Progression of Col8a2Q455K Corneal Dystrophy in Male and Female Mice

Abstract

Purpose : Fuchs Endothelial Corneal Dystrophy (FECD) is more prevalent in woman vs men. Mouse models of corneal endothelial dystrophy are needed to study this sex difference. The Col8a2 Q455K Knock In model produces all the hallmarks of FECD except corneal edema. We examined potential sex differences in progression of the dystrophy and potential reasons for the lack of corneal edema.

Methods : Col8a2Q455K/+ mice were bred to obtain littermates Col8a2 +/+ (WT), Col8a2 KI/+ and Col8a2 KI/KI (KI/KI). We measured corneal thickness (CT), endothelial cell density (ECD), and guttae density at 1, 3, and 5 months of age. CT was measured by OCT (Optovue). ECD and guttae density were calculated from HRT3-Rostock Cornea Module confocal microscope images. Mitochondrial Reactive Oxygen Species (MitoROS) was measured with MitoSOX, stromal lactate with a fluorescent kit and lactate transporter proteins with Protein Simple Jess at 5 months.

Results : There were no differences in CT, ECD, or guttae density between WT and KI/KI or between KI/KI males and females at 1 and 3 months and no differences between male and female WT mice at all ages. However, at 5 months CT of all KI/KI mice was slightly lower than WT littermates (KI/KI: 112.83 ± 6.76 µm (n=16) vs WT: 120.04 ± 6.27 (n=18), p=0.0053), while there was no difference between female and male KI/KI mice (female: 109.56 ± 10.06 µm (n=6) and male: 114.80 ± 2.11 (n=10), p=0.61). At 5 months ECD significantly decreased in KI/KI mice vs WT (KI/KI: 1229.53 ± 320.23 Cells/mm² (n=16) vs WT: 2180.57 ± 162.26 (n=14), p<0.0001), however not significantly different between KI/KI females 1243.95 ± 293.09 Cells/mm² (n=8) and KI/KI males 1215.10 ± 365.19 (n=8), p>0.99. Guttae density increased significantly in KI/KI mice vs WT at 5 months (KI/KI: 125.31 ± 47.65 Guttae/mm² (n=16) vs WT: 4.46 ± 6.66 (n=14), p<0.0001). Guttae density was significantly lower in KI/KI females vs males (female KI/KI: 104.38 ± 50.83 Guttae/mm² (n=8) and male KI/KI: 146.25 ± 35.78 (n=8), p=0.002). There was no difference in MitoROS between WT and KI/KI mice. Expression of lactate transporters (MCT1, 2, and 4) and corneal [lactate] were also not significantly different between WT and KI/KI.

Conclusions : In the Col8a2 KI model, the phenotype is slightly more pronounced in males vs females by 5 months of age. The lack of oxidative stress and deficiencies in lactate transport explain the lack of corneal edema in this model.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.