Effect of albiglutide on cardiovascular outcomes in older adults: A post hoc analysis of a randomized controlled trial.

AIM: To analyse the effects of albiglutide, a glucagon-like peptide 1 receptor agonist, on cardiovascular outcomes in older adults aged ≥65 years with type 2 diabetes and cardiovascular disease who participated in the Harmony Outcomes trial (NCT02465515). MATERIALS AND METHODS: We conducted a post hoc analysis of the primary endpoint of the Harmony Outcomes trial-time to first occurrence of a major adverse cardiovascular event-in subgroups of participants aged <65 and ≥65 years and <75 and ≥75 years at baseline. Hazard ratios and 95% confidence intervals (CIs) were generated using Cox proportional hazards regression. RESULTS: The analysis population included 9462 Harmony Outcomes participants, including 4748 patients ≥65 and 1140 patients ≥75 years at baseline. Hazard ratios for the prevention of major adverse cardiovascular events were 0.66 (95% CI, 0.53-0.82) in persons <65 and 0.86 (95% CI, 0.71-1.04) in those ≥65 years (age interaction p = .07), and 0.78 (95% CI, 0.67-0.91) in <75 and 0.70 (95% CI, 0.48-1.01) in ≥75 year age groups (interaction p = .6). When analysed as a continuous variable, age did not modify the effect of albiglutide on the primary endpoint. CONCLUSIONS: This post hoc analysis adds to the body of literature showing that glucagon-like peptide 1 receptor agonists added to standard type 2 diabetes therapy safely reduce the incidence of cardiovascular events in older adults with established cardiovascular disease. In this analysis, the risk-benefit profile was similar between younger and older age groups treated with albiglutide.

Effectiveness and cost-effectiveness of six GLP-1RAs for treatment of Chinese type 2 diabetes mellitus patients that inadequately controlled on metformin: a micro-simulation model.

Objective: To systematically estimate and compare the effectiveness and cost-effectiveness of the glucagon-like peptide-1 receptor agonists (GLP-1RAs) approved in China and to quantify the relationship between the burden of diabetic comorbidities and glycosylated hemoglobin (HbA1c) or body mass index (BMI). Methods: To estimate the costs (US dollars, USD) and quality-adjusted life years (QALY) for six GLP-1RAs (exenatide, loxenatide, lixisenatide, dulaglutide, semaglutide, and liraglutide) combined with metformin in the treatment of patients with type 2 diabetes mellitus (T2DM) which is inadequately controlled on metformin from the Chinese healthcare system perspective, a discrete event microsimulation cost-effectiveness model based on the Chinese Hong Kong Integrated Modeling and Evaluation (CHIME) simulation model was developed. A cohort of 30,000 Chinese patients was established, and one-way sensitivity analysis and probabilistic sensitivity analysis (PSA) with 50,000 iterations were conducted considering parameter uncertainty. Scenario analysis was conducted considering the impacts of research time limits. A network meta-analysis was conducted to compare the effects of six GLP-1RAs on HbA1c, BMI, systolic blood pressure, and diastolic blood pressure. The incremental net monetary benefit (INMB) between therapies was used to evaluate the cost-effectiveness. China's per capita GDP in 2021 was used as the willingness-to-pay threshold. A generalized linear model was used to quantify the relationship between the burden of diabetic comorbidities and HbA1c or BMI. Results: During a lifetime, the cost for a patient ranged from USD 42,092 with loxenatide to USD 47,026 with liraglutide, while the QALY gained ranged from 12.50 with dulaglutide to 12.65 with loxenatide. Compared to exenatide, the INMB of each drug from highest to lowest were: loxenatide (USD 1,124), dulaglutide (USD -1,418), lixisenatide (USD -1,713), semaglutide (USD -4,298), and liraglutide (USD -4,672). Loxenatide was better than the other GLP-1RAs in the base-case analysis. Sensitivity and scenario analysis results were consistent with the base-case analysis. Overall, the price of GLP-1RAs most affected the results. Medications with effective control of HbA1c or BMI were associated with a significantly smaller disease burden (p < 0.05). Conclusion: Loxenatide combined with metformin was identified as the most economical choice, while the long-term health benefits of patients taking the six GLP-1RAs are approximate.

Hot weight loss drugs tested against addiction.

Clinical trials will gauge whether GLP-1 analogs curb drug and alcohol cravings.

Glucagon-like peptide-1 analog therapy in rare genetic diseases: monogenic obesity, monogenic diabetes, and spinal muscular atrophy.

AIM: Implementing genetic analyses have unraveled rare alterations causing early-onset obesity and complications, in whom treatment is challenging. We aimed to report on the effects of adjuvant off-label therapy with liraglutide, glucagon-like peptide-1 analogue (GLP-1a), in rare genetic diagnoses. METHODS: Case scenarios and review of the literature. RESULTS: Case 1: Nine-year-old boy with early-onset severe obesity and nonalcoholic fatty liver disease (NAFLD) due to a homozygous mutation in the MC4R gene deteriorated under lifestyle change and metformin therapy [at 10.5 years: body mass index (BMI) 51.2kg/m2, 226% of the 95th percentile, fat percentage (FP) 65% and muscle-to-fat ratio (MFR) z-score of -2.41]. One year of liraglutide treatment halted progressive weight gain [BMI 50.3kg/m2, 212% of the 95th percentile, 63.7% FP and MFR z-score of -2.34], with biochemical improvement. Case 2: Twelve-year-old boy with obesity presented with diabetes and progressive NAFLD. Exome analysis revealed two heterozygous mutations compatible with monogenic diabetes (HNF1A) and familial hypercholesterolemia (LDLR). Lifestyle modifications resulted in clinical and laboratory improvement (BMI 87th percentile, 32.8% FP, MFR z-score of -1.63, HbA1c 5.5%) without the expected recovery in liver transaminases. Liraglutide treatment augmented the improvement in weight status (BMI 68th percentile, 22.6% FP, MFR z-score of -1.13) with normalization of liver transaminases. Case 3: Nineteen-year-old male with spinal muscular atrophy type 3 presented with sarcopenic obesity and comorbidities. Treatment strategy included dietary counseling and multiple drug therapies (metformin, anti-hypertensive and statins). Liraglutide therapy led to a gradual recovery of metabolic complications allowing tapering-down other medications. CONCLUSIONS: Considering the pleiotropic effects of GLP1-a beyond BMI reduction, this treatment modality may serve as a game changer in challenging cases.

Evaluación clínica y económica de análogos del GLP-1 para el tratamiento del sobrepeso / Clinical and economic evaluation of GLP-1 analogues for the treatment of overweight

CONTEXTO: El sobrepeso y la obesidad constituyen un importante problema de salud pública en todo el mundo. El tratamiento inicial consta de modificación del estilo de vida (LSM, por sus siglas en inglés) y en caso de falla, se inicia con tratamiento farmacológico como semaglutida, la cual está aprobada por agencias regulatorias internacionales y nacionales para el sobrepeso con un IMC de ≥ 25 kg/m2 a ≤ 29.9 kg/m2 y la obesidad con un IMC ≥ 30 kg/m2. El objetivo de este informe es revisar la eficacia clínica, la seguridad y la costo-efectividad de semaglutida en comparación con liraglutida para el tratamiento del sobrepeso y obesidad en la población en edad adulta sin Diabetes Mellitus tipo 2 (DM2). Ambos medicamentos cuentan con registro sanitario expedido por la Comisión Federal para la Protección contra Riesgos Sanitarios (COFEPRIS) para el tratamiento del sobrepeso y obesidad en la población en edad adulta, así como para el tratamiento de la DM2; sin embargo, en el Compendio Nacional de Insumos para la Salud (CNIS), se encuentran disponibles solamente para el tratamiento de la población en edad adulta con DM2. MÉTODOS: Se realizó una búsqueda sistemática de la literatura en diversas bases de datos. Se seleccionaron 13 documentos relevantes (2 revisiones sistemáticas [RS] con metanálisis en red [NMA, por sus siglas en inglés], 5 ensayos clínicos aleatorios [ECAs], 3 evaluaciones económicas y 3 evaluaciones de tecnologías para la salud). Las medidas de resultado fueron el cambio del peso corporal, porcentaje de eventos adversos (EAs), costos y la razón costo-efectividad incremental (RCEI). RESULTADOS: En la RS con NMA de Smith et al. (2022)2 , los resultados mostraron que, en pacientes en edad adulta con sobrepeso y obesidad, sin DM2 y con LSM, la diferencia porcentual del cambio en el peso desde el estado basal con semaglutida versus liraglutida fue de -7.02 (intervalo de confianza [IC] del 95%: - 9.61 a -4.41, 23 de 32 puntos del PRISMA NMA con un riesgo de sesgo alto) y con respecto a placebo, la diferencia porcentual fue de -12.43 (IC del 95%: -14.51 a -10.38). Los resultados para la RS con NMA de Vosoughi et al. (2021)3 , en esta misma población, indica que la diferencia de medias (DM) del cambio en el peso desde el estado basal con semaglutida versus liraglutida fue de -5.53 (IC del 95%: -7.45 a - 3.60, en 4 estudios, 52 semanas de seguimiento, con 29 de 32 puntos del PRISMA NMA con un riesgo de sesgo alto) y en la escala SUCRA semaglutida obtuvo una clasificación del 100%, lo que indica que refleja una mayor probabilidad de ser más efectiva en términos de pérdida de peso y con una menor probabilidad de presentar EAs. CONCLUSIONES: Los 5 ECAs4­8 , concluyeron que semaglutida, a una dosis de mantenimiento de 2.4 mg, presentó mayor eficacia frente a liraglutida 3.0 mg (dosis de mantenimiento) y placebo, y con una seguridad similar a la esperada en el grupo de los análogos del péptido similar al glucagón tipo 1 (GLP-1). En dos evaluaciones económicas9,10 se indicó que semaglutida fue costo-efectiva versus sus respectivos comparadores. En Kim et al. (2022) 9 los comparadores utilizados fueron ningún tratamiento, dieta y ejercicio (D&E), liraglutida 3.0 mg, fentermina/topiramato y naltrexona/bupropión; mientras que en Olivieri et al. (2022) 10 los comparadores considerados fueron D&E sola, liraglutida 3.0 mg, orlistat y naltrexona 32 mg/bupropión. Sin embargo, un tercer estudio11 mostró que semaglutida no fue costo-efectiva dados los umbrales de disposición a pagar aceptados. Los hallazgos deben interpretarse con cautela considerando las limitaciones tanto clínicas como económicas. Se requieren más estudios de semaglutida que investiguen sobre los efectos a largo plazo, estudios directos versus otras opciones de tratamiento farmacológico, y el efecto en las comorbilidades y mortalidad, con el objetivo de comprender de una mejor manera la eficacia, seguridad y costo-efectividad de semaglutida en el tratamiento de pacientes en edad adulta con sobrepeso y obesidad. De acuerdo al análisis crítico la evidencia clínica fue predominantemente de baja certeza según GRADEpro, además de un riesgo de sesgo muy serio. Con respecto a los estudios de evaluación económica, la evidencia mostró que semaglutida 2.4 mg vía SC una vez a la semana como complemento a la LSM, fue más eficaz, segura y costo-efectiva en comparación con liraglutida 3.0 mg más LSM y LSM en la población de participantes con sobrepeso y obesidad sin DM2; de acuerdo a la disponibilidad a pagar que se describe en los estudios.

Anti-diabetic effects of GLP1 analogs are mediated by thermogenic interleukin-6 signaling in adipocytes.

Mechanisms underlying anti-diabetic effects of GLP1 analogs remain incompletely understood. We observed that in prediabetic humans exenatide treatment acutely induces interleukin-6 (IL-6) secretion by monocytes and IL-6 in systemic circulation. We hypothesized that GLP1 analogs signal through IL-6 in adipose tissue (AT) and used the mouse model to test if IL-6 receptor (IL-6R) signaling underlies the effects of the GLP1-IL-6 axis. We show that liraglutide transiently increases IL-6 in mouse circulation and IL-6R signaling in AT. Metronomic liraglutide treatment resulted in AT browning and thermogenesis linked with STAT3 activation. IL-6-blocking antibody treatment inhibited STAT3 activation in AT and suppressed liraglutide-induced increase in thermogenesis and glucose utilization. We show that adipose IL-6R knockout mice still display liraglutide-induced weight loss but lack thermogenic adipocyte browning and metabolism activation. We conclude that the anti-diabetic effects of GLP1 analogs are mediated by transient upregulation of IL-6, which activates canonical IL-6R signaling and thermogenesis.

Pain relief and pain intensity response to GLP-1 receptor agonist ROSE-010 in irritable bowel syndrome; clinical study cross-analysis with respect to patient characteristics.

BACKGROUND AND AIMS: Glucagon-like peptide-1 receptor agonist ROSE-010 has been studied for management of irritable bowel syndrome (IBS). ROSE-010 showed promising effects by reducing pain during attacks of IBS. In this exploratory substudy, we cross-analyzed earlier data to identify the most suitable subpopulation for treatment with ROSE-010. METHODS: Data comprising 166 participants (116 females, 50 males) treated by subcutaneous injection with ROSE-010 at 100 µg and 300 µg versus placebo were broken down into subpopulations with recall of historical pain intensity, pain intensity immediately before treatment, gender, age, BMI, IBS subtype as well as pain intensity and pain relief of ROSE-010 with relationship to plasma glucose using visual analogue scores. Statistical cross-analysis was performed to detect optimal responders for adequate pain relief response. RESULTS: ROSE-010 gave dose- and time-dependent effects with maximum pain relief at 300 µg relative 100 µg and placebo at 120 min post injection. Females had greater pain relief than males; age and BMI did not affect treatment response. IBS pain relief was greatest in constipation-dominant IBS (IBS-C) and mixed IBS (IBS-M) relative diarrhea-dominant and unspecified IBS. CONCLUSIONS: Clinical trial data indicate that female participants are more likely than males to respond to ROSE-010 100 µg and 300 µg to achieve meaningful IBS pain relief. Maximum pain relief was achieved at 120 min with the higher dose, although this was accompanied with higher rates of nausea. Improvement of IBS pain attacks was most pronounced in IBS-C and IBS-M, suggesting these subgroups to be optimal ROSE-010 responders.

Effects of Glucagon-like peptide 1 (GLP-1) analogs in the hippocampus.

The glucagon-like peptide-1 (GLP-1) is a pleiotropic hormone very well known for its incretin effect in the glucose-dependent stimulation of insulin secretion. However, GLP-1 is also produced in the brain, and it displays critical roles in neuroprotection by activating the GLP-1 receptor signaling pathways. GLP-1 enhances learning and memory in the hippocampus, promotes neurogenesis, decreases inflammation and apoptosis, modulates reward behavior, and reduces food intake. Its pharmacokinetics have been improved to enhance the peptide's half-life, enhancing exposure and time of action. The GLP-1 agonists are successfully in clinical use for the treatment of type-2 diabetes, obesity, and clinical evaluation for the treatment of neurodegenerative diseases.

Novel glucagon-like peptide-1 analogue exhibits potency-driven G-protein biased agonism with promising effects on diabetes and diabetic dry eye syndrome.

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are considered as effective treatments for type 2 diabetes. Here, we describe the in vitro characteristics and in vivo anti-diabetic efficacies of a novel GLP-1RA, termed SM102. The in vitro functions of SM102, including GLP-1R kinetic binding parameter, cAMP activation, endocytosis and recycling, were all evaluated using the INS-1 832/13 cells expressing human GLP-1R. Chronic efficacies study was performed to evaluate the effects of SM102 on the glycemic benefits, body weight loss and other diabetic complications in db/db mice. As a result, SM102 exhibited enhanced binding affinity and potency-driven bias in favor of cAMP over GLP-1R endocytosis and ß-Arrestin 2 recruitment, as well as comparable insulin secretory response compared with Semaglutide. In addition, chronic treatment of SM102 led to more promising therapeutical effects on hyperglycemia, weight control and insulin resistance as well as dry eye syndrome (DES) than Semaglutide. Furthermore, SM102 could ameliorate diabetic DES via improving antioxidant properties, inflammatory factors and inhibiting MAPKs pathway in diabetic mice. In conclusion, SM102 is a G protein-biased agonist serving as a promising new GLP-1RA for treating diabetes and diabetic complications.

Cardioprotective Effects of Glucagon-like Peptide-1 (9-36) Against Oxidative Injury in H9c2 Cardiomyoblasts: Potential Role of the PI3K/Akt/NOS Pathway.

ABSTRACT: Glucagon-like peptide (GLP)-1(7-36), a major active form of GLP-1 hormone, is rapidly cleaved by dipeptidyl peptidase-4 to generate a truncated metabolite, GLP-1(9-36) which has a low affinity for GLP-1 receptor (GLP-1R). GLP-1(7-36) has been shown to have protective effects on cardiovascular system through GLP-1R-dependent pathway. Nevertheless, the cardioprotective effects of GLP-1(9-36) have not fully understood. The present study investigated the effects of GLP-1(9-36), including its underlying mechanisms against oxidative stress and apoptosis in H9c2 cells. Here, we reported that GLP-1(9-36) protects H9c2 cardiomyoblasts from hydrogen peroxide (H2O2)-induced oxidative stress by promoting the synthesis of antioxidant enzymes, glutathione peroxidase-1, catalase, and heme oxygenase-1. In addition, treatment with GLP-1(9-36) suppressed H2O2-induced apoptosis by attenuating caspase-3 activity and upregulating antiapoptotic proteins, Bcl-2 and Bcl-xL. These protective effects of GLP-1(9-36) are attenuated by blockade of PI3K-mediated Akt phosphorylation and prevention of nitric oxide synthase-induced nitric oxide production. Thus, GLP-1(9-36) represents the potential therapeutic target for prevention of oxidative stress and apoptosis in the heart via PI3K/Akt/nitric oxide synthase signaling pathway.

How to fill the GAPS-I in secondary prevention: application of a strategy based on GLP1 analogues, antithrombotic agents, PCSK9 inhibitors, SGLT2 inhibitors and immunomodulators.

The continuous progress in cardiovascular risk prevention strategies has led to an impressive reduction in mortality and recurrent ischemic events in patients with coronary artery disease (CAD). However, the control of several cardiovascular risk factors remains suboptimal in many CAD patients, with a high rate of recurrent events, underlying the need for more new prevention strategies. The GAPS-I (glucagon-like peptide 1 analogues, antithrombotic agents, proprotein convertase subtilisin/kexin type 9 inhibitors, sodium glucose cotransporter type 2 inhibitors and immunomodulators) strategy offers a promising potential in patients with a high-residual cardiovascular risk, who are frequently encountered in daily practice, by offering an individualized and structured approach to addressing their individual risk factors. The current review summarizes the evidence to date on each of its components, with respect to clinical outcomes and economic feasibility. The current evidence points to an efficacy of GAPS-I in reducing major adverse cardiovascular events and mortality, without a compromise on safety, albeit with the need for longer follow-up data.

GLP-1 and Underlying Beneficial Actions in Alzheimer's Disease, Hypertension, and NASH.

GLP-1 is derived from intestinal L cells, which takes effect through binding to GLP-1R and is inactivated by the enzyme dipeptidyl peptidase-4 (DPP-4). Since its discovery, GLP-1 has emerged as an incretin hormone for its facilitation in insulin release and reduction of insulin resistance (IR). However, GLP-1 possesses broader pharmacological effects including anti-inflammation, neuro-protection, regulating blood pressure (BP), and reducing lipotoxicity. These effects are interconnected to the physiological and pathological processes of Alzheimer's disease (AD), hypertension, and non-alcoholic steatohepatitis (NASH). Currently, the underlying mechanism of these effects is still not fully illustrated and a better understanding of them may help identify promising therapeutic targets of AD, hypertension, and NASH. Therefore, we focus on the biological characteristics of GLP-1, render an overview of the mechanism of GLP-1 effects in diseases, and investigate the potential of GLP-1 analogues for the treatment of related diseases in this review.

The metabolite GLP-1 (9-36) is neuroprotective and anti-inflammatory in cellular models of neurodegeneration.

Glucagon-like peptide-1 (GLP-1) is best known for its insulinotropic action following food intake. Its metabolite, GLP-1 (9-36), was assumed biologically inactive because of low GLP-1 receptor (GLP-1R) affinity and non-insulinotropic properties; however, recent studies contradict this assumption. Increased use of FDA approved GLP-1 analogues for treating metabolic disorders and neurodegenerative diseases raises interest in GLP-1 (9-36)'s biological role. We use human SH-SY5Y neuroblastoma cells and a GLP-1R over-expressing variety (#9), in both undifferentiated and differentiated states, to evaluate the neurotrophic/neuroprotective effects of GLP-1 (9-36) against toxic glutamate exposure and other oxidative stress models (via the MTS, LDH or ROS assays). In addition, we examine GLP-1 (9-36)'s signaling pathways, including cyclic-adenosine monophosphate (cAMP), protein kinase-A (PKA), and 5' adenosine monophosphate-activated protein kinase (AMPK) via the use of ELISA, pharmacological inhibitors, or GLP-1R antagonist. Human HMC3 and mouse IMG microglial cell lines were used to study the anti-inflammatory effects of GLP-1 (9-36) against lipopolysaccharide (LPS) (via ELISA). Finally, we applied GLP-1 (9-36) to primary dissociation cultures challenged with α-synuclein or amyloid-ß and assessed survival and morphology via immunochemistry. We demonstrate evidence of GLP-1R, cAMP, PKA, and AMPK-mediated neurotrophic and neuroprotective effects of GLP-1 (9-36). The metabolite significantly reduced IL-6 and TNF-α levels in HMC3 and IMG microglial cells, respectively. Lastly, we show mild but significant effects of GLP-1 (9-36) in primary neuron cultures challenged with α-synuclein or amyloid-ß. These studies enhance understanding of GLP-1 (9-36)'s effects on the nervous system and its potential as a primary or complementary treatment in pathological contexts.

[Gly²]-GLP-2, But Not Glucagon or [D-Ala²]-GLP-1, Controls Collagen Crosslinking in Murine Osteoblast Cultures.

Bone tissue is organized at the molecular level to resist fracture with the minimum of bone material. This implies that several modifications of the extracellular matrix, including enzymatic collagen crosslinking, take place. We previously highlighted the role of several gut hormones in enhancing collagen maturity and bone strength. The present study investigated the effect of proglucagon-derived peptides on osteoblast-mediated collagen post-processing. Briefly, MC3T3-E1 murine osteoblasts were cultured in the presence of glucagon (GCG), [D-Ala²]-glucagon-like peptide-1 ([D-Ala²]-GLP-1), and [Gly²]-glucagon-like peptide-2 ([Gly²]-GLP-2). Gut hormone receptor expression at the mRNA and protein levels were investigated by qPCR and Western blot. Extent of collagen postprocessing was examined by Fourier transform infrared microspectroscopy. GCG and GLP-1 receptors were not evidenced in osteoblast cells at the mRNA and protein levels. However, it is not clear whether the known GLP-2 receptor is expressed. Nevertheless, administration of [Gly²]-GLP-2, but not GCG or [D-Ala²]-GLP-1, led to a dose-dependent increase in collagen maturity and an acceleration of collagen post-processing. This mechanism was dependent on adenylyl cyclase activation. In conclusion, the present study highlighted a direct effect of [Gly²]-GLP-2 to enhance collagen post-processing and crosslinking maturation in murine osteoblast cultures. Whether this effect is translatable to human osteoblasts remains to be elucidated.

Stapled, Long-Acting Xenopus GLP-1-Based Dual GLP-1/Glucagon Receptor Agonists with Potent Therapeutic Efficacy for Metabolic Disease.

Novel peptidic glucagon receptor (GCGR) and glucagon-like peptide 1 receptor (GLP-1R) dual agonists are reported to have increased efficacy over GLP-1R monoagonists for the treatment of diabetes and obesity. We identified a novel Xenopus GLP-1-based dual GLP-1R/GCGR agonist (xGLP/GCG-13) designed with a proper activity ratio favoring the GLP-1R versus the GCGR. However, the clinical utility of xGLP/GCG-13 is limited by its short in vivo half-life. Starting from xGLP/GCG-13, dual Cys mutation was performed, followed by covalent side-chain stapling and serum albumin binder incorporation, resulting in a stabilized secondary structure, enhanced agonist potency at GLP-1R and GCGR, and improved stability. The lead peptide 2c (stapled xGLP/GCG-13 analogue with a palmitic acid albumin binder) exhibits balanced GLP-1R and GCGR activations and potent, long-lasting effects on in vivo glucose control. 2c was further explored pharmacologically in diet-induced obesity and db/db rodent models. Chronic administration of 2c potently induced body weight loss and hypoglycemic effects, improved glucose tolerance, increased energy expenditure, and normalized lipid metabolism and adiposity in relevant animal models. These results indicated that 2c has potential for development as a novel antidiabetic and/or antiobesity drug. Furthermore, we propose that the incorporation of a proper serum protein-binding motif into a di-Cys staple is an effective method for improving the stabilities and bioactivities of peptides. This approach is likely applicable to other therapeutic peptides, such as glucose-dependent insulin-tropic peptide receptor (GIPR) and GLP-1R dual agonists or GLP-1R/GCGR/GIPR triagonists.

Molecular insights into ago-allosteric modulation of the human glucagon-like peptide-1 receptor.

The glucagon-like peptide-1 (GLP-1) receptor is a validated drug target for metabolic disorders. Ago-allosteric modulators are capable of acting both as agonists on their own and as efficacy enhancers of orthosteric ligands. However, the molecular details of ago-allosterism remain elusive. Here, we report three cryo-electron microscopy structures of GLP-1R bound to (i) compound 2 (an ago-allosteric modulator); (ii) compound 2 and GLP-1; and (iii) compound 2 and LY3502970 (a small molecule agonist), all in complex with heterotrimeric Gs. The structures reveal that compound 2 is covalently bonded to C347 at the cytoplasmic end of TM6 and triggers its outward movement in cooperation with the ECD whose N terminus penetrates into the GLP-1 binding site. This allows compound 2 to execute positive allosteric modulation through enhancement of both agonist binding and G protein coupling. Our findings offer insights into the structural basis of ago-allosterism at GLP-1R and may aid the design of better therapeutics.

Impaired Ca2+ signaling due to hepatic steatosis mediates hepatic insulin resistance in Alström syndrome mice that is reversed by GLP-1 analog treatment.

Ca2+ signaling plays a critical role in the regulation of hepatic metabolism by hormones including insulin. Changes in cytoplasmic Ca2+ regulate synthesis and posttranslational modification of key signaling proteins in the insulin pathways. Emerging evidence suggests that hepatocyte intracellular Ca2+ signaling is altered in lipid-loaded liver cells isolated from obese rodent models. The mechanisms of altered Ca2+-insulin and insulin-Ca2+ signaling pathways in obesity remain poorly understood. Here, we show that the kinetics of insulin-initiated intracellular (initial) Ca2+ release from endoplasmic reticulum is significantly impaired in steatotic hepatocytes from obese Alström syndrome mice. Furthermore, exenatide, a glucagon-like peptide-1 (GLP-1) analog, reversed lipid-induced inhibition of intracellular Ca2+ release kinetics in steatotic hepatocytes, without affecting the total content of intracellular Ca2+ released. Exenatide reversed the lipid-induced inhibition of intracellular Ca2+ release, at least partially, via lipid reduction in hepatocytes, which then restored hormone-regulated cytoplasmic Ca2+ signaling and insulin sensitivity. This data provides additional evidence for the important role of Ca2+ signaling pathways in obesity-associated impaired hepatic lipid homeostasis and insulin signaling. It also highlights a potential advantage of GLP-1 analogs when used to treat type 2 diabetes associated with hepatic steatosis.

GLP-1 improves the neuronal supportive ability of astrocytes in Alzheimer's disease by regulating mitochondrial dysfunction via the cAMP/PKA pathway.

The glucagon-like peptide-1 (GLP-1) was shown to have neuroprotective effects in Alzheimer's disease (AD). However, the underlying mechanism remains elusive. Astrocytic mitochondrial abnormalities have been revealed to constitute important pathologies. In the present study, we investigated the role of astrocytic mitochondria in the neuroprotective effect of GLP-1 in AD. To this end, 6-month-old 5 × FAD mice were subcutaneously treated with liraglutide, a GLP-1 analogue (25 nmol/kg/qd) for 8 weeks. Liraglutide ameliorated mitochondrial dysfunction and prevented neuronal loss with activation of the cyclic adenosine 3',5'-monophosphate (cAMP)/phosphorylate protein kinase A (PKA) pathway in the brain of 5 × FAD mice. Next, we exposed astrocytes to ß-amyloid (Aß) in vitro and treated them with GLP-1. By activating the cAMP/PKA pathway, GLP-1 increased the phosphorylation of DRP-1 at the s637 site and mitigated mitochondrial fragmentation in Aß-treated astrocytes. GLP-1 further improved the Aß-induced energy failure, mitochondrial reactive oxygen species (ROS) overproduction, mitochondrial membrane potential (MMP) collapse, and cell toxicity in astrocytes. Moreover, GLP-1 also promoted the neuronal supportive ability of Aß-treated astrocytes via the cAMP/PKA pathway. This study revealed a new mechanism behind the neuroprotective effect of GLP-1 in AD.