title: CCR2 inhibition sequesters multiple subsets of leukocytes in the bone marrow.
abstract: Chemokine receptor CCR2 mediates monocyte mobilization from the bone marrow (BM) and subsequent migration into target tissues. The degree to which CCR2 is differentially expressed in leukocyte subsets, and the contribution of CCR2 to these leukocyte mobilization from the BM are poorly understood. Using red fluorescence protein CCR2 reporter mice, we found heterogeneity in CCR2 expression among leukocyte subsets in varying tissues. CCR2 was highly expressed by inflammatory monocytes, dendritic cells, plasmacytoid dendritic cells and NK cells in all tissues. Unexpectedly, more than 60% of neutrophils expressed CCR2, albeit at low levels. CCR2 expression in T cells, B cells and NK T cells was greatest in the BM compared to other tissues. Genetic CCR2 deficiency markedly sequestered all leukocyte subsets in the BM, with reciprocal reduction noted in the peripheral blood and spleen. CCR2 inhibition via treatment with CCR2 signaling inhibitor propagermanium produced similar effects. Propagermanium also mitigated lipopolysaccharide-induced BM leukocyte egress. Consistent with its functional significance, CCR2 antibody staining revealed surface CCR2 expression within a subset of BM neutrophils. These results demonstrate the central role CCR2 plays in mediating leukocyte mobilization from the BM, and suggest a role for CCR2 inhibition in managing monocytes/macrophages-mediated chronic inflammatory conditions.
authors.affiliation: 1] Departments of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA [2] Department of Vascular Surgery, Saiseikai Central Hospital, Minato-Ku Mita 1-4-17, Tokyo 108-0073, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Fujimura
authors.affiliation: Departments of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Baohui
authors.initials: B
authors.lastname: Xu
authors.affiliation: Departments of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Jackson
authors.initials: J
authors.lastname: Dalman
authors.affiliation: Departments of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Hongping
authors.initials: H
authors.lastname: Deng
authors.affiliation: Department of Hygiene and Health Promotion Medicine, Kagoshima University School of Medicine, Sakuragaoka 8-35-1, Kagoshima 890-0075, Japan.
authors.forename: Kohji
authors.initials: K
authors.lastname: Aoyama
authors.affiliation: Departments of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Dalman
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation; D005857:Germanium; D007962:Leukocytes / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D009942:Organometallic Compounds / Q000494:pharmacology; D011422:Propionates; D054390:Receptors, CCR2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: C515335:Ccr2 protein, mouse; D009942:Organometallic Compounds; D011422:Propionates; D054390:Receptors, CCR2; D005857:Germanium; C066750:propagermanium