Metabolic improvement in obese patients after duodenal-jejunal exclusion is associated with intestinal microbiota composition changes

The role of the gut microbiome in weight-gain in schizophrenia patients treated with atypical antipsychotics: Evidence based on altered composition and function in a cross-sectional study

OBJECTIVES

We aimed to explore the interconnection between the weight-gain in schizophrenia patients with atypical antipsychotic treatment and gut microbiome.

METHODS

This study employed a cross-sectional design, encompassing a total of 88 schizophrenia patients with long-term atypical antipsychotic treatment. The 16S rRNA gene sequencing was used to identify gut microbiome contents.

RESULTS

No significant differences in alpha diversity between normal-weight and overweight schizophrenia treated with atypical antipsychotics. The beta diversity analysis showed that overweight patients clustered tightly while normal-weight patients clustered widely. For taxonomic composition, overweight patients had a lower relative abundance in Porphyromonadaceae at family level and Butyrivibrio at genus level, but higher relative abundance in Ruminococcus2 and Clostridium_XIVa at genus level than normal-weight patients. Function prediction revelated that four pathways (including Cell cycle, Non-homologous end-joining, Vibrio cholerae infection and Meiosis-yeast) were significantly different between groups. Correlation analysis indicated that Klebsiella, Butyrivibrio, Unassigned, Methanosphaera, Holdemania, Anaerotruncus were negatively, while Veillonella was positively correlated with BMI in patients.

CONCLUSION

Our findings offer evidence that perturbations in the gut microbiome composition, encompassing taxa such as Porphyromonadaceae, Butyrivibrio, Ruminococcus2, and Clostridium_XIVa, in conjunction with distinct functional pathways including Cell cycle, Non-homologous end-joining, Vibrio cholerae infection, and Meiosis-yeast, might contribute to the weight-gain in schizophrenia treated with atypical antipsychotics.

Small intestine-targeted endoscopic bariatrics: Current status and future perspectives

The global obesity epidemic shows no signs of slowing down. Endoscopic bariatric and metabolic therapies (EBMTs) are being increasingly adopted as treatment options for obesity and obesity-related comorbidities, due to their minimally invasive nature and ease of delivery. According to the site of action along the gastrointestinal tract, EBMTs can be divided into two categories: gastric EBMTs, and small intestine-targeted EBMTs. Unlike gastric EBMTs, which work through a volume-restricting mechanism leading to early satiety and reduced caloric intake, small intestine-targeted EBMTs can be metabolically beneficial through foregut and/or hindgut pathways independent of weight loss, and therefore have great potential for the treatment of obesity-related metabolic comorbidities such as type 2 diabetes. Although none of the small intestine-targeted EBMTs have been approved by the US Food and Drug Administration to date, their clinical efficacy and safety have been extensively explored in investigational trials. This review aims to summarize and provide a comprehensive understanding of small intestine-targeted EBMTs in clinical and preclinical settings, and to further discuss their potential mechanisms of action.

The Black Box Orchestra of Gut Bacteria and Bile Acids: Who Is the Conductor?

Over the past decades the potential role of the gut microbiome and bile acids in type 2 diabetes mellitus (T2DM) has been revealed, with a special reference to low bacterial alpha diversity. Certain bile acid effects on gut bacteria concern cytotoxicity, or in the case of the microbiome, bacteriotoxicity. Reciprocally, the gut microbiome plays a key role in regulating the bile acid pool by influencing the conversion and (de)conjugation of primary bile acids into secondary bile acids. Three main groups of bacterial enzymes responsible for the conversion of bile acids are bile salt hydrolases (BSHs), hydroxysteroid dehydrogenases (HSDHs) and enzymes encoded in the bile acid inducible (Bai) operon genes. Interventions such as probiotics, antibiotics and fecal microbiome transplantation can impact bile acids levels. Further evidence of the reciprocal interaction between gut microbiota and bile acids comes from a multitude of nutritional interventions including macronutrients, fibers, prebiotics, specific individual products or diets. Finally, anatomical changes after bariatric surgery are important because of their metabolic effects. The heterogeneity of studies, diseases, bacterial species and (epi)genetic influences such as nutrition may challenge establishing specific and detailed interventions that aim to tackle the gut microbiome and bile acids.

Endoscopic Bariatric and Metabolic Therapies for Liver Disease: Mechanisms, Benefits, and Associated Risks

Nonalcoholic fatty liver disease (NAFLD), including advanced-stage nonalcoholic steatohepatitis (NASH), is currently the most common chronic liver disease worldwide and is projected to become the leading indication for liver transplantation (LT). However, there are no effective pharmacological therapies for NAFLD. Endoscopic bariatric and metabolic therapies (EBMTs) are less invasive procedures for the treatment of obesity and its metabolic comorbidities. Several recent studies have demonstrated the beneficial effects of EBMTs on NAFLD/NASH. In this review, we summarize the major EBMTs and their mechanisms of action. We further discuss the current evidence on the efficacy and safety of EBMTs in people with NAFLD/NASH and obese cirrhotic LT candidates. The potential utility of EBMTs in reducing liver volume and perioperative complications in bariatric surgery candidates is also discussed. Moreover, we review the development of liver abscesses as a common serious adverse event in duodenal-jejunal bypass liner implantation.

Gut microbiome and microbial metabolites in NAFLD and after bariatric surgery: Correlation and causality

Non-alcoholic fatty liver disease (NAFLD) is currently related to a heavy socioeconomic burden and increased incidence. Since obesity is the most prevalent risk factor for NAFLD, weight loss is an effective therapeutic solution. Bariatric surgery (BS), which can achieve long-term weight loss, improves the overall health of patients with NAFLD. The two most common surgeries are the Roux-en-Y gastric bypass and sleeve gastrectomy. The gut-liver axis is the complex network of cross-talking between the gut, its microbiome, and the liver. The gut microbiome, involved in the homeostasis of the gut-liver axis, is believed to play a significant role in the pathogenesis of NAFLD and the metabolic improvement after BS. Alterations in the gut microbiome in NAFLD have been confirmed compared to that in healthy individuals. The mechanisms linking the gut microbiome to NAFLD have been proposed, including increased intestinal permeability, higher energy intake, and other pathophysiological alterations. Interestingly, several correlation studies suggested that the gut microbial signatures after BS become more similar to those of lean, healthy controls than that of patients with NAFLD. The resolution of NAFLD after BS is related to changes in the gut microbiome and its metabolites. However, confirming a causal link remains challenging. This review summarizes characteristics of the gut microbiome in patients with NAFLD before and after BS and accumulates existing evidence about the underlying mechanisms of the gut microbiome.

A Changed Gut Microbiota Diversity Is Associated With Metabolic Improvements After Duodenal Mucosal Resurfacing With Glucagon-Like-Peptide-1 Receptor Agonist in Type 2 Diabetes in a Pilot Study

Introduction

The gut microbiota influences and interacts with the host metabolism through effects on nutrient metabolism and digestion. Duodenal Mucosal Resurfacing (DMR) is a novel endoscopic procedure involving duodenal mucosal ablation by the use of hydrothermal energy. DMR, when combined with a glucagon-like peptide-1 receptor agonist (GLP-1RA), resulted in discontinuation of exogenous insulin treatment in 69% of patients with insulin dependent type 2 diabetes mellitus (T2DM) in the INSPIRE study. These patients also experienced improved glycaemic control and metabolic health. We thus investigated if these clinical effects were associated with a change in gut microbiota alpha and beta diversity.

Methods

Faecal samples from the 16 patients were obtained for Illumina shotgun sequencing at baseline and 3 months after DMR. We assessed alpha and beta diversity of the gut microbiota in these samples and analysed its correlations with changes in HbA1c, body weight, and liver MRI proton density fat fraction (PDFF).

Results

HbA1c correlated negatively with alpha diversity (p=0.011, rho: -0.62) whereas changes in PDFF correlated significantly with beta diversity (p=0.036, rho: 0.55) 3 months after initiation of the combined intervention. These correlations with metabolic parameters were observed despite finding no change in gut microbiota diversity at 3 months post DMR.

Discussion

The correlation between gut microbiota richness (alpha diversity) and HbA1c as well as the change in PDFF and changed microbiota composition (beta diversity) suggests that changed gut microbiota diversity is associated with metabolic improvements after DMR in combination with glucagon-like-peptide-1 receptor agonist in type 2 diabetes. Larger controlled studies are however needed to find causal links between DMR with GLP-1RA, the gut microbiota, and improvements in metabolic health.

The impact of dietary, surgical, and pharmacological interventions on gut microbiota in individuals with diabetes mellitus: A systematic review

AIMS

To conduct a systematic review assessing the association between dietary, surgical, and pharmacological interventions and changes in the gut microbiota of individuals with diabetes.

METHODS

The MEDLINE, EMBASE, and Cochrane Library databases were searched focusing on the effects of dietary, bariatric surgery, and pharmacological interventions on gut microbiota in adults with diabetes. Studies were classified based on qualitative changes using a simple vote-counting method, evaluating reduction, no effect, or an increase in the gut microbiota outcomes.

RESULTS

6,004 studies were retained to review their titles and abstracts. A total of 149 full-text articles were reassessed, of which 49 were included in the final analysis. This review indicates that dietary, surgical, and pharmacological interventions increase or decrease bacterial populations from more than 60 families, genera, or species. In general, the interventions led to an increase in the bacterial population from phylum Firmicutes, mainly Lactobacillus species, compared to the gram-negative bacterial population from phylum Bacteroidetes.

CONCLUSIONS

The results of the included studies suggest that interventions aimed at reducing species related to uncontrolled diabetes and increasing species related to the healthy gut are potential adjuvants in treating diabetes; however, well-conducted interventional studies targeting gut microbiota are necessary.

Gut microbiota and related metabolites in the pathogenesis of nonalcoholic steatohepatitis and its resolution after bariatric surgery

Nonalcoholic fatty liver disease (NAFLD) is increasing in parallel with the rising prevalence of obesity, leading to major health and socioeconomic consequences. To date, the most effective therapeutic approach for NAFLD is weight loss. Accordingly, bariatric surgery (BS), which produces marked reductions in body weight, is associated with significant histopathological improvements in advanced stages of NAFLD, such as nonalcoholic steatohepatitis (NASH) and liver fibrosis. BS is also associated with substantial taxonomical and functional alterations in gut microbiota, which are believed to play a significant role in metabolic improvement after BS. Interestingly, gut microbiota and related metabolites may be implicated in the pathogenesis of NAFLD through diverse mechanisms, including specific microbiome signatures, short chain fatty acid production or the modulation of one-carbon metabolism. Moreover, emerging evidence highlights the potential association between gut microbiota changes after BS and NASH resolution. In this review, we summarize the current knowledge on the relationship between NAFLD severity and gut microbiota, as well as the role of the gut microbiome and related metabolites in NAFLD improvement after BS.

Roux-en-Y gastric bypass surgery in Zucker rats induces bacterial and systemic metabolic changes independent of caloric restriction-induced weight loss

Mechanisms of Roux-en-Y gastric bypass (RYGB) surgery are not fully understood. This study aimed to investigate weight loss-independent bacterial and metabolic changes, as well as the absorption of bacterial metabolites and bile acids through the hepatic portal system following RYGB surgery. Three groups of obese Zucker (fa/fa) rats were included: RYGB (n = 11), sham surgery and body weight matched with RYGB (Sham-BWM, n = 5), and sham surgery fed ad libitum (Sham-obese, n = 5). Urine and feces were collected at multiple time points, with portal vein and peripheral blood obtained at the end of the study. Metabolic phenotyping approaches and 16S rRNA gene sequencing were used to determine the biochemical and bacterial composition of the samples, respectively. RYGB surgery-induced distinct metabolic and bacterial disturbances, which were independent of weight loss through caloric restriction. RYGB resulted in lower absorption of phenylalanine and choline, and higher urinary concentrations of host-bacterial co-metabolites (e.g., phenylacetylglycine, indoxyl sulfate), together with higher fecal trimethylamine, suggesting enhanced bacterial aromatic amino acid and choline metabolism. Short chain fatty acids (SCFAs) were lower in feces and portal vein blood from RYGB group compared to Sham-BWM, accompanied with lower abundances of Lactobacillaceae, and Ruminococcaceae known to contain SCFA producers, indicating reduced bacterial fiber fermentation. Fecal γ-amino butyric acid (GABA) was found in higher concentrations in RYGB than that in Sham groups and could play a role in the metabolic benefits associated with RYGB surgery. While no significant difference in urinary BA excretion, RYGB lowered both portal vein and circulating BA compared to Sham groups. These findings provide a valuable resource for how dynamic, multi-systems changes impact on overall metabolic health, and may provide potential therapeutic targets for developing downstream non-surgical treatment for metabolic disease.

Mechanisms of Weight Loss After Obesity Surgery

Obesity surgery remains the most effective treatment for obesity and its complications. Weight loss was initially attributed to decreased energy absorption from the gut but has since been linked to reduced appetitive behavior and potentially increased energy expenditure. Implicated mechanisms associating rearrangement of the gastrointestinal tract with these metabolic outcomes include central appetite control, release of gut peptides, change in microbiota, and bile acids. However, the exact combination and timing of signals remain largely unknown. In this review, we survey recent research investigating these mechanisms, and seek to provide insights on unanswered questions over how weight loss is achieved following bariatric surgery which may eventually lead to safer, nonsurgical weight-loss interventions or combinations of medications with surgery.

Effects of Bariatric Endoscopy on Non-Alcoholic Fatty Liver Disease: A Comprehensive Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVE

Endoscopic bariatric and metabolic therapies (EBMTs) are emerging minimally invasive therapeutic options for obesity and its related complications, including non-alcoholic fatty liver disease (NAFLD). This study aimed to evaluate the effects of EBMTs on NALFD in patients with obesity.

METHODS

Four databases were searched until Nov 2021. Randomized controlled trials (RCTs) and observational studies reporting liver-related outcomes following Food and Drug Administration (FDA)-approved and non-FDA-approved EBMTs were included. Liver parameters, metabolic parameters, and weight loss were evaluated. Risk of bias was assessed using the "risk of bias" tool in the Cochrane Collaboration for RCTs and the Methodological Index for Non-Randomized Studies criteria for observational studies.

RESULTS

Thirty-three studies with 1710 individuals were included. Regarding the effects of EBMTs on liver fibrosis, a significant decline of NAFLD Fibrosis Score, but not transient elastography-detected liver stiffness or Fibrosis-4 Index, was observed. EBMTs significantly improved liver steatosis (control attenuation parameter and Hepatic Steatosis Index), NAFLD Activity Score, and Homeostasis Model Assessment of Insulin Resistance. EBMTs reduced serum levels of alanine transaminase, aspartate aminotransferase, and gamma-glutamyl transpeptidase considerably. Moreover, EBMTs had reducing effects on the serum levels of triglycerides and total cholesterol as well as body weight.

CONCLUSIONS

Our meta-analysis suggested that EBMTs could ameliorate NAFLD based on the evidence of improved liver steatosis, liver function, and insulin resistance. Large-scale, prospective, long-term studies are warranted to clarify the role of EBMTs in patients with different stages of NAFLD.

Research Progress of Duodenal-Jejunal Bypass Liner in the Treatment of Obesity and Type 2 Diabetes Mellitus

With the development of economy and improvement of people's living standards, the incidence of obesity and type 2 diabetes mellitus (T2DM) has increased significantly and obesity has also become one of the most important risk factors of T2DM. In light of these trends, there have been many ways to take effect in losing weight. However, they also have corresponding deficiencies including inapparent curative effect, complex and incomplete reversible procedures and severe complications. Duodenal-Jejunal Bypass Liner (DJBL), which mimics Roux-en-Y gastric bypass (RYGB), is proved to play a key role in weight loss and control of T2DM. DJBL is reversible, less invasive and is more suitable for the treatment of obesity and T2DM, which is associated with multiple mechanisms, including incretin effect, gastric emptying mechanism, bile acid regulation, intestinal microbiota, inflammatory reaction mechanism and neural mechanism. In our review, we aimed to elaborate DJBL's clinical efficacy, safety and mechanisms in detail.

Personalized Approach for Obese Patients Undergoing Endoscopic Sleeve Gastroplasty

Obesity is a chronic, relapsing disease representing a major global health problem in the 21st century. Several etiologic factors are involved in its pathogenesis, including a Western hypercaloric diet, sedentariness, metabolic imbalances, genetics, and gut microbiota modification. Lifestyle modifications and drugs often fail to obtain an adequate and sustained weight loss. To date, bariatric surgery (BS) is the most effective treatment, but only about 1% of eligible patients undergo BS, partly because of its negligible morbidity and mortality. Endoscopic sleeve gastroplasty (ESG) is a minimally invasive, endoscopic, bariatric procedure, which proved to be safe and effective. In this review, we aim to examine evidence supporting the role of a personalized and multidisciplinary approach, guided by a multidisciplinary team (MDT), for obese patients undergoing ESG, from patient selection to long-term follow-up. The cooperation of different health professionals, including an endocrinologist and/or obesity medicine physician, a bariatric surgeon, an endoscopist experienced in bariatrics, a registered dietitian, an exercise specialist, a behaviour coach, a psychologist, and a nurse or physician extender, aims to induce radical and sustained lifestyle changes. We also discussed the relationship between gut microbiota and outcomes after bariatric procedures, speculating that the characterization of gut microbiota before and after ESG may help develop new tools, including probiotics, to optimize weight loss outcomes.

Shifts in gut microbiota and their metabolites induced by bariatric surgery. Impact of factors shaping gut microbiota on bariatric surgery outcomes

Evidence suggests that bariatric surgery alters gut microbiota, although its impact at compositional and functional level is not well described. In this review, the most relevant findings, mainly described in Roux-en-Y gastric bypass and sleeve gastrectomy, are outlined. Although the number of studies has increased in the last years, conclusive assertions cannot be elaborated. An issue to address is to know the influence of these alterations on host metabolism and the contribution of gut microbiota derived metabolites. New lines of research have been focusing on analysing gut microbiota functionality rather than evaluating changes at compositional level, and the functions of gut microbiota metabolites in host metabolism, what will bring more relevant information about the influence of gut microbiota in bariatric surgery outcomes. Personalized medicine, because of the predictive value of gut microbiota, is another promising field. The possibility of a specific gut microbiota pattern that could predict type 2 diabetes remission or weight loss failure after bariatric surgery is a matter of great interest. However, little is known about how gut microbiota manipulation could contribute to the beneficial effects of bariatric surgery. Peri-operative antibiotics prophylaxis or probiotic supplementation early after surgery, are strategies barely studied so far, and could constitute a novel tool in the management of weight loss and metabolic profile improvement after surgery.

Bariatric procedures and microbiota: patient selection and outcome prediction

Obesity is a major health issue throughout the world and bariatric surgery plays a key role in its management and treatment. The role of microbiota in determining the pathogenesis of obesity has been widely studied, while its role in determining the outcome of bariatric surgery is an emerging issue that will be an outcome in near future studies. Studies on mice first showed the key role of microbiota in determining obesity, highlighting the fat mass increase in mice transplanted with microbiota from fat individuals, as well as the different microbiota composition between mice undergone to low-fat or high-fat diets. This led to characterize the asset of microbiota composition in obesity: increased abundance of Firmicutes, reduced abundance of Bacteroidetes and other taxonomical features. Variations on the composition of gut microbiome have been detected in patients undergone to diet and/or bariatric surgery procedures. Patients undergone to restricting diets showed lower level of trimethylamine N-oxide and other metabolites strictly associated to microbiome, as well as patients treated with bariatric surgery showed, after the procedure, changes in the relative abundance of Bacteroidetes, Firmicutes and other phyla with a role in the pathogenesis of obesity. Eventually, studies have been led about the effects that the modification of microbiota could have on obesity itself, mainly focusing on elements like fecal microbiota transplantation and probiotics such as inulin. This series of studies and considerations represent the first step in order to select patients eligible to bariatric surgery and to predict their outcome.

Gut microbiota and metabolic syndrome

Metabolic syndrome (MetS) describes a set of risk factors that can eventually lead to the occurrence of cardiovascular and cerebrovascular disease. A detailed understanding of the MetS mechanism will be helpful in developing effective prevention strategies and appropriate intervention tools. In this article, we discuss the relationship between the clinical symptoms of MetS and differences in the gut microbial community compared with healthy individuals, characterized by the proliferation of potentially harmful bacteria and the inhibition of beneficial ones. Interactions between gut microbiota and host metabolism have been shown to be mediated by a number of factors, including inflammation caused by gut barrier defects, short-chain fatty acids metabolism, and bile acid metabolism. However, although we can clearly establish a causal relationship between gut microbial profiles and MetS in animal experiments, the relationship between them is still controversial in humans. Therefore, we need more clinical studies to augment our understanding of how we can manipulate the gut microbiota and address the role of the gut microbiota in the prevention and treatment of MetS.

The Role of duodenal jejunal bypass liner in obesity treatment

<abstract> <p>Endoscopic bariatric procedures including Duedenal Jejunal Bypass Liner (DJBL) have become widespread in obesity treatment in recent years. The aim of this systematic review was to assess the role of DJBL in obesity treatment. A comprehensive search of several databases, including Cochrane Library, PubMed, and Web of Science was conducted to December 2020. Twenty-four clinical studies were assessed. According to the results, it is clear that DJBL provides effective weight reduction at 6–12 months and significant improvements in parameters associated with metabolic syndrome and cardiovascular disease. This technique also has potential to reduce comedications in patients with obesity and type 2 diabetes. Although these positive effects of DJBL are clear, its effect on liver, pancreatic functions, and inflammation markers are not clear yet. In addition, the overall and serious complication (gastrointestinal bleeds, pancreatitis, hepatic abscess, obstruction of the sleeve, biliary colic without cholecystitis and cholangitis) rate causing from the DJBL is very high. DJBL has not been approved by the Food and Drug Administration due to the frequency and severity of complications it causes. While it is certain that DJBL has significant effects on obesity and obesity related comorbidities, the safety aspect needs to be improved.</p> </abstract>