The Utility of Biomarkers in Osteoporosis Management

Effect of Allele-Specific Clcn7G213R siRNA Delivered Via a Novel Nanocarrier on Bone Phenotypes in ADO2 Mice on 129S Background

Autosomal dominant osteopetrosis type 2 (ADO2) is a rare inherited bone disorder characterised by dense but brittle bones. It displays striking phenotypic variability, with the most severe symptoms, including blindness and bone marrow failure. Disease management largely relies on symptomatic treatment since there is no safe and effective treatment. Most ADO2 cases are caused by heterozygous loss-of-function mutations in the CLCN7 gene, which encodes an essential Cl-/H+ antiporter for proper bone resorption by osteoclasts. Thus, siRNA-mediated silencing of the mutant allele is a promising therapeutic approach, but targeting bone for first-in-human translation remains challenging. Here, we demonstrate the utility of silicon-stabilised hybrid lipid nanoparticles (sshLNPs) as a next-generation nucleic acid nanocarrier capable of delivering allele-specific siRNA to bone. Using a Clcn7G213R knock-in mouse model recapitulating one of the most common human ADO2 mutations and based on the 129S genetic background (which produces the most severe disease phenotype amongst current models), we show substantial knockdown of the mutant allele in femur when siRNA targeting the pathogenic variant is delivered by sshLNPs. We observed lower areal bone mineral density in femur and reduced trabecular thickness in femur and tibia, when siRNA-loaded sshLNPs were administered subcutaneously (representing the most relevant administration route for clinical adoption and patient adherence). Importantly, sshLNPs have improved stability over conventional LNPs and enable 'post hoc loading' for point-of-care formulation. The treatment was well tolerated, suggesting that sshLNP-enabled gene therapy might allow successful clinical translation of essential new treatments for ADO2 and potentially other rare genetic bone diseases.

Albumin-to-alkaline phosphatase ratio may be a better predictor of survival than sclerostin, dickkopf-1, osteopontin, osteoprotegerin and osteocalcin

Objectives

The value of biochemical markers of bone turnover (BTMs) in predicting survival and disease remains unclear. In a prospective study we evaluated the novel biomarkers for bone turnover sclerostin, dickkopf-1 (DKK-1), osteopontin (OPN), osteoprotegerin (OPG) and osteocalcin (OC), as well as a traditional biomarker, alkaline phosphatase (ALP) in relation to risk of mortality, cardiovascular events and fractures.

Participants

and Methods:Routine blood tests and serum BTMs, including ALP, were analyzed in patients with hip fracture n = 97, stroke n = 71 and healthy volunteers n = 83 (mean age 86, 83 and 77, respectively), followed for 7 years. Hazard Ratios (HR) were calculated for mortality, cardiovascular events and fractures in relation to these biomarkers. After adding the albumin-to-ALP ratio (AAPR) a post hoc analysis was performed.

Results

120 participants died during the study. In the entire group of patients and volunteers (n = 251) higher AAPR (HR 0.28, 95 % CI 0.14-0.59, p < 0.001) was associated with decreased mortality. OPN and OPG were associated with mortality risk only in the univariate statistical analysis. HR for high AAPR in relation to new cardiovascular events was borderline significant (HR 0.29, 95 % CI 0.08-1.06, p = 0.061). None of the examined biomarkers were associated with new fractures, nor with an increased risk of a new cardiovascular event.

Conclusions

AAPR may be a better predictor of mortality than the more novel BTMs, and higher AAPR could be associated with longer life expectancy. Further studies should determine the clinical usefulness of AAPR as a biomarker of mortality and cardiovascular disease.

Clinical use of bone markers: a challenge to variability

Bone markers are a group of substances released into circulation during bone formation and/or resorption. These substances can be measured in blood and urine to obtain information about metabolic bone disorders. This review provides an insight into factors influencing bone marker variability and describes different approaches to minimize variability and interpret results appropriately. Variability in bone marker concentrations results from biological and analytical variability across assays. Other influencing factors include gender, age, physical exercise, circadian rhythm, and diet. The multiplicity of influencing factors hinders the establishment of accurate reference values. Gaining a deep understanding of bone marker variability is the first step to ascertain their clinical usefulness. Bone marker variability can be minimized by controlling as many variables as it is possible and through the standardization of patient preparation and sample collection and handling.

Utilidad clínica de los biomarcadores óseos: un desafío a la variabilidad

Los biomarcadores óseos son un conjunto de sustancias que son liberadas a la circulación sanguínea durante el proceso de formación y/o resorción ósea y que podemos medir en sangre y orina para obtener información sobre los trastornos metabólicos del hueso. La revisión traza una perspectiva sobre los factores que influyen en la variabilidad de los biomarcadores óseos y describe los aspectos a considerar para reducirla al máximo e interpretar los resultados de manera adecuada. La variabilidad que podemos observar en la concentración de los biomarcadores óseos engloba diversos aspectos que abarcan desde su variabilidad biológica y la variabilidad de los ensayos empleados en su medida hasta la variabilidad derivada de la influencia de numerosos factores, entre los cuales el sexo, la edad, el ejercicio, su ritmo circadiano o la dieta. Todo ello se refleja en la dificultad de establecer valores de referencia precisos. El conocimiento de esta variabilidad es el primer desafío que debe afrontar su empleo en la práctica clínica. Es necesario minimizar la variabilidad de los biomarcadores óseos controlando el máximo de variables que sea posible, así como estandarizando la preparación del paciente antes de la toma de las muestras, así como su obtención y manejo.

Serum Periostin Levels are Significantly Higher in Patients with Primary Hyperparathyroidism and Closely Related to Osteoporosis

BACKGROUND

Periostin is an emerging biomarker that plays a role in bone metabolism and may be associated with bone mineral density (BMD). This study is aimed to investigate serum periostin levels in patients with primary hyperparathyroidism (PHPT) and its correlation with BMD in these patients.

METHODS

Forty patients with newly diagnosed PHPT without co-morbidities and 30 healthy controls were included. Laboratory tests for the diagnosis of PHPT and serum levels of periostin were measured for all patients. BMD was measured on lumbar spines L1 and L4 by dual-energy X-ray absorptiometry (DEXA). Serum periostin levels were detected using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Serum periostin levels were significantly higher in patients with PHPT than in healthy controls (p<0.001). Serum periostin levels were also significantly higher (mean 59.7±11.0 ng/mL) in PHPT patients with osteoporosis than those without osteoporosis (p=0.004). In logistic regression analysis, only serum periostin levels independently predicted the patients with osteoporosis. According to this analysis, every 1 ng/mL increase in serum periostin increased the risk of having osteoporosis by 20.6%. When the cut-off for serum periostin level was 49.75 ng/mL, the patients with osteoporosis were predicted with 71.4% sensitivity and 69.2% specificity. Multivariate regression analysis revealed a negative correlation between serum periostin levels and L1-L4 T scores on DEXA.

CONCLUSION

This is the first study to determine that serum periostin levels are higher in PHPT patients than those without PHPT and to demonstrate a significant association between serum periostin levels and T scores on DEXA in patients with PHPT. These findings will aid in detecting osteoporosis in patients with PHPT and making the decision for surgery in PHPT patients with no need for DEXA imaging that involves radiation.

The bone-protective benefits of amino-conjugated calcium in an ovariectomized (OVX) rat model

Low bone density, fragility, and microarchitectural disintegration are the symptoms of osteoporosis. An imbalance between bone growth and resorption can lead to osteoporosis. This study evaluated the effects of amino-calcium (AC) on bone protection in ovariectomized control group (NC) rats. Amino-calcium (AC) was characterized using Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS), and nuclear magnetic resonance spectroscopy analyses (NMR). After determining the biocompatibility of amino-calcium (AC) with MC3T3-E1 cells, alkaline phosphatase staining revealed significant changes on day 7. Three of the four groups underwent ovariectomy, whereas one group received a placebo. On micro-computed tomography, in vivo, data showed increased bone volume fraction in the femoral head and shaft areas in the amino-calcium (AC) group. Hematoxylin and eosin staining showed a bone mass and architectural protection in the amino-calcium (AC) group compared with the calcium carbonate and OVX control group. RNA sequencing analysis revealed high expression of osteogenesis-related genes in MC3T3-E1 cells. RNA sequencing revealed a significant fold change in the expression of integrin-binding sialoprotein (IBSP), bone gamma-carboxyglutamate proteins 1 and 2(BGLAP1 and BGLAP2), and periostin (POSTN). The study concluded that supplementing the OVX rats with calcium enhanced bone protection.

Regulation of the Osteocyte Secretome with Aging and Disease

As the most numerous and long-lived of all bone cells, osteocytes have essential functions in regulating skeletal health. Through the lacunar-canalicular system, secreted proteins from osteocytes can reach cells throughout the bone. Furthermore, the intimate connectivity between the lacunar-canalicular system and the bone vasculature allows for the transport of osteocyte-secreted factors into the circulation to reach the entire body. Local and endocrine osteocyte signaling regulates physiological processes such as bone remodeling, bone mechanoadaptation, and mineral homeostasis. However, these processes are disrupted by impaired osteocyte function induced by aging and disease. Dysfunctional osteocyte signaling is now associated with the pathogenesis of many disorders, including chronic kidney disease, cancer, diabetes mellitus, and periodontitis. In this review, we focus on the targeting of bone and extraskeletal tissues by the osteocyte secretome. In particular, we highlight the secreted osteocyte proteins, which are known to be dysregulated during aging and disease, and their roles during disease progression. We also discuss how therapeutic or genetic targeting of osteocyte-secreted proteins can improve both skeletal and systemic health.

Effect of a Hop Extract Standardized in 8-Prenylnaringenin on Bone Health and Gut Microbiome in Postmenopausal Women with Osteopenia: A One-Year Randomized, Double-Blind, Placebo-Controlled Trial

Estrogen deficiency increases the risk of osteoporosis and fracture. The aim of this study was to investigate whether a hop extract standardized in 8-prenylnaringenin (8-PN), a potent phytoestrogen, could improve bone status of osteopenic women and to explore the gut microbiome roles in this effect. In this double-blind, placebo-controlled, randomized trial, 100 postmenopausal, osteopenic women were supplemented with calcium and vitamin D3 (CaD) tablets and either a hop extract (HE) standardized in 8-PN (n = 50) or a placebo (n = 50) for 48 weeks. Bone mineral density (BMD) and bone metabolism were assessed by DXA measurements and plasma bone biomarkers, respectively. Participant's quality of life (SF-36), gut microbiome composition, and short-chain fatty acid (SCFA) levels were also investigated. In addition to the CaD supplements, 48 weeks of HE supplementation increased total body BMD (1.8 ± 0.4% vs. baseline, p < 0.0001; 1.0 ± 0.6% vs. placebo, p = 0.08), with a higher proportion of women experiencing an increase ≥1% compared to placebo (odds ratio: 2.41 ± 1.07, p < 0.05). An increase in the SF-36 physical functioning score was observed with HE versus placebo (p = 0.05). Gut microbiome α-diversity and SCFA levels did not differ between groups. However, a higher abundance of genera Turicibacter and Shigella was observed in the HE group; both genera have been previously identified as associated with total body BMD. These results suggest that an 8-PN standardized hop extract could beneficially impact bone health of postmenopausal women with osteopenia.

Periostin in Osteoporosis and Cardiovascular Disease

Context

Osteoporosis (OP) and cardiovascular disease (CVD), prevalent disorders worldwide, often coexist and share common risk factors. The identification of common biomarkers could significantly improve patients' preventive care.

Objectives

The objectives are 1, to review periostin (Postn) involvement in osteoporosis and in CVD, and 2, identify if Postn could be a common biomarker.

Design

This is a scoping review on Postn in OP and CVD.

Methods

Databases were searched, in vitro and in vivo, for publications in English on Postn, bone, and the cardiovascular system, with no limit regarding publication date.

Results

Postn appears as a key factor in OP and CVD. Its role as a potential biomarker in both pathologies is described in recent studies, but a number of limitations have been identified.

Conclusions

Current evidence provides fragmented views on Postn in OP and CVD and does not encapsulate Postn as a common pivotal thread linking these comorbidities. A number of gaps impede highlighting Postn as a common biomarker. There is room for future basic and clinical research with Postn as a marker and a target to provide new therapeutic options for aging patients with concomitant OP and CVD.

Metabolome-Wide Mendelian Randomization Assessing the Causal Relationship Between Blood Metabolites and Bone Mineral Density

Mounting evidence has supported osteoporosis (OP) as a metabolic disorder. Recent metabolomics studies have discovered numerous metabolites related to bone mineral density (BMD). However, the causal effects of metabolites on BMD at distinct sites remained underexplored. Leveraging genome-wide association datasets, we conducted two-sample Mendelian randomization (MR) analyses to investigate the causal relationship between 486 blood metabolites and bone mineral density at five skeletal sites including heel (H), total body (TB), lumbar spine (LS), femoral neck (FN), and ultra-distal forearm (FA). Sensitivity analyses were performed to test the presence of the heterogeneity and the pleiotropy. To exclude the influences of reverse causation, genetic correlation, and linkage disequilibrium (LD), we further performed reverse MR, linkage disequilibrium regression score (LDSC), and colocalization analyses. In the primary MR analyses, 22, 10, 3, 7, and 2 metabolite associations were established respectively for H-BMD, TB-BMD, LS-BMD, FN-BMD, and FA-BMD at the nominal significance level (IVW, P < 0.05) and passing sensitivity analyses. Among these, one metabolite, androsterone sulfate showed a strong effect on four out of five BMD phenotypes (Odds ratio [OR] for H-BMD = 1.045 [1.020, 1.071]; Odds ratio [OR] for TB-BMD = 1.061 [1.017, 1.107]; Odds ratio [OR] for LS-BMD = 1.088 [1.023, 1.159]; Odds ratio [OR] for FN-BMD = 1.114 [1.054, 1.177]). Reverse MR analysis provided no evidence for the causal effects of BMD measurements on these metabolites. Colocalization analysis have found that several metabolite associations might be driven by shared genetic variants such as mannose for TB-BMD. This study identified some metabolites causally related to BMD at distinct sites and several key metabolic pathways, which shed light on predictive biomarkers and drug targets for OP.

Circulating Osteogenic Progenitor Cells Enhanced with Teriparatide or Denosumab Treatment

Circulating osteogenic precursor (COP) cells are peripheral blood cells with a capacity for osteogenesis. The objective of our study was to ascertain the percentage of COPs as an early biomarker of osteoporosis and the effect of these cells in response to Denosumab (DmAb) (anti-resorptive) or to Teriparatide (TPDP) (anabolic) as very effective drugs in the treatment of the illness. A first study was conducted on healthy volunteers, with three age ranges, to determine the percentage of COPs and relate it to their anthropometric and biochemical characteristics, followed by a second longitudinal study on patients with osteoporosis, whereby one group of patients was treated with TPTD and another with DmAb. All were analyzed by cytometry for COP percentage in blood, bone turnover markers, and bone mass. Our findings show that COPs are influenced by age and become more prolific in the stages of growth and skeletal maturation. A higher percentage of COPs is found in osteoporotic disease, which could constitute a predictive marker thereof. We also show how treatment with TPTD or DmAb mobilizes circulating osteogenic precursors in the blood. Significant increases in % COPs were observed after 12 months of treatment with Dmb (21.9%) and TPTD (17%). These results can be related to an increase in osteogenesis and, consequently, a better and more efficient repair of bone tissue.

Effect of physical therapy on bone remodelling in preterm infants: a multicenter randomized controlled clinical trial

Background

Preterm infants have a low level of bone mineralization compared to those born at term, since 80% of calcium incorporation occurs at the end of pregnancy. The purpose of the present study was to investigate the effect of reflex locomotion therapy on bone modeling and growth in preterm infants and to compare its effect with those of other Physiotherapy modalities.

Methods

A multicentre randomized controlled clinical trial was conducted (02/2016 – 07/2020). 106 preterm infants born at the Virgen de la Arrixaca University Clinical Hospital, the General University Hospital of Elche and the Torrecárdenas University Hospital of Almería, between 26 and 34 weeks with hemodynamic stability, complete enteral nutrition and without any metabolic, congenital, genetic, neurological or respiratory disorders were evaluated for inclusion. Infants were randomly assigned to three groups: one group received reflex locomotion therapy (EGrlt); another group received passive mobilizations with gentle joint compression (EGpmc); and the control group received massage (CG). All treatments were carried out in the neonatal units lasting one month. The main outcome measure was bone formation and resorption measured with bone biomarkers. A mixed ANOVA was used to compare the results of bone biomarkers, and anthropometric measurements.

Results

Infants were randomized to EGrlt (n = 38), EGpmc (n = 32), and CG (n = 36). All groups were similar in terms of gender (p = 0.891 female 47.2%), gestational age (M = 30.753, SD = 1.878, p = 0.39) and birth weight (M = 1413.45, SD = 347.36, p = 0.157). At the end of the study, significant differences were found between the groups in their interaction in bone formation, measured with osteocalcin [F (2,35) = 4.92, p = 0.013, η_p² = 0.043], in benefit of the EGrlt.

Conclusions

Reflex locomotion therapy has been effective in improving bone formation, more so than other Physiotherapy modalities. Therefore, reflex locomotion therapy could be considered one of the most effective physiotherapeutic modalities for the prevention and treatment of osteopenia of prematurity.

Trial registrstion

Trial retrospectively registered at ClinicalTrials.gov. First posted on 22/04/2020. Registration number: NCT04356807.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03402-2.

Dietary-Lifestyle Patterns Associated with Bone Turnover Markers, and Bone Mineral Density in Adult Male Distance Amateur Runners—A Cross-Sectional Study

Background: Excessive mileage can be detrimental to bone mineral density among long-distance runners. The negative effects of mileage could be alleviated by appropriate nutrition. The purpose of this study was to analyse the dietary-lifestyle patterns in relation to bone mineral density and bone turnover markers among amateur marathoners. Methods: A total of 53 amateur male distance runners were divided into two clusters by k-means cluster analysis. Bone mineral density was measured by dual X-ray absorptiometry (DXA). Blood was drawn to analyse bone resorption marker C-terminal telopeptide (cTX) and bone formation marker amino-terminal propeptide of type I collagen (PINP). Food frequency intake and lifestyle information were measured by multicomponent questionnaire KomPAN^®. Yearly average mileage per month was taken from each participant. Results: There were two distinguished clusters: Less-healthy-more-active-low-Z-score (LessHA) (n = 33) and More-healthy-less-active-high-Z-score (MoreHLA) (n = 20). LessHA had a lower frequency intake of pro-healthy food groups, a lower number of meals during a typical day, and a higher mileage training than the group of athletes who followed the MoreHLA. Athletes following the LessHA pattern also had a lower Z-score in the lumbar spine and femoral bone and a lower PINP. Conclusion: The current study suggests that pro-healthy dietary patterns and lower mileage may favour higher bone mineral density in male amateur marathoners.

Analysis of Serum Proteome after Treatment of Osteoporosis with Anabolic or Antiresorptive Drugs

The aim of the study was to explore new markers in serum proteome associated with the response to antiosteoporosis drugs, namely teriparatide and denosumab. We obtained serum samples from 14 patients with osteoporosis, both at baseline and after 6 months of treatment with teriparatide (n = 10) or denosumab (n = 4). Samples were analyzed by nanoliquid chromatography coupled to high-resolution mass spectrometry on a QTOF 5600 (SCIEX) apparatus. The spectrometry data were analyzed with Mascot against the UniProtKB base and then several quality-control filters were applied for the identification of peptides (false discovery rate, FDR q < 0.02) and their quantification (FDR q < 0.05). In the group treated with teriparatide, 28 proteins were identified with significant differences before and after treatment. A pathway analysis by using the Reactome database revealed significant enrichment in the Insulin Like Growth Factor 1 (IGF-I) (FDR q 4 × 10−2) and innate immune system (FDR q 2 × 10−3) pathways. Among patients treated with denosumab, we observed significant differences in the levels of 10 proteins, which were also enriched in the pathways related to the innate immune system (FDR q 3 × 10−2). These results suggest that the innate immune system may be involved in the response to antiosteoporosis drugs.

Management of patients at very high risk of osteoporotic fractures through sequential treatments

Osteoporosis care has evolved markedly over the last 50 years, such that there are now an established clinical definition, validated methods of fracture risk assessment and a range of effective pharmacological agents. Currently, bone-forming (anabolic) agents, in many countries, are used in those patients who have continued to lose bone mineral density (BMD), patients with multiple subsequent fractures or those who have fractured despite treatment with antiresorptive agents. However, head-to-head data suggest that anabolic agents have greater rapidity and efficacy for fracture risk reduction than do antiresorptive therapies. The European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) convened an expert working group to discuss the tools available to identify patients at high risk of fracture, review the evidence for the use of anabolic agents as the initial intervention in patients at highest risk of fracture and consider the sequence of therapy following their use. This position paper sets out the findings of the group and the consequent recommendations. The key conclusion is that the current evidence base supports an "anabolic first" approach in patients found to be at very high risk of fracture, followed by maintenance therapy using an antiresorptive agent, and with the subsequent need for antiosteoporosis therapy addressed over a lifetime horizon.

Identification of Potential Osteoporosis miRNA Biomarkers Using Bioinformatics Approaches

Osteoporosis is a degenerative osteoarthropathy commonly found in old people and postmenopausal women. Many studies showed that microRNAs (miRNAs) can regulate the expression of osteoporosis-related genes and are abnormally expressed in patients with osteoporosis. miRNAs therefore have the potential to serve as biomarkers of osteoporosis. In this study, the limma package was used for the differential expression analysis of mRNA expression profiles and 357 significantly differentially expressed genes (DEGs) were obtained. Metascape was used for functional enrichment analysis of DEGs. The result revealed that DEGs were mainly enriched in signaling pathways like MAPK6/MAPK4. Based on the STRING database, the protein-protein interaction (PPI) network of DEGs was constructed. MCODE was used to analyze the functional subsets, and a key functional subset composed of 9 genes was screened out. In addition, the miRNA-mRNA regulatory interaction network (RegIN) was analyzed by the CyTargetLinker plugin, which generated 55 miRNA-mRNA regulatory interactions. Through literature searching, the osteoporosis-related gene FOXO1 in the key functional subset was determined to be the main object of the study. In qRT-PCR assay, the expression of the predicted miRNAs was tested in peripheral blood mononuclear cells of mice with osteoporosis, in which 13 miRNAs were remarkably highly expressed. All in all, this study, based on bioinformatics analysis and testing assay of miRNA expression, determined the potential biomarkers of osteoporosis.

Higher Levels of Circulating Osteoprogenitor Cells Are Associated With Higher Bone Mineral Density and Lean Mass in Older Adults: A Cross-Sectional Study

Circulating osteo progenitor (COP) cells are a heterogeneous population of cells that circulate within the peripheral blood with characteristics of the bone marrow mesenchymal stem and progenitor pool. Little is known about the behavior of this cell population in humans. The aim of this study was to identify whether a relationship exists between COP cells (as a percentage of the peripheral blood monocytic cells) and musculoskeletal morphometry and to identify if COP have potential clinical utility as a biomarker for osteoporosis. We recruited 57 older adults (median age: 69 years; IQR: 65, 75 years) living independently in the community and performed cross‐sectional analysis to identify associations between the percentage of COP cells and body composition parameters, and through receiver operating characteristic analysis, we evaluated their ability to act as a biomarker of osteoporosis. COP cells were moderately associated with whole‐body bone mineral density (BMD) (r = 0.323, p = 0.014) and bone mineral content (BMC) (r = 0.387, p = 0.003), neck of femur BMD (r = 0.473, p < 0.001), and BMC (r = 0.461, p < 0.001) as well as appendicular lean mass (ALM) (p = 0.038) and male sex (p = 0.044) in univariable analysis. In multivariable analysis controlling for age, gender, height, and weight, COP cells remained strongly associated with neck of femur BMD (p = 0.001) and content (p = 0.003). COP cells were also a good predictor of osteoporosis (dual‐energy X‐ray absorptiometry [DXA] T‐score < −2.5) at the neck of femur (cutoff: 0.4%; sensitivity: 100%; specificity 79%) and total body (cutoff: 0.35%; sensitivity: 80%; specificity: 81%). This study shows strong relationships between bone parameters and COP cell number and male sex. They also have potential as a biomarker of osteoporosis, which may provide a new tool for advanced detection and screening in clinical settings. Future larger evaluation studies should verify the cutoffs for biomarker use, and further explore the relationship between COP cells and muscle. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Serum levels of irisin in postmenopausal women with osteoporotic hip fractures

OBJECTIVE

The purpose of this study was to evaluate the role of circulating serum levels of irisin in predicting hip fracture occurrence in a cohort of Chinese postmenopausal women.

METHODS

This was a cross-section and case-control study. Four hundred and thirty postmenopausal women aged 50-90 years were included (215 with hip fractures and 215 age-matched cases without fracture). Clinical features, bone mineral density (BMD) and serum biomarkers levels including irisin were measured at baseline. Cox proportional hazards regression analysis was used to assess the correlation between irisin and fracture risk.

RESULTS

The mean age of those participants was 68.7 (S.D. 11.7) and 53.0% were order than 65. The irisin serum levels were positively related to total body BMD and total hip BMD. Women with hip fractures showed lower mean serum levels of irisin compared normal control women (457.6 ± 172.6 ng/ml vs. 602.2 ng/ml; P < 0.001). The irisin levels in third and fourth quartiles were associated with the risk of hip fracture (the lowest quartile of irisin levels as the reference), and risk of fracture reduced by 67% (hazard ratio [HR] = 0.33; 95 %CI: 0.18-0.54; P < 0.001) and 84% (HR = 0.16; 95 %CI: 0.09-0.29; P < 0.001). The irisin levels in third and fourth quartiles were also associated with the risk of osteoporosis, and risk of fracture reduced by 55% (HR = 0.45; 95 %CI: 0.21-0.63; P = 0.003) and 73% (HR = 0.27; 95 %CI: 0.15-0.47; P < 0.001).

CONCLUSION

Decreased serum levels of circulating irisin are associated with high risk of osteoporosis-related hip fractures and osteoporosis.

Periostin: An Emerging Molecule With a Potential Role in Spinal Degenerative Diseases

Periostin, an extracellular matrix protein, is widely expressed in a variety of tissues and cells. It has many biological functions and is related to many diseases: for example, it promotes cell proliferation and differentiation in osteoblasts, which are closely related to osteoporosis, and mediates cell senescence and apoptosis in chondrocytes, which are involved in osteoarthritis. Furthermore, it also plays an important role in mediating inflammation and reconstruction during bronchial asthma, as well as in promoting bone development, reconstruction, repair, and strength. Therefore, periostin has been explored as a potential biomarker for various diseases. Recently, periostin has also been found to be expressed in intervertebral disc cells as a component of the intervertebral extracellular matrix, and to play a crucial role in the maintenance and degeneration of intervertebral discs. This article reviews the biological role of periostin in bone marrow-derived mesenchymal stem cells, osteoblasts, osteoclasts, chondrocytes, and annulus fibrosus and nucleus pulposus cells, which are closely related to spinal degenerative diseases. The study of its pathophysiological effects is of great significance for the diagnosis and treatment of spinal degeneration, although additional studies are needed.

Sex-related differences in bone metabolism in osteoporosis observational study

Although the incidence is lower in men than women, osteoporosis remains a significant health issue in men as it may give rise to severe complications if not managed appropriately. As men and women show different biological and social backgrounds, we retrospectively evaluated the differences in the bone metabolism between men and women using bone biomarkers.Bone mineral density (BMD) was determined in all patients using dual-energy X-ray absorptiometry (DXA) and analyzing various bone biomarkers such as carboxyl-terminal collagen crosslinks (CTX), osteocalcin (OCT), and alkaline phosphatase (ALP). The CTX/OCT ratio was used to estimate the association between bone absorption and formation.OCT, CTX, and ALP levels were elevated in patients with osteoporosis. Women displayed a higher incidence of osteoporosis and greater reduction in BMD than men. The mean OCT level in men was lower than that in women. Moreover, men showed significantly lower OCT levels than women of aged 65 and under 80 years old. Among patients with osteoporosis, men had a higher ratio of bone markers than women.Levels of biomarkers of bone formation and absorption were increased in the osteoporosis group. However, men showed lower increases in bone formation biomarkers than did women, indicating that the rate of bone formation relative to bone absorption did not increase in men compared with that in women. Therefore, we suggest that men and women have different bone metabolism in old age.

Serum N-terminal telopeptide of type I collagen as a biomarker for predicting bone density loss in patients with Crohn disease

BACKGROUND

The serum N-terminal telopeptide of type I collagen (NTx) is significantly higher in patients with Crohn disease (CD) than in healthy individuals and patients with ulcerative colitis. This study aimed to investigate whether an elevated serum NTx level is a risk predictor of osteoporosis in patients with CD.

METHODS

Based on whether the femoral Z-score decreased over a 2-year period, 41 CD patients were divided into the ΔZ-score <0 group (Z-score decreased) and the ΔZ-score ≥0 group (Z-score did not decrease). The risk predictors of a femoral Z-score decrease were examined. Furthermore, we investigated the correlations between the ΔZ-score (which represents the change in the Z-score over a 2-year period) and the mean levels of biomarkers, including the Crohn Disease Activity Index (CDAI), serum albumin, C-reactive protein, and bone metabolism markers (including NTx) measured initially (i.e., in our previous study) and 2 years later (present study). The relationships between anti-tumor necrosis factor α (anti-TNF-α) therapy and serum NTx levels were also examined.

RESULTS

Although there was no correlation between the mean CDAI and the ΔZ-score, the mean serum NTx and albumin levels were significantly correlated with the ΔZ-score (P<0.01 and P = 0.02, respectively). Furthermore, the femoral Z-score tended to be lower in the anti-TNF-α administration group than in the non-administration group.

CONCLUSIONS

These observations indicated that an elevated serum NTx could be a useful marker for predicting a decrease in the femoral bone mineral density in CD patients. Anti-TNF-α therapy maintained an elevated serum NTx level, suggesting that treatment with anti-TNF-α may help control increased bone resorption in CD patients.

Serum levels of bone formation and resorption markers in relation to vitamin D status in professional gymnastics and physically active men during upper and lower body high-intensity exercise

Purpose/introduction

To compare serum levels of bone turnover markers in athletes and non-athletes, and to evaluate the relationship between serum levels of vitamin D metabolites and exercise-induced changes in biomarker levels.

Methods

Sixteen elite male artistic gymnasts (EG; 21.4 ± 0.8 years-old) and 16 physically active men (the control group, PAM; 20.9 ± 1.2 years-old) performed lower and upper body 30-s Wingate anaerobic tests (LBWT and UBWT, respectively). For biomarker analysis, blood samples were collected before, and 5 and 30 min after exercise. Samples for vitamin D levels were collected before exercise. N-terminal propeptide of type I collagen (PINP) was analysed as a marker of bone formation. C-terminal telopeptide of type I collagen (CTX) was analysed as a marker of bone resorption.

Results

UBWT fitness readings were better in the EG group than in the PAM group, with no difference in LBWT readings between the groups. UBWT mean power was 8.8% higher in subjects with 25(OH)D₃ levels over 22.50 ng/ml and in those with 24,25(OH)₂D₃ levels over 1.27 ng/ml. Serum CTX levels increased after both tests in the PAM group, with no change in the EG group. PINP levels did not change in either group; however, in PAM subjects with 25(OH)D₃ levels above the median, they were higher than those in EG subjects.

Conclusion

Vitamin D metabolites affect the anaerobic performance and bone turnover markers at rest and after exercise. Further, adaptation to physical activity modulates the effect of anaerobic exercise on bone metabolism markers.

Changes in bone formation regulator biomarkers in early axial spondyloarthritis

OBJECTIVE

The hallmark of advanced axial SpA (axSpA) is spine ankylosis due to excessive ectopic bone formation. This prospective study aimed to describe the changes in serum levels of different regulators [sclerostin, dickkopf-1 (DKK-1)] and markers of bone formation [bone morphogenetic protein 7 (BMP-7)] over 5 years in early axSpA patients and to assess determinants of such changes.

METHODS

The DEvenir des Spondyloarthropathies Indifférenciées Récentes cohort is a prospective, multicentre French study of 708 patients with early (>3 months-<3 years) inflammatory back pain suggestive of axSpA. Serum levels of BMP-7, sclerostin and DKK-1 were assessed at baseline and after 2 and 5 years. Changes in bone formation regulators over time were analysed using mixed linear models.

RESULTS

Serum BMP-7 significantly increased over time, with a median relative change of 223.7% [interquartile range (IQR) 0-10 700 (0.17 pg/ml/month), P < 0.001]. Serum sclerostin significantly increased over time, with a median relative change of 14.8% [IQR -7.9-41.4% (0.001 ng/ml/month), P < 0.001]. Serum DKK-1 did not significantly change over time. Serum BMP-7 increased over time in active disease (Ankylosing Spondylitis Disease Activity Score with CRP ≥1.3, P = 0.01), but the increase was less pronounced with TNF inhibitor (TNFi) use (P < 0.001). No determinant was associated with serum sclerostin change.

CONCLUSION

Serum BMP-7 change over 5 years was related with inflammation; it was increased in active disease, but the increase was low with TNFi use. Serum sclerostin levels significantly increased over time, but to a lesser degree than for serum BMP-7.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/, NCT01648907.

Increased Bone Resorption during Lactation in Pycnodysostosis

Pycnodysostosis, a rare autosomal recessive skeletal dysplasia, is caused by a deficiency of cathepsin K. Patients have impaired bone resorption in the presence of normal or increased numbers of multinucleated, but dysfunctional, osteoclasts. Cathepsin K degrades collagen type I and generates N-telopeptide (NTX) and the C-telopeptide (CTX) that can be quantified. Levels of these telopeptides are increased in lactating women and are associated with increased bone resorption. Nothing is known about the consequences of cathepsin K deficiency in lactating women. Here we present for the first time normalized blood and CTX measurements in a patient with pycnodysostosis, exclusively related to the lactation period. In vitro studies using osteoclasts derived from blood monocytes during lactation and after weaning further show consistent bone resorption before and after lactation. Increased expression of cathepsins L and S in osteoclasts derived from the lactating patient suggests that other proteinases could compensate for the lack of cathepsin K during the lactation period of pycnodysostosis patients.

Association between the metabolome and bone mineral density in a Chinese population

BACKGROUND

Osteoporosis is a common metabolic bone disease, which always leads to osteoporotic fractures. Biomarkers of bone mineral density (BMD) are helpful for prevention and early diagnosis of osteoporosis. This study aims to identify metabolomic biomarkers of low BMD.

METHODS

We included 701 participants who had BMD measures by dual-energy X-ray absorptiometry scans and donated fasting plasma samples from three clinical centres as a discovery set and another 278 participants from the fourth centre as an independent replication set. We used a liquid chromatography-mass spectrometry-based metabolomics approach to profile the global metabolites of fasting plasma.

FINDINGS

Among the 265 named metabolites identified in our study, six were associated with low BMD (FDR-adjusted P<0.05) in the discovery set and were successfully validated in the independent replication set. The circulating levels of five metabolites, i.e., inosine, hypoxanthine, PC (O-18:0/22:6), SM (d18:1/21:0) and isoleucyl-proline were associated with decreased odds of low BMD, and PC (16:0/18:3) level was associated with increased odds of low BMD. Per 1-SD increase in a composite metabolite score of these six metabolites was associated with about half decreased odds of low BMD (odds ratio 0.59, 95% confidence interval: 0.52-0.68). Furthermore, introduction of a panel of metabolites selected by elastic net regression to a prediction model of classical risk factors and plasma biomarker of bone resorption substantially improved the prediction performance for low BMD (AUCs: 0.782 vs. 0.698, P=0.002).

INTERPRETATION

Metabolomics profiling may help identify novel biomarkers of low BMD and be helpful for early diagnosis of osteoporosis beyond the current clinical index.

FUNDING

This study was supported by the National Key R&D Program of China [2018YFC2001500 to J.S.], Shanghai Municipal Science and Technology Major Project [2017SHZDZX01], the National Natural Science Foundation of China [Key Program, 91749204 to J.S.], the National Natural Science Foundation of China [General Program, 81771491 to J.S.], the Project of Shanghai Subject Chief Scientist [2017BR011 to J.S.], Grants from the TCM Supported Project [18431902300 to J.S.] from the Science and Technology Commission of Shanghai Municipality, and the National Natural Science Foundation of China [General Program, 81972089 to Z.X.]. Y.Z. was supported by the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, and the National Natural Science Foundation of China [81973032].

Status of circulating bone turnover markers in elderly osteoporosis/osteopenia patients in comparison with healthy subjects

Background

In the aging individuals, osteoporosis is a major health problem. Due to the various limitations of dual X-ray absorptiometry (DEXA) for diagnosis osteoporosis, serum-based biochemical markers have been suggested for the discrimination between the patients and healthy subjects.

Objective

To investigate the serum levels of bone turnover markers in elderly osteoporosis patients.

Methods

The serum samples from elderly subjects (osteoporosis (n = 28), osteopenia (n = 28), and healthy ones (n = 28) were collected from Amirkola Health and Ageing Project study. Furthermore, serum levels of bone formation and bone resorption markers as well as estrogen and progesterone were measured by enzyme-linked immunosorbent assay. Kruskal–Wallis test and receiver operating characteristic curve analysis were used for statistical analysis using SPSS.

Results

Levels of bone alkaline phosphatase (B-ALP) and procollagen type I N-terminal propeptide (PINP) differed between groups (P = 0.003 and 0.009, respectively). Furthermore, PINP and B-ALP levels had the best area under the curve, sensitivity, and specificity for the discrimination between patients with osteoporosis and healthy individuals.

Conclusion

In conditions in which we are not able to assess the bone mineral density by DEXA, analysis of the B-ALP and PINP levels may be a helpful tool.

The role of biochemical markers of joint tissue remodelling to predict progression and treatment efficacy in inflammatory rheumatic diseases

Structural damage is a hallmark in RA, spondyloarthropy (SpA) and psoriatric arthritis (PsA). Its progression is difficult to predict and current radiological or inflammatory biological markers lack sensitivity. Biochemical markers of bone, cartilage and synovial tissues provide a dynamic indication of the anabolism and catabolism of joint tissues and can be easily measured by immunoassays. Novel biochemical markers including post-translational modifications of matrix proteins and enzyme-generated neoepitopes with increased tissue and/or biological pathway specificity have been developed. Their evaluation in clinical trials of novel biologic therapies and epidemiological studies indicated that their measurements could be useful to predict progression of structural damage and treatment efficacy, independently of current clinical, radiological and biological indices of disease activity. In this paper we briefly describe the latest developments in biochemical markers and critically analyse the clinical data assessing the utility of established and novel biochemical markers in RA, SpA and PsA.

Practical management of fracture risk among peri- and postmenopausal women

Fractures and their consequences are the clinically important manifestation of osteoporosis; preventing fractures is the primary goal of management. Effective management is achievable given present knowledge and tools but is seldom prescribed. This review will cover the individual and social burden of fracture, essential information about fracture risk and its estimation, an approach to patient care emphasizing specific information to elicit and therapeutic strategies to pursue, and existing gaps in knowledge and important questions for future research.

Decreased markers of bone turnover in children and adolescents with type 1 diabetes

BACKGROUND AND AIM

Adults with type 1 diabetes (T1D) have increased risk of bone fractures and decreased bone mineral density (BMD). Alterations in bone turnover have been suggested as the link between T1D and the impaired bone health. Furthermore, bone turnover has been suggested to have beneficial effects on glucose metabolism. This study aimed at describing bone turnover markers (BTM), and the relationship with glycemic control, in children and adolescents with T1D.

METHODS

A total of 173 (47% girls) children and adolescents aged 7.7 to 17.5 years with T1D for more than 1 year were included. Participants were evaluated by BMD together with measurements of selected BTM; two formation markers: osteocalcin (OCN) and procollagen type-1 amino-terminal propeptide (P1NP) and one resorption marker, C-terminal cross-linked telopeptide of type-1 collagen (CTX). BTM were converted into Z-scores utilizing new national references.

RESULTS

Mean OCN Z-score (-0.68 ± 1.31), P1NP Z-score (-0.33 ± 1.03) and CTX Z-score (-0.43 ± 1.10) were all significantly lower than the reference population (P < .001). No associations were seen between BTM and T1D duration. BMD Z-score was comparable to the reference population and associated with none of individual BTMs. CTX Z-score was negatively associated with HbA1c (P = .007) independent of both exogenous and residual endogenous insulin.

CONCLUSIONS

Markers of bone formation and resorption were decreased in children and adolescents with T1D. CTX Z-score associated negatively with HbA1c adjusted for insulin treatment and endogenous insulin production indicating a potential association between CTX and insulin sensitivity. The long-term consequences of decreased BTM on BMD need further attention.

Characterization of Dysregulated lncRNA-Associated ceRNA Network Reveals Novel lncRNAs With ceRNA Activity as Epigenetic Diagnostic Biomarkers for Osteoporosis Risk

The altered expression of long non-coding RNAs (lncRNAs) has been implicated in the development and human diseases. However, functional roles and regulatory mechanisms of lncRNA as competing endogenous RNAs (ceRNAs) in osteoporosis and their potential clinical implication for osteoporosis risk are largely unexplored. In this study, we performed integrated analysis for paired expression profiles and regulatory relationships of dysregulated lncRNAs, mRNAs, and miRNAs based on “ceRNA hypothesis,” and constructed an osteoporosis-related dysregulated miRNA-mediated lncRNA–mRNA ceRNA network (DysCeNet) composed of 105 nodes (including eight miRNAs, 24 mRNAs, and 73 lncRNAs) and 515 edges. Functional analysis suggested that the DysCeNet was involved in known osteoporosis or bone metabolism-related biological processes and pathways. Then, we performed random forest-based feature selection for 73 lncRNAs with ceRNA activity and identified 25 of 73 lncRNAs as potential diagnostic biomarkers. A random forest-based classifier composed of 25 lncRNA biomarkers (RF-25lncRNA) was developed for predicting osteoporosis risk. Performance evaluation with the leave-one-out cross-validation (LOOCV) procedure showed that the RF-25lncRNA achieved a good performance in distinguishing high- and low-bone mineral density (BMD) subjects in different osteoporosis datasets. Our study for the first time revealed a global view of lncRNA-associated ceRNA regulation in osteoporosis and provided novel lncRNAs with ceRNA activity as candidate epigenetic diagnostic biomarkers for early detection of osteoporosis risk.

MicroRNA Alterations for Diagnosis, Prognosis, and Treatment of Osteoporosis: A Comprehensive Review and Computational Functional Survey

Osteoporosis (OP) is a systemic bone disease with a series of clinical symptoms. The use of screening biomarkers in OP management is therefore of clinical significance, especially in the era of precision medicine and intelligent healthcare. MicroRNAs (miRNAs) are small, non-coding RNAs with the potential to regulate gene expression at the post-transcriptional level. Accumulating evidence indicates that miRNAs may serve as biomarkers for OP prediction and prevention. However, few studies have emphasized the role of miRNAs in systems-level pathogenesis during OP development. In this article, literature-reported OP miRNAs were manually collected and analyzed based on a systems biology paradigm. Functional enrichment studies were performed to decode the underlying mechanisms of miRNAs in OP etiology and therapeutics in three-dimensional space, i.e., integrated miRNA–gene–pathway analysis. In particular, interactions between miRNAs and three well-known OP pathways, i.e., estrogen–endocrine, WNT/β-catenin signaling, and RANKL/RANK/OPG, were systematically investigated, and the effects of non-genetic factors on personalized OP prevention and therapy were discussed. This article is a comprehensive review of OP miRNAs, and bridges the gap between an understanding of OP pathogenesis and clinical translation.

Potential Biomarkers to Improve the Prediction of Osteoporotic Fractures

Osteoporotic fracture (OF) is associated with high disability and morbidity rates. The burden of OF may be reduced by early identification of subjects who are vulnerable to fracture. Although the current fracture risk assessment model includes clinical risk factors (CRFs) and bone mineral density (BMD), its overall ability to identify individuals at high risk for fracture remains suboptimal. Efforts have therefore been made to identify potential biomarkers that can predict the risk of OF, independent of or combined with CRFs and BMD. This review highlights the emerging biomarkers of bone metabolism, including sphongosine-1-phosphate, leucine-rich repeat-containing 17, macrophage migration inhibitory factor, sclerostin, receptor activator of nuclear factor-κB ligand, and periostin, and the importance of biomarker risk score, generated by combining these markers, in enhancing the accuracy of fracture prediction.

Bone turnover markers during the remission phase in children and adolescents with type 1 diabetes

BACKGROUND AND AIM

In rodents, osteocalcin (OCN) stimulates insulin production and insulin sensitivity, both important factors during partial remission in humans with type 1 diabetes (T1D). However, decreased OCN has been reported in both adult and pediatric T1D. This study aims at investigating bone turnover and partial remission in children and adolescents with recent onset T1D.

SUBJECTS AND METHODS

Ninety-nine individuals (33% girls) were recruited within 3 months of T1D onset and examined three times, 6 months apart. Outcome variables were bone formation markers OCN and procollagen type 1 amino-terminal propeptide (P1NP) and the bone resorption marker C-terminal crosslinked telopeptide of type 1 collagen (CTX). Dependent variables included IDAA1c (surrogate marker of partial remission), total body bone mineral density (BMD) and stimulated C-peptide as representative of endogenous insulin production.

RESULTS

OCN- and P1NP Z-scores were significantly decreased throughout the study, whereas CTX Z-scores were increased. None of the bone turnover markers changed significantly between visits. Total body BMD Z-score did not change during the study but was significantly higher than the reference population at visit 2 (P = .035). There were no differences in the bone turnover markers for those in partial remission as defined by either C-peptide or IDAA1c at any visit. The individual change in CTX Z-score was negatively associated with the increase of IDAA1c (P = .030) independent of C-peptide decline (P = .034).

CONCLUSION

Bone turnover markers indicate increased bone resorption and decreased bone formation during the first year of T1D. The negative association between bone resorption and IDAA1c might represent compensatory mechanisms affecting insulin sensitivity.

MicroRNA levels in bone and blood change during bisphosphonate and teriparatide therapy in an animal model of postmenopausal osteoporosis

MicroRNAs control the activity of a variety of genes that are pivotal to bone metabolism. Therefore, the clinical utility of miRNAs as biomarkers and drug targets for bone diseases certainly merits further investigation. This study describes the use of an animal model of postmenopausal osteoporosis to generate a comprehensive dataset on miRNA regulation in bone tissue and peripheral blood during bone loss and specifically anti-resorptive and osteo-anabolic treatment. Forty-two Sprague-Dawley rats were randomized to SHAM surgery (n=10) or ovariectomy (OVX, n=32). Eight weeks after surgery, OVX animals were further randomized to anti-resorptive treatment with zoledronate (n=11), osteo-anabolic treatment with teriparatide (n=11), or vehicle treatment (n=10). After 12 weeks of treatment, bone and serum samples were used for microRNA analysis using next-generation sequencing (NGS), mRNA levels using RT-qPCR, and bone microarchitecture analysis using nanoCT. Ovariectomy resulted in loss of trabecular bone, which was fully rescued using osteo-anabolic treatment, and partially rescued using anti-resorptive treatment. NGS revealed that both, anti-resorptive and anabolic treatment had a significant impact on miRNA levels in bone tissue and serum: out of 426 detected miRNAs, 46 miRNAs were regulated by teriparatide treatment an d 10 by zoledronate treatment (p-adj.<0.1). Interestingly, teriparatide and zoledronate treatment were able to revert miRNA changes in tissue and serum of untreated OVX animals, such as the up-regulation of miR-203a-3p, a known osteo-inhibitory miRNA. We confirmed previously established mechanisms of miR-203a by analyzing its direct target Dlx5 in femoral head. Our data reveal a significant effect of ovariectomy-induced bone loss, as well as the two major types of anti-osteoporotic treatment on miRNA transcription in femoral head tissue. These changes are associated with altered activity of target genes relevant to bone formation, such as Dlx5. The observed effects of bone loss and treatment response on miRNA levels in bone are also reflected in the peripheral blood, suggesting the possibility of minimally-invasive monitoring of bone-derived miRNAs using liquid biopsies.

Viewpoint on the role of tissue maintenance in ageing: focus on biomarkers of bone, cartilage, muscle, and brain tissue maintenance

Specific hallmarks are thought to underlie the ageing process and age-related functional decline. In this viewpoint, we put forward the hypothesis that disturbances in the process of tissue maintenance are an important common denominator that may lie in between specific hallmarks of ageing (i.e. damage and responses to damage) and their ultimate (patho)physiological consequences (i.e. functional decline and age-related disease). As a first step towards verifying or falsifying this hypothesis, it will be important to measure biomarkers of tissue maintenance in future studies in different study populations. The main aim of the current paper is to discuss potential biomarkers of tissue maintenance that could be used in such future studies. Among the many tissues that could have been chosen to explore our hypothesis, to keep the paper manageable, we chose to focus on a selected number of tissues, namely bone, cartilage, muscle, and the brain, which are important for mobility and cognition and affected in several common age-related diseases, including osteoporosis, osteoarthritis, sarcopenia, and neurodegenerative diseases. Furthermore, we discuss the advantages and limitations of potential biomarkers for use in (pre)clinical studies. The proposed biomarkers should be validated in future research, for example by measuring these in humans with different rates of ageing.

Higher concentration of serum C-terminal cross-linking telopeptide of type I collagen is positively related with inflammatory factors in postmenopausal women with H-type hypertension and osteoporosis

OBJECTIVE

To investigate the changes of inflammatory factors and bone metabolism markers in postmenopausal women with H-type hypertension and to assess the relationship between them.

METHODS

Postmenopausal women who were diagnosed with osteoporosis were selected as observation objects. Participants were divided into three groups: only osteoporosis group (osteoporosis group), hypertension combined with osteoporosis group (hypertension group), and H-type hypertension combined with osteoporosis group (H-type hypertension group). The changes in bone mineral density and bone metabolic markers (osteocalcin [OC], procollagen type I N-terminal propeptide (PINP), and C-terminal cross-linking telopeptide of type I collagen [CTX]) and inflammatory factors (interleukin-6 [IL-6] and tumor necrosis factor-α [TNF-α]) were compared among three groups.

RESULTS

In the hypertension group and the H-type hypertension group, the bone mineral density of the lumbar spine (0.647 ± 0.038 vs 0.638 ± 0.034 vs 0.668 ± 0.047, P < 0.05) and the femoral neck (0.567 ± 0.047 vs 0.552 ± 0.053 vs 0.618 ± 0.059, P < 0.05) was significantly lower than that in the osteoporosis group. The concentrations of CTX (266.61 ± 64.65 vs 293.09 ± 72.34 vs 235.48 ± 62.85, P < 0.05), IL-6 (44.36 ± 6.45 vs 48.05 ± 8.04 vs 39.06 ± 7.95, P < 0.05) and TNF-α (30.53 ± 6.28 vs 34.52 ± 7.15 vs 28.66 ± 6.19, P < 0.01) in the hypertension group and in the H-type hypertension group were significantly higher than those in the osteoporosis group. The concentrations of OC (30.59 ± 6.43 vs 27.10 ± 6.51, P < 0.05) and PINP (36.36 ± 6.16 vs 33.16 ± 6.77, P < 0.05) in the H-type hypertension group were increased dramatically. The concentration of CTX was positively correlated with the concentration of IL-6 (r = 0.587, P < 0.01) and TNF-α (r = 0.474, P < 0.01) and negatively related with the concentration of OC (r = -0.591, P < 0.01) and PINP (r = -0.646, P < 0.01) and the bone mineral density of the lumbar spine (r = -0.470, P < 0.01) and the femoral neck (r = -0.509, P < 0.01).

CONCLUSION

Higher concentration of serum CTX is found in postmenopausal women with H-type hypertension, which is positively correlated with inflammatory factors. Besides, H-type hypertension could further enhance the activity of osteoclasts and increase the expressions of inflammatory factors, resulting in the aggravation of osteoporosis.

Serum Proteomic Analysis Reveals Vitamin D-Binding Protein (VDBP) as a Potential Biomarker for Low Bone Mineral Density in Mexican Postmenopausal Women

Osteoporosis is a skeletal disease mainly affecting women over 50 years old and it represents a serious public health problem because of the high socioeconomic burden. This disease is characterized by deterioration of bone microarchitecture, low bone mineral density (BMD), and increased risk of fragility fractures. This study aimed to identify serum useful proteins as biomarkers for the diagnosis and/or prognosis of osteoporosis and fracture risk. We collected 446 serum samples from postmenopausal women aged ≥45 years old. Based on the BMD measurement, we classified the participants into three groups: osteoporotic, osteopenic, and normal. In an initial discovery stage, we conducted a proteomic approach using two-dimensional differential gel electrophoresis (2D-DIGE). The peptides into the spots of interest were identified through matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF/TOF). Enzyme-linked immunosorbent assay (ELISA) was performed to validate the proteins of interest. We identified 27 spots of interest when comparing low BMD versus normal BMD postmenopausal women. Based on their relevance in bone metabolism, we analyzed three proteins: ceruloplasmin (CP), gelsolin (GSN), and vitamin D-binding protein (VDBP). Our results demonstrated that low serum VDBP levels correlate with low BMD (osteopenic and osteoporotic). Therefore, VDBP could be considered as a novel, potential, and non-invasive biomarker for the early detection of osteoporosis.

Serum C-C Motif Ligand 11/eotaxin-1 May Serve as a Candidate Biomarker for Postmenopausal Osteoporosis

Background

The chemokine C-C motif ligand 11, also known as eotaxin-1, has been identified as a novel mediator of inflammatory bone resorption. However, little is known regarding a potential role for CCL11/Eotaxin-1 in postmenopausal osteoporosis.

Objective

The scope of this study was to explore the relationship between serum CCL11/Eotaxin-1 concentrations and disease progression of postmenopausal females with osteoporosis.

Methods

A total of 83 postmenopausal women diagnosed with osteoporosis were enrolled. Meanwhile, 82 postmenopausal women with normal bone mineral density (BMD) and 85 healthy controls inner child-bearing age were enrolled as control. The Dual-energy X-ray absorptiometry was used to examine the BMDs at the femoral neck, lumbar spine 1-4 and total hip of all participants. Serum CCL11/Eotaxin-1 levels were examined by enzyme-linked immunosorbent assay. We also included inflammation marker interleukin-6 (IL-6) as well as a serum marker of bone resorption C-telopeptide cross-linked collagen type 1 (CTX-1). The Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) were recorded to evaluate the clinical severity in POMP females.

Results

Serum CCL11/Eotaxin-1 levels were significantly elevated in postmenopausal osteoporotic patients PMOP patients compared with PMNOP and healthy controls. We observed a significant negative correlation of serum CCL11/Eotaxin-1 levels with lumbar spine, femoral neck and total hip BMD. Furthermore, serum CCL11/ Eotaxin-1 concentrations were also positively related to the VAS and ODI scores. Last, serum CCL11/ Eotaxin-1 concentrations were positively associated with IL-6 and CTX-1 levels. These correlations remain significant after adjusting for age and BMI. Multivariate linear regression analysis demonstrated that CCL11/Eotaxin-1 could serve as an independent marker.

Conclusions

Serum CCL 11/Eotaxin-1 may serve as a candidate biomarker for postmenopausal osteoporosis. Therapeutics targeting CCL11/Eotaxin-1 and its related signalling way to prevent and slow progression of PMOP deserve further study.

The Therapeutic Potential of MicroRNAs as Orthobiologics for Skeletal Fractures

The repair of a fractured bone is critical to the well-being of humans. Failure of the repair process to proceed normally can lead to complicated fractures, exemplified by either a delay in union or a complete nonunion. Both of these conditions lead to pain, the possibility of additional surgery, and impairment of life quality. Additionally, work productivity decreases, income is reduced, and treatment costs increase, resulting in financial hardship. Thus, developing effective treatments for these difficult fractures or even accelerating the normal physiological repair process is warranted. Accumulating evidence shows that microRNAs (miRNAs), small noncoding RNAs, can serve as key regulatory molecules of fracture repair. In this review, a brief description of the fracture repair process and miRNA biogenesis is presented, as well as a summary of our current knowledge of the involvement of miRNAs in physiological fracture repair, osteoporotic fractures, and bone defect healing. Further, miRNA polymorphisms associated with fractures, miRNA presence in exosomes, and miRNAs as potential therapeutic orthobiologics are also discussed. This is a timely review as several miRNA-based therapeutics have recently entered clinical trials for nonskeletal applications and thus it is incumbent upon bone researchers to explore whether miRNAs can become the next class of orthobiologics for the treatment of skeletal fractures.

The 24-hour serum profiles of bone markers in healthy older men and women

The process of bone turnover displays variations over 24 h, with C-terminal cross-linked telopeptide of type 1 collagen (CTX) and osteocalcin exhibiting a nadir in the afternoon and a peak in the night. In contrast, N-terminal propeptide of type 1 procollagen (P1NP) did not display an apparent 24-hour rhythm. Other emerging novel biomarkers of bone, sclerostin and Dickkopf-related protein 1 (DKK1), are markers of osteocyte activity with limited data available regarding their 24-hour profiles. In this study, we aimed to extend available data on 24-hour profiles of CTX, osteocalcin, and P1NP and to assess the 24-hour profiles of sclerostin and DKK1 in healthy older men and women and to compare these between men and women. We measured these five bone markers in EDTA plasma collected every 4 h during 24 h in 37 healthy older men and women (range 52-76 years). Differences between time points were determined using repeated measures ANOVA and cosinor analyses were performed to determine circadian rhythmicity. The circadian rhythm of CTX was confirmed by the cosinor model, with women showing larger amplitude compared to men. Osteocalcin showed higher levels during nighttime compared to daytime in both men and women. For P1NP levels we observed a small but significant increase in the night in men. Sclerostin and DKK1 did not show a circadian rhythm, but sclerostin levels differed between time points. Because of the large intraindividual variation, DKK1 as measured in this study cannot be considered a reliable marker for diagnostic or research purposes. In conclusion, when measuring CTX, osteocalcin, P1NP, or sclerostin either in clinical practice or in a research setting, one should consider the 24-hour profiles of these bone markers.

Bone Disease in Mastocytosis

Systemic mastocytosis can give very different bone pictures: from osteosclerosis to osteoporosis. Osteoporosis is one of the most frequent manifestations particularly in adults and the most clinical relevant. It is often complicated by a high recurrence of mainly vertebral fragility fractures. The main factor of bone loss is the osteoclast with a relative or absolute predominance of bone resorption. The RANK-RANKL pathway seems of key importance, but histamine and other cytokines also play a significant role in the process. The predominance of resorption made bisphosphonates, as anti-resorptive drugs, the most rational treatment of bone involvement in systemic mastocytosis.

Altered serum levels of type I collagen turnover indicators accompanied by IL-6 and IL-8 release in stable COPD

BACKGROUND

COPD, characterized by chronic inflammation and airway remodeling, has significant pathological alterations in composition and deposition of the extracellular matrix. The expression of procollagen 1 C-terminal peptide (PICP) and collagen type 1 C-terminal telopeptide (ICTP), two major by-products in the synthesis and degradation of collagen, was shown to be positively correlated with inflammatory mediator levels in previous studies.

PURPOSE

In this study, we investigated whether the serum concentrations of PICP and ICTP were associated with the inflammation level for patients with stable COPD.

PATIENTS AND METHODS

We collected serum samples from 25 control subjects and 20 patients with stable COPD from December 2011 to October 2012 in Shanghai Zhongshan Hospital and Shanghai Dahua Hospital. We determined concentrations of PICP, ICTP, C-reactive protein (CRP), IL-6, IL-8, and tumor necrosis factor (TNF)-α by using enzyme-linked immunosorbent assay methods.

RESULTS

Demographic characteristics were comparable between the two groups. In patients with stable COPD, serum levels of CRP, IL-6, IL-8, and TNF-α were all elevated compared to control subjects, but only changes of IL-6 achieved statistical significance. Serum concentration of PICP was significantly elevated in patients with COPD, and level of ICTP was slightly decreased. Moreover, serum concentrations of PICP were positively correlated with the levels of both IL-6 and IL-8.

CONCLUSION

The increased levels of serum PICP in COPD might indicate the condition of airway remodeling, and IL-6 and/or IL-8 might play an important role in stimulating collagen synthesis.

Regulatory effect of miR-421 on humeral fracture and heterotopic ossification in elderly patients

The present study aimed to investigate the role of miR-421 and bone morphogenetic protein-2 (BMP-2) in the bone tissues and blood of elderly patients with humeral fractures and heterotopic ossification. A total of 38 patients with humeral fractures, including 16 patients who received surgery within 1-7 days of fracture and 22 patients who received surgery within 8-14 days of fracture, were enrolled. An additional 18 patients who had heterotopic ossification and 26 patients who had humeral fracture and not heterotopic ossification were also included. Bone tissues and blood were collected. Reverse transcription-quantitative polymerase chain reaction was performed to determine the miR-421 and BMP-2 mRNA expression levels in the samples. Western blotting and ELISA were performed to detect BMP-2 protein levels in bone tissues and blood, respectively. Dual-luciferase reporter assays were performed to verify whether BMP-2 is the direct target gene of miR-421. Compared with the patients who received surgery 1-7 days after fracture, the patients who accepted the surgery 8-14 days after fracture had significantly increased levels of BMP-2 mRNA and protein in their bone tissues and blood (P<0.05). Contrastingly, the expression level of miR-421 decreased in the samples from patients who accepted the surgery 8-14 days after fracture compared with the level in those who received surgery 1-7 days after fracture (P<0.05). Compared with the patients without heterotopic ossification, the patients with heterotopic ossification had increased BMP-2 mRNA and protein expression levels in their bone tissues and blood, whereas the expression of miR-421 was significantly decreased (P<0.05). The dual-luciferase reporter assay demonstrated that BMP-2 was the direct target gene of miR-421. The upregulation of BMP-2 may be associated with the downregulation of miR-421. miR-421 may regulate the recovery of humeral fracture and heterotopic ossification through BMP-2. The results of the present study may provide a theoretical basis for the diagnosis and treatment of humeral fracture and heterotopic ossification.

Guidelines for the management of osteoporosis and fragility fractures

The purpose of this document, a result of the harmonisation and revision of Guidelines published separately by the SIMFER, SIOMMMS/SIR, and SIOT associations, is to provide practical indications based on specific levels of evidence and various grades of recommendations, drawn from available literature, for the management of osteoporosis and for the diagnosis, prevention, and treatment of fragility fractures. These indications were discussed and formally approved by the delegates of the Italian Scientific Associations involved in the project (SIE, SIGG, SIMFER, SIMG, SIMI, SIOMMMS, SIR, and SIOT).

Clinical advantages and disadvantages of anabolic bone therapies targeting the WNT pathway

The WNT signalling pathway is a key regulator of bone metabolism, particularly bone formation, which has helped to define the role of osteocytes - the most abundant bone cells - as orchestrators of bone remodelling. Several molecules involved in the control of the WNT signalling pathway have been identified as potential targets for the development of bone-building therapeutics for patients with osteoporosis. Several of these molecules have been investigated in animal models, but only inhibitors of sclerostin (which is produced by osteocytes) have been investigated in phase III clinical studies. Here, we review the rationale for these developments and the specificity and potential off-target actions of WNT-based therapeutics. We also describe the available preclinical and clinical studies and discuss the benefits and risks of using sclerostin inhibitors for the management of patients with osteoporosis.