Topically Administered NOX4 Inhibitor, GLX7013114, Is Efficacious in Treating the Early Pathological Events of Diabetic Retinopathy

Abstract

NADPH oxidases (NOX) are major players in generating reactive oxygen species (ROS), implicated in various neurodegenerative ocular pathologies. The aim of this study was to investigate the role of NOX4 inhibitor (GLX7013114), in two in vivo experimental streptozotocin (STZ) paradigms depicting the early events of diabetic retinopathy (DR). Diabetic-treated animals received GLX7013114 topically (20μl/eye, 10mg/ml, once daily), for 14d (Paradigm A/preventive) and 7d (Paradigm B/treated), 48hr and four wks post STZinjection, respectively. A number of methodologies were employed (immunohistochemistry, western blot, real time PCR, ELISA, PERG) to assess the diabetes induced early events of DR, namely oxidative stress, neurodegeneration and neuroinflammation, and the effect of GLX7013114 on the diabetic insults. GLX7013114, administered as eye-drops (paradigms A,B) was beneficial in treating the oxidative nitrative stress, activation of caspase-3 and micro/macroglia and attenuation of neuronal markers. It also attenuated the diabetes induced increase in VEGF, Evans-Blue leakage and proinflammatory cytokine levels (TNF-α protein, IL-1β/IL-6 mRNA). PERG amplitude values suggested that GLX7013114 protected retinal ganglion cell (RGC) function (Paradigm B). In conclusion, this study provides new findings regarding the pharmacological profile of the novel NOX4 inhibitor GLX7013114, as a promising therapeutic candidate, for the treatment of the early stage of DR.

Investigation of the Effects of a Novel NOX2 Inhibitor, GLX7013170, against Glutamate Excitotoxicity and Diabetes Insults in the Retina

“…The expression of NOX1, NOX2, and NOX4 isoforms of NADPH oxidases has been identified in different types of retinal cells, including macro- and microglia, pericytes, and endothelial cells [ 6 , 7 ], as well as retinal neurons [ 59 ]. Our studies are in agreement with other investigations reporting an increased expression of NOX2 in animal models of DR [ 60 , 61 ], as well as an increased expression of other NOX isoforms [ 9 , 11 , 62 ]. ROS derived from the NOX2 isoform are significantly increased in ESDR, causing mitochondrial damage and further induction of oxidative stress [ 61 ].…”

“…We have previously shown that inhibition of all NOX isoforms (pan-NOX inhibitor, VAS2870) or specific NOX1 inhibition (ML171) reduced the AMPA-induced loss of NOS-expressing amacrine cells when co-administered with AMPA. In contrast, the NOX4-specific inhibitor (GLX7013114), had no effect [ 11 ]. These results suggest that NADPH oxidases are implicated in the AMPA-induced neurodegenerative changes in the retina with NOX isoforms displaying differential roles.…”

“…Moreover, in humans, all known NOX isoforms, including NOX5 and DUOX1/2, are expressed in retinal endothelial cells, where NOX-derived ROS participate in the functional regulation of retinal vasculature [ 6 , 7 ]. Under various retinal pathological conditions, like oxygen-induced retinopathy [ 8 ] and diabetic retinopathy [ 9 , 10 , 11 ], the expression profile of NOX exhibits significant changes, leading to increased production of ROS and the subsequent development of neurotoxic phenomena in the retina. Thus, molecules and strategies aimed to inhibit the activity of NOX isoforms are of particular scientific interest, since there is an essential need for new potential therapeutics for retinal pathologies.…”

Effects of Nox4 upregulation on PECAM-1 expression in a mouse model of diabetic retinopathy

“…Given the pivotal role of NADPH oxidases [ 9 , 36 ], in particular Nox4 [ 3 , 18 ], in ROS generation in retinal ECs, understanding how Nox4 upregulation and increased ROS mediate diabetes-induced vascular damage [ 37 , 38 ] would have high translational significance. Indeed, a recent study demonstrates that topical administration of a Nox4 inhibitor successfully reduced retinal inflammation, neurodegeneration, and vascular leakage [ 39 ]. Future investigation to elucidate the role of Nox4 in the regulation of endothelial tight junction proteins, such as claudin-5, could provide important insight into the mechanisms of Nox4 inhibition on protecting retinal vessels in DR.…”

Diabetic Neuropathy of the Retina and Inflammation: Perspectives

“…Recent studies indicate that several anti-inflammatory therapies ameliorate the pathogenesis of diabetic retinopathy in diabetic models in vivo and in vitro, including IMD-0354, a specific NF-κB blocker [95], GSK-872, specific necroptosis inhibitor [96], hsa_circ_0000047 which targets miR-6720-5p/CYB5R2 axis [97], topical administrated NADPH oxidases 4 inhibitor, GLX7013114 [98], a non-steroid mineralocorticoid receptor, finerenone [99], and miRNA-124 [100]. Although there are a variety of diabetic models, including rodents and Drosophila, which are available worldwide, no ideal models of diabetic retinopathy have been established yet [101,102].…”