TSG-6 Protects Corneal Endothelium From Transcorneal Cryoinjury in Rabbits

Abstract

PURPOSE. To investigate the effect of an anti-inflammatory protein, TNF-alpha stimulated gene/protein (TSG)-6 and an antiapoptotic protein, stanniocalcin (STC)-1 on corneal endothelium in rabbits with transcorneal cryoinjury. METHODS. Transcorneal freezing (-80 degrees C) was applied to rabbit corneas for 30 seconds. Immediately post injury, either TSG-6 (10 mu g/100 mu L), STC-1 (10 mu g/100 mu L), or the same volume of balanced salt solution (BSS) was injected into the anterior chamber. Each eye was examined for corneal opacity, corneal thickness, endothelial cell density, and endothelial hexagonality every 2 to 6 hours for 48 hours post injury. The concentrations of myeloperoxidase (MPO) and IL-1 beta were measured in the aqueous humor every 6 hours. At 48 hours post injury, each cornea was assayed for TNF-alpha, IL-1 beta, IL-6, and MPO, and histologically evaluated with alizarin red-trypan blue staining, hematoxylin-eosin staining, and immunostaining for neutrophils. RESULTS. Tumor necrosis factor-alpha stimulated gene/protein-6 significantly decreased the development of corneal opacity and edema after cryoinjury compared with STC-1 or BSS. The corneal endothelial cell density and hexagonality were markedly preserved by TSG-6. The mRNA levels of TNF-alpha, IL-1 beta, and IL-6 in the cornea and the protein levels of MPO and IL-1 beta in the aqueous humor and cornea were significantly lower in TSG-6-treated eyes than BSS-treated controls. Similarly, the expression of fibroblast growth factor-2 was reduced by TSG-6 treatment. Histologic evaluation demonstrated that neutrophil infiltration of the cornea was decreased in TSG-6-treated eyes. CONCLUSIONS. Tumor necrosis factor-alpha stimulated gene/protein-6 protected corneal endothelial cells from transcorneal cryoinjury through suppression of inflammation