Presence of proteinase inhibitor‐9 and granzyme B in healthy and pathological human corneas

Abstract

SummaryAim: To determine whether proteinase inhibitor‐9 (PI‐9) and granzyme B (GrB) are expressed in normal and pathological corneas.Methods: Cryosections and endothelial, epithelial and conjunctival imprints of 12 human cadaverous corneo‐scleral discs and 13 pathological corneas (corneal melting and herpes virus keratitis) were used. Protein localization was examined using fluorescent and enzymatic immunohistochemistry, and mRNA expression was determined by qRT‐PCR.Results: PI‐9 is predominantly expressed in the superficial and suprabasal epithelial layers of the cornea and conjunctiva. The corneal endothelium showed positivity in about 50% of cells. GrB was weakly present in healthy corneal epithelium and endothelium. The expression of both proteins was confirmed using qRT‐PCR. Besides altered expression in pathological corneas, strong positivity for PI‐9 and GrB was present in stromal infiltrates and some stromal cells that were positive for HLA‐DR and CD45. A marker typical of keratocytes, CD34, was decreased or totally absent in pathological infiltrates.Conclusions: The changes of PI‐9 and GrB expression in pathological tissue indicate that these proteins participate in the corneal immune response during the inflammatory process.