VIP Immunoreactivity in Human Aqueous Humor

Abstract

Purpose: To demonstrate the presence of vasoactive intestinal peptide (VIP)-immunoreactive molecule in the human aqueous humor collected from eyes undergoing either cataract or glaucoma surgeries and to identify the masses of molecules responsible for the VIP immunoreactivity. Methods: Aqueous humor specimens were collected by parencentesis from nine cataract patients and also from eight patients undergoing glaucoma surgery following the creation of the limbal based conjunctival flap, partial dissection of the scleral flap, and application of mitomycin-C. The aqueous humor specimens were analyzed by radioimmunoassay to determine the level of VIP immunoreactivity. Specimens from 10 other cataract patients were pooled and analyzed for VIP immunoreactivity by Western blot analysis.Results: Levels of VIP immunoreactivity in aqueous humor of cataract and glaucoma patients were significantly different and were 610 ± 160 and 260 ± 64 pg VIP/ml, respectively (p = 0.03), while there was no correlation between the donor age and the level of VIP immunoreactivity. VIP immunoreactivity was detected as a single molecule with a molecular weight of 9000. Conclusions: The disease status and the treatments of the eye that led to surgery and procedures applied to the eye immediately before aqueous humor collection, but not the age of the patients, affected the level of VIP immunoreactivity in the aqueous humor. The relationship between the 9000 Da VIP-immunoreactive molecule and the authentic (3326 Da) VIP remains to be studied.

KEYWORDS:

• aqueous humor
• corneal endothelial cells
• immunoblotting
• neuropeptides
• trophic factors