Figure 6

TLR2, but not the microbiome, determines macrophage load of MAC 101 from the gut in zebrafish larvae. (A) Schematic of the experimental workflow. (B) Representative fluorescence images showing macrophages containing MAC 101 bacteria in different body regions (representative images are tlr2 wild-type larvae under germ-free (GF) condition). Bacteria are shown in magenta. Macrophages are shown in cyan. Scale bar: 100 µm for full-body images; 25 µm for zooms. The bottom graphs illustrate the spatial colocalization patterns of representative macrophages and bacteria. (C-E) Quantification of the number of bacteria-containing macrophages in the full body (C), anterior region (D), and posterior region (E). Wild-type larvae had significantly more infected macrophages than tlr2 mutants under both GF and CONVD conditions in all regions. No significant differences were observed between GF and CONVD groups within the same genotype. Macrophages containing bacteria were manually counted across the full z-stack for each region. Each z-slice was examined to verify that individual bacteria-containing macrophages were counted once and only once. The data from GF tlr2^+/+ (n=38) group, GF tlr2^-/- (n=34) group, CONVD tlr2^+/+ (n=43) group and CONVD tlr2^-/- (n=37) group are based on three independent experiments. Statistical significant difference was determined by one-way ANOVA, red arrows point to the median, ns, non-significant, *, P <0.05, **, P < 0.01, ***, P < 0.001, ****, P < 0.0001.