Effect of active fraction of Polyrhachis vicina Rogers on LPS-induced inflammatory bone loss in mice

Objective: To explore the effect of active fraction of Polyrhachis vicina Rogers(AFPR)on lipopoly-saccharide (LPS)-induced inflammatory bone loss in mice.Methods: Twenty-four male C57BL/6J mice with 6 mice in each group were randomly divided into sham group, model group (AFPR 0 g/kg) and AFPR treatment group(4 g/kg, 8 g/kg).The mice were injected intraperitoneally with LPS solution(5 mg/kg)on day 1 and day 4, respectively, and the inflammatory bone loss models were established after 7 days of feeding.Micro-CT scanning and hematoxylin-eosin (HE) staining were used to analyze the changes of tibial bone histomorphology and relat-ed parameters; tartrate-resistant acid phosphatase(TRAcP)staining was used to analyze the changes of osteoclast number in the tibial growth plate region of mice; nuclear factor of activated T cells 1 (NFATc1) and cathepsin K(CTSK) staining were used to analyze the changes of osteoclast activity; HE staining was used to observe the changes of liver and kidney tissues in mice.In addition, the effect of AFPR on osteoclast differentiation was in-vestigated by TRAcP staining and the effect of AFPR on osteoblast activity was investigated by alkaline phosphatase (ALP) staining and alizarin red S (ARD)staining in vitro.Results: Compared with sham group, the trabecular bone of tibia in the AFPR 0 g/kg group was significantly damaged, the number of osteoclasts significantly increased(P< 0.001), and the expressions of osteo-clast-specific factors NFATc1 and CTSK were up-regulated.Compared with AFPR 0 g/kg group, different doses of AFPR could effectively increase the thickness and number of bone trabeculae in bone tissue of mice, and also inhibit the activity of osteoclasts and the expression level of specific factors(P< 0.001)in a dose-dependent man-ner. In vitro experiments, compared with AFPR 0 μg/mL group, AFPR could inhibit osteoclast differentiation ef-fectively, but had no effect on osteoblast activity.Conclusion: AFPR has a certain protective effect on LPS-in-duced systemic inflammatory bone loss in mice, and may be related to the inhibition of osteoclast activity.