Fig. 7

Inflammatory cell accumulation in the mouse IA wall at Day 15 post-aneurysm induction. a Representative image of CD3⁺ cell accumulation around the IA vessel. Scale bar: 100 μm. b Quantification confirmed increased infiltration of CD3⁺ T-cells in the IA area. N = 11 mice, n = 53 IAs/n = 11 contra arteries. ****P < 0.0001, Mann–Whitney U test. c Representative image of Ly6G⁺ cells infiltrating the IA vessel wall. Scale bar: 100 μm. d Quantification confirmed increased infiltration of Ly6G⁺ neutrophils in the IA area. N = 11 mice; n = 51 IAs/n = 11 contra arteries. ****P < 0.0001, Mann–Whitney U test. e, f Infiltrating neutrophils co-localize with MPO and H3Cit positive signal. Scale bar: 50 μm. g Proportion of Ly6G⁺ MPO⁺ cells colocalization in the human MCA IA sample. h Proportion of Ly6G⁺ H3Cit⁺ cells in the human MCA IA sample. i Iba⁺ cell quantification shows increase in the number of microglia around the IA area. ****P < 0.0001. N = 6 mice, n = 29 IAs/n = 11 contra arteries, Mann–Whitney U test. j Microglial activation in the IA area confirmed with the expression of specific microglial activation markers. Scale bar: 100 μm and 10 μm, respectively. CD68 lysosomal marker was used to confirm the active microglia. Unlike the resting form of microglia found around the arteries on the contralateral hemisphere with long branched processes, microglia near the IA site show round shape, with decreased process extension. Closer to the IA, the expression of P2Y12R is found to be decreased, while expression of Iba1 marker is still highly present. k, l Unbiased automatic analysis of microglia morphological confirms the activation in the area of IAs. A significant decrease in the branch volume, branching and ending nodes and the increase in the sphericity was found ipsilaterally, in compared to the contralateral side. (****P < 0.0001, N = 5 mice/group. Kruskal–Wallis test followed by Dunn’s multiple comparisons test). Further detailed information on statistics is provided in the Methods and Materials