Abstract
Purpose: :
To analyze the involvement of the corneal endothelium in uveitis in order to better understand the formation mechanisms and the keratic precipitate composition. In vivo confocal microscopy images were correlated with ex vivo immunostaining of corneal endothelium from rat eyes with endotoxin-induced uveitis (EIU).
Methods: :
EIU was induced in Lewis rats by lipopolysaccharide (LPS) injection. Slit-lamp examination and in vivo confocal microscopy were performed 6, 24, 48, 72 and 96 h after the LPS injection; one group of rats was killed at 24 h and the other rats at 96 h. Immunohistochemistry on corneal endothelium, using antibodies to intercellular adhesion molecule (ICAM-1), phalloidin, CD68 (anti-macrophage), MA967 (anti-granulocyte), alpha beta-TCR (anti-lymphocyte), Zonula Occludens-1 and occludin was performed on flat-mount corneas and was analyzed using a 3D laser confocal microscope.
Results: :
In vivo confocal microscopy showed numerous hyper-reflective round dots on the corneal endothelium, in the anterior chamber and in the anterior stroma corresponding to inflammatory cells until 96 h, peaking at 24 h. On immunostaining, endothelial cells in rats with EIU overexpressed ICAM-1. ZO-1 and occludin had a lower endothelial expression and more heterogeneous distribution in EIU rats than in controls, showing disruption of endothelial cell junctions. Compared to controls, CD68, MA 967 and alpha beta-TCR expression was observed in corneas in rats with EIU. The two techniques showed a circular peripheral network of corneal vessels, derived from a large circumferential vascular structure resembling the major arterial circle of iris, from where the inflammatory cells marginated to infiltrate the anterior stroma.
Conclusions: :
The correlation between in vivo confocal microscopy and ex vivo immunostaining helped to better understand in vivo confocal microscopy images. The two new techniques applied here were very effective and complementary in evaluating the corneal endothelium involvement in EIU. Based on these findings, in vivo confocal microscopy in clinical practice could be very helpful to better analyze keratic precipitates and corneal modifications in patients with uveitis.
Keywords: cornea: endothelium • microscopy: confocal/tunneling • inflammation