Abstract
Purpose: :
Acanthamoeba keratitis shows histological keratocyte depletion in human corneal stroma. We investigated how Acanthamoebas from corneas with Acanthamoeba keratitis affect human corneal stromal cells in vitro.
Methods: :
Acanthamoebas were isolated from patients with Acanthamoeba keratitis and their genotype was identified. Cytopathic effects of Acanthamoeba on cultured corneal fibroblasts from donor corneas were evaluated on the dishes in various conditions. Annexin-V and propidium iodide staining classified apoptotic cells, necrotic cells and viable cells. DNA laddering detected existence of apoptotic cells. Phagocytosis of corneal fibroblasts by Acanthamoeba was observed on culture dishes under confocal microscope.
Results: :
All Acanthamoebas from corneas of Acanthamoeba keratitis were T4 genotype. Acanthamoeba have cytopathic effects on human corneal fibroblasts by direct adhesion, but not chemical mediators. Cytopathic effects were detected in all Acanthamoebas from patients of keratitis. Acanthamoeba mainly killed corneal fibroblasts by apoptosis. Confocal microscope showed fragments of corneal fibroblasts phagocytosed by Acanthamoeba.
Conclusions: :
Acanthamoebas from Acanthamoeba keratitis have cytopathic effects on human corneal fibroblasts mainly due to apoptosis by direct adhesion. Our findings may provide a clue to explain the pathophysiology of corneal keratocyte depletion for human corneas with Acanthamoeba keratitis.
Keywords: Acanthamoeba • cornea: stroma and keratocytes • apoptosis/cell death