Diurnal transcriptome landscape of a multi-tissue response to time-restricted feeding in mammals

The role of the multiplicity of circadian clocks in mammalian systems

Circadian clocks regulate rhythmic biological processes in nearly every tissue, aligning physiology and behavior with the 24-h light-dark cycle. While the central circadian clock in the suprachiasmatic nucleus (SCN) has been extensively studied, emerging evidence indicates that virtually every cell in the body possesses its own locally autonomous circadian clock. This raises a fundamental question: why do multicellular organisms utilize multiple circadian clocks instead of a single master clock broadcasting time cues? Here, we examine how distributed local clocks differ from phase-resettable cycles and ensure robust temporal scheduling of physiological processes. We discuss how internal entrainment among local clocks governs self-sustained, yet flexible, circadian organization of tissue-specific responses to environmental changes. We also examine how the organization of clocks contributes to seasonal homeostasis, and the implications for disease when coordination among these clocks is disrupted.

Metabolic dysfunction-associated steatotic liver disease (MASLD) in children with obesity: An Obesity Medicine Association (OMA) and expert joint perspective 2025

Introduction

This Obesity Medicine Association (OMA) Expert Joint Perspective examines steatotic liver disease (SLD), which is composed of metabolic dysfunction-associated steatotic liver disease (MASLD), and metabolic dysfunction-associated steatohepatitis (MASH) in children with obesity. The prevalence of obesity is increasing, rates have tripled since 1963 from 5 % to now 19 % of US children affected in 2018. MASLD, is the most common liver disease seen in children, can be a precursor to the development of Type 2 Diabetes (T2DM) and is the primary reason for liver transplant listing in young adults. We must be vigilant in prevention and treatment of MASLD in childhood to prevent further progression.

Methods

This joint clinical perspective is based upon scientific evidence, peer and clinical expertise. The medical literature was reviewed via PubMed search and appropriate articles were included in this review. This work was formulated from the collaboration of eight hepatologists/gastroenterologists with MASLD expertise and two physicians from the OMA.

Results

The authors who are experts in the field, determined sentinel questions often asked by clinicians regarding MASLD in children with obesity. They created a consensus and clinical guideline for clinicians on the screening, diagnosis, and treatment of MASLD associated with obesity in children.

Conclusions

Obesity and the comorbidity of MASLD is increasing in children, and this is a medical problem that needs to be addressed urgently. It is well known that children with metabolic associated chronic disease often continue to have these chronic diseases as adults, which leads to reduced life expectancy, quality of life, and increasing healthcare needs and financial burden. The authors of this paper recommend healthy weight reduction not only through lifestyle modification but through obesity pharmacotherapy and bariatric surgery. Therefore, this guidance reviews available therapies to achieve healthy weight reduction and reverse MASLD to prevent progressive liver fibrosis, and metabolic disease.

Inverted day-night feeding during pregnancy affects the brain health of both maternal and fetal brains through increasing inflammation levels associated with dysbiosis of the gut microbiome in rats

BACKGROUND

In both humans and rodents, inappropriate feeding times during pregnancy can cause maternal metabolic abnormalities, increasing the risk of neurodevelopmental disorders in both the mother and offspring. Using a rat model, this study investigates whether feeding only during the inactive phase in rats leads to anxiety-like behaviors and abnormal brain development in fetuses through gut microbiota imbalance.

METHODS

10-week-old female rats in the inactive-phase feeding group (IF group) were first trained for daytime feeding, ensuring that energy intake was statistically insignificant and different from that of the normal diet feeding group (ND group). They were then paired with male rats, and the previous feeding regimen was continued after pregnancy. Anxiety-like behavior was evaluated using the open-field test. Maternal caecal microbiota was analyzed using 16S rRNA sequencing. Enzyme-linked immunosorbent assay (ELISA) measured serum inflammation factors. RT-PCR was employed to assess mRNA levels of integrity genes and inflammatory cytokines in the maternal hippocampi, intestines, fetal brains, and placentae.

RESULTS

There were no statistically significant differences in energy intake or body weight gain between the IF and ND groups. In the open field test, dams in the IF group exhibited anxiety-like behavior, as indicated by fewer entries into and shorter duration in the central zone. Active-phase fasting elevated maternal serum inflammatory cytokine levels and impaired antioxidant capacity. It also increased intestinal permeability and induced gut microbiota dysbiosis, characterized by a decrease in Akkermansia and an increase in Dubosiella. Changes in the expression of intestinal circadian genes and elevated intestinal inflammatory cytokines were observed. Lipopolysaccharide (LPS) translocated into the maternal circulation, activated Toll-like receptor 4 (TLR 4), and passed through the compromised placental barrier into the fetal brain, leading to increased expression of inflammatory cytokines in the fetal brain.

CONCLUSIONS

The misalignment between maternal feeding time and the biological clock during pregnancy disrupts the balance of the gut microbiota and peripheral rhythms. The impaired intestinal and placental barriers allow LPS from the gut to infiltrate the maternal hippocampus and fetal brain, increasing inflammation and impacting both maternal and fetal brain health.

Potential bidirectional communication between the liver and the central circadian clock in MASLD

Most aspects of physiology and behaviour fluctuate every 24 h in mammals. These circadian rhythms are orchestrated by an autonomous central clock located in the suprachiasmatic nuclei that coordinates the timing of cellular clocks in tissues throughout the body. The critical role of this circadian system is emphasized by increasing evidence associating disruption of circadian rhythms with diverse pathologies. Accordingly, mounting evidence suggests a bidirectional relationship where disruption of rhythms by circadian misalignment may contribute to liver diseases while liver diseases alter the central clock and circadian rhythms in other tissues. Therefore, liver pathophysiology may broadly impact the circadian system and may provide a mechanistic framework for understanding and targeting metabolic diseases and adjust metabolic setpoints.

The cyclic metabolic switching theory of intermittent fasting

Intermittent fasting (IF) and ketogenic diets (KDs) have recently attracted much attention in the scientific literature and in popular culture and follow a longer history of exercise and caloric restriction (CR) research. Whereas IF involves cyclic metabolic switching (CMS) between ketogenic and non-ketogenic states, KDs and CR may not. In this Perspective, I postulate that the beneficial effects of IF result from alternating between activation of adaptive cellular stress response pathways during the fasting period, followed by cell growth and plasticity pathways during the feeding period. Thereby, I establish the cyclic metabolic switching (CMS) theory of IF. The health benefits of IF may go beyond those seen with continuous CR or KDs without CMS owing to the unique interplay between the signalling functions of the ketone β-hydroxybutyrate, mitochondrial adaptations, reciprocal activation of autophagy and mTOR pathways, endocrine and paracrine signalling, gut microbiota, and circadian biology. The CMS theory may have important implications for future basic research, clinical trials, development of pharmacological interventions, and healthy lifestyle practices.

Circadian clock communication during homeostasis and ageing

Maintaining homeostasis is essential for continued health, and the progressive decay of homeostatic processes is a hallmark of ageing. Daily environmental rhythms threaten homeostasis, and circadian clocks have evolved to execute physiological processes in a manner that anticipates, and thus mitigates, their effects on the organism. Clocks are active in almost all cell types; their rhythmicity and functional output are determined by a combination of tissue-intrinsic and systemic inputs. Numerous inputs for a specific tissue are produced by the activity of circadian clocks of other tissues or cell types, generating a form of crosstalk known as clock communication. In mammals, the central clock in the hypothalamus integrates signals from external light-dark cycles to align peripheral clocks elsewhere in the body. This regulation is complemented by a tissue-specific milieu of external, systemic and niche inputs that modulate and cooperate with the cellular circadian clock machinery of a tissue to tailor its functional output. These mechanisms of clock communication decay during ageing, and growing evidence suggests that this decline might drive ageing-related morbidities. Dietary, behavioural and pharmacological interventions may offer the possibility to overcome these changes and in turn improve healthspan.

Zinc finger homeobox-3 (ZFHX3) orchestrates genome-wide daily gene expression in the suprachiasmatic nucleus

The mammalian suprachiasmatic nucleus (SCN), situated in the ventral hypothalamus, directs daily cellular and physiological rhythms across the body. The SCN clockwork is a self-sustaining transcriptional-translational feedback loop (TTFL) that in turn coordinates the expression of clock-controlled genes (CCGs) directing circadian programmes of SCN cellular activity. In the mouse, the transcription factor, ZFHX3 (zinc finger homeobox-3), is necessary for the development of the SCN and influences circadian behaviour in the adult. The molecular mechanisms by which ZFHX3 affects the SCN at transcriptomic and genomic levels are, however, poorly defined. Here, we used chromatin immunoprecipitation sequencing to map the genomic localization of ZFHX3-binding sites in SCN chromatin. To test for function, we then conducted comprehensive RNA sequencing at six distinct times-of-day to compare the SCN transcriptional profiles of control and ZFHX3-conditional null mutants. We show that the genome-wide occupancy of ZFHX3 occurs predominantly around gene transcription start sites, co-localizing with known histone modifications, and preferentially partnering with clock transcription factors (CLOCK, BMAL1) to regulate clock gene(s) transcription. Correspondingly, we show that the conditional loss of ZFHX3 in the adult has a dramatic effect on the SCN transcriptome, including changes in the levels of transcripts encoding elements of numerous neuropeptide neurotransmitter systems while attenuating the daily oscillation of the clock TF Bmal1. Furthermore, various TTFL genes and CCGs exhibited altered circadian expression profiles, consistent with an advanced in daily behavioural rhythms under 12 h light-12 h dark conditions. Together, these findings reveal the extensive genome-wide regulation mediated by ZFHX3 in the central clock that orchestrates daily timekeeping in mammals.

Unraveling the Health Benefits and Mechanisms of Time-Restricted Feeding: Beyond Caloric Restriction

Time-restricted feeding (TRF) is a lifestyle intervention that aims to maintain a consistent daily cycle of feeding and fasting to support robust circadian rhythms. Recently, it has gained scientific, medical, and public attention due to its potential to enhance body composition, extend lifespan, and improve overall health, as well as induce autophagy and alleviate symptoms of diseases like cardiovascular diseases, type 2 diabetes, neurodegenerative diseases, cancer, and ischemic injury. However, there is still considerable debate on the primary factors that contribute to the health benefits of TRF. Despite not imposing strict limitations on calorie intake, TRF consistently led to reductions in calorie intake. Therefore, while some studies suggest that the health benefits of TRF are primarily due to caloric restriction (CR), others argue that the key advantages of TRF arise not only from CR but also from factors like the duration of fasting, the timing of the feeding period, and alignment with circadian rhythms. To elucidate the roles and mechanisms of TRF beyond CR, this review incorporates TRF studies that did not use CR, as well as TRF studies with equivalent energy intake to CR, which addresses the previous lack of comprehensive research on TRF without CR and provides a framework for future research directions.

The Interplay of Genetic Predisposition, Circadian Misalignment, and Metabolic Regulation in Obesity

PURPOSE OF REVIEW

This review explores the complex interplay between genetic predispositions to obesity, circadian rhythms, metabolic regulation, and sleep. It highlights how genetic factors underlying obesity exacerbate metabolic dysfunction through circadian misalignment and examines promising interventions to mitigate these effects.

RECENT FINDINGS

Genome-wide association Studies (GWAS) have identified numerous Single Nucleotide Polymorphisms (SNPs) associated with obesity traits, attributing 40-75% heritability to body mass index (BMI). These findings illuminate critical links between genetic obesity, circadian clocks, and metabolic processes. SNPs in clock-related genes influence metabolic pathways, with disruptions in circadian rhythms-driven by poor sleep hygiene or erratic eating patterns-amplifying metabolic dysfunction. Circadian clocks, synchronized with the 24-h light-dark cycle, regulate key metabolic activities, including glucose metabolism, lipid storage, and energy utilization. Genetic mutations or external disruptions, such as irregular sleep or eating habits, can destabilize circadian rhythms, promoting weight gain and metabolic disorders. Circadian misalignment in individuals with genetic predispositions to obesity disrupts the release of key metabolic hormones, such as leptin and insulin, impairing hunger regulation and fat storage. Interventions like time-restricted feeding (TRF) and structured physical activity offer promising strategies to restore circadian harmony, improve metabolic health, and mitigate obesity-related risks.

Circadian Disruption and the Risk of Developing Obesity

PURPOSE OF THE REVIEW

This review summarizes recent evidence for a role of the clock in adipose tissue physiology and the impact of circadian desynchrony on the development of obesity.

RECENT FINDINGS

Circadian disruptions due to shift work, late time eating and nighttime light exposure are associated with obesity and its metabolic and cardiovascular consequences. Studies in mice harboring tissue-specific gain/loss of function mutations in clock genes revealed that the circadian clock acts on multiple pathways to control adipogenesis, lipogenesis/lipolysis and thermogenesis. Time-restricted eating (TRE), aligning feeding with the active period to restore clock function, represents a promising strategy to curb obesity. While TRE has shown clear benefits, especially in participants at higher cardiometabolic risk, current studies are limited in size and duration. Larger, well-controlled studies are warranted to conclusively assess the effects of TRE in relation to the metabolic status and gender. Field studies in shift-workers, comparing permanent night shift versus rotating shifts, are also necessary to identify the optimal time window for TRE.

Twelve-hour ultradian rhythmic reprogramming of gene expression in the human ovary during aging

BACKGROUND

The 12-h ultradian rhythm plays a crucial role in metabolic homeostasis, but its role in ovarian aging has not been explored. This study investigates age-related changes in 12-h rhythmic gene expression across various human tissues, with a particular focus on the ovary.

METHODS

We analyzed transcriptomic data from the GTEx project to examine 12-h ultradian rhythmic gene expression across multiple peripheral human tissues, exploring sex-specific patterns and age-related reprogramming of both 12-h and 24-h rhythmic gene expression.

RESULTS

Our findings revealed sex-dimorphic patterns in 12-h rhythmic gene expression, with females exhibiting stronger 12-h rhythms than males. Midlife (ages 40-49) was identified as a critical period for the reprogramming of both 12-h and 24-h rhythmic gene expression. The ovary was notable among other organs due to its high number of genes exhibiting 12-h rhythmic expression and a distinct pattern of rhythmic gene expression reprogramming during aging. This reprogramming involved two gene subsets: one subset adopted de novo 12-h rhythms, while another subset shifted from 24-h rhythms in younger individuals to dual 12-h and 24-h rhythms in middle-aged individuals. Both subsets were primarily associated with angiogenesis.

CONCLUSIONS

This study is the first to report age-related reprogramming of 12-h rhythms in human tissues, with a particular focus on the amplification of 12-h rhythms in angiogenesis-related genes in the aging ovary. These findings provide novel insights into the mechanisms structured format of the abstract text underlying ovarian aging and suggest potential therapeutic strategies targeting rhythmic gene expression in the ovary.

Ketogenic diet combined with intermittent fasting: an option for type 2 diabetes remission?

With increasing attention to diabetes remission, various special dietary patterns have been found to be effective in achieving diabetes remission. The effect of a single dietary pattern on lowering blood glucose is clear, but studies on the synergistic effects of different dietary patterns are limited. This article describes the types of intermittent fasting and ketogenic diets, potential mechanisms, contraindications of combination diets, recommendations for combination diets, and their health outcomes. This paper aims to illustrate the evidence for intermittent fasting combined with a ketogenic diet on outcomes of diabetes remission and effect on blood glucose control. Knowledge of these findings can help doctors and patients determine dietary patterns for achieving diabetes remission and understanding their application.

Feeding disruptions lead to a significant increase in disease modules in adult mice

Feeding disruption is closely linked to numerous diseases, yet the underlying molecular mechanisms remain an important but unresolved issue at the molecular level. We hypothesize that, at the network level, dietary disruptions can alter gene co-expression patterns, leading to an increase in disease-associated modules, and thereby elevating the likelihood of disease occurrence. Here, we investigate this hypothesis using transcriptomic data from a large cohort of adult mice subjected to feeding disruptions. Our computational analysis indicates that altered feeding schedules significantly increase disease-related modules in adult mouse livers, well before aging and disease onset. Conversely, calorie restriction significantly reduces these disease modules. This provides a critical missing link between feeding disruption and the molecular mechanisms of disease.

Time-restricted feeding modulates gene expression related with rhythm and inflammation in Mongolian gerbils

Time-restricted feeding (TRF) has the potential to modulate circadian rhythm and widely studied in humans and laboratory mice. However, less is known about the physiological responses to TRF in wild mammals. Here, we used Mongolian gerbils, Meriones unguiculatus, to explore the effect of 6-week TRF on gene expression related with circadian rhythm and inflammation. The TRF gerbils had higher cumulative food intake than the ad libitum (AL) group, but body mass, feeding frequency/time and metabolic rate did not differ between groups. In the hypothalamus, downregulation of rhythm-related genes Per3, Cry1 and Dbp was detected in the daytime-restricted feeding (DRF) group and Cry1 was downregulated in the nighttime-restricted feeding (NRF) group. In the liver, the expression of Per1/3, Rev-erbα/β and Dbp was lower, and Bmal1 was higher in the DRF than in AL group, while NRF gerbils showed no changes. In the colon, the expression of Bmal1 and Cry1 was higher but Per3, Rev-erbα/β and Dbp were lower in the DRF than in AL group. Further, the expression of inflammation-related genes such as NF-κB, IL-1β, IL-18 and Nlrp3 was lower in the liver of DRF gerbils, and IL-1β was lower both in the hypothalamus and liver of NRF gerbils. Moreover, the genes related with inflammation such as NF-κB, Nlrp3, IL-10/18/1β and Tnf-α were positively or negatively correlated with multiple rhythm-related genes in the central and peripheral organs. In conclusion, TRF, particularly DRF, could modulate rhythm-related genes in the central and peripheral tissues and reduce hepatic expression of inflammation-related genes in gerbils.

Genetic synchronization of the brain and liver molecular clocks defend against chrono-metabolic disease

Nearly every cell of the body contains a circadian clock mechanism that is synchronized with the light-entrained clock in the suprachiasmatic nucleus (SCN). Desynchrony between the SCN and the external environment leads to metabolic dysfunction in shift workers. Similarly, mice with markedly shortened endogenous period due to the deletion of circadian REV-ERBα/β nuclear receptors in the SCN (SCN DKO) exhibit increased sensitivity to diet-induced obesity (DIO) on a 24 h light:dark cycle while mice with REV-ERBs deleted in hepatocytes (HepDKO) display exacerbated hepatosteatosis in response to a high-fat diet. Here, we show that inducing deletion of hepatocyte REV-ERBs in SCN DKO mice (Hep-SCN DDKO) rescued the exacerbated DIO and hepatic triglyceride accumulation, without affecting the shortened behavioral period. These findings suggest that metabolic disturbances due to environmental desynchrony with the central clock are due to effects on peripheral clocks which can be mitigated by matching peripheral and central clock periods even in a desynchronous environment. Thus, maintaining synchrony within an organism, rather than between endogenous and exogenous clocks, may be a viable target for the treatment of metabolic disorders associated with circadian disruption.

Impacts of dietary fat on multi tissue gene expression in the desert-adapted cactus mouse

Understanding the relationship between dietary fat and physiological responses is crucial in species adapted to arid environments where water scarcity is common. In this study, we present a comprehensive exploration of gene expression across five tissues (kidney, liver, lung, gastrointestinal tract and hypothalamus) and 17 phenotypic measurements, investigating the effects of dietary fat in the desert-adapted cactus mouse (Peromyscus eremicus). We show impacts on immune function, circadian gene regulation and mitochondrial function for mice fed a lower-fat diet compared with mice fed a higher-fat diet. In arid environments with severe water scarcity, even subtle changes in organismal health and water balance can affect physical performance, potentially impacting survival and reproductive success. This study sheds light on the complex interplay between diet, physiological processes and environmental adaptation, providing valuable insights into the multifaceted impacts of dietary choices on organismal well-being and adaptation strategies in arid habitats.

Different time-restricted feeding patterns potentially modulate metabolic health by altering tryptophan metabolism of gut microbes in pigs

Time-restricted feeding has emerged as a preferred approach for alleviating metabolic disorders, but the potential microbiological mechanism remains poorly understood. This study used a growing pig model to mimic common-sense eating habits. Four feeding patterns were set up, including ad libitum feeding (ALF) for daily irregulated eating habits, time-restricted feeding (TRF) for three meals a day, early time-restricted feeding (eTRF) for skipping dinner and mid-day time-restricted feeding (mTRF) for skipping breakfast. The results showed that the three time-restricted feeding patterns (TRF, eTRF and mTRF) resulted in a reduction of hepatic fat accumulation and a decrease in hepatic function markers compared to the ALF pattern. However, this was independent of food consumption. Transcriptome analysis of the liver showed that the three time-restricted feeding patterns downregulated the expression of genes related to gluconeogenesis, β-oxidation, lipid accumulation, and urea cycle, and upregulated the expression of genes related to lipogenesis and glycolysis compared to the ALF pattern. Microbiome and metabolome analyses showed that Lactobacillus enriched in the colon of pigs in three time-restricted groups were negatively correlated with serum triglyceride. Meanwhile, three time-restricted feeding patterns elevated the levels of the microbial metabolite indole-3-lactic acid, which was further confirmed to reduce excessive hepatic lipid accumulation in vitro. Overall, time-restricted feeding potentially improved metabolic health by modulating gut microbiota and metabolites.

Onset of circadian rhythmicity in the brain of Atlantic salmon is linked to exogenous feeding

An organism's biological processes are adapted to and driven by rhythmicity in the natural environment and periodicity of light is one of the most influential factors. In a developing organism, the onset of circadian rhythmicity might indicate the time point of functional necessity for aligning processes to the environment. Here, the circadian clock mechanism has been studied in the developing brain of Atlantic salmon (Salmo salar), by comparing the endogenous feeding alevin, independent on the environment for nutritional supply, to the exogenous feeding fry, dependent on the light period for detecting and catching prey. The results showed that while only a few clock genes were cyclic in the yolk sac alevins, many of the clock genes and genes of the circadian rhythm pathway cycled significantly in the feeding fry. Few genes were differentially expressed between time points in the circadian sampling series during the yolk sac stage, but several hundred genes were found differentially expressed in the first feeding stage. Genes important for cell cycle progression were cyclic or differentially expressed between time points after exogenous feeding, indicating a clock-controlled cell cycle at this stage. The expression of important genes in the melatonin synthesis were also cyclic in the feeding fry with an acrophase in the transition between light and dark or in darkness. Analyzing the impact of exogenous feeding on the developing brain supported a shift from utilization of proteins and lipids in the yolk to utilization and allocation of dietary energy and nutrients. Taken together, the life history transition related to onset of exogenous feeding is linked to the establishment of a persistent circadian rhythmicity in the salmon brain, which needs to be synchronized to light-dark cycles to enable the fry to search and capture feed.

Cysteine protease cathepsin B promotes lysosome integrity to extend the lifespan of alternative day fasting worms

Alternative day fasting (ADF) has been shown to enhance the lifespan of animals. However, human trials evaluating the efficacy of ADF have only recently emerged, presenting challenges due to the extreme nature of this dietary regimen. To better understand the effects of ADF, we investigated its impact using Caenorhabditis elegans as a model organism. Our findings reveal that ADF extends the lifespan of worms nourished on animal-based protein source, while those fed with plant-based protein as the primary protein source do not experience such benefits. Remarkably, initiating ADF during midlife is sufficient to prolong lifespan, whereas implementation during youth results in developmental damage, and in older age, fails to provide additional extension effects. Furthermore, we discovered that midlife ADF up-regulates the expression of two cysteine protease cathepsin B genes, cpr-2 and cpr-5, which preserve lysosomal integrity and enhance its function in digesting aggregated proteins, as well as enhancing lipid metabolism and ameliorating neurodegenerative disease markers and phenomena during aging. This suggests that midlife ADF has long lasting anti-aging effects and may delay the onset of related diseases, specifically in animals consuming animal-based protein source. These findings offer valuable insights into the effects of ADF and provide guidance for future research and potential applications in individuals.

Disruption of the intestinal clock drives dysbiosis and impaired barrier function in colorectal cancer

Diet is a robust entrainment cue that regulates diurnal rhythms of the gut microbiome. We and others have shown that disruption of the circadian clock drives the progression of colorectal cancer (CRC). While certain bacterial species have been suggested to play driver roles in CRC, it is unknown whether the intestinal clock impinges on the microbiome to accelerate CRC pathogenesis. To address this, genetic disruption of the circadian clock, in an Apc-driven mouse model of CRC, was used to define the impact on the gut microbiome. When clock disruption is combined with CRC, metagenomic sequencing identified dysregulation of many bacterial genera including Bacteroides, Helicobacter, and Megasphaera. We identify functional changes to microbial pathways including dysregulated nucleic acid, amino acid, and carbohydrate metabolism, as well as disruption of intestinal barrier function. Our findings suggest that clock disruption impinges on microbiota composition and intestinal permeability that may contribute to CRC pathogenesis.

Time-Restricted Feeding Reduces Atherosclerosis in LDLR KO Mice but Not in ApoE Knockout Mice

BACKGROUND

Dyslipidemia increases cardiovascular disease risk, the leading cause of death worldwide. Under time-restricted feeding (TRF), wherein food intake is restricted to a consistent window of <12 hours, weight gain, glucose intolerance, inflammation, dyslipidemia, and hypercholesterolemia are all reduced in mice fed an obesogenic diet. LDLR (low-density lipoprotein receptor) mutations are a major cause of familial hypercholesterolemia and early-onset cardiovascular disease.

METHODS

We subjected benchmark preclinical models, mice lacking LDLR-knockout or ApoE knockout to ad libitum feeding of an isocaloric atherogenic diet either ad libitum or 9 hours TRF for up to 13 weeks and assessed disease development, mechanism, and global changes in hepatic gene expression and plasma lipids. In a regression model, a subset of LDLR-knockout mice were ad libitum fed and then subject to TRF.

RESULTS

TRF could significantly attenuate weight gain, hypercholesterolemia, and atherosclerosis in mice lacking the LDLR-knockout mice under experimental conditions of both prevention and regression. In LDLR-knockout mice, increased hepatic expression of genes mediating β-oxidation during fasting is associated with reduced VLDL (very-low-density lipoprotein) secretion and lipid accumulation. Additionally, increased sterol catabolism coupled with fecal loss of cholesterol and bile acids contributes to the atheroprotective effect of TRF. Finally, TRF alone or combined with a cholesterol-free diet can reduce atherosclerosis in LDLR-knockout mice. However, mice lacking ApoE, which is an important protein for hepatic lipoprotein reuptake do not respond to TRF.

CONCLUSIONS

In a preclinical animal model, TRF is effective in both the prevention and regression of atherosclerosis in LDLR knockout mice. The results suggest TRF alone or in combination with a low-cholesterol diet can be a lifestyle intervention for reducing cardiovascular disease risk in humans.

Long-term high fructose intake reprograms the circadian transcriptome and disrupts homeostasis in mouse extra-orbital lacrimal glands

This study aims to explore the effects of long-term high fructose intake (LHFI) on the structure, functionality, and physiological homeostasis of mouse extra-orbital lacrimal glands (ELGs), a critical component of ocular health. Our findings reveal significant reprogramming of the circadian transcriptome in ELGs following LHFI, alongside the activation of specific inflammatory pathways, as well as metabolic and neural pathways. Notably, LHFI resulted in increased inflammatory infiltration, enhanced lipid deposition, and reduced nerve fiber density in ELGs compared to controls. Functional assessments indicated a marked reduction in lacrimal secretion following cholinergic stimulation in LHFI-treated mice, suggesting impaired gland function. Overall, our results suggest that LHFI disrupts lacrimal gland homeostasis, potentially leading to dry eye disease by altering its structure and secretory function. These insights underscore the profound impact of dietary choices on ocular health and highlight the need for strategies to mitigate these risks.

Circadian Interventions in Preclinical Models of Huntington's Disease: A Narrative Review

Huntington's Disease (HD) is a neurodegenerative disorder caused by an autosomal-dominant mutation in the huntingtin gene, which manifests with a triad of motor, cognitive and psychiatric declines. Individuals with HD often present with disturbed sleep/wake cycles, but it is still debated whether altered circadian rhythms are intrinsic to its aetiopathology or a consequence. Conversely, it is well established that sleep/wake disturbances, perhaps acting in concert with other pathophysiological mechanisms, worsen the impact of the disease on cognitive and motor functions and are a burden to the patients and their caretakers. Currently, there is no cure to stop the progression of HD, however, preclinical research is providing cementing evidence that restoring the fluctuation of the circadian rhythms can assist in delaying the onset and slowing progression of HD. Here we highlight the application of circadian-based interventions in preclinical models and provide insights into their potential translation in clinical practice. Interventions aimed at improving sleep/wake cycles' synchronization have shown to improve motor and cognitive deficits in HD models. Therefore, a strong support for their suitability to ameliorate HD symptoms in humans emerges from the literature, albeit with gaps in our knowledge on the underlying mechanisms and possible risks associated with their implementation.

Targeting the intestinal circadian clock by meal timing ameliorates gastrointestinal inflammation

The expression of clock genes has been observed to be impaired in biopsies from patients with inflammatory bowel disease (IBD). Disruption of circadian rhythms, which occurs in shift workers, has been linked to an increased risk of gastrointestinal diseases, including IBD. The peripheral circadian clock in intestinal epithelial cells (IECs) was previously shown to balance gastrointestinal homeostasis by regulating the microbiome. Here, we demonstrated that the intestinal clock is disrupted in an IBD-relevant mouse model (IL-10-/-). A lack of the intestinal clock gene (Bmal1) in intestinal epithelial cells (IECs) in a chemically and a novel genetically induced colitis model (DSS, Bmal1IEC-/-xIL-10-/-) promoted colitis and dramatically reduced survival rates. Germ-free Bmal1IEC-/- mice colonized with disease-associated microbiota from IL-10-/- mice exhibited increased inflammatory responses, highlighting the importance of the local intestinal clock for microbiota-induced IBD development. Targeting the intestinal clock directly by timed restricted feeding (RF) in IL-10-/- mice restored intestinal clock functions, including immune cell recruitment and microbial rhythmicity; improved inflammatory responses; dramatically enhanced survival rates and rescued the histopathological phenotype. In contrast, RF failed to improve IBD symptoms in Bmal1IEC-/-xIL-10-/- mice, demonstrating the significance of the intestinal clock in determining the beneficial effect of RF. Overall, we provide evidence that intestinal clock dysfunction triggers host immune imbalance and promotes the development and progression of IBD-like colitis. Enhancing intestinal clock function by RF modulates the pathogenesis of IBD and thus could become a novel strategy to ameliorate symptoms in IBD patients.

Diurnal expression of Dgat2 induced by time-restricted feeding maintains cardiac health in the Drosophila model of circadian disruption

Circadian disruption is associated with an increased risk of cardiometabolic disorders and cardiac diseases. Time-restricted feeding/eating (TRF/TRE), restricting food intake within a consistent window of the day, has shown improvements in heart function from flies and mice to humans. However, whether and how TRF still conveys cardiac benefits in the context of circadian disruption remains unclear. Here, we demonstrate that TRF sustains cardiac performance, myofibrillar organization, and regulates cardiac lipid accumulation in Drosophila when the circadian rhythm is disrupted by constant light. TRF induces oscillations in the expression of genes associated with triglyceride metabolism. In particular, TRF induces diurnal expression of diacylglycerol O-acyltransferase 2 (Dgat2), peaking during the feeding period. Heart-specific manipulation of Dgat2 modulates cardiac function and lipid droplet accumulation. Strikingly, heart-specific overexpression of human Dgat2 at ZT 0-10 significantly improves cardiac performance in flies exposed to constant light. We have demonstrated that TRF effectively attenuates cardiac decline induced by circadian disruption. Moreover, our data suggests that diurnal expression of Dgat2 induced by TRF is beneficial for heart health under circadian disruption. Overall, our findings have underscored the relevance of TRF in preserving heart health under circadian disruptions and provided potential targets, such as Dgat2, and strategies for therapeutic interventions in mitigating cardiac aging, metabolic disorders, and cardiac diseases in humans.

Pioneering new frontiers in circadian medicine chronotherapies for cardiovascular health

Cardiovascular disease (CVD) is a global health concern. Circadian medicine improves cardiovascular care by aligning treatments with our body's daily rhythms and their underlying cellular circadian mechanisms. Time-based therapies, or chronotherapies, show special promise in clinical cardiology. They optimize treatment schedules for better outcomes with fewer side effects by recognizing the profound influence of rhythmic body cycles. In this review, we focus on three chronotherapy areas (medication, light, and meal timing) with potential to enhance cardiovascular care. We also highlight pioneering research in the new field of rest, the gut microbiome, novel chronotherapies for hypertension, pain management, and small molecules that targeting the circadian mechanism.

Intermittent Metabolic Switching and Vascular Cognitive Impairment

Intermittent fasting (IF), a dietary pattern alternating between eating and fasting periods within a 24-hour cycle, has garnered recognition for its potential to enhance both healthspan and lifespan in animal models and humans. It also shows promise in alleviating age-related diseases, including neurodegeneration. Vascular cognitive impairment (VCI) spans a severity range from mild cognitive deficits to severe cognitive deficits and loss of function in vascular dementia. Chronic cerebral hypoperfusion has emerged as a significant contributor to VCI, instigating vascular pathologies such as microbleeds, blood-brain barrier dysfunction, neuronal loss, and white matter lesions. Preclinical studies in rodents strongly suggest that IF has the potential to attenuate pathological mechanisms, including excitotoxicity, oxidative stress, inflammation, and cell death pathways in VCI models. Hence, this supports evaluating IF in clinical trials for both existing and at-risk VCI patients. This review compiles existing data supporting IF's potential in treating VCI-related vascular and neuronal pathologies, emphasizing the mechanisms by which IF may mitigate these issues. Hence providing a comprehensive overview of the available data supporting IF's potential in treating VCI by emphasizing the underlying mechanisms that make IF a promising intervention for VCI.

Transcriptional response to an alternative diet on liver, muscle, and rumen of beef cattle

Feed cost represents a major economic determinant within cattle production, amounting to an estimated 75% of the total variable costs. Consequently, comprehensive approaches such as optimizing feed utilization through alternative feed sources, alongside the selection of feed-efficient animals, are of great significance. Here, we investigate the effect of two diets, traditional corn-grain fed and alternative by-product based, on 14 phenotypes related to feed, methane emission and production efficiency and on multi-tissue transcriptomics data from liver, muscle, and rumen wall, derived from 52 Nellore bulls, 26 on each diet. To this end, diets were contrasted at the level of phenotype, gene expression, and gene-phenotype network connectivity. As regards the phenotypic level, at a P value < 0.05, significant differences were found in favour of the alternative diet for average daily weight gain at finishing, dry matter intake at finishing, methane emission, carcass yield and subcutaneous fat thickness at the rib-eye muscle area. In terms of the transcriptional level of the 14,776 genes expressed across the examined tissues, we found 487, 484, and 499 genes differentially expressed due to diet in liver, muscle, and rumen, respectively (P value < 0.01). To explore differentially connected phenotypes across both diet-based networks, we focused on the phenotypes with the largest change in average number of connections within diets and tissues, namely methane emission and carcass yield, highlighting, in particular, gene expression changes involving SREBF2, and revealing the largest differential connectivity in rumen and muscle, respectively. Similarly, from examination of differentially connected genes across diets, the top-ranked most differentially connected regulators within each tissue were MEOX1, PTTG1, and BASP1 in liver, muscle, and rumen, respectively. Changes in gene co-expression patterns suggest activation or suppression of specific biological processes and pathways in response to dietary interventions, consequently impacting the phenotype. The identification of genes that respond differently to diets and their associated phenotypic effects serves as a crucial stepping stone for further investigations, aiming to build upon our discoveries. Ultimately, such advancements hold the promise of improving animal welfare, productivity, and sustainability in livestock farming.

Non-rhythmic modulators of the circadian system: A new class of circadian modulators

The temporal organization of biological processes is critical for an organism's fitness and survival. An internal circadian clock network coordinates the alignment between the external and internal milieus via an array of systemic factors carrying temporal information such as core body temperature, autonomic activity, hormonal secretion, and behavioral functions. Collectively, these so called zeitgebers are characterized by strong temporal variations (i.e., high amplitudes). At the same time, target tissues show time windows of highest and lowest sensitivity to specific zeitgebers and, in this way, tissues can further modulate the effect of zeitgeber input in a process known as circadian gating. Such interplay between systemic signals and local circadian gating, however, suggests an additional level of temporal control-the resetting of target tissue rhythms in response to altered levels of tonic (i.e., non-rhythmic) signals. The recently identified tuning of liver transcriptome rhythms by thyroid hormones (THs) is one example of such regulation. THs show low-amplitude rhythms in the serum levels that are easily disrupted by altered thyroid states. At the same time, circadian rhythms in TH target tissues, such as liver, are markedly affected by alterations in TH state. Temporal regulation of TH target genes in other tissues suggests similar effects across the body. This chapter describes the rationale, experimental evidence, and potential consequences of this new level of circadian regulators.

Sexual dimorphism of circadian liver transcriptome

Sexual dimorphism affects various aspects of physiology, metabolism and longevity. Circadian clock is a master regulator of metabolism. Anti-aging dietary interventions reprogram circadian transcriptome in the liver and other tissues, but little is known about sexual dimorphism of circadian transcriptome. We compared circadian transcriptomes in the liver of male and female mice on ad libitum (AL) and 30% caloric restriction (CR) diets. We found that AL female mice had a larger number of oscillating genes than male mice, and the portion of the transcriptome with sex-specific rhythms displayed phase difference. We found that CR increased the number of oscillating genes in both sexes and strongly synchronized the transcriptome without complete elimination of sex dimorphism in rhythms. Sex also had an effect on the response of the rhythms to CR. Gene ontology analysis revealed sex-specific signatures in metabolic pathways, which suggests a complex interaction of sex, circadian rhythms, and diet.

Time-restricted feeding prevents ionizing radiation-induced hematopoietic stem cell damage by inhibiting NOX-4/ROS/p38 MAPK pathway

Ionizing radiation (IR)-induced damage to the hematopoietic system is a prominent symptom following exposure to total body irradiation (TBI). The exploration of strategies aimed at to mitigating radiation-induced hematopoietic damage assumes paramount importance. Time-restricted feeding (TRF) has garnered attention for its beneficial effects in various diseases. In this study, we evaluated the preventive effects of TRF on TBI-induced hematopoietic damage. The results suggested that TRF significantly enhanced the proportion and function of hematopoietic stem cells in mice exposed to 4 Gy TBI. These effects might be attributed to the inhibition of the NOX-4/ROS/p38 MAPK pathway in hematopoietic stem cells. TRF also influenced the expression of nuclear factor erythroid2-related factor 2 and increased glutathione peroxidase activity, thereby promoting the clearance of reactive oxygen species. Furthermore, TRF alleviated aberrations in plasma metabolism by inhibiting the mammalian target of rapamycin. These findings suggest that TRF may represent a novel approach to preventing hematopoietic radiation damage.

Energy balance drives diurnal and nocturnal brain transcriptome rhythms

Plasticity in daily timing of activity has been observed in many species, yet the underlying mechanisms driving nocturnality and diurnality are unknown. By regulating how much wheel-running activity will be rewarded with a food pellet, we can manipulate energy balance and switch mice to be nocturnal or diurnal. Here, we present the rhythmic transcriptome of 21 tissues, including 17 brain regions, sampled every 4 h over a 24-h period from nocturnal and diurnal male CBA/CaJ mice. Rhythmic gene expression across tissues comprised different sets of genes with minimal overlap between nocturnal and diurnal mice. We show that non-clock genes in the suprachiasmatic nucleus (SCN) change, and the habenula was most affected. Our results indicate that adaptive flexibility in daily timing of behavior is supported by gene expression dynamics in many tissues and brain regions, especially in the habenula, which suggests a crucial role for the observed nocturnal-diurnal switch.

Circadian Clock and Hypoxia

The timing of life on Earth is remarkable: between individuals of the same species, a highly similar temporal pattern is observed, with shared periods of activity and inactivity each day. At the individual level, this means that over the course of a single day, a person alternates between two states. They are either upright, active, and communicative or they lie down in a state of (un)consciousness called sleep where even the characteristic of neuronal signals in the brain shows distinctive properties. The circadian clock governs both of these time stamps-activity and (apparent) inactivity-making them come and go consistently at the same approximate time each day. This behavior thus represents the meeting of two pervasive systems: the circadian clock and metabolism. In this article, we will describe what is known about how the circadian clock anticipates daily changes in oxygen usage, how circadian clock regulation may relate to normal physiology, and to hypoxia and ischemia that can result from pathologies such as myocardial infarction and stroke.

Extensive dynamic changes in the human transcriptome and its circadian organization during prolonged bed rest

Physiological and molecular processes including the transcriptome change across the 24-h day, driven by molecular circadian clocks and behavioral and systemic factors. It is not known how the temporal organization of the human transcriptome responds to a long-lasting challenge. This may, however, provide insights into adaptation, disease, and recovery. We investigated the human 24-h time series transcriptome in 20 individuals during a 90-day constant bed rest protocol. We show that the protocol affected 91% of the transcriptome with 76% of the transcriptome still affected after 10 days of recovery. Dimensionality-reduction approaches revealed that many affected transcripts were associated with mRNA translation and immune function. The number, amplitude, and phase of rhythmic transcripts, including clock genes, varied significantly across the challenge. These findings of long-lasting changes in the temporal organization of the transcriptome have implications for understanding the mechanisms underlying health consequences of conditions such as microgravity and bed rest.

Mitochondrial Dysfunction: A Key Player in Brain Aging and Diseases

Mitochondria are thought to have become incorporated within the eukaryotic cell approximately 2 billion years ago and play a role in a variety of cellular processes, such as energy production, calcium buffering and homeostasis, steroid synthesis, cell growth, and apoptosis, as well as inflammation and ROS production. Considering that mitochondria are involved in a multitude of cellular processes, mitochondrial dysfunction has been shown to play a role within several age-related diseases, including cancers, diabetes (type 2), and neurodegenerative diseases, although the underlying mechanisms are not entirely understood. The significant increase in lifespan and increased incidence of age-related diseases over recent decades has confirmed the necessity to understand the mechanisms by which mitochondrial dysfunction impacts the process of aging and age-related diseases. In this review, we will offer a brief overview of mitochondria, along with structure and function of this important organelle. We will then discuss the cause and consequence of mitochondrial dysfunction in the aging process, with a particular focus on its role in inflammation, cognitive decline, and neurodegenerative diseases, such as Huntington's disease, Parkinson's disease, and Alzheimer's disease. We will offer insight into therapies and interventions currently used to preserve or restore mitochondrial functioning during aging and neurodegeneration.

Learning from circadian rhythm to transform cancer prevention, prognosis, and survivorship care

Circadian timekeeping mechanisms and cell cycle regulation share thematic biological principles in responding to signals, repairing cellular damage, coordinating metabolism, and allocating cellular resources for optimal function. Recent studies show interactions between cell cycle regulators and circadian clock components, offering insights into potential cancer treatment approaches. Understanding circadian control of metabolism informs timing for therapies to reduce adverse effects and enhance treatment efficacy. Circadian adaptability to lifestyle factors, such as activity, sleep, and nutrition sheds light on their impact on cancer. Leveraging circadian regulatory mechanisms for cancer prevention and care is vital, as most risk stems from modifiable lifestyles. Monitoring circadian factors aids risk assessment and targeted interventions across the cancer care continuum.

Obesity and Leukemia: Biological Mechanisms, Perspectives, and Challenges

PURPOSE OF REVIEW

To examine the epidemiological data on obesity and leukemia; evaluate the effect of obesity on leukemia outcomes in childhood acute lymphoblastic leukemia (ALL) survivors; assess the potential mechanisms through which obesity may increase the risk of leukemia; and provide the effects of obesity management on leukemia. Preventive (diet, physical exercise, obesity pharmacotherapy, bariatric surgery) measures, repurposing drugs, candidate therapeutic agents targeting oncogenic pathways of obesity and insulin resistance in leukemia as well as challenges of the COVID-19 pandemic are also discussed.

RECENT FINDINGS

Obesity has been implicated in the development of 13 cancers, such as breast, endometrial, colon, renal, esophageal cancers, and multiple myeloma. Leukemia is estimated to account for approximately 2.5% and 3.1% of all new cancer incidence and mortality, respectively, while it represents the most frequent cancer in children younger than 5 years. Current evidence indicates that obesity may have an impact on the risk of leukemia. Increased birthweight may be associated with the development of childhood leukemia. Obesity is also associated with worse outcomes and increased mortality in leukemic patients. However, there are several limitations and challenges in meta-analyses and epidemiological studies. In addition, weight gain may occur in a substantial number of childhood ALL survivors while the majority of studies have documented an increased risk of relapse and mortality among patients with childhood ALL and obesity. The main pathophysiological pathways linking obesity to leukemia include bone marrow adipose tissue; hormones such as insulin and the insulin-like growth factor system as well as sex hormones; pro-inflammatory cytokines, such as IL-6 and TNF-α; adipocytokines, such as adiponectin, leptin, resistin, and visfatin; dyslipidemia and lipid signaling; chronic low-grade inflammation and oxidative stress; and other emerging mechanisms. Obesity represents a risk factor for leukemia, being among the only known risk factors that could be prevented or modified through weight loss, healthy diet, and physical exercise. Pharmacological interventions, repurposing drugs used for cardiometabolic comorbidities, and bariatric surgery may be recommended for leukemia and obesity-related cancer prevention.

Regulation of headache response and transcriptomic network by the trigeminal ganglion clock

OBJECTIVE

To characterize the circadian features of the trigeminal ganglion in a mouse model of headache.

BACKGROUND

Several headache disorders, such as migraine and cluster headache, are known to exhibit distinct circadian rhythms of attacks. The circadian basis for these rhythmic pain responses, however, remains poorly understood.

METHODS

We examined trigeminal ganglion ex vivo and single-cell cultures from Per2::LucSV reporter mice and performed immunohistochemistry. Circadian behavior and transcriptomics were investigated using a novel combination of trigeminovascular and circadian models: a nitroglycerin mouse headache model with mechanical thresholds measured every 6 h, and trigeminal ganglion RNA sequencing measured every 4 h for 24 h. Finally, we performed pharmacogenomic analysis of gene targets for migraine, cluster headache, and trigeminal neuralgia treatments as well as trigeminal ganglion neuropeptides; this information was cross-referenced with our cycling genes from RNA sequencing data to identify potential targets for chronotherapy.

RESULTS

The trigeminal ganglion demonstrates strong circadian rhythms in both ex vivo and single-cell cultures, with core circadian proteins found in both neuronal and non-neuronal cells. Using our novel behavioral model, we showed that nitroglycerin-treated mice display circadian rhythms of pain sensitivity which were abolished in arrhythmic Per1/2 double knockout mice. Furthermore, RNA-sequencing analysis of the trigeminal ganglion revealed 466 genes that displayed circadian oscillations in the control group, including core clock genes and clock-regulated pain neurotransmitters. In the nitroglycerin group, we observed a profound circadian reprogramming of gene expression, as 331 of circadian genes in the control group lost rhythm and another 584 genes gained rhythm. Finally, pharmacogenetics analysis identified 10 genes in our trigeminal ganglion circadian transcriptome that encode target proteins of current medications used to treat migraine, cluster headache, or trigeminal neuralgia.

CONCLUSION

Our study unveiled robust circadian rhythms in the trigeminal ganglion at the behavioral, transcriptomic, and pharmacogenetic levels. These results support a fundamental role of the clock in pain pathophysiology.

PLAIN LANGUAGE SUMMARY

Several headache diseases, such as migraine and cluster headache, have headaches that occur at the same time each day. We learned that the trigeminal ganglion, an important pain structure in several headache diseases, has a 24-hour cycle that might be related to this daily cycle of headaches. Our genetic analysis suggests that some medications may be more effective in treating migraine and cluster headache when taken at specific times of the day.

Intermittent fasting and Alzheimer's disease-Targeting ketone bodies as a potential strategy for brain energy rescue

Alzheimer's disease (AD) lacks effective clinical treatments. As the disease progresses, the cerebral glucose hypometabolism that appears in the preclinical phase of AD gradually worsens, leading to increasingly severe brain energy disorders. This review analyzes the brain energy deficit in AD and its etiology, brain energy rescue strategies based on ketone intervention, the effects and mechanisms of IF, the differences in efficacy between IF and ketogenic diet and the duality of IF. The evidence suggests that brain energy deficits lead to the development and progression of AD pathology. IF, which improves brain energy impairments by promoting ketone metabolism, thus has good therapeutic potential for AD.

Time-restricted feeding ameliorates non-alcoholic fatty liver disease through modulating hepatic nicotinamide metabolism via gut microbiota remodeling

Non-alcoholic fatty liver disease (NAFLD) has emerged as a global health concern, lacking specific therapeutic strategies. Time-restricted feeding (TRF) regimen demonstrated beneficial effects in NAFLD; however, the underlying mechanisms remain unclear. In this study, we established a NAFLD mouse model through a high-fat diet (HFD) and implemented the 16:8 TRF regimen for a duration of 6 weeks. We demonstrated that TRF remarkably alleviated hepatic steatosis in HFD mice. Of note, aldehyde oxidase 1 (AOX1), a key enzyme in hepatic nicotinamide (NAM) catabolism, exhibited apparent upregulation in response to HFD, leading to abnormal accumulation of N-Methyl-6-pyridone-3-carboxamide (N-Me-6-PY, also known as 2PY) and N-Methyl-4-pyridone-5-carboxamide (N-Me-4-PY, also known as 4PY), whereas it was almost restored by TRF. Both N-Me-6-PY and N-Me-4-PY promoted de novo lipogenesis and fatty acid uptake capacities in hepatocyte, and aggravated hepatic steatosis in mice either fed chow diet or HFD. In contrast, pharmacological inhibition of AOX1 was sufficient to ameliorate the hepatic steatosis and lipid metabolic dysregulation induced by HFD. Moreover, transplantation of fecal microbiota efficiently mimicked the modulatory effect of TRF on NAM metabolism, thus mitigating hepatic steatosis and lipid metabolic disturbance, suggesting a gut microbiota-dependent manner. In conclusion, our study reveals the intricate relationship between host NAM metabolic modification and gut microbiota remodeling during the amelioration of NAFLD by TRF, providing promising insights into the prevention and treatment of NAFLD.

Time-restricted feeding regulates lipid metabolism under metabolic challenges

Dysregulation of lipid metabolism is a commonly observed feature associated with metabolic syndrome and leads to the development of negative health outcomes such as obesity, diabetes mellitus, non-alcoholic fatty liver disease, or atherosclerosis. Time-restricted feeding/eating (TRF/TRE), an emerging dietary intervention, has been shown to promote pleiotropic health benefits including the alteration of diurnal expression of genes associated with lipid metabolism, as well as levels of lipid species. Although TRF likely induces a response in multiple organs leading to the modulation of lipid metabolism, a majority of the studies related to TRF effects on lipids have focused only on individual tissues, and furthermore there is a lack of insight into potential underlying mechanisms. In this review, we summarize the current insights regarding TRF effects on lipid metabolism and the potential mechanisms in adipose tissue, liver, skeletal muscle, and heart, and conclude by outlining possible avenues for future exploration.

Time-restricted feeding and Alzheimer's disease: you are when you eat

Time-restricted feeding (TRF) has emerged as a means of synchronizing circadian rhythms, which are commonly disrupted in Alzheimer's disease (AD). Whittaker et al. demonstrate that TRF exerts protective effects in two mouse models of AD. We discuss the effects of TRF on brain health and mechanisms linking TRF to neurodegeneration.

Circadian regulation of liver metabolism: experimental approaches in human, rodent, and cellular models

Circadian rhythms are endogenous oscillations with approximately a 24-h period that allow organisms to anticipate the change between day and night. Disruptions that desynchronize or misalign circadian rhythms are associated with an increased risk of cardiometabolic disease. This review focuses on the liver circadian clock as relevant to the risk of developing metabolic diseases including nonalcoholic fatty liver disease (NAFLD), insulin resistance, and type 2 diabetes (T2D). Many liver functions exhibit rhythmicity. Approximately 40% of the hepatic transcriptome exhibits 24-h rhythms, along with rhythms in protein levels, posttranslational modification, and various metabolites. The liver circadian clock is critical for maintaining glucose and lipid homeostasis. Most of the attention in the metabolic field has been directed toward diet, exercise, and rather little to modifiable risks due to circadian misalignment or disruption. Therefore, the aim of this review is to systematically analyze the various approaches that study liver circadian pathways, targeting metabolic liver diseases, such as diabetes, nonalcoholic fatty liver disease, using human, rodent, and cell biology models.NEW & NOTEWORTHY Over the past decade, there has been an increased interest in understanding the intricate relationship between circadian rhythm and liver metabolism. In this review, we have systematically searched the literature to analyze the various experimental approaches utilizing human, rodent, and in vitro cellular approaches to dissect the link between liver circadian rhythms and metabolic disease.

Effects of exercise on circadian rhythms in humans

The biological clock system is an intrinsic timekeeping device that integrates internal physiology and external cues. Maintaining a healthy biological clock system is crucial for life. Disruptions to the body's internal clock can lead to disturbances in the sleep-wake cycle and abnormalities in hormone regulation, blood pressure, heart rate, and other vital processes. Long-term disturbances have been linked to the development of various common major diseases, including cardiovascular diseases, metabolic disorders, tumors, neuropsychiatric conditions, and so on. External factors, such as the diurnal rhythm of light, have a significant impact on the body's internal clock. Additionally, as an important non-photic zeitgeber, exercise can regulate the body's internal rhythms to a certain extent, making it possible to become a non-drug intervention for preventing and treating circadian rhythm disorders. This comprehensive review encompasses behavioral, physiological, and molecular perspectives to provide a deeper understanding of how exercise influences circadian rhythms and its association with related diseases.

Atlas of the aging mouse brain reveals white matter as vulnerable foci

Aging is the key risk factor for cognitive decline, yet the molecular changes underlying brain aging remain poorly understood. Here, we conducted spatiotemporal RNA sequencing of the mouse brain, profiling 1,076 samples from 15 regions across 7 ages and 2 rejuvenation interventions. Our analysis identified a brain-wide gene signature of aging in glial cells, which exhibited spatially defined changes in magnitude. By integrating spatial and single-nucleus transcriptomics, we found that glial aging was particularly accelerated in white matter compared with cortical regions, whereas specialized neuronal populations showed region-specific expression changes. Rejuvenation interventions, including young plasma injection and dietary restriction, exhibited distinct effects on gene expression in specific brain regions. Furthermore, we discovered differential gene expression patterns associated with three human neurodegenerative diseases, highlighting the importance of regional aging as a potential modulator of disease. Our findings identify molecular foci of brain aging, providing a foundation to target age-related cognitive decline.

Recent progress on action and regulation of anorexigenic adipokine leptin

Organismal energy balance is controlled by inter-tissue communication mediated by the nervous system and hormones, the disruption of which causes metabolic syndrome exemplified by diabetes and obesity. Fat-storing adipose tissue, especially those located in subcutaneous white adipose tissue, secretes leptin in a proportion of fat mass, inhibiting the accumulation of organismal fat by suppressing appetite and promoting energy expenditure. With a prevalence of obesity that exhibits hyperleptinemia, most of the investigation on leptin has been focused on how it works and how it does not, which is expected to be a clue for treating obesity. In contrast, how it is synthesized, transported, and excreted, all of which are relevant to the homeostasis of blood leptin concentration, are not much understood. Of note, acute leptin reduction after hyperleptinemia in the context of obesity exhibited a beneficial effect on obesity and insulin sensitivity, indicating that manipulation of circulating leptin level may provide a therapeutic strategy. Technological advances such as "omics" analysis combined with sophisticated gene-engineered mice studies in the past decade enabled a deeper understanding of leptin's action in more detail. Here, we summarize the updated understanding of the action as well as regulation of leptin and point out the emerging direction of research on leptin.

Prolonged fasting times reap greater geroprotective effects when combined with caloric restriction in adult female mice

Emerging new evidence highlights the importance of prolonged daily fasting periods for the health and survival benefits of calorie restriction (CR) and time-restricted feeding (TRF) in male mice; however, little is known about the impact of these feeding regimens in females. We placed 14-month-old female mice on five different dietary regimens, either CR or TRF with different feeding windows, and determined the effects of these regimens on physiological responses, progression of neoplasms and inflammatory diseases, serum metabolite levels, and lifespan. Compared with TRF feeding, CR elicited a robust systemic response, as it relates to energetics and healthspan metrics, a unique serum metabolomics signature in overnight fasted animals, and was associated with an increase in lifespan. These results indicate that daytime (rest-phase) feeding with prolonged fasting periods initiated late in life confer greater benefits when combined with imposed lower energy intake.

Effect of early vs. late time-restricted high-fat feeding on circadian metabolism and weight loss in obese mice

Time-restricted feeding (TRF) limits the time and duration of food availability without calorie reduction. Although a high-fat (HF) diet leads to disrupted circadian rhythms, TRF can prevent metabolic diseases, emphasizing the importance of the timing component. However, the question of when to implement the feeding window and its metabolic effect remains unclear, specifically in obese and metabolically impaired animals. Our aim was to study the effect of early vs. late TRF-HF on diet-induced obese mice in an 8:16 light-dark cycle. C57BL male mice were fed ad libitum a high-fat diet for 14 weeks after which they were given the same food during the early (E-TRF-HF) or late (L-TRF-HF) 8 h of the dark phase for 5 weeks. The control groups were fed ad libitum either a high-fat (AL-HF) or a low-fat diet (AL-LF). Respiratory exchange ratio (RER) was highest for the AL-LF group and the lowest for the AL-HF group. E-TRF-HF led to lower body weight and fat depots, lower glucose, C-peptide, insulin, cholesterol, leptin, TNFα, and ALT levels compared with L-TRF-HF- and AL-HF-fed mice. TRF-HF regardless whether it was early or late led to reduced inflammation and fat accumulation compared with AL-HF-fed mice. E-TRF-HF led to advanced liver circadian rhythms with higher amplitudes and daily expression levels of clock proteins. In addition, TRF-HF led to improved metabolic state in muscle and adipose tissue. In summary, E-TRF-HF leads to increased insulin sensitivity and fat oxidation and decreased body weight, fat profile and inflammation contrary to AL-HF-fed, but comparable to AL-LF-fed mice. These results emphasize the importance of timed feeding compared to ad libitum feeding, specifically to the early hours of the activity period.

Targeting Energy Intake and Circadian Biology to Engage Mechanisms of Aging in Older Adults With Obesity: Calorie Restriction and Time-Restricted Eating

With the rise in obesity across age groups, it has been a hindrance to engaging in physical activity and mobility in older adults. Daily calorie restriction (CR) up to 25% has been the cornerstone of obesity management even though the safety in older adults remains incompletely understood. Although some adults can follow CR with clinically significant weight loss and improved health metrics, CR faces 2 obstacles-many fail to adopt CR and even among those who can adopt it short term, long-term compliance can be difficult. Furthermore, there is a continuing debate about the net benefits of CR-induced weight loss in older adults because of the concern that CR may worsen sarcopenia, osteopenia, and frailty. The science of circadian rhythm and its plasticity toward the timing of nutrition offer promise to alleviate some challenges of CR. The new concept of Time-Restricted Feeding/Eating (TRF for animal studies and TRE for human studies) can be an actionable approach to sustaining the circadian regulation of physiology, metabolism, and behavior. TRE can often (not always) lead to CR. Hence, the combined effect of TRE through circadian optimization and CR can potentially reduce weight and improve cardiometabolic and functional health while lessening the detrimental effects of CR. However, the science and efficacy of TRE as a sustainable lifestyle in humans are in its infancy, whereas animal studies have offered many desirable outcomes and underlying mechanisms. In this article, we will discuss the scope and opportunities to combine CR, exercise, and TRE to improve functional capacity among older adults with obesity.