Fig. 4

Microglia engulf inhibitory synaptic elements in hippocampal subfields of cognitively impaired MS patients. (a) 3D rendering of a Iba1⁺ microglia cell (in grey) engulfing vGat⁺ (in green) and vGlut1⁺ (in red) synaptic vesicles. Graph bars represent the percentage of (b) vGlut and (c) vGat synaptic partners engulfed by Iba1⁺ cells (N = 8 for NDC, MSCP and MSCI). (d) Representative immunohistochemical staining of microglia (Iba1, in green), the complement protein (C1q, in red) and the synaptic partner (vGat, in white), and staining for cell nuclei (DAPI, blue) in the CA1-CA3 regions of hippocampal slices of non-demented donors (NDC) and multiple sclerosis donors diagnosed with preserved (MSCP) and impaired cognition (MSCI). Graph bars represent the percentage of area stained for (e) C1q in Iba1⁺ cells, and the percentage of colocalization between the synaptic partners, (f) vGlut and (g) vGat, with C1q in Iba1⁺ cells. All Iba1⁺ cells were delineated and considered ROIs in the high synaptic regions. The analyses were performed in three different z-stacks followed by the sum of three measurements in each image. Graph bars represent the average of seven images for each donor (N = 8 for NDC, MSCP and MSCI). *p < 0.05 vs. NDC; #p < 0.05 vs. MSCP