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Nature Communications Dec 2021Lactic acidosis, the extracellular accumulation of lactate and protons, is a consequence of increased glycolysis triggered by insufficient oxygen supply to tissues....
Lactic acidosis, the extracellular accumulation of lactate and protons, is a consequence of increased glycolysis triggered by insufficient oxygen supply to tissues. Macrophages are able to differentiate from monocytes under such acidotic conditions, and remain active in order to resolve the underlying injury. Here we show that, in lactic acidosis, human monocytes differentiating into macrophages are characterized by depolarized mitochondria, transient reduction of mitochondrial mass due to mitophagy, and a significant decrease in nutrient absorption. These metabolic changes, resembling pseudostarvation, result from the low extracellular pH rather than from the lactosis component, and render these cells dependent on autophagy for survival. Meanwhile, acetoacetate, a natural metabolite produced by the liver, is utilized by monocytes/macrophages as an alternative fuel to mitigate lactic acidosis-induced pseudostarvation, as evidenced by retained mitochondrial integrity and function, retained nutrient uptake, and survival without the need of autophagy. Our results thus show that acetoacetate may increase tissue tolerance to sustained lactic acidosis.
Topics: Acetoacetates; Acidosis, Lactic; Cellular Reprogramming; Energy Metabolism; Gene Expression; Humans; Hydrogen-Ion Concentration; Lactic Acid; Macrophages; Metabolic Engineering; Mitochondria; Mitophagy; Protective Agents; Tumor Microenvironment
PubMed: 34880237
DOI: 10.1038/s41467-021-27426-x -
Sports Medicine (Auckland, N.Z.) Dec 2022The ketone bodies acetoacetate (AcAc) and β-hydroxybutyrate (βHB) have pleiotropic effects in multiple organs including brain, heart, and skeletal muscle by serving as... (Review)
Review
The ketone bodies acetoacetate (AcAc) and β-hydroxybutyrate (βHB) have pleiotropic effects in multiple organs including brain, heart, and skeletal muscle by serving as an alternative substrate for energy provision, and by modulating inflammation, oxidative stress, catabolic processes, and gene expression. Of particular relevance to athletes are the metabolic actions of ketone bodies to alter substrate utilisation through attenuating glucose utilisation in peripheral tissues, anti-lipolytic effects on adipose tissue, and attenuation of proteolysis in skeletal muscle. There has been long-standing interest in the development of ingestible forms of ketone bodies that has recently resulted in the commercial availability of exogenous ketone supplements (EKS). These supplements in the form of ketone salts and ketone esters, in addition to ketogenic compounds such as 1,3-butanediol and medium chain triglycerides, facilitate an acute transient increase in circulating AcAc and βHB concentrations, which has been termed 'acute nutritional ketosis' or 'intermittent exogenous ketosis'. Some studies have suggested beneficial effects of EKS to endurance performance, recovery, and overreaching, although many studies have failed to observe benefits of acute nutritional ketosis on performance or recovery. The present review explores the rationale and historical development of EKS, the mechanistic basis for their proposed effects, both positive and negative, and evidence to date for their effects on exercise performance and recovery outcomes before concluding with a discussion of methodological considerations and future directions in this field.
Topics: Humans; Ketones; Ketone Bodies; Ketosis; Acetoacetates; 3-Hydroxybutyric Acid; Dietary Supplements
PubMed: 36214993
DOI: 10.1007/s40279-022-01756-2 -
American Journal of Alzheimer's Disease... 2022The ketone bodies, especially the β-hydroxybutyrate, had been shown to modulate the function of the central nervous system and prevent the pathological progression of...
The ketone bodies, especially the β-hydroxybutyrate, had been shown to modulate the function of the central nervous system and prevent the pathological progression of Alzheimer's disease (AD). However, little is known about the role of acetoacetate in the AD brain. Thus, we intraventricularly injected acetoacetate into familial AD mice (APPSWE) for 14 days and monitored their memory and biochemical changes. During the behavior test, acetoacetate at 100 mg/kg led to significant improvement in both Y-maze and novel object recognition tests (NORTs) (both P < .05), indicating ameliorating spatial and recognition memory, respectively. Biomedical tests revealed two mechanisms were involved. Firstly, acetoacetate inhibited the GPR43-pERK pathway, which led to apparent inhibition in tumor necrosis factor-α and Interleukin-6 expression in the hippocampus in a concentration-dependent manner. Secondarily, acetoacetate stimulated the expression of hippocampal brain-derived neurotrophic factor (BDNF). We concluded that acetoacetate could ameliorate AD symptoms and exhibited promising features as a therapeutic for AD.
Topics: 3-Hydroxybutyric Acid; Acetoacetates; Alzheimer Disease; Animals; Brain-Derived Neurotrophic Factor; Disease Models, Animal; Inflammation; Interleukin-6; Mice; Tumor Necrosis Factor-alpha
PubMed: 36113018
DOI: 10.1177/15333175221124949 -
Biotechnology and Bioengineering Nov 2021Whole-cell biosensors hold potential in a variety of industrial, medical, and environmental applications. These biosensors can be constructed through the repurposing of...
Whole-cell biosensors hold potential in a variety of industrial, medical, and environmental applications. These biosensors can be constructed through the repurposing of bacterial sensing mechanisms, including the common two-component system (TCS). Here we report on the construction of a range of novel biosensors that are sensitive to acetoacetate, a molecule that plays a number of roles in human health and biology. These biosensors are based on the AtoSC TCS. An ordinary differential equation model to describe the action of the AtoSC TCS was developed and sensitivity analysis of this model used to help inform biosensor design. The final collection of biosensors constructed displayed a range of switching behaviours at physiologically relevant acetoacetate concentrations and can operate in several Escherichia coli host strains. It is envisaged that these biosensor strains will offer an alternative to currently available commercial strip tests and, in future, may be adopted for more complex in vivo or industrial monitoring applications.
Topics: Acetoacetates; Biosensing Techniques; Escherichia coli; Escherichia coli Proteins; Gene Expression Regulation, Bacterial; Humans; Operon
PubMed: 34289076
DOI: 10.1002/bit.27897 -
Toxicology Letters May 2020Cultured kidney cells maintained in conventional growth media with high glucose levels exhibit increased glycolytic activity compared to the cells in vivo. In contrast,...
Cultured kidney cells maintained in conventional growth media with high glucose levels exhibit increased glycolytic activity compared to the cells in vivo. In contrast, renal proximal tubules utilize substrates such as ketone bodies and rely on mitochondrial oxidative phosphorylation. LLC-PK cells maintain many features of the proximal tubule but are exposed to glucose concentrations ranging from 17 to 25 mM. This may impact their reliability in predicting mitochondrial toxicity. This study is designed to test the impact of the ketone body acetoacetate on metabolic characteristics of LLC-PK cells. Basal respiration, maximal respiration, spare respiratory capacity and ATP-linked respiration were significantly increased in cells grown in growth medium supplemented with 5 mM acetoacetate. In contrast, glycolytic capacity, as well as glycolytic reserve were significantly reduced in the acetoacetate group. There was an increased expression in biomarkers of mitochondrial biogenesis, and an increase in mitochondrial protein expression. Cells grown in medium complemented with acetoacetate displayed a significantly lower LC when treated with clotrimazole and diclofenac. There was a marked increase in uncoupled respiration in the presence of diclofenac, while clotrimazole and ciprofibrate significantly decreased respiration in the acetoacetate. The results indicate that acetoacetate complemented media can alter cellular metabolism and increase sensitization to toxicants.
Topics: Acetoacetates; Animals; Cells, Cultured; Clotrimazole; Diclofenac; Fibric Acids; Glycolysis; Kidney; Mitochondria; Oxidation-Reduction; Swine
PubMed: 31962156
DOI: 10.1016/j.toxlet.2020.01.015 -
Journal of Leukocyte Biology Jun 2023Neutrophils express many surface receptors that sense environmental changes. One such sensor is FFAR2 (free fatty acid receptor 2), a receptor that detects gut...
Neutrophils express many surface receptors that sense environmental changes. One such sensor is FFAR2 (free fatty acid receptor 2), a receptor that detects gut microbiota-derived short-chain fatty acids. As such, FFAR2 has been regarded as a molecular link between metabolism and inflammation. Our recent studies on FFAR2, using its endogenous agonist propionate in combination with allosteric modulators, have identified several novel aspects of FFAR2 regulation. A recent study has also identified the ketone body acetoacetate as an endogenous ligand for mouse FFAR2. Whether human FFAR2 also recognizes acetoacetate and how this recognition modulates human neutrophil functions has not been investigated. In this study, we found that acetoacetate can induce a decrease of cAMP and translocation of β-arrestin in cells overexpressing FFAR2. In addition, we show that similar to propionate, FFAR2-specific allosteric modulators enhance acetoacetate-induced transient rise in cytosolic calcium, production of reactive oxygen species, and cell migration in human neutrophils. In summary, we demonstrate that human neutrophils recognize the ketone body acetoacetate through FFAR2. Thus, our data further highlight the key role of FFAR2 in inflammation and metabolism.
Topics: Humans; Mice; Animals; Receptors, G-Protein-Coupled; Propionates; Neutrophils; Acetoacetates; Ketone Bodies; Inflammation
PubMed: 36999365
DOI: 10.1093/jleuko/qiad035 -
Acta Biochimica Et Biophysica Sinica Jul 2021Acetoacetate (AA) is an important ketone body that is used as an oxidative fuel to supply energy for the cellular activities of various tissues, including the brain and...
Acetoacetate (AA) is an important ketone body that is used as an oxidative fuel to supply energy for the cellular activities of various tissues, including the brain and skeletal muscle. We recently revealed a new signaling role for AA by showing that it promotes muscle cell proliferation in vitro, enhances muscle regeneration in vivo, and ameliorates the dystrophic muscle phenotype of Mdx mice. In this study, we provide new molecular insight into this function of AA. We show that AA promotes C2C12 cell proliferation by transcriptionally upregulating the expression of muscle-specific miR-133b, which in turn stimulates muscle cell proliferation by targeting serum response factor. Furthermore, we show that the AA-induced upregulation of miR-133b is transcriptionally mediated by MEF2 via the Mek-Erk1/2 signaling pathway. Mechanistically, our findings provide further convincing evidence that AA acts as signaling metabolite to actively regulate various cellular activities in mammalian cells.
Topics: Acetoacetates; Animals; Cell Line; Cell Proliferation; Extracellular Signal-Regulated MAP Kinases; MAP Kinase Kinase Kinases; MAP Kinase Signaling System; MEF2 Transcription Factors; Mice; MicroRNAs; Myoblasts; Serum Response Factor
PubMed: 34184741
DOI: 10.1093/abbs/gmab079 -
Reproductive Biomedicine Online Jan 2023Does the ketone acetoacetate (AcAc) alone, or combined with β-hydroxybutyrate (βOHB), impact mouse embryo development, metabolism, histone acetylation and viability?
RESEARCH QUESTION
Does the ketone acetoacetate (AcAc) alone, or combined with β-hydroxybutyrate (βOHB), impact mouse embryo development, metabolism, histone acetylation and viability?
DESIGN
Pronucleate mouse oocytes were cultured in vitro in G1/G2 media supplemented with ketones (AcAc or AcAc + βOHB) at concentrations representing those in maternal serum during pregnancy (0.04 mmol/l AcAc, 0.1 mmol/l βOHB), standard diet consumption (0.1 mmol/l AcAc, 0.25 mmol/l βOHB), ketogenic diet consumption (0.8 mmol/l AcAc, 2 mmol/l βOHB) and diabetic ketoacidosis (2 mmol/l AcAc, 4 mmol/l βOHB). Day 5 blastocysts were assessed for cell allocation, glucose metabolism and histone acetylation. Day 4 blastocysts exposed to 0.8 mmol/l AcAc + 2 mmol/l βOHB were transferred to standard-fed recipient females, and E14.5 fetal and placental development assessed.
RESULTS
Exposure to 2 mmol/l AcAc or 0.8 mmol/l AcAc + 2 mmol/l βOHB did not impair blastocyst development, but significantly increased glucose consumption (P = 0.001 each), lowered glycolytic flux (P = 0.01, P < 0.001) and elevated trophectoderm (TE) histone 3 lysine 27 acetylation (H3K27ac; P < 0.001 each) compared with unexposed controls. Preimplantation AcAc + βOHB exposure reduced post-implantation fetal development by 25% (P = 0.037), and delayed female-specific fetal limb development (P = 0.019) and estimated fetal age (P = 0.019) compared with controls.
CONCLUSION
Preimplantation exposure to ketones affects underlying metabolism and histone acetylation in blastocysts that are associated with persistent, female-specific perturbations in fetal development. A periconceptional diet that elevates ketone concentrations may impair human embryonic viability.
Topics: Pregnancy; Mice; Humans; Female; Animals; 3-Hydroxybutyric Acid; Acetoacetates; Histones; Placenta; Ketones
PubMed: 36283935
DOI: 10.1016/j.rbmo.2022.09.018 -
Biochimica Et Biophysica Acta.... Jun 2020The ketone bodies, d-β-hydroxybutyrate and acetoacetate, are soluble 4-carbon compounds derived principally from fatty acids, that can be metabolised by many oxidative... (Review)
Review
The ketone bodies, d-β-hydroxybutyrate and acetoacetate, are soluble 4-carbon compounds derived principally from fatty acids, that can be metabolised by many oxidative tissues, including heart, in carbohydrate-depleted conditions as glucose-sparing energy substrates. They also have important signalling functions, acting through G-protein coupled receptors and histone deacetylases to regulate metabolism and gene expression including that associated with anti-oxidant activity. Their concentration, and hence availability, increases in diabetes mellitus and heart failure. Whilst known to be substrates for ATP production, especially in starvation, their role(s) in the heart, and in heart disease, is uncertain. Recent evidence, reviewed here, indicates that increased ketone body metabolism is a feature of heart failure, and is accompanied by other changes in substrate selection. Whether the change in myocardial ketone body metabolism is adaptive or maladaptive is unknown, but it offers the possibility of using exogenous ketones to treat the failing heart.
Topics: Acetoacetates; Fatty Acids; Glucose; Heart Failure; Humans; Ketone Bodies; Ketones; Myocardium
PubMed: 32084511
DOI: 10.1016/j.bbadis.2020.165739 -
Journal of Cellular Physiology Dec 2017Dairy cows with ketosis are characterized by oxidative stress, hepatic damage, and hyperketonemia. Acetoacetate (AA) is the main component of ketone bodies in ketotic...
Dairy cows with ketosis are characterized by oxidative stress, hepatic damage, and hyperketonemia. Acetoacetate (AA) is the main component of ketone bodies in ketotic cows, and is associated with the above pathological process. However, the potential mechanism was not illuminated. Therefore, the aim of this study was to investigate the mechanism of AA-induced hepatic oxidative damage in ketotic cows. Compared with healthy cows, ketotic cows exhibited severe oxidative stress and hepatic damage. Moreover, the extent of hepatic damage and oxidative stress had a positive relationship with the AA levels. In vitro, AA treatment increased reactive oxygen species (ROS) content and further induced oxidative stress and apoptosis of bovine hepatocytes. In this process, AA treatment increased the phosphorylation levels of JNK and p38MAPK and decreased the phosphorylation level of ERK, which could increase p53 and inhibit nuclear factor E2-related factor 2 (Nrf2) expression, nuclear localization, and DNA-binding affinity, thereby inducing the overexpression of pro-apoptotic molecules Bax, Caspase 3, Caspase 9, PARP and inhibition of anti-apoptotic molecule Bcl-2. Antioxidant N-acetylcysteine (NAC) treatment or interference of MAPKs pathway could attenuate the hepatocytes apoptosis induced by AA. Collectively, these results indicate that AA triggers hepatocytes apoptosis via the ROS-mediated MAPKs pathway in ketotic cows.
Topics: Acetoacetates; Animals; Apoptosis; Cattle; Cells, Cultured; Female; Hepatocytes; Ketosis; MAP Kinase Signaling System; Oxidative Stress; Reactive Oxygen Species
PubMed: 28059455
DOI: 10.1002/jcp.25773