The Recombinant Protein ephB4-Fc Changes the Ti-Particle Mediated Imbalance of OPG/RANKL Via ephrinB2/ephB4 Signaling Pathway and Inhibits the Release of Pro-Inflammatory Factors in vivo

Background: Aseptic loosening caused by wear particles is a common complications after total hip arthroplasty. We investigated the effect of the recombinant protein ephB4-Fc (erythropoietin-producing human hepatocellular receptor 4) on wear particle-mediated inflammatory response. Methods: In vitro, ephrinB2 expression was analyzed using siRNA-NFATc1 (nuclear factor of activated T-cells 1) and siRNA-c-Fos. Additionally, we used Tartrate-resistant acid phosphatase (TRAP) staining, bone pit resorption, Enzyme-linked immunosorbent assay (ELISA) as well as ephrinB2 over-expression and knockdown experiments to verify the effect of ephB4-Fc on osteoclast differentiation and function. In vivo, a mouse skull model was constructed to test whether that the ephB4-Fc inhibits osteolysis and inhibits inflammation by micro-CT, H&E staining, immunohistochemistry, and immunofluorescence. Finding: The gene expression of ephrinB2 was regulated by c-Fos/NFATc1. Titanium wear particles activated this signaling pathway to promoted expression of the ephrinB2 gene. However, ephrinB2 protein can be activated by osteoblast membrane receptor ephB4 to inhibit osteoclast differentiation. In vivo experiments we found that ephB4 could regulate Ti-particle mediated imbalance of OPG/RANKL, and the most important finding was that ephB4 relieved the release of pro-inflammatory factors. Interpretation: The ephB4-Fc inhibits wear particle-mediated osteolysis and inflammatory response through the ephrinB2/EphB4 bidirectional signaling pathway, and ephrinB2 ligand is expected to become a new clinical drug therapeutic target. Funding: The present study was supported by grants from the National Natural Science Foundation of China (grant nos., 81572158, 81772361 and 81572116). Declaration of Interest: The authors declare no conflict of interests. Ethical Approval: All animal procedures were approved by the Animal Hospital affiliated to Shanghai Jiao Tong University. In addition, Periprosthetic interface tissues were gained at the time of revision surgery. This study was approved by the local Ethics Committee.