GLP-1/GIP analogues: potential impact in the landscape of obesity pharmacotherapy

Novel nutrition strategies in gastric and esophageal cancer

INTRODUCTION

Advances in treatment strategies for gastric and esophageal cancer have led to improved long-term outcomes, however the local and systemic effects of the primary tumor, neoadjuvant therapies and surgery, result in specific nutritional challenges. Comprehensive nutritional evaluation and support represents a core component of multidisciplinary holistic care for this patient population.

AREAS COVERED

We provide a detailed overview of nutritional challenges in gastric and esophageal cancer, with a focus on malignant obstruction, preoperative optimization and survivorship. We discuss current management strategies and evidence base, and describe future therapeutic targets.

EXPERT OPINION

Data to support the optimal management of malignant dysphagia and obstruction, particularly regarding patient reported outcomes, is currently lacking. The advantages of nutritional optimization in the pre- and immediate postoperative phase are well described, but further research is needed to inform optimal personalised strategies. Emerging data regarding the physiologic regulation of appetite and body weight have provided key insights and informed the development of novel therapeutic targets to improve nutritional status among patients undergoing treatment for oesophageal and gastric cancer.

Strategies to Enhance the Therapeutic Efficacy of GLP-1 Receptor Agonists through Structural Modification and Carrier Delivery

Diabetes is a metabolic disorder characterized by insufficient endogenous insulin production or impaired sensitivity to insulin. In recent years, a class of incretin-based hypoglycemic drugs, glucagon-like peptide-1 receptor agonists (GLP-1RAs), have attracted great attention in the management of type 2 diabetes mellitus (T2DM) due to their benefits, including stable glycemic control ability, a low risk of hypoglycemia, and weight reduction for patients. However, like other peptide drugs, GLP-1RAs face challenges such as instability, susceptibility to enzymatic degradation, and immunogenicity, which severely limit their clinical application. In recent years, various strategies have been developed to improve the bioavailability and therapeutic efficacy of GLP-1RAs, including structural modification and carrier-mediated delivery. This article briefly introduces the research and application status of several common GLP-1RAs and their limitations. Taking exendin-4 as an example, we focus on the research progress of improving bioavailability and therapeutic efficacy based on structural modification and carrier delivery strategies, aiming to provide reference for the development of new GLP-1RAs treatment systems.

Obesity-related Asthma: A Pathobiology-based Overview of Existing and Emerging Treatment Approaches

Although obesity-related asthma is associated with worse asthma outcomes, optimal treatment approaches for this complex phenotype are still largely unavailable. This state-of-the-art review article synthesizes evidence for existing and emerging treatment approaches for obesity-related asthma and highlights pathways that offer potential targets for novel therapeutics. Existing treatments targeting insulin resistance and obesity, including metformin and GLP-1 (glucagon-like-peptide 1) receptor agonists, have been associated with improved asthma outcomes, although GLP-1R agonist data in asthma are limited to individuals with comorbid obesity. Monoclonal antibodies approved for treatment of moderate to severe asthma generally appear to be effective in individuals with obesity, although this is based on retrospective or secondary analysis of clinical trials; moreover, although most of these asthma biologics are approved for use in the pediatric population, the impact of obesity on their efficacy has not been well studied in youth. Potential therapeutic targets being investigated include IL-6, arginine metabolites, nitro-fatty acids, and mitochondrial antioxidants, with clinical trials for each currently underway. Potential therapeutic targets include adipose tissue eosinophils and the GLP-1-arginine-advanced glycation end products axis, although data in humans are still needed. Finally, transcriptomic and epigenetic studies of "obese asthma" demonstrate enrichment of IFN-related signaling pathways, Rho-GTPase pathways, and integrins, suggesting that these too could represent future treatment targets. We advocate for further study of these potential therapeutic mechanisms and continued investigation of the distinct inflammatory pathways characteristic of obesity-related asthma, to facilitate effective treatment development for this unique asthma phenotype.

Novel enzyme-resistant pancreatic polypeptide analogs evoke pancreatic beta-cell rest, enhance islet cell turnover, and inhibit food intake in mice

Pancreatic polypeptide (PP) is a postprandial hormone secreted from pancreatic islets that activates neuropeptide Y4 receptors (NPY4Rs). PP is known to induce satiety but effects at the level of the endocrine pancreas are less well characterized. In addition, rapid metabolism of PP by dipeptidyl peptidase-4 (DPP-4) limits the investigation of the effects of the native peptide. Therefore, in the present study, five novel amino acid substituted and/or fatty acid derivatized PP analogs were synthesized, namely [P3]PP, [K13Pal]PP, [P3,K13Pal]PP, [N-Pal]PP, and [N-Pal,P3]PP, and their impact on pancreatic beta-cell function, as well as appetite regulation and glucose homeostasis investigated. All PP analogs displayed increased resistance to DPP-4 degradation. In addition, all peptides inhibited alanine-induced insulin secretion from BRIN-BD11 beta cells. Native PP and related analogs (10-8 and 10-6 M), and especially [P3]PP and [K13Pal]PP, significantly protected against cytokine-induced beta-cell apoptosis and promoted cellular proliferation, with effects dependent on the NPY4R for all peptides barring [N-Pal,P3]PP. In mice, all peptides, except [N-Pal]PP and [N-Pal,P3]PP, evoked a dose-dependent (25, 75, and 200 nmol/kg) suppression of appetite, with native PP and [P3]PP further augmenting glucagon-like peptide-1 (GLP-1) and cholecystokinin (CCK) induced reductions of food intake. The PP peptides had no obvious detrimental effect on glucose tolerance and they did not noticeably impair the glucose-regulatory actions of GLP-1 or CCK. In conclusion, Pro3 amino acid substitution of PP, either alone or together with mid-chain acylation, creates PP analogs with benefits on beta-cell rest, islet cell turnover, and energy regulation that may be applicable to the treatment of diabetes and obesity.

Changes in Food Waste among a Sample of U.S. Consumers after Beginning Anti-Obesity Medication

BACKGROUND/OBJECTIVES

Glucagon-like peptide-1 agonists (GLP1As) are increasingly prescribed to treat obesity. While studies document how these medications impact dietary habits, their relationship to consumer food waste is unexplored. Approximately one-third of all food is wasted, which creates substantial economic and environmental damage. The purpose of this study is to assess how consumers alter food waste after beginning GLP1As and to identify factors associated with this relationship.

METHODS

Retrospectively reported changes in the amount of food wasted since beginning a GLP1A are gathered from a sample of 505 U.S. consumers via a self-administered online survey. Regression analysis yields associations between changes in post-GLP1A-uptake food waste and the length and type of medication use, medication side effects, post-uptake changes in dietary habits, and respondent characteristics.

RESULTS

A total of 25% of respondents agree they waste more food since beginning the medication, while 61% disagree. Respondents are significantly less likely to agree with this statement if they have been on the medication a longer time and are significantly more likely to agree if they reported experiencing nausea since beginning the medication. Dietary changes consistent with more vegetable intake are also significantly associated with less waste.

CONCLUSIONS

Uptake of a novel class of anti-obesity medications may significantly affect food waste patterns. With the potential for widespread adoption of such medications, and given the societal import of reducing food waste, understanding the interaction of these two consumer trends is critical for projecting their joint impact on the food system and for equipping new GLP1A users to limit food waste.

NPYR modulation: Potential for the next major advance in obesity and type 2 diabetes management?

The approval of the glucagon-like peptide 1 (GLP-1) mimetics semaglutide and liraglutide for management of obesity, independent of type 2 diabetes (T2DM), has initiated a resurgence of interest in gut-hormone derived peptide therapies for the management of metabolic diseases, but side-effect profile is a concern for these medicines. However, the recent approval of tirzepatide for obesity and T2DM, a glucose-dependent insulinotropic polypeptide (GIP), GLP-1 receptor co-agonist peptide therapy, may provide a somewhat more tolerable option. Despite this, an increasing number of non-incretin alternative peptides are in development for obesity, and it stands to reason that other hormones will take to the limelight in the coming years, such as peptides from the neuropeptide Y family. This narrative review outlines the therapeutic promise of the neuropeptide Y family of peptides, comprising of the 36 amino acid polypeptides neuropeptide Y (NPY), peptide tyrosine-tyrosine (PYY) and pancreatic polypeptide (PP), as well as their derivatives. This family of peptides exerts a number of metabolically relevant effects such as appetite regulation and can influence pancreatic beta-cell survival. Although some of these actions still require full translation to the human setting, potential therapeutic application in obesity and type 2 diabetes is conceivable. However, like GLP-1 and GIP, the endogenous NPY, PYY and PP peptide forms are subject to rapid in vivo degradation and inactivation by the serine peptidase, dipeptidyl-peptidase 4 (DPP-4), and hence require structural modification to prolong circulating half-life. Numerous protective modification strategies are discussed in this regard herein, alongside related impact on biological activity profile and therapeutic promise.

Pharmacotherapy as an Augmentation to Bariatric Surgery for Obesity

A global obesity pandemic is one of the most significant health threats worldwide owing to its close association with numerous comorbidities such as type 2 diabetes mellitus, arterial hypertension, dyslipidemia, heart failure, cancer and many others. Obesity and its comorbidities lead to a higher rate of cardiovascular complications, heart failure and increased cardiovascular and overall mortality. Bariatric surgery is at present the most potent therapy for obesity, inducing a significant weight loss in the majority of patients. In the long-term, a substantial proportion of patients after bariatric surgery experience a gradual weight regain that may, in some, reach up to a presurgical body weight. As a result, anti-obesity pharmacotherapy may be needed in some patients after bariatric surgery to prevent the weight regain or to further potentiate weight loss. This article provides an overview of the use of anti-obesity medications as an augmentation to bariatric surgery for obesity. Despite relatively limited published data, it can be concluded that anti-obesity medication can serve as an effective adjunct therapy to bariatric surgery to help boost post-bariatric weight loss or prevent weight regain.

Chronic exposure to incretin metabolites GLP-1(9-36) and GIP(3-42) affect islet morphology and beta cell health in high fat fed mice

The incretin hormones, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), are rapidly degraded by dipeptidyl peptidase-4 (DPP-4) to their major circulating metabolites GLP-1(9-36) and GIP(3-42). This study investigates the possible effects of these metabolites, and the equivalent exendin molecule Ex(9-39), on pancreatic islet morphology and constituent alpha and beta cells in high-fat diet (HFD) fed mice. Male Swiss TO-mice (6-8 weeks-old) were maintained on a HFD or normal diet (ND) for 4 months and then received twice-daily subcutaneous injections of GLP-1(9-36), GIP(3-42), Ex(9-39) (25 nmol/kg bw) or saline vehicle (0.9% (w/v) NaCl) over a 60-day period. Metabolic parameters were monitored and excised pancreatic tissues were used for immunohistochemical analysis. Body weight and assessed metabolic indices were not changed by peptide administration. GLP-1(9-36) significantly (p<0.001) increased islet density per mm2 tissue, that was decreased (p<0.05) by HFD. Islet, beta and alpha cell areas were increased (p<0.01) following HFD and subsequently reduced (p<0.01-p<0.001) by GIP(3-42) and Ex(9-39) treatment. While GLP-1(9-36) did not affect islet and beta cell areas in HFD mice, it significantly (p<0.01) decreased alpha cell area. Compared to ND and HFD mice, GIP(3-42) treatment significantly (p<0.05) increased beta cell proliferation. Whilst HFD increased (p<0.001) beta cell apoptosis, this was reduced (p<0.01-p<0.001) by both GLP-1(9-36) and GIP(3-42). These data indicate that the major circulating forms of GLP-1 and GIP, namely GLP-1(9-36) and GIP(3-42) previously considered largely inactive, may directly impact pancreatic morphology, with an important protective effect on beta cell health under conditions of beta cell stress.

Investigational and emerging gastric inhibitory polypeptide (GIP) receptor-based therapies for the treatment of obesity

INTRODUCTION

One billion people live with obesity. The most promising medications for its treatment are incretin-based therapies, based on enteroendocrine peptides released in response to oral nutrients, specifically glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP). The mechanisms by which GLP-1 receptor agonism cause weight reduction are becoming increasingly understood. However, the mechanisms by which GIP receptor-modulating medications cause weight loss remain to be clarified.

AREAS COVERED

This review describes GLP-1 and GIP physiology and explores the conflicting data regarding GIP and weight management. It details examples of how to reconcile the contradictory findings that both GIP receptor agonism and antagonism cause weight reduction. Specifically, it discusses the concept of 'biased agonism' wherein exogenous peptides cause different post-receptor signaling patterns than native ligands. It discusses how GIP effects in adipose tissue and the central nervous system may cause weight reduction. It describes GIP receptor-modulating compounds and their most current trials regarding weight reduction.

EXPERT OPINION

Effects of GIP receptor-modulating compounds on different tissues have implications for both weight reduction and other cardiometabolic diseases. Further study is needed to understand the implications of GIP agonism on not just weight reduction, but also cardiovascular disease, liver disease, bone health and fat storage.

From diabetes to diverse domains: the multifaceted roles of GLP-1 receptor agonists

Glucagon-like Peptide-1 (GLP-1) receptor agonists (GLP-1RAs) emerged as a primary treatment for type-2 diabetes mellitus (T2DM), however, their multifaceted effects on various target organs beyond glycemic control opened a new era of treatment. We conducted a comprehensive literature search using databases including Scopus, Google Scholar, PubMed, and the Cochrane Library to identify clinical, in-vivo, and in-vitro studies focusing on the diverse effects of GLP-1 receptor agonists. Eligible studies were selected based on their relevance to the varied roles of GLP-1RAs in T2DM management and their impact on other physiological functions. Numerous studies have reported the efficacy of GLP-1RAs in improving outcomes in T2DM, with demonstrated benefits including glucose-dependent insulinotropic actions, modulation of insulin signaling pathways, and reductions in glycemic excursions. Additionally, GLP-1 receptors are expressed in various tissues and organs, suggesting their widespread physiological functions beyond glycemic control potentially include neuroprotective, anti-inflammatory, cardioprotective, and metabolic benefits. However, further scientific studies are still underway to maximize the benefits of GLP-1RAs and to discover additional roles in improving health benefits. This article sought to review not only the actions of GLP1RAs in the treatment of T2DM but also explore its effects on potential targets in other disorders.

Glucagon-like peptide-1 (GLP-1) receptor agonists for headache and pain disorders: a systematic review

BACKGROUND

Glucagon-like peptide-1 (GLP-1) plays a crucial role in metabolic disorders by enhancing insulin secretion, inhibiting glucagon release, and slowing gastric emptying, thereby improving glycemic control. In recent years, GLP-1 role in neuronal pathways has expanded its therapeutic potential. We aim to comprehensively evaluate the relevance of GLP-1 in headache and pain disorders.

METHODS

A systematic literature search was conducted on PubMed and Embase (Ovid) databases using the search terms "GLP-1" and "pain". Animal and human studies published in English language were included. Abstracts, reviews, and articles on other disorders than "pain" were excluded.

RESULTS

The search strategy identified 833 hits, of which 42 studies were included in the final review. The studies were categorized into four groups: inflammatory pain and osteoarthritis, headaches, neuropathic pain and diabetic neuropathy, and visceral pain and irritable bowel syndrome. GLP-1 receptor (GLP-1R) agonists, like liraglutide, have shown analgesic effects by modulating pain hypersensitivity in animal models of inflammatory and neuropathic pain. GLP-1 is involved in migraine mechanisms and GLP-1R agonists are beneficial in individuals with idiopathic intracranial hypertension. Additionally, GLP-1R agonists reduce visceral hypersensitivity and ameliorate symptoms in patients with irritable bowel syndrome.

CONCLUSIONS

The therapeutic scope of GLP-1R agonists is expanding beyond traditional metabolic targets, highlighting its potential for headache and pain disorders. Engineering bimodal molecules that integrate GLP-1R agonism with specific pain-related mechanisms may offer innovative therapeutic options.

Implications of GLP-1 Receptor Agonist on Thyroid Function: A Literature Review of Its Effects on Thyroid Volume, Risk of Cancer, Functionality and TSH Levels

The increasing utilization of Glucagon-like Peptide-1 receptor agonists (GLP-1 RAs) in managing type 2 diabetes mellitus has raised interest regarding their impact on thyroid function. In fact, while these agents are well known for their efficacy in glycemic control and weight management, their association with thyroid disorders requires clarification due to the complex interplay between thyroid hormones and metabolic pathways. Thyroid dysfunction commonly co-occurs with metabolic conditions such as diabetes and obesity, suggesting a profound interconnection between these systems. This review aims to contribute to a deeper understanding of the interaction between GLP-1 RAs and thyroid dysfunction and to clarify the safety of GLP-1 RAs in diabetic patients with thyroid disorders. By synthesizing existing evidence, this review highlights that, despite various studies exploring this topic, current evidence is inconclusive, with conflicting results. It is important to note that these drugs are relatively recent, and longer-term studies with larger sample sizes are likely needed to draw clearer conclusions. Currently, no existing guidelines provide definitive directions on this clinical issue; however, it is advisable to include thyroid function tests in the routine screening of diabetic patients, particularly those treated with GLP-1 Ras, with the goal of optimizing patient care and management.

Glucagon-based therapy for people with diabetes and obesity: What is the sweet spot?

People with obesity and type 2 diabetes have a high prevalence of metabolic-associated steatotic liver disease, hyperlipidemia and cardiovascular disease. Glucagon increases hepatic glucose production; it also decreases hepatic fat accumulation, improves lipidemia and increases energy expenditure. Pharmaceutical strategies to antagonize the glucagon receptor improve glycemic outcomes in people with diabetes and obesity, but they increase hepatic steatosis and worsen dyslipidemia. Co-agonism of the glucagon and glucagon-like peptide-1 (GLP-1) receptors has emerged as a promising strategy to improve glycemia in people with diabetes and obesity. Addition of glucagon receptor agonism enhances weight loss, reduces liver fat and ameliorates dyslipidemia. Prior to clinical use, however, further studies are needed to investigate the safety and efficacy of glucagon and GLP-1 receptor co-agonists in people with diabetes and obesity and related conditions, with specific concerns regarding a higher prevalence of gastrointestinal side effects, loss of muscle mass and increases in heart rate. Furthermore, co-agonists with differing ratios of glucagon:GLP-1 receptor activity vary in their clinical effect; the optimum balance is yet to be identified.

MicroRNA regulation of islet and enteroendocrine peptides: Physiology and therapeutic implications for type 2 diabetes

The pathogenesis of type 2 diabetes (T2D) is associated with dysregulation of glucoregulatory hormones, including both islet and enteroendocrine peptides. Microribonucleic acids (miRNAs) are short noncoding RNA sequences which post transcriptionally inhibit protein synthesis by binding to complementary messenger RNA (mRNA). Essential for normal cell activities, including proliferation and apoptosis, dysregulation of these noncoding RNA molecules have been linked to several diseases, including diabetes, where alterations in miRNA expression within pancreatic islets have been observed. This may occur as a compensatory mechanism to maintain beta-cell mass/function (e.g., downregulation of miR-7), or conversely, lead to further beta-cell demise and disease progression (e.g., upregulation of miR-187). Thus, targeting miRNAs has potential for novel diagnostic and therapeutic applications in T2D. This is reinforced by the success seen to date with miRNA-based therapeutics for other conditions currently in clinical trials. In this review, differential expression of miRNAs in human islets associated with T2D will be discussed along with further consideration of their effects on the production and secretion of islet and incretin hormones. This analysis further unravels the therapeutic potential of miRNAs and offers insights into novel strategies for T2D management.

DR10627, a Novel Dual Glucagon‑like Peptide‑1 and Gastric Inhibitory Polypeptide Receptor Agonist for the Treatment of Obesity and Type 2 Diabetes Mellitus

Introduction

Diabetes and obesity are momentous risk factors threatening people's lives and health. Currently available incretin analogue glucagon-like peptide 1 (GLP-1) possesses huge hypoglycemic effect with the unsatisfactory effect of weight loss. Co-agonists targeting GLP-1R plus glucagon receptor (GCGR) or gastric inhibitory polypeptide receptor (GIPR) show synergistic benefits in glycaemic control and weight loss. Here, we describe a novel dual GIP and GLP-1 receptor agonist, DR10627, and performed a preclinical assessment of it.

Methods

The agonistic ability of DR10627 was indirectly assessed by inducing cAMP accumulation in Chinese hamster ovary (CHO) cells transfected with GLP-1R or GIPR in vitro. The plasma pharmacokinetics of DR10627 were analysed in cynomolgus monkeys. The OGTTs were performed in Sprague‑Dawley (SD) rats. The glucose lowering effects were evaluated by repeated administration of DR10627 in diabetic (db/db) mice for 4 weeks. The effects of anti-obesity and improving metabolism of DR10627 were evaluated by repeated administration of DR10627 in diet-induced obesity (DIO) mice for 57 days.

Results

DR10627 had the capacity to activate both GLP-1R and GIPR in vitro. The terminal half-life of DR10627 was found to be approximately 4.19-5.8 h in cynomolgus monkeys. DR10627 had a great improvement in oral glucose tolerance in SD rats. Moreover, DR10627 had a potent glucose-lowering effect in db/db mice, and the hypoglycemic effect of 18 nmol/kg DR10627 was better than that of 50 nmol/kg liraglutide. In addition, 10 and 30 nmol/kg DR10627 possessed the ability of potentiating the weight-loss, lipid-lowing efficacy and improving metabolism to a greater extent than 80 nmol/kg liraglutide.

Conclusion

Preclinical assessment demonstrated that administration of DR10627 resulted in glucose lowering in SD rats and db/db mice, and substantial body weight reduction and metabolism improvement in DIO mice. DR10627 is a promising agent deserving further investigation for the treatment of type 2 diabetes and obesity.

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.

Self-Assembled Oligopeptoplex-Loaded Dissolving Microneedles for Adipocyte-Targeted Anti-Obesity Gene Therapy

Advancements in gene delivery systems are pivotal for gene-based therapeutics in oncological, inflammatory, and infectious diseases. This study delineates the design of a self-assembled oligopeptoplex (SA-OP) optimized for shRNA delivery to adipocytes, targeting obesity and associated metabolic syndromes. Conventional systems face challenges, including instability due to electrostatic interactions between genetic materials and cationic oligopeptides. Additionally, repeated injections induce discomfort and compromise patient well-being. To circumvent these issues, a dissolvable hyaluronic acid-based, self-locking microneedle (LMN) patch is developed, with improved micro-dose efficiency, for precise SA-OP delivery. This platform offers pain-free administration and improved SA-OP storage stability. In vitro studies in 3T3-L1 cells demonstrated improvements in SA-OP preservation and gene silencing efficacy. In vivo evaluation in a mice model of diet-induced type 2 diabetes yielded significant gene silencing in adipose tissue and a 21.92 ± 2.51% reduction in body weight with minimum relapse risk at 6-weeks post-treatment, representing a superior therapeutic efficacy in a truncated timeframe relative to the GLP-1 analogues currently available on the market. Additionally, SA-OP (LMN) mitigated insulin resistance, inflammation, and hepatic steatosis. These findings establish SA-OP (LMN) as a robust, minimally invasive transdermal gene delivery platform with prolonged storage stability for treating obesity and its metabolic comorbidities.

Gut-Derived Peptide Hormone Analogues and Potential Treatment of Bone Disorders in Obesity and Diabetes Mellitus

Obesity and diabetes mellitus are prevalent metabolic disorders that have a detrimental impact on overall health. In this regard, there is now a clear link between these metabolic disorders and compromised bone health. Interestingly, both obesity and diabetes lead to elevated risk of bone fracture which is independent of effects on bone mineral density (BMD). In this regard, gastrointestinal (GIT)-derived peptide hormones and their related long-acting analogues, some of which are already clinically approved for diabetes and/or obesity, also seem to possess positive effects on bone remodelling and microarchitecture to reduce bone fracture risk. Specifically, the incretin peptides, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), as well as glucagon-like peptide-2 (GLP-2), exert key direct and/or indirect benefits on bone metabolism. This review aims to provide an initial appraisal of the relationship between obesity, diabetes and bone, with a focus on the positive impact of these GIT-derived peptide hormones for bone health in obesity/diabetes. Brief discussion of related peptides such as parathyroid hormone, leptin, calcitonin and growth hormone is also included. Taken together, drugs engineered to promote GIP, GLP-1 and GLP-2 receptor signalling may have potential to offer therapeutic promise for improving bone health in obesity and diabetes.

Sustained metabolic benefits of ΔTRTX-Ac1, a tarantula venom-derived peptide, when administered together with exenatide in high-fat fed mice

AIM

The aim of the present study was to assess the long-term therapeutic efficacy of a recently discovered 28 amino acid peptide, Δ-theraphotoxin-Ac1 (Δ-TRTX-Ac1), originally isolated from venom of the Aphonopelma chalcodes tarantula. Δ-TRTX-Ac has previously been shown to improve pancreatic beta-cell function and suppress appetite.

MATERIALS AND METHODS

Δ-TRTX-Ac1 was administered twice daily in high-fat fed (HFF) mice with streptozotocin (STZ)-induced insulin deficiency, namely HFF/STZ mice, for 28 days both alone and in combination with the venom-derived glucagon-like peptide-1 (GLP-1) mimetic, exenatide.

RESULTS

Initial pharmacokinetic profiling of ΔTRTX-Ac1 revealed a plasma half-life of 2 h in mice, with ΔTRTX-Ac1 also evidenced in the pancreas 12 h post-injection. Accordingly, HFF-STZ mice received twice-daily injections of Δ-TRTX-Ac1, exenatide or a combination of both peptides for 28 days. As anticipated, HFF/STZ mice presented with hyperglycaemia, impaired glucose tolerance, decreased plasma and pancreatic insulin and disturbed pancreatic islet morphology. Administration of ΔTRTX-Ac1 reduced body weight, improved glucose tolerance and augmented pancreatic insulin content while decreasing glucagon content. Exenatide had similar benefits on body weight and pancreatic hormone content while also reducing circulating glucose. ΔTRTX-Ac1 decreased energy expenditure on day 28 whereas exenatide had no impact. All treatment regimens restored pancreatic islet and beta-cell area towards lean control levels, which was linked to significantly elevated beta-cell proliferation rates. In terms of benefits of combined ΔTRTX-Ac1 and exenatide treatment over individual agents, there was augmentation of glucose tolerance and ambulatory activity with combination therapy, and these mice presented with increased pancreatic glucagon.

CONCLUSION

These data highlight the therapeutic promise of ΔTRTX-Ac1 for diabetes, with suggestion that benefits could be enhanced through combined administration with exenatide.

Novel Dual Incretin Receptor Agonists in the Spectrum of Metabolic Diseases with a Focus on Tirzepatide: Real Game-Changers or Great Expectations? A Narrative Review

The prevalence of metabolic diseases including type 2 diabetes (T2D), obesity and non-alcoholic fatty liver disease (NAFLD) increases globally. This highlights an unmet need for identifying optimal therapies for the management of these conditions. Tirzepatide is a novel dual incretin receptor agonist (twincretin) that activates both glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptors. The aim of this narrative review was to examine the impact of novel twincretins, focusing on tirzepatide, on the management of a wide spectrum of metabolic diseases. Data from preclinical and clinical trials have shown that twincretins significantly reduce blood glucose levels in T2D, and tirzepatide is the first agent of this class that has been approved for the management of T2D. Additionally, the beneficial impact of tirzepatide on weight reduction has been corroborated in several studies, showing that this agent can achieve substantial and sustained weight loss in obese patients with or without T2D. Data also suggest that tirzepatide could be a promising drug for hepatic steatosis reduction in individuals with NAFLD. The remarkable effects of tirzepatide on glycaemic control, weight loss and liver-related outcomes have posed new research questions that are likely to lead to further advancements in the treatment of T2D, obesity and related metabolic disorders.

Peptides originally derived from Chilobrachys jingzhao tarantula venom possess beneficial effects on pancreatic beta cell health and function

Clinical approval of the glucagon-like peptide-1 (GLP-1) mimetic exenatide for the treatment of type 2 diabetes highlights the therapeutic effectiveness of venom-derived peptides. In the present study, we examined and characterised the glucose-lowering potential of synthetic Jingzhaotoxin IX and Jingzhaotoxin XI peptides, which were originally isolated from the venom of the Chinese earth tarantula Chilobrachys jingzhao. Following confirmation of lack of beta-cell toxicity of synthetic peptides, assessment of enzymatic stability and effects on in vitro beta-cell function were studied, alongside putative mechanisms. Glucose homeostatic and appetite suppressive actions of Jingzhaotoxin IX and Jingzhaotoxin XI alone, or in combination with exenatide, were then assessed in normal overnight fasted C57BL/6 mice. Synthetic Jingzhaotoxin peptides were non-toxic and exhibited a decrease in mass of 6 Da in Krebs-Ringer bicarbonate buffer suggesting inhibitor cysteine knot (ICK)-like formation, but interestingly were liable to plasma enzyme degradation. The Jingzhaotoxin peptides evoked prominent insulin secretion from BRIN BD11 beta-cells, with activity somewhat characteristic of Kv2.1 channel binding. In addition, Jingzhaotoxin peptides enhanced beta-cell proliferation and provided significant protection against cytokine-induced apoptosis. When injected co-jointly with glucose, the Jingzhaotoxin peptides slightly decreased blood-glucose levels but had no effect on appetite in overnight fasted mice. Whilst the Jingzhaotoxin peptides did not enhance exenatide-induced benefits on glucose homeostasis, they augmented exenatide-mediated suppression of appetite. Taken together, these data highlight the therapeutic potential of tarantula venom-derived peptides, such as Jingzhaotoxin IX and Jingzhaotoxin XI either alone or in combination with exenatide, for diabetes and related obesity.