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S.T. Wang–Su, B.J. Wagner; Down–Regulation of Matrix Metalloproteinases in Explanted–IOLs and HLE B–3 Cells by Proteasome Inhibition . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2864.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Changes in lens capsule structure during posterior capsular opacification (PCO) depend on remodeling of the extracellular matrix by matrix metalloproteinases (MMPs). MMPs in turn are regulated by growth factors and cytokines such as NFΚB, which in turn are controlled by the ubiquitin–proteasome pathway. In this study we determined the effect of proteasome inhibition on the expression of MMPs in lens cells. Methods: Six capsular bags with IOLs were prepared from human donor eyes and cultured in 1 ml serum free DMEM medium in 12 well dishes. They were treated for 10 days with 1 or 10 ng/ml TGF–ß, with or without 10 µM MG132 (proteasome inhibitor). The medium was sampled and replaced every 2 days and analyzed for MMP 2 and MMP 9 activities by SDS–PAGE zymography. HLE B–3 cells were treated for 72 hrs with 1 ng TGF–ß, with or without 2.5 µM MG132, and the medium collected and analyzed as described above. Results: Untreated IOL capsular bag cultures showed varying baseline levels of MMP 2 and 9. TGF–ß treatment caused a small increase in MMP 2 and a large increase in MMP 9 over 10 days of culture at both TGF–ß concentrations. Cotreatment of capsular bags with MG132 in addition to TGF–ß prevented the increase in MMPs seen with TGF–ß alone. During the 10 day incubation with 10 µM MG132, production of MMPs was gradually reduced (10 ng TGF–ß) or eliminated (1 ng TGF–ß). In the presence of MG132 alone, MMPs were undetectable within 2 days. Medium from untreated HLE B–3 cells (cultured in the presence or absence of serum) contained only MMP 2 activity. Addition of TGF–ß resulted in induction of MMP 9 activity, but MMP 2 activity increased only slightly. Co–treatment with MG132 resulted in decreased MMP 2 and undetectable MMP 9. MG132 alone reduced MMP 2 below baseline levels. Conclusions: In both IOL capsular bag and HLE B–3 lens cell cultures, TGF–ß induces elevated MMP levels, particularly the pathophysiological MMP 9. In co–treatment experiments with IOL capsular bag or HLE B–3 cultures, MG132 inhibited TGF–ß induced increases in MMP activity, suppressing MMP 2 and eliminating MMP 9. These results suggest possible use of proteasome inhibitors to prevent PCO.
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