Pathophysiology of osteoporosis: new mechanistic insights

Bone mechanical loading reduces heart rate and increases heart rate variability in mice

Cardiovascular disease and osteoporosis are clinically associated. Bone adapts to mechanical forces by altering its overall structure and mass. In response to mechanical strain bone cells release signaling molecules and activate the nervous system. Bone also exhibits endocrine functions that modulate a number of tissues including the heart. We hypothesized that bone mechanical loading acutely alters cardiac function via neural and/or endocrine mechanisms. To test this hypothesis, we performed in vivo tibia mechanical loading in anesthetized mice while monitoring heart parameters using electrocardiogram (ECG). An immediate, transient reduction in resting heart rate was observed during tibial loading in both adult male and female mice (p < 0.01) with concurrent increases in heart rate variability (HRV) (p < 0.01). ECG intervals, PR, QRS and QTc were unaffected with loading. In further studies, we found that at least 3 N of load was necessary to elicit this heart response in adult mice. With aging to 11-12 months the responsiveness of the heart to loading was blunted, suggesting this bone-heart connection may weaken with age. Administration of lidocaine around the tibia significantly diminished the heart rate response to bone loading (p < 0.05). Moreover, pre-treatment with sympathetic antagonist propranolol inhibited this heart rate response to loading (p < 0.05), while parasympathetic antagonist atropine did not (p > 0.05). This suggests that a neuronal afferent pathway in the hindlimb and reduction in efferent sympathetic tone mediate this bone-neuro-heart reflex. In conclusion, the findings that tibia bone loading age-dependently modulates heart function support the concept of physiological coupling of the skeletal and cardiovascular systems.

Development of a long-acting unbiased GIP receptor agonist for studies of GIP's role in bone metabolism

The incretin hormone glucose-dependent insulinotropic polypeptide (GIP) stimulates bone remodeling postprandially. Species variations complicate the development of long-acting agonists with similar effects on rodent and human GIP receptors (GIPR). We created a series of long-acting molecules suitable for rat studies based on human GIP, stabilized with Aib insertion in position 2, lipidations in the middle region (compounds 1-4: positions 14/16/17/20) or the C-terminus (compound 5: position 40), and elongation with an exendin-4 tail in the C-terminus (Cex). The compounds were tested in vitro on the human and rat GIPR for cAMP accumulation, beta-arrestin recruitment and internalization. Pharmacokinetic profiling in rats was completed for two compounds, and one was selected for bone remodeling studies in rats (measurements of C-terminal telopeptide (CTX) and procollagen type 1 N-propeptide). All five compounds retained the potency and efficacy of native (human and rat) GIP in cAMP accumulation and arrestin recruitment on human and rat GIPR with no differences in relative activities from native GIP. Only compound 3 induced internalization like species-matched GIP on respective receptors and was chosen for in vivo assessments in rats. Mean T1/2 was 9.1 h, and it decreased plasma levels of CTX compared to vehicle treatment following 1000 µg·kg-1 injections. In conclusion, the long-acting, unbiased compound 3 (hGIP(1-30-Cex)/Aib2/C16-diacid moiety in position 17), with retained activity for the human and rat GIPR, is suitable for bone remodeling studies in rats; hence, a useful tool compound for future research of GIP's therapeutic potential in bone-related diseases.

Ferroptosis-mediated immune responses in osteoporosis

Osteoporosis is a common systemic metabolic disease, characterized by decreased bone mass and susceptibility to fragility fractures, often associated with aging, menopause, genetics, and immunity. Ferroptosis plays an underestimated yet crucial role in the further impact of immune function changes on osteoporosis. Cell ferroptosis can induce alterations in immune function, subsequently influencing bone metabolism. In this context, this review summarizes several mechanisms of ferroptosis and introduces the latest insights on how ferroptosis regulates immune responses, exploring the interactions between ferroptosis and other mechanisms such as oxidative stress, inflammation, etc. This review elucidates potential treatment strategies for osteoporosis, emphasizing the promising potential of ferroptosis as an emerging target in the treatment of osteoporosis. In conclusion, preparations related to ferroptosis exhibit substantial clinical promise for enhancing bone mass restoration. The translational potential of this article: This review elucidates a nuanced conversation between the immune system and osteoporosis, with ferroptosis serving as the connecting link. These findings underscore the potential of ferroptosis inhibition as a therapeutic strategy for osteoporosis.

Risk of Osteoporosis Associated with Glucocorticoid Use in Pemphigus Vulgaris: Insights from a Retrospective Cohort Study

INTRODUCTION

Pemphigus vulgaris (PV) is an autoimmune bullous disease affecting the skin and mucous membranes. Osteoporosis, a significant side effect of commonly used glucocorticoids in treatment, can adversely contribute to the existing morbidity.

OBJECTIVES

This study aimed to assess the impact of glucocorticoid therapy on bone mineral density in patients with PV.

METHODS

Patients newly diagnosed with PV were included in this study. Femur and lumbar T-scores, serum calcium, vitamin D, alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) levels were analyzed before and one year after therapy.

RESULTS

Among 66 patients, the average time to diagnosis was 10.14 months, and the average daily dose of prednisone was 16.95 mg, with 63.6% of patients receiving medium doses. Our data showed no significant change in lumbar T-scores after one year of glucocorticoid treatment, but a significant decrease in femur density was observed. The decrease in femur T-scores was significant in the medium-dose group, while the lumbar T-scores decreased significantly in the high-dose group. There was no significant correlation between T-scores and sex, menopausal state, diagnosis time, or obesity. Additionally, vitamin D and LDH levels significantly increased after treatment, while changes in serum calcium and ALP levels were not significant.

CONCLUSION

Given the multiple factors that reduce bone mineral density in PV patients, the current strategies for glucocorticoid-induced osteoporosis prophylaxis in this group may need re-evaluation, with potential for additional recommendations to be included in pemphigus guidelines.

Global knowledge mapping of receptor activator of nuclear factor kappa-B ligand in osteoporotic fractures: a bibliometric analysis (2001-2024)

Background

Receptor activator of nuclear factor kappa-B ligand (RANKL) plays a critical role in bone metabolism and the pathogenesis of osteoporotic fractures. This study aims to conduct a bibliometric analysis of global research pertaining to RANKL and osteoporotic fractures to identify key trends, influential studies, and collaborative networks.

Methods

A literature search was conducted to identify articles found in the Web of Science Core Collection database regarding RANKL and osteoporotic fractures from 2001 to 2024. A bibliometric analysis was performed using VOSviewer, CiteSpace, and R 4.3.3 for the publication volume, country and institution contributions, journal impact, author influence, and research hotspots.

Results

A total of 214 articles were analyzed. Publication rates have steadily increased, with a peak of 21 papers in 2020. The U.S., China, and South Korea were the top contributing countries, and leading institutions included Harvard University and Dankook University. The Journal of Bone and Mineral Research, Osteoporosis International, and Bone were the journals of highest impact. At the level of authors, Heiss-Christian published the highest number and Christiansen-Claus had the strongest citation impact (1,368 citations). Research evolved from basic biological mechanisms (2001-2010) through clinical applications (2011-2017) to recent renewed interest in fundamental RANKL biology (2018-2024). Key research hotspots included postmenopausal osteoporosis, bone mineral density, and osteoclast differentiation, with emerging focus on RANKL's role beyond skeletal metabolism.

Conclusion

This bibliometric analysis provides a comprehensive overview of RANKL research in osteoporotic fractures, highlighting key priorities for future investigation. Future studies should prioritize understanding RANKL's broader physiological roles, developing better predictive markers, and optimizing personalized treatment strategies.

METTL3-mediated m6A modification of circSTAT6 modulates miR-188-3p/Beclin1 axis to promote osteogenic differentiation of mesenchymal stem cells

BACKGROUND

The role of N6-methyladenosine (m6A)-modified circRNAs in disease progression is of great significance. However, the specific impact of m6A modification of circSTAT6 on osteoporosis (OP) is still uncertain.

METHODS

The qRT-PCR was employed to assess the levels of METTL3, circSTAT6, miR-188-3p, and Beclin1. To investigate the interaction between miR-188-3p and circSTAT6 or Beclin, a dual-luciferase reporter assay was performed. To evaluate osteogenic differentiation in bone marrow mesenchymal stem cell (BMSC), western blot analysis was conducted to evaluate the protein expression of osteogenic markers, including ALP, OPN, and Runx2. In addition, alizarin red and alkaline phosphatase (ALP) staining assays were employed to assess osteogenesis.

RESULTS

The findings revealed that the downregulation of circSTAT6 was observed in OP. On the other hand, the overexpression of circSTAT6 was found to enhance the osteogenic differentiation of BMSC. In addition, the involvement of METTL3 in mediating m6A methylation of circSTAT6 was identified, which ultimately promoted osteogenesis. Furthermore, circSTAT6 functioned as an miR-188-3p sponge to regulate the expression of Beclin1. Further study revealed that the osteogenic-enhancing effect caused by circSTAT6 overexpression was counteracted by introducing a miR-188-3p mimic. Similarly, the osteogenic-promoting impact of the miR-188-3p inhibitor was reversed by suppressing Beclin1 expression.

CONCLUSIONS

The present study revealed, for the first time, that METTL3-mediated m6A modification of circSTAT6 regulated the miR-188-3p/Beclin1 axis to promote the osteogenic differentiation of BMSC. These findings offer a potential therapeutic target for the treatment of OP.

LncRNA H19 promotes osteoclast differentiation by sponging miR-29c-3p to increase expression of cathepsin K

BACKGROUND

Osteoporosis is a prevalent metabolic bone disease. Osteoporotic fractures can lead to severe functional impairment and increased mortality. Long noncoding RNA H19 has emerged as a pivotal player in bone remodeling, serving both as a biomarker and a regulator. While previous research has elucidated H19's role in promoting osteogenic differentiation through diverse mechanisms, its involvement in osteoclast differentiation remains largely unknown.

METHODS

In this study, we used lentiviral vectors to stably overexpress or knockdown H19 in RAW264.7 cell lines. Quantitative reverse polymerase chain reaction, Western blot, tartrate resistant acid phosphatase staining and bone resorption assay were performed to assess the level of osteoclast differentiation and bone resorption capacity. And fluorescence in situ hybridization, dual-luciferase reporter and RNA immunoprecipitation were used to explore the specific mechanism of H19 regulating osteoclast differentiation in vitro. Then, ovariectomized osteoporosis models in wild type mice and H19 knockout mice were conducted. And micro-CT analysis, HE staining, and immunohistochemistry were performed to verify the mechanism of H19 regulating osteoclast differentiation in vivo. Bone marrow derived monocytes and bone mesenchymal stem cells were extracted from mice and assayed for osteoclastic and osteogenic-related assays, respectively.

RESULTS

In vitro, H19 promoted osteoclast differentiation and bone resorption of RAW264.7 cells, while miR-29c-3p inhibited them. Both H19 and cathepsin K were the target genes of miR-29c-3p. In vivo, H19 knockout mice have increased femur bone mineral density, decreased osteoclast formation, and reduced cathepsin K expression. MiR-29c-3p agomir could increase bone mineral density in osteoporotic mice on the premise of H19 knockout.

CONCLUSIONS

H19 upregulates cathepsin K expression through sponging miR-29c-3p, which promoting osteoclast differentiation and enhancing bone resorption. This underscores the potential of H19 and miR-29c-3p as promising biomarkers for osteoporosis.

[Influencing fracture healing by specific osteoporosis medications]

BACKGROUND

Osteoporosis is a widespread disease defined by a reduction in bone mass and structure, thereby increasing the risk of fragility fractures. Treatment typically involves specific medications, which either inhibit bone resorption (antiresorptive) or stimulate bone formation (anabolic) and may potentially influence the healing of osteoporotic fractures. On the other hand, metabolic disorders, immune system dysfunctions or circulatory problems can impair fracture healing. Therefore, the targeted use of osteoporosis medications could be a strategy to promote the healing of impaired fractures.

OBJECTIVE

The aim of this study is to provide a current overview of the effects of osteoporosis medications approved in Germany on fracture healing. The focus is on the potential influence of these medications in the context of osteoporosis treatment. Additionally, the current state of research is examined to explore to what extent the targeted use of these medications could improve fracture healing.

MATERIAL AND METHODS

A literature search was conducted in the PubMed database using topic-specific keywords. Preclinical studies, clinical trials, review articles and meta-analyses were considered to present the current scientific knowledge with clinical relevance.

RESULTS

Preclinical and clinical studies suggest that specific osteoporosis medications do not have a clinically relevant negative impact on the healing of fragility fractures. Osteoanabolic substances even tend to have a positive effect on fracture healing in both normal and impaired healing processes; however, the available studies are limited and none of the medications have been approved for this specific use.

DISCUSSION

Osteoporosis medications with antiresorptive or osteoanabolic effects are primarily used to treat osteoporosis, especially after fragility fractures, to reduce the risk of further fractures. There is no clinically relevant impairment of fracture healing due to these medications. Further studies would be required to obtain approval for these medications specifically to improve fracture healing.

Protective Effect of Methyl Sulfonyl Methane on the Progression of Age-Induced Bone Loss by Regulating Oxidative Stress-Mediated Bone Resorption

Aging is associated with detrimental bone loss, often leading to fragility fractures, which may be driven by oxidative stress. In this study, the outcomes of comparing the differences among young, adult and aged C57BL/6J mice found that the trabecular bone volume was significantly lower in the aged mice compared to young mice, and the bone characteristics were significantly correlated with the oxidative status. To counteract the adverse effects of aging, methyl sulfonyl methane (MSM), a stable metabolite of dimethyl sulfoxide, was used to supplement the drinking water (400 mg/kg/day) of the aged mice (73 weeks old) for 8 weeks. The MSM supplementation improved the maximum load, bone microarchitecture, and mRNA levels of osteocyte-specific genes in the tibia. Furthermore, MSM reduced the serum level of the C-terminal telopeptide of type I collagen, a marker of bone resorption, and downregulated the mRNA levels of genes related to osteoclast proliferation and activity. MSM also decreased the levels of pro-inflammatory cytokines in both the serum and bone marrow. Importantly, the MSM-treated mice exhibited an enhanced antioxidant status, characterized by increased glutathione peroxidase (GPx) activity and glutathione concentration in plasma, erythrocytes and bone marrow. These improvements were linked to the activation of the nuclear factor E2 related factor 2 (Nrf2) pathway and its downstream antioxidant gene expression, including that of superoxide dismutase and GPx. These findings suggested that age-related bone loss is closely tied to oxidative stress, and MSM supplementation effectively reverses bone loss by mitigating oxidative stress-mediated bone resorption.

PRKD2 as a novel target for targeting the diabetes-osteoporosis nexus

Diabetes mellitus (DM) and osteoporosis (OP) co-morbidity (DMOP) pose major health challenges owing to their complex pathophysiological interactions. The aim of this study was to identify and validate key genes implicated in the pathogenesis of both conditions. By employing the Mfuzz time-series gene clustering method combined with transcriptome sequencing of patient serum, we systematically delineated gene expression patterns during the transition from a healthy state through DM to DMOP. These findings were further validated using external datasets, and a series of functional enrichment analyses, gene set enrichment analyses, and immune cell infiltration studies were conducted. Our analyses revealed a distinct progression pattern from a normal state through DM to DMOP, characterized by dynamic gene expression changes. Notably, PRKD2 emerged as a significantly downregulated gene in DMOP, highlighting its crucial role in disease pathogenesis. Further analyses revealed the involvement of PRKD2 in key signaling pathways, especially the Wnt and IL-18 pathways, which are critical for bone and glucose metabolism. Validation in cellular and animal models confirmed the role of PRKD2 in apoptosis and bone metabolism, emphasizing its therapeutic potential. In conclusion, our findings establish PRKD2 as a pivotal molecule in DMOP, offering fresh insights into its mechanisms and affirming its value as a therapeutic target.

A Pilot Study of the Gut Microbiota in Spine Fusion Surgery Patients

Background

The microbiome has been identified as a contributor to bone quality. As skeletal health is critical to success of orthopedic surgery, the gut microbiome may be a modifiable factor associated with postoperative outcomes. For spine fusion surgery in particular, de novo bone formation and sufficient bone mineral density are essential for successful outcomes. Given the prevalence and complexity of these procedures, the identification of novel factors that may be related to operative success is important.

Questions/purposes

We sought to investigate how the composition of the microbiota related to bone health in a focused spinal fusion surgery cohort.

Methods

We investigated the composition of the microbiome in a cohort of 31 patients prior to spinal fusion surgery, as well as changes in the microbiome over 6 weeks postoperatively. Preoperative areal bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry.

Results

Composition of gut microbiota differed among spinal fusion patients with low bone mass (T-score ≤ -1.0) and those with normal BMD (P = .03). There was no significant change in composition of the gut microbiota between preoperative evaluation and 6 weeks postoperatively.

Conclusions

Our findings in this small sample suggest there may be a relationship between BMD and composition of the gut microbiome in patients who undergo spinal fusion surgery. Further work is needed to investigate these relationships as well as potential interventions to foster a favorable microbial composition in spinal fusion surgery patients.

miR-208a-3p discriminates osteoporosis, predicts fracture, and regulates osteoclast activation through targeting STC1

BACKGROUND

Osteoporosis (OP) frequently occurs in post-menopausal women, increasing the risk of fracture. Early screening OP could improve the prevention of fractures.This study focused on the significance of miR-208a-3p in diagnosing OP and development regulation, aiming to explore a novel biomarker and therapeutic target for OP.

METHODS

The study enrolled a total of 154 post-menopausal women and grouping was performed based on the incidence of OP and fracture. The significance of miR-208a-3p was evaluated from the perspectives of menopausal correlation, OP diagnosis, and fracture prediction. In mechanism, the regulatory effect and mechanism of miR-208a-3p on osteoclast activation was investigated.

RESULTS

miR-208a-3p was menopause-related showing a negative correlation with E2 and positive correlations with FSH and LH. Significant upregulation of miR-208a-3p was observed in post-menopausal women with OP and showed significant diagnostic potential. Increasing miR-208a-3p was positively correlated with bone metabolism markers and negatively correlated with BMD of post-menopausal women with OP. Moreover, miR-208a-3p was also identified as a risk factor for fracture. STC1 was identified as a direct target of miR-208a-3p and was negatively regulated by miR-208a-3p. Silencing miR-208a-3p significantly alleviated macrophage inflammation and osteoblast activation, which was reversed by the knockdown of STC1.

CONCLUSION

Serum miR-208a-3p served as a diagnostic biomarker for OP and a risk factor for fracture in post-menopausal women. miR-208a-3p regulated macrophage inflammation and further mediated osteoclast activation via targeting STC1.

Hyperbaric Oxygen Therapy for the Treatment of Bone-Related Diseases

Hyperbaric oxygen therapy (HBOT) is a therapeutic modality that enhances tissue oxygenation by delivering 100% oxygen at pressures greater than 1 absolute atmosphere. In recent years, HBOT has shown considerable potential in the treatment of bone diseases. While excess oxygen was once thought to induce oxidative stress, recent studies indicate that when administered within safe limits, HBOT can notably promote bone healing and repair. Extensive basic research has demonstrated that HBOT can stimulate the proliferation and differentiation of osteoblasts and encourage bone angiogenesis. Furthermore, HBOT has been shown to exert a beneficial influence on bone metabolism by modulating the inflammatory response and redox status. These mechanisms are closely related to core issues of bone biology. Specifically, in the context of fracture healing, bone defect repair, and conditions such as osteoporosis, HBOT targets the key bone signaling pathways involved in bone health, thereby exerting a therapeutic effect. Several clinical studies have demonstrated the efficacy of HBOT in improving bone health. However, the optimal HBOT regimen for treating various bone diseases still requires further definition to expand the indications for its clinical application. This paper outlines the mechanisms of HBOT, focusing on its antioxidant stress, promotion of bone vascularization, and anti-inflammatory properties. The paper also describes the application of HBOT in orthopedic diseases, thereby providing a scientific basis for the development of precise and personalized HBOT treatment regimens in clinical orthopedics.

Ketogenic diet and β-hydroxybutyrate in osteoporosis: current progress and controversy

Diet has been proven to have significant impacts on the pathogenesis and treatment of osteoporosis. This review attempts to elucidate the current progress and controversy surrounding the ketogenic diet (KD) and β-hydroxybutyrate (BHB) in osteoporosis and offers a novel perspective on the prevention and treatment of osteoporosis. The ketogenic diet has been broadly used in the treatment of epilepsy, diabetes, obesity, and certain neoplasms by triggering ketone bodies, mainly BHB. However, in most osteoporosis-related clinical and preclinical studies, the ketogenic diet has demonstrated the detrimental effects of inhibiting bone accumulation and damaging bone microarchitecture. In contrast, BHB is thought to ameliorate osteoporosis by promoting osteoblastogenesis and inhibiting osteoclastogenesis. The main purpose of this review is to summarize the current research progress and hope that more basic and clinical experiments will focus on the similarities and differences between ketogenic diet (KD) and BHB in osteoporosis.

Quercetin promotes osteogenic differentiation of bone marrow mesenchymal stem cells by modulating the miR-214-3p/Wnt3a/β-catenin signaling pathway

Postmenopausal osteoporosis, primarily driven by estrogen deficiency, is predominantly mediated through estrogen receptors such as ERα. However, the underlying mechanisms necessitate further investigation. In this study, we established an ERα-deficient model in rBMSCs to elucidate the role of ERα in osteogenic differentiation and miRNA expression profiles. Our findings demonstrate that knockdown of ERα inhibits osteogenic differentiation in rBMSCs, resulting in upregulation of 25 miRNAs and downregulation of 184 miRNAs, including a significant increase in the expression of miR-214-3p. Validation using qPCR, Western blotting, and bioinformatics analysis revealed that miR-214-3p negatively regulates osteogenic differentiation via the Wnt/β-catenin signaling pathway. Furthermore, we explored the potential therapeutic effects of quercetin (QUE) on rBMSCs. CCK8, alkaline phosphatase activity assays, and Alizarin Red staining demonstrated that QUE dose-dependently enhances rBMSCs proliferation, alkaline phosphatase activity, and mineralization within the concentration range of 0.1-1 μM. Importantly, QUE was found to downregulate miR-214-3p expression and activate the Wnt3a/β-catenin signaling pathway. Rescue experiments confirmed that QUE could counteract the inhibitory effects of miR-214-3p on the Wnt3a/β-catenin signaling pathway. Collectively, our study provides compelling evidence that knockdown of ERα inhibits the osteogenic differentiation of rBMSCs by affecting the miRNA expression profile, while QUE can reverse the inhibitory effect exerted by miR-214-3p on the Wnt3a/β-catenin signaling pathway, thereby offering novel insights into diagnosis, prevention, and treatment strategies for postmenopausal osteoporosis.

Diagnostic value and fracture healing-preventing effect of upregulated microRNA-4534 in patients with osteoporotic fractures

BACKGROUND

Osteoporosis fracture is a common and most serious complication of osteoporosis.

HYPOTHESIS

This study sought to assess the level, the diagnostic potential, and the effect of circulating miR-4534 in osteoporotic fractures.

METHODS

GSE74209 and GSE93883 were analyzed using GEO2R online tool for differentially expressed microRNAs in osteoporotic fractures. Postmenopausal women were recruited and serum samples were determined by RT-qPCR for level of miR-4534. ROC curves were plotted to evaluate the diagnostic value of miR-4534 in osteoporotic fractures. The effects of miR-4534 on hFOB 1.19 osteogenic marker levels, proliferation, and migration were measured by RT-qPCR, CCK-8 assay and Transwell assay, respectively. The target gene for miR-4534 was predicted and rescue experiments were conducted.

RESULTS

miR-4534 was identified as an upregulated miR in osteoporotic fracture. Up-regulated miR-4534 had the potential to distinguish osteoporotic fracture from health, and from common osteoporosis. The up-regulated miR-4534 in hFOB 1.19 cocultured with human umbilical vein endothelial cells could inhibit cell osteogenic marker levels, proliferation and migration. CFTR was a target gene of miR-4534 and rescued the suppression of miR-4534 on hFOB 1.19 activity.

CONCLUSIONS

MiR-4534 is a new potential diagnostic biomarker for osteoporotic fractures. MiR-4534 can regulate osteoblast differentiation, proliferation, and migration by targeting CFTR.

LINC01271 promotes fracture healing via regulating miR-19a-3p/PIK3CA axis

OBJECTIVE

Osteoporosis increases the risk of fragility fractures, impacting patients' lives. This study aimed to investigate whether LINC01271 was involved in the process of fragility fractures and healing, providing a new perspective for its diagnosis and treatment.

METHODS

This study included 94 healthy individuals, 82 patients with osteoporosis, and 85 patients with fragility fractures as subjects. RT-qPCR was used to measure the levels of LINC01271, miR-19a-3p, PIK3CA, and osteogenic differentiation markers in osteoblasts and subjects' serum. Luciferase reporter assays, RIP experiments, and RNA pull-down assays were utilized to verify the target relationships between LINC01271 and miR-19a-3p, as well as between miR-19a-3p and PIK3CA. Cell proliferation and apoptosis were assessed using CCK-8 assays and flow cytometry.

RESULTS

Compared to the healthy control group, the serum levels of LINC01271 were significantly reduced in patients with osteoporosis and fragility fractures. Furthermore, LINC01271 levels increased with time-dependent fracture healing. In vitro studies indicated that LINC01271 boosted osteoblast proliferation, inhibited apoptosis, and augmented osteogenic differences, whereas its inhibition reverses their effects. LINC01271 and PIK3CA were identified as targets of miR-19a-3p, and overexpression of miR-19a-3p could antagonize the effect of LINC01271 in promoting fracture healing.

CONCLUSION

The results indicated that LINC01271 may play a key role in osteoblast function and fracture healing through its interaction with miR-19a-3p and regulation of PIK3CA.

Unlocking the therapeutic potential of WISP-1: A comprehensive exploration of its role in age-related musculoskeletal disorders

As the global population ages, the incidence of age-related musculoskeletal diseases continues to increase, driven by numerous complex and poorly understood factors. WNT-1 inducible secreted protein 1 (WISP-1), a secreted matrix protein, plays a critical role in the growth and development of the musculoskeletal system, including chondrogenesis, osteogenesis, and myogenesis. Numerous in vivo and in vitro studies have demonstrated that WISP-1 is significantly upregulated in age-related musculoskeletal conditions, such as osteoarthritis, osteoporosis, and sarcopenia, suggesting its involvement in the pathogenesis of these diseases. Regulating WISP-1 expression holds promise as a therapeutic strategy for improving musculoskeletal function, potentially offering new avenues for treating age-related musculoskeletal diseases in clinical practice. This review highlights the signaling pathways associated with WISP-1, its physiological roles within the musculoskeletal system, and its therapeutic potential in treating age-related musculoskeletal disorders.

Association of serum fatty acids with bone health in rural elderly population in Qingdao, China: A cross-sectional study

As a type of macronutrient, fatty acids (FA) play significant roles in the bone health of elderly people. However, the specific association between different types of FA and bone health is not fully understood, especially in rural elderly populations. To address this gap, a study was conducted in rural areas of Qingdao, China. Participants aged 65 and older were randomly recruited from 11 rural villages in Licha town, Qingdao City. The levels of serum FA in their serum were measured to investigate the associations between FA and bone mass. The results showed that levels of saturated fatty acids (SFA), n-3 polyunsaturated fatty acids (n-3 PUFA), and n-6 polyunsaturated fatty acids (n-6 PUFA) were all significantly associated with bone mass. Specifically, higher levels of SFA were positively correlated with low bone mass (LBM), while PUFA levels were inversely correlated with LBM. Furthermore, the odds ratio (OR) for LBM exhibited a significant nonlinear dose-response relationship (pnonlinearity = 0.1989) with SFA levels, and a significant nonlinear dose-dependent relationship was also observed with the levels of n-3PUFA and n-6PUFA (pnonlinearity = 0.6183, 0.5808, respectively), indicating that increasing dietary PUFA intake appropriately and controlling SFA intake may benefit the bone health of elderly individuals in rural areas.

Differential Regulatory Effects of Probiotics on Bone Metabolism by the Status of Bone Health and Delivery Route

Probiotics are known to have favorable effects on human health. Nevertheless, probiotics are not always beneficial and can cause unintended adverse effects such as bacteremia and/or inflammation in immunocompromised patients. In the present study, we investigated the effects of probiotics on the regulation of bone metabolism under different health conditions and delivery routes. Intragastric administration of Lactiplantibacillus plantarum to ovariectomized mouse models for mimicking post-menopausal osteoporosis in humans substantially ameliorated osteoporosis by increasing bone and mineral density. In contrast, such effects did not occur in normal healthy mice under the same condition. Interestingly, however, intraperitoneal administration of L. plantarum induced bone destruction by increasing osteoclast differentiation and decreasing osteoblast differentiation. Furthermore, when L. plantarum was implanted into mouse calvarial bone, it potently augmented bone resorption. Concordantly, L. plantarum upregulated osteoclastogenesis and downregulated osteoblastogenesis in in vitro experiments. These results suggest that L. plantarum can have distinct roles in the regulation of bone metabolism depending on bone health and the delivery route.

Safety evaluation of medroxyprogesterone acetate: a pharmacovigilance analysis using FDA adverse event reporting system data

Background

Medroxyprogesterone acetate (MPA), a synthetic progestogen, is extensively used for the treatment of various conditions, including contraception, irregular menstruation, functional uterine bleeding, and endometriosis. However, like all pharmaceutical agents, MPA is associated with adverse drug reactions. This study aimed to evaluate the adverse events (AEs) associated with MPA in by analyzing real-world data from the U.S. Food and Drug Administration's Adverse Event Reporting System (FAERS). By providing a comprehensive assessment of the safety profile of MPA, this study seeks to support informed clinical decision-making.

Methods

Data covering the period from the first quarter of 2004 to the first quarter of 2024 were collected from the FAERS database. Disproportionality analyses were conducted using several statistical methods, including reporting odds ratio (ROR), proportional reporting ratio (PRR), empirical Bayesian geometric mean (EBGM). Additionally, time-to-onset (TTO) analysis was employed to quantify the signals of the MPA-associated AEs.

Results

A comprehensive dataset comprising 21,035,995 AE reports was compiled. Among these, 3,939 women reported using MPA as a contraceptive method. The reports covered 27 system organ classes (SOCs) and 25 high-frequency AE signals. Notably, significant AEs were identified, some of which were not previously detailed in the medication's prescribing information. Unforeseen significant AEs such as unintended pregnancy (n = 623; ROR, 6.65; ROR025, 6.1; χ2, 2,482.38; PRR, 6.41; EBGM, 5.69; EBGM05, 5.29), bone pain (n = 35; ROR, 13.78; ROR025, 9.4; χ2, 311.2; PRR, 13.75; EBGM, 10.59; EBGM05, 7.69), gait disturbance (n = 34; ROR, 2.82; ROR025, 1.99; χ2, 37.31; PRR, 2.88; EBGM, 2.7; EBGM05, 2.02), dental caries (n = 15; ROR, 23.16; ROR025, 12.32; χ2, 204.26; PRR, 23.14; EBGM, 15.23; EBGM05, 8.98), decrease in blood pressure (n = 15; ROR, 3.88; ROR025, 2.29; χ2, 29.35; PRR, 3.88; EBGM, 3.63; EBGM05, 2.33), and osteonecrosis (n = 9; ROR, 23.44; ROR025, 10.36; χ2, 123.67; PRR, 23.43; EBGM, 15.35; EBGM05, 7.75) were identified as AEs that were not previously outlined in the prescribing information of the medication.

Conclusion

Our findings align with clinical observations, highlighting the emergence of previously unreported AE signals associated with MPA and their demographic and TTO characteristics. Further pharmaco-epidemiological studies are required to substantiate these observations.

NLRP3 blockade by MCC950 suppressed osteoclastogenesis via NF-κB/c-Fos/NFATc1 signal pathway and alleviated bone loss in diabetes mellitus

Obesity and type 2 diabetes mellitus (T2DM) are linked to osteoporosis development, with obesity being a significant risk factor for T2DM. T2DM patients with obesity exhibit a higher fracture rate and often have a poor prognosis post-fracture. To address the urgent need for understanding the mechanisms of diabetic osteoporosis (DOP), research is ongoing to explore how obesity and T2DM impact bone metabolism. The NLRP3 inflammasome has been implicated in the pathogenesis of osteoporosis, and MCC950, an NLRP3 inflammasome inhibitor, has shown promise in various diseases but its role in osteoporosis remains unexplored. In this study, BMMs and BMSCs were isolated and cultured to investigate the effects of MCC950 on bone metabolism, and DOP model was used to evaluate the efficacy of MCC950 in vivo. The study demonstrated that MCC950 treatment inhibited osteoclast differentiation, reduced bone resorption capacity in BMMs without suppression for osteoblast differentiation from BMSCs. Additionally, MCC950 suppressed the activation of the NF-κB signaling pathway and downregulated key factors associated with osteoclast differentiation. Additionally, MCC950 alleviated bone loss in DOP mouse. These findings suggest that MCC950, by targeting the NLRP3 inflammasome, may have a protective role in preventing osteoporosis induced by T2DM with obesity. The study highlights the potential therapeutic implications of MCC950 in managing diabetic osteoporosis and calls for further research to explore its clinical application in high-risk patient populations.

Characteristics and outcomes of inpatients aged 85 and older with thoracolumbar vertebral fractures: impact on hospital stay and mortality

BACKGROUND

There is a gap in evidence about medical outcomes in oldest-old patients (aged 85 and older) with vertebral fractures (VFs). The aim of this study was to evaluate the impact of patient and fracture characteristics on "short-term" hospital outcomes.

METHODS

All patients aged ≥ 85 presenting an acute or subsequent VF at our single level I spine center between 2019 and 2021 requiring hospital treatment were included. The data collection was conducted retrospectively. The primary parameters of interest were length of stay (LOS) and in-hospital mortality. Further outcome parameters were the occurrence of general (non-operative) complications and Intensive Care Unit (ICU) admission. For statistical analysis, linear and binary logistic regression modeling were performed.

RESULTS

A total of 153 patients with an average age of 88.5 (range 85 to 99) met the inclusion criteria. Our patients were mostly female (68.6%) and moderately comorbid according to a Charlson Comorbidity Index (CCI) of 2.9. 58.8% had diagnosed osteoporosis. Fracture morphologies represented as "Osteoporotic Fracture" (OF) classification types were of central importance for undergoing operative treatment (OP) (p < 0.001), necessity for intensive care (p = 0.023), LOS (p = 0.014), and mortality (p = 0.018). 38.6% had OP. We recorded a complication rate of 59.5%, which highly influenced (p < 0.001) both primary outcome parameters. Overall, patients stayed 14.6 days with a mortality of 11.1%.

CONCLUSION

VFs are a severe event in oldest-old patients with a crucial risk of poor medical outcomes during hospitalization. The fracture morphologies are of central importance. However, little is known about the hospital stay of oldest-old inpatients with VFs. Considering an aging population, further investigations would be recommended.

Efficacy of traditional Chinese exercise on postmenopausal osteoporosis: a systematic review and meta-analysis

BACKGROUND

Traditional Chinese exercise (TCE) is used as a therapeutic method in patients with postmenopausal osteoporosis. A meta-analysis was performed to evaluate the efficacy of TCE and provide reliable clinical evidence.

METHODS

Eight databases, including the Cochrane Library, PubMed, Embase, Web of Science, Chinese Science Citation Database, Wanfang, China National Knowledge Infrastructure, and Chinese Medical Journal full-text databases, were searched for randomized controlled trials. Meta-analysis was performed using the RevMan (version 5.4) software.

RESULTS

Sixteen studies involving 1,288 patients were included. Compared with conventional treatment alone, TCE improved patients' bone mineral density, decreased pain, improved balance, improved quality of life, and decreased deoxypyridinoline levels. However, the intervention effects on the biochemical indexes of bone metabolism, including blood calcium, blood phosphorus, osteocalcin, and alkaline phosphatase levels, were not statistically significant.

CONCLUSION

TCE has a significant effect on postmenopausal patients with osteoporosis and can be used as a non-pharmacological treatment. The results of this study should be interpreted with caution because of the large heterogeneity for some indicators.

Beyond the Surface: Uncovering Secondary Causes of Osteoporosis for Optimal Management

Osteoporosis (OP), a condition marked by reduced bone mineral density and increased fracture risk, can arise either as a primary disorder or secondary to other diseases and medications. While primary OP typically relates to age-related or postmenopausal changes, secondary OP results from underlying conditions or drug exposures, complicating diagnosis and management. This review explores the pathophysiology, prevalence, and treatment approaches for secondary OP arising from endocrine, renal, gastrointestinal, hematological, and autoimmune disorders, as well as medication side effects. The findings highlight that secondary OP is frequently undiagnosed, particularly in premenopausal women and men, with conditions such as chronic kidney disease, glucocorticoid use, and diabetes among the primary contributors. Management strategies must be tailored to address the underlying conditions to effectively reduce fracture risk and improve outcomes. Ultimately, this review underscores the necessity for increased clinical awareness and more targeted interventions for optimal management of secondary OP.

Sonification of Deproteinized Bovine Bone Functionalized with Genistein Enhances Bone Repair in Peri-Implant Bone Defects in Ovariectomized Rats

Estrogen deficiency is one of several contributing factors to catabolic changes in bone surrounding dental implants, impairing bone repair in defects requiring bone regeneration. Functionalizing bone substitutes is an alternative approach among various strategies to address this challenge. In this study, the aim was to evaluate the effect of functionalizing deproteinized bovine bone (Bio-Oss®, BO) with genistein via sonication on peri-implant bone defects in ovariectomized rats. The animals were randomly distributed according to the treatment into the following four groups (n = 10): BO sonicated with genistein (BOS + GEN), BO sonicated alone (BOS), untreated BO (BO), and blood clot only (CLOT). After twenty-eight days, implant removal torque was determined, and the peri-implant bone parameters were calculated based on computed microtomography. Additionally, the gene expression of bone turnover markers was evaluated. As a main result, the functionalization with genistein increased implant removal torque and the peri-implant bone volume in the BOS + GEN group compared to both BOS and BO groups (both p < 0.05). These findings suggest that the sonification of deproteinized bovine bone functionalized with genistein improves bone repair in peri-implant bone defects in ovariectomized rats.

Niacin regulates glucose metabolism and osteogenic differentiation via the SIRT2-C/EBPβ-AREG signaling axis

The pathogenesis of osteoporosis is driven by several mechanisms including the imbalance between osteoblastic bone formation and osteoclastic bone resorption. Currently, the role of Niacin (NA), also known as vitamin B3, in the regulation of osteoblastic differentiation is not fully understood. Data from the NHANES database were employed to investigate the association of NA intake with the prevalence of osteoporosis. Alterations in mRNA and protein levels of genes and proteins involved in osteogenic differentiation were evaluated via techniques including qRT-PCR, protein immunoblotting, Alkaline Phosphatase (ALP) activity analysis, ALP staining, and Alizarin Red staining. Changes in the mouse skeletal system were investigated by organizational analysis and Micro-CT. The results indicated that NA promoted osteogenic differentiation. Co-immunoprecipitation and chromatin immunoprecipitation were performed to explore the underlying mechanisms. It was observed that NA promoted AREG expression by deacetylating C/EBPβ via SIRT2, thereby activating the PI3K-AKT signaling pathway. It also enhanced the activity of the pivotal glycolytic enzyme, PFKFB3. This cascade amplified osteoblast glycolysis, facilitating osteoblast differentiation. These findings demonstrate that NA modulates glucose metabolism and influences osteogenic differentiation via the SIRT2-C/EBPβ-AREG pathway, suggesting that NA may be a potential therapeutic agent for the management of osteoporosis, and AREG could be a plausible target.

Association between sedentary behavior and bone mass, microstructure and strength in children, adolescents and young adults: a systematic review

Sedentary behavior (SED) research is currently receiving increasing attention in the field of public health. While it has been shown to have negative effects on cardiovascular or metabolic health, there is limited knowledge regarding the relationship between SED and bone health in children, adolescents, and young adults. Thus, the purpose of this review is to investigate the associations between SED and bone health status, specifically bone mass, microstructure, and strength. A comprehensive literature search was conducted across five electronic databases, including EMBASE, PubMed, Medline, Cochrane, Web of Science and CNKI. The inclusion criteria were as follows: healthy participants aged 24 years or younger, with measured SED and measured bone outcomes. The quality of the included articles was assessed using the National Institute of Health Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. After excluding, the final sample included 25 cross-sectional, 9 observational and 2 both cross-sectional and longitudinal studies. Among these, seven were rated as 'high quality', twenty-three were rated as 'moderated quality', and six were rated as 'low quality' according to the quality assessment criteria. After summarizing the evidence, we found no strong evidence to support an association between BMC or BMD and SED, even when considering gender or adjusting for moderate-to-vigorous physical activity (MVPA). However, a strong level of evidence was found indicating a negative relationship between objectively measured SED and cortical bone mineral density (Ct.BMD) in the tibia or stiffness index (SI) in the Calcaneus across all age groups. While the association between adverse bone health outcomes and SED still cannot be confirmed due to insufficient evidence, these findings suggest that bone microstructure and strength may be more sensitive to SED than bone mass. Thus, further evidence is needed to fully understand the connection between sedentary behavior and bone health, particularly regarding the relationship between SED and bone strength.

Increased Risk of Osteoporotic Vertebral Compression Fractures Following Epidural Steroid Injections in Patients with Lumbar Degenerative Disease: A Retrospective Cohort Study

Background/Objectives: Lumbar degenerative disease is a common age-related condition, with epidural steroid injection (ESI) being a widely employed conservative treatment approach. However, the potential effect of ESI on osteoporosis and fracture risk remains unclear. This study investigated the risk of osteoporotic vertebral compression fractures (OVCFs) in patients with lumbar degenerative disease who underwent ESI treatment. Methods: A cohort of 64 patients who received ESI treatment and a control group of 256 patients were included in this study. Demographic data, clinical characteristics, and follow-up information were collected. Cox proportional hazards models were used to analyze risk factors for OVCF, and subgroup analyses were conducted. Results: OVCF was more common in the ESI group than in the control group (hazard ratio [HR]: 3.49, 95% confidence interval [CI]: 1.06-11.43, p = 0.039). After confounding factors were adjusted for, ESI remained an independent risk factor for OVCF (HR: 4.60, 95% CI: 1.01-20.89, p = 0.048). In a subgroup analysis, lower socioeconomic status was associated with higher OVCF risk (HR: 11.82, 95% CI: 1.06-131.26, p = 0.044). The ESI group had improved short-term pain relief, with nonsignificant long-term effects. Conclusions: Patients with lumbar degenerative disease receiving ESI treatment are at an increased risk of OVCF, particularly those with lower socioeconomic status. These findings underscore the importance of regular bone density monitoring and fracture prevention following ESI treatment. Clinicians should carefully weigh the short-term benefits of ESI against the long-term risks and develop individualized follow-up plans for high-risk patients.

ALKBH5 regulates etoposide-induced cellular senescence and osteogenic differentiation in osteoporosis through mediating the m6A modification of VDAC3

Osteoporosis, a common bone disease in older individuals, involves the progression influenced by N6-methyladenosine (m6A) modification. This study aimed to elucidate the effects of VDAC3 m6A modification on human bone mesenchymal stromal cell (BMSC) senescence and osteogenic differentiation. BMSCs were treated with etoposide to induce senescence. Senescence was assessed by β-galactosidase staining and quantitative real-time PCR (qPCR), and osteogenic differentiation was evaluated using Western blot, alkaline phosphatase, and alizarin red S staining. VDAC3 and ALKBH5 expression were quantified by qPCR, and their interaction was assessed by RNA immunoprecipitation (RIP) and luciferase reporter assay. m6A methylation was analyzed using the Me-RIP assay. VDAC3 expression was significantly decreased in etoposide-treated BMSCs (1.00 ± 0.13 vs. 0.26 ± 0.06). VDAC3 overexpression reduced etoposide-induced senescence and promoted osteogenic differentiation. ALKBH5 overexpression inhibited VDAC3 m6A modification (1.00 ± 0.095 vs. 0.233 ± 0.177) and its stability. ALKBH5 knockdown decreased etoposide-induced senescence and promoted osteogenic differentiation, effects that were reversed by VDAC3 knockdown. YTHDF1 was identified as the m6A methylation reader, and its overexpression inhibited VDAC3 stability. We demonstrated that ALKBH5 inhibited osteogenic differentiation of etoposide-induced senescent cells through the inhibition of VDAC3 m6A modification, and YTHDF1 acted as the m6A methylation reader. These findings provide a novel theoretical basis for the treatment of osteoporosis.

Part II: A new perspective for modeling the bone remodeling process: Biology, mechanics, and pathologies

In this paper, we explore the effects of biological (pathological) and mechanical damage on bone tissue within a benchmark model. Using the Finite Element Methodology, we analyze and numerically test the model's components, capabilities, and performance under physiologically and pathologically relevant conditions. Our findings demonstrate the model's effectiveness in simulating bone remodeling processes and self-repair mechanisms for micro-damage induced by biological internal conditions and mechanical external ones within bone tissue. This article is the second part of a series, where the first part presented the mathematical model and the biological and physical significance of the terms used in a simplified benchmark model. It explored the bone remodeling model's application, implementation, and results under physiological conditions.

Osteoporosis in postmenopausal women is associated with disturbances in gut microbiota and migration of peripheral immune cells

BACKGROUND

Postmenopausal osteoporosis (PMO) results from a reduction in bone mass and microarchitectural deterioration in bone tissue due to estrogen deficiency, which may increase the incidence of fragility fractures. In recent years, the "gut-immune response-bone" axis has been proposed as a novel potential approach in the prevention and treatment of PMO. Studies on ovariectomized murine model indicated the reciprocal role of Th17 cells and Treg cells in the aetiology of osteoporosis. However, the relationship among gut microbiota, immune cells and bone metabolic indexes remains unknown in PMO.

METHODS

A total of 77 postmenopausal women were recruited for the study and divided into control (n = 30), osteopenia (n = 19), and osteoporosis (n = 28) groups based on their T score. The frequency of Treg and Th17 cells in lymphocytes were analyzed by flow cytometry. The serum levels of interleukin (IL)-10, 17 A, 1β, 6, tumor necrosis factor (TNF)-α, and lipopolysaccharide (LPS) were determined via enzyme-linked immunosorbent assay. Additionally, 16S rRNA gene V3-V4 region sequencing analysis was performed to investigate the gut microbiota of the participants.

RESULTS

The results demonstrated decreased bacterial richness and diversed intestinal composition in PMO. In addition, significant differences of relative abundance of the gut microbial community in phylum and genus levels were found, mainly including increased Bacteroidota, Proteobacteria, and Campylobacterota, as well as reduced Firmicutes, Butyricicoccus, and Faecalibacterium. Intriugingly, in the osteoporosis group, the concentration of Treg cells and associated IL-10 in peripheral circulation was negatively regulated, while other chronic systemic proinflammatory cytokines and Th17 cells showed opposite trends. Moreover, significantly elevated plasma lipopolysaccharide (LPS) in patients with osteoporosis indicated that disrupted intestinal integrity and permeability. A correlation analysis showed close relationships between gut bacteria and inflammation.

CONCLUSIONS

Collectively, these observations will lead to a better understanding of the relationship among bone homeostasis, the microbiota, and circulating immune cells in PMO. The elevated LPS levels of osteoporosis patients which not only indicate a breach in intestinal integrity but also suggest a novel biomarker for assessing osteoporosis risk linked to gut health.

The association between body roundness index and osteoporosis in American adults: analysis from NHANES dataset

Background

An innovative way to quantify obesity that appropriately captures levels of visceral and body fat is the Body Roundness Index (BRI). The purpose of this study is to look at the relationship between BRI and osteoporosis (OP) in adult Americans.

Methods

This study utilized data from the National Health and Nutrition Examination Survey (NHANES) collected between 2007 and 2018. NHANES is a research program designed to assess the health and nutritional status of adults and children in the United States. It conducts surveys focusing on various populations and health-related topics. Logistic regression analysis was employed to investigate the relationship between BRI and OP, adjusting for various covariates. BRI was categorized into four levels to further explore the association trends between different BRI levels and OP, enhancing the robustness of the results. Using restricted cubic spline (RCS) analysis, the dose-response relationship between BRI and OP was illustrated. Subgroup analyses were also carried out to evaluate the consistency and robustness of the findings.

Results

This study included 8,899 participants aged 50 years and older, among whom 763 had OP. BRI and the prevalence of OP were inversely correlated in the fully adjusted model (OR = 0.79, 95% CI: 0.69-0.86). The prevalence of OP considerably reduced with higher BRI levels when BRI was converted from a continuous to a categorical variable in comparison to the lowest BRI quartile. RCS analysis revealed an L-shaped negative correlation between BRI and OP prevalence, with a threshold effect analysis identifying a breakpoint at BRI = 5.29. Each unit increase in BRI to the left of this breakpoint was linked to a 36% decrease in the probability of OP (OR = 0.64, 95% CI: 0.57-0.72). Based on stratified factor subgroup analyses, it was shown that the negative correlation between BRI and OP persisted.

Conclusion

In a large, representative sample of American adults, this study identified a significant negative correlation between BRI and the prevalence of OP. Specifically, as BRI increases, the prevalence of osteoporosis decreases. Maintaining an appropriate and healthy BRI level may play a critical role in the prevention of osteoporosis. Therefore, regular monitoring of BRI and the adoption of appropriate health measures are essential for reducing the risk of osteoporosis.

LINC00963 Represses Osteogenic Differentiation of hBMSCs via the miR-10b-5p/RAP2A/AKT Axis

Osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs) is important for human bone formation. Long non-coding RNAs (lncRNAs) are critical regulators in osteogenic differentiation. This study aimed to explore the function and mechanisms of long intergenic non-protein coding RNA 963 (LINC00963) in affecting osteogenesis. Cell differentiation was assessed by alkaline phosphatase (ALP) activity detection and ALP staining assay. Meanwhile, levels of osteogenic marker genes, including RUNX family transcription factor 2 (RUNX2), osteocalcin (OCN), and osteopontin (OPN), were detected by RT-qPCR and western blot. Cell proliferation and apoptosis were measured using CCK-8 assay and flow cytometry analysis. RNA immunoprecipitation (RIP), RNA pull-down and luciferase reporter assays were used to investigate the interaction between genes. LINC00963 expression was down-regulated in hBMSCs treated with osteogenic induction. LINC00963 overexpression inhibited hBMSCs differentiation, proliferation, and elevated apoptosis. LINC00963 acted as a competing endogenous RNA (ceRNA) to interact with miR-10b-5p and thereby regulated the expression level of Ras-related protein Rap-2a (RAP2A). LINC00963 regulated RAP2A to inhibit the level of phosphorylated AKT (p-AKT). LINC00963 inhibited hBMSCs differentiation, proliferation, and elevated apoptosis via the miR-10b-5p/RAP2A/AKT signaling, which might help improve the treatment of osteoporosis.

Bencaosome [16:0 Lyso PA+XLGB28-sRNA] improves osteoporosis by simultaneously promoting osteogenesis and inhibiting osteoclastogenesis in mice

Osteoporosis (OP) is a systemic metabolic bone disease resulting in reduced bone strength and increased susceptibility to fractures, making it a significant public health and economic problem worldwide. The clinical use of anti-osteoporosis agents is limited because of their serious side effects or the high cost of long-term use. The Xianlinggubao (XLGB) formula is an effective traditional Chinese herbal medicine commonly used in orthopedics to treat osteoporosis; however, its mechanism of action remains unclear. In this study, we screened 40 small RNAs derived from XLGB capsules and found that XLGB28-sRNA targeting TNFSF11 exerted a significant anti-osteoporosis effect in vitro and in vivo by simultaneously promoting osteogenesis and inhibiting osteoclastogenesis. Oral administration of bencaosome [16:0 Lyso PA+XLGB28-sRNA] effectively improved bone mineral density and reduced the damage to the bone microstructure in mice. These results suggest that XLGB28-sRNA may be a novel oligonucleotide drug that promotes osteogenesis and inhibits osteoclastogenesis in mice.

TRIM16 mitigates impaired osteogenic differentiation and antioxidant response in D-galactose-induced senescent osteoblasts

Senile osteoporosis (SOP), characterized by significant bone loss, poses a substantial threat to elderly skeletal health, with oxidative stress playing a crucial role in its pathogenesis. Although Tripartite Motif 16 (TRIM16) has been identified as a promoter of antioxidant response and osteogenic differentiation, its regulatory role in SOP remains incompletely understood. This study aims to elucidate the underlying mechanism of TRIM16 in mitigating D-galactose (D-gal)-induced senescent osteoblasts. Initially, we observed diminished bone mineral density (BMD) and impaired bone microstructure in naturally aging (24 months) and D-gal-induced (18 months) aged mice through Dual-energy X-ray absorptiometry (DEXA), micro-CT, hematoxylin and eosin staining, and Masson staining. Immunohistochemistry analysis revealed downregulation of TRIM16 and osteogenic differentiation markers (Collagen-1, Runx-2, osteopontin) in femur samples of aged mice. Furthermore, in D-gal-induced senescent MC3T3-E1 osteoblasts, we observed the suppression of osteogenic differentiation and maturity, along with cytoskeleton impairment via Alkaline phosphatase (ALP), Alizarin Red S, and Rhodamine-phalloidin staining. The protein expression of TRIM16, osteogenic differentiation markers, and antioxidant indicators (Nrf-2, HO-1, SOD1) decreased, while the production of reactive oxygen species (ROS) significantly increased. Knockdown and overexpression of TRIM16 using lentivirus in osteoblasts revealed that the downregulation of TRIM16 inhibited osteogenic differentiation and induced oxidative stress. Notably, TRIM16 overexpression partially attenuated D-gal-induced inhibition of osteogenic differentiation and increased oxidative stress. These findings suggest TRIM16 may mitigate impaired osteogenic differentiation and antioxidant response in D-gal-induced senescent osteoblasts, suggesting its potential as a therapeutic target for SOP.

Multiple applications of metal-organic frameworks (MOFs) in the treatment of orthopedic diseases

Pharmacologic treatment of orthopedic diseases is a common challenge for clinical orthopedic surgeons, and as an important step in the stepwise treatment of orthopedic diseases, it is often difficult to achieve satisfactory results with existing pharmacologic treatments. Therefore, it is increasingly important to find new ways to effectively improve the treatment pattern of orthopedic diseases as well as to enhance the therapeutic efficacy. It has been found that metal-organic frameworks (MOFs) possess the advantages of high specific surface area, high porosity, chemical stability, tunability of structure and biocompatibility. Therefore, MOFs are expected to improve the conventional traditional treatment modality for bone diseases. This manuscript reviewed the applications of MOFs in the treatment of common clinical bone diseases and look forward to its future development.

Krüppel-like factors family in health and disease

Krüppel-like factors (KLFs) are a family of basic transcription factors with three conserved Cys2/His2 zinc finger domains located in their C-terminal regions. It is acknowledged that KLFs exert complicated effects on cell proliferation, differentiation, survival, and responses to stimuli. Dysregulation of KLFs is associated with a range of diseases including cardiovascular disorders, metabolic diseases, autoimmune conditions, cancer, and neurodegenerative diseases. Their multidimensional roles in modulating critical pathways underscore the significance in both physiological and pathological contexts. Recent research also emphasizes their crucial involvement and complex interplay in the skeletal system. Despite the substantial progress in understanding KLFs and their roles in various cellular processes, several research gaps remain. Here, we elucidated the multifaceted capabilities of KLFs on body health and diseases via various compliable signaling pathways. The associations between KLFs and cellular energy metabolism and epigenetic modification during bone reconstruction have also been summarized. This review helps us better understand the coupling effects and their pivotal functions in multiple systems and detailed mechanisms of bone remodeling and develop potential therapeutic strategies for the clinical treatment of pathological diseases by targeting the KLF family.

Clinical utility of the fracture risk assessment tool (FRAX) in biopsy-confirmed coeliac disease

BACKGROUND

People with coeliac disease (CD) are at increased risk of osteoporosis and fractures. Currently, baseline dual-energy X-ray absorptiometry (DXA) is recommended for all patients with newly diagnosed CD. We aimed to determine the prevalence of osteoporosis and the clinical utility of the Fracture Risk Assessment Tool (FRAX) in predicting major osteoporotic fractures (MOF) in patients with biopsy-proven CD.

METHODS

We retrospectively collected data for consecutive adult patients with biopsy-proven CD between 2001 and 2015 who underwent DXA scanning within 1 year of diagnosis and were followed up for a minimum of 7 years. Fracture risk was assessed using FRAX scores, and the incidence of major osteoporotic fractures during the follow-up period was analysed.

RESULTS

A total of 593 patients (median age 45.0 years, 68.5% female) were included. The prevalence of osteopenia and osteoporosis were 32.3% and 14.5%, respectively. Increasing age (OR 1.06, p < .0001), decreasing BMI (OR 0.90, p = .003), and higher baseline immunoglobulin A-tissue tissue transglutaminase titre (OR 1.04, p = .03) were significantly associated with increased risk of osteoporosis. The sensitivity, specificity, positive and negative predictive values of the FRAX tool to predict MOF were 21.2%, 91.3%, 16.3%, 93.5%, respectively. A higher risk of fractures was associated with ongoing gluten exposure (OR 1.86, p = .02), previous fractures (OR 2.69, p = .005), and older age (OR 1.03, p < .0001).

CONCLUSION

Osteoporosis is a common finding in patients with CD. The FRAX tool showed high specificity in predicting osteoporotic fractures and could be used to aid with patient selection for DXA scanning in some cases.

Physical activity attenuates the excess mortality risk from prolonged sitting time among adults with osteoporosis or osteopenia

PURPOSE

Osteoporosis is a common generalized skeletal disorder characterized by compromised bone strength predisposing a person to an increased risk of fracture. This study aims to crystallize associations of physical activity (PA) and sedentary behaviour with the survival of adults with osteoporosis or osteopenia.

METHODS

A total of 3103 participants aged 50 years or older from the National Health and Nutrition Examination Survey (NHANES) were included in the study. All participants were diagnosed with osteopenia or osteoporosis. Multivariable Cox proportional hazards regression models were used to assess the association of PA and sedentary behaviour with overall mortality, cancer-related mortality, and cardiovascular disease (CVD)-related mortality.

RESULTS

During 21349 person-years of follow-up, 675 deaths were documented. Highly active participants had a lower risk of all-cause (hazard ratios [HR] = 0.61; 95% confidence interval [CI], 0.42-0.87; P for trend = 0.004), cancer-specific (HR = 0.64; 95%CI, 0.35-1.17; P for trend = 0.132), CVD-specific (HR = 0.75; 95%CI, 0.45-1.25; P for trend = 0.452), and other (HR, 0.51; 95%CI, 0.29-0.88; P for trend = 0.005) mortality than inactive participants. And sitting time was not associated with mortality among physically active participants; while among those who were insufficiently active or inactive, longer sitting time was associated with increased risks of all-cause (HR per 1-h increase = 1.05; 95% CI, 1.01-1.09), cancer-specific (HR per 1 h increase = 0.98; 95% CI, 0.90-1.07), CVD-specific (HR per 1-h increase = 1.11; 95% CI = 1.04-1.18), and other (HR per 1-h increase = 1.05; 95% CI, 0.98-1.13) mortality in a dose-response manner.

CONCLUSIONS

PA can attenuate the excess mortality risk from prolonged sitting for individuals with osteoporosis and/or osteopenia. The combination of prolonged sedentary behaviour with inactive (participants without any PA during a week) PA was associated with an increased risk of mortality. The all-cause mortality risk of individuals who engage in less than 150 min/wk PA and sit more than 8 h/d is 2.02 (95% CI, 1.37-2.99) times higher than that of individuals who engage in more than 150 min/wk PA and sit less than 4 h/d.

What do we need to address when we treat neglected Monteggia fracture in children

Monteggia fracture is a relatively uncommon injury in pediatric patients, accounting for less than 2% of forearm fractures, characterized by a combination of ulna fracture and radial head dislocation. Neglected Monteggia fractures define as those that have not received treatment within 3 weeks. In children, ulna fractures are easily diagnosed while radial head dislocation may be overlooked, necessitating open reduction after neglecting the Monteggia fracture and potentially causing additional trauma to the child. This study aims to review the pathological characteristics of neglected Monteggia fractures based on the length ratio of the ulna and radius, relative positions between the proximal ends of the ulna and radius, the integrality of annular ligament and the pathological change of proximal radioulnar joint. The findings will provide valuable insights and guidance for managing neglected Monteggia fractures.

Serum Amyloid P Secreted by Bone Marrow Adipocytes Drives Skeletal Amyloidosis

The accumulation of amyloid fibrils has been identified in tissues outside the brain, yet little is understood about the formation of extracerebral amyloidosis and its impact on the aging process of these organs. Here, we demonstrate that both transgenic mice modeling Alzheimer's disease (AD) and naturally aging mice exhibit accumulated senescent bone marrow adipocytes (BMAds), accompanied by amyloid deposits surrounding the BMAds. Senescent BMAds acquire a secretory phenotype, resulting in a marked increase in the secretion of serum amyloid P component (SAP), also known as pentraxin 2 (PTX2). SAP/PTX2 colocalizes with amyloid deposits around senescent BMAds in vivo and is sufficient to promote the formation of insoluble amyloid deposits from soluble Aβ peptides in in vitro and ex vivo 3D BMAd-based culture experiments. Additionally, Combined treatment with SAP/PTX2 and Aβ peptides promotes osteoclastogenesis but inhibits osteoblastogenesis of the precursor cells. Transplantation of senescent BMAds into the bone marrow cavity of healthy young mice is sufficient to induce bone loss. Finally, pharmacological depletion of SAP/PTX2 from aged mice abolishes bone marrow amyloid deposition and effectively rescues the low bone mass phenotype. Thus, senescent BMAds, through the secretion of SAP/PTX2, contribute to the age-associated development of skeletal amyloidosis and resultant bone deficits.

Impact of blade direction on postoperative femoral head varus in PFNA fixed patients: a clinical review and biomechanical research

Intertrochanteric femur fracture is a common type of osteoporotic fracture in elderly patients, and postoperative femoral head varus following proximal femoral nail anti-rotation (PFNA) fixation is a crucial factor contributing to the deterioration of clinical outcomes. The cross-angle between the implant and bone might influence fixation stability. Although there is a wide range of adjustment in the direction of anti-rotation blades within the femoral neck, the impact of this direct variation on the risk of femoral head varus and its biomechanical mechanisms remain unexplored. In this study, we conducted a retrospective analysis of clinical data from 69 patients with PFNA fixation in our institution. We judge the direction of blade on the femoral neck in on the immediate postoperative lateral X-rays or intraoperative C-arm fluoroscopy, investigating its influence on the early postoperative risk of femoral head varus. p < 0.05 indicates significant results in both correlation and regression analyses. Simultaneously, a three-dimensional finite element model was constructed based on the Syn-Bone standard proximal femur outline, exploring the biomechanical mechanisms of the femoral neck-anti-rotation blade direction variation on the risk of this complication. The results indicated that ventral direction insertion of the anti-rotation blade is an independent risk factor for increased femoral head varus. Complementary biomechanical studies further confirmed that ventral angulation leads to loss of fixation stability and a decrease in fixation failure strength. Therefore, based on this study, it is recommended to avoid ventral directional insertion of the anti-rotation blade in PFNA operation or to adjust it in order to reduce the risk of femoral head varus biomechanically, especially in unstable fractures. This adjustment will help enhance clinical outcomes for patients.

Comparison of QCT and DEXA findings for lumbar vertebra in young adults and the elderly

BACKGROUND

The use of dual-energy X-ray absorptiometry (DEXA) and quantitative computed tomography (QCT) methods are important for the diagnosis and follow-up of osteoporosis, and are used especially in cases to determine the degree of osteoporosis and the risk of fracture, monitoring the effectiveness of the treatment applied.

PURPOSE

To compare the parameters measured using the DEXA method from the lumbar (L1-L4) vertebrae and the Hounsfield unit (HU) values measured with QCT at the same levels among young adults and the elderly.

MATERIAL AND METHODS

The study included 155 patients (age range = 26-93 years). A total of 57 (36.8%) patients (age range = 26-64 years) were defined as the first group, and 98 (63.2%) patients (aged ≥65 years) were defined as the second group. T-test and correlation analysis were performed to compare bone mineral density (BMD), T score, and HU values measured using DEXA and QCT.

RESULTS

A statistically significant difference was found between T score, lumbar total BMD, and HU values according to age and sex (P < 0.05). When the values measured from lumbar vertebrae were compared using both DEXA and CT, a high correlation was found between them.

CONCLUSION

In the study, it was observed that QCT attenuation measurements of the lumbar spine measured between different age groups provided reliable results in terms of BMD scanning, as in DEXA. It should be noted that QCT has a longer imaging time and higher radiation dose compared to DEXA, and unnecessary scans should be avoided.

Research progress of the mechanisms and applications of ginsenosides in promoting bone formation

BACKGROUND

Bone deficiency-related diseases caused by various factors have disrupted the normal function of the skeleton and imposed a heavy burden globally, urgently requiring potential new treatments. The multi-faceted role of compounds like ginsenosides and their interaction with the bone microenvironment, particularly osteoblasts can promote bone formation and exhibit anti-inflammatory, vascular remodeling, and antibacterial properties, holding potential value in the treatment of bone deficiency-related diseases and bone tissue engineering.

PURPOSE

This review summarizes the interaction between ginsenosides and osteoblasts and the bone microenvironment in bone formation, including vascular remodeling and immune regulation, as well as their therapeutic potential and toxicity in the broad treatment applications of bone deficiency-related diseases and bone tissue engineering, to provide novel insights and treatment strategies.

METHODS

The literature focusing on the mechanisms and applications of ginsenosides in promoting bone formation before March 2024 was searched in PubMed, Web of Science, Google Scholar, Scopus, and Science Direct databases. Keywords such as "phytochemicals", "ginsenosides", "biomaterials", "bone", "diseases", "bone formation", "microenvironment", "bone tissue engineering", "rheumatoid arthritis", "periodontitis", "osteoarthritis", "osteoporosis", "fracture", "toxicology", "pharmacology", and combinations of these keywords were used.

RESULTS

Ginsenoside monomers regulate signaling pathways such as WNT/β-catenin, FGF, and BMP/TGF-β, stimulating osteoblast generation and differentiation. It exerts angiogenic and anti-inflammatory effects by regulating the bone surrounding microenvironment through signaling such as WNT/β-catenin, NF-κB, MAPK, PI3K/Akt, and Notch. It shows therapeutic effects and biological safety in the treatment of bone deficiency-related diseases, including rheumatoid arthritis, osteoarthritis, periodontitis, osteoporosis, and fractures, and bone tissue engineering by promoting osteogenesis and improving the microenvironment of bone formation.

CONCLUSION

The functions of ginsenosides are diverse and promising in treating bone deficiency-related diseases and bone tissue engineering. Moreover, potential exists in regulating the bone microenvironment, modifying biomaterials, and treating inflammatory-related bone diseases and dental material applications. However, the mechanisms and effects of some ginsenoside monomers are still unclear, and the lack of clinical research limits their clinical application. Further exploration and evaluation of the potential of ginsenosides in these areas are expected to provide more effective methods for treating bone defects.

Interleukin-19 in Bone Marrow Contributes to Bone Loss Via Suppressing Osteogenic Differentiation Potential of BMSCs in Old Mice

BACKGROUND

Cellular senescence is an important process related to the pathogenic mechanism of different disorders, especially bone loss. During senescence, bone marrow stromal cells (BMSCs) lose their self-renewal and functional differentiation abilities. Therefore, finding signals opposing the osteogenic differentiation of BMSCs within bone marrow microenvironment is the important for elucidating these above-mentioned mechanisms. Inflammatory cytokines affect bone physiology and remodeling. However, the function of interleukin-19 (IL-19) in skeletal system remains unclear.

METHODS

The mouse model of IL-19 knockout was established through embryonic stem cell injection for analyzing how IL-19 affected bone formation. Micro-CT examinations were performed to evaluate bone microstructures. We performed a three-point bending test to measure bone stiffness and the ultimate force. Antibody arrays were performed to detect interleukin family members in bone marrow aspirates. BMSCs were cultured and induced for osteogenic differentiation.

RESULTS

According to our findings, there was increased IL-19 accumulation within bone marrow in old mice relative to that in their young counterparts, resulting in bone loss via the inhibition of BMSCs osteogenic differentiation. Among Wnt/β-catenin pathway members, IL-19 strongly upregulated sFRP1 via STAT3 phosphorylation. The inhibition of STAT3 and sFRP1 abolished IL-19's inhibition against the BMSCs osteogenic differentiation.

CONCLUSION

To sum up, IL-19 inhibited BMSCs osteogenic differentiation in old mice. Our findings shed novel lights on pathogenic mechanism underlying age-related bone loss and laid a foundation for further research on identifying novel targets to treat senile osteoporosis.

New evidence on the controversy over the correlation between vertebral osteoporosis and intervertebral disc degeneration: a systematic review of relevant animal studies

OBJECTIVE

The effect of vertebral osteoporosis on disc degeneration remains controversial. The aim of this study was to conduct a systematic review and meta-analysis of relevant animal studies to shed more light on the effects and mechanisms of vertebral osteoporosis on disc degeneration and to promote the resolution of the controversy.

METHODS

The PubMed, Cochrane Library, and Embase databases were searched for studies that met the inclusion criteria. Basic information and data were extracted from the included studies and data were analyzed using STATA 15.1 software. This study was registered on INPLASY with the registration number INPLASY202370099 and https://doi.org/10.37766/inplasy2023.7.0099 .

RESULTS

A total of 13 studies were included in our study. Both animals, rats and mice, were covered. Meta-analysis results showed in disc height index (DHI) (P < 0.001), histological score (P < 0.001), number of osteoblasts in the endplate (P = 0.043), number of osteoclasts in the endplate (P < 0.001), type I collagen (P < 0.001), type II collagen (P < 0.001), aggrecan (P < 0.001), recombinant a disintegrin and metalloproteinase with thrombospondin-4 (ADAMTS-4) (P < 0.001), matrix metalloproteinase-1 (MMP-1) (P < 0.001), MMP-3 (P < 0.001), MMP-13 (P < 0.001), the difference between the osteoporosis group and the control group was statistically significant. In terms of disc volume, the difference between the osteoporosis group and the control group was not statistically significant (P = 0.459).

CONCLUSION

Our study shows that vertebral osteoporosis may exacerbate disc degeneration. Abnormal bone remodeling caused by vertebral osteoporosis disrupts the structural integrity of the endplate, leading to impaired nutrient supply to the disc, increased expression of catabolic factors, and decreased levels of type II collagen and aggrecan may be one of the potential mechanisms.

Targeting SAT1 prevents osteoporosis through promoting osteoclast apoptosis

Osteoporosis is a systemic bone disease characterized by decreased bone mass that is tightly regulated by the coordinated actions of osteoclasts and osteoblasts. Apoptosis as a precise programmed cell death involves a cascade of gene expression events which are mechanistically linked to the regulation of bone metabolism. Nevertheless, the critical biomolecules involved in regulating cell apoptosis in osteoporosis remain unknown. To gain a deeper insight into the relationship between apoptosis and osteoporosis, this study integrated the sequencing results of human samples and using a machine learning workflow to overcome the limitations of a single study. Among all immune cell populations, we assessed the apoptotic level and portrayed the distinct subtypes and lineage differentiation of monocytic cells in osteoporotic tissues. Osteoclasts expressed a higher level of Spermidine/spermine-N1-Acetyltransferase1 (SAT1) during osteoclastogenesis which prevented osteoclasts apoptosis and facilitate osteoporosis progression. In addition, Berenil, one potent SAT1 inhibitor, increased osteoclast apoptosis and reversed the bone loss in the femurs of a murine ovariectomy model. In summary, Berenil promotes osteoclast apoptosis, inhibits the bone resorption and improves the abnormal bone structure in vitro and in vivo models by targeting SAT1, demonstrating its potential as a precise therapeutic strategy for clinical osteoporosis treatment.

A novel index to predict postoperative hypocalcemia in primary hyperparathyroidism

BAKGROUND

Vitamin D (Vit D) deficiency is common in patients with hyperparathyroidism, but the importance of replacement before surgery is controversial. It can be predicted that hypocalcemia risk will be higher in patients with high bone turnover.

AIM

In this study, the effect of preoperative ALP/Vit D ratio on postoperative hypocalcemia was investigated.

METHODS

Among the primary hyperparathyroidism cases who were operated between 2015 and 2022, 158 patients with complete data were included in the study. Preoperative laboratory results, radiological images, and pathology reports of the patients were evaluated retrospectively. The cross-sectional value of the ALP/Vit D value predicting hypocalcemia was calculated. The effect of these parameters on postoperative hypocalcemia was investigated.

RESULTS

The mean age of our patients was 54 (21-81 years). When factors affecting postoperative hypocalcemia were evaluated by univariable analysis, Vit D deficiency and insufficiency (p < 0.001), ALP (p < 0.001), ALP/Vit D ratio (p < 0.001), and T score (p = 0.026) found to be factors affecting postoperative hypocalcemia. In multivariate analysis, the ALP/Vit D ratio was found to be an independent variable in predicting hypocalcemia. It was found that hypocalcemia was 45 times more common in patients with ALP/Vit D > 6.34 (p < 0.001). ALP/Vit D ratio predicts patients who will develop postoperative hypocalcemia with 87.2% sensitivity and 87.1% specificity.

CONCLUSIONS

Vit D deficiency increases the risk of postoperative hypocalcemia, but it is not sufficient alone to predict it. The risk increases more in patients with high bone turnover. The preoperative ALP/Vit D ratio is the strongest predictor of postoperative hypocalcemia risk.

YTHDC1 inhibits osteoclast differentiation to alleviate osteoporosis by enhancing PTPN6 messenger RNA stability in an m6A-hUR-dependent manner

YTHDC1 has been confirmed to mediate osteoporosis (OP) progression by regulating osteogenic differentiation. However, whether YTHDC1 mediates osteoclast differentiation and its molecular mechanism remains unclear. Quantitative real-time polymerase chain reaction and Western blot analysis were performed to detect the levels of YTHDC1, PTPN6, NFATc1, TRAP, RUNX2, alkaline phosphatase, and HUR. YTHDC1 knockout mice was constructed by CRISPR/Cas9 system, and the OP mice model was established by ovariectomy. Hematoxylin and eosin staining and micro-computed tomography were used to evaluate bone formation and bone mass. Mouse primary bone marrow macrophage cells were isolated and induced into osteoclasts. TRAP-positive cells were detected using TRAP staining. MeRIP-qPCR, RIP-qPCR assay, RNA affinity isolation assay, and co-immunoprecipitation assay were used to confirm the interactions among YTHDC1, PTPN6, and HUR. YTHDC1 expression was reduced and positively correlated with lumbar bone mineral density in OP patients. In the ovariectomy model of YTHDC1 knockout mice, bone formation was reduced, bone histomorphology was changed, and osteoclastic-related factor (NFATc1 and TRAP) levels were enhanced. Overexpression YTHDC1 inhibited osteoclast differentiation. YTHDC1 increased PTPN6 messenger RNA stability in an m6A-dependent manner. Moreover, YTHDC1 interacted with HUR to positively regulate PTPN6 expression. PTPN6 knockdown promoted osteoclast differentiation, and this effect was reversed by overexpressing HUR or YTHDC1. YTHDC1 was involved in regulating OP progression through inhibiting osteoclast differentiation by enhancing PTPN6 messenger RNA stability in an m6A-HUR-dependent manner.