Abstract
Purpose: :
Eosinophils and thymic stromal lymphopoietin (TSLP) are increased on the ocular surface during allergic inflammation. Our previous studies demonstrated that eosinophils respond to high concentrations of TSLP with degranulation. The purpose of these studies was to examine whether priming with TNFα and IL-3 (previously shown to upregulate eosinophil TSLP receptor expression) or co-incubation with primary human conjunctival epithelial cells could affect the responsiveness of eosinophils to TSLP.
Methods: :
Eosinophils were stimulated with various concentrations of TSLP and evaluated for release of eosinophil derived neurotoxin by ELISA. For priming experiments, degranulation was evaluated in the presence and absence of pre-treatment with TNFα and IL-3. For co-incubation experiments, primary human conjunctival epithelial cells were cultured on transwell filters in 24 well plates. Eosinophils were added either apically or basally (and to epithelial cell free, control wells) and challenged with TSLP.
Results: :
Eosinophils pre-treated with TNFα and IL-3 had enhanced sensitivity to TSLP-mediated degranulation with approximately 80-fold less TSLP concentration needed to achieve comparable degranulation. Co-incubation of eosinophils with conjunctival epithelial cells reduced TSLP-mediated degranulation in both apical and basal compartments, suggesting that the response was not contact dependent.
Conclusions: :
Eosinophils exhibit enhanced responsiveness to TSLP when exposed to cytokines present in allergic inflammation. Conversely, epithelial cells may provide a stabilizing influence on TSLP-mediated eosinophil degranulation.
Keywords: conjunctivitis • inflammation • cytokines/chemokines