Serum levels of osteoprotegerin increase with age in a healthy adult population

Vertebral marrow fat fraction is associated with circulating RANKL in postmenopausal females

Objective

To investigate the relationship between circulating receptor activator of nuclear factor-kappa B ligand (RANKL) levels and marrow adipose tissue in postmenopausal females.

Methods

A total of 164 postmenopausal females were included in the study. Serum levels of osteoprotegerin (OPG) and RANKL were measured using ELISA kits. Body composition and bone mineral density (BMD) were assessed using dual-energy X-ray absorptiometry. Complex-based chemical shift imaging-based MRI was employed to evaluate the vertebral marrow proton density fat fraction (PDFF). A multivariate linear regression model was utilized to analyze the predictive effects of PDFF and BMD on circulating levels of OPG and RANKL.

Results

Simple regression analysis showed significant associations among the marrow PDFF, BMD at either site, serum RANKL, and the RANKL/OPG ratio. In multivariate linear regression models, marrow PDFF was found to have a positive correlation (β = 3.15, 95% CI 2.60 to 3.70) and BMD had negative correlations (β = -0.200, 95% CI -0.348 to -0.051 for vertebral BMD; β = -0.383, 95% CI -0.589 to -0.177 for total hip BMD; and β =-0.393, 95% CI -0.598 to -0.188 for femoral neck BMD, all p < 0.01) with circulating soluble RANKL levels after adjusting for age, body mass index, physical activity, total fat mass, android/gynoid ratio, and lean mass. Similar results were observed for the RANKL/OPG ratio. Additionally, multivariate linear regression analyses revealed that marrow PDFF was a significant independent contributor of circulating soluble RANKL (β = 1.34, 95% CI 1.10 to 1.58, p < 0.001) after further controlling for BMD. However, marrow PDFF or BMD had no associations with circulating levels of OPG after adjusting for all potential confounders mentioned above.

Conclusions

Vertebral marrow fat fraction is independently associated with circulating soluble RANKL levels in postmenopausal females.

Association of serum Spp1 levels with disease progression in ALS and SBMA

OBJECTIVE

In comparison with amyotrophic lateral sclerosis (ALS), the contribution of neuroinflammation in spinobulbar muscular atrophy (SBMA) has been less explored. We investigated the role of neuroinflammation in the pathogenesis of ALS and SBMA by analyzing systemic inflammatory markers and osteopontin (Spp1).

METHODS

This study involved 105 ALS, 77 SBMA, and 55 healthy controls. We measured their systemic inflammatory markers, serum Spp1, and cytokine levels (interferon-γ, interleukin [IL]-1β, IL-6, IL-8, IL-10, tumor necrosis factor-α, and IL-17A), investigated correlations between Spp1 levels and clinical features, and evaluated ALS survival rates according to Spp1 levels.

RESULTS

In the ALS group, systemic inflammatory markers were significantly higher than in the control and SBMA groups. Spp1 levels were observed to be higher in ALS patients, but the difference was not statistically significant among the study groups. Cytokine profiles were comparable. In ALS, higher Spp1 levels were correlated with lower ALS Functional Rating Scale-Revised (ALSFRS-R) scores (r = -0.25, p = 0.02) and faster disease progression rate (r = 0.37, p < 0.001). After adjusting for other prognostic indicators, high Spp1 levels were independently associated with shorter survival in ALS patients (hazard ratio 13.65, 95% confidence interval 2.57-72.53, p < 0.01).

INTERPRETATION

Neuroinflammation does not appear to be a primary contributor to the pathogenesis of SBMA. Serum Spp1 levels may serve as a reliable biomarker for disease progression and prognosis in ALS. These findings expand our understanding of these two distinct motor neuron disorders and offer a potential biomarker for future studies.

Osteoprotegerin in infection-induced acute inflammatory states in children

Background and aims

Osteoprotegerin (OPG) is a tumor necrosis factor receptor superfamily member which increases in chronic inflammation and is associated with altered bone turnover and cardiovascular complications. In this study, we investigated whether OPG increases during acute inflammatory states induced by infections in children and correlated its levels with other biomarkers.

Materials and methods

This is a prospective study that included 59 patients with documented bacterial infections, 20 with viral infections and 20 healthy controls. OPG, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and white blood cells (WBC) were measured.

Results

OPG serum levels were significantly increased during inflammation induced by a bacterial infection, compared to viral infection and controls (4.17 pmol/l (2.40-12.12) vs 3.2 (1.66-5.33) and 3 pmol/l (2.13-4.76), respectively, p < 0.001). In addition, OPG correlated well with CRP (rho = 0.428, p = 0.0011), ESR (rho = 0.3, p = 0.026), and WBC (rho = 0.266, p = 0.05) only in the group with bacterial infection. The sensitivity of CRP in detecting a bacterial infection was superior to OPG (67.3% vs 38.3%).

Conclusion

This study provides proof of concept that OPG increases differentially in bacterial infections, although with a lower sensitivity than CRP. Further studies are needed to define the role of OPG during the inflammatory states of infection in pediatric infections.

Correlates of Circulating Osteoprotegerin in Women with a Pathogenic or Likely Pathogenic Variant in the BRCA1 Gene

BACKGROUND

Lower levels of osteoprotegerin (OPG), the decoy receptor for receptor activator of NFκB (RANK)-ligand, have been reported among women with a BRCA1 mutation, suggesting OPG may be marker of cancer risk. Whether various reproductive, hormonal, or lifestyle factors impact OPG levels in these women is unknown.

METHODS

BRCA1 mutation carriers enrolled in a longitudinal study, no history of cancer, and a serum sample for OPG quantification, were included. Exposure information was collected through self-reported questionnaire at study enrollment and every 2 years thereafter. Serum OPG levels (pg/mL) were measured using an ELISA, and generalized linear models were used to assess the associations between reproductive, hormonal, and lifestyle exposures at the time of blood collection with serum OPG. Adjusted means were estimated using the fully adjusted model.

RESULTS

A total of 701 women with a median age at blood collection of 39.0 years (18.0-82.0) were included. Older age (Spearman r = 0.24; P < 0.001) and current versus never smoking (98.82 vs. 86.24 pg/mL; Pcat < 0.001) were associated with significantly higher OPG, whereas ever versus never coffee consumption was associated with significantly lower OPG (85.92 vs. 94.05 pg/mL; Pcat = 0.03). There were no other significant associations for other exposures (P ≥ 0.06). The evaluated factors accounted for 7.5% of the variability in OPG.

CONCLUSIONS

OPG is minimally influenced by hormonal and lifestyle factors among BRCA1 mutation carriers.

IMPACT

These findings suggest that circulating OPG levels are not impacted by non-genetic factors in high-risk women.

Effect of emicizumab prophylaxis on bone and joint health markers in people with haemophilia A without factor VIII inhibitors in the HAVEN 3 study

INTRODUCTION

Emicizumab prophylaxis significantly reduces bleeding events; however, the associated impact on bone/joint health is unknown.

AIM

To explore the effect of emicizumab prophylaxis on bone/joint health in people with haemophilia A (PwHA) without FVIII inhibitors enrolled in HAVEN 3 (NCT02847637).

METHODS

Haemophilia joint health scores (HJHS; v2.1) were evaluated at baseline and Weeks 49 and 97 in PwHA receiving emicizumab (n = 134), and at baseline and Weeks 49, 73 and 97 in PwHA who switched to emicizumab after 24 weeks of no prophylaxis (n = 17). Bone and joint biomarkers were measured in 117 PwHA at baseline and at Weeks 13, 25, 49 and 73.

RESULTS

HJHS was lower for PwHA who were previously on FVIII prophylaxis, aged <40 years or had no target joints at baseline compared with PwHA who were receiving no prophylaxis, aged ≥40 years or with target joints. Clinically significant mean (95% confidence interval) improvements from baseline of -2.13 (-3.96, -.29) in HJHS joint-specific domains were observed at Week 49 in PwHA with at least one target joint at study entry (n = 71); these changes were maintained through Week 97. Improvements in HJHS from baseline were also observed for PwHA aged 12-39 years. Biomarkers of bone resorption/formation, cartilage degradation/synthesis, and inflammation did not change significantly during emicizumab prophylaxis.

CONCLUSIONS

Clinically relevant improvements in HJHS were observed in younger PwHA and those with target joints after 48 weeks of emicizumab in HAVEN 3. Biomarkers of bone/joint health did not show significant changes during 72 weeks of emicizumab prophylaxis.

Associations of Bone Mineral Density with RANKL and Osteoprotegerin in Arab Postmenopausal Women: A Cross-Sectional Study

Background and objective: There is limited information as to the association of several key bone markers with bone mineral density (BMD) in understudied ethnic groups. This study investigated the relationship between circulating levels of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-Β ligand (RANKL) with BMD in Arab postmenopausal women. Materials and methods: In this cross-sectional study, a total of 617 Saudi postmenopausal women from the Osteoporosis Registry of the Chair for Biomarkers of Chronic Diseases were included. Anthropometric data, BMD, and biochemical data were retrieved from the registry. Participants were stratified into three groups based on T-score; n = 169 with osteoporosis, n = 282 with osteopenia, and n = 166 normal. Analysis of bone markers including RANKL, OPG, osteocalcin, and N-terminal telopeptide (NTx) was completed using commercially available bioassays. Results: The results suggested that OPG was significantly and positively correlated with age in the osteoporosis group (r = 0.29, p < 0.05), while it was inversely correlated with BMD femoral neck left (r = −0.56, p < 0.001) and BMD femoral neck right (r = −0.37, p < 0.05) in the same group. Moreover, RANKL showed a significant inverse correlation with NTx in the osteopenia group (r = −0.37, p < 0.05). Furthermore, the RANKL/OPG ratio had a positive and significant correlation with BMI (r = 0.34, p < 0.05), BMD femoral neck left (r = 0.36, p < 0.05) and BMD femoral neck right (r = 0.35, p < 0.05) in the osteopenia group. By contrast, it showed a significant inverse correlation with waist to hip ratio in the osteoporosis group (r = −0.38, p < 0.05). Multiple regression analysis showed that OPG contributes to BMD variations in the osteopenia group (p = 0.03). Conclusions: In conclusion, changes in circulating levels of RANKL and OPG might be a protective mechanism contrary to the increased bone loss in postmenopausal women.

Delineating the role of osteoprotegerin as a marker of breast cancer risk among women with a BRCA1 mutation

Women with a pathogenic germline mutation in the BRCA1 gene face a very high lifetime risk of developing breast cancer, estimated at 72% by age 80. Prophylactic bilateral mastectomy is the only effective way to lower their risk; however, most women with a mutation opt for intensive screening with annual MRI and mammography. Given that the BRCA1 gene was identified over 20 years ago, there is a need to identify a novel non-surgical approach to hereditary breast cancer prevention. Here, we provide a review of the emerging preclinical and epidemiologic evidence implicating the dysregulation of progesterone-mediated receptor activator of nuclear factor κB (RANK) signaling in the pathogenesis of BRCA1-associated breast cancer. Experimental studies have demonstrated that RANK inhibition suppresses Brca1-mammary tumorigenesis, suggesting a potential target for prevention. Data from studies conducted among women with a BRCA1 mutation further support this pathway in BRCA1-associated breast cancer development. Progesterone-containing (but not estrogen-alone) hormone replacement therapy is associated with an increased risk of breast cancer in women with a BRCA1 mutation. Furthermore, BRCA1 mutation carriers have significantly lower levels of circulating osteoprotegerin (OPG), the decoy receptor for RANK-ligand (RANKL) and thus endogenous inhibitor of RANK signaling. OPG levels may be associated with the risk of disease, suggesting a role of this protein as a potential biomarker of breast cancer risk. This may improve upon current risk prediction models, stratifying women at the highest risk of developing the disease, and further identify those who may be targets for anti-RANKL chemoprevention. Collectively, the evidence supports therapeutic inhibition of the RANK pathway for the primary prevention of BRCA1-associated breast cancer, which may generate unique prevention strategies (without prophylactic surgery) and enhance quality of life.

Menopausal Transition: Prospective Study of Estrogen Status, Circulating MicroRNAs, and Biomarkers of Bone Metabolism

OBJECTIVE

Osteoporosis is associated with an impaired balance between bone resorption and formation, which in turn leads to bone loss and fractures. Many recent studies have underlined the regulatory role of microRNAs (miRNAs) in bone remodeling processes and their potential as biomarkers of osteoporosis. The purpose of this study was to prospectively examine the association of circulating miRNAs and bone biomarkers with estrogen status in women before and after oophorectomy, as well as in oophorectomized women on estrogen therapy.

METHODS

In this prospective study, we included 11 women before oophorectomy and hysterectomy and at 201 ± 24 days after the surgery. Another 11 women were evaluated 508 ± 127 days after oophorectomy and hysterectomy and after an additional 203 ± 71 days of estradiol treatment. Serum miRNAs were profiled by sequencing. Estrogen status and biomarkers of bone metabolism were quantified. Bone mineral density was assessed in the lumbar spine.

RESULTS

Our analysis revealed 17 miRNAs associated with estrogen levels. Of those miRNAs that were upregulated with estrogen deficiency and downregulated after estrogen therapy, miR-422a correlated with serum beta-carboxy-terminal type I collagen crosslinks (β-CTX) and procollagen 1 N-terminal propeptide (P1NP); and miR-1278 correlated with serum β-CTX, P1NP, osteocalcin, sclerostin, and Dickkopf-1(Dkk1). In contrast, we found an inverse association of miR-24-1-5p with estrogen status and a negative correlation with serum β-CTX, P1NP, osteoprotegerin, and sclerostin levels.

CONCLUSION

The reported miRNAs associated with estrogen status and bone metabolism could be potential biomarkers of bone pathophysiology and would facilitate studies on the prevention of postmenopausal osteoporosis. Our findings require validation in an extended cohort.

Physical activity and Mediterranean diet as potential modulators of osteoprotegerin and soluble RANKL in gBRCA1/2 mutation carriers: results of the lifestyle intervention pilot study LIBRE-1

Purpose

Emerging evidence suggests that the progesterone-mediated receptor activator of nuclear factor κB (RANK)/soluble RANK ligand (sRANKL)/osteoprotegerin (OPG) pathway plays an important role in mammary carcinogenesis and is hyperactivated in germline (g)BRCA1/2 mutation carriers. We analyzed the effects of a 3-month intensive lifestyle intervention within the LIBRE-1 study on the serum levels of OPG and sRANKL and hypothesized that the intervention program provides a beneficial impact on the biomarkers by increasing OPG and reducing sRANKL serum concentrations.

Methods

Serum levels of OPG and sRANKL of 49 gBRCA1/2 mutation carriers were quantified using enzyme-linked immunosorbent assays. We used previously collected blood samples from participants of the prospective LIBRE-1 study, who were randomized into an intervention group (IG), increasing physical activity and adherence to the Mediterranean diet (MedD) through supervised sessions from study entry to the first study visit after 3 months and a usual-care control group (CG). Differences in biomarker levels before and after the 3-month intervention were tested within and between study groups.

Results

The lifestyle intervention resulted in a significant increase in OPG for participants in both the IG (q = 0.022) and CG (q = 0.002). sRANKL decreased significantly in the IG (q = 0.0464) and seemed to decrease in the CG (q = 0.5584). An increase in the intake of Omega-3 polyunsaturated fatty acids was significantly associated with an increase in OPG (r = 0.579, q = 0.045). Baseline serum levels of sRANKL were a strong predictor for the change of sRANKL in the course of the intervention (ß-estimate = − 0.70; q = 0.0018). Baseline physical fitness (assessed as VO₂peak) might predict the change of OPG in the course of the intervention program (ß-estimate = 0.133 pg/ml/ml/min/kg; p = 0.0319; q = 0.2871).

Conclusion

Findings from this pilot study seem to confirm our hypothesis by showing an increase in OPG and decrease in sRANKL over a 3-month lifestyle intervention and suggest that increased physical activity and adherence to the MedD are potent modulators of the biomarkers OPG and potentially sRANKL.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10549-021-06400-7.

Association between Osteoprotegerin and Charcot Neuroarthropathy: a systematic review

AIMS

Osteoprotegerin (OPG) has been associated with Charcot Neuroarthropathy (CN); however, three studied OPG polymorphisms (1181C > G, 245A > C and 950 T > C) have yielded conflicting results. Therefore, this meta-analysis was conducted to determine the difference in serum OPG concentrations between healthy controls and diabetics with and without CN and the effect OPG polymorphisms have on CN development.

METHODS

PubMed, LILAC, SCOPUS, and EBSCO databases and retrieved publications' bibliographies were searched for studies that examined for OPG and CN. Depending on the heterogeneity, fixed or random effects were used to calculate the pooled odds ratio (OR) or standard difference in means (SDM) with 95% confidence intervals (95%CI) for 5 genetic models (heterozygous, homozygous, dominant, recessive, and allelic) and serum concentrations, respectively.

RESULTS

Seven publications (12 studies) demonstrated that serum OPG concentrations were more elevated in subjects with CN (SDM = 0.719, 95%CI = 0.555-0.883, p < 0.001). When CN was compared to healthy controls or diabetics, the difference was more prominent for healthy controls (SDM = 1.043, 95%CI = 0.676-1.409, p < 0.001) than diabetics (SDM = 0.639, 95%CI = 0.456-0.821, p < 0.001) and the SDM difference was significant (p = 0.013). Using 6 publications (9 studies), neither the 1181C > G or the 950 T > C polymorphisms showed any significant associations for any genetic model. For the 245A > C polymorphism, only the homozygous genetic model showed a significant association between the polymorphism and CN (OR = 2.850, 95%CI: 1.051-7.729, p = 0.040).

CONCLUSIONS

Here, we determined a potential correlation between the CN and serum OPG concentrations and that only the CC genotype of the 245A > C polymorphism showed an increased risk of developing CN.

Association between serum osteoprotegerin level and mortality in kidney transplant recipients - a prospective observational cohort study

Paradoxically, higher serum levels of osteoprotegerin (OPG: a vascular calcification inhibitor) have been associated with increased arterial stiffness, risk of cardiovascular disease and all-cause mortality. A few studies reported that post-transplant OPG levels are associated with mortality in kidney transplant (KT) recipients. In this study, this association was assessed in a cohort of prevalent KT recipients, adjusting for previously untested potential confounders, including fibroblast growth factor 23 (FGF23) and interleukin 6 (IL-6). Socio-demographic and clinical parameters, medical and transplant history, and laboratory data were collected from 982 prevalent KT recipients. The association between serum OPG and all-cause mortality over a 6-year follow-up period was examined using Kaplan-Meier survival curves and multivariable-adjusted Cox regression models. Participants with high serum OPG were more likely female, older, deceased donor KT recipients and have more comorbidity, lower eGFR, higher FGF23, higher IL-6, and longer dialysis vintage. Each 1 pmol/l higher serum OPG level was associated with a 49% higher risk of mortality (hazard ratio (HR) [95% confidence interval (CI)]: 1.49 [1.40-1.61]). This association persisted after adjusting for confounders (HR [95% CI]: 1.20 [1.10-1.30]). In conclusion, serum OPG was associated with all-cause mortality independent of several novel confounders in prevalent KT recipients.

Myostatin and markers of bone metabolism in dermatomyositis

Background

In dermatomyostis (DM) patients, inflammation, reduced activity, and medication have a negative impact on the musculoskeletal system. Several endocrine factors are involved in muscle growth and bone turnover.

Objective: We aimed to investigate factors regulating myogenesis and bone metabolism and to evaluate possible associations between these endocrine factors, muscle strength, and functional tests in DM patients.

Methods

We conducted a cross-sectional study in 20 dermatomyositis patients. Serum levels of myostatin (MSTN), follistatin (FSTN), dickkopf 1 (Dkk1), sclerostin (SOST), periostin (PSTN), the receptor activator nuclear factor kB ligand (RANKL):osteoprotegerin (OPG) ratio and fibroblast growth factor 23 (FGF23) were determined. Physical function was evaluated by hand-held strength measurement, chair rising test, timed up and go test and the 3-min walking test.

Results

Serum MSTN and FGF23 levels (2.5 [1.9; 3.2] vs. 1.9 [1.6; 2.3] and 2.17 [1.45; 3.26] vs. 1.28 [0.79; 1.96], respectively; p <  0.05) were significantly higher in DM patients than in controls. Dkk1 was significantly lower (11.4 [6.9; 20.0] vs. 31.8 [14.3; 50.6], p <  0.01). Muscle strength and physical function tests correlated with each other (e.g. hip flexion – timed up and go test: r = − 0.748, p < 0.01).

Conclusion

In DM patients, biochemical musculo-skeletal markers are altered and physical function shows deficits. All these tests reflect independent of each other different deficits in long-term DM patients which is important for the assessment of DM patients as well as planning of therapeutic interventions in clinical routine.

Circulating bioactive sclerostin levels in an Austrian population-based cohort

Background

Circulating serum sclerostin levels are supposed to give a good estimation of the levels of this negative regulator of bone mass within bone. Most studies evaluating total serum sclerostin found different levels in males compared to females and in older compared to younger subjects. Besides an ELISA detecting total sclerostin an ELISA determining bioactive sclerostin has been developed. The aim of this study was to investigate serum levels of bioactive sclerostin in an Austrian population-based cohort.

Methods

We conducted a cross-sectional observational study in 235 healthy subjects. Using the bioactive ELISA assay (Biomedica) bioactive sclerostin levels were evaluated.

Results

Serum levels of bioactive sclerostin were higher in men than in women (24%). The levels correlated positively with age (r = 0.47). A positive correlation could also be detected with body mass index and bone mineral density.

Conclusion

Using the ELISA detecting bioactive sclerostin our results are consistent with data in the literature obtained by different sclerostin assays. The determination of sclerostin concentrations in peripheral blood thus appears to be a robust parameter of bone metabolism.

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

BACKGROUND

Type 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.

METHODS

Serum 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.

RESULTS

Plasma 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.

CONCLUSIONS

Our 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.

Reproductive and Lifestyle Factors and Circulating sRANKL and OPG Concentrations in Women: Results from the EPIC Cohort

BACKGROUND

Except for a documented increase in osteoprotegerin (OPG) concentrations with older age, data on determinants of soluble Receptor Activator of Nuclear Factor κB (sRANKL) and OPG concentrations in women are limited. We evaluated reproductive and lifestyle factors as potential sources of variation in circulating sRANKL and OPG concentrations in pre- and postmenopausal women.

METHODS

This study includes 2,016 controls [n = 1,552 (76%) postmenopausal, n = 757 (38%) using postmenopausal hormone therapy (PMH)] from a breast cancer case-control study nested in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Serum sRANKL was measured using an ELISA and serum OPG using an electrochemiluminescent assay. Generalized linear models were used to evaluate associations between these analytes and reproductive and lifestyle factors.

RESULTS

Older age at blood collection was associated with lower sRANKL concentrations in postmenopausal women (P trend ≤ 0.03) and higher OPG concentrations in all women (P trend ≤ 0.01). Longer duration of oral contraceptive use among premenopausal women and postmenopausal PMH users was associated with higher OPG (P trend ≤ 0.04). In postmenopausal non-PMH users, sRANKL concentrations were lower with longer duration of oral contraceptive use and current (vs. never) smoking (P ≤ 0.01). sRANKL concentrations were higher among women with higher BMI (P trend ≤ 0.01). The evaluated factors accounted for 12% of the variation in sRANKL concentrations and 21% of the variation in OPG concentrations.

CONCLUSIONS

Circulating sRANKL and OPG concentrations are minimally impacted by hormone-related factors in pre- and postmenopausal women.

IMPACT

This study suggests circulating concentrations of sRANKL and OPG are unlikely to be strongly modified by hormone-related reproductive and lifestyle factors.

The impact of nonosteogenic factors on the expression of osteoprotegerin and RANKL during human fracture healing

Objectives

The osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-B ligand (RANKL) balance is of the utmost importance in fracture healing. The aim of this study was therefore to investigate the impact of nonosteogenic factors on OPG and RANKL levels.

Methods

Serum obtained from 51 patients with long bone fractures was collected over 48 weeks. The OPG and serum sRANKL (soluble RANKL) concentrations were measured using enzyme-linked immunosorbent assay (ELISA). Smoking habit, diabetes, and alcohol consumption were recorded.

Results

Age and sex greatly influenced preoperative serum levels of OPG and sRANKL but differences were even more pronounced during fracture healing. Statistical significance was observed for overall serum levels of OPG (p = 0.001) and sRANKL (p < 0.001) in older men and women (age greater than 50 years). Interestingly, OPG levels increased over time in older women but decreased over time in older men.

Conclusion

These data suggest that nonosteogenic factors, most significantly age and sex, have a major impact on sRANKL and OPG levels. Given the established association of OPG and sRANKL levels and nonunion, these findings seem to be of clinical relevance.

Cite this article: J. Starlinger, G. Kaiser, A. Thomas, K. Sarahrudi. The impact of nonosteogenic factors on the expression of osteoprotegerin and RANKL during human fracture healing. Bone Joint Res 2019;8:349–356. DOI: 10.1302/2046-3758.87.BJR-2018-0116.R3.

Myostatin and other musculoskeletal markers in lung transplant recipients

Recipients of lung transplantation (LuTx) may experience impaired muscle function and bone metabolism even after rehabilitation. We investigated the potential use of musculoskeletal markers in identifying the impairment of muscle function and bone function in these patients. Biochemical parameters, bodily functions, and lung function of 37 LuTx recipients were evaluated at the time of their discharge from the hospital stay and about 6 months later. The biomarkers were also assessed in 30 healthy age and gender distribution-matched controls. Compared to controls, the negative muscle regulator myostatin was elevated in LuTx recipients at baseline and follow-up, whereas its opponent follistatin only showed a group-specific difference at follow-up. LuTx recipients had reduced serum levels of sclerostin and increased levels of dickkopf 1 and periostin. Lung function and physical function were improved during follow-up. The change in lung function was correlated with the change in chair-rising time and the 6-min walking test. At follow-up, all musculoskeletal markers of LuTx recipients differed from those of controls, thus reflecting their still reduced lung function and bodily functions. Among the tested biomarkers, myostatin, sclerostin, dickkopf 1, and periostin were useful to detect impaired musculoskeletal function in LuTx recipients. Myostatin may serve as a target of treatment in the future.

RANKL/OPG system regulation by endogenous PTH and PTH1R/ATF4 axis in bone: Implications for bone accrual and strength in growing rats with mild uremia

Osteoprotegerin (OPG), receptor activator of NF-κB ligand (RANKL), and parathyroid hormone (PTH) play a central role in the regulation of bone turnover in chronic kidney disease (CKD), but their influence on bone mineral density (BMD) and strength remains unclear, particularly in children. We studied the clinical significance of OPG and RANKL in relation to PTH, femur weight, BMD, and bone biomechanical properties in growing rats after one month (CKD-1) and three months (CKD-3) of surgically-induced mild CKD. Gene expression of parathyroid hormone 1 receptor (PTH1R) and activating transcription factor 4 (ATF4), major regulators of anabolic PTH response in bone, was also determined. Serum PTH and bone PTH1R/ATF4 expression was elevated in CKD-3 compared with other groups, and it positively correlated with femur weight, BMD, and the biomechanical properties of the femoral diaphysis reflecting cortical bone strength. In contrast, bone RANKL/OPG ratios were decreased in CKD-3 rats compared with other groups, and they were inversely correlated with PTH and the other abovementioned bone parameters. However, the PTH-PTH1R-ATF4 axis exerted an unfavorable effect on the biomechanical properties of the femoral neck. In conclusion, this study showed for the first time an inverse association between serum PTH and the bone RANKL/OPG system in growing rats with mild CKD. A decrease in the RANKL/OPG ratio, associated with PTH-dependent activation of the anabolic PTH1R/ATF4 pathway, seems to be responsible for the unexpected, beneficial effect of PTH on cortical bone accrual and strength. Simultaneously, impaired biomechanical properties of the femoral neck were observed, making this bone site more susceptible to fractures.

Influence of Parathyroidectomy on Bone Metabolism and Bone Pain in Patients with Secondary Hyperparathyroidism

BACKGROUND

After parathyroidectomy (PTX), hungry bone syndrome leads to hypocalcemia due to bone remineralization. The aim of this pilot study was to analyze changes in markers of bone metabolism in patients with secondary hyperparathyroidism (sHPT) after PTX and to correlate these markers with bone pain measured with a validated questionnaire.

MATERIALS AND METHODS

All patients who underwent PTX for sHPT between March 2010 and February 2012 at out institution were included in this prospective observational pilot study. At the day before surgery and on the 3rd day thereafter, levels of parathyroid hormone (PTH), calcium, osteocalcin, alkaline phosphatase (AP), bone-specific AP (BAP), tartrate-resistant acid phosphatase 5b (TRAP5b), osteoprotegerin (OPG), sclerostin, fibroblast growth factor 23, and Klotho were measured. Additionally, all patients were requested to answer the Brief Pain Inventory preoperatively and on the 5th postoperative day.

RESULTS

A total of 35 patients with a mean age of 49.8 years were analyzed. A significant difference between the pre- and postoperative values could be detected in PTH, calcium, BAP, TRAP5b, and sclerostin. The highest correlation of laboratory markers with bone pain was found for preoperative PTH (r = 0.3), postoperative OPG (r = 0.4), postoperative BAP (r = -0.4), and postoperative Klotho (r = -0.4).

CONCLUSIONS

The present study revealed significant perioperative changes in PTH, BAP, sclerostin, and TRAP5b after PTX. These markers may serve as laboratory markers to monitor bone metabolism in patients with sHPT. PTH, OPG, and sclerostin were the parameters with the closest correlation to bone pain. However, larger prospective trials with a longer follow-up are required to confirm these results.

The key role of proinflammatory cytokines, matrix proteins, RANKL/OPG and Wnt/β-catenin in bone healing of hip arthroplasty patients

INTRODUCTION

We still lack understanding of why some implants fail while most remain stable after decades of use. Proinflammatory cytokines, matrix proteins and bone regulating cytokines of the RANKL/OPG (receptor activator of nuclear factor kappa B ligand/osteoprotegerin) and Wnt/β-catenin pathways are mandatory for normal bone repair but their spatial and temporal role in the healing of primary total hip arthroplasties (THA) has not been previously shown.

MATERIALS AND METHODS

Twenty-four osteoarthritis patients with one-sided well-fixed primary THA were prospectively monitored during 18years (18Y) with repeated blood samples, clinical variables and radiographs. Eighty-one healthy donors divided in three age- and gender-matched groups and twenty osteoarthritis patients awaiting THA and serving as control of the validity of stored plasma in THA patients, were included. Plasma was analyzed for C-reactive protein (CRP), interleukin (IL)-6, IL-8, IL-1β, tumor necrosis factor (TNF)-α, osteopontin (OPN), secreted protein acidic and rich in cysteine (SPARC/osteonectin), osteocalcin (OC), bone specific alkaline phosphatase (BALP), N-terminal propeptide of collagen type I (P1NP), RANKL, OPG, the Wnt agonistic ligands (Wnt)-1 and Wnt-3a, and the Wnt antagonists sclerostin, Dickkopf (Dkk)-1, Dkk-3, Dkk-4, secreted frizzled related protein (sFRP)-1, sFRP-3 and Wnt inhibitory factor-1 (Wif-1).

RESULTS

Inflammatory mediators in arthroplasty patients (CRP, IL-6, OPN) increased significantly on day one after surgery vs preoperative value (PR) and healthy subjects and returned to baseline at 6W. TNF-α did not change relative preoperative level or healthy subjects. SPARC and OC increased in a biphasic fashion with the primary phase beginning shortly after surgery and lasting 3M (SPARC) and 2Y (OC) while the secondary phase peaked at 1Y (SPARC) and 13Y (OC), with both returning to basal level at 15Y. BALP peaked at 3M after surgery with a return to basal level at 2Y followed by a continuous increase from 5Y until 18Y. P1NP increased immediately after surgery and returned to basal level at 6W followed by a new peak at 10Y returning to basal at 13Y. IL-8 and IL-1β peaked at 5Y post-THA and returned to basal level at 10Y. RANKL/OPG and Wnt/β-catenin remained at preoperative levels until 5Y post-THA when a sustained increase in OPG level, paralleled by a sustained decrease in sclerostin, started and lasted until 18Y. Despite a strong increase by RANKL at 13Y, the OPG/RANKL-ratio remained high between 5Y and 18Y. Dkk-1 and sFRP-1 remained at basal level until 5Y followed by a peak at 7Y and a return to basal level at 15Y. Similarly, RANKL increased after 5Y, peaked at 13Y and returned to basal levels at 18Y, thus coinciding with Wnt-1. In contrast, Wnt3a, Dkk-3, Dkk-4, sFRP-3 and Wif-1 did not differ from preoperative levels or healthy subjects during the course of the follow-up.

CONCLUSION

The primary peak of proinflammatory cytokines involved in the initiation of bone healing after trauma is in line with previous results. The primary phase of increased matrix proteins, P1NP and BALP paralleled by RANKL, OPG and Wnt/β-catenin remaining at preoperative level until 5Y, support a strong formation of mineralized matrix and to a lesser degree bone during this phase. The secondary proinflammatory peak at 5Y is likely a trigger of coupled bone remodeling and neosynthesis as it is followed by increased levels of the bone anabolic turnover marker, BALP, and mediators of the RANKL/OPG and Wnt/β-catenin pathways. A continuous increase by OPG level and the bone turnover marker, BALP, lasting from 5Y until 18Y and paralleled by a similar decrease in sclerostin level support their being key regulators of bone anabolism, whereas the transient and opposed activities of RANKL, Wnt-1, Dkk-1 and sFRP-1 serve as fine tuning tools during the coupled remodeling phase.

Systemic release of osteoprotegerin during oxaliplatin-containing induction chemotherapy and favorable systemic outcome of sequential radiotherapy in rectal cancer

In colorectal cancer, immune effectors may be determinative for disease outcome. Following curatively intended combined-modality therapy in locally advanced rectal cancer metastatic disease still remains a dominant cause of failure. Here, we investigated whether circulating immune factors might correlate with outcome. An antibody array was applied to assay changes of approximately 500 proteins in serial serum samples collected from patients during oxaliplatin-containing induction chemotherapy and sequential chemoradiotherapy before final pelvic surgery. Array data was analyzed by the Significance Analysis of Microarrays software and indicated significant alterations in serum osteoprotegerin (TNFRSF11B) during the treatment course, which were confirmed by osteoprotegerin measures using a single-parameter immunoassay. Patients experiencing increase in circulating osteoprotegerin during the chemotherapy had significantly better 5-year progression-free survival than those without increase (78% versus 48%; P = 0.009 by log-rank test). Hence, systemic release of this soluble tumor necrosis factor decoy receptor following the induction phase of neoadjuvant therapy was associated with favorable long-term outcome in patients given curatively intended chemoradiotherapy and surgery but with metastatic disease as the main adverse event. This finding suggests that osteoprotegerin may mediate or reflect systemic anti-tumor immunity invoked by combined-modality therapy in locally advanced rectal cancer.

Serum Osteoprotegerin Is a Potential Biomarker of Insulin Resistance in Chinese Postmenopausal Women with Prediabetes and Type 2 Diabetes

The aim of this study is to investigate the circulating OPG levels in postmenopausal women with diabetes and prediabetes and explore the relationships between serum OPG and insulin resistance. A total of 271 unrelated Chinese postmenopausal women were recruited in this study. The subjects were divided into type 2 diabetes mellitus (T2DM) group (n = 93), impaired glucose regulation (IGR) (n = 90), and normal glucose regulation group (NGR) (n = 88), according to different glucose regulation categories. Serum OPG levels were measured by enzyme-linked immunosorbent assay. The serum OPG concentration in NGR group, 151.00 ± 45.72 pg/mL, was significantly lower than that in IGR group (169.28 ± 64.91 pg/mL) (p = 0.031) and T2DM group (183.20 ± 56.53 pg/mL) (p < 0.01), respectively. In multiple linear regression analysis, HOMA-IR, age, 2hPG, AST, ALP, and eGFR were found to be independent predictors of OPG. Increased serum OPG levels (OR = 1.009, p = 0.006) may be a risk factor for insulin resistance. The present study suggests that OPG might be implicated in the pathogenesis of diabetes and is a potential biomarker of insulin resistance in subjects with diabetes and prediabetes.

Association of Serum Osteoprotegerin Levels with Bone Loss in Chronic Kidney Disease: Insights from the KNOW-CKD Study

Osteoprotegerin, a potent osteoclast activation inhibitor, decreases bone resorption and positively affects bone mineral density. This study examined the association between serum osteoprotegerin levels and bone loss in patients with chronic kidney disease, a condition associated with increased risk of mineral and bone disorders. The bone mineral densities of the lumbar spine, total hip, and femur neck were assessed by dual-energy X-ray absorptiometry; serum osteoprotegerin levels were measured at baseline for 1,423 patients enrolled in the prospective KoreaN cohort study for Outcome in patients With Chronic Kidney Disease (KNOW-CKD). Patients aged ≥50 years and with a T-score ≤ -2.5 were diagnosed as having osteoporosis. Multivariable linear regression analysis indicated independent association between serum osteoprotegerin levels and decreased bone mineral density in the lumbar spine (B: -0.489, 95% confidence interval [CI]: -0.883 to -0.095, P = 0.015), and total hip (B: -0.349, 95% CI: -0.672 to -0.027, P = 0.027). However, bone mineral density of the femur neck was not associated with serum osteoprotegerin levels in women. After adjustments, no independent association was found between serum osteoprotegerin levels and bone mineral density in men. In multivariable logistic regression analysis, serum osteoprotegerin levels were associated with increased risk of osteoporosis in women (odds ratio [OR]: 4.72, 95% CI: 1.35 to 16.52, P = 0.015), but not in men (OR: 0.21; 95% CI: 0.04 to 1.31, P = 0.095). To summarize, in female patients with chronic kidney disease, increased serum osteoprotegerin levels were independently associated with decreased bone mineral density in the lumbar spine and total hip, and with increased risk of osteoporosis. Therefore, the measurement of serum osteoprotegerin concentration might be useful as a surrogate marker for determining bone loss in patients with chronic kidney disease, especially for women, although not so much for men.

Association between omentin-1, adiponectin and bone health under consideration of osteoprotegerin as possible mediator

PURPOSE

Several studies implicated a crosstalk between bone and fat in the pathogenesis of osteoporosis. Few studies indicated an association between adiponectin and omentin-1 on the bone remodeling process and bone mineral density, and suggested osteoprotegerin (OPG) as a mediator of this relationship. However, only limited evidence on this relationship is available in humans. Therefore, this study aimed to investigate the association between omentin-1, adiponectin and broadband ultrasound attenuation (BUA) in peri-/premenopausal and postmenopausal women, and to assess the role of OPG as a possible mediator.

METHODS

Data from the German population-based EPIC-Potsdam cohort comprising 637 women were analyzed. Multivariable-adjusted ANCOVA including age, BMI, waist circumference, smoking status, education, physical activity, adiponectin or omentin-1 and hormone use was used to investigate potential relationships between the adipokines and BUA levels. A mediation analysis assessed the mediating effect of OPG on the association of BUA and omentin-1 levels.

RESULTS

Peri-/premenopausal women had higher BUA levels (112.5 ± 10.1 dB/MHz), compared to postmenopausal women (106.3 ± 10.0 dB/MHz). In peri-/premenopausal women neither adiponectin nor omentin-1 was significantly associated with BUA. In postmenopausal women, adiponectin was not associated with BUA, but 10 % increase in the omentin-1 concentration was significantly associated with 0.44 dB/MHz lower BUA levels (p = 0.01). Omentin-1 was positively associated with OPG (p = 0.02); however, OPG was not significantly related to BUA (p = 0.62).

CONCLUSION

Our study provides evidence for an inverse association between circulating omentin-1 and BUA levels in postmenopausal women. However, the present findings do not support a mediating effect of OPG in the adipose tissue-bone pathway.

Curcumin improves regulatory T cells in gut-associated lymphoid tissue of colitis mice

AIM: To explore the probable pathway by which curcumin (Cur) regulates the function of Treg cells by observing the expression of costimulatory molecules of dendritic cells (DCs).

METHODS: Experimental colitis was induced by administering 2, 4, 6-trinitrobenzene sulfonic acid (TNBS)/ethanol solution. Forty male C57BL/6 mice were randomly divided into four groups: normal, TNBS + Cur, TNBS + mesalazine (Mes) and TNBS groups. The mice in the TNBS + Cur and TNBS +Mes groups were treated with Cur and Mes, respectively, while those in the TNBS group were treated with physiological saline for 7 d. After treatment, the curative effect of Cur was evaluated by colonic weight, colonic length, weight index of the colon, and histological observation and score. The levels of CD4⁺CD25+Foxp3⁺ T cells (Treg cells) and costimulatory molecules of DCs were measured by flow cytometry. Also, related cytokines were analyzed by enzyme-linked immunosorbent assay.

RESULTS: Cur alleviated inflammatory injury of the colonic mucosa, decreased colonic weigh and histological score, and restored colonic length. The number of Treg cells was increased, while the secretion of TNF-α, IL-2, IL-6, IL-12 p40, IL-17 and IL-21 and the expression of costimulatory molecules (CD205, CD54 [ICAM-1], TLR4, CD252[OX40 L], CD256 [RANK] and CD254 [RANK L]) of DCs were notably inhibited in colitis mice treated with Cur.

CONCLUSION: Cur potentially modulates activation of DCs to enhance the suppressive functions of Treg cells and promote the recovery of damaged colonic mucosa in inflammatory bowel disease.

Angiotensin II Stimulation of Cardiac Hypertrophy and Functional Decompensation in Osteoprotegerin-Deficient Mice

Circulating and myocardial expressions of receptor activator of nuclear factor-κb ligand and osteoprotegerin are activated in heart failure; however, it remains to be determined their pathophysiological roles on left ventricular structure and function in interaction with renin-angiotensin system. We conducted experiments using 8-week-old osteoprotegerin(-/-) mice and receptor activator of nuclear factor-κb ligand-transgenic mice to assess whether they affect the angiotensin II-induced left ventricular remodeling. Subcutaneous infusion of angiotensin II to osteoprotegerin(-/-) mice progressed the eccentric hypertrophy, resulting in left ventricular systolic dysfunction for 28 days, and this was comparable with wild-type mice, showing concentric hypertrophy, irrespective of equivalent elevation of systolic blood pressure. The structural alteration was associated with reduced interstitial fibrosis, decreased procollagen α1 and syndecan-1 expressions, and the increased number of apoptotic cells in the left ventricle, compared with wild-type mice. In contrast, angiotensin II infusion to the receptor activator of nuclear factor-κb ligand-transgenic mice revealed the concentric hypertrophy with preserved systolic contractile function. Intraperitoneal administration of human recombinant osteoprotegerin, but not subcutaneous injection of anti-receptor activator of nuclear factor-κb ligand antibody, to the angiotensin II-infused osteoprotegerin(-/-) mice for 28 days ameliorated the progression of heart failure without affecting systolic blood pressure. These results underscore the biological activity of osteoprotegerin in preserving myocardial structure and function during the angiotensin II-induced cardiac hypertrophy, independent of receptor activator of nuclear factor-κb ligand activity. In addition, the antiapoptotic and profibrotic actions of osteoprotegerin that emerged from our data might be involved in the mechanisms.

Cardiac hypertrophy is exacerbated in aged mice lacking the osteoprotegerin gene

AIMS

Osteoprotegerin (OPG) may play a role in the progression of cardiac hypertrophy and heart failure. However, its pathophysiological role in changes in cardiac structure and function with ageing remains to be elucidated.

METHODS AND RESULTS

We conducted experiments using 2.5- and 12-month-old OPG(-/-) mice and age-matched wild-type (WT) mice and compared the morphology and function of the left ventricle (LV). Both 2.5- and 12-month-old OPG(-/-) mice showed a higher systolic blood pressure and a greater heart weight/body weight ratio than age-matched WT mice. Twelve-month-old OPG(-/-) mice had a significantly larger LV chamber and reduced wall thickness compared with age-matched WT mice, and contractile function was decreased. The morphological differences were accompanied by an increase in the number of apoptotic cells and activation of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) in the LV of 12-month-old OPG(-/-) mice. Correspondingly, OPG small interfering RNA induced the expressions of TRAIL and cleaved caspase-3 in cultured cardiac myocytes. In addition, these mice revealed a decrease in interstitial fibrosis, activation of matrix metalloproteinase (MMP)-2 and tissue inhibitors of MMP-1 and -2, and inactivation of procollagen α1 synthesis. Moreover, intraperitoneal administration of recombinant OPG to either 2.5- or 12-month-old OPG(-/-) mice for 28 days led to partial improvement of LV structure and function without affecting systolic blood pressure.

CONCLUSION

These results suggest that OPG plays a role in preserving myocardial structure and function with ageing through a reduction in apoptosis and preservation of the matrix structure. In addition, this appears to be independent of effects on the vasculature.

Relationship between osteoprotegerin and mortality in decompensated heart failure with preserved ejection fraction

AIM

The aim of this study was to evaluate whether osteoprotegerin - an emerging inflammatory biomarker in cardiovascular diseases - predicts outcomes in patients with acute heart failure and preserved ejection fraction.

METHODS

We measured urea, creatinine, hemoglobin, high-sensitivity C-reactive protein, N-terminal pro-B-type natriuretic peptide and osteoprotegerin on admission in 177 patients admitted with decompensated heart failure and left ventricular ejection fraction at least 45%. The population was divided according to the median values of osteoprotegerin (158.6 ng/l). Primary and secondary endpoints were all-cause mortality and death/readmission at 1-year follow-up, respectively. Multivariable Cox models were generated for osteoprotegerin and common risk factors. We also evaluated the reclassification of patients into risk categories after adding this biomarker to the model.

RESULTS

A total of 43 patients died during the follow-up and 84 had a combined event. Kaplan-Meier curves showed significantly increased primary and secondary endpoints according to the median of osteoprotegerin (log-rank, P < 0.0001 and 0.001, respectively). After adjustment for age, estimated glomerular filtration rate, hemoglobin, N-terminal pro-B-type natriuretic peptide, BMI and New York Heart Association III-IV, osteoprotegerin was a significant predictor of primary endpoint evaluated as continuous and categorized variable (relative risk 2.49, 95% confidence interval 1.18-5.24, P = 0.016 and relative risk 2.35, 95% confidence interval 1.11-4.96, P = 0.025, respectively). The clinical prediction model with osteoprotegerin evaluated with Net Reclassification Index was not significant.

CONCLUSION

Osteoprotegerin is independently associated with all-cause mortality in patients hospitalized for heart failure with preserved ejection fraction. However, adding this biomarker into a risk model does not improve its prediction value.

Influence of Antenatal Glucocorticosteroid Exposure on Osteoprotegerin and Receptor Activator of Nuclear Factor x03BA;B Ligand Levels in Newborn Infants

BACKGROUND/AIMS

The physiologic relevance of osteoprotegerin (OPG) and the receptor activator of nuclear factor x03BA;B ligand (RANKL) in the preterm neonate is unknown. The aim of this study was to examine the effects of prematurity on OPG and RANKL concentrations at birth and to investigate in particular whether antenatal corticosteroid (ACS) exposure affects serum OPG and RANKL levels in premature neonates.

METHODS

Quantitative determination (enzyme immunoassay) of serum OPG and RANKL at 24 postnatal hours was performed in 47 healthy term neonates, 43 preterm newborns not exposed to ACS, and 55 preterm infants exposed to ACS.

RESULTS

OPG in the ACS-exposed preterm group (median 5.13 pmol/l, range 1.62-15.12) was significantly higher compared to preterm neonates not exposed to ACS (median 4.52 pmol/l, range 0.86-8.98, p < 0.05) and to unexposed term neonates (median 4.47 pmol/l, range 2.70-10.72, p < 0.05). Conversely, there was no difference in RANKL levels between the study groups. OPG and RANKL values were also similar between term and preterm neonates not exposed to ACS.

CONCLUSIONS

Preterm neonates exposed to ACS have higher serum levels of OPG, while premature neonates not exposed to ACS have serum OPG and RANKL levels similar to those measured in healthy term neonates.

Effects of Antitumor Necrosis Factor Therapy on Osteoprotegerin, Neopterin, and sRANKL Concentrations in Patients with Rheumatoid Arthritis

Background. Rheumatoid arthritis is a systemic autoimmune disease characterized by joint erosions, progressive focal bone loss, and chronic inflammation. Methods. 20 female patients with moderate-to-severe rheumatoid arthritis were treated with anti-TNF-antibody adalimumab in addition to concomitant antirheumatic therapies. Patients were assessed for overall disease activity using the DAS28 score, and neopterin, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) concentrations as well as osteoprotegerin (OPG) and soluble receptor activator of NF-κB ligand (sRANKL) concentrations were determined before therapy and at week 12. Neopterin as well as OPG and sRANKL were determined by commercial ELISAs. Results. Before anti-TNF therapy patients presented with high disease activity and elevated concentrations of circulating inflammatory markers. OPG concentrations correlated with neopterin (rs = 0.494, p = 0.027), but not with DAS28. OPG concentrations and disease activity scores declined during anti-TNF-treatment (both p < 0.02). Patients who achieved remission (n = 7) or showed a good response according to EULAR criteria (n = 13) presented with initially higher baseline OPG levels, which subsequently decreased significantly during treatment (p = 0.018 for remission, p = 0.011 for good response). Conclusions. Adalimumab therapy was effective in modifying disease activity and reducing proinflammatory and bone remodelling cascades.

Cystatin C as a potential predictor of osteoprotegerin levels in healthy men, a cross-sectional, observational study

Background

The aim of the present study is to evaluate serum osteoprotegerin (OPG) and soluble receptor activator of nuclear factor κB ligand (sRANKL) levels in a randomly selected male cohort over 50 years of age and its association with cystatin C, a cysteine proteinase inhibitor that decreases formation of osteoclasts by interfering at a late stage of pre-osteoclast differentiation, apart from being a marker of renal function independent of gender, muscle mass and age; in addition to known predictors such as age, sex hormones, vitamin D, bone mineral density (BMD) and biochemical markers of bone turnover.

Methods

We determined serum OPG and sRANKL levels and examined its relationship with cystatin C, age, osteocalcin, C-terminal telopeptides of type-I collagen, procollagen type 1 amino-terminal propeptide, 25-hydroxyvitamin D, parathyroid hormone, total 17β-estradiol (E2), total testosterone and L1–L4 (LS) and femur neck (FN) BMD data available from 194 (age, range: 51–81 years) randomly selected ambulatory men belonging to the HunMen cohort.

Results

OPG correlated significantly with age (Spearman’s rho (r) = 0.359, p < 0.001), cystatin C (r = 0.298, p < 0.001), E2 (r = 0.160, p = 0.028) and free testosterone index (FTI) (r = −0.230, p = 0.001). Compared to the middle-aged (age: ≤ 59 years, n = 98), older men (age > 59 years, n = 96) had significantly higher serum OPG (4.6 pmol/L vs. 5.4 pmol/L; p < 0.001), and lower sRANKL (0.226 pmol/L vs. 0.167 pmol/L; p = 0.048) levels. The older men showed a significant correlation between serum OPG levels and cystatin C (Spearman’s rho = 0.322, p = 0.002), and E2 (Spearman’s rho = 0.211, p = 0.043). Including cystatin C and E2 in a regression model showed that cystatin C (standard regression coefficient (β) = 0.345; p = 0.002) was the only significant predictor of serum OPG levels in the older men.

Conclusions

The results of this study demonstrated that in addition to age (which was the stronger predictor), other modifiable factors such as cystatin C, FTI and E2 were also significant predictors of OPG, and that the association between cystatin C and OPG was more evident with increased age (older age group). As such, cystatin C is a significant predictor of OPG independently of age, FTI and E2.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-015-0684-1) contains supplementary material, which is available to authorized users.

Association of osteoprotegerin and bone loss after adjuvant chemotherapy in early-stage breast cancer

PURPOSE

Chemotherapy induced ovarian failure (CIOF) results in rapid bone loss. Receptor Activator of Nuclear Factor Kappa-B (RANK)-RANK ligand (RANK-L) signaling balances bone resorption and formation. Osteoprotegerin (OPG) acts as a decoy receptor for RANK, interrupting osteoclast activation and bone resorption. This study examined the relationship between OPG and bone loss in women with CIOF.

METHODS

Premenopausal women with stage I/II breast cancers receiving adjuvant chemotherapy were evaluated at chemotherapy initiation, 6 and 12 months. Bone mineral density (BMD) at the lumbar spine (LS) and femoral neck (FN), follicle stimulating hormone (FSH), ionized calcium, osteocalcin, and OPG were serially measured. CIOF was defined as a negative pregnancy test, FSH levels >30 MIU/mL, and ≥3 months of amenorrhea.

RESULTS

Forty women were enrolled; 31 (77.5%) met CIOF criteria. BMD significantly decreased (p < 0.001) in the CIOF group at both time points: LS BMD decreased from a median of 0.993 g/cm(2) to 0.976 g/cm(2) and 0.937 g/cm(2) at 6 and 12 months, respectively. OPG was significantly elevated at 6 months (median increase 0.30 pmol/L, p = 0.015) and then decreased at 12 months to levels still above baseline (median difference 0.2 pmol/L, p = 0.70).

CONCLUSIONS

In what was likely a compensatory response to rapid bone loss, CIOF patients' OPG levels increased at 6 months and then decreased at 12 months to values greater than baseline assessments. This phenomenon is described in other diseases, but never before in CIOF.

Adiponectin exerts its negative effect on bone metabolism via OPG/RANKL pathway: an in vivo study

To explore the effects of adiponectin on the bone metabolism in vivo. Bone mineral density (BMD), bone microstructure, serum adiponectin levels, and biochemical markers of the bone turnover were measured in 12-week-old male Adipo-/- and WT mice. In addition, the osteoclast formation, osteoprotegerin (OPG), and the receptor activator of nuclear factor-κB ligand (RANKL) expression were examined. The serum adiponectin levels were normal in the WT mice while undetectable in the Adipo-/- mice. Compared with the WT mice, the Adipo-/- mice had higher BMD, more trabecular bone, greater bone volume fraction, and trabecular thickness in the left femur. On the contrary, fewer osteoclasts were observed in the Adipo-/- mice when compared with the WT mice. Meanwhile, the Adipo-/- mice had a significantly decreased serum carboxyl-terminal telopeptide of type 1 collagen (CTX)/osteocalcin (OC) ratio. Interestingly, both the adiponectin and RANKL would cause a significant increase of CTX/OC ratio in the co-culture of the CD14+ peripheral blood mononuclear cells and the osteoblasts from Adipo-/- mice. Further, immunohistochemistry assays in tibias and both the RT-PCR and immunoblot analyses in the cultured osteoblasts showed the Adipo-/- mice expressed lower levels of RANKL but higher levels of OPG. Adiponectin had a negative effect on the bone metabolism, and this negative effect might be mediated, at least in part, by the OPG/RANKL pathway.

Osteoprotegerin is not a determinant of metabolic syndrome in sub-Saharan Africans after age adjustment

OBJECTIVES

Osteoprotegerin (OPG), a soluble member of tumor necrosis factor receptor superfamily that inhibits bone resorption, has been suggested as a cardiovascular risk factor in humans. In this study, we aim to investigate the potential relationship between OPG and MetS (MetS) in a sub-Saharan African population.

METHODS

Four hundred and eleven volunteers (152 men, 259 women) aged ≥18 years recruited from the general population in Douala and Edea, Cameroon participated in this study. Anthropometric parameters measured and blood samples were collected for glucose, serum lipids and OPG concentrations measurements. Mean differences of the variables in different groups were compared using Students' t test. We performed logistic regressions to analyze the impact of independent factors on the relation between OPG and MetS outcome. MetS was defined using the Joint Interim Statement 2009.

RESULTS

OPG levels did not vary significantly between both men and women with and without MetS (both P>0.05). However, with high fasting blood glucose (≥5.6 mmol/L) had a significantly higher OPG level than those with lower glucose level (P=0.014). In multiple logistic regression analysis, MetS did not show any significant association with serum OPG levels in men and women after adjusting for age, physical activity, alcohol consumption and menopausal status in women (P=0.720 and P=0.930 respectively).

CONCLUSION

This study failed to demonstrate any relationship between OPG and MetS. Nevertheless, the positive association between blood glucose and OPG levels reveals that OPG might be involved in cardiovascular risk development in this sub-Saharan African population.

Bone biomarkers in patients with chronic traumatic spinal cord injury

BACKGROUND CONTEXT

Bone loss after spinal cord injury (SCI) occurs because of pathologic changes in osteoblastic and osteoclastic activities due to mechanical unloading. Some biochemical changes in bone metabolism after SCI are described before that were related to bone mineral loss.

PURPOSE

Our purpose was to determine bone markers' changes and related effective factors in patients with chronic traumatic SCI.

STUDY DESIGN

This investigation was designed as an observational cross-sectional study.

PATIENT SAMPLE

All patients with chronic SCI who were referred to Brain and Spinal Injury Research Center and did not meet our exclusion criteria entered the study.

OUTCOME MEASURES

Self-reporting measures including patient's demographic features and date of accident were obtained using a questionnaire and physiologic measures including spinal magnetic resonance imaging to determine the level of injury accompanied with physical examination along with dual-energy X-ray absorptiometry were performed. Blood samples were analyzed in the laboratory.

METHODS

Dual-energy X-ray was used to determine bone mineral density in femoral and spinal vertebrae bone sites. Serum level of C-telopeptide cross-linked Type 1 collagen (CTX), parathyroid hormone, calcitonin, osteocalcin, and bone alkaline phosphatase (BALP) were measured.

RESULTS

We detected a negative association between CTX level and bone mineral density in femoral and spinal bone sites that confirms that CTX is a bone resorption marker. C-telopeptide cross-linked Type 1 collagen and BALP levels did not show any significant correlation with postduration injury. Patients with spinal injury at lumbar level had the highest calcitonin level (p<.04). C-telopeptide cross-linked Type 1 collagen was positively related with osteocalcin and BALP (p<.0001, r=0.51), and osteocalcin was positively related with BALP (p<.0001, r=0.44). Osteocalcin was related negatively only to femoral intertrochanteric zone bone mineral density.

CONCLUSIONS

Some bone biomarkers undergo noticeable changes after SCI. C-telopeptide cross-linked Type 1 collagen was positively correlated with BALP and osteocalcin that shows the coincidental occurrence of osteoblastic and osteoclastic activities. Our data also support this fact that although bone reduction after 2 years is slower than acute phase after SCI, bone resorption rate is higher than bone formation. These bone markers also revealed different site of action as osteocalcin level only affected femoral intertrochanteric bone mineral density. Generally, it seems that the coincidental consideration of these factors that influence bone mineral density can lead to a better understanding of bone changes after SCI.

Osteoprotegerin and fractures in men and women with chronic kidney disease

Fractures are common in men and women with chronic kidney disease (CKD) but the best tool to identify those at high risk is unknown. Increased circulating osteoprotegerin(OPG) is associated with fractures in postmenopausal women. We determined if serum OPG was associated with prevalent fractures (self-reported low trauma fractures since 40 years of age and/or prevalent vertebral fractures identified by radiographs) in men (n = 97) and women (n = 67) with stage 3–5 CKD. Analyses were performed unadjusted and adjusted for stage of CKD. Results are expressed as mean ± standard deviation(SD), and as odds ratio (OR) per SD increase in OPG with 95 % confidence intervals (CI). The mean age was 62.7 ± 16.3 years, and mean weight was 78.9 ± 18.7 kg. Compared to those without fractures, those with fractures(n = 55) were older (p < 0.01). Serum OPG increased as kidney function decreased, and OPG was higher in those with fractures compared to those without (9.42 ± 4.08 vs 8.06 ± 3.11 pmol/L, p = 0.02). After adjusting for stage of CKD, increased OPG was associated with an increased fracture risk (OR 1.13, 95 % CI 1.02–1.25); however, OPG did not discriminate fracture status well (area under the receiver operating characteristic curve 0.61, 95 % CI 0.52–0.70). OPG is associated with fractures in men and women with stage 3–5 CKD; however, the ability of OPG to discriminate fracture status is poor and cannot be used in isolation to assess fracture risk. Further studies should examine the ability of OPG in combination with other risk factors to better discriminate fracture status in men and women with CKD.

Lipocalin-type prostaglandin D synthase is not a biomarker of atherosclerotic manifestations

OBJECTIVE

Over the last decades Lipocalin-type prostaglandin D synthase (L-PGDS), Osteoprotegerin (OPG), Osteopontin (OPN) and Pregnancy associated plasma protein A (PAPP-A) have been reported to be associated with coronary artery disease, and L-PGDS has been proposed as a potential new diagnostic tool in the setting of stable coronary artery disease. We set out to investigate if measurement of concentrations of these biomarkers could be used to differentiate between four groups of individuals with different atherosclerotic manifestations.

METHODS

A total of 120 individuals from four equal gender- and age-matched groups were studied: (i) no previous cardiovascular disease (CVD) and no coronary calcifications [CAC-negative group], (ii) no previous CVD but evidence of severe coronary calcifications [CAC-positive group], (iii) acute coronary syndrome [ACS-group], and (iv) clinical stable patients with CVD, who were referred for cardiovascular surgery [CVD-group]. Concentrations of L-PGDS, OPG, OPN and PAPP-A were analyzed and compared between the four groups.

RESULTS

We did not find any significant differences in L-PGDS concentrations between the four groups (p = 0.32). OPG concentrations differed significantly (p = 0.003), with the highest concentration observed in ACS patients. Considering OPN (p = 0.12) and PAPP-A (p = 0.53) their concentrations between groups did not differ significantly.

CONCLUSION

The main message from this study is the observation that L-PGDS based on a single blood test appears to be less valuable than previously proposed in identification of patients with coronary artery disease. However, ACS patients have higher OPG concentrations than patients with different manifestations of stable atherosclerosis. Neither OPN nor PAPP-A concentrations differed between groups.

Osteoprotegerin: a new biomarker for impaired bone metabolism in complex regional pain syndrome?

Osteoprotegerin (OPG) is important for bone remodeling and may contribute to complex regional pain syndrome (CRPS) pathophysiology. We aimed to assess the value of OPG as a biomarker for CRPS and a possible correlation with radiotracer uptake in 3-phase bone scintigraphy (TPBS). OPG levels were analyzed in 23 CRPS patients (17 women; mean age 50±9.0 years; disease duration: 12 weeks [IQR 8-24]), 10 controls (6 women; mean age 58±9.6 years) and 21 patients after uncomplicated fractures (12 women; mean age: 43±15 years; time after fracture: 15 weeks [IQR: 6-22]). The CRPS and control patients also underwent TPBS. OPG in CRPS patients was significantly increased by comparison with both control groups (P=0.001; Kruskal-Wallis test; CRPS patients: 74.1 pg/mL [IQR: 47.1-100.7]; controls: 46.7 pg/mL [IQR: 35.5-55.0]; P=0.004; fracture patients: 45.9 pg/mL [IQR: 37.5-56.7]; P=0.001). As a diagnostic test for CRPS, OPG had a sensitivity of 0.74, specificity of 0.80, positive predictive value of 68% and negative predictive value of 84%. Receiver operating characteristic curve analysis showed an area under the curve of 0.80 (CI: 0.68-0.91). For the CRPS-affected hand, a significant correlation between OPG and TPBS region of interest analysis in phase III was detected (carpal bones; r=0.391; P=0.03). The persistent OPG increase in CRPS indicates enhanced osteoblastic activity shown by increased radiotracer uptake in TPBS phase III. A contribution of bone turnover to CRPS pathophysiology is likely. OPG might be useful as a biomarker for CRPS.

Relation of osteoprotegerin in severe aortic valve stenosis to postoperative outcome and left ventricular function

Osteoprotegerin (OPG) is a member of the tumor necrosis factor receptor superfamily and is known to be among the mediators of the calcification process that has been shown to increase in patients with aortic stenosis (AS). The aim of this study was to characterize the association of OPG with left ventricular (LV) function and remodeling and to evaluate the significance of preoperative OPG on long-term outcome in terms of survival and symptomatic improvement in 124 patients with severe AS scheduled for aortic valve replacement (AVR). Patients were divided according to tertiles of preoperative OPG. Preoperative OPG was associated with age, EuroSCORE, and preoperative functional capacity. Despite similar ejection fraction and diastolic function among groups, longitudinal LV systolic function consistently decreased and markers of filling pressure increased across groups. During median follow-up of 4 years, 41 patients died of a presumed cardiovascular cause or remained in New York Heart Association functional class III or IV. The risk of a poor postoperative outcome after AVR increased with increasing OPG tertiles (15% vs 33% vs 51%, p = 0.002). In a multivariate model containing age, ejection fraction, N-terminal pro-brain natriuretic peptide and left atrial volume index, OPG was still significantly associated with postoperative outcome. In addition, OPG levels associated with cardiovascular mortality during follow-up. In conclusion, OPG is associated with LV and left atrial remodeling in patients with symptomatic severe AS undergoing AVR. Moreover, plasma OPG is associated with long-term postoperative outcome and may identify patients with poor symptomatic improvement after surgery.

Osteoprotegerin contributes to the metastatic potential of cells with a dysfunctional TSC2 tumor-suppressor gene

In addition to its effects on bone metabolism, osteoprotegerin (OPG), a soluble member of the tumor necrosis factor family of receptors, promotes smooth muscle cell proliferation and migration and may act as a survival factor for tumor cells. We hypothesized that these cellular mechanisms of OPG may be involved in the growth and proliferation of lymphangioleiomyomatosis (LAM) cells, abnormal smooth muscle-like cells with mutations in one of the tuberous sclerosis complex tumor-suppressor genes (TSC1/TSC2) that cause LAM, a multisystem disease characterized by cystic lung destruction, lymphatic infiltration, and abdominal tumors. Herein, we show that OPG stimulated proliferation of cells cultured from explanted LAM lungs, and selectively induced migration of LAM cells identified by the loss of heterozygosity for TSC2. Consistent with these observations, cells with TSC2 loss of heterozygosity expressed the OPG receptors, receptor activator of NF-κB ligand, syndecan-1, and syndecan-2. LAM lung nodules showed reactivities to antibodies to tumor necrosis factor-related apoptosis-inducing ligand, receptor activator of NF-κB ligand, syndecan-1, and syndecan-2. LAM lung nodules also produced OPG, as shown by expression of OPG mRNA and colocalization of reactivities to anti-OPG and anti-gp100 (HMB45) antibodies in LAM lung nodules. Serum OPG was significantly higher in LAM patients than in normal volunteers. Based on these data, it appears that OPG may have tumor-promoting roles in the pathogenesis of lymphangioleiomyomatosis, perhaps acting as both autocrine and paracrine factors.

The role of osteoprotegerin in cardiovascular disease

Osteoprotegerin (OPG) is a 401 amino acid N-glycosylated protein, which is highly expressed in a large number of tissues. OPG mainly binds to two ligands, i.e. RANKL (receptor activator of nuclear factor κB ligand) and TRAIL (tumor necrosis factor- related apoptosis-inducing ligand). Upon binding to the former ligand, OPG inhibits the activation of osteoclasts and promotes apoptosis of osteoclasts, whereas the binding of OPG with TRAIL prevents apoptosis of tumor cells. There is now emerging evidence that OPG participates in the pathogenesis of atherosclerosis and cardiovascular diseases by amplifying the adverse effects of inflammation and several traditional risk factors such as hyperlipidemia, endothelial dysfunction, diabetes mellitus, and hypertension. Some epidemiological studies also showed a positive association between OPG levels and cardiovascular morbidity and mortality. The aim of this article is to provide an overview of the main biochemical, physiological, and pathological aspects of OPG biology in cardiovascular disease.

Relationship between Serum Levels of OPG and TGF- β with Decreasing Rate of BMD in Native Chinese Women

The objective of this study was to investigate the relationship between serum levels of OPG, TGF- β 1, and TGF- β 2 and BMD decrease rate (BDR) in native Chinese women. This cross-sectional study was performed on 465 healthy native Chinese women aged 35-80 years. Serum levels of OPG, TGF- β 1, and TGF- β 2 were determined. BDR was measured by DXA at the posteroanterior spine, hip, and distal forearm. At all skeletal sites tested, there was a negative correlation between BDR and serum levels of both OPG (r = -0.122 to -0.230, all P = 0.007-0.000) and TGF- β 2 (r = -0.100 to -0.173, all P = 0.029-0.000) and a positive correlation between BDR and serum TGF- β 1 (r = 0.245 - 0.365, all P = 0.000). After adjustment for age and BMI, there were no statistically significant correlations between serum levels of OPG or TGF- β 2 and BDR. However, statistically significant correlations between serum TGF- β 1 and BDR at the lumbar spine and ultradistal forearm remained. Multiple linear regression stepwise analysis showed that serum OPG could explain 1.4-3.7% of BDR variation. Serum TGF- β 1 was a positive determinant of BDR and could explain 5.3-13.3% of BDR variation.

The effect of exercise on osteoprotegerin and TNF-related apoptosis-inducing ligand in obese patients

BACKGROUND

Biomarkers of cardiovascular (CV) risk are tests that predict a patient's risk of future CV events. Recently, two proteins involved in vascular calcification; serum levels of osteoprotegerin (OPG) and tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) have emerged as potentially useful biomarkers. OPG levels are positively correlated with CV risk, whereas TRAIL levels show a negative correlation. Exercise training is known to reduce risk factors for CV disease by improving metabolism, vascular biology and blood flow. This study examined the effects of a 6-month exercise training programme on levels of OPG and TRAIL. Pulse wave velocity (PWV) and high-sensitivity C-reactive protein (hsCRP) were measured for comparative purposes.

MATERIALS AND METHODS

Overweight and obese patients undertook a 6-month exercise programme. Patients participated in 4 h of primarily aerobic exercise per week of which 2 h were supervised. At the beginning and end of the programme, anthropometric measurements, PWV and serum levels of OPG, TRAIL and hsCRP were measured.

RESULTS

A total of 21 patients (17 men) aged 55.2 ± 10 years completed the programme. Mean body mass index decreased from 34.1 ± 5.8 to 32.6 ± 5.4 kg/m(2) (P<0.05), while waist circumference decreased from 111.8 ± 12.4 to 109.6 ± 12.8 cm (P<0.05). PWV decreased from 9.2 to 8.5 m/s (P<0.02). OPG, TRAIL and hsCRP levels did not change significantly.

CONCLUSIONS

Exercise training reduced PWV but not OPG, TRAIL or hsCRP in this population. These data suggest that while an intervention of this nature improves vascular tone, it does not exert significant effects on serum biomarkers related to atherosclerotic inflammation and calcification.

Effects of 17β-estradiol on adiponectin regulation of the expression of osteoprotegerin and receptor activator of nuclear factor-κB ligand

Adiponectin may exert a negative effect on bone metabolism by regulating osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) expression. However, the action of adiponectin on bone may be influenced by estrogen in women. The present study was undertaken to investigate the effects of 17β-estradiol (E2) on adiponectin-regulated OPG and RANKL expression in human osteoblast. Human osteoblasts were treated with α-MEM containing 10μg/ml adiponectin alone or together with 10(-10) to 10(-8)M E2 for 12-48h. Cells were also treated with α-MEM containing 10μg/ml adiponectin together with 10(-8)M E2 plus p38 agonist-anisomycin or estrogen receptor (ER) antagonist ICI182780 for 48h. The effects of E2 were also investigated by knockdown of ERs or overexpression of p38 MAPK in osteoblasts. Further, we examined the effects of E2 on adiponectin-dependent osteoclastogenesis by the co-culture systems of osteoblast and CD14+ peripheral blood monocytes (PBMCs). Real-time quantitative PCR (RT-PCR) and ELISA were used to detect OPG/RANKL mRNA and their corresponding protein expression, Western Blot was used to analyze the phosphorylated p38 (p-p38) levels. The results showed that E2 blocked adiponectin-induced p38 phosphorylation, decreased adiponectin-regulated OPG/RANKL mRNA and protein expression in a dose- and time-dependent manner. ICI182780 or knockdown of ERs abolished the effects of E2 on adiponectin-dependent p38 phosphorylation and OPG/RANKL expression. Furthermore, anisomycin or overexpression of p38 also reserved the effects of E2 on adiponectin-dependent p38 phosphorylation and OPG/RANKL expression. E2 inhibited adiponectin-dependent osteoclastogenesis in the co-culture systems of osteoblast and CD14+ PBMCs, whereas anisomycin, ICI182780, knockdown of ERs and overexpression of p38 significantly reversed this response. In conclusions, our findings demonstrated, through blocking the activation of adiponectin-induced p38 MAPK, E2 suppressed the adiponectin-regulated OPG/RANKL expression and then inhibited osteoclastogenesis, which suggested that estrogen would suppress the effect of adiponectin on bone metabolism.

[Osteoporosis in men receiving androgen deprivation therapy for non-metastatic prostate cancer]

Osteoporosis is defined as a continuous loss of bone mineral density accompanied by an increased fracture risk in females and males. A fall of estrogen concentrations at the menopause and the consecutive rapid bone loss are an established pathogenic mechanism in female osteoporosis. Males do not have a menopause equivalent during which significant amounts of bone are lost. Several diseases, therapeutic strategies and nutritional deficiencies may also result in bone loss and reduced bone mineral density. Prostate cancer is the most common visceral malignancy in men. Suppression of endogenous androgen production as a therapeutic tool is commonly used in patients with non-metastatic prostate cancer and is associated with significant bone loss and an increased fracture risk. Androgen deprivation therapy is prescribed both for men with locally advanced or high-risk non-metastatic prostate cancer. Osteoclast inhibition with any of several bisphosphonates improves bone mineral density and reduces fracture risk. Denosumab (a monoclonal antibody against RANK ligand) and toremifene (a selective estrogen receptor modulator) recently have been shown to be effective to reduce vertebral fractures in patients with non-metastatic prostate cancer receiving androgen-deprivation therapy. This overview focuses on cancer-treatment-induced bone loss in patients with non-metastatic prostate cancer.

Osteoprotegerin as a marker of atherosclerosis: a systematic update

OBJECTIVE

Osteoprotegerin (OPG) may be involved in development of atherosclerosis. To evaluate plasma concentrations of OPG in individuals with stable coronary artery disease (CAD), acute coronary syndrome (ACS), peripheral artery disease (PAD), and cerebrovascular disease (CBVD) a systematic literature review was performed.

DESIGN AND METHODS

Studies investigating OPG concentrations in stable CAD, ACS, PAD, and CBVD were extracted from PubMed and the Cochrane Library, retrieving 280 articles. Nonrelevant articles were excluded and after thorough evaluation, and only 14 studies with clearly defined cohorts qualified for this review.

RESULTS

In 11 studies, OPG concentrations were elevated. Severity of atherosclerosis was significantly associated with higher OPG concentrations compared to healthy controls. No association between PAD and OPG concentrations was observed.

CONCLUSION

OPG concentrations are associated with the presence and severity of stable CAD, ACS, and CBVD. Larger studies are needed to reach conclusions concerning OPG concentrations in PAD. Studies addressing a putative role for OPG in suspected CAD and CBVD are warranted.