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Margaret Young, Marlyn P Langford, Thomas Redens, Shubnum Chaudhery; Gamma-Glutamyl Transpeptidase in Human Diabetic and Non-Diabetic Corneas. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5528.
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Diabetic keratopathy is common in longstanding diabetic cases. Failure to protect against diabetes-associated increases in oxidative stress and reactive oxygen species has been associated with diabetic keratopathy. The current investigation assesses gamma-glutamyl transpeptidase (GGT; key enzyme in the recapture of the anti-oxidant glutathione) activity in corneal epithelium of diabetic and non-diabetic human eyes.
The expression of GGT in the corneal epithelium of 10 enucleated or eviscerated eyes from 5 diabetic (3 with diabetic retinopathy) and 5 non-diabetic cases was assessed by immunohistochemical analysis.
Immunoreactive GGT was predominantly expressed by the columnar epithelial cells and flat surface epithelial cells. GGT was expressed weakly by the winged epithelial cells. GGT was concentrated in the cell and nuclear membranes of the columnar epithelial cells. Diabetic keratopathy was not detected, but thinning of the central corneal epithelium was noted and immunoreactive GGT was reduced from non-diabetic corneas in the columnar epithelial cell membranes of the diabetic eyes.
The results of these basic studies suggest diabetes-related loss of corneal GGT/glutathione recapture activity. The results are consistent with the therapeutic importance of maintaining anti-oxidant potential in cornea as well as other ocular tissues that are susceptible to diabetes-induced oxidative stress.
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