Amyloid-β peptide treatment reverses bone loss in the mandibular condyle via Wnt signalling pathway.

Objective: To explore the effect of amyloid-β peptide (Aβ) on mandibular condyle to develop a new treatment for postmenopausal women with Temporomandibular joint osteoarthritis.

Methods: A murine bone loss model was established by ovariectomy. Microstructure parameters of the condyle were measured by microcomputed tomography before and after intraperitoneal injection with Aβ. Flow cytometry, Alizarin red staining, RT-qPCR assays, FITC/PI staining, Oil Red O staining and western blotting were used to evaluate the effect of Aβ on the osteogenic differentiation of mouse bone marrow stromal stem cells (mBMSCs).

Results: In vivo, condylar microstructure parameters increased. Serum osteoprotegerin and procollagen type 1 N propeptide increased in a dose-dependent manner after the injection of Aβ, which were opposite the changes observed in c-terminal telopeptides of type I collagen, tumor necrosis factor-α and the high serum level of leptin. In vitro, Aβ promoted calcium nodule formation in the cells. The expression of ALP, Runx2, osteorix and osteocalcin increased significantly. The expression of mRNAs related to the Wnt signaling pathway was significantly upregulated, which could be blocked by DKK1.

Conclusion: Aβ can reverse bone loss in the mandibular condyle in ovariectomized mice through promoting the osteogenic differentiation of mBMSCs via the Wnt pathway.