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Patients with diabetes and other obesity-linked conditions have increased susceptibility to cardiovascular disorders 1 . The adipocytokine adiponectin is decreased in patients with obesity-linked diseases 2 . Here, we found that pressure overload in adiponectin-deficient mice resulted in enhanced concentric cardiac hypertrophy and increased mortality that was associated with increased extracellular signal-regulated kinase (ERK) and diminished AMP-activated protein kinase (AMPK) signaling in the myocardium. Adenovirus-mediated supplemention of adiponectin attenuated cardiac hypertrophy in response to pressure overload in adiponectin-deficient, wild-type and diabetic db / db mice. In cultures of cardiac myocytes, adiponectin activated AMPK and inhibited agonist-stimulated hypertrophy and ERK activation. Transduction with a dominant-negative form of AMPK reversed these effects, suggesting that adiponectin inhibits hypertrophic signaling in the myocardium through activation of AMPK signaling. Adiponectin may have utility for the treatment of hypertrophic cardiomyopathy associated with diabetes and other obesity-related diseases.

Multiplexed imaging is essential for the evaluation of substrate utilization in metabolically active organs, such as the heart and brown adipose tissue (BAT), where substrate preference changes in pathophysiologic states. Optical imaging provides a useful platform because of its low cost, high throughput and intrinsic ability to perform composite readouts. However, the paucity of probes available for in vivo use has limited optical methods to image substrate metabolism. Here, we present a novel near-infrared (NIR) free fatty acid (FFA) tracer suitable for in vivo imaging of deep tissues such as the heart. Using click chemistry, Alexa Fluor 647 DIBO Alkyne was conjugated to palmitic acid. Mice injected with 0.05 nmol/g bodyweight of the conjugate (AlexaFFA) were subjected to conditions known to increase FFA uptake in the heart (fasting) and BAT [cold exposure and injection with the β 3 adrenergic agonist CL 316, 243(CL)]. Organs were subsequently imaged both ex vivo and in vivo to quantify AlexaFFA uptake. The blood kinetics of AlexaFFA followed a two-compartment model with an initial fast compartment half-life of 0.14 h and a subsequent slow compartment half-life of 5.2 h, consistent with reversible protein binding. Ex vivo fluorescence imaging after overnight cold exposure and fasting produced a significant increase in AlexaFFA uptake in the heart (58 ± 12%) and BAT (278 ± 19%) compared to warm/fed animals. In vivo imaging of the heart and BAT after exposure to CL and fasting showed a significant increase in AlexaFFA uptake in the heart (48 ± 20%) and BAT (40 ± 10%) compared to saline-injected/fed mice. We present a novel near-infrared FFA tracer, AlexaFFA, that is suitable for in vivo quantification of FFA metabolism and can be applied in the context of a low cost, high throughput, and multiplexed optical imaging platform.

Reactive protein cysteine thiolates are instrumental in redox regulation. Oxidants, such as hydrogen peroxide (H2O2), react with thiolates to form oxidative post-translational modifications, enabling physiological redox signaling. Cardiac disease and aging are associated with oxidative stress which can impair redox signaling by altering essential cysteine thiolates. We previously found that cardiac-specific overexpression of catalase (Cat), an enzyme that detoxifies excess H2O2, protected from oxidative stress and delayed cardiac aging in mice. Using redox proteomics and systems biology, we sought to identify the cysteines that could play a key role in cardiac disease and aging. With a 'Tandem Mass Tag' (TMT) labeling strategy and mass spectrometry, we investigated differential reversible cysteine oxidation in the cardiac proteome of wild type and Cat transgenic (Tg) mice. Reversible cysteine oxidation was measured as thiol occupancy, the ratio of total available versus reversibly oxidized cysteine thiols. Catalase overexpression globally decreased thiol occupancy by ≥1.3 fold in 82 proteins, including numerous mitochondrial and contractile proteins. Systems biology analysis assigned the majority of proteins with differentially modified thiols in Cat Tg mice to pathways of aging and cardiac disease, including cellular stress response, proteostasis, and apoptosis. In addition, Cat Tg mice exhibited diminished protein glutathione adducts and decreased H2O2 production from mitochondrial complex I and II, suggesting improved function of cardiac mitochondria. In conclusion, our data suggest that catalase may alleviate cardiac disease and aging by moderating global protein cysteine thiol oxidation.

Evidence suggests that inflammatory mediators contribute to development and progression of chronic heart failure. We therefore tested the hypothesis that immunomodulation might counteract this pathophysiological mechanism in patients. We did a double-blind, placebo-controlled study of a device-based non-specific immunomodulation therapy (IMT) in patients with New York Heart Association (NYHA) functional class II–IV chronic heart failure, left ventricular (LV) systolic dysfunction, and hospitalisation for heart failure or intravenous drug therapy in an outpatient setting within the past 12 months. Patients were randomly assigned to receive IMT (n=1213) or placebo (n=1213) by intragluteal injection on days 1, 2, 14, and every 28 days thereafter. Primary endpoint was the composite of time to death from any cause or first hospitalisation for cardiovascular reasons. The study continued until 828 primary endpoint events had accrued and all study patients had been treated for at least 22 weeks. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00111969. During a mean follow-up of 10·2 months, there were 399 primary events in the IMT group and 429 in the placebo group (hazard ratio 0·92; 95% CI 0·80–1·05; p=0·22). In two prespecified subgroups of patients—those with no history of previous myocardial infarction (n=919) and those with NYHA II heart failure (n=689)—IMT was associated with a 26% (0·74; 0·57–0·95; p=0·02) and a 39% (0·61; 95% CI 0·46–0·80; p=0·0003) reduction in the risk of primary endpoint events, respectively. Non-specific immunomodulation may have a role as a potential treatment for a large segment of the heart failure population, which includes patients without a history of myocardial infarction (irrespective of their functional NYHA class) and patients within NYHA class II.

Metabolic syndrome (MS) is commonly associated with left ventricular (LV) diastolic dysfunction and LV hypertrophy. We sought to examine whether preclinical LV diastolic dysfunction can occur independent of LV hypertrophy in MS. We recruited 90 consecutive participants with MS and without cardiovascular disease (mean age 46 years, 78% women) and 26 controls (no risk factors for MS; mean age 43 years, 65% women). Participants underwent echocardiography with tissue Doppler imaging. In age- and gender-adjusted analyses, MS was associated with higher left atrial (LA) diameter, higher LV mass, lower E/A ratio, and lower mean e′ (p <0.001 for all). These associations remained significant after further adjusting for blood pressure, antihypertensive medication use, and body mass index. After adjusting for LV mass, MS remained independently associated with higher LA diameter, lower E/A ratio, and lower mean e′ (p ≤0.01 for all). Specifically, subjects with MS had a 1.8 cm/s lower mean e′ compared with controls (p = 0.01). Notably, differences in mean e′ between those with and without MS were more pronounced at younger ages (p for interaction = 0.003). In conclusion, MS was associated with preclinical LV diastolic dysfunction independent of LV mass, as reflected by higher LA diameter, lower E/A ratio, and lower mean e′. This suggests that MS can lead to the development of diastolic dysfunction through mechanisms independent of hypertrophy. Differences in diastolic function were more pronounced at younger ages, highlighting the potential importance of early risk factor modification and preventive strategies in MS.

Dysregulation of the myocardial extracellular matrix contributes to abnormal cardiac muscle function. Changes in the balance between matrix deposition and matrix degradation by matrix metalloproteinases (MMPs) can lead to cardiac fibrosis and dilation. In this review, we discuss the regulation of MMPs, their endogenous inhibitors (TIMPs) and collagen synthesis by inflammatory cytokines and reactive oxygen/nitrogen species (ROS/RNS). Inflammatory cytokines, such as interleukin-1beta and tumor necrosis factor-alpha, and ROS activate mitogen-activated protein kinases and stress-responsive protein kinases in cardiac cells. In non-cardiac tissues, inflammatory cytokine activation of these kinases is redox sensitive, suggesting ROS may also be involved in cytokine signaling in the heart. Subsequent activation of transcription factors including AP-1, Ets, and nuclear factor kappa-B leads to increased transcription of MMPs. ROS also directly activate MMPs post-translationally. In addition, inflammatory cytokines and ROS lead to decreased TIMP levels and collagen synthesis. Work in animal models suggests that inhibition of inflammatory cytokine or ROS signaling leads to less myocardial remodeling. Further study of the signaling of regulation of the cardiac extracellular matrix may lead to new approaches for the treatment of myocardial remodeling and failure.

Heart failure is a pressing worldwide public-health problem with millions of patients having worsening heart failure. Despite all the available therapies, the condition carries a very poor prognosis. Existing therapies provide symptomatic and clinical benefit, but do not fully address molecular abnormalities that occur in cardiomyocytes. This shortcoming is particularly important given that most patients with heart failure have viable dysfunctional myocardium, in which an improvement or normalization of function might be possible. Although the pathophysiology of heart failure is complex, mitochondrial dysfunction seems to be an important target for therapy to improve cardiac function directly. Mitochondrial abnormalities include impaired mitochondrial electron transport chain activity, increased formation of reactive oxygen species, shifted metabolic substrate utilization, aberrant mitochondrial dynamics, and altered ion homeostasis. In this Consensus Statement, insights into the mechanisms of mitochondrial dysfunction in heart failure are presented, along with an overview of emerging treatments with the potential to improve the function of the failing heart by targeting mitochondria.

Symptomatic decompensation is the most common reason for the hospitalization of patients with congestive heart failure due to left ventricular systolic dysfunction. In such patients, the predominant symptoms — dyspnea and fatigue — are associated with pulmonary venous congestion and low cardiac output. 1 Accordingly, the primary goal of therapy, which is the rapid relief of symptoms, is usually approached with the use of intravenous diuretics, vasodilators, and positive inotropic agents to decrease cardiac filling pressures and increase cardiac output. 2 Although it has generally been assumed that improved hemodynamic function will result in the resolution of symptoms in patients with decompensated . . .

The pathophysiology of heart failure is complex, but mitochondrial dysfunction is an emerging therapeutic target to improve cardiac function. In this Consensus Statement, insights into the mechanisms of mitochondrial dysfunction in heart failure are presented, along with an overview of emerging treatments with the potential to improve the function of the failing heart by targeting mitochondria. Heart failure is a pressing worldwide public-health problem with millions of patients having worsening heart failure. Despite all the available therapies, the condition carries a very poor prognosis. Existing therapies provide symptomatic and clinical benefit, but do not fully address molecular abnormalities that occur in cardiomyocytes. This shortcoming is particularly important given that most patients with heart failure have viable dysfunctional myocardium, in which an improvement or normalization of function might be possible. Although the pathophysiology of heart failure is complex, mitochondrial dysfunction seems to be an important target for therapy to improve cardiac function directly. Mitochondrial abnormalities include impaired mitochondrial electron transport chain activity, increased formation of reactive oxygen species, shifted metabolic substrate utilization, aberrant mitochondrial dynamics, and altered ion homeostasis. In this Consensus Statement, insights into the mechanisms of mitochondrial dysfunction in heart failure are presented, along with an overview of emerging treatments with the potential to improve the function of the failing heart by targeting mitochondria.

A major determinant of maximal exercise capacity is the delivery of oxygen to exercising muscles, myo-lnositol trispyrophosphate (ITPP) is a recently identified membrane-permeant molecule that causes allosteric regulation of Hb oxygen binding affinity. In normal mice, i. p. administration of ITPP (0.5-3 g/ kg) caused a dose-related increase in the oxygen tension at which Hb is 50% saturated (p50), with a maximal increase of 31%. In parallel experiments, ITPP caused a dose-related increase in maximal exercise capacity, with a maximal increase of 57 ± 13% (P = 0.002). In transgenic mice with severe heart failure caused by cardiacspecific overexpression of Gαq. i. p. ITPP increased exercise capacity, with a maximal increase of 63 ± 7% (P = 0.005). Oral administration of ITPP in drinking water increased Hb p50 and maximal exercise capacity (+ 34 ± 10%; P < 0.002) in normal and failing mice. Consistent with increased tissue oxygen availability, ITPP decreased hypoxia inducible factor-1α mRNA expression in myocardium. It had no effect on myocardial contractility in isolated mouse cardiac myocytes and did not affect arterial blood pressure in vivo in mice. Thus, ITPP decreases the oxygen binding affinity of Hb, increases tissue oxygen delivery, and increases maximal exercise capacity in normal mice and mice with severe heart failure. ITPP is thus an attractive candidate for the therapy of patients with reduced exercise capacity caused by heart failure.