Abstract
Purpose:
Eosinophils and their catabolic mediators are major features in the pathogenesis of allergic conjunctivitis, contributing to corneal damage in chronic disease. The prostaglandin, PGD2, which is released from activated mast cells, has recently been shown to promote eosinophil chemotaxis. The purpose of this study was to further examine the effects of PGD2 on activation of eosinophil pro-inflammatory processes (chemotaxis, degranulation, phosphorylation of spleen tyrosine kinase [Syk] and survival/viability).
Methods:
Human purified peripheral blood eosinophils were obtained using negative immuno-magnetic bead selection. For most experiments, PGD2 was added at concentrations ranging from 0.1 - 1000 nM. For chemotaxis, eosinophils were added to the top compartment of 5.0 µm Transwell chambers, with either media or PGD2 added to the bottom for 1 hr after which eosinophils migrating to the bottom compartment were counted. For degranulation, eosinophils were stimulated with media or PGD2 for 4 hrs and supernates were harvested and evaluated for eosinophil derived neurotoxin using commercial ELISA. Flow cytometry was used for evaluation of Syk-phosphorylation, and trypan blue exclusion was used for evaluation of survival.
Results:
Stimulation of eosinophils with PGD2 promoted chemotaxis (1.0 - 100 nM, n=6 subjects, p<0.05), and trended toward promoting degranulation (10, 100 nm, n=4 subjects, p=0.1) and phosphorylation of Syk (100 nM, n=2 subjects), but not survival or viability (n=3 subjects).
Conclusions:
PGD2-mediated activation of eosinophils could play a role in eosinophil mediated processes in allergic conjunctivitis and, thus, presents a potential target for therapeutic intervention.
Keywords: 474 conjunctiva •
557 inflammation •
714 signal transduction