Redundant Trojan horse and endothelial-circulatory mechanisms for host-mediated spread of Candida albicans yeast
Fig 7
Wild type C. albicans mirrors yeast-locked strain.
Tg(Mpeg:GAL4)/(UAS:nfsB-mCherry)/Tg(mpx:EGFP) or RAC2-D57N/Tg(tnfα:GFP) larvae were injected with control or clodronate liposomes and infected with the wild type Caf2-iRFP C. albicans as described for the yeast-locked infections. (A) Dissemination dynamics for wildtype fungi are similar to dynamics for yeast-locked and are unaffected by macrophage ablation. Tg(Mpeg:GAL4)/(UAS:nfsB-mCherry)/Tg(mpx:EGFP) were infected and scored for immune recruitment and dissemination of yeast between 24 and 40 hpi, as described in Fig 1B. Top circles represent the percentages of fish at 24 hpi, colored with the indicated recruitment/dissemination phenotype. Bottom bars represent phenotypes at 40 hpi, grouped based on their 24 hpi phenotype. Pooled from 2 experiments, control larvae n = 16, clodronate larvae n = 21. (B) Representative images of Recruited/Non-disseminated Tg(Mpeg:GAL4)/(UAS:nfsB-mCherry)/Tg(mpx:EGFP) larvae treated with control or clodronate liposomes at 40 hpi. Area in yellow shows the yolk sac outline. Scale bar = 50 μm. (C) Dissemination of wildtype yeast does not require intact phagocytes. Percent dissemination of Tg(Mpeg:GAL4)/(UAS:nfsB-mCherry)/Tg(mpx:EGFP) larvae (left) and RAC2-D57N/Tg(tnfα:GFP) larvae (right) at 40 hpi. Right: Pooled from 2 experiments as in panel A. Left: Pooled from 3 experiments. Fisher’s exact test, n.s. (D) Wildtype elicits a macrophage-dependent expression of TNFα. Representative images of control (left) and clodronate (right) treated Rac2-D57N/Tg(tnfα:GFP) larvae. Yellow outlines the yolk sac. Scale bar = 100 μm. (E) Pixel area of host cells expressing tnfα during wild type C. albicans infection. Pooled from 3 experiments. (F) Fungal burden quantified as fluorescent pixels in z-stack images (for each time-point, from left to right n = 8, 3, 8, 7, 10, 6, 10 and 6 larvae). Stats: Kruskal-Wallis with Dunn’s post-test, * p ≤ 0.05, ** p ≤ 0.01, *** p ≤ 0.001., **** p ≤ 0.0001, n.s. p > 0.05. Bars indicate the mean and SEM.