Fig. 1

Absence of host microbiota reduces hippocampal Aβ depositions of 5xFAD mice. (a) Representative fluorescence images of thiazine red⁺ (TR; red) compact Aβ plaques in the hippocampus of 4 months old SPF, GF and ABX-treated 5xFAD mice. Nuclei were stained with DAPI (blue). Overview of hippocampus and magnification of subiculum (dashed line) are shown. Scale bars represent 300 μm (overview) and 50 μm (insert). (b) Quantification of the number of TR⁺ Aβ-plaques per mm², (c) percentage of TR⁺ area and (d) average TR⁺ plaque size (μm²) in coronal hippocampal sections. Each symbol represents one mouse. Data are presented as mean ± s.e.m. Significant differences were determined by one-way ANOVA followed by Tukey’s post-hoc comparison test (*P < 0.05, **P < 0.01, ***P < 0.001). Data are representative of four independent experiments. Enzyme-linked immunosorbent assay (ELISA) for (e) insoluble Aβ42, (f) insoluble Aβ40, (g) soluble Aβ42 and (h) soluble Aβ40 fractions of hippocampal brain extracts from 4 months old SPF, GF and ABX-treated 5xFAD mice. Each symbol represents one mouse. Data are presented as mean ± s.e.m. Significant differences were determined by one-way ANOVA followed by Tukey’s post-hoc comparison test (**P < 0.01, ***P < 0.001). Data are representative of two independent experiments. (i) Representative immunoblots of hippocampal brain homogenates from 4 months old SPF, GF and ABX-treated 5xFAD mice against human full-length amyloid precursor protein (APP-FL), C-terminal fragment (CTF) α, CTF-β, β-site of APP cleaving enzyme (BACE) 1, A Disintegrin And Metalloproteinase (ADAM10), γ-secretase complex (Nicastrin, presenilin enhancer (PEN) 2, Presenilin (PS) 1, PS2) and Aβ (6E10). β-Actin was used as loading control. Each lane represents one mouse. Quantification of (j) APP-FL, (k), CTF-β, (l) CTF-α, (m) BACE1, (n) ADAM10, (o) PS1, (p) PS2, (q) PEN2, (r) Nicastrin, and (s) Aβ protein levels normalized to β-Actin are shown. Each symbol represents one mouse. Data are presented as mean ± s.e.m. Significant differences were determined by one-way ANOVA followed by Tukey’s post-hoc comparison test (*P < 0.05). Data are representative of two independent experiments. (t) Representative fluorescence images of TR⁺ compact Aβ plaques in the hippocampus of 10 months old 5xFAD mice. Nuclei were stained with DAPI (blue). Overview of hippocampus and magnification of subiculum (dashed line) are shown. Scale bars represent 300 μm (overview) and 50 μm (insert). (u) Quantification of the number of TR⁺ Aβ-plaques per area (mm²), (v) percentage of TR⁺ area and (w) average of TR⁺ plaque size (μm²). Each symbol represents one mouse. Data are presented as mean ± s.e.m. Significant differences were determined by one-way ANOVA followed by Tukey’s post-hoc comparison test (**P < 0.01, ***P < 0.001). Data are representative of four independent experiments