Abstract
Purpose: :
Purpose: Sorsby fundus Dystrophy (SFD) is a dominantly inherited, early onset macular degenerative disorder with development of choroidal neovascularization (CNV) similar to age-related macular degeneration. We have previously demonstrated that SFD-related S156C TIMP3 mutation expressed in human retinal pigment epithelial (RPE) cells reduces matrix metalloproteinase (MMP) inhibition and may promote angiogenesis. The objective of this study was to determine the mechanisms underlying SFD mutant TIMP3-induced angiogenesis.
Methods: :
Methods: Human RPE cells expressing wild-type and SFD S156CTIMP3 were analyzed for MMP inhibitory activity and gelatinase activity by reverse zymography and zymography. MMP2, MMP9 and VEGF proteins in the conditioned medium (CM) were quantitated by ELISA. In vitro angiogenesis assays were used to examine the migration, proliferation and tube formation of endothelial cells by the CM, VEGF and active MMP2, in the presence or absence of VEGF antagonists and MMP2 and MMP9 inhibitor (SB-3CT).
Results: :
Results: S156C mutant TIMP3 reduced MMP inhibitory activity and increased MMP activity in RPE cells. Total MMP2 (pro- and active forms) but not MMP9 level in the CM of the mutant cells was 3-5 fold higher than those of the control cells. VEGF protein level was decreased by ~45% in the cells expressing WT-TIMP3 cells but unchanged in the mutant cells relative to the control cells. The CM from mutant cells induced endothelial cell tube formation and migration with a VEGF dependency but did not effect proliferation. SB-3CT inhibited the mutant-CM- and VEGF-stimulated tube formation but had no effect on the mutant-CM, VEGF and active MMP2-stimulated migration. The combined use of active MMP2 and VEGF resulted in a synergistic migration of endothelial cells.
Conclusions: :
Conclusions: S156C-TIMP3 potentiates VEGF-induced tube formation and migration via elevated active MMP2 in an enzymatic activity-dependent or -independent manner, respectively. These data provide new insight into the function of MMP2 in endothelial cells, and suggest that anti-VEGF therapy combined with selective active MMP2 targeting may be a potential improved strategy for prevention and treatment of CNV in SFD or in AMD.
Keywords: age-related macular degeneration • retinal pigment epithelium • mutations