title: G-CSF-mediated thrombopoietin release triggers neutrophil motility and mobilization from bone marrow via induction of Cxcr2 ligands.
abstract: Emergency mobilization of neutrophil granulocytes (neutrophils) from the bone marrow (BM) is a key event of early cellular immunity. The hematopoietic cytokine granulocyte-colony stimulating factor (G-CSF) stimulates this process, but it is unknown how individual neutrophils respond in situ. We show by intravital 2-photon microscopy that a systemic dose of human clinical-grade G-CSF rapidly induces the motility and entry of neutrophils into blood vessels within the tibial BM of mice. Simultaneously, the neutrophil-attracting chemokine KC (Cxcl1) spikes in the blood. In mice lacking the KC receptor Cxcr2, G-CSF fails to mobilize neutrophils and antibody blockade of Cxcr2 inhibits the mobilization and induction of neutrophil motility in the BM. KC is expressed by megakaryocytes and endothelial cells in situ and is released in vitro by megakaryocytes isolated directly from BM. This production of KC is strongly increased by thrombopoietin (TPO). Systemic G-CSF rapidly induces the increased production of TPO in BM. Accordingly, a single injection of TPO mobilizes neutrophils with kinetics similar to G-CSF, and mice lacking the TPO receptor show impaired neutrophil mobilization after short-term G-CSF administration. Thus, a network of signaling molecules, chemokines, and cells controls neutrophil release from the BM, and their mobilization involves rapidly induced Cxcr2-mediated motility controlled by TPO as a pacemaker.
authors.affiliation: Institute of Molecular and Clinical Immunology, Otto-von-Guericke University, Magdeburg, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Köhler
authors.forename: Katia
authors.initials: K
authors.lastname: De Filippo
authors.forename: Mike
authors.initials: M
authors.lastname: Hasenberg
authors.forename: Cindy
authors.initials: C
authors.lastname: van den Brandt
authors.forename: Emma
authors.initials: E
authors.lastname: Nye
authors.forename: Martin P
authors.initials: MP
authors.lastname: Hosking
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Lane
authors.forename: Linda
authors.initials: L
authors.lastname: Männ
authors.forename: Richard M
authors.initials: RM
authors.lastname: Ransohoff
authors.forename: Anja E
authors.initials: AE
authors.lastname: Hauser
authors.forename: Oliver
authors.initials: O
authors.lastname: Winter
authors.forename: Burkhart
authors.initials: B
authors.lastname: Schraven
authors.forename: Hartmut
authors.initials: H
authors.lastname: Geiger
authors.forename: Nancy
authors.initials: N
authors.lastname: Hogg
authors.forename: Matthias
authors.initials: M
authors.lastname: Gunzer
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000276:immunology; D001854:Bone Marrow Cells / Q000166:cytology* / Q000276:immunology; D001842:Bone and Bones / Q000166:cytology; D002460:Cell Line; D002465:Cell Movement; D002478:Cells, Cultured; D016179:Granulocyte Colony-Stimulating Factor / Q000276:immunology*; D006801:Humans; D008533:Megakaryocytes / Q000166:cytology / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D009504:Neutrophils / Q000166:cytology* / Q000276:immunology; D023063:Receptors, Interleukin-8B / Q000276:immunology*; D013926:Thrombopoietin / Q000276:immunology*
chemical_list: D023063:Receptors, Interleukin-8B; D016179:Granulocyte Colony-Stimulating Factor; D013926:Thrombopoietin