Role of macrophages in the course of an in vivo murine model of Anterior Ischemic Optic Neuropathy

Purpose Anterior Ischemic Optic Neuropathy (AION) is a common cause of vision loss and is characterized by degeneration of the optic nerve and retinal ganglion cells. Recently, inflammation has been proposed to play a role in the course of AION, and we wanted to investigate the contribution of circulating and/or resident microglia. Methods We examined the role of macrophages in the course of AION, employing an in vivo murine model of laser-induced AION. AION was induced in BALB/c mice and three and six days after, OCT was performed and the number of infiltrating cells in the vitreous body was quantified. Bone marrow chimeras were generated using bone marrow derived cells that express GFP under the promoter of CX3CR1, specifically labelling macrophages. Cells were injected intravenously in lethally irradiated BALB/c mice which were subjected to AION two weeks later. Three and seven days after the AION induction, the eyes were subjected to OCT. The mice were euthanized at day 7 and their eyes were prepared for immunohistochemical studies against GFP and Iba-1. FACS analysis of the retina was also performed in AION subjected BALB/c mice 3, 7 and 14 days after AION induction. Results Three and six days after AION induction, quantification of the OCT data showed a statistically significant elevation of infiltrating cells in the vitreous of AION subjected eyes compared to control eyes. This finding was substantiated by FACS analysis. The chimeras experiments revealed infiltration of circulatory macrophages into the retina. Conclusions Our data support a role of circulating and/or resident macrophages in the course of AION.