Bone loss due to age and disuse contributes to osteoporosis and increases fracture risk. It has been hypothesized that such bone loss can be attenuated by modulation of the C–C chemokine receptor 2 (CCR2) and/or its ligands. The objectives of this study were to examine the effects of genetic elimination of CCR2 on cortical and trabecular bones in the mouse tibia and how bone loss was impacted following disuse and estrogen loss. Female CCR2 knockout (CCR2−/−) and wildtype mice underwent ovariectomy (OVX) or denervation of musculature adjacent to the tibia (DEN) to induce bone loss. Cortical and trabecular structural properties as well as mechanical properties (i.e., strength) of tibial bones were measured. Compared to wildtype mice, CCR2−/− mice had tibiae that were up to 9 % larger and stronger; these differences could be explained mainly by the 17 % greater body mass (P < 0.001) of CCR2−/− mice. The majority of the tibia’s structural and functional responses to OVX and DEN were similar regardless of the lack or presence of CCR2, indicating that CCR2 is not protective against bone loss per se. These findings indicate that while CCR2−/− mice do have larger and stronger bones than do wildtype mice, there is minimal evidence that CCR2 elimination provides protection against bone loss during disuse and estrogen loss.
Bibliographical noteFunding Information:
The authors thank Sarah Greising, Kristen Baltgalvis, and Greg Cochrane for their technical assistance. This work was supported by National Institutes of Health (NIH) Grants R01 AG031743 (DL and GW), K02 AGA036827 (DL), T32-AR07612 (SN), and T32-AG029796 (TM).
© 2014, Springer Science+Business Media New York.
- Bone remodeling
- Chemokine receptor
- Monocyte Chemoattractant Protein-1 (MCP-1)