Fig 2: Complement inhibitory treatment ameliorates brain blood vessels damage in CAA.Tg-SwDI/B+/+, Tg-SwDI/B+/- and WT mice were treated with complement inhibitory therapy, namely PMX-53 (0.25 mg per mouse, o.p.). Mice were sacrificed at 12w of age. N = 5 in each WT ± PMX-53 groups, N = 4 in Tg-SwDI/B+/- ± PMX-53 groups; N = 3 in Tg-SwDI/B+/+ ± PMX-53 groups. a Major pathophysiological events (left) and time line of complement inhibition therapy (right) were displayed. b Coronal brain sections of mice were collected and subjected to immunostaining of CD31 (green) and ZO-1 (red) to evaluate the tight junction integrity. c Leakage of 3kDa-Dextran in the brain parenchyma was assessed with fluorescent microscopy. d Plasma NeFL concentration as assessed with ELISA. N = 5 mice in each WT ± PMX-53 groups, N = 4 mice in Tg-SwDI/B+/- ± PMX-53 groups; N = 3 mice in Tg-SwDI/B+/+ ± PMX-53 groups. Data are presented as mean values ± SEM with the indicated significance (compared with vehicle treated group (Veh, water) by two-tailed Student’s t test. e Fluorescent intensity of 3kDa-Dextran in the plasma and eyeballs was assessed with a 96-well plate fluorescence reader. N = 5 mice in each WT ± PMX-53 groups, N = 4 mice in Tg-SwDI/B+/- ± PMX-53 groups; N = 3 mice in Tg-SwDI/B+/+ ± PMX-53 groups. Data are presented as mean values ± SEM with the indicated significance (compared with vehicle treated group by two-tailed Student’s t test). f White matter integrity was assessed with MBP/NFH immunostaining. MBP MFI in striatum (STR) and cortex (CTX) was evaluated. Source data are provided as a Source Data file.

Fig 3: Macrophage derived migrasomes are detected in CAA patients and animal models.a Skin autopsy samples of a CAA patient and a brain trauma patient were subjected to TEM. Red stars emphasize blood vessel lumen. Data are representative of 3 biologically independent experiments. b Representative TEM images of plasma migrasomes after negative staining. Data are representative of 3 biologically independent experiments. c, d Quantity of the percentage of CD14+ migrasomes (per 100 µl plasma) were recorded. Plasma samples of 12 CAA patients, 10 AIS patients, 10 CADASIL patients, 28 aCSVD patients, 10 AD patients and 12 healthy controls were analyzed. Data are presented as mean values ± SEM with the indicated significance (by one-way ANOVA followed by Tukey’s post-test). e Upper: Representative tSNE plot of the cellular components in circulating leukocytes. Middle: tSNE analysis of TSPAN4 expression among leukocytes. Fluorescence of CD66b, CD14, CD3 and CD19 was included in the tSNE analysis. Lower: Comparison of TSPAN4 expression among leukocytes. Data are presented as mean values ± SEM with the indicated significance (by two-tailed Student’s t test). N = 12 in CAA group. N = 12 in HC group. f Migrasome markers expression in monocytes (CD14+). N = 12 in CAA group. N = 12 in HC group. Data are presented as mean values ± SEM with the indicated significance (by two-tailed Student’s t test). g Association of CAA biomarker candidates and CAA indications was evaluated with two-tailed Spearman correlation analysis without adjustment. The values represent P values, and the colors represent the values of r. N = 12 in CAA group. N = 12 in HC group. h Graph depicts the results of the ROC analysis for CAA diagnostic efficacy of monocyte TSPAN4 expression, plasma Aß40 level and plasma NeFL concentration. TRUE = CAA, FALSE = HC. N = 12 in CAA group. N = 12 in HC group. i Representative images of TEM with brain tissue of CAA and wild type (WT) mice. Red stars emphasize blood vessel lumen. Data are representative of 3 biologically independent experiments. Scale bar = 1 µm. Source data are provided as a Source Data file.