Interleukin-25 expression in Chronic Allergic Keratoconjunctivitis

Abstract

Purpose: : Previous reports have shown the roles of interleukin-25 (IL-25) for atopic diseases. We investigated the expression of IL-25 in the giant papillae obtained from vernal keratoconjunctivitis (VKC) and atopic keratoconjunctivitis (AKC) patients, and analyzed its functional roles.

Methods: : IL-25, IL-17RB and IL-17RA mRNA expression was examined using the resected conjunctival samples obtained from 5 VKC/AKC patients and 5 controls by reverse transcription-polymerase chain reaction and real time PCR analysis. Anti-IL-25 and anti-IL-17RB immnunohistochemical staining was performed with nine resected giant papillae. The human conjunctival epithelial cells were stimulated with papain (cysteine protease) to examine IL-25 mRNA expression. Primary human peripheral blood derived monocytes (PBMC) were stimulated with recombinant IL-25 (rIL-25) and then IL-13 mRNA expression was quantified.

Results: : All 5 VKC/AKC samples showed significantly higher IL-25 mRNA expression compared to the control conjunctivae. IL-17RB (IL-25 receptor) expression was observed in giant papillae tissue, PBMC and eosinophils. Anti-IL-25 immunohistochemical staining showed preferential expression in the epithelial cells and some infiltrated cells of the giant papillae. Double immunohistochemical staining with anti IL-17RB antibody and CD68 antibody showed IL-17RB expression in macrophages. Papain stimulation induced IL-25mRNA expression peaked at 12 hour post stimulation, and IL-25 stimulated PBMC showed IL-13 mRNA expression.

Conclusions: : Allergen (papain) stimulation could induce IL-25 expression in the conjunctival epithelium. IL-25 protein produced in conjunctival epithelial cells play some roles for severe ocular allergy through the activation of macrophages.

Keywords: conjunctivitis • inflammation