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Chilton R, Wyatt J, Nandish S, Oliveros R, Lujan M. Cardiovascular comorbidities of type 2 diabetes mellitus: defining the potential of glucagonlike peptide-1-based therapies. Am J Med 2011; 124:S35-53. [PMID: 21194579 DOI: 10.1016/j.amjmed.2010.11.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The global epidemic of diabetes mellitus (~95% type 2 diabetes) has been fueled by a parallel increase in obesity and overweight. Together, these metabolic disease epidemics have contributed to the increasing incidence and prevalence of cardiovascular disease. The accumulation of metabolic and cardiovascular risk factors in patients with type 2 diabetes--risk factors that may exacerbate one another--complicates treatment. Inadequate treatment, treatment that fails to achieve goals, increases the risk for cardiovascular morbidity and mortality. From a clinical perspective, type 2 diabetes is a cardiovascular disease, an observation that is supported by a range of epidemiologic, postmortem, and cardiovascular imaging studies. Vascular wall dysfunction, and particularly endothelial dysfunction, has been posited as a "common soil" linking dysglycemic and cardiovascular diseases. Vascular wall dysfunction promoted by environmental triggers (e.g., sedentary lifestyle) and metabolic triggers (chronic hyperglycemia, obesity) has been associated with the upregulation of reactive oxygen species and chronic inflammatory and hypercoagulable states, and as such with the pathogenesis of type 2 diabetes, atherosclerosis, and cardiovascular disease. Glucagon-like peptide-1 (GLP)-1, an incretin hormone, and synthetic GLP-1 receptor agonists represent promising new areas of research and therapeutics in the struggle not only against type 2 diabetes but also against the cardiovascular morbidity and mortality associated with type 2 diabetes. In a number of small trials in humans, as well as in preclinical and in vitro studies, both native GLP-1 and GLP-1 receptor agonists have demonstrated positive effects on a range of cardiovascular disease pathologies and clinical targets, including such markers of vascular inflammation as high-sensitivity C-reactive protein, plasminogen activator inhibitor-1, and brain natriuretic peptide. Reductions in markers of dyslipidemia such as elevated levels of triglycerides and free fatty acids have also been observed, as have cardioprotective functions. Larger trials of longer duration will be required to confirm preliminary findings. In large human trials, GLP-1 receptor agonists have been associated with significant reductions in both blood pressure and weight.
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Affiliation(s)
- Robert Chilton
- Catheterization Laboratory, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA.
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402
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Dharmalingam M, Sriram U, Baruah MP. Liraglutide: A review of its therapeutic use as a once daily GLP-1 analog for the management of type 2 diabetes mellitus. Indian J Endocrinol Metab 2011; 15:9-17. [PMID: 21584160 PMCID: PMC3079863 DOI: 10.4103/2230-8210.77571] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) is a progressive disease associated with significant morbidity and mortality. Even though progress have been accomplished in the management of type 2 diabetes, current treatment preferences for patients with this disease still fall short to address disease progression. With the present therapy, glycaemic control remains suboptimal and are often associated with weight gain and hypoglycaemia. Glucagon like peptide-1 (GLP-1) is an incretin hormone secreted from the small intestine that lowers fasting and postprandial glucose through multiple mechanisms including glucose-dependent insulin secretion, reduction of glucagon secretion, delaying gastric emptying and increased satiety. Liraglutide, a human glucagon-like peptide 1 (GLP-1) analogue is a treatment for T2DM that is administered as a once-daily subcutaneous injection. The efficacy and tolerability of liraglutide at doses of 0.6, 1.2, and 1.8 mg for T2DM, in combination with, and compared with, other T2DM treatments were investigated in the Liraglutide Effect and Action in Diabetes (LEAD) Phase III clinical trial program. In the LEAD trial, treatment with liraglutide was associated with substantial improvements in glycaemic control and low risk of hypoglycaemia. In addition liraglutide significantly improved β-cell function, reduced systolic blood pressure (BP) and induced weight loss. Overall, liraglutide was well tolerated. Recent data on safety and efficacy of liraglutide from real-life clinical practice settings also reiterate the better therapeutic profile of this molecule. Based on results from the LEAD programme, and real-life clinical experience, liraglutide has been demonstrated as an effective therapeutic intervention even at the early stage of diabetes regardless of with what, it has been used.
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Affiliation(s)
- Mala Dharmalingam
- Department of Endocrinology and Metabolism, M S Ramaiah Medical College, Bangalore, India
| | - Usha Sriram
- Clinical Endocrinology Education and Research (ACEER), Chennai, India
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403
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Giorgino F, Leonardini A, Natalicchio A, Laviola L. Multifactorial intervention in Type 2 diabetes: the promise of incretin-based therapies. J Endocrinol Invest 2011; 34:69-77. [PMID: 21233599 DOI: 10.1007/bf03346698] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Type 2 diabetes mellitus is increasing in prevalence at alarming rates. Concurrent with its expanding prevalence is the increase in the related risk of morbidity and mortality. Because diabetic patients are prone to cardiovascular disease, treatment strategies should address the cardiovascular risk factors, including blood pressure, lipids, and body weight, in addition to the glycemic aspects of the disease. Newer agents, such as glucagon-like peptide-1 (GLP-1) analogs and dipeptidyl peptidase-4 (DPP-4) inhibitors, have varying degrees of evidence to support their effects on body weight, blood pressure, and lipid levels, beyond glycated hemoglobin reduction. While GLP-1 agonists produce a weight loss, the DPP-4 inhibitors, conversely, appear to have a weight-neutral effect. Substantial evidence demonstrates that both medications produce modest reductions in systolic blood pressure and, in some cases, diastolic blood pressure, and reduce several markers of cardiovascular risk, including C-reactive protein. Moreover, GLP-1 influences endothelial function. The effect of the incretin hormones on serum lipids are either neutral or beneficial, with small, non-significant decreases in LDL cholesterol, increases in HDL cholesterol, and occasionally significant decreases in fasting triglyceride levels. Also, they have positive effects on hepatic steatosis. Although GLP-1 agonists and DPP-4 inhibitors are at present not appropriate for primary treatment of cardiovascular risks factors, the reduction of these parameters is evidently beneficial.
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Affiliation(s)
- F Giorgino
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, I- 70124 Bari, Italy.
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404
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Nauck MA. Incretin-based therapies for type 2 diabetes mellitus: properties, functions, and clinical implications. Am J Med 2011; 124:S3-18. [PMID: 21194578 DOI: 10.1016/j.amjmed.2010.11.002] [Citation(s) in RCA: 218] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagonlike peptide-1 (GLP-1), which are secreted by cells of the gastrointestinal tract in response to meal ingestion, exercise important glucoregulatory effects, including the glucose-dependent potentiation of insulin secretion by pancreatic β-cells. Research on the defective incretin action in type 2 diabetes mellitus suggests that the observed loss of insulinotropic activity may be due primarily to a decreased responsiveness of β-cells to GIP. GLP-1 does retain efficacy, albeit not at physiologic levels. Accordingly, augmentation of GLP-1 is a logical therapeutic strategy to ameliorate this deficiency, although the short metabolic half-life of the native hormone renders direct infusion impractical. GLP-1 receptor agonists that resist degradation by the enzyme dipeptidyl peptidase-4 (DPP-4) and have protracted-action kinetics have been developed, and DPP-4 inhibitors that slow the enzymatic cleavage of native GLP-1 provide alternative approaches to enhancing incretin-mediated glucose control. However, GLP-1 receptor agonists and DPP-4 inhibitors are premised on highly divergent mechanisms of action. DPP-4 is ubiquitously expressed in many tissues and is involved in a wide range of physiologic processes in addition to its physiologic influence on incretin hormone biological activity. GLP-1 receptor agonists provide a pharmacologic level of GLP-1 receptor stimulation, whereas DPP-4 inhibitors appear to increase levels of circulating GLP-1 to within the physiologic range. This article examines the physiology of the incretin system, mechanistic differences between GLP-1 receptor agonists and DPP-4 inhibitors used as glucose-lowering agents in the treatment of type 2 diabetes, and the implications of these differences for treatment. The results of recent head-to-head trials are reviewed, comparing the effects of incretin-based therapies on a range of clinical parameters, including glycemia, β-cell function, weight, and cardiovascular function.
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Affiliation(s)
- Michael A Nauck
- Bad Lauterberg Diabetes Center, Bad Lauterberg im Harz, Germany.
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405
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Abstract
There is emerging evidence to show that high levels of NEFA contribute to endothelial dysfunction and impaired insulin sensitivity. However, the impact of NEFA composition remains unclear. A total of ten healthy men consumed test drinks containing 50 g of palm stearin (rich in SFA) or high-oleic sunflower oil (rich in MUFA) on separate occasions; a third day included no fat as a control. The fats were emulsified into chocolate drinks and given as a bolus (approximately 10 g fat) at baseline followed by smaller amounts (approximately 3 g fat) every 30 min throughout the 6 h study day. An intravenous heparin infusion was initiated 2 h after the bolus, which resulted in a three- to fourfold increase in circulating NEFA level from baseline. Mean arterial stiffness as measured by digital volume pulse was higher during the consumption of SFA (P < 0·001) but not MUFA (P = 0·089) compared with the control. Overall insulin and gastric inhibitory peptide response was greater during the consumption of both fats compared with the control (P < 0·001); there was a second insulin peak in response to MUFA unlike SFA. Consumption of SFA resulted in higher levels of soluble intercellular adhesion molecule-1 (sI-CAM) at 330 min than that of MUFA or control (P ≤ 0·048). There was no effect of the test drinks on glucose, total nitrite, plasminogen activator inhibitor-1 or endothelin-1 concentrations. The present study indicates a potential negative impact of elevated NEFA derived from the consumption of SFA on arterial stiffness and sI-CAM levels. More studies are needed to fully investigate the impact of NEFA composition on risk factors for CVD.
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406
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Abstract
Traditionally, successful treatment of patients with type 2 diabetes mellitus (DM) has been defined strictly by achievement of targeted glycemic control, primarily using a stepped-care approach that begins with changes in lifestyle combined with oral therapy that is slowly intensified as disease progression advances and β-cell function declines. However, stepped care is often adjusted without regard to the mechanism of hyperglycemia or without long-term objectives. A more comprehensive definition of treatment success in patients with type 2 DM should include slowing or stopping disease progression and optimizing the reduction of all risk factors associated with microvascular and macrovascular disease complications. To achieve these broader goals, it is important to diagnose diabetes earlier in the disease course and to consider use of more aggressive combination therapy much earlier with agents that have the potential to slow or halt the progressive β-cell dysfunction and loss characteristic of type 2 DM. A new paradigm for managing patients with type 2 DM should address the concomitant risk factors and morbidities of obesity, hypertension, and dyslipidemia with equal or occasionally even greater aggressiveness than for hyperglycemia. The use of antidiabetes agents that may favorably address cardiovascular risk factors should be considered more strongly in treatment algorithms, although no pharmacological therapy is likely to be ultimately successful without concomitant synergistic lifestyle changes. Newer incretin-based therapies, such as glucagon-like peptide 1 receptor agonists and dipeptidyl peptidase 4 inhibitors, which appear to have a favorable cardiovascular safety profile as well as the mechanistic possibility for a favorable cardiovascular risk impact, are suitable for earlier inclusion as part of combination regimens aimed at achieving comprehensive treatment success in patients with type 2 DM.
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Affiliation(s)
- Mark W Stolar
- Clinical Medicine, Feinberg School of Medicine, 676 N Saint Clair, Ste 415, Chicago, IL 60611, USA.
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407
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Abstract
Recent experimental data suggest glucagon-like peptide 1 (GLP-1) and its analogs to have direct effects on the cardiovascular system, in addition to their classic glucoregulatory actions. These direct effects may be cardioprotective, contractility augmenting, and vasorelaxant. A few preliminary clinical trials appear to support a mechanical function improvement after GLP-1 administration to patients with a weakened left ventricle. Based on animal studies, diminished lethal injury to the postischemic reperfused myocardium appears to be a particularly promising prospect, awaiting to be tested in clinical settings.
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Affiliation(s)
- Marek Treiman
- Department of Biomedical Sciences and The Danish National Foundation Research Center for Heart Arrhythmia, University of Copenhagen, Copenhagen, Denmark.
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408
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Li ZY, Chen Y, Lin L, Kuai XY, Yu PL, Zhang HJ. Distribution of mitochondrial uncoupling protein 2 in the intestinal tract and its effect on GLP-1 secretion. Shijie Huaren Xiaohua Zazhi 2010; 18:3306-3312. [DOI: 10.11569/wcjd.v18.i31.3306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To detect the expression of mitochondrial uncoupling protein 2 (UCP2) in the intestinal tissue and to assess the possible effects of UCP2 on GLP-1 secretion in the gastrointestinal tract.
METHODS: The expression of UCP2 mRNA and protein in the gastrointestinal tract was detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot, respectively. Co-localization of UCP2 with GLP-1 was detected by immunohistochemistry. The level of serum GLP-1 was measured by enzyme-linked immunosorbent assay.
RESULTS: UCP2 was primarily expressed in mucosal epithelial cells and co-localized with GLP-1 in the gastrointestinal mucosa. Glucose administration induced strong expression of UCP2 in the colon of C57BL/6J mice. UCP2-deficient mice showed an increased glucose-induced GLP-1 secretion compared with wild-type littermates (6.9000 ± 0.25, 5.5600 ± 0.42 vs 3.5408 ± 0.18, both P < 0.01; 9.3500 ± 0.95, 7.8600 ± 0.25 vs 3.7322 ± 0.13, both P < 0.01). Taken together, these results suggest an inhibitory effect of UCP2 on glucose-induced GLP-1 secretion.
CONCLUSION: The expression of UCP2 in the mouse gastrointestinal tract can be strongly induced by glucose administration.UCP2 serves as a negative regulator of glucose-induced GLP-1 secretion.
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409
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Marx N, Burgmaier M, Heinz P, Ostertag M, Hausauer A, Bach H, Durst R, Hombach V, Walcher D. Glucagon-like peptide-1(1-37) inhibits chemokine-induced migration of human CD4-positive lymphocytes. Cell Mol Life Sci 2010; 67:3549-55. [PMID: 20495843 PMCID: PMC11115661 DOI: 10.1007/s00018-010-0396-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 04/12/2010] [Accepted: 04/29/2010] [Indexed: 11/30/2022]
Abstract
The present study examined the effect of GLP-1(1-37) on chemokine-induced CD4-positive lymphocyte migration as an early and critical step in atherogenesis. Pretreatment with GLP-1(1-37) reduced the SDF-induced migration of isolated human CD4-positive lymphocytes in a concentration-dependent manner. Similar effects were seen when RANTES was used as a chemokine. GLP-1(1-37)'s effect on CD4-positive lymphocyte migration was mediated through an early inhibition of chemokine-induced PI-3 kinase activity. Downstream, GLP-1(1-37) inhibited SDF-induced phosphorylation of MLC and cofilin and limited f-actin formation as well as ICAM3 translocation. Furthermore, exendin-4 inhibited SDF-induced migration of CD4-positive lymphocytes similarly to GLP-1(1-37), and transfection of these cells with GLP-1 receptor siRNA abolished GLP-1(1-37)'s action on chemokine-induced ICAM3 translocation, suggesting an effect mediated via the GLP-1 receptor. Thus, GLP-1(1-37) inhibits chemokine-induced CD4-positive lymphocyte migration by inhibition of the PI3-kinase pathway and via the GLP-1 receptor. This effect provides a potential novel mechanism for how GLP-1(1-37) may modulate vascular disease.
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Affiliation(s)
- Nikolaus Marx
- Department of Internal Medicine I-Cardiology, University of Aachen, Pauwelstr. 30, Aachen, Germany.
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410
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Hattori Y, Jojima T, Tomizawa A, Satoh H, Hattori S, Kasai K, Hayashi T. A glucagon-like peptide-1 (GLP-1) analogue, liraglutide, upregulates nitric oxide production and exerts anti-inflammatory action in endothelial cells. Diabetologia 2010; 53:2256-63. [PMID: 20593161 DOI: 10.1007/s00125-010-1831-8] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Accepted: 05/24/2010] [Indexed: 01/12/2023]
Abstract
AIMS/HYPOTHESIS Glucagon-like peptide-1 (GLP-1), a member of the proglucagon-derived peptide family, was seen to exert favourable actions on cardiovascular function in preclinical and clinical studies. The mechanisms through which GLP-1 modulates cardiovascular function are complex and incompletely understood. We thus investigated whether the GLP-1 analogue, liraglutide, which is an acylated GLP-1, has protective effects on vascular endothelial cells. METHODS Nitrite and nitrate were measured in medium with an automated nitric oxide detector. Endothelial nitric oxide synthase (eNOS) activation was assessed by evaluating the phosphorylation status of the enzyme and evaluating eNOS activity by citrulline synthesis. Nuclear factor kappaB (NF-kappaB) activation was assessed by reporter gene assay. RESULTS Liraglutide dose-dependently increased nitric oxide production in HUVECs. It also caused eNOS phosphorylation, potentiated eNOS activity and restored the cytokine-induced downregulation of eNOS (also known as NOS3) mRNA levels, which is dependent on NF-kappaB activation. We therefore examined the effect of liraglutide on TNFalpha-induced NF-kappaB activation and NF-kappaB-dependent expression of proinflammatory genes. Liraglutide dose-dependently inhibited NF-kappaB activation and TNFalpha-induced IkappaB degradation. It also reduced TNFalpha-induced MCP-1 (also known as CCL2), VCAM1, ICAM1 and E-selectin mRNA expression. Liraglutide-induced enhancement of nitric oxide production and suppression of NF-kappaB activation were attenuated by the AMP-activated protein kinase (AMPK) inhibitor compound C or AMPK (also known as PRKAA1) small interfering RNA. Indeed, liraglutide induced phosphorylation of AMPK, which occurs through a signalling pathway independent of cyclic AMP. CONCLUSIONS/INTERPRETATION Liraglutide exerts an anti-inflammatory effect on vascular endothelial cells by increasing nitric oxide production and suppressing NF-kappaB activation, partly at least through AMPK activation. These effects may explain some of the observed vasoprotective properties of liraglutide, as well as its beneficial effects on the cardiovascular system.
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Affiliation(s)
- Y Hattori
- Department of Endocrinology and Metabolism, Dokkyo University School of Medicine, Mibu, Tochigi 321-0293, Japan.
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411
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Pinkney J, Fox T, Ranganath L. Selecting GLP-1 agonists in the management of type 2 diabetes: differential pharmacology and therapeutic benefits of liraglutide and exenatide. Ther Clin Risk Manag 2010; 6:401-11. [PMID: 20856686 PMCID: PMC2940748 DOI: 10.2147/tcrm.s7313] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Indexed: 12/26/2022] Open
Abstract
Failure of secretion of the incretin hormone glucagon-like peptide-1 (GLP-1) plays a prominent role in type 2 diabetes, and restoration of GLP-1 action is an important therapeutic objective. Although the short duration of action of GLP-1 renders it unsuited to therapeutic use, 2 long-acting GLP-1 receptor agonists, exenatide and liraglutide, represent a significant advance in treatment. In controlled trials, both produce short-term glucose-lowering effects, with the reduction in hemoglobin A(1c) of up to 1.3%. These responses are often superior to those observed with additional oral agents. However, unlike sulfonylureas, thiazolidinediones, or insulin, all of which lead to significant weight gain, GLP-1 receptor agonists uniquely result in long-term weight loss of around 5 kg, and higher doses may enhance this further. Reduction in blood pressure of 2-7 mm Hg also has been observed. Both drugs produce transient mild gastrointestinal side effects; although mild hypoglycemia can occur, this is usually in combination with other hypoglycemic therapies. However, serious hypoglycemia and acute pancreatitis are rare. The once-daily dosage of liraglutide makes it more convenient than twice-daily dosage of prandial exenatide, and a superior glucose-lowering effect was observed in the only head-to-head comparison reported so far. Besides cost, these considerations currently favor liraglutide over exenatide. Further studies are needed to confirm long-term safety, and most importantly, that short-term benefits translate into long-term reductions of diabetes-related cardiovascular events and other complications.
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Affiliation(s)
- Jonathan Pinkney
- Department of Diabetes and Endocrinology, Peninsula College of Medicine and Dentistry, Plymouth, United Kingdom
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412
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Leahy JL, Hirsch IB, Peterson KA, Schneider D. Targeting beta-cell function early in the course of therapy for type 2 diabetes mellitus. J Clin Endocrinol Metab 2010; 95:4206-16. [PMID: 20739389 DOI: 10.1210/jc.2010-0668] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVE This report examines current perspectives regarding likely mechanisms of beta-cell failure in type 2 diabetes and their clinical implications for protecting or sparing beta-cells early in the disease progression. In addition, it considers translation strategies to incorporate relevant scientific findings into educational initiatives targeting clinical practice behavior. PARTICIPANTS On January 10, 2009, a working group of basic researchers, clinical endocrinologists, and primary care physicians met to consider whether current knowledge regarding pancreatic beta-cell defects justifies retargeting and retiming treatment for clinical practice. Based on this meeting, a writing group comprised of four meeting participants subsequently prepared this consensus statement. The conference was convened by The Endocrine Society and funded by an unrestricted educational grant from Novo Nordisk. EVIDENCE Participants reviewed and discussed published literature, plus their own unpublished data. CONSENSUS PROCESS The summary and recommendations were supported unanimously by the writing group as representing the consensus opinions of the working group. CONCLUSIONS Workshop participants strongly advocated developing new systems to address common barriers to glycemic control and recommended several initial steps toward this goal. These recommendations included further studies to establish the clinical value of pharmacological therapies, continuing basic research to elucidate the nature and mechanisms of beta-cell failure in type 2 diabetes mellitus, and exploring new educational approaches to promote pathophysiology-based clinical practices. The Endocrine Society has launched a new website to continue the discussion between endocrinologists and primary care physicians on beta-cell pathophysiology in type 2 diabetes and its clinical implications. Join the conversation at http://www.betacellsindiabetes.org
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Affiliation(s)
- Jack L Leahy
- Endocrine Unit, University of Vermont College of Medicine Colchester Research Facility, 208 South Park Drive, Colchester, Vermont 05446, USA.
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413
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Erdogdu O, Nathanson D, Sjöholm A, Nyström T, Zhang Q. Exendin-4 stimulates proliferation of human coronary artery endothelial cells through eNOS-, PKA- and PI3K/Akt-dependent pathways and requires GLP-1 receptor. Mol Cell Endocrinol 2010; 325:26-35. [PMID: 20452396 DOI: 10.1016/j.mce.2010.04.022] [Citation(s) in RCA: 174] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 04/20/2010] [Accepted: 04/27/2010] [Indexed: 12/20/2022]
Abstract
Endothelial cells have a robust capacity to proliferate and participate in angiogenesis, which underlies the maintenance of intimal layer integrity. We previously showed the presence of the GLP-1 receptor in human coronary artery endothelial cells (HCAECs) and the ameliorative actions of GLP-1 on endothelial dysfunction in type 2 diabetic patients. Here, we have studied the effect of exendin-4 on cell proliferation and its underlying mechanisms in HCAECs. Incubation of HCAECs with exendin-4 resulted in a dose-dependent increase in DNA synthesis and an increased cell number, associated with an enhanced eNOS and Akt activation, which were inhibited by PKA, PI3K, Akt or eNOS inhibitors and abolished by a GLP-1 receptor antagonist. Similar effects were obtained by applying GLP-1 (7-36) or GLP-1 (9-36). Co-incubation of exendin-4 and GLP-1 did not show additive effects. Our results suggest that exendin-4 stimulates proliferation of HCAECs through PKA-PI3K/Akt-eNOS activation pathways via a GLP-1 receptor-dependent mechanism.
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Affiliation(s)
- O Erdogdu
- Karolinska Institutet, Department of Clinical Science and Education, Unit for Diabetes Research, Södersjukhuset, Stockholm, Sweden
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414
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Medlin MD, Staus DP, Dubash AD, Taylor JM, Mack CP. Sphingosine 1-phosphate receptor 2 signals through leukemia-associated RhoGEF (LARG), to promote smooth muscle cell differentiation. Arterioscler Thromb Vasc Biol 2010; 30:1779-86. [PMID: 20702813 DOI: 10.1161/atvbaha.110.209395] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE The goals of this study were to identify the signaling pathway by which sphingosine 1-phosphate (S1P) activates RhoA in smooth muscle cells (SMC) and to evaluate the contribution of this pathway to the regulation of SMC phenotype. METHODS AND RESULTS Using a combination of receptor-specific agonists and antagonists we identified S1P receptor 2 (S1PR2) as the major S1P receptor subtype that regulates SMC differentiation marker gene expression. Based on the known coupling properties of S1PR2 and our demonstration that overexpression of Galpha(12) or Galpha(13) increased SMC-specific promoter activity, we next tested whether the effects of S1P in SMC were mediated by the regulator of G protein-signaling-Rho guanine exchange factors (RGS-RhoGEFs) (leukemia-associated RhoGEF [LARG], PDZ-RhoGEF [PRG], RhoGEF [p115]). Although each of the RGS-RhoGEFs enhanced actin polymerization, myocardin-related transcription factor-A nuclear localization, and SMC-specific promoter activity when overexpressed in 10T1/2 cells, LARG exhibited the most robust effect and was the only RGS-RhoGEF activated by S1P in SMC. Importantly, siRNA-mediated depletion of LARG significantly inhibited the activation of RhoA and SMC differentiation marker gene expression by S1P. Knockdown of LARG had no effect on SMC proliferation but promoted SMC migration as measured by scratch wound and transwell assays. CONCLUSIONS These data indicate that S1PR2-dependent activation of RhoA in SMC is mediated by LARG and that this signaling mechanism promotes the differentiated SMC phenotype.
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Affiliation(s)
- Matt D Medlin
- Department of Pathology, University of North Carolina, Chapel Hill, NC, USA
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415
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Marney A, Kunchakarra S, Byrne L, Brown NJ. Interactive hemodynamic effects of dipeptidyl peptidase-IV inhibition and angiotensin-converting enzyme inhibition in humans. Hypertension 2010; 56:728-33. [PMID: 20679179 DOI: 10.1161/hypertensionaha.110.156554] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Dipeptidyl peptidase-IV inhibitors improve glucose homeostasis in type 2 diabetics by inhibiting degradation of the incretin hormones. Dipeptidyl peptidase-IV inhibition also prevents the breakdown of the vasoconstrictor neuropeptide Y and, when angiotensin-converting enzyme (ACE) is inhibited, substance P. This study tested the hypothesis that dipeptidyl peptidase-IV inhibition would enhance the blood pressure response to acute ACE inhibition. Subjects with the metabolic syndrome were treated with 0 mg of enalapril (n=9), 5 mg of enalapril (n=8), or 10 mg enalapril (n=7) after treatment with sitagliptin (100 mg/day for 5 days and matching placebo for 5 days) in a randomized, cross-over fashion. Sitagliptin decreased serum dipeptidyl peptidase-IV activity (13.08±1.45 versus 30.28±1.76 nmol/mL/min during placebo; P≤0.001) and fasting blood glucose. Enalapril decreased ACE activity in a dose-dependent manner (P<0.001). Sitagliptin lowered blood pressure during enalapril (0 mg; P=0.02) and augmented the hypotensive response to 5 mg of enalapril (P=0.05). In contrast, sitagliptin attenuated the hypotensive response to 10 mg of enalapril (P=0.02). During sitagliptin, but not during placebo, 10 mg of enalapril significantly increased heart rate and plasma norepinephrine concentrations. There was no effect of 0 or 5 mg of enalapril on heart rate or norepinephrine after treatment with either sitagliptin or placebo. Sitagliptin enhanced the dose-dependent effect of enalapril on renal blood flow. In summary, sitagliptin lowers blood pressure during placebo or submaximal ACE inhibition; sitagliptin activates the sympathetic nervous system to diminish hypotension when ACE is maximally inhibited. This study provides the first evidence for an interactive hemodynamic effect of dipeptidyl peptidase-IV and ACE inhibition in humans.
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Affiliation(s)
- Annis Marney
- Division of Endocrinology, Department of Medicine, University of Vermont, Colchester, VT 05446, USA.
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416
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Potential role of TCF7L2 gene variants on cardiac sympathetic/parasympathetic activity. Eur J Hum Genet 2010; 18:1333-8. [PMID: 20648057 DOI: 10.1038/ejhg.2010.117] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Variants in transcription factor 7-like 2 (266096218TCF7L2266096218USuser266096218Gene names have been italicized per house style. Please check and confirm whether there are other instances that need to be italicized or instances where italics have been inappropriately applied.) gene have been found strongly associated with an increased risk of type 2 diabetes, as well as with an impairment of glucagon-like peptide-1 (GLP-1) signalling chain. In rats, stimulation of central GLP-1 receptors increases heart rate and activates autonomic regulatory neurons. We aimed to evaluate the potential role of TCF7L2 gene polymorphisms on sympathovagal response in relation to changes in plasma insulin and/or GLP-1 concentration after glucose ingestion. Genotyping was performed for rs12255372 and rs7903146 TCF7L2 gene variants in 250 non-related healthy volunteers (mean age 27±3 years). Consistent with previous reports, both single-nucleotide polymorphisms were in strong linkage disequilibrium (D'=0.87, r(2)=0.76). A subset of 167 patients underwent an oral glucose tolerance test while a continuous recording of heart rate variability was performed. At baseline, no differences in fasting plasma insulin, in GLP-1 levels and in LF/HF (low frequency/high frequency) ratio between the three genotypes were found. Along with glucose ingestion TT subjects had lower INS(AUC) (insulin area under curve), as well as higher LF/HF(AUC) (LF/HF area under curve) values. No difference in GLP-1(AUC) (GLP-1 area under curve) between TCF7L2 gene variants was found. A multivariate analysis including multiple covariates showed that only INS(AUC,) GLP-1(AUC) and TCF7L2 gene variants were independently associated with LF/HF(AUC). In conclusion, TT genotype of rs12255372 and rs7903146 TCF7L2 gene variants is associated with lower insulin secretion and higher cardiosympathetic activity. Moreover, such effect is independent of GLP-1 and insulin plasma concentrations suggesting a potential role of such gene variants in increasing cardiovascular risk through enhanced sympathetic nervous system activity.
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417
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Abstract
Type 2 diabetes mellitus is a complicated metabolic disease affecting millions of individuals worldwide. The medications used to manage the disease are based on different pharmacologic approaches, including decreasing hepatic gluconeogenesis, stimulating pancreatic insulin production, slowing polysaccharide digestion, and increasing insulin sensitivity in muscle, liver, and fat to lower blood glucose. Incretin-based therapies, including glucagon-like peptide-1 (GLP-1) receptor agonists, mimic the effects of native GLP-1, while dipeptidyl peptidase-4 inhibitors increase circulating concentrations of endogenous GLP-1. This review focuses on means by which primary care physicians might evaluate the utility of pharmacologic agents based on their relation to the pathogenesis of type 2 diabetes. In general, patients with type 2 diabetes should be treated to their lowest targeted glycemic goals as soon as they are diagnosed, for as long as possible, as safely as possible, and as rationally as possible.
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Affiliation(s)
- Jeff Unger
- Metabolic Studies, Catalina Research Institute, Chino, CA 91710, USA.
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418
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De Caterina R, Madonna R, Sourij H, Wascher T. Glycaemic control in acute coronary syndromes: prognostic value and therapeutic options. Eur Heart J 2010; 31:1557-64. [PMID: 20519242 DOI: 10.1093/eurheartj/ehq162] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Type 2 diabetes and acute coronary syndromes (ACS) are widely interconnected. Individuals with type 2 diabetes are more likely than non-diabetic subjects to experience silent or manifest episodes of myocardial ischaemia as the first presentation of coronary artery disease. Insulin resistance, inflammation, microvascular disease, and a tendency to thrombosis are common in these patients. Intensive blood glucose control with intravenous insulin infusion has been demonstrated to significantly reduce morbidity and mortality in critically ill hyperglycaemic patients admitted to an intensive care unit (ICU). Direct glucose toxicity likely plays a crucial role in explaining the clinical benefits of intensive insulin therapy in such critical patients. However, the difficult implementation of nurse-driven protocols for insulin infusion able to lead to rapid and effective blood glucose control without significant episodes of hypoglycaemia has led to poor implementations of insulin infusion protocols in coronary care units, and cardiologists now to consider alternative drugs for this purpose. New intravenous or oral agents include the incretin glucagon-like peptide 1 (GLP1), its analogues, and dipeptidyl peptidase-4 inhibitors, which potentiate the activity of GLP1 and thus enhance glucose-dependent insulin secretion. Improved glycaemic control with protective effects on myocardial and vascular tissues, with lesser side effects and a better therapeutic compliance, may represent an important therapeutic potential for this class of drugs in acutely ill patients in general and patients with ACS in particular. Such drugs should be known by practicing cardiologists for their possible use in ICUs in the years to come.
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Affiliation(s)
- Raffaele De Caterina
- Institute of Cardiology and Center of Excellence on Aging, G. d'Annunzio University-Chieti, C/o Ospedale SS. Annunziata, Via dei Vestini, I-66013 Chieti, Italy.
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419
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Hiki M, Shimada K, Kiyanagi T, Fukao K, Hirose K, Ohsaka H, Fukushima Y, Kume A, Matsumori R, Sumiyoshi K, Miyazaki T, Ohmura H, Kurata T, Miida T, Daida H. Single administration of alpha-glucosidase inhibitors on endothelial function and incretin secretion in diabetic patients with coronary artery disease - Juntendo University trial: effects of miglitol on endothelial vascular reactivity in type 2 diabetic patients with coronary heart disease (J-MACH) -. Circ J 2010; 74:1471-8. [PMID: 20519875 DOI: 10.1253/circj.cj-10-0013] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Post-prandial hyperglycemia, hyperlipidemia, and endothelial dysfunction play an important role in the pathogenesis of atherosclerosis. Improvement in post-prandial hyperglycemia on alpha-glucosidase inhibitors (alpha-GIs) is associated with a risk reduction of cardiovascular diseases, but the post-prandial effects of alpha-GIs on endothelial function and incretin secretion in type 2 diabetic patients with coronary artery disease (CAD) remain unclear. METHODS AND RESULTS The post-prandial effects of a single administration of miglitol and voglibose on endothelial function and changing levels of glucose, insulin, lipids, glucagon-like peptide (GLP)-1, and gastric inhibitory polypeptide (GIP) were compared after a standard meal loading in 11 diabetic patients with CAD, using a placebo-controlled cross-over design. The changing levels of glucose, insulin and triglycerides at 60 min were significantly lower in the miglitol group than in the voglibose and placebo groups (all P<0.01). GLP-1 levels were significantly higher at 120 min (P<0.05) and GIP levels were significantly lower at 30 min and 60 min (P<0.05) in the miglitol group compared to other treatments. The reactive hyperemia duration at 120 min was significantly maintained in the miglitol group compared to the other groups. CONCLUSIONS A single administration of miglitol significantly improved post-prandial glucose/lipid metabolism, incretin secretion, and endothelial dysfunction in diabetic patients with CAD, suggesting that miglitol may be a useful anti-atherogenic agent (UMIN000002264).
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Affiliation(s)
- Makoto Hiki
- Department of Cardiovascular Medicine, Juntendo University School of Medicine, Tokyo, Japan
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420
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McAdam-Marx C, Gaebler JA, Bellows BK, Brixner DI. Contemporary management of patients with Type 2 diabetes. Expert Rev Cardiovasc Ther 2010; 8:767-70. [DOI: 10.1586/erc.10.62] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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421
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Dokken BB, Hilwig WR, Teachey MK, Panchal RA, Hubner K, Allen D, Rogers DC, Kern KB. Glucagon-like peptide-1 (GLP-1) attenuates post-resuscitation myocardial microcirculatory dysfunction. Resuscitation 2010; 81:755-60. [DOI: 10.1016/j.resuscitation.2010.01.031] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 01/12/2010] [Accepted: 01/18/2010] [Indexed: 02/02/2023]
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422
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[Incretins: do they exert cardiovascular effects?]. Herz 2010; 35:130-8. [PMID: 20467925 DOI: 10.1007/s00059-010-3333-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The physiological effects of the incretin hormone glucagon-like peptide-(GLP-)1 have contributed to the important role that incretin-based therapies with GLP-1 analogs or dipeptidyl peptidase-(DPP-)4 inhibitors already play in type 2 diabetes treatment. This development is not only due to the glucose-dependent insulinotropic effect of GLP-1 as well as the positive effects on beta cell function and, probably, beta cell mass, but also to the beneficial effects on body weight.Lately, the data on positive cardiovascular effects of GLP-1 have been growing. In animal models, GLP-1 improves left ventricular function and diminishes myocardial defects in ischemia models. In clinical studies with GLP-1 analogs, a normalization of blood pressure was observed and some of the data from animal studies after myocardial infarction or after invasive cardiologic or cardiosurgical interventions were also found under clinical conditions in humans. Additionally, an improvement of cardiovascular surrogate parameters was observed with incretin-based therapies. This review gives an overview on the cardiovascular effects of GLP-1 and incretin-based therapies.
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423
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Bhashyam S, Fields AV, Patterson B, Testani JM, Chen L, Shen YT, Shannon RP. Glucagon-like peptide-1 increases myocardial glucose uptake via p38alpha MAP kinase-mediated, nitric oxide-dependent mechanisms in conscious dogs with dilated cardiomyopathy. Circ Heart Fail 2010; 3:512-21. [PMID: 20466848 DOI: 10.1161/circheartfailure.109.900282] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND We have shown that glucagon-like peptide-1 (GLP-1[7-36] amide) stimulates myocardial glucose uptake in dilated cardiomyopathy (DCM) independent of an insulinotropic effect. The cellular mechanisms of GLP-1-induced myocardial glucose uptake are unknown. METHODS AND RESULTS Myocardial substrates and glucoregulatory hormones were measured in conscious, chronically instrumented dogs at control (n=6), DCM (n=9) and DCM after treatment with a 48-hour infusion of GLP-1 (7-36) amide (n=9) or vehicle (n=6). GLP-1 receptors and cellular pathways implicated in myocardial glucose uptake were measured in sarcolemmal membranes harvested from the 4 groups. GLP-1 stimulated myocardial glucose uptake (DCM: 20+/-7 nmol/min/g; DCM+GLP-1: 61+/-12 nmol/min/g; P=0.001) independent of increased plasma insulin levels. The GLP-1 receptors were upregulated in the sarcolemmal membranes (control: 98+/-2 density units; DCM: 256+/-58 density units; P=0.046) and were expressed in their activated (65 kDa) form in DCM. The GLP-1-induced increases in myocardial glucose uptake did not involve adenylyl cyclase or Akt activation but was associated with marked increases in p38alpha MAP kinase activity (DCM+vehicle: 97+/-22 pmol ATP/mg/min; DCM+GLP-1: 170+/-36 pmol ATP/mg/min; P=0.051), induction of nitric oxide synthase 2 (DCM+vehicle: 151+/-13 density units; DCM+GLP-1: 306+/-12 density units; P=0.001), and GLUT-1 translocation (DCM+vehicle: 21+/-3% membrane bound; DCM+GLP-1: 39+/-3% membrane bound; P=0.005). The effects of GLP-1 on myocardial glucose uptake were blocked by pretreatment with the p38alpha MAP kinase inhibitor or the nonspecific nitric oxide synthase inhibitor nitro-l-arginine. CONCLUSIONS GLP-1 stimulates myocardial glucose uptake through a non-Akt-1-dependent mechanism by activating cellular pathways that have been identified in mediating chronic hibernation and the late phase of ischemic preconditioning.
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Affiliation(s)
- Siva Bhashyam
- Department of Medicine, Allegheny General Hospital, Pittsburgh, Pa 19104, USA
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424
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Age-related change in endothelial and microvessel function and therapeutic consequences. ACTA ACUST UNITED AC 2010. [DOI: 10.1017/s0959259810000158] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
SummaryAs the absolute numbers and proportion of older adults increases across most of the developed world, a greater understanding of the aetiopathogenic mechanisms of the increased vascular risk and their therapeutic implications becomes essential to all clinicians assessing and managing the geriatric patient. The role of endothelial function and the microcirculation is increasingly recognized in the maintenance of adequate perfusion, and their dysfunction is thought to be an early and potentially reversible mechanism by which age acts to increase cardiovascular risk.Here we review evidence that altered microvascular function appears before other recognized predictors of vascular disease, and progresses from childhood to late adult life, preceding fulminant atherosclerotic or arteriosclerotic disease. Low birth-weight babies have reduced endothelial function in skin microvessels at 3 months, and by age ten brachial artery endothelial function is reduced in comparison with normal birth-weight babies. In overweight/obese adolescent children with clustering of traditional cardiovascular disease risk factors, endothelial function is lower compared with normal weight children and this appears to persist into early adulthood. Adult ageing is associated with impaired microvessel endothelial function and an increase in capillary blood pressure, independent of brachial artery blood pressure. Biological and lifestyle factors that influence microvessel function include body fat and visceral adiposity, sex hormone status, diet and physical activity.Exploration of the therapeutic implications for management of endothelial dysfunction remains in embryonic state. The use of ACE-inhibitors, angiotensin receptor blockers and direct renin inhibitors in patients with evidence of microvascular damage such as retinopathy and microalbuminuria has been established; however, in the general older population the benefit has yet to be established. Therefore current recommendations are to screen for microvascular damage and if present target treatments after control of other vascular risk factors such as hypertension.
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425
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Oeseburg H, de Boer RA, Buikema H, van der Harst P, van Gilst WH, Silljé HHW. Glucagon-like peptide 1 prevents reactive oxygen species-induced endothelial cell senescence through the activation of protein kinase A. Arterioscler Thromb Vasc Biol 2010; 30:1407-14. [PMID: 20448207 DOI: 10.1161/atvbaha.110.206425] [Citation(s) in RCA: 192] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
OBJECTIVE Endothelial cell senescence is an important contributor to vascular aging and is increased under diabetic conditions. Here we investigated whether the antidiabetic hormone glucagon-like peptide 1 (GLP-1) could prevent oxidative stress-induced cellular senescence in endothelial cells. METHODS AND RESULTS In Zucker diabetic fatty rats, a significant 2-fold higher level of vascular senescence was observed compared with control lean rats. Dipeptidyl-peptidase 4 (DPP-4) inhibition significantly increased GLP-1 levels in these animals and reduced senescence almost to lean animal levels. In vitro studies with human umbilical vein endothelial cells showed that GLP-1 had a direct protective effect on oxidative stress (H(2)O(2))-induced senescence and was able to attenuate oxidative stress-induced DNA damage and cellular senescence. The GLP-1 analogue exendin-4 provided similar results, whereas exendin fragment 9-39, a GLP-1 receptor antagonist, abolished this effect. Intracellular signaling by the phosphoinositide 3-kinase (PI3K)/Akt survival pathway did not appear to be involved. Further analysis revealed that GLP-1 activates the cAMP response element-binding (CREB) transcription factor in a cAMP/protein kinase A (PKA)-dependent manner, and inhibition of the cAMP/PKA pathway abolished the GLP-1 protective effect. Expression analysis revealed that GLP-1 can induce the oxidative defense genes HO-1 and NQO1. CONCLUSIONS Dipeptidyl-peptidase 4 inhibition protects against vascular senescence in a diabetic rat model. In vitro studies with human umbilical vein endothelial cells showed that reactive oxygen species-induced senescence was attenuated by GLP-1 in a receptor-dependent manner involving downstream PKA signaling and induction of antioxidant genes.
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Affiliation(s)
- Hisko Oeseburg
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Antonius Deusinglaan 1, 9713AV Groningen, the Netherlands
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426
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Koska J, Schwartz EA, Mullin MP, Schwenke DC, Reaven PD. Improvement of postprandial endothelial function after a single dose of exenatide in individuals with impaired glucose tolerance and recent-onset type 2 diabetes. Diabetes Care 2010; 33:1028-30. [PMID: 20200309 PMCID: PMC2858168 DOI: 10.2337/dc09-1961] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Endothelial dysfunction is frequently present in individuals with insulin resistance or type 2 diabetes and can be induced by high-fat or high-carbohydrate meals. Because exenatide reduces postprandial glucose and lipid excursions, we hypothesized that it may also improve postprandial endothelial function. RESEARCH DESIGN AND METHODS In a double-blinded randomized crossover design, postprandial endothelial function was examined in 28 individuals with impaired glucose tolerance or recent-onset type 2 diabetes after a single injection of exenatide or placebo given just before a high-fat meal. Endothelial function was determined with peripheral arterial tonometry pre- and postprandially. RESULTS Postprandial endothelial function was higher after exenatide compared with placebo (P = 0.0002). In the placebo phase, postprandial change in endothelial function was inversely associated with mean postprandial concentrations of triglycerides (r = -0.62, P = 0.0004). Changes in postprandial triglyceride concentrations explained 64% of exenatide's effect on postprandial endothelial function. CONCLUSIONS Exenatide ameliorates postprandial endothelial dysfunction after a high-fat meal.
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Affiliation(s)
- Juraj Koska
- Department of Endocrinology, Phoenix VA Health Care System, Phoenix, Arizona, USA.
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427
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Abstract
Incretin mimetics offer a new modality in diabetes treatment. This modality is based on the effects of the naturally occurring glucoregulatory gut hormone glucagon-like peptide-1 (GLP-1), which counteracts several pathophysiologic traits in type 2 diabetes. GLP-1 receptor agonists with extended half-lives entailing fewer injections and presumably an improved throughout-the-day glycemic control are in clinical development. This article summarizes the physiologic effects of GLP-1; the effects of the already marketed GLP-1 analogues for daily dosing, exenatide and liraglutide; and reviews the presently published data (with emphasis on clinical pharmacokinetics, efficacy, and safety) on GLP-1 agonists, which currently are in development and intended for once-weekly dosing: albiglutide/albugon, CJC-1131, CJC-1134-PC, exenatide once weekly, and taspoglutide.
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Affiliation(s)
- Mikkel Christensen
- Department of Internal Medicine F, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
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428
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Abstract
Obesity is a major risk factor for the development of diabetes and predisposes individuals to hypertension and dyslipidaemia. Together these pathologies increase the risk for cardiovascular disease (CVD), the major cause of morbidity and mortality in type 2 diabetes mellitus (T2DM). Worsening trends in obesity and T2DM raise a serious conundrum, namely, how to control blood glucose, blood pressure, and lipids when many antidiabetic agents cause weight gain and thereby exacerbate other cardiovascular risk factors associated with T2DM. Further, evidence suggests that some established antihypertensive agents may worsen glucose intolerance. Many patients who are obese, hypertensive, and/or hyperlipidaemic fail to achieve blood pressure, lipid and glycaemic goals, and this failure may in part be explained by physician reluctance to utilize complex combination regimens for fear of off-target effects. Thus, a clear need exists for clinicians to understand the risks and benefits of different pharmacologic, and indeed non-pharmacologic, options in order to maximize treatment outcomes. While intensive lifestyle modification remains an elusive gold standard, newer diabetes targets, including the incretin axis, may offer greater cardiovascular risk reduction than other antidiabetes therapies, although definitive clinical trial data are needed. The glucagon-like peptide-1 (GLP-1) receptor agonists exenatide and liraglutide and the dipeptidyl peptidase-4 (DPP-4) inhibitors sitagliptin and vildagliptin effectively lower HbA1c; exenatide and liraglutide reduce weight and blood pressure and improve lipid profiles. Sitagliptin and vildagliptin are weight neutral but also appear to improve lipid profiles. Integration of incretin therapies into the therapeutic armamentarium is a promising approach to improving outcomes in T2DM, and perhaps even in reducing complications of T2DM, such as co-morbid hypertension and dyslipidaemia. Additional long-term studies, including CVD end-point studies, will be necessary to determine the appropriate places for incretin-based therapies in treatment algorithms.
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Affiliation(s)
- Kevin Niswender
- Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Tennessee Valley Healthcare System and Vanderbilt University School of Medicine, Nashville, TN, USA.
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429
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Arakawa M, Mita T, Azuma K, Ebato C, Goto H, Nomiyama T, Fujitani Y, Hirose T, Kawamori R, Watada H. Inhibition of monocyte adhesion to endothelial cells and attenuation of atherosclerotic lesion by a glucagon-like peptide-1 receptor agonist, exendin-4. Diabetes 2010; 59:1030-7. [PMID: 20068138 PMCID: PMC2844811 DOI: 10.2337/db09-1694] [Citation(s) in RCA: 395] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Exogenous administration of glucagon-like peptide-1 (GLP-1) or GLP-1 receptor agonists such as an exendin-4 has direct beneficial effects on the cardiovascular system. However, their effects on atherosclerogenesis have not been elucidated. The aim of this study was to investigate the effects of GLP-1 on accumulation of monocytes/macrophages on the vascular wall, one of the earliest steps in atherosclerogenesis. RESEARCH DESIGN AND METHODS After continuous infusion of low (300 pmol . kg(-1) . day(-1)) or high (24 nmol . kg(-1) . day(-1)) dose of exendin-4 in C57BL/6 or apolipoprotein E-deficient mice (apoE(-/-)), we evaluated monocyte adhesion to the endothelia of thoracic aorta and arteriosclerotic lesions around the aortic valve. The effects of exendin-4 were investigated in mouse macrophages and human monocytes. RESULTS Treatment with exendin-4 significantly inhibited monocytic adhesion in the aortas of C57BL/6 mice without affecting metabolic parameters. In apoE(-/-) mice, the same treatment reduced monocyte adhesion to the endothelium and suppressed atherosclerogenesis. In vitro treatment of mouse macrophages with exendin-4 suppressed lipopolysaccharide-induced mRNA expression of tumor necrosis factor-alpha and monocyte chemoattractant protein-1, and suppressed nuclear translocation of p65, a component of nuclear factor-kappaB. This effect was reversed by either MDL-12330A, a cAMP inhibitor or PKI(14-22), a protein kinase A-specific inhibitor. In human monocytes, exendin-4 reduced the expression of CD11b. CONCLUSIONS Our data suggested that GLP-1 receptor agonists reduced monocyte/macrophage accumulation in the arterial wall by inhibiting the inflammatory response in macrophages, and that this effect may contribute to the attenuation of atherosclerotic lesion by exendin-4.
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Affiliation(s)
- Masayuki Arakawa
- Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Tomoya Mita
- Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo, Japan
- Corresponding author: Tomoya Mita, , or Hirotaka Watada,
| | - Kosuke Azuma
- Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Chie Ebato
- Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Hiromasa Goto
- Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Takashi Nomiyama
- Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Yoshio Fujitani
- Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo, Japan
- Center for Therapeutic Innovations in Diabetes, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Takahisa Hirose
- Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo, Japan
- Center for Therapeutic Innovations in Diabetes, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Ryuzo Kawamori
- Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo, Japan
- Center for Therapeutic Innovations in Diabetes, Juntendo University Graduate School of Medicine, Tokyo, Japan
- Sportology Center, Juntendo University Graduate School of Medicine, Tokyo, Japan
- Center for Beta Cell Biology and Regeneration, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Hirotaka Watada
- Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo, Japan
- Sportology Center, Juntendo University Graduate School of Medicine, Tokyo, Japan
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430
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Sjöholm Å. Liraglutide Therapy for Type 2 Diabetes: Overcoming Unmet Needs. Pharmaceuticals (Basel) 2010; 3:764-781. [PMID: 27713278 PMCID: PMC4033979 DOI: 10.3390/ph3030764] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 03/03/2010] [Accepted: 03/19/2010] [Indexed: 12/17/2022] Open
Abstract
Although advances have been achieved in the management of type 2 diabetes, current treatment options for patients with this disease still fail to address disease progression, glycaemic control remains suboptimal and therapies are often associated with weight gain and hypoglycaemia. Thus, new antidiabetes therapies are being sought. Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are incretin hormones that have been the recent focus of research. The physiological action of GLP-1, in particular, has demonstrated its potential in addressing the therapeutic needs of patients with type 2 diabetes. To exploit this action, liraglutide, a human GLP-1 analogue that shares 97% of its amino acid sequence identity with native GLP-1, has been developed. In a recent phase 3 trial programme (LEAD, Liraglutide Effect and Action in Diabetes), treatment with liraglutide was associated with substantial improvements in glycaemic control and low risk of hypoglycaemia. In addition, reductions in weight and systolic blood pressure were reported. There is also an indication that liraglutide is capable of improving β-cell function and increasing β-cell mass. Thus, liraglutide may overcome the limitations with current therapies and help to address the unmet clinical needs of patients with type 2 diabetes.
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Affiliation(s)
- Åke Sjöholm
- Karolinska Institutet, Department of Clinical Science and Education, Division of Internal Medicine, Unit for Diabetes Research, Södersjukhuset, SE-118 83 Stockholm, Sweden.
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431
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Abstract
Rates of type 2 diabetes, obesity and their associated detrimental cardiovascular effects are rapidly increasing. Despite the availability of several treatment options for type 2 diabetes and the use of intensive regimens combining several antidiabetic drugs, less than one-half of all patients reach a target glycosylated hemoglobin level of less than 7%. Disease progression due to ongoing deterioration of pancreatic islet cell health and beta-cell function is likely responsible. Therefore, there is a need to identify new pharmacological compounds that may not only treat hyperglycemia, but may also correct impaired glucose homeostasis and preserve endogenous beta-cell function. Identification and characterization of the incretin system and its effect on glucose homeostasis have resulted in the development of new antidiabetic agents that target these concerns. The current review examines the incretin effect and the pharmacological agents that have been developed based on the understanding of this physiological system. The influence of incretins on the cardiovascular system beyond the proatherogenic effect of type 2 diabetes will also be discussed.
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Affiliation(s)
- Paul E Szmitko
- Division of General Internal Medicine, St. Michael's Hospital, University of Toronto, 30 Bond Street, Toronto, Ontario, Canada
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432
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Okerson T, Yan P, Stonehouse A, Brodows R. Effects of exenatide on systolic blood pressure in subjects with type 2 diabetes. Am J Hypertens 2010; 23:334-9. [PMID: 20019672 DOI: 10.1038/ajh.2009.245] [Citation(s) in RCA: 148] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND The majority of patients with type 2 diabetes mellitus have blood pressure (BP) exceeding the recommended value of <130/80 mm Hg. Optimal control of hyperglycemia and hypertension has been shown to reduce the incidence of macrovascular and microvascular complications due to diabetes. Treatment with the GLP-1 receptor agonist exenatide, previously demonstrated to reduce hemoglobin A(1C) and weight in subjects with type 2 diabetes, was associated with BP reduction in several studies. METHODS This analysis explored the effects of exenatide vs. placebo or insulin on BP measurements in pooled data from six trials including 2,171 subjects studied for at least 6 months. RESULTS Overall, 6 months of exenatide treatment was associated with a significantly greater reduction in systolic BP (SBP) compared with placebo (least squares mean (s.e.): difference of -2.8 mm Hg (0.75); P = 0.0002) or insulin (difference of -3.7 mm Hg (0.85); P < 0.0001). No significant intergroup differences in diastolic BP (DBP) were observed. The majority of the intergroup difference was observed in subjects with SBP > or = 130 mm Hg (difference of -3.8 mm Hg (1.08) from placebo: P = 0.0004; difference of -4.0 mm Hg (1.01) from insulin; P < 0.0001). The largest intertreatment differences between exenatide and comparators were observed in subjects with SBP >/=150 mm Hg. Similar responses were observed in African-American subjects. A weak correlation between the amount of weight lost and reduction in SBP was found (r = 0.09, P = 0.002) for exenatide-treated subjects. CONCLUSIONS These results support the need for a prospective, randomized, controlled study of BP changes during exenatide treatment in patients with hypertension and type 2 diabetes.
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433
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Mudaliar S, Henry RR. Effects of incretin hormones on beta-cell mass and function, body weight, and hepatic and myocardial function. Am J Med 2010; 123:S19-27. [PMID: 20206728 DOI: 10.1016/j.amjmed.2009.12.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Type 2 diabetes mellitus is a chronic debilitating disease characterized by insulin resistance and progressive pancreatic dysfunction. Concomitant with declining pancreatic function and decreasing insulin production, there is a progressive increase in blood glucose levels. Hyperglycemia plays a major role in the development of the microvascular and macrovascular complications of diabetes. Traditional agents used for the treatment of type 2 diabetes are able to improve glycemia, but their use is often limited by treatment-associated side effects, including hypoglycemia, weight gain, and edema. Moreover, these agents do not have any sustained effect on beta-cell mass or function. The introduction of incretin hormone-based therapies represents a novel therapeutic strategy, because these drugs not only improve glycemia with minimal risk of hypoglycemia but also have other extraglycemic beneficial effects. In clinical studies, both exenatide (the first dipeptidyl peptidase-4-resistant glucagonlike peptide-1 receptor agonist approved by the US Food and Drug Administration [FDA]), and liraglutide (a long-acting incretin mimetic), improve beta-cell function and glycemia with minimal hypoglycemia. Both agents have trophic effects on beta-cell mass in animal studies. The use of these agents is also associated with reduced body weight and improvements in blood pressure, diabetic dyslipidemia, hepatic function, and myocardial function. These effects have the potential to reduce the burden of cardiovascular disease, which is a major cause of mortality in patients with diabetes.
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Affiliation(s)
- Sunder Mudaliar
- Section of Diabetes/Metabolism, VA San Diego Healthcare System, San Diego, California 92161, USA.
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434
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Russell-Jones D. Current developments in the treatment of diabetes: the incretin therapies. ACTA ACUST UNITED AC 2010. [DOI: 10.1177/1474651409357266] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The prevalence of type 2 diabetes in the UK has increased enormously over recent years and is closely associated with obesity and other risk factors for cardiovascular disease. The incretin system, which contributes significantly to the insulin response in healthy individuals, but is impaired in individuals with diabetes, offers a target for the development of agents that address many aspects of diabetes. These agents are broadly split into two categories — the glucagon-like polypeptide-1 (GLP-1) receptor agonists and the dipeptidyl peptidase-4 (DPP-4) inhibitors. The DPP-4 inhibitors sitagliptin and vildagliptin, along with the GLP-1 receptor agonists exenatide and liraglutide are currently approved for use and offer effective glycaemic control with a low risk of hypoglycaemia. GLP-1 receptor agonists may offer further benefits over both DPP-4 inhibitors and conventional therapies, such as reductions in body weight and blood pressure. Here we review the incretin system (with particular reference to GLP-1) and consider the development of these two classes of antidiabetic therapy, discussing the safety and efficacy of some of the latest available GLP-1 receptor agonists and DPP-4 inhibitors.
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Affiliation(s)
- David Russell-Jones
- Diabetes and Endocrinology, , Royal Surrey County Hospital, Egerton Road, Guildford GU2 7XX, UK,
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435
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Asmar M, Holst JJ. Glucagon-like peptide 1 and glucose-dependent insulinotropic polypeptide: new advances. Curr Opin Endocrinol Diabetes Obes 2010; 17:57-62. [PMID: 19881341 DOI: 10.1097/med.0b013e3283339051] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE OF REVIEW This article highlights recent advances in our understanding of glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) physiology and their various sites of action beyond the incretin effect. RECENT FINDINGS Both GLP-1 and GIP stimulate insulin secretion in a glucose-dependent manner and are thus classified as incretins. Beyond glucose-dependent insulin secretion, the peptides have common actions on islet beta cells, leading beta-cell proliferation and resistance to apoptosis. However, the action of GLP-1 and GIP is not limited to the islet cells; they have regulatory functions in many organs. Recent evidence has suggested that GLP-1 has important beneficial effects in the cardiovascular system and central nervous system. GIP may play a role in promoting energy storage in humans, enhances bone formation via stimulation of osteoblast proliferation and inhibition of apoptosis and may play a role in central nervous system function. SUMMARY These new findings suggest further application of these hormones for the treatment of conditions such as cardiovascular disease and obesity.
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Affiliation(s)
- Meena Asmar
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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436
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Gill A, Hoogwerf BJ, Burger J, Bruce S, Macconell L, Yan P, Braun D, Giaconia J, Malone J. Effect of exenatide on heart rate and blood pressure in subjects with type 2 diabetes mellitus: a double-blind, placebo-controlled, randomized pilot study. Cardiovasc Diabetol 2010; 9:6. [PMID: 20109208 PMCID: PMC2823663 DOI: 10.1186/1475-2840-9-6] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 01/28/2010] [Indexed: 12/25/2022] Open
Abstract
Background Cardiovascular effects of glucose-lowering agents are of increasing interest. Our aim was to assess the effects of the glucagon-like peptide-1 receptor agonist exenatide on heart rate (HR) and blood pressure (BP) in subjects with type 2 diabetes mellitus (T2DM). Methods In this double-blind, placebo-controlled trial, subjects with T2DM on metformin and/or a thiazolidinedione were randomized to receive exenatide (5 μg for 4 weeks followed by 10 μg) or placebo BID for 12 weeks. Heart rate and BP were assessed with 24-hour ambulatory BP monitoring. The primary measure was change from baseline in mean 24-hour HR. Results Fifty-four subjects (28 exenatide, 26 placebo) were randomized and comprised the intent-to-treat population. Baseline values (exenatide and placebo) were (mean ± SE) 74.4 ± 2.1 and 74.5 ± 1.9 beats/minute for HR, 126.4 ± 3.2 and 119.9 ± 2.8 mm Hg for systolic BP (SBP), and 75.2 ± 2.1 and 70.5 ± 2.0 mm Hg for diastolic BP (DBP). At 12 weeks, no significant change from baseline in 24-hour HR was observed with exenatide or placebo (LS mean ± SE, 2.1 ± 1.4 versus -0.7 ± 1.4 beats/minute, respectively; between treatments, p = 0.16). Exenatide therapy was associated with trends toward lower 24-hour, daytime, and nighttime SBP; changes in DBP were similar between groups. No changes in daytime or nighttime rate pressure product were observed. With exenatide, body weight decreased from baseline by -1.8 ± 0.4 kg (p < 0.0001; treatment difference -1.5 ± 0.6 kg, p < 0.05). The most frequently reported adverse event with exenatide was mild to moderate nausea. Conclusions Exenatide demonstrated no clinically meaningful effects on HR over 12 weeks of treatment in subjects with T2DM. The observed trends toward lower SBP with exenatide warrant future investigation. Trial registration NCT00516074
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Affiliation(s)
- Anne Gill
- Eli Lilly and Company, Indianapolis, USA
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437
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Grieve DJ, Cassidy RS, Green BD. Emerging cardiovascular actions of the incretin hormone glucagon-like peptide-1: potential therapeutic benefits beyond glycaemic control? Br J Pharmacol 2010; 157:1340-51. [PMID: 19681866 DOI: 10.1111/j.1476-5381.2009.00376.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1) is an incretin hormone secreted by the small intestine in response to nutrient ingestion. It has wide-ranging effects on glucose metabolism, including stimulation of insulin release, inhibition of glucagon secretion, reduction of gastric emptying and augmentation of satiety. Importantly, the insulinotropic actions of GLP-1 are uniquely dependent on ambient glucose concentrations, and it is this particular characteristic which has led to its recent emergence as a treatment for type 2 diabetes. Although the major physiological function of GLP-1 appears to be in relation to glycaemic control, there is growing evidence to suggest that it may also play an important role in the cardiovascular system. GLP-1 receptors (GLP-1Rs) are expressed in the heart and vasculature of both rodents and humans, and recent studies have demonstrated that GLP-1R agonists have wide-ranging cardiovascular actions, such as modulation of heart rate, blood pressure, vascular tone and myocardial contractility. Importantly, it appears that these agents may also have beneficial effects in the setting of cardiovascular disease (CVD). For example, GLP-1 has been found to exert cardioprotective actions in experimental models of dilated cardiomyopathy, hypertensive heart failure and myocardial infarction (MI). Preliminary clinical studies also indicate that GLP-1 infusion may improve cardiac contractile function in chronic heart failure patients with and without diabetes, and in MI patients after successful angioplasty. This review will discuss the current understanding of GLP-1 biology, examine its emerging cardiovascular actions in both health and disease and explore the potential use of GLP-1 as a novel treatment for CVD.
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Affiliation(s)
- David J Grieve
- Centre for Vision and Vascular Science, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, UK.
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438
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McIntosh CHS, Widenmaier S, Kim SJ. Pleiotropic actions of the incretin hormones. VITAMINS AND HORMONES 2010; 84:21-79. [PMID: 21094896 DOI: 10.1016/b978-0-12-381517-0.00002-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The insulin secretory response to a meal results largely from glucose stimulation of the pancreatic islets and both direct and indirect (autonomic) glucose-dependent stimulation by incretin hormones released from the gastrointestinal tract. Two incretins, Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), have so far been identified. Localization of the cognate G protein-coupled receptors for GIP and GLP-1 revealed that they are present in numerous tissues in addition to the endocrine pancreas, including the gastrointestinal, cardiovascular, central nervous and autonomic nervous systems (ANSs), adipose tissue, and bone. At these sites, the incretin hormones exert a range of pleiotropic effects, many of which contribute to the integration of processes involved in the regulation of food intake, and nutrient and mineral processing and storage. From detailed studies at the cellular and molecular level, it is also evident that both incretin hormones act via multiple signal transduction pathways that regulate both acute and long-term cell function. Here, we provide an overview of current knowledge relating to the physiological roles of GIP and GLP-1, with specific emphasis on their modes of action on islet hormone secretion, β-cell proliferation and survival, central and autonomic neuronal function, gastrointestinal motility, and glucose and lipid metabolism. However, it is emphasized that despite intensive research on the various body systems, in many cases there is uncertainty as to the pathways by which the incretins mediate their pleiotropic effects and only a rudimentary understanding of the underlying cellular mechanisms involved, and these are challenges for the future.
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Affiliation(s)
- Christopher H S McIntosh
- Department of Cellular & Physiological Sciences and the Diabetes Research Group, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
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439
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440
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Gallwitz B. Preclinical and Clinical Data on Extraglycemic Effects of GLP-1 Receptor Agonists. Rev Diabet Stud 2009; 6:247-59. [PMID: 20043037 DOI: 10.1900/rds.2009.6.247] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The diverse actions of the incretin hormone glucagon-like peptide (GLP)-1 include insulinotropic, beta-cell preservative, cardioprotective and vasodilatory effects. This spectrum makes GLP-1 an appealing therapeutic option for patients with type 2 diabetes. However, its rapid metabolism by the enzyme dipeptidyl peptidase (DPP)-4 renders it impractical. Incretin-based analogues have been developed to extend endogenous GLP-1 action (GLP-1 receptor agonists) and to hamper its degradation (DPP-4 inhibitors). Evidence suggests that GLP-1 receptor agonists and DPP-4 inhibitors have different pharmacodynamic and pharmacokinetic effects. For example, GLP-1 receptor agonists deliver supraphysiologic levels of GLP-1 analogues designed to resist inactivation by DPP-4, whereas DPP-4 inhibition conserves native GLP-1 resulting in concentrations within the physiologic range. Furthermore, GLP-1 receptor agonists induce glucose-dependent insulin secretion, beta-cell protection, and other extraglycemic benefits such as weight loss and improvement in markers of cardiovascular risk. In contrast, DPP-4 inhibitors are weight neutral and have modest effects on glucose control. DPP-4 inhibition is dependent on the availability of endogenous GLP-1, which appears to be adversely affected by type 2 diabetes and its progression. Therefore, DPP-4 inhibitors may be better suited for patients with mild hyperglycemia without comorbidities. This review examines the present understanding of the pancreatic effects of endogenous GLP-1, and the extrapancreatic actions it exerts on human bodily systems. Also, it analyzes available preclinical and clinical data on incretin therapies with respect to glycemia, lipids, blood pressure, and weight.
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Affiliation(s)
- Baptist Gallwitz
- Department of Medicine IV, Universitätsklinikum Tübingen, Otfried-Müller-Str. 10, 72076 Tübingen, Germany
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441
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Bode B, Amin A. Incretin-based therapies: review of the outpatient literature with implications for use in the hospital and after discharge. Hosp Pract (1995) 2009; 37:7-21. [PMID: 20720383 DOI: 10.3810/hp.2009.12.249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A large percentage of critically ill adult inpatients have type 2 diabetes, which may be undiagnosed or uncontrolled during hospitalization. Hyperglycemia complicates the therapeutic management of inpatients and leads to adverse outcomes, and intensive glycemic control with insulin reduces morbidity and mortality. Insulin therapy, however, is labor-intensive and time-consuming. More important, long-standing protocols such as the sliding scale do not provide adequate glucose control. Although more research is needed to determine the best methods for treating hyperglycemia in-hospital, the importance of achieving better glycemic control while reducing the risk of hypoglycemia has been demonstrated. Post-discharge diabetes care is equally important, as it is essential in improving long-term outcomes after a hospital stay. Hospital care providers can play an important role in effective antihyperglycemic regimens in patients with diabetes prior to discharge. Post-discharge management is a formidable challenge because of the availability of an array of oral antidiabetes agents, including metformin, sulfonylureas, and thiazolidinediones, each with distinct therapeutic and adverse event profiles. Incretin-based therapies offer a potentially useful option for post-discharge therapy, and possibly for inpatient diabetes treatment. Incretins are effective, safe, and well-tolerated; they are easier for patients to use compared with insulin injections (eg, continual glucose monitoring is not required); and they may provide long-term improvement of cardiovascular parameters and beta-cell function. This review examines the challenges to achieving glycemic control in the hospital setting and summarizes clinical data on the efficacy and safety of incretin-based therapies in their use in the hospital and after discharge.
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Affiliation(s)
- Bruce Bode
- Atlanta Diabetes Associates, Atlanta, GA 30309, USA.
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442
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Abstract
Cardiovascular (CV) disease is the major cause of mortality and morbidity in individuals with diabetes. Individuals with diabetes often have a variety of factors such as hyperglycaemia, dyslipidaemia, hypertension, insulin resistance and obesity, which increase their risks of endothelial dysfunction and CV disease. The incretin hormones, such as glucagon-like peptide-1 (GLP-1), induce the glucose-dependent secretion of insulin, improve beta-cell function and induce slowing of gastric emptying and feelings of satiety - which result in reduced food intake and weight loss. Therapeutic treatments targeting the incretin system, such as GLP-1 receptor agonists, offer the potential to address beta-cell dysfunction (one the underlying pathogenic mechanisms of type 2 diabetes), as well as the resulting hyperglycaemia. Initial evidence now suggests that incretins could have beneficial effects on endothelial function and the CV system through both indirect effects on the reduction of hyperglycaemia and direct effects mediated through GLP-1 receptor-dependent and -independent mechanisms. If these initial findings are confirmed in larger clinical trials, GLP-1 receptor antagonists could help to address the major CV risks faced by patients with diabetes.
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Affiliation(s)
- A Sjöholm
- Department of Clinical Science, Division of Internal Medicine, Unit for Diabetes Research, Karolinska Institutet, Stockholm, Sweden.
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443
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Janosz KEN, Zalesin KC, Miller WM, McCullough PA. Treating type 2 diabetes: incretin mimetics and enhancers. Ther Adv Cardiovasc Dis 2009; 3:387-95. [PMID: 19808944 DOI: 10.1177/1753944709341377] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
As a consequence of excess abdominal adiposity and genetic predisposition, type 2 diabetes is a progressive disease, often diagnosed after metabolic dysfunction has taken hold of multiple organ systems. Insulin deficiency, insulin resistance and impaired glucose homeostasis resulting from beta-cell dysfunction characterize the disease. Current treatment goals are often unmet due to insufficient treatment modalities. Even when combined, these treatment modalities are frequently limited by safety, tolerability, weight gain, edema and gastrointestinal intolerance. Recently, new therapeutic classes have become available for treatment. This review will examine the new therapeutic classes of incretin mimetics and enhancers in the treatment of type 2 diabetes.
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444
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445
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Verspohl E. Novel therapeutics for type 2 diabetes: Incretin hormone mimetics (glucagon-like peptide-1 receptor agonists) and dipeptidyl peptidase-4 inhibitors. Pharmacol Ther 2009; 124:113-38. [DOI: 10.1016/j.pharmthera.2009.06.002] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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446
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Rizzo M, Rizvi AA, Spinas GA, Rini GB, Berneis K. Glucose lowering and anti-atherogenic effects of incretin-based therapies: GLP-1 analogues and DPP-4-inhibitors. Expert Opin Investig Drugs 2009; 18:1495-503. [DOI: 10.1517/14728220903241633] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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447
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Giugliano D, Standl E, Vilsbøll T, Betteridge J, Bonadonna R, Campbell IW, Schernthaner GH, Staels B, Trichopoulou A, Farinaro E. Is the current therapeutic armamentarium in diabetes enough to control the epidemic and its consequences? What are the current shortcomings? Acta Diabetol 2009; 46:173-81. [PMID: 19543848 DOI: 10.1007/s00592-009-0134-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Accepted: 05/07/2009] [Indexed: 01/01/2023]
Abstract
The prevalence of diabetes is expected to rise together with an increase in morbidity and a reduction in life expectancy. A leading cause of death is cardiovascular disease, and hypertension and diabetes are additive risk factors for this complication. Selected treatment options should neither increase cardiovascular risk in patients with diabetes, nor increase risk of hyperglycaemia in patients with hypertension. The efficacy of present antihyperglycaemic agents is limited and new therapies, such as incretin-targeted agents, are under development. Even though most patients do not achieve glycated haemoglobin targets, trial data show that such interventions reduce the incidence of macrovascular events; however, intensive lowering may be detrimental in patients with existing cardiovascular disease. Currently available oral drugs do not address the key driver of type 2 diabetes--loss of functional beta-cell mass. In the future, new oral treatments must improve this, whilst providing durable blood glucose control and long-term tolerability.
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Affiliation(s)
- Dario Giugliano
- Division of Metabolic Diseases, Center of Excellence for Cardiovascular Diseases, Second University of Naples, Piazza Miraglia, 80138, Naples, Italy.
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448
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Dozier KC, Cureton EL, Kwan RO, Curran B, Sadjadi J, Victorino GP. Glucagon-like peptide-1 protects mesenteric endothelium from injury during inflammation. Peptides 2009; 30:1735-41. [PMID: 19560500 PMCID: PMC2954434 DOI: 10.1016/j.peptides.2009.06.019] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 06/16/2009] [Accepted: 06/17/2009] [Indexed: 12/29/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) is a proglucagon-derived hormone with cellular protective actions. We hypothesized that GLP-1 would protect the endothelium from injury during inflammation. Our aims were to determine the: (1) effect of GLP-1 on basal microvascular permeability, (2) effect of GLP-1 on increased microvascular permeability induced by lipopolysaccaride (LPS), (3) involvement of the GLP-1 receptor in GLP-1 activity, and (4) involvement of the cAMP/PKA pathway in GLP-1 activity. Microvascular permeability (L(p)) of rat mesenteric post-capillary venules was measured in vivo. First, the effect of GLP-1 on basal L(p) was measured. Second, after systemic LPS injection, L(p) was measured after subsequent perfusion with GLP-1. Thirdly, L(p) was measured after LPS injection and perfusion with GLP-1+GLP-1 receptor antagonist. Lastly, L(p) was measured after LPS injection and perfusion with GLP-1+inhibitors of the cAMP/PKA pathway. Results are presented as mean area under the curve (AUC)+/-SEM. GLP-1 had no effect on L(p) (AUC: baseline=27+/-1.4, GLP-1=1+/-0.4, p=0.08). LPS increased L(p) two-fold (AUC: LPS=54+/-1.7, p<0.0001). GLP-1 reduced the LPS increase in L(p) by 75% (AUC: LPS+GLP-1=34+/-1.5, p<0.0001). GLP-1 antagonism reduced the effects of GLP-1 by 60% (AUC: LPS+GLP-1+antagonist=46+/-2.0, p<0.001). The cAMP synthesis inhibitor reduced the effects of GLP-1 by 60% (AUC: LPS+GLP-1+cAMP inhibitor=46+/-1.5, p<0.0001). The PKA inhibitor reduced the effects of GLP-1 by 100% (AUC: LPS+GLP-1+PKA inhibitor=56+/-1.5, p<0.0001). GLP-1 attenuates the increase in microvascular permeability induced by LPS. GLP-1 may protect the endothelium during inflammation, thus decreasing third-space fluid loss.
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Affiliation(s)
- Kristopher C Dozier
- Department of Surgery, University of California, San Francisco-East Bay, Alameda County Medical Center, Oakland, CA, USA
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449
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Nathanson D, Erdogdu O, Pernow J, Zhang Q, Nyström T. Endothelial dysfunction induced by triglycerides is not restored by exenatide in rat conduit arteries ex vivo. ACTA ACUST UNITED AC 2009; 157:8-13. [PMID: 19595708 DOI: 10.1016/j.regpep.2009.07.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 05/14/2009] [Accepted: 07/02/2009] [Indexed: 01/04/2023]
Abstract
Exenatide (synthetic exendin-4) is a stable analogue of glucagon-like peptide 1 (GLP-1) and has recently been approved for clinical use against type 2 diabetes. Exenatide is believed to exert its effects via the GLP-1 receptor with almost the same potency as GLP-1 in terms of lowering blood glucose. Short term exenatide treatment normalizes the altered vascular tone in type 2 diabetic rats, probably due to the reduction in glycemia. The aim of this study was to investigate whether exenatide directly protects against triglyceride-induced endothelial dysfunction in rat femoral arterial rings ex vivo. Short term pre-incubation with Intralipid (0.5 and 2%) was found to dose-dependently induce endothelial dysfunction, in that it elicited a significant reduction in ACh-induced vasorelaxation by 29% and 35%, respectively. Paradoxically, this occurred with a concomitant increase in endothelial nitric oxide synthase (eNOS) activity. No such reduction in vasorelaxation by Intralipid was seen in response to the NO donor sodium nitroprusside (SNP), revealing an endothelium-dependent vascular dysfunction by Intralipid. However, exenatide did not protect against Intralipid-induced endothelial dysfunction. More surprisingly, the maximum vasorelaxation induced by exenatide (without Intralipid was only 3+/-2%, compared to the 23+/-4%, 38+/-4%, 79+/-3% and 97+/-4% relaxations induced by GLP-1, GLP-1 (9-36), ACh and SNP, respectively. This unexpected finding prompted us to ascertain that the exenatide preparation was biologically active, and both exenatide (10(-11) mol/l) and GLP-1 (10(-9) mol/l) significantly increased insulin secretion in pancreatic beta-cells from ob/ob mice in vitro. In conclusion, exenatide could neither confer any acute protective effects against triglyceride-induced endothelial dysfunction nor exert any significant vasorelaxant actions in this model of rat conduit arteries ex vivo.
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Affiliation(s)
- David Nathanson
- Karolinska Institutet, Department of Internal Medicine, South Hospital, Sweden.
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450
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Zinman B, Gerich J, Buse JB, Lewin A, Schwartz S, Raskin P, Hale PM, Zdravkovic M, Blonde L. Efficacy and safety of the human glucagon-like peptide-1 analog liraglutide in combination with metformin and thiazolidinedione in patients with type 2 diabetes (LEAD-4 Met+TZD). Diabetes Care 2009; 32:1224-30. [PMID: 19289857 PMCID: PMC2699702 DOI: 10.2337/dc08-2124] [Citation(s) in RCA: 676] [Impact Index Per Article: 45.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To determine the efficacy and safety of liraglutide (a glucagon-like peptide-1 receptor agonist) when added to metformin and rosiglitazone in type 2 diabetes. RESEARCH DESIGN AND METHODS This 26-week, double-blind, placebo-controlled, parallel-group trial randomized 533 subjects (1:1:1) to once-daily liraglutide (1.2 or 1.8 mg) or liraglutide placebo in combination with metformin (1 g twice daily) and rosiglitazone (4 mg twice daily). Subjects had type 2 diabetes, A1C 7-11% (previous oral antidiabetes drug [OAD] monotherapy >or=3 months) or 7-10% (previous OAD combination therapy >or=3 months), and BMI <or=45 kg/m(2). RESULTS Mean A1C values decreased significantly more in the liraglutide groups versus placebo (mean +/- SE -1.5 +/- 0.1% for both 1.2 and 1.8 mg liraglutide and -0.5 +/- 0.1% for placebo). Fasting plasma glucose decreased by 40, 44, and 8 mg/dl for 1.2 and 1.8 mg and placebo, respectively, and 90-min postprandial glucose decreased by 47, 49, and 14 mg/dl, respectively (P < 0.001 for all liraglutide groups vs. placebo). Dose-dependent weight loss occurred with 1.2 and 1.8 mg liraglutide (1.0 +/- 0.3 and 2.0 +/- 0.3 kg, respectively) (P < 0.0001) compared with weight gain with placebo (0.6 +/- 0.3 kg). Systolic blood pressure decreased by 6.7, 5.6, and 1.1 mmHg with 1.2 and 1.8 mg liraglutide and placebo, respectively. Significant increases in C-peptide and homeostasis model assessment of beta-cell function and significant decreases in the proinsulin-to-insulin ratio occurred with liraglutide versus placebo. Minor hypoglycemia occurred more frequently with liraglutide, but there was no major hypoglycemia. Gastrointestinal adverse events were more common with liraglutide, but most occurred early and were transient. CONCLUSIONS Liraglutide combined with metformin and a thiazolidinedione is a well-tolerated combination therapy for type 2 diabetes, providing significant improvements in glycemic control.
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Affiliation(s)
- Bernard Zinman
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada,
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