Diabetes is a chronic metabolic disorder with high incidence and prevalence worldwide. This study explores a novel glucagon-like peptide-1-Fc (GLP-1-Fc) mRNA designed to improve diabetes management by inducing stable and persistent production of GLP-1-Fc protein.

The GLP-1-Fc mRNA was generated using in vitro transcription and fusion protein technology. Protein expression was assessed via western blot and enzyme-linked immunosorbent assay (ELISA) in Human Embryonic Kidney 293T (HEK293T) cells. GLP-1-Fc mRNA and GLP-1-Fc protein (dulaglutide) were administered to C57BL/6J and db/db mice to evaluate protein levels, GLP-1 receptor activity, hypoglycemic effects, and safety using ELISA, lance ultra cAMP assay, blood glucose levels detection, immunofluorescence, and hematoxylin and eosin staining.

The designed mRNA fused with the Fc region successfully encoded GLP-1-Fc, showing optimal stability and translation efficiency. The GLP-1-Fc protein levels were significantly higher in the GLP-1-Fc mRNA treatment group than those in the control mice. The GLP-1-Fc mRNA effectively reduced blood glucose levels and increased GLP-1 receptor expression in db/db mice after both single and repeated administrations. Moreover, the GLP-1-Fc mRNA provided prolonged glucose reduction with similar efficacy to GLP-1 protein drug, dulaglutide. Besides, intraperitoneal delivery of GLP-1-Fc mRNA does not induce tissue damage.

Compared to conventional peptide-based therapies, GLP-1-Fc mRNA represents a promising strategy for diabetes treatment by enabling sustained in vivo protein expression, achieving effective glycemic control, and offering a streamlined manufacturing process with reduced production complexity.

Glucagon-like peptide 1 receptor agonists (GLP1RAs) have rapidly changed the landscape of diabetes and obesity treatment. Enthusiasm for their use is tempered with concerns regarding their risk for inducing C-cell tumors based on preclinical studies in rodents. A black-box warning from the US Food and Drug Administration recommends against using GLP1RA in patients with a personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2A or 2B (MEN2), providing clear guidance regarding this cohort of patients. However, emerging data also suggest an increased incidence of differentiated thyroid cancer (DTC) in patients treated with these agents. Other studies, though, have not confirmed an association between GLP1RAs and DTC. With conflicting results concerning thyroid cancer risk, there is no clear consensus regarding the optimal approach to screening patients prior to initiating the medications and/or evaluating for thyroid cancer during GLP1RA treatment. Within the context of patient cases, this review will summarize the existing data, describe ongoing controversies, and outline future areas for research regarding thyroid cancer risk with GLP1RA use.

Glucose-dependent insulinotropic polypeptide (GIP) was the first incretin identified and plays an essential role in the maintenance of glucose tolerance in healthy humans. Until recently GIP had not been developed as a therapeutic and thus has been overshadowed by the other incretin, glucagon-like peptide 1 (GLP-1), which is the basis for several successful drugs to treat diabetes and obesity. However, there has been a rekindling of interest in GIP biology in recent years, in great part due to pharmacology demonstrating that both GIPR agonism and antagonism may be beneficial in treating obesity and diabetes. This apparent paradox has reinvigorated the field, led to new lines of investigation, and deeper understanding of GIP.

In this review, we provide a detailed overview on the multifaceted nature of GIP biology and discuss the therapeutic implications of GIPR signal modification on various diseases.

Following its classification as an incretin hormone, GIP has emerged as a pleiotropic hormone with a variety of metabolic effects outside the endocrine pancreas. The numerous beneficial effects of GIPR signal modification render the peptide an interesting candidate for the development of pharmacotherapies to treat obesity, diabetes, drug-induced nausea and both bone and neurodegenerative disorders.

Dipeptidyl Peptidase 9 (DPP9) is a prolyl amino dipeptidylpeptidase that can cut a post-proline peptide bond at the penultimate position at the N-terminus. By removing N-terminal prolines, this intracellular peptidase acts as an upstream regulator of the N-degron pathway. DPP9 has crucial roles in inflammatory regulation, DNA repair, cellular homeostasis, and cellular proliferation, while its deregulation is linked to cancer and immunological disorders. Currently, there is no fully selective chemical inhibitor and the DPP9 knockout transgenic mouse model is conditional. Mice and humans in which DPP9 catalytic activity is absent die neonatally. DPP9 inhibition for manipulating DPP9 activity in vivo has potential uses and there is rapid progress towards DPP9 selectivity, with 170x selectivity achieved. This review discusses roles of DPP9 in biology and diseases and potential applications of compounds that inhibit DPP9 and its related proteases.

Peptide hormones are fundamental regulators of biological processes involved in homeostasis regulation and are often dysregulated in endocrine diseases. Despite their biological significance and established therapeutic potential, there is still a gap in our knowledge of their processing and post-translational modifications, as well as in the technologies for their discovery and detection. In this review, we cover insights into the peptidome landscape, including the proteolytic processing and post-translational modifications of peptide hormones. Understanding the full landscape of peptide hormones and their modifications could provide insights into leveraging proteolytic mechanisms to identify novel peptides with therapeutic potential. Therefore, we also discuss the need for future research aiming at better predicting, detecting, and characterizing new peptides with biological activities.

The gut-brain axis (GBA) is involved in the modulation of multiple physiological activities, and the vagus nerve plays an important role in this process. However, the association between vagus nerve function and nutritional regulation remains unclear. Here, we explored changes in the nutritional status of mice after vagotomy and investigated the underlying mechanisms responsible for these changes.

We performed vagotomies in mice and verified nerve resection using immunofluorescence staining. We then observed the food intake and body weight of the mice and tested nutritional and inflammation-related markers using enzyme-linked immunosorbent assay (ELISA) kits. The role of glucagon-like peptide 1 (GLP-1) in the GBA was determined using qRT-PCR and ELISA kits. Western blot and ELISA kits were used to explore the underlying mechanisms.

After vagotomy, the mice experienced a deterioration in their nutritional status, which manifested as a significant reduction in body weight and food intake. The expression of the proglucagon gene (GCG), which encodes GLP-1, significantly increased after vagotomy. Mechanistically, acetylcholine (ACh) reversed the HG (high glucose) -induced elevation of GLP-1 secretion. ACh upregulated AMPKα phosphorylation, thereby reducing GLP-1 secretion. Moreover, the level of AMPKα phosphorylation was enhanced by ACh via M3AChR.

ACh released by the vagus nerve counteracts the anorectic effects of GLP-1 under normal physiological conditions. Vagotomy blocks this feedback, resulting in a loss of food intake and body weight in mice.

Neurodegenerative diseases (NDDs) represent a heterogeneous group of disorders characterized by progressive neuronal loss, which results in significant deficits in memory, cognition, motor skills, and sensory functions. As the prevalence of NDDs rises, there is an urgent unmet need for effective therapies. Current drug development approaches primarily target single pathological features of the disease, which could explain the limited efficacy observed in late-stage clinical trials. Originally developed for the treatment of obesity and diabetes, incretin-based therapies, particularly long-acting GLP-1 receptor (GLP-1R) agonists and GLP-1R-gastric inhibitory polypeptide receptor (GIPR) dual agonists, are emerging as promising treatments for NDDs. Despite limited conclusive preclinical evidence, their pleiotropic ability to reduce neuroinflammation, enhance neuronal energy metabolism and promote synaptic plasticity positions them as potential disease-modifying NDD interventions. In anticipation of results from larger clinical trials, continued advances in next-generation incretin mimetics offer the potential for improved brain access and enhanced neuroprotection, paving the way for incretin-based therapies as a future cornerstone in the management of NDDs.

The antihyperglycemic effect of black tea is well-known, and theaflavins (TFs) are considered active compounds. It is, however, unclear whether glucagon-like peptide-1 (GLP-1) is involved in the antihyperglycemic effects of TFs. We demonstrate that TFs suppress postprandial hyperglycemia by stimulating GLP-1 secretion in mice. In STC-1 cells, theaflavin 3'-gallate (TF2B), possessing a galloyl group at the 3'-position, showed the strongest effect on GLP-1 secretion among the four TFs. TF2B activated G protein-coupled receptor 55 (GPR55) and was confirmed to bind to the receptor, notably exhibiting the highest binding affinity. Moreover, GPR55 antagonist canceled TF2B-induced GLP-1 secretion. Downstream, TF2B increased intracellular Ca2+ levels and activated the Ca2+/calmodulin-dependent protein kinase II (CaMKII) and extracellular signal-regulated kinases 1/2 (ERK1/2) pathways. Inhibitors of Ca2+ signaling, CaMKII, and ERK pathways abolished TF2B-stimulated GLP-1 secretion. These findings suggest that TF2B from black tea prevents hyperglycemia through GPR55-dependent stimulation of GLP-1 secretion via Ca2+-Ca2+/CaMKII and ERK1/2 pathways.

Glucagon-like peptide-1 (GLP-1), a hormone released from enteroendocrine cells in the distal small and large intestines in response to nutrients and other stimuli, not only controls eating and insulin release, but is also involved in drinking control as well as renal and cardiovascular functions. Moreover, GLP-1 functions as a central nervous system peptide transmitter, produced by preproglucagon (PPG) neurons in the hindbrain. Intestinal GLP-1 inhibits eating by activating vagal sensory neurons directly, via GLP-1 receptors (GLP-1Rs), but presumably also indirectly, by triggering the release of serotonin from enterochromaffin cells. GLP-1 enhances glucose-dependent insulin release via a vago-vagal reflex and by direct action on beta cells. Finally, intestinal GLP-1 acts on the kidneys to modulate electrolyte and water movements, and on the heart, where it provides numerous benefits, including anti-inflammatory, antiatherogenic, and vasodilatory effects, as well as protection against ischemia/reperfusion injury and arrhythmias. Hindbrain PPG neurons receive multiple inputs and project to many GLP-1R-expressing brain areas involved in reward, autonomic functions, and stress. PPG neuron-derived GLP-1 is involved in the termination of large meals and is implicated in the inhibition of water intake. This review details GLP-1's roles in these interconnected systems, highlighting recent findings and unresolved issues, and integrating them to discuss the physiological and pathological relevance of endogenous GLP-1 in coordinating these functions. As eating poses significant threats to metabolic, fluid, and immune homeostasis, the body needs mechanisms to mitigate these challenges while sustaining essential nutrient intake. Endogenous GLP-1 plays a crucial role in this "ingestive homeostasis."

Dipeptide production mediated by dipeptidyl-peptidase (DPP)4, DPP5, DPP7, and DPP11 plays a crucial role in growth of Porphyromonas gingivalis, a periodontopathic asaccharolytic bacterium. Given the particular P1-position specificity of DPPs, it has been speculated that DPP5 or DPP7 might be responsible for degrading refractory P1 amino acids, i.e., neutral (Thr, His, Gly, Ser, Gln) and hydrophilic (Asn) residues. The present results identified DPP7 as an entity that processes these residues, thus ensuring complete production of nutritional dipeptides in the bacterium. Activity enhancement by the P1' residue was observed in DPP7, as well as DPP4 and DPP5. Toward the refractory P1 residues, DPP7 uniquely hydrolyzed HX|LD-MCA (X = His, Gln, or Asn) and their hydrolysis was most significantly suppressed in dpp7 gene-disrupted cells. Additionally, hydrophobic P2 residue significantly enhanced DPP7 activity toward these substrates. The findings propose a comprehensive 20 P1 × 20 P2 amino acid matrix showing the coordination of four DPPs to achieve complete dipeptide production along with subsidiary peptidases. The present finding of a broad substrate specificity that DPP7 accounts for releasing 48 % (192/400) of N-terminal dipeptides could implicate its potential role in linking periodontopathic disease to related systemic disorders.

Diabetes is a chronic metabolic disorder that impacts all age groups and affects a large population worldwide. Humans receive glucose from almost every food source, and after absorption from the gut, it reaches the liver, which functions as the distribution center for it. The insulin-responsive glucose transporter type 4 (GLUT-4) is a major carrier of glucose to the various cells (majorly expressed in myocytes, adipocytes, and cardiomyocytes) in a well-fed state. In fasting periods, the glucose supply is maintained by glycogenolysis and gluconeogenesis. In diabetes, the distribution of glucose is hampered due to several reasons. Furthermore, to treat this disorder, several drugs have been synthesized, and click chemistry plays an important role. A more recent concept for producing pharmaceuticals with a click chemistry approach makes any reaction more practical and stereospecific, along with a higher yield of products and a smaller number of by-products. This approach comprises a compiled study of the activity of numerous compelling antidiabetic drugs containing 1,2,3-triazole derivatives supported by click chemistry. In this review, we discuss the synthetic antidiabetic drugs made via click chemistry and their commendable role in improving diabetes care.

Middle East respiratory syndrome coronavirus (MERS-CoV) infects respiratory epithelial cells in humans and camels by binding to dipeptidyl peptidase 4 (DPP4) as its entry receptor. DPP4 is a multifunctional type II membrane protein with a long ectodomain and a short six-amino-acid (aa) cytoplasmic tail. MERS-CoV is known to bind to the ectodomain of DPP4 to gain entry into the host cell. However, the role of the cytoplasmic tail in the entry process remains unclear. Here, we show that mutating or deleting individual aa residues or the entire cytoplasmic tail of DPP4 (ΔcytDPP4) does not completely prevent DPP4 from being inserted into the membrane or from allowing the binding of the MERS-CoV spike protein and pseudovirus infection. Although two mutants, ΔcytDPP4, and a single aa deleted DPP4 (ΔK6DPP4) displayed less surface presentation than wtDPP4, the spike protein could still bind and localize on different DPP4 mutants. The reduced surface expression of ΔK6DPP4 might be due to the extended transmembrane domain, which is altered by the hydrophobic tryptophan (W) residue adjacent to the deleted K6. Furthermore, HEK293T cells transiently expressing DPP4 mutants were permeable to MERS-CoV pseudovirus infection. Not only transiently expressing cells but also cells stably expressing the ΔcytDPP4 mutant were susceptible to MERS-CoV pseudoviral infection, indicating that the DPP4 cytoplasmic tail is not required for MERS-CoV entry. Overall, these data suggest that, although MERS-CoV binds to DPP4, other host factors may need to interact with DPP4 or the spike protein to trigger internalization.

As an incretin hormone, Glucagon-like peptide-1 (GLP-1) has obvious effects on blood glucose regulation and weight loss. GLP-1 receptor (GLP-1R) agonists are synthetic products that have similar effects to GLP-1 but are less prone to degradation, and they are widely used in the treatment of type 2 diabetes and obesity. In recent years, different beneficial effects of GLP-1R agonists were discovered, such as reducing ischemia-reperfusion injury, improving the function of various organs, alleviating substance use disorder, affecting tumorigenesis, regulating bone metabolism, changing gut microbiota composition, and prolonging graft survival. Therefore, GLP-1R agonists have great potential for clinical application in various diseases. Here, we briefly summarized the beneficial effects of GLP-1R agonists other than the anti-diabetic and anti-obesity effects.

The mechanisms of ductus arteriosus (DA) closure involve vasoconstriction and vascular remodeling. Previous findings indicate that the glucagon-like peptide-1 receptor agonist (GLP-1RA) exhibits antihypertensive and anti-remodeling effects in the pulmonary circulation. However, its role in the DA remains unknown. This study aimed to investigate whether exendin-4 (Ex-4), a GLP-1RA, can regulate DA patency and elucidate its mechanisms. After confirming the presence of GLP-1R in neonatal rat DA tissue in vivo, the effects of Ex-4 on DA patency in neonatal rats were sequentially examined. Two hours after birth, we observed spontaneous closure of the DA in control rats. In contrast, Ex-4 prevented the closure of DA, accompanied by reduced intimal thickening. Ex-4 attenuated oxygen-induced vasoconstriction in isolated DA rings ex vivo. This effect was diminished in the presence of H89, a PKA inhibitor. In vitro, Ex-4 inhibited platelet-derived growth factor (PDGF)-BB-induced proliferation and migration of DA smooth muscle cells. Additionally, Ex-4 inhibited PDGF-BB-induced reactive oxygen species (ROS) production, calcium mobilization, and signal transduction of MAPK and Akt pathways. Furthermore, Ex-4 preserved the nuclear expression of Nrf2 attenuated by PDGF-BB. Similarly, all these in vitro effects of Ex-4 were blunted by H89. In conclusion, Ex-4 maintains postnatal DA patency through vasodilatation and anti-remodeling via the PKA pathway. The GLP-1R/PKA pathway emerges as a promising target of DA patency in clinical management.

Substrate specificity determines protease functions in physiology and in clinical and biotechnological applications, yet quantitative cleavage information is often unavailable, biased, or limited to a small number of events. Here, we develop qPISA (quantitative Protease specificity Inference from Substrate Analysis) to study Dipeptidyl Peptidase Four (DPP4), a key regulator of blood glucose levels. We use mass spectrometry to quantify >40,000 peptides from a complex, commercially available peptide mixture. By analyzing changes in substrate levels quantitatively instead of focusing on qualitative product identification through a binary classifier, we can reveal cooperative interactions within DPP4's active pocket and derive a sequence motif that predicts activity quantitatively. qPISA distinguishes DPP4 from the related C. elegans DPF-3 (a DPP8/9-orthologue), and we relate the differences to the structural features of the two enzymes. We demonstrate that qPISA can direct protein engineering efforts like the stabilization of GLP-1, a key DPP4 substrate used in the treatment of diabetes and obesity. Thus, qPISA offers a versatile approach for profiling protease and especially exopeptidase specificity, facilitating insight into enzyme mechanisms and biotechnological and clinical applications.

The age-related decline in appetite and food intake - termed "anorexia of ageing" - is implicated in undernutrition in later life and hence provides a public health challenge for our ageing population. Eating behaviour is controlled, in part, by homeostatic mechanisms which sense nutrient status and provide feedback to appetite control regions of the brain. Such feedback signals, propagated by episodic gut hormones, are dysregulated in some older adults. The secretory responses of appetite-related gut hormones to feeding are amplified, inducing a more anorexigenic signal which is associated with reduced appetite and food intake. Such an augmented response would indicate an increase in gut sensitivity to nutrients. Consequently, this review explores the role of gastrointestinal tract nutrient sensing in age-related appetite dysregulation. We review and synthesise evidence for age-related alterations in nutrient sensing which may explain the observed hormonal dysregulation. Drawing on what is known regarding elements of nutrient sensing pathways in animal models, in other tissues of the body, and in certain models of disease, we identify potential causal mechanisms including alterations in enteroendocrine cell number and distribution, dysregulation of cell signalling pathways, and changes in the gut milieu. From identified gaps in evidence, we highlight interesting and important avenues for future research.

Dipeptidyl peptidase 9 (DPP9) is an intracellular amino-dipeptidase with physiological roles in the immune system, DNA repair and mitochondria homeostasis, while its deregulation is linked to cancer progression and immune-associated defects. Through its rare ability to cleave a peptide bond following the imino-acid proline, DPP9 acts as a molecular switch that regulates key proteins, such as the tumor-suppressor BRCA2. In this review we will discuss key concepts underlying the outcomes of protein processing by DPP9, including substrate turn-over by the N-degron pathway. Additionally, we will review non-enzymatic roles and the regulation of DPP9 by discussing the interactome of this protease, which includes SUMO1, Filamin A, NLRP1 and CARD8.

Diet and lifestyle modifications remain the foundation of obesity treatment, but they have historically proven insufficient for significant, long-term weight loss. As a result, there is a high demand for new pharmacologic treatments to promote weight loss and prevent life-threatening diseases associated with obesity. Researchers are particularly interested in 1 type of drug, glucagon-like peptide 1 receptor agonists (GLP-1 RAs), because of its promising potential in addressing the limitations of non-pharmacologic treatments. In addition to their role in weight loss, these drugs have shown promising early evidence of cardiovascular benefits in obese patients, further enhancing their clinical relevance. Semaglutide and liraglutide, which were initially approved for the treatment of type 2 diabetes, have since been approved by the Food and Drug Administration as weight loss medications due to their effectiveness in promoting significant and sustained weight loss. In this narrative review, we will explore the mechanism of GLP-1 RAs, their effects on weight loss, cardiovascular risk factors and outcomes, common adverse effects, and strategies for managing these effects.

We present our efforts in computational drug design against dipeptidyl peptidase 4 (DPP4), DPP8 and DPP9. We applied cosolvent molecular dynamics (MD) simulations to these three protein targets of interest. Our primary motivation is the growing interest in DPP8 and DPP9 as emerging drug targets. Due to the high similarity between DPP4, DPP8 and DPP9, DPP4 was also included in these analyses. The cosolvent molecular dynamics simulations reproduce key ligand binding features and known binding pockets, while also highlighting interesting fragment positions for future ligand optimization. The resulting fragment maps from the cosolvent molecular dynamics are freely available for use in future research (https://github.com/UAMC-Olivier/DPP489_cosolvent_MD/). Detailed instructions for easy visualization of the fragment maps are provided, ensuring that the results are usable by both computational and medicinal chemists. Additionally, we used the fragment maps to search for the binding pockets with significant potential using an algorithmic approach combining top fragment locations. To discover novel binding scaffolds, a limited pharmacophore screening was performed, where the pharmacophores were based on the analyses of the cosolvent simulations. Unfortunately, inhibitory potencies were in the higher micromolar range, but we optimized the resulting scaffolds in silico using relative binding free energy calculations for future inhibitor design and synthesis.

Incretin hormones potentiate the glucose-induced insulin secretion following enteral nutrient intake. The best characterised incretin hormones are glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) which are produced in and secreted from the gut in response to nutrient ingestion. The property of incretins to enhance endogenous insulin secretion only at elevated blood glucose levels makes them interesting therapeutics for type 2 diabetes mellitus with a better safety profile than exogenous insulin. While incretin therapeutics (especially GLP-1 agonists, and more recently also GLP-1 / GIP dual agonists and other drugs that influence the incretin metabolism (e.g., dipeptidyl peptidase-4 (DPP-4) inhibitors)) are already widely used treatment options for human type 2 diabetes, these drugs are not yet approved for the therapy of feline diabetes mellitus. This review provides an introduction to incretins and feline diabetes mellitus in general and summarises the current study situation on incretins as therapeutics for feline diabetes mellitus to assess their possible future potential in feline medicine. Studies to date on the use of GLP-1 receptor agonists (GLP-1RA) in healthy cats largely confirm their insulinotropic effect known from other species. In diabetic cats, GLP-1RAs appear to significantly reduce glycaemic variability (GV, an indicator for the quality of glycaemic control), which is important for the management of the disease and prevention of long-term complications. However, for widespread use in feline diabetes mellitus, further studies are required that include larger numbers of diabetic cats, and that consider and test a possible need for dose adjustments to overweight and diabetic cats. Also evaluation of the outcome of GLP-1RA monotherapy will be neceessary.

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.

Obesity and type 2 diabetes mellitus (T2DM) are widespread, non-communicable diseases that are responsible for considerable levels of morbidity and mortality globally, primarily in the form of cardiovascular disease (CVD). Changes to lifestyle and behaviour have insufficient long-term efficacy in most patients with these diseases; metabolic surgery, although effective, is not practically deliverable on the scale that is required. Over the past two decades, therapies based on incretin hormones, spearheaded by glucagon-like peptide 1 (GLP1) receptor agonists (GLP1RAs), have become the treatment of choice for obesity and T2DM, and clinical evidence now suggests that these agents have benefits for CVD. We review the latest advances in incretin-based pharmacotherapy. These include 'GLP1 plus' agents, which combine the known advantages of GLP1RAs with the activity of additional hormones, such as glucose-dependent insulinotropic peptide, glucagon and amylin, to achieve desired therapeutic goals. Second-generation non-peptidic oral GLP1RAs promise to extend the benefits of GLP1 therapy to those who do not want, or cannot have, subcutaneous injection therapy. We conclude with a discussion of the knowledge gaps that must be addressed before incretin-based therapies can be properly deployed for maximum benefit in the treatment of obesity and T2DM.

For more than a century, physicians have searched for ways to pharmacologically reduce excess body fat. The tide has finally turned with recent advances in biochemically engineered agonists for the receptor of glucagon-like peptide-1 (GLP-1) and their use in GLP-1-based polyagonists. These polyagonists reduce body weight through complementary pharmacology by incorporating the receptors for glucagon and/or the glucose-dependent insulinotropic polypeptide (GIP). In their most advanced forms, gut-hormone polyagonists achieve an unprecedented weight reduction of up to ∼20%-30%, offering a pharmacological alternative to bariatric surgery. Along with favorable effects on glycemia, fatty liver, and kidney disease, they also offer beneficial effects on the cardiovascular system and adipose tissue. These new interventions, therefore, hold great promise for the future of anti-obesity medications.

Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are two incretins that bind to their respective receptors and activate the downstream signaling in various tissues and organs. Both GIP and GLP-1 play roles in regulating food intake by stimulating neurons in the brain's satiety center. They also stimulate insulin secretion in pancreatic β-cells, but their effects on glucagon production in pancreatic α-cells differ, with GIP having a glucagonotropic effect during hypoglycemia and GLP-1 exhibiting glucagonostatic effect during hyperglycemia. Additionally, GIP directly stimulates lipogenesis, while GLP-1 indirectly promotes lipolysis, collectively maintaining healthy adipocytes, reducing ectopic fat distribution, and increasing the production and secretion of adiponectin from adipocytes. Together, these two incretins contribute to metabolic homeostasis, preventing both hyperglycemia and hypoglycemia, mitigating dyslipidemia, and reducing the risk of cardiovascular diseases in individuals with type 2 diabetes and obesity. Several GLP-1 and dual GIP/GLP-1 receptor agonists have been developed to harness these pharmacological effects in the treatment of type 2 diabetes, with some demonstrating robust effectiveness in weight management and prevention of cardiovascular diseases. Elucidating the underlying cellular and molecular mechanisms could potentially usher in the development of new generations of incretin mimetics with enhanced efficacy and fewer adverse effects. The treatment guidelines are evolving based on clinical trial outcomes, shaping the management of metabolic and cardiovascular diseases.

Plant extracts are increasingly recognized for their potential in modulating (postprandial) blood glucose levels. In this context, root extracts are of particular interest due to their high concentrations and often unique spectrum of plant bioactives. To identify new plant species with potential glucose-lowering activity, simple and robust methodologies are often required. For this narrative review, literature was sourced from scientific databases (primarily PubMed) in the period from June 2022 to January 2024. The regulatory targets of glucose homeostasis that could be modulated by bioactive plant compounds were used as search terms, either alone or in combination with the keyword "root extract". As a result, we present a comprehensive methodological toolbox for studying the glucose homeostasis modulating properties of plant extracts and its constituents. The described assays encompass in-vitro investigations involving enzyme inhibition (α-amylase, α-glucosidase, dipeptidyl peptidase 4), assessment of sodium-dependent glucose transporter 1 activity, and evaluation of glucose transporter 4 translocation. Furthermore, we describe a patch-clamp technique to assess the impact of extracts on KATP channels. While validating in-vitro findings in living organisms is imperative, we introduce two screenable in-vivo models (the hen's egg test and Drosophila melanogaster). Given that evaluation of the bioactivity of plant extracts in rodents and humans represents the current gold standard, we include approaches addressing this aspect. In summary, this review offers a systematic guide for screening plant extracts regarding their influence on key regulatory elements of glucose homeostasis, culminating in the assessment of their potential efficacy in-vivo. Moreover, application of the presented toolbox might contribute to further close the knowledge gap on the precise mechanisms of action of plant-derived compounds.

Nutritional, endocrine, and neurological signals converge in multiple brain centres to control feeding behaviour and food intake as part of the allostatic regulation of energy balance. Among the several neuroendocrine systems involved, the leptin, glucocorticoid, and glucagon-like peptide 1 (GLP1) systems have been extensively researched. Leptin is at the top hierarchical level since its complete absence is sufficient to trigger severe hyperphagia. Glucocorticoids are key regulators of the energy balance adaptation to stress and their sustained excess leads to excessive adiposity and metabolic perturbations. GLP1 participates in metabolic adaptation to food intake, regulating insulin secretion and satiety by parallel central and peripheral signalling systems. Herein, we review the brain and peripheral targets of these three hormone systems that integrate to regulate food intake, feeding behaviour, and metabolic homeostasis. We examine the functional relationships between leptin, glucocorticoids, and GLP1 at the central and peripheral levels, including the cross-regulation of their circulating levels and their cooperative or antagonistic actions at different brain centres. The pathophysiological roles of these neuroendocrine systems in dysregulated intake are explored in the two extremes of body adiposity - obesity and lipodystrophy - and eating behaviour disorders.

The role of the gut microbiota and its interplay with host metabolic health, particularly in the context of type 2 diabetes mellitus (T2DM) management, is garnering increasing attention. Dipeptidyl peptidase 4 (DPP4) inhibitors, commonly known as gliptins, constitute a class of drugs extensively used in T2DM treatment. However, their potential interactions with gut microbiota remain poorly understood. In this study, we employed computational methodologies to investigate the binding affinities of various gliptins to DPP4-like homologs produced by intestinal bacteria. The 3D structures of DPP4 homologs from gut microbiota species, including Segatella copri, Phocaeicola vulgatus, Bacteroides uniformis, Parabacteroides merdae, and Alistipes sp., were predicted using computational modeling techniques. Subsequently, molecular dynamics simulations were conducted for 200 ns to ensure the stability of the predicted structures. Stable structures were then utilized to predict the binding interactions with known gliptins through molecular docking algorithms. Our results revealed binding similarities of gliptins toward bacterial DPP4 homologs compared to human DPP4. Specifically, certain gliptins exhibited similar binding scores to bacterial DPP4 homologs as they did with human DPP4, suggesting a potential interaction of these drugs with gut microbiota. These findings could help in understanding the interplay between gliptins and gut microbiota DPP4 homologs, considering the intricate relationship between the host metabolism and microbial communities in the gut.

Glucagon-like peptide receptor (GLP-1R) agonists (e.g., semaglutide, liraglutide, etc.) are efficient treatment options for people with type 2 diabetes and obesity. The manufacturing method to produce semaglutide, a blockbuster GLP-1 drug on the market, involves multistep synthesis. The large peptide has a hydrophobic fatty acid side chain that makes it sparingly soluble, and its handling, purification, and large-scale production difficult. The growing demand for semaglutide that the manufacturer is not capable of addressing immediately triggered a worldwide shortage. Thus, we have developed a potential alternative analogue to semaglutide by replacing the hydrophobic fatty acid with a hydrophilic human complex-type biantennary oligosaccharide. Our novel glycoGLP-1 analogue was isolated in an ∼10-fold higher yield compared with semaglutide. Importantly, our glycoGLP-1 analogue possessed a similar GLP-1R activation potency to semaglutide and was biologically active in vivo in reducing glucose levels to a similar degree as semaglutide.

Obesity is one of the critical public health problems in our society. It leads to various health conditions, such as type 2 diabetes mellitus, cardiovascular disease, hypertension, dyslipidaemia, and non-alcoholic fatty liver disease. With the rising incidence of obesity, there is a growing demand for new therapies which can effectively manage body weight and improve health.

Currently under development, multi-receptor agonist drugs may offer a promising solution to meet this unmet medical need. Retatrutide is a novel triple receptor agonist peptide that targets the glucagon receptor (GCGR), glucose-dependent insulinotropic polypeptide receptor (GIPR), and glucagon-like peptide-1 receptor (GLP-1R). This novel drug has the potential to treat metabolic abnormalities associated with obesity as well as diseases resulting from it due to its distinct mechanism of action. The Phase III trial of this pipeline drug for treating type 2 diabetes mellitus, non-alcoholic fatty liver disease, and obesity started on August 28, 2023. The results of a Phase II clinical trial have demonstrated significant weight reduction in overweight and obese adults. Specifically, the trial reported an average weight loss of 17.5% and 24.4% at 24 and 48 weeks, respectively.

These findings hold promise for the development of effective weight loss interventions in this population group. There is a need for more phase III studies to provide sufficient clinical evidence for the effectiveness of retatrutide, as current evidence is limited to phase II studies and has yet to prove its worth in a larger population. Here, we aimed to provide an overview of retatrutide's safety and effectiveness in treating obesity.

Dipeptidyl peptidase 4 (DPP-4) and neprilysin (NEP) rapidly degrade glucagon-like peptide 1 (GLP-1) in mice. Commercially available sandwich ELISA kits may not accurately detect the degradation products, leading to potentially misleading results. We aimed to stabilize GLP-1 in mice, allowing reliable measurement with sensitive commercially available ELISA kits. Nonanesthetized male C57Bl/6JRj mice were subjected to an oral glucose tolerance test (OGTT; 2 g/kg glucose), and plasma total and intact GLP-1 were measured (Mercodia and Alpco ELISA kits, respectively). No GLP-1 increases were seen in samples taken beyond 15 min after the glucose load. Samples taken at 5 and 10 min after the OGTT showed a minor increase in total, but not intact, GLP-1. We then administered saline (control), or a DPP-4 inhibitor (valine pyrrolidide or sitagliptin) with or without an NEP-inhibitor (sacubitril), 30 min before the OGTT. In the inhibitor groups only, intact GLP-1 increased significantly during the OGTT. After injecting male C57Bl/6JRj mice with a known dose of GLP-1(7-36)NH2, peak GLP-1 levels were barely detectable after saline but were 5- to 10-fold higher during sitagliptin and the combination of sitagliptin/sacubitril. The half-life of the GLP-1 plasma disappearance increased up to sevenfold during inhibitor treatment. We conclude that reliable measurement of GLP-1 secretion is not possible in mice in vivo with commercially available sandwich ELISA kits, unless degradation is prevented by inhibition of DPP-4 and perhaps NEP. The described approach allows improved estimates of GLP-1 secretion for future studies, although it is a limitation that these inhibitors additionally influence levels of insulin and glucagon.

The prevalence of obesity continues to rise in both adolescents and adults, in parallel obesity is strongly associated with the increased incidence of type 2 diabetes, heart failure, certain types of cancer, and all-cause mortality. In relation to obesity, many pharmacological approaches of the past have tried and failed to combat the rising obesity epidemic, particularly due to insufficient efficacy or unacceptable side effects. However, while the history of antiobesity medication is plagued by failures and disappointments, we have witnessed over the last 10 years substantial progress, particularly in regard to biochemically optimized agonists at the receptor for glucagon-like peptide-1 (GLP-1R) and unimolecular coagonists at the receptors for GLP-1 and the glucose-dependent insulinotropic polypeptide (GIP). Although the GIP receptor:GLP-1R coagonists are being heralded as premier pharmacological tools for the treatment of obesity and diabetes, uncertainty remains as to why these drugs testify superiority over best-in-class GLP-1R monoagonists. Particularly with regard to GIP, there remains great uncertainty if and how GIP acts on systems metabolism and if the GIP system should be activated or inhibited to improve metabolic outcome in adjunct to GLP-1R agonism. In this review, we summarize recent advances in GLP-1- and GIP-based pharmacology and discuss recent findings and open questions related to how the GIP system affects systemic energy and glucose metabolism.

The discovery of long-acting incretin receptor agonists represents a major stride forward in tackling the dual epidemic of obesity and diabetes. Here we outline the evolution of incretin-based pharmacotherapy, from exendin-4 to the discovery of the multi-incretin hormone receptor agonists that look set to be our next step toward curing diabetes and obesity. We discuss the multiagonists currently in clinical trials and the improvement in efficacy each new generation of these drugs bring. The success of these agents in preclinical models and clinical trials suggests a promising future for multiagonists in the treatment of metabolic diseases, with the most recent glucose-dependent insulinotropic peptide receptor:glucagon-like peptide 1 receptor:glucagon receptor (GIPR:GLP-1R:GCGR) triagonists rivaling the efficacy of bariatric surgery. However, further research is needed to fully understand how these therapies exert their effect on body weight and in the last section we cover open questions about the potential mechanisms of multiagonist drugs, and the understanding of how gut-brain communication can be leveraged to achieve sustained body weight loss without adverse effects.

Bone is a highly dynamic organ that changes with the daily circadian rhythm. During the day, bone resorption is suppressed due to eating, while it increases at night. This circadian rhythm of the skeleton is regulated by gut hormones. Until now, gut hormones that have been found to affect skeletal homeostasis include glucagon-like peptide-1 (GLP-1), glucagon-like peptide-2 (GLP-2), glucose-dependent insulinotropic polypeptide (GIP), and peptide YY (PYY), which exerts its effects by binding to its cognate receptors (GLP-1R, GLP-2R, GIPR, and Y1R). Several studies have shown that GLP-1, GLP-2, and GIP all inhibit bone resorption, while GIP also promotes bone formation. Notably, PYY has a strong bone resorption-promoting effect. In addition, gut microbiota (GM) plays an important role in maintaining bone homeostasis. This review outlines the roles of GLP-1, GLP-2, GIP, and PYY in bone metabolism and discusses the roles of gut hormones and the GM in regulating bone homeostasis and their potential mechanisms.

Glucagon like peptide-1 (GLP-1) is a peptide hormone encoded by the pre-proglucagon gene that serves multiple physiological functions, including incretin action. While GLP-1 is primarily synthesized in the L cells of the lower intestine, recent findings indicate its presence in the stomachs of both rats and humans. However, the role of gastric GLP-1 in other species remains unclear. In this study, we aimed to identify GLP-1-producing cells and examine the localization of GLP-1 production in the mouse stomach. We found that pre-proglucagon mRNA was higher in the corpus than that in the antrum of the stomach. In addition, GLP-1 immunoreactive cells were found in the gastric mucosa, and their cell number was higher in the corpus than that in the antrum. Double immunofluorescence showed that some GLP-1 immunoreactive cells displayed somatostatin immunoreactivity, whereas did not co-localize with ghrelin and gastrin. Moreover, transmembrane G protein-coupled Receptor 5 (TGR5) agonist decreased pre-proglucagon mRNA expression in SG-1 cells in a concentration-dependent manner, and in vivo experiments showed a decrease in its mRNA levels in the gastric corpus but not in the antrum. This study marks the first report of GLP-1 production in the mouse stomach. Our findings suggest that gastric pre-proglucagon mRNA expression is regulated by a distinct mechanism compared to the L cells of the lower intestine.

Glucagon-like peptide-1 (GLP-1) agonists are very popular and useful medications for the treatment of type 2 diabetes mellitus and obesity. Potent gastric emptying delay is common with these medications, serving as a major contributor to the postprandial glycemic control and weight loss benefits of these medications. Recently, multiple case reports and studies indicating safety risks for these medications and their use in patients planning to undergo general anesthesia have been published, as retained gastric contents can lead to intraoperative aspiration. New guidelines for these medications have been released to guide clinical practice for anesthesiologists. Some degree of preoperative cessation of these medications is required. At this time, the ideal window for cessation of these medications to optimize clinical efficacy while reducing aspiration risks has not yet been well elaborated on. Aspiration of gastric contents can still occur despite appropriate preoperative fasting in patients taking GLP-1 agonists. Gastric ultrasound appears to be an effective and objective way of preoperatively assessing a patient's stomach contents to make decisions regarding anesthetic management for patients prescribed these medications. This practice is limited by a general lack of training and implementation in current anesthesiology practice.

Metabolic dysfunction-associated fatty liver disease (MAFLD) has reached epidemic proportions globally in parallel to the rising prevalence of obesity. Despite its significant burden, there is no approved pharmacotherapy specifically tailored for this disease. Many potential drug candidates for MAFLD have encountered setbacks in clinical trials, due to safety concerns or/and insufficient therapeutic efficacy. Nonetheless, several investigational drugs that mimic the actions of endogenous metabolic hormones, including thyroid hormone receptor β (THRβ) agonists, fibroblast growth factor 21 (FGF21) analogues, and glucagon-like peptide-1 receptor agonists (GLP-1RAs), showed promising therapeutic efficacy and excellent safety profiles. Among them, resmetirom, a liver-targeted THRβ-selective agonist, has met the primary outcomes in alleviation of metabolic dysfunction-associated steatohepatitis (MASH), the advanced form of MAFLD, and liver fibrosis in phase-3 clinical trials. These hormone-based pharmacotherapies not only exhibit varied degrees of therapeutic efficacy in mitigating hepatic steatosis, inflammation and fibrosis, but also improve metabolic profiles. Furthermore, these three hormonal agonists/analogues act in a complementary manner to exert their pharmacological effects, suggesting their combined therapies may yield synergistic therapeutic benefits. Further in-depth studies on the intricate interplay among these metabolic hormones are imperative for the development of more efficacious combination therapies, enabling precision management of MAFLD and its associated comorbidities.

We assessed the effect of the prandial state on the pharmacokinetics, safety, and tolerability of single and multiple doses of orforglipron (LY3502970), an oral, non-peptide glucagon-like peptide 1 receptor agonist (GLP-1 RA), in two studies (A and B).

Study A and study B were phase 1, randomized, crossover studies in healthy adults aged 18-65 years and 21-70 years, respectively. Participants received single (3 mg, study A) or multiple (16 mg, study B) oral doses of orforglipron under fasted and fed conditions. Blood samples were collected pre- and postdose to assess area under the concentration-time curve (AUC), maximum observed drug concentration (Cmax), time of Cmax (tmax), and half-life (t1/2) associated with terminal rate constant. AUC and Cmax were analyzed using a linear mixed-effects model. Treatment differences were presented as ratios of geometric least squares means (GLSM). Treatment-emergent adverse events (TEAEs), adverse events of special interest, and serious adverse events were assessed.

Study A included 12 participants (mean age 45.0 years; male 66.7%); study B included 34 participants (mean age 42.8 years; male 88.2%). GLSM AUC and Cmax were lower by 23.7% and 23.2% in study A, and 17.6% and 20.9% in study B, in the fed versus fasted states, respectively. In both studies, t1/2 and median tmax were comparable between fed and fasted states. The majority of TEAEs in both studies were gastrointestinal tract-related conditions. No serious adverse events or deaths were reported in either study.

The observed pharmacokinetic differences due to the prandial state are unlikely to contribute to clinically meaningful differences in the efficacy of orforglipron. The safety profile was consistent with the known profiles of other GLP-1 RAs. Given the absence of prandial restrictions, orforglipron may emerge as a convenient oral treatment option for patients with type 2 diabetes or obesity.

ClinicalTrials.gov identifiers, NCT03929744 and NCT05110794.

Currently, noninvasive imaging techniques and circulating biomarkers are still insufficient to accurately assess carotid plaque stability, and an in-depth understanding of the molecular mechanisms that contribute to plaque instability is still lacking.

We established a clinical study cohort containing 182 patients with carotid artery stenosis. After screening, 39 stable and 49 unstable plaques were included in the discovery group, and quantitative proteomics analysis based on data independent acquisition was performed for these plaque samples. Additionally, 35 plaques were included in the validation group to validate the proteomics results by immunohistochemistry analysis.

A total of 397 differentially expressed proteins were identified in stable and unstable plaques. These proteins are primarily involved in ferroptosis and lipid metabolism-related functions and pathways. Plaque validation results showed that ferroptosis- and lipid metabolism-related proteins had different expression trends in stable plaques versus unstable fibrous cap regions and lipid core regions. Ferroptosis- and lipid metabolism-related mechanisms in plaque stability were discussed.

Our results may provide a valuable strategy for revealing the mechanisms affecting plaque stability and will facilitate the discovery of specific biomarkers to broaden the therapeutic scope.

'Globesity' is a foremost challenge to the healthcare system. The limited efficacy and adverse effects of available oral pharmacotherapies pose a significant obstacle in the fight against obesity. The biology of the leading incretin hormone glucagon-like-peptide-1 (GLP-1) has been highly captivated during the last decade owing to its multisystemic pleiotropic clinical outcomes beyond inherent glucoregulatory action. That fostered a pharmaceutical interest in synthetic GLP-1 analogues to tackle type-2 diabetes (T2D), obesity and related complications. Besides, mechanistic insights on metabolic surgeries allude to an incretin-based hormonal combination strategy for weight loss that emerged as a forerunner for the discovery of injectable 'unimolecular poly-incretin-agonist' therapies. Physiologically, intestinal enteroendocrine L-cells (EECs) are the prominent endogenous source of GLP-1 peptide. Despite comprehending the potential of various G protein-coupled receptors (GPCRs) to stimulate endogenous GLP-1 secretion, decades of translational GPCR research have failed to yield regulatory-approved endogenous GLP-1 secretagogue oral therapy. Lately, a dual/poly-GPCR agonism strategy has emerged as an alternative approach to the traditional mono-GPCR concept. This review aims to gain a comprehensive understanding by revisiting the pharmacology of a few potential GPCR-based complementary avenues that have drawn attention to the design of orally active poly-GPCR agonist therapy. The merits, challenges and recent developments that may aid future poly-GPCR drug discovery are critically discussed. Subsequently, we project the mechanism-based therapeutic potential and limitations of oral poly-GPCR agonism strategy to augment intestinal GLP-1 for weight loss. We further extend our discussion to compare the poly-GPCR agonism approach over invasive surgical and injectable GLP-1-based regimens currently in clinical practice for obesity.

Glucose-insulinotropic polypeptide (GIP) is an incretin hormone that induces insulin secretion and decreases blood glucose levels. In addition, it has been reported to suppress osteoclast formation. Native GIP is rapidly degraded by dipeptidyl peptidase-4 (DPP-4). (D-Ala2)GIP is a newly developed GIP analog that demonstrates enhanced resistance to DPP-4. This study aimed to evaluate the influence of (D-Ala2)GIP on osteoclast formation and bone resorption during lipopolysaccharide (LPS)-induced inflammation in vivo and in vitro. In vivo, mice received supracalvarial injections of LPS with or without (D-Ala2)GIP for 5 days. Osteoclast formation and bone resorption were evaluated, and TNF-α and RANKL expression were measured. In vitro, the influence of (D-Ala2)GIP on RANKL- and TNF-α-induced osteoclastogenesis, LPS-triggered TNF-α expression in macrophages, and RANKL expression in osteoblasts were examined. Compared to the LPS-only group, calvariae co-administered LPS and (D-Ala2)GIP led to less osteoclast formation, lower bone resorption, and decreased TNF-α and RANKL expression. (D-Ala2)GIP inhibited osteoclastogenesis induced by RANKL and TNF-α and downregulated TNF-α expression in macrophages and RANKL expression in osteoblasts in vitro. Furthermore, (D-Ala2)GIP suppressed the MAPK signaling pathway. The results suggest that (D-Ala2)GIP dampened LPS-triggered osteoclast formation and bone resorption in vivo by reducing TNF-α and RANKL expression and directly inhibiting osteoclastogenesis.