Abstract
Purpose :
Uveitis is a blinding disease caused by ocular inflammation. However the current standard therapy, corticosteroid, has many potential side effects such as IOP induction. Therefore alternative effective treatments are desirable. Green tea extract (GTE) has been extensively studied as an herbal remedy due to its antagonistic effects against oxidation, inflammation, and angiogenesis. GTE exerted anti-inflammatory activities as shown in our previous studies in an acute infectious uveitis model. The present work investigates the anti-inflammatory effects of GTE on non-infectious intraocular inflammation in an experimental autoimmune uveoretinitis (EAU) model.
Methods :
EAU was induced in 7-week old female C57BL/6J mice by immunization with hIRBP. Control animals were injected with PBS. Oral administration of GTE, dexamethasone, or water, which started 5 days before the EAU induction, was fed every two days to each group of animals. On day 21 post immunization, the eyes were examined by confocal scanning laser ophthalmoscopy, optical coherence tomography (OCT), fundus fluorescein angiography (FFA) and electroretinography (ERG) prior to sacrificing the animals for histological assessments and gene expression studies. Retinal-choroidal thicknesses were measured on OCT sections. FFA images were analyzed to determine the perfusion area of major retinal vessels. Mann-Whitney test was used for statistical analysis.
Results :
GTE treatment improved the clinical manifestations of posterior ocular inflammation consisting of infiltrating cells, vasculitis, and retinal damage. The fold changes of retinal-choroidal thickness caused by inflammatory edema were reduced in GTE-treated animals (0.99±0.02) compared to the water-treated group (1.07±0.02, p<0.01). Major retinal vessel perfusion areas were also reduced by GTE (p<0.05), indicating alleviation of inflammatory vasodilatation. ERG of GTE-treated animals showed milder reductions of both scotopic and photopic amplitudes than in the water-treated EAU animals, implying a relief of functional disruption in vision caused by the EAU induction. GTE suppressed expression of inflammatory genes, such as tumor necrosis factor-alpha (TNF-α), in the retina (p<0.05). Remission of the EAU as a result of GTE treatment was comparable to that in dexamethasone-treated EAU mice (P>0.05).
Conclusions :
Our findings show that GTE is a potent anti-inflammatory agent against the inflammation of autoimmune uveitis.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.