Exploration of the miR-187-3p/CNR2 pathway in modulating osteoblast differentiation and treating postmenopausal osteoporosis through mechanical stress.

This study aimed to explore how mechanical stress affects osteogenic differentiation via the miR-187-3p/CNR2 pathway. To conduct this study, 24 female C57BL/6 mice, aged 8 weeks, were used and divided into four groups. The Sham and OVX groups did not undergo treadmill exercise, while the Sham + EX and OVX + EX groups received a 8-week treadmill exercise. Post-training, bone marrow and fresh femur samples were collected for further analysis. Molecular biology analysis, histomorphology analysis, and micro-CT analysis were conducted on these samples. Moreover, primary osteoblasts were cultured under osteogenic conditions and divided into GM group and CTS group. The cells in the CTS group underwent a sinusoidal stretching regimen for either 3 or 7 days. The expression of early osteoblast markers (Runx2, OPN, and ALP) was measured to assess differentiation. The study findings revealed that mechanical stress has a regulatory impact on osteoblast differentiation. The expression of miR-187-3p was observed to decrease, facilitating osteogenic differentiation, while the expression of CNR2 increased significantly. These observations suggest that mechanical stress, miR-187-3p, and CNR2 play crucial roles in regulating osteogenic differentiation. Both in vivo and in vitro experiments have confirmed that mechanical stress downregulates miR-187-3p and upregulates CNR2, which leads to the restoration of distal femoral bone mass and enhancement of osteoblast differentiation. Therefore, mechanical stress promotes osteoblasts, resulting in improved osteoporosis through the miR-187-3p/CNR2 signaling pathway. These findings have broad prospect and provide molecular biology guidance for the basic research and clinical application of exercise in the prevention and treatment of PMOP.

Gut-bone axis research: unveiling the impact of gut microbiota on postmenopausal osteoporosis and osteoclasts through Mendelian randomization.

Background: Postmenopausal osteoporosis is a prevalent disease that affects the bone health of middle-aged and elderly women. The link between gut microbiota and bone health, known as the gut-bone axis, has garnered widespread attention. Methods: We employed a two-sample Mendelian randomization approach to assess the associations between gut microbiota with osteoclasts and postmenopausal osteoporosis, respectively. Single nucleotide polymorphisms associated with the composition of gut microbiota were used as instrumental variables. By analyzing large-scale multi-ethnic GWAS data from the international MiBioGen consortium, and combining data from the eQTLGen consortium and the GEFOS consortium, we identified microbiota related to osteoclasts and postmenopausal osteoporosis. Key genes were further identified through MAGMA analysis, and validation was performed using single-cell data GSE147287. Results: The outcomes of this study have uncovered significant associations within the gut microbiome community, particularly with the Burkholderiales order, which correlates with both an increase in osteoclasts and a reduced risk of postmenopausal osteoporosis. with an odds ratio (OR) of 0.400, and a P-value of 0.011. Further analysis using single-cell data allowed us to identify two key genes, FMNL2 and SRBD1, that are closely linked to both osteoclasts and osteoporosis. Conclusion: This study utilizing Mendelian randomization and single-cell data analysis, provides new evidence of a causal relationship between gut microbiota and osteoclasts, as well as postmenopausal osteoporosis. It was discovered that the specific microbial group, the Burkholderiales order, significantly impacts both osteoporosis and osteoclasts. Additionally, key genes FMNL2 and SRBD1 were identified, offering new therapeutic strategies for the treatment of postmenopausal osteoporosis.

lncTIMP3 promotes osteogenic differentiation of bone marrow mesenchymal stem cells via miR-214/Smad4 axis to relieve postmenopausal osteoporosis.

BACKGROUND: Promoting the balance between bone formation and bone resorption is the main therapeutic goal for postmenopausal osteoporosis (PMOP), and bone marrow mesenchymal stem cells (BMSCs) osteogenic differentiation plays an important regulatory role in this process. Recently, several long non-coding RNAs (lncRNAs) have been reported to play an important regulatory role in the occurrence and development of OP and participates in a variety of physiological and pathological processes. However, the role of lncRNA tissue inhibitor of metalloproteinases 3 (lncTIMP3) remains to be investigated. METHODS: The characteristics of BMSCs isolated from the PMOP rat model were verified by flow cytometry assay, alkaline phosphatase (ALP), alizarin red and Oil Red O staining assays. Micro-CT and HE staining assays were performed to examine histological changes of the vertebral trabeculae of the rats. RT-qPCR and western blotting assays were carried out to measure the RNA and protein expression levels. The subcellular location of lncTIMP3 was analyzed by FISH assay. The targeting relationships were verified by luciferase reporter assay and RNA pull-down assay. RESULTS: The trabecular spacing was increased in the PMOP rats, while ALP activity and the expression levels of Runx2, Col1a1 and Ocn were all markedly decreased. Among the RNA sequencing results of the clinical samples, lncTIMP3 was the most downregulated differentially expressed lncRNA, also its level was significantly reduced in the OVX rats. Knockdown of lncTIMP3 inhibited osteogenesis of BMSCs, whereas overexpression of lncTIMP3 exhibited the reverse results. Subsequently, lncTIMP3 was confirmed to be located in the cytoplasm of BMSCs, implying its potential as a competing endogenous RNA for miRNAs. Finally, the negative targeting correlations of miR-214 between lncTIMP3 and Smad4 were elucidated in vitro. CONCLUSION: lncTIMP3 may delay the progress of PMOP by promoting the activity of BMSC, the level of osteogenic differentiation marker gene and the formation of calcium nodules by acting on the miR-214/Smad4 axis. This finding may offer valuable insights into the possible management of PMOP.

Exploring the multicomponent synergy mechanism of Zuogui Wan on postmenopausal osteoporosis by a systems pharmacology strategy.

OBJECTIVE: To explore the multi-component synergistic mechanism of Zuogui Wan (, ZGW) in treating postmenopausal osteoporosis (PMOP). METHODS: The main components and target genes of ZGW were screened via the Traditional Chinese Medicine Systems Pharmacology (TCMSP). In addition, the target gene sets of PMOP were derived from the GeneCards and Online Mendelian Inheritance in Man databases. The search tool for recurring instances of neighbouring genes (STRING) 11.0 software was used to analyze the interaction among intersecting genes. Cytoscape 3.6.1 software and the Matthews correlation coefficient (MCC) algorithm were used to screen the core genes. Fifty Sprague-Dawley female rats were randomly divided into the sham-operated (Sham) group and the four ovariectomized (OVX) subgroups. Rats subjected to Sham or OVX were administered with the vehicle (OVX, 1 mL water/100 g weight), 17ß-estradiol (E2, 50 µg·kg-1·d-1), and lyophilized powder of ZGW at a low dose of 2.3 (ZGW-L) and high dose of 4.6 (ZGW-H) g·kg-1·d-1 for three months. The bone density and bone strength were assessed using dual-energy X-ray and three-point bending tests, respectively. Furthermore, enzyme-linked immun-osorbent assay, Hematoxylin-eosin staining, and western blot analysis were used to determine the potential pharmacological mechanisms of action of ZGW in PMOP. RESULTS: A total of 117 active compounds of ZGW were screened from the TCMSP. Furthermore, 108 intersecting genes of drugs and diseases were identified. Using STRING software and the MCC algorithm, ten core genes, including C-X-C chemokine living 8 (CXCL8), C-C chemokine receptor type 2 (CCR2), alpha-2a active receptor (ADRA2A), melatonin receptor type 1B (MTNR1B), and amyloid-beta A4 protein (APP), were identified. The anti-osteoporosis regulation network of ZGW was constructed using the Cytoscape software. The animal experiments demonstrated that ZGW groups significantly reduced the serum levels of ß-C-terminal telopeptide of type I collagen (ß-CTX) and increased serum levels of bone-specific alkaline phosphatase (BALP) (P < 0.05, P < 0.01). The OVX group exhibited a significant decrease in bone mineral density and bone strength compared with the Sham group (P < 0.01). Moreover, treatment with ZGW resulted in increased trabecular thickness, improved arrangement of trabecular structure, and reduced empty bone lacunae. Furthermore, treatment with ZGW significantly increased the protein expression of CXCL8, ADRA2A, and CCR2 (P < 0.05, P < 0.01), and significantly decreased the protein expression of Runx2 (P < 0.01). Furthermore, the ZGW and E2 groups demonstrated significantly increased BMD (P < 0.05, P < 0.01), improved bone strength (P < 0.05, P < 0.01), reduced expression of CXCL8, ADRA2A, and CCR2, and increased runt-related transcription factor 2 levels in bone tissue (P < 0.05, P < 0.01) compared with the OVX group. However, there were no significant differences in MTNR1B and APP expression among the groups. CONCLUSION: ZGW shows synergistic mechanisms in PMOP through multiple components, targets, and pathways.

Analysis and validation of biomarkers of immune cell-related genes in postmenopausal osteoporosis: An observational study.

Postmenopausal osteoporosis (PMOP) is a common metabolic inflammatory disease. In conditions of estrogen deficiency, chronic activation of the immune system leads to a hypo-inflammatory phenotype and alterations in its cytokine and immune cell profile, although immune cells play an important role in the pathology of osteoporosis, studies on this have been rare. Therefore, it is important to investigate the role of immune cell-related genes in PMOP. PMOP-related datasets were downloaded from the Gene Expression Omnibus database. Immune cells scores between high bone mineral density (BMD) and low BMD samples were assessed based on the single sample gene set enrichment analysis method. Subsequently, weighted gene co-expression network analysis was performed to identify modules highly associated with immune cells and obtain module genes. Differential analysis between high BMD and low BMD was also performed to obtain differentially expressed genes. Module genes are intersected with differentially expressed genes to obtain candidate genes, and functional enrichment analysis was performed. Machine learning methods were used to filter out the signature genes. The receiver operating characteristic (ROC) curves of the signature genes and the nomogram were plotted to determine whether the signature genes can be used as a molecular marker. Gene set enrichment analysis was also performed to explore the potential mechanism of the signature genes. Finally, RNA expression of signature genes was validated in blood samples from PMOP patients and normal control by real-time quantitative polymerase chain reaction. Our study of PMOP patients identified differences in immune cells (activated dendritic cell, CD56 bright natural killer cell, Central memory CD4 T cell, Effector memory CD4 T cell, Mast cell, Natural killer T cell, T follicular helper cell, Type 1 T-helper cell, and Type 17 T-helper cell) between high and low BMD patients. We obtained a total of 73 candidate genes based on modular genes and differential genes, and obtained 5 signature genes by least absolute shrinkage and selection operator and random forest model screening. ROC, principal component analysis, and t-distributed stochastic neighbor embedding down scaling analysis revealed that the 5 signature genes had good discriminatory ability between high and low BMD samples. A logistic regression model was constructed based on 5 signature genes, and both ROC and column line plots indicated that the model accuracy and applicability were good. Five signature genes were found to be associated with proteasome, mitochondria, and lysosome by gene set enrichment analysis. The real-time quantitative polymerase chain reaction results showed that the expression of the signature genes was significantly different between the 2 groups. HIST1H2AG, PYGM, NCKAP1, POMP, and LYPLA1 might play key roles in PMOP and be served as the biomarkers of PMOP.

MicroRNAs regulate the vicious cycle of vascular calcification-osteoporosis in postmenopausal women.

Menopause is a normal physiological process accompanied by changes in various physiological states. The incidence of vascular calcification (VC) increases each year after menopause and is closely related to osteoporosis (OP). Although many studies have investigated the links between VC and OP, the interaction mechanism of the two under conditions of estrogen loss remains unclear. MicroRNAs (miRNAs), which are involved in epigenetic modification, play a critical role in estrogen-mediated mineralization. In the past several decades, miRNAs have been identified as biomarkers or therapeutic targets in diseases. Thus, we hypothesize that these small molecules can provide new diagnostic and therapeutic approaches. In this review, we summarize the close interactions between VC and OP and the role of miRNAs in their interplay.

Identification of Transcripts with Shared Roles in the Pathogenesis of Postmenopausal Osteoporosis and Cardiovascular Disease.

Epidemiological evidence suggests existing comorbidity between postmenopausal osteoporosis (OP) and cardiovascular disease (CVD), but identification of possible shared genes is lacking. The skeletal global transcriptomes were analyzed in trans-iliac bone biopsies (n = 84) from clinically well-characterized postmenopausal women (50 to 86 years) without clinical CVD using microchips and RNA sequencing. One thousand transcripts highly correlated with areal bone mineral density (aBMD) were further analyzed using bioinformatics, and common genes overlapping with CVD and associated biological mechanisms, pathways and functions were identified. Fifty genes (45 mRNAs, 5 miRNAs) were discovered with established roles in oxidative stress, inflammatory response, endothelial function, fibrosis, dyslipidemia and osteoblastogenesis/calcification. These pleiotropic genes with possible CVD comorbidity functions were also present in transcriptomes of microvascular endothelial cells and cardiomyocytes and were differentially expressed between healthy and osteoporotic women with fragility fractures. The results were supported by a genetic pleiotropy-informed conditional False Discovery Rate approach identifying any overlap in single nucleotide polymorphisms (SNPs) within several genes encoding aBMD- and CVD-associated transcripts. The study provides transcriptional and genomic evidence for genes of importance for both BMD regulation and CVD risk in a large collection of postmenopausal bone biopsies. Most of the transcripts identified in the CVD risk categories have no previously recognized roles in OP pathogenesis and provide novel avenues for exploring the mechanistic basis for the biological association between CVD and OP.

Comprehensive analysis of circRNA expression profiles in postmenopausal women differing in bone mineral density.

Postmenopausal osteoporosis (PMOP) seriously endangers the bone health of older women. Although there are currently indicators to diagnose PMOP, early diagnostic biomarkers are lacking. Circular ribonucleic acid (circRNA) has a stable structure, regulates gene expression, participates in the pathological process of disease, and has the potential to become a biomarker. The purpose of this study was to investigate circRNAs that could be used to predict patients with early PMOP. Ribonucleic acid (RNA) sequencing was performed on peripheral blood leukocytes from 15 female patients to identify differential circRNAs between different groups. Using bioinformatics analysis, enrichment analysis was performed to discover relevant functions and pathways. CircRNA-micro ribonucleic acid (miRNA) interaction analysis and messenger ribonucleic acid (mRNA) prediction and network construction help us to understand the relationship between circRNA, miRNA, and mRNA. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate the gene expression of candidate circRNAs. We screened out 2 co-expressed differential circRNAs, namely hsa_circ_0060849 and hsa_circ_0001394. By analyzing the regulatory network, a total of 54 miRNAs and 57 osteoporosis-related mRNAs were identified, which, as potential downstream target genes of hsa_circ_0060849 and hsa_circ_0001394, may play a key role in the occurrence and development of PMOP. The occurrence and development of PMOP is regulated by circRNAs, and hsa_circ_0060849 and hsa_circ_0001394 can be used as new diagnostic markers and therapeutic targets for early PMOP.

Unraveling Key m6A Modification Regulators Signatures in Postmenopausal Osteoporosis through Bioinformatics and Experimental Verification.

OBJECTIVE: Bone marrow mesenchymal stem cells (BMSCs) show significant potential for osteogenic differentiation. However, the underlying mechanisms of osteogenic capability in osteoporosis-derived BMSCs (OP-BMSCs) remain unclear. This study aims to explore the impact of YTHDF3 (YTH N6-methyladenosine RNA binding protein 3) on the osteogenic traits of OP-BMSCs and identify potential therapeutic targets to boost their bone formation ability. METHODS: We examined microarray datasets (GSE35956 and GSE35958) from the Gene Expression Omnibus (GEO) to identify potential m6A regulators in osteoporosis (OP). Employing differential, protein interaction, and machine learning analyses, we pinpointed critical hub genes linked to OP. We further probed the relationship between these genes and OP using single-cell analysis, immune infiltration assessment, and Mendelian randomization. Our in vivo and in vitro experiments validated the expression and functionality of the key hub gene. RESULTS: Differential analysis revealed seven key hub genes related to OP, with YTHDF3 as a central player, supported by protein interaction analysis and machine learning methodologies. Subsequent single-cell, immune infiltration, and Mendelian randomization studies consistently validated YTHDF3's significant link to osteoporosis. YTHDF3 levels are significantly reduced in femoral head tissue from postmenopausal osteoporosis (PMOP) patients and femoral bone tissue from PMOP mice. Additionally, silencing YTHDF3 in OP-BMSCs substantially impedes their proliferation and differentiation. CONCLUSION: YTHDF3 may be implicated in the pathogenesis of OP by regulating the proliferation and osteogenic differentiation of OP-BMSCs.

circ_0134120: a new frontier in understanding postmenopausal osteoporosis pathogenesis.

Postmenopausal osteoporosis (OP) is a prevalent skeletal disease with not fully understood molecular mechanisms. This study aims to investigate the role of circular RNA (circRNA) in postmenopausal OP and to elucidate the potential mechanisms of the circRNA-miRNA-mRNA regulatory network. We obtained circRNA and miRNA expression profiles from postmenopausal OP patients from the Gene Expression Omnibus database. By identifying differentially expressed circRNAs and miRNAs, we constructed a circRNA-miRNA-mRNA network and identified key genes associated with OP. Further, through a range of experimental approaches, including dual-luciferase reporter assays, RNA pull-down experiments, and qRT-PCR, we examined the roles of circ_0134120, miR-590-5p, and STAT3 in the progression of OP. Our findings reveal that the interaction between circ_0134120 and miR-590-5p in regulating STAT3 gene expression is a key mechanism in OP, suggesting the circRNA-miRNA-mRNA network is a potential therapeutic target for this condition.

Interferon Regulatory Factor 4 (IRF4) Plays a Key Role in Osteoblast Differentiation of Postmenopausal Osteoporosis.

BACKGROUND: Postmenopausal osteoporosis (PMOP) is a prevalent disease, which features decreased bone mass, bone weakness and deteriorated bone microstructure in postmenopausal women. Although many factors have been revealed to contribute to the occurrence of PMOP, its mechanism remains undefined. This work aimed to identify significant changes in gene expression during PMOP formation and to examine the most valuable differential genes in postmenopausal osteoporosis versus the control group. METHODS: The GSE68303 dataset that contains 12 ovariectomize (OVX) experimental and 11 sham groups was downloaded and analyzed. The results indicated that interferon regulatory factor 4 (IRF4) might be a hub gene in the development of postmenopausal osteoporosis. Western blot and immunohistochemistry were carried out to evaluate IRF4 levels in thoracic vertebra extracts from OVX and Sham mice. To assess IRF4's impact on osteogenic differentiation in postmenopausal bone marrow mesenchymal stem cells (BM-MSCs), IRF4 overexpression (OV-IRF4) and knockdown (Sh-IRF4) plasmids were constructed. RESULTS: The results showed that comparing with the sham group, bone samples from the OVX group showed higher IRF4 expression. Alkaline phosphatase (ALP) staining revealed that IRF4 overexpression significantly inhibited ALP activity, while IRF4 knockdown promoted ALP activity in BM-MSCs. Simvastatin-treated OVX mice showed increased total bone volume/total tissue volume (BV/TV) and elevated Runx2 expression by immunohistochemical staining compared with the OVX group. CONCLUSIONS: This study demonstrated that IRF4 is associated with OVX induced osteoporosis, it can regulate bone stability by inhibiting the osteogenic differentiation BM-MSCs. This study may help enhance our understanding of the molecular mechanism of PMOP formation, providing new insights into estrogen defiance induced osteoporosis.

Relationship between polymorphisms and mutations at rs7125942 and rs3736228 of LRP5 gene and bone metabolism in postmenopausal women.

OBJECTIVE: To analyze the relationship between the polymorphism and mutation of rs7125942 and rs3736228 locus in the low-density lipoprotein receptor-related protein 5 (LRP5) genotype and bone mineral density (BMD) in postmenopausal women in Xinjiang, China, to provide a basis for prevention and treatment of the disease. METHODS: According to the results of dual-energy X-ray (DEXA) determination of BMD, the 136 subjects were divided into three groups: Group A: normal bone mass, Group B: osteopenia, Group C: osteoporosis. 1. Age, body, mass index (BMI), and menopause of all subjects were recorded. 2. Fasting blood glucose (FBG), glycosylated hemoglobin (HbA1c), calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), and clinical biochemical data were determined. 3. LRP5 locus polymorphisms were determined by time-of-flight mass spectrometry. RESULTS: 1. Compared with group A, the age, ALP, Cr, and BUN levels in group B and group C were increased, but UA levels were lower (P < 0.05), and Serum P was higher in the group C (P < 0.05). 2. There was no statistically significant difference in the prevalence of diabetes between the three groups (P > 0.05). 3. The ROC curves for different BMD sites such as L1, L2, L3, L4, L total, and femoral neck were 0.929, 0.955, 0.901, 0.914, 0.885, and 0.873 (P < 0.01). 4. At rs7125942 locus, there was statistically significant difference in the distribution of wild-type (CC) and mutant (CG) with the normal bone mass (NBM) group and the abnormal bone mass (ABM) group (P < 0.05). 5. At rs7125942 locus, compared with wild-type (CC), mutant (CG) had lower LDL and FPG in NBM group (P < 0.05), and lower serum ALP in the ABM group (P < 0.05). At rs3736228 locus, the BMD (Femoral neck) of mutant (CT/TT) was lower than that of wild-type (CC) in the NBM group (P < 0.05). 6. Age and menopausal years were negatively correlated with BMD of the femoral neck and L1-4 (P < 0.05), and BMI and TG were positively (P < 0.05), and the results of multiple linear regression analysis showed that age, BMI, and TG were both independent factors affecting BMD (P < 0.05).

Investigating the impact of Wnt pathway-related genes on biomarker and diagnostic model development for osteoporosis in postmenopausal females.

The Wnt signaling pathway is essential for bone development and maintaining skeletal homeostasis, making it particularly relevant in osteoporosis patients. Our study aimed to identify distinct molecular clusters associated with the Wnt pathway and develop a diagnostic model for osteoporosis in postmenopausal Caucasian women. We downloaded three datasets (GSE56814, GSE56815 and GSE2208) related to osteoporosis from the GEO database. Our analysis identified a total of 371 differentially expressed genes (DEGs) between low and high bone mineral density (BMD) groups, with 12 genes associated with the Wnt signaling pathway, referred to as osteoporosis-associated Wnt pathway-related genes. Employing four independent machine learning models, we established a diagnostic model using the 12 osteoporosis-associated Wnt pathway-related genes in the training set. The XGB model showed the most promising discriminative potential. We further validate the predictive capability of our diagnostic model by applying it to three external datasets specifically related to osteoporosis. Subsequently, we constructed a diagnostic nomogram based on the five crucial genes identified from the XGB model. In addition, through the utilization of DGIdb, we identified a total of 30 molecular compounds or medications that exhibit potential as promising therapeutic targets for osteoporosis. In summary, our comprehensive analysis provides valuable insights into the relationship between the osteoporosis and Wnt signaling pathway.

Heterogeneous osteoimmune profiles via single-cell transcriptomics in osteoporotic patients who fail bisphosphonate treatment.

Postmenopausal osteoporosis arises from imbalanced osteoclast and osteoblast activity, and mounting evidence suggests a role for the osteoimmune system in bone homeostasis. Bisphosphonate (BP) is an antiresorptive agent, but its treatment failure rate can be as high as 40%. Here, we performed single-cell RNA sequencing on peripheral immune cells from carefully selected postmenopausal women: non-osteoporotic, osteoporosis improved after BP treatment, and BP-failed cases. We found an increase in myeloid cells in patients with osteoporosis (specifically, T cell receptor+ macrophages). Furthermore, lymphoid lineage cells varied significantly, notably elevated natural killer cells (NKs) in the BP-failed group. Moreover, we provide fruitful lists of biomarkers within the immune cells that exhibit condition-dependent differences. The existence of osteoporotic- and BP-failure-specific cellular information flows was revealed by cell-cell interaction analysis. These findings deepen our insight of the osteoporosis pathology enhancing comprehension of the role of immune heterogeneity in postmenopausal osteoporosis and BP treatment failure.

Identifying the effective combination of acupuncture and traditional Chinese medicinal herbs for postmenopausal osteoporosis therapy through studies of their molecular regulation of bone homeostasis.

Worldwide, as the population age, osteoporosis is becoming increasingly common, and osteoporotic fractures have a significant economic burden. Postmenopausal women are the most susceptible to developing osteoporosis and the most critical time to prevent it is during the perimenopausal and early menopausal years. In this regard, we hypothesize rational combination of acupuncture and Traditional Chinese Medicine (TCM) in the form of herbal extract could prevent osteoporosis in women. Estrogen deficiency during menopause causes low-level inflammation that stimulates the formation of osteoclasts, the bone-resorbing cells, and simultaneously inhibits the viability and function of osteoblasts, the bone-forming cells. The most potent inflammatory cytokine in skeletal homeostasis is the receptor activator of nuclear factor kappa B ligand (RANKL) that stimulates osteoclast function. Conversely, the canonical Wnt pathway is essential for osteoblastogenesis and bone formation, and estrogen deficiency leads to diminished functioning of this pathway. TCM and acupuncture could target the RANKL and the Wnt pathway in favorable ways to prevent the accelerated bone loss experienced during the early menopausal stage and promote the gain in bone mass in postmenopausal women. In this review, we propose a rational combination of specific TCM and acupuncture targeting those signaling molecules/pathways by the drugs that are in clinical use for the treatment of postmenopausal osteoporosis. Our rational approach revealed that Danshen (Radix Salviae Miltiorrhizae) could exert a synergistic effect with acupuncture. We then propose a translational path for developing the putative combination in women with postmenopausal osteoporosis to curtail the risk of osteoporotic fractures.

Polymorphisms in the Runx2 and osteocalcin genes affect BMD in postmenopausal women: a systematic review and meta-analysis.

PURPOSE: Runx2 and osteocalcin have pivotal roles in bone homeostasis. Polymorphism of these two genes could alter the function of osteoblasts and consequently bone mineral density (BMD). Attempts to understand the relationship between these polymorphisms and BMD in postmenopausal women across a variety of populations have yielded inconsistent results. This meta-analysis seeks to define the relationship between these polymorphisms with BMD in postmenopausal women. METHODS: Eligible studies were identified from three electronic databases. Data were extracted from the eligible studies (4 studies on Runx2 and 6 studies on osteocalcin), and associations of Runx2 T > C and osteocalcin HindIII polymorphisms with BMD in postmenopausal women were assessed using standard difference in means (SDM) and 95% confidence intervals (CI) as statistical measures. RESULTS: A significant difference in the lumbar spine (LS) BMD in postmenopausal women was observed between the TT and CC homozygotes for the Runx2 T > C (SDM = -0.445, p-value = 0.034). The mutant genotypes (CC) showed significantly lower LS BMD in comparison to wild type genotypes under recessive model of genetic analysis (TC + TT vs. CC: SDM = -0.451, p-value = 0.032). For osteocalcin, HindIII polymorphism, the mutant genotypes (HH) was associated with significantly higher BMD for both LS and femoral neck (FN) than the wild type (hh) homozygotes (SDM = 0.152, p-value = 0.008 and SDM = 0.139, p-value = 0.016 for LS and FN, respectively). There was no association between total hip (TH) BMD and the osteocalcin HindIII polymorphism. CONCLUSIONS: Runx2 T > C and osteocalcin HindIII polymorphisms influence the level of BMD in postmenopausal women and may be used as predictive markers of osteoporosis.

Glycolithocholic acid increases the frequency of circulating Tregs through constitutive androstane receptor to alleviate postmenopausal osteoporosis.

BACKGROUND AND PURPOSE: Gut microbiota and their metabolic activity are important regulators of host immunity. However, the role of gut microbiota and their metabolic activity-mediated osteoimmunity in postmenopausal osteoporosis (PMO) remains unknown. This study aimed to explore the role of gut microbiota and their metabolic activity in PMO. EXPERIMENTAL APPROACH: 16S rDNA sequencing was used for analyzing the gut microbiota diversity of patients with PMO and rat models, and a targeted metabolism study was performed for analyzing metabolite levels. Flow cytometry was used for analyzing the frequency of immune cells. Micro-CT was used for analyzing bone damage in rat models. Fecal microbiota transplantation was performed for exploring the therapeutic effect of the gut microbiota on PMO. CD4+ T cells were co-cultured with bone marrow mesenchymal stem cells for evaluating their molecular mechanisms. KEY RESULTS: Patients with PMO exhibited reduced gut microbiota diversity, and fecal glycolithocholic acid (GLCA) levels correlated with the degree of osteoporosis. GLCA levels in the gut were positively correlated with the frequency of circulating Tregs in ovariectomized rats. Restoration of the gut microbiota alleviated osteoporosis in ovariectomized rats. Circulating GLCA augmented CD4+ T cell differentiation into Tregs via constitutive androstane receptors. The increased frequency of Tregs further promoted the osteogenic differentiation of bone marrow mesenchymal stem cells to alleviate osteoporosis. CONCLUSION AND IMPLICATIONS: GLCA alleviated PMO by increasing the frequency of circulating Tregs, acting via the constitutive androstane receptor. This study reveals a new strategy for the treatment of PMO, with GLCA as a potential drug candidate.

Identification of a potential signature to predict the risk of postmenopausal osteoporosis.

BACKGROUND: Postmenopausal osteoporosis (PMOP) is related to the elevated risk of fracture in postmenopausal women. Thus, to effectively predict the occurrence of PMOP, we explored a novel gene signature for the prediction of PMOP risk. METHODS: The WGCNA analysis was conducted to identify the PMOP-related gene modules based on the data from GEO database (GSE56116 and GSE100609). The "limma" R package was applied for screening differentially expressed genes (DEGs) based on the data from GSE100609 dataset. Next, LASSO Cox algorithm were applied to identify valuable PMOP-related risk genes and construct a risk score model. GSEA was then conducted to analyze potential signaling pathways between high-risk (HR) score and low-risk (LR) score groups. RESULTS: A novel risk model with five PMOP-related risk genes (SCUBE3, TNNC1, SPON1, SEPT12 and ULBP1) was developed for predicting PMOP risk status. RT-qPCR and western blot assays validated that compared to postmenopausal non-osteoporosis (non-PMOP) patients, SCUBE3, ULBP1, SEPT12 levels were obviously elevated, and TNNC1 and SPON1 levels were reduced in blood samples from PMOP patients. Additionally, PMOP-related pathways such as MAPK signaling pathway, PI3K-Akt signaling pathway and HIF-1 signaling pathway were significantly activated in the HR-score group compared to the LR-score group. The circRNA-gene-miRNA and gene-transcription factor networks showed that 533 miRNAs, 13 circRNAs and 40 TFs might be involved in regulating the expression level of these five PMOP-related genes. CONCLUSION: Collectively, we developed a PMOP-related gene signature based on SCUBE3, TNNC1, SPON1, SEPT12 and ULBP1 genes, and higher risk score indicated higher risk suffering from PMOP.

Systems genetics and bioinformatics analyses using ESR1-correlated genes identify potential candidates underlying female bone development.

Estrogen receptor α (ESR1) is involved in E2 signaling and plays a major role in postmenopausal bone loss. However, the molecular network underlying ESR1 has not been explored. We used systems genetics and bioinformatics to identify important genes associated with Esr1 in postmenopausal bone loss. We identified ~2300 Esr1-coexpressed genes in female BXD bone femur, functional analysis of which revealed 'osteoblast signaling' as the most enriched pathway. PPI network led to the identification of 25 'female bone candidates'. The gene-regulatory analysis revealed RUNX2 as a key TF. ANKRD1 and RUNX2 were significantly different between osteoporosis patients and healthy controls. Sp7, Col1a1 and Pth1r correlated with multiple femur bone phenotypes in BXD mice. miR-3121-3p targeted Csf1, Ankrd1, Sp7 and Runx2. ß-estradiol treatment markedly increased the expression of these candidates in mouse osteoblast. Our study revealed that Esr1-correlated genes Ankrd1, Runx2, Csf1 and Sp7 may play important roles in female bone development.