Receptor Activator Of Nuclear factor-κB Ligand Research Articles

A tetravalent peptide that binds to the RANK-binding region of TRAF6 via a multivalent interaction efficiently inhibits osteoclast differentiation

Inhibition of osteoclast differentiation is a promising approach for the treatment of osteoporosis and rheumatoid arthritis. Receptor activator of nuclear factor kappa B (NF-κB) (RANK), which is an essential molecule for osteoclast differentiation, interacts with tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) to transduce downstream signals. Both RANK and TRAF6 have homo-trimeric structures, forming a multivalent interaction between the Pro-X-Glu-X-X-(aromatic/acidic) motif of RANK and the C-terminal domain of TRAF6 (TRAF-C), that markedly increases the binding affinity. Here, we designed a tetravalent peptide, RANK-tet, containing the TRAF-C-binding motif of RANK and found that RANK-tet binds to TRAF-C with high affinity. In contrast, a monomeric form of RANK-tet (RANK-mono) with the same TRAF-C-binding motif did not bind to TRAF-C, clearly indicating the multivalent interaction is strictly required for the high-affinity binding to TRAF-C. RANK-tet did not bind to a series of TRAF-C-mutants with an amino acid substitution in the RANK-binding region, indicating that RANK-tet specifically targets the RANK-binding region of TRAF-C. A cell-permeable form of RANK-tet that has poly-Arg residues at each C-terminal of the TRAF-C-binding motif efficiently inhibited the RANK ligand (RANKL)-induced differentiation of bone marrow cells to osteoclasts. Thus, this compound can be an effective anti-osteoclastogenic agent.

ПЛОТНОСТЬ КОСТНОЙ ТКАНИ И ЕЕ РЕГУЛЯЦИЯ В ЗАВИСИМОСТИ ОТ СОСТОЯНИЯ ОБМЕНА МАГНИЯ У ЖЕНЩИН ПОСТМЕНОПАУЗАЛЬНОГО ВОЗРАСТА С АРТЕРИАЛЬНОЙ ГИПЕРТЕНЗИЕЙ И ХРОНИЧЕСКОЙ СЕРДЕЧНОЙ НЕДОСТАТОЧНОСТЬЮ

The aim of study was to identify markers of bone turnover such as osteoprotegerin (OPG), receptor activator for nuclear factor kappa-B ligand (RANKL), 25-hydroxyvitamin D (25(OH)D), and bone density (BMD) in postmenopausal women with arterial hypertension (AH) and heart failure with preserved ejection fraction (HFpEF), depending on magnesium (Mg) status. Material and methods. 140 postmenopausal women aged 52 to 76 years with AH and HFpEF were examined. Based on the Mg-tolerance test, patients were divided into 2 groups: with Mg deficiency (n=72) and without one (n=68). BMD in the neck and proximal femoral area, as well as L1-L4 vertebrae, was measured in by dual-energy X-ray absorptiometry. OPG, soluble RANKL (sRANKL) and 25(OH)D level was also determined by enzyme immunoassay. Results. In Mg deficiency group were noted lower BMD indices in L1-L4 vertebrae area (0,990±0,159 g/cm2 vs 1,046±0,193 g/cm2; p=0,041) and higher osteopenia incidence (RR=1,60; 95% CI: 1,08–2,38; p=0,019). Also, Mg deficient women had higher level of OPG (85,2 [69,1; 103,1] pg/ml vs 79,9 [63,4; 92,7] pg/ml, p=0,035) and sRANKL (3,98 [2,70; 5,45] pg/ml vs 2,85 [1,95; 3,82] pg/ml, p<0,0001) expression, but lower OPG/sRANKL ratio (22.59 [15.34; 33.71] vs 26.01 [19.42; 41.19], p=0.028) in opposite to control group parameters. At the same time, patients with Mg deficiency had higher 25(OH)D impaired status incidence (97% vs 87%; p=0,028). Conclusion. Lower BMD and OPG/sRANKL ratio, but higher OPG and sRANKL expression and higher frequency of 25(OH)D impaired status were revealed in postmenopausal women with AH, HFpEF and Mg deficiency compared to the control group.

Endothelial SIRT-1 has a critical role in the maintenance of capillarization in brown adipose tissue

Brown adipose tissue (BAT) has critical roles in thermogenesis and systemic metabolism. Capillary rarefaction was reported to develop in BAT with dietary obesity, and previous studies showed that suppression of vascular endothelial growth factor A (VEGF-A) reduced capillary density in BAT, promoting the functional decline of this organ. Capillarization is regulated through the balance between angiogenesis and vasculogenesis on the one hand and apoptosis of endothelial cells (ECs) on the other; however, the role of EC apoptosis in BAT remained to be explored. In studies testing the role of boysenberry polyphenols (BoyP) in BAT, we found that BoyP decreased EC apoptosis, enhanced capillarization in BAT, and ameliorated dietary BAT dysfunction, which was associated with the upregulation of nicotinamide adenine dinucleotide-dependent protein deacetylase sirtuin 1 (SIRT-1) in ECs. Our studies suggest that EC SIRT-1 would be one of the potential targets of BoyP that contributes to BAT capillarization and function.

Serum fetuin-A and RANKL levels in patients with early stage breast cancer.

Breast cancer (BC) is the primary cause of mortality due to cancer in females around the world. Fetuin-A is known to increase metastases over signals and peroxisomes related with growing. Receptor activator of nuclear factor-kB ligand (RANKL) takes part in cell adhesion, and RANKL inhibition is used in the management of cancer. We aimed to examine the relationship between serum fetuin-A, RANKL levels, other laboratory parameters and clinical findings in women diagnosed with early stage BC, in our population. Women having early stage BC (n=117) met our study inclusion criteria as they had no any anti-cancer therapy before. Thirty-seven healthy women controls were also confirmed with breast examination and ultrasonography and/or mammography according to their ages. Serum samples were stored at -80°C and analysed via ELISA. Median age of the patients was 53 (range: 57-86) while it was 47 (range: 23-74) in the healthy group. Patients had lower high-density lipoprotein levels (p=0.002) and higher neutrophil counts (p=0.014). Fetuin-A and RANKL levels did not differ between the groups (p=0.116 and p=0.439, respectively) but RANKL leves were found to be lower in the favorable histological subtypes (p=0.04). In this study, we found no correlation between serum fetuin-A levels and clinical findings in patients diagnosed with early stage BC. However, RANKL levels are found to be lower in subgroups with favorable histopathologic subtypes such as tubular, papillary and mucinous BC and there was statistically significant difference.

Bone health program: A community cancer center's experience.

360 Background: Aromatase inhibitors (AI) are an essential treatment for postmenopausal women with hormone receptor-positive breast cancer in the adjuvant setting. Estrogen deficiency caused by AIs has adverse effects on bone health. Studies reveal that 5 years of treatment with anastrozole led to 6.1% of bone loss at the lumbar spine and 7.2% at the hip. The aim of the project is to identify the current degree of attention to bone health and skeletal-related complications in women with early-stage breast cancer stages I-III that are on AIs at a community cancer center at Einstein Medical Center Montgomery. Methods: This is a retrospective chart review of 63 patients ages 50-85 diagnosed with early-stage I-III breast cancer on an AI in the adjuvant setting. Patients who started on an AI between January 2013 through December 2017 were included. Data on Dual-energy X-ray absorptiometry scans (DEXA) and treatment at baseline, 2-years, and 4-years were analyzed. We followed to see if they had a DEXA scan every 2 years after the baseline DEXA scan for the following 4 years and analyzed information on their bone health. Results: Patients included were on an AI throughout the 4 years. The median age was 60.2 years. 46/63 (73%) had a baseline DEXA scan. Out of these, 12/63 had a normal bone density. 28/63 had osteopenia, of which 16/28 were treated. 6/63 had osteoporosis and only 2/6 were treated. After 2 years, 39/63 (61%) had a 2-year DEXA scan. Of these, 8 had a normal bone density. 26/63 had osteopenia of which 21/26 were treated. 5/63 had osteoporosis and all 5 were treated for this. At 4 years, 40/63 (63%) had baseline DEXA scans. 9/63 had a normal bone density. 21/63 had osteopenia, out of which 17/21 were treated. 10/63 had osteoporosis of which 5/10 were treated. Conclusions: Patients who are being treated with aromatase inhibitors should be evaluated for baseline bone health prior to initiating AIs and every 2 years thereafter. Treatment with bisphosphonates or RANK ligand inhibitors is recommended at an earlier T-score compared to post-menopausal osteoporosis in the absence of breast cancer. In our study, we noticed that the number of patients who did not receive a DEXA scan at the correct time points increased during the period of treatment with the AI. About 53% of patients had osteopenia or osteoporosis at the time of initiation of AIs. The amount of osteoporosis in patients increased from 9.5% at baseline to 15.8% at the 4-year point. This data indicates the need for proper guidelines on DEXA scans and interventions for this patient population. Current interventions planned are patient education Flyers, a patient risk factor checklist in the EMR (Electronic Medical Record) and prompts to review the status of the DEXA report when ordering AIs.

Complement receptor C5aR1 on osteoblasts regulates osteoclastogenesis in experimental postmenopausal osteoporosis.

In recent years, evidence has accumulated that the complement system, an integral part of innate immunity, may be involved in the regulation of bone homeostasis as well as inflammatory bone loss, for example, in rheumatoid arthritis and periodontitis. Complement may also contribute to osteoporosis development, but investigation of the mechanism is limited. Using mice with a conditional deletion of the complement anaphylatoxin receptor C5aR1, we here demonstrated that C5aR1 in osteoblasts (C5aR1 Runx2-Cre mice) or osteoclasts (C5aR1 LysM-Cre mice) did not affect physiological bone turnover or age-related bone loss in either sex, as confirmed by micro-computed tomography, histomorphometry, and biomechanical analyses of the bone and by the measurement of bone turnover markers in the blood serum. When female mice were subjected to ovariectomy (OVX), a common model for postmenopausal osteoporosis, significant bone loss was induced in C5aR1 fl/fl and C5aR1 LysM-Cre mice, as demonstrated by a significantly reduced bone volume fraction, trabecular number and thickness as well as an increased trabecular separation in the trabecular bone compartment. Confirming this, the osteoclast number and the receptor activator of nuclear factor k-B (RANK) ligand (RANKL) serum level were significantly elevated in these mouse lines. By contrast, C5aR1 Runx2-Cre mice were protected from bone loss after OVX and the serum RANKL concentration was not increased after OVX. These data suggested that bone cell-specific C5aR1 may be redundant in bone homeostasis regulation under physiological conditions. However, C5aR1 on osteoblasts was crucial for the induction of bone resorption under osteoporotic conditions by stimulating RANKL release, whereas C5aR1 on osteoclasts did not regulate OVX-induced bone loss. Therefore, our results implicate C5aR1 on osteoblasts as a potential target for treating postmenopausal osteoporosis.

The pathophysiologic basis of prostate cancer review

Worldwide, prostate cancer is the most commonly diagnosed malignancy and the sixth leading cause of cancer death in men. Diagnosis is primarily based on prostate-specific antigen (PSA) testing, MRI scans, and prostate tissue biopsies, although PSA testing for screening remains controversial. New diagnostic technologies including risk stratification bioassay tests, germline testing, and various PET scans are now available. When the cancer is limited to the prostate, it is considered localized and potentially curable. If the disease has spread outside the prostate, bisphosphonates, rank ligand inhibitors, hormonal treatment, chemotherapy, radiopharmaceuticals, immunotherapy, focused radiation, and other targeted therapies can be used. This activity is a current, comprehensive review of the evaluation and management of patients with prostate cancer and highlights the role of the interprofessional team in improving care for affected patients. Metastatic castration-resistant prostate cancer (mCRPC) remains a terminal diagnosis with an aggressive disease course despite currently approved therapeutics. Despite many recent advances in the therapy for metastatic castration-resistant prostate cancer (mCRPC), the disease remains incurable, although men suffering from this disease are living considerably longer.

An ankylosing spondylitis risk variant alters osteoclast differentiation.

To explore whether the variants in non MHC proteasome gene are associated with AS and explain the role of the variant in the disease. Case-control analysis to identify AS predisposition genes; dual-luciferase reporter assay, immunoblot analysis and osteoclastogenesis assays to detect the function of the positive variant. Affected individuals were diagnosed according to the modified New York Criteria by at least two experienced rheumatologists, and rechecked by another rheumatologist. The study included 1037 AS patients and 1014 no rheumatic and arthritis disease controls. The main age of AS onset is between 16 and 35 years old. HLA-B27-positive subjects comprised 90.0% of patients. A nonsynonymous SNP rs12717 in proteasome gene PSMB1 significantly associated with AS. Individuals with CC genotype had a higher onset risk compared with those with GG/GC genotypes (OR = 1.89, P = 0.0047). We also discovered that PSMB1 regulates the receptor activator of nuclear factor-κB (RANK)/RANK ligand (RANKL) signalling pathway and the disease-associated variant PSMB1-Pro11 significantly inhibits RANKL-induced NF-κB pathway in osteoclast differentiation via the degradation of IKK-β compared with PSMB1-Ala11. RANKL induced osteoclast differentiation was significantly lower in primary monocyte osteoclast precursor from individuals with genotype PSMB131C/31C compared with individuals with genotype PSMB131G/31G. These results reveal a novel understanding of the bone formation and reabsorbing imbalance in AS. The new bone formation phenotype can be attributed to the inhibition of osteoclast differentiation by a more functional PSMB1 gene.

Versicotide G suppresses osteoclastogenesis and prevents osteolysis

Excessive formation and function of osteoclasts cause various osteolytic bone diseases. Natural products are a potential source for the discovery of new therapeutic candidates to treat bone destruction diseases. In this study, chemical informatics and bioassay guided examination of the marine-derived Aspergillus versicolor F77 fungus chemically resulted in the isolation of seven cyclopeptides, of which versicotides G-J (1–4) are new cyclohexapeptides. Their structures were identified by spectroscopic data in association with Marfey method and single crystal X-ray diffraction data for configurational assignments. Bioassay revealed that versicotide G (1, VG) is the most active among the analogs to suppress the receptor activator of nuclear factor-KB ligand (RANKL)-induced osteoclastogenesis in bone marrow derived monocytes (BMMs) without affecting BMMs viability. VG also suppressed RANKL-induced actin-ring formation and resorbing function of osteoclast dose-dependently. Mechanistically, VG attenuated RANKL-induced intracellular calcium elevation by inhibiting PLCγ1 phosphorylation and blocking the activation of downstream phosphatase calcineurin. In addition, VG abrogated the expression and translocation of nuclear factor of activated T cells cytoplasmic-1 (NFATc1), leading to the downregulation of the expression of osteoclast-specific genes and the abolishment of the osteoclast formation. In the in vivo test, VG suppressed osteoclast formation and bone loss in Ti-induced calvarial osteolytic mouse model.These findings imply that VG is a promising candidate for the remedy of bone destruction-related diseases.

Lessons from the Failure to Complete a Trial of Denosumab in Women With a Pathogenic BRCA1/2 Variant Scheduling Risk-Reducing Salpingo-Oophorectomy.

Female carriers of pathogenic/likely pathogenic (P/LP) BRCA1/2 variants are at increased risk of developing breast and ovarian cancer. Currently, the only effective strategy for ovarian cancer risk reduction is risk-reducing bilateral salpingo-oophorectomy (RR-BSO), which carries adverse effects related to early menopause. There is ongoing investigation of inhibition of the RANK ligand (RANKL) with denosumab as a means of chemoprevention for breast cancer in carriers of BRCA1 P/LP variants. Through the NCI Division of Cancer Prevention (DCP) Early Phase Clinical Trials Prevention Consortia, a presurgical pilot study of denosumab was developed in premenopausal carriers of P/LP BRCA1/2 variants scheduled for RR-BSO with the goal of collecting valuable data on the biologic effects of denosumab on gynecologic tissue. The study was terminated early due to the inability to accrue participants. Challenges which impacted the conduct of this study included a study design with highly selective eligibility criteria and requirements and the COVID-19 pandemic. It is critical to reflect on these issues to enhance the successful completion of future prevention studies in individuals with hereditary cancer syndromes.

Guanylyl Cyclase-B Dependent Bone Formation in Mice is Associated with Youth, Increased Osteoblasts, and Decreased Osteoclasts.

C-type natriuretic peptide (CNP) activation of guanylyl cyclase-B (GC-B) catalyzes the synthesis of cGMP in chondrocytes and osteoblasts. Elevated cGMP stimulates long bone growth, and inactivating mutations in CNP or GC-B reduce cGMP, which causes dwarfism. GC-B7E/7E mice that express a GC-B mutant that cannot be inactivated by dephosphorylation exhibit increased CNP-dependent GC-B activity, which increases bone length, as well as bone mass and strength. Importantly, how GC-B increases bone mass is not known. Here, we injected 12-week-old, wild type mice once daily for 28days with or without BMN-111 (Vosoritide), a proteolytically resistant CNP analog. We found that BMN-111 treated mice had elevated levels of osteocalcin and collagen 1 C-terminal telopeptide (CTX) as well as increased osteoblasts and osteoclasts. In BMN-111 injected mice, tibial mRNAs for Rank ligand and osteoprotegrin were increased and decreased, respectively, whereas sclerostin mRNA was elevated 400-fold, consistent with increased osteoclast activity and decreased osteoblast activity. Mineral apposition rates and trabecular bone mass were not elevated in response to BMN-111. Because 9-week-old male GC-B7E/7E mice have increased bone mass but do not exhibit increased mineral apposition rates, we examined 4-week-old male GC-B7E/7E mice and found that these animals had increased serum osteocalcin, but not CTX. Importantly, tibias from these mice had 37% more osteoblasts, 26% fewer osteoclasts as well as 36% and 40% higher mineral apposition and bone formation rates, respectively. We conclude that GC-B-dependent bone formation is coupled to an early juvenile process that requires both increased osteoblasts and decreased osteoclasts.

Inhibitory Effect of Agrocybe Chaxingu (Chaxines) on RANKL-Induced Osteoclast Differentiation in RAW246.7 Cells: Possible Prevention of Osteoporosis

Objectives: Receptor-activator of nuclear factor-κB ligand (RANKL) is an essential stimulating factor for inducing osteoclast differentiation, feasibly resulting in osteoporosis. The bioactive extract of Agrocybe chaxingu mushroom, CHX, has been shown to have osteoclastic inhibitory activity. Accordingly, we investigated if CHX would inhibit or disrupt RANKL-induced osteoclast differentiation, implying possible prevention of osteoporosis. Materials and Methods: Monocyte/macrophage RAW264.7 cells (RAW cells) were employed as our experimental model and treated with varying concentrations of RANKL alone or with CHX for 5 days. Formation of osteoclasts was then assessed using tartrateresistant acid phosphatase (TRAP) assay, counting stained cells as osteoclasts under a light microscope. The inhibitory mechanism of CHX was also explored by examining the RANKLmediated signaling pathways, oxidative stress (OXS), antioxidant enzymes, and apoptosis. Results: RANKL (100 ng/mL)-induced osteoclast differentiation in RAW cells was significantly (~20%) inhibited with 10 μg/mL of CHX. This was accompanied by the downregulation of two key signaling pathways and activation of antioxidant enzymes that likely led to the reduction in OXS. Moreover, CHX ultimately induced undifferentiated or RANKLunresponsive cells to apoptosis, indicated by the modulation of apoptotic regulators. These findings may then account for a disruption of osteoclast differentiation with CHX. Conclusion: CHX appears to have the inhibitory effect on RANKL-induced osteoclast differentiation in RAW cells. It is thus plausible that CHX may have potential clinical implications in osteoclast-mediated bone diseases/disorders, including osteoporosis.

Denosumab versus zoledronic acid in cases of surgically unsalvageable giant cell tumor of bone: A randomized clinical trial

BackgroundGiant-cell tumor of bone (GCTB) is a relatively benign, but locally aggressive osteoclastogenic stromal tumour of the bone. Although denosumab has been approved as an monoclonal antibody against RANK ligand for the treatment of GCTB, few clinical trials of the benefit in tumor response have been conducted to prove the efficiency in Chinese population. ObjectivesIn this multicentric, random controlled, clinical trial, 160 patients were enrolled to compare the therapeutic efficacy and safety of denosumab and zoledronic acid treatment in patients with surgically unsalvageable GCTB. MethodsBetween 2nd Jan 2015 and 1st Jan 2018, 160 adults (aged ≥ 18 years) with ①surgically unsalvageable GCTB, ②surgically salvageable GCTB with planned surgery expected to result in severe morbidity were included in this randomized clinical trial. Patients received either subcutaneous denosumab (DB group; 120 mg once every 4 weeks with loading doses of 120 mg subcutaneously admininstered on days 8 and 15; n = 80) or intravenous zoledronic acid (ZA group; 4 mg once every 4 weeks; n = 80) for six cycles. Disease status, clinical benefits, treatment-emergent adverse effects, overall survival, and cost of treatment were evaluated during the follow-up period. Statistical significance was determined using 95% confidence intervals. ResultsDenosumab and zoledronic acid had similar tumor responses (p = 0.118) and clinical benefits (p = 0.574). Disease progression was observed in fewer patients in the DB group (12.5%) than ZA group (15.0%). Denosumab caused fatigue (p = 0.001) and back pain (p < 0.0001), while zoledronic acid caused hypocalcemia (p < 0.0001), flu-like symptoms (p = 0.059) and hypotension (p = 0.059). Denosumab treatment was markedly more expensive than zoledronic acid treatment (p < 0.0001). The cost to manage treatment-emergent adverse effects was the same for the ZA group and the DB group (p = 0.425). The accumulate recurrence-free survival rate at 4-year follow-up is higher in DB group (p = 0.035). ConclusionsDenosumab is a safe but costly alternative to zoledronic acid for treatment of surgically unsalvageable GCTB.

Melatonin inhibits osteoclastogenesis via RANKL/OPG suppression mediated by Rev‐Erbα in osteoblasts

Diabetic osteoporosis is secondary osteoporosis and a serious complication of diabetes with a high incidence rate and poor prognosis. The specific mechanism of diabetic osteoporosis is unclear, and prevention and treatment options are limited. Recently, melatonin has been found to prevent and treat diabetic osteoporosis. Herein, we investigated the mechanism whereby melatonin inhibits osteoclastogenesis and identified a new target for osteoporosis treatment. We established an in vitro osteoblast–osteoclast co‐culture system as a diabetic osteoporosis model. Osteoclastogenesis was determined using tartrate‐resistant acid phosphatase staining and cathepsin K expression. Real‐time PCR was used to ascertain expression of microRNA mir‐882, targeting Rev‐Erbα. Western blotting was performed to detect the expression of Rev‐Erbα, receptor activator of NF‐kB ligand (RANKL), and osteoprotegerin (OPG), and ELISA was utilized to analyse the secreted form of RANKL. High glucose promoted osteoclastogenesis and elevated the RANKL/OPG ratio in osteoblasts, while melatonin reversed these effects. High glucose inhibited Rev‐Erbα expression, while melatonin promoted its expression. Conversely, high glucose promoted mir‐882 expression, while melatonin inhibited it. We infer that melatonin inhibits RANKL expression in osteoblasts via the mir‐882/Rev‐Erbα axis, thus inhibiting osteoclastogenesis. Our findings provide insights into diabetic osteoporosis and identify a new therapeutic target for osteoporosis.

Molecular Pathways and Roles for Vitamin K2-7 as a Health-Beneficial Nutraceutical: Challenges and Opportunities.

Vitamin K2-7, also known as menaquinone-7 (MK-7) is a form of vitamin K that has health-beneficial effects in osteoporosis, cardiovascular disease, inflammation, cancer, Alzheimer’s disease, diabetes and peripheral neuropathy. Compared to vitamin K1 (phylloquinone), K2-7 is absorbed more readily and is more bioavailable. Clinical studies have unequivocally demonstrated the utility of vitamin K2-7 supplementation in ameliorating peripheral neuropathy, reducing bone fracture risk and improving cardiovascular health. We examine how undercarboxylated osteocalcin (ucOC) and matrix Gla protein (ucMGP) are converted to carboxylated forms (cOC and cMGP respectively) by K2-7 acting as a cofactor, thus facilitating the deposition of calcium in bones and preventing vascular calcification. K2-7 is beneficial in managing bone loss because it upregulates osteoprotegerin which is a decoy receptor for RANK ligand (RANKL) thus inhibiting bone resorption. We also review the evidence for the health-beneficial outcomes of K2-7 in diabetes, peripheral neuropathy and Alzheimer’s disease. In addition, we discuss the K2-7-mediated suppression of growth in cancer cells via cell-cycle arrest, autophagy and apoptosis. The mechanistic basis for the disease-modulating effects of K2-7 is mediated through various signal transduction pathways such as PI3K/AKT, MAP Kinase, JAK/STAT, NF-κB, etc. Interestingly, K2-7 is also responsible for suppression of proinflammatory mediators such as IL-1α, IL-1β and TNF-α. We elucidate various genes modulated by K2-7 as well as the clinical pharmacometrics of vitamin K2-7 including K2-7-mediated pharmacokinetics/pharmacodynamics (PK/PD). Further, we discuss the current status of clinical trials on K2-7 that shed light on dosing strategies for maximum health benefits. Taken together, this is a synthetic review that delineates the health-beneficial effects of K2-7 in a clinical setting, highlights the molecular basis for these effects, elucidates the clinical pharmacokinetics of K2-7, and underscores the need for K2-7 supplementation in the global diet.

Pim-2 regulates bone resorptive activity of osteoclasts via V-ATPase a3 isoform expression in periodontal disease.

Cytoplasmic serine/threonine Pim kinases have emerged as important modulators of immune regulation and oncology. However, their regulatory roles in bone remodeling remain obscure. Here, we aimed to determine the roles of Pim kinases in periodontal disease (PD), focusing on the regulation of osteoclastogenesis and bone resorptive activity. We investigated Pim kinases expression in PD by analyzing data from the online Gene Expression Omnibus database and using ligature-induced periodontitis mouse model. The expression of Pim kinases during receptor activator of nuclear factor kB ligand (RANKL)-induced osteoclastogenesis was assessed in mouse bone marrow-derived macrophages (BMMs) using reverse transcription polymerase chain reaction. Osteoclast differentiation and bone resorption activity were respectively verified by tartrate-resistant acid phosphatase staining and dentin disc-based bone resorption assays. We silenced and overexpressed Pim-2 using small interfering RNA (siRNA) and retroviral vector, respectively, to investigate the molecular mechanisms underlying Pim-2 regulation in RANKL-induced osteoclastogenesis and bone resorption activity. Upregulated expression of Pim-2 was observed in both patients with PD and periodontitis-affected mouse gingival tissues. siRNA-mediated silencing of Pim-2 in BMMs diminished RANKL-induced resorptive activity without affecting osteoclastogenesis. Moreover, RANKL-triggered stimulation of a3 isoform, which is a subunit of vacuolar-type ATPase, was selectively attenuated in BMMs on silencing Pim-2. The overexpression of Pim-2 with a retroviral vector stimulated the a3 subunit, thus inducing bone resorption activity. Taken together, these results suggest that Pim-2 acts as a major modulator of osteoclastic activity by regulating a3 isoform expression in PD.

Bone Turnover Marker (BTM) Changes after Denosumab in Giant Cell Tumors of Bone (GCTB): A Phase II Trial Correlative Study.

Simple SummaryGiant cell tumors of bone (GCTB) are a histologically benign, yet often aggressive, skeletal tumor. Surgery is the only potentially curative treatment option, but may be associated with severe morbidity and loss of function. Denosumab, a monoclonal antibody directed to RANK ligand, is approved for GCTB treatment. Here we report the results of a phase II correlative study on sBTMs (carboxytermnal-crosslinked-telopeptide of type I collagen (s-CTX), alkaline phosphatase (ALP), bone-alkaline phosphatase (bALP), parathyroid hormone (sPTH), and osteocalcin (OCN) in GCTB patients treated with denosumab. The main finding of the present research is that the use of denosumab in patients with GCTB induces the bALP/ALP/OCN and s-CTX reduction, with a concomitant increase in sPTH. High baseline s-CTX identifies a group of patients at higher risk of progression of the disease. Stratification of the GCTB patients based on s-CTX might guide type of surgery and follow-up.Background: Giant cell tumors of bone (GCTB) are osteolytic tumors. Denosumab, a RANK-L inhibitor, is approved for GCTB. Data on serum bone turnover marker (sBTM) changes are lacking. We present a phase II correlative study on sBTMs in GCTB patients treated with denosumab. Methods: All GCTB patients receiving denosumab within a multicentre, open-label, phase 2 study were enrolled. Serum levels of carboxyterminal-crosslinked-telopeptide of type I collagen (s-CTX), alkaline phosphatase (ALP), bone-alkaline phosphatase (bALP), parathyroid hormone (sPTH), and osteocalcin (OCN) were prospectively assessed (baseline, T0, 3 months, T1, 6 months, T2). The primary endpoint was assessment of sBTM changes after denosumab; the secondary endpoints were disease-free survival (DFS) and sBTM correlation. Results: In 54 cases, sBTMs decreased during denosumab treatment except for sPTH. With a median follow-up of 59 months, 3-year DFS was 65% (%CI 52–79), with a significantly worse outcome for patients with high (≥500 UI/mL) s-CTX at baseline, as compared to low s-CTX (<500 UI/mL) (3-year DFS for high CTX 45% (95%CI 23–67) vs. 75% (95%CI 59–91) for low s-CTX. Higher median ALP and s-CTX were found for patients with tumor size ≥ 5 cm (p = 0.0512; p = 0.0589). Conclusion: Denosumab induces ALP/OCN and s-CTX reduction. High baseline s-CTX identifies a group of patients at higher risk of progression of the disease.

LGR4, a G Protein-Coupled Receptor With a Systemic Role: From Development to Metabolic Regulation

Leucine-rich repeat-containing G protein-coupled receptor 4 (LGR4/GPR48), a member of the GPCR (G protein-coupled receptors) superfamily, subfamily B, is a common intestinal crypt stem cell marker. It binds R-spondins/Norrin as classical ligands and plays a crucial role in Wnt signaling potentiation. Interaction between LGR4 and R-spondins initiates many Wnt-driven developmental processes, e.g., kidney, eye, or reproductive tract formation, as well as intestinal crypt (Paneth) stem cell pool maintenance. Besides the well-described role of LGR4 in development, several novel functions of this receptor have recently been discovered. In this context, LGR4 was indicated to participate in TGFβ and NFκB signaling regulation in hematopoietic precursors and intestinal cells, respectively, and found to be a new, alternative receptor for RANKL (Receptor Activator of NF kappa B Ligand) in bone cells. LGR4 inhibits the process of osteoclast differentiation, by antagonizing the interaction between RANK (Receptor Activator of NF kappa B) and its ligand-RANKL. It is also known to trigger anti-inflammatory responses in different tissues (liver, intestine, cardiac cells, and skin), serve as a sensor of the circadian clock in the liver, regulate adipogenesis and energy expenditure in adipose tissue and skeletal muscles, respectively. The extracellular domain of LGR4 (LGR4-ECD) has emerged as a potential new therapeutic for osteoporosis and cancer. LGR4 integrates different signaling pathways and regulates various cellular processes vital for maintaining whole-body homeostasis. Yet, the role of LGR4 in many cell types (e.g. pancreatic beta cells) and diseases (e.g., diabetes) remains to be elucidated. Considering the broad spectrum of LGR4 actions, this review aims to discuss both canonical and novel roles of LGR4, with emphasis on emerging research directions focused on this receptor.

M299 A correlation between receptor activator of nuclear factor-kb ligand (RANKL) and osteoprotegerin (OPG) with bone mineral density (BMD)

M299 A correlation between receptor activator of nuclear factor-kb ligand (RANKL) and osteoprotegerin (OPG) with bone mineral density (BMD)

Alpha-7 Nicotinic Receptor Dampens Murine Osteoblastic Response to Inflammation and Age-Related Osteoarthritis

IntroductionOsteoarthritis (OA) is a whole-joint disease characterized by a low-grade inflammation that is involved in both cartilage degradation and subchondral bone remodeling. Since subchondral bone has a cholinergic innervation and that acetylcholine (Ach) might have an anti-inflammatory effect through the α7 nicotinic Ach receptor (α7nAchR), we aimed (i) to determine the expression of non-neuronal cholinergic system and nicotinic receptor subunits by murine and human osteoblasts, (ii) to address the role of α7nAchR in osteoblastic response to inflammation, and (iii) to study the role of α7nAchR in a spontaneous aging OA model.MethodsPrimary cultures of WT and α7nAchR knock-out mice (Chrna7-/-) murine osteoblasts and of subchondral bone human OA osteoblasts were performed. The expressions of the non-neuronal cholinergic system and of the nAchR subunits were assessed by PCR. In vitro, IL1β-stimulated WT, Chrna7-/-, and human osteoblasts were pretreated with nicotine. At 24 h, expressions of interleukin-6 (IL6) and metalloproteinase-3 and -13 (MMP), RANK-ligand (RANKL), and osteoprotegerin (OPG) were quantified by qPCR and ELISA. Spontaneous aging OA was evaluated and compared between male WT and Chrna7-/- mice of 9 and 12 months.ResultsMurine WT osteoblasts express the main components of the cholinergic system and α7 subunit composing α7nAchR. Nicotine partially prevented the IL1β-induced expression and production of IL6, MMP3, and RANKL in WT osteoblasts. The effect for IL6 and MMP was mediated by α7nAchR since nicotine had no effect on Chrna7-/- osteoblasts while the RANKL decrease persisted. Chrna7-/- mice displayed significantly higher cartilage lesions than their WT counterparts at 9 and 12 months, without difference in subchondral bone remodeling. Human OA osteoblasts also expressed the non-neuronal cholinergic system and α7 subunit as well as CHRFAM7A, the dominant negative duplicate of Chrna7. Nicotine pretreatment did not significantly reduce IL6 and MMP3 production in IL-1β-stimulated human osteoarthritic osteoblasts (n = 4), possibly due to CHRFAM7A.ConclusionCholinergic system counteracts murine osteoblastic response to IL-1β through α7nAchR. Since α7nAchR deletion may limit cartilage degradation during murine age-related OA, enhancing cholinergic system could be a new therapeutic target in OA but may depend on CHRFAM7A expression.