Abstract
Purpose :
Corneal neovascularization, induced by various ocular insults, compromises corneal transparency. The present study investigated the function of ocular surface mast cells in mediating corneal angiogenesis following ocular injury in a murine model of corneal angiogenesis.
Methods :
Distribution of mast cells at the ocular surface was evaluated by immunohistochemistry (IHC) analysis of avidin stained corneas of balb/c mice. Neovascularization was induced by placing a single figure-8 intrastromal suture on the nasal side of the cornea using 11-0 nylon suture. Mast cell activation was evaluated by quantifying mast cell specific β-tryptase and β-hexosaminidase levels in the tear wash. Vessel growth was clinically evaluated using slit lamp. Corneas were harvested and stained for CD31+ (vascular endothelial cell marker) for IHC analysis of microvascular angiogenesis. Mice were locally treated with mast cell blocker (2% cromolyn in PBS) to study the effect of mast cell inhibition on angiogenesis.
Results :
Immunohistochemistry analysis demonstrated abundance of mast cells in peripheral cornea and limbal area. Tear wash collected at 0, 3, 6 hours following intrastromal suture placement showed a significant 5-fold increase of tryptase (p<0.01) and a 2-fold increase in β-hexosaminidase levels, relative to naive controls. Significant neovascularization towards the site of suture placement was observed by day 4 post-surgery (3.6 ± 0.4% vs. 16.2 ± 1.6%; p<0.01). Treatment of cromolyn, a mast cell inhibitor, abated angiogenesis as observed under the slit lamp (12.4 ± 2.3% vs. 5.6 ± 0.03%; p<0.05). This effect was further confirmed with CD31+ IHC analysis demonstrating a significantly smaller vascular area compared to PBS-treated control (1.5 ±0.2 mm2 vs. 0.5 ± 0.02 mm2; p<0.01).
Conclusions :
Our data demonstrate that blockade of ocular surface mast cell activation inhibits neovascularization, suggesting mast cells contribute to corneal angiogenesis.
This is a 2020 ARVO Annual Meeting abstract.