Handel, K. W.; Lim, J.; Iwashita, H.; Khan, S.; Shevalye, H.; Park, S.; Echeverria, N.; Ferneding, M.; Khan, M. J.; Roszak, K. P.; Donovan, G. L.; Iwamoto, M.; Shim, J.; Young, L. J.; Ardon, M.; Le, S. M.; Leonard, B. C.; Skeie, J. M.; Greiner, M.; Thomasy, S.

Col8a2Q455K/Q455K (Q455K) mice exhibit features of early-onset Fuchs endothelial corneal dystrophy (FECD), including decreased endothelial cell density (ECD) and guttae formation. Within the context of these clinical features, this study longitudinally evaluates ferroptosis in Q455K and wild-type (WT) mice using in vivo imaging, PCR and immunohistochemistry. Fifty-six Q455K and 56 WT mice were evaluated from 3 to 24 months of age with in vivo confocal microscopy; ECD and guttae were measured. Ferroptosis marker expression was determined with PCR and immunohistochemistry (IHC). Data were analyzed using two-way ANOVA with Tukeys post hoc test, Chi-square test and a paired t-test. The ECD significantly decreased in both groups from 3 to 24 months of age, but more markedly in Q455K (2285-/+317 to 1012-/+58 cells/mmSquare) versus WT mice (2714-/+139 to 2057-/+149 cells/mmSquare, P<0.0001). Guttae were observed exclusively in Q455K mice beginning at 3 months of age and increased over time (P=0.0003). The Q455K mice demonstrate guttae at the vertices of corneal endothelial cells rather than their centers (74.3% vs. 25.7%P<0.001). Expression of ferroptosis-related genes (Tfrc, Slc40a1, Ftl1, Gpx4) were significantly increased in the Q455K versus WT mice (P<0.05). Furthermore, corresponding protein expression (transferrin receptor 1, ferroportin, ferritin and glutathione peroxidase 4) was significantly elevated adjacent to guttae in Q455K versus WT mice (P<0.05). These findings implicate guttae in the initiation of ferroptosis as it relates to the pathophysiology of FECD and provide an optimal window for testing novel FECD therapies using this murine model, particularly those that target ferroptosis.