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.

Prescribing of evidence-based diabetes pharmacotherapy in patients with metabolic dysfunction-associated steatohepatitis

INTRODUCTION

Metabolic dysfunction-associated steatohepatitis (MASH) is highly prevalent in type 2 diabetes (T2D). Pioglitazone and glucagon-like peptide-1 receptor agonists (GLP-1RA) are medications used in T2D that can resolve MASH and should be considered in all patients with T2D and MASH. We assessed prescription rates of evidence-based T2D pharmacotherapy (EBP) in MASH, and ascertained racial/ethnic disparities in prescribing.

RESEARCH DESIGN AND METHODS

We conducted a cross-sectional study on patients in Duke University Health System with diagnosis codes for T2D and MASH between January 2019 and January 2021. Only patients with ≥1 primary care or endocrinology encounter were included. The primary outcome was EBP, defined as ≥1 prescription for pioglitazone and/or a GLP-1RA during the study period. A multivariable logistic regression model was used to examine the primary outcome.

RESULTS

A total of 847 patients with T2D and MASH were identified; mean age was 59.7 (SD 12) years, 61.9% (n=524) were female, and 11.9% (n=101) and 4.6% (n=39) were of Black race and Latino/a/x ethnicity, respectively. EBP was prescribed in 34.8% (n=295). No significant differences were noted in the rates of EBP use across racial/ethnic groups (Latino/a/x vs White patients: adjusted OR (aOR) 1.82, 95% CI 0.78 to 4.28; Black vs White patients: aOR 0.76, 95% CI 0.44 to 1.33, p=0.20).

CONCLUSIONS

EBP prescriptions, especially pioglitazone, are low in patients with T2D and MASH, regardless of race/ethnicity. These data underscore the need for interventions to close the gap between current and evidence-based care.

Optimization of a Glucagon-Like Peptide 1 Receptor Antagonist Antibody for Treatment of Hyperinsulinism

Congenital hyperinsulinism (HI) is a genetic disorder in which pancreatic β-cell insulin secretion is excessive and results in hypoglycemia that, without treatment, can cause brain damage or death. Most patients with loss-of-function mutations in ABCC8 and KCNJ11, the genes encoding the β-cell ATP-sensitive potassium channel (KATP), are unresponsive to diazoxide, the only U.S. Food and Drug Administration-approved medical therapy and require pancreatectomy. The glucagon-like peptide 1 receptor (GLP-1R) antagonist exendin-(9-39) is an effective therapeutic agent that inhibits insulin secretion in both HI and acquired hyperinsulinism. Previously, we identified a highly potent antagonist antibody, TB-001-003, which was derived from our synthetic antibody libraries that were designed to target G protein-coupled receptors. Here, we designed a combinatorial variant antibody library to optimize the activity of TB-001-003 against GLP-1R and performed phage display on cells overexpressing GLP-1R. One antagonist, TB-222-023, is more potent than exendin-(9-39), also known as avexitide. TB-222-023 effectively decreased insulin secretion in primary isolated pancreatic islets from a mouse model of hyperinsulinism, Sur1-/- mice, and in islets from an infant with HI, and increased plasma glucose levels and decreased the insulin to glucose ratio in Sur1-/- mice. These findings demonstrate that targeting GLP-1R with an antibody antagonist is an effective and innovative strategy for treatment of hyperinsulinism.

ARTICLE HIGHLIGHTS

Patients with the most common and severe form of diazoxide-unresponsive congenital hyperinsulinism (HI) require a pancreatectomy. Other second-line therapies are limited in their use because of severe side effects and short half-lives. Therefore, there is a critical need for better therapies. Studies with the glucagon-like peptide 1 receptor (GLP-1R) antagonist, avexitide (exendin-(9-39)), have demonstrated that GLP-1R antagonism is effective at lowering insulin secretion and increasing plasma glucose levels. We have optimized a GLP-1R antagonist antibody with more potent blocking of GLP-1R than avexitide. This antibody therapy is a potential novel and effective treatment for HI.

Design, synthesis, and biological evaluation of a small molecule oral agonist of the glucagon-like-peptide-1 receptor

An absolute or relative deficiency of pancreatic β-cells mass and functionality is a crucial pathological feature common to type 1 diabetes mellitus and type 2 diabetes mellitus. Glucagon-like-peptide-1 receptor (GLP1R) agonists have been the focus of considerable research attention for their ability to protect β-cell mass and augment insulin secretion with no risk of hypoglycemia. Presently commercially available GLP1R agonists are peptides that limit their use due to cost, stability, and mode of administration. To address this drawback, strategically designed distinct sets of small molecules were docked on GLP1R ectodomain and compared with previously known small molecule GLP1R agonists. One of the small molecule PK2 (6-((1-(4-nitrobenzyl)-1H-1,2,3-triazol-4-yl)methyl)-6H-indolo[2,3-b]quinoxaline) displays stable binding with GLP1R ectodomain and induces GLP1R internalization and increasing cAMP levels. PK2 also increases insulin secretion in the INS-1 cells. The oral administration of PK2 protects against diabetes induced by multiple low-dose streptozotocin administration by lowering high blood glucose levels. Similar to GLP1R peptidic agonists, treatment of PK2 induces β-cell replication and attenuate β-cell apoptosis in STZ-treated mice. Mechanistically, this protection was associated with decreased thioredoxin-interacting protein expression, a potent inducer of diabetic β-cell apoptosis and dysfunction. Together, this report describes a small molecule, PK2, as an orally active nonpeptidic GLP1R agonist that has efficacy to preserve or restore functional β-cell mass.

Comparable Cardiorenal Benefits of SGLT2 Inhibitors and GLP-1RAs in Asian and White Populations: An Updated Meta-analysis of Results From Randomized Outcome Trials

BACKGROUND

Whether the cardiorenal benefits of sodium-glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide 1 receptor agonists (GLP-1RAs) are comparable between White and Asian populations remains unclear.

PURPOSE

To compare the cardiorenal benefits of SGLT2 inhibitors and GLP-1RAs between White and Asian populations and to compare the cardiorenal benefits between the two agents in Asian patients.

DATA SOURCES

Electronic databases were searched up to 28 March 2021.

STUDY SELECTION

We included the cardiovascular (CV) and renal outcome trials of SGLT2 inhibitors and GLP-1RAs where investigators reported major adverse CV events (MACE), CV death/hospitalization for heart failure (HHF), or composite renal outcomes with stratification by race.

DATA EXTRACTION

We extracted the hazard ratio of each outcome stratified by race (Asian vs. White populations).

DATA SYNTHESIS

In 10 SGLT2 inhibitor trials, there was no significant difference between Asian and White populations for MACE (P = 0.55), CV death/HHF (P = 0.87), or composite renal outcomes (P = 0.97). In seven GLP-1RA trials, we observed a similar MACE benefit between Asian and White populations (P = 0.10). In our networkmeta-analysis we found a comparable benefit for MACE between SGLT2 inhibitors and GLP-1RAs in Asian patients.

LIMITATIONS

The data were from stratified analyses.

CONCLUSIONS

There appear to be comparable cardiorenal benefits of SGLT2 inhibitors and GLP-1RAs between Asian and White participants enrolled in CV and renal outcome trials; the two therapies seem to have similar CV benefits for Asian participants.

Mechanisms underlying the prokinetic effects of endogenous glucagon-like peptide-1 in the rat proximal colon

Glucagon-like peptide-1 (GLP-1), a well-known insulin secretagogue, is released from enteroendocrine L cells both luminally and basolaterally to exert different effects. Basolaterally released GLP-1 increases epithelial ion transport by activating CGRP-containing enteric afferent neurons. Although bath-applied GLP-1 reduced the contractility of colonic segments, GLP-1-induced stimulation of afferent neurons could also accelerate peristaltic contractions. Here, the roles of endogenous GLP-1 in regulating colonic peristalsis were investigated using isolated colonic segments. Isolated segments of rat proximal colon were placed in an organ bath, serosally perfused with oxygenated physiological salt solution, and luminally perfused with degassed 0.9% saline. Colonic wall motion was recorded using a video camera and converted into spatiotemporal maps. Intraluminal administration of GLP-1 (100 nM) stimulating the secretion of GLP-1 from L cells increased the frequency of oro-aboral propagating peristaltic contractions. The acceleratory effect of GLP-1 was blocked by luminally applied exendin-3 (9-39) (100 nM), a GLP-1 receptor antagonist. GLP-1-induced acceleration of peristaltic contractions was also prevented by bath-applied BIBN4069 (1 μM), a CGRP receptor antagonist. In colonic segments that had been exposed to bath-applied capsaicin (100 nM) that desensitizes extrinsic afferents, GLP-1 was still capable of exerting its prokinetic effect. Stimulation of endogenous GLP-1 secretion with a luminally applied cocktail of short-chain fatty acids (1 mM) increased the frequency of peristaltic waves in an exendin-3 (9-39)-sensitive manner. Thus, GLP-1 activates CGRP-expressing intrinsic afferents to accelerate peristalsis in the proximal colon. Short-chain fatty acids appear to stimulate endogenous GLP-1 secretion from L cells resulting in the acceleration of colonic peristalsis.NEW & NOTEWORTHY Glucagon-like peptide-1 (GLP-1) activates CGRP-containing intrinsic afferent neurons resulting in the acceleration of colonic peristalsis. Short-chain fatty acids stimulate the secretion of endogenous GLP-1 from L cells that accelerates colonic peristalsis. Thus, besides the well-known humoral insulinotropic action, GLP-1 exerts a local action via the activation of the enteric nervous system to accelerate colonic motility. Such a prokinetic action of GLP-1 could underlie the mechanisms causing diarrhea in patients with type-2 diabetes treated with GLP-1 analogs.

Beneficial effects of glucagon-like peptide 1 receptor agonists on glucose control, cardiovascular risk profile, and non-alcoholic fatty liver disease. An expert opinion of the Italian diabetes society

Patients with type 2 diabetes mellitus (T2DM) show an increased risk of cardiovascular diseases (CVD) and mortality. Many factors are implicated in the pathogenesis of CVD in patients with T2DM. Among the factors involved, chronic hyperglycemia and the cluster of CVD risk factors, such as dyslipidemia, hypertension, and obesity, play a major role. For many years, the control of hyperglycemia has been complicated by the fact that the use of many available drugs was associated with an increased risk of hypoglycemia. Paradoxically, hypoglycemia per se represents a risk factor for CVD. Recently, new drugs for the control of hyperglycemia have become available: many of them can determine a good control of hyperglycemia with minor risks of hypoglycemia. Among these new classes of drugs, glucagon-like peptide-1 receptor agonists (GLP-1RAs) offer many advantages. In addition to a strong anti-hyperglycemic action, they possess the ability to act on body weight and other relevant risk factors for CVD. Consistently, some of the GLP-1RAs have demonstrated, in RCT designed to assess their safety, to reduce the risk of major adverse cardiovascular events. Furthermore, GLP-1RAs possess properties useful to treat additional conditions, as the capability of improving liver damage in patients with NAFLD or NASH, highly prevalent conditions in people with T2DM. In this document, written by experts of the Italian diabetes society (SID), we will focus our attention on the therapy with GLP-1RAs in patients with T2DM, particularly on the effects on hyperglycemia, cardiovascular disease risk factors, NAFLD/NASH and CVD prevention.

Changes in markers of hepatic steatosis and fibrosis in patients with type 2 diabetes during treatment with glucagon-like peptide-1 receptor agonists. A multicenter retrospective longitudinal study

AIMS

Metabolic dysfunction-associated fatty liver disease (MAFLD) is common in people with type 2 diabetes (T2D) and can progress to advanced fibrosis and cirrhosis. In this retrospective study, we explored the longitudinal changes in markers of hepatic steatosis and fibrosis during T2D treatment with glucagon-like peptide-1 receptor agonists (GLP-1RAs).

METHODS

We analysed observational data from six diabetes outpatient clinics. In the whole T2D population, we calculated the hepatic steatosis index (HSI), which we previously validated against liver ultrasonography, and the Fibrosis (Fib)-4 index. We then identified patients who initiated a GLP-1RA from 2010 to 2018 and for whom data were available to evaluate changes in both HSI and Fib-4 scores over 24 months.

RESULTS

From 83,116 outpatients with T2D, 41,302 (49.7%) had complete data for calculating HSI and Fib-4. Most of these T2D patients (∼70%) had MAFLD (defined as HSI>36), 9.7% of whom had advanced fibrosis based on Fib-4 thresholds. Patients with low compared to high risk of advanced fibrosis were 5-times more likely to be treated with GLP-1RA. In 535 patients who initiated a GLP-1RA, the prevalence of MAFLD based on HSI declined significantly at 6 and 24 months, but Fib-4 categories did not. HSI improved significantly only in patients receiving human-based but not exendin-based GLP-1RA, while patients concomitantly receiving metformin had less worsening in Fib-4 categories.

CONCLUSIONS

MAFLD is very common among outpatients with T2D (∼70%) and the estimated prevalence of advanced fibrosis was ∼10%. Treatment with GLP-1RAs significantly improved MAFLD, but not MAFLD-associated advanced fibrosis.

Regional variation of effects of new antidiabetic medications in cardiovascular outcome trials

BACKGROUND

In international trials, glucagon-like protein-1 receptor agonists (GLP-1RAs) and sodium-glucose cotransporter-2 inhibitors (SGLT2Is) were effective in improving cardiovascular (CV) outcomes.

METHODS

We assessed the effect of GLP-1RAs and SGLT2Is treatment effect on CV endpoints by geographical region in multiple international trials using random effects weighted least squares meta-regressions.

RESULTS

The estimated effects of both SGLT2Is and GLP-1RAs on major adverse CV events (MACE) in North America (SGLT2Is n = 12,399, HR 0.90, 95% CI 0.81-1.01; GLP-1RAs n = 12,515, HR 0.95, 95% CI 0.83- 1.09) and in Europe (SGLT2Is n = 19,435, HR 0.93, 95% CI 0.85-1.02; GLP-1RAs n = 22,812, HR 0.88, 95% CI 0.79-0.99) were numerically lower but not statistically different to the rest of the world (ROW) (SGLT2Is n = 15,127, HR 0.83, 95% CI 0.75-0.92, p-value for interaction 0.26; GLP-1RAs n = 17,494, HR 0.82, 95% CI 0.73-0.92, p-value for interaction 0.28). Effects of SGLT2Is on heart failure readmission or CV death varied significantly by region (P = 0.0094). The effect of SGLT2Is was significantly smaller in Europe (n = 18,653, HR 0.86, 95% CI 0.78-0.95) than in the ROW (n = 12,463, HR 0.68, 95% CI 0.61-0.76, P = 0.0024). The smaller effect in North America (n = 9776, HR 0.76, 95% CI 0.66-0.87) did not differ significantly from that in the ROW (P = 0.2370).

CONCLUSION

The effects of SGLT2Is on HF events are larger in the ROW. Further analyses and studies are needed to better elucidate the differential effects of SGLTIs and GLP-1RAs by geographical regions.

Glucagon Potentiates Insulin Secretion Via β-Cell GCGR at Physiological Concentrations of Glucose

Incretin-potentiated glucose-stimulated insulin secretion (GSIS) is critical to maintaining euglycemia, of which GLP-1 receptor (GLP-1R) on β-cells plays an indispensable role. Recently, α-cell-derived glucagon but not intestine-derived GLP-1 has been proposed as the critical hormone that potentiates GSIS via GLP-1R. However, the function of glucagon receptors (GCGR) on β-cells remains elusive. Here, using GCGR or GLP-1R antagonists, in combination with glucagon, to treat single β-cells, α-β cell clusters and isolated islets, we found that glucagon potentiates insulin secretion via β-cell GCGR at physiological but not high concentrations of glucose. Furthermore, we transfected primary mouse β-cells with RAB-ICUE (a genetically encoded cAMP fluorescence indicator) to monitor cAMP level after glucose stimulation and GCGR activation. Using specific inhibitors of different adenylyl cyclase (AC) family members, we revealed that high glucose concentration or GCGR activation independently evoked cAMP elevation via AC5 in β-cells, thus high glucose stimulation bypassed GCGR in promoting insulin secretion. Additionally, we generated β-cell-specific GCGR knockout mice which glucose intolerance was more severe when fed a high-fat diet (HFD). We further found that β-cell GCGR activation promoted GSIS more than GLP-1R in HFD, indicating the critical role of GCGR in maintaining glucose homeostasis during nutrient overload.

Comparative efficacy of 5 sodium glucose cotransporter 2 inhibitor and 7 glucagon-like peptide 1 receptor agonists interventions on cardiorenal outcomes in type 2 diabetes patients: A network meta-analysis based on cardiovascular or renal outcome trials

BACKGROUND

Sodium glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide 1 receptor agonists (GLP-1 RAs) have been demonstrated to be able to improve the cardiovascular and renal prognosis in patients with type 2 diabetes (T2D). However, the relative efficacy of various SGLT2 inhibitors and GLP-1 RAs on cardiorenal outcomes is unestablished.

METHODS

We searched PubMed and Embase for relevant cardiovascular or renal outcome trials (CVOTs). Endpoints of interest were major adverse cardiovascular events (MACE), stroke, myocardial infarction (MI), cardiovascular death (CVD), all-cause death (ACD), kidney function progression (KFP), and hospitalization for heart failure (HHF). Bayesian network meta-analysis was conducted to produce pooled hazard ratio (HR) and 95% confidence interval (CI). We calculated the probability values of surface under the cumulative ranking curve to rank active and placebo interventions.

RESULTS

Fourteen COVTs were included in analysis. Sotagliflozin (HR 0.76, 95% CI 0.61-0.94), subcutaneous semaglutide, and albiglutide lowered MACE versus lixisenatide among others. Sotagliflozin (HR 0.59, 95% CI 0.40-0.89), canagliflozin, and empagliflozin lowered HHF versus subcutaneous semaglutide among others. Dapagliflozin and empagliflozin lowered KFP versus exenatide among others. Empagliflozin and oral semaglutide lowered CVD versus dapagliflozin among others. Sotagliflozin (HR 0.65, 95% CI 0.47-0.91) and albiglutide lowered MI versus ertugliflozin among others. Sotagliflozin (HR 0.56, 95% CI 0.37-0.85) and subcutaneous semaglutide lowered stroke versus empagliflozin among others. Oral semaglutide and empagliflozin lowered ACD versus subcutaneous semaglutide among others. The maximum surface under the cumulative ranking curve values followed sotagliflozin, subcutaneous semaglutide, and albiglutide in lowering MACE; sotagliflozin, canagliflozin, and empagliflozin in lowering HHF; dapagliflozin and empagliflozin in lowering KFP; empagliflozin and oral semaglutide in lowering CVD; sotagliflozin and albiglutide in lowering MI; sotagliflozin and subcutaneous semaglutide in lowering stroke; and oral semaglutide and empagliflozin in lowering ACD.

CONCLUSIONS

This updated network meta-analysis reproduced the findings in the first network meta-analysis, and moreover revealed that sotagliflozin was one of the most effective drugs as for lowering MI, stroke, MACE, and HHF, whereas ertugliflozin was not. These findings will provide the according evidence regarding the usage of specific SGLT2 inhibitors and GLP-1 RAs in T2D patients for prevention of specific cardiorenal endpoints.

GLP-1 (Glucagon-Like Peptide-1) Is Physiologically Relevant for Chylomicron Secretion Beyond Its Known Pharmacological Role

[Figure: see text].

Ligand-Receptor Interactions and Machine Learning in GCGR and GLP-1R Drug Discovery

The large amount of data that has been collected so far for G protein-coupled receptors requires machine learning (ML) approaches to fully exploit its potential. Our previous ML model based on gradient boosting used for prediction of drug affinity and selectivity for a receptor subtype was compared with explicit information on ligand-receptor interactions from induced-fit docking. Both methods have proved their usefulness in drug response predictions. Yet, their successful combination still requires allosteric/orthosteric assignment of ligands from datasets. Our ligand datasets included activities of two members of the secretin receptor family: GCGR and GLP-1R. Simultaneous activation of two or three receptors of this family by dual or triple agonists is not a typical kind of information included in compound databases. A precise allosteric/orthosteric ligand assignment requires a continuous update based on new structural and biological data. This data incompleteness remains the main obstacle for current ML methods applied to class B GPCR drug discovery. Even so, for these two class B receptors, our ligand-based ML model demonstrated high accuracy (5-fold cross-validation Q² > 0.63 and Q² > 0.67 for GLP-1R and GCGR, respectively). In addition, we performed a ligand annotation using recent cryogenic-electron microscopy (cryo-EM) and X-ray crystallographic data on small-molecule complexes of GCGR and GLP-1R. As a result, we assigned GLP-1R and GCGR actives deposited in ChEMBL to four small-molecule binding sites occupied by positive and negative allosteric modulators and a full agonist. Annotated compounds were added to our recently released repository of GPCR data.

A genetic map of the mouse dorsal vagal complex and its role in obesity

The brainstem dorsal vagal complex (DVC) is known to regulate energy balance and is the target of appetite-suppressing hormones, such as glucagon-like peptide 1 (GLP-1). Here we provide a comprehensive genetic map of the DVC and identify neuronal populations that control feeding. Combining bulk and single-nucleus gene expression and chromatin profiling of DVC cells, we reveal 25 neuronal populations with unique transcriptional and chromatin accessibility landscapes and peptide receptor expression profiles. GLP-1 receptor (GLP-1R) agonist administration induces gene expression alterations specific to two distinct sets of Glp1r neurons-one population in the area postrema and one in the nucleus of the solitary tract that also expresses calcitonin receptor (Calcr). Transcripts and regions of accessible chromatin near obesity-associated genetic variants are enriched in the area postrema and the nucleus of the solitary tract neurons that express Glp1r and/or Calcr, and activating several of these neuronal populations decreases feeding in rodents. Thus, DVC neuronal populations associated with obesity predisposition suppress feeding and may represent therapeutic targets for obesity.

Chronic peptide-based GIP receptor inhibition exhibits modest glucose metabolic changes in mice when administered either alone or combined with GLP-1 agonism

Combinatorial gut hormone therapy is one of the more promising strategies for identifying improved treatments for metabolic disease. Many approaches combine the established benefits of glucagon-like peptide-1 (GLP-1) agonism with one or more additional molecules with the aim of improving metabolic outcomes. Recent attention has been drawn to the glucose-dependent insulinotropic polypeptide (GIP) system due to compelling pre-clinical evidence describing the metabolic benefits of antagonising the GIP receptor (GIPR). We rationalised that benefit might be accrued from combining GIPR antagonism with GLP-1 agonism. Two GIPR peptide antagonists, GIPA-1 (mouse GIP(3–30)NH2) and GIPA-2 (NαAc-K10[γEγE-C16]-Arg18-hGIP(5–42)), were pharmacologically characterised and both exhibited potent antagonist properties. Acute in vivo administration of GIPA-1 during an oral glucose tolerance test (OGTT) had negligible effects on glucose tolerance and insulin in lean mice. In contrast, GIPA-2 impaired glucose tolerance and attenuated circulating insulin levels. A mouse model of diet-induced obesity (DIO) was used to investigate the potential metabolic benefits of chronic dosing of each antagonist, alone or in combination with liraglutide. Chronic administration studies showed expected effects of liraglutide, lowering food intake, body weight, fasting blood glucose and plasma insulin concentrations while improving glucose sensitivity, whereas delivery of either GIPR antagonist alone had negligible effects on these parameters. Interestingly, chronic dual therapy augmented insulin sensitizing effects and lowered plasma triglycerides and free-fatty acids, with more notable effects observed with GIPA-1 compared to GIPA-2. Thus, the co-administration of both a GIPR antagonist with a GLP1 agonist uncovers interesting beneficial effects on measures of insulin sensitivity, circulating lipids and certain adipose stores that seem influenced by the degree or nature of GIP receptor antagonism.

Functional GLP-1R antibodies identified from a synthetic GPCR-focused library demonstrate potent blood glucose control

G protein-coupled receptors (GPCRs) are a group of seven-transmembrane receptor proteins that have proven to be successful drug targets. Antibodies are becoming an increasingly promising modality to target these receptors due to their unique properties, such as exquisite specificity, long half-life, and fewer side effects, and their improved pharmacokinetic and pharmacodynamic profiles compared to peptides and small molecules, which results from their more favorable biodistribution. To date, there are only two US Food and Drug Administration-approved GPCR antibody drugs, namely erenumab and mogamulizumab, and this highlights the challenges encountered in identifying functional antibodies against GPCRs. Utilizing Twist's precision DNA writing technologies, we have created a GPCR-focused phage display library with 1 × 1010 diversity. Specifically, we mined endogenous GPCR binding ligand and peptide sequences and incorporated these binding motifs into the heavy chain complementarity-determining region 3 in a synthetic antibody library. Glucagon-like peptide-1 receptor (GLP-1 R) is a class B GPCR that acts as the receptor for the incretin GLP-1, which is released to regulate insulin levels in response to food intake. GLP-1 R agonists have been widely used to increase insulin secretion to lower blood glucose levels for the treatment of type 1 and type 2 diabetes, whereas GLP-1 R antagonists have applications in the treatment of severe hypoglycemia associated with bariatric surgery and hyperinsulinomic hypoglycemia. Here we present the discovery and creation of both antagonistic and agonistic GLP-1 R antibodies by panning this GPCR-focused phage display library on a GLP-1 R-overexpressing Chinese hamster ovary cell line and demonstrate their in vitro and in vivo functional activity.

Effect of antidiabetic drugs on the risk of atrial fibrillation: mechanistic insights from clinical evidence and translational studies

Diabetes mellitus (DM) is an independent risk factor for atrial fibrillation (AF), which is the most common sustained arrhythmia and is associated with substantial morbidity and mortality. Advanced glycation end product and its receptor activation, cardiac energy dysmetabolism, structural and electrical remodeling, and autonomic dysfunction are implicated in AF pathophysiology in diabetic hearts. Antidiabetic drugs have been demonstrated to possess therapeutic potential for AF. However, clinical investigations of AF in patients with DM have been scant and inconclusive. This article provides a comprehensive review of research findings on the association between DM and AF and critically analyzes the effect of different pharmacological classes of antidiabetic drugs on AF.

GIP and GLP-1 Receptor Antagonism During a Meal in Healthy Individuals

CONTEXT

The actions of both endogenous incretin hormones during a meal have not previously been characterized.

OBJECTIVE

Using specific receptor antagonists, we investigated the individual and combined contributions of endogenous glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) to postprandial glucose metabolism, energy expenditure, and gallbladder motility.

DESIGN

Randomized, double-blinded, placebo-controlled, crossover design.

SETTING

On four separate days, four liquid mixed meal tests (1894 kJ) over 270 minutes (min).

PATIENTS OR OTHER PARTICIPANTS

Twelve healthy male volunteers.

INTERVENTIONS

Infusions of the GIP receptor antagonist GIP(3-30)NH2 (800 pmol/kg/min), the GLP-1 receptor antagonist exendin(9-39)NH2 (0-20 min: 1000 pmol/kg/min; 20-270 min: 450 pmol/kg/min), GIP(3-30)NH2+exendin(9-39)NH2, or placebo/saline.

MAIN OUTCOME MEASURE

Baseline-subtracted area under the curve (bsAUC) of C-peptide.

RESULTS

Infusion of GIP(3-30)NH2+exendin(9-39)NH2 significantly increased plasma glucose excursions (bsAUC: 261 ± 142 mmol/L × min) during the liquid mixed meals compared with GIP(3-30)NH2 (180 ± 141 mmol/L × min; P = 0.048), exendin(9-39)NH2 (171 ± 114 mmol/L × min; P = 0.046), and placebo (116 ± 154 mmol/L × min; P = 0.015). Correspondingly, C-peptide:glucose ratios during GIP(3-30)NH2+exendin(9-39)NH2 infusion were significantly lower than during GIP(3-30)NH2 (P = 0.0057), exendin(9-39)NH2 (P = 0.0038), and placebo infusion (P = 0.014). GIP(3-30)NH2 resulted in significantly lower AUCs for glucagon than exendin(9-39)NH2 (P = 0.0417). Gallbladder ejection fraction was higher during GIP(3-30)NH2 compared with placebo (P = 0.004). For all interventions, energy expenditure and respiratory quotient were similar.

CONCLUSIONS

Endogenous GIP and GLP-1 lower postprandial plasma glucose excursions and stimulate insulin secretion but only endogenous GIP affects gallbladder motility. The two incretin hormones potentiate each other's effects in the control of postprandial glycemia in healthy men.

Therapeutic approaches for latent autoimmune diabetes in adults: One size does not fit all

Recent advances in the understanding of latent autoimmune diabetes in adults (LADA) pathophysiology make it increasingly evident that people with LADA comprise a heterogenous group of patients. This makes the establishment of a standard treatment algorithm challenging. On top of its glucose-lowering action, insulin may exert anti-inflammatory effects, rendering it an attractive therapeutic choice for a type of diabetes in which autoinflammation and beta cell insufficiency play major pathogenetic roles. However, there is growing evidence that other antidiabetic drugs, such as metformin, dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 receptor agonists, and thiazolidinediones, might have a role in optimizing glycemic control and preserving beta cell function in individuals with LADA, either alone or in combination with insulin. Although most of these drugs have been routinely used in the daily clinical setting for years, large prospective randomized trials are needed to assess whether they are capable of delaying progression to insulin dependence as well as their effects on diabetic complications. The aim of the present review is to discuss the current state and future perspectives of LADA therapy, emphasizing the need for individualized and patient-centered therapeutic approaches.

Advances in GLP-1 receptor targeting radiolabeled agent development and prospective of theranostics

In the light of theranostics/radiotheranostics and prospective of personalized medicine in diabetes and oncology, this review presents prior and current advances in the development of radiolabeled imaging and radiotherapeutic exendin-based agents targeting glucagon-like peptide-1 receptor. The review covers chemistry, preclinical, and clinical evaluation. Such critical aspects as structure-activity-relationship, stability, physiological potency, kidney uptake, and dosimetry are discussed.

Plasma FGF-19 Levels are Increased in Patients with Post-Bariatric Hypoglycemia

BACKGROUND

Hypoglycemia is an increasingly recognized complication of bariatric surgery. Mechanisms contributing to glucose lowering remain incompletely understood. We aimed to identify differentially abundant plasma proteins in patients with post-bariatric hypoglycemia (PBH) after Roux-en-Y gastric bypass (RYGB), compared to asymptomatic post-RYGB.

METHODS

Proteomic analysis of blood samples collected after overnight fast and mixed meal challenge in individuals with PBH, asymptomatic RYGB, severe obesity, or overweight recruited from outpatient hypoglycemia or bariatric clinics.

RESULTS

The top-ranking differentially abundant protein at 120 min after mixed meal was fibroblast growth factor 19 (FGF-19), an intestinally derived hormone regulated by bile acid-FXR signaling; levels were 2.4-fold higher in PBH vs. asymptomatic post-RYGB (mean + SEM, 1094 ± 141 vs. 428 ± 45, P < 0.001, FDR < 0.01). FGF-19 ELISA confirmed 3.5-fold higher concentrations in PBH versus asymptomatic (360 ± 70 vs. 103 ± 18, P = 0.025). To explore potential links between increased FGF-19 and GLP-1, residual samples from other human studies in which GLP-1 was modulated were assayed. FGF-19 levels did not change in response to infusion of GLP-1 and PYY in overweight/obese individuals. Infusion of the GLP-1 receptor antagonist exendin 9-39 in recently operated asymptomatic post-RYGB did not alter FGF-19 levels after mixed meal. By contrast, GLP-1 receptor antagonist infusion yielded a significant increase in FGF-19 levels after oral glucose in individuals with PBH. While plasma bile acids did not differ between PBH and asymptomatic post-RYGB, these data suggest unique interrelationships between GLP-1 and FGF-19 in PBH.

CONCLUSIONS

Taken together, these data support FGF-19 as a potential contributor to insulin-independent pathways driving postprandial hypoglycemia in PBH.

[Glucagon-like peptide 1 receptor agonists for the treatment of Type 2 diabetes]

Supraphysiological levels of the incretin hormone glucagon-like peptide 1 (GLP-1) have demonstrated a marked glucose-lowering effect in patients with Type 2 diabetes. Six GLP-1 receptor agonists are currently available for the treatment of Type 2 diabetes and have all proven to render significant reductions in both glycated haemoglobin level and body weight. However, of the clinical available compounds only liraglutide, dulaglutide and semaglutide have demonstrated reductions in the risk of cardiovascular disease. This review aims at providing an overview of the efficacy and safety of the GLP-1 receptor agonist class.

Influence of Treatment Intensification on A1c in Patients with Suboptimally Controlled Type 2 Diabetes After 2 Oral Antidiabetic Agents

BACKGROUND

In the United States, more than 50% of patients with type 2 diabetes mellitus (T2DM) have hemoglobin A1c (A1c) levels that fail to achieve the recommended target of < 7.0%. Of these, 30%-45% have an A1c > 9.0%, the threshold for poorly controlled T2DM per National Committee for Quality Assurance (NCQA) measures. Treatment inertia is a known challenge. However, recent treatment intensification patterns and outcomes after treatment fails 2 classes of oral antidiabetic agents (OADs) are not well understood.

OBJECTIVE

To characterize treatment intensification patterns and glycemic control outcomes in patients with A1c ≥ 7.0% on 2 OADs.

METHODS

A retrospective cohort study was conducted in patients with T2DM from a regional health plan claims dataset augmented with A1c results between January 1, 2010, and March 31, 2017. Patients were identified with an A1c ≥ 7.0% (baseline), while on 2 OADs, and whose treatment was intensified with basal/biphasic insulin (insulin), glucagon-like peptide-1 receptor antagonist (GLP-1RA), or a third OAD within 365 days after the baseline A1c ≥ 7.0%. Patients had at least 1 A1c value 60-365 days (follow-up period) after treatment intensification. The proportion of patients with an A1c < 7.0% and < 9.0% at follow-up were identified by therapeutic intensification strategy. Odds ratios for achieving A1c < 7.0% and < 9.0% were calculated.

RESULTS

1,226 patients were included in the analysis, and 33.5% of the patients had a baseline A1c ≥ 9.0%. 24% of patients received insulin; 16% received GLP-1RA; and 60% received a third OAD for the treatment intensification. Overall, 26.0% achieved A1c < 7.0% and 76.1% of patients achieved < 9.0%, with a median follow-up of 119 days. The proportion of patients intensified with insulin who had an A1c ≥ 9.0% at follow-up was 34.6% versus 53.2% at baseline (P < 0.01). The corresponding percentages for those intensified with a GLP-1RA and OAD were 21.6% versus 27.1% (P = 0.24) and 20.1% versus 27.3% (P < 0.01). After controlling for baseline characteristics, the odds ratio (95% CI) of achieving A1c < 7.0% and < 9.0% was 2.05 (1.45-2.90) for GLP-1RA and 0.92 (0.61-1.40) for OAD. The association between goal attainment and GLP-1RA versus OAD intensification was influenced by the time to the A1c follow-up and baseline A1c.

CONCLUSIONS

Treatment intensification was associated with improved glycemic control in patients after therapy failed 2 OADs. Patients with higher A1c at baseline were likely to initiate insulin, which was associated with a greater drop in A1c. GLP-1RA was associated with a higher likelihood of achieving NCQA-suggested glycemic control compared with a third OAD. However, the association varied by the follow-up period. These findings are important to health plans seeking to improve patient outcomes as reflected in high performance on NCQA diabetes quality measures by promoting effective and timely treatment intensification.

DISCLOSURES

Research funding was provided by Sanofi to the Pharmacotherapy Outcomes Research Center at the University of Utah and SelectHealth to conduct this study. Thomas, Sterling, and Johnstone are employees and stock/shareholders of Sanofi. Kim, Unni, McAdam-Marx, and Brixner are employees of the Department of Pharmacotherapy at the University of Utah. Brixner also has served as an advisory board member and presenter for Sanofi. McAdam-Marx also reports grants to the Department of Pharmacotherapy, University of Utah, from AstraZeneca and Janssen, outside of the submitted work. Olsen is employed by SelectHealth. Part of the results of this study was presented at the Academy of Managed Care & Specialty Pharmacy Annual Meeting 2018 in Boston, MA, during April 23-26, 2018.

The impact of the glucagon-like peptide 1 receptor agonist liraglutide on the streptozotocin-induced diabetic mouse kidney proteome

In diabetes mellitus (DM), the kidneys are exposed to increased levels of hyperglycemia-induced oxidative stress. Elevated amounts of reactive oxygen species (ROS) are believed to provoke ultrastructural changes in kidney tissue and can eventually result in DM late complications such as diabetic nephropathy. While it is reported that glucagon-like peptide 1 receptors (GLP-1R) are present in the kidney vasculature, the effects of GLP-1 on the kidney proteome in DM is not well described. Thus, we set out to investigate potential effects on the proteomic level. Here the effects of GLP-1R agonism using the GLP-1 analogue liraglutide are studied in the kidneys of streptozotocin (STZ)-treated mice (n = 6/group) by label-free shotgun mass spectrometry (MS) and targeted MS. Unsupervised and supervised multivariate analyses are followed by one-way ANOVA. Shotgun MS data of vehicle and liraglutide-treated mouse groups are separated in the supervised multivariate analysis and separation is also achieved in the subsequent unsupervised multivariate analysis using targeted MS data. The mouse group receiving the GLP-1R agonist liraglutide has increased protein abundances of glutathione peroxidase-3 (GPX3) and catalase (CATA) while the abundances of neuroplastin (NPTN) and bifunctional glutamate/proline-tRNA ligase (SYEP) are decreased compared to the STZ vehicle mice. The data suggest that GLP-1R agonism mainly influences abundances of structurally involved proteins and proteins involved in oxidative stress responses in the STZ mouse kidney. The changes could be direct effects of GLP-1R agonism in the kidneys or indirectly caused by a systemic response to GLP-1R activation.

Glucagon-like peptides-1 from phylogenetically ancient fish show potent anti-diabetic activities by acting as dual GLP1R and GCGR agonists

Glucagon-like peptides-1 (GLP-1)from phylogenetically ancient fish (lamprey, dogfish, ratfish, paddlefish and bowfin) and from a teleost, the rainbow trout produced concentration-dependent stimulations of insulin release from clonal β-cells and isolated mouse islets. Lamprey and paddlefish GLP-1 were the most potent and effective. Incubation of BRIN-BD11 cells with GLP-1 receptor (GLP1R) antagonist, exendin-4 (9-39) attenuated insulinotropic activity of all peptides whereas glucagon receptor (GCGR) antagonist [des-His¹,Pro⁴,Glu⁹] glucagon amide significantly decreased the activities of lamprey and paddlefish GLP-1 only. The GIP receptor antagonist GIP (6-30) Cex-K⁴⁰ [Pal] attenuated the activity of bowfin GLP-1. All peptides (1 μM) produced significant increases in cAMP concentration in CHL cells transfected with GLP1R but only lamprey and paddlefish GLP-1 stimulated cAMP production in HEK293 cells transfected with GCGR. Intraperitoneal administration of lamprey and paddlefish GLP-1 (25 nmol/kg body weight) in mice produced significant decreases in blood glucose and increased insulin concentrations comparable to the effects of human GLP-1. Lamprey and paddlefish GLP-1 display potent insulinotropic activity in vitro and glucose-lowering activity in vivo that is mediated through GLP1R and GCGR so that these peptides may constitute templates for design of new antidiabetic drugs.

Glucagon-related peptides from phylogenetically ancient fish reveal new approaches to the development of dual GCGR and GLP1R agonists for type 2 diabetes therapy

The insulinotropic and antihyperglycaemic properties of glucagons from the sea lamprey (Petromyzontiformes), paddlefish (Acipenseriformes) and trout (Teleostei) and oxyntomodulin from dogfish (Elasmobranchii) and ratfish (Holocephali) were compared with those of human glucagon and GLP-1 in mammalian test systems. All fish peptides produced concentration-dependent stimulation of insulin release from BRIN-BD11 rat and 1.1 B4 human clonal β-cells and isolated mouse islets. Paddlefish glucagon was the most potent and effective peptide. The insulinotropic activity of paddlefish glucagon was significantly (P < 0.01) decreased after incubating BRIN-BD11 cells with the GLP1R antagonist, exendin-4(9-39) and the GCGR antagonist [des-His¹,Pro⁴, Glu⁹] glucagon amide but GIPR antagonist, GIP(6-30)Cex-K⁴⁰[palmitate] was without effect. Paddlefish and lamprey glucagons and dogfish oxyntomodulin (10 nmol L^-1) produced significant (P < 0.01) increases in cAMP concentration in Chinese hamster lung (CHL) cells transfected with GLP1R and human embryonic kidney (HEK293) cells transfected with GCGR. The insulinotropic activity of paddlefish glucagon was attenuated in CRISPR/Cas9-engineered GLP1R knock-out INS-1 cells but not in GIPR knock-out cells. Intraperitoneal administration of all fish peptides, except ratfish oxyntomodulin, to mice together with a glucose load produced significant (P < 0.05) decreases in plasma glucose concentrations and paddlefish glucagon produced a greater release of insulin compared with GLP-1. Paddlefish glucagon shares the sequences Glu¹⁵-Glu¹⁶ and Glu²⁴-Trp²⁵-Leu²⁶-Lys²⁷-Asn²⁸-Gly²⁹ with the potent GLP1R agonist, exendin-4 so may be regarded as a naturally occurring, dual-agonist hybrid peptide that may serve as a template design of new drugs for type 2 diabetes therapy.

Suppression of Long Non-Coding RNA LINC00652 Restores Sevoflurane-Induced Cardioprotection Against Myocardial Ischemia-Reperfusion Injury by Targeting GLP-1R Through the cAMP/PKA Pathway in Mice

BACKGROUND/AIMS

Long non-coding RNA (lncRNA) and glucagon-like peptide 1 receptor (GLP-1R) are crucial for heart development and for adult heart structural maintenance and function. Herein, we performed a study to explore the effect of lncRNA LINC00652 (LINC00652) on myocardial ischemia-reperfusion (I/R) injury by targeting GLP-1R through the cyclic adenosine monophosphate-protein kinase A (cAMP/PKA) pathway.

METHODS

Bioinformatics software was used to screen the long-chain non-coding RNAs associated with myocardial ischemia-reperfusion and to predict target genes. The mRNA and protein levels of LINC00652, GLP-1R and CREB were detected by RT-qPCR and western blotting. In order to identify the interaction between LINC00652 and myocardial I/R injury, the cardiac function, the hemodynamic changes, the pathological changes of the myocardial tissues, the myocardial infarct size, and the apoptosis of myocardial cells of mice were measured. Meanwhile, the levels of serum IL-1β and TNF-α were detected.

RESULTS

LINC00652 was overexpressed in the myocardial cells of mice with myocardial I/R injury. GLP-1R is the target gene of LINC00652. We also determined higher levels of LINC00652 and GLP-1R in the I/R modeled mice. Additionally, si-LINC00652 decreased cardiac pathology, infarct size, apoptosis rates of myocardial cells, and levels of IL-1β and TNF-α, and increased GLP-1R expression cardiac function, normal hemodynamic index, and the expression and phosphorylation of GLP-1R and CREB proteins.

CONCLUSION

Taken together, our key findings of the present highlight LINC00652 inhibits the activation of the cAMP/PKA pathway by targeting GLP-1R to reduce the protective effect of sevoflurane on myocardial I/R injury in mice.

GLP-1 treatment protects endothelial cells from oxidative stress-induced autophagy and endothelial dysfunction

Endothelial dysfunction and excessively stimulated autophagy, often caused by oxidant injury or inflammation, will lead to atherosclerosis development and progression in diabetes. The aim of this study is to investigate the protective effect of glucagon-like peptide-1 (GLP-1) treatment on preventing oxidative stress-induced endothelial dysfunction and excessively stimulated autophagy. Treatment of endothelial cells with GLP-1 significantly attenuated oxidative stress-induced endothelial dysfunction and autophagy, which was associated with the reduction of intracellular reactive oxygen species (ROS) levels. These protective effects of GLP-1 were likely mediated by reducing phosphorylation of ERK1/2. We further demonstrated that GLP-1 treatment could reverse downregulation of epigenetic factor histone deacetylase 6 (HDAC6), a downstream molecular of the EKR1/2, induced by oxidant injury. In conclusion, our results suggest that GLP-1 produces a protective effect on endothelial cells from oxidant injury by preventing endothelial dysfunction and autophagy, which may be dependent on restoring HDAC6 through a GLP-1R-ERK1/2-dependent manner.

[SGLT2 inhibitor or GLP-1 receptor agonist in a type 2 diabetic patient with cardiovascular disease ?]

Sodium-glucose cotransporter type 2 inhibitors (SGLT2is), with empagliflozin in EMPA-REG OUTCOME, and glucagon-like peptide-1 receptor agonists (GLP-1RAs), with liraglutide in LEADER, have proven their ability to reduce major cardiovascular events and mortality in patients with type 2 diabetes and established cardiovascular disease. Thus clinicians have to choose between the two options in patients at high risk. The choice should be based upon a personalized approach, which has to take into account the drug properties, especially the tolerance profile, and patient's individual characteristics. In patients with heart failure, the added value of a SGLT2i appears obvious while in those with advanced renal insufficiency, current evidence favours the use of a GLP-1RA.

Antihyperglycemic medications for cardiovascular disease risk reduction

In recognition of the substantial prevalence of cardiovascular disease-related comorbidities among patients with diabetes and the potential for some agents to increase this risk, evaluation of cardiovascular outcomes is now a standard component of late-stage clinical trials involving antihyperglycemic agents. While most agents are evaluated in noninferiority trials to establish a lack of cardiovascular-related harm, a few agents have shown significant reductions in cardiovascular-related outcomes, including mortality.

Endogenous GLP-1 in lateral septum contributes to stress-induced hypophagia

Glucagon-like peptide 1 (GLP-1) neurons of the caudal brainstem project to many brain areas, including the lateral septum (LS), which has a known role in stress responses. Previously, we showed that endogenous GLP-1 in the LS plays a physiologic role in the control of feeding under non-stressed conditions, however, central GLP-1 is also involved in behavioral and endocrine responses to stress. Here, we asked whether LS GLP-1 receptors (GLP-1R) contribute to stress-induced hypophagia. Male rats were implanted with bilateral cannulas targeting the dorsal subregion of the LS (dLS). In a within-subjects design, shortly before the onset of the dark phase, rats received dLS injections of saline or the GLP-1R antagonist Exendin (9-39) (Ex9) prior to 30 min restraint stress. Food intake was measured continuously for the next 20 h. The stress-induced hypophagia observed within the first 30 min of dark was not influenced by Ex9 pretreatment, but Ex9 tended to blunt the effect of stress as early as 1 and 2 h into the dark phase. By 4-6 h, there were significant stress X drug interactions, and Ex9 pretreatment blocked the stress-induced suppression of feeding. These effects were mediated entirely through changes in average meal size; stress suppressed meal size while dLS Ex9 attenuated this effect. Using a similar design, we examined the role of dLS GLP-1R in the neuroendocrine response to acute restraint stress. As expected, stress potently increased serum corticosterone, but blockade of dLS GLP-1Rs did not affect this response. Together, these data show that endogenous GLP-1 action in the dLS plays a role in some but not all of the physiologic responses to acute stress.

Intragastric nutrient infusion reduces motivation for food in male and female rats

The idea that gut-derived satiation signals influence food reward has recently gained traction, but this hypothesis is largely based on studies focused on neural circuitry, not the peripherally released signals. Here, we directly tested the hypothesis that intragastric (IG) nutrient infusion can suppress motivation for food. In a series of experiments, IG sucrose infusion (15 kcal) significantly and reliably reduced operant responding for a sucrose reward on a progressive ratio (PR) schedule. Moreover, food deprivation for 24 h before the test session did not prevent the suppressive effect of nutrients. The suppressive effect of IG sucrose on fixed ratio 5 (FR5) operant responding was also assessed as a comparison. The effect of IG nutrients to reduce motivation was not limited to sucrose; IG Ensure infusion (9.3 kcal) also significantly reduced PR operant responding for sucrose pellets. To verify that these effects were not secondary to the osmotic challenge of concentrated nutrients, we tested IG infusion of noncaloric saline solutions equiosmolar to 40% sucrose or Ensure and found no effect. Finally, we focused on glucagon-like peptide-1 (GLP-1) and cholecystokinin (CCK) as candidate mediators for the effect of IG nutrients. Pretreatment with exendin-9, a GLP-1 receptor antagonist, delivered intraperitoneally, significantly attenuated the ability of IG nutrients to suppress PR responding and breakpoint in males, but not in females, whereas pretreatment with devazepide, a CCK_A receptor antagonist, failed to do so in both sexes. Together, these data support the idea that nutrient-induced satiation signals influence food reward and may implicate GLP-1 in this process.

Glucagon-like peptide-1 receptor antagonism impairs basal exercise capacity and vascular adaptation to aerobic exercise training in rats

Cardiorespiratory fitness (CRF) inversely predicts cardiovascular (CV) mortality and CRF is impaired in people with type 2 diabetes (T2D). Aerobic exercise training (ET) improves CRF and is associated with decreased risk of premature death in healthy and diseased populations. Understanding the mechanisms contributing to ET adaptation may identify targets for reducing CV mortality of relevance to people with T2D. The antihyperglycemic hormone glucagon-like peptide-1 (GLP-1) influences many of the same pathways as exercise and may contribute to CV adaptation to ET. We hypothesized that GLP-1 is necessary for adaptation to ET. Twelve-week-old male Wistar rats were randomized (n = 8-12/group) to receive PBS or GLP-1 receptor antagonist (exendin 9-39 (Ex(9-39)) via osmotic pump for 4 weeks ± ET. CRF was greater with ET (P < 0.01). Ex(9-39) treatment blunted CRF in both sedentary and ET rats (P < 0.001). Ex(9-39) attenuated acetylcholine-mediated vasodilation, while this response was maintained with Ex(9-39)+ET (P = 0.04). Aortic stiffness was greater with Ex(9-39) (P = 0.057) and was made worse when Ex(9-39) was combined with ET (P = 0.004). Ex vivo aortic vasoconstriction with potassium and phenylephrine was lower with Ex(9-39) (P < 0.0001). Carotid strain improved with PBS + ET but did not change in the Ex(9-39) rats with ET (P < 0.0001). Left ventricular mitochondrial respiration was elevated with Ex(9-39) (P < 0.02). GLP-1 receptor antagonism impairs CRF with and without ET, attenuates the vascular adaptation to ET, and elevates cardiac mitochondrial respiration. These data suggest that GLP-1 is integral to the adaptive vascular response to ET.

GLP-1 action in the mouse bed nucleus of the stria terminalis

Glucagon-like peptide-1 (GLP-1) injected into the brain reduces food intake. Similarly, activation of preproglucagon (PPG) cells in the hindbrain which synthesize GLP-1, reduces food intake. However, it is far from clear whether this happens because of satiety, nausea, reduced reward, or even stress. Here we explore the role of the bed nucleus of the stria terminalis (BNST), an area involved in feeding control as well as stress responses, in GLP-1 responses. Using cre-expressing mice we visualized projections of NTS PPG neurons and GLP-1R-expressing BNST cells with AAV-driven Channelrhodopsin-YFP expression. The BNST displayed many varicose YFP+ PPG axons in the ventral and less in the dorsal regions. Mice which express RFP in GLP-1R neurons had RFP+ cells throughout the BNST with the highest density in the dorsal part, suggesting that PPG neuron-derived GLP-1 acts in the BNST. Indeed, injection of GLP-1 into the BNST reduced chow intake during the dark phase, whereas injection of the GLP-1 receptor antagonist Ex9 increased feeding. BNST-specific GLP-1-induced food suppression was less effective in mice on high fat (HF, 60%) diet, and Ex9 had no effect. Restraint stress-induced hypophagia was attenuated by BNST Ex9 treatment, further supporting a role for endogenous brain GLP-1. Finally, whole-cell patch clamp recordings of RFP+ BNST neurons demonstrated that GLP-1 elicited either a depolarizing or hyperpolarizing reversible response that was of opposite polarity to that under dopamine. Our data support a physiological role for BNST GLP-1R in feeding, and suggest complex cellular responses to GLP-1 in this nucleus.

Development and characterisation of a novel glucagon like peptide-1 receptor antibody

AIMS/HYPOTHESIS

Glucagon like peptide-1 (GLP-1) enhances glucose-dependent insulin secretion by binding to GLP-1 receptors (GLP1Rs) on pancreatic beta cells. GLP-1 mimetics are used in the clinic for the treatment of type 2 diabetes, but despite their therapeutic success, several clinical effects of GLP-1 remain unexplained at a mechanistic level, particularly in extrapancreatic tissues. The aim of this study was to generate and characterise a monoclonal antagonistic antibody for the GLP1R for use in vivo.

METHODS

A naive phage display selection strategy was used to isolate single-chain variable fragments (ScFvs) that bound to GLP1R. The ScFv with the highest affinity, Glp1R0017, was converted into a human IgG1 and characterised further. In vitro antagonistic activity was assessed in a number of assays: a cAMP-based homogenous time-resolved fluorescence assay in GLP1R-overexpressing cell lines, a live cell cAMP imaging assay and an insulin secretion assay in INS-1 832/3 cells. Glp1R0017 was further tested in immunostaining of mouse pancreas, and the ability of Glp1R0017 to block GLP1R in vivo was assessed by both IPGTT and OGTT in C57/Bl6 mice.

RESULTS

Antibodies to GLP1R were selected from naive antibody phage display libraries. The monoclonal antibody Glp1R0017 antagonised mouse, human, rat, cynomolgus monkey and dog GLP1R. This antagonistic activity was specific to GLP1R; no antagonistic activity was found in cells overexpressing the glucose-dependent insulinotropic peptide receptor (GIPR), glucagon like peptide-2 receptor or glucagon receptor. GLP-1-stimulated cAMP and insulin secretion was attenuated in INS-1 832/3 cells by Glp1R0017 incubation. Immunostaining of mouse pancreas tissue with Glp1R0017 showed specific staining in the islets of Langerhans, which was absent in Glp1r knockout tissue. In vivo, Glp1R0017 reversed the glucose-lowering effect of liraglutide during IPGTTs, and reduced glucose tolerance by blocking endogenous GLP-1 action in OGTTs.

CONCLUSIONS/INTERPRETATION

Glp1R0017 is a monoclonal antagonistic antibody to the GLP1R that binds to GLP1R on pancreatic beta cells and blocks the actions of GLP-1 in vivo. This antibody holds the potential to be used in investigating the physiological importance of GLP1R signalling in extrapancreatic tissues where cellular targets and signalling pathways activated by GLP-1 are poorly understood.

Gut hormone polyagonists for the treatment of type 2 diabetes

Chemical derivatives of the gut-derived peptide hormone glucagon-like peptide 1 (GLP-1) are among the best-in-class pharmacotherapies to treat obesity and type 2 diabetes. However, GLP-1 analogs have modest weight lowering capacity, in the range of 5-10%, and the therapeutic window is hampered by dose-dependent side effects. Over the last few years, a new concept has emerged: combining the beneficial effects of several key metabolic hormones into a single molecular entity. Several unimolecular GLP-1-based polyagonists have shown superior metabolic action compared to GLP-1 monotherapies. In this review article, we highlight the history of polyagonists targeting the receptors for GLP-1, GIP and glucagon, and discuss recent progress in expanding of this concept to now allow targeted delivery of nuclear hormones via GLP-1 and other gut hormones, as a novel approach towards more personalized pharmacotherapies.

Efficacy and pharmacokinetics of subcutaneous exendin (9-39) in patients with post-bariatric hypoglycaemia

AIM

To evaluate the efficacy, pharmacokinetic (PK) profile and tolerability of subcutaneous (s.c.). exendin 9-39 (Ex-9) injection in patients with post-bariatric hypoglycaemia (PBH).

METHODS

Nine women who had recurrent symptomatic hypoglycaemia after undergoing Roux-en-Y gastric bypass were enrolled in this 2-part, single-blind, single-ascending-dose study. In Part 1, a single participant underwent equimolar low-dose intravenous (i.v.) vs s.c. Ex-9 administration; in Part 2, 8 participants were administered single ascending doses of s.c. Ex-9 during an oral glucose tolerance test (OGTT). Glycaemic, hormonal, PK and symptomatic responses were compared with those obtained during the baseline OGTT.

RESULTS

Although an exposure-response relationship was observed, all doses effectively prevented hyperinsulinaemic hypoglycaemia and improved associated symptoms. On average, the postprandial glucose nadir was increased by 66%, peak insulin was reduced by 57%, and neuroglycopenic symptoms were reduced by 80%. All doses were well tolerated with no treatment-emergent adverse events observed.

CONCLUSIONS

Injection s.c. of Ex-9 appears to represent a safe, effective and targeted therapeutic approach for treatment of PBH. Further investigation involving multiple doses with chronic dosing is warranted.

Advancing Pharmacotherapy Development from Preclinical Animal Studies

Animal models provide rapid, inexpensive assessments of an investigational drug's therapeutic potential. Ideally, they support the plausibility of therapeutic efficacy and provide a rationale for further investigation. Here, I discuss how the absence of clear effective-ineffective categories for alcohol use disorder (AUD) medications and biases in the clinical and preclinical literature affect the development of predictive preclinical alcohol dependence (AD) models. Invoking the analogical argument concept from the philosophy of science field, I discuss how models of excessive alcohol drinking support the plausibility of clinical pharmacotherapy effects. Even though these models are not likely be completely discriminative, they are sensitive to clinically effective medications and have revealed dozens of novel medication targets. In that context, I discuss recent preclinical work on GLP-1 receptor agonists, phosphodiesterase inhibitors, glucocorticoid receptor antagonists, nociception agonists and antagonists, and CRF1 antagonists. Clinically approved medications are available for each of these drug classes. I conclude by advocating a translational approach in which drugs are evaluated highly congruent preclinical models and human laboratory studies. Once translation is established, I suggest the burden is to develop hypothesis-based therapeutic interventions maximizing the impact of the confirmed pharmacotherapeutic effects in the context of additional variables falling outside the model.

Glucagon-like peptide-1 cleavage product GLP-1 (9-36) amide enhances hippocampal long-term synaptic plasticity in correlation with suppression of Kv4.2 expression and eEF2 phosphorylation

Glucagon-like peptide-1 (GLP-1) is an endogenous gut hormone and a key regulator in maintaining glucose homeostasis by stimulating insulin secretion. Its natural cleavage product GLP-1 (9-36), used to be considered a "bio-inactive" metabolite mainly because of its lack of insulinotropic effects and low affinity for GLP-1 receptors, possesses unique properties such as anti-oxidant and cardiovascular protection. Little is known about the role of GLP-1 (9-36) in central nervous system. Here we report that chronic, systemic application of GLP-1 (9-36) in adult mice facilitated both the induction and maintenance phases of hippocampal long-term potentiation (LTP), a major form of synaptic plasticity. In contrast, spatial learning and memory, as assessed by the Morris water maze test, was not altered by GLP-1 (9-36) administration. At the molecular level, GLP-1 (9-36) reduced protein levels of the potassium channel Kv4.2 in hippocampus, which is linked to elevated dendritic membrane excitability. Moreover, GLP-1(9-36) treatment inhibited phosphorylation of mRNA translational factor eEF2, which is associated with increased capacity for de novo protein synthesis. Finally, we showed that the LTP-enhancing effects by GLP-1 (9-36) treatment in vivo were blunted by application of exendin(9-39)amide [EX(9-39)], the GLP-1 receptor (GLP-1R) antagonist, suggesting its role as a GLP-1R agonist. These findings demonstrate that GLP-1 (9-36), which was considered a "bio-inactive" peptide, clearly exerts physiological effects on neuronal plasticity in the hippocampus, a brain region critical for learning and memory.

Once weekly glucagon-like peptide-1 receptor agonist albiglutide vs. prandial insulin added to basal insulin in patients with type 2 diabetes mellitus: Results over 52 weeks

We have previously reported that once-weekly albiglutide was noninferior to thrice-daily lispro for glycemic lowering, with decreased weight and risk of hypoglycemia, in patients inadequately controlled on basal insulin over 26 weeks. Findings after 52 weeks reveal similar responses to albiglutide as an add-on to insulin glargine.

Comparative adherence to diabetes drugs: An analysis of electronic health records and claims data

Non-adherence to medications is a major challenge in diabetes care. The objective of this brief report is to compare adherence rates for 6 major classes of diabetes medications: metformin, sulfonylurea, thiazolidinedione, basal insulin, DPP-4 inhibitors, and GLP-1 receptor agonists. We used a data source that linked electronic prescriptions with insurance claims to assess whether new electronic prescriptions for diabetes medications were followed by dispensing claims consistent with that prescription. After one year of follow-up, the daily medication possession probability (MPP) - a measure of overall adherence - at one year for sulfonylurea was 0.49 and for metformin was 0.46. Thiazolidinediones and basal insulin had a similar final daily MPP at 0.36 and 0.39, respectively, which was significantly lower than that for sulfonylurea or metformin (P < .05). GLP-1 receptor agonists and DPP-4 inhibitors were also comparable to one another at a final daily MPP of .30 and .21, respectively (P < .05 compared to any of the aforementioned drug classes). In summary, the rates at which diabetes drugs are prescribed, and the rates at which patients actually take them, differ substantially. Physicians should be aware of potentially significant challenges concerning adherence to newer agents.

Effect of exercise combined with glucagon-like peptide-1 receptor agonist treatment on cardiac function: A randomized double-blind placebo-controlled clinical trial

In patients with type 2 diabetes, both supervised exercise and treatment with the glucagon-like peptide-1 (GLP-1) receptor agonist (GLP-1RA) liraglutide may improve cardiac function. We evaluated cardiac function before and after 16 weeks of treatment with the GLP-1RA liraglutide or placebo, combined with supervised exercise, in 33 dysregulated patients with type 2 diabetes on diet and/or metformin. Early diastolic myocardial tissue velocity was improved by exercise in the placebo group (mean ± standard deviation [s.d.] -7.1 ± 1.6 to -7.7 ± 1.8 cm/s, P  = .01), but not in the liraglutide group (-7.1 ± 1.4 to -7.0 ± 1.4 cm/s, P  = .60; between groups, P  = .02). Similarly, the mean ± s.d. ratio of early and atrial mitral annular tissue velocities improved in the placebo group (1.0 ± 0.4 to 1.2 ± 0.4, P  = .003), but not in the liraglutide group (1.0 ± 0.3 to 1.0 ± 0.3, P  = .87; between groups, P  = .03). We found no significant differences in heart rate, left ventricular (LV) structure or function within or between the groups. In conclusion, the addition of liraglutide to exercise in sedentary patients with dysregulated type 2 diabetes may blunt the suggested beneficial effect of exercise on LV diastolic function.

Placebo-controlled, randomized trial of the addition of once-weekly glucagon-like peptide-1 receptor agonist dulaglutide to titrated daily insulin glargine in patients with type 2 diabetes (AWARD-9)

AIM

To compare the addition of weekly dulaglutide vs the addition of placebo to titrated glargine in patients with type 2 diabetes (T2D) with sub-optimum glycated haemoglobin (HbA1c) concentration.

MATERIALS AND METHODS

Patients (N = 300) from this phase III, double-blind, parallel-arm, placebo-controlled study were randomized to weekly subcutaneous injections of dulaglutide 1.5 mg or placebo with titrated daily glargine (mean ± standard deviation baseline dose: 39 ± 22 U), with or without metformin (≥1500 mg/d). The primary endpoint was superiority of dulaglutide/glargine to placebo/glargine with regard to change from baseline in HbA1c level at 28 weeks.

RESULTS

Least squares (LS) mean ± standard error (s.e.) HbA1c changes from baseline were -1.44 ± 0.09% (-15.74 ± 0.98 mmol/mol) with dulaglutide/glargine and -0.67 ± 0.09% (-7.32 ± 0.98 mmol/mol) with placebo/glargine at 28 weeks (LS mean difference [95% confidence interval] -0.77% [-0.97, -0.56]; P < .001). Body weight decreased with dulaglutide/glargine and increased with placebo/glargine (LS mean difference: -2.41 ± 0.39 kg; P < .001). Increases from baseline in mean glargine dose were significantly smaller with dulaglutide/glargine vs placebo/glargine (13 ± 2 U [0.1 ± 0.02 U/kg] vs 26 ± 2 U [0.3 ± 0.02 U/kg], respectively; P < .001; LS mean ± s.e. final dose: dulaglutide/glargine, 51 ± 2 U; placebo/glargine, 65 ± 2 U). The hypoglycaemia rate (≤3.9 mmol/L threshold) was 7.69 ± 15.15 and 8.56 ± 16.13 events/patient/year, respectively (P = .488). One episode of severe hypoglycaemia occurred in the dulaglutide/glargine group. Common gastrointestinal adverse events with dulaglutide were nausea (12.0%), diarrhoea (11.3%) and vomiting (6.0%).

CONCLUSIONS

Weekly dulaglutide 1.5 mg added to basal insulin is an efficacious and well tolerated treatment option for patients with T2D.

Treatment with GLP1 receptor agonists reduce serum CRP concentrations in patients with type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials

AIM

To undertake a systematic review and meta-analysis of randomized controlled trials of the effect of glucagon-like peptide-1 receptor agonist (GLP-1 RAs) therapy on serum C-reactive protein (CRP) concentrations.

METHOD

PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases were searched for the period up until March 16, 2016. Prospective studies evaluating the impact of GLP-1 RAs on serum CRP were identified. A random effects model (using the DerSimonian-Laird method) and generic inverse variance methods were used for quantitative data synthesis. Sensitivity analysis was conducted using the leave-one-out method. Heterogeneity was quantitatively assessed using the I² index. Random effects meta-regression was performed using unrestricted maximum likelihood method to evaluate the impact of potential moderator. International Prospective Register for Systematic Reviews (PROSPERO) number CRD42016036868.

RESULTS

Meta-analysis of the data from 7 treatment arms revealed a significant reduction in serum CRP concentrations following treatment with GLP-1 RAs (WMD -2.14 (mg/dL), 95% CI -3.51, -0.78, P=0.002; I² 96.1%). Removal of one study in the meta-analysis did not change the result in the sensitivity analysis (WMD -2.14 (mg/dL), 95% CI -3.51, -0.78, P=0.002; I² 96.1%), indicating that our results could not be solely attributed to the effect of a single study. Random effects meta-regression was performed to evaluate the impact of potential moderator on the estimated effect size. Changes in serum CRP concentration were associated with the duration of treatment (slope -0.097, 95% CI -0.158, -0.042, P<0.001).

CONCLUSIONS

This meta-analysis suggests that GLP-1 RAs therapy causes a significant reduction in CRP.