Immunohistochemical localization of urokinase-type plasminogen activator, urokinase-type plasminogen activator receptor and α2-antiplasmin in human corneal perforation: a case report

Background: Corneal ulceration leading to perforation is associated with infectious and non-infectious destructive conditions in the cornea. The fibrinolytic (plasminogen/plasmin) system is considered to contribute to tissue remodeling in the wound healing process and it is believed to play an important role in proteolysis and fibrosis. To determine the localization of urokinase-type plasminogen activator (u-PA), u-PA receptor (u-PAR) and alpha 2-antiplasmin (alpha 2AP) in the tissue of a corneal perforation, we investigated immunohistochemical expressions of u-PA, u-PAR, alpha 2AP, CD68, and alpha-smooth muscle actin (alpha-SMA) in a patient with corneal perforation that developed from an ulcer of no clear cause. Case presentation: The patient was a 77-year-old woman who presented with a perforated corneal ulcer in her right eye. The cause of her corneal ulcer was unknown. Double immunohistochemistry was performed for the combinations of u-PA with u-PAR, CD68 or alpha-SMA and alpha 2AP with CD68 or alpha-SMA to detect the localization of u-PA and alpha 2AP. u-PA and u-PAR co-localization was seen in the corneal ulceration area. u-PA was mainly observed in CD68-positive cells and in some alpha-SMA positive cells. On the other hand, alpha 2AP was not expressed in CD68-positive cells, but was expressed in alpha-SMA positive cells. Conclusion: We identified expression of the u-PA/u-PAR complex and alpha 2AP in a patient with a corneal ulcer. These two molecules are believed to play a crucial role in inflammatory cell recruitment, ECM synthesis and degradation during corneal wound healing.