Fig. 4

Ex vivo LPS-induced inflammation of brain immune cells shows increased CD45 expression within LiveTmem119⁺ cells. The post-Percoll brain cells from the same naïve young brain hemispheres were incubated with or without LPS at 37C for 3 h prior to staining and flow cytometric analysis (a). Examination of Live Tmem119⁺ cells from naïve young brain shows that ex vivo LPS-induced inflammation leads to a significant upregulation of CD45 expression (b). To determine whether stroke will reduce the ability of brain immune cells to upregulate their CD45 expression without any peripheral contribution of the infiltrating immune cells, ex vivo LPS-induced inflammation studies were carried out using contralateral hemispheres of sham and MCAO brains (c–l). No significant population of CD11b⁺CD45^high cells was present in the young sham brain without LPS treatment (d), but a significant population of CD11b⁺CD45^high is found in the young sham contralateral brain with LPS treatment (e). Results show a significant increase in CD11b⁺CD45^high population when comparing LPS-treated post-Percoll brain cells with untreated cells from the same contralateral hemisphere of stroke brains (“Contra-MCAO”, f, g). The analysis shows a significant upregulation of CD45 expression with LPS stimulation in both sham and MCAO assays (j). (n = 4/gp, a one-way ANOVA with Sidak’s multiple comparisons test, *p < 0.05, **p < 0.01, ***p < 0.001)