Figure 4.

Transient Intestinal Microbial Conditioning Enhances Clearance of Bacteria and Their Metabolites from the Intestine of C57BL/6 Mice Compared with Antibody-Deficient Igh-J^−/− Mice

Germ-free C57BL/6 mice (red) or antibody-deficient Igh-J^−/− mice (blue) were preconditioned with HA107 or control treated. Twelve days after all groups had returned to germ-free status, they were gavaged with ¹³C-labeled HA107 or PBS as control (n = 3–4 per group) and Log₂ fold-changes were calculated (Figure S1Aii).

(A) Samples from small intestinal, cecal, and colon fluids were collected at 2 hr and analyzed with Q-TOF mass spectrometry. Differences between the Log₂-fold values of preconditioned and unconditioned mice are shown for ions annotated as metabolite isotopes with ≥75% ¹³C labeled. Fold-changes based on low abundant ions (counts < 200) were excluded. Mann-Whitney U test; ^∗∗∗p < 0.001.

(B) As for (A), but the plot shows individual compound classes.

(C) Small intestinal transit of replication-deficient bacteria in wild-type mice and antibody-deficient mice. HA107 preconditioned C57BL/6 mice (red symbols) were compared with HA107 preconditioned antibody-deficient Igh-J^−/− mice (blue) 2 hr after challenging with 10⁷ colony forming units (CFU) HA107 delivered into the stomach. The small intestine was divided into 10 sections and CFU in luminal contents of each section were determined with auxtrophic supplements ($\overline{x}$ ± SD n = 3, ^∗p < 0.05).

(D) Whole intestinal transit of replication-deficient bacteria in wild-type mice and antibody-deficient mice. HA107 preconditioned C57BL/6 mice (red symbols) or antibody-deficient Igh-J^−/− mice (blue) were gavaged with 10⁸ CFU HA107. Feces were plated with auxotrophic supplements (^∗p < 0.05). Results are representative of two experiments with ≥6 mice/group.

See also Figure S4.