Abstract
Purpose :
To investigate the effect of SB772077B (SB77) on aqueous outflow facility (OF), flow pattern and regulation of cytoskeletal proteins, focal adhesion and extracellular matrix (ECM) in human eyes.
Methods :
For establishing the perfusion-cultured human anterior segment ex vivo model (HOCAS), paired human donor eyes were dissected and the anterior segments were perfused continuously with medium containing antibiotics at 3µl/minute to achieve a stable baseline OF. One eye of each pair was exchanged with medium containing SB77 (0.1 µM, 10 µM, or 50 µM). Contralateral eyes received medium with vehicle. IOP was monitored for 24 h post treatment. The hydrodynamic pattern of aqueous outflow was analysed by labelling aqueous outflow tissue with red fluorescent microspheres. By immunostaining in primary human trabecular meshwork (HTM) cells, the effect of SB77 on cell morphology, actin stress fibers, focal adhesions, ECM and myosin light chain phosphorylation (p-MLC) status was evaluated and compared with the rho kinase inhibitor Y27632. The cytotoxicity of SB77 was assessed by MTT and TUNEL assay. Rho activation status was determined by pull-down assay.
Results :
SB77 treatment caused dose-dependent increase in OF. Following 24 h treatment, SB77 increased OF by 15% at 0.1µM (N=6), by 27% at 10 µM (N=8; p<0.05) and by 40% at 50 µM (N=8; p<0.005) as compared to vehicle control. Visualization of the hydrodynamic outflow pattern revealed an overall increase in tracer quantity and increased TM thickness with SB77 treatment as compared to the control group. Treatment with SB77 (50µM) showed no evidence of cytotoxicity and caused a significant reduction in the expression of fibrotic markers and p-MLC as compared to Y27632 in HTM cells. The amount of activated RhoA was also significantly reduced by SB77 (p<0.05).
Conclusions :
The present findings indicate that SB77 was effective in enhancing OF in an ex vivo HOCAS model, consistent with the increase in TM thickness. It is also effective in reducing fibrotic markers as compared to Y27632 in vitro. Hence, SB77 may be a potential clinical candidate for the management of glaucoma.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.