The Inhibitory Effect And Mechanism Of PPD On Inflammatory Osteolysis

Purpose: Inflammation-related osteolysis is a kind of osteolysis which caused by inflammation with high incidence.Bacterial inflammation such as acute/chronic osteomyelitis or aseptic inflammation caused by internal plants played a critical part on the mechanism of osteolysis.However,it is a challenge for orthopaedic surgeons to overcome.The most important factor of the occurrence and development of inflammation-related osteolysis is the activation of osteoclasts caused by inflammation microenvironment,which leads to the imbalance of bone metabolism.Inhibiting osteoclast activation which means to remodel bone homeostasis is one of the important strategies for the treatment of inflammation-related osteolysis.This project intends to confirm that 20(S)-protopanaxadiol(PPD)as an AMPK activator could inhibit osteolysis in vivo and in vitro.Methods: Murine calvarial osteolysis models induced by LPS and Ti particles with PPD intervention were established which imitated the microenvironment of bacterial and aseptic inflammation,respectively.3D reconstruction and bone metrology analysis were carried out by micro-CT.Bone destruction was analyzed by HE staining and Tartrate resistant acid phosphatase(TRAP)staining.Bone marrow-derived macrophages were induced in to osteoclasts to imitate the pathological progress of osteolysis.Osteoclast differentiation of bone marrow-derived macrophages was analyzed by TRAP staining.The function of osteoclasts was analyzed by F-atin staining and resorption pit formation assay.WB and luciferase reporter gene assay were performed to point out the potential signal pahway.Further,AMPK inhibitorDorsomorphin(Compound C)was added to analyze the differentiation and function of osteoclasts.Results: In vivo,bone morphometric analysis and morphological analysis confirmed that PPD could inhibit the osteolysis progress effectively in two animal models.In vitro,TRAP staining showed that PPD could inhibit the osteoclast differentiation of bone marrowderived macrophages mediated by RANKL.F-actin formation and bone resorption of osteoclast were inhibited after PPD treated.Further,the inhibitory effect of PPD on osteolysis might be related to the inhabitation of MAPK and NF-?B by WB and luciferase reporter gene assay.On the other hand,Compound C can reverse the inhibitory effect of PPD on osteolysis.Conclusion: The results showed that PPD could inhibit the osteoclasts differentiation of bone marrow-derived macrophages and the function of osteoclasts by activating AMPK and inhibiting MAPK and NF-?B.Thus,PPD might be a potential treatment of inflammation-related osteolysis.