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Guorong Li, W Michael Dismuke, Iris Navarro, Kristin M Perkumas, David F Woodward, W Daniel Stamer; Secretion profile of human trabecular meshwork cells following recovery from prolonged corticosteroid treatment. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3273.
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© ARVO (1962-2015); The Authors (2016-present)
Corticosteroid-induced ocular hypertension can be reproduced in mice, which display all four hallmarks of the human disease. Interestingly, upon removal of corticosteroids, intraocular pressure rapidly returns to normal. The purpose of this study was to examine the changes in protein secretion that occur in human trabecular meshwork (HTM) cells over time following withdrawal from prolonged corticosteroid treatment.
Three characterized HTM cell strains (HTM120, HTM123 and HTM124) were cultured in 6-well plates with DMEM containing 10% FBS until reaching confluency. The cells were differentiated by culturing in DMEM containing 1% FBS for at least one additional week. The cells were then treated with dexamethasone (Dex) 100 nM in 1% FBS supplemented medium for 1 or 4 weeks. The cell culture supernatant was collected 3 times/week. The secretion of myocilin (MYOC), matrix metalloproteinase-2 (MMP2) and fibronectin (FN) were analyzed by Western Blot.
The recovery profile over time of analyzed proteins were vastly different: MMP2 protein levels were reduced ~40% by Dex treatment (p<0.01). Interestingly, MMP2 returned to normal levels following Dex withdrawal within a week, even after four weeks of treatment. In contrast, a significant increase in MYOC levels (up to 600%) remained elevated two weeks after Dex withdrawal, even after only one week of treatment. Interestingly, FN showed a delayed response to one week Dex treatment, not reaching significantly higher levels until one week after withdrawal. However, a significant ~183% increase in FN was observed following four weeks of Dex, not returning to normal levels until four weeks post withdrawal.
Results suggests that the rapid return of IOP in mice following cessation of corticosteroid treatment is due to recovery of normal MMP secretory function by HTM cells and homeostatic extracellular matrix degradation.
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