Dietary salt promotes cognition impairment through GLP-1R/mTOR/p70S6K signaling pathway.

Dietary salt has been associated with cognitive impairment in mice, possibly related to damaged synapses and tau hyperphosphorylation. However, the mechanism underlying how dietary salt causes cognitive dysfunction remains unclear. In our study, either a high-salt (8%) or normal diet (0.5%) was used to feed C57BL/6 mice for three months, and N2a cells were cultured in normal medium, NaCl medium (80 mM), or NaCl (80 mM) + Liraglutide (200 nM) medium for 48 h. Cognitive function in mice was assessed using the Morris water maze and shuttle box test, while anxiety was evaluated by the open field test (OPT). Western blotting (WB), immunofluorescence, and immunohistochemistry were utilized to assess the level of Glucagon-like Peptide-1 receptor (GLP-1R) and mTOR/p70S6K pathway. Electron microscope and western blotting were used to evaluate synapse function and tau phosphorylation. Our findings revealed that a high salt diet (HSD) reduced the level of synaptophysin (SYP) and postsynaptic density 95 (PSD95), resulting in significant synaptic damage. Additionally, hyperphosphorylation of tau at different sites was detected. The C57BL/6 mice showed significant impairment in learning and memory function compared to the control group, but HSD did not cause anxiety in the mice. In addition, the level of GLP-1R and autophagy flux decreased in the HSD group, while the level of mTOR/p70S6K was upregulated. Furthermore, liraglutide reversed the autophagy inhibition of N2a treated with NaCl. In summary, our study demonstrates that dietary salt inhibits the GLP-1R/mTOR/p70S6K pathway to inhibit autophagy and induces synaptic dysfunction and tau hyperphosphorylation, eventually impairing cognitive dysfunction.

Protecting cardiomyocytes from hypoxia-reoxygenation injury, empaglifozin and liraglutide alone or in combination?

OBJECTIVES: Empagliflozin, a sodium-dependent glucose co-transporter 2 (SGLT2) inhibitor, and liraglutide, a GLP-1 receptor (GLP-1R) agonist, are commonly recognized for their cardiovascular benefits in individuals with type 2 diabetes (T2D). In prior studies, we have demonstrated that both drugs, alone or in combination, were able to protect cardiomyocytes from injury induced by diabetes. Mechanistic investigations also suggested that the cardioprotective effect may be independent of diabetes In this study, we utilized a hypoxia-reoxygenation (H/R) model to investigate the cardiovascular benefits of SGLT2 inhibitor empagliflozin and GLP-1 receptor (GLP-1R) agonist liraglutide, both alone and in combination, in the absence of T2D. Our hypothesis was that empagliflozin and liraglutide, either individually or in combination, would demonstrate cardioprotective properties against H/R-induced injury, with an additive and/or synergistic effect anticipated from combination therapy. METHODS: In this study, the cardiac muscle cell line, HL-1 cells, were treated with vehicle, empagliflozin, liraglutide, or a combination of the two drugs. The cells were then subjected to a hypoxia-reoxygenation (H/R) protocol, consisting of 1 h of hypoxia followed by 24 h of reoxygenation. The effects of the treatments on cytotoxicity, oxidative stress, endothelial nitric oxide synthase (eNOS) activity, phospho-protein kinase C (PKC) beta and phospho-eNOS (Thr495) expression were subsequently evaluated at the end of the treatments. RESULTS: We found that H/R increased cytotoxicity and reduces eNOS activity, empagliflozin, liraglutide or combination treatment attenuated some or all of these effects with the combination therapy showing the greatest improvement. CONCLUSIONS: Empagliflozin, liraglutide or combination of these two have cardioprotective effect regardless of diabetes. Cardioprotective effects of SGLT2 inhibitor and GLP-1R agonist is additive and synergistic.

The role of G protein-coupled receptor kinases in GLP-1R ß-arrestin recruitment and internalisation.

The glucagon-like peptide 1 receptor (GLP-1R) is a validated clinical target for the treatment of type 2 diabetes and obesity. Unlike most G protein-coupled receptors (GPCRs), the GLP-1R undergoes an atypical mode of internalisation that does not require ß-arrestins. While differences in GLP-1R trafficking and ß-arrestin recruitment have been observed between clinically used GLP-1R agonists, the role of G protein-coupled receptor kinases (GRKs) in affecting these pathways has not been comprehensively assessed. In this study, we quantified the contribution of GRKs to agonist-mediated GLP-1R internalisation and ß-arrestin recruitment profiles using cells where endogenous ß-arrestins, or non-visual GRKs were knocked out using CRISPR/Cas9 genome editing. Our results confirm the previously established atypical ß-arrestin-independent mode of GLP-1R internalisation and revealed that GLP-1R internalisation is dependent on the expression of GRKs. Interestingly, agonist-mediated GLP-1R ß-arrestin 1 and ß-arrestin 2 recruitment were differentially affected by endogenous GRK knockout with ß-arrestin 1 recruitment more sensitive to GRK knockout than ß-arrestin 2 recruitment. Moreover, individual overexpression of GRK2, GRK3, GRK5 or GRK6 in a newly generated GRK2/3/4/5/6 HEK293 cells, rescued agonist-mediated ß-arrestin 1 recruitment and internalisation profiles to similar levels, suggesting that there is no specific GRK isoform that drives these pathways. This study advances mechanistic understanding of agonist-mediated GLP-1R internalisation and provides novel insights into how GRKs may fine-tune GLP-1R signalling.

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

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

Restoration of blood vessel regeneration in the era of combination SGLT2i and GLP-1RA therapy for diabetes and obesity.

Ischaemic cardiovascular diseases, including peripheral and coronary artery disease, myocardial infarction, and stroke, remain major comorbidities for individuals with type 2 diabetes (T2D) and obesity. During cardiometabolic chronic disease (CMCD), hyperglycaemia and excess adiposity elevate oxidative stress and promote endothelial damage, alongside an imbalance in circulating pro-vascular progenitor cells that mediate vascular repair. Individuals with CMCD demonstrate pro-vascular 'regenerative cell exhaustion' (RCE) characterized by excess pro-inflammatory granulocyte precursor mobilization into the circulation, monocyte polarization towards pro-inflammatory vs. anti-inflammatory phenotype, and decreased pro-vascular progenitor cell content, impairing the capacity for vessel repair. Remarkably, targeted treatment with the sodium-glucose cotransporter-2 inhibitor (SGLT2i) empagliflozin in subjects with T2D and coronary artery disease, and gastric bypass surgery in subjects with severe obesity, has been shown to partially reverse these RCE phenotypes. SGLT2is and glucagon-like peptide-1 receptor agonists (GLP-1RAs) have reshaped the management of individuals with T2D and comorbid obesity. In addition to glucose-lowering action, both drug classes have been shown to induce weight loss and reduce mortality and adverse cardiovascular outcomes in landmark clinical trials. Furthermore, both drug families also act to reduce systemic oxidative stress through altered activity of overlapping oxidase and antioxidant pathways, providing a putative mechanism to augment circulating pro-vascular progenitor cell content. As SGLT2i and GLP-1RA combination therapies are emerging as a novel therapeutic opportunity for individuals with poorly controlled hyperglycaemia, potential additive effects in the reduction of oxidative stress may also enhance vascular repair and further reduce the ischaemic cardiovascular comorbidities associated with T2D and obesity.

Pharmacological Advances in Incretin-Based Polyagonism: What We Know and What We Don't.

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.

Brain access of incretins and incretin receptor agonists to their central targets relevant for appetite suppression and weight loss.

New incretin-based pharmacotherapies provide efficient and safe therapeutic options to curb appetite and produce weight loss in patients with obesity. Delivered systemically, these molecules produce pleiotropic metabolic benefits, but the target sites mediating their weight-suppressive action are located within the brain. Recent research has increased our understanding of the neural circuits and behavioral mechanisms involved in the anorectic and metabolic consequences of glucagon-like peptide 1 (GLP-1)-based weight loss strategies, yet little is known about how these drugs access their functional targets in the brain to produce sustained weight loss. The majority of brain cells expressing incretin receptors are located behind the blood-brain barrier, shielded from the circulation and fluctuations in the availability of peripheral signals, which is a major challenge for the development of CNS-targeted therapeutic peptides. GLP-1 receptor (GLP-1R) agonists with increased half-life and enhanced therapeutic benefit do not cross the blood-brain barrier, yet they manage to access discrete brain sites relevant to the regulation of energy homeostasis. In this review, we give a brief overview of the different routes for peptide hormones to access the brain. We then examine the evidence informing the routes employed by incretins and incretin receptor agonists to access brain targets relevant for their appetite and weight-suppressive actions. We highlight existing controversies and suggest future directions to further establish the functionally relevant access routes for GLP-1-based weight loss compounds, which might guide the development and selection of the future generation of incretin receptor polypharmacologies.

ER stress and unfolded protein response (UPR) signaling modulate GLP-1 receptor signaling in the pancreatic islets.

Insulin is essential for maintaining normoglycemia and is predominantly secreted in response to glucose stimulation by ß-cells. Incretin hormones, such as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide, also stimulate insulin secretion. However, as obesity and type 2 diabetes worsen, glucose-dependent insulinotropic polypeptide loses its insulinotropic efficacy, whereas GLP-1 receptor (GLP-1R) agonists continue to be effective owing to its signaling switch from Gs to Gq. Herein, we demonstrated that endoplasmic reticulum (ER) stress induced a transition from Gs to Gq in GLP-1R signaling in mouse islets. Intriguingly, chemical chaperones known to alleviate ER stress, such as 4-PBA and TUDCA, enforced GLP-1R's Gq utilization rather than reversing GLP-1R's signaling switch induced by ER stress or obese and diabetic conditions. In addition, the activation of X-box binding protein 1 (XBP1) or activating transcription factor 6 (ATF6), 2 key ER stress-associated signaling (unfolded protein response) factors, promoted Gs utilization in GLP-1R signaling, whereas Gq employment by ER stress was unaffected by XBP1 or ATF6 activation. Our study revealed that ER stress and its associated signaling events alter GLP-1R's signaling, which can be used in type 2 diabetes treatment.

A review of an investigational drug retatrutide, a novel triple agonist agent for the treatment of obesity.

BACKGROUND: 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. CURRENT EVIDENCE: 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. CONCLUSIONS: 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.

Glucagon-like peptide-1 receptor agonists and risk of major adverse liver outcomes in patients with chronic liver disease and type 2 diabetes.

OBJECTIVE: Phase II trials suggest glucagon-like peptide-1 receptor (GLP1) agonists resolve metabolic dysfunction-associated steatohepatitis but do not affect fibrosis regression. We aimed to determine the long-term causal effect of GLP1 agonists on the risk of major adverse liver outcomes (MALO) in patients with any chronic liver disease and type 2 diabetes. DESIGN: We used observational data from Swedish healthcare registers 2010-2020 to emulate a target trial of GLP1 agonists in eligible patients with chronic liver disease and type 2 diabetes. We used an inverse-probability weighted marginal structural model to compare parametric estimates of 10-year MALO risk (decompensated cirrhosis, hepatocellular carcinoma, liver transplantation or MALO-related death) in initiators of GLP1 agonists with non-initiators. We randomly sampled 5% of the non-initiators to increase computational efficiency. RESULTS: GLP1 agonist initiators had a 10-year risk of MALO at 13.3% (42/1026) vs 14.6% in non-initiators (1079/15 633) in intention-to-treat analysis (risk ratio (RR)=0.91, 95% CI=0.50 to 1.32). The corresponding 10-year per-protocol risk estimates were 7.4% (22/1026) and 14.4% (1079/15 633), respectively (RR=0.51, 95% CI=0.14 to 0.88). The per-protocol risk estimates at 6 years were 5.4% (21/1026) vs 9.0% (933/15 633) (RR=0.60, 95% CI=0.29 to 0.90) and at 8 years 7.2% (22/1026) vs 11.7% (1036/15 633) (RR=0.61, 95% CI=0.21 to 1.01). CONCLUSION: In patients with chronic liver disease and type 2 diabetes who adhered to therapy over time, GLP1 agonists may result in lower risk of MALO. This suggests that GLP1 agonists are promising agents to reduce risk of chronic liver disease progression in patients with concurrent type 2 diabetes, although this needs to be corroborated in randomised trials.

Semaglutide modulates prothrombotic and atherosclerotic mechanisms, associated with epicardial fat, neutrophils and endothelial cells network.

BACKGROUND: Obesity has increased in recent years with consequences on diabetes and other comorbidities. Thus, 1 out of 3 diabetic patients suffers cardiovascular disease (CVD). The network among glucose, immune system, endothelium and epicardial fat has an important role on pro-inflammatory and thrombotic mechanisms of atherogenesis. Since semaglutide, long-acting glucagon like peptide 1- receptor agonist (GLP-1-RA), a glucose-lowering drug, reduces body weight, we aimed to study its effects on human epicardial fat (EAT), aortic endothelial cells and neutrophils as atherogenesis involved-cardiovascular cells. METHODS: EAT and subcutaneous fat (SAT) were collected from patients undergoing cardiac surgery. Differential glucose consumption and protein cargo of fat-released exosomes, after semaglutide or/and insulin treatment were analyzed by enzymatic and TripleTOF, respectively. Human neutrophils phenotype and their adhesion to aortic endothelial cells (HAEC) or angiogenesis were analyzed by flow cytometry and functional fluorescence analysis. Immune cells and plasma protein markers were determined by flow cytometry and Luminex-multiplex on patients before and after 6 months treatment with semaglutide. RESULTS: GLP-1 receptor was expressed on fat and neutrophils. Differential exosomes-protein cargo was identified on EAT explants after semaglutide treatment. This drug increased secretion of gelsolin, antithrombotic protein, by EAT, modulated CD11b on neutrophils, its migration and endothelial adhesion, induced by adiposity protein, FABP4, or a chemoattractant. Monocytes and neutrophils phenotype and plasma adiposity, stretch, mesothelial, fibrotic, and inflammatory markers on patients underwent semaglutide treatment for 6 months showed a 20% reduction with statistical significance on FABP4 levels and an 80% increase of neutrophils-CD88. CONCLUSION: Semaglutide increases endocrine activity of epicardial fat with antithrombotic properties. Moreover, this drug modulates the pro-inflammatory and atherogenic profile induced by the adiposity marker, FABP4, which is also reduced in patients after semaglutide treatment.

Maternal GLP-1 receptor activation inhibits fetal growth.

Glucagon-like peptide 1 (GLP-1) regulates food intake, insulin production, and metabolism. Our recent study demonstrated that pancreatic α-cells-secreted (intraislet) GLP-1 effectively promotes maternal insulin secretion and metabolic adaptation during pregnancy. However, the role of circulating GLP-1 in maternal energy metabolism remains largely unknown. Our study aims to investigate systemic GLP-1 response to pregnancy and its regulatory effect on fetal growth. Using C57BL/6 mice, we observed a gradual decline in maternal blood GLP-1 concentrations. Subsequent administration of the GLP-1 receptor agonist semaglutide (Sem) to dams in late pregnancy revealed a modest decrease in maternal food intake during initial treatment. At the same time, no significant alterations were observed in maternal body weight or fat mass. Notably, Sem-treated dams exhibited a significant decrease in fetal body weight, which persisted even following the restoration of maternal blood glucose levels. Despite no observable change in placental weight, a marked reduction in the placenta labyrinth area from Sem-treated dams was evident. Our investigation further demonstrated a substantial decrease in the expression levels of various pivotal nutrient transporters within the placenta, including glucose transporter one and sodium-neutral amino acid transporter one, after Sem treatment. In addition, Sem injection led to a notable reduction in the capillary area, number, and surface densities within the labyrinth. These findings underscore the crucial role of modulating circulating GLP-1 levels in maternal adaptation, emphasizing the inhibitory effects of excessive GLP-1 receptor activation on both placental development and fetal growth.NEW & NOTEWORTHY Our study reveals a progressive decline in maternal blood glucagon-like peptide 1 (GLP-1) concentration. GLP-1 receptor agonist injection in late pregnancy significantly reduced fetal body weight, even after restoration of maternal blood glucose concentration. GLP-1 receptor activation significantly reduced the placental labyrinth area, expression of some nutrient transporters, and capillary development. Our study indicates that reducing maternal blood GLP-1 levels is a physiological adaptation process that benefits placental development and fetal growth.

Characterizing a new tool to manipulate area postrema GLP1R+ neurons across species.

Nausea is an uncomfortable sensation that accompanies many therapeutics, especially diabetes treatments involving glucagon-like peptide-1 receptor (GLP1R) agonists. Recent studies in mice have revealed that GLP1R-expressing neurons in the area postrema play critical roles in nausea. Here, we characterized a ligand-conjugated saporin that can efficiently ablate GLP1R+ cells from humans, mice, and the Suncus murinus, a small animal model capable of emesis. This new tool provides a strategy to manipulate specific neural pathways in the area postrema in the Suncus murinus and may help elucidate roles of area postrema GLP1R+ neurons in emesis during therapeutics involving GLP1R agonists.

Antibody blockade of activin type II receptors preserves skeletal muscle mass and enhances fat loss during GLP-1 receptor agonism.

OBJECTIVE: Glucagon-like peptide 1 (GLP-1) receptor agonists reduce food intake, producing remarkable weight loss in overweight and obese individuals. While much of this weight loss is fat mass, there is also a loss of lean mass, similar to other approaches that induce calorie deficit. Targeting signaling pathways that regulate skeletal muscle hypertrophy is a promising avenue to preserve lean mass and modulate body composition. Myostatin and Activin A are TGFß-like ligands that signal via the activin type II receptors (ActRII) to antagonize muscle growth. Pre-clinical and clinical studies demonstrate that ActRII blockade induces skeletal muscle hypertrophy and reduces fat mass. In this manuscript, we test the hypothesis that combined ActRII blockade and GLP-1 receptor agonism will preserve muscle mass, leading to improvements in skeletomuscular and metabolic function and enhanced fat loss. METHODS: In this study, we explore the therapeutic potential of bimagrumab, a monoclonal antibody against ActRII, to modify body composition alone and during weight loss induced by GLP-1 receptor agonist semaglutide in diet-induced obese mice. Mechanistically, we define the specific role of the anabolic kinase Akt in mediating the hypertrophic muscle effects of ActRII inhibition in vivo. RESULTS: Treatment of obese mice with bimagrumab induced a ∼10 % increase in lean mass while simultaneously decreasing fat mass. Daily treatment of obese mice with semaglutide potently decreased body weight; this included a significant decrease in both muscle and fat mass. Combination treatment with bimagrumab and semaglutide led to superior fat mass loss while simultaneously preserving lean mass despite reduced food intake. Treatment with both drugs was associated with improved metabolic outcomes, and increased lean mass was associated with improved exercise performance. Deletion of both Akt isoforms in skeletal muscle modestly reduced, but did not prevent, muscle hypertrophy driven by ActRII inhibition. CONCLUSIONS: Collectively, these data demonstrate that blockade of ActRII signaling improves body composition and metabolic parameters during calorie deficit driven by GLP-1 receptor agonism and demonstrate the existence of Akt-independent pathways supporting muscle hypertrophy in the absence of ActRII signaling.

The gut microbiota modulate locomotion via vagus-dependent glucagon-like peptide-1 signaling.

Locomotor activity is an innate behavior that can be triggered by gut-motivated conditions, such as appetite and metabolic condition. Various nutrient-sensing receptors distributed in the vagal terminal in the gut are crucial for signal transduction from the gut to the brain. The levels of gut hormones are closely associated with the colonization status of the gut microbiota, suggesting a complicated interaction among gut bacteria, gut hormones, and the brain. However, the detailed mechanism underlying gut microbiota-mediated endocrine signaling in the modulation of locomotion is still unclear. Herein, we show that broad-spectrum antibiotic cocktail (ABX)-treated mice displayed hypolocomotion and elevated levels of the gut hormone glucagon-like peptide-1 (GLP-1). Blockade of the GLP-1 receptor and subdiaphragmatic vagal transmission rescued the deficient locomotor phenotype in ABX-treated mice. Activation of the GLP-1 receptor and vagal projecting brain regions led to hypolocomotion. Finally, selective antibiotic treatment dramatically increased serum GLP-1 levels and decreased locomotion. Colonizing Lactobacillus reuteri and Bacteroides thetaiotaomicron in microbiota-deficient mice suppressed GLP-1 levels and restored the hypolocomotor phenotype. Our findings identify a mechanism by which specific gut microbes mediate host motor behavior via the enteroendocrine and vagal-dependent neural pathways.

Systemic inflammation from the brain.

The actions of glucagon-like peptide 1 receptor agonists in the CNS reduce systemic inflammation.

Leptin Reduction as a Required Component for Weight Loss.

Partial leptin reduction can induce significant weight loss, while weight loss contributes to partial leptin reduction. The cause-and-effect relationship between leptin reduction and weight loss remains to be further elucidated. Here, we show that FGF21 and the glucagon-like peptide 1 receptor (GLP-1R) agonist liraglutide rapidly induced a reduction in leptin. This leptin reduction contributed to the beneficial effects of GLP-1R agonism in metabolic health, as transgenically maintaining leptin levels during treatment partially curtailed the beneficial effects seen with these agonists. Moreover, a higher degree of leptin reduction during treatment, induced by including a leptin neutralizing antibody with either FGF21 or liraglutide, synergistically induced greater weight loss and better glucose tolerance in diet-induced obese mice. Furthermore, upon cessation of either liraglutide or FGF21 treatment, the expected immediate weight regain was observed, associated with a rapid increase in circulating leptin levels. Prevention of this leptin surge with leptin neutralizing antibodies slowed down weight gain and preserved better glucose tolerance. Mechanistically, a significant reduction in leptin induced a higher degree of leptin sensitivity in hypothalamic neurons. Our observations support a model that postulates that a reduction of leptin levels is a necessary prerequisite for substantial weight loss, and partial leptin reduction is a viable strategy to treat obesity and its associated insulin resistance.

Institutional experience on the impact of glucagon-like peptide-1 agonists (GLP-1) on glycemic control and weight loss in patients with type 2 diabetes at the Dubai Diabetes Center, United Arab Emirates.

AIMS: To describe the effect of three classes of GLP1 analogues on HbA1c and weight over one year in a homogenous group of patients at the Dubai Diabetes Center in Dubai, United Arab Emirates. The specific objectives are to study the extent of change in HbA1c and weight loss on these medications as well as the sustainability of change over one year. METHODS: A retrospective audit of patients diagnosed Type 2 diabetes receiving one of the three following GLP-1 agonists (Exenatide LA 2 mg weekly, liraglutide 1.8 mg once daily, Dulaglutide 1.5 mg) over one year and documenting changes in HbA1c and weight at 3-, 6-, 9-, and 12-months intervals. RESULTS: The study shows that while there was significant reduction in HbA1c and weight in the first 3 months, this change was not clinically significant. Also, the change was not maintained at the end of the year. By the final quarter, the effect of the medication diminishes, accompanied by a partial regain of weight. CONCLUSION: GLP1 agonists favorable initial effect on HbA1c and weight may not be sustainable beyond a certain period. The exact reason and factors contributing to this need further exploration.

Evaluation of long acting GLP1R/GCGR agonist in a DIO and biopsy-confirmed mouse model of NASH suggest a beneficial role of GLP-1/glucagon agonism in NASH patients.

OBJECTIVE: The metabolic benefits of GLP-1 receptor (GLP-1R) agonists on glycemic and weight control are well established as therapy for type 2 diabetes and obesity. Glucagon's ability to increase energy expenditure is well described, and the combination of these mechanisms-of-actions has the potential to further lower hepatic steatosis in metabolic disorders and could therefore be attractive for the treatment for non-alcoholic steatohepatitis (NASH). Here, we have investigated the effects of a dual GLP-1/glucagon receptor agonist NN1177 on hepatic steatosis, fibrosis, and inflammation in a preclinical mouse model of NASH. Having observed strong effects on body weight loss in a pilot study with NN1177, we hypothesized that direct engagement of the hepatic glucagon receptor (GCGR) would result in a superior effect on steatosis and other liver related parameters as compared to the GLP-1R agonist semaglutide at equal body weight. METHODS: Male C57Bl/6 mice were fed a diet high in trans-fat, fructose, and cholesterol (Diet-Induced Obese (DIO)-NASH) for 36 weeks. Following randomization based on the degree of fibrosis at baseline, mice were treated once daily with subcutaneous administration of a vehicle or three different doses of NN1177 or semaglutide for 8 weeks. Hepatic steatosis, inflammation and fibrosis were assessed by immunohistochemistry and morphometric analyses. Plasma levels of lipids and liver enzymes were determined, and hepatic gene expression was analyzed by RNA sequencing. RESULTS: NN1177 dose-dependently reduced body weight up to 22% compared to vehicle treatment. Plasma levels of ALT, a measure of liver injury, were reduced in all treatment groups with body weight loss. The dual agonist reduced hepatic steatosis to a greater extent than semaglutide at equal body weight loss, as demonstrated by three independent methods. Both the co-agonist and semaglutide significantly decreased histological markers of inflammation such as CD11b and Galectin-3, in addition to markers of hepatic stellate activation (αSMA) and fibrosis (Collagen I). Interestingly, the maximal beneficial effects on above mentioned clinically relevant endpoints of NN1177 treatment on hepatic health appear to be achieved with the middle dose tested. Administering the highest dose resulted in a further reduction of liver fat and accompanied by a massive induction in genes involved in oxidative phosphorylation and resulted in exaggerated body weight loss and a downregulation of a module of co-expressed genes involved in steroid hormone biology, bile secretion, and retinol and linoleic acid metabolism that are also downregulated due to NASH itself. CONCLUSIONS: These results indicate that, in a setting of overnutrition, the liver health benefits of activating the fasting-related metabolic pathways controlled by the glucagon receptor displays a bell-shaped curve. This observation is of interest to the scientific community, due to the high number of ongoing clinical trials attempting to leverage the positive effects of glucagon biology to improve metabolic health.

Relevance of GLP-1 receptor agonists or SGLT-2 inhibitors on the recruitment for clinical studies in patients with NAFLD.

INTRODUCTION: Guidelines increasingly recommend the use of glucagon-like peptide-1 receptor agonists (GLP-1 RA) or sodium-glucose co-transporter-2 inhibitors (SGLT2i) to prevent cardiovascular and cardiorenal endpoints. Both drugs also show beneficial effects in nonalcoholic fatty liver disease (NAFLD). Preexisting GLP-1 RA and SGLT2i therapies are frequently defined as exclusion criterion in clinical studies to avoid confounding effects. We therefore investigated how this might limit recruitment and design of NAFLD studies. METHODS: GLP-1 RA and SGLT2i prescriptions were analyzed in NAFLD patients with diabetes mellitus recruited at a tertiary referral center and from the population-based LIFE-Adult-Study. Individuals were stratified according to noninvasive parameters of liver fibrosis based on vibration-controlled transient elastography (VCTE). RESULTS: 97 individuals were recruited at tertiary care and 473 from the LIFE-Adult-Study. VCTE was available in 97/97 and 147/473 cases.GLP-1 RA or SGLT2i were used in 11.9% of the population-based cohort (LSM < 8 kPa), but in 32.0% with LSM ≥ 8 kPa. In the tertiary clinic, it was 30.9% overall, independent of LSM, and 36.8% in patients with medium and high risk for fibrotic NASH (FAST score > 0.35). At baseline, 3.1% of the patients in tertiary care were taking GLP-1 RA and 4.1% SGLT2i. Four years later, the numbers had increased to 15.5% and 21.6%. CONCLUSION: GLP-1 RA and SGLT2i are frequently and increasingly prescribed. In candidates for liver biopsy for NASH studies (VCTE ≥ 8 kPa) the use of them exceeds 30%, which needs careful consideration when designing NASH trials.