Metabolic Flexibility as an Adaptation to Energy Resources and Requirements in Health and Disease

Chronic cold stress promotes inflammation and ER stress via inhibiting GLP-1R signaling, and exacerbates the risk of ferroptosis in the liver and pancreas

The cold climates in autumn and winter threatens human health. The aim of this study was to reveal the effects of prolonged cold exposure on the liver and pancreas based on GLP-1R signaling, oxidative stress, endoplasmic reticulum (ER) stress and ferroptosis by Yorkshire pig models. Yorkshire pigs were divided into the control group and chronic cold stress (CCS) group. The results showed that CCS induced oxidative stress injury, activated Nrf2 pathway and inhibited the expression of GLP-1R in the liver and pancreas (P < 0.05). The toll-like receptor 4 (TLR4) pathway was activated in the liver and pancreas, accompanied by the enrichment of IL-1β and TNF-α during CCS (P < 0.05). Moreover, the kinase RNA-like endoplasmic reticulum kinase (PERK), inositol requiring kinase 1 (IRE1), X-box-binding protein 1 (XBP1) and eukaryotic initiation factor 2α (eIF2α) expression in the liver and pancreas was up-regulated during CCS (P < 0.05). In addition, CCS promoted the prostaglandin-endoperoxide synthase 2 (PTGS2) expression and inhibited the ferritin H (FtH) expression in the liver. Summarily, CCS promotes inflammation, ER stress and apoptosis by inhibiting the GLP-1R signaling and inducing oxidative stress, and exacerbates the risk of ferroptosis in the liver and pancreas.

Elucidating the effective age for dietary restriction and the key metabolites involved

Dietary restriction (DR) extends lifespan in various species, but its effect at different ages, especially when started later, is unclear. This study used Caenorhabditis elegans to explore the impact of DR at different ages. Worms were divided into control and DR groups, with daily survival monitored. To confirm the occurrence of DR, the expression of DR-sensitive genes namely acdh-1, pyk-1, pck-2 and cts-1 were determined using RT-qPCR. Liquid chromatography mass spectrometry (LC-MS) was employed to observe the changes in metabolites affected by DR. The results indicated that young worms subjected to mild DR displayed the longest lifespan, highlighting the effectiveness of initiating DR at a young age. Increased expression of acdh-1 and pck-2 suggests activation of beta-oxidation and gluconeogenesis, while decreased cts-1 expression indicates a reduced citric acid cycle, further supporting the observed effects of DR in these worms. Metabolomic results indicated that DR decreased the activity of mechanistic Target of Rapamycin (mTOR) and the synthesis of amino acids namely leucine, tyrosine and tryptophan to conserve energy for cell repair and survival. DR also decreased levels of N-acetyl-L-methionine and S-adenosyl-methionine (SAM) in methionine metabolism, thereby promoting autophagy, reducing inflammation, and facilitating the removal of damaged cells and proteins. In conclusion, initiating dietary restriction early in life extends the lifespan by modulating amino acid metabolism and enhancing the autophagy pathway, thereby maintaining cellular wellbeing.

Skeletal muscle p53-depletion uncovers a mechanism of fuel usage suppression that enables efficient energy conservation

BACKGROUND

The ability of skeletal muscle to respond adequately to changes in nutrient availability, known as metabolic flexibility, is essential for the maintenance of metabolic health and loss of flexibility contributes to the development of diabetes and obesity. The tumour suppressor protein, p53, has been linked to the control of energy metabolism. We assessed its role in the acute control of nutrient allocation in skeletal muscle in the context of limited nutrient availability.

METHODS

A mouse model with inducible deletion of the p53-encoding gene, Trp53, in skeletal muscle was generated using the Cre-loxP-system. A detailed analysis of nutrient metabolism in mice with control and knockout genotypes was performed under ad libitum fed and fasting conditions and in exercised mice.

RESULTS

Acute deletion of p53 in myofibres of mice activated catabolic nutrient usage pathways even under ad libitum fed conditions, resulting in significantly increased overall energy expenditure (+10.6%; P = 0.0385) and a severe nutrient deficit in muscle characterized by depleted intramuscular glucose and glycogen levels (-62,0%; P < 0.0001 and -52.7%; P < 0.0001, respectively). This was accompanied by changes in marker gene expression patterns of circadian rhythmicity and hyperactivity (+57.4%; P = 0.0068). These metabolic changes occurred acutely, within 2-3 days after deletion of Trp53 was initiated, suggesting a rapid adaptive response to loss of p53, which resulted in a transient increase in lactate release to the circulation (+46.6%; P = 0.0115) from non-exercised muscle as a result of elevated carbohydrate mobilization. Conversely, an impairment of proteostasis and amino acid metabolism was observed in knockout mice during fasting. During endurance exercise testing, mice with acute, muscle-specific Trp53 inactivation displayed an early exhaustion phenotype with a premature shift in fuel usage and reductions in multiple performance parameters, including a significantly reduced running time and distance (-13.8%; P = 0.049 and -22.2%; P = 0.0384, respectively).

CONCLUSIONS

These findings suggest that efficient nutrient conservation is a key element of normal metabolic homeostasis that is sustained by p53. The homeostatic state in metabolic tissues is actively maintained to coordinate efficient energy conservation and metabolic flexibility towards nutrient stress. The acute deletion of Trp53 unlocks mechanisms that suppress the activity of nutrient catabolic pathways, causing substantial loss of intramuscular energy stores, which contributes to a fasting-like state in muscle tissue. Altogether, these findings uncover a novel function of p53 in the short-term regulation of nutrient metabolism in skeletal muscle and show that p53 serves to maintain metabolic homeostasis and efficient energy conservation.

Modeling sex-specific whole-body metabolic responses to feeding and fasting

Men generally favor carbohydrate metabolism, while women lean towards lipid metabolism, resulting in significant sex-based differences in energy oxidation across various metabolic states such as fasting and feeding. These differences are influenced by body composition and inherent metabolic fluxes, including increased lipolysis rates in women. However, understanding how sex influences organ-specific metabolism and systemic manifestations remains incomplete. To address these gaps, we developed a sex-specific, whole-body metabolic model for feeding and fasting scenarios in healthy young adults. Our model integrates organ metabolism with whole-body responses to mixed meals, particularly high-carbohydrate and high-fat meals. Our predictions suggest that differences in liver and adipose tissue nutrient storage and oxidation patterns drive systemic metabolic disparities. We propose that sex differences in fasting hepatic glucose output may result from the different handling of free fatty acids, glycerol, and glycogen. We identified a metabolic pathway, possibly more prevalent in female livers, redirecting lipids towards carbohydrate metabolism to support hepatic glucose production. This mechanism is facilitated by the TG-FFA cycle between adipose tissue and the liver. Incorporating sex-specific data into multi-scale frameworks offers insights into how sex modulates human metabolism.

Oxidized Carbon Nanoparticles Enhance Cellular Energetics With Application to Injured Brain

Pro-energetic effects of functionalized, oxidized carbon nanozymes (OCNs) are reported. OCNs, derived from harsh acid oxidation of single-wall carbon nanotubes or activated charcoal are previously shown to possess multiple nanozymatic activities including mimicking superoxide dismutase and catalyzing the oxidation of reduced nicotinamide adenine dinucleotide (NADH) to NAD+. These actions are predicted to generate a glycolytic shift and enhance mitochondrial energetics under impaired conditions. Impaired mitochondrial energy metabolism is increasingly recognized as an important facet of traumatic brain injury (TBI) pathophysiology and decreases the efficiency of electron transport chain (ETC)-coupled adenosine triphosphate (ATP) and NAD+ regeneration. In vitro, OCNs promote a pro-aerobic shift in energy metabolism that persists through ETC inhibition and enhances glycolytic flux, glycolytic ATP production, and cellular generation of lactate, a crucial auxiliary substrate for energy metabolism. To address specific mechanisms of iron injury from hemorrhage, OCNs with the iron chelator, deferoxamine (DEF), covalently-linked were synthesized. DEF-linked OCNs induce a glycolytic shift in-vitro and in-vivo in tissue sections from a rat model of TBI complicated by hemorrhagic contusion. OCNs further reduced hemorrhage volumes 3 days following TBI. These results suggest OCNs are promising as pleiotropic mediators of cell and tissue resilience to injury.

The effect of aerobic and high-intensity interval training on plasma pentraxin 3 and lipid parameters in overweight and obese women

Background

It is unclear whether different exercise programs lead to an increase in the concentration of plasma Pentraxin3 (PTX3), an anti-inflammatory protein. This study aimed to investigate the effects of aerobic exercise (AE) and high-intensity interval training (HIIT) on plasma PTX3 levels in overweight and obese women.

Method

A total of 45 sedentary women aged between 32.26 ± 6.30 voluntarily participated in the study. The control group (CG, n = 15) was selected among normal-weight women. Women in the group of participants who partook in exercise consisted of overweight and obese women according to a random method, including the AE group (n = 15) and the HIIT group (n = 15). The AE session conducted was 50 min in duration and consisted of warm-up exercises (5 min), and primary exercises (40 min, basic aerobic-step exercises). HIIT consists of warm-up exercises (5 min), primary exercises (work intervals: 6-10 × 1 min (80-90% HRmax), rest intervals: 1 min (walk, 50% HRmax), 21-29 min running. The exercises were applied for three sessions/week for 12 weeks. Fasting blood samples were taken from all participants before and after exercise and their body composition was measured.

Results

As a result of two different 12-week exercises, serum PTX3 levels increased significantly by 47.53% in the AE group and 50.21% in the HIIT group (p < 0.01). It was determined that the mean PTX3 before and after exercise increased from 1.71 ± 0.43 to 2.47 ± 0.40 ng/dL and HIIT from 1.62 ± 0.39 to 2.31 ± 0.33 ng/dL. A significant decrease in body mass index (BMI) values were detected, approximately 5.81% in the AE group and 5.06% in the HIIT group (p < .01). A significant decrease was detected in glucose, insulin, HOMA-IR, LDL-C, and hsCRP whereas HDL-C and VO2max value increased significantly in both exercise groups (p < .05; p < .01). There were no significant differences in TG and TC levels between groups (p > .05). Also, no significant differences were found between the two types of exercises in terms of parameters. A significant negative correlation in the total sample was found between PTX3 with BMI, fat mass, LDL-C, and hsCRP.

Conclusion

The percentage change in PTX3 values was not different between exercise types, whereas PTX3 was increased with exercise, regardless of the type of exercise. It can be said that both aerobic and HIIT increase PTX3, VO2max levels and improve lipid metabolism in overweight and obese women.

Unraveling the Mystery of Energy-Sensing Enzymes and Signaling Pathways in Tumorigenesis and Their Potential as Therapeutic Targets for Cancer

Cancer research has advanced tremendously with the identification of causative genes, proteins, and signaling pathways. Numerous antitumor drugs have been designed and screened for cancer therapeutics; however, designing target-specific drugs for malignant cells with minimal side effects is challenging. Recently, energy-sensing- and homeostasis-associated molecules and signaling pathways playing a role in proliferation, apoptosis, autophagy, and angiogenesis have received increasing attention. Energy-metabolism-based studies have shown the contribution of energetics to cancer development, where tumor cells show increased glycolytic activity and decreased oxidative phosphorylation (the Warburg effect) in order to obtain the required additional energy for rapid division. The role of energy homeostasis in the survival of normal as well as malignant cells is critical; therefore, fuel intake and expenditure must be balanced within acceptable limits. Thus, energy-sensing enzymes detecting the disruption of glycolysis, AMP, ATP, or GTP levels are promising anticancer therapeutic targets. Here, we review the common energy mediators and energy sensors and their metabolic properties, mechanisms, and associated signaling pathways involved in carcinogenesis, and explore the possibility of identifying drugs for inhibiting the energy metabolism of tumor cells. Furthermore, to corroborate our hypothesis, we performed meta-analysis based on transcriptomic profiling to search for energy-associated biomarkers and canonical pathways.

Metabolic phenotypes reflect patient sex and injury status: A cross-sectional analysis of human synovial fluid

OBJECTIVE

Osteoarthritis is a heterogeneous disease. The objective was to compare differences in underlying cellular mechanisms and endogenous repair pathways between synovial fluid (SF) from male and female participants with different injuries to improve the current understanding of the pathophysiology of downstream post-traumatic osteoarthritis (PTOA).

DESIGN

SF from n = 33 knee arthroscopy patients between 18 and 70 years with no prior knee injuries was obtained pre-procedure and injury pathology assigned post-procedure. SF was extracted and analyzed via liquid chromatography-mass spectrometry metabolomic profiling to examine differences in metabolism between injury pathologies (ligament, meniscal, and combined ligament and meniscal) and patient sex. Samples were pooled and underwent secondary fragmentation to identify metabolites.

RESULTS

Different knee injuries uniquely altered SF metabolites and downstream pathways including amino acid, lipid, and inflammatory-associated metabolic pathways. Notably, sexual dimorphic metabolic phenotypes were examined between males and females and within injury pathology. Cervonyl carnitine and other identified metabolites differed in concentrations between sexes.

CONCLUSIONS

These results suggest that different injuries and patient sex are associated with distinct metabolic phenotypes. Considering these phenotypic associations, a greater understanding of metabolic mechanisms associated with specific injuries, sex, and PTOA development may yield data regarding how endogenous repair pathways differ between male and female injury types. Ongoing metabolomic analysis of SF in injured male and female patients can be performed to monitor PTOA development and progression.

Intermittent fasting influences immunity and metabolism

Intermittent fasting (IF) modifies cell- and tissue-specific immunometabolic responses that dictate metabolic flexibility and inflammation during obesity and type 2 diabetes (T2D). Fasting forces periods of metabolic flexibility and necessitates increased use of different substrates. IF can lower metabolic inflammation and improve glucose metabolism without lowering obesity and can influence time-dependent, compartmentalized changes in immunity. Liver, adipose tissue, skeletal muscle, and immune cells communicate to relay metabolic and immune signals during fasting. Here we review the connections between metabolic and immune cells to explain the divergent effects of IF compared with classic caloric restriction (CR) strategies. We also explore how the immunometabolism of metabolic diseases dictates certain IF outcomes, where the gut microbiota triggers changes in immunity and metabolism during fasting.

Human inborn errors of long-chain fatty acid oxidation show impaired inflammatory responses to TLR4-ligand LPS

Stimulation of mammalian cells with inflammatory inducers such as lipopolysaccharide (LPS) leads to alterations in activity of central cellular metabolic pathways. Interestingly, these metabolic changes seem to be important for subsequent release of pro-inflammatory cytokines. This has become particularly clear for enzymes of tricarboxylic acid (TCA) cycle such as succinate dehydrogenase (SDH). LPS leads to inhibition of SDH activity and accumulation of succinate to enhance the LPS-induced formation of IL-1β. If enzymes involved in beta-oxidation of fatty acids are important for sufficient responses to LPS is currently not clear. Using cells from various patients with inborn long-chain fatty acid oxidation disorders (lcFAOD), we report that disease-causing deleterious variants of Electron Transfer Flavoprotein Dehydrogenase (ETFDH) and of Very Long Chain Acyl-CoA Dehydrogenase (ACADVL), both cause insufficient inflammatory responses to stimulation with LPS. The insufficiencies included reduced TLR4 expression levels, impaired TLR4 signaling, and reduced or absent induction of pro-inflammatory cytokines such as IL-6. The insufficient responses to LPS were reproduced in cells from healthy controls by targeted loss-of-function of either ETFDH or ACADVL, supporting that the deleterious ETFDH and ACADVL variants cause the attenuated responses to LPS. ETFDH and ACADVL encode two distinct enzymes both involved in fatty acid beta-oxidation, and patients with these deficiencies cannot sufficiently metabolize long-chain fatty acids. We report that genes important for beta-oxidation of long-chain fatty acids are also important for inflammatory responses to an acute immunogen trigger like LPS, which may have important implications for understanding infection and other metabolic stress induced disease pathology in lcFAODs.

Overview of a novel osmotin abolishes abnormal metabolic-associated adiponectin mechanism in Alzheimer's disease: Peripheral and CNS insights

Alzheimer's disease (AD) is a degenerative brain disease that affects millions of people worldwide. It is caused by abnormalities in cholinergic neurons, oxidative stress, and inflammatory cascades. The illness is accompanied by personality changes, memory issues, and dementia. Metabolic signaling pathways help with fundamental processes like DNA replication and RNA transcription. Being adaptable is essential for both surviving and treating illness. The body's metabolic signaling depends on adipokines, including adiponectin (APN) and other adipokines secreted by adipose tissues. Energy homeostasis is balanced by adipokines, and nutrients. Overconsumption of nutrients messes with irregular signaling of adipokines, such as APN in both peripheral and brain which leads to neurodegeneration, such as AD. Despite the failure of traditional treatments like memantine and cholinesterase inhibitors, natural plant bioactive substances like Osmotin (OSM) have been given a focus as potential therapeutics due to their antioxidant properties, better blood brain barrier (BBB) permeability, excellent cell viability, and especially nanoparticle approaches. The review highlights the published preclinical literature regarding the role of OSM in AD pathology while there is a need for more research to investigate the hidden therapeutic potential of OSM which may open a new gateway and further strengthen its healing role in the pathogenesis of neurodegeneration, especially AD.

Maternal high fat-high energy diet alters metabolic factors in the non-human primate fetal heart

The consumption of high fat-high energy diets (HF-HEDs) continues to rise worldwide and parallels the rise in maternal obesity (MO) that predisposes offspring to cardiometabolic disorders. Although the underlying mechanisms are unclear, thyroid hormones (TH) modulate cardiac maturation in utero. Therefore, we aimed to determine the impact of a high fat-high energy diet (HF-HED) on the hormonal, metabolic and contractility profile of the non-human primate (NHP) fetal heart. At ∼9 months preconception, female baboons (Papio hamadryas) were randomly assigned to either a control diet or HF-HED. At 165 days gestational age (term = 184 days), fetuses were delivered by Caesarean section under anaesthesia, humanely killed, and left ventricular cardiac tissue (Control (n = 6 female, 6 male); HF-HED (n = 6 F, 6 M)) was collected. Maternal HF-HED decreased the concentration of active cardiac TH (i.e. triiodothyronine (T3)), and type 1 iodothyronine deiodinase (DIO1) mRNA expression. Maternal HF-HED decreased the abundance of cardiac markers of insulin-mediated glucose uptake phosphorylated insulin receptor substrate 1 (Ser789) and glucose transporter 4, and increased protein abundance of key oxidative phosphorylation complexes (I, III, IV) and mitochondrial abundance in both sexes. Maternal HF-HED alters cardiac TH status, which may induce early signs of cardiac insulin resistance. This may increase the risk of cardiometabolic disorders in later life in offspring born to these pregnancies. KEY POINTS: Babies born to mothers who consume a high fat-high energy diet (HF-HED) prior to and during pregnancy are predisposed to an increased risk of cardiometabolic disorders across the life course. Maternal HF-HED prior to and during pregnancy decreased thyroid hormone triiodothyronine (T3) concentrations and type 1 iodothyronine deiodinase DIO1 mRNA expression in the non-human primate fetal heart. Maternal HF-HED decreased markers of insulin-dependent glucose uptake, phosphorylated insulin receptor substrate 1 and glucose transporter 4 in the fetal heart. Maternal HF-HED increased mitochondrial abundance and mitochondrial OXPHOS complex I, III and IV in the fetal heart. Fetuses from HF-HED pregnancies are predisposed to cardiometabolic disorders that may be mediated by changes in T3, placing them on a poor lifetime cardiovascular health trajectory.

A Systematic Review of Proteomics in Obesity: Unpacking the Molecular Puzzle

PURPOSE OF REVIEW

The present study aims to review the existing literature to identify pathophysiological proteins in obesity by conducting a systematic review of proteomics studies. Proteomics may reveal the mechanisms of obesity development and clarify the links between obesity and related diseases, improving our comprehension of obesity and its clinical implications.

RECENT FINDINGS

Most of the molecular events implicated in obesity development remain incomplete. Proteomics stands as a powerful tool for elucidating the intricate interactions among proteins in the context of obesity. This methodology has the potential to identify proteins involved in pathological processes and to evaluate changes in protein abundance during obesity development, contributing to the identification of early disease predisposition, monitoring the effectiveness of interventions and improving disease management overall. Despite many non-targeted proteomic studies exploring obesity, a comprehensive and up-to-date systematic review of the molecular events implicated in obesity development is lacking. The lack of such a review presents a significant challenge for researchers trying to interpret the existing literature. This systematic review was conducted following the PRISMA guidelines and included sixteen human proteomic studies, each of which delineated proteins exhibiting significant alterations in obesity. A total of 41 proteins were reported to be altered in obesity by at least two or more studies. These proteins were involved in metabolic pathways, oxidative stress responses, inflammatory processes, protein folding, coagulation, as well as structure/cytoskeleton. Many of the identified proteomic biomarkers of obesity have also been reported to be dysregulated in obesity-related disease. Among them, seven proteins, which belong to metabolic pathways (aldehyde dehydrogenase and apolipoprotein A1), the chaperone family (albumin, heat shock protein beta 1, protein disulfide-isomerase A3) and oxidative stress and inflammation proteins (catalase and complement C3), could potentially serve as biomarkers for the progression of obesity and the development of comorbidities, contributing to personalized medicine in the field of obesity. Our systematic review in proteomics represents a substantial step forward in unravelling the complexities of protein alterations associated with obesity. It provides valuable insights into the pathophysiological mechanisms underlying obesity, thereby opening avenues for the discovery of potential biomarkers and the development of personalized medicine in obesity.

Fat burning capacity in a mixed macronutrient meal protocol does not reflect metabolic flexibility in women who are overweight or obese

Introduction

Metabolic flexibility, the ability to switch from glucose to fat as a fuel source, is considered a marker of metabolic health. Higher fat oxidation is often associated with greater flexibility and insulin sensitivity, while lower fat oxidation is linked to metabolic inflexibility and insulin resistance. However, our study challenges the universal validity of this relationship, uncovering a more nuanced understanding of the complex interplay between fuel source switching and fat oxidation, especially in the presence of insulin resistance.

Methods

In an 8-week controlled feeding intervention, overweight to obese women with insulin resistance (as defined by McAuley's index) were randomized to consume either a diet based on the Dietary Guidelines for Americans 2010 (DGA) or a 'Typical' American Diet (TAD), n = 22 each. Participants were given a high-fat mixed macronutrient challenge test (MMCT) (60% fat, 28% carbohydrates, and 12% protein) at weeks 0, 2, and 8. Plasma lipids, metabolome, and lipidome were measured at 0, 0.5, 3, and 6h postprandial (PP); substrate oxidation measures were also recorded at 0,1 3, and 6h PP. Metabolic flexibility was evaluated as the change in fat oxidation from fasting to PP. Mixed model and multivariate analyses were used to evaluate the effect of diet on these outcomes, and to identify variables of interest to metabolic flexibility.

Results

Intervention diets (DGA and TAD) did not differentially affect substrate oxidation or metabolic flexibility, and equivalence tests indicated that groups could be combined for subsequent analyses. Participants were classified into three groups based on the % of consumed MMCT fat was oxidized in the 6h post meal period at weeks 0, 2 and 8. Low fat burners (LB, n = 6, burned <30% of fat in MMCT) and high fat burners (HB, n = 7, burned > 40% of fat in MMCT) at all weeks. Compared to LB, HB group had higher fat mass, total mass, lean mass, BMI, lower HDLc and lower RER (p < 0.05), but not different % body fat or % lean mass. During week 0, at 1h PP, LB had an increase in % fat oxidation change from 0h compared to HB (p<0.05), suggesting higher metabolic flexibility. This difference disappeared later in the PP phase, and we did not detect this beyond week 0. Partial least squares discriminant analysis (PLSDA (regular and repeated measures (sPLSDA)) models identified that LB group, in the late PP phase, was associated with higher rates of disappearance of acylcarnitines (AC) and lysophosphatidylcholines (LPC) from plasma (Q2: 0.20, R2X: 0.177, R2Y: 0.716).

Conclusion

In women with insulin resistance, a high fat burning capacity does not imply high metabolic flexibility, and not all women with insulin resistance are metabolically inflexible. LPCs and ACs are promising biomarkers of metabolic flexibility.

Diet and physical exercise as key players to tackle MASLD through improvement of insulin resistance and metabolic flexibility

Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) has emerged as a prevalent health concern, encompassing a wide spectrum of liver-related disorders. Insulin resistance, a key pathophysiological feature of MASLD, can be effectively ameliorated through dietary interventions. The Mediterranean diet, rich in whole grains, fruits, vegetables, legumes, and healthy fats, has shown promising results in improving insulin sensitivity. Several components of the Mediterranean diet, such as monounsaturated fats and polyphenols, exert anti-inflammatory and antioxidant effects, thereby reducing hepatic steatosis and inflammation. Furthermore, this dietary pattern has been associated with a higher likelihood of achieving MASLD remission. In addition to dietary modifications, physical exercise, particularly resistance exercise, plays a crucial role in enhancing metabolic flexibility. Resistance exercise training promotes the utilization of fatty acids as an energy source. It enhances muscle glucose uptake and glycogen storage, thus reducing the burden on the liver to uptake excess blood glucose. Furthermore, resistance exercise stimulates muscle protein synthesis, contributing to an improved muscle-to-fat ratio and overall metabolic health. When implemented synergistically, the Mediterranean diet and resistance exercise can elicit complementary effects in combating MASLD. Combined interventions have demonstrated additive benefits, including greater improvements in insulin resistance, increased metabolic flexibility, and enhanced potential for MASLD remission. This underscores the importance of adopting a multifaceted approach encompassing dietary modifications and regular physical exercise to effectively manage MASLD. This narrative review explores the biological mechanisms of diet and physical exercise in addressing MASLD by targeting insulin resistance and decreased metabolic flexibility.

microRNA-1 Regulates Metabolic Flexibility in Skeletal Muscle via Pyruvate Metabolism

MicroRNA-1 (miR-1) is the most abundant miRNA in adult skeletal muscle. To determine the function of miR-1 in adult skeletal muscle, we generated an inducible, skeletal muscle-specific miR-1 knockout (KO) mouse. Integration of RNA-sequencing (RNA-seq) data from miR-1 KO muscle with Argonaute 2 enhanced crosslinking and immunoprecipitation sequencing (AGO2 eCLIP-seq) from human skeletal muscle identified miR-1 target genes involved with glycolysis and pyruvate metabolism. The loss of miR-1 in skeletal muscle induced cancer-like metabolic reprogramming, as shown by higher pyruvate kinase muscle isozyme M2 (PKM2) protein levels, which promoted glycolysis. Comprehensive bioenergetic and metabolic phenotyping combined with skeletal muscle proteomics and metabolomics further demonstrated that miR-1 KO induced metabolic inflexibility as a result of pyruvate oxidation resistance. While the genetic loss of miR-1 reduced endurance exercise performance in mice and in C. elegans, the physiological down-regulation of miR-1 expression in response to a hypertrophic stimulus in both humans and mice causes a similar metabolic reprogramming that supports muscle cell growth. Taken together, these data identify a novel post-translational mechanism of adult skeletal muscle metabolism regulation mediated by miR-1.

L-carnitine: A novel approach in management of acute cholinesterase inhibitor insecticide poisoning

Cholinesterase inhibitors (ChEIs) insecticide poisoning is a serious global health concern that results in hundreds of thousands of fatalities each year. Although inhibition of the cholinesterase enzyme is the main mechanism of ChEI poisoning, oxidative stress is considered the mechanism underlying the related complications. The study aimed to assess the oxidative status of the patients with ChEI insecticide poisoning and the role of L-carnitine as adjuvant therapy in their management. Human studies on the efficacy and safety of L-carnitine in treating insecticide poisoning are limited despite its growing research interest as a safe antioxidant. This prospective study was conducted on eighty patients with acute ChEIs insecticide poisoning admitted to Alexandria Poison Center, Alexandria Main University Hospital, Egypt. Patients were allocated into two equal groups randomly. The L-carnitine (LC) group received the conventional treatment (atropine & toxogonin) and LC and the standard treatment (ST) group received the standard treatment only. Outcome measures were fatality rate, the total administered dose of atropine & toxogonin, length of hospital stay, and the requirement for ICU admission or mechanical ventilation. The study results revealed that malondialdehyde (MDA) significantly decreased in the LC group. Cholinesterase enzyme levels increased significantly after treatment in the LC group than in the ST group. The LC group needed lower dosages of atropine and toxogonin than the ST group. Also, the LC group showed no need for ICU admission or mechanical ventilation. The study concluded that LC can be considered a promising adjuvant antioxidant treatment in acute ChEIs pesticide poisoning.

Nutritional Mechanisms of Cancer Cachexia

Cancer cachexia is a complex systemic wasting syndrome. Nutritional mechanisms that span energy intake, nutrient metabolism, body composition, and energy balance may be impacted by, and may contribute to, the development of cachexia. To date, clinical management of cachexia remains elusive. Leaning on discoveries and novel methodologies from other fields of research may bolster new breakthroughs that improve nutritional management and clinical outcomes. Characteristics that compare and contrast cachexia and obesity may reveal opportunities for cachexia research to adopt methodology from the well-established field of obesity research. This review outlines the known nutritional mechanisms and gaps in the knowledge surrounding cancer cachexia. In parallel, we present how obesity may be a different side of the same coin and how obesity research has tackled similar research questions. We present insights into how cachexia research may utilize nutritional methodology to expand our understanding of cachexia to improve definitions and clinical care in future directions for the field.

Intramammary lipopolysaccharide challenge in early- versus mid-lactation dairy cattle: Immune, production, and metabolic responses

Study objectives were to compare the immune response, metabolism, and production following intramammary LPS (IMM LPS) administration in early and mid-lactation cows. Early (E-LPS; n = 11; 20 ± 4 DIM) and mid- (M-LPS; n = 10; 155 ± 40 DIM) lactation cows were enrolled in an experiment consisting of 2 periods (P). During P1 (5 d) cows were fed ad libitum and baseline data were collected, including liver and muscle biopsies. At the beginning of P2 (3 d) cows received 10 mL of sterile saline containing 10 µg of LPS from Escherichia coli O111:B4/mL into the left rear quarter of the mammary gland, and liver and muscle biopsies were collected at 12 h after LPS. Tissues were analyzed for metabolic flexibility, which measures substrate switching capacity from pyruvic acid to palmitic acid oxidation. Data were analyzed with the MIXED procedure in SAS 9.4. Rectal temperature was assessed hourly for the first 12 h after LPS and every 6 h thereafter for the remainder of P2. All cows developed a febrile response following LPS, but E-LPS had a more intense fever than M-LPS cows (0.7°C at 5 h after LPS). Blood samples were collected at 0, 3, 6, 9, 12, 24, 36, 48, and 72 h after LPS for analysis of systemic inflammation and metabolism parameters. Total serum Ca decreased after LPS (26% at 6 h nadir) but did not differ by lactation stage (LS). Circulating neutrophils decreased, then increased after LPS in both LS, but E-LPS had exaggerated neutrophilia (56% from 12 to 48 h) compared with M-LPS. Haptoglobin increased after LPS (15-fold) but did not differ by LS. Many circulating cytokines were increased after LPS, and IL-6, IL-10, TNF-α, MCP-1, and IP-10 were further augmented in E-LPS compared with M-LPS cows. Relative to P1, all cows had reduced milk yield (26%) and DMI (14%) on d 1 that did not differ by LS. Somatic cell score increased rapidly in response to LPS regardless of LS and gradually decreased from 18 h onwards. Milk component yields decreased after LPS. However, E-LPS had increased fat (11%) and tended to have increased lactose (8%) yield compared with M-LPS cows throughout P2. Circulating glucose was not affected by LPS. Nonesterified fatty acids (NEFA) decreased in E-LPS (29%) but not M-LPS cows. β-Hydroxybutyrate slightly increased (14%) over time after LPS regardless of LS. Insulin increased after LPS in all cows, but E-LPS had blunted hyperinsulinemia (52%) compared with M-LPS cows. Blood urea nitrogen increased after LPS, and the relative change in BUN was elevated in E-LPS cows compared with M-LPS cows (36% and 13%, respectively, from 9 to 24 h). During P1, metabolic flexibility was increased in liver and muscle in early lactating cows compared with mid-lactation cows, but 12 h after LPS, metabolic flexibility was reduced and did not differ by LS. In conclusion, IMM LPS caused severe immune activation, and E-LPS cows had a more intense inflammatory response compared with M-LPS cows, but the effects on milk synthesis was similar between LS. Some parameters of the E-LPS metabolic profile suggest continuation of metabolic adjustments associated with early lactation to support both a robust immune system and milk synthesis.

Ammonia transporter RhBG initiates downstream signaling and functional responses by activating NFκB

Transceptors, solute transporters that facilitate intracellular entry of molecules and also initiate intracellular signaling events, have been primarily studied in lower-order species. Ammonia, a cytotoxic endogenous metabolite, is converted to urea in hepatocytes for urinary excretion in mammals. During hyperammonemia, when hepatic metabolism is impaired, nonureagenic ammonia disposal occurs primarily in skeletal muscle. Increased ammonia uptake in skeletal muscle is mediated by a membrane-bound, 12 transmembrane domain solute transporter, Rhesus blood group-associated B glycoprotein (RhBG). We show that in addition to its transport function, RhBG interacts with myeloid differentiation primary response-88 (MyD88) to initiate an intracellular signaling cascade that culminates in activation of NFκB. We also show that ammonia-induced MyD88 signaling is independent of the canonical toll-like receptor-initiated mechanism of MyD88-dependent NFκB activation. In silico, in vitro, and in situ experiments show that the conserved cytosolic J-domain of the RhBG protein interacts with the Toll-interleukin-1 receptor (TIR) domain of MyD88. In skeletal muscle from human patients, human-induced pluripotent stem cell-derived myotubes, and myobundles show an interaction of RhBG-MyD88 during hyperammonemia. Using complementary experimental and multiomics analyses in murine myotubes and mice with muscle-specific RhBG or MyD88 deletion, we show that the RhBG-MyD88 interaction is essential for the activation of NFkB but not ammonia transport. Our studies show a paradigm of substrate-dependent regulation of transceptor function with the potential for modulation of cellular responses in mammalian systems by decoupling transport and signaling functions of transceptors.

Current advances in cancer energy metabolism under dietary restriction: a mini review

The manipulation of the energy or source of food for cancer cells has attracted significant attention in oncology research. Metabolic reprogramming of the immune system allows for a deeper understanding of cancer cell mechanisms, thereby impeding their progression. A more targeted approach is the restriction of cancer cells through dietary restriction (CR), which deprives cancer cells of the preferred energy sources within the tumor microenvironment, thereby enhancing immune cell efficacy. Although there is a plethora of CR strategies that can be employed to impede cancer progression, there is currently no comprehensive review that delineates the specific dietary restrictions that target the diverse metabolic pathways of cancer cells. This mini-review introduces amino acids as anti-cancer agents and discusses the role of dietary interventions in cancer prevention and treatment. It highlights the potential of a ketogenic diet as a therapeutic approach for cancer, elucidating its distinct mechanisms of action in tumor progression. Additionally, the potential of plant-based diets as anti-cancer agents and the role of polyphenols and vitamins in anti-cancer therapy were also discussed, along with some prospective interventions for CR as anti-tumor progression.

Intramuscular administration of fractalkine modulates mitochondrial properties and promotes fast glycolytic phenotype

A newly categorized myokine called fractalkine (CX3CL1) has been associated with divergent conditions such as obesity, tissue inflammation, and exercise. CX3CL1 works through specific membrane-bound receptors (CX3CR1) found in various tissues including skeletal muscles. Studies indicate CX3CL1 induces muscles to uptake energy substrates thereby improving glucose utilization and countering diabetes. Here, we tested if the administration of purified CX3CL1 directly into mice skeletal muscles affects its histoarchitecture, mitochondrial activity, and expression of metabolic proteins. We analyzed four muscles: two upper-limb (quadriceps, hamstrings) and two lower-limb (tibialis anterior, gastrocnemius), contralateral leg muscles were taken as controls. The effects of CX3CL1 treatment on histoarchitecture, mitochondrial activity, and expression of metabolic proteins in muscles were characterized. We used histochemical staining succinate dehydrogenase (SDH)/cytochrome c oxidase (COX), myosin ATPase, alkaline phosphatase (ALP) to evaluate the mitochondrial activity, fiber types, and vascularization in the muscles, respectively. Western blotting was used to evaluate the expression of proteins associated with mitochondrial metabolism (OXPHOS), glycolysis, and vascularization. Overall, this study indicates CX3CL1 primarily modulates mitochondrial metabolism and shifts substrate preference toward glucose in the skeletal muscle. Evidence also supports that CX3CL1 stimulates the relative composition of fast fiber types, influencing selection of energy substrates in the skeletal muscle.

Respiratory infection- and asthma-prone, low vaccine responder children demonstrate distinct mononuclear cell DNA methylation pathways

BACKGROUND

Infants with frequent viral and bacterial respiratory infections exhibit compromised immunity to routine immunizations. They are also more likely to develop chronic respiratory diseases in later childhood. This study investigated the feasibility of epigenetic profiling to reveal endotype-specific molecular pathways with potential for early identification and immuno-modulation. Peripheral blood mononuclear cells from respiratory infection allergy/asthma-prone (IAP) infants and non-infection allergy/asthma prone (NIAP) were retrospectively selected for genome-wide DNA methylation and single nucleotide polymorphism analysis. The IAP infants were enriched for the low vaccine responsiveness (LVR) phenotype (Fisher's exact p-value = 0.02).

RESULTS

An endotype signature of 813 differentially methylated regions (DMRs) comprising 238 lead CpG associations (FDR < 0.05) emerged, implicating pathways related to asthma, mucin production, antigen presentation and inflammasome activation. Allelic variation explained only a minor portion of this signature. Stimulation of mononuclear cells with monophosphoryl lipid A (MPL), a TLR agonist, partially reversed this signature at a subset of CpGs, suggesting the potential for epigenetic remodeling.

CONCLUSIONS

This proof-of-concept study establishes a foundation for precision endotyping of IAP children and highlights the potential for immune modulation strategies using adjuvants for future investigation.

Smoking cessation only partially reverses cardiac metabolic and structural remodeling in mice

AIMS

Active cigarette smoking is a major risk factor for chronic obstructive pulmonary disease that remains elevated after cessation. Skeletal muscle dysfunction has been well documented after smoking, but little is known about cardiac adaptations to cigarette smoking. The underlying cellular and molecular cardiac adaptations, independent of confounding lifestyle factors, and time course of reversibility by smoking cessation remain unclear. We hypothesized that smoking negatively affects cardiac metabolism and induces local inflammation in mice, which do not readily reverse upon 2-week smoking cessation.

METHODS

Mice were exposed to air or cigarette smoke for 14 weeks with or without 1- or 2-week smoke cessation. We measured cardiac mitochondrial respiration by high-resolution respirometry, cardiac mitochondrial density, abundance of mitochondrial supercomplexes by electrophoresis, and capillarization, fibrosis, and macrophage infiltration by immunohistology, and performed cardiac metabolome and lipidome analysis by mass spectrometry.

RESULTS

Mitochondrial protein, supercomplex content, and respiration (all p < 0.03) were lower after smoking, which were largely reversed within 2-week smoking cessation. Metabolome and lipidome analyses revealed alterations in mitochondrial metabolism, a shift from fatty acid to glucose metabolism, which did not revert to control upon smoking cessation. Capillary density was not different after smoking but increased after smoking cessation (p = 0.02). Macrophage infiltration and fibrosis (p < 0.04) were higher after smoking but did not revert to control upon smoking cessation.

CONCLUSIONS

While cigarette-impaired smoking-induced cardiac mitochondrial function was reversed by smoking cessation, the remaining fibrosis and macrophage infiltration may contribute to the increased risk of cardiovascular events after smoking cessation.

The association between the size of adipocyte-derived extracellular vesicles and fasting serum triglyceride-glucose index as proxy measures of adipose tissue insulin resistance in a rat model of early-stage obesity

Introduction

Obesity is a complex disease that predisposes individuals to cardiometabolic alterations. It leads to adipose tissue (AT) dysfunction, which triggers insulin resistance (IR). This suggests that people with obesity develop local IR first and systemic IR later. AT secretes extracellular vesicles, which may be physiopathologically associated with the development of IR. Our aim was to evaluate the effect of a high-fat diet on different parameters of adiposity in a rat model of early-stage obesity and to determine if these parameters are associated with markers of systemic IR. In addition, we sought to explore the relationship between fasting blood measures of IR (Triglycerides/High Density Lipoprotein-cholesterol [TAG/HDL-c] and Triglycerides-Glucose Index [TyG Index]) with the size of adipocyte-derived extracellular vesicles (adEV).

Methods

We used a model of diet-induced obesity for ten weeks in Wistar rats exposed to a high-fat diet. Final weight gain was analyzed by Dual X-ray absorptiometry. Visceral obesity was measured as epididymal AT weight. IR was evaluated with fasting TyG Index & TAG/HDL-c, and adEV were isolated from mature adipocytes on ceiling culture.

Results

In the high-fat diet group, glucose and triglyceride blood concentrations were higher in comparison to the control group (Log2FC, 0.5 and 1.5 times higher, respectively). The values for TyG Index and adEV size were different between the control animals and the high-fat diet group. Multiple linear regression analyses showed that adEV size can be significantly associated with the TyG Index value, when controlling for epididymal AT weight.

Conclusion

Our results show that lipid and glucose metabolism, as well as the size and zeta potential of adEV are already altered in early-stage obesity and that adEV size can be significantly associated with liver and systemic IR, estimated by TyG Index.

A small switch in perspective: Comparing weight loss by nutrient balance versus caloric balance

The establishment of a Caloric balance has been classically discussed as the means to induce weight loss. Recently, the idea of nutrient balance as opposed to Caloric balance has emerged as a better means to induce weight loss. This investigation compared differences in weight loss between a diet based on a nutrient balanced diet compared to a Caloric balance diet. 53 (27M/26F) active overfat individuals (30.7+/- 7.1 years) were randomly (matched for age, gender, training history) assigned within an 8-week intervention to follow either a self-selected diet (control) or a diet based on following a Caloric balance (%Cal/day) or a nutrient balance (g/kg/day) in conjunction with a periodized exercise regimen to determine effectiveness for each diet to induce weight loss. Nutrient balance group had significantly different changes (p < 0.05) in fat-free mass (2.26 (2.02, 2.49) kg versus 0.42 (-0.40, 1.24) kg) and fat mass (-5.96 (-5.34, -6.58) kg versus -4.08 (-3.92, -5.92) kg) relative to the Caloric balance group and was more effective at meeting nutritional requirements for protein (ES = 0.65 (0.48, 0.85)) and lipids (ES = 0.24 (-0.09, 0.98)) than the Caloric balance group. Nutrient balance was subjectively scored as easier to follow and more likely to be self-selected. Using a nutrient balance diet may be more effective at inducing beneficial body compositional changes and shows being a more self-selected dietary method when compared to a Caloric balance diet. Therefore, it may be a better choice for advice when offering treatments to those who are attempting to lose weight or maintain weight loss.

Impact of the delay in cryopreservation timing during biobanking procedures on human liver tissue metabolomics

The liver is a highly specialized organ involved in regulating systemic metabolism. Understanding metabolic reprogramming of liver disease is key in discovering clinical biomarkers, which relies on robust tissue biobanks. However, sample collection and storage procedures pose a threat to obtaining reliable results, as metabolic alterations may occur during sample handling. This study aimed to elucidate the impact of pre-analytical delay during liver resection surgery on liver tissue metabolomics. Patients were enrolled for liver resection during which normal tissue was collected and snap-frozen at three timepoints: before transection, after transection, and after analysis in Pathology. Metabolomics analyses were performed using 1H Nuclear Magnetic Resonance (NMR) and Liquid Chromatography-Mass Spectrometry (LC-MS). Time at cryopreservation was the principal variable contributing to differences between liver specimen metabolomes, which superseded even interindividual variability. NMR revealed global changes in the abundance of an array of metabolites, namely a decrease in most metabolites and an increase in β-glucose and lactate. LC-MS revealed that succinate, alanine, glutamine, arginine, leucine, glycerol-3-phosphate, lactate, AMP, glutathione, and NADP were enhanced during cryopreservation delay (all p<0.05), whereas aspartate, iso(citrate), ADP, and ATP, decreased (all p<0.05). Cryopreservation delays occurring during liver tissue biobanking significantly alter an array of metabolites. Indeed, such alterations compromise the integrity of metabolomic data from liver specimens, underlining the importance of standardized protocols for tissue biobanking in hepatology.

The paradox of fatty-acid β-oxidation in muscle insulin resistance: Metabolic control and muscle heterogeneity

The skeletal muscle is a metabolically heterogeneous tissue that plays a key role in maintaining whole-body glucose homeostasis. It is well known that muscle insulin resistance (IR) precedes the development of type 2 diabetes. There is a consensus that the accumulation of specific lipid species in the tissue can drive IR. However, the role of the mitochondrial fatty-acid β-oxidation in IR and, consequently, in the control of glucose uptake remains paradoxical: interventions that either inhibit or activate fatty-acid β-oxidation have been shown to prevent IR. We here discuss the current theories and evidence for the interplay between β-oxidation and glucose uptake in IR. To address the underlying intricacies, we (1) dive into the control of glucose uptake fluxes into muscle tissues using the framework of Metabolic Control Analysis, and (2) disentangle concepts of flux and catalytic capacities taking into account skeletal muscle heterogeneity. Finally, we speculate about hitherto unexplored mechanisms that could bring contrasting evidence together. Elucidating how β-oxidation is connected to muscle IR and the underlying role of muscle heterogeneity enhances disease understanding and paves the way for new treatments for type 2 diabetes.

Human MicroRNAs Modulated by Diet: A Scoping Review

Because of their role in regulating and fine-tuning gene expression in the posttranscriptional period, microRNA (miRNA) may represent a mediating factor that connects diet and metabolic regulation. Given the vast number of miRNAs and that modulations in miRNA happen in response to a variety of stimuli, a comprehensive registry of miRNAs impacted by diet and the food items that modulate them, would have utility in the identification of miRNA complements for analysis of diet interventions and in helping to establish linkages between the specific impacts of diet components. A scoping literature search of online databases (PubMed, SCOPUS, EMBASE, and Web of Science) was performed. Only studies in human populations, those that used a diet intervention or meal challenge, and those that measured miRNA profiles in the same subject at multiple time points were included. Of the 6167 studies screened, only 25 met the study criteria and were included in the review. Seven studies examined miRNA following a meal challenge, whereas 18 investigated miRNA following a sustained diet intervention. The results demonstrated that miRNA are modulated following a variety of diet interventions and that intensity of miRNA response is greater in metabolically healthy subjects. Heterogeneity in the intensity and length of the diet intervention, the study populations being observed, and the methodology through which target miRNA are identified contribute to a lack of comparability across studies. The findings of this review highlight the need for more study of miRNA responsiveness to intake and provide recommendations for future research.

Metabolic flexibility in postmenopausal women: Hormone replacement therapy is associated with higher mitochondrial content, respiratory capacity, and lower total fat mass

AIM

To investigate effects of hormone replacement therapy in postmenopausal women on factors associated with metabolic flexibility related to whole-body parameters including fat oxidation, resting energy expenditure, body composition and plasma concentrations of fatty acids, glucose, insulin, cortisol, and lipids, and for the mitochondrial level, including mitochondrial content, respiratory capacity, efficiency, and hydrogen peroxide emission.

METHODS

22 postmenopausal women were included. 11 were undergoing estradiol and progestin treatment (HT), and 11 were matched non-treated controls (CONT). Peak oxygen consumption, maximal fat oxidation, glycated hemoglobin, body composition, and resting energy expenditure were measured. Blood samples were collected at rest and during 45 min of ergometer exercise (65% VO2peak). Muscle biopsies were obtained at rest and immediately post-exercise. Mitochondrial respiratory capacity, efficiency, and hydrogen peroxide emission in permeabilized fibers and isolated mitochondria were measured, and citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase (HAD) activity were assessed.

RESULTS

HT showed higher absolute mitochondrial respiratory capacity and post-exercise hydrogen peroxide emission in permeabilized fibers and higher CS and HAD activities. All respiration normalized to CS activity showed no significant group differences in permeabilized fibers or isolated mitochondria. There were no differences in resting energy expenditure, maximal, and resting fat oxidation or plasma markers. HT had significantly lower visceral and total fat mass compared to CONT.

CONCLUSION

Use of hormone therapy is associated with higher mitochondrial content and respiratory capacity and a lower visceral and total fat mass. Resting energy expenditure and fat oxidation did not differ between HT and CONT.

Therapeutic targeting of white adipose tissue metabolic dysfunction in obesity: mechanisms and opportunities

White adipose tissue is not only a highly heterogeneous organ containing various cells, such as adipocytes, adipose stem and progenitor cells, and immune cells, but also an endocrine organ that is highly important for regulating metabolic and immune homeostasis. In individuals with obesity, dynamic cellular changes in adipose tissue result in phenotypic switching and adipose tissue dysfunction, including pathological expansion, WAT fibrosis, immune cell infiltration, endoplasmic reticulum stress, and ectopic lipid accumulation, ultimately leading to chronic low-grade inflammation and insulin resistance. Recently, many distinct subpopulations of adipose tissue have been identified, providing new insights into the potential mechanisms of adipose dysfunction in individuals with obesity. Therefore, targeting white adipose tissue as a therapeutic agent for treating obesity and obesity-related metabolic diseases is of great scientific interest. Here, we provide an overview of white adipose tissue remodeling in individuals with obesity including cellular changes and discuss the underlying regulatory mechanisms of white adipose tissue metabolic dysfunction. Currently, various studies have uncovered promising targets and strategies for obesity treatment. We also outline the potential therapeutic signaling pathways of targeting adipose tissue and summarize existing therapeutic strategies for antiobesity treatment including pharmacological approaches, lifestyle interventions, and novel therapies.

Spatial mapping of hepatic ER and mitochondria architecture reveals zonated remodeling in fasting and obesity

The hepatocytes within the liver present an immense capacity to adapt to changes in nutrient availability. Here, by using high resolution volume electron microscopy, we map how hepatic subcellular spatial organization is regulated during nutritional fluctuations and as a function of liver zonation. We identify that fasting leads to remodeling of endoplasmic reticulum (ER) architecture in hepatocytes, characterized by the induction of single rough ER sheet around the mitochondria, which becomes larger and flatter. These alterations are enriched in periportal and mid-lobular hepatocytes but not in pericentral hepatocytes. Gain- and loss-of-function in vivo models demonstrate that the Ribosome receptor binding protein1 (RRBP1) is required to enable fasting-induced ER sheet-mitochondria interactions and to regulate hepatic fatty acid oxidation. Endogenous RRBP1 is enriched around periportal and mid-lobular regions of the liver. In obesity, ER-mitochondria interactions are distinct and fasting fails to induce rough ER sheet-mitochondrion interactions. These findings illustrate the importance of a regulated molecular architecture for hepatocyte metabolic flexibility.

Specific and shared biological functions of PARP2 - is PARP2 really a lil' brother of PARP1?

PARP2, that belongs to the family of ADP-ribosyl transferase enzymes (ART), is a discovery of the millennium, as it was identified in 1999. Although PARP2 was described initially as a DNA repair factor, it is now evident that PARP2 partakes in the regulation or execution of multiple biological processes as inflammation, carcinogenesis and cancer progression, metabolism or oxidative stress-related diseases. Hereby, we review the involvement of PARP2 in these processes with the aim of understanding which processes are specific for PARP2, but not for other members of the ART family. A better understanding of the specific functions of PARP2 in all of these biological processes is crucial for the development of new PARP-centred selective therapies.

Unsaturated Fatty Acid Synthesis Is Associated with Worse Survival and Is Differentially Regulated by MYCN and Tumor Suppressor microRNAs in Neuroblastoma

MYCN amplification (MNA) and disruption of tumor suppressor microRNA (TSmiR) function are key drivers of poor outcomes in neuroblastoma (NB). While MYCN and TSmiRs regulate glucose metabolism, their role in de novo fatty acid synthesis (FAS) and unsaturated FAS (UFAS) remains poorly understood. Here, we show that FAS and UFAS (U/FAS) genes FASN, ELOVL6, SCD, FADS2, and FADS1 are upregulated in high-risk (HR) NB and that their expression is associated with lower overall survival. RNA-Seq analysis of human NB cell lines revealed parallel U/FAS gene expression patterns. Consistent with this, we found that NB-related TSmiRs were predicted to target these genes extensively. We further observed that both MYC and MYCN upregulated U/FAS pathway genes while suppressing TSmiR host gene expression, suggesting a possible U/FAS regulatory network between MYCN and TSmiRs in NB. NB cells are high in de novo synthesized omega 9 (ω9) unsaturated fatty acids and low in both ω6 and ω3, suggesting a means for NB to limit cell-autonomous immune stimulation and reactive oxygen species (ROS)-driven apoptosis from ω6 and ω3 unsaturated fatty acid derivatives, respectively. We propose a model in which MYCN and TSmiRs regulate U/FAS and play an important role in NB pathology, with implications for other MYC family-driven cancers.

Functional Plasmonic Microscope: Characterizing the Metabolic Activity of Single Cells via Sub-nm Membrane Fluctuations

Metabolic abnormalities are at the center of many diseases, and the capability to film and quantify the metabolic activities of a single cell is important for understanding the heterogeneities in these abnormalities. In this paper, a functional plasmonic microscope (FPM) is used to image and measure metabolic activities without fluorescent labels at a single-cell level. The FPM can accurately image and quantify the subnanometer membrane fluctuations with a spatial resolution of 0.5 μm in real time. These active cell membrane fluctuations are caused by metabolic activities across the cell membrane. A three-dimensional (3D) morphology of the bottom cell membrane was imaged and reconstructed with FPM to illustrate the capability of the microscope for cell membrane characterization. Then, the subnanometer cell membrane fluctuations of single cells were imaged and quantified with the FPM using HeLa cells. Cell metabolic heterogeneity is analyzed based on membrane fluctuations of each individual cell that is exposed to similar environmental conditions. In addition, we demonstrated that the FPM could be used to evaluate the therapeutic responses of metabolic inhibitors (glycolysis pathway inhibitor STF 31) on a single-cell level. The result showed that the metabolic activities significantly decrease over time, but the nature of this response varies, depicting cell heterogeneity. A low-concentration dose showed a reduced fluctuation frequency with consistent fluctuation amplitudes, while the high-concentration dose showcased a decreasing trend in both cases. These results have demonstrated the capabilities of the functional plasmonic microscope to measure and quantify metabolic activities for drug discovery.

Role of Hypoxia-Inducible Factor 1α in Adaptation to Hypoxia in the Pathogenesis of Novel Coronavirus Disease 2019

INTRODUCTION: A novel coronavirus (severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2)) emerged in December 2019 and rapidly spread over the world having provoked a pandemic of respiratory disease. This highly pathogenic virus can attack the lung tissue and derange gas exchange leading to acute respiratory distress syndrome and systemic hypoxia. Hypoxic conditions trigger activation of adaptation mechanisms including hypoxia-inducible factor-1á (HIF-1á) which is involved in the regulation of the key processes, e. g, proliferation and metabolism of cells and angiogenesis. Besides, the level of HIF-1á expression is associated with the intensity of the immune response of an organism including that of the innate immunity mediating inflammatory reaction. Therefore, understanding the peculiarities of the mechanisms underlying the pathogenesis of this disease is of great importance for effective therapy of coronavirus disease 2019 (COVID-19). AIM: Analysis of the current data on HIF-1á and its effect on the pathogenesis and progression of COVID-19. The analysis of the relevant domestic and international literature sources was performed in the following sections: HIF-1á as a key factor of adaptation to hypoxia, targets for HIF-1á in the aspect of the pathogenesis of COVID-19, disorders in HIF-1á-mediated adaptation to hypoxia as an element of the pathogenesis of hyperactivation of the immune cells. CONCLUSION: HIF-1á prevents penetration of SARS-CoV-2 virus into a cell and primarily acts as the main regulator of the proinflammatory activity at the inflammation site surrounded by hypoxia. In the conditions of the deranged metabolic flexibility, a high level of HIF-1á evokes an excessive inflammatory response of the immune cells. A high HIF-1á level in cells of the inflammation focus is associated with enhanced production of the factors of angiogenesis mediating vascular permeability and capillary leakage process. This is accompanied by tissue damage and organ failure. At the same time, HIF-1á can mediate the anti-inflammatory effect through activation of adenosine receptor-dependent pathway, which is considered as a probable protection of cells and organs against damage by hyperactive immune cells.

Respiratory Infection- and Asthma-prone, Low Vaccine Responder Children Demonstrate Distinct Mononuclear Cell DNA Methylation Pathways

Background

Infants with frequent viral and bacterial respiratory infections exhibit compromised immunity to routine immunisations. They are also more likely to develop chronic respiratory diseases in later childhood. This study investigated the feasibility of epigenetic profiling to reveal endotype-specific molecular pathways with potential for early identification and immuno-modulation. Peripharal immune cells from respiratory infection allergy/asthma prone (IAP) infants were retrospectively selected for genome-wide DNA methylation and single nucleotide polymorphism analysis. The IAP infants were enriched for the low vaccine responsiveness (LVR) phenotype (Fishers Exact p-value = 0.01).

Results

An endotype signature of 813 differentially methylated regions (DMRs) comprising 238 lead CpG associations (FDR < 0.05) emerged, implicating pathways related to asthma, mucin production, antigen presentation and inflammasome activation. Allelic variation explained only a minor portion of this signature. Stimulation of mononuclear cells with monophosphoryl lipid A (MPLA), a TLR agonist, partially reversing this signature at a subset of CpGs, suggesting the potential for epigenetic remodelling.

Conclusions

This proof-of-concept study establishes a foundation for precision endotyping of IAP children and highlights the potential for immune modulation strategies using adjuvants for furture investigation.

JAK/STAT mediated insulin resistance in muscles is essential for effective immune response

BACKGROUND

The metabolically demanding nature of immune response requires nutrients to be preferentially directed towards the immune system at the expense of peripheral tissues. We study the mechanisms by which this metabolic reprograming occurs using the parasitoid infection of Drosophila larvae. To overcome such an immune challenge hemocytes differentiate into lamellocytes, which encapsulate and melanize the parasitoid egg. Hemocytes acquire the energy for this process by expressing JAK/STAT ligands upd2 and upd3, which activates JAK/STAT signaling in muscles and redirects carbohydrates away from muscles in favor of immune cells.

METHODS

Immune response of Drosophila larvae was induced by parasitoid wasp infestation. Carbohydrate levels, larval locomotion and gene expression of key proteins were compared between control and infected animals. Efficacy of lamellocyte production and resistance to wasp infection was observed for RNAi and mutant animals.

RESULTS

Absence of upd/JAK/STAT signaling leads to an impaired immune response and increased mortality. We demonstrate how JAK/STAT signaling in muscles leads to suppression of insulin signaling through activation of ImpL2, the inhibitor of Drosophila insulin like peptides.

CONCLUSIONS

Our findings reveal cross-talk between immune cells and muscles mediates a metabolic shift, redirecting carbohydrates towards immune cells. We emphasize the crucial function of muscles during immune response and show the benefits of insulin resistance as an adaptive mechanism that is necessary for survival.

Three-week sprint interval training (SIT) reduces cell-free DNA and low-frequency fatigue but does not induce VO2max improvement in older men

PURPOSE

This study aimed to investigate the impact of sprint interval training (SIT) on both the acute and 3-week modulations of cell-free DNA (cfDNA), as well as its association with neuromuscular fatigue and physical performance in healthy young and old men.

METHODS

Ten young (20-25 year old) and nine elderly (63-72 year old) healthy men performed nine SIT sessions consisting of 4-to-6-all-out cycling repetitions of 30 s interspaced with 4-min rest intervals. We compared the maximal voluntary contractions torque, central activation ratio, low-frequency fatigue (LFF), and cfDNA concentrations between the groups before, immediately after, 1 h after, and 24 h after the first and ninth SIT sessions.

RESULTS

The plasma cfDNA levels were increased post-exercise (from 1.4 ± 0.258 to 1.91 ± 0.278 ng/ml (P < 0.01) on a log10 scale), without significant differences between the groups. However, older individuals showed a slight decrease in the baseline cfDNA values, from 1.39 ± 0.176 to 1.29 ± 0.085 ng/ml on a log10 scale, after 3 weeks (P = 0.043). Importantly, the elevation of the post-exercise cfDNA values was correlated with an increase in LFF in both groups. Three weeks of SIT induced an improvement in the recovery of LFF (main session effect, P = 0.0029); however, only the young group showed an increase in aerobic capacity (VO2max) (from 40.8 ± 6.74 to 43.0 ± 5.80 ml/kg/min, P = 0.0039).

CONCLUSION

Three weeks of SIT diminished the baseline cfDNA values in the old group, together with an improvement in the recovery of LFF. However, VO2max was increased only in the young group.

Divergence in aerobic capacity and energy expenditure influence metabolic tissue mitochondrial protein synthesis rates in aged rats

Age-associated declines in aerobic capacity promote the development of various metabolic diseases. In rats selectively bred for high/low intrinsic aerobic capacity, greater aerobic capacity reduces susceptibility to metabolic disease while increasing longevity. However, little remains known how intrinsic aerobic capacity protects against metabolic disease, particularly with aging. Here, we tested the effects of aging and intrinsic aerobic capacity on systemic energy expenditure, metabolic flexibility and mitochondrial protein synthesis rates using 24-month-old low-capacity (LCR) or high-capacity runner (HCR) rats. Rats were fed low-fat diet (LFD) or high-fat diet (HFD) for eight weeks, with energy expenditure (EE) and metabolic flexibility assessed utilizing indirect calorimetry during a 48 h fast/re-feeding metabolic challenge. Deuterium oxide (D2O) labeling was used to assess mitochondrial protein fraction synthesis rates (FSR) over a 7-day period. HCR rats possessed greater EE during the metabolic challenge. Interestingly, HFD induced changes in respiratory exchange ratio (RER) in male and female rats, while HCR female rat RER was largely unaffected by diet. In addition, analysis of protein FSR in skeletal muscle, brain, and liver mitochondria showed tissue-specific adaptations between HCR and LCR rats. While brain and liver protein FSR were altered by aerobic capacity and diet, these effects were less apparent in skeletal muscle. Overall, we provide evidence that greater aerobic capacity promotes elevated EE in an aged state, while also regulating metabolic flexibility in a sex-dependent manner. Modulation of mitochondrial protein FSR by aerobic capacity is tissue-specific with aging, likely due to differential energetic requirements by each tissue.

The Association of Macronutrient Consumption and BMI to Exhaled Carbon Dioxide in Lumen Users: Retrospective Real-World Study

BACKGROUND

Metabolic flexibility is the ability of the body to rapidly switch between fuel sources based on their accessibility and metabolic requirements. High metabolic flexibility is associated with improved health outcomes and a reduced risk of several metabolic disorders. Metabolic flexibility can be improved through lifestyle changes, such as increasing physical activity and eating a balanced macronutrient diet. Lumen is a small handheld device that measures metabolic fuel usage through exhaled carbon dioxide (CO2), which allows individuals to monitor their metabolic flexibility and make lifestyle changes to enhance it.

OBJECTIVE

This retrospective study aims to examine the postprandial CO2 response to meals logged by Lumen users and its relationship with macronutrient intake and BMI.

METHODS

We analyzed deidentified data from 2607 Lumen users who logged their meals and measured their exhaled CO2 before and after those meals between May 1, 2023, and October 18, 2023. A linear mixed model was fitted to test the association between macronutrient consumption, BMI, age, and gender to the postprandial CO2 response, followed by a 2-way ANOVA.

RESULTS

The model demonstrated significant associations (P<.001) between CO2 response after meals and both BMI and carbohydrate intake (BMI: β=-0.112, 95% CI -0.156 to -0.069; carbohydrates: β=0.046, 95% CI 0.034-0.058). In addition, a 2-way ANOVA revealed that higher carbohydrate intake resulted in a higher CO2 response compared to low carbohydrate intake (F2,2569=24.23; P<.001), and users with high BMI showed modest responses to meals compared with low BMI (F2,2569=5.88; P=.003).

CONCLUSIONS

In this study, we show that Lumen's CO2 response is influenced both by macronutrient consumption and BMI. The results of this study highlight a distinct pattern of reduced metabolic flexibility in users with obesity, indicating the value of Lumen for assessing postprandial metabolic flexibility.

Metabolomic Profiles and Pathways in Osteoarthritic Human Cartilage: A Comparative Analysis with Healthy Cartilage

Osteoarthritis (OA) is a chronic joint disease with heterogenous metabolic pathology. To gain insight into OA-related metabolism, metabolite extracts from healthy (n = 11) and end-stage osteoarthritic cartilage (n = 35) were analyzed using liquid chromatography-mass spectrometry metabolomic profiling. Specific metabolites and metabolic pathways, including lipid and amino acid pathways, were differentially regulated in osteoarthritis-derived and healthy cartilage. The detected alterations in amino acids and lipids highlighted key differences in bioenergetic resources, matrix homeostasis, and mitochondrial alterations in OA-derived cartilage compared to healthy cartilage. Moreover, the metabolomic profiles of osteoarthritic cartilage separated into four distinct endotypes, highlighting the heterogenous nature of OA metabolism and the diverse landscape within the joint in patients. The results of this study demonstrate that human cartilage has distinct metabolomic profiles in healthy and end-stage OA patients. By taking a comprehensive approach to assess metabolic differences between healthy and osteoarthritic cartilage and within osteoarthritic cartilage alone, several metabolic pathways with distinct regulation patterns were detected. Additional investigation may lead to the identification of metabolites that may serve as valuable indicators of disease status or potential therapeutic targets.

Fasting as a precursor to high-fat diet enhances mitochondrial resilience in Drosophila melanogaster

Changes in diet type and nutrient availability can impose significant environmental stress on organisms, potentially compromising physiological functions and reproductive success. In nature, dramatic fluctuations in dietary resources are often observed and adjustments to restore cellular homeostasis are crucial to survive this type of stress. In this study, we exposed male Drosophila melanogaster to two modulated dietary treatments: one without a fasting period before exposure to a high-fat diet and the other with a 24-h fasting period. We then investigated mitochondrial metabolism and molecular responses to these treatments. Exposure to a high-fat diet without a preceding fasting period resulted in disrupted mitochondrial respiration, notably at the level of complex I. On the other hand, a short fasting period before the high-fat diet maintained mitochondrial respiration. Generally, transcript abundance of genes associated with mitophagy, heat-shock proteins, mitochondrial biogenesis, and nutrient sensing pathways increased either slightly or significantly following a fasting period and remained stable when flies were subsequently put on a high-fat diet, whereas a drastic decrease of almost all transcript abundances was observed for all these pathways when flies were exposed directly to a high-fat diet. Moreover, mitochondrial enzymatic activities showed less variation after the fasting period than the treatment without a fasting period. Overall, our study sheds light on the mechanistic protective effects of fasting prior to a high-fat diet and highlights the metabolic flexibility of Drosophila mitochondria in response to abrupt dietary changes and have implication for adaptation of species to their changing environment.

Chronic exercise improves hepatic acylcarnitine handling

Exercise mediates tissue metabolic function through direct and indirect adaptations to acylcarnitine (AC) metabolism, but the exact mechanisms are unclear. We found that circulating medium-chain acylcarnitines (AC) (C12-C16) are lower in active/endurance trained human subjects compared to sedentary controls, and this is correlated with elevated cardiorespiratory fitness and reduced adiposity. In mice, exercise reduced serum AC and increased liver AC, and this was accompanied by a marked increase in expression of genes involved in hepatic AC metabolism and mitochondrial β-oxidation. Primary hepatocytes from high-fat fed, exercise trained mice had increased basal respiration compared to hepatocytes from high-fat fed sedentary mice, which may be attributed to increased Ca2+ cycling and lipid uptake into mitochondria. The addition of specific medium- and long-chain AC to sedentary hepatocytes increased mitochondrial respiration, mirroring the exercise phenotype. These data indicate that AC redistribution is an exercise-induced mechanism to improve hepatic function and metabolism.

Association between the Static and Dynamic Lung Function and CT-Derived Thoracic Skeletal Muscle Measurements-A Retrospective Analysis of a 12-Month Observational Follow-Up Pilot Study

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) with low skeletal muscle mass and severe airway obstruction have higher mortality risks. However, the relationship between dynamic/static lung function (LF) and thoracic skeletal muscle measurements (SMM) remains unclear. This study explored patient characteristics (weight, BMI, exacerbations, dynamic/static LF, sex differences in LF and SMM, and the link between LF and SMM changes.

METHODS

A retrospective analysis of a 12-month prospective follow-up study patients with stable COPD undergoing standardized treatment, covering mild to severe stages, was conducted. The baseline and follow-up assessments included computed tomography and body plethysmography.

RESULTS

This study included 35 patients (17 females and 18 males). This study revealed that females had more stable LF but tended to have greater declines in SMM areas and indices than males (-5.4% vs. -1.9%, respectively), despite the fact that females were younger and had higher LF and less exacerbation than males. A multivariate linear regression showed a negative association between the inspiratory capacity/total lung capacity ratio (IC/TLC) and muscle fat area.

CONCLUSIONS

The findings suggest distinct LF and BC progression patterns between male and female patients with COPD. A low IC/TLC ratio may predict increased muscle fat. Further studies are necessary to understand these relationships better.

Volume-based subglottic secretion drainage: a randomized controlled trial

Background

This study proposed to explore individual management mode for patients with subglottic secretion drainage.

Methods

Randomly chosen within the hospital ICU 68 patients from 7 April to 15 June 2023, all the patients randomly assigned to the control group or observation group, and control group adopts the model of intermittent drainage management, observation group based on the volume of subglottic secretion in patients with individualized management, and then analysis the two groups of patients clinical trial results.

Results

The clinical trial results showed that there were statistically significant differences (P<0.05) between the control group and the observation group in the incidence of tube blockage events (11 vs. 2), average diurnal pumping frequency (9 vs. 7, 5 vs. 4) between the two groups and the patient satisfaction scores (6 vs. 7), In the partial mucosa injure (22 vs 19) and VAP (5 vs. 1) there were no statistically significant difference (P>0.05). Although there was no statistically significant difference (P>0.05) in the average aspiration volume (12.68±3.41 vs. 12.19±2.68, 8 vs. 8) between the two groups, but the management mode of the observation group indicated that based on patient secretion volume was more consistent with the characteristics of the body's diurnal metabolic differences, because there was a big difference between the average total amount of daytime and nighttime suction between the two groups.

Conclusion

Individualized management based on the volume of subglottic secretions produced by patients can further optimize the airway management of patients and reduce the risk of adverse events of subglottic secretions aspiration.

Machine learning identifies fatigue as a key symptom of fibromyalgia reflected in tyrosine, purine, pyrimidine, and glutaminergic metabolism

Fibromyalgia patients vary in clinical phenotype and treatment can be challenging. The pathophysiology of fibromyalgia is incompletely understood but appears to involve metabolic changes at rest or in response to stress. We enrolled 54 fibromyalgia patients and 31 healthy controls to this prospective study. Symptoms were assessed using the Fibromyalgia Impact Questionnaire (FIQ) and blood samples were collected for metabolomics analysis at baseline and after an oral glucose tolerance test and a cardiopulmonary exercise test. We identified key symptoms of fibromyalgia and related them to changes in metabolic pathways with supervised and unsupervised machine learning methods. Algorithms trained with the FIQ information assigned the fibromyalgia diagnosis in new data with balanced accuracy of 88% while fatigue alone already provided the diagnosis with 86% accuracy. Supervised analyses reduced the metabolomic information from 77 to 13 key markers. With these metabolites, fibromyalgia could be identified in new cases with 79% accuracy. In addition, 5-hydroxyindole-3-acetic acid and glutamine levels correlated with the severity of fatigue. Patients differed from controls at baseline in tyrosine and purine pathways, and in the pyrimidine pathway after the stress challenges. Several key markers are involved in glutaminergic neurotransmission. This data-driven analysis highlights fatigue as a key symptom of fibromyalgia. Fibromyalgia is associated with metabolic changes which also reflect the degree of fatigue. Responses to metabolic and physical stresses result in a metabolic pattern that allows discrimination of fibromyalgia patients from controls and narrows the focus on key pathophysiological processes in fibromyalgia as treatment targets.

The role of adipogenic capacity and dysfunctional subcutaneous adipose tissue in the inheritance of type 2 diabetes mellitus: cross-sectional study

OBJECTIVE

This study tested the hypothesis that limited subcutaneous adipose tissue (SAT) expansion represents a primary predisposition to the development of type 2 diabetes mellitus (T2DM), independent of obesity, and identified novel markers of SAT dysfunction in the inheritance of T2DM.

METHODS

First-degree relatives (FDR) of T2DM patients (n = 19) and control individuals (n = 19) without obesity (fat mass < 25%) were cross-sectionally compared. Body composition (bioimpedance, computed tomography) and insulin sensitivity (IS; oral glucose tolerance test, clamp) were measured. SAT obtained by needle biopsy was used to analyze adipocyte size, lipidome, mRNA expression, and inflammatory markers. Primary cultures of adipose precursors were analyzed for adipogenic capacity and metabolism.

RESULTS

Compared with control individuals, FDR individuals had lower IS and a higher amount of visceral fat. However, SAT-derived adipose precursors did not differ in their ability to proliferate and differentiate or in metabolic parameters (lipolysis, mitochondrial oxidation). In SAT of FDR individuals, lipidomic and mRNA expression analysis revealed accumulation of triglycerides containing polyunsaturated fatty acids and increased mRNA expression of lysyl oxidase (LOX). These parameters correlated with IS, visceral fat accumulation, and mRNA expression of inflammatory and cellular stress genes.

CONCLUSIONS

The intrinsic adipogenic potential of SAT is not affected by a family history of T2DM. However, alterations in LOX mRNA and polyunsaturated fatty acids in triacylglycerols are likely related to the risk of developing T2DM independent of obesity.

Ketogenic nutritional therapy (KeNuT)-a multi-step dietary model with meal replacements for the management of obesity and its related metabolic disorders: a consensus statement from the working group of the Club of the Italian Society of Endocrinology (SIE)-diet therapies in endocrinology and metabolism

PURPOSE

The ketogenic nutritional therapy (KeNuT) is an effective dietary treatment for patients with obesity and obesity-related comorbidities, including type 2 diabetes, dyslipidaemia, hypertension, coronary artery disease, and some type of cancers. However, to date an official document on the correct prescription of the ketogenic diet, validated by authoritative societies in nutrition or endocrine sciences, is missing. It is important to emphasize that the ketogenic nutritional therapy requires proper medical supervision for patient selection, due to the complex biochemical implications of ketosis and the need for a strict therapeutic compliance, and an experienced nutritionist for proper personalization of the whole nutritional protocol.

METHODS

This practical guide provides an update of main clinical indications and contraindications of ketogenic nutritional therapy with meal replacements and its mechanisms of action. In addition, the various phases of the protocol involving meal replacements, its monitoring, clinical management and potential side effects, are also discussed.

CONCLUSION

This practical guide will help the healthcare provider to acquire the necessary skills to provide a comprehensive care of patients with overweight, obesity and obesity-related diseases, using a multistep ketogenic dietary treatment, recognized by the Club of the Italian Society of Endocrinology (SIE)-Diet Therapies in Endocrinology and Metabolism.

Impact of fasting on the AMPK and PGC-1α axis in rodent and human skeletal muscle: A systematic review

Based primarily on evidence from rodent models fasting is currently believed to improve metabolic health via activation of the AMPK-PGC-1α axis in skeletal muscle. However, it is unclear whether the skeletal muscle AMPK-PGC-1α axis is activated by fasting in humans. The current systematic review examined the fasting response in skeletal muscle from 34 selected studies (7 human, 21 mouse, and 6 rat). From these studies, we gathered 38 unique data points related to AMPK and 47 related to PGC-1α. In human studies, fasting mediated activation of the AMPK-PGC-1α axis is largely absent. Although evidence does support fasting-induced activation of the AMPK-PGC-1α axis in rodent skeletal muscle, the evidence is less robust than anticipated. Our findings question the ability of fasting to activate the AMPK-PGC-1α axis in human skeletal muscle and suggest that the metabolic benefits of fasting in humans are associated with caloric restriction rather than the induction of mitochondrial biogenesis. Registration: https://doi.org/10.17605/OSF.IO/KWNQY.