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Sabrina Reinehr, Jacqueline Reinhard, Susanne Wiemann, Gesa Stute, Andreas Faissner, Burkhard Dick, Stephanie C Joachim; Alterations of extracellular matrix proteins in an immune mediated glaucoma model. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2430.
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© ARVO (1962-2015); The Authors (2016-present)
The extracellular matrix (ECM) forms a complex network of glycoproteins and proteoglycans. Previous studies indicate that retinal injury is accompanied by remodeling of the ECM. Here, we investigated the role of ECM remodeling in an autoimmune model of glaucoma. It is known, that a retinal ganglion cell (RGC) loss occurs in this model after 4 weeks.
Rats were immunized with optic nerve homogenate (ONA) or S100 protein. The control group (Co) received sodium chloride. Cross-sections of the retina (7+14 days) and optic nerve (ON; 3, 7, 14 days) were stained with anti-tenascin-C (KAF14) and anti-phosphacan (473HD; n=4-6/group). The staining area was evaluated via ImageJ. Statistic was performed using t-test (Statistica). At days 7 and 14 retinas were used for quantitative rt-PCR of tenascin-C and phosphacan expression (n=3/group). Data were analyzed using REST-software.
At 7 and 14 days, the tenascin-C immunoreactivity was significantly higher in ONA retinas compared to Co (7 d: Co: 17.8%±12.5, ONA: 39.9%±14.9; p=0.02, 14 d: Co: 28.7%±6.1; ONA: 39.2±6.0; p=0.04). No changes were noted in S100 retinas at 7 (p=0.2) and 14 days (p=0.1). In contrast, tenascin-C expression was significantly higher in ON of ONA and S100 animals, already at 3 days (ONA+S100: p=0.02). At day 7 the higher expression continued in the S100 group (p=0.047) and went to normal level at 14 days (S100: p=0.14; ONA: p=0.08). Expression of phosphacan significantly increased in ONA retinas at day 7 (Co: 2.2%±1.2, ONA: 11.3%±5.1; p=0.002) and day 14 (Co: 4.2%±2.4, ONA: 25.7%±18.0; p=0.03). No changes were observed in S100 retinas (7 d: p=0.3; 14 d: p=0.09). The immunoreactivity in the ONs did not alter at 3 days, but significantly increased at day 7 in the ONA (p=0.002) and S100 group (p=0.01). The high immunoreactivity continued in both groups to day 14 (ONA: p=0.01; S100: p=0.03). According to protein levels, a 1.5 (S100) to 2.3 fold (ONA) higher expression of the phosphacan mRNA level was noted at day 14 (ONA: p=0.02; S100: p=0.005).
In the autoimmune glaucoma model, remodeling of ECM components occurred shortly after immunization. The immunoreactivity of tenascin-C and phosphacan changed initially in the optic nerves. In the retinas, upregulation of tenascin-C and phosphacan started 7 days after immunization. The alteration of ECM components indicates a gliosis and may act as an early indicator in glaucoma disease.
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