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J. D. Zieske, A. E. K. Hutcheon, P. H. Weinreb, S. M. Violette, M. A. Stepp; Expression of Local Activators of TGF-ß During Corneal Wound Repair. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1956.
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TGF-ß is a potent regulator of wound repair. As such, TGF-ß is normally secreted in a latent form that must be activated to express its action. The goal of the current investigation was to examine the expression of two known activators of TGF-ß, the integrin αVß6 and thrombospondin-1 (TSP-1), during corneal wound repair.
Adult Sprague-Dawley rats and adult 129Sv mice were used in all experiments. Two wound models were examined. In the first model, 3mm (rats) or 1.5mm (mice) debridement wounds were made in the central cornea. In the second model, 3mm (rats) or 1.5mm (mice) superficial keratectomy wounds were created in the central cornea. Wounds were allowed to heal from 4 hours to 7 days. Indirect immunofluorescence microscopy was used to localize αVß6 and TSP-1. Unwounded rat and mice corneas served as controls.
In unwounded corneas, αVß6 was present at low levels in the epithelial basal cell layer. TSP-1 was primarily in Descemet’s membrane and the corneal endothelium. In the rat corneas, αVß6 was rapidly upregulated in the epithelium migrating to cover the wound in both wound models. In the debridement model, expression of αVß6 returned to control levels by 2 days after wounding. Elevated levels persisted in the keratectomy model for up to 7 days. TSP-1 levels also increased following both types of wounds. Localization was primarily seen in the fibroblasts and matrix subjacent to the wound. Maximal expression was observed 8-16 hours after wounding. Expression of TSP-1 appeared to be at higher levels in the keratectomy model than in the debridement model. Similar results were observed in the mice; however, the upregulation of αVß6 was less apparent after a debridement wound than seen in rats.
The temporal and spatial expression of αVß6 and TSP-1 is consistent with these proteins being involved in the activation of TGF-ß during corneal wound repair.
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