Abstract
Purpose :
Diabetic Retinopathy (DR), the ocular complication of Diabetes Mellitus, affects primarily working-age adults and is responsible for 5% of blindness cases. Treatment options are limited and often poorly effective.
Inflammation and an imbalance between anti- and pro-angiogenic factors are key in DR [1-3, 6] and can be therapeutic targets. Pyrogallol-O-sulfate (Pyr-sulf) is a compound resulting from the metabolization of polyphenols present in berries that was shown to cross the blood-brain barrier and to possess anti-inflammatory properties [4, 5]. We hypothesize that DR can benefit from Pyr-sulf, and hence tested its effect on restoring the balance between pro- and anti-angiogenic factors and on inflammation markers of DR.
Methods :
D407, a retinal pigment epithelium (RPE) cell line, was cultured in normoglycemic and hyperglycemic conditions, under normoxia or hypoxia. Treatment with Pyr-sulf (6.5μM) was performed for 24 h and RNA and protein extracted for RT-qPCR and Western blot, respectively, for analysis of VEGF, PEDF, GLUT1 (glucose transporter) and production of inflammation markers (Il-1B and Il-8).
In vivo, administration of Pyr-sulf 6.5uM by single intravitreal or subretinal injections in Ins2Akita diabetic mice was followed by extraction of the retina 2 weeks after injection for protein analysis by Western blot for VEGF, PEDF, GLUT1, with GFAP and Iba1 as inflammation markers.
Results :
Treatment with Pyr-sulf does not affect mRNA levels of PEDF and VEGF in RPE cells, but VEGF protein levels decrease after Pyr-sulf treatment in hyperglycemia and normoxia, compared with untreated cells (n=4, p=0,0128). Il-1b and Il-8 levels seem to decrease (n=3) but are not significant in RPE cells. In vivo, Pyr-sulf does not affect PEDF levels, but decreases the expression of VEGF and Iba1 in 4-, 6- and 8-month old diabetic animals compared with WT (n=3, p>0.05).
Conclusions :
Pyrogallol-O-sulfate treatment results in a decrease in the expression of pro-angiogenic and pro-inflammatory factors, highlighting its potential benefit in diabetic retinopathy.
[1] Am J Ophthalmol 1994, 118, 445-450. [2] Biochimie 2018, 155, 104-108. [3] Molecular Vision 2016, 22, 761-70. [4] Eur J Nutr 2017, 1–18. [5] Food Chemistry 2017, 215, 274-283. [6] J Mol Endocrinol 2016, 37, 1-12.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.