Abstract
Purpose:
γδ T cells responding to corneal abrasion in mice express receptors for Interleukin-23 (IL-23) and chemokine ligand 20 (CCL20). The current work assesses the influence of IL-23 and CCL20 on epithelial and sensory nerve regeneration in a murine model of corneal injury.
Methods:
Central corneal epithelial abrasion (2 mm) was performed in female C57BL/6 mice and γδ T cell-deficient (TCRδ-/-) mice. Wildtype mice received anti-IL-23 and anti-CCL20, and TCRδ-/- mice received recombinant IL-23 (rIL-23) and recombinant CCL20 (rCCL20) dissolved in PBS topically on the wounded corneas every 4 hours for 24 hours. The control animals received an equal concentration of IgG in PBS or PBS alone. Corneas were analyzed for epithelial cell division by immunofluorescence at 24 hrs post wounding. Nerve regeneration was evaluated using fluorescence deconvolution microscope to assess each field of view (150×150µm) across the cornea from limbus to limbus with a deconvolved z-stack (0.2-µm steps) encompassing the corneal epithelium, the subbasal nerve plexus, and an adjacent portion of the corneal stroma.
Results:
Dividing epithelial cells in wild-type mice had a 15.2% and 39.2% decrease after topical treatment of anti-IL-23 and anti-CCL20 (p<0.01, n=6). TCRδ-/- mice exhibited marked depression of epithelial division at 24 hours after injury, and treatment of TCRδ-/- mice with rCCL20 elevated epithelial division 28.4% (p<0.01, n=6) while rIL-23 had no effect. Early nerve regeneration is evident at 24 hours after injury, and wounded wildtype corneas after topical treatment with anti-IL-23 and anti-CCL20 had 51.0% and 31.4% reductions in nerve regeneration at 24 hours after injury, respectively (p<0.01, n=6). Nerve regeneration is significantly depressed in TCRδ-/- mice (Zhijie Li et al. Am J Path, 2011), but increased 27.2% (p<0.01, n=6) in TCRδ-/- mice after topical treatment with rCCL20. In contrast, rIL-23 treatment did not significantly increase nerve regeneration of TCRδ-/-mice.
Conclusions:
IL-23 appears to act in corneal wound healing through the γδ T cells, while CCL20 appears to have a broader range of activity.
Keywords: 480 cornea: basic science •
557 inflammation •
554 immunohistochemistry