Effect of beclomethasone on Mm infection burden in zebrafish. (A) Bacterial burden of zebrafish larvae at four days after intravenous injection (at 28 hpf) of Mm and treatment with vehicle or different concentrations of beclomethasone (beclo), started at 2 h before infection. Statistical analysis by one-way ANOVA with Bonferroni’s post hoc test revealed that the bacterial burden was significantly increased in the group treated with 25 µM beclomethasone, compared to the burden of the vehicle-treated group. (B) Effect of the GR antagonist RU-486 on the beclomethasone-induced increase of the bacterial burden at 4 dpi. The bacterial burden was significantly increased by beclomethasone (25 µM) treatment and this increase was abolished in the presence of RU-486. Statistical analysis was performed by two-way ANOVA with Tukey’s post hoc test. In panels (A, B), each data point represents a single larva and the means ± s.e.m. of data accumulated from three independent experiments are shown in red. Statistical significance is indicated by: ns, non-significant; *P<0.05; ***P<0.001; ****P<0.0001. (C, D) Representative fluorescence microscopy images of Mm-infected larvae at 4 days post infection (dpi), representing experimental groups presented in panels (A, B) Bacteria are shown in green. Scale bar = 200 μm.
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