Hydrothermal Duodenal Mucosal Resurfacing: Role in the Treatment of Metabolic Disease

Duodenal enteroendocrine cells and GIP as treatment targets for obesity and type 2 diabetes

The duodenum is an important source of endocrine and paracrine signals controlling digestion and nutrient disposition, notably including the main incretin hormone glucose-dependent insulinotropic polypeptide (GIP). Bariatric procedures that prevent nutrients from contact with the duodenal mucosa are particularly effective interventions to reduce body weight and improve glycaemic control in obesity and type 2 diabetes. These procedures take advantage of increased nutrient delivery to more distal regions of the intestine which enhances secretion of the other incretin hormone glucagon-like peptide-1 (GLP-1). Preclinical experiments have shown that either an increase or a decrease in the secretion or action of GIP can decrease body weight and blood glucose in obesity and non-insulin dependent hyperglycaemia, but clinical studies involving administration of GIP have been inconclusive. However, a synthetic dual agonist peptide (tirzepatide) that exerts agonism at receptors for GIP and GLP-1 has produced marked weight-lowering and glucose-lowering effects in people with obesity and type 2 diabetes. This appears to result from chronic biased agonism in which the novel conformation of the peptide triggers enhanced signalling by the GLP-1 receptor through reduced internalisation while reducing signalling by the GIP receptor directly or via functional antagonism through increased internalisation and degradation.

Update on Endoscopic Treatments for Obesity

PURPOSE OF REVIEW

Increased morbidity seen with rising obesity rates continues to place an unheralded burden on our health system. Lack of higher bariatric surgery utilization and limitations with lifestyle modification and pharmacotherapy highlights the need for additional therapies for obesity. Endoscopic bariatric and metabolic therapies (EBMT) are effective, safe treatments for obesity. Current FDA-approved EBMT are confined to gastric modalities while small bowel directed therapies are still considered investigational. This review highlights current modalities of EBMT.

RECENT FINDINGS

Many randomized controlled trials have been performed, including both open label and sham-controlled, which have demonstrated safety and efficacy of EBMT over lifestyle therapy alone. In addition, emerging evidence from clinical experience further supports EBMT for treatment of obesity. Current evidence supports the safety and efficacy of EBMT for obesity treatment in conjunction with lifestyle therapy. They can also be used concurrently with weight loss medications to increase total weight loss.

Duodenal Mucosa: A New Target for the Treatment of Type 2 Diabetes

OBJECTIVE

After a high-fat and high-sugar diet, the duodenal mucosa of rodents proliferate and trigger the signal of insulin resistance, which may be the cause of type 2 diabetes (T2D). In response to this phenomenon, researchers have designed the duodenal mucosal resurfacing (DMR) procedure, mainly through the hydrothermal ablation procedure, to restore the normal mucosal surface, thereby correcting this abnormal metabolic signal. This article aims to understand the changes in duodenum before and after the onset or treatment of T2D, and the potential mechanisms of DMR procedure.

METHODS

A literature search of PubMed and Web of Science was conducted using appropriate keywords.

RESULTS

Both animal and clinical studies have shown that the villus thickness, intestinal cells, glucose transporters, enteric nerves, and gut microbiota and their metabolites in the duodenum undergo corresponding changes before and after the onset or treatment of T2D. These changes may be related to the pathogenesis of T2D. DMR procedure may produce beneficial glycemic and hepatic metabolic effects by regulating these changes.

CONCLUSION

The duodenum is an important metabolic signaling center, and limiting nutrient exposure to this critical region will have powerful metabolic benefits. The DMR procedure may regulate glycemic and hepatic parameters through various mechanisms, which needs to be further confirmed by a large number of animal and clinical studies.

Future challenges in gastroenterology and hepatology, between innovations and unmet needs: A SIGE Young Editorial Board's perspective

Gastroenterology, Digestive Endoscopy and Hepatology have faced significant improvements in terms of diagnosis and therapy in the last decades. However, many fields still remain poorly explored, and many questions unanswered. Moreover, basic-science, as well as translational and clinical discoveries, together with technology advancement will determine further steps toward a better, refined care for many gastroenterological disorders in the future. Therefore, the Young Investigators of the Italian Society of Gastroenterology (SIGE) joined together, offering a perspective on major future innovations in some hot clinical topics in Gastroenterology, Endoscopy, and Hepatology, as well as the current pitfalls and the grey zones.

Durable metabolic improvements 2 years after duodenal mucosal resurfacing (DMR) in patients with type 2 diabetes (REVITA-1 Study)

AIMS

Duodenal mucosal resurfacing (DMR) is an endoscopic procedure developed to improve metabolic parameters and restore insulin sensitivity in patients with diabetes. Here we report long-term DMR safety and efficacy from the REVITA-1 study.

MATERIALS AND METHODS

REVITA-1 was a prospective, single-arm, open-label, multicenter study of DMR feasibility, safety, and efficacy in patients with type 2 diabetes (hemoglobin A1c [HbA1c] of 7.5-10.0% (58-86 mmol/mol)) on oral medication. Safety and glycemic (HbA1c), hepatic (alanine aminotransferase [ALT]), and cardiovascular (HDL, triglyceride [TG]/HDL ratio) efficacy parameters were assessed (P values presented for LS mean change).

RESULTS

Mean ± SD HbA1c levels reduced from 8.5 ± 0.7% (69.1 ± 7.1 mmol/mol) at baseline (N = 34) to 7.5 ± 0.8% (58.9 ± 8.8 mmol/mol) at 6 months (P < 0.001); and this reduction was sustained through 24 months post-DMR (7.5 ± 1.1% [59.0 ± 12.3 mmol/mol], P < 0.001) while in greater than 50% of patients, glucose-lowering therapy was reduced or unchanged. ALT decreased from 38.1 ± 21.1 U/L at baseline to 32.5 ± 22.1 U/L at 24 months (P = 0.048). HDL and TG/HDL improved during 24-months of follow-up. No device- or procedure-related serious adverse events, unanticipated device effects, or hypoglycemic events were noted between 12 and 24 months post-DMR.

CONCLUSIONS

DMR is associated with durable improvements in insulin sensitivity and multiple downstream metabolic parameters through 24 months post-treatment in type 2 diabetes. Clinical trial reg. no. NCT02413567, clinicaltrials.gov.

Luminal Chemoreceptors and Intrinsic Nerves: Key Modulators of Digestive Motor Function

This chapter reviews data on the pathways by which luminal, mainly duodenal, chemoreceptors modulate gastro-pyloro-duodenal motor function to control emptying of nutrients into the small intestine. The vagus mediates proximal gastric relaxation caused by nutrient stimulation of duodenal/jejunal mucosal chemoreceptors. Modulation of the spatial patterning and inhibition of antral contractions during duodenal chemoreceptor activation are somewhat conflicting: both vagal control and ascending intramural nerves appear to play a role. Intraduodenal nutrients stimulate the localized pyloric contractions that prevent transpyloric flow via ascending duodenal intramural nerve pathways. Though not yet formally investigated, patterns of activation of the duodenal brake motor mechanism suggest that duodenal loop mucosal chemoreceptors signal to a brake mechanism at the most aborad region of the duodenum via descending intramural duodenal nerves.Intrinsic intramural pathways are important in the control of the first stages of digestion.

Development of Radiofrequency Ablation Generator and Balloon-Based Catheter for Microendoluminal Thin-Layer Ablation Therapy Using the Rat Duodenum as a Model of Low-Impedance Tissue

Radiofrequency ablation (RFA) is a routinely used, safe, and effective method for the tissue destruction. Often, in case of its application in malignant conditions, the extent of tissue destruction is insufficient due to the size of the target lesion, as well as due to the risk of heat-induced damage to the surrounding organs. Nevertheless, there are conditions requiring superficial precise-depth ablation with preservation of deeper layers. These are represented, for example, by mucosal resurfacing in case of Barrett's esophagus or treatment of recurrent mucosal bleeding in case of chronic radiation proctitis. Recently, new indications for intraluminal RFA use emerged, especially in the pancreatobiliary tract. In the case of intraductal use of RFA (e.g., biliary and pancreatic tract), there are currently available rigid and needle tip catheters. An expandable balloon-based RFA catheter suitable for use in such small-diameter tubular organs could be of benefit due to possible increase of contact between the probe and the target tissue; however, to prevent excessive tissue damage, a compatible generator suitable for low-impedance catheter/tissue is essential. This project aimed to develop a radiofrequency ablation generator and bipolar balloon-based catheter optimized for the application in the conditions of low-impedance tissue and (micro)endoluminal environment. Subsequent evaluation of biological effect in vivo was performed using duodenal mucosa in Wistar rat representing conditions of endoluminal radiofrequency ablation of low-impedance tissue. Experiments confirming the safety and feasibility of RFA with our prototype devices were conducted.

Bariatric and Metabolic Endoscopy: A New Paradigm

The prevalence of obesity, type 2 diabetes mellitus, and metabolic syndromes is increasing globally. Minimally invasive metabobariatric (MB) endoscopic therapies are adjunct treatments that can potentially bridge the gap between surgical interventions and medical therapy. A growing number of MB techniques are becoming available, allowing for more personalized and patient-targeted treatment options for specific disease states. MB techniques are less invasive than surgery and can precisely target different parts of the gastrointestinal tract that may be responsible for the pathophysiology of obesity and metabolic syndromes such as type 2 diabetes mellitus. These alternatives should be selected on an individualized patient basis to balance the expected clinical outcomes and desired anatomical targets with the level of invasiveness and degree of acceptable risk. Each MB intervention presents great flexibility allowing for a tailored intervention and different levels of patient engagement. Patient awareness and motivation are essential to avoid therapy withdrawal and failure. Differences between MB procedures in terms of weight loss and metabolic benefit will be discussed in this review, along with the insights on clinical decision-making processes to evaluate the potential of further evolution and growth of bariatric and metabolic endoscopy.

The Effect of Bariatric Surgery and Endoscopic Procedures on Gastroesophageal Reflux Disease

Obesity is a global epidemic posing a significant burden on patients and healthcare systems. Gastroesophageal reflux disease is associated with obesity and its prevalence is also growing worldwide. Numerous bariatric surgeries and endoscopic procedures have arisen to assist with weight loss and management of obesity-related conditions. However, the effect of these interventions on reflux is variable and the evidence is often conflicting. To date, Roux-en-Y gastric bypass remains the gold-standard for attaining both reflux and weight loss management, however novel endoscopic techniques are quickly becoming more prevalent as an alternative to surgery. This review aims to summarize currently available endoscopic and surgical weight loss procedures and their impact on reflux symptoms while emphasizing areas requiring additional investigation.

Metabolic Effects of Endoscopic Duodenal Mucosal Resurfacing: a Systematic Review and Meta-analysis

Duodenal mucosal resurfacing (DMR) is an innovative endoscopic bariatric and metabolic therapy (EBMT) emerging in recent years. It uses the duodenum to achieve better glycemic and weight control. This study aimed to evaluate in a critical and systematic way the metabolic effects of this procedure. Electronic searches were performed evaluating the DMR procedure based on predefined inclusion and exclusion criteria. Changes in measured outcomes were evaluated using random-effects models by computing weighted mean differences (MD) and corresponding 95% CIs between pre-and post-procedure metabolic characteristics. Four studies were selected for qualitative and quantitative analysis. DMR demonstrated beneficial glycemic and hepatic metabolic effects among patients with non-insulin dependent type 2 diabetes (T2D) at 3 and 6 months post-procedure.

Various Novel and Emerging Technologies in Endoscopic Bariatric and Metabolic Treatments

Obesity, along with its comorbidities, has become a significant public health concern worldwide. Bariatric surgery is considered the most effective treatment modality; however, only 2% of patients with obesity undergo bariatric surgery. Endoscopic bariatric and metabolic therapies (EBMTs) are emerging alternatives to traditional bariatric surgery for patients who are not eligible for or do not prefer surgical treatment. EBMTs are generally categorized as space-occupying, gastric restrictive, aspiration, and small bowel therapies. We aimed to review various non-balloon and non-gastroplasty devices with available clinical data and discuss the possible mechanisms of action, efficacy, and safety profile of these EMBTs.

Endobariatric procedures for obesity: clinical indications and available options

Obesity remains a growing public health epidemic that has increased healthcare costs and related comorbidities. Current treatment guidelines encourage a multidisciplinary approach starting from patient selection, interventions, and long-term follow-up to maintain weight loss. However, these conservative interventions are largely ineffective at reducing body weight due to low adherence to the treatment regimen. Recently, endoscopic bariatric therapies have become an attractive alternative to traditional invasive bariatric surgeries due to their improved efficacy, safety, and cost-effectiveness. Endoscopic bariatric therapies include intragastric balloon placement, endoscopic sleeve gastroplasty, gastric bypass revision, and aspiration therapy. These procedures fall into two separate categories depending on the primary mechanism involved: restrictive or malabsorptive. Restrictive methods, such as the Orbera® and ReShape™ intragastric balloons, increase satiation and delay gastric emptying while decreasing the amount of food that can be ingested. In contrast, malabsorptive devices, such as the EndoBarrier®, interfere with the small intestine's ability to absorb food while restoring normal gastrointestinal hormone levels regulating satiation. Together, these techniques provide useful alternatives for patients in whom pharmacological or lifestyle modifications have proven ineffective. Despite these advantages, the long-term effects of these procedures on metabolic changes remain to be studied. Furthermore, the management of complications from these procedures continues to evolve. In this review, we aim to elaborate on the clinical indications and efficacy of the endobariatric procedures, together with various types of available endoscopic bariatric therapy procedures.

Endobariatrics and Metabolic Endoscopy: Can We Solve the Obesity Epidemic with Our Scope?

PURPOSE OF REVIEW

Obesity is a chronic relapsing disease that results in cardiovascular disease, diabetes mellitus, and non-alcoholic fatty liver disease. Currently, surgery represents the most effective treatment. However, the advent of minimally invasive endoscopic bariatric therapy (EBT) has shifted the treatment paradigm to less invasive, cost-effective procedures with minimal complications and recovery time that are preferred by patients. In this review, we will describe current and future EBTs, focusing on outcomes and safety.

RECENT FINDINGS

The endoscope has provided an incisionless portal into the gastrointestinal tract for placement of space-occupying devices and intraluminal procedures. EBTs are no longer solely manipulating anatomic alterations; instead, they aim to improve metabolic parameters such as glycated hemoglobin, low-density lipoprotein, cholesterol, and hepatic indices by targeting the mucosal layer of the gastrointestinal tract. The endoscope has succeeded in facilitating clinically meaningful weight loss and improvement of metabolic parameters. Future, solutions to the obesity epidemic will likely entail genetic testing, evaluation of the microbiome, and delivery of personalized therapy, utilizing combination endoscopic modalities that change the anatomy and physiology of individual patients, with new targets such as the abnormal metabolic signal.

Dietary Protein, Fiber and Coffee Are Associated with Small Intestine Microbiome Composition and Diversity in Patients with Liver Cirrhosis

The gut microbiome is a key factor in chronic liver disease progression. In prior research, we found that the duodenal microbiome was associated with sex, ethnicity, and cirrhosis complications. Here, we examined the association between diet and the duodenal microbiome in patients with liver cirrhosis. This study included 51 participants who completed a detailed food frequency questionnaire and donated duodenal biopsies for microbiome characterization by 16S ribosomal RNA gene sequencing. Data were analyzed for alpha diversity, beta diversity, and association of taxa abundance with diet quality and components using QIIME 2 pipelines. Diet quality was assessed through calculation of the Healthy Eating Index 2010. Participants with higher adherence to protein recommendations exhibited increased microbial richness and evenness (p = 0.03) and a different microbial profile compared to those with lower adherence (p = 0.03). Prevotella-9 and Agathobacter were increased in association with increased protein adherence. Fiber consumption was also associated with the duodenal microbial profile (p = 0.01), with several taxa exhibiting significantly decreased or increased abundance in association with fiber intake. Coffee drinking was associated with microbial richness and evenness (p = 0.001), and there was a dose–response association between coffee drinking and relative abundance of Veillonella (p = 0.01). We conclude that protein, fiber, and coffee are associated with diversity and composition of the duodenal microbiome in liver cirrhosis.

Current and Future Endoscopic Weight Loss Solutions

Obesity poses a significant health care concern in the United States, with 39.8% of adults being classified as obese. Several different methods have been introduced to combat obesity, from medical therapy to surgical options. Bariatric surgery has been demonstrated to be superior to medical therapy alone for weight loss in obese patients. Despite this information, only about 1% of eligible patients undergo bariatric surgery per year. The reason for this treatment gap is multifactorial, but patient apprehension to undergo surgery is a major driving force. Many patients perceive bariatric surgery as dangerous, and believe that living with their current weight is safer than undergoing surgery. To combat this treatment gap, endoscopic therapies have been developed to reach more patients in a less invasive way. This article will review endoscopic treatment options currently available and approved by the Food and Drug Administration, as well as other treatment modalities that are currently in development.

GIP analogues and the treatment of obesity-diabetes

The potential application of glucose-dependent insulinotropic polypeptide (gastric inhibitory polypeptide, GIP) in the management of obesity and type 2 diabetes has been controversial. Initial interest in the therapeutic use of GIP was dampened by evidence that its insulinotropic activity was reduced in type 2 diabetes and by reports that it increased glucagon secretion and adipose deposition in non-diabetic individuals. Also, attention was diverted away from GIP by the successful development of glucagon-like peptide-1 (GLP-1) receptor agonists, and a therapeutic strategy for GIP became uncertain when evidence emerged that both inhibition and enhancement of GIP action could prevent or reverse obese non-insulin dependent forms of diabetes in rodents. Species differences in GIP receptor responsiveness complicated the extrapolation of evidence from rodents to humans, but initial clinical studies are investigating the effect of a GIP antagonist in non-diabetic individuals. A therapeutic role for GIP agonists was reconsidered when clinical studies noted that the insulinotropic effect of GIP was increased if near-normal glycaemia was re-established, and GIP was found to have little effect on glucagon secretion or adipose deposition in obese type 2 diabetes patients. This encouraged the development of designer peptides that act as GIP receptor agonists, including chimeric peptides that mimic the incretin partnership of GIP with GLP-1, where the two agents exert complementary and often additive effects to improve glycaemic control and facilitate weight loss. Polyagonist peptides that exert agonism at GIP, GLP-1 and glucagon receptors are also under investigation as potential treatments for obese type 2 diabetes.

Duodenal mucosal resurfacing: proof-of-concept, procedural development, and initial implementation in the clinical setting

BACKGROUND AND AIMS

We aimed to develop duodenal mucosal resurfacing (DMR), a minimally invasive upper endoscopic hydrothermal ablation procedure, to treat insulin-resistant metabolic diseases.

METHODS

We completed a sham-controlled, rodent proof-of-concept study and longitudinal safety study in pigs to demonstrate feasibility to test DMR in humans. Subsequently, the DMR procedure was implemented in an open-label first-in-human (FIH) study of safety and efficacy in patients with type 2 diabetes (T2D).

RESULTS

In rats, duodenal abrasion reduced hyperglycemia by 59 mg/dL on average, compared with no change from baseline in the sham treatment arm (P < .05). In pigs, the balloon catheter successfully and safely delivered hydrothermal ablation to the duodenal mucosa and superficial submucosa. Complete mucosal healing was demonstrated by week 6. In the FIH study, hydrothermal ablation was successfully administered with no evidence of perforation, pancreatitis, or hemorrhage. Duodenal biopsy specimens obtained 3 months postprocedure demonstrated full mucosal regrowth. No inflammation was observed, and there was minimal-to-mild collagen banding deposition observed in a proportion of ablation site biopsy specimens with no evidence of fibrotic scarring. Glycemic and hepatic measures improved through 6 months of follow-up.

CONCLUSIONS

DMR shows potential as an endoscopic intervention that improves glycemic and hepatic parameters in patients with T2D. Further mechanistic and clinical studies are underway to further explore DMR as a treatment for metabolic disease.

Endoscopic bariatric and metabolic therapies: Another tool for the management of diabetes and obesity

Endoscopic bariatric and metabolic therapies (EBMTs) have sparked significant interest as minimally invasive therapeutic options for weight loss. Although bariatric surgery remains an effective option for sustained weight loss and improvement in the metabolic syndrome, access and utilization are limited. Various EBMTs have been designed to emulate the physiologic effects of established surgical interventions, including space-occupying and non-space-occupying gastric therapies, gastric remodeling procedures, and small bowel therapies. This review discusses the safety and efficacy of available US Food and Drug Administration-approved minimally invasive endoscopic bariatric interventions, as well as those currently under investigation. In addition, the role of endoscopic revision after failed surgical intervention is discussed.

Metabolic (Bariatric and Nonbariatric) Surgery for Type 2 Diabetes: A Personal Perspective Review

: Metabolic surgery can cause amelioration, resolution, and possible cure of type 2 diabetes. Bariatric surgery is metabolic surgery. In the future, there will be metabolic surgery operations to treat type 2 diabetes that are not focused on weight loss. These procedures will rely on neurohormonal modulation related to the gut as well as outside the peritoneal cavity. Metabolic procedures are and will always be in flux as surgeons seek the safest and most effective operative modality; there is no enduring gold standard operation. Metabolic bariatric surgery for type 2 diabetes is more than part of the clinical armamentarium, it is an invitation to perform basic research and to achieve fundamental scientific knowledge.

Endoscopic Interventions in the Treatment of Obesity and Diabetes

Obesity is a global health problem which is on the rise and is strongly associated with the development of type 2 diabetes and other comorbidities. Bariatric surgery is now an established treatment for both these conditions, leading to impressive results in weight loss and glycemic control. More recently, we have seen the development of various endoscopic devices as potential alternatives or adjuncts to bariatric surgery. In this state-of-the-art review, we outline the current landscape of endoscopic treatments available for the management of both obesity and diabetes, including the clinical evidence supporting their use, efficacy, safety, and potential mechanisms of action.

Gut as an emerging organ for the treatment of diabetes: focus on mechanism of action of bariatric and endoscopic interventions

Increasing worldwide prevalence of type 2 diabetes mellitus and its accompanying pathologies such as obesity, arterial hypertension and dyslipidemia represents one of the most important challenges of current medicine. Despite intensive efforts, high percentage of patients with type 2 diabetes does not achieve treatment goals and struggle with increasing body weight and poor glucose control. While novel classes of antidiabetic medications such as incretin-based therapies and gliflozins have some favorable characteristics compared to older antidiabetics, the only therapeutic option shown to substantially modify the progression of diabetes or to achieve its remission is bariatric surgery. Its efficacy in the treatment of diabetes is well established, but the exact underlying modes of action are still only partially described. They include restriction of food amount, enhanced passage of chymus into distal part of small intestine with subsequent modification of gastrointestinal hormones and bile acids secretion, neural mechanisms, changes in gut microbiota and many other possible mechanisms underscoring the importance of the gut in the regulation of glucose metabolism. In addition to bariatric surgery, less-invasive endoscopic methods based on the principles of bariatric surgery were introduced and showed promising results. This review highlights the role of the intestine in the regulation of glucose homeostasis focusing on the mechanisms of action of bariatric and especially endoscopic methods of the treatment of diabetes. A better understanding of these mechanisms may lead to less invasive endoscopic treatments of diabetes and obesity that may complement and widen current therapeutic options.

Endoscopic Accessories Used for More Advanced Endoluminal Therapeutic Procedures

Endoscopic accessories describe an extensive variety of auxiliary instruments used for diagnostic and therapeutic endoscopy. Various endoscopic accessories have been developed over the previous few decades and are mostly used for treating neoplastic lesions, such as early gastrointestinal (GI) carcinomas and premalignant lesions. Because of extensive research on natural orifice endoluminal surgery (NOTES) in the early 2000s and recent technological developments, new devices have been developed for various advanced endoluminal therapeutic procedures. In particular, a remarkable development of endoscopic management was achieved in the field of gastroesophageal reflux disease (GERD) and obesity. In both conditions, there is treatment gap between medical and surgical therapy. A large proportion of the patients who do not respond to medical treatment and lifestyle modification, still hesitate to directly undergo surgical treatment. To bridge this gap, endoscopic management has been receiving increasing attention. In this article, I review endoscopic and/or endoluminal devices used for the treatment of GERD and obesity with proposed mechanisms of their function.