Conserved shifts in the gut microbiota due to gastric bypass reduce host weight and adiposity

Gut microbiota alterations induced by Roux-en-Y gastric bypass result in glucose-lowering by enhancing intestinal glucose excretion

Roux-en-Y gastric bypass (RYGB) results in glucose-lowering in patients with type 2 diabetes mellitus (T2DM) and may be associated with increased intestinal glucose excretion. However, the contribution of intestinal glucose excretion to glycemic control after RYGB and its underlying mechanisms are not fully elucidated. Here, we confirmed that intestinal glucose excretion significantly increased in obese rats after RYGB, which was negatively correlated with postoperative blood glucose levels. Moreover, we also found that the contribution of Biliopancreatic limb length, an important factor affecting glycemic control after RYGB, to the improvement of glucose metabolism after RYGB attributed to the enhancement of intestinal glucose excretion. Subsequently, we further determined through multiple animal models that intestinal glucose excretion is physiological rather than pathological and plays a crucial role in maintaining glucose homeostasis in the body. Finally, we employed germ-free mice colonized with fecal samples from patients and rats to demonstrate that enhanced intestinal glucose excretion after RYGB is directly modulated by the surgery-induced changes in the gut microbiota. These results indicated that the gut microbiota plays a direct causal role in the hypoglycemic effect of RYGB by promoting intestinal glucose excretion, which may provide new insights for developing gut microbiota-based therapies for T2DM.

A Western-Style Diet Influences Ingestive Behavior and Glycemic Control in a Rat Model of Roux-en-Y Gastric Bypass Surgery

Background: Roux-en-Y gastric bypass (RYGB) surgery results in weight reduction and decreased energy intake and can ameliorate type 2 diabetes. These beneficial effects are usually attributed to changes in hunger and satiety and relatively rapid improvements in glycemic control, but these effects may depend on dietary adherence. The aim of this study is to investigate the relatively early effects of RYGB surgery on weight reduction (by focusing on eating patterns) and glycemic control in rats subjected to a healthy maintenance diet or an unhealthy Western-style diet. Methods: Rats were fed a high-fat diet with added sucrose (HF/S) or a low-fat (LF) diet. Body weight, high-resolution tracking of meal-related parameters, and glucose regulation after overnight fasting and during a mixed meal tolerance test (MMTT; 2 mL sweet/condensed milk) were measured before and after RYGB (RYGB+) or sham surgery (RYGB-). Results: HF/S feeding led to an increased body weight just before RYGB surgery, but it also caused enhanced weight loss following RYGB, which led to similar body weights in the HF/S and LF diet groups twenty-four days post-operatively. RYGB surgery and diet dependently and independently influenced meal-related parameter outcomes, where both RYGB+ and HF/S feeding resulted in shorter meal duration (p < 0.01), higher ingestion rates (p < 0.001), and increased satiety ratio (p < 0.05), especially in the HF/S diet group subjected to RYGB. While RYGB surgery generally improved baseline glycemic parameters including HOMA-IR (p < 0.01), it often interacted with diet to affect MMTT-induced hyperglycemia (p < 0.05), beta-cell sensitivity (p < 0.01), and the insulinogenic index (p < 0.01), with the LF rats overall maintaining better glycemic control than the HF/S-fed rats. Conclusions: This study shows the importance of controlling diet after RYGB surgery, as diet type significantly influences ingestive behavior, post-prandial glucose regulation, beta-cell sensitivity, and glucose tolerance after RYGB.

A multi-omics microbiome signature is associated with the benefits of gastric bypass surgery and is differentiated from diet induced weight loss through 2 years of follow-up

Roux-en-Y gastric bypass (GBP) surgery is an effective treatment for reducing body weight and correcting metabolic dysfunction in individuals with severe obesity. Herein, we characterize the differences between very low energy diet (VLED) and GBP induced weight loss by multi-omic analyses of microbiome and host features in a non-randomized, controlled, single-center study. Eighty-eight participants with severe obesity were recruited into two arms - GBP versus VLED with matching weight loss for 6 weeks and 2-years of follow-up. A dramatic shift in the distribution of gut microbial taxa and their functional capacity was seen in the GBP group at Week 2 after surgery and was sustained through 2 years. Multi-omic analyses were performed after 6 weeks of matching weight loss between the GBP and VLED groups, which pointed to microbiome derived metabolites such as indoxyl sulphate as characterizing the GBP group. We also identified an inverse association between Streptococcus parasanguinis (an oral commensal) and plasma levels of tryptophan and tyrosine. These data have important implications, as they reveal a significant robust restructuring of the microbiome away from a baseline dysbiotic state in the GBP group. Furthermore, multi-omics modelling points to potentially novel mechanistic insights at the intersection of the microbiome and host.

Exploring the Potential of Dietary Supplements to Alleviate Pain Due to Long COVID

Long COVID, characterized by persistent symptoms following COVID-19 infection, significantly impacts individuals' health and daily functioning due to fatigue and pain. Focusing on pain, this review addresses nociplastic and chronic pain conditions. Interventions designed to reduce inflammation, oxidative stress, and enhance vagal activity may offer a promising approach to managing post-pandemic pain. This review presents individual components of food supplements with demonstrated efficacy in one or more pain conditions, focusing on their proposed mechanisms and clinical activity in pain, including their use in post-COVID-19 pain when available. Many of these substances have a long history of safe use and may offer an alternative to long-term analgesic drug treatment, which is often associated with potential side effects. This review also explores the potential for synergistic effects when combining these substances with each other or with conventional analgesics, considering the advantages for both patients and the healthcare system in using these substances as adjunctive or primary therapies for pain symptoms related to long COVID. While preclinical scientific literature provides a mechanistic basis for the action of several food supplements on pain control mechanisms and signaling pathways, clinical experience, particularly in the field of long COVID-associated pain, is still limited. However, the reviewed literature strongly suggests that the use of food supplements in long COVID-associated pain is an attainable goal, provided that rigorous clinical trials are conducted.

Oral microbiome changes in subjects with obesity following bariatric surgery compared to lean counterparts

Introduction

This study aimed to compare oral microbiome profiles between obese and lean individuals without clinical periodontitis, and to assess changes in the oral microbiome of obese subjects following bariatric surgery.

Methods

Individuals with a body mass index (BMI) > 30 were enrolled in the obese group, whereas those with a BMI < 23 served as controls. The obese surgery group, which consented to bariatric surgery, was followed up at 1, 3, and 6 months with clinical examinations. Oral examinations were conducted and periodontal disease was classified based on probing results. Saliva, buccal and subgingival microbiome samples were analyzed for community diversity, relative bacterial abundance, and differential abundance between control (n = 24) and obese group (n = 31). To evaluate effect size and statistical power, we used micropower, a simulation-based method for Permutational Multivariate Analysis of Variance-based β-diversity comparisons.

Results

The obese group exhibited distinct alpha diversity (buccal: Chao1 p = 0.0002, Shannon p = 0.0003, supragingival: Shannon p < 0.0001) compared with the control group. Bray-Curtis distance analysis indicated significant disparities in microbiome composition distribution in saliva (p = 0.003), buccal (p = 0.002), and subgingival plaque samples (p = 0.001). Although the obese and normal weight groups exhibited no significant periodontal differences, the obese group showed distinct species associated with periodontal disease, especially in subgingival plaque including Filifactor alocis, Peptostreptococcaceae spp., Prevotella spp., and Treponema maltophilum. Cluster analysis of the obese surgery group indicated the emergence of microbiomes associated with a healthy state that increased over time including Streptococcus salivarious and various Veillonella spp., whereas clusters containing periodontal pathogens including Porphyromonas spp., tended to diminish.

Discussion

The oral microbiome at 6 months post-bariatric surgery indicates a potential shift toward a healthy periodontal state, suggesting that weight loss interventions may positively impact oral microbial communities even in the absence of clinical periodontitis.

Disinfection by-products of metformin in the environment: A systematic toxicity evaluation on gut-liver-brain axis homeostasis and establishment of a detection method based on NiFe-LDOs/N-BC composite

Metformin, a first-line drug used to treat type 2 diabetes, is not metabolised in the body and discharged into the environment in the form of prototype drugs. Compounds C (C4H6ClN3) and Y (C4H6ClN5) are the main disinfection byproducts of metformin in urban sewage treatment; however, their potential toxicity is unclear. In this study, absorption, distribution, metabolism, elimination, and toxicity (ADMET) prediction indicated that compounds C and Y had potential hepatotoxicity and could cross the blood-brain-barrier. Toxicity verification tests indicated a sex difference in the acute toxicity of compound C, with an LD50 value of 253.269 mg kg-1 for male mice and 728.908 mg kg-1 for female mice. The subacute toxicity of compounds C and Y was evaluated to study the toxicity mechanism via the gut-liver-brain axis, which indicated that they could cause damage to the liver and brain, change the composition of the gut microbiota, and disturb the levels of metabolites in mice. Neuron-like magnetic N-doped biochar (NiFe-LDOs/N-BC) was synthesised using hydrothermal and calcination methods, and the optimised d-MSPE-HPLC-UV method was proven to be applicable for the trace detection of compound C in real water samples. The simultaneous presentation of toxicity evaluation and trace detection of compound C is intended to make the monitoring system for compound C more comprehensive.

A menu for microbes: unraveling appetite regulation and weight dynamics through the microbiota-brain connection across the lifespan

Appetite, as the internal drive for food intake, is often dysregulated in a broad spectrum of conditions associated with over- and under-nutrition across the lifespan. Appetite regulation is a complex, integrative process comprising psychological and behavioral events, peripheral and metabolic inputs, and central neurotransmitter and metabolic interactions. The microbiota-gut-brain axis has emerged as a critical mediator of multiple physiological processes, including energy metabolism, brain function, and behavior. Therefore, the role of the microbiota-gut-brain axis in appetite and obesity is receiving increased attention. Omics approaches such as genomics, epigenomics, transcriptomics, proteomics, and metabolomics in appetite and weight regulation offer new opportunities for featuring obesity phenotypes. Furthermore, gut-microbiota-targeted approaches such as pre-, pro-, post-, and synbiotic, personalized nutrition, and fecal microbiota transplantation are novel avenues for precision treatments. The aim of this narrative review is 1) to provide an overview of the role of the microbiota-gut-brain axis in appetite regulation across the lifespan and 2) to discuss the potential of omics and gut microbiota-targeted approaches to deepen understanding of appetite regulation and obesity.

Roux-en-Y gastric bypass-associated fecal tyramine promotes colon cancer risk via increased DNA damage, cell proliferation, and inflammation

BACKGROUND

Fecal abundances of Enterobacteriaceae and Enterococcaceae are elevated in patients following Roux-en-Y gastric bypass (RYGB) surgery. Concurrently, fecal concentrations of tyramine, derived from gut bacterial metabolism of tyrosine and/or food, increased post-RYGB. Furthermore, emerging evidence suggests that RYGB is associated with increased colorectal cancer (CRC) risk. However, the causal link between RYGB-associated microbial metabolites and CRC risk remains unclear. Hence, this study investigated the tyrosine metabolism of Enterobacteriaceae and Enterococcaceae strains isolated from patients post-RYGB and explored the causal effects of tyramine on the CRC risk and tumorigenesis using both human colonic cancer cell line (HCT 116) and wild-type and ApcMin/+ mice.

RESULTS

We isolated 31 bacterial isolates belonging to Enterobacteriaceae and Enterococcaceae families from the feces of patients with RYGB surgery. By culturing the isolates in tyrosine-supplemented medium, we found that Citrobacter produced phenol as a main product of tyrosine, whereas Enterobacter and Klebsiella produced 4-hydroxyphenylacetate, Escherichia produced 4-hydroxyphenyllactate and 4-hydroxyphenylpyruvate, and Enterococcus and two Klebsiella isolates produced tyramine. These observations suggested the gut bacterial contribution to increased fecal concentrations of tyramine post-RYGB. We subsequently evaluated the impact of tyramine on CRC risk and development. Tyramine induced necrosis and promoted cell proliferation and DNA damage of HCT 116 cells. Daily oral administration of tyramine for 49 days to wild-type mice resulted in visible adenomas in 5 out of 12 mice, accompanied by significantly enhanced DNA damage (γH2AX +) and an increased trend of cell proliferation (Ki67 +) in the ileum, along with an upregulated expression of the cell division cycle gene (Cdc34b) in the colon. To evaluate the impact of tyramine on intestinal tumor growth, we treated ApcMin/+ mice with the same doses of tyramine and duration. These mice showed larger colonic tumor size and increased intestinal cell proliferation and inflammation (e.g., increased mRNA expression of IL-17A and higher number of Ly6G + neutrophils) compared to water-treated ApcMin/+ control mice.

CONCLUSIONS

Our results collectively suggested that RYGB-associated fecal bacteria could contribute to tyramine production and tyramine increased CRC risk by increasing DNA damage, cell proliferation, and pro-inflammatory responses of the gut. Monitoring and modulating tyramine concentrations in high-risk individuals could aid CRC prognosis and management. Video Abstract.

Beyond weight loss: exploring the neurological ramifications of altered gut microbiota post-bariatric surgery

This review discusses findings related to neurological disorders, gut microbiota, and bariatric surgery, focusing on neurotransmitters, neuroendocrine, the pathophysiology of bacteria contributing to disorders, and possible therapeutic interventions. Research on neurotransmitters suggests that their levels are heavily influenced by gut microbiota, which may link them to neurological disorders such as Alzheimer's disease, Parkinson's disease, Multiple sclerosis, Depression, and Autism spectrum disorder. The pathophysiology of bacteria that reach and influence the central nervous system has been documented. Trends in microbiota are often observed in specific neurological disorders, with a prominence of pro-inflammatory bacteria and a reduction in anti-inflammatory types. Furthermore, bariatric surgery has been shown to alter microbiota profiles similar to those observed in neurological disorders. Therapeutic interventions, including fecal microbiota transplants and probiotics, have shown potential to alleviate neurological symptoms. We suggest a framework for future studies that integrates knowledge from diverse research areas, employs rigorous methodologies, and includes long-trial clinical control groups.

Is the Microbiome Enough: Role of Diet and Metabolites in Our Interventions

The gut microbiome may represent a new pillar in human health. As we move beyond the small data sets used for comparison, we will need to consider the bidirectional implications of interactions between diet/lifestyle (inputs) and metabolites (outputs) in interventional clinical trials to maximize the beneficial impact in health and disease.

Health Effects and Therapeutic Potential of the Gut Microbe Akkermansia muciniphila

Akkermansia muciniphila is a bacterium commonly found in the human gastrointestinal tract that has received considerable interest as a potential probiotic for the improvement of gut health and overall metabolic function. A. muciniphila is enriched in the mucus layer of the intestinal lining, where it degrades mucin and plays a significant role in gut barrier maintenance and immune regulation. A higher abundance of A. muciniphila has been observed in the gut of healthy individuals relative to those with metabolic disorders, and multiple metabolic benefits, including improved glucose management, reduced body fat, and reduced inflammation have been linked to A. muciniphila. Current research on A. muciniphila primarily relies on mouse models, with limited human interventional studies available. While these animal studies offer valuable insights into the potential roles of A. muciniphila in health and disease, further clinical investigations in humans are needed to fully understand its impact. Here, we explore the current scope of A. muciniphila research and its potential as a therapeutic agent to improve gut and metabolic health while also emphasizing the need to optimize techniques to further improve studies of this organism.

Multiomics of the intestine-liver-adipose axis in multiple studies unveils a consistent link of the gut microbiota and the antiviral response with systemic glucose metabolism

BACKGROUND

The microbiota is emerging as a key factor in the predisposition to insulin resistance and obesity.

OBJECTIVE

To understand the interplay among gut microbiota and insulin sensitivity in multiple tissues.

DESIGN

Integrative multiomics and multitissue approach across six studies, combining euglycaemic clamp measurements (used in four of the six studies) with other measurements of glucose metabolism and insulin resistance (glycated haemoglobin (HbA1c) and fasting glucose).

RESULTS

Several genera and species from the Proteobacteria phylum were consistently negatively associated with insulin sensitivity in four studies (ADIPOINST, n=15; IRONMET, n=121, FLORINASH, n=67 and FLOROMIDIA, n=24). Transcriptomic analysis of the jejunum, ileum and colon revealed T cell-related signatures positively linked to insulin sensitivity. Proteobacteria in the ileum and colon were positively associated with HbA1c but negatively with the number of T cells. Jejunal deoxycholic acid was negatively associated with insulin sensitivity. Transcriptomics of subcutaneous adipose tissue (ADIPOMIT, n=740) and visceral adipose tissue (VAT) (ADIPOINST, n=29) revealed T cell-related signatures linked to HbA1c and insulin sensitivity, respectively. VAT Proteobacteria were negatively associated with insulin sensitivity. Multiomics and multitissue integration in the ADIPOINST and FLORINASH studies linked faecal Proteobacteria with jejunal and liver deoxycholic acid, as well as jejunal, VAT and liver transcriptomic signatures involved in the actin cytoskeleton, insulin and T cell signalling. Fasting glucose was consistently linked to interferon-induced genes and antiviral responses in the intestine and VAT. Studies in Drosophila melanogaster validated these human insulin sensitivity-associated changes.

CONCLUSION

These data provide comprehensive insights into the microbiome-gut-adipose-liver axis and its impact on systemic insulin action, suggesting potential therapeutic targets.Cite Now.

Intestinal rearrangement of biliopancreatic limbs, alimentary limbs, and common limbs in obese type 2 diabetic mice after duodenal jejunal bypass surgery

Bariatric surgery is an effective treatment for type 2 Diabetes Mellitus (T2DM), yet the precise mechanisms underlying its effectiveness remain incompletely understood. While previous research has emphasized the role of rearrangement of the gastrointestinal anatomy, gaps persist regarding the specific impact on the gut microbiota and barriers within the biliopancreatic, alimentary, and common limbs. This study aimed to investigate the effects of duodenal-jejunal bypass (DJB) surgery on obese T2DM mice. We performed DJB and SHAM surgery in obese T2DM mice to investigate changes in the gut microbiota and barrier across different intestinal limbs. The effects on serum metabolism and potential associations with T2DM improvement were also investigated. Following DJB surgery, there was an increased abundance of commensals across various limbs. Additionally, the surgery improved intestinal permeability and inflammation in the alimentary and common limbs, while reducing inflammation in the biliopancreatic limbs. Furthermore, DJB surgery also improved T2DM by increasing L-glutamine, short-chain fatty acids, and bile acids and decreasing branched-chain amino acids. This study underscores the role of intestinal rearrangement in reshaping gut microbiota composition and enhancing gut barrier function, thereby contributing to the amelioration of T2DM following bariatric surgery, and providing new insights for further research on bariatric surgery.

A Longer Biliopancreatic Limb and Shorter Common Channel Enhance Weight Loss But May Have Harmful Effects in Mouse Models of Roux-en-Y Gastric Bypass

BACKGROUND

RYGB consists of the Roux limb (RL), the biliopancreatic limb (BPL), and the common channel (CC). There is no consensus on the optimal limb lengths.

METHODS

Using a mouse model of RYGB, 30 diet-induced obese mice were divided into two groups with varying BPL and CC lengths: a standard BPL with a long CC (RYGB S) and a long BPL with a short CC (RYGB L). Additionally, 9 age-matched, lean control mice (LC) were also included in this study.

RESULTS

RYGB S had limb lengths of RL = 17%, BPL = 24%, and CC = 59%. RYGB L had limb lengths of RL = 17%, BPL = 32%, and CC = 51%. RYGB S and RYGB L had 67% and 40% survival, respectively. Mortality in RYGB L included more instances where the cause of death was not apparent. RYGB L demonstrated greater weight loss, lower energy expenditure, and lower heart mass as compared to RYGB S. Both RYGB groups had lower epidydimal fat mass, spleen mass, and bone mineral density compared to LC. RYGB L had a lower heart mass than RYGB S and LC. While the relative abundance of Eubacterium was lower in RYGB L than in RYGB S, no other gut microbiota differences were observed.

CONCLUSIONS

A longer BPL with a shorter CC induces greater weight loss but may lead to adverse effects, including lower heart mass, reduced bone density, and deaths with unclear causes.

The 5-HT-related gut-brain axis in obesity

AIMS

The incidence of obesity increases annually. It is closely related to the occurrence of cardiovascular diseases, malignant tumors, etc., and has become a major global health problem. 5-hydroxytryptamine (5-HT), a multifunctional monoamine neurotransmitter, is dispersed throughout the central nervous system and digestive tract. It is intimately related to the mechanism of obesity.

MATERIALS AND METHODS

PubMed, Web of Science and Embase were carefully searched. We collected articles that are closely related to 5-HT, the gut-brain axis, and obesity.

KEY FINGDINGS

The gut microbiota not only influences nutrient metabolism but also centrally meditates appetite and mood regulation. The gut-brain axis, a system connecting the gut and the brain, is known to participate in two-way communication between the gut flora and the central nervous system.

SIGNIFICANCE

There have been few reports on whether peripheral and central 5-HT interact bidirectionally via the gut-brain axis and jointly play a role in the pathogenesis of obesity. In this review, we summarize the rationale for the contribution of the 5-HT-related gut-brain axis to the development of obesity and explore feasible signaling pathways, which elucidates new targets for preventing and treating obesity.

The Role of Gut Microbiota in the Onset and Progression of Obesity and Associated Comorbidities

Obesity, a global public health problem, is constantly increasing, so the concerns in preventing and combating it are increasingly focused on the intestinal microbiota. It was found that the microbiota is different in lean people compared to obese individuals, but the exact mechanisms by which energy homeostasis is influenced are still incompletely known. Numerous studies show the involvement of certain bacterial species in promoting obesity and associated diseases such as diabetes, hypertension, cancer, etc. Our aim is to summarize the main findings regarding the influence of several factors such as lifestyle changes, including diet and bariatric surgery, on the diversity of the gut microbiota in obese individuals. The second purpose of this paper is to investigate the potential effect of various microbiota modulation techniques on ameliorating obesity and its comorbidities. A literature search was conducted using the PubMed database, identifying articles published between 2019 and 2024. Most studies identified suggest that obesity is generally associated with alterations of the gut microbiome such as decreased microbial diversity, an increased Firmicutes-to-Bacteroidetes ratio, and increased SCFAs levels. Our findings also indicate that gut microbiota modulation techniques could represent a novel strategy in treating obesity and related metabolic diseases. Although some mechanisms (e.g., inflammation or hormonal regulation) are already considered a powerful connection between gut microbiota and obesity development, further research is needed to enhance the knowledge on this particular topic.

Characterization of gut microbiota dynamics in an Alzheimer's disease mouse model through clade-specific marker-based analysis of shotgun metagenomic data

Alzheimer's disease (AD) is a complex neurodegenerative disorder significantly impairing cognitive faculties, memory, and physical abilities. To characterize the modulation of the gut microbiota in an in vivo AD model, we performed shotgun metagenomics sequencing on 3xTgAD mice at key time points (i.e., 2, 6, and 12 months) of AD progression. Fecal samples from both 3xTgAD and wild-type mice were collected, DNA extracted, and sequenced. Quantitative taxon abundance assessment using MetaPhlAn 4 ensured precise microbial community representation. The analysis focused on species-level genome bins (SGBs) including both known and unknown SGBs (kSGBs and uSGBs, respectively) and also comprised higher taxonomic categories such as family-level genome bins (FGBs), class-level genome bins (CGBs), and order-level genome bins (OGBs). Our bioinformatic results pinpointed the presence of extensive gut microbial diversity in AD mice and showed that the largest proportion of AD- and aging-associated microbiome changes in 3xTgAD mice concern SGBs that belong to the Bacteroidota and Firmicutes phyla, along with a large set of uncharacterized SGBs. Our findings emphasize the need for further advanced bioinformatic studies for accurate classification and functional analysis of these elusive microbial species in relation to their potential bridging role in the gut-brain axis and AD pathogenesis.

Effects of environmentally relevant concentrations of florfenicol on the glucose metabolism system, intestinal microbiome, and liver metabolome of zebrafish

Florfenicol, a widely used veterinary antibiotic, has now been frequently detected in various water environments and human urines, with high concentrations. Accordingly, the ecological risks and health hazards of florfenicol are attracting increasing attention. In recent years, antibiotic exposure has been implicated in the disruption of animal glucose metabolism. However, the specific effects of florfenicol on the glucose metabolism system and the underlying mechanisms are largely unknown. Herein, zebrafish as an animal model were exposed to environmentally relevant concentrations of florfenicol for 28 days. Using biochemical and molecular analyses, we found that exposure to florfenicol disturbed glucose homeostasis, as evidenced by the abnormal levels of blood glucose and hepatic/muscular glycogen, and the altered expression of genes involved in glycogenolysis, gluconeogenesis, glycogenesis, and glycolysis. Considering the efficient antibacterial activity of florfenicol and the crucial role of intestinal flora in host glucose metabolism, we then analyzed changes in the gut microbiome and its key metabolite short-chain fatty acids (SCFAs). Results indicated that exposure to florfenicol caused gut microbiota dysbiosis, inhibited the production of intestinal SCFAs, and ultimately affected the downstream signaling pathways of SCFA involved in glucose metabolism. Moreover, non-targeted metabolomics revealed that arachidonic acid and linoleic acid metabolic pathways may be associated with insulin sensitivity changes in florfenicol-exposed livers. Overall, this study highlighted a crucial aspect of the environmental risks of florfenicol to both non-target organisms and humans, and presented novel insights into the mechanistic elucidation of metabolic toxicity of antibiotics.

Incretin hormones, obesity and gut microbiota

Over the past 40 years, the prevalence of obesity has risen dramatically, reaching epidemic proportions. By 2030 the number of people affected by obesity will reach 1.12 billion worldwide. Gastrointestinal hormones, namely incretins, play a vital role in the pathogenesis of obesity and its comorbidities. GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1), which are secreted from the intestine after nutrient intake and stimulate insulin secretion from pancreatic β cells, influence lipid metabolism, gastric empting, appetite and body weight. The gut microbiota plays an important role in various metabolic conditions, including obesity and type 2 diabetes and influences host metabolism through the interaction with enteroendocrine cells that modulate incretins secretion. Gut microbiota metabolites, such as short-chain fatty acids (SCFAs) and indole, directly stimulate the release of incretins from colonic enteroendocrine cells influencing host satiety and food intake. Moreover, bariatric surgery and incretin-based therapies are associated with increase gut bacterial richness and diversity. Understanding the role of incretins, gut microbiota, and their metabolites in regulating metabolic processes is crucial to develop effective strategies for the management of obesity and its associated comorbidities.

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.

Free Fatty Acids and Free Fatty Acid Receptors: Role in Regulating Arterial Function

The metabolic network's primary sources of free fatty acids (FFAs) are long- and medium-chain fatty acids of triglyceride origin and short-chain fatty acids produced by intestinal microorganisms through dietary fibre fermentation. Recent studies have demonstrated that FFAs not only serve as an energy source for the body's metabolism but also participate in regulating arterial function. Excess FFAs have been shown to lead to endothelial dysfunction, vascular hypertrophy, and vessel wall stiffness, which are important triggers of arterial hypertension and atherosclerosis. Nevertheless, free fatty acid receptors (FFARs) are involved in the regulation of arterial functions, including the proliferation, differentiation, migration, apoptosis, inflammation, and angiogenesis of vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs). They actively regulate hypertension, endothelial dysfunction, and atherosclerosis. The objective of this review is to examine the roles and heterogeneity of FFAs and FFARs in the regulation of arterial function, with a view to identifying the points of intersection between their actions and providing new insights into the prevention and treatment of diseases associated with arterial dysfunction, as well as the development of targeted drugs.

Urolithin B protects mice from diet-induced obesity, insulin resistance, and intestinal inflammation by regulating gut microbiota composition

The increasing prevalence of obesity and type 2 diabetes (T2D) signifies the failure of conventional treatments for these diseases. The gut microbiota has been proposed as a key player in the pathophysiology of diet-induced T2D. Urolithin B (Uro B), a gut microbiota-derived polyphenol metabolite, exerts several beneficial health effects. In this study, we investigated the metabolic effects of Uro B on high-fat/high-sucrose (HFHS)-fed mice and determined whether its antidiabetic effects are related to the modulation of the gut microbiota. C57BL/6J mice were fed either a chow or HFHS diet. HFHS-fed mice were administered daily with either a vehicle (water) or different doses of Uro B (100 or 200 mg kg-1) for eight weeks. The composition of the gut microbiota was assessed by 16S rRNA sequencing. The results showed that Uro B treatment reduced HFHS-induced weight gain and visceral obesity and decreased liver weight and triglyceride accumulation associated with blunted hepatic oxidative stress and inflammation. Furthermore, Uro B administration improved insulin sensitivity as revealed by improved insulin tolerance, a lower homeostasis model assessment of insulin resistance, and decreased glucose-induced hyperinsulinemia during the oral glucose tolerance test. Uro B treatment was found to lower the intestinal triglyceride content and alleviate intestinal inflammation and oxidative stress. Remarkably, Uro B treatment markedly increased the proportion of the mucin-degrading bacterium Akkermansia in metagenomic samples. In conclusion, Uro B exerts beneficial metabolic effects by alleviating HFHS diet-induced features of metabolic syndrome, which is associated with a proportional increase in the population of Akkermansia spp.

Vertical Sleeve Gastrectomy Reduces Gut Luminal Deoxycholic Acid Concentrations in Mice

BACKGROUND

Bariatric surgery alters bile acid metabolism, which contributes to post-operative improvements in metabolic health. However, the mechanisms by which bariatric surgery alters bile acid metabolism are incompletely defined. In particular, the role of the gut microbiome in the effects of bariatric surgery on bile acid metabolism is incompletely understood. Therefore, we sought to define the changes in gut luminal bile acid composition after vertical sleeve gastrectomy (VSG).

METHODS

Bile acid profile was determined by UPLC-MS/MS in serum and gut luminal samples from VSG and sham-operated mice. Sham-operated mice were divided into two groups: one was fed ad libitum, while the other was food-restricted to match their body weight to the VSG-operated mice.

RESULTS

VSG decreased gut luminal secondary bile acids, which was driven by a decrease in gut luminal deoxycholic acid concentrations and abundance. However, gut luminal cholic acid (precursor for deoxycholic acid) concentration and abundance did not differ between groups. Therefore, the observed decrease in gut luminal deoxycholic acid abundance after VSG was not due to a reduction in substrate availability.

CONCLUSION

VSG decreased gut luminal deoxycholic acid abundance independently of body weight, which may be driven by a decrease in gut bacterial bile acid metabolism.

The long-term effect of bariatric/metabolic surgery versus pharmacologic therapy in type 2 diabetes mellitus patients: A systematic review and meta-analysis

Metabolic/bariatric surgery as a treatment for obesity and related diseases, such as type 2 diabetes mellitus (T2DM), has been increasingly recognised in recent years. However, compared with conventional pharmacologic therapy, the long-term effect (≥ 5 years) of metabolic surgery in T2DM patients is still unclear. This study aimed to evaluate the diabetes remission rate, incidence of diabetic microvascular complications, incidence of macrovascular complications, and mortality in T2DM patients who received metabolic surgery versus pharmacologic therapy more than 5 years after the surgery. Searching the database, including PubMed, Embase, Web of Science, and Cochrane Library from the inception to recent (2024), for randomised clinical trials (RCTs) or cohort studies comparing T2DM patients treated with metabolic surgery versus pharmacologic therapy reporting on the outcomes of the diabetes remission rate, diabetic microvascular complications, macrovascular complications, or mortality over 5 years or more. A total of 15 articles with a total of 85,473 patients with T2DM were eligible for review and meta-analysis in this study. There is a significant long-term increase in diabetes remission for metabolic surgery compared with conventional medical therapy in the overall pooled estimation and RCT studies or cohort studies separately (overall: OR = 4.58, 95% CI: 1.89-11.07, P < 0.001). Significant long-term decreases were found in the pooled results of microvascular complications incidence (HR = 0.57, 95% CI: 0.41-0.78, P < 0.001), macrovascular complications incidence (HR = 0.59, 95% CI: 0.50-0.70, P < 0.001) and mortality (HR = 0.53, 95% CI: 0.53-0.79, P = 0.0018). Metabolic surgery showed more significant long-term effects than pharmacologic therapy on diabetes remission, macrovascular complications, microvascular complications incidence, and all-cause mortality in patients with T2DM using currently available evidence. More high-quality evidence is needed to validate the long-term effects of metabolic surgery versus conventional treatment in diabetes management.

Immune response to post-translationally modified proteins in rheumatoid arthritis: what makes it special?

Rheumatoid arthritis (RA) exhibits common characteristics with numerous other autoimmune diseases, including the presence of susceptibility genes and the presence of disease-specific autoantibodies. Anti-citrullinated protein antibodies (ACPA) are the hallmarking autoantibodies in RA and the anti-citrullinated protein immune response has been implicated in disease pathogenesis. Insight into the immunological pathways leading to anti-citrullinated protein immunity will not only aid understanding of RA pathogenesis, but may also contribute to elucidation of similar mechanisms in other autoantibody-positive autoimmune diseases. Similarly, lessons learnt in other human autoimmune diseases might be relevant to understand potential drivers of RA. In this review, we will summarise several novel insights into the biology of the anti-citrullinated protein response and their clinical associations that have been obtained in recent years. These insights include the identification of glycans in the variable domain of ACPA, the realisation that ACPA are polyreactive towards other post-translational modifications on proteins, as well as new awareness of the contributing role of mucosal sites to the development of the ACPA response. These findings will be mirrored to emerging concepts obtained in other human (autoimmune) disease characterised by disease-specific autoantibodies. Together with an updated understanding of genetic and environmental risk factors and fresh perspectives on how the microbiome could contribute to antibody formation, these advancements coalesce to a progressively clearer picture of the B cell reaction to modified antigens in the progression of RA.

The synergism of Lactobacillaceae, inulin, polyglucose, and aerobic exercise ameliorates hyperglycemia by modulating the gut microbiota community and the metabolic profiles in db/db mice

This study aimed to assess the impact of Lactobacillaceae (L or H represents a low or high dose), inulin (I), and polydextrose (P) combined with aerobic exercise (A) on the composition of the gut microbiota and metabolic profiles in db/db mice. After a 12-week intervention, LIP, LIPA, and HIPA groups exhibited significant improvements in hyperglycemia, glucose tolerance, insulin resistance, inflammatory response, and short-chain fatty acid (SCFA) and blood lipid levels compared to type 2 diabetes mice (MC). After treatment, the gut microbiota composition shifted favorably in the treatment groups which significantly increased the abundance of beneficial bacteria, such as Bacteroides, Blautia, Akkermansia, and Faecalibaculum, and significantly decreased the abundance of Proteus. Metabolomics analysis showed that compared to the MC group, the contents of 5-hydroxyindoleacetic acid, 3-hydroxysebacic acid, adenosine monophosphate (AMP), xanthine and hypoxanthine were significantly decreased, while 3-ketosphinganine, sphinganine, and sphingosine were significantly increased in the LIP and LIPA groups, respectively. Additionally, LIP and LIPA not only improved sphingolipid metabolism and purine metabolism pathways but also activated AMP-activated protein kinase to promote β-oxidation by increasing the levels of SCFAs. Faecalibaculum, Blautia, Bacteroides, and Akkermansia exhibited positive correlations with sphingosine, 3-ketosphinganine, and sphinganine, and exhibited negative correlations with hypoxanthine, xanthine and AMP. Faecalibaculum, Blautia, Bacteroides, and Akkermansia may have the potential to improve sphingolipid metabolism and purine metabolism pathways. These findings suggest that the synergism of Lactobacillaceae, inulin, polydextrose, and aerobic exercise provides a promising strategy for the prevention and management of type 2 diabetes.

The Significance of Bile in the Biliopancreatic Limb on Metabolic Improvement After Duodenal-Jejunal Bypass

INTRODUCTION

Duodenal-jejunal bypass (DJB) is an experimental procedure in metabolic surgery that does not have a restrictive component. Changes in bile acid (BA) dynamics and intestinal microbiota are possibly related to metabolic improvement after DJB. Our previous studies involving obese diabetic rats showed the crucial role of the biliopancreatic limb (BPL) in metabolic improvement after DJB caused by BA reabsorption. We established a new DJB procedure to prevent bile from flowing into the BPL and aimed to elucidate the importance of bile in the BPL after DJB.

METHODS

Otsuka Long-Evans Tokushima Fatty rats with diabetes were divided into three groups: two DJB groups and a sham group (n = 11). Duodenal-jejunal anastomosis was performed proximal to the papilla of Vater in the DJB group (n = 11). However, the DJB-D group (n = 11) underwent a new procedure with duodenal-jejunal anastomosis distal to the papilla of Vater for preventing bile flow into the BPL.

RESULTS

Glucose metabolism improved and weight gain was suppressed in the DJB group, but not in the DJB-D and sham groups. Serum BA level and conjugated BA concentration were elevated in the DJB group. The gut microbiota was altered only in the DJB group; the abundance of Firmicutes and Bacteroidetes decreased and that of Actinobacteria increased. However, the DJB-D group exhibited no apparent change in the gut microbiota, similar to the sham group.

CONCLUSION

BAs are essential in the BPL for metabolic improvement after DJB; they can improve the gut microbiota in these processes.

Influence of Bariatric Surgery on Gut Microbiota Composition and Its Implication on Brain and Peripheral Targets

Obesity remains a significant global health challenge, with bariatric surgery remaining as one of the most effective treatments for severe obesity and its related comorbidities. This review highlights the multifaceted impact of bariatric surgery beyond mere physical restriction or nutrient malabsorption, underscoring the importance of the gut microbiome and neurohormonal signals in mediating the profound effects on weight loss and behavior modification. The various bariatric surgery procedures, such as Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG), act through distinct mechanisms to alter the gut microbiome, subsequently impacting metabolic health, energy balance, and food reward behaviors. Emerging evidence has shown that bariatric surgery induces profound changes in the composition of the gut microbiome, notably altering the Firmicutes/Bacteroidetes ratio and enhancing populations of beneficial bacteria such as Akkermansia. These microbiota shifts have far-reaching effects beyond gut health, influencing dopamine-mediated reward pathways in the brain and modulating the secretion and action of key gut hormones including ghrelin, leptin, GLP-1, PYY, and CCK. The resultant changes in dopamine signaling and hormone levels contribute to reduced hedonic eating, enhanced satiety, and improved metabolic outcomes. Further, post-bariatric surgical effects on satiation targets are in part mediated by metabolic byproducts of gut microbiota like short-chain fatty acids (SCFAs) and bile acids, which play a pivotal role in modulating metabolism and energy expenditure and reducing obesity-associated inflammation, as well as influencing food reward pathways, potentially contributing to the regulation of body weight and reduction in hedonic eating behaviors. Overall, a better understanding of these mechanisms opens the door to developing non-surgical interventions that replicate the beneficial effects of bariatric surgery on the gut microbiome, dopamine signaling, and gut hormone regulation, offering new avenues for obesity treatment.

Preparation and characterisation of baicalin magnesium and its protective effect in ulcerative colitis via gut microbiota-bile acid axis modulation

BACKGROUND

Scutellaria baicalensis Georgi is a well-known herb in traditional Chinese medicine that is frequently prescribed for various gastrointestinal conditions, including ulcerative colitis (UC). Its primary active constituent, baicalin, has poorly water solubility that reduces its efficacy.

PURPOSE

To enhance the aqueous solubility of baicalin by optimising its extraction process. We compared the modulatory effects of isolated water-soluble baicalin and water-insoluble baicalin on UC, and delved deeper into the potential mechanisms of water-soluble baicalin.

METHODS

We successfully extracted a more hydrophilic baicalin directly from an aqueous S. baicalensis Georgi extract through the process of recrystallisation following alcoholic precipitation of the aqueous extract obtained from S. baicalensis Georgi, eliminating the need for acid additives. This specific form of baicalin was conclusively identified by UV, IR, atomic absorption spectroscopy, elemental analysis, 1H NMR, 13C NMR, and ESI-HRMS. We subsequently compared the regulatory effects of baicalin on UC before and after optimisation, employing 16S rDNA sequencing, bile acid-targeted metabolomics, and transcriptome analysis to elucidate the potential mechanism of water-soluble baicalin; and the key genes and proteins implicated in this mechanism were verified through RT-PCR and western blotting.

RESULTS

A new form of baicalin present in the aqueous solution of S. baicalensis Georgi was isolated, and its structural characterisation showed that it was bound to magnesium ions (baicalin magnesium) and exhibited favorable water solubility. Baicalin magnesium offers enhanced therapeutic benefits over baicalin for UC treatment, which alleviated the inflammatory response and oxidative stress levels while improving intestinal mucosal damage. Further investigation of the mechanism revealed that baicalin magnesium could effectively regulate bile acid metabolism and maintain intestinal microecological balance in UC mice, and suppress the activation of the nuclear factor-kappa B and peroxisome proliferator-activated receptor α signalling pathways, thereby playing a therapeutic role.

CONCLUSIONS

Baicalin magnesium has good water solubility, which solves the bottleneck problem of water insolubility in the practical applications of baicalin. Moreover, baicalin magnesium exhibits therapeutic potential for UC significantly better than baicalin.

Postbariatric surgery hypoglycemia: Nutritional, pharmacological and surgical perspectives

Post-bariatric hypoglycaemia (PBH) is a metabolic complication of bariatric surgery (BS), consisting of low post-prandial glucose levels in patients having undergone bariatric procedures. While BS is currently the most effective and relatively safe treatment for obesity and its complications, the development of PBH can significantly impact patients' quality of life and mental health. The diagnosis of PBH is still challenging, considering the lack of definitive and reliable diagnostic tools, and the fact that this condition is frequently asymptomatic. However, PBH's prevalence is alarming, involving up to 88% of the post-bariatric population, depending on the diagnostic tool, and this may be underestimated. Given the prevalence of obesity soaring, and an increasing number of bariatric procedures being performed, it is crucial that physicians are skilled to diagnose PBH and promptly treat patients suffering from it. While the milestone of managing this condition is nutritional therapy, growing evidence suggests that old and new pharmacological approaches may be adopted as adjunct therapies for managing this complex condition.

Evaluating Gut Microbiota Modification as a Next-Generation Therapy for Obesity and Diabetes

The human body is a complex ecosystem that thrives on symbiosis. It is estimated that around 10^14 commensal microorganisms inhabit the human body, with the gut microbiota being one of the most diverse and complex populations of bacteria. This community is thought to comprise over a thousand different species that play a crucial role in the development of critical human diseases such as cancer, obesity, diabetes, mental depression, hypertension, and others. The gut microbiota has been identified as one of the most recent contributors to these metabolic disorders. With the emergence of inexpensive and high-performance sequence technology, our understanding of the function of the intestinal microbiome in host metabolism regulation and the development of (cardio) metabolic diseases has increased significantly. The symbiotic relationship between the gut microbiota and the host is essential for properly developing the human metabolic system. However, if this balance is disrupted by various factors such as infection, diet, exercise, sleep patterns, or exposure to antibiotics, it can lead to the development of various diseases in the body, including obesity and diabetes type 1 and 2. While many approaches and medications have been developed globally to treat these diseases, none have proven to be entirely effective, and many show side effects. Therefore, scientists believe that treating the gut microbiota using tried-and-true methods is the best option for combating obesity and diabetes. In this study, we aim to identify several feasible ways and prospects for gut microbiota therapy that can shape a new format for the treatment of obesity and diabetes.

Transfer of microbiota from lean donors in combination with prebiotics prevents excessive weight gain and improves gut-brain vagal signaling in obese rats

Gastrointestinal (GI) microbiota plays an active role in regulating the host's immune system and metabolism, as well as certain pathophysiological processes. Diet is the main factor modulating GI microbiota composition and studies have shown that high fat (HF) diets induce detrimental changes (dysbiosis) in the GI bacterial makeup. HF diet induced dysbiosis has been associated with structural and functional changes in gut-brain vagally mediated signaling system, associated with overeating and obesity. Although HF-driven changes in microbiota composition are sufficient to alter vagal signaling, it is unknown if improving microbiota composition after diet-induced obesity has been established can ameliorate gut-brain signaling and metabolic outcomes. In this study, we evaluated the effect of lean gut microbiota transfer in obese, vagally compromised, rats on gut-brain communication, food intake, and body weight. Male rats were maintained on regular chow or 45% HF diet for nine weeks followed by three weeks of microbiota depletion using antibiotics. The animals were then divided into four groups (n = 10 each): LF - control fed regular chow, LF-LF - chow fed animals that received microbiota from chow fed donors, HF-LF - HF fed animals that received microbiota from chow fed donors, and HF-HF - HF fed animals that received microbiota from HF fed donors. HF-LF animals received inulin as a prebiotic to aid the establishment of the lean microbiome. We found that transferring a LF microbiota to HF fed animals (HF-LF) reduced caloric intake during the light phase when compared with HF-HF rats and prevented additional excessive weight gain. HF-LF animals displayed an increase in postprandial activation of both primary sensory neurons innervating the GI tract and brainstem secondary neurons. We concluded from these data that improving microbiota composition in obese rats is sufficient to ameliorate gut-brain communication and restore normal feeding patterns which was associated with a reduction in weight gain.

Comparative analysis of functional diversity of rumen microbiome in bison and beef heifers

IMPORTANCE

Ruminants play a key role in the conversion of cellulolytic plant material into high-quality meat and milk protein for humans. The rumen microbiome is the driver of this conversion, yet there is little information on how gene expression within the microbiome impacts the efficiency of this conversion process. The current study investigates gene expression in the rumen microbiome of beef heifers and bison and how transplantation of ruminal contents from bison to heifers alters gene expression. Understanding interactions between the host and the rumen microbiome is the key to developing informed approaches to rumen programming that will enhance production efficiency in ruminants.

Evidence for the contribution of the gut microbiome to obesity and its reversal

Obesity has become a worldwide pandemic affecting more than 650 million people and is associated with a high burden of morbidity. Alongside traditional risk factors for obesity, the gut microbiome has been identified as a potential factor in weight regulation. Although rodent studies suggest a link between the gut microbiome and body weight, human evidence for causality remains scarce. In this Review, we postulate that existing evidence remains to establish a contribution of the gut microbiome to the development of obesity in humans but that modified probiotic strains and supraphysiological dosages of microbial metabolites may be beneficial in combatting obesity.

Bariatric Surgery and Gut-Brain-Axis Driven Alterations in Cognition and Inflammation

Obesity is associated with systemic inflammation, comorbidities like diabetes, cardiovascular disease and several cancers, cognitive decline and structural and functional brain changes. To treat, or potentially prevent these related comorbidities, individuals with obesity must achieve long-term sustainable weight loss. Often life style interventions, such as dieting and increased physical activity are not successful in achieving long-term weight loss. Meanwhile bariatric surgery has emerged as a safe and effective procedure to treat obesity. Bariatric surgery causes changes in physiological processes, but it is still not fully understood which exact mechanisms are involved. The successful weight loss after bariatric surgery might depend on changes in various energy regulating hormones, such as ghrelin, glucagon-like peptide-1 and peptide YY. Moreover, changes in microbiota composition and white adipose tissue functionality might play a role. Here, we review the effect of obesity on neuroendocrine effects, microbiota composition and adipose tissue and how these may affect inflammation, brain structure and cognition. Finally, we will discuss how these obesity-related changes may improve after bariatric surgery.

The Characteristics, Mechanisms and Therapeutics: Exploring the Role of Gut Microbiota in Obesity

Presently, obesity has emerged as a significant global public health concern due to its escalating prevalence and incidence rates. The gut microbiota, being a crucial environmental factor, has emerged as a key player in the etiology of obesity. Nevertheless, the intricate and specific interactions between obesity and gut microbiota, along with the underlying mechanisms, remain incompletely understood. This review comprehensively summarizes the gut microbiota characteristics in obesity, the mechanisms by which it induces obesity, and explores targeted therapies centered on gut microbiota restoration.

Sleeve Gastrectomy Provides Cardioprotection from Oxidative Stress In Vitro Due to Reduction of Circulating Myeloperoxidase

Bariatric surgery, including sleeve gastrectomy (SG), improves systolic and diastolic function, which is independent of weight loss in rodent models. The cause of weight loss-independent improvements in cardiac function are unknown but may originate from the gastrointestinal tract. In this study, we investigated whether a circulating blood factor is a mechanism for acute cardioprotection after SG by testing the utility of rodent SG plasma to reduce metabolic stress in vitro. For the initial experiment, obese male Zucker rats underwent SG, ad lib sham, or pair-fed sham surgeries (n = six SG, n = eight SH, n = eight PF). For all other studies, a second group of Zucker rats underwent SG or ad lib sham surgeries (n = eight SH, n = six SG). Six weeks following surgery, plasma was collected from each group, both in the fasting and post-prandial (pp) state. This plasma was then pooled per surgical group and nutrient state and tested in multiple in vitro cell culture and extra-cellular assays to determine the effect of SG on myotubular metabolic stress compared to the sham surgeries. Post-prandial SG plasma (ppSG), but not fasting SG, pp, or fasting sham plasma, reduced the metabolic stress of the H9c2 cells as measured by lactate dehydrogenase (LDH) release (p < 0.01). Unlike SG, weight reduction through pair-feeding did not prevent H9c2 metabolic stress. The PpSG plasma had the slowest rate of extracellular hydrogen peroxide consumption and peroxidatic activity compared to the pp sham, fasting SG, and fasting sham groups. Redox testing of plasma with aminiobenzoic acid hydrazide and edaravone suggested a pattern supporting myeloperoxidase (MPO), or other peroxidases, as the primary component responsible for reduced metabolic stress with ppSG plasma. The PpSG plasma contained 35% less circulating MPO protein as compared to the pp sham and fasting SG plasma. The plasma from an MPO global knockout rat also prevented metabolic stress of the H9c2 cells, compared to the significant increase in LDH release from the plasma of the WT controls (p < 0.01). The MPO global knockout plasma also had a rate of extracellular hydrogen peroxide consumption and peroxidatic activity comparable to the ppSG plasma. These studies suggest that one of the weight loss-independent mechanisms by which SG improves myocellular function could be a reduced pro-oxidative environment due to lower circulating levels of MPO. It appears that the gastrointestinal tract is of critical importance to these findings, as the MPO levels were only lowered after enteral, nutrient stimulation in the SG rats. If this surgical effect is confirmed in humans, SG may be a unique surgical treatment for multiple diseases with a pathogenesis of inflammation and oxidative damage, including obesity-associated heart failure with preserved ejection fraction.

Hepatic lipid-associated macrophages mediate the beneficial effects of bariatric surgery against MASH

For patients with obesity and metabolic syndrome, bariatric procedures such as vertical sleeve gastrectomy (VSG) have a clear benefit in ameliorating metabolic dysfunction-associated steatohepatitis (MASH). While the effects of bariatric surgeries have been mainly attributed to nutrient restriction and malabsorption, whether immuno-modulatory mechanisms are involved remains unclear. Here we report that VSG ameliorates MASH progression in a weight loss-independent manner. Single-cell RNA sequencing revealed that hepatic lipid-associated macrophages (LAMs) expressing the triggering receptor expressed on myeloid cells 2 (TREM2) increase their lysosomal activity and repress inflammation in response to VSG. Remarkably, TREM2 deficiency in mice ablates the reparative effects of VSG, suggesting that TREM2 is required for MASH resolution. Mechanistically, TREM2 prevents the inflammatory activation of macrophages and is required for their efferocytotic function. Overall, our findings indicate that bariatric surgery improves MASH through a reparative process driven by hepatic LAMs, providing insights into the mechanisms of disease reversal that may result in new therapies and improved surgical interventions.

Questioning the foundations of the gut microbiota and obesity

The role of the gut microbiota in determining body fatness has been a prominent area of research and has received significant public attention. Based largely on animal studies, recent attempts to translate these findings into interventions in humans have not been successful. This review will outline the key mouse research that initiated this area of study, examine whether those results warranted the initial enthusiasm and progress into human studies, and examine whether later follow-up research supported earlier conclusions. It will look at whether the absence of a gut microbiota protects germ-free mice from obesity, whether microbiota can transfer obesity into germ-free mice, the evidence for the role of immune system activation as a causal mechanism linking the gut microbiota to body weight, and consider the evidence for effects of individual bacterial species. Finally, it will examine the outcomes of randomized controlled trials of microbiota transfer in human participants that have not shown effects on body weight. With a more critical reading, early studies did not show as large an effect as first appeared and later research, including human trials, has failed to support a role of the gut microbiota in shaping body weight. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part II)'.

Differential effects of plant-based flours on metabolic homeostasis and the gut microbiota in high-fat fed rats

BACKGROUND

The gut microbiome is a salient contributor to the development of obesity, and diet is the greatest modifier of the gut microbiome, which highlights the need to better understand how specific diets alter the gut microbiota to impact metabolic disease. Increased dietary fiber intake shifts the gut microbiome and improves energy and glucose homeostasis. Dietary fibers are found in various plant-based flours which vary in fiber composition. However, the comparative efficacy of specific plant-based flours to improve energy homeostasis and the mechanism by which this occurs is not well characterized.

METHODS

In experiment 1, obese rats were fed a high fat diet (HFD) supplemented with four different plant-based flours for 12 weeks. Barley flour (BF), oat bran (OB), wheat bran (WB), and Hi-maize amylose (HMA) were incorporated into the HFD at 5% or 10% total fiber content and were compared to a HFD control. For experiment 2, lean, chow-fed rats were switched to HFD supplemented with 10% WB or BF to determine the preventative efficacy of flour supplementation.

RESULTS

In experiment 1, 10% BF and 10% WB reduced body weight and adiposity gain and increased cecal butyrate. Gut microbiota analysis of WB and BF treated rats revealed increases in relative abundance of SCFA-producing bacteria. 10% WB and BF were also efficacious in preventing HFD-induced obesity; 10% WB and BF decreased body weight and adiposity, improved glucose tolerance, and reduced inflammatory markers and lipogenic enzyme expression in liver and adipose tissue. These effects were accompanied by alterations in the gut microbiota including increased relative abundance of Lactobacillus and LachnospiraceaeUCG001, along with increased portal taurodeoxycholic acid (TDCA) in 10% WB and BF rats compared to HFD rats.

CONCLUSIONS

Therapeutic and preventative supplementation with 10%, but not 5%, WB or BF improves metabolic homeostasis, which is possibly due to gut microbiome-induced alterations. Specifically, these effects are proposed to be due to increased concentrations of intestinal butyrate and circulating TDCA.

A specific gut microbiota signature is associated with an enhanced GLP-1 and GLP-2 secretion and improved metabolic control in patients with type 2 diabetes after metabolic Roux-en-Y gastric bypass

Objective

To determine changes in incretins, systemic inflammation, intestinal permeability and microbiome modifications 12 months after metabolic RYGB (mRYGB) in patients with type 2 diabetes (T2D) and their relationship with metabolic improvement.

Materials and methods

Prospective single-center non-randomized controlled study, including patients with class II-III obesity and T2D undergoing mRYGB. At baseline and one year after surgery we performed body composition measurements, biochemical analysis, a meal tolerance test (MTT) and lipid test (LT) with determination of the area under the curve (AUC) for insulin, C-peptide, GLP-1, GLP-2, and fasting determinations of succinate, zonulin, IL-6 and study of gut microbiota.

Results

Thirteen patients aged 52.6 ± 6.5 years, BMI 39.3 ± 1.4 kg/m2, HbA1c 7.62 ± 1.5% were evaluated. After mRYGB, zonulin decreased and an increase in AUC after MTT was observed for GLP-1 (pre 9371 ± 5973 vs post 15788 ± 8021 pM, P<0.05), GLP-2 (pre 732 ± 182 vs post 1190 ± 447 ng/ml, P<0.001) and C- peptide, as well as after LT. Species belonging to Streptococaceae, Akkermansiacea, Rickenellaceae, Sutterellaceae, Enterobacteriaceae, Oscillospiraceae, Veillonellaceae, Enterobacterales_uc, and Fusobacteriaceae families increased after intervention and correlated positively with AUC of GLP-1 and GLP-2, and negatively with glucose, HbA1c, triglycerides and adiposity markers. Clostridium perfringens and Roseburia sp. 40_7 behaved similarly. In contrast, some species belonging to Lachnospiraceae, Erysipelotricaceae, and Rumnicocaceae families decreased and showed opposite correlations. Higher initial C-peptide was the only predictor for T2D remission, which was achieved in 69% of patients.

Conclusions

Patients with obesity and T2D submitted to mRYGB show an enhanced incretin response, a reduced gut permeability and a metabolic improvement, associated with a specific microbiota signature.

Contribution of the microbiome for better phenotyping of people living with obesity

Obesity has reached epidemic proportion worldwide and in all ages. Available evidence points to a multifactorial pathogenesis involving gene predisposition and environmental factors. Gut microbiota plays a critical role as a major interface between external factors, i.e., diet, lifestyle, toxic chemicals, and internal mechanisms regulating energy and metabolic homeostasis, fat production and storage. A shift in microbiota composition is linked with overweight and obesity, with pathogenic mechanisms involving bacterial products and metabolites (mainly endocannabinoid-related mediators, short-chain fatty acids, bile acids, catabolites of tryptophan, lipopolysaccharides) and subsequent alterations in gut barrier, altered metabolic homeostasis, insulin resistance and chronic, low-grade inflammation. Although animal studies point to the links between an "obesogenic" microbiota and the development of different obesity phenotypes, the translational value of these results in humans is still limited by the heterogeneity among studies, the high variation of gut microbiota over time and the lack of robust longitudinal studies adequately considering inter-individual confounders. Nevertheless, available evidence underscores the existence of several genera predisposing to obesity or, conversely, to lean and metabolically health phenotype (e.g., Akkermansia muciniphila, species from genera Faecalibacterium, Alistipes, Roseburia). Further longitudinal studies using metagenomics, transcriptomics, proteomics, and metabolomics with exact characterization of confounders are needed in this field. Results must confirm that distinct genera and specific microbial-derived metabolites represent effective and precision interventions against overweight and obesity in the long-term.

The gut-brain axis mediates bacterial driven modulation of reward signaling

OBJECTIVE

Our goal is to investigate if microbiota composition modulates reward signaling and assess the role of the vagus in mediating microbiota to brain communication.

METHODS

Male germ-free Fisher rats were colonized with gastrointestinal contents from chow (low fat (LF) ConvLF) or HF (ConvHF) fed rats.

RESULTS

Following colonization, ConvHF rats consumed significantly more food than ConvLF animals. ConvHF rats displayed lower feeding-induced extracellular DOPAC levels (a metabolite of dopamine) in the Nucleus Accumbens (NAc) as well as reduced motivation for HF foods compared to ConvLF rats. Dopamine receptor 2 (DDR2) expression levels in the NAc were also significantly lower in ConvHF animals. Similar deficits were observed in conventionally raised HF fed rats, showing that diet-driven alteration in reward can be initiated via microbiota. Selective gut to brain deafferentation restored DOPAC levels, DRD2 expression, and motivational drive in ConvHF rats.

CONCLUSIONS

We concluded from these data that a HF-type microbiota is sufficient to alter appetitive feeding behavior and that bacteria to reward communication is mediated by the vagus nerve.

Roles of the gut microbiome in weight management

Overweight, obesity, undernutrition and their respective sequelae have devastating tolls on personal and public health worldwide. Traditional approaches for treating these conditions with diet, exercise, drugs and/or surgery have shown varying degrees of success, creating an urgent need for new solutions with long-term efficacy. Owing to transformative advances in sequencing, bioinformatics and gnotobiotic experimentation, we now understand that the gut microbiome profoundly impacts energy balance through diverse mechanisms affecting both sides of the energy balance equation. Our growing knowledge of microbial contributions to energy metabolism highlights new opportunities for weight management, including the microbiome-aware improvement of existing tools and novel microbiome-targeted therapies. In this Review, we synthesize current knowledge concerning the bidirectional influences between the gut microbiome and existing weight management strategies, including behaviour-based and clinical approaches, and incorporate a subject-level meta-analysis contrasting the effects of weight management strategies on microbiota composition. We consider how emerging understanding of the gut microbiome alters our prospects for weight management and the challenges that must be overcome for microbiome-focused solutions to achieve success.

Differences in metabolic improvement after metabolic surgery are linked to the gut microbiota in non-obese diabetic rats

BACKGROUND

Different metabolic/bariatric surgery approaches vary in their effect on weight loss and glucose levels, although the underlying mechanism is unclear. Studies have demonstrated that the gut microbiota might be an important mechanism of improved metabolism after metabolic/bariatric surgery.

AIM

To investigate the relationship between the improvement in metabolic disturbances and the changes in gut microbiota after gastric or intestinal bypass.

METHODS

We performed sleeve gastrectomy (SG), distal small intestine bypass (DSIB) or sham surgery in nonobese rats with diabetes induced by 60 mg/kg streptozotocin (STZ-DM).

RESULTS

The group comparisons revealed that both SG and DSIB induced a reduction in body weight and significant improvements in glucose and lipid metabolism in the STZ-DM rats. Furthermore, DSIB exhibited a stronger glucose-lowering and lipid-reducing effect on STZ-DM rats than SG. 16S ribosomal RNA gene sequencing revealed the gut abundance of some Lactobacillus spp. increased in both the SG and DSIB groups after surgery. However, the DSIB group exhibited a more pronounced increase in the gut abundance of Lactobacillus spp. compared to the SG group, with more Lactobacillus spp. types increased in the gut.

CONCLUSION

The gut abundance of Lactobacillus was significantly correlated with the improvement in glycolipid metabolism and the change in serum fibroblast growth factor 21 levels.

Cardiovascular Effects of Weight Loss in Obese Patients with Diabetes: Is Bariatric Surgery the Additional Arrow in the Quiver?

Obesity is an increasingly widespread disease worldwide because of lifestyle changes. It is associated with an increased risk of cardiovascular disease, primarily type 2 diabetes mellitus, with an increase in major cardiovascular adverse events. Bariatric surgery has been shown to be able to reduce the incidence of obesity-related cardiovascular disease and thus overall mortality. This result has been shown to be the result of hormonal and metabolic effects induced by post-surgical anatomical changes, with important effects on multiple hormonal and molecular axes that make this treatment more effective than conservative therapy in determining a marked improvement in the patient's cardiovascular risk profile. This review, therefore, aimed to examine the surgical techniques currently available and how these might be responsible not only for weight loss but also for metabolic improvement and cardiovascular benefits in patients undergoing such procedures.

Plasma short-chain fatty acid changes after bariatric surgery in patients with severe obesity

BACKGROUND

Obesity has reached epidemic dimensions in recent decades. Bariatric surgery (BS) is one of the most effective interventions for weight loss and metabolic improvement in patients with obesity. Short-chain fatty acids (SCFA) are gut microbiota-derived metabolites with a key role in body weight control and insulin sensitivity. Although BS is known to induce significant changes in the gut microbiota composition, its impact on the circulating levels of certain metabolites produced by the gut microbiota such as SCFA remains poorly understood.

OBJECTIVE

To determine the impact of BS on the circulating SCFA levels in patients with severe obesity.

SETTING

University hospital.

METHODS

An observational, prospective study was performed on 51 patients undergoing Roux-en-Y gastric bypass. Plasma samples were collected at baseline (1 day before surgery) and at 6 and 12 months after BS. Plasma SCFA levels were determined by liquid chromatography-mass spectrometry.

RESULTS

The results revealed significant changes in the circulating levels of SCFA after BS. A marked increase in propionate, butyrate, isobutyrate, and isovalerate levels and a decrease in acetate, valerate, hexanoate, and heptanoate levels were observed 12 months after BS. Furthermore, the changes in the levels of propionate, butyrate, and isobutyrate negatively correlated with changes in body mass index, while those of isobutyrate correlated negatively with changes in the homeostatic model assessment for insulin resistance index.

CONCLUSION

These results suggest that propionate, butyrate, and isobutyrate levels could be related to weight loss and improved insulin sensitivity in patients with severe obesity after BS.

Gut Microbiota Contribution to Weight-Independent Glycemic Improvements after Gastric Bypass Surgery

Roux-en-Y gastric bypass surgery (RYGB) leads to improved glycemic control in individuals with severe obesity beyond the effects of weight loss alone. Here, We addressed the potential contribution of gut microbiota in mediating this favourable surgical outcome by using an established preclinical model of RYGB. 16S rRNA sequencing revealed that RYGB-treated Zucker fatty rats had altered fecal composition of various bacteria at the phylum and species levels, including lower fecal abundance of an unidentified Erysipelotrichaceae species, compared with both sham-operated (Sham) and body weight-matched to RYGB-treated (BWM) rats. Correlation analysis further revealed that fecal abundance of this unidentified Erysipelotrichaceae species linked with multiple indices of glycemic control uniquely in RYGB-treated rats. Sequence alignment of this Erysipelotrichaceae species identified Longibaculum muris to be the most closely related species, and its fecal abundance positively correlated with oral glucose intolerance in RYGB-treated rats. In fecal microbiota transplant experiments, the improved oral glucose tolerance of RYGB-treated compared with BWM rats could partially be transferred to recipient germfree mice, independently of body weight. Unexpectedly, providing L. muris as a supplement to RYGB recipient mice further improved oral glucose tolerance, while administering L. muris alone to chow-fed or Western style diet-challenged conventionally raised mice had minimal metabolic impact. Taken together, our findings provide evidence that the gut microbiota contributes to weight loss-independent improvements in glycemic control after RYGB and demonstrate how correlation of a specific gut microbiota species with a host metabolic trait does not imply causation. IMPORTANCE Metabolic surgery remains the most effective treatment modality for severe obesity and its comorbidities, including type 2 diabetes. Roux-en-Y gastric bypass (RYGB) is a commonly performed type of metabolic surgery that reconfigures gastrointestinal anatomy and profoundly remodels the gut microbiota. While it is clear that RYGB is superior to dieting when it comes to improving glycemic control, the extent to which the gut microbiota contributes to this effect remains untested. In the present study, we uniquely linked fecal Erysipelotrichaceae species, including Longibaculum muris, with indices of glycemic control after RYGB in genetically obese and glucose-intolerant rats. We further show that the weight loss-independent improvements in glycemic control in RYGB-treated rats can be transmitted via their gut microbiota to germfree mice. Our findings provide rare causal evidence that the gut microbiota contributes to the health benefits of metabolic surgery and have implications for the development of gut microbiota-based treatments for type 2 diabetes.

Alterations of gut microbiome following gastrointestinal surgical procedures and their potential complications

Intestinal microorganisms play a crucial role in shaping the host immunity and maintaining homeostasis. Nevertheless, alterations in gut bacterial composition may occur and these alterations have been linked with the pathogenesis of several diseases. In surgical practice, studies revealed that the microbiome of patients undergoing surgery changes and several post-operative complications seem to be associated with the gut microbiota composition. In this review, we aim to provide an overview of gut microbiota (GM) in surgical disease. We refer to several studies which describe alterations of GM in patients undergoing different types of surgery, we focus on the impacts of peri-operative interventions on GM and the role of GM in development of post-operative complications, such as anastomotic leak. The review aims to enhance comprehension regarding the correlation between GM and surgical procedures based in the current knowledge. However, preoperative and postoperative synthesis of GM needs to be further examined in future studies, so that GM-targeted measures could be assessed and the different surgery complications could be reduced.

Physical properties of food or bile redirection do not contribute to the intestinal adaptations after Roux-en-Y Gastric Bypass in rats

Objective

Metabolic and morphological adaptations of the intestine have been suggested to play a role in the various therapeutic benefits of Roux-en-Y Gastric Bypass (RYGB) surgery. However, the precise underlying mechanisms remain unclear. In this study, the effects of physical properties of ingested food and redirection of biliopancreatic secretions on intestinal remodeling were investigated in RYGB operated rats.

Methods

RYGB employing two different Roux Limb (RL) lengths was performed on high fat diet induced obese rats. Post-operatively, rats were fed either Solid or isocaloric Liquid diets. Metabolic and morphological remodeling of intestine was compared across both diet forms (Solid and Liquid diets) and surgical models (Short RL and Long RL).

Results

RYGB surgery in rats induced weight loss and improved glucose tolerance which was independent of physical properties of ingested food and biliopancreatic secretions. Intestinal glucose utilization after RYGB was not determined by either food form or biliopancreatic secretions. The GLUT-1 expression in RL was not influenced by physical properties of food. Furthermore, both physical properties of food and biliopancreatic secretions showed no effects on intestinal morphological adaptations after RYGB.

Conclusion

Results of this study demonstrate that physical properties of food and bile redirection are not major determinants of intestinal remodeling after RYGB in rats.