[Regulation of bone metabolism in osteoporosis : novel drugs for osteoporosis in development]

Postmenopausal osteoporosis: a bioinformatics-integrated experimental study the pathogenesis

Postmenopausal osteoporosis (PMOP) is a chronic bone metabolic disease, which often causes fractures and various complications, it causes a great social and economic burden, and it is urgent to use modern research techniques to elucidate the pathogenesis of PMOP. At the same time, because of the complex physiological and pathological interaction mechanism between osteoporosis and sarcopenia, the correlation research has become a hot topic. Ovary removal is a commonly used experimental method to study the endocrine system of female animals, and it is also the best animal model to study PMOP. In this study, the preparation of the ovariectomized rat was confirmed through the detection of vaginal smear, the level of bone formation markers, and the analysis of bone tissue morphology. Transcriptome sequencing was used to analyze the molecular mechanism of PMOP in ovariectomized rats, qRT-PCR was used to verify the key targets. Results of Micro-CT and scanning electron microscopy (SEM) showed that the trabecular structure was disorganized and the symptoms of osteoporosis appeared, this indicating that the ovariectomized rats model was successfully prepared. Transcriptional sequencing results of femur tissue showed that 452 differentially expressed genes (DEGs) were screened. Bioinformatics analysis results showed that the osteoporosis caused by ovariectomized rats was mainly related to muscle contraction, calcium signaling pathway, etc. Results of qRT-PCR were consistent with transcriptome analysis. These results reveal the pathogenesis of PMOP in ovariectomized rats and also offer a possibility for elucidating the relevance of action between PMOP and sarcopenia.

Molecular basis and therapeutic potential of myostatin on bone formation and metabolism in orthopedic disease

Myostatin, a member of the transforming growth factor-β (TGF-β) superfamily, is a key autocrine/paracrine inhibitor of skeletal muscle growth. Recently, researchers have postulated that myostatin is a negative regulator of bone formation and metabolism. Reportedly, myostatin is highly expressed in the fracture area, affecting the endochondral ossification process during the early stages of fracture healing. Furthermore, myostatin is highly expressed in the synovium of patients with rheumatoid arthritis (RA) and is an effective therapeutic target for interfering with osteoclast formation and joint destruction in RA. Thus, myostatin is a potent anti-osteogenic factor and a direct modulator of osteoclast differentiation. Evaluation of the molecular pathway revealed that myostatin can activate SMAD and mitogen-activated protein kinase signaling pathways, inhibiting the Wnt/β-catenin pathway to synergistically regulate muscle and bone growth and metabolism. In summary, inhibition of myostatin or the myostatin signaling pathway has therapeutic potential in the treatment of orthopedic diseases. This review focused on the effects of myostatin on bone formation and metabolism and discussed the potential therapeutic effects of inhibiting myostatin and its pathways in related orthopedic diseases.

Knockdown of LMX1B Suppressed Cell Apoptosis and Inflammatory Response in IL-1β-Induced Human Osteoarthritis Chondrocytes through NF-κB and NLRP3 Signal Pathway

Osteoarthritis (OA), a chronic degenerative joint disease, always occurred in the aging population. There is evidence suggests that chondrocytes' survival, inflammation, and apoptosis play critical roles in OA pathogenesis. LMX1B has been shown to be involved in antiosteogenic function in early patterning of the calvaria. However, the role and mechanism of LMX1B in OA is not unknown. The present study observed that LMX1B was highly expressed in OA patients compared with normal patients. Besides, we found that IL-1β increased LMX1B mRNA and protein expression in SW1353 and C28/I2 chondrocytes. LMX1B knockdown increased IL-1β-induced cell viability and proliferation and suppressed cell apoptosis and inflammation response, including IFN-γ, TNF-α, IL-6, prostaglandin E2 (PGE2), and NO both in SW1353 and C28/I2. Furthermore, LMX1B silence inhibited MMP-3 and MMP-13 expression both in SW1353 and C28/I2 cells. Also, the activation of the NF-κB and NLRP3 signaling pathway was suppressed in LMX1B silence cells by decreasing the p-p65 and NLRP3 protein expressions. Additionally, inhibition of NF-κB by PDTC suppressed NLRP3 expression. Moreover, NLRP3 overexpression reversed the effects of LMX1B silence on chondrocytes' survival, proliferation, apoptosis, and inflammation. Finally, we confirmed that LMX1B depletion had protective effects in OA rats in vivo.

Genkwanin Prevents Lipopolysaccharide-Induced Inflammatory Bone Destruction and Ovariectomy-Induced Bone Loss

Objectives

The first objective of this study was to probe the effects of genkwanin (GKA) on osteoclast. The second goal of this study was to study whether GKA can protect lipopolysaccharide (LPS) and ovariectomized (OVX) induced bone loss.

Materials and Methods

Various concentrations of GKA (1 and 10 mg/kg) were injected into mice. Different concentrations of GKA (1 and 5 μM) were used to detect the effects of GKA on osteoclast and osteoblast.

Key Findings

GKA attenuated the osteoclast differentiation promoted by RANKL and expression of marker genes containing c-fos, ctsk as well as bone resorption related gene Trap and to the suppression of MAPK signaling pathway. In addition, GKA induced BMMs cell apoptosis in vitro. Moreover, GKA prevented LPS-induced and ovariectomized-induced bone loss in mice.

Conclusion

Our research revealed that GKA had a potential to be an effective therapeutic agent for osteoclast-mediated osteoporosis.

SHIP1 Activator AQX-1125 Regulates Osteogenesis and Osteoclastogenesis Through PI3K/Akt and NF-κb Signaling

With the worldwide aging population, the prevalence of osteoporosis is on the rise, particularly the number of postmenopausal women with the condition. However, the various adverse side effects associated with the currently available treatment options underscore the need to develop novel therapies. In this study, we investigated the use of AQX-1125, a novel clinical-stage activator of inositol phosphatase-1 (SHIP1), in ovariectomized (OVX) mice, identifying a protective role. We then found that the effect was likely due to increased osteogenesis and mineralization and decreased osteoclastogenesis caused by AQX-1125 in a time- and dose-dependent manner. The effect against OVX-induced bone loss was identified to be SHIP1-dependent as pretreatment of BMSCs and BMMs with SHIP1 RNAi could greatly diminish the osteoprotective effects. Furthermore, SHIP1 RNAi administration in vivo induced significant bone loss and decreased bone mass. Mechanistically, AQX-1125 upregulated the expression level and activity of SHIP1, followed upregulating the phosphorylation levels of PI3K and Akt to promote osteoblast-related gene expressions, including Alp, cbfa1, Col1a1, and osteocalcin (OCN). NF-κB signaling was also inhibited through suppression of the phosphorylation of IκBα and P65 induced by RANKL, resulting in diminished osteoclastogenesis. Taken together, our results demonstrate that AQX-1125 may be a promising candidate for preventing and treating bone loss.

N-Butanol Extract of Modified You-Gui-Yin Attenuates Osteoclastogenesis and Ameliorates Osteoporosis by Inhibiting RANKL-Mediated NF-κB Signaling

Postmenopausal Osteoporosis (PMOP) is the most prevalent primary osteoporosis, attributable to an imbalance in osteoblast and osteoclast activity. Modified You-Gui-Yin (MYGY), a traditional Chinese herbal formula, is able to effectively treat PMOP, while the critical components and pharmacological mechanisms of MYGY are still unclear. In this study, we aimed to investigate the therapeutic effects and underlying mechanisms of N-butanol extract of MYGY (MYGY-Nb) in ovariectomized (OVX)-induced osteoporosis mice. Histological staining and micro-computed tomography (μCT) analysis showed that MYGY-Nb was more effective in the suppression of OVX-induced bone loss than MYGY original formula. Subsequently, liquid chromatography and mass spectrometry analysis identified 16 critical compounds of MYGY-Nb and some of them are reported to affect osteoclast functions. Furthermore, in vivo and in vitro experiments demonstrated that MYGY-Nb significantly attenuated osteoclastogenesis by down-regulating RANKL-mediated NF-κB signaling. In conclusion, our study indicated that MYGY-Nb suppresses NF-κB signaling and osteoclast formation to mitigate bone loss in PMOP, implying that MYGY-Nb and its compounds are potential candidates for development of anti-PMOP drugs.

Hinokitiol inhibits RANKL-induced osteoclastogenesis in vitro and prevents ovariectomy-induced bone loss in vivo

Osteoporosis is a metabolic bone-loss disease characterized by abnormally excessive osteoclast formation and bone resorption. Identification of natural medicines that can inhibit osteoclastogenesis, bone resorption, and receptor activator of nuclear factor-κB ligand (RANKL)-induced signaling is necessary for improved treatment of osteoporosis. In this study, hinokitiol, a tropolone-related compound extracted from the heart wood of several cupressaceous plants, was found to inhibit RANKL-induced osteoclast formation and bone resorption in vitro. Hinokitiol inhibited early activation of the ERK, p38, and JNK-MAPK pathways, thereby suppressing the activity and expression of downstream factors (c-Jun, c-Fos, and NFATC1). Consistent with the above in vitro findings, hinokitiol treatment protected against ovariectomy-induced bone loss in vivo. Collectively, our results imply that hinokitiol can potentially serve as an effective agent for treating osteoclast-induced osteoporosis.

Artesunate inhibits osteoclastogenesis through the miR-503/RANK axis

Osteoporosis is a metabolic bone disease that is characterized by decreased bone density and strength due to excessive loss of bone protein and mineral content, which can be induced by increased osteoclast activity. Developing agents targeting osteoclast activation is considered to be the most effective method to reverse bone destruction and alleviate the pain caused by osteoporosis. MTT assay was conducted to detect the cell viability after artesunate treatment of RAW264.7 cells. TRACP staining and pit formation assays were performed to examine the TRACP-positive cells and pit-forming activity of osteoclasts. qRT-PCR and Western blot analysis were performed to assess the mRNA and protein expression levels of the osteoclastogenesis-related genes NFATc1, TRAP, and cathepsin k. The protein levels of RANK, p-Akt, p-p38, and p-ERK were examined by Western blotting. Luciferase reporter assay was conducted to determine whether miR-503 targeted RANK directly. Artesunate inhibited TRACP-positive cells and the pit-forming activity of osteoclasts. However, artesunate increased the expression of miR-503. Artesunate suppressed osteoclastogenesis-related gene expression and RANKL-induced activation of MAPKs and the AKT pathway. In addition, miR-503 inhibited RANK expression by directly targeting RANK during osteoclast differentiation. Artesunate inhibited osteoclastogenesis and osteoclast functions in vitro by regulating the miR-503/RANK axis and suppressing the MAPK and AKT pathways, which resulted in decreased expression of osteoclastogenesis-related markers.

Kirenol inhibits RANKL-induced osteoclastogenesis and prevents ovariectomized-induced osteoporosis via suppressing the Ca2+-NFATc1 and Cav-1 signaling pathways

BACKGROUND

Osteoporosis is a threat to aged people who have excessive osteoclast activation and bone resorption, subsequently causing fracture and even disability. Inhibiting osteoclast differentiation and absorptive functions has become an efficient approach to treat osteoporosis, but osteoclast-targeting inhibitors available clinically remain rare. Kirenol (Kir), a bioactive diterpenoid derived from an antirheumatic Chinese herbal medicine Herba Siegesbeckiae, can treat collagen-induced arthritis in vivo and promote osteoblast differentiation in vitro, while the effects of Kir on osteoclasts are still unclear.

PURPOSE

We explore the role of Kir on RANKL-induced osteoclastogenesis in vitro and bone loss in vivo.

METHODS

The in vitro effects of Kir on osteoclast differentiation, bone resorption and the underlying mechanisms were evaluated with bone marrow-derived macrophages (BMMs). In vivo experiments were performed using an ovariectomy (OVX)-induced osteoporosis model.

RESULTS

We found that Kir remarkably inhibited osteoclast generation and bone resorption in vitro. Mechanistically, Kir significantly inhibited F-actinring formation and repressed RANKL-induced NF-κB p65 activation and p-p38, p-ERK and c-Fos expression. Moreover, Kir inhibited both the expression and nuclear translocation of NFATc1. Ca2+ oscillation and caveolin-1 (Cav-1) were also reduced by Kir during osteoclastogenesis in vitro. Consistent with these findings, 2-10 mg/kg Kir attenuated OVX-induced osteoporosis in vivo as evidenced by decreased osteoclast numbers and downregulated Cav-1 and NFATc1 expression.

CONCLUSIONS

Kir suppresses osteoclastogenesis and the Cav-1/NFATc1 signaling pathway both in vitro and in vivo and protects against OVX-induced osteoporosis. Our findings reveal Kir as a potential safe oral treatment for osteoporosis.

A marine fungus-derived nitrobenzoyl sesquiterpenoid suppresses receptor activator of NF-κB ligand-induced osteoclastogenesis and inflammatory bone destruction

BACKGROUND AND PURPOSE

Osteoclasts are unique cells to absorb bone. Targeting osteoclast differentiation is a therapeutic strategy for osteolytic diseases. Natural marine products have already become important sources of new drugs. The naturally occurring nitrobenzoyl sesquiterpenoids first identified from marine fungi in 1998 are bioactive compounds with a special structure, but their pharmacological functions are largely unknown. Here, we investigated six marine fungus-derived nitrobenzoyl sesquiterpenoids on osteoclastogenesis and elucidated the mechanisms.

EXPERIMENTAL APPROACH

Compounds were first tested by RANKL-induced NF-κB luciferase activity and osteoclastic TRAP assay, followed by molecular docking to characterize the structure-activity relationship. The effects and mechanisms of the most potent nitrobenzoyl sesquiterpenoid on RANKL-induced osteoclastogenesis and bone resorption were further evaluated in vitro. Micro-CT and histology analysis were used to assess the prevention of bone destruction by nitrobenzoyl sesquiterpenoids in vivo.

KEY RESULTS

Nitrobenzoyl sesquiterpenoid 4, with a nitrobenzoyl moiety at C-14 and a hydroxyl group at C-9, was the most active compound on NF-κB activity and osteoclastogenesis. Consequently, nitrobenzoyl sesquiterpenoid 4 exhibited suppression of RANKL-induced osteoclastogenesis and bone resorption from 0.5 μM. It blocked RANKL-induced IκBa phosphorylation, NF-κB p65 and RelB nuclear translocation, NFATc1 activation, reduced DC-STAMP but not c-Fos expression during osteoclastogenesis in vitro. Nitrobenzoyl sesquiterpenoid 4 also ameliorated LPS-induced osteolysis in vivo.

CONCLUSION AND IMPLICATIONS

These results highlighted nitrobenzoyl sesquiterpenoid 4 as a novel inhibitor of osteoclast differentiation. This marine-derived sesquiterpenoid is a promising lead compound for the treatment of osteolytic diseases.

Triptolide prevents bone loss via suppressing osteoclastogenesis through inhibiting PI3K-AKT-NFATc1 pathway

Bone loss (osteopenia) is a common complication in human solid tumour. In addition, after surgical treatment of gynaecological tumour, osteoporosis often occurs due to the withdrawal of oestrogen. The major characteristic of osteoporosis is the low bone mass with micro-architectural deteriorated bone tissue. And the main cause is the overactivation of osteoclastogenesis, which is one of the most important therapeutic targets. Inflammation could induce the interaction of RANKL/RANK, which is the promoter of osteoclastogenesis. Triptolide is derived from the traditional Chinese herb lei gong teng, presented multiple biological effects, including anti-cancer, anti-inflammation and immunosuppression. We hypothesized that triptolide could inhibits osteoclastogenesis by suppressing inflammation activation. In this study, we confirmed that triptolide could suppress RANKL-induced osteoclastogenesis in bone marrow mononuclear cells (BMMCs) and RAW264.7 cells and inhibited the osteoclast bone resorption functions. PI3K-AKT-NFATc1 pathway is one of the most important downstream pathways of RANKL-induced osteogenesis. The experiments in vitro indicated that triptolide suppresses the activation of PI3K-AKT-NFATc1 pathway and the target point located at the upstream of AKT because both NFATc1 overexpression and AKT phosphorylation could ameliorate the triptolide suppression effects. The expression of MDM2 was elevated, which demonstrated the MDM-p53-induced cell death might contribute to the osteoclastogenesis suppression. Ovariectomy-induced bone loss and inflammation activation were also found to be ameliorated in the experiments in vivo. In summary, the new effect of anti-cancer drug triptolide was demonstrated to be anti-osteoclastogenesis, and we demonstrated triptolide might be a promising therapy for bone loss caused by tumour.

Anacardic acid inhibits RANKL-induced osteoclastogenesis in vitro and prevents ovariectomy-induced bone loss in vivo

Postmenopausal osteoporosis is the most common form of primary osteoporosis, and the incidence of the condition is rapidly increasing. In consideration of the limitations of current therapeutic options for the treatment of postmenopausal osteoporosis, there is an urgent need to develop safer alternatives. Anacardic acid, a natural phenolic acid compound extracted from cashew nut shell, possesses potent antitumor and anti-inflammatory effects and inhibits NF-κB signaling. However, its effect on osteoclasts remains unknown. This study reports the first evidence for the antiosteoclastogenic and antiresorptive effects of anacardic acid on bone marrow-derived macrophage-derived osteoclasts. Mechanistically, anacardic acid disrupts the phosphorylation of TGF-β activated kinase 1 and subsequently suppresses multiple receptor activator of NF-κB ligand-induced signaling cascades, ultimately inhibiting the induction and activation of the crucial osteoclast transcriptional factor nuclear factor of activated T-cell cytoplasmic 1. Consistent with cellular results in vitro, anacardic acid treatment improves bone density in the murine model of ovariectomy-induced bone loss. Taken together, our study provides promising evidence for the therapeutic application of anacardic acid as a new potential pharmacological treatment for osteoporosis.-Zhao, K., Jia, Y., Peng, J., Pang, C., Zhang, T., Han, W., Jiang, J., Lu, X., Zhu, J., Qian, Y. Anacardic acid inhibits RANKL-induced osteoclastogenesis in vitro and prevents ovariectomy-induced bone loss in vivo.

A Matrine Derivative M54 Suppresses Osteoclastogenesis and Prevents Ovariectomy-Induced Bone Loss by Targeting Ribosomal Protein S5

Post-menopausal osteoporosis (PMOP) is a metabolic bone disorder characterized by low bone mass and micro-architectural deterioration of bone tissue. The over-activated osteoclastogenesis, which plays an important role in osteoporosis, has become an important therapeutic target. M54 was a bioactive derivative of the Chinese traditional herb matrine. We found that M54 could suppress RANKL-induced osteoclastogenesis in bone marrow mononuclear cells and RAW264.7 cells through suppressing NF-κB, PI3K/AKT, and MAPKs pathways activity in vitro, and prevent ovariectomy-induced bone loss in vivo. Our previous study has proved that ribosomal protein S5 (RPS5) was a direct target of M19, based on which M54 was synthesized. Thus we deduced that M54 also targeted RPS5. During osteoclastogenesis, the RPS5 level in RAW264.7 cells was significantly down-regulated while M54 could maintain its level. After RPS5 was silenced, the inhibitory effects of M54 on osteoclastogenesis were partially compromised, indicating that M54 took effects through targeting RPS5. In summary, M54 was a potential clinical medicine for post-menopause osteoporosis treatment, and RPS5 is a possible key protein in PMOP.

Gastrodin reduces IL-1β-induced apoptosis, inflammation, and matrix catabolism in osteoarthritis chondrocytes and attenuates rat cartilage degeneration in vivo

Therapeutics for osteoarthritis (OA) are intended to restore chondrocyte function and inhibit cell apoptosis. Previous studies have shown that gastrodin had anti-apoptotic and anti- inflammatory effects. However, little is known about whether gastrodin has protective effects against the processes of OA. We studied the potential effects of gastrodin on chondrocytes and the underlying mechanisms. Our results showed that gastrodin could prevent chondrocyte apoptosis induced by IL-1β. Additionally, gastrodin suppressed the nuclear factor kappa B (NF-κB) pathway, decreased the release of inflammatory mediators (IL-6, TNF-α), and reduced matrix catabolism in IL-1β-treated chondrocytes. Furthermore, gastrodin ameliorated rat cartilage degeneration in an OA model of knee joints in vivo, suggesting its potential as a candidate therapeutic for OA.

Matrine derivate MASM uncovers a novel function for ribosomal protein S5 in osteoclastogenesis and postmenopausal osteoporosis

Postmenopausal osteoporosis (POMP) is a public health problem characterized by decreased bone density and increased fracture risk. Over-activated osteoclastogenesis plays a vital role in POMP. Here we developed a novel bioactive compound MASM (M19) based on sophocarpine. Although it showed no significant effects on osteogenesis and adipogenesis for bone marrow-derived mesenchymal stem cells (BMSCs) in vitro, it could significantly inhibit RANKL/M-CSF induced osteoclastogenesis through suppressing NF-κB, MAPKs and PI3K/Akt pathways in vitro and ameliorate bone loss in ovariectomized mice in vivo. Ribosomal protein s5 (RPS5) has been identified as a target of M19 and regulates PI3K/Akt, NF-κB and MAPKs pathways in osteoclastogenesis. Overexpressions of RPS5 synergistically inhibited osteoclastogenesis with M19 while silencing RPS5 compromised M19 inhibitory effects on osteoclastogenesis in vitro. Among the three pathways, Akt plays a major role in M19 effects. The Akt activator SC₇₉ partially reversed the inhibitory effects on osteoclastogenesis by M19 and RPS5-knocking-down. It indicates that RPS5 serves as a potential candidate target for inhibiting osteoclastogenesis and osteoporosis therapy and M19 is a promising agent for POMP treatment.

Matrine prevents bone loss in ovariectomized mice by inhibiting RANKL-induced osteoclastogenesis

Osteoporosis is a metabolic bone disease characterized by decreased bone density and strength due to excessive loss of bone protein and mineral content. The imbalance between osteogenesis by osteoblasts and osteoclastogenesis by osteoclasts contributes to the pathogenesis of postmenopausal osteoporosis. Estrogen withdrawal leads to increased levels of proinflammatory cytokines. Overactivated osteoclasts by inflammation play a vital role in the imbalance. Matrine is an alkaloid found in plants from the Sophora genus with various pharmacological effects, including anti-inflammatory activity. Here we demonstrate that matrine significantly prevented ovariectomy-induced bone loss and inhibited osteoclastogenesis in vivo with decreased serum levels of TRAcp5b, TNF-α, and IL-6. In vitro matrine significantly inhibited osteoclast differentiation induced by receptor activator for NF-κB ligand (RANKL) and M-CSF in bone marrow monocytes and RAW264.7 cells as demonstrated by tartrate-resistant acid phosphatase (TRAP) staining and actin-ring formation as well as bone resorption through pit formation assays. For molecular mechanisms, matrine abrogated RANKL-induced activation of NF-κB, AKT, and MAPK pathways and suppressed osteoclastogenesis-related marker expression, including matrix metalloproteinase 9, NFATc1, TRAP, C-Src, and cathepsin K. Our study demonstrates that matrine inhibits osteoclastogenesis through modulation of multiple pathways and that matrine is a promising agent in the treatment of osteoclast-related diseases such as osteoporosis.-Chen, X., Zhi, X., Pan, P., Cui, J., Cao, L., Weng, W., Zhou, Q., Wang, L., Zhai, X. Zhao, Q., Hu, H., Huang, B., Su, J. Matrine prevents bone loss in ovariectomized mice by inhibiting RANKL-induced osteoclastogenesis.