Related Experiment Videos
Matrix metalloproteinases and metalloproteinase inhibitors in choroidal neovascular membranes
B Steen1, S Sejersen, L Berglin
1Department of Ophthalmology, St. Erik's Eye Hospital, Karolinska Institute, Stockholm, Sweden.
Purpose:
Matrix metalloproteinases (MMP) are a family of extracellular matrix degrading enzymes associated with the development of neovascularization. To investigate the possible role of these enzymes in choroidal neovascularization, the mRNA expression of MMPs and tissue inhibitors of metalloproteinases (TIMPs) were analyzed in subfoveal fibrovascular membranes from patients with age-related macular degeneration (AMD).
Methods:
Surgically removed subfoveal fibrovascular membranes from five eyes were analyzed for the expression of MMP and TIMP mRNA. In situ hybridization anti-sense and sense riboprobes were generated using DNA complementary to human collagenase (MMP-1), 72 kDa gelatinase (MMP-2), stromelysin (MMP-3), 92-kDa gelatinase (MMP-9), TIMP-1, TIMP-2, and TIMP-3. Vascular endothelial cells were detected using immunostaining for von Willebrand factor.
Results:
MMP-2 and MMP-9 mRNA were detected in all specimens. Most of the membranes also expressed TIMP-1 and TIMP-3 mRNA, and two of the membranes expressed TIMP-2 mRNA. MMP-2, TIMP-1, and TIMP-2 mRNA had a similar overall distribution that was relatively uniform within the vascularized membrane stroma. MMP-2 expression appeared to be localized mainly to the vascular endothelial cells, whereas TIMP-1 and TIMP-3 were detected in other cell types such as fibroblastlike cells. MMP-9 expression was distinctly expressed by cells at the margins of the membranes and often in proximity to a thickened Bruch's membrane-like layer under the retinal pigment epithelial cells. TIMP-3 mRNA was strongly expressed within the retinal pigment epithelial cell layer and also in the stroma of one membrane. None of the membranes showed detectable MMP-1 or MMP-3 expression.
Conclusions:
The results support a role for MMPs in the development of choroidal neovascularization in AMD. The localization of MMP-2 and MMP-9 to the areas of new vessel formation and to the enveloping Bruch's-like membrane, respectively, suggests that MMP-2 and MMP-9 may be cooperatively involved in the progressive growth of choroidal neovascular membranes in AMD.
Insights
Matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) are involved in choroidal neovascularization in age-related macular degeneration (AMD). MMP-2 and MMP-9 were detected in membranes, suggesting a role in AMD progression.
Area of Science:
- Ophthalmology
- Molecular Biology
- Cell Biology
Background:
- Matrix metalloproteinases (MMPs) are enzymes that degrade extracellular matrix.
- MMPs are implicated in neovascularization, a process involved in age-related macular degeneration (AMD).
Purpose of the Study:
- To investigate the role of MMPs and TIMPs in choroidal neovascularization in AMD.
- Analyze mRNA expression of MMPs and TIMPs in subfoveal fibrovascular membranes from AMD patients.
Main Methods:
- Surgically removed subfoveal fibrovascular membranes from five AMD eyes were analyzed.
- In situ hybridization was used to detect mRNA expression of MMP-1, MMP-2, MMP-3, MMP-9, TIMP-1, TIMP-2, and TIMP-3.
- Immunostaining for von Willebrand factor identified vascular endothelial cells.
Main Results:
- MMP-2 and MMP-9 mRNA were detected in all analyzed membranes.
- TIMP-1 and TIMP-3 mRNA were present in most membranes; TIMP-2 mRNA was found in two.
- MMP-2 localized to vascular endothelial cells, while MMP-9 was found at membrane margins.
Conclusions:
- Results support a role for MMPs in choroidal neovascularization development in AMD.
- MMP-2 and MMP-9 localization suggests cooperative involvement in the growth of choroidal neovascular membranes in AMD.