title: Visualization of bone marrow monocyte mobilization using Cx3cr1gfp/+Flt3L-/- reporter mouse by multiphoton intravital microscopy.
abstract: Monocytes are innate immune cells that play critical roles in inflammation and immune defense. A better comprehension of how monocytes are mobilized and recruited is fundamental to understand their biologic role in disease and steady state. The BM represents a major "checkpoint" for monocyte homeostasis, as it is the primary site for their production and release. Our study determined that the Cx3cr1(gfp/+) mouse strain is currently the most ideal model for the visualization of monocyte behavior in the BM by multiphoton intravital microscopy. However, we observed that DCs are also labeled with high levels of GFP and thus, interfere with the accuracy of monocyte tracking in vivo. Hence, we generated a Cx3cr1(gfp/+)Flt3L(-/-) reporter mouse and showed that whereas monocyte numbers were not affected, DC numbers were reduced significantly, as DCs but not monocytes depend on Flt3 signaling for their development. We thus verified that mobilization of monocytes from the BM in Cx3cr1(gfp/+)Flt3L(-/-) mice is intact in response to LPS. Collectively, our study demonstrates that the Cx3cr1(gfp/+)Flt3L(-/-) reporter mouse model represents a powerful tool to visualize monocyte activities in BM and illustrates the potential of a Cx3cr1(gfp/+)-based, multifunctionality fluorescence reporter approach to dissect monocyte function in vivo.
authors.affiliation: *Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; and School of Biological Sciences, Nanyang Technological University, Singapore Ng_Lai_Guan@immunol.a-star.edu.sg maximilien_evrard@immunol.a-star.edu.sg.
authors.forename: Maximilien
authors.initials: M
authors.lastname: Evrard
authors.affiliation: *Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; and School of Biological Sciences, Nanyang Technological University, Singapore.
authors.forename: Shu Zhen
authors.initials: SZ
authors.lastname: Chong
authors.affiliation: *Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; and School of Biological Sciences, Nanyang Technological University, Singapore.
authors.forename: Sapna
authors.initials: S
authors.lastname: Devi
authors.affiliation: *Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; and School of Biological Sciences, Nanyang Technological University, Singapore.
authors.forename: Weng Keong
authors.initials: WK
authors.lastname: Chew
authors.affiliation: *Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; and School of Biological Sciences, Nanyang Technological University, Singapore.
authors.forename: Bernett
authors.initials: B
authors.lastname: Lee
authors.affiliation: *Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; and School of Biological Sciences, Nanyang Technological University, Singapore.
authors.forename: Michael
authors.initials: M
authors.lastname: Poidinger
authors.affiliation: *Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; and School of Biological Sciences, Nanyang Technological University, Singapore.
authors.forename: Florent
authors.initials: F
authors.lastname: Ginhoux
authors.affiliation: *Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; and School of Biological Sciences, Nanyang Technological University, Singapore.
authors.forename: Suet Mien
authors.initials: SM
authors.lastname: Tan
authors.affiliation: *Singapore Immunology Network, Agency for Science, Technology and Research, Biopolis, Singapore; and School of Biological Sciences, Nanyang Technological University, Singapore Ng_Lai_Guan@immunol.a-star.edu.sg maximilien_evrard@immunol.a-star.edu.sg.
authors.forename: Lai Guan
authors.initials: LG
authors.lastname: Ng
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology* / Q000187:drug effects; D000073883:CX3C Chemokine Receptor 1; D002452:Cell Count; D048430:Cell Shape / Q000187:drug effects; D003713:Dendritic Cells / Q000166:cytology / Q000187:drug effects; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008565:Membrane Proteins / Q000172:deficiency* / Q000378:metabolism; D051379:Mice; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D009000:Monocytes / Q000166:cytology* / Q000187:drug effects; D010641:Phenotype; D054390:Receptors, CCR2 / Q000378:metabolism; D019707:Receptors, Chemokine / Q000378:metabolism*; D012886:Skull / Q000166:cytology
chemical_list: D000073883:CX3C Chemokine Receptor 1; C515335:Ccr2 protein, mouse; C471885:Cx3cr1 protein, mouse; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D054390:Receptors, CCR2; D019707:Receptors, Chemokine; C084881:flt3 ligand protein; D049452:Green Fluorescent Proteins
keywords: dendritic cells; live imaging; macrophages; trafficking