Pseurotin A Inhibits Osteoclastogenesis and Prevents Ovariectomized-Induced Bone Loss by Suppressing Reactive Oxygen Species

Vinpocetine inhibits RANKL-induced osteoclastogenesis and attenuates ovariectomy-induced bone loss

Osteoporosis is a result of impaired bone formation and/or excessive bone resorption. Osteoclasts are the only cells in the body that have a bone resorption function. Inhibiting osteoclast activity and differentiation is a way to treat osteoporosis. The current pharmacological treatment for osteoporosis has many shortcomings, and more effective treatments are needed. Vinpocetine (Vinp), a derivative of the alkaloid vincamine, has been used to treat cerebrovascular disorders and cognitive impairment for a long time. Vinp inhibits mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB)-dependent inflammatory responses and oxidative damage in which osteoclasts are often involved. However, the effects of Vinp on the regulation of osteoclast activity remain unknown. In this study, we found that Vinp significantly inhibited receptor activator of NF-κB ligand (RANKL)-induced osteoclast and F-actin formation and decreased osteoclastic bone resorption in vitro. Vinp also suppressed the expression of osteoclast-specific genes, including NFATc1, c-Fos, tartrate-resistant acid phosphatase (TRAP), matrix metalloproteinase-9 (MMP-9), and cathepsin K (CTSK) at both the mRNA and protein levels. Vinp reduced activation of NF-κB, MAPK, and AKT signaling during osteoclastogenesis and prevented the production of reactive oxygen species with increased nuclear factor erythroid 2-related factor 2, heme oxygenase 1, and NAD(P)H:quinone acceptor oxidoreductase 1 expression. Animal experiments consistently demonstrated that Vinp treatment significantly attenuated ovariectomy-induced bone loss with a decrease in the osteoclast number and decreases in serum levels of RANKL, TRAP, interleukin-1β, and tumor necrosis factor-alpha, as well as increased serum levels of osteoprotegerin. Taken together, our findings reveal that Vinp may be a potential pharmacological choice for preventing and treating osteoporosis.

Inhibitory effects of ChondroT and its constituent herbs on RANKL-induced osteoclastogenesis

Background

ChondroT is a complex herbal medicine consisting of water extracts of Ostericum koreanum (Maxim.) Kitag., Lonicera japonica Thunb., Angelica gigas Nakai, Clematis manshurica Rupr., and Phellodendron amurense Rupr. (6:4:4:4:3). Previous studies have reported that ChondroT possesses chondroprotective and anti-inflammatory, anti-osteoarthritic, and anti-hyperuricemic activities. The study is aim to demonstrate the effects of ChondroT and its five constituent herbs on receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis and the underlying mechanisms.

Methods

Osteoclastogenesis was identified in bone marrow-derived macrophages (BMDMs) by tartrate-resistant acid phosphatase (TRAP) staining assay, actin ring formation assay and the bone resorption assay. For the molecular mechanisms, activation of RANKL-induced NF-κB and MAPK signaling pathways and the expression levels of osteoclast-specific proteins were investigated by Western blotting. Cell viability was assessed by MTT assay. Actin ring formation and NF-κB translocation were evaluated by immunostaining.

Results

ChondroT and each of its constituent herbs significantly suppressed osteoclast differentiation dose dependently, and decreased actin ring formation as well as bone-resorbing capacity. Mechanistically, ChondroT and its constituent herbs downregulated the expressional levels of osteoclast-specific proteins such as NFATc1, c-Fos, Cathepsin K, and matrix metalloproteinase 9 (MMP9) by suppressing NF-κB translocation to nucleus and MAPKs phosphorylation at different levels. Compared to its five constituent herbs, ChondroT exhibited the best inhibitory efficiency against osteoclastogenesis.

Conclusions

Taken together, ChondroT has anti-osteoclastogenesis properties by inhibiting NF-κB and MAPKs pathways. It could be considered as a potential therapeutic candidate for the treatment of osteoclast-related bone diseases.

Loureirin B suppresses RANKL-induced osteoclastogenesis and ovariectomized osteoporosis via attenuating NFATc1 and ROS activities

Rationale: Osteoporosis is a severe bone disorder that is a threat to our aging population. Excessive osteoclast formation and bone resorption lead to changes in trabecular bone volume and architecture, leaving the bones vulnerable to fracture. Therapeutic approaches of inhibiting osteoclastogenesis and bone resorption have been proven to be an efficient approach to prevent osteoporosis. In our study, we have demonstrated for the first time that Loureirin B (LrB) inhibits ovariectomized osteoporosis and explored its underlying mechanisms of action in vitro. Methods: We examined the effects of LrB on RANKL-induced osteoclast differentiation and bone resorption, and its impacts on RANKL-induced NFATc1 activation, calcium oscillations and reactive oxygen species (ROS) production in osteoclasts in vitro. We assessed the in vivo efficacy of LrB using an ovariectomy (OVX)-induced osteoporosis model, which was analyzed using micro-computed tomography (micro-CT) and bone histomorphometry. Results: We found that LrB represses osteoclastogenesis, bone resorption, F-actin belts formation, osteoclast specific gene expressions, ROS activity and calcium oscillations through preventing NFATc1 translocation and expression as well as affecting MAPK-NFAT signaling pathways in vitro. Our in vivo study indicated that LrB prevents OVX-induced osteoporosis and preserves bone volume by repressing osteoclast activity and function. Conclusions: Our findings confirm that LrB can attenuate osteoclast formation and OVX-induced osteoporosis. This novel and exciting discovery could pave the way for the development of LrB as a potential therapeutic treatment for osteoporosis.