Abstract
Purpose :
Antioxidant supplementation could be a potent adjunctive therapy for many ocular diseases in dogs, including glaucoma. However, a wide variety of antioxidant formulations are available, without direct experimental proof supporting their benefits. In this study, we assess the effect of an oral antioxidant formulation on ocular parameters in dogs, and on trabecular meshwork (TM) cells in vitro.
Methods :
Twelve heathy dogs received an antioxidant formulation (EyeCare II, Meni-One, Nagoya, Japan) containing curcumin, proanthocyanidins, vitamin E, astaxanthin and brewer’s yeast, during 3 months (day 30 to day 120). Ocular parameters (intraocular pressure (IOP), break up time (BUT), Schirmer II test) were measured twice before supplementation start as baseline reference values (day 0 and day 30), and at day 90 and 120. Conjunctival cytology, glutathione peroxidase (GP) activity and C reactive protein level in plasma were assessed before and after supplementation. Human primary TM cells were treated with 0.5% boric acid (BA) in culture medium alone and in presence of 3 increasing dilutions of the antioxidant formulation. After 3 and 24h, cell death was analyzed by fluorescence microscopy using calcein-AM and propidium iodide staining. Cleaved caspase 3 and BAX proteins expression in TM cells were analyzed by western blotting.
Results :
Schirmer II test, BUT and IOP didn’t vary over the study period. Conjunctival cytology confirmed the absence of ocular inflammation or epithelial cells anomalies. After 3 months-supplementation, GP activity was significantly increased (+27.6%, p=0.003). In vitro, co-incubation with antioxidant formulation dilutions decreased significantly the percentage of TM cells death induced by 0.5% BA after both 3h (-24.4 to -34.1%) and 24h incubation (-19.3 to -34.0%, p<0.0001). Cleaved caspase 3 and BAX expression were increased after 30min, 1h and 3h of BA treatment. Co-incubation with antioxidant formulation significantly decrease cleaved caspase 3 and BAX expression at these time points.
Conclusions :
Human TM cells apoptosis triggered by BA treatment is efficiently blocked by the antioxidant formulation in vitro. Ocular parameters in healthy dogs were not altered by supplementation, whereas GP plasmatic activity was significantly enhanced.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.