Identification of new therapeutic targets for osteoarthritis through genome-wide analyses of UK Biobank data

Unveiling the ageing-related genes in diagnosing osteoarthritis with metabolic syndrome by integrated bioinformatics analysis and machine learning

Ageing significantly contributes to osteoarthritis (OA) and metabolic syndrome (MetS) pathogenesis, yet the underlying mechanisms remain unknown. This study aimed to identify ageing-related biomarkers in OA patients with MetS. OA and MetS datasets and ageing-related genes (ARGs) were retrieved from public databases. The limma package was used to identify differentially expressed genes (DEGs), and weighted gene coexpression network analysis (WGCNA) screened gene modules, and machine learning algorithms, such as random forest (RF), support vector machine (SVM), generalised linear model (GLM), and extreme gradient boosting (XGB), were employed. The nomogram and receiver operating characteristic (ROC) curve assess the diagnostic value, and CIBERSORT analysed immune cell infiltration. We identified 20 intersecting genes among DEGs of OA, key module genes of MetS, and ARGs. By comparing the accuracy of the four machine learning models for disease prediction, the SVM model, which includes CEBPB, PTEN, ARPC1B, PIK3R1, and CDC42, was selected. These hub ARGs not only demonstrated strong diagnostic values based on nomogram data but also exhibited a significant correlation with immune cell infiltration. Building on these findings, we have identified five hub ARGs that are associated with immune cell infiltration and have constructed a nomogram aimed at early diagnosing OA patients with MetS.

Bionic ECM scaffolds for directional articular hyaline cartilage regeneration and long-term homeostasis maintenance

Cartilage defects play a key role in osteoarthritis, causing functional impairment as the disease progresses. Microfracture surgery is commonly used to treat articular cartilage defects, providing early pain relief and functional improvement. However, the blood clot formed during the procedure differs from the natural cartilage microenvironment, hindering hyaline cartilage formation and promoting fibrocartilage, which limits long-term outcomes. This study proposes combining a bionic flexible extracellular matrix (ECM) scaffold with microfracture surgery as a treatment for cartilage defects. By filling the microfracture site with the scaffold and thermosensitive agarose gel, we can anchor BMSCs leaking from the bone marrow while creating a 3D microenvironment that regulates stem cell differentiation. Our results show that the scaffold's mechanical strength is comparable to that of hyaline cartilage, offering excellent biomimetic properties and biocompatibility. In vitro, BMSCs migrating into the scaffold exhibited a survival rate of nearly 90 % by day 2, significantly higher than the 25 % survival rate in the control agarose gel group, with cells observed anchoring around the scaffold. In vivo, stem cells anchored to the scaffold successfully differentiated into articular hyaline cartilage, driven by the combined effects of the scaffold's physical structure and its contained cytokines. The generated hyaline cartilage maintains homeostasis over time, reducing the risk of fibrocartilage formation. This strategy addresses a key limitation of microfracture surgery, where regenerated cartilage is often fibrocartilage, offering a promising new approach for cartilage repair.

Osteosarcopenia, osteoarthritis and frailty: a two-sample Mendelian randomization study

BACKGROUND

Musculoskeletal disease, which has a complicated relationship with frailty, is a common clinical problem among elderly individuals.

AIMS

This study evaluated the potential causal relationships between osteosarcopenia, osteoarthritis and frailty by Mendelian Randomization (MR) analysis.

METHODS

This study employed a two-sample MR approach to investigate the causal relationships among osteosarcopenia, osteoarthritis and frailty. Published summary statistics were used to obtain instrumental variables at the genome-wide significance level.

RESULTS

Among the age groups with osteoporosis, high total bone mineral density (TBMD) (45-60, OR = 0.966, 95% CI 0.940-0.993, P = 0.013) and TBMD (over 60, OR = 0.974, 95% CI 0.954-0.994, P = 0.011) reduced the risk of frailty. Similarly, high forearm BMD (FA-BMD), high ultradistal forearm BMD (UFA-BMD), and high Heel-BMD at different sites also reduced the risk of frailty (OR = 0.966, 95% CI 0.936-0.996, P = 0.028; OR = 0.975, 95% CI 0.953-0.997, P = 0.029; OR = 0.981, 95% CI 0.967-0.995, P = 0.008). Among the characteristics related to sarcopenia, grip strength in the left hand, grip strength in the right hand, appendicular lean mass, and walking pace were all protective factors for frailty (OR = 0.788, 95% CI 0.721-0.862, P < 0.001; OR = 0.800, 95% CI 0.737-0.869, P < 0.001; OR = 0.955, 95% CI 0.937-0.974, P = 0.000; OR = 0.480, 95% CI 0.388-0.593, P < 0.001), with low grip strength in those over 60 years of age significantly positively correlated with frailty (OR = 1.168, 95% CI 1.059-1.289, P = 0.002). The MR results of osteoarthritis and frailty revealed a causal relationship between specific joint sites and frailty, including KOA (OR = 1.086, 95% CI 1.017-1.160, P = 0.014), HOA (OR = 1.028, 95% CI 1.007-1.049, P = 0.009), and KOA/HOA (OR = 1.082, 95% CI 1.053-1.113, P = 0.000), increasing the risk of frailty.

CONCLUSION

Osteosarcopenia, osteoarthritis and frailty exhibit significant causal effects, rendering them risk factors for frailty. Therefore, in clinical practice, patients with osteosarcopenia and osteoarthritis should be required to undergo relevant interventions to reduce the risk of frailty.

Decomposing the genetic background of chronic back pain

Chronic back pain (CBP) is a disabling condition with a lifetime prevalence of 40% and a substantial socioeconomic burden. Because of the high heterogeneity of CBP, subphenotyping may help to improve prediction and support personalized treatment of CBP. To investigate CBP subphenotypes, we decomposed its genetic background into a shared one common to other chronic pain conditions (back, neck, hip, knee, stomach, and head pain) and unshared genetic background specific to CBP. We identified and replicated 18 genes with shared impact across different chronic pain conditions and two genes that were specific for CBP. Among people with CBP, we demonstrated that polygenic risk scores accounting for the shared and unshared genetic backgrounds of CBP may underpin different CBP subphenotypes. These subphenotypes are characterized by varying genetic predisposition to diverse medical conditions and interventions such as diabetes mellitus, myocardial infarction, diagnostic endoscopic procedures, and surgery involving muscles, bones, and joints.

Genetic evidence links hyperthyroidism to knee osteoarthritis

PURPOSE

The causal relationship between hyperthyroidism and knee osteoarthritis (KOA) remains to date unknown. We aimed to examine the potential causal relationship between hyperthyroidism status and the risk of developing KOA via a bidirectional two-sample Mendelian randomization (MR) approach.

METHODS

Single-nucleotide polymorphism (SNP) data related to hyperthyroidism and KOA were obtained from a genome-wide association study (GWAS) in Europe. KOA was used as the outcome variable and hyperthyroidism was used as the exposure factor. The inverse-variance weighted (IVW) method served as the primary analytic tool and heterogeneity and pleiotropy were evaluated via sensitivity analysis.

RESULTS

The IVW method indicated that hyperthyroidism status has a causative influence on the risk of developing KOA [OR, 1.046; 95% confidence interval (CI), 1.013-1.080; P = 0.006]. No significant reverse causality was detected. Sensitivity analyses validated the robustness of these findings.

CONCLUSIONS

Hyperthyroidism status can causally increase the risk of developing KOA. This result indicated that the risk of developing KOA may be decreased by controlling hyperthyroidism.

Unraveling the brain-joint axis: genetic, transcriptomic, and cohort insights from neuroticism to osteoarthritis

The causal relationships between neuroticism and osteoarthritis (OA) were inconclusive in observational studies. We conducted bidirectional two-sample Mendelian randomization (MR) and transcriptome-wide association studies to determine the associations and the underlying transcriptomic basis. The summary-level genome-wide association study data for any site OA, knee OA, erosive hand OA, and hip OA were mainly derived from UK Biobank, and neuroticism was derived from CTGlab. We then utilized weighted regression and propensity score matching (PSM) models to investigate the relationship between neuroticism and OA in 11,948 participants of European ancestry from the National Health and Nutrition Examination Survey from 2005 to 2018. Bidirectional two-sample MR studies revealed that feelings of being fed-up, a sense of miserableness, mood swings, and a higher neuroticism score were all linked to an increased risk of OA. These factors were specifically associated with OA at various sites, including the knee. Conversely, there was no evidence to suggest that OA had any influence on traits related to neuroticism. In a comprehensive analysis that accounted for variables such as age, sex, blood lipids, blood glucose, body weight, smoking, alcohol consumption, and physical activity, it was determined that mental fluctuation significantly increased the incidence of self-reported OA (OR 1.37, 95% CI 1.20-1.58, P < 0.001) based on weighted regression. Further confirmation was provided by PSM analysis, which showed that mental fluctuation was associated with a higher incidence of self-reported OA (OR 1.28, 95% CI 1.08-1.52, P = 0.004). Moreover, differentially expressed genes were enriched in several biological processes, including the cell cycle, lipid metabolism, RNA processing, and immuno-inflammatory responses. The results revealed significant genetic and population-based associations, as well as underlying mechanisms, between neuroticism and osteoarthritis, supporting the concept of a brain-joint axis.

Lessons from national biobank projects utilizing whole-genome sequencing for population-scale genomics

Large-scale national biobank projects utilizing whole-genome sequencing have emerged as transformative resources for understanding human genetic variation and its relationship to health and disease. These initiatives, which include the UK Biobank, All of Us Research Program, Singapore's PRECISE, Biobank Japan, and the National Project of Bio-Big Data of Korea, are generating unprecedented volumes of high-resolution genomic data integrated with comprehensive phenotypic, environmental, and clinical information. This review examines the methodologies, contributions, and challenges of major WGS-based national genome projects worldwide. We first discuss the landscape of national biobank initiatives, highlighting their distinct approaches to data collection, participant recruitment, and phenotype characterization. We then introduce recent technological advances that enable efficient processing and analysis of large-scale WGS data, including improvements in variant calling algorithms, innovative methods for creating multi-sample VCFs, optimized data storage formats, and cloud-based computing solutions. The review synthesizes key discoveries from these projects, particularly in identifying expression quantitative trait loci and rare variants associated with complex diseases. Our review introduces the latest findings from the National Project of Bio-Big Data of Korea, which has advanced our understanding of population-specific genetic variation and rare diseases in Korean and East Asian populations. Finally, we discuss future directions and challenges in maximizing the impact of these resources on precision medicine and global health equity. This comprehensive examination demonstrates how large-scale national genome projects are revolutionizing genetic research and healthcare delivery while highlighting the importance of continued investment in diverse, population-specific genomic resources.

Transforming growth factor beta induces interleukin-11 expression in osteoarthritis

Interleukin-11 (IL-11) is a member of the IL-6 family of cytokines and possesses both pro- and anti-inflammatory properties. IL-11 activates its target cells via binding to a membrane-bound IL-11R and subsequent formation of a homodimer of the signal-transducing receptor gp130. Thus, the expression pattern of the IL-11R determines which cells can be activated by IL-11. However, knowledge about IL-11 target cells and cells that secrete IL-11 are sparse, and the overall roles of IL-11 in inflammatory diseases are largely unexplored. In this study, we show that high amounts of IL-11 can be detected via ELISA in the synovial fluid of osteoarthritis (OA) patients in comparison to rheumatoid arthritis (RA) patients. Using primary cells and tissue of OA patients, we show that IL-11 is expressed by chondrocytes in cartilage, but not in the synovium. We further identify the cytokine transforming growth factor β 1(TGF-β1) as a potent inducer of IL-11 secretion in both primary chondrocytes and fibroblasts, and TGF-β1 and IL-11 levels correlate significantly in the synovial fluid of OA patients. Using immunohistochemistry, we show that both cartilage and synovium express IL-11R, and the amount of IL-11R is independent of the disease severity. Primary chondrocytes and fibroblasts from OA patients respond to IL-11 stimulation with potent activation of the Jak/STAT3 signaling cascade, suggesting that these cell types are not only the source, but also the targets of IL-11 in OA patients. Our results uncover IL-11 as a potential new target for therapy in OA.

Genetic Estimates of Correlation and Causality Between Keratoconus and Osteoarthritis

PURPOSE

The relationship between keratoconus (KC) and osteoarthritis (OA) has been hypothesized, yet the causal link remained obscure. We aimed to evaluate the genetic correlation and causality between KC and OA through a genetic perspective.

METHODS

Linkage Disequilibrium Score Regression and bidirectional 2-sample Mendelian randomization (MR) analysis were conducted. Data were used from genome-wide association study on KC (4669 cases and 116,547 controls), OA (encompassing 24,955 patients with knee OA, 15,704 patients with hip OA, 39,427 patients with knee or hip OA, and 378,169 control participants), and KC data in the FinnGen consortium for replication and meta-analysis. Simple model, weighted model, inverse-variance weighted, weighted median, and MR-Egger regression were employed to assess the causal effects. MR pleiotropy residual sum and outlier method, MR-Egger method, and leave-one-out analysis were also applied to detect pleiotropy.

RESULTS

No statistically significant genetic correlation between KC and OA (all P > 0.05) were observed. MR estimates obtained from all 5 methods after meta-analysis revealed nonsignificant odds ratio values of KC-related traits to knee OA, hip OA, and OA (all adjusted P > 0.05). No evidence of causal relationships of knee and hip OA with KC-related traits was detected after meta-analysis of all 5 MR methods (all adjusted P > 0.05).

CONCLUSIONS

The large MR analysis indicated that KC may not be causally associated with a risk of OA.

iPSCs and iPSC-derived cells as a model of human genetic and epigenetic variation

Understanding the interaction between genetic and epigenetic variation remains a challenge due to confounding environmental factors. We propose that human induced Pluripotent Stem Cells (iPSCs) are an excellent model to study the relationship between genetic and epigenetic variation while controlling for environmental factors. In this study, we have created a comprehensive resource of high-quality genomic, epigenomic, and transcriptomic data from iPSC lines and three iPSC-derived cell types (neural stem cell (NSC), motor neuron, monocyte) from three healthy donors. We find that epigenetic variation is most strongly associated with genetic variation at the iPSC stage, and that relationship weakens as epigenetic variation increases in differentiated cells. Additionally, cell type is a stronger source of epigenetic variation than genetic variation. Further, we elucidate a utility of studying epigenetic variation in iPSCs and their derivatives for identifying important loci for GWAS studies and the cell types in which they may be acting.

Treatment with a superoxide dismutase mimetic for joint preservation during 35 and 75 days in orbit aboard the international space station, and after 120 days recovery on Earth

Reduced weight-bearing during spaceflight has been associated with musculoskeletal degradation that risks astronaut health and performance in transit and upon reaching deep space destinations. Previous rodent experiments aboard the international space station (ISS) have identified that the spaceflight-induced molecular arthritic phenotype was characterized with an increase in oxidative stress. This study evaluated if treatment with a superoxide dismutase (SOD) mimetic on orbit could prevent spaceflight-induced damage to the knee and hip articular cartilage, and the menisci in rodents. Cartilage and meniscal degradation in mice were measured via microCT, histology, and transcriptomics after: (1) ∼ 35 days on the ISS, (2) ∼ 35 days on the ISS followed by 120 days weight-bearing readaptation on Earth or (3) ∼ 75 days on the ISS. The study had a limited sample size, so both significant effects and generalized patterns are reported. After 35 days aboard the ISS, cartilage volume at the tibial-femoral cartilage-cartilage contact point decreased, meniscal volume decreased concurrent with an increase in pro-osteoarthritic signaling in the joint soft tissue. Similarly, a decrease in cortical and trabecular bone volume of the tibia was observed. Treatment with the SOD mimetic preserved the trabecular bone, articular cartilage and the menisci after 35 days aboard the ISS, but had limited efficacy retaining that recovery after 120 days of weight bearing, and after 75 days on orbit. Antioxidants including BuOE may serve as a potential countermeasure option to protect musculoskeletal health during spaceflight missions, and continued use may be necessary upon reaching a destination.

From metabolomics to therapeutics: identifying causal metabolites and potential drugs for the treatment of osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a common age-related disease that causes pain and impaired mobility. Various blood metabolites are reportedly associated with bone health; however, their impact on OA remains unclear. Therefore, we conducted a metabolome-wide Mendelian randomization (MR) study to identify causal metabolites and therapeutic targets in OA.

METHODS

Genetic associations of metabolites were derived from the largest genome-wide association study (GWAS) of the blood metabolome, which provided summary-level data on 1091 blood metabolites. Genetic associations with OA were obtained from four large-scale GWAS: McDonald's study (140,025 cases, 344,349 controls), Zengini's study (12,658 cases, 50,898 controls), Dönertaş's study (39,515 cases, 445,083 controls), and Tachmazidou's study (39,427 cases, 378,169 controls). MR and colocalization analyses were performed to validate the causal roles of the candidate metabolites. Further analyses were conducted using expression quantitative trait locus-based MR, single-cell sequencing data, protein-protein interaction networks, and druggability assessments. These analyses aimed to identify the differentially expressed genes and prioritize them as potential therapeutic targets.

RESULTS

The genetically predicted levels of 10 metabolites were associated with OA. Elevated levels of five metabolites and reduced levels of another five metabolites were associated with an increased OA risk. Among these, five metabolites were prioritized based on the most compelling evidence. Seven genes were identified as potentially involved and could serve as novel therapeutic targets for OA.

CONCLUSION

Several blood metabolites were associated with OA, providing new insights into the etiology of OA and highlighting promising therapeutic targets.

Advances in the pathology and treatment of osteoarthritis

BACKGROUND

Osteoarthritis (OA), a widespread degenerative joint disease, predominantly affects individuals from middle age onwards, exhibiting non-inflammatory characteristics. OA leads to the gradual deterioration of articular cartilage and subchondral bone, causing pain and reduced mobility. The risk of OA increases with age, making it a critical health concern for seniors. Despite significant research efforts and various therapeutic approaches, the precise causes of OA remain unclear.

AIM OF REVIEW

This paper provides a thorough examination of OA characteristics, pathogenic mechanisms at various levels, and personalized treatment strategies for different OA stages. The review aims to enhance understanding of disease mechanisms and establish a theoretical framework for developing more effective therapeutic interventions.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review systematically examines OA through multiple perspectives, integrating current knowledge of clinical presentation, pathological mechanisms, and associated signaling pathways. It assesses diagnostic methods and reviews both pharmacological and surgical treatments for OA, as well as emerging tissue engineering approaches to manage the disease. While therapeutic strategies such as exercise, anti-inflammatory drugs, and surgical interventions are employed to manage symptoms and modify joint structure, none have been able to effectively halt OA's advancement or achieve long-lasting symptom relief. Tissue engineering strategies, such as cell-seeded scaffolds, supportive matrices, and growth factor delivery, have emerged as promising approaches for cartilage repair and OA treatment. To combat the debilitating effects of OA, it is crucial to investigate the molecular basis of its pathogenesis and seek out innovative therapeutic targets for more potent preventive and treatment strategies.

Exploring the therapeutic effect of human recombinant IL11 on lesioned OA human osteochondral explants

OBJECTIVE

To explore IL11 co-expression profiles in our previously reported RNA-sequencing dataset of OA articular cartilage, in interaction with IL6, and to investigate the effects of hrIL11 administration as potential therapeutic strategy for OA articular cartilage using our biomimetic aged human osteochondral explant model of OA.

METHODS

We used RNA-sequencing datasets of macroscopically preserved and lesioned OA articular cartilage (N = 35 patients). Spearman correlations were calculated between IL11 and IL6 expression levels and genes expressed in cartilage (N = 20048 genes). Osteochondral explants were isolated from macroscopically preserved and lesioned areas of the joint and were kept in culture for two weeks, with or without exposure to 200ng/ml hrIL11.

RESULTS

We found no overlap in correlating genes between IL11 and IL6, indicating their distinct roles in articular cartilage. Moreover, we identified more genes being correlated to IL11 in the lesioned compared to preserved articular cartilage (N = 203 and 106 genes, respectively). Upon treatment of ex vivo OA articular cartilage with hrIL11, we overall observed unbeneficial effects on chondrocyte phenotype, as illustrated by upregulation of MMP13, EPAS1, RUNX2, and POSTN. We did not observe significant differences in Mankin scores upon addition of hrIL11.

CONCLUSION

The current study showed that treatment of OA articular cartilage with hrIL11 is unlikely to be beneficial despite previous indications of hrIL11 as potential druggable target. These findings underscore the importance of functionally investigating OA risk genes. Better understanding of IL11 signaling and the underlying pathways is necessary towards the development of OA treatment strategy.

A genome-wide association study identifies genetic variants associated with hip pain in the UK Biobank cohort (N = 221,127)

Hip pain is a common musculoskeletal complaint that leads many people to seek medical attention. We conducted a primary genome-wide association study (GWAS) on the hip pain phenotype within the UK Biobank cohort. Sex-stratified GWAS analysis approach was also performed to explore sex specific variants associated with hip pain. We found seven different loci associated with hip pain at GWAS significance level, with the most significant single nucleotide polymorphism (SNP) being rs77641763 within the EXD3 (p value = 2.20 × 10-13). We utilized summary statistics from the FinnGen cohort and a previous GWAS meta-analysis on hip osteoarthritis as replication cohorts. Four loci (rs509345, rs73581564, rs9597759, rs2018384) were replicated with a p value less than 0.05. Sex-stratified GWAS analyses revealed a unique locus within the CUL1 gene (rs4726995, p = 2.56 × 10-9) in males, and three unique loci in females: rs1651359966 on chromosome 7 (p = 1.15 × 10-8), rs552965738 on chromosome 9 (p = 2.72 × 10-8), and rs1978969 on chromosome 13 (p = 2.87 × 10-9). This study has identified seven genetic loci associated with hip pain. Sex-stratified analysis also revealed sex specific variants associated with hip pain in males and females. This study has provided a foundation for advancing research of hip pain and hip osteoarthritis.

Genetic Links Between Metabolic Syndrome and Osteoarthritis: Insights From Cross-Trait Analysis

CONTEXT

Previous observational studies have indicated a bidirectional association between metabolic syndrome (MetS) and osteoarthritis (OA). However, it remains unclear whether these bidirectional associations reflect causal relationships or shared genetic factors, and the underlying biological mechanisms of this association are not fully understood.

OBJECTIVE

We aimed to explore the genetic connection between MetS and OA using genome-wide association study (GWAS) summary data.

METHODS

Leveraging summary statistics from GWAS conducted by the UK Biobank and the Glucose and Insulin-related Traits Consortium (MAGIC), we performed global genetic correlation analyses, genome-wide cross-trait meta-analyses, and a bidirectional two-sample Mendelian randomization analyses using summary statistics from GWAS to comprehensively assess the relationship of MetS and OA.

RESULTS

We first detected an extensive genetic correlation between MetS and OA (rg = 0.393, P = 1.52 × 10-18), which was consistent in 4 MetS components, including waist circumference, triglycerides, hypertension, and high-density lipoprotein cholesterol and OA with rg ranging from -0.229 to 0.490. We then discovered 32 variants jointly associated with MetS and OA through Multi-Trait Analysis of GWAS (MTAG). Co-localization analysis found 12 genes shared between MetS and OA, with functional implications in several biological pathways. Finally, Mendelian randomization analysis suggested genetic liability to MetS significantly increased the risk of OA, but no reverse causality was found.

CONCLUSION

Our results illustrate a common genetic architecture, pleiotropic loci, as well as causality between MetS and OA, potentially enhancing our knowledge of high comorbidity and genetic processes that overlap between the 2 disorders.

Association between osteoarthritis and cognitive function: results from the NHANES 2011-2014 and Mendelian randomization study

Background

Previous meta-analyses have demonstrated osteoarthritis (OA) is associated with an increased risk of dementia, but these studies were prone to bias based on residual confounding factors and reverse causality.

Objectives

We aimed to investigate associations between OA and cognitive function using data from the National Health and Nutrition Examination Survey (NHANES) and to investigate the causality using Mendelian randomization (MR).

Design

This is a cross-sectional study and MR study.

Methods

Data from the NHANES 2011-2014 were used. Multiple linear, logistic regressions and stratified analyses were used to determine the association between OA status and cognitive function. Sample weights were used to ensure result generalizability. Two-sample MR analysis was conducted to examine the association between OA and dementia. Mediation analyses were performed to investigate the mediating effects of depression.

Results

We did not demonstrate a significant association between OA and cognitive performance after adjusting for relevant covariates (p > 0.05), and the population of individuals with both OA and depression was associated with higher odds of low total word recall cognitive performance (odds ratio (OR) = 4.74, 95% confidence interval (CI): 1.09-20.63; p = 0.04). Genetically predicted specific-site OA was not significantly associated with the risk of dementia (OR = 1.12; 95% CI: 0.96-1.32; p = 0.16), Alzheimer's disease (OR = 0.95, 95% CI: 0.68-1.31, p = 0.74), vascular dementia (OR = 1.32, 95% CI: 0.82-2.13, p = 0.25) with accepted heterogeneity and no evidence of directional pleiotropy. Furthermore, major depression was found to mediate the pathway between OA and vascular dementia (β = 0.044, 95% CI: -0.391 to 0.479, p < 0.05).

Conclusion

Our findings indicate that there is no significant association or causal relationship between OA and cognitive decline. However, depression may serve as an important factor influencing cognitive outcomes. Future research should further explore the bidirectional causal relationship and underlying mechanisms.

Genetic insights into the risk of hip osteoarthritis on stroke: A single-variable and multivariable Mendelian randomization

BACKGROUND

Hip osteoarthritis has been identified as a potential risk factor for stroke, with previous studies have demonstrated an association between hip osteoarthritis and stroke. This study aims to further elucidate the causal relationship between the two, employing Two-Sample and Multivariable Mendelian randomization methods.

METHODS

SNPs, derived from two extensive GWAS, served as instruments in exploring the association between genetically predicted hip osteoarthritis and stroke risk, utilizing two-sample Mendelian randomization. In Multivariable Mendelian randomization, factors such as cigarettes per day, alcoholic drinks per week, hypertension, body mass index, type 2 diabetes, C-reactive protein, rheumatoid arthritis were incorporated to further account for the independent causal effects of multiple correlated exposures.

RESULTS

Two-sample Mendelian randomization analysis revealed that hip osteoarthritis exerts a potential causal effect on any stroke, any ischemic stroke, and cardioembolic stroke, while it did not influence large artery stroke and small vessel stroke. Multivariable MR analysis indicated that the causal effect of hip osteoarthritis on any ischemic stroke and cardioembolic stroke was no longer evident after adjusting for C-reactive protein, and similarly, the effect on any ischemic stroke was not observed after adjusting for type 2 diabetes. However, the effects on any stroke, any ischemic stroke, and cardioembolic stroke remained significant after adjustments for hypertension, alcoholic drinks per week, cigarettes per day, body mass index, and rheumatoid arthritis.

CONCLUSION

The study demonstrated that elevated hip osteoarthritis, as predicted by genetic factors, was potential associated with an increased risk of any stroke, any ischemic stroke, and cardioembolic stroke, but showed no correlation with hypertension, alcoholic drinks per week, cigarettes per day, type 2 diabetes, C-reactive protein, body mass index levels, and rheumatoid arthritis.

Response eQTLs, chromatin accessibility, and 3D chromatin structure in chondrocytes provide mechanistic insight into osteoarthritis risk

Osteoarthritis (OA) poses a significant healthcare burden with limited treatment options. While genome-wide association studies (GWASs) have identified over 100 OA-associated loci, translating these findings into therapeutic targets remains challenging. To address this gap, we mapped gene expression, chromatin accessibility, and 3D chromatin structure in primary human articular chondrocytes in both resting and OA-mimicking conditions. We identified thousands of differentially expressed genes, including those associated with differences in sex and age. RNA sequencing in chondrocytes from 101 donors across two conditions uncovered 3,782 unique eGenes, including 420 that exhibited strong and significant condition-specific effects. Colocalization with OA GWAS signals revealed 13 putative OA risk genes, 6 of which have not been previously identified. Chromatin accessibility and 3D chromatin structure provided insights into the mechanisms and conditional specificity of these variants. Our findings shed light on OA pathogenesis and highlight potential targets for therapeutic development.

Genetic associations of plasma metabolites with immune cells in hyperthyroidism revealed by Mendelian randomization and GWAS-sc-eQTLs xQTLbiolinks analysis

Mendelian randomization (MR) was employed to investigate the causal relationships between immune cell phenotypes, hyperthyroidism (HD), and potential metabolic mediators. In this study, we acquired 731 immune cell phenotypes from genome-wide association studies (GWAS) (n = 18,622), HD data from the research by Handan Melike Dönertaş et al. (3,731 cases, 480,867 controls), and aggregated statistics of 1,400 blood metabolites from UK Biobank (n = 115,078). Bidirectional MR analysis was performed to explore the causal relationships between the immune cell phenotypes and HD, and two-sample and multi-variable MR were conducted to identify the potential plasma metabolites mediating in HD. In addition, sensitivity analyses were used to evaluate robustness, heterogeneity, and horizontal pleiotropy of results. Single-cell transcriptome-based exploration of potential key molecule and mechanism by which plasma metabolites regulated the immune cell differentiation in HD pathogenesis. Co-localization analysis was using single-cell eQTL (sc-eQTL) data with key molecule to probe genetically shared effects. Two-sample MRshowed that CD25 on naive-mature B cell, CD8 + NKT cell, and thymol sulfate level were found to have causal relationships with HD (P < 0.008). The causal relationship between thymol sulfate and HD were further validated in an independent cohort using the inverse-variance weighted (IVW). In addition, CD25 on naive-mature B cells and CD8 + NKT cells were both negatively correlated with thymol sulfate (P < 0.05). The results remained significant after MR-Egger and MR-PRESSO correction for horizontal pleiotropy and heterogeneity (P > 0.05). Multi-variable MR results showed that CD25 on naive-mature B cell and CD8 + NKT cell mediated 8.67% and 10.4% of the associations between thymol sulfate and HD, respectively. Moreover, thymol sulfate mediated the evolution of CD8 + NKT cells in the immune microenvironment, identifying PTPRC, PTK2B, KDM5A and TIGIT as the key participating molecules. Co-localization analysis showed that the key molecules had significant genetic sharing effects with CD8 + NKT cells (PPH4 > 0.75, R2 > 0.8, P < 0.05), with PTK2B having the broadest sharing interval. Current MR study provides evidence supporting causal relationships between several specific immune cell phenotypes and HD, as well as potential mediating metabolites. Thymol sulfate may increases the risk of HD pathogenesis by mediating the evolution of PTK2B genetic variants inducing CD8 + NKT cells in the progression of the immune microenvironment.

CAUSALdb2: an updated database for causal variants of complex traits

Unraveling the causal variants from genome wide association studies (GWASs) is pivotal for understanding genetic underpinnings of complex traits and diseases. Despite continuous efforts, tools to refine and prioritize GWAS signals need enhancement to address the direct causal implications of genetic variations. To overcome challenges related to statistical fine-mapping in identifying causal variants, CAUSALdb has been updated with novel features and comprehensive datasets, morphing into CAUSALdb2. This expanded repository integrates 15 057 updated GWAS summary statistics across 10 839 unique traits and implements both LD-based and LD-free fine-mapping approaches, including innovative applications of approximate Bayes Factor and SuSiE. Additionally, by incorporating larger LD reference panels such as TOPMED and UK Biobank, and integrating functional annotations via PolyFun, CAUSALdb2 enhances the accuracy and context of fine-mapping results. The database now supports interrogation of additional causal signals and offers sophisticated visualizations to aid researchers in deciphering complex genetic architectures. By facilitating a deeper and more precise characterisation of causal variants, CAUSALdb2 serves as a crucial tool for advancing the genetic analysis of complex diseases. Available freely, CAUSALdb2 continues to set benchmarks in the post-GWAS era, fostering the development of targeted diagnostics and therapeutics derived from responsible genetic research. Explore these advancements at http://mulinlab.org/causaldb.

The impact of different types of physical activity on the risk of knee osteoarthritis: A Mendelian randomization study

BACKGROUND

We aim to evaluate the causal relationship between different types of physical activity and the risk of knee osteoarthritis (KOA) through a two-sample Mendelian randomization study.

METHODS

We performed a two-sample Mendelian randomization analysis using publicly available Genome-wide association study associated with physical activity (460 376 individuals) and KOA (403 124 individuals). Two-sample Mendelian randomization analyses were performed to investigate the effects of exposure traits on KOA risk.

RESULTS

In this Mendelian randomization analysis, we investigated the impact of different types of physical activity on the risk of KOA. Light do-it-yourself and walking for pleasure demonstrated a protective effect on the risk of KOA (P = 8.19 × 10-4 and P = 4.24 × 10-6, respectively). No statistically significant differences were observed for heavy do-it-yourself, strenuous sports, other exercises or physical inactivity.

CONCLUSION

This study has revealed that engaging in light do-it-yourself activities and walking may serve as potential protective factors against KOA. These findings underscore the significance of introducing such activities into public health strategies designed for the prevention and management of KOA. Additional research is warranted to reveal the underlying mechanisms further.

Unraveling the relationship between obstructive sleep apnea and osteoarthritis: A multivariate mendelian randomization highlighting the role of BMI as a confounding factor

BACKGROUND

Osteoarthritis (OA) and obstructive sleep apnea (OSA) are prevalent chronic conditions with emerging evidence suggesting a potential link. However, the causality of this association remains unclear, possibly influenced by confounders like high body mass index (BMI). This study aimed to explore causal relationships between OA and OSA using Mendelian randomization (MR).

METHODS

MR analysis was performed to assess causality between OA and OSA. Inverse variance weighting (IVW) was the primary MR method, complemented by sensitivity analyses, including MR steiger, MR-Egger, MR-PRESSO, weighted median, heterogeneity tests, and leave-one-out approaches to evaluate pleiotropy and confirm the robustness of the causal estimates. To exclude confounding effects of BMI, we also used a multivariate MR (MVMR).

RESULTS

After adjusting for BMI through MVMR, no significant causal relationship was identified between genetically predicted OSA and OA phenotypes, including knee (KOA) and hip osteoarthritis (HOA), suggesting that obesity largely drives the observed relationship between these conditions. Similarly, MR steiger doesn't support a causal effect from OA on OSA. Sensitivity analyses confirmed the robustness of these results, with no significant evidence of horizontal pleiotropy or heterogeneity affecting outcomes. The findings indicate that BMI acts as a critical confounder in the relationship between OSA and OA, rather than OSA directly contributing to OA development.

CONCLUSIONS

Our findings indicate that there is no significant causal relationship between genetically predicted OSA and OA after adjusting for BMI. These findings underscore obesity as the primary shared risk factor, highlighting the importance of weight management as a key strategy for mitigating the risks of both conditions. Future research should aim to validate these findings in diverse populations and explore other metabolic pathways that may contribute to these complex associations.

Causal effects of circulating inflammatory proteins on knee and hip osteoarthritis: A two sample Mendelian randomization study

INTRODUCTION

Numerous circulating proteins are linked to the presence or severity of joint inflammation. However, traditional studies could not explain whether these protein biomarkers are proximate to disease progression.

METHOD

We conducted a study to explore the causal effects of 91 circulating inflammation-related proteins (CIPs) on knee osteoarthritis (KOA) and hip osteoarthritis (HOA), using two-sample Mendelian randomization (MR). The primary analysis utilized the inverse variance weighted (IVW) method, augmented by complementary approaches including weighted median, weighted mode, simple median, MR-Egger, and MR-PRESSO analysis. Sensitivity analysis validated the robustness of the results and ensured the absence of heterogeneity and horizontal pleiotropy.

RESULTS

We identified 2 CIPs with a causal effect on KOA, including CXCL9 (OR = 1.249, 95% CI = 1.046-1.492, P = 0.014) and TNF-β (OR = 1.105, 95% CI = 1.014-1.204, P = 0.023). Additionally, 3 CIPs were found to have a causal effect on HOA, including CXCL6 (OR = 1.058, 95% CI = 1.004-1.116, P = 0.035), RANKL (OR = 1.067, 95% CI = 1.002-1.137, P = 0.044), and VEGFA (OR = 1.072, 95% CI = 1.008-1.140, P = 0.027).

CONCLUSIONS

In the current study, our findings indicated that CXCL9 and TNF-β had the potential to influence the risk of KOA, while CXCL6, RANKL, and VEGFA could impact the risk of HOA. These discoveries underscored the significance of these proteins as potential targets for intervention in the prevention and treatment of KOA and HOA. Key Points • We presented genetic evidence supporting a causal link between circulating inflammatory proteins associated with joint inflammation using MR methods. • 5 CIPs have demonstrated promotive effects on the occurrence of KOA and HOA.

Investigating the Impact of Circulating MicroRNAs on Knee and Hip Osteoarthritis: Causal Links, Biological Mechanisms, and Drug Interactions

Osteoarthritis (OA), particularly in the knee and hip, poses a significant global health challenge due to limited therapeutic options. To elucidate the molecular mechanisms of OA and identify potential biomarkers and therapeutic targets, we utilized genome-wide association studies (GWAS) and cis-miRNA expression quantitative trait loci (cis-miR-eQTL) datasets to identify miRNAs associated with OA, revealing 16 that were linked to knee OA and 21 to hip OA. Among these, hsa-miR-1303 was significantly upregulated in both knee and hip OA (IVW: p = 6.8164×10-36 and 4.7919×10-2 respectively, OR > 1) and identified as a key factor in disease progression. Hsa-miR-1303 potentially regulates 30 genes involved in critical signaling pathways, such as the neurotrophin signaling pathway, and interacts with competing endogenous RNAs (ceRNAs) like circ_0041843 and LINC01338, thereby influencing key regulatory proteins such as SUMO2 and PARP1. Pharmacologically, hsa-miR-1303 targets nine druggable genes, including NRAS, H2AZ1, and RPS3, which have implications for drugs like cantharidin and diindolylmethane, potentially critical for developing novel OA treatments. Conversely, hsa-miR-125a-5p and hsa-miR-125b-5p, which are downregulated in both knee and hip OA, are associated with pathways such as HIF-1 and JAK-STAT, which modulate apoptotic signaling and transcriptional regulation. These miRNAs also interact with ceRNAs such as circ_0000254 and SPACA6P-AS, impacting proteins like STAT3, MCL1, and TRAF6. A drug interaction analysis identified 47 potential treatments, including Resveratrol and Acetaminophen, suggesting new therapeutic possibilities for OA management. This study not only highlights the role of miRNAs like hsa-miR-1303 and hsa-miR-125 in OA but also opens avenues for miRNA-based therapeutic development.

'QuickDASH' to find unique genes and biological processes associated with shoulder osteoarthritis: a prospective case-control study

OBJECTIVE

Osteoarthritis (OA) is a disease impacting the synovial joint complex, yet transcriptional changes specific to shoulder OA remain underexplored. This study aims to profile transcriptomic changes in periarticular tissues from patients undergoing shoulder replacement for OA. By correlating these profiles with QuickDASH scores-a validated measure of worsening shoulder function-this research seeks to understand the gene expression changes associated with clinical decline. Capsular tissue biopsies from shoulder OA patients were compared with those from a control group undergoing shoulder stabilization for recurrent instability. This investigation forms part of a larger transcriptomic analysis of painful shoulder conditions which will address the current gap in knowledge regarding the molecular and genetic underpinnings of shoulder OA, rotator cuff tears and cuff-tear arthropathy.

RESULTS

The analysis revealed that genes most strongly associated with increasing QuickDASH scores across tissues were linked to inflammation and stress response. Key pathways involved interleukins, chemokines, complement components, nuclear response factors, and immediate early response genes, reflecting a balance between pro- and anti-inflammatory signalling. Additionally, this study identified unique gene expression patterns in shoulder OA not previously observed in hip and knee OA, along with novel genes implicated in shoulder OA, highlighting areas for future targeted investigation. Trial registration This investigation has been registered with the Australian New Zealand Clinical Trials Registry (ANZCTR), registered on the 26th of March 2018, registration number: 12618000431224, accessible from: https://anzctr.org.au/Trial/Registration/TrialReview.aspx?id=374665&isReview=true.

The effect of cheese intake on osteoarthritis: a Mendelian randomization study

Introduction

Osteoarthritis (OA) is a debilitating chronic disease with a high prevalence, characterized by progressive degeneration of articular cartilage that leads to joint dysfunction, pain, and disability. Observational studies investigating the link between cheese intake and OA have yielded inconclusive results and may be susceptible to confounding.

Material and methods

We performed a two-sample Mendelian randomization (MR) investigation to evaluate the causal association between cheese intake and OA based on genome-wide association studies (GWAS). The primary analysis employed the inverse variance weighted (IVW) method, while complementary analyses were conducted using the weighted median, MR-Egger, and weighted mode methods. Moreover, we weighted each single nucleotide polymorphism's (SNP) effect on OA by its effect on cheese intake and subsequently meta-analyzed these estimates utilizing a fixed-effects model to provide a summary effect estimate. To assess the robustness of the outcomes, we performed a sensitivity analysis.

Results

Our two-sample MR analysis revealed an inverse causal relationship between cheese intake and several types of OA, including self-reported OA (odds ratio (OR) = 0.96, 95% confidence interval (CI) = 0.94-0.97, p = 6.70 × 10-7), OA of the hip or knee (OR = 0.59, 95% CI = 0.48-0.72, p = 1.38 × 10-7), knee OA (OR = 0.52, 95% CI = 0.42-0.66, p = 4.11 × 10-8), and hip OA (OR = 0.72, 95% CI = 0.53-0.96, p = 0.0268). Additionally, the fixed-effects model also demonstrated a causal inverse association between cheese intake and OA, with a pooled meta-analysis OR of 0.95 (95% CI = 0.94-0.97, p < 0.0001).

Conclusions

Our findings provided compelling genetic evidence of causal inverse associations between cheese intake and various types of OA, including self-reported OA, OA of the hip or knee, knee OA, and hip OA, which may enhance the efficacy of OA prevention by deepening our comprehension of the involved risk factors.

Causal associations between circulating immune cells and osteoarthritis: A bidirectional mendelian randomization study

PURPOSE

Osteoarthritis (OA) is a common degenerative joint disease, with its etiology remaining poorly understood. Our study aims to explore the causal associations between immune cells and OA, with the goal of generating a new perspective for targeted intervention strategies.

METHODS

A bidirectional two-sample Mendelian randomization (MR) analysis was performed to estimate the causality between multiple circulating immune cells and different sites of OA. The immune cell traits analyzed included the counts of circulating white blood cells (WBC), lymphocytes, monocytes, neutrophils, eosinophils, and basophils, as well as certain subsets of T and B lymphocytes. The OA types included were OA at any site, knee OA, hip OA, spine OA, thumb OA, and hand OA. Inverse-variance weighted (IVW), MR-Egger, weight median and weight mode were used to evaluate causal effects, with IVW being the main analysis method. Sensitivity analyses were conducted to assess heterogeneity and pleiotropy.

RESULTS

Our findings indicated that resting regulatory T cell (Treg) absolute counts (AC) were causally associated with an increased risk for spine OA [odds ratio (OR), 1.051; 95 % confidence interval (CI), 1.018-1.086; P=0.0005, PFDR=0.0350], and spine OA showed a positive causal relationship with the neutrophils count (OR, 1.104; 95 %CI, 1.032-1.181; P=0.0039, PFDR=0.0233). Besides, OA at any site was correlated with a rise in circulating eosinophils count (OR, 1.05; 95 %CI, 1.021-1.079; P=0.0007, PFDR=0.0041), while knee OA was associated with decreased total WBC (OR, 0.945; 95 %CI, 0.912-0.979; P=0.0016, PFDR=0.0048) and monocytes counts (OR, 0.958; 95 %CI, 0.934-0.982; P=0.0007, PFDR = 0.0041). No evidence of heterogeneity or horizontal pleiotropy was detected.

CONCLUSIONS

Our study has demonstrated the causal associations between multiple immune cells and diverse joint OA. These results highlight the intricate interplay between immune cells and OA, suggesting potential targets for therapeutic interventions to manage disease progression and alleviate symptoms.

The impact of coffee consumption on osteoarthritis: insights from NHANES and Mendelian randomization analysis

Background

Osteoarthritis (OA) is a prevalent degenerative joint condition, and emerging evidence suggests that dietary factors, such as coffee consumption, may influence its risk. However, the relationship between coffee consumption and the risk of developing OA remains ambiguous. This study aims to explore the association between coffee intake and OA complemented by Mendelian randomization (MR) to infer causality.

Materials and methods

We analyzed data from 32,439 participants across 10 NHANES cycles (1999-2018), including 3,676 individuals diagnosed with OA. Osteoarthritis was diagnosed through a structured questionnaire, while coffee consumption was assessed via 24-h dietary recalls. Participants were categorized based on reported coffee intake: 0 cups, <2 cups, 2-4 cups, and >4 cups per day. We employed weighted multivariable logistic regression to examine associations between coffee consumption and OA by using data from the NHANES 1999-2018, adjusting for various covariates. Subsequently, a MR analysis was conducted using genetic variants as instrumental variables to infer causal relationships, with multiple methods including inverse-variance weighted (IVW) analysis, MR-Egger regression, and weighted median techniques to assess the robustness, heterogeneity, and potential pleiotropy of our findings.

Results

Our regression models indicated an increased risk of OA with rising coffee consumption, with significant associations noted particularly for those consuming more than 4 cups daily (OR = 1.19, 95% CI: 1.00-1.41, p = 0.049). In MR analysis, coffee intake was causally linked to OA types, demonstrating increased risk for knee OA (KOA: OR = 1.60, 95% CI: 1.08-2.35, p = 0.018), hip OA (HOA: OR = 1.85, 95% CI: 1.06-3.25, p = 0.031), and combined KOA and HOA (KHOA: OR = 1.66, 95% CI: 1.18-2.33, p = 0.003). Sensitivity analyses confirmed the stability of results across multiple evaluation methods.

Conclusion

Our findings highlight a significant association between coffee consumption and an increased risk of OA, suggesting that higher intake levels may contribute to OA morbidity. These results warrant further exploration into the underlying biological mechanisms and implications for dietary guidelines in populations at risk for OA.

A scoping review of statistical methods to investigate colocalization between genetic associations and microRNA expression in osteoarthritis

Background

Genetic colocalization analysis is a statistical method that evaluates whether two traits (e.g., osteoarthritis [OA] risk and microRNA [miRNA] expression levels) share the same or distinct genetic association signals in a locus typically identified in genome-wide association studies (GWAS). This method is useful for providing insights into the biological relevance of genetic association signals, particularly in intergenic regions, which can help to elucidate disease mechanisms in OA and other complex traits.

Objectives

To review the existing literature on genetic colocalization methods, assess their suitability for studying OA, and investigate their capacity to integrate miRNA data, while bearing in view their statistical assumptions.

Design

We followed scoping review methodology and used Covidence software for data management. Search terms for colocalization, GWAS, and genetic or statistical models were used in the databases MEDLINE and EMBASE, searched till March 4, 2024.

Results

Our search returned 546 peer-reviewed papers, of which 96 were included following title/abstract and full-text screening. Based on both cumulative and annual publication counts, the most cited method for colocalization analysis was coloc. Four papers examined OA-related phenotypes, and none examined miRNA. An approach to colocalization analysis using miRNA was postulated based on further hand-searching.

Conclusions

Colocalization analysis is a largely unexplored method in OA. Many of the approaches to colocalization analysis identified in this review, including the integration of GWAS and miRNA data, may help to elucidate genetic and epigenetic factors implicated in OA and other complex traits.

Genetics of osteoarthritis

Osteoarthritis (OA) is the most common form of arthritis with well recognized multifactorial nature. While several environmental factors such as older age, obesity and previous joint injury are strongly associated with its development, a genetic influence on OA has been recognized for over 80 years. Identification of genes associated with OA has received considerable attention over the last two decades, aided by the rapidly evolving genotyping and sequencing technologies. More than 300 genomic loci have been identified to be associated with OA at different joints. These findings are likely to help our better understanding of the pathogenesis of OA and lead to important therapeutic and diagnostic advances in this most common disabling rheumatic disorder. This article will review the data that support the role of genetic factors in common idiopathic OA.

Nanomaterials: Recent Advances in Knee Osteoarthritis Treatment

Osteoarthritis (OA) of the knee is the most prevalent degenerative joint condition that places a substantial financial and medical burden on society. However, due to drawbacks such as inefficiency, adverse effects, and brief duration of action, the clinical efficacy of the current major therapies for knee OA is largely restricted. Therefore, novel medication development is highly required to address these issues. Numerous studies in recent years have established that nanomaterials can be a potential and highly effective way to overcome these challenges. In this review, the anatomical distinctions between healthy and OA knee joints, as well as novel advances in the field of nanomaterials for the treatment of knee OA are summarized. The limits of the present therapeutic strategies for treating knee OA are also highlighted, as well as the potential prospects of nanomaterials in the future.

Genetic proxies for therapy of insulin drug targets and risk of osteoarthritis: a drug-target Mendelian randomization analysis

BACKGROUND

The potential effects of insulin therapy on osteoarthritis (OA) risk are poorly understood. This study aimed to explore the causal relationship between insulin therapy and OA.

METHODS

Mendelian randomization (MR) analysis was performed to examine the association between genetically proxied inhibition of insulin targets and the risk of overall, hip (HOA) and knee OA (KOA). We then performed univariable MR using summary statistics regarding insulin target genes derived from the DrugBank database. Data related to blood glucose reduction levels were used as a proxy for insulin levels. Two phenotypes, type 2 diabetes, and glycosylated hemoglobin levels, were selected as positive controls to confirm the direction and validity of the proxies. The OA datasets were derived from the UK Biobank cohort. Multivariable MR was adjusted for body mass index, sedentary behavior, cigarette smoking, frequency of alcohol intake, age, and genetic sex.

RESULTS

Genetically proxied insulin therapy was associated with an increased risk of overall OA [odds ratio (OR):1.2595; 95% confidence interval (CI):1.0810-1.4675] and HOA (OR:1.4218; 95%CI:1.1240-1.7985), which remained consistent across multiple MR methods. After adjusting for confounders, we found evidence supporting a significant causal link with a higher risk of overall OA and HOA. A further two-step MR analysis revealed no significant mediation effects from the six mediators in the associations.

CONCLUSION

There was a causal association between genetically proxied insulin therapy and a higher risk of OA, especially HOA.

α-klotho reduces susceptibility to osteoarthritis: evidence from cross-sectional studies and Mendelian randomization

Background

Despite extensive research, the association between serum α-klotho levels and osteoarthritis (OA) remains unclear, predominantly relying on findings from OA mouse models. This study used data from the National Health and Nutrition Examination Survey (NHANES) to conduct a cross-sectional study examining the relationship between α-klotho and human OA. In addition, we used Mendelian randomization (MR) to genetically infer a causal relationship between serum α-klotho and the three OA subtypes.

Method

A cohort of 12,037 subjects from NHANES (2007-2016) was analyzed. Multivariate logistic regression was utilized to examine the association between α-klotho concentration and OA, alongside subgroup analysis and interaction tests. Additionally, a two-sample bi-directional MR analysis was conducted to evaluate the relationship between serum α-klotho and three OA subtypes, including all OA, hip OA, and knee OA, employing the inverse variance weighting (IVW) method as the primary approach.

Results

Following adjustment for covariates, a nonlinear negative correlation between serum α-klotho and OA was observed (OR=0.77; 95% CI, 0.68-0.88, p < 0.0001). The IVW method revealed that higher serum α-klotho levels were associated with decreased susceptibility to hip OA (OR = 0.92, 95% CI: 0.87-0.98, P = 9.64×10-3). However, MR analysis did not establish a causal relationship between serum α-klotho and OA or knee OA. Inverse MR also indicated that the three subtypes of OA do not causally affect serum α-klotho concentrations.

Conclusions

In cross-sectional studies, α-klotho showed a nonlinear negative correlation with OA. MR analysis of outcomes was not identical to cross-sectional studies.

Eosinophil-to-Lymphocyte Ratio and Eosinophil Count as New Predictive Markers for Osteoarthritis

Purpose

Despite the association between peripheral blood inflammatory biomarkers and a range of inflammatory diseases, the role of these biomarkers in osteoarthritis (OA) progression remains unclear. Additionally, whether alterations in these inflammatory markers impact the prognosis of OA patients remains an understudied area. The aim of our study was to investigate the specific associations between peripheral blood inflammatory markers and OA progression and OA-related mortality.

Methods

Data were obtained from the National Health and Nutrition Examination Survey (NHANES) database from 1999 through 2018. The primary outcomes were all-cause mortality, cardiac mortality, and renal disease mortality, with information on the corresponding mortality rates for each participant obtained through association with the National Death Index (NDI). Multivariate logistic regression models were used to examine the relationship between peripheral blood lymphocyte counts and OA, and restricted cubic spline (RCS) analysis was utilized to assess whether there was a nonlinear relationship with OA and mortality of OA patients. Interaction and stratified analyses were employed to explore the association between peripheral blood leukocyte counts and OA.

Results

This study included 1077 OA patients and 21,612 non-OA participants. In model 3 fully adjusted for covariates, eosinophil-to-lymphocyte ratio (ELR) and eosinophil (EOS) were positive risk factors promoting the development of OA (OR = 3.26, 95% CI: 1.49-7.14; OR = 1.79, 95% CI: 1.12-2.88). In stratified models for age, sex, BMI, smoking status, and alcohol consumption, the associations of ELR and EOS with OA were significantly different. RCS curves showed a J-shaped relationship between ELR and EOS and all-cause mortality in patients with OA. ELR was also found to significantly up-regulate cardiac mortality and renal mortality in patients with OA (OR = 3.92, 95% CI: 1.68-9.14; OR = 22.55, 95% CI: 6.55-77.70), while EOS was only significantly positively correlation (OR = 3.68, 95% CI: 1.94-7.01).

Conclusion

A significant relationship was found between ELR, EOS and OA. In addition, ELR and EOS were identified as potential predictors of mortality from different causes in patients with OA.

Is there a genetic relationship between blood glucose and osteoarthritis? A mendelian randomization study

OBJECTIVE

The relationship between blood glucose levels and osteoarthritis (OA) is unclear. This study aimed to investigate the genetic causal relationship between blood glucose-related traits and OA.

METHODS

We first performed univariate Mendelian randomization (UVMR) analyses using published genome-wide association study (GWAS) datasets with fasting glucose (FG), 2 h-glucose post-challenge glucose (2hGlu), and glycosylated hemoglobin (HbA1c) as exposures, and hip osteoarthritis (HOA) and knee osteoarthritis (KOA) as outcomes; then, we performed inverse analyses of them. We used Inverse-variance weighted (IVW) analysis as the primary analysis, and sensitivity analyses were performed. Moreover, we performed multivariate Mendelian randomization (MVMR) to estimate the independent effect of exposure on outcome after adjusting for body mass index (BMI). Summarized data for blood glucose-related traits were obtained from the MAGIC Consortium study of the glucose trait genome and for OA from the UK Biobank and arcOGEN. Summarized data for BMI were obtained from the GIANT Consortium meta-analysis of individuals of European ancestry. A two-sided p value < 0.05 in UVMR was considered suggestive of significance when p < 0.0167 (Bonferroni correction p = 0.05/3 exposures) was considered statistically significant.

RESULTS

We found significant negative genetic causality of FG for HOA and KOA, and these associations remained significant after we adjusted for the effect of BMI [odds ratios (ORs) of 0.829 (0.687-0.999, p = 0.049) and 0.741 (0.570-0.964, p = 0.025)]. HbA1c also had an independent negative genetic causal effect on HOA after adjustment for BMI [0.665 (0.463-0.954, p = 0.027)]. At the same time, there was no evidence of reverse genetic causality of OA on blood glucose-related traits.

CONCLUSION

We further elucidated the relationship between blood glucose-related traits and OA by adjusting for the effect of BMI from a genetic causal perspective. This study provides new insights to further clarify the relationship between blood glucose levels and OA, as well as the pathogenesis, etiology and genetics of OA.

Genetically predicted circulating linoleic acid levels and risk of osteoarthritis: a two-sample mendelian randomization study

OBJECTIVES

This study aimed to provide insight into the effect of genetically predicted linoleic acid (LA) levels on osteoarthritis (OA).

METHODS

The LA dataset was obtained from the UK Biobank (UKBB) consortium and contained 114,999 samples. The OA discovery dataset was derived from MRC-IEU consortium and included 38,472 cases and 424,461 controls. The OA validation set was derived from a summary-level genome-wide association study (GWAS) and included 39,427 cases and 378,169 controls. Genetic variants strongly associated with LA (p < 5 × 10- 8) were extracted as instrumental variables (IVs). The inverse variance weighted (IVW) approach was adopted as the primary analysis method in this study. In addition, multiple sensitivity analysis methods were used to assess the reliability of our results.

RESULTS

The IVW approach showed that circulating LA levels were negatively associated with OA risk in the discovery set (odds ratio (OR) = 0.993, 95% confidence interval (95% CI): 0.988-0.998, p = 0.011). A consistent result was obtained in the validation set (OR = 0.904, 95%CI: 0.845-0.967, p = 0.003). These results were validated by sensitivity analysis.

CONCLUSION

This study provides new evidence for the causal relationship between LA and OA, which provides new insights for the treatment of OA.

Investigating the causal impact of gut microbiota on arthritis via inflammatory proteins using mendelian randomization

Previous studies have suggested a potential association between the gut microbiota and arthritis. However, the causal links between the gut microbiota and various types of arthritis, as well as the potential mediating role of inflammatory proteins, remain unclear. Mendelian randomization was used to explore the causal relationships between gut microbiota, inflammatory proteins, and various forms of arthritis (osteoarthritis, rheumatoid and psoriatic arthritis, and ankylosing spondylitis [AS]). The inverse variance-weighted method was the primary analytical approach used. Furthermore, we examined the mediating role of inflammatory proteins in the pathway linking the gut microbiota to arthritis. Sensitivity analyses were performed to verify the robustness of the findings, and enrichment analyses were conducted to investigate the biological functions and pathways involved. We identified 11 positive and 14 negative causal effects linking the genetic liability of the gut microbiota to arthritis. Similarly, 9 positive and 8 negative causal effects between inflammatory proteins and arthritis were identified. Notably, an increased abundance of the order Bacillales (odds ratio [OR] = 1.199, 95% confidence interval [CI] = 1.030-1.394, P = 0.019) and higher interleukin-7 levels (OR = 1.322, 95% CI = 1.004-1.741, P = 0.046) significantly elevated the risk of AS. Furthermore, interleukin-7 mediated 13.8% of the effect caused by the order Bacillales, with a mediation effect size of β = 0.025 (95% CI = 0.001-0.064). Sensitivity and supplementary analyses revealed no significant evidence of horizontal pleiotropy or heterogeneity. Overall, our findings demonstrate causal links between the gut microbiota, inflammatory proteins, and four arthritis types, highlighting the gut microbiota as a potential therapeutic target. Crucially, interleukin-7 not only strongly correlated with AS but also partially mediated the effect exerted by the gut microbiota on AS, suggesting that managing the gut microbiota to modulate inflammatory proteins could serve as an effective therapeutic strategy for arthritis.

Identification of genetic association between mitochondrial dysfunction and knee osteoarthritis through integrating multi-omics: a summary data-based Mendelian randomization study

OBJECTIVE

Association between mitochondrial dysfunction and osteoarthritis (OA) has been consistently investigated, yet their genetic association remains obscure. In this study, mitochondrial-related genes were used as instrumental variables to proxy for mitochondrial dysfunction, and summary data of knee OA (KOA) were used as outcome to examine their genetic association.

METHODS

We obtained 1136 mitochondrial-related genes from the human MitoCarta3.0 database. Genetic proxy instruments for mitochondrial-related genes from studies of corresponding gene expression (n = 31,684) and protein (n = 35,559) quantitative trait locus (eQTLs and pQTLs), respectively. Aggregated data for KOA (62,497 KOA cases and 333,557 controls) were extracted from the largest OA genome-wide association study (GWAS). We integrated QTL data with KOA GWAS data to estimate their genetic association using summary data-based Mendelian randomization analysis (SMR). Additionally, we implemented Bayesian colocalization analysis to reveal whether suggestive mitochondrial-related genes and KOA were driven by a same genetic variant. Finally, to validate the primary findings, replication study (24,955 cases and 378,169 controls) and multi-SNP-based SMR (SMR-multi) test was performed.

RESULTS

Through SMR analysis, we found that the expression levels of 2 mitochondrial-related genes were associated with KOA risk. Specifically, elevated gene expression levels of the IMMP2L (odds ratio [OR] = 1.056; 95% confidence interval [CI] = 1.030-1.082; P-FDR = 0.004) increased the risk of KOA. Conversely, increased gene expression levels of AKAP10 decreased the risk of KOA (OR = 0.955; 95% CI, 0.934-0.977; P-FDR = 0.019). Colocalization analysis demonstrated that AKAP10 (PP.H4 = 0.84) and IMMP2L (PP.H4 = 0.91) shared the same genetic variant with KOA. In addition, consistent results were found in replication study and SMR-multi test, further demonstrating the reliability of our findings.

CONCLUSIONS

In summary, our analyses revealed the genetic association between mitochondrial dysfunction proxied by mitochondrial-related genes and KOA, providing new insight into potential pathogenesis of KOA. Furthermore, these identified candidate genes offer the possibility of clinical drug target development for KOA. Key points • This is the first SMR study to explore the genetic association between mitochondrial dysfunction proxied by mitochondrial-related genes and KOA. • Sufficient evidence to support genetic association between the expression levels of AKAP10 and IMMP2L, and KOA • Our MR analysis may provide novel new insight into potential pathogenesis of KOA. • These identified candidate genes offer the possibility of clinical drug target development for KOA.

The effect of coffee consumption on three main bone disorders: a Mendelian randomization trial

INTRODUCTION

Despite a large number of observational studies examining the effect of coffee consumption(CC) on bone disorders(BDs), particularly, osteoarthritis(OA), osteoportic fracture(OF), and rheumatoid arthritis(RA), the conclusions are highly controversial. Thus, it is essential to examine the causal association between CC and BDs.

MATERIALS AND METHODS

Mendelian randomization (MR) analysis was performed to assess the causal influence of CC on OF, RA, and OA. The main endpoint was the odds ratio (OR) of the inverse variance weighted (IVW) approach. In addition, the weighted median (WM), MR-Egger regressions, MR-pleiotropy residual sum and outlier (MR-PRESSO) and multivariable MR (MVMR) were included in sensitivity analyses. Furthermore, the function of causal SNPs was evaluated by gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and protein-protein interaction networks.

RESULTS

Primary MR analysis based on the IVW method suggested that changes in CC alter risk of OF (OR = 1.383, 95%CI 1.079-1.853, P = 0.039), RA(OR: 1.623, 95%CI 1.042-2.527, P = 0.032) and HOA (hip osteoarthritis, OR = 1.536, 95% CI 1.044-2.259, P = 0.021). However, these causal relationships were not robust in sensitivity analyses. In contrast, there is a positive causal relationship between increased CC and the risk of KOA (knee osteoarthritis, OR: 2.094, 95%CI: 1.592-2.754, P = 1.41 × 10-7), as evidenced by the IVW using random effect. A similar effect size was observed across all MR sensitivity analyses, with no evidence of horizontal pleiotropy.

CONCLUSION

Based on our MR analysis, increased CC was causally linked to an increase in the risk of KOA. Genetic predictions suggested that CC reduction may have benefits for bone health.

Evaluation of circulating microRNA signature in patients with erosive hand osteoarthritis: The HOAmiR study

OBJECTIVES

To identify circulating micro-RNAs differentially expressed in patients with erosive hand osteoarthritis (HOA) compared to patients with non-erosive HOA and patients without HOA.

METHODS

In the screening phase, 768 well-characterized micro-RNAs using Taqman low-density array cards were measured in 30 sera from 10 patients with erosive HOA, 10 patients with non-erosive HOA, and 10 controls without HOA, matched for age and body mass index (BMI). In a second step, we validated the micro-RNAs identified at the screening phase (adjusted p value < 0.05 after false discovery rate correction using Benjamini-Hochberg method and literature review) in larger samples (60 patients with erosive HOA and 60 patients without HOA matched for age and BMI).

RESULTS

In the screening phase, we identified 21 down-regulated and 4 up-regulated micro-RNAs of interest between erosive HOA and control groups. Among these, 9 micro-RNAs (miR-373-3p, miR-558, miR-607, miR-653-5p, miR-137 and miR448 were down-regulated, and miR-142-3p, miR-144-3p and miR-34a-5p were up-regulated) were previously described in chondrocytes homeostasis or OA. We found only one significantly down-regulated micro-RNA between erosive and non-erosive HOA. In the validation phase, we showed replication of a single micro-RNA the significant downregulation of miR-196-5p, that had been previously identified in the screening phase among patients with erosive HOA compared to those without HOA. After reviewing the literature and the miRNA-gene interaction prediction model, we found that this microRNA could interact with bone homeostasis and HOXC8, which could explain its role in osteoarthritis.

CONCLUSIONS

We found that miR-196-5p was down-regulated in patients with erosive HOA and some of its targets could explain a role in OA.

Response eQTLs, chromatin accessibility, and 3D chromatin structure in chondrocytes provide mechanistic insight into osteoarthritis risk

Osteoarthritis (OA) poses a significant healthcare burden with limited treatment options. While genome-wide association studies (GWAS) have identified over 100 OA-associated loci, translating these findings into therapeutic targets remains challenging. Integrating expression quantitative trait loci (eQTL), 3D chromatin structure, and other genomic approaches with OA GWAS data offers a promising approach to elucidate disease mechanisms; however, comprehensive eQTL maps in OA-relevant tissues and conditions remain scarce. We mapped gene expression, chromatin accessibility, and 3D chromatin structure in primary human articular chondrocytes in both resting and OA-mimicking conditions. We identified thousands of differentially expressed genes, including those associated with differences in sex and age. RNA-seq in chondrocytes from 101 donors across two conditions uncovered 3782 unique eGenes, including 420 that exhibited strong and significant condition-specific effects. Colocalization with OA GWAS signals revealed 13 putative OA risk genes, 10 of which have not been previously identified. Chromatin accessibility and 3D chromatin structure provided insights into the mechanisms and conditional specificity of these variants. Our findings shed light on OA pathogenesis and highlight potential targets for therapeutic development.

Gut microbiota metabolic pathways: Key players in knee osteoarthritis development

OBJECTIVE

To confirm the causality of gut microbiota pathway abundance and knee osteoarthritis (KOA).

METHODS

Microbial metabolic pathways were taken as exposures, with data from the Dutch Microbiome Project (DMP). Data on KOA from the UK Biobank were utilized as endpoints. In addition, we extracted significant and independent single nucleotide polymorphisms as instrumental variables. Two-sample Mendelian randomization (MR) analysis was applied to explore the causal relationship between gut microbiota pathway abundance and KOA, and MR-Egger and weighted median were used as additional validation of the MR results. Meanwhile, Cochran Q, MR-Egger intercept, MR-PRESSO, and leave-one-out were used to perform sensitivity analyses on the MR results.

RESULTS

MR results showed that enterobactin biosynthesis, diacylglycerol biosynthesis I, Clostridium acetobutylicum acidogenic fermentation, glyoxylate bypass and tricarboxylic acid cycle were the risk factors for KOA. (OR = 1.13,95%CI = 1.04-1.23;OR = 1.12,95%CI = 1.04-1.20;OR = 1.14,95%CI = 1.04-1.26; OR = 1.06,95%CI = 1.00-1.12) However, adenosylcobalamin salvage from cobinamide I, hexitol fermentation to lactate formate ethanol and acetate, purine nucleotides degradation II aerobic, L tryptophan biosynthesis and inosine 5 phosphate biosynthesis III pathway showed significant protection against KOA. (OR = 0.93,95%CI = 0.86-1.00;OR = 0.94,95%CI = 0.88-1.00;OR = 0.91,95%CI = 0.86-0.97;OR = 0.95,95%CI = 0.92-0.99; OR = 0.91, 95%CI = 0.85-0.98) Further multiplicity and sensitivity analyses demonstrated the robustness of the results.

CONCLUSION

Our study identified specific metabolic pathways in gut microbiota that promote or inhibit KOA, which provides the most substantial evidence-based medical evidence for the pathogenesis and prevention of KOA.

Genetic predisposition to thyrotoxicosis and onset of knee osteoarthritis

Objective

Thyroid hormones have actions on cartilage, whereas the association between thyroid hormone related diseases and osteoarthritis (OA) are unclear. This study aims to investigate the association between thyrotoxicosis and OA.

Methods

Summary-level genetic data of thyrotoxicosis were obtained from FinnGen cohorts (nCase = 10,569, nControl = 762,037). Summary-level data of OA were obtained from a large-scale genome-wide association study of UK Biobank (nCase = 40,659, nControl = 756,338). Single nucleotide polymorphisms (SNPs) robustly associated with thyrotoxicosis or OA were used as genetic instruments. A two-sample bidirectional Mendelian randomization (MR) analysis was designed to assess the effect of genetic predisposition of thyrotoxicosis on OA risk, as well as the reverse their relationship. The causal effect was estimated by Inverse-variance weighted method, with weighted median and MR-Egger as supplementary methods.

Results

Genetic predisposition of thyrotoxicosis was associated with the onset of knee OA (autoimmune hyperthyroidism: odds ratio [OR]: 1.05, 95% confidence interval [CI]: 1.03-1.07, FDR < 0.001; thyrotoxicosis: OR: 1.05, 95% CI: 1.02-1.08, FDR = 0.016; thyrotoxicosis with diffuse goitre: OR: 1.04, 95% CI: 1.02-1.07, FDR = 0.003; other and/or unspecified thyrotoxicosis: OR: 1.05, 95% CI: 1.02-1.09, FDR = 0.003), whereas thyrotoxicosis was not associated with hip OA. In reverse MR analysis, genetic predisposition to OA was not associated with thyrotoxicosis. No pleiotropy was identified in the MR analyses. Sensitivity analyses indicated the robustness of the MR estimates.

Conclusion

This study provides MR evidence supporting causal association of thyrotoxicosis with knee OA in European population, whereas OA may have no causal effects on thyrotoxicosis.

Genetics of hip dysplasia - a systematic literature review

BACKGROUND

Developmental dysplasia of the hip (DDH) is a congenital condition affecting 2-3% of all newborns. DDH increases the risk of osteoarthritis and is the cause of 30% of all total hip arthroplasties in adults < 40 years of age. We aim to explore the genetic background of DDH in order to improve diagnosis and personalize treatment.

METHODS

We conducted a structured literature review using PRISMA guidelines searching the Medline, Embase and Cochrane databases. We included 31 case control studies examining single nucleotide polymorphisms (SNPs) in non-syndromic DDH.

RESULTS

A total of 73 papers were included for full text review, of which 31 were single nucleotide polymorphism (SNP) case/control association studies. The literature review revealed that the majority of published papers on the genetics of DDH were mostly underpowered for detection of any significant association. One large genome wide association study has been published (N = 9,915), establishing GDF5 as a plausible risk factor.

CONCLUSIONS

DDH is known to be congenital and heritable, with family occurrence of DDH already included as a risk factor in most screening programs. Despite this, high quality genetic research is scarce and no genetic risk factors have been soundly established, prompting the need for more research.

Basal metabolic rate mediates the causal relationship between gut microbiota and osteoarthritis: a two-step bidirectional Mendelian randomization study

Background

The relationship between gut microbiota and osteoarthritis (OA) occurrence remains unclear. Existing research needs to clearly understand how basal metabolic rate (BMR) regulates this relationship. Therefore, using a two-step bidirectional Mendelian Randomization approach, our study aims to investigate whether BMR levels mediate the causal relationship between gut microbiota and OA.

Methods

In this study, we examined publicly available summary statistics from Genome-Wide Association Studies (GWAS) to determine the correlation between gut microbiota and OA. The analysis included one primary dataset and two secondary datasets. Initially, a two-step, two-sample, and reverse MR analysis was performed to identify the causal relationship between gut microbiota and OA. Subsequently, a two-step MR analysis revealed that the relationship between microbiota and OA is mediated by BMR. Sensitivity analyses confirmed the robustness of the study results.

Results

In our analysis of the primary dataset, we discovered a positive correlation between three taxa and the outcome of OA, and eight taxa exhibited a negative correlation with the OA outcome. Through comparisons with the secondary dataset and multiple testing corrections, we found a negative association between the class Actinobacteria (OR=0.992886277, p-value = 0.003) and the likelihood of OA occurrence. Notably, knee osteoarthritis (KOA) and hip osteoarthritis (HOA) had a strong negative correlation (OR = 0.927237553/0.892581219). Our analysis suggests that BMR significantly mediates the causal pathway from Actinobacteria to OA, with a mediated effect of 2.59%. Additionally, BMR mediates 3.98% of the impact in the path from the order Bifidobacteriales and the family Bifidobacteriaceae to OA. Besides these findings, our reverse analysis did not indicate any significant effect of OA on gut microbiota or BMR.

Conclusion

Our research results indicate that an increase in the abundance of specific gut microbial taxa is associated with a reduced incidence of OA, and BMR levels mediate this causal relationship. Further large-scale randomized controlled trials are necessary to validate the causal impact of gut microbiota on the risk of OA. This study provides new insights into the potential prevention of OA by modulating the gut microbiota.

Causal Relationships between Circulating Immune Cell Traits and the Risk of Rheumatoid Arthritis and Osteoarthritis: A Bidirectional Two-Sample Mendelian Randomization Study

Background

Rheumatoid arthritis (RA) and osteoarthritis (OA) are prevalent chronic joint disorders with immunological pathogenesis. However, the causal relationships between circulating immune cells and them remain largely unknown. Therefore, we conducted a bidirectional two-sample Mendelian randomization (MR) study to determine their causal relationship.

Methods

Genome-wide association study summary statistics were extracted from publicly available databases regarding immune cell phenotypes, RA, and OA. MR analysis was conducted using five MR methods, with inverse-variance-weighted (IVW) as the primary analysis method. False discovery rate correction (FDR) was used to reduce the likelihood of type 1 errors. We also conducted MR-Egger intercept tests to evaluate horizontal pleiotropy.

Results

After FDR adjustment of the P values for the IVW method, the CD27 expression on memory B cells was negatively related to the risk of RA (P < 0.001), and the human leukocyte antigen (HLA)--DR expression on CD14+ monocytes was negatively related to the risk of OA (P < 0.001). We also found that RA was negatively associated with the expression of HLA-DR on myeloid dendritic cells (P < 0.001), but significant horizontal pleiotropy was observed.

Conclusion

Our study demonstrates a causal relationship between specific immune cell traits and RA as well as OA, providing further insight into the role of immune cells in the pathogenesis of these disorders.

Causal impact of statins on susceptibility to osteoarthritis: insights from a two-sample Mendelian randomization analysis

BACKGROUND

Osteoarthritis is a widely prevalent cause of pain and disability among older adults. It is an incurable condition, and most treatments are aimed at alleviating symptoms.

AIM

This study aimed to investigate the impact of statins on osteoarthritis by using a two-sample Mendelian randomization approach, using genetic variants associated with statin use as instrumental variables.

METHOD

Information on single nucleotide polymorphisms associated with statin medication was obtained from the FinnGen study, and data on osteoarthritis were sourced from the UK Biobank. The inverse variance weighted method was used as the primary analytical approach for the Mendelian randomization analysis. Sensitivity analyses were conducted to evaluate horizontal pleiotropy and heterogeneity. To examine the genetic relationship between statins and osteoarthritis, linkage disequilibrium score regression-based estimates were used.

RESULTS

Mendelian randomization analysis indicated a positive effect of statin use on the treatment of osteoarthritis (odds ratio 0.951, 95% confidence interval 0.914-0.99, p < 0.05). This conclusion was supported by various Mendelian randomization methods. Sensitivity analyses revealed no significant directional pleiotropy or influential single nucleotide polymorphisms that could compromise the overall causal inference. Linkage disequilibrium score regression-based estimates suggested a modest genetic correlation between statin use and osteoarthritis (Rg = 0.098, Se = 0.034, p < 0.05), thus reinforcing the robustness of the Mendelian randomization analysis.

CONCLUSION

Statins reduce the risk of osteoarthritis, aligning with the results of observational studies. Further research is essential to validate these results and explore the underlying mechanisms in detail.

Unraveling the genetic association between knee osteoarthritis and hallux deformities

OBJECTIVE

Knee osteoarthritis (KOA), hallux valgus (HV) and hallux rigidus (HR) are common musculoskeletal problems of the lower extremities. However, their underlying causal relationships are unclear. This study attempts to clarify the cause-and-effect relationship between KOA and the two common hallux deformities (HV and HR).

DESIGN

The summary-level statistics for KOA, HV, and HR were collected from genome-wide association studies (GWAS). The causal analysis of KOA on HV or HR was carried out using two-sample Mendelian randomization (MR). In order to assess the robustness of the MR results, sensitivity analyses were performed. In addition, multivariable MR (MVMR) was implemented to assess the influence of KOA in causation as well as calibrate the effect of anthropometric characteristics. Supplementary backward MR analysis was conducted to determine the causal effect of hallux diseases on KOA.

RESULTS

The univariable analysis indicated that KOA has a causative influence on HR (odds ratio [OR] = 1.29, 95% confidence interval [CI] = 1.18-1.41, P = 2.25E-8) and HV (OR = 1.43, 95% CI = 1.21-1.68, P = 2.76E-5). In the backward MR analyses, hallux deformities did not appear to be the cause of KOA. In the MVMR analysis, after jointly adjusting for the effects of waist-to-hip ratio (WHR), waist circumference (WC), hip circumference (HC) and BMI, the causal impact of KOA on HV and HR remained robust.

CONCLUSION

In this study, the genetic causality between KOA and increased risk of hallux deformities (HV and HR) is established, which can provide evidence-based recommendations for reducing the incidence of hallux deformities in KOA patients. Further high-level studies are warranted to validate the associations and explore its broader implications.