Activity or mass concentration of bone-specific alkaline phosphatase as a marker of bone formation

Serum levels of bone turnover markers including calculation of Z-scores: Data from a Dutch healthy reference cohort

Introduction

Bone turnover markers (BTM) are biochemical compounds reflecting different stages of bone metabolism. Their levels change with age and differ between males and females. This makes clinical interpretation and comparison more difficult. Therefore, our aim was to establish BTM reference values which can be used to calculate Z-scores for use in daily clinical practice.

Methods

Serum markers of collagen resorption, bone formation/regulation, collagen formation and bone mineralization (sCTX, OC, PINP and BALP, respectively) were measured in non-fasting volunteers without bone-related abnormalities. Raw data was plotted and gender-specific age cohorts were established with their respective means and standard deviations (SD). Z-scores can be calculated using these reference values to correct for the influence of age and gender on BTM.

Results

In total, 856 individuals were included of which 486 (57 %) were female. Individuals were aged between 7 and 70 years. Highest serum levels of BTM were found in childhood and puberty. Peak levels are higher in boys than girls and prevail at later ages. In adults, BTM levels decrease before reaching stable nadir levels. In adults, 10-year reference cohorts with means and SD were provided to calculate Z-scores.

Conclusion

With our data, Z-scores of sCTX, OC, PINP and BALP can be calculated using reference categories (for age and gender) of Caucasian healthy volunteers. Clinicians can use BTM Z-scores to determine whether there are changes in bone turnover physiology beyond those expected during aging. BTM Z-scores facilitate harmonization of data interpretation in daily clinical practice and research.

Osteoporosis and the effect of dysregulation of the transsulfuration pathway via taurine on intracellular calcium homeostasis, vitamin D absorption and vitamin K absorption

BACKGROUND & AIMS

In this article we connect the dysregulation of the transsulfuration pathway to bone dysregulations and propose a novel treatment for osteoporosis. Current treatments for osteoporosis are very frequently inadequate. In osteoporosis, the risk of fractures increases with increased homocysteine (Hcy).

METHODS

Here, we conduct a review on the relationship between osteoporosis and the dysregulation of the transsulfuration pathway.

RESULTS

we show that the transsulfuration pathway metabolizes Hcy to L-cysteine. Increased Hcy levels point to the transsulfuration pathway being dysregulated. With the transsulfuration pathway dysregulated, there will be decreased levels of L-cysteine and decreased levels of taurine, which is synthesized from L-cysteine. Taurine levels are decreased in patients with osteoporosis. Taurine regulates intracellular calcium homeostasis. Taurine, also, when conjugated with bile acids assists with absorption of fats and fat-soluble vitamins such as vitamin D and vitamin K. Dysregulated calcium homeostasis, decreased calcium absorption and decreased absorption of vitamin D and vitamin K due to low levels of taurine negatively affect bone mineral density (BMD) leading to osteoporosis and fractures.

CONCLUSIONS

In this article, we propose that a combination of taurine, calcium, vitamin D and vitamin K, could increase BMD reducing number of years spent in disability and reducing deaths due to fractures in patients with osteoporosis.

Association between serum osteocalcin and glucose/lipid metabolism in Chinese Han and Uygur populations with type 2 diabetes mellitus in Xinjiang: two cross-sectional studies

Background

Recent studies have shown osteocalcin (OC) plays an important role in regulating glucose and lipid metabolism. Thus, the aim of this study was to investigate the association of OC with glucose and lipid metabolism in patients with type 2 diabetes mellitus (T2DM) in the Chinese Han and Uygur population.

Methods

A total of 1397 T2DM patients (705 Han and 692 Uygur T2DM patients) were enrolled in the present study. Lipid profile, glucose metabolic indices and total OC (TOC) were measured. Homeostasis model assessment of β-cells function (HOMA-β), insulin sensitivity (HOMA-IS) and insulin resistance (HOMA-IR) were also calculated in all participants. Pearson/Spearman correlation analysis and multivariate stepwise regression analysis were adopted to test the relationships between OC and those parameters.

Results

Uygur T2DM patients had significantly higher body mass index (BMI), hemoglobin A1C (HbA1C) and lower TOC compared with their Han counterparts (all P < 0.05). HbA1C was negatively associated with TOC in all Uygur and Han T2DM patients (Total: Uygur: t = −3.468, P = 0.001; Han: t = −4.169, P < 0.001). BMI was inversely associated with TOC in all Uygur T2DM patients (Males: t = −2.893, P = 0.014; Females: t = −2.250, P = 0.027, respectively). Multivariate stepwise regression analysis showed that TOC was positively correlated with HOMA-β in the Uygur male group (β = 2.101, P = 0.040) and negatively associated with BMI in all Uygur T2DM patients (Males: β = −1.563, P = 0.011; Females: β = −1.284, P = 0.016, respectively). No significant differences were observed between TOC and lipid profiles in all participants (all P > 0.05).

Conclusion

There were differences in the associations between TOC and glucose metabolism in Han and Uygur T2DM patients, indicating genetic factors may play a role in modulating OC and glucose metabolism in different ethnic population.

Vitamin D Deficiency Is Associated with Increased Osteocalcin Levels in Acute Aortic Dissection: A Pilot Study on Elderly Patients

An imbalance between degradation and reconstruction of the aortic wall is one of the leading causes of acute aortic dissection (AAD). Vitamin D seems an intriguing molecule to explore in the field of AAD since it improves endothelial function and protects smooth muscle cells from inflammation-induced remodeling, calcification, and loss of function, all events which are strongly related to the aging process. We quantified 25-hydroxy vitamin D, calcium, parathormone, bone alkaline phosphatase, and osteocalcin levels in 24 elderly AAD patients to identify a potential pathological implication of these molecules in AAD. Median 25-hydroxy vitamin D (10.75 ng/mL, 25th–75th percentiles: 6.86–19.23 ng/mL) and calcium levels (8.70 mg/dL, 25th–75th percentiles: 7.30–8.80 mg/dL) suggested hypovitaminosis D and a moderate hypocalcemia. Thirty-eight percent of AAD patients had severe (<10 ng/mL), 38% moderate (10–20 ng/mL), and 24% mild 25-hydroxy vitamin D deficiency (20–30 ng/mL). A significant inverse correlation was observed between 25OHD and osteocalcin levels. All the other molecules were unchanged. A condition of hypovitaminosis D associated to an increase in osteocalcin levels is present in AAD patients. The identification of these molecules as new factors involved in AAD may be helpful to identify individuals at high risk as well to study preventing strategies.

Effects on bone metabolism markers and arterial stiffness by switching to rivaroxaban from warfarin in patients with atrial fibrillation

In recent years, direct oral anticoagulants (DOACs) of dabigatran, rivaroxaban, apixaban, edoxaban, which are all alternatives to warfarin, have been released. The use of DOACs is becoming more widespread in the clinical management of thrombotic stroke risk in patients with atrial fibrillation (AF). In large-scale clinical trials of each drug, DOACs were reported to inhibit intracranial hemorrhage, stroke, and death compared to warfarin. Warfarin is an endogenous vitamin K antagonist; therefore, patients who are taking warfarin must be prohibited from taking vitamin K. Vitamin K is an essential cofactor required for the ɤ-carboxylation of vitamin K-dependent proteins including coagulation factors, osteocalcin (OC), matrix Gla protein (MGP), and the growth arrest-specific 6 (GAS6). OC is a key factor for bone matrix formation. MGP is a local inhibitor of soft tissue calcification in the vessel wall. GAS6 prevents the apoptosis of vascular smooth muscle cells. Therefore, decrease of blood vitamin K levels may cause osteoporosis, vascular calcification, and the inhibition of vessels angiogenesis. This study aimed to evaluate the effects of changing from warfarin to rivaroxaban on bone mineral metabolism, vascular calcification, and vascular endothelial dysfunction. We studied 21 consecutive patients with persistent or chronic AF, who were treated with warfarin at least for 12 months. Warfarin administration was changed to rivaroxaban (10 or 15 mg/day) in all patients. Osteopontin (OPN), bone alkaline phosphatase (BAP), and under-carboxylated osteocalcin (ucOC) were measured. Pulse wave velocity (PWV) and augmentation index (AI) were also measured as atherosclerosis assessments. All measurements were done before and six months after the rivaroxaban treatment. There was a significant increase in serum level of BAP compared to baseline (12.5 ± 4.6 to 13.4 ± 4.1 U/L, P < 0.01). In contrast, there was a significant decrease in the serum level of ucOC (9.5 ± 5.0 to 2.7 ± 1.3 ng/ml, P < 0.01). Also, in the ucOC levels, there was a significant negative correlation between baseline values and baseline to 6-months changes in high ucOC group (r = -0.97, P < 0.01). The atherosclerosis- and osteoporosis-related biomarker, serum level of OPN were significantly decreased compared to baseline (268.3 ± 46.8 to 253.4 ± 47.1 ng/ml, P < 0.01). AI and PWV were significantly decreased after 6 months of treatment with rivaroxaban (33.9 ± 18.4 to 24.7 ± 18.4%, P = 0.04; 1638.8 ± 223.0 to 1613.0 ± 250.1 m/s, P = 0.03, respectively). Switching to rivaroxaban from warfarin in patients with atrial fibrillation was associated with an increase of bone formation markers and a decrease of bone resorption markers, and also improvements of PWV and AI.

Extracorporeal Shockwave Therapy Enhances Expression of Pdia-3 Which Is a Key Factor of the 1α,25-Dihydroxyvitamin D 3 Rapid Membrane Signaling Pathway in Treatment of Early Osteoarthritis of the Knee

The goal of our research was demonstrated that multiple molecules in microenvironments of the early osteoarthritis (OA) joint tissue may be actively responded to extracorporeal shockwave therapy (ESWT) treatment, which potentially regulated biological function of chondrocytes and synovial cells in early OA knee. We demonstrated that shockwave treatment induced the expression of protein-disulfide isomerase-associated 3 (Pdia-3) which was a significant mediator of the 1α,25-Dihydroxyvitamin D 3 (1α,25(OH)2D3) rapid signaling pathway, using two-dimensional electrophoresis, histological analysis and quantitative polymerase chain reaction (qPCR). We observed that the expression of Pdia-3 at 2 weeks was significantly higher than that of other group at 4, 8, and 12 weeks post-shockwave treatment in early OA rat knee model. The other factors of the rapid membrane signaling pathway, including extracellular signal-regulated protein kinases 1 (ERK1), osteopontin (OPG), alkaline phosphatase (ALP), and matrix metallopeptidase 13 (MMP13) were examined and were found to be significantly increased at 2 weeks post-shockwave treatment by qPCR in early OA of the knee. Our proteomic data revealed significant Pdia-3 expression in microenvironments of OA joint tissue that could be actively responded to ESWT, which may potentially regulate the biological functions of chondrocytes and osteoblasts in the treatment of the early OA of the knee.

Direct effects of physical training on markers of bone metabolism and serum sclerostin concentrations in older adults with low bone mass

Background

Both gravitational loading and the forces generated by muscle contraction have direct effects on serum markers of bone metabolism. The object of this study was to examine the direct effects of a single session of resistance exercise or walking on biochemical markers of bone metabolism in participants with low bone mass.

Methods

A total of 150 otherwise healthy female subjects (mean age = 59.1 ± 7.1 years) diagnosed with osteoporosis or osteopenia were randomly allocated to either a resistance exercise group (RG; n = 50), walking group (WG; n = 50), or control group (CG; n = 50). Changes in bone-specific alkaline phosphatase (BALP), carboxy-terminal cross-linked telopeptide of type I collagen (CTX), and serum sclerostin concentrations were measured before and immediately after a single exercise intervention.

Results

There was no significant change in BALP values in any of the groups. Sclerostin levels increased in the RG and WG, and there was significant difference between the WG and CG after the exercise intervention (P < 0.01). In contrast, the changes in CTX concentrations from baseline were significant in the RG (P < 0.01) but not in the WG (P = 0.11), and there was a significant difference between resistance exercise and walking (P < 0.01).

Conclusions

In participants with low bone mass, resistance exercise influenced the serum concentrations of CTX, a marker of bone resorption, but walking did not.

Trial registration

Current Controlled Trials ISRCTN16329455; retrospectively registered on 05/05/2016.

Joint dysfunction and functional decline in middle age myostatin null mice

Since its discovery as a potent inhibitor for muscle development, myostatin has been actively pursued as a drug target for age- and disease-related muscle loss. However, potential adverse effects of long-term myostatin deficiency have not been thoroughly investigated. We report herein that male myostatin null mice (mstn(-/-)), in spite of their greater muscle mass compared to wild-type (wt) mice, displayed more significant functional decline from young (3-6months) to middle age (12-15months) than age-matched wt mice, measured as gripping strength and treadmill endurance. Mstn(-/-) mice displayed markedly restricted ankle mobility and degenerative changes of the ankle joints, including disorganization of bone, tendon and peri-articular connective tissue, as well as synovial thickening with inflammatory cell infiltration. Messenger RNA expression of several pro-osteogenic genes was higher in the Achilles tendon-bone insertion in mstn(-/-) mice than wt mice, even at the neonatal age. At middle age, higher plasma concentrations of growth factors characteristic of excessive bone remodeling were found in mstn(-/-) mice than wt controls. These data collectively indicate that myostatin may play an important role in maintaining ankle and wrist joint health, possibly through negative regulation of the pro-osteogenic WNT/BMP pathway.

Effective delivery of bone morphogenetic protein 2 gene using chitosan–polyethylenimine nanoparticle to promote bone formation

Treating bone defects is still a challenge in clinical practice.

Differential effects of adiponectin in osteoblast-like cells

The skeleton should maintain an adequate volume, vigour and strength to carry out the role for which it is designed: to hold the whole soft tissue mass that shapes the body and to protect the vital organs. To fulfil this task a satisfactory food intake is required and regulators that are released in the feeding and fasting states, among other signals indicate how much soft mass needs to be built up. Those signals include the secretion of adipocytokines which could represent a relevant link between soft mass (adipose tissue) and skeleton. We studied the presence of adiponectin receptors (AdipoR1, AdipoR2) and its direct effects in osteosarcoma cell line Saos-2. The results indicated that adiponectin receptors were present in the osteoblastic cells with a higher expression of AdipoR1. Human recombinant globular adiponectin was able to increase viability levels and decrease cytotoxicity rates in cell cultures. Also, adiponectin significantly inhibited alkaline phosphatase activity in supernatants. Osteoprotegerin mRNA expression was significantly reduced after 72 h treatment. The FOS induction was studied and the results exhibited a significant increase caused by adiponectin. In conclusion, all these observations suggest that adiponectin influences bone metabolism decreasing the levels of bone formation. Regulators of adiponectin or its receptors could be circulating to modulate the activities of this peptide.

Deficiency in androgens and upregulation of insulin-like growth factor-1 are involved in high bone turnover in men receiving androgen deprivation therapy for prostate cancer

OBJECTIVE

This study was performed to elucidate the mechanism of high bone turnover during androgen deprivation therapy (ADT) in terms of osteogenic endocrine activity by testosterone, adrenal androgens, and insulin-like growth factor-1 (IGF-I), and to identify markers reflecting the bone mineral density (BMD) during ADT.

DESIGN

BMD and samples of blood and urine were studied before and after 6months of ADT in 70 patients with localized prostate cancer.

RESULTS

Before ADT, serum free-testosterone, dehydroepiandrosterone sulfate (DHEA-S), androstenedione, and IGF-I levels were correlated with BMD (rs=0.344, p=0.004; rs=0.264, p=0.027; rs=0.329, p=0.005; rs=0.300, p=0.012, respectively). The serum IGF-I level was independently correlated with the pretreatment BMD (Multivariate p=0.001). These relationships disappeared after ADT (p=0.519, 0.316, 0.116, and 0.597, respectively). After ADT, serum levels of free-testosterone decreased (7.9 to 0.2pg/mL), and DHEA-S and androstenedione were also reduced (3.6 to 2.3μmol/L and 5.6 to 2.9nmol/L, respectively) (p<0.001 in all). In contrast, IGF-I levels were elevated after ADT by 11.6% (19.9 to 22.3nmol/L, p<0.001). Delta-values of IGF-I (post- minus pretreatment levels, mean: +2.2, ranged between -7.1 and +15.3) were inversely correlated with the pretreatment (rs=-0.333 p=0.005) and post-treatment (rs=-0.408, p=0.001) BMD. After ADT, the serum IGF-I level was closely correlated with the serum level of the bone formation marker bone-specific alkaline phosphatase (BAP) (rs=0.328, p=0.006), and delta-IGF-I and delta-BAP showed a close positive correlation (rs=0.388, p=0.001). The post-treatment BMD was correlated only with the urine deoxypyridinoline (DPD) concentration (rs=-0.302, p=0.024) among the bone formation/resorption markers including serum/urine N-telopeptide.

CONCLUSIONS

Serum IGF-I levels increased during ADT in men with a low BMD. Coupled with reduced androgen levels, elevated IGF-I levels, which were positively correlated with BAP during ADT, possibly explain the mechanism of ADT-related high bone turnover. The increase of IGF-I is more prominent in men whose BMD is already low at the baseline, and urine DPD might be a marker that reflects BMD during ADT.

New mouse models for metabolic bone diseases generated by genome-wide ENU mutagenesis

Metabolic bone disorders arise as primary diseases or may be secondary due to a multitude of organ malfunctions. Animal models are required to understand the molecular mechanisms responsible for the imbalances of bone metabolism in disturbed bone mineralization diseases. Here we present the isolation of mutant mouse models for metabolic bone diseases by phenotyping blood parameters that target bone turnover within the large-scale genome-wide Munich ENU Mutagenesis Project. A screening panel of three clinical parameters, also commonly used as biochemical markers in patients with metabolic bone diseases, was chosen. Total alkaline phosphatase activity and total calcium and inorganic phosphate levels in plasma samples of F1 offspring produced from ENU-mutagenized C3HeB/FeJ male mice were measured. Screening of 9,540 mice led to the identification of 257 phenodeviants of which 190 were tested by genetic confirmation crosses. Seventy-one new dominant mutant lines showing alterations of at least one of the biochemical parameters of interest were confirmed. Fifteen mutations among three genes (Phex, Casr, and Alpl) have been identified by positional-candidate gene approaches and one mutation of the Asgr1 gene, which was identified by next-generation sequencing. All new mutant mouse lines are offered as a resource for the scientific community.

Physical training increases osteoprotegerin in postmenopausal women

The purpose of this study was to explore whether mechanical loading by exercise over a 1-year period in postmenopausal women had an effect on the receptor activator for nuclear factor kappa B ligand/osteoprotegerin (RANKL/OPG) system or the levels of the Wnt-signaling antagonist sclerostin. A total of 112 postmenopausal were randomized to either sedentary life (controls) or physical activity (training group). Ninety-two women fulfilled the study protocol. The training program consisted of three fast 30-min walks and one or two 1-h aerobic training sessions per week. The effect on the bone mineral density of the hip assessed with dual X-ray absorptiometry was positive as reported earlier. Blood samples were taken from participants at baseline and after 1 year and serum levels of OPG, RANKL and sclerostin were quantified together with the bone metabolism markers C-terminal telopeptide of collagen type I (CTX) and bone-specific alkaline phosphatase (BALP). The results were analyzed using an analysis of covariance model using baseline values as the covariate. The training group displayed a clear mean increase of OPG +7.55 pg/ml compared to controls (p = 0.007). The mean changes for RANKL +0.19 pg/ml (square-root transformed data) and sclerostin +0.62 pmol/l were non-significant (p = 0.13 and p = 0.34). The changes in bone turnover markers CTX and BALP showed a tendency to decrease in the training group versus controls but the changes were small and non-significant. Although our study is limited in number of participating women, we have been able to show an OPG-associated, and RANKL- and sclerostin-independent, training-induced inhibition of postmenopausal bone loss.

5-Azacytidine facilitates osteogenic gene expression and differentiation of mesenchymal stem cells by alteration in DNA methylation

Mesenchymal stem cells (MSCs) are considered to be one of the most promising therapeutic cell sources as they encompass a plasticity of multiple cell lineages. The challenge in using these cells lies in developing well-defined protocols for directing cellular differentiation to generate a desired lineage. In this study, we investigated the effect of 5-azacytidine, a DNA demethylating agent, on osteogenic differentiation of MSCs. The cells were exposed to 5-azacytidine in culture medium for 24 h prior to osteogenic induction. Osteogenic differentiation was determined by several the appearance of a number of osteogenesis characteristics, including gene expression, ALP activity, and calcium mineralization. Pretreatment of MSCs with 5-azacytidine significantly facilitated osteogenic differentiation and was accompanied by hypomethylation of genomic DNA and increased osteogenic gene expression. Taking dlx5 as a representative, methylation alterations of the "CpG island shore" in the promoter caused by 5-azacytidine appeared to contribute to osteogenic differentiation.

Effects of short-term risedronate on bone resorption and patient satisfaction in postmenopausal osteoporosis patients

This multicenter, open-label study evaluated the effects of short-term risedronate on bone resorption and patient satisfaction in postmenopausal women with osteoporosis in Brazil. Entry requirements included: osteoporosis of the spine/femoral neck diagnosed by a bone mineral density (BMD) T-score<or=-2.5 or radiographic fragility fracture within the last year and no treatment with osteoporosis medication in the preceding 3 mo. Patients were treated with once weekly risedronate of 35 mg for 12 wk. Patients also received 1000 mg calcium carbonate and 400 IU vitamin D. The main outcome was the effect on bone resorption, as assessed by the quantification of serum C-telopeptide of type I collagen (CTX). Of the 556 women screened, 480 women received >or=1 dose of study drug (intent-to-treat [ITT] population), and 390 completed treatment (81%). After 12 wk, CTX decreased in 94% of patients (from 0.419+/-0.234 to 0.158+/-0.171 microg/L, p<0.0001). Mean CTX reduction was 60.6%. Patient satisfaction was good/excellent in 91.7% of patients. A total of 156 adverse events (AEs) were reported by 113 (23.5%) patients in the ITT population. Digestive symptoms emerged or worsened in 7.1% and 3.5%, respectively. Five patients (1.0%) experienced serious AEs, not considered to be related to risedronate. In conclusion, risedronate significantly reduced serum CTX after 12-wk treatment. Almost all patients reported good/excellent satisfaction.