STAT3/IL-6 dependent induction of inflammatory response in osteoblast and osteoclast formation in nanoscale wear particle-induced aseptic prosthesis loosening

Background : Aseptic loosening is the main reason for surgical revision after arthroplasty. Although a series of mechanisms have been explored, a specific therapeutic target is still desired. In the present study, we explored the role of the signal transducer and activator of the transcription (STAT)/interleukin-6 (IL-6) pathway in the induction of the inflammatory response in osteoblast and osteoclast formation during aseptic prosthesis loosening. Methods : The expression of activated STAT3 was examined in osteoblasts treated with TiAl6V4 nanoparticles (TiPs) from materials used in prosthetics and specimens from particle-induced osteolysis (PIO) animal models. Inflammatory responses associated with the IL-6 family in osteoblasts were identified by Quantitative Real-time PCR. A mimicking coculture system was used to directly determine the number of activated osteoclasts in vitro , and immunohistochemical staining with tartrate-resistant acid phosphatase (TRAP) was used in vivo . CP690,550, an inhibitor of STAT3, was administered to examine the effect of STAT3 on the inflammatory response and osteoclast formation. Results : STAT3 was activated in both nanoparticle-treated osteoblasts and PIO model animals. On the one hand, the activation of STAT3 mediated nanoparticle-induced IL-6-dependent inflammatory responses in osteoblasts. On the other hand, the activation of STAT3 induced receptor activator of nuclear factor kappa B ligand (RANKL) production and stimulated osteoclast formation. The application of the STAT3 inhibitor CP690,550 reduced the production of the IL-6 family and the formation of osteoclasts both in vitro and in vivo . Conclusion : STAT3 mediated inflammation-related signalling and osteoclast activation in nanoscale wear particle-induced aseptic loosening. Inhibition of STAT3 by tofacitinib may be a potential treatment for aseptic loosening. Our study demonstrated wear particles, which are generated by the abrasion of implanted prostheses, could induced STAT3 activation in osteoblasts. And further, inflammatory responses and RANKL expression would activate osteoclasts and cause osteolysis.