Figure 6. Subsets of activated microglia/macrophage in EAE hippocampus express IL-1β.

Double immunostaining of hippocampal coronal sections showing expression of IL-1β (green) in Iba1-positive microglia/macrophage cells (red), which was strongly activated in EAE mice (A–C) (20 dpi; score ≥2) but not in CFA mice (D–F). Arrowheads in A show the lesion sites inside the EAE hippocampus. B–C) In the EAE lesion sites marked out by DAPI staining (B) and localized in proximity of the dentate gyrus, CA3 and fimbria, a colocalization between IL-1β (B”) and Iba1 (B’) was evident (merge image in B), indicating a strong expression of the cytokine in these cells. No lesions and colocalization signals were detected in CFA hippocampus (E–F). B and E are high magnifications of the boxes in A (white box) and D (red box), respectively. On the contrary, the activated microglia cells (B’) which were far from the lesion sites did not to express detectable levels of IL-1β (B”). C and F are high magnifications of the white boxes in B and F, respectively. Scale bars in A and D is 200 µm; B–B’–B” and E is 100 µm; in C–C’–C” and F is 50 µm.