Denosumab, a new pharmacotherapy option for postmenopausal osteoporosis

Emerging Insights into the Endocrine Regulation of Bone Homeostasis by Gut Microbiome

Gut microbiota plays an important role in the regulation of bone homeostasis and bone health. Recent studies showed that these effects could be mediated through microbial metabolites released by the microbiota like short-chain fatty acids, metabolism of endogenous molecules such as bile acids, or a complex interplay between microbiota, the endocrine system, and the immune system. Importantly, some studies showed a reciprocal relationship between the endocrine system and gut microbiota. For instance, postmenopausal estrogen deficiency could lead to dysbiosis of the gut microbiota, which could in turn affect various immune response and bone remodeling. In addition, evidence showed that shift in the indigenous gut microbiota caused by antibiotics treatment may also impact normal skeletal growth and maturation. In this mini-review, we describe recent findings on the role of microbiome in bone homeostasis, with a particular focus on molecular mechanisms and their interactions with the endocrine and immune system. We will also discuss the recent findings on estrogen deficiency and microbiota dysbiosis, and the clinical implications for the development of new therapeutic strategies for osteoporosis and other bone disorders.

Dietary Collagen Hydrolysates Retard Estrogen Deficiency-Induced Bone Loss through Blocking Osteoclastic Activation and Enhancing Osteoblastic Matrix Mineralization

Osteoporosis manifest in postmenopausal women is an osteolytic disease characterized by bone loss, leading to increased susceptibility to bone fractures and frailty. The use of complementary therapies to alleviate postmenopausal osteoporosis is fairly widespread among women. The current study examined that Pangasius hypophthalmus fish skin collagen hydrolysates (fsCH) inhibited ovariectomy (OVX)-induced bone loss by conducting inter-comparative experiments for anti-osteoporotic activity among 206–618 mg/kg fsCH, 2 mg/kg isoflavone, 15 mg/kg glycine–proline–hydroxyproline (GPH) tripeptide, and calcium lactate. Surgical estrogen loss of mice for 8 weeks reduced serum 17β-estradiol levels with uterus atrophy, which was ameliorated by orally administering fsCH or isoflavone to mice. Similar to isoflavone, fsCH containing GPH-enhanced bone mineral density reduced levels of cathepsin K and proton-handling proteins, and elevated collagen 1 level in OVX bones. The treatment with fsCH and isoflavone enhanced the serum levels of collagen synthesis-related procollagen type 1 carboxy/amino-terminal propeptides reduced by OVX, whereas serum levels of osteocalcin and alkaline phosphatase, as well as collagen breakdown-related carboxy/amino-terminal telopeptides of type 1 collagen were reduced in OVX mice treated with fsCH, isoflavone, and calcium lactate. The trabecular bones were newly formed in OVX bones treated with isoflavone and fsCH, but not with calcium lactate. However, a low-dose combination of fsCH and calcium lactate had a beneficial synergy effect on postmenopausal osteoporosis. Furthermore, similar to isoflavone, 15–70 μg/mL fsCH, with its constituents of GPH and dipeptides of glycine–proline and proline–hydroxyproline, enhanced osteogenesis through stimulating differentiation, matrix mineralization, and calcium deposition of MC3T3-E1 osteoblasts. Accordingly, the presence of fsCH may encumber estrogen deficiency-induced bone loss through enhancing osteoclastogenic differentiation and matrix collagen synthesis. Therefore, fsCH may be a natural compound retarding postmenopausal osteoporosis and pathological osteoresorptive disorders.

[Progress of change in bone mineral density after knee arthroplasty]

Objective

To summarize research progress of change in bone mineral density (BMD) after knee arthroplasty and its diagnostic methods, influencing factors, and drug prevention and treatment.

Methods

The relevant literature at home and abroad was reviewed and summarized from research status of the advantages and disadvantages of BMD assessment methods, the trend of changes in BMD after knee arthroplasty and its influencing factors, and the differences in effectiveness of drugs.

Results

The central BMD and mean BMD around the prosthesis decrease after knee arthroplasty, which is closely associated with body position, age, weight, daily activities, and the fixation methods, design, and material of prosthesis. Denosumab, bisphosphonates, and teriparatide et al. can decrease BMD loss after knee arthroplasty.

Conclusion

BMD after knee arthroplasty decreases, which is related to various factors, but the mechanism is unclear. At present, some inhibitors of bone resorption can decrease BMD loss after knee arthroplasty. However, its long-term efficacy remains to be further explored.

Three-year results of denosumab treatment for osteoporosis in women with rheumatoid arthritis and primary osteoporosis: A clinical observational study

INTRODUCTION

This study investigated the results of 3 years of denosumab treatment for osteoporosis in women with rheumatoid arthritis (RA) and primary osteoporosis (PO).

MATERIALS AND METHODS

This study enrolled 112 women with RA (RA group) and 104 women with a PO group who received 60 mg denosumab for 3 years. Bone mineral densitiy (BMD) of the lumbar spine, total hip and femoral neck as well as levels of bone turnover markers [N-terminal propeptide of type I procollagen (P1NP) and tartrate-resistant acid phosphatase-5b (TRACP-5b)] were measured at years 1, 2, and 3.

RESULTS

The percent changes (Δ) in BMD values at years 1, 2, and 3 were as follows: RA group: 6.7 ± 6.2%, 8.9 ± 6.5%, and 9.8 ± 8.2% and PO group: 6.0 ± 4.8%, 8.9 ± 7.5%, and 12.6 ± 8.7% for the lumbar spine; RA group: 4.5 ± 4.6%, 5.2 ± 5.1%, and 6.8 ± 5.9% and PO group: 3.8 ± 4.5%, 4.6 ± 7.4%, and 6.8 ± 4.6% for the total hip; and RA group: 2.7 ± 5.1%, 4.1 ± 6.8%, and 4.3 ± 6.7% and PO group: 3.6 ± 8.0%, 4.5 ± 10.9%, and 5.7 ± 10.5% for the femoral neck, respectively. The ΔBMD for the lumbar spine, total hip, and femoral neck as well as ΔP1NP and ΔTRACP-5b did not differ significantly between the two groups at any time points.

CONCLUSION

Denosumab treatment for osteoporosis had a similar efficacy over 3 years among women with RA and PO. A better understanding of denosumab treatment for this patient population is important in clinical practice.

Denosumab Regulates Gut Microbiota Composition and Cytokines in Dinitrobenzene Sulfonic Acid (DNBS)-Experimental Colitis

The pro-inflammatory mediator receptor activator of nuclear factor-kappa B ligand (RANKL) plays a significant role in the development of rheumatoid arthritis; however, its role in inflammatory bowel disease is unknown. Genome-wide association meta-analysis for Crohn's disease (CD) identified a variant near the TNFSF11 gene that encodes RANKL and CD risk allele increased expression of RANKL in specific cell lines. This study aims to elucidate if the RANKL inhibitor denosumab can reduce the severity of experimental colitis and modify the gut microbiota composition using murine dinitrobenzenesulfonic acid (DNBS)-experimental model of colitis mimicking CD. In colitic conditions, denosumab treatment significantly decreased the pro-inflammatory cytokines IL-6, IL-1β, and TNF-α within the colonic mucosa. Moreover, colitis was accompanied by disruption of gut microbiota, and preventative treatment with denosumab modulated this disruption. Denosumab treatment also modified the alpha- and beta diversity of colonic mucosa and fecal microbiota. These results provide a rationale for considering denosumab as a future potential therapy in CD; however, more detailed experimental and clinical studies are warranted.

Tumor ablation using novel photothermal NaxWO3 nanoparticles against breast cancer osteolytic bone metastasis

Backgrounds

Profiting from the development of nanomaterials, photothermal therapy (PTT) has been discovered as efficient tumor ablation strategy for breast cancer.

Materials and methods

Novel oxygen vacancy-rich tungsten bronze nanoparticles (Na_xWO₃) were synthesized through a simple pyrogenic decomposition process. TEM, XRD, UV-vis-NIR, photothermal conversion ability, and photothermal stability were performed. The viabilities of 293T and 4T1 cells after treating with 200 μg/mL Na_xWO₃ nanoparticles for 24 or 48 hrs were both above 80%, which proved the good biosafety and cytotoxicity of Na_xWO₃ in vitro. Two in vivo breast cancer models, namely percutaneous and intratibial 4T1 models were established and Na_xWO₃ (20 mg/kg) with power intensity of 1.5 W/cm² 980 nm laser photothermal treatment was used in vivo.

Results

We successfully synthesized ~150 nm Na_xWO₃ nanoparticles with desirable PTT effects, as evidenced by the temperature increase from 25.8°C to 41.8°C in 5 mins under the irradiation of 980 nm laser (1 mg/mL). Also, cellular compatibility of Na_xWO₃ nanoparticles was found upon physiologic 293T cells, in contrast with significant cytotoxicity against breast cancer 4T1 cell in vitro dose-dependently. Besides, two in vivo breast cancer models showed the decent tumor ablation ability of Na_xWO₃ nanoparticles, demonstrating percutaneous 4T1 tumor elimination without recurrence during 2 weeks observation as well as intratibial breast cancer inhibition with decreased bone destruction and tumor volume after Na_xWO₃+PTT in vivo.

Conclusion

For the first time, we developed a novel oxygen vacancy-rich tungsten bronze nanoparticles (Na_xWO₃) through a simple pyrogenic decomposition process for PTT. Both in vitro and in vivo experiments showed the good PTT ability and tumor ablation effects of synthesized Na_xWO₃ nanoparticles against breast cancer osteolytic bone metastasis. Additionally, our oxygen-deficient Na_xWO₃ nanoparticles will expand the research horizons of PTT nanomaterials.

The Calcium Culprit: A Case of Denosumab-induced Hypocalcemia

Denosumab is a fully human monoclonal antibody which is used to treat osteoporosis and has been shown to cause hypocalcemia in patients with underlying prostatic and bone malignancies, renal impairment, postmenopausal state, and/or vitamin D deficiency. We present a case of a male patient, with a past medical history negative for the aforementioned conditions, who presented with right shoulder pain and was found to be severely hypocalcemic secondary to denosumab.

Small molecule nAS-E targeting cAMP response element binding protein (CREB) and CREB-binding protein interaction inhibits breast cancer bone metastasis

Bone is the most common metastatic site for breast cancer. The excessive osteoclast activity in the metastatic bone lesions often produces osteolysis. The cyclic-AMP (cAMP)-response element binding protein (CREB) serves a variety of biological functions including the transformation and immortalization of breast cancer cells. In addition, evidence has shown that CREB plays a key role in osteoclastgenesis and bone resorption. Small organic molecules with good pharmacokinetic properties and specificity, targeting CREB-CBP (CREB-binding protein) interaction to inhibit CREB-mediated gene transcription have attracted more considerations as cancer therapeutics. We recently identified naphthol AS-E (nAS-E) as a cell-permeable inhibitor of CREB-mediated gene transcription through inhibiting CREB-CBP interaction. In this study, we tested the effect of nAS-E on breast cancer cell proliferation, survival, migration as well as osteoclast formation and bone resorption in vitro for the first time. Our results demonstrated that nAS-E inhibited breast cancer cell proliferation, migration, survival and suppressed osteoclast differentiation as well as bone resorption through inhibiting CREB-CBP interaction. In addition, the in vivo effect of nAS-E in protecting against breast cancer-induced osteolysis was evaluated. Our results indicated that nAS-E could reverse bone loss induced by MDA-MB-231 tumour. These results suggest that small molecules targeting CREB-CBP interaction to inhibit CREB-mediated gene transcription might be a potential approach for the treatment of breast cancer bone metastasis.

Effects of denosumab treatment on bone mineral density and joint destruction in patients with rheumatoid arthritis

We aimed to investigate the efficacy of denosumab for rheumatoid arthritis (RA). This study enrolled 70 RA patients who received denosumab 60 mg subcutaneous injection at baseline and at 6 months. Bone mineral densities (BMD) of the lumbar spine, total hip, femoral neck, and hand were measured by dual energy X-ray absorptiometry. Changes in total modified Sharp score (mTSS), erosion (EN) score, and joint space narrowing score at baseline from 12 months before and at 12 months from baseline. The mean values of BMD of the lumbar spine, total hip, femoral neck, and hand significantly increased by 7.3, 4.7, 3.9, and 5.4%, respectively, at 12 months. At 12 months from baseline, there were significant decreases in the values of mTSS (1.13 vs. 0.59; p = 0.002) and EN score (0.40 vs. 0.07; p < 0.001), compared with the values at baseline from 12 months before. The existing combined modality therapy with denosumab might be effective for osteoporosis and joint destruction in patients with RA.

MC3T3 infiltration and proliferation in bovine trabecular scaffold regulated by dynamic flow bioreactor and augmented by low-intensity pulsed ultrasound

Background

Low-intensity pulsed ultrasound (LIPUS) has been used in both basic research and clinical settings for its therapeutic potential in promoting tissue healing. Clinical data has shown that LIPUS can accelerate fresh fracture healing. However, the treatment for aging osteoporosis and non-union is still unclear. In addition, the mechanism of ultrasound promoted bone healing has remained unknown.

Objective

It is proposed that noninvasive ultrasound treatment can enhance local fluid flow within the tissue to initiate remodeling and regeneration. The goal of this study was to evaluate the effects of dynamic ultrasound in promoting cellular mechanotransduction within bioengineered organic scaffolds to trigger osteogenesis and mineralization.

Methods

The experiment was designed in two-fold: to evaluate the role of LIPUS on osteoblastic-like (MC3T3) cell proliferation and mineralization in response to acoustic waves, using biomechanical rate-dependent signals in a bioreactor; and, to evaluate the new scaffold experimentation techniques, in order to generate a potential implantable biomaterial for orthopedic tissue regeneration and repair.

Results

LIPUS treatment on MC3T3 cells yielded enhanced cellular mineralization (**p < 0.001) in 3-D scaffolding, but reduced the total cell numbers (*p < 0.05), using Alizarin Red staining and cell counting analyses, respectively, in comparison to the control.

Conclusion

This study suggests that LIPUS, if applied at proper frequency and duty cycle, can promote cell mineralization within the 3-D organic scaffold under in vitro setting. The translational component of this experiment seeks to draw a parallel to the potential pre-treatment of scaffolds for implantation before orthopedic surgery, which could prove to greatly benefit the patient in accelerating fracture healing and tissue regeneration.

The Translational Potential of this Article

LIPUS stimulation was critical in contributing to the mechanical signaling transductions that activated bone enhancement parameters in MC3T3 cells regulated by bioreactor, and thus has potential to change how we pretreat scaffolds for orthopedic surgery and noninvasively accelerate healing in the future, e.g., in an extreme condition such as long-term space mission.

The Effect of Inhalant Organic Dust on Bone Health

PURPOSE OF REVIEW

Agriculture remains a major economic sector globally, and workers experience high rates of chronic inflammatory lung and musculoskeletal diseases. Whereas obstructive pulmonary diseases are known risk factors for bone loss, the underlying relationship between lung inflammation and bone health is not well known.

RECENT FINDINGS

An agriculture organic dust extract inhalation animal model has recently linked lung injury-induced inflammation to systemic bone loss. This process is dependent upon lipopolysaccharide and the toll-like receptor 4 (TLR4) signaling pathway. Downstream systemic interleukin-6 is a key mediator that subsequently activates osteoclastogenesis. Age is a host factor that impacted bone disease with younger mice demonstrating increased susceptibility to bone loss following inhalant exposures as compared to older mice. Supplemental dietary vitamin D was shown to prevent organic dust-induced bone loss, but not lung disease, in animals. Recent animal studies provide new mechanistic insight into the lung-bone inflammatory axis. Host factors, diet, and lipopolysaccharide/TLR4 signaling pathways play a significant role in explaining how inhalant organic dust exposures impact bone health. These investigations might lead to specific targeted therapeutic approaches.

Role of LIGHT in the pathogenesis of joint destruction in rheumatoid arthritis

AIM

To characterise the role of substitutes for receptor-activator nuclear factor kappa-B ligand (RANKL) in rheumatoid arthritis (RA) joint destruction.

METHODS

Synovial fluid (SF) macrophages isolated from the knee joint of RA patients were incubated with 25 ng/mL macrophage-colony stimulating factor (M-CSF) and 50 ng/mL LIGHT (lymphotoxin-like, exhibits inducible expression and competes with herpes simplex virus glycoprotein D for herpes virus entry mediator, a receptor expressed by T lymphocytes) in the presence and absence of 25 ng/mL RANKL and 100 ng/mL osteoprotegerin (OPG) on glass coverslips and dentine slices. Osteoclastogenesis was assessed by the formation of multinucleated cells (MNCs) expressing tartrate-resistant acid phosphatase (TRAP) on coverslips and the extent of lacunar resorption pit formation on dentine slices. The concentration of LIGHT in RA and osteoarthritis (OA) synovial fluid was measured by an enzyme-linked immunosorbent assay (ELISA) and the expression of LIGHT in RA and OA synovium was determined by immunohistochemistry using an indirect immunoperoxidase technique.

RESULTS

In cultures of RA SF macrophages treated with LIGHT and M-CSF, there was significant formation of TRAP + MNCs on coverslips and extensive lacunar resorption pit formation on dentine slices. SF-macrophage-osteoclast differentiation was not inhibited by the addition of OPG, a decoy receptor for RANKL. Resorption pits were smaller and less confluent than in RANKL-treated cultures but the overall percentage area of the dentine slice resorbed was comparable in LIGHT- and RANKL-treated cultures. LIGHT significantly stimulated RANKL-induced lacunar resorption compared with RA SF macrophages treated with either RANKL or LIGHT alone. LIGHT was strongly expressed by synovial lining cells, subintimal macrophages and endothelial cells in RA synovium and the concentration of LIGHT was much higher in RA compared with OA SF.

CONCLUSION

LIGHT is highly expressed in RA synovium and SF, stimulates RANKL-independent/dependent osteoclastogenesis from SF macrophages and may contribute to marginal erosion formation.

F4/80 inhibits osteoclast differentiation via downregulation of nuclear factor of activated T cells, cytoplasmic 1

Osteoclastogenesis is an essential process in bone metabolism, which can be induced by RANKL stimulation. The F4/80 glycoprotein is a member of the EGF-transmembrane 7 (TM7) family and has been established as a specific cell-surface marker for murine macrophages. This study aimed to identify the role of F4/80 in osteoclastogenesis. Using mouse bone marrow-derived macrophages (BMMs), we observed that the mRNA level of F4/80 was dramatically reduced as these cells differentiated into osteoclasts. Furthermore, osteoclastogenesis was decreased in F4/80^high BMMs compared to F4/80^-/low BMMs. The inhibitory effect of F4/80 was associated with decreased expression of nuclear factor of activated T cells, cytoplasmic 1 (NFATc1). Ectopic overexpression of a constitutively active form of NFATc1 rescued the anti-osteoclastogenic effect of F4/80 completely, suggesting that the anti-osteoclastogenic effect of F4/80 was mainly due to reduction in NFATc1 expression. As an underlying mechanism, we demonstrated that the presence of F4/80 abrogated the effect of RANKL on the phosphorylation of CREB and activated the expression of IFN-β, which are restored by cyclic AMP. Collectively, our results demonstrate that the presence of F4/80 suppresses RANKL-induced osteoclastogenesis by impairing the expression of NFATc1 via CREB and IFN-β. Therefore, F4/80 may hold therapeutic potential for bone destructive diseases.

Maintaining postreproductive health: A care pathway from the European Menopause and Andropause Society (EMAS)

This position statement from the European Menopause and Andropause Society (EMAS) provides a care pathway for the maintenance of women's health during and after the menopause. It is designed for use by all those involved in women's health. It covers assessment, screening for diseases in later life, treatment and follow-up. Strategies need to be optimised to maintain postreproductive health, in part because of increased longevity. They encompass optimising diet and lifestyle, menopausal hormone therapy and non-estrogen-based treatment options for climacteric symptoms and skeletal conservation, personalised to individual needs.

A novel pyrazole derivative protects from ovariectomy-induced osteoporosis through the inhibition of NADPH oxidase

Osteoclast cells (OCs) are differentiated from bone marrow-derived macrophages (BMMs) by activation of receptor activator of nuclear factor κB (NF-κB) ligand (RANKL). Activation of NADPH oxidase (Nox) isozymes is involved in RANKL-dependent OC differentiation, implicating Nox isozymes as therapeutic targets for treatment of osteoporosis. Here, we show that a novel pyrazole derivative, Ewha-18278 has high inhibitory potency on Nox isozymes. Blocking the activity of Nox with Ewha-18278 inhibited the responses of BMMs to RANKL, including reactive oxygen species (ROS) generation, activation of mitogen-activated protein (MAP) kinases and NF-κB, and OC differentiation. To evaluate the anti-osteoporotic function of Ewha-18278, the derivative was applied to estrogen-deficient ovariectomized (OVX) ddY mice. Oral administration of Ewha-18278 (10 mg/kg/daily, 4 weeks) into the mice recovered bone mineral density, trabecular bone volume, trabecular bone length, number and thickness, compared to control OVX ddY mice. Moreover, treatment of OVX ddY mice with Ewha-18278 increased bone strength by increasing cortical bone thickness. We provide that Ewha-18278 displayed Nox inhibition and blocked the RANKL-dependent cell signaling cascade leading to reduced differentiation of OCs. Our results implicate Ewha-18278 as a novel therapeutic agent for the treatment of osteoporosis.

Interplay between CaSR and PTH1R signaling in skeletal development and osteoanabolism

Parathyroid hormone (PTH)-related peptide (PTHrP) controls the pace of pre- and post-natal growth plate development by activating the PTH1R in chondrocytes, while PTH maintains mineral and skeletal homeostasis by modulating calciotropic activities in kidneys, gut, and bone. The extracellular calcium-sensing receptor (CaSR) is a member of family C, G protein-coupled receptor, which regulates mineral and skeletal homeostasis by controlling PTH secretion in parathyroid glands and Ca(2+) excretion in kidneys. Recent studies showed the expression of CaSR in chondrocytes, osteoblasts, and osteoclasts and confirmed its non-redundant roles in modulating the recruitment, proliferation, survival, and differentiation of the cells. This review emphasizes the actions of CaSR and PTH1R signaling responses in cartilage and bone and discusses how these two signaling cascades interact to control growth plate development and maintain skeletal metabolism in physiological and pathological conditions. Lastly, novel therapeutic regimens that exploit interrelationship between the CaSR and PTH1R are proposed to produce more robust osteoanabolism.

Switching of oral bisphosphonates to denosumab in chronic glucocorticoid users: a 12-month randomized controlled trial

OBJECTIVES

To evaluate the effect of switching from oral bisphosphonates to denosumab on bone mineral density (BMD) in long-term glucocorticoid users.

METHODS

Adult patients who were receiving long-term prednisolone (≥2.5 mg/day for ≥1 year) and oral bisphosphonates (≥2 years) were recruited. Participants were randomized to either continue oral bisphosphonates or switch to denosumab (60 mg subcutaneously every 6 months) for 12 months. Serial BMD (lumbar spine, hip) and bone turnover markers (serum osteocalcin, P1NP, β-CTX) were measured.

RESULTS

42 women were recruited (age 54.7±12.9 years; 21 shifted to denosumab and 21 continued on bisphosphonates). The duration of prednisolone therapy was 101±66.3 months and the daily dose was 4.4±2.1 mg. Baseline demographic data, osteoporosis risk factors, and BMD at various sites were similar between the two groups of patients. At month 12, BMD of the spine and hip increased by +3.4±0.9% (p=0.002) and +1.4±0.6% (p=0.03), respectively, in the denosumab group; whereas the corresponding change was +1.5±0.4% (p=0.001) and +0.80±0.5% (p=0.12) in the bisphosphonate group. The spinal BMD at month 12 was significantly higher in the denosumab than bisphosphonate group after adjustment for baseline BMD and β-CTX values, and other confounding factors (p=0.01). Bone turnover markers (β-CTX and P1NP) were more strongly suppressed by denosumab than the bisphosphonates. Minor infections were more common in denosumab-treated patients while other adverse events occurred at similar frequencies between the two groups.

CONCLUSIONS

In patients receiving long-term glucocorticoids, switching from oral bisphosphonates to denosumab resulted in greater gain of the spinal BMD and suppression of bone turnover markers after 12 months of therapy. The results have to be confirmed by a larger clinical trial with fracture as endpoint.

Arthritogenic alphaviruses: new insights into arthritis and bone pathology

Arthritogenic alphaviral infection begins as a febrile illness and often progresses to joint pain and rheumatic symptoms that are described as polyarthritis. Alphaviral arthritis and classical arthritides share many similar cellular and immune mediators involved in their pathogenesis. Recent in vitro and in vivo evidence suggests that bone loss resulting from increased expression of bone resorption mediators may accompany alphaviral infection. In addition, several longitudinal studies have reported more severe and delayed recovery of alphaviral disease in patients with pre-existing arthritic conditions. This review aims to provide insights into alphavirus-induced bone loss and focuses on aspects of disease exacerbation in patients with underlying arthritis and on possible therapeutic targets.

Andrographolide suppresses RANKL-induced osteoclastogenesis in vitro and prevents inflammatory bone loss in vivo

BACKGROUND AND PURPOSE

Osteoclasts play a pivotal role in diseases such as osteoporosis, rheumatoid arthritis and tumour bone metastasis. Thus, searching for natural compounds that may suppress osteoclast formation and/or function is promising for the treatment of osteoclast-related diseases. Here, we examined changes in osteoclastogenesis and LPS-induced osteolysis in response to andrographolide (AP), a diterpenoid lactone isolated from the traditional Chinese and Indian medicinal plant Andrographis paniculata.

EXPERIMENTAL APPROACH

Effects of AP on osteoclast differentiation and bone resorption were measured in vitro. Western blots and RT-PCR techniques were used to examine the underlying molecular mechanisms. The bone protective activity of AP in vivo was assessed in a mouse model of osteolysis.

KEY RESULTS

AP concentration-dependently suppressed RANKL-mediated osteoclast differentiation and bone resorption in vitro and reduced the expression of osteoclast-specific markers, including tartrate-resistant acid phosphatase, calcitonin receptors and cathepsin K. Further molecular analysis revealed that AP impaired RANKL-induced NF-κB signalling by inhibiting the phosphorylation of TGF-β-activated kinase 1, suppressing the phosphorylation and degradation of IκBα, and subsequently preventing the nuclear translocation of the NF-κB p65 subunit. AP also inhibited the ERK/MAPK signalling pathway without affecting p38 or JNK signalling.

CONCLUSIONS AND IMPLICATIONS

AP suppressed RANKL-induced osteoclastogenesis through attenuating NF-κB and ERK/MAPK signalling pathways in vitro, thus preventing bone loss in vivo. These data indicated that AP is a promising natural compound for the treatment of osteoclast-related bone diseases.

Decreasing incidence of femoral neck fractures in the Medicare population

This study was designed to evaluate trends in incidence and treatment patterns for intracapsular hip fractures and to evaluate risk factors for complications and mortality. Patients with an intracapsular hip fracture who underwent internal fixation, hemiarthroplasty, or total hip arthroplasty (THA) were identified from a 5% nationwide sample of Medicare data (1998-2007). The authors identified 41,053 patients with intracapsular hip fractures between 1998 and 2007. The number of intracapsular hip fractures treated with internal fixation, hemiarthroplasty, or THA decreased by 21.8%, from 4602 in 1998 to 3601 in 2007. In 2007, 54.3% of patients with an intracapsular hip fracture were treated with hemiarthroplasty, compared with 41.2% who were treated with internal fixation and 4.5% who were treated with THA. Compared with internal fixation, hemiarthroplasty had higher adjusted risks of dislocation (+98%) and infection (+53%) at 90 days and higher rates of death (+8%) and reoperation (+33%) at 1 year. Patients who underwent THA had a higher risk of complications at 90 days compared with those who underwent hemiarthroplasty, with 114%, 39%, and 123% greater risk of dislocation, deep venous thrombosis, and mechanical complications, respectively. At 1 year, patients treated with THA had a 42% lower mortality risk and an 85% lower risk of reoperation compared with those who underwent internal fixation. Primary THA is performed more often in younger patients with fewer comorbidities. The incidence of intracapsular hip fracture decreased by 21.8% over the past decade. This decrease is likely the result of multiple factors, most significantly increased awareness and medical management of osteoporosis.

Salvia miltiorrhiza: an ancient Chinese herbal medicine as a source for anti-osteoporotic drugs

ETHNOPHARMACOLOGICAL RELEVANCE

Red sage (Salvia miltiorrhiza Bunge), also known as Danshen in Chinese, has been used historically and is currently exploited in combination with other herbs to treat skeletal diseases in traditional Chinese medicine (TCM). With the advance of modern analytical technology, a multitude of bone-targeting, pharmaceutically active, compounds has been isolated and characterized from various sources of TCM including those produced in Salvia miltiorrhiza root. The aim of the review is to provide a comprehensive overview about the historical TCM interpretation of the action of Salvia miltiorrhiza in osteoporosis, its use clinical trials, its main phytochemical constituents, and its action on bone-resorptive and bone formation-stimulating mechanisms in in vitro and in vivo studies.

MATERIALS AND METHODS

Literature sources used were Pubmed, CNKI.net, Cqvip.com, PubChem, and the Web of Science. For the inquiry, keywords such as Salvia, danshen, osteoporosis, bone, osteoclast and osteoblast were used in various combinations. About 130 research papers and reviews were consulted.

RESULTS

In TCM, the anti-osteopororotic effect of Salvia miltiorrhiza is ascribed to its action on liver and blood stasis as main therapeutic targets defining osteoporosis. 36 clinical trials were identified which used Salvia miltiorrhiza in combination with other herbs and components to treat post-menopausal, senile, and secondary osteoporosis. On average the trials were characterized by high efficacy (>80%) and low toxicity problems. However, various limitations such as small patient samples, short treatment duration, frequent lack of detailed numerical data, and no clear endpoints must be taken into consideration. To date, more than 100 individual compounds have been isolated from this plant and tested in various animal models and biochemical assays. Compounds display anti-resorptive and bone formation-stimulating features targeting different pathways in the bone remodeling cycle. Pathways affected include the activation of osteoblasts, the modulation of osteoclastogenesis, and the inhibition of collagen degradation by cathepsin K.

CONCLUSIONS

The inclusion of Salvia miltiorrhiza in more than 30% of all herbal clinical trials successfully targeting osteoporosis has stimulated significant interest in the identification and characterization of individual constituents of this herb. The review highlights the anti-osteoporotic potential of Salvia miltiorrhiza in clinical applications and the potential of the herb to provide potent compounds targeting specific pathways in bone resorption and bone formation.

Phloretin promotes osteoclast apoptosis in murine macrophages and inhibits estrogen deficiency-induced osteoporosis in mice

Bone-remodeling imbalance induced by increased osteoclast formation and bone resorption is known to cause skeletal diseases such as osteoporosis. The reduction of estrogen levels at menopause is one of the strongest risk factors developing postmenopausal osteoporosis. This study investigated osteoprotective effects of the dihydrochalcone phloretin found in apple tree leaves on bone loss in ovariectomized (OVX) C57BL/6 female mice as a model for postmenopausal osteoporosis. OVX demoted bone mineral density (BMD) of mouse femurs, reduced serum 17β-estradiol level and enhanced serum receptor activator of NF-κB ligand (RANKL)/osteoprotegerin ratio with uterine atrophy. Oral administration of 10 mg/kg phloretin to OVX mice for 8 weeks improved such effects, compared to sham-operated mice. Phloretin attenuated TRAP activity and cellular expression of β3 integrin and carbonic anhydrase II augmented in femoral bone tissues of OVX mice. This study further examined that osteogenic activity of phloretin in RANKL-differentiated Raw 264.7 macrophages into mature osteoclasts. Phloretin at 1-20 μM stimulated Smac expression and capase-3 activation concurrently with nuclear fragmentation of multi-nucleated osteoclasts, indicating that this compound promoted osteoclast apoptosis. Consistently, phloretin enhanced bcl-2 induction but diminished bax expression. Furthermore, phloretin activated ASK-1-diverged JNK and p38 MAPK signaling pathways in mature osteoclasts, whereas it dose-dependently inhibited the RANKL-stimulated activation of ERK. Therefore, phloretin manipulated ASK-1-MAPK signal transduction leading to transcription of apoptotic genes. Phloretin was effective in preventing estrogen deficiency-induced osteoclastogenic resorption.

Periprosthetic bone loss: diagnostic and therapeutic approaches

Total joint replacement surgery is being performed on an increasingly large part of the population. Clinical longevity of implants depends on their osseointegration, which is influenced by the load, the characteristics of the implant and the bone-implant interface, as well as by the quality and quantity of the surrounding bone. Aseptic loosening due to periprosthetic osteolysis is the most frequent known cause of implant failure. Wear of prosthetic materials results in the formation of numerous particles of debris that cause a complex biological response. Dual-energy X-ray Absorptiometry (DXA) is regarded as an accurate method to evaluate Bone Mineral Density (BMD) around hip or knee prostheses. Further data may be provided by a new device, the Bone Microarchitecture Analysis (BMA), which combines bone microarchitecture quantification and ultra high resolution osteo-articular imaging. Pharmacological strategies have been developed to prevent bone mass loss and to extend implant survival. Numerous trials with bisphosphonates show a protective effect on periprosthetic bone mass, up to 72 months after arthroplasty. Strontium ranelate has been demonstrated to increase the osseointegration of titanium implants in treated animals with improvement of bone microarchitecture and bone biomaterial properties.

Radiological and pathological characteristics of giant cell tumor of bone treated with denosumab

Abstract

We describe a case of giant cell tumor of the proximal tibia with skip bone metastases of the ipsilateral femur in a 20-year-old man. After the neoadjuvant treatment with denosumab, plain radiographs and computed tomography showed marked osteosclerosis and sclerotic rim formation, and ¹⁸F-FDG PET/CT showed a decreased standardized uptake value, whereas magnetic resonance imaging showed diffuse enhancement of the tumor, nearly the same findings as those at pretreatment. Pathological findings of the surgical specimen after the denosumab treatment showed benign fibrous histiocytoma-like features with complete disappearance of both mononuclear stromal cells and multinuclear osteoclast-like giant cells.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1090602085125068

Current perspectives on the etiology and manifestation of the "silent" component of the Female Athlete Triad

The Female Athlete Triad (Triad) represents a syndrome of three interrelated conditions that originate from chronically inadequate energy intake to compensate for energy expenditure; this environment results in insufficient stored energy to maintain physiological processes, a condition known as low energy availability. The physiological adaptations associated with low energy availability, in turn, contribute to menstrual cycle disturbances. The downstream effects of both low energy availability and suppressed estrogen concentrations synergistically impair bone health, leading to low bone mineral density, compromised bone structure and microarchitecture, and ultimately, a decrease in bone strength. Unlike the other components of the Triad, poor bone health often does not have overt symptoms, and therefore develops silently, unbeknownst to the athlete. Compromised bone health among female athletes increases the risk of fracture throughout the lifespan, highlighting the long-term health consequences of the Triad. The purpose of this review is to examine the current state of Triad research related to the third component of the Triad, ie, poor bone health, in an effort to summarize what we know, what we are learning, and what remains unknown.

New and emerging treatments for osteoarthritis management: will the dream come true with personalized medicine?

INTRODUCTION

Osteoarthritis (OA) is a dynamic process involving the main tissues of the joint for which a global approach should be considered. No disease-modifying OA drug (DMOAD) has yet been approved. New therapeutic strategies are needed that would be cost effective by reducing the need for pharmacological interventions and surgical management while targeting specific pathways leading to OA. The treatment landscape of OA is about to change based on new agents having shown some structural effects and emerging therapies with DMOAD effects.

AREAS COVERED

In this review based on a Medline (via PubMed) search, promising new and emerging therapies with a potential structural effect (DMOAD) will be discussed including growth factors, platelet-rich plasma, autologous stem cells, bone remodeling modulators, cytokine inhibition, gene therapy, and RNA interference.

EXPERT OPINION

DMOAD development should focus on targeting some phenotypes of OA patients evidenced with sensitive techniques such as magnetic resonance imaging, as a single treatment will unlikely be appropriate for all OA patients. This will allow the development of DMOADs based on personalized medicine. An exciting new era in DMOAD development is within reach, provided future clinical trials are sufficiently powered, systematically designed, use the appropriate evaluation tools, and target the appropriate categories of OA patients.

Postmenopausal osteoporosis

PURPOSE OF REVIEW

The aim of this study is to provide a thorough updated review of the diagnosis and treatment of postmenopausal osteoporosis.

RECENT FINDINGS

There have been several important findings in the field of postmenopausal osteoporosis over the past 1-2 years. Fewer morphometric vertebral fractures were found in women treated for 6 years with zoledronic acid compared with those who stopped treatment after 3 years. Longer duration of bisphosphonate therapy is associated with a higher risk of atypical femur fractures. Combination therapy with teriparatide and denosumab appears to increase bone mineral density to a greater extent than either therapy alone in postmenopausal women at high risk for fracture. There are several novel therapies under investigation for the treatment of osteoporosis, which are in various stages of development. Nonadherence to osteoporosis therapies continues to be a major problem in clinical practice.

SUMMARY

There are numerous effective pharmacologic treatment options for postmenopausal osteoporosis. Bisphosphonate drug holidays continue to be an area of significant debate.