Fig. 1: In vivo and in vitro evidence demonstrates that astrocytes (in the brain, spinal cord and retina) and Müller glia (in the retina) are capable of engulfing microglial debris.

a Scheme of the in vivo astrocytic engulfment examination by ALDH1L1-CreER::Ai14-based astrocyte labeling and microglial depletion. Because ALDL1L1-CreER::Ai14 does not target retinal astrocytes, retinal astrocytes are visualized by GFAP in C57BL/6 J mice treated with CD or PLX5622 for 2 days. b, c Confocal orthogonal colocalization (b) and 3D reconstruction (c) show that tdTomato⁺ astrocytes (in the brain, spinal cord and retina) or Müller glia (in the retina) do not engulf IBA1⁺ microglial debris under physiological conditions (D17) whereas they engulf IBA1⁺ microglial debris upon the CSF1R inhibition (D19). d Quantification of microglial debris engulfment by astrocytes (in the brain, spinal cord and retina) and Müller glia (in the retina). N = 6 mice at D17, 5 mice at D19. Two-tailed independent t test. e Scheme of the in vitro astrocytic engulfment assay using pHrodo-labeled microglial debris. f GFAP⁺ astrocytes engulf pHrodo-labeled microglial debris in FBS-containing culture medium. pHrodo is illustrated by the green pseudocolor for better visualization. g Quantification of astrocytic engulfment after exposure to pHrodo-labeled microglial debris for 0, 24, 48, and 72 h. N = 5 independent biological replicates for each group. One-way ANOVA with Holm‒Sidak’s multiple comparisons test (post hoc). PLX5622: PLX5622-formulated AIN-76A diet; CD: control AIN-76A diet; PLX: PLX5622; MFI mean fluorescence intensity. Data are presented as mean ± SD. The source data are provided as a Source Data file.