Figure 4.

Pc Controls Lm Infection by Modifying Mucus Layer and Promoting Inflammation

(A and B) Assessment of listerial CFUs in the intestinal luminal content (A) and in the spleen (B) of germfree (GF) C57BL/6J mice colonized or not with Pc, Ps or Bt or stably colonized with 12 bacterial species (Oligo-MM¹²) for 2 weeks and then inoculated with Lm WT or Δlmo2776 for 72 h.

(C) Numbers of Pc CFUs in the intestinal luminal content of GF C57BL/6J mice colonized with Pc and then inoculated with Lm WT or Δlmo2776 for 72 h.

(D) Confocal microscopy analysis of microbiota localization in colon of BALB/c mice infected with Lm WT or Δlmo2776 bacteria for 24 or 48 h. Muc2 (green), actin (purple), bacteria (red), and DNA (blue). Bar = 20 μm. White arrows highlight the 3 closest bacteria. Pictures are representatives of 5 biological replicates.

(E) Distances of closest bacteria to colonic intestinal epithelial cells per condition over 5 high-powered fields per mouse, with each dot representing a measurement.

(F) Confocal microscopy analysis of microbiota localization in colon of GF C57BL/6J mice colonized with Pc, Bt or Ps for 2 weeks and inoculated with Lm WT or Δlmo2776 bacteria. Muc2 (green), actin (purple), bacteria (red), and DNA (blue). Bar: 20 μm.

(G) Distances of closest bacteria to intestinal cells per condition over 5 high-powered fields per mouse, with each dot representing a measurement.

(H) Levels of the inflammatory marker Lcn-2 in feces of mice 2 weeks pi with Pc or Bt.

(I) Model depicting the effect of Prevotella on Lm infection. In (A), (B), and (E), each dot represents one mouse. Statistically significant differences were evaluated by the Mann–Whitney test (A, B), one way-ANOVA test (E, G) or two-tailed unpaired Student’s t test (C, H) (^∗p < 0.05, ^∗∗∗p < 0.005).