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Dual-energy X-ray absorptiometry (DXA) is underutilized to measure bone mineral density (BMD) and evaluate fracture risk. We present an automated tool to identify fractures, predict BMD, and evaluate fracture risk using plain radiographs. The tool performance is evaluated on 5164 and 18175 patients with pelvis/lumbar spine radiographs and Hologic DXA. The model is well calibrated with minimal bias in the hip (slope = 0.982, calibration-in-the-large = −0.003) and the lumbar spine BMD (slope = 0.978, calibration-in-the-large = 0.003). The area under the precision-recall curve and accuracy are 0.89 and 91.7% for hip osteoporosis, 0.89 and 86.2% for spine osteoporosis, 0.83 and 95.0% for high 10-year major fracture risk, and 0.96 and 90.0% for high hip fracture risk. The tool classifies 5206 (84.8%) patients with 95% positive or negative predictive value for osteoporosis, compared to 3008 DXA conducted at the same study period. This automated tool may help identify high-risk patients for osteoporosis. Dual-energy X-ray absorptiometry and the Fracture Risk Assessment Tool are recommended tools for osteoporotic fracture risk evaluation, but are underutilized. Here, the authors present an opportunistic tool to identify fractures, predict bone mineral density and evaluate fracture risk using plain pelvis and lumbar spine radiographs.

To explore the pathologies of Kashin-Beck disease (KBD) and KBD accompanied with dental fluorosis (DF), we conducted a comparative analysis of gene expression profiles. 12 subjects were recruited, including 4 KBD patients, 4 patients with KBD and DF and 4 healthy subjects. Genome-wide expression profiles from their peripheral blood mononuclear cells were evaluated by customized oligonucleotide microarray. R programming software was used for the microarray data analysis followed by functional enrichment analysis through KOBAS. Several potential biomarkers were identified, and quantitative real-time reverse transcription–polymerase chain reaction (qRT-PCR) was used for their validation. In this study, 28 genes and 8 genes were found to be up- and down-regulated respectively in KBD patients compared with health subjects. In patients with KBD and DF, we obtained 10 up-regulated and 3 down-regulated genes compared with health controls. Strikingly, no differential expression gene (DEG) was identified between the two groups of patients. A total of 10 overlaps (DUSP2, KLRF1, SRP19, KLRC3, CD69, SIK1, ITGA4, ID3, HSPA1A, GPR18) were obtained between DEGs of patients with KBD and patients with KBD and DF. They play important roles in metabolism, differentiation, apoptosis and bone-development. The relative abundance of 8 DEGs, i.e. FCRL6, KLRC3, CXCR4, CD93, CLK1, GPR18, SRP19 and KLRF1, were further confirmed by qRT-PCR analysis.

B-cell development is dependent on the interactions between B-ceU precursors and bone marrow stromal cells, but the role of osteoclasts （OCLs） in this process remains unknown. B lymphocytopenia is a characteristic of osteopetrosis, suggesting a modulation of B lymphopoiesis by OCL activity. To address this question, we first rescued OCL function in osteopetrotic oc/oc mice by dendritic cell transfer, leading to a restoration of both bone phenotype and B-cell development. To further explore the link between OCL activity and B lymphopoiesis, we induced osteopetrosis in normal mice by injections of zoledronic acid （ZA）, an inhibitor of bone resorption. B-cell number decreased specifically in the bone marrow of ZA-treated mice. ZA did not directly affect B-cell differentiation, proliferation and apoptosis, but induced a decrease in the expression of CXCL12 and IL-7 by stromal cells, associated with reduced osteoblastic engagement. Equivalent low osteoblastic engagement in oc/oc mice confirmed that it resulted from the reduced OCL activity rather than from a direct effect of ZA on osteoblasts. These dramatic alterations of the bone mieroenvironment were disadvantageous for B lymphopoiesis, leading to retention of B-cell progenitors outside of their bone marrow niches in the ZA-induced osteopetrotic model. Altogether, our data revealed that OCLs modulate B-cell development in the bone marrow by controlling the bone microenvironment and the fate of osteoblasts. They provide novel basis for the regulation of the retention of B cells in their niche by OCL activity.

A new study shows in mice that tumor necrosis factor (TNF) superfamily member 11 (TNFSF11, also known as RANKL), which stimulates osteoclasts to remove bone, binds to the G-protein-coupled receptor LGR4 to prevent excessive bone removal. In mouse models of osteoporosis, a recombinant LGR4 ectodomain reduces bone loss.

Osteoporosis can be secondary to an underlying metabolic, nutritional, pharmacologic or disease-related cause; in such cases the triggering factor should be identified and treated. Approaches to the identification and management of patients with secondary osteoporosis are outlined in this Review, alongside mechanistic insights into the bone pathology. Osteoporosis, through its association with fragility fracture, is a major public health problem, costing an estimated $34.8 billion worldwide per annum. With projected demographic changes, the burden looks set to grow. Therefore, the prevention of osteoporosis, as well as its identification and treatment once established, are becoming increasingly important. Osteoporosis is secondary when a drug, disease or deficiency is the underlying cause. Glucocorticoids, hypogonadism, alcohol abuse and malnutrition are among the most frequently recognized causes of secondary osteoporosis but the list of implicated diseases and drugs is growing and some of the more recently recognized associations, such as those with haematological conditions and acid-suppressing medications, are less well publicized. In some cases, advancement in treatment of the primary disease has led to people living long enough to develop secondary osteoporosis; for example, successful treatment for breast and prostate malignancies by hormonal manipulation, improved survival in HIV with the advent of anti-retroviral therapies, and improved treatment for cystic fibrosis. This Review emphasizes the importance of secondary osteoporosis, discusses familiar and less well-known causes and what is known of their mechanisms, provides guidance as to the pragmatic identification of secondary osteoporosis and summarizes treatment options, where available. Key Points Osteoporosis and associated fragility fractures are major public health problems, but once fractures develop, it is already too late; thus, prevention is a priority A growing number of diseases, deficiencies and drugs are recognised as causing secondary osteoporosis, and should be suspected as causes in particular among men and pre-menopausal women presenting with osteoporosis In most cases, the general principle of treatment of secondary osteoporosis is to treat the underlying disease or deficiency, or to remove the relevant drug Mechanisms of secondary osteoporosis vary and include low bone mass, increasing falls, and reduced bone quality—treatment strategies might need to be adapted for different patients

Autosomal dominant osteopetrosis type II (ADO II) is a rare, heritable bone disorder characterized by a high bone mass and insufficient osteoclast activity. Mutations in the CLCN7 gene have been reported to cause ADO II. To gain novel insights into the pathways dysregulated in ADOII osteoclasts, we identified changes in gene expression in osteoclasts from patients with a heterozygous mutation of CLCN7. To do this, we carried out a transcriptomic study comparing gene expression in the osteoclasts of patients with ADO II and healthy donors. Our data show that, according to our selection criteria, 182 genes were differentially expressed in osteoclasts from patients and controls. From the 18 displaying the highest change in microarray, we confirmed differential expression for seven by qPCR. Although two of them have previously been found to be expressed in osteoclasts (ITGB5 and SERPINE2), the other five (CES1 (carboxyl esterase 1), UCHL1 (ubiquitin carboxy-terminal esterase L1, also known as ubiquitin thiolesterase), WARS (tryptophanyl-tRNA synthetase), GBP4 (guanylate-binding protein 4), and PRF1) are not yet known to have a role in this cell type. At the protein level, we confirmed elevated expression of ITGB5 and reduced expression of WARS, PRF1, and SERPINE2. Transfection of ClC-7 harboring the G215R mutation into osteoclasts resulted in an increased ITGB5 and reduced PRF1 expression of borderline significance. Finally, we observed that the ADO II patients presented a normal or increased serum level of bone formation markers, demonstrating a coupling between dysfunctional osteoclasts and osteoblasts. Sphingosine kinase 1 mRNA was expressed at the same level in ADO II and control osteoclasts. In conclusion, these data suggest that in addition to an acidification dysfunction caused by the CLCN7 mutation, a change in ITGB5, PRF1, WARS, and SERPINE2 expression could be part of the osteoclastic phenotype of ADO II.