Fig. 8

IL8-dependent mobilization of neutrophils is crucial for controlling M. abscessus infection and elaborating granulomas.

(A) qRT-PCR of il8 (normalized to ef1α) upon Mabs infection in R Mabs iv infected WT, tnfr morphants or LipoC embryos (≈150 CFU). Fold induction to PBS- injected animals at 3 dpi. Data are mean ± SEM of two independent experiments. (B and C) WT, LipoC embryos (B) or tnfr morphants (C) Tg(mpx:eGFP) embryos were infected into the otic vesicle with ≈150 R Mabs and treated with IL8 injection. Mean number of recruited neutrophils into the otic cavity in response to Mabs/IL8 injection at 3 hpi. Each symbol represents individual embryos and horizontal lines indicate the mean values. (D-F) WT or tnfr morphants were injected into the otic cavity with either ≈150 R or S variants expressing tdTomato and treated with IL8 injection. (D) Survival of R-(up) or S-infected (down) embryos (n = 50–60, two independent experiments). (E-F) Bacterial loads (FPC, two independent experiments, horizontal lines indicate the mean values) (E) and representative confocal images (F) of 3 dpi embryos. Scale bars, 200 μm. (F and G) WT, il8 or csf3r morphants were iv infected with R Mabs (tdTomato, ≈150 CFU). Kinetics of granuloma formation (G) and number of granuloma per infected embryos (H) assessed at 3 dpi. Mean ± SEM from two independent experiments (n = 40). (I) Number of neutrophils recruited to WT or IL8-depleted granulomas as a function of the granuloma volume at 2 dpi. Statistical significance was determined by Kruskal-Wallis test with Dunns post-test (A and H), ANOVA with Tukey post-test (B, C and E), log-rank test (D), Fisher’s exact test of a contingency table (G) or Spearman correlation (I).