Figure 2

IL-1α is expressed by microglia localized to focal neuronal and BBB injury 24 h after MCAo. Images are coronal sections from brains of C57BL6/H and CX3CR1-GFP +/- mice 60 min MCAo and 24 h reperfusion. Widefield images show IL-1α-expressing (red), GFP positive (green) microglia in ipsilateral (Ai), not contralateral (ii) amygdala 24 h after MCAo in a CX3CR1-GFP +/- mouse. IL-1α immunohistochemistry with cresyl violet co-staining localises IL-1α expressing microglia to the peri-infarct zone in thalamus (Bi) and cortex (Bii) of a C57BL6/H mouse. Focal IgG staining (red) co-localized with IL-1α positive microglia (green) in the ipsilateral cortex of a C57BL6/H mouse (Ci). No IgG or IL-1α staining detected in the contralateral cortex (Cii). IL-1α positive microglia detected in larger areas of IgG staining in the ipsilateral (Ciii), but not contralateral (Civ) hemisphere. Co-localization of IL-1α positive microglia (red) with areas of neuronal loss (blue) in a C57BL6/H mouse (D). Occasional IL-1α positive microglia also found in areas where neurons were morphologically intact (D, inset). Confocal images (E) are maximum Z projections (Ei, iii) and confocal slices at the level of the nucleus (Eii, iv) of IL-1α expressing, GFP positive microglia in a CX3CR1-GFP +/- mouse. Cells with (Ei, ii), and without (Eiii, iv) nuclear IL-1α. Nuclear fluorescence intensities for IL-1α and GFP were quantified from confocal images, and the fold enrichment of IL-1α and GFP in microglial nuclei was calculated in comparison to whole cell fluorescence (F). All images are representative of n ≥ 3 mice. Quantification is of n = 4 CX3CR1-GFP +/- mouse brains, with each data point representing an individual cell, n ≥ 30 cells per brain.