Fuchs endothelial corneal dystrophy: aspects of pathogenesis

Fuchs endothelial corneal dystrophy (FECD) – multigenic bilateral disorder, characterized by dysfunction of corneal endothelium cells (CECs) that eventually results in loss of transparency. Purpose: To evaluate the pathogenesis of FECD with histological and immunohistochemical methods, immunofluorescence, scanning electron microscopy (SEM). Methods: Endothelium–Descemet membrane (EDM) complexes, corneal buttons were obtained from 76 patients (85 eyes) with FECD during keratoplasty and divided into 1A, 2A, 3A groups, 15 EDMs (donor tisuue) – 1B, 2B, 3B groups (control). Morphological (hematoxylin/eosin staining) and immunohistochemical (primary antibodies to cytokeratin AE1/AE3 and vimentin) studies (1A, 1B groups), phase-contrast microscopy and immunofluorescence analysis of tight junction protein ZO-1 (2A, 2B groups), SEM (3A, 3B groups) were performed. Results: FECD is characterized by decline of CECs, cell and nuclear enlargement. Nuclear-cytoplasmic ratio of CECs is relative to control. CECs expression ZO-1 is decreased in the area of guttae ingrowth. Coexpression of cytokeratin AE1/AE3 and vimentin is found. Morphological and immunohistochemical studies show DM’ thickening, stromal and epithelial edema and local fibrosis, vimentin (stromal cells) and cytokeratin AE1/AE3 (epithelium) expression in FECD. Conclusion: Pathogenesis of FECD include CECs’ epithelial-mesenchymal transition, followed by guttae formation – the excrescences, which destroy cytosketon and lead to progressive loss of CECs. Changes in permeability of endothelium cause edema and fibrosis of stroma and epithelial layer.