Matrix Metalloproteinase Inhibitor GM6001 (Ilomostat) Prevents TGF–ß Induced Subcapsular Cataract Formation in the Cultured Rat Lens.

Abstract

Abstract: : Purpose: Transforming growth factor ß (TGF–ß) has been shown to induce subcapsular cataracts in cultured rat lenses. We have shown previously that expression of the Matrix Metalloproteinase, MMP–2 (gelatinase A) is induced in rat lenses following treatment with TGF–ß and this expression was correlated with the location of subcapsular cataract plaques. In light of these data we investigated whether the MMP inhibitor, GM6001 (Ilomostat) could prevent the formation of subcapsular cataracts in the TGF–ß rat lens model. Methods: Lenses of senile Wistar male rats were removed and cultured in complete M199 media for a period of 6 days. The lenses were either left untreated (control) or treated with TGF–ß (1 ng/ml) or GM6001 (Ilomostat) (25µM) + TGF–ß. After the culture period, the lenses were observed and photographed, and fixed for histological evaluation and immunohistochemistry. An α–smooth muscle actin (αSMA) specific antibody was used to detect the presence of mesenchymal cells indicative of the lens epithelial to mesenchymal cell transition (EMT) that occurs prior to plaque formation. Results: After 6 days of culturing, control lenses (n=8) remained clear while lenses induced with TGF–ß (n=9) exhibited discrete subcapsular opacities across the anterior surface of the lens. Importantly, lenses cultured with TGF–ß and GM6001(n=9) resembled control lenses and were devoid of subcapsular opacities. Histologically, the TGF–ß treated lenses exhibited subcapsular plaques that showed strong immunoreactivity for αSMA whereas both the control lenses and the GM6001 + TGF–ß treated lenses did not. Conclusions: These data demonstrate the novel finding that GM6001, a well known inhibitor of MMP expression prevents TGF–ß induced subcapsular cataract formation in the excised rat lens. Furthermore the lack of αSMA expression in the GM6001+TGF–ß treated lenses suggests that MMPs may be involved in the EMT that occurs during subcapsular cataract formation. Further details regarding the inhibition in expression of specific MMPs by GM6001 in the TGF–ß rat lens model will be presented.

Keywords: cataract • growth factors/growth factor receptors • microscopy: light/fluorescence/immunohistochemistry