EXPRESSION OF NERVE GROWTH-FACTOR RECEPTORS ON THE OCULAR SURFACE IN HEALTHY-SUBJECTS ACID DURING MANIFESTATION OF INFLAMMATORY DISEASES

PURPOSE. Recent studies have suggested the involvement of nerve growth factor (NGF) in the conjunctival inflammatory process and in corneal epithelium proliferation and differentiation. To verify the hypothesis that NGF could locally modulate the inflammatory and reparative proce sses, the authors evaluated the expression of NGF high-affinity recept or on the ocular surface in normal and pathologic conditions. METHODS. Ten conjunctival byopsies (obtained from three healthy subjects, five patients affected by vernal keratoconjunctivitis [VKC], and two patie nts with cicatricial pemphigoid [CP]) and five corneal specimens obtai ned from the Eye Bank of Veneto (Italy) were evaluated. All specimens were histologically stained, and immunohistochemistry was performed to identify the NGF high-affinity receptor (TrkA). RESULTS. All tissues expressed immunoreactivity for NGF receptors. In conjunctival specimen s of healthy subjects, basal epithelial cells strongly expressed immun oreactivity and, in the stroma, rare cells were immunopositive for Trk A. No significant difference in immunoreactivity was observed in the c onjunctival epithelium between healthy subjects and patients with infl ammatory conjunctival diseases, whereas there were more immunopositive cells observed in the conjunctival stroma of VKC and CP patients than in the controls. The immunoreactivity in the cornea TV:LS confined to basal epithelial cells and endothelium. CONCLUSIONS. The NGF receptor is present on the human ocular surface. The authors' data support the possibility that NGF modulates ocular inflammation and corneal epithe lial proliferation and differentiation through its receptors.