Localization of tissue inhibitor of metalloproteinases-3 in neurodegenerative retinal disease.

Tissue inhibitor of metalloproteinases-3 (TIMP-3) is one of a family of genes whose products are implicated in the regulation of remodelling of the extracellular matrix. The level of mRNA coding for TIMP-3 is increased in retinas affected by the photoreceptor degenerative disease, simplex retinitis pigmentosa (RP), and mutations in TIMP-3 are associated with an inherited form of macular dystrophy. Here we compare TIMP-3 protein expression in normal retina and in those affected by RP and by age-related macular degeneration. Immunoreactive TIMP-3 is present in normal retinal pigment epithelium, and in degenerative retinas particularly at Bruch's membrane and additionally in photoreceptor-retaining regions in simplex RP. The pattern suggests a role for TIMP-3 in normal retinal homeostasis, and, in the disease state, in the modulation of extracellular matrix metabolism and neovascularization.