exenatide and Diabetic-Retinopathy

Recent trials provide conflicting results on the association between glucagon-like peptide 1 receptor agonists (GLP-1RA) and diabetic retinopathy (DR). The aim of the AngioSafe type 2 diabetes (T2D) study was to determine the role of GLP-1RA in angiogenesis using clinical and preclinical models.. We performed two studies in humans. In study 1, we investigated the effect of GLP-1RA exposure from T2D diagnosis on the severity of DR, as diagnosed with retinal imaging (fundus photography). In study 2, a randomized 4-week trial, we assessed the effect of liraglutide on circulating hematopoietic progenitor cells (HPCs), and angio-miRNAs.We then studied the experimental effect of Exendin-4, on key steps of angiogenesis: in vitro on human endothelial cell proliferation, survival and three-dimensional vascular morphogenesis; and in vivo on ischemia-induced neovascularization of the retina in mice.. In the cohort of 3154 T2D patients, 10% displayed severe DR. In multivariate analysis, sex, disease duration, glycated hemoglobin (HbA1c), micro- and macroangiopathy, insulin therapy and hypertension remained strongly associated with severe DR, while no association was found with GLP-1RA exposure (o 1.139 [0.800-1.622], P = .47). We further showed no effect of liraglutide on HPCs, and angio-miRNAs. In vitro, we demonstrated that exendin-4 had no effect on proliferation and survival of human endothelial cells, no effect on total length and number of capillaries. Finally, in vivo, we showed that exendin-4 did not exert any negative effect on retinal neovascularization.. The AngioSafe T2D studies provide experimental and clinical data confirming no effect of GLP-1RA on angiogenesis and no association between GLP-1 exposure and severe DR.

Topics: Aged; Animals; Biomarkers; Blood Glucose; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Endothelial Cells; Exenatide; Female; Follow-Up Studies; Glucagon-Like Peptide-1 Receptor; Humans; Hypoglycemic Agents; Male; Mice; Middle Aged; Morphogenesis; Neovascularization, Pathologic; Prognosis; Retina

Activation of p. Adult human retinal pigment epithelial-19 cells were cultured under low (5 µM) or high glucose (100 µM) conditions in the presence or absence of Exendin-4 and with or without pre-incubation with Exendin-9-39, a glucagon-like peptide-1 receptor antagonist.. In a dose-dependent manner, Exendin-4 inhibited high glucose-induced cell death and decreased levels of reactive oxygen species, lactate dehydrogenase release, and single single-stranded DNA. At the most effective concentration (100 µM), Exendin-4 reduced mitochondrial levels of phospho-p. Exendin-4 protects against high glucose-induced adult human retinal pigment epithelial-19 cell damage by increasing antioxidants, downregulating NADPH, and inhibiting mitochondria-mediated apoptosis, effects that are associated with the inhibition of c-Jun N-terminal kinase and downregulation of protein kinase-β and p

Topics: Antioxidants; Blood Glucose; Cell Line; Diabetic Retinopathy; Dose-Response Relationship, Drug; Epithelial Cells; Exenatide; Gene Expression Regulation; Humans; Oxidative Stress; Reactive Oxygen Species; Retinal Pigment Epithelium; Src Homology 2 Domain-Containing, Transforming Protein 1

Retinal neurodegeneration is an early event in the pathogenesis of diabetic retinopathy (DR). Since glucagon-like peptide 1 (GLP-1) exerts neuroprotective effects in the central nervous system and the retina is ontogenically a brain-derived tissue, the aims of the current study were as follows: 1) to examine the expression and content of GLP-1 receptor (GLP-1R) in human and db/db mice retinas; 2) to determine the retinal neuroprotective effects of systemic and topical administration (eye drops) of GLP-1R agonists in db/db mice; and 3) to examine the underlying neuroprotective mechanisms. We have found abundant expression of GLP-1R in the human retina and retinas from db/db mice. Moreover, we have demonstrated that systemic administration of a GLP-1R agonist (liraglutide) prevents retinal neurodegeneration (glial activation, neural apoptosis, and electroretinographical abnormalities). This effect can be attributed to a significant reduction of extracellular glutamate and an increase of prosurvival signaling pathways. We have found a similar neuroprotective effect using topical administration of native GLP-1 and several GLP-1R agonists (liraglutide, lixisenatide, and exenatide). Notably, this neuroprotective action was observed without any reduction in blood glucose levels. These results suggest that GLP-1R activation itself prevents retinal neurodegeneration. Our results should open up a new approach in the treatment of the early stages of DR.

Topics: Administration, Ophthalmic; Aged; Animals; Apoptosis; Blotting, Western; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Electroretinography; Exenatide; Female; Glial Fibrillary Acidic Protein; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Humans; Immunohistochemistry; Liraglutide; Male; Mice; Middle Aged; Neuroprotective Agents; Peptides; Real-Time Polymerase Chain Reaction; Retina; Retinal Neurons; Venoms

This study was aimed to further investigate the possible mechanisms by which the glucagon like peptide 1 analogue, exendin-4 (EX4), protects rat retinal cells at the early stage of diabetes. EX4 was injected intravitreally into normal and early-stage streptozotocin-diabetic rats. Cell death, reactive oxygen species (ROS), and electroretinogram (ERG) were measured. Sirtuin (Sirt) mRNA and protein were analyzed. In retinas of diabetic rats 1 month after diabetes onset, cell death and ROS level increased significantly, and the b-wave amplitudes and OPs were significantly reduced. Four days after intravitreal EX4 treatment, retinal cell death and ROS level in retinas reduced significantly, and visual function was recovered. In the retinas of early-stage diabetic rats, the expressions of Sirt1 and Sirt3 were also found to be significantly decreased, and both were back to normal levels after intravitreal injection of EX4. In R28 cells, hydrogen peroxide (H2O2) treatment increased ROS and cell death and decreased Sirt1 and Sirt3. With the addition of EX4 into the culture system, the expressions of Sirt1 and Sirt3 were increased, and the H2O2-induced ROS and cell death were significantly reduced. These results confirm a mechanism for EX4 to protect retinal cells from diabetic damage and oxidative injury. EX4 reduces retinal cell death and ROS generation by upregulating Sirt1 and Sirt3 expressions in the retina of early-stage diabetic rats as well as in H2O2-treated R28 cells.

Topics: Animals; Cell Death; Cells, Cultured; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Electroretinography; Exenatide; Gene Expression Regulation; Glucagon-Like Peptide 1; Hypoglycemic Agents; Immunoblotting; In Situ Nick-End Labeling; Male; Oxidative Stress; Peptides; Rats; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; Retinal Ganglion Cells; RNA, Messenger; Sirtuin 1; Sirtuins; Time Factors; Venoms

The aim of this study is to report a case of complete regression of diabetic macular edema after subcutaneous injection of exenatide in a patient with type 2 diabetes mellitus. This study is an interventional case report. Blood investigations, complete ophthalmic examinations and optical coherence tomography were performed. A 55-year-old female affected by poorly controlled type 2 diabetes mellitus presented with visual impairment due to macular edema in the right eye. The left eye showed mild edema without visual loss. Best-corrected visual acuity (BCVA) was 20/80 and 20/20, respectively. The patient was encouraged to improve metabolic control, and the antidiabetic therapy was modified combining exenatide 10 μg subcutaneously twice daily to her regimen of oral metformin. The patient did not receive any ocular treatment. A complete tomographic resolution of macular edema was observed after 1 month and BCVA improved to 20/63. These findings were confirmed for the entire 6-month follow-up duration. No ocular or non-ocular adverse events were recorded. This is the first reported case of complete regression of macular edema in a diabetic patient after subcutaneous injection of exenatide.

Topics: Diabetes Mellitus, Type 2; Diabetic Retinopathy; Exenatide; Female; Humans; Hypoglycemic Agents; Macular Edema; Middle Aged; Peptides; Venoms

Rapid improvement in glycaemic control with GLP-1 receptor agonist (RA) therapy has been reported to be associated with significant progression of diabetic retinopathy. This deterioration is transient, and continuing GLP-1 RA treatment is associated with reversal of this phenomenon. Pre-existent maculopathy, higher grade of retinopathy and longer duration of diabetes may be risk factors for persistent deterioration.

Topics: Blood Glucose; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Disease Progression; Exenatide; Follow-Up Studies; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Glycated Hemoglobin; Humans; Hypoglycemic Agents; Middle Aged; Peptides; Receptors, Glucagon; Risk Factors; Venoms

The breakdown of the inner endothelial blood-retinal barrier (BRB) and subsequent retinal vascular leakage are the main causes of vision loss due to diabetic retinopathy (DR). Exendin-4 (E4) is a long-acting agonist of the glucagon-like peptide 1 hormone receptor (GLP-1R) that is widely used in clinics and has shown a neuroprotective effect. Our previous studies demonstrated the protective effect of E4 in early experimental DR; however, the molecular and cellular mechanisms that mediate this protective effect are not fully known. The BRB plays a key role in DR. We speculated that E4 may exert its protective effects on the BRB. To test this hypothesis, E4 (0.1 μg/2 μL/eye) or vehicle were intravitreally injected into diabetic Goto-Kakizaki(GK) rats and control animals. The results revealed that E4 significantly inhibited the reductions in electroretinogram (ERG) amplitudes in the GK rats, particularly in the b-wave and oscillatory potentials (OPs). E4 upregulated retinal GLP-1R expression and downregulated the expressions of placental growth factor (PLGF) and vascular endothelial growth factor (VEGF) via the ERK and AKT/PKB pathways. Decreases in tight junction protein (i.e., claudin-5 and occludin) expression and increases in Evans blue permeation (EBP) were inhibited by E4. Similar results were also found in primary rat Müller cells in high glucose concentration cultures in vitro. We conclude that E4 may protect the BRB from diabetic insults by decreasing PLGF and ICAM-1 expression and maintaining the integrity of the BRB. Thus, E4 treatment may be an effective therapeutic approach for DR.

Topics: Animals; Blood-Retinal Barrier; Capillary Permeability; Claudin-5; Diabetic Retinopathy; Disease Models, Animal; Electroretinography; Exenatide; Glucagon-Like Peptide-1 Receptor; Hypoglycemic Agents; Intercellular Adhesion Molecule-1; Intravitreal Injections; Male; MAP Kinase Signaling System; Occludin; Peptides; Placenta Growth Factor; Pregnancy Proteins; Rats; Rats, Wistar; Receptors, Glucagon; Retinal Vessels; Vascular Endothelial Growth Factor A; Venoms

Topics: Cardiovascular Diseases; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Drug Therapy, Combination; Evidence-Based Medicine; Exenatide; Female; Humans; Hypertension; Hypoglycemic Agents; Male; Metformin; Peptides; Venoms

To evaluate the protective effect of intravitreal injection of exendin-4 analogue (E4a) in early diabetic retinopathy (DR) and to explore its possible mechanism.. Forty Sprague-Dawley rats were divided into three groups: normal (N), diabetic (D), and E4a-treated diabetic rats (E4a). Diabetes was induced by streptozotocin. Rats in the E4a group were treated with E4a (0.1 μg/2μL/eye), whereas the N and D groups were treated with the equivalent volume of normal saline. Electroretinography was performed at 1 month and 3 months after diabetes onset. Thicknesses and cell counts in each layer of the retina were evaluated. The concentration of glutamate was measured by high-performance liquid chromatography (HPLC). Expressions of glucagon-like peptide-1 receptor (GLP-1R) and GLAST (excitatory amino acid transporter) were detected at mRNA and protein levels and verified by immunohistochemistry in vitro and in vivo. The rMc-1 cells were cultured under high-glucose medium (25 mM), which mimicked diabetic conditions. Effects of E4a (10 μg/mL) were also tested in the rMc-1 culture system.. E4a prevented the reduction in b-wave amplitude and oscillatory potential amplitude caused by diabetes. It also prevented the cell loss of outer nuclear layer and inner nuclear layer; the thickness and cell count in the outer nuclear layer were decreased in 1-month diabetic rats. The concentration of glutamate in the retina was higher in diabetic rats and was significantly reduced in the E4a-treated group. Consistent with such changes, retinal GLP-1R and GLAST expression were reduced in the diabetic retina but upregulated in E4a-treated rats. No improvement was found in the retina in both functional and morphologic parameters 3 months after treatment.. Intravitreal administration of E4a can prevent the retina, functionally and morphologically, from the insults of diabetes in rats. GLP-1R and GLAST were proved to exist in the rat retina, and their lowered expressions in the diabetic retina might be related to retinal damage by increasing the retinal glutamate. E4a might protect the retina by reducing the glutamate level through upregulating GLP-1R and GLAST, as observed in retinal Müller cells in this study, but this protective effect was transient. Thus, this could be a potential approach for the treatment of DR.

Topics: Animals; Blotting, Western; Cell Count; Cells, Cultured; Chromatography, High Pressure Liquid; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Electroretinography; Excitatory Amino Acid Transporter 1; Exenatide; Fluorescent Antibody Technique, Indirect; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Glutamic Acid; Hypoglycemic Agents; Intravitreal Injections; Male; Microscopy, Fluorescence; Peptides; Rats; Rats, Sprague-Dawley; Receptors, Glucagon; Retina; RNA, Messenger; Venoms

Diabetic retinopathy (DR) is one of the leading causes of blindness, affecting over 90% of diabetics. Exendin-4 (E4) is a potent and long-acting agonist of the glucagon-like peptide-1 (GLP-1) receptor. GLP-1 is an insulinotropic gut peptide, which normalizes blood glucose level and is now being tested in clinical trials as a treatment for diabetes. The purpose of our study was to explore the protective effect of subcutaneous (sc.) exendin-4 analogue (E4a) on early DR.. Expression of GLP-1R was detected at both mRNA and protein levels and verified by immunohistochemistry. Thirty-six Sprague-Dawley (SD) rats were included in the experiment. Diabetes was induced by intraperitoneal injection (ip) of streptozotocin (STZ). The rats were divided into three groups: normal control (N), diabetic control (D) and E4a-treated diabetic (E4a) group. For the E4a group, the rats were treated with E4a (sc.0.05 microg/g BW/day); for the N and D groups, the rats were treated with normal saline (NS, sc). Blood glucose levels and body weight were measured weekly. Electroretinogram (ERG) was performed 1 and 3 months after diabetes onset. The retinal thickness and cell counts in each layer were evaluated under light microscopy after ERG examination.. GLP-1R was expressed at both mRNA and protein levels in the retina of SD rats. Immunostaining of the rat retina revealed that GLP-1R was predominantly expressed in the inner layer of the retina. E4a can reduce the blood glucose level of diabetic rats to the normal control level. B-wave amplitudes and OPs decreased with the progress of diabetes, and E4a prevents the loss of b-wave amplitude and OPs caused by diabetes. The retinal thickness was reduced in a diabetes-duration-dependent fashion. The cell counts of both ONL and INL were reduced accordingly in the diabetic rats. E4a prevented cell loss and maintained a normal thickness.. GLP-1R is expressed in rat retina. Apoptosis is an important constituent of retinal cell death in early DR. E4a administration can reverse the changes of ERG, prevent the retinal cell death and maintain normal retinal thickness in diabetic rats. Therefore, this is a potent approach for treatment of early DR.

Topics: Animals; Blood Glucose; Blotting, Western; Cell Count; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Electroretinography; Exenatide; Glucagon-Like Peptide 1; Glucagon-Like Peptide-1 Receptor; Hypoglycemic Agents; Immunoenzyme Techniques; Injections, Subcutaneous; Male; Peptides; Polymerase Chain Reaction; Rats; Rats, Sprague-Dawley; Receptors, Glucagon; Retina; Retinal Photoreceptor Cell Inner Segment; Retinal Photoreceptor Cell Outer Segment; RNA, Messenger; Venoms

Topics: Adult; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Exenatide; Female; Glycated Hemoglobin; Humans; Hypoglycemic Agents; Peptides; Venoms