Immunohistochemical characterization of Descemet's membrane in Fuchs' corneal dystrophy and PEX-keratopathy
T. Hammer, U. Schlötzer-Schrehardt, G. O. H. Naumann
Background: Both in Fuchs' endothelial dystrophy and pseudoexfoliation (PEX) keratopathy, an abnormal extracellular material is produced and deposited onto Descemet's membrane (DM). In order to facilitate the histopathological differential diagnosis the aim of this study was to detect potential differences in the composition of this abnormal material in both entities with the use of lightmicroscopic immunohistochemistry.
Material and methods. Five corneas from each group (Fuchs' dystrophy, PEX keratopathy and normal corneas) were investigated by immunofluorescence microscopy using a panel of 29 antibodies against extracellular matrix components, such as collagens, proteoglycans and elastic fiber components.
Results: Both in Fuchs' dystrophy and in PEX keratopathy, abnormal basement membrane material and a loose fibrillar layer was found deposited on the normal DM. In contrast to normal controls, a positive immunoreaction for the elastic microfibril components LTBP-1 and ßig-h3 could be detected in the predescemetal stroma and for LTBP-1 , fibrillin-1 and -2, MAGP-1 as weIl as heparan-sulfat-proteo glycan in the posterior fibrillar layer in both Fuchs' and PEX endotheliopathies. Apart from a slight increase in fibrillin-1 immunolabeling in PEX keratopathy, no qualitative differences in the composition of these abnormal deposits on DM could be established between Fuchs' dystrophy and PEX keratopathy.
Conclusions: In Fuchs' dystrophy and PEX keratopathy the diseased corneal endothelium produces an abnormal extracellular material, which can be characterized by immunohistochemical markers, especially against elastic microfibril components. A clear-cut histopathological differential diagnosis is, however, not possible by immunohistochemistry.
Department of Ophthalmology, University of Erlangen-Nürnberg, D-91054 Erlangen