title: B-1 lymphocytes differentiate into functional osteoclast-like cells.
abstract: The existence of murine peritoneal osteoclast precursors has been already described. Also, recent reports evidenced an interplay between B lymphocytes and osteoclasts development. B-1 cells comprise a B-lymphocyte subset that resides mostly in pleural and peritoneal cavities. It has been demonstrated that B-1 cells can differentiate into mononuclear phagocytes and form multinucleated giant cells. Based on these findings, we investigated the role of B-1 lymphocytes in bone resorption and osteoclastogenesis. In vivo experimental periodontitis induced in B-1 deficient Xid mice demonstrated that bone resorption is impaired in these animals. However, reconstitution of Xid mice with B-1 cells increased bone resorption to near Balb/c values. B-1 cell derived phagocytes express the receptor activator of nuclear factor-κB (RANK) and the macrophage colony-stimulating factor receptor (M-CSFR). When cultured with RANK-ligand (RANKL) and M-CSF, B-1 cells became tartrate resistant acid phosphatase (TRAP) positive multinucleated cells, a typical osteoclast phenotype. Lacunae formation was observed when cells were cultivated onto a calcium phosphate analog, indicating functional differentiation of B1 cells into osteoclast-like cells. The dynamics of their IgM expression showed that this lymphoid marker was downregulated along the differentiation of B-1 lymphocytes into osteoclasts. Our results unveiled the first evidence that B-1 cells have a role in osteoclastogenesis and bone resorption and offer new insights in the relationship between bone and lymphoid cells.
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Instituto de Ciências Biomédicas, Universidade Federal de São Paulo. Rua Botucatu 862/4 andar, 04023-009 São Paulo, SP, Brazil.
authors.forename: Livia Souza
authors.initials: LS
authors.lastname: Pugliese
authors.forename: Thais Oliveira
authors.initials: TO
authors.lastname: Gonçalves
authors.forename: Ana Flávia
authors.initials: AF
authors.lastname: Popi
authors.forename: Mario
authors.initials: M
authors.lastname: Mariano
authors.forename: João Bosco
authors.initials: JB
authors.lastname: Pesquero
authors.forename: José Daniel
authors.initials: JD
authors.lastname: Lopes
mesh_terms: D000818:Animals; D016175:B-Lymphocyte Subsets / Q000166:cytology* / Q000378:metabolism*; D001862:Bone Resorption; D054338:Cell Transdifferentiation / Q000187:drug effects; D002478:Cells, Cultured; D016130:Immunophenotyping; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D010010:Osteoclasts / Q000166:cytology* / Q000378:metabolism*; D010586:Phagocytes / Q000166:cytology / Q000378:metabolism; D053245:RANK Ligand / Q000494:pharmacology; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000378:metabolism; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000378:metabolism
chemical_list: D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D016173:Macrophage Colony-Stimulating Factor; D016186:Receptor, Macrophage Colony-Stimulating Factor