Analysis Of The Dynamics Of Leukocyte Accumulation In Chronic EAU

Abstract

Purpose: : Using CD4+ T cell mediated Experimental Autoimmune Uveitis (EAU) as a model for human non-infectious intraocular inflammation (uveitis) we have demonstrated temporal variation in the leukocyte populations that infiltrate the retina during retinol binding protein (RBP)-3 (previously known as IRBP) peptide induced disease. C57BL/6 EAU is a mild, chronic and persistent inflammatory condition and the environment of the inflamed eye in terms of changes in leukocyte populations during later phases of disease is not well understood. The purpose of this study was to analyse leukocyte subsets and determine what characterises the persistent inflammation.

Methods: : C57BL/6 mice were immunised with RBP-3 1-20 peptide. Disease progression was assessed by Topical Endoscopic Fundal Imaging (TEFI) and retinal infiltrate quantified by flow cytometry. Cytokine production was measured by intracellular cytokine staining. Cytotoxicity was assessed by flow cytometric CD107a expression.

Results: : EAU induced in C57BL/6 mice with RBP-3 1-20 peptide led to a chronic and persistent disease. After the primary peak of cell infiltrate, at day 25 post immunisation, there was a significant increase in the frequency of CD4+ IL-17 producing cells compared to CD4+ cells obtained from the spleen. As disease progressed, there was also a late and significant increase in the normalised number of CD8+ T cells. These cells did not express high levels of IFNγ or IL-17 and lacked the ability to degranulate, as demonstrated by negligible CD107a expression. At day 40 post immunisation we also noted a significant increase in cytotoxic CD107a+ NK cells infiltrating the retina.

Conclusions: : Analysis of retinal infiltrate in a model of chronic EAU revealed distinct changes in the composition of the infiltrating lymphocyte cell populations late in disease that may play a role in the balance of regulating versus perpetuating uveitis.

Keywords: inflammation • uveitis-clinical/animal model