SGLT2 inhibitor ertugliflozin decreases elevated intracellular sodium, and improves energetics and contractile function in diabetic cardiomyopathy.

Background: Elevated myocardial intracellular sodium ([Na]) was shown to decrease mitochondrial calcium ([Ca]) via mitochondrial sodium/calcium exchanger (NCX), resulting in decreased mitochondrial ATP synthesis. The sodium-glucose co-transporter 2 inhibitor (SGLT2i) ertugliflozin (ERTU) improved energetic deficit and contractile dysfunction in a mouse model of high fat, high sucrose (HFHS) diet-induced diabetic cardiomyopathy (DCMP). As SGLT2is were shown to lower [Na] in isolated cardiomyocytes, we hypothesized that energetic improvement in DCMP is at least partially mediated by a decrease in abnormally elevated myocardial [Na].

Effects of Sodium-Glucose Linked Transporter 2 Inhibition With Ertugliflozin on Mitochondrial Function, Energetics, and Metabolic Gene Expression in the Presence and Absence of Diabetes Mellitus in Mice.

Background Inhibitors of the sodium-glucose linked transporter 2 improve cardiovascular outcomes in patients with or without type 2 diabetes mellitus, but the effects on cardiac energetics and mitochondrial function are unknown. We assessed the effects of sodium-glucose linked transporter 2 inhibition on mitochondrial function, high-energy phosphates, and genes encoding mitochondrial proteins in hearts of mice with and without diet-induced diabetic cardiomyopathy. Methods and Results Mice fed a control diet or a high-fat, high-sucrose diet received ertugliflozin mixed with the diet (0.

Redox-Resistant SERCA [Sarco(endo)plasmic Reticulum Calcium ATPase] Attenuates Oxidant-Stimulated Mitochondrial Calcium and Apoptosis in Cardiac Myocytes and Pressure Overload-Induced Myocardial Failure in Mice.

Background: SERCA [sarco(endo)plasmic reticulum calcium ATPase] is regulated by oxidative posttranslational modifications at cysteine 674 (C674). Because sarcoplasmic reticulum (SR) calcium has been shown to play a critical role in mediating mitochondrial dysfunction in response to reactive oxygen species, we hypothesized that SERCA oxidation at C674 would modulate the effects of reactive oxygen species on mitochondrial calcium and mitochondria-dependent apoptosis in cardiac myocytes.

Methods: Adult rat ventricular myocytes expressing wild-type SERCA2b or a redox-insensitive mutant in which C674 is replaced by serine (C674S) were exposed to HO (100 µmol/Lμ).

Differential Effects of Sacubitril/Valsartan on Diastolic Function in Mice With Obesity-Related Metabolic Heart Disease.

Mice with obesity and metabolic heart disease (MHD) due to a high-fat, high-sucrose diet were treated with placebo, a clinically relevant dose of sacubitril (SAC)/valsartan (VAL), or an equivalent dose of VAL for 4 months. There were striking differences between SAC/VAL and VAL with regard to: 1) diastolic dysfunction; 2) interstitial fibrosis; and to a lesser degree; 3) oxidative stress-all of which were more favorably affected by SAC/VAL. SAC/VAL and VAL similarly attenuated myocardial hypertrophy and improved myocardial energetics.

A novel tracer for in vivo optical imaging of fatty acid metabolism in the heart and brown adipose tissue.

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.

Increasing mitochondrial ATP synthesis with butyrate normalizes ADP and contractile function in metabolic heart disease.

Metabolic heart disease (MHD), which is strongly associated with heart failure with preserved ejection fraction, is characterized by reduced mitochondrial energy production and contractile performance. In this study, we tested the hypothesis that an acute increase in ATP synthesis, via short chain fatty acid (butyrate) perfusion, restores contractile function in MHD. Isolated hearts of mice with MHD due to consumption of a high fat high sucrose (HFHS) diet or on a control diet (CD) for 4 months were studied using P NMR spectroscopy to measure high energy phosphates and ATP synthesis rates during increased work demand.

Unlocking the Secrets of Mitochondria in the Cardiovascular System: Path to a Cure in Heart Failure—A Report from the 2018 National Heart, Lung, and Blood Institute Workshop.

Mitochondria have emerged as a central factor in the pathogenesis and progression of heart failure, and other cardiovascular diseases, as well, but no therapies are available to treat mitochondrial dysfunction. The National Heart, Lung, and Blood Institute convened a group of leading experts in heart failure, cardiovascular diseases, and mitochondria research in August 2018. These experts reviewed the current state of science and identified key gaps and opportunities in basic, translational, and clinical research focusing on the potential of mitochondria-based therapeutic strategies in heart failure.

Genetically targeted fluorescent probes reveal dynamic calcium responses to adrenergic signaling in multiple cardiomyocyte compartments.

Calcium (Ca), an important second messenger, regulates many cellular activities and varies spatiotemporally within the cell. Conventional methods to monitor Ca changes, such as synthetic Ca indicators, are not targetable, while genetically encoded Ca indicators (GECI) can be precisely directed to cellular compartments. GECIs are chimeric proteins composed of calmodulin (or other proteins that change conformation on Ca binding) coupled with two fluorescent proteins that come closer together after an increase in [Ca], and enhance Förster resonance energy transfer (FRET) that allows for ratiometric [Ca] assessment.

Energetic Dysfunction Is Mediated by Mitochondrial Reactive Oxygen Species and Precedes Structural Remodeling in Metabolic Heart Disease.

Metabolic syndrome is associated with metabolic heart disease (MHD) that is characterized by left ventricular (LV) hypertrophy, interstitial fibrosis, contractile dysfunction, and mitochondrial dysfunction. Overexpression of catalase in mitochondria (transgenic expression of catalase targeted to the mitochondria [mCAT]) prevents the structural and functional features of MHD caused by a high-fat, high-sucrose (HFHS) diet for ≥4 months. However, it is unclear whether the effect of mCAT is due to prevention of reactive oxygen species (ROS)-mediated cardiac remodeling, a direct effect on mitochondrial function, or both.

Galectin-3 Is Associated With Stage B Metabolic Heart Disease and Pulmonary Hypertension in Young Obese Patients.

Background Obesity is a precursor to heart failure with preserved ejection fraction. Biomarkers that identify preclinical metabolic heart disease ( MHD ) in young obese patients would help identify high-risk individuals for heart failure prevention strategies. We assessed the predictive value of GAL3 (galectin-3), FSTL3 (follistatin-like 3 peptide), and NT-proBNP (N-terminal pro-B-type natriuretic peptide) to identify stage B MHD in young obese participants free of clinically evident cardiovascular disease.

Oxidative modifications of mitochondrial complex II are associated with insulin resistance of visceral fat in obesity.

Obesity, particularly visceral adiposity, has been linked to mitochondrial dysfunction and increased oxidative stress, which have been suggested as mechanisms of insulin resistance. The mechanism(s) behind this remains incompletely understood. In this study, we hypothesized that mitochondrial complex II dysfunction plays a role in impaired insulin sensitivity in visceral adipose tissue of subjects with obesity.

Myocardial Redox Hormesis Protects the Heart of Female Mice in Sepsis.

Mice challenged with lipopolysaccharide develop cardiomyopathy in a sex and redox-dependent fashion. Here we extended these studies to the cecal ligation and puncture (CLP) model.We compared male and female FVB mice (wild type, WT) and transgenic littermates overexpressing myocardial catalase (CAT).

Multiplexed Optical Imaging of Energy Substrates Reveals That Left Ventricular Hypertrophy Is Associated With Brown Adipose Tissue Activation.

Background: Substrate utilization in tissues with high energetic requirements could play an important role in cardiometabolic disease. Current techniques to assess energetics are limited by high cost, low throughput, and the inability to resolve multiple readouts simultaneously. Consequently, we aimed to develop a multiplexed optical imaging platform to simultaneously assess energetics in multiple organs in a high throughput fashion.

Decreased ATP production and myocardial contractile reserve in metabolic heart disease.

Metabolic syndrome is a cluster of obesity-related metabolic abnormalities that lead to metabolic heart disease (MHD) with left ventricular pump dysfunction. Although MHD is thought to be associated with myocardial energetic deficiency, two key questions have not been answered. First, it is not known whether there is a sufficient energy deficit to contribute to pump dysfunction.

Benefit-Risk Assessment of Crataegus Extract WS 1442: An Evidence-Based Review.

Preparations from Crataegus (hawthorn) have a long history in the treatment of heart failure. WS 1442 is a dry extract from hawthorn leaves with flowers (4-6.6:1), extraction solvent of ethanol 45% (w/w), adjusted to 17.

Preclinical Alterations in Myocardial Microstructure in People with Metabolic Syndrome.

Objective: Metabolic syndrome (MetS) can lead to myocardial fibrosis, diastolic dysfunction, and eventual heart failure. This study evaluated alterations in myocardial microstructure in people with MetS by using a novel algorithm to characterize ultrasonic signal intensity variation.

Methods: Among 254 participants without existing cardiovascular disease (mean age 42 ± 11 years, 75% women), there were 162 with MetS, 47 with obesity without MetS, and 45 nonobese controls.

Up-regulation of Intracellular Calcium Handling Underlies the Recovery of Endotoxemic Cardiomyopathy in Mice.

Background: In surviving patients, sepsis-induced cardiomyopathy is spontaneously reversible. In the absence of any experimental data, it is generally thought that cardiac recovery in sepsis simply follows the remission of systemic inflammation. Here the authors aimed to identify the myocardial mechanisms underlying cardiac recovery in endotoxemic mice.

Expert consensus document: Mitochondrial function as a therapeutic target in heart 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.

Short-term caloric restriction in db/db mice improves myocardial function and increases high molecular weight (HMW) adiponectin.

Background: Obesity and metabolic syndrome lead to the development of metabolic heart disease (MHD) that is characterized by left ventricular hypertrophy (LVH), diastolic dysfunction, and increased mitochondrial ROS. Caloric restriction (CR) is a nutritional intervention that protects against obesity, diabetes, and cardiovascular disease. Healthy adipose tissue is cardioprotective releasing adipokines such as adiponectin.

Distinct Myocardial Mechanisms Underlie Cardiac Dysfunction in Endotoxemic Male and Female Mice.

In male mice, sepsis-induced cardiomyopathy develops as a result of dysregulation of myocardial calcium (Ca) handling, leading to depressed cellular Ca transients (ΔCai). ΔCai depression is partially due to inhibition of sarcoplasmic reticulum Ca ATP-ase (SERCA) via oxidative modifications, which are partially opposed by cGMP generated by the enzyme soluble guanylyl cyclase (sGC). Whether similar mechanisms underlie sepsis-induced cardiomyopathy in female mice is unknown.

Developing New Treatments for Heart Failure: Focus on the Heart.

Compared with heart failure (HF) care 20 to 30 years ago, there has been tremendous advancement in therapy for ambulatory HF with reduced ejection fraction with the use of agents that block maladaptive neurohormonal pathways. However, during the past decade, with few notable exceptions, the frequency of successful drug development programs has fallen as most novel therapies have failed to offer incremental benefit or raised safety concerns (ie, hypotension). Moreover, no therapy has been approved specifically for HF with preserved ejection fraction or for worsening chronic HF (including acutely decompensated HF).

Mitochondrial Reactive Oxygen Species Mediate Cardiac Structural, Functional, and Mitochondrial Consequences of Diet-Induced Metabolic Heart Disease.

Background: Mitochondrial reactive oxygen species (ROS) are associated with metabolic heart disease (MHD). However, the mechanism by which ROS cause MHD is unknown. We tested the hypothesis that mitochondrial ROS are a key mediator of MHD.

Partial Liver Kinase B1 (LKB1) Deficiency Promotes Diastolic Dysfunction, De Novo Systolic Dysfunction, Apoptosis, and Mitochondrial Dysfunction With Dietary Metabolic Challenge.

Background: Myocardial hypertrophy and dysfunction are key features of metabolic heart disease due to dietary excess. Metabolic heart disease manifests primarily as diastolic dysfunction but may progress to systolic dysfunction, although the mechanism is poorly understood. Liver kinase B1 (LKB1) is a key activator of AMP-activated protein kinase and possibly other signaling pathways that oppose myocardial hypertrophy and failure.

Overexpression of Catalase Diminishes Oxidative Cysteine Modifications of Cardiac Proteins.

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.

Preclinical Systolic and Diastolic Dysfunctions in Metabolically Healthy and Unhealthy Obese Individuals.

Background: Despite the substantial overlap of obesity and metabolic disease, there is heterogeneity with respect to cardiovascular risk. We sought to investigate preclinical differences in systolic and diastolic function in obesity, and specifically compare obese individuals with and without metabolic syndrome (MS).

Methods And Results: Obese individuals without cardiac disease with (OB/MS+, n=124) and without (OB/MS-, n=37) MS were compared with nonobese controls (n=29).