Xerophilusin B attenuates wear particle: associated osteolysis by inhibiting NF-κB signaling and restoring osteoblast-osteoclast coupling.

Periprosthetic osteolysis after total joint arthroplasty is the leading cause of aseptic loosening. Bone metabolic imbalance driven by aberrant NF-κB activation mediated by titanium wear particles is a central pathogenic mechanism. Available therapies have clear limitations, and the role and mechanism of Xerophilusin B (XB) in this setting have not been clarified. To evaluate the regulatory effects of XB on titanium wear particle-induced osteolysis and to define the key mechanism involved, with the aim of identifying a potential candidate for preventing and treating periprosthetic osteolysis. RAW264.7 osteoclast precursors and MC3T3-E1 osteoblasts were treated with XB at 0, 5, 10, or 20 µmol/L. Titanium wear particles were used to establish an in vitro model of bone metabolic imbalance. Cell viability and proliferation were assessed with CCK-8 and EdU staining. Osteoclast differentiation and function were evaluated by TRAP staining and a bone resorption pit assay. Osteoblast differentiation and mineralization were examined using ALP staining and Alizarin Red S staining. Western blotting was used to quantify bone-metabolism-related proteins and NF-κB pathway proteins. In vivo, 48 C57BL/6 mice were randomly assigned to the control group, Wear group, Intervention group, and Combination group (NF-κB activator). A calvarial osteolysis model was established. After 4 weeks of continuous intraperitoneal administration, histological staining, immunohistochemistry, ELISA, and Western blotting were performed to verify in vivo effects and mechanisms. XB at 10 µmol/L showed no detectable cytotoxicity and was used as the working concentration. Under titanium wear particle stimulation, XB reduced the number of TRAP-positive multinucleated osteoclasts by 56.79%, indicating marked inhibition of osteoclast differentiation and resorptive activity. In MC3T3-E1 cells, the ALP-positive staining area recovered to 87.82%, showing that XB counteracted particle-mediated suppression of osteogenic differentiation and mineralization. At the signaling level, XB blocked abnormal phosphorylation of IKKα/β and p65, restrained NF-κB activation, and modulated the expression of bone-metabolism-related proteins including TRAP, CTSK, Runx2, and OCN. In vivo, XB alleviated calvarial osteolysis-associated pathological injury, adjusted serum markers of bone resorption and formation, and showed no apparent hepatorenal toxicity at the experimental dose. An NF-κB pathway activator largely attenuated XB's osteoprotective effect. By inhibiting NF-κB signaling, XB bidirectionally regulates osteoclast-osteoblast function and bone metabolic homeostasis, effectively mitigating titanium wear particle-induced calvarial osteolysis.