Fig. 4: Exogenous medin aggregates induce premature amyloid-β aggregation in vivo.
From: Medin co-aggregates with vascular amyloid-β in Alzheimer’s disease
a, Experimental design to assess premature induction (seeding) of amyloid-β aggregation by medin aggregates in vivo. b, Top left, human aorta section from patient 1 (P1) stained for medin and amyloid (Methoxy-X04; note that collagen fibres are autofluorescent), showing a prominent medin deposit (yellow arrowhead). Bottom left, immuno-electron microscopy of human aorta extract. Right, western blotting of aorta extracts and recombinant human medin (rhMedin) using an anti-human medin antibody (6B3). c, Analysis of cerebral β-amyloidosis six months after intrahippocampal injection. Representative images of amyloid-β deposition induced by APP23 mouse brain extract (positive control) and aorta extracts from patients 1 and 2, compared with an age-matched un-injected APP23 mouse, which shows no endogenous deposits. Right, stereological quantification of amyloid-β deposition (APP23 mouse brain extract: n = 3; patient 1 extract: n = 4; patient 2 extract: n = 6 mice). d, Patient 1 aorta extract was diluted 1:10 (for technical reasons) and medin was immunodepleted using anti-human medin 1H4 antibody in four rounds of incubation. Depletion was examined by western blotting with 6B3 antibody. e, Quantification of amyloid-β seeding (extract: n = 6; depleted extract: n = 5 mice). f, Left, aged mouse aorta stained for MFG-E8 (medin) and amyloid (Methoxy-X04, mostly showing autofluorescence). Right, western blotting for MFG-E8 in aged Mfge8 wild-type and Mfge8 C2 KO aortas. g, Quantification of amyloid-β seeding with mouse aorta extracts (Mfge8 wild-type aorta homogenate: n = 7 mice; Mfge8 C2 KO aorta homogenate: n = 7 mice). Data are mean ± s.e.m. c, One-sample t-test against 0. e,g, Two-tailed Mann–Whitney U-test. Scale bars, 25 µm (b, top, h), 100 nm (b, bottom); 250 µm in (c,f,i). Uncropped western blots are shown in Supplementary Fig. 3.
