Figure 4.

Neuroprotection of microglial Siglec-11 in microglia–neuron cocultures dependent on PSA on neurons. A, Microglial cells were lentivirally transduced with the Siglec-11 (Siglec-11) or control vector (Control). PSA was removed from neurons and/or microglia by EndoN treatment. Cells were washed and cocultured for 48 h. Cells were fixed and double-immunostained with antibodies directed against β-tubulin-III (green signal) and Iba-1 (red signal). Confocal images were obtained by laser scanning microscopy. Neurite density was higher in cocultures with Siglec-11-expressing microglia and neurons having PSA residues on their glycoproteins. Scale bars, 50 μm. B, Statistics analysis of neurite density. The number of neurites was determined and values were normalized to those of cocultures with control vector transduced microglia. Data are shown as mean ± SEM; number of independent experiments n = 5, *p < 0.05, ANOVA followed by Bonferroni multiple-comparison test. C, Statistics analysis of neuronal cell body survival. The number of survived neuronal cell body in each treatment was counted and values were normalized to those of cocultures with control vector transduced microglia. Data are shown as mean ± SEM; number of independent experiments n = 5, *p < 0.05, ANOVA followed by Bonferroni multiple-comparison test.