Topical losartan inhibits corneal scarring fibrosis and collagen type IV deposition after Descemet's membrane-endothelial excision in rabbits

The purpose of this study was to examine the effect of topical and/or oral angiotensin converting enzyme II inhibitor and TGF-beta signaling blocker losartan on corneal stromal fibrosis that developed in rabbit corneas after Descemetorhexis removal of central Descemet's membrane and corneal endothelium. Twenty-eight New Zealand white rabbits were included and either had 8 mm central Descemetorhexis or sham control surgery without Descemetorhexis in one eye. Groups of 4 eyes without Descemetorhexis were treated for one month with no medications, topical losartan or oral losartan. Groups of 4 eyes with Descemetorhexis were treated with topical and oral vehicle, topical losartan, oral losartan, or both topical losartan and oral losartan for one month. Standardized slit lamp photos were obtained with central opacity intensity measured with ImageJ. The posterior fibrotic zone of corneas was measured on immunohistochemistry for alpha-smooth muscle actin (SMA) and keratocan using QuPath analysis. Collagen type IV expression in the posterior cornea was quantitated with ImageJ and duplex immunohistochemistry for collagen type IV and TGF beta-1. After Descemetorhexis, topical, but not oral, losartan decreased the intensity of central stromal opacity, reduced peripheral corneal scarring, and decreased alpha-smooth muscle actin myofibroblast fibrosis area compared to corneas that had Descemetorhexis and treatment with vehicles alone. Topical losartan decreased posterior stromal cellular, non-Descemet's membrane, collagen type IV production, that is likely stimulated by TGF beta as part of a negative regulatory feedback mechanism, compared to vehicle treatment at one month after Descemetorhexis. Topical losartan is likely to be effective in reducing corneal scarring fibrosis produced by traumatic injury, microbial infection, and some corneal diseases and surgeries.