2554 results found
Hinds CE, Peace E, Chen S, et al., 2024, Abolishing β-arrestin recruitment is necessary for the full metabolic benefits of G protein-biased glucagon-like peptide-1 receptor agonists, Diabetes, Obesity and Metabolism: a journal of pharmacology and therapeutics, Vol: 26, Pages: 65-77, ISSN: 1462-8902
AimEarlier studies have shown that peptide glucagon-like peptide-1 receptor (GLP-1R) agonists with reduced β-arrestin recruitment show enhanced anti-hyperglycaemic efficacy through avoidance of GLP-1R desensitization. However, the ligand modifications needed to decrease β-arrestin recruitment usually also reduces GLP-1R affinity, therefore higher doses are needed. Here we aimed to develop new, long-acting, G protein-biased GLP-1R agonists with acute signalling potency comparable with semaglutide, to provide insights into specific experimental and therapeutic scenarios.Materials and MethodsNew GLP-1R agonist peptides were assessed using a variety of in vitro and in vivo assays.ResultsFirst, we show that very substantial reductions in β-arrestin recruitment efficacy are required to realize fully the benefits of GLP-1R agonism on blood glucose lowering in mice, with more moderate reductions being less effective. Secondly, our lead compound (SRB107) performs substantially better than semaglutide for effects on blood glucose and weight loss, which may be jointly attributable to its biased agonist action and protracted pharmacokinetics. Thirdly, we show that biased agonist-specific GLP-1R internalization profiles occur at clinically relevant pharmacological concentrations. Finally, we show that SRB107 cAMP signalling is differentially modulated by single and double GLP1R coding variants seen in human populations, with implications for GLP-1R agonist pharmacogenomics.ConclusionsCompletely abolishing β-arrestin recruitment improves the anti-hyperglycaemic effects of GLP-1R agonists in mice.
McGlone ER, Siebert M, Dore M, et al., 2023, Sleeve gastrectomy causes weight-loss independent improvements in hepatic steatosis, Liver International, Vol: 43, Pages: 1890-1900, ISSN: 1478-3223
Background and AimsSleeve gastrectomy (VSG) leads to improvement in hepatic steatosis, associated with weight loss. The aims of this study were to investigate whether VSG leads to weight-loss independent improvements in liver steatosis in mice with diet-induced obesity (DIO); and to metabolically and transcriptomically profile hepatic changes in mice undergoing VSG.MethodsMice with DIO were treated with VSG, sham surgery with subsequent food restriction to weight-match to the VSG group (Sham-WM), or sham surgery with return to unrestricted diet (Sham-Ad lib). Hepatic steatosis, glucose tolerance, insulin and glucagon resistance, and hepatic transcriptomics were investigated at the end of the study period and treatment groups were compared with mice undergoing sham surgery only (Sham-Ad lib).ResultsVSG led to much greater improvement in liver steatosis than Sham-WM (liver triglyceride mg/mg 2.5 ± 0.1, 2.1 ± 0.2, 1.6 ± 0.1 for Sham-AL, Sham-WM and VSG respectively; p = 0.003). Homeostatic model assessment of insulin resistance was improved following VSG only (51.2 ± 8.8, 36.3 ± 5.3, 22.3 ± 6.1 for Sham-AL, Sham-WM and VSG respectively; p = 0.03). The glucagon-alanine index, a measure of glucagon resistance, fell with VSG but was significantly increased in Sham-WM (9.8 ± 1.7, 25.8 ± 4.6 and 5.2 ± 1.2 in Sham Ad-lib, Sham-WM and VSG respectively; p = 0.0003). Genes downstream of glucagon receptor signalling which govern fatty acid synthesis (Acaca, Acacb, Me1, Acly, Fasn and Elovl6) were downregulated following VSG but upregulated in Sham-WM.ConclusionsChanges in glucagon sensitivity may contribute to weight-loss independent improvements in hepatic steatosis following VSG.
Kowalka AM, Alexiadou K, Cuenco J, et al., 2023, The postprandial secretion of peptide YY<sub>1-36</sub> and <sub>3-36</sub> in obesity is differentially increased after gastric bypass versus sleeve gastrectomy, CLINICAL ENDOCRINOLOGY, Vol: 99, Pages: 272-284, ISSN: 0300-0664
Patel P, Thomas R, Hamady M, et al., 2023, EMBIO trial study protocol: left gastric artery embolisation for weight loss in patients living with obesity with a BMI 35-50 kg/m², BMJ Open, Vol: 13, ISSN: 2044-6055
Introduction Left gastric artery embolisation (LGAE) is a well-established treatment for major upper gastrointestinal (GI) bleeding when control is not established via upper GI endoscopy and recently has shown promising results for weight loss in small single arm studies. LGAE could be a treatment option in between our current tier-3 and tier-4 services for obesity. EMBIO is a National Institute for Health Research funded trial, a multicentre double-blinded randomised controlled trial between Imperial College National Health Service Trust and University College London Hospital, comparing LGAE versus Placebo procedure. The key aims of the trial is to evaluate LGAE efficacy on weight loss, its mechanism of action, safety profile and obesity-related comorbidities.Methods and analysis 76 participants will be recruited from the existing tier-3 database after providing informed consent. Key inclusion criteria include adults aged 18–70 with a body mass index 35–50 kg/m2 and appropriate anatomy of the left gastric artery and coeliac plexus on CT Angiogram. Key exclusion criteria included previous major abdominal and bariatric surgery, weight >150 kg, type 2 diabetes on any medications other than metformin and the use of weight modifying medications. Participants will undergo mechanistic visits 1 week prior to the intervention and 3, 6 and 12 months postintervention. Informed consent will be received from each participant and they will be randomised in a 1:1 ratio to left gastric artery embolisation and placebo treatment. Blinding strategies include the use of moderate doses of sedation, visual and auditory isolation. All participants will enter a tier-3 weight management programme postintervention. The primary analysis will estimate the difference between the groups in the mean per cent weight loss at 12 months.Ethics and dissemination This trial shall be conducted in full conformity with the 1964 Declaration of Helsinki and
The peptide hormone glucagon, discovered in late 1922, is secreted from pancreatic alpha cells and is an essential regulator of metabolic homeostasis. This review summarises experiences since the discovery of glucagon regarding basic and clinical aspects of this hormone and speculations on the future directions for glucagon biology and glucagon-based therapies. The review was based on the international glucagon conference, entitled 'A hundred years with glucagon and a hundred more', held in Copenhagen, Denmark, in November 2022. The scientific and therapeutic focus of glucagon biology has mainly been related to its role in diabetes. In type 1 diabetes, the glucose-raising properties of glucagon have been leveraged to therapeutically restore hypoglycaemia. The hyperglucagonaemia evident in type 2 diabetes has been proposed to contribute to hyperglycaemia, raising questions regarding underlying mechanism and the importance of this in the pathogenesis of diabetes. Mimicry experiments of glucagon signalling have fuelled the development of several pharmacological compounds including glucagon receptor (GCGR) antagonists, GCGR agonists and, more recently, dual and triple receptor agonists combining glucagon and incretin hormone receptor agonism. From these studies and from earlier observations in extreme cases of either glucagon deficiency or excess secretion, the physiological role of glucagon has expanded to also involve hepatic protein and lipid metabolism. The interplay between the pancreas and the liver, known as the liver-alpha cell axis, reflects the importance of glucagon for glucose, amino acid and lipid metabolism. In individuals with diabetes and fatty liver diseases, glucagon's hepatic actions may be partly impaired resulting in elevated levels of glucagonotropic amino acids, dyslipidaemia and hyperglucagonaemia, reflecting a new, so far largely unexplored pathophysiological phenomenon termed 'glucagon resistance'. Importantly, the hyperglucagonaemia as part of
Behary P, Alessimii H, Miras AD, et al., 2023, Tripeptide gut hormone infusion does not alter food preferences or sweet taste function in volunteers with obesity and prediabetes/diabetes but promotes restraint eating: a secondary analysis of a randomized single-blind placebo-controlled study, Diabetes, Obesity and Metabolism: a journal of pharmacology and therapeutics, Vol: 25, Pages: 1731-1739, ISSN: 1462-8902
AimsTo investigate whether the elevation in postprandial concentrations of the gut hormones glucagon-like peptide-1 (GLP-1), oxyntomodulin (OXM) and peptide YY (PYY) accounts for the beneficial changes in food preferences, sweet taste function and eating behaviour after Roux-en-Y gastric bypass (RYGB).Materials and methodsThis was a secondary analysis of a randomized single-blind study in which we infused GLP-1, OXM, PYY (GOP) or 0.9% saline subcutaneously for 4 weeks in 24 subjects with obesity and prediabetes/diabetes, to replicate their peak postprandial concentrations, as measured at 1 month in a matched RYGB cohort (ClinicalTrials.gov NCT01945840). A 4-day food diary and validated eating behaviour questionnaires were completed. Sweet taste detection was measured using the method of constant stimuli. Correct sucrose identification (corrected hit rates) was recorded, and sweet taste detection thresholds (EC50s: half maximum effective concencration values) were derived from concentration curves. The intensity and consummatory reward value of sweet taste were assessed using the generalized Labelled Magnitude Scale.ResultsMean daily energy intake was reduced by 27% with GOP but no significant changes in food preferences were observed, whereas a reduction in fat and increase in protein intake were seen post-RYGB. There was no change in corrected hit rates or detection thresholds for sucrose detection following GOP infusion. Additionally, GOP did not alter the intensity or consummatory reward value of sweet taste. A significant reduction in restraint eating, comparable to the RYGB group was observed with GOP.ConclusionThe elevation in plasma GOP concentrations after RYGB is unlikely to mediate changes in food preferences and sweet taste function after surgery but may promote restraint eating.
Kowalka AMM, Alexiadou K, Cuenco J, et al., 2023, Commentary on "The road to reliable peptide assays is paved with good guidelines", CLINICAL ENDOCRINOLOGY, Vol: 98, Pages: 763-765, ISSN: 0300-0664
Braude M, Roberts S, Majeed A, et al., 2023, Liver stiffness (Fibroscan®) is a predictor of all-cause mortality in people with non-alcoholic fatty liver disease, LIVER INTERNATIONAL, Vol: 43, Pages: 90-99, ISSN: 1478-3223
Hope D, Hinds C, Lopes T, et al., 2022, Hypoaminoacidemia underpins glucagon-mediated energy expenditure and weight loss, Cell Reports Medicine, Vol: 3, ISSN: 2666-3791
Glucagon analogues show promise as components of next-generation, multi-target, anti-obesity therapeutics. The biology of chronic glucagon treatment, in particular its ability to induce energy expenditure and weight loss, remains poorly understood. Using a long-acting glucagon analogue, G108, we demonstrate that glucagon-mediated body weight loss is intrinsically linked to the hypoaminoacidemia associated with its known amino acid catabolic action. Mechanistic studies reveal an energy-consuming response to low plasma amino acids in G108-treated mice, prevented by dietary amino acid supplementation and mimicked by a rationally designed low amino acid diet. Therefore, low plasma amino acids are a prerequisite for G108-mediated energy expenditure and weight loss. However, preventing hypoaminoacidemia with additional dietary protein does not affect the ability of G108 to improve glycemia or hepatic steatosis in obese mice. These studies provide a mechanism for glucagon-mediated weight loss and confirm the hepatic glucagon receptor as an attractive molecular target for metabolic disease therapeutics.
McGlone ER, Dunsterville C, Carling D, et al., 2022, Hepatocyte cholesterol content modulates glucagon receptor signalling, Molecular Metabolism, Vol: 63, ISSN: 2212-8778
ObjectiveTo determine whether glucagon receptor (GCGR) actions are modulated by cellular cholesterol levels.MethodsWe determined the effects of experimental cholesterol depletion and loading on glucagon-mediated cAMP production, ligand internalisation and glucose production in human hepatoma cells, mouse and human hepatocytes. GCGR interactions with lipid bilayers were explored using coarse-grained molecular dynamic simulations. Glucagon responsiveness was measured in mice fed a high cholesterol diet with or without simvastatin to modulate hepatocyte cholesterol content.ResultsGCGR cAMP signalling was reduced by higher cholesterol levels across different cellular models. Ex vivo glucagon-induced glucose output from mouse hepatocytes was enhanced by simvastatin treatment. Mice fed a high cholesterol diet had increased hepatic cholesterol and a blunted hyperglycaemic response to glucagon, both of which were partially reversed by simvastatin. Simulations identified likely membrane-exposed cholesterol binding sites on the GCGR, including a site where cholesterol is a putative negative allosteric modulator.ConclusionsOur results indicate that cellular cholesterol content influences glucagon sensitivity and indicate a potential molecular basis for this phenomenon. This could be relevant to the pathogenesis of non-alcoholic fatty liver disease, which is associated with both hepatic cholesterol accumulation and glucagon resistance.
Patel P, Thomas R, Hamady M, et al., 2022, O102 We know about left gastric artery embolisation and will embio provide the next solution to treat obesity?, Annual Scientific Meeting of the Surgical-Research-Society, Publisher: OXFORD UNIV PRESS, ISSN: 0007-1323
Patel P, Thomas R, Hamady M, et al., 2022, What we know about left gastric artery embolisation and will EMBIO provide the next solution to treat obesity?, Publisher: SPRINGER, Pages: 26-27, ISSN: 0960-8923
Patel P, Thomas R, Hamady M, et al., 2022, Simulation training to create the gold standard framework to run the EMBIO trial (left gastric artery embolisation vs placebo), a double blinded, multi-centre, randomised controlled trial., 13th Annual Scientific Meeting of the British-Obesity-and-Metabolic-Surgery-Society (BOMSS), Publisher: SPRINGER, Pages: 27-27, ISSN: 0960-8923
Braude M, Majeed A, Roberts S, et al., 2022, Increased liver stiffness on vibration controlled transient elastography (Fibroscan) as a predictor of all-cause mortality in people with fatty liver disease, Publisher: ELSEVIER, Pages: S441-S442, ISSN: 0168-8278
Suba K, Patel YS, Roberts A, et al., 2022, The Role of Intraislet Glucagon in Pulsatile Insulin Secretion, Publisher: AMER DIABETES ASSOC, ISSN: 0012-1797
Davies I, Dong J, Hope D, et al., 2022, Chronic glucagon administration does not induce inguinal white adipose tissue browning in rats, Publisher: WILEY, ISSN: 0742-3071
Jones B, Sands C, Alexiadou K, et al., 2022, The metabolomic effects of tripeptide gut hormone infusion compared to Roux-en-Y gastric bypass and caloric restriction, Journal of Clinical Endocrinology and Metabolism, Vol: 107, Pages: e767-e782, ISSN: 0021-972X
Context: The gut-derived peptide hormones glucagon-like peptide-1 (GLP-1), oxyntomodulin (OXM), and peptide YY (PYY) are regulators of energy intake and glucose homeostasis, and are thought to contribute to the glucose-lowering effects of bariatric surgery. Objective: To establish the metabolomic effects of a combined infusion of GLP-1, OXM and PYY (tripeptide “GOP”) in comparison to a placebo infusion, Roux-en-Y gastric bypass (RYGB) surgery, and a very low-calorie diet (VLCD). Design and setting: Sub-analysis of a single-blind, randomised, placebo-controlled study of GOP infusion (ClinicalTrials.gov NCT01945840), including VLCD and RYGB comparator groups. Patients and interventions: 25 obese patients with type 2 diabetes or prediabetes were randomly allocated to receive a 4-week subcutaneous infusion of GOP (n=14) or 0.9% saline control (SAL; n=11). An additional 22 patients followed a VLCD, and 21 underwent RYGB surgery. Main outcome measures: Plasma and urine samples collected at baseline and 4 weeks into each intervention were subjected to cross-platform metabolomic analysis, followed by unsupervised and supervised modelling approaches to identify similarities and differences between the effects of each intervention. Results: Aside from glucose, very few metabolites were affected by GOP, contrasting with major metabolomic changes seen with VLCD and RYGB. Conclusions: Treatment with GOP provides a powerful glucose-lowering effect but does not replicate the broader metabolomic changes seen with VLCD and RYGB. The contribution of these metabolomic changes to the clinical benefits of RYGB remains to be elucidated.
Bloom S, Thames FC, 2021, Nomination and list placement of ethnic minorities under open-list proportional rules: The centrality of ethnopolitical context, Electoral Studies, Vol: 74, ISSN: 0261-3794
Do parties respond to ethnopolitical context when nominating and placing ethnic minority candidates in open-list proportional representation (PR) systems? Open-list PR is by nature candidate centered. Candidates need to attract preference votes to succeed. Political leaders, we argue, anticipate candidates' ability to generate support and the extent of anti-minority sentiment in districts when nominating and placing candidates. To test our arguments, we analyze data on 8945 candidates competing across 124 localities in Latvia's 2017 local elections. Few studies have explored open-list systems in countries like Latvia where preference voting routinely alters list order. Other studies stress the role that context plays in ethnic minority representation, but often lack data on crucial indicators. Our results show that parties nominated more minority candidates in localities with more ethnic minority voters and fewer in those with larger noncitizen populations. We did not, however, find that ethnopolitical context affected list placement.
Hinds CE, Owen BM, Hope DCD, et al., 2021, A glucagon analogue decreases body weight in mice via signalling in the liver., Scientific Reports, Vol: 11, Pages: 1-17, ISSN: 2045-2322
Glucagon receptor agonists show promise as components of next generation metabolic syndrome pharmacotherapies. However, the biology of glucagon action is complex, controversial, and likely context dependent. As such, a better understanding of chronic glucagon receptor (GCGR) agonism is essential to identify and mitigate potential clinical side-effects. Herein we present a novel, long-acting glucagon analogue (GCG104) with high receptor-specificity and potent in vivo action. It has allowed us to make two important observations about the biology of sustained GCGR agonism. First, it causes weight loss in mice by direct receptor signalling at the level of the liver. Second, subtle changes in GCG104-sensitivity, possibly due to interindividual variation, may be sufficient to alter its effects on metabolic parameters. Together, these findings confirm the liver as a principal target for glucagon-mediated weight loss and provide new insights into the biology of glucagon analogues.
McGlone ER, Manchanda Y, Jones B, et al., 2021, Receptor Activity-Modifying Protein 2 (RAMP2) alters glucagon receptor trafficking in hepatocytes with functional effects on receptor signalling, Molecular Metabolism, Vol: 53, Pages: 1-11, ISSN: 2212-8778
ObjectivesReceptor Activity-Modifying Protein 2 (RAMP2) is a chaperone protein which allosterically binds to and interacts with the glucagon receptor (GCGR). The aims of this study were to investigate the effects of RAMP2 on GCGR trafficking and signalling in the liver, where glucagon (GCG) is important for carbohydrate and lipid metabolism.MethodsSubcellular localisation of GCGR in the presence and absence of RAMP2 was investigated using confocal microscopy, trafficking and radioligand binding assays in human embryonic kidney (HEK293T) and human hepatoma (Huh7) cells. Mouse embryonic fibroblasts (MEFs) lacking Wiskott Aldrich Syndrome protein and scar homologue (WASH) complex and the trafficking inhibitor monensin were used to investigate the effect of a halt in recycling of internalised proteins on GCGR subcellular localisation and signalling in the absence of RAMP2. NanoBiT complementation and cyclic AMP assays were used to study the functional effect of RAMP2 on the recruitment and activation of GCGR signalling mediators. Response to hepatic RAMP2 up-regulation in lean and obese adult mice using a bespoke adeno-associated viral vector was also studied.ResultsGCGR is predominantly localised at the plasma membrane in the absence of RAMP2 and exhibits remarkably slow internalisation in response to agonist stimulation. Rapid intracellular accumulation of GCG-stimulated GCGR in cells lacking WASH complex or in the presence of monensin indicates that activated GCGRs undergo continuous cycles of internalisation and recycling despite apparent GCGR plasma membrane localisation up to 40 minutes post-stimulation. Co-expression of RAMP2 induces GCGR internalisation both basally and in response to agonist stimulation. The intracellular retention of GCGR in the presence of RAMP2 confers a bias away from β-arrestin-2 recruitment coupled to increased activation of Gαs proteins at endosomes. This is associated with increased short-term efficacy for glucagon-stimulated
Lucey M, Ashik T, Marzook A, et al., 2021, Acylation of the incretin peptide exendin-4 directly impacts GLP-1 receptor signalling and trafficking, Molecular Pharmacology, Vol: 100, Pages: 319-334, ISSN: 0026-895X
The glucagon-like peptide-1 receptor (GLP-1R) is a class B G protein-coupled receptor and mainstay therapeutic target for the treatment of type 2 diabetes and obesity. Recent reports have highlighted how biased agonism at the GLP-1R affects sustained glucose-stimulated insulin secretion through avoidance of desensitisation and downregulation. A number of GLP-1R agonists (GLP-1RAs) feature a fatty acid moiety to prolong their pharmacokinetics via increased albumin binding, but the potential for these chemical changes to influence GLP-1R function has rarely been investigated beyond potency assessments for cyclic adenosine monophosphate (cAMP). Here we directly compare the prototypical GLP-1RA exendin-4 with its C-terminally acylated analogue, exendin-4-C16. We examine relative propensities of each ligand to recruit and activate G proteins and β-arrestins, endocytic and post-endocytic trafficking profiles, and interactions with model and cellular membranes in HEK293 and HEK293T cells. Both ligands had similar cAMP potency but exendin-4-C16 showed ~2.5-fold bias towards G protein recruitment and a ~60% reduction in β-arrestin-2 recruitment efficacy compared to exendin-4, as well as reduced GLP-1R endocytosis and preferential targeting towards recycling pathways. These effects were associated with reduced movement of the GLP-1R extracellular domain measured using a conformational biosensor approach, and a ~70% increase in insulin secretion in INS-1 832/3 cells. Interactions with plasma membrane lipids were enhanced by the acyl chain. Exendin-4-C16 showed extensive albumin binding and was highly effective for lowering of blood glucose in mice over at least 72 hours. Our study highlights the importance of a broad approach to the evaluation of GLP-1RA pharmacology.
Pickford P, Lucey M, Rujan R-M, et al., 2021, Partial agonism improves the anti-hyperglycaemic efficacy of an oxyntomodulin-derived GLP-1R/GCGR co-agonist, Molecular Metabolism, Vol: 51, ISSN: 2212-8778
OBJECTIVE: Glucagon-like peptide-1 and glucagon receptor (GLP-1R/GCGR) co-agonism can maximise weight loss and improve glycaemic control in type 2 diabetes and obesity. In this study we investigated the cellular and metabolic effects of modulating the balance between G protein and β-arrestin-2 recruitment at GLP-1R and GCGR using oxyntomodulin (OXM)-derived co-agonists. This strategy has been previously shown to improve the duration of action of GLP-1R mono-agonists by reducing target desensitisation and downregulation. METHODS: Dipeptidyl dipeptidase-4 (DPP-4)-resistant OXM analogues were generated and assessed for a variety of cellular readouts. Molecular dynamic simulations were used to gain insights into the molecular interactions involved. In vivo studies were performed in mice to identify effects on glucose homeostasis and weight loss. RESULTS: Ligand-specific reductions in β-arrestin-2 recruitment were associated with slower GLP-1R internalisation and prolonged glucose-lowering action in vivo. The putative benefits of GCGR agonism were retained, with equivalent weight loss compared to the GLP-1R mono-agonist liraglutide in spite of a lesser degree of food intake suppression. The compounds tested showed only a minor degree of biased agonism between G protein and β-arrestin-2 recruitment at both receptors and were best classified as partial agonists for the two pathways measured. CONCLUSIONS: Diminishing β-arrestin-2 recruitment may be an effective way to increase the therapeutic efficacy of GLP-1R/GCGR co-agonists. These benefits can be achieved by partial rather than biased agonism.
Marzook A, Chen S, Pickford P, et al., 2021, Evaluation of efficacy- versus affinity-driven agonism with biased GLP-1R ligands P5 and exendin-F1, Biochemical Pharmacology, Vol: 190, Pages: 1-12, ISSN: 0006-2952
The glucagon-like peptide-1 receptor (GLP-1R) is an important regulator of glucose homeostasis and has been successfully targeted for the treatment of type 2 diabetes. Recently described biased GLP-1R agonists with selective reductions in β-arrestin versus G protein coupling show improved metabolic actions in vivo. However, two prototypical G protein-favouring GLP-1R agonists, P5 and exendin-F1, are reported to show divergent effects on insulin secretion. In this study we aimed to resolve this discrepancy by performing a side-by-side characterisation of these two ligands across a variety of in vitro and in vivo assays. Exendin-F1 showed reduced acute efficacy versus P5 for several readouts, including recruitment of mini-G proteins, G protein-coupled receptor kinases (GRKs) and β-arrestin-2. Maximal responses were also lower for both GLP-1R internalisation and the presence of active GLP-1R-mini-Gs complexes in early endosomes with exendin-F1 treatment. In contrast, prolonged insulin secretion in vitro and sustained anti-hyperglycaemic efficacy in mice were both greater with exendin-F1 than with P5. We conclude that the particularly low acute efficacy of exendin-F1 and associated reductions in GLP-1R downregulation appear to be more important than preservation of endosomal signalling to allow sustained insulin secretion responses. This has implications for the ongoing development of affinity- versus efficacy-driven biased GLP-1R agonists as treatments for metabolic disease.
Salem V, Demetriou L, Behary P, et al., 2021, Weight loss by low calorie diet versus gastric bypass surgery in people with diabetes results in divergent brain activation patterns: an functional MRI study, Diabetes Care, Vol: 44, Pages: 1842-1851, ISSN: 0149-5992
OBJECTIVE: Weight loss achieved with very-low-calorie diets (VLCDs) can produce remission of type 2 diabetes (T2D), but weight regain very often occurs with reintroduction of higher calorie intakes. In contrast, bariatric surgery produces clinically significant and durable weight loss, with diabetes remission that translates into reductions in mortality. We hypothesized that in patients living with obesity and prediabetes/T2D, longitudinal changes in brain activity in response to food cues as measured using functional MRI would explain this difference.RESEARCH DESIGN AND METHODS: Sixteen participants underwent gastric bypass surgery, and 19 matched participants undertook a VLCD (meal replacement) for 4 weeks. Brain responses to food cues and resting-state functional connectivity were assessed with functional MRI pre- and postintervention and compared across groups.RESULTS: We show that Roux-en-Y gastric bypass surgery (RYGB) results in three divergent brain responses compared with VLCD-induced weight loss: 1) VLCD resulted in increased brain reward center food cue responsiveness, whereas in RYGB, this was reduced; 2) VLCD resulted in higher neural activation of cognitive control regions in response to food cues associated with exercising increased cognitive restraint over eating, whereas RYGB did not; and 3) a homeostatic appetitive system (centered on the hypothalamus) is better engaged following RYGB-induced weight loss than VLCD.CONCLUSIONS: Taken together, these findings point to divergent brain responses to different methods of weight loss in patients with diabetes, which may explain weight regain after a short-term VLCD in contrast to enduring weight loss after RYGB.
McGlone ER, Manchanda Y, Jones B, et al., 2021, Receptor Activity-Modifying Protein 2 (RAMP2) alters glucagon receptor trafficking in hepatocytes with functional effects on receptor signalling
<jats:title>Abstract</jats:title><jats:sec><jats:title>Objectives</jats:title><jats:p>Receptor Activity-Modifying Protein 2 (RAMP2) is a chaperone protein which allosterically binds to and interacts with the glucagon receptor (GCGR). The aims of this study were to investigate the effects of RAMP2 on GCGR trafficking and signalling in the liver, where glucagon is important for carbohydrate and lipid metabolism.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Subcellular localisation of GCGR in the presence and absence of RAMP2 was investigated using confocal microscopy, trafficking assays and radioligand binding assays in human embryonic kidney (HEK293T) and human hepatoma (Huh7) cells. Mouse embryonic fibroblasts (MEFs) lacking Wiskott Aldrich Syndrome protein and scar homologue (WASH) complex were used to investigate the effect of a halt in recycling of internalised proteins on GCGR signalling in the absence of RAMP2. NanoBiT complementation and cyclic AMP assays were used to study the functional effect of RAMP2 on recruitment and activation of GCGR signalling mediators. Response to hepatic RAMP2 up-regulation in lean and obese adult mice using a bespoke adeno-associated viral vector was also studied.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>GCGR is predominantly localised at the plasma membrane in the absence of RAMP2 and exhibits remarkably slow internalisation in response to agonist stimulation. Rapid intracellular retention of glucagon-stimulated GCGR in cells lacking WASH complex indicates that activated GCGRs undergo continuous cycles of internalisation and recycling despite apparent GCGR plasma membrane localisation up to 40 minutes post-stimulation. Co-expression of RAMP2 induces GCGR internalisation both basally and in response to agonist-stimulation. The intracellular retention of GCGR in the presence
Wakeman R, Ainley R, Arnott ID, et al., 2021, IBD care in the UK: A comprehensive, novel service assessment with feedback from 10,222 patients and 166 NHS organisations to inform a vision for quality improvement, Publisher: OXFORD UNIV PRESS, Pages: S220-S220, ISSN: 1873-9946
Tan TM-M, Minnion J, Khoo B, et al., 2021, Safety and efficacy of an extended-release peptide YY analogue for obesity: A randomized, placebo-controlled, phase 1 trial, Diabetes, Obesity and Metabolism: a journal of pharmacology and therapeutics, Vol: 23, Pages: 1471-1483, ISSN: 1462-8902
AimTo report the results from a Phase 1 trial of an extended-release peptide YY analogue, Y14, developed for the treatment of obesity.MethodsY14 was evaluated in overweight/obese volunteers in a Phase 1 randomized placebo-controlled trial, conducted in a clinical trial unit in the United Kingdom. Part A was a blinded single-ascending-dose study evaluating doses up to 36 mg. Part B was double-blinded and tested multiple ascending doses between 9 and 36 mg, given at 7- to 14-day intervals, over the course of 28 days, with up to five doses given per participant. The primary outcome was safety and tolerability; the secondary outcome was assessment of pharmacokinetic (PK) characteristics. Exploratory outcomes included food intake, body weight change and glucose tolerance after multiple doses.ResultsBetween April 11, 2017 and December 24, 2018, 53 participants were enrolled into Part A and 24 into Part B of the trial. The PK characteristics were compatible with administration every 7 to 14 days. The most common adverse events (AEs) were nausea, vomiting or administration site reactions, which were mild in most cases and settled with time. No serious AE occurred. Participants given multiple doses of Y14 lost between −2.87 and −3.58 kg body weight compared with placebo (P <0.0001) at 31 days from the first dose, with profound reductions in food intake of 38% to 55% (P <0.0001, compared to placebo) and there was no evidence of tachyphylaxis.ConclusionsOur results support the continued development of Y14 as a novel treatment for obesity.
Miras AD, Kamocka A, Tan T, et al., 2021, Long limb compared with standard limb Roux-en-Y gastric bypass for type 2 diabetes and obesity: the LONG LIMB RCT, Efficacy and Mechanism Evaluation, Vol: 8, ISSN: 2050-4365
BackgroundRoux-en-Y gastric bypass is recognised as a standard of care in the treatment of diabetes mellitus and obesity. However, the optimal length of the Roux-en-Y gastric bypass limbs remains controversial, with substantial variation in practice. Specifically, a longer biliopancreatic limb length of 150 cm (‘long limb’) has been hypothesised to be better for the treatment of diabetes mellitus because it increases the postprandial secretion of gut hormones, such as glucagon-like peptide 1, and increases insulin sensitivity, compared with the Roux-en-Y gastric bypass utilising a standard biliopancreatic limb length of 50 cm (‘standard limb’).ObjectiveTo evaluate the mechanisms, clinical efficacy and safety of long limb versus the standard limb Roux-en-Y gastric bypass in patients undergoing metabolic surgery for obesity and diabetes mellitus.DesignA double-blind, mechanistic randomised controlled trial was conducted to evaluate the mechanisms, clinical efficacy and safety of the two interventions.SettingImperial College London, King’s College London and their associated NHS trusts.ParticipantsPatients with obesity and type 2 diabetes mellitus who were eligible for metabolic surgery.InterventionsParticipants were randomly assigned (1 : 1) to 150-cm (long limb) or 50-cm (standard limb) biliopancreatic limb Roux-en-Y gastric bypass with a fixed alimentary limb of 100 cm. The participants underwent meal tolerance tests to measure glucose excursions, glucagon-like peptide 1 and insulin secretion, and hyperinsulinaemic–euglycaemic clamps with stable isotopes to measure insulin sensitivity preoperatively, at 2 weeks after the surgery and at matched 20% total body weight loss. Clinical follow-up continued up to 1 year.Main outcome measuresPrimary – postprandial peak of active glucagon-like peptide 1 concentration at 2 weeks after intervention. Secondary – fasting and postprandial glucose an
Kenkre J, Ahmed A, Purkayastha S, et al., 2021, Who will benefit from bariatric surgery for diabetes? A protocol for an observational cohort study, BMJ Open, Vol: 11, ISSN: 2044-6055
Introduction Type 2 diabetes mellitus (T2DM) and obesity are pandemic diseases that lead to a great deal of morbidity and mortality. The most effective treatment for obesity and T2DM is bariatric or metabolic surgery; it can lead to long-term diabetes remission with 4 in 10 of those undergoing surgery having normal blood glucose on no medication 1 year postoperatively. However, surgery carries risks and, additionally, due to resource limitations, there is a restricted number of patients who can access this treatment. Moreover, not all those who undertake surgery respond equally well metabolically. The objective of the current research is to prospectively investigate predictors of T2DM response following metabolic surgery, including those directly involved in its aetiopathogenesis such as fat distribution and genetic variants. This will inform development of a clinically applicable model to help prioritise this therapy to those predicted to have remission.Methods and analysis A prospective multicentre observational cohort study of adult patients with T2DM and obesity undergoing Roux-en-Y gastric bypass surgery. Patients will be comprehensively assessed before surgery to determine their clinical, metabolic, psychological, genetic and fat distribution profiles. A multivariate logistic regression model will be used to assess the value of the factors derived from the preoperative assessment in terms of prediction of diabetes remission.Ethics and dissemination Formal ethics review was undertaken with a favourable opinion (UK HRA RES reference number 18/LO/0931). The dissemination plan is to present the results at conferences, in peer-reviewed journals as well as to lay media and to patient organisations.Trial registration details ClinicalTrials.gov, Identifier: NCT03842475.
Miras A, Kamocka A, Pérez-Pevida B, et al., 2021, The effect of standard versus longer intestinal bypass on GLP-1 regulation and glucose metabolism in patients with type 2 diabetes undergoing roux-en-Y gastric bypass. The long-limb study, Diabetes Care, Vol: 44, Pages: 1-9, ISSN: 0149-5992
ObjectiveRoux-en-Y gastric bypass (RYGB) characteristically enhances post-prandial levels of Glucagon-like peptide 1 (GLP-1), a mechanism that contributes to its profound glucose-lowering effects. This enhancement is thought to be triggered by bypass of food to the distal small intestine with higher densities of neuroendocrine L-cells. We hypothesised that if this is the predominant mechanism behind the enhanced secretion of GLP-1, a longer intestinal bypass would potentiate the post-prandial peak in GLP-1, translating into higher insulin secretion and thus additional improvements in glucose tolerance. To investigate this, we conducted a mechanistic study comparing two variants of RYGB that differ in the length of intestinal bypass.Research Design and MethodsFifty-three patients with type 2 diabetes and obesity were randomised to either ‘standard limb’ RYGB (50cm biliopancreatic limb) or ‘long limb’ RYGB (150cm biliopancreatic limb). They underwent measurements of GLP-1 and insulin secretion following a mixed meal and insulin sensitivity using euglycaemic hyperinsulinaemic clamps at baseline, 2 weeks and at 20% weight loss after surgery.ResultsBoth groups exhibited enhancement in post-prandial GLP-1 secretion and improvements in glycaemia compared to baseline. There were no significant differences in post-prandial peak concentrations of GLP-1, time to peak, insulin secretion, and insulin sensitivity. ConclusionThe findings of this study demonstrate that lengthening of the intestinal bypass in RYGB does not affect GLP-1 secretion. Thus, the characteristic enhancement of GLP-1 response after RYGB might not depend on delivery of nutrients to more distal intestinal segments.
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