Serum levels of TRAP5b, a new bone resorption marker unaffected by renal dysfunction, as a useful marker of cortical bone loss in hemodialysis patients

Associations of Changes in Bone Turnover Markers with Change in Bone Mineral Density in Kidney Transplant Patients

BACKGROUND

Bone loss after kidney transplantation is highly variable. We investigated whether changes in bone turnover markers associate with bone loss during the first post-transplant year.

METHODS

Bone mineral density (BMD) was measured at 0 and 12 months, with biointact parathyroid hormone, bone-specific alkaline phosphatase (BALP), intact procollagen type I N -terminal propeptide (PINP), and tartrate-resistant acid phosphatase isoform 5b (TRAP5b) measured at 0, 3, and 12 months post-transplant ( N =209). Paired transiliac bone biopsies were available in a subset ( n =49). Between-group differences were evaluated by Student's t test, Wilcoxon signed-rank test, or Pearson's chi-squared test.

RESULTS

Changes in BMD varied from -22% to +17%/yr. Compared with patients with no change (±2.5%/yr), patients who gained BMD had higher levels of parathyroid hormone (236 versus 136 pg/ml), BALP (31.7 versus 18.8 μ g/L), and Intact PINP (121.9 versus 70.4 μ g/L) at time of transplantation; a greater decrease in BALP (-40% versus -21%) and Intact PINP (-43% versus -13%) by 3 months; and lower levels of Intact PINP (36.3 versus 60.0 μ g/L) at 12 months post-transplant. Patients who lost BMD had a less marked decrease, or even increase, in Intact PINP (+22% versus -13%) and TRAP5b (-27% versus -43%) at 3 months and higher Intact PINP (83.7 versus 60.0 μ g/L) and TRAP5b (3.89 versus 3.16 U/L) at 12 months compared with patients with no change. If none of the biomarkers decreased by the least significant change at 3 months, an almost two-fold (69% versus 36%) higher occurrence of bone loss was seen at 12 months post-transplant.

CONCLUSIONS

Bone loss after kidney transplantation was highly variable. Resolution of high bone turnover, as reflected by decreasing bone turnover markers, associated with BMD gain, while increasing bone turnover markers associated with bone loss.

Molecularly Imprinted Polymers: Shaping the Future of Early-Stage Bone Loss Detection-A Review

Osteoporosis is the deterioration of bone mineral density (BMD) because of an imbalance between bone resorption and formation, which might happen due to lots of factors like age, hormonal imbalance, and several others. While this occurrence is prevalent in both genders, it is more common in women, especially postmenopausal women. It is an asymptomatic disease that is underlying until the first incidence of a fracture. The bone is weakened, making it more susceptible to fracture. Even a low trauma can result in a fracture, making osteoporosis an even more alarming disease. These fractures can sometimes be fatal or can make the patient bedridden. Osteoporosis is an understudied disease, and there are certain limitations in diagnosing and early-stage detection of this condition. The standard method of dual X-ray absorptiometry can be used to some extent and can be detected in standard radiographs after the deterioration of a significant amount of bone mass. Clinically assessing osteoporosis using biomarkers can still be challenging, as clinical tests can be expensive and cannot be accessed by most of the general population. In addition, manufacturing antibodies specific to these biomarkers can be a challenging, time-consuming, and expensive method. As an alternative to these antibodies, molecularly imprinted polymers (MIPs) can be used in the detection of these biomarkers. This Review provides a comprehensive exploration of bone formation, resorption, and remodeling processes, linking them to the pathophysiology of osteoporosis. It details biomarker-based detection and diagnosis methods, with a focus on MIPs for sensing CTX-1, NTX-1, and other biomarkers. The discussion compares traditional clinical practices with MIP-based sensors, revealing comparable sensitivity with identified limitations. Additionally, the Review contrasts antibody-functionalized sensors with MIPs. Finally, our Review concludes by highlighting the potential of MIPs in future early-stage osteoporosis detection.

Real-world usage of Chronic Kidney Disease - Mineral Bone Disorder (CKD-MBD) biomarkers in nephrology practices

Background

Chronic kidney disease mineral bone disorder (CKD-MBD) is a condition characterized by alterations of calcium, phosphate, parathyroid hormone (PTH), and fibroblast growth factor 23 (FGF-23) metabolism that in turn promote bone disorders, vascular calcifications, and increase cardiovascular (CV) risk. Nephrologists' awareness of diagnostic, prognostic, and therapeutic tools to manage CKD-MBD plays a primary role in adequately preventing and managing this condition in clinical practice.

Methods

A national survey (composed of 15 closed questions) was launched to inquire about the use of bone biomarkers in the management of CKD-MBD patients by nephrologists and to gain knowledge about the implementation of guideline recommendations in clinical practice.

Results

One hundred and six Italian nephrologists participated in the survey for an overall response rate of about 10%. Nephrologists indicated that the laboratories of their hospitals were able to satisfy request of ionized calcium levels, 105 (99.1%) of both PTH and alkaline phosphatase (ALP), 100 (94.3%) of 25(OH)D, and 61 (57.5%) of 1.25(OH)2D; while most laboratories did not support the requests of biomarkers such as FGF-23 (intact: 88.7% and c-terminal: 93.4%), Klotho (95.3%; soluble form: 97.2%), tartrate-resistant acid phosphatase 5b (TRAP-5b) (92.5%), C-terminal telopeptide (CTX) (71.7%), and pro-collagen type 1 N-terminal pro-peptide (P1NP) (88.7%). As interesting data regarding Italian nephrologists' behavior to start treatment of secondary hyperparathyroidism (sHPT), the majority of clinicians used KDOQI guidelines (n = 55, 51.9%). In contrast, only 40 nephrologists (37.7%) relied on KDIGO guidelines, which recommended referring to values of PTH between two and nine times the upper limit of the normal range.

Conclusion

Results point out a marked heterogeneity in the management of CKD-MBD by clinicians as well as a suboptimal implementation of guidelines in Italian clinical practice.

An aqueous extract of Prunella vulgaris L. ameliorates cadmium-induced bone loss by promoting osteogenic differentiation in female rats

Cadmium (Cd) causes bone loss, concerning inhibiting osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Prunella vulgaris L. (PV) has the potential for promoting osteogenic differentiation, but its influence on Cd-induced bone loss is unclear. This study investigated the effect of PV aqueous extract (PVE) on Cd-induced bone loss and its underlying mechanisms. Eight-week-old female SD rats were randomly assigned into four groups and treated for 16 weeks: Control, Cd (50 mg/L of Cd chloride), Cd + PV Low (125 mg/kg bw of PVE), and Cd + PV High (250 mg/kg bw of PVE). PV ameliorated femoral bone loss in Cd-treated rats manifested as increases in bone mineral density, bone volume, trabecular thickness, number, and area, and decreases in trabecular separation. Compared with Cd group, PV-treatment groups had higher serum levels of bone formation markers (ALP, BGP). Additionally, in PV-treatment groups, expressions of bone formation markers (Osterix, Runx2) and molecules involved in osteogenic differentiation signal pathway BMP/Smad (BMP4, Smad1/5/9) in the tibia of rats and isolated rat primary BMSCs were upregulated. These results suggest that PV alleviates Cd-induced bone loss by promoting osteogenic differentiation, which is likely associated with BMP/Smad pathway.

Practical Considerations for the Clinical Application of Bone Turnover Markers in Osteoporosis

Bone turnover markers (BTMs) are released during the bone remodelling cycle and are measurable in blood or urine, reflecting bone remodelling rate. They have been useful in elucidating the pharmacodynamics and effectiveness of osteoporosis medication in clinical trials and are increasingly used in routine clinical management of osteoporosis, especially for monitoring therapy, in addition to their use in other metabolic bone disease such as Paget's disease of bone and osteomalacia. Serum β isomerised C-terminal telopeptide of type I collagen and pro-collagen I N-terminal propeptide have been designated as reference BTMs for use in osteoporosis. In addition, bone-specific isoenzyme of alkaline phosphatase (B-ALP) secreted by osteoblasts and tartrate-resistant acid phosphatase 5b (TRACP-5b) secreted by osteoclasts are also found to be specific markers of bone formation and resorption, respectively. The concentrations of the latter enzymes in blood measured by immunoassay provide reliable measures of bone turnover even in the presence of renal failure. B-ALP is recommended for use in the assessment of renal bone disease of chronic kidney disease, and TRACP-5b shows promise as a marker of bone resorption in that condition. BTMs in blood do not suffer from biological variation to the same extent as the older BTMs that were measured in urine. Appropriate patient preparation and sample handling are important in obtaining accurate measures of BTMs for clinical use. Reference change values and treatment targets have been determined for the reference BTMs for their use in monitoring osteoporosis treatment. Further ongoing studies will enhance their clinical applications.

Bone Turnover Markers in Children: From Laboratory Challenges to Clinical Interpretation

Bone turnover markers (BTMs) have been developed many years ago to study, in combination with imaging techniques, bone remodeling in adults. In children and adolescents, bone metabolism differs from adults since it implies both growth and bone remodeling, suggesting an age- and gender-dependent BTM concentration. Therefore, specific studies have evaluated BTMs in not only physiological but also pathological conditions. However, in pediatrics, the use of BTMs in clinical practice is still limited due to these many children-related specificities. This review will discuss about physiological levels of BTMs as well as their modifications under pathological conditions in children and adolescents. A focus is also given on analytical and clinical challenges that restrain BTM usefulness in pediatrics.

Diagnostic and prognostic significance of tartrate-resistant acid phosphatase type 5b in newly diagnosed prostate cancer with bone metastasis: A real-world multi-institutional study

OBJECTIVES

Approximately, 90% of men with advanced prostate cancer will develop bone metastasis. However, there have been few reports about noninvasive biomarker to detect and predict clinical outcome of bone metastasis (BM) in prostate cancer patients.

METHODS

We examined 1127 patients who underwent prostate biopsy from August 2012 to June 2017. We also investigated bone turnover markers such as bone-specific alkaline phosphatase, type I collagen cross-linked N-terminal telopeptide, C-terminal pyridinoline cross-linked telopeptide of type I collagen, and tartrate-resistant acid phosphatase type 5b (TRACP 5b).

RESULTS

A total of 282 patients were diagnosed as prostate cancer with complete clinical data, and 34 patients with bone metastasis. Multivariate analysis revealed C-terminal pyridinoline cross-linked telopeptide of type I collagen, tartrate-resistant acid phosphatase type 5b, and prostate-specific antigen (PSA) were independent biomarkers in detection of BM (p < 0.05, respectively). Furthermore, we developed predictive model formula based on tartrate-resistant acid phosphatase type 5b and PSA, for which the area under the curve was 0.95. In patients with bone metastasis, multivariate cox proportional hazards analysis revealed that this model was significantly associated with poor clinical outcome of cancer-specific survival (p < 0.05). In validation cohort with 137 patients, we also confirmed the utility of this model for diagnosis of BM (the area under the curve = 0.95).

CONCLUSIONS

Our developed formula of tartrate-resistant acid phosphatase type 5b in accordance with PSA may serve as the useful tool in diagnosis and prediction of clinical outcome for prostate cancer with bone metastasis.

One-Year Romosozumab Treatment Followed by One-Year Denosumab Treatment for Osteoporosis in Patients on Hemodialysis: An Observational Study

There is limited evidence on the use of romosozumab (ROMO) in the treatment of osteoporosis in patients on hemodialysis (HD); thus, we aimed to investigate this topic. This prospective, observational, single-center cohort study included 13 prior osteoporosis treatment-naïve patients on HD with osteoporosis. They first received ROMO once monthly for 12 months (210 mg; subcutaneously once every month). Thereafter, they received denosumab (DENO) for an additional 12 months (60 mg; subcutaneously once every 6 months). We examined the incidence of new fractures; treatment safety; and temporal changes in the bone mineral density (BMD), bone metabolism markers, and vascular calcification. No new cases of fractures were noted. The median one-year percentage changes (from the baseline) in the BMDs at the lumbar spine (LS), total hip (TH), and femoral neck (FN) were + 9.0%, + 2.5%, and + 4.7%, respectively. These changes were maintained for 24 months. The corresponding relative changes from the baseline to 24 months thereafter were + 14.9%, + 5.4%, and + 6.5%, respectively. The percentage changes in TH BMD and FN BMD were negatively correlated with baseline BMD. Coronary artery and thoracic aorta calcification scores increased slightly from baseline to 12 months thereafter. However, fatal events (cardiovascular disease-associated and all-cause deaths) did not occur during ROMO treatment. Effectiveness of ROMO was better in patients who had severe osteoporosis with low TH BMD, low FN BMD, and high tartrate-resistant acid phosphatase 5b level at ROMO initiation.

Is Adynamic Bone Always a Disease? Lessons from Patients with Chronic Kidney Disease

Renal osteodystrophy (ROD) is a common complication of end-stage kidney disease that often starts early with loss of kidney function, and it is considered an integral part in management of patients with chronic kidney disease (CKD). Adynamic bone (ADB) is characterized by suppressed bone formation, low cellularity, and thin osteoid seams. There is accumulating evidence supporting increasing prevalence of ADB, particularly in early CKD. Contemporarily, it is not very clear whether it represents a true disease, an adaptive mechanism to prevent bone resorption, or just a transitional stage. Several co-players are incriminated in its pathogenesis, such as age, diabetes mellitus, malnutrition, uremic milieu, and iatrogenic factors. In the present review, we will discuss the up-to-date knowledge of the ADB and focus on its impact on bone health, fracture risk, vascular calcification, and long-term survival. Moreover, we will emphasize the proper preventive and management strategies of ADB that are pivotal issues in managing patients with CKD. It is still unclear whether ADB is always a pathologic condition or whether it can represent an adaptive process to suppress bone resorption and further bone loss. In this article, we tried to discuss this hard topic based on the available limited information in patients with CKD. More studies are needed to be able to clearly address this frequent ROD finding.

Lower Bone Turnover and Skeletal PTH Responsiveness in Japanese Compared to European Patients on Hemodialysis

CONTEXT

Parathyroid hormone (PTH) treatment targets for patients receiving hemodialysis (HD) are lower in Japan than in Europe. Whether this translates to lower bone turnover is unknown and could depend on skeletal PTH responsiveness.

OBJECTIVE

This study investigates whether skeletal PTH responsiveness is better preserved in Japanese vs European patients receiving HD.

METHODS

This is a post hoc analysis of data from 2 prospective cohort studies, using a case-control design. Patients receiving chronic intermittent HD therapy were eligible for inclusion. Participating Belgian and Japanese patients (n = 374) were matched 1:1 by age (59 ± 12 years), sex (66% male), diabetes (34%), and dialysis duration (39 months [22-63 months]). PTH, bone-specific alkaline phosphatase (BALP), and tartrate-resistant acid phosphatase isoform 5b (TRAP5b) were measured centrally in Liège, Belgium.

RESULTS

Japanese patients had lower levels of iPTH (207 vs 268 pg/mL; P < .001), BALP (15.3 vs 24.5 μg/L; P < .001), and TRAP5b (3.35 vs 5.79 U/L; P < .001). Linear regression analyses revealed lower levels of bone turnover markers for any given level of PTH in Japanese vs Belgian patients, indicating lower skeletal PTH responsiveness. Consistently, bone turnover markers were significantly lower in Japanese vs Belgian patients when stratifying or matching according to PTH levels. Male sex, obesity, and hyperphosphatemia were the main determinants of the bone turnover marker/PTH ratios.

CONCLUSION

Japanese patients receiving HD have lower bone turnover than their European counterparts, even at similar PTH levels. The rationale for the current regional differences in PTH treatment targets remains obscure and deserves further attention.

Evaluation of optimal dietary calcium level by bone characteristics and calcium metabolism-related gene expression of broilers from 22 to 42 d of age

The current dietary Ca recommendation of broilers is primarily based on the previous studies carried out more than 30 yr ago. However, the modern commercial broilers are quite different from those more than 30 yr ago. The present experiment was conducted to evaluate an optimal dietary Ca level by bone characteristics and Ca metabolism-related gene expression of broilers fed a corn-soybean meal diet from 22 to 42 d of age. A total of 252 22-d-old Arbor Acres male broilers were randomly assigned to 1 of 7 treatments with 6 replicate cages of 6 birds per cage for each treatment. Broilers were fed the corn-soybean meal diets containing 0.50%, 0.60%, 0.70%, 0.80%, 0.90%, 1.00%, or 1.10% Ca for 21 d, and each diet contained 0.31% non-phytate P. The results showed that the mineral contents in tibia and middle toe bone, mineral density in tibia and middle toe bone, middle toe ash percentage, middle toe ash Ca percentage, and tibia alkaline phosphatase mRNA expression level of broilers were influenced (P < 0.04) by dietary Ca level and increased quadratically (P < 0.05) as dietary Ca level increased. The estimates of optimal dietary Ca levels were 0.55%, 0.60%, 0.70%, 0.72%, 0.63%, 0.66%, and 0.70%, respectively, based on the best fitted broken-line, quadratic, or asymptotic models (P < 0.02) of the above sensitive indices. These results indicate that the optimal dietary Ca level would be 0.72% to support all of the Ca metabolism and bone development of broilers fed the corn-soybean meal diet from 22 to 42 d of age.

Advances in the Progression and Prognosis Biomarkers of Chronic Kidney Disease

Chronic kidney disease (CKD) is one of the increasingly serious public health concerns worldwide; the global burden of CKD is increasingly due to high morbidity and mortality. At present, there are three key problems in the clinical treatment and management of CKD. First, the current diagnostic indicators, such as proteinuria and serum creatinine, are greatly interfered by the physiological conditions of patients, and the changes in the indicator level are not synchronized with renal damage. Second, the established diagnosis of suspected CKD still depends on biopsy, which is not suitable for contraindication patients, is also traumatic, and is not sensitive to early progression. Finally, the prognosis of CKD is affected by many factors; hence, it is ineviatble to develop effective biomarkers to predict CKD prognosis and improve the prognosis through early intervention. Accurate progression monitoring and prognosis improvement of CKD are extremely significant for improving the clinical treatment and management of CKD and reducing the social burden. Therefore, biomarkers reported in recent years, which could play important roles in accurate progression monitoring and prognosis improvement of CKD, were concluded and highlighted in this review article that aims to provide a reference for both the construction of CKD precision therapy system and the pharmaceutical research and development.

Acidification of drinking water improvement tibia mass of broilers associated with the alterations in intestinal barrier and microbiota

Objective

Diet acidification supplementation is known to influence intestinal morphology, gut microbiota, and on phosphorus (P) utilization of broilers. Alterations in intestinal barrier and microbiota have been associated with systemic inflammation and thus regulating bone turnover. Hence the effect of acidifier addition to drinking water on tibia mass and the linkages between intestinal integrity and bone were studied.

Methods

One-d-old male broilers were randomly assigned to normal water (control) or continuous supply of acidified water (2% the blend of 2-hydroxy-4-methylthiobutyric acid, lactic, and phosphoric acid) group with 5 replicates of 10 chicks per replicate for 42 d.

Results

Acidification of drinking water improved the ash percentage and calcium content of tibia at 42 d. Broilers receiving acidified water had increased serum P concentration compared to control birds. The acidified group showed improved intestinal barrier, evidenced by increased wall thickness, villus height, the villus height to crypt depth ratio, and upregulated mucin-2 expression in ileum. Broilers receiving drinking water containing mixed organic acids had a higher proportion of Firmicutes and the ratio of Firmicutes and Bacteroidetes, as well as a lower population of Proteobacteria. Meanwhile, the addition of acidifier to drinking water resulted in declined ileal and serum proinflammatory factors level and increased immunoglobulin concentrations in serum. Concerning bone remodeling, acidifier addition was linked to a decrease in serum C-terminal cross-linked telopeptide of type I collagen and tartrate-resistant acid phosphatase reflecting bone resorption, whereas it did not apparently change serum alkaline phosphatase activity that is a bone formation marker.

Conclusion

Acidified drinking water increased tibia mineral deposition of broilers, which was probably linked with higher P utilization and decreased bone resorption through improved intestinal integrity and gut microbiota and through decreased systemic inflammation.

Analytical evaluation of the Nittobo Medical tartrate resistant acid phosphatase isoform 5b (TRACP-5b) EIA and comparison with IDS iSYS in different clinically defined populations

OBJECTIVES

Tartrate-resistant acid phosphatase, isoform 5b (TRACP-5b) is a bone resorption marker not influenced by renal function or food intake. TRACP-5b can be measured with Nittobo Medical enzymatic-immunoassay and IDS-iSYS automated immunoassay. We evaluated the Nittobo assay and established reference ranges for a Western-European population. We compared Nittobo and IDS results in different well-defined clinical populations.

METHODS

We established the limits of detection and quantification (LOD-LOQ), linearity, imprecision and the reference ranges in 119 males, 50 women (<45 years) and 120 women (>60 years) for TRACP-5b with the Nittobo assay. We compared both assays in 30 hemodialyzed (HD), and 40 stage 3-5 patients suffering from chronic kidney disease (CKD), 40 patients suffering from rheumatoid arthritis and osteoporosis and 80 post-menopausal women. We measured TRACP-5b, β-crosslaps (β-CTX), bone alkaline phosphatase (B-ALP) and PTH in 20 hemodialyzed (HD) and 40 CKD patients.

RESULTS

LOD and LOQ were 0.02 and 0.35 U/L. CV ranged from 8.3 to 4.3% (2/5 samples presenting CV > desirable CV). Method was linear up to of 11.3 U/L. Upper and lower limits of normality were 0.8-7.6 U/L in men, 0.9-4.7 U/L in women <45 and 0.9-7.1 U/L in women >60. The regression equation between the 2 methods was Nittobo = 1.13 (95% CI: 1.09-1.16) × iSYS - 0.4 (95% CI: -0.5; -0.3). TRACP-5b and b-ALP were in their respective reference ranges for most of CKD and HD patients. That was not the case for β-CTX, which increased with decreasing eGFR.

CONCLUSIONS

Nittobo TRACP-5b presents interesting analytical features and a good concordance with IDS iSYS. These methods could thus potentially be harmonized.

Intake of Docosahexaenoic Acid-Enriched Milk Beverage Prevents Age-Related Cognitive Decline and Decreases Serum Bone Resorption Marker Levels

The pathogenic mechanism of dementia is still unknown, and the fundamental treatment remains to be established. Thus, there is growing interest in preventing dementia through diet. One of the functional ingredients attracting attention is docosahexaenoic acid. We conducted a 12-month, randomized, double-blind, placebo-controlled clinical trial in healthy elderly Japanese individuals with a Mini-Mental State Examination score of 28 or higher at baseline using a docosahexaenoic acid-enriched milk beverage containing 297 mg docosahexaenoic acid and 137 mg eicosapentaenoic acid. Consumption of a docosahexaenoic acid-enriched milk beverage increased the fatty acid levels of docosahexaenoic acid and eicosapentaenoic acid in erythrocyte membranes, which was the primary outcome of this study. Moreover, intake of this beverage prevented age-related cognitive decline and decreased serum bone resorption marker levels. Our data demonstrate that, even at a low dose, long-term daily intake of docosahexaenoic acid prevents dementia and may show beneficial effect on bone health.

Efficacy of romosozumab in patients with osteoporosis on maintenance hemodialysis in Japan; an observational study

INTRODUCTION

Romosozumab reportedly increases bone mineral density (BMD) potently but might adversely affect cardiovascular disease (CVD). We evaluated the efficacy of romosozumab in osteoporotic HD patients with a high risk of fracture.

MATERIALS AND METHODS

This was a single-center 1-year study in Japanese HD patients. Among 96 HD romosozumab-treated HD patients with high risk of fracture, 76 HD patients completed 1 year of subcutaneous administration of romosozumab (210 mg/4 weeks) for 1 year. Romosozumab-untreated HD patients (n = 55) were also included. Changes in BMD and serum markers, together with fracture occurrence, and CVD events, were monitored.

RESULTS

During romosozumab treatment of 76 HD patients, BMD time-dependently increased significantly by 15.3% ± 12.9% at the lumbar spine (L1-4), and 7.2% ± 8.3% at the femoral neck at 1 year. Serum BAP and total P1NP increased significantly and serum TRACP-5b decreased at 4 weeks. Fragility fractures occurred in three (3.8%) patients. Hypocalcemia occurred at 4-48 weeks despite the increased dosing of active vitamin-D derivatives, but without any symptom. New CVD events occurred in 5.2% of romosozumab-treated HD patients and10.9% in romosozumab-untreated HD patients.

CONCLUSIONS

BMD was increased significantly during romosozumab treatment at the lumbar spine, and the femoral neck, respectively, at 1 year in HD patients. Hypocalcemia occurred but without any intolerable event. There was no apparent increase in CVD events during 1 year of study, suggesting romosozumab as a promising agent for HD patients with severe osteoporosis.

Diagnostic Accuracy of Noninvasive Bone Turnover Markers in Renal Osteodystrophy

RATIONALE & OBJECTIVE

Bone biopsy remains the gold standard for diagnosing renal osteodystrophy as comparable non-invasive alternatives have yet to be established. The aim of this study was to investigate the diagnostic accuracy of biochemical markers of skeletal remodeling to predict bone turnover.

STUDY DESIGN

Cross-sectional retrospective diagnostic test study.

SETTING & PARTICIPANTS

Patients with chronic kidney disease stages G4-G5D and kidney transplant recipients with successful transiliac bone biopsies.

TESTS COMPARED

Bone turnover as determined by bone histomorphometry was compared to the following biochemical markers: Full-length (1-84) parathyroid hormone (PTH), bone-specific alkaline phosphatase (BsAP), intact procollagen type I N-terminal propeptide (PINP), and tartrate-resistant acid phosphatase isoform 5b (TRAP5b).

OUTCOME

Diagnostic performance was evaluated by area under the receiver operator characteristics curve (AUC), sensitivity, specificity, and negative and positive predictive values. Optimal diagnostic cutoffs were determined in an exploration cohort (n=100) and validated in a separate cohort (n=99).

RESULTS

All biomarkers differed across categories of low 33 (17%), normal 109 (55%), and high 57 (29%) bone turnover. AUC values were in the range of 0.75 - 0.85. High negative predictive values (≥90%) were found for both high and low bone turnover, indicating the ability to rule out both conditions using the suggested biomarker cutoffs. The highest diagnostic performances were seen with combinations of biomarkers, with overall diagnostic accuracies of 90% for high turnover, and 78% for low turnover. Results were comparable for kidney transplant candidates and recipients in a sensitivity analysis.

LIMITATIONS

The single-center approach and heterogeneity of the study cohort are main limitations of this study.

CONCLUSIONS

We conclude that the diagnostic performance of biochemical markers of bone turnover is acceptable, with clinical utility in ruling out both high and low turnover bone disease.

Porous 3D Scaffolds Enhance MSC Vitality and Reduce Osteoclast Activity

In the context of an aging population, unhealthy Western lifestyle, and the lack of an optimal surgical treatment, deep osteochondral defects pose a great challenge for the public health system. Biodegradable, biomimetic scaffolds seem to be a promising solution. In this study we investigated the biocompatibility of porous poly-((D,L)-lactide-ε-caprolactone)dimethacrylate (LCM) scaffolds in contrast to compact LCM scaffolds and blank cell culture plastic. Thus, morphology, cytotoxicity and metabolic activity of human mesenchymal stromal cells (MSC) seeded directly on the materials were analyzed after three and six days of culturing. Further, osteoclastogenesis and osteoclastic activity were assessed using reverse-transcriptase real-time PCR of osteoclast-specific genes, EIA and morphologic aspects after four, eight, and twelve days. LCM scaffolds did not display cytotoxic effects on MSC. After three days, metabolic activity of MSC was enhanced on 3D porous scaffolds (PS) compared to 2D compact scaffolds (CS). Osteoclast activity seemed to be reduced at PS compared to cell culture plastic at all time points, while no differences in osteoclastogenesis were detectable between the materials. These results indicate a good cytocompatibility of LCM scaffolds. Interestingly, porous 3D structure induced higher metabolic activity of MSC as well as reduced osteoclast activity.

Bone responsiveness to parathyroid hormone is negatively associated with parathyroid hormone-lowering drug use in patients undergoing hemodialysis: a cross-sectional study

BACKGROUND

Parathyroid hormone (PTH) acts on bone to indirectly increase the number and activity of osteoclasts. Thus, PTH has a stimulatory effect on bone resorption and upregulates bone turnover. However, the responsiveness of bone to PTH varies widely among patients receiving dialysis. In fact, relative to the serum PTH level, the level of serum tartrate-resistant acid phosphatase-5b (TRACP-5b), a bone resorption marker derived from osteoclasts, varies as well. This study aimed to examine factors related to bone responsiveness to PTH in patients undergoing chronic hemodialysis (HD).

METHODS

This study included patients receiving chronic HD in Kawasaki Municipal Tama Hospital (Kanagawa, Japan) and Yonaha Medical Clinic (Okinawa, Japan) and excluded patients who received HD for less than 6 months, those who received a combination of HD and peritoneal dialysis, and those who had cancer bone metastases or myeloma. The TRACP-5b/intact PTH (iPTH) ratio was created as an index of bone responsiveness to PTH, categorized into tertiles (low, medium, and high), and a cross-sectional study was conducted. P < 0.05 indicated statistically significant differences.

RESULTS

One hundred and six patients were analyzed. Age (P = 0.010), body mass index (BMI) (P = 0.003), use of calcium-sensing receptor (CaSR) agonists (P = 0.008), use of vitamin D receptor activators (VDRAs) (P = 0.012), plasma iPTH level (P < 0.001), serum 1,25(OH)₂D level (P = 0.003), and serum TRACP-5b level (P < 0.001) were significantly different among the three categories. In the single linear regression analysis, age (P = 0.016), corrected serum calcium level (P = 0.007), and ln [1,25(OH)₂D] (P = 0.044) showed a significant positive correlation with ln [TRACP-5b/iPTH], whereas BMI (P = 0.026), use of CaSR agonists (P = 0.001), use of VDRAs (P = 0.009), and serum phosphorus level (P = 0.018) showed a significant negative correlation. Upon conducting multiple linear regression analysis incorporating significant variables in the single linear regression analysis, a significant negative correlation was observed between the TRACP-5b/iPTH ratio and intravenous administration of a CaSR agonist (etelcalcetide) and/or a VDRA (calcitriol or maxacalcitol) in all the adjusted models.

CONCLUSIONS

Bone responsiveness to PTH is negatively correlated with the intravenous administration of a CaSR agonist and/or a VDRA in patients undergoing chronic HD.

A case of hypercalcemia because of adrenal insufficiency induced by glucocorticoid withdrawal in a patient undergoing hemodialysis

Glucocorticoids are widely used for treating underlying renal diseases and following renal transplantation and are often tapered or discontinued upon reaching end-stage renal failure. Although glucocorticoid withdrawal is the predominant cause of secondary adrenal insufficiency, no consensus has been established regarding its prevalence, clinical manifestations, or therapeutic regimen, for prevention of this pathological condition. We describe a 29-year-old woman admitted to our hospital because of 1-week history of fever, diarrhea, and general fatigue. She was affected with nephrotic syndrome and diagnosed with focal segmental glomerulonephritis at 15 years old, and had since been treated with glucocorticoids. She suffered from frequent relapse of nephrotic syndrome, which became refractory to other immunosuppressants and low-density lipoprotein apheresis, making discontinuation of glucocorticoids difficult. Renal function deteriorated gradually and hemodialysis was initiated 8 months before admission. She was infected with type A influenza roughly 2 weeks prior and treated with oseltamivir. She exhibited hypercalcemia (albumin corrected, 14.4 mg/dl) and hypoglycemia (31.0 mg/dl) for the first time. She was suspected of, and diagnosed with, adrenal insufficiency, because long-term glucocorticoid use was incidentally discontinued only 2 days before she contracted influenza. Clinical symptoms and hypercalcemia improved dramatically following initiation of treatment with hydrocortisone. Adrenal insufficiency is an unusual cause of hypercalcemia. However, hemodialysis patients tend to develop more severe hypercalcemia because of lack of urinary calcium excretion, which should not be overlooked because it may result in critical situations. In conclusion, clinicians should be aware of adrenal insufficiency with glucocorticoid withdrawal and hypercalcemia in hemodialysis patients.

Biological sources of variations of tartrate-resistant acid phosphatase 5b in a healthy Japanese population

BACKGROUND

Tartrate-resistant acid phosphatase 5b (TRACP5b) is a bone resorption marker that is mainly used in clinical management of osteoporosis. For proper interpretations of test results for serum TRACP5b, we explored their biological sources of variation, esp. age-related changes, and associations with other bone-related markers in healthy Japanese adults.

METHODS

During the 2009 East-Southeast Asian multicentre study for determination of reference intervals, 72 major laboratory tests were measured by centralized assays in 3541 well-defined healthy volunteers. The current study included 1980 test results in Japanese subjects for five bone-related markers: TRACP5b, bone alkaline phosphatase, intact parathyroid hormone, calcium and inorganic phosphate. Information on sources of variation, including body mass index, smoking habits and ABO-blood group, were obtained from a health status questionnaire.

RESULTS

Gender-specific profiles of age-related changes were observed for each parameter. Increased values starting from 40 years of age in females were most prominent for TRACP5b, followed by bone alkaline phosphatase and inorganic phosphate. TRACP5b in males decreased with body mass index, bone alkaline phosphatase and TRACP5b were higher in blood type-O subjects, especially in males. TRACPT5b was closely correlated with bone alkaline phosphatase, and moderately correlated with adjusted calcium and inorganic phosphate, especially in females aged ≥45 years. Reference intervals for each analyte were determined parametrically based on gender and age.

CONCLUSIONS

This study elucidated sources of variation of TRACP5b and related bone markers in healthy Japanese subjects and demonstrated a specific age profile for each marker. These results are of relevance for better clinical usage and interpretations of serum levels of bone markers.

Gamabufotalin Inhibits Osteoclastgenesis and Counteracts Estrogen-Deficient Bone Loss in Mice by Suppressing RANKL-Induced NF-κB and ERK/MAPK Pathways

Osteolytic bone disease is a condition of imbalanced bone homeostasis, characterized mainly by excessive bone-resorptive activity, which could predispose these populations, such as the old and postmenopausal women, to developing high risk of skeletal fragility and fracture. The nature of bone homeostasis is the coordination between the osteoblasts (OBs) and osteoclasts (OCs). Abnormal activation of osteoclasts (OCs) could compromise the bone homeostasis, constantly followed by a clutch of osteolytic diseases, including postmenopausal osteoporosis, osteoarthritis, and rheumatoid arthritis. Thus, it is imperatively urgent to explore effective medical interventions for patients. The traditional Chinese medicine (TCM) gamabufotalin (CS-6) is a newly identified natural product from Chansu and has been utilized for oncologic therapies owing to its good clinical efficacy with less adverse events. Previous study suggested that CS-6 could be a novel anti-osteoporotic agent. Nevertheless, whether CS-6 suppresses RANK-(receptor activator of nuclear factor-κ B ligand)/TRAF6 (TNF receptor-associated factor 6)-mediated downstream signaling activation in OCs, as well as the effects of CS-6 on OC differentiation in vivo, remains elusive. Therefore, in this present study, we aimed to explore the biological effects of CS-6 on osteoclastogenesis and RANKL-induced activation of related signaling pathways, and further to examine the potential therapeutic application in estrogen-deficient bone loss in the mice model. The results of in vitro experiment showed that CS-6 can inhibit RANKL-induced OC formation and the ability of bone resorption in a dose-dependent manner at both the early and late stages of osteoclastogenesis. The gene expression of OC-related key genes such as tartrate-resistant acid phosphatase (TRAP), CTSK, DC-STAMP, MMP9, and β3 integrin was evidently reduced. In addition, CS-6 could mitigate the systemic estrogen-dependent bone loss and pro-inframammary cytokines in mice in vivo. The molecular mechanism analysis suggested that CS-6 can suppress RANKL/TRAF6-induced early activation of NF-κB and ERK/MAPK signaling pathways, which consequently suppressed the transcription activity of c-Fos and NFATc1. Taken together, this present study provided ample evidence that CS-6 has the promise to become a therapeutic candidate in treating osteolytic conditions mediated by elevated OC formation and bone resorption.

The Non-invasive Diagnosis of Bone Disorders in CKD

Abnormal bone metabolism is an integral part of the chronic kidney disease-mineral bone disorder (CKD-MBD). For several reasons, the difficult bone compartment was neglected for some time, but there has been renewed interest as a result of the conception of bone as a new endocrine organ, the increasing recognition of the cross-talk between bone and vessels, and, especially, the very high risk of osteoporotic fractures (and associated mortality) demonstrated in patients with CKD. Therefore, it has been acknowledged in different guidelines that action is needed in respect of fracture risk assessment and the diagnosis and treatment of osteoporosis in the context of CKD and CKD-MBD, even beyond renal osteodystrophy. These updated guidelines clearly underline the need to improve a non-invasive approach to these bone disorders in order to guide treatment decisions aimed at not only controlling CKD-MBD but also decreasing the risk of fracture. In this report, we review the current role of the most often clinically used or promising biochemical circulating biomarkers such as parathyroid hormone, alkaline phosphatases, and other biochemical markers of bone activity as alternatives to some aspects of bone histomorphometry. We also mention the potential role of classic and new imaging techniques for CKD patients. Information on many aspects is still scarce and heterogeneous, but many of us consider that it is indeed time for action, recognizing our definitely limited ability to base certain treatment decisions only on our current non-comprehensive knowledge.

Bone and Mineral Metabolism in Children with Nephropathic Cystinosis Compared with other CKD Entities

CONTEXT

Children with nephropathic cystinosis (NC) show persistent hypophosphatemia, due to Fanconi syndrome, as well as mineral and bone disorders related to chronic kidney disease (CKD); however, systematic analyses are lacking.

OBJECTIVE

To compare biochemical parameters of bone and mineral metabolism between children with NC and controls across all stages of CKD.

DESIGN

Cross-sectional multicenter study.

SETTING

Hospital clinics.

PATIENTS

Forty-nine children with NC, 80 CKD controls of the same age and CKD stage.

MAIN OUTCOME MEASURES

Fibroblast growth factor 23 (FGF23), soluble Klotho, bone alkaline phosphatase (BAP), tartrate-resistant acid phosphatase 5b (TRAP5b), sclerostin, osteoprotegerin (OPG), biochemical parameters related to mineral metabolism, and skeletal comorbidity.

RESULTS

Despite Fanconi syndrome medication, NC patients showed an 11-fold increased risk of short stature, bone deformities, and/or requirement for skeletal surgery compared with CKD controls. This was associated with a higher frequency of risk factors such as hypophosphatemia, hypocalcemia, low parathyroid hormone (PTH), metabolic acidosis, and a specific CKD stage-dependent pattern of bone marker alterations. Pretransplant NC patients in mild to moderate CKD showed a delayed increase or lacked an increase in FGF23 and sclerostin, and increased BAP, TRAP5b, and OPG concentrations compared with CKD controls. Post-transplant, BAP and OPG returned to normal, TRAP5b further increased, whereas FGF23 and PTH were less elevated compared with CKD controls and associated with higher serum phosphate.

CONCLUSIONS

Patients with NC show more severe skeletal comorbidity associated with distinct CKD stage-dependent alterations of bone metabolism than CKD controls, suggesting impaired mineralization and increased bone resorption, which is only partially normalized after renal transplantation.

Diaphyseal femoral fracture due to severe vitamin D3 deficiency and low parathyroid hormone levels on long-term hemodialysis: a case report

INTRODUCTION

Currently, there are no reports of diaphyseal femoral fracture equivalent to atypical femoral fractures (AFFs) in patients receiving long-term hemodialysis (HD).

CASE REPORT

A 56-year-old Japanese man receiving long-term HD for 34 years was admitted to our hospital due to a delay in postoperative healing. The patient began maintenance hemodialysis at 22 years of age. The patient then underwent surgical parathyroidectomy (PTX) for secondary hyperparathyroidism at 43 years of age, which resulted in decreased levels of parathyroid hormone (PTH). Thereafter, this patient's serum 1,25(OH)₂ D₃ level was very low because active vitamin D₃ derivative was not administered. At 54 years of age, a transverse fracture of the femoral shaft equivalent to AFF occurred. Surgery with open reduction and internal fixation using intramedullary nailing was performed; however, the delay of postoperative healing continued for 16 months. A left iliac crest bone biopsy was performed and showed osteoid-like lesion and an increase of woven bone. The patient received active vitamin D₃ derivative and recombinant human PTH (1-34) derivative. Twenty-nine months after the first surgery, a reoperation was performed. Simultaneously, a right iliac crest bone biopsy was performed. Bone morphometrical improvement was confirmed. Six months after resurgery, the bone union was achieved. Severe vitamin D₃ deficiency and decreased levels of PTH may induce a higher osteoid state and an increase of woven bone, which may then attribute to the development of diaphyseal femoral fracture and impairment of postoperative bone healing. It is hypothesized that treatment with active vitamin D₃ and teriparatide acetate may be a therapeutic option via the accelerated formation of lamellar bone for refractory diaphyseal femoral fracture of long-term dialysis.

Calcium affects sternal mass by effects on osteoclast differentiation and function in meat ducks fed low nutrient density diets

Genetic progress and increasing nutrient density for greater body mass and meat yield in poultry has inadvertently led to an imbalance between pectorales mass and sternal development which may or may not be detrimental to productivity and welfare. Slowing weight gain while promoting bone mineralization could positively influence sternal health. Thus, the present study aimed to evaluate the effect of graded calcium (Ca) supplementation in low nutrient density (LND) diets on sternal mass and bone turnover in meat ducks. Male meat ducks (720, 15-day-old) were randomly assigned and fed a standard nutrient density positive control (PC) diet, and 4 LND diets with 0.5, 0.7, 0.9, and 1.1% Ca, respectively. Metabolic energy (ME) was reduced in the LND by 9.5 and 16.3% at 15-35 D and 36-56 D compared to PC diet, respectively, while maintaining proportionate essential nutrient proportions to energy similar as in the PC diet. Although the 0.9% Ca LND diet decreased body weight and sternal dimension, it increased the relative sternum weight, the trabecular bone volume/tissue volume (BV/TV) and Ca content of the sternum compared with PC diet. Feeding 0.7% or more Ca with the LND diet significantly increased the mineral content, bone density, BV/TV, and trabecular number of the sternum for 49-days-old ducks. Furthermore, the LND diet with 0.7% or more Ca-increased osteocyte-specific gene mRNA and osteoprotegerin (OPG) expression, and it blocked the expression of cathepsin K and decreased osteoclasts number per bone surface. Tartrate-resistant acid phosphatase (TRAP) staining also revealed that the addition 0.7% or more Ca to the LND diet significantly decreased the number of osteoclasts compared with the 0.5% Ca LND diet. Meanwhile TRAP activity in serum was significantly decreased in 0.7% or more Ca-treated groups. We concluded that LND diet with 0.7% or more Ca may maintain optimal sternal mass through suppressing bone resorption for meat duck.

Study on the morphology and mineralization of the tibia in meat ducks from 1 to 56 d

The objective of this current study was to characterize the basic physiological data on morphological and mineralized properties of the tibia from 1 to 56 days, as well as the interrelationships of body weight (BW) and bone traits for meat ducks. A total of 176 1-d-old ducks was allocated into eight pens and fed with the same diet until the age of 56 d. Eight birds (1 ducks/pen) were randomly selected weekly for measuring BW and tibia characteristics. The BW of duck was increased with age throughout the whole study. Tibial length and width rapidly grew from 1 to 35 d, when it leveled off. The fat-free weight, ash, calcium (Ca) and phosphorus (P) content of tibia increased rapidly from 1 to 42 d and reached its plateau from 42 d onward. Tibial density and tibia-breaking strength increased in a regular manner with age until 42 d. Serum alkaline phosphatase activity was higher between 1 to 7 d in the duck. Regression and ontogenetic scaling analysis showed the age of maximal growth rate in tibia dimension and mineralization was earlier than that in BW; when compared with BW, tibial fat-free weight and tibia-breaking strength increased isometrically, tibia length displayed a negative allometry, and tibial width showed a positive allometric growth. Results indicate that the tibia displayed rapid bone growth (1 to 35 d) and mineralization (1 to 42 d), and alkaline phosphatase (ALP) plays a critical role in the early stage of tibia mineralization of meat duck. Intensive selection for growth rate in ducks has resulted in tibial morphology changes, which represents an interesting compromise of adaptation for increasing BW.

Bone biomarkers in de novo renal transplant recipients

Successful kidney transplantation (partly) corrects the physiologic and metabolic abnormalities driving chronic kidney disease - mineral and bone disorders. At the same time, renal transplant recipients are exposed to immunosuppressive agents that may affect bone metabolism. Bone biomarkers have been suggested as surrogates of or adjuncts to bone biopsy and imaging techniques to assess bone health and to classify risk of bone loss and fractures. Bone biomarkers may be classified as circulating factors that affect bone metabolism (commonly referred to as bone metabolism markers) or that reflect bone cell number and/or activity (commonly referred to as bone turnover markers). A growing body of evidence shows that successful renal transplantation has a major impact on both bone metabolism and bone turnover. Analytical issues, including the cross-reactivity with fragments, complicate the interpretation of bone biomarkers, especially in the setting of a rapid changing kidney function, as is the case after successful renal transplantation. Overall, bone turnover seems to decline following renal transplantation, but inter-individual variability is substantial. Preliminary evidence indicates that bone biomarkers may be useful in guiding mineral and bone therapy in renal transplant recipients.

Denosumab Improves Glomerular Filtration Rate in Osteoporotic Patients With Normal Kidney Function by Lowering Serum Phosphorus

Higher serum phosphorus (Pi) increases the risk for chronic kidney disease (CKD). It was reported that a single administration of denosumab or zoledronate significantly suppressed serum Pi levels as well as those of bone resorption markers in serum. Also, previous evidences suggest a link between bone anti-resorptive therapy and vasoprotective/renoprotective effects through mechanisms that remain unexplored. The aim of this study is to assess the renoprotective effect of denosumab and involvement of denosumab-induced reduction in serum Pi in osteoporotic patients. Osteoporotic patients (n = 73) without overt proteinuria in dipstick test results were treated with denosumab (60 mg) every 6 months during the study period (24 months). Estimated glomerular filtration rate based on serum cystatin C (eGFRcys) was used as a filtration marker and tartrate-resistant acid phosphatase-5b (TRACP-5b) as a bone resorption marker. For analysis of non-CKD patients (n = 56), those with eGFRcys <60 mL/min/1.73 m² were excluded. A single injection of denosumab suppressed serum Pi as well as TRACP-5b during the first 6 months, whereas age-related decline in eGFRcys was significantly reversed, with an increase of 2.75 ± 1.2 mL/min/1.73 m² after 24 months noted. Multivariate analysis showed that serum Pi reduction following the initial denosumab injection was positively associated with serum TRACP-5b suppression during that same period (β = 0.241, p = 0.049). In addition, a positive association of serum Pi suppression, but not of corrected calcium or TRACP-5b, with eGFRcys increase after 24 months (β = 0.321, p = 0.014) was found after adjustments for gender, age, BMI, antihypertensive drug use, albumin, and eGFRcys. The same was observed in osteoporotic cases restricted to non-CKD patients. In conclusion, serum Pi reduction resulting from phosphorus load decrement from bone induced by denosumab is a determinant for eGFRcys increase. Early introduction of bone antiresorptive therapy can retain glomerular filtration in osteoporosis cases, including non-CKD patients. © 2019 American Society for Bone and Mineral Research.

HIF1α inhibition facilitates Leflunomide-AHR-CRP signaling to attenuate bone erosion in CRP-aberrant rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by progressive bone erosion. Leflunomide is originally developed to suppress inflammation via its metabolite A77 1726 to attenuate bone erosion. However, distinctive responsiveness to Leflunomide is observed among RA individuals. Here we show that Leflunomide exerts immunosuppression but limited efficacy in RA individuals distinguished by higher serum C-reactive protein (CRP^Higher, CRP^H), whereas the others with satisfactory responsiveness to Leflunomide show lower CRP (CRP^Lower, CRP^L). CRP inhibition decreases bone erosion in arthritic rats. Besides the immunomodulation via A77 1726, Leflunomide itself induces AHR-ARNT interaction to inhibit hepatic CRP production and attenuate bone erosion in CRP^L arthritic rats. Nevertheless, high CRP in CRP^H rats upregulates HIF1α, which competes with AHR for ARNT association and interferes Leflunomide-AHR-CRP signaling. Hepatocyte-specific HIF1α deletion or a HIF1α inhibitor Acriflavine re-activates Leflunomide-AHR-CRP signaling to inhibit bone erosion. This study presents a precision medicine-based therapeutic strategy for RA.

Leflunomide is used for the treatment of rheumatoid arthritis. Here, the authors show that effectiveness is limited in patients with higher levels of serum c-reactive protein (CRP). Using animal models, they show that higher CRP induces HIF1a expression, which in turn interferes with Leflunomide signalling, and that effectiveness of the drug is restored when HIF1a is pharmacologically inhibited.

Low Bone Mineral Density and High Bone Turnover in Patients With Non-Hodgkin's Lymphoma (NHL) Who Receive Frontline Therapy: Results of a Multicenter Prospective Study

Chemotherapy associated osteoporosis is a severe problem in patients with malignant diseases as it increases the risk for fractures and deteriorates quality of life. There are very limited data in the literature for the effect of chemotherapy on bone metabolism of adult patients with Non-Hodgkin Lymphoma (NHL). We prospectively evaluated bone remodeling pre- and post-chemotherapy in 61 patients with newly diagnosed NHL. First-line chemotherapy resulted in high bone turnover, which led to increased bone loss and reduced bone mineral density (BMD) of lumbar spine (L1-L4) and femur neck (FN). The reduction of L1-L4 and FN BMD post-chemo was more profound in males and in older patients (>55 years). Patients who received 8 cycles of chemotherapy had a greater reduction of L1-L4 and FN BMD as compared to 6 cycles. The administration of chemotherapy also resulted in a dramatic increase of bone resorption markers (CTX and TRACP-5b), bone formation markers, (bALP and Osteocalcin) and of osteoblast regulator Dickkopf-1. During study period, one patient had a pathological fracture in his right FN.

Daily oligofructose-enriched inulin intake impacts bone turnover markers but not the cytokine profile in pediatric patients with celiac disease on a gluten-free diet: Results of a randomised, placebo-controlled pilot study

BACKGROUND

Bone metabolism disturbances are commonly observed in patients with newly diagnosed celiac disease (CD). The only available treatment for CD-the intake of a gluten-free diet (GFD)-has been found to be insufficient in effectively improving bone health in some patients. Therefore, there is an urgent need to modify the GFD so as to allow for the provision of all the necessary nutrients and improved absorption. Prebiotics intake reportedly improves the absorption of bone-related vitamin D and calcium as well as bone metabolism. The effect of prebiotic intake on bone health in CD patients has not been studied yet. This study aimed to evaluate the effect of oligofructose-enriched inulin intake on bone metabolism and immune response in children with CD on a GFD.

METHODS

A total of 34 children with CD were randomised into two groups receiving 10 g of oligofructose-enriched inulin (Synergy 1) or a placebo (maltodextrin) for three months, together with a strict GFD. The children's bone metabolism marker levels and cytokine profiles were analysed before and after the intervention.

RESULTS

After supplementation, the concentration of osteocalcin increased significantly in children receiving Synergy 1, while the concentration of bone alkaline phosphatase increased in both groups, independent of supplementation. After the intervention, the level of pyridinoline increased significantly in the placebo group, resulting in a concentration that was two times higher than that in the Synergy 1 group, in which it remained stable. Moreover, the plasma concentrations of N-terminal telopeptides of type I collagen decreased in both the groups, whereas the tartrate-resistant acid phosphatase 5b level increased particularly in the Synergy 1 group. The intervention did not lead to immunological response changes.

CONCLUSIONS

The proposed supplementation beneficially altered bone metabolism, through increased bone formation rates and decreased bone resorption process rates. Supplementation of GFD with prebiotic oligofructose-enriched inulin may be a promising auxiliary therapy for bone metabolism improvements in children with CD.

Impaired residual renal function predicts denosumab-induced serum calcium decrement as well as increment of bone mineral density in non-severe renal insufficiency

Denosumab treatment of osteoporotic patients, except those with severe renal insufficiency, reduced cCa levels. Low baseline cCa, low estimated glomerular filtration rate, and high bone turnover increased the risk of lower cCa, while increasing bone mineral density. Pretreatment with antiresorptive agents was beneficial in reducing the risk of hypocalcemia.

INTRODUCTION

Although denosumab-induced hypocalcemia has been frequently observed in patients with chronic kidney disease (CKD) stages 4-5D being treated with denosumab for osteoporosis, few studies have assessed the risk factors for serum-corrected calcium (cCa) reductions in patients with non-severe renal insufficiency. This study assessed the risk factors for reduced cCa concentration following denosumab administration and analyzed factors predictive of changes in bone mineral density (BMD).

METHODS

Seventy-seven osteoporotic patients, not including those with CKD stages 4-5D, were treated with 60 mg denosumab once every 6 months. Biochemical parameters and BMD were analyzed from prior to the initial dose until 1 month after the second dose.

RESULTS

Following the first administration of denosumab, cCa levels decreased, reaching a minimum on day 7. Multiple linear regression analyses showed that baseline cCa, estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m², tartrate-resistant acid phosphatase-5b (TRACP-5b), and bone alkaline phosphatase (BAP) or pretreatment with antiresorptive agents were significant factors independently associated with the absolute reduction in cCa from baseline to day 7 (ΔcCa_0-7 days). ΔcCa_0-7 days after the second dose of denosumab was significantly lower than that after the first dose. After 6 months of denosumab treatment, both LS-BMD and FN-BMD significantly increased from baseline. LS-BMD and FN-BMD correlated significantly with baseline TRACP-5b or BAP and eGFR, respectively.

CONCLUSIONS

Both low eGFR and high bone turnover were independent risk factors for denosumab-induced cCa decrement, and for increases in BMD. Pretreatment with antiresorptive agents may reduce the risk of hypocalcemia.

Effect of Usnic Acid on Osteoclastogenic Activity

Osteoclasts are the only cells that can resorb bone and they are produced from monocytes/macrophages in the presence of M-CSF and RANKL and are activated in vivo by an immune response. Usnic acid is a secondary metabolite of lichen and has a unique dibenzofuran skeleton. It has been used for years in cosmetics, fragrances, and traditional medicines. It has a wide range of bioactivities, including anti-inflammatory, anti-bacterial, anti-cancer, anti-viral, and so on. However, the anti-osteoclastogenic activity of usnic acid has not been reported yet. In this study, we investigated whether usnic acid could affect RANKL-mediated osteoclastogenesis. Usnic acid significantly inhibited RANKL-mediated osteoclast formation and function by reducing the transcriptional and translational expression of NFATc1, a master regulator of osteoclastogenesis. In addition, it prevented lipopolysaccharides (LPS)-induced bone erosion in mice. Taken together, our results suggest that usnic acid might be a potential candidate for the treatment of osteoporosis.

A study on the sternum growth and mineralization kinetic of meat duck from 35 to 63 days of age

The sternum as an important part of the skeleton and not only provides a crucial attachment site for the pectoral muscles and protects internal organs such as the heart and lungs for meat duck, but may also be considered as the primary ventilator in the avian respiratory system. Therefore, this study focuses on the sternum growth and mineralization kinetics of ducks from 35 d to 63 d of age. A total of 72 one-d-old males and 72 females were chosen and fed with the same diet until the age of 9 weeks. The sternum and serum were harvested at 35 d, 42 d, 49 d, 56d, and 63 d of feeding. Results showed that the sternum width rapidly grew from 35 d to 42 d and the value changed little after 42 d, while the keel length and the sternum depth did not significantly change until 49 d age. The sternum defatted weight and density increased assumed to "S" with ducks' age and their plateau in the 56 d. The sternum ash content, calcium (Ca), and phosphate (P) levels increased with duck age, then all three reached a plateau in 49 days. Similarly, serum alkaline phosphatase (ALP) activity was higher in the ducks at both 35 and 42 days, followed by 49 days, and the value was lowered to a minimum on both days 56 and 63. Conversely, serum tartrate resistant acid phosphatase (TRAP) activity substantially increased until 49 days irrespective of duck gender. Results indicate that the dimensions of the sternum were already at the maximum in 49-day-old ducks and the sternum of the ducks rapidly mineralized from 42 d to 49 d of age and achieved a plateau phase after 49-days resulting from the high activity of ALP at the sternum early mineralization.

Multiscale investigation on the effects of additional weight bearing in combination with low-magnitude high-frequency vibration on bone quality of growing female rats

This study aimed to explore the effects of additional weight bearing in combination with low-magnitude high-frequency vibration (LMHFV; 45 Hz, 0.3 g) on bone quality. One hundred twenty rats were randomly divided into ten groups; namely, sedentary (SED), additional weight bearing in which the rat wears a backpack whose weight is x% of the body weight (WBx; x = 5, 12, 19, 26), basic vibration (V), and additional weight bearing in combination with LMHFV in which the rat wears a backpack whose weight is x% of the body weight (Vx; x = 5, 12, 19, 26). The experiment was conducted for 12 weeks, 7 days per week, and 15 min per day. A three-point bending mechanical test, micro computed tomography, and a nanoindentation test were used. Serum samples were analyzed chemically. Failure load in V19 rats was significantly lower than that in SED rats (P < 0.05). Vx (x = 5, 12, 19, 26) rats showed poor microarchitectures. The content of tartrate-resistant acid phosphatase 5b was significantly higher in Vx (x = 5, 12, 19, 26) rats than that in SED rats (P < 0.05). V26 rats demonstrated comparatively better nanomechanical properties of materials than the other vibrational groups. Additional weight bearing in combination with LMHFV negatively affected the macromechanical properties and microarchitecture of bone. Heavy additional weight bearing, such as 26% of body weight, in combination with LMHFV was able to improve the nanomechanical properties of growing bone material compared with LMHFV. A combined mechanical stimulation was used, which may provide useful information to understand the mechanism of this mechanical stimulation on bone.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Inhibition of GSK-3β increases trabecular bone volume but not cortical bone volume in adenine-induced uremic mice with severe hyperparathyroidism

Patients with chronic kidney disease (CKD) are at increased risk for bone fractures compared with the general population. Repression of the Wnt/β‐catenin signaling pathway is associated with bone abnormalities. Inhibition of glycogen synthase kinase (GSK)‐3β, a critical component of the Wnt/β‐catenin signaling pathway, increases bone volume through accumulation of β‐catenin. It remains unknown whether inhibition of GSK‐3β increases bone volume in CKD. The present in vivo study examined the effects of GSK‐3β inhibition on bone volume in CKD mice. Wild‐type mice were divided into three groups. One group was fed a control diet (CNT) and the other two groups were fed a diet containing 0.2% adenine and given water with or without lithium chloride (LiCl), a GSK‐3 inhibitor (CKD, CKD+LiCl, respectively). GSK‐3β heterozygous knockout mice were fed a diet containing 0.2% adenine (CKD‐GSK‐3β^+/−). After 6 weeks, trabecular and cortical bone volumes of the femur were analyzed using microcomputed tomography. CKD mice developed azotemia, hyperphosphatemia, and hyperparathyroidism, followed by a decrease in cortical bone volume without any change in trabecular bone volume. Serum levels of urea nitrogen, phosphate, and parathyroid hormone were comparable among the three groups of CKD mice. Trabecular bone volume increased in CKD‐GSK‐3β^+/− and CKD+LiCl mice compared with CNT and CKD mice. However, there were no significant differences in cortical bone volume among the three groups of CKD mice. The results suggest that inhibition of GSK‐3β increases trabecular bone volume but not cortical bone volume in adenine‐induced uremic mice with uncontrolled hyperparathyroidism.

Variations of parathyroid hormone and bone biomarkers are concordant only after a long term follow-up in hemodialyzed patients

End-stage renal disease is associated with mineral and bone disorders. Guidelines recommending therapies should be based on serial assessments of biomarkers, and thus on variations (Δ), rather than scattered values. We analyzed the correlations between ΔPTH and Δbone biomarkers such as bone-specific alkaline phosphatase (b-ALP), Beta-CrossLaps (CTX), osteocalcin, intact serum procollagen type-1 N-propeptide (P1NP), and tartrate-resistant acid phosphatase 5B (TRAP-5B) at different time-points. In this prospective observational analysis, variations of biomarkers were followed after 6-week (n = 129), 6-month (n = 108) and one-year (n = 93) period. Associations between variations were studied by univariate linear regression. Patients followed for one-year period were classified (increaser or decliner) according to variations reaching the critical difference. Over the 6-week period, only ΔCTX was correlated with ΔPTH (r = 0.38, p < 0.0001). Over the one-year period, correlations between ΔPTH and Δbone biomarkers became significant (r from 0.23 to 0.47, p < 0.01), except with ΔTRAP-5b. Correlations between Δbone biomarkers were all significant after one-year period (r from 0.31 to 0.68, p < 0.01), except between Δb-ALP and ΔTRAP-5b. In the head-to-head classifications (decliners/increasers), the percentage of concordant patients was significantly higher over the one-year than the 6-week period. A concordance between ΔPTH and Δbone biomarkers is observed in dialysis patients, but only after a long follow-up.

Bufalin attenuates cancer-induced pain and bone destruction in a model of bone cancer

Bufalin is a natural anti-inflammatory small molecule. Given the close relationship between inflammation and cancer, many scholars have studied the effect of bufalin on cancer in vitro, but in vivo research is still lacking. A murine bone cancer model was used in this study. We conducted pain sensitive test on mice with bone cancer, by nocifensive behavior, mechanical allodynia, and thermal hyperalgesia. Serum levels of bone loss markers with bufalin treatment were measured by ELISA. Expressions of osteoprotegerin (OPG) and receptor activator of NF-κB ligand (RANKL) were analyzed in bufalin-treated mice by real-time PCR and Western blot. Cannabinoid 2 receptor (CB2) inverse agonist AM630 was administrated to mice with bone cancer together with bufalin. Bufalin relieved cancer-induced pain and bone destruction in the murine bone cancer model. Serum levels of bone loss markers after bufalin treatment were reduced. Bufalin upregulated OPG and downregulated RANKL. The CB2 receptor inverse agonist, AM630, reduced the pain relief of bufalin treatment in the mouse bone cancer model. This study demonstrates that bufalin relieves cancer-induced pain and bone destruction, which is mediated through the CB2 receptor.

Biomarkers Predicting Bone Turnover in the Setting of CKD

PURPOSE OF THE REVIEW

Impaired bone quality contributes to the increased fracture risk in chronic kidney disease patients. Both low and high turnover bone disease may compromise bone quality. The question arises whether bone biomarkers may be additive or replace bone histormorphometry for diagnosing the extremes of bone turnover.

RECENT FINDINGS

Studies exploring the performance of established and emerging bone biomarkers against histomorphometric assessment of bone turnover are limited and overall yield inconclusive results as to their diagnostic utility. Bone biomarkers, although promising, currently fail to meet the needed diagnostic accuracy to replace bone histomorphometry and thus are not yet ready for clinical use. Bone biomarkers have not only several advantages, but also important limitations such as high biological variability, retention with kidney disease, preanalytical issues, and interassay variability. These important issues must be considered when developing and evaluating bone biomarkers. There is an urgent need for harmonization and standardization of available assays and additional bone biopsy studies.

Circulating markers of bone turnover

Renal osteodystrophy is a feature of chronic kidney disease (CKD), with increasing prevalence as CKD progresses. This bone disease is responsible for major morbidity, including fractures, and a deterioration in the quality of life and its sequelae. Circulating biomarkers of renal osteodystrophy typically indicate bone turnover, but not other features of bone, like bone volume, mineralization, quality or strength. Bone turnover can be considered to be primarily a reflection of bone cell activity, in particular that of osteoblasts and osteoclasts. Since current treatments for bone disease usually target cellular activity, biomarkers are considered to be able to contribute to the decision-making for treatment and its follow-up. In CKD, one has to consider the impact of a diminished clearance of biomarkers or their altered metabolism, both potentially limiting its clinical use. Here, several aspects of the most frequently used biomarkers of bone turnover are reviewed, with an emphasis on the specific situation represented by CKD. This review is based on the overview lecture at the symposium held in Amsterdam, September 23, 2016: “The Bone In CKD”, organized by the CKD-MBD working group of ERA-EDTA.

The effect of nephrectomy on Klotho, FGF-23 and bone metabolism

Background

Increased concentration of fibroblast growth factor 23 (FGF-23) and decreased levels of soluble Klotho (sKL) are linked to negative clinical outcomes among patients with chronic kidney disease and acute kidney injury. Therefore, it is reasonable to hypothesize that GFR reduction caused by nephrectomy might alter mineral metabolism and induces adverse consequences. Whether nephrectomy due to urological indications causes derangements in FGF-23 and sKL has not been studied. The aim of the study was to evaluate the effect of acute GFR decline due to unilateral nephrectomy on bone metabolism, FGF-23 and sKL levels.

Methods

This is a prospective, single-centre observational study of patients undergoing nephrectomy due to urological indications. Levels of C-terminal FGF-23 (c-FGF-23), sKL and bone turnover markers [β-crosslaps (CTX), bone-specific alkaline phosphatase (bALP) and tartrate-resistant acid phosphatase 5b (TRAP 5b)] were measured before and after surgery (5 ± 2 days).

Results

Twenty-nine patients were studied (14 females, age 63.0 ± 11.6, eGFR 87.3 ± 19.2 ml/min/1.73 m²). After surgery, eGFR significantly declined (p < 0.0001). Nephrectomy significantly decreased sKL level [709.8 (599.9–831.2) vs. 583.0 (411.7–752.6) pg/ml, p < 0.001] and did not change c-FGF-23 concentration [70.5 (49.8–103.3) vs. 77.1 (60.5–109.1) RU/ml, p = 0.9]. Simultaneously, alterations in bone turnover markers were observed. Serum concentration of CTX increased [0.49 (0.4–0.64) vs. 0.59 (0.46–0.85) ng/ml, p = 0.001], while bALP and TRAP 5b decreased [23.6 (18.8–31.4) vs. 17.9 (15.0–22.0) U/l, p < 0.0001 and 3.3 (3.0–3.7) vs. 2.8 (2.3–3.2) U/l, p < 0.001, respectively].

Conclusions

Nephrectomy among patients with preserved renal function before surgery does not increase c-FGF-23 but reduces sKL. Moreover, nephrectomy results in derangements in bone turnover markers in short-term follow-up. These changes may participate in pathogenesis of bone disease after nephrectomy.

Bone turnover rate and bone formation/resorption balance during the early stage after switching from a bone resorption inhibitor to denosumab are predictive factors of bone mineral density change

Objectives

This study aimed to investigate the correlation between bone mineral density (BMD) and the turnover rate [√(MoMf² + MoMr²), multiple of median formation (MoMf) was calculated as bone-specific alkaline phosphatase (BAP) value/18.6 and multiple of median resorption (MoMr) as tartrate-resistant acid phosphatase 5b (TRACP-5b) value/463] and the balance (MoMf/MoMr) and to compare differences in therapeutic effects evoked by differences in previous treatments.

Methods

In 51 osteoporotic women treated with bisphosphonates (BPs) or selective estrogen receptor modulators (SERMs), BMD was measured at 0, 24, and 48 weeks after denosumab administration. The values of BAP and TRACP-5b were measured at 0, 4, 12, 24, 36, and 48 weeks.

Results

The turnover rate decreased at week 4 and decreased further at week 12. The balance indicated a relative predominantly formative state at week 4. This balance became higher in the SERM group than in the BP group at week 4. A correlation was observed between the rate of BMD change and turnover rate at weeks 0 and 4.

Conclusions

It is necessary to evaluate the turnover rate and balance to determine the therapeutic effect of denosumab, which induces dissociation between the trends in the bone turnover markers. Turnover rate and balance during the early stages of denosumab treatment may be predictive factors of BMD. When switching from bone resorption inhibitors to denosumab, it was necessary to consider the beginning values that were affected by the previous treatment. The state of relative anabolism is greater at 4 weeks when the previous treatment involved SERMs rather than BPs.

Fetal Bone Formation Is Decreased from Middle Pregnancy to Birth

Fetal bone development is a complex process that is regulated and maintained by minerals, hormones, and growth factors delivered from the mother via the placenta. Various biochemical markers of fetal bone development have been identified. However, many aspects of this process remain unclear. The aim of the study was to measure the activities of serum tartrate-resistant acid phosphatase type 5b (TRACP 5b) as a bone resorption marker and bone alkaline phosphatase (BAP) as a bone formation marker in preterm and term neonates, and to investigate fetal bone development in middle and late pregnancy. The study included 111 neonates (87 preterm and 24 term) born at Dokkyo Medical University Hospital. Neonates with illnesses and maternal diseases were excluded. Serum samples were collected within 3 hours after birth and stored at -80°C. Univariate and multivariate linear regression analyses were performed. The 111 neonates (median birth weight, 1,510 g) were born at a median of 31.3 weeks of gestation, and had TRACP 5b and BAP activities of 10.9 ± 4.0 U/L and 127.5 ± 49.2 U/L, respectively. TRACP 5b activity showed a tendency to be higher in term neonates, while BAP activity tended to be lower in term neonates. Importantly, TRACP 5b activity was positively correlated with gestational age and birth weight, and BAP activity was negatively correlated with gestational age, rate of born small-for-gestational-age neonates, and birth weight. These results suggest that bone formation during fetal growth is gradually decreased from middle pregnancy to birth, whereas bone resorption is gradually increased.