Search

Myocardial infarction (MI) is the most common cause of heart failure (HF), the leading cause of death in the developed world. Oxidative stress due to excessive production of reactive oxygen species (ROS) plays a key role in the pathogenesis of cardiac remodeling leading to HF. NADPH oxidase with Nox2 as the catalytic subunit is a major source for cardiac ROS production. Nox2-NADPH expression is significantly increased in the infarcted myocardium, primarily in neutrophils, macrophages and myocytes. Moreover, mice lacking the Nox2 gene are protected from ischemic injury, implicating Nox2 as a potential therapeutic target. RNAi-mediated gene silencing holds great promise as a therapeutic owing to its high specificity and potency. However, in vivo delivery hurdles have limited its effective clinical use. Here, we demonstrate acid-degradable polyketal particles as delivery vehicles for Nox2-siRNA to the post-MI heart. In vitro, Nox2-siRNA particles are effectively taken up by macrophages and significantly knockdown Nox2 expression and activity. Following in vivo intramyocardial injection in experimental mice models of MI, Nox2-siRNA particles prevent upregulation of Nox2 and significantly recovered cardiac function. This study highlights the potential of polyketals as siRNA delivery vehicles to the MI heart and represents a viable therapeutic approach for targeting oxidative stress.

Accumulation of excess lipids is associated with heart failure. The effects of transgenic expression of diacylglycerol acyl transferase 1 (DGAT1) in cardiomyocytes is controversial. We explored whether mice expressing DGAT1 via the myosin heavy chain (MHC) promoter develop heart dysfunction with aging or after crossing with mice over expressing peroxisome proliferator-activated receptor γ (PPARγ) in the heart. MHC-DGAT1 transgenic mice had increased heart triglyceride but no evidence of heart dysfunction, even up to age 12 months. The MHC-DGAT1 transgene improved heart dysfunction and survival of MHC-PPARγ-expressing transgenic mice. Both diacylglycerol and ceramide levels in the heart were reduced by this cross, as were the levels of several mRNAs of genes involved in lipid metabolism. There were fewer large lipid droplets in MHC-DGAT1×MHC-PPARγ mice compared with MHC-PPARγ, but total lipid content was not changed. Therefore, overexpression of DGAT1 is not toxic to the heart but reduces levels of toxic lipids and improves lipotoxic cardiomyopathy. Moreover, the beneficial effects of DGAT1 illustrate the interrelationship of several lipid metabolic pathways and the difficulty of assigning benefit to an isolated change in one potentially toxic lipid species.

Background— Heart failure is associated with impaired myocardial metabolism with a shift from fatty acids to glucose use for ATP generation. We hypothesized that cardiac accumulation of toxic lipid intermediates inhibits insulin signaling in advanced heart failure and that mechanical unloading of the failing myocardium corrects impaired cardiac metabolism. Methods and Results— We analyzed the myocardium and serum of 61 patients with heart failure (body mass index, 26.5±5.1 kg/m 2 ; age, 51±12 years) obtained during left ventricular assist device implantation and at explantation (mean duration, 185±156 days) and from 9 control subjects. Systemic insulin resistance in heart failure was accompanied by decreased myocardial triglyceride and overall fatty acid content but increased toxic lipid intermediates, diacylglycerol, and ceramide. Increased membrane localization of protein kinase C isoforms, inhibitors of insulin signaling, and decreased activity of insulin signaling molecules Akt and Foxo were detectable in heart failure compared with control subjects. Left ventricular assist device implantation improved whole-body insulin resistance (homeostatic model of analysis–insulin resistance, 4.5±0.6–3.2±0.5; P Conclusions— Mechanical unloading after left ventricular assist device implantation corrects systemic and local metabolic derangements in advanced heart failure, leading to reduced myocardial levels of toxic lipid intermediates and improved cardiac insulin signaling.

The role of serine palmitoyltransferase (SPT) and de novo ceramide biosynthesis in cardiac ceramide and sphingomyelin metabolism is unclear. To determine whether the de novo synthetic pathways, rather than ceramide uptake from circulating lipoproteins, is important for heart ceramide levels, we created cardiomyocyte-specific deficiency of Sptlc2, a subunit of SPT. Heart-specific Sptlc2-deficient (hSptlc2 KO) mice had a >35% reduction in ceramide, which was limited to C18:0 and very long chain ceramides. Sphingomyelinase expression, and levels of sphingomyelin and diacylglycerol were unchanged. But surprisingly phospholipids and acyl CoAs contained increased saturated long chain fatty acids. hSptlc2 KO mice had decreased fractional shortening and thinning of the cardiac wall. While the genes regulating glucose and fatty acid metabolism were not changed, expression of cardiac failure markers and the genes involved in the formation of extracellular matrices were up-regulated in hSptlc2 KO hearts. In addition, ER-stress markers were up-regulated leading to increased apoptosis. These results suggest that Sptlc2-mediated de novo ceramide synthesis is an essential source of C18:0 and very long chain, but not of shorter chain, ceramides in the heart. Changes in heart lipids other than ceramide levels lead to cardiac toxicity.

Background— Diabetes mellitus and obesity, which confer an increased risk of sudden cardiac death, are associated with cardiomyocyte lipid accumulation and altered cardiac electric properties, manifested by prolongation of the QRS duration and QT interval. It is difficult to distinguish the contribution of cardiomyocyte lipid accumulation from the contribution of global metabolic defects to the increased incidence of sudden death and electric abnormalities. Methods and Results— In order to study the effects of metabolic abnormalities on arrhythmias without the complex systemic effects of diabetes mellitus and obesity, we studied transgenic mice with cardiac-specific overexpression of peroxisome proliferator–activated receptor γ 1 (PPARγ1) via the cardiac α-myosin heavy-chain promoter. The PPARγ transgenic mice develop abnormal accumulation of intracellular lipids and die as young adults before any significant reduction in systolic function. Using implantable ECG telemeters, we found that these mice have prolongation of the QRS and QT intervals and spontaneous ventricular arrhythmias, including polymorphic ventricular tachycardia and ventricular fibrillation. Isolated cardiomyocytes demonstrated prolonged action potential duration caused by reduced expression and function of the potassium channels responsible for repolarization. Short-term exposure to pioglitazone, a PPARγ agonist, had no effect on mortality or rhythm in WT mice but further exacerbated the arrhythmic phenotype and increased the mortality in the PPARγ transgenic mice. Conclusions— Our findings support an important link between PPARγ activation, cardiomyocyte lipid accumulation, ion channel remodeling, and increased cardiac mortality.

Septic shock results from bacterial infection and is associated with multi-organ failure, high mortality, and cardiac dysfunction. Sepsis causes both myocardial inflammation and energy depletion. We hypothesized that reduced cardiac energy production is a primary cause of ventricular dysfunction in sepsis. The JNK pathway is activated in sepsis and has also been implicated in impaired fatty acid oxidation in several tissues. Therefore, we tested whether JNK activation inhibits cardiac fatty acid oxidation and whether blocking JNK would restore fatty acid oxidation during LPS treatment. LPS treatment of C57BL/6 mice and adenovirus-mediated activation of the JNK pathway in cardiomyocytes inhibited peroxisome proliferator-activated receptor α expression and fatty acid oxidation. Surprisingly, none of the adaptive responses that have been described in other types of heart failure, such as increased glucose utilization, reduced αMHC:βMHC ratio or induction of certain microRNAs, occurred in LPS-treated mice. Treatment of C57BL/6 mice with a general JNK inhibitor (SP600125) increased fatty acid oxidation in mice and a cardiomyocyte-derived cell line. JNK inhibition also prevented LPS-mediated reduction in fatty acid oxidation and cardiac dysfunction. Inflammation was not alleviated in LPS-treated mice that received the JNK inhibitor. We conclude that activation of JNK signaling reduces fatty acid oxidation and prevents the peroxisome proliferator-activated receptor α down-regulation that occurs with LPS.

In the healthy adult human heart, 70% of the energy required for normal cellular function is derived from the uptake and oxidation of fatty acids, with the remainder being contributed by glucose, lactate and amino acids. Fatty acids are delivered to the heart either of two pathways: 1) free fatty acids (FFA) primarily originating in adipose tissue and associated with plasma albumin, and 2) fatty acids derived from lipoprotein lipase (LpL) mediated hydrolysis of lipoprotein triglycerides (TGs). The relative importance of each of these pathways in normal and pathological myocardial energy metabolism is unclear. Loss of the fatty acid uptake receptor CD36, which likely affects both sources of lipid uptake, leads to heart dysfunction in humans (1), but perhaps not in mice (2). In contrast, there are no reports of heart function in LpL deficient humans. It is possible that the heart either fully compensates for loss of LpL-derived fatty acids or that FFA, and not LpL mediated breakdown of lipoproteins, are the major source of heart energetic lipids. If this latter hypothesis were true, hearts from LpL-deficient humans would not need to alter their uptake of glucose. 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) scanning has been used to quantify myocardial blood flow and metabolism in the normal state and in patients with left ventricular hypertrophy, atherosclerosis and dilated cardiomyopathy. In this study, we used FDG-PET scanning to characterize myocardial glucose uptake in two patients with LpL deficiency and compared them against a healthy control subject and a patient with heart failure. Patient I was a 21-year-old female of French-Canadian descent with a history of a cholecystectomy and LpL deficiency. Her LpL deficiency was first documented during an episode of pancreatitis while on birth control pills and was confirmed by a reduction in post-heparin plasma LpL activity to less than 10% of normal. Her plasma TG level had been as high as 79.1 mmol/l (7000 mg/dl). Subsequently, she was treated with a fenofibrate and fish oil supplements. Three years later, with a plasma TG level of 33.1 mmol/l (3000 mg/dl), she suffered another episode of acute pancreatitis. Her diet and exercise were modified and she began to use medium chain TG oil. At the time of the FDG-PET study, her TG was 24.9 mmol/l (2205 mg/dl) and she had been pancreatitis free for more than a year. Patient II was a 52-year-old female whose LpL deficiency was confirmed in childhood by hypertriglyceridemia and reduced post-heparin plasma LpL activity. As a young adult she had two episodes of pancreatitis after being on birth control pills. Prior to her scan, fasting TG was 3.36 mmol/l (2957 mg/dl) while on dietary restrictions. The control patient was a healthy 52-year old male, while the patient with heart failure was a 55-year old male with non-ischemic cardiomyopathy. Both LpL deficient patients and the control subject had normal cardiac function and none of the patients had diabetes. In preparation for PET imaging, patients fasted overnight for at least 6 hours with baseline fasting blood glucose measured. For resting myocardial perfusion imaging, the patients received an intravenous bolus of 0.28 mCi/Kg of 13N-NH3 with a simultaneous 2-D dynamic acquisition protocol (10 sec/frame × 12, 30 sec/frame × 2, 180 sec/frame × 1). One hour later, patients were injected with 10 mCi of 18F-FDG and PET scanning began simultaneously, using a 2-D dynamic acquisition protocol over 60 minutes (10 sec/frame × 12, 30 sec/frame × 10, 120 sec/frame × 10, 300 sec/frame × 6). Heparin was not injected prior to the injection of 18F-FDG. Plasma glucose was measured 0, 15, 30 and 60 minutes after 18F-FDG injection. All images were corrected for scatter and measured photon attenuation. Image reconstruction was performed using iterative reconstruction and a Butterworth filter. It should be noted that the appearance of the relatively larger left ventricle volumes relative to wall thickness in the perfusion images for the control subject are due to differences in the zoom factor used during the acquisition of images and not due to the presence of a dilated cardiomyopathy. For quantitative analysis, the LV myocardium was divided into 5 regions of interest, (anterior, septal, apical, lateral and inferior). Time activity curves and input functions were generated for each region of interest and for the blood pool by placing a small region of interest within the basal LV blood pool on the mid-ventricular slice. A two compartment kinetic model was used to calculate myocardial blood flow in each region of interest using 13N-NH3. Patlak analysis was used to calculate the rate of myocardial glucose uptake (MGU) from 18F-FDG time activity curves for each region of interest, and globally for the LV. Mean MGU for the entire myocardium was calculated by averaging MGU values for all regions of interest. Prior to FDG administration, fasting plasma glucose for patient I was 5.3 mmol/l (96 mg/dl) and for patient II was 5.6 mmol/l (102 mg/dl). FDG-PET scan from patient I revealed resting myocardial perfusion that was qualitatively (Figure 1a top row) and quantifiably normal (Table 1). FDG uptake was also clearly visible (Figure 1a bottom row) and quantifiable (Table 2), demonstrating a diffuse and marked increase in non-insulin stimulated FDG uptake in all myocardial segments compared to the control subject (Figure 1c). Mean MGU was 9-fold higher than control (Figure 1a), with the greatest MGU seen in the basal-lateral segments of the myocardium. FDG-PET images from patient II, secondary to mis-registration from patient motion, demonstrated a perfusion defect in the anterior and lateral walls of the myocardium with a similar reduction in FDG uptake in these regions. However, mean MGU in patient II (Figure 1b) was 7.2 fold higher than control, with MGU being greatest in the distal-anterior segments (Table 2). This increased FDG uptake by the hearts of LpL deficient patients was substantially greater than that seen in the patient with heart failure (Figure 1d), where MGU was more focal and patchy, demonstrating a 1.75 fold increase in the basal-anterior segments of the myocardium (Table 2), with a fasting plasma glucose of 9.2 mmol/l (94 mg/dl). Fig 1 FDG-PET resting myocardial metabolism images of the left ventricle. Short-axis views are provided for each patient. Top row contains 13N-NH3 resting perfusion images of the left ventricle. Bottom row, are 18F-FDG resting myocardial metabolism images of ... Table 1 Mean blood flow (MBF) Table 2 Myocardial glucose uptake (MGU) Our study demonstrates a marked and diffuse increase in cardiac glucose uptake in patients with LpL deficiency. The likely explanation for this is that the heart has compensated for loss of LpL-derived lipids as a source of energy by increasing glucose uptake and oxidation, implying that lipoprotein-derived fatty acids, and not just FFA, are a major source of cardiac energy. Animal models with heart-specific loss of LpL also demonstrate a marked increase in glucose uptake (3). Although heart failure patients have increased myocardial glucose uptake, our patients had normal heart function. Increased myocardial FDG uptake is a metabolic feature of other conditions, such as myocarditis (4), sarcoidosis (5), endocarditis (6), acute myocardial ischemia (7), chronic hibernating myocardium and recent myocardial ischemia with delayed recovery of fatty acid metabolism (i.e. ischemic memory) (8, 9). Therefore a marked increase in glucose uptake is not pathognomonic for any of these conditions. As we demonstrate here, LpL deficiency may be another possible explanation for increased myocardial glucose uptake as detected by PET scanning.

Diacylglycerol (DAG) acyl transferase 1 (Dgat1) knockout (−/−) mice are resistant to high-fat-induced obesity and insulin resistance, but the reasons are unclear. Dgat1−/− mice had reduced mRNA levels of all three Ppar genes and genes involved in fatty acid oxidation in the myocardium of Dgat1−/− mice. Although DGAT1 converts DAG to triglyceride (TG), tissue levels of DAG were not increased in Dgat1−/− mice. Hearts of chow-diet Dgat1−/− mice were larger than those of wild-type (WT) mice, but cardiac function was normal. Skeletal muscles from Dgat1−/− mice were also larger. Muscle hypertrophy factors phospho-AKT and phospho-mTOR were increased in Dgat1−/− cardiac and skeletal muscle. In contrast to muscle, liver from Dgat1−/− mice had no reduction in mRNA levels of genes mediating fatty acid oxidation. Glucose uptake was increased in cardiac and skeletal muscle in Dgat1−/− mice. Treatment with an inhibitor specific for DGAT1 led to similarly striking reductions in mRNA levels of genes mediating fatty acid oxidation in cardiac and skeletal muscle. These changes were reproduced in cultured myocytes with the DGAT1 inhibitor, which also blocked the increase in mRNA levels of Ppar genes and their targets induced by palmitic acid. Thus, loss of DGAT1 activity in muscles decreases mRNA levels of genes involved in lipid uptake and oxidation.

Normal hearts have increased contractility in response to catecholamines. Because several lipids activate PKCs, we hypothesized that excess cellular lipids would inhibit cardiomyocyte responsiveness to adrenergic stimuli. Cardiomyocytes treated with saturated free fatty acids, ceramide, and diacylglycerol had reduced cellular cAMP response to isoproterenol. This was associated with increased PKC activation and reduction of β-adrenergic receptor (β-AR) density. Pharmacological and genetic PKC inhibition prevented both palmitate-induced β-AR insensitivity and the accompanying reduction in cell surface β-ARs. Mice with excess lipid uptake due to either cardiac-specific overexpression of anchored lipoprotein lipase, PPARγ, or acyl-CoA synthetase-1 or high-fat diet showed reduced inotropic responsiveness to dobutamine. This was associated with activation of protein kinase C (PKC)α or PKCδ. Thus, several lipids that are increased in the setting of lipotoxicity can produce abnormalities in β-AR responsiveness. This can be attributed to PKC activation and reduced β-AR levels.

Mutations in SCO2, a protein required for the proper assembly and functioning of cytochrome c oxidase (COX; complex IV of the mitochondrial respiratory chain), cause a fatal infantile cardioencephalomyopathy with COX deficiency. We have generated mice harboring a Sco2 knock-out (KO) allele and a Sco2 knock-in (KI) allele expressing an E-->K mutation at position 129 (E129K), corresponding to the E140K mutation found in almost all human SCO2-mutated patients. Whereas homozygous KO mice were embryonic lethals, homozygous KI and compound heterozygous KI/KO mice were viable, but had muscle weakness; biochemically, they had respiratory chain deficiencies as well as complex IV assembly defects in multiple tissues. There was a concomitant reduction in mitochondrial copper content, but the total amount of copper in examined tissues was not reduced. These mouse models should be of use in further studies of Sco2 function, as well as in testing therapeutic approaches to treat the human disorder.

There is a great need for the development of therapeutic strategies that can target biomolecules to damaged myocardium. Necrosis of myocardium during a myocardial infarction (MI) is characterized by extracellular release of DNA, which can serve as a potential target for ischemic tissue. Hoechst, a histological stain that binds to double-stranded DNA can be conjugated to a variety of molecules. Insulin-like growth factor-1 (IGF-1), a small protein/polypeptide with a short circulating-half life is cardioprotective following MI but its clinical use is limited by poor delivery, as intra-myocardial injections have poor retention and chronic systemic presence has adverse side effects. Here, we present a novel delivery vehicle for IGF-1, via its conjugation to Hoechst for targeting infarcted tissue. Using a mouse model of ischemia-reperfusion, we demonstrate that intravenous delivery of Hoechst-IGF-1 results in activation of Akt, a downstream target of IGF-1 and protects from cardiac fibrosis and dysfunction following MI.

Hearts utilize fatty acids as a primary source of energy. The sources of those lipids include free fatty acids and lipoprotein triglycerides. Deletion of the primary triglyceride-hydrolyzing enzyme lipoprotein lipase (LPL) leads to cardiac dysfunction. Whether heart LPL-knockout (hLPL0) mice are compromised due a deficiency in energetic substrates is unknown. To test whether alternative sources of energy will prevent cardiac dysfunction in hLPL0 mice, two different models were used to supply nonlipid energy. 1) hLPL0 mice were crossed with mice transgenically expressing GLUT1 in cardiomyocytes to increase glucose uptake into the heart; this cross-corrected cardiac dysfunction, reduced cardiac hypertrophy, and increased myocardial ATP. 2) Mice were randomly assigned to a sedentary or training group (swimming) at 3 mo of age, which leads to increased skeletal muscle production of lactate. hLPL0 mice had greater expression of the lactate transporter monocarboxylate transporter-1 (MCT-1) and increased cardiac lactate uptake. Compared with hearts from sedentary hLPL0 mice, hearts from trained hLPL0 mice had adaptive hypertrophy and improved cardiac function. We conclude that defective energy intake and not the reduced uptake of fat-soluble vitamins or cholesterol is responsible for cardiac dysfunction in hLPL0 mice. In addition, our studies suggest that adaptations in cardiac metabolism contribute to the beneficial effects of exercise on the myocardium of patients with heart failure.

Background— Cardiac dysfunction with sepsis is associated with both inflammation and reduced fatty acid oxidation. We hypothesized that energy deprivation accounts for sepsis-related cardiac dysfunction. Methods and Results— Escherichia coli lipopolysaccharide (LPS) administered to C57BL/6 mice (wild type) induced cardiac dysfunction and reduced fatty acid oxidation and mRNA levels of peroxisome proliferator–activated receptor (PPAR)-α and its downstream targets within 6–8 hours. Transgenic mice in which cardiomyocyte-specific expression of PPARγ is driven by the α-myosin heavy chain promoter (αMHC-PPARγ) were protected from LPS-induced cardiac dysfunction. Despite a reduction in PPARα, fatty acid oxidation and associated genes were not decreased in hearts of LPS-treated αMHC-PPARγ mice. LPS treatment, however, continued to induce inflammation-related genes, such as interleukin-1α, interleukin-1β, interleukin-6, and tumor necrosis factor-α in hearts of αMHC-PPARγ mice. Treatment of wild-type mice with LPS and the PPARγ agonist, rosiglitazone, but not the PPARα agonist (WY-14643), increased fatty acid oxidation, prevented LPS-mediated reduction of mitochondria, and treated cardiac dysfunction, as well as it improved survival, despite continued increases in the expression of cardiac inflammatory markers. Conclusions— Activation of PPARγ in LPS-treated mice prevented cardiac dysfunction and mortality, despite development of cardiac inflammation and PPARα downregulation.

Fish oil (FO) supplementation may improve cardiac function in some patients with heart failure, especially those with diabetes. To determine why this occurs, we studied the effects of FO in mice with heart failure either due to transgenic expression of the lipid uptake protein acyl CoA synthetase 1 (ACS1) or overexpression of the transcription factor peroxisomal proliferator-activated receptor (PPAR) γ via the cardiac-specific myosin heavy chain (MHC) promoter. ACS1 mice and control littermates were fed 3 diets containing low-dose or high-dose FO or nonpurified diet (NPD) for 6 weeks. MHC-PPARγ mice were fed low-dose FO or NPD. Compared with control mice fed with NPD, ACS1, and MHC-PPARγ, mice fed with NPD had reduced cardiac function and survival with cardiac fibrosis. In contrast, ACS1 mice fed with high-dose FO had better cardiac function, survival, and less myocardial fibrosis. FO increased eicosapentaenoic and docosahexaenoic acids and reduced saturated fatty acids in cardiac diacylglycerols. This was associated with reduced protein kinase C alpha and beta activation. In contrast, low-dose FO reduced MHC-PPARγ mice survival with no change in protein kinase C activation or cardiac function. Thus, dietary FO reverses fibrosis and improves cardiac function and survival of ACS1 mice but does not benefit all forms of lipid-mediated cardiomyopathy.

We thank Haufe et al for their insightful comments on our study of adipose tissue inflammation and adiponectin resistance in patients with advanced heart failure (HF) and the impact of mechanical unloading.1 We appreciate the observation that incorrect homeostasis model of insulin resistance (HOMA-IR) values were listed in Table 3. Upon recalculation using the HOMA-IR formula, the correct values were found to be 1.0±0.6 for controls, 7.6±7.7 in advanced HF ( P =0.02 versus controls) and 4.5±3.6 after left ventricular assist device (LVAD) support ( P =0.01 versus HF). This supports the conclusion …

Septic cardiac dysfunction has been attributed to either inflammation or suppression of fatty acid oxidation (FAO). We hypothesized that energy deprivation accounts for cardiac dysfunction in lipopolysaccharide (LPS)-induced sepsis. LPS compromised cardiac function, increased cardiac inflammatory markers (interleukin (IL)-1α, IL-6 and tumor necrosis factor (TNF)α) mRNA, and reduced FAO, ATP and FAO-related gene expression: Peroxisome proliferator activating receptor (PPAR)α, cluster of differentiation 36, lipoprotein lipase (LpL), fatty acid transport protein, carnitine palmitoyl-transferase (Cpt)1, PPARγ coactivator (PGC-1)α and PGC-1β in C57BL/6 mice. LC-MS/MS analysis of cardiac lipids showed that total ceramide, which might account for defective FAO and ceramide species were not modulated by LPS. Electron microscopy and ATPase6 DNA levels showed that LPS-treated animals had fewer and smaller cardiac mitochondria. PPARα agonist, WY-14643, did not prevent cardiac dysfunction and suppression of FAO-associated gene expression in LPS-treated mice. In contrast, LPS did not affect cardiac function of mice with cardiomyocyte-specific expression of PPARγ (αMHC-PPARg), although cardiac IL-1α, IL-6 and TNFα mRNA levels were increased. Despite a 77% reduction in PPARα, mRNA levels of FAO-associated genes, such as acyl-CoA oxidase, PGC-1α, PPARδ, Cpt1 increased over 10-fold as compared to saline-treated αMHC-PPARg mice. Similarly, cardiac FAO and ATP content was 2.6 and 5-fold greater in LPS-treated αMHC-PPARγ mice compared to LPS-treated C57BL/6 mice. Moreover, treatment of C57BL/6 mice with LPS and the PPARγ agonist, rosiglitazone, prevented cardiac dysfunction, increased FAO and relevant gene expression, while IL-1α, IL-6 and TNFα mRNA levels increased. Rosiglitazone prevented LPS-mediated reduction of PGC-1α and maintained the number and size of mitochondria. Treatment of C57BL/6 mice with a lethal dose of LPS (15 mg/kg) and repeated doses of rosiglitazone (30mg/kg/day for 72 hours) improved survival, mobility and overall appearance of LPS-treated mice. Thus, PPARγ activation stabilized cardiac energy and prevented cardiac dysfunction and mortality in septic animals despite cardiac inflammation and PPARα downregulation.

During acute myocardial infarction (MI) there is excessive necrosis of myocardial cells, leading to the release of large amounts of DNA, representing a potential target for drug delivery. Hoechst, a commonly used molecule for staining nuclei, binds to the minor groove of double-stranded DNA and can be functionalized to contain reactive groups such as free amines, sulfhydryls, and biotin moieties. Insulin-like growth factor-1 (IGF-1), a small molecule with a short half-life is protective immediately following MI, though there is potential for long-term toxicity and off-target effects. Therefore, we hypothesized that conjugating IGF-1 to Hoechst would increase targeting of IGF-1 to the injured myocardium. Hoechst-IGF1 (H-IGF1) was synthesized by binding Hoechst-biotin to biotinylated IGF-1 via a fluorescent streptavidin linker. Intact cells did not show nuclear staining with H-IGF1, while permeabilized cells had a significant increase in blue fluorescent Hoechst staining, indicating H-IGF1 was cell impermeable but could still bind DNA. Activity of H-IGF1 was demonstrated by Akt phosphorylation in cultured cardiac progenitor cells and was similar to native IGF-1. To determine in-vivo targeting of H-IGF1 to MI, mice underwent 30 minutes of coronary artery ligation followed by reperfusion (I/R). Six hours following MI, mice were injected intravenously with 70ng of H-IGF1, S-IGF1 (streptavidin bound IGF-1 only) or PBS followed by in vivo imaging at 30 and 120 minutes post-injection. At 30 minutes post-injection, we found 3.2% (2.2 of 70ng) of the injected dose of H-IGF1 in infarcted hearts compared with 1.8% (1.3 of 70ng) of S-IGF1 (n=5-7; p

BACKGROUND Chronic heart failure is associated with higher risk for developing diabetes mellitus. Secretory products from adipocytes may contribute to the deterioration in glycemic control and increased insulin resistance (IR). Retinol binding protein 4 (RBP4) is an adipose tissue-derived protein with pro-diabetogenic effects. The aim of the present study was to investigate the relationship of RBP4 in patients with heart failure. METHODS AND RESULTS Serum levels of RBP4, insulin, and fasting glucose were assessed in 58 patients with severe heart failure at the time of left ventricular assist device (LVAD) implantation and in 44 patients at the time of explantation, as well as in 10 normal control subjects. Serum RBP4 levels were measured by specific enzyme-linked immunosorbent assay, and IR was assessed using the homeostatic model of IR (HOMA-IR). Fasting glucose, insulin and HOMA-IR were significantly higher in patients at the time of LVAD implantation compared to controls (all P

Background— Heart failure (HF) is characterized by inflammation, insulin resistance, and progressive catabolism. We hypothesized that patients with advanced HF also develop adipose tissue inflammation associated with impaired adipokine signaling and that hemodynamic correction through implantation of ventricular assist devices (VADs) would reverse adipocyte activation and correct adipokine signaling in advanced HF. Methods and Results— Circulating insulin, adiponectin, leptin, and resistin levels were measured in 36 patients with advanced HF before and after VAD implantation and 10 healthy control subjects. Serum adiponectin was higher in HF patients before VAD implantation compared with control subjects (13.3±4.9 versus 6.4±2.1 μg/mL, P =0.02). VAD implantation (mean, 129±99 days) reduced serum adiponectin (7.4±3.4 μg/mL, P P P 2 versus 5583±142 μm 2 in control subjects; P P Conclusions— Adipose tissue inflammation and adiponectin resistance develop in advanced HF. Mechanical unloading of the failing myocardium reverses adipose tissue macrophage infiltration, inflammation, and adiponectin resistance in patients with advanced HF.

Purpose of review Diseases associated with ectopic disposition of lipids are becoming an increasingly important medical problem as the incidence of type 2 diabetes and obesity increases. One of the organs affected by lipotoxicity is the heart and this review presents an update on human and animal studies of this problem. Recent findings Human studies have clearly correlated heart dysfunction with the content of triglyceride. More recently human heart samples have been used to assess gene changes associated with altered lipid accumulation. Genetically altered mice have been created that develop lipotoxic cardiomyopathies and newer investigations are attempting to delineate curative therapies. Summary Human studies will confirm the metabolic changes associated with lipotoxic cardiomyopathy and, hopefully, animal studies will guide treatment options.

Left ventricular apical ballooning is an increasingly reported phenomenon with an onset that is usually triggered by severe and often acute emotional incidents. We report a rare case of acute left ventricular apical ballooning syndrome, mimicking acute ST-elevation myocardial infarction, in a post menopausal woman whose only predisposing factor was an all-night cocaine binge.

Aldose reductase (AR), an enzyme mediating the first step in the polyol pathway of glucose metabolism, is associated with complications of diabetes mellitus and increased cardiac ischemic injury. We investigated whether deleterious effects of AR are due to its actions specifically in cardiomyocytes. We created mice with cardiac specific expression of human AR (hAR) using the α-myosin heavy chain (MHC) promoter and studied these animals during aging and with reduced fatty acid (FA) oxidation. hAR transgenic expression did not alter cardiac function or glucose and FA oxidation gene expression in young mice. However, cardiac overexpression of hAR caused cardiac dysfunction in older mice. We then assessed whether hAR altered heart function during ischemia reperfusion. hAR transgenic mice had greater infarct area and reduced functional recovery than non-transgenic littermates. When the hAR transgene was crossed onto the PPAR alpha knockout background, another example of greater heart glucose oxidation, hAR expressing mice had increased heart fructose content, cardiac fibrosis, ROS, and apoptosis. In conclusion, overexpression of hAR in cardiomyocytes leads to cardiac dysfunction with aging and in the setting of reduced FA and increased glucose metabolism. These results suggest that pharmacological inhibition of AR will be beneficial during ischemia and in some forms of heart failure.

Increased Levels of Retinol Binding Protein 4 in Patients with Severe Heart Failure Correct after Hemodynamic Improvement through Ventricular Assist Device Placement N. Chavarria, F.H. Cheema, R. Khan, A. Chokshi, E. Collado, T. Kato, H. Takayama, Y. Naka, M. Farr, D.M. Mancini, P.C. Schulze. Cardiology/Medicine, Columbia University Medical Center, New York, NY; Cardiothoracic Surgery, Columbia University Medical Center, New York, NY.