Fig. 1

XBD173 treatment of light-exposed mice prevents microglia reactivity. a Light exposure regimen and mode of XBD173 administration. Representative photomicrographs show retinal sections (b–d) and flat mounts (e–j) stained with IBA1 (green) and DAPI (blue). In control retinas, microglial cells were located in the OPL, IPL, and GCL (b, e, h). Light-exposed retinas injected with vehicle control showed a massive thinning of the ONL and many amoeboid-shaped, reactive microglia in the ONL and the subretinal space (c, f, i). Compared to vehicle controls, the ONL of XBD173-treated retinas appeared markedly preserved and less amoeboid microglia were detectable in the ONL and the subretinal space (d, g, j). The total number of Iba1-positive microglial cells in the ONL (k) and the subretinal area (l) after light damage was significantly reduced in the XBD173 therapy group. Data show mean ± SEM (control n = 3, light exposure and vehicle treatment n = 6, light exposure and XBD173 treatment n = 12 sections). The percentage of CD11b-positive cells in the retina as determined by flow cytometry was strongly reduced by XBD173 treatment in representative FACS plots (m–o) and quantitative analyses of n = 3–4 retinas (p). ONL outer nuclear layer, OPL outer plexiform layer, INL inner nuclear layer, IPL inner plexiform layer, GCL ganglion cell layer. *p < 0.05; **p < 0.01; ***p < 0.001. Scale bar 50 μm