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Devy Deliyanti, Saeed Alrashdi, David R Berka, Karin A Jandeleit-Dahm, Mark E Cooper, Jennifer L Wilkinson-Berka; Inhibition of Nox1, 4 and 5 attenuates vasculopathy and inflammation in rats with hypertensive diabetic retinopathy. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4251.
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© ARVO (1962-2015); The Authors (2016-present)
Hypertension is a causal factor in the vasculopathy and inflammation that occurs in diabetic retinopathy, and there is evidence that reactive oxygen species (ROS) has an important role. We hypothesized that inhibition of ROS derived from NADPH oxidase (Nox) isoforms 1, 4 and 5 would attenuate vasculopathy and related macroglial Muller cell dysfunction as well as inflammation in the retina of hypertensive rats with type-1 diabetes.
Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were made diabetic with streptozotocin and studied for 8 weeks. GKT139601 (GKT) inhibits Nox1 and 4 and also the human/bovine Nox5 isoform and was administered from the onset of diabetes (60mg/kg/day, gavage) (N=21-26/group). Because Nox5 is absent in rodents, transgenic mice expressing human Nox5 in endothelial cells (Nox5VE-Cad+) were generated and studied for 10 weeks. In retina, immunohistochemistry, qPCR or ELISA were used to measure oxidative stress, vasculopathy, Muller cell injury and inflammation. Studies were performed in primary cultures of rat Muller cells and bovine retinal endothelial cells (BREC) exposed to hyperglycaemia (HG, 25mM D-glucose) or HG+GKT (5μM) for 72 hours. Data were analysed by a one-way ANOVA and Mann Whitney U test or a Student’s t-test.
SBP was increased in diabetic SHR compared to diabetic WKY (143.7±2.6 vs 103.2±2.8) and GKT had no effect. All parameters were elevated in diabetic WKY compared to non-diabetic controls. Further increases occurred in diabetic SHR with respect to oxidative stress (8OHdG, p<0.01), vasculopathy (leakage, tight junction proteins, p<0.05; VEGF, angiopoietin2, p<0.01), Muller cell gliosis (p<0.01) and inflammation (microglial density, TNFα, ICAM-1, p<0.05). Treatment with GKT improved all parameters (p<0.01). Nox5VE-Cad+ mice exhibited increased retinal gliosis and vascular leakage (p<0.001). In cultured Muller cells, HG increased Nox1 and 4, VEGF and MCP-1 (p<0.001), which were reduced with GKT (p<0.01). In BREC, HG increased Nox1, 4 and 5, VEGF and ICAM-1, which were reduced with GKT (p<0.01). Differential expression of tight junction proteins occurred. HG reduced occludin and ZO-1 levels in BREC and ZO-3 levels in Muller cells, which were restored by GKT (p<0.05).
These data indicate the potential of Nox1, 4 and 5 inhibition to reduce vision-threatening hypertensive diabetic retinopathy.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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