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S. C. Joachim, M. B. Wax, B. Li, W. F. Holt, N. Pfeiffer, F. H. Grus; Can Immunization With Heat Shock Protein 27 Cause Retinal Ganglion Cell Loss and Antibody Profile Changes in Animals?. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5617.
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© ARVO (1962-2015); The Authors (2016-present)
Antibodies against heat shock protein 27 (HSP27) have been identified in sera of glaucoma patients in several studies. The aim of this study was to analyze if immunization with HSP27 can cause retinal ganglion cell loss in rats and analyze changes in antibody profiles.
Lewis rats were immunized with 100 µg HSP27 plus Freund’s adjuvant and pertussis toxin and euthanized after 6 weeks (n=8). Control animals that received no immunization were also euthanized after 6 weeks (n=9). Intraocular pressure (IOP) was measured in all animals (immunized and controls) before and 2 and 4 weeks after immunization. Blood was collected during different time points in this study: before immunization (0) and 2, 4, and 6 weeks after immunization. A Protein G bead approach followed by ProteinChip techniques (Seldi-TOF) was used to detect IgG antibody profiles against retinal antigens in sera. The antibody patterns were analyzed by multivariate statistical techniques. Eyes were harvested and flatmounts were stained with Brn-3a to detect retinal ganglion cell nuclei. We used a computer assisted quantitation of the retinal ganglion cell (RGC) density.
No significant changes in IOP were observed during the course of the study, no significant IOP difference could be seen between immunized and non-immunized animals. Six weeks after immunization the HSP27 group showed a lower number of RGCs comparison to controls (approx. 30% loss, P<0.05). All sera, even before immunization, showed complex IgG antibody profiles. After immunization animals showed significantly increased antibody reactivity against HSP27 and significant up- and down-regulations of antibody reactivies in other regions. Using multivariate statistical methods we could demonstrate a significant difference between antibody patterns before and 2 weeks after immunization (P=0.009) as well as between antibody patterns before and 4 weeks after immunization (P=0.0004).
After immunization with HSP27, animals developed strong antibody reactivities against HSP27, which led to significant loss of retinal ganglion cells. In glaucoma patients previous studies could demonstrate specific antibody profiles against retinal antigens. Similar to our findings in patients immunized animals did develop complex profiles against retinal antigens. Thus, immunization with ocular antigens like HSP27 might be a promising approach to understand the complex autoimmune mechanisms involved in glaucoma.
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