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Bailey CJ, Flatt PR. Duodenal enteroendocrine cells and GIP as treatment targets for obesity and type 2 diabetes. Peptides 2024; 174:171168. [PMID: 38320643 DOI: 10.1016/j.peptides.2024.171168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Revised: 02/02/2024] [Accepted: 02/02/2024] [Indexed: 02/08/2024]
Abstract
The duodenum is an important source of endocrine and paracrine signals controlling digestion and nutrient disposition, notably including the main incretin hormone glucose-dependent insulinotropic polypeptide (GIP). Bariatric procedures that prevent nutrients from contact with the duodenal mucosa are particularly effective interventions to reduce body weight and improve glycaemic control in obesity and type 2 diabetes. These procedures take advantage of increased nutrient delivery to more distal regions of the intestine which enhances secretion of the other incretin hormone glucagon-like peptide-1 (GLP-1). Preclinical experiments have shown that either an increase or a decrease in the secretion or action of GIP can decrease body weight and blood glucose in obesity and non-insulin dependent hyperglycaemia, but clinical studies involving administration of GIP have been inconclusive. However, a synthetic dual agonist peptide (tirzepatide) that exerts agonism at receptors for GIP and GLP-1 has produced marked weight-lowering and glucose-lowering effects in people with obesity and type 2 diabetes. This appears to result from chronic biased agonism in which the novel conformation of the peptide triggers enhanced signalling by the GLP-1 receptor through reduced internalisation while reducing signalling by the GIP receptor directly or via functional antagonism through increased internalisation and degradation.
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Affiliation(s)
| | - Peter R Flatt
- Diabetes Research Centre, School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA Northern Ireland, UK
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Flatt PR, Bailey CJ. Vincent Marks (10 June 1930 to 6 November 2023). Diabet Med 2024; 41:e15274. [PMID: 38130163 DOI: 10.1111/dme.15274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 12/09/2023] [Indexed: 12/23/2023]
Affiliation(s)
- Peter R Flatt
- School of Biomedical Sciences, Ulster University, Coleraine, UK
| | - Clifford J Bailey
- School of Life and Health Sciences, Aston University, Birmingham, UK
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Flatt PR. Vincent Marks (10 June 1930-6 November 2023) A personal appreciation by Peter R. Flatt. Peptides 2024; 171:171119. [PMID: 38029969 DOI: 10.1016/j.peptides.2023.171119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Affiliation(s)
- Peter R Flatt
- School of Biomedical Sciences, Ulster University, Coleraine, Northern Ireland, UK
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Boer GA, Hay DL, Tups A. Obesity pharmacotherapy: incretin action in the central nervous system. Trends Pharmacol Sci 2023; 44:50-63. [PMID: 36462999 DOI: 10.1016/j.tips.2022.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/02/2022] [Accepted: 11/08/2022] [Indexed: 12/02/2022]
Abstract
The prevalence of obesity is rising, creating an urgent need for efficacious therapies. Recent clinical trials show that tirzepatide, a dual agonist of receptors for the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), yields more weight loss than selective GLP-1 receptor (GLP-1R) agonists. Incretin receptors in the central nervous system (CNS) may contribute to these effects. Yet exactly how each receptor regulates body weight from within the CNS is not clearly understood. It remains especially unclear how GIP receptor (GIPR) signalling contributes to the effects of tirzepatide because both stimulation and inhibition of CNS GIPRs yield weight loss in preclinical models. We summarise current knowledge on CNS incretin receptor pharmacology to provide insight into the potential mechanisms of action of dual GIPR/GLP-1R agonists, with tirzepatide as the exemplar. In addition, we discuss recent developments in incretin-based dual- and tri-agonism for inducing weight loss in obese individuals.
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Affiliation(s)
- Geke Aline Boer
- Centre for Neuroendocrinology, Department of Physiology, University of Otago, Otago, New Zealand
| | - Debbie L Hay
- Department of Pharmacology and Toxicology, University of Otago, Otago, New Zealand; Maurice Wilkins Centre, Auckland, New Zealand
| | - Alexander Tups
- Centre for Neuroendocrinology, Department of Physiology, University of Otago, Otago, New Zealand; Maurice Wilkins Centre, Auckland, New Zealand.
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Zaffina I, Pelle MC, Armentaro G, Giofrè F, Cassano V, Sciacqua A, Arturi F. Effect of dual glucose-dependent insulinotropic peptide/glucagon-like peptide-1 receptor agonist on weight loss in subjects with obesity. Front Endocrinol (Lausanne) 2023; 14:1095753. [PMID: 36909312 PMCID: PMC9992880 DOI: 10.3389/fendo.2023.1095753] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 02/08/2023] [Indexed: 02/24/2023] Open
Abstract
The occurrence of obesity is an increasing issue worldwide, especially in industrialized countries. Weight loss is important both to treat obesity and to prevent the development of complications. Currently, several drugs are used to treat obesity, but their efficacy is modest. Thus, new anti-obesity treatments are needed. Recently, there has been increased interest in the development of incretins that combine body-weight-lowering and glucose-lowering effects. Therefore, a new drug that simultaneously coactivates both the glucose-dependent insulinotropic polypeptide (GIP) receptor (GIPR) and the glucagon-like peptide-1 receptor (GLP-1R) has been developed. Tirzepatide, the first in this class, improves glycemic control by increasing insulin sensitivity and lipid metabolism as well as by reducing body weight. Combining the activation of the two receptors, greater improvement of β-cell function offers more effective treatment of diabetes and obesity with fewer adverse effects than selective GLP-1R agonists. In the present review, we discuss the progress in the use of GIPR and GLP-1R coagonists and review literature from in vitro studies, animal studies, and human trials, highlighting the synergistic mechanisms of tirzepatide.
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Affiliation(s)
- Isabella Zaffina
- Unit of Internal Medicine, Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, Catanzaro, Italy
| | - Maria Chiara Pelle
- Unit of Internal Medicine, Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, Catanzaro, Italy
| | - Giuseppe Armentaro
- Geriatric Unit, Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, Catanzaro, Italy
| | - Federica Giofrè
- Unit of Internal Medicine, Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, Catanzaro, Italy
| | - Velia Cassano
- Geriatric Unit, Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, Catanzaro, Italy
| | - Angela Sciacqua
- Geriatric Unit, Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, Catanzaro, Italy
| | - Franco Arturi
- Unit of Internal Medicine, Department of Medical and Surgical Sciences, Magna Graecia University of Catanzaro, Catanzaro, Italy
- Research Centre for the Prevention and Treatment of Metabolic Diseases (CR METDIS), Magna Graecia University of Catanzaro, Catanzaro, Italy
- *Correspondence: Franco Arturi,
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Guccio N, Gribble FM, Reimann F. Glucose-Dependent Insulinotropic Polypeptide-A Postprandial Hormone with Unharnessed Metabolic Potential. Annu Rev Nutr 2022; 42:21-44. [PMID: 35609956 DOI: 10.1146/annurev-nutr-062320-113625] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Glucose-dependent insulinotropic polypeptide (GIP) is released from the upper small intestine in response to food intake and contributes to the postprandial control of nutrient disposition, including of sugars and fats. Long neglected as a potential therapeutic target, the GIPR axis has received increasing interest recently, with the emerging data demonstrating the metabolically favorable outcomes of adding GIPR agonism to GLP-1 receptor agonists in people with type 2 diabetes and obesity. This review examines the physiology of the GIP axis, from the mechanisms underlying GIP secretion from the intestine to its action on target tissues and therapeutic development. Expected final online publication date for the Annual Review of Nutrition, Volume 42 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Nunzio Guccio
- MRC Metabolic Diseases Unit, Wellcome Trust/MRC Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ,
| | - Fiona M Gribble
- MRC Metabolic Diseases Unit, Wellcome Trust/MRC Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ,
| | - Frank Reimann
- MRC Metabolic Diseases Unit, Wellcome Trust/MRC Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ,
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Conlon JM, O'Harte FPM, Flatt PR. Dual-agonist incretin peptides from fish with potential for obesity-related Type 2 diabetes therapy - A review. Peptides 2022; 147:170706. [PMID: 34861327 DOI: 10.1016/j.peptides.2021.170706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/28/2021] [Accepted: 11/29/2021] [Indexed: 12/25/2022]
Abstract
The long-acting glucagon-like peptide-1 receptor (GLP1R) agonist, semaglutide and the unimolecular glucose-dependent insulinotropic polypeptide receptor (GIPR)/GLP1R dual-agonist, tirzepatide have been successfully introduced as therapeutic options for patients with Type-2 diabetes (T2DM) and obesity. Proglucagon-derived peptides from phylogenetically ancient fish act as naturally occurring dual agonists at the GLP1R and the glucagon receptor (GCGR) with lamprey GLP-1 and paddlefish glucagon being the most potent and effective in stimulating insulin release from BRIN-BD11 clonal β-cells. These peptides were also the most effective in lowering blood glucose and elevating plasma insulin concentrations when administered intraperitoneally to overnight-fasted mice together with a glucose load. Zebrafish GIP acts as a dual agonist at the GIPR and GLP1R receptors. Studies with the high fat-fed mouse, an animal model with obesity, impaired glucose-tolerance and insulin-resistance, have shown that twice-daily administration of the long-acting analogs [D-Ala2]palmitoyl-lamprey GLP-1 and [D-Ser2]palmitoyl-paddlefish glucagon over 21 days improves glucose tolerance and insulin sensitivity. This was associated with β-cell proliferation, protection of β-cells against apoptosis, decreased pancreatic glucagon content, improved lipid profile, reduced food intake and selective alteration in the expression of genes involved in β-cell stimulus-secretion coupling. In insulin-deficient GluCreERT2;ROSA26-eYFP transgenic mice, the peptides promoted an increase in β-cell mass with positive effects on transdifferentiation of glucagon-producing to insulin-producing cells. Naturally occurring fish dual agonist peptides, particularly lamprey GLP-1 and paddlefish glucagon, provide templates for development into therapeutic agents for obesity-related T2DM.
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Affiliation(s)
- J Michael Conlon
- Diabetes Research Group, School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK.
| | - Finbarr P M O'Harte
- Diabetes Research Group, School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK
| | - Peter R Flatt
- Diabetes Research Group, School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK
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Abstract
Glucose-dependent insulinotropic polypeptide (GIP) (also known as gastric inhibitory polypeptide) is a hormone produced in the upper gut and secreted to the circulation in response to the ingestion of foods, especially fatty foods. Growing evidence supports the physiological and pharmacological relevance of GIP in obesity. In an obesity setting, inhibition of endogenous GIP or its receptor leads to decreased energy intake, increased energy expenditure, or both, eventually causing weight loss. Further, supraphysiological dosing of exogenous long-lasting GIP agonists alters energy balance and has a marked antiobesity effect. This remarkable yet paradoxical antiobesity effect is suggested to occur primarily via the brain. The brain is capable of regulating both energy intake and expenditure and plays a critical role in human obesity. In addition, the GIP receptor is widely distributed throughout the brain, including areas responsible for energy homeostasis. Recent studies have uncovered previously underappreciated roles of the GIP receptor in the brain in the context of obesity. This article highlights how the GIP receptor expressed by the brain impacts obesity-related pathogenesis.
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Affiliation(s)
- Makoto Fukuda
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
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