In vivo TNF-alpha inhibition ameliorates cardiac mitochondrial dysfunction, oxidative stress, and apoptosis in experimental heart failure

Synbiotic supplementation ameliorates anxiety and myocardial ischaemia-reperfusion injury in hyperglycaemic rats by modulating gut microbiota

Hyperglycaemia, hyperlipidaemia, hypertension and obesity are the main risk factors affecting the development and prognosis of ischaemic heart disease, which is still an important cause of death today. In our study, male Sprague-Dawley rats were fed either a standard diet (SD) or a high fat and high carbohydrate diet (HF-HCD) for 8 weeks and streptozotocin (STZ) was injected at the seventh week of the feeding period. In one set of rats, a mixture of a prebiotic and probiotics (synbiotic, SYN) was administered by gavage starting from the beginning of the feeding period. Experimental myocardial ischaemia-reperfusion (30 min/60 min) was induced at the end of 8 weeks. Hyperglycaemia, hypertension and increased serum low-density lipoprotein levels occurred in SD- and HF-HCD-fed and STZ-treated rats followed for 8 weeks. Increased density of the Proteobacteria phylum was observed in rats with increased blood glucose levels, indicating intestinal dysbiosis. The severity of cardiac damage was highest in the dysbiotic HF-HCD-fed hyperglycaemic rats, which was evident with increased serum creatine kinase-MB (CK-MB), cardiac troponin I (cTnI), tumour necrosis factor-α, and interleukin-6 levels, along with a decrease in ST-segment resolution index. SYN supplementation to either a normal or a high-fat high-carbohydrate diet improved gut dysbiosis, reduced anxiety, decreased CK-MB and cTnI levels, and alleviated myocardial ischaemia-reperfusion injury in hyperglycaemic rats.

Cardiac dysfunction in sucrose-fed rats is associated with alterations of phospholamban phosphorylation and TNF-α levels

INTRODUCTION

High sucrose intake is linked to cardiovascular disease, a major global cause of mortality worldwide. Calcium mishandling and inflammation play crucial roles in cardiac disease pathophysiology.

OBJECTIVE

Evaluate if sucrose-induced obesity is related to deterioration of myocardial function due to alterations in the calcium-handling proteins in association with proinflammatory cytokines.

METHODS

Wistar rats were divided into control and sucrose groups. Over eight weeks, Sucrose group received 30% sucrose water. Cardiac function was determined in vivo using echocardiography and in vitro using papillary muscle assay. Western blotting was used to detect calcium handling protein; ELISA assay was used to assess TNF-α and IL-6 levels.

RESULTS

Sucrose led to cardiac dysfunction. RYR2, SERCA2, NCX, pPBL Ser16 and L-type calcium channels were unchanged. However, pPBL-Thr17, and TNF-α levels were elevated in the S group.

CONCLUSION

Sucrose induced cardiac dysfunction and decreased myocardial contractility in association with altered pPBL-Thr17 and elevated cardiac pro-inflammatory TNF-α.

Chronic TNF exposure induces glucocorticoid-like immunosuppression in the alveolar macrophages of aged mice that enhances their susceptibility to pneumonia

Chronic low-grade inflammation, particularly elevated tumor necrosis factor (TNF) levels, occurs due to advanced age and is associated with greater susceptibility to infection. One reason for this is age-dependent macrophage dysfunction (ADMD). Herein, we use the adoptive transfer of alveolar macrophages (AM) from aged mice into the airway of young mice to show that inherent age-related defects in AM were sufficient to increase the susceptibility to Streptococcus pneumoniae, a Gram-positive bacterium and the leading cause of community-acquired pneumonia. MAPK phosphorylation arrays using AM lysates from young and aged wild-type (WT) and TNF knockout (KO) mice revealed multilevel TNF-mediated suppression of kinase activity in aged mice. RNAseq analyses of AM validated the suppression of MAPK signaling as a consequence of TNF during aging. Two regulatory phosphatases that suppress MAPK signaling, Dusp1 and Ptprs, were confirmed to be upregulated with age and as a result of TNF exposure both ex vivo and in vitro. Dusp1 is known to be responsible for glucocorticoid-mediated immune suppression, and dexamethasone treatment increased Dusp1 and Ptprs expression in cells and recapitulated the ADMD phenotype. In young mice, treatment with dexamethasone increased the levels of Dusp1 and Ptprs and their susceptibility to infection. TNF-neutralizing antibody reduced Dusp1 and Ptprs levels in AM from aged mice and reduced pneumonia severity following bacterial challenge. We conclude that chronic exposure to TNF increases the expression of the glucocorticoid-associated MAPK signaling suppressors, Dusp1 and Ptprs, which inhibits AM activation and increases susceptibility to bacterial pneumonia in older adults.

Cardiac arrest, stony heart, and cardiopulmonary resuscitation: An updated revisit

The post-resuscitation period is recognized as the main predictor of cardiopulmonary resuscitation (CPR) outcomes. The first description of post-resuscitation syndrome and stony heart was published over 50 years ago. Major manifestations may include but are not limited to, persistent precipitating pathology, systemic ischemia/reperfusion response, post-cardiac arrest brain injury, and finally, post-cardiac arrest myocardial dysfunction (PAMD) after successful resuscitation. Why do some patients initially survive successful resuscitation, and others do not? Also, why does the myocardium response vary after resuscitation? These questions have kept scientists busy for several decades since the first successful resuscitation was described. By modifying the conventional modalities of resuscitation together with new promising agents, rescuers will be able to salvage the jeopardized post-resuscitation myocardium and prevent its progression to a dismal, stony heart. Community awareness and staff education are crucial for shortening the resuscitation time and improving short- and long-term outcomes. Awareness of these components before and early after the restoration of circulation will enhance the resuscitation outcomes. This review extensively addresses the underlying pathophysiology, management, and outcomes of post-resuscitation syndrome. The pattern, management, and outcome of PAMD and post-cardiac arrest shock are different based on many factors, including in-hospital cardiac arrest vs out-of-hospital cardiac arrest (OHCA), witnessed vs unwitnessed cardiac arrest, the underlying cause of arrest, the duration, and protocol used for CPR. Although restoring spontaneous circulation is a vital sign, it should not be the end of the game or lone primary outcome; it calls for better understanding and aggressive multi-disciplinary interventions and care. The development of stony heart post-CPR and OHCA remain the main challenges in emergency and critical care medicine.

Transcriptomic changes in glomeruli in response to a high salt challenge in the Dahl SS rat

Salt sensitivity impacts a significant portion of the population and is an important contributor to the development of chronic kidney disease. One of the significant early predictors of salt-induced damage is albuminuria, which reflects the deterioration of the renal filtration barrier: the glomerulus. Despite significant research efforts, there is still a gap in knowledge regarding the molecular mechanisms and signaling networks contributing to instigating and/or perpetuating salt-induced glomerular injury. To address this gap, we used 8-wk-old male Dahl salt-sensitive rats fed a normal-salt diet (0.4% NaCl) or challenged with a high-salt diet (4% NaCl) for 3 wk. At the end of the protocol, a pure fraction of renal glomeruli obtained by differential sieving was used for next-generation RNA sequencing and comprehensive semi-automatic transcriptomic data analyses, which revealed 149 differentially expressed genes (107 and 42 genes were downregulated and upregulated, respectively). Furthermore, a combination of predictive gene correlation networks and computational bioinformatic analyses revealed pathways impacted by a high salt dietary challenge, including renal metabolism, mitochondrial function, apoptotic signaling and fibrosis, cell cycle, inflammatory and immune responses, circadian clock, cytoskeletal organization, G protein-coupled receptor signaling, and calcium transport. In conclusion, we report here novel transcriptomic interactions and corresponding predicted pathways affecting glomeruli under salt-induced stress.NEW & NOTEWORTHY Our study demonstrated novel pathways affecting glomeruli under stress induced by dietary salt. Predictive gene correlation networks and bioinformatic semi-automatic analysis revealed changes in the pathways relevant to mitochondrial function, inflammatory, apoptotic/fibrotic processes, and cell calcium transport.

Harnessing the therapeutic potential of mesenchymal stem cell-derived exosomes in cardiac arrest: Current advances and future perspectives

BACKGROUND

Cardiac arrest (CA), characterized by sudden onset and high mortality rates, is one of the leading causes of death globally, with a survival rate of approximately 6-24%. Studies suggest that the restoration of spontaneous circulation (ROSC) hardly improved the mortality rate and prognosis of patients diagnosed with CA, largely due to ischemia-reperfusion injury.

MAIN BODY

Mesenchymal stem cells (MSCs) exhibit self-renewal and strong potential for multilineage differentiation. Their effects are largely mediated by extracellular vesicles (EVs). Exosomes are the most extensively studied subgroup of EVs. EVs mainly mediate intercellular communication by transferring vesicular proteins, lipids, nucleic acids, and other substances to regulate multiple processes, such as cytokine production, cell proliferation, apoptosis, and metabolism. Thus, exosomes exhibit significant potential for therapeutic application in wound repair, tissue reconstruction, inflammatory reaction, and ischemic diseases.

CONCLUSION

Based on similar pathological mechanisms underlying post-cardiac arrest syndrome involving various tissues and organs in many diseases, the review summarizes the therapeutic effects of MSC-derived exosomes and explores the prospects for their application in the treatment of CA.

FAM3A Ameliorates Brain Impairment Induced by Hypoxia-Ischemia in Neonatal Rat

Hypoxia-ischemia (HI) during crucial periods of brain formation can lead to changes in brain morphology, propagation of neuronal stimuli, and permanent neurodevelopmental impairment, which can have profound effects on cognitive function later in life. FAM3A, a subgroup of family with sequence similarity 3 (FAM3) gene family, is ubiquitously expressed in almost all cells. Overexpression of FAM3A has been evidenced to reduce hyperglycemia via the PI3K/Akt signaling pathway and protect mitochondrial function in neuronal HT22 cells. This study aims to evaluate the protective role of FAM3A in HI-induced brain impairment. Experimentally, maternal rats underwent uterine artery bilateral ligation to induce neonatal HI on day 14 of gestation. At 6 weeks of age, cognitive development assessments including NSS, wire grip, and water maze were carried out. The animals were then sacrificed to assess cerebral mitochondrial function as well as levels of FAM3A, TNF-α and IFN-γ. Results suggest that HI significantly reduced FAM3A expression in rat brain tissues, and that overexpression of FAM3A through lentiviral transduction effectively improved cognitive and motor functions in HI rats as reflected by improved NSS evaluation, cerebral water content, limb strength, as well as spatial learning and memory. At the molecular level, overexpression of FAM3A was able to promote ATP production, balance mitochondrial membrane potential, and reduce levels of pro-inflammatory cytokines TNF-α and IFN-γ. We conclude that FAM3A overexpression may have a protective effect on neuron morphology, cerebral mitochondrial as well as cognitive function. Created with Biorender.com.

Tumor Necrosis Factor-α-Induced C-C Motif Chemokine Ligand 20 Expression through TNF Receptor 1-Dependent Activation of EGFR/p38 MAPK and JNK1/2/FoxO1 or the NF-κB Pathway in Human Cardiac Fibroblasts

Tumor necrosis factor (TNF)-α is involved in the pathogenesis of cardiac injury, inflammation, and apoptosis. It is a crucial pro-inflammatory cytokine in many heart disorders, including chronic heart failure and ischemic heart disease, contributing to cardiac remodeling and dysfunction. The implication of TNF-α in inflammatory responses in the heart has been indicated to be mediated through the induction of C-C Motif Chemokine Ligand 20 (CCL20). However, the detailed mechanisms of TNF-α-induced CCL20 upregulation in human cardiac fibroblasts (HCFs) are not completely defined. We demonstrated that in HCFs, TNF-α induced CCL20 mRNA expression and promoter activity leading to an increase in the secretion of CCL20. TNF-α-mediated responses were attenuated by pretreatment with TNFR1 antibody, the inhibitor of epidermal growth factor receptor (EGFR) (AG1478), p38 mitogen-activated protein kinase (MAPK) (p38 inhibitor VIII, p38i VIII), c-Jun amino N-terminal kinase (JNK)1/2 (SP600125), nuclear factor kappaB (NF-κB) (helenalin), or forkhead box O (FoxO)1 (AS1841856) and transfection with siRNA of TNFR1, EGFR, p38α, JNK2, p65, or FoxO1. Moreover, TNF-α markedly induced EGFR, p38 MAPK, JNK1/2, FoxO1, and NF-κB p65 phosphorylation which was inhibited by their respective inhibitors in these cells. In addition, TNF-α-enhanced binding of FoxO1 or p65 to the CCL20 promoter was inhibited by p38i VIII, SP600125, and AS1841856, or helenalin, respectively. Accordingly, in HCFs, our findings are the first to clarify that TNF-α-induced CCL20 secretion is mediated through a TNFR1-dependent EGFR/p38 MAPK and JNK1/2/FoxO1 or NF-κB cascade. We demonstrated that TNFR1-derived EGFR transactivation is involved in the TNF-α-induced responses in these cells. Understanding the regulation of CCL20 expression by TNF-α on HCFs may provide a potential therapeutic strategy in cardiac inflammatory disorders.

Mitochondria-Targeted, Nanoparticle-Based Drug-Delivery Systems: Therapeutics for Mitochondrial Disorders

Apart from ATP generation, mitochondria are involved in a wide range of functions, making them one of the most prominent organelles of the human cell. Mitochondrial dysfunction is involved in the pathophysiology of several diseases, such as cancer, neurodegenerative diseases, cardiovascular diseases, and metabolic disorders. This makes it a target for a variety of therapeutics for the diagnosis and treatment of these diseases. The use of nanoparticles to target mitochondria has significant importance in modern times because they provide promising ways to deliver drug payloads to the mitochondria by overcoming challenges, such as low solubility and poor bioavailability, and also resolve the issues of the poor biodistribution of drugs and pharmacokinetics with increased specificity. This review assesses nanoparticle-based drug-delivery systems, such as liposomes, DQAsome, MITO-Porters, micelles, polymeric and metal nanocarriers, as well as quantum dots, as mitochondria-targeted strategies and discusses them as a treatment for mitochondrial disorders.

Rosuvastatin Alleviates Coronary Microembolization-Induced Cardiac Injury by Suppressing Nox2-Induced ROS Overproduction and Myocardial Apoptosis

To explore the mechanism by which rosuvastatin prevents coronary microembolism (CME)-induced cardiac injury and cardiomyocyte apoptosis. Animal and cell models of CME were established and treated with different doses of rosuvastatin. Echocardiography and histological staining were applied to assess left ventricular function and cardiac injury. Masson trichrome staining was used to evaluate fibrin deposition in the myocardium. The activity of lactate dehydrogenase (LDH) in serum and cell culture supernatant was detected. TUNEL staining and flow cytometry were used to evaluate apoptosis in myocardium and cardiomyocytes, respectively. The activity of ROS was revealed by DHE staining. The expression levels of Nox2, cleaved caspase-3, cytochrome C, p53, Bax and Bcl-2 were also detected. Rosuvastatin pretreatment improved the left ventricular function of CME mice and reduced inflammatory cell infiltration and fibrin deposition in the myocardium. Rosuvastatin reduced the production of ROS by inhibiting the expression of Nox2. Rosuvastatin also downregulated pro-apoptotic proteins cleaved caspase-3, cytochrome C, p53 and Bax, and upregulated anti-apoptotic Bcl-2. Rosuvastatin mitigates CME-induced cardiac injury by inhibiting Nox2-induced ROS overproduction and alleviating p53/Bax/Bcl-2-dependent cardiomyocyte apoptosis.

Role of circulating molecules in age-related cardiovascular and metabolic disorders

Studies analyzing heterochronic parabiosis mice models showed that molecules in the blood of young mice rejuvenate aged mice. Therefore, blood-based therapies have become one of the therapeutic approaches to be considered for age-related diseases. Blood includes numerous biologically active molecules such as proteins, metabolites, hormones, miRNAs, etc. and accumulating evidence indicates some of these change their concentration with chronological aging or age-related disorders. The level of some circulating molecules showed a negative or positive correlation with all-cause mortality, cardiovascular events, or metabolic disorders. Through analyses of clinical/translation/basic research, some molecules were focused on as therapeutic targets. One approach is the supplementation of circulating anti-aging molecules. Favorable results in preclinical studies let some molecules to be tested in humans. These showed beneficial or neutral results, and some were inconsistent. Studies with rodents and humans indicate circulating molecules can be recognized as biomarkers or therapeutic targets mediating their pro-aging or anti-aging effects. Characterization of these molecules with aging, testing their biological effects, and finding mimetics of young systemic milieu continue to be an interesting and important research topic to be explored.

ADAM17, A Key Player of Cardiac Inflammation and Fibrosis in Heart Failure Development During Chronic Catecholamine Stress

Heart failure development is characterized by persistent inflammation and progressive fibrosis owing to chronic catecholamine stress. In a chronic stress state, elevated catecholamines result in the overstimulation of beta-adrenergic receptors (βARs), specifically β2-AR coupling with Gαi protein. Gαi signaling increases the activation of receptor-stimulated p38 mitogen-activated-protein-kinases (p38 MAPKs) and extracellular signal-regulated kinases (ERKs). Phosphorylation by these kinases is a common way to positively regulate the catalytic activity of A Disintegrin and Metalloprotease 17 (ADAM17), a metalloprotease that has grown much attention in recent years and has emerged as a chief regulatory hub in inflammation, fibrosis, and immunity due to its vital proteolytic activity. ADAM17 cleaves and activates proinflammatory cytokines and fibrotic factors that enhance cardiac dysfunction via inflammation and fibrosis. However, there is limited information on the cardiovascular aspect of ADAM17, especially in heart failure. Hence, this concise review provides a comprehensive insight into the structure of ADAM17, how it is activated and regulated during chronic catecholamine stress in heart failure development. This review highlights the inflammatory and fibrotic roles of ADAM17’s substrates; Tumor Necrosis Factor α (TNFα), soluble interleukin-6 receptor (sIL-6R), and amphiregulin (AREG). Finally, how ADAM17-induced chronic inflammation and progressive fibrosis aggravate cardiac dysfunction is discussed.

Targeting Mediators of Inflammation in Heart Failure: A Short Synthesis of Experimental and Clinical Results

Inflammation has emerged as an important contributor to heart failure (HF) development and progression. Current research data highlight the diversity of immune cells, proteins, and signaling pathways involved in the pathogenesis and perpetuation of heart failure. Chronic inflammation is a major cardiovascular risk factor. Proinflammatory signaling molecules in HF initiate vicious cycles altering mitochondrial function and perturbing calcium homeostasis, therefore affecting myocardial contractility. Specific anti-inflammatory treatment represents a novel approach to prevent and slow HF progression. This review provides an update on the putative roles of inflammatory mediators involved in heart failure (tumor necrosis factor-alpha; interleukin 1, 6, 17, 18, 33) and currently available biological and non-biological therapy options targeting the aforementioned mediators and signaling pathways. We also highlight new treatment approaches based on the latest clinical and experimental research.

Exosomes derived from miR-129-5p modified bone marrow mesenchymal stem cells represses ventricular remolding of mice with myocardial infarction

Myocardial infraction (MI) is a severe disease with great mortality. Mesenchymal stem cells-derived exosomes display protection against MI. MicroRNA-129-5p was reported to exert anti-inflammation activity by targeting high mobility group box 1 (HMGB1). In the present study, the effects of MSCs derived exosomes overexpressing miR-129-5p on MI were evaluated. Bone marrow mesenchymal stem cells (BMSCs) were transfected with miR-129-5p for exosomes isolation. Myocardial infraction mice model was established and administrated exosomes overexpressing miR-129-5p. The cardiac function, expression of HMGB1, inflammatory cytokines, apoptosis and fibrosis in heart tissues were measured. miR-129-5p inhibited HMGB1 expression in BMSCs. Myocardial infraction mice treated with exosomes overexpressing miR-129-5p had enhanced cardiac function and decreased expression of HMGB1 and production of inflammatory cytokines. Exosomes overexpressing miR-129-5p further prevented apoptosis and fibrosis. Exosome-mediated transfer of miR-129-5p suppressed inflammation in MI mice by targeting HMGB1.

Dilated Cardiomyopathy due to the Novel MT-CYB Missense Mutation m.14757T>C

Mitochondrial DNA (mtDNA) mutations frequently manifest with multisystem disease, including cardiomyopathy (CM). Various studies described mutations in protein-encoding mtDNA genes, such as cytochrome-b, manifesting with CM. A detailed clinical, biochemical, and molecular genetic analysis was performed in a 40-year-old male with dilated CM (DCM) to detect the underlying mtDNA defect. Muscle biopsy showed complex-III deficiency, and sequencing of the cytochrome-b gene revealed the pathogenic variant m.14757T>C in MT-CYB, resulting in the replacement of the hydrophobic methionine by the polar threonine (M4T). By application of the PolyPhen algorithm the variant was predicted as pathogenic. The mutation was not found in 100 healthy controls and never reported as a neutral polymorphism despite extensive sequencing of the cytochrome-b gene in 2,704 normal healthy controls from different ethnic backgrounds. In conclusion, the novel variant m.14757T>C in MT-CYB is associated with DCM suggesting a pathophysiologic role of the variant in the development of DCM.

Inflammation in Human Heart Failure: Major Mediators and Therapeutic Targets

Inflammation has been recognized as a major pathophysiological contributor to the entire spectrum of human heart failure (HF), including HF with reduced ejection fraction, HF with preserved ejection fraction, acute HF and cardiogenic shock. Nevertheless, the results of several trials attempting anti-inflammatory strategies in HF patients have not been consistent or motivating and the clinical implementation of anti-inflammatory treatments for HF still requires larger and longer trials, as well as novel and/or more specific drugs. The present work reviews the different inflammatory mechanisms contributing to each type of HF, the major inflammatory mediators involved, namely tumor necrosis factor alpha, the interleukins 1, 6, 8, 10, 18, and 33, C-reactive protein and the enzymes myeloperoxidase and inducible nitric oxide synthase, and their effects on heart function. Furthermore, several trials targeting these mediators or involving other anti-inflammatory treatments in human HF are also described and analyzed. Future therapeutic advances will likely involve tailored anti-inflammatory treatments according to the patient's inflammatory profile, as well as the development of resolution pharmacology aimed at stimulating resolution of inflammation pathways in HF.

The role of tumor necrosis factor in triggering activation of natural killer cell, multi-organ mitochondrial dysfunction and hypertension during pregnancy

Pre-eclampsia (PE) is a hypertensive disorder of pregnancy associated with chronic inflammation, mitochondrial (mt) dysfunction and fetal demise. Natural Killer cells (NK cells) are critical for the innate immune response against tumors or infection by disrupting cellular mt function and causing cell death. Although NK cells can be stimulated by Tumor necrosis factor alpha (TNF-α), we don't know the role of TNF-α on NK cell mediated mt dysfunction during PE. Our objective was to determine if mechanisms of TNF-α induced hypertension included activation of NK cells and multi-organ mt dysfunction during pregnancy. Pregnant rats were divided into 2 groups: normal pregnant (NP) (n = 18) and NP + TNF-α (n = 18). On gestational day 14, TNF-α (50 ng/ml) was infused via mini-osmotic pump and on day 18, carotid artery catheters were inserted. Blood pressure (MAP) and samples were collected on day 19. TNF-α increased MAP (109 ± 2 vs 100 ± 2, p < 0.05), circulating cytolytic NK cells (0.771 ± 0.328 vs.0.008 ± 0.003% gated, <0.05) and fetal reabsorptions compared to NP rats. Moreover, TNF-α caused mtROS in the placenta (12976 ± 7038 vs 176.9 ± 68.04% fold, p < 0.05) and in the kidney (2191 ± 1027 vs 816 ± 454.7% fold, p < 0.05) compared to NP rats. TNF-α induced hypertension is associated fetal demise, activation of NK cells and multi-organ mt dysfunction which could be mechanisms for fetal demise and hypertension. Understanding of the mechanisms by which TNF-α causes pathology is important for the use of anti-TNF-α therapeutic agents in pregnancies complicated by PE.

Cytokines as therapeutic targets for cardio- and cerebrovascular diseases

Despite major advances in prevention and treatment, cardiac and cerebral atherothrombotic complications still account for substantial morbidity and mortality worldwide. In this context, inflammation is involved in the chronic process leading atherosclerotic plaque formation and its complications, as well as in the maladaptive response to acute ischemic events. For this reason, modulation of inflammation is nowadays seen as a promising therapeutic strategy to counteract the burden of cardio- and cerebrovascular disease. Being produced and recognized by both inflammatory and vascular cells, the complex network of cytokines holds key functions in the crosstalk of these two systems and orchestrates the progression of atherothrombosis. By binding to membrane receptors, these soluble mediators trigger specific intracellular signaling pathways eventually leading to the activation of transcription factors and a deep modulation of cell function. Both stimulatory and inhibitory cytokines have been described and progressively reported as markers of disease or interesting therapeutic targets in the cardiovascular field. Nevertheless, cytokine inhibition is burdened by harmful side effects that will most likely prevent its chronic use in favor of acute administrations in well-selected subjects at high risk. Here, we summarize the current state of knowledge regarding the modulatory role of cytokines on atherosclerosis, myocardial infarction, and stroke. Then, we discuss evidence from clinical trials specifically targeting cytokines and the potential implication of these advances into daily clinical practice.

Epigenetic Regulation of Pulmonary Arterial Hypertension-Induced Vascular and Right Ventricular Remodeling: New Opportunities?

Pulmonary artery hypertension (PAH) is a rare chronic disease with high impact on patients’ quality of life and currently no available cure. PAH is characterized by constant remodeling of the pulmonary artery by increased proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs), fibroblasts (FBs) and endothelial cells (ECs). This remodeling eventually leads to increased pressure in the right ventricle (RV) and subsequent right ventricle hypertrophy (RVH) which, when left untreated, progresses into right ventricle failure (RVF). PAH can not only originate from heritable mutations, but also develop as a consequence of congenital heart disease, exposure to drugs or toxins, HIV, connective tissue disease or be idiopathic. While much attention was drawn into investigating and developing therapies related to the most well understood signaling pathways in PAH, in the last decade, a shift towards understanding the epigenetic mechanisms driving the disease occurred. In this review, we reflect on the different epigenetic regulatory factors that are associated with the pathology of RV remodeling, and on their relevance towards a better understanding of the disease and subsequently, the development of new and more efficient therapeutic strategies.

Targeted anti-inflammatory therapy is a new insight for reducing cardiovascular events: A review from physiology to the clinic

Despite considerable progressions, cardiovascular disease (CVD) is still one of the major causes of mortality around the world, indicates an important and unmet clinical need. Recently, extensive studies have been performed on the role of inflammatory factors as either a major or surrogate factor in the pathophysiology of CVD. Epidemiological observations suggest the theory of the role of inflammatory mediators in the development of cardiovascular events. This may support the idea that targeted anti-inflammatory therapies, on the background of traditional validated medical therapies, can play a significant role in prevention and even reduction of cardiovascular disorders. Many randomized controlled trials have shown that drugs commonly useful for primary and secondary prevention of CVD have an anti-inflammatory mechanism. Further, many anti-inflammatory drugs are being examined because of their potential to reduce the risk of cardiovascular problems. In this study, we review the process of inflammation in the development of cardiovascular events, both in vivo and clinical evidence in immunotherapy for CVD.

The roles of resveratrol on cardiac mitochondrial function in cardiac diseases

Left ventricular (LV) dysfunction is commonly associated with a variety of health conditions including acute myocardial infarction and obesity/diabetes. In addition, administration of several pharmacological agents such as anticancer, antiviral, and immunosuppressive drugs has been shown to be related with LV dysfunction. The molecular mechanism responsible for LV dysfunction has been extensively studied, and it has been proposed that the overproduction of reactive oxygen species (ROS) plays a crucial role in the regulation of this function. Mitochondria require the balance between ROS production and antioxidants to maintain their appropriate function and to prevent excessive ROS production. Thus, the excessive production of ROS and the reduced scavenging process under any pathological conditions could disrupt mitochondrial function, leading to energy depletion with subsequent cell death. Therefore, maintenance of the balance between oxidative stress and antioxidants is essential. Resveratrol, a stilbene, has been investigated extensively, and potentially used to treat or prevent various cardiovascular diseases. Resveratrol directly upregulates antioxidative capacity by increasing antioxidant genes such as heme oxygenase-1, superoxide dismutase, catalase, and glutathione. In this review, accumulated data from in vitro, ex vivo, and in vivo studies regarding the effects of resveratrol on cardiac mitochondrial function in cardiac pathologies are comprehensively summarized and discussed. Since there is no conclusive available clinical study regarding the effects of resveratrol on cardiac mitochondrial function, this review also aims to encourage more clinical investigations to confirm findings from basic research. This comprehensive review will provide insight regarding the potential mechanistic roles of resveratrol in preventing and/or treating patients with cardiovascular diseases to improve LV function and their health status.

The Role of Mitochondria in Inflammation: From Cancer to Neurodegenerative Disorders

The main features that are commonly attributed to mitochondria consist of the regulation of cell proliferation, ATP generation, cell death and metabolism. However, recent scientific advances reveal that the intrinsic dynamicity of the mitochondrial compartment also plays a central role in proinflammatory signaling, identifying these organelles as a central platform for the control of innate immunity and the inflammatory response. Thus, mitochondrial dysfunctions have been related to severe chronic inflammatory disorders. Strategies aimed at reestablishing normal mitochondrial physiology could represent both preventive and therapeutic interventions for various pathologies related to exacerbated inflammation. Here, we explore the current understanding of the intricate interplay between mitochondria and the innate immune response in specific inflammatory diseases, such as neurological disorders and cancer.

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.

Chlorogenic acid: A potent molecule that protects cardiomyocytes from TNF-α-induced injury via inhibiting NF-κB and JNK signals

The traditional Chinese herb Lonicerae Japonicae Flos has shown significant clinical benefits in the treatment of heart failure, but the mechanism remains unclear. As the main active ingredient found in the plasma after oral administration of Lonicerae Japonicae Flos, chlorogenic acid (CGA) has been reported to possess anti‐inflammatory, anti‐oxidant and anti‐apoptosis function. We firstly confirmed the cardioprotective effects of CGA in transverse aortic constriction (TAC)‐induced heart failure mouse model, through mitigating the TNF‐α–induced toxicity. We further used TNF‐α‐induced cardiac injury in human induced pluripotent stem cell‐derived cardiomyocytes (hiPSC‐CMs) to elucidate the underlying mechanisms. CGA pre‐treatment could reverse TNF‐α–induced cellular injuries, including improved cell viability, increased mitochondrial membrane potential and inhibited cardiomyocytes apoptosis. We then examined the NF‐κB/p65 and major mitogen‐activated protein kinases (MAPKs) signalling pathways involved in TNF‐α–induced apoptosis of hiPSC‐CMs. Importantly, CGA can directly inhibit NF‐κB signal by suppressing the phosphorylation of NF‐κB/p65. As for the MAPKs, CGA suppressed the activity of only c‐Jun N‐terminal kinase (JNK), but enhanced extracellular signal‐regulated kinase1/2 (ERK1/2) and had no effect on p38. In summary, our study revealed that CGA has profound cardioprotective effects through inhibiting the activation of NF‐κB and JNK pathway, providing a novel therapeutic alternative for prevention and treatment of heart failure.

Redefining biomarkers in heart failure

Heart failure (HF) is the end result of many different cardiac and non-cardiac abnormalities leading to a complex clinical entity. In this view, the use of biomarkers in HF should be deeply reconsidered; indeed, the same biomarker may carry a different significance in patients with preserved or reduced EF. The aim of this review is to reconsider the role of biomarkers in HF, based on the different clinical characteristics of this syndrome. The role of cardiac and non-cardiac biomarkers will be reviewed with respect of the different clinical manifestations of this syndrome.

Role of cardiac inflammation in right ventricular failure

Right ventricular failure (RVF) is the main determinant of mortality in patients with pulmonary arterial hypertension (PAH). Although the exact pathophysiology underlying RVF remains unclear, inflammation may play an important role, as it does in left heart failure. Perivascular pulmonary artery and systemic inflammation is relatively well studied and known to contribute to the initiation and maintenance of the pulmonary vascular insult in PAH. However, less attention has been paid to the role of cardiac inflammation in RVF and PAH. Consistent with many other types of heart failure, cardiac inflammation, triggered by systemic and local stressors, has been shown in RVF patients as well as in RVF animal models. RV inflammation likely contributes to impaired RV contractility, maladaptive remodelling and a vicious circle between RV and pulmonary vascular injury. Although the potential to improve RV function through anti-inflammatory therapy has not been tested, this approach has been applied clinically in left ventricular failure patients, with variable success. Because inflammation plays a dual role in the development of both pulmonary vascular pathology and RVF, anti-inflammatory therapies may have a potential double benefit in patients with PAH and associated RVF.

NF-κB-mediated metabolic remodelling in the inflamed heart in acute viral myocarditis

Acute viral myocarditis (VM), characterised by leukocyte infiltration and dysfunction of the heart, is an important cause of sudden cardiac death in young adults. Unfortunately, to date, the pathological mechanisms underlying cardiac failure in VM remain incompletely understood. In the current study, we investigated if acute VM leads to cardiac metabolic rewiring and if this process is driven by local inflammation. Transcriptomic analysis of cardiac biopsies from myocarditis patients and a mouse model of VM revealed prominent reductions in the expression of a multitude of genes involved in mitochondrial oxidative energy metabolism. In mice, this coincided with reductions in high-energy phosphate and NAD levels, as determined by Imaging Mass Spectrometry, as well as marked decreases in the activity, protein abundance and mRNA levels of various enzymes and key regulators of cardiac oxidative metabolism. Indicative of fulminant cardiac inflammation, NF-κB signalling and inflammatory cytokine expression were potently induced in the heart during human and mouse VM. In cultured cardiomyocytes, cytokine-mediated NF-κB activation impaired cardiomyocyte oxidative gene expression, likely by interfering with the PGC-1 (peroxisome proliferator-activated receptor (PPAR)-γ co-activator) signalling network, the key regulatory pathway controlling cardiomyocyte oxidative metabolism. In conclusion, we provide evidence that acute VM is associated with extensive cardiac metabolic remodelling and our data support a mechanism whereby cytokines secreted primarily from infiltrating leukocytes activate NF-κB signalling in cardiomyocytes thereby inhibiting the transcriptional activity of the PGC-1 network and consequently modulating myocardial energy metabolism.

Skeletal muscle bioenergetics in aging and heart failure

Changes in mitochondrial capacity and quality play a critical role in skeletal and cardiac muscle dysfunction. In vivo measurements of mitochondrial capacity provide a clear link between physical activity and mitochondrial function in aging and heart failure, although the cause and effect relationship remains unclear. Age-related decline in mitochondrial quality leads to mitochondrial defects that affect redox, calcium, and energy-sensitive signaling by altering the cellular environment that can result in skeletal muscle dysfunction independent of reduced mitochondrial capacity. This reduced mitochondrial quality with age is also likely to sensitize skeletal muscle mitochondria to elevated angiotensin or beta-adrenergic signaling associated with heart failure. This synergy between aging and heart failure could further disrupt cell energy and redox homeostasis and contribute to exercise intolerance in this patient population. Therefore, the interaction between aging and heart failure, particularly with respect to mitochondrial dysfunction, should be a consideration when developing strategies to improve quality of life in heart failure patients. Given the central role of the mitochondria in skeletal and cardiac muscle dysfunction, mitochondrial quality may provide a common link for targeted interventions in these populations.

Translational overview of cytokine inhibition in acute myocardial infarction and chronic heart failure

Many cytokines are currently under investigation as potential target to improve cardiac function and outcome in the setting of acute myocardial infarction (MI) or chronic heart failure (HF). Here we aim to provide a translational overview of cytokine inhibiting therapies tested in experimental models and clinical studies. In various experimental studies, inhibition of interleukin-1 (IL-1), -6 (IL-6), -8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), CC- and CXC chemokines, and tumor necrosis factor-α (TNF-α) had beneficial effects on cardiac function and outcome. On the other hand, neutral or even detrimental results have been reported for some (IL-1, IL-6, IL-8, and MCP-1). Ambivalence of cytokine function, differences in study designs, treatment regimens and chosen endpoints hamper the translation of experimental research into clinical practice. Human studies are currently limited to IL-1β inhibition, IL-1 receptor antagonists (IL-1RA), IL-6 receptor antagonists (IL-6RA) or TNF inhibition. Despite favorable effects on cardiovascular events observed in retrospective cohort studies of rheumatoid arthritis patients treated with TNF inhibition or IL-1RA, most prospective studies reported disappointing and inconsistent results. Smaller studies (n < 100) generally reported favorable results of anticytokine therapy on cardiac function, but only one of the larger studies (n > 100) evaluating IL-1β inhibition presented positive results on outcome. In conclusion, of the 10 anticytokine therapies tested in animals models beneficial effects have been reported in at least one setting. In larger clinical studies, findings were unsatisfactory in all but one. Many anticytokine therapies with promising animal experimental data continue to require further evaluation in humans.

Unmet Needs in the Pathogenesis and Treatment of Cardiovascular Comorbidities in Chronic Inflammatory Diseases

The developments that have taken place in recent decades in the diagnosis and therapy of a number of diseases have led to improvements in prognosis and life expectancy. As a consequence, there has been an increase in the number of patients affected by chronic diseases and who can face new pathologies during their lifetime. The prevalence of chronic heart failure, for example, is approximately 1-2% of the adult population in developed countries, rising to ≥10% among people >70 years of age; in 2015, more than 85 million people in Europe were living with some sort of cardiovascular disease (CVD) (Lubrano and Balzan World J Exp Med 5:21-32, 5; Takahashi et al. Circ J 72:867-72, 8; Kaptoge et al. Lancet 375:132-40, 9). Chronic disease can become, in turn, a major risk factor for other diseases. Furthermore, several new drugs have entered clinical practice whose adverse effects on multiple organs are still to be evaluated. All this necessarily involves a multidisciplinary vision of medicine, where the physician must view the patient as a whole and where collaboration between the various specialists plays a key role. An example of what has been said so far is the relationship between CVD and chronic inflammatory diseases (CIDs). Patients with chronic CVD may develop a CID within their lifetime, and, vice versa, a CID can be a risk factor for the development of CVD. Moreover, drugs used for the treatment of CIDs may have side effects involving the cardiovascular system and thus may be contraindicated. The purpose of this paper is to investigate the close relationship between these two groups of diseases and to provide recommendations on the diagnostic approach and treatments in light of the most recent scientific data available.

SOCS-1 is involved in TNF-α-induced mitochondrial dysfunction and apoptosis in renal tubular epithelial cells

Tumor necrosis factor-α (TNF-α) is suggested to induce mitochondrial dysfunction and apoptosis of renal tubular epithelial cells that possibly exacerbates renal function in chronic kidney disease (CKD). Here we investigated whether suppressor of cytokine signaling-1 (SOCS-1), an inhibitor of cytokine signaling, was involved in TNF-α-induced human renal tubular epithelial cells (HKCs) oxidative stress and apoptosis. TNF-α promoted the protein and mRNA expression of SOCS-1 in a time and dose dependent manner, along with increased cell apoptosis and activation of apoptosis signal regulating kinase-1(ASK1) in HKCs. Furthermore, overexpression of SOCS-1 in HKCs reduced TNF-α-mediated oxidative stress and apoptosis. Meanwhile, We also found that overexpression of SOCS-1 could regulate the activity of JAK/STAT signaling pathway. In addition, a specific JAK2 inhibitor, AG490, that both attenuated TNF-α-induced oxidative stress, also reduced apoptosis. Taken together, overexpression of SOCS-1 prevented TNF-α-mediated cell oxidative stress and apoptosis may be via suppression of JAK/STAT signaling pathway activation in HKCs.

Inflammation and mitochondrial dysfunction: A vicious circle in neurodegenerative disorders?

Experimental evidence supports an intricate association between inflammation and mitochondrial dysfunction as main contributors of neurological diseases. Inflammatory mediators produced by activated microglia and infiltrated immune cells trigger intracellular signalling cascades that can alter cellular mitochondrial metabolism. Cytokines, particularly tumor necrosis factor-alpha, impede mitochondrial oxidative phosphorylation and associated ATP production and instigate mitochondrial reactive oxygen species production. This culminates in mitochondrial membrane permeabilization, altered mitochondrial dynamics and might ultimately result in cell death. When severely injured mitochondria are not appropriately removed by mitophagy they can release their contents into the cytosol and extracellular environment and thereby amplify the inflammatory process. Here we provide a comprehensive overview on how inflammatory mediators impair mitochondrial metabolism and discuss how defective mitochondria can elicit and potentiate an inflammatory response.

Metabolic remodeling in hypertrophied and failing myocardium: a review

The energy starvation hypothesis proposes that maladaptive metabolic remodeling antedates, initiates, and maintains adverse contractile dysfunction in heart failure (HF). Better understanding of the cardiac metabolic phenotype and metabolic signaling could help identify the role metabolic remodeling plays within HF and the conditions known to transition toward HF, including "pathological" hypertrophy. In this review, we discuss metabolic phenotype and metabolic signaling in the contexts of pathological hypertrophy and HF. We discuss the significance of alterations in energy supply (substrate utilization, oxidative capacity, and phosphotransfer) and energy sensing using observations from human and animal disease models and models of manipulated energy supply/sensing. We aim to provide ways of thinking about metabolic remodeling that center around metabolic flexibility, capacity (reserve), and efficiency rather than around particular substrate preferences or transcriptomic profiles. We show that maladaptive metabolic remodeling takes multiple forms across multiple energy-handling domains. We suggest that lack of metabolic flexibility and reserve (substrate, oxidative, and phosphotransfer) represents a final common denominator ultimately compromising efficiency and contractile reserve in stressful contexts.

TNFR2 Stimulation Promotes Mitochondrial Fusion via Stat3- and NF-kB-Dependent Activation of OPA1 Expression

Supplemental Digital Content is available in the text.

Rationale:

Mitochondria are important cellular organelles and play essential roles in maintaining cell structure and function. Emerging evidence indicates that in addition to having proinflammatory and proapoptotic effects, TNFα (tumor necrosis factor α) can, under certain circumstances, promote improvements in mitochondrial integrity and function, phenomena that can be ascribed to the existence of TNFR2 (TNFα receptor 2).

Objective:

The present study aimed to investigate whether and how TNFR2 activation mediates the effects of TNFα on mitochondria.

Methods and Results:

Freshly isolated neonatal mouse cardiac myocytes treated with shRNA targeting TNFR1 were used to study the effects of TNFR2 activation on mitochondrial function. Neonatal mouse cardiac myocytes exhibited increases in mitochondrial fusion, a change that was associated with increases in mitochondrial membrane potential, intracellular ATP levels, and oxygen consumption capacity. Importantly, TNFR2 activation–induced increases in OPA1 (optic atrophy 1) protein expression were responsible for the above enhancements, and these changes could be attenuated using siRNA targeting OPA1. Moreover, both Stat3 and RelA bound to the promoter region of OPA1 and their interactions synergistically upregulated OPA1 expression at the transcriptional level. Stat3 acetylation at lysine 370 or lysine 383 played a key role in the ability of Stat3 to form a supercomplex with RelA. Meanwhile, p300 modulated Stat3 acetylation in HEK293T (human embryonic kidney 293T) cells, and p300-mediated Stat3/RelA interactions played an indispensable role in OPA1 upregulation. Finally, TNFR2 activation exerted beneficial effects on OPA1 expression in an in vivo transverse aortic constriction model, whereby TNFR1-knockout mice exhibited better outcomes than in mice with both TNFR1 and TNFR2 knocked out.

Conclusions:

TNFR2 activation protects cardiac myocytes against stress by upregulating OPA1 expression. This process was facilitated by p300-mediated Stat3 acetylation and Stat3/RelA interactions, leading to improvements in mitochondrial morphology and function.

TNFα Modulates Cardiac Conduction by Altering Electrical Coupling between Myocytes

Background: Tumor Necrosis Factor α (TNFα) upregulation during acute inflammatory response has been associated with numerous cardiac effects including modulating Connexin43 and vascular permeability. This may in turn alter cardiac gap junctional (GJ) coupling and extracellular volume (ephaptic coupling) respectively. We hypothesized that acute exposure to pathophysiological TNFα levels can modulate conduction velocity (CV) in the heart by altering electrical coupling: GJ and ephaptic.

Methods and Results: Hearts were optically mapped to determine CV from control, TNFα and TNFα + high calcium (2.5 vs. 1.25 mM) treated guinea pig hearts over 90 mins. Transmission electron microscopy was performed to measure changes in intercellular separation in the gap junction-adjacent extracellular nanodomain—perinexus (W_P). Cx43 expression and phosphorylation were determined by Western blotting and Cx43 distribution by confocal immunofluorescence. At 90 mins, longitudinal and transverse CV (CV_L and CV_T, respectively) increased with control Tyrode perfusion but TNFα slowed CV_T alone relative to control and anisotropy of conduction increased, but not significantly. TNFα increased W_P relative to control at 90 mins, without significantly changing GJ coupling. Increasing extracellular calcium after 30 mins of just TNFα exposure increased CV_T within 15 mins. TNFα + high calcium also restored CV_T at 90 mins and reduced W_P to control values. Interestingly, TNFα + high calcium also improved GJ coupling at 90 mins, which along with reduced W_P may have contributed to increasing CV.

Conclusions: Elevating extracellular calcium during acute TNFα exposure reduces perinexal expansion, increases ephaptic, and GJ coupling, improves CV and may be a novel method for preventing inflammation induced CV slowing.

TNF Receptor 1/2 Predict Heart Failure Risk in Type 2 Diabetes Mellitus Patients

Inflammation plays an important role in heart failure and diabetes mellitus. Traditional serum markers have limited predictive value in heart failure and diabetes. TNFR1 and TNFR2 (TNFR1/2) have been proven to be strongly associated with heart failure and diabetes complications. This study aimed to assess the association of sTNFR1 and sTNFR2 levels and incidental HF risk in diabetes patients.We detected the mRNA, protein, and serum expression of TNFR1/2, their downstream signaling pathway protein NF-kB, and JNK expression and some traditional serum inflammatory markers in a heart failure group without diabetes mellitus or abnormal glucose tolerance (n = 84), a diabetes mellitus group without heart failure (n = 86), and a heart failure with diabetes mellitus group (n = 86).TNFR1/2 were significantly higher in patients with heart failure and diabetes mellitus based on mRNA expression to protein expression and serum expression. However, there were no differences in mRNA, protein, and serum levels of TNFR1/2 between the HF group and DM group. Furthermore, there were no differences between the groups in some traditional serum inflammatory markers.This study demonstrated higher expressions of TNFR, NF-kB, and JNK in patients with heart failure and diabetes mellitus. Compared with traditional serum markers, TNFR1 and TNFR2 are associated with heart failure risk in type 2 diabetes mellitus patients.

TNFα-induced downregulation of microRNA-186 contributes to apoptosis in rat primary cardiomyocytes

Progressive loss of cardiac cardiomyocytes is involved in pathogenesis of heart failure. Inflammation is considered as a major risk factor that triggers cardiomyocytes apoptosis or induces cellular damage. Proinflammatory cytokines such as TNFα can directly activate cell apoptosis or promote oxidant production that damages cellular structure eventually. We investigated TNFα mediated apoptosis in cultured rat primary cardiomyocytes. Annexin V/PI staining and apoptosis biomarker expression were used to examine cardiomyocytes cell apoptosis response. We also identified key microRNA that plays a regulatory role in this pathway with genetic and biochemical approaches. Apoptosis Inducing Factor (AIF) expression was found to be upregulated with 10μg/ml or 50μg/ml TNFα stimulation for 24h, which was associated with apoptotic index. Subsequently, miR-186 was identified as direct regulator of AIF in TNFα mediated cardiomyocytes apoptosis from microRNA expression profiling. miR-186 level was downregulated with TNFα treatment that was correlated with AIF induction. Last, in the rescue experiment, miR-186 mimic protected cardiomyocytes against TNFα mediated apoptosis. Collectively, the results suggest TNFα-induced AIF upregulation contributes to apoptosis in rat primary cardiomyocytes through regulating miR-186 expression, which implies miR-186 could be a potential therapeutic target for preventing inflammation associated cardiac damage.

Combined Inhibition of the Renin-Angiotensin System and Neprilysin Positively Influences Complex Mitochondrial Adaptations in Progressive Experimental Heart Failure

BACKGROUND

Inhibitors of the renin angiotensin system and neprilysin (RAS-/NEP-inhibitors) proved to be extraordinarily beneficial in systolic heart failure. Furthermore, compelling evidence exists that impaired mitochondrial pathways are causatively involved in progressive left ventricular (LV) dysfunction. Consequently, we aimed to assess whether RAS-/NEP-inhibition can attenuate mitochondrial adaptations in experimental heart failure (HF).

METHODS AND RESULTS

By progressive right ventricular pacing, distinct HF stages were induced in 15 rabbits, and 6 animals served as controls (CTRL). Six animals with manifest HF (CHF) were treated with the RAS-/NEP-inhibitor omapatrilat. Echocardiographic studies and invasive blood pressure measurements were undertaken during HF progression. Mitochondria were isolated from LV tissue, respectively, and further worked up for proteomic analysis using the SWATH technique. Enzymatic activities of citrate synthase and the electron transfer chain (ETC) complexes I, II, and IV were assessed. Ultrastructural analyses were performed by transmission electron microscopy. During progression to overt HF, intricate expression changes were mainly detected for proteins belonging to the tricarboxylic acid cycle, glucose and fat metabolism, and the ETC complexes, even though ETC complex I, II, or IV enzymatic activities were not significantly influenced. Treatment with a RAS-/NEP-inhibitor then reversed some maladaptive metabolic adaptations, positively influenced the decline of citrate synthase activity, and altered the composition of each respiratory chain complex, even though this was again not accompanied by altered ETC complex enzymatic activities. Finally, ultrastructural evidence pointed to a reduction of autophagolytic and degenerative processes with omapatrilat-treatment.

CONCLUSIONS

This study describes complex adaptations of the mitochondrial proteome in experimental tachycardia-induced heart failure and shows that a combined RAS-/NEP-inhibition can beneficially influence mitochondrial key pathways.

Exenatide Reduces Tumor Necrosis Factor-α-induced Apoptosis in Cardiomyocytes by Alleviating Mitochondrial Dysfunction

Background:

Tumor necrosis factor-α (TNF-α) plays an important role in progressive contractile dysfunction in several cardiac diseases. The cytotoxic effects of TNF-α are suggested to be partly mediated by reactive oxygen species (ROS)- and mitochondria-dependent apoptosis. Glucagon-like peptide-1 (GLP-1) or its analogue exhibits protective effects on the cardiovascular system. The objective of the study was to assess the effects of exenatide, a GLP-1 analogue, on oxidative stress, and apoptosis in TNF-α-treated cardiomyocytes in vitro.

Methods:

Isolated neonatal rat cardiomyocytes were divided into three groups: Control group, with cells cultured in normal conditions without intervention; TNF-α group, with cells incubated with TNF-α (40 ng/ml) for 6, 12, or 24 h without pretreatment with exenatide; and exenatide group, with cells pretreated with exenatide (100 nmol/L) 30 mins before TNF-α (40 ng/ml) stimulation. We evaluated apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay and flow cytometry, measured ROS production and mitochondrial membrane potential (MMP) by specific the fluorescent probes, and assessed the levels of proteins by Western blotting for all the groups.

Results:

Exenatide pretreatment significantly reduced cardiomyocyte apoptosis as measured by flow cytometry and TUNEL assay at 12 h and 24 h. Also, exenatide inhibited excessive ROS production and maintained MMP. Furthermore, declined cytochrome-c release and cleaved caspase-3 expression and increased bcl-2 expression with concomitantly decreased Bax activation were observed in exenatide-pretreated cultures.

Conclusion:

These results suggested that exenatide exerts a protective effect on cardiomyocytes, preventing TNF-α-induced apoptosis; the anti-apoptotic effects may be associated with protection of mitochondrial function.

Niemann-Pick type C2 deficiency impairs autophagy-lysosomal activity, mitochondrial function, and TLR signaling in adipocytes

In this study, we investigated the role and mechanism of Niemann-Pick type C (NPC)2 in regulating lysosomal activity, mitophagy, and mitochondrial function in adipocytes. We found that knocking down NPC2 impaired lysosomal activity, as evidenced by the reduced mature cathepsin B, the increased accumulation of light chain 3 (LC3) and p62, and the decreased autophagic flux. In NPC2-knockdown (kd) adipocytes, the starvation-induced conversion of LC3-I to LC3-II was abolished. More interestingly, the majority of NPC2 was found in the mitochondrial fraction, and NPC2 deficiency led to impaired autophagic flux and decreased induction of LC3-II in the mitochondrial fraction during mitochondrial stress. Moreover, cellular respiration profiling revealed that NPC2-kd adipocytes had significantly decreased basal/maximal respiration and mitochondrial gene expression compared with scrambled cells, suggesting mitochondrial dysfunction. Additionally, we found that the mitochondrial recruitment of LC3-II induced by lipopolysaccharide (LPS), but not TNFα, was blunted in NPC2-kd adipocytes. Most intriguingly, NPC2-kd selectively diminished LPS-induced NFκB and ERK1/2 phosphorylation and the expression of pro-inflammatory genes, indicating that toll-like receptor signaling activation is impaired in the absence of NPC2. Our results suggest that NPC2 is in a mitochondrially associated autophagosome and plays an important role in regulating mitophagy, mitochondrial quality control, and mitochondrial function.

Mitochondrial dysfunction in bipolar disorder: Evidence, pathophysiology and translational implications

Bipolar disorder (BD) is a chronic psychiatric illness characterized by severe and biphasic changes in mood. Several pathophysiological mechanisms have been hypothesized to underpin the neurobiology of BD, including the presence of mitochondrial dysfunction. A confluence of evidence points to an underlying dysfunction of mitochondria, including decreases in mitochondrial respiration, high-energy phosphates and pH; changes in mitochondrial morphology; increases in mitochondrial DNA polymorphisms; and downregulation of nuclear mRNA molecules and proteins involved in mitochondrial respiration. Mitochondria play a pivotal role in neuronal cell survival or death as regulators of both energy metabolism and cell survival and death pathways. Thus, in this review, we discuss the genetic and physiological components of mitochondria and the evidence for mitochondrial abnormalities in BD. The final part of this review discusses mitochondria as a potential target of therapeutic interventions in BD.

Intercellular Adhesion Molecule 1 Regulates Left Ventricular Leukocyte Infiltration, Cardiac Remodeling, and Function in Pressure Overload-Induced Heart Failure

Background

Left ventricular dysfunction and heart failure are strongly associated in humans with increased circulating levels of proinflammatory cytokines, T cells, and soluble intercellular cell adhesion molecule 1 (ICAM1). In mice, infiltration of T cells into the left ventricle contributes to pathological cardiac remodeling, but the mechanisms regulating their recruitment to the heart are unclear. We hypothesized that ICAM1 regulates cardiac inflammation and pathological cardiac remodeling by mediating left ventricular T‐cell recruitment and thus contributing to cardiac dysfunction and heart failure.

Methods and Results

In a mouse model of pressure overload–induced heart failure, intramyocardial endothelial ICAM1 increased within 48 hours in response to thoracic aortic constriction and remained upregulated as heart failure progressed. ICAM1‐deficient mice had decreased T‐cell and proinflammatory monocyte infiltration in the left ventricle in response to thoracic aortic constriction, despite having numbers of circulating T cells and activated T cells in the heart‐draining lymph nodes that were similar to those of wild‐type mice. ICAM1‐deficient mice did not develop cardiac fibrosis or systolic and diastolic dysfunction in response to thoracic aortic constriction. Exploration of the mechanisms regulating ICAM1 expression revealed that endothelial ICAM1 upregulation and T‐cell infiltration were not mediated by endothelial mineralocorticoid receptor signaling, as demonstrated in thoracic aortic constriction studies in mice with endothelial mineralocorticoid receptor deficiency, but rather were induced by the cardiac cytokines interleukin 1β and 6.

Conclusions

ICAM1 regulates pathological cardiac remodeling by mediating proinflammatory leukocyte infiltration in the left ventricle and cardiac fibrosis and dysfunction and thus represents a novel target for treatment of heart failure.

Knockdown of TNF-α by DNAzyme gold nanoparticles as an anti-inflammatory therapy for myocardial infarction

In this study, we used deoxyribozyme (DNAzyme) functionalized gold nanoparticles (AuNPs) to catalytically silence tumor necrosis factor-α (TNF-α) in vivo as a potential therapeutic for myocardial infarction (MI). Using primary macrophages as a model, we demonstrated 50% knockdown of TNF-α, which was not attainable using Lipofectamine-based approaches. Local injection of DNAzyme conjugated to gold particles (AuNPs) in the rat myocardium yielded TNF-α knockdown efficiencies of 50%, which resulted in significant anti-inflammatory effects and improvement in acute cardiac function following MI. Our results represent the first example showing the use of DNAzyme AuNP conjugates in vivo for viable delivery and gene regulation. This is significant as TNF-α is a multibillion dollar drug target implicated in many inflammatory-mediated disorders, thus underscoring the potential impact of DNAzyme-conjugated AuNPs.

Regulation of cardiac microRNAs induced by aerobic exercise training during heart failure

Exercise training (ET) has beneficial effects on the myocardium in heart failure (HF) patients and in animal models of induced cardiac hypertrophy and failure. We hypothesized that if microRNAs (miRNAs) respond to changes following cardiac stress, then myocardial profiling of these miRNAs may reveal cardio-protective mechanisms of aerobic ET in HF. We used ascending aortic stenosis (AS) inducing HF in Wistar rats. Controls were sham-operated animals. At 18 wk after surgery, rats with cardiac dysfunction were randomized to 10 wk of aerobic ET (HF-ET) or to a heart failure sedentary group (HF-S). ET attenuated cardiac remodeling as well as clinical and pathological signs of HF with maintenance of systolic and diastolic function when compared with that of the HF-S. Global miRNA expression profiling of the cardiac tissue revealed 53 miRNAs exclusively dysregulated in animals in the HF-ET, but only 11 miRNAs were exclusively dysregulated in the HF-S. Out of 23 miRNAs that were differentially regulated in both groups, 17 miRNAs exhibited particularly high increases in expression, including miR-598, miR-429, miR-224, miR-425, and miR-221. From the initial set of deregulated miRNAs, 14 miRNAs with validated targets expressed in cardiac tissue that respond robustly to ET in HF were used to construct miRNA-mRNA regulatory networks that revealed a set of 203 miRNA-target genes involved in programmed cell death, TGF-β signaling, cellular metabolic processes, cytokine signaling, and cell morphogenesis. Our findings reveal that ET attenuates cardiac abnormalities during HF by regulating cardiac miRNAs with a potential role in cardio-protective mechanisms through multiple effects on gene expression.

Myocardial Dysfunction and Shock after Cardiac Arrest

Postarrest myocardial dysfunction includes the development of low cardiac output or ventricular systolic or diastolic dysfunction after cardiac arrest. Impaired left ventricular systolic function is reported in nearly two-thirds of patients resuscitated after cardiac arrest. Hypotension and shock requiring vasopressor support are similarly common after cardiac arrest. Whereas shock requiring vasopressor support is consistently associated with an adverse outcome after cardiac arrest, the association between myocardial dysfunction and outcomes is less clear. Myocardial dysfunction and shock after cardiac arrest develop as the result of preexisting cardiac pathology with multiple superimposed insults from resuscitation. The pathophysiology involves cardiovascular ischemia/reperfusion injury and cardiovascular toxicity from excessive levels of inflammatory cytokine activation and catecholamines, among other contributing factors. Similar mechanisms occur in myocardial dysfunction after cardiopulmonary bypass, in sepsis, and in stress-induced cardiomyopathy. Hemodynamic stabilization after resuscitation from cardiac arrest involves restoration of preload, vasopressors to support arterial pressure, and inotropic support if needed to reverse the effects of myocardial dysfunction and improve systemic perfusion. Further research is needed to define the role of postarrest myocardial dysfunction on cardiac arrest outcomes and identify therapeutic strategies.

The many roads to mitochondrial dysfunction in neuroimmune and neuropsychiatric disorders

BACKGROUND

Mitochondrial dysfunction and defects in oxidative metabolism are a characteristic feature of many chronic illnesses not currently classified as mitochondrial diseases. Examples of such illnesses include bipolar disorder, multiple sclerosis, Parkinson's disease, schizophrenia, depression, autism, and chronic fatigue syndrome.

DISCUSSION

While the majority of patients with multiple sclerosis appear to have widespread mitochondrial dysfunction and impaired ATP production, the findings in patients diagnosed with Parkinson's disease, autism, depression, bipolar disorder schizophrenia and chronic fatigue syndrome are less consistent, likely reflecting the fact that these diagnoses do not represent a disease with a unitary pathogenesis and pathophysiology. However, investigations have revealed the presence of chronic oxidative stress to be an almost invariant finding in study cohorts of patients afforded each diagnosis. This state is characterized by elevated reactive oxygen and nitrogen species and/or reduced levels of glutathione, and goes hand in hand with chronic systemic inflammation with elevated levels of pro-inflammatory cytokines.

SUMMARY

This paper details mechanisms by which elevated levels of reactive oxygen and nitrogen species together with elevated pro-inflammatory cytokines could conspire to pave a major road to the development of mitochondrial dysfunction and impaired oxidative metabolism seen in many patients diagnosed with these disorders.