The Unconventional Role for Gastric Volume in the Response to Bariatric Surgery for Both Weight Loss and Glucose Lowering

Sleeve gastrectomy morphology and long-term weight-loss and gastroesophageal reflux disease outcomes

BACKGROUND

The relationship between sleeve gastrectomy (SG) morphology and long-term weight-loss and gastroesophageal reflux disease (GERD) outcomes is unknown.

METHODS

All patients (n = 268) undergoing SG performed by 3 surgeons at a single academic institution from January 1, 2010 to December 31, 2012 were included. Long-term weight-loss and GERD outcomes were available for 90 patients which were incorporated in analyses. SG morphology was determined from postoperative day 1 upper gastrointestinal series (UGIS) available from 50 patients. Images were independently categorized using previously published methodology as Dumbbell (38%), Lower Pouch (22%), Tubular (26%), or Upper Pouch (14%) by Radiologist and Surgeon. Radiologist categorization was used when disagreement occurred (8%). Univariable analyses were conducted to explore potential associations between SG morphology, weight loss, and GERD outcomes.

RESULTS

Follow-up was 8.2 ± 0.9 years. Population characteristics included age of 45.1 ± 10.8 years, female sex in 83.3%, and hiatal hernia repair (HHR) performed at index SG in 17.8%. Surgeons did not preferentially achieve a specific SG morphology. Changes from preoperative obesity and associated diseases comprised body mass index (BMI) (49.5 ± 7.6 vs. 39.2 ± 9.4 kg/m²; p < 0.0001), diabetes mellitus (30.0 vs. 12.2%; p = 0.0006), hypertension (70.0 vs. 54.4%; p = 0.0028), hyperlipidemia (42.2 vs. 24.2%;p = 0.0017), obstructive sleep apnea (41.1 vs. 15.6%; p < 0.0001), osteoarthritis (48.9 vs. 13.3%; p < 0.0001), back pain (46.5 vs. 28.9%; p = 0.0035), and medications (4.8 ± 3.3 vs. 3.7 ± 3.5; p < 0.0001). Dumbbell SG morphology was associated with lesser reduction in BMI at follow-up (--6.8 ± 7.2 vs. -12.4 ± 8.3 kg/m²; p = 0.0196) while greater BMI change was appreciated with Lower Pouch SG shape (-16.9 ± 9.9 vs. -8.4 ± 6.8 kg/m²; p = 0.0017). GERD was more prevalent at follow-up than baseline (67.8 vs. 47.8%; p < 0.0001). GERD-specific outcomes included de novo (51.1%), persistent (27.9%), worsened (58.1%), and resolved (14.0%) disease. Ten patients underwent reoperation for refractory GERD with SG morphology corresponding to Dumbbell (n = 5) and Upper Pouch (n = 1) for those with available UGIS. Univariable analyses showed that patients with GERD experienced a larger reduction in BMI compared with patients without GERD (-11.8 ± 7.7 vs. -7.0 ± 5.1 kg/m²; p = 0.0007). Patient age, surgeon, morphology category, and whether a HHR was done at index SG were not associated with the presence of any, de novo, or worsened GERD. Female sex was associated with worsened GERD (96.0 vs. 4.0%; p = 0.0455). Type of calibration device, distance from staple line to pylorus, and whether staple line reinforcement was used were not associated with SG morphology classification.

CONCLUSION

This is the first study assessing the impact of SG morphology on long-term weight loss and GERD. Our data suggest an association between SG morphology and long-term weight loss but not with GERD outcomes. Current technical standards may be limited in reproducing the same SG morphology. This information may help guide the technical optimization and standardization of SG. Surgeons did not favor a specific SG morphology (1). Our results signal to a relationship between radiographic assessment of SG morphology and long-term weight-loss outcomes with Dumbbell classification correlated with lesser reduction in BMI (2a) and Lower Pouch morphology associated with superior weight loss (2b). SG, sleeve gastrectomy; BMI, body mass index.

Bariatric surgery and the neurohormonal switch: Early insulin resistance recordings after laparoscopic sleeve gastrectomy

Laparoscopic sleeve gastrectomy (LSG) is a bariatric operation with a safe risk profile. It has been proven to successfully reduce weight, decrease insulin resistance (IR), and ameliorate diabetes mellitus. The aim of this study was to determine if there is an early improvement in IR after LSG and its association with weight loss. This was a prospective observational study of 32 patients who underwent LSG at a single center over a 3-year period. Serum insulin and fasting glucose levels were recorded preoperatively, on day 1 postoperatively, and 3 weeks after LSG. IR levels were calculated using the Homeostasis Model Assessment 2 Version 2.23. IR levels were compared along with the overall weight loss, via body mass index. β-cell function was the secondary outcome. IR significantly improved the day after surgery with a statistically significant mean difference of 0.89 units (P = .043) and significantly more so 3 weeks postoperatively, with a mean difference of 4.32 units (P < .0005). β-cell function reduced 3 weeks postoperatively, with a mean difference of 23.95 %β (P = .025), while body mass index significantly reduced, with a mean difference of 4.32 kg/m2 (P < .0005). Early improvement of IR was observed on postoperative day 1 after LSG before any weight loss. This raises the possibility of an undetermined, underlying neurohormonal switch that improves IR. Further investigation is needed to determine this mechanism, as it may lead to an improvement in the medical management of diabetes mellitus.

Advances in the application of mesenchymal stem cells, exosomes, biomimetic materials, and 3D printing in osteoporosis treatment

Owing to an increase in the aging population, osteoporosis has become a severe public health concern, with a high prevalence among the elderly and postmenopausal adults. Osteoporosis-related fracture is a major cause of morbidity and mortality in elderly and postmenopausal adults, posing a considerable socioeconomic burden. However, existing treatments can only slow down the process of osteoporosis, reduce the risk of fractures, and repair fractures locally. Therefore, emerging methods for treating osteoporosis, such as mesenchymal stem cell transplantation, exosome-driving drug delivery systems, biomimetic materials, and 3D printing technology, have received increasing research attention, with significant progress. Mesenchymal stem cells (MSCs) are pluripotent stem cells that can differentiate into different types of functional cells. Exosomes play a key role in regulating cell microenvironments through paracrine mechanisms. Bionic materials and 3D printed scaffolds are beneficial for the reconstruction and repair of osteoporotic bones and osteoporosis-related fractures. Stem cells, exosomes, and biomimetic materials represent emerging technologies for osteoporosis treatment. This review summarizes the latest developments in these three aspects.

The Role of Elevated Branched-Chain Amino Acids in the Effects of Vertical Sleeve Gastrectomy to Reduce Weight and Improve Glucose Regulation

Elevated levels of branched-chain amino acids (BCAAs) and their metabolites are strongly positively associated with obesity, insulin resistance, and type 2 diabetes. Bariatric surgery is among the best treatments for weight loss and associated morbidities. Clinical studies have reported that bariatric surgery decreases the circulating levels of BCAAs. The objective of this study was to test the hypothesis that reduced BCAA levels contribute to the metabolic improvements of sustained weight loss and improved glucose tolerance after vertical sleeve gastrectomy (VSG). We find that, as in humans, circulating BCAAs are significantly lower in VSG rats and mice. To increase circulating BCAAs, we tested mice with either increased dietary intake of BCAAs or impaired BCAA catabolism by total body deletion of mitochondrial phosphatase 2C (Pp2cm). Our results show that a decrease in circulating BCAAs is not necessary for sustained body weight loss and improved glucose tolerance after VSG.

Increased branched-chain amino acid (BCAA) levels are biomarkers of metabolic disease, and bariatric surgeries reduce BCAA levels. Bozadjieva Kramer et al. show that both dietary and genetic manipulations can block the surgical effect on BCAAs but do not alter potent, beneficial effects on weight loss and glucose tolerance.

Intestinal-derived FGF15 protects against deleterious effects of vertical sleeve gastrectomy in mice

Bariatric surgeries such as the Vertical Sleeve Gastrectomy (VSG) are invasive but provide the most effective improvements in obesity and Type 2 diabetes. We hypothesized a potential role for the gut hormone Fibroblast-Growth Factor 15/19 which is increased after VSG and pharmacologically can improve energy homeostasis and glucose handling. We generated intestinal-specific FGF15 knockout (FGF15^INT-KO) mice which were maintained on high-fat diet. FGF15^INT-KO mice lost more weight after VSG as a result of increased lean tissue loss. FGF15^INT-KO mice also lost more bone density and bone marrow adipose tissue after VSG. The effect of VSG to improve glucose tolerance was also absent in FGF15^INT-KO. VSG resulted in increased plasma bile acid levels but were considerably higher in VSG-FGF15^INT-KO mice. These data point to an important role after VSG for intestinal FGF15 to protect the organism from deleterious effects of VSG potentially by limiting the increase in circulating bile acids.

The mechanisms that mediate the effects of weight loss surgeries such as vertical sleeve gastrectomy (VSG) are incompletely understood. Here the authors show that intestinal FGF15 is necessary to improve glucose tolerance and to prevent the loss of muscle and bone mass after VSG, potentially via protection against bile acid toxicity.

The Phantom Satiation Hypothesis of Bariatric Surgery

The excitation of vagal mechanoreceptors located in the stomach wall directly contributes to satiation. Thus, a loss of gastric innervation would normally be expected to result in abrogated satiation, hyperphagia, and unwanted weight gain. While Roux-en-Y-gastric bypass (RYGB) inevitably results in gastric denervation, paradoxically, bypassed subjects continue to experience satiation. Inspired by the literature in neurology on phantom limbs, I propose a new hypothesis in which damage to the stomach innervation during RYGB, including its vagal supply, leads to large-scale maladaptive changes in viscerosensory nerves and connected brain circuits. As a result, satiation may continue to arise, sometimes at exaggerated levels, even in subjects with a denervated or truncated stomach. The same maladaptive changes may also contribute to dysautonomia, unexplained pain, and new emotional responses to eating. I further revisit the metabolic benefits of bariatric surgery, with an emphasis on RYGB, in the light of this phantom satiation hypothesis.

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.

Weight Loss and Changes in Adipose Tissue and Skeletal Muscle Volume after Laparoscopic Sleeve Gastrectomy and Roux-en-Y Gastric Bypass: a Prospective Study with 12-Month Follow-Up

BACKGROUND

This study aimed to evaluate changes in body tissue composition with obesity surgery regarding visceral fat, subcutaneous fat, and skeletal muscle.

DESIGN

Prospective non-randomized single-center cohort study METHODS: Whole-body magnetic resonance imaging (MRI) measured volumes of subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), and skeletal muscle (SM) in 31 patients with laparoscopic sleeve gastrectomy (LSG, 20) or Roux-en-Y gastric bypass (RYGB, 11) preoperatively, at three- and 12-months follow-up.

RESULTS

Body mass index (BMI) went down from 45.2 ± 6.5 preoperatively to 37.2 ± 5.6 (p < 0.001) at three months and 32.2 ± 5.3 kg/m² (p < 0.001) at 12 months. SAT went down from 55.0 ± 14.0 L (liter) to 42.2 ± 13.3 L (p < 0.001) at three months and 31.7 ± 10.5 L (p < 0.001) at 12 months (- 42.3%). VAT went down from 6.5 ± 2.3 to 4.5 ± 1.7 (p < 0.001) at three months and 3.1 ± 1.7 L (p < 0.001) at 12 months (- 52.3%). SM went down from 22.7 ± 4.8 to 20.4 ± 3.6 (p = 0.008) at three months and remained 20.2 ± 4.6 L at 12 months (p = 0.17 relative three-month; p = 0.04 relative preop, - 11.1%). Relative loss was higher for VAT than that for SAT (52.3 ± 18.2% vs. 42.3 ± 13.8%; p = 0.03). At 12 months, there was no difference between LSG and RYGB for relative changes in BMI or body tissue composition.

CONCLUSION

Postoperatively, there was higher net loss of SAT but higher relative loss of VAT with weight loss. SM was lost only during the first three months. MRI provides accurate evaluation of surgeries' effect on individual patients' tissue composition. This can benefit risk assessment for related cardiovascular and metabolic health but cost-related factors will likely reserve the used methods for research.

Endoscopic intragastric balloon: a gimmick or a viable option for obesity?

Worldwide, the prevalence of obesity has doubled since 1980 in 70 countries. More than one in three adults now suffer from overweight or obesity. Health problems related to obesity include orthopedic problems, psychiatric conditions, metabolic and cardiovascular diseases, and of increasing concern, cancer. Thus, obesity has an enormous impact on the individual’s wellbeing as well as on society’s workforce and health care expenses. Medical efforts are ongoing to find safe and effective treatment options for obesity and its metabolic implications. At present, available treatment options include lifestyle interventions, pharmacotherapy, endoscopic applications, and bariatric surgery. Within the range of endoscopic treatment options, the intragastric balloon is the most widely used device. The idea is simple: the gastric volume is reduced by a balloon that is in most cases implanted by an endoscopic procedure similar to a gastroscopy. During the past decades, different models have been developed, which we will briefly introduce in this review. We aim at reviewing the pathophysiology underlying the effect of endoscopic intragastric balloon on weight loss and metabolic changes. We will assess expected short-term and long-term benefits for the patient, and we will discuss common side effects as well as rare complications. We will compare endoscopic intragastric balloon to conservative treatment options with or without pharmacological support on the one hand and to the spectrum of bariatric surgery on the other hand. In most patients, obesity must be considered a chronic disease that requires a lifelong treatment concept. In view of current treatment options for obesity, we will discuss whether endoscopic intragastric balloon is a viable treatment option, and who may be the right patient to benefit from it.