The molecular etiology and treatment of glucocorticoid-induced osteoporosis

Combined inhibition of importin-β and PBR enhances osteogenic differentiation of BMSCs by reducing nuclear accumulation of glucocorticoid receptor and promoting its mitochondrial translocation

Excessive buildup of endogenous glucocorticoids has been closely linked to postmenopausal osteoporosis (PMOP), though the underlying mechanisms remain unclear. This study examines the role of glucocorticoid receptor (GR) signaling in PMOP, particularly its translocation to mitochondria, interaction with the peripheral benzodiazepine receptor (PBR), and impact on bone formation. In vitro, primary bone marrow mesenchymal stem cells (BMSCs) from mice were cultured to induce osteogenesis under varying concentrations of dexamethasone. Nuclear GR, mitochondrial GR, and PBR levels were measured, along with the effects of Importazole, an importin-β inhibitor, and Emapunil, a PBR inhibitor, on osteogenic differentiation. In vivo, ovariectomized mice were treated with Importazole and Emapunil to assess their anti-osteoporotic potential. Our results indicate that ovariectomized mice displayed increased nuclear GR, decreased mitochondrial GR, and elevated PBR expression in BMSCs. High dexamethasone impaired osteogenic differentiation, characterized by nuclear GR accumulation, reduced mitochondrial translocation, and increased PBR expression. Co-immunoprecipitation confirmed a direct interaction between mitochondrial GR and PBR. Importazole reduced nuclear GR levels, promoting bone formation and alleviating osteoporosis, while Emapunil enhanced GR mitochondrial translocation, improved mitochondrial function, and strengthened bone health. Combined, Importazole and Emapunil showed superior anti-osteoporotic effects compared to either treatment alone. These findings suggest that estrogen deficiency promotes nuclear GR accumulation and PBR expression in BMSCs, limiting GR mitochondrial translocation and reducing osteogenic differentiation. Combining Importazole and Emapunil could mitigate these effects, offering a promising therapeutic strategy for PMOP.

Foliar spraying with zinc oxide nanoparticles enhances the anti-osteoporotic efficacy of the fruit extracts of Silybum marianum L. by stimulating silybin production

Introduction

Silybum marianum is a medicinal plant that produces silymarin, which has been demonstrated to possess antiviral, anti-neurodegenerative, and anticancer activities. Silybin (A+B) are two major hepatoprotective flavonolignans produced predominantly in S. marianum fruits. Several attempts have been made to increase the synthesis of silymarin, or its primary components, silybin (A+B). Zinc oxide nanoparticles (ZnO-NPs) are considered a highly efficient Zn source widely used to promote crop development and productivity.

Methods

In this study, we aimed to investigate the effects of the foliar application of ZnO-NPs on the growth, yield, photosynthetic pigment content, silybin (A+B) content, and the expression of the chalcone synthase (CHS) gene in S. marianum plants. Different concentrations of ZnO-NPs were administered as foliar sprays to S. marianum plants growing in greenhouse conditions. Furthermore, we evaluated the anti-osteoporotic efficacy of the corresponding fruit extract against dexamethasone (Dex)-induced osteoporosis.

Results and discussion

Foliar treatment at all ZnO-NP concentrations increased the amounts of bioactive components of silybin (A+B), which enhanced the growth and yield of S. marianum plants while increasing the levels of N, P, K, and Zn in their leaves, roots, and fruits; the levels of photosynthetic pigments in their leaves; and silybin (A+B) content in their fruits, thereby increasing the medicinal value of S. marianum. The highest gains were observed in plants sprayed with the highest ZnO-NP concentration (20.0 mg/L). In addition, gene expression studies revealed that ZnO-NPs stimulated silybin (A+B) production by activating CHS genes. The administration of S. marianum extracts to Dex-administered rats increased osteoblast and bone formation while inhibiting osteoclast and bone resorption, thereby protecting the animals against Dex-induced osteoporosis.

PET/CT for the Opportunistic Screening of Osteoporosis and Fractures in Cancer Patients

PURPOSE OF REVIEW

In this review, we outline the different etiologies of osteoporosis in the oncologic setting and describe the basis for using PET/CT as screening tool for osteoporosis with a focus on the radiotracers [18F]FDG and [18F]NaF.

RECENT FINDINGS

Osteoporosis is a condition commonly affecting cancer patients due to their age, cancer-specific treatment agents, and effects of cancer. In terms of the unifying mechanism, decreased ratio of osteoblast-bone formation to osteoclast-bone resorption is responsible for causing osteoporosis. PET/CT, a crucial metabolic imaging modality in the oncologic imaging, could be a useful tool for the opportunistic screening of osteoporosis. There are two approaches with which osteoporosis could be identified with PET/CT-using either the (1) CT- based or (2) PET- based approaches. While the CT-based approach has been used with [18F]FDG PET/CT, both CT- and PET-based approaches can be employed with [18F]NaF-PET/CT as [18F]NaF is a radiotracer specific for osteoblast activity.

Bone complications of cancer treatment

With the advancements in conventional treatment modalities such as radiation, chemotherapy, and surgery, as well as the emergence of immunotherapy, the overall cure rate for solid tumor malignancies has experienced a significant increase. However, it is unfortunate that exposure to cancer treatments can have detrimental effects on the function of osteoblasts and osteoclasts, disturbing bone metabolic homeostasis in patients, as well as causing damage to bone marrow cells and other bone tissues. Consequently, certain tumor treatment options may pose a risk for subsequent bone diseases. Common bone disorders associated with cancer treatment include osteonecrosis, bone loss, and secondary bone tumors. (1)Cancer treatment-related osteonecrosis is primarily linked to the use of radiation therapy and certain chemicals, such as bisphosphonates, denosumab, antiangiogenic agents, and immunomodulators. It has been observed that high-dose radiation therapy is more likely to result in osteonecrosis. (2)Chemicals and hormones, particularly sex hormones, glucocorticoids, and thyroid hormones or thyrotropic hormones, are among the factors that can contribute to cancer treatment-related bone loss. (3)Secondary bone tumors differ from metastases originating from primary tumors, and radiotherapy plays a significant role in their development, while chemotherapy may also exert some influence. Radiogenic secondary bone tumors are predominantly malignant, with osteosarcoma being the most common type. Chemotherapy may be a risk factor for the relatively rare occurrence of secondary Ewing sarcoma of the bone. These treatment-related bone disorders have a considerable adverse impact on the prognosis of cancer patients. Hence, it is imperative to prioritize the bone health of patients undergoing cancer treatment and give it further attention.

Osteoporosis treatment: current drugs and future developments

Osteoporosis is a common systemic metabolic disease characterized by a decrease in bone density and bone mass, destruction of bone tissue microstructure, and increased bone fragility leading to fracture susceptibility. Pharmacological treatment of osteoporosis is the focus of current research, and anti-osteoporosis drugs usually play a role in inhibiting bone resorption, promoting bone formation, and having a dual role. However, most of the drugs have the disadvantages of single target and high toxic and side effects. There are many types of traditional Chinese medicines (TCM), from a wide range of sources and mostly plants. Herbal plants have unique advantages in regulating the relationship between osteoporosis and the immune system, acupuncture therapy has significant therapeutic effects in combination with medicine for osteoporosis. The target cells and specific molecular mechanisms of TCM in preventing and treating osteoporosis have not been fully elucidated. At present, there is a lack of comprehensive understanding of the pathological mechanism of the disease. Therefore, a better understanding of the pathological signaling pathways and key molecules involved in the pathogenesis of osteoporosis is crucial for the design of therapeutic targets and drug development. In this paper, we review the development and current status of anti-osteoporosis drugs currently in clinical application and under development to provide relevant basis and reference for drug prevention and treatment of osteoporosis, with the aim of promoting pharmacological research and new drug development.

Lumbar vertebral bone density is decreased in horses with pituitary pars intermedia dysfunction

BACKGROUND

Pathological fractures have been reported in equids with pituitary pars intermedia dysfunction (PPID) but their prevalence and pathogenesis is unknown.

OBJECTIVES

To compare: (1) bone mineral density (BMD) in weight bearing and nonweight bearing bones in PPID+ equids and aged and young PPID- controls; and (2) biomechanical properties of the fourth lumbar vertebral body in PPID+ equids and aged PPID- equids.

STUDY DESIGN

Case-control study: five PPID+ equids and six aged and four young PPID- control horses.

METHODS

PPID status was based on clinical signs and necropsy examination of the pituitary gland (PG). The lumbar vertebral column, right front third metacarpus (MC3), left hind third metatarsus (MT3), and PG were removed after euthanasia. BMD was determined by quantitative computed tomography of regions of interest (ROI) in each bone and biomechanical testing was performed on the fourth lumbar vertebral body. Serum concentrations of parathormone (PTH), ionised Ca++ , 25-hydroxyvitamin D, and osteocalcin (OC) were also measured. Data were analysed using one-way ANOVA and correlation analyses.

RESULTS

BMD of trabecular and cortical regions of interest (ROI) of the third, fourth (L4), and fifth lumbar vertebrae were significantly lower in PPID+ equids as compared with aged (p < 0. 001) and young (p < 0.01) PPID- controls. In contrast, no differences were found in BMD of trabecular or cortical ROIs of MC3 and MT3 between groups. No differences were detected in force at fracture, displacement at fracture, Young's modulus or strain of L4 between PPID+ and aged PPID- horses. No differences were found in serum PTH, ionised Ca++ , 25-hydroxyvitamin D, or OC concentrations between groups.

MAIN LIMITATIONS

Limited number of equids studied and variation in test results.

CONCLUSIONS

BMD of nonweight bearing bones can be decreased with PPID and could increase risk of developing pathological fractures.

Metabolomics analysis of the potential mechanism of Yi-Guan-Jian decoction to reverse bone loss in glucocorticoid-induced osteoporosis

BACKGROUND

Glucocorticoid-induced osteoporosis (GIOP) is a disease in which long-term use of glucocorticoid causes bone loss, deterioration of bone microstructure and fracture. Currently, clinical drugs targeting this disease have certain side effects. There is still a need to find effective drugs with fewer side effects. The theory of traditional Chinese medicine suggests that YGJ has therapeutic effect on GIOP, but it has not been explained. Therefore, this study aims to explore the protective effect of YGJ on GIOP mouse models and elucidate the underlying mechanism through LC-MS-based metabolomics analysis.

METHODS

The general condition of 8 week age male C57BL/6J mice was recorded after 8 weeks of treatment with dexamethasone (DEX) and YGJ. Bone-related parameters and bone morphology were determined by Micro-CT. HE staining was used to observe the pathological changes of bone tissue. Serum levels of bone metabolism markers were detected by ELISA. Liver metabolomics analysis was conducted to search for the significant markers of anti-GIOP of YGJ and the metabolic pathway affecting it.

RESULTS

After treatment, YGJ significantly reversed the weight loss caused by DEX; increase the number of bone trabecular in ROI region, significantly improve the bone-related parameters of GIOP mice, and increase the levels of alkaline phosphatase and osteocalcin. In the study of metabolic mechanism, YGJ reversed 24 potential markers in GIOP mice. These included cortisol, 3-hydroxybutyric acid, taurine, esculin and uric acid, which are closely associated with osteoporosis. Topological analysis results showed that YGJ had the most significant effect on taurine and hypotaurine metabolism, with - log10 (P) > 2.0 and Impact > 0.4.

CONCLUSIONS

Yi-Guan-Jian decoction can increase bone density and improve bone microstructure by regulating the levels of alkaline phosphatase and osteocalcin and reverse bone loss in GIOP mouse model. The underlying metabolic mechanism may be related to taurine and hypotaurine metabolic pathway.

Diosmin mitigates dexamethasone-induced osteoporosis in vivo: Role of Runx2, RANKL/OPG, and oxidative stress

Secondary osteoporosis is commonly caused by long-term intake of glucocorticoids (GCs), such as dexamethasone (DEX). Diosmin, a natural substance with potent antioxidant and anti-inflammatory properties, is clinically used for treating some vascular disorders. The current work targeted exploring the protective properties of diosmin to counteract DEX-induced osteoporosis in vivo. Rats were administered DEX (7 mg/kg) once weekly for 5 weeks, and in the second week, vehicle or diosmin (50 or 100 mg/kg/day) for the next four weeks. Femur bone tissues were collected and processed for histological and biochemical examinations. The study findings showed that diosmin alleviated the histological bone impairments caused by DEX. In addition, diosmin upregulated the expression of Runt-related transcription factor 2 (Runx2) and phosphorylated protein kinase B (p-AKT) and the mRNA transcripts of Wingless (Wnt) and osteocalcin. Furthermore, diosmin counteracted the rise in the mRNA levels of receptor activator of nuclear factor-kB ligand (RANKL) and the reduction in osteoprotegerin (OPG), both were induced by DEX. Diosmin restored the oxidant/antioxidant equilibrium and exerted significant antiapoptotic activity. The aforementioned effects were more pronounced at the dose level of 100 mg/kg. Collectively, diosmin has proven to protect rats against DEX-induced osteoporosis by augmenting osteoblast and bone development while hindering osteoclast and bone resorption. Our findings could be used as a stand for recommending supplementation of diosmin for patients chronically using GCs.

Carbonic Anhydrase II Activators in Osteopetrosis Treatment: A Review

Osteopetrosis is a rare hereditary illness generated by failure in osteoclasts resulting in elevated bone densities. Patients with osteopetrosis possess several complications, like dental caries, earlier teeth loss, delayed eruption, malformed crowns and roots, and lamina dura thickening. Since deficiency of carbonic anhydrase II is a major cause behind osteopetrosis, carbonic anhydrase II activators have a large number of applications in osteopetrosis treatment. There is a lack of a comprehensive review on osteopetrosis, pathogenesis of dental abnormalities, and the role of carbonic anhydrase II activators in osteopetrosis treatment. To address this research gap, the authros perfomed a comprehensive review on osteopetrosis and its types, pathogenesis of dental abnormalities, and the role of carbonic anhydrase II activators in osteopetrosis treatment. A brief introduction to the pathogenesis of dental abnormalities and regeneration is provided in this survey. A discussion of types of osteopetrosis depending on genetic inheritance, such as autosomal dominant, autosomal recessive, and X-linked inheritance osteopetrosis, is presented in this survey. The paper also focuses on the importance of carbonic anhydrase II activators as a potential drug therapy for dental osteopetrosis. In addition, a brief note on the role of azole and fluconazole in treating osteopetrosis is given. Finally, future directions involving gene therapy for dental osteopetrosis are described.

ED-71 Prevents Glucocorticoid-Induced Osteoporosis by Regulating Osteoblast Differentiation via Notch and Wnt/β-Catenin Pathways

PURPOSE

Long-term glucocorticoid- usage can lead to glucocorticoid-induced osteoporosis (GIOP). The study focused on the preventative effects of a novel active vitamin D3 analog, eldecalcitol (ED-71), against GIOP and explored the underlying molecular mechanisms.

METHODS

Intraperitoneal injection of methylprednisolone (MPED) or dexamethasone (DEX) induced the GIOP model within C57BL/6 mice in vivo. Simultaneously, ED-71 was orally supplemented. Bone histological alterations, microstructure parameters, novel bone formation rates, and osteogenic factor changes were evaluated by hematoxylin-eosin (HE) staining, micro-computed tomography, calcein/tetracycline labeling, and immunohistochemical (IHC) staining. The osteogenic differentiation level and mineralization in pre-osteoblast MC3T3-E1 cells were evaluated in vitro using alkaline phosphatase (ALP) staining, alizarin red (AR) staining, quantitative polymerase chain reaction (qPCR), Western blotting, and immunofluorescence staining.

RESULTS

ED-71 partially prevented bone mass reduction and microstructure parameter alterations among GIOP-induced mice. Moreover, ED-71 also promoted new bone formation and osteoblast activity while inhibiting osteoclasts. In vitro, ED-71 promoted osteogenic differentiation and mineralization in DEX-treated MC3T3-E1 cells and boosted the levels of osteogenic-related factors. Additionally, GSK3-β and β-catenin expression levels were elevated after ED-71 was added to cells and were accompanied by reduced Notch expression. The Wnt signaling inhibitor XAV939 and Notch overexpression reversed the ED-71 promotional effects toward osteogenic differentiation and mineralization.

CONCLUSION

ED-71 prevented GIOP by enhancing osteogenic differentiation through Notch and Wnt/GSK-3β/β-catenin signaling. The results provide a novel translational direction for the clinical application of ED-71 against GIOP.

Gu Sui Bu (Drynaria fortunei J. Sm.) antagonizes glucocorticoid-induced mineralization reduction in zebrafish larvae by modulating the activity of osteoblasts and osteoclasts

ETHNOPHARMACOLOGICAL RELEVANCE

Gu Sui Bu (GSB), the dried rhizome of Drynaria fortunei J. Sm., is widely used in traditional Chinese medicine for treating fractures and osteoporosis. Although glucocorticoids are widely prescribed in modern medicine, the efficacy of GSB in treating glucocorticoid-induced osteoporosis (GIOP) remains unclear.

AIM OF THE STUDY

GIOP is one of the most prevalent forms of osteoporosis and increases the risk of fracture, which can cause severe complications in elderly people. Safe, efficacious, and cost-effective treatment options for GIOP are thus warranted. The present study investigated the efficacy and mechanism of GSB for treating GIOP.

MATERIALS AND METHODS

We established an efficient and robust in vivo GIOP model by optimizing zebrafish larvae rearing conditions and the dose and duration of dexamethasone treatment. Bone calcification was evaluated through calcein staining. To quantify the degree of vertebral mineralization in the larvae, we developed a scoring system based on the rate of vertebral calcification; this system reduced quantification errors among individual zebrafish caused by inconsistencies in staining or imaging parameters. Quantitative real-time polymerase chain reaction was used to access the expression levels of genes essential to the differentiation and function of bone cells. High-performance liquid chromatography was employed to identify naringin in the GSB extract.

RESULTS

GSB significantly reversed the dexamethasone-induced calcification delay in zebrafish larvae. GSB enhanced osteoblast activity by increasing the expression of collagen I, osteopontin, and osteonectin and repressed bone resorption by decreasing the expression of matrix metalloproteinases (mmps), including mmp9 and mmp13a. We also identified naringin as one of the constituents of GSB responsible for the herbal extract's anti-GIOP activity.

CONCLUSIONS

Using the in vivo zebrafish GIOP model that we established, the efficacy of traditional Chinese medicines in treating GIOP could be systematically investigated. GSB has an osteogenic effect and may thus be an efficacious and cost-effective treatment option for GIOP. Notably, bone resorption activity was found to be retained after GSB treatment, which would be beneficial for maintaining normal bone remodeling.

Risk for osteoporosis and fracture with glucocorticoids

Glucocorticoid use is ubiquitous and is associated with multiple adverse reactions. Among them, osteoporosis and bone fractures are of our concern. In this review, we present current evidence on the effect of glucocorticoids on bone mineral density and the risk of fractures, the mechanisms underlying those effects, and the recommendations for monitoring and treating patients who take them. The bone mineral density of the lumbar spine and total hip is lower, and the risk of fractures is higher in glucocorticoid users than non-users. These effects have a rapid onset, are dose-dependent, and improve soon after discontinuation of glucocorticoids. They also appear to occur even with non-systemic routes of administration and with low doses. Glucocorticoids reduce bone mineral density by increasing osteoclast activity and decreasing osteoblast and osteocyte activity. Calcium metabolism and parathyroid hormone activity are less important than was initially thought. Treatment decisions are on risk stratification using clinical, radiographic, and prediction tools. Our armamentarium for the treatment and prevention of glucocorticoid-induced osteoporosis includes calcium and vitamin D, bisphosphonates, recombinant parathyroid hormone, monoclonal antibodies against receptor activator of nuclear factor kappa-B ligand, and hormone treatments.

Osteoporosis in Patients With Respiratory Diseases

Climate change, environmental pollution, and virus epidemics have sharply increased the number of patients suffering from respiratory diseases in recent years. Prolonged periods of illness and drug use increase the occurrence of complications in these patients. Osteoporosis is the common bone metabolism disease with respiratory disturbance, which affects prognosis and increases mortality of patients. The problem of osteoporosis in patients with respiratory diseases needs more attention. In this review, we concluded the characteristics of osteoporosis in some respiratory diseases including COPD, asthma, COVID-19, tuberculosis, and lung cancer. We revealed that hypoxia was the common pathogenesis of osteoporosis secondary to respiratory diseases, with malnutrition and corticosteroid abuse driving the progression of osteoporosis. Hypoxia-induced ROS accumulation and activated HIF-1α lead to attenuated osteogenesis and enhanced osteoclastogenesis in patients with respiratory diseases. Tuberculosis and cancer also invaded bone tissue and reduced bone strength by direct infiltration. For the treatment of osteoporosis in respiratory patients, oral-optimized bisphosphonates were the best treatment modality. Vitamin D was a necessary supplement, both for calcium absorption in osteogenesis and for improvement of respiratory lesions. Reasonable adjustment of the dose and course of corticosteroids according to the etiology and condition of patients is beneficial to prevent the occurrence and development of osteoporosis. Additionally, HIF-1α was a potential target for the treatment of osteoporosis in respiratory patients, which could be activated under hypoxia condition and involved in the process of bone remodeling.

Geniposide ameliorated dexamethasone-induced endoplasmic reticulum stress and mitochondrial apoptosis in osteoblasts

ETHNOPHARMACOLOGICAL RELEVANCE

Eucommia ulmoides Oliver has been traditionally used for treatment of various diseases, including osteoporosis, knee pain, and paralysis. The extract of Eucommia ulmoides has been reported to stimulate the bone formation and suppress the bone resorption, leading to protection against osteoporosis (OP). Geniposide (GEN) has been considered as one of the effective compounds responsible for the therapeutic efficacy of Eucommia ulmoides against OP.

AIM OF THE STUDY

To explore whether GEN protected against dexamethasone (DEX)-induced osteoporosis (OP) by activating NRF2 expression and inhibiting endoplasmic reticulum (ER) stress.

MATERIALS AND METHODS

The DEX-induced rat OP models were duplicated. The pathological changes were examined by histological/immunohistochemical evaluation and micro-computed tomography (micro-CT) assessment. Apoptosis was detected by a flow cytometer. Mitochondrial Ca²⁺ concentrations and mitochondrial membrane potential were detected. Western blot assays were used to detect the protein expression.

RESULTS

GEN effectively reversed DEX-induced pathological changes of trabecular bone in rats. In addition, the DEX-increased expression of ATF4/CHOP was also ameliorated. In MC3T3-E1 cells, DEX promoted endoplasmic reticulum (ER) stress and mitochondrial apoptosis. Inhibition of ER stress abolished the induction of apoptosis by DEX. Similarly, GEN significantly ameliorated DEX-induced mitochondrial apoptosis. The possible underlying mechanism might be associated with the pharmacological effects of GEN on activating the expression of NRF2 and alleviating ER stress in DEX-treated MC3T3-E1 cells.

CONCLUSION

GEN ameliorated DEX-induced ER stress and mitochondrial apoptosis in osteoblasts.

The effect of Rutin hydrate on Glucocorticoids induced osteoporosis in mandibular alveolar bone in Albino rats (Radiological, histological and histochemical study)

Background

Glucocorticoids are used in different conditions such as autoimmune disorders and organ transplantation and their administration is the most common cause of secondary osteoporosis. Rutin is a flavonoid found in many plants. Flavonoids are natural products with various therapeutic and biological effects.

Objective

Is to investigate the effect of Rutin Hydrate as a form of Rutin on glucocorticoid induced osteoporosis in mandibular alveolar bone radiologically, histologically and histochemically.

Methods

Twenty-one adult male Albino rats were randomly divided into three groups. Group I (control), group II (osteoporotic) and group III (Rutin Hydrate treated). In both group II and III rats received 21 mg/kg of methylprednisolone daily for four weeks. Then group III received 50 mg/kg of rutin hydrate in distilled water daily for another four weeks. At the end of the experiment, mandibles were dissected for radiographic assessment, then processed for histological and histochemical examination and statistical analysis.

Results

Radiologically, administration of Rutin Hydrate was able to enhance bone density than osteoporotic group. Histological examination revealed preserved cortical bone thickness that had been statistically proved. Apparently normal sized marrow cavities, some plump osteoblasts and normal osteocytes were seen in group III. Histochemical examination showed statistical increase in the area percentage of newly formed collagen in group III than group II.

Conclusions

Rutin Hydrate was able to modify the radiological and histological picture of osteoporotic alveolar bone. This was achieved by the ability of Rutin Hydrate to increase bone density, preserve cortical plates thickness and enhance new collagen formation that was proved histochemically.

A bibliometric and visualization analysis of glucocorticoid-induced osteoporosis research from 2012 to 2021

INTRODUCTION

Glucocorticoid-induced osteoporosis (GIOP) is the most common cause of secondary osteoporosis. Although many studies related to GIOP have been published, there was no bibliometric analysis in this field. This study aimed to investigate the research trends on GIOP by using bibliometric analysis.

MATERIALS AND METHODS

All data were collected from the Web of Science Core Collection (WoSCC). All original research articles regarding GIOP from 2012 to 2021 were retrieved. CiteSpace was used to analyze the distribution of countries, institutions, journals, authors, and keywords. We revealed hotspots and trends in the field by drawing co-occurrence keyword maps and identifying burst keywords.

RESULTS

From 2012 to 2021, 685 relevant articles were published, with a peak in 2018 in the annual number of publications. China and McMaster University were the leading country and institution in this field with 208 and 12 publications, respectively. Osteoporosis International was the journal with the most studies, while Journal of Bone and Mineral Research was the most cited journal. "Bone mineral density", "fracture", "postmenopausal women", "prevention" and "therapy" were the most high-frequency keywords, while "bone mineral density", "bisphosphonate" and "metabolism" were the top high-centrality keywords.

CONCLUSION

The results from this bibliometric study provided insight into the status and research trends in GIOP of the past decade, which could help researchers quickly determine the current hotspots and frontier trends in this field.

Expression of Renal Vitamin D and Phosphatonin-Related Genes in a Sheep Model of Osteoporosis

Simple Summary

Osteoporosis is a significant public health issue around the world, with post-menopausal osteoporosis due to estrogen deficiency resulting in approximately ¾ of cases. Treatment with glucocorticoids is another common cause of osteoporosis in humans. Sheep are a well-established model for osteoporosis in humans. In this study, aged sheep had their ovaries removed (ovariectomy) to simulate estrogen deficiency, and some sheep were also treated with glucocorticoids. The results showed that expression of the gene klotho in the kidney had the most marked difference in ovariectomized sheep treated with glucocorticoids for 2 months followed by a recovery period of 3 months. Klotho is known as the “anti-aging” hormone and is an important regulator of calcium and phosphorus metabolism. It may therefore be involved in the recovery of bone mineral density seen in ovariectomized sheep treated with glucocorticoids for 2 months followed by euthanasia at 5 months. As such, it could be an important treatment target for osteoporosis in humans.

Abstract

Osteoporosis is a significant public health issue around the world, with post-menopausal osteoporosis due to estrogen deficiency resulting in approximately ¾ of cases. In this study, 18 aged Merino ewes were ovariectomized, and 10 were controls. Three of the ovariectomized ewes were treated weekly with 400 mg of methylprednisolone for 5 months and three were treated weekly for 2 months, followed by a 3-month recovery period. At 2 months, five control animals and six ovariectomized animals were euthanized. At 5 months, all the remaining ewes were euthanized. Kidney samples were collected postmortem for qPCR analysis of NPT1, PTH1R, NPT2a, NPT2c, Klotho, FGFR1IIIc, VDR, CYP24A1, CYP27B1, TRPV5, TRPV6, CalD9k, CalD28k, PMCA and NCX1. Ovariectomized sheep had significantly greater VDR expression compared with other groups. Ovariectomized sheep treated with glucocorticoids for 2 months followed by euthanasia at 5 months showed significant differences in TRPV5, CYP24A1 and klotho gene expression compared to other groups. Differences in klotho expression were most marked after adjustment for repeated measures (p = 0.1). Klotho is known as the “anti-aging” hormone and is involved in calcium and phosphorus metabolism. Klotho may be involved in the recovery of bone mineral density in ovariectomized sheep treated with glucocorticoids for 2 months followed by euthanasia at 5 months. Further research on the role of klotho is recommended.

Geniposide Ameliorated Dexamethasone-Induced Cholesterol Accumulation in Osteoblasts by Mediating the GLP-1R/ABCA1 Axis

Background: Overexposure to glucocorticoid (GC) produces various clinical complications, including osteoporosis (OP), dyslipidemia, and hypercholesterolemia. Geniposide (GEN) is a natural iridoid compound isolated from Eucommia ulmoides. Our previous study found that GEN could alleviate dexamethasone (DEX)-induced differentiation inhibition of MC3T3-E1 cells. However, whether GEN protected against Dex-induced cholesterol accumulation in osteoblasts was still unclear. Methods: DEX was used to induce rat OP. Micro-CT data was obtained. The ALP activity and mineralization were determined by the staining assays, and the total intracellular cholesterol was determined by the ELISA kits. The protein expression was detected by western blot. Results: GEN ameliorated Dex-induced micro-structure damages and cell differentiation inhibition in the bone trabecula in rats. In MC3T3-E1 cells, Dex enhanced the total intracellular cholesterol, which reduced the activity of cell proliferation and differentiation. Effectively, GEN decreased DEX-induced cholesterol accumulation, enhanced cell differentiation, and upregulated the expression of the GLP-1R/ABCA1 axis. In addition, inhibition of ABAC1 expression reversed the actions of GEN. Treatment with Exendin9-39, a GLP-1R inhibitor, could abrogate the protective activity of GEN. Conclusions: GEN ameliorated Dex-induced accumulation of cholesterol and inhibition of cell differentiation by mediating the GLP-1R/ABCA1 axis in MC3T3-E1 cells.

Dexamethasone Suppresses Palatal Cell Proliferation through miR-130a-3p

Cleft lip with or without cleft palate (CL/P) is one of the most common congenital birth defects. This study aims to identify novel pathogenic microRNAs associated with cleft palate (CP). Through data analyses of miRNA-sequencing for developing palatal shelves of C57BL/6J mice, we found that miR-449a-3p, miR-449a-5p, miR-449b, miR-449c-3p, and miR-449c-5p were significantly upregulated, and that miR-19a-3p, miR-130a-3p, miR-301a-3p, and miR-486b-5p were significantly downregulated, at embryonic day E14.5 compared to E13.5. Among them, overexpression of the miR-449 family (miR-449a-3p, miR-449a-5p, miR-449b, miR-449c-3p, and miR-449c-5p) and miR-486b-5p resulted in reduced cell proliferation in primary mouse embryonic palatal mesenchymal (MEPM) cells and mouse cranial neural crest cell line O9-1. On the other hand, inhibitors of miR-130a-3p and miR-301a-3p significantly reduced cell proliferation in MEPM and O9-1 cells. Notably, we found that treatment with dexamethasone, a glucocorticoid known to induce CP in mice, suppressed miR-130a-3p expression in both MEPM and O9-1 cells. Moreover, a miR-130a-3p mimic could ameliorate the cell proliferation defect induced by dexamethasone through normalization of Slc24a2 expression. Taken together, our results suggest that miR-130-3p plays a crucial role in dexamethasone-induced CP in mice.