title: The surface antigen CD45R identifies a population of estrogen-regulated murine marrow cells that contain osteoclast precursors.
abstract: We examined the osteoclastogenic potential of murine bone marrow cells that were fractionated according to their expression of the surface antigen CD45R. Osteoclast-like cells (OCL) with many authentic osteoclast characteristics readily formed in purified CD45R(+) murine bone marrow cell cultures after treatment with receptor activator of nuclear factor kappaB ligand (RANKL) and M-CSF. Ovariectomy (Ovx) caused a 1.5- to 2-fold increase in OCL number in unfractionated and CD45R(+) murine bone marrow cell cultures without affecting OCL formation in CD45R(-) marrow cells. Limiting dilution assays confirmed that Ovx caused an increase in osteoclast precursor cell number in CD45R(+) but not CD45R(-) cells. Mice deficient in the type 1 IL-1 receptor (IL-1R1 KO) do not lose bone mass after Ovx. We found that unfractionated, CD45R(+), and CD45R(-) bone marrow cells from IL-1R1 KO mice showed no increase in OCL formation in vitro after Ovx. In both the wild-type (WT) and the IL-1R1 KO mice Ovx was associated with a 2-fold increase in pre-B-lymphocytes. About 1.3-3.5% of murine marrow cells expressed surface RANK (the receptor for RANKL) while about 11.9-15% of murine bone marrow cells expressed c-Fms (the receptor for M-CSF). There was little effect of Ovx on cells expressing either RANK or c-Fms. These results demonstrate that CD45R expression identifies a subset of murine bone marrow cells whose ability to form OCL in vivo is regulated by estrogen in WT but not IL-1R1 KO cells. The effects of estrogen on bone mass may be related to these responses.
authors.affiliation: Zagreb University School of Medicine, Zagreb, Croatia.
authors.forename: Vedran
authors.initials: V
authors.lastname: Katavić
authors.forename: Danka
authors.initials: D
authors.lastname: Grcević
authors.forename: Sun Kyeong
authors.initials: SK
authors.lastname: Lee
authors.forename: Judith
authors.initials: J
authors.lastname: Kalinowski
authors.forename: Sandra
authors.initials: S
authors.lastname: Jastrzebski
authors.forename: William
authors.initials: W
authors.lastname: Dougall
authors.forename: Dirk
authors.initials: D
authors.lastname: Anderson
authors.forename: Lynn
authors.initials: L
authors.lastname: Puddington
authors.forename: H Leonardo
authors.initials: HL
authors.lastname: Aguila
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Lorenzo
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D004967:Estrogens / Q000235:genetics / Q000378:metabolism*; D005260:Female; D042381:Granulocyte Precursor Cells / Q000166:cytology / Q000378:metabolism*; D017493:Leukocyte Common Antigens / Q000032:analysis* / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism*; D010052:Ovariectomy; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D051381:Rats; D017472:Receptors, Interleukin-1 / Q000172:deficiency / Q000235:genetics
chemical_list: D004967:Estrogens; D017472:Receptors, Interleukin-1; D017493:Leukocyte Common Antigens; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1