Corneal synthesis of alpha 1-proteinase inhibitor (alpha 1-antitrypsin)

Abstract

Purpose: To determine if the cornea synthesizes alpha 1-proteinase inhibitor (alpha 1-antitrypsin).

Methods: Human corneas were placed in organ culture for 24 hours in the presence of 35S-methionine to radiolabel corneal proteins. Monoclonal antibodies were used to precipitate labeled alpha 1-proteinase inhibitor. The immunologically isolated inhibitor was electrophoresed on polyacrylamide gels and visualized by autoradiography or by staining for protein. Human corneas were also fixed with formalin and imbedded in paraffin. Sections were probed with 3H-labeled complementary DNA probes to the coding region of alpha 1-proteinase inhibitor.

Results: Metabolically labeled alpha 1-proteinase inhibitor was recovered from organ-cultured corneas and the cornea-conditioned medium. Specific messenger RNA was observed in the cornea by in situ hybridization most prominently in corneal epithelial cells.

Conclusions: alpha 1-Proteinase inhibitor is synthesized and released by human corneal epithelial cells. These results indicate that the cornea has the ability to locally control degradation through synthesis of this inhibitor without total dependence on a supply of the inhibitor from the vascular system.