Abstract
Purpose: :
The presence of resident corneal antigen presenting cells (APC) has now firmly been established and APC density is currently being used by investigators as a marker for inflammation in corneal disease. Currently, random areas are chosen for quantification of APC. However, the peripheral distribution of APC in the cornea remains unknown. In this study we evaluate the peripheral and central distribution of APC populations in normal and inflamed corneas.
Methods: :
Six to 8-week old C57BL/6 mice were investigated. Normal corneas and inflamed corneas, one week after cautery, were marked and excised. Immunofluorescence histochemistry was performed for a combination of markers, including major histocompatibility complex (MHC)-II, CD45, CD11b, CD11c, and F4/80 (n=3/staining/group). Isotype controls were used as controls. Samples underwent confocal microscopy for all peripheral quadrants (superior, inferior, nasal, temporal) and the central cornea. Three images per area (20x) were quantified for all markers for cell density using Image J software. ANOVA was used to assess significance.
Results: :
The normal cornea demonstrated significant variation in APC density, with higher density of cells in superior/inferior quadrants, as compared to nasal/temporal quadrants with differences of up to 88.9%. CD45+ bone marrow (BM)-derived cells and CD11c+ dendritic cells (DC) showed 22.3% (p=0.05) and 29.5% (p>0.05) variability between quadrants respectively, there was a much larger variability for mature MHC-II+ (48.9%) cells, as well as for monocytic CD11b+ cells and F4/80+ macrophages (up to 88.9%; p=0.01) between superior/inferior and nasal/temporal quadrants. After inflammation, the density of for all markers increased compared to controls. While CD45+ BM cells demonstrated is 30.2% variation between vertical as compared to horizontal quadrants, the variability in MHC-II+ (207.9%) and CD11c+ DC (35.5%) density increased (p=0.02). In contrast density of F4/80+ CD11b+ was less more uniform with only 20.5% variability (p>0.05).
Conclusions: :
Different peripheral distribution of APC populations was found in normal corneas for the four anatomic peripheral quadrants. After inflammation, the increase in APC for the peripheral quadrants is asymmetric. Our data shed new light in the immunobiology of corneal APC.
Keywords: cornea: basic science