Metabolomics Insights into the Modulatory Effects of Long-Term Low Calorie Intake in Mice

Independent and combined effects of calorie restriction and AICAR on glucose uptake and insulin signaling in skeletal muscles from 24-month-old female and male rats

We assessed the effects of two levels of calorie restriction (CR; eating either 15% or 35% less than ad libitum, AL, food intake for 8 weeks) by 24-month-old female and male rats on glucose uptake (GU) and phosphorylation of key signaling proteins (Akt; AMP-activated protein kinase, AMPK; Akt substrate of 160 kDa, AS160) measured in isolated skeletal muscles that underwent four incubation conditions (without either insulin or AICAR, an AMPK activator; with AICAR alone; with insulin alone; or with insulin and AICAR). Regardless of sex: (1) neither CR group versus the AL group had greater GU by insulin-stimulated muscles; (2) phosphorylation of Akt in insulin-stimulated muscles was increased in 35% CR versus AL rats; (3) prior AICAR treatment of muscle resulted in greater GU by insulin-stimulated muscles, regardless of diet; and (4) AICAR caused elevated phosphorylation of acetyl CoA carboxylase, an indicator of AMPK activation, in all diet groups. There was a sexually dimorphic diet effect on AS160 phosphorylation, with 35% CR exceeding AL for insulin-stimulated muscles in male rats, but not in female rats. Our working hypothesis is that the lack of a CR-effect on GU by insulin-stimulated muscles was related to the extended duration of the ex vivo incubation period (290 min compared to 40-50 min that was previously reported to be effective). The observed efficacy of prior treatment of muscles with AICAR to improve glucose uptake in insulin-stimulated muscles supports the strategy of targeting AMPK with the goal of improving insulin sensitivity in older females and males.

Microbiota-derived acetate enhances host antiviral response via NLRP3

Pathogenic viral infections represent a major challenge to human health. Host immune responses to respiratory viruses are closely associated with microbiome and metabolism via the gut-lung axis. It has been known that host defense against influenza A virus (IAV) involves activation of the NLRP3 inflammasome, however, mechanisms behind the protective function of NLRP3 are not fully known. Here we show that an isolated bacterial strain, Bifidobacterium pseudolongum NjM1, enriched in the gut microbiota of Nlrp3^-/- mice, protects wild-type but not Nlrp3 deficient mice against IAV infection. This effect depends on the enhanced production of type I interferon (IFN-I) mediated by NjM1-derived acetate. Application of exogenous acetate reproduces the protective effect of NjM1. Mechanistically, NLRP3 bridges GPR43 and MAVS, and promotes the oligomerization and signalling of MAVS; while acetate enhances MAVS aggregation upon GPR43 engagement, leading to elevated IFN-I production. Thus, our data support a model of NLRP3 mediating enhanced induction of IFN-I via acetate-producing bacterium and suggest that the acetate-GPR43-NLRP3-MAVS-IFN-I signalling axis is a potential therapeutic target against respiratory viral infections.

Fostering next-generation probiotics in human gut by targeted dietary modulation: An emerging perspective

Emerging evidence and an in-depth understanding of the microbiome have helped in identifying beneficial commensals and their therapeutic potentials. Specific commensal taxa/ strains of the human gut microbiome have been positively associated with human health and recently termed as next-generation probiotics (NGPs). Of these, Akkermansia muciniphila, Ruminococcus bromii, Faecalibacterium prausnitzii, Anaerobutyricum hallii, and Roseburia intestinalis are the five most relevant gut-derived NGPs that have demonstrated therapeutic potential in managing metabolic diseases. Specific and natural dietary interventions can modulate the abundance and activity of these beneficial bacteria in the gut. Hence, the understanding of targeted stimulation of specific NGP by specific probiotic-targeted diets (PTD) is indispensable for the rational application of their combination. The supplementation of NGP with its specific PTD will help the strain(s) to compete with harmful microbes and acquire its niche. This combination would enhance the effectiveness of NGPs to be used as "live biotherapeutic products" or food nutraceuticals. Under the current milieu, we review various PTDs that influence the abundance of specific potential NGPs, and contemplates potential interactions between diet, microbes, and their effects on host health. Taking into account the study mentioned, we propose that combining NGPs will provide an alternate solution for developing the new diet in conjunction with PTD.

New Perspectives on Avian Models for Studies of Basic Aging Processes

Avian models have the potential to elucidate basic cellular and molecular mechanisms underlying the slow aging rates and exceptional longevity typical of this group of vertebrates. To date, most studies of avian aging have focused on relatively few of the phenomena now thought to be intrinsic to the aging process, but primarily on responses to oxidative stress and telomere dynamics. But a variety of whole-animal and cell-based approaches to avian aging and stress resistance have been developed-especially the use of primary cell lines and isolated erythrocytes-which permit other processes to be investigated. In this review, we highlight newer studies using these approaches. We also discuss recent research on age-related changes in neural function in birds in the context of sensory changes relevant to homing and navigation, as well as the maintenance of song. More recently, with the advent of "-omic" methodologies, including whole-genome studies, new approaches have gained momentum for investigating the mechanistic basis of aging in birds. Overall, current research suggests that birds exhibit an enhanced resistance to the detrimental effects of oxidative damage and maintain higher than expected levels of cellular function as they age. There is also evidence that genetic signatures associated with cellular defenses, as well as metabolic and immune function, are enhanced in birds but data are still lacking relative to that available from more conventional model organisms. We are optimistic that continued development of avian models in geroscience, especially under controlled laboratory conditions, will provide novel insights into the exceptional longevity of this animal taxon.

Effect on gut microbiota of a 1-y lifestyle intervention with Mediterranean diet compared with energy-reduced Mediterranean diet and physical activity promotion: PREDIMED-Plus Study

BACKGROUND

The Mediterranean diet is a well-recognized healthy diet that has shown to induce positive changes in gut microbiota. Lifestyle changes such as diet along with physical activity could aid in weight loss and improve cardiovascular risk factors.

OBJECTIVES

To investigate the effect of an intensive lifestyle weight loss intervention on gut microbiota.

METHODS

This is a substudy of the PREDIMED-Plus (Prevención con Dieta Mediterránea-Plus), a randomized controlled trial conducted in overweight/obese men and women (aged 55-75 y) with metabolic syndrome. The intervention group (IG) underwent an intensive weight loss lifestyle intervention based on an energy-restricted Mediterranean diet (MedDiet) and physical activity promotion, and the control group (CG) underwent a non-energy-restricted MedDiet for 1 y. Anthropometric, biochemical, and gut microbial 16S rRNA sequencing data were analyzed at baseline (n = 362) and 1-y follow-up (n = 343).

RESULTS

IG participants had a weight loss of 4.2 (IQR, -6.8, -2.5) kg compared with 0.2 (IQR, -2.1, 1.4) kg in the CG (P < 0.001). Reductions in BMI, fasting glucose, glycated hemoglobin, and triglycerides and an increase in HDL cholesterol were greater in IG than in CG participants (P < 0.05). We observed a decrease in Butyricicoccus, Haemophilus, Ruminiclostridium 5, and Eubacterium hallii in the IG compared with the CG. Many genera shifted in the same direction within both intervention groups, indicating an overall effect of the MedDiet. Decreases in Haemophilus, Coprococcus 3, and few other genera were associated with a decrease in adiposity parameters in both intervention groups. Changes in Lachnospiraceae NK4A136 were positively associated with changes in MedDiet adherence.

CONCLUSIONS

Weight loss induced by an energy-restricted MedDiet and physical activity induce changes in gut microbiota. The role of MedDiet-induced changes on the host might be via short-chain fatty acid producing bacteria, whereas with energy restriction, these changes might be modulated with other mechanisms, which need to be explored in future studies. This trial was registered at http://www.isrctn.com/ISRCTN89898870 as ISRCT 89898870.

Combined signature of rumen microbiome and metabolome in dairy cows with different feed intake levels

Feed intake is a major factor in maintaining the balance between ruminal fermentation and the microbial community of dairy cows. To explore the relationship among feed intake, microbial metabolism, and ruminal fermentation, we examined the combined signatures of the microbiome and metabolome in dairy cows with different feed intake levels. Eighteen dairy cows were allocated to high feed intake (HFI), medium feed intake (MFI), and low feed intake (LFI) groups according to their average daily feed intake. 16S rDNA sequencing results revealed that the relative abundance of Firmicutes in the HFI group was significantly higher than that in the MFI and LFI groups (P < 0.05). The ratio of Bacteroidetes to Firmicutes was significantly lower in the HFI group than in the MFI and LFI groups (P < 0.05). The relative abundance of Lachnospiraceae_unclassified, Veillonellaceae_unclassified, and Saccharofermentants was significantly higher in the HFI group than in the LFI and MFI groups (P < 0.05). The relative abundance of Erysipelotrichaceae_unclassified and Butyrivibrio was significantly higher in the HFI group than in the MFI and LFI groups (P < 0.05). Ultra high performance liquid chromatography-mass spectrometry revealed five key pathways, including the linoleic acid metabolism pathway, alpha-linolenic acid metabolism, arginine and proline metabolism, glutathione metabolism, and valine, leucine, and isoleucine biosynthesis, which are closely related to energy and amino acid metabolism. Linoleic acid, glutamate, alpha-linolenic acid, l-methionine, and l-valine levels were significantly lower in the HFI group than in the MFI and LFI groups (q < 0.05), while the relative content of glutamate was significantly lower in the MFI group than in the LFI group (q < 0.05). Stearic acid content was significantly higher in the HFI group than in the LFI group (q < 0.05). Our findings provide insight into the rumen microbiome of dairy cows with different feed intake and the metabolic pathways closely associated with feed intake in early-lactating cows. The candidates involved in these metabolic pathways may be useful for identifying variations in feed intake. The signatures of the rumen microbiome and metabolome in dairy cows may help make decisions regarding feeding.

Comparative Blood and Urine Metabolomics Analysis of Healthy Elderly and Young Male Singaporeans

Comparative metabolomics analysis of biofluids could provide information about the metabolic alterations in aging. To investigate the signature of multiple metabolic profiles associated with aging in an Asian population, we performed a pilot study in healthy Singaporeans, including 33 elderly and 33 young males. Fasting whole bloods were analyzed by routine hematology; the serum and urine metabolome profiles were obtained using NMR-based nontargeted metabolomics analysis and targeted lipoprotein analysis. Among the 90 identified compounds in serum and urine samples, 32 were significantly different between the two groups. The most obvious age-related metabolic signatures include decreased serum levels of albumin lysyl and essential amino acids and derivatives but increased levels of N-acetyl glycoproteins and several lipids and elevated urine levels of trimethylamine N-oxide, scyllo-inositol, citrate, and ascorbic acid but decreased levels of several amino acids, acetate, etc. Among 112 lipoprotein subfractions, 65 were elevated, and 2 were lower in the elderly group. These significantly age-varying metabolites, especially in the amino acid and fatty acid metabolism pathways, suggest that the regulation of these pathways contributes to the aging process in Chinese Singaporeans. Further multiomics studies including the gut microbiome and intervention studies in a larger cohort are needed to elucidate the possible mechanisms in the aging process.

Transcriptomics and metabonomics of the anti-aging properties of total flavones of Epimedium in relation to lipid metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Total flavones of Epimedium (TFE) is the main active ingredient in Herba Epimedii, which is a well-known Chinese herbal medicine that is widely used to treat certain age-related diseases in oriental countries.

AIM OF THE STUDY

The aim of this work was to investigate the anti-aging properties of TFE related to lipid metabolism.

MATERIALS AND METHODS

Both transcriptomics and metabonomics were applied in this work to investigate the anti-aging properties of TFE. Microarray and LC-MS analysis were conducted on liver samples of three groups of rats, including young (4 months), old (24 months), and old rats administrated TFE.

RESULTS

Transcriptomics analysis highlighted 287 transcripts related to the anti-aging effect of TFE, in which the expression ratio of 18 genes regulating lipid metabolism, including HMGCS1 and NR1H3, returned to normal levels after TFE treatment. In addition, 24 aging-related metabolites were discovered in a metabonomics study, and 15 of these were structurally identified, including palmitic amide, linoleamide, and oleamide. Bioinformatics and integral data analysis on the results of the transcriptomics and metabonomics suggest the involvement of 12 key metabolic pathways, half of which are highly related to lipid metabolism.

CONCLUSIONS

This study demonstrates that the role played by TFE in the lipid metabolism of aging rats is multifaceted and multi-layered.

You are what you eat: diet, health and the gut microbiota

Since the renaissance of microbiome research in the past decade, much insight has accumulated in comprehending forces shaping the architecture and functionality of resident microorganisms in the human gut. Of the multiple host-endogenous and host-exogenous factors involved, diet emerges as a pivotal determinant of gut microbiota community structure and function. By introducing dietary signals into the nexus between the host and its microbiota, nutrition sustains homeostasis or contributes to disease susceptibility. Herein, we summarize major concepts related to the effect of dietary constituents on the gut microbiota, highlighting chief principles in the diet-microbiota crosstalk. We then discuss the health benefits and detrimental consequences that the interactions between dietary and microbial factors elicit in the host. Finally, we present the promises and challenges that arise when seeking to incorporate microbiome data in dietary planning and portray the anticipated revolution that the field of nutrition is facing upon adopting these novel concepts.

Calorie restriction and its impact on gut microbial composition and global metabolism

Calorie restriction (CR) is a dietary regimen that reduces calorie intake without incurring malnutrition or a reduction in essential nutrients. It has long been recognized as a natural strategy for promoting health, extending longevity, and prevents the development of metabolic and age-related diseases. In the present review, we focus on the general effect of CR on gut microbiota composition and global metabolism. We also propose mechanisms for its beneficial effect. Results showed that probiotic and butyrate-producing microbes increased their relative abundance, whereas proinflammatory strains exhibited suppressed relative abundance following CR. Analyses of the gut microbial and host metabolisms revealed that most host microbial co-metabolites were changed due to CR. Examples of dramatic CR-induced changes in host metabolism included a decrease in the rate of lipid biosynthesis and an increase in the rates of fatty acid catabolism, β-oxidation, glycogenolysis, and gluconeogenesis. The observed phenotypes and the further verification of the direct link between gut microbiota and metabolome may benefit patients that are at risk for developing metabolic disease. Thus, improved gut microbiota composition and metabolome are potential biomarkers for determining the effectiveness of dietary interventions for age-related and metabolic diseases.

Caloric restriction promotes functional changes involving short-chain fatty acid biosynthesis in the rat gut microbiota

Caloric restriction (CR) is known to promote health and longevity, likely via modification of the gut microbiota (GM). However, functional and metabolic changes induced in the GM during CR are still unidentified. Here, we investigated the short- and long-term effects of CR on the rat GM using a metaproteogenomic approach. We show that a switch from ad libitum (AL) low fat diet to CR in young rats is able to induce rapid and deep changes in their GM metaproteomic profile, related to a reduction of the Firmicutes/Bacteroidetes ratio and an expansion of lactobacilli. Specifically, we observed a significant change in the expression of the microbial enzymes responsible for short-chain fatty acid biosynthesis, with CR boosting propionogenesis and limiting butyrogenesis and acetogenesis. Furthermore, these CR-induced effects were maintained up to adulthood and started to be reversed after a short-term diet change. We also found that CR alters the abundance of an array of host proteins released in stool, mainly related to epithelial barrier integrity and inflammation. Hence, our results provide thorough information about CR-induced modifications to GM and host functional activity, and might constitute the basis for novel GM-based approaches aimed at monitoring the effectiveness of dietary interventions.

Predominant gut Lactobacillus murinus strain mediates anti-inflammaging effects in calorie-restricted mice

BACKGROUND

Calorie restriction (CR), which has a potent anti-inflammaging effect, has been demonstrated to induce dramatic changes in the gut microbiota. Whether the modulated gut microbiota contributes to the attenuation of inflammation during CR is unknown, as are the members of the microbial community that may be key mediators of this process.

RESULTS

Here, we report that a unique Lactobacillus-predominated microbial community was rapidly attained in mice within 2 weeks of CR, which decreased the levels of circulating microbial antigens and systemic inflammatory markers such as tumour necrosis factor alpha (TNF-α). Lactobacillus murinus CR147, an isolate in the most abundant operational taxonomic unit (OTU) enriched by CR, downregulated interleukin-8 production in TNF-α-stimulated Caco-2 cells and significantly increased the lifespan and the brood size of the nematode Caenorhabditis elegans. In gnotobiotic mice colonized with the gut microbiota from old mice, this strain decreased their intestinal permeability and serum endotoxin load, consequently attenuating the inflammation induced by the old microbiota.

CONCLUSIONS

Our study demonstrated that a strain of Lactobacillus murinus was promoted in CR mice and causatively contributed to the attenuation of ageing-associated inflammation.

Exploring the Impact of Food on the Gut Ecosystem Based on the Combination of Machine Learning and Network Visualization

Prebiotics and probiotics strongly impact the gut ecosystem by changing the composition and/or metabolism of the microbiota to improve the health of the host. However, the composition of the microbiota constantly changes due to the intake of daily diet. This shift in the microbiota composition has a considerable impact; however, non-pre/probiotic foods that have a low impact are ignored because of the lack of a highly sensitive evaluation method. We performed comprehensive acquisition of data using existing measurements (nuclear magnetic resonance, next-generation DNA sequencing, and inductively coupled plasma-optical emission spectroscopy) and analyses based on a combination of machine learning and network visualization, which extracted important factors by the Random Forest approach, and applied these factors to a network module. We used two pteridophytes, Pteridium aquilinum and Matteuccia struthiopteris, for the representative daily diet. This novel analytical method could detect the impact of a small but significant shift associated with Matteuccia struthiopteris but not Pteridium aquilinum intake, using the functional network module. In this study, we proposed a novel method that is useful to explore a new valuable food to improve the health of the host as pre/probiotics.