Abstract
Purpose: :
To compare the effect of latanoprost, bimatoprost, and unoprostone on the protein and enzyme activity levels of matrix metalloproteinases (MMPs) and the protein levels of tissue inhibitors of metalloproteinases (TIMPs) in human trabecular meshwork (TM) endothelial cells.
Methods: :
Cultures of human TM cells isolated from corneoscleral rims of 13 donors were grown to confluence. Following 1 day of incubation with serum free media, the cells were treated with vehicle control (0.03% ethanol), or the prostaglandin analogues (PGAs) latanoprost (0.03 µg/ml), bimatoprost (0.01 µg/ml), or unoprostone (0.145 µg/ml) for 24 hours. Western blotting was used to assess relative changes in pro-MMP and TIMP protein levels. Zymography was used to assess relative changes in enzyme activity of MMPs-1, -2, -3, and -9. Cell lines from five donors were used to determine the relative effects for each of the MMPs and TIMPs. Repeated immunoblots revealled a variability of approximately 10%. GAPDH served as an endogenous control. Results are presented as the mean ± SEM.
Results: :
All three PGAs had similar effects on pro-MMPs. Pro-MMP-1 increased approximately 45% ± 15% to all of the PGAs. Latanoprost and bimatoprost increased pro-MMPs-3 and -9 by 36% ± 20%, and 68% ± 17%, respectively. Unoprostone increased pro-MMP-3 by 16% ± 19% and pro-MMP-9 by 42% ± 19%. Pro-MMP-2 and MMP-24 remained within 10% of control for all PGAs.Latanoprost, bimatoprost and unoprostone increased the activity of MMP-9 by 20% ± 2%, 17% ± 2% and 14% ± 1%, respectively. All PGAs increased the intermediate form of MMP-1 by 14% ± 1%. The activity of MMP-2 did not change following all PGAs. The activity of MMP-3 was not identified on zymography.Latanoprost decreased TIMP-1 by 42% ± 4% while bimatoprost increased TIMP-1 by 88% ± 34%. TIMP-2 expression increased an average of 33% ± 7% and 83% ± 42% following latanoprost and bimatoprost, respectively. Unoprostone did not affect the level of TIMPs-1 and -2. All PGAs did not change TIMP-3 expression. Latanoprost, bimatoprost, and unoprostone increased TIMP-4 by 76% ± 37%, 200% ± 133%, and 69% ± 28%, respectively.
Conclusions: :
Latanoprost, bimatoprost, and unoprostone increased MMPs-1, -3, and -9 with comparable effects. Latanoprost and bimatoprost concurrently increased TIMPs-2, and -4 while unoprostone increased only TIMP-4. Latanoprost decreased TIMP-1. Given that PGAs have a minimal effect on conventional outflow, our findings may indicate a very important role of TIMP-4 in determining the overall MMP:TIMP ratio that governs ECM turnover.
Keywords: trabecular meshwork • enzymes/enzyme inhibitors • gene/expression