Normal expression levels of cathepsins, protease inhibitors, and Sp1 in conjunctival tissues from patients with keratoconus

Purpose. In keratoconus corneas, it has been shown that levels of degradative enzymes and transcription factor Sp1 are elevated and those of inhibitors are reduced, especially in the epithelial layer. This study is to determine whether the biochemical abnormalities identified in corneas also exist in conjunctival tissues. Methods. Conjunctival tissues were collected from normal subjects and from patients with keratoconus, senile cataract, and other corneal diseases. Immunohistochemical staining for cathepsins B and G, alpha1-proteinase inhibitor, alpha2-macroglobulin and Sp1 was performed. Results. The epithelium of all conjunctival specimens showed immunoreactivity toward the antibodies. The staining for cathepsins B and G, and the inhibitors was mostly cytoplasmic, while that for Sp1 was nuclear. The staining intensity in keratoconus specimens was all within normal range. Conclusions. These results suggest that the abnormalities in cathepsins B and G, protease inhibitors and Sp1 identified in keratoconus corneas are not manifested in the conjunctiva. Keratoconus appears to be a disease localized to the cornea.