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M. Takaoka, T. Nakamura, S. Kinoshita, Y. Ban; Cell Junction–Related Proteins in Gelatinous Drop–Like Corneal Dystrophy . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5550.
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© ARVO (1962-2015); The Authors (2016-present)
In Gelatinous Drop–like Corneal Dystrophy (GDLD), corneal epithelial permeability is reportedly higher than normal. Inferring that tight junction (TJ)–related proteins and basement membrane (BM)–related proteins in GDLD are incomplete, we investigated them both histopathologically and immunohistochemically.
A 65–year–old woman with a mutation at codon 118 (Q118X) underwent a lamellar keratoplasty. The corneal button was examined histopathologically by Congo red staining for the presence of amyloid, and immunohistochemically for the expression of TJ–related proteins (ZO–1, claudin–1, occludin), BM–related proteins (integlin α6ß4,/α3ß1, laminin–5, collagen IV/VII), and lactoferrin (the chief component protein of tears, as well as the ingredient of amyloid deposits in GDLD).
Massive subepithelial deposits in the central cornea were stained positively with Congo red. Epithelial cell layers adjacent to large deposits were abnormally thin, and each epithelial cell looked flattened by underlying deposits. Epithelial cells in the mid–periphery were seemingly normal, but an uncommon eosinophilic material between the epithelium and the Bowman’s layer formed a linear band. ZO–1 and occludin were interspersed on the surface of normal cornea, while they presented no immunofluorescence in GDLD. There was little difference in claudin–1 between cornea with GDLD and normal cornea. BM–related proteins adjacent to the massive deposits were often intermittent, while elsewhere formed a continuous line. This line, stretched by an underlying band–like area, formed spikes protruding into the Bowman’s layer. The band–like area was immunohistochemically shown to contain collagen IV/VII and laminin–5. Immunofluorescence of amyloid P and lactoferrin were positive in the Congo red–positive area, but negative in the band–like area.
This report proves that very few epithelial TJs exist in GDLD. Disruption of TJs possibly caused lactoferrin to permeate through the epithelium to the subepithelial amyloid deposit. Moreover, the BM arranged in a thorny pattern, deformed by the underlying subepithelial accumulation of collagenous material. This deformation was rarely reported previously, and has not been well defined. In sum, the lack of TJs and the disorganization of the BM may become a key to elucidate the pathogenesis of GDLD.
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