Leukotriene B4 Loaded in Microspheres Inhibits Osteoclast Differentiation and Activation

Abstract

Abstract To investigate osteoclast formation in vivo and if leukotriene B4 (LTB4) loaded in microspheres (MS) could be used as a therapeutical strategy to promote a sustained delivery of the mediator and prevent osteoclast differentiation. Methods: In vivo, apical periodontitis was induced in mice to investigate osteoclast differentiation and signaling in absence of 5-lipoxygenase (5-LO). In vitro, LTB4-MS were prepared using an oil-in-water emulsion solvent extraction-evaporation process. Characterization and efficiency of LTB4 encapsulation were investigated. J774A.1 macrophages were cultured in the presence of monocyte colony-stimulating factor (M-CSF) and ligand for receptor activator of nuclear factor kappa B (RANKL) and then stimulated with LTB4-MS. Cytotoxicity, in vitro MS-LTB4 uptake, osteoclast formation and gene expression were measured. Results: We found that 5-LO negatively regulates osteoclastic formation in vivo during apical periodontitis development. In vitro, LTB4-MS were up-taken by macrophages and were not cytotoxic to the cells. LTB4-MS inhibited osteoclast formation and the synthesis of osteoclastogenic genes Acp5, Mmp9, Calcr and Ctsk. LTB4-MS inhibited differentiation of macrophages into an osteoclastic phenotype and cell activation under M-CSF and RANKL stimulus.