title: Distinct osteoclast precursors in the bone marrow and extramedullary organs characterized by responsiveness to Toll-like receptor ligands and TNF-alpha.
abstract: Osteoclasts are derived from hemopoietic stem cells and play critical roles in bone resorption and remodeling. Multinucleated osteoclasts are attached tightly to bone matrix, whereas precursor cells with the potential to differentiate into osteoclasts in culture are widely distributed. In this study, we assessed the characteristics of osteoclast precursors in bone marrow (BM) and in extramedullary organs as indicated by their responsiveness to ligands for Toll-like receptors (TLRs) and to TNF-alpha. Development of osteoclasts from precursor cells in the BM was inhibited by CpG oligonucleotides, a ligand for TLR9, but not by LPS, a ligand for TLR4. BM osteoclasts were induced by TNF-alpha as well as receptor activator of NF-kappaB ligand in the presence of M-CSF. Splenic osteoclast precursors, even in osteoclast-deficient osteopetrotic mice, differentiated into mature osteoclasts following exposure to TNF-alpha or receptor activator of NF-kappaB ligand. However, splenic osteoclastogenesis was inhibited by both LPS and CpG. Osteoclastogenesis from peritoneal precursors was inhibited by not only these TLR ligands but also TNF-alpha. The effects of peptidoglycan, a ligand for TLR2, were similar to those of LPS. BM cells precultured with M-CSF were characterized with intermediate characteristics between those of splenic and peritoneal cavity precursors. Taken together, these findings demonstrate that osteoclast precursors are not identical in the tissues examined. To address the question of why mature osteoclasts occur only in association with bone, we may characterize not only the microenvironment for osteoclastogenesis, but also the osteoclast precursor itself in intramedullary and extramedullary tissues.
authors: Department of Molecular and Cellular Biology, School of Life Science, Faculty of Medicine, Institute of Regenerative Medicine and Biofunction, Graduate School of Medical Science, Tottori University, Tottori, Japan. shayashi@grape.med.tottori-u.ac.jp
authors: Shin-Ichi
authors: S
authors: Hayashi
authors: Takayuki
authors: T
authors: Yamada
authors: Motokazu
authors: M
authors: Tsuneto
authors: Toshiyuki
authors: T
authors: Yamane
authors: Masayuki
authors: M
authors: Takahashi
authors: Leonard D
authors: LD
authors: Shultz
authors: Hidetoshi
authors: H
authors: Yamazaki
mesh_terms: D000818:Animals; D001202:Ascitic Fluid / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D001854:Bone Marrow Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology; D002454:Cell Differentiation / Q000276:immunology; D002460:Cell Line; D002478:Cells, Cultured; D002999:Clone Cells; D006023:Glycoproteins / Q000378:metabolism; D006131:Growth Inhibitors / Q000494:pharmacology; D007108:Immune Tolerance / Q000276:immunology; D007275:Injections, Intravenous; D008024:Ligands; D008070:Lipopolysaccharides / Q000494:pharmacology; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000276:immunology; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008822:Mice, Transgenic; D009838:Oligodeoxyribonucleotides / Q000008:administration & dosage / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D010022:Osteopetrosis / Q000235:genetics / Q000473:pathology; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D011956:Receptors, Cell Surface / Q000378:metabolism* / Q000502:physiology; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor; D015398:Signal Transduction / Q000276:immunology; D013154:Spleen / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D017154:Stromal Cells / Q000166:cytology / Q000276:immunology; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
chemical_list: C408982:CPG-oligonucleotide; D002352:Carrier Proteins; D006023:Glycoproteins; D006131:Growth Inhibitors; D008024:Ligands; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D009838:Oligodeoxyribonucleotides; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C505687:Tnfrsf11a protein, mouse; C506031:Tnfrsf11b protein, mouse; C505689:Tnfsf11 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha; D016173:Macrophage Colony-Stimulating Factor