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Rozina Noristani, Sandra Kuehn, Mathias Kuehn, Jennifer E. Schiwek, Franz H. Grus, Burkhard Dick, Stephanie C. Joachim; Glia Alterations In An Experimental Autoimmune Glaucoma Model. Invest. Ophthalmol. Vis. Sci. 2012;53(14):2024.
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© ARVO (1962-2015); The Authors (2016-present)
Under pathological conditions glia cell invasion is associated with neuronal decline. Over the past decades evidences obtained from experimental studies supported the role of auto-antibodies in glaucoma which cause retinal ganglion cell (RGC) loss and glia activation. The aim was to examine if glia activity changes in retina after immunization with S100 calcium-binding protein and optic nerve homogenate (ONA).
Rats were immunized with S100 and ONA in Freund’s Adjuvant and Pertussis Toxin (n=6). Both groups were compared with NaCl as a control group (n=6). After 28 days astrocytes and RGC density was quantified in retinal cross-sections using glia fibrillary acidic protein (GFAP, Millipore) and brain specific homeobox (Brn-3a, Santa Cruz) in double staining to investigate gliosis and loss of RGC at once. Photos were taken in two central and two peripheral areas of four sections per eye. GFAP intensity was scored ranging from 0 (no signal) to 3 (severe signal) and a group comparison was performed using student t-test. Additionally, immunostaining with anti-Iba1 and anti-ED1 was performed to gain further knowledge about the role of activated microglia in retina.
A significant lower number of RGCs was detectable in ONA and S100 group after 28 days (S100: p=0.005; ONA: p=0.0005). Findings of glia cells in ONA immunized rats revealed a massive invasion of glia compared to control group. A significant difference regarding GFAP staining intensity could be observed between the ONA (mean score 2.3±0.70) and the control group (1.8±0.67, p=0.000001). The mean GFAP score in the S100 group was not significantly higher than in control group and stayed within the normal range (p=0.7).
Therefore, we conclude that the immunization with certain ocular antigens such as ONA causes gliosis which is engaged in eliciting RGC death in this model. Other antigens like S100 lead to RGC loss without significant gliosis. The severity of gliosis seems to be highly antigen-dependent. These findings indicate that the immunization with ONA causes a lower RGC density which is linked to proliferation and invasion of glia in this model.
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