The neurotrophin receptor p75^NTR as a new player in the development of choroidal neovascularization

Abstract

Purpose : Choroidal neovascularization (CNV) is a key feature in the wet form of age related macular degeneration (AMD). Current treatments are inefficient, therefore a better understanding of the pathophysiology of AMD is necessary to develop novel therapeutic approaches. The p75 neurotrophin receptor (p75^NTR) is recognized as one of the main surface proteins involved in the transduction of death signals and recently also vascular changes. Here, we aim to determine if p75^NTR participates in the development of neuronal and vascular alterations in a mouse model of laser-induced CNV.

Methods : Briefly, mice were anesthetized and their pupils were dilated, then 4 injuries were performed in the retina using a photocoagulation laser with a 532nm wavelength slit lamp. 7 days after laser mice were subjected to electrorretinography (ERG) studies, and posterior sacrifice. Retinas and RPE-Choroid were processed separately for Western blot and immunofluorescence assays in whole mounts and criosections. Colocalization was analysed in tissues double labeled with p75^NTR and one of the following cell markers: F4/80 (macrophages), NG-2 (pericytes), Isolectin IB-4 (blood vessels), glial fibrillary acid protein (glial cells) or β-actin (neurons). WT (N=17) and p75^NTR KO (N=12) mice were included in the experimental design and animals without CNV were used as control. GraphPad Prism program was employed for statistical analysis and one way ANOVA or t-test analysis was performed accordingly.

Results : In WT rodents, Western blot of neural retinas of CNV mice exhibited an increased expression of p75^NTR protein levels respect to control (p<0,05). Confocal images showed overexpression of p75^NTR in macrophages in the RPE-Choroid, and in Muller glial cells around the injured area in the retina. These alterations in the CNV model were accompanied with neuronal dysfunction observed as a reduction in the amplitude of the a-wave by ERG, which was preserved in p75^NTR KO mice. In accordance, p75^NTR KO mice showed a reduction in the area and perimeter of choroidal neovessels (p<0,05) as well as a decreased macrophage infiltrate by immunostaining.

Conclusions : Altogether these preliminary findings suggest that p75^NTR would participate in the development of CNV.

This is a 2021 ARVO Annual Meeting abstract.