Abstract
Purpose :
Long-term use of glucocorticoids (GCs) may increase intraocular pressure (IOP) in about 40% of the general population. This IOP elevation is due to GC-induced pathological changes in the trabecular meshwork (TM). Published studies show that ABCA1 is associated with glaucoma susceptibility. The inhibitor of ABCA1 decreases outflow facility while the agonist of ABCA1 increases outflow facility and IOP in perfusion cultured human eyes and mouse eyes, respectively. Here, we determined if ABCA1 is involved in lipid metabolism and ECM accumulation induced by GCs in the TM.
Methods :
Several characterized primary human TM (pHTM) cell strains and the transformed GTM3 cell line were used. The cells were treated with 100nM dexamethasone (DEX) with or without RU 486 (the DEX inhibitor) for 3-5 days. Some cells were transfected with ABCA1 siRNA (10nM) or non-targeting (NT) siRNA with or without DEX/RU486. At the end of the treatment, conditioned medium (CM) and whole cell lysates (WCL) were collected for Western immunoblotting. Some cells were used for oil red staining (for liquid deposition) or the cholesterol /cholesterol ester Glow assay kit.
Results :
In both pHTM and GTM3 cells, DEX induced the expression of ABCA1 which was inhibited by co-treatment with RU486. Oil red staining showed that DEX induced lipid accumulation in TM cells, and this induction was also inhibited by RU486. By knocking down ABCA1 using siRNA, we found that there was an increase in fibronectin and collagen I in TM cells. Besides, ABCA1 knockdown increased DEX-induced cholesterol /cholesterol ester levels in TM cells.
Conclusions :
The expression of ABCA1 is induced by GC signaling in the TM. Since ABCA1 knockdown increased lipids and ECM in the TM, ABCA1 seems to be “beneficial” to the TM.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.