RESUMO
PURPOSE: A case of corneal lactoferrin amyloidosis secondary to trichiasis is reported. CASE: A 30-year-old male suffered from trichiasis with an elevated gray whitish lesion just under the center of the cornea in his right eye. The lesion had an irregular surface. METHOD: We excised the corneal lesion, and studied the excised corneal lesion morphologically. RESULT: The deposit observed just under the corneal epithelial layer was positive for Congo red staining, and showed dichroism under polarizing microscopy. The deposit also showed a immunoreactivity against anti-human lactoferrin antibody. CONCLUSION: The morphological study proved that the deposits under the corneal lesion were derived from lactoferrin. Long term injury of the corneal surface by trichiasis may lead to the deposition and structural changes of lactoferrin originating from tears.
Assuntos
Amiloidose/etiologia , Doenças da Córnea/etiologia , Pestanas , Lactoferrina/isolamento & purificação , Adulto , Amiloidose/metabolismo , Doenças da Córnea/metabolismo , Humanos , MasculinoRESUMO
We report a novel localized amyloidosis associated with lactoferrin. To elucidate the precursor protein of corneal amyloidosis associated with trichiasis, we analyzed amyloid deposits from three patients by histopathology and biochemistry. Amyloid deposits showed immunoreactivity, confirmed by electron microscopy, for only anti-human lactoferrin antibody. Electrophoresis of amyloid fibrils revealed lactoferrin with and without sugar chains; N-terminal sequence analysis revealed full-length lactoferrin and a truncated tripeptide of N-terminal amino acids, Gly-Arg-Arg. Carboxymethylated wild-type lactoferrin formed amyloid fibrils in vitro. Lactoferrin gene analysis in the three patients revealed a Glu561Asp mutation in all of the patients and a compound heterozygote of Ala11Thr and Glu561Asp mutations in one patient. A heterozygotic Glu561Asp mutation appeared in 44.8% of healthy Japanese volunteers, suggesting that the mutation may not be an essential mutation for amyloid formation (p = 0.104). Results thus suggest that lactoferrin is this precursor protein.
