Glucocorticoid-induced leucine zipper overexpression inhibits lipopolysaccharide-induced retinal inflammation in rats
Glucocorticoid-induced leucine zipper (GILZ) mediates several effects of glucocorticoids and has important anti-inflammatory properties. Here, we explored the role of GILZ in inhibiting retinal inflammation. Endotoxin-induced uveitis (EIU) was established in rats by intravitreal injection of lipopolysaccharide (LPS). GILZ levels decreased in the EIU retina after LPS injection. Retinal GILZ was downregulated by recombinant lentivirus-delivered short-hairpin RNA targeting GILZ (shRNA-GILZ-rLV) and upregulated by recombinant lentivirus-mediated GILZ overexpression (Oe-GILZ-rLV). GILZ silencing attenuated the anti-inflammatory effects of intravitreal injection of triamcinolone acetonide (TA) in the EIU retina, as demonstrated by increased retinal interleukin (IL)-1β, monocyte chemoattractant protein (MCP)-1and intercellular cell adhesion molecule-1 expression at 18 h after TA injection. A Bio-Plex cytokine assay and western blotting demonstrated that GILZ overexpression inhibited the effects of LPS, downregulating retinal IL-1β, MCP-1, MIP-1α, and IL-17 and inhibiting LPS-induced activation of the retinal toll-like receptor 4–myeloid differentiation factor 88 signaling pathway. At 48 and 72 h after LPS injection, the clinical score of inflammation was significantly lower in Oe-GILZ-rLV–transfected eyes than in blank-rLV–transfected eyes. Histological examination showed a 67.85% reduction of infiltrating inflammatory cells in the anterior chamber and a 58.97% reduction in vitreous cavity of Oe-GILZ-rLV transfected eyes at 48 h after LPS injection. Taken together, our results suggest that GILZ is a novel therapeutic target for the treatment of retinal inflammatory diseases.