Epiberberine inhibits bone metastatic breast cancer-induced osteolysis

ETHNOPHARMACOLOGICAL RELEVANCE

The anti-tumor related diseases of Coptidis Rhizoma (Huanglian) were correlated with its traditional use of removing damp-heat, clearing internal fire, and counteracting toxicity. In the recent years, Coptidis Rhizoma and its components have drawn extensive attention toward their anti-tumor related diseases. Besides, Coptidis Rhizoma is traditionally used as an anti-inflammatory herb. Epiberberine (EPI) is a significant alkaloid isolated from Coptidis Rhizoma, and exhibits multiple pharmacological activities including anti-inflammatory. However, the effect of epiberberine on breast cancer and the inflammatory factors of metastatic breast cancer-induced osteolysis has not been demonstrated clearly.

AIM OF THE STUDY

Bone metastatic breast cancer can lead to osteolysis via inflammatory factors-induced osteoclast differentiation and function. In this study, we try to analyze the effect of epiberberine on breast cancer and the inflammatory factors of metastatic breast cancer-induced osteolysis.

METHODS

To evaluate whether epiberberine could suppress bone metastatic breast cancer-induced osteolytic damage, healthy female Balb/c mice were intratibially injected with murine triple-negative breast cancer 4T1 cells. Then, we examined the inhibitory effect and underlying mechanism of epiberberine on breast cancer-induced osteoclastogenesis in vitro. Xenograft assay was used to study the effect of epiberberine on breast cancer cells in vivo. Moreover, we also studied the inhibitory effects and underlying mechanisms of epiberberine on RANKL-induced osteoclast differentiation and function in vitro.

RESULTS

The results show that epiberberine displayed potential therapeutic effects on breast cancer-induced osteolytic damage. Besides, our results show that epiberberine inhibited breast cancer cells-induced osteoclast differentiation and function by inhibiting secreted inflammatory cytokines such as IL-8. Importantly, we found that epiberberine directly inhibited RANKL-induced differentiation and function of osteoclast without cytotoxicity. Mechanistically, epiberberine inhibited RANKL-induced osteoclastogensis via Akt/c-Fos signaling pathway. Furthermore, epiberberine combined with docetaxel effectively protected against bone loss induced by metastatic breast cancer cells.

CONCLUSIONS

Our findings suggested that epiberberine may be a promising natural compound for treating bone metastatic breast cancer-induced osteolytic damage by inhibiting IL-8 and is worthy of further exploration in preclinical and clinical trials.

Calycosin alleviates titanium particle-induced osteolysis by modulating macrophage polarization and subsequent osteogenic differentiation

Periprosthetic osteolysis (PPO) caused by wear particles is one of the leading causes of implant failure after arthroplasty. Macrophage polarization imbalance and subsequent osteogenic inhibition play a crucial role in PPO. Calycosin (CA) is a compound with anti-inflammatory and osteoprotective properties. This study aimed to evaluate the effects of CA on titanium (Ti) particle-induced osteolysis, Ti particle-induced macrophage polarization and subsequent osteogenic deficits, and explore the associated signalling pathways in a Ti particle-stimulated calvarial osteolysis mouse model using micro-CT, ELISA, qRT-PCR, immunofluorescence and western blot techniques. The results showed that CA alleviated inflammation, osteogenic inhibition and osteolysis in the Ti particle-induced calvarial osteolysis mouse model in vivo. In vitro experiments showed that CA suppressed Ti-induced M1 macrophage polarization, promoted M2 macrophage polarization and ultimately enhanced osteogenic differentiation of MC3T3-E1 cells. In addition, CA alleviated osteogenic deficits by regulating macrophage polarization homeostasis via the NF-κB signalling pathway both in vivo and in vitro. All these findings suggest that CA may prove to be an effective therapeutic agent for wear particle-induced osteolysis.

Inhibitory effects of norcantharidin on titanium particle-induced osteolysis, osteoclast activation and bone resorption via MAPK pathways

Wear particles generated from the surface of implanted prostheses can lead to peri-implant osteolysis and subsequent aseptic loosening. In the inflammatory environment, extensive formation and activation of osteoclasts are considered the underlying cause of peri-implant osteolysis. Current medications targeting osteoclasts for the treatment of particle-induced bone resorption are not ideal due to significant side effects. Therefore, there is an urgent need to develop more effective drugs with fewer side effects. Norcantharidin (NCTD), a derivative of cantharidin extracted from blister beetles, is currently primarily used for the treatment of solid tumors in clinical settings. However, the potential role of NCTD in treating aseptic loosening of the prosthesis has not been reported. In this study, the in vitro results demonstrated that NCTD could effectively inhibit the formation of osteoclasts and bone resorption induced by the RANKL. Consistently, NCTD strongly inhibited RANKL-induced mRNA and protein levels of c-Fos and NFATc1, concomitant with reduced expression of osteoclast specific genes including TRAP, CTR and CTSK. The in vivo data showed that NCTD exerted significant protective actions against titanium particle-induced inflammation and subsequent osteolysis. The molecular mechanism investigation revealed that NCTD could suppress the activations of RANKL-induced MAPK (p38, ERK). Overall, these findings support the potential use of NCTD for the treatment of aseptic loosening following total joint arthroplasty.

Classical cannabinoid receptors as target in cancer-induced bone pain: a systematic review, meta-analysis and bioinformatics validation

To test the hypothesis that genetic and pharmacological modulation of the classical cannabinoid type 1 (CB1) and 2 (CB2) receptors attenuate cancer-induced bone pain, we searched Medline, Web of Science and Scopus for relevant skeletal and non-skeletal cancer studies from inception to July 28, 2022. We identified 29 animal and 35 human studies. In mice, a meta-analysis of pooled studies showed that treatment of osteolysis-bearing males with the endocannabinoids AEA and 2-AG (mean difference [MD] - 24.83, 95% confidence interval [95%CI] - 34.89, - 14.76, p < 0.00001) or the synthetic cannabinoid (CB) agonists ACPA, WIN55,212-2, CP55,940 (CB1/2-non-selective) and AM1241 (CB2-selective) (MD - 28.73, 95%CI - 45.43, - 12.02, p = 0.0008) are associated with significant reduction in paw withdrawal frequency. Consistently, the synthetic agonists AM1241 and JWH015 (CB2-selective) increased paw withdrawal threshold (MD 0.89, 95%CI 0.79, 0.99, p < 0.00001), and ACEA (CB1-selective), AM1241 and JWH015 (CB2-selective) reduced spontaneous flinches (MD - 4.85, 95%CI - 6.74, - 2.96, p < 0. 00001) in osteolysis-bearing male mice. In rats, significant increase in paw withdrawal threshold is associated with the administration of ACEA and WIN55,212-2 (CB1/2-non-selective), JWH015 and AM1241 (CB2-selective) in osteolysis-bearing females (MD 8.18, 95%CI 6.14, 10.21, p < 0.00001), and treatment with AM1241 (CB2-selective) increased paw withdrawal thermal latency in males (mean difference [MD]: 3.94, 95%CI 2.13, 5.75, p < 0.0001), confirming the analgesic capabilities of CB1/2 ligands in rodents. In human, treatment of cancer patients with medical cannabis (standardized MD - 0.19, 95%CI - 0.35, - 0.02, p = 0.03) and the plant-derived delta-9-THC (20 mg) (MD 3.29, CI 2.24, 4.33, p < 0.00001) or its synthetic derivative NIB (4 mg) (MD 2.55, 95%CI 1.58, 3.51, p < 0.00001) are associated with reduction in pain intensity. Bioinformatics validation of KEGG, GO and MPO pathway, function and process enrichment analysis of mouse, rat and human data revealed that CB1 and CB2 receptors are enriched in a cocktail of nociceptive and sensory perception, inflammatory, immune-modulatory, and cancer pathways. Thus, we cautiously conclude that pharmacological modulators of CB1/2 receptors show promise in the treatment of cancer-induced bone pain, however further assessment of their effects on bone pain in genetically engineered animal models and cancer patients is warranted.

Risk factors associated with prognosis of patients with medication-related osteonecrosis of the jaw

OBJECTIVES

Medication-related osteonecrosis of the jaw (MRONJ) is a severe adverse effect of antiresorptive and/or antiangiogenic agents. As the treatment application for MRONJ is controversial, we aimed to identify the risk factors for poor prognosis and to help determine appropriate management.

METHODS

This study included 119 patients. Relevant clinical data were obtained for all the patients. In computed tomography images, osteosclerosis, osteolysis, cortical perforation (buccal or lingual), periosteal reaction, and sequestration were evaluated.

RESULTS

Multivariate analyses showed statistically significant associations between poor prognosis in patients with MRONJ and conservative treatment alone (hazard ratio [HR] 1.89), osteolysis (HR 4.67), and the absence of sequestration (HR 5.33).

CONCLUSIONS

Conservative treatment alone without clear objectives needs to be avoided, and osteolytic change could be the criteria for surgical intervention. As the boundary between the lesion and vital bone is indistinct, we recommend extensive surgery in cases with unpredictable sequestration.

Kaempferol attenuates wear particle-induced inflammatory osteolysis via JNK and p38-MAPK signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Wear particle-induced inflammatory osteoclast activation is a master contributor to periprosthetic osteolysis, which can cause pathological bone loss and destruction. Hence, inhibiting inflammation and osteoclastogenesis is an important strategy for preventing wear particle-induced osteolysis. To date, there are no FDA-approved non-surgical pharmacotherapies for arresting periprosthetic osteolysis. Kaempferol (KAE), a natural flavonol abundant in many traditional Chinese herbal medicines, has been shown to have protective effects against inflammatory bone diseases such as rheumatoid arthritis, but no previous study has evaluated the effects of KAE on wear particle-induced osteolysis.

AIM OF THE STUDY

The study aimed to investigate the effects of KAE on wear particle-induced inflammatory osteolysis and osteoclast activation, and further explore the underlying mechanisms.

MATERIALS AND METHODS

TiAl6V4 metal particles (TiPs) were retrieved from the prosthesis of patients who underwent revision hip arthroplasty due to aseptic loosening. A mouse calvarial osteolysis model was used to investigate the effects of KAE on wear particle-induced inflammatory osteolysis in vivo. Primary bone marrow-derived macrophages (BMMs) were used to explore the effects of KAE on osteoclast differentiation and bone-resorbing activity as well as the underlying mechanisms in vitro.

RESULTS

In the present study, we found that KAE alleviated wear particle-induced inflammatory bone loss in vivo and inhibited osteoclast differentiation and function in vitro. Furthermore, we revealed that KAE exerted anti-osteoclastogenic effects by downregulating JNK and p38-MAPK signaling as well as the downstream NFATc1 expression.

CONCLUSIONS

KAE is an alternative therapeutic agent for preventing and treating periprosthetic osteolysis and aseptic loosening.

Sesamin inhibits RANKL-induced osteoclastogenesis and attenuates LPS-induced osteolysis via suppression of ERK and NF-κB signalling pathways

Infection by bacterial products in the implant and endotoxin introduced by wear particles activate immune cells, enhance pro-inflammatory cytokines production, and ultimately promote osteoclast recruitment and activity. These factors are known to play an important role in osteolysis as well as potential targets for the treatment of osteolysis. Sesamin has been shown to have a variety of biological functions, such as inhibiting inflammation, anti-tumour and involvement in the regulation of fatty acid and cholesterol metabolism. However, the therapeutic effect of sesamin on osteolysis and its mechanism remain unclear. Present studies shown that in the condition of in vitro, sesamin could inhibit osteoclastogenesis and bone resorption, as well as suppressing the expression of osteoclast-specific genes. Further studies on the mechanism suggest that the effect of sesamin on human osteoclasts was mediated by blocking the ERK and NF-κB signalling pathways. Besides, sesamin was found to be effective in treating LPS-induced osteolysis by decreasing the production of pro-inflammatory cytokines and inhibiting osteoclastogenesis in vivo. Sesamin was non-toxic to heart, liver, kidney, lung and spleen. Therefore, sesamin is a promising phytochemical agent for the therapy of osteolysis-related diseases caused by inflammation and excessive osteoclast activation.

The JNK signaling pathway against titanium-particle-induced osteoclastogenesis and bone resorption in vivo

OBJECTIVE

The c-Jun N-terminal kinases (JNK) signaling pathway may be involved in the regulation of osteoclast development. The purpose of this investigation was to investigate whether SB600125, a JNK inhibitor, could attenuate titanium-particle-induced inflammatory osteolysis in vivo.

MATERIALS AND METHODS

A total of 45 mice were randomly divided into a Sham group, a Titanium group, and a Titanium + JNK inhibitor group, 15 mice per group. After establishing an air pouch bone graft model, we injected phosphate-buffered saline (PBS), titanium particles, or titanium particles + JNK inhibitor into the air pouch of the three groups. The pouch membranes containing bone implants were taken for morphological and molecular analysis 14 days after the mice were sacrificed.

RESULTS

General morphological structure observation results, Hematoxylin and Eosin (H&E)-Stained Sections, anti-tartaric acid phosphatase (TRAP) staining, and the transmission electron microscope showed that SB600125, by inhibiting the expression of JNK, attenuated titanium particle-induced inflammatory osteolysis (p<0.05). Immunohistochemical appearance results and reverse transcription-polymerase chain reaction (RT-PCR) results showed SB600125 reduced expression of IL-6, and TNF-α in osteolytic sites stimulated with wear debris (p<0.05). The Western blot results showed the expression of the p-JNK protein in the titanium particle + SB600125 group was significantly reduced compared to the titanium particle stimulation group (p<0.05).

CONCLUSIONS

Interfering with the JNK signaling pathway may be beneficial in reducing osteolysis, providing a therapeutic target for preventing and treating aseptic loosening caused by debris-induced inflammatory osteolysis.

Morphine-induced osteolysis and hypersensitivity is mediated through toll-like receptor-4 in a murine model of metastatic breast cancer

ABSTRACT

The propensity for breast cancer to metastasize to bone is coupled to the most common complaint among breast cancer patients: bone pain. Classically, this type of pain is treated using escalating doses of opioids, which lack long-term efficacy due to analgesic tolerance, opioid-induced hypersensitivity, and have recently been linked to enhanced bone loss. To date, the molecular mechanisms underlying these adverse effects have not been fully explored. Using an immunocompetent murine model of metastatic breast cancer, we demonstrated that sustained morphine infusion induced a significant increase in osteolysis and hypersensitivity within the ipsilateral femur through the activation of toll-like receptor-4 (TLR4). Pharmacological blockade with TAK242 (resatorvid) as well as the use of a TLR4 genetic knockout ameliorated the chronic morphine-induced osteolysis and hypersensitivity. Genetic MOR knockout did not mitigate chronic morphine hypersensitivity or bone loss. In vitro studies using RAW264.7 murine macrophages precursor cells demonstrated morphine-enhanced osteoclastogenesis that was inhibited by the TLR4 antagonist. Together, these data indicate that morphine induces osteolysis and hypersensitivity that are mediated, in part, through a TLR4 receptor mechanism.

Britanin inhibits titanium wear particle‑induced osteolysis and osteoclastogenesis

Wear particle‑induced osteolysis is a serious complication that occurs in individuals with titanium (Ti)‑based implants following long‑term usage due to loosening of the implants. The control of excessive osteoclast differentiation and inflammation is essential for protecting against wear particle‑induced osteolysis. The present study evaluated the effect of britanin, a pseudoguaianolide sesquiterpene isolated from Inula japonica, on osteoclastogenesis in vitro and Ti particle‑induced osteolysis in vivo. The effect of britanin was examined in the osteoclastogenesis of mouse bone marrow‑derived macrophages (BMMs) using TRAP staining, RT‑PCR, western blotting and immunocytochemistry. The protective effect of britanin was examined in a mouse calvarial osteolysis model and evaluated using micro‑CT and histomorphometry. Britanin inhibited osteoclast differentiation and F‑actin ring formation in the presence of macrophage colony‑stimulating factor and receptor activator of nuclear factor kB ligand in BMMs. The expression of osteoclast‑specific marker genes, including tartrate‑resistant acid phosphatase, cathepsin K, dendritic cell‑specific transmembrane protein, matrix metallopeptidase 9 and nuclear factor of activated T‑cells cytoplasmic 1, in the BMMs was significantly reduced by britanin. In addition, britanin reduced the expression of B lymphocyte‑induced maturation protein‑1, which is a transcriptional repressor of negative osteoclastogenesis regulators, including interferon regulatory factor‑8 and B‑cell lymphoma 6. Conversely, britanin increased the expression levels of anti‑oxidative stress genes, namely nuclear factor erythroid‑2‑related factor 2, NAD(P)H quinone oxidoreductase 1 and heme oxygenase 1 in the BMMs. Furthermore, the administration of britanin significantly reduced osteolysis in a Ti particle‑induced calvarial osteolysis mouse model. Based on these findings, it is suggested that britanin may be a potential therapeutic agent for wear particle‑induced osteolysis and osteoclast‑associated disease.

An unusual manifestation in a pediatric patient with MAFB mutation: Sacroiliitis in multicentric carpotarsal osteolysis syndrome

Multicentric carpotarsal osteolysis (MCTO) syndrome, is typically characterized by progressive bone resorption in especially carpal and tarsal bones, in addition to abnormal facial appearance and proteinuria. This disorder is caused by monoallelic pathogenic MAFB mutations, which result in excessive osteoclastogenesis via aberrant receptor activator of nuclear factor kappa-B ligand activation. Most cases are sporadic with de-novo mutations, and it is still unclear why carpal and tarsal bones are predominantly affected. The early phases of MCTO resemble juvenile idiopathic arthritis (JIA) with ankle and wrist swelling and pain, even with inflammatory changes in magnetic resonance imaging. Herein we report a pediatric patient, previously treated with antirheumatic drugs, and eventually diagnosed with MCTO. This case was a descriptive case with exophthalmos, significant proteinuria, and total loss of carpal and tarsal bones at the time of genetic diagnosis. Similar to the literature, our case had typical radiological findings despite methotrexate and anti-tumor necrosis factor-alpha treatment. However, while arthritis affecting joints other than wrists and ankles has not been reported so far in the literature, our case had bilateral sacroiliitis which completely resolved after adalimumab treatment. We cannot be sure if sacroiliitis was incidental or occurred as a component of the disease, nonetheless, we think that sharing our experience may lead to easy and early recognition of MCTO, with more knowledge on rare manifestations of MCTO, and thus we may be able to clarify the benefits of denosumab, which is the most promising agent in early phases of the disease.

Pogostone attenuates osteolysis in breast cancer by inhibiting the NF-kB and JNK signaling pathways of osteoclast

AIMS

Breast cancer is the most prevalent cancer in females, and approximately 70 % of all patients have evidence of metastatic bone disease, which substantially affects the quality of life and survival rate of breast cancer patients. Osteoporosis has become a global public health problem, and the abnormal activation of osteoclasts is the key to the progression of osteoporosis and the key to both diseases lies in the osteoclasts. Effective drug treatments are lacking and there is an urgent need to explore new drugs.

MATERIALS AND METHODS

We observed the effects of pogostone (PO) on osteoclast differentiation, bone resorption function and other indicators, and F-actin ring formation by using Trap staining, SEM and immunofluorescence, and further explored the targets of pogostone in regulating osteoclast differentiation and function using qPCR and Western Blot. In addition, we used CCK 8, Transwell, and flow cytometry to study the effects of pogostone on proliferation, invasion, migration, and apoptosis of MDA-MB-231 cells. Animal models were also constructed for in vivo validation.

KEY FINDINGS

Pogostone inhibits osteoclast differentiation, bone resorption, formation of F-actin ring, and the expression of specific genes by attenuated NF-kB degradation and phosphorylation of JNK. In vitro, pogostone suppresses invasion of breast cancer cells, migration, and promotes their apoptosis. In mouse models, pogostone attenuated osteoclast formation and bone resorption, blocked breast cancer cells migration, and supprsed breast cancer-induced osteolysis and ovariectomized (OVX)-mediated osteoporosis.

SIGNIFICANCE

These biological functions of pogostone make it a potential drug for treatment of breast cancer-associated bone metastasis in the future.

A Boy Safely Treated with Tyrosine Kinase Inhibitors for Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia with Osteolysis

A three-year-old boy with Philadelphia chromosome-positive B-cell precursor acute lymphoblastic leukemia (Ph+ALL) presented with an osteolytic lesion in his right upper arm. Tyrosine kinase inhibitors (TKIs) such as imatinib and dasatinib are an essential component throughout the course of treatment for Ph+ALL. However, TKIs are reported to affect the bone metabolism. In the treatment course of the current patient, the osteolytic lesion quickly improved despite the continuous use of TKIs, even during the concomitant use of corticosteroids. This suggests that TKIs can be safely given with concomitant corticosteroids to children with Ph+ALL, even when osteolytic lesions are present.

Multi-Targeting DKK1 and LRP6 Prevents Bone Loss and Improves Fracture Resistance in Multiple Myeloma

An imbalance between bone resorption and bone formation underlies the devastating osteolytic lesions and subsequent fractures seen in more than 90% of multiple myeloma (MM) patients. Currently, Wnt-targeted therapeutic agents that prevent soluble antagonists of the Wnt signaling pathway, sclerostin (SOST) and dickkopf-1 (DKK1), have been shown to prevent bone loss and improve bone strength in preclinical models of MM. In this study, we show increasing Wnt signaling via a novel anti-low-density lipoprotein receptor-related protein 6 (LRP6) antibody, which potentiates Wnt1-class ligand signaling through binding the Wnt receptor LRP6, prevented the development of myeloma-induced bone loss primarily through preventing bone resorption. When combined with an agent targeting the soluble Wnt antagonist DKK1, we showed more robust improvements in bone structure than anti-LRP6 treatment alone. Micro-computed tomography (μCT) analysis demonstrated substantial increases in trabecular bone volume in naïve mice given the anti-LRP6/DKK1 combination treatment strategy compared to control agents. Mice injected with 5TGM1eGFP murine myeloma cells had significant reductions in trabecular bone volume compared to naïve controls. The anti-LRP6/DKK1 combination strategy significantly improved bone volume in 5TGM1-bearing mice by 111%, which was also superior to anti-LRP6 single treatment; with similar bone structural changes observed within L4 lumbar vertebrae. Consequently, this combination strategy significantly improved resistance to fracture in lumbar vertebrae in 5TGM1-bearing mice compared to their controls, providing greater protection against fracture compared to anti-LRP6 antibody alone. Interestingly, these improvements in bone volume were primarily due to reduced bone resorption, with significant reductions in osteoclast numbers and osteoclast surface per bone surface demonstrated in 5TGM1-bearing mice treated with the anti-LRP6/DKK1 combination strategy. Importantly, Wnt stimulation with either single or combined Wnt-targeted agents did not exacerbate tumor activity. This work provides a novel approach of targeting both membrane-bound and soluble Wnt pathway components to provide superior skeletal outcomes in patients with multiple myeloma and other bone destructive cancers. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Treatment of Septic Tenosynovitis and Osteoarthritis in an American White Pekin (Anas platyrhynchos domesticus) with Repeated Intravenous Regional Limb Perfusion and Antibiotic-Impregnated Calcium Sulfate Beads

A 2-year-old female American white pekin (Anas platyrhynchos domesticus) was assessed for a 2-month history of chronic lameness and swelling involving the left leg. Radiographic images of the left leg showed soft tissue swelling of the digits and tarsometatarsus with osteolysis of the tarsometatarsal-phalangeal joint. A complete blood count revealed marked leukocytosis and hyperproteinemia. A Streptococcus species was isolated from a bacterial culture of fluid obtained from the left tarsometatarsal-phalangeal joint. Biweekly intravenous regional limb perfusions of the left leg with ampicillin-sulbactam and amikacin were performed on the patient. Despite initial improvement in left leg lameness and swelling, follow-up radiographic images showed progressive osteolysis of the tarsometatarsal-phalangeal joint and associated digits. Surgical placement of antibiotic-impregnated calcium sulfate beads into the left tarsometatarsal-phalangeal joint was next performed with concurrent, repeated intravenous regional limb perfusion using the same antibiotic. Following the placement of antibiotic-impregnated beads and continued intravenous regional limb perfusion, the duck had decreased lameness and swelling of the left leg. Repeated antibiotic treatment through intravenous regional limb perfusion and concurrent placement of antibiotic-impregnated calcium sulfate beads is a practical treatment option for complicated distal limb infections in avian species. This therapeutic protocol has great potential in treating aggressive distal leg infections in many avian species because regional limb perfusion alone may not penetrate the joint adequately to achieve complete resolution of infection.

Zingerone attenuates Ti particle-induced inflammatory osteolysis by suppressing the NF-κB signaling pathway in osteoclasts

Aseptic loosening caused by inflammatory osteolysis is one of the most frequent and serious long-term complications after total joint arthroplasty (TJA). Development of a new therapeutic drug is required due to the lack of effective therapy and serious adverse effects. This study aimed to explore the pharmacological properties of zingerone (ZO) in attenuating osteoclast-mediated periprosthetic osteolysis and how ZO modulates osteoclastogenesis. The nontoxic concentration of ZO was clarified by the CCK-8 method. Then, we explored the efficacy of ZO on suppressing osteoclast differentiation, F-actin ring formation, bone resorption, and NF-κB luciferase activity in vitro as well as osteoprotection in vivo. Polymerase chain reaction and western blotting were applied to detect the underlying mechanisms involved in osteoclastogenesis. ZO showed an obvious inhibitory effect on osteoclastogenesis and bone resorption in a dose-dependent manner by mainly suppressing the activation of NF-κB signaling pathways. Furthermore, ZO administration successfully attenuated titanium (Ti) particle-stimulated periprosthetic osteolysis and osteoporosis by regulating osteoclast formation. Our findings demonstrated the pharmacological properties of ZO in inhibiting osteoclast formation and function by downregulation of NF-κB signaling activation. As a result, these findings could be expected to provide a novel reagent for regulating inflammatory osteolysis caused by prosthetic loosening.

Bimetallic Metal-Organic Framework for Mitigating Aseptic Osteolysis

The disability rate of joint diseases can be reduced by the use of artificial joints, but joint loosening at a late state limits the lifespan and surgical efficacy of the joints. Wear particles can be recognized by macrophages and induce cells to produce reactive oxygen species (ROS) and inflammatory factors, causing persistent inflammation and decreased osteogenic activity, which ultimately leads to loosening of joint prostheses. Here, the platinum (Pt) nanozymes with excellent ROS scavenging and anti-inflammatory capabilities were encapsulated in zinc imidazolium zeolite framework-8 (ZIF-8), and then the osteogenic active element lanthanum (La) was introduced through ion exchange to finally construct a bimetallic metal-organic framework (Pt@ZIF-8@La). In vitro and in vivo experiments demonstrated that this multifunctional nanoplatform possessed the functions of efficient scavenging of ROS, immune regulation, and promotion of osteogenic differentiation. Meanwhile, the mechanism is explored that Pt@ZIF-8@La can also promote osteogenic mineralization by upregulating the ratio of the osteoprotegerin (OPG)/receptor activator of the NF-κB ligand (RANKL), which can achieve a synergistic therapeutic effect of immunomodulation and osteogenesis, thereby realizing the purpose of relieving aseptic osteolysis.

LY450139 Inhibited Ti-Particle-Induced Bone Dissolution via Suppressing Notch and NF-κB Signaling Pathways

Aseptic loosening of the prosthesis caused by wear-particle-induced osteolysis is a long-term complication and one of the most common reasons for the failure of joint implants. The primary cause of aseptic loosening of the prosthesis is overactive bone resorption caused by wear-particle-activated osteoclasts in both direct and indirect ways. Therefore, drugs that can inhibit differentiation and bone resorption of osteoclasts need investigation as a potential therapeutic strategy to prevent and treat peri-prosthetic osteolysis and thereby prolong the service life of the prosthesis. This study has verified the potential inhibitory effect of LY450139 on inflammatory osteolysis induced by titanium particles in a mice skull model. In addition, we found that LY450139 inhibited receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis, bone resorption, and podosomal actin belt formation in a dose-dependent manner without evidence of cytotoxicity in vitro. In addition, LY450139 significantly decreased the expression of osteoclast-specific markers, including TRAP, CTSK, V-ATPase d2, CTR, DC-STAMP, NFATc1, and the downstream target gene Hes1 in Notch signaling pathway. Further investigation of the molecular mechanism demonstrated that LY450139 inhibited the formation of osteoclasts via inhibition of the NF-κB and Notch signaling pathways. In summary, LY450139 inhibited the formation of RANKL-mediated osteoclasts via NF-κB and Notch signaling and inhibited Ti particle-induced inflammatory osteolysis in vivo. LY450139 is a potential targeted drug for the treatment of peri-prosthetic osteolysis and other osteolytic disease associated with overactive osteoclasts.

Siglec15 Checkpoint Blockade for Simultaneous Immunochemotherapy and Osteolysis Inhibition in Lung Adenocarcinoma Spinal Metastasis via a Hollow Nanoplatform

Low responsiveness to anti-programmed death-1/programmed death-ligand 1 (anti-PD-1/PD-L1) for solid tumors indicates the presence of other immunosuppressive pathways. Siglec15, a newly discovered immune checkpoint, has been reported to repress immune responses in the tumor microenvironment (TME) and regulate osteoclast differentiation. However, the role of Siglec15 in the treatment for bone metastasis remains unclear. Herein, Siglec15 shows significantly higher expression in lung adenocarcinoma spinal metastasis (LUAD-SM) than in para-cancerous spinal tissues and primary LUAD. Subsequently, a TME-responsive hollow MnO₂ nanoplatform (H-M) loaded with Siglec15 siRNA and cisplatin (H-M@siS15/Cis) is developed, and the surface is modified with an aspartic acid octapeptide (Asp⁸ ), thus allowing H-M to target spinal metastasis. High drug-loading capacity, good biocompatibility, effective tumor accumulation, and efficient Siglec15 silencing are demonstrated. Furthermore, the nanoparticles could reverse immunosuppression caused by tumor cells and tumor-associated macrophages (TAMs) and inhibit osteoclast differentiation via Siglec15 downregulation in vitro. In a LUAD-SM mouse model, H-M@siS15/Cis-Asp⁸ exhibits superior therapeutic efficacy via synergetic immunochemotherapy and osteolysis inhibition. Taken together, this single nanoplatform reveals the therapeutic potential of the new immune checkpoint Siglec15 in LUAD-SM and provides a strategy to treat this disease.

Expression Profiling of Selected Immune Genes and Trabecular Microarchitecture in Breast Cancer Skeletal Metastases Model: Effect of α-Tocopherol Acetate Supplementation

Breast cancer bone metastases (BCBM) result in serious skeletal morbidity. Although there have been important advances in cancer treatment methods such as surgery and chemotherapy, the complementary treatments, such as α-tocopherol acetate (ATA), still remain of key role via complementary and/or synergistic effects. The aim of this work was to study immune response in a rat model of BCBM due to Walker 256/B cells inoculation and the effect of ATA alone. Compared to the control group (CTRL), rat injected with Walker 256/B cells (5 × 10⁴) in the medullar cavity (W256 group) showed osteolytic damages with marked tumor osteolysis of both cancellous and trabecular bone as assessed by X-ray radiology, micro-computed tomography, and histology. Rats inoculated with Walker 256/B cells and treated with ATA (45 mg/kg BW, W256ATA group) presented marked less tumor osteolysis, less disturbance of Tb.Th and Tb.Sp associated with conversion of rods into plates, and increased structure model index and trabecular pattern factor (Tb.Pf). Elsewhere, 3D frequency distributions of Tb.Th and Tb.Sp were highly disturbed in metastatic W256 rats. Overexpression of some genes commonly associated with cancer and metastatic proliferation: COX-2, TNF-α, and pro-inflammatory interleukins 1 and 6 was outlined. ATA alleviated most of the Walker 256/B cells-induced microarchitectural changes in the target parameters without turning back to normal levels. Likewise, it alleviates the BCSM-induced overexpression of COX-2, TNF-α, IL-1, and IL-6. In silico approach showed that ATA bound these proteins with high affinities, which satisfactory explain its beneficial effects. In conclusion, BCBM is associated with bone microarchitectural disorders and an immune response characterized by an overexpression of some key role genes in cancer proliferation and invasion. ATA exerted favorable effects on trabecular bone distribution and morphology, which may involve the COX-2, TNF-α, and ILs pathways.

Piperlongumine Inhibits Titanium Particles-Induced Osteolysis, Osteoclast Formation, and RANKL-Induced Signaling Pathways

Wear particle-induced aseptic loosening is the most common complication of total joint arthroplasty (TJA). Excessive osteoclast formation and bone resorptive activation have been considered to be responsible for extensive bone destruction and prosthesis failure. Therefore, identification of anti-osteoclastogenesis agents is a potential therapy strategy for the treatment of aseptic loosening and other osteoclast-related osteolysis diseases. In the present study, we reported, for the first time, that piperlongumine (PL), a key alkaloid compound from Piper longum fruits, could significantly suppress the formation and activation of osteoclasts. Furthermore, PL effectively decreased the mRNA expressions of osteoclastic marker genes such as tartrate-resistant acid phosphatase (TRAP), calcitonin receptor (CTR), and cathepsin K (CTSK). In addition, PL suppressed the receptor activator of nuclear factor-κB ligand (RANKL)-induced activations of MAPKs (ERK, JNK and p38) and NF-κB, which down-regulated the protein expression of nuclear factor of activated T-cells cytoplasmic 1 (NFATc1). Using a titanium (Ti) particle-induced calvarial osteolysis model, we demonstrated that PL could ameliorate Ti particle-induced bone loss in vivo. These data provide strong evidence that PL has the potential to treat osteoclast-related diseases including periprosthetic osteolysis (PPO) and aseptic loosening.

Dendrobine attenuates osteoclast differentiation through modulating ROS/NFATc1/ MMP9 pathway and prevents inflammatory bone destruction

BACKGROUND

Osteolytic diseases share symptoms such as bone loss, fracture and pain, which are caused by over-activated osteoclasts. Targeting osteoclast differentiation has emerged as a therapeutic strategy clinically. Dendrobine is an alkaloid isolated from Chinese herb Dendrobium nobile, with knowing effects of analgesia and anti-inflammation. The roles of dendrobine on osteoclasts and osteolysis remain unclear.

PURPOSE

Herein, the possible roles of dendrobine in osteoclastogenesis, inflammatory osteolysis and the underlying mechanism were explored.

METHODS

Bone marrow-derived macrophages (BMMs) and RAW264.7 cells were employed to evaluate the roles of dendrobine on osteoclastogenesis, bone absorption and the underlying mechanism in vitro. LPS injection was used to cause inflammatory osteolysis in vivo.

RESULTS

Dendrobine repressed osteoclastogenesis, bone resorption induced by receptor activator of nuclear factor kappa B ligand (RANKL) in vitro. Mechanistically, dendrobine inhibited RANKL-upregulated intracellular (ROS), p-p38, c-Fos expression and nuclear factor of activated T cells (NFATc1) nuclear translocation. Osteoclastic genes were reduced, and among them matrix metalloproteinase 9 (MMP9) mRNA was dramatically blocked by dendrobine. Moreover, it substantially suppressed MMP9 protein expression during osteoclastogenesis in vitro. Accordingly, oral 20 mg/kg/day dendrobine was capable of preventing LPS-induced osteolysis with decreased osteoclasts in vivo.

CONCLUSION

Taken together, dendrobine suppresses osteoclastogenesis through restraining ROS, p38-c-Fos and NFATc1-MMP9 in vitro, thus attenuates inflammatory osteolysis in vivo. This finding supports the discover of dendrobine as a novel osteoclast inhibitor for impeding bone erosion in the future.

Interleukin-4 repairs wear particle induced osteolysis by modulating macrophage polarization and bone turnover

Periprosthetic osteolysis remains as a major complication of total joint replacement surgery. Modulation of macrophage polarization with interleukin-4 (IL-4) has emerged as an effective means to limit wear particle-induced osteolysis. The aim of this study was to evaluate the efficacy of local IL-4 delivery in treating preexisting particle-induced osteolysis. To this end, recently established 8 week modification of murine continuous femoral intramedullary particle infusion model was utilized. Subcutaneous infusion pumps were used to deliver polyethylene (PE) particles into mouse distal femur for 4 weeks to induce osteolysis. IL-4 was then added to the particle infusion for another 4 weeks. This delayed IL-4 treatment (IL-4 Del) was compared to IL-4 delivered continuously (IL-4 Cont) with PE particles from the beginning and to the infusion of particles alone for 8 weeks. Both IL-4 treatments were highly effective in preventing and repairing preexisting particle-induced bone loss as assessed by μCT. Immunofluorescence indicated a significant reduction in the number of F4/80 + iNOS + M1 macrophages and increase in the number of F4/80 + CD206 + M2 macrophages with both IL-4 treatments. Reduction in the number of tartrate resistant acid phosphatase + osteoclasts and increase in the amount of alkaline phosphatase (ALP) + osteoblasts was also observed with both IL-4 treatments likely explaining the regeneration of bone in these samples. Interesting, slightly more bone formation and ALP + osteoblasts were seen in the IL-4 Del group than in the IL-4 Cont group although these differences were not statistically significant. The study is a proof of principle that osteolytic lesions can be repaired via modulation of macrophage polarization.

A Targeted Erythrocyte Membrane-Encapsulated Drug-Delivery System with Anti-osteosarcoma and Anti-osteolytic Effects

Chemotherapy is one of the main treatment methods for osteosarcoma. However, conventional chemotherapy lacks targeting properties, and its long-term and extensive use will have serious side effects on patients. For this reason, a multifunctional nanodrug system (V-RZCD) targeting osteosarcoma was developed in this study. V-RZCD consists of two parts: (1) the core (ZCD), wherein calcium ions (Ca2+) and zoledronic acid (ZA) form a metal-organic framework for loading doxorubicin (DOX), and (2) the shell (V-R), a vascular endothelial growth factor (VEGF) ligand-modified red blood cell membrane nanovesicle. By targeting the VEGF, V-RZCD can specifically bind to the VEGF receptors that are highly expressed on the surface of osteosarcoma cells. Importantly, compared with free ZA and DOX, V-RZCD not only clearly inhibits the proliferation of osteosarcoma but also significantly inhibits osteolysis induced by osteosarcoma. In summary, V-RZCD represents a new way to treat osteosarcoma.

Local Sustained Delivery of Anti-IL-17A Antibodies Limits Inflammatory Bone Loss in Murine Experimental Periodontitis

Periodontal disease (PD) is a chronic destructive inflammatory disease of the tooth-supporting structures that leads to tooth loss at its advanced stages. Although the disease is initiated by a complex organization of oral microorganisms in the form of a plaque biofilm, it is the uncontrolled immune response to periodontal pathogens that fuels periodontal tissue destruction. IL-17A has been identified as a key cytokine in the pathogenesis of PD. Despite its well documented role in host defense against invading pathogens at oral barrier sites, IL-17A-mediated signaling can also lead to a detrimental inflammatory response, causing periodontal bone destruction. In this study, we developed a local sustained delivery system that restrains IL-17A hyperactivity in periodontal tissues by incorporating neutralizing anti-IL-17A Abs in poly(lactic-coglycolic) acid microparticles (MP). This formulation allowed for controlled release of anti-IL-17A in the periodontium of mice with ligature-induced PD. Local delivery of anti-IL-17A MP after murine PD induction inhibited alveolar bone loss and osteoclastic activity. The anti-IL-17A MP formulation also decreased expression of IL-6, an IL-17A target gene known to induce bone resorption in periodontal tissues. This study demonstrates proof of concept that local and sustained release of IL-17A Abs constitutes a promising therapeutic strategy for PD and may be applicable to other osteolytic bone diseases mediated by IL-17A-driven inflammation.

Hypercalcemia and Disseminated Osteolytic Lesions With Normal Blood Counts and Absence of Circulating Blasts: A Rare Presentation of Childhood B-Lymphoblastic Leukemia

Hypercalcemia and disseminated osteolytic bone lesions are a rare presentation of pediatric acute lymphoblastic leukemia (ALL). The authors report a 3-year-old boy who presented with hypercalcemia and diffuse osteolytic lesions involving axial and appendicular bones. He had normal complete blood count and the absence of blasts in peripheral smear; however, bone marrow aspirate and trephine were consistent with B-cell ALL. A review of the literature highlights the variable clinical outcome of this rare presentation depending on the presence of hypercalcemia and osteolytic lesions with or without chromosomal translocation t(17;19) and coagulation abnormalities. The patient had no coagulopathy and normal karyotype, and showed excellent response to initial treatment in terms of complete remission and negative minimal residual disease after standard-risk induction chemotherapy. Hypercalcemia with diffuse osteolytic lesions warrants bone marrow examination to rule out leukemia even in the absence of any abnormality in complete blood count. The case was reported for awareness of this rare presentation of ALL so that delays can be avoided for this potentially curable but life-threatening disease.

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.

No Role of Osteocytic Osteolysis in the Development and Recovery of the Bone Phenotype Induced by Severe Secondary Hyperparathyroidism in Vitamin D Receptor Deficient Mice

Osteocytic osteolysis/perilacunar remodeling is thought to contribute to the maintenance of mineral homeostasis. Here, we utilized a reversible, adult-onset model of secondary hyperparathyroidism to study femoral bone mineralization density distribution (BMDD) and osteocyte lacunae sections (OLS) based on quantitative backscattered electron imaging. Male mice with a non-functioning vitamin D receptor (VDRΔ/Δ) or wild-type mice were exposed to a rescue diet (RD) (baseline) and subsequently to a low calcium challenge diet (CD). Thereafter, VDRΔ/Δ mice received either the CD, a normal diet (ND), or the RD. At baseline, BMDD and OLS characteristics were similar in VDRΔ/Δ and wild-type mice. The CD induced large cortical pores, osteomalacia, and a reduced epiphyseal average degree of mineralization in the VDRΔ/Δ mice relative to the baseline (-9.5%, p < 0.05 after two months and -10.3%, p < 0.01 after five months of the CD). Switching VDRΔ/Δ mice on the CD back to the RD fully restored BMDD to baseline values. However, OLS remained unchanged in all groups of mice, independent of diet. We conclude that adult VDRΔ/Δ animals on an RD lack any skeletal abnormalities, suggesting that VDR signaling is dispensable for normal bone mineralization as long as mineral homeostasis is normal. Our findings also indicate that VDRΔ/Δ mice attempt to correct a calcium challenge by enhanced osteoclastic resorption rather than by osteocytic osteolysis.

Targeting anti-cancer agents to bone using bisphosphonates

The skeleton is affected by numerous primary and metastatic solid and hematopoietic malignant tumors, which can cause localized sites of osteolysis or osteosclerosis that can weaken bones and increase the risk of fractures in affected patients. Chemotherapeutic drugs can eliminate some tumors in bones or reduce their volume and skeletal-related events, but adverse effects on non-target organs can significantly limit the amount of drug that can be administered to patients. In these circumstances, it may be impossible to deliver therapeutic drug concentrations to tumor sites in bones. One attractive mechanism to approach this challenge is to conjugate drugs to bisphosphonates, which can target them to bone where they can be released at diseased sites. Multiple attempts have been made to do this since the 1990s with limited degrees of success. Here, we review the results of pre-clinical and clinical studies made to target FDA-approved drugs and other antineoplastic small molecules to bone to treat diseases affecting the skeleton, including osteoporosis, metastatic bone disease, multiple myeloma and osteosarcoma. Results to date are encouraging and indicate that drug efficacy can be increased and side effects reduced using these approaches. Despite these successes, challenges remain: no drugs have gone beyond small phase 2 clinical trials, and major pharmaceutical companies have shown little interest in the approach to repurpose any of their drugs or to embrace the technology. Nevertheless, interest shown by smaller biotechnology companies in the technology suggests that bone-targeting of drugs with bisphosphonates has a viable future.

Chitosan derived nitrogen-doped carbon dots suppress osteoclastic osteolysis via downregulating ROS

Osteoclasts are the main cells involved in normal bone remodeling and pathological bone destruction in vivo. Overactivation of osteoclasts can lead to osteolytic diseases, including breast cancer, bone tumors, arthritis, the aseptic loosening of orthopedic implants, and Paget's disease. Excessive reactive oxygen species are the main cause of osteoclast overactivation. We have synthesized chitosan derived nitrogen-doped carbon dots (N-CDs) with a high synthetic yield and the ability to scavenge reactive oxygen species (ROS). N-CDs effectively abrogated RANKL-induced elevation in ROS generation and therefore impaired the activation of NF-κB and MAPK pathways. Osteoclastogenesis and bone resorption was effectively attenuated in vitro. Furthermore, the in vivo administration of N-CDs in mice protected them against lipopolysaccharide (LPS)-induced calvarial bone destruction and breast cancer cell-induced tibial bone loss. Based on the good biocompatibility of N-CDs and the ability to efficiently remove ROS, a nanomaterial treatment scheme was provided for the first time for the clinical treatment of osteolytic diseases.

The role of Rho GTPases' substrates Rac and Cdc42 in osteoclastogenesis and relevant natural medicinal products study

Recently, Rho GTPases substrates include Rac (Rac1 and Rac2) and Cdc42 that have been reported to exert multiple cellular functions in osteoclasts, the most prominent of which includes regulating the dynamic actin cytoskeleton rearrangements. In addition, natural products and their molecular frameworks have a long tradition as valuable starting points for medicinal chemistry and drug discovery. Although currently, there are reports about the natural product, which could play a therapeutic role in bone loss diseases (osteoporosis and osteolysis) through the regulation of Rac1/2 and Cdc42 during osteoclasts cytoskeletal structuring. There have been several excellent studies for exploring the therapeutic potentials of various natural products for their role in inhibiting cancer cells migration and function via regulating the Rac1/2 and Cdc42. Herein in this review, we try to focus on recent advancement studies for extensively understanding the role of Rho GTPases substrates Rac1, Rac2 and Cdc42 in osteoclastogenesis, as well as therapeutic potentials of natural medicinal products for their properties on the regulation of Rac1, and/or Rac2 and Cdc42, which is in order to inspire drug discovery in regulating osteoclastogenesis.

Role of (Neo)adjuvant Denosumab for Giant Cell Tumor of Bone

OPINION STATEMENT

Denosumab is a RANK ligand inhibitor approved for the treatment of giant cell tumor of bone. While the role of denosumab in the setting of advanced and unresectable disease is well established, its role in surgically resectable disease is currently under discussion. Several prospective and retrospective series on neoadjuvant therapy in potentially resectable tumor with high morbidity surgery reported a relapse rate of 10-20% after resection and 30-40% after curettage. At the same time, less morbid surgery has obvious clinical advantages for the patient, and several studies have shown the efficacy of denosumab in downgrading of the surgical procedure. Currently, the role of neoadjuvant denosumab in operable GCTB is limited to selected cases in which a diffuse reactive bone formation and peripheral ossification can make an easier surgical procedure, for example, in tumors with a large soft tissue component. A planned resection may become less morbid when preoperative denosumab is administered. Whenever a segmental resection is thought to be indicated at diagnosis, denosumab may be considered in the neoadjuvant setting. A preoperative course of 6 months is considered safe and effective. Two case scenarios are presented and critically discussed. Because of the high recurrence rates after denosumab treatment followed by curettage, we discourage the use of denosumab when curettage is considered feasible. In this setting, a short course of preoperative denosumab (2-6 months) may be considered for highly selected cases, for example in pathological fractures. The role of adjuvant denosumab needs further investigation. Long-term disease control has been reported in case of non-surgical lesions, even after treatment interruption, but there is no consensus on ideal treatment duration and dosage for these scenarios. In all cases, multidisciplinary discussion with oncology, pathologist, radiologist, and surgeons is mandatory. Patient's comorbidities, dental conditions, and preferences, including family planning, should always be taken into account.

Bone-Specific Metabolism of Dietary Polyphenols in Resorptive Bone Diseases

SCOPE

Curcumin prevents bone loss in resorptive bone diseases and inhibits osteoclast formation, a key process driving bone loss. Curcumin circulates as an inactive glucuronide that can be deconjugated in situ by bone's high β-glucuronidase (GUSB) content, forming the active aglycone. Because curcumin is a common remedy for musculoskeletal disease, effects of microenvironmental changes consequent to skeletal development or disease on bone curcumin metabolism are explored.

METHODS AND RESULTS

Across sexual/skeletal development or between sexes in C57BL/6 mice ingesting curcumin (500 mg kg-1 ), bone curcumin metabolism and GUSB enzyme activity are unchanged, except for >twofold higher (p < 0.05) bone curcumin-glucuronide substrate levels in immature (4-6-week-old) mice. In ovariectomized (OVX) or bone metastasis-bearing female mice, bone substrate levels are also >twofold higher. Aglycone curcumin levels tend to increase proportional to substrate such that the majority of glucuronide distributing to bone is deconjugated, including OVX mice where GUSB decreases by 24% (p < 0.01). GUSB also catalyzes deconjugation of resveratrol and quercetin glucuronides by bone, and a requirement for the aglycones for anti-osteoclastogenic bioactivity, analogous to curcumin, is confirmed.

CONCLUSION

Dietary polyphenols circulating as glucuronides may require in situ deconjugation for bone-protective effects, a process influenced by bone microenvironmental changes.

Radiation therapy combined with bone-modifying agents ameliorates local control of osteolytic bone metastases in breast cancer

Bone-modifying agents (BMAs) are frequently used for the treatment of bone metastases. Both BMA and radiation therapy (RT) are effective; however, there are few studies that have evaluated the efficacy of the combination treatment. We evaluated the effectiveness of RT + BMA in breast cancer-induced osteolytic bone metastasis as compared to BMA alone. A total of 43 lesions in 25 patients were evaluated. The median follow-up period was 18 (range, 2-90) months. None of the lesions was treated with chemotherapy or molecular targeted drugs during the follow-up period for evaluating the local response. Patients with complete or partial response were considered as responders, while those with stable or progressive disease were considered as non-responders. The rate of response with RT + BMA was significantly higher than that with BMA alone (P = 0.001). The cumulative incidence rate of response at 6 months was 54.4% in the RT + BMA group and 27.5% in the BMA alone group. The median time to response was 4 (range, 2-11) months in the RT + BMA group and 6 (range, 4-16) months in the BMA alone group. The overall survival rate in the responder group (83.1% at 1 year) was significantly higher than that in the non-responder group (37.5% at 1 year) (P = 0.029). In conclusion, RT combined with BMA was found to be more effective than BMA alone for the treatment of osteolytic bone metastasis, which thereby improves the prognosis.

Metal-Organic Framework Nanoparticles for Ameliorating Breast Cancer-Associated Osteolysis

Breast cancer metastases to bone poses a significant challenge for the administration of treatment strategies. The bone microenvironment, metastatic tumor cells, osteoclasts, and tumor-associated macrophages (TAMs) all play crucial and synergistic roles in creating a favorable environment for the proliferation, progression, and survival of the metastatic tumor, which in turn induces osteoclast-mediated bone destruction. In this study, we functionalized immunostimulatory cytosine-phosphate-guanosine (CpG)-loaded metal-organic framework (MOF) nanoparticles with bone targeting capabilities by surface modification with FDA approved antiresorptive bisphosphonate, zoledronic acid (ZOL). The functionalized bone targeting immunostimulatory MOF (BT-isMOF) nanoparticles demonstrates strong binding to calcium phosphate in vitro and exhibits specific targeting and accumulation in bone tissues in vivo. In vitro cellular and biochemical analyses demonstrated that the BT-isMOF nanoparticles could potently inhibit osteoclast formation and concomitantly induce macrophages polarization toward the M1 pro-inflammatory phenotype. Finally, using the intratibial murine model of breast cancer bone metastasis, we showed that the administration of BT-isMOF nanoparticles significantly suppressed osteoclast-mediated bone destruction and enhanced polarization of tumor-resident macrophages to M1 phenotype. Together, our data provides promising evidence for the potential therapeutic application of the BT-isMOF nanoparticles in the treatment of breast cancer bone metastases.

In vitro and in vivo Biological Responses to Graphene and Graphene Oxide: A Murine Calvarial Animal Study

BACKGROUND

Graphene and its derivatives have recently gained popularity in the biomedical field. Previous studies have confirmed that both the mechanical strength and wear resistance of graphene-containing polyethylene have been greatly improved. Therefore, it is being considered as an alternative for artificial joint replacement liners. Based on the literature, the wear debris generated from the traditional polymers used for orthopedic liners could lead to particle-induced osteolysis and, consequently, failure of joint replacement. However, the biological response of this novel graphene-based polymer is still unclear. Therefore, the current study aimed to investigate the in vitro and in vivo biological effects of graphene and graphene oxide (GO) particles on bone.

MATERIALS AND METHODS

The biological responses of graphene and GO particles were tested via in vitro and murine calvarial in vivo models. In the in vitro model, murine macrophage cells were mixed with particles and hydrogel and printed into two differently designed scaffolds; the induced proinflammatory cytokines were then tested. In the murine in vivo model, the particle size distribution was measured via SEM, and these particles were then administrated in the calvarial area, referring to our established model. A micro-CT and histological analysis were performed to examine the biological effects of the particles on bone health. The data were analyzed via the one-way analysis of variance to determine the differences between the groups.

RESULTS

Both graphene and GO induced significantly higher TNF-α and IL-6 secretion compared with the control in the three-dimensional in vitro model. In the murine calvarial in vivo test, the graphene and GO particles increased the bone mass compared with the sham groups in the micro-CT analysis. Bone formation was also observed in the histological analysis.

CONCLUSION

In these in vivo and in vitro studies, the graphene and GO wear debris did not seem to induce harmful biological response effect to bone. Bone formation around the skull was observed in the calvarial model instead. Graphene-containing biomaterials could be a suitable new material for application in orthopedic prostheses due to their benefit of eliminating the risk of particle-induce osteolysis.

Bacillus cereus isolated from a positive bone tissue culture in a patient with osteolysis and high-titer anti-interferon-γ autoantibodies: A case report

RATIONALE

Bacillus cereus (B cereus) is an aerobic or facultative anaerobic gram-positive, spore-forming bacterium. It can cause fatal disease and generally manifests as 3 distinct syndromes: food intoxication, localized infection, and systemic infection. It is a rare infection that can occur in immunocompetent persons with osteolytic and high-titer anti-IFN-γ autoantibodies.

PATIENT CONCERNS

We reported a case of an HIV-negative 24-year old man with an interrupted fever and a 20-day history of progressive ache in the right thigh and high-titer anti-IFN-γ autoantibodies. Magnetic resonance imaging, X-radiography, high-resolution computed tomography, and 3-dimensional reconstruction of the bone showed multiple lucent defects with moth-eaten destruction of the bone and cortical substance of bone in the right femur. Emission CT showed significantly increased uptake in the femur.

DIAGNOSIS AND INTERVENTIONS

The patient was originally misdiagnosed with osteosarcoma; acute osteomyelitis was also considered. He received intravenous piperacillin, sulbactam, and levofloxacin during hospitalization; however, he did not respond to the 3-week antibiotic course and his condition worsened. After cultures from incisional biopsy specimens were obtained from the femoral cavity, B cereus-induced osteomyelitis was diagnosed. He received intravenous injections of moxifloxacin 400 mg qd for 4 weeks and oral moxifloxacin 400 mg qd for 8 weeks.

OUTCOMES

The patient's symptoms and signs improved. His X-radiography, HRCT, MRI, and 3-dimensional reconstruction of the bone showed absolute absorption in the right femur. However, the anti-IFN-γ autoantibody titer was still high. No recurrence was observed after 24 months of follow-up. He is still undergoing follow-up at this time.

LESSONS

This is the first case involving a patient with B cereus infection showing a high titer of anti-IFN-γ autoantibodies. B cereus infection can involve the bone, leading to osteolysis in HIV-negative individuals. Although this patient was HIV-negative and had no other comorbidities, the presence of high titer anti-IFN-γ autoantibodies may be the primary reason for B cereus infection. Clinicians should pay more attention to the identification of osteolytic destruction caused by tumor and infection.

Diosmetin inhibits osteoclast formation and differentiation and prevents LPS-induced osteolysis in mice

Osteolytic bone diseases are closely linked to the over-activation of osteoclasts and enhancement of bone resorption. It has become a major health issue in orthopedic practice worldwide. Inhibition of osteoclasts is proposed to be the main treatment for osteolytic disorders. Diosmetin (DIO) is a natural flavonoid with properties of antioxidant, anti-infection, and antishock. The effect of DIO on osteoclast differentiation is poorly understood. In this study project, we found that DIO could inhibit osteoclastic formation induced by receptor activator of nuclear factor kappa-B ligand (RANKL) in a dose-dependent manner. The expression of the osteoclast differentiation marker genes, cathepsin K, nuclear factor of activated T-cells 1 (NFATc1), Acp5, Ctr, Atp6v0d2, and Mmp9 were also decreased by the treatment of DIO. In addition, DIO attenuated the formation of actin ring and the ability of bone resorption. Further, the western blotting showed that DIO inhibits the phosphorylation of the mitogen-activated protein kinases signaling pathway induced by RANKL, accompanied by the downregulation of NFATc1 and c-Fos expression. We also found that DIO could reduce the accumulation of reactive oxygen species (ROS) induced by RANKL. In vivo, the study revealed that DIO can significantly reduce LPS-induced osteolysis in mice. Collectively, our study shows that DIO can inhibit osteoclast formation and activation, and could serve as a potential therapeutic drug for osteolytic bone diseases.

Daphnetin attenuates LPS-induced osteolysis and RANKL mediated osteoclastogenesis through suppression of ERK and NFATc1 pathways

Aseptic prosthetic loosening and periprosthetic infection resulting in inflammatory osteolysis is a leading complication of total joint arthroplasty (TJA). Excessive bone destruction around the bone and prosthesis interface plays a key role in the loosening prostheses leading to revision surgery. The bacterial endotoxins or implant-derived wear particles-induced inflammatory response is the major cause of the elevated osteoclast formation and activity. Thus, agents or compounds that can attenuate the inflammatory response and/or inhibit the elevated osteoclastogenesis and excessive bone resorption would provide a promising therapeutic avenue to prevent aseptic prosthetic loosening in TJA. Daphnetin (DAP), a natural coumarin derivative, is clinically used in Traditional Chinese Medicine for the treatment of rheumatoid arthritis due to its anti-inflammatory properties. In this study, we report for the first time that DAP could protect against lipopolysaccharide-induced inflammatory bone destruction in a murine calvarial osteolysis model in vivo. This protective effect of DAP can in part be attributed to its direct inhibitory effect on RANKL-induced osteoclast differentiation, fusion, and bone resorption in vitro. Biochemical analysis found that DAP inhibited the activation of the ERK and NFATc1 signaling cascades. Collectively, our findings suggest that DAP as a natural compound has potential for the treatment of inflammatory osteolysis.

Anti-inflammatory drug-eluting implant model system to prevent wear particle-induced periprosthetic osteolysis

BACKGROUND

Aseptic loosening, as a consequence of an extended inflammatory reaction induced by wear particles, has been classified as one of the most common complications of total joint replacement (TJR). Despite its high incidence, no therapeutical approach has yet been found to prevent aseptic loosening, leaving revision as only effective treatment. The local delivery of anti-inflammatory drugs to modulate wear-induced inflammation has been regarded as a potential therapeutical approach to prevent aseptic-loosening.

METHODS

In this context, we developed and characterized anti-inflammatory drug-eluting TiO2 surfaces, using nanoparticles as a model for larger surfaces. The eluting surfaces were obtained by conjugating dexamethasone to carboxyl-functionalized TiO2 particles, obtained by using either silane agents with amino or mercapto moieties.

RESULTS

Zeta potential measurements, thermogravimetric analysis (TGA) and drug release results suggest that dexamethasone was successfully loaded onto the TiO2 particles. Release was pH dependent and greater amounts of drug were observed from amino route functionalized surfaces. The model-system was then tested for its cytotoxic and anti-inflammatory properties in LPS-stimulated macrophages. Dexamethasone released from amino route functionalized surfaces TiO2 particles was able to decrease LPS-induced nitric oxide (NO) and TNF-a production similarly to pure DEX at the same concentration; DEX released from mercapto route functionalized surfaces was at a too low concentration to be effective.

CONCLUSION

Dexamethasone released from amino functionalized titanium can offer the possibility of preventing asepting loosening of joint replacement devices.

A Carboxyl-Terminated Dendrimer Enables Osteolytic Lesion Targeting and Photothermal Ablation of Malignant Bone Tumors

Malignant bone tumor accompanied by tumor-associated osteolysis remains a challenging task in clinical practice. Nanomedicines engineered with bone-targeting ligands, such as alendronate and pamidronate, are developed for targeted delivery of therapeutic agents to bone tumors. However, these targeting strategies usually show relatively poor selectivity toward the healthy skeletons and the osteolytic lesions because of the high binding affinity of bisphosphonates with all the bone tissues. Here, we reported a carboxyl-terminated dendrimer as the candidate to preferentially deliver therapeutic nanoparticles to the osteolytic lesions in a malignant bone tumor model. The high density of carboxyl groups on dendrimer surface endow the polymer with natural bone-binding capability. The dendrimer encapsulated with platinum nanoparticle predominantly accumulates at the osteolytic lesions around bone tumors rather than at healthy bone tissues in vivo. The therapeutic experiments reveal that the dendrimer-mediated photothermal therapy efficiently suppresses bone tumors and osteolysis, and the anionic polymer exhibits minimal cytotoxicity and hematologic toxicity. The results suggest that the carboxyl-terminated dendrimer is a promising candidate for selective delivery of therapeutics to the osteolytic lesions and photothermal treatment of malignant bone tumors.

The potent anti-inflammatory effect of Guilu Erxian Glue extracts remedy joint pain and ameliorate the progression of osteoarthritis in mice

BACKGROUND

Osteoarthritis (OA) is a slow progressing, degenerative disorder of the synovial joints. Guilu Erxian Glue (GEG) is a multi-component Chinese herbal remedy with long-lasting favorable effects on several conditions, including articular pain and muscle strength in elderly men with knee osteoarthritis. The present study aimed to identify the effects of Guilu Erxian Paste (GE-P) and Liquid (GE-L) extracted from Guilu Erxian Glue in anterior cruciate ligament transection (ACLT)-induced osteoarthritis mice, and to compare the effectiveness of different preparations on knee cartilage degeneration during the progression of osteoarthritis.

METHODS

Male C57BL/6J mice underwent anterior cruciate ligament transection to induce mechanically destabilized osteoarthritis in the right knee. 4 weeks later, the mice were orally treated with PBS, celecoxib (10 mg/kg/day), Guilu Erxian Paste (100 or 300 mg/kg/day), and Guilu Erxian Liquid (100 or 300 mg/kg/day) for 28 consecutive days. Von Frey and open-field tests (OFT) were used to evaluate pain behaviors (mechanical hypersensitivity and locomotor performance). Narrowing of the joint space and osteophyte formation were examined radiographically. Inflammatory cytokine (IL-1β, IL-6, and TNF-α) levels in the articular cartilage were determined by quantitative real-time PCR. Histopathological examinations were conducted to evaluate the severity and extent of the cartilage lesions.

RESULTS

Guilu Erxian Paste and Guilu Erxian Liquid (300 mg/kg/day) were significantly more effective (p < 0.01) than celecoxib (10 mg/kg/day) in decreasing secondary allodynia when compared to the saline-treated group (#p < 0.05). Open-field tests revealed no significant motor dysfunction between the Guilu Erxian Paste- and Guilu Erxian Liquid-treated mice compared to the saline-treated mice. Radiographic findings also confirmed that the administration of Guilu Erxian Paste and Guilu Erxian Liquid (100 and 300 mg/kg/day) significantly and dose-dependently reduced osteolytic lesions and bone spur formation in the anterior cruciate ligament transection-induced osteoarthritis mice when compared to the saline-treated group. Notably, Guilu Erxian Liquid (100 mg/kg/day) treatment significantly reduced the mRNA levels of IL-1β, IL-6, and TNF-α as well as relative the protein expression of IL-1β and TNF-α to the effect of celecoxib. Guilu Erxian Paste and Guilu Erxian Liquid (300 mg/kg/day) markedly attenuated cartilage destruction, surface unevenness, proteoglycan loss, chondrocyte degeneration, and cartilage erosion in the superficial layers (##p < 0.01 and ###p < 0.001 respectively).

CONCLUSIONS

As expected, our findings suggest that the anti-inflammatory effects of Guilu Erxian Liquid (GE-L), following marked decrease on both IL-1β and TNF-α during the early course of post-traumatic osteoarthrosis (OA), may be of potential value in the treatment of osteoarthritis.

Clarithromycin as the empiric antibiotic therapy for medication-related osteonecrosis of the jaw in multiple myeloma patients

About half of individuals diagnosed with medication-related osteonecrosis of the jaw (MRONJ) are multiple myeloma (MM) patients, and most are treated using antibiotics for long-term courses. The penicillin group is recommended as the empiric drug of choice, and quinolones, metronidazole, clindamycin, doxycycline, and erythromycin as alternatives. This paper suggests the macrolide clarithromycin as the empiric antibiotic therapy of MRONJ in MM patients because of its better pharmacologic properties in comparison to erythromycin, and the beneficial effect of this agent in MM. This empiric antibiotic regimen should be later adjusted according to the response and findings of the microbial cultures.

Amentoflavone Inhibits Osteoclastogenesis and Wear Debris-Induced Osteolysis via Suppressing NF-κB and MAPKs Signaling Pathways

Wear debris-induced osteolysis is one of the major reasons for subsequent aseptic loosening after cementless hip arthroplasty. Increasing evidence suggests that receptor activator of nuclear factor kappa-B (NF-κB) ligand-mediated osteoclastogenesis and osteolysis are responsible for wear debris-induced aseptic loosening. In the present study, we explored the effect of amentoflavone (AMF) on inhibiting osteoclast generation and wear debris-induced osteolysis in vitro and in vivo. Twenty-four male C57BL/J6 mice were randomly divided into four groups: a sham group and groups with titanium wear debris treatment followed by intraperitoneal injection of various concentrations of AMF (0, 20, and 40 mg/kg/day). The micro computed tomography scanning and histological analysis were performed. Bone marrow-derived macrophages were cultured to investigate the effect of AMF on osteoclast generation and function. The results showed that AMF suppressed osteoclastogenesis, F-actin ring formation, and bone absorption without cytotoxicity. AMF prevented titanium wear debris-induced osteolysis in mice. AMF suppressed the relative proteins of NF-κB and mitogen-activated protein kinase (MAPKs) signaling pathways. Thus, the present study suggests that AMF derived from plants could inhibit osteoclastogenesis and titanium wear debris-induced osteolysis via suppressing NF-κB and MAPKs signaling pathways.

Altered microRNA expression profile in the peripheral lymphoid compartment of multiple myeloma patients with bisphosphonate-induced osteonecrosis of the jaw

Bisphosphonates are formidable inhibitors of osteoclast-mediated bone resorption employed for therapy of multiple myeloma (MM) subjects with osteolytic lesions. Osteonecrosis of the jaw (ONJ) is an uncommon drug-induced adverse event of these agents. MicroRNAs (miRNAs) are a group of small, noncoding RNAs nucleotides, which are essential post-transcriptional controllers of gene expression. They have a central role in the normal bone development. The goal of our study was to investigate 18 miRNAs, whose targets were previously validated and described in MM subjects without ONJ, in peripheral lymphocytes of MM subjects with bisphosphonate-induced ONJ. Utilizing reverse transcription quantitative polymerase chain reaction, we evaluated miRNAs in five healthy subjects and in five MM patients with ONJ. Our experimental data revealed that a diverse miRNA signature for ONJ subjects emerged with respect to control subjects. Using the filter for in silico analysis, among the 18 miRNAs, we recognized 14 dysregulated miRNAs. All these miRNAs were significantly over-expressed in patients vs controls (MIR-16-1, MIR-21, MIR-23A, MIR-28, MIR-101-1, MIR-124-1, MIR-129, MIR-139, MIR-145, MIR-149, MIR-202, MIR-221, MIR-424, MIR-520). Among them, six were strongly upregulated (fourfold upregulated and more). These miRNAs target numerous pathways and genes implicated in calcium ion binding, bone resorption, mineralization of bone matrix, and differentiation and maintenance of bone tissue. A modified microRNA expression profile after zoledronate therapy could participate to the onset of ONJ. Targeting these miRNAs could provide a new opportunity for the prevention or treatment of ONJ.

Tracking the Progression of Osteolytic and Osteosclerotic Lesions in Mice Using Serial In Vivo μCT: Applications to the Assessment of Bisphosphonate Treatment Efficacy

The metastasis of tumor cells to bone can lead to osteolytic and osteosclerotic lesions, which cause severe, highly-localized bone destruction and abnormal bone apposition, respectively. Accurate quantification of lesion progression is critical to understand underlying mechanisms and assess treatment efficacy; however, standard structural parameters may be insensitive to local changes. We developed methods to quantify osteolytic and osteosclerotic lesions using micro-computed tomography (μCT) within in vivo mouse datasets. Two Balb/c nude datasets were used: (i) bone-homing MDA-MB-231 (osteolytic) cells injected into the left ventricle, treatment with alendronate or vehicle, and weekly μCT (proximal tibia) for 4 weeks, and (ii) MCF7 (osteosclerotic) cells injected into the right tibia and weekly μCT over 12 weeks. After registering images to baseline, osteolytic lesion volume was determined by summing all baseline bone voxels at distances greater than a threshold (150 μm) from the nearest follow-up. Osteosclerotic lesions were determined by measuring the distance from each follow-up surface voxel to the nearest baseline surface and calculating the standard deviation of distance values (SDDT) of the surrounding voxels. Bone mineral density (BMD), bone volume density (BV/TV), and separation (Sp) were determined for comparison. Osteolytic lesions were observed 1 week after tumor cell injection; however, no corresponding BV/TV losses or Sp increases were observed, indicating that standard parameters were unable to detect early metastatic changes. Lesion volume was smaller in the alendronate versus control group (15.0%, p = 0.004 and 18.6%, p = 0.002 of control lesion volume at weeks 3 and 4, respectively). In the osteosclerotic dataset, increased SDDT was observed following injection, providing a potential new measure of osteosclerotic bone apposition. These data show that quantification of local structural change with serial μCT may overcome the limitations of standard mineral and microstructural parameters, and successfully separates metastatic and normal bone turnover. © 2017 American Society for Bone and Mineral Research.

Hallmarks of Bone Metastasis

Breast cancer bone metastasis develops as the result of a series of complex interactions between tumor cells, bone marrow cells, and resident bone cells. The net effect of these interactions are the disruption of normal bone homeostasis, often with significantly increased osteoclast and osteoblast activity, which has provided a rational target for controlling tumor progression, with little or no emphasis on tumor eradication. Indeed, the clinical course of metastatic breast cancer is relatively long, with patients likely to experience sequential skeletal-related events (SREs), often over lengthy periods of time, even up to decades. These SREs include bone pain, fractures, and spinal cord compression, all of which may profoundly impair a patient's quality-of-life. Our understanding of the contributions of the host bone and bone marrow cells to the control of tumor progression has grown over the years, yet the focus of virtually all available treatments remains on the control of resident bone cells, primarily osteoclasts. In this perspective, our focus is to move away from the current emphasis on the control of bone cells and focus our attention on the hallmarks of bone metastatic tumor cells and how these differ from primary tumor cells and normal host cells. In our opinion, there remains a largely unmet medical need to develop and utilize therapies that impede metastatic tumor cells while sparing normal host bone and bone marrow cells. This perspective examines the impact of metastatic tumor cells on the bone microenvironment and proposes potential new directions for uncovering the important mechanisms driving metastatic progression in bone based on the hallmarks of bone metastasis.

A single intraperitoneal injection of bovine fetuin-A attenuates bone resorption in a murine calvarial model of particle-induced osteolysis

Particle-induced osteolysis, which by definition is an aseptic inflammatory reaction to implant-derived wear debris eventually leading to local bone destruction, remains the major reason for long-term failure of orthopedic endoprostheses. Fetuin-A, a 66kDa glycoprotein with diverse functions, is found to be enriched in bone. Besides being an important inhibitor of ectopic calcification, it has been described to influence the production of mediators of inflammation. Furthermore, a regulatory role in bone metabolism has been assigned. In the present study, the influence of a single dose of bovine fetuin-A, intraperitoneally injected in mice subjected to particle-induced osteolysis of the calvaria, was analyzed. Twenty-eight male C57BL/6 mice, twelve weeks of age, were randomly divided into four groups. Groups 2 and 4 were subjected to ultra-high molecular weight polyethylene (UHMWPE) particles placed on their calvariae while groups 1 and 3 were sham-operated. Furthermore, groups 3 and 4 received a single intraperitoneal injection of 20mg bovine fetuin-A while groups 1 and 2 were treated with physiologic saline. After 14days calvarial bone was qualitatively and quantitatively assessed using microcomputed tomography (μCT) and histomorphometrical approaches. Application of fetuin-A led to a reduction of particle-induced osteolysis in terms of visible osteolytic lesions and eroded bone surface. The reduction of bone thickness and bone volume, as elicited by UHMWPE, was alleviated by fetuin-A. In conclusion, fetuin-A was found to exert an anti-resorptive effect on particle-induced osteolysis in-vivo. Thus, fetuin-A could play a potentially osteoprotective role in the treatment of bone metabolic disorders.

Myeloma and Bone Disease

PURPOSE OF REVIEW

Bone disease is a defining characteristic of multiple myeloma (MM) and the major cause of morbidity. It manifests as lytic lesions or osteopenia and is often associated with severe pain, pathological fracture, spinal cord compression, vertebral collapse, and hypercalcemia. Here, we have reviewed recent data on understanding its biology and treatment.

RECENT FINDINGS

The imbalance between bone regeneration and bone resorption underlies the pathogenesis of osteolytic bone disease. Increased osteoclast proliferation and activity accompanied by inhibition of bone-forming osteoblasts leads to progressive bone loss and lytic lesions. Although tremendous progress has been made, MM remains an incurable disease. Novel agents targeting bone disease are under investigation with the goal of not only preventing bone loss and improving bone quality but also harnessing MM tumor growth. Current data illustrate that the interactions between MM cells and the tumor-bone microenvironment contribute to the bone disease and continued MM progression. A better understanding of this microenvironment is critical for novel therapeutic treatments of both MM and associated bone disease.

Study on critical-sized ultra-high molecular weight polyethylene wear particles loaded with alendronate sodium: in vitro release and cell response

The aim of this study was to investigate the in vitro release and the effect of RAW 264.7 macrophages of critical-sized wear particles of ultra-high molecular weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN), one of the most effective drugs to treat osteoporosis in clinic. The critical-sized UHMWPE-ALN 0.5 wt.% wear particles were prepared by vacuum gradient filtration combined with Pluronic F-68. In vitro release of ALN from critical-sized UHMWPE-ALN wear particles was investigated in phosphate buffered saline (PBS) at 37 °C with a shaker. Cell morphology, proliferation, lactate dehydrogenase (LDH) leakage and secretions of cytokines were evaluated after co-cultured with critical-sized UHMWPE-ALN wear particles in vitro. Results showed that ALN released from critical-sized UHMWPE-ALN wear particles included burst release and slow release in vitro. Macrophages would be chemotaxis and aggregated around the critical-sized UHMWPE-ALN or UHMWPE wear particle, which was phagocytosed with time. The proliferation of macrophages co-cultured with critical-sized UHMWPE-ALN wear particles was significantly decreased compared with that of critical-sized UHMWPE group. Meanwhile, the critical-sized UHMWPE-ALN wear particles significantly induced the LDH leakage of macrophages, which indicated the cell death. The death of macrophages induced by ALN was one of pathways to inhibit their proliferation. The secretions of cytokines (interleukin-6 and tumor necrosis factor-alpha) in critical-sized UHMWPE-ALN group were significantly lower than those in critical-sized UHMWPE group due to the released ALN. The present results suggested that UHMWPE-ALN had the potential application in clinic to treat osteolysis induced by wear particles.