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Pálsson TG, Gilliam-Vigh H, Jensen BAH, Jeppesen PB, Lund AB, Knop FK, Nielsen CK. Targeting the GLP-2 receptor in the management of obesity. Peptides 2024; 177:171210. [PMID: 38579917 DOI: 10.1016/j.peptides.2024.171210] [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: 12/22/2023] [Revised: 03/27/2024] [Accepted: 04/01/2024] [Indexed: 04/07/2024]
Abstract
Recent advancements in understanding glucagon-like peptide 2 (GLP-2) biology and pharmacology have sparked interest in targeting the GLP-2 receptor (GLP-2R) in the treatment of obesity. GLP-2 is a proglucagon-derived 33-amino acid peptide co-secreted from enteroendocrine L cells along with glucagon-like peptide 1 (GLP-1) and has a range of actions via the GLP-2R, which is particularly expressed in the gastrointestinal tract, the liver, adipose tissue, and the central nervous system (CNS). In humans, GLP-2 evidently induces intestinotrophic effects (i.e., induction of intestinal mucosal proliferation and improved gut barrier function) and promotes mesenteric blood flow. However, GLP-2 does not seem to have appetite or food intake-reducing effects in humans, but its gut barrier-promoting effect may be of interest in the context of obesity. Obesity is associated with reduced gut barrier function, increasing the translocation of proinflammatory gut content to the circulation. This phenomenon constitutes a strong driver of obesity-associated systemic low-grade inflammation, which in turn plays a major role in the development of most obesity-associated complications. Thus, the intestinotrophic and gut barrier-improving effect of GLP-2, which in obese rodent models shows strong anti-inflammatory potential, may, in combination with food intake-reducing strategies, e.g., GLP-1 receptor (GLP-1) agonism, be able to rectify core pathophysiological mechanism of obesity. Here, we provide an overview of GLP-2 physiology in the context of obesity pathophysiology and review the pharmacological potential of GLP-2R activation in the management of obesity and related comorbidities.
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Affiliation(s)
- Thorir G Pálsson
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark
| | - Hannah Gilliam-Vigh
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark
| | - Benjamin A H Jensen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Palle B Jeppesen
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Intestinal Failure and Liver Diseases, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Asger B Lund
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark; Steno Diabetes Center Copenhagen, Copenhagen University Hospital, Herlev, Denmark
| | - Filip K Knop
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark; Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Steno Diabetes Center Copenhagen, Copenhagen University Hospital, Herlev, Denmark
| | - Casper K Nielsen
- Center for Clinical Metabolic Research, Copenhagen University Hospital - Herlev and Gentofte, Hellerup, Denmark.
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2
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Fauste E, Panadero MI, Pérez-Armas M, Donis C, López-Laiz P, Sevillano J, Sánchez-Alonso MG, Ramos-Álvarez MP, Otero P, Bocos C. Maternal fructose intake aggravates the harmful effects of a Western diet in rat male descendants impacting their cholesterol metabolism. Food Funct 2024; 15:6147-6163. [PMID: 38767501 DOI: 10.1039/d4fo01466a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Scope: fructose consumption from added sugars correlates with the epidemic rise in MetS and CVD. Maternal fructose intake has been described to program metabolic diseases in progeny. However, consumption of fructose-containing beverages is allowed during gestation. Cholesterol is also a well-known risk factor for CVD. Therefore, it is essential to study Western diets which combine fructose and cholesterol and how maternal fructose can influence the response of progeny to these diets. Methods and results: a high-cholesterol (2%) diet combined with liquid fructose (10%), as a model of an unhealthy Western diet, was administered to descendants from control and fructose-fed mothers. Gene (mRNA and protein) expression and plasma, fecal and tissue parameters of cholesterol metabolism were measured. Interestingly, progeny from fructose-fed dams consumed less liquid fructose and cholesterol-rich chow than males from control mothers. Moreover, descendants of fructose-fed mothers fed a Western diet showed an increased cholesterol elimination through bile and feces than males from control mothers. Despite these mitigating circumstances to develop a proatherogenic profile, the same degree of hypercholesterolemia and severity of steatosis were observed in all descendants fed a Western diet, independently of maternal intake. An increased intestinal absorption of cholesterol, synthesis, esterification, and assembly into lipoprotein found in males from fructose-fed dams consuming a Western diet could be the cause. Moreover, an augmented GLP2 signalling seen in these animals would explain this enhanced lipid absorption. Conclusions: maternal fructose intake, through a fetal programming, makes a Western diet considerably more harmful in their descendants than in the offspring from control mothers.
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Affiliation(s)
- E Fauste
- Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Montepríncipe, Boadilla del Monte, Madrid, Spain.
| | - M I Panadero
- Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Montepríncipe, Boadilla del Monte, Madrid, Spain.
| | - M Pérez-Armas
- Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Montepríncipe, Boadilla del Monte, Madrid, Spain.
| | - C Donis
- Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Montepríncipe, Boadilla del Monte, Madrid, Spain.
| | - P López-Laiz
- Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Montepríncipe, Boadilla del Monte, Madrid, Spain.
| | - J Sevillano
- Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Montepríncipe, Boadilla del Monte, Madrid, Spain.
| | - M G Sánchez-Alonso
- Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Montepríncipe, Boadilla del Monte, Madrid, Spain.
| | - M P Ramos-Álvarez
- Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Montepríncipe, Boadilla del Monte, Madrid, Spain.
| | - P Otero
- Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Montepríncipe, Boadilla del Monte, Madrid, Spain.
| | - C Bocos
- Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Montepríncipe, Boadilla del Monte, Madrid, Spain.
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3
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Mukherjee K, Xiao C. GLP-2 regulation of intestinal lipid handling. Front Physiol 2024; 15:1358625. [PMID: 38426205 PMCID: PMC10902918 DOI: 10.3389/fphys.2024.1358625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 01/31/2024] [Indexed: 03/02/2024] Open
Abstract
Lipid handling in the intestine is important for maintaining energy homeostasis and overall health. Mishandling of lipids in the intestine contributes to dyslipidemia and atherosclerotic cardiovascular diseases. Despite advances in this field over the past few decades, significant gaps remain. The gut hormone glucagon-like peptide-2 (GLP-2) has been shown to play pleotropic roles in the regulation of lipid handling in the intestine. Of note, GLP-2 exhibits unique actions on post-prandial lipid absorption and post-absorptive release of intestinally stored lipids. This review aims to summarize current knowledge in how GLP-2 regulates lipid processing in the intestine. Elucidating the mechanisms of GLP-2 regulation of intestinal lipid handling not only improves our understanding of GLP-2 biology, but also provides insights into how lipids are processed in the intestine, which offers opportunities for developing novel strategies towards prevention and treatment of dyslipidemia and atherosclerotic cardiovascular diseases.
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Affiliation(s)
| | - Changting Xiao
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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4
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Mukherjee K, Wang R, Xiao C. Release of Lipids Stored in the Intestine by Glucagon-Like Peptide-2 Involves a Gut-Brain Neural Pathway. Arterioscler Thromb Vasc Biol 2024; 44:192-201. [PMID: 37970717 DOI: 10.1161/atvbaha.123.320032] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Accepted: 11/07/2023] [Indexed: 11/17/2023]
Abstract
BACKGROUND The gut hormone GLP-2 (glucagon-like peptide-2) plays important roles in lipid handling in the intestine. During postabsorptive stage, it releases preformed chylomicrons stored in the intestine, the underlying mechanisms of which are not well understood. Previous studies implicate the involvement of neural pathways in GLP-2's actions on lipid absorption in the intestine, but the role of such mechanisms in releasing postabsorptive lipid storage has not been established. METHODS Here, in mesenteric lymph duct cannulated rats, we directly tested whether gut-brain neural communication mediates GLP-2's effects on postabsorptive lipid mobilization in the intestine. We performed total subdiaphragmatic vagotomy to disrupt the gut-brain neural communication and analyzed lipid output 5 hours after a lipid load in response to intraperitoneal GLP-2 or saline. RESULTS Peripheral GLP-2 administration led to increased lymph lipid output and activation of proopiomelanocortin neurons in the arcuate nucleus of hypothalamus. Disruption of gut-brain neural communication via vagotomy blunted GLP-2's effects on promoting lipid release in the intestine. CONCLUSIONS These results, for the first time, demonstrate a novel mechanism in which postabsorptive mobilization of intestinal lipid storage by GLP-2 enlists a gut-brain neural pathway.
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Affiliation(s)
- Kundanika Mukherjee
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Rita Wang
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Changting Xiao
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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Abstract
Postprandial hyperlipidaemia is an important feature of diabetic dyslipidaemia and plays an important role in the development of cardiovascular disease in individuals with type 2 diabetes. Postprandial hyperlipidaemia in type 2 diabetes is secondary to increased chylomicron production by the enterocytes and delayed catabolism of chylomicrons and chylomicron remnants. Insulin and some intestinal hormones (e.g. glucagon-like peptide-1 [GLP-1]) influence intestinal lipid metabolism. In individuals with type 2 diabetes, insulin resistance and possibly reduced GLP-1 secretion are involved in the pathophysiology of postprandial hyperlipidaemia. Several factors are involved in the overproduction of chylomicrons: (1) increased expression of microsomal triglyceride transfer protein, which is a key enzyme in chylomicron synthesis; (2) higher stability and availability of apolipoprotein B-48; and (3) increased de novo lipogenesis. Individuals with type 2 diabetes present with disorders of cholesterol metabolism in the enterocytes with reduced absorption and increased synthesis. The increased production of chylomicrons in type 2 diabetes is also associated with a reduction in their catabolism, mostly because of a reduction in activity of lipoprotein lipase. Modification of the microbiota, which is observed in type 2 diabetes, may also generate disorders of intestinal lipid metabolism, but human data remain limited. Some glucose-lowering treatments significantly influence intestinal lipid absorption and transport. Postprandial hyperlipidaemia is reduced by metformin, pioglitazone, alpha-glucosidase inhibitors, dipeptidyl peptidase 4 inhibitors and GLP-1 agonists. The most pronounced effect is observed with GLP-1 agonists, which reduce chylomicron production significantly in individuals with type 2 diabetes and have a direct effect on the intestine by reducing the expression of genes involved in intestinal lipoprotein metabolism. The effect of sodium-glucose cotransporter 2 inhibitors on intestinal lipid metabolism needs to be clarified.
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Affiliation(s)
- Bruno Vergès
- Endocrinology-Diabetology Department, University-Hospital, Dijon, France.
- Inserm UMR 1231, Medical School, University of Burgundy-Franche Comté, Dijon, France.
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Grande EM, Raka F, Hoffman S, Adeli K. GLP-2 Regulation of Dietary Fat Absorption and Intestinal Chylomicron Production via Neuronal Nitric Oxide Synthase (nNOS) Signaling. Diabetes 2022; 71:1388-1399. [PMID: 35476805 DOI: 10.2337/db21-1053] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 04/17/2022] [Indexed: 11/13/2022]
Abstract
Postprandial dyslipidemia is a metabolic condition commonly associated with insulin-resistant states, such as obesity and type 2 diabetes. It is characterized by the overproduction of intestinal chylomicron particles and excess atherogenic chylomicron remnants in circulation. We have previously shown that glucagon-like peptide 2 (GLP-2) augments dietary fat uptake and chylomicron production in insulin-resistant states; however, the underlying mechanisms remain unclear. Previous studies have implicated nitric oxide (NO) in the absorptive actions of GLP-2. In this study, we report a novel role for neuronal NO synthase (nNOS)-mediated NO generation in lipid uptake and chylomicron formation based on studies in C57BL/6J mice, nNOS-/- mice, and Syrian golden hamsters after intraduodenal and oral fat administration. GLP-2 treatment in wild-type (WT) mice significantly increased postprandial lipid accumulation and circulating apolipoprotein B48 protein levels, while these effects were abolished in nNOS-/- mice. nNOS inhibition in Syrian golden hamsters and protein kinase G (PKG) inhibition in WT mice also abrogated the effect of GLP-2 on postprandial lipid accumulation. These studies demonstrate a novel mechanism in which nNOS-generated NO is crucial for GLP-2-mediated lipid absorption and chylomicron production in both mouse and hamster models. Overall, our data implicate an nNOS-PKG-mediated pathway in GLP-2-mediated stimulation of dietary fat absorption and intestinal chylomicron production.
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Affiliation(s)
- Elisabeth M Grande
- Molecular Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Fitore Raka
- Molecular Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Simon Hoffman
- Molecular Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Khosrow Adeli
- Molecular Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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7
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Abstract
PURPOSE OF REVIEW Lymphatics are known to have active, regulated pumping by smooth muscle cells that enhance lymph flow, but whether active regulation of lymphatic pumping contributes significantly to the rate of appearance of chylomicrons (CMs) in the blood circulation (i.e., CM production rate) is not currently known. In this review, we highlight some of the potential mechanisms by which lymphatics may regulate CM production. RECENT FINDINGS Recent data from our lab and others are beginning to provide clues that suggest a more active role of lymphatics in regulating CM appearance in the circulation through various mechanisms. Potential contributors include apolipoproteins, glucose, glucagon-like peptide-2, and vascular endothelial growth factor-C, but there are likely to be many more. SUMMARY The digested products of dietary fats absorbed by the small intestine are re-esterified and packaged by enterocytes into large, triglyceride-rich CM particles or stored temporarily in intracellular cytoplasmic lipid droplets. Secreted CMs traverse the lamina propria and are transported via lymphatics and then the blood circulation to liver and extrahepatic tissues, where they are stored or metabolized as a rich energy source. Although indirect data suggest a relationship between lymphatic pumping and CM production, this concept requires more experimental evidence before we can be sure that lymphatic pumping contributes significantly to the rate of CM appearance in the blood circulation.
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Affiliation(s)
- Majid M Syed-Abdul
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Lili Tian
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Changting Xiao
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Gary F Lewis
- Departments of Medicine and Physiology and Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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8
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Stahel P, Xiao C, Nahmias A, Tian L, Lewis GF. Multi-organ Coordination of Lipoprotein Secretion by Hormones, Nutrients and Neural Networks. Endocr Rev 2021; 42:815-838. [PMID: 33743013 PMCID: PMC8599201 DOI: 10.1210/endrev/bnab008] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Indexed: 12/15/2022]
Abstract
Plasma triglyceride-rich lipoproteins (TRL), particularly atherogenic remnant lipoproteins, contribute to atherosclerotic cardiovascular disease. Hypertriglyceridemia may arise in part from hypersecretion of TRLs by the liver and intestine. Here we focus on the complex network of hormonal, nutritional, and neuronal interorgan communication that regulates secretion of TRLs and provide our perspective on the relative importance of these factors. Hormones and peptides originating from the pancreas (insulin, glucagon), gut [glucagon-like peptide 1 (GLP-1) and 2 (GLP-2), ghrelin, cholecystokinin (CCK), peptide YY], adipose tissue (leptin, adiponectin) and brain (GLP-1) modulate TRL secretion by receptor-mediated responses and indirectly via neural networks. In addition, the gut microbiome and bile acids influence lipoprotein secretion in humans and animal models. Several nutritional factors modulate hepatic lipoprotein secretion through effects on the central nervous system. Vagal afferent signaling from the gut to the brain and efferent signals from the brain to the liver and gut are modulated by hormonal and nutritional factors to influence TRL secretion. Some of these factors have been extensively studied and shown to have robust regulatory effects whereas others are "emerging" regulators, whose significance remains to be determined. The quantitative importance of these factors relative to one another and relative to the key regulatory role of lipid availability remains largely unknown. Our understanding of the complex interorgan regulation of TRL secretion is rapidly evolving to appreciate the extensive hormonal, nutritional, and neural signals emanating not only from gut and liver but also from the brain, pancreas, and adipose tissue.
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Affiliation(s)
- Priska Stahel
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Changting Xiao
- Department of Anatomy, Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Avital Nahmias
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Lili Tian
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Gary Franklin Lewis
- Division of Endocrinology and Metabolism, Departments of Medicine and Physiology, Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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Markovic MA, Srikrishnaraj A, Tsang D, Brubaker PL. Requirement for the intestinal epithelial insulin-like growth factor-1 receptor in the intestinal responses to glucagon-like peptide-2 and dietary fat. FASEB J 2020; 34:6628-6640. [PMID: 32212202 DOI: 10.1096/fj.202000169r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/28/2020] [Accepted: 03/10/2020] [Indexed: 12/13/2022]
Abstract
The intestinal hormone, glucagon-like peptide-2 (GLP-2), enhances the enterocyte chylomicron production. However, GLP-2 is known to require the intestinal-epithelial insulin-like growth factor-1 receptor (IE-IGF-1R) for its other actions to increase intestinal growth and barrier function. The role of the IE-IGF-1R in enterocyte lipid handling was thus tested in the GLP-2 signaling pathway, as well as in response to a Western diet (WD). IE-IGF-1R knockout (KO) and control mice were treated for 11 days with h(GLY2 )GLP-2 or fed a WD for 18 weeks followed by a duodenal fat tolerance test with C14 -labeled triolein. Human Caco-2BBE cells were treated with an IGF-1R antagonist or signaling inhibitors to determine triglyceride-associated protein expression. The IE-IGF-1R was required for GLP-2-induced increases in CD36 and FATP-4 in chow-fed mice, and for expression in vitro; FATP-4 also required PI3K/Akt. Although WD-fed IE-IGF-1R KO mice demonstrated normal CD36 expression, the protein was incorrectly localized 2h post-duodenal fat administration. IE-IGF-1R KO also prevented the WD-induced increase in MTP and decrease in APOC3, increased jejunal mucosal C14 -fat accumulation, and elevated plasma triglyceride and C14 -fat levels. Collectively, these studies elucidate new roles for the IE-IGF-1R in enterocyte lipid handling, under basal conditions and in response to GLP-2 and WD-feeding.
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Affiliation(s)
| | | | - Derek Tsang
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Patricia L Brubaker
- Department of Physiology, University of Toronto, Toronto, ON, Canada.,Department of Medicine, University of Toronto, Toronto, ON, Canada
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10
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Orliaguet L, Dalmas E, Drareni K, Venteclef N, Alzaid F. Mechanisms of Macrophage Polarization in Insulin Signaling and Sensitivity. Front Endocrinol (Lausanne) 2020; 11:62. [PMID: 32140136 PMCID: PMC7042402 DOI: 10.3389/fendo.2020.00062] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 01/30/2020] [Indexed: 12/11/2022] Open
Abstract
Type-2 diabetes (T2D) is a disease of two etiologies: metabolic and inflammatory. At the cross-section of these etiologies lays the phenomenon of metabolic inflammation. Whilst metabolic inflammation is characterized as systemic, a common starting point is the tissue-resident macrophage, who's successful physiological or aberrant pathological adaptation to its microenvironment determines disease course and severity. This review will highlight the key mechanisms in macrophage polarization, inflammatory and non-inflammatory signaling that dictates the development and progression of insulin resistance and T2D. We first describe the known homeostatic functions of tissue macrophages in insulin secreting and major insulin sensitive tissues. Importantly we highlight the known mechanisms of aberrant macrophage activation in these tissues and the ways in which this leads to impairment of insulin sensitivity/secretion and the development of T2D. We next describe the cellular mechanisms that are known to dictate macrophage polarization. We review recent progress in macrophage bio-energetics, an emerging field of research that places cellular metabolism at the center of immune-effector function. Importantly, following the advent of the metabolically-activated macrophage, we cover the known transcriptional and epigenetic factors that canonically and non-canonically dictate macrophage differentiation and inflammatory polarization. In closing perspectives, we discuss emerging research themes and highlight novel non-inflammatory or non-immune roles that tissue macrophages have in maintaining microenvironmental and systemic homeostasis.
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Affiliation(s)
- Lucie Orliaguet
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, Paris, France
| | - Elise Dalmas
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, Paris, France
| | - Karima Drareni
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, Paris, France
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA, United States
| | - Nicolas Venteclef
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, Paris, France
| | - Fawaz Alzaid
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, USPC, Université Paris Descartes, Université Paris Diderot, Paris, France
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11
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Xiao C, Stahel P, Nahmias A, Lewis GF. Emerging Role of Lymphatics in the Regulation of Intestinal Lipid Mobilization. Front Physiol 2020; 10:1604. [PMID: 32063861 PMCID: PMC7000543 DOI: 10.3389/fphys.2019.01604] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 12/20/2019] [Indexed: 12/21/2022] Open
Abstract
Intestinal handling of dietary triglycerides has important implications for health and disease. Following digestion in the intestinal lumen, absorption, and re-esterification of fatty acids and monoacylglycerols in intestinal enterocytes, triglycerides are packaged into lipoprotein particles (chylomicrons) for secretion or into cytoplasmic lipid droplets for transient or more prolonged storage. Despite the recognition of prolonged retention of triglycerides in the post-absorptive phase and subsequent release from the intestine in chylomicron particles, the underlying regulatory mechanisms remain poorly understood. Chylomicron secretion involves multiple steps, including intracellular assembly and post-assembly transport through cellular organelles, the lamina propria, and the mesenteric lymphatics before being released into the circulation. Contrary to the long-held view that the intestinal lymphatic vasculature acts mainly as a passive conduit, it is increasingly recognized to play an active and regulatory role in the rate of chylomicron release into the circulation. Here, we review the latest advances in understanding the role of lymphatics in intestinal lipid handling and chylomicron secretion. We highlight emerging evidence that oral glucose and the gut hormone glucagon-like peptide-2 mobilize retained enteral lipid by differing mechanisms to promote the secretion of chylomicrons via glucose possibly by mobilizing cytoplasmic lipid droplets and via glucagon-like peptide-2 possibly by targeting post-enterocyte secretory mechanisms. We discuss other potential regulatory factors that are the focus of ongoing and future research. Regulation of lymphatic pumping and function is emerging as an area of great interest in our understanding of the integrated absorption of dietary fat and chylomicron secretion and potential implications for whole-body metabolic health.
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Affiliation(s)
- Changting Xiao
- Department of Medicine and Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Priska Stahel
- Department of Medicine and Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Avital Nahmias
- Department of Medicine and Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Gary F Lewis
- Department of Medicine and Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
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