Ketone Body Utilization Research Articles

Fueling the Heart: What Are the Optimal Dietary Strategies in Heart Failure?

Heart failure (HF) is a global health concern with rising incidence and poor prognosis. While the essential role of nutritional and dietary strategies in HF patients is acknowledged in the existing scientific guidelines and clinical practice, there are no comprehensive nutritional recommendations for optimal dietary management of HF. In this review, we discuss results from recent studies on the obesity paradox and the effects of calorie restriction and weight loss, intermittent fasting, the Western diet, the Mediterranean diet, the ketogenic diet, and the DASH diet on HF progression. Many of these strategies remain under clinical and basic investigation for their safety and efficacy, and there is considerable heterogeneity in the observed response, presumably because of heterogeneity in the pathogenesis of different types of HF. In addition, while specific aspects of cardiac metabolism, such as changes in ketone body utilization, might underlie the effects of certain dietary strategies on the heart, there is a critical divide between supplement strategies (i.e., with ketones) and dietary strategies that impact ketogenesis. This review aims to highlight this gap by exploring emerging evidence supporting the importance of personalized dietary strategies in preventing progression and improving outcomes in the context of HF.

Abstract 442: Exploring targetable pathways: Unveiling changes in tumor physiology through dietary modification by a ketogenic diet

Abstract Background: A ketogenic diet, with high fat (90% kCal) and low carbohydrate (5% kCal) intake, induces ketosis [2], altering cancer cell carbon utilization toward the tricarboxylic acid cycle (TCA) [3]. While the overall impact on cancer growth is unclear, most literature suggests an anti-cancer effect. Our hypothesis aims to uncover pancreatic cancer cell adaptations to the ketogenic diet, revealing metabolic vulnerabilities for informed therapeutic strategies. Methods: Mice on a ketogenic or normal diet (control) underwent pancreatic cancer xenograft observation. Tumor metabolites were analyzed with LC/GC-MS, oxidative stress with NAD(P)+/NAD(P)H, and Lipid Peroxidation assays. Western blot assessed enzyme expression. In vitro studies used Seahorse FX Analyzer for mitochondrial function and PicoGreen for cell growth quantification. Ivosidenib and CB839 were used for combination therapies. Result: A ketogenic diet induces a metabolic shift in pancreatic cancer, altering nutrient and metabolite levels in diverse in vivo models. Besides the expected increase in TCA metabolites, heightened amino acid anaplerosis, particularly with glutamine and glutamate, was observed. Examination of the diet's impact on oxidative phosphorylation enzymes revealed increased BDH1 expression, aiding ketone body utilization, and upregulation of cytosolic IDH1 for antioxidant defense. Enzymes involved in glutamine uptake and conversion, like ASCT2 and GLS, showed altered expression. Simultaneously, we explored tumor microenvironment vulnerabilities, detecting a significant increase in reactive oxygen species (ROS) levels, specifically lipid peroxidation, in mice on the ketogenic diet. Given these pancreatic cancer adaptations, we hypothesized that combining therapeutics to elevate ROS levels and target the glutamine pathway would substantially impede tumor growth. To test this, we combined a ketogenic diet with an IDH1 inhibitor for antioxidant defense hindrance and a glutaminase inhibitor to impair mitochondrial function, resulting in a marked reduction in tumor proliferation compared to individual treatments. Conclusion: A ketogenic diet demonstrates a robust anti-tumor effect in various pancreatic cancer mouse models, likely arising from the diminished glucose and increased fatty acid load inherent in the diet. Metabolic adaptation towards an oxidative phosphorylation (OXPHOS) phenotype makes pancreatic cancer especially susceptible to antioxidant and mitochondrial inhibitors, as well as inhibitors of glutamine-metabolizing enzymes. Citation Format: Omid Hajihassani, Mehrdad Zarei, Soubhi Tahhan, Peter Gallagher, William Beegan, James Choi, Shihong Lei, Aya Murray, Alexander Loftus, Kevin Lebo, Helen Cheng, Anusha Mudigonda, Sydney Alibeckoff, Karen Ji, Jonathan Hue, Hallie Graor, Jordan Winter. Exploring targetable pathways: Unveiling changes in tumor physiology through dietary modification by a ketogenic diet [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 442.

Fasting Plasma Ketone Bodies Are Associated with NT-proBNP: A Potential Mechanism to Provide Fuel for the Failing Heart.

Background: Heart failure (HF) features a shift in metabolism towards enhanced utilization of ketone bodies. While elevations in plasma natriuretic peptides represent a biochemical hallmark of HF, natriuretic peptides may promote lipolysis, thereby contributing to fatty acid availability for ketogenesis. Methods: We cross-sectionally tested to what extent fasting plasma total ketone bodies (measured using nuclear magnetic resonance spectroscopy) are associated with N-terminal pro-BNP (NT-proBNP; electrochemiluminescent sandwich immunoassay) in individuals with and without HF. Results: Among 6217 participants from the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) study, 203 were identified with HF. NT-proBNP was four-fold and total ketone bodies were 25% higher in HF participants (each p < 0.001). In both participants with and without HF, total ketone body levels correlated with NT-proBNP (r = 0.116 and 0.185, respectively; p < 0.001). In multivariable linear regression analysis adjusted for relevant covariates, total ketone bodies remained associated with NT-proBNP in the whole cohort (std β = 0.08, p < 0.001), without a difference in participants with and without HF (p interaction: 0.52). Conclusion: This general population-based study reveals an independent association of fasting total body ketone bodies with plasma NT-proBNP. Our findings suggest that a metabolic defense mechanism could be operative, providing the myocardium with ketone bodies to meet its energy demands.

Abstract B050: Determining the anti-cancer properties of a ketogenic diet against pancreatic cancer

Abstract Abstract: Background: A ketogenic regimen is high in fat (90%kCal) and low in carbohydrates (5% kCal), resulting in a state of ketosis[2]. Prior studies suggest that a ketogenic diet shifts carbon utilization in cancer cells from one that is predominantly glycolytic, towards the tricarboxylic acid cycle (TCA) in the mitochondria[3]. The net effect on cancer growth remains uncertain, but the majority of studies in the literature favor an anti-cancer signal. We hypothesize that molecular and biochemical insights into how pancreatic cancer cells adapt to a ketogenic diet will uncover metabolic vulnerabilities and nominate rationally designed therapeutic strategies to effectively partner with the diet. Methods: A ketogenic diet was administered to mice, along with a normal diet in control mice. Pancreatic cancer xenografts were monitored for growth and harvested for biochemical analyses. Tumors were analyzed for metabolites by LC/GC-MS and for oxidative stress by measuring the levels of NADP+/NADPH, NAD+/NADH and Lipid Peroxidation assay. Enzyme expression was assessed by Western blot. For in vitro studies, mitochondrial function was analyzed by the Seahorse FX Analyzer and cell growth was measured by PicoGreen DNA quantitation. Result: A ketogenic diet slowed pancreatic cancer growth in multiple in vivo models, including MIA-PaCa2, KPC and patient derived xenografts. TCA metabolites were broadly increased in xenografts exposed to a ketogenic diet. In these mouse tumors, metabolic enzymes associated with the TCA cycle were markedly upregulated, pointing to an effect on gene expression. Specifically, the expression of BDH1 (a ketolytic enzyme allowing ketone body utilization in cancer cells), IDH1 (cytosolic and supports antioxidant defense and mitochondria through NADPH and α-ketoglutarate) and IDH2 (a homolog of IDH1 in the mitochondria) were all increased. In contrast, the glycolytic enzyme, G3P, was reduced. 3). additionally, a ketogenic diet induced oxidative stress in pancreatic cancer in vivo. Based on the adaptations observed in pancreatic cancer, we combined a ketogenic diet with an inhibitor of IDH1 to thwart antioxidant defense and impair mitochondrial function. The combination resulted in markedly reduced tumor proliferation, compared to either treatment alone. In vitro studies revealed that low glucose and fatty acids are likely the major drivers of reduced pancreatic cancer cell proliferation with a ketogenic diet, while exogenous ketone bodies are utilized for energy by mitochondria under glucose withdrawal and generally have a pro-tumor effect. Conclusion: A ketogenic diet has a strong anti-tumor effect in multiple pancreatic cancer mouse models, and the effect is likely a result of the low glucose and increased fatty acid load associated with the diet. Metabolic adaptation towards an OXPHOS phenotype renders pancreatic cancer especially susceptible to antioxidant and mitochondrial inhibitors. Citation Format: Mehrdad Zarei, Soubhi Tahhan, Peter Gallagher, William Beegan, Alexander Loftus, Kevin Lebo, Shihong Lei, Helen Cheng, Anusha Mudigonda, Jonathan Hue, Hallie Graor, Omid Hajihassani, Jordan Winter, Karen Ji, Sydney Alibeckoff. Determining the anti-cancer properties of a ketogenic diet against pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B050.

Empagliflozin alters lipid metabolism in the myocardium and liver in a prediabetes model with severe dyslipidemia.

Recent studies suggest that empagliflozin reduces total and cardiovascular mortality in both diabetic and nondiabetic subjects. Although the exact mechanism is unclear, it is understood to positively affect myocardial energetics, including the metabolism of ketone bodies, lipids, and fatty acids. In this study, we compared empagliflozin effects on lipid metabolism in the heart and liver in a prediabetic rat model with severe dyslipidemia. Wistar rats served as the control group, while hereditary hypertriglyceridemic (HHTg) rats were used as a nonobese, prediabetic model. Rats were treated with or without empagliflozin at a dose of 10mg/kg body weight (BW) for 8weeks. In HHTg rats, empagliflozin decreased body weight and adiposity, improved glucose tolerance, and decreased serum triacylglycerols (TAGs) (p < 0.001). Empagliflozin decreased the activity and gene expression of the lipogenic enzyme SCD-1 (p < 0.001) in the myocardium, which may have led to a decrease in the ectopic accumulation of TAGs and lipotoxic diacylglycerols and lysophosphatidylcholines (p < 0.001). Changes in the myocardial phosphatidylcholine/phosphatidylethanolamine ratio (p < 0.01) and in the fatty acid profile of myocardial phospholipids may have contributed to the antifibrotic effects of empagliflozin. The anti-inflammatory effects of empagliflozin were evidenced by an increased IL-10/TNFα ratio (p < 0.001), a marked decrease in arachidonic acid metabolites (20-HETE, p < 0.001), and an increase in PUFA metabolites (14,15-EETs, p < 0.001) in the myocardium. However, empagliflozin did not significantly affect either the concentration or utilization of ketone bodies. In the liver, empagliflozin decreased lipogenesis and the accumulation of TAGs and lipotoxic intermediates. Its effect on arachidonic acid metabolites and alterations in n-3 PUFA metabolism was less pronounced than in the myocardium. Our findings suggest that empagliflozin treatment in the heart and liver reduced the accumulation of neutral lipids and lipotoxic intermediates and altered the metabolism of n-3 PUFA. In the heart, empagliflozin altered arachidonic acid metabolism, which is likely associated with the anti-inflammatory and antifibrotic effects of the drug. We assume that these alterations in lipid metabolism contribute to the cardioprotective effects of empagliflozin in prediabetic states with severe dyslipidemia.

Empagliflozin improves mitochondrial dysfunction in diabetic cardiomyopathy by modulating ketone body metabolism and oxidative stress

Ketone bodies are considered as an alternative energy source for diabetic cardiomyopathy (DCM) and can improve the energy supply of the heart muscle, suggesting that it may be an important area of research and development as a therapeutic target for DCM. Cumulative cardiovascular trials have shown that sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce cardiovascular events in diabetic populations. Whether SGLT2 inhibitors improve DCM by enhancing ketone body metabolism remains and whether they help prevent oxidative damage remains to be clarified. Here, we present the combined results of nine GSE datasets for diabetic cardiomyopathy (GSE215979, GSE161931, GSE145294, GSE161052, GSE173384, GSE123975, GSE161827, GSE210612, and GSE5606). We found significant up-regulated gene 3-hydroxymethylglutaryl CoA synthetase 2 (HMGCS2) and down-regulated gene 3-hydroxybutyrate dehydrogenase (BDH1) and 3-oxoacid CoA-transferase1 (OXCT1), respectively. Based on the analysis of the constructed protein interaction network, it was found that HMGCS2 was in the core position of the interaction network. In addition, Gene ontology (GO) enrichment analysis mainly focused on redox process, acyl-CoA metabolic process, catalytic activity, redox enzyme activity and mitochondria. The activity of HMGCS2 in DCM heart was increased, while the expression of ketolysis enzymes BDH1 and OXCT1 was inhibited. In vivo, Empagliflozin (Emp) treated DCM group significantly decreased ventricular weight, myocardial cell cross-sectional area, and myocardial fibrosis. In addition, Emp further promoted the activity of BDH1 and OXCT1, increased the utilization of ketone bodies, further promoted the activity of HMGCS2 in DCM, and increased the synthesis of ketone bodies, prevented mitochondrial breakage and dysfunction, increased myocardial ATP to provide sufficient energy, inhibited oxidative stress and apoptosis of cardiac cells ex vivo, and improved the myocardial dysfunction of DCM. Emp can improve mitochondrial dysfunction in diabetic cardiomyopathy by regulating ketone body metabolism and oxidative stress. These findings provide a theoretical basis for evaluating Emp as a treatment for DCM.

Melatonin attenuates an impairment of metabolic reprogramming in doxorubicin-induced cardiotoxicity: insights from metabolomics study in rats

Abstract Background Doxorubicin is an effective chemotherapeutic agent. Unfortunately, the clinical utilization of doxorubicin is limited due to cardiotoxicity. It was previously shown that doxorubicin caused the changes in glycolysis metabolome levels, fatty acid levels, and genes involving lipid metabolism in the heart. However, the pattern of metabolic reprogramming in doxorubicin-induced heart failure remains unknown. Moreover, the benefit of melatonin in attenuating doxorubicin-induced heart failure was previously revealed. Nonetheless, the potential benefits of melatonin on metabolic reprogramming in doxorubicin-induced heart failure has never been determined. Purposes Using liquid chromatography coupled with mass spectrometry-based targeted metabolomics, we identified the pattern of metabolic reprogramming in rats with doxorubicin-induced heart failure. In addition, the effects of melatonin on metabolic reprogramming in doxorubicin-induced heart failure were investigated. Methods Male Wistar rats (n=18) were divided into 3 groups (n=6/group) to receive either 1) normal saline solution as a vehicle, 2) 3 mg/kg/day of doxorubicin at days 0, 4, 8, 15, 22, and 29, and 3) 3 mg/kg/day of doxorubicin at days 0, 4, 8, 15, 22, and 29 plus 10 mg/kg/day of melatonin at days 0-29. At day 30, echocardiography and heart rate variability were done for an evaluation of cardiac function. The rats were then euthanized to collect ventricular cardiac tissues for metabolomics study. Results Comparing to vehicle-treated rats, the heart of rats treated with doxorubicin alone exhibited cardiac dysfunction, increased glucose and ketone body utilization, decreased fat utilization, decreased succinate oxidation, and decreased adenosine triphosphate (ATP) production. The co-treatment with melatonin effectively restored cardiac function, glucose and ketone body utilization, and ATP production in the heart. Interestingly, the co-treatment with melatonin also increased cardiac fatty acid oxidation, branched-chain amino acid catabolism, and anaplerosis (Figure). Conclusions Our findings highlighted the potential benefits of melatonin on cardiac metabolic reprogramming impaired by doxorubicin. These findings also suggested that melatonin could be considered as an adjunctive treatment for doxorubicin-induced heart failure in clinical settings.

Empagliflozin improves diastolic function in obese ZSF1 rats by restoring the cardiac mitochondrial respiratory capacity

Abstract Background Clinical studies demonstrated beneficial effects of Sodium-Glucose-Transporter 2 inhibitors (SGLT2i) on the combined risk of cardiovascular death or heart failure hospitalization in patients with heart failure with preserved ejection fraction (HFpEF). However, underlying processes leading to cardioprotection remain unclear. Purpose The present study aimed to elucidate the impact of Empagliflozin on myocardial function and metabolism in a rat model (ZSF1 rat) with established HFpEF and to analyze underlying mechanisms. Methods 24 week old, obese ZSF1 rats were randomized either receiving standard care (obese) or Empagliflozin (Empa, 30 mg/kg/d p.o.). ZSF1 lean rats (lean) served as healthy controls. All animals underwent a baseline, intermediate and final echocardiography. After 8 weeks of treatment, hemodynamics were measured invasively, blood samples were taken, cardiac mitochondrial function was assessed and left ventricular tissue was collected for molecular and histological analyses or for transmission electron microscopy (TEM). Results Compared to the obese control Empa treated obese rats demonstrated a significantly improved diastolic function already at 4 weeks of treatment (E/é: lean: 17.9 ± 0.8; obese: 23.7 ± 0.7, p&amp;lt;0.001 vs. lean; Empa: 21.0 ± 1.1, p&amp;lt;0.05 vs. lean; p&amp;lt;0.05 vs. obese), which reached the level of healthy controls after 8 weeks of treatment (E/é: lean: 17.5 ± 0.7; obese: 24.4 ± 1.1, p&amp;lt;0.001 vs. lean; Empa: 19.4 ± 0.8, p&amp;lt;0.001 vs. obese). This was accompanied by reduced hypertrophy, fibrosis, left ventricular stiffness and inflammation as well as by improved hemodynamics. Except for a slightly improved myocardial ketone body utilization in Empa treated rats, there was no shift in metabolic substrate preference between groups. Cardiac mitochondrial respiratory function observed in untreated obese rats was significantly impaired compared to healthy controls but restored by Empa treatment (Vmax of complex II: lean: 0.15 ± 0.007 nmol O2/s/mg, obese: 0.12 ± 0.004 nmol O2/s/mg, p&amp;lt;0.01 vs. lean; Empa: 0.17 ± 0.006 nmol O2/s/mg, p&amp;lt;0.05 vs. lean, p&amp;lt;0.001 vs. obese). Moreover, mitochondrial respiratory capacity correlated with diastolic function, suggesting a pivotal role of restored respiratory function for improved diastolic relaxation. TEM revealed reduced size of cardiac mitochondria in obese rats, which was significantly restored by Empa. Proteomic analysis demonstrated major changes in proteins involved in mitochondrial oxidative phosphorylation and antioxidant metabolism. Conclusions The present study demonstrates for the first time beneficial effects of Empaglifozin on cardiac remodeling, diastolic function and hemodynamics in an obese rat model of HFpEF. These effects were accompanied by improved mitochondrial respiratory function, enhanced ketone body utilization and improved antioxidant capacity.

Abstract 17042: Altered Myocardial Energy Substrate Utilization in Metabolic Syndrome May Impact Pathways Involved in Contractile Dysfunction in Ischemic Myocardium

Introduction: Metabolic syndrome (MetS) is increasingly prevalent and an independent risk factor for ischemic heart disease (IHD). MetS favors lipids over glucose as the predominant myocardial energy substrate. Similarly, in IHD, energy utilization is dependent on ketone bodies. Evidence is emerging that such changes in cardiac energy metabolism may drive contractile dysfunction, but the underlying processes have not been clarified in the context of coincident MetS and ischemia. Aims: The purpose of this multiomics study was to define the global metabolic state of ischemic myocardium in the setting of MetS, with a focus on energy metabolism and pathways modulating myocardial function and contractility. We hypothesized MetS would further shift substrate utilization away from glycolysis to favor ketone bodies, contributing to pathways of contractile dysfunction in injured myocardium. Methods: We used our well-established porcine model of diet-induced MetS and chronic myocardial ischemia to study effects on left ventricular tissue. Tissue samples from MetS swine and controls were analyzed using targeted LC-MS/MS for polar metabolites, RNA-seq, proteomics, and computational nonnegative matrix factorization. Results: MetS swine had altered bioavailability of 302 polar metabolites together with changes in gene expression of enzymes involved in glycolysis, fatty acid metabolism, ketone body utilization, and abnormal activation of renin-angiotensin-aldosterone system (RAAS). MetS swine also had reduced expression of Apelin protein, a potent stimulator of cardiac contractility (Figure). Conclusions: Our data show MetS enzymatically downregulates glycolysis and upregulates ketone body utilization together with derangement in RAAS in injured myocardium. Decreased Apelin expression may contribute to lipid-induced cardiac dysfunction through maladaptive effects on contractility and remodeling, and thus may serve as a future therapeutic target.

Advances in Metabolic Remodeling and Intervention Strategies in Heart Failure.

The heart is the most energy-demanding organ throughout the whole body. Perturbations or failure in energy metabolism contributes to heart failure (HF), which represents the advanced stage of various heart diseases. The poor prognosis and huge economic burden associated with HF underscore the high unmet need to explore novel therapies targeting metabolic modulators beyond conventional approaches focused on neurohormonal and hemodynamic regulators. Emerging evidence suggests that alterations in metabolic substrate reliance, metabolic pathways, metabolic by-products, and energy production collectively regulate the occurrence and progression of HF. In this review, we provide an overview of cardiac metabolic remodeling, encompassing the utilization of free fatty acids, glucose metabolism, ketone bodies, and branched-chain amino acids both in the physiological condition and heart failure. Most importantly, the latest advances in pharmacological interventions are discussed as a promising therapeutic approach to restore cardiac function, drawing insights from recent basic research, preclinical and clinical studies.

Antiepileptics pharmacotherapy or antidiabetics may hold potential in ‎treatment of ‎‎epileptic ‎patients with diabetes mellitus: A narrative review

Several studies have reported the association of diabetes mellitus with epilepsy. With respect to ‎the management of diabetes–epilepsy patients, these studies pointed out the beneficial effects of ‎the ketogenic diet. Ketogenic diets may have antiepileptic properties as the utilization of ketone ‎bodies in the brain instead of glucose delays or inhibits the degradation of γ-aminobutyric acid ‎‎(GABA) transaminase, and thereby enhances the concentration of GABA. By restoring normal ‎intracerebral GABA levels and reducing the cerebral inflammation linked to epilepsy, metformin ‎is useful in preventing seizures. Sitagliptin is one of the dipeptidyl dipeptidase-4 inhibitors, ‎which have a positive impact on epilepsy in experimental animal models with pentylenetetrazole-‎induced seizures, by reducing reactive oxygen species, (antioxidant effect), normalization of ‎GABA level, suppression of neuroinflammation (autophagy) and reduced neuronal damage ‎‎(antiapoptotic effect). Weight gain is a well-known side effect of anti-seizure medications. ‎Sodium valproate can cause dyslipidemia and inhibit glucose transporter-1 in the brain, putting ‎patients with epilepsy and diabetes at risk of developing atherosclerosis. It's worth looking at ‎how ferroptosis and autophagy contribute to the etiology of diabetes and epilepsy, as well as ‎how antiepileptics and antidiabetics alter these pathological processes. Therefore, it was worth ‎performing a narrative-review on the effects of antiepileptics on diabetes, the effect of ‎antidiabetics on epilepsy, as well the net results of antiepileptic–antidiabetic interactions in those ‎patients.‎

Ketone bodies supplementation restores the barrier function, induces a metabolic switch, and elicits beta-hydroxybutyrate diffusion across a monolayer of iPSC-derived brain microvascular endothelial cells

Glucose constitutes the main source of energy for the central nervous system (CNS), its entry occurring at the blood-brain barrier (BBB) via the presence of glucose transporter 1 (GLUT1). However, under food intake restrictions, the CNS can utilize ketone bodies (KB) as an alternative source of energy. Notably, the relationship between the BBB and KBs and its effect on their glucose metabolism remains poorly understood. In this study, we investigated the effect of glucose deprivation on the brain endothelium in vitro, and supplementation with KBs using induced pluripotent stem cell (iPSC)-derived brain microvascular endothelial cell-like cells (iBMECs).Glucose-free environment significantly decreased cell metabolic activity and negatively impacted the barrier function. In addition, glucose deprivation did not increase GLUT1 expression but also resulted in a decrease in glucose uptake and glycolysis. Supplementation of glucose-deprived iBMECs monolayers with KB showed no improvement and even worsened upon treatment with acetoacetate. However, under a hypoglycemic condition in the presence of KBs, we noted a slight improvement of the barrier function, with no changes in glucose uptake. Notably, hypoglycemia and/or KB pre-treatment elicited a saturable beta-hydroxybutyrate diffusion across iBMECs monolayers, such diffusion occurred partially via an MCT1-dependent mechanism. Taken together, our study highlights the importance of glucose metabolism and the reliance of the brain endothelium on glucose and glycolysis for its function, such dependence is unlikely to be covered by KBs supplementation. In addition, KB diffusion at the BBB appeared induced by KB pre-treatment and appears to involve an MCT1-dependent mechanism.

Recurrent metabolic acidosis: is it by chance?

Succinyl CoA 3 oxoacid CoA transferase deficiency (SCOTD) is an autosomal recessive disorder of ketone body utilization which present with recurrent episodes of metabolic acidosis. We have a 23-month old child who presented with 3 episodes of metabolic acidosis. Each time the toxicology profile came positive for ethyl alcohol. We couldn’t get any history suggestive of poisoning. So we were in a great dilemma and considered the possibility of Munchausen syndrome by proxy and a metabolic cause. Even though the initial genetic result was nonspecific when we reanalyzed the sample for genetic analysis it came positive as Succinyl CoA 3 oxoacid CoA transferase (SCOT) deficiency. The child required intensive care support in all 3 times. We were able to manage the child with supportive measures each time. Now the child is under regular follow up and doing well. SCOTD should be considered in any children presenting as recurrent episodes of metabolic acidosis. The rarity of this disorder will lead to the diagnostic dilemma that we face as like in this case.

Effects of melatonin on cardiac metabolic reprogramming in doxorubicin-induced heart failure rats: A metabolomics study for potential therapeutic targets.

Using mass spectrometry-based targeted metabolomics, we aimed to determine the pattern of cardiac metabolic reprogramming and energetics in doxorubicin-induced heart failure. More importantly, we aimed to identify the potential effects of melatonin on cardiac metabolic reprogramming and energetics in doxorubicin-induced heart failure. Male Wistar rats (n = 18) were randomly divided into three groups (n = 6/group) to receive either (1) normal saline solution as a control, (2) 3 mg/kg/day of doxorubicin on Days 0, 4, 8, 15, 22, and 29, or (3) 3 mg/kg/day of doxorubicin on Days 0, 4, 8, 15, 22, and 29 plus 10 mg/kg/day of melatonin on Days 0-29. On Day 30, echocardiography was carried out and heart rate variability was analyzed for the evaluation of cardiac function. The rats were euthanized on the following day to enable the collection of ventricular cardiac tissue. Compared to the control group, the hearts of rats treated with doxorubicin alone exhibited impaired cardiac function, increased glucose and ketone body utilization, decreased fat utilization, decreased succinate oxidation, and decreased production of adenosine triphosphate. The cotreatment with melatonin could restore cardiac function, glucose and ketone body utilization, and adenosine triphosphate production in the heart. Interestingly, the cotreatment with melatonin led to an increase in cardiac fatty acid oxidation, branched-chain amino acid catabolism, and anaplerosis. All of these findings highlighted the potential efficacy of melatonin with regard to cardiac metabolic reprogramming and energetics. Our findings also suggested that melatonin could be considered as an adjunctive treatment for doxorubicin-induced heart failure in clinical practice.

High-Fat-Diet Suppressed Ketone Body Utilization for Lipogenic Pathway in Brown Adipose Tissues.

Brown adipose tissue (BAT) consumes excess lipids and produces lipid metabolites as ketone bodies. These ketone bodies are then recycled for lipogenesis by the enzyme acetoacetyl-CoA synthetase (AACS). Previously, we found that a high-fat diet (HFD) upregulated AACS expression in white adipose tissue. In this study, we investigated the effects of diet-induced obesity on AACS in BAT. When 4-week-old ddY mice were fed a HFD or high-sucrose diet (HSD) for 12 weeks, a significant decrease in Aacs, acetyl-CoA carboxylase-1 (Acc-1), and fatty acid synthase (Fas) expression was observed in the BAT of the HFD group, whereas expression was not affected in the HSD group. In vitro analysis showed decreased Aacs and Fas expression in rat primary-cultured brown adipocytes following isoproterenol treatment for 24 h. In addition, the suppression of Aacs by siRNA markedly decreased the expression of Fas and Acc-1 but did not affect the expression of uncoupling protein-1 (UCP-1) or other factors. These results suggested that HFD may suppress ketone body utilization for lipogenesis in BAT and that AACS gene expression may be important for regulating lipogenesis in BAT. Therefore, the AACS-mediated ketone body utilization pathway may regulate lipogenesis under conditions of excess dietary fat.

Abstract 291: A ketogenic diet rewires pancreatic cancer metabolism towards an actionable metabolic

Abstract Background: A ketogenic regimen is high in fat (90%kCal) and low in carbohydrates (5% kCal), resulting in a state of ketosis[2]. Prior studies suggest that a ketogenic diet shifts carbon utilization in cancer cells from one that is predominantly glycolytic, towards the tricarboxylic acid cycle (TCA) in the mitochondria[3]. The net effect on cancer growth remains uncertain, but the majority of studies in the literature favor an anti-cancer signal. We hypothesize that molecular and biochemical insights into how pancreatic cancer cells adapt to a ketogenic diet will uncover metabolic vulnerabilities and nominate rationally designed therapeutic strategies to effectively partner with the diet. Methods: A ketogenic diet was administered to mice, along with a normal diet in control mice. Pancreatic cancer xenografts were monitored for growth and harvested for biochemical analyses. Tumors were analyzed for metabolites by LC/GC-MS and for oxidative stress by measuring the levels of NAD+/NADH and Lipid Peroxidation assays. Enzyme expression was assessed by Western blot. For in vitro studies, mitochondrial function was analyzed by the Seahorse FX Analyzer and cell growth was measured by PicoGreen DNA quantitation. Result: A ketogenic diet slowed pancreatic cancer growth in multiple in vivo models, including MIA-PaCa2, KPC and patient derived xenografts. TCA metabolites were broadly increased in xenografts exposed to a ketogenic diet. In these mouse tumors, metabolic enzymes associated with the TCA cycle were markedly upregulated, pointing to an effect on gene expression. Specifically, the expression of BDH1 (a ketolytic enzyme allowing ketone body utilization in cancer cells), IDH1 (cytosolic and supports antioxidant defense and mitochondria through NADPH and α-ketoglutarate) and IDH2 (a homolog of IDH1 in the mitochondria) were all increased. In contrast, the glycolytic enzyme, G3P, was reduced. 3). additionally, a ketogenic diet induced oxidative stress in pancreatic cancer in vivo. Based on the adaptations observed in pancreatic cancer, we combined a ketogenic diet with an inhibitor of IDH1 to thwart antioxidant defense and impair mitochondrial function. The combination resulted in markedly reduced tumor proliferation, compared to either treatment alone. In vitro studies revealed that low glucose and fatty acids are likely the major drivers of reduced pancreatic cancer cell proliferation with a ketogenic diet, while exogenous ketone bodies are utilized for energy by mitochondria under glucose withdrawal and generally have a pro-tumor effect. Conclusion: A ketogenic diet has a strong anti-tumor effect in multiple pancreatic cancer mouse models, and the effect is likely a result of the low glucose and increased fatty acid load associated with the diet. Metabolic adaptation towards an OXPHOS phenotype renders pancreatic cancer especially susceptible to antioxidant and mitochondrial inhibitors. Citation Format: Omid Hajihassani, Mehrdad Zarei, Alaxander Loftus, Soubhi Tahan, Peter Gallagher, Kevin Lebo, Helen Chang, Elise Moore, Anusha Mudigonda, Jonathan Hue, Hallie Graor, Jordan Winter. A ketogenic diet rewires pancreatic cancer metabolism towards an actionable metabolic [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 291.

Swimming Endurance Capacity of Mice is Increased by Chronic Consumption of Medium-Chain Triglycerides

The effect of chronic administration of medium-chain triglycerides (MCT) on swimming endurance (swim capacity) was investigated in male Std ddY mice. The mice were fed a diet containing 80 g MCT + 20 g long-chain triglycerides (LCT)/kg diet for 6 wk; mice fed diet containing 100 g LCT/kg diet were used as controls. After being accustomed to swimming, the mice were subjected to forced swimming every 2 d in the current water pool that we had developed, and the total swimming period until exhaustion was measured. The total swimming period was used as the index of swim capacity. The group fed MCT showed significantly greater swim capacity than the control group (89.5 ± 2.5 vs. 80.2 ± 2.0 min). In another experiment, after 4 wk of MCT diet consumption, significantly greater swim capacity was found in untrained mice. The major metabolic consequences of the adaptations of muscle to prolonged MCT administration during endurance training were higher activities of 3-oxo acid CoA-transferase (P < 0.01), citrate synthase (P < 0.1) and malate dehydrogenase (P < 0.1). These findings suggest that increases in the enzyme activities of the tricarboxylic acid cycle and ketone body utilization associated with the chronic administration of an MCT-containing diet enhance swim capacity in mice.

Ketone Bodies and Cardiovascular Disease: An Alternate Fuel Source to the Rescue.

The increased metabolic activity of the heart as a pump involves a high demand of mitochondrial adenosine triphosphate (ATP) production for its mechanical and electrical activities accomplished mainly via oxidative phosphorylation, supplying up to 95% of the necessary ATP production, with the rest attained by substrate-level phosphorylation in glycolysis. In the normal human heart, fatty acids provide the principal fuel (40-70%) for ATP generation, followed mainly by glucose (20-30%), and to a lesser degree (<5%) by other substrates (lactate, ketones, pyruvate and amino acids). Although ketones contribute 4-15% under normal situations, the rate of glucose use is drastically diminished in the hypertrophied and failing heart which switches to ketone bodies as an alternate fuel which are oxidized in lieu of glucose, and if adequately abundant, they reduce myocardial fat delivery and usage. Increasing cardiac ketone body oxidation appears beneficial in the context of heart failure (HF) and other pathological cardiovascular (CV) conditions. Also, an enhanced expression of genes crucial for ketone break down facilitates fat or ketone usage which averts or slows down HF, potentially by avoiding the use of glucose-derived carbon needed for anabolic processes. These issues of ketone body utilization in HF and other CV diseases are herein reviewed and pictorially illustrated.

A Novel Mutation in the OXCT1 Gene Causing Succinyl-CoA:3-Ketoacid CoA Transferase (SCOT) Deficiency Starting with Neurologic Manifestations.

Succinyl-CoA:3-oxoacid CoA-transferase (SCOT) deficiency is an inborn error of ketone body utilization characterized by intermittent ketoacidosis crises. This study reports the first Iranian patient with SCOT deficiency who presented with seizure and hypotonia at birth. Accordingly, she was consequently re-hospitalized due to hypotonia and respiratory distress. Laboratory tests revealed hyperammonemia, ketonuria, and metabolic acidosis. Besides, the plasma glucose level was normal without any other abnormality. Despite treatment with high-dose bicarbonate, severe acidosis persisted. Poor response to treatment raised a significant diagnostic challenge among specialists until genetic investigation identified a homozygous nonsense mutation (c.79G>T; p.Gly27*) in the OXCT1 gene (NM_000436), causing SCOT deficiency. Genetic studies help clinicians achieve a definite diagnosis of such metabolic disorders. In this case, the accurate and early diagnosis of SCOT deficiency opened new therapeutic possibilities, including frequent carbohydrate-rich meals and low fat and protein diet. Moreover, our findings expand the mutational and clinical spectrum of SCOT deficiency.

Was there a need for high carbohydrate content in Neanderthal diets?

AbstractObjectivesIn a recent paper, Hardy et al. (2022, Journal of Human Evolution 162: 103105) claim that the physiological Neanderthal requirement for plant carbohydrates may have reached 50%–60% of caloric intake, inferred from modern dietary guidelines and a putative need for high carbohydrate intake in pregnant/breastfeeding women and athletes. The aim of this article is to critically re‐examine these arguments under the premise that hominins could adapt to hypercarnivorous diets and low carbohydrate consumption.Materials and MethodsLiterature on ketogenic and carnivore diets was retrieved. A case report of a male rugby player voluntarily undertaking a carnivore diet under medical supervision is presented.ResultsHuman metabolism is highly flexible towards adapting to long‐term low carbohydrate intakes by producing and utilizing ketone bodies. The evidence base of dietary guidelines is weak, and carbohydrate intake recommendations for athletes and during pregnancy/lactation are uncertain, making a translation to Neanderthal diets questionable. The studied rugby player maintained his sports performance and health over a 4‐months period despite minimal carbohydrate intake.DiscussionHuman physiology appears to have an extraordinary ability to utilize ketone bodies as a fuel for the brain and skeletal muscle, in particular also during exercise. The translation of dietary guidelines to Neanderthals and interpretation of studies in subjects not adapted to ketosis may be biased by a “glucocentric” perspective supposing that high carbohydrate intake is necessary for maintaining health. Allowing for the possibility of keto‐adaption leads to a more coherent integration of archeological and physiological data.