Abstract
Purpose: :
To investigate the tear levels of neuropeptides such as Substance P (SP), Vasointestinal Peptide (VIP), Calcitonin Gene-Related Peptide (CGRP) and Neuropeptide Y (NPY), at baseline and after allergen Conjunctival Provocation Test (CPT) in patients with allergic conjunctivitis and healthy subjects.
Methods: :
Eight patients (M, 28.90±2.00 yrs) with evidence of skin sensitivity but without ocular symptoms have been evaluated before and after CPT. Four healthy age-matched subjects (M, 29.00±0.00 yrs) were used as controls. CPT was performed with increasing concentration of specific allergen in the right eye (RE) till grade +2 of hyperemia was obtained. Balanced saline solution (BSS) was used to challenge for the controlateral eye (LE). Tears (30-50µL) were collected both at baseline and within 15min from last allergen/BSS challenge. A commercially available EIA test was used to quantify neuropeptides in normalized samples (A280-spectrophotometer analysis).
Results: :
At baseline, the tear levels of neuropeptides were not significantly different between allergic and controls (p>.05). A significant increase in tear levels of SP (p<.01), CGRP (p<.001), VIP (p<.001) and NPY (p<.001) was observed in allergic patients following challenge, when compared to baseline, unchallenged controlateral and controls. The levels of neuropeptides did not change significantly when CPT was performed in controls (p>.05).
Conclusions: :
Specific CPT resulted in an increase of all neuromediators in the tears from allergic patients while no increase was observed in control healthy subjects or in both groups upon saline stimulation. These finding suggest that neuromediator increase (neurogenic inflammation) is strengthen linked to the specific allergic stimulation.
Keywords: conjunctiva • neuropeptides • immunomodulation/immunoregulation