Glucagon-like peptide-1 receptor co-agonists for treating metabolic disease

Design of potent and proteolytically stable double biaryl-stapled GLP-1R/GIPR peptide dual agonists

The successful treatment of type 2 diabetes and obesity with tirzepatide highlights the dual agonists of glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic peptide receptor (GIPR) as a powerful new generation of anti-diabetic drugs. However, tirzepatide and other GLP-1R/GIPR dual agonists currently in clinical development are linear peptides susceptible to proteolytic cleavage, thus preventing their uses as oral drugs. Previously, we reported the design of the proteolytically stable GLP-1R/GIPR peptide dual agonists via sidechain biaryl stapling. Although the stapled peptides exhibit improved proteolytic stability, they are still not sufficiently stable for oral delivery. Here, we report on the design and synthesis of more stable GLP-1R/GIPR dual agonists through a combined use of double biaryl stapling and α-methylation. One of the double-stapled and α-methylated peptides, DA23-Bpy10,17Bpy21,28, showed more potent and balanced dual agonist activities than tirzepatide, a half-life of 30 min in simulated intestinal fluid, and equal glucose lowering activity compared to semaglutide in oral glucose tolerance test in rodents. These potent and proteolytically stable double biaryl-stapled analogs should provide valuable lead peptides for developing oral GLP-1R/GIPR dual agonist drugs to treat diabetes and obesity.

Nicotinic acid increases adipose tissue dietary fatty acid trapping and reduces postprandial hepatic and cardiac fatty acid uptake in prediabetes

Increased adipose tissue (AT) dietary fatty acids (DFA) trapping limits fatty acid exposure to lean organs in the face of elevated postprandial nonesterified fatty acid (NEFA) flux from excess AT intracellular lipolysis in prediabetes. We hypothesized that pharmacological inhibition of postprandial AT intracellular lipolysis using short-acting nicotinic acid (NA) would increase AT DFA trapping and limit AT NEFA spillover to lean organs in subjects with prediabetes. Twenty subjects with impaired glucose tolerance and 19 individuals with normal glucose tolerance underwent four postprandial studies with positron emission tomography/computed tomography with radio-labeled fatty acid tracers and stable isotopic palmitate tracers. Over the 6-h postprandial period, NA increased AT DFA partitioning with reciprocal reduction in liver and in muscle. NA also robustly reduced cardiac and liver total (DFA + NEFA) postprandial fatty acid uptake. Short-acting NA administered postprandially thus enhances AT DFA trapping and markedly reduces postprandial hepatic and cardiac fatty acid uptake. (clinicaltrials.gov NCT02808182).

Effects of Tirzepatide in Type 2 Diabetes: Individual Variation and Relationship to Cardiometabolic Outcomes

BACKGROUND

Tirzepatide-a dual GIP/GLP-1 receptor agonist-exerts pleiotropic effects on cardiometabolic health.

OBJECTIVES

The authors sought to investigate the efficacy of tirzepatide in improving different cardiometabolic risk factors across individuals and subpopulations.

METHODS

Using an independent, global data-sharing and analytics platform, we performed an individual participant data meta-analysis by pooling data from 7 Phase 3 randomized clinical trials that compared tirzepatide with placebo or standard antihyperglycemic agents in individuals with type 2 diabetes. The study outcomes were the presence of a range of cardiometabolic abnormalities, representing components of metabolic syndrome (MetS) (elevated waist circumference, triglycerides, blood pressure, and fasting blood glucose, and decreased high-density lipoprotein cholesterol), as well as elevated body mass index and MetS (≥3 cardiometabolic abnormalities). Outcomes were modeled using mixed-effects models, with inverse probability weighting to account for study design differences.

RESULTS

We included 7,805 participants with a weighted median age of 59 years (Q1-Q3: 51-66 years) and 43.2% women. Over a weighted median treatment duration of 41.0 weeks, tirzepatide reduced the odds of all cardiometabolic abnormalities, ranging from 34% reduction for the odds of decreased high-density lipoprotein cholesterol (OR: 0.66 [95% CI: 0.52-0.84]) to 96% reduction in the odds of elevated body mass index (OR: 0.04 [95% CI:0.02-0.08]), and 72% reduction for the odds of MetS (OR: 0.28 [95% CI: 0.24-0.33]). Tirzepatide's superior efficacy in resolving MetS was consistent across demographic and clinical subpopulations, with higher efficacy in age <65 years vs ≥65 years, and in individuals without vs with baseline use of sodium-glucose cotransporter 2 inhibitors (P for interaction = 0.008 and 0.009, respectively).

CONCLUSIONS

This pooled analysis suggests that tirzepatide may improve cardiometabolic abnormalities and resolve MetS in individuals with type 2 diabetes.

The NLRP3 inhibitor NT-0796 enhances and sustains GLP-1R agonist-mediated weight loss in a murine diet-induced obesity model

OBJECTIVE

In order to investigate whether a central nervous system penetrant anti-inflammatory could augment or sustain obesity treatment with semaglutide (Wegovy), a glucagon-like peptide-1 receptor (GLP-1R) agonist, we tested two hypotheses in models of diet-induced obesity (DIO): 1) a centrally penetrant NLPR3 inhibitor, NT-0796, drives enhanced weight loss when combined with low-dose semaglutide, compared to monotherapy; and 2) NT-0796 monotherapy sustains weight loss induced by semaglutide.

METHODS

Mice fed a standard high-fat or a polyunsaturated fatty acid diet served as models of DIO and were dosed with low-dose semaglutide, NT-0796, or combinations. Body weight, food intake, peripheral inflammatory markers, and hypothalamic glial fibrillary acidic protein expression were assessed.

RESULTS

Combined dosing of NT-0796 with semaglutide drove greater weight loss than either monotherapy alone, and this effect was enhanced in mice consuming the polyunsaturated fatty acid diet. In addition, NT-0796 sharply limited weight regain following cessation of semaglutide therapy and normalized markers of both peripheral inflammation and hypothalamic astrogliosis to a far greater extent than either semaglutide or calorie restriction.

CONCLUSIONS

Alleviation of obesity-associated inflammation via NLRP3 inhibition 1) constitutes an effective weight-loss strategy as monotherapy in mice with DIO, 2) augments the weight-loss efficacy of a subtherapeutic dose of semaglutide, and 3) blocks recovery of lost weight following cessation of semaglutide.

GLP-1-based therapies for diabetes, obesity and beyond

Glucagon-like peptide 1 (GLP-1)-based therapies, such as semaglutide and tirzepatide, represent highly effective treatment options for people with type 2 diabetes and obesity, enabling effective control of glucose and weight loss, while reducing cardiovascular and renal morbidity and mortality. The success of these medicines has spurred development of next-generation GLP-1-based drugs, promising greater weight loss, improved tolerability and additional options for the route and frequency of dosing. This Review profiles established and emerging GLP-1-based medicines, discussing optimization of pharmacokinetics and tolerability, engagement of new therapeutically useful pathways and safety aspects. Structurally unique GLP-1-based medicines that achieve substantially greater and rapid weight loss may impact musculoskeletal health, providing a rationale for therapeutics that more selectively target adipose tissue loss while preserving muscle mass and strength. Ongoing clinical trials in peripheral vascular disease, neuropsychiatric and substance use disorders, metabolic liver disease, arthritis, hypertension and neurodegenerative disorders may broaden indications for GLP-1-based therapeutics.

MASLD: Prevalence, Mechanisms, and Sex-Based Therapies in Postmenopausal Women

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease influenced by genetic, lifestyle, and environmental factors. While MASLD is more prevalent in men, women are at increased risk after menopause, highlighting the critical pathogenetic role of sex hormones. The complex interplay between estrogen deficiency, visceral fat accumulation, metabolic syndrome (MetS), and inflammation accelerates disease progression, increases cardiovascular (CV) risk, and triggers a cycle of worsening adiposity, metabolic dysfunction, and psychological problems, including eating disorders. Weight loss in postmenopausal women can significantly improve both metabolic and psychological outcomes, helping to prevent MASLD and related conditions. This review examines the prevalence of MASLD, its comorbidities (type 2 diabetes T2D, CV, mental disorders), pathogenetic mechanisms, and pharmacological treatment with GLP-1 receptor agonists (GLP1-RAs), with a focus on postmenopausal women. Given the use of GLP1-RAs in the treatment of obesity and T2D in MASLD patients, and the increase in MetS and MASLD after menopause, this review analyzes the potential of a stable GLP-1-estrogen conjugate as a therapeutic approach in this subgroup. By combining the synergistic effects of both hormones, this dual agonist has been shown to increase food intake and food reward suppression, resulting in greater weight loss and improved insulin sensitivity, glucose, and lipid metabolism. Therefore, we hypothesize that this pharmacotherapy may provide more targeted therapeutic benefits than either hormone alone by protecting the liver, β-cells, and overall metabolic health. As these effects are only supported by preclinical data, this review highlights the critical need for future research to evaluate and confirm the mechanisms and efficacy in clinical settings, particularly in postmenopausal women.

Dose-related effects of intraduodenal quinine on plasma glucose, glucoregulatory hormones and gastric emptying of a nutrient drink, and energy intake, in men with type 2 diabetes: a double-blind, randomised, crossover study

AIMS/HYPOTHESIS

Quinine, when administered intraduodenally to activate bitter-taste receptors, in a dose of 600 mg, stimulates glucagon-like peptide-1 (GLP-1) and insulin, slows gastric emptying and lowers postprandial glucose in healthy people, with consequent implications for the management of type 2 diabetes; the effect of quinine on energy intake is uncertain. We have investigated the dose-related effects of quinine on postprandial blood glucose levels and energy intake in people with type 2 diabetes.

METHODS

Male participants with type 2 diabetes (age: 68±5 years; HbA1c: 49.0±5.0 mmol/mol [6.7±0.4%], BMI: 30±1 kg/m2) received in two study parts (A and B, n=12 each), on three separate occasions each, in randomised, crossover fashion, control, or 300 mg (QHCl-300) or 600 mg (QHCl-600) quinine hydrochloride, intraduodenally 30 min before a nutrient drink (2092 kJ, 74 g carbohydrate) (part A) or a standardised buffet-lunch (part B). Both the participants and investigators performing the study procedures were blinded to the treatments. In part A, plasma glucose, GLP-1, C-peptide and glucagon were measured at baseline, for 30 min after quinine alone and for 3 h post drink. Gastric emptying of the drink was measured with a 13C-acetate breath test. In part B, energy intake from the buffet-lunch was quantified.

RESULTS

Quinine alone had no effect. Post drink, both quinine doses reduced peak plasma glucose markedly (QHCl-600 by 2.8±0.6 mmol/l) and slowed gastric emptying (all p<0.05; n=12, except for gastric emptying, n=11). QHCl-600, but not QHCl-300, stimulated plasma GLP-1 and C-peptide modestly (both p<0.05). Quinine did not affect energy intake.

CONCLUSIONS/INTERPRETATION

In type 2 diabetes, acute intraduodenal administration of quinine markedly reduces the plasma glucose response to oral carbohydrate, but does not affect energy intake. These findings support the potential use of quinine to reduce postprandial blood glucose levels in type 2 diabetes.

TRIAL REGISTRATION

anzctr.org.au ACTRN12620000972921/ACTRN12621000218897 FUNDING: The study was funded by a Diabetes Australia Research Project Grant.

Incretin-based therapies: advancements, challenges, and future directions in type 2 diabetes management

Incretin-based medicines have considerably impacted the treatment of type 2 diabetes mellitus (T2DM), providing considerable advantages in glycemic regulation, weight control, and cardiovascular results. This narrative review examines progress in incretin medicines, encompassing glucagon-like peptide-1 (GLP-1) receptor agonists, dual-receptor, and triple-receptor agonists, while emphasizing their therapeutic advantages, obstacles, and prospective developments. The examined articles were sourced from databases including PubMed and Google Scholar, concentrating on publications predominantly from 2010 to 2024. Selective foundational papers released before this timeline were incorporated to furnish critical historical context about incretin processes and their discovery. Incretin-based medicines, despite their therapeutic efficacy, encounter hurdles including elevated treatment costs, patient compliance difficulties, and variability in response attributable to genetic and physiological variables. Moreover, there are still deficiencies in comprehending the long-term cardiovascular safety and cancer risks linked to these medicines. Emerging dual- and triple-receptor agonists demonstrate potential in overcoming the shortcomings of conventional GLP-1 receptor agonists, providing enhanced metabolic results and broader uses in intricate disease profiles. Future research must concentrate on economic obstacles, streamlined regimens, customized medicine, the integration of artificial intelligence, patient stratification, as well as the safety and efficacy of incretin-based medicines for holistic management of T2DM.

What is the pipeline for future medications for obesity?

Obesity is a chronic disease associated with increased risk of obesity-related complications and mortality. Our better understanding of the weight regulation mechanisms and the role of gut-brain axis on appetite has led to the development of safe and effective entero-pancreatic hormone-based treatments for obesity such as glucagon-like peptide-1 (GLP-1) receptor agonists (RA). Semaglutide 2.4 mg once weekly, a subcutaneously administered GLP-1 RA approved for obesity treatment in 2021, results in 15-17% mean weight loss (WL) with evidence of cardioprotection. Oral GLP-1 RA are also under development and early data shows similar WL efficacy to semaglutide 2.4 mg. Looking to the next generation of obesity treatments, combinations of GLP-1 with other entero-pancreatic hormones with complementary actions and/or synergistic potential (such as glucose-dependent insulinotropic polypeptide (GIP), glucagon, and amylin) are under investigation to enhance the WL and cardiometabolic benefits of GLP-1 RA. Tirzepatide, a dual GLP-1/GIP receptor agonist has been approved for glycaemic control in type 2 diabetes as well as for obesity management leading in up to 22.5% WL in phase 3 obesity trials. Other combinations of entero-pancreatic hormones including cagrisema (GLP-1/amylin RA) and the triple agonist retatrutide (GLP-1/GIP/glucagon RA) have also progressed to phase 3 trials as obesity treatments and early data suggests that may lead to even greater WL than tirzepatide. Additionally, agents with different mechanisms of action to entero-pancreatic hormones (e.g. bimagrumab) may improve the body composition during WL and are in early phase clinical trials. We are in a new era for obesity pharmacotherapy where combinations of entero-pancreatic hormones approach the WL achieved with bariatric surgery. In this review, we present the efficacy and safety data for the pipeline of obesity pharmacotherapies with a focus on entero-pancreatic hormone-based treatments and we consider the clinical implications and challenges that the new era in obesity management may bring.

Comparative efficacy and safety of GLP-1 receptor agonists for weight reduction: A model-based meta-analysis of placebo-controlled trials

Aim

Obesity is a global epidemic. The FDA has approved glucagon-like peptide-1 (GLP-1) receptor agonists such as Liraglutide, Semaglutide, and the GLP-1/gastric inhibitory polypeptide (GIP) dual agonist Tirzepatide for the treatment of obesity. Clinical trials of GLP-1/GIP/glucagon(GCG) triple agonists are ongoing. This study compared the efficacy and safety profiles of different GLP-1 receptor agonists (GLP-1RAs) for weight reduction and explored the related influencing factors, providing quantitative information for the development of GLP-1RAs and their clinical use.

Methods

This systematic review of public databases included placebo-controlled randomized clinical trials of GLP-1RAs. Time-course, dose-response, and covariate models were used to describe the efficacy characteristics and influencing factors of different GLP-1RAs. Subgroup analyses were performed to explore efficacy differences in receptor specificity. Meta-analyses compared the incidence of adverse event and dropout rates among different GLP-1RAs.

Results

Fifty-five studies involving 16,269 participants and 12 GLP-1RAs were included. Six drugs showed significant dose-response relationships. The maximum weight reduction effect ranged from 4.25 kg (Liraglutide) to 22.6 kg (Retatrutide). Reported onset times ranged from 6.4 weeks (Orforglipron) to 19.5 weeks (Tirzepatide). At 52 weeks, weight reduction effects were 7.03 kg, 11.07 kg, and 24.15 kg for mono-agonists, dual-agonists, and tri-agonists, respectively. There was a significant negative correlation in the exponential pattern between age and weight reduction effect, whereas baseline weight and BMI had no significant impact. Common adverse events of GLP-1RAs, reported in the literature include nausea, vomiting, diarrhea, and constipation, with a significantly higher incidence of nausea than that of placebo.

Conclusions

This study provides a quantitative evaluation of the efficacy and safety of GLP-1RAs and offers valuable insights into the assessment of new drugs for weight reduction.

An oral liraglutide nanomicelle formulation conferring reduced insulin-resistance and long-term hypoglycemic and lipid metabolic benefits

Type 2 diabetes is a chronic disease characterized by insulin resistance and often worsened by obesity. Effective management involves the use of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) to assist with glycemic control and weight management. However, these drugs must be administered subcutaneously due to their low oral bioavailability. We developed an oral liraglutide (LRG) formulation by electrostatic complexation of GLP-1 RA with bile acid derivatives and nanomicelle (NM) formation, with non-ionic surfactant n-dodecyl-β-d-maltoside (DDM). The optimized formulation, LDD[1:2:4]-NM, had a mean particle size of 75.9 ± 5.60 nm and a permeability 1347 % higher than that of unformulated LRG when tested in Caco-2/HT29-MTX-E12 cell monolayers. In rats, oral bioavailability was 4.63-fold higher than that of unformulated LRG (1.11 ± 0.20 % vs. 5.14 ± 0.63 %). The absorption mechanism included clathrin-mediated endocytosis, macropinocytosis, and an ASBT-mediated pathway. A 12-week oral treatment consisting of a daily dose of 20 mg LDD[1:2:4]-NM/kg significantly reduced glycohemoglobin levels, a marker of diabetic control, and the HOMA-IR index, a marker of insulin resistance. The weight of epididymal and inguinal white adipose tissue and brown adipose tissue (BAT) was also reduced. Moreover, LDD[1:2:4]-NM had a greater impact on BAT activation, pro-inflammatory gene expression, and lipid metabolism than subcutaneous LRG. This study showed that an oral NM formulation can efficiently deliver LRG. Long-term treatment led to improved hyperglycemic effects, insulin resistance, and modulated lipid metabolism. LDD[1:2:4]-NM is thus a promising oral therapeutic option for the management of type 2 diabetes, potentially transforming treatment paradigms based on the availability of a more convenient administration route.

Tirzepatide alleviates oxidative stress and inflammation in diabetic nephropathy via IL-17 signaling pathway

Oxidative stress (OS) and inflammation play essential roles in the development of diabetic nephropathy (DN). Tirzepatide (TZP) has a protective effect in diabetes. However, its underlying mechanism in DN remains unclear. DN model mice were induced by intraperitoneal injection of streptozotocin (STZ; 60 mg/kg), followed by administration of different doses of TZP (3 and 10 nmol/kg) via intraperitoneal injection for 8 weeks. The effects of TZP on DN were evaluated by detecting DN-related biochemical indicators, kidney histopathology, apoptosis, OS, and inflammation levels. Additionally, to further reveal the potential mechanism, we investigated the role of TZP in modulating the IL-17 pathway. TZP reduced serum creatinine (sCR), blood urea nitrogen (BUN), and advanced glycosylation end products (AGEs) levels, while simultaneously promoting insulin secretion in diabetic mice. Additionally, TZP attenuated tubular and glomerular injury and reduced renal apoptosis levels. Further studies found that TZP increased the levels of SOD and CAT, and decreased MDA. Meanwhile, TZP also reduced the expression of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) in both mouse serum and kidney homogenates. TZP effectively inhibited the IL-17 pathway, and subsequent intervention with an IL-17 pathway agonist (IL-17A) reversed the suppressive effects of TZP on OS and inflammation. TZP can improve DN by inhibiting OS and inflammation through the suppression of the IL-17 pathway.

Glucagon-like peptide-1 receptor agonists in peri-operative care: Dispelling myths and unveiling insights with essential considerations for anaesthesiologists

With the growing use of glucagon-like-peptide-1 (GLP-1) receptor (GLP-1R) agonists as anti-obesity medication it is becoming increasingly important to examine its consequences in the peri-operative period. GLP-1R agonists are known for their effects of glucose-lowering and gastroparesis the latter causing some safety concerns regarding induction of anaesthesia, more specifically the risk of pulmonary aspiration. This article gathers the available evidence on this subject in addition to the already established guidelines. Current evidence makes us assume there is indeed an increased level of gastroparesis, but there are no studies to date with evidential confirmation of a presumed elevated risk of pulmonary aspiration. Future perspectives should focus on the actual risk of pulmonary aspiration and the possible implementation of ultrasound in the preoperative assessment.

Exploring the therapeutic potential of glucagon-like peptide 1 agonists in metabolic disorders

This article comments on the work by Soresi and Giannitrapani. The authors have stated that one of the most novel and promising treatments for metabolic dysfunction-associated steatotic liver disease (MASLD) is the use of glucagon-like peptide 1 receptor agonists, especially when used in combination therapy. However, despite their notable efficacy, these drugs were not initially designed to target MASLD directly. In a groundbreaking development, the Food and Drug Administration has recently approved resmetirom, the first treatment specifically aimed at reducing liver fibrosis in metabolic-associated steatohepatitis. Resmetirom, an orally administered, liver-directed thyroid hormone beta-selective agonist, acts directly on intrahepatic pathways, enhancing its therapeutic potential and marking the beginning of a new era in the treatment of MASLD. Furthermore, the integration of lifestyle modifications into liver disease management is an essential component that should be considered and reinforced. By incorporating dietary changes and regular physical exercise into treatment, patients may achieve improved outcomes, reducing the need for pharmacological interventions and/or improving treatment efficacy. As a complement to medical therapies, lifestyle factors should not be overlooked in the broader strategy for managing MASLD.

GLP-1/GIP dual agonist tirzepatide normalizes diabetic nephropathy via PI3K/AKT mediated suppression of oxidative stress

BACKGROUND

Effective therapeutic approaches for the treatment of diabetic nephropathy (DN) with irreversible deterioration of renal function are currently lacking. In this study, we aimed to investigate the ability of the glucagon-likepeptide-1 (GLP-1)/ gastric inhibitory polypeptide (GIP) dual agonist, tirzepatide to alleviate DN in mice and its underlying mechanisms.

METHODS

We investigated the reno-protective effect of semaglutide and tirzepatide in a mouse model of DN, an insulin-treated positive control group was also included. Indicators of diabetic kidney injury and oxidative stress biomarkers were also assessed. RNA-seq analysis of renal tissue was conducted to explore the potential mechanism of action of tirzepatide and in vitro cell experiments were performed to validate its pathway.

RESULTS

In DN mice, one-third the dose of tirzepatide was consistent with that of semaglutide in lowering glucose, body weight, and urine albumin-to-creatine ratio (UACR) and in improving antioxidative stress activities, while insulin treatment could not effectively restore the UACR. RNA-seq analysis revealed that the PI3K-AKT signaling pathway was significantly enriched after tirzepatide treatment compared with that in the DN model. Confirmatory experiments demonstrated that tirzepatide regulated oxidative stress and the PI3K-AKT pathway in mouse podocyte cell-5 cells exposed to high glucose. Further mechanistic validation suggested that the antioxidative activity of tirzepatide was reversed by PI3K inhibitor.

CONCLUSION

These findings expand the potential effects and mechanics of tirzepatide in the treatment of DN, which may provide a novel therapeutic approach and therapeutic target for DN treatment.

Bile acids and incretins as modulators of obesity-associated atherosclerosis

Obesity is one of the major global health concerns of the 21st century, associated with many comorbidities such as type 2 diabetes mellitus (T2DM), metabolic dysfunction-associated steatotic liver disease, and early and aggressive atherosclerotic cardiovascular disease, which is the leading cause of death worldwide. Bile acids (BAs) and incretins are gut hormones involved in digestion and absorption of fatty acids, and insulin secretion, respectively. In recent years BAs and incretins are increasingly recognized as key signaling molecules, which target multiple tissues and organs, beyond the gastro-intestinal system. Moreover, incretin-based therapy has revolutionized the treatment of T2DM and obesity. This mini review highlights the current knowledge about dysregulations in BA homeostasis in obesity with a special focus on atherosclerosis as well as athero-modulating roles of incretins and currently available incretin-based therapies.

A randomized phase I study of BI 1820237, a novel neuropeptide Y receptor type 2 agonist, alone or in combination with low-dose liraglutide in otherwise healthy men with overweight or obesity

AIMS

Pharmacotherapeutic options for obesity treatment include glucagon-like peptide-1 receptor (GLP-1R) agonists, for example, liraglutide. However, an unmet need remains, particularly in patients with a high body mass index (BMI), as GLP-1R agonists are associated with gastrointestinal adverse events (AEs) and some patients do not respond to treatment. Neuropeptide Y (NPY) and peptide YY bind G-protein-coupled Y receptors and represent attractive targets for modulating bodyweight.

MATERIALS AND METHODS

This first-in-human, three-part, partially blinded phase I study (NCT04903509) investigated the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of single ascending doses of the peptidic NPY2R agonist BI 1820237, with/without low-dose liraglutide: part 1 (participants randomized to receive BI 1820237: 0.075-2.4 mg or placebo), part 2 (BI 1820237: 1.2 mg or placebo) and part 3 (BI 1820237: 0.025-1.2 mg + liraglutide 0.6 mg or placebo + liraglutide 0.6 mg). Primary endpoint is the proportion of participants with drug-related AEs. Secondary endpoints are tolerability, PK and PD.

RESULTS

In total, 95 otherwise healthy men with increased BMI (25.0-34.9 kg/m2) were randomized. Drug-related AEs, mainly gastrointestinal events, were reported by 39.0% of participants (n = 23) in parts 1 + 2 and 30.6% of participants (n = 11) in part 3; one drug-related AE (11.1%, part 3) was reported in a participant receiving placebo with liraglutide. Post-dose paracetamol PK suggested that BI 1820237 and low-dose liraglutide exhibited additive effects on gastric emptying.

CONCLUSIONS

BI 1820237 treatment was associated with transient nausea and vomiting at higher doses. No differences in tolerability were observed when combined with liraglutide; effects on gastric emptying appeared additive.

Incretin-based therapies for the management of cardiometabolic disease in the clinic: Past, present, and future

Among newer classes of drugs for type 2 diabetes mellitus (T2DM), glucagon-like peptide 1 receptor agonists (GLP-1 RAs) are incretin-based agents that lower both blood sugar levels and promote weight loss. They do so by activating pancreatic GLP-1 receptors (GLP-1R) to promote glucose-dependent insulin release and inhibit glucagon secretion. They also act on receptors in the brain and gastrointestinal tract to suppress appetite, slow gastric emptying, and delay glucose absorption. Phase 3 clinical trials have shown that GLP-1 RAs improve cardiovascular outcomes in the setting of T2DM or overweight/obesity in people who have, or are at high risk of having atherosclerotic cardiovascular disease. This is largely driven by reductions in ischemic events, although emerging evidence also supports benefits in other cardiovascular conditions, such as heart failure with preserved ejection fraction. The success of GLP-1 RAs has also seen the evolution of other incretin therapies. Tirzepatide has emerged as a dual glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 RA, with more striking effects on glycemic control and weight reduction than those achieved by isolated GLP-1R agonism alone. This consists of lowering glycated hemoglobin levels by more than 2% and weight loss exceeding 15% from baseline. Here, we review the pharmacological properties of GLP-1 RAs and tirzepatide and discuss their clinical effectiveness for T2DM and overweight/obesity, including their ability to reduce adverse cardiovascular outcomes. We also delve into the mechanistic basis for these cardioprotective effects and consider the next steps in implementing existing and future incretin-based therapies for the broader management of cardiometabolic disease.

The power of three: Retatrutide's role in modern obesity and diabetes therapy

The increasing prevalence of obesity and type 2 diabetes mellitus has resulted in a significant challenge to public health throughout the globe. It required the development of novel therapeutic approaches. Retatrutide is a groundbreaking triple agonist that targets glucagon receptors, gastric inhibitory polypeptide, and glucagon-like peptide-1. Retatrutide's complex mechanism of action involves a synergistic interaction among these receptors, resulting in increased insulin secretion, improved glucose homeostasis, and refined appetite modulation. Clinical trials in phases 1 to 3 have demonstrated significant efficacy, highlighted by significant reductions in body weight and favorable glycemic control outcomes. Additionally, retatrutide shows promise in mitigating cardiovascular risk factors and addressing metabolic dysfunction-associated steatotic liver disease. However, careful attention is required to delineate its long-term safety profile, explore its potential in special populations, unravel its adjunctive therapeutic roles, and elucidate its mechanisms in pediatric cohorts. As a transformative therapeutic modality, retatrutide represents a beacon of hope, signifying transformative changes in the management landscape of obesity and type 2 diabetes mellitus (T2DM), and warranting continued exploration and refinement in clinical practice. This narrative review examines the therapeutic potential of retatrutide in the management of obesity and T2DM.

Glp1r-Lepr coexpressing neurons modulate the suppression of food intake and body weight by a GLP-1/leptin dual agonist

Glucagon-like peptide-1 (GLP-1) and leptin signal recent feeding and long-term energy stores, respectively, and play complementary roles in the modulation of energy balance. Previous work using single-cell techniques in mice revealed the existence of a population of leptin receptor (Lepr)-containing dorsomedial hypothalamus (DMH) neurons marked by the expression of GLP-1 receptor (Glp1r; LepRGlp1r neurons) that play important roles in the control of feeding and body weight by leptin. Here, we demonstrate the existence of a population of LepRGlp1r neurons in the DMHs of nonhuman primates (NHPs), suggesting the potential translational relevance of these neurons. Consequently, we developed a GLP-1R/LepR dual agonist and demonstrated the physiological activity of both components in vivo using leptin-deficient and Lepr-deficient murine models. We further found roles for LepRGlp1r neurons in mediating the dual agonist's efficacy on food intake and body weight loss. Ablating Lepr in Glp1r-expressing neurons (LeprGlp1rKO mice) abrogated the suppression of food intake by the dual agonist. Furthermore, reactivation of Glp1r expression in Lepr neurons on an otherwise Glp1r-null background (Glp1rLeprRe mice) was sufficient to permit the suppression of food intake and body weight by the dual agonist. Hence, LepRGlp1r neurons represent targets for a GLP-1R/LepR dual agonist that potently reduces food intake and body weight.

GLP-1 receptor agonists in patients with chronic kidney disease and either overweight or obesity

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have emerged as game-changers across the cardiovascular-kidney-metabolic (CKM) spectrum: overweight/obesity, type 2 diabetes mellitus (T2DM) and associated chronic kidney disease (CKD) and cardiovascular disease (CVD). Liraglutide, semaglutide and tirzepatide are European Medicines Agency approved to improve metabolic control in T2DM and to decrease weight in persons with obesity [body mass index (BMI) ≥30 kg/m2] or with overweight (BMI ≥27 kg/m2) associated with weight-related comorbidities such as hypertension, dyslipidaemia, CVD and others. Additionally, liraglutide and semaglutide are approved to reduce CVD risk in patients with CVD and T2DM. Semaglutide is also approved to reduce CVD risk in patients with CVD and either obesity or overweight and in phase 3 clinical trials showed kidney and cardiovascular protection in patients with T2DM and albuminuric CKD (FLOW trial) as well as in persons without diabetes that had CVD and overweight/obesity (SELECT trial). Thus, nephrologists should consider prescribing GLP-1 RAs to improve metabolic control, reduce CVD risk or improve kidney outcomes in three scenarios: patients with overweight and a related comorbid condition such as hypertension, dyslipidaemia or CVD, patients with obesity and patients with T2DM. This review addresses the promising landscape of GLP-1 RAs to treat persons with overweight or obesity, with or without T2DM, within the context of CKD, assessing their safety and impact on weight, metabolic control, blood pressure and kidney and cardiovascular outcomes, as part of a holistic patient-centred approach to preserve CKM health.

Effect of tirzepatide on the progression of coronary atherosclerosis using MDCT: Rationale and design of the tirzepatide treatment on coronary atherosclerosis progression: The (T-Plaque) randomized-controlled trial design

INTRODUCTION

Tirzepatide is a novel once-week dual GIP/GLP-1 RA agonist approved for T2DM and its role to reduce cardiovascular events remains to be elucidated. The goal of this trial is to assess how tirzepatide affects the progression of atherosclerotic plaque as determined by multidetector computed tomography angiography (MDCTA).

METHODS

This trial is a double blind, randomized, prospective, placebo-controlled multicenter phase IV trial. Participant eligible for the study will be adults with T2DM between 40 and 80 years of age who have HbA1c ≥ 7.0% to ≤ 10.5% and at least 20% stenosis in major epicardial vessel on CCTA. Baseline examination will include the results of their demographics, lab tests, coronary calcium, as well as coronary plaque volume/composition. Following randomization, tirzepatide or placebo will be given at a weekly dose of 2.5 mg, and a fixed dose-escalation strategy will be followed. Patients will undergo quarterly visits for safety assessments and labs, and follow up with repeat CCTA at 1 year.

DISCUSSION

This study evaluates the antiatherogenic potential of tirzepatide, providing a mechanism of potential CV benefit. This is crucial to our understanding of T2DM treatment and CVD since plaque progression portends worse outcomes in these populations. MDCTA is a noninvasive method that assesses the volume, composition, and degree of coronary vessel stenosis.

CONCLUSION

This study will be the first study to assess the effects of tirzepatide on atherosclerotic plaque progression measured by MDCTA in participants with T2DM.

SGLT2i and GLP1RA effects in patients followed in a hospital diabetology consultation

BACKGROUND

We aimed to investigate the effects of sodium-glucose cotransporter 2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP1RA) in patients with type 2 diabetes mellitus (T2DM) in clinical practice.

RESEARCH DESIGN AND METHODS

A total of 340 patients were included. Data on age, gender, antidiabetic medications, and bioanalytical parameters were collected at baseline and one year later. Were analyzed estimated glomerular filtration rate (eGFR), blood sodium and potassium levels, blood pressure, weight, cardiovascular risk, and glycated hemoglobin (HbA1c).

RESULTS

Patients treated with SGLT2i exhibited a significant improvement in eGFR at the endpoint compared to baseline (p = 0.006). Both treatment groups experienced reductions in systolic blood pressure at the endpoint; especially patients treated with SGLT2i (p = 0.0002). GLP1RA treatment resulted in a statistically significant weight reduction from baseline to endpoint (p < 0.0001), with a higher percentage of patients achieving ≥ 5% weight loss compared to the non-GLP1RA group (33.6% vs. 19.8%). Both SGLT2i and GLP1RA treatments significantly reduced cardiovascular risk scores (p = 0.004 and p = 0.002, respectively). Additionally, both treatments were associated with a significant reduction in HbA1c levels at the endpoint (p = 0.010 and p = 0.002, respectively).

CONCLUSIONS

Our findings suggest that SGLT2i and GLP1RA offer beneficial effects in patients with T2DM.

Tirzepatide: unveiling a new dawn in dual-targeted diabetes and obesity management

INTRODUCTION

Incretin-based therapies have emerged as effective treatments for type 2 diabetes (T2D) and obesity. However, not all patients achieve optimal outcomes with existing treatments, highlighting the need for more effective solutions.

AREAS COVERED

We present a comprehensive evaluation of Tirzepatide (TZP), a novel dual glucose-dependent insulinotropic polypeptide/glucagon-like peptide-1 (GIP/GLP-1) receptor agonist, for managing obesity and T2D. We conducted a systematic search of Cochrane, PubMed, Scopus, and Web of Science databases from inception to April 2024. The focus of the review is on the development and therapeutic potential of TZP, with detailed exploration on pharmacodynamics, pharmacokinetics, clinical efficacy, and safety. Furthermore, it reviews TZP's impacts on glycemic control, weight management, and its potential cardiovascular (CV) benefits.

EXPERT OPINION

TZP represents a significant advancement in the dual-targeted approach to treating T2D and obesity. Its unique mechanism of action offers superior efficacy in reducing glycemic levels and body weight compared to existing therapies. New data suggesting improvements in CV outcomes indicate that TZP could set a new standard in the treatment paradigm. While long-term data on efficacy and safety are still forthcoming, current evidence positions TZP as a promising option for patients who have not reached their therapeutic goals with existing treatments.

Stapled peptides as potential therapeutics for diabetes and other metabolic diseases

The field of peptide drug research has experienced notable progress, with stapled peptides featuring stabilized α-helical conformation, emerging as a promising field. These peptides offer enhanced stability, cellular permeability, and binding affinity and exhibit potential in the treatment of diabetes and metabolic disorders. Stapled peptides, through the disruption of protein-protein interactions, present varied functionalities encompassing agonism, antagonism, and dual-agonism. This comprehensive review offers insight into the technology of peptide stapling and targeting of crucial molecular pathways associated with glucose metabolism, insulin secretion, and food intake. Additionally, we address the challenges in developing stapled peptides, including concerns pertaining to structural stability, peptide helicity, isomer mixture, and potential side effects.

Efficacy and Safety of GLP-1 Medicines for Type 2 Diabetes and Obesity

The development of glucagon-like peptide 1 receptor agonists (GLP-1RA) for type 2 diabetes and obesity was followed by data establishing the cardiorenal benefits of GLP-1RA in select patient populations. In ongoing trials investigators are interrogating the efficacy of these agents for new indications, including metabolic liver disease, peripheral artery disease, Parkinson disease, and Alzheimer disease. The success of GLP-1-based medicines has spurred the development of new molecular entities and combinations with unique pharmacokinetic and pharmacodynamic profiles, exemplified by tirzepatide, a GIP-GLP-1 receptor coagonist. Simultaneously, investigational molecules such as maritide block the GIP and activate the GLP-1 receptor, whereas retatrutide and survodutide enable simultaneous activation of the glucagon and GLP-1 receptors. Here I highlight evidence establishing the efficacy of GLP-1-based medicines, while discussing data that inform safety, focusing on muscle strength, bone density and fractures, exercise capacity, gastrointestinal motility, retained gastric contents and anesthesia, pancreatic and biliary tract disorders, and the risk of cancer. Rapid progress in development of highly efficacious GLP-1 medicines, and anticipated differentiation of newer agents in subsets of metabolic disorders, will provide greater opportunities for use of personalized medicine approaches to improve the health of people living with cardiometabolic disorders.

Application of the integrated data platform combined with dietary management for adults with diabetes: A prospective randomized controlled trial

AIMS

To investigate the efficacy of the integrated data platform of cloud hospital combined with dietary management for adults with type 2 diabetes.

MATERIALS AND METHODS

We conducted a randomized controlled clinical trial. One hundred eighty patients with type 2 diabetes were randomly allocated into a control group (Group A) and an experimental group (Group B). Routine standard diabetes care was applied to the patients in Group A. The integrated data platform with dietary management was applied to Group B. Individualized diabetes education videos were sent to the patients through the platform. The primary endpoint was the change in HbA1c and change in body weight from baseline to Week 12 during the follow-up.

RESULTS

At Week 12, HbA1c was 7.4 ± 0.7%, 6.9 ± 0.9% in Groups A and B, P < 0.01. The rate of fasting blood glucose <7 mmol/L, and glycosylated hemoglobin <7% was higher in Group B than in Group A. At Week 12, there was a significant weight loss and body mass index decrease in the overweight or obese patients of the experimental group. Those overweight or obese patients in the experimental group utilizing the appetite suppressant semaglutide achieved the most significant weight loss, with a 13.4% reduction after 12 weeks.

CONCLUSIONS

The integrated data platform combined with personalized diabetes education video delivery was verified to be a more effective management mode for diabetes. For overweight or obese adults with diabetes, the use of semaglutide in conjunction with dietary management and the integrated data platform led to greater weight loss.

Isoquinoline small molecule ligands are agonists and probe-dependent allosteric modulators of the glucagon subfamily of GPCRs

Class B1 G protein-coupled receptors (GPCRs) are peptide hormone receptors and well validated therapeutic targets, however development of non-peptide drugs targeting this class of receptors is challenging. Recently, a series of isoquinoline-based derivates were reported in the patent literature as allosteric ligands for the glucagon receptor subfamily, and two compounds, LSN3451217 and LSN3556672, were used to facilitate structural studies with the glucagon-like peptide-1 receptor (GLP-1R) and glucose dependent insulinotropic peptide receptor (GIPR) bound to orthosteric agonists. Here we pharmacologically characterized stereoisomers of LSN3451217 and LSN3556672, across the class B1 GPCR family. This revealed LSN3556672 isomers are agonists for the glucagon receptor (GCGR), GLP-1R, GIPR and the calcitonin receptor (CTR), albeit the degree of agonism varied at each receptor. In contrast, LSN3451217 isomers were more selective agonists at the GLP-1R, with lower potency at the GCGR and CTR and no activity at the GIPR. All compounds also modulated peptide-mediated cyclic adenosine monophosphate (cAMP) signaling at the GIPR, and to a lesser extent the GLP-1R, in a probe-dependent manner, with modest positive allosteric modulation observed for some peptides, and negligible effects observed with other peptides. In contrast neutral or weak negative/positive allosteric modulation was observed with peptides assessed at the GCGR and CTR. This study expands our knowledge on class B1 GPCR allosteric modulation and may have implications for future structural and drug discovery efforts targeting the class B1 GPCR subfamily.

Research Progress on Peptide Drugs for Type 2 Diabetes and the Possibility of Oral Administration

Diabetes is a global disease that can lead to a range of complications. Currently, the treatment of type 2 diabetes focuses on oral hypoglycemic drugs and insulin analogues. Studies have shown that drugs such as oral metformin are useful in the treatment of diabetes but can limit the liver's ability to release sugar. The development of glucose-lowering peptides has provided new options for the treatment of type 2 diabetes. Peptide drugs have low oral utilization due to their easy degradation, short half-life, and difficulty passing through the intestinal mucosa. Therefore, improving the oral utilization of peptide drugs remains an urgent problem. This paper reviews the research progress of peptide drugs in the treatment of diabetes mellitus and proposes that different types of nano-formulation carriers, such as liposomes, self-emulsifying drug delivery systems, and polymer particles, should be combined with peptide drugs for oral administration to improve their absorption in the gastrointestinal tract.

Anti-atherosclerotic effect of incretin receptor agonists

Incretin receptor agonists (IRAs), primarily composed of glucagon-like peptide-1 receptor agonists (GLP-1RAs) and glucose-dependent insulinotropic polypeptide receptor agonists (GIPRAs), work by mimicking the actions of the endogenous incretin hormones in the body. GLP-1RAs have been approved for use as monotherapy and in combination with GIPRAs for the management of type 2 diabetes mellitus (T2DM). In addition to their role in glucose regulation, IRAs have demonstrated various benefits such as cardiovascular protection, obesity management, and regulation of bone turnover. Some studies have suggested that IRAs not only aid in glycemic control but also exhibit anti-atherosclerotic effects. These agents have been shown to modulate lipid abnormalities, reduce blood pressure, and preserve the structural and functional integrity of the endothelium. Furthermore, IRAs have the ability to mitigate inflammation by inhibiting macrophage activation and promoting M2 polarization. Research has also indicated that IRAs can decrease macrophage foam cell formation and prevent vascular smooth muscle cell (VSMC) phenotype switching, which are pivotal in atheromatous plaque formation and stability. This review offers a comprehensive overview of the protective effects of IRAs in atherosclerotic disease, with a focus on their impact on atherogenesis.

Effects and mechanisms of long-acting glucagon-like peptide-1 receptor agonist semaglutide on microglia phenotypic transformation and neuroinflammation after cerebral ischemia/reperfusion in rats

BACKGROUND

The optimal method for addressing cerebral ischemic stroke involves promptly restoring blood supply. However, cerebral ischemia-reperfusion injury (CIRI) is an unavoidable consequence of this event. Neuroinflammation is deemed the primary mechanism of CIRI, with various activation phenotypes of microglia playing a pivotal role. Research has demonstrated that long-lasting agonists of the glucagon-like peptide-1 receptor can suppress neuroinflammation and microglial activation.

METHODS

A transient middle cerebral artery occlusion (tMCAO) rat model was established to investigate the effects of semaglutide. Neurological impairments were evaluated utilizing modified neurological severity score on days 1, 3, and 7 postinterventions. Brains were stained with 2,3,5-Triphenyltetrazolium Chloride to determine infarct volume. To assess the expression of various microglia activation phenotypes and neuroinflammatory biomarkers, we utilized immunohistochemistry and immunoblotting.

RESULTS

The study demonstrated that semaglutide in the tMCAO model could decrease neurological deficit scores and reduce the size of cerebral infarcts. In addition, we observed low levels of cluster of differentiation 68 (CD68, an indicator of M1 microglial activation) and tumor necrosis factor alpha (a pro-inflammatory mediator). Moreover, the results indicated a rise in the levels of CD206 (an indicator of M2 activation) and transforming growth factor beta (an anti-inflammatory mediator), while simultaneously reducing P65 levels in the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling cascade.

CONCLUSION

In the CIRI model, semaglutide exhibits notable neuroprotective effects on rats, reducing neuroinflammation through the regulation of microglia phenotype transformation and inhibition of NF-κB activation.

DPP-4 inhibitors sitagliptin and PF-00734,200 mitigate dopaminergic neurodegeneration, neuroinflammation and behavioral impairment in the rat 6-OHDA model of Parkinson's disease

Epidemiological studies report an elevated risk of Parkinson's disease (PD) in patients with type 2 diabetes mellitus (T2DM) that is mitigated in those prescribed dipeptidyl peptidase 4 (DPP-4) inhibitors. With an objective to characterize clinically translatable doses of DPP-4 inhibitors (gliptins) in a well-characterized PD rodent model, sitagliptin, PF-00734,200 or vehicle were orally administered to rats initiated either 7-days before or 7-days after unilateral medial forebrain bundle 6-hydroxydopamine (6-OHDA) lesioning. Measures of dopaminergic cell viability, dopamine content, neuroinflammation and neurogenesis were evaluated thereafter in ipsi- and contralateral brain. Plasma and brain incretin and DPP-4 activity levels were quantified. Furthermore, brain incretin receptor levels were age-dependently evaluated in rodents, in 6-OHDA challenged animals and human subjects with/without PD. Cellular studies evaluated neurotrophic/neuroprotective actions of combined incretin administration. Pre-treatment with oral sitagliptin or PF-00734,200 reduced methamphetamine (meth)-induced rotation post-lesioning and dopaminergic degeneration in lesioned substantia nigra pars compacta (SNc) and striatum. Direct intracerebroventricular gliptin administration lacked neuroprotective actions, indicating that systemic incretin-mediated mechanisms underpin gliptin-induced favorable brain effects. Post-treatment with a threefold higher oral gliptin dose, likewise, mitigated meth-induced rotation, dopaminergic neurodegeneration and neuroinflammation, and augmented neurogenesis. These gliptin-induced actions associated with 70-80% plasma and 20-30% brain DPP-4 inhibition, and elevated plasma and brain incretin levels. Brain incretin receptor protein levels were age-dependently maintained in rodents, preserved in rats challenged with 6-OHDA, and in humans with PD. Combined GLP-1 and GIP receptor activation in neuronal cultures resulted in neurotrophic/neuroprotective actions superior to single agonists alone. In conclusion, these studies support further evaluation of the repurposing of clinically approved gliptins as a treatment strategy for PD.

Sitagliptin elevates plasma and CSF incretin levels following oral administration to nonhuman primates: relevance for neurodegenerative disorders

The endogenous incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) possess neurotrophic, neuroprotective, and anti-neuroinflammatory actions. The dipeptidyl peptidase 4 (DPP-4) inhibitor sitagliptin reduces degradation of endogenous GLP-1 and GIP, and, thereby, extends the circulation of these protective peptides. The current nonhuman primate (NHP) study evaluates whether human translational sitagliptin doses can elevate systemic and central nervous system (CNS) levels of GLP-1/GIP in naive, non-lesioned NHPs, in line with our prior rodent studies that demonstrated sitagliptin efficacy in preclinical models of Parkinson's disease (PD). PD is an age-associated neurodegenerative disorder whose current treatment is inadequate. Repositioning of the well-tolerated and efficacious diabetes drug sitagliptin provides a rapid approach to add to the therapeutic armamentarium for PD. The pharmacokinetics and pharmacodynamics of 3 oral sitagliptin doses (5, 20, and 100 mg/kg), equivalent to the routine clinical dose, a tolerated higher clinical dose and a maximal dose in monkey, were evaluated. Peak plasma sitagliptin levels were aligned both with prior reports in humans administered equivalent doses and with those in rodents demonstrating reduction of PD associated neurodegeneration. Although CNS uptake of sitagliptin was low (cerebrospinal fluid (CSF)/plasma ratio 0.01), both plasma and CSF concentrations of GLP-1/GIP were elevated in line with efficacy in prior rodent PD studies. Additional cellular studies evaluating human SH-SY5Y and primary rat ventral mesencephalic cultures challenged with 6-hydroxydopamine, established cellular models of PD, demonstrated that joint treatment with GLP-1 + GIP mitigated cell death, particularly when combined with DPP-4 inhibition to maintain incretin levels. In conclusion, this study provides a supportive translational step towards the clinical evaluation of sitagliptin in PD and other neurodegenerative disorders for which aging, similarly, is the greatest risk factor.

GLP-1 receptor agonist-based therapies and cardiovascular risk: a review of mechanisms

Cardiovascular outcome trials (CVOTs) in people living with type 2 diabetes mellitus and obesity have confirmed the cardiovascular benefits of glucagon-like peptide 1 receptor agonists (GLP-1RAs), including reduced cardiovascular mortality, lower rates of myocardial infarction, and lower rates of stroke. The cardiovascular benefits observed following GLP-1RA treatment could be secondary to improvements in glycemia, blood pressure, postprandial lipidemia, and inflammation. Yet, the GLP-1R is also expressed in the heart and vasculature, suggesting that GLP-1R agonism may impact the cardiovascular system. The emergence of GLP-1RAs combined with glucose-dependent insulinotropic polypeptide and glucagon receptor agonists has shown promising results as new weight loss medications. Dual-agonist and tri-agonist therapies have demonstrated superior outcomes in weight loss, lowered blood sugar and lipid levels, restoration of tissue function, and enhancement of overall substrate metabolism compared to using GLP-1R agonists alone. However, the precise mechanisms underlying their cardiovascular benefits remain to be fully elucidated. This review aims to summarize the findings from CVOTs of GLP-1RAs, explore the latest data on dual and tri-agonist therapies, and delve into potential mechanisms contributing to their cardioprotective effects. It also addresses current gaps in understanding and areas for further research.

Glucagon-like peptide-1 receptor: mechanisms and advances in therapy

The glucagon-like peptide-1 (GLP-1) receptor, known as GLP-1R, is a vital component of the G protein-coupled receptor (GPCR) family and is found primarily on the surfaces of various cell types within the human body. This receptor specifically interacts with GLP-1, a key hormone that plays an integral role in regulating blood glucose levels, lipid metabolism, and several other crucial biological functions. In recent years, GLP-1 medications have become a focal point in the medical community due to their innovative treatment mechanisms, significant therapeutic efficacy, and broad development prospects. This article thoroughly traces the developmental milestones of GLP-1 drugs, from their initial discovery to their clinical application, detailing the evolution of diverse GLP-1 medications along with their distinct pharmacological properties. Additionally, this paper explores the potential applications of GLP-1 receptor agonists (GLP-1RAs) in fields such as neuroprotection, anti-infection measures, the reduction of various types of inflammation, and the enhancement of cardiovascular function. It provides an in-depth assessment of the effectiveness of GLP-1RAs across multiple body systems-including the nervous, cardiovascular, musculoskeletal, and digestive systems. This includes integrating the latest clinical trial data and delving into potential signaling pathways and pharmacological mechanisms. The primary goal of this article is to emphasize the extensive benefits of using GLP-1RAs in treating a broad spectrum of diseases, such as obesity, cardiovascular diseases, non-alcoholic fatty liver disease (NAFLD), neurodegenerative diseases, musculoskeletal inflammation, and various forms of cancer. The ongoing development of new indications for GLP-1 drugs offers promising prospects for further expanding therapeutic interventions, showcasing their significant potential in the medical field.

Principal components analysis on genes related to inflammasome complex and microglial activation in the hypothalamus of obese mice treated with semaglutide (GLP-1 analog)

We studied the effect of semaglutide (glucagon-like peptide type 1 agonist) on hypothalamic pro-inflammatory genes in diet-induced obese mice. Male C57BL/6J mice were fed a control (C) or high-fat (HF) diet for 16 weeks, then divided into six groups and maintained for an additional four-week study: C, C+semaglutide (CS), C pair-feeding (CP), HF, HF+semaglutide (HFS), and HF pair-feeding (HFP).Weight gain (WG), food efficiency (FE), and plasmatic biochemistry were determined. The hypothalamus was removed and prepared for molecular analysis. Semaglutide reduced WG and FE in the HF group. High cytokines levels (tumor necrosis factor alpha, TNF alpha, monocyte chemoattractant protein 1, MCP1, and Resistin) in HF mice were reduced in HFS mice. High pro-inflammatory gene expressions were seen in HF (toll-like receptor 4, Tlr4; Mcp1; interleukin 6, Il6; Tnfa), inflammasome complex (Pirina domain-containing receptor 3, Nlrp3; Caspase 1, Il1b, Il18), and microglial activation (ionized calcium-binding adapter molecule 1, Iba1; cluster differentiation 68, Cd68; argirase 1, Arg1) but mitigated in HFS. The principal components analysis (PCA) based on these markers in a PC1 x PC2 scatterplot put HF and HFP together but far away from a cluster formed by C and HFS, indicating little significance of weight loss (HFP) but decisive action of semaglutide (HFS) in the results. In conclusion, semaglutide benefits hypothalamic pro-inflammatory genes, inflammasome complex, and microglial activation independent of the weight loss effect. Since GLP-1 receptor agonists such as semaglutide are already indicated to treat obesity and diabetes, the potential translational effects on neuroinflammation should be considered.

Machine learning designs new GCGR/GLP-1R dual agonists with enhanced biological potency

Several peptide dual agonists of the human glucagon receptor (GCGR) and the glucagon-like peptide-1 receptor (GLP-1R) are in development for the treatment of type 2 diabetes, obesity and their associated complications. Candidates must have high potency at both receptors, but it is unclear whether the limited experimental data available can be used to train models that accurately predict the activity at both receptors of new peptide variants. Here we use peptide sequence data labelled with in vitro potency at human GCGR and GLP-1R to train several models, including a deep multi-task neural-network model using multiple loss optimization. Model-guided sequence optimization was used to design three groups of peptide variants, with distinct ranges of predicted dual activity. We found that three of the model-designed sequences are potent dual agonists with superior biological activity. With our designs we were able to achieve up to sevenfold potency improvement at both receptors simultaneously compared to the best dual-agonist in the training set.

Tirzepatide shows neuroprotective effects via regulating brain glucose metabolism in APP/PS1 mice

Tirzepatide (LY3298176), a GLP-1 and GIP receptor agonist, is fatty-acid-modified and 39-amino acid linear peptide, which ameliorates learning and memory impairment in diabetic rats. However, the specific molecular mechanism remains unknown. In the present study, we investigated the role of tirzepatide in the neuroprotective effects in Alzheimer's disease (AD) model mice. Tirzepatide was administrated intraperitoneal (i.p.) APP/PS1 mice for 8 weeks with at 10 nmol/kg once-weekly, it significantly decreased the levels of GLP-1R, and GFAP protein expression and amyloid plaques in the cortex, it also lowered neuronal apoptosis induced by amyloid-β (Aβ), but did not affect the anxiety and cognitive function in APP/PS1 mice. Moreover, tirzepatide reduced the blood glucose levels and increased the mRNA expression of GLP-1R, SACF1, ATF4, Glu2A, and Glu2B in the hypothalamus of APP/PS1 mice. Tirzepatide increased the mRNA expression of glucose transporter 1, hexokinase, glucose-6-phosphate dehydrogenase, and phosphofructokinase in the cortex. Lastly, tirzepatide improved the energetic metabolism by regulated reactive oxygen species production and mitochondrial membrane potential caused by Aβ, thereby decreasing mitochondrial function and ATP levels in astrocytes through GLP-1R. These results provide valuable insights into the mechanism of brain glucose metabolism and mitochondrial function of tirzepatide, presenting potential strategies for AD treatment.

A metabolic balance of GLP-1 and NMDA receptors in the brain

Glucagon-like peptide-1 (GLP-1) and N-methyl-D-aspartate (NMDA) receptors in the brain regulate metabolic homeostasis. In a paper published in Nature, Petersen et al. describe a bimodal molecule that conjugates a GLP-1 analog with MK-801 (NMDA receptor antagonist), which lowers feeding and body weight to a greater extent than the GLP-1R agonist alone.

Diabetes and Osteoarthritis: Exploring the Interactions and Therapeutic Implications of Insulin, Metformin, and GLP-1-Based Interventions

Diabetes mellitus (DM) and osteoarthritis (OA) are prevalent chronic conditions with shared pathophysiological links, including inflammation and metabolic dysregulation. This study investigates the potential impact of insulin, metformin, and GLP-1-based therapies on OA progression. Methods involved a literature review of clinical trials and mechanistic studies exploring the effects of these medications on OA outcomes. Results indicate that insulin, beyond its role in glycemic control, may modulate inflammatory pathways relevant to OA, potentially influencing joint health. Metformin, recognized for its anti-inflammatory properties via AMPK activation, shows promise in mitigating OA progression by preserving cartilage integrity and reducing inflammatory markers. GLP-1-based therapies, known for enhancing insulin secretion and improving metabolic profiles in DM, also exhibit anti-inflammatory effects that may benefit OA by suppressing cytokine-mediated joint inflammation and supporting cartilage repair mechanisms. Conclusions suggest that these medications, while primarily indicated for diabetes management, hold therapeutic potential in OA by targeting common underlying mechanisms. Further clinical trials are warranted to validate these findings and explore optimal therapeutic strategies for managing both DM and OA comorbidities effectively.

Dulaglutide restores endothelial progenitor cell levels in diabetic mice and mitigates high glucose-induced endothelial injury through SIRT1-mediated mitochondrial fission

Type 2 diabetes mellitus (T2DM) significantly impairs the functionality and number of endothelial progenitor cells (EPCs) and resident endothelial cells, critical for vascular repair and regeneration, exacerbating the risk of vascular complications. GLP-1 receptor agonists, like dulaglutide, have emerged as promising therapeutic agents due to their multifaceted effects, including the enhancement of EPC activity and protection of endothelial cells. This study investigates dulaglutide's effects on peripheral blood levels of CD34+ and CD133+ cells in a mouse model of lower limb ischemia and its protective mechanisms against high-glucose-induced damage in endothelial cells. Results demonstrated that dulaglutide significantly improves blood flow, reduces tissue damage and inflammation in ischemic limbs, and enhances glycemic control. Furthermore, dulaglutide alleviated high-glucose-induced endothelial cell damage, evident from improved tube formation, reduced reactive oxygen species accumulation, and restored endothelial junction integrity. Mechanistically, dulaglutide mitigated mitochondrial fission in endothelial cells under high-glucose conditions, partly through maintaining SIRT1 expression, which is crucial for mitochondrial dynamics. This study reveals the potential of dulaglutide as a therapeutic option for vascular complications in T2DM patients, highlighting its role in improving endothelial function and mitochondrial integrity.

The emerging role of glucagon-like peptide 1 in binge eating

Binge eating is a central component of two clinical eating disorders: binge eating disorder and bulimia nervosa. However, the large treatment gap highlights the need to identify other strategies to decrease binge eating. Novel pharmacotherapies may be one such approach. Glucagon-like peptide-1 (GLP-1) is an intestinal and brain-derived neuroendocrine signal with a critical role in promoting glycemic control through its incretin effect. Additionally, the energy balance effects of GLP-1 are well-established; activation of the GLP-1 receptor (GLP-1R) reduces food intake and body weight. Aligned with these beneficial metabolic effects, there are GLP-1R agonists that are currently used for the treatment of diabetes and obesity. A growing body of literature suggests that GLP-1 may also play an important role in binge eating. Dysregulation of the endogenous GLP-1 system is associated with binge eating in non-human animal models, and GLP-1R agonists may be a promising approach to suppress the overconsumption that occurs during binge eating. Here, we briefly discuss the role of GLP-1 in normal energy intake and reward and then review the emerging evidence suggesting that disruptions to GLP-1 signaling are associated with binge eating. We also consider the potential utility of GLP-1-based pharmacotherapies for reducing binge eating behavior.

Comparative Efficacy and Safety of Glucagon-like Peptide-1 Receptor Agonists in Children and Adolescents with Obesity or Overweight: A Systematic Review and Network Meta-Analysis

Four glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have been used in children and adolescents with obesity or overweight. This network meta-analysis was conducted to compare the efficacy and safety of these regimens. Embase, PubMed, and Scopus were searched on March 2023 and updated in June 2024 for eligible randomized controlled trials (RCTs). The primary efficacy outcomes were mean difference in actual body weight, BMI (body mass index), BMI z score, and waist circumference. Safety outcomes included nausea, vomiting, diarrhea, abdominal pain, injection-site reaction, and hypoglycemia. Eleven RCTs with 953 participants were eligible. Semaglutide exhibited greater effects in reducing weight, BMI, and BMI z score versus the placebo. Semaglutide was associated with greater weight loss and BMI z score reduction in comparison with exenatide, liraglutide, and dulaglutide. Semaglutide also significantly decreased BMI than exenatide. None of the four GLP-1 RAs were associated with higher risks of diarrhea, headache, and abdominal pain versus the placebo. Liraglutide was more likely to cause nausea, vomiting, hypoglycemia, and injection-site reactions than the placebo. Liraglutide also had higher odds of causing injection-site reactions than other GLP-1 RAs. Semaglutide appeared to be the most effective and safe option among four GLP-1 RAs in children and adolescents with obesity or overweight.

Intra-islet α-cell Gs signaling promotes glucagon release

Glucagon, a hormone released from pancreatic α-cells, is critical for maintaining euglycemia and plays a key role in the pathophysiology of diabetes. To stimulate the development of new classes of therapeutic agents targeting glucagon release, key α-cell signaling pathways that regulate glucagon secretion need to be identified. Here, we focused on the potential importance of α-cell Gs signaling on modulating α-cell function. Studies with α-cell-specific mouse models showed that activation of α-cell Gs signaling causes a marked increase in glucagon secretion. We also found that intra-islet adenosine plays an unexpected autocrine/paracrine role in promoting glucagon release via activation of α-cell Gs-coupled A2A adenosine receptors. Studies with α-cell-specific Gαs knockout mice showed that α-cell Gs also plays an essential role in stimulating the activity of the Gcg gene, thus ensuring proper islet glucagon content. Our data suggest that α-cell enriched Gs-coupled receptors represent potential targets for modulating α-cell function for therapeutic purposes.

Obesity management for the treatment of type 2 diabetes: emerging evidence and therapeutic approaches

Excess adiposity can contribute to metabolic complications, such as type 2 diabetes mellitus (T2DM), which poses a significant global health burden. Traditionally viewed as a chronic and irreversible condition, T2DM management has evolved and new approaches emphasizing reversal and remission are emerging. Bariatric surgery demonstrates significant improvements in body weight and glucose homeostasis. However, its complexity limits widespread implementation as a population-wide intervention. The identification of glucagon-like peptide 1 (GLP-1) and the development of GLP-1 receptor agonists (GLP-1RAs) have improved T2DM management and offer promising outcomes in terms of weight loss. Innovative treatment approaches combining GLP-1RA with other gut and pancreatic-derived hormone receptor agonists, such as glucose-dependant insulinotropic peptide (GIP) and glucagon (GCG) receptor agonists, or coadministered with amylin analogues, are demonstrating enhanced efficacy in both weight loss and glycemic control. This review aims to explore the benefits of bariatric surgery and emerging pharmacological therapies such as GLP-1RAs, and dual and triple agonists in managing obesity and T2DM while highlighting the caveats and evolving landscape of treatment options.

Immunomodulation and inflammation: Role of GLP-1R and GIPR expressing cells within the gut

Glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are peptide hormones produced by enteroendocrine cells in the small intestine. Despite being produced in the gut, the leveraging of their role in potentiating glucose-stimulated insulin secretion, also known as the incretin effect, has distracted from discernment of direct intestinal signaling circuits. Both preclinical and clinical evidence have highlighted a role for the incretins in inflammation. In this review, we highlight the discoveries of GLP-1 receptor (GLP-1R)+ natural (TCRαβ and TCRγδ) and induced (TCRαβ+CD4+ cells and TCRαβ+CD8αβ+) intraepithelial lymphocytes. Both endogenous signaling and pharmacological activation of GLP-1R impact local and systemic inflammation, the gut microbiota, whole-body metabolism, as well as the control of GLP-1 bioavailability. While GIPR signaling has been documented to impact hematopoiesis, the impact of these bone marrow-derived cells in gut immunology is not well understood. We uncover gaps in the literature of the evaluation of the impact of sex in these GLP-1R and GIP receptor (GIPR) signaling circuits and provide speculations of the maintenance roles these hormones play within the gut in the fasting-refeeding cycles. GLP-1R agonists and GLP-1R/GIPR agonists are widely used as treatments for diabetes and weight loss, respectively; however, their impact on gut homeostasis has not been fully explored. Advancing our understanding of the roles of GLP-1R and GIPR signaling within the gut at homeostasis as well as metabolic and inflammatory diseases may provide targets to improve disease management.

Role of lifestyle and glucagon-like peptide-1 receptor agonists for weight loss in obesity, type 2 diabetes and steatotic liver diseases

BACKGROUND

The current obesity pandemic has given rise to associated comorbidities and complications, including type 2 diabetes and metabolic dysfunction-associated steatotic liver disease (MASLD). During the last decade, certain glucagon-like peptide 1 receptor agonists (GLP-1RA), originally developed as antihyperglycemic drugs, also demonstrated efficacy for weight loss.

AIMS

To review shared pathophysiologic features of common metabolic diseases and compare therapeutic strategies to reduce body weight and related complications.

METHODS

We performed an extensive literature research to describe the effects of lifestyle modification, first-generation anti-obesity drugs, and GLP-1RA on weight loss in humans with obesity, type 2 diabetes and MASLD.

RESULTS

Until recently, treatment of obesity has been limited to lifestyle modification, which offer moderate degree and sustainability of weight loss. The few approved first-generation anti-obesity drugs are either limited to short term use or to certain forms of obesity. Some GLP-1RA significantly decrease caloric intake and body weight. Liraglutide and semaglutide have therefore been approved for treating people with obesity. They also lead to a reduction of hepatic fat content and inflammation in people with biopsy-confirmed MASLD. Possible limitations comprise adverse effects, treatment adherence and persistence.

CONCLUSION

Certain GLP-1RA are superior to lifestyle modification and first-generation anti-obesity drugs in inducing weight loss. They have therefore markedly changed the portfolio of obesity treatment with additional beneficial effects on steatotic liver disease.

Customizable Click Biochemistry Strategy for the Design and Preparation of Glucagon-like Peptide-1 Conjugates and Coagonists

The development of oligomeric glucagon-like peptide-1 (GLP-1) and GLP-1-containing coagonists holds promise for enhancing the therapeutic potential of the GLP-1-based drugs for treating type 2 diabetes mellitus (T2DM). Here, we report a facile, efficient, and customizable strategy based on genetically encoded SpyCatcher-SpyTag chemistry and an inducible, cleavable self-aggregating tag (icSAT) scheme. icSAT-tagged SpyTag-fused GLP-1 and the dimeric or trimeric SpyCatcher scaffold were designed for dimeric or trimeric GLP-1, while icSAT-tagged SpyCatcher-fused GLP-1 and the icSAT-tagged SpyTag-fused GIP were designed for dual GLP-1/GIP (glucose-dependent insulinotropic polypeptide) receptor agonist. These SpyCatcher- and SpyTag-fused protein pairs were spontaneously ligated directly from the cell lysates. The subsequent icSAT scheme, coupled with a two-step standard column purification, resulted in target proteins with authentic N-termini, with yields ranging from 35 to 65 mg/L and purities exceeding 99%. In vitro assays revealed 3.0- to 4.1-fold increased activities for dimeric and trimeric GLP-1 compared to mono-GLP-1. The dual GLP-1/GIP receptor agonist exhibited balanced activity toward the GLP-1 receptor or the GIP receptor. All the proteins exhibited 1.8- to 3.0-fold prolonged half-lives in human serum compared to mono-GLP-1 or GIP. This study provides a generally applicable click biochemistry strategy for developing oligomeric or dual peptide/protein-based drug candidates.

Glucagon kinetics assessed by mathematical modelling during oral glucose administration in people spanning from normal glucose tolerance to type 2 diabetes

Background/Objectives

Glucagon is important in the maintenance of glucose homeostasis, with also effects on lipids. In this study, we aimed to apply a recently developed model of glucagon kinetics to determine the sensitivity of glucagon variations (especially, glucagon inhibition) to insulin levels ("alpha-cell insulin sensitivity"), during oral glucose administration.

Subjects/Methods

We studied 50 participants (spanning from normal glucose tolerance to type 2 diabetes) undergoing frequently sampled 5-hr oral glucose tolerance test (OGTT). The alpha-cell insulin sensitivity and the glucagon kinetics were assessed by a mathematical model that we developed previously.

Results

The alpha-cell insulin sensitivity parameter (named SGLUCA; "GLUCA": "glucagon") was remarkably variable among participants (CV=221%). SGLUCA was found inversely correlated with the mean glycemic values, as well as with 2-hr glycemia of the OGTT. When stratifying participants into two groups (normal glucose tolerance, NGT, N=28, and impaired glucose regulation/type 2 diabetes, IGR_T2D, N=22), we found that SGLUCA was lower in the latter (1.50 ± 0.50·10-2 vs. 0.26 ± 0.14·10-2 ng·L-1 GLUCA/pmol·L-1 INS, in NGT and IGR_T2D, respectively, p=0.009; "INS": "insulin").

Conclusions

The alpha-cell insulin sensitivity is highly variable among subjects, and it is different in groups at different glucose tolerance. This may be relevant for defining personalized treatment schemes, in terms of dietary prescriptions but also for treatments with glucagon-related agents.