Functional Gut Microbiota Remodeling Contributes to the Caloric Restriction-Induced Metabolic Improvements

Cross-talk between adipose tissue and microbiota-gut-brain-axis in brain development and neurological disorder

The gut microbiota is an important factor responsible for the physiological processes as well as pathogenesis of host. The communication between central nervous system (CNS) and microbiota occurs by different pathways i.e., chemical, neural, immune, and endocrine. Alteration in gut microbiota i.e., gut dysbiosis causes alteration in the bidirectional communication between CNS and gut microbiota and linked to the pathogenesis of neurological and neurodevelopmental disorder. Therefore, now-a-days microbiota-gut-brain-axis (MGBA) has emerged as therapeutic target for the treatment of metabolic disorder. But, experimental data available on MGBA from basic research has limited application in clinical study. In present study we first summarized molecular mechanism of microbiota interaction with brain physiology and pathogenesis via collecting data from different sources i.e., PubMed, Scopus, Web of Science. Furthermore, evidence shows that adipose tissue (AT) is active during metabolic activities and may also interact with MGBA. Hence, in present study we have focused on the relationship among MGBA, brown adipose tissue, and white adipose tissue. Along with this, we have also studied functional specificity of AT, and understanding heterogeneity among MGBA and different types of AT. Therefore, molecular interaction among them may provide therapeutic target for the treatment of neurological disorder.

Effects of Different Exercises Combined with Different Dietary Interventions on Body Composition: A Systematic Review and Network Meta-Analysis

BACKGROUND

Exercise and dietary interventions are essential for maintaining weight and reducing fat accumulation. With the growing popularity of various dietary strategies, evidence suggests that combining exercise with dietary interventions offers greater benefits than either approach alone. Consequently, this combined strategy has become a preferred method for many individuals aiming to maintain health. Calorie restriction, 5/2 intermittent fasting, time-restricted feeding, and the ketogenic diet are among the most popular dietary interventions today. Aerobic exercise, resistance training, and mixed exercise are the most widely practiced forms of physical activity. Exploring the best combinations of these approaches to determine which yields the most effective results is both meaningful and valuable. Despite this trend, a comparative analysis of the effects of different exercise and diet combinations is lacking. This study uses network meta-analysis to evaluate the impact of various combined interventions on body composition and to compare their efficacy.

METHODS

We systematically reviewed literature from database inception through May 2024, searching PubMed, Web of Science, Embase, and the Cochrane Library. The study was registered in PROSPERO under the title: "Effects of Exercise Combined with Different Dietary Interventions on Body Composition: A Systematic Review and Network Meta-Analysis" (identifier: CRD42024542184). Studies were meticulously selected based on specific inclusion and exclusion criteria (The included studies must be randomized controlled trials involving healthy adults aged 18 to 65 years. Articles were rigorously screened according to the specified inclusion and exclusion criteria.), and their risk of bias was assessed using the Cochrane risk of bias tool. Data were aggregated and analyzed using network meta-analysis, with intervention efficacy ranked by Surface Under the Cumulative Ranking (SUCRA) curves.

RESULTS

The network meta-analysis included 78 randomized controlled trials with 5219 participants, comparing the effects of four combined interventions: exercise with calorie restriction (CR+EX), exercise with time-restricted eating (TRF+EX), exercise with 5/2 intermittent fasting (5/2F+EX), and exercise with a ketogenic diet (KD+EX) on body composition. Intervention efficacy ranking was as follows: (1) Weight Reduction: CR+EX > KD+EX > TRF+EX > 5/2F+EX (Relative to CR+EX, the effect sizes of 5/2F+EX, TRF+EX and KD+EX are 2.94 (-3.64, 9.52); 2.37 (-0.40, 5.15); 1.80 (-1.75, 5.34)). (2) BMI: CR+EX > KD+EX > 5/2F+EX > TRF+EX (Relative to CR+EX, the effect sizes of 5/2F+EX, TRF+EX and KD+EX are 1.95 (-0.49, 4.39); 2.20 (1.08, 3.32); 1.23 (-0.26, 2.71)). (3) Body Fat Percentage: CR+EX > 5/2F+EX > TRF+EX > KD+EX (Relative to CR+EX, the effect sizes of 5/2F+EX, TRF+EX and KD+EX are 2.66 (-1.56, 6.89); 2.84 (0.56, 5.13); 3.14 (0.52, 5.75).). (4) Lean Body Mass in Male: CR+EX > TRF+EX > KD+EX (Relative to CR+EX, the effect sizes of TRF+EX and KD+EX are -1.60 (-6.98, 3.78); -2.76 (-7.93, 2.40)). (5) Lean Body Mass in Female: TRF+EX > CR+EX > 5/2F+EX > KD+EX (Relative to TRF+EX, the effect sizes of CR+EX, 5/2F+EX and KD+EX are -0.52 (-2.58, 1.55); -1.83 (-4.71, 1.04); -2.46 (-5.69,0.76).).

CONCLUSION

Calorie restriction combined with exercise emerged as the most effective strategy for reducing weight and fat percentage while maintaining lean body mass. For women, combining exercise with time-restricted eating proved optimal for preserving muscle mass. While combining exercise with a ketogenic diet effectively reduces weight, it is comparatively less effective at decreasing fat percentage and preserving lean body mass. Hence, the ketogenic diet combined with exercise is considered suboptimal.

Effects of calorie-restricted diet on health state and intestinal flora in Hashimoto's thyroiditis patients: Study protocol for a randomized controlled trial

BACKGROUND AND OBJECTIVES

Hashimoto's thyroiditis (HT) is an autoimmune disease, characterized by abnormal elevation in thyroid peroxidase antibody and/or thyroglobulin antibody. In recent decades, HT disease has become more and more widespread. Patients always report multiple symptoms, even though their thyroid hormone levels are kept in normal ranges. However, no treatment exists to effectively reduce the levels of thyroid antibodies. Our study aims to determine whether calorie-restricted diet is helpful in improving health of HT patients.

METHODS AND STUDY DESIGN

This is a 3-month randomized controlled trial. HT patients will be randomized into a calorie-restricted (CR) group or a calorie-unrestricted control group. All the participants will be instructed to consume a diet that includes a combination of 45-55% calories from carbohydrates, 20-30% from fats, and 15-25% from proteins, according to current Chinese Dietary Guidelines. Participants in CR group need to limit their calories intake equal to their basal energy expenditure, which means that their daily caloric intake will be limited by about 20-30%.

RESULTS

The study population is planned to be 66 HT patients aged 18 to 65 years. The primary outcome is change of thyroid antibody levels from baseline. Secondary outcomes include the changes of non-hypothyroid symptoms scores, thyroid function indexes, morphology of thyroid, T lymphocyte subpopulations, inflammatory biomarkers and lipids from baseline to 12 weeks.

CONCLUSIONS

This trial will have implications for nutrition treatment policy in regard to thyroid antibodies control, immune dysfunction and related non-hypothyroid symptoms improvement among HT patients.

The Effects of Caloric Restriction and Clinical Psychological Intervention on the Interplay of Gut Microbial Composition and Stress in Women

Both mental and metabolic disorders are steadily becoming more prevalent, increasing interest in non-pharmacological lifestyle interventions targeting both types of disorders. However, the combined effect of diet and psychological interventions on the gut microbiome and mental health outcomes remains underexplored. Thus, in this study, we randomized 41 women into two caloric restriction (CR) dietary groups, namely very-low-calorie diet (VLCD) and F.X. Mayr diet (FXM). The patients were then further randomized to either receive clinical psychological intervention (CPI) or no CPI. Blood and fecal samples were collected before and after two weeks of CR. Psychometric outcomes were assessed using the Perceived Stress Scale (PSS), Brief Symptom Index (BSI), and Burnout Dimension Inventory (BODI). Stool samples underwent 16S-rRNA sequencing. Upon two weeks of CR, α-diversity decreased overall and longitudinal PERMANOVA models revealed significant shifts in β-diversity according to diet, CPI, age, and body-mass-index. Furthermore, Agathobacter, Fusicatenibacter, and Subdoligranulum decreased in abundance. However, the Oscillibacter genus was enriched solely in FXM. CPI had a negligible effect on the microbiome. Dimension reduction models revealed clusters of taxa which distinctly associated with psychometric outcomes. Members of the Oscillospiraceae family were linked to favorable psychometric outcomes after two weeks of CR. Despite α-diversity reductions after CR, enrichment of Oscillospiraceae spp., solely seen in FXM, correlated with improved psychometric outcomes. This study suggests a promising direction for future interventions targeting mental health through gut microbial modulation.

Intermittent fasting, calorie restriction, and a ketogenic diet improve mitochondrial function by reducing lipopolysaccharide signaling in monocytes during obesity: A randomized clinical trial

BACKGROUND

Mitochondrial dysfunction occurs in monocytes during obesity and contributes to a low-grade inflammatory state; therefore, maintaining good mitochondrial conditions is a key aspect of maintaining health. Dietary interventions are primary strategies for treating obesity, but little is known about their impact on monocyte bioenergetics. Thus, the aim of this study was to evaluate the effects of calorie restriction (CR), intermittent fasting (IF), a ketogenic diet (KD), and an ad libitum habitual diet (AL) on mitochondrial function in monocytes and its modulation by the gut microbiota.

METHODS AND FINDINGS

A randomized controlled clinical trial was conducted in which individuals with obesity were assigned to one of the 4 groups for 1 month. Subsequently, the subjects received rifaximin and continued with the assigned diet for another month. The oxygen consumption rate (OCR) was evaluated in isolated monocytes, as was the gut microbiota composition in feces and anthropometric and biochemical parameters. Forty-four subjects completed the study, and those who underwent CR, IF and KD interventions had an increase in the maximal respiration OCR (p = 0.025, n2p = 0.159 [0.05, 0.27] 95% confidence interval) in monocytes compared to that in the AL group. The improvement in mitochondrial function was associated with a decrease in monocyte dependence on glycolysis after the IF and KD interventions. Together, diet and rifaximin increased the gut microbiota diversity in the IF and KD groups (p = 0.0001), enriched the abundance of Phascolarctobacterium faecium (p = 0.019) in the CR group and Ruminococcus bromii (p = 0.020) in the CR and KD groups, and reduced the abundance of lipopolysaccharide (LPS)-producing bacteria after CR, IF and KD interventions compared to the AL group at the end of the study according to ANCOVA with covariate adjustment. Spearman's correlation between the variables measured highlighted LPS as a potential modulator of the observed effects. In line with this findings, serum LPS and intracellular signaling in monocytes decreased with the three interventions (CR, p = 0.002; IF, p = 0.001; and KD, p = 0.001) compared to those in the AL group at the end of the study.

CONCLUSIONS

We conclude that these dietary interventions positively regulate mitochondrial bioenergetic health and improve the metabolic profile of monocytes in individuals with obesity via modulation of the gut microbiota. Moreover, the evaluation of mitochondrial function in monocytes could be used as an indicator of metabolic and inflammatory status, with potential applications in future clinical trials.

TRIAL REGISTRATION

This trial was registered with ClinicalTrials.gov (NCT05200468).

Digesting the complex metabolic effects of diet on the host and microbiome

The past 50 years of interdisciplinary research in humans and model organisms has delivered unprecedented insights into the mechanisms through which diet affects energy balance. However, translating these results to prevent and treat obesity and its associated diseases remains challenging. Given the vast scope of this literature, we focus this Review on recent conceptual advances in molecular nutrition targeting the management of energy balance, including emerging dietary and pharmaceutical interventions and their interactions with the human gut microbiome. Notably, multiple current dietary patterns of interest embrace moderate-to-high fat intake or prioritize the timing of eating over macronutrient intake. Furthermore, the rapid expansion of microbiome research findings has complicated multiple longstanding tenets of nutrition while also providing new opportunities for intervention. Continued progress promises more precise and reliable dietary recommendations that leverage our growing knowledge of the microbiome, the changing landscape of clinical interventions, and our molecular understanding of human biology.

Dynamic changes in butyrate levels regulate satellite cell homeostasis by preventing spontaneous activation during aging

The gut microbiota plays a pivotal role in systemic metabolic processes and in particular functions, such as developing and preserving the skeletal muscle system. However, the interplay between gut microbiota/metabolites and the regulation of satellite cell (SC) homeostasis, particularly during aging, remains elusive. We propose that gut microbiota and its metabolites modulate SC physiology and homeostasis throughout skeletal muscle development, regeneration, and aging process. Our investigation reveals that microbial dysbiosis manipulated by either antibiotic treatment or fecal microbiota transplantation from aged to adult mice, leads to the activation of SCs or a significant reduction in the total number. Furthermore, employing multi-omics (e.g., RNA-seq, 16S rRNA gene sequencing, and metabolomics) and bioinformatic analysis, we demonstrate that the reduced butyrate levels, alongside the gut microbial dysbiosis, could be the primary factor contributing to the reduction in the number of SCs and subsequent impairments during skeletal muscle aging. Meanwhile, butyrate supplementation can mitigate the antibiotics-induced SC activation irrespective of gut microbiota, potentially by inhibiting the proliferation and differentiation of SCs/myoblasts. The butyrate effect is likely facilitated through the monocarboxylate transporter 1 (Mct1), a lactate transporter enriched on membranes of SCs and myoblasts. As a result, butyrate could serve as an alternative strategy to enhance SC homeostasis and function during skeletal muscle aging. Our findings shed light on the potential application of microbial metabolites in maintaining SC homeostasis and preventing skeletal muscle aging.

Long term methionine restriction: Influence on gut microbiome and metabolic characteristics

The Methionine restriction (MR) diet has been shown to delay aging and extend lifespan in various model organisms. However, the long-term effects of MR diet on the gut microbiome composition remain unclear. To study this, male mice were started on MR and control diet regimens at 6 months and continued until 22 months of age. MR mice have reduced body weight, fat mass percentage, and bone mineral density while having increased lean mass percentage. MR mice also have increased insulin sensitivity along with increasing indirect calorimetry markers such as energy expenditure, oxygen consumption, carbon dioxide production, and glucose oxidation. Fecal samples were collected at 1 week, 18 weeks, and 57 weeks after the diet onset for 16S rRNA amplicon sequencing to study the gut microbiome composition. Alpha and beta diversity metrics detected changes occurring due to the timepoint variable, but no changes were detected due to the diet variable. The results from LEfSe analysis surprisingly showed that more bacterial taxa changes were linked to age rather than diet. Interestingly, we found that the long-term MR diet feeding induced smaller changes compared to short-term feeding. Specific taxa changes due to the diet were observed at the 1 or 18-week time points, including Ileibacterium, Odoribacter, Lachnoclostridium, Marinifilaceae, and Lactobacillaceae. Furthermore, there were consistent aging-associated changes across both groups, with an increase in Ileibacterium and Erysipelotrichaceae with age, while Eubacterium_coprostanoligenes_group, Ruminococcaceae, Peptococcaceae, and Peptococcus decreased with age.

Importance of temperature on immuno-metabolic regulation and cancer progression

Cancer immunotherapies emerge as promising strategies for restricting tumour growth. The tumour microenvironment (TME) has a major impact on the anti-tumour immune response and on the efficacy of the immunotherapies. Recent studies have linked changes in the ambient temperature with particular immuno-metabolic reprogramming and anti-cancer immune response in laboratory animals. Here, we describe the energetic balance of the organism during change in temperature, and link this to the immune alterations that could be of relevance for cancer, as well as for other human diseases. We highlight the contribution of the gut microbiota in modifying this interaction. We describe the overall metabolic response and underlying mechanisms of tumourigenesis in mouse models at varying ambient temperatures and shed light on their potential importance in developing therapeutics against cancer.

Caloric restriction for the immunometabolic control of human health

Nutrition affects all physiological processes occurring in our body, including those related to the function of the immune system; indeed, metabolism has been closely associated with the differentiation and activity of both innate and adaptive immune cells. While excessive energy intake and adiposity have been demonstrated to cause systemic inflammation, several clinical and experimental evidence show that calorie restriction (CR), not leading to malnutrition, is able to delay aging and exert potent anti-inflammatory effects in different pathological conditions. This review provides an overview of the ability of different CR-related nutritional strategies to control autoimmune, cardiovascular, and infectious diseases, as tested by preclinical studies and human clinical trials, with a specific focus on the immunological aspects of these interventions. In particular, we recapitulate the state of the art on the cellular and molecular mechanisms pertaining to immune cell metabolic rewiring, regulatory T cell expansion, and gut microbiota composition, which possibly underline the beneficial effects of CR. Although studies are still needed to fully evaluate the feasibility and efficacy of the nutritional intervention in clinical practice, the experimental observations discussed here suggest a relevant role of CR in lowering the inflammatory state in a plethora of different pathologies, thus representing a promising therapeutic strategy for the control of human health.

Gut microbiome-based therapies for alleviating cognitive impairment: state of the field, limitations, and future perspectives

Cognitive impairment (CI) is a multifaceted neurological condition that can trigger negative emotions and a range of concurrent symptoms, imposing significant public health and economic burdens on society. Therefore, it is imperative to discover a remedy for CI. Nevertheless, the mechanisms behind the onset of this disease are multifactorial, which makes the search for effective amelioration difficult and complex, hindering the search for effective measures. Intriguingly, preclinical research indicates that gut microbiota by influencing brain function, plays an important role in the progression of CI. Furthermore, numerous preclinical studies have highlighted the potential of probiotics, prebiotics, fecal microbiota transplantation (FMT), and diet in modulating the gut microbiota, thereby ameliorating CI symptoms. This review provides a comprehensive evaluation of CI pathogenesis, emphasizing the contribution of gut microbiota disorders to CI development. It also summarizes and discusses current strategies and mechanisms centered on the synergistic role of gut microbiota modulation in the microbiota-gut-brain axis in CI development. Finally, problems with existing approaches are contemplated and the development of microbial modulation strategies as therapeutic approaches to promote and restore brain cognition is discussed. Further research considerations and directions are highlighted to provide ideas for future CI prevention and treatment strategies.

Effects of ruminal lipopolysaccharide exposure on primary bovine ruminal epithelial cells

The objective of this study was to investigate the immunopotential of ruminal lipopolysaccharides (LPS) on cultured primary bovine rumen epithelial cells (REC). Primary bovine REC were isolated from 6 yearling steers and grown in culture for 3 experiments. Experiment 1 aimed to determine the immunopotential of ruminal LPS, experiment 2 aimed to assess tolerance to chronic LPS exposure, and experiment 3 aimed to evaluate antagonistic interactions between ruminal and Escherichia coli LPS. In experiments 1 and 2, REC were exposed to nonpyrogenic water, 20 μg/mL E. coli LPS (EC20), 10 μg/mL ruminal LPS, 20 μg/mL ruminal LPS, and 40 μg/mL ruminal LPS, either continuously or intermittently. For the continuous exposure, REC underwent a 6 h exposure, whereas for the intermittent exposure, the procedure was: (1) a 12 h continuous exposure to treatments followed by LPS removal for 24 h and then another 12 h of exposure (RPT), and (2) a 12 h continuous exposure to treatments followed by LPS removal and a recovery period of 36 h (RCV). In experiment 3, REC were exposed to nonpyrogenic water, 1 μg/mL E. coli LPS, 1 μg/mL ruminal LPS to 1 μg/mL E. coli LPS, 10 μg/mL ruminal LPS to 1 μg/mL E. coli LPS, and 50 μg/mL ruminal LPS to 1 μg/mL E. coli LPS. Each experiment was done as a complete randomized block design with 6 REC donors. The REC-donor was used as blocking factor. Each treatment had 2 technical replicates, and treatment responses for all data were analyzed with the MIXED procedure of SAS. For all experiments, total RNA was extracted from REC and real-time quantitative PCR was performed to determine the relative expression of genes for toll-like receptors (TLR2 and TLR4), proinflammatory cytokines (TNF, IL1B, and IL6), chemokines (CXCL2 and CXCL8), growth factor-like cytokines (CSF2 and TGFB1), and a lipid mediator (PTGS2). In experiment 1, the targeted genes were upregulated by EC20, whereas all ruminal LPS treatments resulted in a lower transcript abundance. Regarding RPT, and RCV condition, in experiment 2, the expression of targeted genes was not affected or was at a lower abundance to EC20 when compared with ruminal LPS treatments. Lastly, in experiment 3, all targeted genes resulted in lower or similar transcript abundance on all ruminal LPS ratios. Overall, our results indicate that ruminal LPS have a limited capacity to activate the TLR4/NF-kB pathway and to induce the expression of inflammatory genes.

Microbiota Implications in Endocrine-Related Diseases: From Development to Novel Therapeutic Approaches

This comprehensive review article delves into the critical role of the human microbiota in the development and management of endocrine-related diseases. We explore the complex interactions between the microbiota and the endocrine system, emphasizing the implications of microbiota dysbiosis for the onset and progression of various endocrine disorders. The review aims to synthesize current knowledge, highlighting recent advancements and the potential of novel therapeutic approaches targeting microbiota-endocrine interactions. Key topics include the impact of microbiota on hormone regulation, its role in endocrine pathologies, and the promising avenues of microbiota modulation through diet, probiotics, prebiotics, and fecal microbiota transplantation. We underscore the importance of this research in advancing personalized medicine, offering insights for more tailored and effective treatments for endocrine-related diseases.

The influence of the gut microbiome on ovarian aging

Ovarian aging occurs prior to the aging of other organ systems and acts as the pacemaker of the aging process of multiple organs. As life expectancy has increased, preventing ovarian aging has become an essential goal for promoting extended reproductive function and improving bone and genitourinary conditions related to ovarian aging in women. An improved understanding of ovarian aging may ultimately provide tools for the prediction and mitigation of this process. Recent studies have suggested a connection between ovarian aging and the gut microbiota, and alterations in the composition and functional profile of the gut microbiota have profound consequences on ovarian function. The interaction between the gut microbiota and the ovaries is bidirectional. In this review, we examine current knowledge on ovary-gut microbiota crosstalk and further discuss the potential role of gut microbiota in anti-aging interventions. Microbiota-based manipulation is an appealing approach that may offer new therapeutic strategies to delay or reverse ovarian aging.

Microbiota configuration determines nutritional immune optimization

Mild or transient dietary restriction (DR) improves many aspects of health and aging. Emerging evidence from us and others has demonstrated that DR also optimizes the development and quality of immune responses. However, the factors and mechanisms involved remain to be elucidated. Here, we propose that DR-induced optimization of immunological memory requires a complex cascade of events involving memory T cells, the intestinal microbiota, and myeloid cells. Our findings suggest that DR enhances the ability of memory T cells to recruit and activate myeloid cells in the context of a secondary infection. Concomitantly, DR promotes the expansion of commensal Bifidobacteria within the large intestine, which produce the short-chain fatty acid acetate. Acetate conditioning of the myeloid compartment during DR enhances the capacity of these cells to kill pathogens. Enhanced host protection during DR is compromised when Bifidobacteria expansion is prevented, indicating that microbiota configuration and function play an important role in determining immune responsiveness to this dietary intervention. Altogether, our study supports the idea that DR induces both memory T cells and the gut microbiota to produce distinct factors that converge on myeloid cells to promote optimal pathogen control. These findings suggest that nutritional cues can promote adaptation and co-operation between multiple immune cells and the gut microbiota, which synergize to optimize immunity and protect the collective metaorganism.

Effects of Calorie Restriction and Fasting on Macrophage: Potential Impact on Disease Outcomes?

Energy restriction, including calorie restriction and fasting, has garnered significant attention for its potential therapeutic effects on a range of chronic diseases (such as diabetes, obesity, and cancer) and aging. Since macrophages are critical players in many diseases, their response to energy restriction may impact disease outcomes. However, the diverse metabolic patterns and functions of macrophages can lead to variability in the effects of energy restriction on macrophages across different tissues and disease states. This review outlines the effects of energy restriction on macrophages in several diseases, offering valuable guidance for future studies and insights into the clinical applications of calorie restriction and fasting.

Intestinal microbiota: a new perspective on delaying aging?

The global aging situation is severe, and the medical pressures associated with aging issues should not be underestimated. The need and feasibility of studying aging and intervening in aging have been confirmed. Aging is a complex natural physiological progression, which involves the irreversible deterioration of body cells, tissues, and organs with age, leading to enhanced risk of disease and ultimately death. The intestinal microbiota has a significant role in sustaining host dynamic balance, and the study of bidirectional communication networks such as the brain-gut axis provides important directions for human disease research. Moreover, the intestinal microbiota is intimately linked to aging. This review describes the intestinal microbiota changes in human aging and analyzes the causal controversy between gut microbiota changes and aging, which are believed to be mutually causal, mutually reinforcing, and inextricably linked. Finally, from an anti-aging perspective, this study summarizes how to achieve delayed aging by targeting the intestinal microbiota. Accordingly, the study aims to provide guidance for further research on the intestinal microbiota and aging.

NAD+ rescues aging-induced blood-brain barrier damage via the CX43-PARP1 axis

Blood-brain barrier (BBB) function deteriorates during aging, contributing to cognitive impairment and neurodegeneration. It is unclear what drives BBB leakage in aging and how it can be prevented. Using single-nucleus transcriptomics, we identified decreased connexin 43 (CX43) expression in cadherin-5+ (Cdh5+) cerebral vascular cells in naturally aging mice and confirmed it in human brain samples. Global or Cdh5+ cell-specific CX43 deletion in mice exacerbated BBB dysfunction during aging. The CX43-dependent effect was not due to its canonical gap junction function but was associated with reduced NAD+ levels and mitochondrial dysfunction through NAD+-dependent sirtuin 3 (SIRT3). CX43 interacts with and negatively regulates poly(ADP-ribose) polymerase 1 (PARP1). Pharmacologic inhibition of PARP1 by olaparib or nicotinamide mononucleotide (NMN) supplementation rescued NAD+ levels and alleviated aging-associated BBB leakage. These findings establish the endothelial CX43-PARP1-NAD+ pathway's role in vascular aging and identify a potential therapeutic strategy to combat aging-associated BBB leakage with neuroprotective implications.

Therapeutic modulation of the liver immune microenvironment

Inflammation is a hallmark of progressive liver diseases such as chronic viral or immune-mediated hepatitis, alcohol-associated liver disease, and NAFLD. Preclinical and clinical studies have provided robust evidence that cytokines and related cellular stress sensors in innate and adaptive immunity orchestrate hepatic disease processes. Unresolved inflammation and liver injury result in hepatic scarring, fibrosis, and cirrhosis, which may culminate in HCC. Liver diseases are accompanied by gut dysbiosis and a bloom of pathobionts, fueling hepatic inflammation. Anti-inflammatory strategies are extensively used to treat human immune-mediated conditions beyond the liver, while evidence for immunomodulatory therapies and cell therapy-based strategies in liver diseases is only emerging. The development and establishment of novel immunomodulatory therapies for chronic liver diseases has been dampened by several clinical challenges, such as invasive monitoring of therapeutic efficacy with liver biopsy in clinical trials and risk of DILI in several studies. Such aspects prevented advancements of novel medical therapies for chronic inflammatory liver diseases. New concepts modulating the liver immune environment are studied and eagerly awaited to improve the management of chronic liver diseases in the future.

The Role of Diet and Gut Microbiota Interactions in Metabolic Homeostasis

Diet is a pivotal determinant in shaping the structure and function of resident microorganisms in the gut through different food components, nutritive proportion, and calories. The effects of diet on host metabolism and physiology can be mediated through the gut microbiota. Gut microbiota-derived metabolites have been shown to regulate glucose and lipid metabolism, energy consumption, and the immune system. On the other hand, emerging evidence indicates that baseline gut microbiota could predict the efficacy of diet intervention, highlighting gut microbiota can be harnessed as a biomarker in personalized nutrition. In this review, the alterations of gut microbiota in different dietary components and dietary patterns, and the potential mechanisms in the diet-microbiota crosstalk are summarized to understand the interactions of diet and gut microbiota on the impact of metabolic homeostasis.

Short chain fatty acids and GIT hormones mitigate gut barrier disruption in high fat diet fed rats supplemented by synbiotics

High fat diet (HFD) predisposes to many metabolic changes; it may disrupt gut barrier integrity and gut microbiota composition. Synbiotic supplementation may promote host’s metabolic health by selective activation of the healthy microorganisms. This study aimed to probe the interaction between synbiotic supplementation, gut microbiota and gut hormones in HFD states. Twenty-seven adult male albino rats, 3 groups, group I: control, group II: HFD received HFD for 12 weeks and group III: synbiotic-supplemented HFD received synbiotic in the last 6 weeks. The anthropometric measurments were measured. Liver transaminases, lipid profile, parameters of insulin resistance, serum serotonin, glucagon like polypeptide-1 (GLP-1), oxidant/antioxidant markers (MDA/GPx), zonulin levels and quantitative cecal short chain fatty acids (SCFA) were assessed. Samples of liver and colon were employed for histopathological studies. Compared to HFD group, synbiotic led to a significant reduction in anthropometric measurements, liver enzymes, atherogenic index, HOMA-IR and MDA denoting improved dyslipidemia, insulin resistance and oxidative state. Moreover, synbiotic supplementation decreased serum zonulin and increased both serum serotonin, GLP-1 and cecal SCFAs. Synbiotic supplementation ameliorated the metabolic derangements and the disturbed integrity of the intestinal barrier induced by HFD. As synbiotics can increase gut hormones (serum GLP-1&serotonin) and SCFAs.

MetaPhlAn 4 profiling of unknown species-level genome bins improves the characterization of diet-associated microbiome changes in mice

Mouse models are key tools for investigating host-microbiome interactions. However, shotgun metagenomics can only profile a limited fraction of the mouse gut microbiome. Here, we employ a metagenomic profiling method, MetaPhlAn 4, which exploits a large catalog of metagenome-assembled genomes (including 22,718 metagenome-assembled genomes from mice) to improve the profiling of the mouse gut microbiome. We combine 622 samples from eight public datasets and an additional cohort of 97 mouse microbiomes, and we assess the potential of MetaPhlAn 4 to better identify diet-related changes in the host microbiome using a meta-analysis approach. We find multiple, strong, and reproducible diet-related microbial biomarkers, largely increasing those identifiable by other available methods relying only on reference information. The strongest drivers of the diet-induced changes are uncharacterized and previously undetected taxa, confirming the importance of adopting metagenomic methods integrating metagenomic assemblies for comprehensive profiling.

A nexus of dietary restriction and gut microbiota: Recent insights into metabolic health

In recent times, dietary restriction (DR) has received considerable attention for its promising effects on metabolism and longevity. Previous studies on DR have mainly focused on the health benefits produced by different restriction patterns, whereas comprehensive reviews of the role of gut microbiota during DR are limited. In this review, we discuss the effects of caloric restriction, fasting, protein restriction, and amino acid restriction from a microbiome perspective. Furthermore, the underlying mechanisms by which DR affects metabolic health by regulating intestinal homeostasis are summarized. Specifically, we reviewed the impacts of different DRs on specific gut microbiota. Additionally, we put forward the limitations of the current research and suggest the development of personalized microbes-directed DR for different populations and corresponding next-generation sequencing technologies for accurate microbiological analysis. DR effectively modulates the composition of the gut microbiota and microbial metabolites. In particular, DR markedly affects the rhythmic oscillation of microbes which may be related to the circadian clock system. Moreover, increasing evidence supports that DR profoundly improves metabolic syndrome, inflammatory bowel disease, and cognitive impairment. To summarize, DR may be an effective and executable dietary manipulation strategy for maintaining metabolic health, however, further investigation is needed to elucidate the underlying mechanisms.

Caloric restriction remodels the hepatic chromatin landscape and bile acid metabolism by modulating the gut microbiota

BACKGROUND

Caloric restriction (CR) has been known to promote health by reprogramming metabolism, yet little is known about how the epigenome and microbiome respond during metabolic adaptation to CR.

RESULTS

We investigate chromatin modifications, gene expression, as well as alterations in microbiota in a CR mouse model. Collectively, short-term CR leads to altered gut microbial diversity and bile acid metabolism, improving energy expenditure. CR remodels the hepatic enhancer landscape at genomic loci that are enriched for binding sites for signal-responsive transcription factors, including HNF4α. These alterations reflect a dramatic reprogramming of the liver transcriptional network, including genes involved in bile acid metabolism. Transferring CR gut microbiota into mice fed with an obesogenic diet recapitulates the features of CR-related bile acid metabolism along with attenuated fatty liver.

CONCLUSIONS

These findings suggest that CR-induced microbiota shapes the hepatic epigenome followed by altered expression of genes responsible for bile acid metabolism.

Calorie restriction ameliorates hyperglycemia, modulates the disordered gut microbiota, and mitigates metabolic endotoxemia and inflammation in type 2 diabetic rats

PURPOSE

The effects of calorie restriction (CR) on gut microbiota and the mechanism of CR ameliorating hyperglycemia in streptozotocin (STZ)-induced T2DM model rats were explored.

METHODS

High-fat diet and STZ injection were applied to induce T2DM model rats. Rats were divided into the following three groups: the control-diet ad libitum group, the T2DM model group fed with ad libitum diet, and the T2DM group fed with 30% restriction diet. 16S rRNA sequencing was used to determine the bacterial communities. Lipopolysaccharide (LPS)-binding protein (LBP), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were measured.

RESULTS

Glucose tolerance and insulin sensitivity were improved by CR, as well as the levels of fasting and random plasma glucose. Besides, CR not only modulated the overall structure of gut microbiota but also had selective enrichment in anti-inflammatory bacteria such as Lachnospiraceae_NK4A136_group, Ruminococcaceae_9, Allobaculum, Alistipes, and Oscillibacter, and decreased pro-inflammatory pathogenic bacteria such as Bacteroides, Lachnoclostridium, and Bifidobacterium. Tax4Fun indicated that CR could regulate related functional pathways such as lipopolysaccharide biosynthesis, and the plasma levels of LBP, IL-6, and TNF-α were markedly reduced by CR, suggesting the mechanism of CR ameliorating hyperglycemia may associate with the modulation of disordered gut microbiota and the reduction of metabolic endotoxemia and inflammation.

CONCLUSION

CR could ameliorate hyperglycemia, the mechanism of which may associate with the alteration of the overall structure of gut microbiota, restoration of disordered microbiota function, and the downregulation of metabolic endotoxemia and inflammation in diabetic rats.

Remodelling of the intestinal ecosystem during caloric restriction and fasting

Benefits of fasting and caloric restriction on host metabolic health are well established, but less is known about the effects on the gut microbiome and how this impacts renewal of the intestinal mucosa. What has been repeatedly shown during fasting, however, is that bacteria utilising host-derived substrates proliferate at the expense of those relying on dietary substrates. Considering the increased recognition of the gut microbiome's role in maintaining host (metabolic) health, disentangling host-microbe interactions and establishing their physiological relevance in the context of fasting and caloric restriction is crucial. Such insights could aid in moving away from associations of gut bacterial signatures with metabolic diseases consistently reported in observational studies to potentially establishing causality. Therefore, this review aims to summarise what is currently known or still controversial about the interplay between fasting and caloric restriction, the gut microbiome and intestinal tissue physiology.

Trust the gut: outcomes of gut microbiota transplant in metabolic and cognitive disorders

Type 2 diabetes mellitus (T2DM) is a main public health concern, with increasing prevalence and growingly premature onset in children, in spite of emerging and successful therapeutic options. T2DM promotes brain aging, and younger age at onset is associated with a higher risk of subsequent dementia. Preventive strategies should address predisposing conditions, like obesity and metabolic syndrome, and be started from very early and even prenatal life. Gut microbiota is an emerging target in obesity, diabetes and neurocognitive diseases, which could be safely modulated since pregnancy and infancy. Many correlative studies have supported its involvement in disease pathophysiology. Faecal material transplantation (FMT) studies have been conducted in clinical and preclinical settings to deliver cause-effect proof and mechanistic insights. This review provides a comprehensive overview of studies in which FMT was used to cure or cause obesity, metabolic syndrome, T2DM, cognitive decline and Alzheimer's disease, including the evidence available in early life. Findings were analysed to dissect consolidated from controversial results, highlighting gaps and possible future directions.

Impact of caloric restriction on the gut microbiota

Caloric restriction (CR) and related time-restricted diets have been popularized as means of preventing metabolic disease while improving general well-being. However, evidence as to their long-term efficacy, adverse effects, and mechanisms of activity remains incompletely understood. The gut microbiota is modulated by such dietary approaches, yet causal evidence to its possible downstream impacts on host metabolism remains elusive. Herein, we discuss the positive and adverse influences of restrictive dietary interventions on gut microbiota composition and function, and their collective impacts on host health and disease risk. We highlight known mechanisms of microbiota influences on the host, such as modulation of bioactive metabolites, while discussing challenges in achieving mechanistic dietary-microbiota insights, including interindividual variability in dietary responses as well as other methodological and conceptual challenges. In all, causally understanding the impact of CR approaches on the gut microbiota may enable to better decode their overall influences on human physiology and disease.

Mitochondrial Transfer Regulates Cell Fate Through Metabolic Remodeling in Osteoporosis

Mitochondria are the powerhouse of eukaryotic cells, which regulate cell metabolism and differentiation. Recently, mitochondrial transfer between cells has been shown to direct recipient cell fate. However, it is unclear whether mitochondria can translocate to stem cells and whether this transfer alters stem cell fate. Here, mesenchymal stem cell (MSC) regulation is examined by macrophages in the bone marrow environment. It is found that macrophages promote osteogenic differentiation of MSCs by delivering mitochondria to MSCs. However, under osteoporotic conditions, macrophages with altered phenotypes, and metabolic statuses release oxidatively damaged mitochondria. Increased mitochondrial transfer of M1-like macrophages to MSCs triggers a reactive oxygen species burst, which leads to metabolic remodeling. It is showed that abnormal metabolism in MSCs is caused by the abnormal succinate accumulation, which is a key factor in abnormal osteogenic differentiation. These results reveal that mitochondrial transfer from macrophages to MSCs allows metabolic crosstalk to regulate bone homeostasis. This mechanism identifies a potential target for the treatment of osteoporosis.

Influences of calorie restriction and lipopolysaccharide therapy on inflammation, cytokine response, and cell proliferation in pancreatic adenocarcinoma mouse model

The study aimed to investigate the effects of lipopolysaccharide (LPS) alone and in combination with calorie restriction (CR) on the pancreatic tissues in C57BL/6 mice modeled with pancreatic ductal adenocarcinoma (PDAC). Forty male C57BL/6 mice (10-13 weeks old) were divided into five groups; LPS, LPS + CR, PDAC, PDAC + LPS, and PDAC + LPS + CR. Nuclear factor kappa B (NF-κβ), interleukin-6 (IL-6), and c-Jun N-terminal kinases (JNK) mRNA expression levels were measured in pancreatic tissues. NF-κβ, IL-6, JNK, and proliferating cell nuclear antigen (PCNA) peptide levels were determined by immunohistochemistry. Oxidative stress markers and antioxidant enzyme activities were determined spectrophotometrically. TH1/TH2 cytokine measurements were determined by a flow cytometer. It was detected that the number of PCNA immune + cells in the PDAC + LPS + CR group was significantly lower than in the PDAC and PDAC + LPS groups (p < 0.01, p < 0.05 respectively). PDAC + LPS + CR group's plasma interferon-gamma (IFN-γ), IL-6, IL-2, tumor necrosis factor-alpha, IL-3, and IL-4 levels were found to be significantly lower than the PDAC group (p < 0.01, p < 0.001, p < 0.01, p < 0.05, p < 0.01, and p < 0.05 respectively). According to our findings, the combination of low-dose LPS and 40% CR was found to be more effective in PDAC model mice.

The person-to-person transmission landscape of the gut and oral microbiomes

The human microbiome is an integral component of the human body and a co-determinant of several health conditions1,2. However, the extent to which interpersonal relations shape the individual genetic makeup of the microbiome and its transmission within and across populations remains largely unknown3,4. Here, capitalizing on more than 9,700 human metagenomes and computational strain-level profiling, we detected extensive bacterial strain sharing across individuals (more than 10 million instances) with distinct mother-to-infant, intra-household and intra-population transmission patterns. Mother-to-infant gut microbiome transmission was considerable and stable during infancy (around 50% of the same strains among shared species (strain-sharing rate)) and remained detectable at older ages. By contrast, the transmission of the oral microbiome occurred largely horizontally and was enhanced by the duration of cohabitation. There was substantial strain sharing among cohabiting individuals, with 12% and 32% median strain-sharing rates for the gut and oral microbiomes, and time since cohabitation affected strain sharing more than age or genetics did. Bacterial strain sharing additionally recapitulated host population structures better than species-level profiles did. Finally, distinct taxa appeared as efficient spreaders across transmission modes and were associated with different predicted bacterial phenotypes linked with out-of-host survival capabilities. The extent of microorganism transmission that we describe underscores its relevance in human microbiome studies5, especially those on non-infectious, microbiome-associated diseases.

Characterizing the gut microbiome changes with aging in a novel Alzheimer's disease rat model

Alzheimer's disease (AD) is one of the most devastating diseases currently in the world with no effective treatments. There is increasing evidence that the gut microbiome plays a role in AD. Here we set out to study the age-related changes in the microbiome of the Tgf344-AD rats. We performed 16S ribosomal RNA sequencing on the fecal samples of male rats at 14 and 20 months of age. We found the Tgf344-AD rats to have decreased microbial diversity compared to controls at 14 months of age and this was found to be opposite at 20 months of age. Interestingly, we found a distinctive shift in the microbial community structure of the rats with aging along with changes in the microbiota composition. Some of the observed changes in the Tgf344AD rats were in the genera Bifidobacterium, Ruminococcus, Parasutterella, Lachnoclostridium and Butyricicoccus. Other age-related changes occuring in both the Tgf344-AD and WT control rats were decreases in Enterohaldus, Escherichia Shigella, Rothia and increase in Turicibacter and Clostrium_senso_stricto. Our study has shown that gut microbiota changes occurs in this Alzheimer's disease rat model.

The antitumour effects of caloric restriction are mediated by the gut microbiome

Calorie restriction (CR) and intermittent fasting (IF) without malnutrition reduce the risk of cancer development. Separately, CR and IF can also lead to gut microbiota remodelling. However, whether the gut microbiota has a role in the antitumour effect related to CR or IF is still unknown. Here we show that CR, but not IF, protects against subcutaneous MC38 tumour formation through a mechanism that is dependent on the gut microbiota in female mice. After CR, we identify enrichment of Bifidobacterium through 16S rRNA sequencing of the gut microbiome. Moreover, Bifidobacterium bifidum administration is sufficient to rescue the antitumour effect of CR in microbiota-depleted mice. Mechanistically, B. bifidum mediates the CR-induced antitumour effect through acetate production and this effect is also dependent on the accumulation of interferon-γ⁺CD8⁺ T cells in the tumour microenvironment. Our results demonstrate that CR can modulate the gut taxonomic composition, which should be of oncological significance in tumour growth kinetics and cancer immunosurveillance.

Decreased Enterobacteriaceae translocation due to gut microbiota remodeling mediates the alleviation of premature aging by a high-fat diet

Aging-associated microbial dysbiosis exacerbates various disorders and dysfunctions, and is a major contributor to morbidity and mortality in the elderly, but the underlying cause of this aging-related syndrome is confusing. SIRT6 knockout (SIRT6 KO) mice undergo premature aging and succumb to death by 4 weeks, and are therefore useful as a premature aging research model. Here, fecal microbiota transplantation from SIRT6 KO mice into wild-type (WT) mice phenocopies the gut dysbiosis and premature aging observed in SIRT6 KO mice. Conversely, an expanded lifespan was observed in SIRT6 KO mice when transplanted with microbiota from WT mice. Antibiotic cocktail treatment attenuated inflammation and cell senescence in KO mice, directly suggesting that gut dysbiosis contributes to the premature aging of SIRT6 KO mice. Increased Enterobacteriaceae translocation, driven by the overgrowth of Escherichia coli, is the likely mechanism for the premature aging effects of microbiome dysregulation, which could be reversed by a high-fat diet. Our results provide a mechanism for the causal link between gut dysbiosis and aging, and support a beneficial effect of a high-fat diet for correcting gut dysbiosis and alleviating premature aging. This study provides a rationale for the integration of microbiome-based high-fat diets into therapeutic interventions against aging-associated diseases.

High-protein diet prevents fat mass increase after dieting by counteracting Lactobacillus-enhanced lipid absorption

Dietary restriction is widely used to reduce fat mass and lose weight in individuals with or without obesity; however, weight regain after dieting is still a big challenge, and the underlying mechanisms remain largely elusive. Here we show that refeeding after various types of dieting induces quick fat accumulation in mice and enhanced intestinal lipid absorption contributes to post-dieting fat mass increase. Moreover, refeeding after short-term dietary restriction is accompanied by an increase in intestinal Lactobacillus and its metabolites, which contributes to enhanced intestinal lipid absorption and post-dieting fat mass increase; however, refeeding a high-protein diet after short-term dietary restriction attenuates intestinal lipid absorption and represses fat accumulation by preventing Lactobacillus growth. Our results provide insight into the mechanisms underlying fat mass increase after dieting. We also propose that targeting intestinal Lactobacillus to inhibit intestinal lipid absorption via high-protein diet or antibiotics is likely an effective strategy to prevent obesity after dieting.

Anti-inflammatory mechanisms of polyphenols in adipose tissue: role of gut microbiota, intestinal barrier integrity and zinc homeostasis

Obesity is associated with an imbalance of micro-and macro-nutrients, gut dysbiosis, and a "leaky" gut phenomenon. Polyphenols, such as curcumin, resveratrol, and anthocyanins may alleviate the systemic effects of obesity, potentially by improving gut microbiota, intestinal barrier integrity (IBI), and zinc homeostasis. The essential micronutrient zinc plays a crucial role in the regulation of enzymatic processes, including inflammation, maintenance of the microbial ecology, and intestinal barrier integrity. In this review, we focus on IBI- which prevents intestinal lipopolysaccharide (LPS) leakage - as a critical player in polyphenol-mediated protective effects against obesity-associated white adipose tissue (WAT) inflammation. This occurs through mechanisms that block the movement of the bacterial endotoxin LPS across the gut barrier. Available research suggests that polyphenols reduce WAT and systemic inflammation via crosstalk with inflammatory NF-κB, the mammalian target of rapamycin (mTOR) signaling and zinc homeostasis.

Caloric Restriction, Friend or Foe: Effects on Metabolic Status in Association with the Intestinal Microbiome and Metabolome

Daily calorie restriction (CR) has shown benefits on weight loss and alleviation of metabolic disorders. We investigated the effects of three CR regimens, i.e., 20% (CR-20), 40% (CR-40), and 60% (CR-60) less than the average daily calorie intake, respectively, on the metabolic parameters, gut microbiome composition, and its related metabolites in healthy mice. Compared with mice fed ad libitum (AL), CR dose-dependently reduced the body weight, and weights of liver and epididymal adipose tissues, and enhanced the insulin sensitivity, glucose tolerance, and lipid homeostasis. Moreover, expression levels of intestinal tight junction proteins (i.e., ZO-1, claudin, and occludin) were significantly promoted by CR than those of AL mice, demonstrating the CR-induced improvement of the intestinal barrier integrity. CR contributed to the enrichment of beneficial microbiota (e.g., Lactobacillus, Bacteroides, and Akkermansia) and increased propionic acid levels. Notably, CR-60 deleteriously caused liver injury, and enhanced hepatic inflammatory cytokines (i.e., IL-1, IL-6, and TNF-α) and lipopolysaccharides, which were accompanied by high levels of trimethylamine (TMA) and trimethylamine oxide (TMAO) in relation to CR-60-altered gut microbiota structure and fecal metabolome. Additionally, we found differential impacts of CR-20, -40, or -60 on amino acid absorption and metabolism. Our findings support the health-promoting benefits of 60-80% daily calorie intake on the metabolic status by regulating the gut microbiota in healthy mice. However, excessive CR caused liver injury and gut microbiota-dependent elevation of TMAO. The differential effects of CR regimens on the intestinal microbiome and fecal metabolome provide novel insights into the dietary pattern-gut microbiome interactions linked with host metabolism.

Gut-liver axis: Pathophysiological concepts and clinical implications

Bidirectional crosstalk along the gut-liver axis controls gastrointestinal health and disease and exploits environmental and host mediators. Nutrients, microbial antigens, metabolites, and bile acids regulate metabolism and immune responses in the gut and liver, which reciprocally shape microbial community structure and function. Perturbation of such host-microbe interactions is observed in a variety of experimental liver diseases and is facilitated by an impaired intestinal barrier, which is fueling hepatic inflammation and disease progression. Clinical evidence describes perturbation of the gut-liver crosstalk in non-alcoholic fatty liver disease, alcoholic liver disease, and primary sclerosing cholangitis. In liver cirrhosis, a common sequela of these diseases, the intestinal microbiota and microbial pathogen-associated molecular patterns constitute liver inflammation and clinical complications, such as hepatic encephalopathy. Understanding the intricate metabolic interplay between the gut and liver in health and disease opens an avenue for targeted therapies in the future, which is probed in controlled clinical trials.

Dysbiosis and Gastrointestinal Surgery: Current Insights and Future Research

Surgery of the gastrointestinal tract can result in deep changes among the gut commensals in terms of abundance, function and health consequences. Elective colorectal surgery can occur for neoplastic or inflammatory bowel disease; in these settings, microbiota imbalance is described as a preoperative condition, and it is linked to post-operative complications, as well. The study of bariatric patients led to several insights into the role of gut microbiota in obesity and after major surgical injuries. Preoperative dysbiosis and post-surgical microbiota reassessment are still poorly understood, and they could become a key part of preventing post-surgical complications. In the current review, we outline the most recent literature regarding agents and molecular pathways involved in pre- and post-operative dysbiosis in patients undergoing gastrointestinal surgery. Defining the standard method for microbiota assessment in these patients could set up the future approach and clinical practice.

Fluoride induced leaky gut and bloom of Erysipelatoclostridium ramosum mediate the exacerbation of obesity in high-fat-diet fed mice

INTRODUCTION

Fluoride is widely presented in drinking water and foods. A strong relation between fluoride exposure and obesity has been reported. However, the potential mechanisms on fluoride-induced obesity remain unexplored. Objectives and methods The effects of fluoride on the obesity were investigated using mice model. Furthermore, the role of gut homeostasis in exacerbation of the obesity induced by fluoride was evaluated. Results The results showed that fluoride alone did not induce obesity in normal diet (ND) fed mice, whereas, it could trigger exacerbation of obesity in high-fat diet (HFD) fed mice. Fluoride impaired intestinal barrier and activated Toll-like receptor 4 (TLR4) signaling to induce obesity, which was further verified in TLR4^-/- mice. Furthermore, fluoride could deteriorate the gut microbiota in HFD mice. The fecal microbiota transplantation from fluoride-induced mice was sufficient to induce obesity, while the exacerbation of obesity by fluoride was blocked upon gut microbiota depletion. The fluoride-induced bloom of Erysipelatoclostridium ramosum was responsible for exacerbation of obesity. In addition, a potential strategy for prevention of fluoride-induced obesity was proposed by intervention with polysaccharides from Fuzhuan brick tea. Conclusion Overall, these results provide the first evidence of a comprehensive cross-talk mechanism between fluoride and obesity in HFD fed mice, which is mediated by gut microbiota and intestinal barrier. E. ramosum was identified as a crucial mediator of fluoride induced obesity, which could be explored as potential target for prevention and treatment of obesity with exciting translational value.

Multiomics assessment of dietary protein titration reveals altered hepatic glucose utilization

Dietary protein restriction (PR) has rapid effects on metabolism including improved glucose and lipid homeostasis, via multiple mechanisms. Here, we investigate responses of fecal microbiome, hepatic transcriptome, and hepatic metabolome to six diets with protein from 18% to 0% of energy in mice. PR alters fecal microbial composition, but metabolic effects are not transferable via fecal transplantation. Hepatic transcriptome and metabolome are significantly altered in diets with lower than 10% energy from protein. Changes upon PR correlate with calorie restriction but with a larger magnitude and specific changes in amino acid (AA) metabolism. PR increases steady-state aspartate, serine, and glutamate and decreases glucose and gluconeogenic intermediates. ¹³C6 glucose and glycerol tracing reveal increased fractional enrichment in aspartate, serine, and glutamate. Changes remain intact in hepatic ATF4 knockout mice. Together, this demonstrates an ATF4-independent shift in gluconeogenic substrate utilization toward specific AAs, with compensation from glycerol to promote a protein-sparing response.

Adipose Tissue Aging and Metabolic Disorder, and the Impact of Nutritional Interventions

Adipose tissue is the largest and most active endocrine organ, involved in regulating energy balance, glucose and lipid homeostasis and immune function. Adipose tissue aging processes are associated with brown adipose tissue whitening, white adipose tissue redistribution and ectopic deposition, resulting in an increase in age-related inflammatory factors, which then trigger a variety of metabolic syndromes, including diabetes and hyperlipidemia. Metabolic syndrome, in turn, is associated with increased inflammatory factors, all-cause mortality and cognitive impairment. There is a growing interest in the role of nutritional interventions in adipose tissue aging. Nowadays, research has confirmed that nutritional interventions, involving caloric restriction and the use of vitamins, resveratrol and other active substances, are effective in managing adipose tissue aging’s adverse effects, such as obesity. In this review we summarized age-related physiological characteristics of adipose tissue, and focused on what nutritional interventions can do in improving the retrogradation and how they do this.

Dietary regulation in health and disease

Nutriments have been deemed to impact all physiopathologic processes. Recent evidences in molecular medicine and clinical trials have demonstrated that adequate nutrition treatments are the golden criterion for extending healthspan and delaying ageing in various species such as yeast, drosophila, rodent, primate and human. It emerges to develop the precision-nutrition therapeutics to slow age-related biological processes and treat diverse diseases. However, the nutritive advantages frequently diversify among individuals as well as organs and tissues, which brings challenges in this field. In this review, we summarize the different forms of dietary interventions extensively prescribed for healthspan improvement and disease treatment in pre-clinical or clinical. We discuss the nutrient-mediated mechanisms including metabolic regulators, nutritive metabolism pathways, epigenetic mechanisms and circadian clocks. Comparably, we describe diet-responsive effectors by which dietary interventions influence the endocrinic, immunological, microbial and neural states responsible for improving health and preventing multiple diseases in humans. Furthermore, we expatiate diverse patterns of dietotheroapies, including different fasting, calorie-restricted diet, ketogenic diet, high-fibre diet, plants-based diet, protein restriction diet or diet with specific reduction in amino acids or microelements, potentially affecting the health and morbid states. Altogether, we emphasize the profound nutritional therapy, and highlight the crosstalk among explored mechanisms and critical factors to develop individualized therapeutic approaches and predictors.

Downregulation of peripheral lipopolysaccharide binding protein impacts on perigonadal adipose tissue only in female mice

BACKGROUND AND AIMS

The sexual dimorphism in fat-mass distribution and circulating leptin and insulin levels is well known, influencing the progression of obesity-associated metabolic disease. Here, we aimed to investigate the possible role of lipopolysaccharide-binding protein (LBP) in this sexual dimorphism.

METHODS

The relationship between plasma LBP and fat mass was evaluated in 145 subjects. The effects of Lbp downregulation, using lipid encapsulated unlocked nucleomonomer agent containing chemically modified-siRNA delivery system, were evaluated in mice.

RESULTS

Plasma LBP levels were associated with fat mass and leptin levels in women with obesity, but not in men with obesity. In mice, plasma LBP downregulation led to reduced weight, fat mass and leptin gain after a high-fat and high-sucrose diet (HFHS) in females, in parallel to increased expression of adipogenic and thermogenic genes in visceral adipose tissue. This was not observed in males. Plasma LBP downregulation avoided the increase in serum LPS levels in HFHS-fed male and female mice. Serum LPS levels were positively correlated with body weight and fat mass gain, and negatively with markers of adipose tissue function only in female mice. The sexually dimorphic effects were replicated in mice with established obesity. Of note, LBP downregulation led to recovery of estrogen receptor alpha (Esr1) mRNA levels in females but not in males.

CONCLUSION

LBP seems to exert a negative feedback on ERα-mediated estrogen action, impacting on genes involved in thermogenesis. The known decreased estrogen action and negative effects of metabolic endotoxemia may be targeted through LBP downregulation.

Dietary Protein Restriction Improves Metabolic Dysfunction in Patients with Metabolic Syndrome in a Randomized, Controlled Trial

Dietary restriction (DR) reduces adiposity and improves metabolism in patients with one or more symptoms of metabolic syndrome. Nonetheless, it remains elusive whether the benefits of DR in humans are mediated by calorie or nutrient restriction. This study was conducted to determine whether isocaloric dietary protein restriction is sufficient to confer the beneficial effects of dietary restriction in patients with metabolic syndrome. We performed a prospective, randomized controlled dietary intervention under constant nutritional and medical supervision. Twenty-one individuals diagnosed with metabolic syndrome were randomly assigned for caloric restriction (CR; n = 11, diet of 5941 ± 686 KJ per day) or isocaloric dietary protein restriction (PR; n = 10, diet of 8409 ± 2360 KJ per day) and followed for 27 days. Like CR, PR promoted weight loss due to a reduction in adiposity, which was associated with reductions in blood glucose, lipid levels, and blood pressure. More strikingly, both CR and PR improved insulin sensitivity by 62.3% and 93.2%, respectively, after treatment. Fecal microbiome diversity was not affected by the interventions. Adipose tissue bulk RNA-Seq data revealed minor changes elicited by the interventions. After PR, terms related to leukocyte proliferation were enriched among the upregulated genes. Protein restriction is sufficient to confer almost the same clinical outcomes as calorie restriction without the need for a reduction in calorie intake. The isocaloric characteristic of the PR intervention makes this approach a more attractive and less drastic dietary strategy in clinical settings and has more significant potential to be used as adjuvant therapy for people with metabolic syndrome.

Calorie restriction on normal body weight mice prevents body weight regain on a follow-up high-fat diet by shaping an obesity-resistant-like gut microbiota profile

Calorie restriction (CR) is one of the most common approaches for obesity treatment, but whether resuming ad libitum feeding after CR in normal-weight mice can affect excessive weight regain remains poorly studied. To address this issue, male C57BL/6 mice were placed in three groups: a control group (n = 10), a group fed normal diet with 30% CR (n = 20); and a group fed a HF diet (n = 30). After four weeks, the CR group was fed either a normal diet (NDCR, n = 10) or a high-fat diet (HFCR, n = 10) for an additional eight weeks. At the end of the experiment, mice in the HF group ranked in the upper and lower thirds for weight gain were designated as obesity-prone (HFOP, n = 10) and obesity-resistant (HFOR, n = 10), respectively. CR delayed weight regain and visceral fat accumulation. Gut microbiota in the HFCR group were more similar to the HFOR group than the HFOP group, mainly due to reversion of the decreased level of Clostridiales induced by CR. Mediation analysis showed that Clostridiales may delay body weight regain by affecting the interconversion of succinate and fumarate. Random forest and structural equation analyses showed Christensenellaceae were the most important biomarker for alleviation of obesity. In conclusion, CR shapes an obesity-resistant-like gut microbiota profile that may attenuate body weight regain.

The Function and the Affecting Factors of the Zebrafish Gut Microbiota

Gut microbiota has become a topical issue in unraveling the research mechanisms underlying disease onset and progression. As an important and potential "organ," gut microbiota plays an important role in regulating intestinal epithelial cell differentiation, proliferation, metabolic function and immune response, angiogenesis and host growth. More recently, zebrafish models have been used to study the interactions between gut microbiota and hosts. It has several advantages, such as short reproductive cycle, low rearing cost, transparent larvae, high genomic similarity to humans, and easy construction of germ-free (GF) and transgenic zebrafish. In our review, we reviewed a large amount of data focusing on the close relationship between gut microbiota and host health. Moreover, we outlined the functions of gut microbiota in regulating intestinal epithelial cell differentiation, intestinal epithelial cell proliferation, metabolic function, and immune response. More, we summarized major factors that can influence the composition, abundance, and diversity of gut microbiota, which will help us to understand the significance of gut microbiota in regulating host biological functions and provide options for maintaining the balance of host health.

Obese Individuals With and Without Phlegm-Dampness Constitution Show Different Gut Microbial Composition Associated With Risk of Metabolic Disorders

Background

Obesity is conventionally considered a risk factor for multiple metabolic diseases, such as dyslipidemia, type 2 diabetes, hypertension, and cardiovascular disease (CVD). However, not every obese patient will progress to metabolic disease. Phlegm-dampness constitution (PDC), one of the nine TCM constitutions, is considered a high-risk factor for obesity and its complications. Alterations in the gut microbiota have been shown to drive the development and progression of obesity and metabolic disease, however, key microbial changes in obese patients with PDC have a higher risk for metabolic disorders remain elusive.

Methods

We carried out fecal 16S rRNA gene sequencing in the present study, including 30 obese subjects with PDC (PDC), 30 individuals without PDC (non-PDC), and 30 healthy controls with balanced constitution (BC). Metagenomic functional prediction of bacterial taxa was achieved using PICRUSt.

Results

Obese individuals with PDC had higher BMI, waist circumference, hip circumference, and altered composition of their gut microbiota compared to non-PDC obese individuals. At the phylum level, the gut microbiota was characterized by increased abundance of Bacteroidetes and decreased levels of Firmicutes and Firmicutes/Bacteroidetes ratio. At the genus level, Faecalibacterium, producing short-chain fatty acid, achieving anti-inflammatory effects and strengthening intestinal barrier functions, was depleted in the PDC group, instead, Prevotella was enriched. Most PDC-associated bacteria had a stronger correlation with clinical indicators of metabolic disorders rather than more severe obesity. The PICRUSt analysis demonstrated 70 significantly different microbiome community functions between the two groups, which were mainly involved in carbohydrate and amino acid metabolism, such as promoting Arachidonic acid metabolism, mineral absorption, and Lipopolysaccharide biosynthesis, reducing Arginine and proline metabolism, flavone and flavonol biosynthesis, Glycolysis/Gluconeogenesis, and primary bile acid biosynthesis. Furthermore, a disease classifier based on microbiota was constructed to accurately discriminate PDC individuals from all obese people.

Conclusion

Our study shows that obese individuals with PDC can be distinguished from non-PDC obese individuals based on gut microbial characteristics. The composition of the gut microbiome altered in obese with PDC may be responsible for their high risk of metabolic diseases.

Multi-omics analysis reveals gut microbiota-induced intramuscular fat deposition via regulating expression of lipogenesis-associated genes

The gut microbiome has great effects on the digestion, absorption, and metabolism of lipids. However, the microbiota composition that can alter the fat deposition and the meat quality of pigs remains unclear. Here, we used Laiwu (LW) pigs (a native Chinese breed with higher intramuscular fat) compared with commercial crossbreed Duroc × (Landrace × Yorkshire) (DLY) pigs to investigate the effects of microbiota on meat quality, especially in intramuscular fat content. A total of 32 DLY piglets were randomly allotted to 4 groups and transplanted with fecal microbiota from healthy LW pigs. The results indicated that the high dose of fecal microbiota transplantation (HFMT) selectively enhanced fat deposition in longissimus dorsi (P < 0.05) but decreased backfat thickness (P < 0.05) compared with control group. HFMT significantly altered meat color and increased feed conversation ratio (P < 0.05). Furthermore, the multi-omics analysis revealed that Bacteroides uniformis, Sphaerochaeta globosa, Hydrogenoanaerobacterium saccharovorans, and Pyramidobacter piscolens are the core species which can regulate lipid deposition. A total of 140 male SPF C57BL/6j mice were randomly allotted into 7 groups and administrated with these 4 microbes alone or consortium to validate the relationships between microbiota and lipid deposition. Inoculating the bacterial consortium into mice increased intramuscular fat content (P < 0.05) compared with control mice. Increased expressions of lipogenesis-associated genes including cluster of differentiation 36 (Cd36), diacylglycerol O-acyltransferase 2 (Dgat2), and fatty acid synthase (FASN) were observed in skeletal muscle in the mice with mixed bacteria compared with control mice. Together, our results suggest that the gut microbiota may play an important role in regulating the lipid deposition in the muscle of pigs and mice.