epsilon-(gamma-glutamyl)-lysine and Corneal-Injuries

To investigate transglutaminases (enzymes capable of cross-linking extracellular matrix proteins to proteolysis-resistant complexes during scar tissue formation) in a human donor cornea after successful laser in situ keratomileusis (LASIK) without clinical complications and to compare with the results in a human donor cornea with corneal scarring after corneal injury.. Department of Ophthalmology, Ludwig-Maximilians University, Munich, Germany.. A donor cornea with prior uneventful LASIK treatment and 1 with corneal scarring after penetrating injury were investigated. Cryostat sections were stained immunohistochemically for tissue transglutaminase (tTG), keratocyte transglutaminase (kTG), and their reaction product epsilon-(gamma-glutamyl)-lysine.. With light microscopy, the flap interface of the LASIK-treated eye could hardly be detected, while in the injured eye, infiltration of cells and a clear margin next to the scar formation were present. Immunohistochemistry demonstrated a distinct staining for tTG, kTG, and epsilon-(gamma-glutamyl)-lysine in the corneal scar. In contrast, neither transglutaminase nor epsilon-(gamma-glutamyl)-lysine staining could be observed at the flap margin or in the interface of the LASIK-treated donor eye.. Irreversible protein cross-linking of transglutaminases via epsilon-(gamma-glutamyl)-lysine connections seem to be indicators for scarring in corneal wound healing. The absence of transglutaminases and their reaction product epsilon-(gamma-glutamyl)-lysine in a LASIK-treated cornea supports the idea of missing scar tissue formation after LASIK surgery.

Topics: Adult; Cicatrix; Cornea; Corneal Injuries; Dipeptides; Extracellular Matrix Proteins; Eye Injuries, Penetrating; Fluorescent Antibody Technique, Indirect; GTP-Binding Proteins; Humans; Keratomileusis, Laser In Situ; Keratoplasty, Penetrating; Male; Middle Aged; Myopia; Protein Glutamine gamma Glutamyltransferase 2; Tissue Donors; Transglutaminases; Wound Healing