ATF4 regulates retinal MCP-1 expression and leukocyte infiltration in vivo. A). Wild type (WT) or heterozygous ATF4 knockout (KO) mice received intravitreal injection of 250 ng of LPS in one eye and PBS as control in the contralateral eye. Twenty-four hours after injection, retinal MCP-1 expression was determined by qPCR (n = 5). Results were expressed as mean ± SD. *P < 0.05 vs. WT + PBS; ++ P < 0.01 vs. WT + LPS. B-D). C57/B6J mice received intravitreal injection of 1 μl of Ad-ATF4 or Ad-Ctrl (109 viral particles). After 5 days, retinas were harvested and MCP-1 level was measured by ELISA (B). Results are expressed as mean ± SD, n = 5. *P < 0.05 vs. Ad-Ctrl. Leukocyte infiltration into the vitreous and retina was analyzed by H&E staining of paraffin sections (C). and immunofluorescence analysis for monocyte/macrophage marker CD11b (D). GCL: ganglion cell layer, INL: inner nuclear layer, ONL: outer nuclear layer. Black arrows indicate inflammatory cell infiltration into the vitreous (C) and white arrows indicate CD11b positive cells in the retina (D). Images were representative of 3 mice in each group.