Increased Bile Acids and FGF19 After Sleeve Gastrectomy and Roux-en-Y Gastric Bypass Correlate with Improvement in Type 2 Diabetes in a Randomized Trial

Comparative effectiveness of metabolic and bariatric surgeries: a network meta-analysis

Bariatric surgery is recommended for patients with unhealthy weight. Our study aim to compare and rank different bariatric surgical approaches in reducing weight parameters. We searched MEDLINE, Cochrane CENTRAL, Scopus, and Web of Science databases from inception to September 2023. We extracted all outcomes as mean change from the baseline. The mean difference and 95% confidence interval were used as a summary measure. All analysis was conducted with R version 4.2.2 (2022-10-31) and R Studio version 2022.07.2 (2009-2022) (RStudio, Inc.). Included surgeries were: Biliopancreatic diversion (BPD-RYGB), Roux-en-Y Gastric Bypass (RYGB), Laparoscopic Gastric Plication (LGP), Duodenal-Jejunal Bypass Sleeve (DJBS), Single-anastomosis gastric bypass (SAGB), Laparoscopic vertical banded gastroplasty (LVBG), Sleeve Gastrectomy (SG), Laparoscopic adjustable gastric banding (LAGB), Gastric plication, Biliopancreatic diversion (BPD), and Intra-gastric balloon (IGB). Only clinical trials were included, with outcomes focused on weight parameters such as reductions in BMI (kg/m²), weight (kg), waist circumference (cm), fat mass (kg), and excess weight loss (EWL) (%). Our analysis of 67 studies showed that SADI-S was the best surgical technique in decreasing BMI (kg/m2) (MD = -18.06; 95% CI [-25.31; -10.81]) and DS follows in efficacy with a P-score (MD = -18.88; 95% CI [-31.15; -6.62]) however the pooled analysis was heterogeneous (I2 = 98.5%). For weight (kg), waist circumference (cm), and fat mass (kg), BPD-RYGB was the best surgical technique to reduce these parameters (MD = -41.48; 95% CI [-47.80, -35.51], MD = -29.08; 95% CI [-37.16, -21.00], and MD = -31.11; 95% CI [-38.77, -23.46]; respectively). The pooled analysis was heterogeneous except in fat mass (I2 = 0%, p-value = 0.8). Our network meta-analysis showed that the best surgical technique in increasing EWL (%) was RY-DS (MD = -61.27; % CI [-91.72; -30.82]) the next one in efficacy according to P-score was LVBG (MD = -59.03; % CI [-84.47; -33.59]). SADI-S is most effective in reducing BMI followed by RYGB. DS was associated with most estimated weight loss %.

Impact of Sleeve Gastrectomy on Body Weight and Food Intake Regulation in Diet-Induced Obese Mice

The epidemic of obesity has increased worldwide and is associated with comorbidities such as diabetes and cardiovascular disease. In this context, strategies that modulate body weight and improve glycemic metabolism have increased, and bariatric surgeries such as Sleeve Gastrectomy (SG) have been highlighted in obesity treatment. However, the mechanism by which SG reduces body weight and improves glycemic control remains unknown. Thus, in this study, we aimed to evaluate food intake and the expression of hypothalamic genes involved with the regulation of this process in diet-induced obese mice submitted to SG. For this, we used C57BL/6 mice submitted to a 10-week high-fat diet protocol and submitted to SG. Food intake, fed and fasted glycemia, as well as hypothalamic anorexigenic and orexigenic gene expression were evaluated 4 weeks after the surgical procedure. First, we observed that SG reduces body weight (44.19 ± 0.47 HFD, 43.51 ± 0.71 HFD-SHAM, and 38.22 ± 1.31 HFD-SG), fasting glycemia (115.0 ± 4.60 HFD, 122.4 ± 3.48 HFD-SHAM, and 93.43 ± 4.67 HFD-SG), insulinemia (1.77 ± 0.15 HFD, 1.92 ± 0.27 HFD-SHAM, and 0.93 ± 0.05 HFD-SG), and leptinemia (5.86 ± 1.38 HFD, 6.44 ± 1.51 HFD-SHAM, and 1.43 ± 0.35 HFD-SG) in obese mice. Additionally, SG reduces food (5.15 ± 0.18 HFD, 5.49 ± 0.32, HFD-SHAM, and 3.28 ± 0.26 HFD-SG) and total (16.88 ± 0.88 HFD, 17.05 ± 0.42, HFD-SHAM, and 14.30 ± 0.73 HFD-SG) calorie intake without alterations in anorexigenic and orexigenic gene expression. In conclusion, these data indicate that SG improves obesity-associated alterations at least in part by a reduction in food intake. This effect is not associated with the canonical food intake pathway in the hypothalamus, indicating the involvement of non-canonical pathways in this process.

Metabolic/Bariatric Surgery is Safe and Effective in People with Obesity, Type 2 Diabetes Mellitus and Chronic Kidney Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Obesity, type 2 diabetes (T2D), and chronic kidney disease (CKD) are thought to increase surgical risks and reduce weight loss after metabolic/bariatric surgery (MBS). Electronic databases were searched between January 2013 and August 2023 for randomized controlled trials (RCT) of MBS reporting data on the safety, total weight loss (TWL), and metabolic control in patients with and without CKD. Forty-four out of 2904 articles were analyzed, representing 1470 patients. No significant differences were found in TWL after 1 year (- 19%, CI - 0.19 to - 0.18 vs.: - 15%, CI - 0.20 to - 0.09, p = 0.13) or after 5 years (- 20%, CI - 0.21 to - 0.18 vs. Group - 16%, CI - 0.28 to - 0.04, p = 0.50).Similarly, there were no significant differences in HbA1c at 1 year (- 1.06, CI - 1.37 to - 0.76 vs. Group 2: - 1.52, CI - 2.25 to - 0.79, p = 0.26) or after 5 years (- 0.97, CI - 1.53 to 0.41 vs. Group 2: - 1.09, CI - 2.21 to 0.03, p = 0.85). For fasting plasma glucose, no differences were seen at 2 years (- 30.43, CI - 60.47 to 0.39 vs. - 35.11, CI - 48.76 to - 21.46, p = 0.78) or after 5 years (- 11.24, CI - 53.38 to 30.89 vs. - 5.4, CI 20.22 to 9.42, p = 0.80). In terms of total cholesterol, no significant differences were found after 1 year (- 10.36, CI - 32.94 to 12.22 vs. - 19.80, CI - 39.46 to - 0.14, p = 0.54) or after 5 years (- 7.43, CI - 25.09 to 5.23 vs. - 21.30, CI - 43.08 to 0.49, p = 0.15). For triglycerides, both showed similar reductions after 1 year (- 76.21, CI - 112.84 to - 39.59 vs. - 78.00, CI - 100.47 to - 55.53, p = 0.94) and after 5 years (- 79.65, CI - 121.09 to - 38.21 vs. - 53.15, CI - 71.14 to - 35.16, p = 0.25). The presence of CKD in patients with obesity and T2D does not reduce the safety and efficacy of MBS.

Bile Acid Signaling in Metabolic and Inflammatory Diseases and Drug Development

Bile acids are the end products of cholesterol catabolism. Hepatic bile acid synthesis accounts for a major fraction of daily cholesterol turnover in humans. Biliary secretion of bile acids generates bile flow and facilitates biliary secretion of lipids, endogenous metabolites, and xenobiotics. In intestine, bile acids facilitate the digestion and absorption of dietary lipids and fat-soluble vitamins. Through activation of nuclear receptors and G protein-coupled receptors and interaction with gut microbiome, bile acids critically regulate host metabolism and innate and adaptive immunity and are involved in the pathogenesis of cholestasis, metabolic dysfunction-associated steatotic liver disease, alcohol-associated liver disease, type-2 diabetes, and inflammatory bowel diseases. Bile acids and their derivatives have been developed as potential therapeutic agents for treating chronic metabolic and inflammatory liver diseases and gastrointestinal disorders. SIGNIFICANCE STATEMENT: Bile acids facilitate biliary cholesterol solubilization and dietary lipid absorption, regulate host metabolism and immunity, and modulate gut microbiome. Targeting bile acid metabolism and signaling holds promise for treating metabolic and inflammatory diseases.

Cholelithiasis, Gut Microbiota and Bile Acids after Bariatric Surgery-Can Cholelithiasis Be Prevented by Modulating the Microbiota? A Literature Review

BACKGROUND

Cholelithiasis is one of the more common complications following bariatric surgery. This may be related to the rapid weight loss during this period, although the exact mechanism of gallstone formation after bariatric surgery has not been fully elucidated.

METHODS

The present literature review focuses on risk factors, prevention options and the impact of the gut microbiota on the development of gallbladder stones after bariatric surgery.

RESULTS

A potential risk factor for the development of cholelithiasis after bariatric surgery may be changes in the composition of the intestinal microbiota and bile acids. One of the bile acids-ursodeoxycholic acid-is considered to reduce the concentration of mucin proteins and thus contribute to reducing the formation of cholesterol crystals in patients with cholelithiasis. Additionally, it reduces the risk of both asymptomatic and symptomatic gallstones after bariatric surgery. Patients who developed gallstones after bariatric surgery had a higher abundance of Ruminococcus gnavus and those who did not develop cholelithiasis had a higher abundance of Lactobacillaceae and Enterobacteriaceae.

CONCLUSION

The exact mechanism of gallstone formation after bariatric surgery has not yet been clarified. Research suggests that the intestinal microbiota and bile acids may have an important role in this.

Vertical Sleeve Gastrectomy Reduces Gut Luminal Deoxycholic Acid Concentrations in Mice

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

CYP8B1 downregulation mediates the metabolic effects of vertical sleeve gastrectomy in mice

BACKGROUND AND AIMS

Although the benefits of vertical sleeve gastrectomy (VSG) surgery are well known, the molecular mechanisms by which VSG alleviates obesity and its complications remain unclear. We aim to determine the role of CYP8B1 (cytochrome P450, family 8, subfamily B, polypeptide 1) in mediating the metabolic benefits of VSG.

APPROACH AND RESULTS

We found that expression of CYP8B1, a key enzyme in controlling the 12α-hydroxylated (12α-OH) bile acid (BA) to non-12α-OH BA ratio, was strongly downregulated after VSG. Using genetic mouse models of CYP8B1 overexpression, knockdown, and knockout, we demonstrated that overexpression of CYP8B1 dampened the metabolic improvements associated with VSG. In contrast, short hairpin RNA-mediated CYP8B1 knockdown improved metabolism similar to those observed after VSG. Cyp8b1 deficiency diminished the metabolic effects of VSG. Further, VSG-induced alterations to the 12α-OH/non-12α-OH BA ratio in the BA pool depended on CYP8B1 expression level. Consequently, intestinal lipid absorption was restricted, and the gut microbiota (GM) profile was altered. Fecal microbiota transplantation from wild type-VSG mice (vs. fecal microbiota transplantation from wild-type-sham mice) improved metabolism in recipient mice, while there were no differences between mice that received fecal microbiota transplantation from knockout-sham and knockout-VSG mice.

CONCLUSIONS

CYP8B1 is a critical downstream target of VSG. Modulation of BA composition and gut microbiota profile by targeting CYP8B1 may provide novel insight into the development of therapies that noninvasively mimic bariatric surgery to treat obesity and its complications.

Safety and Efficacy of LSG Versus LRYGB on Patients with Obesity: a Systematic Review and Meta-analysis from RCTs

BACKGROUND

Laparoscopic Roux-en-Y gastric bypass (LRYGB) and laparoscopic sleeve gastrectomy (LSG) are the two most frequently performed techniques in treating obesity and its related comorbidities. We aimed to compare the clinical efficacy and safety of LSG with LRYGB in terms of short- and mid-term outcomes of weight loss, obesity-related comorbidities, and post-operative complications via a meta-analysis of RCTs.

METHODS

Clinical comparative RCTs on LSG and LRYGB were searched through PubMed, MEDLINE, and Web of Science databases from inception to August 2022. Pooled outcomes from the selected studies were discussed by the random-effect meta-analysis method. Quality assessment and risk of bias for selected RCTs were implemented, and all the statistical analyses were performed.

RESULTS

Twenty studies, including 1270 patients, were enrolled. Meta-analysis results indicated the great superior efficacy of LRYGB to LSG in BMI loss at 6 (MD -1.35 kg/m2, 95% CI: -2.07 to -0.62, p = 0.0003), 12 months (MD -1.09 kg/m2, 95% CI: -1.86 to -0.33, p = 0.005), and 36 months (MD -1.47 kg/m2, 95% CI: -2.77 to -0.16, p = 0.03) as well as %EWL gaining at 36 months. Significantly higher remission rates of T2DM and dyslipidemia were achieved by LRYGB at 12 months. Besides, better improvements for T2DM-related and lipid biochemical parameters were found favoring LRYGB. However, LSG resulted in a lower post-operative complication rate and shorter operating time.

CONCLUSIONS

Present meta-analysis results suggested that LRYGB was superior to LSG concerning short- and mid-term weight loss, short-term T2DM remission efficacy, and related biochemical parameters. LSG is favored for obviously fewer complications and shorter operating time.

Vertical sleeve gastrectomy improves glucose-insulin homeostasis by enhancing β-cell function and survival via FGF15/19

Vertical sleeve gastrectomy (VSG) restores glucose homeostasis in obese mice and humans. In addition, the increased fibroblast growth factor (FGF)15/19 circulating level postsurgery has been implicated in this effect. However, the impact of FGF15/19 on pancreatic islets remains unclear. Using a diet-induced obese mice model, we demonstrate that VSG attenuates insulin hypersecretion in isolated pancreatic islets, likely due to morphological alterations in the endocrine pancreas such as reduction in islet, β-cell, and α-cell mass. In addition, VSG relieves gene expression of endoplasmic reticulum (ER) stress and inflammation markers in islets from obese mice. Incubation of INS-1E β-cells with serum from obese mice induced dysfunction and cell death, whereas these conditions were not induced with serum from obese mice submitted to VSG, implicating the involvement of a humoral factor. Indeed, VSG increased FGF15 circulating levels in obese mice, as well as the expression of FGF receptor 1 (Fgfr1) and its coreceptor β-klotho (Klb), both in pancreatic islets from VSG mice and in INS-1E cells treated with the serum from these mice. Moreover, exposing INS-1E cells to an FGFR inhibitor abolished the effects of VSG serum on insulin secretion and cell death. Also, recombinant FGF19 prevents INS-1E cells from dysfunction and death induced by serum from obese mice. These findings indicate that the amelioration of glucose-insulin homeostasis promoted by VSG is mediated, at least in part, by FGF15/19. Therefore, approaches promoting FGF15/19 release or action may restore pancreatic islet function in obesity.NEW & NOTEWORTHY Vertical sleeve gastrectomy (VSG) decreases insulin secretion, endoplasmic reticulum (ER) stress, and inflammation in pancreatic islets from obese mice. In addition, VSG increased fibroblast growth factor (FGF)15 circulating levels in obese mice, as well as the expression of FGF receptor 1 (Fgfr1) and its coreceptor β-klotho (Klb), both in pancreatic islets from VSG mice and in INS-1E β-cells treated with the serum from these mice. Serum from operated mice protects INS-1E cells from dysfunction and apoptosis, which was mediated by FGF15/19.

Comparing Safety and Efficacy Outcomes of Gastric Bypass and Sleeve Gastrectomy in Patients With Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis

Sleeve Gastrectomy (SG) could be done by the removal of a big portion of the stomach, leading to reduced amounts of food taken as a result of the smaller stomach size. In contrast, Roux-en-Y Gastric Bypass (RYGB) can be done by creating a small stomach pouch and rerouting a part of the small intestine, employing combined mechanisms of restriction and malabsorption to limit food intake and modify nutrient absorption. Our aim is to identify the most effective and safest surgical intervention for individuals with both Type 2 Diabetes Mellitus (T2DM) and obesity, considering both short and long-term outcomes. We will assess participants undergoing either SG or RYGB to determine the optimal surgical approach. We made a thorough search of PubMed, Cochrane Library, Scopus, and Web of Science databases up to November 2023. Our focus was on randomized controlled trials (RCTs) comparing the safety and efficacy of RYGB and SG in T2DM regarding any extractable data. We excluded studies of other designs, such as cohorts, case reports, case series, reviews, in vitro studies, postmortem analyses, and conference abstracts. Utilizing Review Manager 5.4, we performed a meta-analysis, combining risk ratios (RR) with a 95% confidence interval (CI) conducted for binary outcomes, while mean with SD and 95% CI are pooled for the continuous ones. The total number of participants in our study is 4,148 patients. Our analysis indicates superior outcomes in the group undergoing RYGB surgery compared to the SG group (RR = 0.76, 95% (CI) (0.66 to 0.88), P = 0.0002). The pooled data exhibited homogeneity (P = 0.51, I2 = 0%) after employing the leave-one-out method. For the 1-3 year period, six studies involving 332 patients with T2DM yielded non-significant results (RR = 0.83, 95% CI (0.66 to 1.06), P = 0.14) with homogeneity (P = 0.24, I2 = 28%). Conversely, the 5-10 year period, with six studies comprising 728 DM patients, demonstrated significant results (RR = 0.69, 95% CI (0.56 to 0.85), P = 0.14) and homogeneity (P = 0.84, I2 = 0%). In terms of total body weight loss, our findings indicate significantly higher weight loss with RYGB (mean difference (MD) = -6.13, 95% CI (-8.65 to -3.6), P > 0.00001). However, pooled data exhibited considerable heterogeneity (P > 0.00001, I2 = 93%). Subgroup analyses for the 1-3 year period (five studies, 364 DM patients) and 5-10 year period (six studies, 985 DM patients) also revealed significant differences favoring RYGB, with heterogeneity observed in both periods (1-3 years: P > 0.00001, I2 = 95%; 5-10 years: P = 0.001, I2 = 75%). RYGB demonstrated significant long-term improvement in diabetes remission and superior total body weight loss compared to SG. While no notable differences were observed in other efficacy outcomes, safety parameters require further investigation. no significant distinctions were found in any of the safety outcomes: hypertension (HTN), high-density lipoprotein (HDL), hyperlipidemia, fasting blood glucose, vomiting, low-density lipoprotein (LDL), and total cholesterol. Further research is essential to comprehensively assess safety outcomes for both surgical approaches.

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

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

State of art on the mechanisms of laparoscopic sleeve gastrectomy in treating type 2 diabetes mellitus

Obesity and type-2 diabetes mellitus (T2DM) are metabolic disorders. Obesity increases the risk of T2DM, and as obesity is becoming increasingly common, more individuals suffer from T2DM, which poses a considerable burden on health systems. Traditionally, pharmaceutical therapy together with lifestyle changes is used to treat obesity and T2DM to decrease the incidence of comorbidities and all-cause mortality and to increase life expectancy. Bariatric surgery is increasingly replacing other forms of treatment of morbid obesity, especially in patients with refractory obesity, owing to its many benefits including good long-term outcomes and almost no weight regain. The bariatric surgery options have markedly changed recently, and laparoscopic sleeve gastrectomy (LSG) is gradually gaining popularity. LSG has become an effective and safe treatment for type-2 diabetes and morbid obesity, with a high cost-benefit ratio. Here, we review the me-chanism associated with LSG treatment of T2DM, and we discuss clinical studies and animal experiments with regard to gastrointestinal hormones, gut microbiota, bile acids, and adipokines to clarify current treatment modalities for patients with obesity and T2DM.

Effect of sleeve gastrectomy and Roux-en-Y gastric bypass on gastrointestinal physiology

BACKGROUND

Knowledge regarding the gastrointestinal physiology after sleeve gastrectomy and Roux-en-Y gastric bypass is urgently needed to understand, prevent and treat the nutritional and pharmacological complications of bariatric surgery.

AIM

To investigate the effect of sleeve gastrectomy and Roux-en-Y gastric bypass on gastrointestinal motility (e.g., transit and pressure), pH, and intestinal bile acid concentration.

MATERIAL AND METHODS

An exploratory cross-sectional study was performed in six participants living with obesity, six participants who underwent sleeve gastrectomy, and six participants who underwent Roux-en-Y gastric bypass. During the first visit, a wireless motility capsule (SmartPill©) was ingested after an overnight fast to measure gastrointestinal transit, pH, and pressure. During the second visit, a gastric emptying scintigraphy test of a nutritional drink labeled with ^99mTc-colloid by a dual-head SPECT gamma camera was performed to measure gastric emptying half-time (GET_1/2). During the third visit, two customized multiple lumen aspiration catheters were positioned to collect fasting and postprandial intestinal fluids to measure bile acid concentration.

RESULTS

Immediate pouch emptying (P = 0.0007) and a trend for faster GET_1/2 (P = 0.09) were observed in both bariatric groups. There was a tendency for a shorter orocecal transit in participants with sleeve gastrectomy and Roux-en-Y gastric bypass (P = 0.08). The orocecal segment was characterized by a higher 25th percentile pH (P = 0.004) and a trend for a higher median pH in both bariatric groups (P = 0.07). Fasting total bile acid concentration was 7.5-fold higher in the common limb after Roux-en-Y gastric bypass (P < 0.0001) and 3.5-fold higher in the jejunum after sleeve gastrectomy (P = 0.009) compared to obesity. Postprandial bile acid concentration was 3-fold higher in the jejunum after sleeve gastrectomy (P = 0.0004) and 6.5-fold higher in the common limb after Roux-en-Y gastric bypass (P < 0.0001) compared to obesity.

CONCLUSION

The anatomical alterations of sleeve gastrectomy and Roux-en-Y gastric bypass have an important impact on gastrointestinal physiology. This data confirms changes in transit and pH and provides the first evidence for altered intraluminal bile acid concentration.

Sleeve Gastrectomy-Induced Weight Loss Increases Insulin Clearance in Obese Mice

Sleeve gastrectomy (SG) successfully recovers metabolic homeostasis in obese humans and rodents while also resulting in the normalization of insulin sensitivity and insulinemia. Reduced insulin levels have been attributed to lower insulin secretion and increased insulin clearance in individuals submitted to SG. Insulin degradation mainly occurs in the liver in a process controlled, at least in part, by the insulin-degrading enzyme (IDE). However, research has yet to explore whether liver IDE expression or activity is altered after SG surgery. In this study, C57BL/6 mice were fed a chow (CTL) or high-fat diet (HFD) for 10 weeks. Afterward, the HFD mice were randomly assigned to two groups: sham-surgical (HFD-SHAM) and SG-surgical (HFD-SG). Here, we confirmed that SG improves glucose-insulin homeostasis in obese mice. Additionally, SG reduced insulinemia by reducing insulin secretion, assessed by the analysis of plasmatic C-peptide content, and increasing insulin clearance, which was evaluated through the calculation of the plasmatic C-peptide:insulin ratio. Although no changes in hepatic IDE activity were observed, IDE expression was higher in the liver of HFD-SG compared with HFD-SHAM mice. These results indicate that SG may be helpful to counteract obesity-induced hyperinsulinemia by increasing insulin clearance, likely through enhanced liver IDE expression.

Roux-en-Y gastric bypass and laparoscopic sleeve gastrectomy effects on obesity comorbidities: A systematic review and meta-analysis

Roux-en-Y gastric bypass (LRYGB) and laparoscopic sleeve gastrectomy (LSG) are the most commonly used bariatric procedures. There is an increasing awareness about a comorbidity-based indication for bariatric surgery regardless of weight (metabolic surgery). The best operation to mitigate obesity-associated comorbidities is a matter of controversy. This review is aimed at comparing LRYGB and LSG for the treatment of diabetes, hypertension, dyslipidemias, obstructive sleep apnea (OSA), and gastroesophageal reflux (GERD). We searched PubMed, MEDLINE, SCOPUS, Web of Science, and Cochrane library for articles comparing these two commonly used bariatric approaches. We identified 2,457 studies, 1,468 of which stood after the removal of duplications; from them, 81 full texts were screened and only 16 studies were included in the final meta-analysis. LRYGB was equal weight to LSG for diabetes (P-value = 0.10, odd ratio, 1.24, 95% CI, 0.96-1.61, I ² for heterogeneity = 30%, P-value for heterogeneity, 0.14), and OSA (P-value = 0.38, odd ratio, 0.79, 95% CI, 0.47-1.33, I ² for heterogeneity = 0.0%, P-value for heterogeneity, 0.98). However, LRYGB was superior to LSG regarding hypertension (P-value = 0.009, odd ratio, 1.55, 95% CI, 1.20-2.0, I ² for heterogeneity = 0.0%, P-value for heterogeneity, 0.59), dyslipidemia (odd ratio, 2.18, 95% CI, 1.15-4.16, P-value for overall effect, 0.02), and GERD (P-value = 0.003, odd ratio, 3.16, 95% CI, 1.48-6.76). LRYGB was superior to LSG for gastroesophageal reflux, hypertension, and dyslipidemia remission. While the two procedures were equal regarding diabetes and obstructive sleep, further reviews comparing LSG, and one anastomosis gastric bypass are recommended.

Biliopancreatic Limb Length as a Potential Key Factor in Superior Glycemic Outcomes After Roux-en-Y Gastric Bypass in Patients With Type 2 Diabetes: A Meta-Analysis

BACKGROUND

Optimal length of biliopancreatic (BP) and Roux limb in Roux-en-Y gastric bypass (RYGB) for improved glycemic control are not known.

PURPOSE

To investigate how the lengths of the BP and Roux limbs in RYGB differentially affect postoperative glycemic outcomes in patients with type 2 diabetes.

DATA SOURCES

We conducted a systematic literature search using the PubMed, Embase, and the Cochrane Library databases.

STUDY SELECTION

We included studies that reported glycemic outcomes after RYGB and lengths of the BP and Roux limbs.

DATA EXTRACTION

A total of 28 articles were included for data extraction. Glycemic outcomes after RYGB were assessed on the basis of two definitions: remission and improvement.

DATA SYNTHESIS

We categorized the included studies into four groups according to the BP and Roux limb lengths. The type 2 diabetes remission/improvement rates were as follows: long BP-long Roux group 0.80 (95% CI 0.70-0.90)/0.81 (0.73-0.89), long BP-short Roux group 0.76 (0.66-0.87)/0.82 (0.75-0.89), short BP-long Roux group 0.57 (0.36-0.78)/0.64 (0.53-0.75), and short BP-short Roux group 0.62 (0.43-0.80)/0.53 (0.45-0.61). Meta-regression analysis also showed that a longer BP limb resulted in higher postoperative type 2 diabetes remission and improvement rates, whereas a longer Roux limb did not. There was no significant difference or heterogeneity in baseline characteristics, including diabetes-related variables, among the four groups.

LIMITATIONS

Not all included studies were randomized controlled trials.

CONCLUSIONS

Longer BP limb length led to higher rates of type 2 diabetes remission and improvement by 1 year after RYGB in comparisons with the longer Roux limb length.

Effects of Roux-en-Y Gastric Bypass and Sleeve Gastrectomy on β-Cell Function at 1 Year After Surgery: A Systematic Review

Bariatric surgery is a highly effective obesity treatment resulting in substantial weight loss and improved glucose metabolism. We hereby aimed to summarize available evidence of the effect of the 2 most common bariatric surgery procedures, Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG), on dynamic measures of β-cell function (BCF). A systematic search of the literature was conducted in 3 bibliographic databases for studies reporting effects of RYGB and/or SG on BCF assessed using dynamic metabolic perturbation (oral or intravenous bolus stimulation), performed before and 1 year (±3 months) after surgery. Twenty-seven unique studies (6 randomized controlled trials and 21 observational studies), involving a total of 1856 obese adults, were included for final analysis. Twenty-five and 9 studies report effects of RYGB and SG on BCF, respectively (7 studies compared the 2 procedures). Seven studies report results according to presurgical diabetes status. Owing to variable testing procedures and BCF indices reported, no meta-analysis was feasible, and data were summarized qualitatively. For both surgical procedures, most studies suggest an increase in BCF and disposition index, particularly when using oral stimulation, with a more pronounced increase in diabetic than nondiabetic individuals. Additionally, limited indications for greater effects after RYGB versus SG were found. The quality of the included studies was, in general, satisfactory. The considerable heterogeneity of test protocols and outcome measures underscore the need for a harmonization of BCF testing in future research.

An Updated Perspective on the Dual-Track Model of Enterocyte Fat Metabolism

The small intestinal epithelium has classically been envisioned as a conduit for nutrient absorption, but appreciation is growing for a larger and more dynamic role for enterocytes in lipid metabolism. Considerable gaps remain in our knowledge of this physiology, but it appears that the enterocyte's structural polarization dictates its behavior in fat partitioning, treating fat differently based on its absorption across the apical versus the basolateral membrane. In this review, we synthesize existing data and thought on this dual-track model of enterocyte fat metabolism through the lens of human integrative physiology. The apical track includes the canonical pathway of dietary lipid absorption across the apical brush-border membrane, leading to packaging and secretion of those lipids as chylomicrons. However, this track also reserves a portion of dietary lipid within cytoplasmic lipid droplets for later uses, including the "second-meal effect," which remains poorly understood. At the same time, the enterocyte takes up circulating fats across the basolateral membrane by mechanisms that may include receptor-mediated import of triglyceride-rich lipoproteins or their remnants, local hydrolysis and internalization of free fatty acids, or enterocyte de novo lipogenesis using basolaterally absorbed substrates. The ultimate destinations of basolateral-track fat may include fatty acid oxidation, structural lipid synthesis, storage in cytoplasmic lipid droplets, or ultimate resecretion, although the regulation and purposes of this basolateral track remain mysterious. We propose that the enterocyte integrates lipid flux along both of these tracks in order to calibrate its overall program of lipid metabolism.

Effect of Banded Roux-en-Y Gastric Bypass Versus Sleeve Gastrectomy on Diabetes Remission at 5 Years Among Patients With Obesity and Type 2 Diabetes: A Blinded Randomized Clinical Trial

OBJECTIVE

To determine whether silastic ring laparoscopic Roux-en-Y gastric bypass (SR-LRYGB) or laparoscopic sleeve gastrectomy (LSG) produces superior diabetes remission at 5 years.

RESEARCH DESIGN AND METHODS

In a single-center, double-blind trial, 114 adults with type 2 diabetes and BMI 35-65 kg/m2 were randomly assigned to SR-LRYGB or LSG (1:1; stratified by age-group, BMI group, ethnicity, diabetes duration, and insulin therapy) using a web-based service. Diabetes and other metabolic medications were adjusted according to a prespecified protocol. The primary outcome was diabetes remission assessed at 5 years, defined by HbA1c <6% (42 mmol/mol) without glucose-lowering medications. Secondary outcomes included changes in weight, cardiometabolic risk factors, quality of life, and adverse events.

RESULTS

Diabetes remission after SR-LRYGB versus LSG occurred in 25 (47%) of 53 vs. 18 (33%) of 55 patients (adjusted odds ratios 4.5 [95% CI 1.6, 15.5; P = 0.009] and 4.2 [1.3, 13.4; P = 0.015] in the intention-to-treat analysis). Percent body weight loss was greater after SR-LRYGB than after LSG (absolute difference 10.7%; 95% CI 7.3, 14.0; P < 0.001). Improvements in cardiometabolic risk factors were similar, but HDL cholesterol increased more after SR-LRYGB. Early and late complications were similar in both groups. General health and physical functioning improved after both types of surgery, with greater improvement in physical functioning after SR-LRYGB. People of Māori or Pacific ethnicity (26%) had lower incidence of diabetes remission than those of New Zealand European or other ethnicities (2 of 25 vs. 41 of 83; P < 0.001).

CONCLUSIONS

SR-LRYGB provided superior diabetes remission and weight loss compared with LSG at 5 years, with similar low risks of complications.

The Role of Bile Acid in Improving Glucose Tolerance of Non-Obese Diabetic Rats After Proximal Small Bowel Bypass

An increase in bile acid (BA) levels after metabolic surgery is an important mechanism for improving glucose metabolism. However, the mechanisms underlying elevated BA levels and the regulatory mechanism of glucose metabolism remain unclear. In this study, we used the Goto-Kakizaki rat model to investigate the mechanism of BA elevation by comparing side-to-side jejunoileal bypass plus proximal loop ligation (SSJIBL) and bile ileum diversion (BID) as well as to explore the mechanism of BA metabolism in regulating blood glucose. The results showed that the fed blood glucose of rats in both the SSJIBL and BID groups was significantly lower than that of the SHAM group on days 2 and 14 after the operation. The oral glucose tolerance test (OGTT) improved in the SSJIBL and BID groups at day 14 postoperatively. The expression of CYP27A1 in the livers of the SSJIBL and BID groups was significantly increased. In addition, total serum BA levels in the SSJIBL and BID groups were significantly increased. Moreover, serum levels of lithocholic acid (LCA) and deoxycholic acid (DCA) were significantly higher in the SSJIBL group than in the SHAM group and negatively correlated with the area under the glucose tolerance curve (AUC-OGTT). In conclusion, increased BA synthesis may be an important cause of elevated total serum BA levels, and LCA and DCA are closely associated with improved glucose metabolism.

Discovery of farnesoid X receptor and its role in bile acid metabolism

In 1995, the nuclear hormone orphan receptor farnesoid X receptor (FXR, NR1H4) was identified as a farnesol receptor expressed mainly in liver, kidney, and adrenal gland of rats. In 1999, bile acids were identified as endogenous FXR ligands. Subsequently, FXR target genes involved in the regulation of hepatic bile acid synthesis, secretion, and intestinal re-absorption were identified. FXR signaling was proposed as a mechanism of feedback regulation of the rate-limiting enzyme for bile acid synthesis, cholesterol 7⍺-hydroxylase (CYP7A1). The primary bile acids synthesized in the liver are transformed to secondary bile acids by the gut microbiota. The gut-to-liver axis plays a critical role in the regulation of bile acid synthesis, composition and circulating bile acid pool size, which in turn regulates glucose, lipid, and energy metabolism. Dysregulation of bile acid metabolism and FXR signaling in the gut-to-liver axis contributes to metabolic diseases including obesity, diabetes, and non-alcoholic fatty liver disease. This review will cover the discovery of FXR as a bile acid sensor in the regulation of bile acid metabolism and as a metabolic regulator of lipid, glucose, and energy homeostasis. It will also provide an update of FXR functions in the gut-to-liver axis and the drug therapies targeting bile acids and FXR for the treatment of liver metabolic diseases.

Neurohormonal Changes in the Gut–Brain Axis and Underlying Neuroendocrine Mechanisms following Bariatric Surgery

Obesity is a complex, multifactorial disease that is a major public health issue worldwide. Currently approved anti-obesity medications and lifestyle interventions lack the efficacy and durability needed to combat obesity, especially in individuals with more severe forms or coexisting metabolic disorders, such as poorly controlled type 2 diabetes. Bariatric surgery is considered an effective therapeutic modality with sustained weight loss and metabolic benefits. Numerous genetic and environmental factors have been associated with the pathogenesis of obesity, while cumulative evidence has highlighted the gut–brain axis as a complex bidirectional communication axis that plays a crucial role in energy homeostasis. This has led to increased research on the roles of neuroendocrine signaling pathways and various gastrointestinal peptides as key mediators of the beneficial effects following weight-loss surgery. The accumulate evidence suggests that the development of gut-peptide-based agents can mimic the effects of bariatric surgery and thus is a highly promising treatment strategy that could be explored in future research. This article aims to elucidate the potential underlying neuroendocrine mechanisms of the gut–brain axis and comprehensively review the observed changes of gut hormones associated with bariatric surgery. Moreover, the emerging role of post-bariatric gut microbiota modulation is briefly discussed.

Bariatric Surgery in NAFLD

Currently, there are no approved medications to treat patients with nonalcoholic steatohepatitis (NASH) with fibrosis or cirrhosis. Although the management goal in these patients is weight reduction by 7-10% with lifestyle modifications, only less than 10% of patients achieve this target at 1-year, and fewer maintain the weight loss at 5 years. Bariatric surgery is an option that may be considered in those who fail to lose weight by lifestyle changes. Bariatric surgery has been shown to improve liver histology including fibrosis secondary to NASH, in addition to other benefits including an improvement or resolution of type 2 diabetes mellitus, dyslipidemia, and hypertension, and a reduction of cardiovascular morbidity or mortality. There are no guidelines of bariatric surgery indications for the management of NASH. The purpose of this review is to critically appraise the current knowledge of the role of bariatric surgery and the potential mechanisms for its perceived benefits in the management of patients with NASH-related liver disease.

Bile acids, gut microbiota and metabolic surgery

Metabolic surgery, or bariatric surgery, is currently the most effective approach for treating obesity and its complications. Vertical sleeve gastrectomy (VSG) and Roux-en-Y gastric bypass (RYGB) are the top two types of commonly performed metabolic surgery now. The precise mechanisms of how the surgeries work are still unclear, therefore much research has been conducted in this area. Gut hormones such as GLP-1 and PYY have been studied extensively in the context of metabolic surgery because they both participate in satiety and glucose homeostasis. Bile acids, whose functions cover intestinal lipid absorption and various aspects of metabolic regulation via the action of FXR, TGR5, and other bile acid receptors, have also been actively investigated as potential mediators of metabolic surgery. Additionally, gut microbiota and their metabolites have also been studied because they can affect metabolic health. The current review summarizes and compares the recent scientific progress made on identifying the mechanisms of RYGB and VSG. One of the long-term goals of metabolic/bariatric surgery research is to develop new pharmacotherapeutic options for the treatment of obesity and diabetes. Because obesity is a growing health concern worldwide, there is a dire need in developing novel non-invasive treatment options.

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.

Effect of Bariatric Surgery on Metabolic Diseases and Underlying Mechanisms

Obesity is a highly prevalent public health concern, attributed to multifactorial causes and limited in treatment options. Several comorbidities are closely associated with obesity such as the development of type 2 diabetes mellitus (T2DM), cardiovascular and cerebrovascular diseases, and nonalcoholic fatty liver disease (NAFLD). Bariatric surgery, which can be delivered in multiple forms, has been remarked as an effective treatment to decrease the prevalence of obesity and its associated comorbidities. The different types of bariatric surgery create a variety of new pathways for food to metabolize in the body and truncate the stomach's caliber. As a result, only a small quantity of food is tolerated, and the body mass index noticeably decreases. This review describes the improvements of obesity and its comorbidities following bariatric surgery and their mechanism of improvement. Additionally, endocrine function improvements after bariatric surgery, which contributes to the patients' health improvement, are described, including the role of glucagon-like peptide-1 (GLP-1), fibroblast growth factors 19 and 21 (FGF-19, FGF-21), and pancreatic peptide YY (PYY). Lastly, some of the complications of bariatric surgery, including osteoporosis, iron deficiency/anemia, and diarrhea, as well as their potential mechanisms, are described.

Surgical, metabolic, and prognostic outcomes for Roux-en-Y gastric bypass versus sleeve gastrectomy: a systematic review

The purpose of this systematic review was to study 4 different aspects of Roux-en-Y gastric bypass (RYBG) and sleeve gastrectomy (SG). Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) are two commonly performed bariatric procedures. This systematic review aims to compare RYGB with SG when it comes to weight changes, and cardiometabolic risk profile. Another aim was to evaluate laparoscopic and robotic techniques for both surgeries. PubMED, Cochrane Library, and JAMA Network were searched for articles evaluating RYGB and SG from 2005-2020. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were followed. Four different categories were analyzed comparing RYGB with SG as well as robotic versus laparoscopic approach. The Critical Appraisal Skills Program (CASP) checklist was used to assess the quality of evidence in the studies included in this systematic review. A total of 29 studies were included looking at different aspects of RYGB and SG. RYGB is superior to SG for weight loss, improved or complete remission of cholesterol and hypertensive medications. Consensus is lacking regarding decrease in BMI, total cholesterol, and triglycerides. There is lack of evidence regarding decrease of incidence of MI or stroke. For RYGB and SG, the majority of studies found that the robotic technique was more expensive and took longer. RYGB when compared with SG was associated with larger weight loss, decreased or cessation of cholesterol and hypertensive medications, and lower cholesterol. Decrease in BMI had varying results, with RYGB being superior in more studies, while there was no difference in other studies. There was a lack of evidence to support if RYGB or SG was superior to decreasing triglyceride levels. For both RYGB and SG, the robotic approach was costlier and took more operating time versus the laparoscopic approach.

Potential gut-brain mechanisms behind adverse mental health outcomes of bariatric surgery

Bariatric surgery induces sustained weight loss and metabolic benefits via notable effects on the gut-brain axis that lead to alterations in the neuroendocrine regulation of appetite and glycaemia. However, in a subset of patients, bariatric surgery is associated with adverse effects on mental health, including increased risk of suicide or self-harm as well as the emergence of depression and substance use disorders. The contributing factors behind these adverse effects are not well understood. Accumulating evidence indicates that there are important links between gut-derived hormones, microbial and bile acid profiles, and disorders of mood and substance use, which warrant further exploration in the context of changes in gut-brain signalling after bariatric surgery. Understanding the basis of these adverse effects is essential in order to optimize the health and well-being of people undergoing treatment for obesity.

Progress in treatment of type 2 diabetes by bariatric surgery

The incidence of type 2 diabetes (T2D) is increasing at an alarming rate worldwide. Bariatric surgical procedures, such as the vertical sleeve gastrectomy and Roux-en-Y gastric bypass, are the most efficient approaches to obtain substantial and durable remission of T2D. The benefits of bariatric surgery are realized through the consequent increased satiety and alterations in gastrointestinal hormones, bile acids, and the intestinal microbiota. A comprehensive understanding of the mechanisms by which various bariatric surgical procedures exert their benefits on T2D could contribute to the design of better non-surgical treatments for T2D. In this review, we describe the classification and evolution of bariatric surgery and explore the multiple mechanisms underlying the effect of bariatric surgery on insulin resistance. Based upon our summarization of the current knowledge on the underlying mechanisms, we speculate that the gut might act as a new target for improving T2D. Our ultimate goal with this review is to provide a better understanding of T2D pathophysiology in order to support development of T2D treatments that are less invasive and more scalable.

Effect of Sleeve Gastrectomy on Plasma Thioredoxin-Interacting Protein (TXNIP)

PURPOSE

The mechanism in which bariatric surgery induces diabetes remission is still poorly understood. This study proposes Thioredoxin-interacting protein (TXNIP) as a possible factor for the anti-diabetic mechanism after sleeve gastrectomy (SG).

MATERIALS AND METHODS

Plasma TXNIP level in obesity patients with diabetes (T2D, N = 20), obesity patients without diabetes (NDO, N = 20), and patients without obesity and diabetes (lean, N = 10) were assessed before surgery and at 1 and 12 months after SG.

RESULTS

Preoperative TXNIP level was significantly higher in T2D (196.4 ± 76.0 pg/ml) and NDO (149.7 ± 94.1 pg/ml) patients when compared with lean patients (98.7 ± 22.7 pg/ml) (p-value < 0.05). At 1 month and 12 months postoperatively, the TXNIP levels were reduced significantly from the preoperative levels in the T2D and NDO patients (p-value < 0.05). Before surgery, a correlation between TXNIP and fasting blood glucose (FBG) (r² = 0.1585, p-value = 0.0109), HbA1C (r² = 0.2120, p-value = 0.0028), and insulin (r² = 0.1217, p-value = 0.0274) was observed. At 12 months after surgery, the reduction of TXNIP was also correlated with the degree of FBG (r² = 0.1038, p-value = 0.0426), HbA1C (r² = 0.2459, p-value = 0.0011), and insulin (r² = 0.1365, p-value = 0.0190) reduction.

CONCLUSION

Plasma TXNIP level is elevated in obesity patients with/without diabetes. SG resulted in a significant reduction of plasma TXNIP level which is correlated with the degree of FBG, HbA1C, and insulin reduction. Regulation of TXNIP could be part of the mechanism of diabetes remission after bariatric surgery.

Combined ASBT Inhibitor and FGF15 Treatment Improves Therapeutic Efficacy in Experimental Nonalcoholic Steatohepatitis

BACKGROUND & AIMS

Pharmacologic agents targeting bile acid signaling show promise for treating nonalcoholic steatohepatitis (NASH). However, clinical findings suggest that new treatment strategies with enhanced therapeutic efficacy and minimized undesired effects are needed. This preclinical study investigates whether combining an apical sodium-bile acid transporter (ASBT) inhibitor GSK233072 (GSK672) and fibroblast growth factor-15 (FGF15) signaling activation improves anti-NASH efficacy.

METHODS

Mice with high fat, cholesterol, and fructose (HFCFr) diet-induced NASH and stage 2 fibrosis are used as a NASH model. GSK672 or AAV8-TBG-FGF15 interventions are administered alone or in combination to HFCFr diet-fed mice.

RESULTS

The combined treatment significantly enhances therapeutic efficacy against steatosis, inflammation, ballooning, and fibrosis than either single treatment. Mechanistically, the synergistic actions of GSK672 and FGF15 on inhibiting gut bile acid reuptake and hepatic bile acid synthesis achieve greater magnitude of bile acid pool reduction that not only decreases bile acid burden in NASH livers but also limits intestinal lipid absorption, which, together with FGF15 signaling activation, produces weight loss, reduction of adipose inflammation, and attenuated hepatocellular organelle stress. Furthermore, the combined treatment attenuates increased fecal bile acid excretion and repressed bile acid synthesis, which underlie diarrhea and hypercholesterolemia associated with ASBT inhibition and FGF19 analogue, respectively, in clinical settings.

CONCLUSIONS

Concomitant ASBT inhibition and FGF15 signaling activation produce metabolic changes that partially mimic the bariatric surgery condition whereby lipid malabsorption and increased FGF15/19 signaling synergistically mediate weight loss and metabolic improvement. Further clinical studies may be warranted to investigate whether combining ASBT inhibitor and FGF19 analogue enhances anti-NASH efficacy and reduced treatment-associated adverse events in humans.

The effects of bariatric surgery on dyslipidemia and insulin resistance in overweight patients with or without type 2 diabetes: a systematic review and network meta-analysis

Obesity has become an epidemic in several regions globally; it may lead to cardiovascular diseases, diabetes, and dyslipidemia. Despite many therapies, all bariatric procedures fail in some patients. There is a lack of literature comparing treatment effects on specific metabolic indexes. PubMed, Embase, and Cochrane Central Register of Controlled Trials were searched for relevant articles. GeMTC and R software were used to perform a network meta-analysis, draw forest plots, investigate the possibility of statistical heterogeneity, generate I² statistics, rank probabilities, and evaluate relative effects of surgical procedures. All analyses were based on a Bayesian consistency model. We included 35 randomized controlled trials, comprising 2198 individuals and 13 interventions. For patients with high insulin resistance, single-anastomosis (mini-) gastric bypass (SAGB) and sleeve gastrectomy (SG) may be effective options, with mean differences (95% confidence intervals [CIs]) of -4.45 (-9.04 to -.34) and -4.23 (-6.74 to -2.22), respectively, compared with control groups. For patients with severe dyslipidemia, in addition to SAGB and SG, duodenal switch (DS) may be an effective surgery, with mean differences (95% CIs) of -.97 (-1.39 to -.55), -1.98 (-3.76 to -.19), .53 (.04 to 1.04), and -.94 (-1.66 to -.16) compared with control groups in terms of triglycerides, total cholesterol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) concentrations, respectively. In adult overweight patients with or without diabetes, SAGB and SG are most effective at ameliorating insulin resistance. SAGB, Roux-en-Y gastric bypass + omentectomy, and DS are useful for reducing triglycerides, total cholesterol, and LDL-C. SG + omentectomy elevates HDL-C concentrations best. Adjustable gastric band and biliopancreatic diversion may not control insulin resistance or dyslipidemia well.

Faecal Inflammatory Biomarkers and Gastrointestinal Symptoms after Bariatric Surgery: A Longitudinal Study

Background

Bariatric surgery induces various gastrointestinal (GI) modifications. We performed the first study longitudinally assessing the effect of bariatric surgery on faecal inflammatory biomarker levels and its relation with GI complaints.

Method

Faecal calprotectin, lactoferrin, and calgranulin-C levels were determined in 41 patients (34 Roux-en-Y [RYGB], 7 sleeves) before and at 6-16 weeks, 6 months, and 1 year after surgery. Changes in biomarker levels and percentage of patients above reference value were determined. Gastrointestinal symptom rating scale (GSRS) was used to assess GI complaints at corresponding time points. The postoperative relation between GSRS score and biomarker levels above reference value was investigated.

Results

After RYGB, median calprotectin levels are significantly higher (>188, 104-415 μg/g) than before surgery (40, 19-78 μg/g; p < 0.001), and over 90% of patients have levels above reference value 1 year after surgery. Median lactoferrin was 0.4 (0.2-1.6) μg/g before, and >5.9 (1.8-13.6) μg/g after surgery (p < 0.001). Median calgranulin-C levels remained far below the reference value and were 0.13 (0.05-0.24) μg/g before and <0.23 (0.06-0.33) μg/g after surgery. Similar results were found after sleeve gastrectomy. No difference was seen in GSRS score for patients with calprotectin and lactoferrin levels above reference values.

Conclusion

Faecal inflammatory biomarkers calprotectin and lactoferrin, but not calgranulin-C, rise above reference values shortly after bariatric surgery and remain elevated in the majority of patients. The discrepancy between calprotectin and calgranulin-C levels suggests no GI inflammation. Furthermore, patients after RYGB with biomarkers above the population reference value do not seem to have more GI complaints.

Adaptations in gastrointestinal physiology after sleeve gastrectomy and Roux-en-Y gastric bypass

Linked to the growing obesity epidemic, demand for bariatric and metabolic surgery has increased, the most common procedures being sleeve gastrectomy and Roux-en-Y gastric bypass. Originally, bariatric procedures were described as purely restrictive, malabsorptive, or combined restrictive-malabsorptive procedures limiting food intake, nutrient absorption, or both. Nowadays, anatomical alterations are known to affect gastrointestinal physiology, which in turn affects the digestion and absorption of nutrients and drugs. Therefore, understanding gastrointestinal physiology is crucial to prevent postoperative nutritional deficiencies and to optimise postoperative drug therapy. Preclinical and clinical research indicates that sleeve gastrectomy accelerates liquid and solid gastric emptying and small intestinal transit, and increases bile acid serum levels, whereas its effects on gastrointestinal acidity, gastric and pancreatic secretions, surface area, and colonic transit remain largely unknown. Roux-en-Y gastric bypass diminishes gastric acid secretion, accelerates liquid gastric emptying, and increases bile acid serum levels, but its effects on intestinal pH, solid gastric emptying, intestinal transit time, gastric enzyme secretions, and surface area remain largely unknown. In this Review, we summarise current knowledge of the effects of these two procedures on gastrointestinal physiology and assess the knowledge gaps.

Do Gut Hormones Contribute to Weight Loss and Glycaemic Outcomes after Bariatric Surgery?

Bariatric surgery is an effective intervention for management of obesity through treating dysregulated appetite and achieving long-term weight loss maintenance. Moreover, significant changes in glucose homeostasis are observed after bariatric surgery including, in some cases, type 2 diabetes remission from the early postoperative period and postprandial hypoglycaemia. Levels of a number of gut hormones are dramatically increased from the early period after Roux-en-Y gastric bypass and sleeve gastrectomy—the two most commonly performed bariatric procedures—and they have been suggested as important mediators of the observed changes in eating behaviour and glucose homeostasis postoperatively. In this review, we summarise the current evidence from human studies on the alterations of gut hormones after bariatric surgery and their impact on clinical outcomes postoperatively. Studies which assess the role of gut hormones after bariatric surgery on food intake, hunger, satiety and glucose homeostasis through octreotide use (a non-specific inhibitor of gut hormone secretion) as well as with exendin 9–39 (a specific glucagon-like peptide-1 receptor antagonist) are reviewed. The potential use of gut hormones as biomarkers of successful outcomes of bariatric surgery is also evaluated.

Laparoscopic Sleeve Gastrectomy Versus Laparoscopic Roux-en-Y Gastric Bypass: A Systematic Review and Meta-analysis of Weight Loss, Comorbidities, and Biochemical Outcomes From Randomized Controlled Trials

OBJECTIVE

The aim of this study was to compare weight loss, obesity-related comorbidities, and biochemical outcomes of LSG versus LRYGB through a meta-analysis of randomized controlled trials (RCTs).

SUMMARY OF BACKGROUND DATA

LSG and LRYGB are the 2 most commonly performed bariatric surgeries for the treatment of obesity. The comparative outcomes of the 2 surgeries is a topic of ongoing debate and medium-term outcomes remain uncertain.

METHODS

A search for RCTs comparing LRYGB versus LSG was conducted. Pooled outcomes between 2 procedures were compared using pairwise random-effects meta-analysis at 1, 3, and 5-year follow-up time points. Grading of recommendations, assessment, development, and evaluation was used to assess certainty of evidence.

RESULTS

Thirty-three studies involving 2475 patients were included. LRYGB resulted in greater loss of body mass index compared to LSG at 1 year [mean difference -1.25 kg/m2, 95% confidence interval (CI) -2.01 to -0.49, P = 0.001; moderate certainty of evidence] which persisted at 3 years, but there was insufficient evidence at 5 years. Resolution of dyslipidemia was higher for LRYGB than LSG at 1 year (risk ratio 0.58, 95% CI 0.46-0.73, P < 0.001; moderate certainty of evidence) and 5 years (risk ratio 0.68, 95%CI 0.46-0.99, P = 0.04; low certainty of evidence). There was no difference between LRYGB and LSG for remission of type 2 diabetes, hypertension, and hemoglobin A1c, fasting insulin, homeostatic model assessment of insulin resistance, high-density lipoprotein, and the rate of 30-day major and minor complications.

CONCLUSIONS

There are insufficient data from RCTs to draw any conclusions regarding the long-term comparative effectiveness beyond 3 years between LRYGB and LSG.

Changes in fasting bile acid profiles after Roux-en-Y gastric bypass and sleeve gastrectomy

BACKGROUND

Bile acid is an essential factor that plays a role in metabolic regulation, but how bile acid is regulated after Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) remains unclear. This meta-analysis aimed to investigate changes in the levels of fasting bile acids following RYGB and SG.

METHODS

A systematic literature search of the PubMed, EMBASE, Cochrane Library and Web of Science databases through July 2020 was performed in accordance with the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The concentrations of bile acids were evaluated.

RESULTS

Thirteen studies with 289 patients were included. Our results showed that patients who underwent RYGB had increased levels of fasting total bile acids, primary bile acids, secondary bile acids, conjugated bile acids, and unconjugated bile acids, but no significant differences in all these bile acid levels were observed in patients who underwent SG. Furthermore, 12a-hydroxylated bile acid levels and the 12a-hydroxylated/non-12a-hydroxylated bile acid ratio also increased following RYGB.

CONCLUSION

In this study, we found that fasting bile acid levels, especially 12a-hydroxylated bile acids levels, were increased after RYGB. However, no differences in fasting bile acid levels were observed following SG.

Altered bile acid kinetics contribute to postprandial hypoglycaemia after Roux-en-Y gastric bypass surgery

BACKGROUND/OBJECTIVES

Bile acids (BA) act as detergents in intestinal fat absorption and as modulators of metabolic processes via activation of receptors such as FXR and TGR5. Elevated plasma BA as well as increased intestinal BA signalling to promote GLP-1 release have been implicated in beneficial health effects of Roux-en-Y gastric bypass surgery (RYGB). Whether BA also contribute to the postprandial hypoglycaemia that is frequently observed post-RYGB is unknown.

METHODS

Plasma BA, fibroblast growth factor 19 (FGF19), 7α-hydroxy-4-cholesten-3-one (C4), GLP-1, insulin and glucose levels were determined during 3.5 h mixed-meal tolerance tests (MMTT) in subjects after RYGB, either with (RYGB, n = 11) or without a functioning gallbladder due to cholecystectomy (RYGB-CC, n = 11). Basal values were compared to those of age, BMI and sex-matched obese controls without RYGB (n = 22).

RESULTS

Fasting BA as well as FGF19 levels were elevated in RYGB and RYGB-CC subjects compared to non-bariatric controls, without significant differences between RYGB and RYGB-CC. Postprandial hypoglycaemia was observed in 8/11 RYGB-CC and only in 3/11 RYGB. Subjects who developed hypoglycaemia showed higher postprandial BA levels coinciding with augmented GLP-1 and insulin responses during the MMTT. The nadir of plasma glucose concentrations after meals showed a negative relationship with postprandial BA peaks. Plasma C4 was lower during MMTT in subjects experiencing hypoglycaemia, indicating lower hepatic BA synthesis. Computer simulations revealed that altered intestinal transit underlies the occurrence of exaggerated postprandial BA responses in hypoglycaemic subjects.

CONCLUSION

Altered BA kinetics upon ingestion of a meal, as frequently observed in RYGB-CC subjects, appear to contribute to postprandial hypoglycaemia by stimulating intestinal GLP-1 release.

Effect of Lactobacillus rhamnosus Probiotic in Early Pregnancy on Plasma Conjugated Bile Acids in a Randomised Controlled Trial

We have previously shown that probiotic supplementation with Lactobacillus rhamnosus HN001 (HN001) led to a reduced incidence of gestational diabetes mellitus (GDM). Here we investigate whether HN001 supplementation resulted in alterations in fasting lipids, insulin resistance, or bile acids (BAs) during pregnancy. Fasting plasma samples collected at 24-30 weeks' gestation, from 348 women randomised at 14-16 weeks' gestation to consume daily probiotic HN001 (n = 172) or a placebo (n = 176) were analysed for lipids, insulin, glucose and BAs. Women supplemented with HN001 had lower fasting glucose compared with placebo (p = 0.040), and lower GDM. Significant differences were found in fasting insulin, HOMA-IR, low density lipoprotein-cholesterol (LDL-c), high density lipoprotein (HDL)-c, triglycerides, total cholesterol, and BAs by GDM status. Lower fasting conjugated BAs were seen in women receiving HN001. A significant decrease of glycocholic acid (GCA) was found in older (age ≥ 35) women who received HN001 (p = 0.005), while GDM women showed significant reduced taurodeoxycholic acid (TDCA) (p = 0.018). Fasting conjugated BA was positively correlated with fasting glucose (r = 0.136, p = 0.020) and fasting insulin (r = 0.113, p = 0.036). Probiotic HN001 supplementation decreases conjugated BAs and might play a role in the improvement of glucose metabolism in women with pregnancy.

Untargeted metabolomics reveals plasma metabolites predictive of ectopic fat in pancreas and liver as assessed by magnetic resonance imaging: the TOFI_Asia study

BACKGROUND

Excess visceral obesity and ectopic organ fat is associated with increased risk of cardiometabolic disease. However, circulating markers for early detection of ectopic fat, particularly pancreas and liver, are lacking.

METHODS

Lipid storage in pancreas, liver, abdominal subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) from 68 healthy or pre-diabetic Caucasian and Chinese women enroled in the TOFI_Asia study was assessed by magnetic resonance imaging/spectroscopy (MRI/S). Plasma metabolites were measured with untargeted liquid chromatography-mass spectroscopy (LC-MS). Multivariate partial least squares (PLS) regression identified metabolites predictive of VAT/SAT and ectopic fat; univariate linear regression adjusting for potential covariates identified individual metabolites associated with VAT/SAT and ectopic fat; linear regression adjusted for ethnicity identified clinical and anthropometric correlates for each fat depot.

RESULTS

PLS identified 56, 64 and 31 metabolites which jointly predicted pancreatic fat (R2Y = 0.81, Q2 = 0.69), liver fat (RY2 = 0.8, Q2 = 0.66) and VAT/SAT ((R2Y = 0.7, Q2 = 0.62)) respectively. Among the PLS-identified metabolites, none of them remained significantly associated with pancreatic fat after adjusting for all covariates. Dihydrosphingomyelin (dhSM(d36:0)), 3 phosphatidylethanolamines, 5 diacylglycerols (DG) and 40 triacylglycerols (TG) were associated with liver fat independent of covariates. Three DGs and 12 TGs were associated with VAT/SAT independent of covariates. Notably, comparison with clinical correlates showed better predictivity of ectopic fat by these PLS-identified plasma metabolite markers.

CONCLUSIONS

Untargeted metabolomics identified candidate markers of visceral and ectopic fat that improved fat level prediction over clinical markers. Several plasma metabolites were associated with level of liver fat and VAT/SAT ratio independent of age, total and visceral adiposity, whereas pancreatic fat deposition was only associated with increased sulfolithocholic acid independent of adiposity-related parameters, but not age.

Recent advances in the mechanisms underlying the beneficial effects of bariatric and metabolic surgery

Bariatric and metabolic surgery (BMS) is the most effective treatment for obesity, type 2 diabetes and co-morbidities, including nonalcoholic fatty liver disease and nonalcoholic steatohepatitis. The beneficial effects of BMS are beyond the primary goal of gastric restriction and nutrients malabsorption. Roux-en-Y gastric bypass and vertical sleeve gastrectomy are the 2 most commonly performed procedures of BMS. Both surgeries lead to physiologic changes in gastrointestinal tract; subsequently alter bile acids pool and composition, gut microbial activities, gut hormones, and circulating exosomes; and ultimately contribute to the improved glycemic control, insulin sensitivity, lipid metabolism, energy expenditure, and weight loss. The mechanisms underlying the benefits of BMS likely involve the bile acid-signaling pathway mediated mainly by nuclear farnesoid X receptor and the membrane Takeda G protein-coupled receptor, bile acids-gut microbiota interaction, and exosomes. In this review, we focus on recent advances in potential mechanisms and aim to learn novel insights into the molecular mechanisms underlying metabolic disorders.

Potential contribution of the gut microbiota to hypoglycemia after gastric bypass surgery

Obesity has become a global health problem. Lifestyle modification and medical treatment only appear to yield short-term weight loss. Roux-en-Y gastric bypass (RYGB) is the most popular bariatric procedure, and it sustains weight reduction and results in the remission of obesity-associated comorbidities for obese individuals. However, patients who undergo this surgery may develop hypoglycemia. To date, the diagnosis is challenging and the prevalence of post-RYGB hypoglycemia (PRH) is unclear. RYGB alters the anatomy of the upper gastrointestinal tract and has a combined effect of caloric intake restriction and nutrient malabsorption. Nevertheless, the physiologic changes after RYGB are complex. Although hyperinsulinemia, incretin effects, dysfunction of β-cells and α-cells, and some other factors have been widely investigated and are reported to be possible mediators of PRH, the pathogenesis is still not completely understood. In light of the important role of the gut microbiome in metabolism, we hypothesized that the gut microbiome might also be a critical link between RYGB and hypoglycemia. In this review, we mainly highlight the current possible factors predisposing individuals to PRH, particularly related to the gut microbiota, which may yield significant insights into the intestinal regulation of glucose metabolic homeostasis and provide novel clues to improve the treatment of type 2 diabetes mellitus.

Effect of bariatric surgery on circulating FGF-19: A systematic review and meta-analysis

Fibroblast growth factor-19 (FGF-19) is a gut hormone which interacts with metabolism and is depleted in obesity. There is some indication that the hormone undergoes a resurgence following bariatric surgery (BS), an effect which may contribute to the beneficial outcomes of such procedures. This systematic review and meta-analysis aims to synthesize the available literature on FGF-19 levels before and after BS. MEDLINE, Scopus and Web of Science databases were searched, and the effect of different surgical procedures and degrees of body mass index (BMI) reduction on FGF-19 levels was assessed by DerSimonian and Laird random-effects model in meta-analysis and dose-response analyses. This meta-analysis, which included 474 patients from 25 arms undergoing one of five BS procedures, revealed a significant increase in the levels of circulating FGF-19 following all-type BS. Vertical sleeve gastrectomy, duodenal-jejunal bypass liner and Roux-en-Y gastric bypass all significantly increased circulating FGF-19 levels from baseline. However, gastric banding failed to achieve the same, and in fact, biliopancreatic diversion was associated with decreased circulating FGF-19. Finally, an inverse association between FGF-19 and the degree of BMI-reduction post-operatively was noted. FGF-19 is increased by BS and may represent a pharmaceutical target in efforts to reproduce the beneficial effects of BS in a medical setting.