Aminothiazoles inhibit osteoclastogenesis and PGE2 production in LPS‐stimulated co‐cultures of periodontal ligament and RAW 264.7 cells and RANKL‐mediated osteoclastogenesis and bone resorption in PBMCs

摘要

Inflammatory mediator prostaglandin E2 (PGE 2) contributes to bone resorption in several inflammatory conditions including periodontitis. The terminal enzyme, microsomal prostaglandin E synthase‐1 (mPGES‐1) regulating PGE 2 synthesis is a promising therapeutic target to reduce inflammatory bone loss. The aim of this study was to investigate effects of mPGES‐1 inhibitors, aminothiazoles TH‐848 and TH‐644, on PGE 2 production and osteoclastogenesis in co‐cultures of periodontal ligament (PDL) and osteoclast progenitor cells RAW 264.7, stimulated by lipopolysaccharide (LPS), and bone resorption in RANKL‐mediated peripheral blood mononuclear cells (PBMCs). PDL and RAW 264.7 cells were cultured separately or co‐cultured and treated with LPS alone or in combination with aminothiazoles. Multinucleated cells stained positively for tartrate‐resistant acid phosphatase (TRAP) were scored as osteoclast‐like cells. Levels of style="fixed-case">PGE 2, osteoprotegerin ( style="fixed-case">OPG) and interleukin‐6, as well as style="fixed-case">mRNA expression of style="fixed-case">mPGES‐1, style="fixed-case">OPG and style="fixed-case">RANKL were analysed in style="fixed-case">PDL cells. style="fixed-case">PBMCs were treated with style="fixed-case">RANKL alone or in combination with aminothiazoles. style="fixed-case">TRAP‐positive multinucleated cells were analysed and bone resorption was measured by the style="fixed-case">CTX‐I assay. Aminothiazoles reduced style="fixed-case">LPS‐stimulated osteoclast‐like cell formation both in co‐cultures and in style="fixed-case">RAW 264.7 cells. Additionally, aminothiazoles inhibited style="fixed-case">PGE 2 production in style="fixed-case">LPS‐stimulated cultures, but did not affect style="fixed-case">LPS‐induced style="fixed-case">mPGES‐1, style="fixed-case">OPG or style="fixed-case">RANKL style="fixed-case">mRNA expression in style="fixed-case">PDL cells. In style="fixed-case">PBMCs, inhibitors decreased both osteoclast differentiation and bone resorption. In conclusion, aminothiazoles reduced the formation of osteoclast‐like cells and decreased the production of style="fixed-case">PGE 2 in co‐cultures as well as single‐cell cultures. Furthermore, these compounds inhibited style="fixed-case">RANKL‐induced bone resorption and differentiation of style="fixed-case">PBMCs, suggesting these inhibitors for future treatment of inflammatory bone loss such as periodontitis.