Fig. 1: Bacteroides fragilis increases plaque burden and expression of amyloid processing genes in cortex.

APP/PS1 mice were treated with Bacteroides fragilis (Bf) between 2.6–5.0 months of age. A Amyloid plaque burden was assessed by immunohistofluorescence of the cortex. The graph represents the fold change (FC) of plaques in mice treated with Bf vs. controls treated with PBS. Plaque burden is defined as the percent of the cortex area that were covered with plaques and the number of plaques per square millimeter in the cortex. The data is pooled from two independent experiments, PBS: n = 6 mice/group, Bf: n = 7. Three mice from cohort 2 belonging to the PBS group was excluded from the analysis because the tissue was damaged during cutting. Histologic findings from cohort 1 are a modified representation of data originally published in Cox et al., Scientific reports, 2019, under the Creative Commons CC BY license https://www.nature.com/articles/s41598-019-54187-x#rightslink. The p-values were calculated with a two-sided Student’s t test. B–D The cortical tissue from cohort 1 was analyzed for transcriptional changes with the NanoString Neuropathology panel, the statistical test was two-sided. B Volcano plot of differentially expressed genes between APP/PS1 mice treated with Bf or PBS. C Pathways identified by Ingenuity Pathway Analysis (IPA) in APP/PS1 mice treated with Bf vs. PBS, genes with FC > ±0.2 and a p-value < 0.05 were included in the analysis. D Schematic figure of the amyloid processing pathway (adaption of IPA-generated graph) and graphs showing the differentially expressed genes in the pathway, the p-values were generated with NSolver Advanced Analysis. n = 3 mice/group. Violin plots represent min, max, interquartile range and median, the dots represent mice. Source data are provided as a Source Data file.