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Yashar Seyed-Razavi, So-Ra Lee, Jiawen Fan, Weiyong Shen, Mark C Gillies; JR5558 transgenic mice are a reliable model to investigate subretinal fibrosis. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2253.
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© ARVO (1962-2015); The Authors (2016-present)
The development of subretinal fibrosis is a major and untreatable cause of poor outcomes in eyes with neovascular (n)AMD. JR5558 transgenic mice develop subretinal neovascularization along with subretinal hyperreflective lesions similar to areas of subretinal fibrosis seen in eyes with nAMD. This project aims to characterise JR5558 mice as a model to study subretinal fibrosis.
Colour fundus photographs (CFP) and optical coherence tomography (OCT, Phoenix Micron IV) were utilised to non-invasively track hyperreflective lesions and subretinal fibrosis from 4 weeks in JR5558 transgenic mice. The number and area of lesions in CFP was quantified in ImageJ. Fluorescein angiography was performed to investigate vascular leak. Immunohistochemistry (IHC) of retinal sections was performed with antibodies against αSMA, GFAP and CD31. Protein expression in the neural retina was assessed by Western blot and compared to age-matched controls. Data presented as mean±sem with one-way ANOVA performed to compare the data.
Analysis of CFP revealed subretinal lesions expand between 4 and 8 weeks (0.32±0.20 vs 0.41±0.23mm2, p=0.0005), becoming established in size and location around 12 weeks (0.38±0.49mm2, vs. 4wks p=0.06; vs. 8wks p=0.55). The number of lesions increased in 60% of animals between 4-8 weeks (15.2±1.5 vs. 16.6±1.1, p=0.68) and remained static at 12 weeks (16.8, p=0.99). Analysis of OCT images revealed alterations in the layers of the neural retina and underlying subretinal lesions. Retinal sections confirmed alterations in the neural retina layers and revealed Muller-glia (GFAP+) penetrate through the photoreceptor layer, becoming an integral part of the lesions at 8 weeks. Analysis of neural retina protein expression revealed a significant increase in fibronectin (4wk: 386±54%; 8wk: 357±24%, both p<0.001) at the early timepoints, while CTGF (20wks: 161±7%, p<0.001), MMP2 (12wks: 159±15%, p<0.01; 20wks: 150±15%, p=0.014) and αSMA (12wks: 188±33%, p=0.02; 20wks: 226±24%, p=0.002) significantly increased later. Increased GFAP expression (8wk: 247±30%, p<0.001; 12wk:180±6%, p=0.01) confirmed the IHC results.
Our study provides evidence that naturally occurring subretinal lesions in JR5558 mice have a fibrotic component that grows reliably and predictably between 4-8 weeks, making these mice a good model to further study the mechanisms of subretinal fibrosis and how it may be prevented.
This is a 2021 ARVO Annual Meeting abstract.
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