Differential regulation of key stages in early corneal wound healing by TGF-β Isoforms and their inhibitors

PURPOSE. Inhibition of TGF-beta reduces myofibroblast differentiation and fibrosis in the cornea. Determining the actions of distinct TGF-beta isoforms and their inhibitors during early corneal wound healing is an essential step in guiding therapeutic intervention. METHODS. Bovine serum-free corneal cell and wounded organ cultures were challenged with a range of concentrations of TGF-beta(1), -beta(2), and -beta(3); IL-10; and neutralizing human monoclonal antibodies (mAbs) against TGF-beta(1) (CAT- 192) or -beta(2), (CAT- 152). Cultures were assessed for re-epithelialization, proliferation ( cell counts and cresyl violet assay), morphology ( histologic examination), repopulation of the area under the wound, and myofibroblast transformation (alpha-smooth muscle actin) between 0 and 5 days. RESULTS. TGF-beta(1) delayed re-epithelialization, increased repopulation of the stroma, increased keratocyte proliferation and was the only isoform to promote myofibroblast differentiation. The anti-TGF-beta(1) mAb, CAT-192 promoted re-epithelialization and reduced repopulation of the stroma. Exogenous TGF-(beta)3 had little effect on re-epithelialization but reduced repopulation of the stroma. IL-10 promoted corneal re-epithelialization at low doses but inhibited this response at high doses. Stromal repopulation was prevented by all doses of IL-10. TGF-beta(2) or the anti-TGF-beta(2) mAb, CAT-152 had little effect on any repair parameter. CONCLUSIONS. The results confirm TGF-beta(1) as the principal isoform in corneal wound healing and suggest that inhibition of the action of TGF-beta(1) can promote corneal wound healing. Treatment with the anti-TGF-beta(1) mAb CAT-192 accelerates corneal re-epithelialization but reduces cell repopulation of the stroma. The cytokines TGF-beta(3) and IL-10 have opposing actions to that of TGF-beta(1).