The role of bile acids in reducing the metabolic complications of obesity after bariatric surgery: a systematic review

Stronger control of eating 3 months after sleeve gastrectomy predicts successful weight loss outcomes at one year

Background

Weight loss response to sleeve gastrectomy (SG) is variable and predicting the effectiveness of surgery is challenging and elusive. The aim of our study was to assess and quantify the association between eating control and weight loss outcomes and identify the control of eating (CoE) attributes during the early postoperative period that might predict good vs. poor response to SG at one year.

Methods

A prospective longitudinal cohort study using the Control of Eating Questionnaire (CoEQ) was designed as a series before and at 3-, 6-, and 12-months post-SG. Primary outcomes were changes in CoE attributes and percent of total weight loss (%TWL) 12-months post-surgery. Subjects were categorized based on %TWL as good (GR, ≥25 %) or poor responders (PR, <25 %). A receiver operating characteristic and logistic regression analyses were performed.

Results

We included 41 participants (80.5% females, 51.2% Hispanic, mean age 41.7±10.6, median baseline body mass index (BMI) 43.6 kg/m2 [range 35.2-66.3]) who completed the CoEQ at all four timepoints. The "Difficulty to control eating" score at 3 months revealed the highest area under the curve (AUC) (AUC 0.711; 95%CI 0.524-0.898; p=0.032). In a trade-off between a high Youden index and high sensitivity, the "Difficulty to control eating" score of 7 at 3 months was identified as the optimal cut-off for distinguishing between GRs and PRs. Score ≤7 at 3 months was strongly independently associated with a successful weight loss target of 25%TWL at one-year post-SG (Relative Risk 4.43; 95%CI 1.06-18.54; p=0.042).

Conclusion

"Difficulty to control eating" score at 3 months post-SG is an independent early predictor of optimal response (achieving a successful TWL target of ≥25 % at one-year post-SG). Our results support the utility of this easy-to-administer validated tool for predicting the effectiveness of SG and may assist in identifying individuals with suboptimal response early and helping them with interventions to attain optimal weight loss targets.

Effect of 1-year lifestyle intervention with energy-reduced Mediterranean diet and physical activity promotion on the gut metabolome and microbiota: a randomized clinical trial

BACKGROUND

The health benefits of the Mediterranean diet (MedDiet) have been linked to the presence of beneficial gut microbes and related metabolites. However, its impact on the fecal metabolome remains poorly understood.

OBJECTIVES

Our goal was to investigate the weight-loss effects of a 1-y lifestyle intervention based on an energy-reduced MedDiet coupled with physical activity (intervention group), compared with an ad libitum MedDiet (control group), on fecal metabolites, fecal microbiota, and their potential association with cardiovascular disease risk factors.

METHODS

A total of 400 participants (200 from each study group), aged 55-75 y, and at high cardiovascular disease risk, were included. Dietary and lifestyle information, anthropometric measurements, blood biochemical parameters, and stool samples were collected at baseline and after 1 y of follow-up. Liquid chromatography-tandem mass spectrometry was used to profile endogenous fecal metabolites, and 16S amplicon sequencing was employed to profile the fecal microbiota.

RESULTS

Compared with the control group, the intervention group exhibited greater weight loss and improvement in various cardiovascular disease risk factors. We identified intervention effects on 4 stool metabolites and subnetworks primarily composed of bile acids, ceramides, and sphingosines, fatty acids, carnitines, nucleotides, and metabolites of purine and the Krebs cycle. Some of these were associated with changes in several cardiovascular disease risk factors. In addition, we observed a reduction in the abundance of the genera Eubacterium hallii group and Dorea, and an increase in alpha diversity in the intervention group after 1 y of follow-up. Changes in the intervention-related microbiota profiles were also associated with alterations in different fecal metabolite subnetworks and some cardiovascular disease risk factors.

CONCLUSIONS

An intervention based on an energy-reduced MedDiet and physical activity promotion, compared with an ad libitum MedDiet, was associated with improvements in cardiometabolic risk factors, potentially through modulation of the fecal microbiota and metabolome. This trial was registered at https://www.isrctn.com/ as ISRCTN89898870 (https://doi.org/10.1186/ISRCTN89898870).

The emerging role of bile acids in white adipose tissue

The effects of bile acids (BAs) on liver, enteroendocrine function, small intestine, and brown adipose tissue have been described extensively. Outside the liver, BAs in the peripheral circulation system represent a specific but underappreciated physiological compartment. We discuss how systemic BAs can be regarded as specific steroidal hormones that act on white adipocytes, and suggest the name 'bilokines' ('bile hormones') for the specific FXR/TGR5 receptor interaction in adipocytes. Some BAs and their agonists regulate adipocyte differentiation, lipid accumulation, hypoxia, autophagy, adipokine and cytokine secretion, insulin signaling, and glucose uptake. BA signaling could provide a new therapeutic avenue for adipoflammation and metaflammation in visceral obesity, the causal mechanisms underlying insulin resistance and type 2 diabetes mellitus (T2D).

Micronutrients in Pregnancy after Bariatric Surgery: A Narrative Review

Bariatric surgery is increasingly used in women of childbearing age due to the rising prevalence of obesity and the effectiveness and availability of this treatment. Pregnancy in women with previous bariatric surgery deserves special attention. Weight loss induced by surgery reduces the risks that obesity poses to pregnancy. But on the other hand, decreased intake and malabsorption may increase the risk of malnutrition and micronutrient deficiency and negatively affect maternal and foetal health. The aim of this narrative review is to provide an updated analysis of the impact of different bariatric surgery techniques on mineral and micronutrient nutritional status during pregnancy and the possible effect on maternal-foetal health.

Understanding the Role of the Gut Microbiome in Diabetes and Therapeutics Targeting Leaky Gut: A Systematic Review

The gut microbiota has been studied and continues to be a developing area in the pathognomic development of metabolic diseases like diabetes. Treatment with diet changes, the addition of supplements like prebiotics/probiotics, and the impact of fecal microbial transplantation can be correlated to targeting changes in dysbiosis. Understanding the impacts of various anti-hyperglycemic agents such as metformin and the implications of post-bariatric surgery on the gut microbiota diversity has emerged. These areas of study are crucial to understanding the pathognomic aspects of diabetes disease progression at the microbial level of metabolic and inflammatory mechanisms, which may give more insight into focusing on the role of diet prebiotic/probiotic supplements as potential forms of prospective management in diabetes and the development of more agents that target gut microbiota, which harbors low-grade inflammation. Intestinal dysbiosis was consistently observed in the mechanism of gut microbial change in diabetic individuals, contributing to reduced insulin sensitivity and poor glycemic control. This systematic review was carried out using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) 2020 checklist. We performed a literature search using the PubMed, Google Scholar and Science Direct databases in accordance with the eligibility criteria and ultimately selected 14 articles for final analysis. The Scale for the Assessment of Narrative Review Articles (SANRA) and the PRISMA 2020 checklist were used to assess the quality of selected articles for cross-sectional studies, traditional literature reviews, and systematic reviews, respectively. We collected papers from 2012 to 2022 for this review. We gathered articles from databases, such as this study, which show there is a strong connection between microbiota and diabetes that appears to exist. The objective is to assess and identify any dietary and therapeutic agents that may alter the microbiota and potentially target and modulate insulin sensitivity. This review article will discuss the pathophysiological effects of gut microbiota in diabetes management and the impact of various gut biodiversity therapeutics that can aid in reversing insulin sensitivity.

Wen-Shen-Jian-Pi-Hua-Tan decoction protects against early obesity-related glomerulopathy by improving renal bile acid composition and suppressing lipogenesis, inflammation, and fibrosis

BACKGROUND

Obesity is an independent predictor of chronic kidney disease (CKD) development and may directly lead to kidney lesions such as obesity-related glomerulopathy (ORG) which might play a vital pathogenic role in obese patients with CKD. Wen-Shen-Jian-Pi-Hua-Tan decoction (WSHT) has been clinically used for the treatment of obesity and obesity-related metabolic diseases for years. However, the renoprotective effects and potential mechanism of action of WSHT against ORG remain unknown.

PURPOSE

This study aimed to explore the potential effect of WSHT on ORG and reveal its mechanisms in high-fat diet (HFD)-induced obese rats.

METHODS

An animal model of early stage ORG was established using HFD-induced obese rats. After treatment with WSHT for 6 weeks, an integrated metabolomics and molecular biology strategy was utilized to illustrate the effects and mechanism of WSHT on ORG. First, UPLC-ESI-MS/MS-based targeted metabolomics was used to analyze renal bile acid (BA) levels. Biochemical, histological, and immunofluorescence assays; electron microscopy; and western blotting were performed to evaluate the efficacy of WSHT against ORG and its underlying mechanisms in vivo.

RESULTS

Our results showed that an HFD led to hyperlipidemia, proteinuria, renal lipid deposition, effacement of podocyte foot processes, and increased expression of proinflammatory factors and profibrotic growth factors in ORG rats. In addition, an HFD decreased the levels of renal BAs such as cholic acid, chenodeoxycholic acid, and lithocholic acid. After 6 weeks of treatment, WSHT markedly attenuated dyslipidemia and reduced body, kidney and epididymal fat weights in ORG rats. WSHT also significantly increased BA levels, suggesting that it altered BA composition; the effects of BAs are closely associated with farnesoid X receptor (FXR) activation. WSHT alleviated fat accumulation, podocyte loss and proteinuria, and reduced the expression of proinflammatory cytokines and profibrotic growth factors in the kidneys of ORG rats. Finally, WSHT remarkably upregulated the renal expression of FXR and salt-induced kinase 1 and blocked the renal expression of sterol regulatory element-binding protein-1c and its target genes.

CONCLUSION

WSHT attenuated early renal lesions in ORG rats by improving renal BA composition and suppressing lipogenesis, inflammation and fibrosis. This study develops a new way to alleviate obesity-induced renal damages.

Metabolic Contributions to Pathobiology of Asthma

Asthma is a heterogenous disorder driven by inflammatory mechanisms that result in multiple phenotypes. Given the complex nature of this condition, metabolomics is being used to delineate the pathobiology of asthma. Metabolomics is the study of metabolites in biology, which includes biofluids, cells, and tissues. These metabolites have a vital role in a disease as they contribute to the pathogenesis of said condition. This review describes how macrometabolic and micrometabolic studies pertaining to these metabolites have contributed to our current understanding of asthma, as well as its many phenotypes. One of the main phenotypes this review will discuss in further detail is obesity as well as diabetes. Distinct roles of metabolites in endotyping asthma and their translation to potential therapy development for asthma is also discussed in this review.

Fecal Microbiota Transplantation in NAFLD Treatment

Introduction: Gut microbiota is not only a taxonomic biologic ecosystem but is also involved in human intestinal and extra-intestinal functions such as immune system modulation, nutrient absorption and digestion, as well as metabolism regulation. The latter is strictly linked to non-alcoholic fatty liver disease (NAFLD) pathophysiology. Materials and methods: We reviewed the literature on the definition of gut microbiota, the concepts of “dysbiosis” and “eubiosis”, their role in NAFLD pathogenesis, and the data on fecal microbiota transplantation (FMT) in these patients. We consulted the main medical databases using the following keywords, acronyms, and their associations: gut microbiota, eubiosis, dysbiosis, bile acids, NAFLD, and FMT. Results: Gut microbiota qualitative and quantitative composition is different in healthy subjects vs. NALFD patients. This dysbiosis is associated with and involved in NAFLD pathogenesis and evolution to non-acoholic steatohepatitis (NASH), liver cirrhosis, and hepatocellular carcinoma (HCC). In detail, microbial-driven metabolism of bile acids (BAs) and interaction with hepatic and intestinal farnesoid nuclear X receptor (FXR) have shown a determinant role in liver fat deposition and the development of fibrosis. Over the use of pre- or probiotics, FMT has shown preclinical and initial clinical promising results in NAFLD treatment through re-modulation of microbial dysbiosis. Conclusions: Promising clinical data support a larger investigation of gut microbiota dysbiosis reversion through FMT in NAFLD using randomized clinical trials to design precision-medicine treatments for these patients at different disease stages.

Multi-omic phenotyping reveals host-microbe responses to bariatric surgery, glycaemic control and obesity

Background

Resolution of type 2 diabetes (T2D) is common following bariatric surgery, particularly Roux-en-Y gastric bypass. However, the underlying mechanisms have not been fully elucidated.

Methods

To address this we compare the integrated serum, urine and faecal metabolic profiles of participants with obesity ± T2D (n = 80, T2D = 42) with participants who underwent Roux-en-Y gastric bypass or sleeve gastrectomy (pre and 3-months post-surgery; n = 27), taking diet into account. We co-model these data with shotgun metagenomic profiles of the gut microbiota to provide a comprehensive atlas of host-gut microbe responses to bariatric surgery, weight-loss and glycaemic control at the systems level.

Results

Here we show that bariatric surgery reverses several disrupted pathways characteristic of T2D. The differential metabolite set representative of bariatric surgery overlaps with both diabetes (19.3% commonality) and body mass index (18.6% commonality). However, the percentage overlap between diabetes and body mass index is minimal (4.0% commonality), consistent with weight-independent mechanisms of T2D resolution. The gut microbiota is more strongly correlated to body mass index than T2D, although we identify some pathways such as amino acid metabolism that correlate with changes to the gut microbiota and which influence glycaemic control.

Conclusion

We identify multi-omic signatures associated with responses to surgery, body mass index, and glycaemic control. Improved understanding of gut microbiota - host co-metabolism may lead to novel therapies for weight-loss or diabetes. However, further experiments are required to provide mechanistic insight into the role of the gut microbiota in host metabolism and establish proof of causality.

Weight-loss surgery is a highly effective treatment of type 2 diabetes in people with obesity. Interestingly, the improvement in diabetes after weight-loss surgery occurs before any significant weight-loss. Through better understanding of this metabolic improvement, weight-loss surgery provides a unique avenue to identify novel ways of treating diabetes and obesity. 

Here we combine measurements of metabolism, gut bacteria and diet in people with obesity, with or without type 2 diabetes and in patients before and after weight-loss surgery. We have used these data to identify changes associated with weight-loss surgery, obesity and diabetes. 

Improved understanding of the mechanisms behind these changes, including how changes to gut bacteria influence metabolism, may lead to new treatments for weight-loss or diabetes.

Penney et al. conduct microbial and metabolic profiling in people with obesity, with or without type 2 diabetes, undergoing two types of bariatric surgery. Integrative analysis identifies multi-omic signatures associated with response to surgery, body mass index, and glycaemic control.

Substantial Fat Loss in Physique Competitors Is Characterized by Increased Levels of Bile Acids, Very-Long Chain Fatty Acids, and Oxylipins

Weight loss and increased physical activity may promote beneficial modulation of the metabolome, but limited evidence exists about how very low-level weight loss affects the metabolome in previously non-obese active individuals. Following a weight loss period (21.1 ± 3.1 weeks) leading to substantial fat mass loss of 52% (−7.9 ± 1.5 kg) and low body fat (12.7 ± 4.1%), the liquid chromatography-mass spectrometry-based metabolic signature of 24 previously young, healthy, and normal weight female physique athletes was investigated. We observed uniform increases (FDR < 0.05) in bile acids, very-long-chain free fatty acids (FFA), and oxylipins, together with reductions in unsaturated FFAs after weight loss. These widespread changes, especially in the bile acid profile, were most strongly explained (FDR < 0.05) by changes in android (visceral) fat mass. The reported changes did not persist, as all of them were reversed after the subsequent voluntary weight regain period (18.4 ± 2.9 weeks) and were unchanged in non-dieting controls (n = 16). Overall, we suggest that the reported changes in FFA, bile acid, and oxylipin profiles reflect metabolic adaptation to very low levels of fat mass after prolonged periods of intense exercise and low-energy availability. However, the effects of the aforementioned metabolome subclass alteration on metabolic homeostasis remain controversial, and more studies are warranted to unravel the complex physiology and potentially associated health implications. In the end, our study reinforced the view that transient weight loss seems to have little to no long-lasting molecular and physiological effects.

Diagnostic Value of Bile Acids and Fibroblast Growth Factor 21 in Women with Polycystic Ovary Syndrome

Objective:

Polycystic ovary syndrome (PCOS) is a heterogeneous disorder characterized by a reduction in fertility and metabolic dysfunction. Unfortunately, due to a lack of clear presentation, it is often a long process of diagnosis. In this study, we investigated bile acids as potential biomarkers.

Materials and Methods:

Subjects were recruited and stratified into groups based on body mass index and PCOS status. Biometric data and plasma were acquired to understand bile acid profiles and related markers.

Results:

Taurocholic acid (TCA) and taurodeoxycholic acid were elevated in PCOS subjects with obesity in comparison to controls without PCOS. Fibroblast growth factor 21 (FGF-21), a metabolic regulator implemented in bile acid metabolism, was elevated in PCOS patients and was positively correlated with TCA changes.

Conclusions:

We present evidence suggesting that bile acids may be novel diagnostic targets in obese patients with PCOS while further studies need to delineate the interplay between FGF-21, bile acids, and testosterone in the early detection of PCOS.

Long-Term Trajectories in Weight and Health Outcomes Following Multidisciplinary Publicly Funded Bariatric Surgery in Patients with Clinically Severe Obesity (≥ 3 Associated Comorbidities): A Nine-Year Prospective Cohort Study in Australia

Background: Real-world data on long-term (> 5 years) weight loss and obesity-related complications after newer bariatric surgical procedures are currently limited. The aim of this longitudinal study was to examine the effectiveness and sustainability of bariatric surgery in a cohort with clinically severe obesity in a multidisciplinary publicly funded service in two teaching hospitals in New South Wales, Australia. Methods: Patients were adults with complex clinically severe obesity with a BMI ≥ 35 kg/m2 and at least three significant obesity-related comorbidities, who underwent bariatric surgeries between 2009 and 2017. Detailed obesity-related health outcomes were reported from annual clinical data and assessments for up to 9 years of follow-up. Data were also linked with the national joint replacement registry. Results: A total of 65 eligible patients were included (mean, 7; range, 3−12 significant obesity-related comorbidities); 53.8% female; age 54.2 ± 11.2 years, with baseline BMI 52.2 ± 12.5 kg/m2 and weight 149.2 ± 45.5 kg. Most underwent laparoscopic sleeve gastrectomy (80.0%), followed by laparoscopic adjustable gastric banding (10.8%) and one anastomosis gastric bypass (9.2%). Substantial weight loss was maintained over 9 years of follow-up (p < 0.001 versus baseline). Significant total weight loss (%TWL ± SE) was observed (13.2 ± 2.3%) following an initial 1-year preoperative intensive lifestyle intervention, and ranged from 26.5 ± 2.3% to 33.0 ± 2.0% between 1 and 8 years following surgery. Type 2 diabetes mellitus (T2DM), osteoarthritis-related joint pain and depression/severe anxiety were the most common metabolic, mechanical and mental health comorbidities, with a baseline prevalence of 81.5%, 75.4% and 55.4%, respectively. Clinically significant composite cumulative rates of remission and improvement occurred in T2DM (50.0−82.0%) and hypertension (73.7−82.9%) across 6 years. Dependence on continuous positive airway pressure treatment in patients with sleep-disordered breathing fell significantly from 63.1% to 41.2% in 6 years. Conclusion: Bariatric surgery using an intensive multidisciplinary approach led to significant long-term weight loss and improvement in obesity-related comorbidities among the population with clinically complex obesity. These findings have important implications in clinical care for the management of the highest severity of obesity and its medical consequences. Major challenges associated with successful outcomes of bariatric surgery in highly complex patients include improving mental health in the long run and reducing postoperative opioid use. Long-term follow-up with a higher volume of patients is needed in publicly funded bariatric surgery services to better monitor patient outcomes, enhance clinical data comparison between services, and improve multidisciplinary care delivery.

De Novo Inflammatory Bowel Disease Following Bariatric Surgery: a Systematic Review and Meta-analysis

The incidence of both obesity and inflammatory bowel disease (IBD) is rising globally. The influence of bariatric metabolic surgery (BMS) upon IBD development is largely unknown. This systematic review and meta-analysis aimed to evaluate the relationship between BMS and the risk of de novo IBD development following surgery. A systematic literature search and meta-analysis were performed using PubMed and Scopus databases. Inclusion criteria were any study reporting risk of de novo IBD development following BMS relative to an appropriate control cohort. Pooled odds ratios (POR) were calculated. A total of 31 articles were identified by the literature search. Four studies including 149,385 patients met the inclusion criteria and were included in the meta-analysis. Pooled estimation of a meta-analysis of risk ratios studies demonstrated a POR for the development of IBD following BMS of 1.17 (95% CI, 1.06-1.29). This indicates a 17% increase in relative risk of de novo IBD development for those patients receiving BMS compared to those treated by non-surgical methods. Based on the present data, there appears to be an association between BMS and risk of de novo IBD. Compared to the proven benefits of BMS on other aspects of patient health, this potential risk remains proportionally low but may be an important consideration for patients both pre- and post-operatively.

Reversal and Remission of T2DM - An Update for Practitioners

Over the past 50 years, many countries around the world have faced an unchecked pandemic of obesity and type 2 diabetes (T2DM). As best practice treatment of T2DM has done very little to check its growth, the pandemic of diabesity now threatens to make health-care systems economically more difficult for governments and individuals to manage within their budgets. The conventional view has been that T2DM is irreversible and progressive. However, in 2016, the World Health Organization (WHO) global report on diabetes added for the first time a section on diabetes reversal and acknowledged that it could be achieved through a number of therapeutic approaches. Many studies indicate that diabetes reversal, and possibly even long-term remission, is achievable, belying the conventional view. However, T2DM reversal is not yet a standardized area of practice and some questions remain about long-term outcomes. Diabetes reversal through diet is not articulated or discussed as a first-line target (or even goal) of treatment by any internationally recognized guidelines, which are mostly silent on the topic beyond encouraging lifestyle interventions in general. This review paper examines all the sustainable, practical, and scalable approaches to T2DM reversal, highlighting the evidence base, and serves as an interim update for practitioners looking to fill the practical knowledge gap on this topic in conventional diabetes guidelines.

The role of the colonic microbiota and bile acids in colorectal cancer

PURPOSE OF REVIEW

Colorectal cancer (CRC) is the third most common cancer and the second most common cause of cancer-related deaths. Of the various established risk factors for this aggressive condition, diet is a notable modifiable risk factor. This review aims to summarize the mounting evidence to suggest the role of diet, the microbiota and their cross-talk in modulating an individual's risk of developing CRC.

RECENT FINDINGS

Specifically, the metabolism of bile acids and its symbiosis with the microbiota has gained weight given its basis on a high meat, high fat, and low fibre diet that is present in populations with the highest risk of CRC. Bacteria modify bile acids that escape enterohepatic circulation to increase the diversity of the human bile acid pool. The production of microbial bile acids contributes to this as well. Epidemiological studies have shown that changing the diet results in different levels and composition of bile acids, which has in turn modified the risk of CRC at a population level. Evidence to identify underlying mechanisms have tied into the microbiota-led digestions of various foods into fatty acids that feedback into bile acid physiology as well as modulation of endogenous receptors for bile acids.

SUMMARY

There is adequate evidence to support the role of microbiota in in the metabolism of bile acids, and how this relates to colorectal cancer. Further work is necessary to identify specific bacteriome involved and their underlying mechanistic pathways.

Taurodeoxycholic acid and valine reverse obesity-associated augmented alloimmune responses and prolong allograft survival

Obesity initiates a chronic inflammatory network linked to perioperative complications and increased acute rejection rates in organ transplantation. Bariatric surgery is the most effective treatment of obesity recommended for morbidly obese transplant recipients. Here, we delineated the effects of obesity and bariatric surgery on alloimmunity and transplant outcomes in diet-induced obese (DIO) mice. Allograft survival was significantly shorter in DIO-mice. When performing sleeve gastrectomies (SGx) prior to transplantation, we found attenuated T cell-derived alloimmune responses resulting in prolonged allograft survival. Administering taurodeoxycholic acid (TDCA) and valine, metabolites depleted in DIO-mice and restored through SGx, prolonged graft survival in DIO-mice comparable with SGx an dampened Th1 and Th17 alloimmune responses while Treg frequencies and CD4+ T cell-derived IL-10 production were augmented. Moreover, in recipient animals treated with TDCA/valine, levels of donor-specific antibodies had been reduced. Mechanistically, TDCA/valine restrained inflammatory M1-macrophage polarization through TGR5 that compromised cAMP signaling and inhibited macrophage-derived T cell activation. Consistently, administering a TGR5 agonist to DIO-mice prolonged allograft survival. Overall, we provide novel insights into obesity-induced inflammation and its impact on alloimmunity. Furthermore, we introduce TDCA/valine as a noninvasive alternative treatment for obese transplant patients.

Resistant starch wheat increases PYY and decreases GIP but has no effect on self-reported perceptions of satiety

Dietary fiber has numerous health benefits, such as increasing satiety, and is regularly included in healthy dietary recommendations. However, different types and sources of fiber vary in their chemical properties and biological effects. This double-blind, randomized, placebo-controlled, crossover study investigated the effects of resistant starch type 2 (RS2) from wheat on self-reported perceptions of satiety and associated gut hormones in 30 healthy adults ages 40-65 years of age. Participants consumed rolls made using either RS2-enriched wheat flour or a wild-type flour for one week before a test day during which they ate a mixed meal containing the same roll type. Both self-reported perceptions of satiety and plasma concentrations of gut hormones were measured following the meal to assess whether the RS2-enriched wheat enhanced satiety and suppressed hunger for a longer period than the control wheat. Exploratory analysis indicated that fasting and peak concentration of peptide YY_3-36 (PYY_3-36; q_fast = 0.02, q_peak = 0.02) increased, while peak concentration and iAUC of glucose-dependent insulinotropic peptide (GIP; q_peak < 0.001, q_iAUC < 0.001) decreased after ingesting RS2-enriched wheat. However, self-reported perceptions of hunger or fullness using visual analog scales (VAS) did not differ following the test meal.

Food Taste, Dietary Consumption, and Food Preference Perception of Changes Following Bariatric Surgery in the Saudi Population: A Cross-Sectional Study

Background: Bariatric surgery is known as the most effective treatment resulting in long-term weight loss for obesity. However, behavioral changes, including food preference, food allergies, and consumption, between groups of patients who underwent bariatric surgery in comparison with people who did not have bariatric surgery have not been fully discussed in the literature. Objective: The aim of this article is to describe patient-reported changes of perception related to food preferences, consumption, and food allergies in participants who underwent bariatric surgery and to compare their food consumption with participants who did not have bariatric surgery in Saudi Arabia. Methodology: This study is a secondary analysis of the Sharik Diet and Health National Survey (SDHNS) conducted in July 2021. Quota sampling was utilized to generate balanced distributions of participants by age and gender across all administrative regions of Saudi Arabia. Data collection included sociodemographic information (age, gender, and educational level), as well as food habits and the consumption of various food categories. Results: Of the 6267 potential participants contacted in 2021 from the 13 administrative regions of Saudi Arabia, 5228 successfully completed the interview, with a response rate of 83.4%. Gender was distributed equally among the total participants in the sample. The prevalence of bariatric surgeries in Saudi Arabia was estimated at around 4.1% of the total sample. More than 36% of people who had bariatric surgery experienced food taste changes, and around 15% reported a decrease in allergic reactions to food. Moreover, 68.1% had food preference changes, either starting to favor a new food or no longer favoring one. There was a significant association between consuming more red meat, chicken, and energy drinks and a decreased consumption of grains and rice among those who had the bariatric surgery compared with those who did not. Conclusions: This study found that more than two-thirds of people who had bariatric surgery self-reported food taste and food preference changes. More studies should be performed on the Saudi population, including clinical follow-up, to better understand these changes.

Factors associated with resolution of type-2 diabetes mellitus after sleeve gastrectomy in obese adults

Many bariatric procedures are more effective for improving type-2 diabetes mellitus (T2DM) than conventional pharmacotherapy. The current research evaluated factors linked to complete and partial remission or improvement of T2DM after laparoscopic sleeve gastrectomy (LSG). The current prospective study included all diabetic patients who were submitted LSG between January 2015 and June 2018 and completed a 2-year follow-up period. Patients were assessed at baseline and 2 years after LSG. This work comprised of 226 diabetic cases. Two years after LSG, 86 patients (38.1%) achieved complete remission of DM, and 24 (10.6%) reached partial remission. Only 14 patients (6.2%) showed no change in their diabetic status. On univariate analysis, age ≤ 45 years, duration of diabetes ≤ 5 years, use of a single oral antidiabetic, HbA1c ≤ 6.5%, HOMA-IR ≤ 4.6, C-peptide > 2.72 ng/mL, and BMI ≤ 40 kg/m² predicted complete remission. The independent predictors of complete remission were age ≤ 45 years, duration of diabetes ≤ 5 years, use of a single oral antidiabetic, HOMA-IR ≤ 4.6, and C-peptide > 2.72 ng/mL. A combined marker of young age, short duration of DM, and low HOMA-IR predicted complete remission with sensitivity 93% and specificity 82%. Independent predictors of complete remission of T2DM after LSG were younger age, shorter duration, single oral antidiabetic, lower HOMA-IR, and higher C-peptide.

Serum Levels and Adipose Tissue Gene Expression of Cathelicidin Antimicrobial Peptide (CAMP) in Obesity and During Weight Loss

CAMP (Cathelicidin antimicrobial peptide) is synthesized and secreted by adipocytes and involved in adipose tissue (AT) innate immune response and host defense of subcutaneous AT against Gram positive bacteria. Data on the regulation of CAMP in obesity and during weight loss are scarce and reference values do not exist. Serum CAMP levels (ELISA) and AT gene expression levels (quantitative real time PCR) were investigated in two large and longitudinal (12 months) cohorts of severely obese patients undergoing either a low calorie diet (LCD; n=79) or bariatric surgery (BS; n=156). The impact of metabolic factors on CAMP expression in vitro was investigated in differentiated 3T3-L1 adipocytes. CAMP serum levels significantly increased after BS but not during LCD. Females had lower CAMP serum levels and lower gene expression levels in subcutaneous AT. CAMP was positively correlated to unfavorable metabolic factors/adipokines and negatively to favorable factors/adipokines. CAMP gene expression was higher in subcutaneous than in visceral AT but serum CAMP levels were not correlated to levels of AT gene expression. While certain bile acids upregulated CAMP expression in vitro, high glucose/insulin as well as GLP-1 had an inhibitory effect. There exist gender-specific and AT compartment-specific effects on the regulation of CAMP gene expression. Weight loss induced by BS (but not by LCD) upregulated CAMP serum levels suggesting the involvement of weight loss-independent mechanisms in CAMP regulation such as bile acids, incretins and metabolic factors. CAMP might represent an adipokine at the interface between metabolism and innate immune response.

Modulating the Gut Microbiota of Humans by Dietary Intervention with Plant Glycans

The human colon contains a community of microbial species, mostly bacteria, which is often referred to as the gut microbiota. The community is considered essential to human well-being by conferring additional energy-harvesting capacity, niche exclusion of pathogens, and molecular signaling activities that are integrated into human physiological processes. Plant polysaccharides (glycans, dietary fiber) are an important source of carbon and energy that supports the maintenance and functioning of the gut microbiota. Therefore, the daily quantity and quality of plant glycans consumed by the human host have the potential to influence health. Members of the gut microbiota differ in ability to utilize different types of plant glycans. Dietary interventions with specific glycans could modulate the microbiota, counteracting ecological perturbations that disrupt the intricate relationships between microbiota and host (dysbiosis). This review considers prospects and research options for modulation of the gut microbiota by the formulation of diets that, when consumed habitually, would correct dysbiosis by building diverse consortia that boost functional resilience. Traditional "prebiotics" favor bifidobacteria and lactobacilli, whereas dietary mixtures of plant glycans that are varied in chemical complexity would promote high-diversity microbiotas. It is concluded that research should aim at improving knowledge of bacterial consortia that, through shared nourishment, degrade and ferment plant glycans. The consortia may vary in composition from person to person, but functional outputs will be consistent in a given context because of metabolic redundancy among bacteria. Thus, the individuality of gut microbiotas could be encompassed, functional resilience encouraged, and correction of dysbiosis achieved.

Bariatric Surgical Alterations in Tolerability, Enjoyment and Cravings in the Diet (BSATED) instrument: A new scale to measure food preferences following bariatric surgery

Bariatric surgery is associated with changing food preferences, but it is not known whether these changes differ by type of operation or are associated with weight loss. The current study presents validation results for a new 27-item scale, Bariatric Surgical Alterations in Tolerability, Enjoyment and Cravings in the Diet (BSATED). This scale measured enjoyment, craving, and intolerance changes for nine food and beverage categories common to dietary habits in the Southern California region of the U.S. one year following bariatric surgery in the Bariatric Experience Long Term (BELONG) study. Validation of BSATED was done using exploratory factor analyses, construct validity with other conceptually related survey instruments, and criterion validity using hypothesized differences for operation type and percent total weight loss (%TWL) at 12-18 months after surgery. Participants (n = 999) were 86% female, 41% non-Hispanic White, with a mean age of 43.1 ± 11.3 years and a body mass index (BMI) of 43.4 ± 6.8 kg/m² at the time of surgery. Participants reported less enjoyment and craving for high-fat meats (62%), grains (54%), candy and other desserts (e.g. candy bars, chocolate, ice cream) (52%), and sweet baked goods (48%) 12 months after surgery. These changes were more common among participants undergoing Roux-en-Y gastric bypass (RYGB) compared to those receiving sleeve gastrectomy (SG). Participants who reported decreased enjoyment and craving for foods and beverages that post-bariatric patients are counseled to reduce or avoid had greater %TWL at 12-18 months following surgery (p < .001 and p = .003 respectively). The foods and beverages in BSATED that post-bariatric patients are counseled to reduce or avoid could be used to understand how changes in enjoyment, craving and tolerability of these foods/beverages contribute to weight loss following surgery.

A Subset of Roux-en-Y Gastric Bypass Bacterial Consortium Colonizes the Gut of Nonsurgical Rats without Inducing Host-Microbe Metabolic Changes

Roux-en-Y gastric bypass (RYGB) is an effective weight loss surgery, resulting in a characteristic increase of fecal Gammaproteobacteria The contribution of this compositional change to metabolic benefits of RYGB is currently debatable. Therefore, this study employed 16S rRNA gene sequencing and metabolic profiling to monitor the dynamic colonization of the RYGB microbial consortium and their metabolic impact on the host. Eleven Wistar rats received vancomycin and enrofloxacin, followed by fecal microbiota transplantation (FMT) of cecal slurry obtained from either RYGB- or sham-operated rats. Urine and feces from the microbiota recipients (RYGB microbiota recipients [RYGBr], n = 6; sham microbiota recipients [SHAMr], n = 5) were collected pre- and post-antibiotics and 1, 3, 6, 9, and 16 days post-FMT. No significant differences in body weight and food intake were observed between RYGBr and SHAMr. While neither group reached the community richness of that of their donors, by day 6, both groups reached the richness and diversity of that prior to antibiotic treatment. However, the typical signature of RYGB microbiome-increased Enterobacteriaceae-was not replicated in these recipients after two consecutive FMT, suggesting that the environmental changes induced by the anatomical rearrangements of RYGB could be key for sustaining such a consortium. The transplanted bacteria did not induce the same metabolic signature of urine and feces as those previously reported in RYGB-operated rats. Future work is required to explore environmental factors that shape the RYGB microbiota in order to further investigate the metabolic functions of the RYGB microbiota, thereby teasing out the mechanisms of the RYGB surgery.IMPORTANCE Roux-en-Y gastric bypass (RYGB) surgery results in a long-term gut bacterial shift toward Gammaproteobacteria in both patients and rodents. The contribution of this compositional shift, or the RYGB bacterial consortium, to the metabolic benefit of the surgery remains debatable. It is unclear how well these bacteria colonize in an anatomically normal gut. This is a fundamental question in both defining the function of the RYGB microbiota and evaluating its potential as a nonsurgical treatment for obesity. We monitored the dynamic colonization of the RYGB bacterial consortium and observed that while approximately one-third of the bacterial taxa from the RYGB donor colonized in the gut of the nonoperated recipients, Gammaproteobacteria were unable to colonize for longer than 3 days. The study highlighted that a successful long-term colonization of Gammaproteobacteria-rich RYGB microbiota in nonsurgical animals requires key environmental factors that may be dictated by the intestinal anatomical modification by the surgery itself.

The effect of Roux-en-Y gastric bypass in the treatment of hypertension and diabetes

INTRODUCTION

obesity has become a public health problem in Brazil and worldwide, due to its high prevalence. It is considered a risk factor for systemic arterial hypertension (SAH) and type 2 diabetes mellitus T2DM. Although lifestyle changes can control and even achieve complete T2DM remission, most patients have difficulty controlling blood glucose. Recent studies show that the Roux-en-Y gastric bypass (RYGB) is efficient for weight loss and control of T2DM and SAH in obese individuals.

OBJECTIVE

to analyze the effect of the RYGB technique on the control and treatment of comorbidities related to obesity.

METHOD

this is a retrospective cohort study, with information obtained from the review of medical records, with data collection in the pre and postoperative period of patients undergoing bariatric surgery. We selected those with T2DM and SAH for the study.

RESULTS

252 patients underwent RYGB in the service. Seventy-nine (31.3%) had T2DM and 64 had SAH associated with T2DM. Regarding T2DM and SAH, 37.9% and 43,7%, respectively, showed total remission of the disease after surgery. There was a reduction in the postoperative use of Metformin, insulin / Gliclazide, Propranolol, Losartan and Hydrochlorothiazide in 62%, 10.1%, 100%, 26.5% and 22.8% of patients, respectively.

CONCLUSION

the RYGB technique is effective in the remission of T2DM and SAH. Even in cases where there was no total remission of the diseases, there was a significant drop in the use of medicines used for their treatment.

Endocannabinoid Receptor-1 and Sympathetic Nervous System Mediate the Beneficial Metabolic Effects of Gastric Bypass

The exact mechanisms underlying the metabolic effects of bariatric surgery remain unclear. Here, we demonstrate, using a combination of direct and indirect calorimetry, an increase in total resting metabolic rate (RMR) and specifically anaerobic RMR after Roux-en-Y gastric bypass (RYGB), but not sleeve gastrectomy (SG). We also show an RYGB-specific increase in splanchnic sympathetic nerve activity and "browning" of visceral mesenteric fat. Consequently, selective splanchnic denervation abolishes all beneficial metabolic outcomes of gastric bypass that involve changes in the endocannabinoid signaling within the small intestine. Furthermore, we demonstrate that administration of rimonabant, an endocannabinoid receptor-1 (CB1) inverse agonist, to obese mice mimics RYGB-specific effects on energy balance and splanchnic nerve activity. On the other hand, arachidonoylethanolamide (AEA), a CB1 agonist, attenuates the weight loss and metabolic signature of this procedure. These findings identify CB1 as a key player in energy regulation post-RYGB via a pathway involving the sympathetic nervous system.

Changes in Body Composition and Biochemical Parameters Following Laparoscopic One Anastomosis Gastric Bypass: 1-Year Follow-Up

BACKGROUND/AIM

Little data is available on body composition and biochemical parameter changes after one anastomosis gastric bypass (OAGB) surgery. This study was therefore conducted to assess body composition and biochemical parameter changes in patients who underwent OAGB. The relationship between the percentage of total weight loss (%TWL) with percentage changes in body composition and biochemical parameters was measured in the first year after surgery.

MATERIALS AND METHODS

This retrospective study was carried out on 363 patients (mean age 39.93 ± 9.98 years) who underwent OAGB between January 2011 and November 2018. Anthropometric, body composition and biochemical measurements were recorded before and 1 year after surgery. For paired data, a paired sample t test or Wilcoxon test was used. Spearman or Pearson correlation test was used to evaluate the relationship between % TWL and changes in body composition and biochemical parameters.

RESULTS

The average %TWL at 1 year following surgery was 35.72 ± 6.85. Fat and muscle tissue and also serum levels of glycemic parameters, low density lipoprotein, triglycerides (TG), total cholesterol, zinc, albumin, hemoglobin, hematocrit, and platelet had decreased a year after OAGB (P < 0.05). The postoperative levels of HDL-c, vitamins D, B12, and folic acid were dramatically higher than the preoperative values. Higher %TWL significantly correlated to greater decreases in body fat, muscle mass, and serum TG at 1 year post-surgery, compared to preoperative values.

CONCLUSION

OAGB may be effective over a follow-up period of 1 year in achieving weight, fat mass reduction, and improved serum levels of glycemic parameters and lipid profiles.

Effects of laparoscopic sleeve gastrectomy on concentration and composition of bile acids in an Asian population with morbid obesity

Background:

Bile acids (BAs) are traditionally associated with lipid absorption and phase II detoxification by forming various BA conjugates. Recently, it has been discovered that BAs also regulate glucose metabolism, and the increase in BAs in patients following bariatric surgery may contribute to the post-surgery improvement in insulin resistance (IR). However, while Roux-en-Y gastric bypass can increase BA concentrations post-surgery, this may not be the case after laparoscopic sleeve gastrectomy (LSG). We hypothesized that the profiling of BAs that include the conjugated BA species could detect post-surgery BA changes after LSG. To test our hypothesis, we performed comprehensive profiling of BAs in Asian individuals with morbid obesity at baseline, and at 6 months following LSG.

Methods:

Fourteen subjects scheduled for LSG were recruited. Anthropometric measurements, oral glucose tolerance test, and biochemistry tests were performed at baseline and at 6 months after LSG. BAs were profiled using liquid chromatography–mass spectrometry.

Results:

At 6 months, subjects lost significant weight from 117.4±5.4 to 92.1±3.8 kg and demonstrated significant improvement in IR. HOMA-IR decreased from 6.2±0.7 to 2.0±0.2 and the Matsuda index increased from 1.9±0.3 to 3.3±0.3. We did not detect any significant post-operative change in the levels of total BAs (5237.1±1219.4 vs. 3631.7±457.9, p=0.181) or non-sulfated BAs after LSG. However, sulfated BA species increased significantly after LSG.

Conclusion:

Our study showed that the serum concentrations of sulfated BA species in morbidly obese Asian individuals increased significantly 6 months after LSG; the increase in sulfated BAs after LSG might contribute to the post-surgery improvement of metabolic health.

Ruggedness testing of liquid chromatography-tandem mass spectrometry system components using microbiome-relevant methods and matrices

Recently, an opportunity to perform a broad ruggedness assessment of our liquid chromatography-tandem mass spectrometry (LC-MS/MS) system presented itself during the analytical planning phase of a large-scale human fecal microbiome study. The specific aim of this project was to study the microbial-mediated metabolism of a targeted set of bile acids/salts by mixed bacterial communities cultured from the feces of 12 healthy volunteers when grown in a custom growth medium and following exposure to different clinically-relevant antibiotics. The magnitude of this study offered a rare opportunity to significantly stress procedures and LC-MS/MS system components comprised in our bile acid/salt targeted metabolomics method. With this second specific aim in mind, we modified the sample analysis plan to include a series of figure-of-merit (FoM)-based tests that are commonly used in regulated bioanalytical labs to assess LC and MS system ruggedness for a specific assay - these FoM-based testing parameters were monitored continuously over the course of sample analysis and the results are presented in this report. In total, the assessment included 1206 sequential injections (180 calibration standards, 136 blank-internal standard samples, and 890 diluted medium samples) that took place over 8-days. Completion of the 8-days of non-stop sample analysis revealed no critical hardware or software failures, and the analysis of the FoM-based tests indicated no observable degradation of system performance over the number of samples and time tested. The FoM-based test metrics presented may be used as a template to assess the ruggedness of any LC-MS/MS-based targeted metabolomics workflow.

Cholecystectomy - a potential selection bias in studies assessing the metabolic effects of bariatric surgeries

Bile acids (BAs) are key mediators of the glycemic control after bariatric surgeries. Cholecystectomy modifies the kinetics of BAs, and whether this procedure influences the BAs pool and its metabolic response to bariatric surgeries is not known. We used targeted and untargeted metabolomics to assess whether cholecystectomy influenced plasma and fecal BAs fluctuations and the systemic metabolomic profile after Roux-en-Y gastric bypass (RYGB). Women with obesity and type 2 diabetes were included. Sample collections and clinical evaluations were performed before and 3 months after RYGB. RYGB influenced 9 fecal and 3 plasma BAs in patients with cholecystectomy (p ≤ 0.05). Comparisons between patients with and without cholecystectomy revealed different concentrations of 4 fecal and 5 plasma BAs (p ≤ 0.05). Cholecystectomy impacted the global metabolomics responses to RYGB, and patients who underwent the gallbladder removal also lacked some significant improvements in clinical markers, primarily the lipid profile. By affecting the BAs concentrations, cholecystectomy seems to alter the systemic metabolic response to RYGB. Therefore, cholecystectomy may act as a bias in assessments of the metabolic effects of bariatric surgeries and their relationships with clinical outcomes.

Changes in Gut Microbiota and Hormones After Bariatric Surgery: a Bench-to-Bedside Review

Overweight and obesity are among the most prevalent non-communicable diseases which are generally treated successfully by bariatric or sleeve surgery. There are evidences affirming that sleeve surgery can manipulate the pH of the stomach and interact with the metabolism of fatty acids, carbohydrates, and bile acid transfer, leading to the overgrowth of gut microbiota. Therefore, this study aims to review the changes in gut microbiota and hormones after bariatric surgery.

Cancer Risk Following Bariatric Surgery-Systematic Review and Meta-analysis of National Population-Based Cohort Studies

This study has analyzed results from registry-based population studies to assess the effect of bariatric surgery upon cancer incidence at a population level. Relevant studies were identified and meta-analysis was used to calculate pooled odds ratios (POR) for the incidence of cancer after bariatric surgery compared to controls. Eight population-based studies were included with 635,642 total patients. Bariatric surgery was associated with a significant reduction in overall cancer incidence (POR = 0.72; 95% CI 0.59 to 0.87; p = 0.0007) and incidence of obesity-related cancer (POR = 0.55; 95% CI 0.31 to 0.96; p = 0.04). Bariatric surgery was also protective for breast cancer development (POR = 0.50; 95% CI 0.25 to 0.99; p = 0.045). Bariatric surgery appears to be associated with a reduction in cancer incidence at a population-based level.

Gut Peptide Agonism in the Treatment of Obesity and Diabetes

Obesity is a global healthcare challenge that gives rise to devastating diseases such as the metabolic syndrome, type-2 diabetes (T2D), and a variety of cardiovascular diseases. The escalating prevalence of obesity has led to an increased interest in pharmacological options to counteract excess weight gain. Gastrointestinal hormones such as glucagon, amylin, and glucagon-like peptide-1 (GLP-1) are well recognized for influencing food intake and satiety, but the therapeutic potential of these native peptides is overall limited by a short half-life and an often dose-dependent appearance of unwanted effects. Recent clinical success of chemically optimized GLP-1 mimetics with improved pharmacokinetics and sustained action has propelled pharmacological interest in using bioengineered gut hormones to treat obesity and diabetes. In this article, we summarize the basic biology and signaling mechanisms of selected gut peptides and discuss how they regulate systemic energy and glucose metabolism. Subsequently, we focus on the design and evaluation of unimolecular drugs that combine the beneficial effects of selected gut hormones into a single entity to optimize the beneficial impact on systems metabolism. © 2020 American Physiological Society. Compr Physiol 10:99-124, 2020.

Metabolic phenotyping of the human microbiome

The human microbiome has been identified as having a key role in health and numerous diseases. Trillions of microbial cells and viral particles comprise the microbiome, each representing modifiable working elements of an intricate bioactive ecosystem. The significance of the human microbiome as it relates to human biology has progressed through culture-dependent (for example, media-based methods) and, more recently, molecular (for example, genetic sequencing and metabolomic analysis) techniques. The latter have become increasingly popular and evolved from being used for taxonomic identification of microbiota to elucidation of functional capacity (sequencing) and metabolic activity (metabolomics). This review summarises key elements of the human microbiome and its metabolic capabilities within the context of health and disease.

Anti-incretin effect: The other face of Janus in human glucose homeostasis

The provocative idea that type 2 diabetes (T2D) may be a surgically treated disorder is based on accumulating evidence suggesting impressive remission rates of obesity and diabetes following bariatric surgery interventions. According to the "anti-incretin" theory, ingestion of food in the gastrointestinal (GI) tract, apart from activating the well-described incretin effect, also results in the parallel stimulation of a series of negative feedback mechanisms (anti-incretin effect). The primary goal of these regulations is to counteract the effects of incretins and other postprandial glucose-lowering adaptive mechanisms. Disruption of the equilibrium between incretins and anti-incretins could be an additional pathway leading to the development of insulin resistance and hyperglycemia. This theory provides an alternative theoretical framework to explain the mechanisms behind the optimal effects of metabolic surgery on T2D and underlines the importance of the GI tract in the homeostatic regulation of energy balance in humans. The anti-incretin concept is currently based on a limited amount of evidence and certainly requires further validation by additional studies. The aim of the present review is to discuss and critically evaluate recent evidence on the anti-incretin theory, providing an insight into current state and future perspectives.

Mechanisms of Weight Loss After Sleeve Gastrectomy and Adjustable Gastric Banding: Far More Than Just Restriction

Obesity has reached global epidemic proportions in recent decades. Bariatric surgery is currently accepted as most effective in alleviating morbid obesity and related disorders. Sleeve gastrectomy (SG) and adjustable gastric banding (AGB) have gained popularity since the beginning of this century because of their efficacy, safety, and simplicity. SG, in particular, has emerged as the most popular bariatric procedure because of its simpler concept and shorter operative time compared with gastric bypass. Caloric restriction, however, cannot account for the sustained weight loss and improved glucose metabolism seen following SG and AGB. Other mechanisms, including changes in gastrointestinal hormone secretion, rearrangement of hypothalamic and vagal control, alteration in energy expenditure, and re-regulation of bile acid metabolism and the intestinal flora environment, are thought to contribute to the postoperative benefits. This review focuses on clinical and experimental literature addressing the potential mechanisms for SG and AGB procedures in human and animal models. Understanding such mechanisms can provide important insight into how current gastric restrictive procedures work and how future treatments of obesity, both surgical and nonsurgical, can be developed.

Metabolic Surgery and Diabesity: a Systematic Review

Bariatric surgery is used to induce weight loss (baros = weight). Evidence has shown that bariatric surgery improves the comorbid conditions associated with obesity such as hypertension, hyperlipidemia, and type 2 diabetes mellitus T2DM. Hence, shifting towards using metabolic surgery instead of bariatric surgery is currently more appropriate in certain subset of patients. Endocrine changes resulting from operative manipulation of the gastrointestinal tract after metabolic surgery translate into metabolic benefits with respect to the comorbid conditions. Other changes include bacterial flora rearrangement, bile acids secretion, and adipose tissue effect. The aim of this systematic review is to examine clinical trials regarding long-term effects of bariatric and metabolic surgery on patients with T2DM and to evaluate the potential mechanisms leading to the improvement in the glycaemic control.

Gut microbiota adaptation after weight loss by Roux-en-Y gastric bypass or sleeve gastrectomy bariatric surgeries

BACKGROUND

Gut microbiota could be involved in the metabolic improvement after surgery.

OBJECTIVE

The aim of the present study was to evaluate the short-term evolution of the gut microbiome after different bariatric surgery procedures and their functionality and relate it with obesity resolution.

SETTING

University hospital, Spain.

METHODS

We studied 28 patients with severe obesity; 14 underwent a Roux-en-Y gastric bypass (RYGB) and 14 underwent laparoscopic sleeve gastrectomy (SG). All patients were examined before and 3 months after the correspondent bariatric surgery. Gut microbiome profile was assessed by the sequencing of amplicons from the 16S rDNA gene by next-generation sequencing.

RESULTS

Gut microbiota profiles significantly differed between surgical procedures. RYGB suffered the largest changes in the microbiota population. SG and RYGB differed in their profiles with higher levels of Akkermansia, Eubacterium, Haemophilus, and Blautia for SG, while Veillonella, Slackia, Granucatiella, and Acidaminococcus occurred with greater levels in RYGB. RYGB microbiota changes were reflected also at the level of functionality, especially in pathways related to environmental adaptation. A biomarker discovery analysis revealed the genus Blautia as characteristic in SG, while Veillonella was of RYGB.

CONCLUSION

Our study shows a shift of the gut microbiome after a bariatric surgery in a procedure-related manner. Gut microbiome changes are related to the adaptation to the changing gut environment and could be related to the pH fluctuations.

Ozone-induced changes in the serum metabolome: Role of the microbiome

Ozone is an asthma trigger. In mice, the gut microbiome contributes to ozone-induced airway hyperresponsiveness, a defining feature of asthma, but the mechanistic basis for the role of the gut microbiome has not been established. Gut bacteria can affect the function of distal organs by generating metabolites that enter the blood and circulate systemically. We hypothesized that global metabolomic profiling of serum collected from ozone exposed mice could be used to identify metabolites contributing to the role of the microbiome in ozone-induced airway hyperresponsiveness. Mice were treated for two weeks with a cocktail of antibiotics (ampicillin, neomycin, metronidazole, and vancomycin) in the drinking water or with control water and then exposed to air or ozone (2 ppm for 3 hours). Twenty four hours later, blood was harvested and serum analyzed via liquid-chromatography or gas-chromatography coupled to mass spectrometry. Antibiotic treatment significantly affected 228 of the 562 biochemicals identified, including reductions in the known bacterially-derived metabolites, equol, indole propionate, 3-indoxyl sulfate, and 3-(4-hydroxyphenyl)propionate, confirming the efficacy of the antibiotic treatment. Ozone exposure caused significant changes in 334 metabolites. Importantly, ozone-induced changes in many of these metabolites were different in control and antibiotic-treated mice. For example, most medium and long chain fatty acids declined by 20-50% with ozone exposure in antibiotic-treated but not control mice. Most taurine-conjugated bile acids increased with ozone exposure in antibiotic-treated but not control mice. Ozone also caused marked (9-fold and 5-fold) increases in the polyamines, spermine and spermidine, respectively, in control but not antibiotic-treated mice. Each of these metabolites has the capacity to alter airway responsiveness and may account for the role of the microbiome in pulmonary responses to ozone.

Acute Changes of Bile Acids and FGF19 After Sleeve Gastrectomy and Roux-en-Y Gastric Bypass

CONTEXT

Gastric bypass (GBP) and sleeve gastrectomy (SG) are both effective bariatric treatments that cause sustained weight loss as well as improvement of type 2 diabetes mellitus (T2DM). The underlying mechanisms are under investigation, including the contribution of alterations in bile acids (BAs) in achieving or maintaining the beneficial metabolic effects after bariatric surgery.

AIMS

The aim of this study is to investigate the acute and short-term effects of GBP and SG on BA compositions and fibroblast growth factor 19 (FGF19) in obese individuals with T2DM and to evaluate any correlations between changes in these measures with glucose metabolic improvements.

METHODS

The levels of both fasting and postprandial plasma BA compositions after oral glucose tolerance test (OGTT), fasting FGF19 and various metabolic indices were measured 1 day before and at 3 days and 3 months after GBP and SG in 19 obese patients (GBP = 8, SG = 11) with T2DM.

RESULTS

Body weight loss was observed after both GBP and SG 3 months post-operatively, with no significant difference between the two intervention groups (15.0 ± 3.1% vs. 13.9 ± 5.2%, P = 0.761). At 3 days post-operation, FGF19 levels increased significantly in both surgery groups (GBP, 118.3 ± 57.3 vs. 363.6 ± 131.0 pg mL^-1, post-operation P = 0.008; SG, 173.2 ± 127.8 vs. 422.0 ± 243.6 pg mL^-1, post-operation P = 0.001). Fasting and postprandial increases from pre-operative values in secondary (r = 0.57, P = 0.02; r = 0.58, P = 0.01), conjugated (r = 0.50, P = 0.01; r = 0.48, P = 0.04), glycine-conjugated (r = 0.52, P = 0.05; r = 0.46, P = 0.05) and secondary-conjugated (r = 0.53, P = 0.02; r = 0.60, P = 0.01) BAs correlated with decreases in the postprandial states of glucose (defined by area under the curve (AUC) over 120 min (AUC_0-120min)). Increases in postprandial primary-conjugated BAs were found to be associated with decreases in HOMA-IR (r = 0.45, P = 0.05). However, increases in fasting and postprandial taurine-conjugated BA correlated with decreases in both basal insulin secretion rate (r = 0.47, P = 0.04; r = 0.48, P = 0.04) and C-peptide level (r = 0.45, P = 0.05; r = 0.47, P = 0.04). After 3 months, fasting and postprandial increases in secondary (r = 0.51, P = 0.03; r = 0.48, P = 0.04), secondary-conjugated (r = 0.52, P = 0.02; r = 0.51, P = 0.03) and non-12α-OH (r = 0.51, P = 0.02; r = 0.58, P = 0.01) BAs were found to correlate with increases in Stumvoll Insulin Sensitivity Index. Increases in both fasting and postprandial 12α-OH BAs were correlated with the decreases in glucose AUC (r = 0.46, P = 0.05; r = 0.41, P = 0.04).

CONCLUSIONS

Both GBP and SG achieve increases in many BA species as early as 3 days post-operation, which are sustained at 3 months post-operation. Rises in secondary BA and conjugated forms are correlated with early improvements in glucose metabolism at 3 days post-operation. These along with 12α-OH BA correlated with improved glucose metabolism at 3 months post-operation, suggesting they may contribute to the observed T2DM remission after bariatric surgery.

New Avenues in the Regulation of Gallbladder Motility-Implications for the Use of Glucagon-Like Peptide-Derived Drugs

CONTEXT

Several cases of cholelithiasis and cholecystitis have been reported in patients treated with glucagon-like peptide 1 (GLP-1) receptor agonists (GLP-1RAs) and GLP-2 receptor agonists (GLP-2RAs), respectively. Thus, the effects of GLP-1 and GLP-2 on gallbladder motility have been investigated. We have provided an overview of the mechanisms regulating gallbladder motility and highlight novel findings on the effects of bile acids and glucagon-like peptides on gallbladder motility.

EVIDENCE ACQUISITION

The articles included in the present review were identified using electronic literature searches. The search results were narrowed to data reporting the effects of bile acids and GLPs on gallbladder motility.

EVIDENCE SYNTHESIS

Bile acids negate the effect of postprandial cholecystokinin-mediated gallbladder contraction. Two bile acid receptors seem to be involved in this feedback mechanism, the transmembrane Takeda G protein-coupled receptor 5 (TGR5) and the nuclear farnesoid X receptor. Furthermore, activation of TGR5 in enteroendocrine L cells leads to release of GLP-1 and, possibly, GLP-2. Recent findings have pointed to the existence of a bile acid-TGR5-L cell-GLP-2 axis that serves to terminate meal-induced gallbladder contraction and thereby initiate gallbladder refilling. GLP-2 might play a dominant role in this axis by directly relaxing the gallbladder. Moreover, recent findings have suggested GLP-1RA treatment prolongs the refilling phase of the gallbladder.

CONCLUSIONS

GLP-2 receptor activation in rodents acutely increases the volume of the gallbladder, which might explain the risk of gallbladder diseases associated with GLP-2RA treatment observed in humans. GLP-1RA-induced prolongation of human gallbladder refilling may explain the gallbladder events observed in GLP-1RA clinical trials.

Lipid profile change after bariatric surgeries: laparoscopic gastric plication versus mini gastric bypass

INTRODUCTION

Bariatric surgeries are known to have profound effects on lipid profile. Laparoscopic gastric plication (LGP) has been shown to have a comparable effect on weight loss rather than Roux-en-Y gastric bypass (RYGB) and mini gastric bypass (MGB). But the post-operative effect on lipid profile is not well-compared. We aimed to compare post-operative lipid profile change after LGP and MGB.

METHODS

In a retrospective analysis, we reviewed 91 patients for at least 12 months. Patients were assigned to undergo either LGP (71 patients) or MGB (20 patients). Preoperative and postoperative visits were accomplished and weight, BMI, fasting blood glucose (FBG) and lipid profile including triglyceride (TG), and total cholesterol (TC) levels were repeatedly measured. Follow up rate for the first year was 100%.

RESULTS

LGP significantly decreased both TG and TC levels in each follow up (all p values < .05). The same trends were observed in BMI reduction, total body weight loss percentage, and FBG. When comparing either TC or TG level between LGP and MGB, there was just one statistically significant result in TG reduction at 6 months (p value = .042) while MGB showed more reduction. All other variables in different follow up visits were not significantly different between two techniques.

CONCLUSIONS

LGP would result in lipid profile improvement lasting at least for one year. Lipid-lowering effect seems to be similar between LGP and MGB. This lipid-lowering property and weight reduction might be indicative that LGP is an alternative for RYGB and MGB in selective patients.

Changes in Bile Acid Metabolism, Transport, and Signaling as Central Drivers for Metabolic Improvements After Bariatric Surgery

PURPOSE OF REVIEW

We review current evidence regarding changes in bile acid (BA) metabolism, transport, and signaling after bariatric surgery and how these might bolster fat mass loss and energy expenditure to promote improvements in type 2 diabetes (T2D) and nonalcoholic fatty liver disease (NAFLD).

RECENT FINDINGS

The two most common bariatric techniques, Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG), increase the size and alter the composition of the circulating BA pool that may then impact energy metabolism through altered activities of BA targets in the many tissues perfused by systemic blood. Recent reports in human patients indicate that gene expression of the major BA target, the farnesoid X receptor (FXR), is increased in the liver but decreased in the small intestine after RYGB. In contrast, intestinal expression of the transmembrane G protein-coupled BA receptor (TGR5) is upregulated after surgery. Despite these apparent conflicting changes in receptor transcription, changes in BAs after both RYGB and VSG are associated with elevated postprandial systemic levels of fibroblast growth factor 19 (from FXR activation) and glucagon-like peptide 1 (from TGR5 activation). These signaling activities are presumed to support fat mass loss and related metabolic benefits of bariatric surgery, and this supposition is in agreement with findings from rodent models of RYGB and VSG. However, inter-species differences in BA physiology limit direct translation and mechanistic understanding of how changes in individual BA species contribute to post-operative improvements of T2D and NAFLD in humans. Thus, details of all these changes and their influences on BAs' biological actions are still under scrutiny. Changes in BA physiology and receptor activities after RYGB and VSG likely support weight loss and promote sustained metabolic improvements.

Reversing Type 2 Diabetes: A Narrative Review of the Evidence

BACKGROUND

Type 2 diabetes (T2D) has long been identified as an incurable chronic disease based on traditional means of treatment. Research now exists that suggests reversal is possible through other means that have only recently been embraced in the guidelines. This narrative review examines the evidence for T2D reversal using each of the three methods, including advantages and limitations for each.

METHODS

A literature search was performed, and a total of 99 original articles containing information pertaining to diabetes reversal or remission were included.

RESULTS

Evidence exists that T2D reversal is achievable using bariatric surgery, low-calorie diets (LCD), or carbohydrate restriction (LC). Bariatric surgery has been recommended for the treatment of T2D since 2016 by an international diabetes consensus group. Both the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) now recommend a LC eating pattern and support the short-term use of LCD for weight loss. However, only T2D treatment, not reversal, is discussed in their guidelines.

CONCLUSION

Given the state of evidence for T2D reversal, healthcare providers need to be educated on reversal options so they can actively engage in counseling patients who may desire this approach to their disease.

Long-term diabetes outcomes after bariatric surgery-managing medication withdrawl

BACKGROUND/OBJECTIVES

Bariatric surgery leads to type 2 diabetes mellitus (T2DM) remission, but recurrence can ensue afterwards. However, literature provides heterogenous remission/recurrence criteria and there is no consensus on long-term T2DM management after surgery. We aim to assess T2DM remission/recurrence rates using standardized criteria and to identify relapse predictors. We also intend to analyze the management of residual T2DM and the impact of maintaining/withdrawing metformin in avoiding future relapse.

SUBJECTS/METHODS

We investigated a cohort of 110 obese patients with T2DM who underwent bariatric surgery and were followed for 5 years (Y0-Y5). Patients who ever attained remission were accounted for cumulate remission, while prevalent remission was considered for individuals who were on remission in a specific visit.

RESULTS

A complete prevalent remission of 47.3% was reached at Y1 and it remained stable till Y5 (46.4-48.2%). Complete cumulative rate was of 57.3% at Y5. Five-year T2DM recurrence rate was 15.9% and it was associated with higher pre-operative HbA1c levels (β = 1.06; p < 0.05) and a milder excess body weight loss (EBWL) (β = 0.49; p < 0.05). Glucose-lowering agents were fully stopped in 51.4% of the patients till Y1 and in 16.2% of them afterwards. Medication withdrawal was mainly attempted in patients with a lower baseline HbA1c (β = 0.54; p < 0.01) and higher first-year EBWL (β = 1.04; p < 0.01). Patients that kept metformin after reaching a HbA1c in the complete remission range (<6.0%) did not have greater odds of avoiding relapse in the next visit (OR = 0.33; p = 0.08).

CONCLUSIONS

Baseline HbA1c and EBWL were the main variables driving both T2DM relapse after bariatric surgery and the attempt to withdrawal anti-diabetic medication. In our population keeping metformin once an HbA1c < 6.0% is achieved did not seem to diminish relapse but further studies on this matter are needed.

Concomitant PPARα and FXR Activation as a Putative Mechanism of NASH Improvement after Gastric Bypass Surgery: a GEO Datasets Analysis

BACKGROUND

Compared to non-surgical weight loss (Diet), weight loss after Roux-en-Y gastric bypass (RYGB) results in greater rates of non-alcoholic steatohepatitis (NASH) resolution. Changes in bile acid physiology and farnesoid X receptor (FXR) signaling are suspected mediators of postoperative NASH improvement. Recent experimental evidence suggests that upregulation of hepatic peroxisome proliferator-activated receptor α (PPARα) activity might also impact NASH improvement. As FXR partly regulates PPARα, we compared resolution of NASH and changes in hepatic PPARα and FXR gene expression following Diet and RYGB.

METHODS

We searched the Gene Expression Omnibus database to identify human studies with liver biopsies containing genomic data and histologic NASH features, at baseline and after Diet or RYGB. Microarray data were extracted for PPARα and FXR gene expression analyses using GEOquery R package v.2.42.0.

RESULTS

We identified one study (GSE83452) where patients underwent either Diet (n = 29) or RYGB (n = 25). NASH prevalence was similar at baseline (Diet 76% versus RYGB 60%, P = ns). After 1 year, NASH resolved in 93.3% of RYGB but only in 27.3% of Diet (P < 0.001). Hepatic PPARα and FXR gene expression increased only after RYGB (P < 0.001). These changes were also found when analyzing only patients that resolved NASH (P < 0.01), and patients without NASH at baseline and follow-up (P < 0.05).

CONCLUSIONS

Compared to Diet, RYGB results in greater NASH resolution with concurrent upregulation of hepatic PPARα and FXR. Our findings point to concurrent PPARα and FXR activation, triggered by RYGB, as a potential mechanism to improve NASH.

A Meta-Analysis of GLP-1 After Roux-En-Y Gastric Bypass: Impact of Surgical Technique and Measurement Strategy

BACKGROUND

Roux-en-Y gastric bypass (RYGB) is an effective treatment for diabetes. Glucagon-like peptide-1 (GLP-1) is a gut hormone that is important to glucose homeostasis.

OBJECTIVE

This study aimed to assess GLP-1 level and its predictors after RYGB.

METHODS

The study design was a meta-analysis. The data sources were MEDLINE, EMBASE, Web of Science, and the Cochrane Databases. The study selection composed of studies with pre- and post-RYGB levels. The main outcomes were as follows: Primary outcome was the change in postprandial GLP-1 levels after RYGB. Secondary outcomes included the changes in fasting glucose, fasting insulin, and fasting GLP-1 levels after RYGB. Meta-regression to determine predictors of changes in GLP-1 levels was performed. Outcomes were reported using Hedge's g.

RESULTS

Twenty-four studies with 368 patients were included. Postprandial GLP-1 levels increased after RYGB (Hedge's g = 1.29, p < 0.0001), while fasting GLP-1 did not change (p = 0.23). Peak postprandial GLP-1 levels gave the most consistent results (I ² = 9.11). Fasting glucose and insulin levels decreased after RYGB (p < 0.0001). Roux limb length was a significant predictor for amount of GLP-1 increase (β = - 0.01, p = 0.02). Diabetes status, amount of weight loss, length of biliopancreatic limb, and time of measurement were not significant predictors (p > 0.05).

CONCLUSION

Postprandial GLP-1 levels increase after RYGB, while fasting levels remain unchanged. Shorter Roux limb length is associated with greater increase in postprandial GLP-1, which may lead to better glycemic control in this population.

Pharmacological Applications of Bile Acids and Their Derivatives in the Treatment of Metabolic Syndrome

Apart from well-known functions of bile acids in digestion and solubilization of lipophilic nutrients and drugs in the small intestine, the emerging evidence from the past two decades identified the role of bile acids as signaling, endocrine molecules that regulate the glucose, lipid, and energy metabolism through complex and intertwined pathways that are largely mediated by activation of nuclear receptor farnesoid X receptor (FXR) and cell surface G protein-coupled receptor 1, TGR5 (also known as GPBAR1). Interactions of bile acids with the gut microbiota that result in the altered composition of circulating and intestinal bile acids pool, gut microbiota composition and modified signaling pathways, are further extending the complexity of biological functions of these steroid derivatives. Thus, bile acids signaling pathways have become attractive targets for the treatment of various metabolic diseases and metabolic syndrome opening the new potential avenue in their treatment. In addition, there is a significant effort to unveil some specific properties of bile acids relevant to their intrinsic potency and selectivity for particular receptors and to design novel modulators of these receptors with improved pharmacokinetic and pharmacodynamic profiles. This resulted in synthesis of few semi-synthetic bile acids derivatives such as 6α-ethyl-chenodeoxycholic acid (obeticholic acid, OCA), norursodeoxycholic acid (norUDCA), and 12-monoketocholic acid (12-MKC) that are proven to have positive effect in metabolic and hepato-biliary disorders. This review presents an overview of the current knowledge related to bile acids implications in glucose, lipid and energy metabolism, as well as a potential application of bile acids in metabolic syndrome treatment with future perspectives.