Background: To investigate the expression levels of vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor 1 (VEGFR-1) and VEGFR-2 in pterygium and to clarify the prognostic significance of these expressions in pterygia.
Methods: A total of 40 surgically excised pterygia and 9 normal conjunctivae were immunohistochemically studied applying the streptavidin-biotin method in paraffin-embedded tissue sections. Monoclonal antibodies were targeted against VEGF, VEGFR-1 and VEGFR-2 proteins. At the sixth postoperative month, the recurrence rate was graded on a scale of 1-4.
Results: The mean percentage of VEGF-positive epithelial cells was comparable in pterygium and normal conjunctivae. However, the pterygium group presented higher expression levels of VEGF in pterygia endothelial cells (p=0.05). In terms of VEGFR-1 expression in epithelial cells, no statistically significant difference was found between two groups (p=0.658). However, normal conjunctivae exhibited higher expression levels of VEGFR-1 in endothelial cells (p=0.002). Epithelial cells in pterygium presented higher combined scores of VEGFR-2 (87.5% and 22.2%, respectively) (p=0.013). While higher expression levels of VEGFR-2 were documented in pterygia endothelial cells, no VEGFR-2 immunoreactivity was observed in the endothelial cells of normal conjunctivae (p<0.001). Expression levels of VEGFR-2 in epithelial cells and endothelial cells were positively correlated with the postoperative recurrence grading system (p<0.001 and τ=0.627, p=0.001 and τ=0.508, respectively).
Conclusions: The results suggest that VEGF may play a key role through VEGFR-2 in the pathogenesis of pterygium. Moreover, overexpression of VEGFR-2 in pterygia may have a predictive value for a higher postoperative recurrence rate.
Keywords: Conjunctiva.
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