Enhanced neurotoxic potential of PGRN-deficient macrophages and microglia, and increased vulnerability of PGRN-deficient neurons to stress. (A) BMDM-induced cell death in cultured hippocampal slices. WT coronal hippocampal slices were incubated with WT (n = 29) or PGRN-deficient (KO; n = 36) BMDMs with (LPS/IFN-γ) or without (Non) LPS and IFN-γ for 5 d. Cell death was assessed with PI staining. (top) Representative images. (bottom) Quantitative evaluation is expressed as the percentage of PI staining relative to maximal PI staining (Max) induced with 0.1% Triton X-100. The results are means ± SEM from five independent experiments. *, P < 0.001 using the Student’s t test. Bar, 1 mm. (B) Activated microglia-induced cell death in hippocampal slices. Slices (n = 12 per group) from WT or PGRN-deficient mice were incubated with 10 ng/ml GM-CSF (3 d), followed by stimulation with LPS and IFN-γ in the presence of 10 µg/ml anti–IL-10 or control IgG for 3 d. Cell death was measured as in A. The results are means ± SEM from three independent experiments. *, P < 0.002 using the Student’s t test. (C) Effect of OGD on hippocampal slices from PGRN-deficient (KO) and WT mice (n = 6). Slices were cultured for 2 wk, followed by OGD treatment. Neuronal viability was assessed by PI staining before and after OGD. Maximal neuronal death was induced by exposure to 1 mM NMDA after OGD treatment. The results are means ± SEM from three independent experiments. *, P < 0.001 using the Student’s t test.