Role of autocrine osteopontin in promoting multiple functions of murine Nf1+/-osteoclast

Abstract

Objective To detect the osteopontin （OPN） autocrine function of the osteoclasts in neurofibromatosis type 1 heterozygote （Nfl＋/-） and wild type （Nfl＋/＋） mice. Test the osteoclasts function of neurofibromatosis type 1 heterozygote （Nfl＋/-） and wild type （Nfl＋/＋） mice with exogenous neutralizing OPN antibody, analysis the role of autocrine OPN in the hyperfunction of osteoclast in neurofibromatosis type 1. Methods Culture the low density bone marrow cells from Nfl heterozygote （Nfl＋/-） and wild type （Nfl＋/＋） mice （ 4-6 weeks old ） with macrophage colony-stimulating factor （M-CSF） and receptor activator of NF-KB lig-and（RANKL）, Measure the OPN concentration in osteoclast culture superenant with ELISA. Culture the low density bone marrow ceils from Nfl ＋/- and Nfl ＋/＋ mice with or without exogenous neutralizing antibody for OPN. The function of osteoclasts and os-teoclast progenitors in formation, migration, adhesion, and bone absorption were tested. Results A significantly higher concen- tration of OPN was detected in the Nfl ＋/- osteoclast cuhure media as compared to that of wild type. In control, Osteoclast func-tions, including migration, adhesion, and bone resorption of Nfl＋/-were higher than that of wild type. Addition OPN neutralizing antibody to the Nfl＋/- OCL significantly reduced OCL formation. Neutralizing OPN antibody diminished both wild type and Nfl＋ /- OCL adhensiontion, Anti-OPN minimized OCL migration in both wild type and Nfl＋/- OCL cultures as measured by the tran- swell assays. Neutralizing OPN antibody diminished both wild type and Nfl＋/- OCL pit formation,P〉0.05 for comparing Nfl＋/- vs. wild type OCLs with anti-OPN antibody. Conclusion The hyperfunction of osteoclast in Nfl heterozygote is related with au- tocrine osteopontin, inhibition of OPN may be an effective treatment for bone destruction of neurofibromatosis type 1. Key words: Neurofibromatosis 1; Osteopontin; Osteoclasts; Mice