Fig 2: ECP reprograms AMs to antagonize TGF-ß bioavailability.POD16 2T-FVB and 3T-FVB allograft (A) BALF and plasma analyzed for TGF-ß isoform protein content by ELISA (n = 6/group) or (B) activity with a HEK293 SMAD 2/3 luciferase reporter cell line (n = 5/group). AU, arbitrary luciferase units. Data shown for A and B are representative results from 2 experiments. (C) CellTrace633-labeled ECP-treated leukocytes injected into 3T-FVB allograft and analyzed for uptake by intragraft CD11b+ phagocytes. Data shown are representative results from 4 experiments. (D) Heatmap of saline- and ECP-treated POD16 3T-FVB allografts, AM transcript levels of TGF-ß signaling, and fibrosis-related gene targets normalized to the macrophage housekeeping gene Stx5a. (n = 4/group) (E) Fold accumulation of TGF-ß–induced AM Serpine1 mRNA accumulation in the presence or absence of 10 µM SB43152 or vehicle (DMSO) (n = 4/group). Data shown are normalized to baseline levels (non–TGF-ß–treated DMSO-pretreated controls). (F) Saline- and ECP-treated AMs were cultured overnight and analyzed by ELISA for DCN secretion (n = 7/group). (G) TGF-ß activity measurements of enriched supernatants from saline- or ECP-treated DCN?/? and DCNfl/fl AMs cultured with or without 10 ng/ml TGF-ß1 (n = 5/group). Data shown in F and G are representative results from 2 experiments. (H) Naive B6 CD4+ T cells were stimulated with plate-bound CD3e and CD28 Abs in the presence or absence of indicated AM-conditioned supernatants added at a 1:1 v/v ratio to Th17 polarization medium that contained 10 ng/ml TGF-ß1 (n = 5/group). Intracellular IL-17A expression was assessed 4 days later. Data are represented as mean ± SD. One-way ANOVA with Dunnett’s multiple-comparison test (A, B, G, and H); 2-sided Mann-Whitney U test (D and F). *P < 0.05; **P < 0.01; ***P < 0.001.

Fig 3: Increased CSF-decorin in three different mouse models of Aß pathology. a, b Immunostaining and quantification of decorin in the ChP. Scale bars, 100 µm. (n = 4). c Double immunostaining of DCN and PV or d SRIF in mouse hippocampus. e Quantification of decorin-positive cell-type distribution. Scale bars, 500 µm. (n = 3). f, g Immunostaining and quantification of decorin in the hippocampus. Scale bars, 500 µm. (n = 4). h Mouse CSF-decorin levels in three months old (n = 5), i 13 months old (n = 4–5), j 18 months old (n = 3–5) mice were measured by ELISA and quantified. k CSF-decorin levels in AppNL-F/NL-F mice of different ages were measured and quantified. (n = 3–5). l Decorin levels in Aß42 treated mouse primary neurons and (m) were quantified (n = 4). n Quantification of decorin levels in conditioned media. (n = 8). Data in (b, g–k) were analyzed by one-way ANOVA followed by Dunnett’s multiple comparisons test. Data in (m, n) were analyzed by student’s t-test. Data in (e) were analyzed by two-way ANOVA followed by Tukey’s post hoc test. Data are represented as mean ± SEM; *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. DCN decorin, PV parvalbumin, SRIF somatotropin release-inhibiting factor, PN pyramidal neurons, ns not significant

Fig 4: CSF-decorin positively correlates with CSF-Aß42 in a + t- preclinical AD and predicts a subtype of AD. a CSF-DCN levels in a-t- healthy (n = 82) and a + t- subjects with preclinical AD (n = 36), MCI (n = 24), AD (n = 17), and a + t + AD (n = 62). (*p < 0.05 as compared to a-t- healthy). b Correlations of CSF-DCN and CSF-Aß42, c CSF-DCN and CSF-t-tau, d CSF-DCN and CSF-p-tau in a-t- healthy and a + t- preclinical AD subjects. The regression coefficients (Beta) and p-values are displayed. (*p < 0.05, **p < 0.01, ****p < 0.0001). e Hypothetical curve showing CSF-DCN alteration from a-t- healthy subjects to a + t- preclinical AD, MCI, AD and a + t + AD subjects and its correlation with CSF-Aß42 and CSF-tau levels. f Receiver operating characteristic (ROC) analysis was performed in a + t- preclinical AD (n = 36) versus healthy control (n = 82) and revealed an area under the ROC Curve (AUC) (95% confidence interval (CI)) = 0.61 (0.50, 0.73) (p = 0.058) for CSF-DCN levels. g ROC curve was performed in a subtype classified by as innate immune activation (n = 71) versus healthy control (n = 82) and revealed an AUC (95% CI) = 0.70 (0.62, 0.79) (p = 1.73 × 10–6) for CSF-DCN levels. Data in (a) were analyzed by one-way ANOVA followed by Tukey’s multiple comparisons test. Data are represented as mean ± SEM. DCN: decorin

Fig 5: DCN and VCAN exhibit stratified localization in the Adamts5-/- PV at P7 that display a transient phenotypic rescue and similar to WT. DCN localization (green) at postnatal day 0 (P0; B,D,E) and P7 (H,I,K,L) and VCAN (blue) at P0 (C,F) and P7 (G,J). c—valve cusp; h—valve hinge region. Yellow asterisks (B,C,G,H,J,K) indicate complementary expression patterns of DCN and VCAN while yellow lines (E,F) designate overlapping expression patterns of DCN and VCAN. Red-propidium iodide. Bar in (A) = 150 µm and applies to (D); Bar in (B) = 50 µm and applies to (C,E,F,I,L); Bar in G = 225 µm and applies to (H,J,K).