Fig. 4: Raffinose underlies diet-dependent epithelial response to stress.

a Heatmap showing the different abundance of oligosaccharides and polyphenolic compounds in chow diet (CD) and purified diet (PD). b Comparison of the Log2-fold changed abundance of oligosaccharides and polyphenolic acid components between CD and PD. Points in red and green represent components enriched in CD and PD, respectively. c Schematic of the experimental design to assess the role of dietary raffinose. Mice were fed with PD or PD supplemented with raffinose (RD, 100 g/kg diet) during 14 days of restraint stress (n = 10), and a cohort of mice was subsequently exposed to 2% (wt/vol) DSS for 7 days. d Representative Olfm4 staining images and quantification of Olfm4-positive cells per crypts in the ileum of mice after 14 days RS. Scale bar: 100 µm. Data are represented as mean ± SEM for n = 4 biologically independent samples (p = 0.03). e Representative images of organoids derived from the intestinal crypts of stressed mice fed on PD or RD. The  number of organoid per crypt and crypt domain per organoid were compared. Scale bar: 200 µm. Data are represented as mean ± SEM for n = 4 (p = 0.009 for organoid per crypt; p = 0.0006 for crypt domain per organoid). f Linear discriminative analysis (LDA) score obtained from LEfSe analysis of fecal microbiota in PD and RD-fed mice after stress. A genus with Kruskal–Wallis ≤ 0.05, as well as LDA > 4, are reported. g In vitro growth curve of L. reuteri with or without raffinose supplementation in the culture medium. Data are represented as the average optical density (OD, 600 nm) of culture ± SEM for n = 3. h Colon length of PD and RD-fed mice with DSS-induced colitis. Data are represented as mean ± SEM for n = 4 (p = 0.0002). i Representative H&E staining images and a histologic score of distal colon section of colitis mice. Scale bar: 200 µm. Data are represented as mean ± SEM for n = 4 (p = 0.004). j Relative mRNA expression of Il1β, Il6, and Mcp1 in the colon tissue of colitis mice. Data are represented as average fold change ± SEM for PD-RS/DSS group (n = 4) and RD-RS/DSS group (n = 5). p = 0.01 for Il1β; p = 0.014 for Il6; p = 0.1 for Mcp1.Statistical significance in d, e, h–j was determined by unpaired two-tailed Student’s t-test. ns no significance. *p < 0.05, **p < 0.01, ***p < 0.001.