Paget's Disease of Bone

Standard and advanced echocardiographic study of patients with Paget's disease of bone: Evidence of a pagetic heart disease?

BACKGROUND

Paget's disease of the bone (PDB) is a metabolic bone disorder involving one or more skeletal sites. Cardiovascular diseases (CVDs) have been described in patients with PDB but have not been systematically analysed.

OBJECTIVES

This study aimed to compare standard and advanced (speckle-tracking) echocardiographic parameters measured in patients with PDB and controls matched for age, weight, height and history of hypertension but without metabolic bone disorders.

METHODS

This multicentre case-control study included all patients with PDB referred to the Federico II and Siena Universities, Italy, from March 2019 to October 2022. During the same time, we enrolled at least one control for each patient, matched for age, sex, body mass index (BMI) and history of hypertension.

RESULTS

Sixty-nine patients with PDB and 115 healthy controls were enrolled in this study. All patients with PDB were treated with zoledronic acid at the time of diagnosis. Compared with controls, on standard echocardiography, patients with PDB showed a high prevalence of aortic and mitral valve calcifications and/or sclerosis, reduced left ventricular (LV) ejection fraction, stroke volume, cardiac output, increased interventricular septum thickness, posterior wall thickness, LV mass index, relative wall thickness, relative diastolic wall thickness, E/e' ratio and systemic vascular resistance. Using speckle-tracking echocardiography, patients with PDB showed a lower global longitudinal strain and global myocardial work efficiency than controls. There was no relationship between the PDB activity and extent and severity of cardiac abnormalities.

CONCLUSION

Overall, the myocardial function and structure were impaired in patients with PDB. Additionally, PDB was associated with early subclinical myocardial damage.

Treatment of Extraosseous Giant Cell Tumor of Bone and Calcitriol-Mediated Hypercalcemia With Denosumab in Paget Disease

Extraosseous giant cell tumor of bone (GCTB) associated with Paget disease of bone (PDB) is rare. We report a patient aged in their 70s with polyostotic PDB involving the skull, spine, and pelvis, previously treated with bisphosphonates, who presented with symptomatic hypercalcemia (calcium 14.8 mg/dL [3.7 mmol/L]; reference range [RR], 8.6-10.5 mg/dL [2.1-2.6 mmol/L]), kidney injury (creatinine 2.6 mg/dL [230 μmol/L]; RR, 0.4-1.1 mg/dL [35-97 μmol/L]), and a 17.5 cm pelvic mass. Testing showed elevated calcitriol or 1,25-dihydroxyvitamin D (1,25(OH)2D) (57-108 pg/mL [137-259 pmol/L]; RR, 18-72 pg/mL [43-173 pmol/L]), but normal parathyroid hormone and bone-specific alkaline phosphatase (BSAP), arguing against parathyroid autonomy and active osseous PDB. Histopathology showed osteoclast-like giant cells and stromal mononuclear cells without atypia, necrosis, or mitoses. A one-time dose of denosumab 120 mg resulted in normalized calcium (9.0 mg/dL [2.2 mmol/L]) and 1,25(OH)2D (24 pg/mL [57 pmol/L]) and reduced tumor size. Denosumab was continued at a dose of 60 mg every 6 months. After 20 months, calcium and 1,25(OH)2D remained normal, with no tumor regrowth, and BSAP stayed low. This is the first report of 1,25(OH)2D-mediated hypercalcemia in extraosseous GCTB. It responded well to denosumab. Long-term management options are discussed in the context of existing literature.

Epigenetic Regulation of ZNF687 by miR-142a-3p and DNA Methylation During Osteoblast Differentiation and Mice Bone Development and Aging

Zinc finger protein 687 (ZNF687), a transcription factor implicated in osteoblast/osteoclast differentiation and linked to Paget's disease of bone, has unclear mechanisms in bone metabolism. Epigenetic disruptions can affect bone cell activity and contribute to bone-related diseases. This work aimed to elucidate the regulatory role of epigenetics in modulating Zfp687 expression throughout osteoblast differentiation and bone growth/aging in mice. Differentiation of the mouse-derived osteoblast precursor cell line (MC3T3-E1) showed increased expression of osteogenic markers and decreased Zfp687 expression. In the hindlimb bones of C57BL/6J mice, the expression of most bone-forming genes decreased from youth to adulthood, while Zfp687 and Runx2 expression was maintained, being only significantly reduced in old mice in comparison to young mice. Bisulfite sequencing revealed hypomethylation of the Zfp687 promoter during MC3T3-E1 differentiation and bone growth/aging. Bioinformatics predicted miR-142a-3p, miR-122b-5p, and miR-124-3p binding sites in Zfp687 3'UTR, and RT-qPCR analysis showed higher expression of these miRNAs in mature osteoblasts. Transfection of a miR-142-3p mimic reduced luciferase activity in the wildtype Zfp687 3'UTR but not the mutant 3'UTR and downregulated the Zfp687 gene and protein levels. In conclusion, miR-142a-3p directly targets the Zfp687 3'UTR, promoting its downregulation during osteoblastogenesis. Furthermore, DNA methylation does not appear to regulate Zfp687 during osteoblast differentiation or bone development in mice.

Bone sarcomas and cancer predisposition syndromes

Bone sarcomas, constituting less than 1% of malignant neoplasms across all age groups, are rare tumours possibly associated with genetic susceptibility syndromes. This review aims to provide recommendations for the detection of cancer predisposition syndromes associated with bone sarcomas and managing affected patients. Recommendations were formulated by a multidisciplinary working and reviewing group from GROUPOS and SFCE oncogenetic's group, including geneticists, oncologists, and radiologists. For various bone sarcomas including osteosarcomas, chondrosarcomas and Ewing sarcomas, we delineate tumour presentation, management strategies, and follow-up within the context of cancer predisposition syndromes. The inherited predisposition syndrome, associated with germline TP53 variants, known as the Li-Fraumeni syndrome, is the most frequent implicated in osteosarcoma cases. Other cancer predisposition syndromes, such as RB1, RECQ or CDKN2A disorders in osteosarcomas and Ollier and Maffucci diseases in chondrosarcomas, are also recognized. Additionally, we discuss rarer cancer predisposition syndromes associated with bone sarcomas and suggest tailored treatment approaches in some cancer predisposition syndromes to mitigate severe toxicities or secondary oncological events. Furthermore, we emphasize the role of identification somatic molecular variations in identifying constitutional germline variants and describe national and international screening programs, reference networks and molecular tumour boards available for collegial and collaborative management discussion. This comprehensive review provides insights into the intricate interplay between genetic predisposition, tumour biology, and therapeutic interventions in bone sarcoma patients with cancer predisposition syndrome.

Development of Paget's disease of bone in adults inheriting SQSTM1 mutations: a long-term follow-up

In a 2015 study of SQSTM1 mutation carriers who had initial negative bone scintigraphy, we found that the rate of development of Paget's disease of bone (PDB) over 5 yr was low. We report here an additional 8-yr follow-up of this cohort, exploring the hypothesis that the rate of development of PDB would increase as the cohort aged. In the current study, 21 of 24 subjects from 2015 who had a negative bone scintiscan at baseline and at first follow-up, had a repeat scintiscan and measurement of total serum alkaline phosphatase activity. Two subjects with P392L mutations were identified as having PDB (monostotic in one case, 2 bones involved in the other), giving an incidence during this follow-up period of 1 per 87 patient years or 11.9 per 1000 patient years. This was contrary to our hypothesis, as the rate of development had decreased as the cohort aged. When we compared by survival analysis the age at presentation with symptomatic PDB in the older generation, we found that the age of onset was later and disease severity in the affected relatives was markedly less than in their clinically affected parents (p < .001). Our results are in keeping with other recently published studies and the general secular trend in PDB and support the idea that an important environmental-genetic interaction is involved with the development of PDB and that exposure to the putative environmental factor has substantially reduced.

Paget's bone disease in a nonendemic region: Exploring novel therapeutic strategies

Paget's disease of bone (PDB) is a chronic condition causing abnormal bone remodeling, leading to pain, fractures, and complications. A 57-year-old female patient, asymptomatic and devoid of pain, incidentally exhibited elevated levels of alkaline phosphatase. Following a thorough consideration of potential differential diagnoses, the eventual diagnosis established was PDB. We recommended Fosamax (70 mg alendronate tablets) at two tablets twice weekly for 3 months to manage PDB due to patient preference and side effects with intravenous zoledronic acid. Subsequent assessments of alkaline phosphatase levels during follow-up examinations post-treatment revealed a reduction in their values.

From bimodal to unimodal: The transformed incidence of osteosarcoma in the United States

Background

Osteosarcoma is the most common primary bone malignancy. It has classically been described as having a bimodal incidence by age. We sought to identify whether the bimodal incidence distribution still exists for osteosarcoma using the SEER and NIS databases.

Methods

Incidence rates of primary osteosarcoma between 2000-2021 were analyzed by age at diagnosis, year of occurrence, sex, and tumor site from the SEER Research Data, 17 Registries, Nov 2023 Sub (2000-2021). The incidence of cases in 35-64 year-olds and 65 and above was compared statistically to determine if there is an increased incidence in the later ages. Incidence of tumors of the long bones of the lower limbs from the NIS discharge database 2012-2019 was also analyzed for comparison.

Results

Overall, 5,129 cases of osteosarcoma were reported in the SEER database. Across the 22 calendar year span, a consistent first peak appeared in the second decade of life. There was no consistent second peak in the 35+ age group. There were 86,100 discharges with long bone tumors analyzed in the NIS data which exhibited nearly identical patterns.

Conclusions

Our analysis shows that the incidence of osteosarcoma is no longer bimodally distributed but rather unimodally distributed.

Regulation of bone homeostasis: signaling pathways and therapeutic targets

As a highly dynamic tissue, bone is continuously rebuilt throughout life. Both bone formation by osteoblasts and bone resorption by osteoclasts constitute bone reconstruction homeostasis. The equilibrium of bone homeostasis is governed by many complicated signaling pathways that weave together to form an intricate network. These pathways coordinate the meticulous processes of bone formation and resorption, ensuring the structural integrity and dynamic vitality of the skeletal system. Dysregulation of the bone homeostatic regulatory signaling network contributes to the development and progression of many skeletal diseases. Significantly, imbalanced bone homeostasis further disrupts the signaling network and triggers a cascade reaction that exacerbates disease progression and engenders a deleterious cycle. Here, we summarize the influence of signaling pathways on bone homeostasis, elucidating the interplay and crosstalk among them. Additionally, we review the mechanisms underpinning bone homeostatic imbalances across diverse disease landscapes, highlighting current and prospective therapeutic targets and clinical drugs. We hope that this review will contribute to a holistic understanding of the signaling pathways and molecular mechanisms sustaining bone homeostasis, which are promising to contribute to further research on bone homeostasis and shed light on the development of targeted drugs.

Diagnosis and treatment of Paget's disease of bone: position paper from the Italian Society of Osteoporosis, Mineral Metabolism and Skeletal Diseases (SIOMMMS)

INTRODUCTION

Paget's disease of bone is a focal skeletal disorder causing bone deformities and impairing bone quality. Despite the prevalence of asymptomatic cases is increasing, the progression of the disease can lead to invalidating complications that compromise the quality of life. Doubts on clinical and therapeutic management aspects exist, although beneficial effects of antiresorptive drugs, particularly bisphosphonates are known. However, limited information is available from randomized controlled trials on the prevention of disease complications so that somewhat contrasting positions about treatment indications between expert panels from the main scientific societies of metabolic bone diseases exist. This task force, composed by expert representatives appointed by the Italian Society of Osteoporosis, Mineral Metabolism and Skeletal Diseases and members of the Italian Association of Paget's disease of bone, felt the necessity for more specific and up to date indications for an early diagnosis and clinical management.

METHODS

Through selected key questions, we propose evidence-based recommendations for the diagnosis and treatment of the disease. In the lack of good evidence to support clear recommendations, available information from the literature together with expert opinion of the panel was used to provide suggestions for the clinical practice.

RESULTS AND CONCLUSION

Description of the evidence quality and support of the strength of the statements was provided on each of the selected key questions. The diagnosis of PDB should be mainly based on symptoms and the typical biochemical and radiological features. While treatment is mandatory to all the symptomatic cases at diagnosis, less evidence is available on treatment indications in asymptomatic as well as in previously treated patients in the presence of biochemical recurrence. However, given the safety and long-term efficacy of potent intravenous bisphosphonates such as zoledronate, a suggestion to treat most if not all cases at the time of diagnosis was released.

Paget Disease of Bone Harboring Bone Metastatic Neuroendocrine Cancer: A Case Report

In this case report, we describe an uncommon case of neuroendocrine cancer of unknown origin began with cauda equina syndrome in a patient affected by Paget disease of bone (PDB). A 76-year-old man with diagnosis of PDB, without history of pain or bone deformity, developed sudden severe low back pain. Bone alkaline phosphatase was increased and MRI and whole-body scintigraphy confirmed the localization of the disease at the third vertebra of the lumbar spine. Treatment with Neridronic Acid was started, but after only 2 weeks of therapy anuria and bowel occlusion occurred together with lower limb weakness and walking impairment. Cauda equina syndrome consequent to spinal stenosis at the level of L2-L3 was diagnosed after admission to Emergency Department and the patient underwent neurosurgery for spinal medulla decompression. The histologic results showed a complete subversion of bone structure in neoplastic tissue, consistent with metastatic neuroendocrine carcinoma of unknown origin. In conclusion, low back pain in the elderly may require deep investigation to individuate rare diseases. In asymptomatic patients with apparently stable PDB, the sudden appearance of pain or neurologic symptoms may alert the clinician for the possibility of other superimposing diseases, like bone metastases.

Subchondral osteoclasts and osteoarthritis: new insights and potential therapeutic avenues

Osteoarthritis (OA) is the most common joint disease, and good therapeutic results are often difficult to obtain due to its complex pathogenesis and diverse causative factors. After decades of research and exploration of OA, it has been progressively found that subchondral bone is essential for its pathogenesis, and pathological changes in subchondral bone can be observed even before cartilage lesions develop. Osteoclasts, the main cells regulating bone resorption, play a crucial role in the pathogenesis of subchondral bone. Subchondral osteoclasts regulate the homeostasis of subchondral bone through the secretion of degradative enzymes, immunomodulation, and cell signaling pathways. In OA, osteoclasts are overactivated by autophagy, ncRNAs, and Rankl/Rank/OPG signaling pathways. Excessive bone resorption disrupts the balance of bone remodeling, leading to increased subchondral bone loss, decreased bone mineral density and consequent structural damage to articular cartilage and joint pain. With increased understanding of bone biology and targeted therapies, researchers have found that the activity and function of subchondral osteoclasts are affected by multiple pathways. In this review, we summarize the roles and mechanisms of subchondral osteoclasts in OA, enumerate the latest advances in subchondral osteoclast-targeted therapy for OA, and look forward to the future trends of subchondral osteoclast-targeted therapies in clinical applications to fill the gaps in the current knowledge of OA treatment and to develop new therapeutic strategies.

Znf687 recruits Brd4-Smrt complex to regulate gfi1aa during neutrophil development

Neutrophils are key component of the innate immune system in vertebrates. Diverse transcription factors and cofactors act in a well-coordinated manner to ensure proper neutrophil development. Dysregulation of the transcriptional program triggering neutrophil differentiation is associated with various human hematologic disorders such as neutropenia, neutrophilia, and leukemia. In the current study we show the zinc finger protein Znf687 is a lineage-preferential transcription factor, whose deficiency leads to an impaired neutrophil development in zebrafish. Mechanistically, Znf687 functions as a negative regulator of gfi1aa, a pivotal modulator in terminal granulopoiesis, to regulate neutrophil maturation. Moreover, we found BRD4, an important epigenetic regulator, directly interacts with ZNF687 in neutrophils. Deficiency of brd4 results in similar defective neutrophil development as observed in znf687 mutant zebrafish. Biochemical and genetic analyses further reveal that instead of serving as a canonical transcriptional coactivator, Brd4 directly interacts and bridges Znf687 and Smrt nuclear corepressor on gfi1aa gene's promoter to exert transcription repression. In addition, the ZNF687-BRD4-SMRT-GFI1 transcriptional regulatory network is evolutionary conserved in higher vertebrate. Overall, our work indicates Znf687 and Brd4 are two novel master regulators in promoting terminal granulopoiesis.

Metabolic bone disorders and the promise of marine osteoactive compounds

Metabolic bone disorders and associated fragility fractures are major causes of disability and mortality worldwide and place an important financial burden on the global health systems. These disorders result from an unbalance between bone anabolic and resorptive processes and are characterized by different pathophysiological mechanisms. Drugs are available to treat bone metabolic pathologies, but they are either poorly effective or associated with undesired side effects that limit their use. The molecular mechanism underlying the most common metabolic bone disorders, and the availability, efficacy, and limitations of therapeutic options currently available are discussed here. A source for the unmet need of novel drugs to treat metabolic bone disorders is marine organisms, which produce natural osteoactive compounds of high pharmaceutical potential. In this review, we have inventoried the marine osteoactive compounds (MOCs) currently identified and spotted the groups of marine organisms with potential for MOC production. Finally, we briefly examine the availability of in vivo screening and validation tools for the study of MOCs.

Differentiation of osteoblasts: the links between essential transcription factors

Osteoblasts, cells derived from mesenchymal stem cells (MSCs) in the bone marrow, are cells responsible for bone formation and remodeling. The differentiation of osteoblasts from MSCs is triggered by the expression of specific genes, which are subsequently controlled by pro-osteogenic pathways. Mature osteoblasts then differentiate into osteocytes and are embedded in the bone matrix. Dysregulation of osteoblast function can cause inadequate bone formation, which leads to the development of bone disease. Various key molecules are involved in the regulation of osteoblastogenesis, which are transcription factors. Previous studies have heavily examined the role of factors that control gene expression during osteoblastogenesis, both in vitro and in vivo. However, the systematic relationship of these transcription factors remains unknown. The involvement of ncRNAs in this mechanism, particularly miRNAs, lncRNAs, and circRNAs, has been shown to influence transcriptional factor activity in the regulation of osteoblast differentiation. Here, we discuss nine essential transcription factors involved in osteoblast differentiation, including Runx2, Osx, Dlx5, β-catenin, ATF4, Ihh, Satb2, and Shn3. In addition, we summarize the role of ncRNAs and their relationship to these essential transcription factors in order to improve our understanding of the transcriptional regulation of osteoblast differentiation. Adequate exploration and understanding of the molecular mechanisms of osteoblastogenesis can be a critical strategy in the development of therapies for bone-related diseases.Communicated by Ramaswamy H. Sarma.

Genetic Screening of ZNF687 and PFN1 in a Paget's Disease of Bone Cohort Indicates an Important Role for the Nuclear Localization Signal of ZNF687

Paget's disease of bone (PDB) is a common, late-onset bone disorder, characterized by focal increases of bone turnover that can result in bone lesions. Heterozygous pathogenic variants in the Sequestosome 1 (SQSTM1) gene are found to be the main genetic cause of PDB. More recently, PFN1 and ZNF687 have been identified as causal genes in patients with a severe, early-onset, polyostotic form of PDB, and an increased likelihood to develop giant cell tumors. In our study, we screened the coding regions of PFN1 and ZNF687 in a Belgian PDB cohort (n = 188). In the PFN1 gene, no variants could be identified, supporting the observation that variants in this gene are extremely rare in PDB. However, we identified 3 non-synonymous coding variants in ZNF687. Interestingly, two of these rare variants (p.Pro937His and p.Arg939Cys) were clustering in the nuclear localization signal of the encoded ZNF687 protein, also harboring the p.Pro937Arg variant, a previously reported disease-causing variant. In conclusion, our findings support the involvement of genetic variation in ZNF687 in the pathogenesis of classical PDB, thereby expanding its mutational spectrum.

Paget's Disease of the Bone and Lynch Syndrome: An Exceptional Finding

Our objective is to present an exceptional case of a patient diagnosed with Paget's disease of the bone (PDB) while being confirmed with Lynch syndrome (LS). A 44-year-old woman was admitted for progressive pain in the left forearm 2 years ago, and was partially relieved since admission by non-steroidal anti-inflammatory drugs. Suggestive imaging findings and increased blood bone turnover markers helped the diagnosis of PDB. She was offered zoledronate 5 mg. She had two more episodes of relapse, and a decision of new medication was taken within the following years (a second dose of zoledronate, as well as denosumab 60 mg). Her family history showed PDB (mother) and colorectal cancer (father). Whole exome sequencing was performed according to the manufacturer's standard procedure (Ion AmpliSeq™ Exome RDY S5 Kit). A heterozygous pathogenic variant in the SQSTM1 gene (c.1175C>T, p.Pro392Leu) was confirmed, consistent with the diagnosis of PDB. Additionally, a heterozygous pathogenic variant of MSH2 gene (c.2634+1G>T) was associated with LS. The patient's first-degree relatives (her brother, one of her two sisters, and her only daughter) underwent specific genetic screening and found negative results, except for her daughter, who tested positive for both pathogenic variants while being clinically asymptomatic. The phenotype influence of either mutation is still an open issue. To our current knowledge, no similar case has been published before. Both genetic defects that led to the two conditions appeared highly transmissible in the patient's family. The patient might have an increased risk of osteosarcoma and chondrosarcoma, both due to PDB and LS, and a review of the literature was introduced in this particular matter. The phenotypic expression of the daughter remains uncertain and is yet to be a lifelong follow-up as the second patient harbouring this unique combination of gene anomalies.

Paget's disease: a review of the epidemiology, etiology, genetics, and treatment

Paget's disease of bone (PDB) is the second most prevalent metabolic bone disorder worldwide, with a prevalence rate of 1.5%-8.3%. It is characterized by localized areas of accelerated, disorganized, and excessive bone production and turnover. Typically, PDB develops in the later stages of life, particularly in the late 50s, and affects men more frequently than women. PDB is a complex disease influenced by both genetic and environmental factors. PDB has a complex genetic basis involving multiple genes, with SQSTM1 being the gene most frequently associated with its development. Mutations affecting the UBA domain of SQSTM1 have been detected in both familial and sporadic PDB cases, and these mutations are often associated with severe clinical expression. Germline mutations in other genes such as TNFRSF11A, ZNF687 and PFN1, have also been associated with the development of the disease. Genetic association studies have also uncovered several PDB predisposing risk genes contributing to the disease pathology and severity. Epigenetic modifications of genes involved in bone remodelling and regulation, including RANKL, OPG, HDAC2, DNMT1, and SQSTM1, have been implicated in the development and progression of Paget's disease of bone, providing insight into the molecular basis of the disease and potential targets for therapeutic intervention. Although PDB has a tendency to cluster within families, the variable severity of the disease across family members, coupled with decreasing incidence rates, indicates that environmental factors may also play a role in the pathophysiology of PDB. The precise nature of these environmental triggers and how they interact with genetic determinants remain poorly understood. Fortunately, majority of PDB patients can achieve long-term remission with an intravenous infusion of aminobisphosphonates, such as zoledronic acid. In this review, we discuss aspects like clinical characteristics, genetic foundation, and latest updates in PDB research.

Drug treatment strategies for Paget's disease: relieving pain and preventing progression

INTRODUCTION

Paget's disease of bone (PDB) is a focal bone disorder caused by a marked dysregulation of osteoblasts and osteoclasts in basic multicellular units, leading to abnormal and disorganized deposition of collagen fibers (the so-called "woven bone"). Therefore, pagetic bones are increased in size, and at increased risk for bone pain, deformities, fractures, osteoarthritis, and, more rarely, neoplastic degeneration.

AREAS COVERED

In this review we revise the available information concerning the pharmacological treatment of PDB.

EXPERT OPINION

PDB progresses slowly within the affected skeletal sites and, if untreated, often leads to bone overgrowth, with bone pain, deformity and a likely increased risk of complications. Thus, the primary goal of treatment is the restoration of a normal bone turnover, in order to relieve bone pain or other symptoms and possibly prevent the complications. PDB long remained a poorly treatable disorder until the discovery of antiresorptive agents such as calcitonin first and bisphosphonates (BPs) later. With the recent development of potent intravenous BPs like zoledronate, allowing a better control of disease activity over the long term with a single infusion, has contributed to a marked improvement of the clinical management of this invalidating disorder.

Regulation of human ZNF687, a gene associated with Paget's disease of bone

Mutations in Zinc finger 687 (ZNF687) were associated with Paget's disease of bone (PDB), a disease characterized by increased bone resorption and excessive bone formation. It was suggested that ZNF687 plays a role in bone differentiation and development. However, the mechanisms involved in ZNF687 regulation remain unknown. This study aimed to obtain novel knowledge regarding ZNF687 transcriptional and epigenetic regulation. Through in silico analysis, we hypothesized three ZNF687 promoter regions located upstream exon 1 A, 1B, and 1 C and denominated promoter regions 1, 2, and 3, respectively. Their functionality was confirmed by luciferase activity assays and positive/negative regulatory regions were identified using promoter deletions constructs. In silico analysis revealed a high density of CpG islands in these promoter regions and in vitro methylation suppressed promoters' activity. Using bioinformatic approaches, bone-associated transcription factor binding sites containing CpG dinucleotides were identified, including those for NFκB, PU.1, DLX5, and SOX9. By co-transfection in HEK293 and hFOB cells, we found that DLX5 specifically activated ZNF687 promoter region 1, and its methylation impaired DLX5-driven promoter stimulation. NFκB repressed and activated promoter regions 1 and 2, respectively, and these activities were affected by methylation. PU.1 induced ZNF687 promoter region 1 which was affected by methylation. SOX9 differentially regulated ZNF687 promoters in HEK293 and hFOB cells that were impaired after methylation. In conclusion, this study provides novel insights into ZNF687 regulation by demonstrating that NFκB, PU.1, DLX5, and SOX9 are regulators of ZNF687 promoters, and DNA methylation influences their activity. The contribution of the dysregulation of these mechanisms in PDB should be further elucidated.

Updates on Paget's Disease of Bone

Paget's disease of the bone is a prevalent bone disease characterized by disorganized bone remodeling; however, it is comparatively uncommon in East Asian countries, including China, Japan, and Korea. The exact cause still remains unknown. In genetically susceptible individuals, environmental triggers such as paramyxoviral infections are likely to cause the disease. Increased osteoclast activity results in increased bone resorption, which attracts osteoblasts and generates new bone matrix. Fast bone resorption and formation lead to the development of disorganized bone tissue. Increasing serum alkaline phosphatase or unique radiographic lesions may serve as the diagnostic indicators. Common symptoms include bone pain, bowing of the long bones, an enlarged skull, and hearing loss. The diagnosis is frequently confirmed by radiographic and nuclear scintigraphy of the bone. Further, bisphosphonates such as zoledronic acid and pamidronate are effective for its treatment. Moreover, biochemical monitoring is superior to the symptoms as a recurrence indicator. This article discusses the updates of Paget's disease of bone with a clinical case.

The potential for over diagnosis of Paget's disease of bone using macroscopic analysis

OBJECTIVE

This study explores the validity of Paget's disease of bone (PDB) reported in unpublished skeletal reports, based on macroscopic analysis alone.

MATERIALS

The high prevalence of 'suspected' Paget's disease (10.7%) in an early modern sample from St John's the Evangelist Church in Redhill, Surrey is reassessed.

METHODS

Signs of PDB were examined in 53 well-preserved adults aged 35 + years using macroscopic, radiographic and histological techniques.

RESULTS

Macroscopic features of PDB were identified in 8 individuals (15%), with 5 individuals later rejected using radiography. Two individuals showed classic radiographic features of PDB, with a third presenting possible features in radiography (5.7%). These three cases were confirmed by histological analysis.

CONCLUSIONS

PDB should not be suggested as a single diagnosis in cases of bone hypertrophy without confirmation using radiography.

SIGNIFICANCE

The growing popularity of 'big data' projects and limited collections access means that unpublished cases of PDB are often included in large scale analyses, impacting our understanding of the evolution of this disease. Using macroscopic analysis alone leads to overdiagnosis. Histological analysis is unnecessary when radiographic features are present, but provides a useful diagnostic step in long bones in advanced cases of PBD.

LIMITATIONS

The radiographic sample in this study was limited to three individuals.

SUGGESTIONS FOR FURTHER RESEARCH

The conclusion that radiography alone can be used to identify PDB in archaeological cases merits further research on a larger number of cases.

Update on the pathogenesis and genetics of Paget’s disease of bone

Studies over the past two decades have led to major advances in the pathogenesis of Paget’s disease of bone (PDB) and particularly on the role of genetic factors. Germline mutations of different genes have been identified, as a possible cause of this disorder, and most of the underlying pathways are implicated in the regulation of osteoclast differentiation and function, whereas other are involved in cell autophagy mechanisms. In particular, about 30 different germline mutations of the Sequestosome 1 gene (SQSTM1) have been described in a significant proportion of familial and sporadic PDB cases. The majority of SQSTM1 mutations affect the ubiquitin-binding domain of the protein and are associated to a more severe clinical expression of the disease. Also, germline mutations in the ZNF687 and PFN1 genes have been associated to severe, early onset, polyostotic PDB with increased susceptibly to neoplastic degeneration, particularly giant cell tumor. Mutations in the VCP (Valosin Containing Protein) gene cause the autosomal dominant syndrome “Inclusion Body Myopathy, PDB, Fronto-temporal Dementia,” characterized by pagetic manifestations, associated with myopathy, amyotrophic lateral sclerosis and fronto-temporal dementia. Moreover, germline mutations in the TNFRSF11A gene, which encodes for RANK, were associated with rare syndromes showing some histopathological, radiological, and clinical overlap with PDB and in two cases of early onset PDB-like disease. Likewise, genome wide association studies performed in unrelated PDB cases identified other potential predisposition genes and/or susceptibility loci. Thus, it is likely that polygenic factors are involved in the PDB pathogenesis in many individuals and that modifying genes may contribute in refining the clinical phenotype. Moreover, the contribution of somatic mutations of SQSTM1 gene and/or epigenetic mechanisms in the pathogenesis of skeletal pagetic abnormalities and eventually neoplastic degeneration, cannot be excluded. Indeed, clinical and experimental observations indicate that genetic susceptibility might not be a sufficient condition for the clinical development of PDB without the concomitant intervention of viral infection, in primis paramixoviruses, and/or other environmental factors (e.g., pesticides, heavy metals or tobacco exposure), at least in a subset of cases. This review summarizes the most important advances that have been made in the field of cellular and molecular biology PDB over the past decades.

Spinal Paget's disease with bilevel cord compression and ischemic non-compressive myelopathy treated with zoledronic acid

Cord compression and ischemic non-compressive myelopathy are a complication of spinal Paget's disease (SPD). SPD usually touches a single spine level. We report an unusual case with bilevel spinal cord compression and dysfunction which was medically treated due to resolution of the vascular steal syndrome.

Profilin-1 negatively controls osteoclast migration by suppressing the protrusive structures based on branched actin filaments

BACKGROUND

Profilin-1 (Pfn1), an evolutionarily conserved actin-binding protein, is an important regulator of the cytoskeleton. We previously reported the osteoclast-specific Pfn1-conditional knockout (cKO) mice had postnatal osteolytic phenotype with craniofacial and long-bone deformities associated with increased migration of cultured osteoclasts. We hypothesized the increased cellular processes structured with branched actin filaments may underlies the mechanism of increased bone resorption in these mutant mice.

MATERIALS AND METHODS

The morphological structure and cell migration of the cultured osteoclasts were analyzed using fluorescent microscopy and time-lapse image capturing. Fractional migration distances, as well as the index of protrusive structures (%-PB) that evaluates relative border length of the protrusion were compared between the cells from control and Pfn1-cKO mice.

RESULTS

Time-lapse image analysis showed that %-PB was significantly larger in Pfn1-cKO osteoclasts. In addition, the fractional migration distance was positively correlated with the index. When the branched actin filament organization was suppressed by chemical inhibitors, the osteoclast migration was declined. Importantly, the suppression was more extensive in Pfn1-cKO than in control osteoclasts.

CONCLUSION

Our results indicated the causative involvement of the increased branched actin filament formation at least in part for their excessive migration. Our findings provide a mechanistic rationale for testing novel therapeutic approaches targeting branched actin filaments in osteolytic disorders.

Identifying treponemal disease in early East Asia

Objectives

Historic records suggest that a virulent form of treponematosis, sexually transmitted syphilis was introduced to Asia from Europe by the da Gama crew, who landed in India in 1498. Our objective is to assess the gross pathology of human skeletal remains from the Tang dynasty of China to test the presence of treponemal infection in East Asia before 1498. We interpret this paleopathological evidence in the context of site ecology and sociocultural changes during the Tang dynasty.

Materials and methods

We examined the gross pathology of 1598 human skeletons from Xingfulindai (AD 618 to AD 1279) archeological site located on the Central Plain of China. Using the modified diagnostic criteria defined by Hackett's classical work, we classify the pathology as consistent, strongly suggestive, or pathognomonic for treponemal infection.

Results

Twelve adult individuals from Xingfulindai had bone lesions suggestive of systemic pathology. Two of these individuals displayed a combination of lesion patterns pathognomonic of treponemal disease and one had lesions consistent with treponematosis. The radiocarbon dates for the bone samples from these skeletons place them before AD 1200.

Conclusions

The location of Xingfulindai in a continental climatic zone is not typical for yaws and bejel ecology, because these strains occur in the tropics, or in hot, dry environments, respectively. The urban setting, where there is documented evidence for increased interaction between multiple ethnic groups and a developed institution of courtesans during the Tang dynasty, favors sexually transmitted syphilis as the more likely diagnosis. This study supports an earlier spread of syphilis to China than 1498.

Impact of the Endocannabinoid System on Bone Formation and Remodeling in p62 KO Mice

Several studies have shown that the G-protein coupled cannabinoid receptor CB2 and its interaction partner p62 are molecularly involved in bone remodeling processes. Pharmacological activation of the CB2 receptor enhanced bone volume in postmenopausal osteoporosis and arthritis models in rodents, whereas knockout or mutation of the p62 protein in aged mice led to Paget’s disease of bone-like conditions. Studies of pharmacological CB2 agonist effects on bone metabolism in p62 KO mice have not been performed to date. Here, we assessed the effect of the CB2-specific agonist JWH133 after a short-term (5 days in 3-month-old mice) or long-term (4 weeks in 6-month-old mice) treatment on structural, dynamic, and cellular bone morphometry obtained by μCT of the femur and histomorphometry of the vertebral bodies in p62 KO mice and their WT littermates in vivo. A genotype-independent stimulatory effect of CB2 on bone formation, trabecular number, and trabecular thickness after short-term treatment and on tissue mineral density after long-term treatment was detected, indicating a weak osteoanabolic function of this CB2 agonist. Moreover, after short-term systemic CB2 receptor activation, we found significant differences at the cellular level in the number of osteoblasts and osteoclasts only in p62 KO mice, together with a weak increase in trabecular number and a decrease in trabecular separation. Long-term treatment showed an opposite JWH133 effect on osteoclasts in WT versus p62 KO animals and decreased cortical thickness only in treated p62 KO mice. Our results provide new insights into CB2 receptor signaling in vivo and suggest that CB2 agonist activity may be regulated by the presence of its macromolecular binding partner p62.

The Paget's disease of bone risk gene PML is a negative regulator of osteoclast differentiation and bone resorption

Paget's disease of bone (PDB) is characterized by focal increases in bone remodelling. Genome-wide association studies identified a susceptibility locus for PDB tagged by rs5742915, which is located within the PML gene. Here, we have assessed the candidacy of PML as the predisposing gene for PDB at this locus. We found that the PDB-risk allele of rs5742915 was associated with lower PML expression and that PML expression in blood cells from individuals with PDB was lower than in controls. The differentiation, survival and resorptive activity of osteoclasts prepared from Pml-/- mice was increased compared with wild type. Furthermore, the inhibitory effect of IFN-γ on osteoclast formation from Pml-/- was significantly blunted compared with wild type. Bone nodule formation was also increased in osteoblasts from Pml-/- mice when compared with wild type. Although microCT analysis of trabecular bone showed no differences between Pml-/- mice and wild type, bone histomorphometry showed that Pml-/- mice had high bone turnover with increased indices of bone resorption and increased mineral apposition rate. These data indicate that reduced expression of PML predisposes an individual to PDB and identify PML as a novel regulator of bone metabolism. This article has an associated First Person interview with the first author of the paper.

Long-Term Efficacy of Intensive Zoledronate Therapy and Predictors of Retreatment in Paget's Disease of Bone

Despite the current debate on the best therapeutic approach, i.e. symptomatic vs intensive strategy, one zoledronate (Zol) infusion is effective in most patients with Paget's disease of bone (PDB), whereas few need retreatment, whose predictors are not well established. We aimed to evaluate long-term efficacy of intensive Zol therapy and predictors of retreatment in PDB. Pagetic complications, clinical and biochemical response to Zol together with frequency of retreatment were retrospectively assessed in forty-seven PDB patients (age, mean ± SD: 72.5 ± 8.9 years, M/F: 24/23; symptomatic/asymptomatic: 16/31). Statistical analysis for retreatment prediction were based on Mann-Whitney U test, Pearson's Χ2 and ROC curve analysis. During seven-year follow-up, all patients achieved pain relief and only one underwent arthroplasty. Bone alkaline phosphatase (BAP) detected three non-responder (6%) and six relapsing (13%) patients needing retreatment. Retreated patients had less old age (66.1 ± 11.2 vs 74.0 ± 7.7 years), higher frequency of polyostotic disease (78% vs 40%) and higher baseline (96.5 ± 24.8 vs 44.9 ± 27.7 mcg/l) and post-Zol nadir BAP levels (24.7 ± 24.1 vs 8.1 ± 4.1 mcg/l) than patients treated once (p < 0.05 for all comparisons). In multivariate analysis both serum baseline and post-Zol nadir BAP significantly predicted retreatment (OR 1.09, 95%CI 1.01-1.17 and 1.29, 1.03-1.62, respectively), with ROC curve analysis showing the greatest accuracies for threshold values of 75.6 and 9.9 mcg/l (sensitivity 88 and 90%, specificity 94 and 86%, AUC 0.92 and 0.93, respectively). Our data in mostly asymptomatic, metabolically active PDB patients treated with intensive Zol therapy show a negligible incidence of pagetic complications and long-term optimal disease control, with BAP being the best predictor of retreatment.

Genetic Determinants of Paget's Disease of Bone

PURPOSE OF REVIEW

To provide an overview of the role of genes and loci that predispose to Paget's disease of bone and related disorders.

RECENT FINDINGS

Studies over the past ten years have seen major advances in knowledge on the role of genetic factors in Paget's disease of bone (PDB). Genome wide association studies have identified six loci that predispose to the disease whereas family based studies have identified a further eight genes that cause PDB. This brings the total number of genes and loci implicated in PDB to fourteen. Emerging evidence has shown that a number of these genes also predispose to multisystem proteinopathy syndromes where PDB is accompanied by neurodegeneration and myopathy due to the accumulation of abnormal protein aggregates, emphasising the importance of defects in autophagy in the pathogenesis of PDB. Genetic factors play a key role in the pathogenesis of PDB and the studies in this area have identified several genes previously not suspected to play a role in bone metabolism. Genetic testing coupled to targeted therapeutic intervention is being explored as a way of halting disease progression and improving outcome before irreversible skeletal damage has occurred.

Effects of Bisphosphonate Treatment on Circulating Lipid and Glucose Levels in Patients with Metabolic Bone Disorders

Bisphosphonates are the first-choice treatment of osteoporosis and Paget's disease of bone. Among the bisphosphonates, the non-amino-bisphosphonates, such as clodronic acid, are intracellular converted into toxic analogues of ATP and induce cellular apoptosis whereas the amino-bisphosphonates, such as zoledronic acid, inhibit the farnesyl-diphosphate-synthase, an enzyme of the mevalonate pathway. This pathway regulates cholesterol and glucose homeostasis and is a target for statins. In this retrospective cohort study, we evaluated the effects of an intravenous infusion of zoledronic acid (5 mg) or clodronic acid (1500 mg) on blood lipid (i.e. total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol and triglycerides) and glucose levels in patients with osteoporosis and Paget's disease of bone. All patients were evaluated before, 1 and 6 months after bisphosphonate treatment. Pagetic and osteoporotic patients treated with zoledronic acid showed a significant reduction in glucose and atherogenic lipids during follow-up whereas these phenomena were not observed after clodronic treatment. The effect on circulating lipid levels was similar in naïve and re-treated Pagetic patients. Zoledronic acid treatment was associated with a reduction in blood glucose and atherogenic lipids in patients with metabolic bone disorders. The extent of change was similar to that obtained with the regular assumption of a low-intensity statin. Further studies are warranted to better evaluate the clinical implications of these observations.

Paget’s disease of bone: Report of 11 cases

BACKGROUND

Paget’s disease of bone (PDB) is a rare metabolic bone disease in China and is characterized by increased bone resorption and disorganized bone formation. The main clinical symptoms of PDB are focal or multiple bone pain and deformity with high disability. The disease has high missed diagnosis and misdiagnosis rates. This report summarizes the clinical manifestations, imaging and pathological features, and treatments of 11 patients with PDB at our hospital from 1993 to 2020 in order to improve the recognition and prognosis of PDB.

CASE SUMMARY

There were eight male and three female patients whose average age was 48.7 ± 11.0 years with a PDB course of 1-16 years. Nine patients had bone pain and bone deformities in different parts of the body, the majority of which involved the long bones. Laboratory examinations revealed elevated serum alkaline phosphatase (ALP) in all patients with an average of 618 ± 460 IU/L (normal range 0-130 IU/L), and serum calcium and phosphorus levels were in the normal range. Imageology showed that osteolysis was usually combined with osteosclerosis and/or bone deformities in single or multiple bones. ^99mTc-methylene diphosphonate bone scintigraphy revealed increased radionuclide uptake in the bone lesions. Six patients underwent bone tissue biopsy, and the typical pathological changes were a mosaic structure of the bone trabeculae with irregularly arranged cement lines and multinuclear osteoclasts. Ten of the 11 patients were effectively treated with bisphosphonates.

CONCLUSION

Early diagnosis of the rare disease PDB can be made through elevated ALP levels and typical presentations on bone X-ray and from bone tissue biopsy.

Tissue Engineering Through 3D Bioprinting to Recreate and Study Bone Disease

The applications of 3D bioprinting are becoming more commonplace. Since the advent of tissue engineering, bone has received much attention for the ability to engineer normal bone for tissue engraftment or replacement. While there are still debates on what materials comprise the most durable and natural replacement of normal tissue, little attention is given to recreating diseased states within the bone. With a better understanding of the cellular pathophysiology associated with the more common bone diseases, these diseases can be scaled down to a more throughput way to test therapies that can reverse the cellular pathophysiology. In this review, we will discuss the potential of 3D bioprinting of bone tissue in the following disease states: osteoporosis, Paget's disease, heterotopic ossification, osteosarcoma, osteogenesis imperfecta, and rickets disease. The development of these 3D bioprinted models will allow for the advancement of novel therapy testing resulting in possible relief to these chronic diseases.

Paget's Disease of the Bone: Patterns of Referral to Secondary Care Following Diagnosis on X-rays

Paget's disease of bone (PDB) is the second commonest metabolic bone disorder in the UK after osteoporosis and is both underdiagnosed and undertreated. PDB is often found incidentally on plain X-rays. There is effective treatment so identification of affected individuals is important. The aim was to conduct an audit to determine what proportion of individuals with X-ray evidence of PDB were referred to secondary care. A retrospective audit of X-rays reports in men and women over 55 years of age was undertaken over 18 months searching for the key word "Paget's." The images of possible cases were reviewed and the presence of PDB confirmed. The proportion already known to secondary care was determined and those that had had isotope bone scans and treatment. Data recorded included site of lesion, age, gender, level of total alkaline phosphatase (ALP) and complications. A total of 68,873 X-rays were screened and 43 cases found. Pelvic images had the highest proportion of positive findings at 0.2% and 65% of the cases. 74% had not been referred to secondary care. The mean age was 86.7 years (range 65-95) and the ALP was elevated in 65% with a mean of 189u/L (range 47-804u/L). In 33 individuals, PDB had been recorded in the reports of previous X-rays. The rate of referral for specialist care remains low. The prevalence of the condition appears to be falling.

Characteristics and prognosis of telangiectatic osteosarcoma: a population-based study using the Surveillance, Epidemiology and End Results (SEER) database

Background

Telangiectatic osteosarcoma (TOS) is a rare type of osteosarcoma for which limited clinical data is available. Furthermore, the clinical characteristics and prognosis of TOS remain unclear.

Methods

A large population-based cohort analysis was conducted using the Surveillance, Epidemiology and End Results (SEER) registry. The data of TOS and conventional osteosarcoma (COS) patients from 2000 to 2017 were collected. The categorical variables were assessed by Chi-squared tests. Kaplan-Meier curves and log-rank (Mantel-Cox) tests were used to examine the survival outcomes between the groups. Cox proportional hazard models were used for univariate and multivariate analyses of TOS patient survival-related variables.

Results

A total of 141 TOS patients and 2961 COS patients were included in this analysis, and the mean age at diagnosis was 23.5 and 29.4 years, respectively. Compared to COS patients, TOS patients were more likely to be under 20 years old (61.7% vs. 51.7%, P=0.022), and without a second peak of incidence after 60 years of age. The median overall survival (mOS) of TOS patients was not reached compared to a median survival of 84 months for COS patients (hazard ratio 0.75, 95% confidence interval 0.59 to 0.95, P=0.0175). After adjusting these data for age at diagnosis, stage, and surgery at the primary site, no significant differences in mOS were observed between the two groups. In univariate analyses, being under 20 years of age, having localized or regional stage disease, and having undergone surgery were associated with a decreased risk of death. Subsequent multivariate analysis indicated that age at diagnosis, stage, and surgery at the primary site were all independent predictors of prognosis in TOS patients.

Conclusions

Patients with TOS were younger than patients with COS and did not show a second peak after 60 years of age. Age, summary stage at diagnosis, and surgery at the primary site were independent predictors of survival for TOS patients.

Epigenetic analysis of Paget's disease of bone identifies differentially methylated loci that predict disease status

Paget's disease of bone (PDB) is characterized by focal increases in disorganized bone remodeling. This study aims to characterize PDB-associated changes in DNA methylation profiles in patients' blood. Meta-analysis of data from the discovery and cross-validation set, each comprising 116 PDB cases and 130 controls, revealed significant differences in DNA methylation at 14 CpG sites, 4 CpG islands, and 6 gene-body regions. These loci, including two characterized as functional through expression quantitative trait-methylation analysis, were associated with functions related to osteoclast differentiation, mechanical loading, immune function, and viral infection. A multivariate classifier based on discovery samples was found to discriminate PDB cases and controls from the cross-validation with a sensitivity of 0.84, specificity of 0.81, and an area under curve of 92.8%. In conclusion, this study has shown for the first time that epigenetic factors contribute to the pathogenesis of PDB and may offer diagnostic markers for prediction of the disease.

Paget's Disease of Bone: Osteoimmunology and Osteoclast Pathology

PURPOSE OF REVIEW

The purpose of this review is to recognize clinical features of Paget's disease of bone and to describe how the osteoclast, a myeloid-derived cell responsible for bone resorption, contributes to the disease.

RECENT FINDINGS

Recent studies have identified several variants in SQSTM1, OPTN, and other genes that may predispose individuals to Paget's disease of bone; studies of these genes and their protein products have elucidated new roles for these proteins in bone physiology. Understanding the pathologic mechanisms in the Pagetic osteoclast may lead to the identification of future treatment targets for other inflammatory and autoimmune diseases characterized by abnormal bone erosion and/or osteoclast activation.

Incidence of Paget's Disease of Bone in the UK: Evidence of a Continuing Decline

OBJECTIVES

To characterise the incidence of clinically diagnosed Paget's disease of bone in the UK during 1999-2015 and to determine variation in incidence of disease by age, sex, geography and level of deprivation.

METHODS

Incident cases of Paget's disease occurring between 1999-2015 were identified from primary care records. Overall crude incidence and incidence stratified by age and sex was calculated each year from 1999-2015. Direct age- and sex-standardised incidence was also calculated. We used Poisson regression to look at variation in incidence by deprivation and UK region.

RESULTS

3,592 incident cases of Paget's disease were identified between 1999-2015. Incidence increased with age and at all ages was greater in men than women. In women and men, respectively, crude incidence increased from 0.037 and 0.074 per 10 000 population per year among those aged 45-49 years to 3.7 and 6.3 per 10 000 population per year among those 85 years and older. Overall standardised incidence reduced from 0.75/10 000 person-years in 1999-0.20/10 000 person-years in 2015. After adjustment for age and sex, incidence was >30% higher in the most, compared with least deprived quintile of deprivation. There was evidence of geographic variation, with highest incidence in the North West of England, which persisted after adjustment for age, sex, and level of deprivation.

CONCLUSION

The incidence of clinically diagnosed Paget's disease has continued to decrease since 1999. The reason for the decline in incidence remains unknown though the rapidity of change points to an alteration in one or more environmental determinants.

Clinical and radiological outcomes of total hip arthroplasty in patients affected by Paget's disease: a combined registry and single-institution retrospective observational study

BACKGROUND

Total hip arthroplasty (THA) in patients with Paget's disease can be associated with technical difficulties related to deformities and altered mechanical bone properties, and hypervascularity leads to significative intra-operative bleeding. The purpose of this registry and single-institution study was to investigate overall survival and causes of failure of THA in pagetic patients, together with an analysis of the clinical and radiological complications.

MATERIAL AND METHODS

Registry-based survival and complication analysis, type of fixation, intra- and post-operative complications, clinical (pharmacological history, blood transfusions, Harris hip score [HHS]) and radiographic (cup orientation, stem axial alignment, osteolysis around the cup and the stem and heterotopic ossification [HO]) data were reviewed.

RESULTS

In total, 66 patients (27 males and 39 females, mean age at surgery 71.1 years for males and 74.8 years for female) from the registry study presented a 10-year survival of 89.5%. In the institutional study, involving 26 patients (14 males and 12 females, 69 years average) and 29 THAs, hip function improved significantly. Average cup orientation was 40.5°, while varus stem alignment was 13.8%. In total, 52% of hips had heterotopic ossifications. Peri-acetabular osteolysis was in 13.8% of implants and in 45% of hips was found around the stem. Allogenic and autologous blood transfusion rate were 68.2% and 31.8%, respectively, with an average transfusion of 2 units of blood (range 1-6 units). HHS improved by an average of 34 points, with excellent result in 64.3% of patients. Two implants failed, one due to traumatic ceramic head fracture 64 months after surgery, and one due to mobilization of the cup on the second post-operative day.

CONCLUSION

THA surgery in Paget's patients is a safe procedure, and implant survival is only partly affected by bone remodelling and choice of fixation. The post-operative functional outcome is largely similar to that of other patients. Bleeding-related complications are the main complications; a careful pharmacological strategy should be recommended to decrease the risk of transfusions and of HO development.

LEVEL OF EVIDENCE

Level III.

Survey of MRI Usefulness for the Clinical Assessment of Bone Microstructure

Bone microarchitecture has been shown to provide useful information regarding the evaluation of skeleton quality with an added value to areal bone mineral density, which can be used for the diagnosis of several bone diseases. Bone mineral density estimated from dual-energy X-ray absorptiometry (DXA) has shown to be a limited tool to identify patients' risk stratification and therapy delivery. Magnetic resonance imaging (MRI) has been proposed as another technique to assess bone quality and fracture risk by evaluating the bone structure and microarchitecture. To date, MRI is the only completely non-invasive and non-ionizing imaging modality that can assess both cortical and trabecular bone in vivo. In this review article, we reported a survey regarding the clinically relevant information MRI could provide for the assessment of the inner trabecular morphology of different bone segments. The last section will be devoted to the upcoming MRI applications (MR spectroscopy and chemical shift encoding MRI, solid state MRI and quantitative susceptibility mapping), which could provide additional biomarkers for the assessment of bone microarchitecture.

Comprehensive Analysis of Aerobic Exercise-Related Genes Identifies CDCA4 That Promotes the Progression of Osteosarcoma

Background

Exercise has a positive impact on patients with osteosarcoma, improving function, reducing disability, maintaining independence and quality of life. Exercise may also directly affect the effectiveness of cancer treatment. Cell division cycle-associated protein 4 (CDCA4) is reported to function importantly during numerous human cancers development. Nevertheless, the details toward CDCA4 function are still to be investigated.

Methods

This study comprehensively analyzed the GSE74194 database and obtained aerobic exercise-related genes. Protein-protein interaction network (PPI) and Gene Ontology (GO) analysis were performed on the differentially expressed genes (DEGs). Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and tumor genome atlas (TCGA) data mining were applied to measure aerobic exercise-related gene CDCA4 level in osteosarcoma tissue. We conducted lots of functional experiments to uncover CDCA4 function and its corresponding mechanism in osteosarcoma.

Results

We screened a total of 547 DEGs related to aerobic exercise, of which 373 were up-regulated and 174 were down-regulated. PPI analysis revealed 90 genes that might play key roles. GO analysis showed that aerobic exercise-related DEGs were significantly enriched during the mitotic cell cycle, cell division, mitotic nuclear division and sister chromatid segregation, nuclear division, microtubule cytoskeleton organization involved protein, microtubule-based process, spindle organization, G2/M transition of mitotic cell cycle. Our results indicated that CDCA4 was increased in osteosarcoma tissues and cell lines, and its level had association with high mortality of osteosarcoma patients. Further studies revealed that absence of CDCA4 largely hindered osteosarcoma cancer cell proliferation, invasion, and migration.

Conclusion

Comprehensive bioinformatics analysis improves our understanding of the underlying molecular mechanisms of aerobic exercise on osteosarcoma. This provides evidence for the effect of aerobic exercise on CDCA4 expression. Our data suggested that CDCA4 could facilitate osteosarcoma development, and gave a hint that CDCA4 was a candidate target in the treatment of osteosarcoma, aerobic exercise might help the treatment and prognosis of patients with osteosarcoma.

Pattern of SQSTM1 Gene Variants in a Hungarian Cohort of Paget's Disease of Bone

Paget's disease of bone (PDB) is characterized by focal or multifocal increase in bone turnover. One of the most well-established candidate genes for susceptibility to PDB is Sequestosome 1 (SQSTM1). Mutations in SQSTM1 have been documented among Western-European, British and American patients with PDB. However, there is no information on SQSTM1 mutation status in PDB patients from the Central- and Eastern-European regions. In this study, we conducted a mutation screening for SQSTM1 gene variants in 82 PDB patients and 100 control participants in Hungary. Mutations of SQSTM1 were detected in 18 PDB patients (21.95%); associations between genotype and clinical characteristics were also analyzed. Altogether, six different exonic alterations, including two types of UTR variants in the SQSTM1 gene, were observed in our PDB patients. Similarly, to previous genetic studies on Paget's disease, our most commonly detected variant was the c.1175C > T (p.Pro392Leu) in nine cases (four in monostotic and five in polyostotic form). We have surveyed the germline SQSTM1 variant distribution among Hungarian patients with PDB. We also highlighted that the pattern of the analyzed disease-associated pathophysiological parameters could partially discriminate PDB patients with normal or mutant SQSTM1 genotype. However, our findings also underline and strengthen that not solely SQSTM1 stands in the background of the complex PDB etiology.

Increased Prevalence of Nephrolithiasis and Hyperoxaluria in Paget Disease of Bone

CONTEXT

Nephrolithiasis (NL) and primary hyperparathyroidism (HPTH) are metabolic complications of Paget disease of bone (PDB), but recent data regarding their prevalence in PDB patients are lacking.

OBJECTIVES

Study 1: To compare the prevalence of primary HPTH and NL in 708 patients with PDB and in 1803 controls. Study 2: To evaluate the prevalence of NL-metabolic risk factors in 97 patients with PDB and NL, 219 PDB patients without NL, 364 NL patients without PDB, and 219 controls, all of them without HPTH.

DESIGN

Cross-sectional multicentric study.

SETTING

Italian referral centers for metabolic bone disorders.

PARTICIPANTS

Patients with PDB from the Associazione Italiana malati di osteodistrofia di Paget registry. Participants in the Olivetti Heart and the Siena Osteoporosis studies.

MAIN OUTCOME MEASURES

HPTH; NL; NL-metabolic risk factors.

RESULTS

Patients with PDB showed higher prevalence of primary HPTH and NL compared with controls (P < 0.01). The NL recurrence occurs more frequently in patients with polyostotic PDB. About one-half of patients with PDB but without NL showed 1 or more NL-related metabolic risk factors. The hyperoxaluria (HyperOx) prevalence was higher in patients with PDB and NL compared with patients with NL but without PDB and in patients with PDB without NL compared with controls (P = 0.01). Patients with PDB and HyperOx showed a longer lapse of time from the last aminobisphosphonate treatment.

CONCLUSIONS

NL and HPTH are frequent metabolic complication of PDB. The NL occurrence should be evaluated in patients with PDB, particularly in those with polyostotic disease and/or after aminobisphosphonate treatment to apply an adequate prevention strategy.

The Genetic Architecture of High Bone Mass

The phenotypic trait of high bone mass (HBM) is an excellent example of the nexus between common and rare disease genetics. HBM may arise from carriage of many 'high bone mineral density [BMD]'-associated alleles, and certainly the genetic architecture of individuals with HBM is enriched with high BMD variants identified through genome-wide association studies of BMD. HBM may also arise as a monogenic skeletal disorder, due to abnormalities in bone formation, bone resorption, and/or bone turnover. Individuals with monogenic disorders of HBM usually, though not invariably, have other skeletal abnormalities (such as mandible enlargement) and thus are best regarded as having a skeletal dysplasia rather than just isolated high BMD. A binary etiological division of HBM into polygenic vs. monogenic, however, would be excessively simplistic: the phenotype of individuals carrying rare variants of large effect can still be modified by their common variant polygenic background, and by the environment. HBM disorders-whether predominantly polygenic or monogenic in origin-are not only interesting clinically and genetically: they provide insights into bone processes that can be exploited therapeutically, with benefits both for individuals with these rare bone disorders and importantly for the many people affected by the commonest bone disease worldwide-i.e., osteoporosis. In this review we detail the genetic architecture of HBM; we provide a conceptual framework for considering HBM in the clinical context; and we discuss monogenic and polygenic causes of HBM with particular emphasis on anabolic causes of HBM.

Bisphosphonates in the management of Paget's disease

The first clinical use of bisphosphonates was in Paget's disease of bone (PDB) when disodium etidronate was found to be effective at suppressing metabolic activity of the disease. Subsequently, PDB became a testing ground for many bisphosphonates using changes in alkaline phosphatase (ALP) as the primary outcome measure in clinical trials. Bisphosphonates are now considered to be the treatment of choice for PDB since they are highly effective at suppressing the elevations in bone turnover that are characteristic of the disease. Short term studies have shown that treatment with alendronate and risedronate can promote formation of lamellar bone in affected sites and improve x-ray appearances in some patients. Bisphosphonates have also been shown to improve bone pain in PDB and within the bisphosphonates, zoledronic acid (ZA) is most likely to give a favourable pain response. Many patients with PDB do not have pain however, even when there is increased metabolic activity and more research is needed to find out why this is the case. The effects of bisphosphonates on complications of PDB such as deformity, pathological fractures and deafness have not been adequately studied since most clinical trials have been short term and have not collected information on these important outcomes. The PRISM and PRISM-EZ studies investigated the long-term effects of bisphosphonates in patients with established PDB using a treat-to-target approach and showed that intensive bisphosphonate therapy aimed at normalising ALP was no more effective than symptom directed treatment with bisphosphonates at preventing complications of PDB. The Zoledronate in the Prevention of Paget's Disease (ZiPP) trial, which is currently in progress, seeks to determine whether early intervention with this potent bisphosphonate might be effective in preventing disease progression. Should the ZiPP study yield positive results, genetic testing coupled to prophylactic bisphosphonate therapy might represent a new indication for these highly effective inhibitors of bone resorption in future years.

Mutation of PFN1 Gene in an Early Onset, Polyostotic Paget-like Disease

CONTEXT

Paget disease of bone (PDB) is a metabolic bone disease whose genetic cause remains unknown in up to 50% of familial patients.

OBJECTIVE

Our aim was to investigate the underlying genetic defect in a large pedigree with a severe, early onset, autosomal dominant form of PDB across 3 generations.

METHODS

Whole exome sequencing was performed in affected and unaffected family members, and then mutation screening was replicated in a sample of PDB patients with early-onset, polyostotic PDB.

RESULTS

We identified a frameshift D107Rfs*3 mutation in PFN1 (encoding for profilin 1, a highly conserved regulator of actin-polymerization and cell motility) causing the truncation of the C-terminal part of the protein. The mutation was also detected in a 17-year-old asymptomatic family member who upon biochemical and radiological analyses was indeed found to be affected. Sequencing of the entire PFN1 coding region in unrelated PDB patients identified the same mutation in 1 patient. All mutation carriers had a reduced response to bisphosphonates, requiring multiple zoledronate infusions to control bone pain and achieve biochemical remission over a long term. In vitro osteoclastogenesis in peripheral blood mononuclear cells (PBMCs) from mutation carriers showed a higher number of osteoclasts with PDB-like features. A similar phenotype was observed upon PFN1 silencing in murine bone marrow-derived monocytes, suggesting that the frameshift PFN1 mutation confers a loss of function in profilin 1 activity that induces PDB-like features in the osteoclasts, likely due to enhanced cell motility and actin ring formation.

CONCLUSIONS

Our findings indicate that PFN1 mutation causes an early onset, polyostotic PDB-like disorder.

Molecular modelling and dynamic simulations of sequestosome 1 (SQSTM1) missense mutations linked to Paget disease of bone

The Paget disease (PDB; OMIM is 167250) is a chronic bone disease caused by pathogenic mutations in Sequestome1/p62 (SQSTM1) gene. This study has aimed to interpret the relationship of PDB linked SQSTM1 mutations with protein structure and its molecular dynamic features. The disease causative missense mutations were initially collected, and then analyzed for their, exonic and domain distribution, impact on secondary and tertiary structures, and their ability on protein-ligand interactions, using a combination of systems biology approaches. Our results show that most PDB linked SQSTM1 missense mutations affect amino acid residues clustered within or near the UBA domain (aa 389-434), which participates in the ubiquitination of substrates. We also report that the majority mutations occurred in α-helices over β-strands but their effects on the secondary structure were mostly neutral. Global tertiary structure deviations were minimal; however, at amino acid residue level minor structural changes were evident. The molecular dynamics simulation analysis showed that both PB1 and UBA domains were under constant structural fluctuations resulting in closed form conformation of SQSMT1 protein structure, when it is bound to PRKCI ligand. We also found salt bridge conformation changes in the UBA domain of SQSTM1 mutants when they bound to the PRKCI interactor protein. This finding suggests the possibility that mutations in SQSTM1 could impair its ability to ubiquitinate the substrates, eventually affecting autophagy and apoptosis, especially in mature osteoclasts. This study presents the additional insight into structure and function relationship between SQSTM1 mutations and PDB pathogenesis. Communicated by Ramaswamy H. Sarma.

Oleuropein and its peracetylated derivative negatively regulate osteoclastogenesis by controlling the expression of genes involved in osteoclast differentiation and function

OL and Per-OL impair transcriptional gene circuits able to support osteoclastogenesis from human blood monocytes.