the NADPH-dependent glutamate synthase have become available. Thanks to X-ray crystallography, it is now known that the ammonia reaction intermediate is transferred via an intramolecular tunnel from the amidotransferase domain to the synthase domain over a distance of about 32A. Although ammonia channeling is a recurrent theme for N-terminal nucleophile and triad-type amidotransferases, the molecular mechanisms of ammonia transfer and its control are different for each known amidotransferase. This review focuses on the intriguing mechanism of action and self-regulation of glutamate synthase with a special focus on the structural data.

Cardiac cachexia

Chronic heart failure (CHF) remains an important and increasing public health care problem. It is a complex syndrome affecting many body systems. Body wasting (i.e., cardiac cachexia) has long been recognised as a serious complication of CHF. Cardiac cachexia is associated with poor prognosis, independently of functional disease severity, age, and measures of exercise capacity and cardiac function. Patients with cardiac cachexia suffer from a general loss of fat tissue, lean tissue, and bone tissue. Cachectic CHF patients are weaker and fatigue earlier, which is due to both reduced skeletal muscle mass and impaired muscle quality. The pathophysiologic alterations leading to cardiac cachexia remain unclear, but there is increasing evidence that metabolic, neurohormonal and immune abnormalities may play an important role. Cachectic CHF patients show raised plasma levels of epinephrine, norepinephrine, and cortisol, and they show high plasma renin activity and increased plasma aldosterone level. Several studies have also shown that cardiac cachexia is linked to raised plasma levels of tumour necrosis factor alpha and other inflammatory cytokines. The degree of body wasting is strongly correlated with neurohormonal and immune abnormalities. The available evidence suggests that cardiac cachexia is a multifactorial neuroendocrine and metabolic disorder with a poor prognosis. A complex imbalance of different body systems may cause the development of body wasting.

The aminotetraline derivative (+/-)-(R,S)-5,6-dihydroxy-2-methylamino-1,2,3,4-tetrahydro-naphthalene hydrochloride (CHF-1024) displays cardioprotection in postischemic ventricular dysfunction of the rat heart

To analyze the protective effects of the aminotetraline derivative (+/-)-(R,S)-5,6-dihydroxy-2-methylamino-1,2,3,4-tetrahydro-naphthalene hydrochloride (CHF-1024), a compound endowed with DA2-dopaminergic/alpha2-adrenergic receptor agonistic activity, in myocardial ischemia/reperfusion damage. A model of isolated and perfused (15 ml/min) electrically driven (300 beats/min) rat heart subjected to global ischemia (1 ml/min for 20 min) and reperfusion (15 ml/min for 30 min) was followed. Cardiac mechanics changes were evaluated together with biochemical markers of cardiac ischemia in perfusate and tissue tumor necrosis factor-alpha (TNF-alpha). CHF-1024, perfused through the heart for 15 min before ischemia at different molar concentrations (1-100 nM), significantly improved left ventricle developed pressure during reperfusion, and normalized left ventricular end-diastolic pressure and coronary perfusion pressure. This anti-ischemic effect of CHF-1024 was associated to a decrease in creatine kinase and lactate dehydrogenase, both released during heart reperfusion. These events were concomitant with maintenance of a higher production of 6-keto-prostaglandin F1alpha The ability of CHF-1024 to improve postischemic ventricular dysfunction was correlated with a dose-dependent inhibition of the release of both norepinephrine (NE), from sympathetic nerve endings, and TNF-alpha from cardiac tissue. The effect of CHF-1024 on NE release was almost completely antagonized by specific antagonists of presynaptic inhibitory receptors domperidone and rauwolscine. The finding that this new aminotetraline derivative possesses anti-ischemic properties and limits NE release from cardiac nerve endings may bear some therapeutic potential in cardiovascular diseases.

Signalling pathways of the TNF superfamily: a double-edged sword

Two different tumour-necrosis factors (TNFs), first isolated in 1984, were found to be cytotoxic to tumour cells and to induce tumour regression in mice. Research during the past two decades has shown the existence of a superfamily of TNF proteins consisting of 19 members that signal through 29 receptors. These ligands, while regulating normal functions such as immune responses, haematopoiesis and morphogenesis, have also been implicated in tumorigenesis, transplant rejection, septic shock, viral replication, bone resorption, rheumatoid arthritis and diabetes; so indicating their role as 'double-edged swords'. These cytokines either induce cellular proliferation, survival, differentiation or apoptosis. Blockers of TNF have been approved for human use in treating TNF-linked autoimmune diseases in the United States and other countries.

The relationship between age and production of tumour necrosis factor-alpha in healthy volunteers and patients with chronic heart failure

BACKGROUND

Ageing is associated with an altered immune response. Elevated plasma levels of tumour necrosis factor-alpha (TNF-alpha) are present in patients with advanced chronic heart failure (CHF). However, the relationship between age and the immune response in CHF is unknown.

METHODS

We investigated the relationship between age and the TNF-alpha generating capacity of lipopolysaccharide (LPS) stimulated peripheral blood mononuclear cells (PBMC) in nine healthy control subjects (mean age 51.6+/-3.6 years, age range 39-75 years) and 22 stable patients with CHF (mean age 68.3+/-1.5 years, age range 52-78 years, NYHA class 3.0+/-0.2). We also tested the TNF-alpha generating capacity of all control subjects and 18 CHF patients in whole blood cultures.

RESULTS

Subjects were subgrouped according to baseline TNF-alpha secretion in PBMC cultures into low- and high-responders, with the latter producing TNF-alpha even without LPS stimulation. High-responders produced more TNF-alpha than low-responders at all LPS doses (0.001-10 ng/ml, P<0.0001, repeated measures ANOVA), and high-responders were significantly older than low-responders (controls: 65.8+/-9.2 vs. 47.5+/-2.5 years; patients: 71.9+/-1.9 vs. 65.9+/-1.9 years, both P<0.05). Age correlated with TNF-alpha production in both patients and controls. This effect was independent of NYHA class.

CONCLUSIONS

LPS-responsiveness appears to relate to age in both healthy controls and CHF patients. When assessing the immune status of CHF patients, age should therefore be considered an important confounding factor. In whole blood these findings could only be confirmed at the highest LPS concentration used, thus suggesting that certain factors in the blood may be able to abolish LPS activity at lower concentrations.

Heart failure as an inflammatory condition: potential role for androgens as immune modulators

Heart failure has traditionally been considered a disease of the myocardium, with symptoms arising from altered haemodynamics. However, it is now recognised that, in addition to marked neuroendocrine disturbance, there is perturbation of cytokine expression in patients with heart failure, resulting in an inflammatory imbalance. This not only influences symptoms, but also plays a central role in the underlying pathophysiological processes of heart failure, leading to disease progression and poorer prognosis. Recognition of the influence of cytokines, in particular tumour necrosis factor, has opened a new avenue for potential therapies for heart failure. Current approaches involve immunomodulation, aimed at suppressing tumour necrosis factor. We suggest that androgens may potentially offer a superior therapeutic strategy by their well-recognised non-specific immunosuppressive and anti-inflammatory effects. Studies of cell lines, human mononuclear cells and animals in vivo have demonstrated the 'anti-cytokine' actions of androgens, and we have found a similar action in whole blood from patients with heart failure. These effects, along with the anabolic action of these agents, make androgens an attractive potential option for treatment of patients with heart failure.

How to RECOVER from RENAISSANCE? The significance of the results of RECOVER, RENAISSANCE, RENEWAL and ATTACH

Two trial programmes testing an anti-cytokine medication in chronic heart failure (CHF) have been halted. In the RENAISSANCE and RECOVER trials (the combined analysis being termed RENEWAL), 2048 CHF patients were randomised to placebo or one of 3 doses of etanercept, a fusion protein directed against TNF. Within RENAISSANCE and RECOVER a clinical composite score was used to assess the clinical effects at 24 weeks (primary endpoint: alpha 0.04). Overall, the number of patients who were classified to have during the trial "improved", remained "unchanged" or "worsened" was similar for patients on placebo or any dose of etanercept (RENAISSANCE: p=0.17, RECOVER: p=0.34). In RENEWAL (combined analysis of medium and high dose etanercept vs. placebo), the primary endpoint (death or CHF hospitalisation, alpha 0.01) was not different between etanercept and placebo (RR 1.10, 95%CI 0.91 to 1.33, p=0.33). In RENEWAL, the secondary endpoint (death for any cause) was not different between etanercept and placebo (RR 1.13, 95%CI 0.86 to 1.50, p=0.39). ATTACH was a phase II, multicentre, randomised, double-blind, placebo-controlled pilot trial that aimed to evaluate the effects of infliximab (an antibody against TNF given in 2 different doses) in 150 CHF patients with stable NYHA class III or IV (in NYHA IV: <10%). In the placebo group (n=49), none of the patients died during 28 weeks of follow-up. At 14 (28) weeks, the endpoint of death or hospitalisation was reached in 2 (5) patients on placebo, in 2 (4) patients in the medium dose (5 mg/kg), and in 8 (13) patients in the high dose (10 mg/kg) of infliximab. During follow-up, compared to placebo the hazard to reach this endpoint was similar in the medium dose group (RR 0.80, 95%CI 0.22-2.99), but increased in the high dose group (RR 2.84, 95%CI 1.01-7.97, p<0.05).

CONCLUSION

At the respective lower doses there was no safety issue with regards to the use of either infliximab or etanercept. High dose anti-TNF therapy may not be useful in CHF patients, but the situation in lower doses and in patients with documented inflammatory/metabolic problems or in cardiac cachexia has not yet been adequately assessed.

The syndrome of cardiac cachexia

Cachexia, i.e. body wasting, has long been recognised as a serious complication of chronic illness. The occurrence of wasting in chronic heart failure (CHF) has been known for many centuries, but it has not been investigated extensively until recently. Cardiac cachexia is a common complication of CHF which is associated with poor prognosis, independently of functional disease severity, age, measures of exercise capacity, and left ventricular ejection fraction. Patients with cardiac cachexia suffer from generalised loss of lean tissue, fat tissue, as well as bone tissue. Cachectic CHF patients are weaker and fatigue earlier. This is due to both reduced skeletal muscle mass and impaired skeletal muscle quality. Concerning the pathophysiology of cardiac cachexia, there is increasing evidence that neurohormonal and immune abnormalities may play a crucial role. Cachectic CHF patients have raised plasma levels of norepinephrine, epinephrine, and cortisol, and they show high plasma renin activity and increased plasma aldosterone levels. A number of studies have also shown that cardiac cachexia is linked to raised plasma levels of inflammatory cytokines, such as tumor necrosis factor alpha. The available evidence suggests that cardiac cachexia is a multifactorial neuroendocrine and metabolic disorder with a poor prognosis. A complex imbalance of different body systems, termed catabolic/anabolic imbalance, is likely to be responsible for the development of the wasting process. It is hoped that a better understanding of the pathophysiological mechanisms involved in cardiac cachexia will lead to novel therapeutic strategies in the (near) future.

Effect of interleukin-10 on the production of tumor necrosis factor-alpha by peripheral blood mononuclear cells from patients with chronic heart failure

Chronic heart failure (HF) is a state of inflammatory immune activation characterized by elevated circulating levels of tumor necrosis factor-alpha (TNF-alpha). Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine that inhibits TNF-alpha production and lessens endotoxin bioactivity. It is not known whether IL-10 reduces lipopolysaccharide (LPS) stimulated TNF-alpha production of peripheral blood mononuclear cells (PBMCs) from patients with chronic HF. PBMCs were isolated from 15 patients with chronic HF (New York Heart Association functional class 3.0 +/- 0.2, left ventricular ejection fraction 30 +/- 2%, peak oxygen consumption 18.1 +/- 0.8 ml/kg/min) and 15 healthy control subjects and stimulated with 1 and 10 ng/ml LPS for 24 hours with or without prior addition of IL-10 (10 ng/ml). TNF-alpha was quantified in cell-free supernatants by an enzyme-linked immunosorbent assay. TNF-alpha, soluble TNF receptors, IL-10, and LPS were quantified in plasma. LPS stimulated TNF-alpha production was highest in those patients in New York Heart Association class II (p <0.01 vs New York Heart Association class III and IV, p <0.001 vs control subjects). IL-10 reduced PBMC TNF-alpha production in all stimulated samples at 1 and 10 ng/ml LPS (mean reduction 43% at 1 ng/ml, p <0.01 and 55% at 10 ng/ml, p <0.0001). The percentage reduction in TNF-alpha release did not differ significantly between patients and control subjects or with respect to severity of chronic HF or baseline immune parameters. Independently of clinical severity, IL-10 profoundly inhibits TNF-alpha release from PBMCs isolated from patients with chronic HF. IL-10 is, therefore, a potential therapy for use in chronic HF associated with inflammatory immune activation.

Effect of thalidomide on the skeletal muscle in experimental heart failure

BACKGROUND

Tumour Necrosis Factor alpha (TNFalpha) has been shown to contribute to heart failure (CHF) progression.

AIMS

We have tried to antagonise the detrimental effects of TNFalpha on skeletal muscle apoptosis, by using thalidomide, a drug that inhibits its biosynthesis.

METHODS

CHF was induced in 20 rats by injecting monocrotaline, which determines right ventricle (RV) failure. After 2 weeks, when CHF developed, 12 rats were treated with thalidomide 3.5.mg/kg per day for 2 weeks. Eight had saline and served as CHF controls.

RESULTS

Thalidomide failed to decrease TNFalpha and its second messenger sphingosine (SPH), but was able to prevent the shift toward the fast myosin heavy chains. In the Tibialis Anterior muscle of the thalidomide group, the degree of atrophy, the number of apoptotic nuclei and the levels of caspases, were similar to those of the CHF controls.

CONCLUSIONS

Thalidomide, at the doses used in this study, which are the same employed for the treatment of tubercolosis, leprosy, AIDS and cancer in humans, did not lower either TNFalpha or SPH and only marginally influenced the apoptosis-induced muscle atrophy. Since other TNFalpha blockers are under investigation for improving the clinical status of patients with CHF, the present data could be relevant in the design of randomised clinical trials in humans.