Intramyocardial Lipid Research Articles

Abstract Mo102: Swine Model of Heart Failure with Preserved Ejection Fraction Driven by Lipoprotein Lipase Inhibition and Enhanced Cardiac Low-Density Lipoprotein Receptor Expression

Background: Heart failure with preserved ejection fraction (HFpEF) poses an escalating public health threat, marked by growing incidence and high mortality. In the cardiometabolic phenogroup of HFpEF that includes diabetes and obesity, intramyocardial lipid content is a prognostic indicator of diastolic dysfunction and adverse outcome. Our group recently reported a mouse model of cardiometabolic HFpEF wherein myocardial lipotoxicity was induced by systemic inhibition of lipoprotein lipase (LPL) with Poloxamer 407 (P407) and cardiac overexpression of the LDL receptor (LDLR), conditions that have been documented in clinical HFpEF. The model demonstrates myocardial lipid accumulation, fibrosis, arrhythmia, and diastolic dysfunction. To reproduce this model in large animals we implemented the same protocol in pigs. Methods: Female Yorkshire swine (~25 Kg) were subjected to one of two protocols including: 1) single intracoronary (i.c.) injection of 10 13 AAV9-cTnT-LDLR particles and biweekly intraperitoneal (i.p.) P407 at 1g/Kg, (high dose, n=2), or 2) Double i.c. injections of 10 13 AAV9-cTnT-LDLR particles and biweekly i.p. P407 at 0.25g/Kg) (low dose, n=2). Cardiac structure and function were evaluated by MRI, and hemodynamics measured by PV-Loop at baseline, 4, 8, and 12 weeks. Blood was collected biweekly for complete blood count (CBC), basic biochemistry, and liver and lipid panels. Tissues were collected for protein and histopathological analysis. Results: In both strategies, the animals developed high LDL-cholesterol and cardiac hypertrophy with preserved EF. High dose P407 led to higher triglycerides, VLDL, HDL, liver injury (ALT > 200U/L), and steatosis at 4 weeks. One of the 2 pigs died at 3 weeks. Low dose P407 and high dose viral particles induced HFpEF at ~12 weeks with increased LV mass, relative wall thickness, end-diastolic pressure, and tau. Serum LDL-C accumulated from an initial value of 161 to 344.5mg/dL at 12 weeks. No significant liver injury was present until week 12 (ALT<88 U/L, AST<59 U/L). Both strategies did not exhibit abnormalities in CBC or other biochemical parameters. Conclusions: Low dose inhibition of LPL combined with cardiac overexpression of LDLR confers HFpEF in swine.

Fructose aggravates copper-deficiency-induced cardiac remodeling by inhibiting SERCA2a.

Accumulating evidence demonstrates that copper deficiency (CuD) is a risk factor for cardiovascular diseases, besides, fructose has been strongly linked to the development of cardiovascular diseases. However, how CuD or fructose causes cardiovascular diseases is not clearly delineated. The present study aims to investigate the mechanism of CuD or fructose on cardiac remodeling. We established a model of CuD- or fructose-induced cardiac hypertrophy in 3-week-old male Sprague-Dawley (SD) rats by CuD diet supplemented with or without 30% fructose for 4 weeks. In vitro study was performed by treating cardiomyocytes with tetrathiomolydbate (TM) and fructose. Echocardiography, histology analysis, immunofluorescence, western blotting, and qPCR were performed. Our findings revealed that CuD caused noticeable cardiac hypertrophy either in the presence or absence of fructose supplement. Fructose exacerbated CuD-induced cardiac remodeling and intramyocardial lipid accumulation. Furthermore, we presented that the inhibition of autophagic flux caused by Ca2+ disturbance is the key mechanism by which CuD- or fructose-induced cardiac remodeling. The reduced expression of sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2a (SERCA2a) in cardiomyocytes accounts for the elevated cytoplasmic Ca2+ concentration. Collectively, our study suggested that fructose aggravated CuD-induced cardiac remodeling through the blockade of autophagic flux via SERCA2a decreasing-induced Ca2+ imbalance.

Ironing out the details: ferroptosis and its relevance to diabetic cardiomyopathy.

Ferroptosis is a newly identified myocardial cell death mechanism driven by iron-dependent lipid peroxidation. The presence of elevated intramyocardial lipid levels and excessive iron in patients with diabetes suggest a predominant role of ferroptosis in diabetic cardiomyopathy. As myocardial cell death is a precursor of heart failure, and intensive glycemic control cannot abate the increased risk of heart failure in patients with diabetes, targeting myocardial cell death via ferroptosis is a promising therapeutic avenue to prevent and/or treat diabetic cardiomyopathy. This review provides updated and comprehensive molecular mechanisms underpinning ferroptosis, clarifies several misconceptions about ferroptosis, emphasizes the importance of ferroptosis in diabetes-induced myocardial cell death, and offers valuable approaches to evaluate and target ferroptosis in the diabetic heart. Furthermore, basic concepts and ideas presented in this review, including glutathione peroxidase-4-independent and mitochondrial mechanisms of ferroptosis, are also important for investigating ferroptosis in other diabetic organs, as well as nondiabetic and metabolically compromised hearts.

Treatment with recombinant Sirt1 rewires the cardiac lipidome and rescues diabetes-related metabolic cardiomyopathy.

Metabolic cardiomyopathy (MCM), characterized by intramyocardial lipid accumulation, drives the progression to heart failure with preserved ejection fraction (HFpEF). Although evidence suggests that the mammalian silent information regulator 1 (Sirt1) orchestrates myocardial lipid metabolism, it is unknown whether its exogenous administration could avoid MCM onset. We investigated whether chronic treatment with recombinant Sirt1 (rSirt1) could halt MCM progression. db/db mice, an established model of MCM, were supplemented with intraperitoneal rSirt1 or vehicle for 4weeks and compared with their db/ + heterozygous littermates. At the end of treatment, cardiac function was assessed by cardiac ultrasound and left ventricular samples were collected and processed for molecular analysis. Transcriptional changes were evaluated using a custom PCR array. Lipidomic analysis was performed by mass spectrometry. H9c2 cardiomyocytes exposed to hyperglycaemia and treated with rSirt1 were used as in vitro model of MCM to investigate the ability of rSirt1 to directly target cardiomyocytes and modulate malondialdehyde levels and caspase 3 activity. Myocardial samples from diabetic and nondiabetic patients were analysed to explore Sirt1 expression levels and signaling pathways. rSirt1 treatment restored cardiac Sirt1 levels and preserved cardiac performance by improving left ventricular ejection fraction, fractional shortening and diastolic function (E/A ratio). In left ventricular samples from rSirt1-treated db/db mice, rSirt1 modulated the cardiac lipidome: medium and long-chain triacylglycerols, long-chain triacylglycerols, and triacylglycerols containing only saturated fatty acids were reduced, while those containing docosahexaenoic acid were increased. Mechanistically, several genes involved in lipid trafficking, metabolism and inflammation, such as Cd36, Acox3, Pparg, Ncoa3, and Ppara were downregulated by rSirt1 both in vitro and in vivo. In humans, reduced cardiac expression levels of Sirt1 were associated with higher intramyocardial triacylglycerols and PPARG-related genes. In the db/db mouse model of MCM, chronic exogenous rSirt1 supplementation rescued cardiac function. This was associated with a modulation of the myocardial lipidome and a downregulation of genes involved in lipid metabolism, trafficking, inflammation, and PPARG signaling. These findings were confirmed in the human diabetic myocardium. Treatments that increase Sirt1 levels may represent a promising strategy to prevent myocardial lipid abnormalities and MCM development.

700 EPICARDIAL ADIPOSE TISSUE AND ATRIAL FIBRILLATION, A REVIEW

Abstract Aims Atrial fibrillation (AF) is the most common cardiac arrhythmia closely associated with stroke, heart failure, and decreased quality of life. Excess adiposity has long been associated with increased cardiovascular disease and risk factor of AF. Methods Epicardial Adipose Tissue (EAT) is the fat depot located between the myocardium and the epicardium supplied by branches of the coronary arteries. By contrast, pericardial adipose tissue (PAT) is located externally and is supplied by non-​coronary arteries. EAT fat thickness was first visualized by and measured with Transthoracic Two-dimensional (2D) Echocardiography because is visible as an echo free space between the outer wall of the myocardium and the visceral layer of the pericardium. Moreover, computed tomography (CT) has been used to measure EAT through accurate volumetric measurement. CMR imaging is instead considered the ‘gold standard’ modality for imaging adipose tissue.EAT function and morphology in normal conditions is protective but it function changes under pathological conditions.Lots of studies, infact, indicated higher pericardial fat volume was associated with a nearly 40% higher odds of prevalent AF, and the association remained significant even after adjustment for other AF risk factors including age, sex, myocardial infarction, heart failure, BMI, and other regional fat deposits. Infact, EAT volume is related to impaired diastolic function, elevated left ventricular mass, and enlarged left atrium. Moreover, a higher degree of EAT accumulation is often observed in patients with systematic inflammatory disease and oxidative stress, such as rheumatoid arthritis and psoriasis, compared with those without systematic inflammatory disease even after adjusting other risk factors. Free fatty acids can be transported from EAT to the myocardium and lead to electromechanical changes in atrial tissue: they separate cardiomyocytes and this situation result in conduction slowing, loss of side-​to-​side cell connections and myocardial disorganization that leads to conduction delay and re-​entry. Results EAT is a modifiable cardiovascular risk factor and a potential novel therapeutic target owing to its responsiveness to drugs with pleiotropic effects such as GLP1R agonists (visceral fat reduction is one of the non-​glycaemic effects of the GLP1R agonists), SGLT2 inhibitors (reduction of intramyocardial lipid content by increasing EAT lipolysis and ketone body oxidation) and statins (reduction of EAT thickness through modulation of peroxisome proliferator-​activated receptors (PPARs)). Furthemore, suppression of AF after injecting botulinum toxin into EAT in patients with paroxysmal AF, both during postoperative cardiac surgery and catheter ablation of epicardial fat pad can also result in EAT reduction. Conclusion EAT is a measurable and modifiable cardiovascular risk factor that adds qualitative value to the stratification of cardiovascular risk. In the context of atrial fibrillation, EAT represents a new pathogenic substrate through the regional secretion of factors that induce fibrosis and neurohormonal disarray of the atrial myocytes. Genetic studies are also optional to uncover pathophysiological mechanism of EAT-AF interaction and clarify causal relationship. Finally, more efforts should be made to realize application of EAT quantification in risk evaluation and management for AF.

La cardiomyopathie du Cushing – Cardiac fat in Cushing's syndrome

Cardiovascular disease is the leading cause of death in patients with Cushing's syndrome. Cortisol excess predisposes to well-established cardiovascular risk factors, including hypertension, visceral obesity, dyslipidemia and glucose intolerance, but also exerts direct effects on cardiac structure and function. Increased ventricular mass and subclinical ventricular dysfunction, both potentially reversible after treatment, have been reported in patients with Cushing's syndrome. This increase in ventricular mass contrasts with skeletal muscle atrophy and sarcopenia related to protein wasting induced by hypercortisolism. Cardiac fat might play an important role in the pathogenesis of Cushing's syndrome associated cardiomyopathy. However, in contrast to the general population, in which visceral obesity and diabetes is associated with cardiac steatosis, no increase in intramyocardial lipid content could be found in patients with Cushing's syndrome. Cortisol excess might stimulate beta oxidation and triglyceride consumption and therefore could “protect” cardiomyocytes from ectopic lipid deposition. On the other hand, an accumulation of epicardial and pericardial fat has been observed in Cushing's syndrome. Whereas pericardial fat reflects the thoracic visceral adipose tissue, epicardial fat might be highly susceptible to cortisol, as it decreased following biochemical disease remission in short term follow up. Epicardial fat is directly mixed with the myocardium without being separated by any fascia and shares the same blood supply. It therefore directly exerts paracrine actions on the myocardium and is well known to promote inflammation, microvascular dysfunction and fibrosis. Epicardial fat could play a major role in the pathogenesis of Cushing's syndrome associated cardiomyopathy.

Epicardial and Pericardial Adiposity Without Myocardial Steatosis in Cushing Syndrome

Cardiovascular disease is the leading cause of death in patients with Cushing syndrome. Cortisol excess and adverse metabolic profile could increase cardiac fat, which can subsequently impair cardiac structure and function. We aimed to evaluate cardiac fat mass and distribution in patients with Cushing syndrome. In this prospective, cross-sectional study, 23 patients with Cushing syndrome and 27 control individuals of comparable age, sex, and body mass index were investigated by cardiac magnetic resonance imaging and proton spectroscopy. Patients were explored before and after biochemical disease remission. Myocardial fat measured by the Dixon method was the main outcome measure. The intramyocardial triglyceride/water ratio measured by spectroscopy and epicardial and pericardial fat volumes were secondary outcome measures. No difference was found between patients and controls in intramyocardial lipid content. Epicardial fat mass was increased in patients compared to controls (30.8 g/m2 [20.4-34.8] vs 17.2 g/m2 [13.1-23.5], P < .001). Similarly, pericardial fat mass was increased in patients compared to controls (28.3 g/m2 [17.9-38.0] vs 11.4 g/m2 [7.5-19.4], P = .003). Sex, glycated hemoglobin A1c, and the presence of hypercortisolism were independent determinants of epicardial fat. Pericardial fat was associated with sex, impaired glucose homeostasis and left ventricular wall thickness. Disease remission decreased epicardial fat mass without affecting pericardial fat. Intramyocardial fat stores are not increased in patients with Cushing syndrome, despite highly prevalent metabolic syndrome, suggesting increased cortisol-mediated lipid consumption. Cushing syndrome is associated with marked accumulation of epicardial and pericardial fat. Epicardial adiposity may exert paracrine proinflammatory effects promoting cardiomyopathy.

Human left ventricle transcriptome signatures and signalling pathways in patients with high and low intramyocardial lipid

Background and Aims: The aim of this study was to determine transcriptomic signatures and signalling pathways in human left ventricular myocardium (LV) with low or high intramyocellular (IMCL) lipid content.

Nootkatone, a Dietary Fragrant Bioactive Compound, Attenuates Dyslipidemia and Intramyocardial Lipid Accumulation and Favorably Alters Lipid Metabolism in a Rat Model of Myocardial Injury: An In Vivo and In Vitro Study.

In the present study, we assessed whether nootkatone (NKT), a sesquiterpene in edible plants, can provide protection against dyslipidemia, intramyocardial lipid accumulation, and altered lipid metabolism in a rat model of myocardial infarction (MI) induced by subcutaneous injections of isoproterenol (ISO, 85 mg/kg) on days 9 and 10. The rats were pre- and co-treated with NKT (10 mg/kg, p.o.) administered daily for 11 days. A significant reduction in the activities of myocardial creatine kinase and lactate dehydrogenase, as well as non-enzymatic antioxidants, and alterations in lipids and lipoproteins, along with a rise in plasma lipid peroxidation and intramyocardial lipid accumulation, were observed in ISO-treated rats. ISO administration induced alterations in the activities of enzymes/expressions that played a significant role in altering lipid metabolism. However, NKT treatment favorably modulated all biochemical and molecular parameters altered by ISO and showed protective effects against oxidative stress, dyslipidemia, and altered lipid metabolism, attributed to its free-radical-scavenging and antihyperlipidemic activities in rats with ISO-induced MI. Additionally, NKT decreased the accumulation of lipids in the myocardium as evidenced from Oil red O staining. Furthermore, the in vitro observations demonstrate the potent antioxidant property of NKT. The present study findings are suggestive of the protective effects of NKT on dyslipidemia and the underlying mechanisms. Based on our findings, it can be suggested that NKT or plants rich in NKT can be promising for use as a phytopharmaceutical or nutraceutical in protecting the heart and correcting lipid abnormalities and dyslipidemia, which are risk factors for ischemic heart diseases.

Cardiomyopathy in obesity, insulin resistance and diabetes.

The prevalence of obesity, insulin resistance and diabetes is increasing rapidly. Most patients with these disorders have hypertriglyceridaemia and increased plasma levels of fatty acids, which are taken up and stored in lipid droplets in the heart. Intramyocardial lipids that exceed the capacity for storage and oxidation can be lipotoxic and induce non-ischaemic and non-hypertensive cardiomyopathy, termed diabetic or lipotoxic cardiomyopathy. The clinical features of diabetic cardiomyopathy are cardiac hypertrophy and diastolic dysfunction, which lead to heart failure, especially heart failure with preserved ejection fraction. Although the pathogenesis of the cardiomyopathy is multifactorial, diabetic dyslipidaemia and intramyocardial lipid accumulation are the key pathological features, triggering cellular signalling and modifications of proteins and lipids via generation of toxic metabolic intermediates. Most clinical studies have shown no beneficial effect of anti-diabetic agents and statins on outcomes in heart failure patients without atherosclerotic diseases, indicating the importance of identifying underlying mechanisms and early interventions for diabetic cardiomyopathy. Here, we summarize the molecular mechanisms of diabetic cardiomyopathy, with a special emphasis on cardiac lipotoxicity, and discuss the role of peroxisome proliferator-activated receptor α and dysregulated fatty acid metabolism as potential therapeutic targets.

Acute intramyocardial lipid accumulation in rats does not slow cardiac conduction per se.

Diabetic patients suffer from both cardiac lipid accumulation and an increased risk of arrhythmias and sudden cardiac death. This correlation suggests a link between diabetes induced cardiac steatosis and electrical abnormalities, however, the underlying mechanism remains unknown. We previously showed that cardiac conduction velocity slows in Zucker diabetic fatty rats and in fructose‐fat fed rats, models that both exhibit prominent cardiac steatosis. The aim of this study was to investigate whether acute cardiac lipid accumulation reduces conduction velocity per se. Cardiac lipid accumulation was induced acutely by perfusing isolated rat hearts with palmitate‐glucose buffer, or subacutely by fasting rats overnight. Subsequently, longitudinal cardiac conduction velocity was measured in right ventricular tissue strips, and intramyocardial triglyceride and lipid droplet content was determined by thin layer chromatography and BODIPY staining, respectively. Perfusion with palmitate‐glucose buffer significantly increased intramyocardial triglyceride levels compared to perfusion with glucose (2.16 ± 0.17 (n = 10) vs. 0.92 ± 0.33 nmol/mg WW (n = 9), P < 0.01), but the number of lipid droplets was very low in both groups. Fasting of rats, however, resulted in both significantly elevated intramyocardial triglyceride levels compared to fed rats (3.27 ± 0.43 (n = 10) vs. 1.45 ± 0.24 nmol/mg WW (n = 10)), as well as a larger volume of lipid droplets (0.60 ± 0.13 (n = 10) vs. 0.21 ± 0.06% (n = 10), P < 0.05). There was no significant difference in longitudinal conduction velocity between palmitate‐glucose perfused and control hearts (0.77 ± 0.025 (n = 10) vs. 0.75 m/sec ± 0.029 (n = 9)), or between fed and fasted rats (0.75 ± 0.042 m/sec (n = 10) vs. 0.79 ± 0.047 (n = 10)). In conclusion, intramyocardial lipid accumulation does not slow cardiac longitudinal conduction velocity per se. This is true for both increased intramyocardial triglyceride content, induced by palmitate‐glucose perfusion, and increased intramyocardial triglyceride and lipid droplet content, generated by fasting.

Preservation of Acyl Coenzyme A Attenuates Pathological and Metabolic Cardiac Remodeling Through Selective Lipid Trafficking.

Metabolic remodeling in heart failure contributes to dysfunctional lipid trafficking and lipotoxicity. Acyl coenzyme A synthetase-1 (ACSL1) facilitates long-chain fatty acid (LCFA) uptake and activation with coenzyme A (CoA), mediating the fate of LCFA. The authors tested whether cardiac ACSL1 overexpression aids LCFA oxidation and reduces lipotoxicity under pathological stress of transverse aortic constriction (TAC). Mice with cardiac restricted ACSL1 overexpression (MHC-ACSL1) underwent TAC or sham surgery followed by serial in vivo echocardiography for 14 weeks. At the decompensated stage of hypertrophy, isolated hearts were perfused with 13C LCFA during dynamic-mode 13C nuclear magnetic resonance followed by in vitro nuclear magnetic resonance and mass spectrometry analysis to assess intramyocardial lipid trafficking. In parallel, acyl CoA was measured in tissue obtained from heart failure patients pre- and postleft ventricular device implantation plus matched controls. TAC-induced cardiac hypertrophy and dysfunction was mitigated in MHC-ACSL1 hearts compared with nontransgenic hearts. At 14 weeks, TAC increased heart weight to tibia length by 46% in nontransgenic mice, but only 26% in MHC-ACSL1 mice, whereas ACSL1 mice retained greater ejection fraction (ACSL1 TAC: 65.8±7.5%; nontransgenic TAC: 45.9±7.3) and improvement in diastolic E/E'. Functional improvements were mediated by ACSL1 changes to cardiac LCFA trafficking. ACSL1 accelerated LCFA uptake, preventing C16 acyl CoA loss post-TAC. Long-chain acyl CoA was similarly reduced in human failing myocardium and restored to control levels by mechanical unloading. ACSL1 trafficked LCFA into ceramides without normalizing the reduced triglyceride storage in TAC. ACSL1 prevented de novo synthesis of cardiotoxic C16- and C24-, and C24:1 ceramides and increased potentially cardioprotective C20- and C22-ceramides post-TAC. ACLS1 overexpression activated AMP activated protein kinase at baseline, but during TAC, prevented the reduced LCFA oxidation in hypertrophic hearts and normalized energy state (phosphocreatine:ATP) and consequently, AMP activated protein kinase activation. This is the first demonstration of reduced acyl CoA in failing hearts of humans and mice, and suggests possible mechanisms for maintaining mitochondrial oxidative energy metabolism by restoring long-chain acyl CoA through ASCL1 activation and mechanical unloading. By mitigating cardiac lipotoxicity, via redirected LCFA trafficking to ceramides, and restoring acyl CoA, ACSL1 delayed progressive cardiac remodeling and failure.

Soluble Receptor for Advanced Glycation End Products: A Protective Molecule against Intramyocardial Lipid Accumulation in Obese Zucker Rats?

Most of the obesity-related complications are due to ectopic fat accumulation. Recently, the activation of the cell-surface receptor for advanced glycation end products (RAGE) has been associated with lipid accumulation in different organs. Nevertheless, the role of RAGE and sRAGE, the soluble form that prevents ligands to activate RAGE, in intramyocardial lipid accumulation is presently unknown. To this aim, we analyzed whether, in obesity, intramyocardial lipid accumulation and lipid metabolism-related transcriptome are related to RAGE and sRAGE. Heart and serum samples were collected from 10 lean (L) and 10 obese (OB) Zucker rats. Oil red staining was used to detect lipids on frozen heart sections. The lipid metabolism-related transcriptome (84 genes) was analyzed by a specific PCR array. Heart RAGE expression was explored by real-time RT-PCR and Western blot analyses. Serum levels of sRAGE (total and endogenous secretory form (esRAGE)) were quantified by ELISA. Genes promoting fatty acid transport, activation, and oxidation in mitochondria/peroxisomes were upregulated in OB hearts. Intramyocardial lipid content did not differ between OB and L rats, as well as RAGE expression. A slight increase in epicardial adipose tissue was observed in OB hearts. Total sRAGE and esRAGE concentrations were significantly higher in OB rats. sRAGE may protect against obesity-induced intramyocardial lipid accumulation by preventing RAGE hyperexpression, therefore allowing lipids to be metabolized. EAT also played a protective role by working as a buffering system that protects the myocardium against exposure to excessively high levels of fatty acids. These observations reinforce the potential role of RAGE pathway as an interesting therapeutic target for obesity-related complications, at least at the cardiovascular level.

1431Modulation of JunD by miR-494-3p causes intra-myocardial lipid accumulation and obesity cardiomyopathy: a study in mice and humans

1431Modulation of JunD by miR-494-3p causes intra-myocardial lipid accumulation and obesity cardiomyopathy: a study in mice and humans

Dietary soya protein improves intra-myocardial lipid deposition and altered glucose metabolism in a hypertensive, dyslipidaemic, insulin-resistant rat model.

This study investigates the effects of replacing dietary casein by soya protein on the underlying mechanisms involved in the impaired metabolic fate of glucose and lipid metabolisms in the heart of dyslipidaemic rats chronically fed (8 months) a sucrose-rich (62·5 %) diet (SRD). To test this hypothesis, Wistar rats were fed an SRD for 4 months. From months 4 to 8, half the animals continued with the SRD and the other half were fed an SRD in which casein was substituted by soya. The control group received a diet with maize starch as the carbohydrate source. Compared with the SRD-fed group, the following results were obtained. First, soya protein significantly (P<0·001) reduced the plasma NEFA levels and normalised dyslipidaemia and glucose homoeostasis, improving insulin resistance. The protein levels of fatty acid translocase at basal state and under insulin stimulation and the protein levels and activity of muscle-type carnitine palmitoyltransferase 1 were normalised. Second, a significant (P<0·001) reduction of TAG, long-chain acyl CoA and diacylglycerol levels was observed in the heart muscle. Third, soya protein significantly increased (P<0·01) GLUT4 protein level under insulin stimulation and normalised glucose phosphorylation and oxidation. A reduction of phosphorylated AMP protein kinase protein level was recorded without changes in uncoupling protein 2 and PPARα. Fourth, hydroxyproline concentration decreased in the left ventricle and hypertension was normalised. The new information provided shows the beneficial effects of soya protein upon the altered pathways of glucose and lipid metabolism in the heart muscle of this rat model.

The effects of chronic FAAH inhibition on myocardial lipid metabolism in normotensive and DOCA-salt hypertensive rats

AimsThere is significant evidence that the endocannabinoid system (ECS) takes part in the regulation of the cardiovascular system in hypertension. It is quite well established that hypertension causes several changes in the heart metabolism, but it is still unknown whether the ECS affects this process. Therefore, we investigated the influence of prolonged ECS activation on myocardial lipid metabolism in deoxycorticosterone acetate (DOCA)-salt hypertensive rats by chronic fatty acid amide hydrolase (FAAH) inhibition. Materials and methodsWe examined the uptake and oxidation of palmitic acid during the heart perfusion as well as intramyocardial and plasma lipid contents using gas liquid chromatography. Total, plasmalemmal and intracellular expressions of selected proteins were estimated by the Western blot technique. Moreover, the left ventricle's morphology, including myocardial vessels density, was measured using immunohistochemistry. Key findingsWe demonstrated that hypertension induced cardiomyocytes and myocardial blood vessels hypertrophy, followed by a reduction in myocardial palmitate oxidation. Interestingly, prolonged activation of the ECS in the normotensive rats induced cardiomyocyte enlargement and intensified fatty acids metabolism. We have also shown that FAAH inhibition improved morphology of coronary blood vessels and only partially maintained its effect on lipid metabolism in the DOCA-salt hearts (i.e. elevated plasma and intramyocardial TAG contents as well as plasmalemmal FAT/CD36 and total FATP1 expressions). SignificanceThis study revealed that chronic FAAH inhibition has no protective effects on the heart lipid metabolism in hypertension.

The Sodium-Glucose Cotransporter 2 Inhibitor Dapagliflozin Prevents Cardiomyopathy in a Diabetic Lipodystrophic Mouse Model.

Type 2 diabetes mellitus (T2DM) is a well-recognized independent risk factor for heart failure. T2DM is associated with altered cardiac energy metabolism, leading to ectopic lipid accumulation and glucose overload, the exact contribution of these two parameters remaining unclear. To provide new insight into the mechanism driving the development of diabetic cardiomyopathy, we studied a unique model of T2DM: lipodystrophic Bscl2-/- (seipin knockout [SKO]) mice. Echocardiography and cardiac magnetic resonance imaging revealed hypertrophic cardiomyopathy with left ventricular dysfunction in SKO mice, and these two abnormalities were strongly correlated with hyperglycemia. Surprisingly, neither intramyocardial lipid accumulation nor lipotoxic hallmarks were detected in SKO mice. [18F]Fludeoxyglucose positron emission tomography showed increased myocardial glucose uptake. Consistently, the O-GlcNAcylated protein levels were markedly increased in an SKO heart, suggesting a glucose overload. To test this hypothesis, we treated SKO mice with the hypoglycemic sodium-glucose cotransporter 2 (SGLT2) inhibitor dapagliflozin and the insulin sensitizer pioglitazone. Both treatments reduced the O-GlcNAcylated protein levels in SKO mice, and dapagliflozin successfully prevented the development of hypertrophic cardiomyopathy. Our data demonstrate that glucotoxicity by itself can trigger cardiac dysfunction and that a glucose-lowering agent can correct it. This result will contribute to better understanding of the potential cardiovascular benefits of SGLT2 inhibitors.

Lipolytic Rate Associated With Intramyocardial Lipid in an HIV Cohort Without Increased Lipolysis.

Individuals with HIV have an elevated risk for developing cardiovascular disease compared to controls, particularly in relationship to abnormal deposition of lipid within various body compartments. Dysregulation of lipolysis may contribute to abnormal deposition of lipid in non-adipose tissues such as the heart, leading to untoward health consequences. To evaluate potential relationships between rates of whole-body lipolysis and intramyocardial lipid content in HIV-infected subjects compared to healthy controls. Cross-sectional study. National Institutes of Health Clinical Research Center in Bethesda, Maryland. Forty-six HIV-infected adults and 12 controls without known cardiovascular disease. Intramyocardial lipid content quantified by MRI and rates of lipolysis determined using stable isotope tracer techniques. We observed a significant positive correlation between the rate of appearance of glycerol and intramyocardial lipid overall (r = 0.323; P = .014) and among the HIV group separately (r = 0.361; P = .014). Multivariate regression analyses including HIV, lipid-lowering therapy, and diabetes identified both rate of appearance of glycerol and age as independent significant predictors of intramyocardial lipid (P = .01 and P = .03, respectively), but these were not significant with inclusion of visceral adipose in the analyses. To our knowledge, this study is among the first in humans to characterize the relationship between lipid deposition in the myocardium and direct measurement of whole-body fatty acid metabolism. Our current findings contribute to the growing understanding of factors that promote myocardial steatosis, such as visceral adiposity, and implicate lipolysis as a potential target for interventions to optimize myocardial health.

Abstract 390: End-stage Human Heart Failure is Characterized by a Deficit in Energetic Lipids in Both Diabetic and Non-diabetic Patients

Introduction: Animal models and human studies have identified increased intramyocardial lipid accumulation and a lipotoxicity hypothesis has been emerging as a mechanism of myocardial dysfunction in diabetes. We have identified a significant decrease in energetic lipids in chronic advanced non-diabetic heart failure. We hypothesized that intramyocardial lipid species would be increased in diabetic as compared to non-diabetic end-stage heart failure patients. Methods: Left ventricular samples procured at the time of orthotopic heart transplantation from non-diabetic (IDCM n=8) and diabetic (DCMDM n=8) patients as well as organ donors with (NFDM) and without a history of diabetes (Donor) were quantitated for lipids with high-resolution mass spectrometry . Stable isotope labeled essential nutrient in cell culture internal standards for acyl-CoAs were generated using [ 13 C 3 15 N 1 ]-pantotheonate in Hepa1c1c7 cells. Results: The lipidomic signature of end-stage failing myocardium marked by a significant decrease in energetic lipids, a decreased myocardial Succinyl CoA (p-value 0.0079 for failing versus non-failing diabetic subjects) and a decreased ratio of [Succinyl CoA]/[Acetyl Coa] consistent with deficient TCA cycling, is indistinguishable in diabetic and non-diabetic patients (Figure 1). Discussion: Despite the known bioenergetic deficits in insulin-resistant diabetes, we have not identified any significant differences between diabetic and non-diabetic subjects in the lipidomic signature of end-stae failing myocardium. Future studies are needed with focused metabolomics to elucidate differences in the diabetic phenotype of human heart failure.

Abnormal Myocardial Function Is Related to Myocardial Steatosis and Diffuse Myocardial Fibrosis in HIV-Infected Adults.

Impaired cardiac function persists in the era of effective human immunodeficiency virus (HIV) therapy, although the etiology is unclear. We used magnetic resonance imaging (MRI) to measure intramyocardial lipid levels and fibrosis as possible contributors to HIV-associated myocardial dysfunction. A cross-sectional study of 95 HIV-infected and 30 matched-healthy adults, without known cardiovascular disease (CVD) was completed. Intramyocardial lipid levels, myocardial fibrosis, and cardiac function (measured on the basis of strain) were quantified by MRI. Systolic function was significantly decreased in HIV-infected subjects as compared to controls (mean radial strain [±SD], 21.7 ± 8.6% vs 30.5 ± 14.2%; P = .004). Intramyocardial lipid level and fibrosis index were both increased in HIV-infected subjects as compared to controls (P ≤ .04 for both) and correlated with the degree of myocardial dysfunction measured by strain parameters. Intramyocardial lipid levels correlated positively with antiretroviral therapy duration and visceral adiposity. Further, impaired myocardial function was strongly correlated with increased monocyte chemoattractant protein 1 levels (r = 0.396, P = .0002) and lipopolysaccharide binding protein levels (r = 0.25, P = .02). HIV-infected adults have reduced myocardial function as compared to controls in the absence of known CVD. Decreased cardiac function was associated with abnormal myocardial tissue composition characterized by increased lipid levels and diffuse myocardial fibrosis. Metabolic alterations related to antiretroviral therapy and chronic inflammation may be important targets for optimizing long-term cardiovascular health in HIV-infected individuals.