RNAseq profiling of FACS-sorted zebrafish larval macrophages reveals similarities with human M1 and M2 transcriptome signatures

We used different zebrafish transgenic lines to sort macrophages, neutrophils and immature lymphoid cells from 5-6 day old zebrafish larvae and analyzed their transcriptomes. Comparison between the different transcriptomes and gene ontology analysis revealed specificities for each cell population. Comparison with previously published data showed that zebrafish larval macrophages expressed several known human M1 and M2 macrophages. Transcriptome analysis of uninfected and infected macrophages from embryos infected by of Mycobacterium marinum revealed infection induced transcriptional changes and a shift towards M1 transcriptomic signature. Embryos were grown into egg water refresh every day and incubated for 5 or 6 days at 28°C. 0.003% 1-phenyl-2-thiourea (Sigma-Aldrich) was added after 1 day to prevent melanisation. After the incubation period, embryos were dissociated into single cell suspension by Trypsin treatment and fluorescent cells were sorted by FACS. RNA extraction and library preparation were performed as previously described. (Rougeot et al., 2014, Methods Mol Biol 1197:41-66). For infection experiments, zebrafish embryos were manually dechorionated at 24 hours post fertilization (hpf) and were infected by injection in the caudal vein of 125 colony forming unit of Mycobacterium marinum M strain expressing GFP. Infected larvae were collected for FACS sorting 5 day post infection.