Figure 4.

Protective effect of microglia activated with each subclass of CpG against oAβ1-42 neurotoxicity. A: Class B and class C, but not class A, CpGs exhibited neuroprotective effects against oAβ1-42 neurotoxicity in neuron-microglia co-cultures. After 3 hours incubation with 100 nmol/L class A, class B, or class C CpGs, oAβ1-42 was added to neuron-microglia co-cultures for 24 hours. Neurons were stained with anti-MAP-2 antibody (green). Aβ was stained with 4G8 (red), and microglia were stained with anti-CD11b antibody (blue). Scale bar, 50 μm. B: Neuronal survival rate was quantified. The viability of neurons in untreated co-cultures (control) was normalized to 100%. ^∗P < 0.05 as compared with the co-cultures treated with oAβ1-42 alone. Each column indicates the mean ± SEM (n = 7). C: Western blot analysis of oAβ1-42 in neuron-microglia co-cultures with subclassese of CpG treatment. Neuron-microglia co-cultures (neu + mi) were treated with 5 μmol/L oAβ1-42 for 24 hours following 3 hours of treatment with 100 nmol/L class A, class B, or class C CpGs. Microglia activated with class B or class C CpGs reduced the amount of oAβ1-42 in the supernatants. D: Semiquantification of oAβ1-42 in C by densitometric analysis. The amount of oAβ1-42 in neuron-microglial co-cultures without CpG (black) was normalized to 100%. oAβ1-42 in co-cultures treated with class A CpG (blue), class B CpG (green), or class C CpG (red) was calculated. ^∗∗P < 0.01 compared with the intensity of oAβ1-42 in neuron-microglia co-cultures without CpG. Each column indicates the mean ± SEM (n = 7). The production of HO-1 (E) and MMP-9 (F) by microglia activated with subclasses of CpG in the absence or presence of oAβ1-42. After 3 hours incubation with 100 nmol/L class A, class B, or class C CpGs, microglial cultures were treated with or without oAβ1-42 for 24 hours. ^∗P < 0.05 as compared with untreated control cultures. Each column indicates the mean ± SEM (n = 3–5).