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Justin C. Kohl, Abrar A. Rageh, Deborah A. Ferrington, Sandra R. Montezuma; Effects of LMP7 Subunit Knockout Immunoproteasome on the Laser-Induced Chorioretinal Neovascular Model in Mice. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5825.
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Recent studies have shown that the immunoproteasome may be involved in the retina’s response to oxidative stress (Hussong et al., 2010). This study was performed to determine the effects of LMP7 subunit knockout of the immunoproteasome on laser-induced chorioretinal neovascularization lesions in mice.
Ten age-matched C57BL/6 wild-type (WT) mice and ten LMP7 (-/-) knockout mice were used. Four chorioretinal laser burns were placed at one disc diameter away from the optic nerve with settings of 100 milliseconds and 90 mV of current and 100 microns spot size. At one and two week time points, flourescein angiography was performed with fundus photos of the lesions using a Micron III camera and lesions were graded based on the extent of leakage. Anesthetized mice were then injected in the left ventricle with 0.1 ml of 0.5mg/ml fluorescein lycopersicon esculentum (tomato) lectin and then sacrificed after five minutes. The eyes were enucleated and chorioretinal flat mounts were performed. Scanning fluorescent laser confocal microscopy was performed with two-micron sections for each of the retinal lesions. Image J software was used to determine the volume of each laser lesion.
At one-week time post-injury, the relative volume of the lesions were 0.702 ± 0.0867 x 106 units for the WT mice and 1.091 ± 0.0974 x 106 units for the LMP7 (-/-) mice (p=0.0044). At two-weeks post-injury, the relative volume of lesions were 0.608 x 106 ± .0910 x 106 units for the WT mice and 1.566 ± 0.248 x 106 units for the LMP7 (-/-) mice. (p=0.0007). These results show that the laser lesions from LMP7 (-/-) mice had significantly more volume than WT mice at both one and two weeks post-injury.
Our results suggest that the immunoproteasome plays a protective role, since absence of the LMP7 subunit results in significantly greater laser lesions. To our knowledge, this is the first research demonstrating the importance of possessing the complete immunoproteasome complement in laser-induced chorioretinal neovascularization model.
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