Project description:We use the zebrafish embryo model to study the similarities and differences in the innate immune response against three different bacterial pathogens. Therefore, we injected E. tarda, Salmonella, or M. marinum into the caudal vein of 28 hours post fertilization (hpf) zebrafish embryos and analysed their gene expression profile at 8 hours or 4 days after infection by microarrays. The results show that infections with the gram-negative bacteria E. tarda and S. typhimurium, which are lethal within 1-2 days, induce a strong early immune response at 8 hours after infection. In contrast, infection with M. marinum leads to a chronic infection that only induces a strong response at 4 days post infection. This microarray study was designed to determine the gene expression profile during infection with Salmonella typhimurium, Mycobacterium marinum, and Edwardsiella tarda. RNA was isolated from single embryos and each treatment group consisted of three embryos: (1) Wildtypes injected with PBS 8 hours post infection (hpi), (2) S. typhimurium-infected wildtypes 8hpi, (3) wildtypes injected with PBS/2%PVP 8hpi , (4) M. marinum-infected wildtypes 8hpi, (5) wildtypes injected with PBS/2%PVP 4 days post infection (dpi), (6) M. marinum-infected wildtypes 4dpi, (7) wildtypes injected with PBS 8hpi (E. tarda control), (8) E. tarda-infected wildtypes 8hpi. Embryos were grown at 28.5M-bM-^@M-^S30M-BM-0C in egg water and manually dechorionated at 24 hours post fertilization (hpf). Subsequently, embryos were infected at 28 hpf by micro-injecting 200 colony forming units (CFU) of S. typhimurium SL1027, E. tarda or Mycobacteria marinum M20 bacteria into the caudal vein, or were mock-injected with buffer as a control. After injections embryos were transferred into fresh egg water and incubated for 8 h or 4 days at 28M-BM-0C. After the incubation period, single embryos were snap-frozen in liquid nitrogen and RNA was isolated for microarray analysis. All treatment groups were analyzed using a common reference approach.

Project description:MyD88 is an adaptor protein in Toll-like receptor and interleukin 1 receptor mediated signaling pathways that plays an essential role in activation of immune responses following pathogen recognition. We investigate that role in the zebrafish embryo model by using a zebrafish mutant line that contains a premature stop condon in the gene encoding MyD88, leading to a truncated protein that lacks domains important for its normal function. We infected these MyD88 mutants and wildtype individuals with Salmonella typhimurium and Edwardsiella tarda to compare the resulting immune response by transcriptome profiling on total RNA isolated from single embryos. The data derived from these microarray experiments confirms the vital role of MyD88 in pathogen recognition and provides many leads for further research. This microarray study was designed to determine the effect of a truncation of the MyD88 protein on the innate immune response of zebrafish embryos during infection with Salmonella typhimurium and Edwardsiella tarda. Embryos used in this study are derived from an incross between parents heterozygous for the mutation. Both homozygous mutants and their wildtype siblings were selected by genotyping after being injected with the bacteria or PBS as control. RNA was isolated from single embryos and each treatment group consisted of three embryos: (1) Homozygous mutants injected with PBS 8 hours post infection (hpi), (2) wildtype siblings injected with PBS 8hpi, (3) S. typhimurium-infected homozygous mutants 8hpi, (4) S. typhimurium-infected wildtype siblings 8hpi, (5) Homozygous mutants injected with PBS 8 hours post infection (hpi) (E.tarda control), (6) wildtype siblings injected with PBS 8hpi (E. tarda control), (7) E. tarda-infected homozygous mutants 8hpi, (8) E. tarda-infected wildtype siblings 8hpi. Embryos were grown at 28.5M-bM-^@M-^S30M-BM-0C in egg water and manually dechorionated at 24 hours post fertilization (hpf). Subsequently, embryos were infected at 28 hpf by micro-injecting 200 colony forming units (CFU) of S. typhimurium SL1027 or E. Tarda FL-F60, or were mock-injected with buffer as a control. After injections embryos were transferred into fresh egg water and incubated for 8 h or 4 days at 28M-BM-0C. After the incubation period, single embryos were snap-frozen in liquid nitrogen and RNA was isolated for microarray analysis. All treatment groups were analyzed using a common reference approach.

Project description:Deficiency in the protein-tyrosine phosphatase SHP1/PTPN6 is linked with hematological malignancies and chronic inflammatory diseases. Here we exploited the embryonic and larval stages of zebrafish as an animal model to study ptpn6 function in the sole context of innate immunity. We show that ptpn6 knockdown induces a spontaneous inflammation-associated phenotype at the late larval stage, which was microbe-independent and enhanced instead of suppressed by glucocorticoids. When challenged with Salmonella typhimurium or Mycobacterium marinum at earlier stages of development, the innate immune system was hyperactivated to a contra-productive level that impaired the control of these pathogenic bacteria. These results demonstrate the crucial regulatory function of ptpn6 in preventing host-detrimental effects of inflammation by imposing a tight control over the level of innate immune response activation. This microarray study was designed to determine the effect of morpholino knockdown of the ptpn6 gene on the innate immune response of zebrafish embryos during infection with Salmonella typhimurium. Three independent infection experiments were performed using mixed egg clutches of wild type zebrafish, which were a cross of the AB and TL strains. Each experiment consisted of the following four treatment groups: (1) uninfected control embryos, (2) S. typhimurium-infected control embryos, (3) uninfected ptpn6 knockdown embryos, and (4) S. typhimurium-infected ptpn6 knockdown embryos. Knockdown of ptpn6 was performed by micro-injecting embryos at the 1-2 cell stage with the ptpn6 morpholino, and control embryos were mock-injected with buffer. Embryos were grown at 28.5M-bM-^@M-^S30M-BM-0C in egg water and manually dechorionated at 24 hours post fertilization (hpf). Subsequently, embryos were infected at 28 hpf by micro-injecting 200-250 colony forming units (CFU) of S. typhimurium SL1027 bacteria into the caudal vein, or were mock-injected with buffer as a control. After injections embryos were transferred into fresh egg water and incubated for 8 h at 28M-BM-0C. After the incubation period, pools of 15-20 embryos per treatment group were snap-frozen in liquid nitrogen and RNA was isolated for microarray analysis. All treatment groups were analyzed using a common reference approach.

Project description:MyD88 is an adaptor protein in Toll-like receptor and interleukin 1 receptor mediated signaling pathways that plays an essential role in activation of immune responses following pathogen recognition. We investigate that role in the zebrafish embryo model by using a zebrafish mutant line that contains a premature stop condon in the gene encoding MyD88, leading to a truncated protein that lacks domains important for its normal function. We infected these MyD88 mutants and wildtype individuals with S Mycobacterium marinum to compare the resulting immune response by transcriptome profiling on total RNA isolated from single embryos. Autophagy regulator dram1 was identified as one of the MyD88-dependent genes. This microarray study was designed to determine the effect of a truncation of the MyD88 protein on the innate immune response of zebrafish embryos during infection with Mycobacterium marinum. Embryos used in this study are derived from an incross between parents heterozygous for the mutation. Both homozygous mutants and their wildtype siblings were selected by genotyping after being injected with the bacteria or PBS as control. RNA was isolated from single embryos at 4 days post infection (4 dpi) and each treatment group consisted of three embryos: (1) Homozygous mutants mock-injected with PBS/2%PVP 4 dpi, (2) wildtype siblings mock-injected with PBS/2%PVP 4dpi, (3) M. marinum-infected homozygous mutants 4dpi, (4) M. marinum-infected wildtype siblings 4dpi. Embryos were grown at 28.5M-bM-^@M-^S30M-BM-0C in egg water and manually dechorionated at 24 hours post fertilization (hpf). Subsequently, embryos were infected at 28 hpf by micro-injecting 200 colony forming units (CFU) of Mycobacterium marinum Mma20 bacteria into the caudal vein, or were mock-injected with buffer (PBS/2%PVP) as a control. After injections embryos were transferred into fresh egg water and incubated for 4 days at 28M-BM-0C. After the incubation period, single embryos were snap-frozen in liquid nitrogen and RNA was isolated for microarray analysis. The treatment groups were analyzed using a common reference approach.

Project description:The Spi1/ Pu.1 transcription factor plays a crucial role in myeloid cell development across many species. Several Spi1 target genes have been identified so far, yet the Spi1-dependent gene group remains largely unknown. To identify novel genes downstream of Spi1 we employed a microarray strategy using zebrafish embryos. We established the gene group down-regulated upon spi1 knockdown while simultaneously enriched in FACS-sorted embryonic myeloid cells of a spi1:GFP transgenic line, thus representing putative myeloid-specific Spi1 target genes. This gene group contained all previously identified Spi1-dependent zebrafish genes, confirming the validity of the approach, as well as novel immune-related genes. Colocalization studies with neutrophil and macrophage markers revealed that genes cxcr3.2, mpeg1, ptpn6 and mfap4 were expressed specifically in early embryonic macrophages. The analysis of adult zebrafish hematopoietic tissue showed that genes mfap4 and mpeg1 remained macrophage specific within the myeloid fraction throughout zebrafish life. We also demonstrated that gene cxcr3.2, coding for chemokine receptor 3.2, functions in macrophage migration to the site of bacterial infection. These results establish a myeloid-specific gene group dependent on Spi1 in zebrafish and identify novel early macrophage-specific marker genes, which will facilitate further studies of macrophage development and innate immune function. Zebrafish strains Zebrafish (Danio rerio) were handled in compliance with the local animal welfare regulations and maintained according to standard protocols (http://ZFIN.org). The spi1-gfp transgenic line used in this study (Pu1-lynEGFP, a gift from Franscesca Peri, EMBL, Heidelberg) contains 4 kb of spi1/pu.1 promoter sequence driving expression of membrane-targeted EGFP. Morpholino knock-down experiments Morpholino oligonucleotides (Gene Tools) were diluted to required concentration in 1x Danieu’s buffer (58 mM NaCl, 0.7 mM KCl, 0.4 mM MgSO4, 0.6 mM Ca(NO3)2, 5.0 mM HEPES; pH 7.6) containing 1% Phenol red (Sigma) and approximately 1 nl was injected into the 1-2 cell stage embryo using a Femtojet injector (Eppendorf). Embryo dissociation and FACS (Fluorescent activated cell sorting) Dissociation of embryos was performed according to Covassin et al. 30. In short, ~300 embryos of spi1:GFP line at 28 hpf were dechorionated by pronase treatment, rinsed in calcium free Ringer solution, followed by digestion with 0.25% trypsin. The obtained cell suspension was centrifuged, rinsed with PBS and resuspended in Leibovitz medium L15 without phenol red, 1% fetal calf serum, 0.8mM CaCl2, penicillin 50 U/ml and streptomycin 0.05 mg/ml. The single cell suspension was subject to FACS at room temperature using a FACSAria (Becton Dickinson) with the BD FACSDiva software version 5.0.3 and a Coherent Sapphire solid state laser 488 nm with 13 mW power. The GFP+ and GFP- cell fractions were collected separately into L15 medium supplemented with 0.8 mM CaCl2, 10% fetal calf serum and penicillin 50 U/ml and streptomycin 0.05 mg/ml. The standard yield from circa 300 embryos was approximately 2 x 105 GFP+ cells. Microarray experiment design and analysis Embryos injected either with 1 mM Pu1 morpholino19 or 1 mM Standard Control morpholino were harvested at 28 hours post fertilization (hpf). As a control, embryos injected with an equal volume of 1% Phenol red in Danieu’s buffer (1xPR/D) were used. Pools of 20-30 embryos were collected. RNA samples from spi1 morphants and standard control morphants were labelled with Cy5 and hybridized against a Cy3-labelled common reference (a mixture of all samples injected with 1xPR/D). This experiment was performed in triplicate. FACS sorted spi1-GFP zebrafish embryos at 28hpf were analyzed as follows: the RNA of GFP-positive fraction was labelled with Cy5 and hybridized against a Cy3-labelled RNA of corresponding GFP-negative fraction of cells from the same pool of embryos. This experiment was performed in duplicate. RNA isolation, synthesis of amino allyl labeled aRNA, coupling of Cy3 and Cy5 dyes, and hybridization conditions were as described31. Microarray analysis was performed using custom-designed 44k Agilent chips (platform accession number in GEO: GPL7735) described elsewhere 31. Microarray data were processed and analyzed as described 31. Significance cut-offs for differentially expressed probe sequences were set at 1.2 fold change at P <10-2.

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Transcriptome analysis of the zebrafish embryonic host response to Edwardsiella tarda infection

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