Use of Bone Turnover Markers in Clinical Osteoporosis Assessment in Women: Current Issues and Future Options

Pathological tissue formation and degradation biomarkers correlate with patient reported pain outcomes: an explorative study

Background

The lack of disease modifying drugs in Osteoarthritis (OA) may be attributed to the difficulty in robust response based on patient-reported outcomes (PROs) linked to drug mechanism of action. Joint tissue turnover biomarkers are associated with disease progression. A subset of patients has elevated serum levels of CRP metabolite (CRPM). This explorative study investigates the associations between PROs and joint tissue turnover markers in patients with high or low CRPM.

Methods

Serum of 146 knee OA patients of the New York Inflammation cohort and 21 healthy donors were assessed for biomarkers of collagen degradation (C1M, C2M, C3M, C4M), formation (PRO-C1, PRO-C2, PRO-C3, PRO-C4), and CRPM. Mean (SD) age was 62.5 (10.1); BMI, 26.6 (3.6); 62% women; and, 67.6% had symptomatic OA. WOMAC pain, stiffness, function, and total were recorded at baseline and at two-year follow-up. Associations were adjusted for race, sex, age, BMI, and NSAID.

Results

There was no difference in markers between donors and patients. C2M correlated with the WOMAC scores in all CRPM groups. Significant correlations were observed between PROs and PRO-C4, C1M, and C3M in the CRPMhigh group. The best predictive models for improvement were found for function and total with AUCs of 0.74 (p ​< ​0.01) and 0.78 (p ​< ​0.01). The best predictive models for worsening were found for function and total with AUCs of 0.84 (p ​< ​0.01) and 0.80 (p ​< ​0.05).

Conclusion

We hypothesize that collagen markers are prognostic tools for segregating patient populations in clinical trials.

First Ecuadorian statement consensus for the evaluation and treatment of osteoporosis

Osteoporosis management has become more relevant as the life expectancy increases. In Ecuador, approximately 19% of adults over 65 years of age have been diagnosed with osteoporosis. There is no national consensus for the management and prevention of the disease being this proposal the first Ecuadorian consensus.

INTRODUCTION

In Ecuador, it is estimated that around 19% of adults over 65 years of age have osteoporosis. Due to the increase in life expectancy in the world population, the evaluation and management of osteoporosis has become more relevant. Currently, there is no national consensus for the management and prevention of the disease. The Ecuadorian Society of Rheumatology presented the project for the elaboration of the first Ecuadorian consensus for the management and prevention of osteoporosis.

METHODS

A panel of experts in multiple areas and extensive experience was invited to participate. The consensus was carried out using the Delphi method. Six working dimensions were created: definition and epidemiology of osteoporosis, fracture risk prediction tools, non-pharmacological treatment, pharmacological treatment, calcium and vitamin D, and glucocorticoid-induced osteoporosis.

RESULTS

The first round was held in December 2021, followed by the second round in February 2022 and the third round in March 2022. The data was shared with the specialists at the end of each round. After three rounds of work, a consensus was reached for the management and prevention of osteoporosis.

CONCLUSION

This is the first Ecuadorian consensus for the management and treatment of postmenopausal osteoporosis.

Clinical monitoring in osteoarthritis: Biomarkers

OBJECTIVE

The purpose of this overview of osteoarthritis (OA) biomarkers is to provide the non-specialist with a toolbox, based on experience acquired by biomarker researchers over many years, to understand biomarkers in general and their use in the OA field.

METHODS

We provide an update on this subject since the OARSI Primer on osteoarthritis (OA) nearly a decade ago.

RESULTS

Since the last update, the importance of molecular biomarkers has been increasingly recognized in the field, but no OA-related biomarkers have been adopted for routine use in clinical practice. The current lack of chondroprotective treatments for OA impairs the assessment, validation and qualification of the potential role of biomarkers as tools for monitoring disease status and patient responses to treatment of OA. Yet there is no lack of an evolving compendium of OA-related biomarkers, ever more fit-for-purpose, that could currently facilitate drug development for OA. We provide an abbreviated update and overview of specific soluble OA-related biomarkers for this new OARSI Primer on OA with OA-relevant examples encompassing the concepts of biomarker nomenclature, qualification, interpretation, measurement, reporting requirements, application to research, drug discovery and clinical care, and future needs for biomarker advancement.

CONCLUSION

Appropriate biomarkers should play a role at all stages of OA diagnosis, prognosis, drug development, and treatment. The future of OA biomarker research and development holds great promise as its foundation is increasingly robust.

Considerations for understanding protein measurements: Identification of formation, degradation and more pathological relevant epitopes

OBJECTIVES

There is a need for precision medicine and an unspoken promise of an optimal approach for identification of the right patients for value-based medicine based on big data. However, there may be a misconception that measurement of proteins is more valuable than measurement of fewer selected biomarkers. In population-based research, variation may be somewhat eliminated by quantity. However, this fascination of numbers may limit the attention to and understanding of the single. This review highlights that protein measurements (with collagens as examples) may mean different things depending on the targeted epitope - formation or degradation of tissues, and even signaling potential of proteins.

DESIGN AND METHODS

PubMed was searched for collagen, neo-epitope, biomarkers.

RESULTS

Ample examples of assays with specific epitopes, either pathological such as HbA1c, or domain specific such as pro-peptides, which total protein arrays would not have identified were evident.

CONCLUSIONS

We suggest that big data may be considered as the funnel of data points, in which most important parameters will be selected. If the technical precision is low or the biological accuracy is limited, and we include suboptimal quality of biomarkers, disguised as big data, we may not be able to fulfill the promise of helping patients searching for the optimal treatment. Alternatively, if the technical precision of the total protein quantification is high, but we miss the functional domains with the most considerable biological meaning, we miss the most important and valuable information of a given protein. This review highlights that measurements of the same protein in different ways may provide completely different meanings. We need to understand the pathological importance of each epitope quantified to maximize protein measurements.

Serological biomarker profiles of rapidly progressive osteoarthritis in tanezumab-treated patients

There is a need for efficacious and safe pain treatments for OA (osteoarthritis). The nerve growth factor (NGF) antibody tanezumab is associated with high efficacy, but when combined with chronic NSAID treatment shows an increased risk of rapidly progressive osteoarthritis (RPOA) in a small group of patients.

AIM

The aim of this study was to phenotype with biochemical biomarkers of bone, cartilage, soft tissue, synovial metabolism OA patients who are at risk of developing RPOA type-2, for both limited and chronic NSAIDs users.

MATERIAL AND METHODS

The dataset consisted of OA patients participating in tanezumab trials who used NSAIDs <90 days (limited NSAID users) or chronic users (NSAIDs ≥90 days) over an average 10 month period. Biomarker data were available for 47 cases (RPOA type-2) and 92 controls. Non-linear and linear multivariable predictive models were developed.

RESULTS

By use of two biomarkers at baseline the receiver operating characteristic (ROC) curve area for RPOA type-2 in limited NSAID users was 71%, [CI] (60-83%). OA subjects with this biomarker phenotype had 8-fold higher confidence interval [CI][(2-33)] relative risk of developing RPOA type-2 as compared to OA patients without this phenotype. The AUC of the model in chronic NSAIDs users based on 5 biomarkers was 78%, [CI](69-88%), with 4-fold [CI (2-6)] relative risk of developing RPOA type-2.

CONCLUSION

In this hypothesis generating and exploratory study, we identified combinations of biomarkers associated with OA patients who develop RPOA type-2, which may be related to the pathology of the RPOA type-2 joint.

Tight control: a new therapeutic strategy in the management of osteoporotic patients

BMD changes in patients under tight control (monitored at 3-month intervals with adjustment of therapy guided by bone turnover markers) and routine management (controlled once a year) were compared. After 1 year, the femoral neck BMD increased significantly in the tight control compared to the routine management group.

INTRODUCTION

We intended to ascertain whether tight control (i.e., follow-up visits and bone turnover markers/BTM/and parathyroid hormone/PTH/monitoring at 3-month intervals) strategy achieves a statistically greater increase in bone mineral density over the observation period than standard follow-up care (i.e., bone densitometry at 1-year intervals, without BTM monitoring).

METHODS

We studied involutional osteoporotic patients newly enrolled into chronic care. One hundred and eleven patients underwent tight control, while another 113 received routine treatment (with follow-up visits scheduled at > 1-year intervals). We compared the changes in bone mineral density reflected by the results of bone mineral density (BMD) measurements of the lumbar spine and of the left femoral neck. Statistical analyses were performed with version 22 of the SPSS software package.

RESULTS

In the group of patients under tight control, baseline and follow-up median BMD values were 0.842/0.881 g/cm² at the L_1-4 vertebrae and 0.745/0.749 g/cm² at the femoral neck. In the group under routine care, the corresponding values were 0.903/0.915 g/cm² and 0.742/0.72 g/cm², respectively. The relative changes of the bone mineral density of the femoral neck was significantly (p = 0.041) higher in patients under tight control than in those receiving routine care; however, BMD changes in the lumbar spine were not statistically different.

CONCLUSION

Our findings suggest that adopting tight control as a new therapeutic strategy might be justified in the osteoporosis management. In fact, a greater improvement of BMD can be achieved by treatment according to these principles.

Correlations between bone turnover markers, serum magnesium and bone mass density in postmenopausal osteoporosis

Introduction

Bone mass density (BMD) is still the gold standard for the diagnosis of osteoporosis, but bone turnover markers (BTMs) can provide helpful information regarding the bone remodeling process. The aim of this study was to determine the correlations between BMD and serum levels of BTMs (tartrate-resistant acid phosphatase-5b [TRAP-5b]), bone-specific alkaline phosphatase (BSAP), estradiol (E₂), and magnesium (Mg^[2+]) ion concentrations in postmenopausal osteoporotic women as compared to healthy postmenopausal subjects.

Materials and methods

The study included 132 women with postmenopausal osteoporosis and 81 healthy postmenopausal women without osteoporosis. Dual-energy X-ray absorptiometry scan assessed BMD at different skeleton sites. Serum levels of E₂, BSAP, and TRAP-5b were measured by enzyme linked immunosorbent assay. Serum levels of Mg⁽²⁺⁾ were determined using the colorimetric spectrometry technique.

Results

Serum levels of BTMs were significantly higher in osteoporotic women than in controls. BSAP has a moderate sensitivity (76.5%) and specificity (84.3%) (cutoff point 21.27 U/L). At a cutoff point of 3.45 U/L, TRAP-5b presented a sensitivity of 86.3% and a higher specificity of 90.6%. Osteoporotic patients showed significantly lower concentrations of serum Mg⁽²⁺⁾ than the control group. Mg⁽²⁺⁾ levels correlated positively with BMD values (r=0.747, P<0.0001). Furthermore, Mg⁽²⁺⁾ concentrations correlated positively with E₂ levels (r=0.684, P<0.0001). Spine BMD correlated negatively with BSAP levels (r=−0.36, P<0.0001).

Conclusion

Our study showed that BMD correlates negatively with BTMs and positively with E₂ and Mg⁽²⁺⁾ levels. TRAP-5b presents a good specificity in identifying patients with postmenopausal osteoporosis.

Tectorigenin inhibits RANKL-induced osteoclastogenesis via suppression of NF-κB signalling and decreases bone loss in ovariectomized C57BL/6

Metabolism of bone is regulated by the balance between osteoblast‐mediated bone formation and osteoclast‐mediated bone resorption. Activation of osteoclasts could lead to osteoporosis. Thus, inhibiting the activity of osteoclasts becomes an available strategy for the treatment of osteoporosis. Tectorigenin is an extract of Belamcanda chinensis In the present study, the anti‐osteoclastogenesis effects of tectorigenin were investigated in vitro and in vivo. The results showed preventive and therapeutic effects of tectorigenin at concentrations of 0, 10, 40, and 80 μmol/L in the maturation and activation of osteoclasts. A signalling study also indicated that tectorigenin treatment reduces activation of NF‐κB signalling in osteoclastogenesis. Animal experiment demonstrated that tectorigenin treatment (1‐10 mg/kg, abdominal injection every 3 days) significantly inhibits bone loss in ovariectomized C57BL/6. Our data suggest that tectorigenin is a potential pharmacological choice for osteoporosis.

Collagen and tissue turnover as a function of age: Implications for fibrosis

BACKGROUND & AIMS

The extracellular matrix (ECM) is the backbone of all tissues. It is a complex grid consisting of multiple structural proteins which each play a vital role for the function and maintenance of normal tissue function. In development and growth, tissue is being formed and elaborated (tissue modeling), while in adult life, tissues are being maintained and remodeled. These processes involve likely different mechanisms. During tissue modeling and remodeling, small fragments of proteins are released into the circulation, where they may be used as biomarkers for tissue turnover. The aim of the study was to investigate ECM turnover in rodents as a function of age.

METHODS

Serum of rats of 1, 2, 3, 4, 5, 6, 10 and 12months of age was profiled for 15 markers of ECM turnover, including: fragments of type I, II, III, IV, V and VI collagen formation (P1NP, P4NP-7S, Pro-C5, Pro-C6) and degradation (C1M, C2M, C2M-beta, C3M, C4M, C5M, C6M); biglycan (BGM) and elastin (ELM7) degradation; and the type I and II collagen telopeptides CTX-I and CTX-II.

RESULTS

Type I and II collagen turnover was up to 93% and 97% downregulated in old (one year) compared to young (one month) old animals (p<0.0001), while type IV and V collagen and biglycan turnover was upregulated 2.5-, 2- and 2-fold, respectively (p<0.0001). Type III and VI collagen and elastin turnover was not influenced significantly by age.

CONCLUSIONS

ECM turnover rates were consistently different in young vs. old animals, up to 30 fold. This appears to be due to body growth, a different ECM composition and a higher regenerative capability of connective tissues in young vs. old animals. These changes have to be accounted for in translational science. Both in measuring serum levels of ECM biomarkers and in the development of therapies to speed up wound healing or inhibit fibrogenesis.

Biochemical markers for assessment of calcium economy and bone metabolism: application in clinical trials from pharmaceutical agents to nutritional products

Nutrition plays an important role in osteoporosis prevention and treatment. Substantial progress in both laboratory analyses and clinical use of biochemical markers has modified the strategy of anti-osteoporotic drug development. The present review examines the use of biochemical markers in clinical research aimed at characterising the influence of foods or nutrients on bone metabolism. The two types of markers are: (i) specific hormonal factors related to bone; and (ii) bone turnover markers (BTM) that reflect bone cell metabolism. Of the former, vitamin D metabolites, parathyroid hormone, and insulin-like growth factor-I indicate responses to variations in the supply of bone-related nutrients, such as vitamin D, Ca, inorganic phosphate and protein. Thus modification in bone remodelling, the key process upon which both pharmaceutical agents and nutrients exert their anti-catabolic or anabolic actions, is revealed. Circulating BTM reflect either osteoclastic resorption or osteoblastic formation. Intervention with pharmacological agents showed that early changes in BTM predicted bone loss and subsequent osteoporotic fracture risk. New trials have documented the influence of nutrition on bone-tropic hormonal factors and BTM in adults, including situations of body-weight change, such as anorexia nervosa, and weight loss by obese subjects. In osteoporosis-prevention studies involving dietary manipulation, randomised cross-over trials are best suited to evaluate influences on bone metabolism, and insight into effects on bone metabolism may be gained within a relatively short time when biochemical markers are monitored.

Future detection and monitoring of diabetes may entail analysis of both β-cell function and volume: how markers of β-cell loss may assist

Disease heterogeneity is as major issue in Type II Diabetes Mellitus (T2DM), and this patient inter-variability might not be sufficiently reflected by measurements of glycated haemoglobin (HbA1c).Β-cell dysfunction and β-cell death are initiating factors in development of T2DM. In fact, β-cells are known vanish prior to the development of T2DM, and autopsy of overt T2DM patients have shown a 60% reduction in β-cell mass.As the decline in β-cell function and mass have been proven to be pathological traits in T2DM, methods for evaluating β-cell loss is becoming of more interest. However, evaluation of β-cell death or loss is currently invasive and unattainable for the vast majority of diabetes patients. Serological markers, reflecting β-cell loss would be advantageous to detect and monitor progression of T2DM. Biomarkers with such capacities could be neo-epitopes of proteins with high β-cell specificity containing post translational modifications. Such tools may segregate T2DM patients into more appropriate treatment groups, based on their β-cell status, which is currently not possible. Presently individuals presenting with adequately elevated levels of both insulin and glucose are classified as T2DM patients, while an important subdivision of those is pending, namely those patients with sufficient β-cell capacity and those without. This may warrant two very different treatment options and patient care paths.Serological biomarkers reflecting β-cell health status may also assist development of new drugs for T2DM and aid physicians in better characterization of individual patients and tailor individual treatments and patient care protocols.

Will posttranslational modifications of brain proteins provide novel serological markers for dementias?

Drug development for dementias is significantly hampered by the lack of easily accessible biomarkers. Fluid biomarkers of dementias provide indications of disease stage, but have little prognostic value, cannot detect early pathological changes, and can only be measured in CSF (cerebrospinal fluid) which significantly limits their applicability. In contrast, imaging based biomarkers can provide indications of probability of disease progression, yet are limited in applicability due to cost, radiation and radio-tracers. These aspects highlight the need for other approaches to the development of biomarkers of dementia, which should focus on not only providing information about pathological changes, but also on being measured easily and reproducibly. For other diseases, focus on development of assays monitoring highly specific protease-generated cleavage fragments of proteins has provided assays, which in serum or plasma have the ability to predict early pathological changes. Proteolytic processing of brain proteins, such as tau, APP, and α-synuclein, is a key pathological event in dementias. Here, we speculate that aiming biomarker development for dementias at detecting small brain protein degradation fragments of generated by brain-derived proteases specifically in blood samples could lead to the development of novel markers of disease progression, stage and importantly of treatment efficacy.