FIGURE 6.

LPS from P. gingivalis and the TLR2 agonist Pam2 regulates bone resorption and osteoclast formation differently in parietal bones, periosteal/endosteal bone cell, and bone marrow cell cultures primed by RANKL (RL). A, RANKL (10 ng/ml)-stimulated ⁴⁵Ca release from neonatal mouse parietal bones in organ culture was not affected by LPS P. gingivalis (10 μg/ml) or Pam2 (10 ng/ml). B–E, RL (10 ng/ml) stimulation of tartrate-resistant acid phosphatase-positive, multinucleated osteoclasts (TRAP⁺MuOCL), and mRNA expression of Ctsk and Acp5 in periosteal/endosteal cell cultures from mouse parietal bone were not affected by co-treatment with LPS P. gingivalis (P.g., 10 μg/ml) or Pam2 (10 ng/ml). F–H, increased formation of TRAP⁺ multinucleated osteoclasts and mRNA expression of Ctsk and Acp5 in M-CSF (30 ng/ml)- and RL (4 ng/ml)-stimulated mouse bone marrow cell cultures were abolished by co-treatment with LPS P. gingivalis and Pam2. I–M, LPS P. gingivalis (10 μg/ml) and Pam2 (10 ng/ml) increased formation of TRAP⁺ multinucleated osteoclasts and mRNA expression of Acp5, Ctsk and Tnfsf11 in periosteal/endosteal cell cultures from mouse parietal bone. N, the stimulatory effect by LPS P. gingivalis and Pam2 on osteoclast formation in periosteal/endosteal cell cultures was abolished by adding OPG (300 ng/ml) to the culture medium. ***, p < 0.001 compared with unstimulated controls. Data are the means of six-seven observations, and S.E. is given as vertical bars.