Intestinal peptide changes after bariatric and minimally invasive surgery: Relation to diabetes remission

Role of the Intestine and Its Gut Microbiota in Metabolic Syndrome and Obesity

The metabolic syndrome (MetSyn) is currently one of the biggest global health challenges because of its impact on public health. MetSyn includes the cluster of metabolic disorders including obesity, high blood pressure, hyperglycemia, high triglyceride levels, and hepatic steatosis. Together, these abnormalities increase the cardiovascular risk of individuals and pose a threat to healthcare systems worldwide. To better understand and address this complex issue, recent research has been increasingly focusing on unraveling the delicate interplay between metabolic disorders and the intestines and more specifically our gut microbiome. The gut microbiome entails all microorganisms inhabiting the gastrointestinal tract and plays a pivotal role in metabolic processes and overall health of its host. Emerging evidence proves an association between the gut microbiome composition and aspects of MetSyn, such as obesity. Understanding these relationships is crucial because they offer valuable insights into the mechanisms underlying development and progression of metabolic disorders and possible treatment options. Yet, how should we interpret this relationship? This review focuses on the interplay between the gut and MetSyn. In addition, we have reviewed the existing evidence of the gut microbiome and its association with and impact on metabolic disorders, in an attempt to understand the complex interactions and nature of this association. We also explored potential therapeutic options targeting the gut to modify metabolic disorders and obesity.

Recellularization via electroporation therapy of the duodenum combined with glucagon-like peptide 1 receptor agonist to replace insulin therapy in patients with type 2 diabetes: 12-month results of a first-in-human study

BACKGROUND AND AIMS

Studies have shown that hydrothermal duodenal mucosal ablation results in improved glycemic control. Recellularization via electroporation therapy (ReCET) is a novel endoscopic procedure that uses electroporation to induce cellular apoptosis and subsequent reepithelization. In this study, we aimed to eliminate exogenous insulin treatment in type 2 diabetes (T2D) patients through a single ReCET procedure combined with a glucagon-like peptide 1 receptor agonist. Feasibility, safety, and (dose) efficacy of ReCET were assessed.

METHODS

This first-in-human study included patients with T2D on basal insulin (age, 28-75 years; body mass index, 24-40 kg/m2; glycosylated hemoglobin, ≤64 mmol/mol; C-peptide, ≥0.2 nmol/L). The electroporation dose was optimized during the study, starting with single 600 V and ending with double 750 V treatments. All patients underwent ReCET, after which insulin was discontinued and semaglutide (glucagon-like peptide-1 receptor agonist) was initiated. The primary endpoints were feasibility (procedure time [from catheter in to catheter out], technical success rate), safety, and efficacy (patients off insulin at 6 months; HbA1c, ≤58 mmol/mol).

RESULTS

Fourteen patients underwent endoscopic ReCET. The median procedure time was 58 (interquartile range, 49-73) minutes. ReCET demonstrated a technical success rate of 100%. No device-related severe adverse events or severe hypoglycemic events were observed. At the 12-month follow-up, 12 (86%) patients remained off exogenous insulin therapy, with significant improvements in glycemic control and metabolic parameters. The 2 patients in whom insulin therapy was reintroduced both received ReCET at the lowest voltage (single 600 V).

CONCLUSION

These results suggest that ReCET is feasible and safe. In combination with semaglutide, ReCET may be a promising therapeutic option to replace insulin therapy in selected T2D patients while improving glycemic control and metabolic health.

Contemporary Clinical Perspectives on Targeting Remission of Type 2 Diabetes

It has long been known that some patients with type 2 diabetes (T2DM) can experience sustained metabolic improvement to near-normal levels of glycemia either spontaneously or after medical intervention. Now recognized as remission of diabetes, this intriguing state is currently more feasible than ever before due to profound advances in metabolic surgery, pharmacologic therapy, and regimens of lifestyle modification. This enhanced capacity to induce remission has revealed new pathophysiologic insights, including the presence of a reversible component of the pancreatic beta-cell dysfunction that otherwise drives the chronic progressive nature of T2DM. In doing so, it has changed the therapeutic landscape by offering new potential management objectives and considerations for patients and providers. However, the excitement around these developments must also be tempered by the sobering realities of our current understanding of remission, including the recognition that this condition may not be permanent (resulting in glycemic relapse over time) and that beta-cell function may not be normalized in the setting of remission. These limitations highlight both the many gaps in our current understanding of remission and the caution with which clinical discussions must be handled for clear patient-directed communication of the pros and cons of targeting this outcome in practice. In this mini-review, we consider this rapidly growing literature, including its implications and its limitations, and thereby seek to provide objective balanced perspectives on targeting remission of T2DM in current clinical care.

Intestinal heat shock proteins in metabolic syndrome: Novel mediators of obesity and its comorbidities resolution after metabolic surgery

Over the past 40 years, the prevalence of obesity has risen dramatically, reaching epidemic proportions. Metabolic surgery has proven to be highly effective in treating obesity, leading to significant improvements or complete resolution of obesity-related comorbidities. Research conducted in both animals and humans suggests that the metabolic benefits achieved through metabolic surgery cannot be solely attributed to weight loss. Indeed, there has been an increasing recognition of intestinal inflammation as a novel factor influencing obesity. The gastrointestinal tract is continuously exposed to dietary components, particularly diets rich in saturated fats, which are known to contribute to obesity. It is now widely accepted that heat shock proteins can be released from various cells including intestinal epithelial cells and act as proinflammatory signals. Several studies have shown that circulating levels of glucose-regulated protein 78 (GRP78) are increased in subjects with obesity and correlate with the severity of the disease. Moreover, mice with a partial knockout of GRP78 are protected from diet-induced obesity. In this review, we discuss the role of GRP78 in the development of obesity. Several evidence suggests that GRP78 can influence adipogenesis, lipid droplets stabilization, insulin resistance, and liver steatosis. We also provide an update on GRP78 regulation following metabolic surgery, focusing on the bypass of the small intestine as a key factor for GRP78 secretion. Finally, we discuss the potential role of monoclonal antibodies against GRP78 as a treatment for obesity.

Upper gut heat shock proteins HSP70 and GRP78 promote insulin resistance, hyperglycemia, and non-alcoholic steatohepatitis

A high-fat diet increases the risk of insulin resistance, type-2 diabetes, and non-alcoholic steato-hepatitis. Here we identified two heat-shock proteins, Heat-Shock-Protein70 and Glucose-Regulated Protein78, which are increased in the jejunum of rats on a high-fat diet. We demonstrated a causal link between these proteins and hepatic and whole-body insulin-resistance, as well as the metabolic response to bariatric/metabolic surgery. Long-term continuous infusion of Heat-Shock-Protein70 and Glucose-Regulated Protein78 caused insulin-resistance, hyperglycemia, and non-alcoholic steato-hepatitis in rats on a chow diet, while in rats on a high-fat diet continuous infusion of monoclonal antibodies reversed these phenotypes, mimicking metabolic surgery. Infusion of these proteins or their antibodies was also associated with shifts in fecal microbiota composition. Serum levels of Heat-Shock-Protein70 and Glucose-Regulated Protein78were elevated in patients with non-alcoholic steato-hepatitis, but decreased following metabolic surgery. Understanding the intestinal regulation of metabolism may provide options to reverse metabolic diseases.

The Role of Beta Cell Recovery in Type 2 Diabetes Remission

Type 2 diabetes (T2D) has been considered a relentlessly worsening disease, due to the progressive deterioration of the pancreatic beta cell functional mass. Recent evidence indicates, however, that remission of T2D may occur in variable proportions of patients after specific treatments that are associated with recovery of beta cell function. Here we review the available information on the recovery of beta cells in (a) non-diabetic individuals previously exposed to metabolic stress; (b) T2D patients following low-calorie diets, pharmacological therapies or bariatric surgery; (c) human islets isolated from non-diabetic organ donors that recover from "lipo-glucotoxic" conditions; and (d) human islets isolated from T2D organ donors and exposed to specific treatments. The improvement of insulin secretion reported by these studies and the associated molecular traits unveil the possibility to promote T2D remission by directly targeting pancreatic beta cells.

Current Status of Metabolic/Bariatric Surgery in Type 1 Diabetes Mellitus: an Updated Systematic Review and Meta-analysis

This systematic review and meta-analysis intend to evaluate the efficacy of metabolic/bariatric surgeries (MBS) in patients with type-1 diabetes mellitus. A systematic literature search and meta-analysis were performed in electronic databases up to July 2021. In total, 27 primary studies comprising 648 subjects were included in this systematic review and meta-analysis. Patients had a mean age of 38.0 ± 7.3 years. Preoperative mean BMI was 42.6 ± 4.7 kg/m² and 29.4 ± 4.7 kg/m² after surgery, respectively. Following bariatric surgeries in patients with type 1 diabetes mellitus, insulin (unit/day) decreased by a weighted mean difference (WMD) of - 10.59. Also, insulin (unit/kg/day) decreased by a WMD of - 0.2, and HbA1C decreased by a WMD of - 0.71, showing MBS acceptable and durable effects of bariatric surgical procedures.

Bariatric/Metabolic Surgery

Bariatric surgery is a gastro-intestinal surgery aimed at obtaining weight loss in obesity. The rapid metabolic effects of this type of operations provided a rational to change its name to metabolic surgery, in fact often the improvement of metabolic diseases is observed before a meaningful weight reduction.In this review, we examine the effects of laparoscopic metabolic surgery on life expectancy, type 2 diabetes, hypertension, cardiovascular disease and cancer.Furthermore, we review the surgical endoscopy approaches to obesity including primary obesity procedures and revision procedures that address weight regain after bariatric surgery.Finally, as a bridge to the specific chapter, we summarize the effects on weight reduction of new anti-obesity medications.

GORD and Barrett's oesophagus after bariatric procedures: multicentre prospective study

INTRODUCTION

Gastro-oesophageal reflux disease (GORD) after bariatric surgery is a debated topic. This study investigated the prevalence of GORD and associated oesophageal complications following bariatric procedures-namely, adjustable gastric banding (AGB), sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), and one-anastomosis gastric bypass (OAGB).

METHODS

This was a prospective multicentre study designed to evaluate the long-term effects of bariatric surgery on GORD. Patients were studied at baseline, at >10 years following AGB, SG, and RYGB, and at >3 years following OAGB (due to the more recent recognition of OAGB as a standard bariatric procedure). Patients were assessed by endoscopy and GORD symptom evaluation.

RESULTS

A total of 241 patients were enrolled. A minimum follow-up of 10 years was completed by 193 patients following AGB (57 patients), SG (95 patients), and RYGB (41 patients), and of >3 years by 48 subjects following OAGB. GORD symptoms increased following AGB and SG (from 14 to 31.6 per cent and from 26.3 to 58.9 per cent, respectively; P < 0.0001), improved following RYGB (from 36.6 to 14.6 per cent; P < 0.0001), and were unchanged following OAGB. The overall prevalence of erosive oesophagitis was greater in the SG group (74.7 per cent) than in the AGB (42.1 per cent), RYGB (22 per cent), and OAGB (22.9 per cent) groups (P < 0.0001). Barrett's oesophagus was found only in patients who had SG (16.8 per cent). Biliary-like gastric stagnation was found in a greater proportion of SG and OAGB patients (79.7 and 69.4 per cent, respectively) than in other treatment groups (P < 0.0001). The prevalence of biliary-type reflux into the oesophagus was higher in patients who underwent SG (74.7 per cent), compared with other treatment groups.

CONCLUSION

Bariatric surgery leads to gastro-oesophageal complications of variable severity, particularly SG, which can result in a large proportion of patients developing Barrett's oesophagus.

Duodenal mucosal resurfacing combined with glucagon-like peptide-1 receptor agonism to discontinue insulin in type 2 diabetes: a feasibility study

BACKGROUND AND AIMS

Duodenal mucosal resurfacing (DMR) is an endoscopic intervention in which the duodenal mucosa is ablated by hydrothermal energy. DMR improves glycemic control in patients with type 2 diabetes (T2D), most likely by altered duodenal signaling leading to insulin sensitization. We studied whether we could discontinue insulin use in T2D patients by combining DMR with glucagon-like peptide-1 receptor agonist (GLP-1RA) and lifestyle counseling.

METHODS

In this single-arm, single-center feasibility study in 16 insulin-treated patients with T2D (hemoglobin A1c [HbA1c] ≤8.0%, basal insulin <1 U/kg/day, C-peptide ≥.5 nmol/L), patients underwent a single DMR followed by a 2-week postprocedural diet, after which GLP-1RA (liraglutide) was introduced. Lifestyle counseling was provided per American Diabetes Association guidelines. The primary endpoint was percentage of patients without insulin with an HbA1c ≤7.5% (responders) at 6 months. Secondary endpoints were changes in multiple glycemic and metabolic parameters and percentage of responders at 12 and 18 months, respectively.

RESULTS

All 16 patients underwent successful DMR without procedure-related serious adverse events. At 6 months, 69% of patients were off insulin therapy with an HbA1c ≤7.5%. At 12 and 18 months 56% and 53% remained off insulin, respectively. All patients significantly improved in the glycemic and metabolic parameters of homeostatic model assessment for insulin resistance, body mass index, weight, and liver fat fraction.

CONCLUSIONS

In this feasibility study, the combination of a single DMR and GLP-1RA, supported by lifestyle counseling, eliminated the need for insulin therapy in most patients with T2D through 18 months postprocedure, with adequate beta-cell capacity, while improving glucose regulation and metabolic health in all patients. A randomized-sham controlled trial is currently initiated based on these results. (Clinical trial registration number: EudraCT 2017-00349-30.).

Comparing the Anti-diabetic Effect of Sleeve Gastrectomy with Transit Bipartition Against Sleeve Gastrectomy and Roux-en-Y Gastric Bypass Using a Diabetic Rodent Model

PURPOSE

Roux-en-Y gastric bypass (RYGB) has superior long-term diabetes remission outcomes to sleeve gastrectomy (SG). However, in regions with a high prevalence of gastric cancer, RYGB may not be the best option. This study aimed to investigate the anti-diabetic effect of SG with transit bipartition (SG-TB) compared with SG and RYGB.

MATERIALS AND METHODS

A total of 32 diabetic Sprague-Dawley rat models were assigned to one of four groups: SG (n = 8), RYGB (n = 8), SG-TB (n = 8), and SHAM (n = 8). Body weight, food intake, blood glucose, and hormonal changes (glucagon-like peptide-1 (GLP-1), insulin, and glucagon) were measured to investigate the effect of surgery in all groups. Oral glucose tolerance test and insulin tolerance test were performed before and 8 weeks after surgery.

RESULTS

There were no significant differences in the postoperative changes in body weight and food intake among the SG, RYGB, and SG-TB groups. Postoperatively, the RYGB and SG-TB groups had significantly higher GLP-1 levels and lower insulin levels than the SG group. Further, RYGB and SG-TB had significantly better glucose control improvements than SG. There were no significant differences in GLP-1, insulin, glucagon, and homeostasis model assessment of insulin resistance levels between RYGB and SG-TB. The preoperative and postoperative values of all variables in the SHAM group did not show significant differences.

CONCLUSION

In this study using a diabetes-induced rodent model, we found that the anti-diabetic effect of SG-TB is superior to that of SG and non-inferior to that of RYGB.

Modulation of Food Intake by Differential TAS2R Stimulation in Rat

Metabolic surgery modulates the enterohormone profile, which leads, among other effects, to changes in food intake. Bitter taste receptors (TAS2Rs) have been identified in the gastrointestinal tract and specific stimulation of these has been linked to the control of ghrelin secretion. We hypothesize that optimal stimulation of TAS2Rs could help to modulate enteroendocrine secretions and thus regulate food intake. To determine this, we have assayed the response to specific agonists for hTAS2R5, hTAS2R14 and hTAS2R39 on enteroendocrine secretions from intestinal segments and food intake in rats. We found that hTAS2R5 agonists stimulate glucagon-like peptide 1 (GLP-1) and cholecystokinin (CCK), and reduce food intake. hTAS2R14 agonists induce GLP1, while hTASR39 agonists tend to increase peptide YY (PYY) but fail to reduce food intake. The effect of simultaneously activating several receptors is heterogeneous depending on the relative affinity of the agonists for each receptor. Although detailed mechanisms are not clear, bitter compounds can stimulate differentially enteroendocrine secretions that modulate food intake in rats.

Emerging role of GIP and related gut hormones in fertility and PCOS

Gastric inhibitory polypeptide (GIP) is best known as an incretin hormone released by enteroendocrine K-cells in response to feeding and stimulates insulin release to regulate blood glucose and nutrient homeostasis. More recently GIP has been ascribed a positive role in lipid metabolism, bone strength, cardiovascular function and cognition. The present paper considers an emerging role of GIP and related gut hormones in fertility and especially polycystic ovarian syndrome (PCOS). Key evidence concerns restoration of fertility in women with gross obesity and PCOS following bariatric surgery. This is considered to reflect indirect effects mediated by alleviation of insulin resistance together with possible direct effects of surgically induced changes of GIP, GLP-1 and related peptide hormones on ovaries and the hypothalamic-pituitary-adrenal axis. Further studies are required to determine inter-relationships between the hormones and cellular mechanisms involved but these observations suggest that GIP and other gut may provide a novel therapeutic approach for PCOS and other reproductive disorders.

The jejunum is the key factor in insulin resistance

BACKGROUND

Biliopancreatic diversion (BPD) is more effective than Roux-en-Y gastric bypass (RYGB) on both insulin resistance and diabetes.

OBJECTIVES

Because the major difference between the 2 procedures resides in the length of jejunal bypass, we investigated the role of the jejunum in insulin resistance.

SETTING

University hospital in Italy.

METHODS

Insulin sensitivity (IS) and secretion were measured before and 4 weeks after RYGB or BPD in 16 patients. A translational study was also conducted in 6 pigs, by isolating a jejunal loop with its vascular and nerve supply (Thiry-Vella loop [TVL]). TVL was doubly stomatized and bowel continuity restored by a side-to-side jejuno-jejunostomy. At baseline and 4 weeks postoperatively a glucose bolus was injected either in the stomach or in the TVL. Whole-body IS and jejunal heat shock proteins (HSPs) were measured. Primary porcine hepatocyte cultures were incubated with plasma or individual HSPs.

RESULTS

Whole-body IS increased from 353.5 ± 26.7 to 442.0 ± 37.4 (P < .05) after RYGB and from 312.4 ± 14.9 to 441.2 ± 15.9 mL/m^-2/min^-1 (P < .001) after BPD. Hepatic IS was unchanged after RYGB, while it increased from .3 ± .01 to .4 ± .1 (μM/pM) - 1 (P < .01) after BPD. Total insulin secretion rate remained unchanged after RYGB but decreased (from 58.3 ± 23.6 to 33.1 ± 7.8 nmol/m^-2, P < .05) after BPD. Jejunectomy in pigs enhanced IS (.3 ± .01 versus .2 ± .01 mM/pM, P < .001), while injection of glucose into TVL reduced it (.1 ± .01 versus .3 ± .01 mM/pM, P < .0001). The jejunum secreted HSPs, Hsp70, and GRP78, which impaired insulin signaling in hepatocyte cultures.

CONCLUSIONS

This study shows that jejunal bypass in both humans and pigs improves IS. Injection of glucose into the TVL in pigs determines insulin resistance. In response to glucose, the jejunum secretes HSPs that impair insulin signaling.

Multiorgan Systems Study Reveals Igfbp7 as a Suppressor of Gluconeogenesis after Gastric Bypass Surgery

Roux-en-Y gastric bypass (RYGB) surgery reduces weight in obese patients. A marked decrease in blood glucose levels occurs before weight loss; however, key molecules that improve the glycemic profile remain largely unknown. Using a murine RYGB surgery model, we performed multiorgan proteomics and bioinformatics to monitor the proteins and molecular pathways that change in this early glycemic response. Multiplexed proteomic kinetics data analysis revealed that the Roux limb, biliopancreatic limb, liver, and pancreas each exhibited unique temporal and molecular responses to the RYGB surgery. In addition, protein-protein network analysis indicated that the changes to the microbial environment in the intestine may play a crucial role in the beneficial effects of RYGB surgery. Furthermore, insulin-like growth factor binding protein 7 (Igfbp7) was identified as an early induced protein in the Roux limb. Known secretory properties of Igfbp7 prompted us to further investigate its role as a remote organ regulator of glucose metabolism. Igfbp7 overexpression decreased blood glucose levels in diet-induced obese mice and attenuated gluconeogenic gene expression in the liver. Secreted Igfbp7 appeared to mediate these beneficial effects. These results demonstrate that organs responded differentially to RYGB surgery and indicate that Igfbp7 may play an important role in improving blood glucose levels.

Obesity Surgery and Cancer: What Are the Unanswered Questions?

Obesity has become a global epidemic with a soaring economic encumbrance due to its related morbidity and mortality. Amongst obesity-related conditions, cancer is indeed the most redoubtable. Bariatric surgery has been proven to be the most effective treatment for obesity and its associated metabolic and cardiovascular disorders. However, the understanding of whether and how bariatric surgery determines a reduction in cancer risk is limited. Obesity-related malignancies primarily include colorectal and hormone-sensitive (endometrium, breast, prostate) cancers. Additionally, esophago-gastric tumors are growing to be recognized as a new category mainly associated with post-bariatric surgery outcomes. In fact, certain types of surgical procedures have been described to induce the development and subsequent progression of pre-cancerous esophageal and gastric lesions. This emerging category is of great concern and further research is required to possibly prevent such risks. Published data has generated conflicting results. In fact, while overall cancer risk reduction was reported particularly in women, some authors showed no improvement or even increased cancer incidence. Although various studies have reported beneficial effects of surgery on risk of specific cancer development, fundamental insights into the pathogenesis of obesity-related cancer are indispensable to fully elucidate its mechanisms.