An atlas of genetic influences on osteoporosis in humans and mice

Obstructive sleep apnea and osteoporosis: A bidirectional two-sample mendelian randomization analysis

BACKGROUND

Previous epidemiological studies have explored the association between obstructive sleep apnea (OSA) and osteoporosis (OP), with inconclusive results due to various biases. Herein, we sought to determine the causal association between OSA and OP through bidirectional two-sample Mendelian randomization analysis.

METHODS

Summary-level data for OSA were acquired from the FinnGen consortium, while data for fractures and BMDs (FA-BMD, FN-BMD, LS-BMD and eBMD) were derived from the UKBB and GEFOS. The inverse variance weighted (IVW) method was conducted as the main method, and several supplementary methods were further utilized for sensitivity analysis to strengthen the reliability of our findings.

RESULTS

The study findings strongly suggest a causal association between OSA and FA-BMD based on the IVW method (BETA = 0.404; 95 % CI = 0.208, 0.599; p = 5.28 × 10-5). However, OSA showed no significant causal relationship with eBMD (BETA = 0.052; 95 % CI = -0.018, 0.123; p = 0.145), FN-BMD (BETA = 0.095; 95 % CI = -0.009, 0.2; p = 0.073), LS-BMD (BETA = 0.021; 95 % CI = -0.082, 0.124; p = 0.695), and fractures (OR = 0.998; 95 % CI = 0.907, 1.098; p = 0.971). The conclusions from other analytical strategies were generally aligned with those of the IVW. No definitive causal effect of OP on OSA was observed in reverse analysis.

CONCLUSION

This research provided clear evidence of a causal association between OSA and FA-BMD, shedding light on the potential impact of OSA on bone metabolism.

The GWAS candidate far upstream element binding protein 3 (FUBP3) is required for normal skeletal growth, and adult bone mass and strength in mice

Bone mineral density (BMD) and height are highly heritable traits for which hundreds of genetic loci have been linked through genome wide association studies (GWAS). FUBP3 is a DNA and RNA binding protein best characterised as a transcriptional regulator of c-Myc, but little is known about its role in vivo. Single nucleotide polymorphisms in FUBP3 at the 9q34.11 locus have been associated with BMD, fracture and height in multiple GWAS, but FUBP3 has no previously established role in the skeleton. We analysed Fubp3-deficient mice to determine the consequence of FUBP3 deficiency in vivo. Mice lacking Fubp3 had reduced survival to adulthood and impaired skeletal growth. Bone mass was decreased, most strikingly in the vertebrae, with altered trabecular micro-architecture. Fubp3 deficient bones were also weak. These data provide the first functional demonstration that Fubp3 is required for normal skeletal growth and development and maintenance of adult bone structure and strength, indicating that FUBP3 contributes to the GWAS association of 9q34.11 with variation in height, BMD and fracture.

Association of nuclear magnetic resonance-based metabolomics with bone health in the UK Biobank

OBJECTIVES

The study aimed to explore associations of metabolomic data based on nuclear magnetic resonance (NMR) with the risk of fractures and bone mineral density (BMD).

METHODS

We included 69,963 participants without fractures at baseline in the UK Biobank. Cox proportional hazard models were used to estimate the associations of metabolomic biomarkers measured by NMR technology with the risk of all fractures and hip fracture. We used principal component analysis (PCA) to obtain uncorrelated principal components (PC), which were further used to estimate the associations of each PC with BMD, all fractures, and hip fracture separately.

RESULTS

During a median follow-up of 12.6 years, 3840 incidents of all fractures and 666 incidents of hip fracture were documented. Ninety-four of the 143 metabolomic biomarkers were significantly associated with incident all fractures, and 81 were significantly associated with incident hip fracture. The very low-density lipoprotein (VLDL) subclasses in different lipid constituents were associated with increased BMD at multiple sites, whereas high-density lipoprotein (HDL) subclasses were associated with decreased BMD. Higher concentrations of small (HR per SD increment: 0.92; 95 % CI: 0.88-0.97), medium (HR per SD increment: 0.91; 95 % CI: 0.88-0.94), and large (HR per SD increment: 0.93; 95 % CI: 0.90-0.96) low-density lipoprotein (LDL) particles were associated with a lower risk of all fractures. Similarly, higher VLDL subclasses (excluding very small VLDL particles) were associated with a lower risk of all fractures. Besides, higher levels of lipid constituents (including total lipids, cholesteryl esters, cholesterol, and free cholesterol) of very large and large HDL were associated with an increased risk of all fractures. PC1 (mainly contributed by lipid subclasses of LDL and VLDL), which explained the most variance of individual biomarkers, showed a negative association with the risk of all fractures (P = 7.80E-08). Similar associations were observed for hip fracture.

CONCLUSIONS

Higher levels of large and very large HDL were associated with an increased risk of fractures, whereas higher lipid subclasses of LDL and VLDL were associated with a lower risk of fracture. Higher levels of VLDL subclasses in different lipid constituents were associated with increased BMD at multiple sites, while higher level of HDL was associated with decreased BMD.

Can AI reveal the next generation of high-impact bone genomics targets?

Genetic studies have revealed hundreds of loci associated with bone-related phenotypes, including bone mineral density (BMD) and fracture risk. However, translating discovered loci into effective new therapies remains challenging. We review success stories including PCSK9-related drugs in cardiovascular disease and evidence supporting the use of human genetics to guide drug discovery, while highlighting advances in artificial intelligence and machine learning with the potential to improve target discovery in skeletal biology. These strategies are poised to improve how we integrate diverse data types, from genetic and electronic health records data to single-cell profiles and knowledge graphs. Such emerging computational methods can position bone genomics for a future of more precise, effective treatments, ultimately improving the outcomes for patients with common and rare skeletal disorders.

Heme metabolism mediates RANKL-induced osteoclastogenesis via mitochondrial oxidative phosphorylation

Bone undergoes life-long remodeling, in which disorders of bone remodeling could occur in many pathological conditions including osteoporosis. Understanding the cellular metabolism of osteoclasts (OCs) is key to developing new treatments for osteoporosis, a disease that affects over 200 million women worldwide per annum. We found that human OC differentiation from peripheral blood mononuclear cells derived from 8 female patients is featured with a distinct gene expression profile of mitochondrial biogenesis. Elevated mitochondrial membrane potential (MMP, Δψm) was also observed in receptor activator of NF-κB ligand (RANKL)-induced OCs. Interestingly, the gene pathways of heme synthesis and metabolism were activated upon RANKL stimulation, featured by transcriptomic profiling in murine cells at a single-cell resolution, which revealed a stepwise expression pattern of heme-related genes. The real-world human data also divulges potential links between heme-related genes and bone mineral density. Heme is known to have a role in the formation of functional mitochondrial complexes that regulate MMP. Disruption of heme biosynthesis via genetically silencing Ferrochelatase or a selective inhibitor, N-methyl Protoporphyrin IX (NMPP), demonstrated potent inhibition of OC differentiation, with a dose-dependent effect observed in NMPP treatment and a substantial efficacy even at a single dose. In vivo study further showed the protective effect of NMPP on ovariectomy-induced bone loss in female mice. Collectively, we found that RANKL-mediated signaling regulated mitochondrial formation and heme metabolism to synergistically support osteoclastogenesis. Inhibition of heme synthesis impaired OC formation and reversed excessive bone loss, representing a new therapeutic target for metabolic skeletal disorders.

Shared Genetic Architecture and Causal Relationship Between Serum 25-Hydroxyvitamin D and Bone Mineral Density

CONTEXT

Despite the well-established regulatory role of vitamin D in maintaining bone health, little is known about the shared genetics and causality of the association between serum 25-hydroxyvitamin D (25OHD) and bone mineral density (BMD).

OBJECTIVE

We aimed to investigate the shared genetic architecture and causal relationship between serum 25OHD and BMD, providing insights into their underlying biological mechanisms.

METHODS

Leveraging individual-level data from the UK Biobank (UKB) cohort and summary-level data from the genome-wide association studies (GWASs) conducted on European individuals for serum 25OHD (N = 417 580) and estimated heel BMD (eBMD, N = 426 824), we systematically elucidated the shared genetic architecture underlying serum 25OHD and eBMD through a comprehensive genome-wide cross-trait design.

RESULTS

Despite a lack of global genetic correlation (rg=-0.001; P = .95), a statistically significant local signal was discovered at 5p11-5q11.9. Two-sample mendelian randomization (MR) indicated no causal association in the overall population (β=.003, 95% CI, -0.04 to 0.03; P = .93), while positive causal effects were observed in males (β=.005, 95% CI, 0.00 to 0.01; P = .03) and older individuals (β=.009, 95% CI, 0.00∼0.02; P = .01) according to one-sample MR. A total of 49 pleiotropic single-nucleotide variations (SNVs), with 4 novel SNVs (rs1077151, rs79873740, rs12150353, and rs4760401), were identified, and a total of 95 gene-tissue pairs exhibited overlap, predominantly enriched in the nervous, digestive, exocrine/endocrine, and cardiovascular systems. Protein-protein interaction analysis identified RPS9 and RPL7A as hub genes.

CONCLUSION

This study illuminates the potential health benefits of enhancing serum 25OHD levels to mitigate the risk of osteoporosis among men and individuals older than 65 years. It also unveils a shared genetic basis between serum 25OHD and eBMD, offering valuable insights into the intricate biological pathways.

Crosstalk between kidney and bones: New perspective for modulating osteoporosis

Growing evidence indicates an interesting interplay between kidney and bone. The pathophysiological condition of the skeletal system is intricately associated with the normal functioning of the kidneys. This relationship is modulated by various factors, including calcium and phosphate, 1-α-hydroxylase, erythropoietin (EPO), klotho, fibroblast growth factor 23 (FGF23), bone morphogenetic protein-7 (BMP-7), and extracellular vesicles (EVs). These interactions are notably evident in conditions such as chronic kidney disease with bone mineral density (CKD-BMD), renal osteodystrophy (ROD), and osteoporosis (OP). Furthermore, innovative methodologies such as cell co-culture, organ-on-a-chip, single-cell sequencing, and spatial transcriptomics are highlighted as instrumental in advancing the study of inter-organ interactions. This review, grounded in the pathogenesis, diagnostic and therapeutic modalities, and pharmacological treatments of OP, synthesizes evidence from molecular biology to clinical perspectives. It aims to establish a foundation for the development of more complex and physiologically relevant in vitro models and to propose potential therapeutic strategies.

Ensemble-learning approach improves fracture prediction using genomic and phenotypic data

This study presents an innovative ensemble machine learning model integrating genomic and clinical data to enhance the prediction of major osteoporotic fractures in older men. The Super Learner (SL) model achieved superior performance (AUC = 0.76, accuracy = 95.6%, sensitivity = 94.5%, specificity = 96.1%) compared to individual models. Ensemble machine learning improves fracture prediction accuracy, demonstrating the potential for personalized osteoporosis management.

PURPOSE

Existing fracture risk models have limitations in their accuracy and in integrating genomic data. This study developed and validated an innovative ensemble machine learning (ML) model that combines multiple algorithms and integrates clinical, lifestyle, skeletal, and genomic data to enhance prediction for major osteoporotic fractures (MOF) in older men.

METHODS

This study analyzed data from 5130 participants in the Osteoporotic Fractures in Men cohort Study. The model incorporated 1103 individual genome-wide significant variants and conventional risk factors of MOF. The participants were randomly divided into training (80%) and testing (20%) sets. Seven ML algorithms were combined using the SL ensemble method with tenfold cross-validation MOF prediction. Model performance was evaluated on the testing set using the area under the curve (AUC), the area under the precision-recall curve, calibration, accuracy, sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and reclassification metrics. SL model performances were evaluated by comparison with baseline models and subgroup analyses by race.

RESULTS

The SL model demonstrated the best performance with an AUC of 0.76, accuracy of 95.6%, sensitivity of 94.5%, specificity of 96.1%, NPV of 95.1%, and PPV of 94.7%. Among the individual ML, gradient boosting performed optimally. The SL model outperformed baseline models, and it also achieved accuracies of 93.1% for Whites and 91.6% for Minorities, outperforming single ML in subgroup analysis.

CONCLUSION

The ensemble learning approach significantly improved fracture prediction accuracy and model performance compared to individual ML. Integrating genomic and phenotypic data via the SL approach represents a promising advancement for personalized osteoporosis management.

Re-engineering bone: pathogenesis, diagnosis and emerging therapies for osteoporosis

Osteoporosis, a multifaceted metabolic bone disease, is becoming increasingly prevalent and poses a significant burden on global healthcare systems. Given the limitations of traditional treatments such as pharmacotherapy, tissue engineering has emerged as a promising alternative for osteoporosis management. This review begins by exploring the pathogenesis of osteoporosis, with a focus on the abnormal metabolic, cellular, and molecular signalling microenvironments that drive the disease. We also examine commonly used clinical diagnostic techniques, discussing their strengths and limitations. Notably, this review evaluates various advanced tissue engineering strategies for osteoporosis treatment. Delivery systems, including injectable hydrogels and nanomaterials, are detailed alongside bone tissue engineering materials such as bioactive ceramics, bone cements, and polymers. Additionally, biologically active substances, including exosomes and cytokines, and emerging therapies that leverage small-molecule drugs are explored. Through a comprehensive analysis of the advantages and limitations of current biomaterials and therapeutic approaches, this review provides insights into future directions for tissue engineering-based solutions. By synthesizing current advancements, it aims to inspire innovative perspectives for the clinical management of osteoporosis.

Prevalence and predictors of low bone mineral density in pediatric inflammatory bowel disease

OBJECTIVES

Bone health is at risk in children with inflammatory bowel disease (IBD). This study examined the prevalence and predictors of low bone mineral density (BMD) in a cohort of children and young adults with IBD.

METHODS

This single-center retrospective study included patients with IBD, ages 3.5-22 years, with completed dual x-ray absorptiometry (DXA) scans from 2006 to 2019. Demographic, clinical, and laboratory data were collected. Logistic regression analysis identified predictors associated with low BMD (Z-scores ≤ -2 standard deviations [SDs]) for three outcomes. In an overlapping IBD cohort with available genetic data between 2002 and 2019 (n = 378), genetic risk for diminished bone health was calculated using published polygenic risk scores generated from genome-wide association studies based on DXA or heel ultrasound speed of sound (SOS). Linear regression analysis examined associations of low BMD and genetic risk.

RESULTS

Low BMD prevalence was 7% in our cohort (n = 600) based on spine bone mineral apparent density (BMAD), which best accounts for growth delays. Median (interquartile range [IQR]) spine BMAD Z-score was -0.37 SD (-1.11 to 0.35). Predictors of low BMAD included lower BMI Z-score (odds ratio [OR]: 0.67, p value: 0.02) and decreased height Z-score (OR: 0.6, p value: 0.005). Of those with longitudinal data (n = 118), low BMI (OR: 0.44, p value: <0.001) and steroid use (OR: 3.42, p value: 0.01) were associated with suboptimal bone health (Z-scores ≤ -1SD). In the cohort with genetic data, heel genomic SOS (β [standard error] = 0.17 [0.35], p ≤ 0.01) was associated with BMD.

CONCLUSIONS

Lower BMI should prompt DXA monitoring in pediatric IBD. Genetic predisposition may identify an at-risk subpopulation.

The research progress on radionuclides in osteoporosis diagnosis and drug efficacy monitoring

Osteoporosis is a common metabolic bone disease that seriously affects the quality of life and health of patients. Traditional diagnostic methods, such as dual energy X-ray absorptiometry (DXA), have limitations in early detection and dynamic monitoring, making it difficult to meet clinical needs. This paper focuses on the potential of radionuclide imaging techniques, such as Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET), in the early diagnosis of osteoporosis. The paper further elaborates on the importance of radionuclides in evaluating the therapeutic effect of osteoporosis drugs. By summarizing current research findings, this paper aims to emphasize the core role of radionuclides in the management of osteoporosis, and provide theoretical basis and practical guidance for optimizing the diagnosis and treatment strategies of bone metabolism diseases in the future.

Mapping the role of macro and micronutrients in bone mineral density: a comprehensive Mendelian randomization study

BACKGROUND

Macro and micronutrients may play an important role in osteoporosis development; however, observational studies have yielded inconsistent results. Clarifying these associations is vital to the development of nutritional recommendations aimed at preventing osteoporosis.

METHODS

Utilizing the largest available genome-wide association study (GWAS) summary statistics to date, we performed a two-sample Mendelian randomization (MR) analysis to investigate the causal effects of energy-adjusted macronutrient intake (fat, protein, carbohydrate, and sugar) and circulating levels of 20 micronutrients (ten each for vitamins and minerals) on heel estimated bone mineral density (eBMD), a promising marker for osteoporosis risk and fracture susceptibility. Sensitivity, sex-specific, and one-sample MR analyses were applied to further validate and annotate the results.

RESULTS

Among all nutrients, four genetically predicted circulating levels of micronutrients were suggestively associated with eBMD (vitamin A: β IVW = - 0.054, PIVW = 3.70 × 10-2; vitamin B12: β IVW = - 0.020, PIVW = 3.71 × 10-6; vitamin E: β IVW = 0.277, PIVW = 3.22 × 10-2; selenium: β IVW = 0.023, PIVW = 5.37 × 10-3; all Pintercept > 0.05). All these results were also considered robust, as sensitivity analyses yielded directionally consistent results. However, only the causal effects of vitamin B12 and selenium on eBMD remained significant after Bonferroni correction and were not confounded by obesity, smoking status, or alcohol consumption. Sex-specific analysis revealed a male-specific causal association between vitamin E and eBMD ( β IVW = 0.275, PIVW = 9.81 × 10-14). Additionally, using individuallevel data from the UK Biobank cohort, one-sample MR analysis found no causal relationships between diet-derived nutrient intake and eBMD in the overall population, as well as in the females or the males.

CONCLUSIONS

Our findings suggest that appropriate levels of plasma vitamin B12 and adequate levels of serum selenium are crucial for delaying bone loss and promoting bone health, emphasizing the need for nutritional recommendations to maintain optimal levels of these nutrients to promote eBMD and prevent osteoporosis.

The Role of Sex Steroid Hormones in the Association Between Manganese Exposure and Bone Mineral Density: National Health and Nutrition Examination Survey 2013-2018

This study investigates the association between blood Mn and bone mineral density (BMD), focusing on the mediating role of sex steroids, using data from 8617 participants in the National Health and Nutrition Examination Survey (NHANES) 2013-2018. Weighted multiple linear regression models were used to examine the association of blood Mn and total BMD, and mediation analyses were used to explored the roles of total testosterone (TT), estradiol (E2), and sex hormone-binding globulin (SHBG) in the Mn-BMD relationship, stratified by sex and menopausal status. Blood Mn was negatively associated with BMD in both sexes, with a pronounced effect in postmenopausal women. SHBG mediated 37.16% of the Mn-BMD association in men, whereas no mediating effects were found in women. E2 exhibited a significant indirect effect, suggesting that reduced E2 levels may amplify Mn's effect on BMD. These findings indicate that Mn exposure is associated with decreased BMD, potentially through alterations in sex steroids, highlighting the importance of considering hormone status when evaluating the impact of Mn exposure on BMD.

Gastroesophageal reflux disease and osteoporosis: A bidirectional Mendelian randomization study

In observational studies, associations between osteoporosis (OP) and gastroesophageal reflux disease (GERD) have been found. We conducted a 2-way, 2-sample Mendelian randomization (MR) analysis to determine whether these associations have a causal relationship. Data on GERD at the summary-level were sourced from extensive genome-wide association studies encompassing 129,080 cases and 473,524 control subjects. Bone mineral density (BMD) served as the phenotypic indicator for OP. BMD metrics were compiled from a cohort of 537,750 individuals, encompassing total body BMD (TB-BMD) and stratified TB-BMD across age groups, along with BMD measurements at 4 anatomical locations: lumbar spine, femoral neck, heel, and ultra-distal forearm. Multiple MR approaches, such as the inverse-variance weighted (IVW) method, MR-Egger regression, and the MR-PRESSO test, were employed, among which findings obtained by IVW method were designated as the primary outcomes. For quality assurance, sensitivity analyses were conducted using the MR-Egger intercept, Cochran Q, and leave-one-out test. There were no significant causal links between genetic inclination towards GERD and reduced BMD levels. Nonetheless, the genetic evidence suggests a causal link between higher BMD levels and lower incidence of GERD [TB-BMD: OR = 0.941, 95% confidence intervals (CI) = 0.910-0.972, P < .001; TB-BMD-1: OR = 0.919, 95% CI = 0.885-0.954, P < .001; TB-BMD-3: OR = 0.945, 95% CI = 0.915-0.977, P = .001; TB-BMD-4: OR = 0.926, 95% CI = 0.896-0.957, P < .001]. Sensitivity analyses corroborate our findings. The MR analysis indicates no significant causal link between genetic inclination towards GERD and OP or reduced BMD within the European demographic. In addition, the study suggests that lower BMD or OP, as predicted by genetics, may contribute to the development of GERD.

Causal Associations of Inflammatory Cytokines With Osteosarcopenia: Insights From Mendelian Randomization and Single Cell Analysis

Background: Osteosarcopenia, the coexistence of osteoporosis and sarcopenia, poses significant challenges in aging populations due to its dual impact on bone and muscle health. Inflammation, mediated by specific cytokines, is thought to play a crucial role in the development of osteosarcopenia, though the underlying mechanisms are not fully understood. Objective: This study aimed to clarify the causal role of circulating cytokines in the pathogenesis of osteosarcopenia by employing mendelian randomization (MR) and single-cell RNA sequencing (scRNA-seq) to identify cell-specific cytokine expression patterns. The ultimate objective was to uncover potential pathological mechanisms and therapeutic targets for treating osteosarcopenia. Methods: A two-sample MR approach was employed, leveraging publicly available genome-wide association study (GWAS) data from multiple cohorts. A total of 91 circulating cytokines were examined using genetic instruments, and their causal effects on traits related to osteoporosis and sarcopenia were evaluated. Various complementary and sensitivity analyses were performed to ensure robust findings. Additionally, scRNA-seq datasets from human muscle and bone marrow were analyzed to validate the single-cell expression profiles of candidate cytokines. Results: MR analysis identified several cytokines with causal effects on osteosarcopenia traits, including LTA, CD40, CXCL6, CXCL10, DNER (delta and notch-like epidermal growth factor-related receptor), and VEGFA (vascular endothelial growth factor A). LTA and CD40 were protective for both bone and muscle, while VEGFA posed a risk. Other cytokines demonstrated opposite effects on bone and muscle. Single cell analysis revealed distinct expression patterns, with LTA highly expressed in lymphocytes, CD40 in immune cells, and VEGFA in various musculoskeletal cell types. Age-related differences in cytokine expression were also noted, with LTA more highly expressed in younger individuals, and VEGFA in older individuals. Conclusion: This study offers preliminary insights into the inflammatory mechanisms potentially driving osteosarcopenia, identifying key cytokines that may be involved in its pathogenesis. By integrating MR and scRNA-seq data, we highlight potential therapeutic targets, though further research is needed to confirm these findings and their implications for musculoskeletal health.

The causal relationship of inflammation-related factors with osteoporosis: A Mendelian Randomization Analysis

BACKGROUND

We used Mendelian randomization (MR) approach to examine whether genetically determined inflammation-related risk factors play a role in the onset of osteoporosis (OP) in the European population.

METHODS

Genome-wide association studies (GWASs) summary statistics of estimated bone mineral density (eBMD) obtained from the public database GEnetic Factors for OSteoporosis Consortium (GEFOS) including 142,487 European people. For exposures, we utilized GWAS data of 9 risk factors including diseases chronic kidney disease (CKD) (41,395 cases and 439,303 controls), type 2 diabetes (T2D) (88,427 cases and 566,778 controls), Alzheimer's disease (AD) (71,880 cases, 383,378 controls) and major depression disorder (MDD) (9240 cases and 9519 controls) and lifestyle behaviors are from different consortiums. Inverse variance weighted (IVW) analysis was principal method in this study and random effect model was applied; MR-Egger method and weighted median method were also performed for reliable results. Cochran's Q test and MR-Egger regression were used to detect heterogeneity and pleiotropy and leave-one-out analysis was performed to find out whether there are influential SNPs.

RESULTS

We found that T2D (IVW: β = 0.05, P = 0.0014), FI (IVW: β = -0.22, P < 0.001), CKD (IVW: β = 0.02, P = 0.009), ALZ (IVW: β = 0.06, P = 0.005), Coffee consumption (IVW: β = 0.11, P = 0.003) were causally associated with OP (P<0.006after Bonferroni correction).

CONCLUSIONS

Our study revealed that T2D, FI, CKD, ALZ and coffee consumption are causally associated with OP. Future interventions targeting factors above could provide new clinical strategies for the personalized prevention and treatment of osteoporosis.

A multi-ancestry GWAS meta-analysis of facial features and its application in predicting archaic human features

Facial morphology, a complex trait influenced by genetics, holds great significance in evolutionary research. However, due to limited fossil evidence, the facial characteristics of Neanderthals and Denisovans have remained largely unknown. In this study, we conduct a large-scale multi-ethnic meta-analysis of the genome-wide association study (GWAS), including 9674 East Asians and 10,115 Europeans, quantitatively assessing 78 facial traits using 3D facial images. We identify 71 genomic loci associated with facial features, including 21 novel loci. We develop a facial polygenic score (FPS) that enables the prediction of facial features based on genetic information. Interestingly, the distribution of FPSs among populations from diverse continental groups exhibits relevant correlations with observed facial features. Furthermore, we apply the FPS to predict the facial traits of seven Neanderthals and one Denisovan using ancient DNA and align predictions with the fossil records. Our results suggest that Neanderthals and Denisovans likely share similar facial features, such as a wider but shorter nose and a wider endocanthion distance. The decreased mouth width is characterized specifically in Denisovans. The integration of genomic data and facial trait analysis provides valuable insights into the evolutionary history and adaptive changes in human facial morphology.

How Accurately Does Bone Mineral Density Predict Bone Strength? A Clinical Observational Study of Osteoporosis Vertebral Compression Fractures in Postmenopausal Women

OBJECTIVES

Dual energy x-ray absorptiometry (DXA) provides incomplete information about bone strength. There are few data on the relationship between osteoporosis-related examinations and bone strength. The objective of the present study was to determine which osteoporosis-related examinations best predicted trabecular bone strength, and to enhance a formula for predicting bone strength on the basis of bone density examination.

METHODS

This observational study included postmenopausal women (aged over 50 years) who underwent unilateral percutaneous kyphoplasty (PKP) surgery in the lumbar spine between September 2021 and June 2023. The pressure within each balloon expansion circle was extracted to reflect the true bone strength. The NHANES 2013-2014 data were used to assess the performance of the formula. The performance of the formula was compared with that of the observed actual fractures. Bland-Altman analysis was used to compare the agreement between the formula and the fracture risk assessment tool (FRAX) score.

RESULTS

A total of 40 postmenopausal women (mean age ± standard deviation, 70.90 years ± 10.30) were enrolled. The average balloon pressure was 59.23 psi (± 12.40, means ± SDs). The mean BMD of total lumbar spine (average of L1-L4) was 0.89 g/cm2 ± 0.20 (mean ± standard), and the Pearson correlation coefficient between lumbar BMD and bone strength was 0.516. After adjusting for age and BMI, the DXA response rate to bone strength reached 72%. Calibration plots of the observed actual fractures versus those estimated via the bone strength formula were considered good fits. The Bland-Altman analysis revealed a nonsignificant difference between the formula and the FRAX score in predicting fracture risk.

CONCLUSIONS

After adjustment, the DXA response rate to bone strength reached 72%, indicating a strong correlation. In addition, Bone Strength = DXA × 27 - Age × 0.585-BMI × 0.887 + 98.

Identifying rare variants in genes related to bone phenotypes in a cohort of postmenopausal women

Rare genetic variants in genes previously described to be involved in bone monogenic disorders were identified in postmenopausal women split into two groups according to extreme bone mineral density (BMD) values and lumbar spine Z-scores. A pathogenic variant in COL1A2 gene found in a woman with low BMD highlights the overlap between osteogenesis imperfecta and osteoporosis, which may share their genetic etiology. Other variants were not clearly associated with the extreme BMD, suggesting that there is little contribution of rare variants to postmenopausal osteoporosis.

PURPOSE

We aimed to evaluate whether extreme values of bone mineral density (BMD) in a population-based cohort of postmenopausal women (BARCOS) could be determined by rare genetic variants in genes related to monogenic bone disorders.

METHODS

A panel of 127 genes related to different skeletal phenotypes was designed. Massive sequencing by targeted capture of these genes was performed in 104 DNA samples from those women of the BARCOS cohort that exhibited the highest (HZ group) and lowest (LZ group) LS Z-scores, ranging from + 0.70 to + 3.80 and from - 2.35 to - 4.26, respectively. 5'UTR, 3'UTR, splice region, missense, nonsense, and short indel variants with MAF < 0.01 were annotated with CADD version 1.6 and considered in the analysis.

RESULTS

After filtering those variants with CADD > 25 and present only in one of the groups (either LZ or HZ), six variants were detected, most of which (5/6) were in the LZ group in TCIRG1, COL1A2, SEC24D, LRP4, and ANO5 genes, while only one, in the LMNA gene, was in the HZ group. According to the ClinVar database, the COL1A2 variant, causative of a recessive form of osteogenesis imperfecta, is described as pathogenic, while the other variants are considered of uncertain significance (VUS).

CONCLUSION

The variant identified in COL1A2 in a woman from the LZ group highlights the genetic overlap between monogenic diseases such as osteogenesis imperfecta and complex diseases like osteoporosis. However, the other variants were not clearly associated with the extreme BMD, suggesting that there is little contribution of rare variants to postmenopausal osteoporosis.

Genetic analysis of cis-enhancers associated with bone mineral density and periodontitis in the gene SOST

A haplotype block at the sclerostin (SOST) gene correlates with bone mineral density (BMD) and increased periodontitis risk in smokers. Investigating the putative causal variants within this block, our study aimed to elucidate the impact of linked enhancer elements on gene expression and to evaluate their role in transcription factor (TF) binding. Using CRISPR/dCas9 activation (CRISPRa) screening in SaOS-2 cells, we quantified disease-related enhancer activities regulating SOST expression. Additionally, in SaOS-2 cells, we investigated the influence of the candidate TFs CCAAT/enhancer-binding protein beta (CEBPB) on gene expression by antisense (GapmeR) knockdown, followed by RNA sequencing. The periodontitis-linked SNP rs9783823 displayed a significant cis-activating effect (25-fold change in SOST expression), with the C-allele containing a CEBPB binding motif (position weight matrix (PWM) =  0.98, Pcorrected =  7.7 x 10-7). CEBPB knockdown induced genome-wide upregulation but decreased epithelial-mesenchymal transition genes (P =  0.71, AUC =  2.2 x 10-11). This study identifies a robust SOST cis-activating element linked to BMD and periodontitis, carrying CEBPB binding sites, and highlights CEBPB's impact on epithelial-mesenchymal transition.

Regulation of WNT16 in bone may involve upstream enhancers within CPED1

WNT16 stands up as an essential gene for bone homeostasis. Here, we present new evidence of the functional role of a particular region within WNT16. Performing 4 C chromatin conformation analysis in three osteoblast-related cells (the human fetal osteoblast hFOB 1.19 cell line, Saos 2 osteosarcoma cell line and mesenchymal Stem Cells -MSC-), we identify physical interactions between the proximal part of WNT16 intron 2, shown here to be an active promoter in Saos 2 osteosarcoma cells, and several putative regulatory regions within CPED1. Analysis of previously published RNA-seq data from hFOB cells disclosed low expression of a region located downstream of this promoter. Our results suggest a novel regulatory mechanism of WNT16 in bone, mediated by physical interaction with various enhancer regions within CPED1.

Enhanced insights into the genetic architecture of 3D cranial vault shape using pleiotropy-informed GWAS

Large-scale GWAS studies have uncovered hundreds of genomic loci linked to facial and brain shape variation, but only tens associated with cranial vault shape, a largely overlooked aspect of the craniofacial complex. Surrounding the neocortex, the cranial vault plays a central role during craniofacial development and understanding its genetics are pivotal for understanding craniofacial conditions. Experimental biology and prior genetic studies have generated a wealth of knowledge that presents opportunities to aid further genetic discovery efforts. Here, we use the conditional FDR method to leverage GWAS data of facial shape, brain shape, and bone mineral density to enhance SNP discovery for cranial vault shape. This approach identified 120 independent genomic loci at 1% FDR, nearly tripling the number discovered through unconditioned analysis and implicating crucial craniofacial transcription factors and signaling pathways. These results significantly advance our genetic understanding of cranial vault shape and craniofacial development more broadly.

From teeth to bone: dental caries has causal effects on osteoporosis and osteoporotic fracture

OBJECTIVES

Evidence from observational studies suggested oral diseases (periodontitis (PD) and dental caries) may increase susceptibility to bone loss. However, inherent confounding of observational studies limits causal interpretation. We aimed to conduct Mendelian randomization (MR) analysis to estimate the causal effect of oral diseases on osteoporosis (OP), bone mineral density (BMD) and fracture risk.

METHODS

We used summary-level GWAS meta-analysis data from the GLIDE consortium to identify 7 and 17 single-nucleotide polymorphisms (SNPs) for periodontitis and DMFS (the sum of Decayed, Missing, and Filled tooth Surfaces) as the instrumental variables. MR analyses of these instruments were performed on European individuals for the association with BMD of forearm, femoral neck and lumbar spine; and individuals from FinnGen consortium for OP, OP with pathological fracture, postmenopausal OP with pathological fracture, and site-specific fractures. We performed single-variable Mendelian randomization (SVMR) and multivariable Mendelian randomization (MVMR) to simultaneously assess independent causal effects of PD and DMFS on different outcomes. The estimates were primarily derived using inverse variance weighted (IVW) methods. Sensitivity analyses included weighted median, MR-egger, and Leave-one-out test.

RESULTS

In MVMR, after adjusting for PD, DMFS has a positive causal effect osteoporosis (OR = 1.165, [95% CI 1.020 to 1.331, P = 0.025]) and postmenopausal OP with pathological fracture (OR = 1.422, [95% CI 1.027 to 1.969, P = 0.034]). However, these causal relationships were not observed in the single-variable Mendelian randomization (SVMR) analysis. The causal associations were robust in various sensitivity analyses.

CONCLUSIONS

In conclusion, dental caries causally increases the risk of OP and postmenopausal OP with pathological fracture, suggesting the existence of teeth-bone axis. Proactive osteoporosis screening in patients with severe dental caries may be warranted for clinical consideration.

Cardio-metabolic-related plasma proteins reveal biological links between cardiovascular diseases and fragility fractures: a cohort and Mendelian randomisation investigation

BACKGROUND

How cardiovascular diseases (CVD) predispose to a higher risk of fragility fractures is not well understood. Both contribute to significant components of disease burden and health expenditure. Poor bone quality, central obesity, sarcopenia, falls, and low grip strength are independent risk factors for hip and other fragility fractures and also for CVD and early death.

METHODS

We used proteomics and a cohort design combined with Mendelian randomisation analysis to understand shared mechanisms for developing CVD and fragility fractures, two significant sources of disease burden and health expenditure. We primarily aimed to discover and replicate the association of 274 cardio-metabolic-related proteins with future rates of hip and any fracture in two separate population-based cohorts, with a total of 12,314 women and men.

FINDINGS

The average age at baseline was 68 years in the discovery cohort of women and 74 years in the mixed-sex replication cohort. During 100,619 person-years of follow-up, 2168 had any fracture, and 538 had a hip fracture. Our analysis resulted in 24 cardiometabolic proteins associated with fracture risk: 20 with hip fracture, 9 with any fracture, and 5 with both. The associations remained even if protein concentrations were measured from specimens taken during preclinical stages of cardio-metabolic diseases, and 19 associations remained after adjustment for bone mineral density. Twenty-two of the proteins were associated with total body fat mass or lean body mass. Mendelian randomisation (MR) analysis supported causality since genetically predicted levels of SOST (Sclerostin), CCDC80 (Coiled-coil domain-containing protein 80), NT-proBNP (N-terminal prohormone brain natriuretic peptide), and BNP (Brain natriuretic peptide) were associated with risk of hip fracture. MR analysis also revealed a possible negative impact on bone mineral density (BMD) by genetically predicted higher levels of SOST, CCDC80, and TIMP4 (Metalloproteinase inhibitor 4). The MR association with BMD was positive for PTX3 (Pentraxin-related protein) and SPP1 (Osteopontin). Genetically predicted higher concentrations of SOST and lower concentrations of SPP1 also conferred a higher risk of falls and lowered grip strength. The genetically determined concentration of nine proteins influenced fat mass, and one influenced lean body mass.

INTERPRETATION

These data reveal biological links between cardiovascular diseases and fragility fractures. The proteins should be further evaluated as shared targets for developing pharmacological interventions to prevent fractures and cardiovascular disease.

FUNDING

The study was supported by funding from the Swedish Research Council (https://www.vr.se; grants No. 2015-03257, 2017-00644, 2017-06100, and 2019-01291 to Karl Michaëlsson) and funding from Olle Engkvist Byggmästares stiftelse (SOEB).

Characterization of gene-environment interactions for vitamin D through variance quantitative trait loci: a UK Biobank-based genetic epidemiology study

BACKGROUND

Understanding gene-environment interactions associated with vitamin D status may refine nutrition and public health strategies for vitamin D deficiency. Recent methodological advances have enabled the identification of variance quantitative trait loci (vQTLs) where gene-environment interactions are enriched.

OBJECTIVES

The study aims to identify vQTLs for serum 25-hydroxy vitamin D (25OHD) concentrations and characterize potential gene-environment interactions of vQTLs.

METHODS

We conducted vQTL discovery for 25OHD using a newly developed quantile integral linear model in the UK Biobank individuals of European (N = 313,514), African (N = 7800), East Asian (N = 2146), and South Asian (N = 8771) ancestries, respectively. We tested for interactions between the identified vQTL lead variants and 18 environmental, biological, or lifestyle factors, followed by multiple sensitivity analyses.

RESULTS

We identified 19 independent vQTL lead variants (P < 5 × 10-8) in the European ancestry population. No vQTLs were identified in the non-European ancestry populations, likely because of limited sample sizes. A total of 32 interactions were detected with a false discovery rate <0.05. Although known gene-season of measurement interactions were confirmed, additional interactions were identified involving modifiable risk factors, including time spent outdoors and body mass index. The magnitudes of these interactions were consistent within each locus upon adjusting for the season of measurement and other covariates. We also identified a gene-sex interaction at a vQTL that implicates DHCR7. Integrating transcript- and protein-level evidence, we found that the sex-differentiated genetic associations may act through sex-biased expression of DHCR7 isoforms in skin tissues because of alternative splicing.

CONCLUSIONS

Through the lens of vQTLs, we identified additional gene-environment interactions affecting vitamin D status in addition to the season of measurement. These findings may provide new insights into the etiology of vitamin D deficiency and encourage personalized prevention and management of associated diseases for at-risk individuals.

LRP5 promotes adipose progenitor cell fitness and adipocyte insulin sensitivity

BACKGROUND

WNT signaling plays a key role in postnatal bone formation. Individuals with gain-of-function mutations in the WNT co-receptor LRP5 exhibit increased lower-body fat mass and potentially enhanced glucose metabolism, alongside high bone mass. However, the mechanisms by which LRP5 regulates fat distribution and its effects on systemic metabolism remain unclear. This study aims to explore the role of LRP5 in adipose tissue biology and its impact on metabolism.

METHODS

Metabolic assessments and imaging were conducted on individuals with gain- and loss-of-function LRP5 mutations, along with age- and BMI-matched controls. Mendelian randomization analyses were used to investigate the relationship between bone, fat distribution, and systemic metabolism. Functional studies and RNA sequencing were performed on abdominal and gluteal adipose cells with LRP5 knockdown.

RESULTS

Here we show that LRP5 promotes lower-body fat distribution and enhances systemic and adipocyte insulin sensitivity through cell-autonomous mechanisms, independent of its bone-related functions. LRP5 supports adipose progenitor cell function by activating WNT/β-catenin signaling and preserving valosin-containing protein (VCP)-mediated proteostasis. LRP5 expression in adipose progenitors declines with age, but gain-of-function LRP5 variants protect against age-related fat loss in the lower body.

CONCLUSIONS

Our findings underscore the critical role of LRP5 in regulating lower-body fat distribution and insulin sensitivity, independent of its effects on bone. Pharmacological activation of LRP5 in adipose tissue may offer a promising strategy to prevent age-related fat redistribution and metabolic disorders.

A multiparametric anti-aging CRISPR screen uncovers a role for BAF in protein synthesis regulation

Progeria syndromes are very rare, incurable premature aging conditions recapitulating most aging features. Here, we report a whole genome, multiparametric CRISPR screen, identifying 43 genes that can rescue multiple cellular phenotypes associated with progeria. We implement the screen in fibroblasts from Néstor-Guillermo Progeria Syndrome male patients, carrying a homozygous A12T mutation in BAF. The hits are enriched for genes involved in protein synthesis, protein and RNA transport and osteoclast formation and are validated in a whole-organism Caenorhabditis elegans model. We further confirm that BAF A12T can disrupt protein synthesis rate and fidelity, which could contribute to premature aging in patients. This work highlights the power of multiparametric genome-wide suppressor screens to identify genes enhancing cellular resilience in premature aging and provide insights into the biology underlying progeria-associated cellular dysfunction.

Genomic correlation, shared loci, and causal association between obesity, periodontitis and tooth loss

Observational studies have reported an association of obesity with periodontitis and tooth loss, yet findings remain inconsistent. We aim to investigate the genetic link underlying obesity-related traits (BMI [body mass index], WHR [waist-to-hip ratio], WHRadjBMI and childhood BMI), periodontitis and tooth loss. Leveraging summary statistics from large-scale genome-wide association studies, we comprehensively investigated the pair-wise genetic correlation using linkage disequilibrium score regression (LDSC) and SUPERGNOVA, identified shared loci using cross-phenotype association analysis (CPASSOC), and estimated causal association using Mendelian randomization. We identified a significant genetic correlation of obesity with tooth loss, but not with periodontitis. Partitioning the genome into LD-independent regions revealed 10 significantly shared local signals across six regions. Genome-wide cross-trait analysis uncovered 14 shared loci, four of which were colocalized: rs2064044 (PP4 = 0.94), rs6000329 (PP4 = 0.86), rs7134628 (PP4 = 0.86), and rs1286769 (PP4 = 0.90). Notably, rs1286769, identified via CPASSOC and validated through colocalization analysis, is located near RARβ, a gene associated with both BMI and denture use. Mendelian randomization revealed a nominally-significant causal association of obesity with periodontitis (P = 0.045) but a robust causal association with tooth loss represented by number of teeth (BMI: beta = [Formula: see text]0.20, 95%CI = [Formula: see text]0.26 to [Formula: see text]0.14, P = 5.27 × 10-11; WHR: beta = [Formula: see text]0.16, 95%CI = [Formula: see text]0.24 to [Formula: see text]0.08, P = 3.71 × 10-5). Results of CAUSE were consistent with main findings. From a genetic perspective, our work highlights an intrinsic link between obesity, periodontitis and tooth loss, which may add new lines of evidence and provide insights for clinical and public oral health applications.

The mediating role of thyroid-related hormones between thyroid dysfunction diseases and osteoporosis: a mediation mendelian randomization study

The links between Thyroid dysfunction diseases (TDFDs) and osteoporosis (OP) has received widespread attention, but the causal relationships and mediating factors have not been systematically studied. We used two-sample Mendelian randomization (MR) analysis to elucidate the causal relationship between TDFDs and OP. Moreover, we performed mediation MR analyses to explore the role of thyroid-related hormones and OP risk factors in the association between TDFDs and OP. Two sample MR analyses showed that hyperthyroidism increased OP (OR = 1.080, 95% CI 1.026 to 1.137; P = 0.0032) risk. Hypothyroidism increases OP (OR = 1.183, 95% CI 1.125 to 1.244; P < 0.0001) risk. Furthermore, mediation analysis revealed that TSH mediated 5.314% of the relationship between hypothyroidism and OP. In contrast, FT4 mediated 9.670% of the relationship between hyperthyroidism and OP. In European populations, TDFDs may increase OP risk. TSH mediates in the causal association between hypothyroidism and OP, and similarly, FT4 mediates in the causal link between hyperthyroidism and OP. Our findings underscore the significance of improving integrative care for individuals with TDFDs to mitigate the risk of OP. It is essential to maintain stable levels of thyroid hormones and closely monitor bone health to effectively mitigate and prevent OP.

The genetic architecture of hip shape and its role in the development of hip osteoarthritis and fracture

OBJECTIVES

Hip shape is thought to be an important causal risk factor for hip osteoarthritis and fracture. We aimed to identify genetic determinants of hip shape and use these to assess causal relationships with hip osteoarthritis.

METHODS

Statistical hip shape modelling was used to derive 10 hip shape modes (HSMs) from DXA images in UK Biobank and Shanghai Changfeng cohorts (ntotal = 43 485). Genome-wide association study meta-analyses were conducted for each HSM. Two-sample Mendelian randomisation (MR) was used to estimate causal effects between HSM and hip osteoarthritis using hip fracture as a positive control.

RESULTS

Analysis of the first 10 HSMs identified 203 independent association signals (P < 5 × 10-9). Hip shape SNPs were also associated (P < 2.5 × 10-4) with hip osteoarthritis (n = 26) and hip fracture (n = 4). Fine mapping implicated SMAD3 and PLEC as candidate genes that may be involved in the development of hip shape and hip osteoarthritis. MR analyses suggested there was no causal effect between any HSM and hip osteoarthritis, however there was evidence that HSM2 (more obtuse neck-shaft angle) and HSM4 (wider femoral neck) have a causal effect on hip fracture (ORIVW method 1.27 [95% CI 1.12-1.44], P = 1.79 × 10-4 and ORIVW 0.74 [0.65-0.84], P = 7.60 × 10-6 respectively).

CONCLUSIONS

We report the largest hip shape GWAS meta-analysis that identifies hundreds of novel loci, some of which are also associated with hip osteoarthritis and hip fracture. MR analyses suggest hip shape may not cause hip osteoarthritis but is implicated in hip fractures. Consequently, interventions targeting hip shape in older adults to prevent hip osteoarthritis may prove ineffective.

Early-life tobacco smoke elevating later-life osteoporosis risk: Mediated by telomere length and interplayed with genetic predisposition

INTRODUCTION

The growing prevalence of osteoporosis (OP) in an aging global population presents a significant public health concern. Tobacco smoke negatively affects bone turnover, leading to reduced bone mass and heightened OP and fracture risk. However, the impact of early-life tobacco smoke exposure on later-life OP risk remains unclear.

OBJECTIVES

This study was to explore the effects of early-life tobacco smoke exposure on incident OP risk in later life. The mediating role of telomere length (TL) and the interaction with genetic predisposition were also studied.

METHODS

Data on in utero tobacco smoke exposure (IUTSE) status and age of tobacco use initiation from the UK Biobank were used to estimate early-life tobacco smoke exposure. Incident OP cases were identified according to health-related records. Linear, Cox, and Laplace regression models were mainly used for data analysis.

RESULTS

Individuals with IUTSE showed a higher OP risk [hazard ratio (HR): 1.06, 95 % confidence interval (CI): 1.01, 1.11] and experienced earlier OP onset by 0.30 years [50th percentile difference = -0.30, 95 % CI: -0.51, -0.09] compared to those without. Participants initiating tobacco smoke in childhood, adolescence, and adulthood had 1.41 times (95 % CI: 1.23, 1.61), 1.17 times (95 % CI:1.10, 1.24), and 1.14 times (95 % CI: 1.07, 1.20) the risk of OP, respectively, compared to never smokers. They also experienced earlier OP onset by 2.16, 0.95, and 0.71 years, sequentially. The TL significantly mediated the early-life tobacco exposure and OP association. Significant joint and interactive effects were detected between early-life tobacco smoke exposure and genetic elements.

CONCLUSIONS

Our findings implicate that early-life tobacco smoke exposure elevates the later-life OP risk, mediated by telomere length and interplayed with genetic predisposition. These findings highlight the importance of early-life intervention against tobacco smoke exposure and ageing status for precise OP prevention, especially in individuals with a high genetic risk.

Loss of cped1 does not affect bone and lean tissue in zebrafish

Human genetic studies have nominated cadherin-like and PC-esterase domain-containing 1 (CPED1) as a candidate target gene mediating bone mineral density (BMD) and fracture risk heritability. Recent efforts to define the role of CPED1 in bone in mouse and human models have revealed complex alternative splicing and inconsistent results arising from gene targeting, making its function in bone difficult to interpret. To better understand the role of CPED1 in adult bone mass and morphology, we conducted a comprehensive genetic and phenotypic analysis of cped1 in zebrafish, an emerging model for bone and mineral research. We analyzed two different cped1 mutant lines and performed deep phenotyping to characterize more than 200 measures of adult vertebral, craniofacial, and lean tissue morphology. We also examined alternative splicing of zebrafish cped1 and gene expression in various cell/tissue types. Our studies fail to support an essential role of cped1 in adult zebrafish bone. Specifically, homozygous mutants for both cped1 mutant alleles, which are expected to result in loss-of-function and impact all cped1 isoforms, exhibited no significant differences in the measures examined when compared to their respective wildtype controls, suggesting that cped1 does not significantly contribute to these traits. We identified sequence differences in critical residues of the catalytic triad between the zebrafish and mouse orthologs of CPED1, suggesting that differences in key residues, as well as distinct alternative splicing, could underlie different functions of CPED1 orthologs in the two species. Our studies fail to support a requirement of cped1 in zebrafish bone and lean tissue, adding to evidence that variants at 7q31.31 can act independently of CPED1 to influence BMD and fracture risk.

RUNX2 Phase Separation Mediates Long-Range Regulation Between Osteoporosis-Susceptibility Variant and XCR1 to Promote Osteoblast Differentiation

GWASs have identified many loci associated with osteoporosis, but the underlying genetic regulatory mechanisms and the potential drug target need to be explored. Here, a new regulatory mechanism is found that a GWAS intergenic SNP (rs4683184) functions as an enhancer to influence the binding affinity of transcription factor RUNX2, whose phase separation can mediate the long-range chromatin interaction between enhancer and target gene XCR1 (a member of the GPCR family), leading to changes of XCR1 expression and osteoblast differentiation. Bone-targeting AAV of Xcr1 can improve bone formation in osteoporosis mice, suggesting that XCR1 can be a new susceptibility gene for osteoporosis. This study is the first to link non-coding SNP with phase separation, providing a new insight into long-range chromatin regulation mechanisms with susceptibility to complex diseases, and finding a potential target for the development of osteoporosis drugs and corresponding translational research.

The association of lipids and novel non-statin lipid-lowering drug target with osteoporosis: evidence from genetic correlations and Mendelian randomization

BACKGROUND

It remains controversial whether lipids affect osteoporosis (OP) or bone mineral density (BMD), and causality has not been established. This study aimed to investigate the genetic associations between lipids, novel non-statin lipid-lowering drug target genes, and OP and BMD.

METHODS

Mendelian randomization (MR) method was used to explore the genetic associations between 179 lipid species and OP, BMD. Drug-target MR analysis was used to explore the causal associations between angiopoietin-like protein 3 (ANGPTL3) and apolipoprotein C3 (APOC3) inhibitors on BMD.

RESULTS

The IVW results with Bonferroni correction indicated that triglyceride (TG) (51:3) (OR = 1.0029; 95% CI: 1.0014-1.0045; P = 0.0002) and TG (56:6) (OR = 1.0021; 95% CI: 1.0008-1.0033; P = 0.0011) were associated with an increased risk of OP; TG (51:2) (OR = 0.9543; 95% CI: 0.9148-0.9954; P = 0.0298) was associated with decreased BMD; and ANGPTL3 inhibitor (OR = 1.1342; 95% CI: 1.0393-1.2290; P = 0.0093) and APOC3 inhibitor (OR = 1.0506; 95% CI: 1.0155-1.0857; P = 0.0058) was associated with increased BMD.

CONCLUSIONS

MR analysis indicated causal associations between genetically predicted TGs and OP and BMD. Drug-target MR analysis showed that ANGPTL3 and APOC3 have the potential to serve as novel non-statin lipid-lowering drug targets to treat or prevent OP.

Integrated transcriptomic analysis of human induced pluripotent stem cell-derived osteogenic differentiation reveals a regulatory role of KLF16

Osteogenic differentiation is essential for bone development, metabolism, and repair; however, the underlying regulatory relationships among genes remain poorly understood. To elucidate the transcriptomic changes and identify novel regulatory genes involved in osteogenic differentiation, we differentiated mesenchymal stem cells (MSCs) derived from 20 human iPSC lines into preosteoblasts (preOBs) and osteoblasts (OBs). We then performed transcriptome profiling of MSCs, preOBs and OBs. The iPSC-derived MSCs and OBs showed similar transcriptome profiles to those of primary human MSCs and OBs, respectively. Differential gene expression analysis revealed global changes in the transcriptomes from MSCs to preOBs, and then to OBs, including the differential expression of 840 genes encoding transcription factors (TFs). TF regulatory network analysis uncovered a network comprising 451 TFs, organized into five interactive modules. Multiscale embedded gene co-expression network analysis (MEGENA) identified gene co-expression modules and key network regulators (KNRs). From these analyses, KLF16 emerged as an important TF in osteogenic differentiation. We demonstrate that overexpression of Klf16 in vitro inhibited osteogenic differentiation and mineralization, while Klf16 +/- mice exhibited increased bone mineral density, trabecular number, and cortical bone area. Our study underscores the complexity of osteogenic differentiation and identifies novel regulatory genes such as KLF16, which plays an inhibitory role in osteogenic differentiation both in vitro and in vivo.

Crispant analysis in zebrafish as a tool for rapid functional screening of disease-causing genes for bone fragility

Heritable fragile bone disorders (FBDs), ranging from multifactorial to rare monogenic conditions, are characterized by an elevated fracture risk. Validating causative genes and understanding their mechanisms remain challenging. We assessed a semi-high throughput zebrafish screening platform for rapid in vivo functional testing of candidate FBD genes. Six genes linked to severe recessive osteogenesis imperfecta (OI) and four associated with bone mineral density (BMD) from genome-wide association studies were analyzed. Using CRISPR/Cas9-based crispant screening in F0 mosaic founder zebrafish, Next-generation sequencing confirmed high indel efficiency (mean 88%), mimicking stable knock-out models. Skeletal phenotyping at 7, 14, and 90 days post-fertilization (dpf) using microscopy, Alizarin Red S staining, and microCT was performed. Larval crispants showed variable osteoblast and mineralization phenotypes, while adult crispants displayed consistent skeletal defects, including malformed neural and haemal arches, vertebral fractures and fusions, and altered bone volume and density. In addition, aldh7a1 and mbtps2 crispants experienced increased mortality due to severe skeletal deformities. RT-qPCR revealed differential expression of osteogenic markers bglap and col1a1a, highlighting their biomarker potential. Our results establish zebrafish crispant screening as a robust tool for FBD gene validation, combining skeletal and molecular analyses across developmental stages to uncover novel insights into gene functions in bone biology.

Systematic functional characterization of non-coding regulatory SNPs associated with central obesity

Central obesity is associated with higher risk of developing a wide range of diseases independent of overall obesity. Genome-wide association studies (GWASs) have identified more than 300 susceptibility loci associated with central obesity. However, the functional understanding of these loci is limited by the fact that most loci are in non-coding regions. To address this issue, our study first prioritized 2,034 single-nucleotide polymorphisms (SNPs) based on fine-mapping and epigenomic annotation analysis. Subsequently, we employed self-transcribing active regulatory region sequencing (STARR-seq) to systematically evaluate the enhancer activity of these prioritized SNPs. The resulting data analysis identified 141 SNPs with allelic enhancer activity. Further analysis of allelic transcription factor (TF) binding prioritized 20 key TFs mediating the central-obesity-relevant genetic regulatory network. Finally, as an example, we illustrate the molecular mechanisms of how rs8079062 acts as an allele-specific enhancer to regulate the expression of its targeted RNF157. We also evaluated the role of RNF157 in the adipogenic differentiation process. In conclusion, our results provide an important resource for understanding the genetic regulatory mechanisms underlying central obesity.

Association between bone mineral density and scoliosis: a two-sample mendelian randomization study in european populations

BACKGROUND

Previous studies have shown that bone mineral density (BMD) has a certain impact on scoliosis. However, up to now, there is no clear evidence that there is a causal association between the two. The aim of this study is to investigate whether there is a causal association between BMD at different body positions and scoliosis by two-sample Mendelian randomization (MR).

METHODS

Genetic variants (SNPS) strongly associated with BMD (total body BMD (TB-BMD), lumbar spine BMD (LS-BMD), femoral neck BMD (FN-BMD), heel BMD (HE-BMD), and forearm BMD (FA-BMD)) were extracted from GEFOS and genome-wide association analysis (GWAS) databases SNPs) were used as instrumental variables (IVs). Scoliosis was also selected from the Finnish database as the outcome. Inverse variance weighting (IVW) method was used as the main analysis method, and multiple sensitivity analysis was performed by combining weighted median, MR-Egger, MR Multi-effect residuals and outliers.

RESULTS

IVW results showed that TB-BMD (OR = 0.83, 95%CI: 0.66-1.55 P = 0.13), LS-BMD (OR = 0.72, 95%CI: 0.52-0.99, P = 0.04), FN-BMD (OR = 0.74, 95%CI: 0.50-1.09, P = 0.13), FA-BMD (OR = 0.95,95%CI: 0.70-1.28, P = 0.75), HE-BMD (OR = 0.91, 95%CI: 0.77-1.08, P = 0.29). Sensitivity analyses showed no evidence of pleiotropy or heterogeneity (p > 0.05) (MR-PRESSO and Cochrane). The results were further validated by leave-one-out test and MR-Egger intercept, which confirmed the robustness of the study results.

CONCLUSION

In conclusion, the present study demonstrates that the causal role of genetic prediction of scoliosis increases with decreasing lumbar BMD. There was no evidence that BMD at the remaining sites has a significant causal effect on scoliosis. Our results suggest that the lumbar spine BMD should be routinely measured in the population at high risk of scoliosis. If osteoporosis occurs, appropriate treatment should be given to reduce the incidence of scoliosis.

CLINICAL TRIAL NUMBER

Not applicable.

Family-based whole-exome sequencing implicates a variant in lysyl oxidase like 4 in atypical femur fractures

Atypical femur fractures (AFFs) are rare adverse events associated with bisphosphonate use, having unclear pathophysiology. AFFs also cluster in families and have occurred in patients with monogenetic bone diseases sometimes without bisphosphonate use, suggesting an underlying genetic susceptibility. Our aim was to identify a genetic cause for AFF in a Caucasian family with 7 members affected by osteoporosis, including 3 siblings with bisphosphonate-associated AFFs. Using whole-exome sequencing, we identified a rare pathogenic variant c.G1063A (p.Gly355Ser) in lysyl oxidase like 4 (LOXL4) among 64 heterozygous rare, protein-altering variants shared by the 3 siblings with AFFs. The same variant was also found in a fourth sibling with a low-trauma femur fracture above the knee, not fulfilling all the ASBMR criteria of AFF and in 1 of 73 unrelated European AFF patients. LOXL4 is involved in collagen cross-linking and may be relevant for microcrack formation and bone repair mechanisms. Preliminary functional analysis showed that skin fibroblast-derived osteoblasts from the unrelated patient with the LOXL4 variant expressed less collagen type I and elastin, while osteogenic differentiation and mineralization were enhanced compared with 2 controls. In conclusion, this LOXL4 variant may underlie AFF susceptibility possibly due to abnormal collagen metabolism, leading to increased formation of microdamage or compromised healing of microcracks in the femur.

SEAD reference panel with 22,134 haplotypes boosts rare variant imputation and genome-wide association analysis in Asian populations

Limited whole genome sequencing (WGS) studies in Asian populations result in a lack of representative reference panels, thus hindering the discovery of ancestry-specific variants. Here, we present the South and East Asian reference Database (SEAD) panel ( https://imputationserver.westlake.edu.cn/ ), which integrates WGS data for 11,067 individuals from various sources across 17 Asian countries. The SEAD panel, comprising 22,134 haplotypes and 88,294,957 variants, demonstrates improved imputation accuracy for South Asian populations compared to 1000 Genomes Project, TOPMed, and ChinaMAP panels, with a higher proportion of well-imputed rare variants. For East Asian populations, SEAD shows concordance comparable to ChinaMAP, but outperforming TOPMed. Additionally, we apply the SEAD panel to conduct a genome-wide association study for total hip (Hip) and femoral neck (FN) bone mineral density (BMD) traits in 5369 genotyped Chinese samples. The single-variant test suggests that rare variants near SNTG1 are associated with Hip BMD (rs60103302, MAF = 0.0092, P = 1.67 × 10-7), and variant-set analysis further supports the association (Pslide_window = 9.08 × 10-9, Pgene_centric = 5.27 × 10-8). This association was not reported previously and can only be detected by using Asian reference panels. Preliminary in vitro experiments for one of the rare variants identified provide evidence that it upregulates SNTG1 expression, which could in turn inhibit the proliferation and differentiation of preosteoblasts.

GWAS-Informed data integration and non-coding CRISPRi screen illuminate genetic etiology of bone mineral density

Over 1,100 independent signals have been identified with genome-wide association studies (GWAS) for bone mineral density (BMD), a key risk factor for mortality-increasing fragility fractures; however, the effector gene(s) for most remain unknown. Informed by a variant-to-gene mapping strategy implicating 89 non-coding elements predicted to regulate osteoblast gene expression at BMD GWAS loci, we executed a single-cell CRISPRi screen in human fetal osteoblasts (hFOBs). The BMD relevance of hFOBs was supported by heritability enrichment from stratified LD-score regression involving 98 cell types grouped into 15 tissues. 23 genes showed perturbation in the screen, with four (ARID5B, CC2D1B, EIF4G2, and NCOA3) exhibiting consistent effects upon siRNA knockdown on three measures of osteoblast maturation and mineralization. Lastly, additional heritability enrichments, genetic correlations, and multi-trait fine-mapping revealed unexpectedly that many BMD GWAS signals are pleiotropic and likely mediate their effects via non-bone tissues. Extending our CRISPRi screening approach to these tissues could play a key role in fully elucidating the etiology of BMD.

Enhanced osteogenic potential of iPSC-derived mesenchymal progenitor cells following genome editing of GWAS variants in the RUNX1 gene

Recent genome-wide association studies (GWAS) identified 518 significant loci associated with bone mineral density (BMD), including variants at the RUNX1 locus (rs13046645, rs2834676, and rs2834694). However, their regulatory impact on RUNX1 expression and bone formation remained unclear. This study utilized human induced pluripotent stem cells (iPSCs) differentiated into osteoblasts to investigate these variants' regulatory roles. CRISPR/Cas9 was employed to generate mutant (Δ) iPSC lines lacking these loci at the RUNX1 locus. Deletion lines (Δ1 and Δ2) were created in iPSCs to assess the effects of removing regions containing these loci. Deletion lines exhibited enhanced osteogenic potential, with increased expression of osteogenic marker genes and Alizarin Red staining. Circularized chromosome conformation capture (4C-Seq) was utilized to analyze interactions between BMD-associated loci and the RUNX1 promoter during osteogenesis. Analysis revealed altered chromatin interactions with multiple gene promoters including RUNX1 isoform, as well as SETD4, a histone methyltransferase, indicating their regulatory influence. Interestingly, both deletion lines notably stimulated the expression of the long isoform of RUNX1, with more modest effects on the shorter isoform. Consistent upregulation of SETD4 and other predicted targets within the Δ2 deletion suggested its removal removed a regulatory hub constraining expression of multiple genes at this locus. In vivo experiments using a bone defect model in mice demonstrated increased bone regeneration with homozygous deletion of the Δ2 region. These findings indicate that BMD-associated variants within the RUNX1 locus regulate multiple effector genes involved in osteoblast commitment, providing valuable insights into genetic regulation of bone density and potential therapeutic targets.

Chromatin accessibility: biological functions, molecular mechanisms and therapeutic application

The dynamic regulation of chromatin accessibility is one of the prominent characteristics of eukaryotic genome. The inaccessible regions are mainly located in heterochromatin, which is multilevel compressed and access restricted. The remaining accessible loci are generally located in the euchromatin, which have less nucleosome occupancy and higher regulatory activity. The opening of chromatin is the most important prerequisite for DNA transcription, replication, and damage repair, which is regulated by genetic, epigenetic, environmental, and other factors, playing a vital role in multiple biological progresses. Currently, based on the susceptibility difference of occupied or free DNA to enzymatic cleavage, solubility, methylation, and transposition, there are many methods to detect chromatin accessibility both in bulk and single-cell level. Through combining with high-throughput sequencing, the genome-wide chromatin accessibility landscape of many tissues and cells types also have been constructed. The chromatin accessibility feature is distinct in different tissues and biological states. Research on the regulation network of chromatin accessibility is crucial for uncovering the secret of various biological processes. In this review, we comprehensively introduced the major functions and mechanisms of chromatin accessibility variation in different physiological and pathological processes, meanwhile, the targeted therapies based on chromatin dynamics regulation are also summarized.

Forkhead box C1 promotes the pathology of osteoarthritis in subchondral bone osteoblasts via the Piezo1/YAP axis

Subchondral bone sclerosis is a key characteristic of osteoarthritis (OA). Prior research has shown that Forkhead box C1 (FoxC1) plays a role in the synovial inflammation of OA, but its specific role in the subchondral bone of OA has not been explored. Our research revealed elevated expression levels of FoxC1 and Piezo1 in OA subchondral bone tissues. Further experiments on OA subchondral bone osteoblasts with FoxC1 or Piezo1 overexpression showed increased cell proliferation activity, expression of Yes-associated Protein 1 (YAP) and osteogenic markers, and secretion of proinflammatory factors. Mechanistically, the overexpression of FoxC1 through Piezo1 activation, in combination with downstream YAP signaling, led to increased levels of alkaline phosphatase (ALP), collagen type 1 (COL1) A1, RUNX2, Osteocalcin, matrix metalloproteinase (MMP) 3, and MMP9 expression. Notably, inhibition of Piezo1 reversed the regulatory function of FoxC1. The binding of FoxC1 to the targeted area (ATATTTATTTA, residues +612 to +622) and the activation of Piezo1 transcription were verified by the dual luciferase assays. Additionally, Reduced subchondral osteosclerosis and microangiogenesis were observed in knee joints from FoxC1-conditional knockout (CKO) and Piezo1-CKO mice, indicating reduced lesions. Collectively, our study reveals the significant involvement of FoxC1 in the pathologic process of OA subchondral bone via the Piezo1/YAP signaling pathway, potentially establishing a novel therapeutic target.

TransferGWAS of T1-weighted brain MRI data from UK Biobank

Genome-wide association studies (GWAS) traditionally analyze single traits, e.g., disease diagnoses or biomarkers. Nowadays, large-scale cohorts such as UK Biobank (UKB) collect imaging data with sample sizes large enough to perform genetic association testing. Typical approaches to GWAS on high-dimensional modalities extract predefined features from the data, e.g., volumes of regions of interest. This limits the scope of such studies to predefined traits and can ignore novel patterns present in the data. TransferGWAS employs deep neural networks (DNNs) to extract low-dimensional representations of imaging data for GWAS, eliminating the need for predefined biomarkers. Here, we apply transferGWAS on brain MRI data from UKB. We encoded 36, 311 T1-weighted brain magnetic resonance imaging (MRI) scans using DNN models trained on MRI scans from the Alzheimer's Disease Neuroimaging Initiative, and on natural images from the ImageNet dataset, and performed a multivariate GWAS on the resulting features. We identified 289 independent loci, associated among others with bone density, brain, or cardiovascular traits, and 11 regions having no previously reported associations. We fitted polygenic scores (PGS) of the deep features, which improved predictions of bone mineral density and several other traits in a multi-PGS setting, and computed genetic correlations with selected phenotypes, which pointed to novel links between diffusion MRI traits and type 2 diabetes. Overall, our findings provided evidence that features learned with DNN models can uncover additional heritable variability in the human brain beyond the predefined measures, and link them to a range of non-brain phenotypes.

The DLEU2-miR-15a-16-1 Cluster Is a Determinant of Bone Microarchitecture and Strength in Postmenopausal Women and Mice

This study explores how select microRNAs (miRNAs) influence bone structure in humans and in transgenic mice. In trabecular bone biopsies from 84 postmenopausal women (healthy, osteopenic, and osteoporotic), we demonstrate that DLEU2 (deleted in lymphocytic leukemia 2)-encoded miR-15a-5p is strongly positively associated with bone mineral density (BMD) at different skeletal sites. In bone transcriptome analyses, miR-15a-5p levels correlated positively with the osteocyte characteristic transcripts SOST (encoding sclerostin) and MEPE (Matrix Extracellular Phosphoglycoprotein), while the related miR-15b-5p showed a negative association with BMD and osteoblast markers. The data imply that these miRNAs have opposite roles in bone remodeling with distinct actions on bone cells. Expression quantitative trait loci (eQTL) variants confirmed earlier DLEU2 associations. Furthermore, a novel variant (rs12585295) showed high localization with transcriptionally active chromatin states in osteoblast primary cell cultures. The supposition that DLEU2-encoded miRNAs have an important regulatory role in bone remodeling was further confirmed in a transgenic mice model showing that miR-15a/16-1-deleted mice had significantly higher percentage bone volume and trabecular number than the wild type, possibly due to prenatal actions. However, the three-point mechanical break force test of mice femurs showed a positive correlation between strength and miR-15a-5p/miR-16-5p levels, indicating differential effects on cortical and trabecular bone. Moreover, these miRNAs appear to have distinct and complex actions in mice prenatally and in adult humans, impacting BMD and microstructure by regulating bone cell transcription. However, detailed interactions between these miRNAs and their downstream mechanisms in health and disease need further clarification.

The Genetic Variants Influencing Hypertension Prevalence Based on the Risk of Insulin Resistance as Assessed Using the Metabolic Score for Insulin Resistance (METS-IR)

Insulin resistance is a major indicator of cardiovascular diseases, including hypertension. The Metabolic Score for Insulin Resistance (METS-IR) offers a simplified and cost-effective way to evaluate insulin resistance. This study aimed to identify genetic variants associated with the prevalence of hypertension stratified by METS-IR score levels. Data from the Korean Genome and Epidemiology Study (KoGES) were analyzed. The METS-IR was calculated using the following formula: ln [(2 × fasting blood glucose (FBG) + triglycerides (TG)) × body mass index (BMI)]/ ln [high-density lipoprotein cholesterol (HDL-C)]. The participants were divided into tertiles 1 (T1) and 3 (T3) based on their METS-IR scores. Genome-wide association studies (GWAS) were performed for hypertensive cases and non-hypertensive controls within these tertile groups using logistic regression adjusted for age, sex, and lifestyle factors. Among the METS-IR tertile groups, 3517 of the 19,774 participants (17.8%) at T1 had hypertension, whereas 8653 of the 20,374 participants (42.5%) at T3 had hypertension. A total of 113 single-nucleotide polymorphisms (SNPs) reached the GWAS significance threshold (p < 5 × 10-8) in at least one tertile group, mapping to six distinct genetic loci. Notably, four loci, rs11899121 (chr2p24), rs7556898 (chr2q24.3), rs17249754 (ATP2B1), and rs1980854 (chr20p12.2), were significantly associated with hypertension in the high-METS-score group (T3). rs10857147 (FGF5) was significant in both the T1 and T3 groups, whereas rs671 (ALDH2) was significant only in the T1 group. The GWASs identified six genetic loci significantly associated with hypertension, with distinct patterns across METS-IR tertiles, highlighting the role of metabolic context in genetic susceptibility. These findings underscore critical genetic factors influencing hypertension prevalence and provide insights into the metabolic-genetic interplay underlying this condition.

EPSTI1 promotes osteoclast differentiation and bone resorption by PKR/NF-κB signaling

BACKGROUND

Epithelial stromal interaction 1 (EPSTI1) plays an important role in M1 macrophages, which induce osteoclastogenesis. One recent genome-wide association study (GWAS) involving 426,824 individuals has shown that EPSTI1 is strongly associated with osteoporosis (P < 5E-8). Therefore, we speculate that EPSTI1 participates in the modulation of osteoporosis through osteoclastogenesis. The roles of EPSTI1 in osteoclastogenesis and bone resorption remain unclear.

METHODS

Femur specimens were collected from osteoporotic patients and control patients. Immunofluorescence staining was used to detect the expression of EPSTI1 and signaling pathways. The osteoclastic potential of RAW264.7 cells with Sh-EPSTI1 lentivirus infection was tested using tartrate-resistant acid phosphatase (TRAP) staining, western blotting, and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Western blotting was also used to examine signaling pathways.

RESULTS

In this study, EPSTI1 was found to be significantly increased in tartrate-resistant acid phosphatase positive (ACP5+) osteoclasts of bone sections from osteoporotic patients. Next, we identified EPSTI1 as a positive regulator of osteoclastogenesis and osteoclast differentiation capability. Diminished EPSTI1 expression resulted in reduced osteoclastic resorption. Mechanistically, EPSTI1-driven osteoclastogenesis was regulated by NF-κB pathway, which was mediated by the phosphorylation of protein kinase R (p-PKR). Furthermore, EPSTI1 participating in the modulation of osteoporosis via PKR/NF-κB pathway was also verified in the bone samples of osteoporotic patients.

CONCLUSIONS

Collectively, our findings suggest that EPSTI1 may regulate osteoclast differentiation and bone resorption through PKR/NF-κB pathway and in vivo experiments are needed to further verify EPSTI1 as the therapy target for osteoporosis.

A novel small molecule screening assay using normal human chondrocytes toward osteoarthritis drug discovery

Osteoarthritis (OA) is the most common form of arthritis and a leading cause of pain and disability in adults. A central feature is progressive cartilage degradation and matrix fragment formation driven by the excessive production of matrix metalloproteinases (MMPs), such as MMP-13, by articular chondrocytes. Inflammatory factors, including interleukin 6 (IL-6), are secreted into the joint by synovial fibroblasts, and can contribute to pain and inflammation. No therapeutic exists that addresses the underlying loss of joint tissue in OA. To address this, we developed and utilized a cell-based high-throughput OA drug discovery platform using normal human chondrocytes treated with a recombinant fragment of the matrix protein fibronectin (FN-f) as a catabolic stimulus relevant to OA pathogenesis and a readout using a fluorescent MMP-13 responsive probe. The goal was to test this screening platform by identifying compounds that inhibited FN-f-induced MMP-13 production and determine if these compounds also inhibited catabolic signaling in OA chondrocytes and synovial fibroblasts. Two pilot screens of 1344 small molecules revealed five "hits" that strongly inhibited FN-f induced MMP-13 production with low cytotoxicity. These included RO-3306 (CDK1 inhibitor (i)), staurosporine (PKCi), trametinib (MEK1 and MEK2i), GSK-626616 (DYRK3i), and edicotinib (CSF-1Ri). Secondary testing using immunoblots and cells derived from OA joint tissues confirmed the ability of selected compounds to inhibit chondrocyte MMP-13 production and FN-f stimulated IL-6 production by synovial fibroblasts. These findings support the use of this high throughput screening assay for discovery of disease-modifying osteoarthritis drugs.