Abstract
Purpose :
To investigate the utility of GDF-15 in aqueous humor as a biomarker for glaucoma in a hypertonic saline-induced rat model.
Methods :
Glaucoma was induced by injecting 0.05 ml of 2M NaCl into the episcleral vein of the right eye (OD) of Long Evans rats. The untreated left eye (OS) served as a control. Aqueous humor (AH) samples were collected on days 1, 3, 7, and 14 days post injection with hypertonic saline and analyzed for GDF-15 content. AH samples were measured using a rat GDF-15 ELISA.
Results :
Following injection with hypertonic saline into the episcleral vein, GDF-15 levels increased on day 1 and day 3 post injection with means of 530 ± 158 pg/ml (SEM) on day 1 and 374 ± 58 pg/ml (SEM) on day 3, compared to untreated control AH with a mean of 114 ± 9 pg/ml (SEM). Due to the variation in the data the increase in PDGF-15 on day 1 and Day 3 post injection were not significantly different from control data. However, on day 7 post injection the GDF-15 levels in AH increased with a mean of 1,122 pg/ml ± 339 (SEM) and was significantly different from control GDF-15 (ANOVA with Tukey's multiple comparison test P< 0.05). GDF-15 levels on Day 14 post injection decreased with a mean of 188 ± 68 pg/ml (SEM) and was not significantly different from untreated control GDF-15 levels.
Conclusions :
GDF-15 has been described as a potential biomarker for glaucoma using a chronic mouse glaucoma model and a rat optic nerve crush model. In this study we demonstrate that GDF-15 levels significantly increase in AH using a rat hypertonic saline induced model of glaucoma. The increase in GDF-15 occurs on day 7 post injection with hypertonic saline and occurs before any significant change in intraocular pressure (IOP) or any significant loss of retinal ganglion cells. Further studies using agents that protect against the loss of retinal ganglion cells and determining if these agents prevent or modify the increase in GDF-15 will help establish the use of GDF-15 as a glaucoma biomarker.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.