title: Phosphatidylserine-containing liposomes inhibit the differentiation of osteoclasts and trabecular bone loss.
abstract: Liposomes containing phosphatidylserine (PS) are engulfed by phagocytes including macrophages, microglia, and dendritic cells. PS liposomes (PSLs) mimic the effects of apoptotic cells on these phagocytes to induce the secretion of anti-inflammatory molecules and to inhibit the maturation of dendritic cells. However, the effects of PSLs on osteoclasts, which are also differentiated from the common myeloid precursors, remain to be determined. This study investigated the effects of PSLs on the osteoclastogenesis. In the rat bone marrow culture system, osteoclast precursors phagocytosed PSLs to secrete TGF-beta1 and PGE(2), which in turn inhibited osteoclastogenesis through the downregulation of receptor activator for NF-kappaB ligand, receptor activator of NF-kappaB, ICAM-1, and CD44. Consistent with these in vitro observations, i.m. injection of PSLs significantly increased the plasma level of TGF-beta1 and PGE(2) and decreased the expression of receptor activator for NF-kappaB ligand, receptor activator of NF-kappaB, and ICAM-1 in the skeletal tissues of ankle joints of rats with adjuvant arthritis (AA). A quantitative analysis using microcomputed tomography revealed that PSLs as well as TGF-beta1 together with PGE(2) significantly inhibited AA-induced trabecular bone loss. These observations strongly suggest that PSLs generate TGF-beta1 and PGE(2) release, leading to inhibit osteoclastogenesis and AA-induced trabecular bone loss. Because PS is a component of the cell membrane, PSLs therefore can be a potentially effective pharmacological intervention against abnormal bone loss, such as osteoporosis without deleterious side effects.
authors.affiliation: Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka, Japan. zhouw@dent.kyushu-u.ac.jp
authors.forename: Zhou
authors.initials: Z
authors.lastname: Wu
authors.forename: Hong Mei
authors.initials: HM
authors.lastname: Ma
authors.forename: Toshio
authors.initials: T
authors.lastname: Kukita
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Nakanishi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakanishi
mesh_terms: D000818:Animals; D001169:Arthritis, Experimental / Q000276:immunology / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D001862:Bone Resorption / Q000276:immunology / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D002454:Cell Differentiation / Q000276:immunology*; D002478:Cells, Cultured; D015232:Dinoprostone / Q000378:metabolism; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000276:immunology*; D005260:Female; D006131:Growth Inhibitors / Q000008:administration & dosage* / Q000502:physiology*; D018960:Hyaluronan Receptors / Q000096:biosynthesis; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis; D008081:Liposomes; D010010:Osteoclasts / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D010718:Phosphatidylserines / Q000008:administration & dosage* / Q000502:physiology*; D053245:RANK Ligand / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D051381:Rats; D011917:Rats, Inbred Lew; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D013234:Stem Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism
chemical_list: D006131:Growth Inhibitors; D018960:Hyaluronan Receptors; D008081:Liposomes; D010718:Phosphatidylserines; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D053773:Transforming Growth Factor beta1; D018799:Intercellular Adhesion Molecule-1; D015232:Dinoprostone