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Li Y, Guo L. The versatile role of Serpina3c in physiological and pathological processes: a review of recent studies. Front Endocrinol (Lausanne) 2023; 14:1189007. [PMID: 37288300 PMCID: PMC10242157 DOI: 10.3389/fendo.2023.1189007] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Accepted: 05/10/2023] [Indexed: 06/09/2023] Open
Abstract
Murine Serpina3c belongs to the family of serine protease inhibitors (Serpins), clade "A" and its human homologue is SerpinA3. Serpina3c is involved in some physiological processes, including insulin secretion and adipogenesis. In the pathophysiological process, the deletion of Serpina3c leads to more severe metabolic disorders, such as aggravated non-alcoholic fatty liver disease (NAFLD), insulin resistance and obesity. In addition, Serpina3c can improve atherosclerosis and regulate cardiac remodeling after myocardial infarction. Many of these processes are directly or indirectly mediated by its inhibition of serine protease activity. Although its function has not been fully revealed, recent studies have shown its potential research value. Here, we aimed to summarize recent studies to provide a clearer view of the biological roles and the underlying mechanisms of Serpina3c.
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Tang C, Zhao H, Kong L, Meng F, Zhou L, Lu Z, Lu Y. Probiotic Yogurt Alleviates High-Fat Diet-Induced Lipid Accumulation and Insulin Resistance in Mice via the Adiponectin Pathway. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:1464-1476. [PMID: 36695046 DOI: 10.1021/acs.jafc.2c05670] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
A high-fat diet (HFD) easily contributes to the pathogenesis of obesity and insulin resistance. Obesity and insulin resistance have been clinical and public health challenges all over the world. Probiotic-fermented yogurt is one type of popular and functional beverage in people's daily lives. This study mainly explored the lipid- and glucose-lowering effects of Lactobacillus acidophilus NX2-6-fermented yogurt (LA-Y) in HFD-fed mice. The results showed that LA-Y administration improved the lipid profile in the serum and liver, reduced fasting blood glucose levels, and enhanced insulin sensitivity. Protein analysis showed that LA-Y treatment promoted fatty acid oxidation and suppressed de novo lipogenesis in the adipose tissue and liver. LA-Y effectively alleviated glucose metabolism disorders by activating the insulin signaling pathway, suppressing gluconeogenesis in the liver and muscle, reducing the concentration of pro-inflammatory cytokines in the serum, and promoting glycolysis and gluconeogenesis in the small intestine. LA-Y supplementation also promoted fat browning via the adiponectin/AMPKα/PGC-1α/UCP1 pathway and enhanced mitochondrial biogenesis in the liver and muscle by activating the adiponectin/AdipoR1/APPL1/AMPKα/PGC-1α pathway, leading to increased energy expenditure. Therefore, LA-Y may be a functional dairy food for preventing and alleviating diet-induced metabolic disorders.
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Affiliation(s)
- Chao Tang
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China
| | - Hongyuan Zhao
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China
| | - Liangyu Kong
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China
| | - Fanqiang Meng
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China
| | - Libang Zhou
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China
| | - Zhaoxin Lu
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China
| | - Yingjian Lu
- College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing 210023, Jiangsu Province, China
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Shibib L, Al-Qaisi M, Ahmed A, Miras AD, Nott D, Pelling M, Greenwald SE, Guess N. Reversal and Remission of T2DM - An Update for Practitioners. Vasc Health Risk Manag 2022; 18:417-443. [PMID: 35726218 PMCID: PMC9206440 DOI: 10.2147/vhrm.s345810] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 05/10/2022] [Indexed: 01/04/2023] Open
Abstract
Over the past 50 years, many countries around the world have faced an unchecked pandemic of obesity and type 2 diabetes (T2DM). As best practice treatment of T2DM has done very little to check its growth, the pandemic of diabesity now threatens to make health-care systems economically more difficult for governments and individuals to manage within their budgets. The conventional view has been that T2DM is irreversible and progressive. However, in 2016, the World Health Organization (WHO) global report on diabetes added for the first time a section on diabetes reversal and acknowledged that it could be achieved through a number of therapeutic approaches. Many studies indicate that diabetes reversal, and possibly even long-term remission, is achievable, belying the conventional view. However, T2DM reversal is not yet a standardized area of practice and some questions remain about long-term outcomes. Diabetes reversal through diet is not articulated or discussed as a first-line target (or even goal) of treatment by any internationally recognized guidelines, which are mostly silent on the topic beyond encouraging lifestyle interventions in general. This review paper examines all the sustainable, practical, and scalable approaches to T2DM reversal, highlighting the evidence base, and serves as an interim update for practitioners looking to fill the practical knowledge gap on this topic in conventional diabetes guidelines.
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Affiliation(s)
- Lina Shibib
- Department of Surgery and Cancer, Imperial College London, London, UK
| | - Mo Al-Qaisi
- Department of Surgery and Cancer, Imperial College London, London, UK
| | - Ahmed Ahmed
- Department of Surgery and Cancer, Imperial College London, London, UK
| | - Alexander D Miras
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - David Nott
- Department of Surgery and Cancer, Imperial College London, London, UK
| | - Marc Pelling
- Department of Surgery and Cancer, Imperial College London, London, UK
| | - Stephen E Greenwald
- Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary, University of London, London, UK
| | - Nicola Guess
- School of Life Sciences, Westminster University, London, UK
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Lipke K, Kubis-Kubiak A, Piwowar A. Molecular Mechanism of Lipotoxicity as an Interesting Aspect in the Development of Pathological States-Current View of Knowledge. Cells 2022; 11:cells11050844. [PMID: 35269467 PMCID: PMC8909283 DOI: 10.3390/cells11050844] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/22/2022] [Accepted: 02/25/2022] [Indexed: 02/06/2023] Open
Abstract
Free fatty acids (FFAs) play numerous vital roles in the organism, such as contribution to energy generation and reserve, serving as an essential component of the cell membrane, or as ligands for nuclear receptors. However, the disturbance in fatty acid homeostasis, such as inefficient metabolism or intensified release from the site of storage, may result in increased serum FFA levels and eventually result in ectopic fat deposition, which is unfavorable for the organism. The cells are adjusted for the accumulation of FFA to a limited extent and so prolonged exposure to elevated FFA levels results in deleterious effects referred to as lipotoxicity. Lipotoxicity contributes to the development of diseases such as insulin resistance, diabetes, cardiovascular diseases, metabolic syndrome, and inflammation. The nonobvious organs recognized as the main lipotoxic goal of action are the pancreas, liver, skeletal muscles, cardiac muscle, and kidneys. However, lipotoxic effects to a significant extent are not organ-specific but affect fundamental cellular processes occurring in most cells. Therefore, the wider perception of cellular lipotoxic mechanisms and their interrelation may be beneficial for a better understanding of various diseases’ pathogenesis and seeking new pharmacological treatment approaches.
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Abstract
The accumulation of an excessive amount of body fat can cause type 2 diabetes, and the risk of type 2 diabetes increases linearly with an increase in body mass index. Accordingly, the worldwide increase in the prevalence of obesity has led to a concomitant increase in the prevalence of type 2 diabetes. The cellular and physiological mechanisms responsible for the link between obesity and type 2 diabetes are complex and involve adiposity-induced alterations in β cell function, adipose tissue biology, and multi-organ insulin resistance, which are often ameliorated and can even be normalized with adequate weight loss.
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Affiliation(s)
- Samuel Klein
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO 63110, USA; Sansum Diabetes Research Institute, Santa Barbara, CA 93105, USA.
| | - Amalia Gastaldelli
- Institute of Clinical Physiology, National Research Council-CNR, Pisa 56100, Italy
| | - Hannele Yki-Järvinen
- Minerva Foundation Institute for Medical Research, 00290 Helsinki, Finland; Department of Medicine, University of Helsinki, Helsinki University Hospital, 00290 Helsinki, Finland
| | - Philipp E Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA; Department of Cell Biology, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
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Mukherjee N, Lin L, Contreras CJ, Templin AT. β-Cell Death in Diabetes: Past Discoveries, Present Understanding, and Potential Future Advances. Metabolites 2021; 11:796. [PMID: 34822454 PMCID: PMC8620854 DOI: 10.3390/metabo11110796] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/15/2021] [Accepted: 11/18/2021] [Indexed: 12/19/2022] Open
Abstract
β-cell death is regarded as a major event driving loss of insulin secretion and hyperglycemia in both type 1 and type 2 diabetes mellitus. In this review, we explore past, present, and potential future advances in our understanding of the mechanisms that promote β-cell death in diabetes, with a focus on the primary literature. We first review discoveries of insulin insufficiency, β-cell loss, and β-cell death in human diabetes. We discuss findings in humans and mouse models of diabetes related to autoimmune-associated β-cell loss and the roles of autoreactive T cells, B cells, and the β cell itself in this process. We review discoveries of the molecular mechanisms that underlie β-cell death-inducing stimuli, including proinflammatory cytokines, islet amyloid formation, ER stress, oxidative stress, glucotoxicity, and lipotoxicity. Finally, we explore recent perspectives on β-cell death in diabetes, including: (1) the role of the β cell in its own demise, (2) methods and terminology for identifying diverse mechanisms of β-cell death, and (3) whether non-canonical forms of β-cell death, such as regulated necrosis, contribute to islet inflammation and β-cell loss in diabetes. We believe new perspectives on the mechanisms of β-cell death in diabetes will provide a better understanding of this pathological process and may lead to new therapeutic strategies to protect β cells in the setting of diabetes.
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Affiliation(s)
- Noyonika Mukherjee
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
- Lilly Diabetes Center of Excellence, Indiana Biosciences Research Institute, Indianapolis, IN 46202, USA; (L.L.); (C.J.C.)
| | - Li Lin
- Lilly Diabetes Center of Excellence, Indiana Biosciences Research Institute, Indianapolis, IN 46202, USA; (L.L.); (C.J.C.)
| | - Christopher J. Contreras
- Lilly Diabetes Center of Excellence, Indiana Biosciences Research Institute, Indianapolis, IN 46202, USA; (L.L.); (C.J.C.)
- Department of Medicine, Roudebush Veterans Affairs Medical Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Andrew T. Templin
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
- Lilly Diabetes Center of Excellence, Indiana Biosciences Research Institute, Indianapolis, IN 46202, USA; (L.L.); (C.J.C.)
- Department of Medicine, Roudebush Veterans Affairs Medical Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Center for Diabetes and Metabolic Diseases, School of Medicine, Indiana University, Indianapolis, IN 46202, USA
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Nakagata T, Tamura Y, Kaga H, Sato M, Yamasaki N, Someya Y, Kadowaki S, Sugimoto D, Satoh H, Kawamori R, Watada H. Ingestion of an exogenous ketone monoester improves the glycemic response during oral glucose tolerance test in individuals with impaired glucose tolerance: A cross-over randomized trial. J Diabetes Investig 2021; 12:756-762. [PMID: 33010116 PMCID: PMC8088997 DOI: 10.1111/jdi.13423] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 08/10/2020] [Accepted: 09/27/2020] [Indexed: 01/14/2023] Open
Abstract
AIMS/INTRODUCTION As a low-carbohydrate diet and the use of sodium-glucose transporter-2 inhibitors are both known to increase D-beta-hydroxybutyrate levels, the effect of these levels on glucose metabolism has attracted attention. We investigated the acute effects of ketone monoester (KM) ingestion on blood glucose levels during the 75-g oral glucose tolerance test (OGTT) in participants with impaired glucose tolerance. MATERIALS AND METHODS Nine Japanese adults aged 48-62 years (4 men, 5 women) with impaired glucose tolerance participated in this study. After participants fasted overnight, we carried out OGTT for 180 min with and without KM ingestion on two separate days in a randomized cross-over design. We compared the area under the curve (AUC) of D-beta-hydroxybutyrate, glucose, insulin, C-peptide, glucagon and free fatty acids during OGTT. RESULTS The AUC of D-beta-hydroxybutyrate during OGTT was significantly higher with KM than without KM (KM 5995.3 ± 1257.1 mmol/L·h; without KM 116.1 ± 33.9 mmol/L·h, P < 0.0001), and the AUC of glucose with KM was significantly lower than that without KM (KM 406.6 ± 70.6 mg/dL·h; without KM 483.2 ± 74.3 mg/dL·h, P < 0.0001). This improved glucose excursion was associated with enhanced AUC of insulin during the first half (0-90 min) of OGTT, even though the AUC of C-peptide during this period was unchanged. In contrast, the AUC of insulin, C-peptide, glucagon and free fatty acids during 180 min of OGTT were similar in both conditions. CONCLUSION The ingestion of KM decreased the AUC of glucose during 75-g OGTT in Japanese individuals with impaired glucose tolerance, and the mechanism might involve elevated levels of circulating early phase insulin.
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Affiliation(s)
- Takashi Nakagata
- Sportology CenterJuntendo University Graduate School of MedicineTokyoJapan
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
- Department of Physical Activity ResearchNational Institute of Health and NutritionNIBIOHNTokyoJapan
| | - Yoshifumi Tamura
- Sportology CenterJuntendo University Graduate School of MedicineTokyoJapan
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
| | - Hideyoshi Kaga
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
| | - Motonori Sato
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
| | - Nozomu Yamasaki
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
| | - Yuki Someya
- Sportology CenterJuntendo University Graduate School of MedicineTokyoJapan
| | - Satoshi Kadowaki
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
| | - Daisuke Sugimoto
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
| | - Hiroaki Satoh
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
| | - Ryuzo Kawamori
- Sportology CenterJuntendo University Graduate School of MedicineTokyoJapan
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
| | - Hirotaka Watada
- Sportology CenterJuntendo University Graduate School of MedicineTokyoJapan
- Department of Metabolism & EndocrinologyJuntendo University Graduate School of MedicineTokyoJapan
- Center for Therapeutic Innovations in DiabetesJuntendo University Graduate School of MedicineTokyoJapan
- Center for Molecular DiabetologyJuntendo University Graduate School of MedicineTokyoJapan
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Abstract
BACKGROUND Obesity has been proven to be a risk factor for type 2 diabetes mellitus (T2DM) through numerous pathogenetic mechanisms. Unexpectedly, some studies suggest that subjects with overweight/obesity and T2DM have better clinical outcome than their normal weight peers. This finding is described as "obesity paradox" and calls into question the importance of weight loss in this specific population. OBJECTIVE This article is a narrative overview on the obesity and type 2 diabetes mellitus, particularly regarding the obesity paradox in T2DM patients. METHODS We used as sources MEDLINE/PubMed, CINAHL, EMBASE, and Cochrane Library, from inception to March 2020; we chose 30 relevant papers regarding the association of obesity with clinical outcome and mortality of patients affected by T2DM. RESULTS Many studies report that in patients with T2DM, overweight and obesity are associated with a better prognosis than underweight or normal weight, suggesting the presence of an obesity paradox. However, these studies have numerous limitations due to their mainly retrospective nature and to numerous confounding factors, such as associated pathologies, antidiabetic treatments, smoking habit, lack of data about distribution of body fat or weight history. CONCLUSION Literature data regarding the phenomenon of obesity paradox in T2DM patients are controversial due to the several limitations of the studies; therefore in the management of patients with overweight/obesity and T2DM is recommended referring to the established guidelines, which indicate diet and physical activity as the cornerstone of the treatment. LEVEL OF EVIDENCE Level V: narrative review.
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Sellers AJ, Pallubinsky H, Rense P, Bijnens W, van de Weijer T, Moonen-Kornips E, Schrauwen P, van Marken Lichtenbelt WD. The effect of cold exposure with shivering on glucose tolerance in healthy men. J Appl Physiol (1985) 2021; 130:193-205. [DOI: 10.1152/japplphysiol.00642.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
This is the first study to examine the effect of cold-induced shivering on subsequent glucose tolerance determined under thermoneutral conditions. Plasma glucose and insulin concentrations increased during the oral glucose tolerance test post shivering. Additionally, insulin sensitivity indices suggest insulin resistance following cold exposure. These results provide evidence for an acute post-shivering response, whereby glucose metabolism has deteriorated, contrary to the results from earlier studies on cold acclimation.
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Affiliation(s)
- Adam Jake Sellers
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
| | - Hannah Pallubinsky
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
| | - Pascal Rense
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
| | - Wouter Bijnens
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
| | - Tineke van de Weijer
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
| | - Esther Moonen-Kornips
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
| | - Patrick Schrauwen
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
| | - Wouter D. van Marken Lichtenbelt
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
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Dahlby T, Simon C, Backe MB, Dahllöf MS, Holson E, Wagner BK, Böni-Schnetzler M, Marzec MT, Lundh M, Mandrup-Poulsen T. Enhancer of Zeste Homolog 2 (EZH2) Mediates Glucolipotoxicity-Induced Apoptosis in β-Cells. Int J Mol Sci 2020; 21:ijms21218016. [PMID: 33137873 PMCID: PMC7672588 DOI: 10.3390/ijms21218016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/20/2020] [Accepted: 10/26/2020] [Indexed: 01/04/2023] Open
Abstract
Selective inhibition of histone deacetylase 3 (HDAC3) prevents glucolipotoxicity-induced β-cell dysfunction and apoptosis by alleviation of proapoptotic endoplasmic reticulum (ER) stress-signaling, but the precise molecular mechanisms of alleviation are unexplored. By unbiased microarray analysis of the β-cell gene expression profile of insulin-producing cells exposed to glucolipotoxicity in the presence or absence of a selective HDAC3 inhibitor, we identified Enhancer of zeste homolog 2 (EZH2) as the sole target candidate. β-Cells were protected against glucolipotoxicity-induced ER stress and apoptosis by EZH2 attenuation. Small molecule inhibitors of EZH2 histone methyltransferase activity rescued human islets from glucolipotoxicity-induced apoptosis. Moreover, EZH2 knockdown cells were protected against glucolipotoxicity-induced downregulation of the protective non-canonical Nuclear factor of kappa light polypeptide gene enhancer in B-cells (NFκB) pathway. We conclude that EZH2 deficiency protects from glucolipotoxicity-induced ER stress, apoptosis and downregulation of the non-canonical NFκB pathway, but not from insulin secretory dysfunction. The mechanism likely involves transcriptional regulation via EZH2 functioning as a methyltransferase and/or as a methylation-dependent transcription factor.
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Affiliation(s)
- Tina Dahlby
- Department of Biomedical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; (T.D.); (M.B.B.); (M.S.D.); (M.T.M.); (M.L.)
| | - Christian Simon
- Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, DK-2200 Copenhagen, Denmark;
| | - Marie Balslev Backe
- Department of Biomedical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; (T.D.); (M.B.B.); (M.S.D.); (M.T.M.); (M.L.)
| | - Mattias Salling Dahllöf
- Department of Biomedical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; (T.D.); (M.B.B.); (M.S.D.); (M.T.M.); (M.L.)
| | - Edward Holson
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; (E.H.); (B.K.W.)
| | - Bridget K. Wagner
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; (E.H.); (B.K.W.)
| | - Marianne Böni-Schnetzler
- Department of Biomedicine, University Hospital and University of Basel, 4031 Basel, Switzerland;
| | - Michal Tomasz Marzec
- Department of Biomedical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; (T.D.); (M.B.B.); (M.S.D.); (M.T.M.); (M.L.)
| | - Morten Lundh
- Department of Biomedical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; (T.D.); (M.B.B.); (M.S.D.); (M.T.M.); (M.L.)
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; (E.H.); (B.K.W.)
| | - Thomas Mandrup-Poulsen
- Department of Biomedical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark; (T.D.); (M.B.B.); (M.S.D.); (M.T.M.); (M.L.)
- Correspondence: ; Tel.: +45-30-33-03-87
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Turcotte AF, Grenier-Larouche T, Lacombe J, Carreau AM, Carpentier AC, Mac-Way F, Tchernof A, Richard D, Biertho L, Lebel S, Marceau S, Ferron M, Gagnon C. Association between changes in bioactive osteocalcin and glucose homeostasis after biliopancreatic diversion. Endocrine 2020; 69:526-535. [PMID: 32419080 DOI: 10.1007/s12020-020-02340-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 05/04/2020] [Indexed: 12/30/2022]
Abstract
PURPOSE Bone may regulate glucose homeostasis via uncarboxylated bioactive osteocalcin (ucOCN). This study explored whether changes in ucOCN and bone remodeling are associated with change in glucose homeostasis after biliopancreatic diversion (BPD). METHODS In this secondary exploratory analysis of a 1-year prospective observational study, 16 participants (11 men/5 women; 69% with type 2 diabetes; mean BMI 49.4 kg/m2) were assessed before, 3 days, 3 months and 12 months after BPD. Changes in plasma ucOCN and bone markers (C-terminal telopeptide (CTX), total osteocalcin (OCN)) were correlated with changes in insulin resistance or sensitivity indices (HOMA-IR; adipose tissue insulin resistance index (ADIPO-IR) and insulin sensitivity index (SI) from the hyperinsulinemic-euglycemic clamp), insulin secretion rate (ISR) from the hyperglycemic clamp, and disposition index (DI: SI × ISR) using Spearman correlations before and after adjustment for weight loss. RESULTS ucOCN was unchanged at 3 days but increased dramatically at 3 months (+257%) and 12 months (+498%). Change in ucOCN correlated significantly with change in CTX at 3 months (r = 0.62, p = 0.015) and 12 months (r = 0.64, p = 0.025) before adjustment for weight loss. It also correlated significantly with change in fasting insulin (r = -0.53, p = 0.035), HOMA-IR (r = -0.54, p = 0.033) and SI (r = 0.52, p = 0.041) at 3 days, and ADIPO-IR (r = -0.69, p = 0.003) and HbA1c (r = -0.69, p = 0.005) at 3 months. Change in OCN did not correlate with any glucose homeostasis indices. Results were similar after adjustment for weight loss. CONCLUSION The increase in ucOCN may be associated with the improvement in insulin resistance after BPD, independently of weight loss. These findings need to be confirmed in larger, less heterogeneous populations.
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Affiliation(s)
- Anne-Frédérique Turcotte
- Endocrinology and Nephrology Unit, CHU de Québec-Université Laval Research Centre, Québec City, QC, Canada
- Department of Medicine, Laval University, Québec City, QC, Canada
| | - Thomas Grenier-Larouche
- Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC, Canada
- Department of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Julie Lacombe
- Institut de recherches cliniques de Montréal, Montreal, QC, Canada
| | - Anne-Marie Carreau
- Endocrinology and Nephrology Unit, CHU de Québec-Université Laval Research Centre, Québec City, QC, Canada
- Department of Medicine, Laval University, Québec City, QC, Canada
| | - André C Carpentier
- Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC, Canada
- Department of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Fabrice Mac-Way
- Endocrinology and Nephrology Unit, CHU de Québec-Université Laval Research Centre, Québec City, QC, Canada
- Department of Medicine, Laval University, Québec City, QC, Canada
| | - André Tchernof
- Endocrinology and Nephrology Unit, CHU de Québec-Université Laval Research Centre, Québec City, QC, Canada
- Department of Medicine, Laval University, Québec City, QC, Canada
- Québec Heart and Lung Institute Research Centre, Québec City, QC, Canada
| | - Denis Richard
- Department of Medicine, Laval University, Québec City, QC, Canada
- Québec Heart and Lung Institute Research Centre, Québec City, QC, Canada
| | - Laurent Biertho
- Québec Heart and Lung Institute Research Centre, Québec City, QC, Canada
- Department of Surgery, Laval University, Québec City, QC, Canada
| | - Stefane Lebel
- Québec Heart and Lung Institute Research Centre, Québec City, QC, Canada
- Department of Surgery, Laval University, Québec City, QC, Canada
| | - Simon Marceau
- Québec Heart and Lung Institute Research Centre, Québec City, QC, Canada
- Department of Surgery, Laval University, Québec City, QC, Canada
| | - Mathieu Ferron
- Institut de recherches cliniques de Montréal, Montreal, QC, Canada
- Department of Medicine, Université de Montréal, Montreal, QC, Canada
| | - Claudia Gagnon
- Endocrinology and Nephrology Unit, CHU de Québec-Université Laval Research Centre, Québec City, QC, Canada.
- Department of Medicine, Laval University, Québec City, QC, Canada.
- Québec Heart and Lung Institute Research Centre, Québec City, QC, Canada.
- Institute of Nutrition and Functional Foods, Université Laval, Quebec City, QC, Canada.
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12
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Lacombe J, Al Rifai O, Loter L, Moran T, Turcotte AF, Grenier-Larouche T, Tchernof A, Biertho L, Carpentier AC, Prud'homme D, Rabasa-Lhoret R, Karsenty G, Gagnon C, Jiang W, Ferron M. Measurement of bioactive osteocalcin in humans using a novel immunoassay reveals association with glucose metabolism and β-cell function. Am J Physiol Endocrinol Metab 2020; 318:E381-E391. [PMID: 31935114 PMCID: PMC7395472 DOI: 10.1152/ajpendo.00321.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Osteocalcin (OCN) is a bone-derived hormone involved in the regulation of glucose metabolism. In serum, OCN exists in carboxylated and uncarboxylated forms (ucOCN), and studies in rodents suggest that ucOCN is the bioactive form of this hormone. Whether this is also the case in humans is unclear, because a reliable assay to measure ucOCN is not available. Here, we established and validated a new immunoassay (ELISA) measuring human ucOCN and used it to determine the level of bioactive OCN in two cohorts of overweight or obese subjects, with or without type 2 diabetes (T2D). The ELISA could specifically detect ucOCN concentrations ranging from 0.037 to 1.8 ng/mL. In a first cohort of overweight or obese postmenopausal women without diabetes (n = 132), ucOCN correlated negatively with fasting glucose (r = -0.18, P = 0.042) and insulin resistance assessed by the homeostatic model assessment of insulin resistance (r = -0.18, P = 0.038) and positively with insulin sensitivity assessed by a hyperinsulinemic-euglycemic clamp (r = 0.18, P = 0.043) or insulin sensitivity index derived from an oral glucose tolerance test (r = 0.26, P = 0.003). In a second cohort of subjects with severe obesity (n = 16), ucOCN was found to be lower in subjects with T2D compared with those without T2D (2.76 ± 0.38 versus 4.52 ± 0.06 ng/mL, P = 0.009) and to negatively correlate with fasting glucose (r = -0.50, P = 0.046) and glycated hemoglobin (r = -0.57, P = 0.021). Moreover, the subjects with ucOCN levels below 3 ng/mL had a reduced insulin secretion rate during a hyperglycemic clamp (P = 0.03). In conclusion, ucOCN measured with this novel and specific assay is inversely associated with insulin resistance and β-cell dysfunction in humans.
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Affiliation(s)
- Julie Lacombe
- Unité de Recherche en Physiologie Moléculaire, Institut de Recherches Cliniques de Montréal, Montréal, Québec, Canada
| | - Omar Al Rifai
- Unité de Recherche en Physiologie Moléculaire, Institut de Recherches Cliniques de Montréal, Montréal, Québec, Canada
- Department of Medicine, Université de Montréal, Québec, Canada
| | | | - Thomas Moran
- Center for Therapeutic Antibody Development, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Anne-Frédérique Turcotte
- Endocrinology and Nephrology Unit, CHU de Québec-Université Laval Research Center, Québec City, Québec, Canada
| | - Thomas Grenier-Larouche
- Québec Heart and Lung Institute Research Centre, Québec City, Québec, Canada
- Service d'Endocrinologie, Département de Médecine, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - André Tchernof
- Québec Heart and Lung Institute Research Centre, Québec City, Québec, Canada
| | - Laurent Biertho
- Québec Heart and Lung Institute Research Centre, Québec City, Québec, Canada
| | - André C Carpentier
- Service d'Endocrinologie, Département de Médecine, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Denis Prud'homme
- School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
- Institut du Savoir Montfort, Ottawa, Ontario, Canada
| | - Rémi Rabasa-Lhoret
- Département de Nutrition, Université de Montréal, Montréal, Québec, Canada
- Unité de Recherche en Maladies Métaboliques, Institut de Recherches Cliniques de Montréal, Montréal, Québec, Canada
| | - Gerard Karsenty
- Department of Genetics and Development, Columbia University Medical Center, New York, New York
| | - Claudia Gagnon
- Endocrinology and Nephrology Unit, CHU de Québec-Université Laval Research Center, Québec City, Québec, Canada
- Québec Heart and Lung Institute Research Centre, Québec City, Québec, Canada
- Department of Medicine, Université Laval, Québec City, Québec, Canada
| | | | - Mathieu Ferron
- Unité de Recherche en Physiologie Moléculaire, Institut de Recherches Cliniques de Montréal, Montréal, Québec, Canada
- Department of Medicine, Université de Montréal, Québec, Canada
- Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec, Canada
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13
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Weir GC. Glucolipotoxicity, β-Cells, and Diabetes: The Emperor Has No Clothes. Diabetes 2020; 69:273-278. [PMID: 31519699 PMCID: PMC7034184 DOI: 10.2337/db19-0138] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 04/08/2019] [Indexed: 12/21/2022]
Abstract
Reduction of β-cell mass and function is central to the pathogenesis of type 2 diabetes. The terms glucotoxicity, lipotoxicity, and glucolipotoxicity are used to describe potentially responsible processes. The premise is that chronically elevated glucose levels are toxic to β-cells, that elevated lipid levels in the form of circulating free fatty acids (FFA) also have toxic effects, and that the combination of the two, glucolipotoxicity, is particularly harmful. Much work has shown that high concentrations of FFA can be very damaging to β-cells when used for in vitro experiments, and when infused in large amounts in humans and rodents they produce suppression of insulin secretion. The purpose of this Perspective is to raise doubts about whether the FFA levels found in real-life situations are ever high enough to cause problems. Evidence supporting the importance of glucotoxicity is strong because there is such a tight correlation between defective insulin secretion and rising glucose levels. However, there is virtually no convincing evidence that the alterations in FFA levels occurring during progression to diabetes are pathogenic. Thus, the terms lipotoxicity and glucolipotoxicity should be used with great caution, if at all, because evidence supporting their importance has not yet emerged.
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Affiliation(s)
- Gordon C Weir
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA
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14
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Lytrivi M, Castell AL, Poitout V, Cnop M. Recent Insights Into Mechanisms of β-Cell Lipo- and Glucolipotoxicity in Type 2 Diabetes. J Mol Biol 2019; 432:1514-1534. [PMID: 31628942 DOI: 10.1016/j.jmb.2019.09.016] [Citation(s) in RCA: 192] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 09/15/2019] [Accepted: 09/16/2019] [Indexed: 12/24/2022]
Abstract
The deleterious effects of chronically elevated free fatty acid (FFA) levels on glucose homeostasis are referred to as lipotoxicity, and the concurrent exposure to high glucose may cause synergistic glucolipotoxicity. Lipo- and glucolipotoxicity have been studied for over 25 years. Here, we review the current evidence supporting the role of pancreatic β-cell lipo- and glucolipotoxicity in type 2 diabetes (T2D), including lipid-based interventions in humans, prospective epidemiological studies, and human genetic findings. In addition to total FFA quantity, the quality of FFAs (saturation and chain length) is a key determinant of lipotoxicity. We discuss in vitro and in vivo experimental models to investigate lipo- and glucolipotoxicity in β-cells and describe experimental pitfalls. Lipo- and glucolipotoxicity adversely affect many steps of the insulin production and secretion process. The molecular mechanisms underpinning lipo- and glucolipotoxic β-cell dysfunction and death comprise endoplasmic reticulum stress, oxidative stress and mitochondrial dysfunction, impaired autophagy, and inflammation. Crosstalk between these stress pathways exists at multiple levels and may aggravate β-cell lipo- and glucolipotoxicity. Lipo- and glucolipotoxicity are therapeutic targets as several drugs impact the underlying stress responses in β-cells, potentially contributing to their glucose-lowering effects in T2D.
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Affiliation(s)
- Maria Lytrivi
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels, Belgium; Division of Endocrinology, Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Anne-Laure Castell
- CRCHUM, Montréal, QC, Canada; Department of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Vincent Poitout
- CRCHUM, Montréal, QC, Canada; Department of Medicine, Université de Montréal, Montréal, QC, Canada.
| | - Miriam Cnop
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels, Belgium; Division of Endocrinology, Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium.
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15
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Takeuchi M, Minato S, Kitaoka K, Tsuboi A, Kurata M, Kazumi T, Fukuo K. Higher Fasting and Postprandial Free Fatty Acid Levels Are Associated With Higher Muscle Insulin Resistance and Lower Insulin Secretion in Young Non-Obese Women. J Clin Med Res 2018; 10:822-829. [PMID: 30344817 PMCID: PMC6188023 DOI: 10.14740/jocmr3534w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Accepted: 08/20/2018] [Indexed: 12/02/2022] Open
Abstract
Background To assess the relationship of the shape of glucose concentration curve during a standardized meal test to serum free fatty acid (FFA) concentrations, insulin resistance and insulin secretion in young non-obese women. Methods Thirty-five young women had a standardized meal for breakfast with measurement of glucose, insulin and FFA concentrations at 0 (fasting), 30, 60 and 120 min; the areas under the concentration curves were calculated (AUCg, AUCi and AUCffa, respectively). Meal-induced insulin response (MIR) was calculated as the ratio between the incremental insulin and glucose concentrations during the first 30 min of meal tests. In two women (group A), post-breakfast glucose (PBG) returned to levels below fasting plasma glucose (FPG) at 30 min; in 15 and 11 women, PBG returned to levels below FPG at 60 and 120 min (groups B and C, respectively). In the remaining seven women (group D), PBG never fell below FPG. Results Despite no difference in fasting insulin and AUCi, fasting FFA, AUCg and AUCffa were the lowest in group A, increased linearly from group B to C and plateaued in group D, whereas MIR might be the highest in group A, decreased from group B to C and plateaued in group D. Conclusion Young women whose PBG returned to FPG more slowly had higher muscle insulin resistance and lower MIR associated with higher fasting and postprandial FFA levels compared with young women whose PBG returned to baseline more quickly.
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Affiliation(s)
- Mika Takeuchi
- Department of Food Sciences and Nutrition, School of Human Environmental Sciences, Mukogawa Women's University, Nishinomiya, Hyogo, Japan
| | - Satomi Minato
- Research Institute for Nutrition Sciences, Mukogawa Women's University, Nishinomiya, Hyogo, Japan.,Graduate School of Human Science and Environment, University of Hyogo, Himeji, Hyogo, Japan
| | - Kaori Kitaoka
- Research Institute for Nutrition Sciences, Mukogawa Women's University, Nishinomiya, Hyogo, Japan.,Department of Welfare and Nutrition, Faculty of Health Welfare, Kansai University of Welfare Sciences, Kashiwara, Osaka, Japan
| | - Ayaka Tsuboi
- Research Institute for Nutrition Sciences, Mukogawa Women's University, Nishinomiya, Hyogo, Japan.,Department of Nutrition, Osaka City Juso Hospital, Osaka, Japan
| | - Miki Kurata
- Department of Food Sciences and Nutrition, School of Human Environmental Sciences, Mukogawa Women's University, Nishinomiya, Hyogo, Japan.,Research Institute for Nutrition Sciences, Mukogawa Women's University, Nishinomiya, Hyogo, Japan
| | - Tsutomu Kazumi
- Research Institute for Nutrition Sciences, Mukogawa Women's University, Nishinomiya, Hyogo, Japan.,Diabetes Division, Kohnan Kakogawa Hospital, Kakogawa, Hyogo, Japan
| | - Keisuke Fukuo
- Department of Food Sciences and Nutrition, School of Human Environmental Sciences, Mukogawa Women's University, Nishinomiya, Hyogo, Japan.,Research Institute for Nutrition Sciences, Mukogawa Women's University, Nishinomiya, Hyogo, Japan
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16
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Bissonnette S, Saint-Pierre N, Lamantia V, Leroux C, Provost V, Cyr Y, Rabasa-Lhoret R, Faraj M. High plasma apolipoprotein B identifies obese subjects who best ameliorate white adipose tissue dysfunction and glucose-induced hyperinsulinemia after a hypocaloric diet. Am J Clin Nutr 2018; 108:62-76. [PMID: 29917037 DOI: 10.1093/ajcn/nqy070] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 03/21/2018] [Indexed: 11/14/2022] Open
Abstract
Background To optimize the prevention of type 2 diabetes (T2D), high-risk obese subjects with the best metabolic recovery after a hypocaloric diet should be targeted. Apolipoprotein B lipoproteins (apoB lipoproteins) induce white adipose tissue (WAT) dysfunction, which in turn promotes postprandial hypertriglyceridemia, insulin resistance (IR), and hyperinsulinemia. Objective The aim of this study was to explore whether high plasma apoB, or number of plasma apoB lipoproteins, identifies subjects who best ameliorate WAT dysfunction and related risk factors after a hypocaloric diet. Design Fifty-nine men and postmenopausal women [mean ± SD age: 58 ± 6 y; body mass index (kg/m2): 32.6 ± 4.6] completed a prospective study with a 6-mo hypocaloric diet (-500 kcal/d). Glucose-induced insulin secretion (GIIS) and insulin sensitivity (IS) were measured by 1-h intravenous glucose-tolerance test (IVGTT) followed by a 3-h hyperinsulinemic-euglycemic clamp, respectively. Ex vivo gynoid WAT function (i.e., hydrolysis and storage of 3H-triolein-labeled triglyceride-rich lipoproteins) and 6-h postprandial plasma clearance of a 13C-triolein-labeled high-fat meal were measured in a subsample (n = 25). Results Postintervention first-phase GIISIVGTT and total C-peptide secretion decreased in both sexes, whereas second-phase and total GIISIVGTT and clamp IS were ameliorated in men (P < 0.05). Baseline plasma apoB was associated with a postintervention increase in WAT function (r = 0.61) and IS (glucose infusion rate divided by steady state insulin (M/Iclamp) r = 0.30) and a decrease in first-phase, second-phase, and total GIISIVGTT (r = -0.30 to -0.35) without sex differences. The association with postintervention amelioration in WAT function and GIISIVGTT was independent of plasma cholesterol (total, LDL, and HDL), sex, and changes in body composition. Subjects with high baseline plasma apoB (1.2 ± 0.2 g/L) showed a significant increase in WAT function (+105%; P = 0.012) and a decrease in total GIISIVGTT (-34%; P ≤ 0.001), whereas sex-matched subjects with low plasma apoB (0.7 ± 0.1 g/L) did not, despite equivalent changes in body composition and energy intake and expenditure. Conclusions High plasma apoB identifies obese subjects who best ameliorate WAT dysfunction and glucose-induced hyperinsulinemia, independent of changes in adiposity after consumption of a hypocaloric diet. We propose that subjects with high plasma apoB represent an optimal target group for the primary prevention of T2D by hypocaloric diets. This trial was registered at BioMed Central as ISRCTN14476404.
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Affiliation(s)
- Simon Bissonnette
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada.,Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada.,Montreal Diabetes Research Center, Montreal (MDRC), Quebec, Canada
| | | | - Valerie Lamantia
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada.,Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada.,Montreal Diabetes Research Center, Montreal (MDRC), Quebec, Canada
| | - Catherine Leroux
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada
| | - Viviane Provost
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada.,Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada.,Montreal Diabetes Research Center, Montreal (MDRC), Quebec, Canada
| | - Yannick Cyr
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada.,Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada.,Montreal Diabetes Research Center, Montreal (MDRC), Quebec, Canada
| | - Remi Rabasa-Lhoret
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada.,Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada.,Montreal Diabetes Research Center, Montreal (MDRC), Quebec, Canada
| | - May Faraj
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada.,Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada.,Montreal Diabetes Research Center, Montreal (MDRC), Quebec, Canada
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17
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Connolly A, Leblanc S, Baillargeon JP. Role of Lipotoxicity and Contribution of the Renin-Angiotensin System in the Development of Polycystic Ovary Syndrome. Int J Endocrinol 2018; 2018:4315413. [PMID: 29971102 PMCID: PMC6008888 DOI: 10.1155/2018/4315413] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Accepted: 05/03/2018] [Indexed: 12/15/2022] Open
Abstract
Polycystic ovary syndrome (PCOS) is a common and significant condition associated with hyperandrogenism, infertility, low quality of life, and metabolic comorbidities. One possible explanation of PCOS development is cellular dysfunction induced by nonesterified fatty acids (NEFAs), that is, lipotoxicity, which could explain both the hyperandrogenemia and insulin resistance that characterize women with PCOS. The literature suggests that androgen biosynthesis may be induced by overexposure of androgen-secreting tissues to NEFA and/or defective NEFA metabolism, leading to lipotoxic effects. Indeed, lipotoxicity could trigger androgenic hyperresponsiveness to insulin, LH, and ACTH. In most PCOS women, lipotoxicity also causes insulin resistance, inducing compensatory hyperinsulinemia, and may thus further increase hyperandrogenemia. Many approaches aimed at insulin sensitization also reduce lipotoxicity and have been shown to treat PCOS hyperandrogenemia. Furthermore, our group and others found that angiotensin II type 2 receptor (AT2R) activation is able to improve lipotoxicity. We provided evidence, using C21/M24, that AT2R activation improves adipocytes' size and insulin sensitivity in an insulin-resistant rat model, as well as androgen levels in a PCOS obese rat model. Taken together, these findings point toward the important role of lipotoxicity in PCOS development and of the RAS system as a new target for the treatment of PCOS.
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Affiliation(s)
- Alexandre Connolly
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, 3001 12e Avenue Nord, Université de Sherbrooke, Sherbrooke, QC, Canada J1H 5N4
- Division of Endocrinology, Department of Medicine, Faculty of Medicine and Health Sciences, 3001 12e Avenue Nord, Université de Sherbrooke, Sherbrooke, QC, Canada J1H 5N4
| | - Samuel Leblanc
- Division of Endocrinology, Department of Medicine, Faculty of Medicine and Health Sciences, 3001 12e Avenue Nord, Université de Sherbrooke, Sherbrooke, QC, Canada J1H 5N4
| | - Jean-Patrice Baillargeon
- Division of Endocrinology, Department of Medicine, Faculty of Medicine and Health Sciences, 3001 12e Avenue Nord, Université de Sherbrooke, Sherbrooke, QC, Canada J1H 5N4
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18
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Previti E, Salinari S, Bertuzzi A, Capristo E, Bornstein S, Mingrone G. Glycemic control after metabolic surgery: a Granger causality and graph analysis. Am J Physiol Endocrinol Metab 2017; 313:E622-E630. [PMID: 28698280 DOI: 10.1152/ajpendo.00042.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 07/10/2017] [Accepted: 07/10/2017] [Indexed: 02/05/2023]
Abstract
The purpose of this study was to examine the contribution of nonesterified fatty acids (NEFA) and incretin to insulin resistance and diabetes amelioration after malabsorptive metabolic surgery that induces steatorrhea. In fact, NEFA infusion reduces glucose-stimulated insulin secretion, and high-fat diets predict diabetes development. Six healthy controls, 11 obese subjects, and 10 type 2 diabetic (T2D) subjects were studied before and 1 mo after biliopancreatic diversion (BPD). Twenty-four-hour plasma glucose, NEFA, insulin, C-peptide, glucagon-like peptide-1 (GLP-1), and gastric inhibitory polypeptide (GIP) time courses were obtained and analyzed by Granger causality and graph analyses. Insulin sensitivity and secretion were computed by the oral glucose minimal model. Before metabolic surgery, NEFA levels had the strongest influence on the other variables in both obese and T2D subjects. After surgery, GLP-1 and C-peptide levels controlled the system in obese and T2D subjects. Twenty-four-hour GIP levels were markedly reduced after BPD. Finally, not only did GLP-1 levels play a central role, but also insulin and C-peptide levels had a comparable relevance in the network of healthy controls. After BPD, insulin sensitivity was completely normalized in both obese and T2D individuals. Increased 24-h GLP-1 circulating levels positively influenced glucose homeostasis in both obese and T2D subjects who underwent a malabsorptive bariatric operation. In the latter, the reduction of plasma GIP levels also contributed to the improvement of glucose metabolism. It is possible that the combination of a pharmaceutical treatment reducing GIP and increasing GLP-1 plasma levels will contribute to better glycemic control in T2D. The application of Granger causality and graph analyses sheds new light on the pathophysiology of metabolic surgery.
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Affiliation(s)
- Elena Previti
- Department of Computer, Control, and Management Engineering "Antonio Ruberti," Sapienza University of Rome, Rome, Italy
| | - Serenella Salinari
- Department of Computer, Control, and Management Engineering "Antonio Ruberti," Sapienza University of Rome, Rome, Italy
| | - Alessandro Bertuzzi
- Institute for System Analysis and Computer Science "Antonio Ruberti," Consiglio Nazionale delle Ricerche, Rome, Italy
| | - Esmeralda Capristo
- Department of Internal Medicine, Catholic University of the Sacred Heart, Rome, Italy
| | - Stephan Bornstein
- Department of Medicine III, Universitätsklinikum Carl Gustav Carus Dresden, Technische Universität Dresden, Dresden, Germany; and
- Diabetes and Nutritional Sciences, King's College London, London, United Kingdom
| | - Geltrude Mingrone
- Department of Internal Medicine, Catholic University of the Sacred Heart, Rome, Italy;
- Diabetes and Nutritional Sciences, King's College London, London, United Kingdom
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19
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Doliba NM, Liu Q, Li C, Chen P, Liu C, Naji A, Matschinsky FM. Inhibition of cholinergic potentiation of insulin secretion from pancreatic islets by chronic elevation of glucose and fatty acids: Protection by casein kinase 2 inhibitor. Mol Metab 2017; 6:1240-1253. [PMID: 29031723 PMCID: PMC5641685 DOI: 10.1016/j.molmet.2017.07.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 07/24/2017] [Accepted: 07/31/2017] [Indexed: 01/24/2023] Open
Abstract
Objectives Chronic hyperlipidemia and hyperglycemia are characteristic features of type 2 diabetes (T2DM) that are thought to cause or contribute to β-cell dysfunction by “glucolipotoxicity.” Previously we have shown that acute treatment of pancreatic islets with fatty acids (FA) decreases acetylcholine-potentiated insulin secretion. This acetylcholine response is mediated by M3 muscarinic receptors, which play a key role in regulating β-cell function. Here we examine whether chronic FA exposure also inhibits acetylcholine-potentiated insulin secretion using mouse and human islets. Methods Islets were cultured for 3 or 4 days at different glucose concentration with 0.5 mM palmitic acid (PA) or a 2:1 mixture of PA and oleic acid (OA) at 1% albumin (PA/BSA molar ratio 3.3). Afterwards, the response to glucose and acetylcholine were studied in perifusion experiments. Results FA-induced impairment of insulin secretion and Ca2+ signaling depended strongly on the glucose concentrations of the culture medium. PA and OA in combination reduced acetylcholine potentiation of insulin secretion more than PA alone, both in mouse and human islets, with no evidence of a protective role of OA. In contrast, lipotoxicity was not observed with islets cultured for 3 days in medium containing less than 1 mM glucose and a mixture of glutamine and leucine (7 mM each). High glucose and FAs reduced endoplasmic reticulum (ER) Ca2+ storage capacity; however, preserving ER Ca2+ by blocking the IP3 receptor with xestospongin C did not protect islets from glucolipotoxic effects on insulin secretion. In contrast, an inhibitor of casein kinase 2 (CK2) protected the glucose dependent acetylcholine potentiation of insulin secretion in mouse and human islets against glucolipotoxicity. Conclusions These results show that chronic FA treatment decreases acetylcholine potentiation of insulin secretion and that this effect is strictly glucose dependent and might involve CK2 phosphorylation of β-cell M3 muscarinic receptors. Glucolipotoxicity impairs acetylcholine-potentiation of insulin secretion. Glucose amplification of insulin secretion rather than triggering is damaged by FA. Inhibitor of casein kinase 2 preserved islet function against glucolipotoxicity.
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Affiliation(s)
- Nicolai M Doliba
- Department of Biochemistry and Biophysics, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA; Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA.
| | - Qin Liu
- Department of Biochemistry and Biophysics, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA
| | - Changhong Li
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA; Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Pan Chen
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Chengyang Liu
- Department of Surgery, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA; Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA
| | - Ali Naji
- Department of Surgery, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA; Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA
| | - Franz M Matschinsky
- Department of Biochemistry and Biophysics, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA; Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA
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20
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Yang X, Sun L, Zhao A, Hu X, Qing Y, Jiang J, Yang C, Xu T, Wang P, Liu J, Zhang J, He L, Jia W, Wan C. Serum fatty acid patterns in patients with schizophrenia: a targeted metabonomics study. Transl Psychiatry 2017; 7:e1176. [PMID: 28742081 PMCID: PMC5538128 DOI: 10.1038/tp.2017.152] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 04/25/2017] [Accepted: 06/07/2017] [Indexed: 12/21/2022] Open
Abstract
Previous studies have indicated that schizophrenia is linked to abnormal lipid metabolism. Free fatty acids (FFAs) in peripheral blood can reflect the status of lipid metabolism in human body. The purpose of this study was to scan the FFA pattern and elucidate the characteristics of lipid metabolic abnormality in schizophrenia patients. One hundred and ten patients with schizophrenia (SCZs) and 109 healthy controls (HCs) were included in the study and divided into a discovery set and a validation set. Forty-seven serum FFAs were detected by UPLC-QTOF-MS and 39 of them were absolutely quantified by establishing standard curves. Monounsaturated fatty acids (MUFAs) and ω-6 polyunsaturated fatty acids (ω-6 PUFAs) were significantly increased in SCZs compared with HCs. Desaturation from saturated fatty acids to MUFAs and β-oxidation were enhanced, as estimated by the ratios of products to precursors. These results suggest that lipolysis and β-oxidation are upregulated in SCZ, presumably resulting from insufficient brain energy supply.
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Affiliation(s)
- X Yang
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Key Laboratory of Translational Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University, Shanghai, China
| | - L Sun
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Key Laboratory of Translational Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University, Shanghai, China
| | - A Zhao
- Center for Translational Medicine and Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - X Hu
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Key Laboratory of Translational Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University, Shanghai, China
| | - Y Qing
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Key Laboratory of Translational Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University, Shanghai, China
| | - J Jiang
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Key Laboratory of Translational Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University, Shanghai, China
| | - C Yang
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Key Laboratory of Translational Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University, Shanghai, China
| | - T Xu
- Discipline of Neuroscience, Department of Anatomy, Histology and Embryology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - P Wang
- The Fourth People’s Hospital of Wuhu, Wuhu, China
| | - J Liu
- Center for Translational Medicine and Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - J Zhang
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Key Laboratory of Translational Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University, Shanghai, China
| | - L He
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Key Laboratory of Translational Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University, Shanghai, China
| | - W Jia
- Center for Translational Medicine and Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China,Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China E-mail:
| | - C Wan
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Key Laboratory of Translational Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University, Shanghai, China,Collaborative Innovation Center of Genetics and Development, Shanghai, China,Bio-X Institutes, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030, China. E-mail:
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Abstract
Purpose Hepatocyte nuclear factor 1 alpha (HNF1α) defects cause Mature Onset Diabetes of the Young type 3 (MODY3), characterized by defects in beta-cell insulin secretion. However, HNF1α is involved in many other metabolic pathways with relevance for monogenic or polygenic type 2 diabetes. We aimed to investigate gut hormones, lipids, and insulin regulation in response to a meal test in HNF1α defect carriers (MODY3) compared to non-diabetic subjects (controls) and type 2 diabetes (T2D). Methods We administered a standardized liquid meal to each participant. Over 6 hours, we measured post-meal responses of insulin regulation (blood glucose, c-peptide, insulin), gut hormones (ghrelin, glucose-dependent insulinotropic polypeptide, glucagon-like peptide-1) and lipids (non-esterified fatty acids [NEFA] and triglycerides). Results We found that MODY3 participants had lower insulin secretion indices than controls and T2D participants, showing the expected β-cell defect. MODY3 had similar glycated hemoglobin levels (HbA1c median [IQR]: 6.5 [5.6–7.6]%) compared to T2D (median: 6.6 [6.2–6.9]%; P<0.05). MODY3 had greater insulin sensitivity (Matsuda index: 71.9 [29.6; 125.5]) than T2D (3.2 [4.0; 6.0]; P<0.05). MODY3 experienced a larger decrease in the ratio of NEFA to insulin (NEFA 30–0 / insulin 30–0: -39 [-78; -30] x104) in the early post-prandial period (0–30 minutes) compared to controls and to T2D (-2.0 [-0.6; -6.4] x104; P<0.05). MODY3 had lower fasting (0.66 [0.46; 1.2] mM) and post-meal triglycerides levels compared to T2D (fasting: 2.3 [1.7; 2.7] mM; P<0.05). We did not detect significant post-meal differences in ghrelin and incretins between MODY3 and other groups. Conclusion In response to a standard meal test, MODY3 showed greater early post-prandial NEFA diminution in response to relatively low early insulin secretion, and they maintained very low post-prandial triglycerides levels.
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Owei I, Umekwe N, Wan J, Dagogo-Jack S. Plasma lipid levels predict dysglycemia in a biracial cohort of nondiabetic subjects: Potential mechanisms. Exp Biol Med (Maywood) 2016; 241:1961-1967. [PMID: 27430991 PMCID: PMC5068467 DOI: 10.1177/1535370216659946] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Accepted: 06/27/2016] [Indexed: 01/04/2023] Open
Abstract
Dyslipidemia and dysglycemia are etiologically associated, but the direction, chronology, and mechanisms of the association are not fully understood. We, therefore, analyzed data from 335 healthy adults (184 black, 151 white) enrolled in the Pathobiology of Prediabetes in A Biracial Cohort study. Subjects underwent oral glucose tolerance test (OGTT) and were enrolled if they had normal fasting and 2-h plasma glucose levels. Assessments during year 1 included anthropometry, fasting lipid profile, insulin sensitivity, and insulin secretion. Thereafter, OGTT was assessed annually for 5.5 years. The primary outcome was occurrence of prediabetes (impaired fasting glucose or impaired glucose tolerance) or diabetes. During a mean follow-up of 2.62 years, 110 participants (32.8%) developed prediabetes (N = 100) or diabetes (N = 10). In multivariate logistic regression models, higher baseline low-density lipoprotein (LDL) cholesterol and triglyceride levels and lower HDL cholesterol levels significantly increased the risk of incident prediabetes. The combined relative risk (95% confidence interval [CI]) of prediabetes for participants with lower baseline HDL cholesterol (10th vs. 90th percentile), higher LDL cholesterol (90th vs. 10th percentile) and high triglycerides levels (90th vs. 10th percentile) was 4.12 (95% CI 1.61-10.56), P = 0.0032. At baseline, lipid values showed significant associations with measures of adiposity, glycemia, insulin sensitivity, and secretion. In both ethnic groups, waist circumference correlated positively with triglycerides and inversely with HDL cholesterol levels (P = 0.0004-<0.0001); fasting plasma glucose correlated positively with triglycerides and LDL cholesterol levels and inversely with HDL cholesterol levels (P = 0.006-<0.0001); insulin sensitivity correlated positively with HDL cholesterol and inversely with triglyceride levels (P < 0.0001), and insulin secretion correlated positively with triglycerides (P = 0.01) and inversely with HDL cholesterol (P < 0.0001). We conclude that a baseline lipidemic signature identifies normoglycemic individuals at high risk for future glycemic progression, via congruent associations with adiposity and glucoregulatory mechanisms. These findings suggest that early lifestyle intervention could ameliorate progressive dyslipidemia and dysglycemia.
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Affiliation(s)
- Ibiye Owei
- Division of Endocrinology, Diabetes and Metabolism, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Nkiru Umekwe
- Division of Endocrinology, Diabetes and Metabolism, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Jim Wan
- Department of Preventive Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Samuel Dagogo-Jack
- Division of Endocrinology, Diabetes and Metabolism, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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23
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Rebelos E, Seghieri M, Natali A, Balkau B, Golay A, Piatti PM, Lalic NM, Laakso M, Mari A, Ferrannini E. Influence of endogenous NEFA on beta cell function in humans. Diabetologia 2015; 58:2344-51. [PMID: 26160433 DOI: 10.1007/s00125-015-3685-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 06/15/2015] [Indexed: 12/20/2022]
Abstract
AIMS/HYPOTHESIS It is a commonly held view that chronically elevated NEFA levels adversely affect insulin secretion and insulin action (lipotoxicity). However, the effect of NEFA on beta cell function has only been explored using acute NEFA elevations. Our aim was to analyse the relationship between endogenous NEFA levels and beta cell function. METHODS In 1,267 individuals followed-up for 3 years, we measured insulin sensitivity (by clamp) and beta cell function (by C-peptide modelling during OGTT and as the acute insulin response [AIR] to IVGTT). RESULTS At baseline, both fasting and insulin-suppressed NEFA levels were higher across glucose tolerance groups, while insulin sensitivity was lower, insulin output was higher, and beta cell glucose sensitivity and AIR were lower (all p < 0.0001). In multiple logistic analyses adjusting for age, BMI, WHR and glucose tolerance, both fasting and insulin-suppressed NEFA levels were inversely related to insulin sensitivity, as expected (both p < 0.0001). Furthermore, after adjusting for insulin sensitivity, insulin-suppressed NEFA were positively associated with total insulin output (p = 0.0042). In contrast, neither fasting nor insulin-suppressed NEFA were related to beta cell glucose sensitivity or AIR. At follow-up, worsening of glucose tolerance (n = 126) was predicted by lower insulin and beta cell glucose sensitivity. In this model, baseline NEFA were not significant predictors of progression. CONCLUSIONS/INTERPRETATION In the non-diabetic state and in subjects with impaired glucose tolerance, circulating endogenous NEFA are not independently associated measures of beta cell function, and do not predict deterioration of glucose tolerance. Thus, in the Relationship Between Insulin Sensitivity and Cardiovascular Disease (RISC) cohort there is no evidence for beta cell lipotoxicity of endogenous total NEFA concentrations.
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Affiliation(s)
- Eleni Rebelos
- Department of Clinical & Experimental Medicine, University of Pisa, Via Roma, 67, 56126, Pisa, Italy
| | - Marta Seghieri
- Department of Clinical & Experimental Medicine, University of Pisa, Via Roma, 67, 56126, Pisa, Italy
| | - Andrea Natali
- Department of Clinical & Experimental Medicine, University of Pisa, Via Roma, 67, 56126, Pisa, Italy
| | | | - Alain Golay
- Division of Therapeutical Teaching for Chronic Diseases, University Hospital, Geneva, Switzerland
| | - Pier Marco Piatti
- Cardio-Metabolism and Clinical Trials Unit, Department of Internal Medicine, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Nebojsa M Lalic
- Clinic for Endocrinology, Diabetes and Metabolic Diseases, CCS, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Markku Laakso
- Department of Medicine, University of Eastern Finland and Kuopio University Hospital, Kuopio, Finland
| | - Andrea Mari
- CNR Institute of Neuroscience, Padova, Italy
| | - Ele Ferrannini
- Department of Clinical & Experimental Medicine, University of Pisa, Via Roma, 67, 56126, Pisa, Italy.
- CNR Institute of Clinical Physiology, Pisa, Italy.
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Torres-Rasgado E, Porchia LM, Ruiz-Vivanco G, Gonzalez-Mejia ME, Báez-Duarte BG, Pulido-Pérez P, Rivera A, Romero JR, Pérez-Fuentes R. Obese first-degree relatives of patients with type 2 diabetes with elevated triglyceride levels exhibit increased β-cell function. Metab Syndr Relat Disord 2014; 13:45-51. [PMID: 25423015 DOI: 10.1089/met.2014.0095] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Type 2 diabetes mellitus (T2DM) is characterized as a disease continuum that is marked by metabolic changes that are present for several years, sometimes well before frank diagnosis of T2DM. Genetic predisposition, ethnicity, geography, alterations in BMI, and lipid profile are considered important markers for the pathogenesis of T2DM through mechanisms that remain unresolved and controversial. The aim of this study was to investigate the relationship between triglycerides (TGs) and β-cell function, insulin resistance (IR), and insulin sensitivity (IS) in obese first-degree relatives of patients with T2DM (FDR-T2DM) among subjects from central Mexico with normal glucose tolerance (NGT). METHODS We studied 372 FDR-T2DM subjects (ages,18-65) and determined body mass index (BMI), fasting plasma glucose (FPG), oral glucose tolerance test (OGTT), insulin, and TGs levels. Subjects were categorized based on glycemic control [NGT, prediabetes (PT2DM), or T2DM]. NGT subjects were further categorized by BMI [normal weight (Ob-) or obese (Ob+)] and TGs levels (TG-, <150 mg/dL, or TG+, ≥150 mg/dL). β-cell function, IR, and IS were determined by the homeostasis model assessment of β-cell function (HOMA2-β), homeostasis model assessment of insulin resistance (HOMA2-IR), and Quantitative Insulin Sensitivity Check Index (QUICKI) indices, respectively. RESULTS The obese subjects with elevated TGs levels had 21%-60% increased β-cell function when compared to all groups (P<0.05). In addition, this group had insulin levels, IS, and IR similar to PT2DM. Furthermore, only in obese subjects did TGs correlate with β-cell function (ρ=0.502, P<0.001). CONCLUSION We characterized FDR-T2DM subjects from central Mexico with NGT and revealed a class of obese subjects with elevated TGs and β-cell function, which may precede PT2DM.
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Affiliation(s)
- Enrique Torres-Rasgado
- 1 Facultad de Medicina, Benemérita Universidad Autónoma de Puebla , Puebla, Puebla, México
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25
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Hatanaka M, Maier B, Sims EK, Templin AT, Kulkarni RN, Evans-Molina C, Mirmira RG. Palmitate induces mRNA translation and increases ER protein load in islet β-cells via activation of the mammalian target of rapamycin pathway. Diabetes 2014; 63:3404-15. [PMID: 24834975 PMCID: PMC4171659 DOI: 10.2337/db14-0105] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Saturated free fatty acids (FFAs) have complex effects on the islet β-cell, acutely promoting adaptive hyperplasia but chronically impairing insulin release. The acute effects of FFAs remain incompletely defined. To elucidate these early molecular events, we incubated mouse β-cells and islets with palmitate and then studied mRNA translation by polyribosomal profiling and analyzed signaling pathways by immunoblot analysis. We found that palmitate acutely increases polyribosome occupancy of total RNA, consistent with an increase in mRNA translation. This effect on translation was attributable to activation of mammalian target of rapamycin (mTOR) pathways via L-type Ca(2+) channels but was independent of insulin signaling. Longer incubations led to depletion of polyribosome-associated RNA, consistent with activation of the unfolded protein response (UPR). Pharmacologic inhibition of mTOR suppressed both the acute effects of palmitate on mRNA translation and the chronic effects on the UPR. Islets from mice fed a high-fat diet for 7 days showed increases in polyribosome-associated RNA and phosphorylation of S6K, both consistent with activation of mTOR. Our results suggest that palmitate acutely activates mRNA translation and that this increase in protein load contributes to the later UPR.
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Affiliation(s)
- Masayuki Hatanaka
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN
| | - Bernhard Maier
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN
| | - Emily K Sims
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN
| | - Andrew T Templin
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN
| | - Rohit N Kulkarni
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, MA
| | - Carmella Evans-Molina
- Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN Department of Medicine, Indiana University School of Medicine, Indianapolis, IN Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN
| | - Raghavendra G Mirmira
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN Department of Medicine, Indiana University School of Medicine, Indianapolis, IN Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN
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26
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Hall E, Volkov P, Dayeh T, Bacos K, Rönn T, Nitert MD, Ling C. Effects of palmitate on genome-wide mRNA expression and DNA methylation patterns in human pancreatic islets. BMC Med 2014; 12:103. [PMID: 24953961 PMCID: PMC4065864 DOI: 10.1186/1741-7015-12-103] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 04/25/2014] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Circulating free fatty acids are often elevated in patients with type 2 diabetes (T2D) and obese individuals. Chronic exposure to high levels of saturated fatty acids has detrimental effects on islet function and insulin secretion. Altered gene expression and epigenetics may contribute to T2D and obesity. However, there is limited information on whether fatty acids alter the genome-wide transcriptome profile in conjunction with DNA methylation patterns in human pancreatic islets. To dissect the molecular mechanisms linking lipotoxicity to impaired insulin secretion, we investigated the effects of a 48 h palmitate treatment in vitro on genome-wide mRNA expression and DNA methylation patterns in human pancreatic islets. METHODS Genome-wide mRNA expression was analyzed using Affymetrix GeneChip(®) Human Gene 1.0 ST whole transcript-based array (n = 13) and genome-wide DNA methylation was analyzed using Infinium HumanMethylation450K BeadChip (n = 13) in human pancreatic islets exposed to palmitate or control media for 48 h. A non-parametric paired Wilcoxon statistical test was used to analyze mRNA expression. Apoptosis was measured using Apo-ONE(®) Homogeneous Caspase-3/7 Assay (n = 4). RESULTS While glucose-stimulated insulin secretion was decreased, there was no significant effect on apoptosis in human islets exposed to palmitate. We identified 1,860 differentially expressed genes in palmitate-treated human islets. These include candidate genes for T2D, such as TCF7L2, GLIS3, HNF1B and SLC30A8. Additionally, genes in glycolysis/gluconeogenesis, pyruvate metabolism, fatty acid metabolism, glutathione metabolism and one carbon pool by folate were differentially expressed in palmitate-treated human islets. Palmitate treatment altered the global DNA methylation level and DNA methylation levels of CpG island shelves and shores, 5'UTR, 3'UTR and gene body regions in human islets. Moreover, 290 genes with differential expression had a corresponding change in DNA methylation, for example, TCF7L2 and GLIS3. Importantly, out of the genes differentially expressed due to palmitate treatment in human islets, 67 were also associated with BMI and 37 were differentially expressed in islets from T2D patients. CONCLUSION Our study demonstrates that palmitate treatment of human pancreatic islets gives rise to epigenetic modifications that together with altered gene expression may contribute to impaired insulin secretion and T2D.
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Affiliation(s)
| | | | | | | | | | | | - Charlotte Ling
- Epigenetics and Diabetes Unit, Department of Clinical Sciences, Lund University Diabetes Centre, CRC, Lund University, Scania University Hospital, Malmö, Sweden.
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Steil GM, Grodsky GM. The artificial pancreas: is it important to understand how the β cell controls blood glucose? J Diabetes Sci Technol 2013; 7:1359-69. [PMID: 24124965 PMCID: PMC3876382 DOI: 10.1177/193229681300700528] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
It has been more than 7 years since the first fully automated closed-loop insulin delivery system that linked subcutaneous insulin delivery and glucose sensing was published. Since the initial report, the physiologic insulin delivery (PID) algorithm used to emulate the β cell has been modified from the original proportional-integral-derivative terms needed to fit the β cell's biphasic response to a hyperglycemic clamp to include terms emulating cephalic phase insulin release and the effect of insulin per se to inhibit insulin secretion. In this article, we compare the closed-loop glucose profiles obtained as each new term has been added, reassess the ability of the revised PID model to describe the β cells' insulin response to a hyperglycemic clamp, and look for the first time at its ability to describe the response to a hypoglycemic clamp. We also consider changes that might be added to the model based on perfused pancreas data. We conclude that the changes introduced in the PID model have systematically improved the closed-loop meal response. We note that the changes made do not adversely affect the ability of the model to fit hyperglycemic clamp data but are necessary to fit the response to a hypoglycemic clamp. Finally, we note a number of β cell characteristics observed in the perfused pancreas have not been included in the model. We suggest that continuing the effort to understand and incorporate aspects of how the β cell achieves glucose control can provide valuable insights into how improvements in future artificial pancreas algorithms might be achieved.
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Affiliation(s)
- Garry M Steil
- Boston Children's Hospital, Attn: Medicine Critical Care, 333 Longwood Ave., Boston, MA 022115.
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28
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Lundh M, Scully SS, Mandrup-Poulsen T, Wagner BK. Small-molecule inhibition of inflammatory β-cell death. Diabetes Obes Metab 2013; 15 Suppl 3:176-84. [PMID: 24003935 PMCID: PMC3777666 DOI: 10.1111/dom.12158] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 04/15/2013] [Indexed: 01/09/2023]
Abstract
With the worldwide increase in diabetes prevalence there is a pressing unmet need for novel antidiabetic therapies. Insufficient insulin production due to impaired β-cell function and apoptotic reduction of β-cell mass is a common denominator in the pathogenesis of diabetes. Current treatments are directed at improving insulin sensitivity, and stimulating insulin secretion or replacing the hormone, but do not target progressive apoptotic β-cell loss. Here we review the current development of small-molecule inhibitors designed to rescue β-cells from apoptosis. Several distinct classes of small molecules have been identified that protect β-cells from inflammatory, oxidative and/or metabolically induced apoptosis. Although none of these have yet reached the clinic, β-cell protective small molecules alone or in combination with current therapies provide exciting opportunities for the development of novel treatments for diabetes.
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Affiliation(s)
- Morten Lundh
- Chemical Biology Program, Broad Institute of Harvard and MIT, Cambridge, MA
- Department of Biomedical Sciences, University of Copenhagen, Denmark
| | - Stephen S. Scully
- Chemical Biology Program, Broad Institute of Harvard and MIT, Cambridge, MA
| | - Thomas Mandrup-Poulsen
- Department of Biomedical Sciences, University of Copenhagen, Denmark
- Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden
| | - Bridget K. Wagner
- Chemical Biology Program, Broad Institute of Harvard and MIT, Cambridge, MA
- Corresponding author: ; Broad Institute, 7 Cambridge Center, Cambridge, MA 02142; Tel: (617) 714-7363, Fax (617) 714-8943
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29
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Michaliszyn SF, Bonadonna RC, Sjaarda LA, Lee S, Farchoukh L, Arslanian SA. β-Cell lipotoxicity in response to free fatty acid elevation in prepubertal youth: African American versus Caucasian contrast. Diabetes 2013; 62:2917-22. [PMID: 23557704 PMCID: PMC3717834 DOI: 10.2337/db12-1664] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Prepubertal African American (AA) youth compared with their Caucasian (C) peers have higher insulin secretion, which correlates positively with free fatty acid (FFA) concentration. In our continued efforts to explain the racial disparity in insulinemia, and because FFAs modulate insulin secretion, we hypothesized that AA youth would have a greater response to FFA-induced β-cell insulin secretion than C youth. We compared the short-term effects of FFA elevation on fasting and glucose-stimulated C-peptide-modeled insulin secretion in prepubertal normal-weight AA versus C peers during a 2-h hyperglycemic clamp (12.5 mmol/L) on two occasions: 1) infusion of normal saline and 2) infusion of 20% intralipid (IL). During IL infusion, insulin sensitivity (IS) declined comparably in AA and C youth. Glucose sensitivity of first- and second-phase insulin secretion showed a significant condition × race interaction being higher in AA youth. Disposition index, β-cell function relative to IS, declined with IL infusion in AA and C youth, with a significantly greater decrease in Cs compared with AAs. In conclusion, AA and C prepubertal youth both demonstrated a decline in β-cell function relative to IS during IL infusion, indicative of acute lipotoxicity. The greater decline in C youth compared with AAs may suggest that C youth are more susceptible to β-cell lipotoxicity than AA youth, or alternatively, that AA youth are hypersensitive to FFA stimulation of β-cell insulin secretion, consistent with our theory.
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Affiliation(s)
- Sara F. Michaliszyn
- Division of Weight Management, Children’s Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Riccardo C. Bonadonna
- Division of Endocrinology and Metabolic Disease, University of Verona School of Medicine, and Azienda Ospedaliera Universitaria Integrata, Verona, Italy
| | - Lindsey A. Sjaarda
- Eunice Kennedy Shriver National Institute of Child Health & Human Development, National Institutes of Health, Bethesda, Maryland
| | - SoJung Lee
- Division of Weight Management, Children’s Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Lama Farchoukh
- Division of Weight Management, Children’s Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Silva A. Arslanian
- Division of Weight Management, Children’s Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
- Division of Pediatric Endocrinology, Metabolism & Diabetes Mellitus, Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania
- Corresponding author: Silva A. Arslanian,
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30
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Koulajian K, Ivovic A, Ye K, Desai T, Shah A, Fantus IG, Ran Q, Giacca A. Overexpression of glutathione peroxidase 4 prevents β-cell dysfunction induced by prolonged elevation of lipids in vivo. Am J Physiol Endocrinol Metab 2013; 305:E254-62. [PMID: 23695217 DOI: 10.1152/ajpendo.00481.2012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We have shown that oxidative stress is a mechanism of free fatty acid (FFA)-induced β-cell dysfunction. Unsaturated fatty acids in membranes, including plasma and mitochondrial membranes, are substrates for lipid peroxidation, and lipid peroxidation products are known to cause impaired insulin secretion. Therefore, we hypothesized that mice overexpressing glutathione peroxidase-4 (GPx4), an enzyme that specifically reduces lipid peroxides, are protected from fat-induced β-cell dysfunction. GPx4-overexpressing mice and their wild-type littermate controls were infused intravenously with saline or oleate for 48 h, after which reactive oxygen species (ROS) were imaged, using dihydrodichlorofluorescein diacetate in isolated islets, and β-cell function was assessed ex vivo in isolated islets and in vivo during hyperglycemic clamps. Forty-eight-hour FFA elevation in wild-type mice increased ROS and the lipid peroxidation product malondialdehyde and impaired β-cell function ex vivo in isolated islets and in vivo, as assessed by decreased disposition index. Also, islets of wild-type mice exposed to oleate for 48 h had increased ROS and lipid peroxides and decreased β-cell function. In contrast, GPx4-overexpressing mice showed no FFA-induced increase in ROS and lipid peroxidation and were protected from the FFA-induced impairment of β-cell function assessed in vitro, ex vivo and in vivo. These results implicate lipid peroxidation in FFA-induced β-cell dysfunction.
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Affiliation(s)
- Khajag Koulajian
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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Wagner R, Kaiser G, Gerst F, Christiansen E, Due-Hansen ME, Grundmann M, Machicao F, Peter A, Kostenis E, Ulven T, Fritsche A, Häring HU, Ullrich S. Reevaluation of fatty acid receptor 1 as a drug target for the stimulation of insulin secretion in humans. Diabetes 2013; 62:2106-11. [PMID: 23378609 PMCID: PMC3661642 DOI: 10.2337/db12-1249] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The role of free fatty acid receptor 1 (FFAR1/GPR40) in glucose homeostasis is still incompletely understood. Small receptor agonists stimulating insulin secretion are undergoing investigation for the treatment of type 2 diabetes. Surprisingly, genome-wide association studies did not discover diabetes risk variants in FFAR1. We reevaluated the role of FFAR1 in insulin secretion using a specific agonist, FFAR1-knockout mice and human islets. Nondiabetic individuals were metabolically phenotyped and genotyped. In vitro experiments indicated that palmitate and a specific FFAR1 agonist, TUG-469, stimulate glucose-induced insulin secretion through FFAR1. The proapoptotic effect of chronic exposure of β-cells to palmitate was independent of FFAR1. TUG-469 was protective, whereas inhibition of FFAR1 promoted apoptosis. In accordance with the proapoptotic effect of palmitate, in vivo cross-sectional observations demonstrated a negative association between fasting free fatty acids (NEFAs) and insulin secretion. Because NEFAs stimulate secretion through FFAR1, we examined the interaction of genetic variation in FFAR1 with NEFA and insulin secretion. The inverse association of NEFA and secretion was modulated by rs1573611 and became steeper for carriers of the minor allele. In conclusion, FFAR1 agonists support β-cell function, but variation in FFAR1 influences NEFA effects on insulin secretion and therefore could affect therapeutic efficacy of FFAR1 agonists.
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Affiliation(s)
- Robert Wagner
- University of Tübingen, Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, Tübingen, Germany
- Institute for Diabetes Research and Metabolic Diseases of the Helmholz Centre Munich at the University of Tübingen, Partner in the German Center for Diabetes Research, Tübingen, Germany
| | - Gabriele Kaiser
- University of Tübingen, Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, Tübingen, Germany
| | - Felicia Gerst
- University of Tübingen, Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, Tübingen, Germany
- Institute for Diabetes Research and Metabolic Diseases of the Helmholz Centre Munich at the University of Tübingen, Partner in the German Center for Diabetes Research, Tübingen, Germany
| | - Elisabeth Christiansen
- University of Southern Denmark, Department of Physics, Chemistry and Pharmacy, Odense M, Denmark
| | - Maria E. Due-Hansen
- University of Southern Denmark, Department of Physics, Chemistry and Pharmacy, Odense M, Denmark
| | - Manuel Grundmann
- University of Bonn, Institute for Pharmaceutical Biology, Bonn, Germany
| | - Fausto Machicao
- University of Tübingen, Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, Tübingen, Germany
- Institute for Diabetes Research and Metabolic Diseases of the Helmholz Centre Munich at the University of Tübingen, Partner in the German Center for Diabetes Research, Tübingen, Germany
| | - Andreas Peter
- University of Tübingen, Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, Tübingen, Germany
- Institute for Diabetes Research and Metabolic Diseases of the Helmholz Centre Munich at the University of Tübingen, Partner in the German Center for Diabetes Research, Tübingen, Germany
| | - Evi Kostenis
- University of Bonn, Institute for Pharmaceutical Biology, Bonn, Germany
| | - Trond Ulven
- University of Southern Denmark, Department of Physics, Chemistry and Pharmacy, Odense M, Denmark
| | - Andreas Fritsche
- University of Tübingen, Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, Tübingen, Germany
- Institute for Diabetes Research and Metabolic Diseases of the Helmholz Centre Munich at the University of Tübingen, Partner in the German Center for Diabetes Research, Tübingen, Germany
| | - Hans-Ulrich Häring
- University of Tübingen, Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, Tübingen, Germany
- Institute for Diabetes Research and Metabolic Diseases of the Helmholz Centre Munich at the University of Tübingen, Partner in the German Center for Diabetes Research, Tübingen, Germany
| | - Susanne Ullrich
- University of Tübingen, Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, Tübingen, Germany
- Institute for Diabetes Research and Metabolic Diseases of the Helmholz Centre Munich at the University of Tübingen, Partner in the German Center for Diabetes Research, Tübingen, Germany
- Corresponding author: Susanne Ullrich,
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Mukherjee B, Hossain CM, Mondal L, Paul P, Ghosh MK. Obesity and insulin resistance: an abridged molecular correlation. Lipid Insights 2013; 6:1-11. [PMID: 25278764 PMCID: PMC4147781 DOI: 10.4137/lpi.s10805] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
A relationship between obesity and type 2 diabetes is now generally well accepted. This relationship represents several major health hazards including morbid obesity and cardiovascular complications worldwide. Diabetes mellitus is a complex metabolic disorder characterized by impaired insulin release and insulin resistance. Lipids play an important physiological role in skeletal muscle, heart, liver and pancreas. Deregulation of fatty acid metabolism is the main culprit for developing insulin resistance and type 2 diabetes. A predominant predisposing factor to developing obesity, insulin resistance and type 2 diabetes is the permanent elevation of free fatty acids in plasma followed by impaired utilization of lipids by muscle. Diabetes-induced inflammation and oxidative stress have also vital role for development of insulin resistance in diabetic patients. The present review is intended to describe the correlation between lipids, obesity and insulin resistance based on current literature, in order to elucidate involved molecular mechanisms in depth.
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Affiliation(s)
- Biswajit Mukherjee
- Department of Pharmaceutical Technology, Jadavpur University, Kolkata, India
| | - Chowdhury M Hossain
- Department of Pharmaceutical Technology, Jadavpur University, Kolkata, India
| | - Laboni Mondal
- Department of Pharmaceutical Technology, Jadavpur University, Kolkata, India
| | - Paramita Paul
- Department of Pharmaceutical Technology, Jadavpur University, Kolkata, India
| | - Miltu K Ghosh
- Department of Pharmaceutical Technology, Jadavpur University, Kolkata, India
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Bissonnette S, Salem H, Wassef H, Saint-Pierre N, Tardif A, Baass A, Dufour R, Faraj M. Low density lipoprotein delays clearance of triglyceride-rich lipoprotein by human subcutaneous adipose tissue. J Lipid Res 2013; 54:1466-76. [PMID: 23417739 DOI: 10.1194/jlr.p023176] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Delayed clearance of triglyceride-rich lipoprotein (TRL) by white adipose tissue (WAT) promotes hypertriglyceridemia and elevated apoB-lipoproteins, which are primarily in the form of LDL. This study examines whether LDL promotes delayed clearance of TRL by WAT. Following the ingestion of a (13)C-triolein-labeled high-fat meal, obese women with high plasma apoB (> median 0.93 g/l, N = 11, > 98% as IDL/LDL) had delayed clearance of postprandial (13)C-triglyceride and (13)C-NEFA over 6 h compared with controls. AUC6 h of plasma (13)C-triglyceride and (13)C-NEFA correlated with plasma apoB but not with LDL diameter or adipocyte area. There was no group difference in (13)C-triolein oxidation rate, which suggests lower (13)C-NEFA storage in peripheral tissue in women with high apoB. Ex vivo/in vitro plasma apoB correlated negatively with WAT (3)H-lipid following a 4 h incubation of women's WAT with synthetic (3)H-triolein-TRL. LDL-differentiated 3T3-L1 adipocytes had lower (3)H-TRL hydrolysis and (3)H-NEFA storage. Treatment of women's WAT with their own LDL decreased (3)H-TRL hydrolysis and (3)H-NEFA uptake. Finally, LDL, although not an LPL substrate, reduced LPL-mediated (3)H-TRL hydrolysis as did VLDL and HDL. Exposure to LDL decreases TRL clearance by human WAT ex vivo. This may promote production of apoB-lipoproteins and hypertriglyceridemia through a positive-feedback mechanism in vivo.
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Affiliation(s)
- Simon Bissonnette
- Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
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Goldfine AB, Kulkarni RN. Modulation of β-cell function: a translational journey from the bench to the bedside. Diabetes Obes Metab 2012; 14 Suppl 3:152-60. [PMID: 22928576 DOI: 10.1111/j.1463-1326.2012.01647.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Both decreased insulin secretion and action contribute to the pathogenesis of type 2 diabetes (T2D) in humans. The insulin receptor and insulin signalling proteins are present in the rodent and human β-cell and modulate cell growth and function. Insulin receptors and insulin signalling proteins in β-cells are critical for compensatory islet growth in response to insulin resistance. Rodents with tissue-specific knockout of the insulin receptor in the β-cell (βIRKO) show reduced first-phase glucose-stimulated insulin secretion (GSIS) and with aging develop glucose intolerance and diabetes, phenotypically similar to the process seen in human T2D. Expression of multiple insulin signalling proteins is reduced in islets of patients with T2D. Insulin potentiates GSIS in isolated human β-cells. Recent studies in humans in vivo show that pre-exposure to insulin increases GSIS, and this effect is diminished in persons with insulin resistance or T2D. β-Cell function correlates to whole-body insulin sensitivity. Together, these findings suggest that pancreatic β-cell dysfunction could be caused by a defect in insulin signalling within β-cell, and β-cell insulin resistance may lead to a loss of β-cell function and/or mass, contributing to the pathophysiology of T2D.
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Affiliation(s)
- A B Goldfine
- Section of Clinical Research, Joslin Diabetes Center, Boston, MA 02215, USA.
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Tarabra E, Pelengaris S, Khan M. A simple matter of life and death-the trials of postnatal Beta-cell mass regulation. Int J Endocrinol 2012; 2012:516718. [PMID: 22577380 PMCID: PMC3346985 DOI: 10.1155/2012/516718] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 12/31/2011] [Indexed: 12/17/2022] Open
Abstract
Pancreatic beta-cells, which secrete the hormone insulin, are the key arbiters of glucose homeostasis. Defective beta-cell numbers and/or function underlie essentially all major forms of diabetes and must be restored if diabetes is to be cured. Thus, the identification of the molecular regulators of beta-cell mass and a better understanding of the processes of beta-cell differentiation and proliferation may provide further insight for the development of new therapeutic targets for diabetes. This review will focus on the principal hormones and nutrients, as well as downstream signalling pathways regulating beta-cell mass in the adult. Furthermore, we will also address more recently appreciated regulators of beta-cell mass, such as microRNAs.
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Affiliation(s)
- Elena Tarabra
- School of Life Sciences, Warwick University, Gibbet Hill Road, Coventry CV4 7AL, UK
- *Elena Tarabra:
| | - Stella Pelengaris
- School of Life Sciences, Warwick University, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Michael Khan
- School of Life Sciences, Warwick University, Gibbet Hill Road, Coventry CV4 7AL, UK
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Figueira TR, Ribeiro RA, Ignacio-Souza LM, Vercesi AE, Carneiro EM, Oliveira HCF. Enhanced insulin secretion and glucose tolerance in rats exhibiting low plasma free fatty acid levels and hypertriglyceridaemia due to congenital albumin deficiency. Exp Physiol 2011; 97:525-33. [PMID: 22198013 DOI: 10.1113/expphysiol.2011.062307] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Congenitally analbuminaemic individuals and rats (NARs) exhibit several metabolic abnormalities, including hypertriglyceridaemia and plasma free fatty acid deficiency. Our aim was to study glucose homeostasis and insulin secretion in NARs. Plasma concentrations of lipids, glucose and insulin and secretion of insulin from the pancreatic islets were measured in female NARs and control animals (Sprague-Dawley rats; SDRs). Glucose homeostasis tests were also performed. Plasma glucose levels were similar between NARs and SDRs, irrespective of feeding status. However, fed insulinaemia was ∼37% higher (P 0.05) in NARs than in SDRs. The NARs displayed a markedly increased glucose tolerance, i.e. the integrated glycaemic response was one-third that of the control animals. Enhanced glucose tolerance was associated with threefold higher insulinaemia at peak glycaemia after a glucose load than in the control animals. Similar peripheral insulin sensitivity was observed between groups. Isolated pancreatic islets from NARs secreted significantly more insulin than islets from SDRs in response to a wide range of glucose concentrations (2.8-33.3 mm). Despite having similar liver glycogen contents in the fully fed state, NARs had ∼40% (P 0.05) lower glycogen contents than SDRs after 6 h fasting. The injection of a gluconeogenic substrate, pyruvate, elicited a faster rise in glycaemia in NARs compared with SDRs. Overall, NARs displayed enhanced glucose tolerance, insulin secretion and gluconeogenic flux. The higher glucose tolerance in NARs compared with SDRs is attributed to enhanced islet responsiveness to secretagogues, while peripheral insulin sensitivity seems not to be involved in this alteration. We propose that the enhanced glucose metabolism is a chronic compensatory adaptation to decreased free fatty acid availability in NARs.
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Affiliation(s)
- Tiago R Figueira
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil
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Lopez X, Cypess A, Manning R, O'Shea S, Kulkarni RN, Goldfine AB. Exogenous insulin enhances glucose-stimulated insulin response in healthy humans independent of changes in free fatty acids. J Clin Endocrinol Metab 2011; 96:3811-21. [PMID: 21956413 PMCID: PMC3232618 DOI: 10.1210/jc.2011-0627] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Islet β-cells express both insulin receptors and insulin signaling proteins. Recent studies suggest insulin signaling is physiologically important for glucose sensing. OBJECTIVE Preexposure to insulin enhances glucose-stimulated insulin secretion (GSIS) in healthy humans. We evaluated whether the effect of insulin to potentiate GSIS is modulated through regulation of free fatty acids (FFA). DESIGN AND SETTING Subjects were studied on three occasions in this single-site study at an academic institution clinical research center. PATIENTS Subjects included nine healthy volunteers. INTERVENTIONS Glucose-induced insulin response was assessed on three occasions after 4 h saline (low insulin/sham) or isoglycemic-hyperinsulinemic (high insulin) clamps with or without intralipid and heparin infusion, using B28 Asp-insulin that could be distinguished from endogenous insulin immunologically. During the last 80 min of all three clamps, additional glucose was administered to stimulate insulin secretion (GSIS) with glucose concentrations maintained at similar concentrations during all studies. MAIN OUTCOME MEASURE β-Cell response to glucose stimulation was assessed. RESULTS Preexposure to exogenous insulin increased the endogenous insulin-secretory response to glucose by 32% compared with sham clamp (P = 0.001). This was accompanied by a drop in FFA during hyperinsulinemic clamp compared with the sham clamp (0.06 ± 0.02 vs. 0.60 ± 0.09 mEq/liter, respectively), which was prevented during the hyperinsulinemic clamp with intralipid/heparin infusion (1.27 ± 0.17 mEq/liter). After preexposure to insulin with intralipid/heparin infusion to maintain FFA concentration, GSIS was 21% higher compared with sham clamp (P < 0.04) and similar to preexposure to insulin without intralipid/heparin (P = 0.2). CONCLUSIONS Insulin potentiates glucose-stimulated insulin response independent of FFA concentrations in healthy humans.
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Affiliation(s)
- Ximena Lopez
- Joslin Diabetes Center and Harvard Medical School, Boston, Massachusetts 02215, USA
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Smiley D, Chandra P, Umpierrez GE. Update on diagnosis, pathogenesis and management of ketosis-prone Type 2 diabetes mellitus. ACTA ACUST UNITED AC 2011; 1:589-600. [PMID: 22611441 DOI: 10.2217/dmt.11.57] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Diabetic ketoacidosis (DKA) has been considered a key clinical feature of Type 1 diabetes mellitus; however, increasing evidence indicates that DKA is also a common feature of Type 2 diabetes (T2DM). Many cases of DKA develop under stressful conditions such as trauma or infection but an increasing number of cases without precipitating cause have been reported in children and adults with T2DM. Such patients present with severe hyperglycemia and ketosis as in Type 1 diabetes mellitus but can discontinue insulin after a few months and maintain acceptable glycemic control on diet or oral agents. This subtype of diabetes has been referred to as ketosis-prone T2DM. In this article, we reviewed the literature on ketosis-prone T2DM and summarized the epidemiology, putative pathophysiology and approaches to management.
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Affiliation(s)
- Dawn Smiley
- Emory University School of Medicine, Division of Endocrinology & Metabolism, Atlanta, GA 30303, USA
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Xiao C, Giacca A, Lewis GF. Short-term oral α-lipoic acid does not prevent lipid-induced dysregulation of glucose homeostasis in obese and overweight nondiabetic men. Am J Physiol Endocrinol Metab 2011; 301:E736-41. [PMID: 21750266 DOI: 10.1152/ajpendo.00183.2011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Prolonged elevation of plasma free fatty acids (FFAs) induces insulin resistance and impairs pancreatic β-cell adaptation to insulin resistance. The mechanisms whereby lipid induces these impairments are not fully defined but may involve oxidative stress, inflammation, and endoplasmic reticulum stress. α-Lipoic acid (ALA), a commonly used health supplement with antioxidant, anti-inflammatory, and AMPK-activating properties, has been shown to have therapeutic value in type 2 diabetes and its complications. Here we examined the effects of ALA on insulin sensitivity and secretion in humans under the conditions of 24-h iv lipid infusion to elevate plasma FFAs. Eight overweight and obese male subjects underwent four randomized studies each, 4-6 wk apart: 1) SAL, 2-wk oral placebo followed by 24-h iv infusion of saline; 2) IH, 2-wk placebo followed by 24-h iv infusion of intralipid plus heparin to raise plasma FFAs approximately twofold; 3) IH + ALA, 2-wk ALA (1,800 mg/day) followed by 24-h infusion of intralipid plus heparin; and 4) ALA, 2-wk ALA followed by 24-h infusion of saline. Insulin secretion rates (ISR) and insulin sensitivity were assessed with a 2-h, 20-mmol/l hyperglycemic clamp and a hyperinsulinemic euglycemic clamp, respectively. ISR was not significantly different between treatments. Lipid infusion impaired insulin sensitivity with and without ALA pretreatment. These results indicate that ALA, administered orally at this dose for 2 wk, does not protect against lipid-induced insulin resistance in overweight and obese humans.
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Affiliation(s)
- Changting Xiao
- Department of Medicine, University of Toronto, Ontario, Canada
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40
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Goree LL, Chandler-Laney P, Ellis AC, Casazza K, Granger WM, Gower BA. Dietary macronutrient composition affects β cell responsiveness but not insulin sensitivity. Am J Clin Nutr 2011; 94:120-7. [PMID: 21593507 PMCID: PMC3127518 DOI: 10.3945/ajcn.110.002162] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Altering dietary carbohydrate or fat content may have chronic effects on insulin secretion and sensitivity, which may vary with individual metabolic phenotype. OBJECTIVE The objective was to evaluate the contribution of tightly controlled diets differing in carbohydrate and fat content for 8 wk to insulin sensitivity and β cell responsiveness and whether effects of diet would vary with race, free-living diet, or insulin response. DESIGN Healthy overweight men and women (36 European Americans, 33 African Americans) were provided with food for 8 wk and received either a eucaloric standard diet (55% carbohydrate, 27% fat) or a eucaloric reduced-carbohydrate (RedCHO)/higher-fat diet (43% carbohydrate, 39% fat). Insulin sensitivity and β cell responsiveness were assessed at baseline and 8 wk by using a liquid meal tolerance test. RESULTS Insulin sensitivity did not change with diet (P = 0.1601). Static β cell response to glucose (ФS) was 28.5% lower after the RedCHO/higher-fat diet. Subgroup analyses indicated that lower ФS with the RedCHO/higher-fat diet occurred primarily among African Americans. A significant inverse association was observed for change in glucose area under the curve compared with change in ФS. CONCLUSIONS Consumption of a eucaloric 43% carbohydrate/39% fat diet for 8 wk resulted in down-regulation of β cell responsiveness, which was influenced by baseline phenotypic characteristics. Further study is needed to probe the potential cause-and-effect relation between change in ФS and change in glucose tolerance. This trial is registered at clinicaltrials.gov as NCT00726908.
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Affiliation(s)
- Laura Lee Goree
- Department of Nutrition Sciences at the University of Alabama at Birmingham, Birmingham, AL 35294-3360, USA
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Xiao C, Giacca A, Lewis GF. Sodium phenylbutyrate, a drug with known capacity to reduce endoplasmic reticulum stress, partially alleviates lipid-induced insulin resistance and beta-cell dysfunction in humans. Diabetes 2011; 60:918-24. [PMID: 21270237 PMCID: PMC3046853 DOI: 10.2337/db10-1433] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 12/12/2010] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Chronically elevated free fatty acids contribute to insulin resistance and pancreatic β-cell failure. Among numerous potential factors, the involvement of endoplasmic reticulum (ER) stress has been postulated to play a mechanistic role. Here we examined the efficacy of the chemical chaperone, sodium phenylbutyrate (PBA), a drug with known capacity to reduce ER stress in animal models and in vitro, on lipid-induced insulin resistance and β-cell dysfunction in humans. RESEARCH DESIGN AND METHODS Eight overweight or obese nondiabetic men underwent four studies each, in random order, 4 to 6 weeks apart. Two studies were preceded by 2 weeks of oral PBA (7.5 g/day), followed by a 48-h i.v. infusion of intralipid/heparin or saline, and two studies were preceded by placebo treatment, followed by similar infusions. Insulin secretion rates (ISRs) and sensitivity (S(I)) were assessed after the 48-h infusions by hyperglycemic and hyperinsulinemic-euglycemic clamps, respectively. RESULTS Lipid infusion reduced S(I), which was significantly ameliorated by pretreatment with PBA. Absolute ISR was not affected by any treatment; however, PBA partially ameliorated the lipid-induced reduction in the disposition index (DI = ISR × S(I)), indicating that PBA prevented lipid-induced β-cell dysfunction. CONCLUSIONS These results suggest that PBA may provide benefits in humans by ameliorating the insulin resistance and β-cell dysfunction induced by prolonged elevation of free fatty acids.
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Affiliation(s)
- Changting Xiao
- Departments of Medicine and Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Adria Giacca
- Departments of Medicine and Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Gary F. Lewis
- Departments of Medicine and Physiology, University of Toronto, Toronto, Ontario, Canada
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Giacca A, Xiao C, Oprescu AI, Carpentier AC, Lewis GF. Lipid-induced pancreatic β-cell dysfunction: focus on in vivo studies. Am J Physiol Endocrinol Metab 2011; 300:E255-62. [PMID: 21119027 DOI: 10.1152/ajpendo.00416.2010] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The phenomenon of lipid-induced pancreatic β-cell dysfunction ("lipotoxicity") has been very well documented in numerous in vitro experimental systems and has become widely accepted. In vivo demonstration of β-cell lipotoxicity, on the other hand, has not been consistently demonstrated, and there remains a lack of consensus regarding the in vivo effects of chronically elevated free fatty acids (FFA) on β-cell function. Much of the disagreement relates to how insulin secretion is quantified in vivo and in particular whether insulin secretion is assessed in relation to whole body insulin sensitivity, which is clearly reduced by elevated FFA. By correcting for changes in in vivo insulin sensitivity, we and others have shown that prolonged elevation of FFA impairs β-cell secretory function. Prediabetic animal models and humans with a positive family history of type 2 diabetes are more susceptible to this impairment, whereas those with severe impairment of β-cell function (such as individuals with type 2 diabetes) demonstrate no additional impairment of β-cell function when FFA are experimentally raised. Glucolipotoxicity (i.e., the combined β-cell toxicity of elevated glucose and FFA) has been amply demonstrated in vitro and in some animal studies but not in humans, perhaps because there are limitations in experimentally raising plasma glucose to sufficiently high levels for prolonged periods of time. We and others have shown that therapies directed toward diminishing oxidative stress and ER stress have the potential to reduce lipid-induced β-cell dysfunction in animals and humans. In conclusion, lipid-induced pancreatic β-cell dysfunction is likely to be one contributor to the complex array of genetic and metabolic insults that result in the relentless decline in pancreatic β-cell function in those destined to develop type 2 diabetes, and mechanisms involved in this lipotoxicity are promising therapeutic targets.
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Affiliation(s)
- Adria Giacca
- Dept. of Physiology, Univ. of Toronto, ON, Canada.
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Elsner M, Gehrmann W, Lenzen S. Peroxisome-generated hydrogen peroxide as important mediator of lipotoxicity in insulin-producing cells. Diabetes 2011; 60:200-8. [PMID: 20971967 PMCID: PMC3012172 DOI: 10.2337/db09-1401] [Citation(s) in RCA: 162] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Type 2 diabetes is a complex disease that is accompanied by elevated levels of nonesterified fatty acids (NEFAs), which contribute to β-cell dysfunction and β-cell loss, referred to as lipotoxicity. Experimental evidence suggests that oxidative stress is involved in lipotoxicity. In this study, we analyzed the molecular mechanisms of reactive oxygen species-mediated lipotoxicity in insulin-producing RINm5F cells and INS-1E cells as well as in primary rat islet cells. RESEARCH DESIGN AND METHODS The toxicity of saturated NEFAs with different chain lengths upon insulin-producing cells was determined by MTT and propidium iodide (PI) viability assays. Catalase or superoxide dismutase overexpressing cells were used to analyze the nature and the cellular compartment of reactive oxygen species formation. With the new H₂O₂-sensitive fluorescent protein HyPer H₂O₂ formation induced by exposure to palmitic acid was determined. RESULTS Only long-chain (>C14) saturated NEFAs were toxic to insulin-producing cells. Overexpression of catalase in the peroxisomes and in the cytosol, but not in the mitochondria, significantly reduced H₂O₂ formation and protected the cells against palmitic acid-induced toxicity. With the HyPer protein, H₂O₂ generation was directly detectable in the peroxisomes of RINm5F and INS-1E insulin-producing cells as well as in primary rat islet cells. CONCLUSIONS The results demonstrate that H₂O₂ formation in the peroxisomes rather than in the mitochondria are responsible for NEFA-induced toxicity. Therefore, we propose a new concept of fatty acid-induced β-cell lipotoxicity mediated via reactive oxygen species formation through peroxisomal β- oxidation.
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Affiliation(s)
- Matthias Elsner
- From the Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Wiebke Gehrmann
- From the Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Sigurd Lenzen
- From the Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
- Corresponding author: Sigurd Lenzen,
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Sato H, Carvalho G, Sato T, Bracco D, Codere-Maruyama T, Lattermann R, Hatzakorzian R, Matsukawa T, Schricker T. Perioperative tight glucose control with hyperinsulinemic-normoglycemic clamp technique in cardiac surgery. Nutrition 2010; 26:1122-9. [DOI: 10.1016/j.nut.2009.10.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Revised: 10/13/2009] [Accepted: 10/13/2009] [Indexed: 12/15/2022]
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Tarini J, Wolever TMS. The fermentable fibre inulin increases postprandial serum short-chain fatty acids and reduces free-fatty acids and ghrelin in healthy subjects. Appl Physiol Nutr Metab 2010; 35:9-16. [PMID: 20130660 DOI: 10.1139/h09-119] [Citation(s) in RCA: 209] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
It is thought that diets high in dietary fibre are associated with reduced risk for type 2 diabetes, at least in part because the short-chain fatty acids (SCFAs) produced during the colonic fermentation of fibre beneficially influence circulating concentrations of free-fatty acids (FFAs) and gut hormones involved in the regulation of blood glucose and body mass. However, there is a paucity of data showing this sequence of events in humans. Thus, our objective was to determine the effect of the fermentable fibre inulin on postprandial glucose, insulin, SCFA, FFA, and gut hormone responses in healthy subjects. Overnight fasted healthy subjects (n = 12) were studied for 6 h after consuming 400 mL drinks, containing 80 g high-fructose corn syrup (80HFCS), 56 g HFCS (56HFCS), or 56 g HFCS plus 24 g inulin (Inulin), using a randomized, single-blind, crossover design. A standard lunch was served 4 h after the test drink. Glucose and insulin responses after Inulin did not differ significantly from those after 80HFCS or 56HFCS. Serum acetate, propionate, and butyrate were significantly higher after Inulin than after HFCS drinks from 4-6 h. FFAs fell at a similar rate after all 3 test drinks, but were lower after Inulin than after 56HFCS at 4 h (0.40 +/- 0.06 vs. 0.51 +/- 0.06 mmol*L-1; p < 0.05). Compared with 56HFCS, Inulin significantly increased plasma glucagon-like peptide-1 concentrations at 30 min, and reduced ghrelin at 4.5 h and 6 h. The results are consistent with the hypothesis that dietary fibre increases the production of colonic SCFAs, which may reduce type 2 diabetes risk by reducing postprandial FFAs and favorably affecting gut hormones, which regulate food intake.
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Affiliation(s)
- Joshua Tarini
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON M5S 3E2, Canada
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Umpierrez GE, Smiley D, Robalino G, Peng L, Gosmanov AR, Kitabchi AE. Lack of lipotoxicity effect on {beta}-cell dysfunction in ketosis-prone type 2 diabetes. Diabetes Care 2010; 33:626-31. [PMID: 20028938 PMCID: PMC2827521 DOI: 10.2337/dc09-1369] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Over half of newly diagnosed obese African Americans with diabetic ketoacidosis (DKA) discontinue insulin therapy and go through a period of near-normoglycemia remission. This subtype of diabetes is known as ketosis-prone type 2 diabetes (KPDM). RESEARCH DESIGN AND METHODS To investigate the role of lipotoxicity on beta-cell function, eight obese African Americans with KPDM, eight obese subjects with type 2 diabetes with severe hyperglycemia without ketosis (ketosis-resistant type 2 diabetes), and nine nondiabetic obese control subjects underwent intravenous infusion of 20% intralipid at 40 ml/h for 48 h. beta-Cell function was assessed by changes in insulin and C-peptide concentration during infusions and by changes in acute insulin response to arginine stimulation (AIR(arg)) before and after lipid infusion. RESULTS The mean time to discontinue insulin therapy was 11.0 +/- 8.0 weeks in KPDM and 9.6 +/- 2.2 weeks in ketosis-resistant type 2 diabetes (P = NS). At remission, KPDM and ketosis-resistant type 2 diabetes had similar glucose (94 +/- 14 vs. 109 +/- 20 mg/dl), A1C (5.7 +/- 0.4 vs. 6.3 +/- 1.1%), and baseline AIR(arg) response (34.8 +/- 30 vs. 64 +/- 69 microU/ml). P = NS despite a fourfold increase in free fatty acid (FFA) levels (0.4 +/- 0.3 to 1.8 +/- 1.1 mmol/l, P < 0.01) during the 48-h intralipid infusion; the response to AIR(arg) stimulation, as well as changes in insulin and C-peptide levels, were similar among obese patients with KPDM, patients with ketosis-resistant type 2 diabetes, and nondiabetic control subjects. CONCLUSIONS Near-normoglycemia remission in obese African American patients with KPDM and ketosis-resistant type 2 diabetes is associated with a remarkable recovery in basal and stimulated insulin secretion. A high FFA level by intralipid infusion for 48 h was not associated with beta-cell decompensation (lipotoxicity) in KPDM patients.
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Insulin enhances glucose-stimulated insulin secretion in healthy humans. Proc Natl Acad Sci U S A 2010; 107:4770-5. [PMID: 20176932 DOI: 10.1073/pnas.1000002107] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Islet beta-cells express both insulin receptors and insulin-signaling proteins. Recent evidence from rodents in vivo and from islets isolated from rodents or humans suggests that the insulin signaling pathway is physiologically important for glucose sensing. We evaluated whether insulin regulates beta-cell function in healthy humans in vivo. Glucose-induced insulin secretion was assessed in healthy humans following 4-h saline (low insulin/sham clamp) or isoglycemic-hyperinsulinemic (high insulin) clamps using B28-Asp insulin that could be immunologically distinguished from endogenous insulin. Insulin and C-peptide clearance were evaluated to understand the impact of hyperinsulinemia on estimates of beta-cell function. Preexposure to exogenous insulin increased the endogenous insulin secretory response to glucose by approximately 40%. C-peptide response also increased, although not to the level predicted by insulin. Insulin clearance was not saturated at hyperinsulinemia, but metabolic clearance of C-peptide, assessed by infusion of stable isotope-labeled C-peptide, increased modestly during hyperinsulinemic clamp. These studies demonstrate that insulin potentiates glucose-stimulated insulin secretion in vivo in healthy humans. In addition, hyperinsulinemia increases C-peptide clearance, which may lead to modest underestimation of beta-cell secretory response when using these methods during prolonged dynamic testing.
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Xiao C, Giacca A, Lewis GF. The effect of high-dose sodium salicylate on chronically elevated plasma nonesterified fatty acid-induced insulin resistance and β-cell dysfunction in overweight and obese nondiabetic men. Am J Physiol Endocrinol Metab 2009; 297:E1205-11. [PMID: 19755670 DOI: 10.1152/ajpendo.00313.2009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Prolonged elevation of plasma nonesterified fatty acids (NEFA) induces insulin resistance and impairs pancreatic β-cell adaptation to insulin resistance. Studies in rodents suggest that inflammation may play a role in this "lipotoxicity." We studied the effects of sodium salicylate, an anti-inflammatory agent, on lipid-induced alterations in β-cell function and insulin sensitivity in six overweight and obese nondiabetic men. Each subject underwent four separate studies, 4-6 wk apart, in random order: 1) SAL, 1-wk placebo followed by intravenous (iv) infusion of saline for 48 h; 2) IH, 1-wk placebo followed by iv infusion of intralipid plus heparin for 48 h to raise plasma NEFA approximately twofold; 3) IH + SS, 1-wk sodium salicylate (4.5 g/day) followed by 48-h IH infusion; and 4) SS, 1-wk oral sodium salicylate followed by 48-h saline infusion. After 48-h saline or lipid infusion, insulin secretion and sensitivity were assessed by hyperglycemic clamp and euglycemic hyperinsulinemic clamp, respectively, in sequential order. Insulin sensitivity was reduced by lipid infusion (IH = 67% of SAL) and was not improved by salicylate (IH + SS = 56% of SAL). Lipid infusion also reduced the disposition index (P < 0.05), which was not prevented by sodium salicylate. Salicylate reduced insulin clearance. These data suggest that oral sodium salicylate at this dose impairs insulin clearance but does not ameliorate lipid-induced insulin resistance and β-cell dysfunction in overweight and obese nondiabetic men.
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Affiliation(s)
- Changting Xiao
- Departments of Medicine and Physiology, University of Toronto, Toronto, Ontario, Canada
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Poitout V, Amyot J, Semache M, Zarrouki B, Hagman D, Fontés G. Glucolipotoxicity of the pancreatic beta cell. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1801:289-98. [PMID: 19715772 DOI: 10.1016/j.bbalip.2009.08.006] [Citation(s) in RCA: 264] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 08/13/2009] [Accepted: 08/13/2009] [Indexed: 02/07/2023]
Abstract
The concept of glucolipotoxicity refers to the combined, deleterious effects of elevated glucose and fatty acid levels on pancreatic beta-cell function and survival. Significant progress has been made in recent years towards a better understanding of the cellular and molecular basis of glucolipotoxicity in the beta cell. The permissive effect of elevated glucose on the detrimental actions of fatty acids stems from the influence of glucose on intracellular fatty acid metabolism, promoting the synthesis of cellular lipids. The combination of excessive levels of fatty acids and glucose therefore leads to decreased insulin secretion, impaired insulin gene expression, and beta-cell death by apoptosis, all of which probably have distinct underlying mechanisms. Recent studies from our laboratory have identified several pathways implicated in fatty acid inhibition of insulin gene expression, including the extracellular-regulated kinase (ERK1/2) pathway, the metabolic sensor Per-Arnt-Sim kinase (PASK), and the ATF6 branch of the unfolded protein response. We have also confirmed in vivo in rats that the decrease in insulin gene expression is an early defect which precedes any detectable abnormality in insulin secretion. While the role of glucolipotoxicity in humans is still debated, the inhibitory effects of chronically elevated fatty acid levels has been clearly demonstrated in several studies, at least in individuals genetically predisposed to developing type 2 diabetes. It is therefore likely that glucolipotoxicity contributes to beta-cell failure in type 2 diabetes as well as to the decline in beta-cell function observed after the onset of the disease.
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Affiliation(s)
- Vincent Poitout
- Montreal Diabetes Research Center, CRCHUM, Department of Medicine, University of Montreal, Montreal, QC, Canada.
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