Polymorphisms in genes in the RANKL/RANK/OPG pathway are associated with bone mineral density at different skeletal sites in post-menopausal women

Osteoprotegerin Gene as a Biomarker in the Development of Osteoporosis in Postmenopausal Women

Osteoporosis is a multifactorial and polygenic disease caused by an imbalance between osteoclastogenesis and osteoblastogenesis, leading to a decrease in bone mineral density and the occurrence of disorders in the microarchitecture and metabolism of bone tissue. In postmenopausal women, there is a significant decrease in the production of estrogens, which play a key role in maintaining proper bone mineral density. Estrogens have an inhibitory effect on the development and activity of osteoclasts by reducing the synthesis of pro-resorption cytokines and stimulating the expression of osteoprotegerin (OPG). Osteoprotegerin is a cytokine that prevents bone loss by inhibiting the process of osteoclastogenesis, reducing bone resorption. The aim of our study was to determine the influence of the rs3102735 (-163A>G), rs3134070 (-245T>G), rs207361 (-950T>C), rs7844539 (6890A>C), and rs2073618 (1181G>C) polymorphisms of the OPG gene on the risk of osteoporosis and osteopenia in postmenopausal Polish women. The study included 802 unrelated women (osteoporosis: n = 317, osteopenia: n = 110, controls: n = 375) at postmenopausal age (54.7 ± 8.6 years). Genetic analysis was performed using real-time PCR. BMD values as well as clinical and bone parameters with the tested polymorphisms were analyzed among the study population. Analysis of the PPARG rs1801282 variants did not show any association with the risk of osteoporosis and osteopenia. However, for the OPG rs207361 polymorphism, we observed a statistically significant association with the risk of osteoporosis, suggesting that the OPG rs207361 variant may be one of the genetic markers associated with the pathogenesis of osteoporosis.

Conjugated linoleic acid and glucosamine supplements may prevent bone loss in aging by regulating the RANKL/RANK/OPG pathway

The skeleton is a living organ that undergoes constant changes, including bone formation and resorption. It is affected by various diseases, such as osteoporosis, osteopenia, and osteomalacia. Nowadays, several methods are applied to protect bone health, including the use of hormonal and non-hormonal medications and supplements. However, certain drugs like glucocorticoids, thiazolidinediones, heparin, anticonvulsants, chemotherapy, and proton pump inhibitors can endanger bone health and cause bone loss. New studies are exploring the use of supplements, such as conjugated linoleic acid (CLA) and glucosamine, with fewer side effects during treatment. Various mechanisms have been proposed for the effects of CLA and glucosamine on bone structure, both direct and indirect. One mechanism that deserves special attention is the regulatory effect of RANKL/RANK/OPG on bone turnover. The RANKL/RANK/OPG pathway is considered a motive for osteoclast maturation and bone resorption. The cytokine system, consisting of the receptor activator of the nuclear factor (NF)-kB ligand (RANKL), its receptor RANK, and its decoy receptor, osteoprotegerin (OPG), plays a vital role in bone turnover. Over the past few years, researchers have observed the impact of CLA and glucosamine on the RANKL/RANK/OPG mechanism of bone turnover. However, no comprehensive study has been published on these supplements and their mechanism. To address this gap in knowledge, we have critically reviewed their potential effects. This review aims to assist in developing efficient treatment strategies and focusing future studies on these supplements.

Osteoprotegerin genetic polymorphisms and their influence on therapeutic response to ibandronate in postmenopausal osteoporotic females

OBJECTIVES

The present study investigated osteoprotegerin (OPG) genetic polymorphisms and their influence on the therapeutic response to ibandronate in postmenopausal osteoporotic females.

METHODS

This case-control study included 135 postmenopausal females (89 osteoporotic females and 46 non-osteoporotic females). Each osteoporotic patient received a monthly 150 mg ibandronate tablet for six months, and blood samples were taken before and after treatment. Bone mineral density (BMD) was measured using DEXA Scan. Three SNPs (A163G, T245G, and G1181C) of the OPG gene were selected for analysis.

RESULTS

Serum OPG levels were significantly lower in osteoporotic subjects than in the control group. The percentage changes in OPG levels in the osteoporotic group before and after treatment with ibandronate were significant (p < .001). After six months of therapy with ibandronate, the percentage changes in OPG levels with AA, TT, TC, GC, and GG genotypes were significant. Following six months of ibandronate treatment, the AA genotype of rs3134069, TT, TC genotypes of rs3102735, GG, and GC genotypes of rs2073618 SNP showed a significant increase in OPG levels. Age, BMI, and GC polymorphism (rs2073618 (G/C) G1181C) were inversely associated with low BMD. Adjusted odds ratios (OR) showed that BMI, GC, GG polymorphism (rs2073618 (G/C) G1181C) and TC polymorphism (rs3102735 (T/C) A163G) were inversely associated with low BMD.

CONCLUSION

The inverse association of rs2073618 and rs3102735 with low BMD indicates the protective role of these SNPs in our population. More research is needed to replicate these results in another cohort and to determine the molecular processes by which such SNPs may influence BMD.

Genomic Medicine in Periodontal Disease: Old Issue, New Insights

Genetic variability is the main cause of phenotypic variation. Some variants may be associated with several diseases and can be used as risk biomarkers, identifying animals with higher susceptibility to develop the pathology. Genomic medicine uses this genetic information for risk calculation, clinical diagnosis and prognosis, allowing the implementation of more effective preventive strategies and/or personalized therapies. Periodontal disease (PD) is the inflammation of the periodontium induced mainly by bacterial plaque and is the leading cause of tooth loss. Microbial factors are responsible for the PD initiation; however, several studies support the genetic influence on the PD progression. The main purpose of the present publication is to highlight the main steps involved in the genomic medicine applied to veterinary patients, describing the flowchart from the characterization of the genetic variants to the identification of potential associations with specific clinical data. After investigating which genes might potentially be implicated in canine PD, the RANK gene, involved in the regulation of osteoclastogenesis, was selected to illustrate this approach. A case-control study was performed using DNA samples from a population of 90 dogs – 50 being healthy and 40 with PD. This analysis allowed for the discovery of four new intronic variations that were banked in GenBank (g.85A>G, g.151G>T, g.268A>G and g.492T>C). The results of this study are not intended to be applied exclusively to PD. On the contrary, this genetic information is intended to be used by other researchers as a foundation for the development of multiple applications in the veterinary clinical field.

Genetic Association of rs1021188 and DNA Methylation Signatures of TNFSF11 in the Risk of Conductive Hearing Loss

Otosclerosis (OTSC) is a complex bone disorder of the otic capsule, which causes conductive hearing impairment in human adults. The dysregulation of the signaling axis mediated by the receptor activator of nuclear factor-kappa-B (RANK), RANK ligand (RANKL), and osteoprotegerin has been widely attributed to the context of metabolic bone disorders. While genetic associations and epigenetic alterations in the TNFSF11 gene (RANKL) have been well-linked to metabolic bone diseases of the skeleton, particularly osteoporosis, they have never been addressed in OTSC. This study aimed to assess whether the genetic association of rs1021188 polymorphism in the upstream of TNFSF11 and the DNA methylation changes in its promoter CpG-region reveal the susceptibility of OTSC. Peripheral blood DNA samples were collected from unrelated Tunisian-North African subjects for genotyping (109 cases and 120 controls) and for DNA methylation analysis (40 cases and 40 controls). The gender-stratified analysis showed that the TNFSF11 rs1021188 C/T was associated with OTSC in men (p = 0.023), but not in women (p = 0.458). Individuals with CC genotype were more susceptible to OTSC, suggesting an increased risk to disease development. Using publicly available data, the rs1021188 was within a cluster grouping the subpopulations with African ethnicity. Moreover, 26 loci in the TNFSF11 gene were in linkage disequilibrium with rs1021188, revealing relative similarities between different populations. Significant differences in both DNA methylation and unmethylation status were detected with 4.53- and 4.83-fold decreases in the global DNA methylation levels in female and male OTSC groups, respectively. These changes could contribute to an increased risk of OTSC development. Bioinformatic analyses indicated that each of the rs1021188 variations and the DNA methylation changes in the promoter CpG-sites within TNFSF11 may play an important role in its transcription regulation. To our knowledge, this is the first study that investigates an independent effect of the rs1021188 polymorphism and DNA hypomethylation of TNFSF11 promoter in OTSC. Genetic and epigenetic changes in the regulatory regions of TNFSF11 could offer new molecular insights into the understanding of the complexity of OTSC.

Incorporation of Bone Morphogenetic Protein-2 and Osteoprotegerin in 3D-Printed Ti6Al4V Scaffolds Enhances Osseointegration Under Osteoporotic Conditions

Osteoporosis is an age-related metabolic disease that results in limited bone regeneration capacity and excessive osteoclast activity. After arthroplasty in patients with osteoporosis, poor interface osseointegration resulting from insufficient bone regeneration ability often leads to catastrophic complications such as prosthesis displacement and loosening and periprosthetic fractures. In this study, we prepared a thermosensitive hydrogel loaded with bone morphogenetic protein-2 (BMP-2) to promote osteogenesis and osteoprotegerin (OPG) to inhibit excessive osteoclast activity. To construct three-dimensional (3D)-printed composite scaffolds for implantation, a hydrogel loaded with drugs was injected into porous Ti6Al4V scaffolds. The 3D-printed composite scaffolds showed good biocompatibility and sustained release of BMP-2 and OPG for more than 20 days. In vitro experiments indicated that composite scaffolds promoted osteogenic differentiation and reduced the osteoclastic activation simultaneously. Remarkably, immunofluorescence staining, micro-CT, histological, and biomechanical tests demonstrated that the sustained release of both BMP-2 and OPG from composite scaffolds significantly improved bone ingrowth and osseointegration in osteoporotic defects. In conclusion, this study demonstrated that the BMP-2- and OPG-loaded 3D-printed composite scaffolds can potentially promote osseointegration for osteoporotic patients after joint replacement.

Genetic Mutations in TNFSF11 Were Associated With the Chronicity of Hepatitis C Among Chinese Han Population

Background: Recently, several studies have reported that the host immune response can be related to the RANKL/RANK/OPG signaling pathway. However, the associations of TNFSF11, TNFRSF11A, and TNFRSF11B gene polymorphisms in the RANKL/RANK/OPG pathway with hepatitis C virus (HCV) infection outcomes remain unclear.

Methods: In this case-control study, 768 persistent HCV infection and 503 spontaneous HCV clearance cases, and 1,259 control subjects were included. The Taman-MGB probe method was utilized to detect TNFSF11 rs9525641, TNFRSF11A rs8686340, and TNFRSF11B rs2073618 genotypes. The distribution of three single nucleotide polymorphisms (SNPs) genotypes was analyzed using stata14.0.

Results: SNPs rs9525641, rs8086340, and rs2073618 genotype frequencies followed the Hardy-Weinberg natural population equilibrium (p = 0.637, 0.250, and 0.113, respectively). Also, rs9525641 was significantly associated with HCV chronicity risk in recessive (OR = 1.203, 95% CI: 1.018–1.420, p = 0.030) and additive models (OR = 1.545, 95% CI: 1.150–2.075, p = 0.004). The stratified analysis showed that rs9525641 variant genotypes were associated with HCV chronicity among people older than 50 years (OR =1.562, 95% CI: 1.079–2.262, p = 0.018), females (OR = 1.667, 95% CI: 1.145–2.429, p = 0.008), ALT <40 U/L (OR = 1.532, 95% CI: 1.074–2.286, p = 0.018), and AST < 40 U/L (OR = 1.552, 95% CI: 1.095–2.201, p = 0.014).

Conclusion:TNFRSF11 rs9525641 was significantly associated with HCV chronicity in the Chinese population.

Association of RANKL and OPG Gene Polymorphism in Arab Women with and without Osteoporosis

Receptor activator of the nuclear factor-κB ligand (RANKL) and osteoprotegerin genes (OPG) were identified as susceptible loci for postmenopausal osteoporosis (PMO) in various ethnicities, but neither have been studied in an Arabian population. Hence, the current study aimed to fill this gap. A total of 372 postmenopausal women (174 osteoporosis (OP) and 198 control group (CTRs)) were genotyped for four SNPs: rs2277438A/G and rs9533156T/C (RANKL), and rs2073618C/G and rs3102735T/C (OPG). Anthropometrics, bone mineral density, 25(OH)D and several other bone markers were measured. The frequency distribution of the heterozygous CG genotype of rs2073618 (OPG) was lower in the OP (36.8%) than in CTRs (47%) (OR: 0.6, 95% CI: 0.3–0.97; p = 0.041). No differences in the allelic/genotypic frequencies were detected between the two groups for all other studied SNPs. However, the heterozygous TC genotype of rs3102735 (OPG) was associated significantly with lower BMD at the femoral neck in OP subjects (p = 0.04). The homozygous rare CC genotype of rs9533156 (RANKL) was associated with lower 25(OH)D levels in CTRs (p = 0.032). In contrast, heterozygous AG genotype of rs2277438 (RANKL) is associated with lower 25(OH)D in the OP group (p = 0.02). Our results suggest that RANKL SNPs may impact 25(OH)D levels and that OPG SNP rs2073618A/G is a significant genetic risk factor for PMO Saudi Arabian women.

RANKL is a new Epigenetic Biomarker for the Vasomotor Symptom During Menopause

During menopausal transition, decreased level of estrogen brings a number of physiological problems and hormonal changes. In this study, promoter methylation of RANKL and FSHR genes were identified in 30 premenopausal and 35 postmenopausal women using methylation-specific high resolution melting (MS-HRM) analysis. The statistical analyses and their association with patient characteristics were performed by Pearson χ² and Fisher's exact test (p <0.05). The methylated RANKL gene was detected in 16 postmenopausal cases, and 12 (75.0%) of the RANKL methylated cases had hot flashes (p = 0.024). The methylated FSHR gene was detected in 18 postmenopausal cases, and 13 (75.0%) of the methylated cases had hot flashes (p = 0.028). In vitro studies demonstrated the association between RANKL expression, FSH level and hot flashes in the mouse. Although lack of epigenetic studies in this field proves our results crucial and therefore, our results showed magnitude of epigenetic profiles of Turkish Cypriot post-menopausal women. This was the first study which has investigated the RANKL and FSHR methylation and their relationship with hot flashes in postmenopausal women.

Identifying Pleiotropic SNPs Associated With Femoral Neck and Heel Bone Mineral Density

Background

Genome-wide association studies (GWASs) routinely identify loci associated with risk factors for osteoporosis. However, GWASs with relatively small sample sizes still lack sufficient power to ascertain the majority of genetic variants with small to modest effect size, which may together truly influence the phenotype. The loci identified only account for a small percentage of the heritability of osteoporosis. This study aims to identify novel genetic loci associated with DXA-derived femoral neck (FNK) bone mineral density (BMD) and quantitative ultrasound of the heel calcaneus estimated BMD (eBMD), and to detect shared/causal variants for the two traits, to assess whether the SNPs or putative causal SNPs associated with eBMD were also associated with FNK-BMD.

Methods

Novel loci associated with eBMD and FNK-BMD were identified by the genetic pleiotropic conditional false discovery rate (cFDR) method. Shared putative causal variants between eBMD and FNK-BMD and putative causal SNPs for each trait were identified by the colocalization method. Mendelian randomization analysis addresses the causal relationship between eBMD/FNK-BMD and fracture.

Results

We identified 9,500 (cFDR < 9.8E-6), 137 (cFDR < 8.9E-4) and 124 SNPs associated with eBMD, FNK-BMD, and both eBMD and FNK-BMD, respectively, with 37 genomic regions where there was a SNP that influences both eBMD and FNK-BMD. Most genomic regions only contained putative causal SNPs associated with eBMD and 3 regions contained two distinct putative causal SNPs influenced both traits, respectively. We demonstrated a causal effect of FNK-BMD/eBMD on fracture.

Conclusion

Most of SNPs or putative causal SNPs associated with FNK-BMD were also associated with eBMD. However, most of SNPs or putative causal SNPs associated with eBMD were not associated with FNK-BMD. The novel variants we identified may help to account for the additional proportion of variance of each trait and advance our understanding of the genetic mechanisms underlying osteoporotic fracture.

Mapping theme trends and recognizing hot spots in postmenopausal osteoporosis research: a bibliometric analysis

Background

This study aimed to draw a series of scientific maps to quantitatively and qualitatively evaluate hot spots and trends in postmenopausal osteoporosis research using bibliometric analysis.

Methods

Scientific papers published on postmenopausal osteoporosis were extracted from the Web of Science Core Collection and PubMed database. Extracted information was analyzed quantitatively with bibliometric analysis by CiteSpace, the Online Analysis Platform of Literature Metrology and Bibliographic Item Co-Occurrence Matrix Builder (BICOMB). To explore the hot spots in this field, co-word biclustering analysis was conducted by gCLUTO based on the major MeSH terms/MeSH subheading terms-source literatures matrix.

Results

We identified that a total of 5,247 publications related to postmenopausal osteoporosis were published between 2013 and 2017. The overall trend decreased from 1,071 literatures in 2013 to 1,048 literatures in 2017. Osteoporosis International is the leading journal in the field of postmenopausal osteoporosis research, both in terms of impact factor score (3.819) and H-index value (157). The United States has retained a top position and has exerted a pivotal influence in this field. The University of California, San Francisco was identified as a leading institution for research collaboration, and Professors Reginster and Kanis have made great achievements in this area. Eight research hot spots were identified.

Conclusions

Our study found that in the past few years, the etiology and drug treatment of postmenopausal osteoporosis have been research hot spots. They provide a basis for the study of the pathogenesis of osteoporosis and guidelines for the drug treatment of osteoporosis.

Association between polymorphisms in GGPS1 and RANKL genes and postmenopausal osteoporosis in Romanian women

Objectives: This study aimed to assess the relationship between bone mineral density, fragility fractures, fracture risk and polymorphisms of two osteoporosis-candidate genes (GGPS1 and RANKL) in Romanian women with postmenopausal osteoporosis. Methods: An analytical, prospective, transversal, observational, case-control study on 364 postmenopausal women, of which 228 were previously diagnosed with osteoporosis, was carried out between June 2016 and August 2017 in Cluj Napoca, Romania. Clinical data and blood samples were collected from all study participants. Polymorphisms in GGPS1 and RANKL genes were genotyped using TaqMan SNP Genotyping assays, run on a QuantStudio 3 real-time PCR machine. Results: The CT genotype in GGPS1 rs10925503 was associated with significant lower bone mineral density values at lumbar spine and femoral neck sites and a higher fracture risk compared to controls. No significant association was found between genotypes of RANKL rs2277439 with bone mineral density or fracture risk compared to the healthy controls. Conclusions: Our study showed a strong association between low bone mineral density and genotype CT of GGPS1 rs10925503 polymorphisms. No association was found for RANKL rs2277439 polymorphism.

Applying vibration in early postmenopausal osteoporosis promotes osteogenic differentiation of bone marrow-derived mesenchymal stem cells and suppresses postmenopausal osteoporosis progression

We aimed to evaluate whether applying low magnitude vibration (LMV) in early postmenopausal osteoporosis (PMO) suppresses its progression, and to investigate underlying mechanisms. Rats were randomly divided into Sham (Sham-operated), Sham+V, OVX (ovariectomized), OVX+E2 (estradiol benzoate), OVX+V (LMV at 12–20 weeks postoperatively), and OVX+Vi (LMV at 1–20 weeks postoperatively) groups. LMV was applied for 20 min once daily for 5 days weekly. V rats were loaded with LMV at 12–20 weeks postoperatively. Vi rats were loaded with LMV at 1–20 weeks postoperatively. Estradiol (E2) rats were intramuscularly injected at 12–20 weeks postoperatively once daily for 3 days. The bone mineral densities (BMDs), biomechanical properties, and histomorphological parameters of tibiae were analyzed. In vitro, rat bone marrow-derived mesenchymal stem cells (rBMSCs) were subjected to LMV for 30 min daily for 5 days, or 17β-E2 with or without 1-day pretreatment of estrogen receptor (ER) inhibitor ICI 182,780 (ICI). The mRNA and protein expresion were performed. Data showed that LMV increased BMD, bone strength, and bone mass of rats, and the effects of Vi were stronger than those of E2. In vitro, LMV up-regulated the mRNA and protein expressions of Runx2, Osx, Col I, and OCN and down-regulated PPARγ, compared with E2. The effects of both LMV and E2 on rBMSCs were inhibited by ICI. Altogether, LMV in early PMO suppresses its progression, which is associated with osteogenic differentiation of rBMSCs via up-regulation of ERα and activation of the canonical Wnt pathway. LMV may therefore be superior to E2 for the suppression of PMO progression.

Why SNP rs227584 is associated with human BMD and fracture risk? A molecular and cellular study in bone cells

A large number of SNPs significant for osteoporosis (OP) had been identified by genome-wide association studies. However, the underlying association mechanisms were largely unknown. From the perspective of protein phosphorylation, gene expression regulation, and bone cell activity, this study aims to illustrate association mechanisms for representative SNPs of interest. We utilized public databases and bioinformatics tool to identify OP-associated SNPs which potentially influence protein phosphorylation (phosSNPs). Associations with hip/spine BMD, as well as fracture risk, in human populations for one significant phosSNP, that is, rs227584 (major/minor allele: C/A, EAS population) located in C17orf53 gene, were suggested in prior meta-analyses. Specifically, carriers of allele C had significant higher BMD and lower risk of low-trauma fractures than carriers of A. We pursued to test the molecular and cellular functions of rs227584 in bone through osteoblastic cell culture and multiple assays. We identified five phosSNPs significant for OP (P < 0.01). The osteoblastic cells, which was transfected with wild-type C17orf53 (allele C at rs227584, P126), demonstrated specific interaction with NEK2 kinase, increased expression levels of osteoblastic genes significantly (OPN, OCN, COL1A1, P < 0.05), and promoted osteoblast growth and ALP activity, in contrast to those transfected with mutant C17orf53 (allele A at rs227584, T126). In the light of the consistent evidences between the present functional study in human bone cells and the prior association studies in human populations, we conclude that the SNP rs227584, via altering protein-kinase interaction, regulates osteoblastic gene expression, influences osteoblast growth and activity, hence to affect BMD and fracture risk in humans.

VDR and TNFSF11 polymorphisms are associated with osteoporosis in Thai patients

Determining molecular markers for osteoporosis may be valuable for improving the quality of life of affected elderly patients by aiding in early detection and disease management. In the present study, the association between single nucleotide polymorphisms (SNPs) of the vitamin D receptor (VDR) and tumour necrosis factor superfamily number 11 (TNFSF11) genes and the susceptibility of developing osteoporosis was investigated in a Thai female cohort. The study group consisted of 105 Thai postmenopausal patients diagnosed with osteoporosis and 132 healthy Thai postmenopausal female volunteers. DNA extracted from blood samples was used to genotype the VDR and TNFSF11 genes using polymerase chain reaction-restriction fragment length polymorphism and sequencing analysis. For VDR, the frequencies of the genotypes TT, CT and CC for the TaqI SNP (rs731236) were 87.88, 11.36 and 0.76%, respectively, in the control group, while in the osteoporosis cohort were 92.38, 5.71 and 1.91%, respectively. For the FokI SNP (rs2228570), the frequencies of the genotypes CC, CT and TT were 31.06, 55.30 and 13.64%, respectively, in the control group, and in the osteoporosis group were 29.52, 43.81 and 26.67%, respectively. For BsmI SNP (rs1544410), the frequencies of the genotypes GG, GA and AA were 78.03, 18.94 and 3.03%, respectively, in control group, and in the osteoporosis group were 80.95, 18.10 and 0.95%, respectively. The significant risk of osteoporosis associated with the FokI SNP was determined. The odds ratio (95% confidence interval) was 2.30 (1.14-4.69; P=0.01) among patients with osteoporosis with TT as the susceptibility genotype. For TNFSF11, the frequencies of the genotypes TT, CT and CC for the -290C>T SNP (rs9525641) in the control group were 36.36, 50.76 and 12.88%, respectively, while in the osteoporosis group were 31.43, 56.19 and 12.38%, respectively. For the -643C>T SNP (rs9533156), the frequencies of the genotypes TT, CT and CC in the control group were 35.61, 48.48 and 15.91%, respectively, while in the osteoporosis group were 32.38, 55.24 and 12.38%, respectively. For the -693G>C SNP (rs9533155), the frequencies of the genotypes CC, CG, and GG in the control group were 39.39, 46.97 and 13.64%, respectively, and in the osteoporosis group were 36.19, 53.33 and 10.48%, respectively. No significant associations of the TNFSF11 SNPs with osteoporosis were determined; however, it was notable that the GCT haplotype of TNFSF11 may be a protective haplotype for osteoporosis. Therefore, it was concluded that the SNP FokI of VDR may be a potential molecular biomarker for the development of osteoporosis in Thai females.

Sirt1/Foxo Axis Plays a Crucial Role in the Mechanisms of Therapeutic Effects of Erzhi Pill in Ovariectomized Rats

Background. Erzhi pill (EZP), a traditional Chinese herbal formula, has been widely used to treat postmenopausal osteoporosis (PMOP) in China. However, its molecular mechanisms remain unclear. The aim of the present study is to investigate the antiosteoporotic effect of EZP on an ovariectomized rat model of PMOP. We performed the biomarkers of bone metabolism disorder, bone morphology, bone mineral density (BMD), and bone biomechanics to confirm the successful establishment of the PMOP model. We then investigated the expression of biomarkers related to the Sirt1/Foxo axis. We also examined microRNA-132 (miR-132), a regulator in the Sirtuin1 (Sirt1) expression. The bone metabolism disorder, bone morphology, BMD, and bone biomechanics in ovariectomized rats were improved by EZP administration. The antiosteoporotic effect of EZP was confirmed. We also found that the expressions of Sirt1, Runx2, Foxo1, and Foxo3a were downregulated in ovariectomized rats, while being then upregulated by EZP administration. And the expression of PPAR-γ and miR-132 was upregulated in ovariectomized rats and then downregulated by EZP administration. These results provided evidence that Sirt1/Foxo axis related mechanism may play a crucial role in the therapeutic effects of EZP, indicating that Sirt1/Foxo axis can be considered as a potential therapeutic target for PMOP in the future.

Interaction between LRP5 and periostin gene polymorphisms on serum periostin levels and cortical bone microstructure

We investigated the interaction between periostin SNPs and the SNPs of the genes assumed to modulate serum periostin levels and bone microstructure in a cohort of postmenopausal women. We identified an interaction between LRP5 SNP rs648438 and periostin SNP rs9547970 on serum periostin levels and on radial cortical porosity.

PURPOSE

The purpose of this study is to investigate the interaction between periostin gene polymorphisms (SNPs) and other genes potentially responsible for modulating serum periostin levels and bone microstructure in a cohort of postmenopausal women.

METHODS

In 648 postmenopausal women from the Geneva Retirees Cohort, we analyzed 6 periostin SNPs and another 149 SNPs in 14 genes, namely BMP2, CTNNB1, ESR1, ESR2, LRP5, LRP6, PTH, SPTBN1, SOST, TGFb1, TNFRSF11A, TNFSF11, TNFRSF11B and WNT16. Volumetric BMD and bone microstructure were measured by high-resolution peripheral quantitative computed tomography at the distal radius and tibia.

RESULTS

Serum periostin levels were associated with radial cortical porosity, including after adjustment for age, BMI, and years since menopause (p = 0.036). Sixteen SNPs in the ESR1, LRP5, TNFRSF11A, SOST, SPTBN1, TNFRSF11B and TNFSF11 genes were associated with serum periostin levels (p range 0.03-0.001) whereas 26 SNPs in 9 genes were associated with cortical porosity at the radius and/or at the tibia. WNT 16 was the gene with the highest number of SNPs associated with both trabecular and cortical microstructure. The periostin SNP rs9547970 was also associated with cortical porosity (p = 0.04). In particular, SNPs in LRP5, ESR1 and near the TNFRSF11A gene were associated with both cortical porosity and serum periostin levels. Eventually, we identified an interaction between LRP5 SNP rs648438 and periostin SNP rs9547970 on serum periostin levels (interaction p = 0.01) and on radial cortical porosity (interaction p = 0.005).

CONCLUSION

These results suggest that periostin expression is genetically modulated, particularly by polymorphisms in the Wnt pathway, and is thereby implicated in the genetic variation of bone microstructure.

The prognostic role of RANK SNP rs34945627 in breast cancer patients with bone metastases

Receptor activator of NF-kB (RANK) pathway regulates bone remodeling and is involved in breast cancer (BC) progression. Genetic polymorphisms affecting RANK-ligand (RANKL) and osteoprotegerin (OPG) have been previously associated with BC risk and bone metastasis (BM)-free survival, respectively. In this study we conducted a retrospective analysis of the association of five missense RANK SNPs with clinical characteristics and outcomes in BC patients with BM. SNP rs34945627 had an allelic frequency of 12.5% in BC patients, compared to 1.2% in the control group (P = 0.005). SNP rs34945627 was not associated with any clinicopathological characteristics, but patients presenting SNP rs34945627 had decreased disease-free survival (DFS) (log-rank P = 0.039, adjusted HR 2.29, 95% CI 1.04–5.08, P = 0.041), and overall survival (OS) (log-rank P = 0.019, adjusted HR 4.32, 95% CI 1.55–12.04, P = 0.005). No differences were observed regarding bone disease-free survival (log-rank P = 0.190, adjusted HR 1.68, 95% CI 0.78–3.66, P = 0.187), time to first skeletal-related event (log-rank P = 0.753, adjusted HR 1.28, 95% CI 1.42–3.84; P = 0.665), or time to bone progression (log-rank P = 0.618, adjusted HR 0.511, 95% CI 0.17–1.51; P = 0.233). Our analysis shows that RANK SNP rs34945627 has a high allelic frequency in patients with BC and BM, and is associated with decreased DFS and OS.

RANKL/RANK/OPG Polymorphisms and Heel Quantitative Ultrasound in Young Adults

BACKGROUND

The receptor activator of the nuclear factor-kappa B ligand (RANKL), the receptor activator of nuclear factor-kappa B (RANK), and the osteoprotegerin (OPG) signaling pathway play an important role in the regulation of bone remodeling and osteoclast differentiation. Quantitative ultrasound (QUS) is a relatively recent and noninvasive method providing structural information on microstructure, bone elasticity, and connectivity. However, in contrast to bone mineral density measurements, the possible association of the RANKL/RANK/OPG pathway with heel QUS has not been analyzed.

OBJECTIVES

The aim of this study was to assess, for the first time, the contribution of the RANKL/RANK/OPG pathway genes in the genetic background of heel QUS parameters.

METHODS

Ten single-nucleotide polymorphisms (SNPs) of RANKL (rs9594759, rs12585014, rs7988338, rs2148073), RANK (rs1805034, rs12458117, rs3018362), and OPG (rs4355801, rs3102735, rs2073618) were selected as genetic markers and genotyped using Open Array technology in 575 self-reported Caucasian individuals aged 18-25. Bone mass in the right calcaneus was estimated with QUS to obtain the broadband ultrasound attenuation (BUA) measurement (dB/MHz). Linear regression analyses were performed to test the possible association between the SNPs and BUA.

RESULTS

Linear regression analysis of all the tested SNPs revealed no significant association with the BUA parameter after adjusting for age, gender, weight, height, physical activity, and calcium intake. The lowest p-value was observed for the rs9594759 RANKL polymorphism and heel QUS (p = .06; b* = -.075, 95% CI [-0.960, 0.028]).

CONCLUSION

Our results suggest that the polymorphism of the RANKL, RANK, and OPG genes does not make a significant genetic contribution to heel ultrasound measurements in a population of young Caucasian adults. Further studies replicating the results in independent populations are needed to support these initial findings.

Serum Osteoprotegerin Is a Potential Biomarker of Insulin Resistance in Chinese Postmenopausal Women with Prediabetes and Type 2 Diabetes

The aim of this study is to investigate the circulating OPG levels in postmenopausal women with diabetes and prediabetes and explore the relationships between serum OPG and insulin resistance. A total of 271 unrelated Chinese postmenopausal women were recruited in this study. The subjects were divided into type 2 diabetes mellitus (T2DM) group (n = 93), impaired glucose regulation (IGR) (n = 90), and normal glucose regulation group (NGR) (n = 88), according to different glucose regulation categories. Serum OPG levels were measured by enzyme-linked immunosorbent assay. The serum OPG concentration in NGR group, 151.00 ± 45.72 pg/mL, was significantly lower than that in IGR group (169.28 ± 64.91 pg/mL) (p = 0.031) and T2DM group (183.20 ± 56.53 pg/mL) (p < 0.01), respectively. In multiple linear regression analysis, HOMA-IR, age, 2hPG, AST, ALP, and eGFR were found to be independent predictors of OPG. Increased serum OPG levels (OR = 1.009, p = 0.006) may be a risk factor for insulin resistance. The present study suggests that OPG might be implicated in the pathogenesis of diabetes and is a potential biomarker of insulin resistance in subjects with diabetes and prediabetes.

FSH aggravates bone loss in ovariectomised rats with experimental periapical periodontitis

Periapical bone loss is one of the prominent pathological and clinical features of periapical periodontitis. Previous studies have demonstrated that follicle-stimulating hormone (FSH) could directly affect skeletal remodelling by stimulating the formation and the function of osteoclasts in vitro and in vivo. However, the effect of FSH on periapical bone loss remained to be fully elucidated. In the current study, a rat model was established in order to verify the effect of FSH in experimental periapical lesions. It was identified that FSH aggravated the bone loss of periapical lesions. In addition, RANKL-, TRAP-, TNF-α- and IL-1β-positive cells were increased significantly in FSH-treated groups, which indicated that the function of FSH in bone loss may be mediated through the increasing activity of osteoclasts and the increased secretion of inflammatory cytokines. The results of the current study suggested that FSH, independent of oestrogen, may aggravate periapical bone loss by FSH receptors, which may serve an important role in the immune and inflammatory response of the host to root canal and periradicular infection during menopause.

OPG and RANKL polymorphisms are associated with alcohol-induced osteonecrosis of the femoral head in the north area of China population in men

Alcohol-induced osteonecrosis of the femoral head (ONFH) is an important pathogenesis of nontraumatic ONFH. However, the mechanisms of the pathogenesis are still unknown. Osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa B ligand (RANKL) have been implicated in multiple functions including blocking osteoclast maturation, controlling vascular calcifications, and promoting tumor growth and metastasis. The purpose of this article was to explore the association between OPG and RANKL gene variants and alcohol-induced ONFH. Six hundred seventy male subjects (335 patients and 335 normal individuals) were enrolled in our study. We selected 24 single-nucleotide polymorphisms (SNPs) to evaluate the association between genetic susceptibility variants and alcohol-induced ONFH using the chi-square test and gene model analysis. Overall, the OPG SNPs (rs1032128 and rs11573828) were associated with the strongest increased risk of alcohol-induced ONFH in the recessive model (rs1032128: odds ratio [OR] 1.49, 95% confidence interval [CI] 1.00-2.22, P = 0.04 for G/A; rs11573828: OR 3.32, 95% CI 1.07-10.30, P = 0.03 for T/C). The RANKL SNP rs2200287 was also an increased risk factor (OR 3.65, 95% CI 1.53-8.47, P = 0.003 for T/C) in the recessive model. The rs11573856, rs3134056, and rs1564861 SNPs were considered protective factors for alcohol-induced ONFH. We concluded that OPG and RANKL polymorphisms were associated with the occurrence of alcohol-induced ONFH.