Osteoporosis: A Silent Disease with Complex Genetic Contribution

Prevalence of osteoporosis and associated factors among people aged 50 years and older in the Madhesh province of Nepal: a community-based cross-sectional study

BACKGROUND

The high prevalence of osteoporosis has increased the economic burden on the health system globally. The burden of osteoporosis and its associated factors have not been adequately assessed in community settings in the Nepalese context thus far. Therefore, this study aimed to assess the prevalence of osteoporosis and its associated factors, lifestyle behaviors, and dietary calcium intake.

METHODS

A community-based cross-sectional study was conducted among 395 people aged 50 years and older in the Madhesh Province of Nepal between July 2022 and August 2023. The Osteoporosis Self-assessment Tools for Asians (OSTA) index was used to measure osteoporosis. A structured questionnaire was used to collect sociodemographic information, anthropometric data, lifestyle behavior, daily dietary calcium intake, and frequency of calcium-rich food consumption. A food frequency questionnaire and 24-hour recall methods were used to assess dietary intake. The chi-square test, binary logistic regression and Mann‒Whitney U test were applied to measure the association between predictors and the outcome of interest.

RESULTS

The prevalence of no risk, moderate risk and high risk of osteoporosis were 38.7%, 39%, and 22.3% respectively. The risk of osteoporosis was higher in females (aOR = 5.18, CI: 2.10-12.75, p < 0.001) and increased risk with advancing age (aOR = 32.49, CI: 14.02-75.28, p < 0.001). Similarly, underweight was associated with increased odds of having osteoporosis (aOR = 13.42, CI = 4.58-39.30, p < 0.001). The incidence of osteoporosis was strongly associated with daily calcium intake of 225 mg (100, 386).

CONCLUSION

This study revealed a high prevalence of osteoporosis among people aged 50 years and older due to the combined effect of being underweight and having inadequate calcium intake. Nutritional counselling services encourage people to consume sufficient calcium-rich food and adopt an appropriate lifestyle behaviours to maintain healthy body weight so that osteoporosis and osteoporotic fractures could be prevented. Further research can explore the impact of socioeconomic status and medical comorbidities on a large scale.

Use of data-independent acquisition mass spectrometry to identify an objective serum indicator of the need for osteoporotic therapeutic intervention

Osteoporosis is characterized by weakened bone microstructure and loss of bone mass. Current diagnostic criteria for osteoporosis are based on the T-score, which is a measure of bone mineral density. However, osteoporotic fragility fractures can occur regardless of the T-score, underscoring the need for additional criteria for the early detection of patients at fracture risk. To identify indicators of reduced bone strength, we performed serum proteomic analysis using data-independent acquisition mass spectrometry with serum samples from two patient groups, one with osteoporosis but no fractures and the other with osteopenia and fragility fractures. Collective evaluation of the results identified six serum proteins that changed to a similar extent in both patient groups compared with controls. Of these, extracellular matrix protein 1 (ECM1), which contributes to bone formation, showed the most significant increase in serum levels in both patient groups. An ELISA-based assay suggested that ECM1 could serve as a serum indicator of the need for therapeutic intervention; however, further prospective studies with a larger sample size are necessary to confirm these results. The present findings may contribute to the provision of early and appropriate therapeutic strategies for patients at risk of osteoporotic fractures. SIGNIFICANCE: This study aimed to identify objective serum indicators of the need for therapeutic intervention in individuals at risk of osteoporotic fracture. Comprehensive proteome analyses of serum collected from patients with osteoporosis but no fractures, patients with osteopenia and fragility fractures, and controls were performed by data-independent acquisition mass spectrometry. Collective evaluation of the proteome analysis data and ELISA-based assays identified serum ECM1 as a potential objective marker of the risk of fragility fractures in patients with osteoporosis or osteopenia. The findings are an important step toward the development of appropriate bone health management methods to improve well-being and maintain quality of life.

LDL receptor-related protein 5 rs648438 polymorphism is associated with the risk of skeletal fluorosis

To investigate the potential association between LRP5 rs648438 polymorphism and the risk of skeletal fluorosis (SF) was evaluated in a cross-sectional case-control study conducted in Shanxi, China, in 2019. A total of 973 individuals were enrolled in this study, in which cases and controls were 346 and 627, respectively. SF was diagnosed according to the standard WS/192-2008 (China). The LRP5 rs648438 was detected by the multiple PCR and sequencing. LRP5 rs648438 was found to follow a dominant genetic model using a web-based SNP-STATS software. Logistic regression analysis found that the TC/CC genotype of LRP5 rs648438 might be a protective factor for SF. When stratified by gender, this protective effect of TC/CC genotype in rs648438 was pronounced in males. There was an interaction between gender and rs648438 on risk of SF. Our study suggested that TC/CC genotype of rs648438 might be a protective factor for water-drinking-type skeletal fluorosis, especially in male participants.

Osteoporosis Prediction Using Machine-Learned Optical Bone Densitometry Data

Optical bone densitometry (OBD) has been developed for the early detection of osteoporosis. In recent years, machine learning (ML) techniques have been actively implemented for the areas of medical diagnosis and screening with the goal of improving diagnostic accuracy. The purpose of this study was to verify the feasibility of using the combination of OBD and ML techniques as a screening tool for osteoporosis. Dual energy X-ray absorptiometry (DXA) and OBD measurements were performed on 203 Thai subjects. From the OBD measurements and readily available demographic data, machine learning techniques were used to predict the T-score measured by the DXA. The T-score predicted using the Ridge regressor had a correlation of r = 0.512 with respect to the reference value. The predicted T-score also showed an AUC of 0.853 for discriminating individuals with osteoporosis. The results obtained suggest that the developed model is reliable enough to be used for screening for osteoporosis.

A decision support system for osteoporosis risk prediction using machine learning and explainable artificial intelligence

Osteoporosis is a metabolic bone condition that occurs when bone mineral density and mass decrease. This makes the bones weak and brittle. The disorder is often undiagnosed and untreated due to its asymptomatic nature until the manifestation of a fracture. Machine Learning (ML) is extensively used in diverse healthcare domains to analyze precise outcomes, provide timely risk scores, and allocate resources. Hence, we have designed multiple heterogeneous machine-learning frameworks to predict the risk of Osteoporosis. An open-source dataset of 1493 patients containing bone density, blood, and physical tests is utilized. Thirteen distinct feature selection techniques were leveraged to extract the most salient parameters. The best-performing pipeline consisted of a Forward Feature Selection algorithm followed by a custom multi-level ensemble learning-based stack, which achieved an accuracy of 89 %. Deploying a layer of explainable artificial intelligence using tools such as SHAP (SHapley Additive Values), LIME (Local Interpretable Model Explainer), ELI5, Qlattice, and feature importance provided interpretability and rationale behind classifier prediction. With this study, we aim to provide the holistic risk prediction of Osteoporosis and concurrently present a system for automated screening to assist physicians in making diagnostic decisions.

CircFam190a: a critical positive regulator of osteoclast differentiation via enhancement of the AKT1/HSP90β complex

The identification of key regulatory factors that control osteoclastogenesis is important. Accumulating evidence indicates that circular RNAs (circRNAs) are discrete functional entities. However, the complexities of circRNA expression as well as the extent of their regulatory functions during osteoclastogenesis have yet to be revealed. Here, based on circular RNA sequencing data, we identified a circular RNA, circFam190a, as a critical regulator of osteoclast differentiation and function. During osteoclastogenesis, circFam190a is significantly upregulated. In vitro, circFam190a enhanced osteoclast formation and function. In vivo, overexpression of circFam190a induced significant bone loss, while knockdown of circFam190a prevented pathological bone loss in an ovariectomized (OVX) mouse osteoporosis model. Mechanistically, our data suggest that circFam90a enhances the binding of AKT1 and HSP90β, promoting AKT1 stability. Altogether, our findings highlight the critical role of circFam190a as a positive regulator of osteoclastogenesis, and targeting circFam190a might be a promising therapeutic strategy for treating pathological bone loss.

NMP4, an Arbiter of Bone Cell Secretory Capacity and Regulator of Skeletal Response to PTH Therapy

The skeleton is a secretory organ, and the goal of some osteoporosis therapies is to maximize bone matrix output. Nmp4 encodes a novel transcription factor that regulates bone cell secretion as part of its functional repertoire. Loss of Nmp4 enhances bone response to osteoanabolic therapy, in part, by increasing the production and delivery of bone matrix. Nmp4 shares traits with scaling factors, which are transcription factors that influence the expression of hundreds of genes to govern proteome allocation for establishing secretory cell infrastructure and capacity. Nmp4 is expressed in all tissues and while global loss of this gene leads to no overt baseline phenotype, deletion of Nmp4 has broad tissue effects in mice challenged with certain stressors. In addition to an enhanced response to osteoporosis therapies, Nmp4-deficient mice are less sensitive to high fat diet-induced weight gain and insulin resistance, exhibit a reduced disease severity in response to influenza A virus (IAV) infection, and resist the development of some forms of rheumatoid arthritis. In this review, we present the current understanding of the mechanisms underlying Nmp4 regulation of the skeletal response to osteoanabolics, and we discuss how this unique gene contributes to the diverse phenotypes among different tissues and stresses. An emerging theme is that Nmp4 is important for the infrastructure and capacity of secretory cells that are critical for health and disease.

A case-control study coupling with meta-analysis elaborates decisive association between IGF-1 rs35767 and osteoporosis in Asian postmenopausal females

BACKGROUND

Osteoporosis (OP) is prevalent in postmenopausal women. Several studies investigated the association between IGF-1 polymorphisms and OP among postmenopausal females with conflicting outcomes.

OBJECTIVE

To investigate whether the IGF-1 (rs35767, rs2288377, rs5742612) were associated with OP in postmenopausal females.

METHODS

In case-control study, 95 OP cases and 222 healthy controls were recruited between March 2015 and July 2019. OP was diagnosed based on WHO criteria for diagnosis of OP as T score of bone mineral density (BMD) ≤-2.5; normal, as T score of BMD ≥-1. IGF-1 SNPs were genotyped by iPLEX Gold SNP genotyping. To be solid, related studies from PubMed, Embase, Cochrane, Web of science, and previous meta-analysis up until November 2020, along with our case-control study, were incorporated into a meta-analysis with criteria of significance using odds ratios (ORs) with corresponding 95% confidence intervals (CI) to evaluate risk factor of SNPs on OP. TSA was used to estimate the sample sizes required to achieve a conclusion.

RESULTS

In dominant model of our case-control study, we found nonsignificant association of rs35767 [Adj-OR: 0.95 (95% CI: 0.56-1.60)], rs2288377 [Adj-OR: 1.15 (95% CI: 0.67-1.97)], and rs5742612 [Adj-OR: 1.07 (95% CI: 0.62-1.83)] with OP in postmenopausal females. However, integration of our case-control study and 3 published studies, rs35767 [OR: 1.24 (95% CI: 1.05-1.47)] showed a conclusively risk association with OP in postmenopausal females judged by TSA with 2267 Asians.

CONCLUSIONS

This study demonstrates a crucial sample to conclude that IGF-1 rs35767 is significantly associated with OP in postmenopausal women.

MiR-124-3p Reduces Bone Mineral Density in Postmenopausal Osteoporosis Rats Through Regulating Signal Transducer and Activator of Transcription 3 Pathway

We aimed to study the effect of miR-124-3p on postmenopausal osteoporosis (POP) rats through regulating the signal transducer and activator of transcription 3 (STAT3) pathway. Rats were randomly divided into normal group, model group and miR-124-3p antagomir group. Enzyme-linked immunosorbent assay (ELISA) was performed to determine the levels of receptor activator of nuclear factor-κB (RANK) and osteoprotegerin (OPG). BMD of femur was significantly lower in model group and miR-124-3p antagomir group than that in normal group at 12 weeks after modeling, while it was significantly higher in miR-124-3p antagomir group than that in model group. Positive expression of BMP2 was obviously higher in miR-124-3p antagomir group than that in model group. Protein expression of p-STAT3 was evidently lower in miR-124-3p antagomir group than that in model group. Besides, POP rats have significantly increased level of miR-124-3p compared with that in normal group. In model group and miR-124-3p antagomir group, the content of OPG was remarkably lower, and the content of RANK was remarkably higher than those in normal group. In miR-124-3p antagomir group, the content of OPG was remarkably higher, and RANK was remarkably lower than those in model group. MiR-124-3p reduces BMD in POP rats through up-regulating the STAT3 pathway.

Optical bone densitometry robust to variation of soft tissue using machine learning techniques: validation by Monte Carlo simulation

SIGNIFICANCE

To achieve early detection of osteoporosis, a simple bone densitometry method using optics was proposed. However, individual differences in soft tissue structure and optical properties can cause errors in quantitative bone densitometry. Therefore, developing optical bone densitometry that is robust to soft tissue variations is important for the early detection of osteoporosis.

AIM

The purpose of this study was to develop an optical bone densitometer that is insensitive to soft tissue, using Monte Carlo simulation and machine learning techniques, and to verify its feasibility.

APPROACH

We propose a method to measure spatially resolved diffuse light from three directions of the biological tissue model and used machine learning techniques to predict bone density from these data. The three directions are backward, forward, and lateral to the direction of ballistic light irradiation. The method was validated using Monte Carlo simulations using synthetic biological tissue models with 1211 different random structural and optical properties.

RESULTS

The results were computed after a 10-fold cross-validation. From the simulated optical data, the machine learning model predicted bone density with a coefficient of determination of 0.760.

CONCLUSIONS

The optical bone densitometry method proposed in this study was found to be robust against individual differences in soft tissue.

Therapeutic Effects of Kefir Peptides on Hemophilia-Induced Osteoporosis in Mice With Deficient Coagulation Factor VIII

Osteoporosis is a clinically prevalent comorbidity in patients with hemophilia. A preventive effect of kefir peptides (KPs) on postmenopausal osteoporosis has been proved. The aim of this study was to evaluate the therapeutic effect of KPs for the treatment of osteoporosis in coagulation factor VIII (FVIII) gene knockout mice (F8KO), a model of hemophilia A. In this study, male F8KO mice at 20 weeks of age were orally administered different doses of KPs for 8 weeks. The therapeutic effects of KPs were shown in the femoral trabeculae and the 4th lumbar vertebrae, which increased the trabecular bone mineral density (BMD), bone volume (Tb.BV/TV), and trabecular number (Tb.N) and decreased the trabecular separation (Tb.Sp), and they were also observed in the femoral cortical bones, in which the mechanical properties were enhanced in a dose-dependent manner. Characterization of receptor activator of nuclear factor κB ligand (RANKL), osteoprotegerin (OPG), and interleukin 6 (IL-6) demonstrated that the serum RANKL/OPG ratio and IL-6 levels were significantly decreased in the F8KO mice after the KP treatment. Tartrate-resistant acid phosphatase (TRAP) staining of mature osteoclasts indicated that the therapeutic effect of KPs in F8KO mice was associated with the functions of KPs to inhibit RANKL-induced osteoclastogenesis by reducing serum RANKL/OPG ratio and IL-6 secretion. The present study is the first to address the potentials of KPs for the treatment of hemophilia-induced osteoporosis in mice and it also provides useful information for the application of KPs as a complementary therapy for the treatment of osteoporosis in hemophilic patients.

Bone mineral density in high-level endurance runners: part A-site-specific characteristics

PURPOSE

Physical activity, particularly mechanical loading that results in high-peak force and is multi-directional in nature, increases bone mineral density (BMD). In athletes such as endurance runners, this association is more complex due to other factors such as low energy availability and menstrual dysfunction. Moreover, many studies of athletes have used small sample sizes and/or athletes of varying abilities, making it difficult to compare BMD phenotypes between studies.

METHOD

The primary aim of this study was to compare dual-energy X-ray absorptiometry (DXA) derived bone phenotypes of high-level endurance runners (58 women and 45 men) to non-athletes (60 women and 52 men). Our secondary aim was to examine the influence of menstrual irregularities and sporting activity completed during childhood on these bone phenotypes.

RESULTS

Female runners had higher leg (4%) but not total body or lumbar spine BMD than female non-athletes. Male runners had lower lumbar spine (9%) but similar total and leg BMD compared to male non-athletes, suggesting that high levels of site-specific mechanical loading was advantageous for BMD in females only and a potential presence of reduced energy availability in males. Menstrual status in females and the number of sports completed in childhood in males and females had no influence on bone phenotypes within the runners.

CONCLUSION

Given the large variability in BMD in runners and non-athletes, other factors such as variation in genetic make-up alongside mechanical loading probably influence BMD across the adult lifespan.

Vitamin D receptor Bsm I polymorphism and osteoporosis risk in postmenopausal women: a meta-analysis from 42 studies

OBJECTIVE

This study aimed to quantitatively summarize the evidence for VDR BsmI gene polymorphism and osteoporosis risk in postmenopausal women.

MATERIALS AND METHODS

The PubMed, EMBASE, Weipu, CNKI, and Wanfang databases were searched for eligible studies. Case-control studies containing available genotype frequencies of B/b were chosen, and odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of this association.

RESULTS

4485 osteoporosis and 5490 controls were identified in our meta-analysis. In the stratified analysis, a significant association was observed between VDR BsmI gene polymorphism and osteoporosis susceptibility in Caucasians (additive model: OR = 0.809, 95% CI 0.678~0.965, p = 0.019; recessive model: OR = 0.736, 95% CI 0.568~0.955, p = 0.021; and co-dominant model: bb vs. BB OR = 0.701, 95% CI 0.511~0.962 p = 0.028), and we failed to find any significant relationship in Asians.

CONCLUSION

The present meta-analysis suggests that VDR BsmI genotype is associated with increased risk of postmenopausal osteoporosis in Caucasians but not in Asians. To draw comprehensive and true conclusions, further prospective studies with larger numbers of participants worldwide are needed to examine associations between VDR BsmI polymorphism and osteoporosis in postmenopausal women.

Targeted next generation sequencing of nine osteoporosis-related genes in the Wnt signaling pathway among Chinese postmenopausal women

PURPOSE

This study aimed to explore the association between low-frequency and rare variants of Wnt signaling genes and postmenopausal osteoporosis (OP) by the next generation sequencing (NGS) technology.

METHODS

We performed targeted NGS of nine Wnt signaling genes in 400 Chinese postmenopausal women, including 226 cases with decreased bone mineral density (BMD) and 174 controls with normal values. Proxy External Controls Association Test (ProxECAT) and logistic regression analysis were performed by data from internal cases (n = 226) and Genome Aggregation Database (gnomAD) East Asian controls (n = 9435).

RESULTS

The genomic region of interest (ROI) of 94 functional low-frequency and rare variants was associated with OP risk (P < 0.05). The LGR6 gene was associated significantly with OP risk and BMD measurements (BMD, T-score and Z-score) (adjusted-P < 0.05) after adjusting for confounders. The allele A of rs199693693 (K82N) in LRP6 and G of novel variant 1: 202287949 (R840G) in LGR6 were associated with higher BMD, T-score, and Z-score (all adjusted-P < 0.05). ProxECAT showed that LGR4 was significantly different between the internal cases and the external controls (all adjusted-P < 0.05). Logistic regression analysis revealed that the allele G of rs765778410 (T645A) (OR = 26.16, 95% CI: 4.36-156.95, adjusted-P value = 0.026) in LGR6 and A of rs61370283 (L987M) (OR = 15.39, 95% CI: 2.98-79.55, adjusted-P value = 0.037) in LRP5 were associated with increased risk of postmenopausal OP.

CONCLUSION

The LGR4 and LGR6 genes and four potential functional rare variants associate with postmenopausal OP risk. These results highlight the significance of rare functional variants in postmenopausal OP genetics and provide new insights into the potential mutations in this field.

Relationship of COL9A1 and SOX9 Genes with Genetic Susceptibility of Postmenopausal Osteoporosis

As one of the most common types of osteoporosis, postmenopausal osteoporosis (PMOP) is caused by both genetic and environmental factors. Previous studies have indicated that SOX9 activity is tightly regulated to ensure normal bone mineral density (BMD) in the adult skeleton, and the COL9A1 promoter region can be transactivated by SOX9. In this study, we aimed to investigate the potential association between PMOP and the COL9A1 and SOX9 genes. A total of 10,443 postmenopausal women, including 2288 patients and 3557 controls in the discovery stage and 1566 patients and 3032 controls in the validation stage, were recruited. Forty-three tag SNPs (36 in COL9A1 and 7 in SOX9) were selected for genotyping to evaluate the association of the SOX9 gene with PMOP and BMD. Association and bioinformatics analyses were performed for PMOP. BMD and serum level of SOX9 were also utilized as quantitative phenotypes in further analyses. SNP rs73354570 of SOX9 was significantly associated with PMOP in both discovery stages (OR 1.24 [1.10-1.39], P = 3.56 × 10^-4, χ² = 12.75) and combined samples (OR 1.25 [1.15-1.37], P = 5.25 × 10^-7, χ² = 25.17). Further analyses showed that the SNP was also significantly associated with BMD and serum levels of the SOX9 protein. Our results provide further supportive evidence for the association of the SOX9 gene with PMOP and of the SOX9 gene with the variation of BMD in postmenopausal Han Chinese women. This study supports a role for SOX9 in the etiology of PMOP, adding to the current understanding of the susceptibility of osteoporosis.

Comparison of bone biomechanical properties after bone marrow mesenchymal stem cell or alendronate treatment in an osteoporotic animal model

The aim of this study was to explore the effects of bone marrow mesenchymal stem cells (BMMSCs) and alendronate sodium (ALN) intervention on osteoporosis (OP). Sixty-eight 6-month-old healthy female Sprague Dawley (SD) rats were used to generate an OP model by removal of the ovaries. After 12 weeks, rats were treated with BMMSCs (BMMSC group) or ALN (ALN group) for 5 weeks. Serum type I collagen C terminal peptide (CTX_1), procollagen type I N-terminal propeptide (PINP), and bone alkaline phosphatase (BALP) were tested along with the femur bone density and other properties, including bone mineral density (BMD), BALP, percent trabecular area (BV/TV), trabecular thickness (Tb.Th), trabecular number (TbN), maximum load, maximum stress, maximum strain, and elastic modulus. BMD, BALP, BV/TV, Tb.Th, TbN, maximum load, maximum stress, maximum strain, and elastic modulus values were higher in the BMMSC group versus the ALN group relative to the control group (p < 0.05); CTX_1, PINP, trabecular separation (Tb.Sp), and osteoclast number (OC.N) were lowest in the BMMSC group versus the ALN group relative to the control group (p < 0.05). Both BMMSCs and ALN could improve the metabolic function and bone quality in osteoporotic mice while restoring the strength and toughness of bones. The intervention effects of BMMSCs are better than ALN in this model.

Polymorphisms of FDPS, LRP5, SOST and VKORC1 genes and their relation with osteoporosis in postmenopausal Romanian women

OBJECTIVES

This study aimed to assess the relationship between bone mineral density and genotypes of four polymorphisms in previously detected osteoporosis-candidate genes (FDPS rs2297480, LRP5 rs3736228, SOST rs1234612, VKORC1 rs9934438) in postmenopausal Romanian women with primary osteoporosis.

METHODS

An analytical, prospective, transversal, observational, case-control study on 364 postmenopausal Romanian women was carried out between June 2016 and August 2017 in Cluj Napoca, Romania. Clinical data and blood samples were collected from all study participants. Four polymorphisms were genotyped using TaqMan SNP Genotyping assays, run on a QuantStudio 3 real-time PCR machine.

RESULTS

Women with TT genotype in FDPS rs2297480 had significantly lower bone mineral density values in the lumbar spine and total hip, and the presence of the T allele was significantly associated with the osteoporosis. Women carrying the CC genotype in LRP5 rs3736228 tend to have lower bone mineral density values in the femoral neck and total hip. No significant association was found for the genotypes of SOST rs1234612 or VKORC1 rs9934438.

CONCLUSIONS

Our study showed a strong association between bone mineral density and polymorphisms in the FDPS gene, and a borderline association with LRP5 and SOST polymorphisms in postmenopausal Romanian women with osteoporosis. No association was found for VKORC1.

An insight into the paradigms of osteoporosis: From genetics to biomechanics

Considered as one of the major epidemics of the 21st century, osteoporosis affects approximately 200 million people globally, with significant worldwide impact on rates of morbidity and mortality and massive socioeconomic burdens. Mainly characterized by decreased bone mineral density (BMD) and increased risk of bone fragility/deterioration, this devastating silent epidemic typically has no symptoms until a fracture occurs. The multifactorial disease, osteoporosis is instigated by complex interactions between genetic, metabolic and environmental factors, with severe impact on the biomechanics of the musculoskeletal system. This article provides a review of the epidemiology, genetic and biomechanical aspects of primary osteoporosis. The review begins with a summary of the epidemiology and global prevalence of osteoporosis. Sections 1 and 2 discuss the genetic associations and molecular signaling pathways involved in normal and pathological osteogenesis while Section 3 explores the biomechanics of osteoporosis and its quantitative damaging effects on critical bone mechanical properties, and associated bone remodeling. Overall, this review summarizes the recent findings about osteoporosis and emphasizes the importance of an integrative holistic approach in investigating osteoporosis towards providing better informed, more effective preventive and treatment modalities. Importantly, this work also explores the limited available literature on the various aspects of osteoporosis in the United Arab Emirates (UAE), Gulf Cooperation Council (GCC), and Middle East despite its alarming prevalence in the region, and highlights the need for further research and studies taking into consideration the importance of the vitamin D receptor (VDR) gene influencing the development of osteoporosis.

The associations of TNF-α gene polymorphisms with bone mineral density and risk of osteoporosis: A meta-analysis

OBJECTIVE

Fracture is a common consequence of osteoporosis and is associated with high morbidity and mortality. Recently, increasing evidence has suggested that polymorphisms in tumor necrosis factor-α (TNF-α) gene were associated with osteoporosis risk and bone mineral density (BMD), but results remain conflicting. We herein performed a meta-analysis based on evidence currently available from the literature to make a more precise estimation of these relationships.

METHODS

The PubMed, EMBASE, Cochrane Library, CNKI (China National Knowledge Infrastructure) and Wan Fang databases were searched for eligible studies. Articles meeting the inclusion criteria were comprehensively reviewed and all available data were accumulated. The pooled odds ratios (ORs) or mean differences (MDs) and corresponding 95% confidence intervals (CIs) were applied to assess the strength of the relationships.

RESULTS

A total of 15 studies involving 5273 subjects were included in our meta-analysis. The GG genotype of TNF-α G308A was associated with an increased risk of osteoporosis under a mutant model (GG vs GA+AA: OR = 0.63, 95% CI: 0.51-0.77, P < 0.0001, I²  = 31%). Additionally, we also observed a significant association between G308A polymorphism and BMD of lumbar spine (AA vs GG: P = 0.01, I²  = 53%). However, TNF-α T1031C, C857T and C863A polymorphisms had no obvious impacts on osteoporosis risk.

CONCLUSIONS

The present meta-analysis demonstrated that TNF-α G308A polymorphism may act as a potential candidate biomarker for screening, diagnosis, and treatment of osteoporosis, which will help improve individualized therapy of osteoporosis patients in clinics.

Effect of cervus and cucumis polypeptide combined with zoledronic acid on bone metabolic biochemical markers in glucocorticoids - Induced osteoporosis patients

Objective

To investigate the effect of cervus and cucumis polypeptide combined with zoledronic acid on bone metabolic biochemical markers in glucocorticoids - induced osteoporosis patients.

Methods

A total of 100 patients with glucocorticoids - induced osteoporosis admitted to our hospital from January 2015 to June 2017 were enrolled in this study. Patients were divided into observation group and control group by random number table method, 50 cases in each group. Patients in the observation group were treated with deer melon polypeptide in combination with zoledronic acid, and patients in the control group were treated with zoledronic acid alone. The patients in both groups were treated for 2 months. The changes of bone mineral density (BMD) and biochemical markers of bone metabolism in lumbar vertebrae L1-4, left femoral neck and large trochanter were analyzed before and after treatment.

Results

The pre- BMD at lumbar spine L_1-4, left femoral neck and great trochanter had no statistic difference (P > 0.05), the BMD at each sites improved after treatment, and the difference were statistical before and after treatment (P < 0.05). BMD at above sites of two groups after treatment had statistical difference (P < 0.05), and the BMD at lumbar spine L_1-4, left femoral neck and great trochanter in the observation group was higher than that of the control group. There were no significant differences in PTH, 25-(OH)D3, TRACP, β-CTX and BGP levels between the two groups before treatment (P > 0.05). The levels of 25-(OH)D3, TRACP, β-CTX and BGP in the two groups were significantly improved after treatment (P < 0.05), and the levels of PTH, TRACP and β-CTX in the observation group were significantly lower than those in the control group. The levels of 25-(OH) D3 and BGP were significantly higher than those of the control group (P < 0.05).

Conclusion

The cervus and cucumis polypeptide combined with zoledronic acid can improve the BMD at lumbar spine L_1-4, left femoral neck and great trochanter, and ameliorate the bone metabolic biochemical markers for patients with glucocorticoids - induced osteoporosis.

The interactions of physical activity, exercise and genetics and their associations with bone mineral density: implications for injury risk in elite athletes

Low bone mineral density (BMD) is established as a primary predictor of osteoporotic risk and can also have substantial implications for athlete health and injury risk in the elite sporting environment. BMD is a highly multi-factorial phenotype influenced by diet, hormonal characteristics and physical activity. The interrelationships between such factors, and a strong genetic component, suggested to be around 50-85% at various anatomical sites, determine skeletal health throughout life. Genome-wide association studies and case-control designs have revealed many loci associated with variation in BMD. However, a number of the candidate genes identified at these loci have no known associated biological function or have yet to be replicated in subsequent investigations. Furthermore, few investigations have considered gene-environment interactions-in particular, whether specific genes may be sensitive to mechanical loading from physical activity and the outcome of such an interaction for BMD and potential injury risk. Therefore, this review considers the importance of physical activity on BMD, genetic associations with BMD and how subsequent investigation requires consideration of the interaction between these determinants. Future research using well-defined independent cohorts such as elite athletes, who experience much greater mechanical stress than most, to study such phenotypes, can provide a greater understanding of these factors as well as the biological underpinnings of such a physiologically "extreme" population. Subsequently, modification of training, exercise or rehabilitation programmes based on genetic characteristics could have substantial implications in both the sporting and public health domains once the fundamental research has been conducted successfully.

A specific haplotype in potential miRNAs binding sites of secreted frizzled-related protein 1 (SFRP1) is associated with BMD variation in osteoporosis

PURPOSE

Osteoporosis is an important multifactorial disease which is largely influenced by Wnt signaling pathway. Considering regulatory single nucleotide polymorphisms in Wnt signaling pathway may pave the road of understanding the genetic basis of predisposition to osteoporosis. The aim of this study was to determine the possible association between variants of SFRP1 and WNT5b, and osteoporosis incidence risk.

METHODS

The study population comprised 186 osteoporotic patients and 118 normal subjects from Amirkola Health and Ageing Project. rs1127379 (c.1406A>G) and rs3242 (c.3132C>T) variants in 3'UTR of SFRP1 gene, and rs3803164 (c.236C>T) in 3'UTR and rs735890 (c.622-536A>G) in intron 4 of WNT5b gene were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Regression analyses were used to calculate the association of genotype frequencies with bone mineral density (BMD) and bone mineral content (BMC) values of participants. Bioinformatics algorithms were used to detect the effect of each SNP on the secondary structure of mRNA, and predict putative 3'UTR microRNA target sites and splicing sites changes by related SNPs.

RESULTS

WNT5b rs735890 was associated with lumbar spine BMD, BMC, and femoral neck BMC (P = 0.035, P = 0.007, and P = 0.038, respectively). WNT5b rs3803164, and SFRP1 rs3242 were significantly associated with lumbar spine BMD (P = 0.028 and P = 0.030, respectively). SFRP1 rs1127379 was associated with lumbar spine BMD in the male gender. Haplotype analysis showed a significant association of SFRP1 c.[1406A; 3132C] haplotype with lumbar spine BMD, and BMC (P = 0.019 and P = 0.030, respectively), and SFRP1 c.[1406G; 3132C] haplotype with lumbar spine BMC (P = 0.045). In silico analyses revealed that the G allele of SFRP1 rs1127379, and WNT5b rs3803164 appear as more possible target sites for many miRNAs.

CONCLUSIONS

This study is the first evidence of the association of WNT5b rs735890, and c.[1406A; 3132C] and c.[1406G; 3132C] haplotypes of SFRP1 with BMD variation in osteoporosis, probably by altering microRNA target sites, in elderly persons.

Association of interleukin-6 (rs1800796) but not transforming growth factor beta 1 (rs1800469) with serum calcium levels in osteoporotic patients

BACKGROUND

Osteoporosis is a multifactorial disease with a strong genetic influence. Recent studies have demonstrated that cytokines, such as TGF-β1 and interleukin 6 (IL-6) play complex roles in the normal bone metabolism and pathophysiology of osteoporosis. Here, we investigated the roles of 2 polymorphisms mapping to the promoters of TGF-β1and IL-6 genes on the genetic susceptibility to osteoporosis as well as calcium and vitamin D levels.

METHODS

A cohort of 297 elderly participants in northern Iran comprising 181 osteoporotic patients (mean age ± SD, 68.36 ± 7.21 years) and 116 unrelated healthy controls (mean age ± SD, 64 ± 5.44 years) was studied for TGF-β1(C-509T) and IL-6 (G-634C) polymorphisms using PCR-RFLP method.

RESULTS

A significant relationship was observed between calcium level and IL-6 genotypes in osteoporotic males (P = 0.011) and females (P = 0.020). No significant differences were observed between osteoporotic and control groups with respect to allele frequency or genotype distribution based on the 2 selected polymorphisms under different genetic models. The results remained the same after comparing the BMD values of either the femur neck or lumbar spine with the genotypes of the elderly men and women when analyzed separately.

CONCLUSION

IL-6 genotype influences serum calcium levels in osteoporotic patients. The lack of association between the common genetic variations of TGF-β1 and IL-6 genes, and BMD highlights the complex genetic background of osteoporosis in the north of Iran.

Enhancer variants reveal a conserved transcription factor network governed by PU.1 during osteoclast differentiation

Genome-wide association studies (GWASs) have been instrumental in understanding complex phenotypic traits. However, they have rarely been used to understand lineage-specific pathways and functions that contribute to the trait. In this study, by integrating lineage-specific enhancers from mesenchymal and myeloid compartments with bone mineral density loci, we were able to segregate osteoblast- and osteoclast (OC)-specific functions. Specifically, in OCs, a PU.1-dependent transcription factor (TF) network was revealed. Deletion of PU.1 in OCs in mice resulted in severe osteopetrosis. Functional genomic analysis indicated PU.1 and MITF orchestrated a TF network essential for OC differentiation. Several of these TFs were regulated by cooperative binding of PU.1 with BRD4 to form superenhancers. Further, PU.1 is essential for conformational changes in the superenhancer region of Nfatc1. In summary, our study demonstrates that combining GWASs with genome-wide binding studies and model organisms could decipher lineage-specific pathways contributing to complex disease states.

Genetic variation in non-coding regions of DNA could raise osteoporosis risk by affecting osteoclast differentiation. Osteoporosis occurs when the normal process of bone remodeling by osteoblasts and osteoclasts falls out of balance. Genome-wide association studies (GWAS) have identified numerous single nucleotide polymorphisms (SNPs) associated with osteoporosis, but how these affect specific cell types was unclear. Sudarshana Sharma and Michael Ostrowski at the Medical University of South Carolina and colleagues wondered if variations in non-coding ‘enhancer’ regions of DNA, might shed light on the molecular underpinnings of osteoporosis. So, they overlaid SNPs associated with reduced bone mineral density onto enhancers in mesenchymal and myeloid cells—the precursors of osteoblasts and osteoclasts—identifying a transcription factor network in myeloid cells that drives the differentiation of osteoclasts. When this was disrupted in mice, severe defects in osteoclast differentiation and function resulted.

Association of the insulin-like growth factor-1 single nucleotide polymorphisms rs35767, rs2288377, and rs5742612 with osteoporosis risk: A meta-analysis

BACKGROUND

Insulin-like growth factor-1 (IGF-1) plays an important role in the regulation of bone formation and mineralization. We aimed to perform a meta-analysis to assess the association of three IGF-1 single nucleotide polymorphisms (SNPs) rs35767, rs2288377, and rs5742612 with osteoporosis risk.

METHODS

A systematic search of PubMed, Web of Science, Embase, Medline, Scopus, CNKI, and Wanfang databases was conducted. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using a fixed effects model.

RESULTS

Four Chinese case-control studies with a total of 2807 participants were included in this meta-analysis. The results revealed an association between rs35767 and osteoporosis risk in all study subjects (women and men) in dominant (OR 1.32, 95% CI 1.13-1.53, P < .001), recessive (OR 1.73, 95% CI 1.35-2.21, P < .001), homozygote (OR 1.89, 95% CI 1.46-2.45, P < .001), and allelic (OR 1.31, 95% CI 1.18-1.47, P < .001) models. Subgroup analysis according to gender showed that rs35767 was associated with osteoporosis risk in women under dominant (OR 1.29, 95% CI 1.08-1.54, P = .005), recessive (OR 1.59, 95% CI 1.19-2.12, P = .002), homozygote (OR 1.73, 95% CI 1.28-2.34, P < .001), and allelic (OR 1.28, 95% CI 1.12-1.47, P < .001) models. Meta-analysis did not find associations of rs2288377 and rs5742612 with osteoporosis risk. There was no evidence of between-study heterogeneity and publication bias.

CONCLUSION

Our results suggest that rs35767 is associated with osteoporosis risk in Chinese, whereas there is no association of rs2288377 and rs5742612 with osteoporosis risk.

Delivery of antagomiR204-conjugated gold nanoparticles from PLGA sheets and its implication in promoting osseointegration of titanium implant in type 2 diabetes mellitus

Impaired osseointegration of the implant remains the big hurdle for dental implant therapy in diabetic patients. In this study, the authors first identified that miR204 was strikingly highly expressed in the bone mesenchymal stem cells (BMSCs) of diabetic rats. Forced expression of miR204 repressed the osteogenic potential of BMSCs, while inhibition of miR204 significantly increased the osteogenic capacity. Moreover, the miR204 inhibitor was conjugated with gold nanoparticles (AuNP-antagomiR204) and dispersed them in the poly(lactic-co-glycolic acid) (PLGA) solution. The AuNP-antagomiR204 containing PLGA solution was applied for coating the surface of titanium implant. Electron microscope revealed that an ultrathin sheet was formed on the surface of the implant, and the AuNPs were evenly dispersed in the coated PLGA sheet. Cellular experiments revealed that these encapsulated AuNP-antagomiR204 were able to be released from the PLGA sheet and uptaken by adherent BMSCs. In vivo animal study further confirmed that the AuNP-antagomiR204 released from PLGA sheet promoted osseointegration, as revealed by microcomputerized tomography (microCT) reconstruction and histological assay. Taken together, this study established that miR204 misexpression accounted for the deficient osseointegation in diabetes mellitus, while PLGA sheets aided the release of AuNP-antagomiR204, which would be a promising strategy for titanium implant surface functionalization toward better osseointegration.

Cytochrome P450 Genes (CYP2E1 and CYP1A1) Variants and Susceptibility to Chronic Hepatitis B Virus Infection

Hepatitis B virus (HBV) infection is a worldwide health concern which is associated with significant morbidity and mortality. Both viral and host factors have a significant effect on infection, replication and pathogenesis of HBV. The aim of this study was to investigate the effect of CYP2E1 and CYP1A1 genetic variants on susceptibility to HBV. 143 individuals including 54 chronic HBV patients and 89 healthy controls were enrolled in the genotyping procedure. rs2031920 and rs3813867 at CYP2E1 as well as rs4646421 and rs2198843 at CYP1A1 loci were studied in all subjects using PCR-RFLP (restriction fragment length polymorphism) analysis. Both variants at CYP2E1 locus were monomorphic in all studied subjects. Genotype frequency of rs4646421 was significantly different between chronic HBV patients and healthy blood donors (P = 0.04, OR 4.31; 95% CI 1.04-17.7). Furthermore, individuals carrying at least one C allele (CC or CT genotypes) for rs4646421 seemed to have a decrease risk of hepatitis in comparison with TT genotype (P = 0.039). Our results showed a relationship between rs4646421 TT genotype (rare genotype) and the risk for developing chronic HBV infection (four times higher). Further studies are needed to examine the role of CYP1A1 polymorphism in susceptibility to chronic HBV infection.

Sirtuin-3 Promotes Adipogenesis, Osteoclastogenesis, and Bone Loss in Aging Male Mice

Sirtuin-3 (Sirt3) is an essential metabolic regulatory enzyme that plays an important role in mitochondrial metabolism, but its role in bone marrow and skeletal homeostasis remains largely unknown. In this study, we hypothesize that increased expression of Sirt3 plays a role in skeletal aging. Using mice that overexpress Sirt3 [i.e., Sirt3 transgenic (Sirt3Tg)], we show that Sirt3 is a positive regulator of adipogenesis and osteoclastogenesis and a negative regulator of skeletal homeostasis. Sirt3Tg mice exhibited more adipocytes in the tibia compared with control mice. Bone marrow stromal cells (BMSCs) from Sirt3Tg mice displayed an enhanced ability to differentiate into adipocytes compared with control BMSCs. We found a 2.5-fold increase in the number of osteoclasts on the bone surface in Sirt3Tg mice compared with control mice (P < 0.03), and increased osteoclastogenesis in vitro. Importantly, Sirt3 activates the mechanistic target of rapamycin (mTOR) pathway to regulate osteoclastogenesis. Sirt3Tg male mice exhibited a significant reduction in cortical thickness at the tibiofibular junction (P < 0.05). In summary, Sirt3 activity in bone marrow cells is associated with increased adipogenesis, increased osteoclastogenesis through activation of mTOR signaling, and reduced bone mass. Interestingly, Sirt3 expression in bone marrow cells increases during aging, suggesting that Sirt3 promotes age-related adipogenesis and osteoclastogenesis associated with bone loss. These findings identify Sirt3 as an important regulator of adipogenesis and skeletal homeostasis in vivo and identify Sirt3 as a potential target for the treatment of osteoporosis.

P4 medicine and osteoporosis: a systematic review

BACKGROUND

Osteoporosis is the most frequent bone metabolic disease. In order to improve early detection, prediction, prevention, diagnosis, and treatment of the disease, a new model of P4 medicine (personalized, predictive, preventive, and participatory medicine) could be applied. The aim of this work was to systematically review the publications of four different types of "omics" studies related to osteoporosis, in order to discover novel predictive, preventive, diagnostic, and therapeutic targets for better management of the geriatric population.

METHODS

To systematically search the PubMed database, we created specific groups of criteria for four different types of "omics" information on osteoporosis: genomic, transcriptomic, proteomic, and metabolomic. We then analyzed the intersections between them in order to find correlations and common pathways or molecules with important roles in osteoporosis, and with a potential application in disease prediction, prevention, diagnosis, or treatment.

RESULTS

Altogether, 180 publications of "omics" studies in the field of osteoporosis were found and reviewed at first selection. After introducing the inclusion and exclusion criteria (the secondary selection), 46 papers were included in the systematic review.

CONCLUSIONS

The intersection of reviewed papers identified five genes (ESR1, IBSP, CTNNB1, SOX4, and IDUA) and processes like the Wnt pathway, JAK/STAT signaling, and ERK/MAPK, which should be further validated for their predictive, diagnostic, or other clinical value in osteoporosis. Such molecular insights will enable us to fit osteoporosis into the P4 strategy and could increase the effectiveness of disease prediction and prevention, with a decrease in morbidity in the geriatric population.

Osteoporosis: Modern Paradigms for Last Century's Bones

The skeleton is a metabolically active organ undergoing continuously remodelling. With ageing and menopause the balance shifts to increased resorption, leading to a reduction in bone mineral density and disruption of bone microarchitecture. Bone mass accretion and bone metabolism are influenced by systemic hormones as well as genetic and lifestyle factors. The classic paradigm has described osteoporosis as being a “brittle bone” disease that occurs in post-menopausal, thin, Caucasian women with low calcium intakes and/or vitamin D insufficiency. However, a study of black women in Africa demonstrated that higher proportions of body fat did not protect bone health. Isoflavone interventions in Asian postmenopausal women have produced inconsistent bone health benefits, due in part to population heterogeneity in enteric bacterial metabolism of daidzein. A comparison of women and men in several Asian countries identified significant differences between countries in the rate of bone health decline, and a high incidence rate of osteoporosis in both sexes. These studies have revealed significant differences in genetic phenotypes, debunking long-held beliefs and leading to new paradigms in study design. Current studies are now being specifically designed to assess genotype differences between Caucasian, Asian, African, and other phenotypes, and exploring alternative methodology to measure bone architecture.