Effects of denosumab on bone mineral density and bone turnover in postmenopausal women

What is the Risk of Developing Osteonecrosis Following Dental Extractions for Patients on Denosumab for Osteoporosis?

PURPOSE

Osteonecrosis of the jaws (ONJ) occurs in patients on antiresorptive drugs for osteoporosis with the risk with oral bisphosphonates being known to be of the order of 0.1 to 0.3% while the risk for patients on denosumab for osteoporosis is not known. The aim of this study was to determine the risk of developing ONJ in a consecutive series of patients on denosumab for osteoporosis having dental extractions.

MATERIAL AND METHODS

A prospective cohort study of patients on denosumab for osteoporosis having dental extractions in the period January 1, 2017 and June 30, 2021 were compared to a control group not on antiresorptives. Detailed demographic records including length of time on antiresorptives and CTX values were obtained. Comparison to further define risk factors was made between those patients developing ONJ to those who didn't.

RESULTS

The treatment group included 427 patients who were on denosumab for osteoporosis; they collectively underwent 561 episodes of dental treatment involving extractions for a total of 1081 extractions, with 10 developing ONJ (risk 2.3%). The control group consisted of 299 patients who were not taking denosumab; they collectively underwent 315 episodes of dental treatment for a total of 669 extractions, and none of them developed ONJ. There were significant differences in age and sex, but not medical comorbidities between the treatment and control groups. Within the treatment group, there were no significant differences in any of these characteristics between those who did, and those who didn't, develop ONJ. Within the treatment group, the number of extractions modified the risk of developing ONJ (odds ratio, 1.35; confidence interval, 1.1-1.7). Of the 76 patients who had extractions between 6 and 7 months after the last denosumab injection, none developed ONJ.

CONCLUSIONS

The risk of ONJ in patients on denosumab for osteoporosis is a magnitude greater than for patients on the oral bisphosphonates 2.3% v 0 - 0.3%, which is 7.7 times more likely. Number of extractions and early resumption of the next dose of denosumab increases the risk of ONJ.

Nanotechnology for Targeted Drug Delivery to Treat Osteoporosis

Bone diseases such as rheumatoid arthritis, Paget's disease, and osteoporosis cause mortality and mobility limits. Nanomedicine and nano delivery systems have been utilised to deliver active drug moiety to the precisely targeted site in a controlled manner, and it serves as a means of diagnostic tools. The utilisation of nanomedicine is expanding vigorously for assured targeting and efficient drug delivery. Nanotechnology offers various advantages, such as site-specific targeting, precise drug release kinetics, and improved bone mineral density. Recent medications available for osteoporosis are not viable due to the adverse effects associated with them and low patient compliance. There is an urgent need to develop biocompatible and appropriate drug delivery nanocarriers such as nanoparticles, liposomes, hydrogels, dendrimers, micelles, mesoporous particles, etc. These carriers enhance drug delivery and therapeutic effectiveness in bone tissues. The use of nanotechnology is also associated with toxicity. This article presents the review of various reports on nanocarrier systems and biologics for the treatment of osteoporosis. It aims to provide researchers with a clue for inventing a new drug delivery system with site-specific targeting for the treatment of osteoporosis.

Inhibition of Neddylation Suppresses Osteoclast Differentiation and Function In Vitro and Alleviates Osteoporosis In Vivo

Neddylation, or the covalent addition of NEDD8 to specific lysine residue of proteins, is a reversible posttranslational modification, which regulates numerous biological functions; however, its involvement and therapeutic significance in osteoporosis remains unknown. Our results revealed that during the soluble receptor activator of nuclear factor-κB ligand (sRANKL)-stimulated osteoclast differentiation, the neddylation and expression of UBA3, the NEDD8-activating enzyme (NAE) catalytic subunit, were dose- and time-dependently upregulated in RAW 264.7 macrophages. UBA3 knockdown for diminishing NAE activity or administering low doses of the NAE inhibitor MLN4924 significantly suppressed sRANKL-stimulated osteoclast differentiation and bone-resorbing activity in the macrophages by inhibiting sRANKL-stimulated neddylation and tumor necrosis factor receptor-associated factor 6 (TRAF6)-activated transforming growth factor-β-activated kinase 1 (TAK1) downstream signaling for diminishing nuclear factor-activated T cells c1 (NFATc1) expression. sRANKL enhanced the interaction of TRAF6 with the neddylated proteins and the polyubiquitination of TRAF6's lysine 63, which activated TAK1 downstream signaling; however, this process was inhibited by MLN4924. MLN4924 significantly reduced osteoporosis in an ovariectomy- and sRANKL-induced osteoporosis mouse model in vivo. Our novel finding was that NAE-mediated neddylation participates in RANKL-activated TRAF6-TAK1-NFATc1 signaling during osteoclast differentiation and osteoporosis, suggesting that neddylation may be a new target for treating osteoporosis.

Melatonin Inhibits Osteoclastogenesis and Bone Loss in Ovariectomized Mice by Regulating PRMT1-Mediated Signaling

Melatonin, a pineal gland hormone, has been suggested to treat postmenopausal osteoporosis due to its inhibitory effect on osteoclast differentiation. We previously reported that protein arginine methyltransferase 1 (PRMT1) was an important mediator of receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis. However, the relationship between melatonin and PRMT1 in osteoclast differentiation and estrogen deficiency-induced osteoporosis is unclear. In this study, we investigated the inhibitory mechanisms of melatonin in vitro and in vivo by focusing on PRMT1. Melatonin treatment effectively blocked RANKL-induced osteoclastogenesis by inhibiting PRMT1 and asymmetric dimethylarginine (ADMA) expression. RANKL-induced tumor necrosis factor receptor-associated factor 6 (TRAF6) and the phosphorylation of JNK were also suppressed by melatonin, and TRAF6 siRNA attenuated RANKL-induced p-JNK and PRMT1 production. Melatonin inhibited the transcriptional activity of NF-κB by interfering with the binding of PRMT1 and NF-κB subunit p65 in RANKL-treated bone marrow-derived macrophages. Our results also revealed that melatonin inhibits RANKL-induced PRMT1 expression through receptors-independent pathway. Thus, the anti-osteoclastogenic effect of melatonin was mediated by a cascade of inhibition of RANKL-induced TRAF6, JNK, PRMT1, and NF-κB signaling in melatonin receptors-independent pathway. In vivo, ovariectomy caused significant decreases in bone mineral density, but melatonin treatment alleviated the ovariectomized (OVX)-induced bone loss by inhibiting bone resorption. Furthermore, the expression PRMT1 and TRAP mRNA was upregulated in OVX-femurs, but effectively suppressed by melatonin injection. These findings suggest that melatonin inhibited osteoclast differentiation and estrogen deficiency-induced osteoporosis by suppressing RANKL-induced TRAF6, JNK, PRMT1, and NF-κB signaling cascades in melatonin receptors-independent pathway.

Denosumab-Induced Immune Hepatitis

Denosumab–Prolia®, Xgeva® (Amgen) is a fully human antibody to the receptor activator of the nuclear factor-K ligand (RANKL). Hepatotoxicity is extremely rare, with only one reported case of immune origin. We present a second case of hepatotoxicity resulting from an immune reaction to denosumab. A 43-year-old female was referred to the Endocrinology, Diabetes & Metabolism Department for treatment of low bone mineral density (BMD) following endocrine therapy with letrozole and lucrin because of breast cancer. She developed premature menopause at the age of 36 years when she underwent a left lumpectomy due to an infiltrating duct carcinoma of the breast (T1 NO MO) and was subsequently started on endocrine therapy. Denosumab was started to prevent osteoporosis. On the third year after starting on denosumab and one month after she received the last injection, she became ill. The routine biochemical analysis showed that the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) rose appreciatively to 10 times the upper limit of normal (ULN). The gamma-glutamyl transferase (GGT) level was elevated slightly to 67 U/L (0–38 U/L). The serum gamma-globulin level was elevated to 1.72 g/dL (0.7–1.6 gr/dl), while the total bilirubin (TB) and serum albumin levels were normal. A liver biopsy revealed a moderate to severe chronic inflammatory infiltrate containing MUM-1 positive plasma cells. In addition, numerous CD-3 positive small T lymphocytes and few CD-20 positive B lymphocytes and eosinophils were seen in the portal tracts. Moderate to severe interface hepatitis, bile duct proliferation and mild portal fibrosis were also identified. The results could be consistent with the diagnosis of drug-induced liver injury (DILI).

Eudebeiolide B Inhibits Osteoclastogenesis and Prevents Ovariectomy-Induced Bone Loss by Regulating RANKL-Induced NF-κB, c-Fos and Calcium Signaling

Eudebeiolide B is a eudesmane-type sesquiterpenoid compound isolated from Salvia plebeia R. Br., and little is known about its biological activity. In this study, we investigated the effects of eudebeiolide B on osteoblast differentiation, receptor activator nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis in vitro and ovariectomy-induced bone loss in vivo. Eudebeiolide B induced the expression of alkaline phosphatase (ALP) and calcium accumulation during MC3T3-E1 osteoblast differentiation. In mouse bone marrow macrophages (BMMs), eudebeiolide B suppressed RANKL-induced osteoclast differentiation of BMMs and bone resorption. Eudebeiolide B downregulated the expression of nuclear factor of activated T-cells 1 (NFATc1) and c-fos, transcription factors induced by RANKL. Moreover, eudebeiolide B attenuated the RANKL-induced expression of osteoclastogenesis-related genes, including cathepsin K (Ctsk), matrix metalloproteinase 9 (MMP9) and dendrocyte expressed seven transmembrane protein (DC-STAMP). Regarding the molecular mechanism, eudebeiolide B inhibited the phosphorylation of Akt and NF-κB p65. In addition, it downregulated the expression of cAMP response element-binding protein (CREB), Bruton's tyrosine kinase (Btk) and phospholipase Cγ2 (PLCγ2) in RANKL-induced calcium signaling. In an ovariectomized (OVX) mouse model, intragastric injection of eudebeiolide B prevented OVX-induced bone loss, as shown by bone mineral density and contents, microarchitecture parameters and serum levels of bone turnover markers. Eudebeiolide B not only promoted osteoblast differentiation but inhibited RANKL-induced osteoclastogenesis through calcium signaling and prevented OVX-induced bone loss. Therefore, eudebeiolide B may be a new therapeutic agent for osteoclast-related diseases, including osteoporosis, rheumatoid arthritis and periodontitis.

Recommendations for the management of patients with systemic rheumatic diseases during the coronavirus disease pandemic

Patients with systemic rheumatic diseases (SRD) are vulnerable for coronavirus disease (COVID-19). The Korean College of Rheumatology recognized the urgent need to develop recommendations for rheumatologists and other physicians to manage patients with SRD during the COVID-19 pandemic. The working group was organized and was responsible for selecting key health questions, searching and reviewing the available literature, and formulating statements. The appropriateness of the statements was evaluated by voting panels using the modified Delphi method. Four general principles and thirteen individual recommendations were finalized through expert consensus based on the available evidence. The recommendations included preventive measures against COVID-19, medicinal treatment for stable or active SRD patients without COVID-19, medicinal treatment for SRD patients with COVID-19, and patient evaluation and monitoring. Medicinal treatments were categorized according to the status with respect to both COVID-19 and SRD. These recommendations should serve as a reference for individualized treatment for patients with SRD. As new evidence is emerging, an immediate update will be required.

A Review on the Role of Denosumab in Fracture Prevention

Denosumab is a receptor activator of nuclear factor kappa-Β ligand inhibitor, which suppresses the bone resorption process to preserve bone mass. It is usually recommended to postmenopausal women and men with high fracture risk. With the recent publication of the results from FREEDOM study and its extension, the long-term effect of denosumab in preventing fragility fractures has been put forward. This review aims at summarising the evidence of denosumab in reducing fracture risk and its safety derived from clinical studies. Most of the evidence are derived from FREEDOM trials up to 10 years of exposure. Denosumab is reported to prevent vertebral and non-vertebral fractures. It is also proven effective in Japanese women, patients with chronic kidney diseases and breast cancer patients receiving antineoplastic therapy. Denosumab discontinuation leads to high remodeling, loss of bone mineral density and increased fracture risk. These negative effects might be preventable by bisphosphonate treatment. The safety profile of denosumab is consistent with increased years of exposure. In conclusion, denosumab is a safe and effective option for reducing fracture risk among patients with osteoporosis.

The preventive effect of Cuscutae Semen polysaccharide on bone loss in the ovariectomized rat model

The seed of Cuscutae Semen has been used as a functional food to prevent osteoporosis and aging, and improve sexual function in Traditional Chinese Medicine. However, there is a little report on its beneficial effects on osteoporosis. The purpose of our study was to explore whether Cuscutae Semen polysaccharide (CSP) could prevent osteoporosis induced by estrogen deficiency in the ovariectomized rat model. The preventive effect of CSP was assessed using the ovariectomized (OVX) rat model by treatment with vehicle or CSP for 12 weeks. Serum indexes related to osteogenesis were measured using ELISA kits. The underlying mechanism of action of CSP was evaluated by qRT-PCR. The findings showed that CSP exerted bone protective effects via the increase of bone mass, BMD, IGF, TGF-β, osteocalcin, and osteoprotegerin, and the decrease of TRAP and CTX levels in estrogen deficiency-induced osteoporosis, which is mediated by up-regulating the expression levels of Osterix, BMP-2, Runx2, and Smad5 and down-regulating the expression levels of TRAP, NFATc1, c-Fos, and cathepsin K. These findings suggested that CSP exhibited the preventive effects in the estrogen deficiency-induced osteoporosis via promoting bone formation and inhibiting bone resorption. Therefore, CSP may be developed as a promising agent for the prevention of estrogen deficiency-induced osteoporosis.

Water extract of Cnidii Rhizoma suppresses RANKL-induced osteoclastogenesis in RAW 264.7 cell by inhibiting NFATc1/c-Fos signaling and prevents ovariectomized bone loss in SD-rat

Background

Cnidii Rhizoma is the dried root stem of Cnidium officinale Makino. Cnidii Rhizoma (CR) has been used to treat menstrual irregularity, menstrual pain, and menopause in Korea. However, the effects and mechanisms of CR on RANKL-induced osteoclastogenesis pathway remain to be elucidated. In this study, we investigated the effects of CR on the inhibition of bone resorption of osteoclast and its mechanism RANK signaling pathway.

Methods

The anti-osteoclastogenesis of water extract of CR was measured using RAW 264.7 cell. Tartrate-resistant acid phosphatase (TRAP) assay, pit assay, reverse transcription polymerase chain reaction (RT-PCR) and western blot were performed. Moreover, the effects of CR were determined with an in vivo model using ovariectomized (OVX) rats.

Results

CR extract suppressed osteoclastogenesis, its activity and bone resorption activity through decreasing gene of osteoclast-related such as nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1), c-Fos, etc. Moreover, CR extract prevented the bone loss in OVX rats.

Conclusion

These results show that CR has a positive effect on menopausal osteoporosis by suppressing osteoclastogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12906-019-2611-8) contains supplementary material, which is available to authorized users.

Ferutinin directs dental pulp-derived stem cells towards the osteogenic lineage by epigenetically regulating canonical Wnt signaling

Osteoporosis is a silent systemic disease that causes bone deterioration, and affects over 10 million people in the US alone. This study was undertaken to develop a potential stem cell therapy for osteoporosis. We have isolated and expanded human dental pulp-derived stem cells (DPSCs), characterized them, and confirmed their multipotential differentiation abilities. Stem cells often remain quiescent and require activation to differentiate and function. Herein, we show that ferutinin activates DPSCs by modulating the Wnt/β-catenin signaling pathway and key osteoblast-secreted proteins osteocalcin and collagen 1A1 both mRNA and protein levels. To confirm that ferutinin modulates the Wnt pathway, we inhibited glycogen synthase kinase 3 (GSK3) and found that protein expression patterns were similar to those found in ferutinin-treated DPSCs. To evaluate the role of ferutinin in epigenetic regulation of canonical Wnt signaling, the pathway molecules Wnt3a and Dvl3 were analyzed using chromatin immunoprecipitation (ChIP)-quantitative PCR approaches. We confirmed that active marks of both H3K9 acetylation and H3K4 trimethylation were significantly enhanced in the promoter sites of the WNT3A and DVL3 genes in DPSCs after addition of ferutinin. These data provide evidence that ferutinin activates and promotes osteogenic differentiation of DPSCs, and could be used as an inducer as a potentially effective stem cell therapy for osteoporosis.

Eurycoma longifolia, a promising suppressor of RANKL-induced differentiation and activation of osteoclasts: An in vitro mechanistic evaluation

Background

Eurycoma longifolia (E. longifolia) has gained remarkable recognition due to its promising efficacy of stimulating bone formation in androgen-deficient osteoporosis. Numerous in vivo studies have explored the effects of E. longifolia on osteoporosis; however, the in vitro cellular mechanism was not discovered yet.

Objectives

The present study was aimed to investigate the effect of E. longifolia on the proliferation, differentiation and maturation of osteoclasts and the translational mechanism of inhibition of osteoclastogenesis using RAW 264.7 cells as an in vitro osteoclastic model.

Materials and methods

Having assessed cytotoxicity, the cell viability, cell proliferation rate and osteoclastic differentiation capacity of E. longifolia was investigated by evaluating the tartrate-resistant acid phosphatase (TRAP) activity in receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclasts. Taken together, the time-mannered expression of osteoclast-related protein biomarkers such as matrix metallopeptidase-9 (MMP-9), cathepsin-K, TRAP, nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), superoxide (free radicals) generation and superoxide dismutase activity were also measured to comprehend the mechanism of osteoclastogenesis.

Results

E. longifolia did not show significant effects on cytotoxicity and cell proliferation of RAW 264.7 cells; however, a significant inhibition of cells differentiation and maturation of osteoclasts was observed. Moreover, a significant down-regulation of RANKL-induced TRAP activity and expression of MMP-9, cathepsin-K, TRAP, NFATc1 and generation of superoxide and enhanced superoxide dismutase activity was observed in E. longifolia treated cell cultures.

Conclusion

We anticipated that E. longifolia that enhances bone regeneration on the one hand and suppresses osteoclast’s maturation on the other hand may have great therapeutic value in treating osteoporosis and other bone-erosive diseases such as rheumatoid arthritis and metastasis associated with bone loss.

Associations between ERα/β gene polymorphisms and osteoporosis susceptibility and bone mineral density in postmenopausal women: a systematic review and meta-analysis

BACKGROUND

Many studies have reported associations between estrogen receptor (ER) gene polymorphisms and postmenopausal osteoporosis (PMOP) risk and bone mineral density (BMD), but the results are controversial. The aim of the present meta-analysis is to verify the association between ERα and ERβ gene polymorphisms and osteoporosis susceptibility and BMD in postmenopausal women.

METHODS

PubMed, EMBASE, Web of Science, the Cochrane Library and China WeiPu Library were searched. OR and WMD with 95% CI were calculated to assess the association.

RESULTS

Overall, no significant association was observed between ERα XbaI, ERα PvuII and PMOP susceptibility in either overall, Caucasian or Asian populations. ERα G2014A was significantly associated with a decreased risk of PMOP in Caucasian populations. There was a significant association between ERβ RsaI and PMOP risk in both overall and Asian populations. Caucasian PMOP women with ERα XbaI XX and Xx genotypes had a higher LS Z value than women with xx genotype. ERα XbaI XX genotype was associated with increased FN BMD in overall and Caucasian populations, an increased FN Z value in Asians, and a decreased FN Z value in Caucasians. There was also a significant association between ERα XbaI Xx genotype and an increased FN Z value in either Asians or Caucasians. ERα PvuII PP genotype was associated with a low LS Z value in Caucasians and a low FN BMD and Z value in Asians. Pp genotype in PMOP women was significantly correlated with low LS BMD in overall populations, a low FN Z value in either overall, Caucasian or Asian populations.

CONCLUSION

Each ERα and ERβ gene polymorphism might have different impact on PMOP risk and BMD in various ethnicities.

The effects of Lycii Radicis Cortex on RANKL-induced osteoclast differentiation and activation in RAW 264.7 cells

Post-menopausal osteoporosis is a serious age-related disease. After the menopause, estrogen deficiency is common, and excessive osteoclast activity causes osteoporosis. Osteoclasts are multinucleated cells generated from the differentiation of monocyte/macrophage precursor cells such as RAW 264.7 cells. The water extract of Lycii Radicis Cortex (LRC) is made from the dried root bark of Lycium chinense Mill. and is termed 'Jigolpi' in Korea. Its effects on osteoclastogenesis and post‑menopausal osteoporosis had not previously been tested. In the present study, the effect of LRC on receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclast differentiation was demonstrated using a tartrate-resistant acid phosphatase (TRAP) assay and pit formation assay. Moreover, in order to analyze molecular mechanisms, we studied osteoclastogenesis-related markers such as nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), c-Fos, receptor activator of NF-κB (RANK), TRAP, cathepsin K (CTK), matrix metallopeptidase-9 (MMP-9), calcitonin receptor (CTR) and carbonic anhydrase Ⅱ (CAII) using RT-qPCR and western blot analysis. Additionally, we also determined the effect of LRC on an ovariectomized (OVX) rat model. We noted that LRC inhibited RANKL-induced osteoclast differentiation via suppressing osteoclastogenesis-related markers. It also inhibited osteoporosis in the OVX rat model by decreasing loss of bone density and trabecular area. These results suggest that LRC exerts a positive effect on menopausal osteoporosis.

Melatonin, bone regulation and the ubiquitin-proteasome connection: A review

Recently, investigators have shown that ubiquitin-proteasome-mediated protein degradation is critical in regulating the balance between bone formation and bone resorption. The major signal transduction pathways regulating bone formation are the RANK/NF-κB pathway and the Wnt/β-catenin pathway. These signal transduction pathways regulate the activity of mature osteoblasts and osteoclasts. In addition, the Wnt/β-catenin pathway is one of the major signaling pathways in the differentiation of osteoblasts. The ubiquitin ligases that are reported to be of major significance in regulating these pathways are the ubiquitin SCF(B-TrCP) ligase (which regulates activation of NF-κB via degradation of IkBα in osteoclasts, and regulates bone transcription factors via degradation of β-catenin), the Keap-Cul3-Rbx1 ligase (which regulates degradation of IkB kinase, Nrf2, and the antiapoptotic factor Bcl-2), and Smurf1. Also of significance in regulating osteoclastogenesis is the deubiquitinase, CYLD (cylindramatosis protein), which facilitates the separation of NF-κB from IkBα. The degradation of CYLD is also under the regulation of SCF(B-TrCP). Proteasome inhibitors influence the activity of mature osteoblasts and osteoclasts, but also modulate the differentiation of precursor cells into osteoblasts. Preclinical studies show that melatonin also influences bone metabolism by stimulating bone growth and inhibiting osteoclast activity. These actions of melatonin could be interpreted as being mediated by the ubiquitin ligases SCF(B-TrCP) and Keap-Cul3-Rbx, or as an inhibitory effect on proteasomes. Clinical trials of the use of melatonin in the treatment of bone disease, including multiple myeloma, using both continuous and intermittent modes of administration, are warranted.

Odanacatib: An Emerging Novel Treatment Alternative for Postmenopausal Osteoporosis

Odanacatib represents a novel treatment option in the approach of postmenopausal women. Postmenopausal women with osteoporosis experience a disturbance in bone remodeling wherein bone resorption exceeds bone formation. Cathepsin K is a lysosomal cysteine protease found primarily in osteoclasts that plays a major role in the breakdown of bone via its collagenase properties. Targeting a new area of pathophysiology, odanacatib inhibits cathepsin K to reduce bone resorption while preserving bone formation. Phase II and III trials have shown efficacy in increasing bone mineral density in the target treatment group. Overall, safety studies have found odanacatib to be well-tolerated and comparable to placebo; however, some imbalances in adverse events have been observed in the Phase III trials. Current and future studies will analyze the long-term ability of odanacatib in preventing bone fracture.

Effect of the combinatory mixture of Rubus coreanus Miquel and Astragalus membranaceus Bunge extracts on ovariectomy-induced osteoporosis in mice and anti-RANK signaling effect

ETHNOPHARMACOLOGICAL RELEVANCE

Postmenopausal osteoporosis is one of the most common disorders in women after menopause, which is linked to an estrogen deficiency and characterized by an excessive loss of trabecular bone. Rubus coreanus and Astragalus membranaceus have been used for their various pharmacological properties in Asia as a traditional medicine. The present study evaluated the anti-osteoporotic effects of the optimal combination of Rubus coreanus and Astragalus membranaceus in 7:3 mixture (RAM) in ovariectomized (OVX) mice by investigating bone biomechanical properties and the serum levels of TNF-α, osteocalcin, RANKL, OPG, and RANK-RANKL signal-related osteoclast differentiation markers.

MATERIALS AND METHODS

A total of 36 mature female outbred ICR (Institute of cancer research) strain mice (7 weeks) were divided into 6 groups with 7 mice in each group as follows: (1) Sham-operated control mice (Sham) received daily oral phosphate-buffered-saline (PBS) of equal volumes through gavage. (2) OVX mice received a daily oral gavage of PBS (OVX). (3) OVX mice were treated daily with 50mg/kgb.w./day of RAM (4) with 100mg/kgb.w./day of RAM or (5) with 200mg/kgb.w./day of RAM via oral gavage. (6) OVX mice received i.p. injections of 17β-estradiol (E2) (0.1mg/kgb.w./day) three times per week for 12 weeks.

RESULTS

Micro-CT images showed that oral administration of RAM to OVX mice prevented tibial bone loss, preserved trabecular bone microarchitecture, and improved bone biomechanical properties. RAM administration also showed recovery effects on the levels of TNF-α, OPG and RANKL concentration in OVX-states. Additionally, we found that the mechanism by which RAM elicited anti-osteoporotic effects was by down-regulating the expression of TRAF6 and NFATc1 in RANKL-RANK pathway, a route of osteoclast differentiation, followed by reducing the production of osteoclast differentiation factors, calcitonin receptors and cathepsin K.

CONCLUSIONS

Our research strongly suggests that RAM can be clinically used in the prevention and treatment of postmenopausal osteoporosis.

Antiosteoclastic activity of milk thistle extract after ovariectomy to suppress estrogen deficiency-induced osteoporosis

Bone integrity abnormality and imbalance between bone formation by osteoblasts and bone resorption by osteoclasts are known to result in metabolic bone diseases such as osteoporosis. Silymarin-rich milk thistle extract (MTE) and its component silibinin enhanced alkaline phosphatase activity of osteoblasts but reduced tartrate-resistant acid phosphatase (TRAP) activity of osteoclasts. The osteoprotective effects of MTE were comparable to those of estrogenic isoflavone. Low-dose combination of MTE and isoflavone had a pharmacological synergy that may be useful for osteogenic activity. This study attempted to reveal the suppressive effects of MTE on bone loss. C57BL/6 female mice were ovariectomized (OVX) as a model for postmenopausal osteopenia and orally administered 10 mg/kg MTE or silibinin for 8 weeks. The sham-operated mice served as estrogen controls. The treatment of ovariectomized mice with nontoxic MTE and silibinin improved femoral bone mineral density and serum receptor activator of nuclear factor- κB ligand/osteoprotegerin ratio, an index of osteoclastogenic stimulus. In addition, the administration of MTE or silibinin inhibited femoral bone loss induced by ovariectomy and suppressed femoral TRAP activity and cathepsin K induction responsible for osteoclastogenesis and bone resorption. Collectively, oral dosage of MTE containing silibinin in the preclinical setting is effective in preventing estrogen deficiency-induced bone loss.

Vitamin D receptor Fok I polymorphism is associated with low bone mineral density in postmenopausal women: a meta-analysis focused on populations in Asian countries

OBJECTIVE

To explore the associations between vitamin D receptor (VDR) gene polymorphisms (including Fok I, Bsm I and Apa I) and bone mineral density (BMD) in postmenopausal Asian women.

STUDY DESIGN

Databases of Medline, Embase and Wangfang were retrieved to identify eligible studies, with update to 1st February 2012. Standardized mean difference (SMD) and 95% confidence intervals were calculated by using fixed- or random-effect model. Best genetic comparison model was determined by using the Thakkinstian method.

RESULTS

A total of 14 studies with 3243 healthy postmenopausal Asian women were included in this meta-analysis. Overall, pooled analyses indicated that the f allele of VDR Fok I was significantly associated with decreased BMD in the lumbar spine (ff vs. FF: SMD (95% CI): -0.87 (-1.38, -0.35); P=0.001 for lumbar spine; -0.43 (-0.93, 0.06), P=0.086 for femoral neck). In contrast, we did not observe overall associations between VDR Bsm I and Apa I polymorphisms and BMD in either lumbar spine or femoral neck (Bsm I bb vs. BB: SMD (95% CI): 0.61 (-1.30, 2.53), P=0.531 for lumbar spine; Apa I aa vs. AA: SMD (95% CI): 0.66 (-0.16, 1.48), P=0.113 for lumbar spine). When subgroup analyses were conducted according to countries, Indians carrying the VDR Fok I ff genotype were at risk of low BMD at lumbar spine (ff vs. FF: SMD (95% CI): -0.57 (-0.85, -0.29), P<0.001). Sensitivity analyses indicated that no single study had substantial influence on all combined analyses. In addition, no publication bias was identified.

CONCLUSIONS

This meta-analysis indicated that VDR Fok I, rather than Bsm I and Apa I polymorphisms, is associated with bone mineral density in postmenopausal Asian women (especially for Indian women), and can probably be used with other genetic markers together to identify individuals at high risk of osteoporosis.