title: Inhibition of titanium particle-induced inflammatory osteolysis through inactivation of cannabinoid receptor 2 by AM630.
abstract: Wear particle could induce inflammatory osteolysis and is the primary pathological factor for aseptic loosening. Although it is known that cannabinoid receptor 2 (CB2) inhibits osteoclast differentiation, the effect on inflammatory osteolysis induced by wear particles remains unclear. This study examined the effect of CB2 in the regulation of osteoclast differentiation in a murine macrophage cell line (RAW264.7), which has been shown to be stimulated by titanium (Ti) particles and receptor activator of the NF-kappaB ligand (RANKL). Results showed that CB2 expression in RAW cells cultured with Ti particles and RANKL. CB2 inactivation by AM630, a CB2 selective antagonist, effectively inhibited osteoclastogenesis in the differentiation medium system. AM630 treatment (> or =100 nM) significantly reduced the number of tartrate-resistant acid phosphatase-positive cells when compared with the control. Real-time reverse transcription polymerase chain reaction analysis revealed that AM630 (100 nM) inhibited mRNA expression of RANK and cathepsin K in RAW cells stimulated by Ti particles and RANKL. Moreover, enzyme-linked immunosorbent assay showed that AM630 (100 nM) reduced protein expression of interleukin-1beta and tumor necrosis factor-alpha in RAW cells cultured with Ti particles. In addition, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide revealed that AM630 had no toxic effect on RAW cells. These results suggested that CB2 inactivation by AM630 could provide a promising therapeutic target for treating or preventing aseptic loosening.
authors.affiliation: Department of Orthopedics, The First Affiliated Hospital of Soochow University, Suzhou 215006, People's Republic of China.
authors.forename: D C
authors.initials: DC
authors.lastname: Geng
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Xu
authors.forename: H L
authors.initials: HL
authors.lastname: Yang
authors.forename: X S
authors.initials: XS
authors.lastname: Zhu
authors.forename: G M
authors.initials: GM
authors.lastname: Zhu
authors.forename: X B
authors.initials: XB
authors.lastname: Wang
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis; D005786:Gene Expression Regulation / Q000187:drug effects; D007211:Indoles / Q000494:pharmacology*; D007249:Inflammation / Q000139:chemically induced / Q000150:complications* / Q000517:prevention & control*; D018836:Inflammation Mediators / Q000378:metabolism; D051379:Mice; D008855:Microscopy, Electron, Scanning; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects; D010014:Osteolysis / Q000139:chemically induced / Q000150:complications* / Q000517:prevention & control*; D043885:Receptor, Cannabinoid, CB2 / Q000235:genetics / Q000378:metabolism*; D014025:Titanium / Q000633:toxicity*
chemical_list: D016207:Cytokines; D007211:Indoles; D018836:Inflammation Mediators; D043885:Receptor, Cannabinoid, CB2; D014025:Titanium; C094023:iodopravadoline