Purpose: The presence of eosinophilic granulocytes in ocular tissue is a hallmark of the host response to environmental and parasite allergens. Using a mouse model of Onchocerca volvulus-mediated keratitis (river blindness), the present study examined the role of the cytokines interleukin (IL)-4 and IL-13 in regulating recruitment of eosinophils to the cornea through expression of intercellular cell adhesion molecule (ICAM)-1.
Methods: C57BL/6 mice received an intrastromal injection of recombinant IL-4 and IL-13 (rIL-4 and IL-13) or were immunized by subcutaneous injection prior to receiving an intrastromal injection of a soluble O. volvulus extract. Expression of ICAM-1 and recruitment of eosinophils to the cornea were monitored by immunohistochemistry.
Results: Expression of ICAM-1 was elevated after injection of rIL-4 or IL-13 together with recombinant tumor necrosis factor (rTNF)-alpha. Conversely, expression of ICAM-1 in O. volvulus-mediated keratitis was significantly reduced after subconjunctival injection of a monoclonal antibody (mAb) to IL-4 or IL-13. In addition, combined in vivo neutralization of IL-4 and IL-13 inhibited recruitment of eosinophils, but not of neutrophils, to the corneal stroma.
Conclusions: These findings demonstrate that expression of ICAM-1 and recruitment of eosinophils to the cornea are tightly regulated by IL-4 and IL-13, and indicate that these cytokines are a potential target for immune intervention in ocular allergy and parasitic infections of the eye.