Figure 6: Degenerating neuron-derived DNA activates TLR9 signalling.

(a) Experimental scheme for the identification of an endogenous ligand for TLR9 expressed in microglia. (b) qRT-PCR analyses of Tnf-α levels in microglia from WT and TLR9 KO mice 12 h after incubation with CM from KA-treated or -untreated neurons. TLR9 KO microglia failed to induce Tnf-α expression in response to CM from KA-treated neurons (n=4 experiments). (c) qRT-PCR analyses of Tnf-α expression levels in microglia from WT mice 12 h after incubation with DNase-pretreated CM from KA-treated neurons (n=5 experiments). NS means not significant (P>0.05). *P<0.05 and **P<0.01 by ANOVA with Tukey post-hoc tests.