Smad3 plays a central role in the TGF?-mediated fibrosis with characteristic inflammation, proliferation and transformation of fibroblasts and epithelial-to- mesenchymal transition. Gene therapy and small chemicals targeting Smad3 signaling have shown great potentials for the successful fibrosis management. One potent synthetic compound that effectively inhibits the phosphorylation of Smad3 has already been approved by FDA to treat scleroderma and skin fibrosis disorders. In addition, with their anti-angiogenesis effects mediated via Smad3 inhibition, Smad3 inhibitors have also been tested in clinical trial as a neovascularization-suppressing agent for treating solid tumors such as melanoma. Since ocular tissues are vulnerable to fibrosis and neovascularization which can compromise the visual acuity, Smad3 inhibitors present new opportunities for treating above mentioned disorders in the eye. In this proposal, we plan to test two commercially available Smad3 inhibitors for their inhibitory effects on fibrosis and neovascularization. Furthermore, our preliminary study revealed that Smad3 is the key regulator for the expression of keratoepithelin. Keratoepithelin aggregates and leads to the abnormal amyloid fibril/amorphous deposits in certain types of stromal corneal dystrophies. Smad3 inhibitors may serve as suppressors for keratoepithelin expression and delay or prevent the recurrence of the abnormal deposits in corneal dystrophy patients. We will first investigate the expression of collagens, matrix metalloproteinases and keratoepithelin under Smad3 inhibitor treatment on corneal explant cultures. The fibrosis and neovascularization by alkaline burn, mechanical debridement and trabeculectomy surgery will be conducted on rabbit cornea and conjunctiva for the evaluation of Smad3 inhibitors. In addition, the anti-fibrosis potency of Smad3 inhibitors on lens and extraocular muscle injuries mimicking cataract and strabismus surgeries will be investigated in rabbits as well. The insights gained from this study are clinically significant and will greatly facilitate developing an effective treatment for fibrosis and neovascularization in ocular tissues.
The goal of this research is to test the Smad3 inhibitors for potential ophthalmic applications to treat fibrosis, neovascularizaiton and KE-related corneal dystrophies. Expression of fibrosis- and angiogenesis-related genes will be analyzed biochemically and by immunostainings in corneal explant cultures and animal models. Our results will provide insights for developing new treatments for these ocular conditions.
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