Fig 2: VCAM1–ApoE interaction is critical for the Aβ chemotaxis of microglia and microglia-mediated Aβ clearance after IL-33 treatment.a–c, ApoE-neutralizing antibody inhibits the Aβ chemotaxis of microglia upon IL-33 treatment. a, Schematic diagram showing the protocol for ApoE-neutralizing antibody administration before IL-33 treatment in APP/PS1 mice. b,c, Representative images (b) and violin plot (c) showing the distance between chemotactic microglia (that is, Vcam1+ Cx3cr1+ cells) and the nearest Aβ plaque 24 h after administration of ApoE-neutralizing antibody in IL-33-treated APP/PS1 mice (IgG Con: n = 107 microglia from 6 mice; IgG IL-33: n = 115 microglia from 5 mice; αApoE Con: n = 94 microglia from 6 mice; αApoE IL-33: n = 93 microglia from 6 mice; Kruskal–Wallis test with Dunn’s multiple comparisons test). Dotted circle indicates 10 μm from the perimeter of the Aβ plaque. Arrowheads indicate Vcam1-expressing microglia. Scale bar = 10 μm. d–i, VCAM1–ApoE interaction is required for inducing the phagocytic state transition of microglia after the induction of VCAM1 expression. d–f, Representative images (d) and bar plots showing the proportions of Aβ plaque-associated microglia (e) and phagocytic microglia (f) (that is, MHC-II+ Iba1+ cells) 24 h after administration of ApoE-neutralizing antibody in IL-33-treated APP/PS1 mice (IgG Con: n = 5; IgG IL-33: n = 5; αApoE Con: n = 5; αApoE IL-33: n = 5; two-way ANOVA with Šidák’s multiple comparisons test). Arrowheads indicate phagocytic microglia. Scale bar = 20 μm. g–i, Representative images (g) and bar plots showing the proportions of Aβ plaque-associated microglia (h) and phagocytic microglia (i) (that is, MHC-II+ Iba1+ cells) 24 h after IL-33 treatment in APP/PS1-ApoE–knockout mice (n = 6 per condition; two-way ANOVA with Šidák’s multiple comparisons test). Scale bar = 20 μm. j,k, Representative images (j) and bar plot (k) showing the Aβ plaque areas in the cortex 48 h after administration of ApoE-neutralizing antibody in IL-33-treated APP/PS1 mice (IgG Con: n = 5; IgG IL-33: n = 7; αApoE Con: n = 4; αApoE IL-33: n = 4; two-way ANOVA with Šidák’s multiple comparisons test). Scale bar = 200 μm. All data are mean ± s.e.m.Source data

Fig 3: ST2 genetic ablation inhibits the induction of the chemotactic transcriptomic state in microglia after interleukin-33 treatment.a, Bar plot showing the distance between chemotactic microglia (that is, Vcam1+ Cx3cr1+ cells) and the nearest amyloid-beta (Aβ) plaque 3, 8, and 24 h after interleukin-33 (IL-33) treatment (n = 4 mice per condition; one-way ANOVA with Dunnett’s multiple comparisons test). b, Venn diagram showing the overlap between 529 differentially expressed genes (DEGs) (IL-33–treated APP;ST2KO vs. IL-33-treated APP;ST2WT mice) and the signature genes of chemotactic microglia (n = 4 per condition). c, Bar plots showing the expression levels of the representative chemotactic signature genes in the 3 conditions (Wald test from DESeq2). d-f, Genetic ablation of ST2 in microglia inhibits the Aβ chemotaxis of microglia and microglia-mediated Aβ clearance upon IL-33 treatment. d, Schematic diagram showing the protocol for tamoxifen and IL-33 administration in APP/PS1;ST2-icKO mice. e,f, Bar plots showing the proportions of Aβ plaque-associated microglia (e) and Aβ levels in cortical regions (f) after IL-33 treatment in APP/PS1;ST2-icKO mice (wild-type [WT] Con: n = 5; WT IL-33: n = 6; icKO Con: n = 6; icKO IL-33: n = 6; two-way ANOVA with Šidák’s multiple comparisons test). g-i, The induction of VCAM1+ chemotactic microglia is a generalized IL-33 response in microglia. g, Bar plot showing the expression level of Vcam1 in microglia 3 h after IL-33 treatment (WT Con: n = 4; WT IL-33: n = 5; APP/PS1 Con: n = 3; APP/PS1 IL-33: n = 3; two-way ANOVA with Šidák’s multiple comparisons test). h,i, Representative images (h) and quantification (i) showing the proportion of chemotactic microglia (that is, Vcam1+ Cx3cr1+ cells) after interleukin-33 (IL-33) treatment in WT mice (n = 3 mice per condition; two-tailed unpaired Student’s t-test). Arrowheads indicate Vcam1-expressing microglia. Scale bar = 10 μm. All data are mean ± s.e.m. Source data

Fig 4: ST2-dependent induction of chemotactic microglia is required for Aβ clearance upon IL-33 treatment.a,b, Chemotactic microglia migrate toward Aβ plaques after IL-33 treatment. Representative images (a) and violin plot (b) showing the distance between chemotactic microglia (that is, Vcam1+ Cx3cr1+ cells) and the nearest Aβ plaque 3, 8 and 24 h after IL-33 treatment (3 h: n = 83 microglia from four mice; 8 h: n = 92 microglia from four mice; 24 h: n = 89 microglia from four mice; Kruskal–Wallis test with Dunn’s multiple comparisons test). Dotted circle indicates 10 μm from the perimeter of the Aβ plaque. Arrowheads indicate Vcam1-expressing microglia. Scale bar = 10 μm. c,d, Genetic ablation of ST2 inhibits the microglial chemotactic state 3 h after IL-33 treatment. Representative contour plots (c) and bar plot (d) showing the proportions of chemotactic microglia in each group (Con APP/PS1;ST2WT mice: n = 4; IL-33–treated APP/PS1;ST2WT mice: n = 5; Con APP/PS1;ST2KO mice: n = 4; IL-33–treated APP/PS1 mice; ST2KO: n = 5; two-way ANOVA with Šidák’s multiple comparisons test). e–g, Genetic ablation of ST2 inhibits the induction of MHC-II+ phagocytic microglia 24 h after IL-33 treatment. Representative images (e) and bar plots showing the proportions of Aβ plaque-associated microglia (f) and phagocytic microglia (g) in each group (Con APP/PS1;ST2WT mice: n = 9 for panel f and n = 10 for panel g; IL-33-treated APP/PS1;ST2WT mice: n = 10 for panel f and n = 8 for panel g; Con APP/PS1;ST2KO mice: n = 8; IL-33-treated APP/PS1;ST2KO mice: n = 9; two-way ANOVA with Šidák’s multiple comparisons test). Arrowheads indicate phagocytic microglia. Scale bar = 20 μm. h,i, Genetic ablation of ST2 attenuates Aβ clearance induced by IL-33 48 h treatment. Representative images (h) and bar plot (i) showing the Aβ plaque area in the cortex 48 h after IL-33 treatment in each group (Con APP/PS1;ST2WT mice: n = 10; IL-33-treated APP/PS1;ST2WT mice: n = 9; Con APP/PS1;ST2KO mice: n = 9; IL-33–treated APP/PS1;ST2KO mice: n = 7; two-way ANOVA with Šidák’s multiple comparisons test). Scale bar = 200 μm. All data are mean ± s.e.m.Source data

Fig 5: Chemotactic microglia migrate toward amyloid-beta plaques after interleukin-33 treatment.a-c, The induction of chemotactic microglia lasts throughout the chemotactic phase. a,b, Representative images (a) and quantification (b) showing the proportion of chemotactic microglia (that is, Vcam1+ Cx3cr1+ cells) after interleukin-33 (IL-33) treatment (3 h Con: n = 4; 3 h IL-33: n = 5; 8 h Con: n = 3; 8 h IL-33: n = 4; 24 h Con: n = 5; 24 h IL-33: n = 4; two-way ANOVA with Šidák’s multiple comparisons test). Arrowheads indicate Vcam1-expressing microglia. Scale bar = 10 μm. c, UMAP plots showing Vcam1 expression across conditions. d, Bar plot quantifying the proportions of chemotactic microglia (that is, Vcam1+ Cx3cr1+ cells) in uninjected and PBS-injected (Con) APP/PS1 mice (n = 4 mice per condition; two-tailed unpaired Student’s t-test). e, UMAP plots showing H2-Ab1 expression across conditions. f,g, Induction of MHC-II+ phagocytic microglia after IL-33 treatment. Representative contour plots (f) and quantification (g) showing the proportions of MHC-II+ phagocytic microglia (that is, MHC-II+ CD11b+ cells) after IL-33 treatment (Con: n = 3 mice; 3 h: n = 3 mice; 8 h: n = 3 mice; 24 h: n = 4 mice; one-way ANOVA with Dunnett’s multiple comparisons test). h,i, Chemotactic microglia gradually express MHC-II after IL-33 treatment. Representative contour plots (h) and quantification (i) showing the proportions of MHC-II–expressing chemotactic microglia (that is, MHC-II + VCAM1 + CD11b+ cells) after IL-33 treatment (3 h: n = 4 mice; 8 h: n = 4 mice; 24 h: n = 4 mice; one-way ANOVA with Dunnett’s multiple comparisons test). All data are mean ± s.e.m. Source data