losartan-potassium and Hyperglycemia

Proliferative diabetic retinopathy (PDR), characterized by pathologic retinal angiogenesis, is a major cause of blindness in the USA and globally. Treatments targeting vascular endothelial growth factor (VEGF) have emerged as a beneficial part of the therapeutic armamentarium for this condition, highlighting the utility of identifying and targeting specific pathogenic molecules. There continues to be active research into the molecular players regulating retinal angiogenesis, including pro-angiogenic factors, anti-angiogenic factors, and integrins and matrix proteinases. New insights have been especially prominent regarding molecules which regulate specialized endothelial cells called tip cells, which play a lead role in endothelial sprouting. Together, these research efforts are uncovering new, important molecular regulators of retinal angiogenesis, which provide fertile areas for therapeutic exploration. This review discusses potential molecular targets, with an emphasis towards newer targets.

Topics: Angiogenesis Inhibitors; Blindness; Diabetic Retinopathy; Disease Progression; Erythropoietin; Female; Humans; Hyperglycemia; Macular Edema; Male; Retinal Neovascularization; Vascular Endothelial Growth Factor A

Topics: Angiopoietin-1; Animals; Cell Movement; Diabetic Retinopathy; Erythropoietin; Humans; Hyperglycemia; Inflammation; Mice; Mice, Transgenic; Neovascularization, Pathologic; Neovascularization, Physiologic; Receptor, TIE-2; Retina; Vascular Endothelial Growth Factor A

Topics: Acidosis; Apoptosis; Brain Ischemia; Erythropoietin; Fever; Fibrinolytic Agents; Forecasting; Humans; Hyperglycemia; Myocardial Ischemia; Tissue Plasminogen Activator

Diabetic nephropathy is traditionally considered to be a primarily glomerular disease, although this contention has recently been challenged. Early tubular injury has been reported in patients with diabetes mellitus whose glomerular function is intact. Chronic hypoxia of the tubulointerstitium has been recognized as a mechanism of progression that is common to many renal diseases. The hypoxic milieu in early-stage diabetic nephropathy is aggravated by manifestations of chronic hyperglycemia-abnormalities of red blood cells, oxidative stress, sympathetic denervation of the kidney due to autonomic neuropathy, and diabetes-mellitus-induced tubular apoptosis; as such, tubulointerstitial hypoxia in diabetes mellitus might be an important early event. Chronic hypoxia could have a dominant pathogenic role in diabetic nephropathy, not only in promoting progression but also during initiation of the condition. Early loss of tubular and peritubular cells reduces production of 1,25-dihydroxyvitamin D3 and erythropoietin, which, together with dysfunction of their receptors caused by the diabetic state, diminishes the local trophic effects of the hormones. This diminution could further compromise the functional and structural integrity of the parenchyma and contribute to the gradual decline of renal function.

Topics: Animals; Calcitriol; Capillaries; Chronic Disease; Diabetic Nephropathies; Disease Progression; Erythropoietin; Filtration; Humans; Hyperglycemia; Hypoxia; Kidney; Kidney Glomerulus; Kidney Tubules; Oxidative Stress; Proteinuria; Receptors, Calcitriol

Mesenchymal stem cell (MSC)-based therapies have demonstrated positive outcomes for treating cardiovascular disease. However, the proliferative ability of MSCs decreases during chronic exposure to hyperglycaemia; their ability to contribute to endogenous injury repair is thus reduced. Erythropoietin (EPO) was recently reported to protect against hyperglycaemia-related injury in various cells and may be a good candidate for enhancing MSC functions under hyperglycaemic conditions.. Bone marrow-derived MSCs were isolated from male donor rats weighing 60-80 g. The roles of EPO in regulating cell viability, senescence, angiogenesis and inflammation were investigated using the Cell Counting Kit-8 (CCK-8) assay and 5-ethynyl-2'-deoxyuridine (EdU) assays; senescence-associated β-galactosidase (SA-β-gal) staining; VEGF, HGF, IGF, bFGF ELISAs and TNF-α ELISA, respectively. ROS production was measured by flow cytometry. The expression levels of Akt, forkhead box class O3a (FoxO3a) and VEGF proteins in MSCs were analysed by western blotting. Matrigel was used for tube formation assays.. The results of the current study showed that EPO has beneficial effects on MSCs exposed to hyperglycaemia by promoting proliferation, inhibiting senescence and the release of pro-inflammatory factors, increasing the secretion of proangiogenic cytokines, and enhancing the ability of MSCs to stimulate tube formation among human umbilical vein endothelial cells (HUVECs). In addition, the beneficial effects of EPO may result from the activation of the Akt/FoxO3a signalling pathway.. Our study demonstrates for the first time that EPO protects MSCs from hyperglycaemia-induced damage by targeting the Akt/FoxO3a signalling pathway.

Topics: Animals; Cell Proliferation; Cytoprotection; Erythropoietin; Forkhead Box Protein O3; Human Umbilical Vein Endothelial Cells; Humans; Hyperglycemia; Mesenchymal Stem Cells; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; Signal Transduction

Erythropoietin (EPO) is known to stimulate erythropoiesis after binding with its specific receptor. In clinics, EPO is widely used in hemodialyzed patients with diabetes. However, changes in the expression of the erythropoietin receptor (EPOR) under diabetic conditions are still unclear. Therefore, we investigated EPOR expression both in vivo and in vitro. Streptozotocin-induced type 1-like diabetic rats (STZ rats) were used to evaluate the blood glucose-lowering effects of EPO. The expression and activity of the transducer and activator of transcription 3 (STAT3), the potential signaling molecule, was investigated in cultured rat skeletal myoblast (L6) cells incubated in high-glucose (HG) medium to mimic the in vivo changes. The EPO-induced reduction in hyperglycemia was more pronounced in diabetic rats. The increased EPOR expression in the soleus muscle of diabetic rats was reversed by the reduction in hyperglycemia. Glucose uptake was also increased in high-glucose (HG)-treated L6 cells. Western blotting results indicated that the EPO-induced hyperglycemic activity was enhanced mainly through an increase in EPOR expression. Increased EPOR expression was associated with the enhanced nuclear expression of STAT3 in HG-exposed L6 cells. In addition, treatment with siRNA specific to STAT3 reversed the increased expression of EPOR observed in these cells. Treatment with Stattic at a dose sufficient to inhibit STAT3 reduced the expression level of EPOR in STZ rats. In conclusion, the increased expression of EPOR by hyperglycemia is mainly associated with an augmented expression of nuclear STAT3, which was identified both in vivo and in vitro in the present study.

Topics: Animals; Blood Glucose; Cells, Cultured; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Erythropoiesis; Erythropoietin; Hyperglycemia; Male; Rats; Rats, Wistar; Receptors, Erythropoietin; Streptozocin

The signal transducer and activator of transcription 3 (STAT3) is known to be involved in hypertrophy and fibrosis in cardiac dysfunction. The activation of STAT3 via the phosphorylation of STAT3 is required for the production of functional activity. It has been established that lipopolysaccharide (LPS)‑induced phosphorylation of STAT3 in cardiomyocytes primarily occurs through a direct receptor‑mediated action. This effect is demonstrated to be produced rapidly. STAT3 in cardiac fibrosis of diabetes is induced by high glucose through promotion of the STAT3‑associated signaling pathway. However, the time schedule for STAT3 activation between LPS and high glucose appears to be different. Therefore, the difference in STAT3 activation between LPS and hyperglycemia in cardiomyocytes requires elucidation. The present study investigated the phosphorylation of STAT3 induced by LPS and hyperglycemia in the rat cardiac cell line H9c2. Additionally, phosphorylation of STAT3 induced by erythropoietin (EPO) via receptor activation was compared. Then, the downstream signals for fibrosis, including the connective tissue growth factor (CTGF) and matrix metalloproteinase (MMP)‑9, were determined using western blotting, while the mRNA levels were quantified. LPS induced a rapid elevation of STAT3 phosphorylation in H9c2 cells within 30 min, similar to that produced by EPO. However, LPS or EPO failed to modify the mRNA level of STAT3, and/or the downstream signals for fibrosis. High glucose increased STAT3 phosphorylation to be stable after a long period of incubation. Glucose incubation for 24 h may augment the STAT3 expression in a dose‑dependent manner. Consequently, fibrosis‑associated signals, including CTGF and MMP‑9 protein, were raised in parallel. In the presence of tiron, an antioxidant, these changes by hyperglycemia were markedly reduced, demonstrating the mediation of oxidative stress. Therefore, LPS‑ or EPO‑induced STAT3 phosphorylation is different compared with that caused by high glucose in H9c2 cells. Sustained activation of STAT3 by hyperglycemia may promote the expression of fibrosis‑associated signals, including CTGF and MMP‑9, in H9c2 cells. Therefore, regarding the cardiac dysfunctions associated with diabetes and/or hyperglycemia, the identification of nuclear STAT3 may be more reliable compared with the assay of phosphorylated STAT3 in cardiac cells.

Topics: Animals; Cell Line; Connective Tissue Growth Factor; Erythropoietin; Hyperglycemia; Lipopolysaccharides; Matrix Metalloproteinase 9; Myocytes, Cardiac; Oxidative Stress; Phosphorylation; Protein Processing, Post-Translational; Rats; Signal Transduction; STAT3 Transcription Factor

Erythropoietin (EPO), which is clinically used for renal anaemia, reportedly exerts beneficial pleiotropic effects in atherosclerosis. This aim of this study was to investigate the effects of EPO on macrophage inflammation and polarization under hyperglycaemic conditions and to identify the effects of EPO-treated macrophage supernatants (SNs) on endothelial cell (EC) function.. Peritoneal macrophages (pMΦs) were isolated from normal, diabetic or EPO-injected mice. Pro-inflammatory factors were detected by qRT-PCR and ELISA, and macrophage phenotype markers were evaluated by flow cytometry. High glucose culture was used to mimic the hyperglycaemic microenvironment of diabetes mellitus (DM) in vitro. After exposure to various doses of stimuli, macrophage inflammation and phenotype were detected via ELISA, qRT-PCR and flow cytometry. The underlying mechanism was investigated through western blotting. To examine the communication between macrophages and ECs, ECs were cultured with the SN of macrophages treated with different stimuli, and the tube formation ability of ECs was detected using Matrigel. The VEGF, ICAM-1 and VCAM-1 protein expression levels were determined by western blotting, and the nitric oxide (NO) and endothelin-1 (ET-1) expression levels were measured with a nitric oxide indicator and by ELISA, respectively.. EPO treatment increased the M2 macrophage population and decreased the number of M1 macrophages. EPO decreased the secretion of pro-inflammatory factors, including TNF-α, iNOS and IL-6. The JAK2/STAT3 signalling pathway was also identified as being involved in the M1 macrophage transition. The SN of macrophages treated with EPO (SN-EPO) presented increased NO and ET-1 levels and decreased ICAM-1 and VCAM-1 levels. Tube formation assays revealed that the SN-EPO promoted the ability of ECs to form capillary-like structures in vitro. In contrast, AZD1480, a JAK2 inhibitor, abolished this SN-EPO effect.. EPO treatment alleviated the inflammatory reaction in DM mice and inhibited M1 polarization through the JAK2/STAT3 pathway. Moreover, EPO treatment promoted the tube formation ability of ECs in a VEGF-dependent manner and decreased the production of adhesion molecules, a vasodilator and a vasoconstrictor.

Topics: Animals; Cell Polarity; Diabetes Mellitus; Erythropoietin; Humans; Hyperglycemia; Inflammation; Intercellular Adhesion Molecule-1; Janus Kinase 2; Macrophages; Macrophages, Peritoneal; Male; Mice, Inbred C57BL; Neovascularization, Physiologic; Phenotype; Signal Transduction; STAT3 Transcription Factor; Vascular Cell Adhesion Molecule-1

Erythropoietin (EPO) is widely used in diabetic patients receiving hemodialysis. The role of EPO in glucose homeostasis remains unclear. Therefore, we investigated the effect of EPO on hyperglycemia in rats with type 1-like diabetes.. Rats with streptozotocin-induced type 1-like diabetes (STZ rats) were used to estimate the blood glucose-lowering effects of EPO, and changes in the expression levels of glucose transporter 4 (GLUT4) and the hepatic enzyme phosphoenolpyruvate carboxykinase (PEPCK) were identified by Western blot analysis.. EPO attenuated the hyperglycemia in the STZ rats in a dose-dependent manner without altering the hematopoietic parameters, including the hematocrit and number of red blood cells. The involvement of the EPO receptor (EPOR) was identified using EPOR-specific antibodies. In addition, injection of EPO enhanced the glucose utilization, which was assessed using an intravenous glucose tolerance test in rats. However, blood insulin was not changed by EPO in this assay, showing the insulinotropic action of EPO. Moreover, EPO treatment increased the insulin sensitivity. Western blots indicated that the phosphorylation of AMP-activated protein kinase was enhanced by EPO to support the signaling caused by EPOR activation. Furthermore, the decrease in the GLUT4 level in skeletal muscle was reversed by EPO, and the increase in the PEPCK expression in liver was reduced by EPO, as shown in STZ rats.. Taken together, the results show that EPO injection may reduce hyperglycemia in diabetic rats through activation of EPO receptors. Therefore, EPO is useful for managing diabetic disorders, particularly hyperglycemia-associated changes. In addition, EPO receptor will be a good target for the development of antihyperglycemic agent(s) in the future.

Topics: Animals; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Disease Models, Animal; Erythropoietin; Hyperglycemia; Hypoglycemic Agents; Insulin; Male; Rats; Rats, Wistar; Streptozocin

We studied proliferation, migration, and secretion of NO by bone marrow multipotent mesenchymal stromal cells from Wistar rats during conditioning under hypoxic and hyperglycemic conditions and the effect of erythropoietin on these parameters. A stimulating effect of erythropoietin on cell proliferation under normal conditions and activation of cell proliferation under conditions of hypoxia and hyperglycemia were demonstrated. Erythropoietin abolishes suppression of cell proliferation in culture with normal glucose level under conditions of H2O2-induced hypoxia, while under conditions of hyperglycemia, inhibition of cell proliferation becomes more pronounced. Hypoxia promotes activation of cell migration along the growth factor concentration gradient and addition of erythropoietin to the nutrient medium leads to a decrease in cell migration activity. Erythropoietin stimulates NO production by cells cultured under the conditions of hypoxia and hyperglycemia.

Topics: Animals; Cell Hypoxia; Cell Movement; Cell Proliferation; Cells, Cultured; Erythropoietin; Glucose; Hyperglycemia; Mesenchymal Stem Cells; Nitric Oxide; Rats, Wistar

Erythropoietin (EPO), an essential hormone for erythropoiesis, provides protection against myocardial ischemia/reperfusion (I/R) injury. Hyperglycemia during acute myocardial infarction aggravates organ damage and attenuates the efficacies of various protective measures. This study aimed to investigate the protective role of EPO against myocardial I/R injury under a clinically relevant moderate hyperglycemic condition and its associated mechanisms. Eighty-two Sprague-Dawley rats were randomly assigned to six groups: normoglycemia-Sham, normoglycemia-I/R-control-saline (IRC), normoglycemia-I/R-EPO (IRE), hyperglycemia-Sham, hyperglycemia-IRC, and hyperglycemia-IRE. The rats received 1.2 g/kg dextrose or same volume of normal saline depending on the group. I/R was induced by a 30 min period of ischemia followed by reperfusion for 4 h. For 1 h before I/R injury, intravenous 4000 IU/kg of EPO was administered. EPO pretreatment significantly reduced the number of apoptotic cells and the infarct size compared with those of the control groups. EPO increased GATA-4 phosphorylation and acetylation against I/R in hyperglycemic myocardium. It also enhanced ERK induced GATA-4 post-translational modifications such as increased GATA-4 phosphorylation and acetylation, and decreased GATA-4 ubiquitination following hypoxia-reoxygenation in H9c2 cells in hyperglycemic medium. Increased GATA-4 stability by EPO diminished I/R-related down-regulation of Bcl-2 and reduction of caspase-3 activities in hyperglycemic myocardium. In conclusion, EPO pretreatment before I/R injury conveyed significant myocardial protection under moderate hyperglycemic condition through mechanisms involved in reduction of caspase-3 activity and up-regulation of Bcl-2 in association with enhanced ERK-induced GATA-4 stability.

Topics: Acetylation; Animals; Apoptosis; Cardiotonic Agents; Caspase 3; Cell Line; Erythropoietin; GATA4 Transcription Factor; Hyperglycemia; Male; MAP Kinase Signaling System; Myocardial Reperfusion Injury; Myocytes, Cardiac; Phosphorylation; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Sprague-Dawley; Ubiquitination

Topics: Anemia; Cardiovascular Diseases; Darbepoetin alfa; Diabetes Mellitus, Type 2; Erythropoietin; Glycated Hemoglobin; Hematinics; Humans; Hyperglycemia; Kidney Failure, Chronic

Hyperglycemia is associated with a decreased tolerance to ischemia and an increased severity of renal ischemia reperfusion (I/R) injury. It has been suggested that erythropoietin (EPO) attenuates this effect in normoglycemic animals. This study sought to examine the effects of EPO on treatment renal I/R injury (IRI) in transiently hyperglycemic rats.. Twenty-eight male Wister rats anesthetized with isoflurane received glucose (2.5 g.kg(-1) intraperitoneally) before right nephrectomy. They were randomly assigned to four groups: sham operation (S); IRI (ISO); IRI+EPO, (600 UI kg(-1) low-dose EPO [EL]); and IRI+EPO 5000 UI kg(-1) (high-dose EPO [EH]). IRI was induced by a 25-minute period of left renal ischemia followed by reperfusion for 24 hours. Serum creatinine and glucose levels were measure at baseline (M1), immediately after the ischemic period (M2), and at 24 hours after reperfusion (M3). After sacrificing the animals, left kidney specimens were submitted for histological analysis including flow cytometry to estimate tubular necrosis and the percentages of apoptotic, dead or intact cells.. Scr in the ISO group was significantly higher at M3 than among the other groups. Percentages of early apoptotic cells in ISO group were significantly higher than the other groups. Percentages of late apoptotic cells in S and ISO groups were significantly greater than EL and EH groups. However, no significant intergroup differences were observed regarding the incidence of tubular necrosis.. Our results suggested that, although not preventing the occurrence of tubular necrosis, EPO attenuated apoptosis and glomerular functional impairment among transiently hyperglycemic rats undergoing an ischemia/reperfusion insult.

Topics: Animals; Apoptosis; Blood Glucose; Creatinine; Cytoprotection; Disease Models, Animal; Epoetin Alfa; Erythropoietin; Flow Cytometry; Hyperglycemia; Kidney; Kidney Glomerulus; Kidney Tubules; Male; Necrosis; Nephrectomy; Rats; Rats, Wistar; Recombinant Proteins; Reperfusion Injury; Time Factors

We examined the efficacy of herpes simplex virus vector-mediated gene transfer of erythropoietin in preventing neuropathy in mouse model of streptozotocin-diabetes. A replication-incompetent herpes simplex virus vector with erythropoietin under the control of the human cytomegalovirus promoter (vector DHEPO) was constructed. DHEPO expressed and released erythropoietin from primary dorsal root ganglion neurons in vitro, and following subcutaneous inoculation in the foot, expressed erythropoietin in dorsal root ganglion neurons in vivo. At 2 weeks after induction of diabetes, subcutaneous inoculation of erythropoietin prevented the reduction in sensory nerve amplitude characteristic of diabetic neuropathy measured 4 weeks later, preserved autonomic function measured by pilocarpine-induced sweating, and prevented the loss of nerve fibres in the skin and reduction of neuropeptide calcitonin gene-related peptide in the dorsal horn of spinal cord of the diabetic mice. We further investigated whether vector-mediated local expression of erythropoietin in dorsal root ganglion neurons can protect in vivo as well as in vitro hyperglycemia-induced axonal degeneration. Our findings show that the AKT/GSK-3beta dependent pathway plays an important role in mediating the protection of erythropoietin against diabetic neuropathy. Herpes simplex virus-mediated transfer of erythropoietin to dorsal root ganglia may prove useful in treatment of diabetic neuropathy.

Topics: Animals; Autonomic Nervous System Diseases; Calcitonin Gene-Related Peptide; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Erythropoietin; Ganglia, Spinal; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Hematocrit; Hot Temperature; Hyperglycemia; Mice; Pain Threshold; Peripheral Nervous System Diseases; Sensory Receptor Cells; Simplexvirus; Skin

Short-lasting hypobaric hypoxia was used in male white rats as a stimulus of erythropoietin synthesis (0.42 atm.). Plasma erythropoietin activity was determined by a biologic method on highly sensitive to exogenous erythropoietin recipients-posthypoxic polycytemic mice. Erythropoietin activity was estimated by measuring the percentage of incorporated 59Fe in newly formed erythrocytes of mice under the influence of the examined plasma, using automatic scintillation gamma-counter. Hypoxia induced an increase of plasma erythropoietin activity with 54% in comparison with control animals. Administration of actinomycin D in a dose of 0.4 microgram/g of body mass before exposure of the animals to hypoxia diminished production of erythropoietin with 58% in comparison with that of rats, exposed to pure hypoxia. A suggestion could be made that the formation of erythropoietin requires DNA dependent RNA-synthesis.

Topics: Animals; Dactinomycin; Erythropoietin; Hyperglycemia; Hypoxia; Male; Rats; Rats, Inbred Strains; RNA

Topics: Animals; Blood Glucose; Erythropoietin; Female; Fetal Diseases; Glucose; Hyperglycemia; Hypoxia; Infusions, Intra-Arterial; Insulin; Oxygen; Pregnancy; Sheep