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Interleukin-17 and its Correlation with Vascular Endothelial Growth Factor Expression in Ocular Surface Pathologies: A Histologic Study

Purpose Interleukin-17 (IL-17), a cytokine that was recently associated with various inflammatory processes, was evaluated in ocular surface inflammatory pathologies, namely pterygium and inflamed juvenile conjunctival nevus (IJCN). Its expression was examined in correlation with vascular endothelial growth factor (VEGF) expression. Methods Expression of IL-17 and VEGF was immunohistochemically evaluated in 50 pterygia and 9 IJCN specimens. The pattern of IL-17 and VEGF expression was studied as well as the correlation between the 2 cytokines. Results Interleukin-17 was expressed in all IJCN samples and in 84% of pterygia (Fisher exact test, p<0.002). In pterygium, it was expressed mainly in the basal layer of the epithelial cells, in the perivascular tissues, and in the vascular endothelial cells. In IJCN, it was mainly expressed in the inflammatory infiltrate. In normal conjunctival epithelium, it was barely detected and was positive in only 11%. Vascular endothelial growth factor was expressed in all IJCN samples and in 92% of pterygia (Fisher exact test, p<0.002). It was expressed in the surface epithelial layers of the pterygium and in the vascular endothelium. In IJCN, it was again seen in the vascular endothelial cells and in the inflammatory infiltrate. Vascular endothelial growth factor expression was noted in 67% of normal conjunctival sections. Conclusions The present study describes the expression of IL-17 in pterygium and in IJCN. These findings provide new insights into pterygium and IJCN pathogenesis. Interleukin-17 blockade may have a potential role in management of pterygium and IJCN or preventing pterygium recurrence.