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Cynthia Xin-Zhao Wang, Bogale Aredo, Xin Zhong, Rafael Ufret-Vincenty; Towards an understanding of the molecular basis for subretinal macrophage/microglial infiltration. Invest. Ophthalmol. Vis. Sci. 2016;57(12):6575.
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© ARVO (1962-2015); The Authors (2016-present)
Subretinal microglia/macrophages have been identified in patients with AMD and retinal dystrophies, and also in multiple animal models of retinal degenerations. Yet, there is little known about the factors that regulate their accumulation in the subretinal space, and their level/type of activation. We have previously shown that the number of yellow fundus spots have a strong correlation with the number of Iba-1+ subretinal microglia/macrophages. Our aim was to study the gene expression profile of the retina, RPE and subretinal macrophage/microglia in eyes showing many vs. few subretinal yellow fundus spots.
Age-matched aging (21-26 m old) chimeric Cfh transgenic mice vs. C57BL/6J mice were photographed using a Micron IV rodent fundus camera. Eyes were classified into 4 groups, using the genotype and a semiquantitative scale based on the density of yellow fundus spots: CfhTg/Hi, CfhTg/Lo, B6J/Hi and B6J/Lo. Eyes were enucleated and total RNA was isolated from the retina, and from the RPE/subretinal microglia. qPCR analysis of 62 candidate genes related to microglial chemotaxis, inflammation and oxidative stress was done. Additional eyes were obtained for protein isolation, and analyzed using a Luminex Cytokine Mouse Magnetic 20-Plex Panel. Finally, eyes were also collected for immunohistochemistry.
: CfhTg mice had on average a significant increase (p=0.03) in the number of yellow fundus spots compared to B6J mice. However, there was a wide range of fundus spot density in each strain of mice. The qPCR analysis revealed that 14 RPE/subretinal microglia genes were up- or down-regulated with an increased number of fundus spots in CfhTg mice (8 in B6 mice). Analysis of retina samples only revealed two genes altered in mice with a high number of subretinal spots in CfhTg mice. We were able to identify several gene families that appeared to be involved in the differential microglial subretinal infiltration. These include cytokines, chemokines and signal transduction genes. Luminex and immunohistochemistry data will also be presented.
A wide range of genes involving several pathways are differentially expressed in eyes with increased number of subretinal microglia. A better understanding of subretinal microglial behavior may lead to new therapeutic approaches for a variety of retinal diseases.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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