Abstract
Purpose :
Glucocorticoids function via activation of the glucocorticoid receptor alpha (GRα), a mechanism that can be attenuated by an alternative spliced glucocorticoid receptor known as GR. Steroid use is linked to elevated intraocular pressure in ~30% of the human population. In addition, higher levels of TGFβ2 have been reported in the aqueous humor of glaucoma patients. In the current study, we investigated the effect of dexamethasone treatment on known glaucomatous markers in trabecular meshwork cells overexpressing GRα and GRβ.
Methods :
Stably-transfected RFP-GRα and RFP-GRβ TM cell-lines were developed. Levels of plasminogen activator inhibitor-1 (PAI-1), lysyl oxidase (LOXL), collagen-I, collagen IV, and TGFβ2 in cells treated overnight with vehicle (ethanol) or dexamethasone (DEX) were studied using western blot in concentrated media.
Results :
DEX treatment increased PAI-1, LOXL, pro-collagen-I, and collagen IV in TM5 and RFP-GRα-TM5 cells. However, DEX-induction of such proteins was inhibited in RFP-GRβ-TM5 cell-line. Overexpression of GRα and β receptors increased latent inactive TGFβ2 levels and a novel 30kDa isoform was detected in RFP-GRβ-TM5 cells only. DEX treatment inhibited the production of the active 13kDa TGFβ2 in all TM5 cell-lines.
Conclusions :
Steroid treatment inhibited mature TGFβ2 production in TM cells. GRβ appears to exert novel actions in the trabecular meshwork independent of GRα.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.