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A. J. Huang, D. A. Patel, G. J. Harocopos, S. H. Chang, D. H. Thang; Sub-Epithelial TGFBI Deposits in Avellino Corneal Dystrophy. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4312.
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© ARVO (1962-2015); The Authors (2016-present)
Avellino corneal dystrophy (ACD) is known to have both lattice and granular stromal deposits, presumably caused by aggregation of mutant transforming growth factor ß-induced protein (TGFBI). This study further investigates the use of Thioflavin-T (ThT), a fluorescent stain for amyloid protein, in characterizing the corneal deposits of ACD.
Histopathological sections of corneas obtained from three unrelated patients with a clinical diagnosis of ACD after corneal transplantation were studied. Sections from normal adults and three unrelated lattice corneal dystrophy (LCD) patients were used as controls. Sections were stained with routine histochemical stains including alcian blue, Congo red, and Masson trichrome. Sections were also stained immunofluorescently with an anti-TGFBI antibody and 200 µM ThT, and imaged with laser confocal microscopy.
Consistent with clinical diagnoses, lattice stromal deposits stained with Congo red showing birefringence and dichroism under polarized light, and granular stromal deposits stained with Masson trichrome in all three ACD cases. These stromal deposits stained with TGFBI antibody and ThT. In addition to lattice and granular deposits, previously uncharacterized sub-epithelial deposits identified with TGFBI antibody were observed in ACD cases and a control case of recurrent LCD. Interestingly, the anterior component of these TGFBI sub-epithelial deposits stained negatively with ThT. In the control LCD sections, stromal deposits stained positively with ThT but not with Masson trichrome, confirming lack of granular deposits.
As an adjunct to TGFBI antibody in immunofluorescence, ThT can be as effective as Congo red in identifying amyloid aggregates in LCD and ACD. Our results confirm that lattice and granular stromal deposits consist of TGFBI. Previously unreported non-amyloidogenic TGFBI deposits may also manifest in the anterior sub-epithelial zone along with classic stromal deposits.
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