Pterygium is a surface ocular lesion that is associated with chronic UV exposure. The primary effect is a solar actinic elastosis within the stroma. All the other changes are secondary.
Pterygium is characterized by proliferation, inflammatory infiltrates,
fibrosis, angiogenesis and extracellular matrix breakdown. The aim of this study was to correlate microvascular density and
nerve growth factor (
NGF)/
NGF-receptor transmembrane
tyrosine kinase (TrkA) expression in endothelial cells in human
pterygium. Specimens of human
pterygium obtained from 30 patients who had undergone surgical excision and of 10 normal bulbar conjunctiva were investigated immunohistochemically by using anti-CD31, anti-
NGF and anti-TrkA
antibodies. Results showed that endothelial cells in human
pterygium are immunoreactive to both
NGF and its
receptor TrkA, and that this immunoreactivity is correlated to microvascular density. The results of this study suggest that an autocrine loop between
NGF and its
receptor TrkA is activated in
pterygium and that it is involved in the angiogenic response taking place in this pathological condition. These data are in accord with recent evidences, which have clearly established that
NGF plays a role as an
angiogenic factor in several pathological conditions. Understanding the mechanism of angiogenesis in
pterygium provides a basis for a rational approach to the development of anti-angiogenic
therapy in patients affected by this disease.