Expression of neurotrophic factors in human primary pterygeal tissue and selective TNF-α-induced stimulation of ciliary neurotrophic factor in pterygeal fibroblasts

Pterygium is a degenerative, fibrovascular and hyperplastic growth resulting from a proliferative tissue actively growing from altered limbal stem cells at the corneal-conjunctival junction. However, the pathogenesis of pterygium is still unclear. The aim of this study was to determine the expression of neurotrophic factors (nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), and neurotrophin (NT)-3, NT-4/5) in pterygeal tissue and to confirm whether tumor-necrosis factor-alpha (TNF-α) modulates the expression of these neurotrophic factors in primary cultured pterygeal fibroblasts. We looked for expression of these neurotrophic factors in surgically excised pterygia and normal donor limbal tissues by immunohistochemistry and in primary cultured pterygeal and normal subconjunctival Tenon's fibroblasts by Western blot and reverse transcription-polymerase chain reaction (RT-PCR). Expression of CNTF and NT-4/5 is increased in pterygeal tissues compared with normal tissue, and production of CNTF is stimulated in pterygeal fibroblasts by TNF-α but not in normal fibroblasts. This selective stimulation of CNTF in pterygeal fibroblasts suggests that CNTF may play a role in the pathogenesis of pterygium.