Fig. 1

Resident Macrophages Are First Responders to Bacterial Infection

(A) Cartoon of a 2 day post-fertilization (dpf) zebrafish showing the caudal vein (CV) and hindbrain ventricle (HBV) injection sites and representative image of HBV (outlined with white dashed line) with Hoechst dye negative resident macrophages (black arrowheads) and Hoechst dye positive monocyte (black arrow). Scale bar, 100 μm.

(B) Mean resident macrophage (RM) and monocyte (Mono) recruitment at 3 hr post infection (hpi) into the HBV after infection with 80 wild-type Mm (Mm) or PGL-deficient Mm (Mm-PGL−). Significance testing done using one-way ANOVA, with Bonferroni’s post-test against mock injections. ^∗∗p < 0.01.

(C) Mean resident macrophage and monocyte recruitment at 3 hpi into the HBV of wild-type or Ccr2-deficient fish after infection with 80 wild-type Mm. Significance testing done using one-way ANOVA, with Bonferroni’s post-test for comparisons shown. ^∗∗p < 0.01.

(D) Representative images of uninfected resident macrophages (black arrowheads), uninfected monocytes (black arrows), infected resident macrophages (red arrowheads), infected monocytes (red arrows), and extracellular bacteria (white arrow) following infection of wild-type fish in the HBV with 80 wild-type green fluorescent Mm at 30, 60, and 120 min post infection (mpi). Scale bar, 20μm.

(E) Mean resident macrophage and monocyte recruitment from 5 to 150 mpi in the HBV of wild-type or Ccr2-deficient fish after infection with 80 wild-type Mm.

(F) Mean resident macrophage and monocyte recruitment from 5 to 180 mpi in the HBV of wild-type or Myd88-deficient fish after infection with 80 PDIM-deficient Mm (Mm – PDIM−).

(G and H) Mean resident macrophage, monocyte, and neutrophil (Neut) recruitment from 5 to 180 mpi in the HBV of wild-type or Myd88-deficient fish following infection with 138 S. aureus (G) or 156 P. aeruginosa (H).

(I) Mean resident macrophage and monocyte recruitment from 5 to 150mpi in the HBV of wild-type fish after injection with 80 wild-type Mm, 300 sterile beads, or mock injection.

(J) Mean resident macrophage and monocyte recruitment from 5 to 150 mpi in the HBV of wild-type fish after infection with 80 wild-type Mm, an equivalent volume of wild-type Mm supernatant (Sup), or media mock.

(K and L) Mean resident macrophage, monocyte, and neutrophil recruitment from 5 to 180 mpi in the HBV of wild-type fish after infection with S. aureus supernatant (K) or P. aeruginosa supernatant (L). (A – L) Results representative of at least three independent experiments.