Abstract
Abstract: :
Purpose:The sensory neuropeptide substance P (SP) participates in inflammation, wound healing and maintenance of corneal health. Pterygium is a corneal disease characterized by inflammation and abnormal wound healing and since it’s shape parallels the distribution of sensory corneal nerves, we choose to investigate the role of SP in the pathogenesis of pterygium. Methods:Primary pterygium epithelial and fibroblast cultures were established from surgical tissue and characterised by flow cytometry. Migration of pterygium epithelium, fibroblasts and a human microvascular endothelial cell line (HMEC–1) was investigated using a modified Boyden chamber method. Briefly, gelatin–coated polycarbonate filters (10 to 12–µm pore size) separated the top well containing 2.5x104 cells from the bottom well containing a range of SP concentrations (10–16 to 10–4M). After 6 hours, the migrated cells were stained and counted. Results:Of the cell lines tested, SP induces chemotaxis of pterygium fibroblasts (peak concentration of 10–8M) and in microvascular endothelial cells (peak range of 10–8 to 10–6M) but no migration in pterygium epithelial cells (despite incubation to 24 hours). Cell migration to SP was mediated by the neurokinin 1 receptor (NK1R) as suggested by blockade with a specific NK1R antagonist (L732138). Conclusions:The sensory neuropeptide SP may contribute to pterygium formation by acting as a chemoattractant to pterygium fibroblasts and vascular endothelium and is a possible explanation for the triangular shape of pterygium.
Keywords: Pterygium • cornea: basic science • neuropeptides