Abstract
Abstract: :
Purpose: In order to test the hypothesis that autoantibodies can cause glaucoma, we sought to develop an animal model of experimental autoimmune glaucoma in rats elicited by immunization with heat shock protein27 (hsp27). Methods: Animals were divided into 3 groups: control, those receiving a single 200 microgram immunization of LPS two weeks prior to hsp27, and those receiving sham (BSS) immunization. For hsp27 immunization,100 microgram of stable emulsion containing 100 microgram of hsp27, prepared by mixing equal volumes of incomplete Freund,s adjuvant and the antigen, were used. Purified pertussis toxin at a concentration of 1 microgram per animal was used as an additional adjuvant. One and four months after immunization, eyes from Lewis rats were cut along the ora serrata, and the posterior eyecup was immersed and fixed in 4% parafolmaldehyde for 30 minutes. The retina was isolated from the eyecup and incubated in monoclonal antibodies against the protein encoded by the POU-domain genes known to be expressed by most ganglion cells across a variety of mammalian species.Vital staining was confirmed by Yoyo-1. We utilized computer assisted quantitation of ganglion cell density plotted as a function of eccentricity from the fovea in order to quantiate retinal ganglion cell loss. Results: Apoptotic retinal ganglion cell death in immunized retinas from LPS-treated Lewis rats one month after immunization with hsp27 demonstrated degenerating neurons with distended cell bodies and irregular nucleus in the retinal ganglion cells layer. Retinal ganglion cell density was compared between control and hsp27 plus LPS treated eyes (t test, <0.05, n=6). At four months following immunization with hsp27, the most prominent retinal ganglion cell loss (∼25%) occurred in the region immediately adjacent to the area centralis. This is exactly the region thought to be most affected in patients with normal pressure glaucoma. Conclusion: The results show that our model of experimental autoimmune glaucoma in rats is effective, provides a robust signal for analysis and appears highly relevant to human glaucoma.
Keywords: 316 animal model • 435 immunomodulation/immunoregulation • 415 ganglion cells