Brevilin A inhibits RANKL-induced osteoclast differentiation and bone resorption.

Brevilin A (BA) is the primary component of Centipeda minima, which is widely used in Chinese traditional medicine. The anti-inflammatory and anti-tumor properties of BA have been established; however, its function in bone metabolism is not well understood. This study revealed that concentrations of BA below 1.0 µM did not inhibit the proliferation of bone marrow macrophages but did impede the differentiation and bone resorption activity of osteoclasts. Furthermore, BA suppressed the expression of osteoclast-specific genes Mmp9, Acp5, Dc-stamp, Ctsk, and Atp6v0d2. In addition, mTOR, ERK, and NFATc1 activation in bone marrow macrophages were suppressed by BA. As a whole, BA blocks the mTOR and ERK signaling pathways, which is responsible for the development and activity of osteoclasts, and the resorption of bone.

Evaluation of systemic Omega-3 PUFAs effect on orthodontic tooth movement in a rabbit model: RCT.

OBJECTIVES: To evaluate the effect of systemic administration of omega-3 fatty acids on orthodontic tooth movement (OTM) with histological analysis. MATERIALS AND METHODS: OTM was induced in 20 adult albino New Zealand rabbits, divided into omega-3 and control groups, with nickel-titanium coil springs for 21 days. Omega-3 or saline was given every day via oral gavage during the experimental period. Animals were sacrificed for histomorphometric analysis of alveolar bone remodeling after 21 days of OTM. RESULTS: A significant difference in OTM amount was found in the third week of OTM with means of 1.445 ± 0.13 and 1.72 ± 0.15 for the experimental and control groups, respectively. Histomorphometric analysis showed a significant reduction in the area of active bone-resorptive lacunae and a significant increase in osteoblastic activity in the omega-3 group after 3 weeks. CONCLUSIONS: Strong evidence of the osteoclastic inhibitory effect of systemic omega-3 was found, which reduced the percentage and amount of OTM.

[Icariin inhibits thioacetamide-induced osteoclast differentiation through RANKL-p38/ERK-NFAT pathway].

This study aims to investigate the therapeutic effect of icariin(ICA) on thioacetamide(TAA)-induced femoral osteolysis in rats. RAW264.7 cells were treated with TAA and ICA. Cell counting kit-8(CCK-8) assay was used to detect cell proliferation, and tartrate-resistant acid phosphatase(TRAP) staining to examine the formation of osteoclasts. The expression of TRAP, cathepsin K, c-FOS, and NFATc1 in RAW264.7 cells was determined by Western blot and immunofluorescence method. Thirty-two SD rats were randomized into the control group, TAA group(intraperitoneal injection of TAA at 300 mg·kg~(-1)), ICA group(gavage of ICA at 600 mg·kg~(-1)) and TAA + ICA group(intraperitoneal injection of TAA at 300 mg·kg~(-1) and gavage of ICA at 600 mg·kg~(-1)). Administration was performed every other day for 6 weeks. Body weight and length of femur were recorded at execution. Pathological injury and osteoclast differentiation of femur were observed based on hematoxylin-eosin(HE) staining and TRAP staining, and the changes of bone metabolism-related indexes alkaline phosphatase(ALP), calcium(Ca), phosphorus(P), magnesium(Mg), and cross-linked N-telopeptide of type Ⅰ collagen(NTX-Ⅰ) in serum were detected. Three-point bending test and micro-CT were applied to evaluate the quality of femur, and Western blot to detect the levels of osteoclast-related proteins TRAP, cathepsin K, RANK, RANKL, p38, p-p38, ERK, p-ERK, JNK, p-JNK, c-Fos, and NFATc1. The results showed ICA could inhibit TAA-induced production of TRAP-positive cells, the expression of osteoclast-related proteins, and nuclear translocation of NFATc1. ICA alleviated the weight loss, reduction of femur length, and growth inhibition induced by TAA in SD rats. ICA ameliorated the decline of femur elastic modulus caused by TAA and significantly restored trabecular bone mineral density(BMD), trabecular pattern factor(Tb.Pf), trabecular number(Tb.N), trabecular thickness(Tb.Th), and structure model index(SMI), thus improving bone structure. Western blot results showed ICA suppressed femoral osteoclast differentiation induced by TAA through RANKL-p38/ERK-NFATc1 signaling pathway. ICA inhibits osteoclast differentiation and prevents TAA-induced osteolysis by down-regulating RANKL-p38/ERK-NFAT signaling pathway.

Inhibition of SYK and cSrc kinases can protect bone and cartilage in preclinical models of osteoarthritis and rheumatoid arthritis.

The pathophysiology of osteoarthritis (OA) includes the destruction of subchondral bone tissue and inflammation of the synovium. Thus, an effective disease-modifying treatment should act on both of these pathogenetic components. It is known that cSrc kinase is involved in bone and cartilage remodeling, and SYK kinase is associated with the inflammatory component. Thus the aim of this study was to characterize the mechanism of action and efficacy of a small molecule multikinase inhibitor MT-SYK-03 targeting SYK and cSrc kinases among others in different in vitro and in vivo arthritis models. The selectivity of MT-SYK-03 kinase inhibition was assayed on a panel of 341 kinases. The compound was evaluated in a set of in vitro models of OA and in vivo OA and RA models: surgically-induced arthritis (SIA), monosodium iodoacetate-induced arthritis (MIA), collagen-induced arthritis (CIA), adjuvant-induced arthritis (AIA). MT-SYK-03 inhibited cSrc and SYK with IC50 of 14.2 and 23 nM respectively. Only five kinases were inhibited > 90% at 500 nM of MT-SYK-03. In in vitro OA models MT-SYK-03 reduced hypertrophic changes of chondrocytes, bone resorption, and inhibited SYK-mediated inflammatory signaling. MT-SYK-03 showed preferential distribution to joint and bone tissue (in rats) and revealed disease-modifying activity in vivo by halving the depth of cartilage erosion in rat SIA model, and increasing the pain threshold in rat MIA model. Chondroprotective and antiresorptive effects were shown in a monotherapy regime and in combination with methotrexate (MTX) in murine and rat CIA models; an immune-mediated inflammation in rat AIA model was decreased. The obtained preclinical data support inhibition of cSrc and SYK as a viable strategy for disease-modifying treatment of OA. A Phase 2 clinical study of MT-SYK-03 is to be started.

Identification and pharmacokinetics of bioavailable anti-resorptive phytochemicals after oral administration of Psoralea corylifolia L.

Osteoporosis and resulting bone fractures are the major health issues associated with morbidity in the aging population; however, there is no effective treatment that does not cause severe side effects. In East Asia, dried seeds of Psoralea corylifolia L. (PC) have traditionally been used as an herbal medicine to manage urinary tract, cutaneous, and gastrointestinal disorders, as well as bone health. However, the mechanism of action and active biocomponents of PC are unclear. Here, we adopted a pharmacokinetic (PK) study aiming to identify the bioavailable phytochemicals in aqueous and ethanolic extracts of PC (APC) and (EPC), respectively. In addition, we aimed to determine anti-resorptive constituents of PC, which accounted for its beneficial effects on bone health. To this end, we used ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). A rapid, sensitive, and reliable UPLC-MS/MS method was developed and determined the 17 PC ingredients. In the PK study, nine components (two chalcones, two coumarins, one coumestan, two flavonoids, and two isoflavonoids) were observed between 36 and 48 h after oral administration of APC or EPC. Among the bioavailable ingredients, four PC constituents (psoralidin, isobavachin, corylifol A, and neobavaisoflavone) inhibited M-CSF-and RANKL-induced osteoclast differentiation in bone marrow-derived macrophages. In addition, two chalcones and two isoflavonoids markedly inhibited cathepsin K activity, and their binding modes to cathepsin K were determined by molecular docking. In summary, our data suggest that bioavailable multicomponents of PC could contribute to the management of bone health.

The effect of an isoquinoline alkaloid on treatment of periodontitis by regulating the neutrophils chemotaxis.

Neutrophil plays a critical role in the progression of periodontitis. In general, its chemotaxis and activation are benefit for the host defense of bacterial infection and inflammation. However, previous studies have reported that the hyperactive and reactive neutrophils appear to be one of the reasons for tissue destruction in periodontitis tissues. In this study, we investigated an isoquinoline alkaloid Litcubanine A (LA), which from the Traditional Chinese medicinal plant, Litsea cubeba. We found LA showed significant activity in inhibiting neutrophils chemotaxis in the zebrafish yolk sac microinjection model in vivo and in mouse neutrophils in vitro. Further investigation proved that LA could inhibit the expression levels of neutrophil respiratory burst-related and inflammation-related genes CYBB and NCF2, as well as inhibit the activation of MAPK signaling pathway. Moreover, using LA, we successfully achieved the effect of reducing periodontitis bone loss by regulating neutrophil chemotaxis and related functions in a mouse ligature-induced periodontitis model.

Targeting S1PRs as a Therapeutic Strategy for Inflammatory Bone Loss Diseases-Beyond Regulating S1P Signaling.

As G protein coupled receptors, sphingosine-1-phosphate receptors (S1PRs) have recently gained attention for their role in modulating inflammatory bone loss diseases. Notably, in murine studies inhibiting S1PR2 by its specific inhibitor, JTE013, alleviated osteoporosis induced by RANKL and attenuated periodontal alveolar bone loss induced by oral bacterial inflammation. Treatment with a multiple S1PRs modulator, FTY720, also suppressed ovariectomy-induced osteoporosis, collagen or adjuvant-induced arthritis, and apical periodontitis in mice. However, most previous studies and reviews have focused mainly on how S1PRs manipulate S1P signaling pathways, subsequently affecting various diseases. In this review, we summarize the underlying mechanisms associated with JTE013 and FTY720 in modulating inflammatory cytokine release, cell chemotaxis, and osteoclastogenesis, subsequently influencing inflammatory bone loss diseases. Studies from our group and from other labs indicate that S1PRs not only control S1P signaling, they also regulate signaling pathways induced by other stimuli, including bacteria, lipopolysaccharide (LPS), bile acid, receptor activator of nuclear factor κB ligand (RANKL), IL-6, and vitamin D. JTE013 and FTY720 alleviate inflammatory bone loss by decreasing the production of inflammatory cytokines and chemokines, reducing chemotaxis of inflammatory cells from blood circulation to bone and soft tissues, and suppressing RANKL-induced osteoclast formation.

The Dual Role of Vitamin K2 in "Bone-Vascular Crosstalk": Opposite Effects on Bone Loss and Vascular Calcification.

Osteoporosis (OP) and vascular calcification (VC) represent relevant health problems that frequently coexist in the elderly population. Traditionally, they have been considered independent processes, and mainly age-related. However, an increasing number of studies have reported their possible direct correlation, commonly defined as "bone-vascular crosstalk". Vitamin K2 (VitK2), a family of several natural isoforms also known as menaquinones (MK), has recently received particular attention for its role in maintaining calcium homeostasis. In particular, VitK2 deficiency seems to be responsible of the so-called "calcium paradox" phenomenon, characterized by low calcium deposition in the bone and its accumulation in the vessel wall. Since these events may have important clinical consequences, and the role of VitK2 in bone-vascular crosstalk has only partially been explained, this review focuses on its effects on the bone and vascular system by providing a more recent literature update. Overall, the findings reported here propose the VitK2 family as natural bioactive molecules that could be able to play an important role in the prevention of bone loss and vascular calcification, thus encouraging further in-depth studies to achieve its use as a dietary food supplement.

Plumbagin, a Biomolecule with (Anti)Osteoclastic Properties.

Plumbagin is a plant-derived naphthoquinone that is widely used in traditional Asian medicine due to its anti-inflammatory and anti-microbial properties. Additionally, plumbagin is cytotoxic for cancer cells due to its ability to trigger reactive oxygen species (ROS) formation and subsequent apoptosis. Since it was reported that plumbagin may inhibit the differentiation of bone resorbing osteoclasts in cancer-related models, we wanted to elucidate whether plumbagin interferes with cytokine-induced osteoclastogenesis. Using C57BL/6 mice, we unexpectedly found that plumbagin treatment enhanced osteoclast formation and that this effect was most pronounced when cells were pre-treated for 24 h with plumbagin before subsequent M-CSF/RANKL stimulation. Plumbagin caused a fast induction of NFATc1 signalling and mTOR-dependent activation of p70S6 kinase which resulted in the initiation of protein translation. In line with this finding, we observed an increase in RANK surface expression after Plumbagin stimulation that enhanced the responsiveness for subsequent RANKL treatment. However, in Balb/c mice and Balb/c-derived RAW264.7 macrophages, these findings could not be corroborated and osteoclastogenesis was inhibited. Our results suggest that the effects of plumbagin depend on the model system used and can therefore either trigger or inhibit osteoclast formation.

Triterpenoids from Celastrus orbiculatus Thunb. inhibit RANKL-induced osteoclast formation and bone resorption via c-Fos signaling.

Fourteen triterpenes, lup-20(29)-ene-3ß,6ß-diol (1), betulin (2), lupeol caffeate (3), 3ß-caffeoyloxylup-20(29)-en-6α-ol (4), betulin-3ß-yl-caffeate (5), 3ß-trans-feruloylbetulin (6), betulinaldehyde 3-caffeate (7), 3-O-trans-caffeoylbetulinic acid (8), dammarenediol II 3-caffeate (9), 12-oleanene-3ß,6α-diol (10), 11α-hydroxy-3ß-amyrin (11), nivadiol (12), 29-hydroxyfriedelin (13), and celastrusin A (14) were isolated from Celastrus orbiculatus Thunb. and evaluated for their activity on receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast differentiation in bone marrow macrophages (BMMs). Compounds betulin (2), betulin-3ß-yl-caffeate (5), 3ß-trans-feruloylbetulin (6), and 3-O-trans-caffeoylbetulinic acid (8) significantly inhibited osteoclast formation in a dose-dependent manner. Among these, betulin-3ß-yl-caffeate (5) exhibited the most potent inhibitory activity. We demonstrated that betulin-3ß-yl-caffeate (5) suppressed F-actin-ring formation and bone resorption activity. At the molecular level, betulin-3ß-yl-caffeate (5) inhibited RANK-induced expression of c-Fos and the induction of nuclear factor of activated T cells 1 (NFATc1), a key transcription factor for osteoclast formation, and it also downregulated mRNA expression of osteogenesis-associated marker genes including tartrate-resistant acid phosphatase (TRAP), dendritic cell-specific transmembrane protein (DC-STAMP), and matrix metalloprotein (MMP). These results indicate that betulin-3ß-yl-caffeate (5) may be a promising candidate for the treatment of osteoclast-related diseases such as osteoporosis.

Carnosol suppresses RANKL-induced osteoclastogenesis and attenuates titanium particles-induced osteolysis.

Osteolysis is a common medical condition characterized by excessive activity of osteoclasts and bone resorption, leading to severe poor quality of life. It is essential to identify the medications that can effectively suppress the excessive differentiation and function of osteoclasts to prevent and reduce the osteolytic conditions. It has been reported that Carnosol (Car), isolated from rosemary and salvia, has anti-inflammatory, antioxidative, and anticancer effects, but its activity on osteolysis has not been determined. In this study, we found that Car has a strong inhibitory effect on the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation dose-dependently without any observable cytotoxicity. Moreover, Car can inhibit the RANKL-induced osteoclastogenesis and resorptive function via suppressing NFATc1, which is a result of affecting MAPK, NF-κB and Ca2+ signaling pathways. Moreover, the particle-induced osteolysis mouse model confirmed that Car could be effective for the treatment of bone loss in vivo. Taken together, by suppressing the formation and function of RANKL-induced osteoclast, Car, may be a therapeutic supplementary in the prevention or the treatment of osteolysis.

Grape Seed Proanthocyanidin Extract Prevents Bone Loss via Regulation of Osteoclast Differentiation, Apoptosis, and Proliferation.

Dietary procyanidin has been shown to be an important bioactive component that regulates various pharmacological activities to maintain metabolic homeostasis. In particular, grape seed proanthocyanidin extract (GSPE) is a commercially available medicine for the treatment of venous and lymphatic dysfunction. This study aimed to investigate whether GSPE protects against lipopolysaccharide (LPS)-induced bone loss in vivo and the related mechanism of action in vitro. The administration of GSPE restored the inflammatory bone loss phenotype stimulated by acute systemic injection of LPS in vivo. GSPE strongly suppressed receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclast differentiation and bone resorption activity of mature osteoclasts by decreasing the RANKL-induced nuclear factor-κB transcription activity. GSPE mediates this effect through decreased phosphorylation and degradation of NF-κB inhibitor (IκB) by IκB kinaseß, subsequently inhibiting proto-oncogene cellular Fos and nuclear factor of activated T cells. Additionally, GSPE promotes osteoclast proliferation by increasing the phosphorylation of components of the Akt and mitogen-activated protein kinase signaling pathways and it also inhibits apoptosis by decreasing the activity of caspase-8, caspase-9, and caspase-3, as corroborated by a decrease in the Terminal deoxynucleotidyl transferase dUTP nick end labeling -positive cells. Our study suggests a direct effect of GSPE on the proliferation, differentiation, and apoptosis of osteoclasts and reveals the mechanism responsible for the therapeutic potential of GSPE in osteoclast-associated bone metabolism disease.

A GABAergic neural circuit in the ventromedial hypothalamus mediates chronic stress-induced bone loss.

Homeostasis of bone metabolism is regulated by the central nervous system, and mood disorders such as anxiety are associated with bone metabolism abnormalities, yet our understanding of the central neural circuits regulating bone metabolism is limited. Here, we demonstrate that chronic stress in crewmembers resulted in decreased bone density and elevated anxiety in an isolated habitat mimicking a space station. We then used a mouse model to demonstrate that GABAergic neural circuitry in the ventromedial hypothalamus (VMH) mediates chronic stress-induced bone loss. We show that GABAergic inputs in the dorsomedial VMH arise from a specific group of somatostatin neurons in the posterior region of the bed nucleus of the stria terminalis, which is indispensable for stress-induced bone loss and is able to trigger bone loss in the absence of stressors. In addition, the sympathetic system and glutamatergic neurons in the nucleus tractus solitarius were employed to regulate stress-induced bone loss. Our study has therefore identified the central neural mechanism by which chronic stress-induced mood disorders, such as anxiety, influence bone metabolism.

Quercetin prevents bone loss in hindlimb suspension mice via stanniocalcin 1-mediated inhibition of osteoclastogenesis.

Recent studies demonstrate that diet quercetin (Quer) has obvious bone protective effects on ovariectomized rodents but thus far there is no direct evidence to support the inhibitory effect of Quer on bone loss caused by long-term unloading. In the present study, we investigated whether Quer could prevent bone loss induced by unloading in mice. Mice were subjected to hindlimb suspension (HLS) and received Quer (25, 50, 100 mg· kg-1 ·day-1, ig) for 4 weeks. Before euthanasia blood sample was collected; the femurs were harvested and subjected to MicroCT analysis. We showed that Quer administration markedly improved bone microstructure evidenced by dose-dependently reversing the reduction in bone volume per tissue volume, trabecular number, and bone mineral density, and the increase of trabecular spacing in mice with HLS. Analysis of serum markers and bone histometric parameters confirmed that Quer at both middle and high doses significantly decreased bone resorption-related markers collagen type I and tartrate-resistant acid phosphatase 5b, and increased bone formation-related marker procollagen 1 N-terminal propeptide as compared with HLS group. Treatment with Quer (1, 2, 5 µM) dose-dependently inhibited RANKL-induced osteoclastogenesis through promoting the expression of antioxidant hormone stanniocalcin 1 (STC1) and decreasing ROS generation; knockdown of STC1 blocked the inhibitory effect of Quer on ROS generation. Knockdown of STC1 also significantly promoted osteoclastogenesis in primary osteoclasts. In conclusion, Quer protects bones and prevents unloading-caused bone loss in mice through STC1-mediated inhibition of osteoclastogenesis. The findings suggest that Quer has the potential to prevent and treat off-load bone loss as an alternative supplement.

Androgen action on renal calcium and phosphate handling: Effects of bisphosphonate treatment and low calcium diet.

Renal calcium and phosphate handling is an important contributor to mineral homeostasis and bone health and the androgen receptor (AR) is highly expressed in the kidney. We investigated the short term effects of androgen deprivation on renal calcium and phosphate reabsorption, independent of their effects on bone. Two weeks following orchidectomy (ORX) of adult mice, bone loss occurred along with hypercalciuria, which was similarly prevented by testosterone and dihydrotestosterone supplementation. Treatment with bisphosphonates prior to ORX also inhibited hypercalciuria, indicating that the calcium flux originated from the bone. Renal calcium and phosphate transporter expression was increased post-ORX, independent of bisphosphonates. Furthermore, androgen deprivation appeared to stimulate local synthesis of 1,25(OH)2D3. When bisphosphonate-treated mice were fed a low calcium diet, bone resorption was no longer blocked and secondary hyperparathyroidism developed, which was more pronounced in ORX mice than sham-operated mice. In conclusion, this study shows that androgen deprivation increased renal calcium and phosphate transporter expression, independent of bone, and underlines the importance of adequate intestinal calcium supply in circumstances of androgen deprivation and bisphosphonate treatment.

Arecoline suppresses RANKL-induced osteoclast differentiation in vitro and attenuates LPS-induced bone loss in vivo.

BACKGROUND: Areca nut has anti-inflammatory, antiparasitic, antihypertensive, and antidepressant properties. The pathological hallmarks of inflammatory joint diseases are an increased number of osteoclasts and impaired differentiation of osteoblasts, which may disrupt the bone remodeling balance and eventually lead to bone loss. PURPOSE: The present study assessed the effects of arecoline, the main alkaloid found in areca nut, on osteoclast and osteoblast differentiation and function. METHOD: M-CSF/RANKL-stimulated murine bone marrow-derived macrophages (BMMs) were incubated with several concentrations of arecoline, and TRAP staining and pit formation were assessed to monitor osteoclast formation. Quantitative real-time RT-PCR and western blot analyses were used to analyze the expression of osteoclast-associated genes and signaling pathways. The effects of arecoline on bone were investigated in an in vivo mouse model of lipopolysaccharide (LPS)-induced trabecular bone loss after oral administration of arecoline. Alizarin red S staining and assays to measure ALP activity and the transcription level of osteoblast-related genes were used to evaluate the effects of arecoline on osteoblast differentiation and bone mineralization. RESULTS: In a dose-dependent manner, arecoline at concentrations of 50-100 µM reduced both the development of TRAP-positive multinucleated osteoclasts and the formation of resorption pits in M-CSF/RANKL-stimulated BMMs. In M-CSF/RANKL-stimulated BMMs, arecoline also suppressed the expression and translocation of c-Fos and NFATcl, and osteoclast differentiated-related genes via interference with the AKT, MAPK, and NF-kB activation pathways. Femur bone loss and microcomputed tomography parameters were recovered by oral administration of arecoline in the mouse LPS-induced bone loss model. Lastly, arecoline increased ALP activity, bone mineralization, and the expression of osteoblast differentiation-related genes, such as ALP and Runx2, in MC3T3-E1 cells. CONCLUSION: Our data suggest that arecoline may attenuate or prevent bone loss by suppressing osteoclastogenesis and promoting osteoblastogenesis. These findings provide evidence supporting arecoline's use as a potential therapeutic agent in bone-loss disorders and diseases.

Ellagic acid protects ovariectomy-induced bone loss in mice by inhibiting osteoclast differentiation and bone resorption.

Osteoporosis is a devastating disease that features reduced bone quantity and microstructure, which causes fragility fracture and increases mortality, especially in the aged population. Due to the long-term side-effects of current drugs for osteoporosis, it is of importance to find other safe and effective medications. Ellagic acid (EA) is a phenolic compound found in nut galls, plant extracts, and fruits, and exhibits antioxidant and antineoplastic effects. Here, we showed that EA attenuated the formation and function of osteoclast dose-dependently. The underlying mechanism was further discovered by western blot, immunofluorescence assay, and luciferase assay, which elucidated that EA suppressed osteoclastogenesis and bone resorption mainly through attenuating receptor activator of nuclear factor-κB (NF-κB) ligand-induced NF-κB activation and extracellular signal-regulated kinase signaling pathways, accompanied by decreased protein expression of nuclear factor of activated T-cells calcineurin-dependent 1 and c-Fos. Moreover, EA inhibits osteoclast marker genes expression including Dc-stamp, Ctsk, Atp6v0d2, and Acp5. Intriguingly, we also found that EA treatment could significantly protect ovariectomy-induced bone loss in vivo. Conclusively, this study suggested that EA might have the therapeutic potentiality for preventing or treating osteoporosis.

Tubeimoside I suppresses diabetes-induced bone loss in rats, osteoclast formation, and RANKL-induced nuclear factor-κB pathway.

Type 2 diabetes mellitus is often companied with osteoporosis, a process which involves osteoclast activation. In this study, we found tubeimoside I, a natural compound isolated from the Chinese medicinal herb Bolbostemma paniculatum (Maxim) Franquet (Cucurbitaceae), significantly ameliorated the decrease of bone mass in type 2 diabetes-induced osteoporosis in rats. It appears that tubeimoside I exerts this protecting effect through inhibiting osteoclast formation and function. Futhermore, our study showed that tubeimoside I inhibits NF-κB transcriptional activation and degradation of IκBα. Collectively, our results reveal that tubeimoside I attenuates osteoclastogenesis through down-regulating NF-κB signaling pathway, and is a potential candidate for the treatment of bone-destructive diseases like type 2 diabetic osteoporosis.

Hederagenin protects mice against ovariectomy-induced bone loss by inhibiting RANKL-induced osteoclastogenesis and bone resorption.

AIMS: Postmenopausal osteoporosis and other osteolytic bone diseases are often caused by the elevation in osteoclastogenesis and/or increased osteoclastic bone resorption, leading to excessive bone loss. Hederagenin (Hed) is a pentacyclic triterpenoid saponin extracted from various natural medicinal plants and exhibits numerous biological activities and may offer benefits against bone-related conditions. We evaluated the effects of Hed on osteoclast formation and bone resorption in vitro and the in vivo therapeutic benefits in the mouse model of ovariectomy (OVX)-induced bone loss. MAIN METHODS: In vitro, osteoclast formation were determined by TRAcp staining; bone resorption were examined using Hydroxyapatite resorption assay and Podosomal actin belt formation assay; Related molecular mechanisms were determined by western blot assay. Construction of OVX mice by bilateral oophorectomy to simulate bone loss in vivo. KEY FINDINGS: In vitro cellular assays showed that Hed inhibited RANKL-induced osteoclast formation and osteoclast bone (hydroxyapatite) resorption as well as marker gene expression from BMM culture. Mechanistically, Hed attenuated RANKL-induced intracellular reactive oxygen species (ROS) production, and MAPK signaling pathway (ERK and p38) activation which curbed the downstream induction of c-Fos and NFATc1. Consistent with the in vitro findings, Hed administration effectively protected OVX mice from bone loss by reducing osteoclast number and activity on bone surface. SIGNIFICANCE: Our data provided promising evidence for the potential use of Hederagenin in the treatment of osteoclast-mediated osteolytic bone diseases such as postmenopausal osteoporosis.

Dietary Selenium Supplementation Does Not Attenuate Mammary Tumorigenesis-Mediated Bone Loss in Male MMTV-PyMT Mice.

Bone wasting occurs during the progression of breast cancer and contributes to breast cancer mortality. We evaluated the effect of methylseleninic acid (MSeA), an anti-carcinogenic form of selenium, on bone microstructural changes in the presence of mammary tumors in a male breast cancer model of mouse mammary tumor virus-polyomavirus middle T-antigen (MMTV-PyMT). In this study, we performed microcomputed tomographic analysis of femurs and vertebrae collected from a study showing that dietary supplementation with MSeA reduces mammary tumorigenesis in male mice. Compared to age-matched, non-tumor-bearing mice (MMTV-PyMT negative), the presence of mammary tumors significantly reduced the bone volume fraction, trabecular thickness, and bone mineral density while it increased the structure model index in femurs, but not in vertebrae. Moreover, mammary tumorigenesis decreased plasma concentrations of osteocalcin. Supplementation with MSeA did not affect these changes in MMTV-PyMT mice. In conclusion, mammary tumorigenesis caused bone loss in MMTV-PyMT mice. However, dietary supplementation with MSeA did not attenuate mammary tumor-associated bone loss in this model of male breast cancer.