Melatonin at pharmacological concentrations suppresses osteoclastogenesis via the attenuation of intracellular ROS

• Published in: Osteoporosis international 2017-12, Vol.28 (12), p.3325-3337
• Main Authors: Zhou, L., Chen, X., Yan, J., Li, M., Liu, T., Zhu, C., Pan, G., Guo, Q., Yang, H., Pei, M., He, F.
• Format: Article
• Language: English
• Subjects: Acid phosphatase (tartrate-resistant); Age; Animals; Bone growth; Bone marrow; Bone Marrow Cells - drug effects; Bone resorption; Cell Differentiation - drug effects; Cell Proliferation - drug effects; Cells, Cultured; Dose-Response Relationship, Drug; Endocrinology; Gene expression; Hydrogen peroxide; Hydrogen Peroxide - pharmacology; Lymphocytes B; Male; Medicine; Medicine & Public Health; Melatonin; Melatonin - administration & dosage; Melatonin - antagonists & inhibitors; Melatonin - pharmacology; Mice, Inbred C57BL; Monocytes; NF-kappa B - antagonists & inhibitors; NF-kappa B - metabolism; NF-κB protein; Original Article; Orthopedics; Osteoblastogenesis; Osteoclastogenesis; Osteoclasts; Osteoclasts - drug effects; Osteogenesis; Osteogenesis - drug effects; Osteogenesis - physiology; Osteoporosis; Physiology; Reactive oxygen species; Reactive Oxygen Species - antagonists & inhibitors; Reactive Oxygen Species - metabolism; Rheumatology; Rodents; Signal transduction; Signal Transduction - physiology; SIRT1 protein; Sirtuin 1 - physiology
• ISSN: 0937-941X; 1433-2965
• DOI: 10.1007/s00198-017-4127-8

Summary Osteoporosis is linked to age-related decline of melatonin production; however, the direct effects of melatonin on osteoclastogenesis remain unknown. Our study demonstrates that melatonin at pharmacological concentrations, rather than at physiological concentrations, significantly inhibits osteoclastogenesis. Melatonin-mediated anti-osteoclastogenesis involves a reactive oxygen species (ROS)-mediated but not a silent information regulator type 1 (SIRT1)-independent pathway. Introduction Osteoporosis is a bone disorder linked to impaired bone formation and excessive bone resorption. Melatonin has been suggested to treat osteoporosis due to its beneficial actions on osteoblast differentiation. However, the direct effects of melatonin on osteoclastogenesis in bone marrow monocytes (BMMs) remain unknown. This study was to investigate whether melatonin at either physiological or pharmacological concentrations could affect osteoclast differentiation. Methods Primary BMMs were isolated from the femurs and tibias of C57BL/6 mice and were induced toward multinucleated osteoclasts, in the presence of melatonin at either physiological (0.01 to 10 nM) or pharmacological (1 to 100 μM) concentrations. Tartrate-resistant acid phosphatase (TRAP) staining was used to label multinucleated osteoclasts and the levels of osteoclast-specific genes were evaluated. To further explore the underlying mechanisms, the roles of silent information regulator type 1 (SIRT1) and reactive oxygen species (ROS) were evaluated. Results We found that melatonin at pharmacological concentrations, rather than at physiological concentrations, significantly inhibited osteoclast formation in a dose-dependent manner. The number of TRAP-positive cells and the gene expression of osteoclast-specific markers were significantly downregulated in melatonin-treated BMMs. The melatonin-mediated repression of osteoclast differentiation involved the inhibition of the nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) signaling pathway. The treatment with SIRT1 inhibitors did not affect osteoclast differentiation but, when supplemented with exogenous hydrogen peroxide, a partial rescue of melatonin-suppressed osteoclastogenesis was observed. Conclusion Melatonin at pharmacological doses directly inhibited osteoclastogenesis of BMMs by a ROS-mediated but not a SIRT1-independent pathway.