Tumor necrosis factor alpha (TNF alpha) is cardiodepressant in pathophysiologically relevant concentrations without inducing inducible nitric oxide-(NO)-synthase (iNOS) or triggering serious cytotoxicity

Tachycardia and Atrial Fibrillation-Related Cardiomyopathies: Potential Mechanisms and Current Therapies

Atrial fibrillation (AF) is associated with an increased risk of new-onset ventricular contractile dysfunction, termed arrhythmia-induced cardiomyopathy (AIC). Although cardioembolic stroke remains the most feared and widely studied complication of AF, AIC is also a clinically important consequence of AF that portends significant morbidity and mortality to patients with AF. Current treatments are aimed at restoring sinus rhythm through catheter ablation and rate and rhythm control, but these treatments do not target the underlying molecular mechanisms driving the progression from AF to AIC. Here, we describe the clinical features of the various AIC subtypes, discuss the pathophysiologic mechanisms driving the progression from AF to AIC, and review the evidence surrounding current treatment options. In this review, we aim to identify key knowledge gaps that will enable the development of more effective AIC therapies that target cellular and molecular mechanisms.

Inflammation in Heart Failure-Future Perspectives

Chronic heart failure is a terminal point of a vast majority of cardiac or extracardiac causes affecting around 1-2% of the global population and more than 10% of the people above the age of 65. Inflammation is persistently associated with chronic diseases, contributing in many cases to the progression of disease. Even in a low inflammatory state, past studies raised the question of whether inflammation is a constant condition, or if it is, rather, triggered in different amounts, according to the phenotype of heart failure. By evaluating the results of clinical studies which focused on proinflammatory cytokines, this review aims to identify the ones that are independent risk factors for heart failure decompensation or cardiovascular death. This review assessed the current evidence concerning the inflammatory activation cascade, but also future possible targets for inflammatory response modulation, which can further impact the course of heart failure.

Cirrhotic Cardiomyopathy

PURPOSE OF REVIEW

Cirrhotic cardiomyopathy is a syndrome of depressed cardiac function in patients with cirrhosis. We aimed to review the historical background, pathophysiology and pathogenesis, diagnostic definitions, clinical relevance, and management of this syndrome.

RECENT FINDINGS

An inflammatory phenotype underlies the pathogenesis: gut bacterial translocation with endotoxemia stimulates cytokines and cardiodepressant factors, such as nitric oxide and endocannabinoids. Cardiomyocyte plasma membrane biochemical and biophysical changes also play a pathogenic role. These factors lead to impaired beta-adrenergic function. Proposed new echocardiographic criteria for the diagnosis of cirrhotic cardiomyopathy include systolic global longitudinal strain and indices of diastolic dysfunction. Cardiac dysfunction participates in the pathogenesis of hepatorenal syndrome and increased morbidity/mortality of cirrhotic patients to hemorrhage, infection, and surgery, including liver transplantation. There is no specific treatment, although β-adrenergic blockade and supportive management have been proposed, but it needs further study. Cirrhotic cardiomyopathy is a clinically relevant syndrome afflicting patients with established cirrhosis. Optimum management remains unclear, and further study is needed in this area.

Tumor Necrosis Factor-α in Heart Failure: an Updated Review

PURPOSE OF THE REVIEW

Proinflammatory cytokines are consistently elevated in congestive heart failure. In the current review, we provide an overview on the current understanding of how tumor necrosis factor-α (TNFα), a key proinflammatory cytokine, potentiates heart failure by overwhelming the anti-inflammatory responses disrupting the homeostasis.

RECENT FINDINGS

Studies have shown co-relationship between severity of heart failure and levels of the proinflammatory cytokine TNFα and one of its secondary mediators interleukin-6 (IL-6), suggesting their potential as biomarkers. Recent efforts have focused on understanding the mechanisms of how proinflammatory cytokines contribute towards cardiac dysfunction and failure. In addition, how unchecked proinflammatory cytokines and their cross-talk with sympathetic system overrides the anti-inflammatory response underlying failure. The review offers insights on how TNFα and IL-6 contribute to cardiac dysfunction and failure. Furthermore, this provides a forum to begin the discussion on the cross-talk between sympathetic drive and proinflammatory cytokines and its determinant role in deleterious outcomes.

Proinflammatory Cytokines Mediate GPCR Dysfunction

Proinflammatory reaction by the body occurs acutely in response to injury that is considered primarily beneficial. However, sustained proinflammatory cytokines observed with chronic pathologies such as metabolic syndrome, cancer, and arthritis are detrimental and in many cases is a major cardiovascular risk factor. Proinflammatory cytokines such as interleukin-1, interleukin-6, and tumor necrosis factor α (TNFα) have long been implicated in cardiovascular risk and considered to be a major underlying cause for heart failure (HF). The failure of the anti-TNFα therapy for HF indicates our elusive understanding on the dichotomous role of proinflammatory cytokines on acutely beneficial effects versus long-term deleterious effects. Despite these well-described observations, less is known about the mechanistic underpinnings of proinflammatory cytokines especially TNFα in pathogenesis of HF. Increasing evidence suggests the existence of an active cross-talk between the TNFα receptor signaling and G-protein-coupled receptors such as β-adrenergic receptor (βAR). Given that βARs are the key regulators of cardiac function, the review will discuss the current state of understanding on the role of proinflammatory cytokine TNFα in regulating βAR function.

Etanercept protects rat cardiomyocytes against hypertrophy by regulating inflammatory cytokines secretion and cell apoptosis

We aimed to investigate the effect of etanercept, a tumor necrosis factor-α (TNF-α) inhibitor, on rat cardiomyocyte hypertrophy and its underlying mechanism. Primary neonatal rat cardiomyocytes were isolated from Sprague-Dawley rats. The model of rat cardiomyocyte hypertrophy was induced by endothelin, and then treated with different concentrations of etanercept (1, 10, and 50 μM). After treatment, cell counts, viability and cell apoptosis were evaluated. The mRNA levels of myocardial hypertrophy marker genes, including atrial natriuretic factor (ANF), matrix metalloproteinase (MMP)-9 and MMP-13, were detected by qRT-PCR, and the expressions of apoptosis-related proteins (Bcl-2 and Bax) were measured by western blotting. The protein levels of transforming growth factor-β1 (TGF-β1), interleukin (IL)-1β, IL-6, leukemia inhibitory factor (LIF) and cardiotrophin-1 (CT-1) were determined using enzyme linked immunosorbent assay (ELISA) kits. In the present study, TNF-α level in cardiomyocytes with hypertrophy was significantly enhanced (P<0.05). Compared to the model group, cell number and viability were significantly increased and ratio of apoptotic cells was reduced by etanercept (P<0.05, P<0.01, or P<0.001). In addition, etanercept remarkably reduced the mRNA levels of ANF, MMP-9 and MMP-13, inhibited the expression of Bax, and increased the expression of Bcl-2 compared to the model group (P<0.05). ELISA results further showed that etanercept lowered the levels of IL-1β, IL-6, LIF and CT-1 but not TGF-β1 compared to the model group (P<0.05). Etanercept may protect rat cardiomyocytes from hypertrophy by inhibiting inflammatory cytokines secretion and cell apoptosis.

Metallothionein Prevents Age-Associated Cardiomyopathy via Inhibiting NF-κB Pathway Activation and Associated Nitrative Damage to 2-OGD

AIMS

Cardiac-specific metallothionein (MT) overexpression extends lifespan, but the mechanism underlying the effect of MT protection against age-associated cardiovascular diseases (CVD) remains elusive. To elucidate this, male wild-type and two lines of MT-transgenic (MT-TG) mice, MM and MT-1 (cardiac-specific overexpressing MT about 10- and 80-fold, respectively) at three representative ages (2-3, 9-10, and 18-20 months), were utilized. A stable human MT2A overexpressing cardiomyocytes (H9c2MT7) was also introduced.

RESULTS

Histomorphology and echocardiographic analysis revealed that age-associated cardiac hypertrophy, remodeling, and dysfunction were ameliorated in MT-TG mice. Also, aging-accompanied NF-κB activation, characterized by increased nuclear p65 translocation, elevated DNA-binding activity, and upregulation of inflammatory cytokines, was largely attenuated by MT overexpression. Treatment of H9c2 cardiomyocytes with tumor necrosis factor-α (TNF-α), which mimicked an inflammatory environment, significantly increased NF-κB activity, and some age-related phenotypes appeared. The NF-κB activation was further proved to be pivotal for both age-associated and TNF-α-induced nitrative damage to cardiac 2-oxoglutarate dehydrogenase (2-OGD) by virtue of NF-κB p65 gene silencing. MT inhibited NF-κB activation and associated nitrative damage to cardiac 2-OGD in both old MT-TG hearts and TNF-α-treated H9c2MT7 cardiomyocytes; these protective effects were abolished in H9c2MT7 cardiomyocytes by MT-specific gene silencing. Innovation and Conclusion: Together, these findings indicate that the protective effects of MT against age-associated CVD can be attributed mainly to its role in NF-κB inhibition and resultant alleviation of nitrative damage to 2-OGD. Antioxid. Redox Signal. 25, 936-952.

Decreased beating rate variability of spontaneously contracting cardiomyocytes after co-incubation with endotoxin

Decreased heart rate variability (HRV) in critically ill patients indicates a poor prognosis. In heart failure patients, there is an elevated sympathetic tone, reflected by a dominance of sympathetic parameters in HRV, whereas in critically ill patients sympathetic and parasympathetic modulation of heart rate is attenuated despite increased catecholamine blood levels. Thus, autonomic dysfunction in the critically ill cannot be causally related to an impairment at the level of neural transmission, but may be due to a derangement of signal transduction at the effector cell level. On the basis of our working hypothesis that endotoxin may be involved in this blunting of effector cell response to nerval input, we studied the spontaneous beating of cardiomyocytes under the influence of endotoxin. Applying the clinically established indices of HRV to the analysis of beating rate variability (BRV) of neonatal rat cardiomyocytes in serum-free medium, a narrowing of their BRV by endotoxin is demonstrated. We propose that the narrowing of HRV in critically ill patients does not only reflect the altered input from the central or peripheral neurons, but rather a remodeling of the cardiac pacemaker cells by endotoxin and inflammatory mediators.

Cardiorenal Syndrome Type 1: Activation of Dual Apoptotic Pathways

Cardiorenal syndrome type 1 (CRS1) pathophysiology is complex, and immune-mediated damage, including alterations in the immune response with monocyte apoptosis and cytokine release, has been reported as a potential mechanism. In this study, we examined the putative role of renal tubular epithelial cell (RTC) apoptosis as a pathogenic mechanism in CRS1. In particular, we investigated the caspase pathways involved in induced apoptosis. We enrolled 29 patients with acute heart failure (AHF), 11 patients with CRS1, and 15 controls (CTR) without AHF or acute kidney injury (AKI). Patients who had AKI prior to the episode of AHF or who had any other potential causes of AKI were excluded. Plasma from different groups was incubated with RTCs for 24 h. Subsequently, cell apoptosis, DNA fragmentation, and caspase-3, -8, and -9 activities were investigated in RTCs incubated with AHF, CRS1, and CTR plasma. A p value <0.5 was considered statistically significant. A quantitative analysis of apoptosis showed significantly higher apoptosis rates in CRS1 patients compared to AHF patients and CTR (p < 0.01). This increase in apoptosis was strongly confirmed by caspase-3 levels (ρ = 0.73). Caspase-8 and -9 were significantly higher in CRS1 patients compared to AHF patients and CTR (p < 0.01). Furthermore, caspase-3 levels showed a significantly positive correlation with caspase-8 (ρ = 0.57) and -9 (ρ = 0.47; p < 0.001). This study demonstrated the significantly heightened presence of dual apoptotic disequilibrium in CRS1. Our findings indicated that apoptosis may have a central role in the mechanism of CRS1, and it could be a potential therapeutic target in this syndrome.

Heart-kidney crosstalk and role of humoral signaling in critical illness

Organ failure in the heart or kidney can initiate various complex metabolic, cell-mediated and humoral pathways affecting distant organs, contributing to the high therapeutic costs and significantly higher morbidity and mortality. The universal outreach of cells in an injured state has myriad consequences to distant organ cells and their milieu. Heart performance and kidney function are closely interconnected and communication between these organs occurs through a variety of bidirectional pathways. The term cardiorenal syndrome (CRS) is often used to describe this condition and represents an important model for exploring the pathophysiology of cardiac and renal dysfunction. Clinical evidence suggests that tissue injury in both acute kidney injury and heart failure has immune-mediated inflammatory consequences that can initiate remote organ dysfunction. Acute cardiorenal syndrome (CRS type 1) and acute renocardiac syndrome (CRS type 3) are particularly relevant in high-acuity medical units. This review briefly summarizes relevant research and focuses on the role of signaling in heart-kidney crosstalk in the critical care setting.

Soluble tumor necrosis factor receptors and heart failure risk in older adults: Health, Aging, and Body Composition (Health ABC) Study

BACKGROUND

Tumor necrosis factor (TNF) levels are associated with risk for heart failure (HF). The soluble TNF type 1 (sTNF-R1) and type 2 (sTNF-R2) receptors are elevated in patients with manifest HF, but whether they are associated with risk for incident HF is unclear.

METHODS AND RESULTS

Using Cox proportional hazard models, we examined the association between baseline levels of sTNF-R1 and sTNF-R2 with incident HF risk among 1285 participants of the Health, Aging, and Body Composition Study (age, 74.0±2.9 years; 51.4% women; 41.1% black). At baseline, median (interquartile range) of TNF, sTNF-R1, and sTNF-R2 levels was 3.14 (2.42-4.06), 1.46 (1.25-1.76), and 3.43 (2.95-4.02) ng/mL, respectively. During a median follow-up of 11.4 (6.9-11.7) years, 233 (18.1%) participants developed HF. In models controlling for other HF risk factors, TNF (hazard ratio [HR], 1.28; 95% confidence interval [CI], 1.02-1.61 per log2 increase) and sTNF-R1 (HR, 1.68; 95% CI, 1.15-2.46 per log2 increase), but not sTNF-R2 (HR, 1.15; 95% CI, 0.80-1.63 per log2 increase), were associated with a higher risk for HF. These associations were consistent across whites and blacks (TNF, sTNF-R1, sTNF-R2; interaction P=0.531, 0.091, and 0.795, respectively) and in both sexes (TNF, sTNF-R1, sTNF-R2; interaction P=0.491, 0.672, and 0.999, respectively). TNF-R1 was associated with a higher risk for HF with preserved versus reduced ejection fraction (HR, 1.81; 95% CI, 1.03-3.18; P=0.038 for preserved versus HR, 0.90; 95% CI, 0.56-1.44; P=0.667 for reduced ejection fraction; interaction P=0.05).

CONCLUSIONS

In older adults, elevated levels of sTNF-R1 are associated with increased risk for incident HF. However, addition of TNF-R1 to the previously validated Health ABC HF risk model did not demonstrate material improvement in net discrimination or reclassification.

Treatment with bone morphogenetic protein 2 limits infarct size after myocardial infarction in mice

Various strategies have been devised to reduce the clinical consequences of myocardial infarction, including acute medical care, revascularization, stem cell transplantations, and more recently, prevention of cardiomyocyte cell death. Activation of embryonic signaling pathways is a particularly interesting option to complement these strategies and to improve the functional performance and survival rate of cardiomyocytes. Here, we have concentrated on bone morphogenetic protein 2 (BMP-2), which induces ectopic formation of beating cardiomyocytes during development in the mesoderm and protects neonatal cardiomyocytes from ischemia-reperfusion injury. In a mouse model of acute myocardial infarction, an i.v. injection of BMP-2 reduced infarct size in mice when given after left anterior descending artery ligation. Mice treated with BMP-2 are characterized by a reduced rate of apoptotic cardiomyocytes both in the border zone of the infarcts and in the remote myocardium. In vitro, BMP-2 increases the frequency of spontaneously beating neonatal cardiomyocytes and the contractile performance under electrical pacing at 2 Hz, preserves cellular adenosine triphosphate stores, and decreases the rate of apoptosis despite the increased workload. In addition, BMP-2 specifically induced phosphorylation of Smad1/5/8 proteins and protected adult cardiomyocytes from long-lasting hypoxia-induced cellular damage and oxidative stress without activation of the cardiodepressant transforming growth factor-β pathway. Our data suggest that BMP-2 treatment may have considerable therapeutic potential in individuals with acute and chronic myocardial ischemia by improving the contractility of cardiomyocytes and preventing cardiomyocyte cell death.

Polycystic Ovary Syndrome and Chronic Inflammation: Pharmacotherapeutic Implications

Objective:

To examine the relationship between polycystic ovary syndrome (PCOS), cardiovascular risk factors, cardiovascular disease (CVD), and chronic inflammation and analyze data regarding pharmacologic therapies that are recommended to reduce CVD risk in PCOS and the impact of those therapies on chronic inflammation.

Data Sources:

A search of MEDLINE (1950-October 2011) was conducted to identify clinical studies pertaining to the identification and treatment of CVD and chronic low-grade inflammation in PCOS, Search terms included polycystic ovary syndrome, cardiovascular disease, inflammation, metformin, thiazolidinedione, and statin. Bibliographies of these studies and review articles were also examined.

Study Selection and Data Extraction:

English-language clinical studies evaluating the effect of metformin, thiazolidinediones, and statins on inflammatory markers, endothelial function, adhesion molecules, fibrinolysis, cytokines, and adipokines in PCOS were included.

Data Synthesis:

Women with PCOS have an increased prevalence of many cardiovascular risk factors including obesity, android fat distribution, insulin resistance, impaired glucose tolerance, diabetes, dyslipidemia, hypertension, and metabolic syndrome. Markers of chronic low-grade inflammation, which are associated with an increased risk of CVD, are also elevated in PCOS. Clinical guidelines recommend the use of insulin sensitizers and statins to prevent CVD in some patients with PCOS. Current literature indicates that each of these medication classes has beneficial effects on inflammation, as well. Although there are currently no studies to determine whether these treatments decrease CVD in PCOS, it can be hypothesized that drugs impacting chronic inflammation may reduce cardiovascular risk. Some studies show that metformin, thiazolidinediones, and statins have beneficial effects on inflammatory markers in PCOS; however, the data are inconsistent.

Conclusions:

There is insufficient information to recommend any pharmacologic therapies for their antiinflammatory effects in PCOS in the absence of other indications such as diabetes and dyslipidemia.

β-Adrenergic signaling and response to pressure overload in transgenic mice with cardiac-specific overexpression of inducible NO synthase

The role of iNOS induction in the context of cardiac hypertrophy and heart failure is still not fully understood. We have used transgenic mice with cardiac specific overexpression of iNOS (tg-iNOS) to investigate the consequences of high level NO formation on cardiac function in vivo and the response to chronic pressure overload. Conductance manometry was used to analyze cardiac function of wild type (WT) and tg-iNOS mice under basal conditions and β-adrenergic stimulation. To investigate the influence of iNOS on cardiac function in hypertrophied hearts, transversal aortic constriction was performed. Despite a high level of cardiac NO formation tg-iNOS mice showed almost normal LV function under basal conditions. The cardiac response to β-adrenergic stimulation, however, was completely abolished. Acute NOS inhibition led to an instantaneous recovery of the inotropic response to catecholamines in tg-iNOS mice. Chronic pressure overload induced a similar extent of cardiac hypertrophy in WT and tg-iNOS hearts. LV function, however, was more compromised in tg-iNOS hearts as revealed by a decreased contractility and cardiac output.

IN CONCLUSION

a high level of cardiac NO formation does not induce heart failure per se but severely enhances the functional depression in response to pressure overload. This effect could be due to the tonic impairment of the cardiac β-adrenergic response.

Sepsis-induced cardiomyopathy: a review of pathophysiologic mechanisms

Cardiac dysfunction is a well-recognized complication of severe sepsis and septic shock. Cardiac dysfunction in sepsis is characterized by ventricular dilatation, reduction in ejection fraction and reduced contractility. Initially, cardiac dysfunction was considered to occur only during the "hypodynamic" phase of shock. But we now know that it occurs very early in sepsis even during the "hyperdynamic" phase of septic shock. Circulating blood-borne factors were suspected to be involved in the evolution of sepsis induced cardiomyopathy, but it is not until recently that the cellular and molecular events are being targeted by researchers in a quest to understand this enigmatic process. Septic cardiomyopathy has been the subject of investigation for nearly half a century now and yet controversies exist in understanding it's pathophysiology. Here, we discuss our understanding of the pathogenesis of septic cardiomyopathy and the complex roles played by nitric oxide, mitochondrial dysfunction, complements and cytokines.

Inflammatory markers and incident heart failure risk in older adults: the Health ABC (Health, Aging, and Body Composition) study

OBJECTIVES

The purpose of this study was to evaluate the association between inflammation and heart failure (HF) risk in older adults.

BACKGROUND

Inflammation is associated with HF risk factors and also directly affects myocardial function.

METHODS

The association of baseline serum concentrations of interleukin (IL)-6, tumor necrosis factor-alpha, and C-reactive protein (CRP) with incident HF was assessed with Cox models among 2,610 older persons without prevalent HF enrolled in the Health ABC (Health, Aging, and Body Composition) study (age 73.6 +/- 2.9 years; 48.3% men; 59.6% white).

RESULTS

During follow-up (median 9.4 years), HF developed in 311 (11.9%) participants. In models controlling for clinical characteristics, ankle-arm index, and incident coronary heart disease, doubling of IL-6, tumor necrosis factor-alpha, and CRP concentrations was associated with 29% (95% confidence interval: 13% to 47%; p < 0.001), 46% (95% confidence interval: 17% to 84%; p = 0.001), and 9% (95% confidence interval: -1% to 24%; p = 0.087) increase in HF risk, respectively. In models including all 3 markers, IL-6, and tumor necrosis factor-alpha, but not CRP, remained significant. These associations were similar across sex and race and persisted in models accounting for death as a competing event. Post-HF ejection fraction was available in 239 (76.8%) cases; inflammatory markers had stronger association with HF with preserved ejection fraction. Repeat IL-6 and CRP determinations at 1-year follow-up did not provide incremental information. Addition of IL-6 to the clinical Health ABC HF model improved model discrimination (C index from 0.717 to 0.734; p = 0.001) and fit (decreased Bayes information criterion by 17.8; p < 0.001).

CONCLUSIONS

Inflammatory markers are associated with HF risk among older adults and may improve HF risk stratification.

Intra-aortic balloon counterpulsation in patients with acute myocardial infarction complicated by cardiogenic shock: the prospective, randomized IABP SHOCK Trial for attenuation of multiorgan dysfunction syndrome

OBJECTIVE

Patients undergoing percutaneous coronary intervention (PCI) for acute myocardial infarction with cardiogenic shock (CS) are often treated with intra-aortic balloon pump counterpulsation (IABP), even though the evidence to support this is limited. We determined whether IABP as an addition to PCI-centered therapy ameliorates multiorgan dysfunction syndrome (MODS) in patients with acute myocardial infarction complicated by CS.

DESIGN

A prospective, randomized, controlled, open-label clinical trial recruiting patients between March 2003 and June 2004 (ClinicalTrials.gov ID NCT00469248).

SETTING

Tertiary care university hospital.

PATIENTS AND INTERVENTIONS

Forty-five consecutive patients with AMI and CS undergoing PCI were randomized to treatment with or without IABP.

MEASUREMENTS AND MAIN RESULTS

Acute Physiology and Chronic Health Evaluation (APACHE) II scores (primary outcome measure), hemodynamic values, inflammatory markers, and plasma brain natriuretic peptide (BNP) levels (secondary outcomes) were collected over 4 days from randomization. The prospective hypothesis was that adding IABP therapy to "standard care" would improve CS-triggered MODS. The addition of IABP to standard therapy did not result in a significant improvement in MODS (measured by serial APACHE II scoring over 4 days). IABP use had no significant effect on cardiac index or systemic inflammatory activation, although BNP levels were significantly lower in IABP-treated patients. Initial and serial APACHE II scoring correlated with mortality better than cardiac index, systemic inflammatory state, and BNP levels in this group of patients. Nonsurvivors had significantly higher initial APACHE II scores (29.9 +/- 2.88) than survivors (18.1 +/- 1.66, p < .05). Nevertheless, discrepancies among patients within the groups cannot be ruled out and might interfere with our results.

CONCLUSIONS

In this randomized trial addressing addition of IABP in CS patients, mechanical support was associated only with modest effects on reduction of APACHE II score as a marker of severity of disease, improvement of cardiac index, reduction of inflammatory state, or reduction of BNP biomarker status compared with medical therapy alone. However, the limitations of our present trial preclude any definitive conclusion, but request for a larger prospective, randomized, multicentered trial with mortality as primary end point.

Inflammation in chronic heart failure

OBJECTIVE

To summarize findings regarding the association of inflammatory processes with chronic heart failure (HF).

DATA SOURCES

We conducted PubMed/MEDLINE searches (1966-January 2008) of primary literature using the following key words: ACE inhibitors, allopurinol, angiotensin-receptor antagonists, cardiomyopathy, chemokines, cytokines, diuretics, heart failure, inflammation, interleukins, HMG-CoA reductase inhibitors, immunotherapy, medications used in heart failure, thalidomide, tumor necrosis factor, and uric acid.

STUDY SELECTION AND DATA EXTRACTION

All articles that appeared to be relevant were read; of 305 articles examined, 87 were selected for discussion. Articles were selected if they were written in English and focused on any of the key words or appeared to have substantial content addressing inflammation in HF.

DATA SYNTHESIS

Cytokines, uric acid, and other inflammatory mediators are associated with physiologic effects that are also prominent features of HF (eg, reduced contractility and cardiac output, endothelial dysfunction, hypercoagulability, autonomic dysfunction as evidenced by reduced resting heart rate variability, insulin resistance). With the exception of elevated tumor necrosis factor-alpha as a cause of insulin resistance, it is not clear whether elevated inflammatory mediators directly cause HF signs and symptoms or whether they are incidental markers. Awareness of these associations has occurred relatively recently; there have been few clinical studies of efforts to directly modify inflammatory mediators. Most currently accepted drug therapies of HF reduce concentrations of circulating cytokines, but the significance of these findings awaits directed study.

CONCLUSIONS

Loss of myocardial function, autonomic dysfunction, and glucose intolerance are interrelated and linked by underlying chronic low-grade inflammation. Drug therapy with statins, pentoxifylline, and perhaps urate-lowering agents, in addition to current therapies, holds promise for treatment of HF.

Hemodynamic improvement following levosimendan treatment in patients with acute myocardial infarction and cardiogenic shock*

OBJECTIVES

Levosimendan, a novel inodilator, has been shown to improve hemodynamic function in patients with acute exacerbation of congestive heart failure. We wanted to determine the hemodynamic effects of levosimendan following ineffective conventional therapy (with catecholamines) in patients with cardiogenic shock following myocardial infarction.

DESIGN

Observational hemodynamic study.

SETTING

Tertiary care center university hospital.

PATIENTS

Fifty-six patients with cardiogenic shock secondary to myocardial infarction were treated with percutaneous revascularization (intra-aortic balloon pump where appropriate) and commenced on conventional inotropic therapy.

INTERVENTIONS

Patients with persisting cardiogenic shock 24 hrs after revascularization were additionally treated with levosimendan (rapid bolus of 12 microg/kg for 10 mins, then 0.05-0.2 mug/kg/min for 24 hrs) (n = 25).

MEASUREMENTS AND MAIN RESULTS

With conventional catecholamine therapy (norepinephrine and dobutamine), we observed only marginal improvement in mean arterial pressure or cardiac index. In contrast, the addition of levosimendan produced a significant increase in cardiac index (2.1 +/- 0.56 to 3.0 +/- 1.11 L/min/m2, p < .01) and cardiac power index (0.32 +/- 0.08 to 0.44 +/- 0.18 W, p < .01), whereas systemic vascular resistance decreased significantly (1208 +/- 333 to 858 +/- 299 dyne.sec.cm(-5), p < .01). There was no significant change in blood pressure during levosimendan treatment. Hemodynamic improvement was sustained after levosimendan infusion was stopped.

CONCLUSIONS

Levosimendan infusion in cardiogenic shock following acute myocardial infarction improved cardiovascular hemodynamics without leading to hypotension.

Sepsis is associated with an upregulation of functional beta3 adrenoceptors in the myocardium

OBJECTIVE

To analyze the implication of the beta3-adrenoceptor (beta3-AR) pathway in human septic myocardium and a murine model of sepsis, a condition associated with myocardial depression.

METHODS AND RESULTS

beta3-AR and eNOS protein abundance were increased (332+/-66.4% and 218+/-39.3; P<0.05) in hearts from septic patients. The effect of BRL37344, a beta3-AR-preferential agonist, was analyzed by videomicroscopy on the contractility of neonatal mouse ventricular myocytes (NMVM) incubated with conditioned medium from LPS-stimulated cultured macrophages (Mc-LPS+ medium). Stimulation of untreated NMVM with BRL37344 dose-dependently decreased the amplitude of contractile shortening (P<0.05). This response was abolished by L-NAME (NOS inhibitor). Incubation in Mc-LPS+ medium potentiated the depressing effect of BRL37344 (P<0.05) as well as of SR58611A (P<0.05) in wild-type myocytes. Importantly, the contractile depression was abrogated in cardiomyocytes from beta3-AR KO mice.

CONCLUSIONS

beta3-AR are upregulated during sepsis in the human myocardium and by cytokines in murine cardiomyocytes, where they mediate an increased negative inotropic response to beta3 agonists. Activation of the beta3-AR pathway by catecholamines may contribute to the myocardial dysfunction in sepsis.

Potential role of poly(adenosine 5'-diphosphate-ribose) polymerase activation in the pathogenesis of myocardial contractile dysfunction associated with human septic shock

OBJECTIVE

Sepsis is associated with increased production of superoxide and nitric oxide, with consequent peroxynitrite generation. Cardiodepression is induced in the heart during oxidative stress associated with septic shock. Oxidative and nitrosative stress can lead to activation of the nuclear enzyme poly(adenosine 5'-diphosphate [ADP]-ribose) polymerase (PARP), with subsequent loss of myocardial contractile function. The aim of the study was to investigate whether cardiodepression found in septic patients is associated with plasma markers of myocardial necrosis and with myocardial PARP activation.

DESIGN

Prospective and observational study.

SETTING

University hospital intensive care unit for clinical and surgical patients.

PATIENTS

Twenty-five patients older than 18 yrs presenting with severe sepsis or septic shock. Patients with history of chronic heart failure, cancer, coronary artery disease, diabetes, or acquired immune deficiency syndrome were excluded.

INTERVENTIONS

Patients were followed for 28 days, and biochemical and hemodynamic data were collected on days 1, 3, and 6 of sepsis. The groups were survivors and nonsurvivors, defined only after the end of clinical patient evolution. Heart sections from patients who died were analyzed with hematoxylin-eosin and Picro Sirius-Red immunostaining and with electron microscopy.

MEASUREMENTS AND MAIN RESULTS

The study population included 25 individuals, of whom 12 (48%) died during the 6 days of follow-up. The initial data of the inflammation marker C-reactive protein and Acute Physiologic and Chronic Health. Evaluation severity were similar in both groups (nonsurvivors, 26 +/- 2; survivors, 24 +/- 5; NS). Overall, an increase in plasma troponin level was related to increased mortality risk. In patients who died, significant myocardial damage was detected, and histologic analysis of heart sections showed inflammatory infiltration, increased collagen deposition, and derangement of mitochondrial cristae. Immunohistochemical staining for poly(ADP-ribose) (PAR), the product of activated PARP, was demonstrated in septic hearts. There was a positive correlation between PAR staining densitometry and troponin I (r(2) = 0.73; p < .05), and the correlation of PAR staining densitometry and left ventricular systolic stroke work index was r(2) = 0.33 (p = .0509).

CONCLUSION

There is significant PARP activation in the hearts of septic patients with impaired cardiac function. We hypothesize that PARP activation may be partly responsible for the cardiac depression seen in humans with severe sepsis.

Is there a role for cardiomyocyte toll-like receptor 4 in endotoxemia?

Lipopolysaccharide (LPS) is thought to be an important molecule in myocardial depression in sepsis. Toll-like receptor 4 (TLR4), the lipopolysaccharide receptor, is known to underlie these responses. Because TLR4 is expressed on both cardiac myocytes and immune cells, it is unclear as to which cell type is responsible for myocyte depression. In this article, we present evidence that the early response is likely related to TLR4 on immune cells and most likely macrophages, whereas the more delayed response may involve various immune cells as well as myocytes.

Cytokines and cardiovascular disease

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

Cytokine-Induced Modulation of Cardiac Function

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

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

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

[Cardiogenic shock: pathophysiology, clinics, therapeutical options and perspectives]

Documented mortality from myocardial infarction (MI) has significantly decreased from around 30% in the 1960s to 6-7% currently, following the introduction of intensive care treatment, thrombolysis, effective antithrombotic therapy and coronary angioplasty. However, the approximate mortality of 70-80% of patients with cardiogenic shock following acute MI has hardly improved despite the introduction of modern treatment strategies. The major cause of in-hospital MI mortality remains myocardial failure with consecutive cardiogenic shock and multi-organ failure. Prompt coronary revascularisation by "facilitated" or "adjunctive" percutaneous coronary intervention (PCI), is currently considered the best method to reduce the high mortality in these patients. Facilitated PCI includes administration of glycoproteine receptor antagonists, mechanical circulation support strategies, such as, intraaortic balloon counterpulsation and potentially prehospital thrombolysis.

Endotoxin-induced myocardial dysfunction: evidence for a role of sphingosine production

OBJECTIVE

To determine whether sphingomyelinase pathway activation would participate in myocardial depression induced by endotoxin.

DESIGN

Randomized, controlled trial.

SETTING

Experimental laboratory.

SUBJECTS

Male Sprague-Dawley rats, isolated rat heart, and cardiac myocytes.

INTERVENTIONS

Cardiovascular function was evaluated in rats injected with saline, endotoxin (10 mg/kg, intravenously), and N-oleoylethanolamine (NOE; 10 mg/kg, intravenously). In ex vivo experiments, isolated rat hearts were perfused with endotoxin (5 microg/mL). For pharmacologic intervention, NOE (1 micromol/L) was admixed to the perfusate 20 mins before endotoxin. In in vitro experiments, ventricular myocytes were incubated with sphingosine (20 microM). Myocyte cell shortening and calcium transient were measured. Mitochondrial membrane potential was measured using the cationic dye tetramethylrhodamine methylester fluorescence technique.

MEASUREMENTS AND MAIN RESULTS

Endotoxin treatment at 4 hrs did not alter mean arterial pressure and abdominal blood flow compared with control rats. Left ventricle developed pressure (LVDP) and its first derivatives (i.e., maximal and minimal change in pressure over time [dP/dtmax and dP/dtmin]) were decreased after 4 hrs in endotoxin-treated rats compared with control rats. NOE (10 mg/kg) treatment largely prevented left ventricular systolic function alterations of endotoxin-treated hearts (n = 6 in each group). In isolated rat heart, endotoxin (5 microg/mL) caused increases in tumor necrosis factor-alpha perfusate concentration and delayed depression of LVDP, dP/dtmax, and dP/dtmin after 60 mins, which was partially abrogated in the presence of the ceramidase inhibitor NOE (1 micromol/L). Sphingosine (20 microM) caused decreases in cell fractional shortening, calcium transient, and mitochondrial membrane potential of cardiac myocytes.

CONCLUSION

These observations suggest that the sphingomyelinase pathway participates in endotoxin-induced myocardial depression.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Myocardial dysfunction with coronary microembolization: signal transduction through a sequence of nitric oxide, tumor necrosis factor-alpha, and sphingosine

Coronary microembolization results in progressive myocardial dysfunction, with causal involvement of tumor necrosis factor-alpha (TNF-alpha). TNF-alpha uses a signal transduction involving nitric oxide (NO) and/or sphingosine. Therefore, we induced coronary microembolization in anesthetized dogs and studied the role and sequence of NO, TNF-alpha, and sphingosine for the evolving contractile dysfunction. Four sham-operated dogs served as controls (group 1). Eleven dogs received placebo (group 2), 6 dogs received the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME, group 3), and 6 dogs received the ceramidase inhibitor N-oleoylethanolamine (NOE, group 4) before microembolization was induced by infusion of 3000 microspheres (42-microm diameter) per milliliter inflow into the left circumflex coronary artery. Posterior systolic wall thickening (PWT) remained unchanged in group 1 but decreased progressively in group 2 from 20.6+/-4.9% (mean+/-SD) at baseline to 4.1+/-3.7% at 8 hours after microembolization. Leukocyte count, TNF-alpha, and sphingosine contents were increased in the microembolized posterior myocardium. In group 3, PWT remained unchanged (20.3+/-2.6% at baseline) with intracoronary administration of L-NAME (20.8+/-3.4%) and 17.7+/-2.3% at 8 hours after microembolization; TNF-alpha and sphingosine contents were not increased. In group 4, PWT also remained unchanged (20.7+/-4.6% at baseline) with intravenous administration of NOE (19.5+/-5.7%) and 16.4+/-6.3% at 8 hours after microembolization; TNF-alpha, but not sphingosine content, was increased. In all groups, systemic hemodynamics, anterior systolic wall thickening, and regional myocardial blood flow remained unchanged throughout the protocols. A signal transduction cascade of NO, TNF-alpha, and sphingosine is causally involved in the coronary microembolization-induced progressive contractile dysfunction.

Cardiac-specific overexpression of inducible nitric oxide synthase does not result in severe cardiac dysfunction

Nitric oxide (NO), a potent regulator of myocardial contractility, has been implicated in the development of heart failure; however, no study exists describing the relation between expression of inducible nitric oxide synthase (iNOS), formation of NO in vivo, and cardiac contractility. We have therefore generated transgenic (TG) mice overexpressing iNOS under the cardiospecific alpha-myosin heavy chain (alpha-MHC) promoter. In vitro, iNOS activity in hearts of two transgenic lines was 260- to 400-fold above controls (wild type [WT]), but TG mice were viable and appeared normal. Ventricular mass/body weight ratio did not differ; heart rate and cardiac output as well as mean arterial blood pressure were decreased by 10%. NO(x) levels of hearts and blood of TG mice were 2.5- and 2-fold above WT controls, respectively. In the isolated heart, release of the NO oxidation products nitrate and nitrite, an index of in vivo NOS activity, was 40-fold over WT. However, cardiac hemodynamics and levels of ATP and phosphocreatine were unaltered. The high iNOS activity was associated with reduced cardiac L-arginine in TG hearts to only 15% of the WT, indicating limited substrate availability, whereas L-citrulline was 20-fold elevated. Our findings demonstrate that the heart can tolerate high levels of iNOS activity without detrimental functional consequences. The concept that iNOS-derived NO is the triggering factor in the pathomechanism leading to heart failure therefore needs to be reevaluated.

Plasma monocyte chemoattractant protein-1 and pulmonary vascular resistance in chronic thromboembolic pulmonary hypertension

The pathogenesis of severe pulmonary hypertension seems to be related to inflammatory response in diseased sites. Monocyte chemoattractant protein-1 (MCP-1) has been reported to play a role in the development of congestive heart failure. In this immunological response, activation and migration of leukocytes including macrophages to the inflammatory region are important factors. We hypothesized that the severity of pulmonary hypertension may be related to MCP-1, which is thought to be upregulated by blood pressure or shear stress in pulmonary vasculature as well as by immunological and inflammatory reactions in chronic thromboembolic pulmonary hypertension (CTEPH). Circulating levels of MCP-1, interleukin-1beta (IL-1beta), and tumor necrosis factor-alpha (TNF-alpha) were measured by sandwich ELISA in 14 patients with CTEPH. The plasma level of MCP-1 was significantly correlated with pulmonary vascular resistance. In IL-1beta and TNF-alpha, on the other hand, there was no correlation between cytokines and pulmonary hemodynamics. Pathological specimens obtained from the patients with CTEPH undergoing thromboendarterectomy demonstrated immunoreactivity of MCP-1 in endothelium, smooth muscle cells, and macrophages within neointima in the hypertensive large elastic pulmonary artery. We conclude that MCP-1 is upregulated in the remodeling of pulmonary arteries in close association with increased pulmonary vascular resistance in CTEPH.

Alterations in cardiac function and gene expression during autoimmune myocarditis in mice

Although myocarditis has been implicated in the pathogenesis of heart failure, a definitive relationship between myocardial inflammation, cardiac dysfunction, and changes in myocyte gene expression has not been established. In this study, we examined the hypothesis that myocardial inflammation and replacement fibrosis following an autoimmune response can progress to cardiac dysfunction and may result in progression to the heart failure phenotype. SWXJ mice were immunized with cardiac myosin on day 0 and day 7, in order to induce an autoimmune response to the myosin protein. Cardiac catheterization via the right carotid artery was performed on days 14, 21, 28, 35, and 42, using a 1.4F Millar transducer-tipped catheter. Hearts were weighed, and cross-sections were cut and stained with either haematoxylin and eosin or Masson's trichrome, in order to identify areas of inflammation and/or fibrosis. Myocardial gene expression was determined by Northern blot analysis. In mice with histological evidence of myocarditis, the heart weight/body weight ratio increased beginning on day 14, and cardiac function decreased beginning on day 21. Myocardial inflammation was accompanied by significant fibrosis beginning on day 21. Quantitation of mRNA showed expression of ventricular atrial naturietic factor, as well as a decrease in myosin heavy chain alpha, beginning on day 21. These data demonstrate that autoimmune inflammation of the heart results in significant cardiac dysfunction, leading to phenotypic alterations similar to those demonstrated in human heart failure and animal models of heart failure.

Enhancement of neonatal innate defense: effects of adding an N-terminal recombinant fragment of bactericidal/permeability-increasing protein on growth and tumor necrosis factor-inducing activity of gram-negative bacteria tested in neonatal cord blood ex vivo

Innate defense against microbial infection requires the action of neutrophils, which have cytoplasmic granules replete with antibiotic proteins and peptides. Bactericidal/permeability-increasing protein (BPI) is found in the primary granules of adult neutrophils, has a high affinity for lipopolysaccharides (or "endotoxins"), and exerts selective cytotoxic, antiendotoxic, and opsonic activity against gram-negative bacteria. We have previously reported that neutrophils derived from newborn cord blood are deficient in BPI (O. Levy et al., Pediatrics 104:1327-1333, 1999). The relative deficiency in BPI of newborns raised the possibility that supplementing the levels of BPI in plasma might enhance newborn antibacterial defense. Here we determined the effects of addition of recombinant 21-kDa N-terminal BPI fragment (rBPI(21)) on the growth and tumor necrosis factor (TNF)-inducing activity of representative gram-negative clinical isolates. Bacteria were tested in citrated newborn cord blood or adult peripheral blood. Bacterial viability was assessed by plating assay, and TNF-alpha release was measured by enzyme-linked immunosorbent assay. Whereas adult blood limited the growth of all isolates except Klebsiella pneumoniae, cord blood also allowed logarithmic growth of Escherichia coli K1/r and Citrobacter koseri. Bacteria varied in their susceptibility to rBPI(21)'s bactericidal action: E. coli K1/r was relatively susceptible (50% inhibitory concentration [IC(50)], approximately 10 nM), C. koseri was intermediate (IC(50), approximately 1,000 nM), Klebsiella pneumoniae was resistant (IC(50), approximately 10,000 nM), and Enterobacter cloacae and Serratia marcescens were highly resistant (IC(50), >10,000 nM). All isolates were potent inducers of TNF-alpha activity in both adult and newborn cord blood. In contrast to its variable antibacterial activity, rBPI(21) consistently inhibited the TNF-inducing activity of all strains tested (IC(50), 1 to 1,000 nM). The antibacterial effects of rBPI(21) were additive with those of a combination of conventional antibiotics typically used to treat bacteremic newborns (ampicillin and gentamicin). Whereas ampicillin and gentamicin demonstrated little inhibition of bacterially induced TNF release, addition of rBPI(21) either alone or together with ampicillin and gentamicin profoundly inhibited release of this cytokine. Thus, supplementing newborn cord blood with rBPI(21) potently inhibited the TNF-inducing activity of a variety of gram-negative bacterial clinical pathogens and, in some cases, enhanced bactericidal activity. These results suggest that administration of rBPI(21) may be of clinical benefit to neonates suffering from gram-negative bacterial infection and/or endotoxemia.

Inotropic response to endothelin-1, isoprenaline and calcium in cardiomyocytes isolated from endotoxin treated rats: effects of ethyl-isothiourea and dexamethasone

1. The contractile effects of endothelin-1, isoprenaline and extracellular calcium were assessed on ventricular cardiomyocytes isolated from lipopolysaccharide-treated rats. The involvement of nitric oxide was investigated using dexamethasone (in vivo) and ethyl isothiourea (in vitro). 2. Male Wistar rats (n=70) were injected with either saline (1 ml kg(-1)) or lipopolysaccharide (LPS; 5 mg kg(-1)) alone, or following pre-treatment with dexamethasone (DEX+LPS; 5 mg kg(-1)). Ventricular cell shortening was recorded using a video edge detection system, and concentration-response relationships were established for endothelin-1, isoprenaline and calcium, in the absence or presence of ethyl isothiourea (ETU; 10 microM). iNOS expression was assessed using reverse transcription-polymerase chain reaction. 3. iNOS mRNA expression was greater (P<0.001) in the LPS (iNOS/GAPDH ratio: 0.90+/-0.09) treated group compared to saline (iNOS/GAPDH ratio: 0.36+/-0.02). Baseline contractile amplitude was reduced (P<0.05) in the LPS (7.3+/-0.2 microm) and DEX+LPS groups (6.7+/-0.3 microm) compared to saline (8. 0+/-0.2 microm). 4. The concentration-dependent contractile response to endothelin-1 was attenuated (P<0.05) in the LPS group compared to saline (maximum change: 0.45+/-0.2 vs 1.8+/-0.2 microm). Neither ETU nor dexamethasone improved contractile function in the LPS-treated animals. 5. The concentration-dependent increase in the contractile response to isoprenaline was attenuated in the LPS-treated group compared to saline (P<0.05; maximum change: 1.7+/-0.4 vs 3.1+/-0.4 microm). This effect was reversed by ETU (maximum change: 3.7+/-0.6 microm). Pre-treatment with dexamethasone prevented a significant fall in contraction amplitude (maximum change: 2.4+/-0.4 microm). 6. The contractile response to calcium was reduced (P<0.05) in the LPS group compared to saline (maximum change: 8.7+/-0.6 vs 10.7+/-0.8 microm). Neither ETU nor dexamethasone restored contractile function in the LPS-treated group. 7. In conclusion, a nitric oxide-mediated inhibitory pathway is not responsible for the diminished contractile response to either endothelin-1 or extracellular calcium, but contributes to the hyporesponsiveness to isoprenaline in lipopolysaccharide treated rats.