Genetic variation in the RANKL/RANK/OPG signaling pathway is associated with bone turnover and bone mineral density in men

Osteoporosis and Primary Biliary Cholangitis: A Trans-ethnic Mendelian Randomization Analysis

Osteoporosis is a major clinical problem in many autoimmune diseases, including primary biliary cholangitis (PBC), the most common autoimmune liver disease. Osteoporosis is a major cause of fracture and related mortality. However, it remains unclear whether PBC confers a causally risk-increasing effect on osteoporosis. Herein, we aimed to investigate the causal relationship between PBC and osteoporosis and whether the relationship is independent of potential confounders. We performed bidirectional Mendelian randomization (MR) analyses to investigate the association between PBC (8021 cases and 16,489 controls) and osteoporosis in Europeans (the UK Biobank and FinnGen Consortium: 12,787 cases and 726,996 controls). The direct effect of PBC on osteoporosis was estimated using multivariable MR analyses. An independent replication was conducted in East Asians (PBC: 2495 cases and 4283 controls; osteoporosis: 9794 cases and 168,932 controls). Trans-ethnic meta-analysis was performed by pooling the MR estimates of Europeans and East Asians. Inverse-variance weighted analyses revealed that genetic liability to PBC was associated with a higher risk of osteoporosis in Europeans (OR, 1.040; 95% CI, 1.016-1.064; P = 0.001). Furthermore, the causal effect of PBC on osteoporosis persisted after adjusting for BMI, calcium, lipidemic traits, and sex hormones. The causal relationship was further validated in the East Asians (OR, 1.059; 95% CI, 1.023-1.096; P = 0.001). Trans-ethnic meta-analysis confirmed that PBC conferred increased risk on osteoporosis (OR, 1.045; 95% CI, 1.025-1.067; P = 8.17 × 10-6). Our data supports a causal effect of PBC on osteoporosis, and the causality is independent of BMI, calcium, triglycerides, and several sex hormones.

Therapeutics of Charcot neuroarthropathy and pharmacological mechanisms: A bone metabolism perspective

Charcot neuroarthropathy (CN) is a chronic, destructive, and painless damage of the skeletal system that affects the life quality of patients. CN, with an unclear mechanism, is characterized with invasive destruction of bones and a serious abnormality of bone metabolism. Unfortunately, development of an effective prevention and treatment strategy for CN is still a great challenge. Of note, recent studies providing an insight into the molecular mechanisms of bone metabolism and homeostasis have propelled development of novel CN therapeutic strategies. Therefore, this review aims to shed light on the pathogenesis, diagnosis, and treatment of CN. In particular, we highlight the eminent role of the osteoprotegerin (OPG)-receptor activator of nuclear factor-κB (RANK)-RANK ligand (RANKL) system in the development of CN. Furthermore, we summarize and discuss the diagnostic biomarkers of CN as well as the potential pharmacological mechanisms of current treatment regimens from the perspective of bone metabolism. We believe that this review will enhance the current state of knowledge on the diagnosis, prevention, and therapeutic efficacy of CN.

Association between Osteoprotegerin rs2073618 polymorphism and peri-implantitis susceptibility: a meta-analysis

OBJECTIVES

Peri-implantitis was an inflammatory progress on the tissue around the implant. The Osteoprotegerin G1181C (rs2073618) polymorphism was reported to be related to the increased risk of the peri-implantitis, whereas another found no relationship. The present study was conducted to research the relationship between Osteoprotegerin rs2073618 polymorphism and peri-implantitis susceptibility.

MATERIALS AND METHODS

The meta-analysis was performed according to the Preferred Reporting Items for Systematic reviews. Electronic databases including PubMed, Web of science, Springer Link and Embase (updated to April 15, 2022) were retrieved. The cohort study, case-control study or cross-sectional study focusing on the Osteoprotegerin rs2073618 polymorphism and peri-implantitis were retrieved. The data included basic information of each study and the genotype and allele frequencies of the cases and controls.

RESULTS

Three studies were finally included, including 160 cases and 271 controls. Allelic model, homozygote model, recessive model, dominant model, and heterozygous model were established to assess the relationship between OPG rs2073618 polymorphism and peri-implantitis susceptibility. The Osteoprotegerin rs2073618 polymorphism was significantly associated with peri-implantitis in Recessive model and Homozygote model.

CONCLUSION

OPG rs2073618 polymorphism in Recessive model and Homozygote model was highly likely related to the risk of peri-implantitis. PROSPERO registration number: CRD42022320812.

Risk association of RANKL and OPG gene polymorphism with breast cancer to bone metastasis in Pashtun population of Khyber Pakhtunkhwa, Pakistan

Introduction

The receptor activator NF-κB ligand (RANKL) and Osteoprotegrin (OPG) single nucleotide polymorphisms (SNPs) have been associated with the risk of breast cancer to bone metastasis. This study was designed to investigate the association of RANKL and OPG gene polymorphisms with breast to bone metastasis in Pashtun population of Khyber Pakhtunkhwa, Pakistan.

Materials and methods

A total of 215 participants were enrolled containing 106 breast cancer patients, 58 breast to bone metastasis and 51 age and gender matched healthy controls. RANKL (rs9533156) and OPG (rs2073618, rs3102735) polymorphisms were genotyped in genomic DNA, using Tetra-ARMS PCR protocol. The results were analyzed among the three groups and P-value less then 0.05 were considered statistically significant.

Results

Our results displayed significant association of OPG (rs3102735) risk allele and corresponding genotypes in breast cancer vs healthy controls, bone metastasis vs healthy controls and breast cancer vs breast to bone metastasis as a disease risk. However, there was no association observed for OPG (rs2073618) risk allele and corresponding genotypes with the diseases risk. Similarly, RANKL (rs9533156) risk allele and corresponding genotypes in breast cancer vs healthy controls, bone metastasis vs healthy controls and breast cancer vs breast to bone metastasis exhibited significant association except for the risk allele carrying genotypes in breast to bone metastasis.

Conclusion

OPG (rs3102735) and RANKL (rs9533156) exhibited significant association with breast to bone metastasis while OPG (rs2073618) didn’t show significant association with breast to bone metastasis in Pashtun population of Pakistan. However, this study unlocks more questions to investigate the exact scenario of genetic predisposition of breast to bone metastasis.

An Overlooked Bone Metabolic Disorder: Cigarette Smoking-Induced Osteoporosis

Cigarette smoking (CS) leads to significant bone loss, which is recognized as an independent risk factor for osteoporosis. The number of smokers is continuously increasing due to the addictive nature of smoking. Therefore it is of great value to effectively prevent CS-induced osteoporosis. However, there are currently no effective interventions to specifically counteract CS-induced osteoporosis, owing to the fact that the specific mechanisms by which CS affects bone metabolism are still elusive. This review summarizes the latest research findings of important pathways between CS exposure and bone metabolism, with the aim of providing new targets and ideas for the prevention of CS-induced osteoporosis, as well as providing theoretical directions for further research in the future.

Serum levels of C-terminal telopeptide (CTX) are associated with muscle function in community-dwelling older adults

BACKGROUND

Markers of bone metabolism have been associated with muscle mass and function. Whether serum cross-linked C-terminal telopeptides of type I collagen (CTX) is also associated with these measures in older adults remains unknown.

METHODS

In community-dwelling older adults at high risk of falls and fractures, serum CTX (biochemical immunoassays) was used as the exposure, while appendicular lean mass (dual-energy x-ray absorptiometry) and muscle function (grip strength [hydraulic dynamometer], short physical performance battery [SPPB], gait speed, sit to stand, balance, Timed Up and Go [TUG]) were used as outcomes. Potential covariates including demographic, lifestyle and clinical factors were considered in statistical models. Areas under the ROC curves were calculated for significant outcomes.

RESULTS

299 older adults (median age: 79 years, IQR: 73, 84; 75.6% women) were included. In multivariable models, CTX was negatively associated with SPPB (β = 0.95, 95% CI: 0.92, 0.98) and balance (β = 0.92, 0.86, 0.99) scores, and positively associated with sit to stand (β = 1.02, 95% CI: 1.00, 1.05) and TUG (β = 1.03, 95% CI: 1.00, 1.05). Trend line for gait speed (β = 0.99, 95% CI: 0.98, 1.01) was in the hypothesized direction but did not reach significance. AUC curves showed low diagnostic power (<0.7) of CTX in identifying poor muscle function (SPPB: 0.63; sit to stand: 0.64; TUG: 0.61).

CONCLUSION

In older adults, higher CTX levels were associated with poorer lower-limb muscle function (but showed poor diagnostic power for these measures). These clinical data build on the biomedical link between bone and muscle.

The role of genetic factors and monocyte-to-osteoclast differentiation in the pathogenesis of Charcot neuroarthropathy

Charcot neuroarthropathy is a chronic, progressive condition of the skeletal system that affects some patients with diabetic neuropathy. It results in progressive destruction of bones of the foot and disorganisation of pedal joints and ligaments. Effective prevention and treatment for Charcot neuroarthropathy remain a challenge. Currently, there are no reliable repeatable markers to identify patients with diabetes who are at higher risk of developing Charcot neuroarthropathy. The pathogenesis underlying the development of Charcot neuroarthropathy also remains unclear. In this review, we provide an overview of the history, prevalence, symptoms, risk factors, diagnostics and treatment of Charcot neuroarthropathy. We also discuss the potential for OPG and RANKL gene variants to act as predictive markers for the development of Charcot neuroarthropathy. Finally, we summarise the latest research on the role of monocyte-to-osteoclast differentiation in the development of acute Charcot neuroarthropathy.

Keratinocytes-derived exosomal miRNA regulates osteoclast differentiation in middle ear cholesteatoma

The occurrence and development of osteoclasts can directly affect the severity of bone destruction in middle ear cholesteatoma. At the same time, cell communication between keratinocytes and fibroblasts can stimulate osteoclast differentiation. However, the molecular mechanism of osteoclast differentiation in cholesteatoma is still poorly understood. In this study, we try to isolate the exosomes of keratinocytes from patients with middle ear cholesteatoma, and explore the effects of keratinocyte-derived exosomes (Ker-Exo) on osteoclast differentiation by co-culturing Ker-Exo with fibroblasts and osteoclast precursor cells. As a result, we confirmed that Ker-Exo primed fibroblasts can up-regulate the expression of RANKL and promote osteoclast differentiation. We revealed that the effect of Ker-Exo depened on its miRNA-17 conponent. Analysis confirmed that miRNA-17 was down-regulated in Ker-Exo, and they can increase RANKL level in fibroblasts, thus promoting the differentiation of osteoclasts. In conclusions, we provide evidence that exosomes miRNA-17 secreted by keratinocytes in patients with middle ear cholesteatoma can up-regulate the expression of RANKL in fibroblasts and induce osteoclast differentiation.

High risk of lumbar spine osteoporosis with the RANK rs3018362 polymorphism

Osteoporosis is characterized by reduced bone mineral density (BMD) and quality, increasing the risk of fractures. A large number of genes involved in bone metabolism have been implicated in the genesis of osteoporosis; these include RANK and RANKL. Polymorphisms of these genes have been implicated in osteoporosis. The aim of this study was to determine the association of the RANK rs3018362 and RANKL rs12585014 polymorphisms with risk of osteoporosis. Four hundred Mexican women aged 40 years old or above were genotyped by real-time PCR and several demographic and risk factors were explored. The GA and AA genotypes of the rs3018362 polymorphism were associated with a high risk of osteoporosis in the dominant model (p=.0062; OR = 2.16, 95% CI: 1.24-3.78). In summary, the rs3018362 polymorphism in the RANK gene seems to be associated with osteoporosis of the lumbar spine while the RANKL rs12585014 is not, although more studies are needed to confirm these results.

Genetic polymorphisms and their influence on therapeutic response to alendronate-a pilot study

Introduction: Osteoporosis has a strong genetic contribution, and several genes have been shown to influence bone mineral density. Variants in the human genome are considered important causes of differences in drug responses observed in clinical practice. In terms of bone mineral density, about 26–53% of patients do not respond to amino-bisphosphonate therapies, of which alendronate is the most widely used. Material and method: The current study is prospective, observational, analytical, longitudinal and cohort type. It included 25 postmenopausal women treated with alendronate for 1 year. Bone mineral density at lumbar spine and proximal femur was measured and bone turnover markers (C-terminal telopeptide of type I collagen and procollagen 1N-terminal propeptide) were evaluated at 0 and 12 months of treatment. Six single nucleotide polymorphisms in osteoporosis-candidate genes were genotyped (FDPS rs2297480, LRP5 rs3736228, SOST rs1234612, VKORC1 rs9934438, GGPS1 rs10925503 and RANKL rs2277439). Treatment response was evaluated by percentage changes in bone mineral density and bone turnover markers. Results: The heterozygous CT of FDPS rs2297480 showed lower increases in BMD values in the lumbar spine region and the homozygous CC of the GGPS1 rs10925503 showed lower increases in terms of BMD at the total hip region. No association was found for LRP5 rs3736228, SOST rs1234612, VKORC1 rs9934438 and RANKL rs2277439. Conclusions: Romanian postmenopausal women with osteoporosis carrying the CT genotype of FDPS rs2297480 or the CC genotype of GGPS1 rs10925503 could have an unsatisfactory response to alendronate treatment. Key words: osteoporosis; genetic polymorphism; alendronate; bone mineral density; bone turnover markers,

Genetic variants in the PLS3 gene are associated with osteoporotic fractures in postmenopausal Chinese women

Plastin 3 (PLS3) has been identified as a candidate gene for bone fragility in the Rotterdam study (RS) population. So far, however, whether PLS3 polymorphisms are genetic risk factors for osteoporosis in Asian population remains unclear. In order to investigate the association between genetic variants in PLS3 and the risk of fragility fracture and/or bone mineral density (BMD) in postmenopausal Chinese women, we conducted a case-control association study. A total of 1083 postmenopausal patients with osteoporotic fractures and 2578 unrelated non-fracture controls in Shanghai were enrolled. Seven SNPs, including six tagSNPs in PLS3 and one identified genetic risk factor (rs140121121) for osteoporosis in the RS population, were genotyped in all the participants. BMD at lumbar spine and hip sites were measured in 2578 controls. Association between SNPs and the risk of osteoporotic fractures and/or BMD were analyzed. The GC genotype of rs757124 and AC genotype of rs10521693 were associated with lumbar vertebral fracture (P = 0.020 and 0.046, respectively). The association between tagSNPs and BMD were analyzed only in 2546 controls to avoid biased conclusion. rs757124 was significantly associated with BMD at lumbar spine and hip sites. GG genotype had the highest BMD at lumbar spine (L1-4), while CC genotype had the highest BMD at hip sites. Our results suggest that polymorphisms in PLS3 are genetic loci for osteoporosis in postmenopausal Chinese women.

Regulation of Hedgehog signaling Offers A Novel Perspective for Bone Homeostasis Disorder Treatment

The hedgehog (HH) signaling pathway is central to the regulation of bone development and homeostasis. HH signaling is not only involved in osteoblast differentiation from bone marrow mesenchymal stem cells (BM-MSCs), but also acts upstream within osteoblasts via the OPG/RANK/RANKL axis to control the expression of RANKL. HH signaling has been found to up-regulate parathyroid hormone related protein (PTHrP) expression in osteoblasts, which in turn activates its downstream targets nuclear factor of activated T cells (NFAT) and cAMP responsive element binding protein (CREB), and as a result CREB and NFAT cooperatively increase RANKL expression and osteoclastogenesis. Osteoblasts must remain in balance with osteoclasts in order to avoid excessive bone formation or resorption, thereby maintaining bone homeostasis. This review systemically summarizes the mechanisms whereby HH signaling induces osteoblast development and controls RANKL expression through PTHrP in osteoblasts. Proper targeting of HH signaling may offer a therapeutic option for treating bone homeostasis disorders.

The RANKL rs12585014 polymorphism is associated with age at menarche in postmenopausal women with hip fracture

The RANK/RANKL/OPG signaling is important in the regulation of bone turnover. The aim of the present work was to analyze the rs3018362 and rs12585014 polymorphisms in the RANK and RANKL genes, as well as risk factors in postmenopausal women. Women with hip fracture, with femoral neck osteoporosis and controls (n = 646) were recruited. From these, 303 women who fulfill the inclusion criteria were genotyped using real-time PCR with TaqMan probes. There were no associations of the rs3018362 and rs12585014 with osteoporosis or fracture. When women were divided by age at menarche, the rs12585014 GG genotype was strongly associated with age at menarche >13 years [p = .00774, OR = 6.429 (1.907-21.103)] in women with hip fracture. Significant differences in risk factors such as body mass index, age at menopause, use of estrogens, the presence of hypertension, and diabetes mellitus were found. Carrying the GG genotype of rs12585014 entails a higher risk of having menarche later (>13 years), which could involves a greater risk of fractures. The rs3018362 and rs12585014 do not seem to be associated with hip osteoporosis or hip fracture in Mexican women.

The genetic association between osteoprotegerin (OPG) gene polymorphisms and bone mineral density (BMD) in postmenopausal women: A meta-analysis

BACKGROUND

Osteoporosis is a common skeletal disorder in eldest people, especially in postmenopausal women. The osteoprotegerin (OPG) gene has been reported to be associated with the BMD and pathogenesis of osteoporosis. However, the results were inconsistent and inconclusive in previous studies.

METHODS

A meta-analysis was performed to investigate the effect of four common OPG gene polymorphisms (A163G, G1181C, T245G, and T950C) on BMD in postmenopausal women.

RESULTS

A total of 23 eligible studies with 12,973 postmenopausal women were enrolled in present study. Individuals who with AA genotype of A163G were found to have slightly higher femoral hip (P = .03, SMD = 0.49, [95% CI] = [0.06, 0.91]) and total hip BMD (P = .002, SMD = -0.25, [95% CI] = [-0.42, -0.09]) than those with AG genotype. Subjects with GG genotype of G1181C was found to have lower BMD than those with CC or GC genotypes in lumbar spine (GG vs GC: P = .0002, SMD = -0.85, [95% CI] = [-1.29, -0.41]; GG vs CC: P = .02, SMD = -0.21, [-0.39, -0.03]) and total hip BMD (GG vs GC: P = .002, SMD = -0.25, [95% CI] = [-0.42, -0.09]; GG vs CC: P = .01, SMD = -0.15, [95% CI] = [-0.26, -0.03]). In addition, the subjects with GC genotype of G1181C was detected to have lower BMD than those with CC genotype in lumbar spine BMD (P < .05). Furthermore, individuals with TT genotype of T950C were shown to have significant lower lumbar spine BMD compared with those with genotype CC in Caucasian (P < .05). The lumbar spine BMD was lower for subjects with TC genotype of T950C than those with CC genotype in both Caucasian and Asian populations (P < .05). In contrast to A163G, G1181C, and T950G, no association was detected between T245G polymorphism and BMD (P > .05).

CONCLUSION

The present meta-analysis demonstrated the OPG A163G, G1181C, and T950G, but not T245G, might influence the BMD in postmenopausal women.

Gene variants of osteoprotegerin, estrogen-, calcitonin- and vitamin D-receptor genes and serum markers of bone metabolism in patients with Gaucher disease type 1

Purpose

Osteopathy/osteoporosis in Gaucher disease type 1 (GD1) shows variable responses to enzyme replacement therapy (ERT); the pathogenesis is incompletely understood. We aimed to investigate the effects of several gene variants on bone mineral density (BMD) and serum markers of bone metabolism in GD1.

Patients and methods

Fifty adult Caucasian patients with GD1/117 controls were genotyped for gene variants in the osteoprotegerin (TNFRSF11B; OPG), estrogen receptor alpha, calcitonin receptor (CALCR), and vitamin D receptor (VDR) genes. In patients and 50 matched healthy controls, we assessed clinical data, serum markers of bone metabolism, and subclinical inflammation. BMD was measured for the first time before/during ERT (median 6.7 years).

Results

Forty-two percent of patients were splenectomized. ERT led to variable improvements in BMD. Distribution of gene variants was comparable between patients/controls. The AA genotype (c.1024+283G>A gene variant; VDR gene) was associated with lower Z scores before ERT vs GA (P=0.033), was encountered in 82.3% of patients with osteoporosis and was more frequent in patients with pathological fractures. Z score increases during ERT were higher in patients with the CC genotype (c.9C>G variant, TNFRSF11B; OPG gene; P=0.003) compared with GC (P=0.003). The CC genotype (c.1340T>C variant, CALCR gene) was associated with higher Z scores before ERT than the TT genotype (P=0.041) and was absent in osteoporosis. Osteocalcin and OPG were lower in patients vs controls; beta crosslaps, interleukin-6, and ferritin were higher.

Conclusions

We suggest for the first time a protective role against osteoporosis in GD1 patients for the CC genotype of the c.9C>G gene variant in the TNFRSFB11 (OPG) gene and for the CC genotype of the c.1340T>C gene variant (CALCR gene), while the AA genotype of the c.1024+283G>A gene variant in the VDR gene appears as a risk factor for lower BMDs. Serum markers suggest decreased osteosynthesis, reduced inhibition of osteoclast activation, increased bone resorption, and subclinical inflammation during ERT.

Applying a weight of evidence approach to the evaluation of developmental toxicity of biopharmaceuticals

Toxicity studies in pregnant animals are not always necessary for assessing the human risk of developmental toxicity of biopharmaceuticals. The growing experience and information on target biology and molecule-specific pharmacokinetics present a powerful approach to accurately anticipate effects of target engagement by biopharmaceuticals using a weight of evidence approach. The weight of evidence assessment should include all available data including target biology, pharmacokinetics, class effects, genetically modified animals, human mutations, and a thorough literature review. When assimilated, this weight of evidence evaluation may be sufficient to inform risk for specific clinical indications and patient populations. While under current guidance this approach is only applicable for drugs and biologics for oncology, the authors would like to suggest that this approach may also be appropriate for other disease indications. When there is an unacceptable level of uncertainty and a toxicity study in pregnant animals could impact human risk assessment, then such studies should be considered. Determination of appropriate nonclinical species for developmental toxicity studies to inform human risk should consider species-specific limitations, reproductive physiology, and pharmacology of the biopharmaceutical. This paper will provide considerations and examples of the weight of evidence approach to evaluating the human risk of developmental toxicity of biopharmaceuticals.

SNPs in the vicinity of P2X7R, RANK/RANKL/OPG and Wnt signalling pathways and their association with bone phenotypes in academy footballers

CONTEXT

Genotype plays an important role in influencing bone phenotypes, such as bone mineral density, but the role of genotype in determining responses of bone to exercise has yet to be elucidated.

OBJECTIVE

To determine whether 10 SNPs associated with genes in the vicinity of P2X7R, RANK/RANKL/OPG and Wnt Signalling Pathways are associated with bone phenotypes in elite academy footballers (Soccer players) and to determine whether these genotypes are associated with training induced changes in bone. Design, participants, and methods: 99 elite academy footballers volunteered to participate. Peripheral computed tomography of the tibia (4%, 14%, 38% and 66% sites) was performed immediately before and 12 weeks after an increase in football training volume. Genotypes were determined using proprietary fluorescence-based competitive allele-specific PCR assays.

RESULTS

No significant genotype by time interactions were shown for any of the SNPs analysed (P > .05). A main effect of genotype was shown. SOST SNP rs1877632 (trabecular density), P2X7R SNPs rs1718119 (cortical thickness and CSA), rs3751143 (SSI, CSA, cortical CSA and periosteal circumference) RANK/RANKL/OPG SNPs rs9594738 (periosteal circumference), rs1021188 (cortical thickness and CSA) and rs9594759 (cortical density) were associated with bone phenotypes (P < .05).

CONCLUSIONS

No association was shown between P2X7R, RANK/RANKL/OPG and Wnt Signalling SNPs and a change in bone phenotypes following 12 weeks of increased training volume in elite academy footballers. However, SNPs were associated with bone phenotypes pre training. These data highlight the complexity of the interaction between SNPs in the vicinity of the RANK/RANKL/OPG, P2X7R and Wnt metabolic regulatory pathways and bone phenotypes in elite academy footballers.

Icariin Enhances Bone Repair in Rabbits with Bone Infection during Post-infection Treatment and Prevents Inhibition of Osteoblasts by Vancomycin

Vancomycin is an effective antibiotic for treatment of bone infection caused by Staphylococcus aureus, however, a high local concentration of vancomycin might induce a delay in bone union. Icariin has been reported to suppress osteoclastogenes and promote osteogenesis. Our study aimed to investigate the effect of icariin on bone repair after anti-infection treatment in vivo and to explore the resisting effect of icariin on rat calvarial osteoblasts (ROBs) inhibited with high doses of vancomycin. Rabbits with bone infection of S. aureus were treated with implanted vancomycin-calcium sulfate (VCS) and icariin at 10.86 mg/kg/day for consecutive 8 weeks. Micro-CT, morphology, blood biochemistry were evaluated. In addition, ROBs were treated with vancomycin and icariin at different doses. Cell proliferation and differentiation capabilities, BMP2, Runx2, OPG, RANKL mRNA levels and protein expression were assessed. The results indicated that high dose of vancomycin significantly decreased bone mass and inhibited osteocalcin secretion; icariin increased these indicators compared with the single vancomycin treatment. Over 0.1 mg/mL of vancomycin inhibited the proliferation and differentiation of ROBs, while icariin resisted the inhibition of vancomycin by regulating cell cycle and promoting the Alkaline phosphatase (ALP) activity. Moreover, icariin promote bone formation by up-regulating BMP2/Runx2 and OPG/RANKL pathways. Icariin exhibited osteoplastic properties on osteoblasts that had been inhibited with high doses of vancomycin. Therefore, icariin is helpful for post-infection treatment of bone infection.

MicroRNA-34a alleviates steroid-induced avascular necrosis of femoral head by targeting Tgif2 through OPG/RANK/RANKL signaling pathway

The study aims to investigate the effect of microRNA-34a (miR-34a) targeting Tgif2 on steroid-induced avascular necrosis of femoral head (SANFH) by regulating OPG/RANK/RANKL signaling pathway. SD rats were divided into normal control and model (RNAKL rat models) groups. The model group was further assigned into model control, negative control, miR-34a mimics and miR-34a inhibitors groups. QRT-PCR was applied to detect miR-34a, Tgif2, OPG, RANK and RNAKL mRNA expressions. Femoral head tissues were collected for Micro-CT scanning and HE staining. QRT-PCR and Western blotting were used to detect expressions of miR-34a, Tgif2, OPG, RANK, RANKL and Runx2, OPN and OC in bone tissues. Dual-luciferase reporter gene assay was used to testify the target relationship between miR-34a and Tgif2. Compared with the normal control group, the model group showed increased Tgif2, RANK and RANKL mRNA expressions, but decreased miR-34a and OPG mRNA expressions. Tgif2 mRNA expression was negatively correlated with miR-34a and OPG mRNA expressions. Micro-CT showed cystic degeneration of femoral head, with decreased bone volume/total volume (BV/TV), bone surface area/bone volume and trabecular number in the model control group compared with the normal control group. Compared with the model control group, the miR-34a mimics group showed increased BV/TV and trabecular thickness and Runx2, OPN and OC expressions, while the parameters decreased in the miR-34a inhibitors group. Compared with the normal control group, the other groups showed increased Tgif2, RANK and RANKL expressions but decreased miR-34a and OPG expressions. Compared with the model control group, Tgif2, RANK and RANKL expressions decreased and miR-34a and OPG expressions increased in the miR-34a mimics group, while the miR-34a inhibitors group had a reverse trend in contrast to the miR-34a mimics group. Tgif2 is a target gene of miR-34a. In conclusion, miR-34a can alleviate SANFH through targeting Tgif2 and further regulating OPG/RANK/RANKL signaling pathway. Impact statement miR-34a can alleviate SANFH through targeting Tgif2 and further regulating OPG/RANK/RANKL signaling pathway, which can be used as a new theoretical basis for SANFH treatment.

Bone Mineral Density Is Positively Related to Carotid Intima-Media Thickness: Findings From a Population-Based Study in Adolescents and Premenopausal Women

Osteoporosis and cardiovascular disease (CVD) are both common causes of morbidity and mortality. Previous studies, mainly of people older than 60 years, suggest a relationship between these conditions. Our aim was to determine the association between bone characteristics and CVD markers in younger and middle-aged individuals. Women (n = 3366) and their adolescent offspring (n = 4368) from the UK population-based cohort study, Avon Longitudinal Study of Parents and Children (ALSPAC), were investigated. We measured total body (TB) and hip bone mineral density (BMD), TB bone area (BA) and bone mineral content (BMC) by dual-energy X-ray absorptiometry (DXA), and carotid intima-media thickness (cIMT) by high-resolution ultrasound. Arterial distensibility was calculated as the difference between systolic and diastolic arterial diameters. Linear regression determined associations between bone exposures and cIMT (in adolescents) and both cIMT and arterial distensibility (in women), generating partial correlation coefficients. Mean (SD) age of women was 48 (4.2) years, body mass index (BMI) was 26.2 (5.0) kg/m² , and 71% were premenopausal. In confounder-adjusted analyses (age, height, lean mass, fat mass, menopause, smoking, estrogen replacement, calcium/vitamin D supplementation, and education) TB and hip BMD were both positively associated with cIMT (0.071 [0.030, 0.112], p = 0.001; 0.063 [0.025, 0.101], p = 0.001, respectively). Femoral neck BMD and TB BMD, BMC, and BA were positively associated with arterial distensibility. Mean (SD) age of adolescents was 17 (0.4) years, BMI was 23 (4.1) kg/m² , and 44.5% were male. Total hip and TB measurements were positively associated with cIMT, with similar magnitudes of association to those found in their mothers. In contrast to most published findings, we identified weak positive associations between BMD and cIMT in predominantly premenopausal women and their adolescent offspring. We found greater femoral neck BMD and TB DXA measurements to be associated with reduced arterial stiffness. Rather than a relationship with preclinical atherosclerosis, in these relatively young populations, we speculate our associations between BMD, cIMT, and arterial distensibility may reflect a shared relationship between bone and vascular growth and development. © 2016 American Society for Bone and Mineral Research.

Osteoprotegerin Gene (OPG) Polymorphisms Associated with Peri-implantitis Susceptibility in a Chinese Han Population

Background

The aim of this study was to investigate the association between T950C (rs2073617) and G1181C (rs2073618) polymorphisms of the osteoprotegerin gene (OPG) and the susceptibility of peri-implantitis in the Chinese Han population.

Material/Methods

110 patients with peri-implantitis and 116 healthy persons from the Chinese Han population were included in this study using a case-control design; rs2073617 and rs2073618 in OPG were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The linkage disequilibrium (LD) and haplotype analysis were performed with Haploview software. Hardy-Weinberg equilibrium (HWE) was assessed in the control group based on the genotype distributions of OPG polymorphisms. The genotype, allele, and haplotype distribution differences between the case and control groups were analyzed by chi-square test, and the relative risk of PD was expressed by odds ratio (OR) and 95% confidence interval (CI).

Results

The study results showed that people carrying the CC genotype of rs2073618 were more likely to have peri-implantitis than GG genotype carriers (OR=2.18, 95% CI=1.03–4.62, p=0.04). In addition, patients with the C allele had 1.47 times the risk of suffering from peri-implantitis (OR=1.47, 95% CI=1.01–2.13, p=0.04), but not rs2073617 polymorphism. The G-C haplotype frequency of rs2073618-rs2073617 in OPG was significantly correlated to the increased susceptibility of peri-implantitis (OR=2.27, 95% CI=1.20–4.30).

Conclusions

OPG rs2073618 polymorphism may be related to the risk of peri-implantitis, but not rs2073617. Moreover, haplotype is also a non-ignorable risk factor.

Transcriptional regulation of the human TNFSF11 gene in T cells via a cell type-selective set of distal enhancers

In addition to osteoblast lineage cells, the TNF-like factor receptor activator of NF-κB ligand (RANKL) is expressed in both B and T cells and may play a role in bone resorption. Rankl gene (Tnfsf11) expression in mouse T cells is mediated through multiple distal elements marked by increased transcription factor occupancy, histone tail acetylation, and RNA polymerase II recruitment. Little is known, however, of the regulation of human TNFSF11 in T cells. Accordingly, we examined the consequence of T cell activation on the expression of this factor both in Jurkat cells and in primary human T cells. We then explored the mechanism of this regulation by scanning over 400 kb of DNA surrounding the TNFSF11 locus for regulatory enhancers using ChIP-chip analysis. Histone H3/H4 acetylation enrichment identified putative regulatory regions located between -170 and -220 kb upstream of the human TNFSF11 TSS that we designated the human T cell control region (hTCCR). This region showed high sequence conservation with the mouse TCCR. Inhibition of MEK1/2 by U0126 resulted in decreased RANKL expression suggesting that stimulation through MEK1/2 was a prerequisite. ChIP-chip analysis also revealed that c-FOS was recruited to the hTCCR as well. Importantly, both the human TNFSF11 D5a/b (RLD5a/b) enhancer and segments of the hTCCR mediated robust inducible reporter activity following TCR activation. Finally, SNPs implicated in diseases characterized by dysregulated BMD co-localized to the hTCCR region. We conclude that the hTCCR region contains a cell-selective set of enhancers that plays an integral role in the transcriptional regulation of the TNFSF11 gene in human T cells.

RANKL and OPG Polymorphisms Are Associated with Aromatase Inhibitor-Related Musculoskeletal Adverse Events in Chinese Han Breast Cancer Patients

Background

Breast cancer patients treated with aromatase inhibitors (AIs) may experience musculoskeletal adverse events (MS-AEs). Several studies have confirmed that the RANKL/RANK/OPG signaling pathway plays a dominant role in bone health. Therefore, this study aimed to analyze the relationship between the serum levels of RANKL, OPG and their SNPs (single nucleotide polymorphisms) with AI-related MS-AEs.

Methodology and Principal Findings

Patients with early stage, hormone-sensitive breast cancer who were receiving AI therapy were enrolled. We included 208 cases with AI-related MS-AEs and 212 without (controls). The levels of estradiol, bone-turnover markers, multiple inflammatory cytokines, RANKL,OPG and lumbar spine BMD were measured, and questionnaires were completed. We analyzed 29 SNPs of RANKL, RANK and OPG using Sequenom MassARRAY assays and PCR-based TaqMan assays. The levels of bone-turnover markers and RANKL and the ratio of RANKL/OPG were higher in patients with AI-related MS-AEs than controls (all p < 0.05). A genetic assay showed that the RANKL SNP rs7984870 and OPG SNP rs2073618 were associated with AI-related MS-AEs. In patients with AI-related MS-AEs, rs7984870 CC and rs2073618 CC were risk genotypes. Carriers of the rs7984870 CC genotype were more likely to have a higher RANKL level and RANKL/OPG ratio than carriers of the GG genotype, and carriers of the rs2073618 CC genotype were more likely to have a lower OPG level and a higher RANKL/OPG ratio than carriers of the GG genotype (all p < 0.05). Moreover, risk genotypes were associated with higher levels of serum CTX and PINP and a lower lumbar spine BMD (all p < 0.05).

Conclusions and Significance

In conclusion, the RANKL and OPG risk genotypes synergize to negatively impact bone health and predispose breast cancer patients to AI-related MS-AEs.

The association between RANKL and Osteoprotegerin gene polymorphisms with breast cancer

Breast cancer is the most common cause of cancer death among women (522,000 deaths in 2012). Imbalance between RANKL and OPG is observed in many cancers, including breast cancer. Consequently, SNPs in the genes of RANKL and OPG may be involved in breast cancer development. This study included 276 subjects. Group I (n = 100) healthy females as a control group, group II (n = 96) breast cancer patients without bone metastases, and group III (n = 80) breast cancer patients with bone metastases. RANKL rs9533156, OPG rs2073618, and OPG rs2073617 SNPs and their serum protein levels were studied for a possible association with breast cancer development. The allele frequency [(OR: 4.832 CI 2.18-10.71, P = 0.001) and genotype distribution (P = 0.001)] of OPG SNP rs2073618 showed a highly significant difference between breast cancer patients and healthy controls. The allele C is more common in breast cancer patients. The allele frequency [(OR: 0.451 CI 0.232-0.879, P = 0.018) and genotype distribution (P = 0.003)] of RANKL SNP rs9533156 differed significantly between breast cancer patients and healthy controls. The allele T is more common in breast cancer patients. The allele frequency [(OR: 0.36 CI 0.184-0.705, P = 0.002) and genotype distribution (P = 0.011)] of OPG SNP rs2073617 differed significantly between breast cancer patients and healthy controls. The allele T is more common in breast cancer patients. The C allele of OPG SNP rs2073618 may be associated with breast cancer development. No association was found between any of the SNPs and the serum protein levels of RANKL and OPG.

RANK/RANKL/OPG pathway: genetic associations with stress fracture period prevalence in elite athletes

CONTEXT

The RANK/RANKL/OPG signalling pathway is important in the regulation of bone turnover, with single nucleotide polymorphisms (SNPs) in genes within this pathway associated with bone phenotypic adaptations.

OBJECTIVE

To determine whether four SNPs associated with genes in the RANK/RANKL/OPG signalling pathway were associated with stress fracture injury in elite athletes.

DESIGN, PARTICIPANTS, AND METHODS

Radiologically confirmed stress fracture history was reported in 518 elite athletes, forming the Stress Fracture Elite Athlete (SFEA) cohort. Data were analysed for the whole group and were sub-stratified into male and cases of multiple stress fracture groups. Genotypes were determined using proprietary fluorescence-based competitive allele-specific PCR assays.

RESULTS

SNPs rs3018362 (RANK) and rs1021188 (RANKL) were associated with stress fracture injury (P<0.05). 8.1% of the stress fracture group and 2.8% of the non-stress fracture group were homozygote for the rare allele of rs1021188. Allele frequency, heterozygotes and homozygotes for the rare allele of rs3018362 were associated with stress fracture period prevalence (P<0.05). Analysis of the male only group showed 8.2% of rs1021188 rare allele homozygotes had suffered a stress fracture whilst 2.5% of the non-stress fracture group were homozygous. In cases of multiple stress fractures, homozygotes for the rare allele of rs1021188 and individuals possessing at least one copy of the rare allele of rs4355801 (OPG) were shown to be associated with stress fracture injury (P<0.05).

CONCLUSIONS

The data support an association between SNPs in the RANK/RANKL/OPG signalling pathway and the development of stress fracture injury. The association of rs3018362 (RANK) and rs1021188 (RANKL) with stress fracture injury susceptibility supports their role in the maintenance of bone health and offers potential targets for therapeutic interventions.

Androgens and estrogens in skeletal sexual dimorphism

Bone is an endocrine tissue expressing androgen and estrogen receptors as well as steroid metabolizing enzymes. The bioactivity of circulating sex steroids is modulated by sex hormone-binding globulin and local conversion in bone tissue, for example, from testosterone (T) to estradiol (E2) by aromatase, or to dihydrotestosterone by 5α-reductase enzymes. Our understanding of the structural basis for gender differences in bone strength has advanced considerably over recent years due to increasing use of (high resolution) peripheral computed tomography. These microarchitectural insights form the basis to understand sex steroid influences on male peak bone mass and turnover in cortical vs trabecular bone. Recent studies using Cre/LoxP technology have further refined our mechanistic insights from global knockout mice into the direct contributions of sex steroids and their respective nuclear receptors in osteoblasts, osteoclasts, osteocytes, and other cells to male osteoporosis. At the same time, these studies have reinforced the notion that androgen and estrogen deficiency have both direct and pleiotropic effects via interaction with, for example, insulin-like growth factor 1, inflammation, oxidative stress, central nervous system control of bone metabolism, adaptation to mechanical loading, etc., This review will summarize recent advances on these issues in the field of sex steroid actions in male bone homeostasis.

RANK rs1805034 T>C polymorphism is associated with susceptibility of esophageal cancer in a Chinese population

Esophageal cancer remains the sixth leading cause of cancer associated death and eighth most common cancer worldwide. Genetic factors, such as single nucleotide polymorphisms (SNPs), may contribute to the carcinogenesis of esophageal cancer. Here, we conducted a hospital based case-control study to evaluate the genetic susceptibility of functional SNPs on the development of esophageal cancer. A total of 629 esophageal squamous cell carcinoma (ESCC) cases and 686 controls were enrolled for this study. The OPG rs3102735 T>C, rs2073618 G>C, RANK rs1805034 T>C, RANKL rs9533156 T>C and rs2277438 A>G were determined by ligation detection reaction method. Our findings suggested that RANK rs1805034 T>C is associated with the susceptibility of ESCC, which is more evident in male and elder (≥63) patients. Our study provides the first evidence that functional polymorphisms RANK rs1805034 T>C may be an indicator for individual susceptibility to ESCC. However, further larger studies among different ethnic populations are warranted to verify our conclusion.

HLA alleles association with changes in bone mineral density in HIV-1-infected adults changing treatment to tenofovir-emtricitabine or abacavir-lamivudine

Background

There are limited data regarding the influence of human leukocyte antigen (HLA) polymorphisms on reduced bone mineral density (BMD). We investigated the relationship between HLA supertypes and BMD in HIV-infected adults changing their existing treatment to tenofovir-emtricitabine (TDF-FTC) or abacavir-lamivudine (ABC-3TC) in the STEAL study.

Methods

Lumbar spine and right hip BMD were measured by Dual-energy X-ray absorptiometry (DXA). HLA genotypes at the 2-digit level were classified into class I and II supertypes. Student's t-tests were used to test the association between HLA supertypes and changes in hip and spine BMD over 96 weeks for the whole cohort and stratified by randomised groups. The relationship between HLA supertypes and BMD was also assessed in the subgroup of participants that were naïve to both ABC and TDF at study entry.

Results

Class II supertypes were mainly associated with hip BMD change. Overall, compared to participants not carrying HLA-DQ3, participants expressing DQ3 had less bone loss over 96 weeks at both the hip and spine (hip: 0.003 vs. −0.006 g/cm², 95%CI 0.002 to 0.017, p = 0.016; spine: 0.006 vs. −0.006 g/cm², 95%CI 0.001 to 0.023, p = 0.041). In participants that were naïve to both ABC and TDF at baseline and randomised to TDF-FTC, DQ3 was significantly associated with less bone loss compared with those not carrying DQ3 (hip: 0.001 vs. −0.032 g/cm²; diff 0.033; 95%CI 0.017 to 0.049; p<0.001; spine: 0.007 vs. −0.023 g/cm²; diff 0.035; 95%CI 0.014 to 0.056; p = 0.001).

Conclusions

In this cohort of HIV-infected adults, there was an association between bone status and HLA supertypes, particularly HLA-DQ3.

Trial Registration

Clinicaltrials.gov NCT00192634

Association of ESR1 and C6orf97 gene polymorphism with osteoporosis in postmenopausal women

The estrogen receptor 1 (ESR1) and Chromosome 6 Open Reading Frame 97 (C6orf97) gene polymorphisms were earlier reported to be associated with osteoporosis in the European cohort. The aim of this study was to investigate the association of four single nucleotide polymorphisms (SNP) with bone mineral density (BMD), fracture, vertebral fracture, bone turnover or 25-hydroxyvitamin D [25(OH)D] in 1,753 randomly selected postmenopausal women in China. Vertebral fracture, BMD of lumbar spine (2-4), femoral neck and total hip were measured respectively. Serum N-terminal procollagen of type 1 collagen (P1NP), β-isomerized type I collagen C-telopeptide breakdown products (β-CTX) and 25(OH)D3 were also determined. Binary logistic regression revealed significant associations between fracture risk with rs1999805 (P=0.041, OR 1.633, 95%CI 1.020-2.616) and rs6929137 (P=0.005, OR 1.932, 95%CI 1.226-3.045) in recessive model. Significant association was also observed between vertebral fracture risk and rs1038304 (P=0.039, OR 0.549, 95%CI 0.311-0.969) in recessive model. Liner regression analyses showed that only the CC group of rs4870044 was significantly associated with total hip in dominant model (P=0.034). Our findings suggest that ESR1 and C6orf97 gene polymorphism is associated with fracture and vertebral fracture risk in Chinese postmenopausal women.

Genome-wide approaches for identifying genetic risk factors for osteoporosis

Osteoporosis, the most common type of bone disease worldwide, is clinically characterized by low bone mineral density (BMD) and increased susceptibility to fracture. Multiple genetic and environmental factors and gene-environment interactions have been implicated in its pathogenesis. Osteoporosis has strong genetic determination, with the heritability of BMD estimated to be as high as 60%. More than 80 genes or genetic variants have been implicated in risk of osteoporosis by hypothesis-free genome-wide studies. However, these genes or genetic variants can only explain a small portion of BMD variation, suggesting that many other genes or genetic variants underlying osteoporosis risk await discovery. Here, we review recent progress in genome-wide studies of osteoporosis and discuss their implications for medicine and the major challenges in the field.

Association of genetic polymorphisms of RANK, RANKL and OPG with bone mineral density in Chinese peri- and postmenopausal women

OBJECTIVES

To explore the influence of 14 single nucleotide polymorphisms (SNPs) in receptor activator of nuclear factor-kappa B (RANK), RANK ligand (RANKL) and osteoprotegerin (OPG) on bone mineral density (BMD) in a Chinese female population.

DESIGN AND METHODS

A cross-sectional study was conducted in 108 perimenopausal and 127 postmenopausal women aged 43-65 years. All participants underwent lumbar spinal and nondominant femoral BMD evaluation by dual energy X-ray absorptiometry. Fourteen RANK, RANKL and OPG genotypes were determined by chip-based MALDI-TOF mass spectrometry. The differences between the BMDs of the RANK genotypes were analyzed.

RESULTS

Five SNPs (rs6993813, rs4355801, rs1032129 and rs2073618 in OPG and rs3018362 in RANK) were significantly associated with BMD or with BMD adjusted for body weight or years since menopause, mostly at the femoral neck but also partly at the total hip (p<0.05). The risk allele frequencies observed in our sample were different from those found in Europeans but the effects of these risk alleles on BMD values had the same direction in our cohort as in Europeans, except for rs3018362 with G as the risk allele, which was contrary to other studies. None of the SNPs in RANKL were associated with BMD at any anatomical site.

CONCLUSIONS

Our findings suggest that OPG and RANK but not RANKL genetic polymorphisms influence BMD mainly in the femoral neck in peri- and postmenopausal Chinese women. This contributes to the understanding of the role of genetic variation in this pathway in determining bone health.

Familial resemblance of bone turnover rate in men aged 40 and over-the MINOS study

Familial resemblance of bone mineral density (BMD) is well known in both sexes. Fewer data concern the familial resemblance of bone turnover markers (BTMs) and bone size in men. Our aim was to assess the correlation of BMD, bone size, BTM levels and hormones regulating bone turnover in 50 pairs of brothers aged ≥ 40 and 50 pairs of unrelated men matched for age, weight and height. BMD was measured at the lumbar spine, hip, forearm and whole body. We measured serum osteocalcin (OC), bone-specific alkaline phosphatase (bone ALP), N-terminal propeptide of type I procollagen (PINP) and C-terminal telopeptide of type I collagen (CTX-I) as well as urinary free and total deoxypyridinoline (DPD) and CTX-I. After adjustment for age, weight, bioavailable 17β-estradiol, and parathyroid hormone, all the BTMs (except bone ALP) were significantly correlated in the brothers (ICC = 0.36-0.64). Most of these correlations were significantly stronger than in the unrelated men. Bone size correlated significantly between the brothers (ICC = 0.55-0.65). These correlations were significantly stronger than in the unrelated men. BMD correlated between the brothers at most of the skeletal sites and, for some of them, more strongly than in the unrelated men. Serum levels of LDL-cholesterol and triglycerides were significantly correlated in the brothers, but not more strongly than in the unrelated men. BTM levels correlated independently in the brothers aged ≥ 40, when their shared environment was limited. These data suggest a substantial hereditary determinism of the BTM levels in men.

Genetic polymorphism of the OPG gene associated with breast cancer

Background

The receptor activator of NF-κB (RANK), its ligand (RANKL) and osteoprotegerin (OPG) have been reported to play a role in the pathophysiological bone turnover and in the pathogenesis of breast cancer. Based on this we investigated the role of single nucleotide polymorphisms (SNPs) within RANK, RANKL and OPG and their possible association to breast cancer risk.

Methods

Genomic DNA was obtained from Caucasian participants consisting of 307 female breast cancer patients and 396 gender-matched healthy controls. We studied seven SNPs in the genes of OPG (rs3102735, rs2073618), RANK (rs1805034, rs35211496) and RANKL (rs9533156, rs2277438, rs1054016) using TaqMan genotyping assays. Statistical analyses were performed using the χ²-tests for 2 x 2 and 2 x 3 tables.

Results

The allelic frequencies (OR: 1.508 CI: 1.127-2.018, p=0.006) and the genotype distribution (p=0.019) of the OPG SNP rs3102735 differed significantly between breast cancer patients and healthy controls. The minor allele C and the corresponding homo- and heterozygous genotypes are more common in breast cancer patients (minor allele C: 18.4% vs. 13.0%; genotype CC: 3.3% vs. 1.3%; genotype CT: 30.3% vs. 23.5%). No significantly changed risk was detected in the other investigated SNPs. Additional analysis showed significant differences when comparing patients with invasive vs. non-invasive tumors (OPG rs2073618) as well as in terms of tumor localization (RANK rs35211496) and body mass index (RANKL rs9533156 and rs1054016).

Conclusions

This is the first study reporting a significant association of the SNP rs3102735 (OPG) with the susceptibility to develop breast cancer in the Caucasian population.

Susceptibility genes for osteoporotic fracture in postmenopausal Chinese women

To identify the susceptibility genes for osteoporotic fracture in postmenopausal Chinese women, a two-stage case-control association study using joint analysis was conducted in 1046 patients with nontraumatic vertebra, hip, or distal radius fractures and 2303 healthy controls. First, 113 single-nucleotide polymorphisms (SNPs) in 16 potential osteoporosis candidate genes reported in recent genomewide association studies, meta-analyses studies, large-scale association studies, and functional studies were genotyped in a small-sample-size subgroup consisting of 541 patients with osteoporotic fractures and 554 healthy controls. Variants and haplotypes in SPTBN1, TNFRSF11B, CNR2, LRP4, and ESR1 that have been identified as being associated with osteoporotic fractures were further reanalyzed in the entire case-control group. We identified one SNP in TNFRSF11B (rs3102734), three SNPs in ESR1 (rs9397448, rs2234693, and rs1643821), two SNPs in LRP4 (rs17790156 and rs898604), and four SNPs in SPTBN1 (rs2971886, rs2941583, rs2941584, and rs12475342) were associated with all of the broadly defined osteoporotic fractures. The most significant polymorphism was rs3102734, with increased risk of osteoporotic fractures (odds ratio, 1.35; 95% confidence interval [CI], 1.17-1.55, Bonferroni p = 2.6 × 10(-4) ). Furthermore, rs3102734, rs2941584, rs12475342, rs9397448, rs2234693, and rs898604 exhibited significant allelic, genotypic, and/or haplotypic associations with vertebral fractures. SNPs rs12475342, rs9397448, and rs2234693 showed significant genotypic associations with hip fractures, whereas rs3102734, rs2073617, rs1643821, rs12475342, and rs2971886 exhibited significant genotypic and/or haplotypic associations with distal radius fractures. Accordingly, we suggest that in addition to the clinical risk factors, the variants in TNFRSF11B, SPTBN1, ESR1, and LRP4 are susceptibility genetic loci for osteoporotic fracture in postmenopausal Chinese women.

Host genome, epigenome, and oral microbiome interactions: toward personalized periodontal therapy

Periodontal diseases are multidimensional and complex. Bacterial content is the initiator, but disease progression depends on genetic and environmental parameters related to the host. Although bone loss magnitude is the common resulting outcome, the biologic process likely represents a unique inflammatory response characteristic to every individual. Therefore, it is obvious that practitioners must take into account the influence of these parameters and tailor a treatment accordingly. New, emerging deoxyribonucleotide-based technologies allow integration of the biologic impact of the environment, and periodontists should be prepared to incorporate these technologies into their practice to advance personalized medicine. This commentary provides updated insights on the distinctiveness of inflammation per individual in terms of microbiome and genome specificity and cites some educational resources helpful for implementing individualized therapy.

Bone health in adult cancer survivorship

Optimizing health outcomes, including prevention of osteoporotic fractures, is essential for promoting the well-being of the growing number of cancer survivors. Medical providers who participate in the care of cancer survivors should be aware that various cancer treatments may cause bone loss, which can increase the risk of subsequent of osteoporosis. Healthy bone remodeling is a balanced and dynamic equation between new bone formation and bone resorption. Aging, natural menopause, and cancer treatments such as surgical oophorectomy, gonadotropin-releasing hormone agonists, chemotherapy-induced ovarian failure, androgen deprivation therapy, and aromatase inhibitors can all promote bone loss. The WHO Fracture Assessment Tool can be used as a clinical aid to assess an individual's osteoporotic fracture risk, with or without bone mineral density measurements obtained from dual-energy x-ray absorptiometry. Preventative strategies include adequate calcium and vitamin D supplementation and modifying risk factors such as alcohol intake, tobacco use, and lack of exercise. Bisphosphonate therapy and rank-ligand monoclonal antibody therapy are the most commonly used agents for management of bone loss resulting from cancer treatment. This review will summarize the mechanisms by which cancer treatments cause bone loss as well provide screening and treatment recommendations for the management of bone loss.

A haplotype of MATN3 is associated with vertebral fracture in Chinese postmenopausal women: Peking Vertebral Fracture (PK-VF) study

The Matrilin3 gene (MATN3) encodes an extracellular matrix protein, which modulates chondrocyte differentiation. The aim of this study was to test for association of MATN3 polymorphisms with bone mineral density (BMD), fracture, vertebral fracture, bone turnover or 25-hydroxyvitamin D [25(OH)D] in postmenopausal women. A community-based population of 1488 postmenopausal women was randomly selected in Beijing. The history of fracture and vertebral fracture was obtained via questionnaire and vertebral X-ray respectively. BMD of lumbar spine (2-4), femoral neck and total hip were measured by dual energy X-ray absorptiometry. Serum N-terminal procollagen of type 1 collagen (P1NP), β-isomerized type I collagen C-telopeptide breakdown products (β-CTX) and 25(OH)D were quantified. Binary logistic regression revealed that Haplotype-4 was significantly associated with vertebral fracture risk in both additive model (p=0.023, OR=1.521) and dominant model (p=0.028, OR=1.623). The significance remained after 10,000 permutation tests to correct multiple testing (p=0.042). Re-selected age matched vertebral fracture case-control groups revealed similar associations in additive model (p=0.014, OR=1.927, 95%CI=1.142-3.253) and in dominant model (p=0.011, OR=2.231, 95%CI=1.200-4.148). However, no significant association was found between MATN3 polymorphisms and serum β-CTX, P1NP, 25(OH)D levels, or BMD. In linear regression, Haplotype-2 approached marginal significance in association with femoral neck BMD T-score (p=0.050), but this would account for only 0.2% of BMD variation in our sample. This study suggests that Haplotype-4 of MATN3 is associated with vertebral fracture risk independent of BMD in Chinese postmenopausal women. Efforts should be made to replicate our finding in other, similar and ethnically diverse, populations.

Influence of polymorphisms in the RANKL/RANK/OPG signaling pathway on volumetric bone mineral density and bone geometry at the forearm in men

We sought to determine the influence of single-nucleotide polymorphisms (SNPs) in RANKL, RANK, and OPG on volumetric bone mineral density (vBMD) and bone geometry at the radius in men. Pairwise tag SNPs (r (2) ≥ 0.8) for RANKL (n = 8), RANK (n = 44), and OPG (n = 22) and five SNPs near RANKL and OPG strongly associated with areal BMD in genomewide association studies were previously genotyped in men aged 40-79 years in the European Male Ageing Study (EMAS). Here, these SNPs were analyzed in a subsample of men (n = 589) who had peripheral quantitative computed tomography (pQCT) performed at the distal (4%) and mid-shaft (50%) radius. Estimated parameters were total and trabecular vBMD (mg/mm(3)) and cross-sectional area (mm(2)) at the 4% site and cortical vBMD (mg/mm(3)); total, cortical, and medullary area (mm(2)); cortical thickness (mm); and stress strain index (SSI) (mm(3)) at the 50% site. We identified 12 OPG SNPs associated with vBMD and/or geometric parameters, including rs10505348 associated with total vBMD (β [95% CI] = 9.35 [2.12-16.58], P = 0.011), cortical vBMD (β [95% CI] = 5.62 [2.10-9.14], P = 0.002), cortical thickness (β [95% CI] = 0.08 [0.03-0.13], P = 0.002), and medullary area (β [95% CI] = -2.90 [-4.94 to -0.86], P = 0.005) and rs2073618 associated with cortical vBMD (β [95% CI] = -4.30 [-7.78 to -0.82], P = 0.015) and cortical thickness (β [95% CI] = -0.08 [-0.13 to -0.03], P = 0.001). Three RANK SNPs were associated with vBMD, including rs12956925 associated with trabecular vBMD (β [95% CI] = -7.58 [-14.01 to -1.15], P = 0.021). There were five RANK SNPs associated with geometric parameters, including rs8083511 associated with distal radius cross-sectional area (β [95% CI] = 8.90 [0.92-16.88], P = 0.029). No significant association was observed between RANKL SNPs and pQCT parameters. Our findings suggest that genetic variation in OPG and RANK influences radius vBMD and geometry in men.

Functional polymorphisms within the TNFRSF11B (osteoprotegerin) gene increase the risk for low bone mineral density

Polymorphisms within the TNFRSF11B gene have been studied and associated with osteoporosis and fracture risk. Osteoprotegerin (OPG), the product of this gene, is a key negative regulator of osteoclastogenesis and is secreted by osteoblasts/stromal cells. A previous study in Maltese postmenopausal women showed positive association of low bone mineral density (BMD) with a polymorphism found within the promoter region of this gene (C950T). In this study, direct DNA sequencing revealed 12 variants with polymorphisms C950T, G1181C and rs4876869 observed to be in strong linkage disequilibrium. The constructed haplotype T-G-T was found to increase the risk for a low BMD, while C-G-T and C-C-C have a protective role; thus, we investigated the functional role of both C950T and rs4876869 in vitro. The promoter region, including the C950T alleles, was amplified by PCR, cloned into pGL3 enhancer vector and transfected into HeLa, COS-7 and RAW264.7 cell lines. After incubation, luciferase activity was measured. The T/C (rs4876869) change was tested for its possible effect on pre-mRNA splicing, using an exon-trapping vector. A statistical significant difference in gene expression was observed between the alleles for T950C, with the T allele showing a lower luciferase expression in all cell lines (P<0.01). For rs4876869, exon skipping was observed for the C allele, while only one transcript harbouring the whole exon was observed for the T allele. Our findings suggest that the T-G-T haplotype might be increasing the risk for osteoporosis due to lower quantities of the full OPG transcript being expressed resulting in a higher bone resorption.

Polymorphisms in genes involved in the NF-κB signalling pathway are associated with bone mineral density, geometry and turnover in men

INTRODUCTION

In this study, we aimed to investigate the association between single nucleotide polymorphisms (SNPs) within two genes involved in the NF-κB cascade (GPR177 and MAP3K14) and bone mineral density (BMD) assessed at different skeletal sites, radial geometric parameters and bone turnover.

METHODS

Ten GPR177 SNPs previously associated with BMD with genome-wide significance and twelve tag SNPs (r(2)≥0.8) within MAP3K14 (±10 kb) were genotyped in 2359 men aged 40-79 years recruited from 8 centres for participation in the European Male Aging Study (EMAS). Measurement of bone turnover markers (PINP and CTX-I) in the serum and quantitative ultrasound (QUS) at the calcaneus were performed in all centres. Dual energy X-ray absorptiometry (DXA), at the lumbar spine and hip, and peripheral quantitative computed tomography (pQCT), at the distal and midshaft radius, were performed in a subsample (2 centres). Linear regression was used to test for association between the SNPs and bone measures under an additive genetic model adjusting for study centre.

RESULTS

We validated the associations between SNPs in GPR177 and BMD(a) previously reported and also observed evidence of pleiotrophic effects on density and geometry. Rs2772300 in GPR177 was associated with increased total hip and LS BMD(a), increased total and cortical vBMD at the radius and increased cortical area, thickness and stress strain index. We also found evidence of association with BMD(a), vBMD, geometric parameters and CTX-I for SNPs in MAP3K14. None of the GPR177 and MAP3K14 SNPs were associated with calcaneal estimated BMD measured by QUS.

CONCLUSION

Our findings suggest that SNPs in GPR177 and MAP3K14 involved in the NF-κB signalling pathway influence bone mineral density, geometry and turnover in a population-based cohort of middle aged and elderly men. This adds to the understanding of the role of genetic variation in this pathway in determining bone health.

Association analyses suggest the effects of RANK and RANKL on age at menarche in Chinese women

OBJECTIVES

Age at menarche (AAM), the time of the first menstrual bleeding, is an important developmental milestone in the female life. It marks the beginning of the reproductive period. AAM is implicated in the risk of many health complications in later life. In this study, we conducted an analysis for association of single nucleotide polymorphisms (SNPs) and common haplotypes of two candidate genes, RANK (receptor activator of the NF-κB) and RANKL (receptor activator of the NF-κB ligand), with AAM in 825 unrelated Chinese women.

METHODS

In total, 73 SNPs of RANKL and 23 SNPs of RANK were genotyped. The SNPs and common haplotypes were then analyzed for their association with AAM. Age and age( 2 ) were used as covariates.

RESULTS

We found five individual SNPs (rs7239261, rs8094884, rs3826620, rs8089829, and rs9956850) of RANK significantly associated with AAM (p < 0.05). Although no significant association was identified for the RANKL gene, three polymorphisms showed nearly significant (0.05 < p < 0.08) association with AAM. Seven haplotypes of RANK were significantly associated with AAM (p < 0.05); the most significant association of the AT haplotype composed by rs1805034 and rs4524034 (p = 9.4 × 10(-4)) remained significant (p = 0.0235) after the Bonferroni correction for multiple testing. Three haplotypes of RANKL were significantly associated with AAM (p < 0.05). Importantly, the association of rs3826620 replicated our previous findings for Caucasian females.

CONCLUSIONS

The results of the present study suggest that the RANK and RANKL are two candidate genes for AAM in Chinese women.

Mouse Rankl expression is regulated in T cells by c-Fos through a cluster of distal regulatory enhancers designated the T cell control region

Receptor activator of NF-κB ligand (Rankl) is a TNF-like factor that induces the formation of osteoclasts responsible for bone resorption. Although T cell activation up-regulates this gene, the molecular mechanism of its transcriptional control remains unknown. We used ChIP-chip analysis in mouse primary T cells and a T cell hybridoma to define the regulatory enhancers responsible for this up-regulation and to characterize their properties. Elevated H3/H4 acetylation and increased RNA polymerase II density were evident at mRL-D5, a known enhancer located 76 kb upstream of the TSS, as well as at a cluster of regulatory sites located even further upstream between -123 to -156 kb, termed the T cell control region (TCCR). Based upon the ability of calcium signaling and MAPK inhibitors to block Rankl expression, we conducted further ChIP-chip analysis of the transcriptional mediators c-Fos, NF-κB, and Nfat. T cell activation induced c-Fos binding at the mRL-D5 enhancer and within the TCCR. The interaction of NF-κB was observed at the transcriptional start site and at mRL-D5. Both mRL-D5 and segments of the TCCR exhibited robust transcriptional activity in reporter assays, and site-specific mutagenesis of c-Fos and Nfat elements abrogated reporter activity, suggesting a role for both factors in the control of enhancer-mediated Rankl transcription. Finally, chromosome conformation capture analysis confirmed that mRL-D5 and segments of the TCCR were located in proximity to the Rankl gene promoter and thus potentially able to influence directly Rankl gene promoter activity. We conclude that both mRL-D5 and the TCCR represent control segments that play an integral role in Rankl expression in T cells.

Pharmacogenetics of osteoporosis-related bone fractures: moving towards the harmonization and validation of polymorphism diagnostic tools

Osteoporosis is one of the most common skeletal chronic conditions in developed countries, hip fracture being one of its major healthcare outcomes. There is considerable variation in the implementation of current pharmacological treatment and prevention, despite consistent recommendations and guidelines. Many studies have reported conflicting findings of genetic associations with bone density and turnover that might predict fracture risk. Moreover, it is not clear whether genetic differences exist in relation to the morbidity and efficiency of the pharmacotherapy treatments. Clinical response, including beneficial and adverse events associated with osteoporosis treatments, is highly variable among individuals. In this context, the present article intends to summarize putative candidate genes and genome-wide association studies that have been related with BMD and fracture risk, and to draw the attention to the need for pharmacogenetic methodology that could be applicable in clinical translational research after an adequate validation process. This article mainly compiles analysis of important polymorphisms in osteoporosis documented previously, and it describes the simple molecular biology tools for routine genotype acquisition. Validation of methods for the easy, fast and accessible identification of SNPs is necessary for evolving pharmacogenetic diagnostic tools in order to contribute to the discovery of clinically relevant genetic variation with an impact on osteoporosis and its personalized treatment.