Purpose: To compare levels of isoenzymes of glutathione S-transferase (GST) and mammalian target of rapamycin (mTOR) in pterygium and normal conjunctival tissues.
Methods: This study included 28 patients who had presented to our clinic between January 2018 and June 2018 for primary pterygium, without recurrence or history of prior eye surgery, as well as 20 age-matched control patients scheduled for strabismus surgery and having no history of prior eye surgery. The entire population was of European ancestry. Brown staining of epithelial cell cytoplasm and/or nuclei was considered positive for GST isoenzymes and the mTOR protein. The intensity of staining was evaluated as follows: grade 0 (negative), grade 1 (weak), grade 2 (moderate), and grade 3 (heavy).
Results: The mean age was 53.7±1.3years in the pterygium group and 44.6±2.4years in the control group. There was no significant difference between the two groups in terms of age or sex (P>0.05). Among the 28 pterygium tissue samples, 10 (35.7%) were positive for the isoenzyme GST-Z, 15 (53.6%) for GST-S, and 10 (35.7%) for GST-K. Expression of mTOR was positive in 22 samples (75.5%). Compared to the control group, there was no statistically significant difference in levels of expression of GST-Z, GST-K or mTOR (P=0.751, P=0.749, P=1.00 respectively). No statistically significant correlation was found between the size or stage of the excised pterygium tissue and levels of expression of glutathione S-transferase sigma (GST-S) (P=0.76 and P=0.73 respectively).
Conclusion: We believe that the significant increase in expression of GST-S in pterygium serves to maintain antioxidant function against the formation of free radicals in response to exposure to ultraviolet and other factors.
Keywords: Cible mammalienne de la rapamycine (mTOR); Glutathion S-transférase (GST); Gluththione S-transferase (GST); Mammalian target of rapamycin (mTOR); Pterygium; Ptérygion.
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