Altered expression of neurotransmitter receptors and neuromediators in vernal keratoconjunctivitis.

Background: There is growing evidence that autonomic innervation is involved in the pathogenesis of mucus hypersecretion, goblet cell hyperplasia, and conjunctival hyperreactivity. Objective: To determine the expression of neurotransmitters and neurotransmitter receptors in vernal keratoconjunctivitis (VKC) tissues to evaluate whether neurogenic inflammation plays a role in this ocular atopic-related disorder. Methods: Biopsy specimens of upper tarsal conjunctiva from 8 VKC patients with active inflammation and from 4 healthy subjects were processed for immunohistochemistry using anti-M 1, anti-M 2, and anti-M 3 muscarinic receptors; β 1-adrenergic receptor; vasoactive intestinal peptide; nerve growth factor; and protein gene product 9.5, a marker of nerve fibers. Results: In the conjunctival epithelium of VKC patients, M 1 muscarinic receptor, nerve growth factor, and protein gene product 9.5 expression were decreased, whereas M 2 and M 3 muscarinic receptors and β1-adrenergic receptor were irregularly distributed, compared with control subjects. Neurotransmitter receptors and vasoactive intestinal peptide expression were increased in the substantia propria-localized infiltrate of VKC compared with healthy tissue. Nerve growth factor and protein gene product 9.5 staining was also enhanced in the conjunctival stroma of VKC vs healthy conjunctiva. Conclusions: The inflamed conjunctiva of VKC patients demonstrated an obvious alteration in muscarinic and β 1-adrenergic receptor, vasoactive intestinal peptide, protein gene product 9.5, and nerve growth factor expression. These results substantiate the involvement of an autonomic dysfunction in the pathogenesis of VKC. ©2006 American Medical Association. All rights reserved.