Serum Levels Of Receptor Activator Of Nuclear factor-kappaB Ligand Research Articles

Systemic Melatonin Supplementation as an Adjunct to Non-Surgical Periodontal Treatment in Obese Patients with Periodontitis

Background: Obesity is considered an important risk factor for periodontal disease. It has been reported that reactive oxygen species linking both diseases, systemic melatonin supplementation as antioxidant therapy, was addressed as an adjuvant to scaling and root surface debridement (SRP) to enhance the treatment of periodontitis. Objective: To investigate the efficacy of systemic melatonin administration in periodontitis-obese patients as an adjuvant to scaling and root surface debridement (SRP). Methods: A randomized clinical trial was conducted at a dental-specialized center. Eighty subjects were included and allocated into group-I: twenty periodontium-healthy, normal-weight people; group-II: 30 obese patients with stage-III treated only with SRP; and group-III: 30 obese patients with stage-III periodontitis treated with SRP and 5mg melatonin. periodontitis and subjected to estimation, serum levels of Receptor Activator of Nuclear Factor-Kappa B Ligand (RANKL) were estimated in all groups. Probing pocket depth (PPD), bleeding on probing (BOP), and relative attachment level (RAL) were estimated in Groups II and III at baseline and after a one-month visit. Results: RANKL baseline visits were significantly different between the control and studied groups, with no significant difference in clinical parameters except for PPD. The 2nd visit showed a significant difference in BOP score-1 compared to RAL and BOP score 0. In the second visit, only weak negative and positive significant correlations were found between RANKL and BOP. Conclusion: Daily use of 5 mg of melatonin improves periodontal parameters and decreases serum RANKL levels.

Inflammation is responsible for systemic bone loss in patients with seropositive rheumatoid arthritis treated with rituximab.

We investigated the effect of rituximab on systemic bone metabolism in patients with seropositive rheumatoid arthritis (RA). Twenty seropositive patients with RA were enrolled and administered one cycle of rituximab. If RA became active for > 6 months after the first rituximab cycle, a second cycle was initiated; otherwise, no additional treatment was administered. Patients were divided into two groups according to the number of rituximab treatment cycles. In patients treated with a second cycle, the total hip bone mineral density (BMD) was clinically low, whereas the serum levels of receptor activator of nuclear factor kappa-B ligand (RANKL) were increased at 12 months. BMD in patients treated with one cycle did not change at 12 months, whereas serum RANKL levels decreased at all time points. DAS28 activity improved in both groups from baseline to 4 months; however, from 4 to 12 months, DAS28 activity worsened in the develgroup with the second cycle but remained stable in the group with one cycle. Systemic inflammation, reflected by increased disease activity, may be responsible for the increase in RANKL levels, which causes systemic bone loss in rituximab-treated patients with RA. Although rituximab affects inflammation, it does not seem to alter systemic bone metabolism in RA.

Interleukin-21 knockout reduces bone loss in ovariectomized mice by inhibiting osteoclastogenesis.

Estrogen deficiency accelerates osteoporosis in elderly women. However, the role of IL-21 in postmenopausal osteoporosis remains unclear. Female wild-type (WT) C57BL/6 and IL-21 knockout (KO) mice were used for ovariectomy (OVX). Here, IL-21 levels were significantly increased in the serum and bone tissues of WT-OVX mice. The trabecular bone space of the femur was significantly increased, and the bone mass was reduced in OVX mice, accompanied by a significant decrease in the maximum load, energy absorption, and elastic modulus indices. In contrast, IL-21 knockout effectively alleviated the effects of OVX on bone mass. Serum TRACP-5b and receptor activator of nuclear factor kappa B ligand (RANKL) levels and osteoclastogenesis were significantly higher in OVX mice than in sham mice, while serum TRACP-5b and RANKL levels and osteoclastogenesis were significantly decreased in IL-21 KO+OVX mice compared to WT+OVX mice. IL-21 knockdown reduces TRACP-5b, RANKL, and osteoclastogenesis, effectively preventing bone resorption and alleviating the progression of OVX-induced osteoporosis.

Cystic fibrosis related bone disease in children: Can it be predicted?

Cystic fibrosis (CF) -related bone disease (CFBD) is an important complication of CF, and low BMD in childhood is a precursor of CFBD. Here, we aimed to investigate bone turnover biomarkers, including osteocalcin (OC), receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) in relation to low BMD in children with CF (cwCF). We also evaluated factors which could affect bone turnover with particular emphasis on fat-free mass (FFM), forced expiratory volume in 1s (FEV1), hand grip strength (HGS), and functional capacity and physical activity. Sixteen cwCF aged 8-18 years with moderate low BMD (group1) and 64 cwCF with normal BMD (group2) were enrolled. Serum RANKL, OC, and OPG were determined by immunoenzymatic assays. Multiple parameters including pancreatic status, lung functions, body mass index (BMI), FFM measured by bioelectric impedance analysis (BIA), 6-minute walk test, vitamin D, nutritional intake, HGS, functional capacity and physical activity, serum and urine biomarkers were compared between the two groups. We found similar serum levels of RANKL (p=0.501), OC (p=0.445), OPG (p=0.380), and RANKL/OPG ratio (p=0.449) between group1 and group2 in cwCF. BMI z-score (p<0.001), FFMI z-score (p<0.001), FEV1 z-score (p=0.007), and right-HGS (%pred) (p=0.009) significantly differed between the two groups. Multivariate linear regression revealed that the only factors that predicted BMD were FFMI z-score and HGS %pred. Serum OC, OPG, RANKL and RANKL/OPG ratio did not predict BMD in cwCF. FFMI z-score and HGS %pred measured by non-invasive and practical methods were the best predictors of BMD.

OPG/RANK/RANKL Axis in Egyptian Children With Acute Lymphoblastic Leukemia After Maintenance Therapy: Relationship to Bone Mineral and Vitamin D Status.

Policies to maximize peak bone mass in survivor's children of acute lymphoblastic leukemia (ALL) have been recognized as a priority area for research. The present study aimed to evaluate the relationship between osteoprotegerin (OPG)/receptor activator of nuclear factor kappa-B (RANK)/RANK ligand (RANKL) axis, vitamin D status, and serum magnesium in ALL survivors. Sixty ALL survivors treated with chemotherapy and 60 age and sex-matched controls were included. Vitamin D and parathyroid hormone, RANK, RANKL, and OPG levels were immunoassayed, in addition to serum calcium, phosphorus, magnesium levels, and alkaline phosphatase activity assessment. Furthermore, standard anthropometric measurement, history of fractures since treatment and clinical assessment were recorded. History of bone fractures after the start of therapy was detected in 17 ALL subjects (28.33%). Significantly lower vitamin D, magnesium, calcium, and OPG levels, meanwhile, significantly higher serum parathyroid hormone, RANK, and RANKL levels were detected in survivors compared with the control group. Vitamin D level was significantly positively correlated with magnesium, calcium, and OPG levels. Meanwhile, negatively correlated with RANK and RANKL levels. ALL survivors had a high prevalence of impaired vitamin D status, decreased Mg, and altered OPG/RANK/RANKL axis with impaired bone remodeling. The results herein may open the door for new interventional actions in ALL survivors to protect against bone resorption.

QiangGuYin Modulates the OPG/RANKL/RANK Pathway by Increasing Secretin Levels during Treatment of Primary Type I Osteoporosis.

QiangGuYin (QGY) is a common Traditional Chinese medicine prescription for the treatment of osteoporosis. Previous clinical studies have found that QGY effectively improves bone mineral density (BMD) in postmenopausal women, but its underlying mechanism remains unclear. The osteoprotegerin (OPG)/receptor activator of nuclear factor kappa B ligand (RANKL)/receptor activator of nuclear factor kappa B (RANK) pathway is a classic pathway involved in osteoporosis. Secretin levels are a serum marker of osteoporosis, but their effect on the OPG/RANKL/RANK pathway has not been reported. Hence, we investigated the relationship between the OPG/RANKL/RANK pathway and secretin and further revealed the mechanism underlying the effect of QGY in the treatment of osteoporosis. Mice were divided into secretin knockdown, secretin overexpression, and corresponding control groups. Micro-computed tomography was used to detect BMD in different groups, and the results show that QGY significantly improved BMD in mice of the secretin knockdown group. To further verify this, the serum levels of OPG, RANKL, RANK, and secretin were measured by enzyme-linked immunosorbent assays, and femur levels of OPG, RANKL, RANK, and secretin were evaluated by real-time quantitative PCR and western blotting. The results show that the expression of OPG was inhibited and that of RANKL and RANK was increased in mice from the secretin knockdown group, whereas the expression of OPG was upregulated and that of RANKL and RANK was downregulated after QGY intervention. Therefore, QGY inhibited bone resorption by promoting the expression of secretin and modulating the OPG/RANKL/RANK pathway. In addition to the effect of QGY, we also revealed the general regulatory effect of secretin on the OPG/RANKL/RANK pathway. We conclude that QGY modulates the OPG/RANKL/RANK pathway by increasing secretin levels during treatment of primary type I osteoporosis. This work provides a theoretical basis for the clinical use of QGY in the treatment of osteoporosis.

Bone health in pediatric transfusion-dependent beta-thalassemia: Circulating osteoprotegerin and RANKL system.

While the mechanism of bone disease in thalassemia is multifactorial and still under investigation, the receptor activator of nuclear factor kappa B (RANK), receptor activator of nuclear factor kappa B ligand (RANKL), and osteoprotegerin (OPG) have pivotal roles in regulating bone metabolism. This study aimed to measure RANKL and OPG serum levels, and to detect the incidence of RANKL rs9533156, OPG rs2073618, and OPG rs2073617 genotypes in pediatric β-thalassemia patients and to assess their relation to bone mineral density. Sixty patients with transfusion-dependent β-thalassemia (TBT) patients ages 5 to 14 years were included, and 60 healthy, age- and sex-matched volunteers contributed as a control group. The patients were scanned for bone mineral density. The mean of spine dual-energy X-ray absorptiometry (DXA) Z-score in patients was -1.66 ± 1.02 standard deviation (SD). Twenty-four of them had low spine DXA Z-scores. The patients showed significantly lower OPG levels and OPG/RANKLs ratios than the control group (3.28 ± 9.11ng/ml and 11.38 ± 14.93ng/ml, and 0.01 ± 0.03 and 0.07 ± 0.09, respectively). The RANKL SNP rs9533156 TC heterozygous genotype was detected more with statistical significance in patients than controls. The incidence of OPG rs2073618 and OPG rs2073617 genotypes were 2.3 times and 1.9 times more frequent in patients than controls, respectively. The RANK/RANKL/OPG system may have an important role in regulating bone metabolism in TBT patients, although further studies are needed to clarify its role.

The Relationship between Serum and Gene Expression Levels of RANK, RANKL and Osteoprotegerin Inflammatory Pathway with Unstable Angina: A Case-control Study

Osteoprotegerin (OPG), receptor activator of nuclear factor-kappa B (RANK) and receptor activator of nuclear factor-kappa B ligand (RANKL), the members of the tumor necrosis factor (TNF) family, have multiple effects on bone metabolism, endocrine functions and, as an inflammatory pathway, in the immune system. This study tried to determine the association of the OPG/RANKL/RANK axis with the severity of unstable angina (UA) as an inflammatory condition. Our study involved 50 patients with UA and 50 healthy people. Serum and peripheral blood mononuclear cells were isolated from all participants. Serum levels and gene expression of OPG, RANKL, and RANK in mononuclear cells were measured by enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (RT-PCR), respectively. For each patient with UA, the thrombolysis in myocardial infarction (TIMI) and the global registry of acute coronary events (GRACE) scores were determined to evaluate the severity of the disease. Then we analyzed the relation of OPG, RANKL, and RANK levels with TIMI and GRACE scores in patients with UA. Discriminate analysis was used to predict the combinational models of such factors on the prediction of UA. Serum levels of OPG and RANKL (p<0.001) and gene expression of RANKL (p<0.001) were significantly more in patients than those in healthy ones. No relation was seen between the OPG/RANKL/RANK axis and the severity of UA according to TIMI and GRACE scores. Our study shows that serum level, as well as gene expression of OPG/RANKL/RANK axis neither, predicts the occurrence of UA nor shows any relationship with its severity.

ETS1 polymorphism rs73013527 in relation to serum RANKL levels among patients with RA.

We previously identified E26 transformation specific sequence 1 (ETS1) rs73013527 single nucleotide polymorphism associated with RA susceptibility and disease activity. In the present study, we aims to further investigate the association between ETS1 rs73013527 and receptor activator of nuclear factor kappa B ligand (RANKL), an index related to bone destruction and was reported to elevate in RA.We determined genotypes of ETS1 rs73013527, serum RANKL concentration, clinical characteristics (disease duration, disease activity score for 28 painful/swollen joints), and laboratory markers (rheumatoid factor, anti-citrullinated protein antibody, anti-keratin antibody, c-reactive protein, erythrocyte sedimentation rate) of 254 RA cases. Univariate and multivariate analysis were employed to explore the association between ETS1 rs73013527 and serum RANKL levels in RA patients.Univariate and multivariate analysis indicated no association of serum RANKL levels with patient age, gender, clinical characteristics, and laboratory markers. Univariate analysis, not multivariate analysis indicated genotype CT/TT of ETS1 rs73013527 was significantly associated with elevated RANKL levels in RA patients.ETS1 rs73013527 is in relation to serum RANKL levels among patients with RA. ETS1 probably might be an indirect factors involved in RANKL regulation in RA.

Association of Receptor Activator of Nuclear Factor-κB Ligand (RANKL) and Osteoprotegerin with Secondary Hypogonadism in Egyptian Females with Beta-Thalassemia Major

Background: Thalassemia is the most common cause of chronic hemolytic anemia and is correlated with significant morbidity and mortality. Osteoprotegerin (OPG) is an α tumor necrosis factor receptor superfamily glycoprotein that acts as a decoy receptor for the receptor activator of nuclear factor kappa B ligand (RANKL), exerting an antiresorptive bone effect and also play critical roles in hypogonadism associated osteoporosis. Objective: Toexplore the serum levels of RANKL and OPG in adult Egyptian females with Beta-Thalassemia Major (BTM) and to detect their relations with female hypogonadism Patients and Methods: a prospective cross-sectional controlled study enrolled 50 control females and 45 women with BTM. We measured OPG and RANKL by ELISA, Bone mineral density (BMD) of the lumbar spine and femoral neck was measured by dual-energy X-ray absorptiometry Results: Among 45 patients with BTM, 27 patients had hypogonadotropic hypogonadism, and they had significantly higher values of serum RANKL (8.3±1.8pmol/l) compared to BTM without hypogonadism (5.9±1.01) and controls (5.5±1.11). Regarding serum OPG, there were no non-significant differences between the studied groups. Linear regression analysis test revealed that serum RANKL levels were independently correlated with BMD femur and spine, while serum OPG levels were independently correlated with BMD spine and LH. The sensitivities and the specificities of serum RANKL levels by ROC tests to discriminate against BTM patients with hypogonadism were 91.1% and 96%. Conclusions: Serum RANK levels elevated in BTM patients particularly hypogonadism groups. The diagnostic power of serum RANKL was highly significant thus, it could be used as a biological marker of hypogonadism in BTM.

Effects of moxibustion on serum cytokines in experimental animals with rheumatoid arthritis: a systematic review and meta-analysis

To systematically review the effects of moxibustion on serum cytokines in experimental animals with rheumatoid arthritis. PubMed, Embase, Web of Science, The Cochrane Library, CNKI, VIP, Wanfang Data, and CBM were searched for animal experiments on moxibustion intervention for rheumatoid arthritis. Related data were extracted, and RevMan 5.3 was used to perform a meta-analysis of outcome measures, including serum tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), interleukin-17 (IL-17), interleukin-2 (IL-2), interferon-γ (IFN-γ), receptor activator of nuclear factor-kappa B ligand (RANKL), transforming growth factor-β (TGF-β), and degree of swelling of diseased joint. A total of 18 studies were included. The detection methods included radioimmunoassay and ELISA and the experimental animal species included rats and rabbits. The studies on serum TNF-α and degree of swelling of diseased joint had publication bias. Meta-analysis showed that the moxibustion group had significant reductions in the serum levels of TNF-α, IL-1, IL-2, IL-6, VEGF, IL-17, and RANKL, significant increases in the serum levels of TGF-β and IFN-γ, and a significant reduction in the degree of swelling of diseased joints in model animals. Moxibustion can effectively regulate levels of the serum cytokines in experimental animals of rheumatoid arthritis and thus reduce inflammatory response and alleviate the swelling of diseased joints.

Metformin Reduces Thyroid Cancer Tumor Growth in the Metastatic Niche of Bone by Inhibiting Osteoblastic RANKL Productions.

Background: Metformin has antitumoral actions in human cancers, including the thyroid, while its effects on metastatic lesions are unclear. Patients with bone metastasis (BM) from thyroid cancers have poor survival. Because metformin inhibits the activation of osteoclasts, which has essential roles in BM, the aim of this study was to investigate the therapeutic effects of metformin on thyroid cancer BM and osteoclast activation in the bone microenvironment. Methods: The anaplastic thyroid cancer (ATC) cell lines FRO and SW1736 were used to test the antitumoral effect of metformin in vitro and in vivo. A murine model of BM was established by intratibial injection of cancer cells. To mimic the BM microenvironment, osteoblasts were treated with conditioned media from the FRO (FRO-CM) and SW1736 (SW1736-CM) cells. Thyroid cancer patients with or without BM were recruited, and the serum receptor activator of nuclear factor kappa-B ligand (RANKL) levels was measured. Results: Metformin treatment significantly reduced the viabilities of the FRO and SW1736 cells in vitro and the tumor growth of SW1736 in vivo. In the murine model of BM, metformin delayed tumor growth in the bone and decreased the numbers of tartrate-resistant acid phosphatase-positive osteoclasts on the bone surface with reduced RANKL in the bone marrow. Furthermore, FRO- or SW1736-CM significantly increased the osteoblastic RANKL productions and activated osteoclast differentiation in whole marrow cultures, which were blocked by metformin treatment. Among 67 thyroid cancer patients, the serum RANKL levels were significantly increased in BM patients compared with patients with lung-only metastasis or no distant metastasis. In addition, the interleukin-6 superfamily in the FRO- or SW1736-CM stimulated STAT3 phosphorylation, which was inhibited by gp130 blocking. Metformin treatment decreased the FRO- or SW1736-CM-induced STAT3 phosphorylation by AMPK phosphorylation. Metformin also inhibited the FRO- or SW1736-CM-induced osteoclastic differentiation of bone marrow-derived monocyte/macrophage by RANK/c-Fos/NFATC1 signaling. Conclusions: In the microenvironment of BM, metformin effectively reduced ATC tumor growth by inhibiting cancer cell viability, blocking cancer cell-induced osteoblastic RANKL production, which further activated osteoclastogenesis, and directly reduced osteoclast differentiation. These multifactorial actions of metformin suggest that it has potential therapeutic effects in thyroid cancer BM.

Effects of Drynaria Total Flavonoid on the Microstructure of the Mandible in Ovariectomized Rats.

BackgroundThe aim of this study is to investigate the effects of Drynaria total flavonoids (DTF) on mandible microarchitecture, serum estrogen (E2), osteoprotegerin (OPG), and receptor activator of nuclear factor kappa-B ligand (RANKL) levels in an ovariectomy-induced osteoporosis rat model.Material/MethodsThirty female Sprague-Dawley rats were divided into 5 groups (n=6 per group): sham surgery, ovariectomy (OVX), and low-dose, middle-dose, and high-dose DTF. Mandibular osteoporosis was induced by ovariectomy; an equal amount of ovary-sized fat tissue was removed from the sham group. The DTF-treated groups were given DTF gavage at different doses for 12 weeks; the sham and OVX groups were given saline. After the treatment phase, the effects of DTF on the microarchitecture of the mandible were evaluated by measuring bone density, maximum load, morphometric parameters, and histopathological alterations. Serum E2, OPG, and RANKL levels were measured.ResultsThe OVX group showed obvious osteoporosis in the mandible and decreased serum E2 levels and OPG/RANKL ratio. The low-dose group did not show significant improvement in mandibular microstructure. The middle-dose group showed significantly ameliorated osteoporosis. The high-dose group had further improvement in bone microstructures and increase of OPG/RANKL over the middle-dose group. Furthermore, ovariectomy significantly decreased serum E2, but DTF treatment failed to restore serum E2 levels.ConclusionsOvariectomy can cause significant bone loss in the rat mandible and a decrease in serum E2 and OPG/RANKL. DTF significantly improved the mandibular microstructure and restored OPG/RANKL balance, but it did not restore the decreased serum E2 concentration following ovariectomy.

Associations of Bone Turnover Markers with Cognitive Function in Patients Undergoing Hemodialysis.

Background Patients undergoing hemodialysis experience a greater risk of cognitive impairment than the general population, but limited data elucidates the biomarkers on this. We evaluated the association of bone turnover markers on cognitive function among 251 prevalent hemodialysis enrollees in a cross-sectional study. Methods 251 hemodialysis patients (median age = 57.8, 55% men) and 37 control subjects (mean age = 61.2, 56% men) without a prior stroke or dementia diagnosis were enrolled. Serum concentrations of 8 bone markers were analyzed as the association of cognitive function (Montreal Cognitive Assessment (MoCA) and Cognitive Abilities Screening Instrument (CASI)) using linear regression analysis. Results A lower cognitive function was noted in hemodialysis patients compared to control subjects. The receptor activator of nuclear factor kappa-B ligand (RANKL) was the only bone marker found to be associated with cognitive function (MoCA and CASI tests) in hemodialysis patients without a prior stroke or dementia diagnosis. In stepwise multiple linear regression analysis, the association remained significant in MoCA (β = 1.14, 95% CI 0.17 to 2.11) and CASI (β = 3.06, 95% CI 0.24 to 5.88). Short-term memory (β = 0.52, 95% CI 0.01 to 1.02), mental manipulation (β = 0.51, 95% CI 0.05 to 0.96), and abstract thinking (β = 0.57, 95% CI 0.06 to 1.09) were the significant subdomains in the CASI score related to RANKL. Conclusions Serum RANKL levels were potentially associated with better cognitive function in hemodialysis patients. Further large-scale and prospective studies are needed to confirm our findings.

OPG/RANK/RANKL signaling axis in patients with type I diabetes: Associations with parathormone and vitamin D

BackgroundType 1 diabetes (T1D) has been associated with a higher fracture risk due to alterations in bone structure and metabolism. On the other hand, the important role of the RANKL/OPG/RANK signaling axis in bone physiology is well established. The aim of this study was to evaluate the levels of receptor activator of nuclear factor kappa-B ligand (RANKL), receptor activator of nuclear factor kappa-B (RANK) and plasma osteoprotegerin (OPG) levels, in T1D youngsters and to investigate factors that could influence the OPG/RANK/RANKL signaling axis such as 25-hydroxy vitamin D [25(OH) D], parathormone (PTH) and age.MethodsSerum RANKL, RANK, 25(OH) D, PTH levels and plasma OPG levels, were measured in 71 youngsters with T1D and 50 healthy controls matched for age and gender.ResultsPlasma OPG levels were significantly lower (p = 0.025) in T1D patients compared to controls. Serum RANKL levels were significantly higher (p = 0.037), while no differences were observed in serum RANK levels (p = 0.946) between the two groups. Serum 25(OH) D levels found significantly decreased (p < 0.001) while serum PTH levels were significantly elevated (p < 0.001) in T1D patients than in controls.ConclusionsOur results demonstrated that OPG and RANKL may be promising biomarkers for T1D patients. However, their circulating levels were associated with several factors including PTH, 25(OH) D and therefore, may represent an integrative biomarker for a variety of endocrine signaling disturbances observed in T1D.

Abaloparatide exhibits greater osteoanabolic response and higher cAMP stimulation and β-arrestin recruitment than teriparatide.

Teriparatide and abaloparatide are parathyroid hormone receptor 1 (PTHR1) analogs with unexplained differential efficacy for the treatment of osteoporosis. Therefore, we compared the effects of abaloparatide and teriparatide on bone structure, turnover, and levels of receptor activator of nuclear factor‐kappa B ligand (RANKL) and osteoprotegerin (OPG). Wild‐type (WT) female mice were injected daily with vehicle or 20–80 µg/kg/day of teriparatide or abaloparatide for 30 days. Femurs and spines were examined by microcomputed tomography scanning and serum levels of bone turnover markers, RANKL, and OPG, were measured by ELISA. Both analogs similarly increased the distal femoral fractional trabecular bone volume, connectivity, and number, and reduced the structure model index (SMI) at 20–80 µg/kg/day doses. However, only abaloparatide exhibited a significant increase (13%) in trabecular thickness at 20 µg/kg/day dose. Femoral cortical evaluation showed that abaloparatide caused a greater dose‐dependent increase in cortical thickness than teriparatide. Both teriparatide and abaloparatide increased lumbar 5 vertebral trabecular connectivity but had no or modest effect on other indices. Biochemical analysis demonstrated that abaloparatide promoted greater elevation of procollagen type 1 intact N‐terminal propeptide, a bone formation marker, and tartrate‐resistant acid phosphatase 5b levels, a bone resorption marker, and lowered the RANKL/OPG ratio. Furthermore, PTHR1 signaling was compared in cells treated with 0–100 nmol/L analog. Interestingly, abaloparatide had a markedly lower EC50 for cAMP formation (2.3‐fold) and β‐arrestin recruitment (1.6‐fold) than teriparatide. Therefore, abaloparatide‐improved efficacy can be attributed to enhanced bone formation and cortical structure, reduced RANKL/OPG ratio, and amplified Gs‐cAMP and β‐arrestin signaling.

Monomethylfumarate protects against ovariectomy-related changes in body composition.

Osteoporosis, low bone mass that increases fracture susceptibility, affects approximately 75 million individuals in the United States, Europe and Japan, with the number of osteoporotic fractures expected to increase by more than 3-fold over the next 50 years. Bone mass declines with age, although the mechanisms for this decrease are unclear. Aging enhances production of reactive oxygen species, which can affect bone formation and breakdown. The multiple sclerosis drug Tecfidera contains dimethylfumarate, which is rapidly metabolized to monomethylfumarate (MMF); MMF is thought to function through nuclear factor erythroid-derived-2-like-2 (Nrf2), a transcription factor activated by oxidative stress which induces the expression of endogenous anti-oxidant systems. We hypothesized that MMF-elicited increases in anti-oxidants would inhibit osteopenia induced by ovariectomy, as a model of aging-related osteoporosis and high oxidative stress. We demonstrated that MMF activated Nrf2 and induced anti-oxidant Nrf2 target gene expression in bone marrow-derived mesenchymal stem cells. Sham-operated or ovariectomized adult female mice were fed chow with or without MMF and various parameters monitored. Ovariectomy produced the expected effects, decreasing bone mineral density and increasing body weight, fat mass, bone marrow adiposity and serum receptor activator of nuclear factor-kappa-B ligand (RANKL) levels. MMF decreased fat but not lean mass. MMF improved trabecular bone microarchitecture after adjustment for body weight, although the unadjusted data showed few differences; MMF also tended to increase adjusted cortical bone and to reduce bone marrow adiposity and serum RANKL levels. Because these results suggest the possibility that MMF might be beneficial for bone, further investigation seems warranted.

Changes in Dkk-1, sclerostin, and RANKL serum levels following discontinuation of long-term denosumab treatment in postmenopausal women.

The positive effects of denosumab (DMAb) on bone mineral density (BMD) are quickly reversible after its discontinuation. We investigated whether this rebound was associated with dysregulation of the Wnt canonical pathway and/or by the increase in the receptor-activator of nuclear factor-kappa B ligand (RANKL) serum levels. The study included patients (n = 15) with postmenopausal osteoporosis to whom DMAb was administered for 78 months and then discontinued. We collected BMD data at baseline/month 0 (M0), M60, M84 (6 months after last DMAb administration, coinciding when the next DMAb dose would typically be due), and after 3 and 12 months of follow-up (FU-M3 and FU-M12, respectively). Serum C-terminal telopeptide of type 1 collagen (CTX-I), Dickkopf-1 (Dkk-1), and sclerostin were measured at M0, M60, M84, FU-M3, and FU-M12. Serum N-terminal propeptide of type 1 procollagen (PINP) and RANKL were dosed at M60, M84, FU-M3, and FU-12. We found a significant decrease in the T-score at all sites at FU-M12, when compared to M84 (-0.51 ± 0.91 at the lumbar spine; -0.72 ± 0.33 at the total hip; and -0.42 ± 0.27 at the femoral neck, p < 0.05). After DMAb discontinuation (M84 vs FU M12) CTX-I, PINP increased already at FU-M3 (+0.921 ± 0.482 ng/mL, +126.60 ± 30.36 ng/mL, respectively, p < 0.01), RANKL increased at FU-M12 (+0.041 ± 0.062 ng/mL, p < 0.05), while Dkk-1 and sclerostin decreased at FU-M12 (-10.90 ± 11.80 and - 13.00 ± 10.52 pmol/L, respectively, p < 0.01). No changes in BMD or any of the markers were found between M60 and M84. RANKL serum levels progressively increased after discontinuation of long-term DMAb while Dkk-1 and sclerostin serum levels decreased. The increase in RANKL serum levels supports the hypothesis of a sudden loss of inhibition of the resting osteoclast line after DMAb clearance, with a hyperactivation of these cells. Our results suggest that the changes in serum Wnt inhibitors after DMAb suspension might represent a mere feedback response to the increased bone turnover.

Abstract P6-09-01: In primary, non-metastatic breast cancer patients, increased serum levels of RANKL significantly correlate with tumor cell spread to the bone and the occurrence of bone metastasis whereas high levels of its soluble decoy receptor osteoprotegerin predict poor survival

Abstract Background: Receptor activator of nuclear factor kappa-B ligand (RANKL) is an essential protein for osteoclast regulation and its activity is controlled by its soluble decoy receptor osteoprotegerin (OPG). RANKL has been associated with benign as well as malignant bone disease and there is increasing evidence that RANKL may also directly affect breast cancer (BC) progression and metastasis to the bone. Here we assessed serum concentrations of RANKL and OPG in 509 patients with primary, non-metastatic BC and correlated the results with clinical parameters including the presence of disseminated tumor cells (DTCs) in the bone marrow (BM), survival and the risk of developing metastatic disease. Patients and Methods: Patients with first diagnosis of BC between Aug 2006 and Dec 2009 were included in our study. BM sampling was performed before surgery in an adjuvant setting and two BM aspirates were analyzed for DTCs using density centrifugation followed by immunocytochemistry applying the pan-cytokeratin antibody A45-B/B3. Blood was collected from each patient and sRANKL and OPG levels in the serum were measured by ELISA (Biomedica, Vienna, Austria). Results: Mean serum values for RANKL and OPG were 0.23±0.20 pmol/l and 4.24±1.70 pmol/l, respectively. RANKL levels were significantly lower in women above the age of 60 (p&amp;lt;0.0001) and RANKL/OPG ratios were higher in patients with lymph node involvement (p&amp;lt;0.05). High OPG levels were associated with a higher risk of death from BC (HR 1.94 95%CI 1.23-3.07; p=0.005) and multivariate analyses revealed OPG to be an independent prognostic marker for BC specific survival (p=0.035). DTCs were detected in 207/507 (41%) patients and RANKL levels were 33% higher in DTC-positive patients (p&amp;lt;0.0001). Interestingly, in DTC-negative patients, high RANKL levels were associated with a significantly better BC specific survival compared to low levels (HR 0.524; 95%CI 0.30-0.95; p=0.04). RANKL serum levels were significantly enhanced in patients that developed bone metastases (p=0.01) and patients in the highest quartile of RANKL had a significantly increased risk of developing bone metastases compared to those in the lowest RANKL quartile (HR 4.62, 95%CI 1.49-14.34, p=0.03). Conclusion: Increased OPG levels indicated poor survival and high RANKL significantly associated with an increased risk of developing bone metastases while indicating a positive prognostic marker in DTC-negative patients. These findings warrant further investigation as it may provide a rational for novel diagnostic or therapeutic approaches. Citation Format: Bittner A-K, Goebel A, Hoffmann O, Rauner M, Hofbauer LC, Kimmig R, Kasimir-Bauer S, Rachner TD. In primary, non-metastatic breast cancer patients, increased serum levels of RANKL significantly correlate with tumor cell spread to the bone and the occurrence of bone metastasis whereas high levels of its soluble decoy receptor osteoprotegerin predict poor survival [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-09-01.

Evaluation of bone formation using recombinant human bone morphogenetic proteins-7 in small maxillofacial bony defects.

Context:Bone morphogenetic proteins (BMP) are multifunctional molecules of transforming growth factor-β superfamily that induces the differentiation of fibroblasts into osteoblasts to form bone.Aims:This study was undertaken to evaluate the effects of recombinant human BMP-7 (rhBMP-7) in bone healing of small maxillofacial bone defects and assess the serum levels of osteopontin (OPN) and receptor activator of nuclear factor kappa-B ligand (RANKL) biomarkers for bone remodeling.Materials and Methods:Twenty patients with small maxillofacial bony defects were enrolled in this study and randomly allocated to two groups; wherein after apicoectomy of the involved teeth, the control group had defect filled with collagen sponge only while the experimental group had rhBMP-7 impregnated collagen sponge placed in the defect.Results:The clinical parameters showed no significant difference between the two groups (P > 0.05). The radiographic parameters showed a significantly slower rate of reduction in bone defect volume (P < 0.01) in control group than the experimental group when followed at 2, 4 and 24 postoperative weeks. RANKL and OPN serum levels showed no significant changes in pre- and post-operative stage.Conclusion:This study confirms that rhBMP-7 in collagen definitely accelerates bone healing in maxillofacial bone defects and minimizes postoperative complications. RANKL and OPN biomarkers in serum may not show bone remodeling, hence tissue samples may be used to assess their levels.