Hypercaloric low-carbohydrate high-fat diet protects against the development of nonalcoholic fatty liver disease in obese mice in contrast to isocaloric Western diet.

Objective: Obesity and metabolic complications, such as type 2 diabetes and nonalcoholic fatty liver disease (NAFLD), are one of the greatest public health challenges of the 21st century. The major role of high sugar and carbohydrate consumption rather than caloric intake in obesity and NAFLD pathophysiology remains a subject of debate. A low-carbohydrate but high-fat diet (LCHFD) has shown promising results in obesity management, but its effects in preventing NAFLD need to be detailed. This study aims to compare the effects of a LCHFD with a high-fat high-sugar obesogenic Western diet (WD) on the progression of obesity, type 2 diabetes, and nonalcoholic fatty liver disease. Methods: Male C57BL/6J mice were initially fed a WD for 10 weeks. Subsequently, they were either switched to a LCHFD or maintained on the WD for an additional 6 weeks. Hepatic effects of the diet were explored by histological staining and RT-qPCR. Results: After the initial 10 weeks WD feeding, LCHF diet demonstrated effectiveness in halting weight gain, maintaining a normal glucose tolerance and insulin levels, in comparison to the WD-fed mice, which developed obesity, glucose intolerance, increased insulin levels and induced NAFLD. In the liver, LCHFD mitigated the accumulation of hepatic triglycerides and the increase in Fasn relative gene expression compared to the WD mice. Beneficial effects of the LCHFD occurred despite a similar calorie intake compared to the WD mice. Conclusion: Our results emphasize the negative impact of a high sugar/carbohydrate and lipid association for obesity progression and NAFLD development. LCHFD has shown beneficial effects for NAFLD management, notably improving weight management, and maintaining a normal glucose tolerance and liver health.

Changes in Macronutrients during Dieting Lead to Weight Cycling and Metabolic Complications in Mouse Model.

Weight cycling is a major challenge in obesity management. Caloric restriction is known to promote this phenomenon, but the impact of macronutrient changes during dieting remains unclear. This study aimed to determine the role of macronutrient changes in weight maintenance without caloric restriction by alternating between two hypercaloric diets: a high-carbohydrate, high-fat Western diet (WD) and a low-carbohydrate, high-fat diet (LCHDF). Obesity was induced in 8-week-old C57BL/6 male mice by 10 weeks of WD feeding. Then, the mice were subjected to 12 weeks of LCHFD interspersed with WD (I-WD), 3 periods of 2-week LCHFD followed by 2 periods of 3-week WD, or 12 weeks of continuous WD (C-WD). C-WD and I-WD mice were compared to standard diet (SD) mice. In the I-WD group, each LCHFD period decreased weight gain, but mice regained weight after WD resumption. I-WD mice exhibited obesity, dyslipidemia, and glucose intolerance, similarly to the C-WD mice. I-WD mice also developed nonalcoholic steatohepatitis, associated with an increase in type-III collagen gene expression and a decrease in FGF21 protein levels, in comparison with SD. I-WD mice developed weight cycling despite maintaining a high caloric consumption, suggesting that changes in macronutrients during dieting are also a trigger of weight regain.

[Beneficial effects of ketogenic diet for Alzheimer's disease management]. / Intérêt du régime cétogène dans la prise en charge de la maladie d'Alzheimer.

Alzheimer's disease (AD) is a neurodegenerative disease that affects almost 1 million people in France and 55 million in the world. This pathology is a global health preoccupation because of the lack of efficient curative treatment and the increase of its prevalence. During the last decade, the comprehension of pathophysiological mechanisms involved in AD have been improved. Amyloid plaques and neurofibrillary tangles accumulation are characteristic of Alzheimer's brain patients, accompanied by increased brain inflammation and oxidative stress, impaired cerebral metabolism of glucose and mitochondrial function. Treatment of AD includes different approaches, as pharmacology, psychology support, physiotherapy, and speech therapy. However, these interventions do not have a curative effect, but only compensatory on the disease. Ketogenic diet (KD), a low-carbohydrates and high-fat diet, associated with a medium-chain triglycerides intake (MCTs) might induce benefices for Alzheimer disease patients. Carbohydrate restriction and MCTs promotes the production of ketone bodies from fatty acid degradation. These metabolites replacing glucose, serve the brain as energetic substrates, and induce neuroprotective effects. Such a nutritional support might slow down the disease progression and improve cognitive abilities of patients. This review aims to examine the neuroprotective mechanisms of KD in AD progression and describes the advantages and limitations of KD as a therapeutic strategy.

Title: Intérêt du régime cétogène dans la prise en charge de la maladie d'Alzheimer. Abstract: La maladie d'Alzheimer (MA), pathologie neurodégénérative en expansion, devient une préoccupation importante de santé publique, en raison d'une absence de traitement curatif efficace. Les mécanismes mis en œuvre dans la physiopathologie de la MA sont de mieux en mieux connus, et incluent l'accumulation de plaques amyloïdes et de dégénérescences neurofibrillaires. L'augmentation de l'inflammation et du stress oxydant et l'altération du métabolisme cérébral du glucose aggravent la pathologie en réduisant l'activité neuronale en perturbant la fonction mitochondriale. À l'heure actuelle, le traitement de cette pathologie regroupe différentes approches bien que ces interventions n'aient pas un effet curatif, mais uniquement compensatoire. L'alimentation cétogène, pauvre en glucides et enrichie en lipides, couplée à une prise de triglycérides à chaîne moyenne (MCT), favorise la production de corps cétoniques, substrats énergétiques qui pourraient présenter des effets neuroprotecteurs bénéfiques pour les personnes atteintes de la MA. Une telle prise en charge nutritionnelle pourrait limiter la progression de la maladie et améliorer les capacités cognitives des patients. Cette revue vise à examiner le rôle éventuel et les mécanismes neuroprotecteurs de l'alimentation cétogène dans la progression de la MA, et décrit les avantages et les limites de son utilisation comme stratégie thérapeutique.

Androgen receptor coordinates muscle metabolic and contractile functions.

BACKGROUND: Androgens are anabolic steroid hormones that exert their function by binding to the androgen receptor (AR). We have previously established that AR deficiency in limb muscles impairs sarcomere myofibrillar organization and decreases muscle strength in male mice. However, despite numerous studies performed in men and rodents, the signalling pathways controlled by androgens via their receptor in skeletal muscles remain poorly understood. METHODS: Male ARskm-/y (n = 7-12) and female ARskm-/- mice (n = 9), in which AR is selectively ablated in myofibres of musculoskeletal tissue, and male AR(i)skm-/y , in which AR is selectively ablated in post-mitotic skeletal muscle myofibres (n = 6), were generated. Longitudinal monitoring of body weight, blood glucose, insulin, lipids and lipoproteins was performed, alongside metabolomic analyses. Glucose metabolism was evaluated in C2C12 cells treated with 5α-dihydrotestosterone (DHT) and the anti-androgen flutamide (n = 6). Histological analyses on macroscopic and ultrastructural levels of longitudinal and transversal muscle sections were conducted. The transcriptome of gastrocnemius muscles from control and ARskm-/y mice was analysed at the age of 9 weeks (P < 0.05, 2138 differentially expressed genes) and validated by RT-qPCR analysis. The AR (4691 peaks with false discovery rate [FDR] < 0.1) and H3K4me2 (47 225 peaks with FDR < 0.05) cistromes in limb muscles were determined in 11-week-old wild-type mice. RESULTS: We show that disrupting the androgen/AR axis impairs in vivo glycolytic activity and fastens the development of type 2 diabetes in male, but not in female mice. In agreement, treatment with DHT increases glycolysis in C2C12 myotubes by 30%, whereas flutamide has an opposite effect. Fatty acids are less efficiently metabolized in skeletal muscles of ARskm-/y mice and accumulate in cytoplasm, despite increased transcript levels of genes encoding key enzymes of beta-oxidation and mitochondrial content. Impaired glucose and fatty acid metabolism in AR-deficient muscle fibres is associated with 30% increased lysine and branched-chain amino acid catabolism, decreased polyamine biosynthesis and disrupted glutamate transamination. This metabolic switch generates ammonia (2-fold increase) and oxidative stress (30% increased H2 O2 levels), which impacts mitochondrial functions and causes necrosis in <1% fibres. We unravel that AR directly activates the transcription of genes involved in glycolysis, oxidative metabolism and muscle contraction. CONCLUSIONS: Our study provides important insights into diseases caused by impaired AR function in musculoskeletal system and delivers a deeper understanding of skeletal muscle pathophysiological dynamics that is instrumental to develop effective treatment for muscle disorders.

Development of skeletal muscle atrophy and intermuscular adipose tissue in patients with early breast cancer treated with chemotherapy.

Chemotherapy is a common therapy to treat patients with breast cancer but also leads to skeletal muscle deconditioning. Skeletal muscle deconditioning is multifactorial and intermuscular adipose tissue (IMAT) accumulation is closely linked to muscle dysfunction. To date, there is no clinical study available investigating IMAT development through a longitudinal protocol and the underlying mechanisms remain unknown. Our study was dedicated to investigating IMAT content in patients with early breast cancer who were treated with chemotherapy and exploring the subsequent cellular mechanisms involved in its development. We included 13 women undergoing chemotherapy. Muscle biopsies and ultrasonography assessment were performed before and after chemotherapy completion. Histological and Western blotting analyses were conducted. We found a substantial increase in protein levels of three mature adipocyte markers (perilipin, +901%; adiponectin, +135%; FABP4, +321%; P < 0.05). These results were supported by an increase in oil red O-positive staining (+358%; P < 0.05). A substantial increase in PDGFRα protein levels was observed (+476%; P < 0.05) highlighting an increase in fibro-adipogenic progenitors (FAPs) content. The cross-sectional area of the vastus lateralis muscle fibers substantially decreased (-21%; P < 0.01), and muscle architecture was altered, as shown by a decrease in fascicle length (-15%; P < 0.05) and a decreasing trend in muscle thickness (-8%; P = 0.08). We demonstrated both IMAT development and muscle atrophy in patients with breast cancer who were treated with chemotherapy. FAPs, critical stem cells inducing both IMAT development and skeletal muscle atrophy, also increased, suggesting that FAPs likely play a critical role in the skeletal muscle deconditioning observed in patients with breast cancer who were treated with chemotherapy.

Octanoic Acid-Enrichment Diet Improves Endurance Capacity and Reprograms Mitochondrial Biogenesis in Skeletal Muscle of Mice.

Background: Medium Chain Fatty Acids (MCFAs) are a dietary supplement that exhibit interesting properties, due to their smaller molecular size. The acute consumption of MCFAs is expected to enhance exercise performance. However, the short-term effects of MCFAs on endurance performance remains poorly understood. The aim of our study is to evaluate the octanoic acid (C8)-rich diet effect on endurance capacity, and to explore their molecular and cellular effects. Methods: C57BL/6J mice were fed with a chow diet (Control group) or an octanoic acid-rich diet (C8 diet) for 6 weeks. Spontaneous activity, submaximal and maximal exercise tests were carried out to characterize the exercise capacities of the mice. Beta-oxidation and mitochondrial biogenesis pathways were explored in skeletal muscle by RT-qPCR, Western Blot (Quadriceps) and histochemical staining (Gastrocnemius). Results: Mice fed with a C8-rich diet presented a higher spontaneous activity (p < 0.05) and endurance capacities (p < 0.05) than the control, but no effect on maximal effort was observed. They also presented changes in the skeletal muscle metabolic phenotype, with a higher number of the oxidative fibers, rich in mitochondria. At the molecular level, the C8-diet induced an AMPK activation (p < 0.05), associated with a significant increase in PGC1a and CS gene expression and protein levels. Conclusion: Our study provided evidence that C8-enrichment as a food supplementation improves endurance capacities and activates mitochondrial biogenesis pathways leading to higher skeletal muscle oxidative capacities.

[Obesity, inflammation and COVID-19: preventive interest of ketogenic diet?] / Obésité, inflammation et COVID-19 : intérêt préventif de l'alimentation cétogène ?

Obesity is considered a pandemic responsible for millions of deaths worldwide for many years. At the end of 2019, the Coronavirus disease 2019 (COVID-19) appeared, causing the death of more than a million people in less than a year. Numerous studies suggest that obesity could be defined as key to the onset of severe forms of this emerging disease. Indeed, SARS-CoV2 infects the host by binding to ACE2 receptors present on the surface of the cells and causes excessive secretion of pro-inflammatory cytokines including IL-1, IL-6 and TNF-α, which lead to developing acute respiratory distress syndrome (ARDS). It therefore seems essential to make up effective preventive strategies to protect this part of the population from the risk of developing a severe form of COVID-19. The ketogenic diet, which is low in sugars and high in fat, has interesting properties, both in the fight against obesity but also against severe infections. This article focuses on the latest scientific advances that make it possible to consider the ketogenic diet as a preventive strategy that simultaneously reduces the development of obesity while strengthening the immune system, two key actions in the fight against SARS-CoV2 infections and severe forms of COVID-19.

TITLE: Obésité, inflammation et COVID-19 : intérêt préventif de l'alimentation cétogène ? ABSTRACT: L'obésité est considérée comme une pandémie responsable de plusieurs millions de morts dans le monde depuis de nombreuses années. Fin 2019 est apparue la maladie à Coronavirus 2019 (COVID-19) qui a provoqué la mort de plus d'un million de personnes en moins d'un an. De nombreuses études suggèrent que l'obésité pourrait être un paramètre clé dans l'apparition des formes graves de cette maladie émergente. En effet, le SARS-CoV2 infecte l'hôte en se fixant aux récepteurs ACE2 présents à la surface des cellules et entraîne une sécrétion excessive de cytokines pro-inflammatoires notamment l'IL-1, l'IL-6 et le TNF-α qui conduisent au développement d'un syndrome de détresse respiratoire aigu (SDRA). Il paraît essentiel d'élaborer des stratégies préventives efficaces pour protéger cette partie de la population du risque de développer une forme grave de COVID-19. L'alimentation cétogène, pauvre en sucres et riche en lipides, présente d'intéressantes propriétés, à la fois pour la lutte contre l'obésité mais également contre les infections sévères. Cet article fait le point sur les dernières avancées scientifiques qui permettent d'envisager l'alimentation cétogène comme une stratégie préventive visant à diminuer le développement de l'obésité et à renforcer le système immunitaire, deux actions clés dans la lutte contre l'infection au SARS-CoV2 et le développement de formes graves de COVID-19.

Beneficial Effects of Early Time-Restricted Feeding on Metabolic Diseases: Importance of Aligning Food Habits with the Circadian Clock.

The importance of metabolic health is a major societal concern due to the increasing prevalence of metabolic diseases such as obesity, diabetes, and various cardiovascular diseases. The circadian clock is clearly implicated in the development of these metabolic diseases. Indeed, it regulates physiological processes by hormone modulation, thus helping the body to perform them at the ideal time of day. Since the industrial revolution, the actions and rhythms of everyday life have been modified and are characterized by changes in sleep pattern, work schedules, and eating habits. These modifications have in turn lead to night shift, social jetlag, late-night eating, and meal skipping, a group of customs that causes circadian rhythm disruption and leads to an increase in metabolic risks. Intermittent fasting, especially the time-restricted eating, proposes a solution: restraining the feeding window from 6 to 10 h per day to match it with the circadian clock. This approach seems to improve metabolic health markers and could be a therapeutic solution to fight against metabolic diseases. This review summarizes the importance of matching life habits with circadian rhythms for metabolic health and assesses the advantages and limits of the application of time-restricted fasting with the objective of treating and preventing metabolic diseases.

[Ketogenic diet: a new nutritional strategy for cancer therapy?] / Le régime cétogène : une stratégie alimentaire efficace en complément des traitements contre le cancer ?

Cancer is a disease that can appear in several tissues and that kills more than 150 000 people in France every year. Cancer cells have mutations in their genome that lead to changes in their metabolism, compared to healthy cells. They use mostly glycolysis as their energy source, but not fatty acid oxidation. Currently, treatments used against cancer are nonspecific and have many side effects. Thus it appears increasingly important to find new strategies against cancer cells progression while protecting surrounding healthy cells and decreasing side effects. Ketogenic diet, which is a low-sugar high-fat diet, could be an interesting candidate as it alters the energy machinery of the cell and keeps away its primary energy source (glucose). This diet is largely used to treat refractory epilepsy and begins to be studied in oncology as well. This article describes the scientific evidence of the beneficial effects of the ketogenic diet and aims at showing how this complementary treatment could be useful against several cancers.

TITLE: Le régime cétogène : une stratégie alimentaire efficace en complément des traitements contre le cancer ? ABSTRACT: Le cancer est une pathologie qui touche tout type de tissu et qui tue chaque année en France plus de 150 000 personnes. Les cellules cancéreuses présentent des modifications dans leur métabolisme par rapport aux cellules saines, puisqu'elles tirent leur énergie très majoritairement de la glycolyse anaérobie et non de la phosphorylation oxydative mitochondriale : on parle de l'effet Warburg. À l'heure actuelle, les traitements les plus utilisés pour soigner le cancer en routine sont des traitements dits non spécifiques qui présentent de nombreux effets secondaires, altérant la vie des patients. Il semble de plus en plus crucial de trouver de nouvelles stratégies pour lutter contre la progression des cellules cancéreuses. Le régime cétogène, pauvre en sucres et riche en lipides, est un candidat intéressant, puisqu'il affaiblit la machinerie énergétique de la cellule cancéreuse. Ce régime est déjà utilisé dans le cadre de la prise en charge de l'épilepsie réfractaire aux traitements classiques, et commence à être étudié en cancérologie également. Cet article, qui fait le point sur les preuves scientifiques des effets bénéfiques du régime cétogène, souligne son intérêt thérapeutique potentiel comme traitement complémentaire pour lutter contre certains cancers.