Fig. 2

Concentrations of (a) TNF-α, (b) IL-6, and (c) IL-10 in culture media after exposure to UHMWPE particles, metformin (5 mM), and different concentrations of AICAR (0.05, 0.5, or 5 mM) to activate AMPK. d Western blot results for phosphorylated AMPK (p-AMPK) and total AMPK (t-AMPK) in the different treatment groups. (Cropped gels/blots are used here, and the full-length gels and blots are shown in Additional file 1: Figure S4.) Concentrations of (e) TNF-α, (f) IL-6, and (g) IL-10 in culture media after exposure to UHMWPE particles, metformin (5 mM), and different concentrations of Compound C (0.01, 0.1, or 1 μM) to block AMPK. h Western blot results for phosphorylated AMPK (p-AMPK) and total AMPK (t-AMPK) in the different treatment groups. (Cropped gels/blots are used here, and the full-length gels and blots are shown in Additional file 1: Figure S4.) i Relative ratio of pAMPK/AMPK. j Number of osteoclasts per well in different groups. k Micro-CT scans of mouse calvaria in metformin-treated group and metformin plus compound C group. l BMD, BMC, BV/TV of both groups. Data represent the means ± SD. NC, negative control (no treatment); PC, positive control (treatment with UHMWPE particles only), C.C, Compound C. ***P < 0.001; **P < 0.01; *P < 0.05