Peroxiredoxin I and II in Human Eyes: Cellular Distribution and Association with Pterygium and DNA Damage

Peroxiredoxin I and II are both 2-Cys members of the peroxiredoxin family of antioxidant enzymes and inactivate hydrogen peroxide. On western blotting, both enzymes appeared as 22-kD proteins and were present in the sclera, retina and iris. Immunohistochemistry showed strong cytoplasmic labeling in the basal cells of the corneal epithelial layer and the corneoscleral limbus. The melanocytes within the stroma of the iris and the anterior epithelial cells of the lens also showed strong cytoplasmic labeling. The fibrous structure of the stroma and the posterior surface of the ciliary body were also labeled. There was also strong labeling for both enzymes in the photoreceptors and the inner and outer plexiform layers of the retina. There was increased labeling of peroxiredoxin I and II in pterygium. In normal conjunctiva and cornea, only the basal cell layer showed labeling for peroxiredoxin I and II, whereas, in pterygia, there was strong cytoplasmic labeling in most cells involving the full thickness of the epithelium. Co-localization of the DNA oxidation product 8-hydroxy-2'-deoxyguanosine antibody with the nuclear dye 4',6'-diamidino-2-phenylindole dihydrochloride indicated that the majority of the oxidative damage was cytoplasmic; this suggested that the mitochondrial DNA was most affected by the UV radiation in this condition.