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Andrew J. O. Smith, Michael Wormstone; MMPs facilitate latent TGFβ1 activation in the human lens: implications for PCO. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2024.
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© 2017 Association for Research in Vision and Ophthalmology.
Posterior capsule opacification (PCO) is the most common complication of cataract surgery and leads to secondary loss of vision in a large proportion of patients. Transforming growth factor beta (TGFβ) signalling induced as a consequence of the wound healing response to surgery is implicated in PCO. TGFβ is produced in a latent form and requires activation before signalling can take place. However, the mechanisms involved in its activation are not fully understood in the human lens. Here, we investigate the role of matrix metalloproteinases (MMPs) in TGFβ1 activation in human lens cells.
The human lens epithelial cell line FHL124 which has a 99.5% similarity in gene expression to native lens epithelium was used as the experimental system. MMPs were inhibited with the broad-spectrum MMP inhibitor GM6001 (12.5μM) for 1 hour prior to addition of latent TGFβ1 (10ng/ml). Smad2/3 nuclear translocation was assessed by immunocytochemistry (2 hours post-latent TGFβ1 treatment), expression of the myofibroblast cell marker, α-smooth muscle actin (α-SMA), was assessed by western blot and matrix contraction by a patch contraction assay (both 4 days post-latent TGFβ1 treatment). ImageJ 1.46r software was used to perform image analysis on immunocytochemistry, western blots and cell patch contraction assays.
Latent TGFβ1 addition resulted in Smad2/3 nuclear translocation in FHL124 cells, inducing a peak nuclear signal 2 hours post-treatment, indicating that activation had taken place. Interestingly, this TGFβ1-induced Smad2/3 nuclear translocation was significantly reduced when MMPs were inhibited. In terms of α-SMA, latent TGFβ1 caused increased expression at experimental end point, but again this increase was countered with GM6001. Furthermore, addition of latent TGFβ1 induced significant matrix contraction which was suppressed in the presence of the MMP inhibitor GM6001.
Latent TGFβ1 can be activated by lens epithelial cells and this can give rise to Smad2/3 signalling, a myofibroblast phenotype and matrix contraction. The activation of TGFβ1 appears to involve MMPs and this family of proteases can serve as a useful target in PCO management and prevention.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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