FcRγ mediates bone destruction and osteoporosis, but not inflammation in hTNFtg mice. (A) Osteoclastogenesis of hTNFtg BMMs stimulated with RANKL (1 or 5 ng/ml). ∗, P < 0.05. (B) Flow-cytometric analysis of PIRs' expression on the WT (dotted line) and hTNFtg (solid line) BMMs. (C) Expressions of NFATc1 and Ig-like receptors in hTNFtg BMMs (immunoblot analysis). (D) RANKL-induced osteoclastogenesis of WT, hTNFtg, FcRγ−/−, and hTNFtg/FcRγ−/− BMMs. ∗, P < 0.05. (E) Expression of NFATc1 in WT, hTNFtg, FcRγ−/−, and hTNFtg/FcRγ−/− BMMs (immunoblot analysis). (F) (Upper) Histological analysis of ankle joints (H&E). (Lower) Magnified view of the rectangular area. (G) Paw thickness of WT, hTNFtg, and hTNFtg/FcRγ−/− mice. n.s., not significant. (H–J) Arthritis score (H), histological score (I), and fold increase (J) in the number of osteoclasts in the ankles of WT, hTNFtg, and hTNFtg/FcRγ−/− mice. n.s., not significant; ∗, P < 0.05; ∗∗, P < 0.01. (K) Histological analysis of proximal tibiae of WT, hTNFtg, and hTNFtg/FcRγ−/− mice (TRAP and Toluidine blue staining). (L–N) BV/TV (L), number of osteoclasts per bone surface (N.Oc/BS) (M), and BMD (N) of tibiae of WT, hTNFtg, and hTNFtg/FcRγ−/− mice. ∗, P < 0.05.