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

Interleukin-10 and Transforming Growth Factor Beta1 Gene Polymorphisms in Chronic Heart Failure

BACKGROUND

As cytokines, including interleukin-10 (IL-10) and transforming growth factor beta 1(TGF-β1) seem to contribute towards the pathogenesis of chronic heart failure (CHF), this study was performed to assess the associations of certain single nucleotide polymorphisms (SNPs) of these genes in a case control study.

METHODS

This investigation was carried out to determine the frequency of alleles, genotypes and haplotypes of TGF-β1 and IL-10 single-nucleotide polymorphisms (SNPs) in 57 Iranian patients with CHF compared with 140 healthy subjects using polymerase chain reaction with sequence-specific primers method.

RESULTS

Results of the analyzed data divulged a negative association for both TGF-β1 GC genotype at codon 25 (P=0.047) and CT genotype at codon 10 (P=0.018) and CHF proneness. Although, TGF-β1 CC genotype at codon 10 was found to be positively associated with CHF (P=0.011). Moreover, the frequency of IL-10 (-1082, -819, -592) ATA haplotype and TGF-β1 (codon 10, codon 25) TG haplotype were significantly lower in the patients group (P=0.004 and P=0.040, respectively), while TGF-β1 (codon 10, codon 25) CG haplotype was overrepresented in patients with CHF (P=0.007).

CONCLUSIONS

Cytokine gene polymorphisms might affect vulnerability to CHF. Particular genotypes and haplotypes in IL-10 and TGF-β1 genes could render individuals more susceptible to CHF.

CaMKIIδ interacts directly with IKKβ and modulates NF-κB signalling in adult cardiac fibroblasts

Calcium/calmodulin dependent protein kinase IIδ (CaMKIIδ) acts as a molecular switch regulating cardiovascular Ca²⁺ handling and contractility in health and disease. Activation of CaMKIIδ is also known to regulate cardiovascular inflammation and is reported to be required for pro-inflammatory NF-κB signalling. In this study the aim was to characterise how CaMKIIδ interacts with and modulates NF-κB signalling and whether this interaction exists in non-contractile cells of the heart. Recombinant or purified CaMKIIδ and the individual inhibitory -κB kinase (IKK) proteins of the NF-κB signalling pathway were used in autoradiography and Surface Plasmon Resonance (SPR) to explore potential interactions between both components. Primary adult rat cardiac fibroblasts were then used to study the effects of selective CaMKII inhibition on pharmacologically-induced NF-κB activation as well as interaction between CaMKII and specific IKK isoforms in a cardiac cellular setting. Autoradiography analysis suggested that CaMKIIδ phosphorylated IKKβ but not IKKα. SPR analysis further supported a direct interaction between CaMKIIδ and IKKβ but not between CaMKIIδ and IKKα or IKKγ. CaMKIIδ regulation of IκΒα degradation was explored in adult cardiac fibroblasts exposed to pharmacological stimulation. Cells were stimulated with agonist in the presence or absence of a CaMKII inhibitor, autocamtide inhibitory peptide (AIP). Selective inhibition of CaMKII resulted in reduced NF-κB activation, as measured by agonist-stimulated IκBα degradation. Importantly, and in agreement with the recombinant protein work, an interaction between CaMKII and IKKβ was evident following Proximity Ligation Assays in adult cardiac fibroblasts. This study provides new evidence supporting direct interaction between CaMKIIδ and IKKβ in pro-inflammatory signalling in cardiac fibroblasts and could represent a feature that may be exploited for therapeutic benefit.

Effects of eicosapentaenoic acid on the levels of inflammatory markers, cardiac function and long-term prognosis in chronic heart failure patients with dyslipidemia

AIMS

The effects of eicosapentaenoic acid (EPA) on the levels of inflammatory markers, cardiac function and long-term prognosis in chronic heart failure (CHF) patients with dyslipidemia remain unclear.

METHODS

A total of 139 CHF patients with a mean left ventricular ejection fraction (LVEF) of 37.6± 8.0% were divided into two groups based on whether EPA was included in their treatment regimen: the EPA group (n=71) and the no EPA group (n=68). Only patients with dyslipidemia at baseline (entry) were treated with EPA. The monocyte chemoattractant protein (MCP)-1 and asymmetric dimethylarginine (ADMA) levels were measured at baseline and after 12 months of treatment.

RESULTS

At 12 months, in the EPA group, the LVEF had improved and the MCP-1 and ADMA levels had decreased (respectively, p＜0.001); however, in the no EPA group, the LVEF had worsened, while the MCP-1 and ADMA levels had increased (respectively, p＜0.001). Fifty-five patients experienced cardiac events, including 15 cardiac deaths and 40 readmissions for worsening of CHF during a median follow-up period of 28.0 months. The percent change in LVEF from baseline was found to be significantly associated with the percent change in ADMA (r=-0.462, p＜0.001). A multivariate Cox hazard analysis showed EPA treatment (hazard ratio: 0.21, 95% confidence interval: 0.05-0.93, p=0.031) to be an independent predictor of cardiac events.

CONCLUSIONS

These data indicate that EPA treatment may improve the cardiac function and long-term prognosis of CHF patients with dyslipidemia, at least in part, due to reductions in inflammation and improvements in the endothelial function.

Successful use of mRNA-nucleofection for overexpression of interleukin-10 in murine monocytes/macrophages for anti-inflammatory therapy in a murine model of autoimmune myocarditis

Background

Overexpression of interleukin-10 (IL-10) in murine CD11b⁺ monocytes/macrophages via GMP-adapted mRNA-nucleofection was expected to improve clinical outcome and reduce adverse side effects in autoimmune myocarditis. This study represents the proof of principle for a novel anti-inflammatory therapy using overexpression of IL-10 in murine monocytes/macrophages by mRNA-nucleofection for the treatment of autoimmune myocarditis.

Methods and Results

Autoimmune myocarditis was induced in A/J mice by subcutaneous immunization with troponin I. CD11b⁺ monocytes/macrophages were isolated from the peritoneum and IL-10 was overexpressed by mRNA-nucleofection. These cells were injected intravenously. Myocardial inflammation was assessed via histological and immunohistochemical examinations. Myocardial fibrosis was analyzed with Masson's trichrome staining. Antitroponin I antibodies were determined within the serum. Physical performance was evaluated using a running wheel and echocardiography. In vitro overexpression of IL-10 in CD11b⁺ monocytes/macrophages resulted in a 7-fold increased production of IL-10 (n=3). In vivo higher levels of IL-10 and less inflammation were detected within the myocardium of treated compared with control mice (n=4). IL-10–treated mice showed lower antitroponin I antibodies (n=10) and a better physical performance (n=10).

Conclusions

Application of IL-10–overexpressing CD11b⁺ monocytes/macrophages reduced inflammation and improved physical performance in a murine model of autoimmune myocarditis. Thus, the use of genetically modified monocytes/macrophages facilitated a targeted therapy of local inflammation and may reduce systemic side effects. Because the nucleofection technique is GMP adapted, an in vivo use in humans seems basically feasible and the transfer to other inflammatory diseases seems likely.

Dietary fat and heart failure: moving from lipotoxicity to lipoprotection

There is growing evidence suggesting that dietary fat intake affects the development and progression of heart failure. Studies in rodents show that in the absence of obesity, replacing refined carbohydrate with fat can attenuate or prevent ventricular expansion and contractile dysfunction in response to hypertension, infarction, or genetic cardiomyopathy. Relatively low intake of n-3 polyunsaturated fatty acids from marine sources alters cardiac membrane phospholipid fatty acid composition, decreases the onset of new heart failure, and slows the progression of established heart failure. This effect is associated with decreased inflammation and improved resistance to mitochondrial permeability transition. High intake of saturated, monounsaturated, or n-6 polyunsaturated fatty acids has also shown beneficial effects in rodent studies. The underlying mechanisms are complex, and a more thorough understanding is needed of the effects on cardiac phospholipids, lipid metabolites, and metabolic flux in the normal and failing heart. In summary, manipulation of dietary fat intake shows promise in the prevention and treatment of heart failure. Clinical studies generally support high intake of n-3 polyunsaturated fatty acids from marine sources to prevent and treat heart failure. Additional clinical and animals studies are needed to determine the optimal diet in terms of saturated, monounsaturated, and n-6 polyunsaturated fatty acids intake for this vulnerable patient population.

Effects of supplementation with polyunsaturated fatty acids in patients with heart failure

Despite the clinical and prognostic improvement obtained with the current medical treatment, heart failure (HF) continues to have high morbidity and mortality and its prevalence is increasing in most regions of the world. Thus, there is a need for novel adjunctive therapies that act independently of current neurohormonally and haemodynamically oriented drugs. Nutritional approaches are particularly attractive because they could work additively with established therapies without negative hemodynamic effects. There is growing evidence that omega-3 polyunsaturated fatty acids (n-3 PUFAs) supplementation positively impacts established pathophysiological mechanisms in HF and thus has a potential role for preventing and treating HF. The results of the GISSI-HF trial have indicated that, in patients with chronic HF on evidence-based therapy, long term treatment with PUFAs reduced mortality and hospitalizations for cardiovascular reasons, irrespective of etiology and left ventricular (LV) ejection fraction (EF). The purpose of this review is to summarize the evidence emerged from studies conducted so far on the effect of n-3 PUFAs in HF.

Lack of chemokine signaling through CXCR5 causes increased mortality, ventricular dilatation and deranged matrix during cardiac pressure overload

RATIONALE

Inflammatory mechanisms have been suggested to play a role in the development of heart failure (HF), but a role for chemokines is largely unknown. Based on their role in inflammation and matrix remodeling in other tissues, we hypothesized that CXCL13 and CXCR5 could be involved in cardiac remodeling during HF.

OBJECTIVE

We sought to analyze the role of the chemokine CXCL13 and its receptor CXCR5 in cardiac pathophysiology leading to HF.

METHODS AND RESULTS

Mice harboring a systemic knockout of the CXCR5 (CXCR5(-/-)) displayed increased mortality during a follow-up of 80 days after aortic banding (AB). Following three weeks of AB, CXCR5(-/-) developed significant left ventricular (LV) dilatation compared to wild type (WT) mice. Microarray analysis revealed altered expression of several small leucine-rich proteoglycans (SLRPs) that bind to collagen and modulate fibril assembly. Protein levels of fibromodulin, decorin and lumican (all SLRPs) were significantly reduced in AB CXCR5(-/-) compared to AB WT mice. Electron microscopy revealed loosely packed extracellular matrix with individual collagen fibers and small networks of proteoglycans in AB CXCR5(-/-) mice. Addition of CXCL13 to cultured cardiac fibroblasts enhanced the expression of SLRPs. In patients with HF, we observed increased myocardial levels of CXCR5 and SLRPs, which was reversed following LV assist device treatment.

CONCLUSIONS

Lack of CXCR5 leads to LV dilatation and increased mortality during pressure overload, possibly via lack of an increase in SLRPs. This study demonstrates a critical role of the chemokine CXCL13 and CXCR5 in survival and maintaining of cardiac structure upon pressure overload, by regulating proteoglycans essential for correct collagen assembly.

The beneficial effect of n-3 polyunsaturated fatty acids on doxorubicin-induced chronic heart failure in rats

This study was designed to assess the effects of dietary supplementation with n-3 polyunsaturated fatty acids (PUFA) from fish oil on the response of doxorubicin-induced chronic heart failure in rats. Male Sprague-Dawley rats were treated daily for 8 weeks with normal saline or n-3 PUFA intragastrically after induction of myocardial injury by intraperitoneal injection of doxorubicin 2 mg/kg once weekly for 8 weeks. Cardiac function was assessed by echocardiography. The cytoprotective role of n-3 PUFA against doxorubicin-induced myocardial injury was demonstrated by light microscopy, and serum cytokines (tumour necrosis factor-alpha and interleukin-10) were analysed by enzyme-linked immunosorbent assay. Doxorubicin induced death, alterations in echocardiography parameters and histological damage, all of which are features that characterize heart failure. There were significant differences between the doxorubicin-induced heart failure group and the n-3 PUFA-treated group in terms of echocardiography parameters and cytokine changes. Thus, dietary supplementation with n-3 PUFA attenuated doxorubicin-induced cardiac dysfunction, an effect that might be associated with recovery from an imbalance of the cytokine network.

omega-3 polyunsaturated fatty acid supplementation for the treatment of heart failure: mechanisms and clinical potential

Heart failure (HF) is a complex clinical syndrome with multiple aetiologies. Current treatment options can slow the progression to HF, but overall the prognosis remains poor. Clinical studies suggest that high dietary intake of the omega-3 polyunsaturated fatty acids (omega-3PUFA) found in fish oils (eicosapentaenoic and docosahexaenoic acids) may lower the incidence of HF, and that supplementation with pharmacological doses prolongs event-free survival in patients with established HF. The mechanisms for these potential benefits are complex and not well defined. It is well established that fish oil supplementation lowers plasma triglyceride levels, and more recent work demonstrates anti-inflammatory effects, including reduced circulating levels of inflammatory cytokines and arachidonic acid-derived eicosanoids, and elevated plasma adiponectin. In animal studies, fish oil favourably alters cardiac mitochondrial function. All of these effects may work to prevent the development and progression of HF. The omega-3PUFA found in plant sources, alpha-linolenic acid, may also be protective in HF; however, the evidence is not as compelling as for fish oil. This review summarizes the evidence related to use of omega-3PUFA supplementation as a potential treatment for HF and discusses possible mechanisms of action. In general, there is growing evidence that supplementation with omega-3PUFA positively impacts established pathophysiological targets in HF and has potential therapeutic utility for HF patients.

Astaxanthin: a novel potential treatment for oxidative stress and inflammation in cardiovascular disease

Oxidative stress and inflammation are implicated in several different manifestations of cardiovascular disease (CVD). They are generated, in part, from the overproduction of reactive oxygen species (ROS) and reactive nitrogen species (RNS) that activate transcriptional messengers, such as nuclear factor-kappaB, tangibly contributing to endothelial dysfunction, the initiation and progression of atherosclerosis, irreversible damage after ischemic reperfusion, and even arrhythmia, such as atrial fibrillation. Despite this connection between oxidative stress and CVD, there are currently no recognized therapeutic interventions to address this important unmet need. Antioxidants that provide a broad, "upstream" approach via ROS/RNS quenching or free radical chain breaking seem an appropriate therapeutic option based on epidemiologic, dietary, and in vivo animal model data. However, human clinical trials with several different well-known agents, such as vitamin E and beta-carotene, have been disappointing. Does this mean antioxidants as a class are ineffective, or rather that the "right" compound(s) have yet to be found, their mechanisms of action understood, and their appropriate targeting and dosages determined? A large class of potent naturally-occurring antioxidants exploited by nature-the oxygenated carotenoids (xanthophylls)-have demonstrated utility in their natural form but have eluded development as successful targeted therapeutic agents up to the present time. This article characterizes the mechanism by which this novel group of antioxidants function and reviews their preclinical development. Results from multiple species support the antioxidant/anti-inflammatory properties of the prototype compound, astaxanthin, establishing it as an appropriate candidate for development as a therapeutic agent for cardiovascular oxidative stress and inflammation.

Prevention and reversal of cardiac hypertrophy by soluble epoxide hydrolase inhibitors

Sustained cardiac hypertrophy represents one of the most common causes leading to cardiac failure. There is emerging evidence to implicate the involvement of NF-kappaB in the development of cardiac hypertrophy. However, several critical questions remain unanswered. We tested the use of soluble epoxide hydrolase (sEH) inhibitors as a means to enhance the biological activities of epoxyeicosatrienoic acids (EETs) to treat cardiac hypertrophy. sEH catalyzes the conversion of EETs to form the corresponding dihydroxyeicosatrienoic acids. Previous data have suggested that EETs may inhibit the activation of NF-kappaB-mediated gene transcription. We directly demonstrate the beneficial effects of several potent sEH inhibitors (sEHIs) in cardiac hypertrophy. Specifically, we show that sEHIs can prevent the development of cardiac hypertrophy using a murine model of pressure-induced cardiac hypertrophy. In addition, sEHIs reverse the preestablished cardiac hypertrophy caused by chronic pressure overload. We further demonstrate that these compounds potently block the NF-kappaB activation in cardiac myocytes. Moreover, by using in vivo electrophysiologic recordings, our study shows a beneficial effect of the compounds in the prevention of cardiac arrhythmias that occur in association with cardiac hypertrophy. We conclude that the use of sEHIs to increase the level of the endogenous lipid epoxides such as EETs may represent a viable and completely unexplored avenue to reduce cardiac hypertrophy by blocking NF-kappaB activation.

Caspase inhibition protects against reovirus-induced myocardial injury in vitro and in vivo

Viral myocarditis is a disease with a high morbidity and mortality. The pathogenesis of this disease remains poorly characterized, with components of both direct virus-mediated and secondary inflammatory and immune responses contributing to disease. Apoptosis has increasingly been viewed as an important mechanism of myocardial injury in noninfectious models of cardiac disease, including ischemia and failure. Using a reovirus murine model of viral myocarditis, we characterized and targeted apoptosis as a key mechanism of virus-associated myocardial injury in vitro and in vivo. We demonstrated caspase-3 activation, in conjunction with terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling and annexin binding, in cardiac myocytes after myocarditic viral infection in vitro. We also demonstrated a tight temporal and geographical correlation between caspase-3 activation, histologic injury, and viral load in cardiac tissue after myocarditic viral infection in vivo. Two pharmacologic agents that broadly inhibit caspase activity, Q-VD-OPH and Z-VAD(OMe)-FMK, effectively inhibited virus-induced cellular death in vitro. The inhibition of caspase activity in vivo by the use of pharmacologic agents as well as genetic manipulation reduced virus-induced myocardial injury by 40 to 60% and dramatically improved survival in infected caspase-3-deficient animals. This study indicates that apoptosis plays a critical role in mediating cardiac injury in the setting of viral myocarditis and is the first demonstration that caspase inhibition may serve as a novel therapeutic strategy for this devastating disease.

Therapeutic left ventricular assist device and apheresis on dilated cardiomyopathy

Pathogenesis and therapies of dilated cardiomyopathy (DCM) have been discussed for a long time, but both of the ultimate answers are still unknown. In the last decade, the pathogenic role of immunological factors, such as cardiac autoimmune antibodies and cytokines, have been discussed attentively. This has led to one possible new therapy, immunoadsorption, which removes antibodies, and it has made a remarkable effect. However, there are other factors to remove. For the removal of cytokines and neurohormones, the most effective method is hemofiltration (HF). Also, double-filtration plasmapheresis (DFPP) removes immunoglobulin as well as low-density lipoprotein (LDL) and coagulation factors that may improve blood circulation, including the coronary arteries. Therefore, to eliminate all deteriorative factors, both apheresis therapies, HF and DFPP, should be performed. Due to the shortage of donor hearts, left ventricular assist systems (LVAD) have been used as a bridge to transplantation. It has now been reported that the total unloading of the left ventricle does not only maintain, but also recovers, the cardiac function, even from end-stage heart failure. However, the patients who have obtained a long-lasting recovery of cardiac function from an LVAD are still in a minority. To make this the majority, therapeutic LVAD should be combined with the apheresis therapies, DFPP and HF. We believe that this concept, a combination of HF and DFPP with therapeutic LVAD, will be the next generation of treatment that has a potential to postpone, or even avoid, heart transplantation.

Cardioprotective effects of phosphoramidon on myocardial structure and function in murine Chagas' disease

Chagas' disease is an important cause of cardiomyopathy. Endothelin-1, a vasoactive peptide has been implicated in the pathogenesis of chagasic cardiomyopathy. C57BL/6 x 129sv and CD1 mice were thus, infected with trypomastigotes of Trypanosoma cruzi (Brazil strain) and these infected mice were compared with infected mice treated with phosphoramidon. This compound inhibits endothelin-converting enzyme and neutral endopeptidases and does not affect the growth of the parasite in culture. Phosphoramidon was given in a dose of 10mg/kg for the initial 15 days post-infection None of the C57Bl/6 x 129sv mice died as a result of infection. However, there was marked myocardial inflammation and fibrosis in infected, untreated mice. The hearts of the infected, phosphoramidon-treated mice showed significantly less pathology. Cardiac magnetic resonance imaging of infected mice revealed right ventricular dilation that was less severe in those treated with phosphoramidon. Phosphoramidon-treated CD1 mice survived the acute infection. Transthoracic echocardiography demonstrated left ventricular dilation and reduced percent fractional shortening and relative wall thickness. These alterations were also attenuated as a result of phosphoramidon treatment. These data suggest that endothelin-1 contributes to the pathogenesis of chagasic cardiomyopathy and interventions that inhibit the synthesis of endothelin-1 and/or neutral endopeptidase might have a protective effect on myocardial structure and function in murine Chagas' disease.

Evaluation and prevalidation of an immunotoxicity test based on human whole-blood cytokine release

Immunotoxicology is a relatively new field in toxicology, and is one of emerging importance, because immunotoxicity appears to contribute to the development of cancer, autoimmune disorders, allergies and other diseases. At present, there is a lack of human cell-based immunotoxicity assays for predicting the toxicity of xenobiotics toward the immune system in a simple, fast, economical and reliable way. Existing immunotoxicity tests are mainly performed in animals, although species differences favour human-based testing. Whole-blood cytokine release models have attracted increasing interest, and are broadly used for pharmacological in vitro and ex vivo studies, as well as for pyrogenicity testing. We have adapted those methods for immunotoxicity testing, to permit the potency testing of immunostimulants and immunosuppressants. Following stimulation with a lipopolysaccharide or staphylococcal enterotoxin B, monocytes and lymphocytes release interleukin-1beta and interleukin-4, respectively. Thirty-one pharmaceutical compounds, with known effects on the immune system, were used to optimise and standardise the method, by analysing their effects on cytokine release. The in vitro results were expressed as IC50 values for immunosuppression, and SC(4) (fourfold increase) values for immunostimulation, and compared with therapeutic serum concentrations of the compounds in patients, and in vivo LD50 values from animal studies. The in vitro results correlated well with the in vivo data, so the test appears to reflect immunomodulation. Results were reproducible (CV = 20 +/- 5%), and the method could be transferred to another laboratory (r(2) = 0.99). We therefore propose this method for further validation and for use in immunotoxicity testing strategies.

Molecular actions of drugs that sensitize cardiac myofilaments to Ca2+

Ca(2+)-sensitizers are inotropic agents that modify the response of myofilaments to Ca2+, and are potentially valuable drugs in the treatment of heart failure. These agents have diverse chemical structures, and in some cases also have effects as inhibitors of phosphodiesterase activity. Advantages of their actions include vasodilation combined with inotropic effects. Reduction in the amounts of Ca2+ required to activate the myofilaments also lowers the oxygen consumption required for Ca2+ transport, lowers the threat of arrhythmias, and may blunt Ca(2+)-dependent transcriptional and translational mechanisms leading to hypertrophy and failure. Although diastolic abnormalities and impaired relaxation were thought to be potential undesirable effects of Ca(2+)-sensitizers, studies of hearts beating in situ indicate that this may not be a major problem. We focus here on Ca(2+)-sensitizers that act on cardiac troponin C, the Ca2+ receptor that triggers activation of the actin-myosin interaction. Structural studies have identified a unique mode of Ca2+ signaling in cardiac troponin C that should aid in targeting drugs to the heart. Moreover, identification of docking sites of Ca(2+)-sensitizers on troponin C suggest new directions for rational drug design.