Abstract
Purpose: :
An in vivo mouse model has been developed that reproducibly induces recurrent epithelial erosions in wild-type mice spontaneously within two weeks after a single 1.5 mm corneal debridement wound created using a dulled blade. Using a rotating burr rather than a dulled blade creates a corneal wound that heals well with few erosions. This study was conducted to determine whether different numbers and classes of immune cells are recruited into the cornea 6 hours after wounding with either the dulled blade or rotating burr.
Methods: :
A 1.5 mm area of corneal epithelial cells was removed from the corneal surface of adult C57Bl6 mice using either a dulled blade or rotating burr. Corneas (n=12) were allowed to heal in vivo for 6 hr. After sacrifice, corneas were dissected and cells released by incubation with collagenase. Cells were also obtained from unwounded corneas (n=16). Cells were incubated with antibodies against different immune cell surface markers and flow cytometry was performed. Experiments were repeated twice. Corneas were also fixed and used for whole mount immunofluorescent studies.
Results: :
Data show that there are more total CD45+ cells recruited into the cornea within 6 hours after dulled blade wounds. Relative to unwounded corneas, there were 30 fold more monocytes (CD45+/ Ly6C hi/ Ly6G+/ CD11b hi/ F480 low/ CD11c+) recruited after rotating burr wounds compared to 47 fold more after dulled blade wounds compared to controls. There were also 2.9 fold more γΔ T cells (CD45+/GL3 hi) recruited after rotating burr wounds compared to 5.2 fold more after dulled blade wounds. No significant changes relative to control were observed in PMNs (CD45 lo/ Ly6G hi).
Conclusions: :
Within 6 hours of wounding, both rotating burr and dulled blade wounds induced recruitment of monocytes with interesting phenotypes. Flow cytometry revealed that these monocytes express little F480 on their surface but abundant Ly6C, CD11c, and are positive for Ly6G suggesting that they may be DC precursors. These data indicate differences in the early immune responses of the mouse cornea to dulled blade wounds which resolve poorly compared to rotating burr wounds that heal with few erosions. Future studies will assess whether these changes are accompanied by differences in cytokines and if they persist at longer time points.
Keywords: cornea: epithelium • wound healing • immunomodulation/immunoregulation