TIMP-3, collagen, and elastin immunohistochemistry and histopathology of Sorsby's fundus dystrophy.
OBJECTIVE
Mutations in the tissue inhibitor of metalloproteinases-3 (TIMP-3) gene have previously been identified in patients with Sorsby's fundus dystrophy (SFD). We evaluated the ocular distribution of TIMP-3 and other extracellular constituents in SFD.


METHODS
The eyes of an SFD donor with a confirmed TIMP-3 mutation were examined using histologic techniques demonstrating connective tissue, calcium, and lipid. Immunohistochemical analyses were performed using antibodies against TIMP-3, collagen type IV, V, and VI, laminin, fibronectin, elastin, and fibrillin. Electron microscopy also was used.


RESULTS
A subretinal pigment epithelium (sub-RPE) deposit similar to that previously described was seen. A morphologically similar but different deposit was present internal to the nonpigmented ciliary epithelium (NPCE). Both deposits contained collagens, elastin, glycosaminoglycans, lipids, and calcium. Immunolabeling of TIMP-3 was found in the basement membrane of the NPCE, Bruch's membrane, and choroidal vessels in normal control subjects. In SFD, immunolabeling of TIMP-3 also was present in the sub-RPE deposit and in the inner portion of the ciliary body deposit. TIMP-3 immunoreactivity was more extensive in the SFD eye. The pattern of elastin immunoreactivity was remarkably similar to that of TIMP-3. Electron microscopy revealed a morphologically altered elastic layer of the Bruch's membrane.


CONCLUSIONS
Sub-RPE TIMP-3 immunoreactivity appears more extensive in SFD than in control subjects. There is also a correspondence between TIMP-3 and elastin immunoreactivies, which invites speculation as to a link between the SFD TIMP-3 mutation and altered elastin processing. The accumulation of abnormal material in SFD is more widespread than previously reported. In view of this, SFD might be better termed Sorsby's ocular epitheliopathy.
Chong
N H
NH
Department of Pathology, Institute of Ophthalmology, University College London, England.
Alexander
R A
RA
Gin
T
T
Bird
A C
AC
Luthert
P J
PJ
D000368:Aged; D001485:Basement Membrane / Q000378:metabolism; D002924:Ciliary Body / Q000378:metabolism / Q000648:ultrastructure; D003094:Collagen / Q000378:metabolism*; D004549:Elastin / Q000378:metabolism*; D005260:Female; D005654:Fundus Oculi; D006801:Humans; D007124:Immunoenzyme Techniques; D008268:Macular Degeneration / Q000378:metabolism* / Q000473:pathology; D009154:Mutation; D010857:Pigment Epithelium of Eye / Q000378:metabolism / Q000648:ultrastructure; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000235:genetics / Q000378:metabolism*
D019717:Tissue Inhibitor of Metalloproteinase-3; D003094:Collagen; D004549:Elastin