Expression of Placental Growth Factor, Neuropilin-1 and Neuropilin-2 in Primary Pterygium Tissue

Abstract

Objective The aim of this study was to evaluate the expression of Placental Growth Factor (PLGF), Neuropilin-1 (NP-1) and Neuropilin-2 (NP-2) molecules in the primary pterygium tissue compared with the normal conjunctival tissue. Methods The records of 42 patients who underwent excision surgery with autograft for primary pterygium (pterygium group) and 20 patients who underwent conjunctival nevus excision surgery (control group) in the same period were reviewed retrospectively. The samples obtained from the pterygium tissues in the pterygium group, and the clean conjunctival tissues adjacent to the nevus in the control group were collected from the archive. Immunohistochemical stains of the primary antibodies: 1/100 diluted PLGF, NP-1, and NP-2 (Abcam Cambridge Science Park, UK) were applied to all groups. Staining intensities and percentage of positive cells in epithelial, endothelial, stromal, and inflammatory cells were analyzed by an experienced pathologist. Results The positivity rates of PLGF and NP-2 expression in epithelial, endothelial, stromal, and inflammatory cells were found to be higher in the pterygium group compared with the control group (PLGF: p < 0.001, p < 0.001, p = 0.001, p < 0.001, respectively; NP-2: p < 0.001, for all). Staining intensities for PLGF and NP-2 were higher in the pterygium group than in the control group (PLGF: p < 0.001, p < 0.001, p = 0.005, p < 0.001, respectively; NP-2: p < 0.001, p < 0.001, p = 0.001 and p < 0.001, respectively). However, no significant difference was found in all cell types in terms of NP-1 expression positivity rate (p = 0.730, p = 0.121, p = 0.524 and p = 0.624, respectively) and staining intensity (p = 0.716, p = 0.147, p = 0.147 and p = 0.780, respectively). Conclusion High levels of PLGF and NP-2 detected in pterygium tissue suggest that they may be future therapeutic targets in preventing pterygium progression and postoperative recurrence.