4-hydroxy-2-nonenal and Diabetic-Retinopathy

Microvascular changes and retinal degeneration precede diabetic retinopathy. Oxidative stress alters several intracellular signaling pathways, which form the basis of diabetic retinopathy. Many antioxidants have been investigated as possible preventive and therapeutic remedies for diabetic retinopathy. The current study investigated the modulatory effects of trans-resveratrol on streptozotocin-induced type 1 diabetes mediated changes in the transcription and levels of apoptosis-related proteins and mitogen-activated protein kinases (MAPKs) in the retinal pigment epithelium (RPE) of adult male dark Agouti rats. In control rats, 5 mg/kg/d trans-resveratrol administration for 30 days increased gene expressions of tumor suppressor protein 53, Bcl2-associated X protein, B-cell lymphoma-2 (Bcl2), Caspase-3 (CASP3), CASP8 and CASP9, p38αMAPK, c-Jun N-terminal kinase-1 (JNK1), and extracellular signal-regulated kinase-1 (ERK1). On the other hand, diabetes decreased gene expressions of CASP3, CASP8, p38αMAPK, JNK, and ERK1. Trans-resveratrol reversed the inhibited gene expressions of CASP8, p38αMAPK, JNK, and ERK1 to normal control levels in diabetic rats. Trans-resveratrol normalized diabetes-induced upregulation of CASP3 and -9, cytochrome-c, Bcl-2, and ERK1 proteins. In conclusion, Trans-resveratrol-induced alterations in gene expressions do not seem to affect RPE functions as they do not reflect as altered protein functions. Trans-resveratrol imparts its protective effects by normalizing apoptosis-related proteins and ERK1 but does not affect JNK proteins. Trans-resveratrol causes cytostasis in RPE of normal rats by upregulating Bcl2 protein and apoptotic proteins.

Topics: Aldehydes; Animals; Antigens, Bacterial; Apoptosis; Bacterial Toxins; Blood Glucose; Body Weight; Caspase 3; Caspase 8; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetic Retinopathy; Male; MAP Kinase Signaling System; Mitogen-Activated Protein Kinases; Rats; Resveratrol; Retinal Pigment Epithelium; Streptozocin; Up-Regulation

Diabetic retinopathy (DRP) is the formation of edema and small vessels in the retina due to high blood glucose levels. Asprosin is a hormone that stimulates the release of glucose from the liver into the circulation. Considering the relationship between oxidative stress and DRP, our study aimed to determine the levels of the oxidative stress markers 4-hydroxynonenal (4-HNE) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), as well as asprosin, in the blood and aqueous humor (Aq) of patients with and without DRP.. Thirty patients with single-eye DRP and cataract (DRP + C), 30 patients with diabetes mellitus and cataract without DRP (DM + C), and 30 healthy control (CON) participants were enrolled into this retrospective study. Except for healthy controls, Aq and blood samples were taken from these patients during their cataract operation. Asprosin, 4-HNE, and 8-OHdG concentrations were analyzed using enzyme-linked immunosorbent assays.. In patients with DRP, the levels of asprosin, 4-HNE, and 8-OHdG were significantly higher in both Aq and blood samples compared with the group of patients without DRP.. These findings suggest that the measurement of asprosin, 4-HNE, and 8-OHdG levels may support clinicians in determining the risk of DRP development.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Aldehydes; Aqueous Humor; Biomarkers; Cataract; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Enzyme-Linked Immunosorbent Assay; Female; Fibrillin-1; Humans; Male; Middle Aged; Oxidative Stress; Retrospective Studies

4-Hydroxy-2-nonenal (4-HNE) is a major reactive aldehyde formed by lipid peroxidation, and it plays an important role in the pathogenesis of several vascular diseases, including diabetes mellitus. In this study, we examined the effects of 4-HNE on the vasodilatory mechanisms of rat retinal arterioles. The retinal vasodilator responses were assessed by measuring the diameter of retinal arterioles in the fundus images. Intravitreal injection of 4-HNE significantly prevented the vasodilation of retinal arterioles induced by the β2-adrenoceptor agonist salbutamol but not the nitric oxide donor (±)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (NOR3). Iberiotoxin, an inhibitor of large-conductance KCa (BKCa) channels, significantly reduced the salbutamol-induced vasodilation of retinal arterioles. The vasodilator effect of BMS-191011, a BKCa channel opener, on retinal arterioles was significantly attenuated by 4-HNE. These results suggest that 4-HNE attenuates retinal vasodilator responses to β2-adrenoceptor agonists through the impairment of the BKCa pathway. The direct effect of 4-HNE on retinal blood vessels may, therefore, contribute to the retinal vascular dysfunction observed in patients with diabetes mellitus.

Topics: Adrenergic beta-2 Receptor Agonists; Albuterol; Aldehydes; Animals; Arterioles; Blood Pressure; Diabetic Retinopathy; Heart Rate; Intravitreal Injections; Large-Conductance Calcium-Activated Potassium Channels; Male; Oxidative Stress; Rats, Wistar; Receptors, Adrenergic, beta-3; Retinal Artery; Vasodilation

Hyperglycemia-induced retinal oxidative and nitrative stress can accelerate vascular cell aging, which may lead to vascular dysfunction as seen in diabetes. There is no information on whether this may contribute to the progression of diabetic retinopathy (DR). In this study, we have assessed the occurrence of senescence-associated markers in retinas of streptozotocin-induced diabetic rats at 8 and 12 weeks of hyperglycemia as compared to normoglycemic aging (12 and 14 months) and adult (4.5 months) rat retinas. We have found that in the diabetic retinas there was an up-regulation of senescence-associated markers SA-β-Gal, p16INK4a and miR34a, which correlated with decreased expression of SIRT1, a target of miR34a. Expression of senescence-associated factors primarily found in retinal microvasculature of diabetic rats exceeded levels measured in adult and aging rat retinas. In aging rats, retinal expression of senescence associated-factors was mainly localized at the level of the retinal pigmented epithelium and only minimally in the retinal microvasculature. The expression of oxidative/nitrative stress markers such as 4-hydroxynonenal and nitrotyrosine was more pronounced in the retinal vasculature of diabetic rats as compared to normoglycemic aging and adult rat retinas. Treatments of STZ-rats with the anti-nitrating drug FeTPPS (10mg/Kg/day) significantly reduced the appearance of senescence markers in the retinal microvasculature. Our results demonstrate that hyperglycemia accelerates retinal microvascular cell aging whereas physiological aging affects primarily cells of the retinal pigmented epithelium. In conclusion, hyperglycemia-induced retinal vessel dysfunction and DR progression involve vascular cell senescence due to increased oxidative/nitrative stress.

Topics: Aging; Aldehydes; Animals; Cellular Senescence; Cyclin-Dependent Kinase Inhibitor p16; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Immunohistochemistry; Lipids; Male; MicroRNAs; Nitrogen; Oxidative Stress; Rats; Rats, Sprague-Dawley; Retina; Retinal Vessels; RNA, Messenger; Sirtuin 1; Streptozocin

Diabetes is associated with nitrosative stress in multiple tissues. Overactivation of the Wnt pathway has been shown to play a pathogenic role in diabetic retinopathy (DR). The purpose of this study was to investigate whether nitrosative stress contributes to aberrant activation of Wnt signaling in diabetes.. Nitrosative stress induced by peroxynitrite (PN), 4-hydroxynonenal (HNE), or high glucose (HG) in retinal cells was assessed by a dichlorofluorescein fluorescence assay or by Western blot analysis and enzyme-linked immunosorbent assay of 3-nitrotyrosine (3-NT). These nitrosative stress inducers activated the canonical Wnt pathway, as shown by Western blot analysis of phosphorylated low-density lipoprotein receptor-related protein 6 (pLRP6), total and nuclear β-catenin levels, Luciferase reporter assay, and expression of the Wnt target genes intercellular adhesion molecule 1 (ICAM-1) and vascular endothelial growth factor (VEGF). Uric acid (UA), a PN scavenger, and 5,10,15,20-Tetrakis (4-sulfonatophenyl) porphyrinato Iron III Chloride (FeTPPS), a PN decomposition catalyst, suppressed Wnt signaling and ICAM-1 and VEGF overexpression induced by PN, HNE, and HG. Furthermore, UA and FeTPPS also inhibited Wnt signaling induced by the Wnt ligand. In streptozotocin-induced diabetic rats, retinal levels of 3-NT, β-catenin, nuclear β-catenin, pLRP6, VEGF, and ICAM-1 were markedly increased. UA treatment for 6 weeks ameliorated diabetes-induced Wnt signaling in the diabetic rat retina. The UA treatment also decreased inflammatory cell infiltration and extraverted serum albumin in the perfused retina of diabetic rats, suggesting decreased retinal inflammation and vascular leakage.. Nitrosative stress in diabetes contributes to Wnt pathway activation in the retina, and Wnt signaling may mediate the pathogenic effects of nitrosative stress in DR.

Topics: Aldehydes; Animals; Blotting, Western; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Enzyme-Linked Immunosorbent Assay; Glucose; Peroxynitrous Acid; Signal Transduction; Uric Acid; Wnt Signaling Pathway

Diabetic retinopathy (DR) is characterized by increased oxidative and nitrosative stress, both of which lead to neurotoxicity and vascular permeability. Previous studies on a variety of organs indicate that hydrogen-rich saline not only has considerable antioxidant and anti-inflammatory properties, but also suppresses oxidative stress-induced injury. In the present study, we assessed the effects of hydrogen-rich saline on neurovascular dysfunction and oxidative stress in an animal model (rat) of DR.. Male Sprague-Dawley rats with streptozotocin (STZ)-induced diabetes mellitus (DM) were injected intraperitoneally with 5 ml/kg hydrogen-saturated (experimental) or plain (control) saline daily for one month. Visual function and blood-retinal barrier (BRB) integrity were evaluated by electroretinography (ERG) and bovine serum albumin (BSA)-fluorescence, respectively. Histological changes in the inner retina were assessed by light microscopy. Biomarkers of oxidative stress, including 4-hydroxynonenal (4-HNE) and 8-hydroxy-2-deoxyguanosine (8-OH-dG), and antioxidant enzymes, including superoxide dismutase, glutathione peroxidase, glutathione reductase and glutathione transferase, were evaluated by ELISA. Synaptophysin and brain-derived neurotrophic factor (BDNF) levels were measured by immunoblotting.. STZ-diabetic rats were marked by clearly reduced b-wave amplitudes and oscillatory potentials, DM-related BRB breakdown and histological changes in the inner retina, all of which were suppressed following treatment with hydrogen-rich saline. Furthermore, hydrogen-rich saline reduced oxidative stress, increased antioxidant enzyme activities and preserved synaptophysin and BDNF levels in the diabetic rat retina.. Based on its inhibition of oxidative stress and up-regulation of anti-oxidative enzymes, we conclude that hydrogen-rich saline is a potentially valuable therapeutic modality for the treatment of DR.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aldehydes; Animals; Blood Glucose; Blood-Retinal Barrier; Blotting, Western; Body Weight; Brain-Derived Neurotrophic Factor; Deoxyguanosine; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Electroretinography; Enzyme-Linked Immunosorbent Assay; Male; Oxidative Stress; Oxidoreductases; Rats; Rats, Sprague-Dawley; Retinal Neovascularization; Sodium Chloride; Synaptophysin

Our recent studies suggest that activation of the wingless-type MMTV integration site (WNT) pathway plays pathogenic roles in diabetic retinopathy and age-related macular degeneration. Here we investigated the causative role of oxidative stress in retinal WNT pathway activation in an experimental model of diabetes.. Cultured retinal pigment epithelial cells and retinal capillary endothelial cells were treated with a lipid peroxidation product, 4-hydroxynonenal (HNE), and an antioxidant, N-acetyl-cysteine (NAC). In vivo, rats with streptozotocin-induced diabetes were treated by NAC for 8 weeks. Activation of the canonical WNT pathway was measured by TOPFLASH assay and by western blot analysis of WNT pathway components and a WNT target gene, Ctgf. Oxidative stress in the retina was evaluated by immunostaining of HNE and 3-nitrotyrosine.. Levels of phosphorylated and total LDL receptor-related protein (LRP)6, and cytosolic β-catenin, as well as transcriptional activity of T cell factor (TCF)/β-catenin were significantly increased by HNE. The production of connective tissue growth factor (CTGF) was also upregulated by HNE. NAC blocked the WNT pathway activation induced by HNE. Furthermore, LRP6 stability was increased by HNE and decreased by NAC. Retinal levels of HNE and 3-nitrotyrosine were significantly increased in diabetic rats, compared with those in non-diabetic rats. In the same diabetic rat retinas, levels of LRP6, cytosolic β-catenin and CTGF were significantly increased. NAC treatment reduced HNE and 3-nitrotyrosine levels and attenuated the upregulation of LRP6, β-catenin and CTGF in diabetic rat retina.. Lipid peroxidation products activate the canonical WNT pathway through oxidative stress, which plays an important role in the development of retinal diseases.

Topics: Acetylcysteine; Aldehydes; Animals; beta Catenin; Blotting, Western; Cell Line; Connective Tissue Growth Factor; Diabetic Retinopathy; Female; Humans; Hydrogen Peroxide; Immunohistochemistry; Ketocholesterols; LDL-Receptor Related Proteins; Lipid Peroxidation; Low Density Lipoprotein Receptor-Related Protein-6; Oxidative Stress; Rats; TCF Transcription Factors

Renal protection against diabetes-induced pathogenic injuries by multiple exposures to low-dose radiation (LDR) was investigated to develop a novel approach to the prevention of renal disease for diabetic subjects. C57BL/6J mice were given multiple low-dose streptozotocin (STZ; 6 x 60 [corrected] mg/kg) to produce a type 1 diabetes. Two weeks after diabetes onset, some of diabetic mice and age-matched nondiabetic mice were exposed whole body to 25 mGy X-rays every other day for 2, 4, 8, 12, and 16 wk. Diabetes caused a significant renal dysfunction, shown by time-dependent increase in urinary microalbumin (Malb) and decrease in urinary creatinine (Cre), and pathological changes, shown by significant increases in renal structural changes and PAS-positive staining. However, diabetes-induced renal dysfunction and pathological changes were significantly, albeit partially, attenuated by multiple exposures to LDR. Furthermore, LDR protection against diabetes-induced renal dysfunction and pathological changes was associated with a significant suppression of diabetes-increased systemic and renal inflammation, shown by significant increases in serum and renal TNFalpha, ICAM-1, IL-18, MCP-1, and PAI-1 contents. To further explore the mechanism by which LDR prevents diabetes-induced renal pathological changes, renal oxidative damage was examined by Western blotting and immunohistochemical staining for 3-nitrotyrosine and 4-hydroxynonenal. Significant increase in oxidative damage was observed in diabetic mice, but not diabetic mice, with LDR. Renal fibrosis, examined by Western blotting of connective tissue growth factor and Masson's trichrome staining, was also evident in the kidneys of diabetic mice but not diabetic mice with LDR. These results suggest that multiple exposures to LDR significantly suppress diabetes-induced systemic and renal inflammatory response and renal oxidative damage, resulting in a prevention of the renal dysfunction and fibrosis.

Topics: Albuminuria; Aldehydes; Animals; Blotting, Western; Chemokine CCL2; Creatinine; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetic Retinopathy; Intercellular Adhesion Molecule-1; Interleukin-18; Male; Mice; Mice, Inbred C57BL; Nephritis; Random Allocation; Reverse Transcriptase Polymerase Chain Reaction; RNA; Serpin E2; Serpins; Tumor Necrosis Factor-alpha; Tyrosine

Oxidative stress has been implicated in pathogenesis of diabetic retinopathy. It has been hypothesized that hyperglycaemia may damage vascular endothelium and retina by inducing the synthesis of oxidant reactive species. The aim of the present study was to estimate lipid peroxidation by detecting the concentration of malondialdehyde and 4-hydroxynonenal in diabetic patients with retinopathy, subjects without retinopathy and the reference group. Sixty-one patients were studied, including 30 patients with severe non-proliferative retinopathy in NIDDM and 31 diabetic patients without retinopathy. The reference group were 11 systemic healthy patients. Concentration of malondialdehyde and 4-hydroxynonenal was measured in plasma sample using a Lipid peroxidation Assay Kit (Calbiochem-Novabiochem Corp.). The concentration of lipid peroxidation products in patients with retinopathy was statistically significantly elevated in comparison to diabetic patients without retinopathy (p < 0.001) and the reference group (p < 0.001). We do not notice any significant differences in levels of MDA and 4-HNE between patients without diabetic retinopathy and the reference group. In view of our results we can conclude that oxidative stress is an important risk factor in the development of diabetic retinopathy.

Topics: Aldehydes; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Humans; Lipid Peroxidation; Malondialdehyde; Oxidative Stress; Reference Values; Retina