Experimental autoimmune uveitis in rabbits: clinical and functional evaluation

Abstract

Purpose: Autoimmune uveitis is an ocular inflammatory disease of unknown etiology in which the eye can be the only organ involved or can be a part of a syndrome involving multiple tissues. Several studies have been using models of experimental autoimmune uveitis (EAU), a disease model that affects specifically the eye and is mediated by T lymphocytes. However, EAU is well established in mice and rats while data in rabbits are scarce. The aim of this study is to evaluate the clinical and functional findings in the rabbit eye during the course of EAU.

Methods: EAU was induced by intravitreal injections of M. tuberculosis H37Ra antigen (Difco Lab) in 10 rabbits preimmunized with a subcutaneous injection of 10 mg of the same antigen. Fellow eye was used as control. ERG was recorded 1 day before and sequentially on the following 48 days after induction (total of 12 sessions). The ERGs were recorded according to a ISCEV protocol, which used five scotopic stimulus intensities after 30 min of dark adaptation: 0.0009; 0.009; 0.09; 0.9 and 9.0 cd.s/m² and one photopic stimuli after 2 min of light adaption: 9.0 cd.s/m2 in a background of 25 cd/m². The biomicroscopy was performed in 8 animals with slit lamp Topcon SL-3G model after each ERG session.

Results: ERG showed significant functional retinal impairments. In scotopic condition there was increase in a-wave latencies (p<0.03) and decrease in a-wave amplitudes (p<0.04). There was an increase in b-wave latency (p<0.01) and a decrease in b-wave amplitude (p<0.04). Photopic ERG showed no change in a-wave but increased implicit time 20 days after uveitis induction (p<0.02). Biomicroscopy showed that 66% of the animals had progressive moderate conjuntiva hyperemia that started on day 7 and recovered by day 35. Anterior chamber cells and flare presented the same profile but more severe. Subcapsular cataract was present in 83% of the eyes.

Conclusions: The uveitis induction promoted alterations in both a- and b-waves suggesting pre- and post-receptoral permanent retinal damage. Clinical findings showed improvement over time and indicated that the presence of cataracts is a consequence of the inflammation. Our results are in agreement with literature and indicate that this EAU model produces a limited spectrum of the disease and can be used as a self-limited model of autoimmune uveitis.