title: Enhanced inhibitory effects of a novel CpG motif on osteoclast differentiation via TREM-2 down-regulation.
abstract: Recognition of oligodeoxynucleotides containing CpG motifs (CpG-ODNs) by toll-like receptor 9 (TLR9) inhibits RANKL-induced osteoclastogenesis from precursors. This inhibitory effect suggests the possibility of using this strategy to block pathological bone loss. However, the enhancing effect of CpG-ODNs on OC formation from RANKL-primed pre-osteoclasts (pOCs) has hampered their clinical use. In this report, we developed a CpG-KSK13 oligonucleotide with an alternative CpG motif, and tested its effect on osteoclastogenesis in comparison with previously used murine CpG motif (CpG-1826) or human CpG motif (CpG-2006) oligonucleotides. Murine CpG-1826 inhibited RANKL-induced OC formation from BMMs but not from RANKL-primed pOCs, while CpG-KSK13 treatment strongly inhibited OC formation from both BMM and primed pOC cells. CpG-KSK13 also showed a potent inhibitory effect on human OC differentiation using peripheral blood mononuclear cells (PBMCs), which was in contrast to the species-specific response of murine CpG-1826 or human CpG-2006. Moreover, CpG-KSK13 effectively inhibited NFATc1 activity, but not NF-kappaB or AP-1 activity, and decreased TREM-2 promoter activity and subsequent surface expression of the TREM-2 protein induced by M-CSF and RANKL. These results demonstrate that the recognition of CpG-KSK13 via TLR9 inhibits osteoclastogenesis by down-regulating TREM-2 expression. Thus, our findings provide evidence for the potential use of CpG-KSK13 as an anti-osteoclastogenic agent for human and for pre-clinical animals.
authors.affiliation: Institute of Basic Medical Science, Wonju College of Medicine, Yonsei University, Wonju 220-710, South Korea.
authors.forename: Jae-Ho
authors.initials: JH
authors.lastname: Chang
authors.forename: Eun-Ju
authors.initials: EJ
authors.lastname: Chang
authors.forename: Hong-Hee
authors.initials: HH
authors.lastname: Kim
authors.forename: Soo-Ki
authors.initials: SK
authors.lastname: Kim
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D018899:CpG Islands; D015536:Down-Regulation; D006801:Humans; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D050778:NFATC Transcription Factors / Q000037:antagonists & inhibitors; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology*; D010010:Osteoclasts / Q000187:drug effects* / Q000378:metabolism; D053245:RANK Ligand / Q000378:metabolism; D011971:Receptors, Immunologic / Q000378:metabolism*; D051217:Toll-Like Receptor 9 / Q000819:agonists
chemical_list: C408982:CPG-oligonucleotide; C544079:CpG-KSK13; D008562:Membrane Glycoproteins; D050778:NFATC Transcription Factors; C494005:Nfatc1 protein, mouse; D009838:Oligodeoxyribonucleotides; D053245:RANK Ligand; D011971:Receptors, Immunologic; C498715:TREM2 protein, human; D051217:Toll-Like Receptor 9