1
|
Coloretti I, Genovese A, Teixeira JP, Cherian A, Ferrer R, Landoni G, Leone M, Girardis M, Nielsen ND. Angiotensin ii therapy in refractory septic shock: which patient can benefit most? A narrative review. JOURNAL OF ANESTHESIA, ANALGESIA AND CRITICAL CARE 2024; 4:13. [PMID: 38383521 PMCID: PMC10882873 DOI: 10.1186/s44158-024-00150-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 02/12/2024] [Indexed: 02/23/2024]
Abstract
Patients with septic shock who experience refractory hypotension despite adequate fluid resuscitation and high-dose noradrenaline have high mortality rates. To improve outcomes, evidence-based guidelines recommend starting a second vasopressor, such as vasopressin, if noradrenaline doses exceed 0.5 µg/kg/min. Recently, promising results have been observed in treating refractory hypotension with angiotensin II, which has been shown to increase mean arterial pressure and has been associated with improved outcomes. This narrative review aims to provide an overview of the pathophysiology of the renin-angiotensin system and the role of endogenous angiotensin II in vasodilatory shock with a focus on how angiotensin II treatment impacts clinical outcomes and on identifying the population that may benefit most from its use.
Collapse
Affiliation(s)
- Irene Coloretti
- Anesthesia and Intensive Care Medicine, Policlinico Di Modena, University of Modena and Reggio Emilia, Via del Pozzo, Modena, 71. 41124, Italy.
| | - Andrea Genovese
- Anesthesia and Intensive Care Medicine, Policlinico Di Modena, University of Modena and Reggio Emilia, Via del Pozzo, Modena, 71. 41124, Italy
| | - J Pedro Teixeira
- Divisions of Nephrology and Pulmonary, Critical Care, and Sleep Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Anusha Cherian
- Anesthesiology and Critical Care, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Dhanvantri Nagar, Pondicherry, India
| | - Ricard Ferrer
- Intensive Care Department, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Giovanni Landoni
- Anesthesia and Intensive Care, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Marc Leone
- Anesthesia and Intensive Care Medicine, Hôpital Nord, Assistance Publique Hôpitaux de Marseille, Aix Marseille Université, Marseille, France
| | - Massimo Girardis
- Anesthesia and Intensive Care Medicine, Policlinico Di Modena, University of Modena and Reggio Emilia, Via del Pozzo, Modena, 71. 41124, Italy
| | - Nathan D Nielsen
- Division of Pulmonary, Critical Care and Sleep Medicine & Section of Transfusion Medicine and Therapeutic Pathology, University of New Mexico School of Medicine, Albuquerque, NM, USA
| |
Collapse
|
2
|
Zamolodchikova TS, Tolpygo SM, Kotov AV. Insulin in the regulation of the renin-angiotensin system: a new perspective on the mechanism of insulin resistance and diabetic complications. Front Endocrinol (Lausanne) 2024; 15:1293221. [PMID: 38323106 PMCID: PMC10844507 DOI: 10.3389/fendo.2024.1293221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 01/08/2024] [Indexed: 02/08/2024] Open
|
3
|
Ashik T, Lee V, Atanes P, Persaud SJ. Alterations in mouse visceral adipose tissue mRNA expression of islet G-protein-coupled receptor ligands in obesity. Diabet Med 2022; 39:e14978. [PMID: 36245259 PMCID: PMC9828549 DOI: 10.1111/dme.14978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/04/2022] [Accepted: 10/14/2022] [Indexed: 01/18/2023]
Abstract
BACKGROUND Adipose tissue mass expansion in obesity leads to alterations in expression and secretion of adipokines, some of which may alter islet function by binding to G-protein-coupled receptors (GPCRs) expressed by islets. We have therefore quantified expression of mRNAs encoding islet GPCR ligands in visceral adipose tissue retrieved from lean and diet-induced obese mice to determine alterations in islet GPCR ligand mRNAs in obesity. METHODS Epididymal adipose tissue was retrieved from C57BL/6 mice that had been maintained on a control-fat diet (10% fat) or high-fat diet (60% fat) for 16 weeks and RT-qPCR was used to quantify mRNAs encoding ligands for islet GPCRs. RESULTS Of the 155 genes that encode ligands for islet GPCRs, 45 and 40 were expressed in visceral adipose tissue retrieved from lean and obese mice respectively. The remaining mRNAs were either expressed at trace level (0.0001% to 0.001% relative to Actb expression) or absent (<0.0001%). Obesity was associated with significant alterations in GPCR ligand mRNA expression in visceral adipose tissue, some of which encode for peptides with established effects on islet function (e.g. neuropeptide Y), or for GPCR ligands that have not previously been investigated for their effects on islets (e.g. (C-C motif) ligand 4; Ccl4). CONCLUSION Mouse visceral adipose tissue showed significant alterations in expression of mRNAs encoding islet GPCR ligands in obesity. Our data point to ligands of interest for future research on adipose-islet crosstalk via secreted ligands acting at islet GPCRs. Such research may identify islet GPCRs with therapeutic potential for T2D.
Collapse
Affiliation(s)
- Tanyel Ashik
- Department of Diabetes, School of Cardiovascular and Metabolic Medicine & SciencesKing's College LondonLondonUK
| | - Vivian Lee
- Department of Diabetes, School of Cardiovascular and Metabolic Medicine & SciencesKing's College LondonLondonUK
| | - Patricio Atanes
- Department of Diabetes, School of Cardiovascular and Metabolic Medicine & SciencesKing's College LondonLondonUK
| | - Shanta J. Persaud
- Department of Diabetes, School of Cardiovascular and Metabolic Medicine & SciencesKing's College LondonLondonUK
| |
Collapse
|
4
|
Biondi G, Marrano N, Borrelli A, Rella M, Palma G, Calderoni I, Siciliano E, Lops P, Giorgino F, Natalicchio A. Adipose Tissue Secretion Pattern Influences β-Cell Wellness in the Transition from Obesity to Type 2 Diabetes. Int J Mol Sci 2022; 23:ijms23105522. [PMID: 35628332 PMCID: PMC9143684 DOI: 10.3390/ijms23105522] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 12/10/2022] Open
Abstract
The dysregulation of the β-cell functional mass, which is a reduction in the number of β-cells and their ability to secure adequate insulin secretion, represents a key mechanistic factor leading to the onset of type 2 diabetes (T2D). Obesity is recognised as a leading cause of β-cell loss and dysfunction and a risk factor for T2D. The natural history of β-cell failure in obesity-induced T2D can be divided into three steps: (1) β-cell compensatory hyperplasia and insulin hypersecretion, (2) insulin secretory dysfunction, and (3) loss of β-cell mass. Adipose tissue (AT) secretes many hormones/cytokines (adipokines) and fatty acids that can directly influence β-cell function and viability. As this secretory pattern is altered in obese and diabetic patients, it is expected that the cross-talk between AT and pancreatic β-cells could drive the maintenance of the β-cell integrity under physiological conditions and contribute to the reduction in the β-cell functional mass in a dysmetabolic state. In the current review, we summarise the evidence of the ability of the AT secretome to influence each step of β-cell failure, and attempt to draw a timeline of the alterations in the adipokine secretion pattern in the transition from obesity to T2D that reflects the progressive deterioration of the β-cell functional mass.
Collapse
|
5
|
Premilovac D, Attrill E, Rattigan S, Richards SM, Kim J, Keske MA. Acute, local infusion of angiotensin II impairs microvascular and metabolic insulin sensitivity in skeletal muscle. Cardiovasc Res 2020; 115:590-601. [PMID: 30192915 DOI: 10.1093/cvr/cvy225] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 07/30/2018] [Accepted: 09/04/2018] [Indexed: 12/11/2022] Open
Abstract
AIMS Angiotensin II (AngII) is a potent vasoconstrictor implicated in both hypertension and insulin resistance. Insulin dilates the vasculature in skeletal muscle to increase microvascular blood flow and enhance glucose disposal. In the present study, we investigated whether acute AngII infusion interferes with insulin's microvascular and metabolic actions in skeletal muscle. METHODS AND RESULTS Adult, male Sprague-Dawley rats received a systemic infusion of either saline, AngII, insulin (hyperinsulinaemic euglycaemic clamp), or insulin (hyperinsulinaemic euglycaemic clamp) plus AngII. A final, separate group of rats received an acute local infusion of AngII into a single hindleg during systemic insulin (hyperinsulinaemic euglycaemic clamp) infusion. In all animals' systemic metabolic effects, central haemodynamics, femoral artery blood flow, microvascular blood flow, and skeletal muscle glucose uptake (isotopic glucose) were monitored. Systemic AngII infusion increased blood pressure, decreased heart rate, and markedly increased circulating glucose and insulin concentrations. Systemic infusion of AngII during hyperinsulinaemic euglycaemic clamp inhibited insulin-mediated suppression of hepatic glucose output and insulin-stimulated microvascular blood flow in skeletal muscle but did not alter insulin's effects on the femoral artery or muscle glucose uptake. Local AngII infusion did not alter blood pressure, heart rate, or circulating glucose and insulin. However, local AngII inhibited insulin-stimulated microvascular blood flow, and this was accompanied by reduced skeletal muscle glucose uptake. CONCLUSIONS Acute infusion of AngII significantly alters basal haemodynamic and metabolic homeostasis in rats. Both local and systemic AngII infusion attenuated insulin's microvascular actions in skeletal muscle, but only local AngII infusion led to reduced insulin-stimulated muscle glucose uptake. While increased local, tissue production of AngII may be a factor that couples microvascular insulin resistance and hypertension, additional studies are needed to determine the molecular mechanisms responsible for these vascular defects.
Collapse
Affiliation(s)
- Dino Premilovac
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia.,School of Medicine, University of Tasmania, Hobart, TAS, Australia
| | - Emily Attrill
- School of Medicine, University of Tasmania, Hobart, TAS, Australia
| | - Stephen Rattigan
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
| | - Stephen M Richards
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia.,School of Medicine, University of Tasmania, Hobart, TAS, Australia
| | - Jeonga Kim
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Michelle A Keske
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia.,Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, Australia
| |
Collapse
|
6
|
Ramalingam L, Sopontammarak B, Menikdiwela KR, Moustaid-Moussa N. Endoplasmic Reticulum (ER) Stress in Part Mediates Effects of Angiotensin II in Pancreatic Beta Cells. Diabetes Metab Syndr Obes 2020; 13:2843-2853. [PMID: 32884312 PMCID: PMC7443445 DOI: 10.2147/dmso.s257797] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 06/24/2020] [Indexed: 12/22/2022] Open
Abstract
INTRODUCTION The renin angiotensin aldosterone system (RAAS) is a hormone system known for its role in regulating blood pressure and fluid balance. Numerous RAAS inhibitors routinely prescribed for hypertension have also beneficial effects in type 2 diabetes (T2D) prevention. RAAS components are expressed locally in many tissues, including adipose tissue and pancreas, where they exert metabolic effects through RAAS bioactive hormone angiotensin II (Ang II). Pancreatic beta cells are specialized insulin-producing cells; they have also developed endoplasmic reticulum (ER), which contributes to beta cell dysfunction, when proteins are misfolded in disease states such as T2D. However, no studies have investigated the relationship between RAAS and ER stress in beta cells as a mechanism linking pancreatic RAAS to T2D. Hence, we hypothesized that Ang II treatment of beta cells increases ER stress and inflammation leading to reduced insulin secretion. METHODS To test this hypothesis, we treated clonal INS-1E beta cells and human islets with Ang II and assessed changes in ER stress markers. INS-1E beta cells were also used for measuring insulin secretion and for assessing the effects of various RAAS and ER stress inhibitors. RESULTS We demonstrated that Ang II significantly increased the expression of ER stress genes such as Chop and Atf4 and reduced insulin secretion. Furthermore, inhibition of Ang II production with an angiotensin converting enzyme inhibitor (ACEi, captopril) significantly reduced ER stress. Moreover, the Ang II receptor blockade reduced ER stress significantly and rescued insulin secretion. DISCUSSION This research provides new mechanistic insight into the role of RAAS activation via ER stress on beta cell dysfunction and provides additional evidence for protective effects of RAAS inhibition in T2D.
Collapse
Affiliation(s)
- Latha Ramalingam
- Department of Nutritional Sciences, And Obesity Research Institute, Texas Tech University, Lubbock, TX79424, USA
| | - Boontharick Sopontammarak
- Department of Nutritional Sciences, And Obesity Research Institute, Texas Tech University, Lubbock, TX79424, USA
| | - Kalhara R Menikdiwela
- Department of Nutritional Sciences, And Obesity Research Institute, Texas Tech University, Lubbock, TX79424, USA
| | - Naima Moustaid-Moussa
- Department of Nutritional Sciences, And Obesity Research Institute, Texas Tech University, Lubbock, TX79424, USA
- Correspondence: Naima Moustaid-Moussa Texas Tech University, Department of Nutritional Sciences & Obesity Research Institute, 1301 Akron Street, Lubbock, TX79409-1270, USATel + 806-834-7946 Email
| |
Collapse
|
7
|
Hwang HJ, Jang HJ, Cocco L, Suh PG. The regulation of insulin secretion via phosphoinositide-specific phospholipase Cβ signaling. Adv Biol Regul 2019; 71:10-18. [PMID: 30293894 DOI: 10.1016/j.jbior.2018.09.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 09/17/2018] [Accepted: 09/17/2018] [Indexed: 06/08/2023]
Abstract
Phospholipase Cβ (PLCβ) is a membrane-associated enzyme activated by membrane receptors, especially G-protein coupled receptors (GPCRs). It propagates intracellular signaling by mediating phospholipid metabolism and generating key second messengers, such as inositol triphosphate and diacylglycerol, leading to intracellular Ca2+ mobilization and activation of kinases, such as protein kinases C. In pancreatic β-cells, PLCβ-mediated signaling activated by various factors, such as free fatty acids and neuronal and hormonal ligands, has been confirmed as being involved in the regulation of insulin secretion, and PLCβs have been regarded as essential mediators for augmenting insulin secretion. In this review, we describe the physiological function of PLCβs in the regulation of glucose-stimulated insulin secretion and discuss emerging data on GPCR/PLCβ signaling that is being developed as a target for the treatment of diabetes mellitus.
Collapse
Affiliation(s)
- Hyeon-Jeong Hwang
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Hyun-Jun Jang
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Lucio Cocco
- Cellular Signaling Laboratory, Department of Biomedical Sciences, University of Bologna, Via Irnerio, 48, I-40126, Bologna, Italy
| | - Pann-Ghill Suh
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.
| |
Collapse
|
8
|
Olaniru OE, Pingitore A, Giera S, Piao X, Castañera González R, Jones PM, Persaud SJ. The adhesion receptor GPR56 is activated by extracellular matrix collagen III to improve β-cell function. Cell Mol Life Sci 2018; 75:4007-4019. [PMID: 29855662 PMCID: PMC6182347 DOI: 10.1007/s00018-018-2846-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 05/11/2018] [Accepted: 05/24/2018] [Indexed: 12/19/2022]
Abstract
AIMS G-protein coupled receptor 56 (GPR56) is the most abundant islet-expressed G-protein coupled receptor, suggesting a potential role in islet function. This study evaluated islet expression of GPR56 and its endogenous ligand collagen III, and their effects on β-cell function. METHODS GPR56 and collagen III expression in mouse and human pancreas sections was determined by fluorescence immunohistochemistry. Effects of collagen III on β-cell proliferation, apoptosis, intracellular calcium ([Ca2+]i) and insulin secretion were determined by cellular BrdU incorporation, caspase 3/7 activities, microfluorimetry and radioimmunoassay, respectively. The role of GPR56 in islet vascularisation and innervation was evaluated by immunohistochemical staining for CD31 and TUJ1, respectively, in pancreases from wildtype (WT) and Gpr56-/- mice, and the requirement of GPR56 for normal glucose homeostasis was determined by glucose tolerance tests in WT and Gpr56-/- mice. RESULTS Immunostaining of mouse and human pancreases revealed that GPR56 was expressed by islet β-cells while collagen III was confined to the peri-islet basement membrane and islet capillaries. Collagen III protected β-cells from cytokine-induced apoptosis, triggered increases in [Ca2+]i and potentiated glucose-induced insulin secretion from WT islets but not from Gpr56-/- islets. Deletion of GPR56 did not affect glucose-induced insulin secretion in vitro and it did not impair glucose tolerance in adult mice. GPR56 was not required for normal islet vascularisation or innervation. CONCLUSION We have demonstrated that collagen III improves islet function by increasing insulin secretion and protecting against apoptosis. Our data suggest that collagen III may be effective in optimising islet function to improve islet transplantation outcomes, and GPR56 may be a target for the treatment of type 2 diabetes.
Collapse
Affiliation(s)
- Oladapo E Olaniru
- Department of Diabetes, School of Life Course Sciences, King's College London, Guy's Campus, London, SE1 1UL, UK
| | - Attilio Pingitore
- Department of Diabetes, School of Life Course Sciences, King's College London, Guy's Campus, London, SE1 1UL, UK
| | - Stefanie Giera
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, USA
| | - Xianhua Piao
- Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA, 02115, USA
| | - Ramón Castañera González
- Department of General Surgery, Rio Carrión Hospital, University Hospital Complex of Palencia, Palencia, Spain
| | - Peter M Jones
- Department of Diabetes, School of Life Course Sciences, King's College London, Guy's Campus, London, SE1 1UL, UK
| | - Shanta J Persaud
- Department of Diabetes, School of Life Course Sciences, King's College London, Guy's Campus, London, SE1 1UL, UK.
| |
Collapse
|
9
|
Phuong HTA, Yu L, Park BM, Kim SH. Comparative effects of angiotensin II and angiotensin-(4-8) on blood pressure and ANP secretion in rats. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2017; 21:667-674. [PMID: 29200910 PMCID: PMC5709484 DOI: 10.4196/kjpp.2017.21.6.667] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 07/26/2017] [Accepted: 08/07/2017] [Indexed: 12/16/2022]
Abstract
Angiotensin II (Ang II) is metabolized from N-terminal by aminopeptidases and from C-terminal by Ang converting enzyme (ACE) to generate several truncated angiotensin peptides (Angs). The truncated Angs have different biological effects but it remains unknown whether Ang-(4-8) is an active peptide. The present study was to investigate the effects of Ang-(4-8) on hemodynamics and atrial natriuretic peptide (ANP) secretion using isolated beating rat atria. Atrial stretch caused increases in atrial contractility by 60% and in ANP secretion by 70%. Ang-(4-8) (0.01, 0.1, and 1 µM) suppressed high stretch-induced ANP secretion in a dose-dependent manner. Ang-(4-8) (0.1 µM)-induced suppression of ANP secretion was attenuated by the pretreatment with an antagonist of Ang type 1 receptor (AT1R) but not by an antagonist of AT2R or AT4R. Ang-(4-8)-induced suppression of ANP secretion was attenuated by the pretreatment with inhibitor of phospholipase (PLC), inositol triphosphate (IP3) receptor, or nonspecific protein kinase C (PKC). The potency of Ang-(4-8) to inhibit ANP secretion was similar to Ang II. However, Ang-(4-8) 10 µM caused an increased mean arterial pressure which was similar to that by 1 nM Ang II. Therefore, we suggest that Ang-(4-8) suppresses high stretch-induced ANP secretion through the AT1R and PLC/IP3/PKC pathway. Ang-(4-8) is a biologically active peptide which functions as an inhibition mechanism of ANP secretion and an increment of blood pressure.
Collapse
Affiliation(s)
- Hoang Thi Ai Phuong
- Department of Physiology, Research Institute for Endocrine Sciences, Chonbuk National University Medical School, Jeonju 54907, Korea
| | - Lamei Yu
- Department of Physiology, Research Institute for Endocrine Sciences, Chonbuk National University Medical School, Jeonju 54907, Korea
| | - Byung Mun Park
- Department of Physiology, Research Institute for Endocrine Sciences, Chonbuk National University Medical School, Jeonju 54907, Korea
| | - Suhn Hee Kim
- Department of Physiology, Research Institute for Endocrine Sciences, Chonbuk National University Medical School, Jeonju 54907, Korea
| |
Collapse
|
10
|
Pingitore A, Chambers ES, Hill T, Maldonado IR, Liu B, Bewick G, Morrison DJ, Preston T, Wallis GA, Tedford C, Castañera González R, Huang GC, Choudhary P, Frost G, Persaud SJ. The diet-derived short chain fatty acid propionate improves beta-cell function in humans and stimulates insulin secretion from human islets in vitro. Diabetes Obes Metab 2017; 19:257-265. [PMID: 27761989 DOI: 10.1111/dom.12811] [Citation(s) in RCA: 160] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/13/2016] [Accepted: 10/14/2016] [Indexed: 12/18/2022]
Abstract
AIMS Diet-derived short chain fatty acids (SCFAs) improve glucose homeostasis in vivo, but the role of individual SCFAs and their mechanisms of action have not been defined. This study evaluated the effects of increasing colonic delivery of the SCFA propionate on β-cell function in humans and the direct effects of propionate on isolated human islets in vitro. MATERIALS AND METHODS For 24 weeks human subjects ingested an inulin-propionate ester that delivers propionate to the colon. Acute insulin, GLP-1 and non-esterified fatty acid (NEFA) levels were quantified pre- and post-supplementation in response to a mixed meal test. Expression of the SCFA receptor FFAR2 in human islets was determined by western blotting and immunohistochemistry. Dynamic insulin secretion from perifused human islets was quantified by radioimmunoassay and islet apoptosis was determined by quantification of caspase 3/7 activities. RESULTS Colonic propionate delivery in vivo was associated with improved β-cell function with increased insulin secretion that was independent of changes in GLP-1 levels. Human islet β-cells expressed FFAR2 and propionate potentiated dynamic glucose-stimulated insulin secretion in vitro, an effect that was dependent on signalling via protein kinase C. Propionate also protected human islets from apoptosis induced by the NEFA sodium palmitate and inflammatory cytokines. CONCLUSIONS Our results indicate that propionate has beneficial effects on β-cell function in vivo, and in vitro analyses demonstrated that it has direct effects to potentiate glucose-stimulated insulin release and maintain β-cell mass through inhibition of apoptosis. These observations support ingestion of propiogenic dietary fibres to maintain healthy glucose homeostasis.
Collapse
Affiliation(s)
- Attilio Pingitore
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Edward S Chambers
- Faculty of Medicine, Nutrition and Dietetic Research Group, Imperial College London, London, UK
| | - Thomas Hill
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Inmaculada Ruz Maldonado
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Bo Liu
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Gavin Bewick
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Douglas J Morrison
- Stable Isotope Biochemistry Laboratory, Scottish Universities Environmental Research Centre, University of Glasgow, Glasgow, UK
| | - Tom Preston
- Stable Isotope Biochemistry Laboratory, Scottish Universities Environmental Research Centre, University of Glasgow, Glasgow, UK
| | - Gareth A Wallis
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | - Catriona Tedford
- School of Science, University of the West of Scotland, Hamilton, UK
| | - Ramón Castañera González
- Department of General Surgery, Rio Carrión Hospital, University Hospital Complex of Palencia, Palencia, Spain
| | - Guo C Huang
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Pratik Choudhary
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Gary Frost
- Faculty of Medicine, Nutrition and Dietetic Research Group, Imperial College London, London, UK
| | - Shanta J Persaud
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| |
Collapse
|
11
|
Shoemaker R, Yiannikouris F, Thatcher S, Cassis L. ACE2 deficiency reduces β-cell mass and impairs β-cell proliferation in obese C57BL/6 mice. Am J Physiol Endocrinol Metab 2015; 309:E621-31. [PMID: 26389599 PMCID: PMC4593774 DOI: 10.1152/ajpendo.00054.2015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 07/31/2015] [Indexed: 12/13/2022]
Abstract
Drugs that inhibit the renin-angiotensin system (RAS) decrease the onset of type 2 diabetes (T2D). Pancreatic islets express RAS components, including angiotensin-converting enzyme 2 (ACE2), which cleaves angiotensin II (Ang II) to angiotensin-(1-7) [Ang-(1-7)]. Overexpression of ACE2 in pancreas of diabetic mice improved glucose homeostasis. The purpose of this study was to determine if deficiency of endogenous ACE2 contributes to islet dysfunction and T2D. We hypothesized that ACE2 deficiency potentiates the decline in β-cell function and augments the development of diet-induced T2D. Male Ace2(+/y) or Ace2(-/y) mice were fed a low-fat (LF) or high-fat (HF) diet for 1 or 4 mo. A subset of 1-mo HF-fed mice were infused with Sal (Sal), losartan (Los), or Ang-(1-7). At 4 mo, while both genotypes of HF-fed mice developed a similar level of insulin resistance, adaptive hyperinsulinemia was reduced in Ace2(-/y) vs. Ace2(+/y) mice. Similarly, in vivo glucose-stimulated insulin secretion (GSIS) was reduced in 1-mo HF-fed Ace2(-/y) compared with Ace2(+/y) mice, resulting in augmented hyperglycemia. The average islet area was significantly smaller in both LF- and HF-fed Ace2(-/y) vs. Ace2(+/y) mice. Additionally, β-cell mass and proliferation were reduced significantly in HF-fed Ace2(-/y) vs. Ace2(+/y) mice. Neither infusion of Los nor Ang-(1-7) was able to correct impaired in vivo GSIS of HF-fed ACE2-deficient mice. These results demonstrate a critical role for endogenous ACE2 in the adaptive β-cell hyperinsulinemic response to HF feeding through regulation of β-cell proliferation and growth.
Collapse
Affiliation(s)
- Robin Shoemaker
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| | - Frederique Yiannikouris
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| | - Sean Thatcher
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| | - Lisa Cassis
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| |
Collapse
|
12
|
Liu R, Qi H, Wang J, Wang Y, Cui L, Wen Y, Yin C. Ulinastatin activates the renin-angiotensin system to ameliorate the pathophysiology of severe acute pancreatitis. J Gastroenterol Hepatol 2014; 29:1328-37. [PMID: 24628092 DOI: 10.1111/jgh.12584] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/28/2014] [Indexed: 01/13/2023]
Abstract
BACKGROUND AND AIM Ulinastatin is a drug used effectively to alleviate symptoms and improve the pathophysiology of various types of pancreatitis. However, the molecular mechanism responsible for its action remains unknown. Therefore, we further explore the therapeutic effects of ulinastatin and investigate possible molecular pathways modulated by this drug in the development of severe acute pancreatitis (SAP). METHODS SAP mouse model was created by administering intraperitoneal injections of cerulein and lipopolysaccharide. Pancreatic injury was assessed by performing biochemical and histological assays and by measuring the inflammatory response of the pancreas. Specifically, we examined changes in the expression of components of the rennin-angiotensin system (RAS), including angiotensin-converting enzyme (ACE)-angiotensin II (Ang II)-angiotensin type 1 receptor (AT-1R), and ACE2-Ang-(1-7)-Mas receptor. RESULTS When SAP mouse models were treated with ulinastatin at a dosage of 50,000 U/kg body weight, we found, through biochemical and histopathological analyses, that the pancreatic injury was significantly ameliorated. Administration of ulinastatin to SAP mice led to increased expression of ACE2, Ang-(1-7), and Mas receptor, decreased expression of serum Ang II and pancreatic AT-1R, and no alterations in the expression of pancreatic ACE and Ang II when compared to cerulein-treated control group that did not receive ulinastatin. CONCLUSIONS This study shows that ulinastatin has differential effects on the two axes of the RAS during SAP. Our results further suggest that upregulation of components of the ACE2-Ang-(1-7)-Mas pathway might be an important mechanism contributing to the therapeutic role of ulinastatin in alleviating pancreatitis-associated symptoms.
Collapse
Affiliation(s)
- Ruixia Liu
- Department of Infection, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | | | | | | | | | | | | |
Collapse
|
13
|
Shao C, Yu L, Gao L. Activation of angiotensin type 2 receptors partially ameliorates streptozotocin-induced diabetes in male rats by islet protection. Endocrinology 2014; 155:793-804. [PMID: 24302627 PMCID: PMC3929733 DOI: 10.1210/en.2013-1601] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have previously demonstrated that rat islets express a high density of angiotensin type 2 receptors and that activation of this receptor evokes insulinotropic effect. In this study, we evaluated the protective effects of Compound 21 (C21), a nonpeptide angiotensin type 2 receptor agonist, on islets in streptozotocin (STZ)-induced diabetes. Rats were assigned to five groups: normal, STZ, and STZ plus C21 (0.24, 0.48, and 0.96 mg/kg·d). C21 was continually infused by a sc implanted osmotic minipump for 14 days, and STZ was bolus injected on day 7. Body weight, water intake, urine excretion, and blood glucose were monitored daily. On the last day, the rats received an oral glucose tolerance test, and the pancreata were saved to examine islet morphology and biochemical parameters of oxidative stress and apoptosis. We found that, compared with control STZ rats, C21-treated STZ rats displayed less water intake and urine excretion, lower blood glucose, higher serum insulin concentration, and improved glucose tolerance. These rats had more islets, larger islet mass, and up-regulated insulin protein and proinsulin 2 mRNA expressions in the pancreas. Their islets displayed lower superoxide, decreased gp91 expression, and increased superoxide dismutase 1 expression as well as less apoptosis and down-regulated caspase-3 expression. In the epididymal adipose tissue of these rats, we found a decreased adipocyte size and up-regulated adipocyte protein 2 expression. The protective effects of C21 on β-cells against the toxic effects of STZ were also confirmed in cultured INS-1E cells. These data suggest that C21 ameliorates STZ-induced diabetes by protecting pancreatic islets via antioxidative and antiapoptotic effects.
Collapse
Affiliation(s)
- Chunhong Shao
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska 68198
| | | | | |
Collapse
|
14
|
Shao C, Zucker IH, Gao L. Angiotensin type 2 receptor in pancreatic islets of adult rats: a novel insulinotropic mediator. Am J Physiol Endocrinol Metab 2013; 305:E1281-91. [PMID: 24085035 PMCID: PMC3840212 DOI: 10.1152/ajpendo.00286.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In the present study, we evaluated the relative abundance of angiotensin type 2 receptor (AT2R) protein in various tissues of adult rats. We found that pancreatic islets expressed the highest AT2R protein compared with all other tissues. Accordingly, we then determined the functional significance of AT2R in the endocrine pancreas in in vivo and in vitro experiments by using angiotensin II (ANG II) alone, losartan (Los; AT1R antagonist), compound 21 (C21; AT2R agonist), and PD-123319 (PD; AT2R antagonist). Experiments carried out in rats indicated that, 1) ANG II treatment significantly increased plasma insulin concentration (1.51 ± 0.20 vs. 0.82 ± 0.14 ng/ml, n = 7, P < 0.05) in the fed state. This insulinotropic effect was further augmented by combined treatment with ANG II + Los (2.31 ± 0.25 ng/ml, n = 7, P < 0.01). C21 also elevated insulin levels (2.13 ± 0.20 ng/ml, n = 7, P < 0.01), which was completely abolished by PD. 2) ANG II impaired glucose tolerance, whereas ANG II + Los or C21 improved this function. 3) All treated rats displayed an enhanced insulin secretory response to a glucose challenge. 4) All treated rats displayed upregulated proinsulin 2 mRNA and insulin protein expression in the pancreas. In in vitro experiments using INS-1E cells and isolated rat islets, we found that AT2R activation significantly improved insulin biosynthesis and secretion. These results suggest that the AT2R functions as an insulinotropic mediator. AT2R and its downstream signaling pathways may be potential therapeutic targets for diabetes.
Collapse
Affiliation(s)
- Chunhong Shao
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | | | | |
Collapse
|
15
|
Abstract
The renin-angiotensin system (RAS) is known as a circulating or hormonal system regulating blood pressure, electrolyte and fluid homeostasis. Recent studies have found that, in addition to the circulating RAS, local renin-angiotensin systems also exist in several tissues and organs. Pancreatic renin-angiotensin system can not only regulate exocrine and endocrine function but also, via paracrine and (or) autocrine mechanisms, participate in the pathology and pathophysiology of pancreas-related diseases such as acute pancreatitis, diabetes, and pancreatic cancer. Acute pancreatitis (AP) is a common acute abdominal disease of the digestive system, which is often complicated with many other serious diseases and is therefore associated with a high overall mortality. At present, the etiology and pathogenesis of AP have not been fully elucidated yet. Thus, the proposed concept of a local RAS in the pancreas may provide a new avenue for the development of new treatments for AP.
Collapse
|
16
|
Madec AM, Cassel R, Dubois S, Ducreux S, Vial G, Chauvin MA, Mesnier A, Chikh K, Bosco D, Rieusset J, Van Coppenolle F, Thivolet C. Losartan, an angiotensin II type 1 receptor blocker, protects human islets from glucotoxicity through the phospholipase C pathway. FASEB J 2013; 27:5122-30. [PMID: 24008754 DOI: 10.1096/fj.13-234104] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
As shown in a large clinical prospective trial, inhibition of the renin-angiotensin system (RAS) can delay the onset of type 2 diabetes in high-risk individuals. We evaluated the beneficial effects of RAS inhibition on β-cell function under glucotoxic conditions. Human islets from 13 donors were cultured in 5.5 mM (controls) or 16.7 mM glucose [high glucose (HG)] for 4 d with or without losartan (5 μM), a selective AT1R blocker, and/or U73122 (2 μM), a selective PLC inhibitor, during the last 2 d. HG induced RAS activation with overexpression of AT1R (P<0.05) and angiotensinogen (P<0.001) mRNAs. HG increased endoplasmic reticulum (ER) stress markers (P<0.001) such as GRP78, sXBP1, and ATF4 mRNAs and Grp78 protein levels (P<0.01). HG also decreased reticular calcium concentration (P<0.0001) and modified protein expressions of ER calcium pumps with reduction of SERCA2b (P<0.01) and increase of IP3R2 (P<0.05). Losartan prevented these deleterious effects and was associated with improved insulin secretion despite HG exposure. AT1R activation triggers the PLC-IP3-calcium pathway. Losartan prevented the increase of PLC β1 and γ1 protein levels induced by HG (P<0.05). U73122 reproduced all the protective effects of losartan. AT1R blockade protects human islets from the deleterious effects of glucose through inhibition of the PLC-IP3-calcium pathway.
Collapse
Affiliation(s)
- Anne-Marie Madec
- 2INSERM U1060/University Lyon 1/Inra 1235, Lyon-Sud Medicine, Faculty, 165 Chemin du Grand Revoyet-BP 12, 69921 Oullins Cedex, France.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Amisten S, Salehi A, Rorsman P, Jones PM, Persaud SJ. An atlas and functional analysis of G-protein coupled receptors in human islets of Langerhans. Pharmacol Ther 2013; 139:359-91. [DOI: 10.1016/j.pharmthera.2013.05.004] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 05/03/2013] [Indexed: 12/17/2022]
|
18
|
Than A, Leow MKS, Chen P. Control of adipogenesis by the autocrine interplays between angiotensin 1-7/Mas receptor and angiotensin II/AT1 receptor signaling pathways. J Biol Chem 2013; 288:15520-31. [PMID: 23592774 DOI: 10.1074/jbc.m113.459792] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Angiotensin II (AngII), a peptide hormone released by adipocytes, can be catabolized by adipose angiotensin-converting enzyme 2 (ACE2) to form Ang(1-7). Co-expression of AngII receptors (AT1 and AT2) and Ang(1-7) receptors (Mas) in adipocytes implies the autocrine regulation of the local angiotensin system upon adipocyte functions, through yet unknown interactive mechanisms. In the present study, we reveal the adipogenic effects of Ang(1-7) through activation of Mas receptor and its subtle interplays with the antiadipogenic AngII-AT1 signaling pathways. Specifically, in human and 3T3-L1 preadipocytes, Ang(1-7)-Mas signaling promotes adipogenesis via activation of PI3K/Akt and inhibition of MAPK kinase/ERK pathways, and Ang(1-7)-Mas antagonizes the antiadipogenic effect of AngII-AT1 by inhibiting the AngII-AT1-triggered MAPK kinase/ERK pathway. The autocrine regulation of the AngII/AT1-ACE2-Ang(1-7)/Mas axis upon adipogenesis has also been revealed. This study suggests the importance of the local regulation of the delicately balanced angiotensin system upon adipogenesis and its potential as a novel therapeutic target for obesity and related metabolic disorders.
Collapse
Affiliation(s)
- Aung Than
- Division of Bioengineering, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457
| | | | | |
Collapse
|
19
|
van der Zijl NJ, Moors CCM, Goossens GH, Blaak EE, Diamant M. Does interference with the renin-angiotensin system protect against diabetes? Evidence and mechanisms. Diabetes Obes Metab 2012; 14:586-95. [PMID: 22226145 DOI: 10.1111/j.1463-1326.2012.01559.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Agents interfering with the renin-angiotensin system (RAS) were consistently shown to lower the incidence of type 2 diabetes mellitus (T2DM), as compared to other antihypertensive drugs, in hypertensive high-risk populations. The mechanisms underlying this protective effect of RAS blockade using angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers on glucose metabolism are not fully understood. In this article, we will review the evidence from randomized controlled trials and discuss the proposed mechanisms as to how RAS interference may delay the onset of T2DM. In particular, as T2DM is characterized by β-cell dysfunction and obesity-related insulin resistance, we address the mechanisms that underlie RAS blockade-induced improvement in β-cell function and insulin sensitivity.
Collapse
Affiliation(s)
- N J van der Zijl
- Diabetes Center, Department of Internal Medicine, VU University Medical Center, Amsterdam, The Netherlands.
| | | | | | | | | |
Collapse
|
20
|
Skipworth JRA, Szabadkai G, Olde Damink SWM, Leung PS, Humphries SE, Montgomery HE. Review article: pancreatic renin-angiotensin systems in health and disease. Aliment Pharmacol Ther 2011; 34:840-52. [PMID: 21851372 DOI: 10.1111/j.1365-2036.2011.04810.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND In addition to the circulating (endocrine) renin-angiotensin system (RAS), local renin-angiotensin systems are now known to exist in diverse cells and tissues. Amongst these, pancreatic renin-angiotensin systems have recently been identified and may play roles in the physiological regulation of pancreatic function, as well as being implicated in the pathogenesis of pancreatic diseases including diabetes, pancreatitis and pancreatic cancer. AIM To review and summarise current knowledge of pancreatic renin-angiotensin systems. METHODS We performed an extensive PubMed, Medline and online review of all relevant literature. RESULTS Pancreatic RAS appear to play various roles in the regulation of pancreatic physiology and pathophysiology. Ang II may play a role in the development of pancreatic ductal adenocarcinoma, via stimulation of angiogenesis and prevention of chemotherapy toxicity, as well as in the initiation and propagation of acute pancreatitis (AP); whereas, RAS antagonism is capable of preventing new-onset diabetes and improving glycaemic control in diabetic patients. Current evidence for the roles of pancreatic RAS is largely based upon cell and animal models, whilst definitive evidence from human studies remains lacking. CONCLUSIONS The therapeutic potential for RAS antagonism, using cheap and widely available agents, and may be untapped and such roles are worthy of active investigation in diverse pancreatic disease states.
Collapse
Affiliation(s)
- J R A Skipworth
- Department of Surgery and Interventional Science, UCL, London, UK.
| | | | | | | | | | | |
Collapse
|
21
|
Li C, Jones PM, Persaud SJ. Role of the endocannabinoid system in food intake, energy homeostasis and regulation of the endocrine pancreas. Pharmacol Ther 2011; 129:307-20. [DOI: 10.1016/j.pharmthera.2010.10.006] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Accepted: 10/13/2010] [Indexed: 01/26/2023]
|
22
|
Siebelmann M, Wensing J, Verspohl EJ. The impact of ANG II and IV on INS-1 cells and on blood glucose and plasma insulin. J Recept Signal Transduct Res 2010; 30:234-45. [PMID: 20524779 DOI: 10.3109/10799893.2010.487491] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The impact of angiotensin (ANG) for peripheral, global effects is well known. Local ANG systems including that of the insulin-releasing beta cell are not well investigated. In insulin-secreting cell line (INS-1), AT(1) and AT(4) receptors for ANG II and IV were demonstrated by Western blots. Only small amounts of ANG II-binding sites of low affinity were observed. ANG II and SARILE displaced binding of (125)I-ANG II. ANG II and IV as well as their non-degradable analogs SARILE and Nle-ANG IV increased the glucose-induced insulin release in a bell-shaped way; the maximum effect was at approximately 1 nM. The increase was antagonized by 1 microM losartan or 10 microM divalinal (AT(1) and AT(4) receptor antagonists, respectively). The insulin release was accompanied by a (45)Ca(2+) uptake in the case of ANG II and ANG IV. Divalinal abolished the effect of ANG IV and Nle-ANG IV on this parameter. ANG IV reduced the increase in blood glucose during a glucose tolerance test with corresponding, albeit smaller effects on plasma insulin. Using confocal laser scanning microscopy, transfected insulin-regulated aminopeptidase (IRAP) with AT(4) receptors was shown to be accumulated close to the nucleus and the cytosolic membrane, whereas GLUT4 was not detectable. IRAP was inhibited by ANG IV. In conclusion, AT(1) and AT(4) receptors may be involved in diabetic homeostasis. Effects are mediated by insulin release, which is accompanied by an influx of extracellular Ca(2+). The impact of ANG IV/IRAP agonists may be worth being used as antidiabetics.
Collapse
Affiliation(s)
- M Siebelmann
- Department of Pharmacology, Institute of Medicinal Chemistry, University of Muenster, Münster, Germany
| | | | | |
Collapse
|
23
|
Moritz KM, Cuffe JSM, Wilson LB, Dickinson H, Wlodek ME, Simmons DG, Denton KM. Review: Sex specific programming: a critical role for the renal renin-angiotensin system. Placenta 2010; 31 Suppl:S40-6. [PMID: 20116093 DOI: 10.1016/j.placenta.2010.01.006] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 01/06/2010] [Accepted: 01/06/2010] [Indexed: 12/21/2022]
Abstract
The "Developmental Origins of Health and Disease" hypothesis has caused resurgence of interest in understanding the factors regulating fetal development. A multitude of prenatal perturbations may contribute to the onset of diseases in adulthood including cardiovascular and renal diseases. Using animal models such as maternal glucocorticoid exposure, maternal calorie or protein restriction and uteroplacental insufficiency, studies have identified alterations in kidney development as being a common feature. The formation of a low nephron endowment may result in impaired renal function and in turn may contribute to disease. An interesting feature in many animal models of developmental programming is the disparity between males and females in the timing of onset and severity of disease outcomes. The same prenatal insult does not always affect males and females in the same way or to the same degree. Recently, our studies have focused on changes induced in the kidney of both the fetus and the offspring, following a perturbation during pregnancy. We have shown that changes in the renin-angiotensin system (RAS) occur in the kidney. The changes are often sex specific which may in part explain the observed sex differences in disease outcomes and severity. This review explores the evidence suggesting a critical role for the RAS in sex specific developmental programming of disease with particular reference to the immediate and long term changes in the local RAS within the kidney.
Collapse
Affiliation(s)
- K M Moritz
- School of Biomedical Sciences, The University of Queensland, St Lucia 4072, Australia.
| | | | | | | | | | | | | |
Collapse
|
24
|
Chu KY, Cheng Q, Chen C, Au LS, Seto SW, Tuo Y, Motin L, Kwan YW, Leung PS. Angiotensin II exerts glucose-dependent effects on Kv currents in mouse pancreatic beta-cells via angiotensin II type 2 receptors. Am J Physiol Cell Physiol 2009; 298:C313-23. [PMID: 19889960 DOI: 10.1152/ajpcell.00575.2008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hyperglycemia-associated glucotoxicity induces beta-cell apoptosis but the underlying mechanisms are unknown. Interestingly, prolonged exposure to high glucose upregulates the expression and function of the renin-angiotensin system (RAS). We hypothesize that the voltage-gated outward potassium (K(v)) current, which governs beta-cell membrane potential and insulin secretion, has a role in glucotoxicity. In this study, we investigated the effects of prolonged exposure to high glucose on mouse pancreatic beta-cells and concurrent effects on the RAS by examining changes in expression of angiotensin II (ANG II) receptors and changes in the expression and activity of K(v) channels. beta-Cells were incubated in high glucose medium for 1-7 days and then were examined with electrophysiological and molecular biology techniques. Prolonged exposure to high glucose produced a marked increase in beta-cell primary K(v) channel subunit, K(v)2.1, expression and K(v) current amplitude. Enhanced expression of ANG II type 1 receptor (AT(1)R) was also observed under high glucose conditions, whereas blockade of AT(1)R by losartan did not alter K(v) channel expression. External application of ANG II reduced K(v) current amplitude under normal, but not high, glucose conditions. The effect of ANG II on K(v) channel gating was abolished by ANG II type 2 receptor (AT(2)R) antagonism. These data suggest that hyperglycemia alters beta-cell function through modification of the K(v) channel which may be associated with the RAS.
Collapse
Affiliation(s)
- Kwan Yi Chu
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
| | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Abstract
Studies of gene expression by different islet endocrine cell populations can provide useful information about signal transduction cascades regulating alpha-, beta- and delta-cell function. Experiments on expression of beta-cell gene products are relatively easy to perform in rodent islets as these islets are readily isolated at high purities from the exocrine pancreas; beta-cells are the majority cell type and their autofluorescent properties allow them to be purified from non-beta-cells by fluorescence-activated cell sorting (FACS). However, the situation is rather more complicated when investigating human islet gene expression profiles as purities of collagenase-isolated human islets are generally less than those of mouse and rat islets; beta-cells are less abundant in human islets than they are in rodent islets and conventional FACS purification of human islet beta-cells is not possible because of their high background fluorescence. In addition, FACS does not provide pure alpha- or delta-cell populations from either rodent or human islets. We have developed single-cell RT-PCR protocols to allow identification of genes expressed by human islet alpha-, beta- and delta-cells. This chapter describes these protocols and appropriate steps that should be followed to minimise generation of false-positive amplicons.
Collapse
|
26
|
Angiotensin receptor blockers in the treatment of NASH/NAFLD: could they be a first-class option? Adv Ther 2008; 25:1141-74. [PMID: 18972077 DOI: 10.1007/s12325-008-0110-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a condition pathogenically linked to metabolic syndrome (MS) by insulin resistance (IR), and characterized by hepatic steatosis in the absence of significant alcohol use, hepatotoxicity, and/or other known liver diseases.The principles of NAFLD therapy target IR: the key point of MS. As the renin-angiotensin system (RAS) plays a central role in IR, and subsequently in NAFLD and nonalcoholic steatohepatitis (NASH), an attempt to block the deleterious effects of RAS overexpression seems a logical target. While many potential therapies tested in NASH target only the consequences of this condition, or try to "get rid" of excessive fat, angiotensin receptor blockers (ARBs) could act as an elegant tool for adequate correction of the various imbalances that act in harmony in NASH/NAFLD. Indeed, by inhibiting RAS we can improve the intracellular insulin signaling pathway, better control adipose tissue proliferation and adipokine production, and produce more balanced local and systemic levels of various cytokines. At the same time, by controlling the local RAS in the liver we might be able to prevent at least fibrosis and also slow down the vicious cycle that links steatosis to necroinflammation. By targeting the pancreatic effects of angiotensin we should be able to preserve an adequate insulin secretion and acquire a better metabolic balance.In our opinion there are two major advantages of ARBs that make them a possible therapeutic option for treating NASH and MS: their specific antihypertensive effect, and their impact on liver fibrosis. In light of this, and based on the current evidence (including existent human studies), we can speculate that some ARBs like telmisartan, candesartan, and losartan can be beneficial in treating NASH/NAFLD and its consequences, and further larger controlled clinical trials will bring consistent data into this field.
Collapse
|
27
|
Abstract
New components and functions of the renin-angiotensin system (RAS) are still being unravelled. The classical RAS as it looked in the middle 1970s consisted of circulating renin, acting on angiotensinogen to produce angiotensin I, which in turn was converted into angiotensin II (Ang II) by angiotensin-converting enzyme (ACE). Ang II, still considered the main effector of RAS was believed to act only as a circulating hormone via angiotensin receptors, AT1 and AT2. Since then, an expanded view of RAS has gradually emerged. Local tissue RAS systems have been identified in most organs. Recently, evidence for an intracellular RAS has been reported. The new expanded view of RAS therefore covers both endocrine, paracrine and intracrine functions. Other peptides of RAS have been shown to have biological actions; angiotensin 2-8 heptapeptide (Ang III) has actions similar to those of Ang II. Further, the angiotensin 3-8 hexapeptide (Ang IV) exerts its actions via insulin-regulated amino peptidase receptors. Finally, angiotensin 1-7 (Ang 1-7) acts via mas receptors. The discovery of another ACE2 was an important complement to this picture. The recent discovery of renin receptors has made our view of RAS unexpectedly complex and multilayered. The importance of RAS in cardiovascular disease has been demonstrated by the clinical benefits of ACE inhibitors and AT1 receptor blockers. Great expectations are now generated by the introduction of renin inhibitors. Indeed, RAS regulates much more and diverse physiological functions than previously believed.
Collapse
Affiliation(s)
- F Fyhrquist
- Minerva Institute for Medical Research and Department of Internal Medicine, Helsinki University Central Hospital, Helsinki, Finland.
| | | |
Collapse
|
28
|
O'Carroll AM, Howell GM, Roberts EM, Lolait SJ. Vasopressin potentiates corticotropin-releasing hormone-induced insulin release from mouse pancreatic beta-cells. J Endocrinol 2008; 197:231-9. [PMID: 18434353 PMCID: PMC2386661 DOI: 10.1677/joe-07-0645] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Arginine vasopressin (AVP) and corticotropin-releasing hormone (CRH) have both been implicated in modulating insulin secretion from pancreatic beta-cells. In the present study, we investigated the insulin-secreting activities of AVP and CRH in wild-type and AVP VIb receptor knockout mice. Both neuropeptides stimulated insulin secretion from isolated mouse pancreatic islets. The response of islets to CRH was increased fourfold by concomitant incubation with a subthreshold dose of AVP that alone did not stimulate insulin secretion. Activation of the endogenously expressed M3 receptor by the cholinergic agonist carbachol also potentiated CRH-induced insulin secretion, indicating that the phenomenon may be pathway specific (i.e. Ca2+-phospholipase C) rather than agonist specific. The protein kinase C (PKC) inhibitors Ro-31-8425 and bisindolylmaleimide I attenuated the potentiating effect of AVP on CRH-stimulated insulin secretion and blocked AVP-stimulated insulin secretion. A possible interaction between the PKC and protein kinase A pathways was also investigated. The phorbol ester phorbol myristate acetate (PMA) stimulated insulin secretion, while the addition of both PMA and CRH enhanced insulin secretion over that measured with either PMA or CRH alone. Additionally, no AVP potentiation of CRH-stimulated insulin secretion was observed upon incubation in Ca2+-free Krebs-Ringer buffer. Taken together, the present study suggests a possible synergism between AVP and CRH to release insulin from pancreatic beta-cells that relies at least in part on activation of the PKC signaling pathway and is dependent on extracellular Ca2+. This is the first example of a possible interplay between the AVP and CRH systems outside of the hypothalamic-pituitary-adrenal axis.
Collapse
Affiliation(s)
- Anne-Marie O'Carroll
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology (LINE), University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol BS1 3NY, UK.
| | | | | | | |
Collapse
|
29
|
Ramracheya RD, Muller DS, Squires PE, Brereton H, Sugden D, Huang GC, Amiel SA, Jones PM, Persaud SJ. Function and expression of melatonin receptors on human pancreatic islets. J Pineal Res 2008; 44:273-9. [PMID: 18194202 DOI: 10.1111/j.1600-079x.2007.00523.x] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Melatonin is known to inhibit insulin secretion from rodent beta-cells through interactions with cell-surface MT1 and/or MT2 receptors, but the function of this hormone in human islets of Langerhans is not known. In the current study, melatonin receptor expression by human islets was examined by reverse transcription-polymerase chain reaction (RT-PCR) and the effects of exogenous melatonin on intracellular calcium ([Ca2+]i) levels and islet hormone secretion were determined by single cell microfluorimetry and radioimmunoassay, respectively. RT-PCR amplifications indicated that human islets express mRNAs coding for MT1 and MT2 melatonin receptors, although MT2 mRNA expression was very low. Analysis of MT1 receptor mRNA expression at the single cell level indicated that it was expressed by human islet alpha-cells, but not by beta-cells. Exogenous melatonin stimulated increases in intracellular calcium ([Ca2+]i) in dissociated human islet cells, and stimulated glucagon secretion from perifused human islets. It also stimulated insulin secretion and this was most probably a consequence of glucagon acting in a paracrine fashion to stimulate beta-cells as the MT1 receptor was absent in beta-cells. Melatonin did not decrease 3', 5'-cyclic adenosine monophosphate (cyclic AMP) levels in human islets, but it inhibited cyclic AMP in the mouse insulinoma (MIN6) beta-cell line and it also inhibited glucose-stimulated insulin secretion from MIN6 cells. These data suggest that melatonin has direct stimulatory effects at human islet alpha-cells and that it stimulates insulin secretion as a consequence of elevated glucagon release. This study also indicates that the effects of melatonin are species-specific with primarily an inhibitory role in rodent beta-cells and a stimulatory effect in human islets.
Collapse
Affiliation(s)
- Reshma D Ramracheya
- Beta Cell Development & Function Group, School of Biomedical & Health Sciences, King's College London, London, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Chu KY, Leung PS. Angiotensin II Type 1 receptor antagonism mediates uncoupling protein 2-driven oxidative stress and ameliorates pancreatic islet beta-cell function in young Type 2 diabetic mice. Antioxid Redox Signal 2007; 9:869-78. [PMID: 17508912 DOI: 10.1089/ars.2007.1590] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We recently identified a local pancreatic islet renin-angiotensin system (RAS), and demonstrated that it is upregulated in an animal model of obesity-induced type 2 diabetes mellitus (T2DM). Moreover, angiotensin II type 1 receptor (AT1R) antagonism improves beta-cell function and glucose tolerance in young T2DM mice and delays the onset of diabetes. Meanwhile, obesity-induced T2DM results in oxidative stress-mediated activation of uncoupling protein 2 (UCP2), a negative regulator of islet function. In the present study, we postulated that some of the protective effects of AT1R antagonism might be mediated through interference with this pathway and tested this hypothesis in a T2DM animal model. Losartan, an AT1R antagonist, was given to 4-week-old obese db/db mice for a period of 8 weeks. UCP2-driven oxidative damage and apoptosis were then analyzed in isolated islets. Losartan selectively inhibited oxidative stress via downregulation of NADPH oxidase; this in turn suppressed UCP2 expression, thus improving beta-cell insulin secretion and decreasing apoptosis-induced beta-cell mass loss in db/db mouse islets. These data indicate that islet AT1R activation in young diabetic mice can generate progressive islet beta-cell failure through UCP-driven oxidative damage.
Collapse
Affiliation(s)
- Kwan Yi Chu
- Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | | |
Collapse
|
31
|
Chipitsyna G, Gong Q, Gray CF, Haroon Y, Kamer E, Arafat HA. Induction of monocyte chemoattractant protein-1 expression by angiotensin II in the pancreatic islets and beta-cells. Endocrinology 2007; 148:2198-208. [PMID: 17303665 DOI: 10.1210/en.2006-1358] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Angiotensin II (AngII), the principal hormone of the renin-angiotensin system, is actively generated in the pancreas and has been suggested as a key mediator of inflammation. Monocyte chemoattractant protein-1 (MCP-1) is a chemokine that plays an important role in the recruitment of mononuclear cells into the pancreatic islets. In this study, we investigated the potential molecular basis for the role of AngII in islet inflammation through studying its effect on MCP-1. AngII significantly increased the expression of MCP-1 mRNA and protein in the RINm5F beta-cell line and activated MCP-1 promoter. AngII-MCP-1 mRNA induction was inhibited by an AngII type 1 receptor antagonist but was unchanged by an AngII type 2 receptor antagonist. AngII-MCP-1 induction was inhibited by the tyrosine kinase inhibitor genistein, suggesting a MAPK signaling mechanism. AngII activated the phosphorylation of ERK1/2 but not p38 or c-Jun NH(2)-terminal MAPKs. Inhibition of ERK1/2 activation reduced the AngII-induced MCP-1 synthesis. In nonobese diabetic mice pancreata, the temporal pattern of angiotensin-converting enzyme expression correlated well with progression of insulitis and beta-cell destruction. Immunostaining of pancreatic serial sections show colocalization of angiotensin-converting enzyme with MCP-1 in beta-cells in the islets. In freshly isolated islets from normoglycemic mice, AngII alone and in combination with IL-1beta elicited an inflammatory response by stimulation of MCP-1. Our data suggest a positive autocrine/paracrine action for the local pancreatic AngII-generating system during insulitis and provide the first insight into an AngII-initiated signal transduction pathway that regulates MCP-1 as a possible inflammatory mechanism in the islets.
Collapse
Affiliation(s)
- Galina Chipitsyna
- Department of Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | | | | | | | | | | |
Collapse
|
32
|
Ernsberger P, Koletsky RJ. Metabolic actions of angiotensin receptor antagonists: PPAR-gamma agonist actions or a class effect? Curr Opin Pharmacol 2007; 7:140-5. [PMID: 17303473 PMCID: PMC2930911 DOI: 10.1016/j.coph.2006.11.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Accepted: 11/03/2006] [Indexed: 10/23/2022]
Abstract
Accumulating basic and clinical data support the hypothesis that angiotensin receptor blockers have beneficial effects on glucose and lipid metabolism that are not shared by other classes of antihypertensive agents. These metabolic actions might only partially be shared by angiotensin-converting enzyme inhibitors. Specific benefits beyond those of other angiotensin receptor blockers have been claimed for telemesartan and, to a lesser extent, irbesartan based on a partial agonist action on PPAR-gamma receptors. Although the evidence is strong in vitro, specific actions not shared by other angiotensin receptor blockers have not yet been convincingly demonstrated in vivo or in clinical trials. In many cases, a full range of doses has not been compared, and the apparent superiority of telmesartan could be an artifact of its higher receptor binding affinity, greater tissue penetration owing to lipophilicity, and longer half life.
Collapse
Affiliation(s)
- Paul Ernsberger
- Department of Nutrition, Case Western Reserve University, School of Medicine, Cleveland, OH 44106-4906, USA.
| | | |
Collapse
|
33
|
Leung PS. Mechanisms of protective effects induced by blockade of the renin-angiotensin system: novel role of the pancreatic islet angiotensin-generating system in Type 2 diabetes. Diabet Med 2007; 24:110-6. [PMID: 17257271 DOI: 10.1111/j.1464-5491.2007.02072.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Large clinical trials have shown that inhibition of the renin-angiotensin system (RAS) can delay and/or prevent the onset of Type 2 diabetes mellitus (T2DM) in high-risk individuals, such as those with hypertension or chronic heart failure. Moreover, a meta-analysis of these randomized clinical studies concluded that the mean weighted relative risk of development of T2DM was reduced by 25% in those patients treated with angiotensin II receptor blockers or angiotensin-converting enzyme inhibitors. In spite of these firm clinical data, the mechanistic pathways mediating the protective activity of RAS blockade have yet to be resolved. Of particular interest is the recently identified local pancreatic RAS and, perhaps more importantly, the finding that it is up-regulated in animal models of T2DM. This putative local RAS may regulate pancreatic islet blood flow, oxygen tension, and islet (pro)insulin biosynthesis. It might also mediate the generation of reactive oxygen species, thereby causing oxidative stress-induced pancreatic beta-cell apoptosis and fibrosis. Moreover, findings that RAS blockade improved beta-cell secretory function and cell mass in experimental animal models of Type 2 diabetes indicate that inhibition of RAS activation may play a pivotal role in protecting islet cell function, and furthermore may prevent the development of overt T2DM. Such data supporting the involvement of the local pancreatic RAS in islet function, as well as a causal relationship between RAS activation and T2DM, and RAS induced beta-cell dysfunction, mandate further investigation into the role of RAS in the pathogenesis of the progressive islet impairment observed in patients with T2DM.
Collapse
Affiliation(s)
- P S Leung
- Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong.
| |
Collapse
|
34
|
Abstract
The systemic renin-angiotensin system (RAS) plays an important role in regulating blood pressure, electrolyte and fluid homeostasis. However, local RASs also exist in diverse tissues and organs, where they play a multitude of autocrine, paracrine and intracrine physiological roles. The existence of a local RAS is now recognized in pancreatic acinar, islet, duct, endothelial and stellate cells, the expression of which is modulated in response to physiological and pathophysiological stimuli such as hypoxia, pancreatitis, islet transplantation, hyperglycaemia, and diabetes mellitus. This pancreatic RAS has been proposed to have important endocrine and exocrine roles in the pancreas, regulating local blood flow, duct cell sodium bicarbonate secretion, acinar cell digestive enzyme secretion, islet beta-cell (pro)insulin biosynthesis, and thus, glucose-stimulated insulin release, delta-cell somatostatin secretion, and pancreatic cell proliferation and differentiation. It may further mediate oxidative stress-induced cell inflammation, apoptosis and fibrosis. Further exploration of this system would probably offer new insights into the pathogenesis of pancreatitis, diabetes, cystic fibrosis and pancreatic cancer formation. New therapeutic targets and strategies might thus be suggested.
Collapse
Affiliation(s)
- Po Sing Leung
- Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
| |
Collapse
|
35
|
Persaud SJ, Muller D, Belin VD, Kitsou-Mylona I, Asare-Anane H, Papadimitriou A, Burns CJ, Huang GC, Amiel SA, Jones PM. The role of arachidonic acid and its metabolites in insulin secretion from human islets of langerhans. Diabetes 2007; 56:197-203. [PMID: 17192482 DOI: 10.2337/db06-0490] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The roles played by arachidonic acid and its cyclooxygenase (COX)-generated and lipoxygenase (LOX)-generated metabolites have been studied using rodent islets and insulin-secreting cell lines, but very little is known about COX and LOX isoform expression and the effects of modulation of arachidonic acid generation and metabolism in human islets. We have used RT-PCR to identify mRNAs for cytosolic phospholipase A(2) (cPLA(2)), COX-1, COX-2, 5-LOX, and 12-LOX in isolated human islets. COX-3 and 15-LOX were not expressed by human islets. Perifusion experiments with human islets indicated that PLA(2) inhibition inhibited glucose-stimulated insulin secretion, whereas inhibitors of COX-2 and 12-LOX enzymes enhanced basal insulin secretion and also secretory responses induced by 20 mmol/l glucose or by 50 mumol/l arachidonic acid. Inhibition of COX-1 with 100 mumol/l acetaminophen did not significantly affect glucose-stimulated insulin secretion. These data indicate that the stimulation of insulin secretion from human islets in response to arachidonic acid does not require its metabolism through COX-2 and 5-/12-LOX pathways. The products of COX-2 and LOX activities have been implicated in cytokine-mediated damage of beta-cells, so selective inhibitors of these enzymes would be expected to have a dual protective role in diabetes: they would minimize beta-cell dysfunction while maintaining insulin secretion through enhancing endogenous arachidonic acid levels.
Collapse
Affiliation(s)
- Shanta J Persaud
- Beta Cell Development and Function Group, Division of Reproductive Health, Endocrinology, and Development, King's College London, UK.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Muller D, Huang GC, Amiel S, Jones PM, Persaud SJ. Identification of insulin signaling elements in human beta-cells: autocrine regulation of insulin gene expression. Diabetes 2006; 55:2835-42. [PMID: 17003350 DOI: 10.2337/db06-0532] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Although many studies using rodent islets and insulinoma cell lines have been performed to determine the role of insulin in the regulation of islet function, the autocrine effect of insulin on insulin gene expression is still controversial, and no consensus has yet been achieved. Because very little is known about the insulin signaling pathway in human islets, we used single-cell RT-PCR to profile the expression of genes potentially involved in the insulin signaling cascade in human beta-cells. The detection of mRNAs for insulin receptor (IR)A and IRB; insulin receptor substrate (IRS)-1 and IRS-2; phosphoinositide 3-kinase (PI3K) catalytic subunits p110alpha, p110beta, PI3KC2alpha, and PI3KC2gamma; phosphoinositide-dependent protein kinase-1; protein kinase B (PKB)alpha, PKBbeta, and PKBgamma in the beta-cell population suggests the presence of a functional insulin signaling cascade in human beta-cells. Small interfering RNA-induced reductions in IR expression in human islets completely suppressed glucose-stimulated insulin gene expression, suggesting that insulin regulates its own gene expression in human beta-cells. Defects in this regulation may accentuate the metabolic dysfunction associated with type 2 diabetes.
Collapse
Affiliation(s)
- Dany Muller
- Beta Cell Development & Function Group, Division of Reproduction and Endocrinology, School of Biomedical and Health Sciences, King's College London, London SE1 1UL, UK.
| | | | | | | | | |
Collapse
|
37
|
Ernsberger P, Koletsky RJ. Metabolic effects of antihypertensive agents: role of sympathoadrenal and renin-angiotensin systems. Naunyn Schmiedebergs Arch Pharmacol 2006; 373:245-58. [PMID: 16783586 DOI: 10.1007/s00210-006-0080-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Accepted: 05/09/2006] [Indexed: 01/01/2023]
Abstract
Reports of beneficial, neutral and adverse impacts of antihypertensive drug classes on glucose and lipid metabolism can be found in human data. Furthermore, mechanisms for these diverse effects are often speculative and controversial. Clinical trial data on the metabolic effects of antihypertensive agents are highly contradictory. Comparisons of clinical trials involving different agents are complicated by differences in the spectrum of metabolic disturbances that accompany hypertension in different groups of patients. Two physiological systems are predominant at the interface between metabolic and cardiovascular regulation: the sympathetic nervous system (SNS) and the renin-angiotensin system (RAS). These two systems are major targets of antihypertensive drug actions, and also mediate many of the beneficial and adverse effects of antihypertensive agents on glucose and lipid metabolism. Thiazides and beta-adrenergic antagonists can adversely affect glucose and lipid metabolism, which are frequently compromised in human essential hypertension, and increase the incidence of new cases of diabetes. Laboratory studies confirm these effects, and suggest that compensatory activation of the SNS and RAS may be one mechanism. Other antihypertensives directly targeting the SNS and RAS may have beneficial effects on glucose and lipid metabolism, and may prevent diabetes. Resolution of the controversies surrounding the metabolic effects of antihypertensive agents can only be resolved by further laboratory studies, in addition to controlled clinical trials.
Collapse
|
38
|
Leung PS, de Gasparo M. Involvement of the Pancreatic Renin-Angiotensin System in Insulin Resistance and the Metabolic Syndrome. ACTA ACUST UNITED AC 2006; 1:197-203. [PMID: 17679833 DOI: 10.1111/j.1559-4564.2006.05460.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The cardiometabolic syndrome consists of several major components: hypertension, hyperinsulinemia, hyperlipidemia, and hyperglycemia. Central to this syndrome are insulin resistance and generation of reactive oxygen species; these features are particularly prominent in patients with type 2 diabetes mellitus. In this context, large clinical trials have shown that blockade of the renin-angiotensin system (RAS) is protective against type 2 diabetes. In spite of these solid clinical data, the mechanistic pathways by which RAS blockade achieves these protective effects have yet to be resolved. A recently identified local pancreatic islet RAS has, however, been implicated in this regard. Furthermore, RAS blockade was recently shown to enhance islet blood flow, oxygen tension, and insulin biosynthesis, thus improving beta-cell function and glucose tolerance. Meanwhile, RAS activation may also influence islet cell inflammatory responses, apoptosis, fibrosis, and superoxide anion production. This RAS-associated oxidative stress can induce islet cell dysfunction in the pancreas and insulin resistance in peripheral tissues.
Collapse
Affiliation(s)
- Po Sing Leung
- Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
| | | |
Collapse
|