glucagon-like-peptide-1 and Neointima

Recently, incretin therapy has attracted increasing attention because of its potential use in tissue-protective therapy. Neuron-derived orphan receptor 1 (NOR1) is a nuclear orphan receptor that regulates vascular smooth muscle cell (VSMC) proliferation. In the present study, we investigated the vascular-protective effect of Exendin-4 (Ex-4), a glucagon-like peptide-1 receptor agonist, by inhibiting NOR1 expression in VSMCs.. We classified 7-week-old male 129X1/SvJ mice into control group and Ex-4 low- and high-dose-treated groups fed normal or high-fat diets, respectively. Endothelial denudation injuries were induced in the femoral artery at 8 weeks of age, followed by the evaluation of neointima formation at 12 weeks of age. To evaluate VSMC proliferation, bromodeoxyuridine incorporation assay and cell cycle distribution analysis were performed. NOR1 and cell cycle regulators were detected using immunohistochemistry, western blotting, quantitative reverse-transcription polymerase chain reaction, and luciferase assays.. Ex-4 treatment reduced vascular injury-induced neointima formation compared with controls. In terms of VSMCs occupying the neointima area, VSMC numbers and NOR1-expressing proliferative cells were significantly decreased by Ex-4 in a dose-dependent manner in both diabetic and non-diabetic mice. In vitro experiments using primary cultured VSMCs revealed that Ex-4 attenuated NOR1 expression by reducing extracellular signal-regulated kinase-mitogen-activated protein kinase and cAMP-responsive element-binding protein phosphorylations. Furthermore, in the cell cycle distribution analysis, serum-induced G1-S phase entry was significantly attenuated by Ex-4 treatment of VSMCs by inhibiting the induction of S-phase kinase-associated protein 2.. Ex-4 attenuates neointima formation after vascular injury and VSMC proliferation possibly by inhibiting NOR1 expression.

Topics: Animals; Cells, Cultured; DNA-Binding Proteins; Exenatide; Glucagon-Like Peptide 1; Hypoglycemic Agents; Male; Mice; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Neointima; Nerve Tissue Proteins; Receptors, Steroid; Receptors, Thyroid Hormone

Hyperglycaemia causes endothelial dysfunction, which is the initial process in the development of diabetic vascular complications. Upon injury, endothelial cells undergo an endothelial-to-mesenchymal transition (EndMT), lose their specific marker, and gain mesenchymal phenotypes. This study investigated the effect of liraglutide, a glucagon-like peptide 1 (GLP-1) receptor agonist, on EndMT inhibition and neointima formation in diabetic mice induced by streptozotocin. The diabetic mice with a wire-induced vascular injury in the right carotid artery were treated with or without liraglutide for four weeks. The degree of neointima formation and re-endothelialisation was evaluated by histological assessments. Endothelial fate tracing revealed that endothelium-derived cells contribute to neointima formation through EndMT in vivo. In the diabetic mouse model, liraglutide attenuated wire injury-induced neointima formation and accelerated re-endothelialisation. In vitro, a high glucose condition (30 mmol/L) triggered morphological changes and mesenchymal marker expression in human umbilical vein endothelial cells (HUVECs), which were attenuated by liraglutide or Activin receptor-like 5 (ALK5) inhibitor SB431542. The inhibition of AMP-activated protein kinase (AMPK) signaling by Compound C diminished the liraglutide-mediated inhibitory effect on EndMT. Collectively, liraglutide was found to attenuate neointima formation in diabetic mice partially through EndMT inhibition, extending the potential therapeutic role of liraglutide.

Topics: Adenylate Kinase; Animals; Arteries; Biomarkers; Diabetes Mellitus, Experimental; Endothelium; Glucagon-Like Peptide 1; Glucose; Human Umbilical Vein Endothelial Cells; Humans; Interleukin-1beta; Liraglutide; Mesoderm; Mice, Inbred C57BL; Mice, Transgenic; Neointima; RNA, Messenger; Signal Transduction; Smad2 Protein; Snail Family Transcription Factors; Streptozocin

Enhancement of glucagon-like peptide-1 (GLP-1) reduces glucose levels and preserves pancreatic β-cell function, but its effect against restenosis is unknown.. We investigated the effect of subcutaneous injection of exenatide or local delivery of a recombinant adenovirus expressing GLP-1 (rAd-GLP-1) into carotid artery, in reducing the occurrence of restenosis following balloon injury. As a control, we inserted β-galactosidase cDNA in the same vector (rAd-βGAL). Otsuka Long-Evans Tokushima rats were assigned to three groups (n = 12 each): (1) normal saline plus rAd-βGAL delivery (NS + rAd-βGAL), (2) exenatide plus rAd-βGAL delivery (Exenatide + rAd-βGAL), and (3) normal saline plus rAd-GLP-1 delivery (NS + rAd-GLP-1). Normal saline or exenatide were administered subcutaneously from 1 week before to 2 weeks after carotid injury. After 3 weeks, the NS + rAd-βGAL group showed the highest intima-media ratio (IMR; 3.73 ± 0.90), the exenatide + rAd-βGAL treatment was the next highest (2.80 ± 0.51), and NS + rAd-GLP-1 treatment showed the lowest IMR (1.58 ± 0.48, P < 0.05 vs. others). The proliferation and migration of vascular smooth muscle cells and monocyte adhesion were decreased significantly after rAd-GLP-1 treatment, showing the same overall patterns as the IMR. In injured vessels, the apoptosis was greater and MMP2 expression was less in the NS + rAd-GLP-1 than in the exenatide or rAd-βGAL groups. In vitro expressions of matrix metalloproteinases-2 and monocyte chemoattractant protein-1 and nuclear factor-kappa-B-p65 translocation were decreased more in the NS + rAd-GLP-1 group than in the other two groups (all P < 0.05).. Direct GLP-1 overexpression showed better protection against restenosis after balloon injury via suppression of vascular smooth muscle cell migration, increased apoptosis, and decreased inflammatory processes than systemic exenatide treatment. This has potential therapeutic implications for treating macrovascular complications in diabetes.

Topics: Adenoviridae; Animals; Apoptosis; Carotid Artery Injuries; Carotid Artery, External; Cell Adhesion; Cell Movement; Cell Proliferation; Cells, Cultured; Coronary Stenosis; Diabetes Mellitus; Disease Models, Animal; Exenatide; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Glucagon-Like Peptide 1; Human Umbilical Vein Endothelial Cells; Hypoglycemic Agents; Incretins; Male; Matrix Metalloproteinase 2; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Neointima; Peptides; Rats, Inbred OLETF; Transcription Factor RelA; Transfection; Venoms

Dipeptidyl peptidase 4 inhibitors are widely used in patients with type 2 diabetes mellitus to accomplish glycemic control through an increase in the blood glucagon-like peptide 1 (GLP-1) concentration. These agents also inhibit vascular inflammation (eg, in atherosclerosis). This study was undertaken to determine whether and how vildagliptin (a potent dipeptidyl peptidase 4 inhibitor) might reduce intimal hyperplasia in vein grafts.. Twelve rabbits were randomly divided into two groups; one group received vildagliptin orally (10 mg/kg/d; n = 6), whereas the control group (n = 6) did not. Vildagliptin administration was started 7 days before rabbits underwent interposition reversed autologous jugular vein grafting and ended at graft harvesting (28 days after the operation). Histochemical changes in the vascular wall were examined, as were changes in the acetylcholine-induced effects on the endothelial Ca(2+) concentration ([Ca(2+)]i) and endothelium-dependent relaxation.. Under fasting conditions, vildagliptin increased the plasma GLP-1 concentration, without affecting plasma glucose or insulin. Acetylcholine induced endothelium-dependent relaxation only in the vildagliptin group, and this was blocked by the nitric oxide synthase inhibitor N(ω)-nitro-l-arginine. Acetylcholine did not modify the endothelial [Ca(2+)]i in either the control or vildagliptin group. Intimal hyperplasia was significantly less in the vildagliptin group (0.11 ± 0.02 mm, n = 5) than in the controls (0.31 ± 0.06 mm, n = 4; P < .01).. Vildagliptin increased the plasma GLP-1 concentration. It also enhanced acetylcholine-induced [Ca(2+)]i-independent endothelial nitric oxide release and reduced vein graft intimal hyperplasia, independently of any glycemic control action.

Topics: Adamantane; Administration, Oral; Animals; Autografts; Calcium; Calcium Signaling; Dipeptidyl Peptidase 4; Dipeptidyl-Peptidase IV Inhibitors; Disease Models, Animal; Dose-Response Relationship, Drug; Glucagon-Like Peptide 1; Hyperplasia; Jugular Veins; Male; Neointima; Nitric Oxide; Nitric Oxide Synthase; Nitriles; Pyrrolidines; Time Factors; Vasodilation; Vasodilator Agents; Vildagliptin

The results of recent studies suggest that dipeptidyl-peptidase-4 inhibitors have antiatherogenic effects. However, whether or not dipeptidyl-peptidase-4 inhibitors could suppress arterial inflammation and intimal hyperplasia after injury remains undetermined. The present study aims to clarify the anti-inflammatory effects of the dipeptidyl-peptidase-4 inhibitor, alogliptin (AGP), on the arteries of atherogenic low-density lipoprotein receptor-deficient (LKO) mice.. We compared intimal hyperplasia in LKO mice 2 weeks after femoral artery injury using an external vascular cuff model. All mice received oral injection of AGP (20 mg/kg per day) or normal saline (control) once daily for 14 days. Fasting blood sugar levels, serum cholesterol levels, or blood pressure did not significantly differ between the 2 groups. Plasma levels of active glucagon-like peptide-1 were higher in the AGP than in the control LKO mice (22.2±1.9 versus 15.6±0.9 pg/mL; P<0.05). Compared with saline, AGP significantly reduced intimal hyperplasia (1087±127 versus 1896±140 μm(2); P<0.001) as well as the intima/media ratio (0.08±0.01 versus 0.16±0.02; P<0.001). Immunostaining showed that AGP reduced proliferating cells (proliferating cell nuclear antigen-positive nuclei; P<0.001), percent smooth-muscle cell area (α-SMA-positive cells; P<0.001), inflammatory cells infiltration (lymphocyte antigen 6 complex-positive cells; P<0.05), tumor necrosis factor-α expression (P<0.05), and percent phospho-NF-κB-positive cell compared with saline. Levels of tumor necrosis factor -α (0.5-fold P<0.05), monocyte chemoattractant protein 1 (0.3-fold P<0.01), and interleukin-1β (0.2-fold P<0.05) mRNA were lower in the injured arteries of the AGP than in the control group.. AGP appeared to suppress neointimal formation by inhibiting inflammation, independently of its effects on glucose or cholesterol metabolism in atherogenic LKO mice.

Topics: Actins; Animals; Anti-Inflammatory Agents; Arteritis; Atherosclerosis; Biomarkers; Blood Glucose; Cell Proliferation; Chemokine CCL2; Cholesterol; Dipeptidyl Peptidase 4; Dipeptidyl-Peptidase IV Inhibitors; Disease Models, Animal; Femoral Artery; Glucagon-Like Peptide 1; Inflammation Mediators; Interleukin-1beta; Male; Mice, Knockout; Neointima; NF-kappa B; Phosphorylation; Piperidines; Proliferating Cell Nuclear Antigen; Receptors, LDL; Tumor Necrosis Factor-alpha; Uracil; Vascular System Injuries

Recently, glucagon-like peptide-1 (GLP-1)-based therapy, including dipeptidyl peptidase-4 (DPP-4) inhibitors and GLP-1 receptor agonists, has emerged as one of the most popular anti-diabetic therapies. Furthermore, GLP-1-based therapy has attracted increased attention not only for its glucose-lowering ability, but also for its potential as a tissue-protective therapy. In this study, we investigated the vascular-protective effect of the DPP-4 inhibitor, linagliptin, using vascular smooth muscle cells (VSMCs).. Six-week-old male C57BL/6 mice were divided into control (n =19) and linagliptin (3 mg/kg/day, n =20) treated groups. Endothelial denudation injuries were induced in the femoral artery at 8 weeks of age, followed by evaluation of neointima formation at 12 weeks. To evaluate cell proliferation of rat aortic smooth muscle cells, a bromodeoxyuridine (BrdU) incorporation assay was performed.. Linagliptin treatment reduced vascular injury-induced neointima formation, compared with controls (p <0.05). In these non-diabetic mice, the body weight and blood glucose levels did not change after treatment with linagliptin. Linagliptin caused an approximately 1.5-fold increase in serum active GLP-1 concentration, compared with controls. In addition, the vascular injury-induced increase in the oxidative stress marker, urinary 8-OHdG, was attenuated by linagliptin treatment, though this attenuation was not statistically significant (p =0.064). Moreover, linagliptin did not change the serum stromal cell-derived factor-1α (SDF-1α) or the serum platelet-derived growth factor (PDGF) concentration. However, linagliptin significantly reduced in vitro VSMC proliferation.. Linagliptin attenuates neointima formation after vascular injury and VSMC proliferation beyond the glucose-lowering effect.

Topics: Animals; Blood Glucose; Diabetes Mellitus, Experimental; Dipeptidyl Peptidase 4; Dipeptidyl-Peptidase IV Inhibitors; Glucagon-Like Peptide 1; Hypoglycemic Agents; Linagliptin; Male; Mice, Inbred C57BL; Neointima; Purines; Quinazolines; Vascular System Injuries

Glucagon-like peptide-1 is a hormone secreted by L cells of the small intestine and stimulates glucose-dependent insulin response. Glucagon-like peptide-1 receptor agonists such as exendin-4 are currently used in type 2 diabetes, and considered to have beneficial effects on the cardiovascular system. To further elucidate the effect of glucagon-like peptide-1 receptor agonists on cardiovascular diseases, we investigated the effects of exendin-4 on intimal thickening after endothelial injury. Under continuous infusion of exendin-4 at 24 nmol/kg/day, C57BL/6 mice were subjected to endothelial denudation injury of the femoral artery. Treatment of mice with exendin-4 reduced neointimal formation at 4weeks after arterial injury without altering body weight or various metabolic parameters. In addition, in vitro studies of isolated murine, rat and human aortic vascular smooth muscle cells showed the expression of GLP-1 receptor. The addition of 10nM exendin-4 to cultured smooth muscle cells significantly reduced their proliferation induced by platelet-derived growth factor. Our results suggested that exendin-4 reduced intimal thickening after vascular injury at least in part by the suppression of platelet-derived growth factor-induced smooth muscle cells proliferation.

Topics: Animals; Body Weight; Cell Proliferation; Cells, Cultured; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Glucose; Humans; Mice; Mice, Inbred C57BL; Myocytes, Smooth Muscle; Neointima; Peptides; Rats; Receptors, Glucagon; Signal Transduction; Tunica Intima; Vascular System Injuries; Venoms