Abstract
Abstract: :
Purpose: Current literature has shown that TGF–ß1 plays a pivotal role in formation of anterior subcapsular cataracts (ASC). We therefore made use of our previously validated adenoviral gene transfer method to over–express active TGF–ß1 in the mouse eye in an attempt to induce ASC and the epithelial–to–mesenchymal transition (EMT) of the lens epithelium associated with these cataracts. Methods: Recombination–deficient adenovirus containing the transgene encoding active porcine TGF–ß1 (or empty vector, AdDL; or LacZ, AdLacZ) was injected into the anterior chamber of 6–8 week old C57 black mice. Four days post injection, animals were enucleated and eyes were processed for routine histology or LacZ staining. In addition, we used immunohistochemical techniques to localize alpha smooth muscle actin (αSMA) for detecting cells with a myofibroblastic phenotype, demonstrative of EMT. Results: After 4 days post injection with AdLacZ (5x10^8), intense blue staining can be seen in all structures of the aqueous outflow pathway and the corneal endothelium, but not in the lens epithelium, indicating that these cells were not infected with the adenovector. In contrast, higher doses of AdLacZ (1x10^9) resulted in a faint, yet identifiable stain in the lens epithelium. Adenovirally delivered active TGF–ß1, at a high dose, resulted in the formation of distinct subcapsular plaques that were immunoreactive to α–SMA expression. Additionally, increased α–SMA staining was observed in cells lining the anterior angle. Eyes that received control vector, AdDL, did not exhibit any of the changes observed in the AdTGF–ß1 treated eyes. Conclusions: Our study has shown that modified, replication–deficient adenoviruses can be efficiently delivered into structures of the anterior chamber, as well as, the lens epithelium, the latter of which has been controversial. Moreover, this is the first in vivo demonstration that adenovirally administered active TGF–ß1 transgene can induce ASC. Since this mode of delivery can induce ASC within four days post injection, it will be a powerful model for examining the effects of TGF–ß1–induced cataractogenesis in genetically modified animals including those involved in the Smad signaling pathway and matrix turnover.
Keywords: cataract • adenovirus • cytokines/chemokines