Figure 8

In vivo retinal microglia and Müller cell responses to retinal microglial activation induced by intravitreal injection of lipopolysaccharide (LPS). In vivo activation of retinal microglia was induced by intravitreal injection of different total amounts of LPS (0 μg, 0.1 μg, 0.5 μg, 2 μg) dissolved in 1 × PBS. Eyes injected with only 1 × PBS (0 μg LPS) served as controls (left column). Animals were sacrificed and enucleated 3 days after intravitreal injection and cryosections prepared from the globes. (A) Iba1 immunolabeling (green) of retinal sections show that following LPS injection, microglia exhibit a dose-dependent increase in cell density and Iba-1 immunopositivity, as well as an increase in the number of vertically oriented processes (arrowheads) as compared to PBS-injected controls. (B) F4/80 immunolabeling (red), a marker of microglial activation, demonstrates a dose-dependent increase in the density of immunoreactive microglial cells following LPS injection. (C) GFAP immunolabeling (red) located only in astrocytic processes (arrow) in the PBS-injected control, did not change in its localization following LPS injection, indicating that typical Müller cell gliosis, exemplified by increased GFAP expression, did not occur under these conditions. Vimentin (D) and glutamine synthetase (GS) (E) immunolabeling (red), located in Müller cell process, was present under all conditions and were not noticeably different in intensity. No marked changes in the morphology of Müller cells were noted. Scale bar = 50 μM.