Figure 6 from Gut Microbiome Profiling in Eμ-TCL1 Mice Reveals Intestinal Changes and a Dysbiotic Signature Specific to Chronic Lymphocytic Leukemia

Antibiotic-mediated microflora ablation delays CLL development, fostering a similar dysbiotic microbiome. A, WT B6 mice were randomly assigned to either receive an antibiotic cocktail (Abx) or normal drinking water (water). Five days before CLL engraftment, mice receiving antibiotics were gavaged with a high-dose Abx. In parallel, mice in the antibiotic arm received antibiotics in drinking water until study end (left). Control mice were gavaged with similar volumes of water and received normal drinking water until study end (left). Following the initial 5-day oral gavage, a baseline fecal pellet sample was obtained, and CLL was initiated via adoptive transfer of Eμ-TCL1 spleen-derived lymphocytes (right; CLL engraftment). Study arm mice were housed in separate cages and monitored over 7 weeks with serial sampling of blood to monitor CLL burden and fecal pellet sample collection for microbiome profiling (n = 10 mice/cohort). Spleens were harvest at 9 weeks after engraftment for further immunophenotyping. B, CLL disease burden was measured by the percentage of CD45⁺/CD19⁺/CD5⁺ cells in the peripheral blood via flow cytometric analysis beginning at 1 week after engraftment (n = 10 mice/cohort). Asterisks denote the significance between antibiotic-receiving or water-receiving mice over time (*, P < 0.05). Hashtags denote the significance between antibiotic-receiving and water-receiving mice at each time point (#, P < 0.05; ##, P < 0.01). Two-way ANOVA with Dunnett multiple comparisons was applied for testing. C–F, Abundances of cell types found in the blood of antibiotic-receiving and water-receiving mice: non-malignant B cells (CD45⁺/CD19⁺/CD5⁻; C) T cells (CD45⁺/CD3⁺; D) monocytic-like MDSCs (M-MDSCs; CD45⁺/B220⁻/CD3⁻/CD11b⁺/Ly6C⁺/Ly6G⁻; E), and granulocytic-like MDSCs (G-MDSCs; CD45⁺/B220−/CD3⁻/CD11b⁺/Ly6Clo/Ly6G⁺; F). Asterisks denote the significance between antibiotic-receiving and water-receiving mice over time (*, P < 0.05). Unpaired Welch t test was applied for testing. G, PCoA plot depicting Bray–Curtis distance as a measure of beta diversity between Abx (blue) and water (red) arms. H, Alpha diversity measured by the Shannon index in antibiotic and water cohorts at time of engraftment and 1, 3, 5, and 7 weeks after engraftment. Data are presented as box-and-whisker plots, with box edges representing the 25th and 75th percentiles, the center line showing the median value, and whiskers extending to minimum and maximum values. Asterisks denote the significance between antibiotic-receiving and water-receiving mice at each time point (***, P < 0.001). Unpaired Welch t test was applied for testing. I, Relative abundance bar plots of bacterial taxa present at the phylum level in the gut microbiome of antibiotic-receiving leukemic mice and water-receiving leukemic mice. Remainder includes all remaining taxa present in the microbiome at decreased abundance. Engraft., engraftment; MDSCs, myeloid-derived suppressor cells; post-eng., after engraftment.