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Normocalcemic hyperparathyroidism (NHPT) is variably defined, and information regarding complications and natural history are scarce. We aimed to describe the phenotype of NHPT in relation to hypercalcemic hyperparathyroidism (PHPT) and controls, to determine risk of progression, and to develop a predictive model for progression to PHPT. This is a retrospective chart review of 232 patients at a tertiary medical center, comparing 75 controls, 73 patients with NHPT, and 84 with PHPT. NHPT was intermediate in biochemical profile between controls and PHPT with respect to cCa, iPTH, intraindividual coefficient of variant of cCa, phosphorus, and 25(OH)D. NHPT patients had an increased adjusted risk of urolithiasis (OR 5.34, 95%CI, 2.41-12.71, P < .001) and fragility fractures (OR 4.53, 95%CI, 1.63-14.84, P = .006) versus controls, after adjustment for age, sex, and BMI. Fewer NHPT compared with PHPTH patients achieved cure with parathyroidectomy (P = .001). NHPT more often had nonlocalizing imaging or polyglandular disease (P = .005). Parathyroidectomy improved biochemical but not BMD parameters in NHPT. Over a median follow-up of 4.23 (IQR 1.76-5.31) years, NHPT patients managed expectantly experienced no change in iPTH, and progression to PHPT occurred in 9%. An XGBoost model combining 6 factors for progression (mean index 2 iPTH, mean index 2 cCa, 24-h urinary calcium, age, 25(OH)D, and presence of urolithiasis) had an area under the curve 1.00 (95%CI, 1.00-1.00, P < .001) for predicting combined progression. NHPT is a mild variant of PHPT at intermediate risk of urolithiasis and fragility fractures. Cure was less often achieved with parathyroidectomy, which did not improve BMD parameters. Progression was infrequent with conservative management. Because only a minority progressed to PHPT, in addition to lower surgical success rates, we suggest conservative management for the majority of NHPT unless risk factors for progression are identified.

Raloxifene increases lumbar spine bone mineral density (BMD) and lowers vertebral fracture risk in patients with osteoporosis. However, few prospective clinical trials have studied its efficacy in postmenopausal women with osteopenia. This study investigated the efficacy of raloxifene in postmenopausal women with osteopenia. An investigator-initiated, randomized, open-label, prospective, single-center trial was conducted in 112 postmenopausal women with osteopenia. Osteopenia was defined based on the lowest BMD T-score in the lumbar spine, femoral neck, or total hip (-2.5 < lowest T-score < -1.0). Participants were randomly assigned to receive raloxifene 60 mg/day plus cholecalciferol 800 IU/day (RalD) or cholecalciferol 800 IU/day (VitD) for 48 wk. At baseline, mean age (63.1 ± 6.8 yr) did not differ between the two groups. However, in the RalD group, mean body mass index (BMI) and baseline T-score were lower, while 25-hydroxyvitamin D level was higher. At 48 wk, the RalD group showed a greater increase in lumbar spine BMD (RalD vs. VitD; 2.6% vs. -0.6%, P =.005) and attenuated the total hip BMD loss (-0.3% vs. -2.9%, P = .003). The effect of raloxifene on the lumbar spine remained significant after adjustment for age, BMI, baseline BMD T-score, and other covariates (adjusted β: +3.05 vs. VitD, P =.015). In subgroup analysis, the difference in lumbar spine BMD between the RalD and VitD groups was robust in those with severe osteopenia group (lowest T-score ≤ -2.0). Raloxifene plus cholecalciferol significantly improved lumbar spine BMD and attenuated total hip BMD loss compared with cholecalciferol alone, with a more robust effect in severe osteopenia. Clinical trial registration: The trial was registered with ClinicalTrials.gov (NCT05386784).

Langerhans cell histiocytosis (LCH) is a rare disease with limited treatment options. We present a case involving a 57-year-old woman afflicted with an isolated LCH bone osteolytic lesion. A single bisphosphonate infusion significantly alleviated pain, and follow-up scans via CT, PET-CT, and MRI revealed a substantial recalcification of the lesion. Conducting an extensive literature review, we identified 46 cases documenting the efficacy of bisphosphonates in the context of LCH. These findings have raised interest in bisphosphonate infusion as a simple therapeutic alternative in similar situations, with benefits in terms of bone recalcification and pain control for individuals with LCH.

Genome wide association study (GWAS)-implicated bone mineral density (BMD) signals have been shown to localize in cis-regulatory regions of distal effector genes using 3D genomic methods. Detailed characterization of such genes can reveal novel causal genes for BMD determination. Here, we elected to characterize the "DNM3" locus on chr1q24, where the long non-coding RNA DNM3OS and the embedded microRNA MIR199A2 (miR-199a-5p) are implicated as effector genes contacted by the region harboring variation in linkage disequilibrium with BMD-associated sentinel single nucleotide polymorphism, rs12041600. During osteoblast differentiation of human mesenchymal stem/progenitor cells (hMSC), miR-199a-5p expression was temporally decreased and correlated with the induction of osteoblastic transcription factors RUNX2 and Osterix. Functional relevance of miR-199a-5p downregulation in osteoblastogenesis was investigated by introducing miR-199a-5p mimic into hMSC. Cells overexpressing miR-199a-5p depicted a cobblestone-like morphological change and failed to produce BMP2-dependent extracellular matrix mineralization. Mechanistically, a miR-199a-5p mimic modified hMSC propagated normal SMAD1/5/9 signaling and expressed osteoblastic transcription factors RUNX2 and Osterix but depicted pronounced upregulation of SOX9 and enhanced expression of essential chondrogenic genes ACAN, COMP, and COL10A1. Mineralization defects, morphological changes, and enhanced chondrogenic gene expression associated with miR-199a-5p mimic over-expression were restored with miR-199a-5p inhibitor suggesting specificity of miR-199a-5p in chondrogenic fate specification. The expression of both the DNM3OS and miR-199a-5p temporally increased and correlated with hMSC chondrogenic differentiation. Although miR-199a-5p overexpression failed to further enhance chondrogenesis, blocking miR-199a-5p activity significantly reduced chondrogenic pellet size, extracellular matrix deposition, and chondrogenic gene expression. Taken together, our results indicate that oscillating miR-199a-5p levels dictate hMSC osteoblast or chondrocyte terminal fate. Our study highlights a functional role of miR-199a-5p as a BMD effector gene at the DNM3 BMD GWAS locus, where patients with cis-regulatory genetic variation which increases miR-199a-5p expression could lead to reduced osteoblast activity.

Triple-negative breast cancer (TNBC) is thought to be an estradiol-independent, hormone therapy-resistant cancer because of lack of estrogen receptor alpha 66 (ERα66). We identified a membrane-bound splice variant, ERα36, in TNBC cells that responds to estrogen (E₂) and may contribute to bone osteolysis. We demonstrated that the MDA-MB-231 TNBC cell line, which expresses ERα36 similarly to MCF7 cells, is responsive to E₂, forming osteolytic tumors in vivo. MDA-MB-231 cells activate osteoclasts in a paracrine manner. Conditioned media (CM) from MDA-MB-231 cells treated with bovine serum albumin-bound E₂ (E₂-BSA) increased activation of human osteoclast precursor cells; this was blocked by addition of anti-ERα36 antibody to the MDA-MB-231 cultures. Osteoclast activation and bone resorption genes were elevated in RAW 264.7 murine macrophages following treatment with E₂-BSA-stimulated MDA-MB-231 CM. E₂ and E₂-BSA increased phospholipase C (PLC) and protein kinase C (PKC) activity in MDA-MB-231 cells. To examine the role of ERα36 signaling in bone osteolysis in TNBC, we used our bone-cancer interface mouse model in female athymic homozygous Foxn1^nu mice. Mice with MDA-MB-231 tumors and treated with tamoxifen (TAM), E₂, or TAM/E₂ exhibited increased osteolysis, cortical bone breakdown, pathologic fracture, and tumor volume; the combined E₂/TAM group also had reduced bone volume. These results suggest that E₂ increased osteolytic lesions in TNBC through a membrane-mediated PLC/PKC pathway involving ERα36, which was enhanced by TAM, demonstrating the role of ERα36 and its membrane-associated signaling pathway in bone tumors. This work suggests that ERα36 may be a potential therapeutic target in patients with TNBC.

MicroRNAs are involved in post-transcriptional regulation of gene expression. Due to their regulatory role, microRNAs are differently expressed during specific conditions in healthy and diseased individuals, so microRNAs circulating in the blood could be used as diagnostic and prognostic biomarkers for various diseases and conditions. We want to investigate the variability of circulating microRNAs and bone turnover markers in weekly time intervals in older women. In a single-site longitudinal study, a panel of 19 bone-related miRNAs was measured using the osteomiR RT-qPCR assay in serum samples of 35 postmenopausal women divided into 3 groups: healthy controls (n = 12), low BMD (n = 14), and vertebral fractures (n = 9). Blood samples for measurement of CTX, PINP, OC, and bone ALP were collected once per week for 8 weeks at 9:00 AM after overnight fasting. Serum samples from all participants were analyzed for 19 microRNA bone biomarkers and 4 bone turnover markers over 8 weeks. We analyzed the data using a mixed model analysis of variance and found no significant changes between week-by-week time points in any of the groups. To estimate intraindividual variability between weekly time points, we have calculated the median coefficient of variation (CV). This was between 28.4% and 80.2% for microRNA, with an assay CV of 21.3%. It was between 8.5% and 15.6% for bone turnover markers, with an assay CV of 3.5% to 6.5%. The intraindividual variability was similar between groups. Circulating microRNAs measured in serum had a higher weekly intraindividual variability than bone turnover markers due in part to a higher assay CV.

Osteoporosis and associated fractures are an increasingly prevalent concern with an ageing population. This study reports testing of IBEX Bone Health (IBEX BH) software, applied following acquisition of forearm radiographs. IBEX Bone Health analyses the radiograph to measure areal bone mineral density (aBMD) at the examination site. A non-randomized cross-sectional study design was performed involving 261 (254 after exclusions) participants (112/142 m/f; mean age 70.8 years (SD+/-9.0); 53 with osteoporosis). They underwent posterior-anterior distal forearm radiographs; dual X-ray absorptiometry (DXA) of the wrists, hips, and lumbar spine; and questionnaires exploring clinical risk factors. IBEX Bone Health automatically identifies regions of interest (ROI) at the ultra-distal (UD) and distal third (TD) regions of the radius. Analysis investigated area under the receiver operating characteristics curve performance of IBEX BH for prediction of (i) osteoporosis (based on clinical reporting of the hip and spine DXA) and (ii) treatment recommendations by Fracture Risk Assessment Tool (FRAX) inclusive of neck of femur (NoF) areal bone mineral density (aBMD) results following National Osteoporosis Guideline Group (NOGG) guidelines. Area under the receiver operating characteristics curve for osteoporosis prediction at the UD and TD ROIs were 0.86 (99% confidence interval (CI) [0.80, 0.91]) and 0.81 (99% CI [0.75, 0.88]), respectively. Area under the receiver operating characteristics curve for treatment recommendation using FRAX inclusive of NoF aBMD at the UD and TD ROIs were 0.95 (99% CI [0.91, 1.00]) and 0.97 (99% CI [0.93,1.00]), respectively. With a matched sensitivity to FRAX (without NoF aBMD) 0.93 (99% CI [0.78, 0.99]), IBEX BH predicted at the UD and TD ROIs recommended treatment outcomes by NOGG guidelines using FRAX (with NoF aBMD) with specificity 0.89 (99% CI 0.83, 0.94]) and 0.93 (99% CI [0.87, 0.97]), respectively. This is compared with 0.60 (99% CI [0.51, 0.69]) for FRAX (without NoF aBMD). Results demonstrate the potential clinical utility of IBEX BH as an opportunistic screening tool.

Nonunion resulting from early bone resorption is common after bone transplantation surgery. In these patients, instability or osteoporosis causes hyperactive catabolism relative to anabolism, leading to graft resorption instead of fusion. Systemic zoledronate administration inhibits osteoclastogenesis and is widely used to prevent osteoporosis; however, evidence on local zoledronate application is controversial due to osteoblast cytotoxicity, uncontrolled dosing regimens, and local release methods. We investigated the effects of zolendronate on osteoclastogenesis and osteogenesis and explored the corresponding signaling pathways. In vitro cytotoxicity and differentiation of MC3T3E1 cells, rat bone marrow stromal cells (BMSCs) and preosteoclasts (RAW264.7 cells) were evaluated with different zolendronate concentrations. In vivo bone regeneration ability was tested by transplanting different concentrations of zolendronate with β-tricalcium phosphate (TCP) bone substitute into rat femoral critical-sized bone defects. In vitro, zolendronate concentrations below 2.5 × 10^-7 M did not compromise viability in the three cell lines and did not promote osteogenic differentiation in MC3T3E1 cells and BMSCs. In RAW264.7 cells, zoledronate inhibited extracellular regulated protein kinases and c-Jun n-terminal kinase signaling, downregulating c-Fos and NFATc1 expression, with reduced expression of fusion-related dendritic cell‑specific transmembrane protein and osteoclast-specific Ctsk and tartrate-resistant acid phosphatase (. In vivo, histological staining revealed increased osteoid formation and neovascularization and reduced fibrotic tissue with 500 μM and 2000 μM zolendronate. More osteoclasts were found in the normal saline group after 6 weeks, and sequential osteoclast formation occurred after zoledronate treatment, indicating inhibition of bone resorption during early callus formation without inhibition of late-stage bone remodeling. In vivo, soaking β-TCP artificial bone with 500 μM or 2000 μM zoledronate is a promising approach for bone regeneration, with potential applications in bone transplantation.

Osteitis of the sternocostoclavicular (SCC) region, referred to as sternocostoclavicular hyperostosis (SCCH), is the clinical expression of chronic non-bacterial osteitis (CNO) in adults with this rare chronic auto-inflammatory disorder of the axial skeleton. The diagnosis is based on distinctive computerized tomography (CT) features of sclerosis and hyperostosis of the SCC region, and local increases in osteoid formation visualized by high radiopharmacon uptake on skeletal scintigraphy but clear radiologic diagnostic criteria are lacking. In a cross-sectional study, CT scans and whole-body skeletal scintigraphy images obtained in 169 patients seen at the Center for Bone Quality of the Leiden University Medical Center between 2008 and 2018 with a suspected diagnosis of CNO of the SCC region were re-evaluated by 2 skeletal radiologists and 2 nuclear physicians. The diagnosis was confirmed in 118 (70%) predominantly female patients (n = 103, 89.2%); median age at first symptoms 45 years (range 20-73). The diagnosis was excluded in the remaining 51 "non-CNO" patients. Increased radiopharmacon uptake at the SCC region was observed in 82% CNO patients, with the manubrium sterni having the highest predictive ability to discriminate on both imaging modalities. The prevalence of sclerosis of the clavicles, manubrium and first ribs was significantly higher in CNO patients (P < 0.001). Hyperostosis was not observed in non-CNO patients. 46 CNO versus only 2 non-CNO patients had costoclavicular ligament calcification. Our findings identify CT scan features of sclerosis and hyperostosis of manubrium sterni, medial end of clavicles and first ribs, and calcification of costoclavicular ligaments, associated with increased tracer uptake on skeletal scintigraphy at the SCC region, specifically manubrium sterni, as well-defined imaging diagnostic criteria for adult CNO. Pitfalls encountered in the diagnosis of CNO are highlighted. These defined imaging diagnostic criteria for adult CNO should facilitate the diagnosis of this rare auto-inflammatory bone disease across the spectrum of its early to late stages.

Craniofacial osteoclasts are essential for site-specific processes such as alveolar bone resorption, tooth eruption, and orthodontic tooth movement. Much of the current understanding of osteoclast development and function comes from studies using long bone-derived cells. Minimal investigation has been done to explore skeletal site differences. The overall goal of this study was to determine if mandibular- and femoral-derived osteoclasts represent distinct populations. To test this hypothesis, bone marrow cells were initially analyzed from the mandible and femur of 2-month-old mice. It was shown that mandibular-derived osteoclasts have enhanced size (mm²) compared with femoral-derived osteoclasts. Since bone marrow macrophages are a heterogenous population, we additionally selected for monocytes and demonstrated that mandibular-derived monocytes also form osteoclasts with increased size compared with femoral-derived monocytes. Osteoclast precursor populations from both skeletal sites were analyzed by flow cytometry. A newly described Ly6C^High+ population as well as the Ly6C^int population was increased in the mandibular-derived cells. The difference in differentiation potential between monocyte cultures suggests that the increase in the Ly6C^High+ population may explain the enhanced differentiation potential in mandibular-derived cells. Monocyte genes such as Pu.1, C/ebp-a, and Prdm1 are increased in expression in mandibular-derived monocytes compared with femoral-derived monocytes. As expected with enhanced differentiation, osteoclast genes including Nfatc1, Dc-stamp, Ctsk, and Rank are upregulated in mandibular-derived osteoclast precursors. Future studies will determine how changes in the environment of the mandible lead to changes in percentages of osteoclast progenitors and their differentiation potential.