Fig. 3: Diet-enriched Lactobacillus strains sustain epithelial renewal in stressed mice.

a Schematic of the experimental design to assess the role of stress-shaped gut microbiota in epithelial injury. Germ-free (GF) mice received fecal microbiota transplant (FMT) derived from control (Con-GF) or restraint-stressed (RS-GF) donor mice fed chow diet. One week after FMT, mice were treated with 2.5% (wt/vol) DSS for 7 days. b Disease activity index (DAI) score and colon length of recipient mice. Data are represented as mean ± SEM for n = 6 (p = 0.04 for DAI; p = 0.02 for colon length). c Representative H&E staining images and a histologic score of distal colon section of mice. Scale bar: 100 µm. Data are represented as mean ± SEM for n = 4 (p = 0.0001). d Linear discriminative analysis (LDA) score obtained from LEfSe analysis of cecum microbiota in Con-GF and RS-GF mice with colitis. A genus with Kruskal–Wallis ≤ 0.05, as well as LDA > 2 is reported. e Average relative abundance of representative Lactobacillus species of chow diet-fed mice with or without stress. Data are represented as average relative abundance ± SEM for n = 4. f Schematic of the experimental design to assess the contribution of Lactobacillus reuteri (L. reuteri) in epithelial response to stress. Mice fed on a purified diet (PD) were colonized with live L. reuteri (2*10⁸ CFU per mouse) or heat-killed controls every day during 14 days of restraint stress. A cohort of mice was subsequently exposed to 2% (wt/vol) DSS for 7 days. g Representative Olfm4 staining images of the ileum (upper panel) and Lgr5 staining images of the colon (lower panel) from stressed mice fed with PD. Quantification was performed for positive cells per crypt. Scale bar: 100 µm. Data are representative of two independent experiments and expressed as mean ± SEM for n = 4 (p = 0.001 for Olfm4 staining; p = 0.0005 for Lgr5 staining). h Representative images of organoids derived from the intestinal crypts of restraint-stressed (RS) mice. Scale bar: 200 µm. Data are represented as Mean ± SEM for n = 5 (p = 0.0024). i DAI score and colon length of colitis mice with prior restraint stress for 14 days. Data are represented as mean ± SEM for n = 8 (p = 0.037 for DAI; p = 0.006 for colon length). j Representative H&E staining images of distal colon section from colitis mice with or without prior L. reuteri treatment. Scale bar: 100 µm. Data are represented as mean ± SEM for n = 4 biologically independent samples (p = 0.0028). Statistical significance was all determined by unpaired two-tailed student’s t-test, *p < 0.05, **p < 0.01, ***p < 0.001.