Abstract
Purpose :
To investigate the effects of local and systemic inflammation on the number and size of corneal epithelial dendritic cells (DCs) in mice.
Methods :
Anaesthetised C57BL/6J wild-type mice received a central 1mm corneal epithelial injury (Alger Brush) and topical application of either sterile saline or the TLR9 agonist CpG-ODN. Corneas were examined four weeks later. Corneas from naïve mice and contralateral untreated eyes were used as controls. In another study, CD11c-eYFP mice received an intraperitoneal injection of lipopolysaccharide (LPS; 9mg/kg) or sterile saline and corneas were dissected two or 24 hours later. Corneal flatmounts were immunostained using MHC Class II and CD45 antibodies and images of the central and peripheral cornea were acquired using confocal microscopy. The density and size (dendritic tree area) of epithelial DCs were quantified by a masked observer using ImageJ.
Results :
Compared to intact corneas, there was a 1.5-2 fold increase in DC density in both the central and peripheral cornea (P = 0.007) 4 weeks following both sterile injury (central; P = 0.04, peripheral P = 0.008) and CpG-induced inflammation (central; P = 0.02, peripheral P = 0.02). In intact corneas, the size of DCs was lower in the central versus the peripheral corneal epithelium (mean ± SEM; 1415 ± 117 μm2 vs 1817 ± 103 μm2, P = 0.004). After both injury and CpG, DC size increased in the central cornea (injury; P < 0.001, CpG; P = P < 0.001). In the cornea contralateral to the treated eye, there was a significant increase in the size of DCs in the central cornea compared to corneas from naïve mice (P = 0.005). Following systemic LPS, the density of CD11c-eYFP+ cells was unchanged in both corneal regions at both time points, however there was a 35% reduction in the size of DCs in the central cornea after two hours (P = 0.02), returning to baseline after 24 hours. DC size was also reduced in the peripheral corneal epithelium, however this effect was observed at both two hours (P < 0.001) and 24 hours (P < 0.001) post-injection.
Conclusions :
These data provide insights into the effects of local and systemic inflammation on the morphology of corneal epithelial DCs in mice. Effects are apparent as early as two hours post systemic inflammation and are sustained up to four weeks after local challenge. Further phenotypic analyses are underway to correlate these observed morphological changes with functional capacity.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.