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  • MICE  (4)
  • 1
    Keywords: RECEPTOR ; EXPRESSION ; Germany ; IN-VIVO ; DIFFERENTIATION ; MICE ; BONE-MARROW ; MOUSE ; NATURAL-KILLER-CELLS ; HEMATOPOIETIC PROGENITOR CELLS ; LYMPHOID ORGANS ; dendritic cell ; HOMEOSTASIS ; STEADY-STATE ; FLT3 LIGAND
    Abstract: Bone marrow-derived dendritic cell (DC) precursors seed peripheral organs, where they encounter diverse cellular environments during their final differentiation into DCs. Flt3 ligand (Flt3-L) is critical for instructing DC generation throughout different organs. However, it remains unknown which cells produce Flt3-L and, importantly, which cellular source drives DC development in such a variety of organs. Using a novel BAC transgenic Flt3-L reporter mouse strain coexpressing enhanced GFP and luciferase, we show ubiquitous Flt3-L expression in organs and cell types. These results were further confirmed at the protein level. Although Flt3-L was produced by immune and nonimmune cells, the source required for development of the DC compartment clearly differed among organs. In lymphoid organs such as the spleen and bone marrow, Flt3-L production by hemopoietic cells was critical for generation of normal DC numbers. This was unexpected for the spleen because both immune and nonimmune cells equally contributed to the Flt3-L content in that organ. Thus, localized production rather than the total tissue content of Flt3-L in spleen dictated normal splenic DC development. No differences were observed in the number of DC precursors, suggesting that the immune source of Flt3-L promoted pre-cDC differentiation in spleen. In contrast, DC generation in the lung, kidney, and pancreas was mostly driven by nonhematopoietic cells producing Flt3-L, with little contribution by immune cells. These findings demonstrate a high degree of flexibility in Flt3-L-dependent DC generation to adapt this process to organ-specific cellular environments encountered by DC precursors during their final differentiation.
    Type of Publication: Journal article published
    PubMed ID: 22198954
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  • 2
    Keywords: CANCER ; EXPRESSION ; CELL ; Germany ; IN-VIVO ; THERAPY ; VIVO ; SYSTEM ; TOOL ; liver ; GENE ; GENE-EXPRESSION ; GENES ; PROTEIN ; MICE ; MACROPHAGES ; INDUCTION ; tumour ; BIOLOGY ; culture ; MOUSE ; gene expression ; VECTORS ; PROMOTER ; REGION ; VACCINES ; REGIONS ; DELIVERY ; Jun ; CARRIERS ; GREEN FLUORESCENT PROTEIN ; LUCIFERASE ; CYTOSINE DEAMINASE ; RE ; THERAPIES ; REPORTER GENE ; CARRIER ; HISTOLOGY ; in vivo ; E ; TOOLS ; spleen ; microbiology ; ENGLAND ; host ; FLUORESCENT PROTEIN ; FLUORESCENT ; PLASMIDS ; bacterial ; ARABAD PROMOTER ; tumour therapy
    Abstract: We have used Salmonella enterica serovar Typhimurium (S. typhimurium) which are able to colonize tumours besides spleen and liver. Bacteria were equipped with constructs encoding green fluorescent protein or luciferase as reporters under control of the promoter P-BAD that is inducible with L-arabinose. Reporter genes could be induced in culture but also when the bacteria resided within the mouse macrophages J774A.1. More important, strong expression of reporters by the bacteria could be detected in mice after administration of L-arabinose. This was especially pronounced in bacteria colonizing tumours. Histology demonstrated that the bacteria had accumulated in and close to necrotic areas of tumours. Bacterial gene induction was observed in both regions. P-BAD is tightly controlled also in vivo because gene E of bacteriophage Phi X174 could be introduced as inducible suicide gene. The possibility to deliberately induce genes in bacterial carriers within the host should render them extremely powerful tools for tumour therapy
    Type of Publication: Journal article published
    PubMed ID: 17298393
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  • 3
    Keywords: CANCER ; EXPRESSION ; tumor ; Germany ; IN-VIVO ; THERAPY ; VIVO ; SYSTEMS ; GENE ; GENE-EXPRESSION ; MOLECULES ; TISSUE ; MICE ; INDUCTION ; gene expression ; ESCHERICHIA-COLI ; VECTOR ; PROMOTER ; NETHERLANDS ; BIOLUMINESCENCE ; ENGINEERED BACTERIA ; Gall bladder ; In vivo imaging ; Inducible promoter ; Organ colonization ; Tumor targeted bacteria
    Abstract: The probiotic bacterium Escherichia coli Nissle 1917 (EcN) constitutes a prospective vector for delivering heterologous therapeutic molecules to treat several human disorders. To add versatility to this carrier system, bacteria should be equipped with expression modules that can be regulated deliberately in a temporal and quantitative manner. This approach is called in vivo remote control (IVRC) of bacterial vectors. Here, we have evaluated promoters P-araBAD, P-rhaBAD and P-tet, which can be induced with L-arabinose, L-rhamnose or anhydrotetracycline, respectively. EcN harboring promoter constructs with luciferase as reporter gene were administered either orally to healthy mice or intravenously to tumor bearing animals. Subsequent to bacterial colonization of tissues, inducer substances were administered via the oral or systemic route. By use of in vivo bioluminescence imaging, the time course of reporter gene expression was analyzed. Each promoter displayed a specific ill vivo induction profile depending on the niche of bacterial residence and the route of inducer administration. Importantly, we also observed colonization of gall bladders of mice when EcN was administered systemically at high doses. Bacteria in this anatomical compartment remained accessible to remote control of bacterial gene expression.
    Type of Publication: Journal article published
    PubMed ID: 19665575
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  • 4
    Keywords: CELLS ; IN-VITRO ; tumor ; TUMOR-CELLS ; CELL ; Germany ; IN-VIVO ; LUNG ; VITRO ; VIVO ; imaging ; SYSTEM ; PROTEIN ; PROTEINS ; TISSUE ; MICE ; NUCLEAR-MEDICINE ; animals ; TISSUES ; SIGNAL ; NUMBER ; ATTENUATION ; TUMOR CELLS ; LUCIFERASE ; nuclear medicine ; LOCATION ; ABSORPTION ; radiology ; RE ; methods ; TUMOR-CELL ; bioluminescence imaging ; NUCLEAR ; USA ; CANDIDATE ; in vivo ; animal ; PHOTON ; MEDICINE ; comparison ; quantitative ; EMISSION ; OCCURS ; 2A systems ; BIOLUMINESCENCE
    Abstract: For bioluminescence imaging (BLI) of small animals, the most commonly used luciferase is Fluc from the firefly, but recently, green (CBGr99) and red (CBRed) click beetle luciferases became available. Because signal attenuation by tissues is lower for red light, red luciferases appear to be advantageous for BLI, but this has not been thoroughly tested. We compare different luciferases for BLI. For this purpose, cell transfectants are generated expressing comparable amounts of CBGr99, CBRed, or Fluc. This is achieved by coexpression of the luciferase with eGFP using the bicistronic 2A system, which results in stoichiometric coexpression of the respective proteins. In vitro, the CBGr99 transfectant exhibits the strongest total photon yield. For in vivo BLI, the transfectants are injected into mice at different locations. At a subcutaneous position, CBGr99 is clearly superior to the other luciferases. When the tumor cells are located in the peritoneum or lung, where more absorption by tissue occurs, CBGr99 and CBRed transfected cells emit a comparable number of red photons and are superior to Fluc, but CBGr99 reaches the maximum of the light emission faster than CBRed. Thus, although CBGr99 emits mainly green light, the high yield of total and red photons makes it an excellent candidate for BLI. (C) 2007 Society of Photo-Optical Instrumentation Engineers
    Type of Publication: Journal article published
    PubMed ID: 17994906
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