Preventive effect of chrysin on experimental autoimmune uveitis triggered by injection of human IRBP peptide 1-20 in mice.

Uveitis is a common cause of blindness worldwide. Experimental autoimmune uveitis (EAU) is an animal model of noninfectious uveitis. Chrysin (5,7-dihydroxyflavone) is a member of the flavonoid family and has anti-inflammatory effects. We immunized C57BL/6J mice with human interphotoreceptor retinoid-binding protein peptide 1-20 to induce EAU. Chrysin was administered intragastrically at 25 mg/kg daily to the chrysin-treated mice from 3 days before immunization to 21 days after immunization. Vehicle was administered to the mice in the control group according to the same protocol. Lower clinical and histopathological scores, increased integrity of the blood-retinal barrier (BRB) and higher expression of tight junction proteins were observed in the chrysin-treated mice. Chrysin significantly decreased the proportions of Th1, Th17 and CD4+ CD3+ CD62L+ Th0 cells, and increased the proportion of Treg cells. Both macrophage infiltration and the expression of inducible nitric oxide synthase in the retina were efficiently inhibited by chrysin treatment. In chrysin-treated mice, the expression of interferon-γ, interleukin (IL)-17A, IL-6, IL-1β and tumor necrosis factor-α was reduced in the retina, whereas higher levels of transforming growth factor-β were detected. Furthermore, NF-κBp65 was downregulated after chrysin treatment. In conclusion, as an anti-inflammatory molecule, chrysin exerts a preventive effect on EAU by modulating the balance among helper T-cell subsets and suppressing ocular inflammation, thereby maintaining the integrity of the BRB.