Abstract
Purpose :
Glucocorticoids are known to have a negative effect on subretinal fluid accumulations in central serous chorioretinopathy (CSC). This disease involves typically the RPE/choriocapillaris complex but the exact pathophysiology is still unidentified. Here we wanted to evaluate the effects of Hydrocortisone on the integrity of cellular junctions and the major regulators of subretinal H20 transport in RPE cells.
Methods :
Adult human RPE cells (Passages 1-3) were seeded on to poly-L-lysine-coated 8-well chamber slides and allowed to differentiate in low serum (2% v/v) medium for at least 8 weeks. Porcine RPE-Choroid-Sclera explants were preincubated overnight on culture inserts (0.45 µm pore size) with the RPE-side facing upwards. Cells and the basal side of explants were incubated with Hydrocortisone (0-5-50-500 nM) for 1 day. Protein distribution was analyzed by immunostaining and -blotting.
Results :
Hydrocortisone led to a significant increase in the levels of beta-Catenin, N-Cadherin, and ZO-1 at cellular junctions and the expression of Na/K-ATPase in human RPE cells. A considerable increase was detected in the levels of Na/K-ATPase and the water channel Aquaporin-1 in both the apical and the basolateral membranes as well as the expression of Na/K/2Cl cotransporter (NKCC1) in the lateral membrane of RPE cells in porcine explants incubated with Hydrocortisone.
Conclusions :
Exposure to Hydrocortisone can strengthen the integrity of RPE junctions while disrupting the polarized, mainly apical distribution of Na/K-ATPase. The latter event might lead to a failure in the establishment of the ionic gradient essential for the transepithelial H2O transport towards choroid. This may in turn result in an increased accumulation of subretinal fluid in CSC and by that in a worsening of the disease, especially if this mechanism is already significantly compromised by CSC pathophysiology.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.