Green tea catechins alleviate autoimmune symptoms and visual impairment in a murine model for human chronic intraocular inflammation by inhibiting Th17-associated pro-inflammatory gene expression

Abstract

Autoimmune uveitis is a sight-threatening disease mainly caused by dysregulation of immunity. We investigated the therapeutic effects of green tea extract (GTE) and its major component, epigallocatechin-3-gallate (EGCG), on a murine model of experimental autoimmune uveoretinitis (EAU). Oral administration of GTE, EGCG, dexamethasone, or water, which started 5 days before the induction, was fed every two days to each group. On day 21 post induction, 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 (RCT) and major retinal vessel diameter were measured on OCT sections and FFA images, respectively. Comparing to water-treated EAU animals, GTE attenuated uveitis clinical manifestations, RCT increase (1.100 ± 0.013 times vs 1.005 ± 0.012 times, P < 0.001), retinal vessel dilation (308.9 ± 6.189 units vs 240.8 units, P < 0.001), ERG amplitudes attenuation, histopathological ocular damages, and splenomegaly in EAU mice. The therapeutic effects of GTE were dose dependent and were comparable to dexamethasone. EGCG, a major active constituent of GTE, partially alleviated uveitic phenotypes including recovering visual function. Th-17 associated pro-inflammatory gene [interleukin 1 beta (IL-1β), IL-6, IL-17A, and tumor necrosis factor alpha (TNF-α)] expressions were down regulated by GTE and EGCG treatments, which showed no detectable morphological defects in liver and kidney in non-induced and EAU mice. Our findings suggest that GTE consumption can serve as a potent therapeutic agent as well as a food supplement for developing alternative treatments against autoimmune uveitis.

Antioxidant Activity and Main Chemical Components of a Novel Fermented Tea

“…Tea polyphenols have attracted huge interest because of their presumed associated health properties [7,8]. Over the past few years, numerous studies have indicated that catechins and other polyphenols in tea exhibit powerful antioxidant activities [9].…”

Epigallocatechin Gallate Slows Retinal Degeneration, Reduces Oxidative Damage, and Modifies Circadian Rhythms in P23H Rats

“…Our study focused on the effect of the main catechin of green tea, EGCG, administered to an animal model of RP, the P23H rat. Previous studies demonstrated the ability of EGCG to reach retinal tissue and act as an antioxidant, diminishing levels of oxidative stress and apoptosis and improving visual function [29,38,[53][54][55]. The P23H rat was created by the incorporation of a mutated rhodopsin transgene from C57BL/6J mouse in an albino wild-type rat (Sprague-Dawley (SD)) resulting in a homozygous transgenic animal.…”

Immunomodulatory Effects of Green Tea Polyphenols

“…Compared to a water-treated experimental autoimmune uveoretinitis (EAU) murine model, GTE attenuated clinical manifestations of uveitis, increased retinal-choroidal thicknesses (RCT) (1.100 ± 0.013 times vs1.005 ± 0.012 times, P < 0.001) and retinal vessel dilation (308.9 ± 6.189 units vs 240.8 units, P < 0.001) in a dose-dependent manner [ 96 ]. EGCG could also partially alleviate uveitic phenotypes and recover visualfunction in the murine model of EAU [ 96 ]. The treatment of GTE and its major component EGCG upregulated Th-17 associated pro-inflammatory genes, such as IL-1β, IL-6, IL-17A, and TNF-α [ 96 ].…”

“…EGCG could also partially alleviate uveitic phenotypes and recover visualfunction in the murine model of EAU [ 96 ]. The treatment of GTE and its major component EGCG upregulated Th-17 associated pro-inflammatory genes, such as IL-1β, IL-6, IL-17A, and TNF-α [ 96 ]. GTE consumption serves as a potent therapeutic agent and a food supplement to develop alternative treatments against autoimmune uveitis [ 96 ].…”