OBJECTIVEThis work aims to examine the effects of paeonol treatment on the ability of bone marrow-derived macrophage (BMM) to excrete inflammatory factors and to differentiate into osteoclasts upon induction with Porphyromonas gingivalis (P. gingivalis). This work also aims to investigate the underlying mechanisms of these abilities.

METHODSBMM culture was treated with different paeonol concentrations at for 1 h and then stimulated with P. gingivalis for 24 h before programmed death-ligand 1 (PD-L1) was quantified with flow cytometry. Tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 were detected by enzyme-linked immunosorbent assay (ELISA). The BMM culture was treated with the receptor activator for nuclear factor-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF), and then with paeonol for 1 h prior to induction with P. gingivalis. Then, osteoclast formation was assessed using tartrate resistant acid phosphatase (TRAP) staining. The osteoclast-related proteins TRAP and receptor activator of nuclear factor-κB (RANK) were quantified by Western blotting.

RESULTSPaeonol was nontoxic to BMM within a range of 10-50 μmol·L⁻¹. Flow cytometry showed that paeonol inhibited PD-L1 expression in P. gingivalis-induced BMM in a dose-dependent manner. ELISA indicated that paeonol dose-dependently inhibited the excretion of TNF-α, IL-1β, and IL-6 by P. gingivalis-induced BMM (P<0.01). TRAP staining revealed that paenol treatment inhibited the differentiation of P. gingivalis-induced BMM into osteoclasts. Western blot results suggested that paeonol decreased the expression of TRAP and RANK in BMM.

CONCLUSIONSPaeonol dose-dependently inhibited the excretion of the inflammatory factors TNF-α, IL-1β, and IL-6 by P. gingivalis-induced BMM in a dose-dependent manner. Moreover, paenol treatment prevented the differentiation of P. gingivalis-induced BMM differentiation into osteoclasts.
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