Multimodal Evaluation of Immune-Vascular Interaction of Experimental Autoimmune Uveitis

Abstract

Purpose : To characterize the vascular phenotypes of an experimental autoimmune retinal uveitis (EAU) model induced by interphotoreceptor retinoid-binding protein (IRBP) using multimodal imaging techniques.

Methods : We systemically administered IRBP or vehicle to adult C57BL/6 mice. Fundus photography, optical coherence tomography (OCT), in vivo live confocal imaging using different tracers, blood flow analysis by OCT angiography (OCTA), and electroretinogram (ERG) were performed after IRBP immunization. Hematoxylin and eosin and immunofluorescent staining were performed to characterize the immune reaction and vascular permeability. Cx3cr1-GFP mice (microglia-reporter mouse) and LysM-GFP mice (neutrophil-reporter mouse) were used for immune cell phenotyping.

Results : EAU mice exhibited perivascular inflammation, vitritis, and superficial retinal inflammation on fundus photography and OCT. H&E revealed immune cell infiltration in the perivascular area of the retina and choroid accompanied by a significant degree of peri-vasculitis that subsequently damaged the photoreceptors 3 weeks post-immunization. Immunofluorescent staining showed subsequent transcytosis induction after local microglial activation followed by neutrophil recruitment at the perivascular area. Transcytosis in the superficial and deep vascular areas was improved by suppressing immune cells (anti-Ly6C- induced neutrophil inhibition and minocycline-induced microglial inhibition). Intravital in vivo confocal imaging showed signs of neutrophil infiltration and obstructive vasculitis with perivascular leakage 3 weeks post-immunization. OCTA revealed a significant decrease in vascular flow in the deep capillary layer of the retina. Function analysis showed that scotopic responses were intact in 2 weeks; however, normal photopic and scotopic responses were hardly detected in EAU mice 3 weeks post-immunization.

Conclusions : Our data suggest that inflammatory cell activation and subsequent transcytosis induction in endothelial cells might be a major pathogenic factor for vascular leakage in uveitis, bring new insights into the pathophysiology of retinal vasculitis in non-infectious uveitis.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.