Fig. 1.

CD200R1-KO mice have greater mortality associated with exacerbated microgliosis and monocyte infiltration independent of infarct size at 72 h after ischemic stroke. A Kaplan-Meier survival curve shows the extent of mortality in each group of a cohort following 60 min of MCAO (a; N = 18–21/group). Neurological deficit scores were assessed for each group at 72 h (b; N = 18/group). Representative images of 2,3,5-triphenyltetrazolium chloride (TTC)-stained coronal brain sections for CD200R1-knockout (KO) and CD200R1-wild-type (WT) control littermates at 72 h after 60 min of middle cerebral artery occlusion (MCAO) (c). Infarct volumes were measured for the total ipsilateral hemispheric area relative to the contralateral side (d; N = 9/group). Representative dot plots depict the extent of CD45^intCD11b⁺ microgliosis and CD45^hiCD11b⁺ myeloid cell infiltration in the ischemic brain of each group (e). The absolute number of microglia (CD45^intCD11b⁺Ly6C⁻) was quantified at 72 h (f; N = 7/group). The absolute number total infiltrating myeloid cells (CD45^hiCD11b⁺) and putative lymphocytes (CD45^hiCD11b⁻) was quantified (g). A dot plot shows the identification of specific myeloid subsets in the ischemic brain (h). The number of monocytes (CD45^hiCD11b⁺Ly6C⁺Ly6G⁻) and neutrophils (CD45^hiCD11b⁺Ly6C⁺Ly6G⁺) was compared between genotypes (i). The percentage of CD49d-positive monocytes in the blood and brain of stroke-injured mice is shown (j) by histogram (CD200R1-WT = blue, CD200R1-KO = red, blood = dotted line, brain = solid line, FMO = shaded gray). Quantification of these data shows greater α4-integrin upregulation on circulating monocytes in CD200R1-KO mice (k). Representative histograms illustrate the relative level of CD200R1 expression on CD45^intCD11b⁺ microglia, CD45^hiCD11b⁺ myeloid cells, and CD45^hiCD11b⁻ lymphocytes in the brain at 72 h after stroke (l; KO = red, WT = blue). Quantification of these data is shown (m; N = 7–15/group). Asterisks adjacent to group labels designate an effect of genotype by one-way ANOVA. FMO controls were used to determine positive gating. Error bars show mean SEM. SH sham, ST stroke, KO knockout, WT wild-type, SEM standard error of mean. *p < 0.05; **p < 0.01; ***p < 0.001