Abstract
Purpose :
The mechanism of ocular pathology in Alport syndrome is currently not well understood. Therefore, this study characterizes the ocular features by comparing retinal and corneal thicknesses and collagen α3 (IV) protein distribution in the eye among wild-type (WT) and COL4A3 knockout (KO) mice.
Methods :
Col4a3tm1Dec mice were euthanized at 25 weeks, and eyes were processed for paraffin sectioning. The sections were stained with hematoxylin and eosin (H&E) for retinal and corneal thickness assessments. Retinal measurements were taken at 6 sites above and below the optic nerve, and the average retinal thickness was recorded. 6 WT (4 male, 2 female) and 5 KO (3 male, 2 female) retinal sections were included. Corneal sections that were undamaged and unobstructed by the lens were included. Corneal measurements were taken at 6 locations in the central cornea, and the average central corneal thickness (CCT) was calculated. 7 WT (5 male, 2 female) and 6 KO (3 male, 3 female) corneal sections were included. The difference in means was evaluated using an independent samples t-test. Samples were stained with 1:200 anti-α3 (IV) antibody, 1:2000 secondary antibody, and DAPI and viewed under a confocal microscope to visualize the distribution of α3 (IV) protein in the retina and cornea.
Results :
In literature, temporal retinal thinning has been observed in Alport eyes. Our study did find some decrease in retinal thickness, but this difference was statistically insignificant (p=0.537, nWT=6, nKO=5). Corneal thickness was marginally increased in Alport eyes; however, this difference was statistically insignificant (p=0.339, nWT=7, nKO=6). Retinal staining of the α3 (IV) protein revealed no positive staining. Corneal staining revealed positive staining in Descemet’s membrane, which anchors the endothelium to the rest of the cornea.
Conclusions :
A significant retinal and corneal thickness change in COL4A3 KO mice was not observed. The limited sample size in this study necessitates further investigation with more sections to expand upon these initial findings. Staining of ocular sections only showed positive staining in Descemet’s membrane. Additional work evaluating changes in inflammatory cytokines caused by a degradation of corneal endothelium integrity, as well as biomechanical changes in the cornea caused by the lack of the α3 (IV) protein, is necessary to better characterize the pathology of Alport syndrome.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.