Stratification of Antigen-presenting Cells within the Normal Cornea

Area of Science:

• Immunology
• Ophthalmology
• Cell Biology

Background:

• The cornea was historically considered immune-privileged and lacking antigen-presenting cells (APCs).
• Recent findings indicate the cornea harbors a diverse network of bone marrow-derived cells.
• Understanding the precise location and types of these cells is crucial for corneal immunity.

Purpose of the Study:

• To investigate the stratification and characteristics of antigen-presenting cells (APCs) within non-inflamed murine corneas.
• To map the distribution of dendritic cells (DCs) and other myeloid cells in the cornea.
• To elucidate the potential immune functions of these stratified corneal cells.

Main Methods:

• Utilized transgenic mice expressing enhanced green fluorescent protein (EGFP) under the CD11c promoter (pCD11c).
• Employed immunohistochemical staining to identify and localize cell populations.
• Analyzed the expression of MHC class II and CD11b markers on corneal cells.

Main Results:

• A distinct stratification of bone marrow-derived cells was observed in murine corneas.
• pCD11c(+) dendritic cells (DCs) were found in the basal epithelium, expressing MHC class II.
• pCD11c(-) CD11b(+) putative macrophages and MHC class II(-)pCD11c(-) CD11b(+) cells were located deeper in the stroma.

Conclusions:

• The cornea possesses a layered arrangement of immune cells, including APCs and putative macrophages.
• This stratification suggests a functional gradient, with APCs at the surface and innate immune functions deeper within the stroma.
• The findings challenge the traditional view of the cornea as immune-privileged and highlight its active immune surveillance role.