Kinetics of Corneal Antigen Presenting Cells in Experimental Dry Eye Disease

To evaluate dry eye disease (DED)-induced alterations in subsets of corneal antigen presenting cells (APCs) in a mouse model of experimental DED.

Seven to 8-week-old female C57BL/6 mice were housed in a controlled environment chamber and were treated with subcutaneous scopolamine to induce DED. Normal mice were used as controls. The frequencies of different subsets of dendritic cells (DCs) and macrophages in the cornea were evaluated using immunohistochemistry and flow cytometry at days 2, 7 and 14 after DED induction. Real-time PCR was used to assess the functional phenotype of macrophages in the cornea of DED mice.

Our results demonstrated significant corneal infiltration of CD11b⁺ and CD11c⁺ cells on days 7 and 14. Further analysis of different DC subsets revealed non-significant changes in the frequencies of total CD11b⁺CD11c⁺ cells at different time points. However, frequencies of CD11c⁺CD11b^- DCs, CD11c⁺ Langerin (CD207)⁺ DCs and macrophages were significantly increased on both days 7 and 14 after DED induction. Real-time PCR data demonstrated increased expression of M1 macrophage markers, iNOS and TNF-α, and reduced expression of M2 macrophage markers, Arg1 and IL-10, by corneal F4/80⁺ macrophages at day 7.

Although the frequencies of total CD11b⁺CD11c⁺ cells do not significantly change in the course of DED, CD11c⁺CD11b^- DCs and Langerin⁺ DCs do show a significant increase. Interestingly, macrophages exhibit a predominant inflammatory M1 phenotype and suppressed anti-inflammatory M2 phenotype early after induction of DED, which are restored to near baseline levels in later stages of the disease.