Circulating interleukin-6 family cytokines and their receptors in patients with congestive heart failure

The Role of Pro-Inflammatory Cytokines in the Pathogenesis of Cardiovascular Disease

With cardiovascular disease (CVD) being a primary source of global morbidity and mortality, it is crucial that we understand the molecular pathophysiological mechanisms at play. Recently, numerous pro-inflammatory cytokines have been linked to several different CVDs, which are now often considered an adversely pro-inflammatory state. These cytokines most notably include interleukin-6 (IL-6),tumor necrosis factor (TNF)α, and the interleukin-1 (IL-1) family, amongst others. Not only does inflammation have intricate and complex interactions with pathophysiological processes such as oxidative stress and calcium mishandling, but it also plays a role in the balance between tissue repair and destruction. In this regard, pre-clinical and clinical evidence has clearly demonstrated the involvement and dynamic nature of pro-inflammatory cytokines in many heart conditions; however, the clinical utility of the findings so far remains unclear. Whether these cytokines can serve as markers or risk predictors of disease states or act as potential therapeutic targets, further extensive research is needed to fully understand the complex network of interactions that these molecules encompass in the context of heart disease. This review will highlight the significant advances in our understanding of the contributions of pro-inflammatory cytokines in CVDs, including ischemic heart disease (atherosclerosis, thrombosis, acute myocardial infarction, and ischemia-reperfusion injury), cardiac remodeling (hypertension, cardiac hypertrophy, cardiac fibrosis, cardiac apoptosis, and heart failure), different cardiomyopathies as well as ventricular arrhythmias and atrial fibrillation. In addition, this article is focused on discussing the shortcomings in both pathological and therapeutic aspects of pro-inflammatory cytokines in CVD that still need to be addressed by future studies.

Dynamics of the Levels of Interleukin 6, Its Soluble Receptor, and Soluble Glycoprotein 130 in Patients with Chronic Heart Failure and Preserved or Reduced Ejection Fraction

The features of IL-6 trans-signaling were studied in patients with heart failure with reduced (n=74) and preserved (n=31) ejection fraction (EF) during acute decompensation of HF (ADHF) and after 1 year. Patients with ADHF with reduced EF demonstrated higher levels of IL-6 and soluble glycoprotein 130 in comparison with those in patients with preserved EF: 10.18 (7.07; 16.14) pg/ml vs 6.35 (3.52; 11.00) pg/ml and 543.46 (455.37; 634.43) ng/ml vs 498.50 (408.16; 632.23) ng/ml, respectively. The levels of soluble IL-6 receptor little differed in these groups: 57.82 (47.55; 79.85) ng/ml vs 61.30 (44.97; 78.08) ng/ml. After 1 year, the levels of IL-6 in HF patients with reduced EF significantly decreased (5.36 (3.35; 8.35) pg/ml), while in patients with preserved EF, the decrease in this parameter was less pronounced (5.86 (4.05; 7.32) pg/ml), and the difference between groups disappeared. The levels of soluble glycoprotein 130 increased in both groups: 448.06 (357.74; 550.67) ng/ml vs 385.35 (344.29; 523.72) ng/ml. It should be noted that after 1 year (in stable patients), the levels of soluble IL-6 receptor increased in both groups: 65.75 (54.84; 75.39) ng/ml vs 70.81 (57.51; 82.25) ng/ml. Thus, despite the high levels of IL-6 in HF patients with reduced EF, the potential limiting IL-6 trans-signaling in these patients is higher than in patients with preserved EF.

Bioinformatics and Next-Generation Data Analysis for Identification of Genes and Molecular Pathways Involved in Subjects with Diabetes and Obesity

Background and Objectives: A subject with diabetes and obesity is a class of the metabolic disorder. The current investigation aimed to elucidate the potential biomarker and prognostic targets in subjects with diabetes and obesity. Materials and Methods: The next-generation sequencing (NGS) data of GSE132831 was downloaded from Gene Expression Omnibus (GEO) database. Functional enrichment analysis of DEGs was conducted with ToppGene. The protein-protein interactions network, module analysis, target gene-miRNA regulatory network and target gene-TF regulatory network were constructed and analyzed. Furthermore, hub genes were validated by receiver operating characteristic (ROC) analysis. A total of 872 DEGs, including 439 up-regulated genes and 433 down-regulated genes were observed. Results: Second, functional enrichment analysis showed that these DEGs are mainly involved in the axon guidance, neutrophil degranulation, plasma membrane bounded cell projection organization and cell activation. The top ten hub genes (MYH9, FLNA, DCTN1, CLTC, ERBB2, TCF4, VIM, LRRK2, IFI16 and CAV1) could be utilized as potential diagnostic indicators for subjects with diabetes and obesity. The hub genes were validated in subjects with diabetes and obesity. Conclusion: This investigation found effective and reliable molecular biomarkers for diagnosis and prognosis by integrated bioinformatics analysis, suggesting new and key therapeutic targets for subjects with diabetes and obesity.

The Role of Interleukin-6 Family Members in Cardiovascular Diseases

Cardiovascular disease is one of the main causes of human mortality. Cytokines play crucial roles in the development of cardiovascular disease. Interleukin (IL)-6 family members are a series of cytokines, including IL-6, IL-11, IL-30, IL-31, OSM, LIF, CNTF, CT-1, CT-2, and CLC, that regulate multiple biological effects. Experimental and clinical evidence shows that IL-6 family members are closely related to cardiovascular diseases such as atherosclerosis, hypertension, aortic dissection, cardiac fibrosis, and cardiomyopathy. This review mainly discusses the role of IL-6 family members in cardiovascular disease for the sake of identifying possible intervention targets for cardiovascular disease prevention and treatment.

Characteristics of Interleukin-6 Signaling in Elective Cardiac Surgery—A Prospective Cohort Study

Interleukin-6 (IL-6) can cause pro- and anti-inflammatory effects via different signaling pathways. This prospective study investigated the perioperative kinetics of IL-6, soluble IL-6 receptor (sIL-6R), and soluble glycoprotein 130 (sgp130) in elective patients undergoing cardiopulmonary bypass (CPB). IL-6, sIL-6R, and sgp130 were measured simultaneously and consecutively at 19 timepoints until the 10th postoperative day (POD). The proportion of pro- and anti-inflammatory pathways were determined by calculating sIL-6R/IL-6 and sIL-6R/sgp130 ratios. We analyzed 93 patients. IL-6 increased during surgery with reaching a plateau two hours after CPB and peaking on POD 1 (188.5 pg mL⁻¹ (IQR, 126.6; 309.2)). sIL-6R decreased at the beginning of the surgical procedure, reaching a nadir level on POD 2 (26,311 pg mL⁻¹ (IQR, 22,222; 33,606)). sgp130 dropped immediately after CPB initiation (0.13 ng mL⁻¹ (IQR, 0.12; 0.15)), followed by a continuous recovery until POD10. The sIL-6R/IL-6 ratio decreased substantially at the beginning of the procedure, reaching a nadir on POD 1 (149.7 (IQR, 82.4; 237.4)), while the sIL-6R/sgp130 ratio increased simultaneously until 6 h post CPB (0.219 (IQR 0.18; 0.27)). In conclusion, IL-6 exhibited high inter-individual variability reflecting an inhomogeneous inflammatory response. Pro-inflammatory effects and overwhelming inflammation were rare and predominantly anti-inflammatory effects were found.

Pro-inflammatory cytokines in chronic cardiac failure: state of problem

Systemic inflammation is characterized by the induction of pro-inflammatory cytokines, the increased level of which in the blood of patients with chronic heart failure (CHF) correlates with unfavorable clinical outcomes. However, it is unclear whether pro-inflammatory cytokines are the cause or the consequence of the disease progression. CHF with preserved ejection fraction and CHF with reduced ejection fraction demonstrate different inflammatory features, which suggests different degrees of pro-inflammatory pathway activation. The review deals with participation of pro-inflammatory cytokines in pathophysiological processes of CHF development, emphasizing the role of interleukin-6 activation and the effects of accompanying diseases on the course of systemic inflammation. The search for new approaches to prevention and therapy of CHF remains actual. The review presents the results of clinical trials of targeted anti-cytokine therapy which have revealed difficulties in controlling inflammation under the conditions of CHF. Identification of specific pro-inflammatory pathways in CHF pathogenesis will allow one to control inflammatory cascades, thus providing a prospective therapeutic strategy.

Interleukin-6: A Novel Target for Cardio-Cerebrovascular Diseases

Cardio-Cerebrovascular Disease is a collective term for cardiovascular disease and cerebrovascular disease, being a serious threat to human health. A growing number of studies have proved that the content of inflammatory factors or mediators determines the stability of vascular plaque and the incidence of cardio-cerebrovascular event, and involves in the process of Cardio-Cerebrovascular Diseases. Interleukin-6 is a widely used cytokine that causes inflammation and oxidative stress, which would further result in cardiac and cerebral injury. The increased expression of interleukin-6 is closely related to atherosclerosis, myocardial infarction, heart failure and ischemic stroke. It is a key risk factor for these diseases by triggering inflammatory reaction and inducing other molecules release. Therefore, interleukin-6 may become a potential target for Cardio-Cerebrovascular Diseases in the future. This paper is aimed to discuss the expression changes and pathological mechanisms of interleukin-6 in Cardio-Cerebrovascular Diseases, and to provide a novel strategy for the prevention and treatment of Cardio-Cerebrovascular Diseases.

Identification of critical molecular pathways involved in exosome-mediated improvement of cardiac function in a mouse model of muscular dystrophy

Duchenne muscular dystrophy (DMD) is a progressive disease characterized by skeletal muscle atrophy, respiratory failure, and cardiomyopathy. Our previous studies have shown that transplantation with allogeneic myogenic progenitor-derived exosomes (MPC-Exo) can improve cardiac function in X-linked muscular dystrophy (Mdx) mice. In the present study we explored the molecular mechanisms underlying this beneficial effect. We quantified gene expression in the hearts of two strains of Mdx mice (D2.B10-DmdMdx/J and Utrntm1Ked-DmdMdx/J). Two days after MPC-Exo or control treatment, we performed unbiased next-generation RNA-sequencing to identify differentially expressed genes (DEGs) in treated Mdx hearts. Venn diagrams show a set of 780 genes that were ≥2-fold upregulated, and a set of 878 genes that were ≥2-fold downregulated, in both Mdx strains following MPC-Exo treatment as compared with control. Gene ontology (GO) and protein-protein interaction (PPI) network analysis showed that these DEGs were involved in a variety of physiological processes and pathways with a complex connection. qRT-PCR was performed to verify the upregulated ATP2B4 and Bcl-2 expression, and downregulated IL-6, MAPK8 and Wnt5a expression in MPC-Exo-treated Mdx hearts. Western blot analysis verified the increased level of Bcl-2 and decreased level of IL-6 protein in MPC-Exo-treated Mdx hearts compared with control treatment, suggesting that anti-apoptotic and anti-inflammatory effects might be responsible for heart function improvement by MPC-Exo. Based on these findings, we believed that these DEGs might be therapeutic targets that can be explored to develop new strategies for treating DMD.

Decreased Cytokine Plasma Levels and Changes in T-Cell Activation Are Associated With Hemodynamic Improvement and Clinical Outcomes After Percutaneous Mitral Commissurotomy in Patients With Rheumatic Mitral Stenosis

Mitral stenosis (MS) is a consequence of rheumatic heart disease that leads to heart failure requiring mechanical intervention. Percutaneous mitral commissurotomy (PMC) is the treatment of choice for the intervention, and currently there are no soluble markers associated with hemodynamic improvement after PMC. This study aims to determine the changes in cytokine/chemokine plasma levels, as well as T cell activation after PMC, and to investigate their association with immediate hemodynamic improvement and clinical outcomes. Plasma samples from eighteen patients with well-defined MS who underwent PMC and 12 healthy controls were analyzed using BioPlex immunoassay. We observed that 16 out of the 27 (60%) molecules assessed were altered in patients' plasma pre-PMC as compared to control group. Of those, IL-1β, IL-12, IL-6, IL-4, PDGF, and CCL11 showed significant decrease after PMC. Stratifying the patients according to adverse outcome after a 28-month median follow up, we detected a significant reduction of IL-1β, IL-12, IL-6, IL-4, IFN-γ, CXCL-10, VEGF, FGF and PDGF post-PMC in patients without events, but not in those who presented adverse events during the follow-up. Patients with adverse outcomes had lower IL-10 pre-PMC, as compared to the ones without adverse events. In addition, the frequency of CD8+ activated memory cells was increased after PMC, while the frequency of CD4+ activated memory cells did not change. Our results show an association between the decrease of specific cytokines and changes in T cell activation with hemodynamic improvement post-PMC, as well as with long-term outcomes, suggesting their possible use as soluble markers for hemodynamic recovery after MS intervention.

Iron derived from autophagy-mediated ferritin degradation induces cardiomyocyte death and heart failure in mice

Heart failure is a major public health problem, and abnormal iron metabolism is common in patients with heart failure. Although iron is necessary for metabolic homeostasis, it induces a programmed necrosis. Iron release from ferritin storage is through nuclear receptor coactivator 4 (NCOA4)-mediated autophagic degradation, known as ferritinophagy. However, the role of ferritinophagy in the stressed heart remains unclear. Deletion of Ncoa4 in mouse hearts reduced left ventricular chamber size and improved cardiac function along with the attenuation of the upregulation of ferritinophagy-mediated ferritin degradation 4 weeks after pressure overload. Free ferrous iron overload and increased lipid peroxidation were suppressed in NCOA4-deficient hearts. A potent inhibitor of lipid peroxidation, ferrostatin-1, significantly mitigated the development of pressure overload-induced dilated cardiomyopathy in wild-type mice. Thus, the activation of ferritinophagy results in the development of heart failure, whereas inhibition of this process protects the heart against hemodynamic stress.

Alpha-Klotho is a novel predictor of treatment responsiveness in patients with heart failure

Heart failure is a major cause of death with an increasing population of elderly individuals. Several studies have demonstrated the involvement of soluble alpha-Klotho (sαKl) in various diseases. However, the correlation between sαKl and heart failure remains to be understood. The aim of this study is to investigate the levels and role of sαKl in patients with heart failure. Twenty-eight consecutive patients with acute heart failure (19 male, 9 female), admitted to the Osaka University Hospital from 2010 to 2018, were enrolled in this study. Mean NYHA score, left ventricular ejection fraction and BNP were 3.3, 17.0% and 588 pg/mL, respectively. SαKl significantly increased in heart failure patients. SαKl on admission were significantly higher in patients with heart failure who showed improvement after intensive treatment than that in patients who did not show improvement after the treatment. SαKl levels decreased significantly in patients who showed improvement. Interestingly, sαKl levels increased in male patients with heart failure, but not in female patients. Our data suggest that soluble αKl may be a novel biomarker for the responsiveness against treatment in patients with heart failure with reduced ejection fraction. Our findings may help developing a personalized therapy for different patients with heart failure.

The Cardiac Microenvironment Instructs Divergent Monocyte Fates and Functions in Myocarditis

Two types of monocytes, Ly6C^hi and Ly6C^lo, infiltrate the heart in murine experimental autoimmune myocarditis (EAM). We discovered a role for cardiac fibroblasts in facilitating monocyte-to-macrophage differentiation of both Ly6C^hi and Ly6C^lo cells, allowing these macrophages to perform divergent functions in myocarditis progression. During the acute phase of EAM, IL-17A is highly abundant. It signals through cardiac fibroblasts to attenuate efferocytosis of Ly6C^hi monocyte-derived macrophages (MDMs) and simultaneously prevents Ly6C^lo monocyte-to-macrophage differentiation. We demonstrated an inverse clinical correlation between heart IL-17A levels and efferocytic receptor expressions in humans with heart failure (HF). In the absence of IL-17A signaling, Ly6C^hi MDMs act as robust phagocytes and are less proinflammatory, whereas Ly6C^lo monocytes resume their differentiation into MHCII⁺ macrophages. We propose that MHCII⁺Ly6C^lo MDMs are associated with the reduction of cardiac fibrosis and prevention of the myocarditis sequalae.

Hou et al. show that cardiac fibroblasts facilitate infiltrating Ly6C^hi and Ly6C^lo monocytes to become macrophages. IL-17A trans-signaling through cardiac fibroblasts increases MerTK shedding and promotes a pro-inflammatory and pro-tissue remodeling gene expression profile in Ly6C^hi monocyte-derived macrophages. Paradoxically, IL-17A signaling through cardiac fibroblasts can substantially inhibit Ly6C^lo monocyte-to-macrophage differentiation.

Cytokine mRNA Degradation in Cardiomyocytes Restrains Sterile Inflammation in Pressure-Overloaded Hearts

BACKGROUND

Proinflammatory cytokines play an important role in the pathogenesis of heart failure. The mechanisms responsible for maintaining sterile inflammation within failing hearts remain poorly defined. Although transcriptional control is important for proinflammatory cytokine gene expression, the stability of mRNA also contributes to the kinetics of immune responses. Regnase-1 is an RNase involved in the degradation of a set of proinflammatory cytokine mRNAs in immune cells. The role of Regnase-1 in nonimmune cells such as cardiomyocytes remains to be elucidated.

METHODS

To examine the role of proinflammatory cytokine degradation by Regnase-1 in cardiomyocytes, cardiomyocyte-specific Regnase-1-deficient mice were generated. The mice were subjected to pressure overload by means of transverse aortic constriction to induce heart failure. Cardiac remodeling was assessed by echocardiography as well as histological and molecular analyses 4 weeks after operation. Inflammatory cell infiltration was examined by immunostaining. Interleukin-6 signaling was inhibited by administration with its receptor antibody. Overexpression of Regnase-1 in the heart was performed by adeno-associated viral vector-mediated gene transfer.

RESULTS

Cardiomyocyte-specific Regnase-1-deficient mice showed no cardiac phenotypes under baseline conditions, but exhibited severe inflammation and dilated cardiomyopathy after 4 weeks of pressure overload compared with control littermates. Four weeks after transverse aortic constriction, the Il6 mRNA level was upregulated, but not other cytokine mRNAs, including tumor necrosis factor-α, in Regnase-1-deficient hearts. Although the Il6 mRNA level increased 1 week after operation in both Regnase-1-deficient and control hearts, it showed no increase in control hearts 4 weeks after operation. Administration of anti-interleukin-6 receptor antibody attenuated the development of inflammation and cardiomyopathy in cardiomyocyte-specific Regnase-1-deficient mice. In severe pressure overloaded wild-type mouse hearts, sustained induction of Il6 mRNA was observed, even though the protein level of Regnase-1 increased. Adeno-associated virus 9-mediated cardiomyocyte-targeted gene delivery of Regnase-1 or administration of anti-interleukin-6 receptor antibody attenuated the development of cardiomyopathy induced by severe pressure overload in wild-type mice.

CONCLUSIONS

The degradation of cytokine mRNA by Regnase-1 in cardiomyocytes plays an important role in restraining sterile inflammation in failing hearts and the Regnase-1-mediated pathway might be a therapeutic target to treat patients with heart failure.

Integrating Pharmacokinetics Study, Network Analysis, and Experimental Validation to Uncover the Mechanism of Qiliqiangxin Capsule Against Chronic Heart Failure

Objectives: The purpose of this study was to propose an integrated strategy for investigating the mechanism of Qiliqiangxin capsule (QLQX) to treat chronic heart failure (CHF). Methods: Pharmacokinetics analysis was performed to screen the active components of QLQX using high-performance liquid chromatography-tandem mass spectrometry techniques. We then constructed the component-target network between the targets of active components in QLQX and CHF using Cytoscape. A network analysis, including topological parameters, clustering, and pathway enrichment, was established to identify the hub targets and pathways. Finally, some of the predicted hub targets were validated experimentally in human cardiac microvascular endothelial cell (HCMEC). Results: We identified 29 active components in QLQX, and 120 consensus potential targets were determined by the pharmacokinetics analysis and network pharmacology approach. Further network analysis indicated that 6 target genes, namely, VEGFA, CYP1A1, CYP2B6, ATP1A1, STAT3, and STAT4, and 10 predicted functional genes, namely, KDR, FLT1, NRP2, JAK2, EGFR, IL-6, AHR, ATP1B1, JAK1, and HIF1A, may be the primary targets regulated by QLQX for the treatment of CHF. Among these targets, VEGFA, IL-6, p-STAT3, and p-JAK2 were selected for validation in the HCMEC. The results indicated that QLQX may inhibit inflammatory processes and promote angiogenesis in CHF via the JAK/STAT signaling pathway. Conclusions: This study provides a strategy for understanding the mechanism of QLQX against CHF by combining pharmacokinetics study, network pharmacology, and experimental validation.

Cytokines in heart failure

The natural history of heart failure (HF) is not linear, because changes in the heart structure and function start long before the disease becomes clinically evident. Many different cytokines originating from intracardiac tissues (cardiomyocytes, cardiac endothelial cells, cardiac fibroblasts, and cardiac infiltrated immune cells) or extracardiac tissues (adipose tissue, gut, and lymphoid organs) have been identified in HF. Because the levels of circulating cytokines correlate with the development and severity of HF, these mediators may have both pathophysiological importance, through their ability to modulate inflammation, myocyte stress/stretch, myocyte injury and apoptosis, fibroblast activation and extracellular matrix remodeling, and utility as clinical predictive biomarkers. A greater understanding of the mechanisms mediated by the multifaceted network of cytokines, leading to distinct HF phenotypes (HF with reduced or preserved ejection fraction), is urgently needed for the development of new treatment strategies. In this chapter, all these issues were thoroughly discussed, pointing on the practical considerations concerning the clinical use of the cytokines as prognostic biomarkers and potential therapeutic targets in HF.

Causes and consequences of cardiac fibrosis in patients referred for surgical aortic valve replacement

Aims

Cardiac fibrosis is associated with left ventricular (LV) remodelling and contractile dysfunction in aortic stenosis (AS). The fibrotic process in this condition is still unclear. The aim of this study was to determine the role of both local and systemic inflammation as underlying mechanisms of LV fibrosis and contractile dysfunction. The diagnostic values of 2D‐strain echocardiography and serum biomarkers in the evaluation of cardiac fibrosis in this condition were assessed through correlation analyses.

Methods and results

Patients with AS referred for surgical valve replacement were prospectively and consecutively included. They all had a comprehensive echocardiography including 2D strain. Blood samples were collected to measure cytokines and inflammatory biomarkers using Luminex bead‐based assays. A per‐surgical myocardial biopsy of the basal antero‐septal segment (S1) was performed. Serial sections of each biopsy were stained with Sirius red. Digital image analysis was used to quantify fibrosis. Immunostainings using specific antibodies against macrophage, glycoprotein (gp) 130, and interleukin 6 (IL‐6) were also performed. Patients were divided into tertiles reflecting the severity of fibrosis: mild, moderate, and severe load (TF1 to TF3). The mean age of the 58 included patients was 73 ± 11 years. Twenty‐four (43%) were in New York Heart Association III–IV. Mean aortic valve area was 0.8 ± 0.2 cm². Mean aortic stenosis peak velocity and mean gradient were respectively 4.5 ± 0.8 m/s and 54 ± 15 mmHg. The mean LV ejection fraction was 54 ± 12%, and the global LV longitudinal strain was −15 ± 4%. The mean S1 strain, corresponding to the biopsied region, was −10 ± 6% and was strongly correlated to fibrosis load (R = 0.83, P < 0.0001). TF3 was associated with higher mortality (P = 0.009), higher serum C‐reactive protein and IL‐6, and lower gp130 compared with the other tertiles (P < 0.05). IL‐6 and gp130 were expressed in the heart and respectively in the plasma membrane of macrophages and in the cytoplasm of both macrophages and cardiomyocytes. During follow‐up, three patients died and were all in the third fibrosis tertile.

Conclusions

We found a positive correlation between elevated inflammatory markers and degree of fibrosis load. These two parameters were associated with worse outcomes in patients with severe AS. Our results may be of interest especially in patients for whom a transcatheter aortic valve implantation is indicated and myocardial biopsy is not possible. Strategies aiming at preventing inflammation might be considered to decrease or limit the progression of cardiac fibrosis in patients followed for AS.

Interleukin 6 Knockout Inhibits Aging-Related Accumulation of p53 in the Mouse Myocardium

Interleukin 6 (IL6) and p53 are linked by mutual regulatory mechanisms and are both upregulated in aging. The aim of this study was to evaluate the effects of aging and IL6 on expression of p53 in the mouse heart. Male C57BL6/J wild-type and IL6 knockout mice at the age of 4-5 months (young adult) and 24-30 months (old) were used. Myocardial expression of proteins such as p53, p21, Mdm2, and phospho-Akt/Akt was estimated using Western blotting and expression of p53 and p21 mRNA using real-time polymerase chain reaction. Expression of p53 protein was lower in IL6 knockout hearts than in wild-type hearts. Aging caused significant upregulation of p53 protein level; however, it was significantly higher in old wild-type hearts than in old IL6 knockout hearts (p < .05). Similar p53 mRNA levels in all groups implied IL6 influence on age-related proteasomal degradation of p53. Localization of p53 mainly in the extranuclear compartment and lack of p21 upregulation in aged hearts may suggest quenched transcriptional activity of p53 despite increased abundance of p53. We conclude that lack of IL6 attenuates expression of p53 protein in the hearts of young mice and diminishes its accumulation with aging by post-transcriptional mechanisms; however, this is not related to altered phenotype of aging heart.

Soluble glycoprotein 130 is inversely related to severity of coronary atherosclerosis

PURPOSE

Recent studies indicate that the effects of interleukin 6 (IL-6) realized via soluble IL-6 receptor (sIL-6R) facilitate the development of various pathological processes. Soluble gp130 (sgp130) is a naturally occurring inhibitor of signal transduction via this pathway. In this study, we assessed the relationship between circulating levels of IL-6, sIL-6R and sgp130 and severity of coronary atherosclerosis in patients with stable coronary artery disease (CAD).

METHODS

Plasma levels of IL-6, sIL-6R and sgp130 were measured in patients with atherosclerotic coronary lesions (n = 128, group 1) and with intact coronary arteries (n = 48, group 2). The severity of coronary atherosclerosis was evaluated by the number of affected arteries and by Gensini Score index.

RESULTS

Circulating IL-6 levels in group 1 were significantly higher than those in group 2. The levels of sIL-6R did not differ considerably in both the groups. The levels of sgp130 in group 1 were significantly lower than in group 2. A negative correlation has been revealed between sgp130 levels and the number of affected coronary arteries and Gensini Score index.

CONCLUSIONS

Serum concentration of sgp130 in patients with stable CAD is inversely related to severity of coronary damage. Low sgp130 level may serve as an additional indicator of coronary atherosclerosis severity.

Interleukin-6 signaling in patients with chronic heart failure treated with cardiac resynchronization therapy

INTRODUCTION

Increased expression of interleukin-6 (IL-6) has been described in left ventricular dysfunction in the course of chronic heart failure. Cardiac resynchronization therapy (CRT) is a unique treatment method that may reverse the course of chronic heart failure (CHF) with reduced ejection fraction (HF-REF). We aimed to evaluate the IL-6 system, including soluble IL-6 receptor (sIL-6R) and soluble glycoprotein 130 (sgp130), in HF-REF patients, with particular emphasis on CRT effects.

MATERIAL AND METHODS

The study enrolled 88 stable HF-REF patients (63.6 ±11.1 years, 12 females, EF < 35%) and 35 comorbidity-matched controls (63.5 ±9.8 years, 7 females). Forty-five HF-REF patients underwent CRT device implantation and were followed up after 6 months. Serum concentrations of IL-6, sIL-6R and sgp130 were determined using ELISA kits.

RESULTS

The HF-REF patients had higher IL-6 (median: 2.6, IQR: 1.6-3.8 vs. 2.1, IQR: 1.4-3.1 pg/ml, p = 0.03) and lower sIL-6R concentrations compared to controls (median: 51, IQR: 36-64 vs. 53. IQR 44-76 ng/ml, p = 0.008). There was no significant difference between sgp130 concentrations. In the HF-REF group IL-6 correlated negatively with EF (r = -0.5, p = 0.001) and positively with BNP (r = 0.5, p = 0.008) and CRP concentrations (r = 0.4, p = 0.02). Patients who presented a positive response after CRT showed a smaller change of sIL-6R concentration compared to nonresponders (ΔsIL-6R: -0.2 ±7.1 vs. 7 ±14 ng/ml; p = 0.04).

CONCLUSIONS

HF-REF patients present higher IL-6 and lower sIL-6R levels. IL-6 concentration reflects their clinical status. CRT-related improvement of patients' functional status is associated with a smaller change of sIL-6R concentration in time.

Preadmission Use of Calcium Channel Blockers and Outcomes After Hospitalization With Pneumonia: A Retrospective Propensity-Matched Cohort Study

In sepsis, an overwhelming immune response, as mediated by the release of various inflammatory mediators, can lead to shock, multiple organ damage, and even death. Pneumonia is the leading cause of sepsis. In animal septic models, sepsis could induce uncontrolled calcium (Ca) leaking, raising cytosolic Ca to a toxic level, causing irreversible cellular injuries and organ failure. All types of calcium channel blockers (CCBs), by inhibiting Ca influx, have been shown to decrease overall mortality in various septic animal models. However, to our best knowledge, no clinical study had been conducted to investigate the beneficial effect(s) of CCBs in sepsis. We conducted a retrospective propensity-matched cohort study after screening 2214 patients hospitalized for pneumonia from year 2012 to 2014 at our institution. We identified 387 preadmission CCB users and 387 nonusers by propensity score matching. Logistic regression analysis was then used to determine the association between preadmission CCB use and outcomes in pneumonia. Our study showed that the odds for development of severe sepsis was significantly lower in the CCB user group [odds ratio (OR), 0.466; 95% confidence interval (CI), 0.311-0.697; P = 0.002]. Preadmission CCB use was associated with a lower risk of contracting bacteremia (OR, 0.498; 95% CI, 0.262-0.99; P = 0.0327), lower risk of acute respiratory insufficiency (OR, 0.573; 95% CI, 0.412-0.798; P = 0.001), lower risk of intensive care unit admission (OR, 0.602; 95% CI, 0.432-0.840; P = 0.0028). In conclusion, our study suggested preadmission CCB use was associated with a reduction in the risks of development of respiratory insufficiency, bacteremia, and severe sepsis in patients admitted to the hospital with pneumonia.

Interleukin 6 regulates psoriasiform inflammation-associated thrombosis

Psoriasis patients are at increased risk of heart attack and stroke and have elevated MRP8/14 levels that predict heart attack. The KC-Tie2 psoriasiform mouse model exhibits elevated MRP8/14 and is prothrombotic. Mrp14^-/- mice, in contrast, are protected from thrombosis, but, surprisingly, KC-Tie2xMrp14^-/- mice remain prothrombotic. Treating KC-Tie2xMrp14^-/- mice with anti-IL-23p19 antibodies reversed the skin inflammation, improved thrombosis, and decreased IL-6. In comparison, IL-6 deletion from KC-Tie2 animals improved thrombosis despite sustained skin inflammation, suggesting that thrombosis improvements following IL-23 inhibition occur secondary to IL-6 decreases. Psoriasis patient skin has elevated IL-6 and IL-6 receptor is present in human coronary atheroma, supporting a link between skin and distant vessel disease in patient tissue. Together, these results identify a critical role for skin-derived IL-6 linking skin inflammation with thrombosis, and shows that in the absence of IL-6 the connection between skin inflammation and thrombosis comorbidities is severed.

Effect of adenovirus mediated β2-AR overexpression on IL-10 level secreted by cardiomyocytes of heart failure rats

The effect of β₂-adrenergic receptor (AR) overexpression on interleukin (IL)-10 content secreted by cardiomyocytes of heart failure (HF) rats was investigated. A rat model of chronic HF was established by partially banding abdominal aorta and the cardiomyocytes were isolated with collagenase II. The cardiomyocytes were then transfected with adenovirus type 5-ADRβ₂-enhanced green fluorescent protein (EGFP) for 48 h to observe the changes of β₂-AR protein expression using western blot analysis. The IL-10 level was detected by ELISA. The experiment was divided into seven groups: Control, HF, HF+EGFP, HF+β₂, sham, sham+EGFP and sham+β₂ groups. Compared with the sham-operated group, left ventricular diastolic dimension, and left ventricular systolic dimension were increased (P<0.05), whereas ejection fraction and fractional shortening were decreased (P<0.05) in the HF group. Compared with the sham group, the cardiomyocyte survival rate of the HF group was significantly reduced (P<0.05). Compared with the control or sham group, the β₂-AR protein level of the HF group showed no significant differences (P>0.05). Compared with the HF and HF+EGFP groups, the expression of β₂-AR protein of cardiomyocytes was increased in the HF+β₂ group (P<0.05). Compared with the sham group, IL-10 content secreted by cardiomyocytes in the HF group was increased (P<0.05). Compared with the HF and HF+EGFP groups, IL-10 content in the HF+β₂ group was increased significantly (P<0.05). In conclusion, the concentration of IL-10 secreted by cardiomyocytes of HF rats was increased. The overexpression of β₂-AR in the cardiomyocytes of HF rats was able to enhance the secretion of IL-10.

Circulating Levels of IL-6 Receptor and gp130 and Long-Term Clinical Outcomes in ST-Elevation Myocardial Infarction

BACKGROUND

Reports on soluble interleukin-6 (IL-6) receptor (sIL-6R) and glycoprotein 130 (sgp130) in ST-elevation myocardial infarction (STEMI) are few and include a small number of patients. The aim of this study was to investigate the possible association between levels of these biomarkers in the acute phase of STEMI and future cardiovascular events.

METHODS AND RESULTS

Circulating IL-6, sgp130, sIL-6R, and C-reactive protein (CRP) were measured in 989 STEMI patients during 2007-2011, and cardiovascular events were recorded during follow-up. The primary endpoint was composite of all-cause mortality, myocardial infarction, stroke, unscheduled revascularization, or rehospitalization for heart failure. Cox regression models were used to estimate hazard ratios (HRs) for cardiovascular events in relation to biomarker levels. Median levels of sIL-6R, sgp130, IL-6, and CRP measured 24 hours (median) after symptom onset were 39.2 ng/mL, 240 ng/mL, 18.8 pg/mL, and 13.7 mg/L, respectively. During a median follow-up time of 4.6 years, 200 patients (20.2%) experienced a primary endpoint, and 82 patients (8.3%) died. Patients with sIL-6R levels in the upper quartile (>47.7 ng/mL) had significantly higher risk of future adverse events (primary endpoint) and mortality compared to patients with lower levels (adjusted HR, 1.54 [1.08, 2.21]; P=0.02 and 1.81 [1.04, 3.18]; P=0.04, respectively). Neither IL-6 nor sgp130 levels were related to future events, but patients with CRP levels in the upper quartile (>31.5 mg/L) had higher risk of death.

CONCLUSION

High levels of sIL-6R were associated with future cardiovascular events and mortality in STEMI patients, suggesting an important role of the IL-6 signaling system.

Deletion of interleukin-6 prevents cardiac inflammation, fibrosis and dysfunction without affecting blood pressure in angiotensin II-high salt-induced hypertension

OBJECTIVE

Inflammation has been proposed as a key component in the development of hypertension and cardiac remodeling associated with different cardiovascular diseases. However, the role of the proinflammatory cytokine interleukin-6 in the chronic stage of hypertension is not well defined. Here, we tested the hypothesis that deletion of interleukin-6 protects against the development of hypertension, cardiac inflammation, fibrosis, remodeling and dysfunction induced by high salt diet and angiotensin II (Ang II).

METHODS

Male C57BL/6J and interleukin-6-knock out (KO) mice were implanted with telemetry devices for blood pressure (BP) measurements, fed a 4% NaCl diet, and infused with either vehicle or Ang II (90 ng/min per mouse subcutaneously) for 8 weeks. We studied BP and cardiac function by echocardiography at baseline, 4 and 8 weeks.

RESULTS

Myocyte cross-sectional area (MCSA), macrophage infiltration, and myocardial fibrosis were also assessed. BP increased similarly in both strains when treated with Ang II and high salt (Ang II-high salt); however, C57BL/6J mice developed a more severe decrease in left ventricle ejection fraction, fibrosis, and macrophage infiltration compared with interleukin-6-KO mice. No differences between strains were observed in MCSA, capillary density and MCSA to capillary density ratio.

CONCLUSION

In conclusion, absence of interleukin -6 did not alter the development of Ang II-high salt-induced hypertension and cardiac hypertrophy, but it prevented the development of cardiac dysfunction, myocardial inflammation, and fibrosis. This indicates that interleukin-6 plays an important role in hypertensive heart damage but not in the development of hypertension.

Anti-Fibrotic Effects of Class I HDAC Inhibitor, Mocetinostat Is Associated with IL-6/Stat3 Signaling in Ischemic Heart Failure

BACKGROUND

Recent studies have linked histone deacetylases (HDAC) to remodeling of the heart and cardiac fibrosis in heart failure. However, the molecular mechanisms linking chromatin remodeling events with observed anti-fibrotic effects are unknown. Here, we investigated the molecular players involved in anti-fibrotic effects of HDAC inhibition in congestive heart failure (CHF) myocardium and cardiac fibroblasts in vivo.

METHODS AND RESULTS

MI was created by coronary artery occlusion. Class I HDACs were inhibited in three-week post MI rats by intraperitoneal injection of Mocetinostat (20 mg/kg/day) for duration of three weeks. Cardiac function and heart tissue were analyzed at six week post-MI. CD90+ cardiac fibroblasts were isolated from ventricles through enzymatic digestion of heart. In vivo treatment of CHF animals with Mocetinostat reduced CHF-dependent up-regulation of HDAC1 and HDAC2 in CHF myocardium, improved cardiac function and decreased scar size and total collagen amount. Moreover, expression of pro-fibrotic markers, collagen-1, fibronectin and Connective Tissue Growth Factor (CTGF) were reduced in the left ventricle (LV) of Mocetinostat-treated CHF hearts. Cardiac fibroblasts isolated from Mocetinostat-treated CHF ventricles showed a decrease in expression of collagen I and III, fibronectin and Timp1. In addition, Mocetinostat attenuated CHF-induced elevation of IL-6 levels in CHF myocardium and cardiac fibroblasts. In parallel, levels of pSTAT3 were reduced via Mocetinostat in CHF myocardium.

CONCLUSIONS

Anti-fibrotic effects of Mocetinostat in CHF are associated with the IL-6/STAT3 signaling pathway. In addition, our study demonstrates in vivo regulation of cardiac fibroblasts via HDAC inhibition.

The varying faces of IL-6: From cardiac protection to cardiac failure

IL6 is a pleiotropic cytokine that is made in response to perturbations in homeostasis. IL6 becomes elevated in the acute response to host injury and can activate immune cells, direct immune cell trafficking, signal protective responses in local tissue, initial the acute phase response or initiate wound healing. In the short term this proinflammatory response is protective and limits host damage. It is when this acute response remains chronically activated that IL6 becomes pathogenic to the host. Chronically elevated IL6 levels lead to chronic inflammation and fibrotic disorders. The heart is a tissue where this temporal regulation of IL6 is very apparent. Studies from myocardial infarction show how short-term IL6 signaling can protect and preserve the heart tissue in response to acute damage, where long term IL6 signaling or an over-production of IL6R protein plays a causal role in cardiovascular disease. Thus, IL6 can be both protective and pathogenic, depending on the kinetics of the host response.

Interleukin-6 signaling, soluble glycoprotein 130, and inflammation in heart failure

Both experimental and clinical evidence accumulated over the last couple of decades has linked inflammatory activation to the initiation and progression of chronic heart failure (HF). Circulating levels of inflammatory mediators are associated with cardiac function and inform risk prediction in patients, but the effect of anti-inflammatory therapy in HF remains uncertain. Interleukin (IL)-6 type cytokines are central to the inflammatory response, and convey their signals through the ubiquitously expressed glycoprotein (gp) 130 receptor subunit. IL-6-type/gp130 signaling therefore represents an inflammatory nexus, with inherent potential for disease modification. This review focuses on the current knowledge of IL-6/gp130 signaling in relation to HF, with a particular emphasis on the role of soluble gp130 (sgp130), a signaling pathway modulator. Biological aspects of sgp130 and IL-6 signaling are discussed, as are potential novel therapeutic approaches to modulate this central inflammatory signaling pathway.

Glycoprotein 130 polymorphism predicts soluble glycoprotein 130 levels

OBJECTIVE

Interleukin-6 (IL-6) is a key cytokine in inflammatory diseases. It exerts its biological function via binding to a homodimer of its signal transducer glycoprotein 130 (gp130). Soluble gp130 (sgp130) is the natural inhibitor of IL-6 trans-signalling. The aim of this study was to test a possible influence of the gp130 genotype on sgp130 serum levels.

MATERIAL AND METHODS

In two separate populations, subjects were genotyped for the gp130 polymorphism G148C. Sgp130, IL-6 and soluble interleukin-6 receptor (sIL-6R) levels were measured. The OSLO population consisted of 546 male subjects at high risk for CAD. The VIENNA population consisted of 299 male subjects with angiographically proven CAD.

RESULTS

In the OSLO population, 124 (22.7%) subjects were hetero- or homozygote for the rare C allele. Individuals carrying the polymorphism had significantly higher levels of sgp130. In a multivariate linear regression model this association remained significant (adjusted p=0.001). In the VIENNA population, 48 (16.1%) subjects were hetero- or homozygote for the rare C allele. Consistent with the former study, sgp130 levels were significantly higher in carriers of the polymorphism compared to wildtype carriers (adjusted p=0.038). In the VIENNA population, sgp130 levels were significantly higher in diabetic patients. In the OSLO population, sgp130 was higher in patients with increased body mass index and in smokers (p<0.05).

CONCLUSIONS

Sgp130 serum levels are significantly higher in subjects carrying the gp130 polymorphism G148C compared to wildtype carriers. This finding proposes a possible genetical influence on sgp130 levels which may alter individual coping mechanisms in inflammatory diseases.

IL-6 signalling in patients with acute ST-elevation myocardial infarction

Cytokines of the IL-6 family have been related to infarct size and prognosis in patients with myocardial infarction. The aims of the present study were to elucidate possible associations between myocardial necrosis and left ventricular impairment and members of the IL-6 transsignalling system including soluble (s) IL-6R and (s) glycoprotein 130 (sgp130) in patients with ST-elevation myocardial infarction (STEMI) treated with primary PCI. In blood samples from 1028 STEMI patients, collected in-hosptial, we found significant correlations between peak TnT and IL-6 and CRP (p < 0.001, all) and between IL-6 and CRP and LV ejection fraction and NT-proBNP (p < 0.001, all). On the contrary, no significant associations were found between peak TnT and sgp130 or sIL-6R. Furthermore sgp130 was significantly elevated in diabetic patients and also associated with the glucometabolic state. In conclusion, circulating levels of IL-6 and CRP, but not the soluble forms of the receptor (sIL-6R) or the receptor signalling subunit (sgp130) were associated with the extent of myocardial necrosis. The biological importance of the IL-6/gp130-mediated signalling pathways in patients with acute myocardial infarction and dysglycemia should be further elucidated.

LIF and the heart: just another brick in the wall?

Multiple studies have shown that the cytokine leukemia inhibitory factor (LIF) is protective of the myocardium in the acute stress of ischemia-reperfusion. All three major intracellular signaling pathways that are activated by LIF in cardiac myocytes have been linked to actions that protect against oxidative stress and cell death, either at the level of the mitochondrion or via nuclear transcription. In addition, LIF has been shown to contribute to post-myocardial infarction cardiac repair and regeneration, by stimulating the homing of bone marrow-derived cardiac progenitors to the injured myocardium, the differentiation of resident cardiac stem cells into endothelial cells, and neovascularization. Whether LIF offers protection to the heart under chronic stress such as hypertension-induced cardiac remodeling and heart failure is not known. However, mice with cardiac myocyte restricted knockout of STAT3, a principal transcription factor activated by LIF, develop heart failure with age, and cardiac STAT3 levels are reported to be decreased in heart failure patients. In addition, endogenously produced LIF has been implicated in the cholinergic transdiffrentiation that may serve to attenuate sympathetic overdrive in heart failure and in the peri-infarct region of the heart after myocardial infarction. Surprisingly, therapeutic strategies to exploit the beneficial actions of LIF on the injured myocardium have received scant attention. Nor is it established whether the purported so-called adverse effects of LIF observed in isolated cardiac myocytes have physiological relevance in vivo. Here we present an overview of the actions of LIF in the heart with the goal of stimulating further research into the translational potential of this pleiotropic cytokine.

Soluble Glycoprotein 130 Predicts Fatal Outcomes in Chronic Heart Failure

Background—

Glycoprotein 130 (gp130) is the common signal-transducing receptor subunit of the interleukin-6 (IL-6) family, which may be involved in the progression of heart failure (HF). We hypothesized that soluble gp130 would provide prognostic information beyond that of IL-6 in a population with HF from the Controlled Rosuvastatin Multinational Trial in Heart Failure (CORONA).

Methods and Results—

The associations of soluble gp130 and IL-6 with morbidity, mortality, and mode of death were assessed by immunoassays in a subset of 1452 patients enrolled in the CORONA trial, which included patients with HF, aged ≥60 years, in New York Heart Association classes II to IV, who had ischemic heart disease and a reduced left ventricular ejection fraction. In multivariable analyses, including C-reactive protein, IL-6, troponin T, and N-terminal pro-B-type natriuretic peptide, elevated soluble gp130 (fifth quintile versus all lower quintiles) was associated with all-cause mortality (hazard ratio, 1.47 [1.11–1.93]; P =0.006), cardiovascular mortality (hazard ratio, 1.38 [1.01–1.87]; P =0.042), and death from worsening HF (hazard ratio, 1.85 [1.09–3.14]; P =0.002), but not with the primary end point (composite of death from cardiovascular causes, nonfatal myocardial infarction, and nonfatal stroke; hazard ratio, 1.12 [0.84–1.50]; P =0.44). Plasma IL-6 was not associated with outcomes in multivariable analyses.

Conclusions—

Marked elevations in soluble gp130 are associated with total and cardiovascular mortality, as well as deaths from worsening HF, in elderly patients with HF of ischemic cause

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00206310.

Pressure overload-induced cardiac remodeling and dysfunction in the absence of interleukin 6 in mice

Congestive heart failure is associated with increased expression of pro-inflammatory cytokines, and the levels of these cytokines correlate with heart failure severity and prognosis. Chronic interleukin 6 (IL-6) stimulation leads to left ventricular (LV) hypertrophy and dysfunction, and deletion of IL-6 reduces LV hypertrophy after angiotensin II infusion. In this study, we tested the hypothesis that IL-6 deletion has favorable effects on pressure-overloaded hearts. We performed transverse aortic constriction on IL-6-deleted (IL6KO) mice and C57BL/6J mice (CON) to induce pressure overload. Pressure overload was associated with similar LV hypertrophy, dilation, and dysfunction in CON and IL6KO mice. Re-activation of the fetal gene program was also similar in pressure-overloaded CON and IL6KO mice. There were no differences between CON and IL6KO mice in LV fibrosis or expression of extracellular matrix proteins after pressure overload. In addition, no group differences in apoptosis or autophagy were seen. These data indicate that IL-6 deletion does not block LV remodeling and dysfunction induced by pressure overload. Attenuated content of IL-11 appears to be a compensatory mechanism for IL-6 deletion in pressure-overloaded hearts. We infer from these data that limiting availability of IL-6 alone is not sufficient to attenuate LV remodeling and dysfunction in failing hearts.

Absence of SOCS3 in the cardiomyocyte increases mortality in a gp130-dependent manner accompanied by contractile dysfunction and ventricular arrhythmias

BACKGROUND

Suppressor of cytokine signaling-3 (SOCS3) is a key negative-feedback regulator of the gp130 receptor that provides crucial signaling for cardiac hypertrophy and survival; however, an in vivo role of SOCS3 regulation on cardiac gp130 signaling remains obscure.

METHODS AND RESULTS

We generated cardiac-specific SOCS3 knockout (SOCS3 cKO) mice. These mice showed increased activation of gp130 downstream signaling targets (STAT3, ERK1/2, AKT, and p38) from 15 weeks of age and developed cardiac dysfunction from approximately 25 weeks of age with signs of heart failure. Surprisingly, SOCS3 cKO failing hearts had minimal histological abnormalities with intact myofibril ultrastructure. In addition, Ca(2+) transients were significantly increased in SOCS3 cKO failing hearts compared with wild-type hearts. We also found that Ser23/24 residues of troponin I were hypophosphorylated in SOCS3 cKO hearts before the manifestation of cardiac dysfunction. These data suggested the presence of abnormalities in myofilament Ca(2+) sensitivity in SOCS3 cKO mice. In addition to the contractile dysfunction, we found various ventricular arrhythmias in SOCS3 cKO nonfailing hearts accompanied by a sarcoplasmic reticulum Ca(2+) overload. To determine the contribution of gp130 signaling to the cardiac phenotype that occurs with SOCS3 deficiency, we generated cardiac-specific gp130 and SOCS3 double KO mice. Double KO mice lived significantly longer and had different histological abnormalities when compared with SOCS3 cKO mice, thus demonstrating the importance of gp130 signaling in the SOCS3 cKO cardiac phenotype.

CONCLUSIONS

Our results demonstrate an important role of SOCS3 regulation on cardiac gp130 signaling in the pathogenesis of contractile dysfunction and ventricular arrhythmias.

Glycoprotein 130 cytokine signal as a therapeutic target against cardiovascular diseases

Postnatal cardiomyocytes have only limited capacity of proliferation. Therefore, the myocardium is intrinsically equipped with cardioprotective machineries and protects itself from pathological stresses. One of the most important cardioprotective systems is the signal network of autocrine/paracrine factors, including neurohumoral factors, growth factors, and cytokines. In this review, we focus on the roles of interleukin-6 (IL-6) family cytokines, also known as glycoprotein 130 (gp130) cytokines, in cardioprotection. These cytokines make a complex with their specific cytokine receptor α-subunits. The cytokine-receptor α-subunit complex binds to gp130, a common receptor of the IL-6 family, followed by the activation of JAK/STAT, ERK, and PI3 kinase/Akt pathways. In cardiomyocytes, signals through gp130 promote cell survival and angiogenesis through the JAK/STAT pathway. Activation of gp130 in cardiac stem cells induces their endothelial transdifferentiation, leading to neovascularization. Recently, accumulating evidence has revealed that altered JAK/STAT activity is associated with heart failure, suggesting that the JAK/STAT pathway is a therapeutic target against cardiovascular diseases. Interestingly, activation of the JAK/STAT pathway with interleukin-11 (IL-11) exhibits preconditioning effects in ischemia/reperfusion model. Moreover, IL-11 treatment after coronary ligation prevents cardiac remodeling through the JAK/STAT pathway. Since IL-11 is used for patients with thrombocytopenia, we propose that IL-11 is a candidate cytokine clinically available for cardioprotection therapy.

The gp130 receptor cytokine family: regulators of adipocyte development and function

Gp130 cytokines are involved in the regulation of numerous biological processes, including hematopoiesis, immune response, inflammation, cardiovascular action, and neuronal survival. These cytokines share glycoprotein 130 as a common signal transducer in their receptor complex and typically activate STAT3. Most gp130 cytokines have paracrine or endocrine actions, and their levels can be measured in circulation in rodents and humans. In recent years, various laboratories have conducted studies to demonstrate that gp130 cytokines can modulate adipocyte development and function. Therefore, these studies suggest that some gp130 cytokines may be viable anti-obesity therapeutics. In this review, we will summarize the reported effects of gp130 cytokines on adipocyte differentiation and adipocyte function. In addition, the modulation of gp130 cytokines in conditions of obesity, insulin resistance, and Type 2 diabetes will be presented.

Gp130 cytokines exert differential patterns of crosstalk in adipocytes both in vitro and in vivo

Glycoprotein 130 (Gp130) cytokines are involved in the regulation of numerous biological processes, including hematopoiesis, immune response, inflammation, cardiovascular action, and neuronal survival. These cytokines share gp130 as a common signal transducer in their receptor complex and typically activate signal transducer and activator of transcription (STAT) 3. Studies have shown that several gp130 cytokines have differential effects on both adipogenesis and insulin-stimulated glucose uptake. Yet, the complex interactions of these cytokines in adipose tissue have not been studied. Gp130 cytokines are differentially regulated in multiple tissues due to the presence of additional receptor components that are required for signaling, including the leukemia inhibitory factor receptor (LIFR). Previous studies from our laboratory highlighted the ability of specific gp130 cytokines to crosstalk in adipocytes that correlated with LIFR degradation. Crosstalk is defined as the ability of one cytokine to modulate the signaling of another cytokine. Our novel studies reveal that white adipose tissue is highly responsive to gp130 cytokines, and we provide the first evidence that these cytokines can exert inhibitory crosstalk in adipose tissue in vivo. Moreover, several gp130 cytokines that use the LIFR, including cardiotrophin-1 (CT-1), LIF, and human oncostatin M (hOSM), can alter the subsequent signaling of other family members in adipocytes both in vitro and in vivo. Our data also show that murine OSM and neuropoietin do not crosstalk in the same manner as other gp130 cytokines, which likely results from their inability to activate the LIFR. Overall, we have observed distinctive patterns of crosstalk signaling by gp130 cytokines in adipocytes in vitro and in vivo and demonstrate the crosstalk is not dependent on new protein synthesis or extracellular-signal-regulated kinase activation.

When are pro-inflammatory cytokines SAFE in heart failure?

The cytokine hypothesis presently suggests that an excessive production of pro-inflammatory cytokines, such as tumour necrosis factor alpha (TNF) and interleukin 6 (IL6), contributes to the pathogenesis of heart failure. The concept, successfully proved in genetically modified animal models, failed to translate to humans. Recently, accumulation of apparently paradoxical experimental data demonstrates that, under certain conditions, production of pro-inflammatory cytokines can initiate the activation of a pro-survival cardioprotective signalling pathway. This novel path that involves the activation of a transcription factor, signal transducer and activator of transcription 3 (STAT3), has been termed the survival activating factor enhancement (SAFE) pathway. In this review, we will discuss whether targeting the SAFE pathway may be considered as a preventive and/or therapeutic measure for the treatment of heart failure.

TGF-beta, IL-6, IL-17 and CTGF direct multiple pathologies of chronic cardiac allograft rejection

Cardiac transplantation is an effective treatment for heart failure refractive to therapy. Although immunosuppressive therapeutics have increased first year survival rates, chronic rejection remains a significant barrier to long-term graft survival. Chronic rejection manifests as patchy interstitial fibrosis, vascular occlusion and progressive loss of graft function. Recent evidence from experimental and patient studies suggests that the development of cardiomyocyte hypertrophy is another hallmark of chronic cardiac allograft rejection. This pathologic hypertrophy is tightly linked to the immune cytokine IL-6, which promotes facets of chronic rejection in concert with TGF-beta and IL-17. These factors potentiate downstream mediators, such as CTGF, which promote the fibrosis associated with the disease. In this article, we summarize contemporary findings that have revealed several elements involved in the induction and progression of chronic rejection of cardiac allografts. Further efforts to elucidate the interplay between these factors may direct the development of targeted therapies for this disease.

The dynamics of fibroblast-myocyte-capillary interactions in the heart

In the heart, electrical, mechanical, and chemical signals create an environment essential for normal cellular responses to developmental and pathologic cues. Communication between fibroblasts, myocytes, and endothelial cells, as well as the extracellular matrix, are critical to fluctuations in heart composition and function during normal development and pathology. Recent evidence suggests that cytokines play a role in cell-cell signaling in the heart. Indeed, we find that interactions between myocytes and cardiac fibroblasts results in increased interleukin-6 and tumor necrosis factor-alpha secretion. We also used confocal and transmission electron microscopy to observe close relationships and possible direct communication between these cells in vivo. Our results highlight the importance of direct cell-cell communication in the heart, and indicate that interactions between fibroblasts, myocytes, and capillary endothelium results in differential cytokine expression. Studying these cell-cell interactions has many implications for the process of cardiac remodeling and overall heart function during development and cardiopathology.

Heart failure causes cholinergic transdifferentiation of cardiac sympathetic nerves via gp130-signaling cytokines in rodents

Although several cytokines and neurotrophic factors induce sympathetic neurons to transdifferentiate into cholinergic neurons in vitro, the physiological and pathophysiological roles of this remain unknown. During congestive heart failure (CHF), sympathetic neural tone is upregulated, but there is a paradoxical reduction in norepinephrine synthesis and reuptake in the cardiac sympathetic nervous system (SNS). Here we examined whether cholinergic transdifferentiation can occur in the cardiac SNS in rodent models of CHF and investigated the underlying molecular mechanism(s) using genetically modified mice. We used Dahl salt-sensitive rats to model CHF and found that, upon CHF induction, the cardiac SNS clearly acquired cholinergic characteristics. Of the various cholinergic differentiation factors, leukemia inhibitory factor (LIF) and cardiotrophin-1 were strongly upregulated in the ventricles of rats with CHF. Further, LIF and cardiotrophin-1 secreted from cultured failing rat cardiomyocytes induced cholinergic transdifferentiation in cultured sympathetic neurons, and this process was reversed by siRNAs targeting Lif and cardiotrophin-1. Consistent with the data in rats, heart-specific overexpression of LIF in mice caused cholinergic transdifferentiation in the cardiac SNS. Further, SNS-specific targeting of the gene encoding the gp130 subunit of the receptor for LIF and cardiotrophin-1 in mice prevented CHF-induced cholinergic transdifferentiation. Cholinergic transdifferentiation was also observed in the cardiac SNS of autopsied patients with CHF. Thus, CHF causes target-dependent cholinergic transdifferentiation of the cardiac SNS via gp130-signaling cytokines secreted from the failing myocardium.

gp130-mediated pathway and heart failure

Binding of ligands to gp130 activates at least three different downstream signaling pathways: the signal transducer and activator of transcription (STAT), the Src-homology tyrosine phosphatase 2-ras-MAPK and the PI3K/Akt pathways. Cardiac-specific disruption of gp130 was shown to result in heart failure in response to mechano-stress accompanied by an increase in apoptosis of cardiac myocytes. Inactivation of STAT3 resulting from the loss of gp130 may be a key event in the transition from cardiac hypertrophy to heart failure. Proper vascular growth would be essential for normal cardiac development and the remodeling process. In addition to various factors, such as bcl-xL, inducible nitric oxide synthase and reactive oxygen species-scavenging proteins, VEGF has also been identified as a target gene of STAT3 and together can promote cardiac myocyte survival by preventing apoptosis and restoration of energy deprivation. In this regard, the gp130-receptor system and its main downstream mediator, STAT3, play a key role in the prevention of heart failure. In this review, current knowledge of the IL-6 family of cytokines relating to human cardiac disease is summarized, in addition to the potential role of gp130-mediated signaling systems in various models of experimental heart failure.

The extracellular matrix: at the center of it all

The extracellular matrix is not only a scaffold that provides support for cells, but it is also involved in cell-cell interactions, proliferation and migration. The intricate relationships among the cellular and acellular components of the heart drive proper heart development, homeostasis and recovery following pathological injury. Cardiac myocytes, fibroblasts and endothelial cells differentially express and respond to particular extracellular matrix factors that contribute to cell communication and overall cardiac function. In addition, turnover and synthesis of ECM components play an important role in cardiac function. Therefore, a better understanding of these factors and their regulation would lend insight into cardiac development and pathology, and would open doors to novel targeted pharmacologic therapies. This review highlights the importance of contributions of particular cardiac cell populations and extracellular matrix factors that are critical to the development and regulation of heart function.

Critical role for IL-6 in hypertrophy and fibrosis in chronic cardiac allograft rejection

Chronic cardiac allograft rejection is the major barrier to long term graft survival. There is currently no effective treatment for chronic rejection except re-transplantation. Though neointimal development, fibrosis, and progressive deterioration of graft function are hallmarks of chronic rejection, the immunologic mechanisms driving this process are poorly understood. These experiments tested a functional role for IL-6 in chronic rejection by utilizing serial echocardiography to assess the progression of chronic rejection in vascularized mouse cardiac allografts. Cardiac allografts in mice transiently depleted of CD4+ cells that develop chronic rejection were compared with those receiving anti-CD40L therapy that do not develop chronic rejection. Echocardiography revealed the development of hypertrophy in grafts undergoing chronic rejection. Histologic analysis confirmed hypertrophy that coincided with graft fibrosis and elevated intragraft expression of IL-6. To elucidate the role of IL-6 in chronic rejection, cardiac allograft recipients depleted of CD4+ cells were treated with neutralizing anti-IL-6 mAb. IL-6 neutralization ameliorated cardiomyocyte hypertrophy, graft fibrosis, and prevented deterioration of graft contractility associated with chronic rejection. These observations reveal a new paradigm in which IL-6 drives development of pathologic hypertrophy and fibrosis in chronic cardiac allograft rejection and suggest that IL-6 could be a therapeutic target to prevent this disease.

Percutaneous coronary interventions affect concentrations of interleukin 6 and its soluble receptors in coronary sinus blood in patients with stable angina

Coronary stenting may create local inflammatory reaction. Interleukin 6 effects depend on the presence of soluble receptors (sIL-6R and sgp130) that facilitate or impede interleukin 6 signal transduction. Concentrations of interleukin 6 and its soluble receptors were assessed in aorta and coronary sinus after stenting in optimally treated stable angina patients scheduled for elective stenting. Baseline levels of interleukin 6 and its soluble receptors in patients did not differ from healthy controls. Initial levels of sIL-6R in aorta were significantly higher than in coronary sinus but this difference disappeared after intervention. Stenting caused interleukin 6 concentration increase to a similar extent both in coronary sinus and in aorta. Moreover, there was significantly higher sgp130 concentration in coronary sinus than in aorta. Coronary intervention increases concentration of interleukin 6 in patients with stable angina. It affects the cardiac level of interleukin 6 soluble receptors what may influence the local inflammatory reaction.