Nestin expression in pterygia: potential role in angiogenesis.

OBJECTIVE: Pterygium is a common, benign fibrovascular disease of the human ocular surface that can impair vision and restrict ocular mobility if not removed. Surgical excision is the most common form of treatment; however, non-surgical therapeutics are being developed, which target the angiogenic component of this disease. Nestin is a class VI intermediate filament protein expressed in neuroepithelium with an emerging role in angiogenesis and tumourigenesis. Given the tumour-like and angiogenic features of pterygia, we postulated that nestin partakes in its development.

METHODS AND RESULTS: Formalin-fixed, paraffin-embedded pterygia and donor-matched conjunctiva (n=22) were obtained, sectioned and stained for nestin by immunohistochemistry and immunofluorescence. Immunoreactivity for nestin was semi-quantified and microvessel density counted. Significantly, higher nestin expression was identified in pterygium epithelial cells and blood vessels compared with matched normal conjunctiva. Interestingly, a high proportion of the pterygium specimens displayed nuclear staining for nestin within the basal and suprabasal epithelium. Immunofluorescence was used to simultaneously detect nestin in CD31(+) blood vessels; however, this protein was absent from Lyve-1(+) lymphatic vessels. In addition, blood and lymphatic vessel density was significantly higher in pterygia compared with corresponding control conjunctiva.

CONCLUSIONS: These results demonstrate for the first time the expression of nestin in the pterygium vasculature and indicate that this protein may play a central role in the angiogenic response, which characterises this disease. Targeting nestin pharmacologically could be considered as an alternative or adjuvant therapeutic strategy.