Abstract
Purpose: :
It has been reported that neutrophils greatly contribute to corneal inflammation resulting from an alkali injury. In lysin-motif green fluorescent protein (LysM-GFP) mice, myelomonocytic cells are labeled with GFP in vivo, and the resulting endogenous neutrophils are brightly labeled and monocytes and macrophages are also labeled, but to a lesser extent. The purpose of this present study was to analyze neutrophil dynamics in alkali-injury-associated corneal inflammation using LysM-GFP mice.
Methods: :
A 2-mm-diameter corneal alkali injury was created on the corneas of LysM-GFP mice with 1N-NaOH, an extremely corrosive sodium hydroxide solution. The corneal tissues were collected at 0, 3, 6, 12, 24, 48, 72, and 120 hours after alkali injury, and then analyzed by confocal microscopy.
Results: :
In the normal corneas (0 hours) of the LysM-GFP mice, LysM strongly-positive cells (neutrophils) were found to be in the corneal stroma of only the limbus. At 3 hours after alkali injury, there was no obvious change. At 6 hours after injury, the neutrophils moved toward the boundary of the alkali injury site. At 12 hours after injury, the neutrophils were gathered to the boundary, however, they were yet to be observed at the site of injury. At 24 hours after injury, neutrophils infiltrated to the injury site, and at 48 hours after injury, the neutrophils had reached the central part of the cornea. At 72 hours after injury, the neutrophils remained and infiltrated densely into the injury site, although the corneal epithelial defect had disappeared by that time. At 120 hours after injury, although the corneal opacities had nearly disappeared, the neutrophils were present at the injury site and the limbus.
Conclusions: :
The results of this study show that neutrophils are present in the stroma of only the limbus under normal conditions, however, those cells move to the entire stroma of the cornea after alkali injury.
Keywords: cornea: stroma and keratocytes • inflammation • wound healing