Fig. 6. BLP prevents Lm from causing intestinal barrier loss by maintaining mucus-producing goblet cells and limiting epithelial apoptotic and proliferative cells.

a, b Representative H&E-stained micrographs (bars, 25 µm) (a) and the histological score (b, each point represents an individual mouse) of ileal tissue sections from control (mock-treated) uninfected naive mice or L. casei-treated (10 days, LbcWT or BLP) pre- or post-Lm challenge at 48 hpi (n = 9, 7, 7, 9, 9, 9, 10, 11 mice for each group, respectively). Arrows point to the loss of villous epithelial cells and increased polymorphonuclear and mononuclear cells infiltrating the base of the villous lamina propria in naive (naive + Lm) and LbcWT-treated mice (LbcWT + Lm) at 48 hpi. c–h Representative immunohistochemical micrographs of the ileum stained for Muc2 (c, brown), Ki67 (f, brown) and cleaved caspase-3 (h, brown), nuclei (blue) from control (mock-treated) uninfected naive mice or L. casei-treated (10 days, LbcWT or BLP) pre or post-Lm challenge at 48 hpi. Bars, 10 µm. Quantification of Muc2 (d), Ki67 (e), and CC3 (g)-positive cells, each point represents an individual mouse, four mice per group, n = 100 villi. Arrows point to increased numbers of Muc2 (c) in BLP-treated mice (pre- or post-Lm challenge), and increased numbers of Ki67 (f) and CC3-positive cells (h) in naive or LbcWT-treated mice at 48 hpi. Data in b, d, e, and g represent the mean ± SEM and statistical significance was determined by using the one-way ANOVA test followed by Tukey’s multiple comparisons. For all analyses, ****P < 0.0001; ***P < 0.001; **P < 0.01; *P < 0.05; ns no significance. Source data are provided as a Source Data file.