Fig. 3

N44Q mutant involved in CD200-CD200R1 interaction and LPS-induced classical microglial activation. We established neuronal-microglia co-cultures to explore the effect of N44Q mutant. a, b LPS significantly increased iNOS mRNA and CD86 mRNA in BV2 cells. The addition of neurons attenuated LPS-induced classical microglial activation. Notably, the present of anti-CD200 antibody blocked the modulating effect of neurons. BV2 cells transfected with N44Q mutant exerted similar effects like anti-CD200 antibody (^*p < 0.01; ⁺p < 0.01; ^#p < 0.01, WT + LPS + neurons vs WT + LPS; ^**p < 0.01; N44Q + LPS + neurons vs N44Q + LPS; ⁺⁺p < 0.01, N44Q + LPS + neurons + anti-CD200 antibody vs N44Q + LPS + neurons; ANOVA; n = 5). c, d IL-1β mRNA and TNF-α mRNA were examined. The LPS-induced effects were reversed in the presence of neurons. Importantly, the addition of anti-CD200 antibody abrogated the modulating effect of neurons, consistent with the cells transfected with N44Q mutant (^*p < 0.01; ⁺p < 0.01; ^#p < 0.05, WT + LPS + neurons vs WT + LPS; ^**p < 0.01; N44Q + LPS + neurons vs N44Q + LPS; ⁺⁺p < 0.01, N44Q + LPS + neurons + anti-CD200 antibody vs N44Q + LPS + neurons; ANOVA; n = 5). Similar results were obtained by ELISA (^*p < 0.01; ⁺p < 0.01; ^#p < 0.01, WT + LPS + neurons vs WT + LPS; ^**p < 0.01; N44Q + LPS + neurons vs N44Q + LPS; ⁺⁺p < 0.01, N44Q + LPS + neurons + anti-CD200 antibody vs N44Q + LPS + neurons; ANOVA; n = 5). Error bars indicate ± SEM