Abstract
Purpose :
To investigate the localization of γ-glutamyltranspeptidase (GGT; catalyzes the cleavage of extracellular glutathione key to antioxidant homeostasis) with glutamate and cystine transporters (essential to glutathione synthesis), and biomarkers of oxidative cell death in diabetic and non-diabetic corneas from human enucleated blind-painful eyes.
Methods :
Corneas (7 diabetic and 8 non-diabetic) were analyzed by immunostaining for GGT, cystine/glutamate exchanger (Xc- antiporter) and excitatory amino acid transporter-3 (EAAT-3) (recapture glutathione), aldose reductase (hyperglycemic response), 8-OHdG (8-Oxo-2'-deoxyguanosine is an oxidized derivative of deoxyguanosineoxidized DNA), GADD45 (growth arrest and DNA damage-inducible stress protein), and annexin V (binds to phosphatidylserine, a marker of apoptosis when expressed on the outer leaflet of the plasma membrane).
Results :
GGT negative flat wing cell layer were detected between GGT positive columnar and surface epithelial cells. Decreased columnar epithelial cell GGT, Xc- antiporter and EAAT-3 expression was detected in 86% of diabetic and 25% of non-diabetic corneas. Nuclear and cytoplasmic GGT labeling was detected in undifferentiated transitional columnar cells in 75% of non-diabetic and 71% of diabetic corneas. GGT expression was reduced in diabetic cornea epithelial cells (p=0.04). GGT and 8-OHdG positive corneal columnar epithelial cells were detected in all corneas. AR positive columnar cells were detected in 6 of 7 diabetic corneas. Flat surface epithelial cells, but not columnar cells, expressed GADD45, Xc- antiporter, EAAT-3 and Annexin V.
Conclusions :
The results support increased corneal epithelial thickness due to columnar cells failure to differentiate into wing cells (consistent with corneal epithelial cells swelling). AR was detected in diabetic columnar cells. The dedifferentiated columnar cells expressed GGT and 8-OHdG, but not EAAT-3. xCT and 8-OHdG were associated with annexin V expression in the flattened surface epithelial cells.
This is a 2020 ARVO Annual Meeting abstract.