Inhibitory Effects Of Adenovirus-Mediated SiRNA Targeting P38 On Titanium Particle-Induced Osteoclast Formation And Osteolysis

ObjectiveTo investigate the effect of mitogen-activated protein kinase signal pathway on osteoclast formation induced by Ti particle, then constructed an adenovirus mediated siRNA to knock down the expression of p38, in order to evaluate the effect and possible mechanism of sip38 on Ti particle induced osteoclast formation and osteolysis.Methods1. Bone marrow macrophages were treated with or without Ti particle (0.1mg/ml) in vitro, the numbers of osteoclasts were measured by the tartrate-resistant acid phosphatase (TRAP) staining. The expressions of TRAP protein and the phosphorylation levels of MAPK signal pathway proteins were determined by Western Blot.2. Then an adenovirus-mediated RNA interference targeting p38 was employed to knock down the expression of p38 and the numbers of osteo-clasts were determined by TRAP staining, the expression of osteoclast specific protein TRAP was measured using Western Blot and Immuno-fluorescent. Semi-quantitative RT-PCR was conducted to detect the gene expression of NFATc1 and c-fos.3. A mouse calvaria osteolysis model was conducted to determine the effect of Ti particle exposure in vivo. H&E staining was conducted to assess the erosion of bone. The numbers of osteoclasts were determined by Histological TRAP staining and immunohistological staining. Results1. Ti particles could promote the osteoclast formation and differen-tiation via p38 MAPK and INK signal pathway in vitro.2. Adenovirus-mediated p38 siRNA has a significant inhibition effect on the formation of osteoclast in vitro, including decreasing the protein expression of TRAP and the gene expression of NFATc1 and c-fos.3. The mouse calvaria osteolysis model was conducted successfully. We revealed that adenovirus-mediated siRNA targeting p38 inhibited the osteoclast formation and osteolysis induced by Ti particles in vivo study.ConclusionIn this study, we revealed that ti particles could promote osteoclast formation via p38 MAPK signal pathway. Adenovirus-mediated p38 siRNA was able to suppress osteoclast formation induced by Ti particle in the presence of RANKL via down-regulation the expression of c-fos and NFATc1. Locally injection of adenovirus-mediated p38 siRNA may be an effective method for the treatment of periprosthetic osteolysis associated with wear debris.