Lifelong calorie restriction and markers of colonic health in aging mice
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ABSTRACT: Diminishment of colonic health is associated with various age-related pathologies. Calorie restriction (CR) is an efficient strategy to increase healthy lifespan, although underlying mechanisms are not fully elucidated. Here we report the effects of lifelong CR on markers of colonic health in aging mice. We show that 30% energy reduction, as compared to a control (C) and moderate-fat (MF) diet, is associated with attenuated immune-related gene expression and lower levels of bile acids in the colon. Pronounced shifts in microbiota composition, together with lowered plasma levels of interleukin 6, in mice exposed to CR are in line with these findings. Furthermore, expression of genes involved in lipid metabolism was higher upon CR as compared to C and MF, pointing towards efficient regulation of energy metabolism. Switching from CR to an ad libitum MF diet at old age revealed remarkable phenotypic plasticity, although expression of a small subset of genes remained CR-associated. This research demonstrates that CR beneficially affects markers of colonic health in aging mice and as such may attenuate the progressive age-related decline in health.
Project description:Calorie restriction (CR) has been shown to extend life- and health-span in model species. For most humans, a life-long CR diet is too arduous to adhere to. The aim of this study was to explore whether weekly intermittent CR can 1) provide long-term beneficial effects and 2) counteract diet-induced obesity in male aging mice. In this study, we have exposed C57Bl/6J mice for 24 months to an intermittent (INT) diet, alternating weekly between CR of a control diet and ad libitum moderate-fat (MF) feeding. This weekly intermittent CR significantly counteracted the adverse effects of the MF diet on mortality, body weight and liver health markers in male 24-month-old mice. Hepatic gene expression profiles of INT-exposed animals appeared much more comparable to CR than to MF-exposed mice. At 12 months of age, a subgroup of MF-exposed mice was transferred to the INT diet. Gene expression profiles in the liver of the 24-month-old diet switch mice were highly similar to the INT-exposed mice. However, a small subset of genes was consistently changed by the MF diet during the first phase of life. Weekly intermittent CR largely, but not completely, reversed adverse effects caused by a MF diet.
Project description:Calorie restriction (CR) is a dietary regimen that supports healthy aging. In this study we investigated the systemic and liver-specific responses caused by a diet switch to a medium-fat (MF) diet in 24-month-old life-long, CR-exposed mice. This study aimed to increase the knowledge base on dietary alterations of gerontological relevance. Nine-week-old C57BL/6J mice were exposed either to a control, CR or MF diet. At the age of 24 months, a subset of mice of the CR group was transferred to ad libitum MF feeding (CR-MF).The mice were sacrificed at the age of 28 months, then biochemical and molecular analyses were performed. Our results showed that, despite the long-term exposure to the CR regimen, mice in the CR-MF group displayed hyperphagia, rapid weight gain, and hepatic steatosis. However, no hepatic fibrosis/injury or alteration in CR-improved survival was observed in the diet switch group. The liver transcriptomic profile of CR-MF mice largely shifted to a profile similar to the MF-fed animals but leaving ~22% of the 1578 differentially regulated genes between the CR and MF diet groups comparable with the expression of the life-long CR group. Therefore, although the diet switch was performed at an old age, the CR-MF-exposed mice showed plasticity in coping with the challenge of a MF diet without developing severe liver pathologies.
Project description:SCOPE: We investigated whether a novel dietary intervention consisting of an every-other-week calorie-restricted diet could prevent nonalcoholic fatty liver disease (NAFLD) development induced by a medium-fat (MF) diet. METHODS AND RESULTS: Nine-week-old male C57BL/6J mice received either a (i) control (C), (ii) 30E% calorie restricted (CR), (iii) MF (25E% fat), or (iv) intermittent (INT) diet, a diet alternating weekly between 40E% CR and an ad libitum MF diet until sacrifice at the age of 12 months. The metabolic, morphological, and molecular features of NAFLD were examined. The INT diet resulted in healthy metabolic and morphological features as displayed by the continuous CR diet: glucose tolerant, low hepatic triglyceride content, low plasma alanine aminotransferase. In contrast, the C- and MF-exposed mice with high body weight developed signs of NAFLD. However, the gene expression profiles of INT-exposed mice differed to those of CR-exposed mice and showed to be more similar with those of C- and MF-exposed mice with a comparable body weight. CONCLUSIONS: Our study reveals that the INT diet maintains metabolic health and reverses the adverse effects of the MF diet, thus effectively prevents the development of NAFLD in 12-month-old male C57BL/6J mice. Male C57Bl/6J mice were divided to 4 dietary intervention groups: Control (AIN-93W), 30% calorie restriction (CR; AIN-93W-CR), medium fat (MF; AIN-93W-MF; 25% energy from fat) and intermittent diet (INT; weekly alternating diet between AIN-93W-MF ad lib and 40% CR of AIN-93W). We performed various measurements on metabolic parameters and gene expression analysis on the liver. This entry represents the microarray data of the liver gene expression of each mouse.
Project description:Diminished colonic health is associated with various age-related pathologies. In this study, we applied an integrative approach to reveal potential interactions between determinants of colonic health in aging C57BL/6J mice. Analysis of gut microbiota composition revealed an enrichment of various potential pathobionts, including Desulfovibrio spp., and a decline of the health-promoting Akkermansia spp. and Lactobacillus spp. during aging. Intraluminal concentrations of various metabolites varied between ages and we found evidence for an increased gut permeability at higher age. Colonic gene expression analysis suggested that during the early phase of aging (between 6 and 12 months), expression of genes involved in epithelial-to-mesenchymal transition and (re)organization of the extracellular matrix were increased. Differential expression of these genes was strongly correlated with Bifidobacterium spp. During the later phase of aging (between 12 and 28 months), gene expression profiles pointed towards a diminished antimicrobial defense and were correlated with an uncultured Gastranaerophilales spp. This study demonstrates that aging is associated with pronounced changes in gut microbiota composition and colonic gene expression. Furthermore, the strong correlations between specific bacterial genera and host gene expression may imply that orchestrated interactions take place in the vicinity of the colonic wall and potentially mediate colonic health during aging.
Project description:Calorie restriction (CR) is the most robust non-genetic intervention to universally delay the onset of age-related diseases and extend mean and maximum lifespan. However, species, strain, sex, diet, age of onset, and level of CR are emerging as important variables to consider for a successful CR response. Here, we investigated the role of strain, sex and level of CR on outcomes of health and survival in mice. Response to CR varied from lifespan extension to no effect on survival, while consistently delaying the onset and impact of diseases independently of strain, sex and level of dietary restriction. CR led to transcriptional and metabolomics changes in the liver indicating anaplerotic filling of the Krebs cycle together with fatty acid fueling of mitochondria. Additionally, CR prevented the age-associated decline in the proteostasis network. Further, CR increased mitochondrial number and preserved their ultrastructure and function with age. Abrogation of mitochondrial function by deletion of fumarate hydratase or malate dehydrogenase 2 negated the life-prolonging effects of CR in yeast and worms. In F1 hybrid strains of mice, the lifespan response to CR tracked with the dam, indicating that the mitochondrial haplotype is an important regulator of CR. Our data illustrate the complexity of the CR responses within a single animal species in the context of aging, with a clear separation of outcomes related to health and survival, highlighting the complexities of translation of CR into human interventions. The study examines the effects of sex (male/female), mouse strain (DBA2/J versus C57BL/J), and diet (Ad libitum, 20% caloric restriction (20%CR), or 40%CR) using six biological replicate samples per group.
Project description:As global life expectancy continues to climb, maintaining skeletal muscle function is increasingly essential to ensure a good life quality for aging populations. Calorie restriction (CR) is the most potent and reproducible intervention to extend health and lifespan, but is largely unachievable in humans. Therefore, identification of “CR mimetics” has received much attention. Since CR targets nutrient-sensing pathways centering on mTORC1, rapamycin, the allosteric inhibitor of mTORC1, has been proposed as a potential CR mimetic and counteracts age-related muscle loss. Therefore, we tested whether rapamycin acts via similar mechanisms as CR to slow muscle aging. Contrary to our prediction, long-term CR and rapamycin-treated geriatric mice display distinct skeletal muscle gene expression profiles despite both conferring benefits to aging skeletal muscle. Furthermore, CR improved muscle integrity in a mouse with nutrient-insensitive sustained muscle mTORC1 activity and rapamycin provided additive benefits to CR in aging mouse muscles. Therefore, RM and CR exert distinct, compounding effects in aging skeletal muscle, opening the possibility of parallel interventions to counteract muscle aging.
Project description:Fibroblast growth factor 21 (Fgf21) has emerged as a potential plasma marker to diagnose non-alcoholic fatty liver disease (NAFLD). To study the molecular processes underlying the association of plasma Fgf21 with NAFLD, we explored the liver transcriptome data of a mild NAFLD model of aging C57BL/6J mice at 12, 24, and 28 months of age. The plasma Fgf21 level significantly correlated with intrahepatic triglyceride content. At the molecular level, elevated plasma Fgf21 levels were associated with dysregulated metabolic and cancer-related pathways. The up-regulated Fgf21 levels in NAFLD were implied to be a protective response against the NAFLD-induced adverse effects, e.g. lipotoxicity, oxidative stress and endoplasmic reticulum stress. An in vivo PPARalpha challenge demonstrated the dysregulation of PPARalpha signalling in the presence of NAFLD, which resulted in a stochastically increasing hepatic expression of Fgf21. Notably, elevated plasma Fgf21 was associated with declining expression of Klb, Fgf21â??s crucial co-receptor, which suggests a resistance to Fgf21. Therefore, although liver fat accumulation is a benign stage of NAFLD, the elevated plasma Fgf21 likely indicated vulnerability to metabolic stressors that may contribute towards progression to end-stage NAFLD. In conclusion, plasma levels of Fgf21 reflect liver fat accumulation and dysregulation of metabolic pathways in the liver. Male C57Bl/6J mice were divided to 3 dietary intervention groups: Control (AIN-93W), 30% calorie restriction (CR; AIN-93W-CR) and medium fat (MF; AIN-93W-MF; 25% energy from fat). Dietary interventions started at the age of 9 weeks and sacrifice was performed at the age of 6, 12, 24 and 28 months. We performed various measurements on metabolic parameters and gene expression analysis. This entry represents the microarray data.
Project description:SCOPE: We investigated whether a novel dietary intervention consisting of an every-other-week calorie-restricted diet could prevent nonalcoholic fatty liver disease (NAFLD) development induced by a medium-fat (MF) diet. METHODS AND RESULTS: Nine-week-old male C57BL/6J mice received either a (i) control (C), (ii) 30E% calorie restricted (CR), (iii) MF (25E% fat), or (iv) intermittent (INT) diet, a diet alternating weekly between 40E% CR and an ad libitum MF diet until sacrifice at the age of 12 months. The metabolic, morphological, and molecular features of NAFLD were examined. The INT diet resulted in healthy metabolic and morphological features as displayed by the continuous CR diet: glucose tolerant, low hepatic triglyceride content, low plasma alanine aminotransferase. In contrast, the C- and MF-exposed mice with high body weight developed signs of NAFLD. However, the gene expression profiles of INT-exposed mice differed to those of CR-exposed mice and showed to be more similar with those of C- and MF-exposed mice with a comparable body weight. CONCLUSIONS: Our study reveals that the INT diet maintains metabolic health and reverses the adverse effects of the MF diet, thus effectively prevents the development of NAFLD in 12-month-old male C57BL/6J mice.
Project description:Calorie restriction (CR) is the most robust non-genetic intervention to universally delay the onset of age-related diseases and extend mean and maximum lifespan. However, species, strain, sex, diet, age of onset, and level of CR are emerging as important variables to consider for a successful CR response. Here, we investigated the role of strain, sex and level of CR on outcomes of health and survival in mice. Response to CR varied from lifespan extension to no effect on survival, while consistently delaying the onset and impact of diseases independently of strain, sex and level of dietary restriction. CR led to transcriptional and metabolomics changes in the liver indicating anaplerotic filling of the Krebs cycle together with fatty acid fueling of mitochondria. Additionally, CR prevented the age-associated decline in the proteostasis network. Further, CR increased mitochondrial number and preserved their ultrastructure and function with age. Abrogation of mitochondrial function by deletion of fumarate hydratase or malate dehydrogenase 2 negated the life-prolonging effects of CR in yeast and worms. In F1 hybrid strains of mice, the lifespan response to CR tracked with the dam, indicating that the mitochondrial haplotype is an important regulator of CR. Our data illustrate the complexity of the CR responses within a single animal species in the context of aging, with a clear separation of outcomes related to health and survival, highlighting the complexities of translation of CR into human interventions.
Project description:Caloric restriction (CR) improves survival in nonhuman primates and delays the onset of age-related morbidities including sarcopenia, the age-related loss of muscle mass and function. A shift in metabolism anticipates the onset of muscle aging phenotypes in nonhuman primates suggesting a potential role for metabolism in CR’s protective effects. Here we show that CR induced profound changes in muscle composition and the cellular metabolic environment. Bioinformatic analysis linked these adaptations to proteostasis, RNA processing, and lipid synthetic pathways. At the tissue level, CR maintained contractile content and attenuated age-related metabolic shifts among individual fiber types with higher mitochondrial activity, altered redox metabolism, and smaller lipid droplet size. Biometric and metabolic rate data confirm preserved metabolic efficiency in CR animals that correlated with attenuation of age-related muscle mass and physical activity. These data suggest that CR-induced reprogramming of metabolism plays a role in delayed aging of skeletal muscle in rhesus monkeys.